U.S. patent application number 12/976773 was filed with the patent office on 2011-06-23 for electronically controlled continuously variable transmission with axially movable torque transmitting mechanism.
Invention is credited to Francois Brind'Amour, Hubert Roberge, Lionel Thiebault.
Application Number | 20110152020 12/976773 |
Document ID | / |
Family ID | 44151888 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110152020 |
Kind Code |
A1 |
Brind'Amour; Francois ; et
al. |
June 23, 2011 |
ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION WITH
AXIALLY MOVABLE TORQUE TRANSMITTING MECHANISM
Abstract
An electronically controlled CVT driving pulley comprising a
pair of opposed sheaves adapted to rotate about a driving pulley
rotation axis is hereby provided, one of the sheaves including an
axial protrusion including a series of teeth cooperating with an
axial bearing mechanism providing a relative axial displacement
between the opposed sheaves and to transmit a torque between the
opposed sheaves. A kit and a method for transmitting a torque
between two opposed sheaves of an electronically controlled CVT is
also provided.
Inventors: |
Brind'Amour; Francois;
(Drummondville, CA) ; Roberge; Hubert;
(Drummondville, CA) ; Thiebault; Lionel;
(Drummondville, CA) |
Family ID: |
44151888 |
Appl. No.: |
12/976773 |
Filed: |
December 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61289857 |
Dec 23, 2009 |
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61289821 |
Dec 23, 2009 |
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61289850 |
Dec 23, 2009 |
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61289834 |
Dec 23, 2009 |
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Current U.S.
Class: |
474/8 |
Current CPC
Class: |
F16H 7/0827 20130101;
F16H 63/062 20130101; F16H 55/56 20130101 |
Class at
Publication: |
474/8 |
International
Class: |
F16H 55/56 20060101
F16H055/56 |
Claims
1. An electronically controlled CVT driving pulley comprising a
pair of opposed sheaves adapted to rotate about a driving pulley
rotation axis, one of the sheaves including an axial protrusion
including a series of teeth cooperating with an axial bearing
mechanism providing a relative axial displacement between the
opposed sheaves and to transmit a torque between the opposed
sheaves.
2. The electronically controlled CVT driving pulley of claim 1,
wherein the axial bearing mechanism further comprises a slider
member for transmitting the torque between the opposed sheaves and
guiding the axial displacement of the sheave.
3. The electronically controlled CVT driving pulley of claim 2,
wherein the slider member is axially disposed between two support
bearings.
4. The electronically controlled CVT driving pulley of claim 2,
wherein the slider member further includes a series of compression
portions and intervening junction portions, the compression
portions being adapted to reduce rotational vibrations provided by
fluctuations of the torque.
5. The electronically controlled CVT driving pulley of claim 2,
wherein the slider members includes rattle-preventing elements.
6. The electronically controlled CVT driving pulley of claim 5,
wherein the rattle-preventing elements are a series of legs adapted
to respectively contact the series of teeth.
7. The electronically controlled CVT driving pulley of claim 2,
wherein the axial bearing mechanism includes a slider member
receptacle provided with an internal series of axial teeth sized
and designed to rotatably engage the slider member.
8. The electronically controlled CVT driving pulley of claim 7,
wherein the slider member is adapted to be secured to the slider
member receptacle.
9. The electronically controlled CVT driving pulley of claim 8,
wherein the axial displacement between the sheaves is provided by a
threaded interface radially and distally disposed in respect with
the slider member receptacle.
10. The electronically controlled CVT driving pulley of claim 9,
wherein the threaded interface includes a male threaded portion and
a female threaded portion, one of the threaded portions operatively
supporting a main actuation gear axially disposed between the axial
bearing mechanism and the pair of sheaves.
11. The electronically controlled CVT driving pulley of claim 7,
wherein the slider member receptacle is rotatably secured to a
pulley.
12. The electronically controlled CVT driving pulley of claim 1,
wherein the axial protrusion is hollowed and is adapted to receive
therein an axial shaft, the axial protrusion further including at
least one bearing member intervening between the hollowed axial
protrusion and the axial shaft.
13. The electronically controlled CVT driving pulley of claim 1,
wherein the electronically assisted CVT manages the displacement
between the opposed sheaves with an electric motor and an
intervening set of gears and wherein the intervening set of gears
are substantially radially superposing the slider member.
14. A method for transmitting a torque between two opposed sheaves
of an electronically controlled CVT, the method comprising:
rotating one of the opposed sheaves; rotating a slider member
receptacle with the one of the opposed sheaves, the slider member
receptacle engaging a slider member; and transmitting the torque to
the other opposed sheave via the slider member.
15. The method for transmitting a torque of claim 14, the method
further comprising: actuating a motor to rotate a main actuation
gear; rotating a threaded body with the main actuation gear;
transforming the rotation of the threaded body into a axial
displacement thereof; and axially displacing the other opposed
sheaves with the axial displacement of the threaded body.
16. The method for transmitting a torque of claim 14, wherein the
other opposed sheave comprises a protruding end and wherein the
slider member engages the protruding end to transmit torque
thereto.
17. An electronically assisted CVT assisting mechanism adapted to
be secured in cantilever to a power drive, the assisting mechanism
comprising: a chassis; an actuation motor secured to the chassis;
and a main actuation gear operatively secured to a first threaded
portion and drivably connected to the actuation motor, the first
threaded portion being threadedly connected to a second threaded
portion to transfer a rotation of the main actuation gear to a
corresponding axial translation of an axially movable sheave, the
assisting mechanism being adapted to be polarly positioned about a
rotation axis of the axially movable sheave such that the assisting
mechanism could be secured at various angle about the rotation axis
of the axially movable sheave to be installed in a variety of
different layouts.
18. The electronically assisted CVT assisting mechanism of claim
17, further comprising a retaining member configured to polarly
secure the assisting mechanism, the retaining member preventing the
assisting mechanism to rotate or pivot about the rotation axis of
the axially movable sheave.
19. The electronically assisted CVT assisting mechanism of claim
17, wherein the retaining member is part of the chassis and is
adapted to connect a motor.
20. The electronically assisted CVT assisting mechanism of claim
17, wherein the assisting mechanism includes a slider member
therein.
Description
CROSS-REFERENCE
[0001] The present United States patent application relates to and
claims priority from U.S. provisional patent application No.
61/289,857, filed Dec. 23, 2009, entitled TORQUE LIMITING SYSTEM
AND METHOD, Unites States provisional patent application No.
61/289,821, filed Dec. 23, 2009, entitled POLAR POSITIONNABLE
CONTINUOUSLY VARIABLE TRANSMISSION, Unites States provisional
patent application No. 61/289,834, filed Dec. 23, 2009, entitled
GEAR SECURING MECHANISM, KIT AND METHOD THEREOF, and from Unites
States provisional patent application No. 61/289,850, filed Dec.
23, 2009, entitled TORQUE TRANSMITTING COUPLING, which all three
documents are incorporated herein by reference in their
entirety.
TECHNICAL FIELD
[0002] The technical field relates to electrically controlled
continuously variable transmissions. More precisely, the present
technical field relates to electrically controlled continuously
variable transmissions including a torque transmitting system
adapted to allow axial movements between continuously variable
transmissions sheaves.
BACKGROUND
[0003] Continuously variable transmissions (CVTs) are commonly used
on a wide range of vehicles, such as small cars or trucks,
snowmobiles, golf carts, scooters, all-terrain vehicles (ATV), etc.
They often comprise a driving pulley mechanically connected to a
motor, a driven pulley mechanically connected to wheels or
caterpillars, possibly through another mechanical device such as a
gearbox, a drive train and a trapezoidal drivebelt transmitting
torque between the driving pulley and the driven pulley. A CVT
changes the ratio within certain limits as required by the
operating conditions to yield a desired motor rotational speed for
a given driven pulley rotational speed, the latter being generally
proportional to the vehicle speed. A CVT may be used with all kinds
of motors, for instance internal combustion engines, electric
motors, windmills, etc. CVTs can also be used with other machines
that are not vehicles.
[0004] Each pulley of a CVT comprises two members having opposite
conical surfaces, which members are called sheaves. One sheave,
sometimes called "fixed sheave", can be rigidly connected to one
end of a supporting shaft while the other sheave, sometimes called
"movable sheave", can be free to slide and/or rotate with reference
to the fixed sheave by means of bushings or the like. The conical
surfaces of the sheaves apply an axial force on the drivebelt.
Moving the sheaves axially relative to each other changes the
drivebelt operating diameter, thus the ratio of the CVT.
[0005] In order to transmit the motor torque, an axial force has to
be applied in the driving and the driven pulleys. These axial
forces can be generated by a plurality of possible mechanisms or
arrangements. In a legacy mechanical CVT, the axial force in the
driving pulley is often generated using centrifugal weights, spring
and ramps. In a legacy driven pulley, this force is often generated
using cam surfaces and a spring.
[0006] Generally, at a low vehicle speed, the operating diameter of
the drivebelt at the driving pulley is minimal and the operating
diameter at the driven pulley is maximal. This is referred to as
the minimum ratio or the minimum ratio condition since there is the
minimum number of rotations or fraction of rotation of the driven
pulley for each full rotation of the driving pulley.
[0007] As the vehicle speed increases, so does the driven pulley
rotational speed. For a given operating condition, a certain motor
rotational speed is desired, thus a desired ratio can be
calculated. The CVT actuation mechanism is provided to set the CVT
to the appropriate ratio.
[0008] Generally, when the rotational speed of the driving pulley
increases, its movable sheave moves closer to the fixed sheave
thereof under the effect of an actuation mechanism, for instance a
centrifugal mechanism or another kind of actuation mechanism. This
constrains the drivebelt to wind on a larger diameter at the
driving pulley. The drivebelt then exerts a radial force on the
sheaves of the driven pulley in addition to the tangential driving
force by which the torque received from the motor is transmitted.
This radial force urges the movable sheave of the driven pulley
away from the fixed sheave thereof, thereby constraining the
drivebelt to wind on a smaller diameter at the driven pulley. A
return force, for instance a return force generated by a spring of
the driven pulley and/or by another biasing mechanism, often
counterbalances the radial force. It may also be counterbalanced by
a force generated by the axial reaction of the torque applied by
the drivebelt on the driven pulley, which force often results from
the presence of a cam system and/or another biasing mechanism that
tend(s) to move the movable sheave towards the fixed sheave as the
torque increases. A cam system may comprise a plurality of ramp
surfaces on which respective followers can be engaged. The
followers can be sliding buttons or rollers, for instance. The set
of ramp surfaces or the set of followers is attached to the movable
sheave. The other set is directly or indirectly attached to the
fixed sheave and is in a torque-transmitting engagement with the
main shaft supporting the driven pulley. The closing effect of the
cam system on the drivebelt tension is then somewhat proportional
to the torque received from the motor.
[0009] Generally, at the maximum vehicle speed, the ratio is
maximum as there is the maximum number of rotations or fraction of
rotation of the driven pulley for each full rotation of the driving
pulley.
[0010] When the vehicle speed decreases, the rotational speed of
the driving pulley eventually decreases as well since the
rotational speed of the motor will decrease at one point.
Ultimately, there is a decrease of the winding diameter at the
driving pulley and a decrease of the radial force exerted by the
drivebelt on the sheaves of the driven pulley. The driven pulley is
then allowed to have a larger winding diameter as the spring and/or
another biasing mechanism move(s) its movable sheave closer the
fixed sheave.
[0011] Some CVTs are provided with an integrated clutch function.
The clutch function can be on the drivebelt or be provided by a
mechanism incorporated in the CVT. For instance, when the CVT has a
clutch function on the drivebelt, the opposite walls of the fixed
sheave and the movable sheave of the rotating driving pulley can be
designed to be sufficiently apart that they are not in a driving
engagement with the sides of the drivebelt. The drivebelt is then
not moving and some models of driving pulleys have a bearing
provided between the two sheaves. The outer race of such bearing
supports the drivebelt when the driving pulley is in a disengaged
position. Then, when the operating conditions are such that
clutching is required, the actuation mechanism of the driving
pulley moves the sheave walls closer relative to each other. The
sheave walls eventually make contact with the sides of the
drivebelt. At this point, an axial force is applied by the
actuation mechanism on the drivebelt. The amount of torque
transferred to the drivebelt is somewhat related to this axial
force applied by the actuation mechanism. At one point, enough
friction/force is generated between the sheave walls and the
drivebelt to produce a significant force transfer between the
driveshaft and the drivebelt, thereby causing torque from the motor
to be transferred as a driving force on the drivebelt. This driving
force is transferred to the driven pulley of the CVT.
[0012] Generally, torque applied on the drivebelt will result in
vehicle acceleration at some point. The drivebelt will then
accelerate in relation to vehicle speed. At start-up, the slippage
between the driving pulley sheaves and the drivebelt is high, but
decreases as the drivebelt accelerates, to the point where it
becomes negligible and the driving pulley is considered fully
engaged.
[0013] Electronically controlled CVTs are advantageous because they
do not relate on the centrifugal force generated by the rotation of
the sheaves like legacy CVT mechanical actuation mechanisms. In
contrast, an electrically actuated CVT uses an electric motor and
an adapted gearbox to set the CVT ratio. This provides the
flexibility of using a specific CVT ratio in reaction of
predetermined conditions regardless of the centrifugal force
applied on the pulleys. Despite the advantages provided by an
electronically controlled CVT, it is appreciated that the assembly
of an electronically controlled CVT represents some challenges or
benefits not encountered with legacy CVTs.
[0014] An electronically controlled CVT uses an assisting mechanism
to manage the CVT ratio by changing the width of the driving pulley
without solely relating on centrifugal forces. The assisting
mechanism can be secured to the driving pulley preferably on the
side opposed to the engine. The assisting mechanism can be
operatively secured to the engine's drive axle without rotating
therewith. At least a portion of the assisting mechanism moves
along the engine's drive axle with the change in width between the
driving pulley sheaves. This combined movement requires an adequate
mechanical structure adapted to sustain fast repetitive movements
under significant vibrations and mechanical loads.
[0015] Gears and axles are arranged in a complex layout where small
volume and low weight are key. Other considerations also need to be
kept into account. For instance, the CVT should be easy to
assemble, inexpensive to produce and minimize the chances of errors
during the assembly process. Moreover, vibrations and rattles
should be kept to a minimum if not prevented. It is therefore
desirable to have vibration-damping parts intervening between two
CVT portions having relative axial movements therebetween.
[0016] Mechanical securing mechanisms, like splines, adapted to
join drive parts together and allow relative longitudinal movements
therebetween are generally made of steel and are significantly
heavy. Moreover, splines are not intended to sustain repetitive
relative movements between the joined parts and tend to wear
rapidly in addition to be expensive to produce. Additionally, the
design of components should consider a variety of criterions like
the mechanical resistance, the weight, the method of assembly, and
the material in addition to the effect on the cost of the assembled
final component.
[0017] Moreover, CVTs are intended to be operatively installed in a
variety of layouts. CVTs designed to be connected to an engine in a
precise arrangement are adding undesired restrictions to their
possible practical uses given the respective particularities of
each application.
[0018] Therefore, a need has been felt for an improved assisted CVT
over the prior art. It is therefore desirable to provide an
assisted CVT having a structure providing relative movements
between moveable parts of the CVT and capable of sustaining strong
vibrations and mechanical stresses while inducing reduced or no
backlash therebetween. Another need has been felt over the existing
art for an assisted CVT adapted to be installed in a variety of
positions to accommodate a plurality of operating layouts.
SUMMARY
[0019] It is one aspect of the present invention to alleviate one
or more of the drawbacks of the background art by addressing one or
more of the existing needs in the art.
[0020] At least one embodiment of the present invention provides a
slider member adapted to interconnect the two sheaves of a driving
pulley of an electronically assisted CVT. The slider member being
adapted to allow a longitudinal displacement between the two
sheaves while preventing rotational difference therebetween.
[0021] At least one embodiment of the invention provides an
assisting mechanism including a torque transmitting mechanism
adapted to provide axial displacement capabilities to the two sides
of a CVT drive sheave while transmitting rotational power
therebetween while preventing noises and rattles.
[0022] At least one embodiment of the present invention provides an
electronically assisted CVT provided with a driving pulley adapted
to sufficiently distance its two sheaves to disengage the drivebelt
therebetween.
[0023] At least one embodiment of the present invention provides an
assisted CVT provided with a driving pulley adapted to sufficiently
distance its two sheaves to disengage the drivebelt therebetween
and also provided with a vibration reducing mechanism securing an
axially movable drive sheave and reducing the sound therefrom when
the drivebelt is disengaged from the driving pulley.
[0024] At least one embodiment of the present invention provides a
toothed slider member coupling a rotatable moveable portion of the
electronically assisted CVT while allowing a relative longitudinal
movement therebetween.
[0025] At least one embodiment of the present invention provides a
slider member having vibration-damping properties to couple the
sides of a driving pulley sheave while allowing a relative
longitudinal movement therebetween.
[0026] At least one embodiment of the present invention provides a
slider member configured to provide a silent coupling of the two
sheaves of a driving pulley while allowing a relative longitudinal
movement therebetween.
[0027] At least one embodiment of the present invention provides a
backlash free slider member having vibration-damping properties to
couple two sheaves of a driving pulley while allowing a relative
longitudinal movement therebetween.
[0028] At least one embodiment of the present invention provides a
self-securing slider member adapted to limit movements thereon to a
single side thereof such that only one side of the slider member is
subject to relative movements thereon when operatively coupling two
sheaves of a driving pulley.
[0029] At least one embodiment of the present invention provides a
slider member providing discrete compression portions thereof
adapted to be compressed by the rotational load transmitted between
two sheaves of a driving pulley while allowing a relative
longitudinal movement therebetween the two sheaves.
[0030] At least one embodiment of the present invention provides a
slider member capable of being toolessly installed on an assisted
CVT drive portion.
[0031] At least one embodiment of the present invention provides a
slider member made of a light and self-lubricating material for
coupling two sheaves of a driving pulley while allowing a relative
longitudinal movement therebetween.
[0032] At least one embodiment of the present invention provides a
kit comprising a replacement slider member for coupling two sheaves
of a driving pulley while allowing a relative longitudinal movement
therebetween
[0033] At least one embodiment of the present invention provides a
star-shaped slider member.
[0034] At least one embodiment of the present invention provides a
slider member having a plurality of teeth, each tooth defining a
small variation of thickness to ensure a precise slide fit with an
intervening slider member receptacle.
[0035] At least one embodiment of the present invention provides a
slider member having alternate compression portions and junction
portions thereof.
[0036] At least one embodiment of the present invention provides a
slider member including a plurality of retaining legs axially
extending therefrom.
[0037] At least one embodiment of the present invention provides a
slider member having a diameter larger than a diameter of an
engine's drive member to which it is concentrically and rotatably
connected thereto.
[0038] At least one embodiment of the invention provides an
assisting mechanism packaged in a module secured on the axial shaft
of the CVT.
[0039] At least one embodiment of the invention presented herein
secures the assisting mechanism in cantilever on an end of the
driving pulley's axial shaft.
[0040] At least one embodiment of the present invention provides an
electronically assisted CVT assisting mechanism secured in
cantilever on a power drive of a power pack.
[0041] At least one embodiment of the present invention provides an
electronically assisted CVT adapted to angularly position the
assisting mechanism about a rotatable axial shaft of the
electronically assisted CVT's driving pulley to facilitate the
integration of the electronically assisted CVT on various
engine/motor layouts.
[0042] At least one embodiment of the assisted CVT package polarly
positionable about the axial shaft of an engine and securable at a
plurality of angular positions thereof thus providing significant
flexibility to use the assisting mechanism in various layouts.
[0043] At least one embodiment of the present invention provides an
electronically assisted CVT adapted to angularly locate an
assisting mechanism about an axial shaft of the electronically
assisted CVT to facilitate the installation of the electronically
assisted CVT on specific engine/motor layouts, the assisting
mechanism being adapted to be secured at any angle (360 degree)
about the axial shaft of the electronically assisted CVT driving
pulley.
[0044] At least one embodiment of the present invention provides an
assisted CVT with an electric actuation motor having a rotation
axis disposed parallel with the electronically assisted CVT's
driving pulley axis to minimize the size of the electronically
assisted CVT actuation package extending outside the periphery of
the electronically assisted CVT's driving pulley.
[0045] At least one embodiment of the present invention provides an
assisted CVT with an electrical actuation motor and a set of motion
transfer gears having rotatable axes parallel with the
electronically assisted CVT rotational axial shaft to minimize the
size of the electronically assisted CVT actuation package extending
outside the periphery of the sheaves of the driving pulley.
[0046] At least one embodiment of the present invention provides an
electric actuation motor having a rotational axis parallel with the
driving pulley axis and located outside the periphery of the
driving pulley and extending through a plane defined by an axially
movable sheave orthogonal to the rotation axis of the sheave.
[0047] At least one embodiment of the present invention provides a
CVT assisting mechanism secured in cantilever at a distal end of a
power drive of a power pack and provided with a retaining member
preventing rotation of the assisting mechanism with the rotation of
the power drive.
[0048] At least one embodiment of the present invention provides a
retaining member adapted to secure the assisting mechanism of an
electronically assisted CVT at a desired angle about the rotation
axis of the electronically assisted CVT driving pulley.
[0049] At least one embodiment of the present invention provides an
assisting mechanism adapted to be rotatably secured to a power
drive of an electronically assisted CVT and polarly fixedly secured
thereabout the powered drive axis with a retaining member disposed
in tension or in compression therebetween.
[0050] At least one embodiment of the present invention provides an
electronically controlled CVT driving pulley comprising a pair of
opposed sheaves adapted to rotate about a driving pulley rotation
axis, one of the sheaves including an axial protrusion including a
series of teeth cooperating with an axial bearing mechanism
providing a relative axial displacement between the opposed sheaves
and to transmit a torque between the opposed sheaves.
[0051] At least one embodiment of the present invention provides a
method for transmitting a torque between two opposed sheaves of an
electronically controlled CVT, the method comprising rotating one
of the opposed sheaves; rotating a slider member receptacle with
the one of the opposed sheaves, the slider member receptacle
engaging a slider member; and transmitting the torque to the other
opposed sheave via the slider member.
[0052] An electronically assisted CVT assisting mechanism adapted
to be secured in cantilever to a power drive, the assisting
mechanism comprising: a chassis; an actuation motor secured to the
chassis; and a main actuation gear operatively secured to a first
threaded portion and drivably connected to the actuation motor, the
first threaded portion being threadedly connected to a second
threaded portion to transfer a rotation of the main actuation gear
to a corresponding axial translation of an axially movable sheave,
the assisting mechanism being adapted to be polarly positioned
about a rotation axis of the axially movable sheave such that the
assisting mechanism could be secured at various angle about the
rotation axis of the axially movable sheave to be installed in a
variety of different layouts. Other objects, aspects and further
scope of applicability of the present invention will become
apparent from the detailed description given hereinafter. However,
it should be understood that the detailed description and specific
examples, while indicating preferred embodiments of the invention,
are given by way of illustration only, since various changes and
modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed
description.
[0053] Other embodiments, objects, aspects and further scope of
applicability of the present invention will become apparent from
the detailed description given hereinafter. However, it should be
understood that the detailed description and specific examples,
while indicating preferred embodiments of the invention, are given
by way of illustration only, since various changes and
modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed
description.
[0054] Additional and/or alternative advantages and salient
features of the invention will become apparent from the following
detailed description, which, taken in conjunction with the annexed
drawings, disclose preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE FIGURES
[0055] FIG. 1 shows a schematic illustration of a top plan view of
a wheeled vehicle with an electronically controlled CVT thereon in
accordance with an embodiment of the present invention;
[0056] FIG. 2 is a magnified isometric view of a drive portion of
the electronically controlled CVT in accordance with an embodiment
of the present invention;
[0057] FIG. 3 is an alternate magnified isometric view of the drive
portion of FIG. 2 in accordance with an embodiment of the present
invention;
[0058] FIG. 4 is a section view of the drive portion illustrated on
FIG. 2 and FIG. 3 where the sheaves are not in contact with the
drivebelt and in accordance with an embodiment of the present
invention;
[0059] FIG. 5 is a section view of the drive portion illustrated on
FIG. 2 and FIG. 3 where the sheaves are in contact with the
drivebelt and in accordance with an embodiment of the present
invention;
[0060] FIG. 6 is a semi-exploded dimetric view of the drive portion
of the electronically controlled CVT of FIGS. 2, 3, 4 and 5 in
accordance with an embodiment of the present invention;
[0061] FIG. 7 is an alternate semi-exploded dimetric view of the
drive portion of the electronically controlled CVT of FIGS. 2, 3, 4
and 5 in accordance with an embodiment of the present
invention;
[0062] FIG. 8 is an exploded dimetric view of the drive portion of
the electronically controlled CVT of FIGS. 2, 3, 4 and 5 in
accordance with an embodiment of the present invention;
[0063] FIG. 9 is a side elevational view of an illustrative
assembly of an assisting mechanism of the drive portion of the
electronically controlled CVT of FIGS. 2, 3, 4 and 5 on an engine
in accordance with an embodiment of the present invention;
[0064] FIG. 10 is a side elevational view of an alternate
illustrative assembly of an assisting mechanism of the drive
portion of the electronically controlled CVT of FIGS. 2, 3, 4 and 5
on an engine in accordance with an embodiment of the present
invention;
[0065] FIG. 11 is a side elevational view of an another
illustrative assembly of an assisting mechanism of the drive
portion of the electronically controlled CVT of FIGS. 2, 3, 4 and 5
on an engine in accordance with an embodiment of the present
invention;
[0066] FIG. 12 is an isometric exploded view of a portion of the
axially moveable sheave and slider member receptacle in accordance
with an embodiment of the present invention;
[0067] FIG. 13 is an isometric semi-exploded view of a portion of
the axially moveable sheave and slider member receptacle in
accordance with an embodiment of the present invention;
[0068] FIG. 14 is an isometric view of a portion of a sub-assembly
of the axially moveable sheave and slider member receptacle in
accordance with an embodiment of the present invention;
[0069] FIG. 15 is a top plan view of a sub-assembly of the axially
moveable sheave with the slider member receptacle slightly axially
displaced in accordance with an embodiment of the present
invention;
[0070] FIG. 16 is a top plan view of a sub-assembly of the axially
moveable sheave with the slider member receptacle slightly axially
displaced in accordance with an embodiment of the present
invention;
[0071] FIG. 17 is an isometric view of a slider member receptacle
with a slider member therein in accordance with an embodiment of
the present invention;
[0072] FIG. 18 is an section view of a slider member receptacle
with a slider member therein in accordance with an embodiment of
the present invention; and
[0073] FIG. 19 is an illustrative sectional view of a portion of a
sub-assembly of the axially moveable sheave in accordance with an
embodiment of the present invention.
DETAILED DESCRIPTION
[0074] The present invention is now described with reference to the
drawings, wherein like reference numerals are used to refer to like
elements throughout. In the following description, for purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of the present invention. It may
be evident, however, that the present invention may be practiced
without these specific details. In other instances, well-known
structures and devices are shown in block diagram form in order to
facilitate describing the present invention.
[0075] In respect with an embodiment of the invention, FIG. 1
illustrates an electronically controlled CVT 10 disposed in an
exemplary vehicle 14. The CVT 10 includes a drive portion 18 and a
driven portion 22 interconnected therebetween with a drivebelt 26.
The drive portion 18 is provided with a CVT assisting mechanism 30
adapted to set the operating ratio of the CVT 10. In the present
embodiment, the driven portion 22 is secured to an optional gearbox
34 to transmit rotational power to the drive mechanism 38 of the
vehicle 14. The gearbox 34 is not required if the driven portion 22
of the CVT 10 already rotates at a desired output speed.
[0076] The vehicle 14 schematically illustrated on FIG. 1 is
equipped with four wheels 42 like an off-road vehicle (e.g.
all-terrain vehicle . . . ) or a road vehicle (e.g. car, golf cart
. . . ). Although it is not hereby illustrated, the vehicle 14
could also be a snowmobile, a scooter, a motorcycle, an industrial
vehicle or any other devices without departing from the scope of
the present invention.
[0077] The illustrated vehicle 14 has suspension arms 46 with
interconnected springs 50 and dampers 54. The drive mechanism 38 of
the vehicle 14 includes a primary drive shaft 58 operatively
connected between an engine 62 and a differential 66, and a pair of
drive axles 70 operatively interconnected with the wheels 42. The
illustrated vehicle 14 is equipped with a rear wheel drive system.
It is understood that the present invention applied to a front
wheel drive vehicle 14 or a four-wheel drive vehicle 14 would work
in a similar fashion and is encompassed by the present
explanations. Also, we use the term "wheel" throughout the present
description although the present invention does not solely relate
to wheeled vehicles but to all vehicle having ground-contacting
members intended to support and propel the vehicle 14. Each wheel
42 supports a chassis 78 with interconnected suspension arms 46,
springs 50 and dampers 54. The front pair of wheels 82 is
interconnected with a front torsion bar 86 pivotably secured to the
chassis 78 while the rear pair of wheels 90 is interconnected with
a rear torsion bar 94 also pivotably secured to the chassis 78. The
torsion bars 86 and 94 are torsioned or twisted when the vehicle 14
is subject to roll.
[0078] FIG. 2 and FIG. 3 illustrate in more details the drive
portion 18 of the CVT 10. The drive portion 18 of the CVT 10
comprises drive pulley including a pair of opposed drive sheaves
100, a main actuation gear 104, a frame 108, a gearbox 112 and an
electric actuation motor 116. In the present embodiment, the
assisting mechanism 30 is a compact layout cooperating with the
drive sheaves 100 and removably secured to a power drive 120 of the
engine 62 (i.e. an internal combustion engine, an electric motor
not shown in FIG. 2). The electric actuation motor 116 is secured
to the frame 108 and adapted to rotate a plurality of operatively
interconnected gears housed in the gearbox 112 to ultimately rotate
the main actuation gear 104 at a desired speed.
[0079] The frame 108 of the assisting mechanism 30 of the present
embodiment consists of two frame portions 124, 128 and a support
portion 122 secured thereto. The frame 108 is adapted to receive
and secure the electric actuation motor 116 thereon. The frame 108
is also configured to enclose a set of gears 132 therein acting as
an actuation gearbox 112 to obtain the desired ratio between the
electric actuation motor 116 and the main actuation gear 104. A
sensor 140 is attached to the frame 108 to sense the position of
the set of gears 132 to monitor their position. The sensor 140 is
provided with a connecting wire 144 connectable to a wires harness
(not shown) to communicate with a control module (not shown). The
frame 108 is illustratively made of a light and strong material
like aluminum in the presented embodiment.
[0080] The opposed drive sheaves 100 are concentrically secured to
the power drive 120 of the engine 62 and adapted to rotate with the
power drive 120 about a drive axis 142. The opposed sheaves 100 of
the illustrated embodiment includes an axially fixed sheave 100.1
and an axially moveable sheave 100.2 as shown in FIG. 2 and FIG. 3.
An alternate embodiment could have a design that moves the sheave
100.1 that is proximally disposed in respect with the engine 62 and
keep the other sheave 100.2 longitudinally fixed. As best seen in
FIG. 3, the fixed sheave 100.1 is equipped with a series of radial
blades 146 adapted to act as an air pump to move air around the CVT
10.
[0081] The present embodiment illustrates that the main actuation
gear 104 is secured on a female threaded body 148 (visible in FIG.
4 and FIG. 5) that, upon rotation, transforms the rotation of the
main actuation gear 104 into a precise axial movement that impacts
the axial distance between the sheaves 100. It is the axial
position of the axially moveable sheave 100.2 (distal in respect
with the engine 62) that changes while the fixed sheave 100.1
remains axially at the same position. Any rotation of the electric
actuation motor 116 is therefore transformed into a change in
distance between both sheaves 100.1, 100.2 of the drive pulley 100
to alter the transmission ratio of the CVT 10. As a skilled reader
can understand, the axially moveable sheave 100.2 of another
embodiment could remain longitudinally fixed while it is the other
sheave 100.1, proximal to the engine 62, that longitudinally
moves.
[0082] The drive portion 18 of the embodied CVT is secured in
cantilever on the power drive 30 as it can be seen in FIG. 4. It
can be appreciated from FIG. 4 that the drive portion 18 is adapted
to be secured to the power drive 120 with a cooperating
self-centering female taper socket 156 and a long fastener 160
going through the drive portion 18, concentrically with the center
of the pair of sheaves 100.
[0083] As it is better seen in FIG. 4, the electric actuation motor
116 is operatively connected to the gearbox 112 (not visible in
FIG. 4 but is shown in FIG. 3 among other figures) that, itself, is
operatively connected to the main actuation gear 104 via an
elongated gear 152. The elongated gear 152 is provided with rather
long teeth thereof to accommodate a complete teeth-engaging axial
displacement 154 thereon of the main actuation gear 104 that
longitudinally moves along with the axially moveable sheave
100.2.
[0084] FIG. 4 illustrates the configuration where the sheaves 100
are disposed at their maximum distance therebetween. The main
actuation gear 104 is thus distally contacting the elongated gear
152. In contrast, FIG. 5 illustrates the same CVT 10 in a
configuration where the sheaves 100 are disposed at their closest
distance therebetween; it is possible to appreciate that the main
actuation gear 104 contacts the elongated gear 152 on the proximal
side.
[0085] One can see from FIG. 4 that the main actuation gear 104 is
removably secured to a female threaded body 148 rotated thereby
upon actuation of the electric actuation motor 116. The female
threaded body 148 engages a counterpart male threaded body 164,
which is secured to the frame 108, to create a threaded interface
168 therebetween. A rotational movement of the female threaded body
148 is therefore transformed into an axial movement due to the
threaded interface 168. The female threaded body 148 experiences
the entire axial displacement because the male threaded body 164
does not longitudinally move relatively to the frame 108 and the
axial shaft 172. This axial displacement of the female threaded
body 148 is communicated by the main actuation gear 104, which is
rotated by the elongated gear 152. In other words, the electric
actuation motor 116, fixedly connected to the frame 108, can apply
a controlled rotational displacement of the main actuation gear 104
to axially move the axially moveable sheave 100.2 via the threaded
interface 168.
[0086] Still referring to FIG. 4, the assisting mechanism 30 is
supported by the distal end of the rotating axial shaft 172. A pair
of intervening support bearings 176 allows rotational movements
between the assisting mechanism 30 and the axial shaft 172. The
pair of support bearings 176 also allows the assisting mechanism 30
to be angularly secured about the axial shaft 172 when the
electronically controlled CVT 10 is positioned and secured in its
final operative layout.
[0087] The elongated gear 152, well illustrated in FIG. 4 and in
FIG. 5, is elongated because it is operatively engaging the axially
moveable main actuation gear 104. The elongated gear 152 is
longitudinally fixedly positioned in respect with the distal end of
the axial shaft 172 and has an effective length 154 that
corresponds with the axial displacement of the main actuation gear
104 that is at least as long as the maximum operating axial
distance variation between both sheave 100.
[0088] In reference with FIG. 2 through FIG. 5, the axis 188 of the
elongated gear 152 is parallel with the drive axis 142. The
elongated gear 152 extends outside the periphery of the axially
moveable sheave 100.2 and is driven by the main actuation gear 104
that has a diameter that is larger than the diameter of the axially
moveable sheave 100.2. The rotation axis 192 of the electric
actuation motor 116 is parallel with the drive axis 142. Similarly,
the electric actuation motor 116 extends outside the periphery of
the axially moveable sheave 100.2.
[0089] Still referring to FIG. 4 and FIG. 5 where is illustrated a
neutral bearing 180 disposed on the axial shaft 172 between the
sheaves 100. A cavity 184 is formed in the axially moveable sheave
100.2 to receive the neutral bearing 180 therein when both sheaves
100 are closer to engage and rotate the drive belt 26 on a larger
operating diameter. The neutral bearing 180 supports the drive belt
26 and prevents it to friction the rotating axial shaft 172 when
both sheaves 100 are distanced enough from each other by the
assisting mechanism 30 to disengage the sides of the drive belt 26
from the sheaves 100. The CVT is in the "neutral" position (meaning
the belt 26 is not driven by the drive pulley 100) when the drive
belt 26 is laterally uncompressed between the sheaves 100. The
sheaves 100 continue to rotate with the power drive 120 when the
CVT is in the "neutral" position. The axially moveable sheave 100.2
is coupled to the axially fixed sheave 100.1 by the axial shaft 172
and rotates when the CVT is in the "neutral" position. Reducing the
distance between both sheaves 100 with the assisting mechanism 30
reengages the drive belt 26. The friction between the drive belt 26
and both sheaves 100 progressively engages the drive belt 26 until
the drive belt 26 is propelled by the rotating sheaves 100. Put
differently, the electronically controlled CVT 10 in accordance
with the present embodiment is equipped with a disengagement
mechanism. The disengagement mechanism is not a centrifugal clutch
as commonly used in legacy CVTs. Disengagement is produced by
managing the distance between the sheaves 100 of the drive pulley
with the assisting mechanism 30 to a point where the drivebelt 26
does not operatively contact the sheaves 100 nor the axial shaft
172 and freely rests on the neutral bearing 180. Reengagement of
the drivebelt 26 is managed by the assisting mechanism 30 by
reducing the distance between the sheaves 100 to contact and move
the drive belt 26 to rotate the driven portion 22.
[0090] FIG. 6 and FIG. 7 depict a semi-exploded drive portion 18.
The axially fixed sheave 100.1 (left) is adapted to receive the
axially moveable sheave 100.2 (right) on the axial shaft 172. The
hollowed axial shaft 172 is sized and designed to receive the long
fastener 160 therein to secure the assembly to the power drive 120
of the engine 62.
[0091] Turning now to FIG. 8 illustrating in more details an
embodiment of the present invention. The exploded view of the drive
portion 18 of the CVT 10 depicted in FIG. 8 teaches in further
details how the drive portion 18 is assembled. Beginning with the
fixed sheave 100.1, from which extends the axial shaft 172 to which
is assembled thereon the axially moveable sheave 100.2. The main
actuation gear 104 is fixedly secured to the female threaded body
148 that is adapted to cooperate with corresponding male threaded
body 164. The male threaded body 164 is secured to the support
portion 122 and acts as an abutment when the female threaded body
148 is screwed thereon moving axially following the threads of the
threaded interface 168 created thereby. The longitudinal
displacement of the female threaded body 148 moves both the main
actuation gear 104 and the axially moveable sheave 100.2. Bearings
176 intervene between the female threaded body 148 and the axially
moveable sheave 100.2 to prevent the main actuation gear 104 to
rotate with the sheaves 100 and the axial shaft 172. The male
threaded body 164 and the female threaded body 148 could be
inverted, if properly designed, such that the male threaded body
164 receives the main actuation gear 104 thereon.
[0092] An intervening slider member receptacle 196 is provided to
support the distal end of the axial shaft 172 and to support
thereon the support portion 122 of the assisting mechanism 30. The
slider member receptacle 196 also slideably receives therein the
shaped protruding end 200 of the axially moveable sheave 100.2 and
supports thereon its associated main actuation gear 104. The
cylindrical external shape of the slider member receptacle 196 is
sized and designed to fit in corresponding opening in the support
portion 122 and to accommodate a slider member 204 therein. The
slider member 204 intervening between the internally located distal
protruding end 200 of the axially moveable sheave 100.2 and the
internal shape of the slider member receptacle 196. The slider
member 204 has a shape adapted to transmit rotational movement
while allowing a smooth axial movement between the distal end of
the axially moveable sheave 100.2 and the slider member receptacle
196. The slider member 204 also acts as a vibration damper between
the two components thus preventing or reducing possible rattles.
Additionally, a bearing-receiving unit 208 is concentrically
mounted at the distal end of the slider member receptacle 196 to
support the distal end of the rotating assembly by rotatably
engaging a bearing 176 secured in the fixed male threaded body
164.
[0093] Still in FIG. 8, the elongated gear 152 is associated with
an adjacent larger gear 212 and other gears 132 to further change
the gear ratio. Complementary gears 216 and 220 are arranged to
provide a proper teeth-moving frequency for the sensor 140 to
sense. The sensor 140 senses when each teeth of the gear 220 passes
nearby and changes state and/or sends a signal thereof to a control
system (not shown) monitoring and managing the assisting mechanism
30.
[0094] One advantage of the assisting mechanism 30 is it can be
secured in one piece at the end of an axial shaft 172. Referring
now to FIG. 9 through FIG. 11 where it can be appreciated the
assisting mechanism 30 could be secured to various polar locations
about the driving pulley axis 142. The assisting mechanism 30 is
located in FIG. 9 to the left of the driving pulley 100 at an angle
a in respect with the horizontal. In contrast, the assisting
mechanism 30 is respectively located upward at an angle .beta. in
FIG. 10 and downward at an angle .gamma. in FIG. 11. In the
illustrated embodiments, the assisting mechanism 30 is secured into
position with a retaining member 224. The retaining member 224 is
either arranged to work in tension or in compression. Both
configurations are illustrated in FIG. 9. Generally, a single
retaining member 224 is sufficient to resist drag torque in
assisting mechanism 30 bearings 176 about the rotatable axial shaft
172. The retaining member 224 of one embodiment is a rigid bracket
illustratively made of aluminum or steel. The retaining member 224
could alternatively be a bracket made of a flexible material
illustratively made of plastic or rubber and adapted to allow some
relative movement between the assisting mechanism 30 and the engine
62.
[0095] The retaining member 224 is preferably mounted to the engine
62 to limit the rotational relative movement between the assisting
mechanism 30 and the structure to which it is connected to while
allowing free rotation of the axial shaft 172. It is possible to
secure the retaining member 224 on another portion of the vehicle
14, like, for example, the frame 78 of the vehicle 14.
[0096] The assisting mechanism 30 of embodiments of the present
invention is secured in cantilever to an axial shaft 172 of a CVT
10. This provides significant possibilities to retrofit the
assisting mechanism 30 to a variety of CVTs. The retaining member
224 of an embodiment prevents against rotation of the assisting
mechanism 30 with the rotating axial shaft 172 without applying
additional stresses to the axial shaft 172 and the power drive 120.
A more rigid retaining member 224 would likely induce additional
undesirable stresses to the axial shaft 172 and the power drive 120
because it is a hyperstatic assembly. (A hyperstatic assembly is a
non-isostatic assembly like, for example, a chair with four legs.
The chair would be stable with three legs, even with reasonably
different lengths. The fourth leg, if it is not exactly at the
proper length, would induce stress in the chair if all legs are
secured to the ground.)
[0097] In another embodiment, the retaining member 224 is either
integrated in the engine 62, the frame 78 or built in another part
of the assisting mechanism 30. The frame 78 could, for instance,
have a shape suitable to be directly secured to a nearby structure
in order to prevent the assisting mechanism 30 to rotate or pivot
about the driving pulley axis 142. Put differently, in accordance
with at least one embodiment of the invention, the retaining member
224 is a retaining portion built in another part of the assisting
mechanism 30, the engine 62 or the vehicle 14.
[0098] The compact layout of the assisting mechanism 30 of the
present embodiment facilitates its location nearby the driving
pulley axis 142. The assisting mechanism 30 is capable of being
secured at any angle about the driving pulley axis 142.
[0099] The electric motor 116 and the elongated gear 152 are
located on the assisting mechanism 30 to create a very compact
assisting mechanism 30 layout. As it is illustrated in FIG. 4 and
FIG. 5, the elongated gear 152 can extend in the plane defined by
the axially moveable shave 100.2. The electric motor 116 (not
visible in FIG. 5 and FIG. 6) also extends within the plane defined
by the axially moveable sheave 100.2. The axis of the electric
motor 116 is substantially parallel with the axis 188 of the
elongated gear 152. The electric motor 116 can alternatively be
disposed in the opposite direction, keeping its rotational axis at
the same place while distally extending from the sheaves 100. In so
doing, the electric motor 116 is further away from the drive belt
26 and the assisting mechanism 30 could be located even closer to
the drive sheaves 100.
[0100] FIG. 12 through FIG. 14 illustrates a magnified exploded
view of the axially movable sheave 100.2 of the CVT driving pulley.
The axially movable sheave 100.2 is configured to be mounted on the
axial shaft 172 (not visible on FIG. 13 but visible on FIG. 7)
extending from the axially fixed sheave 100.1. The axially movable
sheave 100.2 is provided with a protruding end 200 on its distal
side thereof. The protruding end 200 includes a series of radially
elongated teeth 202 and each tooth 202 has a profile adapted to
operatively cooperate with a corresponding internal toothed shape
of the slider member 204.
[0101] The protruding end 200 also defines a bearing area 206 sized
and designed to receive the support bearing 176 thereon. The
support bearing 176 rotatably receives the female threaded body 148
thereon (not visible on FIG. 12 through FIG. 14). In turn, the
female threaded body 148 is configured to accommodate thereon the
main actuation gear 104 (not visible on FIG. 12 through FIG. 14) to
also axially secure the axially movable sheave 100.2. A circlip 178
further secures the support bearing 176 to the protruding end 200
in the present embodiment.
[0102] The series of radially elongated teeth 202 of the protruding
end 200 are sized and designed to be inserted in the slider member
204 that it is sized and designed to be inserted in the slider
member receptacle 196. The slider member receptacle 196 is
internally provided with a corresponding series of internal teeth
198 adapted to mate with the external shape of the slider member
204. This arrangement of parts prevents relative rotation between
the slider member receptacle 196, the intervening slider member 204
and the elongated teeth 202 of the protruding end 200 from the
axially movable sheave 100.2.
[0103] While the slider member 204 bears the rotational load and
the vibrations between the protruding end 200 and the slider member
receptacle 196, a pair of bearing members 194 is respectively
disposed on each opposite axial side, inside the protruding end
200. The pair of slider members 194 bears the radial loads between
the protruding end 200 and the axial shaft 172 (not visible on
these figures but visible on FIG. 6 among other). The slider
members 194 are secured in the axial bore of the protruding end 200
and further secured with a circlip 178 to prevent any undesirable
axial extraction.
[0104] The final mechanical assembly, which can be appreciated in
FIG. 14, allows the series of radially elongated teeth 202 to mate
with the corresponding internal teeth 198 of the slider member 196
and the exterior shape of the slider member 204 to mate with the
series of corresponding internal teeth 198 of the slider member
receptacle 196. Once assembled, the axially movable sheave 100.2 is
rotatably secured to the slider member receptacle 196, via the
slider member 204, while remaining free to move axially thereof.
The slider member receptacle 196, via the bearing-receiving unit
208, engages a support bearing 176 (not illustrated on FIG. 14 but
visible in FIG. 7) to support the distal end of the protruding end
200. No axial movement occurs between the slider member receptacle
196, the bearing-receiving unit 208 assembly and the support
portion 122 assembly.
[0105] It can be appreciated that the slider member 204 is
preferably made of plastic material. A compression resistant and
somewhat lubricating plastic would be beneficial to the assembly.
The shape of the slider member 204 is also designed to avoid any
unnecessary material to lighten the rotatable assembly. The slider
member 204 defines a series of radially positioned compression
portions 226 (best seen on FIG. 12) adapted to intervene between
each tooth of the series of radially elongated teeth 202 and
counterpart opposed teeth of the series of internal teeth 198
included inside the slider member receptacle 196. Therefore, the
rotational force generated between cooperative teeth 198 and 202 is
transmitted via a respective compression portion 226 when the
axially movable sheave 100.2 rotates with the axially fixed sheave
100.1.
[0106] Each compression portion 226 is connected to juxtaposed
compression portions 226 via an intervening junction portion 228.
Junction portions 228 are preferably made with less material since
they are not compressed and less mechanically solicited when the
axially movable sheave 100.2 rotates and rotatably drives the
slider member receptacle 196. A suite of alternate compression
portions 226 and junction portions 228 are forming the slider
member 204.
[0107] Compression portions 226 are disposed radially in respect
with the drive axis 142 and therefore follow the radial surfaces of
the teeth 198, 202. In contrast, the junction portions 228
proximally and distally alternate between two adjacent compression
portions 226, to follow the interstitial gap between the
cooperating teeth 198, 202.
[0108] Referring now to FIG. 12 and FIG. 15 through FIG. 17 where
it can be appreciated that the slider member 204 comprises a number
of anti-backlash and/or anti-rattle features to prevent any
undesirable play between the cooperating teeth 198, 202 that could
generate undesirable noise and/or rattles when the electrically
controlled CVT 10 is in operation. One anti-backlash feature is a
series of legs 230 axially extending from each junction portion 228
of the slider member 204. Each pair of legs 230 simultaneously
contacts both radial sides of a corresponding axially elongated
tooth 202 of the protruding end 200. Each pair of legs 230 slides
along its related elongated teeth 202 to help prevent any
mechanical play. Each pair of legs 230 is further press fitted on
the elongated teeth 202 when it reaches a wider elongated teeth
axial root 232 to even further prevent any undesirable play
therebetween. The pair of legs 230 is pushed apart by the wider
root 232 portions of the radially elongated teeth 202 and a
non-permanent press fit is provided therebetween.
[0109] A series of valleys 234 is defined between adjacent
elongated teeth 202. The proximal axial portion of the valley 234
is provided with a progressively shallower region where the valley
234 radially raises such that each leg 230 is also radially
distally pressured to further secure the slider member 204 to the
protruding end 200. In other words, the elongated teeth 202
radially and tangentially pressures each leg 230 when the slider
member 204 is pushed toward the root 232 of the elongated teeth
202. The sort of press fit occurring against the series of radially
elongated teeth 202 helps preventing relative movements and
backlashes with the slider member 204. It also helps to secure the
assembly and make sure that, when the slider member receptacle 196
axially moves in respect with the radially elongated teeth 202, the
only efficient bearing area is between the protruding end 200 and
the slider member 204. It is encompassed by the present invention
that the opposite bearing arrangement is also a practical workable
embodiment.
[0110] It can be appreciated from the illustrated embodiment that
the driving sheave 100 is open and does not contact the drive belt
26 when the protruding end 200 is profoundly inserted in the slider
member receptacle 196. In other words, the CVT is at the neutral
position. This is where the two sheaves 100.1 and 100.2 are the
most likely to vibrate because they are freely rotating without
transmitting power, more subject to the engine's 62 speed and/or
torque variations and further because they are not interconnected
by the drivebelt 26 applying pressure thereof. This sensitive
position of the axially movable sheave 100.2 is also where the legs
230 of the slider member 204 are contacting the wider root 232 thus
establishing a stronger contact with the elongated teeth 202 to
prevent any play thereof.
[0111] The anti-backlash features of the present embodiment also
include a series of axial stems 236 that can additionally be
appreciated on the figures. Axial stems 236 are disposed on the
proximal axial side of each radial and distal junction portion 228
of the slider member 204 to further secure the slider member 204 in
the slider member receptacle 196. Axial stems 236 make sure the
slider member 204 is firmly secured in the slider member receptacle
196 by engaging the groove (or the slot 240) located on the
proximal side of the internal wall portion of the slider member
receptacle 196 (best seen in FIG. 17 through FIG. 19).
[0112] A skilled reader will appreciate that the slider member 204
is slidably and removably secured to the series of radial elongated
teeth 202 and provides a backlashless fit thereof. Therefore, the
rotational movement of the axially fixed sheave 100.1 is
communicated to the slider member receptacle 196 that rotates the
axially movable sheave 100.2 while a relative axial movement
therebetween is allowed to set the distance between both sheaves
100.1, 100.2 of the driving pulley when the CVT assisting mechanism
30 adjust the electronically assisted CVT 10 ratio.
[0113] The description and the drawings that are presented above
are meant to be illustrative of the present invention. They are not
meant to be limiting of the scope of the present invention.
Modifications to the embodiments described may be made without
departing from the present invention, the scope of which is defined
by the following claims:
* * * * *