US20110152020A1

US20110152020A1 - Electronically controlled continuously variable transmission with axially movable torque transmitting mechanism

Info

Publication number: US20110152020A1
Application number: US12/976,773
Authority: US
Inventors: François Brind'Amour; Hubert Roberge; Lionel Thiébault
Original assignee: Individual
Current assignee: CVtech Inc
Priority date: 2009-12-23
Filing date: 2010-12-22
Publication date: 2011-06-23
Also published as: CA2727789A1; US20110153174A1; CA2725516A1; CA2725516C; US8682549B2

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.

Description

CROSS-REFERENCE

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

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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
At least one embodiment of the present invention provides a slider member capable of being toolessly installed on an assisted CVT drive portion.
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.
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
At least one embodiment of the present invention provides a star-shaped slider member.
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.
At least one embodiment of the present invention provides a slider member having alternate compression portions and junction portions thereof.
At least one embodiment of the present invention provides a slider member including a plurality of retaining legs axially extending therefrom.
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.
At least one embodiment of the invention provides an assisting mechanism packaged in a module secured on the axial shaft of the CVT.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

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;

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;

FIG. 3 is an alternate magnified isometric view of the drive portion of FIG. 2 in accordance with an embodiment of the present invention;

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;

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;

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;

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;

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;

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;

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;

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;

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;

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;

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;

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;

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;

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;

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

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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 β in FIG. 10 and downward at an angle γ 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.
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.
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.)
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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:

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.