Patent Description:
Continuously variable transmission devices are known in the art. For example, on one example type of such variable transmission devices, planetary members are provided in rolling contact with inner and outer races as described in <CIT> and <CIT>, assigned to the present assignee. The inner and outer races have two parts, with axial separation which is adjustable. The transmission ratio of input to output speed of the device is adjusted by varying the axial separation of the inner or outer race structures, which causes a corresponding radial shift of the planetary members. The axial separation of the corresponding outer or inner race structures adjusts to compensate for the radial change in position of the planetary members. The changing position of the contact points between the planetary members and the inner and outer races causes the change in transmission ratio of the device. Typically, the inner race is coupled with an input shaft and the planetary members are coupled via a planet follower arrangement to an output shaft. However, one or more input shafts and one or more output shafts may be coupled to the inner races, the outer races, or the planet follower arrangement in a variety of configurations. Application of force via springs, electric drive motor, hydraulic displacement or other mechanically driven movement are examples of methods of varying axial separation of either the inner or outer races. Such variation of axial separation shifts the continuously variable transmission. <CIT>) discloses a continuously variable transmission in the general field of the invention.

It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the Figures have not necessarily been drawn to scale. Reference numerals are used to identify the same or analogous components in the Figures where reasonable. Embodiments incorporating teachings of the present invention are shown and described with respect to the drawings presented herein, in which:.

The following description in combination with the Figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings may be utilized in this application, as well as in other applications and with several different types of interconnections of elements within the transmission systems and components disclosed.

The continuously variable transmission (CVT) mechanisms of several embodiments of the invention are formed as variable radius epicyclical mechanisms having rolling traction torque transfer. According to one aspect of the present invention, a continuously variable transmission device of the type having planetary members in rolling contact with radially inner and outer races each comprising two axially spaced parts or race structures is provided. For clarification, rolling contact is intended to mean contact that is not fixed. For example, planetary members may be in contact with race structures during operation of the CVT and roll along race structures. In another example, planetary members may be in rolling contact in some instances even though clamped by race structures during operation. In yet other instances, rolling contact may include a planetary member able to roll, but not rolling, such as when the CVT is at rest. The CVT includes a control system for selectively varying the axial separation of the two race structures of one race and thus the radial position of the planetary members in rolling contact with that race, and in which there is a system sensitive to the torque applied to a drive-transmitting member of the transmission operable to determine the compensating variation in the separation of the two race structures of the other race. This torque sensitive compensating variation determines, along with the varied axial separation of the other race, the transmission ratio of the device which in turn determines to vary the forces exchanged between the planets and the races.

In an embodiment of the CVT structure, the inner and outer races include two radially inner race structures and two radially outer race structures respectively. The two race structures of the inner and outer races may be supported in such a way as to be relatively displaceable towards or away from one another. This axial movement may vary the radius of the point of contact between each race and the planetary members.

Shifting of the continuously variable transmission may occur via control system adjustment to the axial separation of either the radially inner race structures or the radially outer race structures creating a corresponding reaction in the opposite race via the rolling planetary members and their rolling contact with arcuate surfaces of the inner and outer races. Shifting may be done via hydraulic actuation of a hydraulic cavity formed as part of the inner or outer race structures, may be done with mechanical means for actuating inner or outer race structures of the inner or outer races, or may be done via other means known in the art and described in further detail in the related applications or other patents disclosed. In other embodiments, inner and outer races do not necessarily need to be arcuate. The rolling contact surface of inner or outer races may be planar or of another shape in various embodiments but still function in accordance with disclosures herein.

Axial separation of the opposite race structures to the shifted inner or outer races may be adjusted with a reactive force via several possible methods. A spring may apply force to spline-coupled inner or outer race structures. In other embodiments, an inclined plane such as a helical interengagement coupling on the input shaft or to a CVT housing or output shaft, may be used so that rotation of the input shaft in the intended direction causes the two structures of the reactive inner or outer race to approach each other until the force exerted on the inclined plane between the race and the input or output shaft matches the reaction forces between the race and the planetary members. In some examples a ball ramp or roller ramp may act as an inclined plane and couple an inner race or outer race structure with a CVT structure to cause force to be exerted to urge two structures of an inner or outer race to approach one another until a reactive force is matching. The inclined plane structure need not necessarily be planar, but in some embodiments may be of variable pitch or slope depending upon the desired performance characteristics. In some aspects of the present invention, the inclined plane structure may be substantially planar while in other aspects it may be of variable pitch or slope. Inclined plane structure is intended to cover a variety of structures that operate as described herein during matching of approach force for opposite race structures and reactive force between the race and the planetary members. When the urging and reactive forces match, no further relative axial displacement of the inner race structures or outer race structures takes place and a drive torque is transmitted at the transmission ratio determined by the radial position of the planetary members. Although this arrangement enables drive torque to be transmitted between the input and output shaft at the appropriate transmission ratio, undesirable consequences can occur. For example, some of these consequences may occur upon a change in torque direction of the input or output shaft which may cause poor performance or even damage to the CVT. The disclosures of <CIT>) are relevant to the present application. Accordingly, it is desired to provide an improved variable transmission device.

According to an aspect of the present invention, the continuously variable transmission device described herein enables transmission of torque from an input to an output shaft and can take place in either direction of rotation. A continuously variable transmission according to embodiments herein includes planetary members in rolling contact with radially inner and outer races each comprising two axially spaced parts, with control systems for selectively varying the axial separation of the two race structures of one race and thus the radial position of the planetary members in rolling contact with that race. Additionally, according to aspects of several embodiments, there are torque sensitive couplings or a torque sensitive mechanism reactive to the torque applied to a drive-transmitting member of the transmission device. In example embodiments, a torque-sensitive mechanical coupling is interposed between an input drive member, such as a drive shaft, and one of the races (e.g., inner or outer) to balance the torque transmission from the drive member and the contact pressures between the two race structures and the planetary members. For example, an inclined plane structure coupled to the race of the input drive member provides for compensating variation in the axial separation of the two race structures of the opposite race. In another example, the said torque-sensitive coupling includes that of the two axially spaced, relatively moveable race structures of the opposite race, such as that of an output member or fixed to a CVT housing. Each race structure itself be axially movable in two directional senses from a central position and engageable by a limit stop structure to allow the transmission of rotary drive from a rotary drive input such as a drive shaft to a rotary drive output shaft of the transmission device in each of two opposite senses of rotation. In one example, a radially symmetric inclined plane includes a ball ramp or roller ramp between a race structure splined to a drive shaft and a limit stop structure.

In another aspect, the race structures of the torque-sensitive coupling are connected with the input drive member such as a drive shaft by a screw-thread engagement. The torque-sensitive coupling may be included with either side race structure or included on both race structures for a race. If operatively coupled to both race structures, the screw-thread engagement on the drive shaft may be of the opposite hand for each side of the race to urge axial displacement depending on the rotary drive direction transmitted. In one embodiment, the thread flights of the screw thread engagement may be interengaged by rolling elements such as balls to form a ball screw to reduce frictional resistance in the device.

In an embodiment, the two race structures may ultimately be restrained from axial movement such that they are limited in action exerted on it by the input member. A limit stop structure may limit axial movement and may comprise respective abutments on or carried by or associated with the said input drive member or on a CVT housing.

In several embodiments, one or both races may be fully rotational, or rotationally constrained to an input or output drive member such as a shaft. In other embodiments, either race may be rotatably fixed, including being limited in rotational movement, e.g., by a torque-sensitive coupling. In example embodiments, the two race structures of a race of the transmission device may be carried on a housing of the transmission device in such a way as to have a limited rotational displacement in each of two opposite rotational senses. In other words, they may be non-rotatable having little or no rotation except for inclined plane or helical interengagement with the torque sensitive coupling. The relative axial separation of the two race structures of a race may be achieved by an inclined interengagement of at least one of the two race structures with a fixed member of the transmission device, the two race structures both having limited rotation with respect to the said fixed member.

In view of the various possible configurations including a torque sensitive device whereby either the inner or outer race, or both, may be fully rotational and operatively coupled to either an input or an output shaft, operational situations may arise whereby there is a torque transition. The torque transition may take place via the input shaft and may be operationally transferred to the output shaft via one or more CVT components. As discussed above, one or more input shafts may be operatively coupled to any of the inner race, outer race, or planet follower members in various aspects. Additionally, one or more output shafts may be operatively coupled to any of the inner race, outer race, or planet follower members although not to the same as the input shaft. In yet other aspects, any of the inner race, outer race, or planet follower members may be rotatably fixed as discussed above.

A torque transition may take place in the form of a torque impulse to increase or decrease torque applied in an angular displacement direction of an already rotating input or output shaft. This may cause a transition amplitude during the increase or decrease change in torque applied. In some aspects, a torque impulse may take place as a reversal of angular displacement direction of rotation for either an input or output shaft. Such a change is a torque reversal. In any case, as a torque impulse is passed though the CVT components, especially a reversing torque transition, it may cause a transition amplitude and backlash which may result in wear or damage to components of the CVT in certain aspects. In the case of a torque reversal for example, a transition deadband and backlash may be experienced.

The CVT described above uses a reactive clamping mechanism that provides axial load in proportion to torque applied via an input shaft. This reactive clamping mechanism is supplied by the torque-sensitive mechanism or coupling described above. This same torque-sensitive mechanism also may allow for axial displacement between raceway members. In an example mechanism, a ball ramp or a roller ramp may be the torque sensitive mechanism. The ball ramp or roller ramp is radially symmetric, this allows for identical operation independent of torque direction. One of the consequences of having a reactive clamping mechanism that can accommodate reverse torque and axial displacement is backlash. While transition amplitude or backlash elimination may be difficult in certain CVT configurations, it can be managed as described in several embodiments herein.

In previous designs, very little torque resistance existed when taking up the backlash during a reversing torque transition. As a result, the speed of the driving member of the torque, e.g., the input shaft or output shaft, and the race to which it is coupled is allowed to accelerate during a torque reversal. This acceleration occurs until the backlash is taken up in the torque sensitive mechanism. This may result in large torque spikes in the components of the CVT. To better manage this, a torsion damping mechanism is implemented to apply torque resistance to the race coupled to the input or output shaft to mitigate transmitting the torque transition. In an example embodiment, a working spring or other damper may be added and operatively coupled to the race. In example embodiments, the torsion damping mechanism may be implemented as an increased preload spring with stiffer torsional resistance than would be used by those of ordinary skill in the art or a separate torsional damping mechanism, such as a spring causing torsional resistance, may be implemented. In some aspects, adding a separate torsion damping mechanism may add complexity but may be desirable in some designs.

The torsion damping mechanism applies torque between a torque applying member such as an input shaft and an inner or outer race. The torsion damping mechanism permits angular displacement greater than the typical rotation of any torque sensitive inclined plane mechanism operatively coupled in the CVT. For example, the torsion damping mechanism applies torque in an embodiment to permit angular displacement between the torque input such as an input or output shaft and a race of greater than <NUM> degrees. In some embodiments, angular displacement above <NUM> degrees is permitted with application of angular displacement torque from the torsion damping mechanism. The added torsional resistance of the torsion damping mechanism on the race limits backlash, and may overcome any disadvantage of the added force required to shift the transmission, or of loss due to added friction. In an embodiment, torsion damping mechanisms may be operatively coupled to either side or both sides of an inner or outer race. The torsion damping mechanisms may be oppositely axially resiliently biased. The opposite axial bias of the torsion damping mechanism may "prime" the torque-sensing reaction. Torque resistance may be achieved by torsion damping mechanisms such as a compression spring, torque spring, flat spring, coil spring, or other damping mechanism operable to apply angular torque force sufficient for torque resistance to prime a torque sensing reaction in the torque-sensitive mechanism of a CVT. In an example embodiment, the torsion damping mechanism used may apply a medium force that is a choice between a force that is so high it causes highly detrimental effects on shifting or one that is too low to mitigate backlash during torsional transition. The force levels are discussed further below.

In yet another aspect, two race structures forming an inner race or an outer race are rotationally constrained to one another to form a type of race assembly according to other embodiments of the present invention. The race structures may also be rotationally constrained with respect to a rotating input or output shaft or an inclined plane structure operatively coupled to a housing. For example, if an outer race is part of a hydraulic outer race assembly similar to embodiments in the above related applications, it is possible that the rolling planetary members may float axially with respect to the outer race assembly. In an embodiment, the radially inner race structures, each with an arcuate rolling contact surface, are rotationally constrained with respect to one another and must rotate in symmetry. Since the radially inner race structures may also be rotationally constrained with respect to an input or output shaft via helical inter-engagement or other inclined plane engagement, the radially inner race structures may maintain symmetry and limit or eliminate axial "float" of the rolling planetary members. The reverse arrangement is also contemplated wherein the radially inner race structures are part of a hydraulic inner race assembly in other embodiments. In this case, the radially outer race structures may be rotationally constrained to one another and to an inclined plane structure that is fixed or coupled to a rotating input or output shaft. In addition, rotationally constraining opposite race structures to one another may permit a torsion damping mechanism to be used in connection to one side of the race and use of a torsion damping mechanism on both sides may not be necessary.

<FIG> shows a continuously variable transmission (CVT) in example embodiment not forming part of the present invention. In the example embodiment, the CVT is a variable radius epicyclical transmission device. The CVT shown depicts a housing <NUM> within which is mounted an sun shaft <NUM>, and rolling element bearings <NUM>, <NUM> within a planet carrier <NUM> carrying three planet follower members <NUM>. The planet follower members <NUM> are rotatably borne on the planet carrier <NUM> by planet follower shafts <NUM>. Any number of planet follower members <NUM> are contemplated and may depend on the number of spherical planetary members <NUM>. The spherical planetary members <NUM> are substantially spherical as described below and captive between the radially inner races <NUM> and the radially outer races <NUM>. The planet follower members <NUM> are circumferentially intercalated between adjacent pairs of spherical planetary members <NUM> for transmitting drive to or from the said spherical planetary members <NUM>. In an embodiment, planet follower members <NUM> are carried on planet carrier <NUM> by planet follower shafts <NUM> which transmit drive to or from spherical planetary members <NUM> in operation of the CVT device.

The planet carrier <NUM> is effectively coupled to axial cylindrical extension <NUM> of the planet carrier <NUM> and may comprise an output in one embodiment. Planet carrier <NUM> may be further coupled to output shaft <NUM> of the transmission mechanism via the extensions <NUM>. It is understood that the input and output relationship described above may also be reversed in other embodiments. Alternatively, the input and output shafts may be coupled to any of the inner race <NUM>, the planet carrier <NUM>, or the outer race <NUM> in various embodiments.

In an embodiment, sun shaft <NUM> may carry a radially inner race <NUM> comprising a sun member including two structures <NUM>a, <NUM>b which are engaged to the shaft <NUM>. Sun shaft <NUM> may also be referred to as a sun shaft <NUM> in some embodiments or an output shaft <NUM> in other embodiments depending upon the arrangement. Radially inner race <NUM> may be coupled to the input shaft via a coupling comprising a spline or other coupling including torque sensitive inclined plane structures <NUM>a and <NUM>b such as roller ramps or ball ramps or other structures understood in the art. Further, inclined plane structures need not be planer, but may be of variable pitch or slope as described above.

In an embodiment, the torque sensitive inclined plane structures <NUM>a and 63b are torque sensitive in a plurality of angular displacement directions. The torque sensitive inclined plane structures <NUM>a and <NUM>b may accommodate torque applied to the system via either shaft <NUM> or <NUM> in either torque direction.

In one embodiment, radially inner race structures <NUM>a and <NUM>b are coupled to sun shaft <NUM> via a spline. Radially inner race structures <NUM>a and <NUM>b are axially movable along the axis of rotation of the sun shaft <NUM>. Inward axial movement may be urged by a mechanical, electromechanical, or hydraulic mechanism as described in various embodiments. In the presently shown embodiment, springs <NUM> are used to apply a preload force to urge axial movement of radially inner race structures <NUM>a and <NUM>b for clamping of the inner race <NUM> to the spherical planetary members <NUM>. Additionally, one or more torsion damping mechanisms <NUM> are coupled to the radially inner race structures <NUM>a and <NUM>b to apply a priming torque to inner race <NUM> or torque sensitive inclined plane structures <NUM>a and <NUM>b. Other couplings to the sun shaft <NUM> are also contemplated. Torsion damping mechanisms <NUM> in the shown embodiment are disk springs to apply a resilient bias to "prime" the torque-sensing reaction of the device, for example, during an impulse in a torque transition, such as a reversal in torque on sun shaft <NUM> or shaft <NUM>. In the presently shown embodiment, sun shaft <NUM> acts as an input shaft and shaft <NUM> is an output shaft, but the input-output relationship may be reversed in this and other embodiments depending on configuration as is understood. Additionally, the torsion damping mechanism <NUM> may be operatively coupled to one or more radially inner race structures <NUM>a and <NUM>b via other structures. For example, in the presently shown embodiment, the torsion damping mechanism is operatively coupled to the radially inner race structures <NUM>a and <NUM>b via one or more torque sensitive inclined plane structures <NUM>a and <NUM>b. In an embodiment, the torque sensitive inclined plane structures <NUM>a and <NUM>b may be oppositely axially resiliently biased.

Spherical planetary members <NUM> are engaged between the radially inner race <NUM> and a radially outer race <NUM>. Radially outer race <NUM> also comprises two axially separated annular race structures <NUM>a, <NUM>b. Rolling contact surfaces of the race structures <NUM>a, <NUM>b and <NUM>a, 26b, respectively identified as <NUM>a, 27b and <NUM>a, <NUM>b each include, in cross-section, an arcuate surface the radius of which is slightly greater than the radius of the spherical planetary members <NUM>. Hereinafter, spherical planetary members include planetary members that are substantially spherical bodies or have surfaces of revolution that are spherical or substantially spherical. Substantially spherical as is understood may include right circular, oblate or prolate spheroids or other structures capable of symmetrical revolution. Alternatively, the planetary members may have respective first and second surface portions comprising surfaces of revolution about the same axis (for each member) the surface portions being inclined with respect to one another in opposite directions about the axes of revolution and only the surface portions of the planetary member in rolling contact with inner or outer races being substantially spherical. The spherical planetary members may have a convex or concave surface of revolution defined by a curved generatrix which may be a regular or irregular curve or a part-circular curve. In the case of a part-circular generatrix this may be a semi-circle, in which case the surface of revolution of the planetary member is substantially spherical.

Axial adjustment mechanisms may be made via hydraulic systems as described in related applications cited herein or in different embodiments may include a mechanical system such as a lever or arm, screw mechanism, and electromechanical mechanism or other mechanism to axially adjust the distance between radially outer race structures <NUM>a, <NUM>b. In other embodiments, axial adjustment mechanisms may be used to axially adjust the distance between radially inner race structures <NUM>a, <NUM>b (not shown).

In operation of shaft <NUM>, as an input shaft in one embodiment, torque from shaft <NUM> causes rotation and the transmission rotation of the shaft <NUM> is transmitted to the inner race <NUM>, rotation of which causes rotation of the spherical planetary members <NUM> by rolling contact. The spherical planetary members <NUM> are in rolling contact with outer race <NUM>. In one embodiment, outer race <NUM> may rotate and connect to another output shaft. In other embodiments, outer race <NUM> may be non-rotating.

Rotation of the spherical planetary members <NUM> is transmitted via the planet followers <NUM> to the planet carriers <NUM> and thus to the output shaft <NUM>. Spherical planetary members <NUM> are also in rolling contact with outer race <NUM>. Shifting may occur by mechanical, hydraulic or other actuation of two radially outer race structures <NUM>a, <NUM>b of the outer race <NUM>. Upon actuation, the two radially outer race structures <NUM>a, <NUM>b are urged towards one another or allowed to move axially away from one another respectively. Axial approach of the two radially outer race structures <NUM>a, <NUM>b applies pressure to the spherical planetary members <NUM> causing the spherical planetary members <NUM> to move radially inwardly and urge the two radially inner race structures <NUM>a, <NUM>b apart. In an embodiment, a torque sensitive inclined plane structure <NUM>a, <NUM>b between the radially inner race structures <NUM>a, <NUM>b and the shaft <NUM> acts in effect as a torque-sensitive mechanism such that rotation of the shaft <NUM> in the intended direction of drive causes the race structures <NUM>a, <NUM>b to approach one another axially when resisted by drag so that any play in the rolling contact between the races and the spherical planetary members <NUM> is taken up and compensated by the tendency of the race structures <NUM>a, <NUM>b to approach one another until the forces exerted on the helical interengagement between the race structures <NUM>a, <NUM>b and the drive shaft <NUM> matches the reaction forces between the race structures <NUM>a, <NUM>b and the spherical planetary members <NUM>. At this point no further relative axial displacement of the race structures <NUM>a, <NUM>b takes place and drive transmission takes place at a transmission ratio determined by the radial position of the spherical planetary members <NUM> when this occurs.

The torque sensitive inclined plane structures <NUM>a, <NUM>b may be radially symmetric such as roller ramps or ball ramps. Radial symmetry of a torque sensitive inclined plane structures <NUM>a, <NUM>b allow for identical torque sensitive clamping independent of torque direction. During a change in torque, the torque sensitive inclined plane structures <NUM>a, <NUM>b provide a proportional axial load on the system. In the present embodiment of <FIG>, the torque sensitive inclined plane structures <NUM>a, <NUM>b are operatively connected to the radially inner race <NUM> and to shaft <NUM>. In other embodiments, the torque sensitive inclined plane structures <NUM>a, <NUM>b may be in other locations and serve the same purpose of providing proportional axial load on the system in reaction to applied torque. For example, the torque sensitive inclined plane structures <NUM>a, <NUM>b may be operatively connected to the radially outer race <NUM> and the housing <NUM>. In yet other embodiments, the torque sensitive inclined plane structures <NUM>a, <NUM>b may be operatively connected to the planet carriers <NUM> or other rotating structures.

During a torque reversal on sun shaft <NUM> or on output shaft <NUM>, the radially symmetric torque sensitive inclined plane structures <NUM>a, <NUM>b reverse to provide proportional axial movement in response to the reverse torque direction as well. However, as a torque transition to the reverse torque direction occurs in the CVTs of the presently described embodiments, a backlash or torque spike may occur. This happens as the radially symmetric torque sensitive inclined plane structures <NUM>a, <NUM>b reach the bottom part or trough of the inclined plane before proceeding up the reverse inclined plane to provide proportional axial movement to the system. At the bottom or trough of the torque sensitive inclined plane structures <NUM>a, <NUM>b there is very little resistance to the torque transition.

The backlash or torque spike during such a torque transition may cause a jarring or slamming of the rotating components in the CVTs of the present invention depending on the severity of the backlash. This can precipitate damage or excessive wear of components. While backlash is difficult to eliminate, it may be better managed. Application of a priming torque via torsion damping mechanisms <NUM> to the torque sensitive inclined plane structures <NUM>a, <NUM>b may provide for reduction of the backlash or torque spike during torque transition. As described, torsion damping mechanisms <NUM> may be a torsion spring, disk spring or other structure to apply a priming torque to the torque sensitive inclined plane structures <NUM>a, <NUM>b or other rotating structures to mitigate the backlash or torque spike during torque transition. In other embodiments as described below, the preload spring may be increased in applied torsional force to also serve to act as a torsion damping mechanism <NUM>. The preload spring, therefore, may be simultaneously used to apply a torque preload during torque transition.

The force applied via the torsion damping mechanisms <NUM> is substantially higher than the amount for preloading in previous embodiments of the CVTs of the present invention. During testing, it was found that currently used preload springs made effectively no contribution to torsion damping during torque transition although preload force was sufficient for operation of the epicyclical CVTs of the present invention. Additional torsional spring force application via the torsion damping mechanisms <NUM> is counterintuitive due to the increased friction and power loss due to over clamping in the operation of the epicyclical CVT of the current invention, for example during light drive torque operation. Similarly, it is counterintuitive because the added torsional spring force of the torsion damping mechanisms <NUM> requires additional force for shifting the CVT. Nonetheless, the additional of torsion damping mechanisms <NUM>, or an increased preload spring acting as a torsion damping mechanism, discussed further below, yields substantial benefit in reduction of backlash during torque transition.

In an embodiment, the torsion damping mechanisms <NUM> were Belleville springs or disk spring stacks. Each disk spring may provide certain spring rating depending on dimensions, thickness, and material type. Additionally, spring force may be controlled depending on stacking of the disk springs, either with arced disk structure nested or opposing to provide varying spring force and compression travel dimensions. The disk springs or Belleville springs have an added benefit of having high load density enabling a reduction of package volume for the epicyclical CVT structures in the present invention. Too much torsional or axial force applied via the torsion damping mechanisms <NUM>, however, was detrimental to the efficient operation of the epicyclical CVTs of the present invention. For example, if a spring set used as torsion damping mechanisms <NUM> were too heavy, it could limit shifting ratios available including axial travel of the radially inner race structures <NUM>a and <NUM>b. If the spring set used as torsion damping mechanisms <NUM> were too light, and no additional preload spring is used to maintain traction during torque impulses, such as torque reversals, the system may be prone to gross slipping and corresponding lost torque transmission. Selection of the spring set used as torsion damping mechanisms <NUM> will depend on several factors including dimensions of the epicyclical CVT, the torque levels applied through the system, and the speeds of rotation during operation of the CVTs among other factors. Moreover, the beneficial effects of the torsion damping mechanisms <NUM> will also depend on the expected characteristics of the torque transition. For example, amplitude (e.g., N*m) of the torque transition or the time interval or speed of the torque transition have direct effects on the magnitude of the backlash or torque spike experienced by the system. Thus, design tradeoffs may be made about the level of spring set used as torsion damping mechanisms <NUM> depending on expected aspects of torque transitions and dimensions and operating characteristics of the epicyclical CVT.

<FIG> shows a continuously variable transmission (CVT) in another example embodiment not forming part of the present invention. In the example embodiment, the CVT is a variable radius epicyclical transmission device. The CVT shown depicts a housing <NUM> within which is mounted on a sun shaft <NUM>, and rolling element bearings <NUM>, <NUM> within a planet carrier <NUM> carrying three planet follower members <NUM>. The planet follower members <NUM> are rotatably borne on the planet carrier <NUM> by planet follower shafts <NUM>. Any number of planet follower members <NUM> are contemplated and may depend on the number of spherical planetary members <NUM>. The spherical planetary members <NUM> are substantially spherical as described below and captive between the radially inner races <NUM> and the radially outer races <NUM>. The planet follower members <NUM> are circumferentially intercalated between adjacent pairs of spherical planetary members <NUM> for transmitting drive to or from the said spherical planetary members <NUM>. In an embodiment, planet follower members <NUM> are carried on planet carrier <NUM> by planet follower shafts <NUM> which transmit drive to or from spherical planetary members <NUM> in operation of the CVT device.

In an embodiment, the planet carrier <NUM> may be effectively comprised by two radial plates <NUM>a, <NUM>b joined together by shouldered studs <NUM> forming the planet follower shafts. An axial cylindrical extension <NUM> of the radial plate 14b of the planet carrier <NUM> comprises an output and may be further coupled to the output shaft <NUM> of the transmission mechanism. It is understood that the input and output relationship described above may also be reversed in other embodiments. In other words, shaft <NUM> may be an input shaft and sun shaft <NUM> may be an output shaft. It is also understood that in other embodiments, an input or output shaft may couple to radially outer race <NUM> if radially outer race <NUM>, or some portion thereof, is rotatable and arranged to transmit rotation to or from the epicyclical CVT. In yet other embodiments, a plurality of input or output shafts is contemplated being coupled to rotating components of the CVT.

In a current embodiment, sun shaft <NUM> may carry a radially inner race <NUM> comprising a sun member including two structures <NUM>a, <NUM>b which are engaged to the shaft <NUM>. Radially inner race <NUM> may be coupled to the sun shaft <NUM> via a coupling comprising a spline or other coupling including a torque sensitive inclined plane structure such as a helical interengagement in the form of a screw threaded engagement (not shown). In one embodiment, radially inner race structures <NUM>a and <NUM>b are coupled to sun shaft <NUM> via a spline. Radially inner race structures <NUM>a and <NUM>b are axially movable along the axis of rotation of the sun shaft <NUM>. Inward axial movement may be urged by a mechanical, electromechanical, or hydraulic mechanism as described in embodiments below. In the presently shown embodiment, springs <NUM> are used to apply a preload force to urge axial movement of radially inner race structures <NUM>a and <NUM>b for clamping of the inner race <NUM> to the spherical planetary members <NUM>. Other couplings to the sun shaft <NUM> are also contemplated. In some embodiments, the two radially inner race structures 23a and 23b have torque sensitive inclined plane structures <NUM>a, <NUM>b, such as a ball ramp or roller ramp for reasons which are described in more detail above, in the related applications, and in <CIT>. A relative rotation of the sun shaft <NUM> and the radially inner race structures <NUM>a, <NUM>b in one directional sense will cause the two race structures to be displaced towards one another whereas axial separation of the two race structures <NUM>a, <NUM>b of the inner raceway occurs where there is relative rotation between them and the sun shaft <NUM> in the opposite directional sense.

Preload springs <NUM> may also act as torsion damping mechanisms. Preload springs <NUM> may provide a priming torque force and act as a torsion damping mechanisms during torque transitions on shaft <NUM> or <NUM>, depending upon configuration. In this embodiment, preload spring <NUM> are also torsion damping mechanisms <NUM> and provide both torque priming in addition to providing a preload force described herein. For example, preload springs <NUM> may be heavy enough to behave similarly to the torsion damping mechanisms <NUM> of <FIG>. Operation of the dual purpose springs <NUM> will be similar to the torsion damping mechanisms <NUM> described in <FIG> above to reduce or mitigate backlash or torque spikes during torque transitions such as during torque reversals. Selection of a spring set <NUM> that is too heavy may have overly detrimental effects such as over clamping or increased shifting force requirements as described above. If spring set <NUM> is too light, slippage is possible due to insufficient resistance during the torque transition.

In the CVT embodiment of <FIG>, spherical planetary members <NUM> are engaged between the radially inner race <NUM> and a radially outer race <NUM>. Radially outer race <NUM> also comprises two axially separated annular race structures <NUM>a, <NUM>b. Rolling contact surfaces of the race structures <NUM>a, <NUM>b and <NUM>a, <NUM>b, respectively identified as <NUM>a, <NUM>b and <NUM>a, <NUM>b each include, in cross-section, an arcuate surface the radius of which is slightly greater than the radius of the spherical planetary members <NUM>. Hereinafter, spherical planetary members include planetary members that are substantially spherical bodies or have surfaces of revolution that are spherical or substantially spherical. Substantially spherical as is understood may include right circular, oblate or prolate spheroids or other structures capable of symmetrical revolution. Alternatively, the planetary members may have respective first and second surface portions comprising surfaces of revolution about the same axis (for each member) the surface portions being inclined with respect to one another in opposite directions about the axes of revolution and only the surface portions of the planetary member in rolling contact with inner or outer races being substantially spherical. The spherical planetary members may have a convex or concave surface of revolution defined by a curved generatrix which may be a regular or irregular curve or a part-circular curve. In the case of a part-circular generatrix this may be a semi-circle, in which case the surface of revolution of the planetary member is substantially spherical.

The radially outer race structures <NUM>a, <NUM>b are coupled to housing <NUM> via hydraulic cavity <NUM> which may act as an axial adjustment mechanism via hydraulic displacement in an embodiment as described above, in the incorporated related applications. Additional shifting mechanisms, such as mechanical or electromechanical shifting systems are contemplated in addition to hydraulic shifting of the present embodiment. For example, other axial adjustment mechanisms are also contemplated in different embodiments including a mechanical system such as a lever or arm, screw mechanism, and electromechanical mechanism or other mechanism to axially adjust the distance between radially outer race structures <NUM>a, <NUM>b. In other embodiments, hydraulic cavity <NUM> may be formed between radially outer race structures <NUM>a, <NUM>b and an outer race hydraulic cavity housing (not shown) located between the radially outer race structures <NUM>a, <NUM>b and housing <NUM>. In one such embodiment therefore, the outer race assembly may be rotatable with respect to an input or output shaft, including radially outer race structures <NUM>a, <NUM>b.

In operation of shaft <NUM>, an input shaft in one embodiment, the transmission rotation of shaft <NUM> is transmitted to the inner race <NUM>, rotation of which causes rotation of the spherical planetary members <NUM> by rolling contact. The spherical planetary members <NUM> are in rolling contact with outer race <NUM>. In one embodiment, outer race <NUM> may rotate and connect to another output shaft. In other embodiments, outer race <NUM> may be non-rotating. Rotation of the spherical planetary members <NUM> is transmitted via the planet followers <NUM> to the planet carrier <NUM> and thus to the output shaft <NUM>. Spherical planetary members <NUM> are also in rolling contact with outer race <NUM>.

By adjusting axial distance between two radially outer race structures <NUM>a, <NUM>b of the outer race by urging towards one another or allowing them to move axially away from one another respectively, shifting of the epicyclical CVT may be achieved. Axial approach of the two radially outer race structures <NUM>a, <NUM>b applies pressure to the spherical planetary members <NUM> causing the spherical planetary members <NUM> to move radially inwardly and urge the two radially inner race structures <NUM>a, <NUM>b apart. In an embodiment, a torque sensitive inclined plane structure <NUM>a, <NUM>a, 63b and <NUM>b, for example a ball ramp shown in the present embodiment, between the radially inner race structures <NUM>a, <NUM>b and the shaft <NUM> acts in effect as a torque-sensitive mechanism in that rotation of the shaft <NUM> in the intended direction of drive causes the race structures <NUM>a, <NUM>b to approach one another axially when resisted by drag so that any play in the rolling contact between the races and the spherical planetary members <NUM> is taken up and compensated by the tendency of the race structures <NUM>a, <NUM>b to approach one another until the forces exerted on the helical interengagement between the race structures <NUM>a, <NUM>b and the drive shaft <NUM> matches the reaction forces between the race structures <NUM>a, 23b and the spherical planetary members <NUM>. At this point no further relative axial displacement of the race structures <NUM>a, <NUM>b takes place and drive transmission takes place at a transmission ratio determined by the radial position of the spherical planetary members <NUM> when this occurs.

During a torque impulse such as a torque reversal, torsion damping mechanisms in the form of springs <NUM> having sufficient torque application may mitigate a torque transition amplitude spike or a backlash. For example, a transition amplitude or backlash deadband may occur during a torque transition in the epicyclical CVT having a radially symmetric torque sensitive inclined plane structure <NUM>a, <NUM>a, <NUM>b and <NUM>b. Upon transition, such as reversal in torque direction, a trough or low point is reached where no resistance or clamping occurs until the torque sensitive inclined plane structure <NUM>a, <NUM>a, <NUM>b and <NUM>b re-engages in the reverse direction. Upon re-engagement, a backlash may be experienced. To avoid this, a priming torque or damping is applied via torsion damping mechanism <NUM> in the present embodiment. This torsion damping mechanism <NUM> applies torque to limit backlash effects of the torque transition experienced with the radially symmetrical torque sensitive inclined plane structure <NUM>a, <NUM>a, <NUM>b and <NUM>b.

<FIG> illustrates effects of a plurality of torsion damping mechanisms on backlash during torque transitions of an epicyclical CVT such as those of the present invention. <FIG> shows a torque reversal data overlay <NUM> for a CVT for four example CVT arrangements. The effects of increased torsional damping and preload may be seen on the torsion spike or backlash effect. As shown, the effect is more pronounced in torque reversal transition from negative torque to positive torque than in the opposite transition in some embodiments. One shown arrangement has little or no torsion damping mechanism, using only a preload spring such as a wave spring. The other overlaid data shows three system arrangements having levels of torsional damping: light, medium, and heavy. The right axis <NUM> shows carrier torque in Nm. The horizontal axis <NUM> shows time during a series of four torque reversals. The torque transition time for these torque reversals is at <NUM> second sweeps. The speed of torque reversal impacts the amplitude of the spikes whereupon faster transitions show higher spikes. The sweeps were transitioned from <NUM> positive torque to -<NUM> torque.

The CVT system tested with only a preload spring shows a very high backlash torque spike <NUM> during transition. In the next torque reversal test, light torsion damping was used in a torsion damping mechanism. In an example embodiment, the arrangement involved stacking six light weight disk springs in series as a torsion damping mechanism. For example, a light weight disk spring may have approximate dimensions of <NUM> x <NUM> x <NUM> x <NUM>. Other dimensions similar to these are contemplated depending on the material used. As can be seen in <FIG>, the backlash spike <NUM> is somewhat reduced.

Overlaid on the data of <FIG> is a third torque reversal test utilizing medium torsion damping. In another embodiment, the arrangement involved stacking four medium weight disk springs as a torsion damping mechanism. For example, a medium weight disk spring may have approximate dimensions of <NUM> x <NUM> x <NUM> x <NUM>. Other dimensions of medium weight springs similar to these are contemplated depending on the material used. As can be seen in <FIG>, the backlash spike <NUM> is substantially reduced. A fourth overlay of <FIG> includes a fourth torque reversal test utilizing heavy torsion damping. In an embodiment, the arrangement involved stacking three heavy weight disk springs in series as a torsion damping mechanism. For example, a heavy weight disk spring may have approximate dimensions of <NUM> x <NUM> x <NUM> x <NUM>. Other dimensions of heavy weight springs similar to these are contemplated depending on the material used. Backlash spike <NUM> reflects a very substantial reduction with heavy torsion damping. However, it was found that at a certain level of torsional damping, drawbacks such as greater force to shift, greater friction, and over clamping as described above could cause impact on CVT performance. In certain embodiments, however, it is contemplated that the above-described potential drawbacks may nonetheless be tolerable depending upon the usage of the CVT. Thus, heavy torsion damping is incorporated as a useful embodiment in the present invention.

<FIG> shows a closer view of a CVT in another example embodiment not forming part of the present invention. As can be seen, radially outer race structures 26a and 26b form outer race <NUM> which may be in rolling contact with spherical planetary member <NUM>. Hydraulic cavity <NUM> is formed between radially outer race structures <NUM>a and <NUM>b and CVT housing <NUM>. In other embodiments, hydraulic cavity <NUM> may be formed between radially outer race structures <NUM>a and <NUM>b and a hydraulic cavity structure such as an outer race hydraulic cavity housing (not shown) separate from the CVT housing <NUM>. Hydraulic ports 34a and 34b permit adjustment to hydraulic pressure in the hydraulic cavity <NUM>. Input or removal of hydraulic fluid may be made via connector port <NUM>. Hydraulic bridge <NUM> may link hydraulic ports 34a and 34b to permit uniform application of hydraulic pressure in hydraulic cavities <NUM> associated with radially outer race structures <NUM>a and 26b in one embodiment. In this way, some uniformity and symmetry may be maintained between radially outer race structures <NUM>a and <NUM>b, especially when positive hydraulic pressure is applied. Nonetheless, it is possible for radially outer race structures <NUM>a and <NUM>b to float or slide to one or the other side causing spherical planetary members <NUM> and inner race <NUM> to also potentially slide. This is addressed more fully below.

Input ports <NUM>a, <NUM>b and hydraulic bridge <NUM> allows for hydraulic fluid connection to the CVT to allow control over hydraulic displacement for radially outer race structures <NUM>a and <NUM>b via the hydraulic cavities <NUM>. Sealing mechanisms <NUM> are used to establish one or more hydraulic cavities between radially outer race structures <NUM>a and <NUM>b and housing <NUM>. In other embodiments, an outer race hydraulic cavity housing or other hydraulic cavity structure may also be fitted with radially outer race structures and be of varied shapes to accommodate a hydraulic cavity. The sealing mechanisms <NUM> may be an o-ring, a sealing layer, or a fluid bearing formed of hydraulic fluid at a junction point or points that are in close proximity between radially outer race structures <NUM>a and <NUM>b and housing <NUM>. Such junction points may be, for example, edges or shoulders of a distal surface of radially outer race structures <NUM>a and <NUM>b and housing <NUM> or other hydraulic cavity structure designed to fit together in close proximity. Corresponding edges or shoulders of an inner surface of housing <NUM> or another hydraulic cavity structure are in close proximity to the edges of shoulders of the distal surface of the radially outer race structures. The sealing mechanisms <NUM> still may permit radially outer race structures 26a and 26b to move axially. In some embodiments, sealing mechanisms <NUM> may permit radially outer race structures 26a and 26b also to rotate about the axis of sun shaft <NUM>.

In the configurations illustrated in <FIG> and <FIG> it will be seen that when the radius of rolling contact between the spherical planetary members <NUM> and the inner race <NUM> is relatively small and the radius of contact between the spherical planetary members <NUM> and the outer race <NUM> is also relatively small, the transmission ratio between the sun shaft <NUM> and output shaft <NUM> is at a low level. By relaxing hydraulic displacement with a negative displacement in hydraulic cavity <NUM>, outer race structures <NUM>a, <NUM>b are allowed to move apart so that the spherical planetary members <NUM> can move radially outwardly as compensated by axial approach of the radially inner race structures <NUM>a, <NUM>b. This increases the transmission ratio between the sun shaft <NUM> and output shaft <NUM>.

By actuating hydraulic displacement in hydraulic cavity <NUM>, outer race structures <NUM>a, <NUM>b are urged to move together so that the spherical planetary members <NUM> can move radially inwardly again as assisted by axial approach of the radially inner race structures <NUM>a, <NUM>b. This again reduces the transmission ratio.

The difference between the curvature of the curved rolling contact surfaces <NUM>a, <NUM>b of radially outer race structures <NUM>a, <NUM>b and curved rolling contact surfaces <NUM>a, <NUM>b of radially inner race structures <NUM>a, <NUM>b of the races <NUM>, <NUM> and the shape of the spherical planetary members <NUM> will determine the precise shape of the contact path which changes in response to transmission ratio changes. Although the contact may be a point contact, in practice, because the interior of such a variable transmission would contain a lubricant in the form of a special traction fluid which both lubricates the moving parts and enhances the rolling traction between them, the points of contact will comprise contact patches which may be larger the closer the radii of the contacting surfaces are to one another.

The continuously variable transmission mechanism described above is extremely compact and highly efficient. A pressurized hydraulic circuit connected to input port <NUM> may be used for control purposes in order to achieve the required function.

<FIG> shows a cross section of radially outer race structures <NUM>a and <NUM>b of one example embodiment of an outer race <NUM>. <FIG> shows a side view of a race structure of outer race <NUM> in accordance to another embodiment of the present invention. Radially outer race structures <NUM>a and <NUM>b are shown and include arcuate rolling contact surfaces <NUM>a and <NUM>b. Sealing mechanisms <NUM> are shown in the present embodiment mounted on a surface opposite to arcuate rolling contact surfaces <NUM>a and <NUM>b and distal to a plane of rotation for the spherical planetary members <NUM>. In this example embodiment, o-ring sealing mechanisms are shown, but several alternate sealing mechanisms are contemplated including example embodiments discussed further above. In other embodiments, sealing mechanisms may be mounted on a housing or other hydraulic cavity structure that is designed to fit with radially outer race structures <NUM>a and <NUM>b to create a hydraulic cavity as described above. In yet another embodiment, sealing mechanisms <NUM> may be mounted on both radially outer race structures <NUM>a and <NUM>b and the housing or other hydraulic cavity structure. And in yet another embodiment, sealing mechanisms may not be mounted but instead be formed between portions of radially outer race structures <NUM>a and <NUM>b in close proximity to portions of a fitted hydraulic cavity structure or housing as with, for example, a fluid bearing.

Those close proximity portions may be designed to fit with corresponding structure of the other part or parts forming a hydraulic cavity. Example of portions of the radially outer race structures <NUM>a and <NUM>b may include an edge or shoulder <NUM> on the distal surface of the radially outer race structures <NUM>a and <NUM>b. The outer surface of radially outer race structures <NUM>a and <NUM>b may be considered in some embodiments to be a surface or surfaces opposite to the arcuate rolling contact surfaces <NUM>a and <NUM>b. Edge <NUM> is designed to nest into a corresponding surface of a housing or other hydraulic cavity structure to establish a hydraulic seal on one side of a hydraulic cavity. A second edge or shoulder <NUM> may be formed to form a second hydraulic seal on another side of the hydraulic cavity. In one embodiment, the second edge <NUM> may be formed of an edge protruding from an outer surface of radially outer race structures <NUM>a and <NUM>b. In an embodiment, second edge <NUM> may be formed as an edge around opening <NUM> through which shaft <NUM>, inner race, planet carrier, planet followers, and other CVT components may fit.

<FIG> shows a side view of a radially outer race structure <NUM>a or <NUM>b. Sealing mechanisms <NUM> are mounted on a first edge or shoulder <NUM> on the distal surface of the radially outer race structure <NUM>a or <NUM>b and a second edge or shoulder <NUM> respectively. Between the sealing mechanisms <NUM> on the first <NUM> and second edge <NUM> is part of the radially outer race structure <NUM>a or <NUM>b forms one side of a hydraulic cavity. Opening <NUM> allows for passage of CVT components such as an input shaft, inner race, planet carrier, and planet followers among other components. Opening <NUM>, and second edge <NUM>, are round in the present embodiment permitting rotation of the CVT components that pass through opening <NUM>. First edge or shoulder <NUM> is of a polygonal shape <NUM> in the present embodiment. The profile polygonal shape <NUM> of first edge <NUM> fits correspondingly with a polygonal shape of a housing of the CVT or an outer race hydraulic cavity housing or other hydraulic cavity structure to form a side of the hydraulic cavity. The profile polygonal shape <NUM> of first edge <NUM> in some embodiments prevents rotation of outer race <NUM> about the axis of rotation of the input shaft. In other embodiments, the profile polygonal shape <NUM> of first edge <NUM> prevents rotation of radially outer race structure <NUM>a or <NUM>b separate from an outer race hydraulic cavity housing or other hydraulic cavity structure. It is understood that any polygon may be used and that partial polygons or shapes with a straight edge or an angle may be used instead to achieve a similar purpose to a polygonal shape. In other embodiments, a spline structure or post structure may be used to hold the radially outer race structure <NUM>a or <NUM>b non-rotationally relative to a hydraulic cavity structure or housing.

Turning back to <FIG>, an embodiment is shown with a sealing mechanism <NUM> mounted in an edge or shoulder <NUM> of housing <NUM> corresponding to first edge <NUM> of radially outer race structure <NUM>a. Another sealing mechanism <NUM> is mounted in an edge or shoulder <NUM> of housing <NUM> corresponding to second edge <NUM> as described above for radially outer race structure <NUM>b. Each hydraulic cavity <NUM> is between radially outer race structure <NUM>a or 26b and housing <NUM> in the embodiment of <FIG>. Profile polygonal shape <NUM> of first edge <NUM> is designed to fit nestingly into housing <NUM> so outer race <NUM> is non-rotatable in this embodiment. In other embodiments, outer race <NUM> may not have a profile polygonal shape, but instead may have a rounded shape to allow rotation of outer race <NUM> and allow coupling to an output or input shaft.

<FIG> also shows detail of inner race <NUM>. Radially inner race structures <NUM>a and <NUM>b are operatively coupled to one or more torque sensitive inclined plane structures. In an embodiment, one half of the inclined plane structure may be formed in radially inner race structures <NUM>a and <NUM>b. In the shown embodiment, radially inner race structures <NUM>a and <NUM>b are operatively coupled to race load ramp inner parts, <NUM>a and <NUM>b respectively, of a race load ramp. In this embodiment a ball ramp is shown, but other torque sensitive inclined plane structures are also contemplated. The ball ramp of the present embodiment includes race load ramp inner parts <NUM>a and <NUM>b, race load ramp outer parts <NUM>a and <NUM>b, and an intermediate spherical structure <NUM>a and <NUM>b such as a ball, oblate or roller pin. In other embodiments, the inner half of the inclined plane structure may be formed in radially inner race structures <NUM>a and <NUM>b, and not be a separate structure. The radially inner race structures <NUM>a and <NUM>b may be operatively coupled to shaft <NUM> via splines <NUM> in the current embodiment. However, additional coupling mechanisms are contemplated as disclosed above. Additionally, in the present embodiment, radially inner race structures <NUM>a and <NUM>b are operatively coupled to shaft <NUM> via intermediate race load ramp inner parts <NUM>a and <NUM>b respectively. Race load ramp inner parts <NUM>a and <NUM>b are in turn operatively coupled to shaft <NUM> via a spline or other coupling mechanism. The radially inner race structures <NUM>a and <NUM>b may be operatively coupled to shaft <NUM> via splines <NUM> in the current embodiment with different intermediate structures or no intermediate structures.

The spherical structure of inclined planes <NUM>a and <NUM>b are also operatively coupled to race load ramp inner parts <NUM>a and <NUM>b and race load ramp outer parts <NUM>a and <NUM>b to establish symmetrical urging of radially inner race structures <NUM>a and <NUM>b inward during changes in torque. Similarly, inclined planes <NUM>a and <NUM>b may relax inward urging of radially inner race structure <NUM>a and <NUM>b during a reverse in torque. An example of an inclined plane structure may include a ball ramp splined to shaft <NUM> and operatively coupled to radially inner race structures <NUM>a and 23b via race load ramp inner parts <NUM>a and <NUM>b. Spring <NUM> also establishes an inwardly urging preload force on radially inner race structures <NUM>a and <NUM>b to counter adjustments in transmission ratios at the outer race <NUM>. This preload force of spring <NUM> may be sufficient to cause clamping for radially inner races <NUM>a and <NUM>b in the present embodiment for compensation during shifting of the CVT. Additionally, spring <NUM> may function as a torsion damping mechanism to reduce backlash during torque transitions such as torque reversal in the CVT system. Spring <NUM> may apply a priming torque as described further above. It is understood that radially inner race structures <NUM>a and <NUM>b and race load ramp inner parts <NUM>a and 62b may instead be a single radially inner race structure or may be multiple components coupled between shaft <NUM> and the rolling contact surfaces with spherical planetary members <NUM>. Upon a torque transition, the clamping of the torque sensitive inclined plane mechanism adjusts. For example, in a torque reversal, the torque sensitive inclined plane mechanism is symmetrical and reverses to an opposite side of the ball ramp, roller ramp, etc. Application of a torsion damping mechanism (not shown in <FIG>) reduces backlash from such a torque transition with application of a priming torque to the system.

In an embodiment of <FIG>, race load ramp inner parts <NUM>a and <NUM>b have extension surfaces <NUM>a and <NUM>b respectively extending from respective facing surfaces between each race load ramp <NUM>a and <NUM>b. Similarly, extension surfaces <NUM>a and <NUM>b may extend from the radially inner race structures <NUM>a and <NUM>b in other embodiments; for example, where the race load ramp inner part and radially inner race structure are a single piece structure. In an embodiment, the extension surface <NUM>b fits into extension surface <NUM>a. The reverse relationship is contemplated in other embodiments as well as various combinations of geometrical shapes designed to fit together. Radially inner race structures <NUM>a and <NUM>b and/or race load ramp inner parts <NUM>a and <NUM>b remain axially movable with respect to one another. However, radially inner race structures <NUM>a and <NUM>b remain axially aligned. Moreover, extension surfaces <NUM>a and <NUM>b may be polygonal or have a spline feature to cause radially inner race structures <NUM>a and <NUM>b to be rotationally constrained to one another.

The radially inner race structures <NUM>a and <NUM>b are rotationally constrained with respect to one another and are under urging of a ball ramp, springs or other mechanisms. With this or similar embodiments, a spherical planetary member <NUM> cannot advance into the radially inner race structures <NUM>a and <NUM>b more on either side during a transmission ratio shift involving narrowing the orbit or radius of rotation of the spherical planetary member. This may occur with imperfect clamping by the radially inner race structures <NUM>a and <NUM>b in compensating on movement of spherical planetary member <NUM>. The race load ramp inner parts <NUM>a and <NUM>b and radially inner race structures <NUM>a and <NUM>b are approximately locked in timing and rotation such that one cannot advance on an inclined plane structure such as a ball ramp or helical interengagement differently from the other. This also has an effect of reducing or eliminating float of the spherical planetary member <NUM> due to any float of the hydraulically actuated radially outer race structures <NUM>a and <NUM>b. Control of float may also be controlled by control of hydraulic displacement to either or both sides of outer race <NUM>. However, rotationally constrained radially inner race structures <NUM>a and <NUM>b in addition to an inclined plane coupling of a ball ramp or other structure may also reduce or eliminate float of the inner race <NUM>, outer race <NUM> and spherical planetary members <NUM>. Reducing float may avoid potential damage to follower <NUM> or radial plates <NUM>a or <NUM>b due to axial misalignment.

In another embodiment discussed above but not shown, the race load ramp inner parts <NUM>a and <NUM>b are coupled to shaft <NUM> via a helical interengagement in the form of a screw threaded engagement. Torque on shaft <NUM> may cause urging of radially inner race structures <NUM>a and <NUM>b inwardly if screw threads are opposite for each of race load ramp inner parts <NUM>a and <NUM>b. Which direction of torque in shaft <NUM> urges the radially inner race structures <NUM>a and <NUM>b inwardly depends on the arrangement of the helical threading. The reverse torque direction will relax the helical interengagement and permit the radially inner race structures to separate. Either direction of torque on shaft <NUM> is contemplated to urge the radially inner race structures inward in such embodiments.

<FIG> show additional detail of race load ramp inner parts <NUM>a and <NUM>b as disclosed in one embodiment of <FIG>. <FIG> depicts a partial cross sectioned view of an inner race <NUM> according to an embodiment of the present invention. Radially inner race structure <NUM>a is coupled to race load ramp inner part <NUM>a in this embodiment. For simplicity, radially inner race structure <NUM>b is not shown coupled to race load ramp inner part <NUM>b. Each race load ramp inner part <NUM>a and <NUM>b is part of a ball ramp, such as that including spherical structures <NUM>a and <NUM>b respectively. Race load ramp inner part <NUM>a has an extension surface <NUM>a that fits correspondingly into a cavity formed by extension surface <NUM>b of race load ramp inner part <NUM>b. Extension surfaces <NUM>a and <NUM>b extend from surfaces facing one another between race load ramp inner parts <NUM>a and <NUM>b during operation. Extension surfaces <NUM>a and <NUM>b still allow race load ramp inner parts <NUM>a and <NUM>b to move axially in alignment. Any combination of extension surfaces or edges of surfaces <NUM>a and <NUM>b in geometries that fit together is contemplated.

<FIG> depicts an angle view of race load ramp inner part 62a according to one embodiment. As can be seen from <FIG>, extension surface <NUM>a is such that a polygonal cavity is established inside an edge of extension surface <NUM>a. <FIG> depicts an angle view of race load ramp inner part 62b according to one embodiment. As can be seen from <FIG>, extension surface <NUM>b is a polygonal extension surface that fits correspondingly into polygonal cavity of extension surface <NUM>a. In other embodiments, extension surfaces extension surfaces <NUM>a and <NUM>b may be of other shapes so as to fit correspondingly and maintain rotational symmetry between race load ramp inner parts <NUM>a and <NUM>b and, thus, radially inner race structures such as those described in embodiments above. Similarly, other embodiments may use a spline, dowel pegs, or other structures to rotationally constrain race load ramp inner parts <NUM>a and <NUM>b while allowing axial movement as is understood. As explained in other embodiments, similar structure to rotationally constrain may be designed into radially inner race structures <NUM>a and <NUM>b directly, or additional intermediate structures may be used to rotationally constrain radially inner race structures <NUM>a and <NUM>b with respect to one another.

<FIG> shows a continuously variable transmission (CVT) in another embodiment of the present invention. In the example embodiment, the CVT is a variable radius epicyclical transmission device. In this embodiment the same reference numerals are used to identify the same or similar components as in other embodiments.

In the example embodiment of <FIG>, the CVT shown depicts a housing <NUM> within which is mounted a sun shaft <NUM> bearing rolling element bearings <NUM>, <NUM>. Planet carrier <NUM> carries three planet follower members <NUM>. The planet follower members <NUM> are rotatably borne on the planet carrier <NUM> by planet follower shafts <NUM>. Any number of planet follower members <NUM> are contemplated and may depend on the number of spherical planetary members <NUM>. The spherical planetary members <NUM> are substantially spherical as described above with respect to <FIG>. Spherical planetary members are captive between radially inner races <NUM> and the radially outer races <NUM>, with planet follower members <NUM> circumferentially intercalated between adjacent pairs of spherical planetary members <NUM> for transmitting drive to or from the said spherical planetary members <NUM>. In an embodiment, planet follower members <NUM> are carried on planet carrier <NUM> by planet follower shafts <NUM> which transmit drive to or from spherical planetary members <NUM> in operation of the CVT device.

The planet carrier <NUM> effectively includes a radial plate together with shouldering studs forming the planet follower shafts <NUM>. In the present embodiment, outer race structures <NUM>a and <NUM>b are rotationally constrained to housing <NUM> causing housing <NUM> to rotate as an output. It is understood that the input and output relationship described above may also be reversed in other embodiments.

Sun shaft <NUM> may carry a radially inner race <NUM> comprising a sun member further comprising two structures <NUM>a, <NUM>b which are engaged to the shaft <NUM>. Radially inner race <NUM> may be coupled to the input shaft via a coupling comprising a spline or other coupling including a helical interengagement in the form of a screw threaded engagement (not shown). In one embodiment, radially inner race structures <NUM>a and <NUM>b are coupled to shaft <NUM> via a spline. Radially inner race structures <NUM>a and <NUM>b are axially movable along the axis of rotation of the sun shaft <NUM>. Inward axial movement may be urged by a mechanical, electromechanical, or hydraulic mechanism as described in embodiments below.

The radially inner race structures <NUM>a, 23b are coupled to hydraulic cavity structures <NUM>a and <NUM>b via hydraulic cavity <NUM>. Hydraulic cavity structures, such as inner race hydraulic cavity housings <NUM>a and <NUM>b serve as a side of hydraulic cavity <NUM> and are coupled to sun shaft <NUM>. As shown in one example embodiment, inner race hydraulic cavity housing <NUM>b is coupled to sun shaft <NUM> via a threaded screw coupling which holds inner race hydraulic cavity housing <NUM>a in place relative to a stop limit structure coupled to shaft <NUM>. As before, shaft <NUM> may serve as an input or output shaft depending on configuration.

Hydraulic cavity <NUM> may act as an axial adjustment mechanism for radially inner race structures <NUM>a and <NUM>b via hydraulic displacement. Sealing mechanisms <NUM> such as an o-ring or fluid bearing seal form a hydraulic seal for cavity <NUM> between inner race hydraulic cavity housings <NUM>a, <NUM>b and radially inner race structures <NUM>a, <NUM>b. Other axial adjustment mechanisms are also contemplated in different embodiments including a mechanical system such as a lever or arm, screw mechanism, and electromechanical mechanism or other mechanism to axially adjust the distance between radially inner race structures <NUM>a, <NUM>b. In other embodiments, hydraulic cavity <NUM> may be formed between radially inner race structures <NUM>a, <NUM>b and an inner race hydraulic cavity housing not coupled to an input or an output shaft (not shown). In one such embodiment therefore, the inner race assembly may be rotatable with respect to an input or output shaft, including radially inner race structures <NUM>a, <NUM>b. In yet other embodiments, the hydraulic cavity <NUM> may be formed between radially inner race structures <NUM>a, <NUM>b and extensions of housing <NUM>. In such an embodiment, the radially inner race structure <NUM>a, <NUM>b may be rotatable relative to housing <NUM> of the CVT which itself may be fixed or rotatable.

Spherical planetary members <NUM> are engaged between the radially inner race <NUM> and a radially outer race <NUM> also comprising two axially separated annular race structures <NUM>a, <NUM>b. Rolling contact surfaces of the race structures <NUM>a, <NUM>b and <NUM>a, 26b, respectively identified as <NUM>a, <NUM>b and <NUM>a, <NUM>b, each comprise an arcuate surface in cross-section the radius of which is slightly greater than the radius of the spherical planetary members <NUM>.

In the presently shown embodiment, preload springs <NUM> are used to apply a preload force to urge axial movement of radially outer race structures <NUM>a and <NUM>b. These preload springs may serve a dual purpose as described in embodiments above. Preload springs <NUM> may be heavy enough to serve as torsion damping mechanisms. Torsion damping mechanisms <NUM> apply torque sufficient to reduce backlash during torsional transition of the CVT of the present invention. Radially outer race structures <NUM>a and <NUM>b may be coupled to housing <NUM> via a torque sensitive inclined plane structure, such as ball ramp <NUM>a and <NUM>b. In the present embodiment, torsion damping mechanism (and preload spring) <NUM> is operatively coupled to the torque sensitive inclined plane structure <NUM>a and <NUM>b. In an embodiment, the torsion damping mechanism (and preload spring) <NUM> is operatively coupled to housing <NUM> which may be rotating. In other embodiments, not shown, torsion damping mechanism (and preload spring) <NUM> may operatively coupled to an annular shaft that may serve as either an input or output shaft.

In yet another embodiment, a separate torsion damping mechanism may be used (not shown). Such a separate torsion damping mechanism may be operatively coupled to the torque sensitive inclined plane mechanism of an outer race similar to the presently described embodiment. The separate torsion damping mechanism may be operatively coupled to housing <NUM> or an annular shaft in various embodiments.

Torsional drive and torsional transitions may be received into the CVT system via the sun shaft, housing, or an annular shaft depending upon the embodiment. As described herein, any of a sun shaft <NUM>, housing <NUM>, annular shaft (not shown) or carrier shaft may serve as input or output depending upon the coupling of the CVT systems described in embodiments herein.

Other couplings to the housing <NUM> are also contemplated including helical interengagement by one or both radially outer race structures <NUM>a and <NUM>b. Thread direction may be used to cause axial movement of one or both structures depending on rotation applied to radially outer race structures <NUM>a and <NUM>b. Radially outer race structures <NUM>a and <NUM>b may be non-rotatable in that only some rotation may occur via the helical interengagement or an inclined plane as described. In some embodiments, the two radially outer race structures <NUM>a and <NUM>b may be coupled via oppositely handed threads so that, for reasons which are described in more detail in above and in <CIT>, a relative rotation of the radially outer race structures <NUM>a and <NUM>b relative to housing <NUM> in one directional sense will cause the two race structures to be displaced towards one another to clamp radially outer race structures <NUM>a and <NUM>b to spherical planetary member <NUM>. Similarly, axial separation of the two radially outer race structures <NUM>a and <NUM>b occurs where there is relative rotation in the opposite directional sense. In other embodiments, radially outer race structures <NUM>a and 26b may be rotatable relative to housing <NUM> as well as inner race <NUM>, and follower members <NUM>.

In operation, sun shaft <NUM>, as an input shaft in one embodiment, transmits rotation of the shaft <NUM> to the inner race <NUM>, the rotation of which causes rotation of the spherical planetary members <NUM> by rolling contact. The spherical planetary members <NUM> are in rolling contact with outer race <NUM>. In one embodiment, outer race <NUM> may be non-rotating relative to rotation of the CVT housing <NUM>. In the shown embodiment, housing <NUM> rotates as an output. In other embodiments, outer race <NUM> may rotate and connect to an output shaft. Rotation of the spherical planetary members <NUM> is transmitted via the planet followers <NUM> to the planet carrier <NUM> and thus to an output shaft <NUM> in one embodiment. In other embodiments, the planet carrier <NUM> is held at zero rotation and the rotation is transmitted to outer race <NUM>. Spherical planetary members <NUM> are also in rolling contact with outer race <NUM>. By hydraulic displacement in hydraulic chamber <NUM> via either increased or decreased hydraulic fluid, the two radially inner race structures <NUM>a, <NUM>b of the inner race can be urged towards one another or allowed to move axially away from one another respectively.

Axial approach of the two radially inner race structures <NUM>a, 23b applies pressure to the spherical planetary members <NUM> causing the spherical planetary members <NUM> to move radially outwardly and urge the two radially outer race structures <NUM>a, <NUM>b apart to increase transmission ratio. In an embodiment, a ball ramp <NUM>a and 64b between the radially outer race structures <NUM>a, <NUM>b and the spring <NUM> and housing <NUM> act in effect as a torque-sensitive mechanism in that the ball ramp limits rotation of the two radially outer race structures <NUM>a, <NUM>b in either direction relative to the housing <NUM> in the current embodiment. Rotation of the outer race <NUM> in either direction causes the race structures <NUM>a, <NUM>b to approach one another axially when resisted by drag so that any play in the rolling contact between the races and the spherical planetary members <NUM> is taken up and compensated by the tendency of the race structures <NUM>a, <NUM>b to approach one another until the forces exerted on the ball ramps <NUM>a, <NUM>b between the race structures <NUM>a, <NUM>b and the housing <NUM> matches the reaction forces between the race structures <NUM>a, <NUM>b and the spherical planetary members <NUM>. At this point no further relative axial displacement of the race structures <NUM>a, <NUM>b takes place and drive transmission takes place at a transmission ratio determined by the radial position of the spherical planetary members <NUM> relative to shaft <NUM>. Alternatively or in addition, the radially outer race structures may utilize a torque-sensitive coupling in the form of a helical interengagement such as that described in embodiments above. Other torque-sensitive mechanism arrangements are also contemplated using a variety of inclined plane structures which may or may not include rotating or ball structures to reduce friction.

As can be seen in <FIG>, radially inner race structures <NUM>a and <NUM>b form inner race <NUM> which may be in rolling contact with spherical planetary member <NUM>. Hydraulic cavity <NUM> is formed between radially inner race structures <NUM>a and <NUM>b and inner race hydraulic cavity housings <NUM>a and <NUM>b. It is understood that a hydraulic cavity <NUM> need only be formed on one side of race <NUM> to function as an axial displacement control mechanism for race <NUM>. In other embodiments, CVT housing <NUM> may serve as inner race hydraulic cavity housings <NUM>a and <NUM>b as described above. In yet other embodiments, hydraulic cavity <NUM> may be formed between radially inner race structures <NUM>a and <NUM>b and an inner race hydraulic cavity housing, which may include an outer race hydraulic cavity housing (not shown), separate from the CVT housing <NUM>. Hydraulic port <NUM> permits adjustment to hydraulic pressure and fluid levels in the hydraulic cavity <NUM>. Input or removal of hydraulic fluid may be made via connector port <NUM>. Hydraulic port <NUM> is linked to connector port <NUM> via a hydraulic line <NUM> and in shaft <NUM>. Since shaft <NUM> may be rotating, hydraulic line <NUM> may link to connector port <NUM> via a rotating hydraulic connection <NUM>. In the embodiment of <FIG>, hydraulic port <NUM> provides uniform application of hydraulic pressure in a common hydraulic cavity <NUM> associated with radially inner race structures <NUM>a and <NUM>b. Hydraulic displacement with increase of hydraulic fluid will axially urge radially inner race structures <NUM>a and <NUM>b together while reduction of hydraulic fluid will cause negative displacement and allow radially inner race structures <NUM>a and <NUM>b to separate axially. Thus, some uniformity and symmetry may be maintained between radially inner race structures <NUM>a and <NUM>b, especially when positive hydraulic pressure is applied.

Nonetheless, it is possible for radially inner race structures <NUM>a and <NUM>b to float or slide to one or the other side causing spherical planetary members <NUM> and outer race <NUM> to also potentially slide in some embodiments. This is addressed more fully similar to the embodiments described above for <FIG>. Input port <NUM> allows for hydraulic fluid connection to the CVT to allow control over hydraulic displacement for radially inner race structures <NUM>a and <NUM>b via one or more hydraulic cavities <NUM>. Sealing mechanisms <NUM> are used to establish a hydraulic cavity between radially inner race structures <NUM>a and <NUM>b and inner race hydraulic cavity housing <NUM> in the current embodiment. An inner race hydraulic cavity housing or other hydraulic cavity structure may also be fitted with radially inner race structures <NUM>a and <NUM>b of varied shapes (not shown) to accommodate a hydraulic cavity in other embodiments. The sealing mechanisms <NUM> may be an o-ring, a sealing layer, or a fluid bearing formed of hydraulic fluid at a junction point or points that are in close proximity between radially inner race structures <NUM>a and <NUM>b and hydraulic structures <NUM>a, <NUM>b. In the present embodiment, only three sealing mechanisms <NUM> are shown, two between the hydraulic structures <NUM>a, 20b and radially inner race structures <NUM>a and <NUM>b and one between radially inner race structures <NUM>a and <NUM>b. Such junction points may be, for example, edges or shoulders of radially inner race structures <NUM>a and <NUM>b and corresponding edges or shoulders of inner race hydraulic cavity housing <NUM>a, <NUM>b or the other radially inner race structure designed to fit together in close proximity. The sealing mechanisms <NUM> may permit radially inner race structures <NUM>a and <NUM>b to still move axially. In some embodiments, sealing mechanisms <NUM> may permit radially inner race structures <NUM>a and <NUM>b to rotate about the axis shaft <NUM>.

Similar to that described above, it may be seen that when the radius of rolling contact between the spherical planetary members <NUM> and the inner race <NUM> is relatively small and the radius of contact between the spherical planetary members <NUM> and the outer race <NUM> is also relatively small, the transmission ratio between the shaft <NUM> and rotating housing <NUM> or an output shaft (not shown) is at a low level. By actuating hydraulic displacement in hydraulic cavity <NUM>, radially inner race structures <NUM>a and <NUM>b are urged to move together so that the spherical planetary members <NUM> can move radially outwardly compensated by axial approach of the radially outer race structures <NUM>a, <NUM>b having arcuate rolling contact surfaces <NUM>a, <NUM>b. This increases the transmission ratio between the shaft <NUM> and output drive source such as rotating housing <NUM> or an output shaft. It is appreciated that a reverse ratio relationship may be established by reversing an output drive source and an input drive source.

By relaxing hydraulic displacement in hydraulic cavity <NUM> via negative displacement, radially inner race structures <NUM>a and <NUM>b are allowed to move apart so that the spherical planetary members <NUM> can move radially outwardly again compensated by axial approach of the radially outer race structures <NUM>a, <NUM>b. This again reduces the transmission ratio.

In the CVT embodiments described herein, arrangement of input and output is not limited to as described above in <FIG>. It is understood that one or more input shafts may be linked to any one or more of the inner race <NUM>, planet carrier <NUM>, or outer race <NUM>. Likewise, it is contemplated that one or more output shafts or other structures may be linked to any one or more of the inner race <NUM>, planet carrier <NUM>, or outer race <NUM> in various embodiments. Further, housing <NUM> may serve as an input or output of drive rotation and be coupled non-rotatably to any one or more of the inner race <NUM>, planet carrier <NUM>, or outer race <NUM>. Any combination of input drive rotation via shaft, gear connection/hub, rotational housing, belt drive, or other is contemplated.

<FIG> shows an axial cross-section view of an inner race assembly <NUM> of a continuously variable transmission (CVT) according to an embodiment of the present invention. Inner race assembly <NUM> includes shaft <NUM>, radially inner race structures <NUM>a and <NUM>b, inner race hydraulic cavity housings <NUM>a and <NUM>b, and a plurality of sealing mechanisms <NUM>. Hydraulic port <NUM> is connected to hydraulic line <NUM> within shaft <NUM>. Since <FIG> is also an exploded view for ease of viewing, hydraulic cavities are not shown intact but would be formed between radially inner race structures <NUM>a and <NUM>b and inner race hydraulic cavity housings <NUM>a and 20b which slide inwardly on shaft <NUM> and fit correspondingly into radially inner race structures <NUM>a and <NUM>b. Inner race hydraulic cavity housing 20b is shown with helical threads <NUM> for attachment on corresponding threads <NUM> on shaft <NUM>.

Radially inner race structures <NUM>a and <NUM>b are shown and include arcuate rolling contact surfaces <NUM>a and <NUM>b. Sealing mechanisms <NUM> are shown in the present embodiment mounted on an edge <NUM>a and <NUM>b of a disc-like extension of inner race hydraulic cavity housings <NUM>a and 20b that correspond to a shoulder or edge <NUM>a and <NUM>b of a surface opposite to arcuate rolling contact surfaces <NUM>a and <NUM>b of radially inner race structures <NUM>a and <NUM>b. Corresponding edges or shoulders of radially inner race structures <NUM>a and <NUM>b and inner race hydraulic cavity housings <NUM>a and <NUM>b may be of any geometry to establish surfaces in close proximity to form a seal with a sealing mechanism. Edge <NUM>a and <NUM>b is designed to nest into a corresponding edge or shoulder surface <NUM>a and <NUM>b of radially inner race structures <NUM>a and <NUM>b to establish a hydraulic seal on one side of a hydraulic cavity In other embodiments, sealing mechanisms <NUM> could also be mounted on the shoulder or edge <NUM>a or <NUM>b of radially inner race structures <NUM>a and <NUM>b in close proximity to inner race hydraulic cavity housings <NUM>a and <NUM>b. In yet other embodiments, such as with a fluid bearing, sealing mechanisms may not be mounted on either edge or surface, but form a seal by virtue of the proximity of the surfaces and presence of hydraulic fluid. In this example, embodiment o-ring sealing mechanisms are shown, but several alternate sealing mechanisms are contemplated including example embodiments discussed further above.

An additional sealing mechanism <NUM> may be mounted on an extension surface <NUM>b of radially inner race structure <NUM>b that fits correspondingly into a cavity formed by extension surface <NUM>a of radially inner race structure <NUM>a. Extension surfaces <NUM>a and <NUM>b extend from surfaces between radially inner race structures <NUM>a and <NUM>b. Extension surfaces <NUM>a and <NUM>b still allow radially inner race structures <NUM>a and <NUM>b to move axially in alignment. Extension surfaces <NUM>a and <NUM>b need not rotatably limit radially inner race structures <NUM>a and <NUM>b with respect to one another in one embodiment. In other words, the extension surfaces <NUM>a and <NUM>b may be circular to allow rotation of radially inner race structures <NUM>a and <NUM>b. In other embodiments, extension surfaces <NUM>a and <NUM>b may rotatably limit radially inner race structures <NUM>a and <NUM>b with respect to one another similar to that described with reference to FIGs. Extension surface <NUM>b may be such that a polygonal cavity is established inside an edge of extension surface <NUM>b. Extension surface <NUM>a may be a polygonal extension surface that fits correspondingly into polygonal cavity of extension surface <NUM>b. In other embodiments, extension surfaces <NUM>a and <NUM>b may be of other shapes so as to fit correspondingly and maintain rotational symmetry between radially inner race structures <NUM>a and <NUM>b or race load ramp inner parts as described above. For example, other embodiments may use a spline, dowel pegs, or other structures to rotationally constrain radially inner race structures <NUM>a and <NUM>b while allowing axial movement as is understood. In the current embodiment, extension surfaces <NUM>a and <NUM>b establish surfaces in close proximity and a sealing mechanism may be mounted or formed between them to form a second hydraulic seal on another side of the hydraulic cavity. Hydraulic seam mechanisms similar to the sealing mechanisms described above may be used. As shown in <FIG>, for example, a sealing mechanism <NUM> that may be an o-ring is mounted to extension surface <NUM>b of radially inner race structure <NUM>b. In other embodiments, sealing mechanism <NUM> may be mounted to extension surface <NUM>a. In yet another embodiment, one or more additional edges or shoulders may be formed elsewhere on radially inner race structures <NUM>a and <NUM>b with a corresponding edge or shoulder structure on inner race hydraulic cavity housings <NUM>a and <NUM>b to form a second hydraulic seal by virtue of surfaces of radially inner race structures <NUM>a and <NUM>b and inner race hydraulic cavity housings <NUM>a and <NUM>b being in close proximity and having a sealing mechanism. The one or more additional hydraulic sealing mechanisms of these embodiments establish another side of the hydraulic cavity.

The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, components, and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.

When an element is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. As used herein, the term "or" includes any and all combinations of one or more of the associated listed items. For example, a list of items A or B is satisfied by any one of the following: just A is present or occurs, just B is present or occurs, and both A and B are present or occur. Similarly, in descriptions of embodiments in the specification the term "and" is similarly broad and the various embodiments contemplated may include any and all combinations of one or more of the associated listed items.

Claim 1:
A radially inner race and a radially outer race for a continuously variable transmission comprising:
the radially inner race (<NUM>), having a first inner race structure (23a) and a second inner race structure (23b) spaced along an axis wherein at least one of the first inner race structure (23a) or the second inner race structure (23b) is axially movable;
the radially outer race (<NUM>), having a first outer race structure (26a) and a second outer race structure (26b) spaced along an axis wherein at least one of the first outer race structure (26a) or the second outer race structure (26b) is axially movable;
planetary members (<NUM>) in rolling contact with the radially outer race (<NUM>);
at least one of the first and second outer race structures (26a, 26b) operatively coupled to a torque sensitive inclined plane structure (64a, 64b), where the torque sensitive inclined plane structure is a ramp, a ball ramp, or a roller ramp; characterized in that the first inner race structure and the second inner race structure are rotationally constrained with respect to each other; and
a torsion damping mechanism (<NUM>) operatively coupled to the first outer race structure (26a) to apply torque to the first outer race structure to reduce a transition amplitude during a torque impulse.