Note: Descriptions are shown in the official language in which they were submitted.
2~67103
Title: No-Slip Continuously Variable Tr~n~mission
Inventor: Noru Gogovitza
FIELD OF THE T~VE~TION
This invention relates to rotational coupling devices and more
particularly to trAn~miSsions having drive ratios continuously variable
10 between predetermined minimum and maximum amounts.
BACKGROUNl:~
Many devices for providing rotational force such as internal
15 combustion ~ngines and electrical motors operate most efficiently over a
range of rotational speeds (usually measured in revolutions per minute or
"r.p.m.") that is relatively narrow. Many applications for such devices
however require both rotational speeds outside of the range and
incr~mentAl variations of speed.
Previously rotational speeds in applications for such devices have
been controlled by controlling the speed of the device, interspersing a
variable ratio tr~ns-mi~sion between the device and a driven component or
combinations of both.
A common example is an automobile where speed is controlled both
by varying the speed of the engine and using a tr~n~mi~sion or gear box in
which various "drive ratios" can be selected. The "drive ratio" is
determined by the number of revolutions of an input shaft into the
30 tr~nsmission required to cause one revolution of the output shaft.
The two most common automotive trAn~miCsions are manually
selected trAn~mi~sions and automatically selected tr~nsmi~sions. More
modern manually selected trAnsmiSsions of the type referred to as
35 "syncromesh" or "constant mesh" tr~n~missions have a number of input
gears connecPble to an input shaft which transmits rotational force to a
colles~onding number of gears connectable to an output shaft through a
"cluster gear" comprising a corresponding number of gearsets cut into a
single member. Selection of ratios in a manual trAn~mi~sion is achieved by
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locking selecte~1 gears to the input and output shafts, the rem~ining gears
being free to rotate without transmitting rotational force.
Most modern automatic tr~An~missions use a series of planetary
5 gearsets each r~pAkle of two ratios depPn~ing on how the components of the
gearsets are constrained to move by hydraulically activated friction clutches
referred to as "bands".
Both manual and automatic tra~mi~sions are quite complex and
10 expensive because of the requisite number of accurately machined and fitted
components.
Despite advances made in automotive trAn~ Ssions~ they are
generally limited to anywhere from three to five ratios by space and cost
15 considerations usually requiring a combination of engine speed and gear
selection to adequately control the speed and power requirements of the
automobile. This results both in automobile en~ines often being operated
out of their optimal r.p.m. range and an lm(1esirable jerk resulting from the
interruption and resumption of rotational coupling between the input and
20 output shafts required to change from one combination of gearsets to
another.
Various attempts have been made in the past to provide
trAnsrnissions wherein the drive ratio is continuously and non-
25 incrPmentAlly varied without requiring coupling and decoupling of variousgearsets. Many of these attempts have been based on a design first built by
Messrs. Daimler and Benz in 1886.
The Daimler-Benz continuously variable tr~n~mission which is
30 illustrated as '1~ig. 1" herein ("C.V.T.") essentially used a rubber V-belt 1 riding between two opposed pairs of shallow angle cones 2. Moving each
pair of cones toward each other would cause ~e belt to ride "higher" on the
cones and in effect run on a pulley of larger diameter. Moving the cones
apart (as indicated by arrows 3) would cause the belt to run "lower" on the
35 cones and in effect run on a pulley of smaller diameter. Simultaneously
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moving one pair of cones toward each other while moving the other pair of
cones away from each other (as indicated by arrows 4) would vary the
relative drive ratios between the pairs of cones.
A problem with the Daimler-Benz design is that attempts to transmit
significAnt amounts of torque result in slippage of the belts.
The reason that many C.V.T. designs rely on the Daimler-Benz
principle is that the V-belt frictionally engages the cones thereby avoiding
any problems associated with causing toothed components to continually
mesh with each other or with a chain despite diametrical changes which
would ordinarily cause variations in the pitch of the teeth. However the
transmission of significant amounts of torque is better achieved by
components which mesh rather than by frictionally coupled components.
SUMMARY OF THE INVENTION
A continuously variable trAn.smi~sion having input and output
gearsets rotatable about generally coplanar respective axes of rotation and
bevelled faces in a spaced apart parallel relationship to define openings
therebetween;
said input and output gearsets are mounted opposite one another
with said openings Alignerl;
a restorably deformable transfer ring is mounted between said input
and output gearsets with a respective portion of said transfer ring being
captured between each said input and output gearsets;
said transfer ring is laterally moveable relative to said input and
output gearsets by lateral positioning means;
rotation of said bevelled gears of said input and output gearsets
deforms said transfer ring and causes said transfer ring to rotate about said
transfer ring axis and in turn impart rotational motion of said bevelled gears
of said output gearset about said respective axes of rotation in an amount
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determined by the relative lateral position of said transfer ring and said
input and output gearsets.
- 5 D~ PTION OF DRAWINGS
The invention is described below in more detail with rererel-ce to the
accompanying drawings in which:
Figure 1 is a perspective view of a "prior-art" C.V.T.;
Figure 2 is a perspective view of a C.V.T. according to the present
invention;
Figure 3 is a section on line 3-3 of Fig. 2;
Figure 4 is a perspective view showing the detail of a section of a
transfer ring according to the present invention; and
Figure 5 is a partial sectional view illustrating the interrelationship
between a transfer ring and a gearset according to the present invention.
Figure 6 is a perspective view of an adjustable locator movement
means;
Figure 7 is a section on line 7-7 of Figure 4; and
Figure 8 is a section on line 8-8 of Figure 4.
~çrip~inn of P~ ed Embo~liments
A C.V.T. according to the present invention is generally indicated by
refe~ ce 10 in Figs. 2 and 3. The C.V.T. 10 has an input gearset 12 to the left
of Fig. 2 and an output gearset 14 to the right of Fig. 2. The input and output
gearsets 12 and 14 respectively each include a pair of bevel gears 16.
Each of the bevel gears 16 is rotatably mounted at one end to an
adjustable locator 18 described in more detail below and at the opposite end
to a housing 20. Each of the bevel gears 16 is rotatable about a respective axisof rota~on 22.
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The bevel gears 16 are mounted with the axes of rotation 22 generally
coplanar and with toothed bevelled faces 24 parallel and spaced apart to
define a parallel-sided opening 26 between adjacent portions of the faces 24.
The openings 26 are aligned to engage opposite ends of a generally disc-
5 shaped transfer ring 28.
The pairs of bevel gears 16 in each of the input and output gearsets 12and 14 respectively are rotationally coupled by mitre gears 30 which cause
the bevel gears 14 of each gearset to rotate at equal amounts (i.e. equal
angular velocities) but in opposite directions relative to each other.
The teeth 24 of each bevel gear 16 taper loward a narrower end 32 of
the bevel gears 16. Between each of the teeth 24 are spaces 34 which
colles~ond in breadth to the teeth 24 so that the bevel gears 16 could mesh if
they were not spaced apart by the breadth of the openings 26.
The structure of the kansfer ring 28 is illustrated in detail in Fig. 4.
15 The transfer ring 28 is of generally annular configuration and comprises a
large number of adjacent segments 40 radially ~ligne~l with a transfer ring
axis 42. Each segment 40 has a generally rectangular central portion 41 from
opposite sides of which extend generally rectangular tabs 44. The segment~
40 are mounted between opposed, annular r h~nnel shaped retention rings
20 46 with each of the tabs 44 e~ct~nc3ing into opposed rh~nnpl~ 48 of the
retention rings 46. The segments 40 are individually axially moveable
parallel to the transfer ring axis 42 in the directions illustrated by arrows 50.
At spaced intervals, for example, every 30 along the circulllrerel,ce of
the transfer ring 28 are fixed segrnen~ 105 that transfer force from the axially25 moveable segments to the annular rh~nnel shaped retention rings 46. The
fixed ~egrnents 105 are rigidly secured to the retention rings 46, for example
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by welding, and do not project above the retention rings 46. Figure 8
illustrates this configuration in more detail.
The sides of ~h~nnels 48 interact with the tabs 44 to act as first and
second stops to limit axial movement of the segments 42 to an amount
5 predetermined by the breadth of the ~h~nnel~ 48 and the height of the tabs
44.
The transfer ring 28 is mounted between a disc shaped inner transfer
ring rePining member 52 and an annular outer transfer ring ret~ining
member 54. Ball bearings 56 run in concave grooves 58 extentling around
10 the inner and outer perimeters of the retention rings 48, the outer transfer
ring ret~ining member 54 and the inner transfer ring ret~ining member 52.
The transfer ring 28 and the segments 40 are thereby constrained to rotate
about the transfer ring axis 42.
The adjustable locator 18 has a generally rectangular body e~ctPnt1ing
15 through a generally rectangular slot 60 in the inner transfer ring retAining
member 52 and is laterally moveable in the directions indicated by arrows 62
in Fig. 2. Generally rectangular restraining members 63 secured to opposite
faces 64 of the adjustable locator 18 restrain the adjustable locator 18 from
moving ~ e~ r to the inner transfer ring ret~ining member 52 in the
20 direction of the transfer ring axis 42.
Opposed faces of the rectangular slot 60 through the inner transfer
ring retention member 52 act against the faces 64 of the adjustable locator 18
to constrain the adjustable locator 18 to movement along the rectangular
slot 60. The rectangular slot 60 has a slot axis 70 extPn~ling along its length.25 The slot axis 70, the transfer ring axis 42 and the axes of rotation 22 of the
bevel gears 24 lie in the same plane.
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As the input and output gearsets 12 and 14 respectively are mounted
to the adjustable locator 18, relative lateral movement between the
adjustable locator 18 and the inner transfer ring retenhon member 52 in the
direction shown by arrows 62 will result in corresponding lateral movement
5 of the transfer ring 28 relative to the bevel gears 16 along the opening 26.
Fig. 6 illustrates one manner in which relative movement between
the adjustable locator 18 and the inner transfer ring retention member may
be achieved. The adjustable locator 18 is rigidly secured to the housing 20. A
pinion shaft 90 extends through the housing 20 and is mounted so as to be
10 constrained to rotate about a pinion shaft axis 92 generally coaxial with thepinion shaft 90. A pinion 94 is rigidly mounted to one end of the pinion
shaft 90 and rotatable with the pivot shaft 90 about the pinion axis 92.
A rack 96 is rigidly mounted to the inner transfer ring retention
member 52 adjacent to the opening 26 and generally parallel to the slot axis
15 70. The pinion 94 engages the rack 96.
The opposite end 100 of the pinion shaft 90 extends through the
housing 20 and a crank 102 extends generally radially therefrom and is
rigidly secured thereto. Rotation of the crank 102 in the direction of arrows
104 will cause a corresponding rotation of the pinion shaft 90 and
20 accordingly will rotate the pinion 94 about the pinion shaft axis 92. Rotation
of the pinion 94 will cause the rack 96 to move laterally and in turn cause
the inner transfer ring retention member 52 to move relative to the
adjustable locator 18 in the direction of arrows 62.
Other means to cause relative movement between the adjustable
25 locator 18 and the inner transfer ring retention member would no doubt be
apparent to one skilled in the art. For example a hydraulic cylinder may be
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mounted between the adjustable locator 18 and the inner transfer rigging
retention member 52.
Reference is now made to Fig. 5 which illustrates the
interrelationship between the pairs of bevel gears 16 of each of the input and
output gearsets (12 and 14 respectively in Figs. 2 and 3) and the transfer ring
segments 40. The bevel gears 26 are arranged so that as they rotate relative to
each other in the directions shown by arrows 70, each of the teeth 24 of one
of the pairs of bevel gears 16 lines up in turn with one of the spaces 34
between the teeth 24 of the opposite bevel gear. In other words the adjacent
bevel gears 16 would mesh were it not for the openings 26 resulting from
the parallel spaced apart relationship of each pair of bevel gears 16.
The gap between a tip 72 of a tooth 24 of one of the bevel gears 16 and
a base 74 of the colle~ponding space 34 of the opposite of the bevel gears 16
generally accords with the height of the rectangular central portion 42 of the
segments 42. The depth of the spaces 34 (i.e. the height of the teeth 24)
should correspond to the predetermined amount of axial movement of the
segments 40. Accordingly as the pair of bevel gears 16 rotate, the teeth 24 of
one of the bevel gears 16 will axially displace certain of the segments 40 in
the direction indicated by arrows 50 into the opposed space 34 thereby
causing the portion of the transfer ring 28 trapped there between to conform
to the shape of the space defined between adjacent portions of the bevel
gears 16. In a sense therefore the bevel gears 26 form temporary "teeth" in
the transfer ring 28 as the transfer ring 28 passes between them thereby
effecting a me~ h~ni- ~l rather than a friction~l transfer of force.
It will be appreciated therefore that rotation of the input gears 12
about the axes of rotation 22 will cause the transfer ring 28 to rotate about
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the transfer ring axis 42 and in turn cause rotation of the output gearset
about respective axes of rotation 22.
As the input and output gearsets 12 and 14 respectively include bevel
gears 16, the amount of movement imparted by the input gearset 12 on the
5 output gearset 14 will be dele, ..~ e-l by the position of the input and output
gearsets, 12 and 14 respectively, and the transfer ring 28.
As illustrated in Fig. 2, the transfer ring 28 runs between the narrower
end 32 of the bevel gears 16 of the input gearset 12 and the broader end of the
bevel gears 16 of the output gearset 14. This results in a gear reduction and
10 eolle~onding torque multiplication. If the input and output gearsets 12 and
14 were moved to the right as illustrated in Fig. 2 by moving the adjustable
locator 18 to the right relative to the transfer ring 28, the amount of
reduction would ~iiminish and as the extreme right is approached would
result in a torque reduction and corresponding angular velocity
15 multiplication.
Various means of transferring rotational motion into the input
gearset 12 and out of the output gearset 14 may be used. The method
illustrated in Pig. 2 uses an input shaft 80 connected to and coaxial with one
of the bevel gears 16 of the input gearset. An output shaft 82 is connecte~3 to
20 the coaxial with one of the bevel gears 16 of the output gearset 14.
The input shaft 80 and output shaft 82 are constrained to rotate about
their respective axes of rotation 22 by bearings 84 in the housing 20 and
bearings 86 in the adjustable locator 18.
The rem~ining bevel gears 16 are mounted on shafts 88 extending
25 between the adjustable locator 18 and the housing 20. Bearings 90 located the
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bevel gears 16 on the shafts 88 and constrain the bevel gears 16 to rotate
about their respective axes of rotation 22.
As mentioned above, the teeth 24 and spaces 34 of the bevel gears 16
are tapered in that they narrow toward the nallower end of the bevel gears
5 16. Accorlil,gly the number of segrn~nt~ 40 of the transfer ring 28 trapped inthe space between opposed teeth 24 would vary depPn-ling on the breadth of
the portion of the teeth 24 and spaces 34 adjacent to the trapped segments 40.
In order for the se~nents 40 to lie with adjacent faces abutting the
segnlent~ 40 taper inwardly when viewed from above toward the transfer
10 ring axis 42. The tapering of the segnlent~ 40 enables the tangential load
imparted by the input and output gearsets 12 and 14 respectively to be spread
over the entire adjacent faces of the segments 40 thereby maximizing the
robll~tness of the unit and miniTni7.ing wear.
The above description is intencle-l in an illustrative rather than a
15 restrictive sense. Variations to the specific structure described may be
apparent to a~ropliately skilled persons while remaining within the spirit
and scope of the invention as ~lefine~1 by the claims set out below.
