Note: Descriptions are shown in the official language in which they were submitted.
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POSITIVE DISPLACEMENT VARIABLE SPEED TRANSMISSION WITH DUAL
MOTION DRIVE GEARS
Field of the Invention
The present invention relates to a transmission that is capable of defining,
and
operating over, a large range of gear ratios.
Background to the Invention
From nearly the beginning of mechanical engines, the purpose and design of an
engine has been focused, to at least some degree, on allowing a small engine
to
io move a large load. As engines evolved and technology became more
sophisticated, engines were developed having transmissions with multiple
ratios to
allow the engine to start moving the load with a low ratio and to
incrementally step
up to higher ratios as the load began moving. In this manner, a transmission
can
make more effective use of the engine's torque and keep the engine operating
near
an appropriate speed. Moreover, an engine can operate within a narrow range of
speeds while providing a wider range of output speeds.
To effect an incremental change in gear ratio, a manual transmission uses
various
separate driven gears of different sizes in connection with one or more drive
gears.
As a gear ratio change is made, a drive gear disengages from the driven gear
and
re-engages with a different gear. For example, a clutch may disengage a drive
gear from a driven gear and then re-engage the same or a different drive gear
with
a second driven gear having a different radius. As the newly engaged gears
have
different radii-or levers-the gear ratio is changed. To effect this gear ratio
change, however, the drive gear must be temporarily disconnected from all
driven
gears, such that the power source is also temporarily disconnected from the
load
while the gear ratio change is made. While temporary, the disengagement
between the drive and driven gears lasts long enough to be perceived by an
operator of machinery utilizing the transmission, and long enough that when
the
drive and driven gears are reengaged with each other, a potentially damaging
torque spike may occur.
Automatic transmissions also make incremental changes in gear ratio by
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disconnecting the engine from the load. To do so, automatic transmissions
typically use one or more planetary gear sets which are used in connection
with a
series of clutches and bands that are controlled by a hydraulic system. To
change
between gear ratios, valves within the hydraulic system are used to control
hydraulic pressure which activates various clutches and bands so as to connect
and disconnect the carriers and various gears of the automatic transmission
from
the engine. Based on the specific clutches and bands that engage and
disengage,
the transmission achieves a predetermined gear ratio change.
When the power source is disconnected or disengaged from the load, the load
io must coast until the power source is reconnected. For anything more than
disconnection over a negligible amount of time, the load then coasts and
significant
momentum can be lost. For instance, a semi-tractor trailer or other moving
vehicle
may be moving uphill when a gear change is required. By pushing in the clutch
or
otherwise disconnecting the power source of the semi-tractor trailer, the
engine
RPMs are decreased, turbos may be dumped, and torque can no longer be applied
in the movement of the load. As a result, the driver often must shift two or
three
gears down because re-engaging the power source will not occur fast enough to
maintain the engine RPMs at a drop of only one or two gears down. This results
in
an inefficient use of the engine horsepower and fuel.
Similarly, where a tractor is pulling a load such as a plow, temporarily
disconnecting the engine from the load so as to change gear ratio reduces the
momentum of the tractor and the plow. While the tractor may be able to coast,
the
plow is less likely to coast. For example, when the plow loses enough momentum
it may catch on the ground being plowed and thereby drag against and stop the
tractor from coasting. The plow may catch and stop with a sudden movement that
can damage the tractor and potentially injure the operator. Therefore, to
avoid
damage and injury, the tractor operator may drive the tractor and plow in a
low gear
to avoid the need to shift gears although a higher gear would allow the
tractor to
more quickly plow the field, consume fuel more efficiently, and make use of
the
momentum to obtain a draft of the plow.
In addition, many other applications have previously been unable to take
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advantage of the benefits of a variable speed transmission because
disconnection
of the power source from the load makes the application unsafe or impractical.
For
example, an elevator could benefit from gear ratio changes to change the speed
of
its ascent or descent. However, disconnecting the power source during ascent
or
descent would cause the elevator carriage to coast, or free-fall, and could
make the
variable speed transmission unsafe for the elevator passengers.
A conveyor system such as those used in manufacturing or mining operations
could also benefit from variable speeds. For example, as the system starts up
the
conveyor belt could be started at a slow speed and the speed then increased
for
1o full operation. Many conveyor belts are, however, loaded with material
and/or are
miles long, thereby creating a large load that must be moved. If a gear ratio
change were to be made by even temporarily disconnecting the power source, the
material and conveyor belt would lose momentum and prevent an effective gear
ratio change. Consequently, materials often have to be removed from the belt
just
to get the conveyor moving, and/or the conveyor system must be operated at a
constant speed.
While variable speed transmissions provide many benefits, the significant
disconnection of the power source from the load in these traditional
transmissions
has caused engine and transmission designers to search for methods and systems
that minimize the time the power source is disconnected and a drive gear is
disengaged. To at least some degree, automatic engines have reduced this time
by automating the shifting between gears and changing gear ratios, thereby
also
reducing the time between disconnection and reconnection of the power supply
to
the load. However, even automatic engines disconnect the engine from the drive
gears for a time long enough to cause a potentially significant loss in
torque,
thereby failing to make an efficient use of the available horsepower.
Moreover, by
operating with only a very limited number of discrete gear ratios, that may be
relatively widely spaced, the engine operates mostly in an inefficient range.
Consequently, the engine must be capable of providing more horsepower, and
must thus be larger, than would otherwise be required if an engine was more
frequently running at an efficient speed. The inefficient use of 'these
engines, in
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turn, burns more fuel than would an engine run at more efficient speeds.
While decreasing the time needed to change between gear ratios also decreases
the time during which the load and the power source are disconnected, it can
also
create greater torque spikes which may damage the drive train. In particular,
as a
gear ratio change is made from one discrete gear ratio to another discrete
gear
ratio, engagement of the drive and driven gear may produce a torque spike such
that as the drive and driven gears engage, the torque produced momentarily
spikes. The torque spike can be reduced by feathering the clutch so as to
cause
the drive and driven gears to gradually re-engage. If, however, the shift is
made
io too quickly, the torque spike can produce an output torque large enough to
damage
a drive shaft, chassis, or an axel.
Accordingly, some efforts have been made to reduce a torque spike so as to
reduce the likelihood that the torque spike will cause damage. For example, a
torque spike anticipator may be used to artificially lower the torque as a
gear ratio
change is made. In particular, as a gear ratio change is made, the torque
spike
anticipator may lower the engine RPMs during the gear ratio change, such that
as
the gears re-engage to produce the new gear ratio, less torque is produced
during
the torque spike. Such a system adds, however, additional complexities to a
transmission and prevents operation at a constant velocity so as to make an
efficient use of the available power.
In low torque applications, the problems associated with disconnecting the
power
source from the load have been reduced, to some extent, by continuously
variable
transmissions (CVT) and infinitely variable transmissions (IVT). A CVT
typically
uses two pulleys which are connected by a belt. The pulleys can include two
cones
that face each other and which can be pulled together or pushed further apart
by
hydraulic pressure, centrifugal force or spring tension. As one pulley
increases its
radius, the other decreases its radius to keep the belt tight. As the two
pulleys
change their radii relative to one another, they create various gear ratios. A
similar
concept is embodied in an infinitely variable transmission (IVT) which also
makes
use of similar, complementary pulleys and cones. Instead of a belt, however,
the
IVT uses a rolling member that is sandwiched between the cones.
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Regardless of whether a CVT (wrapping member) or IVT (rolling member) is used,
however, the system relies on friction to adjust gear ratios and provide power
output. Friction introduces heat into the system, however, and, as a result,
the
wrapping member and rolling members heat up and are susceptible to wear
damage, thereby requiring that the user repair or replace the parts. To reduce
the
frequency of repair, the frictional wrapping or rolling members can be
toughened,
such as through the use of a thicker belt or impregnation of the belt with
metals or
other tougher materials. However, as the belt strength is increased, the part
costs
increase. Moreover, sufficiently tough materials can cause the cones within
the
i o transmission to wear and fail.
Moreover, because these systems are friction-based, they are typically only
suitable for low torque applications, as high torque applications could cause
excessive heating within the transmission, thereby causing even greater wear
and
failure of the transmission components. As a result, CVT and IVT transmissions
are not scalable for a wide variety of low and high torque applications. In
fact, the
application of torque to a CVT or IVT in a high torque or high horsepower
system
may cause near immediate failure as the rolling member or wrapping member can
melt or otherwise deteriorate due to the friction-induced heat.
Because the CVT and IVT have been seen as unacceptable alternatives in high-
torque applications, additional efforts have been made within high-torque
applications so as to provide little to no time gap between disconnection and
reconnection of the power source and load. For example, John Deere produces
tractors with a PowerShift transmission that uses a complex design which is
purported to automatically do the clutching and disconnect a load and
reconnect
the load at about the same time such that there is no real time gap and little
to no
torque loss. The transmission is, however, much larger than a standard
transmission, and can house a large number of hydraulic lines inside the
transmission. As a result, maintenance of the lines may be difficult, and the
size of
the engine further increases the size of the equipment and the weight or load
that
must be carried. Moreover, because of the complexity and size of the
transmission, it can be cost prohibitive for certain applications, and it is
not scalable
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for low torque or smaller applications.
Accordingly, a need exists for an improved transmission which is scalable and
which can switch between any of various gear ratios without requiring
disconnection of the power source from the load.
Summary of the Invention
According to one aspect of the present invention, a transmission comprises:
a transmission input interface comprising a rotatable input shaft;
one or more drive gears coupled at least indirectly to said transmission input
interface, each of said one or more drive gears being configured for
rotational
1o motion about a respective internal axis of the drive gear and -for orbital
motion
about a common external axis, wherein said rotational motion and said orbital
motion correspond to rotation of said rotatable input shaft;
one or more driven gears configured to engage said one or more drive
gears, such that said one or more drive gears are adapted to cause rotation of
said
one or more driven gears; and
a transmission output interface coupled at least indirectly to said one or
more driven gears.
This, and at least some other, transmissions of the present invention may
maintain
substantially constant engagement between at least one drive gear and at least
one driven gear at various gear ratios, and can also maintain such engagement
even while the transmission is in a neutral output state. By maintaining a
substantially constant engagement between at least one drive gear and at least
one driven gear, the transmission is able, when a load is being driven, to
implement
changes to an associated gear ratio while maintaining the connection of the
power
to the load.
According to another aspect of the invention, a transmission comprises:
a first transmission interface;
a first set of one or more power transmission members coupled at least
indirectly to said first transmission interface, each of said one or more
first power
transmission members being configured to travel along a respective orbital
path, a
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length of each orbital path of said first set of one or more power
transmission
members being selectively variable such that a unique gear ratio is defined
for
each orbital path length;
a second set of one or more power transmission members configured to
engage said first set of one or more power transmission members; and
a second transmission interface coupled to said second set of one or more
power transmission members.
Such a transmission may employ multiple gear ratios which are changeable in
small increments over a range of gear ratios. Preferably, the transmission
includes
1o a transmission input interface and at least one drive gear coupled to the
power
input and configured to orbit such that the orbital path enables power
transmission
through various gear ratios. One or more driven gears engage the drive gears
and
receive a torque input from one or more of the drive gears. Preferably, the
power
output interface is also coupled to the one or more driven gears and can
provide a
power output to a power sink or to one or more loads. Preferably, the orbital
path
of the drive gears is changeable such that the length of the orbital path can
be
increased or decreased so that by increasing or decreasing the length of the
orbital
path, the drive gears implement various gear ratios. The changing of the
length of
the orbital path allows the gear ratio associated with the transmission to be
changed between a plurality of discrete gear ratios, in very small increments.
According to another aspect of the present invention, a power transform system
comprises:
a first set of one or more power transmission members, each of which is
configured to accept a torque and, in response, rotate about its central axis
and
travel along a selectively changeable orbital path about an external axis; and
a second set of one or more power transmission members configured to
engage said first set of one or more power transmission members, so as to
enable
torque to be transferred therebetween, wherein said one or more first power
transmission members and said one or more second power transmission members
are adapted to collectively define a plurality of different gear ratios
responsive to
one or more changes to said orbital path of said first set of one or more
power
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transmission members.
In such a power transform system, first and second power transmission members
can receive a power input to either set of power transmission members such
that
torque can be transmitted through the transmission in either of two different
directions. That is, the set of first power transmission members can act as
either
drive or driven members, and the set of second power transmission members can
similarly act as driven or drive members, respectively.
1o According to a further aspect of the invention, another power transform
system
comprises:
a first set of one or more power transmission members, each of said first set
of one or more power transmission members being configured to travel along a
respective orbital path, a length of each orbital path of said first set of
one or more
power transmission members being selectively variable such that a different
gear
ratio is defined for each different length of said orbital path; and
a second set of one or more power transmission members in engagement
with said first set of one or more power transmission members, said second set
of
one or more power transmission members being configured to substantially
maintain engagement with said first set of one or more power transmission
members at each of said plurality of gear ratios.
According to another aspect of the invention, a transmission comprises:
a transmission input interface configured to receive a rotational power input;
one or more driving members coupled to said transmission input interface,
said one or more driving members being configured to selectively translate
radially
to any of a plurality of radial positions;
one or more driven members configured to engage said one or more driving
members, said one or more driven members being configured to receive said
power input from said driving members, and said one or more driven members
being configured to maintain substantially constant engagement with said one
or
more driving members at each of said plurality of radial locations of said one
or
more driving members; and
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a transmission output interface coupled to said one or more driven
members, said transmission output interface being configured to transmit a
torque
output corresponding to said torque input.
In such a transmission, a transmission input interface is included for
receiving a
rotational power output of another device. This example of the transmission
may
also include one or more radially movable input, or driving, members coupled
to the
transmission input interface such that the movable input members receive the
torque output by the other device. The input members engage with output, or
1o driven, members to which the torque is transmitted from the input members.
The
output members maintain engagement with the input members at various discrete
locations as the input members move also radially. A transmission output
interface
is also coupled to the output members to transmit a torque output to another
device
or devices.
According to another aspect of the invention, a transmission comprises:
a transmission input interface configured to receive a torque input;
a plurality of drive members coupled to said transmission interface, said
plurality of drive members being configured to collectively define a plurality
of gear
ratios;
a plurality of driven members configured to engage said plurality of drive
members, each of said plurality of driven members being configured to
translate
radially with respect to a central axis about which said plurality of drive
members
are arranged, each of said plurality of driven members being arranged to
translate
along a predetermined translation path from a first radial position relative
to said
central axis to at least a second radial position relative to said central
axis, such
that said the predetermined translation path for each of said plurality of
driven
members is angularly offset with respect to the predetermined translation path
of at
least one other driven member; and
a transmission output interface configured to transmit a torque output, said
transmission output interface being coupled to said plurality of driven
members and
configured to receive a torque therefrom.
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In such a transmission, a transmission input interface of the transmission
receives
a torque input and is connected to a plurality of drive members which receive
the
torque input from the transmission input interface and which can provide a
large
and potentially infinite number of gear ratios within a range of gear ratios.
The
drive members are engaged with a plurality of driven members that each move
radially along a predetermined path from a first position to a second
position, and
such that each predetermined path is angularly offset with respect to the
predetermined paths of the other driven members. For example, the driven
members may be spaced around a circle and move along straight or curved
predetermined paths that are each offset at equal angular intervals around the
circle. The driven members may further be connected to a transmission output
interface which transmits a torque output of the transmission.
According to a further aspect of the invention, a transmission comprises:
a transmission input interface configured to receive an input torque from a
power source;
one or more drive gears coupled to said transmission input interface, said
one or more drive gears being configured to translate radially;
a plurality of driven gears configured to engage said one or more drive
gears, said plurality of driven gears collectively defining a virtual gear
configured to
maintain engagement with said one or more drive gears at a plurality of gear
ratios,
wherein said virtual gear is configured to change size as said one or more
drive
gears translate radially, wherein different sizes of said virtual gear define
different
respective gear ratios; and
a transmission output interface coupled to said plurality of driven gears,
said
transmission output interface being configured to transmit an output torque,
and
said output torque being related to said input torque by a gear ratio related
to said
size of said virtual gear.
According to another aspect of the invention, a transmission comprises:
a power input interface configured to receive a first torque;
sets of one or more movable drive and driven gears; and
a power output interface coupled to the driven gears and configured to
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transmit a second torque.
In such a transmission, the sets of drive and driven gears have at least one
particular positioning within the transmission that results in the second
torque being
negligible, possibly as low as zero or nearly zero. However, the drive and
driven
gears maintain engagement with each other, even with zero output, such that an
engaged neutral is implemented where the power source remains connected to the
load. In some cases, when the drive gears are at the particular position, the
drive
gears may have rotational and orbital motions which substantially, or
completely,
1o cancel each other out so that while the drive gears may continue to rotate
and orbit,
the motion of the drive gears does not cause any rotation of the driven gears.
The
drive gears may produce an intermediate output torque which is input into a
secondary gear set. The secondary gear set may also receive the input torque
and
place the input torque in conflict with the intermediate output torque to
produce a
final, net output torque. At the particular position of the drive and driven
gears, the
secondary gear set may receive an intermediate output torque which, when
placed
in conflict with the input torque, substantially cancels the input torque such
that the
secondary gear set provides negligible, possibly zero or nearly zero, output
torque.
According to another aspect of the invention, a drive system comprises:
a power source;
a transmission coupled to said power source, said transmission comprising:
a transmission input interface configured to receive an input torque from said
power
source;
one or more drive gears coupled to said transmission input interface, each
of said drive gears being configured to rotate about a respective internal
axis of the
drive gear and for orbital motion about a common axis, wherein said rotational
motion and said orbital motion are caused by receipt of said input torque;
one or more driven gears configured to engage said one or more drive
gears, such that said one or more drive gears are configured and arranged to
cause said one or more driven gears to rotate;
a transmission output interface coupled to said one or more driven gears;
a power train coupled to said transmission output interface of said
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transmission; and
a load coupled to said power train.
In such a drive system, a power source, such as an engine, may be provided. A
transmission may be coupled to the power source to receive an input torque
from
the power source. The transmission may correspondingly include a transmission
input interface for receiving the input torque, one or more drive gears
coupled to
the transmission input interface, and one or more driven gears engaged with
the
drive gears. Each of the drive and driven gears may be adapted to
synchronously,
or near synchronously, translate in a radial direction, while also maintaining
1o substantially constant engagement between the drive and driven gears so as
to
provide a large number of gear ratios within a range of available gear ratios.
The
transmission may also include a transmission output interface coupled to the
driven
gears so that an output torque can be transmitted by the transmission. In this
example, the drive system may also include a drive train coupled to the
transmission output interface of the transmission so as to receive the output
torque.
The drive system may also include a power sink to which some or all of the
output
torque is directed.
Additionally, the present invention also relates to a method for providing
power
transmission. In one example, an input is provided and the input is
transformed
into an output for one or more gear ratios of a range of gear ratios. The
output may
comprise a desired amount of torque. Additionally, or alternatively, the
output may
be zero or nearly zero, notwithstanding that the input is simultaneously being
provided. Further, the one or more gear ratios in connection with which the
output
is provided may comprise a large number of gear ratios which are optionally a
large
number of discrete gear ratios which step between whole integer, virtual
gears.
Brief Description of the Drawings
Examples of the present invention will now be described in detail with
reference to
the accompanying drawings, in which:
Figure 1A is a perspective view of an exemplary positive displacement variable
speed transmission according to one embodiment of the present invention in
which
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multiple drive and driven gears are configured to remain constantly engaged
throughout gear ratio changes which can occur in very small, and possibly non-
discrete, increments;
Figure 1 B is a perspective view of another exemplary variable speed
transmission
according to another embodiment of the present invention, in which multiple
drive
gears and driven gears are configured to engage each other at multiple
discrete
gear ratios which can change in very small, discrete increments;
Figures 2A-2G are front views of the drive and driven gears of the
transmissions of
Figures 1 A and 1 B in various stages of a partial orbital cycle of the drive
gears;
to Figures 3A-3C schematically disclose three gear ratios of an exemplary
positive
displacement, variable speed transmission having three offset ring gears and
two
moon gears, and in which the two moon gears and the three ring gears are each
radially movable to engage each other over a range of very small gear ratio
changes;
Figure 4 schematically discloses the rotational and translational movements of
various drive and driven gears of an exemplary transmission according to one
embodiment of the present invention;
Figure 5 is a perspective view of a carriage for use with the positive
displacement
variable speed transmission of Figures 1A and 1 B, in which the carriage is
adapted
to radially move drive rods so as to radially move drive gears mounted on the
drive
rods;
Figure 6 is a rear view of exemplary linkage and gear track systems for
controlling
radial movement of a ring gear in the transmissions of Figure 1 A and 1 B;
Figure 7 schematically discloses an exemplary control system for controlling a
transmission according to exemplary embodiments of the present invention;
Figure 8 discloses a reference gear and a drive gear which can be used to
synchronize the motions of drive gears such that the drive gears can properly
align
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with driven gears for engagement at a large number of gear ratios and at
various
lever lengths which can change in very small, and possibly infinitely small,
increments;
Figure 9 discloses an exemplary planetary gear set that may be used to obtain
an
engaged neutral if the torque flow path is reversed through the transmissions
of
Figures 1A and 1B;
Figures 1 OA-B disclose various drive and driven gears in alternative
embodiments
of exemplary transmission systems where the radially expandable drive gears
orbit
and alternately engage driven gears which are offset from each other at equal
1o angular intervals around a circle;
Figure 11A is a plan view of an alternative embodiment of a positive
displacement
variable speed transmission in which multiple drive and driven gears are
maintained in constant engagement over a range of very small, and possibly
infinitely small, gear ratio changes;
Figure 11B is a partial cross-sectional view of the transmission of Figure 11A
in
which eight orbiting and rotating drive gears are maintained in constant
engagement with five driven gears;
Figure 12 discloses a set of drive and driven gears in an alternative
embodiment of
exemplary transmission systems, in which the drive and driven gears are
positioned in a dual-plane configuration; and
Figure 13 discloses an exemplary drive system representative of a variety of
applications in which a transmission according to the present invention can be
utilized to transfer power from a power source to a load.
Detailed Description
The present invention provides a transmission capable of operating over a
large, or
possibly infinite, number of gear ratios. The transmission maintains
substantially
constant engagement between at least one drive gear and at least one driven
gear
during gear ratio changes, and can maintain such engagement even while the
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transmission is in a neutral output state. By maintaining a substantially
constant
engagement between at least one drive gear and at least one driven gear, the
transmission is able, when a load is being driven, to implement changes to an
associated gear ratio while simultaneously maintaining the connection of the
power
to the load.
As used herein, the phrase "constant engagement" embraces, but is not limited
to,
substantially continuous engagement between at least one drive gear and at
least
one driven gear which are used to effect changes to the overall gear ratio of
a
transmission, and such that the drive and driven gears have a substantially
to constant mesh. Stated another way, in a constant engagement transmission,
two
or more gears are engaged with each other throughout different gear ratios-and
the changes therebetween-and during the revolutions of the transmission. With
respect to the foregoing however, it will be understood that there is no
requirement
that any particular drive gear always be engaged with any particular driven
gear.
For example, a transmission may operate with "constant engagement" where
various drive gears alternately engage one or more driven gears such that at
least
one of the various drive gears is, at any given time, engaged with one or more
of
the driven gears. The term "constant engagement" also does not require
engagement between gears of any particular material. In fact, constant
engagement may be maintained between gears of any combination of materials
including, by way of example only, metal, composite, wood, or plastics. Where
the
constant engagement is maintained between one or more drive gears and one or
more driven gears which are metal, such that constant metal-to-metal
engagement
is maintained, the engagement may be referred to herein as "positive
displacement."
The phrase "constant velocity" is also used herein to describe an aspect of a
transmission according to some embodiments of the present invention. As used
herein, the term "constant velocity" describes the power transfer from the
input to
the output by means of gear profiling, such as involute gear profiling, and/or
other
means which are non-oscillating.
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The phrase "infinitely variable" is also used herein to describe an aspect of
a
transmission according to some embodiments of the present invention. As used
herein, the term "infinitely variable" embraces, but is not limited to a
transmission
which is capable of operating at a plurality of gear ratios and in which the
plurality
of gear ratios are changeable in very small, possibly infinitely small,
increments
over a range of gear ratios.
As noted above, transmissions having engagement between drive and driven gears
have typically relied on the disconnection of the power source from the load
in
order to effect a change in gear ratio. To overcome the difficulties that
arise with
1o such a disconnection, various belt drive, friction shifting, or other
methods of
maintaining torque have been developed. However, no such designs have allowed
an engine to maintain a high level of torque through a gear change,
particularly
while operating at a constant velocity and while maintaining constant
engagement,
or at least near constant engagement, between gear teeth so as to main
constant,
or near constant, connection between the power source and the drive and driven
gears.
Accordingly, in high torque applications, transmissions commonly employ
multiple
gears to provide a ratio change. For example, one or more drive gears of
differing
sizes can be used to drive one or more driven gears of differing sizes. To
change
between gear ratios, the transmission disengages a drive gear from a driven
gear
and then re-engages the same or a different drive gear with another driven
gear.
The gear ratio is changed inasmuch as the newly engaged drive clear and/or
driven
gear has a smaller or larger diameter than the previously engaged gears such
that
the radius-also referred to as the lever-of one engaged gear changes in
relation
to the radius of another engaged gear.
For example, before a change in gear ratios, the engaged drive and driven
gears
may operate at a gear ratio of, for example, 4:1. For such a gear ratio, the
radius
of an engaged driven gear may be four times larger than the radius of the
engaged
drive gear such that it requires four complete rotations of the drive gear to
effect a
single rotation of the driven gear. To cause a gear ratio change, the drive
gear
may be removed from engagement with the driven gear and engaged with a
16
CA 02736815 2011-04-14
different driven gear of a size which differs from the previously engaged
driven
gear. As the size of the newly engaged driven gear increases or decreases, the
associated gear ratio is correspondingly increased or decreased. As can be
seen,
multiple driven and/or drive gears are thus useful to change between gear
ratios
within a range of discrete gear ratios.
Figure 1A discloses aspects of an exemplary embodiment of a transmission 100
which can maintain constant engagement during gear ratio changes, and which
can change between gear ratios in very small increments, and possibly in
infinitely
small or substantially non-discrete increments. It should be appreciated that
the
io illustrated embodiment is merely an exemplary embodiment and is presented
for
illustrative purposes, and should therefore not be considering limiting of the
present
invention.
In the illustrated embodiment, transmission 100 includes a transmission input
interface 105 which can be connected to an external power source.
Additionally,
transmission input interface 105 may be connected to a power transfer system
110
within transmission 100, such that transmission input interface 105 can
transmit
power input from the external source to power transfer system 110. Power
transfer
system 110, in turn, may transfer the input power to a power output system 130
of
transmission 100. As disclosed in more detail herein, power transfer system
110
and power output system 1.30 can be coupled such that a variety of gear ratios
associated with transmission 100 can be obtained by synchronizing power
transfer
system 110 and power output system 130 such that during gear ratio changes,
power transfer system 110 maintains substantially constant engagement with
power output system 130. Moreover, inasmuch as power transfer system 110 and
power output system 130 maintain substantially constant engagement while
changing gear ratios, power transfer system 110 and power output system 130
collectively operate as a variable power transform system 135 which maintains
substantially constant engagement during gear ratio changes which can be
effected in small, and possibly infinitely small, increments.
3o As disclosed herein, transmission input interface 105 may be adapted to be
coupled to a power supply. For example, transmission input interface 105 may
be
17
CA 02736815 2011-04-14
coupled to a power supply that is external to transmission 100. By way of
example,
transmission input interface 105 may receive power input directly or
indirectly from
a drive shaft or other rotating shaft that is rotated by an engine. Such
engines may
be employed in connection with a variety of different vehicles, aircraft and
marine
craft. In another embodiment, and by way of example only, transmission input
interface 105 may be connected to a power supply in a conveyor system, a
windmill, a hydroelectric power generation system, an elevator, or in any
other
suitable application. Moreover, use of transmission 100 with a power supply in
a
motor vehicle may include, by way of example and not limitation, passenger
io vehicles, transport vehicles, construction equipment, racing vehicles, all-
terrain
vehicles, military vehicles and equipment, marine vehicles, aircraft, and
agricultural
vehicles and equipment.
In the illustrated embodiment, transmission input interface 105 is coupled to
power
transfer system 110 such that as power is received by transmission input
interface
105, the received power is transferred to and through power transfer system
110 to
power output system 130. In the illustrated embodiment, power transfer system
includes a carrier arm 112 which is connected to transmission input interface
105
and which rotates as a power input is received by transmission input interface
105.
As will be appreciated in light of the disclosure herein, as a power input is
received,
transmission input interface 105 may cause carrier arm 112 to rotate in unison
therewith such that for each complete rotation of transmission input 105,
carrier
arm 112 makes a corresponding complete rotation. In other embodiments,
however, it will be appreciated that carrier arm 112 may be coupled to
transmission
input interface 105 such that carrier arm 112 rotates at a different angular
velocity
than transmission input interface 105, such that carrier arm 112 may rotate at
a
greater or lesser speed than transmission input interface 105.
As illustrated, carrier arm 112 may be also coupled to one or more ratio
reference
gears 114. Ratio reference gears 114 are, in this embodiment, coupled to
carrier
arm 112 such that as carrier arm 112 rotates, ratio reference gears 114 also
orbit
around the center of carrier arm 112. Through the orbital motion, ratio
reference
gears 114 engage and roll around a reference gear 116, and the ratio reference
18
CA 02736815 2011-04-14
gears 114 also simultaneously rotate about their respective central axes.
While
two ratio reference gears 114 and a single reference gear 116 are illustrated,
it will
be appreciated that this arrangement is illustrative only and that in other
embodiments, more or fewer ratio reference gears 114 and/or reference gears
116
may be used.
As illustrated in Figure 1A, ratio reference gears 114 are, in some
embodiments,
coupled to a set of transfer gears 118a-d which transmit the input power
received
by transmission input interface 105 to one or more drive gear sets 120a-b. In
the
embodiment illustrated in Figure 1A, for example, ratio reference gears 114
are
io coupled to a series of transfer gears 11 8a-d which rotate in a one-to-one
ratio with
ratio reference gear 114, such that for each complete rotation of ratio
reference
gears 114, each of transfer gears 118a-d also have a single, complete
rotation. In
particular, in the illustrated embodiment, each ratio reference gear 114 is
coupled
to a shaft 114a. Shaft 114a passes through carrier arm 112 and is further
connected to a transfer gear 118a, such that as ratio reference gears 114
rotate,
shafts 1 14a and transfer gears 118a each maintain the same rotational speed.
To
allow rotation of shafts 114a within carrier arm 112, it will be appreciated
that
carrier arm 112 may also be journaled and include, for example, bearings or
bushings which allow shafts 114a to rotate within carrier arm 112. Although
the
illustrated embodiment discloses a one-to-one ratio between ratio reference
gears
114 and transfer gear 118a, it should be appreciated that this ratio is only
one
example, and that one or more of transfer gears 118a-d can rotate at different
ratios with respect to ratio reference gears 114.
Transfer gears 118a can also be coupled to second transfer gears 118b which
maintain the same or different RPMs. In the illustrated embodiment, for
example,
transfer gears 118a-b are shown as bevel gears of the same sizes, although it
will
be appreciated that a variety of sizes and types of gears, or other systems
for
transferring power, may be used. For example, in other embodiments, one or
more
of transfer gears 118a-b may be spur gears, worm gears, helical gears, or any
other suitable type of gear.
In transmission 100, transfer gears 118b can further be coupled to transfer
gears
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CA 02736815 2011-12-22
118c-d which are configured to transfer power to drive gear sets 120a-b. For
example, in the illustrated embodiment, transfer gears 118a-b are indirectly
coupled to drive gear sets 120a-b by transfer shaft 122. In particular,
transfer gear
11 8b is coupled to transfer shaft 122 such that transfer shaft 122 rotates as
transfer
gears 118b are rotated by transfer gears 118a. In power transfer system 110,
transfer gears 118c may further be coupled to transfer shaft 122 such that
transfer
gears 118c also rotate as transfer shaft 122 and transfer gears 118b rotate.
Moreover, transfer gears 11 8c can mate with and engage transfer gears 11 8d
such
that transfer gears 118d are rotated by transfer gears 118c. Consequently,
io inasmuch as transfer gears 118a are coupled to ratio reference gears 114a
and
further at least indirectly to each of transfer gears 118b-d, as ratio
reference gears
114 rotate, each of transfer gears 118a-d can also rotate. As will be
disclosed in
greater detail hereafter, in some embodiments, transfer gears 118c-d may
further
be configured to be movable along transfer shaft 122.
Further, according to some example embodiments, transfer shaft 122 may be
coupled to carrier arm 112, such that it is housed within carrier arm 112
while it
rotates. In the illustrated embodiment, for example, ends of transfer shaft
122
extend into carrier arm where they are journaled with one or more bearings,
bushings or other suitable devices such that they can freely rotate, but
wherein
they are also substantially fixed to prevent significant axial movement of
transfer
shaft 122. In other examples, however, transfer shaft 122 may be adapted to
rotate and move axially such that the illustrated embodiment is only one
example of
transfer shaft 122 and is not limiting of the present invention.
In the illustrated embodiment, power transfer system 110 also includes drive
rods
124a-b. Drive rods 124a-b are, in this embodiment, used to rotate respective
drive
gear sets 120a-b which each comprise one or more of drive gears 121a-f. In the
illustrated embodiment, for example, drive rods 124a-b are coupled to
respective
transfer gears 11 8d such that as transfer gears 11 8d rotate, drive rods 124a-
b also
rotate, thereby also rotating drive gears 121a-f of drive gear sets 120a-b.
3o As disclosed herein and as further illustrated in the example embodiment of
Figure
1A, each of drive gear sets 120a-b can include one or more drive gears 121a-f.
In
CA 02736815 2011-04-14
the illustrated embodiment, for example, each drive gear set 120a-b includes
three
drive gears coupled thereto, although more or fewer drive gears may be
employed
in one or more drive gear sets. In particular, in the illustrated embodiment,
drive
gear set 120a includes drive gears 121 a-c, and drive gear set 120b includes
drive
gears 121 d-f.
As illustrated, one or more of drive gears 121a-f may further engage power
output
system 130 so as to transfer the power from power transfer system 110 to power
output system 130. In the illustrated embodiment, for example, power output
system 130 includes a plurality of driven gears 132a-c which are, in this
io embodiment, ring gears, and which are each engaged by one or more of drive
gears 121a-f. In the illustrated embodiment, for example, drive gear 121f is
currently engaged with driven gear 132c.
As disclosed herein, when transmission input interface 105 receives power from
a
power source, transmission input interface 105 may cause carrier arm 112 to
rotate. For example, in the illustrated embodiment, carrier arm 112 is rotated
about
a central axis that is substantially coaxial with a central axis of
transmission input
interface 105, although in other embodiments, carrier arm 112 may rotate about
an
axis that is not coaxial with the central axis of transmission input interface
105.
Further, carrier arm 112 is, in some embodiments, coupled to drive rods 124a-
b.
For example, in the illustrated embodiment, and as disclosed herein, ratio
reference gears 114, transfer gears 11 8a-d and/or transfer shaft 122 may
couple
drive rods 124a-b to carrier arm 112 in a manner that causes drive rods 124a-b
to
rotate about their respective central axes as carrier arm 112 is rotated about
its
central axis. In this manner, as transmission input interface 105 receives a
power
input, carrier arm 112, drive rods 124a-b and drive gears 121a-f each rotate
about
their respective central axes.
In addition, in the illustrated embodiment, drive rods 124a-b are further
coupled to
carrier arm 112 such that as carrier arm 112 rotates about its central axis,
drive
rods 124a-b follow a similar path and collectively orbit around the central
axis of
carrier arm 112. Thus, as transmission input interface 105 rotates, drive rods
124a-b, and drive gears 121a-f connected to drive rods 124a-b, each have a
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CA 02736815 2011-04-14
rotational motion about their respective, central axes, and further have an
orbital
motion around the central axis of carrier arm 112. In example embodiments in
which drive gears 121 a-f are fixed on drive rods 124a-b so as to maintain the
same
rotational speed as drive rods 124a-b, it will also be appreciated that drive
gears
121a-f can thus have both rotational and orbital motions, about different
respective
axes, and accordingly, may be referred to herein as moon gears.
As drive gears 121a-f rotate and orbit, they engage driven gears 132a-c of
power
output system 130, thereby transferring power to power output system 130.
Moreover, as disclosed herein, power transfer system 110 of Figure 1A may
in operate without clutches or bands being used to change between gear ratios,
or
may otherwise be configured to be substantially constantly connected to an
external power source in communication with transmission input interface 105.
For
example, in some embodiments, each of drive gears 121a-f acts as a moon gear
and rotates and orbits within the interior of one of driven gears '132a-c,
which are
ring gears. Inasmuch as drive gears 121a-f collectively remain in
substantially
constant connection with transmission input interface 105 as transmission
input
interface 105 receives a power input, drive gears 121 a-f each rotate and
orbit.
Moreover, power output system 130 can be configured to be in constant
engagement with at least one of drive gears 121 a-f at any particular gear
ratio, or
even possibly during changes between gear ratios, as disclosed herein. For
example, as drive gears 121 a-f orbit and rotate, at least one of drive gears
121a-f
can always be engaged with at least one of driven gears 132a-c of power output
system 130. Thus, inasmuch as at least one driven gear 132a-c is always
engaged
with at least one drive gear 121 a-f, and at least one of drive gears 121a-f
is always
engaged with the power source, at least one driven gear 132a-c is thus
constantly
connected to the power source. Moreover, in some embodiments, and as
disclosed in more detail herein, driven gears 132a-c can be linked such that
as any
one or more of driven gears 132a-c is engaged and rotated by drive gears 121 a-
f,
such that the engaged one or more of driven gears 132a-c rotate about their
3o respective central axes, all of driven gears 132a-c synchronously rotate
about their
own respective central axes. In this manner, if any one of driven gears 132a-c
is
22
CA 02736815 2011-04-14
engaged by a drive gear 121a-f, and is thus connected to the power source,
each
of driven gears 132a-c is also connected to the power source and rotates as
well.
To maintain substantially constant engagement between one or more of drive
gears 121a-f and one or more driven gears 132a-c, driven gears 132a-c may be
configured to alternately engage drive gears 121a-f in a manner such that at
least
one of drive gears 121 a-f is always in engagement with at least one of driven
gears
132a-c. Figures 2A-G illustrate, for example, driven gears 132a-c and drive
gear
sets 120a-b in transmission 100 of Figure 1A as viewed from a frontal
perspective
taken from proximal end 101 of transmission 100. Specifically, Figures 2A-G
io illustrate drive gear sets 120a-b at various stages of a particular orbital
cycle of
drive gears 121a-f of drive gear sets 120a-b, and disclose one manner in which
constant engagement between power output system 130 and power transfer
system 110 can be maintained. As illustrated in Figure 2A, for example, driven
gears 132a-c can, in some embodiments, be offset such that they rotate around
offset central axes. For example, in the illustrated embodiment, driven gears
132a-
c are offset and driven gear 132a rotates around a central axis passing
through
center 132a', driven gear 132b rotates around its central axis passing through
center 132b', and driven gear 132c rotates around its central axis passing
through
center 132c'.
In the illustrated embodiment, driven gears 132a-c are offset around a circle
at one
hundred twenty degree intervals. In particular, it can be seen that if a
circle is
drawn to circumscribe an equilateral triangle formed by centers 132a'-c',
lines
passing through the center of the circumscribing circle and each of centers
132a'-c'
are each offset one hundred twenty degrees. It should be appreciated, however,
that this offset is exemplary only and not limiting of the present invention.
For
example, in some other embodiments, more or fewer than three ring gears can be
used, and each ring gear can be offset at equal intervals other than one
hundred
twenty degrees. In other embodiments, unequal angular offsets are used,
regardless of the number of output gears. In still other embodiments, multiple
driven gears can rotate about a common axis.
As shown in Figure 2A, when three driven gears 132a-c are offset at equal
angular
23
CA 02736815 2011-04-14
intervals of one hundred twenty degrees, a rounded triangular portion is
formed
which is common to each of driven gears 132a-c, and which has one side formed
by each of driven gears 132a-c. Within this common area, drive gear sets 120a-
b
can orbit and rotate, and individually enter into and out of engagement with
driven
gears 132a-c, while collectively maintaining engagement with driven gears 132a-
c.
In this embodiment, for example, drive gear sets 120a-b are offset around a
circle
at one hundred eighty degrees. However, in other embodiments more or fewer
than two drive gear sets may be used, and/or the drive gears or drive gear
sets
may be spaced at different angular intervals.
io As shown in Figure 1A, each of drive gear sets 120a-b may have at least one
drive
gear 121a-f corresponding to each driven gear 132a-c. For example, in Figure
1A,
drive gears 121 a and 121 d lie in the same plane as, and engage, driven gear
132a.
Similarly, drive gears 121b and 121e lie in the same plane as, and engage,
driven
gear 132b, while drive gears 121c and 121f are similarly disposed with respect
to
driven gear 1 32c. In other embodiments, more or fewer drive gears are used.
For
example, a single gear may replace a set of two or more drive gears. For
example,
a single drive gear may be sized such that it extends through the planes of
each of
driven gears 132a-c, thereby allowing it to engage each of driven gears 132a-
c.
Alternatively, a drive gear may be adapted to move axially so as to move
between
the respective planes of each of driven gears 132a-c and engage each of driven
gears 132a-c. Accordingly, a drive gear set may include as few as one drive
gear.
Returning now to Figure 2A, it can be seen that drive gear sets 120a-b may
orbit
within the common area of driven gears 132a-c and around an axis that is
offset
from the center of one or more of driven gears 132a-c. For example, drive gear
sets 120a-b may collectively orbit around an axis passing through center point
120'
which is not aligned with any of center points 132a'-c' about which driven
gears
132a-c rotate. As drive gear sets 120a-b rotate in this common area, they may
alternately engage the three curved sides of the common area. As is evident
from
Figure 2A at least, each of the three curved sides of the common area is the
interior profile of one of the respective driven ring gears 132a-c. In this
manner, the
gear teeth of virtual output gear 132 comprise gear teeth from each of driven
ring
24
CA 02736815 2011-04-14
gears 132a-c. Thus, the driven gears 132a-c collectively define a virtual
output
gear 134 which is constantly engaged and driven by drive gear sets 120a-b at a
particular gear ratio. Moreover, the configuration of virtual gear 134 can
change
from one gear ratio to another. For instance, the size of virtual gear 134 can
change as driven gears 132a-c move inward or outward. As is evident, if the
gear
teeth of driven gears 132a-c remain a constant size, the number of virtual
gear
teeth on virtual output gear 134 can therefore also change as virtual output
gear
134 changes size. In the example of Figure 2A, the virtual gear includes gear
teeth
from each of the three different driven gears, and each driven gear defines
1o approximately one-third of the virtual output gear, although the use of
more or
fewer driven gears can result in corresponding changes to the number of gear
teeth
contributed by each driven gear, as well as to the percentage contribution of
each
driven gear. As further disclosed herein, virtual output gear '134 may also be
substantially constantly engaged by drive gear sets 120a-b during changes
between gear ratios.
An exemplary manner in which drive gear sets 120a-b can selectively engage
driven gears 132a-c, and thereby also engage effective output gear 134 formed
by
driven gears .132a-c, is illustrated in Figures 2A-G, which illustrate various
stages of
a half orbit of drive gear sets 120a-b around center 120'. In Figure 2A, for
example,
drive gear sets 120a-b are aligned in the vertical direction, at zero degrees
and
one-hundred eighty degrees, respectively. In this position, one or more drive
gears
from drive gear set 120b may be in dead center engagement with driven gear
132c,
while any drive gears in drive gear set 120a are fully disengaged from any of
driven
gears 132a-c. It should be appreciated in light of the disclosure herein that
while
the embodiment illustrated in Figure 2A shows drive gear set 120b in
engagement
with driven gear 132c, it is not required that each gear in drive gear set
120b be
simultaneously engaged. In fact, drive gear set 120b can be engaged when any
one or more of drive gears 121d-f of that drive gear set 120t> is engaged. As
illustrated in the example arrangement of Figure 1A, for example, drive gear
set
120b is engaged with driven gear 132c even when only drive gear 121f is
engaged
with ring gear 132c.
CA 02736815 2011-04-14
As drive gear sets 120a-b orbit around a central axis passing through center
120',
they can maintain engagement with virtual gear 134 by alternately engaging
driven
gears 132a-c. For example, Figure 2B illustrates drive gear sets 120a-b after
they
orbit clockwise thirty degrees from the position in Figure 2A. As illustrated,
throughout the thirty degrees of clockwise rotation, drive gear set 120b
maintains
engagement with driven gear 132c. In addition, at thirty degrees rotation,
drive
gear set 120b is preparing to begin disengagement from driven gear 132c.
However, at about the same time, drive gear set 120a is entering into
engagement
with driven gear 132b. For example, drive gear 121b (Figure 1A) may be
entering
io into engagement with driven gear 132b.
If drive gear sets 120a-b orbit another thirty degrees in a clockwise
direction, drive
gear sets 120a-b move to a position such as that illustrated in Figure 2C. As
illustrated in Figure 2C, drive gear set 120a has now moved into dead center
engagement with driven gear 132b, while drive gear set 120b has completely
disengaged from effective output gear 134. Dead center engagement can occur in
an involute gear profile where, for example, an engaging gear tooth is
substantially
centered within a root of the mating gear.
As further illustrated in Figure 2D, with another thirty degrees clockwise
orbit
around center 120', each of drive gear sets 120a-b again become engaged with
virtual gear 134. For instance, drive gear set 120a maintains engagement with
driven gear 132b as drive gear set 120b engages driven gear 132a. In one
exemplary embodiment, drive gear 121d (Figure 1) of drive gear set 120b thus
engages driven gear 132a. Thereafter, with another thirty degrees clockwise
orbit,
and as illustrated in Figure 2E, drive gear set 120b may enter into dead
center
engagement with driven gear 132a as drive gear set 120a is disengaged from
virtual gear 134.
Similar engagement is maintained throughout a continued orbit by drive gear
sets
120a-b, as illustrated in Figures 2F-G. In particular, with an additional
thirty
degrees clockwise orbit about center 120' drive gear sets 120a-b can be
positioned
as illustrated in Figure 2F, in which drive gear set 120b maintains engagement
with
driven gear 132a as drive gear set 120a enters into engagement with driven
gear
26
CA 02736815 2011-04-14
132c. In one example, drive gear 121c (Figure 1A) of drive gear set 120a
enters
into engagement with driven gear 132c. Thereafter, an additional thirty
degrees
clockwise orbit of drive gear sets 120a-b, for a total of one hundred eighty
degrees
rotation from the position of Figure 2A, may result in a position similar to
that
illustrated in Figure 2G in which drive gear set 120a is in dead center
engagement
with driven gear 132c and gear set 120b is disengaged from each of driven
gears
132a-c.
Thereafter, rotation of drive gear sets 120a-b may continue to complete a full
rotation in a manner similar to that illustrated in Figures 2A-G, except that
the
io opposite drive gear sets now alternately engage virtual gear 134. In
particular,
actions of drive gear set 120a in Figures 2A-G would be replaced by the
actions of
drive gear set 120b, and the actions of drive gear set 120b would be replaced
by
those of drive gear set 120a. Accordingly, drive gear sets 120a-b collectively
maintain engagement with virtual output gear 134 as they orbit around an axis
passing through center 120'. Moreover, it can be seen that in some
embodiments,
driven gears 132a-c are alternately engaged by drive gear sets 120a-b and that
drive gear sets 120a-b and drive gears 121a-f may also alternately engage
driven
gears 132a-c and virtual output gear 134 such that at least one of drive gears
121a-f is always engaged with at least one of driven gears 132a-c. Moreover,
in
embodiments in which driven gears 132a-c are linked to each other to maintain
synchronous rotations, engagement of any one of one driven gear 132a-c can
result in a corresponding rotation of each of driven gears 132a-c, such that
all
driven gears 132a-c remain connected to drive gear sets 120a-b and the power
source.
Although Figures 2A-G illustrate a partial orbital cycle of drive gear sets
120a-b in a
clockwise direction, and rotation of drive gears 121a-f about their respective
centers in a counterclockwise direction, it should be appreciated that a
transmission according to the present invention is not limited to any
particular
orbital direction, and that, in other embodiments, drive gear sets 120a-b
orbit
around an axis passing through center 120' or some other reference point in a
counterclockwise or other direction. For example, an exemplary illustration of
an
27
CA 02736815 2011-04-14
orbital cycle of drive gear sets 120a-b in a counterclockwise direction can be
seen
by reversing the order of the cycle illustrated in Figures 2A-G. Moreover,
while the
illustrated embodiment discloses that one drive gear set is disengaged while
the
other is engaged in dead center engagement, it should also be appreciated that
this arrangement is illustrative only and not limiting of the present
invention. For
example, it is contemplated that in other embodiments one or more drive gear
sets
are engaged with one or more driven gears at the same time as the same or
another drive gear set is in dead center engagement with another driven gear.
As drive gear sets 120a-b engage virtual gear 134 by, for example, alternately
io engaging driven gears 132a-c as drive gear sets 120a-b follow an orbital
path,
drive gear sets 120a-b cause driven gears 132a-c to rotate. This is because,
as
noted earlier, drive gears 121a-f of drive gear sets 120a-b can rotate as well
as
orbit. For example, each driven gear can be caused to rotate around its own
central axis. Returning now to Figure 1A, it can be seen that in some
embodiments, output driven gears 132a-c can be linked together such that they
maintain identical rotations while each rotates about its own central axis. In
the
illustrated embodiment, for instance, power output system 130 includes a
linkage
system 136 for each driven gear 132a-c. In general, linkage systems 136 link
the
rotation of each driven gear to the rotation of each of the other driven
gears. In this
manner, as one driven gear rotates, the other driven gears each have
corresponding, synchronous rotations about their own central axes.
According to one example embodiment of the present invention, each linkage
system 136 may include an output moon gear 138 which engages one of driven
gears 132a-c. In the illustrated embodiment, drive gears 121a-f each have a
gear
tooth profile that mates with a gear tooth profile on the interior of driven
gears
132a-c, such that as drive gears 121a-f rotate and/or orbit, driven gears 132a-
c are
caused to rotate. Further, driven gears 132a-c may also have an exterior gear
tooth profile which mates with a gear tooth profile of output moon gears 138.
In this
manner, and by way of example only, as drive gears 121a-f engage and drive
3o driven gears 132a-c, driven gears 132a-c cause output moon gears 138 of
linkage
systems 136 to rotate and thereby transfer power to output moon gears 138 of
28
CA 02736815 2011-12-22
linkage systems 136.
Linkage systems 136 may further include an output sun gear 140 which mates
with
output moon gear 138. As illustrated in Figure 1A, for example, output moon
gears
138 are elongated such that they can engage a driven gear 132a-c and an output
sun gear 140. In other embodiments, however, output moon gear 138 can be
separated into different portions which are then connected such that a first
gear
engages a driven gear 132a-c and a second gear engages output sun gear 140.
Inasmuch as output moon gear 138 mates with output sun gear 140, as output
moon gear 138 rotates, the gear teeth on output moon gear 138 engage the gear
1o teeth on output sun gear 140, thereby also causing output sun gear 140 to
rotate.
In some embodiments, linkage system 136 further includes a linkage shaft 142
which is connected to output sun gear 140 on a distal end of linkage shaft
142. In
some embodiments, linkage shaft 142 is also connected to an output transfer
gear
145 on a proximal end. Linkage shaft 142, output sun gear 140, and output
transfer gear 145 are, in some embodiments, adapted to maintain the same rate
of
rotation. For example, linkage shaft 142 can be connected to output sun gear
140
and output transfer gear 145 such that as output sun gear 140 rotates, output
transfer gear 145 is also rotated. Optionally, output transfer gear 145 is
rotated at
the same speed as output sun gear 140.
In some example embodiments, transmission 100 may further include elements for
connecting linking systems 136 of each driven gear 132a-c in output system
130,
such that the output of any one of linkage systems 136 rotates, e.g. by
rotating
output sun gear 140, the outputs of all other linkage systems 136 have
identical,
synchronous rotations about their respective axes. In the illustrated
embodiment,
for example, transmission 100 includes an output gear 146 which engages each
output transfer gear 145 of each linkage system 136. In this manner, when any
of
driven gears 132a-c is rotated, the linkage system 136 corresponding to the
engaged and rotating driven gear engages output gear 146 and causes output
gear
146 to rotate. As each output transfer gear 145 of each linkage system 136 is
3o engaged with output gear 146, if any one of output transfer gears 145
rotates,
output gear 146 is engaged and rotated, and further causes a corresponding
29
CA 02736815 2011-04-14
rotation of every other output transfer gear. In this manner, rotation of one
or more
of driven gears 132a-c can transfer the power through its corresponding
linkage
system 136, to output gear 146, which then causes linkage systems 136 of
unengaged gears to synchronously rotate the unengaged gears in a rotation that
is
identical to, and corresponds with, the rotation of the one or more engaged
driven
gears. Thus, it can be seen that the connection of any one of driven gears
132a-c
to the power source-such as through engagement with one or more of drive gears
121 a-c--can result in each of driven gears 132a-c being connected to the
power
source.
to To provide power output from transmission 100, transmission 100 can also
include
a transmission output interface 170 which can be then be connected to a drive
train, a load, or a power sink so as to transmit an output power to the drive
train,
load, or power sink. In the illustrated embodiment, transmission output
interface
170 is connected to the linkage system 136 corresponding to driven gear 132b,
although this arrangement is not limiting of the present invention. When
transmission output interface 170 is arranged as illustrated in Figure 1, as
driven
gear 132b is engaged by one or more of drive gear sets 120a-b, or is otherwise
caused to rotate, linkage system 136 also rotates, thereby rotating
transmission
output interface 170 and transmitting a power output. As will be appreciated
from
this disclosure, transmission output interface 170 can also provide a power
output
when driven gear 132b is not directly engaged by drive gear sets 120a-b. For
example, when driven gear 132a or 132c is engaged, linkage systems 136 and
output gear 146 can cause the linkage system 136 corresponding to output
driven
gear 132b to rotate, thereby also providing power output to transmission
output
interface 170.
While Figure 1A illustrates transmission output interface 170 as being
directly
connected to a distal end of the linkage system 136 associated with driven
gear
132b, it should also be appreciated that this arrangement is exemplary only.
In
other embodiments, transmission output interface 170 can be directly connected
to
any other of linkage systems 136. In still other example embodiments,
transmission output interface 170 is not directly connected to any of linkage
CA 02736815 2011-04-14
systems 136. For example, transmission output interface 170 may instead be
directly connected to any one or more of driven gears 132a-c or to output gear
146,
or indirectly coupled in any suitable manner to any of linkage systems 136,
output
gear 146, or driven gears 132a-c.
In some embodiments, each of drive gears 121a-f is the same physical size.
Moreover, each of output driven gears 132a-c, may also be of the same physical
size such that the relationship of the radii of a drive gear 121 a, f to an
engaged
driven gear 132a-c does not change, regardless of which of drive gears 121a-f
engages a driven gear 132a-c. Consequently, and as disclosed in more detail
io herein, transmission 100 can operate at a large number of gear ratios
without
selectively engaging and disengaging physical gears of differing sizes, and
without
clutches and bands. Thus, transmission 100 can act as a clutchless
transmission
inasmuch as it can operate without clutches or bands to engage and disengage
drive or driven gears to effectuate a gear ratio change. Accordingly,
transmission
100 is clutchless inasmuch as it can operate without clutches or bands on the
drive
and driven gears and/or to change gear ratios, regardless of whether clutches
or
bands are otherwise used in transmission 100. In one example embodiment of
transmission 100, however, transmission 100 uses no clutches or bands for any
purpose.
While embodiments of the present invention can extend to a clutchless
transmission in which drive gears 121a-f collectively maintain constant
engagement
with one or more of driven gears 132a-c, even during gear ratio changes, a
clutchless configuration is not necessary in all embodiments of the present
invention. In particular, in some applications it may be desirable that a
clutch or
other mechanism be used to at least temporarily disengage the drive and driven
gears such that the power source is disconnected from the load. Even in such
embodiments, it will be appreciated, however, that embodiments of the
invention
can include aspects such as, for example, the ability to change between a very
large, and possibly an infinitely large, number of non-discrete gear ratios.
Such
3o embodiments of the invention can also include the ability to switch between
gear
ratios in a very small amount of time, such that if the drive and driven gears
are
31
CA 02736815 2011-04-14
temporarily disconnected from each other, such disconnection has a negligible
effect on the momentum of an associated load, and causes little to no torque
spike.
As illustrated in Figure 1 B, for example, an alternative embodiment of a
variable
speed transmission 100' is disclosed in which one or more clutches 123 can be
used in connection with drive gears 121 a-f. It will be appreciated that the
illustrated
embodiment is exemplary only and that clutches of any suitable type and
placement may be used in connection with a transmission according to the
present
invention.
In the embodiment illustrated in Figure 113, at least one clutch 123 is
located on
1o each of drive shafts 124a-b. For example, on drive shaft 124a, a clutch 123
may
be positioned between drive gear 121a and transfer gear 118d, and configured
to
stop the rotation of drive gear 121: Specifically, as input shaft 105 rotates,
thereby
causing drive shafts 124a-b to rotate and orbit, the clutch 123 may be
engaged.
Engagement of the clutch may, in turn, decouple drive gear 121a from the
rotation
of input shaft 105, thereby stopping the rotational motion of drive gear 121a.
As
will be appreciated, due to the placement of clutch 123 between drive gear 121
a
and transfer gear 118, when clutch 123 is engaged and thereby prevents the
rotational motion of drive gear 121a, the rotational motion of drive gears
121b-c is
also stopped.
As further shown in Figure 1 B, a clutch 123 may be similarly located on drive
shaft
124b, between drive gear 121d and transfer gear 118d. Accordingly, when such a
clutch is engaged, thereby decoupling drive gear 121d from the rotation of
input
shaft 105, drive gears 121d-f each cease to rotate. As will be appreciated in
view
of the disclosure herein, any other clutch arrangement that affords comparable
functionality can be employed. The scope of the present invention is not,
therefore,
limited to the illustrative embodiments, and other clutch configurations,
including
the number of clutches, types of clutches, location of clutches, and the like
may be
varied. Additionally, a suitable clutch may provide additional functionality,
such as
moving a drive or driven gear so as to disengage the drive and driven gears.
Moreover, the one or more clutches 123 can be controlled in any suitable
manner.
For instance, a manual or electronic control may be utilized. Accordingly, the
32
CA 02736815 2011-04-14
clutch can, in one example embodiment, be operated and controlled by a
transmission control system, such as electronic control system 180 (Figure 7),
disclosed herein.
As noted above, one or more clutches 123 may be placed in any suitable
location
which allows the clutch(es) to decouple drive gears 121 a-f from the rotation
of input
shaft 105. For example, while a clutch 123 may be positioned as disclosed
above,
namely between transfer gear 118a and drive gears 121 a, d, a clutch 123 may
alternatively, or additionally, be placed in other locations on drive shafts
124a-b.
Illustrated in phantom lines, for example, are alternative or additional
placements
io for clutches 123. Specifically, on drive shaft 124a, one or more clutches
123 can
be placed between drive gear 121a and drive gear 121b, and/or between drive
gear 121b and drive gear 121c. Similarly, one or more clutches 123 can also be
placed on drive shaft 124b between drive gear 121 d and drive gear 121 a
and/or
between drive gear 121e and drive gear 121f.
While the illustrated clutches 123 are illustrated as being located on drive
shafts
124a-b, use of a clutch in this manner is not limited to such positioning.
Indeed, in
some embodiments, it may be desirable to stop both the orbital and rotational
motions of drive gears 121 a-f. Accordingly, a clutch may additionally, or
alternatively, be used to stop the orbital motion of drive gears 121 a-f. By
way of
example and not limitation, a clutch (not shown) may be placed between input
shaft 105 and carrier arm 112. When such a clutch is disengaged, rotation of
input
shaft 105 will continue to cause carrier arm 112 to rotate as described above
with
reference to Figure 1A. However, when such a clutch is disengaged, rotation of
input shaft 105 is decoupled from carrier arm 112, such that carrier arm 112
can
cease to orbit. As will be appreciated in view of the disclosure herein, by
stopping
the orbital motion of carrier 112, the rotational and orbital motions of drive
gears
121a-f can also be stopped, and thus be decoupled from the rotation of input
shaft
105.
The one or more clutches 123 may also be implemented in various other manners.
For example, in one embodiment, one or more clutches may be consolidated at
the
end of drive shafts 124a-b. In such an embodiment, the shafts may be arranged
to
33
CA 02736815 2011-04-14
have a shaft within a shaft arrangement, such that a single clutch can control
engagement and/or rotation of each of drive gears 121 a-f.
As will be appreciated in view of the disclosure herein, clutches 123 may be
of a
variety of different types which are suitable for coupling and decoupling the
rotational and/or orbital motion of drive gears 121 a-f from the rotation of
input shaft
105, and/or engaging and disengaging drive gears 121a-f from driven gears 132a-
c. For example, a clutch 123 may be implemented in various ways, including,
but
not limited to, disc clutch, a cone clutch, a jaw clutch, a claw clutch, a
spiral claw
clutch, a ratchet clutch, a combined conical-disc clutch, a magnetic clutch, a
io hydraulic clutch, or a centrifugal clutch, as desired for a particular
application.
Moreover, it will be appreciated that clutches 123 can be positioned such that
drive
gears 121a-f are implemented within the clutch. For instance, drive gears 121
a-f
may be positioned within a clutch packet, such that clutches 123 are
essentially
aligned with driven gears 132a-c.
Further, while the above disclosure of transmission 100' includes the use of
one or
more clutches 123 to selectively and temporarily disengage drive gears 121 a-f
from
driven gears 132a-c, it should be appreciated that this disclosure is
exemplary only.
In other embodiments, for instance, a window of time can be defined for re-
orienting drive gears 121 a-f, and the orientation of drive gears 121a-f
determined
so as to maintain engagement with driven gears 132a-c for that window. The
time
window can have a length, for example, that is short enough to avoid a torque
spike or to allow for only a negligible torque spike. Additionally, this time
window
may be connected to the output of the transmission. In one embodiment, this
connection expands or contracts the time window, depending on changes to the
output speed. The orientation of drive gears 121a-f can therefore be pre-
determinable within a window of time. As a result, while engagement or
disengagement of a clutch may re-orient drive gears 121a-f for continued
engagement with driven gears 132a-c, it may be unnecessary to even clutch the
disengagement of drive gears 121 a-f and driven gears 132a-c.
While embodiments of the present invention can employ drive gears each of the
34
CA 02736815 2011-04-14
same physical size, and driven gears each of the same physical size, it should
be
appreciated that such relationships are not necessary. Moreover, while drive
gears
and driven gears may, in some embodiments, be of respectively different
physical
sizes, any particular variation in physical size is not a requirement for a
transmission as disclosed herein. In fact, the present invention can be
employed
using drive and driven gears of about the same physical size, as disclosed
herein.
Moreover, in some embodiments, the drive and driven gears are spur gears or
helical gears which are substantially the same diameter from one axial end to
the
other axial end, such that they do not have a taper across their width. In
other
in embodiments, however, drive and driven gears may be bevel gears which taper
from one axial end to the other, or may otherwise narrow or have a non-uniform
size from one axial end to the other. More generally, any gear geometry, size
and/or arrangement of gears effective in implementing one or more aspects of
the
functionality disclosed herein may be employed. Accordingly, the scope of the
invention is not limited to the exemplary embodiments disclosed herein.
Now referring to Figures 3A-C, which schematically disclose aspects of a
transmission 200 that is similar in some regards to transmissions 100 (Figure
1A)
and 100' (Figure 1B), one manner of varying gear ratios while maintaining a
connection between the power source and load, and maintaining a constant or
substantially constant engagement between drive and driven gears, is
described.
In particular, Figures 3A-C illustrate transmission 200 at various gear
ratios.
In the example embodiment illustrated in Figure 3A, transmission 200 includes
three driven gears 232a-c which are each configured to rotate about an axis
passing through a respective center. In addition, transmission 200 includes
two
drive gears 220a-b, or drive gear sets, which engage and rotate driven gears
232a-
c. It should be appreciated that the number of driven gears and drive gears is
exemplary only, and that in other embodiments, more or fewer drive gears
and/or
driven gears may be used. Additionally, in some embodiments, and as disclosed
herein, the three driven gears 232a-c can be linked such that they maintain
identical rotations as each driven gear rotates about its own central axis.
Moreover, while in the illustrated example embodiment, driven gears 232a-c are
CA 02736815 2011-12-22
ring gears and are offset at substantially equal angular intervals of about
one
hundred twenty degrees, and drive gears 220a-b are offset at about one hundred
eighty degrees, it should be appreciated that the disclosed configuration and
arrangement of driven gears 232a-c and drive gears 220a-b is exemplary only.
As disclosed herein, driven gears 232a-c can be configured to rotate either
when
engaged by drive gears 220a-b or when caused to rotate by a linkage system. In
addition to their rotational motion, however, ring gears 232a-c may also
translate
in-and-out. For example, as illustrated in Figures 3A-C, each driven gear 232a-
c
can slide in-and-out along a translation path that is offset some amount from
the
to translation path of one or more of the other driven gears. In the
illustrated example
embodiment, for example, driven gears 232a-c each translate along a respective
translation path 233a-c which extends radially from a respective center of
each of
driven gears 232a-c. In some instances, the angular offset of each of
translation
paths 233a-c may be equal. Accordingly, and by way of example only, for three
driven gears 232a-c, the angular offset of each of translation paths 233a-c is
about
one hundred twenty degrees. In this manner each of the driven gears can
translate
and retain the same angular offset from the other driven gears, regardless of
the
radial positioning of the driven gears.
As shown in Figure 3A, driven gears 232a-c create, in this embodiment, a
generally
triangular portion having curved sides which defines a virtual gear 234 which
is in
constant engagement with at least one of drive gears 220a-b. As will be
appreciated, the size and shape of virtual gear 234 can vary and no particular
arrangement, size or shape of virtual gear 234 is necessary. For example, the
shape of virtual gear 234 can change depending on the number of driven gears
defining virtual gear 234 or, as disclosed herein, the radial position of
driven gears
232a-c.
Within virtual gear 234, drive gears 220a-b are positioned at the distal ends
of
levers 219a-b. In addition, and as discussed above, drive gears 220a-b can be
configured to have an orbital motion. Accordingly, in one example embodiment,
levers 219a-b are representative of the distance between drive gears 220a-b
and
the axis about which drive gears 220a-b orbit. Thus, the intersection of
levers
36
CA 02736815 2011-04-14
21 9a-b, at their respective proximal ends opposite the distal ends at which
drive
gears 220a-b are positioned, defines a center through which the axis about
which
drive gears 220a-b orbit passes. Moreover, in addition or in the alternative
to an
orbital motion, each of drive gears 220a-b may rotate about its own,
respective
central axis passing through its respective center.
The illustrated levers 219a-b may be actual or virtual levers in implementing
a
transmission 200 according to the principles disclosed herein. For example, a
physical lever may be attached between a drive gear at the end of the lever
and to
the center of the intersection between levers 219a-b. Alternatively, the lever
may
1o be virtual. For instance, as disclosed in Figures 1A-B, axial shafts 120a-b
may hold
drive gears 121a-f and orbit the drive gears 121a-f about a central, orbital
axis,
without a physical lever arm maintaining a connection between drive gears 121a-
f
and the axis around which they orbit.
Levers 219a-b, whether actual or virtual, may be controlled and varied such
that
their respective lengths can be varied. For example, relative to drive gears
220a-b,
drive gears 220a-b at the ends of levers 219a-b in Figure 3A may slide
radially
outward, such that length of levers 219a-b changes. As illustrated, for
example,
drive gears 220a-b may slide in a radial direction from the position in Figure
3A to
the positions illustrated in Figures 3B and 3C, or to any position between
those
illustrated in Figures 3A and 3C. It can thus be seen that as radial
translation of
drive gears 220a-b occurs from Figure 3A to Figure 3C, the length of levers
219a-b
increases. Similarly, if drive gears 220a-b translate radially from the
position of
Figure 3C to the position in Figure 3B or Figure 3A, the length of levers 219a-
b
correspondingly decreases.
As drive gears 220a-b orbit around the center of levers 219a-b, they can
engage
the various ring gears 232a-c, thereby causing driven gears 232a-c to rotate.
Moreover, as the length of levers 219a-b increases, the radius of the orbit of
drive
gears 220a-b increases, thereby also increasing the length of the orbital path
of
drive gears 220a-b. For drive gears 220a-b to maintain a constant angular
velocity
while following a longer orbital path, the linear velocity of drive gears 220a-
b is
necessarily increased. Similarly, as the length of levers 219a-b decreases,
and the
37
CA 02736815 2011-12-22
radius and length of the orbital path of drive gears 220a-b decrease, the
linear
velocity of drive gears 220a-b correspondingly decreases.
Accordingly, the linear velocity of any point on drive gears 220a-b is related
to the
length of levers 219a-b and to the angular velocity at which drive gears 220a-
b
rotate. For example, in the example embodiment disclosed in Figures 3A-C,
drive
gears 220a-b mate with driven gears 232a-c at engagement points 235. It will
be
appreciated that at engagement points 235 on drive gears 220a-b, engagement
points 235 have a linear velocity which is related with the orbital motion of
drive
gears 220a-b. In particular, if v1 is the linear velocity of drive gears 220a-
b at
1o engagement points 235, v, is related to the orbital motion of drive gears
220a-b by
the equation: v, = w, = 1, where w, is the angular velocity, i.e. the orbital
speed or
orbital RPMs, of drive gears 220a-b, and I is the distance from the engagement
points 235 to the axis about which drive gears 220a-b orbit. Accordingly, it
can be
seen that v1 is directly proportional to 1, and if w, is held constant, v,
will increase
as I increases, and v1 will decrease as I decreases.
Moreover, if driven gears 232a-c rotate about their centers when engaged by
drive
gears 220a-c, the linear velocity, v2, of the point of engagement on driven
gears
232a-c is related to the rotational motion of driven gears 232a-c by the
equation v2
= w2 - r, where w2 is equal to the angular velocity, i.e. the rotational speed
or
RPMs, of driven gears 232a-c, and r is the radius of driven gears 232a-c.
Thus, it
can be seen that v2 is directly proportional to w2, such that if r is held
constant, as
v2 increases, w2 increases, and as v2 decreases, w2 also decreases.
Additionally, engagement points 235 are common to drive gears 220a-b and
driven
gears 232a-c, such that at engagement points 235, drive gears 220a-b and
driven
gears 232a-c have the same linear velocity. Thus, at engagement points 235, vi
=
v2. Accordingly, in a system in which the angular velocity, w,, of drive gears
220a-
b and radius, r, of driven gears 232a-c are substantially constant, and the
orbital
distance I of drive gears 220a-b, and the angular velocity, w2, of driven
gears 232a-
c, can vary, the relationship between I and w2 can be expressed as I = k = w2,
where k is a constant equal to r / w1. Thus, W2 and I are directly
proportional and
as one increases or decreases, the other will change accordingly. Accordingly,
it
38
CA 02736815 2011-04-14
can be seen as the length of levers 219a-b increase and decrease, thereby
increasing or decreasing the linear velocity of the point of engagement of
drive
gears 220a-b, the angular velocity of driven gears 232a-c correspondingly
increases or decreases.
The relationship between the length of levers 219a-b and the angular velocity
of
driven gears 232a-c can be further illustrated by two simple examples. It will
be
appreciated that the following examples are not limiting of the present
invention
and are, instead, presented merely to illustrate certain aspects of the
present
invention.
1o In a first example, a transmission, such as transmission 200 of Figure 3B,
can be
arranged such that levers are 1 inch in length. In addition, it can also be
assumed
that the transmission can be arranged or constructed such that the diameter of
the
drive gears is equal to 1 inch, the radius of the driven gears is equal to 8
inches,
and that the drive gears can orbit at a constant angular velocity of 2000 RPM.
It
will thus be appreciated that in such an example, the linear velocity of an
engagement point on the outer edge of the drive gears, at the furthest point
from
the axis about which the drive gears orbit, is about equal to 4000
inches/minute (w,
= 2000 RPM and 1= (1 inch + 1 inch)).
Further, inasmuch as the engagement point is shared between the drive gears
and
the driven gears, the linear velocity, v2, of the driven gears at the
engagement point
is equal to the linear velocity, v,, of the drive gears at engagement point.
Accordingly, v2 is, in this example, also equal to 4000 inches/minute.
Moreover,
inasmuch as the driven gears rotate about their central axis and have a fixed
radius, the angular velocity, w2, of the driven gears can be determined and is
about
equal to 500 RPM (v2 = 4000 inches/minute and r = 8 inches). Thus, the angular
velocity, w2, of the driven gears is four times less (500 RPM compared to 2000
RPM) than the angular velocity, w,, of the drive gears, such that this
exemplary
arrangement of the drive gears and the driven gears provides a 4:1 gear
reduction.
In a second example, however, take a transmission such as transmission 200
from
Figure 3C, and assume, as in the first example, that the drive gears have
diameters
39
CA 02736815 2011-04-14
of 1 inch, the radius of the driven gears is constant and equal to 8 inches,
and that
the drive gears orbit at a constant angular velocity of 2000 RPM. In this
example,
however, assume also that the lever length has been increased to, for example,
3
inches. As will be appreciated, if such an increase to the lever length is
made, the
linear velocity, vi, of an engagement point on the outer edge of the drive
gear, at
the furthest distance from the axis about which the drive gears rotate, is
about 8000
inches/minute (wi = 2000 RPM and / _ (1 inch + 3 inches)). As the driven gears
have the engagement points in common with the drive gears, the linear
velocity, v2,
of the driven gears at the engagement points is also about 8000 inches/minute.
io Moreover, as the linear velocity, v2, has increased, the angular velocity,
w2, of the
driven gears must also necessarily increase over the angular velocity of the
driven
gears in the first example. For instance, in this second example, the angular
velocity, w2, of driven gears 232a-c is about 1000 RPM (v2 = 8000
inches/minute
and r = 8 inches). Thus, the angular velocity, w2, of the driven gears is only
two
times less (1000 RPM compared to 2000 RPM) than the angular velocity, w1, of
the
drive gears, such that this exemplary arrangement of the drive gears and the
driven
gears provides a 2:1 gear reduction.
Thus it can be seen that by moving drive gears 220a-b radially so as to
increase or
decrease the length of levers 219a-b, the angular velocity of driven gears 232
a-c
can be correspondingly increased or decreased, even if the angular velocity at
which drive gears 220a-b remains constant. Consequently, the angular velocity
of
driven gears 232a-c can change, even for a constant input angular velocity of
drive
gears 220a-b, thereby providing a gear ratio change in transmission 200.
Moreover, it will be appreciated that drive gears 220a-b are not limited to
the two
positions in the above example. Indeed, in some examples, such as that of
transmission 100 illustrated in Figure 1 A and transmission 100' of Figure 1
B, a set
of drive gears can be changeable between a large number, and possibly an
infinite
number, of positions. Each radial position produces a different lever arm, and
each
gear ratio corresponds to a different lever length. Thus, where drive gears
220a-b
can slide along a range of possible positions, drive gears 220a-b can define
an
infinite number of non-discrete gear ratios. Similarly, even where drive gears
220a-
b maintain engagement at only discrete locations, thereby stepping between
CA 02736815 2011-04-14
positions, drive gears 220a-b can step between a finite number of many
different
discrete gear ratios.
For example, with reference to Figure 1A, drive gear sets 120a-b may slide
radially
inward or outward, while driven gears 132a-b correspondingly slide radially
inward
or outward. As discussed above, at each location along a radial translation
path,
the orbital path of drive gear sets 120a-b is of a different length, thereby
defining a
different gear ratio. In some embodiments, as discussed in greater detail
herein,
drive gear sets 120a-b may be configured to maintain constant engagement with
driven gears 132a-c as drive gear sets 120a-b and driven gears 132a-c
translate
io radially. Inasmuch as drive gear sets 120a-b can thus translate to any
location on
a linear path, an infinite number of non-discrete gear ratios may be possible.
It will be appreciated in view of the disclosure herein that it is not
necessary that an
infinite number of non-discrete gear ratios be defined. Indeed, in one
embodiment,
a large number of discrete gear ratios are defined in such a manner that
shifting
between adjacent gear ratios is imperceptible, or nearly imperceptible, such
that
the transmission approximates an infinitely variable transmission. Consider,
for
example, transmission 100' illustrated in Figure 1 B. As noted above,
transmission
100' can include one or more clutches 123 which allow the rotational and/or
orbital
motions of drive gears 121a-f to be at least temporarily interrupted. Such an
interruption may occur by engaging the clutch, which may also coincide with a
gear
ratio change.
According to one example embodiment, for instance, gear ratio changes in
transmission 100' may be of such a small increment that the change is at least
nearly imperceptible. For example, according to one embodiment, the length of
the
orbital path of each available location may increase or decrease by such a
small
amount that the time needed to engage the clutch, move the drive gears 121a-f
and the driven gears 132a-c is so small, that the change can be made in
fractions
of a second, and even nearly instantaneously. To further decrease the time,
such
controls may be performed automatically, by an electronic control system.
Nothing
disclosed herein prevents, however, clutches 123 and/or movement of drive
gears
121 a-f and driven gears 132a-c from being controlled by a human operator.
41
CA 02736815 2011-12-22
According to one embodiment, various discrete orbital paths are available, and
at
each discrete location the virtual gear is a whole integer virtual gear. In
particular,
that is to say that if the virtual gear is circular, the length of the
circumference of the
virtual gear can be divided into a whole number of gear teeth the size of
those on
diving gears 121 a-f or inside driven gears 132a-c, without any partial teeth.
By way
of example, in an illustrative case where the tooth width is one-quarter inch,
a
virtual gear having a circumference of twelve inches is a whole integer
virtual gear
inasmuch as its circumference is divisible into exactly forty-eight whole
teeth.
Accordingly, for the same tooth width, a virtual gear having a circumference
of
io twelve and a third inches is not a whole integer virtual gear inasmuch as
it is
divisible into forty-nine whole gear teeth plus one third of a fiftieth gear
tooth.
By varying the orbital paths of drive gears 121a-f between discrete paths
which
each have lengths that are fully divisible by the width of the gear teeth of
drive
gears 121 a-f, an additional complexity can be reduced. For example, as noted
is above, if drive gears 122a-f slide to a radial position where the virtual
gear defined
by driven gears 132a-c has a circumference which is not a whole integer
virtual
circle, drive gears 121a-f may not properly align with the gear teeth of
driven gears
132a-c as drive gears 121a-f rotate and orbit. Instead, the partial tooth in
the
virtual gear can cause misalignment which lessens the effectiveness of the
20 transmission.
It will also be apparent to one of ordinary skill in the art that a very large
number of
discrete gear ratios can be provided over even a relatively small
translational
distance. For instance, it will be appreciated that in order to change from
one
whole integer virtual circle to the next whole integer virtual circle, the
circumference
25 needs to only increase or decrease by an amount equal to the tooth width.
Inasmuch as drive gears 121a-f and driven gears 132a-c move radially and the
radius and circumference of the virtual gear are related by the equation c =
2=rr=r, it
can thus be deduced that where tW is equal to the tooth width, a radial change
equal to tW/(2rr) will change the size of the orbital path of drive gears 121
a-f, as well
3o as the virtual gear defined by driven gears 132a-c, to the next whole
integer virtual
gear. Moreover, the transmission may be controlled to ensure that drive gears
42
CA 02736815 2011-04-14
121 a-f engage driven gears 132a-c only at locations where the defined virtual
gear
is a whole integer virtual gear. To control engagement in this manner, a
mechanical or electrical control may be used. For instance, a lock-step
mechanical
shifting mechanism may be utilized. Alternatively, or in addition thereto, an
electronic control system may control the movement, engagement, and
disengagement of drive gears 121 a-f and driven gears 132a-c.
In embodiments in which the mating gear teeth of drive gears 121a-f and driven
gears 132a-c are of a relatively small size, it will be appreciated that the
discrete
gear ratios can be effected with very little radial translation of drive gears
121a-f
1o and driven gears 132a-c. For instance, in an illustrative example, a drive
gear may
have a gear tooth profile in which gear teeth are one-half inch wide.
Consequently,
drive gears 121 a-f and driven gears 132a-c would need to move radially a
distance
of only 1/(4rr) inches, or approximately 0.08 inches, to move between gear
ratios.
Accordingly, by drive gears 121a-f and driven gears 132a-c translating a
radial
distance of only two inches, more than twenty-five discrete gear ratios can be
obtained.
Additionally, inasmuch as the radial distance required to move between gear
ratios
is so small, there is also very little time needed to make the change. As a
result, a
change from one gear ratio to the next can, in some embodiments, occur nearly
instantaneously. For instance, in the example of transmission '100'. of Figure
113,
the time needed to engage clutch .123, radially translate drive gears 121a-f
and
driven gears 132a-c to the next whole integer virtual circle and orbital path,
and
then disengage the clutch to re-start the rotational and/or orbital motions of
drive
gears 121 a-f can be only a fraction of a second. Indeed, where such control
of
transmission 100' is controlled automatically by a control system, the time to
complete the change can be on the order of hundredths or tenths of a second.
While the foregoing discussion discloses a stepped transmission which steps
between discrete gear ratios spaced at one-tooth increments to the size of the
virtual gear, it will be appreciated that this feature is not limiting, and
that other
3o embodiments are contemplated. For example, as noted above, in embodiments
such as transmission 100 (Figure 1A), the transmission may not be stepped at
all,
43
CA 02736815 2011-12-22
but may instead slide between gear ratios. In other embodiments of stepped
gear
changes, however, other increments other than one-tooth may be used. For
instance, in other embodiments steps between gear ratios may be made at two,
three, four, or more gear tooth increments. In still other embodiments, the
steps
between gear ratios may be dependent on the number of drive or driven gears,
or
drive and driven gear positions, in the transmission. For example, a
transmission
having five drive gears, or five drive gear positions, may step between gear
ratios
in five tooth increments. Similarly, a transmission having three driven gears,
or
three driven gear positions, may step between gear ratios in three tooth
io increments.
As noted previously, changes to the gear ratio can be effected while the input
to the
transmission continues rotating, such that the transmission is connected to
the
power source while gear ratio changes are made. It will be appreciated that in
other embodiments, however, a transmission according to the present invention
may be disconnected from the power source, or the power source may be shut
down while a gear ratio change is made. For instance, in one embodiment a
transmission according to the present invention may be implemented in a gear
box
connected to a conveyor. To change between gear ratios, the power to the
conveyor system may be turned off. A user may then radially translate the
drive
and driven gears, whether it be manually, electronically, or in some other
fashion,
to a desired gear ratio, and re-engage the power. In such a case, it will also
be
appreciated that clutches 123 (Figure 113) may also be unnecessary and can be
omitted.
Although some of the foregoing examples make certain assumptions about the
number, size, positioning, angular velocities, and gear teeth of drive gears
220a-b
and driven gears 232a-c, it should be appreciated that these assumptions have
been made for the above examples only and are in no way limiting of the
present
invention. Instead, they are merely identified to more clearly indicate the
manner in
which a transmission according to a particular example embodiment of the
present
invention changes between gear ratios. In fact, it will be appreciated that
one
aspect of a transmission such as transmission 100 (Figure 1A), transmission
100'
44
CA 02736815 2011-04-14
(Figure 1 B) and transmission 600 (Figures 11A-B), is that they are scalable
for use
in a wide variety of applications. Thus, it is contemplated that the drive and
driven
gears can be any of various sizes, have any of various numbers of gears and
gear
teeth with any suitable size, and can operate at any of various angular
velocities,
as necessitated by the application in which the transmission is implemented.
For
example, an example transmission of the present invention may be implemented
in
connection with an aircraft carrier or other large marine craft, and may
employ very
large drive and driven gears which are many feet, if not yards, in diameter.
Alternatively, another example transmission of the present invention may be
io implemented in, for example, a model car, and may employ very small drive
and
driven gears with diameters measured in centimeters, if not millimeters, in
diameter.
As disclosed previously with regard to Figures 3A-C, as levers 219a-b increase
in
length, and the orbital paths of drive gears 220a-b change, driven gears 232a-
c
must also move so as to maintain engagement with drive gears 220a-b. Thus, as
illustrated in Figures 3A-C, as driven gears 232a-c move, for example along a
respective translation path 233a-c, the size of virtual gear 234 changes.
Accordingly, gear ratio changes within transmission 200 can occur even without
causing drive gears 220a-b to engage differently sized sets of physical,
driven
gears. Instead, as disclosed herein, gear ratio changes can be made by
changing
the size of the orbital path of drive gears 220a-b as well as the size of
virtual gear
234 engaged with drive gears 220a-b.
To maintain constant or substantially constant engagement between drive gears
220a-b and driven gears 232a-c over gear ratio changes in which the size of
virtual
gear 234 is changed, the translational movement of driven gears 232a-c along
translation paths 233a-c can be synchronized with changes to the length of
levers
219a-b which correspondingly cause the radial movement of drive gears 220a-b.
In particular, as drive gears 232a-c are moved outward or inward, the length
of
levers 219a-b can be substantially simultaneously increased or decreased a
corresponding amount, thereby allowing driven gears 232a-c and drive gears
220a-
b to remain substantially constantly engaged throughout their respective
orbits and
CA 02736815 2011-04-14
rotations, and, as discussed above, optionally even during an increase or
decrease
in the length and/or diameter of the orbital path of drive gears 220a-b. In
this
manner, substantially constant engagement is maintained at various gear
ratios.
Moreover, even in embodiments in which an exemplary transmission uses stepped
gear ratio changes, such changes may be effected by such small movements in
drive gears 220a-b and driven gears 232a-c that the time during which drive
gears
220a-b are disconnected from a transmission input interface and/or external
power
source can be negligible and imperceptible, or almost imperceptible. In such
an
embodiment, drive gears 220a-b and driven gears 232a-c can effectively provide
io the same desired effects as a transmission which slides between gear
ratios.
Where multiple steps are provided, a stepped transmission as described herein
can
therefore effectively operate in a sliding fashion in which the transmission
maintains
an effective connection between the drive gears 220a-b and driven gears 232a-c
throughout a change in gear ratios.
For instance, at about the same time that driven gears 232a-c slide in or out
on
their respective translation paths 233a-c, thereby varying the size of virtual
gear
234 and the length of the orbital path of drive gears 220a-b, the length of
levers
219a-b can be adjusted. Consequently, even where a transmission according to
the present invention engages a clutch to stop or prevent the rotational
and/or
orbital motion of drive gears 220a-b, when the clutch disengages, the drive
gears
220a-b and driven gears 232a-c are in position to continue engagement at the
new
lever length. As engagement is thus maintained when drive gears 220a-b again
start rotating and orbiting, drive gears 220a-b can drive driven gears 232a-c.
Moreover, as disclosed herein, as the linear velocity of engagement points 235
on
drive gears 220a-b increases or decreases, based at least partially on the
length of
levers 219a-b, the corresponding linear velocity at engagement points 235 on
driven gears 232a-c also increases. As driven gears 232a-c may be of a fixed
size,
and can, in some embodiments, always rotate around axes aligned with the
centers
of driven gears 232a-c, the increased linear velocity creates an increased
angular
velocity of driven gears 232a-c. Thus, gear ratio changes may be made by
varying
the length and/or diameter of orbital path of drive gears 220a-b and/or by
varying
the size of virtual gear 234, and without changing engagement between
differently
46
CA 02736815 2011-12-22
sized physical gears.
As noted herein, a drive gear may be located at the end of each actual or
effective
lever. Such a drive gear may, in some embodiments, act as a moon gear which
has any of a number of aspects. For example, drive gears 220a-b may maintain
substantially constant engagement with a driven gear, such as driven gears
232a-
b, so as to drive the driven gears to obtain various outputs corresponding to
a
variety of gear ratios. In addition, and as disclosed herein, drive gears 220a-
b may
rotate about their respective central axes and further orbit around an
external axis
such as an axis passing through the center of the intersection between levers
io 219a-b. For example, as disclosed herein, drive gears 220a-b may thus
rotate in a
controlled and predetermined manner that ensures that as a drive gear is about
to
enter into engagement with a driven output gear, the gear teeth of the drive
and
driven gears are synchronized. Additionally, drive gears 220a-b can translate
radially. As disclosed above, the radial motion of the moon gear enables the
transmission to move along a range of ratios, in very small, possibly
infinitely small,
increments, in either a sliding or stepped fashion. Accordingly, drive gears
may
translate radially to create a variable output and/or rotate to attain
synchronized
engagement with the corresponding driven gears. Moreover, inasmuch as the
drive gears can translate radially and cause the transmission to slide or step
between gear ratios in substantially non-discrete or in discrete gear ratios,
the
transmission can change gear ratios without producing a torque spike, or by
producing only an insignificant torque spike, which does not damage the
transmission and/or a drive train coupled to the transmission.
Various possible motions of an exemplary drive gear 320a and a driven gear 332
are illustrated in Figure 4. In particular, Figure 4 illustrates two drive
gears 320a-b
which are synchronized with driven gear 332 which may be implemented, for
example, as a ring gear. More or fewer drive and/or driven gears may be used,
however, as necessary or desired for a particular application. Thus, the two
drive
gears 320a-b and one driven gear 332 are depicted merely for illustrative
purposes.
3o As shown in Figure 4, at any given lever length, drive gear 320a can orbit
around
an axis passing through point 320', or around any other axis that is offset
from the
47
CA 02736815 2011-04-14
center 320" of drive gear 320a. Accordingly, drive gear 320a can orbit and
move
along an orbital path 325, for example. In some embodiments, a shaft and/or
carrier (not shown) aligned with point 320' may directly or indirectly cause
drive
gear 320a to orbit in a clockwise direction about an axis passing through
point 320'.
As drive gear 320a orbits, it may also be configured to rotate about its
center 320".
For example, as disclosed previously, a power transfer system may be
implemented which receives a power input and translates a power input into,
for
example, rotational and orbital motions of various drive gears.
The rotation of drive gears 320a can be in a counter-clockwise direction such
that
io the rotation is opposite the orbital direction of drive gear 320a.
Moreover, this
rotation can be implemented to synchronize drive gears 320a-b with driven gear
332 such that as drive gears 320a-b prepare for engagement with driven gear
332,
the teeth of drive gears 320a-b are properly aligned with the teeth of driven
gear
332. As drive gear 320a then enters into engagement with driven gear 332, this
engagement and the rotational and orbital motions of drive gear 320a then
cause
driven gear 332 to rotate about its center 332'.
As can further be seen in Figure 4, drive gears 320a-b may further be
configured to
translate in a radial direction that increases or decreases the length of the
orbital
path the drive gears follow while engaged with the driven gears in the
transmission.
While in the illustrated embodiment, drive gear 320a is illustrated as being
able to
translate inward and outward along a vertical path 331, it should be
appreciated
that such motions are exemplary only. In particular, inasmuch as drive gear
320a
has an orbital motion, it will be appreciated in light of the disclosure
herein that
regardless of its orientation or position along the orbital path, drive gear
320a can
translate radially inward, towards center 320', or radially outward, away from
center
320', along a path that is offset at any angular interval from vertical. In
addition, the
driven gears, such as driven gear 332, may translate radially in a
predetermined
direction. For instance, in the illustrated embodiment, driven gear 332
translates
inward and/or outward, for example, along a translation path :333 that is
offset
about one hundred twenty degrees from the vertical, and which passes through
center 320'. As disclosed herein, when multiple driven gears are used, each
driven
48
CA 02736815 2011-04-14
gear can travel in a predetermined direction along a translation path and, in
some
embodiments, the predetermined directions can each be offset with respect to
each
other in substantially equal angular increments.
It should be appreciated in light of the disclosure herein that the net sum of
the
rotation and orbit of drive gear 320a controls the angular velocity at which
drive
gear 320a is rotated. In particular, and as previously disclosed herein, drive
gears
320a-b can orbit in a first direction, e.g., clockwise, while they rotate
about their
respective centers in a second, opposite direction, e.g., counterclockwise. In
such
an arrangement, the net sum of the clockwise, orbital motion and the counter-
1o clockwise, rotational motion of drive gear 320a about the point of
engagement with
driven gear 332 will determine the velocity of driven gear 320a. In
particular, each
of the rotational and orbital motions of drive gear 320a will contribute to
the linear
velocity at an engagement point of drive gear 320a to driven gear 332 and,
accordingly, also contribute to the linear velocity of driven gear 332 at that
engagement point and the corresponding angular velocity of driven gear 332
which
produces such a linear velocity. Thus, the net sum of the orbital and
rotational
motions of drive gear 320a will also determine the rotational speed of driven
gear
332.
In light of the disclosure herein, it can further be appreciated that for a
particular
rotational speed at the transmission input, and at a particular lever length
and drive
gear size, the rotation of drive gear 320a about its axis may contribute to
the linear
velocity at an engagement point in an amount that is about equal and opposite
to
the contribution of the orbital motion of drive gear 320a to the linear
velocity at the
engagement point. In such an arrangement, the rotation of drive gear 320a may
thus offset the orbital motion of drive gear 320a, thereby providing a
negligible,
possibly zero, net linear velocity. Thus, the net sum of the rotation and
orbit of
drive gear 320 can produce zero output.
Inasmuch as the linear velocity of drive gear 320a at the engagement points
determines the angular velocity at which driven gear 332 rotates-and thus the
output of the transmission-a zero net linear velocity at the engagement points
will
result in the driven gear having no material rotation. In particular, the
rotation of
49
CA 02736815 2011-04-14
drive gears 320a and the counter orbit of drive gears 320a can neutralize each
other. As a result, drive gear 320a can be engaged with driven gear 332, and
can
maintain its orbital and rotational motion, but will not provide any output to
driven
gear 332, even without the continuous application of clutches or bands to stop
the
motion of driven gear 332. Consequently, the transmission will be in neutral.
Thus, at least some embodiments of a transmission according to the present
invention can provide an engaged neutral in which the rotating and orbiting
drive
gears are engaged with the driven gears, such that the drive and driven gears
are
each connected to the power source, while no output is provided. Moreover, in
io some embodiments, each gear in the system maintains engagement during the
engaged neutral while zero output is provided by the transmission. Thus,
unlike
some automatic transmissions, the drive and driven gears of the present
invention
maintain engagement during a gear ratio change and while in neutral, without
necessitating use of devices which apply an external force to restrict the
gears from
moving.
To remove the transmission from the engaged neutral state, the gear ratio can
be
changed. For example, the gear ratio can be decreased by increasing the lever
length, thereby also increasing the linear velocity associated with an orbit
of the
drive gear over the linear velocity associated with a rotation of a given
drive gear or
gears, and which may be constant, thereby shifting the transmission into a
forward
gear ratio where it can then change between a large, and possibly infinite,
number
of forward gear ratios, including, potentially, an overdrive ratio in which
the output
speed is faster than the input speed. Conversely, if the lever is decreased
such
that the orbital velocity is less than the rotational velocity, the
transmission moves
into a reverse gear ratio, and may change between any number of reverse gear
ratios.
Now referring to Figures 5 and 6, a description of exemplary mechanisms for
moving input drive gears and output driven gears are disclosed. In particular,
Figure 5 illustrates an exemplary mechanism for moving drive gears 121a-f
radially
while they maintain engagement with one or more driven gears. Figure 6
illustrates
an exemplary embodiment of a mechanism for moving driven gears 132a-c in
CA 02736815 2011-04-14
predetermined directions such that they can maintain engagement with the one
or
more drive gears.
In Figure 5, a carrier 111 is illustrated which includes a carrier arm 112
connected
to a transmission input interface 105 and to two ratio reference gears 114. As
disclosed with respect to Figure 1A, as transmission input interface 105
rotates,
carrier arm 112 can also rotate. Moreover, the rotation of carrier arm 112 may
further cause ratio reference gears 114 to rotate around a reference gear 116
which, in turn, can cause one or more sets of drive gears to rotate and/or
have an
orbital motion.
io In some embodiments, carrier 111 is configured to facilitate movement of
drive
gears 121a-f (Figures 1A-B) in a radial direction. As illustrated in Figure 5,
for
example, carrier 111 may include transfer gears 118d which are connected to
drive
rods 124a-b which rotate drive gear sets 120a-b (Figure 1A). Transfer gear
118d
mates with transfer gear 118c, which may be movable along a transfer shaft
122.
As transfer gears 118c and transfer 118d collectively move along transfer
shaft
122, it can be seen that the distance between drive rods 124a-b and the center
of
transmission input interface 105 can increase or decrease. In embodiments in
which the drive gears orbit around an axis aligned with the center of
transmission
input interface 105, for example, as drive rods 124a-b and transfer gears 118c-
d
move outward along transfer shaft 122, and get closer to transfer gears 118a-
b, the
length and diameter of the orbital path traveled by drive rods 124a-b, and the
corresponding orbital path of the drive gears attached to drive rods 124a-b,
increases. Additionally, transfer gears 118c can, in some example embodiments,
move to any position along each half of transfer shaft 122, thereby allowing
the
length of the orbital path traveled by drive rods 124a-b to be varied in very
small,
and possibly infinitely small, increments. Accordingly, transfer gears 118c
can
move along transfer shaft 122 to effect gear ratio changes in transmission
which
slides or steps between gear ratios.
To cause movement of drive rods 124a-b and the attached drive gears, and
thereby change the lever distance of the drive gears, carrier 111 may include,
in
some embodiments, a pinion 125 which is engaged with gear racks 126a-b. Pinion
51
CA 02736815 2011-04-14
125 may be axially fixed with respect to carrier arm 112, while gear racks
126a-b
may be configured to move with respect to carrier arm 112. For example, as
pinion
125 rotates about its center, the teeth on pinion 125 can engage the teeth on
gear
racks 126a-b, thereby causing gear racks 126a-b to move, in this embodiment,
s axially with respect to gear racks 126a-b and radially with respect to the
center of
pinion 125. In particular, as pinion gear 125 rotates in a first direction,
each of gear
racks 126a-b may move radially outward with respect to the center of pinion
125,
while rotating pinion 125 in a second, opposite direction may cause gear racks
126a-b to each move radially inward with respect to pinion 125.
io Gear racks 126a-b may also be coupled to transfer gears 11 8c-d such that
as gear
racks 126a-b move, transfer gears 118c-d move a corresponding distance and/or
in
a corresponding direction. For example, in the illustrated embodiment,
transfer
gears 118c-d are each connected to brackets 127, while brackets 127 are each
connected to one of gear racks 126a-b. In this manner, as gear racks 126a-b
15 move, gear racks 126a-b cause brackets 127 and transfer gears 118c-d to
move
correspondingly. In some embodiments, drive rods 124a-b can be directly
connected to brackets 127. For example, drive rods 124a-b may be directly
connected to brackets 127 such that as pinion gear 125 moves racks 126a-b in
one
direction, rack 126a causes drive rod 124a to move outward or inward with
respect
20 to the center of pinion 125 in a corresponding direction, and rack 126b
causes drive
rod 124b to move outward or inward in a direction corresponding to the
direction of
movement of rack 126b, thereby allowing any drive gears on drive rods 124a-b
to
move radially inward or outward with respect to the centers of drive rods 124a-
b so
as to maintain synchronization with output driven gears that are moving
radially a
25 corresponding distance. Accordingly, carrier 111, including pinion 125,
gear racks
126a-b, brackets 127, transfer gears 118c-d and transfer shaft 1:22, is an
example
of a structural implementation of means for synchronizing movement of the
drive
and driven gears such that substantially constant engagement is maintained
between drive and driven gears over a range of gear ratios.
30 While, in the illustrated embodiment drive rods 124a-b are connected to
brackets
127 and racks 126a-b, it should be appreciated that in other embodiments,
drive
52
CA 02736815 2011-12-22
rods 124a-b may not be directly connected to brackets 127 or racks 126a-b. For
example, drive rods 124a-b may be connected directly to transfer gears 118d
such
that as transfer gears 118d move inward or outward, drive rods 124a-b move in
a
corresponding outward or inward direction. Thus, in embodiments in which
collinear drive gears are mounted on drive rods 124a-b, such as in the manner
illustrated in the examples of Figures 1A-B, the outward or inward movement of
drive rods 124a-b thus causes the drive gears to move radially with respect to
the
axis about which drive gears orbit, such that the orbital path of the drive
gears is
correspondingly increased or decreased.
1o As noted previously, pinion 125 can cause gear racks 126a-b to move as
pinion
125 rotates. Rotation can be supplied to pinion 125 in any of a variety of
manners.
For example, in the illustrated embodiment, a shaft 128 is connected to pinion
125
so as to rotate pinion 125. In some embodiments, shaft 128 extends through
transmission input interface 105 although any other suitable manner of
controlling
the rotation of pinion 125 or causing the radial movement of drive gears 121a-
f
(Figures 1A-B) may be employed.
Figure 6 illustrates an exemplary mechanism for moving a driven gear in
accordance with some embodiments of the present invention. In the illustrated
embodiment, a mechanism for moving a driven gear 132a, such as a ring gear,
for
example, in a predetermined direction is illustrated. The illustration of a
single
driven gear 132a is presented for clarity as it will be appreciated that
similar
devices and mechanisms can be employed for causing the movement of other
driven gears in other predetermined directions as may be desired.
As shown in Figure 6, a driven gear 132a within a transmission may engage a
linkage system 136 that includes an output moon gear 138 connected to an
output
sun gear 140. To enable rotation of driven gear 132a, driven gear 132a can
include an internal gear profile which is selectively engaged by one or more
drive
gears. In addition, and as disclosed herein, driven gear 132a may include a
gear
profile on its outer surface which is configured to mate with the gear profile
of
output moon gear 138. Output moon gear 138 may further be connected to an
output sun gear 140 which is connected to a linkage shaft 142 for linking the
53
CA 02736815 2011-12-22
rotation of driven gear 132a with other driven gears and/or with a
transmission
output interface.
In some embodiments, output sun gear 140 can be fixed at its center, such that
while it rotates, it does not translate in a radial direction. In addition, in
some
embodiments, output moon gear 138 can be configured to at least partially
orbit
around output sun gear 140. In the illustrated embodiment, for example, a
linkage
147 is connected to each of output moon gear 138 and output sun gear 140, such
that if output moon gear 138 is rotated around output sun gear 140, it
maintains a
fixed distance from output sun gear 140, thereby maintaining substantially
constant
io engagement between output moon gear 138 and output sun gear 140.
As will be appreciated in light of the teachings herein, if output moon gear
138 is
rotated around output sun gear 140, driven gear 132a can also move to maintain
its
engagement with output moon gear 138. In some embodiments, as linkage 147 is
rotated, thereby causing output moon gear 138 to roll around output sun gear
140,
the teeth of output moon gear 138 engage the teeth of driven gear 132a and
thereby push or pull against driven gear 132a to thereby move driven gear
132a.
In other embodiments, driven gear 132a may be at least partially enclosed
within a
casing which is connected to linkage 147. In this example, as linkage 147 is
rotated, it causes the casing around driven gear 132a to push or pull the
casing
and driven gear 132a along gear track 143. In yet another alternative, one or
more
grooves may be formed around the circumference of driven gear 132a and linkage
147 is connected to the groove such that as linkage 147 rotates, linkage 147
engages the groove and thereby pushes or pulls driven gear 132a in a
predetermined path to maintain engagement with a drive gear. As will be
appreciated in view of the disclosure herein, such engagement may be
maintained
during changes in gear ratio or only at discrete gear ratios.
In some embodiments, driven gear 132a is further enclosed within a gear track
143
which defines a line of motion, in a predetermined direction, along which
driven
gear 132a can move. Thus, as linkage 147 causes driven gear 132a to move, gear
track 143 defines that translation path. In some embodiments, such as the
example disclosed in Figure 6, gear track 143 defines a substantially linear
54
CA 02736815 2011-04-14
translation path along which driven gear 132a moves. In other embodiments,
however, gear track 143 may define a curved or other type of path along which
driven gear 132a moves. As will be appreciated in light of the disclosure
herein,
gear track 143, in some embodiments restrains the movement of driven gear 132a
such that while driven gear 132a moves radially, driven gear 132a does not
substantially move axially. Thus, driven gears 132a-c can move along a gear
track
such as gear track 143 without substantially moving axially along drive rods
124a, b
(Figures 1A-B). Moreover, it will be appreciated in light of the disclosure
herein that
in embodiments in which driven gears 132a-c move radially but not axially,
drive
io gears 121a-f may also be configured to move radially but not axially so as
to
maintain substantially constant engagement with driven gears 132a-c.
As further disclosed herein, the transmission may include a support 148
defining a
curved path 149. In some example embodiments, curved path 149 is a half-circle
or other portion of a circular path having a radius about equal to the
combined radii
of output moon gear 138 and output sun gear 140, although other curved or non-
curved paths are contemplated. Where output moon gear 138 orbits around output
sun gear 140, curved path 149 may generally correspond to the partial orbital
path
followed by output moon gear 138. In some embodiments, a shaft (not shown)
extends through curved path 149 in support 148, and through the center of
output
moon gear 138 where the shaft connects with linkage 147. In this manner, the
shaft can be moved along curved path 149 to thereby move linkage 147 and cause
driven gear 1 32a to move along the path defined by gear track '143. Linkage
147
may, however, also be moved in other manners. For example, in some
embodiments, a corresponding linkage 147 is formed on the opposing side of
output moon gear 138 and connected to a rotating shaft that is aligned
coaxially
with the center of output sun gear 140. As the rotating shaft rotates, it can
thereby
cause linkage 147 to rotate and cause output moon gear 138 to orbit along a
path
such as curved path 149.
As disclosed herein, the movement of input drive gears and output driven gears
in
a transmission according to at least some example embodiments of the present
invention can be synchronized so as to maintain substantially constant
CA 02736815 2011-12-22
engagement between input drive gears, which can move in any radial direction,
and output driven gears which also move radially along one or more
predetermined
paths. Any number of synchronization systems can be used. For example, in one
embodiment, shaft 128 (Figure 5) which rotates pinion gear 125 (Figure 5), and
a
shaft rotating linkage 147 may be separately controlled. For example, a
transmission according to the present invention may employ, in one example
embodiment, an electromechanical control device, such as a servo motor, to
control each rotating shaft individually. In embodiments in which a
transmission
includes multiple driven gears which translate radially, it can be appreciated
in light
io of the teachings herein that each driven gear may have a separate linkage
and/or
gear track for controlling the radial movement of the various driven gears. In
such
cases, each driven gear may also be controlled separately or as an integral
unit.
In yet another example embodiment, pinion 125 and linkage 147 can be
mechanically synchronized. For example, as disclosed herein, each of pinion
125
and linkage 147 may be partially rotated in both a clockwise and
counterclockwise
direction so as to cause corresponding radial movements of drive gears and
driven
gears, respectively. As a rotating shaft may control each of pinion and
linkage 147,
appropriate gearing may be used to relate the rotation of pinion gear 125 with
the
rotation of linkage 147, thereby obtaining a synchronized radial movement of
the
drive gears and the driven gears.
As should also be appreciated in light of the disclosure herein, the operation
of the
transmission, such as by the radial movement of driven gears 132a-c and moon
drive gears 121 a-f for example, can be performed manually, by using an
automatic
control system, or a combination of manual and automatic control systems to
preserve engagement only at desired gear ratios, and/or optionally to preserve
engagement between drive and driven gears through a gear ratio change. For
example, a shift lever or other mechanism can be mechanically connected to
both
pinion 125 and linkages 147, such as in the manner described above, so as to
allow an operator to manually adjust the gear ratio. In other embodiments,
3o however, an automatic control system, which may be electronic, is used to
control
a mechanism connected to pinion 125 and linkages 147, or which controls pinion
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CA 02736815 2011-12-22
125 and linkages 147 separately.
An automatic control system may be programmed to help implement the efficient
use of the power supply and power input into transmission 100 or 100'. For
example, an automatic control system can include an artificial intelligence
system
which substantially maintains a desired torque or range of torques during a
gear
ratio change and which runs a connected engine at a desired, possibly optimum,
efficiency. For example, as a vehicle begins to move uphill and a lower gear
ratio
is desirable, the artificial intelligence system can identify to the automatic
control
system the position to which drive gears 121a-f and driven gears 132a-c should
be
io radially moved to improve or maximize torque, angular velocity, or
efficiency. In
such an embodiment, for example, the automatic control system may then
transmit
instructions that rotate pinion 125 to change the lever length associated with
moon
drive gears 121a-f while, at the same time or at about the same time, moving
linkages 147 to thereby move driven gears 132a-c along their respective tracks
143
in a manner that causes driven gears 132a-c to be in engagement with moon
gears
121a-f at the location providing the desired gear ratio. As noted previously,
as a
transmission according to the present invention can change between gear ratio
changes with very small, and possibly infinitely small, movements between
drive
and driven gears, any time required to shift from one gear ratio to the next
can be
negligible, such that it appears that the transmission maintains constant
engagement through a gear ratio change.
It should be appreciated in light of the disclosure herein that a variety of
automatic
control systems may thus be designed and suitable for use with embodiments of
the present invention. For example, in Figure 7, one example embodiment of a
suitable electronic control system 180 is schematically illustrated and
includes one
or more input interfaces 162a-c which receive inputs 165a-c from monitoring
devices 172, 182 and 192, which are, for example, sensors, and concerning
parameters associated with a transmission 180, a power source 171, and/or a
load
190. For instance, one or more transmission monitoring devices 182 can be
connected to transmission 180 to determine and send to input interface 162a
information such as the current position of the drive and/or driven gears, the
torque
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CA 02736815 2011-12-22
and/or angular velocity of power input into transmission 180, the torque
and/or
angular velocity of power output from transmission 180, or any other desired
information concerning parameters associated with transmission 180. Similarly,
one or more load monitoring devices 192 can be connected to load 190 to
determine and send to input interface 162c the load and/or any other
information
concerning load parameters.
Additionally, a power source monitoring device 172 may be connected to power
source 171 to obtain engine RPMs or any other information concerning power
source parameters such as, but not limited to, an engine manifold pressure.
For
io example, power source monitoring device 172 may, in one example embodiment,
be connected to an engine manifold and/or other portions of the power source
to
determine the manifold pressure or other such parameters. In general, the
manifold pressure measurement is indicative of the load placed on an engine.
Accordingly, gear ratio changes can be made to reduce the load on the engine
and,
1s thus, change the manifold pressure.
In general, the manufacturer of an engine manifold can specify maximum and/or
minimum manifold pressures at which the manifold should be operated. Thus,
using inputs 165a-c, which transmit information from monitoring devices 172,
182
and/or 192 to automatic control system 160, automatic control system 160 can
20 determine, based on the supplied information, what changes need to be made
to
maintain the manifold pressure within the necessary tolerances.
In other embodiments, however, changes are made within transmission 180 to
adjust the gear ratio without approaching or exceeding the maximum or minimum
manifold pressure. For example, for any particular RPM output by power source
25 171, the operating engine or other power source may operate at optimum
efficiency
only at a particular load or within a narrow range of loads. Accordingly, an
automatic control system 160 according to the present invention can use inputs
165a-c to determine the current operating parameters of transmission 180, load
190 and/or power source 171, and, in some example embodiments, include an
3o artificial intelligence system 164 and/or processor 166 to determine what
changes
can be made to the parameters of transmission 180, power source 171, and/or
load
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CA 02736815 2011-04-14
190 to maintain power source 171 operating at a desired efficiency. For
example,
when automatic control system 160 is provided with the current engine RPMs and
manifold pressure by input 165b, if the manifold pressure is not within a
range of
efficient pressures determined by the artificial intelligence system,
automatic
control system 160 can send electronic signals through one or more outputs
168a-c
to cause changes which will adjust the manifold pressure, RPMs, torque or
other
parameters.
For example, through interfaces 162a-c, automatic control system 160 can send
control output signals along control lines 168a-c that carry control output
signals to
1o power source 171, transmission 180, and/or load 190 which are then
interpreted by
control interfaces 174, 184, and 194 and used to change operating parameters
within one or more of power source 171, transmission 180, and/or load 190 to
effect a desired change. For example, in one example embodiment, automatic
control system 160 may transmit an output 168a to transmission control
interface
184 instructing transmission control interface 184 to change the radial
position of
drive and/or driven gears within transmission 180. Transmission control
interface
184 may thus include electrical, mechanical, or electromechanical control
devices,
or a combination of electrical, mechanical and/or electromechanical control
devices, which then cause the desired change. For example, in one embodiment,
transmission control interface 184 includes servo motors which rotate one or
more
shafts which in turn adjust the radial position of one or more drive gears
and/or one
or more driven gears in transmission 180. Adjusting the radial) positions in
this
manner may, for example, change the manifold pressure within power source 171
to be within a desired, possibly optimum, range.
While manifold pressure is indicative of the load placed on the power source,
in
some embodiments, an input such as input 165 may be connected directly to a
load measurement device 192 and to automatic control system 160, such that
automatic control system 160 can receive information about the load directly,
rather
than inferentially through the manifold pressure. For example, in an elevator
system, an electric motor may move the elevator such that an input into the
automatic control system may comprise the load, in pounds for example, of the
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CA 02736815 2011-04-14
elevator carriage and passengers. In such an embodiment, the automatic control
system may also determine at what speed the transmission output should be in
order to have optimum output efficiency for a given input power. In this
example,
the automatic control system may, for example through artificial intelligence
system
164, include or have access to memory or another storage mediurn which
contains
a table, algorithm, or other information which allows automatic control system
160
to identify the gear ratio or positioning of drive and driven gears which
achieves an
efficient use of the engine. A processor 166 within the automatic control
system
may, accordingly, access artificial intelligence system 164, and may,
accordingly,
1o retrieve and process the information in the memory or storage within
automatic
control system 160, to thereby retrieve the desired positioning or the changes
necessary to the positioning of the drive gears and driven gears. An
electronic
control signal can then be sent, as output 168a, for example, to be received
in
transmission control interface 184 which then effects such a change within
transmission 180 to obtain a different gear ratio and/or output speed.
While the disclosure herein concerns an automatic control system and refers in
part
to maximizing efficiency of the power source, it should be appreciated that
the
automatic control system may operate in other manners. For example, in some
embodiments, the automatic control system is programmed to maximize or
minimize power and/or torque output. In still other embodiments, the automatic
control system is further programmed to control the power source to obtain
various
output speeds. In yet other embodiments, the automatic control system is
selectably changeable between various modes of operation. For example, an
operator may choose whether to maximize efficiency or power while the control
system is programmed to operate in either manner.
In addition, while the example embodiment disclosed in Figure 7 illustrates a
centralized automatic control system 160 which monitors and/or controls one or
more of power source 171, transmission 180, and load 190, it should be
appreciated that this is exemplary only and not limiting of the present
invention.
3o For example, in some embodiments monitoring devices 172, 182, 192 and/or
control interfaces 174, 184, 194 contain circuitry or programming which allows
CA 02736815 2011-04-14
them to act independent of a centralized control system. In one example
embodiment, for instance, a feedback loop 191 connects power source 171,
transmission 180, and/or load 190 to thereby allow monitoring devices 172,
182,
192 or control interfaces 174, 184, 194 to obtain information from, and/or
control,
the other elements of the system. For example, transmission control interface
184
may, in one example embodiment, receive through feedback loop 191 an
indication
of the manifold pressure in power source 171 from monitoring device 172 or of
the
load from load monitoring device 192. Using dedicated or programmed logic,
transmission control interface 184 may then generate control signals or
otherwise
io control transmission 180 so as to modify the gear ratio of transmission 180
in order
to, for example, maximize the efficiency, power, torque, or other parameters
of
power source 171.
By using control signals or otherwise controlling the motion and parameters of
transmission 180, the drive and driven gears can be synchronized. For example,
as the motion of the drive and driven gears is synchronized to allow
engagement
between the drive and driven gears along at a large, possibly infinite, number
of
different orbital paths of the drive gears, the teeth of the drive gears
should also be
synchronized with the teeth of the driven gears to maintain engagement for
efficiently driving the drive gears, and to ensure that when engagement is to
occur,
a tooth of the drive gear properly mates in or near the root of a driven gear
tooth.
Now referring to Figure 8, a description of one exemplary manner in which the
gear
teeth of drive gears can be synchronized with the gear teeth of driven output
gears
is described.
As disclosed in Figure 8, for example, a transmission may include a reference
gear
416. Reference gear 416 may, but need not necessarily, correspond to reference
gear 116 illustrated in Figure 1A. In some embodiments, reference gear 416 is
fixed such that it does not translate or rotate, and thus provides a
stationary
reference point for synchronizing drive and driven gears. In other
embodiments,
however, reference gear 416 may be movable to synchronize drive and driven
gears.
Reference gear 416 may be used to synchronize the engagement of teeth of moon
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CA 02736815 2011-04-14
drive gears with the teeth of driven ring or spur gears. As illustrated, for
example,
imaginary reference degree lines 445 can extend an infinite length i from each
tooth
of reference gear 416. Degree lines 445 are, accordingly, spaced at
substantially
equal angular intervals and represent the number of degrees by which the teeth
of
reference gear 416 are separated. Accordingly, even if the arc distance
between
degree lines 445 are increased, such as when the lever increases and drive
gears
420 moves radially outward, the degrees of radial separation remain constant.
A corresponding drive gear 420 is coupled, in this embodiment, in a one-to-one
ratio with reference gear 416. As a result, the rotation and orbit of drive
gear 420
io are controlled such that when drive gear 420 orbits around reference gear
416, the
gear teeth of drive gear 420 are always in alignment with the gear teeth of
reference gear 416. For example, as shown in Figure 8, when drive gear 420 is
centered on a reference degree line 445, a tooth of drive gear 420 is directly
aligned with the reference degree line 445. Moreover, as drive gear 420
rotates
and orbits to the position of drive gear 420', it can be seen that the orbit
and
rotation have been controlled such that the tooth of drive gear 420' is also
aligned
with a degree line 445.
Further, controlling the rotation of drive gear 420 in this manner can result
in
alignment of drive gear 420 with reference gear 416, regardless of radial
position of
drive gear 420. In particular, drive gear 420 may translate in-and-out in a
radial
direction. However, no matter what the radial distance between reference gear
416
and drive gear 420, a gear tooth of drive gear 420 remains in alignment with a
corresponding tooth of reference gear 416 along degree line 445. Consequently,
reference gear 416 is used to provide synchronization of gear teeth according
to
degrees of rotation rather than by arc distance and is, accordingly, an
example
structural implementation of means for synchronizing the drive and driven
gears
such that substantially constant engagement is maintained between one or more
drive and driven gears over a range of gear ratios. Additional examples of
means
for synchronizing the drive and driven gears are elsewhere disclosed herein,
such
3o as, for example, with respect to Figures 1A-B, 6 and 11A-B.
Although Figure 8 discloses drive gear 420 and reference gear 416 each having
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CA 02736815 2011-04-14
the same number of teeth, such that the teeth are in a one-to-one
relationship, it
should be appreciated that this arrangement is not necessary,, and that other
relationships may be used. For example, in some other embodiments, a reference
gear has a different number of gear teeth as compared to the drive gear. In
such
embodiments, the reference gear and drive gears may, for example, have numbers
of teeth that are related by a common divisor. For instance, the common
divisor
may be the number of driven gears or driven gear positions within the system.
In
one exemplary embodiment, a reference gear, such as reference gear 116 (Figure
1A), for example, has ninety teeth and a drive gear has six gear teeth. In
such a
io case, it can be seen that the number of teeth of each gear is divisible by
three and
six. In embodiments in which the number of driven gears is the divisor for the
gear
teeth, such an embodiment may, accordingly, have three or six driven gears.
In some embodiments, such as that disclosed in Figures 1A-B, for example, the
numbers of teeth on a ratio reference gear 114 and/or on a driven gear can
also be
related by the same or a different common factor. For instance, ratio
reference
gears 114 may have thirty teeth and driven gears 132a-c may have thirty-six
teeth
on the internal gear profile, such that the numbers of teeth on ratio
reference gears
114 and driven gears 132a-c are also divisible by three and six. It should be
appreciated that the arrangements and numbers of teeth disclosed herein are
exemplary only and that other numbers of teeth and/or common divisors may be
used. For example, in some embodiments, reference gear 116, ratio reference
gear 114, drive gears 121a-f, and driven gears 132a-c may have different
numbers
of teeth that are divisible by three, six, or some other common divisor. For
example, in one embodiment, a reference gear and ratio reference gear can each
have ninety-six teeth, while each drive gear has eighteen teeth, and each
driven
gear has seventy-two teeth. Thus, it can be seen that the number of teeth on
the
reference gear, ratio reference gears, drive gears, and driven gears is each
divisible by three and six. Moreover, in example embodiments in which there
are
three or six driven gears, the number of teeth on the reference gear, ratio
reference
gears, drive gears, and driven gears is each also divisible by the number of
driven
gears.
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CA 02736815 2011-12-22
In still other embodiments, the numbers of teeth of the various gears are
divisible
by other divisors such as, for example, two, four, five, seven, eight, and so
on
which may or may not be the same as the number of driven gears or driven gear
positions. In still other embodiments, the number of teeth may be divisible
only by
a common divisor of one, and the teeth can be maintained in synchronization by
constant engagement between the drive and driven gears. For example, in one
example embodiment, a reference gear can have sixty teeth, a reference gear
fifteen teeth, a drive gear twenty teeth, and a driven gear sixteen teeth.
Accordingly, it can be seen that the only divisor common to each gear is one.
io In addition, as further illustrated in Figures 1A-B, drive gears 121a-f may
be
connected to reference gear 116 by elements that include ratio reference gears
114 which can have thirty teeth, or some other number of teeth that are also
divisible by the same or a different divisor. As noted previously, ratio
reference
gears 114 can engage and rotate around reference gear 116, and thereby impart
to
drive gears 121a-f a rotational and/or orbital motion. In particular, due to
their
connection with reference gear 116, by way of ratio reference gears 114, drive
gears 121a-f each rotate around their respective central axes and orbit as a
group
around an external axis which is, in the illustrated embodiment, aligned with
the
center of reference gear 116. In this manner, the combination of ratio
reference
gears 114 and reference gear 116 causes drive gears 121 a-f to rotate a
predictable
angular amount, regardless of the radial position and lever length associated
with
drive gears 121 a-f, such that a gear tooth of a drive gear 121a-f can always
be
aligned with a gear tooth of a driven gear 132a-c when they enter into
engagement.
Accordingly, ratio reference gears 114 and reference gear 116 are,
collectively and
individually, examples of structural implementations of means for
synchronizing
one or more drive and driven gears such that substantially constant engagement
is
maintained between one or more drive and one or more driven gears over a range
of gear ratios. Moreover, inasmuch as carrier 111 (Figure 5) can be configured
to
move drive rods 124a-b radially, thereby causing drive gears 121a-f to move
3o radially inward or outward and maintain engagement with output gears 132a-
c,
which also move radially inward and outward, thereby changing the ratio
between
transmission input interface 105 and transmission output interface 170,
carrier 111
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CA 02736815 2011-04-14
is also an example of a structural implementation of means for synchronizing
drive
and driven gears such that substantially constant engagement is maintained
between one or more drive and driven gears during gear ratio changes and over
a
range of gear ratios.
To maintain constant synchronization between the teeth of drive and driven
gears,
the drive gears and driven output gears may have involute gear teeth of
substantially the same diametrical pitch. As a result of this configuration,
the teeth
of the drive gears properly mate with the teeth of the driven gears when in
dead
center engagement as well as in any other phase of engagement, and provide a
to constant output to the drive gears regardless of the phase of engagement.
As well,
the teeth of the drive and driven gears also wear less rapidly than gear teeth
which
do not align in all phases of engagement. Moreover, as disclosed previously,
the
drive gears and the reference gear can have an equal number of teeth, or any
other compatible number of teeth such that when a drive gear is aligned on a
degree reference line of the reference gear, a tooth of the drive gear is also
centered on the line of the reference gear at top dead center. In some
embodiments, for example, the numbers of teeth on the reference gear, ratio
reference gears, drive gear and/or driven gears may be divisible by a number
that
is greater or less than the number of driven gears. In other embodiments, the
divisor may be equal to the number of driven gears, although this feature is
not
limiting of the present invention.
The use of the number of drive gears as the common divisor may be useful for a
variety of reasons. For example, this approach can be used to ensure that the
center of each drive gear falls upon a reference line. Moreover, as noted
previously, the number of teeth of the drive gear may be divisible by the same
divisor. This approach can also be useful in that when a tooth of one drive
gear
engages a driven gear at top dead center, all of the driven gears will have
grooves
that are lined up, at top dead center, with the radial degree lines of the
reference
gear. In some embodiments, the combination of these ratios and features link
the
3o rotation of the drive gear teeth with the rotation and position of the
teeth and
grooves on the driven gear such that regardless of the lever length and radial
CA 02736815 2011-04-14
position of the drive and driven gears, the gear teeth of the drive and driven
gears
will be synchronized as the drive and driven gears come into and out of
engagement. Accordingly, the drive gears may translate radially outward to
create
a variable output in small increments and/or rotate to synchronize engagement
with
the driven gears.
As noted above, if the teeth of all of the drive gears become disengaged from
all of
the teeth of the driven gears, such that there is no engagement between input
drive
gears and output driven gears, or if the driven gears are otherwise not
connected to
the transmission input interface, the load driven by the transmission is
effectively
io disconnected from the power source and the load coasts until the
transmission
reengages the drive and driven gears and/or the driven gears with the
transmission
input interface. In environments and applications in which it is desirable to
maintain
a constant connection to the power source, and thereby preserve a constant
flow of
power from the engine to the load, it is desirable therefore to ensure that
there is
constant engagement, or at least substantially constant engagement which
provides essentially the same desirable results as constant engagement,
between
the teeth of the drive gears and driven gears that determine the gear ratio of
the
transmission. As described previously, this can be accomplished by, for
example,
moving the drive gears in an orbital path around an external axis that is
centered
on a reference gear. As engagement is maintained, the driven gears
collectively
rotate about their respective centers and provide power output. In addition,
when
the driven output gears are offset from the orbital axis of the drive gears,
the drive
gears can alternately engage the output gears such that a disengaged drive
gear
will always be preparing to line up for synchronous engagement as it
approaches
and intersects a line of the reference gear. Additionally, substantially
constant
engagement which provides the desirable results of constant engagement can
also
be maintained by providing many gear ratios such that very short translational
movements, which can each be performed in very little time, can change gear
ratios.
While the example disclosed embodiments generally relate to embodiments of a
transmission in which two sets of drive gears engage, and drive, three driven
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CA 02736815 2011-04-14
gears, it should be appreciated that this arrangement is illustrative only and
not
limiting of the present invention, and that a variety of other arrangements
having
different numbers of drive gears, drive gear sets, and driven gears can be
used.
Moreover, it is not necessary that the drive gears be moon or spur gears or
that the
driven gears be ring gears. In fact, because the transmission components
operate
synchronously, whether in a reverse, forward or neutral mode, the power can
also
flow through the transmission in reverse. For example, the torque flow path
can be
reversed through the transmission to create a different torque flow path that
is
desirable for some applications. For example, the reverse torque flow path of
1o some embodiments may allow the transmission to operate at higher speeds
with
less torque.
Moreover, a reversed torque flow path may allow the ring gears to operate as
drive
gears and the moon or spur gears to act as driven gears. In such an
embodiment,
it will also be appreciated that the driven gears thus can have orbital and
rotational
movements while the drive gears then translate radially in-and-out along
predetermined paths which are offset from each other at angular intervals. In
an
example embodiment in which the power flow is reversed, however, the reverse
power flow may eliminate the engaged neutral feature of the transmission
and/or
the easy transition between forward, neutral and reverse. In this example
embodiment, the engaged neutral and transition between forward, reverse and
optionally neutral can be implemented by using an output planetary gear set
such
as planetary gear set 104 of Figure 9. Although planetary gear set 104
illustrates a
ring gear 108 driven by a single sun gear 106 rotating against three planet
gears
107, this is but one example of a planetary gear set that may be used in
connection
with some embodiments of the present invention. For example, in other
embodiments, more or fewer planet gears 107 can rotate around sun gear 106 and
engage ring gear 108.
In an example embodiment in which a transmission, such as, for example,
transmission 100 of Figure 1A or transmission 100' of Figure 1B, is in a
configuration which reverses the torque flow path, transmission input
interface 105
acts as the transmission output interface while transmission output interface
170
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CA 02736815 2011-04-14
acts as the transmission input interface. In such a case, and as disclosed in
Figure
9, transmission input interface 170 can be extended through transmission 100
and
connected to input sun gear 106 of planetary gear set 104, while transmission
output interface 105 can be connected to planet gears 107 which rotate against
sun
gear 106. The transmission output interface 105 may be connected to each of
planet gears 107 by using a planet carrier (not shown) which can cause each of
planet gears 107 to have an identical rotation.
Each of planet gears 107 also engages ring gear 108. Further, sun gear 106 and
planet gears 107 can also be in constant engagement with each other, and thus
io place the input RPMs from new transmission input interface 170 in conflict
with the
output RPMs of new transmission output interface 105. Thus, when transmission
100 is run with a reversed torque flow and sun gear 106 and planet gears 107
are
of equal sizes, it can be seen that when the input RPMs of sun gear 106 are of
an
equal magnitude as the output RPMs of planet gears 107, sun gear 106 and
planet
gears 107 have a negligible, and possibly zero, net output that is provided to
ring
gear 108, thereby placing the transmission in a neutral state while
maintaining
engagement between sun gear 106 and planet gears 107 of planetary gear set
104, and between drive gears 121a-f and driven gears 132a-c. To then shift the
transmission out of a neutral output state, the drive and/or driven gear
positions
may be adjusted to vary the input and output RPMs. In this manner, the angular
velocity of transmission output interface 105 and planet gears 106 can change,
to
shift the transmission into either a forward or reverse gear.
For example, if transmission input interface 170 is maintained at a constant
angular
velocity, by increasing the angular velocity of planet gears 107, the angular
velocity
of planet gears 107 becomes greater than the angular velocity of sun gear 106,
thereby causing ring gear 108 to rotate in a first direction, clockwise for
example,
such that transmission shifts into a forward gear. Conversely, if the angular
velocity of planet gears 106 is decreased, the angular velocity of planet
gears 107
becomes less than the angular velocity of sun gear 106, such that ring gear
108
then rotates in a second direction, counterclockwise for example, such that
the
transmission shifts into a reverse gear. Thus, by merely adjusting the
rotational
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CA 02736815 2011-12-22
speed of planet gears 107 and/or sun gears 106, planetary gear set 104 can
provide a neutral, forward, or reverse state without the application of an
external
force, e.g., with clutch plates or bands, for example, to constrain the
rotation of one
or more of ring gear 108, planet gears 107, or sun gear 106.
While the illustrated example embodiment discloses that transmission input
interface 170 is coupled to sun gear 106 and transmission output interface 105
is
coupled to planet gears 107, it will be appreciated that in other embodiments,
the
relationship may be changed such that the input interface is coupled to sun
gear
106 and the output interface is coupled to the planet gears 107. Further,
while
fo example embodiments may include a sun gear 106 and planet gears 107 which
are
of the same size, in other embodiments, sun gear 106 and planet gears 107 may
have different respective sizes. For example, sun gear 106 may be larger than
the
one or more planet gears 107, although in other example embodiments, sun gear
106 may be smaller than planet gears 107. It will also be appreciated that
even
where the sun gear 106 and planet gears 107 differ in size, planet gears set
104
can produce a neutral output state as disclosed herein, inasmuch as the
angular
velocities of sun gear 106 and planet gears 107 have associated linear
velocities at
the point of engagement between sun gear 106 and planet gears 107 which may
be of equal but opposite magnitudes.
While the example disclosed embodiments depict drive and driven gears as spur
and ring gears, respectively, it should be appreciated that in other
embodiments,
the drive and/or the driven gears are not necessarily spur or ring gears. For
example, in one embodiment, the driven gears are spur gears rather than ring
gears. In such an embodiment, the driven spur gears may be radially moveable
to
maintain engagement with radially movable drive spur gears, and are optionally
movable along predetermined axes that are offset at substantially equal
angular
intervals around a common central axis. For example, three driven spur gears
may
each be offset at, and translate radially along translation paths that are
offset with
respect to the translation paths of other driven spur gears at about one
hundred
twenty degree angular intervals. Moreover, in such an example embodiment in
which the drive and driven gears are each spur or helical gears, the drive
gears
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CA 02736815 2011-04-14
may orbit around the external perimeter of the driven gears such that the
perimeter
of the driven gears defines a virtual gear which is maintained in
substantially
constant engagement with the drive gears. In other example embodiments, the
drive gears orbit inside the periphery formed by the driven gears, such that
the
internal perimeter of the driven gears defines a virtual gear which is
maintained in
substantially constant engagement with the drive gears.
A schematic illustration of an example embodiment in which drive gears engage
multiple driven gears, which may comprise spur or helical gears, for example,
is
provided in Figure 10A. In the illustrated embodiment, four driven gears 532a-
d are
io offset at equal ninety degree angular intervals. In addition, the
illustrated
embodiment discloses four drive gears 520a-d, also offset at equal angular
intervals, which are in dead center engagement with driven gears 532a-d. In
this
embodiment, therefore, drive gears 520a-d engage driven gears 532a-d at top
dead center every ninety degrees. In some embodiments, and as disclosed
herein,
drive gears 520a-d and driven gears 532a-d may be configured to move radially
inward and/or outward. For example, drive gears 520a-d may move inward or
outward along such that the lever lengths associated with drive gears 520a-d
can
increase or decrease, and such that the orbital path drive gears 520a-d follow
as
they orbit around the intersection of their levers correspondingly increases
or
decreases. Similarly, driven gears 532a-d may move inward and/or outward along
translation paths which pass through the intersection of the levers and the
center of
each driven gear 532a-d. Accordingly, in the illustrated embodiment, driven
gears
532a-d can translate along translation paths offset from each other at ninety
degree
intervals. In this manner, driven gears 532a-d may translate radially to
maintain
engagement with drive gears 520a-d as drive gears 520a-d also translate
radially.
Notably, in some embodiments, only drive gears 520a-d orbit and translate,
while
driven gears 532a-d translate but do not orbit about an external central axis.
As noted above, where four drive gears 520a-d engage four driven gears 532a-d,
dead center engagement occurs every ninety degrees as each drive gear 520a-d
enters into engagement with one of the respective driven gears 532a-d. In the
embodiment illustrated in Figures 2A-G, it can be seen that in an embodiment
with
CA 02736815 2011-04-14
three driven gears and two drive gears, top dead center engagement can occur
every sixty degrees rather than every ninety degrees. Thus, with about thirty-
seven
percent fewer gears, the frequency of dead center engagement is increased by
one
hundred and fifty percent.
A similar illustration is shown in Figure 10B, in which three drive gears 520a-
c are
used to drive four driven gears 532a-d. As shown in the illustrated
embodiment, by
removing one drive gear from the embodiment illustrated in Figure 10A, and
thus
reducing the total number of gears by about twelve percent and the number of
drive
gears by twenty-five percent, engagement frequency can be increased to every
io thirty degrees, for an increase of three hundred percent over the
embodiment
illustrated in Figure 10A.
The resulting change in engagement frequency caused by changing the numbers
of drive and driven gears can also be explained by a variation of the Vernier
principle used for measurement devices such as calipers. In the case of
calipers,
the Vernier principle is a basic measurement principle which takes an equal
distance, such as one-tenth of an inch, and divides it into an odd number of
increments, e.g., twenty-five, and an even number of increments, e.g., twenty-
four.
Based on the alignment of the increments, a distance can be measured. For
example, the lines of twenty-four increments line-up with the lines of twenty-
five
increments every thousandth of an inch.
In a similar manner, example embodiments of the present invention can be
employed to vary the number of parts needed to maintain a substantially
constant
engagement of drive and driven gears by offsetting input drive members and the
output driven members at different angular intervals and/or by using different
numbers of drive and driven members. No single ratio of drive-to-driven
members
is, however, required and a particular ratio will be a matter of design choice
depending on the demands of any particular application. Nevertheless, it can
be
seen that the number of drive and driven members can affect the engagement
frequency between drive and driven members.
For example, Table 1 provides an exemplary indication of the manner in which
the
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CA 02736815 2011-04-14
numbers of drive and driven members can affect engagement frequency. In
particular, Table 1 provides the frequency of dead center engagement for
varying
numbers of drive and driven members that are each offset at equal intervals.
While
Table 1 references the frequency of dead center engagement in terms of numbers
of drive and driven gears, it will be appreciated in view of the disclosure
herein that
the frequency of engagement can be determined by the number of different
positions of drive and driven gears, and not merely by the total number of
gears.
For instance, as noted above with reference to Figures 1A-B, a transmission,
e.g.,
transmission 100 or 100', includes three driven gears and six drive gears,
although
io the drive gears are positioned on two axes, such that there are only two
different
angular positions of the drive gears around a circle. As discussed above, dead
center engagement occurs in such an example every sixty degrees. As shown in
Table 1, this result is consistent with a transmission which has three driven
gears
and two drive gears or a transmission which has three driven gears and six
drive
gears.
In another example, as shown in Table 1 and as disclosed herein, three drive
gears
can engage with four driven gears every thirty degrees. This engagement can be
increased, however, by changing the number of drive and driven members. For
instance, if five drive gears are used to engage six driven gears, one drive
gear will
enter into dead center engagement with a driven gear every twelve degrees.
During this time, other drive gears will also be in various other stages of
engagement and disengagement with other driven gears. In addition, and as
shown in Table 1, adding just one more drive member can actually decrease
engagement frequency such that it occurs only once every sixty degrees.
As further shown in Table 1, the most frequent engagement between drive and
driven gears tends to occur, in general, when there is an odd-and-even ratio
between drive and driven gears, or when the ratio can be factored down to an
odd-
and-even ratio. For example, for the numbers provided in Table 1, eight driven
gears are engaged at top dead center most frequently when there are nine drive
gears, i.e., every five degrees, and almost as frequently, i.e., every six and
a half
degrees, when there are seven drive gears. The most frequent engagement for an
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CA 02736815 2011-04-14
even number of drive gears with eight driven gears is, however, every fifteen
degrees, which happens when there are six drive gears. However, the same
frequency can be obtained with only three drive gears, or half the number of
drive
members.
Driven Gears
1 2 3 4 5 6 7 8 9
1 3600 180 120 90 72 60 51.43 45 40
2 180 180 60 900 36 60 25.71 45 40
3 120 60 120 30 24 60 17.14 15 20
4 90 90 30 90 18 30 12.86 45 40
C~ 5 72 36 24 18 72 12 10.29 90 8
m
6 60 60 60 30 12 60 8.57 15 20
C)
7 51.43 25.71 17.14 12.86 10.29 8.57 51.43 6.43 5.71o
8 45 45 15 45 9 15 6.43 45 5
9 40 20 40 10 8 20 5.71 5 400
Table 1
Referring now to Figures 11A-B, various aspects of another exemplary
embodiment of a transmission 600 are disclosed. As with other embodiments
disclosed herein, the embodiment disclosed in Figures 11A-B can include gears
or
other members which are arranged to maintain substantially constant engagement
between drive and driven gears that determine and cause changes to the gear
ratios of transmission 600. Moreover, by maintaining substantially constant
engagement between drive and driven gears, transmission 600 can allow a
substantially constant connection between the drive and driven gears, between
the
driven gears and the power source, and between the power source. In some
embodiments, the substantially constant connection may be maintained even
without an external source suppressing the rotation of the gears, while some
embodiments can include a clutch or other mechanism for suppressing the
rotation
of the drive and/or driven gears. In either example, however, the transmission
can
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CA 02736815 2011-04-14
employ the general principles of operation and synchronization as disclosed
herein.
In the illustrated embodiment, transmission 600 includes an input shaft 601
which
is connected to a power source, and thus acts as an interface between the
power
source and transmission 600. For example, the power source may be an engine or
motor. Such engine or motor may be associated with a motor vehicle, an
elevator,
conveyor system, exercise equipment, a lathe, or virtually any other system or
device that operates in connection with some type of engine or motor.
Accordingly,
it should be appreciated that transmission 600 is not limited to use with a
moving
vehicle, or any other particular type of power source, but may instead be any
type
of power source from a wide variety of applications. More specifically,
transmission
600 may be used in any application where multiple gear ratios are desired.
In the illustrated embodiment, as input shaft 601 receives power from a power
source, it rotates about its own axis. To facilitate such rotation, input
shaft 601 can
be joumaled for rotation by using input bearing 602. Input bearing 602 may, in
some embodiments, be fixed in place by, for example, being secured to a
transmission housing and/or other structure(s).
Adjacent to input bearing 602, transmission 600 may include a reference ring
603
which can include an opening through which input shaft 601 extends. Reference
ring 603 is, in some embodiments, a reference gear as described herein and
which
is fixed such that it does not rotate as input shaft 601 is rotated. Reference
ring
603 may also be secured to the transmission housing (not shown), an input
housing 610, or otherwise supported. For instance reference ring 603 may be
directly secured to the transmission housing. In other embodiments, reference
ring
603 may be indirectly secured to the transmission housing by, for example,
being
connected to input bearing 602 which is in turn secured to the transmission
housing.
Optionally, an input housing 610 may be provided. In some example
embodiments, input housing 610 is fixed to input shaft 601 and is adapted to
rotate
and also cause the drive gears in transmission 600 to rotate. Input housing
610
may be fixed to input shaft 601 by, for example, welding, mechanical
fasteners, or
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CA 02736815 2011-04-14
some other suitable attachment means. Accordingly, as input shaft 601 rotates,
the attached power supply also causes input housing 610 to rotate. In the
illustrated embodiment, input housing 610 may further include multiple
openings
near the outer perimeter which have bearings inserted therein and which
receive
one or more drive shafts 604 which rotate therein. The openings may be
provided
in input housing 610 in any suitable manner. For instance, the holes may be
drilled
or reamed, cast or molded, or formed in any other suitable manner.
As further disclosed by Figure 11 A, timing gears 605 can be affixed to drive
shafts
604 and may also mate with reference ring 603. Timing gears 605 may comprise
1o spur or helical gears, for example, which engage reference ring 603, and
may
include involute gear teeth which mate with involute gear teeth on reference
ring
603. Consequently, as input housing 610 is rotated, for example by rotating
input
shaft 601, input housing 610 can cause timing gears 605 to rotate and orbit
around
reference ring 603 and thus rotate drive shafts 604. In this regard, at least,
timing
gears 605 can operate similar to the manner in which ratio reference gears 114
of
Figure 1A operate.
Pivot drive gears 611 (collectively illustrated as "A" gears in the example
embodiment of Figure 11 B) may also be fixed to drive shafts 604. Accordingly,
when drive shafts 604 rotate, pivot drive gears 611 also rotate. To facilitate
rotation
of drive shafts 604, input control links 613 may be positioned on each side of
pivot
drive gears 611 and can include openings and corresponding bearings to allow
for
support and/or rotation of drive shafts 604. Further, pivot drive gears 611
can mate
with drive gears 612 (collectively illustrated as "B" gears in the example
embodiment of Figure 11 B) which are rotated as pivot drive gears 611 rotate.
Input
control links 613 may further include openings and corresponding bearings that
receive a moon shaft (not shown) which rotates about an internal axis.
In the illustrated embodiment, input link control gears 606 can be mounted on
respective drive shafts 604 and positioned between input housing 610 and a
first
input control link 613. Input link control gears 606 can thus engage, and
rotate
3o around, a first tube gear 637 by, for example, using mating gear teeth,
which may
be involute in some embodiments. As disclosed herein, tube gear 637 may rotate
CA 02736815 2011-04-14
when a connected control tube 634 rotates, thereby causing input link control
gears
606 to rotate. In some example embodiments input control links 613 are coupled
to a shaft (not shown) which rotates as input link control gears 606 rotate,
such that
as a result of input link control gears 606 rotating, input control links 613
rotate,
further causing cause drive gears 612 to at least partially orbit around pivot
drive
gears 611. Accordingly, drive gears 612 may be moved such that they translate
around pivot drive gears 611. Thus, drive gears 612 translate inward and/or
outward along a curved path around pivot drive gears 611, thereby moving
radially
with respect to an axis aligned with the center of input housing 610. This
inward or
io outward movement of drive gears 612 around pivot drive gears 611 can also
change the orbital path followed by drive gears 612 as timing gears 605 cause
drive gears 612 to orbit. Consequently, the lever length between drive gears
612
and the axis about which drive gears 612 orbit, and the length of the orbital
path of
drive gears 612, also increases or decreases.
As disclosed herein, input control links 613 can be coupled to a shaft (not
shown)
which rotates input control links 613. In some example embodiments the shaft
is
offset from the center of input control links 613 such that when input control
links
613 rotate about the shaft, the position of drive gears 612 which are
connected to
input control links 613 changes. In the example arrangement illustrated in
Figure
11A, for example, input control links 613 are arranged in an inward
configuration
such that drive gears 612 are in an inner position in which the radial
position of
drive gears 612 is inside the radial position of pivot drive gears 611. More
particularly, the distance between the drive gears 612 and the axis about
which
drive gears 612 orbit, i.e. the lever length, is less than the distance
between that
same axis and pivot drive gears 611. As drive gears 612 translate around
respective pivot drive gears 611, the position of drive gears 612 can change.
For
instance, drive gears 612 may translate, in one embodiment, radially such that
the
lever length changes while translating along a curved path around pivot drive
gears
611 to an outer position, such that the radial position of drive gears 612 is
outside
the radial position of pivot drive gears 611. More particularly, in an outer
position,
the distance between drive gears 612 and the axis about which drive gears 612
orbit, i.e. the lever length, is greater than the distance between that same
axis and
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CA 02736815 2011-04-14
pivot drive gears 611. For example, in the example arrangement of Figures 11A-
B,
upon causing drive gears 612 to translate around pivot drive gears 611, they
can
move from an inner position to an outer position. An example outer position of
a
moon drive gear 612 is shown as moon drive gear 617, illustrated in phantom
lines,
in Figures 11A-B.
Although a single outer position of moon drive gear 617 is illustrated, each
moon
drive gear 612 in transmission 600 can move to a corresponding outer position,
such that moon drive gear 617 is illustrative of an outer position of each of
drive
gears 612. Moreover, while Figures 11 A-B illustrate only two positions of
drive
io gears 612, this arrangement is illustrative only. In fact, drive gears 612
can, in
some example embodiments, move to any position around pivot drive gears 611,
such that the length of the orbital path followed by drive gears 612 as they
orbit
around an axis aligned with input shaft 601 can be varied between a very
large,
possibly infinite, number of lengths. As discussed herein, in some
embodiments,
engagement with driven gears 614 can be maintained throughout changes in the
orbital path of drive gears 612. In other embodiments, engagement of drive
gears
612 and driven gears 614 occurs only at discrete orbital paths, thereby
providing
discrete gear ratios within transmission 600. As noted previously, however,
embodiments of the present invention allow discrete gear ratios to be
maintained
with very little corresponding change in the orbital path. For example, each
gear
ratio may be maintained at a whole tooth increment. Consequently, very little
translational movement is required to effect a gear ratio change. As a result,
the
translation of driven gears 614 around pivot drive gears 611 may provide, for
example, ten, twenty, thirty, or even more different discrete gear ratios.
Drive gears 612 can also mate with and engage driven, output moon gears 614
(collectively illustrated as "D" gears in Figure 11 B). As a result, when moon
gears
612 rotate, e.g., as a result of the rotation of pivot drive gears 611, output
moon
gears 614 can, in the illustrated example embodiment, also be rotated. Where
input, drive gears 612 and output driven gears 614 have the same radius,
rotating
3o drive gears 612 may thus rotate driven gears 614 at the same angular
velocity at
which input moon gears 612 rotate, although it is not necessary that drive
gears
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CA 02736815 2011-04-14
612 and driven gears 614 have the same radii. In either case, when drive gears
612 engage driven, output moon gears 614, output moon gears 614 also rotate
about their respective central axes. In some embodiments, engagement between
drive gears 612 and driven gears 614 occurs on an alternating basis as drive
gears
612 follow an orbital path. For example, driven gears 614 may be adapted such
that they do not collectively orbit around an external axis, while drive gears
612 do
have an orbit around an external axis. In such an example, as drive gears 612
orbit around the external axis, each of drive gears 612 can enter into and out
of
engagement with each moon driven gear 614. Consequently, each driven gear
io 614 is being alternately engaged by the various drive gears 612. Moreover,
in
some examples, drive gears 612 and driven gears 614 are arranged such that at
any stage of the orbital motion of drive gears 612, at least one of drive
gears 612 is
engaged with at least one of driven gears 614. In this manner, drive gears 612
can
maintain substantially constant engagement with driven gears 614.
In this example embodiment, driven gears 614 are also connected to output
control
links 615. Output link control links 615 can further be connected to output
link
control gears 640 which rotate around a second tube gear 636 whose rotation is
controlled by a control tube 681. Accordingly, as second tube gear 636
rotates,
output link control gears 640 may be rotated by tube gear 636. Further, output
link
control gears 640 can be coupled with output control links 615, such that as
output
control link gears 640 rotate, output control links 615 are also rotated.
Output
gears 614 may further be coupled to output control links 615, by a shaft
offset from
the center of output control links 615, for example. In one example, as output
control links 615 rotate, output control links 615 thereby cause driven gears
614 to
translate along a curved path around output pivot gears 607 (collectively
illustrated
as "C" gears in Figure 11 B).
In some embodiments, and as disclosed herein, rotation of control tube 634
causes
first tube gear 637 to rotate relative to the rotation of input shaft 601,
while rotation
of control tube 681 causes second tube gear 636 to rotate. As a result, as
control
tubes 634, 681 rotate, each of drive gears 612 and driven gears 614 can rotate
at
least partially around respective pivot gears 607, 611. Thus, drive gears 612
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CA 02736815 2011-04-14
and/or driven gears 614 can move radially inward and outward with respect to
an
axis about which drive gears 612 orbit, such as an axis aligned with input
shaft 601,
such that the lever length between drive gears 612 and input shaft 601
increases or
decreases. If the rotations of control tubes 634, 681 are synchronized, such
that
they occur at the same time or at about the same time, the rotation of control
links
613, 615 can also thus be synchronized, thereby also synchronizing the radial
translation of drive gears 612 and driven gears 614. In particular, output
control
link gears 640 and input control link gears 606 can be rotated by second tube
gear
636 and first tube gear 637, respectively such that the radial positioning of
driven
1o gears 614 is controlled at about the same time as the radial positioning of
drive
gears 612. Consequently, drive gears 612 and driven gears 614 can maintain
alignment for substantially constant engagement as the distance between the
central axis of input shaft 601 and drive gears 612 and driven gears 614
changes.
Stated another way, as the lever length of drive gears 612 changes and the
length
of the orbital path of drive gears 612, e.g. around input shaft 601, changes,
drive
gears 612 rotate, e.g., around their respective central axes, and maintain
substantially constant engagement with driven gears 614 which also move a
corresponding radial distance. As discussed previously with respect to example
transmissions 100 and 100', such engagement can be maintained throughout a
gear ratio change, e.g., in transmission with sliding gear ratio changes, or
at
discrete gear ratios, e.g., in a transmission with stepped gear ratio changes.
With
respect to transmission 600 of Figures 11A-B, in either case, the outermost
portions of driven gears 614, i.e. the portions of driven gears 614 which are
the
greatest distance from the center of control tube 634, define a virtual gear
651,
illustrated in phantom lines in Figure 11 B.
As best illustrated in the example embodiment of Figure 11 B, when input
housing
610 rotates, drive gears 612 may also orbit around the center of input housing
610,
which in some examples is aligned with the center of input shaft 601 and/or
control
tubes 634, 681. Accordingly, drive gears 612 follow an orbital path which
extends
3o around the outer perimeter of driven gears 614, along the edges of driven
gears
which are the furthest distance from the center of input housing 610, although
in
other embodiments, drive gears may follow an orbital path around the interior
of the
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CA 02736815 2011-04-14
driven gears, for example, along the edges of driven gears 614 which are
closest to
the center of input housing 610. Accordingly, driven gears 614 move radially
outward, thereby increasing the distance between their outer edges and the
center
of input housing 610, drive moon gears 612 can be synchronously, or about
synchronously, moved radially, so that a substantially constant engagement
between drive gears 612 and driven gears 614 is thus maintained. Stated
another
way, as driven gears 614 translate radially outward, the size of virtual gear
651
increases, and drive gears 612 can correspondingly translate radially outward
at
about the same time to maintain substantially constant engagement with virtual
io gear 651. Such engagement may be maintained throughout a gear ratio change,
such as in a transmission which maintains constant engagement between drive
gears 612 and driven gears 614 as drive gears 612 and driven gears 614 slide
radially inward or outward. Alternatively, engagement between drive gears 612
and driven gears 614 may be temporarily interrupted when gear ratio changes
are
made, such as in a transmission which steps between gear ratios defined at
discrete locations of the drive gears 612 and the driven gears 614,.
As disclosed herein, whether a transmission slides or steps between gear
ratios,
the transmission can provide essentially the same results. For example, losses
in
momentum or torque spikes may be negligible in either a sliding or stepped
transmission that creates gear ratio changes by changing the radial distance
between drive gears 612 and the axis about which drive gears 612 orbit. In the
illustrated embodiment, for example, drive gears 612 rotate and orbit around
an
axis aligned with the center of input housing 610, for example. Consequently,
control links 613, 615 and pivot gears 607, 611 are collectively and
individually
examples of structural implementations of means for synchronizing drive and
driven gears to maintain substantially constant engagement between drive and
driven gears as they move radially to produce any of a very large number,
possibly
infinite number, of gear ratios.
In the example arrangement which includes five driven gears 614 virtual gear
651
is generally pentagonal in shape, with rounded corners which are aligned with
driven gears 614. In light of the disclosure herein, it will be appreciated,
however,
CA 02736815 2011-12-22
that the shape of virtual gear 651 can vary. In general, for example, as more
driven
gears are added, the shape of virtual gear 651 will more closely resemble a
circle.
In another embodiment, the shape of the virtual gear can always be considered
as
being circular, with the driven gears positioned at the vertexes of a polygon
circumscribed by the circular virtual gear. For example, in the illustrated
embodiment, virtual gear 651 may be circular with each of drive gears 618
positioned at a vertex of a regular pentagon circumscribed by virtual gear
651.
Moreover, as driven gears 614 move radially outward or inward, the size of
virtual
gear 651 correspondingly increases or decreases. Accordingly, drive gears 614
1o can be positioned in any of a variety of radial positions so as to define a
large,
possibly infinite, number of different sizes of virtual gear 651.
As disclosed previously, when drive gears 612 are moved to an outward
position,
such as the position of moon drive gear 617, the length of the orbital path
taken by
the drive gears 612 increases. In this manner, a constant rotational input,
which
causes drive gears 612 to orbit around an external axis, such as an axis
aligned
with the center of input housing 610, for example, at a constant angular
velocity,
will thus cause drive gears 617 to have a greater linear velocity than drive
gears
612, at the positions illustrated in Figures 11A-B. This is because drive
gears 617
follow a longer orbital path than drive gears 612 and, accordingly, must
travel a
greater arc length per rotation. As drive gears 612 mate with, and thereby
drive,
driven gears 614, this increased linear velocity is shared by driven gears 614
at the
point of engagement. As a result, driven gears 614, which may rotate about
their
centers but not orbit, experience increased linear and angular velocity.
Consequently, an increase in gear ratio is realized. It will also be
appreciated that
a gear ratio change can be realized by translating drive gears 612 between any
two
positions on the path along which drive gears 612 move radially outward. For
example, moving drive gears 612 between any two points on path 660 can cause a
corresponding increase or decrease in gear ratio. Moreover, inasmuch as path
660
can have any number of discrete or non-discrete points at which drive gears
612
can be rotated, drive gears 612 can follow any of a large, and possibly
infinite,
number of different orbital paths such that a large, and possibly infinite,
number of
gear ratios can be realized.
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CA 02736815 2011-12-22
The relation of the number of drive gears to the number of driven gears may be
varied in any suitable manner. For instance, in one embodiment, there are the
same number of drive and driven gears. In other embodiments, there are
different
numbers of drive and driven gears. As a further example, it is contemplated
that an
even number of input moons be used with an odd number of output moons, or vice
versa. For instance, as described previously, three output, driven gears may
be
used with two drive gears. In another embodiment, such as that disclosed in
Figure 11 B, five driven gears are used in connection with eight drive gears.
More specifically, Figure 11 B illustrates a partial cross-section of the
transmission
io 600 illustrated in Figure 11A in which eight drive gears 612 (collectively
labeled as
"B" gears) engage five driven gears 614 (collectively labeled as "D" gears).
In the
illustrated embodiment, drive moons 612 and driven moons 614 are positioned at
equally spaced angular intervals of forty-five degrees and seventy-two
degrees,
respectively, although any other particular number of drive gears and/or
driven
gears can be used, and the respective moon drive and driven gear spacings can
be
varied as well. Drive gears 612 have various rotations, including rotations
about
axes passing through their respective centers and a collective orbit about an
axis
passing through the center of input housing 610. As a result of the orbital
movement of drive gears 612, drive gears 612 are constantly entering into and
out
of various degrees of engagement with driven gears 614 during the various
stages
of the orbital movement of drive gears 612. For example, in the illustrated
embodiment, and as reflected in Table 1, one of the eight drive gears 612 will
come
into dead center engagement with one of the five driven gears 614 every nine
degrees of rotation of input shaft 601. As disclosed in Figure 11 B, while one
or
more of drive gears 612 engages one or more of driven gears 614, other drive
gears 612 and driven gears 614 may also be in various stages of engagement.
In the embodiment illustrated in Figure 11A, driven gears 614 also engage
output
pivot gears 607 (collectively labeled as "C" gears in Figure 11 B).
Consequently,
when driven gears 614 are engaged and rotated by drive gears 612, driven gears
614 cause output pivot gears 607 to rotate about their respective axes. Each
output
pivot gear 607 and be further coupled to a pivot shaft 620. Optionally, pivot
shafts
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CA 02736815 2011-04-14
620 pass from output pivot gears 607 through an output housing 616, e.g., by
using
holes and bearings provided in output housing 616. Output housing 616 may, in
some embodiments, also be connected to the transmission housing (not shown).
As illustrated in Figure 11A, pivot shafts 620 can extend to, and connect
with,
output gears 621, which are, in this example embodiment, star gears.
Consequently, as any of output pivot gears 607 is rotated by a moon driven
gear
614, pivot shaft 620 causes a corresponding output gear 621 to rotate. Output
gears 621 may, in turn, engage an output planetary ring gear 622. As each
output
gear 621 can engage output planetary ring gear 622, the rotation of each
output
1o gear 621 is linked such that each output gear 621 maintains an identical
rotation
about its respective center. Linking output gears 621 thereby also links the
rotation
of pivot shafts 620, pivot gears 607, and moon driven gear 614, such that each
moon driven gear 614 maintains the same rotation about its respective central
axis,
regardless of whether and to what degree the moon driven gear 614 is being
engaged by a moon drive gear 612.
In this embodiment, planetary ring gear 622 includes an internal gear profile
which
engages planet gears 623. As a result, the rotation of output star gear 621
can
cause planetary ring gear 622 to rotate and thereby engage and rotate planet
gears
623. Planet gears 623 may further be connected to a ratable output yoke 630,
for
example by using extensions 625. As extensions 625 are rotated by planet gears
623, output yoke 630 is also rotated. This arrangement enables output of the
power from transmission 600. Moreover, transmission 600 can be connected to a
load or power sink in any suitable manner, such that output yoke 630 can also
act
as an interface for providing the power output of transmission 600.
Optionally, an input gear 624, which can be a sun gear, for example, may be
affixed to input shaft 601 and can engage each of planet gears 623. The output
planetary ring gear 622 can, in this arrangement, relate the power input into
transmission 600 to the rotation of output star gears 621, which is an
intermediate
output of transmission 600. In particular, when planet gears E323 and input
sun
gears 624 are of the same size and planet gears 623 are rotated about their
respective central axes by ring gear 622 at the same angular velocity as the
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rotation of input sun gear 624, planet gears 623 are in direct conflict with
input sun
gear 624, thereby resulting in negligible, possibly zero, output at output
yoke 630.
In other words, transmission 600 is in a neutral output state although drive
gears
612 remain engaged with driven gears 614. In this way, an engaged neutral
state
is implemented, notwithstanding that the drive and driven gears remain engaged
and continue their respective rotations and orbits. Thus, transmission 600 may
be
in a neutral output state without necessitating disconnection of the power
source
from the load, and without necessitating disconnection of the drive and driven
gears, and without requiring a mechanism to slow or stop the rotation of any
drive
to or driven gear within transmission 600. To the extent output gears 621
cause
planet gears 623 rotate faster than input sun gears 624, output yoke 630
produces
a forward output for transmission 600, while a slower rotation of planet gears
623
as compared to the rotation of input sun gear 624 results in a reverse output.
Although input star gear 621 and output planet gears 623 are, in an example
embodiment, each of the same size, this feature is not necessary. In other
example embodiments, for example, the respective sizes of input star gear 621
and
output planet gears 623 can be varied. Where input star gear 621 and output
planet gears 623 are of different sizes, transmission 600 may be placed in a
neutral
output state notwithstanding different angular velocities of output planet
gears 623
and input star gear 621.
As discussed herein, transmission 600 can further include a mechanism for
changing between gear ratios in either discrete or in substantially non-
discrete,
possibly infinitely small, increments. Consequently, transmission 600 can step
or
slide between gear ratios, thereby providing a variable speed transmission
that
does not rely on the use of only a small group of discrete gear ratios and
which
changes gear ratios without a torque spike, or without a torque spike large
enough
to damage the transmission or an associated drive train. In the illustrated
embodiment, a shift lever 631 is hinged at pivot 632. As shift lever 631 is
rotated
about pivot 632, the rotation of shift lever 631 displaces shift control
bearing 633
which is positioned around a control tube 634 that is, in this embodiment,
coaxial
with input shaft 601.
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In an example embodiment, control tube 634 is adapted to generally maintain a
rotation which is identical to the rotation of input shaft 601. A pilot
bearing (not
shown) may thus be fixed into the inner portion of shift control bearing 633
and to
control tube 634 and input shaft 601 such that the pilot bearing rotates with
the
control tube 634 and the input shaft 601. The pilot bearing may be adapted to
travel along a control groove 635 formed in control tube 634, and fixed within
a
groove (not shown) within input shaft 601. Control groove 635 and the groove
in
input shaft 601 may, in one example embodiment, have different paths. As a
result, the forward-and-back movement of shift control bearing 633 follows the
path
to outlined by control groove 635 and causes control tube 634 to have a
rotation
which is different than the rotation of input shaft 601. Consequently, control
tube
634 rotates relative to the rotation of input shaft 601. Control groove 635
may
comprise any suitable path(s). For instance, in the illustrated embodiment,
control
groove 635 has a spiral, stretched "S" configuration, although this is but one
possible configuration. The groove in input shaft 601 may also have any
suitable
path(s). For instance, in one example, the groove in input shaft 601 is
straight.
In one example embodiment, shift lever 631 may be coupled to the exterior of
shift
control bearing 630 at a second pivot 680. Thus, as shift lever 631 is rotated
about
pivot 632 and shift control bearing 633 is displaced, the rotation of shift
lever 631
causes second pivot 680 to also move axially with respect to control tube 634.
Second control tube 681 may, in some example embodiments, also be positioned
around shift control bearing 633 and, optionally, around control tube 634.
Second
pivot 680 may be positioned within a second control groove 682 formed in
second
control tube 681 such that as second pivot 680 follows along second control
groove
682 as second pivot 680 moves axially with respect to control tube 634. As a
result, the forward-and-back movement of shift control bearing 633 also causes
second pivot 680 to follow the path defined by second control groove 682.
Second
control groove 682 may also comprise any suitable path(s). For instance, in
one
embodiment, second control groove 682 has a configuration which is similar to
that
of control groove 635. By way of example, if control groove 635 has a helical
configuration, second control groove 682 can also have a helical configuration
which is positioned directly over, or offset from, control groove 635.
CA 02736815 2011-12-22
Shift control bearing 633 and second pivot 680 can further be linked to input
link
control gears 606 and output link control gears 640, respectively.
Consequently,
the forward-and-back movement of shift control bearing 633 and second pivot
680
may cause control tubes 634, 681 to rotate, or to rotate relative to input
shaft 601,
thereby causing input link control gears 606 and output link control gears 640
to
rotate. In particular, as shift control bearing 633 moves axially along
control tube
634, such that control tube 634 rotates relative to input shaft 601, control
tube 634
rotates. Similarly, as second pivot 680 moves axially along second control
tube
681, second control tube 681 rotates. Control tube 634 can also be coupled to
io tube gears 636, 637. As a result, when control tube 634 rotates relative to
input
shaft 601, tube gears 636, 637 can also rotate, thereby also causing input
link
control gears 606 and output link control gears 640, to rotate. As input link
control
gears 606 rotate, input control links 613 rotate simultaneously therewith,
also
causing drive gears 612, which are mounted thereto, to synchronously translate
around pivot drive gears 611, for example along translation path 660, thereby
changing the lever associated with drive gears 612. In a similar manner,
second
control tube 681 can be coupled to tube gear 636 such that as second control
tube
681 rotates, tube gear 636 can also rotate, thereby causing output link
control
gears 640 to rotate. As output link control gears 640 rotate, output control
links 615
are also thereby rotated. Output control links 615 may further be coupled to
driven
gears 614 which then are also caused to translate around output pivot gears
607,
for example, along translation path 661. Consequently, control tubes 634, 681,
tube gears 636, 637, link control gears 606, 640, and control links 613, 615,
are
collectively and individually examples of structural implementations of means
for
synchronizing drive and driven gears to maintain substantially constant
engagement between drive and driven gears as they move radially to produce any
of a large number of non-discrete gear ratios.
By using control tubes 634, 681, tube gears 636, 637, control links 613, 615,
and/or
link control gears 606, 640, or any other equivalent structure, drive gears
612 and
driven gears 614 can thus be synchronously moved in one or more radial
directions
with respect to the axis about which drive gears 612 orbit, although it will
be
appreciated that in other embodiments control tubes 634 and 681 are rotated
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independently of each other. This relation may further increase or decrease
the arc
length which drive gears 612 must travel as they orbit. As disclosed herein,
this
increased or decreased arc length increases or decreases a linear velocity
associated with drive gears 612, thereby also increasing or decreasing the
output
of driven gears 614 which have a corresponding linear velocity at a point of
engagement and thereby also rotate at a corresponding angular velocity.
Moreover, as drive gears 612 may move to any location around pivot drive gears
611, they can alternately be located in a large number of discrete locations,
or
possibly at any of an infinite number of non-discrete locations, thereby also
io providing a large number, and possibly an infinite number, of orbital arc
lengths and
gear ratios as disclosed herein.
In addition, the synchronous movement of input link control gears 606 and
output
link control gears 640, by shift lever 631, pivot 632, second pivot 680, and
control
bearing 633, maintains input moon gears 612 in engagement with output moon
gears 614, thereby maintains substantially constant engagement as the arc
length
of the orbit of input moon gears 612 changes. In particular, substantially
constant
engagement is maintained as the lever length changes, so that the arc distance
increases as the lever increases, and thereby causes output moon gears 614 to
rotate at a greater angular velocity. Similarly, if the lever length changes
such that
the lever length decreases, the arc length of the orbital path also decreases,
thereby causing output moon gears 614 to rotate at a lesser angular velocity.
According to one embodiment, transmission 600 maintains a connection between
drive gears 612 and input shaft 601 during changes in gear ratio. According to
an
alternative embodiment, however, the rotation and/or orbital motion of drive
gears
612 may be decoupled from the rotation of input shaft 601 for at least a short
time
while a gear ratio change is made. For instance, similar to transmission 100'
of
Figure 1 B, transmission 600 may include one or more clutches (not shown)
which,
when engaged, cause the orbital and/or rotational motions of drive gears 612
to
cease. For instance, a clutch may be positioned between input shaft 601 and
input
3o housing 610. Consequently, as input shaft 601 rotates, input housing 610
does not
rotate when the clutch is engaged. As a result, when input housing 610 does
not
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rotate, drive gears 612 also do not rotate or orbit.
In view of the disclosure herein it will be appreciated that such a
positioning of a
clutch is merely exemplary only. In other embodiments, for instance, a clutch
(not
shown) may be additionally, or alternatively, placed between input housing 610
and
drive gear 612. In such an embodiment, engagement of the clutch may therefore
stop rotation of drive gear 612 as input housing 610 rotates, while continuing
to
allow drive gears 612 to collectively orbit.
As disclosed previously with respect to transmission 100 of Figure 1A, it may
also
be desirable, in some applications, to reverse the torque flow through
transmission
600. For example, in one embodiment, when transmission 600 enters into a
forward gear out of the engaged neutral, it may be desirable to have a low
torque
output. Accordingly, in other embodiments, the torque flow through
transmission
700 is reversed so that low torque out of neutral or other desirable torque
flow
characteristics are implemented. For example, in such an embodiment, power is
input through yoke 630 which then acts as the transmission input interface.
The
torque flow is reversed such that output moon gears 614 then act as the
driving
gears and engage and drive input moon gears 612, which become the driven
gears. As moon gears 614 then rotate, they also orbit and thereby cause input
shaft 601 to rotate and act as an interface for providing a power output.
In some cases, reversing the torque flow through transmission 600 may require
adjustments to facilitate the optional engaged neutral feature. Accordingly,
as
disclosed previously with respect to Figure 9, an engaged neutral can be
implemented by using a planetary gear set. In particular, the input at yoke
630 can
be carried through transmission 600 and connected to a sun gear which rotates
against various moon gears which are connected to the power output of shaft
601.
In this manner, the input and output RPMs are placed in conflict. As a result,
when
the linear velocities of the sun gear and planet gear are, at the engagement
point,
of an equal magnitude, the sun gear and planet gear collectively provide no
output
to a ring gear. Thus, transmission 600 is placed in an engaged neutral state.
If,
3o however, the input or output RPMs are increased over the other, a forward
output
can be obtained, possibly operating at low torque, or a reverse output can be
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CA 02736815 2011-12-22
obtained.
It can thus be seen that any of a variety of different types and numbers of
drive and
driven gears and gear sets can be used to vary the engagement frequency and
number of gears as necessary for a variety of applications. In fact, it is
contemplated that each application can have a different set of demands and the
benefits and features of the various types and numbers of gears will have to
be
weighed to determine which and how many drive and driven gears to use. For
example, in some embodiments, and as disclosed above with respect to Figures
1A-B, the driven gears may be ring gears which are driven by input spur gears.
In
1o other embodiments, a torque flow may be reversed through the transmission
such
that the driven gears become drive gears. In such embodiments, the ring gears
each have an internal arch which favors the orbit of the spur gears, and which
thereby allows the drive and driven gears to maintain engagement over a
respectively longer arc path than allowed by a spur or helical gear. Thus,
ring
is gears may be desirable to maintain a more constant engagement with fewer
total
components.
Ring gears may, however, be larger than the external, driven spur gears
illustrated
in Figures 11A-B. In contrast to the ring gears, the curvature of the external
driven
gears can contrast with the curved orbit of the drive gears, such that
engagement is
20 maintained over a shorter respective arc path than is maintained by a ring
gear.
Thus, if driven spur gears are used, in one example, more driven gears may be
used to increase the total engagement between the drive and driven gears.
Moreover, in applications where transmission size and/or weight are critical
design
parameters, it may be desirable to minimize the number and/or size of the
gears in
25 the transmission. In contrast, if the power source is supporting a large
load, it may
be desirable to have more gears. By way of example, where the number of drive
and driven gears are increased to eight and five, respectively, it is possible
to have
dead center engagement occur between a drive and driven gear about every nine
degrees along the orbit of the drive gears. In such an arrangement in which
the
30 orbit of the drive gears and the rotation of the input shaft are at the
same angular
velocity, the drive and driven gears accordingly enter into dead center
engagement
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about every nine degrees of input shaft rotation. In such an embodiment, at
dead
center engagement of one drive gear and one driven gear, the other drive and
driven gears can be in varying stages of engagement and disengagement. For
example, five of the drive gears may be in some degree of engagement while
only
three drive gears are not engaged with a driven gear. (See Figure 11 B). Thus,
five
drive gears can share the load among their gear teeth. In contrast, in the
embodiment illustrated in Figures 2A-G, in which two drive gear sets engage
three
driven gears, at dead center engagement, only one drive gear is engaged with
any
driven gear, such that the single engaged drive gear must then support the
full
load.
Now turning to Figure 12, a schematic illustration of still another embodiment
of a
power transform system 735 which can be used in a transmission as described
herein, is illustrated. Power transform system 735 includes multiple drive
gears
712 and driven gears 714 which can operate as discussed with respect to
Figures
1A-B and Figures 11A-B. In the illustrated embodiment, drive gears 712 are
connected to respective lever arms 716a-b. It will be appreciated, however,
that
lever arms 716 may be physical levers or virtual levers as discussed herein.
For
example, among other things, drive gears 712 may be connected via virtual arms
and, for example, can be connected to a carrier or other mechanism that allows
them to move radially inward and/or outward. Similarly, driven gears 714 may
be
configured to translate radially. As also disclosed above, drive gears 712
and/or
driven gears 714 can be configured to rotate about their respective centers
and can
optionally be configured to orbit around a central, external axis. For
instance, in the
illustrated embodiment, drive gears 712 can be angularly offset around the
perimeter of a circle and can orbit around an axis passing through the center
of that
circle.
As discussed above with respect to transmission 600 (Figures 11A-B), a
transmission according to some aspects of the present invention can include a
plurality of drive gears 612 and driven gears 614 which are aligned in a
single
plane, i.e., at a single axial location. In view of the disclosure herein, it
will be
appreciated that this is exemplary only. For instance, Figure 12 illustrates
an
CA 02736815 2011-04-14
example power transform system 735 in which multiple driving moon gears 712
can
engage and rotate multiple driven sun gears 714, where the drive gears 712 and
driven gears 714 are located in multiple, axially spaced planes.
In the particular embodiment illustrated in Figure 12, power transform system
735
has a stacked configuration in which drive gears 712 and driven gears 714 are
arranged in two respective planes 708a-b. It will be appreciated that this
embodiment is presented by way of illustration only, and not limitation, and
that
other arrangements are possible and contemplated. For instance, in some
embodiments, drive gears 712 and driven gears 714 may be stacked so as to have
1o drive gears 712 and driven gears 714 aligned in three, four, five or more
planes, as
desirable or suitable for a particular application.
A stacked arrangement can be particularly beneficial for a variety of
different
applications. For instance, in a retrofit application, a transmission may be
required
to fit within a particular envelope. In some cases, the envelope may allow the
transmission to have a relatively long axial length while allowing for only a
limited
width. In such a case, additional stacks of drive and driven gears can add to
the
length of the transmission, which may easily fit within the length of the
available
footprint, while the width requirement can easily be satisfied.
As also disclosed herein, it can be desirable for some applications to
increase the
frequency of dead-center engagement between drive gears 712 and driven gears
714. As noted previously, one manner for increasing such engagement is to use
a
Vernier relationship.. As reflected in Table 1, not all Vernier relationships
are equal,
and engagement frequency can be further increased by further varying the
number
of drive and driven gears. For instance, one of four drive gears which
alternately
engage three driven gears will encounter dead center engagement every thirty
degrees along an orbital path. This engagement can be increased, however, by
increasing the number of drive and/or driven gears. Further still, one of four
drive
gears will directly engage one of five driven gears every eighteen degrees.
Better
still, one of nine drive gears will directly engage one of eight driven gears
every five
3o degrees.
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As the number of gears increases, possibly while maintaining a Vernier
relationship, size and performance characteristics of the transmission can be
affected. For example, consider a simple example in which it has been
determined
that to obtain the desired performance, the transmission can utilize four
driving
gears that are each two inches in diameter. Additionally, to fit the width
constraints
and obtain a desired range of gear ratios, the diameter of the orbital path
should be
varied between four-and-a-half inches and ten inches.
In a single plane embodiment with driving gears which are located within the
interior of driven gears, it will be appreciated that four driving gears may
be unable
io to operate at the smaller end of the desired orbital paths. For instance,
when the
driving gears translate inward, thereby defining a virtual gear and orbital
path each
having a diameter of about five inches, the four driving gears within the
interior of
the orbital path begin to collide. The driving gears begin to engage against
each
other, thereby interfering with each other's motions. Consequently, the
transmission may not be able utilize the driving gears at orbital paths
between four
and a half and five inches in diameter. Consequently, the transmission may be
unable to provide the desired range of gear ratios.
One possible solution to this problem involves decreasing the number of
driving
gears or using smaller driving gears, thereby increasing the space available
within
the inside of the orbital path. Each alternative solution may be useful and
viable in
some applications. However, as noted previously, reducing the number of
driving
gears may affect the frequency of dead center engagement, while reducing the
size
of the driving gears may make them more prone to failure when transferring
torque.
Accordingly, in some applications, other solutions may be required. Another
possible solution is to adjust the drive train so that the driving gears can
provide the
desired gear ratio at larger orbital paths. While also possible, this
alternative can
require an increase to the size of the transmission, and may not be suitable
for
some applications.
The embodiment illustrated in Figure 12 illustrates another alternative
solution
which takes account of such situations. For example, as shown in the
illustrated
embodiment, power transport system 735 can use four drive gears 712 of the
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CA 02736815 2011-04-14
desired size, even where the diameter of the orbital path is decreased. This
is
implemented by separating drive gears 712 into multiple stacks. In the
illustrated
embodiment, for example, drive gears 712 are separated into two stacks.
Specifically, two of drive gears 712a-b reside in a first plane 708a, while
the
remaining two drive gears 712c-d are axially offset from each other and reside
within a second plane 708b.
In the first plane 708a, drive gears 712a are spaced around a circle. In the
illustrated embodiment, drive gears 712a are separated from each other at one-
hundred eighty degree intervals. Additionally, drive gears 712b are similarly
io spaced in second plane 708b. In the illustrated embodiment, the sets of
drive
gears 712 are rotated relative to each other. In particular, drive gears 712c-
d are
rotated ninety degrees with respect to drive gears 712a-b. As a result, and as
illustrated in Figure 12, the four drive gears 712 are spaced around a circle
and
separated from each other at ninety degree intervals, such that there are four
angular locations for drive gears 712.
To maintain engagement between drive gears 712 and driven gears 714, driven
gears 714 can also be placed in a stacked configuration. In the illustrated
embodiment, for instance, five driven gears are aligned in each of the first
plane
708a and the second plane 708b for engagement with drive gears 712, such that
the five driven gears 714a of the first plane 708a can be axially offset from
the five
driven gears 714b of the second plane 708b.
As further illustrated, in some embodiments of a dual stack or multi-stack
transmission, the driven gears 714 in each stack may be aligned along common
axes. For instance, each of the five driven gears 714 in each plane 708a-b can
be
spaced about a circle at seventy-two degree intervals. The driven gears 714 of
each stack may also be rotated relative to the driven gears of the other one
or more
stacks. In other embodiments, however, the driven gears 714 of one or more
stacks may not be rotated relative to each other stack. In the embodiment
illustrated in Figure 12, for instance, each of the five driven gears 714a in
the first
plane 708a is coaxially aligned with a mating driven gear 714b of the second
plane
708b. Thus, in such an embodiment, there may be only five angular locations
for
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CA 02736815 2011-12-22
the ten driven gears 714.
As will be appreciated in view of the disclosure herein, due to the use of the
dual
stacks of drive gears 712 and driven gears 714, the diameter of the orbital
path of
drive gears 712, as well as the diameter of the virtual gear defined by the
interior
perimeter of driven gears 714, can be decreased, thereby allowing a
transmission
to have reduced width or diameter. Specifically, inasmuch as fewer driven
gears
are in each plane, crowding, interference, and raking of drive gears 712
within the
orbital path is reduced or eliminated, thereby allowing more driving gears 712
to be
placed within the same area when compared with a single plane transmission.
io Furthermore, the illustrated embodiment maintains a Vernier relationship
between
drive gears 712 and driven gears 714. Specifically, the illustrated embodiment
utilizes four driving gears and ten driven gears, for a four-to-ten ratio.
However,
because the driven gears 714 are coaxial in each plane, such that there are
only
five angular locations for driven gears 714, the Vernier relationship between
the
driving and driven gears can also be expressed as a four-to-five ratio, and
dead
center engagement will occur between one drive gear 712 and one driven gear
714
every eighteen degrees.
As will be appreciated, the rotations and orbits of drive gears 712a and 712b
can
be linked together, as can the rotations of driven gears 714a and 714b. Such
linkages can be maintained in any suitable manner, including those disclosed
herein, particularly with reference to Figures 1A-B and 11A-B. In some
embodiments, the drive gears 712 in each plane can therefore rotate and orbit
in
the same direction. For instance, by way of example only, drive gears 712 in
each
plane can rotate in a clockwise direction and orbit in a counterclockwise
direction.
Accordingly, drive gears 712 may therefore also cause driven gears 714 to
rotate in
the same direction, e.g., counterclockwise, in both planes 708a-b.
Accordingly, both the magnitude and direction of the orbital and rotational
motions
of drive gears 712, and the magnitude and direction of the rotational motions
of
driven gears 714, can be constant, irrespective of the plane in which a drive
gear
712 or driven gear 714 is located. It will be appreciated, however, that this
is
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CA 02736815 2011-12-22
exemplary only. In other embodiments, for instance, drive gears 712a may
rotate
and orbit in a direction opposite that of drive gears 712b, and driven gears
714a
may rotate in a direction opposite that of driven gears 714b. For instance, a
differential may connect the drive and driven gears in each plane, thereby
causing
the drive gears and driven gears in one plane to have an equal but opposite
motion
relative to the drive gears and driven gears located in a second plane.
Specifically,
drive gears 712 in each of planes 708a-b may have rotational and orbital
motions
of the same size and magnitude, but in opposite directions. Similarly, driven
gears
714 in each plane may therefore also have rotational motions which are of
equal
magnitude but opposite in direction.
It should be appreciated in view of the disclosure herein that the embodiment
illustrated in Figure 12 is exemplary only and that any of a variety of
different
numbers of planes, stacks, or gears may be implemented according to the
present
invention. Additionally, in some embodiments it may not be necessary to use
drive
gears 712 which rotate. In particular, according to one embodiment, drive
gears
712 may be fixed such that they orbit but do not rotate. As a result, the
velocity
transferred to driven gears 714 is a function of only the orbital motion of
drive gears
712 and not a function of both orbital and rotational motions. Moreover,
inasmuch
as it is not necessary that drive gears 712 rotate, they may also be replaced
by
other driving members. For instance, according to one embodiment, drive gears
712 may be replaced with driving forks which do not rotate. In particular, a
driving
fork may have teeth only on the outer perimeter where the driving fork will
engage
driven gear 714, thereby causing driven gear 714 to rotate.
Accordingly, a transmission according to the principles of the present
invention can
be adapted for use in any of a variety of applications, and the present
invention is
not limited to any particular configuration or application. For example, a
constant
engagement, variable speed transmission according to the present invention can
be used in motor vehicles, in other applications using variable speed
transmissions,
or even in still other applications which have previously not taken advantage
of
variable speed transmissions.
Figure 13 provides a schematic illustration of one manner in which a
transmission
CA 02736815 2011-04-14
according to the present invention can be implemented. In particular, in the
illustrated embodiment, a transmission 700 is disposed between a power source
702 and a load 704. In this manner, transmission 700 is configured to transfer
the
power provided by power source 702 to drive load 704. Moreover, where
transmission 700 is a variable speed transmission according to example
embodiments of the present invention, it can provide a large, and possibly
infinite,
number of gear ratios over a range of gear ratios and/or provide an engaged
neutral for load 704.
In addition, and as further illustrated in Figure 13, a drive train may be
used to
io operably connect power source 702 to load 704 through transmission 700. As
illustrated, for example, an exemplary drive train includes a first drive
member 701
which operably connects power source 702 to transmission 700. In one
embodiment, for example, drive member 701 may be a rotary input shaft which
transfers torque output from power source 702 to an input interface of
transmission
700. In some embodiments, the torque input shaft is a single shaft directly
connecting power source 702 to transmission 700 although it should be
appreciated, particularly in light of the disclosure herein, that in other
embodiments
drive member 701 may also include more than one interconnected shaft, gears,
belts, chains, or other members which transfer power between power source 702
and transmission 700.
Additionally, as noted herein, transmission 700 may receive the power or
torque
provided by power source 702 and provide a variable speed output. For example,
where power source 702 is connected to transmission 700 by one or more torque
input shafts, power source 702 may provide a power supply to transmission 700,
and transmission 700 then changes the speed of the input to provide any of a
variety of output speeds and/or output directions. As disclosed herein,
transmission 700 may be a variable speed transmission which provides, over a
range of gear ratios, a large, and possibly infinite, number of gear ratios
for
providing different output speeds. Moreover, transmission 700 may, in some
3o embodiments, be configured to change between a forward and reverse output.
In
some embodiments, a change between a forward and reverse output can be made
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without substantial disengagement of power source 702 from load 704 and/or
without substantial disengagement between one or more sets of drive and driven
gears in transmission 700. Further, in some embodiments, transmission 700
further defines a neutral output state where no, or negligible, power is
output by
transmission 700. In one embodiment, however, the neutral output state is
preserved by nevertheless substantially maintaining a connection between power
source 702 and load 704 by, for example, maintaining an engaged neutral in
transmission 700.
As power is output from transmission 700, the power may then be transferred to
1o the load by at least one second drive member 703. Drive member 703 may be,
for
example, an output shaft which rotates as transmission 700 provides the
output. It
will be appreciated that as drive member 703 receives output torque, a torque
flow
path is defined between the torque input into transmission 700 and the torque
output of transmission 700.
In some embodiments, transmission 700 includes a single transmission or
multiple
transmissions. For example, it is contemplated that a single transmission be
used
to provide a large range of gear ratios. In other embodiments, multiple
transmissions can be used to obtain a final gear ratio change.
In an embodiment in which multiple transmissions are stacked, each
transmission
may provide a smaller range of variable gear ratios but when combined, a
larger
range of gear ratios is possible. For example, power input into a first
transmission
can be output at a first gear ratio where it is then input into a second
transmission
where a second gear ratio is applied. As a result, the final gear ratio
between the
input to the first transmission and the output of the second transmission can
be
greater than may be provided by either transmission alone.
Accordingly, one aspect of using multiple transmissions that are stacked in
this
manner is that each transmission may be smaller than would otherwise be
necessary to obtain the final gear ratio within a single transmission. As a
result, in
an application which has a small outside diameter into which the transmission
can
3o be placed, but a greater length available, multiple transmissions can be
"stacked"
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end-to-end to provide the larger range of gear ratios. This can be
particularly
useful where a traditional transmission is removed and retrofit with a
transmission
according to the present invention. For example, where a traditional
transmission
is removed, the new transmission must fit within the envelope left by the
removed
transmission. If that transmission has a large length and a smaller width,
transmissions can be stacked to provide a range of gear ratios. It should be
appreciated, however, that it is not necessary that multiple transmissions be
stacked to obtain the range of gear ratios of a traditional transmission. In
fact, in
some embodiments of the present invention, changing the lever length by less
than
io three inches can provide a full range of gear ratios commonly used by a
traditional
transmission, and possibly many more discrete or non-discrete gear ratios
within
that range. Accordingly, a transmission according to an embodiment of the
present
invention may be constructed which fits within the envelope of a traditional
transmission and which provides the same or a greater range of gear ratios.
As disclosed herein, a transmission according to the present invention can be
implemented in any of a variety of applications. In that regard, power source
702 is
then representative of any of a variety of different power sources, used in
any of a
variety of applications, and load 704 is representative of any of a variety of
different
loads which are moved by or operated in connection with power source 702. In
one embodiment, power source 702 may be, by way of example and not limitation,
an electric and/or internal combustion engine, although any other suitable
power
source is contemplated. Such an engine may be used, for example, in a
passenger or other type of motor-powered vehicle, e.g., a passenger vehicle,
tractor/trailer, a military vehicle, marine vehicle, airplanes, helicopters,
all-terrain
vehicle, construction equipment, and the like. In any such case, load 704 can
include the vehicle itself, as well as any weight supported by or contained
within the
vehicle. For example, such a vehicle may include a plurality of wheels which
are
used to move the load. In such an embodiment, transmission 700 can be
connected to the wheels by means of a drive train, represented by drive member
701. Accordingly, power output from transmission 700 is passed from drive
member 701 to the wheels which then carry and transport the other weight in
the
vehicle, as represented by load 704.
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A particular aspect of a transmission according to the present invention is
the ability
to use the transmission in a variety of applications which have low or high
torque
requirements. For example, vehicles such as snowmobiles may have relatively
low
torque requirements which allow the snowmobile to operate with a friction-
based
CVT or IVT transmission. However, a semi tractor-trailer or any application
which
has a large associated load will have a larger torque requirement that makes
such
a transmission impractical. A transmission according to the present invention,
however, because it does not rely on friction, is not prone to the burn-ups or
frictional heating problems associated with such friction based systems.
Moreover,
io because small gear ratio increments can be obtained beginning at neutral
and
extending in forward and reverse directions, a load in such an application can
be
started without feathering the clutch or otherwise creating friction that
causes burn-
ups in even steel-on-steel systems. In fact, as disclosed above, transmission
according to some embodiments of the present invention can be implemented
without a clutch or clutch plates, thereby also reducing heat generated
through
frictional clutching. Further still, because the need for such clutch plates
can be
eliminated, the hydraulic controlling systems that control the associated
clutches
can be reduced or eliminated, thereby lightening the load which must be driven
by
power source 702, and allowing a smaller, more efficient power source to be
used.
While motorized vehicles are one application in which a transmission according
to
the present invention can be used, it will be appreciated that transmission
700 can
be used in connection with a power source 702 and load 704 representative of
any
of a variety of other applications. For example, in one embodiment, power
source
702 and load 704 are representative of a conveyor system. In such an
embodiment, an electric or other motor may drive a conveyor belt which carries
raw
materials, assembled products, or any other substance or product along a
conveyor track. Accordingly, the track and conveyed substances contribute to
load
704 while the engine is represented by power source 702.
In a conveyor system embodiment as described herein, when a conveyor system
uses a transmission 700 according to embodiments of the present invention, a
substantial benefit can be seen. For example, transmission 700 may operate at
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any of a large number of gear ratios which are changeable in very small, and
possibly infinitely small, increments. Accordingly, when a conveyor system is
to be
started, a low gear ratio can be used to transfer power from power source 702
to
the conveyor belt which then starts up at a low speed. As the belt system
builds
momentum, transmission 700 can be controlled to increase the gear ratio,
thereby
changing the gear ratio. Moreover, when it is necessary to stop the conveyor
system, transmission 700 can be controlled to provide a neutral while
maintaining
power source 702 in connection with load 702. As a result, when the conveyor
is to
be started back up, power does not need to be reengaged, and transmission 700
1o can be controlled to ramp back up to operating speed. Further still, in
some
embodiments, power source 702 can operate at a constant speed and transmission
700 can provide a large number of gear ratios along a slideable or steppable
range
of ratios. As a result, a single engine used to operate over multiple speeds
can be
produced which is smaller than conventional systems, thereby also increasing
the
efficiency of the system.
In another aspect, transmission 700 can be used in an elevator, ski lift,
gondola, or
other people-mover system. For example, in such an embodiment, transmission
700 may be connected to an electric engine, combustion engine, or some other
type of engine which acts as a power source 702 to drive the load 704, which
can
include the elevator carriage, lift chairs, gondolas, the people and equipment
being
transported, and the like. In such applications, variable speed transmissions
have
typically not been used as it presents a safety concern to disconnect the
power
source from the load which carries the people. However, if a transmission
according to the present invention is used, it will be appreciated that
transmission
700 can provide a constant connection between the load and the power source,
while also providing for a variety of gear ratios. Moreover, in such a system,
as the
load increases, instead of requiring more power out of the engine,
transmission 700
can be controlled to change the gear ratio, thereby allowing the same, smaller
engine to move a larger load.
In yet another aspect, a transmission 700 according to the present invention
can be
implemented in a power generation system. For example, in one embodiment,
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power source 702 includes or is obtained from a wind or hydraulic power
source.
Accordingly, and by way of example only, transmission 700 may be employed in a
windmill application or in a hydroelectric dam. For example, wind and moving
water possess kinetic energy which can be captured by turbine blades and
transferred to transmission 700 by drive member 701. For example, drive member
701 may be a shaft which is rotated as the kinetic energy of the wind or water
is
captured. In addition, drive member 701 may include the turbine blades such
that
a kinetic power source is input into drive member 701, and drive member 701
then
converts it to a rotary power source for input into transmission 700.
1o As the rotating shaft inputs power into transmission 700, the supplied
torque can
flow through transmission 700 where it is output at any of a variety of speeds
and
connected by means of second drive member 703 to a generator represented by
load 704, which turns the rotational energy into electricity. Some generators
may,
however, require a threshold amount of rotational energy before power
generation
can occur. Accordingly, in such an embodiment, transmission 700 can be
employed between the generator and the turbine blades such that with very
little
wind or water flow, a larger rotational speed of drive member 703 can be
obtained.
Moreover, as the flow is increased, and more torque is being provided, the
variable
ratios of transmission 700 can be used to increase the power generation,
thereby
obtaining a greater power output of the generator. In this manner, a larger
range of
wind and water flows can be used to produce power and greater advantage can be
taken of large flows.
In still other embodiments, transmission 700 may also be employed in a human
or
animal powered system such that the human or animal provides the power and
acts as power source 702. For instance, according to one example embodiment,
transmission 700 may be implemented in a bicycle in which a human user
provides
the power input and in which the bicycle and the load on the bicycle act as
load
704. In this manner, as the human operator of the bicycle provides power to
transmission 700, through drive member 703, for example, transmission 700 can
implement any of a variety of gear ratios as necessary to provide power
transmission to load 704.
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As will be appreciated in light of the disclosure herein, one aspect of a
transmission
according to the principles of the present invention is the variety of
applications with
which the transmission may be used. Although various exemplary applications
are
described herein, it will be appreciated that a transmission of the present
invention
is not so limited. In fact, it is contemplated that a transmission according
to the
present invention may be used in any application in which a variable speed
transmission is desirable, regardless of whether such an application currently
uses
a variable speed transmission. Moreover, the type of power source usable with
a
transmission according to the present invention is not limited to any
particular type
of power source. For instance, as disclosed previously, the power source may
be
an engine, a human operator, or a natural source, or any combination of these
or
any other type of power source.
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