Cam mechanism, power transmission path switching device, and two-speed transmission

Abstract

The present invention provides a cam mechanism structure that can prevent the generation of unpleasant noises and vibrations at the spline engagement portion between the support member and the driven cam when the rotational phase of the driven cam changes. [Solution] The drive cam 41 has a rotational phase in which the direction of the circumferential component of the force acting from the drive cam 41 to the driven cam 42 is in a predetermined direction, and a second phase in which the direction of the circumferential component of the force acting from the drive cam 41 to the driven cam 42 is in the opposite direction to the predetermined direction. The side member 44 applies a rotational restricting force to the driven cam 42 having a circumferential component in the predetermined direction, based on the biasing force of the biasing member 45. The magnitude of the torque based on the circumferential component of the rotational restricting force is greater than the magnitude of the torque based on the circumferential component of the force acting from the drive cam 41 to the driven cam 42 in the second phase.

Description

Technical Field

[0001] The present disclosure relates to a cam device, a power transmission path switching device, and a two-speed transmission.

Background Art

[0002] In recent years, in response to the trend of reducing fossil fuel consumption, research on electric vehicles and hybrid vehicles has progressed and has been implemented in some fields. Different from an internal combustion engine (engine) that operates by directly burning fossil fuel, an electric motor that serves as a power source for electric vehicles and hybrid vehicles generally generates maximum torque at startup, and its characteristics of output shaft torque and rotation speed are favorable for automotive applications. Therefore, it is not necessary to provide a transmission like that in a conventional automobile using an internal combustion engine as a driving source. However, even when an electric motor is used as a driving source, acceleration performance and high-speed performance can be improved by providing a transmission. Specifically, by providing a transmission, the relationship between the traveling speed and acceleration of the vehicle can be made smooth, similar to that of an automobile equipped with an engine and a transmission in the power transmission system. This point will be described with reference to FIG. 21.

[0003] For example, if a power transmission with a large reduction ratio is placed between the motor output shaft of an electric motor and the differential input element of a differential gear connected to the drive wheels, the relationship between the acceleration (G) and driving speed (km / h) of the electric vehicle will conceptually be as shown by solid line a in Figure 21. In other words, acceleration performance at low speeds will be excellent, but high-speed driving will be impossible. Conversely, if a power transmission with a small reduction ratio is placed between the motor output shaft and the differential input element, the above relationship will be as shown by dashed line b in Figure 21. In other words, high-speed driving will be possible, but acceleration performance at low speeds will be impaired. Conversely, if a transmission is provided between the motor output shaft and the differential input element, and the reduction ratio of this transmission is changed according to the vehicle speed, characteristics can be obtained that are a continuation of the portion to the left of point P in solid line a and the portion to the right of point P in dashed line b. These characteristics are almost equivalent to those of an engine-powered vehicle with similar output, as shown by the dashed line c in Figure 21, indicating that it can achieve performance equivalent to an engine-powered vehicle equipped with a transmission in its power transmission system in terms of acceleration and high-speed performance.

[0004] International Publication No. 2023 / 248571 discloses the structure of a drive system for an electric vehicle in which the output torque of an electric motor, which is the drive source, is increased by a two-speed transmission equipped with an electric friction clutch device that can switch between connected mode and disconnected mode, and a rotational transmission state switching device that can switch between locked mode, free mode and one-way clutch mode, and transmitted to a differential gear. In this drive system for an electric vehicle, by switching the mode of the electric friction clutch device and the mode of the rotational transmission state switching device, the two-speed transmission can be switched between a reduced speed ratio mode in which the reduction ratio between the input member and the output member is small, and a high reduction ratio mode in which the reduction ratio is larger than that of the reduced speed ratio mode.

[0005] Specifically, by switching the electric friction clutch device to the disconnection mode and the rotation transmission state switching device to the lock mode, the two-speed transmission can be switched to the high reduction ratio mode. By switching the electric friction clutch device to the connection mode and the rotation transmission state switching device to the free mode, the two-speed transmission can be switched to the low reduction ratio mode.

[0006] More specifically, the mode of the electric friction clutch device and the mode of the rotational transmission state switching device are switched by driving a cam mechanism provided in the electric friction clutch device.

[0007] The cam mechanism comprises a support member (cylindrical member), a drive cam, a driven cam, and a biasing member.

[0008] The support member has a male spline section and is supported and fixed to a fixed part, such as a housing, that does not rotate or displace during use.

[0009] The drive cam is supported by a support member in a way that prevents axial displacement but allows rotation. The drive cam has a drive cam surface on one axial side, which is a surface with irregularities in the circumferential direction.

[0010] The driven cam has a female spline portion, which is spline-engaged with the male spline portion of the support member, and is positioned on one axial side of the driven cam. That is, the driven cam is supported by the support member based on this spline engagement, preventing rotation but allowing axial displacement. In other words, the driven cam and the driven cam are supported in a way that allows relative rotation and relative axial displacement. The driven cam supports a plurality of rolling elements that roll in contact with the surface of the driven cam.

[0011] The biasing member elastically biases the driven cam toward the other axial direction. That is, the biasing member applies an elastic force that presses the multiple rolling elements supported by the driven cam toward the drive cam surface in the axial direction.

[0012] In such a cam mechanism, when the drive cam is rotationally driven, multiple rolling elements supported by the driven cam move circumferentially along the surface of the drive cam. As a result, the driven cam moves axially relative to the drive cam, causing the axial distance between the drive cam and the driven cam to expand or contract.

[0013] The electric friction clutch device has a friction engagement portion having at least one first friction plate and at least one second friction plate, which are supported to allow relative axial displacement, and is configured to be switchable between a connection mode in which the first friction plate and the second friction plate are pressed against each other, and a disconnection mode in which the force pressing the first friction plate and the second friction plate against each other is released, based on expanding or contracting the axial distance between the drive cam and the driven cam.

[0014] The rotational transmission state switching device has a mode select member that rotates in conjunction with the rotation of the drive cam, and is configured to switch between a locked mode, a free mode, and a one-way clutch mode based on the rotation of the mode select member. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] International Publication No. 2023 / 248571 [Overview of the project] [Problems that the invention aims to solve]

[0016] In the cam apparatus described in International Publication No. 2023 / 248571, the drive cam has, as rotational phases, a first phase in which the direction of the circumferential component of the force acting from the drive cam to the driven cam is in a predetermined direction, and a second phase in which the direction of the circumferential component of the force acting from the drive cam to the driven cam is in the opposite direction to the predetermined direction.

[0017] In other words, the drive cam surface provided on the drive cam includes a first inclined surface portion that is inclined in a direction toward one axial side as it moves toward one side in the circumferential direction, and a second inclined surface portion that is inclined in a direction toward one axial side as it moves toward the other side in the circumferential direction.

[0018] As the drive cam rotates, the multiple rolling elements supported by the driven cam move circumferentially along the first inclined surface. In the phase of the drive cam, the force F1 acting on the multiple rolling elements from the first inclined surface can be decomposed into an axial component fa1 directed in one axial direction and a circumferential component fc1 directed in the other circumferential direction (a predetermined direction). In other words, as the drive cam rotates, the rotational phase of the drive cam as the multiple rolling elements supported by the driven cam move circumferentially along the first inclined surface becomes the first phase in which the direction of the circumferential component of the force acting from the drive cam to the driven cam becomes the predetermined direction.

[0019] In contrast, as the drive cam rotates, the rotational phase of the drive cam, when multiple rolling elements supported by the driven cam move circumferentially along the second inclined surface, can be decomposed into an axial component fa2 that is directed in one axial direction and a circumferential component fc2 that is directed in one circumferential direction (opposite to the predetermined direction). In other words, as the drive cam rotates, the rotational phase of the drive cam, when multiple rolling elements supported by the driven cam move circumferentially along the second inclined surface, is a second phase in which the direction of the circumferential component of the force acting from the drive cam to the driven cam is opposite to the predetermined direction.

[0020] On the other hand, a small circumferential gap is provided at the spline engagement portion between the male spline portion of the support member and the female spline portion of the driven cam in order to allow smooth axial sliding of the female spline portion relative to the male spline portion.

[0021] Therefore, in a first phase in which a force in the predetermined direction (the other circumferential side of the drive cam surface) acts from the drive cam to the driven cam, the side surface on the other circumferential side of the teeth of the female spline portion of the driven cam abuts against the side surface on one circumferential side of the teeth of the male spline portion of the support member, and the side surface on one circumferential side of the teeth of the female spline portion and the side surface on the other circumferential side of the teeth of the male spline portion face each other with a minute gap therebetween. In contrast, in a second phase in which a force in a direction opposite to the predetermined direction (one circumferential side of the drive cam surface) acts from the drive cam to the driven cam, the side surface on one circumferential side of the teeth of the female spline portion of the driven cam abuts against the side surface on the other circumferential side of the teeth of the male spline portion of the support member, and the side surface on the other circumferential side of the teeth of the female spline portion and the side surface on one circumferential side of the teeth of the male spline portion face each other with a minute gap therebetween.

[0022] Therefore, when the rotational phase of the drive cam is switched from the first phase to the second phase or from the second phase to the first phase, the driven cam rotates relative to the support member by an amount corresponding to the minute gap, and the side surfaces of the teeth of the female spline portion and the teeth of the male spline portion collide with each other, which may cause unpleasant abnormal noise and vibration called rattling noise.

[0023] An object of the present disclosure is to provide a structure of a cam device that can prevent unpleasant abnormal noise and vibration from being generated at the engagement portion between a support member and a driven cam when the rotational phase of a drive cam changes. [Means for Solving the Problem]

[0024] A cam device according to one aspect of the present disclosure includes: a support member having a support member-side engaging portion; a drive cam supported so as to be rotatable relative to the support member and incapable of axial displacement relative to the support member; A driven cam having a driven cam side engaging portion, which is disposed on one axial side of the driving cam in a state where the driven cam side engaging portion is engaged with the support member side engaging portion so as to allow axial displacement and restrict rotation, and expands or contracts an axial distance between the driven cam and the driving cam by being displaced in the axial direction relative to the support member as the driving cam rotates; A side member having a side member side engaging portion, which is disposed on one axial side of the driven cam in a state where the side member side engaging portion is engaged with the support member side engaging portion so as to allow axial displacement and restrict rotation; A biasing member that elastically biases the side member toward the other axial side.

[0025] The driving cam has, as rotational phases, a first phase where a direction of a circumferential component of a force acting from the driving cam to the driven cam is a predetermined direction, and a second phase where the direction of the circumferential component of the force acting from the driving cam to the driven cam is opposite to the predetermined direction.

[0026] The side member applies a rotation restricting force having a circumferential component in the predetermined direction to the driven cam based on the biasing force of the biasing member.

[0027] A magnitude of torque based on the circumferential component of the rotation restricting force is larger than a magnitude of torque based on the circumferential component of the force acting from the driving cam to the driven cam in the second phase.

[0028] In the cam device according to one aspect of the present disclosure, the engaging portions between the support member side engaging portion and the driven cam side engaging portion, and between the support member side engaging portion and the side member side engaging portion, are formed by spline engaging portions.

[0029] A cam device according to one aspect of the present disclosure has one of the following configurations for expanding or contracting the axial distance between the drive cam and the driven cam in accordance with the rotation of the drive cam: a configuration in which the drive cam surface provided on the drive cam and the driven cam surface provided on the driven cam slide directly against each other; a configuration in which a plurality of rolling elements are sandwiched between the drive cam surface provided on the drive cam and the driven cam surface provided on the driven cam; or a configuration in which a plurality of rolling elements supported by one of the cams, the drive cam or the driven cam, are brought into rolling contact with the cam surface provided on the other of the cams, the drive cam or the driven cam.

[0030] A cam device according to one aspect of the present disclosure has one of the following configurations for the side member to apply the rotational restricting force to the driven cam based on the biasing force of the biasing member: a configuration in which a receiving preload cam surface provided on the driven cam and a pushing preload cam surface provided on the side member are in direct contact; a configuration in which an engaging element is sandwiched between the receiving preload cam surface provided on the driven cam and the pushing preload cam surface provided on the side member; and a configuration in which an engaging element supported on one of the driven cam and the side member is in contact with a preload cam surface provided on the other of the driven cam and the side member.

[0031] A power transmission path switching device according to one aspect of the present disclosure comprises an electric friction clutch device and a rotational transmission state switching device.

[0032] The aforementioned electric friction clutch device, First clutch member and A second clutch member is supported coaxially with the first clutch member and capable of relative rotation with respect to the first clutch member, A friction engagement portion is provided between the first clutch member and the second clutch member, having at least one first friction plate and at least one second friction plate, which are supported to allow relative axial displacement, A cam device comprising a drive cam and a driven cam supported to allow relative rotation and relative axial displacement with respect to the drive cam, wherein the axial distance between the drive cam and the driven cam expands and contracts as the drive cam rotates, The system includes an electric actuator that rotates the drive cam, and The device is configured to be switchable between a connection mode, in which torque is transmitted between the first clutch member and the second clutch member by pressing the at least one first friction plate and the at least one second friction plate against each other based on expanding or contracting the axial distance between the drive cam and the driven cam, and a disconnection mode, in which torque is not transmitted between the first clutch member and the second clutch member by releasing the force pressing the at least one first friction plate and the at least one second friction plate against each other.

[0033] The rotation transmission state switching device is A first member and a second member arranged coaxially with respect to each other, The system includes a mode select member that rotates or is displaced axially in conjunction with the rotation of the drive cam, Based on the rotation or axial displacement of the mode select member, the system is configured to switch between a locked mode, in which the rotation of the first member relative to the second member is prevented regardless of the relative rotation direction between the first and second members, and a free mode, in which the rotation of the first member relative to the second member is permitted regardless of the relative rotation direction between the first and second members.

[0034] In a power transmission path switching device according to one aspect of the present disclosure, the cam device is configured with a cam device according to one aspect of the present disclosure.

[0035] One aspect of the present disclosure is a two-speed transmission, Input component and An output member supported to enable relative rotation with respect to the input member, A planetary gear mechanism is disposed between the input member and the output member, The system includes a power transmission path switching device that switches the power transmission path between the input member and the output member.

[0036] In a two-speed transmission according to one aspect of the present disclosure, the power transmission path switching device is comprised of a power transmission path switching device according to one aspect of the present disclosure.

[0037] The planetary gear mechanism comprises a sun gear, a ring gear arranged coaxially with the sun gear around the sun gear, a carrier supported to allow relative rotation between the sun gear and the ring gear, and a plurality of planetary gears that mesh with the sun gear and the ring gear and are supported on the carrier to allow rotation about their own central axis. The input element, which is one of the sun gear, the ring gear, and the carrier, rotates integrally with the input member, or is composed of the input member itself. An output element, which is one of the sun gear, the ring gear, and the carrier and is a separate element from the input element, rotates integrally with the output member, or is composed of the output member itself. The rotating elements of the sun gear, ring gear, and carrier, excluding the input and output elements, rotate integrally with the first clutch member, or are composed of the first clutch member itself. [Effects of the Invention]

[0038] According to one aspect of the cam device, power transmission path switching device, and two-speed transmission of this disclosure, it is possible to prevent the generation of unpleasant noises and vibrations at the engagement portion between the support member and the driven cam when the rotational phase of the drive cam changes. [Brief explanation of the drawing]

[0039] [Figure 1] Figure 1 is a schematic cross-sectional view showing a vehicle drive mechanism incorporating a two-speed transmission according to a first example of the embodiments of this disclosure. [Figure 2]Figure 2(A) shows the torque transmission path in the reduced gear ratio mode of the two-speed transmission for the first example, and Figure 2(B) shows the torque transmission path in the high reduction ratio mode of the two-speed transmission for the first example. [Figure 3] Figure 3 is a cross-sectional view showing a two-speed transmission in the first example. [Figure 4] Figure 4 is a cross-sectional view of the power transmission path switching device for the first example. [Figure 5] Figure 5 is an exploded perspective view showing the power transmission path switching device for the first example. [Figure 6] Figure 6 is an enlarged view of section A in Figure 4. [Figure 7] Figure 7 is an exploded perspective view showing the cam mechanism for the first example. [Figure 8] Figure 8 is a perspective view showing the drive cam for the first example. [Figure 9] Figure 9 is an exploded perspective view of the first example, showing the driven cam, multiple rolling elements, and side members. [Figure 10] Figures 10(A) to 10(D) are schematic diagrams showing a part of the cam mechanism viewed from the radially outer direction. [Figure 11] Figures 11(A) and 11(B) schematically show the cam mechanism for the first example. [Figure 12] Figure 12 is a perspective view of the rotational transmission state switching device for the first example, seen from the left side of Figure 4. [Figure 13] Figure 13 is an exploded perspective view showing the rotational transmission state switching device for the first example. [Figure 14] Figure 14 is an end view of the first example, showing the rotation transmission state switching device with the cover removed, viewed from the left side of Figure 4. [Figure 15] Figure 15 is an enlarged view of section B in Figure 14. [Figure 16]Figure 16(A) is a schematic diagram showing the engagement relationship between the first and second engaging claws, the engaging recess, and the projection in the free mode of the rotation transmission state switching device in the first example; Figure 16(B) is a schematic diagram showing the engagement relationship in the locked mode; and Figure 16(C) is a schematic diagram showing the engagement relationship in the one-way clutch mode. [Figure 17] Figure 17 is a schematic diagram illustrating the modes of the electric friction clutch device and the rotational transmission state switching device in the power transmission path switching device for the first example. [Figure 18] Figure 18 is a schematic diagram of the engagement portion between the driven cam and the side member, as viewed from the radially outer side, for a second example of an embodiment of the present disclosure. [Figure 19] Figure 19 is a schematic diagram of the engagement portion between the driven cam and the side member, viewed from the radially outer side, for a third example of an embodiment of the present disclosure. [Figure 20] Figure 20 is a schematic diagram of the engagement portion between the driven cam and the side member, viewed from the radially outer side, for a fourth example of the embodiment of the present disclosure. [Figure 21] Figure 21 is a diagram showing the time evolution of each parameter when switching a two-speed transmission from a reduced gear ratio mode to a high reduction ratio mode in a conventional electric vehicle drive system. [Modes for carrying out the invention]

[0040] [Example 1] A first example of the embodiment of this disclosure will be described with reference to Figures 1 to 17.

[0041] This example shows a cam mechanism according to one embodiment of the present disclosure incorporated into a two-speed transmission 1. The two-speed transmission 1 is positioned between an electric motor 2, which is the power source of an electric vehicle or hybrid vehicle, and a differential 3, and transmits the output torque of the electric motor 2 to the differential 3 either while increasing (decelerating) it or without increasing it.

[0042] However, the cam device according to one aspect of this disclosure is not limited to a two-speed transmission, but can be incorporated into various mechanical devices and used for purposes such as switching the operating mode of the mechanical device.

[0043] The two-speed transmission 1 comprises an input member 4, an output member 5, a planetary gear mechanism 6, and a power transmission path switching device 7.

[0044] With respect to the two-speed transmission 1, the axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions of the input member 4, unless otherwise specified. The axial, radial, and circumferential directions of the input member 4 coincide with the axial, radial, and circumferential directions of the output member 5. Furthermore, one axial side refers to the right side in Figures 1 to 4, and the other axial side refers to the left side in Figures 1 to 4.

[0045] The input member 4 is capable of transmitting torque to the output shaft 8 of the electric motor 2. Specifically, the input member 4 has an input gear 10 at one end on the axial side that meshes with a drive gear 9 provided on the output shaft 8.

[0046] In this example, the input member 4 is rotatably supported by rolling bearings (not shown) or the like, in relation to a fixed part 11 that does not rotate during use, which is made up of a housing that accommodates the two-speed transmission 1. Furthermore, the input member 4 is configured to be cylindrical (hollow).

[0047] The output member 5 is supported in a way that allows for relative rotation with respect to the input member 4.

[0048] In this example, the output member 5 is arranged coaxially with the input member 4 and is supported radially inside the cylindrical input member 4 via rolling bearings (not shown) or the like, allowing for relative rotation with respect to the input member 4. The output member 5 has an output gear 12 at one end on its axial side. The output gear 12 meshes with a ring gear 13 provided at the input of the differential 3. That is, the output member 5 is connected to the input of the differential 3 in a way that allows for the transmission of torque. The rotational torque of the output member 5 is distributed to a pair of drive wheels 14 via the differential 3.

[0049] The planetary gear mechanism 6 includes a sun gear 15, a ring gear 16, a carrier 17, and a plurality of planetary gears 18.

[0050] The ring gear 16 is positioned around the sun gear 15, coaxially with the sun gear 15.

[0051] The carrier 17 is supported coaxially with the sun gear 15 and the ring gear 16, and is capable of relative rotation with respect to the sun gear 15 and the ring gear 16.

[0052] Multiple planetary gears 18 mesh with the sun gear 15 and the ring gear 16, and are supported by the carrier 17, enabling them to rotate (spin) around their own central axis.

[0053] Each of the multiple planetary gears 18 can be composed of a planetary gear that meshes with both the sun gear 15 and the ring gear 16. In other words, the planetary gear mechanism 6 can be composed of a single-pinion type planetary gear mechanism. Alternatively, each of the multiple planetary gears 18 can have a first planetary gear that meshes with the sun gear 15 and a second planetary gear that meshes with the ring gear and also meshes with the first planetary gear. In other words, the planetary gear mechanism 6 can be composed of a double-pinion type planetary gear mechanism.

[0054] In the two-speed transmission 1, the input member 4, output member 5, electric friction clutch device 19, and rotational transmission state switching device 20 are connected to the sun gear 15, ring gear 16, carrier 17, or fixed part 11 so that the reduction ratio between the input member 4 and the output member 5 can be switched between two stages, high and low, by switching the mode of the electric friction clutch device 19 and the rotational transmission state switching device 20 that constitute the power transmission path switching device 7.

[0055] Specifically, an input element, which is one of the sun gear 15, ring gear 16, and carrier 17, rotates integrally with the input member 4, or is composed of the input member 4 itself. An output element, which is one of the sun gear 15, ring gear 16, and carrier 17, and is a different element from the input element, rotates integrally with the output member 5, or is composed of the output member 5 itself. Furthermore, the rotating elements, which are the remaining elements of the sun gear 15, ring gear 16, and carrier 17 excluding the input element and the output element, rotate integrally with the first clutch member 21 provided in the power transmission path switching device 7, or are composed of the first clutch member 21 itself.

[0056] For example, the ring gear 16 may rotate integrally with the input member 4, or be composed of the input member 4 itself; the carrier 17 may rotate integrally with the output member 5, or be composed of the output member 5 itself; and the sun gear 15 may rotate integrally with the first clutch member 21, or be composed of the first clutch member 21 itself.

[0057] Alternatively, the sun gear 15 may rotate integrally with the input member 4, or be composed of the input member 4 itself; the carrier 17 may rotate integrally with the output member 5, or be composed of the output member 5 itself; and the ring gear 16 may rotate integrally with the first clutch member 21, or be composed of the first clutch member 21 itself.

[0058] Alternatively, the sun gear 15 may rotate integrally with the input member 4, or be composed of the input member 4 itself; the ring gear 16 may rotate integrally with the output member 5, or be composed of the output member 5 itself; and the carrier 17 may rotate integrally with the first clutch member 21, or be composed of the first clutch member 21 itself.

[0059] In this example, the ring gear 16 rotates integrally with the input member 4, or is composed of the input member 4 itself; the carrier 17 rotates integrally with the output member 5, or is composed of the output member 5 itself; and the sun gear 15 rotates integrally with the first clutch member 21, or is composed of the first clutch member 21 itself.

[0060] More specifically, the sun gear 15 is provided at one axial end of the first clutch member 21.

[0061] The ring gear 16 is located in the axial middle portion of the input member 4.

[0062] The carrier 17 is integrated with the output component 5.

[0063] Furthermore, each of the multiple planetary gears 18 meshes with both the sun gear 15 and the ring gear 16, and is supported by the carrier 17 so that it can rotate (spin) around its own central axis. In other words, in this example, the planetary gear mechanism 6 is composed of a single-pinion type planetary gear mechanism.

[0064] The power transmission path switching device 7 comprises an electric friction clutch device 19 and a rotation transmission state switching device 20.

[0065] The electric friction clutch device 19 includes a first clutch member 21, a second clutch member 22, a friction engagement portion 23, a cam device 24, and an electric actuator 25. The electric friction clutch device 19 switches between a connection mode in which torque is transmitted between the first clutch member 21 and the second clutch member 22, and a disconnection mode in which torque is not transmitted.

[0066] The first clutch member 21 is supported coaxially with the input member 4 and the output member 5, and is capable of relative rotation with respect to the input member 4 and the output member 5. In this example, the first clutch member 21 is rotatably supported with respect to the fixed portion 11 by a cam device 24 and radial bearing 49, which constitute the electric friction clutch device 19.

[0067] In this example, the first clutch member 21 has a locking groove 26 extending around its entire circumference on the outer circumferential surface of its axial intermediate portion.

[0068] In this example, the first clutch member 21 has a flange portion 27 that protrudes radially outward in the portion located on the axial side other than the locking groove 26.

[0069] The flange portion 27 has a hollow circular plate-shaped ring portion 28 and a cylindrical portion 29 that is bent axially from the radially outer end of the ring portion 28 toward the other side.

[0070] The ring portion 28 has through holes 30 that penetrate axially at multiple locations in the circumferential direction in the radially intermediate portion.

[0071] In this example, the first clutch member 21 is constructed by connecting and fixing the shaft member 31 and the flange element 27a.

[0072] The shaft member 31 has a stepped cylindrical shape. Specifically, the shaft member 31 has, in order from one side in the axial direction, a first small diameter cylindrical portion 32, a large diameter cylindrical portion 33, a medium diameter cylindrical portion 34, and a second small diameter cylindrical portion 35.

[0073] The locking groove 26 is formed around the entire circumference of the outer circumferential surface of one axial side portion of the large-diameter cylindrical portion 33.

[0074] In this example, the large-diameter cylindrical portion 33 has a projection 36 extending around its entire circumference at the other end on the axial side, projecting radially outward from the portion adjacent to it on the axial side. The projection 36 has a fitting surface 37 provided on the outer circumferential surface of the portion on the axial side, and a stepped surface 38 that bends radially outward from the other end on the axial side of the fitting surface 37 and faces the axial side.

[0075] The flange element 27a has an annular portion 28 and a cylindrical portion 29.

[0076] The shaft member 31 and the flange element 27a are joined and fixed together by welding or the like, with the radially inner portion of the other axial side surface of the ring portion 28 in contact with the stepped surface 38, and the inner circumferential surface of the ring portion 28 fitted onto the fitting surface portion 37.

[0077] The second clutch member 22 is supported coaxially with the first clutch member 21, allowing for relative rotation with respect to the first clutch member 21. Furthermore, the second clutch member 22 is connected to the input member 4 or the output member 5 so as to rotate integrally with it, or it is composed of the input member 4 or the output member 5 itself. In this example, the second clutch member 22 is composed of the input member 4 itself. In other words, the input member 4 and the second clutch member 22 are integrally configured.

[0078] The friction engagement portion 23 has at least one first friction plate 39 and at least one second friction plate 40, which are supported to allow relative axial displacement, and is provided between the first clutch member 21 and the second clutch member 22.

[0079] In this example, at least one first friction plate 39 is composed of multiple first friction plates 39, and at least one second friction plate 40 is composed of multiple second friction plates 40. Specifically, the friction engagement portion 23 is composed of a multi-plate clutch in which multiple first friction plates 39 supported by a first clutch member 21 and multiple second friction plates 40 supported by a second clutch member 22 are alternately stacked.

[0080] More specifically, the multiple first friction plates 39 are supported on the outer circumferential surface of one axial side portion of the cylindrical portion 29 constituting the first clutch member 21, in such a way that they can be displaced axially but cannot rotate relative to the cylindrical portion 29.

[0081] Multiple second friction plates 40 are supported on the inner circumferential surface of the other axial end of the second clutch member 22 (input member 4) in such a way that they can be displaced in the axial direction, but cannot rotate relative to the second clutch member 22.

[0082] In this example, the friction plate located furthest to the other axial direction among the first friction plate 39 and the second friction plate 40 is prevented from being displaced to the other axial direction by abutting its side surface on the other axial direction against the side surface on one axial direction of an annular retaining member 116 that is fitted and fixed to the axial middle portion of the cylindrical portion 29.

[0083] The cam device 24 includes a drive cam 41 and a driven cam 42 that is supported to allow relative rotation and relative axial displacement with respect to the drive cam 41, and expands and contracts the axial distance between the drive cam 41 and the driven cam 42 as the drive cam 41 rotates.

[0084] The cam mechanism 24 further includes a drive cam 41 and a driven cam 42, as well as a support member 43, a side member 44, and a biasing member 45. Figures 11(A) and 11(B) are schematic diagrams of the cam mechanism 24.

[0085] The support member 43 has a support member-side engaging portion 46.

[0086] The support member 43 is supported and fixed to the fixed portion 11. The structure of the support member 43 is not limited as long as it can support the drive cam 41 so that it can rotate relative to it but cannot be displaced relative to it in the axial direction, and can support the driven cam 42 and the support member 43 so that they can be displaced relative to it in the axial direction but their relative rotation is restricted. In this example, the support member 43 has a cylindrical portion 47 and an outward-facing flange portion 48 extending radially outward from the other axial end of the cylindrical portion 47. In this example, the support member-side engaging portion 46 is made up of a male spline portion provided on the outer circumferential surface of the axial portion of the cylindrical portion 47. In this example, the support member 43 is supported and fixed to the fixed portion 11 by the outward-facing flange portion 48 by screws or the like.

[0087] In this example, the support member 43 supports the first clutch member 21 so that it can rotate relative to the support member 43, but so that it cannot be displaced in the axial direction, by a radial bearing 49. The radial bearing 49 has an inner ring 50 fitted and fixed to the second small diameter cylindrical portion 35 of the first clutch member 21, an outer ring 51 fitted and fixed to the cylindrical portion 47 of the support member 43, and a plurality of rolling elements 52 arranged to roll freely between the inner ring 50 and the outer ring 51. In the illustrated example, the radial bearing 49 is made up of a double-row deep groove ball bearing using balls as the rolling elements 52. However, the radial bearing is not particularly limited as long as it can support the rotation of the first clutch member 21 relative to the support member 43 and prevent axial displacement of the first clutch member 21 relative to the support member 43, and can be made up of, for example, a deep groove ball bearing, a radial angular contact ball bearing, or a radial tapered roller bearing.

[0088] The drive cam 41 is supported in a way that allows rotation relative to the support member 43, but prevents axial displacement relative to the support member 43.

[0089] In this example, the drive cam 41 is rotatably supported relative to the support member 43 by an angular contact ball bearing 53. Note that the support member 43 and the angular contact ball bearing 53 are not shown in Figures 1 to 2(B). The angular contact ball bearing 53 has an inner ring 54 fitted and fixed to the cylindrical portion 47 of the support member 43, an outer ring 55 fitted and fixed to the drive cam 41, and a plurality of balls 56 that are rotatably arranged between the inner ring 54 and the outer ring 55.

[0090] The driven cam 42 has a driven cam-side engaging portion 57, and is positioned on one axial side of the drive cam 41 such that the driven cam-side engaging portion 57 is engaged with the support member-side engaging portion 46 so as to allow axial displacement and restrict rotation. As the drive cam 41 rotates, it is displaced axially relative to the support member 43, thereby expanding or contracting the axial distance between the drive cam 41 and the support member 43.

[0091] In this example, the driven cam 42 has a hollow circular plate shape. In this example, the driven cam-side engaging portion 57 is composed of a female spline portion provided on the inner circumferential surface of the driven cam 42. The driven cam 42 is supported so that it can only be displaced axially relative to the fixed portion 11 by spline engaging the driven cam-side engaging portion 57 with the support member-side engaging portion 46 of the support member 43. A small circumferential gap is provided in the spline engaging portion between the support member-side engaging portion 46 and the driven cam-side engaging portion 57 in order to allow smooth axial sliding of the driven cam-side engaging portion 57 relative to the support member-side engaging portion 46.

[0092] The side member 44 has a side member-side engaging portion 68, and is positioned on one axial side of the driven cam 42 with the side member-side engaging portion 68 engaged with the support member-side engaging portion 46 in such a way that it allows axial displacement but restricts rotation.

[0093] In this example, the side member 44 has a hollow circular plate shape with an outer diameter smaller than the outer diameter of the driven cam 42. In this example, the side member-side engaging portion 68 is composed of a female spline portion provided on the inner circumferential surface of the side member 44. The side member 44 is supported so that it can only be displaced axially relative to the fixed portion 11 by spline engaging the side member-side engaging portion 68 with the support member-side engaging portion 46 of the support member 43. A small circumferential gap is provided in the spline engaging portion between the support member-side engaging portion 46 and the side member-side engaging portion 68 to allow smooth axial sliding of the side member-side engaging portion 68 relative to the support member-side engaging portion 46.

[0094] In this example, a spline engagement portion is used as the structure of the engagement portion between the support member-side engagement portion 46, the driven cam-side engagement portion 57, and the side member-side engagement portion 68. However, when implementing this disclosure, a key engagement portion or the like can also be used as the structure of the engagement portion between the support member-side engagement portion, the driven cam-side engagement portion, and the side member-side engagement portion.

[0095] Furthermore, in this example, the support member-side engaging portion 46 is positioned radially inward of the driven cam-side engaging portion 57 and the side member-side engaging portion 68. However, when implementing this disclosure, a configuration in which the support member-side engaging portion is positioned radially outward of the driven cam-side engaging portion and the side member-side engaging portion can also be adopted.

[0096] The biasing member 45 elastically biases the side member 44 toward the other axial direction.

[0097] The structure of the biasing member 45 is not limited as long as it can elastically bias the side member 44 toward the other axial direction. In this example, the biasing member 45 is composed of an elastic member 78 and a preloading member 81. The biasing member 45 elastically biases the driven cam 42 toward the drive cam 41 toward the other axial direction via the side member 44.

[0098] In a cam device 24 that expands and contracts the axial distance between a drive cam 41 and a driven cam 42 as the drive cam 41 rotates, the drive cam 41 has a rotational phase in which the direction of the circumferential component of the force acting from the drive cam 41 to the driven cam 42 is in a predetermined direction, and a second phase in which the direction of the circumferential component of the force acting from the drive cam 41 to the driven cam 42 is in the opposite direction to the predetermined direction.

[0099] The configuration for expanding or contracting the axial distance between the drive cam 41 and the driven cam 42 as the drive cam 41 rotates is arbitrary. For example, a configuration in which the drive cam surface on the drive cam and the driven cam surface on the driven cam slide directly against each other, a configuration in which multiple rolling elements (rollers, balls, etc.) are sandwiched between the drive cam surface on the drive cam and the driven cam surface on the driven cam, or a configuration in which multiple rolling elements (rollers, balls, etc.) supported by one of the cams (drive cam or driven cam) roll into contact with the cam surface on the other cam (drive cam or driven cam).

[0100] In this example, the cam device 24 further comprises a plurality of rolling elements 59 that are supported by the driven cam 42 and that roll in contact with the drive cam surface 58 provided on the drive cam 41.

[0101] In this example, as shown in Figure 8, the drive cam 41 has a drive cam surface 58 on the radially inner portion of one axial side surface, in which equal numbers of recesses and protrusions are alternately arranged in the circumferential direction. As shown in Figures 10(A) to 10(D), the drive cam surface 58 includes a first inclined surface portion (gently inclined surface portion 60b, first moderately inclined surface portion 60f) that is inclined in the direction toward the axial side (right side of Figures 10(A) to 10(D)) as it moves toward one circumferential side (lower side of Figures 10(A) to 10(D)), and a second inclined surface portion (inclined surface portion 60d, second moderately inclined surface portion 60h) that is inclined in the direction toward the axial side as it moves toward the other circumferential side (upper side of Figures 10(A) to 10(D)). In this example, the drive cam surface 58 is arranged in the following order from the other side in the circumferential direction to the one side in the circumferential direction: first bottom portion 60a, gently sloping surface portion 60b, first flat surface portion 60c, inclined surface portion 60d, second bottom portion 60e, first intermediate inclined surface portion 60f, second flat surface portion 60g, and second intermediate inclined surface portion 60h, repeated the same number of times as the number of rolling elements 59 (3 times in this example).

[0102] Of the drive cam surface 58, the first flat surface portion 60c and the second flat surface portion 60g are located furthest to one side in the axial direction, i.e., at the tip of the convex portion, while the first bottom portion 60a and the second bottom portion 60e are located furthest to the other side in the axial direction. The inclination angles of the first intermediate inclined surface portion 60f and the second intermediate inclined surface portion 60h with respect to the circumferential direction (a virtual plane P perpendicular to the central axis of the drive cam 41) are greater than the inclination angle of the gently inclined surface portion 60b with respect to the circumferential direction.

[0103] The inclination angle of the gently sloping surface 60b, and the inclination angles of the first intermediate inclined surface 60f and the second intermediate inclined surface 60h are all set to a size that allows the rolling element 59 to move either by rolling down or by riding over it. In this example, the first intermediate inclined surface 60f and the second intermediate inclined surface 60h have opposite inclination directions and the same inclination angles, but the inclination angles can also be made different. In this example, the inclination angle of the gently sloping surface 60b is smaller than the inclination angles of the first intermediate inclined surface 60f and the second intermediate inclined surface 60h, but the inclination angle of the gently sloping surface 60b and the inclination angles of the first intermediate inclined surface 60f and the second intermediate inclined surface 60h can also be made the same.

[0104] Furthermore, the inclination angle of the inclined surface portion 60d with respect to the circumferential direction can be set to any size as long as the rolling element 59 can ride over it.

[0105] In this example, the drive cam 41 has wheel teeth 61, which are helical gears, on its outer circumferential surface, and has pin portions 62 that protrude toward the axial direction at multiple locations (three locations in the illustrated example) in the circumferential direction in the radial middle of one side of the axial surface.

[0106] In this example, as shown in Figure 9, the driven cam 42 has rectangular holes 63 that penetrate axially at multiple locations (three locations in the illustrated example) in the circumferential direction in the radially intermediate part, and each rectangular hole 63 has support plate portions 64a and 64b on both radial sides. The radially outer support plate portion 64a has a support hole 65a which is a circular hole that penetrates radially. The radially inner support plate portion 64b has a support hole 65b which is a circular hole that penetrates radially.

[0107] In this example, the multiple rolling elements 59 are composed of three rolling elements 59. However, the multiple rolling elements 59 can also be composed of two or four or more rolling elements 59.

[0108] In this example, the rolling element 59 has a cylindrical shape. That is, the rolling element 59 is composed of rollers. The rolling element 59 is supported to rotate freely on the support plate portions 64a and 64b via a cylindrical support shaft 66 and a plurality of rollers 67. That is, the axial ends on both sides of the support shaft 66 are fitted and fixed in the support holes 65a and 65b. The plurality of rollers 67 are sandwiched between the inner circumferential surface of the rolling element 59 and the outer circumferential surface of the axial intermediate portion of the support shaft 66 so as to be able to roll freely. As a result, the rolling element 59 is supported by the driven cam 42 to rotate freely on its axis of rotation C, which is oriented radially from the central axis of the driven cam 42.

[0109] With the rolling element 59 supported by the driven cam 42, one axial portion of the rolling element 59 is positioned inside the rectangular hole 63. The outer circumferential surface of the rolling element 59 is in rolling contact with the drive cam surface 58 provided on the other axial side of the drive cam 41.

[0110] The cam device 24 rotates the drive cam 41 and increases or decreases the amount by which the rolling elements 59 ride up from the first bottom 60a or the second bottom 60e of the drive cam surface 58, thereby moving the driven cam 42 in the axial direction and expanding or contracting the axial distance between the drive cam 41 and the driven cam 42, i.e., the axial dimension of the cam device 24.

[0111] In this example, as shown in Figure 11(A), as the drive cam 41 rotates, the multiple rolling elements 59 supported by the driven cam 42 move while rolling circumferentially along the first inclined surface (gently inclined surface 60b or first intermediate inclined surface 60f). In the phase of the drive cam 41, the force F1 acting on the multiple rolling elements 59 from the first inclined surface (gently inclined surface 60b or first intermediate inclined surface 60f) can be decomposed into an axial component fa1 directed in one axial direction and a circumferential component fc1 directed in the other circumferential direction. In other words, as the drive cam 41 rotates, the rotational phase of the drive cam 41 when the multiple rolling elements 59 supported by the driven cam 42 move circumferentially along the first inclined surface (gently inclined surface 60b or first moderately inclined surface 60f) is the first phase in which the direction of the circumferential component of the force acting from the drive cam 41 on the driven cam 42 is in a predetermined direction (the other side of the drive cam surface 58 in the circumferential direction).

[0112] In contrast, as shown in Figure 11(B), in the phase of the drive cam 41 when the multiple rolling elements 59 supported by the driven cam 42 move while rolling circumferentially along the second inclined surface (inclined surface 60d or second intermediate inclined surface 60h) as the drive cam 41 rotates, the force F2 acting on the multiple rolling elements 59 from the second inclined surface (inclined surface 60d or second intermediate inclined surface 60h) can be decomposed into an axial component fa2 that is directed in one direction in the axial direction and a circumferential component fc2 that is directed in one direction in the circumferential direction. In other words, as the drive cam 41 rotates, the rotational phase of the drive cam 41 is such that the direction of the circumferential component of the force acting from the drive cam 41 on the drive cam 42 is opposite to the predetermined direction (one side of the circumferential direction of the drive cam surface 58).

[0113] The side member 44 applies a rotation-restricting force to the driven cam 42 having a circumferential component in the predetermined direction, based on the biasing force of the biasing member 45. The magnitude of the torque based on the circumferential component of the rotation-restricting force is greater than the magnitude of the torque based on the circumferential component of the force acting from the drive cam 41 to the driven cam 42 in the second phase.

[0114] The configuration in which the side member 44 applies the rotational restricting force to the driven cam 42 based on the biasing force of the biasing member 45 is arbitrary. For example, a configuration in which the receiving preload cam surface on the driven cam 42 and the pushing preload cam surface on the side member 44 are in direct contact, a configuration in which an engaging element is sandwiched between the receiving preload cam surface on the driven cam 42 and the pushing preload cam surface on the side member 44, and a configuration in which an engaging element (roller, ball, etc.) supported on one of the driven cam 42 and the side member 44 is in contact with the preload cam surface on the other of the driven cam 42 and the side member 44.

[0115] In this example, the cam device 24 has a configuration in which the receiving side preload cam surface 69 provided on the driven cam 42 and the pushing side preload cam surface 70 provided on the side member 44 are in direct contact.

[0116] In this example, the receiving preload cam surface 69 is provided on the radially inner portion of one axial side surface of the driven cam 42. The number of receiving preload cam surfaces 69 and the phase of their circumferential arrangement are not particularly limited. In this example, the receiving preload cam surface 69 is composed of three receiving preload cam surfaces 69, each receiving preload cam surface 69 positioned circumferentially adjacent to the radially inner side of the rectangular hole 63.

[0117] Each receiving-side preload cam surface 69 is composed of an inclined surface that is inclined in the same direction as the second inclined surface portion (inclined surface portion 60d, second intermediate inclined surface portion 60h) that constitutes the driving cam surface 58 with respect to the circumferential direction, that is, an inclined surface that is inclined in a direction toward one side in the axial direction as it moves toward the other side in the circumferential direction. In this example, the inclination angle of the receiving-side preload cam surface 69 with respect to the circumferential direction is set to a larger value than the inclination angle of the second inclined surface portion (inclined surface portion 60d, second intermediate inclined surface portion 60h) with respect to the circumferential direction. In this example, the portions of the side surface of the driven cam 42 on one side in the axial direction that are adjacent to both sides of the receiving-side preload cam surface 69 in the circumferential direction are each composed of flat surfaces perpendicular to the axial direction. The portion of the side surface of the driven cam 42 on one side in the axial direction that is adjacent to the other side of the receiving-side preload cam surface 69 in the circumferential direction is located further toward one side in the axial direction than the portion adjacent to one side of the receiving-side preload cam surface 69 in the circumferential direction.

[0118] In this example, the push-side preload cam surface 70 is provided on the side surface of the side member 44 on the other axial side. The push-side preload cam surface 70 is composed of the same number of push-side preload cam surfaces 70 as the receiving-side preload cam surfaces 69 (3 in this example), and the phase of the arrangement of the push-side preload cam surfaces 70 and the receiving-side preload cam surfaces 69 in the circumferential direction coincides with each other. The push-side preload cam surface 70 is inclined with respect to the circumferential direction by the same angle as the receiving-side preload cam surface 69 and is in surface contact with the receiving-side preload cam surface 69. In this example, the portions of the side surface of the side member 44 on the other axial side that are adjacent to both sides of the push-side preload cam surface 70 in the circumferential direction are each composed of flat surfaces perpendicular to the axial direction. The portion of the side surface of the side member 44 on the other axial side that is adjacent to the other side of the push-side preload cam surface 70 in the circumferential direction is located on the one axial side than the portion adjacent to one side of the push-side preload cam surface 70 in the circumferential direction.

[0119] The side member 44 applies a rotational restricting force having a circumferential component in the predetermined direction to the driven cam 42 by pressing the pushing-side preload cam surface 70 against the receiving-side preload cam surface 69 based on the biasing force of the biasing member 45.

[0120] In other words, as shown in Figures 11(A) and 11(B), the rotational restricting force F3 applied from the pushing-side preload cam surface 70 to the receiving-side preload cam surface 69 based on the biasing force of the biasing member 45 can be decomposed into an axial component fa3 that is directed in the other axial direction and a circumferential component fc3 that is directed in the other circumferential direction (the predetermined direction).

[0121] Furthermore, in this example, by setting the inclination angle of the receiving preload cam surface 69 with respect to the circumferential direction to a value greater than the inclination angle of the second inclined surface portion (inclined surface portion 60d, second intermediate inclined surface portion 60h) with respect to the circumferential direction, in the second phase of the drive cam 41 shown in Figure 11(B), the magnitude of the circumferential component fc3 of the rotation restricting force F3 acting on the drive cam 42 from the side member 44 is made greater than the magnitude of the circumferential component fc2 of the force F2 acting on the drive cam 41 from the drive cam 41 that is oriented in the opposite direction to the predetermined direction. As a result, the magnitude of the torque based on the circumferential component fc3 of the rotation restricting force F3 (torque in the predetermined direction) is made greater than the magnitude of the torque based on the circumferential component fc2 of the force F2 acting on the drive cam 42 from the drive cam 41 in the second phase (torque in the opposite direction to the predetermined direction).

[0122] Therefore, in the cam device 24, the direction of the total torque, which is the sum of the torque based on the circumferential component of the force acting from the drive cam 41 to the driven cam 42 and the torque based on the circumferential component of the force acting from the side member 44 to the driven cam 42, is always in the predetermined direction, regardless of the phase of rotation of the drive cam 41.

[0123] Therefore, in the cam device 24, as shown in Figures 11(A) and 11(B), regardless of the rotational phase of the drive cam 41, the other circumferential side surface of the teeth 57a of the driven cam-side engaging portion 57 provided on the driven cam 42 always contacts the one circumferential side surface of the teeth 46a of the support member-side engaging portion 46 provided on the support member 43, and the one circumferential side surface of the teeth 57a of the driven cam-side engaging portion 57 and the other circumferential side surface of the teeth 46a of the support member-side engaging portion 46 face each other with a small gap in between.

[0124] Therefore, even when the rotational phase of the drive cam 41 switches from the first phase shown in Figure 11(A) to the second phase shown in Figure 11(B), or from the second phase to the first phase, it is possible to prevent the driven cam 42 from rotating relative to the support member 43 by the amount of the minute circumferential gap present in the spline engagement portion between the driven cam-side engagement portion 57 and the support member-side engagement portion 46. Consequently, it is possible to prevent the teeth 57a of the driven cam-side engagement portion 57 and the teeth 46a of the support member-side engagement portion 46 from colliding with each other and generating unpleasant noises and vibrations known as tooth noise.

[0125] In this example, in order to make the magnitude of the torque based on the circumferential component fc3 of the rotational restricting force F3 greater than the magnitude of the torque based on the circumferential component fc2 of the force F2 acting from the drive cam 41 to the driven cam 42 in the second phase, the inclination angle of the receiving preload cam surface 69 with respect to the circumferential direction is set to a value greater than the inclination angle of the second inclined surface portion (inclined surface portion 60d, second intermediate inclined surface portion 60h) with respect to the circumferential direction, thereby making the magnitude of the circumferential component fc3 greater than the magnitude of the torque based on the circumferential component fc2. However, the magnitude of the torque is calculated as the circumferential component of the force × the length of the arm (the radius of rotation at the point where the circumferential component is acting). Therefore, when implementing this disclosure, if the radius of rotation at the location where the circumferential component fc3 is acting is greater than the radius of rotation at the location where the circumferential component fc2 is acting, by setting the inclination angle of the receiving preload cam surface 69 with respect to the circumferential direction to be less than or equal to the inclination angle of the second inclined surface portion (inclined surface portion 60d, second intermediate inclined surface portion 60h) with respect to the circumferential direction, it may be possible to make the magnitude of the torque based on the circumferential component fc3 greater than the magnitude of the torque based on the circumferential component fc2, even if the magnitude of the circumferential component fc3 is set to be less than or equal to the magnitude of the circumferential component fc2.

[0126] Furthermore, in the cam device 24, a circumferential component in the opposite direction to the predetermined direction acts on the side member 44 from the driven cam 42 as a reaction force to the circumferential component fc3 in the predetermined direction. Therefore, as shown in Figures 11(A) and 11(B), regardless of the rotational phase of the drive cam 41, one circumferential side surface of the teeth 68a of the side member-side engaging portion 68 provided on the side member 44 always contacts the other circumferential side surface of the teeth 46a of the support member-side engaging portion 46 provided on the support member 43, and a state is maintained in which the other circumferential side surface of the teeth 68a of the side member-side engaging portion 68 and the one circumferential side surface of the teeth 46a of the support member-side engaging portion 46 face each other with a small gap between them.

[0127] Therefore, even when the rotational phase of the drive cam 41 switches from the first phase shown in Figure 11(A) to the second phase shown in Figure 11(B), or from the second phase to the first phase, the side member 44 does not rotate relative to the support member 43 by the amount of the minute circumferential gap present in the spline engagement portion between the side member-side engagement portion 68 and the support member-side engagement portion 46. Consequently, at this time, the sides of the teeth 68a of the side member-side engagement portion 68 and the teeth 46a of the support member-side engagement portion 46 do not collide, preventing the generation of unpleasant noises and vibrations known as tooth-clapping noises. This prevents any discomfort to the driver.

[0128] The electric actuator 25 has a shift motor 71 and a reduction gear 72, and the shift motor 71 rotates the drive cam 41 of the cam device 24 via the reduction gear 72.

[0129] In this example, the reduction gear 72 is composed of a worm gear reduction gear. Specifically, the reduction gear 72 is formed by meshing the worm teeth on the outer circumferential surface of a worm 117 connected to the output shaft of the shift motor 71 with the wheel teeth 61 on the outer circumferential surface of a drive cam 41. The worm 117 is rotatably supported relative to the fixed part 11 by a pair of support bearings 73a and 73b. However, the reduction gear 72 can also be composed by meshing a spur gear or bevel gear on the output shaft of the electric motor with a spur gear or bevel gear on the drive cam, or by stretching a belt or chain between the output shaft of the shift motor and the drive cam.

[0130] The electric friction clutch device 19 is configured to switch between a connection mode, in which torque is transmitted between the first clutch member 21 and the second clutch member 22 by pressing the first friction plate 39 and the second friction plate 40 against each other based on expanding or contracting the axial distance between the drive cam 41 and the driven cam 42, and a disconnection mode, in which torque is not transmitted between the first clutch member 21 and the second clutch member 22 by releasing the force pressing the first friction plate 39 and the second friction plate 40 against each other.

[0131] In this example, the electric actuator 25 rotates the drive cam 41, and the first friction plate 39 and the second friction plate 40 are pressed against each other based on the reduction of the axial distance between the drive cam 41 and the driven cam 42. The force pressing the first friction plate 39 and the second friction plate 40 against each other is released based on the increase in the axial distance between the drive cam 41 and the driven cam 42.

[0132] The electric friction clutch device 19 may further include, as an optional component, an elastic biasing mechanism 74 provided between the first clutch member 21 or the second clutch member 22 and the friction engagement portion 23, which elastically biases the first friction plate 39 and the second friction plate 40 in a direction that presses them against each other.

[0133] In this case, the electric friction clutch device 19 is configured such that, based on the relative displacement of the driven cam 42 in a direction that increases the axial distance between it and the drive cam 41, the driven cam 42 presses the elastic biasing mechanism 74 in a direction that releases the force pressing the first friction plate 39 and the second friction plate 40 against each other, and based on the relative displacement of the driven cam 42 in a direction that decreases the axial distance between it and the drive cam 41, the elastic biasing mechanism 74 presses the first friction plate 39 and the second friction plate 40 against each other.

[0134] Alternatively, the electric friction clutch device 19 may further include, as an optional component, an elastic biasing mechanism disposed between the friction engagement portion 23 and the driven cam 42, which elastically biases the friction engagement portion 23 and the driven cam 42 in a direction away from each other.

[0135] In this case, the electric friction clutch device 19 is configured such that, based on the relative displacement of the driven cam 42 in a direction that increases the axial distance between it and the drive cam 41, the driven cam 42 presses the first friction plate 39 and the second friction plate 40 against each other via the elastic biasing mechanism 74, and based on the relative displacement of the driven cam 42 in a direction that decreases the axial distance between it and the drive cam 41, the force pressing the first friction plate 39 and the second friction plate 40 against each other is released.

[0136] In this example, the electric friction clutch device 19 is provided between the first clutch member 21 or the second clutch member 22 and the friction engagement portion 23, and includes an elastic biasing mechanism 74 that elastically biases the first friction plate 39 and the second friction plate 40 in a direction that causes them to press against each other.

[0137] In this example, the elastic biasing mechanism 74 includes a retaining ring 75, a retaining ring 76, a piston 77, and an elastic member 78.

[0138] The retaining ring 75 is fitted onto the outer surface of the large-diameter cylindrical portion 33 of the first clutch member 21, specifically on the portion located on the axial side of the locking groove 26, without radial play and allowing for relative axial displacement.

[0139] The retaining ring 76 is locked into the locking groove 26 of the first clutch member 21, preventing the retaining ring 75 from being displaced in one axial direction.

[0140] The piston 77 is supported to allow axial displacement relative to the first clutch member 21. The piston 77 is configured in the shape of a hollow circular plate and is supported around the portion of the first clutch member 21 between the retaining ring 75 and the flange portion 27 in the axial direction, allowing axial displacement relative to the first clutch member 21. The piston 77 has its axial end face on the other axial side of the radially outer portion facing the axial side of either the first friction plate 39 or the second friction plate 40 that is located furthest to the axial side among the first friction plate 39 and the second friction plate 40.

[0141] The elastic member 78 is provided between the first clutch member 21 and the piston 77. In this example, the elastic member 78 is elastically compressed and sandwiched between the side surface of the retaining ring 75, which is prevented from being displaced in one axial direction relative to the first clutch member 21, and the side surface of the piston 77 in one axial direction. That is, the elastic biasing mechanism 74 elastically biases the first friction plate 39 and the second friction plate 40 in a direction that causes them to press against each other, by pressing the first friction plate 39 or the second friction plate 40, which is on the far axial side, toward the other axial direction via the piston 77, due to the force with which the elastic member 78 tries to elastically restore itself.

[0142] The specific configuration of the elastic member is not particularly limited. In this example, the elastic member 78 is composed of at least one disc spring, or two disc springs in the illustrated example. However, the elastic member may also be composed of other elastic members, such as at least one coil spring.

[0143] The electric friction clutch device 19 in this example further includes a thrust bearing 79, a pressing member 80, and a preloading member 81 between the side member 44 of the cam device 24 and the piston 77.

[0144] The thrust bearing 79 is provided between a pressing member 80 positioned opposite the piston 77 and a side member 44 of the cam device 24. The thrust bearing 79 has a pair of raceway rings 82a and 82b, and a plurality of rolling elements 83 that are rotatably arranged between the pair of raceway rings 82a and 82b. Of the pair of raceway rings 82a and 82b, the raceway ring 82b on the axial side is supported and fixed to the side member 44.

[0145] The pressing member 80 has an annular base 84 having a crank-shaped cross-section, and a partial cylindrical portion 85 that protrudes in the axial direction from multiple locations (three locations in the illustrated example) in the circumferential direction of one end of the base 84 on the axial side. The axial raceway 82a of a pair of raceway rings 82a, 82b of the thrust bearing 79 is supported and fixed to the other end of the base 84 on the axial side. The partial cylindrical portion 85 is inserted through the through hole 30 of the first clutch member 21, and the axial end of the partial cylindrical portion 85, which is the tip, faces the radially intermediate portion of the other side surface of the piston 77 on the axial side.

[0146] The preload-applying member 81 is positioned between the pressing member 80 and the first clutch member 21 and applies preload to the thrust bearing 79. The preload-applying member 81 is elastically compressed and sandwiched between the base portion 84 of the pressing member 80 and the other axial side of the large-diameter cylindrical portion 33 that constitutes the first clutch member 21. By attempting to elastically restore itself, the preload-applying member 81 elastically presses the pressing member 80 toward the other axial direction. This applies preload to the thrust bearing 79 and prevents the thrust bearing 79 from falling out from between the side member 44 and the pressing member 80. The elasticity of the preload-applying member 81 is less than the elastic restoring force of the elastic member 78. The preload-applying member 81 can be composed of, for example, an elastic member such as an elastomer such as rubber, one or more disc springs, one or more coil springs, or other springs.

[0147] The electric friction clutch device 19 in this example includes, as an optional component, a return spring (not shown) positioned between the first friction plate 39 and the second friction plate 40, and elastically biasing in a direction that increases the distance between the first friction plate 39 and the second friction plate 40. This ensures that when the force pressing the first friction plate 39 and the second friction plate 40 against each other is released, the first friction plate 39 and the second friction plate 40 are reliably separated. The elasticity of the return spring is less than the elastic restoring force of the elastic member 78.

[0148] In this example, the electric friction clutch device 19 rotates the drive cam 41 with the electric actuator 25, expanding and contracting the axial distance between the drive cam 41 and the driven cam 42, and displacing the piston 77 of the elastic biasing mechanism 74 axially relative to the first clutch member 21, thereby enabling switching between a disconnection mode in which torque is not transmitted between the first clutch member 21 and the second clutch member 22 and a connection mode in which torque is transmitted.

[0149] First, when switching the electric friction clutch device 19 to a disengagement mode in which torque is not transmitted between the first clutch member 21 and the second clutch member 22, the electric actuator 25 rotates the drive cam 41 to position the rolling element 59 on the first flat surface portion 60c or the second flat surface portion 60g of the drive cam surface 58, as shown in Figures 10(B) and 10(D), or to increase the amount that the rolling element 59 rides onto the gently sloping surface portion 60b, the sloping surface portion 60d, the first intermediate sloping surface portion 60f, or the second intermediate sloping surface portion 60h.

[0150] This causes the driven cam 42 to move axially in one direction, which increases the axial distance between it and the drive cam 41. As a result, the piston 77 of the elastic biasing mechanism 74 is pressed axially in one direction via the side member 44, the thrust bearing 79, and the pressing member 80, and the elastic member 78 is elastically compressed. When the elastic member 78 is elastically compressed, the force pressing the first friction plate 39 and the second friction plate 40 against each other decreases and eventually disappears. As a result, the return spring increases the distance between the first friction plate 39 and the second friction plate 40, and the friction engagement portion 23 is disengaged, causing the electric friction clutch device 19 to switch to disengagement mode.

[0151] In contrast, when the electric friction clutch device 19 is switched to a connection mode that transmits torque between the first clutch member 21 and the second clutch member 22, the electric actuator 25 rotates the drive cam 41 to position the rolling element 59 on the first bottom 60a or second bottom 60e of the drive cam surface 58, as shown in Figures 10(A) and 10(C), or to reduce the amount the rolling element rides up onto the gently sloping surface 60b, the sloping surface 60d, the first intermediate sloping surface 60f, or the second intermediate sloping surface 60h.

[0152] This reduces the force pressing the piston 77 of the elastic biasing mechanism 74 toward one axial direction by moving the driven cam 42 toward the other axial direction, which reduces the axial distance between it and the driven cam 41. As a result, mainly due to the elastic restoring force of the elastic member 78, the piston 77, the pressing member 80, the thrust bearing 79, and the side member 44 are pressed toward the other axial direction, and the piston 77 presses the first friction plate 39 or the second friction plate 40, which is closest to the one axial direction, toward the other axial direction. As a result, the first friction plate 39 and the second friction plate 40 press against each other, and the friction engagement portion 23 is connected, causing the electric friction clutch device 19 to switch to the connected mode.

[0153] In this example, when the electric friction clutch device 19 is maintained in the disengagement mode, the shift motor 71 must be continuously energized to prevent the piston 77 from moving in the other axial direction due to the elasticity of the elastic member 78. In contrast, when the electric friction clutch device 19 is maintained in the engagement mode, the elasticity of the elastic member 78 pushes the piston 77 in the other axial direction, causing the first friction plate 39 and the second friction plate 40 to press against each other. Therefore, when the electric friction clutch device 19 is maintained in the engagement mode, it is not necessary to continuously energize the shift motor 71. In other words, the electric friction clutch device 19 in this example is configured as a normally closed type clutch device.

[0154] In this example, as described above, the biasing member 45 constituting the cam device 24 is composed of an elastic member 78 and a preload-applying member 81. In this example, by increasing the axial distance between the drive cam 41 and the driven cam 42, the piston 77 of the elastic biasing mechanism 74 is pressed axially toward one side via the side member 44, thrust bearing 79, and pressing member 80. When the elastic member 78 is elastically compressed, both the elastic member 78 and the preload-applying member 81 elastically bias the side member 44 toward the other axial side. In contrast, by decreasing the axial distance between the drive cam 41 and the driven cam 42, when the piston 77 of the elastic biasing mechanism 74 is not pressed axially toward one side via the side member 44, thrust bearing 79, and pressing member 80, only the preload-applying member 81 elastically biases the side member 44 toward the other axial side.

[0155] The rotation transmission state switching device 20 comprises a first member 86, a second member 87, a mode select member 88, a first claw member 89, a second claw member 90, a first claw biasing member 91, and a second claw biasing member 92.

[0156] The first member 86 has multiple engagement recesses 93 in the circumferential direction.

[0157] The second member 87 is arranged coaxially with the first member 86.

[0158] The mode select member 88 has multiple protrusions 94 at various locations in the circumferential direction that protrude radially or axially, and rotates or is displaced axially as the drive cam 41 rotates.

[0159] The first claw member 89 has a first base portion 95 pivotally supported on the second member 87 and a first engaging claw 96 extending from the first base portion 95 toward the first side in the circumferential direction.

[0160] The second claw member 90 has a second base portion 97 pivotally supported on the second member 87, and a second engaging claw 98 extending from the second base portion 97 toward the second side in the circumferential direction.

[0161] The first claw biasing member 91 elastically biases the first engaging claw 96 in a direction that engages it with the engaging recess 93.

[0162] The second claw biasing member 92 elastically biases the second engaging claw 98 in a direction that engages it with the engaging recess 93.

[0163] One of the first member 86 and the second member 87 is connected to the first clutch member 21 so as to rotate integrally with it, or is formed by the first clutch member 21 itself. The other of the first member 86 and the second member 87 is supported so as not to rotate relative to the fixed part 11, which does not rotate even during use.

[0164] The rotation transmission state switching device 20 is configured to switch between a lock mode in which the rotation of one member relative to the other member is prevented regardless of the relative rotation direction of the one member relative to the other member, based on the rotation or axial displacement of the mode select member 88, a free mode in which the rotation of one member relative to the other member is permitted regardless of the relative rotation direction of the one member relative to the other member, and a one-way clutch mode in which the rotation of one member relative to the other member in a predetermined direction is permitted, and the rotation of one member relative to the other member in the opposite direction to the predetermined direction is prevented.

[0165] Specifically, in lock mode, the protrusion 94 is positioned circumferentially or axially away from the first engaging claw 96 and the second engaging claw 98, and the first engaging claw 96 and the second engaging claw 98 are engaged with the engaging recess 93, thereby preventing the rotation of one member relative to the other member, regardless of the relative rotation direction of one member relative to the other member.

[0166] In free mode, the first engaging claw 96 and the second engaging claw 98 are pressed radially or axially by the protrusion 94 and retracted from the engaging recess 93, thereby allowing the rotation of one member relative to the other member regardless of the relative rotation direction of one member relative to the other member.

[0167] In one-way clutch mode, the protrusion 94 presses only one of the first engaging claws, the first engaging claw 96 and the second engaging claw 98, in the radial or axial direction, retracting it from the engaging recess 93, while engaging the other engaging claw with the engaging recess 93. This allows the first member to rotate in a predetermined direction relative to the other member, and prevents the first member from rotating in the opposite direction relative to the other member.

[0168] In this example, the first member 86 is connected to the first clutch member 21 so as to rotate integrally with it, and the second member 87 is supported so as not to rotate relative to the fixed portion 11, which does not rotate even during use. In addition, the mode select member 88 rotates in conjunction with the rotation of the drive cam 41.

[0169] In this example, the first member 86 has multiple engagement recesses 93 at circumferential locations on its outer surface. Specifically, the first member 86 has a gear-shaped protrusion-recess portion 100 on its outer surface, in which engagement recesses 93 and protrusions 99 are alternately arranged in the circumferential direction.

[0170] Furthermore, the first member 86 has an outer diameter side concave-convex engagement portion 101 on its inner circumferential surface, which has concave and convex portions arranged alternately in the circumferential direction. The first member 86 is supported so as not to be able to rotate relative to the first clutch member 21 by engaging the outer diameter side concave-convex engagement portion 101 with an inner diameter side concave-convex engagement portion 102 provided on the outer circumferential surface of the other axial side portion of the cylindrical portion 29 of the first clutch member 21. In other words, the first member 86 rotates integrally with the first clutch member 21.

[0171] The second member 87 is supported around the first member 86 coaxially with the first member 86 and is capable of relative rotation with respect to the first member 86. That is, the inner circumferential surface of the second member 87 faces the outer circumferential surface of the first member 86, i.e., the tip surface of the convex portion 99, with a gap in between. The second member 87 has an inner diameter side concave-convex engagement portion 103 on its outer circumferential surface, which has concave and convex portions arranged alternately in the circumferential direction. The second member 87 is supported in a way that prevents relative rotation with respect to the fixed portion 11 by engaging the inner diameter side concave-convex engagement portion 103 with an outer diameter side concave-convex engagement portion provided on the inner circumferential surface of the fixed portion 11. That is, the second member 87 does not rotate even when the two-speed transmission 1 is in use.

[0172] The second member 87 comprises a base portion 104 having a rectangular cross-sectional shape, and a cylindrical portion 105 that protrudes around the entire circumference in the axial direction from the radially outer end of one axial side surface of the base portion 104.

[0173] The base portion 104 has multiple (six in the illustrated example) first retaining recesses 106 and second retaining recesses 107 arranged alternately in the circumferential direction.

[0174] Each first retaining recess 106 opens onto the inner circumferential surface and the other axial side of the base 104. Each first retaining recess 106 comprises a spring retaining portion 108a and a base portion 109a. The spring retaining portion 108a has a substantially rectangular opening shape, with its major axis positioned so that it extends radially outward as it approaches one circumferential side (the clockwise front side in Figures 13 to 15) when viewed from the other axial side. The base portion 109a has a substantially circular opening shape when viewed from the other axial side and is positioned adjacent to the other circumferential side (the clockwise rear side in Figures 13 to 15) of the spring retaining portion 108a.

[0175] Each second retaining recess 107 opens onto the inner circumferential surface and the other axial side of the base 104. When viewed from the other axial side, each second retaining recess 107 has a shape symmetrical to the first retaining recess 106 with respect to a virtual plane containing the central axis of the second member 87. That is, each second retaining recess 107 comprises a spring retaining portion 108b and a base portion 109b. The spring retaining portion 108b has a substantially rectangular opening shape, with its major axis positioned in a direction that extends radially outward as it approaches the other circumferential side when viewed from the other axial side. The base portion 109b has a substantially circular opening shape when viewed from the other axial side and is positioned adjacent to one circumferential side of the spring retaining portion 108b.

[0176] The rotation transmission state switching device 20 in this example includes a first engaging member, a first claw member 89, and a second engaging member, a second claw member 90, as well as a first claw biasing member 91 and a second claw biasing member 92. In this example, the rotation transmission state switching device 20 has multiple and equal numbers of each of the first claw member 89 and the second claw member 90, and the first claw biasing member 91 and the second claw biasing member 92.

[0177] The first base portion 95 of each first claw member 89 is configured in a substantially cylindrical shape and is supported (pivoted) on the base portion 109a of the first retaining recess 106 so as to be able to swing about a pivot parallel to the central axis of the second member 87.

[0178] Each first claw member 89 has a first engaging claw 96 which is substantially flat and extends from the first base 95 toward one side in the circumferential direction. The other axial side portion of the first engaging claw 96 is positioned opposite (engaged with) the outer circumferential surface of the annular projection 111 of the mode select member 88, and the one axial side portion is positioned opposite (engaged with) the recessed portion 100 of the first member 86 (allowing engagement and disengagement with the engaging recess 93).

[0179] The second base portion 97 of each second claw member 90 is configured in a substantially cylindrical shape and is supported on the base portion 109b of the second retaining recess 107, allowing it to swing about a pivot parallel to the central axis of the second member 87.

[0180] Each second claw member 90 has a second engaging claw 98 which is substantially flat and extends from the second base 97 toward the other side in the circumferential direction. The second engaging claw 98 has its axial other side facing the outer circumferential surface of the annular projection 111 of the mode select member 88, and its axial one side facing the recessed portion 100 of the first member 86.

[0181] The first claw biasing member 91 applies a biasing force to the first claw member 89 in a direction that causes the first claw member 89 to swing clockwise around the central axis (pivot) of the first base 95 as shown in Figure 15. Specifically, the first claw biasing member 91 is made of an elastic member such as a coil spring and is held in an elastically compressed state between the bottom surface (surface facing radially inward) of the spring holding portion 108a of the first holding recess 106 and the radially outer surface of the first engaging claw 96.

[0182] The second claw biasing member 92 applies a biasing force to the second claw member 90 in a direction that causes the second claw member 90 to swing counterclockwise around the central axis of the second base 97, as shown in Figure 15. Specifically, the second claw biasing member 92 is made of an elastic member such as a coil spring and is held in an elastically compressed state between the bottom surface (the surface facing radially inward) of the spring holding portion 108b of the second holding recess 107 and the radially outer surface of the second engaging claw 98.

[0183] As shown in Figure 13, the mode select member 88 comprises a substantially circular plate-shaped base portion 110 and an annular projection portion 111 that protrudes from the radially intermediate portion of the other axial side surface of the base portion 110 to the other axial side over its entire circumference.

[0184] The base portion 110 has plate-side engagement holes 112 at multiple equally spaced locations in the circumferential direction in the radially intermediate part of the other side of the axial portion (three locations in the illustrated example). The axial end of the pin portion 62 is fitted (engaged) into each plate-side engagement hole 112 without any rattle. In other words, the mode select member 88 rotates integrally with the drive cam 41 (in the same direction and at the same speed).

[0185] The annular projection 111 has multiple projections 94 on its outer surface in the circumferential direction, projecting radially outward. That is, the annular projection 111 has a gear-shaped uneven surface 113 on its outer surface, in which projections 94 and recesses are alternately arranged in the circumferential direction.

[0186] The first member 86 and the second member 87 and the mode select member 88 are combined by the cover 114 and the retaining ring 115 so as to be rotatable relative to each other, but so as not to be displaced relative in the axial direction (to prevent accidental separation in the axial direction), thereby constituting the rotation transmission state switching device 20.

[0187] Specifically, with the first member 86 positioned radially inward of one axial side portion of the base 104 of the second member 87, a ring-shaped cover 114 is supported and fixed to one axial side of the second member 87 by screws, and the other axial side of the radially inward portion of the cover 114 is positioned opposite one axial side of the first member 86. This prevents the first member 86 from being displaced in one axial direction relative to the second member 87.

[0188] The annular projection 111 of the mode select member 88 is positioned radially inward of the other axial side portion of the base 104 of the second member 87, the tip surface (side surface on one axial side) of the annular projection 111 is in sliding contact or close proximity to the other axial side portion of the first member 86, and the side surface on one axial side of the radially outer portion of the base 110 is in sliding contact or close proximity to the other axial side portion of the base 104 of the second member 87, while the retaining ring 115 is locked to the other axial end of the inner circumferential surface of the cylindrical portion 105 of the second member 87. This prevents the first member 86 and the mode select member 88 from being displaced in the other axial direction relative to the second member 87.

[0189] The rotation transmission state switching device 20 in this example is configured to switch between free mode, locked mode, and one-way clutch mode by switching the engagement state between the first engaging claw 96 of the first claw member 89 and the engaging recess 93 of the first member 86, and the engagement state between the second engaging claw 98 of the second claw member 90 and the engaging recess 93, based on the rotation of the mode select member 88.

[0190] In free mode, the circumferential phase of the mode select member 88 relative to the second member 87 is adjusted, and as shown in Figure 16(A), the projection 94 pushes the first engaging claw 96 radially outward against the elasticity of the first claw biasing member 91, and pushes the second engaging claw 98 radially outward against the elasticity of the second claw biasing member 92. As a result, the engagement between the engaging recess 93 of the first member 86 and the first engaging claw 96 and the second engaging claw 98 is disengaged. In this state, rotation of the first member 86 relative to the second member 87 is permitted regardless of the relative rotation direction of the first member 86 and the second member 87. That is, rotation of the first member 86 relative to the fixed portion 11 is permitted regardless of the rotation direction of the first member 86.

[0191] In lock mode, the circumferential phase of the mode select member 88 relative to the second member 87 is adjusted so that the protrusion 94 is positioned circumferentially away from the first engaging claw 96 of the first claw member 89 and the second engaging claw 98 of the second claw member 90, as shown in Figure 16(B). That is, the phase of the recess of the uneven portion 113 is aligned with that of the first engaging claw 96 and the second engaging claw 98 with respect to the circumferential direction. As a result, the engaging recess 93 of the first member 86 engages with the first engaging claw 96 and the second engaging claw 98. In this state, regardless of the relative rotation direction of the first member 86 and the second member 87, rotation of the first member 86 relative to the second member 87 is prevented. That is, regardless of the rotation direction of the first member 86, rotation of the first member 86 relative to the fixed portion 11 is prevented.

[0192] In one-way clutch mode, the circumferential phase of the mode select member 88 relative to the second member 87 is adjusted, and as shown in Figure 16(C), the projection 94 pushes only the second engaging claw 98 radially outward against the elasticity of the second claw biasing member 92. As a result, the engaging recess 93 of the first member 86 engages with the first engaging claw 96, and the engagement between the engaging recess 93 and the second engaging claw 98 is disengaged. In this state, only rotation of the first member 86 relative to the second member 87 in the predetermined direction (clockwise in Figure 16(C)) is permitted, and rotation in the opposite direction (counterclockwise in Figure 16(C)) is prevented.

[0193] In other words, when the first member 86 attempts to rotate relative to the second member 87 in the predetermined direction, the protrusion 99 of the uneven portion 100 pushes the first engaging claw 96 radially outward against the elasticity of the first claw biasing member 91. As a result, rotation of the first member 86 in the predetermined direction is permitted. Conversely, when the first member 86 attempts to rotate relative to the second member 87 in the opposite direction to the predetermined direction, the engagement between the engaging recess 93 and the first engaging claw 96 prevents the first member 86 from rotating in the opposite direction. In short, the rotation transmission state switching device 20 operates as a ratchet-type one-way clutch.

[0194] The predetermined direction mentioned above coincides with the forward rotation direction of the input member 4. The forward rotation direction of the input member 4 refers to the direction of rotation of the input member 4 when the automobile is moved forward.

[0195] The two-speed transmission 1 is configured to switch between a high reduction ratio mode, in which the reduction ratio between the input member 4 and the output member 5 is large, and a low reduction ratio mode, in which the reduction ratio between the input member 4 and the output member 5 is small, by switching the mode of the electric friction clutch device 19 and the rotation transmission state switching device 20. Furthermore, the two-speed transmission 1 is configured to pass through a reduction ratio switching mode during the switching from the high reduction ratio mode to the low reduction ratio mode.

[0196] <Reduced Speed ​​Ratio Mode> To switch the two-speed transmission 1 to the reduced gear ratio mode, the electric friction clutch device 19 is switched to the connected mode, and the rotational transmission state switching device 20 is switched to the free mode.

[0197] Specifically, the electric actuator 25 rotates the drive cam 41, reducing the axial distance between the drive cam 41 and the driven cam 42, thereby switching the electric friction clutch device 19 to the connected mode. As a result, the second clutch member 22 (input member 4) and the first clutch member 21 rotate together, and the sun gear 15 and the ring gear 16 rotate together.

[0198] When the electric friction clutch device 19 is switched to the connection mode, the rotation of the drive cam 41 adjusts the circumferential phase of the mode select member 88 relative to the second member 87, thereby switching the rotation transmission state switching device 20 to a free mode in which rotation of the first member 86 relative to the second member 87 is permitted, regardless of the relative rotation direction of the first member 86 and the second member 87. As a result, rotation of the first clutch member 21 relative to the fixed portion 11 is permitted, and rotation of the sun gear 15 is permitted.

[0199] In the reduced speed ratio mode, the rotation direction and rotation speed of the sun gear 15, ring gear 16, and carrier 17 become the same, and the entire planetary gear mechanism 6 rotates as a single unit, in a so-called glued state. Therefore, the rotational torque of the input member 4 is transmitted in the order of input member 4, carrier 17, and output member 5, as shown by the thick line in Figure 2(A), and is taken out from the output member 5.

[0200] <High reduction ratio mode> To switch the two-speed transmission 1 to the high reduction ratio mode, the electric friction clutch device 19 is switched to the disengagement mode, and the rotation transmission state switching device 20 is switched to the lock mode.

[0201] Specifically, the electric friction clutch device 19 is switched to the disengagement mode based on the rotation of the drive cam 41 by the electric actuator 25, which increases the axial distance between the drive cam 41 and the driven cam 42. As a result, the second clutch member (input member 4) and the first clutch member 21 begin to rotate relative to each other, and the sun gear 15 and the ring gear 16 become able to rotate relative to each other.

[0202] As the electric friction clutch device 19 is switched to the disengagement mode, the rotation of the drive cam 41 switches the rotation transmission state switching device 20 to a lock mode in which the rotation of the first member 86 relative to the second member 87 is prevented, regardless of the relative rotation direction of the first member 86 and the second member 87. As a result, the rotation of the first clutch member 21 relative to the fixed portion 11 is prevented, and the rotation of the sun gear 15 is prevented.

[0203] In high reduction ratio mode, the rotational torque of the input member 4 is transmitted in the following order, as shown by the thick line in Figure 2(B): input member 4, ring gear 16, rotational motion of planetary gear 18, revolutionary motion of planetary gear 18 based on meshing with sun gear 15, carrier 17, and output member 5, and is extracted from output member 5. In high reduction ratio mode, the reduction ratio between the input member 4 and output member 5 is determined by the gear ratio between the ring gear 16 and the sun gear 15 (number of teeth of ring gear 16 / number of teeth of sun gear 15).

[0204] In the two-speed transmission 1 of this example, the reduction ratio between the input member 4 and the output member 5 can be switched between high and low by switching the mode of the electric friction clutch device 19 and the mode of the rotational transmission state switching device 20, based on the rotational drive of one drive cam 41 by one electric actuator 25. Specifically, for example, in the region where the power input to the input member 4 is low speed and high torque, the two-speed transmission 1 is switched to the high reduction ratio mode, and in the region where the power is high speed and low torque, it is switched to the low reduction ratio mode. As a result, the acceleration performance and high-speed performance of electric vehicles and hybrid vehicles when running using only an electric motor as the power source can be made to be similar to that of a gasoline engine vehicle shown by the dashed line c in Figure 21, with characteristics such as the portion to the left of point P in the solid line a of Figure 21 and the portion to the right of point P in the dashed line b being continuous.

[0205] In the two-speed transmission 1 of this example, a hydraulic system for controlling friction engagement devices such as clutches and brakes is not required. Therefore, in electric vehicles and hybrid vehicles, the system can be simplified, costs can be reduced, and energy efficiency can be improved.

[0206] <Reduction ratio switching mode> When the 2-speed transmission 1 is switched from the high reduction ratio mode to the reduced speed ratio mode during normal forward driving of the vehicle, first, based on adjusting the circumferential phase of the mode select member 88 with respect to the second member 87, the projection 94 pushes only the second engaging claw 98 radially outward against the elasticity of the second claw biasing member 92, as shown in Figure 16(C). As a result, only the first engaging claw 96 engages with the engaging recess 93 of the first member 86, and the rotation transmission state switching device 20 switches to a one-way clutch mode that allows the first member 86 to rotate only in the predetermined direction (the predetermined direction in Figure 16(C)) relative to the second member 87, and prevents rotation in the opposite direction.

[0207] Simultaneously with, or after, the rotation transmission state switching device 20 switches to one-way clutch mode, the electric friction clutch device 19 starts switching from disconnection mode to connection mode. During the switching of the electric friction clutch device 19 from disconnection mode to connection mode, based on the rotation of the drive cam 41, the rolling elements 83 move down the gently sloping surface portion 60b of the drive cam surface 58, as shown in Figure 10(B) and Figure 10(A). As the amount of the rolling elements 83 ride up from the first bottom portion 60a of the drive cam surface 58 gradually decreases, the force with which the first friction plate 39 and the second friction plate 40 press against each other gradually increases (the fastening force F of the friction engagement portion 23 gradually increases). At this time, the input member 4 rotates while sliding (sliding) the axial sides of the second friction plate 40 against the axial sides of the first friction plate 39.

[0208] As the input member 4 rotates in the forward direction, the fastening force F of the friction engagement portion 23 gradually increases, causing the torque applied to the first member 86 of the rotation transmission state switching device 20 in the direction opposite to the predetermined direction to gradually decrease. At this time, since the rotation transmission state switching device 20 is switched to one-way clutch mode, the first member 86 does not rotate even if torque is applied to the first member 86 in the direction opposite to the predetermined direction. After the torque applied to the first member 86 in the direction opposite to the predetermined direction gradually decreases to zero, when the direction of the torque applied to the first member 86 reverses (torque is applied to the first member 86 in the predetermined direction), rotation of the first member 86 in the predetermined direction is permitted at that moment. Subsequently, the rotation transmission state switching device 20 is switched to free mode, and the two-speed transmission 1 is switched to the reduced speed ratio mode.

[0209] In the two-speed transmission 1 of this example, the gear ratio switching mode is passed through during the transition from the high reduction ratio mode to the low reduction ratio mode while driving forward normally. Therefore, the shift shock associated with the mode switching is suppressed, and torque loss is also suppressed.

[0210] In other words, in this example, the rotation transmission state switching device 20 is set to one-way clutch mode before the electric friction clutch device 19 begins to switch from the disconnection mode to the connection mode in order to switch from the high reduction ratio mode to the reduced speed ratio mode based on the rotation of the drive cam 41. For this reason, in order to switch the electric friction clutch device 19 from the disconnection mode to the connection mode, the fastening force F of the friction engagement part 23 is gradually increased, so that the rotation of the sun gear 15 in the predetermined direction is permitted at the moment the direction of the torque applied to the sun gear 15 is reversed. As a result, torque loss in the two-speed transmission 1 can be suppressed while suppressing the shift shock associated with mode switching.

[0211] In the reduction ratio switching mode, the reduction ratio between the input member 4 and the output member 5 is the same as the reduction ratio in the high reduction ratio mode when the fastening force F of the friction engagement part 23 is small enough that no torque loss occurs at the contact points between the axial sides of the first friction plate 39 and the axial sides of the second friction plate 40. On the other hand, when the fastening force F of the friction engagement part 23 is increased to a size that allows torque to be transmitted without slippage at the contact points between the axial sides of the first friction plate 39 and the axial sides of the second friction plate 40, it is the same as the reduction ratio in the reduced speed ratio mode, i.e., 1.

[0212] When the fastening force F of the friction engagement portion 23 is such that slippage occurs at the contact points between the axial sides of the first friction plate 39 and the axial sides of the second friction plate 40, the reduction ratio between the input member 4 and the output member 5 will be a value corresponding to the magnitude of the input torque, rotational speed, etc.

[0213] When the input member 4 is rotating in the forward direction, and during the switching from the high reduction ratio mode to the reduction ratio switching mode, a torque is applied to the second member 87 of the rotation transmission state switching device 20 in the direction opposite to the predetermined direction. In the rotation transmission state switching device 20, rotation of the second member 87 in the direction opposite to the predetermined direction is prevented even during the switching from the lock mode to the one-way clutch mode. That is, during the switching from the high reduction ratio mode to the reduction ratio switching mode, the reduction ratio between the input member 4 and the output member 5 is the same as the reduction ratio in the high reduction ratio mode.

[0214] When the input member 4 is rotating in the forward direction, and during the switching from the reduction ratio switching mode to the reduced speed ratio mode, torque is applied to the second member 87 of the rotation transmission state switching device 20 in the predetermined direction. In the rotation transmission state switching device 20, rotation of the second member 87 in the predetermined direction is permitted even during the switching from the one-way clutch mode to the free mode.

[0215] Additionally, the two-speed transmission 1 may have a neutral mode in which torque is not transmitted between the input member 4 and the output member 5. To switch the two-speed transmission 1 to neutral mode, the electric friction clutch device 19 is switched to the disengagement mode, and the rotation transmission state switching device 20 is switched to the free mode. In neutral mode, the input member 4 and the output member 5 rotate freely relative to each other, and torque is not transmitted between the input member 4 and the output member 5.

[0216] Additionally or alternatively, the two-speed transmission 1 may have a parking lock mode that locks the rotation of the output member 5. To switch the two-speed transmission 1 to parking lock mode, the electric friction clutch device 19 is switched to connection mode, and the rotation transmission state switching device 20 is switched to lock mode. In parking lock mode, the rotation of the input member 4 and the output member 5 is locked.

[0217] The two-speed transmission of this disclosure can also be applied to structures that have a rotational transmission state switching device that does not have a one-way clutch mode, i.e., has only a free mode and a locked mode. In such an application, when switching from a high reduction ratio mode to a reduced speed ratio mode, the rotational transmission state switching device is switched from the locked mode to the free mode, and then the electric friction clutch device is switched from the disconnected mode to the connected mode.

[0218] [Example 2] A second example of the embodiment of this disclosure will be described with reference to Figure 18.

[0219] In this example, in the cam device 24a, the receiving-side preload cam surface 69a provided on the driven cam 42a is composed of a part of a concave surface 118 that has a V-shape when viewed radially and is formed on the side surface of the driven cam 42a on one axial side (right side in Figure 18). That is, the concave surface 118 has a pair of inclined surfaces 119a and 119b that are inclined in a direction toward one axial side as they move from the center in the circumferential direction (up and down direction in Figure 18) toward both sides in the circumferential direction. The receiving-side preload cam surface 69a is composed of one of the pair of inclined surfaces 119a and 119b (upper side in Figure 18), which is the inclined surface 119a.

[0220] In this example, in the cam device 24a, the pressing preload cam surface 70a provided on the side member 44a is composed of a part of a convex surface 120 that has a V-shape when viewed radially and is formed on the side surface of the side member 44a on the other axial side (left side in Figure 18). That is, the convex surface 120 has a pair of inclined surfaces 121a and 121b that are inclined in a direction toward one side in the axial direction as they move from the center in the circumferential direction toward both sides in the circumferential direction. The pressing preload cam surface 70a is composed of one of the pair of inclined surfaces 121a and 121b (the upper part in Figure 18), namely the inclined surface 121a.

[0221] The other components and effects of the second example are the same as those of the first example.

[0222] [Example 3] A third example of the embodiments of this disclosure will be described with reference to Figure 19.

[0223] In this example, in the cam device 24b, the receiving-side preload cam surface 69b provided on the driven cam 42b and the pushing-side preload cam surface 70b provided on the side member 44b each have a convex curved shape when viewed from the radial direction.

[0224] The other components and effects of the third example are the same as those of the first example.

[0225] [Example 4] A fourth example of the embodiments of this disclosure will be described with reference to Figure 20.

[0226] In this example, in the cam device 24c, an engaging element 122 is sandwiched between a receiving-side preload cam surface 69 provided on the driven cam 42 and a pushing-side preload cam surface 70 provided on the side member 44. The engaging element 122 can be made of balls, rollers, or the like. In this example, the engaging element 122 is made of balls.

[0227] The other components and effects of the fourth example are the same as those of the first example.

[0228] The structure of this disclosure can be implemented by appropriately combining the structures of each embodiment described above, to the extent that no inconsistencies arise. [Explanation of symbols]

[0229] 1. 2-speed transmission 2 Electric motor 3 Differential device 4 Input Members 5 Output component 6 Planetary gear mechanism 7. Power transmission path switching device 8 Output shafts 9 Drive gear 10 Input Gears 11 Fixed part 12 Output Gears 13 Ring gear 14 drive wheels 15 Sangiya 16 Ring Gear 17 Careers 18 Planetary Gear 19 Electric friction clutch device 20 Rotational Transmission State Switching Device 21 First clutch member 22 Second clutch member 23 Friction engagement part 24, 24a, 24b, 24c Cam mechanism 25 Electric Actuators 26 Locking groove 27 Flange section 27a Flange element 28 Circular part 29 Cylindrical section 30 through hole 31 Shaft member 32 1st small diameter cylinder part 33 Large diameter cylindrical section 34 Medium diameter cylinder part 35 Second small diameter cylinder part 36 Protrusion 37 Mating surface part 38 Step surface 39 1st friction plate 40 Second friction plate 41 Drive Cam 42, 42a, 42b Driven cam 43 Support Members 44, 44a, 44b Side members 45. Biasing member 46 Support member side engagement portion 46a Teeth 47 Cylindrical section 48 Outward flange section 49 Radial bearings 50 inner ring 51 Outer ring 52 Rolling element 53 Angular Contact Ball Bearings 54 Inner circle 55 Outer ring 56 balls 57 Driven cam side engagement portion 57a Teeth 58 Drive cam surface 59 Rolling element 60a First bottom 60b Gentle slope section 60c 1st flat surface part 60d slope section 60e 2nd bottom 60f 1st medium slope section 60g 2nd flat surface part 60h 2nd medium slope section 61 Wheel Teeth 62 Pin section 63 Rectangular hole 64a, 64b Support plate part 65a, 65b support hole 66 Support shaft Around 67 68 Side member side engagement portion 68a Teeth 69, 69a, 69b Receiving side preload cam surface 70, 70a, 70b Pressing side preload cam surface 71 Shift motor 72 Reducer 73a, 73b Support bearings 74 Elastic biasing mechanism 75 Retaining ring 76 Retaining ring 77 Pistons 78 Elastic members 79 Thrust bearings 80 Pressing member 81 Preloading member 82a, 82b Raceway ring 83 Rolling element 84 Base 85 Partial cylindrical section 86 First Member 87 Second Member 88 Mode Select Components 89 1st claw member 90 Second claw member 91 First claw biasing member 92 Second claw biasing member 93 Engaging recess 94 Protrusion 95 1st base 96 First Engaging Claw 97 Second base portion 98 Second engaging claw 99 Convex portion 100 Concavo-convex portion 101 Outer diameter side concavo-convex engaging portion 102 Inner diameter side concavo-convex engaging portion 103 Inner diameter side concavo-convex engaging portion 104 Base portion 105 Cylindrical portion 106 First holding recess 107 Second holding recess 108a, 108b Spring holding portions 109a, 109b Pedestal portions 110 Base portion 111 Annular convex portion 112 Plate-side engaging hole 113 Concavo-convex portion 114 Cover body 115 Retaining ring 116 Pressing member 117 Worm 118 Concave surface 119a, 119b Inclined surface portions 120 Convex surface 121a, 121b Inclined surface portions 122 Engaging element

Claims

1. A support member having an engagement portion on the support member side, A drive cam is supported such that it is rotatable relative to the support member, but axially displaceable relative to the support member, A driven cam having a driven cam-side engaging portion, the driven cam-side engaging portion being engaged with the support member-side engaging portion such that it is able to move axially and its rotation is restricted, and the driven cam is positioned on one side of the drive cam in the axial direction, and as the drive cam rotates, it moves axially relative to the support member, thereby expanding and contracting the axial distance between it and the drive cam, A side member having a side member-side engaging portion, the side member-side engaging portion being engaged with the support member-side engaging portion in such a way that it allows axial displacement and restricts rotation, and the side member being positioned on one axial side of the driven cam, A biasing member that elastically biases the side member toward the other axial direction, Equipped with, The drive cam has, as rotational phases, a first phase in which the direction of the circumferential component of the force acting from the drive cam to the driven cam is in a predetermined direction, and a second phase in which the direction of the circumferential component of the force acting from the drive cam to the driven cam is in the opposite direction to the predetermined direction. The side member applies a rotational restricting force to the driven cam having a circumferential component in the predetermined direction, based on the biasing force of the biasing member. The magnitude of the torque based on the circumferential component of the rotational restricting force is greater than the magnitude of the torque based on the circumferential component of the force acting from the drive cam to the driven cam in the second phase. Cam mechanism.

2. The cam device according to claim 1, wherein the engagement portions between the support member-side engagement portion, the driven cam-side engagement portion, and the side member-side engagement portion are configured by spline engagement portions.

3. The cam device according to claim 1, having one of the following configurations for expanding or contracting the axial distance between the drive cam and the driven cam in accordance with the rotation of the drive cam: a configuration in which the drive cam surface provided on the drive cam and the driven cam surface provided on the driven cam slide directly against each other; a configuration in which a plurality of rolling elements are sandwiched between the drive cam surface provided on the drive cam and the driven cam surface provided on the driven cam; and a configuration in which a plurality of rolling elements supported by one of the cams, the drive cam or the driven cam, are in rolling contact with the cam surface provided on the other of the cams, the drive cam or the driven cam.

4. The cam device according to claim 1, wherein the side member has one of the following configurations for applying the rotation restricting force to the driven cam based on the biasing force of the biasing member: a configuration in which a receiving preload cam surface provided on the driven cam and a pushing preload cam surface provided on the side member are in direct contact; a configuration in which an engaging element is sandwiched between a receiving preload cam surface provided on the driven cam and a pushing preload cam surface provided on the side member; and a configuration in which an engaging element supported on one of the driven cam and the side member is in contact with a preload cam surface provided on the other of the driven cam and the side member.

5. Electric friction clutch device, A rotational transmission state switching device is provided, The aforementioned electric friction clutch device, First clutch member and A second clutch member is supported coaxially with the first clutch member and capable of relative rotation with respect to the first clutch member, A friction engagement portion is provided between the first clutch member and the second clutch member, having at least one first friction plate and at least one second friction plate, which are supported to allow relative axial displacement, A cam device comprising a drive cam and a driven cam supported to allow relative rotation and relative axial displacement with respect to the drive cam, wherein the axial distance between the drive cam and the driven cam expands and contracts as the drive cam rotates, The system includes an electric actuator that rotates the drive cam, and The device is configured to be switchable between a connection mode, in which torque is transmitted between the first clutch member and the second clutch member by expanding or contracting the axial distance between the drive cam and the driven cam, thereby pressing the at least one first friction plate and the at least one second friction plate against each other, and a disconnection mode, in which torque is not transmitted between the first clutch member and the second clutch member by releasing the force pressing the at least one first friction plate and the at least one second friction plate against each other. The rotation transmission state switching device is A first member and a second member arranged coaxially with respect to each other, The system includes a mode select member that rotates or is displaced axially in conjunction with the rotation of the drive cam, Based on the rotation or axial displacement of the mode select member, the system is configured to switch between a locked mode, in which the rotation of the first member relative to the second member is prevented regardless of the relative rotation direction between the first and second members, and a free mode, in which the rotation of the first member relative to the second member is permitted regardless of the relative rotation direction between the first and second members. The cam device is configured according to any one of claims 1 to 4. Power transmission path switching device.

6. Input component and An output member supported to enable relative rotation with respect to the input member, A planetary gear mechanism is disposed between the input member and the output member, The system includes a power transmission path switching device for switching the power transmission path between the input member and the output member, The power transmission path switching device is configured as the power transmission path switching device described in claim 5. The planetary gear mechanism comprises a sun gear, a ring gear arranged coaxially with the sun gear around the sun gear, a carrier supported to allow relative rotation between the sun gear and the ring gear, and a plurality of planetary gears that mesh with the sun gear and the ring gear and are supported on the carrier to allow rotation about their own central axis. The input element, which is one of the sun gear, the ring gear, and the carrier, rotates integrally with the input member, or is composed of the input member itself. An output element, which is one of the sun gear, the ring gear, and the carrier and is a separate element from the input element, rotates integrally with the output member, or is composed of the output member itself. The rotating elements of the sun gear, ring gear, and carrier, excluding the input and output elements, rotate integrally with the first clutch member, or are composed of the first clutch member itself. Two-speed transmission.

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