Note: Descriptions are shown in the official language in which they were submitted.
CA 02519699 2000-04-03
Pedal-Vehicle Clutch And Drive System
The invention relates to a drive system and a clutch for a pedal-driven
vehicle.
The invention also relates to a method of transmitting power using a freewheel
clutch which is shiftable in two rotational directions. This application is
divided
from Canadian Patent Application 2,303,686, filed April 3, 2000.
Freewheel clutches or freewheels are known in bicycle engineering. Austrian
application AT-194253, for instance, discloses a freewheel and gear hub having
a back-pedal brake for bicycles, wherein ratchets operate without any noise.
These ratchets are controlled by a friction sleeve which frictionally slides
in the
sleeve or in an annular member which is fixedly connected to the hub sleeve.
The friction sleeve includes recesses for the ratchets, noses for limiting the
rotation, and frictional slide springs which rest on the annular member.
Furthermore, U.S. Patent 2;181,665 shows a simple construction of a freewheel
acting in one direction. In this design, a spring-biased ratchet engages in
recesses which are provided for the ratchet upon rotation of the hub in one
direction. However, it does not engage in the recesses upon rotation in the
other
rotational direction.
Furthermore, German Application DE-33 26 420 shows a freewheel clutch which
utilizes a driving clutch, half of which includes two axially-offset
eccentrics.
However, the freewheel clutch is intended only for transmitting a rotational
movement from a drive element to a driven element in one direction of
rotation.
Independent free rotational movement of the driven element is ensured in the
same direction of rotation when the speed thereof exceeds that of the drive
element.
Despite the great number of solutions offered in the field of bicycles or
similar
devices, there continues to exist a need for a freewheel clutch which can be
utilized, in particular, in pedal vehicles for children such as tricycles or
Kettcars~,
CA 02519699 2000-04-03
2
which allow pedaling in both the forward direction and the rearward direction
from an initial inoperative position. Such a design should easily permit both
a
forward movement and a rearward movement, respectively, of the vehicle.
Furthermore, there is also a need for a freewheeling design which acts in both
directions and prevents the pedals from rotating, for instance, during travel
on a
sloping terrain or while the vehicle is being pushed. Moreover, since a pedal
drive acts in both directions, the freewheel must also be operative in both
directions for reasons of safety. Accordingly, such a design may make these
devices safer by preventing a user from injuring their legs or feet on the
pedals.
The present invention provides for a freewheel clutch of simple construction
and
relatively low manufacturing costs, which is shiftable in both rotational
directions
and includes a freewheel condition which acts in both rotational directions.
According to the invention, there is provided a freewheel clutch which is
shiftable
in both rotational directions, e.g., forwards or backwards, clockwise or
counterclockwise, etc., and which includes a double-acting freewheel. The
clutch
includes a driver or catch which is fixedly andlor securely connected to a
drive
shaft, and further includes an engagement mechanism which is arranged
between the drive shaft and a driven shaft.
Additionally, the freewheel clutch utilizes a holding element which engages
the
engagement mechanism and which is frictionally engaged with or frictionally
coupled to a fixed member which may be a vehicle frame. A spring element is
utilized in the clutch such that in the inoperative state of the drive shaft,
the
engagement mechanism is maintained out of engagement with the driven shaft.
However, in the driven state of the drive shaft, the engagement mechanism is
placed into engagement with the driven shaft via the catch.
Prior to engagement of the engagement mechanism with the driven shaft, the
engagement mechanism is engaged by the holding element in a non-rotating or
stationary state, while the drive shaft and the catch are rotating due to
pedaling.
A frictional force, which is maintained between the holding element and the
fixed
CA 02519699 2000-04-03
3
member, is designed to be greater than a resilient force which is exerted by
the
spring element. This design permits the engagement of the engagement
mechanism with the driven shaft when the drive shaft is rotated a
predetermined
amount. Furthermore, the clutch utilizes an engagement force created between
the engagement mechanism and the driven shaft, which is greater than the
frictional force between the holding element and the fixed member.
Accordingly,
as a result of this design, a power transmission from the drive shaft to the
driven
shaft via the catch and the engagement mechanism is thereby made possible.
Thus, according to the invention, it is possible to drive the drive shaft
forwardly or
rearwardly (i.e., clockwise or counterclockwise) by pedaling a pedal vehicle.
Moreover, this design easily achieves a forwardly-directed movement or a
rearwardly-directed movement of the vehicle, depending on the respective drive
direction of the drive shaft and/or pedals. Thus, the freewheel clutch
according to
the invention can be shifted into both rotational directions based upon
movement
of the pedals in the corresponding directions.
Furthermore, the invention provides a double-acting freewheel which makes it
possible to move the pedal vehicle forwardly or rearwardly without pedaling.
Accordingly, this design allows the pedals to remain stationary (e.g., not
caused
to be rotated) when the vehicle is pushed in either direction. Thus, when the
vehicle is pushed in a forward direction, this movement will not cause forward
corresponding movement of the pedals in the forward direction and vise versa.
It
is thus in particular possible to push pedal vehicles with children thereon
forwardly or rearwardly without producing any rotation of the pedals. As a
result,
the risk of injury to the child's feet or legs is thereby reduced.
Preferably, the engagement mechanism which is located between the drive shaft
and the driven shaft, is designed such that it permits a positive lock or
positive
engagement between a driving part and a driven part. This positive engagement
design ensures a reliable connection between the driving and the driven part.
However, the invention also contemplates the use of frictional engagement by
the engagement mechanism between the driving part and the driven part. Such a
CA 02519699 2000-04-03
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design allows for an even simpler construction of the freewheel clutch. Of
course,
in each of these embodiments, the frictional force between the engagement
mechanism and the driven shaft must be greater than the frictional force
between
the holding element and the fixed member.
Preferably, the driven shaft is designed as an internally splined hollow
shaft. This
allows for a compact freewheel clutch which saves space, in particular, in the
axial direction.
In order to provide for a simple construction of the freewheel clutch, the
spring
element is preferably designed as a spring washer or ring. The ring or washer
may have an entirely annular shape or may be designed as a split ring or split
washer so as to permit easy mounting and/or assembly/disassembly.
Advantageously, the engagement mechanism may be designed as a locking
spline having external teeth or toothing. This design permits a reliable
positive
teeth to teeth engagement so as to connect or couple the drive shaft to the
driven shaft.
In order to obtain a redundant engagement between the drive shaft and the
driven shaft, the engagement mechanism may include two locks or engagement
elements in which each engagement element utilizes an external spline, teeth
or
toothing.
Additionally, it is preferred that the catch be designed as a semi-annular
element
having two lateral wing sections. Utilizing this design, the semi-annular
element
part of the catch can easily be connected to the drive shaft, e.g. by
conventional
attachment techniques such as welding, bonding, fasteners, etc., or any
combination thereof.
Moreover, in order to help reduce the risk of injury, a certain amount of
motional
or rotational play should exist in the drive shaft prior to the drive shaft
being
placed into engagement with the driven shaft. The amount of play can of course
CA 02519699 2000-04-03
be varied for the particular purpose. However, it is preferred that this play
be a
total of approximately 30°. Accordingly, this design allows the pedals
to have a
motional or rotational play of approximately ~ 15° in either direction
and around
an axis running through the drive shaft. Again, this allows for a total
motional or
rotational play of the pedals of approximately 30°. Stated another way,
starting
from a central or initial position, the pedals can be moved or rotated
forwardly by
approximately 15° and rearwardly by approximately 15° without
the drive shaft
causing corresponding movement or rotation of the driven shaft.
In order to limit the movement of the catch in an axial direction, at least
one of
the engagement elements of the engagement mechanism advantageously
includes inwardly-projecting noses. Preferably, the holding element which
cooperates with the engagement mechanism is designed as an annular- or ring-
like fork which has at least one engagement or projection arm. Moreover, a
fiber
friction disk or fricfiion washer is arranged as a friction-producing element
between the annular fork and the fixed member. This design permits an axially
compact construction. Moreover, the fiber friction washer is designed such
that it
can easily be replaced in case of wear.
The invention therefore provides for a freewheel clutch which is shiftable in
two
rotational directions; the clutch including a drive shaft which can rotate in
each of
two directions, a catch element which is fixedly secured to the drive shaft, a
driven shaft, an engagement mechanism arranged between the drive shaft and
the driven shaft, a fixed member, a holding element frictionally engaging the
fixed
member, and a spring element biased to release the engagement mechanism
from engagement with the driven shaft. The clutch may be a double-acting
freewheel clutch. The frictional force produced by the frictional engagement
between the fixed member and the holding element may be greater than a
resilient force which prevents the engagement mechanism from engaging the
driven shaft. The force of engagement between the engagement mechanism
and the driven shaft may be greater than a frictional force produced by the
frictional engagement between the fixed member and the holding element. The
spring element may bias the engagement mechanism towards an axis of the
CA 02519699 2000-04-03
6
drive shaft. The engagement mechanism may comprise at least two engagement
elements, and the spring element may bias the at least two engagement
elements towards an axis of the drive shaft. The engagement mechanism may
comprise a friction-engaging surface for frictionally engaging the driven
shaft; the
friction-engaging surface comprising at least one tooth or a plurality of
teeth. The
driven shaft may comprise a friction-engaging surface having at least one
tooth,
and the at least one tooth may be adapted to engage the at least one tooth of
the
engagement mechanism. Rotation of the drive shaft may cause corresponding
rotation of the driven shaft when the at least one tooth of the engagement
mechanism engages the at least one tooth of the driven shaft.
The driven shaft may comprise a hollow shaft having a plurality of internal
splines
and a plurality of internal teeth. The spring element may comprise one of a
spring
washer and a spring ring. The engagement mechanism may comprise one of an
external spline and a plurality of external teeth for engaging the driven
shaft, or
the engagement mechanism may comprise at least two engagement elements,
each of the at least two engagement elements having one of an external spline
and a plurality of external teeth for engaging the driven shaft. The catch
element
may comprise a semi-annular section having two lateral wing sections
projecting
therefrom, and may be fixedly secured to an exterior surface of the drive
shaft.
The semi-annular section may be fixedly secured to an exterior surface of the
drive shaft by welding or bonding.
The drive shaft may be adapted to rotate approximately 15° in a
clockwise
direction before the engagement mechanism engages the driven shaft or rotate
approximately 15° in a counterclockwise direction before the engagement
mechanism engages the driven shaft. The drive shaft may be adapted to rotate
approximately 15° in each of a clockwise and a counterclockwise
direction before
the engagement mechanism engages the driven shaft. The engagement
mechanism may comprise at least one engagement element, the at least one
engagement element including at least one projecting portion which can
comprise a stop for preventing the catch element from moving in the axial
direction. The fixed member may comprise a sleeve which comprises an annular
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7
shoulder which frictionally engages the holding element. The sleeve may
comprise an opening for receiving the drive shaft
The holding element may comprise an annular fork. The annular fork may
comprise a washer portion and at least one arm projecting from the washer
section. The at least one arm may be adapted to engage at least one slot in
the
engagement mechanism, or the at least one arm may comprise at least two
arms, each of the at least two arms being adapted to engage a corresponding
slot in the engagement mechanism.
The clutch may further comprise a friction washer arranged between the holding
element and the fixed member. The friction washer may be arranged between
the holding element and an annular shoulder of the fixed member. The friction
washer may comprise one of a fiber washer and a fiber-lined washer. The clutch
may further comprise one of a spring washer and a corrugated washer arranged
against the holding member. The clutch may further comprise a cover for
enclosing the engagement mechanism. The clutch may further comprise a
securing disk for securing the cover to the fixed member.
The invention also provides for a freewheel clutch which is shiftable in two
rotational directions; the clutch including a first shaft which can rotate in
each of
two directions, a second shaft comprising a hollow space, an opening for
receiving the first shaft and an internal friction surface, an engagement
mechanism arranged within the hollow shape, the engagement mechanism
comprising an exterior friction surtace, a catch element fixedly secured to
the
drive shaft, a fixed member comprising an opening for receiving the first
shaft
and an annular shoulder, a holding element for frictionally engaging the
annular
shoulder of the fixed member, and a spring element for biasing the engagement
mechanism towards the first shaft so as to prevent the external friction
surface of
the engagement mechanism from engaging the internal friction surface of the
second shaft, whereby rotation of the first shaft in at least one direction
causes a
corresponding rotation of the second shaft.
CA 02519699 2000-04-03
The clutch may be a double-acting freewheel clutch. The force of engagement
between the engagement mechanism and the second shaft may be greater than
a frictional force produced by the frictional engagement between the fixed
member and the holding element. The frictional force produced by the
frictional
engagement between the fixed member and the holding element may be greater
than a resilient force which prevents the engagement mechanism from engaging
the second shaft. The engagement mechanism may comprise at least two
engagement elements. The external friction surface may comprise at least one
tooth. The internal friction surface may comprise one of an internal spline
and a
plurality of teeth. The at least one tooth of the engagement mechanism may be
adapted to engage one of the internal spline and the plurality of teeth.
Rotation of
the first shaft may cause corresponding rotation of the second shaft when the
at
least one tooth of the engagement mechanism engages one of the internal spline
and the plurality of teeth of the second shaft.
The spring element may comprise one of a split-spring washer and a split-
spring
ring. The engagement mechanism may comprise at least two engagement
elements; each of the at least two engagement elements comprising the external
friction surface, the external friction surface further comprising one of an
external
spline and a plurality of external teeth for engaging a corresponding spline
or
teeth disposed on the internal friction surface of the second shaft. The catch
element may comprise a semi-annular section having two lateral wing sections
projecting therefrom. The semi-annular section may be fixedly secured to an
exterior surface of the first shaft by welding or bonding. The first shaft may
be
adapted to rotate approximately 15° in a clockwise direction before the
engagement mechanism engages the second shaft. The first shaft may be
adapted to rotate approximately 15° in a counterclockwise direction
before the
engagement mechanism engages the second shaft. The first shaft may be
adapted to rotate approximately 15° in each of a clockwise and a
counterclockwise direction before the engagement mechanism engages the
second shaft. The engagement mechanism may comprise at least one
engagement element, the at least one engagement element including at least
one projecting portion.
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The holding element may comprise an annular fork, the annular fork comprising
a washer portion and at least one arm projecting from the washer section. The
at
least one arm may be adapted to engage at least one slot in the engagement
mechanism.
The clutch may further comprise a friction washer arranged between the holding
element and the annular shoulder of the fixed member. The friction washer may
comprise one of a fiber washer and a fiber-lined washier. The clutch may
further
comprise one of a spring washer and a corrugated washer arranged against the
holding member. The clutch may further comprise a cover for enclosing the
engagement mechanism. The clutch may further comprise a securing disk for
securing the cover to the fixed member. The clutch may further comprise a
friction washer arranged between the holding element and the annular shoulder
of the fixed member; the friction washer comprising one of a fiber washer and
a
fiber lined washer, one of a spring washer and a corrugated washer arranged
against the holding member, a cover for enclosing the engagement mechanism,
and a securing disk for securing the cover to the fixed member.
The invention also provides for a method of transmitting power from a drive
shaft
to a driven shaft utilizing a freewheel clutch which is shiftable in two
rotational
directions wherein the drive shaft is rotatable in each of two directions; the
clutch
including a catch element which is fixedly secured to the drive shaft, an
engagement mechanism arranged between the drive shaft and the driven shaft,
a fixed member, a holding element fractionally engaging the fixed member, and
a
spring element biased to release the engagement mechanism from engagement
with the driven shaft. The method comprises rotating the drive shaft from a
freewheel position in one of a clockwise and a counterclockwise direction,
whereby the engagement mechanism is moved into an engagement position so
as to rotate the driven shaft, and returning the drive shaft to the freewheel
position. The drive shaft may be rotatable in each of the clockwise and
counterclockwise direction. The driven shaft also may be freely rotating in
one of
the clockwise and the counterclockwise direction prior to rotation of the
drive
shaft.
CA 02519699 2000-04-03
The invention also provides a clutch for a pedal vehicle having pedals and a
frame wherein the clutch is shiftable in two rotational directions; the clutch
comprising a drive shaft which can rotate in each of two directions upon
corresponding rotation of the pedals in each of the two directions, a catch
element which is fixedly secured to the drive shaft, a driven shaft, an
engagement mechanism arranged between the drive shaft and the driven shaft,
a fixed member, a holding element frictionally engaging the fixed member, and
a
spring element biased to release the engagement mechanism from engagement
with the driven shaft. The clutch allows the pedal vehicle to be moved in each
of
the two directions with or without corresponding movement of the pedals.
The invention further provides for a clutch for a pedal vehicle having pedals
and
a frame wherein the clutch is shiftable in two rotational directions; the
clutch
comprising a first shaft which can rotate in two opposite directions upon
corresponding rotation of the pedals in each of the two opposite directions, a
second shaft comprising an opening for receiving the first shaft and an
internal
engaging surface, an engagement mechanism comprising an external engaging
surface, a catch element secured to the first shaft, a fixed member comprising
an
opening for receiving the first shaft and an annular shoulder, a holding
element
for frictionally engaging the annular shoulder of the fixed member, and a
spring
element for preventing biasing the engagement mechanism towards the first
shaft. Rotation of the pedals in one direction causes a corresponding rotation
of
the second shaft, and rotation of the pedals in an opposite direction causes a
corresponding rotation of the second shaft.
The clutch may allow the pedal vehicle to be moved in each of the two
directions
with or without corresponding movement of the pedals. The clutch may allow the
pedal vehicle to be moved in each of the two directions with and without
corresponding movement of the pedals.
The invention also provides for a method of transmitting power from pedals,
which are coupled to a first shaft, to a second shaft utilizing a freewheel
clutch
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11
which is shiftable in two rotational directions, wherein the first shaft is
rotatable in
each of two directions; the clutch including a catch element which is fixedly
secured to the first shaft, an engagement mechanism arranged between the first
shaft and the second shaft, a fixed member, a holding element frictionally-
engaging the fixed member, and a spring element biased to release the
engagement mechanism from engagement with the second shaft. The method
comprises moving the pedals to cause the first shaft to rotate from a
freewheel
position in one of a clockwise and a counterclockwise direction, whereby the
engagement mechanism is moved into an engagement position so as to rotate
the second shaft, and preventing the pedals from moving and allowing the
second shaft to rotate freely in either the clockwise or counterclockwise
directions.
The preventing may comprise preventing the pedals from moving and allowing
the second shaft to rotate freely in each of the clockwise and
counterclockwise
directions. The first shaft may be rotatable in each of the clockwise and
counterclockwise direction by corresponding movement of the pedals and the
second shaft may be freely rotatable in each of the clockwise and the
counterclockwise direction prior to when the pedals are prevented from moving
the first shaft.
The invention further provides a vehicle having a clutch, pedals and a frame
wherein the clutch is shiftable in two rotational directions; the clutch
comprising a
drive shaft which is rotatable in each of two directions upon corresponding
rotation of the pedals in each of the two directions, a catch element fixedly
secured to the drive shaft, a driven shaft, an engagement mechanism arranged
between the drive shaft and the driven shaft, a fixed member, a holding
element
frictionally-engaging the fixed member, and a spring element biased to release
the engagement mechanism from engagement with the driven shaft, the clutch
allowing the pedal vehicle to be moved in each of the two directions with or
without corresponding movement of the pedals.
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In another aspect the invention contemplates a drive system for a pedal
vehicle. The
drive system comprises: a shaft that can rotate in opposite directions; an
outer member
surrounding a portion of the shaft and able to rotate in opposite directions,
the outer
member having an inner surface; and a spring surrounding the shaft and
arranged
between the inner surface and the shaft. An engaging member is movably mounted
between the portion of the shaft and the inner surface of the outer member and
has an
outer surface that frictionally engages the inner surface when the shaft is at
least
partially rotated. A mechanism moves between a first position and a second
position
when the shaft is rotated at least partially; the mechanism being arranged
between the
portion of the shaft and the inner surface of the outer member. The first
position causes
the engaging member to frictionally engage the inner surface of the outer
member, and
the second position allows the outer member to rotate relative to the shaft,
whereby the
engaging member does not frictionally engage the inner surface of the outer
member.
Alternatively, the drive system may comprise two engaging members movably
mounted
between the portion of the shaft and the inner surface of the outer member;
each of the
two engaging members comprising an outer surface that frictionally engages the
inner
surface when the shaft is rotated at least partially in at least one
direction. A mechanism
moves between a first position and a second position when the shaft is rotated
at least
partially in at least one direction; the mechanism being movable by the shaft,
being
engagable with the two engaging members, and being arranged between the
portion of
the shaft and the inner surtace of the outer member. The first position causes
engagement between the mechanism and the two engaging members such that the
outer surfaces of the two engaging members are caused to frictionally engage
the inner
surface of the outer member, and the second position allows the outer member
to rotate
relative to the shaft whereby the outer surfaces of the two engaging members
do not
frictionally engage the inner surface of the outer member.
In both drive systems rotation of the shaft in one direction causes the outer
member to
rotate in a corresponding direction, rotation of the shaft in an opposite
direction causes
the outer member to rotate in a corresponding opposite direction, and, when
the shaft is
not caused to rotate, the outer member is allowed to rotate freely in opposite
directions.
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13
The invention now will be described in further detailed description which
follows,
with reference to the accompanying drawings of embodiments, in which:
Figure 1 is a perspective exploded view of a freewheel clutch with a double-
acting freewheel according to a preferred embodiment of the invention;
Figure 2 is a sectional view of the freewheel clutch shown in Figure 1, in the
closed state of the freewheel, e.g., clockwise rotational engagement of the
engagement mechanism such that the drive shaft can drive the driven shaft in a
clockwise rotation;
Figure 3 is a sectional view corresponding to Figure 2, which shows the
freewheel clutch illustrated in Figure 1 in the opened state of the freewheel,
e.g.,
initial non-rotated state; and
Figure 4 is a partial sectional side view of the assembled freewheel clutch
shown
in Figures 1 to 3.
Figures 1 to 4 show a preferred embodiment of a freewheel clutch according to
the invention utilizing a double-acting freewheel (i.e., one acting in both
clockwise and counterclockwise rotational directions). The freewheel clutch 1
permits the transmission of power in both rotational directions, i.e.,
forwardly and
rearwardly or clockwise and counterclockwise. Freewheel clutch 1 is
particularly
suited for use in, e.g., tricycles and Kettcars~, or other devices where it is
advantageous to utilize freewheeling as well as forward and rearward shifting.
As is particularly shown in Figure 1, freewheel clutch 1 utilizes a drive
shaft 2 and
a driven shaft 4. Drive shaft 2 may be coupled to a tread or crank with pedals
(not shown), and is rotated by a force exerted on the pedals. Drive shaft 2
also
is designed to be driven in both rotational directions (i.e., clockwise and
counterclockwise) so as to permit a forward movement and rearward movement,
respectively, of the vehicle, e.g., a pedal-operated vehicle.
CA 02519699 2000-04-03
14
Freewheel clutch 1 also includes a driver or catch element or mechanism 3
which is fixedly and/or securely connected to drive shaft 2. Catch element 3
preferably includes a semi-annular section having two lateral wing sections
projecting therefrom. Each wing section also has a recess or slot 13 which
cooperates with split ring 8 as will be more clearly described below. The
connection between catch 3 and shaft 2 preferably is by way of welding or
bonding, but other conventional attachment techniques may also be employed. It
is preferred that shaft 2 and catch 3 be made of a metal, e.g., steel.
However,
other materials such as plastics and/or composites may also be utilized
provided
they contain sufficient strength to perform their function reliably.
Furthermore,
clutch 1 utilizes an engagement mechanism which may have two engagement
elements or locking elements 5, 6 and which are arranged between drive shaft 2
and driven shaft 4. Engagement elements 5, 6 preferably are designed as
locking elements such that each has an external spline or toothing 20. Again,
the
preferred material for these elements 5, 6 is a metal such as steel, but other
materials may also be utilized. Alternatively, teeth 20 may be replaced with a
friction surface or lining such as one found on some conventional centrifugal
clutches. In this regard, this surface or lining may be similar to the fiber
material
utilized in fiber washer 10 which will be described below. Nevertheless, teeth
20
are preferred over a frictional lining or surface because of their long life
and
reliability. Furthermore, freewheel clutch 1 also utilizes a split ring or
spring
washer 8 which acts as a spring element to bias locking elements 5 and 6
towards one another. Moreover, spring element 8 is received in recesses or
grooves 14 which are respectively formed on each of locking elements 5 and 6.
As shown in Figure. 1, a ring-like fork 7 is utilized which includes two
projecting
arms 17. Each projecting arm 17 is designed to project into recesses or slots
15,
16 formed on locking elements 5 and 6, respectively (see, in particular,
Figure 4).
As shown in Figure 1, locking elements 5, 6 preferably are not symmetrically
formed. Thus, in contrast to locking element 5, locking element 6 can
additionally
include two projecting noses 19, which project towards locking element 5.
Furthermore, freewheel clutch 1 also includes a sleeve 9 which may be a fixed
CA 02519699 2000-04-03
member, and a fiber disk or washer 10. Fiber washer 10 preferably is, a
compression friction washer, and is arranged between sleeve 9, more
particularly
the annular shoulder of sleeve 9, and fork 7. Sleeve 9 further may be fixedly
connected to a non-rotatable member such as the frame of the pedal vehicle
(not
shown). Freewheel clutch 1 additionally includes a corrugated washer 11 or
similar type spring and/or compression washer, a cover 12, and a securing disk
18 or similar type device which secures and/or helps retain the aforementioned
individual members on drive shaft 2 in such a manner that the members cannot
be displaced axially.
The operation of the freewheel clutch according to the invention may be
described as follows. As is especially shown in Figures 2 and 3, catch 3 is
arranged between locking elements 5 and 6. Locking elements 5, 6 are in turn
biased by spring element 8 to a predetermined extent and held around catch 3
and drive shaft 2, respectively, such that locking elements 5 and 6 are in
contact
with catch 3 (Figure 3). Accordingly, catch 3, and more particularly the wing
sections, include recesses or slots 13. Moreover, slots 13 are arranged at a
particular position on catch 3, for the purpose of receiving annular spring 8.
Additionally, the above-explained structures preferably are arranged in the
axial
direction of the rotational axis 2 inside a portion of driven shaft 4. For
this
purpose, driven shaft 4 is designed as a hollow shaft (see Figure 4). As
further
shown in Figure 4, the two arms 17 of fork 7 are designed to axially grip or
extend beyond fiber washer 10 and the annular shoulder of sleeve 9, into
recesses or slots 15 and 16, which are formed on each of locking elements 5
and
6 respectfully. Moreover, fork 7 is designed to be held or retained in an
axial
position or location by securing disk 18 via corrugated washer 11 and cover 12
(see Figure 4).
In Figure 3, freewheel clutch 1 is illustrated in a state where the freewheel
is
opened, i.e., initial non-rotated position. This means that no force is
exerted on
the pedals such that the pedal vehicle can be pushed in both directions of
travel,
i.e. forwardly and rearwardly, without causing the pedals to be rotated as a
result. When a force is then exerted on the pedals, the force will be
transmitted
CA 02519699 2000-04-03
16
via drive shaft 2 to catch 3 since catch 3 is fixed to shaft 2. Accordingly,
this
rotation force causes catch 3 to begin to rotate at the same time as drive
shaft 2.
However, since locking elements 5, 6 are directly positioned on catch 3, the
rotational force is immediately transmitted to locking elements 5, 6 such that
locking elements 5, 6 are caused to displace outwards and away from the axis
of
shaft 2. Locking elements 5, 6, however, are nevertheless prevented from
rotating yet because they are held by arms 17 of fork 7. This is because fork
7 is
prevented from rotating and thus is held stationary by reason of the friction
which
exists between fork 7; more particularly the annular shoulder of fork 7, fiber
washer 10 and fixed sleeve 9, respectively. As a result of this frictional
retention,
locking elements 5, 6 are caused to move radially or displace outwardly,
guided
by recesses 15 engaging arms 17 and against the resilient force of annular
spring 8. The resilient force for holding locking elements 5, 6 together is
accordingly designed to be smaller or less than the frictional force which is
exerted between fork 7 and fiber washer 10. Otherwise, locking elements 5, 6
could not be moved radially outwardly. Moreover, as a result of this design,
engagement elements or locking elements 5, 6, with their external toothing 20,
are positively locked or positively engaged with internal toothing 21 of
driven
hollow shaft 4.
The force generated by the positive locking or engagement is designed to be
greater than the frictional force produced by fiber washer 10 on fork 7. As a
result, this allows fork 7 to also begin to rotate together with engagement
elements 5, 6 and the drive shaft 2 and the driven shaft 4, respectively,
against
the frictional resistance on fiber washer 10. Moreover, this design permits a
positive power transmission of the force exerted on the pedals to be
transmitted
to the driven shaft 4. Such an engaged position of freewheel clutch 1 is shown
in
Figure 2. Hence, in such an engaged position, the pedal vehicle can be moved
forwardly or rearwardly by way of pedaling. Note that Figure 2 shows
engagement on one (forward or clockwise) of the two positions.
When a frictional connection (e.g., frictional engagement between teeth 20 and
teeth 21) is provided between hollow shaft 4 and engagement elements 5, 6, the
CA 02519699 2000-04-03
17
frictional force created between hollow shaft 4 and engagement elements 5, 6
must be greater than the frictional force between fork 7 and fiber washer 10,
in
order to obtain a functioning freewheel clutch.
As is apparent from Figure 2, catch 3 is in engagement via its two wing
sections
with a respective one of locking elements 5, 6, e.g., at the upper side and
bottom
side, respectively. As is clearly seen in comparison to Figure 3, catch 3 has
here
been rotated (clockwise) out of an initial position (Figure 3) along axis A--A
by
approximately 15 ° to achieve a full engagement between engagement
elements
5, 6 and driven shaft 4. However, it should be noted that if the pedals were
to be
rotated in the other direction (counterclockwise), catch 3 would be rotated
out of
the initial position A--A by 15 ° into the opposite direction (not
shown). This would
again bring engagement elements 5, 6 into engagement with internal toothing 21
of driven shaft 4 (not shown). Thus, there is an overall motional or
rotational play
of approximately 30 ° where no power is transmitted from drive shaft 2
to driven
shaft 4 such that the freewheel is opened (i.e., non-engaged) in both
directions of
trave I .
Freewheel clutch 1 according to the invention thereby ensures that, when
little or
no force is exerted on the pedals, a freewheel exists in either a forwardly-
oriented direction and a rearwardly-oriented direction, such that the pedal
vehicle
can be pushed forwardly or rearwardly without corresponding movement of the
pedals. When a force is then exerted on the pedals in a specific direction,
engagement between engagement elements 5, 6 and driven shaft 4 can
commence after a predetermined amount of rotational play (e.g. 15 ° in
either
direction for a total of approximately 30 °). As a result, the force of
the pedals can
then be transmitted to driven shaft 4. It should be noted here that the
rotational
play can be varied by adjusting the distance between engagement elements 5, 6
and driven shaft 4. Moreover, the invention is not limited to rotational plays
of 15°
andlor 30 ° However, these plays are believed to be ideal for pedal-
type devices
and are recommended.
CA 02519699 2000-04-03
18
Freewheeling clutch 1 operates equally well in either direction. Thus, when a
force is exerted on the pedals in another direction, e.g. counterclockwise,
engagement elements 5, 6 also engage into driven shaft 4 which is then rotated
in the rearward direction (not shown). Thus, the pedal vehicle can be moved
both
in the forward and rearward direction by way of pedaling.
Thus, the invention provides for a freewheel clutch 1 which is shiftable in
both
rotational directions (forwards and/or clockwise and rearwards and/or
counterclockwise) and includes a double-acting freewheel. Freewheel clutch 1
utilizes a catch 3 which is fixedly and securely connected to a drive shaft 2,
and
an engagement mechanism having engagement elements 5, 6 arranged
between drive shaft 2 and a driven shaft 4. Furthermore, a holding element 7
is
utilized which is coupled to or engaged with a fixed member 9 via frictional
resistance. Moreover, holding element 7 cooperates with engagement elements
5, 6, via recesses. Additionally, engagement elements 5, 6 are biased towards
one another and shaft 2 via a spring element 8. Spring element 8 is designed
such that when shaft 2 is in the non-rotating state, engagement elements 5, 6
are
out of engagement with driven shaft 4. Moreover, when shaft 2 is in the
driven,
i.e. in a rotating state, spring element 8 is sufficiently weak to allow
engagement
elements 5, 6 to be in engagement with driven shaft 4 via the catch 3.
It is preferred that most of the parts described herein be made of a material
such
as steel. Thus, it is preferred that shaft 2, shaft 4, elements 5 and 6, catch
3,
washers 7, 8 and 11, sleeve 9 and disk 18 all be made of a metal such as steel
since it is relatively inexpensive, strong, and relatively easy to work with.
However, cover 12 may be made from plastic or composite as well as metal.
Moreover, fiber washer 10 may be a combination of a metal washer utilizing a
fiber lining or it may be simply made of fiber or similar composite material.
Accordingly, the invention is not limited to these materials. Considerations
of
weight, cost, wear life, and reliability may require that lighter materials be
utilized
such as aluminum, plastics, and composites and/or a combination thereof.
