CROSS REFERENCE TO PRIOR APPLICATION

The present case claims the benefits of U.S. patent application No. 62/771,828 filed 27 Nov. 2018. The entire contents of this prior patent application are hereby incorporated by reference.

TECHNICAL FIELD

The technical field relates generally to continuously variable transmissions (CVTs).

BACKGROUND

CVTs are commonly used on a wide range of vehicles, such as small cars or trucks, snowmobiles, golf carts, scooters, etc. They generally include a driving pulley mechanically connected to a motor, a driven pulley mechanically connected to wheels or a track, often through another mechanical device such as a gearbox, and a trapezoidal drivebelt transmitting torque between the driving pulley and the driven pulley. A CVT automatically changes the ratio as required by load and speed conditions, providing a high torque under high loads at low speeds and yet controlling the rotation speed of the motor as the vehicle accelerates. A CVT may be used with all kinds of motors, such as internal combustion engines or electric motors, to name just a few.

The sides of the drivebelt are, on each pulley, gripped between opposite conical walls of two coaxially mounted sheaves. One sheave is referred to as the fixed sheave and is mounted to one end of a support shaft. This other sheave is referred to as the movable sheave and is free to move along the support shaft with reference to the fixed sheave, for instance by means of bushings or the like. The relative axial position of the sheaves changes the winding diameter of the drivebelt on each pulley.

At a low vehicle speed, the winding diameter of the drivebelt at the driving pulley is minimal and the winding diameter at the driven pulley is maximal. This is referred to as the minimum ratio since there is the minimum number of rotations or fraction of rotation of the driven pulley for each full rotation of the driving pulley. Generally, when the rotation speed of the driving pulley increases, its movable sheave moves closer to the fixed sheave thereof under the effect of a control mechanism, for instance a centrifugal 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. The radial force is counterbalanced at least in part by a return force, for instance a return force generated by a spring inside the driven pulley and/or by another biasing mechanism. 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 results from the presence of a cam system and/or another biasing mechanism provided to move the movable sheave towards the fixed sheave as the torque increases. A cam system generally includes a plurality of ramp surfaces on which respective followers can be engaged. The followers can be, for instance, sliding buttons or rollers. The set of ramp surfaces or the set of followers is mounted to the movable sheave. The other set can be mounted to the support shaft of 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. Then, when the vehicle speed decreases, the rotation speed of the driving pulley eventually decreases as well since the rotation speed of the motor will decrease at one point. Ultimately, this causes 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 its biasing mechanism, for instance a spring, moves the movable sheave closer to the fixed sheave.

Some CVTs are provided with a reversible driven pulley. A reversible driven pulley is not limited to only provide control in a forward mode and operates in a similar fashion to one that is not, with the exception that the transmission ratio can be controlled during motor braking when the vehicle travels in a forward direction, or be controlled when the vehicle accelerates in a backward direction and the direction of the torque received from the motor is changed. These instances are generically referred to as the motor braking mode and the reverse mode, respectively. During the motor braking mode, the torque is no longer coming from the motor to the wheels or track of the vehicle, but in the opposite direction. In the reverse mode, the vehicle accelerates backwards by changing the direction of the torque received from the motor delivered at the CVT, as aforesaid. Various arrangements can be used to change the direction of the torque and bring the CVT in the reverse mode. For instance, if the vehicle is driven by an electric motor, the electric motor can be a bidirectional motor. In the case of an internal combustion engine, it is also possible to change the direction of rotation using an electric controller capable of selecting in which direction the engine rotates. Another possible approach is to use a gearbox capable of selectively reversing the direction of its output torque, which output torque is then delivered to the CVT.

A reversible driven pulley includes a second set of ramp surfaces and sometimes a second set of followers if the first set of followers is not designed to be used with the second set of ramp surfaces. The first set of ramp surfaces is used when the torque received from the motor is in one direction (forward mode), and the second set of ramp surfaces is used during a motor braking mode or when the torque received from the motor is in the opposite direction (reverse mode).

It is worth mentioning that there is possibly a motor braking mode when the vehicle travels in a backward direction. However, given the fact that most vehicles travel backwards only on very short distances, such mode is rarely considered in the design of a driven pulley. Nevertheless, a designer may choose to design a driven pulley with such mode.

It is generally desirable that the maximum ratio of a CVT be as high as possible. The minimum winding diameter at the driven pulley is one of the limiting factors. The presence of various parts between the bottom of the belt-receiving groove and the support shaft is an obstacle to a more compact design. Yet, some configurations can be very difficult or sometimes even impossible to achieve if the available space around the CVT cannot be increased. Overall, there is still room for further improvements in this area of technology.

SUMMARY

In one aspect, there is provided a driven pulley for use in a continuously variable transmission having a drivebelt, the driven pulley being coaxially mountable around a support shaft and including: a fixed sheave having opposite front and rear sides, the front side of the fixed sheave being provided with a conical wall; a movable sheave coaxial with the fixed sheave and having opposite front and rear sides, the front side of the movable sheave being provided with a conical wall facing the conical wall of the fixed sheave to form a drivebelt-receiving groove; a support coaxial with the two sheaves, the support being at a fixed axial distance from the fixed sheave and facing the rear side of the movable sheave; at least two axisymmetric first cam surfaces provided on one among the rear side of the movable sheave and the support; a set of first cam followers provided on the other one among the second side of the movable sheave and the support, each first cam follower being engageable with a respective one of the first cam surfaces; a biasing element provided between the movable sheave and the support; first means for providing a direct torque- transmitting engagement between the sheaves while allowing a relative axial motion between them, the first means being located within an annular space between the support shaft and a bottom of the belt-receiving groove; second means for pivotally connecting the fixed sheave on the support shaft; third means for pivotally and slidably connecting the movable sheave on the support shaft; and fourth means for rigidly connecting the support to the support shaft.

In another aspect, there is provided a driven pulley, as shown, described and/or suggested herein.

In another aspect, there is provided a method of manufacturing a driven pulley, as shown, described and/or suggested herein.

In another aspect, there is provided a CVT including a driven pulley, as shown, described and/or suggested herein.

More details on the various aspects, features and advantages of the proposed concept can be found in the following detailed description and the appended figures. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-section view of a continuously variable transmission (CVT) incorporating an example of a driven pulley as improved;

FIG. 2 is a semi-schematic top view illustrating the CVT of FIG. 1 installed in a generic vehicle; FIG. 3 is a first isometric view of the driven pulley in FIG. 1, the driven pulley being at the minimum ratio position;

FIG. 4 is a side view of the driven pulley shown in FIG. 3;

FIG. 5 is a second isometric view of the driven pulley shown in FIG. 3;

FIG. 6 is a view similar to FIG. 3 but with a cutaway section; FIG. 7 is a cross-section view of the driven pulley shown in FIG. 3;

FIG. 8 is an isometric view illustrating the front side of the movable sheave in the driven pulley shown in FIG. 3;

FIG. 9 is an isometric view illustrating the rear side of the fixed sheave in the driven pulley shown in FIG. 3; FIGS. 10 and 11 are enlarged isometric views of the central hub of the fixed sheave in the driven pulley shown in FIG. 3;

FIGS. 12 and 13 are isometric views of the fixed sheave and the support shaft in the driven pulley shown in FIG. 3;

FIG. 14 is an enlarged view of one of the inserts provided in the passageways of the driven pulley shown in FIG. 3;

FIG. 15 is an enlarged exploded view showing how an insert can be positioned into a passageway;

FIGS. 16 and 17 are isometric views of the support in the driven pulley shown in FIG. 3;

FIG. 18 is a side view of the driven pulley shown in FIG. 3, the driven pulley being now at the maximum ratio position; FIG. 19 is a cross-section view of the driven pulley shown in FIG. 18;

FIGS. 20 and 21 are isometric views similar to FIGS. 3 and 5 but showing a variant of the driven pulley as improved where the hub is made integral with the rest of the fixed sheave;

FIG. 22 is a cross-section view of the driven pulley shown in FIGS. 20 and 21; FIG. 23 is a cross-section view of a variant of the driven pulley as improved;

FIG. 24 is a cross-section view of another variant of the driven pulley as improved;

FIG. 25 is a cross-section view of a CVT incorporating an example of a known driven pulley;

FIG. 26 is a semi-schematic top view illustrating the CVT of FIG. 25 installed in the same generic vehicle as in FIG. 2; and FIGS. 27 and 28 are cross-section views provided for dimensional comparisons between the driven pulleys in FIGS. 1 and 25.

DETAILED DESCRIPTION

FIG. 1 is a cross-section view of a continuously variable transmission (CVT) 100 incorporating an example of a driven pulley 200 as improved herein. The CVT 100 also includes a driving pulley 102 and a trapezoidal drivebelt 104. The illustrated driving pulley 102 is only an example provided for the sake of illustration and many other possible configurations or arrangements exist. The driven pulley 200 can thus be used with a different kind of driving pulley.

The driving pulley 102 includes a fixed sheave 110 and a movable sheave 112. The fixed sheave 110 is so-called because, during operation, it remains at the same axial position along a support shaft 114 on which it is mounted. The movable sheave 112 is axially movable along the support shaft 114 with reference to the fixed sheave 110 and is so-called for this reason. The position of the movable sheave 112 is governed by a control mechanism, for instance a centrifugal mechanism 116 with flyweights as shown. Other kinds of control mechanisms can be used as well, such as an electromechanical mechanism, a hydraulic mechanism, etc. The support shaft 114 of the driving pulley 102 is designed to be mounted on the output shaft of a motor, for instance an internal-combustion engine, an electric motor or any other suitable kind of motor capable of generating torque. The driving pulley 102 can also be mounted on a shaft that is not directly located at the output of the motor.

The driving pulley 102 of FIG. 1 is designed for use with an internal-combustion engine. In the illustrated example, the movable sheave 112 is farther than the width of the drivebelt 104 when the rotation speed of the driving pulley 102 is below a certain threshold, for instance when the engine is at idle speed. The centrifugal mechanism 116 does not generate enough axial force to counterbalance a return spring 118 and this caused the distance between the sheaves 110, 112 to be maximum. No motive power is transmitted from the driving pulley 102 to the drivebelt 104. This situation can be referred to as the unclutched position. Furthermore, the illustrated driving pulley 102 includes a bearing arrangement 120 mounted around the support shaft 114 at the bottom of the drivebelt-receiving groove. This bearing arrangement 120 includes one or more bearings, for instance ball bearings or the like, to support the interior of the drivebelt 104. When the driving pulley 102 is in the unclutched position, the bearing arrangement 120 minimizes the forces transmitted from the driving pulley 102 to the drivebelt 104 and the driving pulley 102 simply rotates at the engine idle speed.

Some implementations may use a bearing arrangement 120 having a one-way mechanism therein. Different kinds of devices are possible. A one-way bearing arrangement 120 allows the driving pulley 102 to rotate at idle speed without transmitting any significant force to the drivebelt 104, for instance when the engine is started and the vehicle is not moving. However, it allows torque to be transmitted from the drivebelt 104 to the driving pulley 102, even if it is in the unclutched position, as soon as the outer race of the bearing arrangement 120 rotates faster than the rest of the driving pulley 102. This situation may occur, for instance, when the vehicle travels down a hill and the engine is at idle speed. The one-way bearing arrangement 120 can automatically initiate a motor braking mode in such circumstance since it can force the driving pulley 102, along with the engine, to rotate faster. This increase in the rotation speed will eventually activate the centrifugal mechanism 116 to reduce the distance between the two sheaves 110, 112 enough to put them into a full engagement with the lateral sides of the drivebelt 104. This capability can be referred to as a self-activated engine braking (SAEB). If the bearing arrangement 120 is not a one-way bearing, or if no bearing arrangement is present at all, then the engine braking will not occur unless the driver of the vehicle voluntary increases to engine speed just enough to at least pinch the drivebelt 104 between the sheaves 110, 112. This situation can be referred to as a driver-activated engine braking (DAEB). A driver can activate engine braking even if the CVT has a SAEB capability but a CVT without a SAEB capability will not go into an engine braking mode by itself.

When designing a CVT with a SAEB capability, it is generally desirable that the driven pulley includes a full-torque configuration, namely that the two sheaves of the driven pulley be in a direct torque-transmitting engagement. In a driven pulley that does not have a full-torque configuration, the fixed sheave is in a direct torque-transmitting engagement with the support shaft of the driven pulley and about half the torque received from the drivebelt 104 goes from the fixed sheave directly to the support shaft. The other half goes through the movable sheave and is transmitted to the support shaft by the cam system. Because a different set of cam surfaces is engaged by the followers during motor braking, the transition between the sets of cam surfaces creates a relative angular displacement of the movable sheave with reference to the support shaft of the driven pulley. The fixed sheave does not follow the rotation of the movable sheave when it is in a direct torque- transmitting engagement with the support shaft and this results in shear forces on the drivebelt. This is prevented in a full-torque configuration because the fixed sheave and the movable sheave do not pivot relative to one another.

FIG. 2 is a semi-schematic top view illustrating the CVT 100 of FIG. 1 installed in a generic vehicle 130. This example is only for the sake of illustration and there are numerous other possible configurations and arrangements. The vehicle 130 includes an engine 132, and the driving pulley 102 of the CVT 100 is mounted at the end of an output shaft thereof. The driven pulley 200 is mounted at the end of an input shaft of a gearbox 134. This gearbox 134 is connected to the driving wheels of the vehicle 130 by a driveshaft 136 and other powertrain components. Other configurations and arrangements are possible as well.

FIG. 3 is a first isometric view of the driven pulley 200 in FIG. 1, the driven pulley 200 being at the minimum ratio position. The driven pulley 200 includes a fixed sheave 210 having opposite front and rear sides. FIG. 3 shows the rear side of the fixed sheave 210. The front side of the fixed sheave 210 includes a conical wall 212 extending on a major portion of its radius. The driven pulley 200 also includes a movable sheave 214 that is coaxial with the fixed sheave 210. The movable sheave 214 has opposite front and rear sides, the front side of the movable sheave 214 being provided with a conical wall 216. The conical wall 216 of the movable sheave 214 faces the conical wall 212 of the fixed sheave 210 to form a drivebelt-receiving groove 218, as shown in FIG. 4. FIG. 4 is a side view of the driven pulley 200 shown in FIG. 3.

FIG. 5 is a second isometric view of the driven pulley 200 shown in FIG. 3.

The driven pulley 200 also includes a radially extending support 220 coaxial with the fixed and movable sheaves 210, 214. This support 220 is at a fixed axial distance from the fixed sheave 210 and faces the rear side of the movable sheave 214. In the illustrated example, the support 220 is in the form of a cam plate supporting a plurality of axisymmetric cam surfaces 222, 224. There are two sets of cam surfaces 222, 224 in the illustrated example and each set includes two cam surfaces. Each first cam surface 222 faces a corresponding adjacent one of the second cam surface 224. The set of first cam surfaces 222 is provided for the forward mode and the set of second cam surfaces 224 is provided for the motor-braking mode. Other configurations and arrangements are possible. For instance, the set of second cam surfaces 224 can be omitted in some implementations. Likewise, it is possible to have only two cam surfaces in a given set or more than three. Other variants are possible as well.

The illustrated cam surfaces 222, 224 are designed to be engaged by respective followers 230, 232 provided, in this implementation, on the rear side of the movable sheave 214. In the illustrated example, a pair of the two followers 230, 232 is located on a double-sided sliding button affixed into a corresponding clamp 234 by a fastener 236, for instance a threaded fastener such as a bolt or screw. Other configurations and arrangements are possible. Among other things, the same follower can also be designed to engage both a first cam surface 222 and an adjacent second cam surface 224. The followers can be in the form of rollers. Other kinds of followers are possible as well. Still, the relative position of the cam surfaces 222, 224 and that of the followers 230, 232 can be inverted. The cam surfaces 222, 224 would then be provided on the rear side of the movable sheave 214 and the followers 230, 232 would be provided on the support 220. Other variants are possible as well.

It should be noted that the engine 132 in the example shown in FIG. 2 is rotating clockwise when viewed from the left side of the CVT 100. FIG. 4 thus shows the follower 230 engaging its corresponding first cam surface 222 like when the vehicle 130 accelerates in the forward travel direction. The opposite follower 232 will engage its corresponding second cam surface 224 when the vehicle 130 is in a motor-braking mode. Some motors are designed to rotate counterclockwise, even when moving in the forward travel direction and accordingly, the cam surfaces 224 would be engaged by the followers 232 when the vehicle 130 accelerates in the forward travel direction. FIG. 6 is a view similar to FIG. 3 but with a cutaway section.

FIG. 7 is a cross-section view of the driven pulley 200 shown in FIG. 3. FIG. 7 shows, among other things, a support shaft 240 around which the various components of the driven pulley 200 can be mounted. This support shaft 240 includes a plurality of longitudinally disposed axisymmetric internal splines 242 to ensure a good torque-transmitting engagement with the input shaft of the gearbox 134 (FIG. 2), which input shaft would then have corresponding outer splines. Still, in the illustrated example, the support shaft 240 is inserted over the input shaft, the right side being the point of entry, and the driven pulley 200 is pushed over the input shaft until it is fully seated. The free end of the input shaft will then be located on the left-hand side of the machined section inside the support shaft 240 in FIG. 7. A blocking member can then be inserted through the remaining left end to lock the driven pulley 200 in place. Other configurations and arrangements are possible. Among other things, all components or at least one of the components can be mounted directly to the input shaft of the gearbox 134. Still, the driven pulley 200 can be installed on a shaft that is not a gearbox. Other variants are possible as well.

A biasing element 250 is provided between the movable sheave 214 and the support 220. This biasing element 250 can be, for instance, a helical compression/torsion spring. The biasing element urges the movable sheave 214 towards the fixed sheave 210. Other configurations and arrangements are possible. For instance, the biasing element can be formed by more than one spring and/or by other kinds of springs. Other variants are possible as well.

The driven pulley 200 has a direct torque-transmitting engagement between the two sheaves 210, 214 but it is still possible for the mobile sheave 214 to move in the axial direction relative to the fixed sheave 210. This driven pulley 200 thus has a full-torque configuration. The parts creating this feature are located within a relatively small annular space between the support shaft 240 and a bottom of the belt-receiving groove 218. Among other things, the cam surfaces 222, 224 and the followers 230, 232 are located behind the rear side of the movable sheave 214 and they do not retrieve space below the belt-receiving groove 218.

In the illustrated example, there are three elongated and axially extending members 260 rigidly attached to the movable sheave 214 and projecting from its front side towards the fixed sheave 210. The members 260 can be two or more than three in number. Each member 260 extends across the fixed sheave 210 through a corresponding passageway 262. The members 260 can be added parts rigidly connected to the movable sheave 214 or, as shown, be parts made integral with the movable sheave 214. Other configurations and arrangements are possible as well. For instance, one could provide the members 260 on the fixed sheave 210 and corresponding passageways 262 on the movable sheave 214 in some implementations.

In the illustrated example, the fixed sheave 210 is pivotally mounted directly on the support shaft 240 using one or more bushings 270. The bushings 270 are provided on the interior surface of a central hub 272 partially extending at the rear side of the fixed sheave 210. The central hub 272 is rigidly connected to the fixed sheave 210 using fasteners 274, for instance a plurality of axisymmetric and axially extending screws or bolts. Other configurations and arrangements are possible. For instance, other kinds of fasteners can be used. Other variants are possible as well.

FIG. 7 shows that in the illustrated example, the free end of the central hub 272 abuts against an annular bushing 280, which is itself engaged against a rigid washer 282. The inner rim of the washer 282 fits snugly on the outer surface of the support shaft 240, and an oversized annular end portion 284 prevents it from moving out of the support shaft 240. The forces exerted by the drivebelt 104 on the conical wall 212 of the fixed sheave 210 will prevent it from axially moving along the support shaft 240 towards the opposite end. Other configurations and arrangements are also possible. For instance, the central hub 272 can be made integral with the rest of the fixed sheave 210 in some implementations. The bushings can also be replaced by other elements, for instance bearings or the like. Other variants are possible as well.

In the illustrated example, the movable sheave 214 is pivotally and slidably connected directly on the support shaft 240 using one or more bushings 290. These bushings 290 are provided between the support shaft 240 and the interior of an annular inner portion 292 of the movable sheave 214. Other configurations and arrangements are possible as well.

In the illustrated example, the support 220 on which the cam surfaces 222, 224 are provided is rigidly mounted to the support shaft 240 using an arrangement capable at least of establishing a torque-transmission engagement between them. This may include serrations or other features, such as a key 300 as shown in FIG. 7. The support 220 is also prevented from moving in the axial direction using a retaining ring 302 or the like. The rigid connection is thus achieved using two kinds of connectors. Other configurations and arrangements are possible as well.

FIG. 8 is an isometric view illustrating the front side of the movable sheave 214 in the driven pulley 200 shown in FIG. 3. As can be seen, the members 260 are axisymmetric and have a noncircular cross section. Each member 260 has a substantially flattened U-shaped cross-section, with the open side facing radially outward. The inner wall of each member 260 is curved. The shape of these members 260 is designed to provide an optimum resistance to torque and also to the centrifugal forces when the driven pulley 200 rotates at high speeds. Other configurations and arrangements are possible.

FIG. 9 is an isometric view illustrating the rear side of the fixed sheave 210 in the driven pulley 200 shown in FIG. 3. FIG. 9 shows, among other things, the three axisymmetric passageways 262 of this example. Each passageway 262 provides an opening to accommodate the corresponding member 260. The passageways 262 are immediately adjacent to a central opening 264 and are radially inside the conical wall 212 of the fixed sheave 210. This area can be referred to as an inner radial portion 266. Other configurations and arrangements are possible.

FIGS. 10 and 11 are enlarged isometric views of the central hub 272 of the fixed sheave 210 in the driven pulley 200 shown in FIG. 3.

FIGS. 12 and 13 are isometric views of the fixed sheave 210 and the support shaft 240 in the driven pulley 200 shown in FIG. 3.

Each sheave 210, 214 is generally made of a metallic material and an insert 310 made of another material can be provided at each passageway 262 to simplify the manufacturing process and reduce costs, among other things. With such insert 310, the inner periphery of the passageways 262 and the outer surface of the members 260 do not need to be machined with a high precision to ensure a proper sliding engagement. One of the inserts 310 can be seen, for instance, in FIGS. 6 and 7.

FIG. 14 is an enlarged view of one of the inserts 310 provided in a passageway 262 of the driven pulley 200 shown in FIG. 3. Each insert 310 is designed to be individually affixed, for instance simply by snapping, inside each passageway 262. The illustrated example includes two opposite and parallel side portions 312 that are made integral with one another through a transverse portion 314. The insert 310 is made of a material having a lower coefficient of friction than that of the fixed sheave 210, for instance a plastic material having a good resistance to wear. The inserts 310 could be made by injection molding. In use, at least some of the outer surface of the members 260 will be in a sliding engagement with the inserts 310. The insert 310 can snap-fit into the passageway 262 using side tabs 316. FIG. 15 is an enlarged exploded view showing how an insert 310 can be positioned into a passageway 262 in the illustrated example. Other configurations and arrangements are possible as well. Among other things, the inserts 310 can have a shape different from the one shown and described. The inserts 310 could be made of another material or materials, and other manufacturing methods are possible. The inserts 310 can nevertheless be omitted entirely in some implementations. Other variants are possible as well.

FIGS. 16 and 17 are isometric views of the support 220 in the driven pulley 200 shown in FIG. 3.

FIG. 18 is a side view of the driven pulley 200 shown in FIG. 3, the driven pulley 200 being now at the maximum ratio position. This is, for instance, the position at the maximum speed of the vehicle. FIG. 19 is a cross-section view of the driven pulley 200 shown in FIG. 18.

FIGS. 20 and 21 are isometric views similar to FIGS. 3 and 5 but showing a variant of the driven pulley 200 as improved where the central hub is made integral with the rest of the fixed sheave 210. FIG. 22 is a cross-section view of the driven pulley 200 shown in FIGS. 20 and 21.

FIG. 23 is a cross-section view of a variant of the driven pulley 200 as improved. In FIG. 23, the fixed sheave 210 is supported on the support shaft 240 using two bearings 320, 322. The bearing 320 is a thrust bearing. Variants are possible as well.

FIG. 24 is a cross-section view of another variant of the driven pulley 200 as improved. In FIG. 24, each axially extending member 260 has a circular cross-section, namely elongated rods. These rods are also parts added to the movable sheave 214. They can be inserted in corresponding holes by interference. Other kinds of attachments are possible as well.

FIG. 25 is a cross-section view of a CVT 400 incorporating an example of a known driven pulley. This CVT 400 includes a driving pulley 402, a drivebelt 404 and a driven pulley 406.

FIG. 26 is a semi-schematic top view illustrating the CVT of FIG. 25 installed in the same generic vehicle as in FIG. 2. As can be seen, the improved driven pulley 200 requires less space at the left thereof than that of the driven pulley 406. This space saving using the improved driven pulley 200 can be important in some vehicle designs.

FIGS. 27 and 28 are cross-section views provided for dimensional comparisons between the driven pulleys 406, 200 in FIGS. 1 and 25. As can be seen, although they have an identical outer diameter, the range of winding diameters on the improved driven pulley 200 is increased by the distance A compared to that of the known driven pulley 406. The width of the parts extending beyond the left side of the fixed sheave is also notably smaller, the distance C being only a fraction of the distance B.

The present detailed description and the appended figures are meant to be exemplary only, and a skilled person will recognize that many changes can be made while still remaining within the proposed concept. Among other things, and unless otherwise explicitly specified, none of the elements, characteristics or features, or any combination thereof, should be interpreted as being necessarily essential simply because of their presence in one or more examples described, shown and/or suggested herein.

REFERENCE NUMERALS

100 continuously variable transmission (CVT)

102 driving pulley

104 drivebelt

110 fixed sheave (of driving pulley)

112 movable sheave (of driving pulley)

114 support shaft (of driving pulley)

116 centrifugal mechanism (of driving pulley)

118 return spring (of driving pulley)

120 bearing arrangement

130 generi c vehi cl e

132 engine

134 gearbox

136 driveshaft

200 driven pulley

210 fixed sheave

212 conical wall (of fixed sheave)

214 movable sheave

216 conical wall (of movable sheave)

218 drivebelt-receiving groove

220 first support

222 first cam surface 224 second cam surface

230 first follower

232 second cam follower

234 clamp

236 fastener

240 support shaft

242 internal splines

250 biasing element

260 axially extending member

262 passageway (in the fixed sheave)

264 central opening (of fixed sheave)

266 inner radial portion (of fixed sheave)

270 bushing (for fixed sheave)

272 hub

274 fastener

280 annular bushing

282 washer

284 oversized annular end portion

290 bushing (of movable sheave)

292 annular inner portion (of movable sheave)

300 key

302 retaining ring

310 insert

312 side portion (of insert)

314 transverse portion (of insert)

316 side tab (of insert)

320 bearing

322 bearing

400 continuously variable transmission (CVT) 402 driving pulley (of CVT 400)

404 drivebelt (of CVT 400)

406 driven pulley (of CVT 400)