Clutch device

Abstract

A pressure plate 70 has a pressure-side assist cam surface 90A and a pressure-side slipper cam surface 90S. The area of the pressure-side assist cam surface 90A is larger than the area of the pressure-side slipper cam surface 90S. A clutch center 40 has a center-side assist cam surface 60A and a center-side slipper cam surface 60S. The area of the center-side assist cam surface 60A is larger than the area of the center-side slipper cam surface 60S.

Description

Clutch device

[0001] The present invention relates to a clutch device. More specifically, it relates to a clutch device that arbitrarily transmits or blocks the rotational driving force of an input shaft that is rotationally driven by a power source such as an engine to an output shaft.

[0002] Conventionally, vehicles such as motorcycles have a clutch device. The clutch device is arranged between the engine and the drive wheel, and transmits or blocks the rotational driving force of the engine to the drive wheel. The clutch device usually includes a plurality of input-side rotating plates that rotate by the rotational driving force of the engine, and a plurality of output-side rotating plates connected to an output shaft that transmits the rotational driving force to the drive wheel. The input-side rotating plates and the output-side rotating plates are alternately arranged in the stacking direction, and the transmission or blocking of the rotational driving force is performed by pressing and separating the input-side rotating plates and the output-side rotating plates.

[0003] For example, Patent Document 1 discloses a clutch device including a clutch center and a pressure plate that can approach and separate from the clutch center. The pressure plate is configured to be able to press the input-side rotating plate and the output-side rotating plate. The clutch center and the pressure plate of the clutch device in Patent Document 1 generate a force in a direction to approach the pressure plate to the clutch center when the rotational driving force of the engine can be transmitted to the output shaft, increasing the pressing force between the input-side rotating plate and the output-side rotating plate; and generate a force in a direction to separate the pressure plate from the clutch center when the rotational speed of the clutch center exceeds the rotational speed of the pressure plate, reducing the pressing force between the input-side rotating plate and the output-side rotating plate.

[0004] Japanese Patent No. 6894792

[0005] In the clutch device as described above, when the rotational driving force applied to the clutch device increases, the force applied per unit area of the cam surface increases. To suppress the increase in the force applied per unit area of the cam surface, it is necessary to increase the area of the cam surface. At this time, since the pressure plate and / or the clutch center become larger, the clutch device becomes larger.

[0006] The present invention has been made in view of the above, and its purpose is to provide a clutch device that is compact while suppressing an increase in the force applied per unit area of ​​the cam surface.

[0007] The clutch device according to the present invention is a clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, and comprises a clutch center housed in a clutch housing that rotates upon receiving the rotational driving force and holds a plurality of input-side rotating plates arranged in an axial direction which is the direction of the axis of the output shaft, and rotates together with the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the axial direction; and a pressure plate provided so as to be able to approach and move away from the clutch center in the axial direction and to be rotatable relative to the clutch center, and holding one or more of the plurality of output-side rotating plates and pressing the input-side rotating plates and the output-side rotating plates. The clutch center either does not hold the plurality of output-side rotating plates or holds one or more of the plurality of output-side rotating plates. The pressure plate has a plurality of pressure-side cam portions having a pressure-side assist cam surface and a pressure-side slipper cam surface, and holds more output-side rotating plates than the number of output-side rotating plates held by the clutch center. The pressure-side assist cam surface is configured to increase the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force that moves the pressure plate closer to the clutch center when the pressure plate rotates relative to the clutch center. The pressure-side slipper cam surface is configured to decrease the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force that moves the pressure plate away from the clutch center when the pressure plate rotates relative to the clutch center. The area of ​​the pressure-side assist cam surface is larger than the area of ​​the pressure-side slipper cam surface.

[0008] In the clutch device according to the present invention, the area of ​​the pressure-side assist cam surface is larger than the area of ​​the pressure-side slipper cam surface. Here, if the pressure plate holds more output-side rotating plates than the clutch center holds, a large portion of the rotational driving force of the input shaft is applied to the pressure-side assist cam surface. In other words, a large torque is applied to the pressure-side assist cam surface. For this reason, it is desirable to increase the area of ​​the pressure-side assist cam surface so that the surface pressure it receives is appropriate. However, if the area of ​​the pressure-side slipper cam surface is made equal to the area of ​​the pressure-side assist cam surface, the pressure-side slipper cam surface will become unnecessarily large, which may lead to an increase in the size of the clutch device. However, according to the present invention, since the area of ​​the pressure-side assist cam surface is larger than the area of ​​the pressure-side slipper cam surface, even when the pressure plate holds more output-side rotating plates than the clutch center holds, the clutch device can be made compact while ensuring that the surface pressure received by the pressure-side assist cam surface is appropriate.

[0009] Another clutch device according to the present invention is a clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that rotates upon receiving the rotational driving force and holds a plurality of input-side rotating plates arranged in an axial direction which is the direction of the axis of the output shaft, and which rotates together with the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the axial direction; and a pressure plate provided so as to be able to approach and move away from the clutch center in the axial direction and to be rotatable relative to the clutch center, and which holds one or more of the plurality of output-side rotating plates and presses the input-side rotating plates and the output-side rotating plates. The clutch center either does not hold the plurality of output-side rotating plates or holds one or more of the plurality of output-side rotating plates. The pressure plate holds more output-side rotating plates than the number of output-side rotating plates held by the clutch center. The clutch center has a plurality of center-side cam portions having a center-side assist cam surface and a center-side slipper cam surface. The center-side assist cam surface is configured to increase the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force that moves the pressure plate closer to the clutch center when the clutch center rotates relative to the pressure plate. The center-side slipper cam surface is configured to decrease the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force that moves the pressure plate away from the clutch center when the clutch center rotates relative to the pressure plate. The area of ​​the center-side assist cam surface is larger than the area of ​​the center-side slipper cam surface.

[0010] In other clutch devices according to the present invention, the area of ​​the center-side assist cam surface is larger than the area of ​​the center-side slipper cam surface. Here, when the pressure plate holds more output-side rotating plates than the clutch center holds, a large portion of the rotational driving force of the input shaft is applied to the center-side assist cam surface. That is, a large torque is applied to the center-side assist cam surface. For this reason, it is desirable to increase the area of ​​the center-side assist cam surface so that the surface pressure received by the center-side assist cam surface is appropriate. However, if the area of ​​the center-side slipper cam surface is also equal to the area of ​​the center-side assist cam surface, the center-side slipper cam surface will become unnecessarily large, which may lead to an increase in the size of the clutch device. However, according to the present invention, since the area of ​​the center-side assist cam surface is larger than the area of ​​the center-side slipper cam surface, even when the pressure plate holds more output-side rotating plates than the clutch center holds, the clutch device can be compact while ensuring that the surface pressure received by the center-side assist cam surface is appropriate.

[0011] According to the present invention, it is possible to provide a clutch device that is compact while suppressing the increase in the force applied per unit area of ​​the assist cam surface.

[0012] Figure 1 is a cross-sectional view of the clutch device according to the first embodiment. Figure 2 is an enlarged view of the area near the output side rotating plate as seen from the first direction. Figure 3 is a perspective view of the clutch center according to the first embodiment. Figure 4 is a plan view of the clutch center according to the first embodiment as seen from the second direction. Figure 5 is a plan view of the clutch center according to the first embodiment as seen from the first direction. Figure 6 is a side view of the clutch center according to the first embodiment. Figure 7 is a perspective view of the pressure plate according to the first embodiment. Figure 8 is a perspective view of the pressure plate according to the first embodiment. Figure 9 is an enlarged view of the area around the protruding part in Figure 1. Figure 10 is a plan view of the pressure plate according to the first embodiment as seen from the first direction. Figure 11 is a side view of the pressure plate according to the first embodiment. Figure 12 is a cross-sectional view of the pressure plate according to the first embodiment. Figure 13A is a schematic diagram illustrating the operation of the center side assist cam surface and the pressure side assist cam surface. Figure 13B is a schematic diagram illustrating the operation of the center-side slipper cam surface and the pressure-side slipper cam surface. Figure 14 is a plan view of the pressure plate according to the first embodiment, viewed from the second direction. Figure 15A is a plan view of the first spring and the second spring. Figure 15B is a side view of the first spring and the second spring. Figure 16 is a plan view showing the clutch center and the pressure plate assembled. Figure 17 is a cross-sectional view of the clutch device when the center-side slipper cam surface and the pressure-side slipper cam surface are in contact. Figure 18 is a cross-sectional view of the clutch device in a half-clutch state. Figure 19 is a cross-sectional view of the clutch device when the pressure plate is in contact with the stopper plate. Figure 20A is a cross-sectional view of the area around the protrusion before the pressure plate is assembled to the clutch center. Figure 20B is a cross-sectional view of the area around the protrusion when the pressure plate is assembled to the clutch center. Figure 20C is a view of Figure 20A from the first direction. Figure 21 is a cross-sectional view of the clutch device according to the first modified example. Figure 22 is a perspective view of the pressure plate according to the second modified example. Figure 23 is a perspective view of the pressure plate according to the second modified example. Figure 24 is a cross-sectional view of the pressure plate according to the second modified example.Figure 25 is a perspective view of the clutch center according to the second embodiment. Figure 26 is a perspective view of the clutch center according to the second embodiment. Figure 27 is a perspective view of the pressure plate according to the second embodiment. Figure 28 is a plan view of the pressure plate according to the second embodiment. Figure 29 is a cross-sectional view of the clutch device according to the third embodiment. Figure 30 is an enlarged view of the area around the protruding portion in Figure 29.

[0013] Hereinafter, embodiments of the clutch device according to the present invention will be described with reference to the drawings. Naturally, the embodiments described herein are not intended to particularly limit the present invention. Furthermore, the same reference numerals are used for members and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate.

[0014] <First Embodiment> Figure 1 is a cross-sectional view of the clutch device 10 according to this embodiment. The clutch device 10 is installed in a vehicle such as a motorcycle. The clutch device 10 is a device that transmits or interrupts the rotational driving force of the input shaft (e.g., crankshaft) of a power source to the output shaft 15. The power source is, for example, the engine or electric motor of a motorcycle. The clutch device 10 is a device for transmitting or interrupting the rotational driving force of the input shaft to the drive wheel (rear wheel) via the output shaft 15.

[0015] In the following description, the direction in which the pressure plate 70 and the clutch center 40 of the clutch device 10 are aligned is referred to as direction D. In this embodiment, direction D is approximately horizontal. The direction in which the pressure plate 70 approaches the clutch center 40 is referred to as the first direction D1, and the direction in which the pressure plate 70 moves away from the clutch center 40 is referred to as the second direction D2. In this embodiment, the axial direction of the output shaft 15, the axial direction of the clutch housing 30, the axial direction of the clutch center 40, and the axial direction of the pressure plate 70 are the same as direction D. In the following description, unless otherwise specified, "axial direction" refers to the axial direction of the output shaft 15. Furthermore, the circumferential directions of the output shaft 15, the clutch housing 30, the clutch center 40, and the pressure plate 70 are the same, and this is referred to as the circumferential direction S (see Figure 2). With respect to the circumferential direction S, the direction from one pressure-side cam portion 90 to the other pressure-side cam portion 90 is defined as the first circumferential direction S1 (see Figure 7), and the direction from the other pressure-side cam portion 90 to the first pressure-side cam portion 90 is defined as the second circumferential direction S2 (see Figure 7). The pressure plate 70 and the clutch center 40 rotate in the first circumferential direction S1. In this embodiment, the radial directions of the output shaft 15, clutch housing 30, clutch center 40, and pressure plate 70 are the same. In the following description, unless otherwise specified, "radial direction" refers to the radial direction of the output shaft 15. However, the above directions are merely defined for the convenience of explanation and do not limit the installation configuration of the clutch device 10 in any way, nor do they limit the present invention in any way.

[0016] Figure 1 shows the clutch device 10 in the clutch ON state, as described later, with the pressure plate 70 closest to the clutch center 40, and the input side rotating plate 20 and the output side rotating plate 22 pressed against each other. As shown in Figure 1, the clutch device 10 includes an output shaft 15, an input side rotating plate 20, an output side rotating plate 22, a clutch housing 30, a clutch center 40, a pressure plate 70, a clutch spring 25, a stopper plate 100, a judder spring 120, a first spring 130A, and a second spring 130B.

[0017] As shown in Figure 1, the output shaft 15 is a hollow shaft. One end of the output shaft 15 rotatably supports the input gear 35 and clutch housing 30, which will be described later, via a needle bearing 15A. The output shaft 15 is fixed to the clutch center 40 by a nut 15B. The output shaft 15 rotates integrally with the clutch center 40. The other end of the output shaft 15 is connected to, for example, a motorcycle transmission (not shown).

[0018] As shown in Figure 1, the output shaft 15 is equipped with a push rod 16A in its hollow portion 15H and a push member 16B provided adjacent to the push rod 16A. The hollow portion 15H functions as an oil flow passage. The oil flows inside the output shaft 15, i.e., inside the hollow portion 15H. The push rod 16A and the push member 16B are slidably mounted inside the hollow portion 15H of the output shaft 15. One end of the push rod 16A (the left end in the figure) is connected to a motorcycle clutch operating lever (not shown), and when the clutch is disengaged, the operation of the clutch operating lever causes it to slide inside the hollow portion 15H and press the push member 16B in a second direction D2. A part of the push member 16B protrudes outward from the output shaft 15 (in this case, in the second direction D2) and is connected to a release bearing 18 provided on the pressure plate 70. The push rod 16A and other parts of the push member 16B are formed to be thinner than the inner diameter of the hollow portion 15H, ensuring oil flow within the hollow portion 15H. The push rod 16A may, for example, be connected to a clutch operation switch, and pressing the clutch operation switch will cause the push member 16B to be pressed in the second direction D2.

[0019] The clutch housing 30 is made of an aluminum alloy. The clutch housing 30 is formed in a bottomed cylindrical shape. As shown in Figure 1, the clutch housing 30 has a substantially circular bottom wall 31 and a side wall 33 extending in a second direction D2 from the edge of the bottom wall 31. The clutch housing 30 holds a plurality of input-side rotating plates 20.

[0020] As shown in Figure 1, an input gear 35 is provided on the bottom wall 31 of the clutch housing 30. The input gear 35 is fixed to the bottom wall 31 by rivets 35B via a torque damper 35A. The input gear 35 meshes with a drive gear (not shown) that rotates due to the rotational drive of the engine's input shaft. The input gear 35 rotates independently of the output shaft 15 and integrally with the clutch housing 30.

[0021] The input-side rotating plate 20 is rotationally driven by the rotational drive of the input shaft. As shown in Figure 1, the input-side rotating plate 20 is held on the inner circumferential surface 33N of the side wall 33 of the clutch housing 30. In this embodiment, the inner circumferential surface 33N extends radially outward as it moves toward the second direction D2, and is inclined from the axial direction of the output shaft 15. The input-side rotating plate 20 is held by engaging with a notch 30C (see also Figure 2) formed in the side wall 33 of the clutch housing 30. The input-side rotating plate 20 is held in the clutch housing 30 by spline fitting. The input-side rotating plate 20 is provided so as to be displaceable along the axial direction of the clutch housing 30. The input-side rotating plate 20 is provided so as to be rotatable integrally with the clutch housing 30.

[0022] The input-side rotating plate 20 is a component that is pressed against the output-side rotating plate 22. The input-side rotating plate 20 is a flat plate formed in an annular shape. The input-side rotating plate 20 is formed by punching out an annular shape from a thin sheet of SPCC (cold-rolled steel sheet) material. Friction material (not shown) consisting of multiple pieces of paper is attached to the front and back surfaces of the input-side rotating plate 20. Grooves with a depth of several micrometers to tens of micrometers are formed between the friction material to hold oil.

[0023] All output-side rotating plates 22 are held by the pressure plate 70. The output-side rotating plates 22 are held by the pressure-side fitting teeth 77 of the pressure plate 70, which will be described later. The output-side rotating plates 22 are provided so as to be displaceable along the axial direction of the clutch center 40. The output-side rotating plates 22 are provided so as to be rotatable integrally with the clutch center 40.

[0024] The output-side rotating plate 22 is a component that is pressed against the input-side rotating plate 20. The output-side rotating plate 22 is a flat plate formed in an annular shape. The output-side rotating plate 22 is formed by punching out an annular shape from a thin sheet material made of SPCC material. Grooves with a depth of several micrometers to several tens of micrometers are formed on the front and back surfaces of the output-side rotating plate 22 to retain oil. The front and back surfaces of the output-side rotating plate 22 are each subjected to a surface hardening treatment to improve wear resistance. The friction material provided on the input-side rotating plate 20 may be provided on the output-side rotating plate 22 instead of the input-side rotating plate 20, or it may be provided on both the input-side rotating plate 20 and the output-side rotating plate 22.

[0025] Figure 2 shows the clutch housing 30, the input-side rotating plate 20, the output-side rotating plate 22, and the protruding portion 75 of the pressure plate 70, which will be described later. The inner circumferential surface 33N of the side wall 33 (see Figure 1) faces radially outward from the protruding portion 75. As shown in Figure 2, the output-side rotating plate 22 has a ring-shaped body portion 22a, a plurality of rotating plate fitting teeth 22b, and a plurality of rotating plate grooves 22c. The rotating plate fitting teeth 22b extend radially inward from the inner circumferential edge 22N of the body portion 22a. Multiple rotating plate fitting teeth 22b are formed in a row in the circumferential direction S. The rotating plate grooves 22c are grooves formed between adjacent rotating plate fitting teeth 22b in the circumferential direction S. The pressure-side fitting teeth 77, which will be described later, fit into the rotating plate grooves 22c. When the rotational axes of the clutch housing 30 and the output-side rotating plate 22 are located coaxially, the radial distance between the inner circumferential surface 33N of the side wall 33 and the outer circumferential edge 22U of the output-side rotating plate 22 is length L20. As shown in Figure 1, length L20 is the narrowest radial distance between the inner circumferential surface 33N and the output-side rotating plate 22 in direction D, that is, the distance closest to the first direction D1.

[0026] The clutch center 40 is housed in the clutch housing 30. The clutch center 40 is positioned concentrically with the clutch housing 30. As shown in Figure 3, the clutch center 40 has a ring-shaped center-side flange 68, a center-side body portion 42 located radially inward of the center-side flange 68, and a center-side recess 59 formed between the center-side body portion 42 and the center-side flange 68. The clutch center 40 is rotationally driven together with the output shaft 15 (see Figure 1).

[0027] As shown in Figure 3, the center-side main body portion 42 comprises an annular boss portion 43, a plurality of center-side cam portions 60 connected to the boss portion 43, and a plurality of center-side fitting portions 58. The radially inner portion of the boss portion 43 constitutes an output shaft holding portion 50 that is held by the output shaft 15. As shown in Figure 4, the radially outer edge portion 43E of the boss portion 43 is connected to the center-side cam portion 60. In this embodiment, a center-side cam portion 60 is connected to each of the three outer edge portions 43E.

[0028] As shown in Figure 3, the output shaft holder 50 has an insertion hole 51 into which the output shaft 15 (see Figure 1) is inserted and spline fitted. Multiple spline grooves are formed on the inner circumferential surface 50A of the output shaft holder 50 along the axial direction. The output shaft 15 is connected to the output shaft holder 50.

[0029] As will be described in detail later, the clutch device 10 is equipped with an assist & slipper (registered trademark) mechanism. The assist & slipper (registered trademark) mechanism is a mechanism that generates assist torque, which is a force that increases the pressing force (contact force) between the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 1), or slipper torque, which is a force that decreases the pressing force between the input side rotating plate 20 and the output side rotating plate 22. The center side cam portion 60 has cam surfaces 60A and 60S, which are inclined surfaces that constitute the assist & slipper (registered trademark) mechanism. The center side cam portion 60 is connected to the radially outside of the boss portion 43. The center side cam portion 60 protrudes from the boss portion 43 in a second direction D2. As shown in Figure 4, the center side cam portions 60 are arranged at equal intervals in the circumferential direction S of the clutch center 40. In this embodiment, the clutch center 40 has three center side cam portions 60, but the number of center side cam portions 60 is not limited to three.

[0030] As shown in Figure 3, the end 60E of the center cam portion 60 on the first direction D1 side is connected to the center fitting portion 58. As shown in Figure 4, the center cam portion 60 is formed integrally, but here it is assumed to have the following two parts aligned in the circumferential direction S. The center cam portion 60 comprises an assist cam portion 63A having a center assist cam surface 60A, and a slipper cam portion 63S having a center slipper cam surface 60S. The slipper cam portion 63S is aligned with respect to the assist cam portion 63A on the first circumferential direction S1 side. The assist cam portion 63A and the slipper cam portion 63S are formed integrally. As shown in Figure 3, the assist cam portion 63A extends further toward the second direction D2 than the slipper cam portion 63S. The dimension of the assist cam portion 63A in direction D is greater than the dimension of the slipper cam portion 63S in direction D. The assist-side cam portion 63A and the slipper-side cam portion 63S may be formed as separate components.

[0031] In this embodiment, the clutch center 40 rotates in the direction from the assist-side cam portion 63A toward the slipper-side cam portion 63S (i.e., the first circumferential direction S1). The center-side assist cam surface 60A is configured to generate a force in the direction from the pressure plate 70 toward the clutch center 40 in order to increase the pressing force (contact force) between the input-side rotating plate 20 (see Figure 1) and the output-side rotating plate 22 (see Figure 1) when the clutch center 40 rotates relative to the pressure plate 70 (see Figure 1). In this embodiment, when the above force is generated, the position of the pressure plate 70 relative to the clutch center 40 does not change, and the pressure plate 70 does not need to physically approach the clutch center 40. However, the pressure plate 70 may be physically displaced relative to the clutch center 40. The center-side assist cam surface 60A extends toward the second circumferential direction S2 as it goes toward the second direction D2, and is inclined with respect to the axial direction. The center-side slipper cam surface 60S is configured to reduce the pressing force (contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the clutch center 40 rotates relative to the pressure plate 70. When the pressing force decreases, the position of the pressure plate 70 changes in the circumferential direction S and the axial direction (direction D) so that it moves away from the clutch center 40. The center-side slipper cam surface 60S extends toward the second circumferential direction S2 as it moves toward the second direction D2, and is inclined with respect to the axial direction. As shown in Figure 4, the center-side assist cam surface 60A of one center-side cam portion 60L and the center-side slipper cam surface 60S of the other center-side cam portion 60M face each other in the circumferential direction S. Note that the cross-sectional view in Figure 1 is a cross-sectional view when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, which will be described later, are in contact.

[0032] As shown in Figure 3, a stepped portion 60T is formed next to the center slipper cam surface 60S on the center cam portion 60. The stepped portion 60T extends radially. As shown in Figure 4, the radially inner portion of the stepped portion 60T is connected to the boss portion 43. The radially outer portion of the stepped portion 60T is connected to the center fitting portion 58. The stepped portion 60T is also connected to the end of the center slipper cam surface 60S on the second direction D2 side. Furthermore, the stepped portion 60T is located approximately in the center of the center cam portion 60 in direction D.

[0033] A portion of the end face 63E on the second direction D2 side of the assist-side cam portion 63A and a portion of the end face 63F (see Figure 5) on the first direction D1 side of the assist-side cam portion 63A are positioned offset from each other in the circumferential direction S. As shown in Figure 6, the end of the end face 63E on the first circumferential direction S1 side is offset towards the second circumferential direction S2 side than the end of the end face 63F on the first circumferential direction S1 side.

[0034] As shown in Figure 3, the main outer surface 63P is formed by the outer surface of the assist-side cam portion 63A and the outer surface of the slipper-side cam portion 63S. The main outer surface 63P is formed across the assist-side cam portion 63A and the slipper-side cam portion 63S. In addition, the assist-side cam portion 63A has a sub-outer surface 61A that intersects with the main outer surface 63P. The sub-outer surface 61A is connected to the center-side assist cam surface 60A. The sub-outer surface 61A extends radially inward as it moves toward the first direction D1 and is inclined with respect to the axial direction. That is, the sub-outer surface 61A is inclined to move radially inward from the main outer surface 63P as it moves toward the first direction D1. The sub-outer surface 61A may be parallel to the axis of the output shaft 15. Of the main outer peripheral surface 63P, at least the side on the sub outer peripheral surface 61A (i.e., the side on the second circumferential direction S2) is inclined so that it moves radially outward from the sub outer peripheral surface 61A as it moves toward the first direction D1. Therefore, the radial length of the center-side assist cam surface 60A increases toward the second direction D2. Here, as shown in Figure 4, the longest radial length of the center-side assist cam surface 60A is defined as length L1. The longest radial length of the center-side slipper cam surface 60S is defined as length L2. Length L1 is longer than length L2. The radial midpoint position at the end of the second direction D2 of the center-side assist cam surface 60A coincides with the radial midpoint position at the end of the second direction D2 of the center-side slipper cam surface 60S. Arc AR1, centered on axis CL and passing through the midpoint of the radial direction at the end of the second direction D2 of the center-side assist cam surface 60A, also passes through the midpoint of the radial direction at the end of the second direction D2 of the center-side slipper cam surface 60S. Lengths L1 and L2 may be the same. Arc AR1 is located on the outer diameter side of Arc AR2, which is centered on axis CL and passes through the center 54C of the screw portion 54a, which will be described later. As a result, the center-side assist cam surface 60A and the center-side slipper cam surface 60S are located on the radially outer side of the clutch center 40.Therefore, when torque is transmitted by the center-side assist cam surface 60A or the center-side slipper cam surface 60S, the surface pressure applied to the center-side assist cam surface 60A or the center-side slipper cam surface 60S can be reduced.

[0035] If length L1 is made longer than length L2, the position of the inner diameter end of the center-side assist cam surface 60A at the end of the second direction D2 and the position of the inner diameter end of the center-side slipper cam surface 60S at the end of the second direction D2 may be the same in the radial direction. In this case, the arc AR1, which is centered on axis CL and passes through the midpoint of the radial direction at the end of the center-side assist cam surface 60A in the second direction D2, and the arc, which is centered on axis CL and passes through the midpoint of the radial direction at the end of the center-side slipper cam surface 60S in the second direction D2, will be offset in the radial direction. That is, the arc AR1, which is centered on axis CL and passes through the midpoint of the radial direction at the end of the center-side assist cam surface 60A in the second direction D2, is located on the outer diameter side of the arc, which is centered on axis CL and passes through the midpoint of the radial direction at the end of the center-side slipper cam surface 60S in the second direction D2. The radial length of the center-side assist cam surface 60A at the end in the second direction may be the same as the radial length of the center-side slipper cam surface 60S at the end in the second direction. In this case, when viewed in the direction of the axis CL, the arc AR1 centered on the axis CL and passing through the midpoint of the radial direction at the end of the second direction D2 of the center-side assist cam surface 60A may also pass through the midpoint of the radial direction at the end of the second direction D2 of the center-side slipper cam surface 60S. The main outer peripheral surface 63P (see Figure 3) may be inclined radially inward toward the second direction D2 over its entire length.

[0036] The assist-side cam portion 63A extends further toward the second direction D2 than the slipper-side cam portion 63S. Therefore, as shown in Figure 6, the end 67A of the center-side assist cam surface 60A toward the second direction D2 is located further toward the second direction D2 than the end 67S of the center-side slipper cam surface 60S toward the second direction D2. Also, in direction D, the length L3 of the center-side assist cam surface 60A and the length L4 of the center-side slipper cam surface 60S in direction D are different. Here, length L3 is longer than length L4. Furthermore, as described above, the radial length L1 of the center-side assist cam surface 60A (see Figure 4) is longer than the radial length L2 of the center-side slipper cam surface 60S (see Figure 4). Moreover, as shown in Figure 6, the inclined surface length L5 of the center-side assist cam surface 60A is longer than the inclined surface length L6 of the center-side slipper cam surface 60S. Therefore, the area of ​​the center assist cam surface 60A and the area of ​​the center slipper cam surface 60S are different from each other. Here, the area of ​​the center assist cam surface 60A is larger than that of the center slipper cam surface 60S. However, it is not necessary for all three conditions L1 > L2, L3 > L4, and L5 > L6 to be met; it is acceptable for only one or two of these conditions to be met. Even in such a case, the area of ​​the center assist cam surface 60A can be made larger than the area of ​​the center slipper cam surface 60S. The area of ​​the center assist cam surface 60A is 1.5 to 3 times the area of ​​the center slipper cam surface 60S. Preferably, the area of ​​the center assist cam surface 60A is 1.5 to 2.5 times the area of ​​the center slipper cam surface 60S. In this embodiment, the end 67B of the center assist cam surface 60A on the first direction D1 side and the end 67T of the center slipper cam surface 60S on the first direction D1 side are located in approximately the same position in direction D. However, in order to make the area of ​​the center assist cam surface 60A larger than that of the center slipper cam surface 60S, the end 67B of the center assist cam surface 60A on the first direction D1 side may be positioned on the first direction D1 side of the center slipper cam surface 60S on the first direction D1 side than the end 67T of the center slipper cam surface 60S on the first direction D1 side.

[0037] As shown in Figure 3, the main inner surface 63N is formed by the inner surface of the assist-side cam portion 63A and the inner surface of the slipper-side cam portion 63S. The main inner surface 63N is formed across the assist-side cam portion 63A and the slipper-side cam portion 63S. The inner portions of the assist-side cam portion 63A and the slipper-side cam portion 63S are connected to the boss portion 43 and integrated with the boss portion 43. Therefore, at least a part of the assist-side cam portion 63A and at least a part of the slipper-side cam portion 63S are integrated with the boss portion 43. More specifically, the portions of the assist-side cam portion 63A and the slipper-side cam portion 63S on the first direction D1 side are connected to the boss portion 43.

[0038] As shown in Figure 4, an inner circumferential recess 63R is formed between the center cam portion 60 and the boss portion 43. The inner circumferential recess 63R is recessed in the direction toward the second circumferential direction S2, that is, from the center slipper cam surface 60S toward the center assist cam surface 60A. The end of the inner circumferential recess 63R toward the second circumferential direction S2 is located toward the first circumferential direction S1 than the assist cam portion 63A. The inner circumferential surface of the slipper cam portion 63S is radially separated from the boss portion 43.

[0039] As shown in Figure 3, the assist-side cam portion 63A has an assist-side recess 65 that is recessed in the first direction D1. The assist-side recess 65 is an example of the first recess in the present invention. As shown in Figure 4, the assist-side recess 65 is formed in a substantially rectangular shape when viewed from direction D (i.e., in the axial direction of the output shaft 15). The assist-side recess 65 has a shape that tapers towards the first direction D1. The opening area of ​​the cross section (hereinafter referred to as the cross section) of the assist-side recess 65 perpendicular to direction D becomes smaller towards the first direction D1. As shown in Figure 6, the bottom surface 65E of the assist-side recess 65 is located on the first direction D1 side of the slipper-side cam portion 63S end surface 63G on the second direction side.

[0040] As shown in Figure 5, the slipper-side cam portion 63S has a slipper-side recess 66 that is recessed in the second direction D2. The slipper-side recess 66 is an example of the second recess in the present invention. The slipper-side recess 66 is formed in a substantially rectangular shape when viewed from direction D. The slipper-side recess 66 has a shape that tapers towards the second direction D2. The opening area of ​​the cross-section of the slipper-side recess 66 becomes smaller towards the second direction D2. As shown in Figure 6, the bottom surface 65E of the assist-side recess 65 is located on the first direction D1 side than the bottom surface 66E of the slipper-side recess 66.

[0041] As shown in Figure 3, the clutch center 40 is provided with a plurality (three in this embodiment) of boss portions 54 for supporting the stopper plate 100 (see Figure 1). The plurality of boss portions 54 are arranged at equal intervals in the circumferential direction S. The boss portions 54 are formed in a cylindrical shape. The boss portions 54 are located radially outward from the output shaft holding portion 50. The boss portions 54 extend toward the pressure plate 70 (see Figure 1) (i.e., toward the second direction D2). The boss portions 54 extend toward the second direction D2 than the assist-side cam portion 63A. Part of the boss portion 54 is provided on the assist-side cam portion 63A, and the other part of the boss portion 54 is provided on the slipper-side cam portion 63S. The boss portion 54 is provided across the assist-side cam portion 63A and the slipper-side cam portion 63S. The boss portion 54 penetrates the clutch center 40 in the axial direction (i.e., direction D). As shown in Figure 5, a portion of the boss portion 54 is provided on the end face 63F of the assist-side cam portion 63A.

[0042] As shown in Figure 3, the center-side fitting portion 58 is located radially outward from the output shaft holding portion 50 and the center-side cam portion 60. The center-side fitting portion 58 is located on the first direction D1 side of the center-side cam portion 60. The center-side fitting portion 58 is connected to the center-side cam portion 60 at its second direction D2 end 58D. The first direction D1 end 58E of the center-side fitting portion 58 is located on the first direction D1 side of the center-side pressing surface 69 of the center-side flange 68, which will be described later. The center-side fitting portion 58 is configured to slidably fit into the pressure-side fitting portion 88 (see Figure 7), which will be described later. The outer diameter of the center-side fitting portion 58 is formed with a fitting tolerance that allows oil flowing out from the tip portion 15T (see Figure 1) of the output shaft 15 (see Figure 1) to flow relative to the pressure-side fitting portion 88. That is, a gap is formed between the center-side fitting portion 58 and the pressure-side fitting portion 88, which will be described later. In this embodiment, for example, the center-side fitting portion 58 is formed with an inner diameter that is, for example, 0.1 mm larger than the outer diameter of the pressure-side fitting portion 88.

[0043] As shown in Figures 3 and 4, the clutch center 40 has a center-side cam hole 43H that penetrates a portion of the center-side main body portion 42. The center-side cam hole 43H extends from the side of the boss portion 43 to the radially outer side of the center-side fitting portion 58. Each center-side cam hole 43H is formed between adjacent center-side cam portions 60 in the circumferential direction. As shown in Figure 5, as viewed from direction D, a portion of the center-side assist cam surface 60A is located inside the center-side cam hole 43H. As viewed from direction D, the center-side cam hole 43H has a substantially fan-shaped form. As shown in Figure 4, the boss portion 43 forms an inner edge portion 43Ha that partitions the radially inner side of the center-side cam hole 43H. The radially inner position of the center-side cam hole 43H is located radially inward from the center-side cam portion 60.

[0044] As shown in FIG. 3, the center-side recess 59 is formed on the outer side in the radial direction of the center-side fitting portion 58. The center-side recess 59 is connected to the center-side fitting portion 58 and the center-side flange 68. The center-side recess 59 is formed between the center-side fitting portion 58 and the center-side pressing surface 69 of the center-side flange 68 described later in the radial direction. The center-side recess 59 is recessed toward the first direction D1. Further, the center-side recess 59 is recessed toward the first direction D1 with respect to the center-side pressing surface 69 of the center-side flange 68. The center-side recess 59 is formed at the same position as the center-side fitting portion 58 in the circumferential direction S. When viewed from the direction D, the end portion in the circumferential direction S of the center-side recess 59 is connected to the center-side cam hole 43H. As shown in FIG. 1, the center-side recess 59 faces the end surface 74D of the annular wall 74A of the pressure plate 70 described later and the end surface 77B on the first direction D1 side of the pressure-side fitting teeth 77 in the direction D. As shown in FIG. 4, the radial length of the center-side recess 59 is L14. In the present embodiment, the radial length L14 of the center-side recess 59 is uniform regardless of the position of the center-side recess 59 in the direction D. However, the radial length of the center-side recess 59 is not limited to this. The radial length of the center-side recess 59 may be, for example, shorter as it goes in the first direction D1. The radial length L14 of the center-side recess 59 is uniform regardless of the position of the center-side recess 59 in the circumferential direction S. However, the radial length of the center-side recess 59 is not limited to this. The radial length of the center-side recess 59 may be, for example, shorter as it goes in the first circumferential direction S1. Note that a part of the center-side recess 59 may penetrate in the direction D, for example.

[0045] As shown in Figure 3, the center flange 68 is located radially outward from the center recess 59. The center flange 68 is located radially outward from the center fitting portion 58. The center flange 68 is formed integrally with the center recess 59. The center pressing surface 69, which is the surface of the center flange 68 on the second direction D2 side, sandwiches the input rotating plate 20 (see Figure 1) and the output rotating plate 22 (see Figure 1) between itself and the pressure plate 70 (see Figure 1). The center pressing surface 69 presses the input rotating plate 20 and the output rotating plate 22. The center pressing surface 69 is located on the second direction D2 side of the center recess 59 than the end (bottom surface) of the first direction D1. As shown in Figure 6, in direction D, the length from the center-side pressing surface 69 to the end 67A of the center-side assist cam surface 60A on the second direction D2 side is length L7. Length L7 is longer than the length L15 (see Figure 11) from the pressure-side pressing surface 98A (see Figure 11) to the end face 77B (see Figure 11) of the pressure-side fitting tooth 77 (see Figure 11) (see also Figure 1). Also, as shown in Figure 1, when the pressure plate 70 is closest to the clutch center 40 and the input-side rotating plate 20 and the output-side rotating plate 22 are pressed against each other, length L7 is longer than the length L18 from the center-side pressing surface 69 to the pressure-side pressing surface 98A (see also Figure 1).

[0046] As shown in Figure 1, the pressure plate 70 is provided so as to be able to move toward and away from the clutch center 40 and to be able to rotate relative to it. The pressure plate 70 is configured to be able to press against the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 70 is positioned concentrically with the clutch center 40 and the clutch housing 30. As shown in Figure 7, the pressure plate 70 comprises a pressure side body portion 72, a pressure side recess 85, and a pressure side flange 98. The pressure side flange 98 is connected to the portion of the pressure side body portion 72 on the second direction D2 side and extends radially outward. The pressure side body portion 72 protrudes more than the pressure side flange 98 in the first direction D1. The pressure plate 70 holds a plurality of output side rotating plates 22 (see Figure 1) which are arranged alternately with the input side rotating plate 20 (see Figure 1).

[0047] As shown in FIG. 7, the pressure-side main body portion 72 includes a cylindrical portion 80, an outer peripheral wall 73, a plurality of pressure-side cam portions 90, a pressure-side fitting portion 88, and a spring accommodating portion 84 (see FIG. 8).

[0048] The cylindrical portion 80 is formed in a cylindrical shape. The cylindrical portion 80 is formed integrally with the pressure-side cam portion 90. The cylindrical portion 80 accommodates the tip portion 15T (see FIG. 1) of the output shaft 15. A release bearing 18 (see FIG. 1) is accommodated in the cylindrical portion 80. The cylindrical portion 80 is a portion that receives the pressing force from the push member 16B (see FIG. 1). Further, the cylindrical portion 80 is a portion that receives the oil flowing out from the tip portion 15T of the output shaft 15.

[0049] As shown in FIG. 7, the outer peripheral wall 73 is disposed radially outside the cylindrical portion 80. The outer peripheral wall 73 extends in the first direction D1. The outer peripheral wall 73 has a cylindrical portion 74 formed in a cylindrical shape centered on the axis of the output shaft 15 (see FIG. 1) and a protruding portion 75. The cylindrical portion 74 has an annular wall 74A and a spline fitting portion 74B provided on the radially outer side of the annular wall 74A. The spline fitting portion 74B has a plurality of pressure-side fitting teeth 77 extending in the direction D, a plurality of spline grooves 78 formed between adjacent pressure-side fitting teeth 77, a plurality of tooth missing portions 76 formed between adjacent pressure-side fitting teeth 77, and an oil discharge hole 79. The tooth missing portion 76 has a longer length in the circumferential direction S than the spline groove 78. The pressure-side fitting teeth 77 hold the output-side rotating plate 22 (see FIG. 1). The plurality of pressure-side fitting teeth 77 are arranged in the circumferential direction S. The pressure-side fitting teeth 77 protrude radially outward from the annular wall 74A. No pressure-side fitting teeth 77 are provided in the tooth missing portion 76. Therefore, the circumferential interval in the circumferential direction S between two pressure-side fitting teeth 77 arranged in the circumferential direction S sandwiching the tooth missing portion 76 is longer than the circumferential interval in the circumferential direction S between two pressure-side fitting teeth 77 arranged in the circumferential direction S sandwiching the spline groove 78. In the present embodiment, the tooth missing portions 76 are provided at three equal intervals along the circumferential direction S.

[0050] The oil discharge hole 79 is formed to penetrate the toothless portion 76 radially. The oil discharge hole 79 connects the inside and outside of the pressure plate 70. The oil discharge hole 79 is a hole that discharges oil that has flowed into the pressure plate 70 from the output shaft 15 (see Figure 1) to the outside of the pressure plate 70. In this embodiment, four oil discharge holes 79 are formed in the toothless portion 76. The four oil discharge holes will also be referred to as oil discharge holes 79L, 79M, 79N1, and 79N2. However, when giving a description common to all of the oil discharge holes 79L, 79M, 79N1, and 79N2, the name oil discharge hole 79 will be used as appropriate. The oil discharge hole 79L, oil discharge hole 79M, and oil discharge holes 79N1 and 79N2 are each formed in one of the three aligned toothless portions 76. The oil discharge hole 79 is located close to the pressure-side assist cam surface 90A on the first circumferential direction S1 side. For example, the distance in the circumferential direction S between the pressure-side assist cam surface 90A, which is located on the second circumferential direction S2 side of the oil discharge hole 79L, and the oil discharge hole 79L is shorter than the distance in the circumferential direction S between the pressure-side slipper cam surface 90S, which is located on the first circumferential direction S1 side of the oil discharge hole 79L, and the oil discharge hole 79L. The same applies to the oil discharge holes 79M, 79N1, and 79N2. The number of oil discharge holes 79 formed in a single toothless portion 76 is not particularly limited. For example, two or more oil discharge holes 79 may be formed in a single toothless portion 76 at positions close to the pressure-side assist cam surface 90A.

[0051] As shown in Figure 11, the oil discharge hole 79L overlaps with the first direction D1 end 95B of the pressure-side assist cam surface 90A in direction D. As shown in Figure 7, the oil discharge holes 79L, 79M, 79N1, and 79N2 are formed at positions offset from each other in direction D. However, the position of the oil discharge holes 79 in direction D is not particularly limited. Some of the oil discharge holes 79 may be aligned with each other in direction D, or all of the oil discharge holes 79 may be aligned with each other in direction D. The oil discharge holes 79L, 79M, and 79N1 are arranged at approximately equal intervals along the circumferential direction S. However, the oil discharge holes 79 do not have to be arranged at approximately equal intervals along the circumferential direction S. Some of the pressure-side fitting teeth 77 are arranged at equal intervals. For example, the pressure-side fitting teeth 77 arranged between the oil discharge hole 79L and the oil discharge hole 79M are arranged at equal intervals.

[0052] As shown in Figures 7 and 8, the pressure-side main body portion 72 has through holes 89 located in the missing tooth portion 76 and penetrating in direction D. Three through holes 89 are arranged at equal intervals in the circumferential direction S (see also Figure 10). In plan view, the through holes 89 are formed in the same shape as the pressure-side mating teeth 77. Therefore, the radial length and circumferential length S of the through holes 89 are formed in the same way as the radial length and circumferential length S of the pressure-side mating teeth 77. As shown in Figure 8, the through holes 89 are formed in a substantially trapezoidal shape when viewed from direction D. More specifically, the circumferential length S of the radially inner edge 89a of the through hole 89 is longer than the circumferential length S of the radially outer edge 89b of the through hole 89 (see also Figure 14). Furthermore, as shown in Figure 7, the spacing between adjacent through holes 89 and pressure-side fitting teeth 77 in the circumferential direction S is equal to the spacing between two adjacent pressure-side fitting teeth 77 in the circumferential direction S, separated by a spline groove 78 (see also Figure 10). The through holes 89 are formed in the circumferential direction S at a position that overlaps with at least a portion of the oil discharge holes 79. Therefore, a portion of the oil that flows out from the oil discharge holes 79 lubricates the input-side rotating plate 20 and the output-side rotating plate 22, then passes through the through holes 89 and is discharged to the outside of the pressure plate 70.

[0053] As shown in Figure 7, the pressure plate 70 has a projection 75 that extends in the first direction D1 from the cylindrical portion 74, specifically from the pressure-side fitting teeth 77, and from the end face of the cylindrical portion 74 on the first direction D1 side, specifically from the end face 77B of the pressure-side fitting teeth 77 on the first direction D1 side. The projection 75 is connected to the end face 77B of some of the pressure-side fitting teeth 77 on the first direction D1 side. The end face 77B of the pressure-side fitting teeth 77 on the first direction D1 side refers to the end face on the first direction D1 side of the pressure-side fitting teeth 77 to which the projection 75 is not connected. In this embodiment, the end face 74D of the annular wall 74A on the first direction D1 side and the end face 77B of the pressure-side fitting teeth 77 on the first direction D1 side are flush. Therefore, "the end face of the cylindrical portion 74 on the first direction D1 side" refers to the end face 74D of the annular wall 74A and the end face 77B of the pressure-side fitting tooth 77. However, if the end face 74D of the annular wall 74A and the end face 77B of the pressure-side fitting tooth 77 are offset from each other in direction D, then "the end face of the cylindrical portion 74 on the first direction D1 side" refers to the end face of the annular wall 74A and the end face 77B of the pressure-side fitting tooth 77 that is located on the first direction D1 side. Figure 9 is an enlarged view of the vicinity of the protruding portion 75 in Figure 1. As shown in Figure 9, the annular wall 74A includes a first annular portion 74A1 that forms part of the spring housing portion 84 described later, and a second annular portion 74A2 that extends from the first annular portion 74A1 toward the first direction D1 side. The second annular portion 74A2 is connected to the end of the first annular portion 74A1 on the first direction D1 side and extends further toward the first direction D1 side than the first annular portion 74A1. Pressure-side mating teeth 77 are formed on the first annular portion 74A1 and the second annular portion 74A2. The position of the end face 77B of the pressure-side mating teeth 77 on the first direction D1 side (see also Figure 1) is the same as the position of the end of the second annular portion 74A2 on the first direction D1 side. The position of the end face 77A of the pressure-side mating teeth 77 on the second direction D2 side is the same as the position of the end of the first annular portion 74A1 on the second direction D2 side. As shown in Figure 9, the inner circumferential surface 74C1 of the first annular portion 74A1 is located radially inward than the inner circumferential surface 74C2 of the second annular portion 74A2.As shown in Figure 9, the radial thickness H1 of the first annular portion 74A1 is greater than the radial thickness H2 of the second annular portion 74A2.

[0054] As shown in Figure 7, the protrusions 75 are formed to protrude in the first direction D1 from the end face 77B of the pressure-side fitting teeth 77 and the end face 74D of the annular wall 74A (i.e., the end face of the cylindrical portion 74 on the first direction D1 side). As shown in Figure 10, the protrusions 75 are formed at three locations in the circumferential direction S. The protrusions 75 are arranged at equal intervals in the circumferential direction S. When the clutch center 40 (see Figure 3) and the pressure plate 70 are assembled (see also Figure 16), at least a portion of the protrusions 75 are positioned inside the center-side cam hole 43H (see Figure 5) when viewed from direction D. The protrusions 75 may be formed separately from the cylindrical portion 74. The outer peripheral wall 73 has three protrusions 75, but the number of protrusions 75 is not limited to three. Also, the protrusions 75 do not have to be arranged at equal intervals in the circumferential direction S. The protruding portion 75 may be connected across the end face 74D of the annular wall 74A on the first direction D1 side shown in Figure 7 and the end face 77B of the pressure-side fitting tooth 77 on the first direction D1 side, or it may be connected only to the end face 74D of the annular wall 74A on the first direction D1 side.

[0055] The projection 75 extends toward the first direction D1 and is a member having a substantially pyramidal shape when viewed from direction D (see also Figure 11). The projection 75 has a shape that tapers towards the first direction D1. As shown in Figure 9, the projection 75 has a slope 75S1. The slope 75S1 forms the radially outer circumferential surface of the projection 75. The slope 75S1 extends from the end face 77B of the pressure-side fitting tooth 77 toward the first direction D1 toward the end face 75A of the projection 75 toward the first direction D1. The slope 75S1 extends radially inward toward the first direction D1 and is inclined with respect to the axial direction. The projection 75 is formed in a shape in which the radial length becomes shorter toward the first direction D1. Also, as shown in Figure 10, the projection 75 has slopes 75S2 and 75S3. The inclined surfaces 75S2 and 75S3 extend from the end face 77B of the pressure-side fitting tooth 77 (see Figure 9) on the first direction D1 side toward the end face 75A of the projection 75 (see Figure 9). The inclined surface 75S2 is located on the first circumferential direction S1 side with respect to the end face 75A of the projection 75. The inclined surface 75S3 is located on the second circumferential direction S2 side with respect to the end face 75A of the projection 75. The projection 75 is formed in a shape in which the length in the circumferential direction S becomes shorter as it approaches the first direction D1 (see also Figure 7). In this embodiment, the end face 75A of the projection 75 is located inside the center-side cam hole 43H (see Figure 16). However, the end face 75A of the projection 75 may be located on the first direction D1 side of the center-side cam hole 43H. As shown in Figure 7, the circumferential length of one projection 75 is formed to be approximately the same as that of one pressure-side mating tooth 77.

[0056] As shown in Figure 2, when the rotational axes of the clutch housing 30, the output rotating plate 22, and the pressure plate 70 are located coaxially (i.e., on the axis CL (see Figure 1)), the radial distance between the edge of the inclined surface 75S1 on the first direction D1 side (see also Figure 9) and the inner peripheral edge 22N of the output rotating plate 22 is distance L21. Distance L21 is longer than the radial distance L20 between the inner peripheral surface 33N of the side wall 33 (see Figure 1) and the outer peripheral edge 22U of the output rotating plate 22. Note that it is not necessary for L21 > L20 to hold for all of the multiple output rotating plates 22. At a minimum, it is sufficient that L21 > L20 holds between the output rotating plate 22 located furthest towards the first direction D1 and the side wall 33. The radial distance between the outer circumferential surface 77U of the pressure-side mating teeth 77 and the inner circumferential edge 22N of the output-side rotating plate 22 is length L22. Length L22 is shorter than the radial distance L20 between the inner circumferential surface 33N of the side wall 33 and the outer circumferential edge 22U of the output-side rotating plate 22, as shown in Figure 2.

[0057] As shown in Figure 10, the circumferential length S of one projection 75 is W1. In this embodiment, the pressure plate 70 has three projections 75, so the total length obtained by summing the circumferential lengths S of the projections 75 is 3 × W1. Here, let W2 be the length of half the circumference of the annular wall 74A. In this case, the total length 3 × W1 obtained by summing the circumferential lengths S of the projections 75 is shorter than the length W2 of half the circumference of the cylindrical portion 74.

[0058] The pressure-side cam portion 90 shown in Figure 7 is formed in a trapezoidal shape with cam surfaces 90A and 90S that are inclined surfaces. The pressure-side cam portion 90, together with the center-side cam portion 60 (see Figure 3), forms an assist & slipper (registered trademark) mechanism that slides against each other to generate assist torque or slipper torque. The pressure-side cam portion 90 protrudes from the pressure-side flange 98 in the first direction D1. The pressure-side cam portions 90 are arranged at equal intervals in the circumferential direction S of the pressure plate 70. In this embodiment, the pressure plate 70 has three pressure-side cam portions 90, but the number of pressure-side cam portions 90 is not limited to three.

[0059] The pressure-side cam portion 90 is located radially outward from the cylindrical portion 80. The pressure-side cam portion 90 includes a pressure-side assist cam portion 91 including a pressure-side assist cam surface 90A, a pressure-side slipper cam portion 92 including a pressure-side slipper cam surface 90S, and a pressure-side cam body portion 93 located between the pressure-side assist cam portion 91 and the pressure-side slipper cam portion 92. The pressure-side assist cam portion 91, the pressure-side cam body portion 93, and the pressure-side slipper cam portion 92 are integrally formed. In this embodiment, the pressure plate 70 rotates in the direction from the pressure-side cam body portion 93 toward the pressure-side assist cam portion 91 (i.e., the first circumferential direction S1). The pressure-side cam body portion 93 is located on the opposite side of the rotation direction of the pressure plate 70 (i.e., the first circumferential direction S1) from the pressure-side assist cam portion 91. The pressure-side cam body portion 93 is located relative to the pressure-side slipper cam portion 92 on the side of the rotational direction of the pressure plate 70 (i.e., the first circumferential direction S1). The pressure-side assist cam surface 90A is configured to be in contact with the center-side assist cam surface 60A (see Figure 3). The pressure-side assist cam surface 90A is configured to generate a force that moves the pressure plate 70 closer to the clutch center 40 in order to increase the pressing force (contact force) between the input-side rotating plate 20 (see Figure 1) and the output-side rotating plate 22 (see Figure 1) when the pressure plate 70 rotates relative to the clutch center 40 (see Figure 3). The pressure-side assist cam surface 90A extends toward the first circumferential direction S1 as it moves toward the first direction D1, and is inclined with respect to the axial direction. The pressure-side slipper cam surface 90S is configured to be in contact with the center-side slipper cam surface 60S (see Figure 3). The pressure-side slipper cam surface 90S is configured to generate a force that separates the pressure plate 70 from the clutch center 40 in order to reduce the pressing force (contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the pressure plate 70 rotates relative to the clutch center 40.In adjacent pressure-side cam portions 90 with respect to the circumferential direction S, the pressure-side assist cam surface 90A of one pressure-side cam portion 90L and the pressure-side slipper cam surface 90S of the other pressure-side cam portion 90M are arranged opposite each other in the circumferential direction S. The pressure-side slipper cam surface 90S is located on the opposite side of the pressure-side assist cam surface 90A, with the pressure-side cam body portion 93 in between. The pressure-side slipper cam surface 90S extends toward the first circumferential direction S1 as it moves toward the first direction D1, and is inclined with respect to the axial direction. The surface 90E of the pressure-side cam portion 90 on the first direction D1 side is formed flat from the end of the pressure-side assist cam surface 90A on the first circumferential direction S1 side to the end of the pressure-side slipper cam surface 90S on the first circumferential direction S1 side.

[0060] As shown in Figure 7, a main inner surface 93N is formed on the pressure-side cam body 93. A sub-inner surface 91A is formed on the pressure-side cam portion 90. The sub-inner surface 91A is connected to the pressure-side assist cam surface 90A. The sub-inner surface 91A extends radially inward as it moves toward the first direction D1 and is inclined with respect to the axial direction. That is, the sub-inner surface 91A is inclined to move radially outward from the main inner surface 93N as it moves toward the second direction D2. The sub-inner surface 91A may also be parallel to the axis of the output shaft 15. Of the main inner surface 93N, at least the side facing the sub-inner surface 91A (i.e., the side facing the first circumferential direction S1) is inclined to move radially inward from the sub-inner surface 91A as it moves toward the second direction D2. Therefore, the radial length of the pressure-side assist cam surface 90A increases as it moves toward the first direction D1. Here, as shown in Figure 10, the longest radial length of the pressure-side assist cam surface 90A is defined as length L8. The longest radial length of the pressure-side slipper cam surface 90S is defined as length L9. Length L8 is the same as length L9. The midpoint in the radial direction at the end of the first direction D1 of the pressure-side assist cam surface 90A coincides with the midpoint in the radial direction at the end of the first direction D1 of the pressure-side slipper cam surface 90S. The arc AR3, centered on axis CL and passing through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side assist cam surface 90A, also passes through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side slipper cam surface 90S. Note that lengths L8 and L9 may be different. Length L8 may be longer than length L9. If length L8 is longer than length L9, the inner diameter end of the pressure-side assist cam surface 90A at the end of the first direction D1 may be positioned on the inner diameter side of the pressure-side slipper cam surface 90S at the end of the first direction D1.In this case, the arc AR3, which is centered on axis CL and passes through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side assist cam surface 90A, and the arc, which is centered on axis CL and passes through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side slipper cam surface 90S, may be offset in the radial direction. That is, the arc AR3, which is centered on axis CL and passes through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side assist cam surface 90A, may be located on the inner diameter side of the arc, which is centered on axis CL and passes through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side slipper cam surface 90S. The radial length of the end of the first direction D1 of the pressure-side assist cam surface 90A may be the same as the radial length of the end of the first direction D1 of the pressure-side slipper cam surface 90S. In this case, when viewed in the direction of the axis CL, the arc AR3, centered on the axis CL and passing through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side assist cam surface 90A, may also pass through the midpoint in the radial direction at the end of the first direction D1 of the pressure-side slipper cam surface 90S.

[0061] As shown in Figure 12, the pressure-side assist cam surface 90A extends in direction D to the second direction D2 side beyond the pressure-side flange 98. More specifically, the pressure-side assist cam surface 90A extends to the second direction D2 side beyond the outer surface 98B, which will be described later. That is, the end 95 of the pressure-side assist cam surface 90A on the second direction D2 side is located on the second direction D2 side beyond the pressure-side flange 98. As described above, the pressure-side fitting teeth 77 are provided on the pressure-side main body portion 72 which extends in the first direction D1 side beyond the pressure-side flange 98. Therefore, the end 95 of the pressure-side assist cam surface 90A is located on the second direction D2 side beyond the end face 77A of the pressure-side fitting teeth 77 on the second direction D2 side. Furthermore, as shown in Figure 1, the end 95 of the pressure-side assist cam surface 90A on the second direction D2 side is located on the second direction D2 side of the input-side rotating plate 20A, which is the input-side rotating plate 20 located furthest to the second direction D2 among the input-side rotating plates 20, and the outermost output-side rotating plate 22A, which is the output-side rotating plate 22 located furthest to the second direction D2 among the output-side rotating plates 22. That is, the end 95 of the pressure-side assist cam surface 90A is located on the second direction D2 side of the rotating plate (output-side rotating plate 22 in Figure 1) located furthest to the second direction D2 among the multiple input-side rotating plates 20 and multiple output-side rotating plates 22. On the other hand, as shown in Figure 12, the pressure-side slipper cam surface 90S is located on the first direction D1 side of the pressure-side flange 98 in direction D. Therefore, the end 95 of the pressure-side assist cam surface 90A is located on the second direction D2 side of the pressure-side slipper cam surface 90S than the end 96 on the second direction D2 side. Also, the end 95 of the pressure-side assist cam surface 90A is connected to the end surface 90D (see Figure 8) of the pressure-side cam portion 90 on the second direction D2 side. In other words, the end 95 of the pressure-side assist cam surface 90A is the end of the pressure-side cam portion 90 on the second direction D2 side.

[0062] In direction D, the length L10 of the pressure-side assist cam surface 90A and the length L11 of the center-side slipper cam surface 60S are different. Here, length L10 is longer than length L11. Also, as shown in Figure 12, the length L12 of the pressure-side assist cam surface 90A in the inclined surface direction is longer than the length L19 of the pressure-side slipper cam surface 90S in the inclined surface direction. Therefore, the areas of the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S are different. Here, the area of ​​the pressure-side assist cam surface 90A is larger than that of the pressure-side slipper cam surface 90S. However, it is not necessary for both conditions L10 > L11 and L12 > L19 to be met; only one of the conditions may be met. Even in such a case, the area of ​​the pressure-side assist cam surface 90A can be made larger than the area of ​​the pressure-side slipper cam surface 90S. The area of ​​the pressure-side assist cam surface 90A is 1.5 to 3 times the area of ​​the pressure-side slipper cam surface 90S. Preferably, the area of ​​the pressure-side assist cam surface 90A is 1.5 to 2.5 times the area of ​​the pressure-side slipper cam surface 90S. In this embodiment, the end 95B of the pressure-side assist cam surface 90A on the first direction D1 side and the end 96B of the pressure-side slipper cam surface 90S on the first direction D1 side are located in approximately the same position in direction D. However, in order to make the area of ​​the pressure-side assist cam surface 90A larger than that of the pressure-side slipper cam surface 90S, the end 95B of the pressure-side assist cam surface 90A on the first direction D1 side may be positioned further towards the first direction D1 than the end 96B of the pressure-side slipper cam surface 90S on the first direction D1 side.

[0063] Here, the operation of the center-side cam portion 60 (see Figure 3) and the pressure-side cam portion 90 will be explained. When the engine speed increases and the clutch is turned ON, the push member 16B shown in Figure 1 moves to the first direction D1, and the input-side rotating plate 20 and the output-side rotating plate 22 are pressed against each other, and the rotational driving force of the input shaft is transmitted to the output shaft 15. At this time, the pressure plate 70 is in the state where it has moved to the first direction D1, that is, the state where it is closest to the clutch center 40. Also at this time, the center-side assist cam surface 60A of the center-side cam portion 60 (see Figure 3) and the pressure-side assist cam surface 90A of the pressure-side cam portion 90 (see Figure 7) are in contact with each other. When the clutch is ON, the rotational driving force input to the input gear 35 and clutch housing 30 shown in Figure 1 can be transmitted to the output shaft 15 via the clutch center 40. At this time, as shown in Figure 13A, a first rotational force in the circumferential direction S1 is applied to the pressure plate 70. As a result, due to the action of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, a force in the first direction D1 is generated on the pressure plate 70. This increases the pressure contact force between the input-side rotating plate 20 and the output-side rotating plate 22.

[0064] On the other hand, when the rotational speed of the output shaft 15 shown in Figure 1 exceeds the rotational speed of the input gear 35 and the clutch housing 30, back torque is generated. In this case, as shown in Figure 13B, a first circumferential rotational force S1 is applied to the clutch center 40. As a result, the contact force between the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 1) is released by the action of the center side slipper cam surface 60S and the pressure side slipper cam surface 90S. This makes it possible to avoid malfunctions in the engine and transmission caused by back torque.

[0065] As shown in Figure 7, the pressure-side fitting portion 88 is located radially outward from the pressure-side cam portion 90. The pressure-side fitting portion 88 is located on the first direction D1 side of the pressure-side cam portion 90. As shown in Figure 9, the pressure-side fitting portion 88 is the portion of the second annular portion 74A2 of the annular wall 74A that extends from the end on the first direction D1 side to the second direction D2. The second annular portion 74A2 extends from the bottom surface 84A of the spring housing portion 84, which will be described later, to the first direction D1 side. The spring housing portion 84 houses the clutch spring 25, which will be described later. Therefore, the pressure-side fitting portion 88 is located on the first direction D1 side of the bottom surface 84A of the spring housing portion 84 and the end 25A of the clutch spring 25 on the first direction D1 side. The pressure-side fitting portion 88 is configured to be externally fitted to the center-side fitting portion 58 so as to be slidable in direction D. The cylindrical portion 74 is externally fitted to the center-side fitting portion 58. However, the pressure-side fitting portion 88 may also be internally fitted to the center-side fitting portion 58.

[0066] In the radial direction of the pressure plate 70, the length from the spline groove 78 (see Figure 9) to the outer circumferential surface 77U of the pressure-side fitting teeth 77, i.e., the height of the pressure-side fitting teeth 77, is length L13. The radial length of the cylindrical portion 74 is length L26. The radial length L14 of the center-side recess 59 is longer than lengths L13 and L26.

[0067] As shown in Figure 14, a spring-side recess 94 is formed in the pressure-side cam portion 90. The spring-side recess 94 is formed on the second direction D2 side of the pressure-side slipper cam surface 90S of the pressure-side cam portion 90 (see also Figure 8). The spring-side recess 94 is formed in connection with the pressure-side cam hole 73H, which will be described later, and the spring housing portion 84, which will be described later. The spring-side recess 94 is connected to the spring housing portion 84 on the first circumferential direction S1 side and to the pressure-side cam hole 73H on the second circumferential direction S2 side. The spring-side recess 94 has a shape that is cut out from the end face 90D on the second direction D2 side of the pressure-side cam portion 90 toward the first direction D1 side, and is a recessed portion toward the first direction D1 side. The radial length of the spring-side recess 94 is formed to be shorter than the radial length of the spring housing portion 84, which will be described later. Furthermore, the length of the spring-side recess 94 in direction D is less than half the length of the clutch spring 25 in direction D, which will be described later.

[0068] As shown in Figure 7, the pressure-side recess 85 is formed radially outward from the outer edge of the outer peripheral wall 73. The pressure-side recess 85 is connected to the outer peripheral wall 73 and the pressure-side flange 98. The pressure-side recess 85 is recessed toward the second direction D2 side than the pressure-side pressing surface 98A of the pressure-side flange 98, which will be described later. The pressure-side recess 85 is formed over the circumferential direction S. As shown in Figure 1, a judder spring 120 is housed in the pressure-side recess 85. The judder spring 120 is held by the pressure plate 70. The inner peripheral edge of the judder spring 120 abuts against the outer peripheral surface of the pressure-side mating teeth 77 and is held by the pressure-side mating teeth 77. The judder spring 120 is held so as to be movable relative to the pressure-side mating teeth 77 in direction D and relative to the circumferential direction S. The judder spring 120 is aligned in direction D with the output-side rotating plate 22 held by the pressure plate 70. The judder spring 120 is provided so as to be in contact with the output-side rotating plate 22 held by the pressure plate 70. In this embodiment, the judder spring 120 is positioned between the outermost output-side rotating plate 22A of the output-side rotating plates 22 held by the pressure plate 70 and the pressure-side flange 98. An iron sheet material 122 is positioned between the judder spring 120 and the pressure-side flange 98. As a result, the judder spring 120 does not directly contact the pressure-side flange 98, thereby suppressing wear of the pressure-side flange 98, which is made of aluminum alloy. The judder spring 120 may be, for example, a disc spring or a wave spring.

[0069] As shown in Figure 7, the pressure-side flange 98 is connected to the pressure-side recess 85 and is located radially outward from the pressure-side body portion 72. The pressure-side flange 98 is integrally formed with the pressure-side body portion 72 and the pressure-side recess 85. That is, the pressure-side flange 98 is connected to the pressure-side body portion 72 via the pressure-side recess 85. The pressure-side pressing surface 98A, which is the surface of the pressure-side flange 98 on the first direction D1 side, presses against the output-side rotating plate 22 (see Figure 1). The outer surface 98B (see Figure 11), which is the surface of the pressure-side flange 98 on the second direction D2 side, is formed parallel to the pressure-side pressing surface 98A in direction D. As shown in Figure 11, the length from the pressure-side pressing surface 98A to the end face 77B of the pressure-side fitting tooth 77 on the first direction side in direction D is length L15. The pressure-side flange 98 may also be directly connected to the pressure-side main body 72.

[0070] As shown in Figure 14, the pressure plate 70 has a pressure-side cam hole 73H that penetrates a part of the pressure-side main body portion 72 in direction D. The pressure-side cam hole 73H is located radially outward from the cylindrical portion 80. The pressure-side cam hole 73H is formed between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S of adjacent pressure-side cam portions 90. As shown in Figure 14, when viewed from direction D, a part of the pressure-side assist cam surface 90A is located inside the pressure-side cam hole 73H. The pressure-side cam hole 73H has a first portion 73HA and a second portion 73HB. The first portion 73HA is located on the first circumferential direction S1 side of the pressure-side cam hole 73H from a position approximately midway in the circumferential direction S. The second portion 73HB is located on the second circumferential direction S2 side of the first portion 73HA. The first portion 73HA has a radially inner edge 74N and a radially outer edge 74U. In the radial direction, the distance between edge 74N and edge 74U is length L16. The second portion 73HB has a radially inner edge 75N and a radially outer edge 75U. In the radial direction, the distance between edge 75N and edge 75U is length L17. Edge 75N of the second portion 73HB is located inward of edge 74N of the first portion 73HA in the radial direction of the pressure plate 70. Edge 75U of the second portion 73HB is located outward of edge 74N of the first portion 73HA in the radial direction of the pressure plate 70. Therefore, the radial length L17 of the second portion 73HB is longer than the radial length L16 of the first portion 73HA.

[0071] As shown in Figures 8 and 14, the spring housing portion 84 is formed in a cylindrical shape that is recessed in the first direction D1 from the end face 90D of the pressure-side cam portion 90. As shown in Figure 9, the inner circumferential surface 74C1 of the first annular portion 74A1 constitutes the portion of the inner circumferential surface of the spring housing portion 84 that is located radially outward. The spring housing portion 84 is formed in a substantially circular shape when viewed from direction D (see Figure 14). The spring housing portion 84 is the portion that houses the clutch spring 25. As shown in Figure 14, the spring housing portion 84 is connected to the spring-side recess 94. As described above, the spring-side recess 94 has a shape that is cut out toward the first direction D1. Therefore, the portion of the spring housing portion 84 that is connected to the spring-side recess 94 is formed to be shorter in length in direction D compared to the other portions of the spring housing portion 84. The spring housing portion 84 is connected to the pressure-side cam hole 73H via the spring-side recess 94. As shown in Figure 9, the spring housing portion 84 has a bottom surface 84A. The bottom surface 84A is located on the side of the first direction D1 than the intermediate position 77P in direction D of the pressure-side mating teeth 77.

[0072] The clutch spring 25 is housed in the spring housing 84. The clutch spring 25 biases the pressure plate 70 toward the clutch center 40 (i.e., toward the first direction D1). The clutch spring 25 is, for example, a coil spring made of spring steel wound in a spiral shape. The end 25A of the clutch spring 25 toward the first direction D1 is in contact with the bottom surface 84A of the spring housing 84. This biases the pressure plate 70 toward the clutch center 40.

[0073] As shown in Figure 1, the first spring 130A and the second spring 130B are expandable and contractible relative to direction D and are held by the pressure plate 70. In this embodiment, as shown in Figures 15A and 15B, the first spring 130A and the second spring 130B are, for example, wave springs, but are not limited to wave springs and may be elastic members such as rubber or springs such as disc springs. As shown in Figure 1, the first spring 130A is positioned between adjacent output-side rotating plates 22 held by the pressure plate 70. The first spring 130A is provided so as to be in contact with the output-side rotating plates 22 held by the pressure plate 70. Here, as shown in Figure 9, the output-side rotating plate 22 held by the pressure plate 70 that is in contact with the first spring 130A and is located on the first direction D1 side of the first spring 130A is referred to as the output-side rotating plate 22PA. The input side rotating plate 20, which is adjacent to the output side rotating plate 22PA and located on the second direction D2 side of the output side rotating plate 22PA, is designated as the input side rotating plate 20PA. The first spring 130A is configured to prevent the output side rotating plate 22PA and the input side rotating plate 20PA from coming into contact when the center side assist cam surface 60A (see Figure 1) and the pressure side assist cam surface 90A (see Figure 1) come into contact (for example, when the clutch has moved from a disengaged state to a partial clutch state). That is, the first spring 130A creates a gap between the output side rotating plate 22PA and the input side rotating plate 20PA when the center side assist cam surface 60A and the pressure side assist cam surface 90A come into contact. The term "half-clutch state" refers to a state in which the driver operates the clutch by gripping the clutch lever or pressing a shift button, causing slippage between the input-side rotating plate 20 and the output-side rotating plate 22, and the rotational driving force transmitted from the input shaft to the output shaft 15 (see Figure 1) is greater than 0% but less than 100% of the rotational driving force transmitted to the input shaft. The term "at least a part of the half-clutch state" refers to, for example, the region in which the rotational driving force transmitted from the input shaft to the output shaft 15 is greater than 0% but 50% or less (for example, 80% or less) of the rotational driving force transmitted to the input shaft.When the center-side assist cam surface 60A and the pressure-side assist cam surface 90A come into contact, the output-side rotating plate 22, which is located on the second direction D2 side of the output-side rotating plate 22PA, and the input-side rotating plate 20, which is located between them, are pressed against each other, allowing power to be transmitted from the input-side rotating plate 20 to the output-side rotating plate 22. The first spring 130A gradually releases, for example, the clutch lever held by the driver, and when the set load of the clutch spring 25 exceeds the set load of the first spring 130A, it allows contact between the output-side rotating plate 22PA and the input-side rotating plate 20PA.

[0074] The second spring 130B is positioned between the output-side rotating plate 22 held by the pressure plate 70 and the pressure plate 70. The second spring 130B is positioned between adjacent output-side rotating plates 22 held by the pressure plate 70. The second spring 130B is held by the pressure plate 70 and is provided to be in contact with the output-side rotating plate 22 located furthest towards the second direction D2 and the output-side rotating plate 22 located further towards the first direction D1. Here, the output-side rotating plate 22 held by the pressure plate 70 that is in contact with the second spring 130B and located further towards the first direction D1 than the second spring 130B is referred to as the output-side rotating plate 22PB. The input-side rotating plate 20 adjacent to the output-side rotating plate 22PB and located further towards the second direction D2 than the output-side rotating plate 22PB is referred to as the input-side rotating plate 20PB. The second spring 130B is configured to prevent contact between the output-side rotating plate 22PB and the input-side rotating plate 20PB when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A come into contact. That is, the second spring 130B creates a gap between the output-side rotating plate 22PB and the input-side rotating plate 20PB when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A come into contact. The second spring 130B allows contact between the output-side rotating plate 22PB and the input-side rotating plate 20PB when, for example, the driver gradually releases the clutch lever they are holding and the set load of the clutch spring 25 exceeds the set load of the second spring 130B. Note that the clutch device 10 (see Figure 1) may be equipped with only one of the first spring 120A and the second spring 130B.

[0075] In the above configuration, since the contact between at least a portion of the output-side rotating plate 22 held by the pressure plate 70 and the input-side rotating plate 20 is suppressed, it is possible to suppress the sudden application of cam thrust to the input-side rotating plate 20 and the output-side rotating plate 22. As a result, it is possible to suppress a sudden increase in the contact force between the input-side rotating plate 20 and the output-side rotating plate 22.

[0076] Figure 16 shows the clutch center 40 and the pressure plate 70 assembled. In the state shown in Figure 16, the pressure-side fitting portion 88 (see Figure 7) is fitted onto the center-side fitting portion 58 (see Figure 3). At this time, the pressure-side assist cam surface 90A and the center-side assist cam surface 60A are in contact. When the pressure-side assist cam surface 90A and the center-side assist cam surface 60A are in contact, the pressure plate 70 is positioned closest to the first direction D1. As shown in Figure 16, when the clutch center 40 and the pressure plate 70 are assembled, at least a portion of the spline groove 78 is positioned to overlap with the center-side cam hole 43H when viewed from direction D (here, the first direction D1). At this time, when viewed from direction D, the protruding portion 75 of the pressure plate 70 is positioned inside the center-side cam hole 43H. In this embodiment, all of the protrusions 75 are located inside the center-side cam hole 43H, but a portion of the protrusions 75 may also be located inside the center-side cam hole 43H.

[0077] When the pressure-side assist cam surface 90A and the center-side assist cam surface 60A are in contact, as shown in Figure 9, the end face 75A of the protrusion 75 on the first direction D1 side is located on the first direction D1 side of the center-side pressing surface 69. Therefore, a portion of the protrusion 75 is located on the first direction D1 side of the center-side pressing surface 69, and the other portion of the protrusion 75 is located on the second direction D2 side of the center-side pressing surface 69. In other words, a portion of the protrusion 75, which is part of the outer peripheral wall 73, is positioned to overlap with a portion of the center-side recess 59 in the radial direction. Also, a portion of the protrusion 75 overlaps with the center-side cam hole 43H in the radial direction. Since the center-side recess 59 is located on the first direction D1 side of the center-side cam portion 60 (see Figure 3) and the center-side fitting portion 58, as shown in Figure 1, a part of the outer peripheral wall 73 is located on the first direction D1 side of the end 60E of the center-side cam portion 60 on the first direction D1 side. Also, of the outer peripheral wall 73, all but a part of the protruding portion 75 are located on the second direction D2 side of the center-side pressing surface 69.

[0078] The length L7 from the center-side pressing surface 69 to the second-direction D2 end 67A of the center-side assist cam surface 60A is longer than the length L15 from the pressure-side pressing surface 98A to the first-direction end face 77B of the pressure-side fitting tooth 77. Therefore, when the clutch center 40 and the pressure plate 70 are assembled, the second-direction D2 end 67A of the center-side assist cam surface 60A is located on the first-direction D1 side of the pressure-side pressing surface 98A. Here, when the pressure-side assist cam surface 90A and the center-side assist cam surface 60A are in contact, the second-direction D2 end 67A of the center-side assist cam surface 60A, when viewed along the axis of the output shaft 15, coincides with the pressure-side cam hole 73H (see also Figure 14) and is located on the second-direction D2 side of the outer surface 98B of the pressure-side flange 98. Furthermore, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is positioned further to the second direction D2 than the end face 77A of the pressure-side fitting tooth 77 on the second direction D2 side. Also, in this case, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is positioned further to the second direction D2 than the outermost input-side rotating plate 20A and the outermost output-side rotating plate 22A. That is, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is positioned further to the second direction D2 than the rotating plate (output-side rotating plate 22 in Figure 1) that is located furthest to the second direction D2 among the multiple input-side rotating plates 20 and multiple output-side rotating plates 22.

[0079] Furthermore, the position of the pressure plate 70 and the clutch center 40 in direction D when the pressure-side slipper cam surface 90S (see Figure 17) and the center-side slipper cam surface 60S (see Figure 17) begin to make contact does not change from the position when the pressure-side assist cam surface 90A and the center-side assist cam surface 60A make contact. Figure 17 is a cross-sectional view of the clutch device 10 when the pressure-side slipper cam surface 90S and the center-side slipper cam surface 60S begin to make contact. As shown in Figure 17, when the pressure-side slipper cam surface 90S and the center-side slipper cam surface 60S begin to come into contact, and when the pressure plate 70 is moving in the second direction D2 due to the action of the pressure-side slipper cam surface 90S and the center-side slipper cam surface 60S, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is positioned further to the second direction D2 than the end face 77A of the pressure-side fitting tooth 77 on the second direction D2 side. Also, at this time, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is positioned further to the second direction D2 than the outermost input-side rotating plate 20A and the outermost output-side rotating plate 22A. In other words, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located on the second direction D2 side of the multiple input-side rotating plates 20 and multiple output-side rotating plates 22 that is located furthest to the second direction D2 side (in Figure 17, the output-side rotating plate 22).

[0080] Figure 18 is a cross-sectional view of the clutch device 10 in a half-clutch state. When the clutch device 10 is in a "half-clutch state," the pressure plate 70 is located in a second direction D2 side than the state in which it is closest to the clutch center 40 and pressing against the input-side rotating plate 20 and the output-side rotating plate 22, and is located in a first direction D1 side than the state in which it is in contact with the stopper plate 100. As shown in Figure 18, in the half-clutch state, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located in a second direction D2 side than the end face 77A of the pressure-side fitting teeth 77 on the second direction D2 side. Also, at this time, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located in a second direction D2 side than the outermost input-side rotating plate 20A and the outermost output-side rotating plate 22A. In other words, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located further towards the second direction D2 than the rotating plate (in Figure 18, the output-side rotating plate 22) among the multiple input-side rotating plates 20 and multiple output-side rotating plates 22.

[0081] The stopper plate 100 is provided so as to be in contact with the pressure plate 70. The stopper plate 100 is a member that prevents the pressure plate 70 from moving away from the clutch center 40 in a second direction D2 by a predetermined distance or more. The stopper plate 100 is fixed to the boss portion 54 of the clutch center 40 by bolts 28. A threaded portion 54a into which the bolts 28 are screwed is formed on the inside of the boss portion 54. The pressure plate 70 is attached to the clutch center 40 by tightening the stopper plate 100 to the boss portion 54 with bolts 28 while the clutch spring 25 is arranged in the spring housing portion 84. The stopper plate 100 is formed in a substantially triangular shape in plan view.

[0082] Figure 19 is a cross-sectional view of the clutch device 10 when the pressure plate 70 is in contact with the stopper plate 100. When the pressure plate 70 moves in the second direction, with the pressure-side slipper cam surface 90S and the center-side slipper cam surface 60S in contact, the pressure plate 70 comes into contact with the stopper plate 100. Even when the pressure plate 70 is in contact with the stopper plate 100, the pressure-side slipper cam surface 90S and the center-side slipper cam surface 60S remain in contact. In the state shown in Figure 19, the pressure plate 70 is furthest from the clutch center 40 in the second direction D2. When the pressure plate 70 is in contact with the stopper plate 100, the end face 74D of the annular wall 74A of the pressure plate 70 is located on the first direction D1 side of the end 58D of the center-side fitting portion 58 on the second direction D2 side. At this time, the end face 74D of the annular wall 74A of the pressure plate 70 is located on the second direction D2 side than the center side pressing surface 69 of the center side flange 68. Therefore, the cylindrical portion 74 is located on the second direction D2 side than the center side pressing surface 69. Also, at this time, the end 88E of the pressure side fitting portion 88 on the first direction D1 side is located on the first direction D1 side than the end 58D of the center side fitting portion 58 on the second direction D2 side.

[0083] Furthermore, when the pressure plate 70 is in contact with the stopper plate 100, a portion of the protrusion 75 is located on the first direction D1 side of the center-side pressing surface 69, and the other portion of the protrusion 75 is located on the second direction D2 side of the center-side pressing surface 69. At this time, the end face of the cylindrical portion 74 on the first direction D1 side (here, the end face 74D of the annular wall 74A and the end face 77B of the pressure-side fitting teeth 77) is located on the second direction D2 side of the center-side pressing surface 69. A portion of the protrusion 75 is positioned to overlap with a portion of the center-side recess 59 when viewed along the axis of the output shaft 15. The center-side recess 59 is located on the first direction D1 side of the center-side cam portion 60 and the center-side fitting portion 58 (see also Figure 7). A portion of the outer peripheral wall 73 is located on the first direction D1 side of the end 60E of the center-side cam portion 60 on the first direction D1 side. Even when the pressure plate 70 is located furthest to the first direction D1 side, a portion of the outer peripheral wall 73 and a portion of the pressure-side fitting teeth 77 are located furthest to the first direction D1 side of the end 60E of the center-side cam portion 60 on the first direction D1 side. Therefore, in all states from the state in which the pressure plate 70 is located furthest to the first direction D1 side to the state in which the pressure plate 70 is located furthest to the second direction D2 side, at least a portion of the outer peripheral wall 73 and at least a portion of the pressure-side fitting teeth 77 are located furthest to the first direction D1 side of the end 60E of the center-side cam portion 60 on the first direction D1 side.

[0084] Furthermore, when the pressure plate 70 is in contact with the stopper plate 100, the end face 74D of the annular wall 74A is located on the second direction D2 side of the center-side recess 59. The end face 74D of the annular wall 74A is located on the first direction D1 side of the center-side cam portion 60E on the first direction D1 side. At this time, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located on the second direction D2 side of the pressure-side fitting tooth 77A on the second direction D2 side. Also, at this time, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located on the second direction D2 side of the outermost input-side rotating plate 20A and the outermost output-side rotating plate 22A. In other words, the end 67A of the center-side assist cam surface 60A on the second direction D2 side is located on the second direction D2 side of the multiple input-side rotating plates 20 and multiple output-side rotating plates 22 that is located furthest to the second direction D2 side (the output-side rotating plate 22 in Figure 19).

[0085] Here, the assembly of the clutch center 40 and the pressure plate 70 will be described. The clutch center 40 and the pressure plate 70 are assembled to an engine, for example, that is installed in a motorcycle. The clutch housing 30 and the clutch center 40 are attached to an output shaft 15 that extends horizontally (direction D). The input side rotating plate 20 and the output side rotating plate 22 are attached to the clutch housing 30. The input side rotating plate 20 is attached to the clutch housing 30 by inserting a claw portion formed on its outer edge so as to protrude radially outward into a notch 30C in the clutch housing 30. The pressure plate 70 is assembled by moving toward the clutch center 40, as shown in Figures 20A and 20B. In Figure 20A, since the pressure plate 70 is not assembled to the clutch center 40, the output side rotating plate 22 is biased downward due to its own weight. Figure 20C is a view of Figure 20A from the first direction D1 side. As shown in Figure 20C, the upper part of the output-side rotating plate 22 is spaced downward from the upper part of the clutch housing 30, and the lowest end 22D of the output-side rotating plate 22 is supported by the inner circumferential surface 33N of the lower part of the clutch housing 30. Figure 20C shows a straight line SL1 passing through the lowest end 22D of the output-side rotating plate 22 and the axis CL of the output shaft 15 (see Figure 1), and a straight line SL2 perpendicular to straight line SL1 and passing through axis CL. Among the rotating plate grooves 22c of the output-side rotating plate 22, the rotating plate groove 22cU that passes through straight line SL1 and is located on the opposite side (upward in this case) from the lowest end 22D with respect to straight line SL2 is located radially inward among the multiple rotating plate grooves 22c. Here, the rotating plate groove 22cU is located furthest upward among the multiple rotating plate grooves 22C. At this time, the protrusion 75 is also located on the opposite side of the lowest end 22D with respect to straight line SL2. When the rotational axes of the clutch housing 30 and the pressure plate 70 are located coaxially (i.e., on axis CL), the edge 75E of the inclined surface 75S1 (see Figure 20B) on the first direction D1 side is located inside the rotating plate groove 22cU.Thus, with the lowest end 22D of the output-side rotating plate 22 supported by the inner circumferential surface 33N of the lower part of the clutch housing 30, and with the rotational axes of the clutch housing 30 and the pressure plate 70 located coaxially (i.e., on the axis CL), the edge 75E of the inclined surface 75S1 on the first direction D1 side is located inward from the rotating plate groove 22cU located on the opposite side (in this case, upward) from the lowest end 22D with respect to the straight line SL2. Therefore, the pressure plate 70 can be easily assembled to the input-side rotating plate 20 and the output-side rotating plate 22 attached to the clutch housing 30. This is because, as shown in Figure 20A, when the input-side rotating plate 20 and the output-side rotating plate 22 are attached to the clutch housing 30, if the operator moves the pressure plate 70 toward the first direction D1, the projection 75 comes into contact with the inner peripheral edge 22N of the output-side rotating plate 22, as shown in Figure 20B, and the inclined surface 75S1 can push up the output-side rotating plate 22. By the operator moving the pressure plate 70 toward the first direction D1, all of the output-side rotating plates 22 are pushed up by the inclined surface 75S1, and the pressure-side fitting teeth 77 can be inserted into the inner diameter side of the input-side rotating plate 20 and the output-side rotating plate 22. This allows the clutch housing 30, clutch center 40, pressure plate 70, input-side rotating plate 20, and output-side rotating plate 22 to be attached to the engine.

[0086] As shown in Figure 2, when the rotational axes of the clutch housing 30, the output rotating plate 22, and the pressure plate 70 are located coaxially (i.e., on the axis CL (see Figure 1)), the radial distance L21 between the edge 75E (see also Figure 9) on the first direction D1 side of the inclined surface 75S1 and the inner peripheral edge 22N of the output rotating plate 22 is longer than the radial distance L20 between the inner peripheral surface 33N of the side wall 33 and the outer peripheral edge 22U of the output rotating plate 22. The output rotating plate 22 attached to the clutch housing 30 can move radially by up to a distance L20 (see also Figure 20B) due to its own weight, etc. Since the distance L21 is longer than the distance L20, even if the output rotating plate 22 moves radially, the edge 75E of the inclined surface 75S1 is located radially inward from the inner peripheral edge 22N of the output rotating plate 22. At this time, the input-side rotating plate 20 is held in the clutch housing 30 (see Figure 1). In this state, when the operator moves the pressure plate 70 toward the first direction D1, the projection 75 comes into contact with the inner peripheral edge 22N of the output-side rotating plate 22, as shown in Figure 20B, and the output-side rotating plate 22 is pushed up. By the operator moving the pressure plate 70 toward the first direction D1, all of the output-side rotating plates 22 are pushed up by the inclined surface 75S1, and the pressure-side fitting teeth 77 can be easily inserted into the inner diameter side of the input-side rotating plate 20 and the output-side rotating plate 22. This makes it easy and reliable to assemble the clutch housing 30, clutch center 40, pressure plate 70, input-side rotating plate 20, and output-side rotating plate 22. Making the gap L21 longer than the gap L20 is effective in facilitating assembly even when the clutch housing 30 is removed from the engine and the rotational axes of the clutch housing 30, the output-side rotating plate 22, and the pressure plate 70 are extended vertically.

[0087] Oil is supplied to the clutch device 10. The oil flows through the hollow portion 15H of the output shaft 15 shown in Figure 1 into the clutch center 40 and the pressure plate 70, and is then supplied to the input side rotating plate 20 and the output side rotating plate 22 through the gap between the center side fitting portion 58 and the pressure side fitting portion 88, and through the oil discharge hole 79 (see Figure 7). The oil absorbs heat and suppresses wear of the friction material. The clutch device 10 of this embodiment is a so-called wet multi-plate friction clutch device.

[0088] Next, the operation of the clutch device 10 in this embodiment will be described. As described above, the clutch device 10 is positioned between the engine and the transmission of the motorcycle, and the driver operates the clutch lever to transmit and interrupt the rotational driving force of the engine to the transmission.

[0089] In the clutch device 10, if the motorcycle operator does not operate the clutch lever, the clutch release mechanism (not shown) does not press the push rod 16A, so the pressure plate 70 presses the input side rotating plate 20 and the output side rotating plate 22 by the biasing force (elastic force) of the clutch spring 25. As a result, the clutch device 10 enters a state where the input side rotating plate 20 and the output side rotating plate 22 are pressed against each other by the clutch center 40 and the pressure plate 70, that is, the clutch is frictionally coupled and in the ON state. When the clutch is in the ON state, the rotational driving force of the engine is transmitted to the output shaft 15.

[0090] When the clutch is ON, the oil flowing through the hollow portion 15H of the output shaft 15 and flowing out from the tip portion 15T of the output shaft 15 falls or splashes into the cylindrical portion 80 and adheres to it (see arrow F in Figure 1). The oil adhering to the cylindrical portion 80 is guided into the pressure plate 70. As a result, the oil flows out to the outside of the pressure plate 70 through the oil discharge hole 79. The oil also flows out to the outside of the pressure plate 70 through the gap between the center-side fitting portion 58 and the pressure-side fitting portion 88. The oil that flows out to the outside of the pressure plate 70 is then supplied to the input-side rotating plate 20 and the output-side rotating plate 22.

[0091] On the other hand, when the clutch is ON and the motorcyclist operates the clutch lever, the clutch release mechanism (not shown) presses the push rod 16A, causing the pressure plate 70 to be displaced in a direction away from the clutch center 40 (second direction D2) against the biasing force of the clutch spring 25. As a result, the clutch center 40 enters the OFF state, where the frictional connection between the input side rotating plate 20 and the output side rotating plate 22 is released, causing the rotational drive of the output shaft 15 to be dampened or stopped. In other words, the transmission of the engine's rotational driving force to the output shaft 15 is interrupted.

[0092] In the clutch-off state, the oil flowing within the hollow portion 15H of the output shaft 15 and flowing out from the tip portion 15T of the output shaft 15 is guided into the pressure plate 70, similar to the clutch-on state. At this time, the pressure plate 70 is separated from the clutch center 40, so the amount of engagement with the center-side fitting portion 58 and the pressure-side fitting portion 88 is reduced. As a result, the oil in the cylindrical portion 80 flows more actively to the outside of the pressure plate 70 and flows to various parts inside the clutch device 10. In particular, oil can be actively guided between the input-side rotating plate 20 and the output-side rotating plate 22, which are separated from each other.

[0093] Furthermore, when the driver releases the clutch operating lever while the clutch is OFF, the pressure on the pressure plate 70 via the push member 16B by the clutch release mechanism (not shown) is released, and the pressure plate 70 is displaced in a direction (first direction D1) that approaches the clutch center 40 by the biasing force of the clutch spring 25.

[0094] As described above, in the clutch device 10 of this embodiment, the area of ​​the pressure-side assist cam surface 90A and the area of ​​the pressure-side slipper cam surface 90S are different from each other. Here, as shown in Figure 12, the length L10 in direction D of the pressure-side assist cam surface 90A and the length L11 in direction D of the pressure-side slipper cam surface 90S are different from each other. Also, the length L12 in the inclined surface direction of the pressure-side assist cam surface 90A and the length L19 in the inclined surface direction of the pressure-side slipper cam surface 90S are different from each other. Here, depending on the characteristics of the vehicle on which the clutch device 10 is installed, there may be cases where, for example, it is not necessary to increase one of the assist torque, which increases the pressing force between the input-side rotating plate 20 (see Figure 1) and the output-side rotating plate 22 (see Figure 1), and the slipper torque, which decreases the pressing force between the input-side rotating plate 20 and the output-side rotating plate 22, but it may be necessary to increase the other. In that case, if the areas of the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S are equal, the area of ​​either the pressure-side assist cam surface 90A or the pressure-side slipper cam surface 90S will be larger than the required area. However, according to this embodiment, it is not necessary to make the areas of the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S equal, so their areas can be set appropriately. That is, the area of ​​the pressure-side assist cam surface 90A can be set to an area corresponding to the assist torque, and the area of ​​the pressure-side slipper cam surface 90S can be set to an area corresponding to the slipper torque. As a result, the pressure plate 70, and consequently the clutch device 10, can be made compact, while suppressing the increase in the force applied per unit area of ​​the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S.

[0095] In the clutch device 10 of this embodiment, the area of ​​the pressure-side assist cam surface 90A is larger than the area of ​​the pressure-side slipper cam surface 90S. Here, as shown in Figure 1, when the pressure plate 70 holds more output-side rotating plates 22 than are held by the clutch center 40, a large portion of the rotational driving force of the input shaft is applied to the pressure-side assist cam surface 90A. That is, a large torque is applied to the pressure-side assist cam surface 90A. For this reason, it is desirable to increase the area of ​​the pressure-side assist cam surface 90A so that the surface pressure received by the pressure-side assist cam surface 90A is appropriate. However, if the area of ​​the pressure-side slipper cam surface 90S (see Figure 12) is also made equal to the area of ​​the pressure-side assist cam surface 90A, the pressure-side slipper cam surface 90S will become unnecessarily large, which may lead to an increase in the size of the clutch device 10. However, according to this embodiment, since the area of ​​the pressure-side assist cam surface 90A is larger than the area of ​​the pressure-side slipper cam surface 90S, even when the pressure plate 70 holds more output-side rotating plates 22 than the clutch center 40 holds, the clutch device 10 can be compact while still providing an appropriate surface pressure on the pressure-side assist cam surface 90A.

[0096] According to the clutch device 10 of this embodiment, as shown in Figure 12, the axial length L10 of the pressure-side assist cam surface 90A is longer than the axial length L11 of the pressure-side slipper cam surface 90S. The inclined length L12 of the pressure-side assist cam surface 90A is longer than the inclined length L19 of the pressure-side slipper cam surface 90S. According to this embodiment, with a simple configuration, the area of ​​the pressure-side assist cam surface 90A can be made larger than the area of ​​the pressure-side slipper cam surface 90S.

[0097] In the clutch device 10 of this embodiment, the end 95 of the pressure-side assist cam surface 90A on the second direction D2 side is located further towards the second direction D2 than the end 96 of the pressure-side slipper cam surface 90S on the second direction D2 side. As shown in Figure 7, the pressure-side cam portion 90 protrudes in the first direction D1. Here, as a method to make the area of ​​the pressure-side assist cam surface 90A larger than the area of ​​the pressure-side slipper cam surface 90S, it is conceivable to extend the pressure-side assist cam surface 90A towards the first direction D1 side. However, this would move the clutch center 40 towards the first direction D1 side, thus increasing the size of the clutch device 10 in direction D. On the other hand, in this embodiment, as shown in Figure 12, the end 95 of the pressure-side assist cam surface 90A on the second direction D2 side is located further towards the second direction D2 than the end 96 of the pressure-side slipper cam surface 90S on the second direction D2 side. The pressure-side assist cam surface 90A is extended toward the second direction D2. Therefore, compared to the case where the pressure-side assist cam surface 90A is extended toward the first direction D1, the protrusion of the pressure plate 70 toward the first direction D1 can be suppressed. As a result, there is no need to move the clutch center 40 toward the first direction D1, and the clutch device 10 can be made more compact.

[0098] In the clutch device 10 of this embodiment, the end 95 of the pressure-side assist cam surface 90A is connected to the end surface 90D (see Figure 8) of the pressure-side cam portion 90 on the second direction D2 side. The end 95 of the pressure-side assist cam surface 90A is the end of the pressure-side cam portion 90 in the second direction D2. Therefore, it is possible to suppress the extension of the pressure plate 70 toward the first direction D1 and to further increase the area of ​​the pressure-side assist cam surface 90A. As a result, the area of ​​the pressure-side assist cam surface 90A can be further increased and the clutch device 10 can be made more compact.

[0099] In the clutch device 10 of this embodiment, as shown in Figure 1, the pressure plate 70 holds all of the output-side rotating plates 22. Here, when the number of output-side rotating plates 22 held by the pressure plate 70 is relatively large, the force applied to the pressure-side assist cam surface 90A via the output-side rotating plates 22 becomes relatively large. However, in this embodiment, the force applied per unit area of ​​the pressure-side assist cam surface 90A is suppressed, so even when the number of output-side rotating plates 22 held by the pressure plate 70 is relatively large, the durability of the pressure plate 70 and the clutch center 40 can be improved. When the pressure plate 70 holds all of the output-side rotating plates 22, the force applied to the pressure-side assist cam surface 90A is particularly large. Therefore, it is especially preferable to apply the technology disclosed herein.

[0100] In the clutch device 10 of this embodiment, as shown in Figure 6, the area of ​​the center-side assist cam surface 60A and the area of ​​the center-side slipper cam surface 60S are different from each other. Here, the length L3 in direction D of the center-side assist cam surface 60A and the length L4 in direction D of the center-side slipper cam surface 60S are different from each other. Also, the length L5 in the inclined surface direction of the center-side assist cam surface 60A and the length L6 in the inclined surface direction of the center-side slipper cam surface 60S are different from each other. In this embodiment, it is not necessary to make the area of ​​the center-side assist cam surface 60A and the area of ​​the center-side slipper cam surface 60S equal, so their areas can be set appropriately. In this embodiment, the area of ​​the center-side assist cam surface 60A can be set to an area corresponding to the assist torque, and the area of ​​the center-side slipper cam surface 60S can be set to an area corresponding to the slipper torque. This makes it possible to maintain a compact clutch center 40 and, consequently, the clutch device 10, while suppressing an increase in the force applied per unit area of ​​the center-side assist cam surface 60A and the center-side slipper cam surface 60S.

[0101] In the clutch device 10 of this embodiment, the area of ​​the center-side assist cam surface 60A is larger than the area of ​​the center-side slipper cam surface 60S. Here, as shown in Figure 17, when the pressure plate 70 holds more output-side rotating plates 22 than are held by the clutch center 40, a large portion of the rotational driving force of the input shaft is applied to the center-side assist cam surface 60A. That is, a large torque is applied to the center-side assist cam surface 60A. For this reason, it is desirable to increase the area of ​​the center-side assist cam surface 60A so that the surface pressure received by the center-side assist cam surface 60A is appropriate. However, if the area of ​​the center-side slipper cam surface 60S is also made equal to the area of ​​the center-side assist cam surface 60A, the center-side slipper cam surface 60S will become unnecessarily large, which may lead to an increase in the size of the clutch device 10. However, according to this embodiment, since the area of ​​the center-side assist cam surface 60A is larger than the area of ​​the center-side slipper cam surface 60S, even when the pressure plate 70 holds more output-side rotating plates 22 than the clutch center 40 holds, the clutch device 10 can be compact while still providing an appropriate surface pressure on the center-side assist cam surface 60A.

[0102] In the clutch device 10 of this embodiment, the axial length L3 of the center-side assist cam surface 60A is longer than the axial length L4 of the center-side slipper cam surface 60S. As shown in Figure 4, the radial length L1 of the center-side assist cam surface 60A is longer than the radial length L2 of the center-side slipper cam surface 60S. As shown in Figure 6, the inclined length L5 of the center-side assist cam surface 60A is longer than the inclined length L6 of the center-side slipper cam surface 60S. According to this embodiment, with a simple configuration, the area of ​​the center-side assist cam surface 60A can be made larger than the area of ​​the center-side slipper cam surface 60S.

[0103] In the clutch device 10 of this embodiment, the end 67A of the center assist cam surface 60A on the second direction D2 side is located on the second direction D2 side than the end 67S of the center slipper cam surface 60S on the second direction D2 side. Here, the axial length L3 of the center assist cam surface 60A is longer than the axial length L4 of the center slipper cam surface 60S. If the axial length L3 of the center assist cam surface 60A is longer than the axial length L4 of the center slipper cam surface 60S, and the end 67A of the center assist cam surface 60A on the second direction is located on the first direction D1 side than the end 67S of the center slipper cam surface 60S on the second direction D2 side, then it is necessary to move the center slipper cam surface 60S to the second direction D2 side. Therefore, it is necessary to extend the slipper-side cam portion 63S of the center-side cam portion 60 toward the second direction D2. However, according to this embodiment, the end 67A of the center-side assist cam surface 60A toward the second direction D2 is located toward the second direction D2 than the end 67S of the center-side slipper cam surface 60S toward the second direction D2, so that the extension of the center-side cam portion 60 toward the second direction D2 can be suppressed. As a result, the extension of the clutch center 40 toward the second direction D2 is suppressed, and the clutch device 10 can be made more compact.

[0104] In the clutch device 10 of this embodiment, as shown in Figure 3, the assist-side cam portion 63A extends further in the second direction D2 than the slipper-side cam portion 63S. Therefore, while the area of ​​the center-side assist cam surface 60A is made larger than the area of ​​the center-side slipper cam surface 60S, the extension of the slipper-side cam portion 63S toward the second direction D2 is suppressed. Consequently, only the assist-side cam portion 63A, which is relatively close to the center-side assist cam surface 60A, can be extended toward the second direction D2. The slipper-side cam portion 63S, which is relatively close to the center-side slipper cam surface 60S, is suppressed from extending toward the second direction D2. As a result, the area of ​​the center-side assist cam surface 60A can be increased, and the center-side cam portion 60, and consequently the clutch device 10, can be made more compact.

[0105] In the clutch device 10 of this embodiment, as shown in Figure 5, the opening 54E on the first direction D1 side of the boss portion 54 is provided on the end face 63F of the assist-side cam portion 63A. Therefore, at least a part of the boss portion 54 is provided on the end face 63F of the assist-side cam portion 63A. The boss portion 54 extends toward the pressure plate 70 (see Figure 1), and therefore extends toward the second direction D2 as shown in Figure 3. Of the assist-side cam portion 63A and slipper-side cam portion 63S of the center-side main body portion 63, at least a part of the boss portion 54 is provided on the assist-side cam portion 63A, which extends further toward the second direction D2. This makes it possible to increase the overlapping range of the center-side cam portion 60 and the boss portion 54 in direction D. In other words, it makes it possible to increase the range in which the center-side cam portion 60 and the boss portion 54 can be integrated. Therefore, the clutch center 40, and by extension the clutch device 10, can be made more compact.

[0106] In the clutch device 10 of this embodiment, a part of the boss portion 54 is provided on the assist-side cam portion 63A. The assist-side cam portion 63A extends further toward the second direction D2 than the slipper-side cam portion 63S. When the assist torque is greater than the slipper torque, extending the assist-side cam portion 63A further toward the second direction D2 than the slipper-side cam portion 63S makes the area of ​​the center-side assist cam surface 60A larger than the area of ​​the center-side slipper cam surface 60S, thereby suppressing an increase in the force applied per unit area of ​​the center-side assist cam surface 60A. Therefore, an increase in the force applied per unit area of ​​the center-side assist cam surface 60A is suppressed, and the clutch center 40, and consequently the clutch device 10, can be made more compact.

[0107] In the clutch device 10 of this embodiment, the boss portion 54 is formed spanning the assist-side cam portion 63A and the slipper-side cam portion 63S. A part of the boss portion 54 is integrally formed with the assist-side cam portion 63A, and another part is integrally formed with the slipper-side cam portion. Here, since the boss portion 54 is provided on the center-side cam portion 60, when assist torque is generated and when slipper torque is generated, force is applied to the boss portion 54 via the center-side assist cam surface 60A or the center-side slipper cam surface 60S. Because the boss portion 54 is arranged spanning the assist-side cam portion 63A and the slipper-side cam portion 63S, the force applied to the boss portion 54 can be reduced compared to the case where the boss portion 54 is biased towards either the center-side assist cam surface 60A or the center-side slipper cam surface 60S.

[0108] In the clutch device 10 of this embodiment, as shown in Figure 4, the assist-side cam portion 63A has an assist-side recess 65 that is recessed in the first direction D1. This allows the weight of the assist-side cam portion 63A to be kept relatively small, even when the assist-side cam portion 63A extends relatively long in the second direction D2. Therefore, the clutch center 40, and consequently the clutch device 10, can be made lighter. In this embodiment, as shown in Figure 6, the bottom surface 65E of the assist-side recess 65 on the first direction D1 side is located on the first direction D1 side than the end surface 63G of the slipper-side cam portion 63S in the second direction. Therefore, the length of the assist-side recess 65 in direction D is relatively long. This allows for further weight reduction of the clutch center 40, and consequently the clutch device 10.

[0109] In the clutch device 10 of this embodiment, as shown in Figure 3, the assist-side recess 65 is formed in the assist-side cam portion 63A. By extending the assist-side cam portion 63A toward the second direction D2 side more than the slipper-side cam portion 63S, the area of ​​the center-side assist cam surface 60A can be made larger than the area of ​​the center-side slipper cam surface 60S. This makes it possible to suppress an increase in the force applied per unit area of ​​the center-side assist cam surface 60A. Therefore, by forming the assist-side recess 65 in the assist-side cam portion 63A, it is possible to suppress an increase in the force applied per unit area of ​​the center-side assist cam surface 60A, and to reduce the weight of the clutch center 40 and, consequently, the clutch device 10.

[0110] In the clutch device 10 of this embodiment, as shown in Figure 5, the slipper-side cam portion 63S has a slipper-side recess 66 that is recessed in the second direction D2. This makes it possible to reduce the weight of the slipper-side cam portion 63S relatively. Therefore, the clutch center 40 and, consequently, the clutch device 10 can be made lighter.

[0111] In the clutch device 10 of this embodiment, as shown in Figure 3, at least a portion of the assist-side cam portion 63A and at least a portion of the slipper-side cam portion 63S are integrated with the boss portion 43. Therefore, a relatively large portion of the center-side cam portion 60 is connected to the boss portion 43. The center-side cam portion 60 has a center-side assist cam surface 60A and a center-side slipper cam surface 60S formed thereon. As a result, force is applied to the center-side cam portion 60 when assist torque or slipper torque is generated. As in this embodiment, by connecting a relatively large portion of the center-side cam portion 60 to the boss portion 43, the strength of the clutch center 40 can be improved.

[0112] In the clutch device 10 of this embodiment, as shown in Figure 4, an inner circumferential recess 63R is formed between the main inner circumferential surface 63N and the boss portion 43. The inner circumferential recess 63R is formed to be recessed in the direction from the center-side slipper cam surface 60S toward the center-side assist cam surface 60A (here, the second circumferential direction S2). Here, the slipper torque may be smaller than the assist torque. When the strength of the clutch center 40 is improved by the connection between the main inner circumferential surface 63N and the boss portion 43, the strength of the clutch center 40 may have a relatively large margin against the force when the slipper torque is generated. In such cases, even if an inner circumferential recess 63R recessed toward the second circumferential direction S2 is formed at the part where the main inner circumferential surface 63N and the boss portion 43 are connected, it is possible to ensure the strength of the clutch center 40 against the force when the slipper torque is generated. On the other hand, the volume of the boss portion 43 is reduced because the inner circumferential recess 63R is recessed toward the second circumferential direction S2. Therefore, by forming an inner circumferential recess 63R that is recessed in the direction from the center slipper cam surface 60S toward the center assist cam surface 60A, the strength of the clutch center 40 can be ensured against the force when slipper torque is generated, while the weight of the clutch center 40 can be reduced.

[0113] In the embodiment described above, as shown in Figure 1, all of the multiple output-side rotating plates 22 were held by the pressure plate 70, but the invention is not limited to this. The present invention can also be applied to a clutch device in which the clutch center 40 and the pressure plate 70 each hold the output-side rotating plates 22. Figure 21 is a cross-sectional view of a clutch device 10A according to a first modification. The clutch device 10A includes a clutch center 40A.

[0114] The clutch center 40A has a ring-shaped center-side flange 68 and a center-side main body portion 42A located radially inward of the center-side flange 68. The center-side main body portion 42A includes an annular boss portion 43, a center-side cam portion 60, a center-side fitting portion 58, and an outer peripheral wall 45 connected to the center-side fitting portion 58.

[0115] The outer peripheral wall 45 is positioned radially outward from the boss portion 43. The outer peripheral wall 45 extends in a second direction D2 beyond the center side flange 68. The outer peripheral wall 45 has a plurality of center side fitting teeth 47 that project radially outward from the outer peripheral surface of the outer peripheral wall 45. The plurality of center side fitting teeth 47 are arranged in the circumferential direction S (see Figure 3). Here, the center side fitting teeth 47 hold one of the five output side rotating plates 22.

[0116] The pressure-side mating teeth 77 of the pressure plate 70 hold four of the five output-side rotating plates 22. However, the number of output-side rotating plates 22 held by the pressure plate 70 is not particularly limited, as long as it is greater than the number of output-side rotating plates 22 held by the clutch center 40A.

[0117] In the clutch device 10A according to the first modified example, the number of output-side rotating plates 22 held by the pressure plate 70 is greater than the number of output-side rotating plates 22 held by the clutch center 40A. Similar to the embodiment described above, the force applied per unit area of ​​the pressure-side assist cam surface 90A is suppressed, so even when the number of output-side rotating plates 22 held by the pressure plate 70 is relatively large, the durability of the pressure plate 70 and the clutch center 40A can be improved.

[0118] Figure 22 is a perspective view showing a pressure plate 370 according to a second modified example. As shown in Figure 22, the pressure plate 370 has three oil discharge holes 79L, 79M, and 79N1. Similar to the pressure plate 70 (see Figure 7), the oil discharge holes 79L, 79M, and 79N1 are each formed in one of the three aligned toothed portions 76. The oil discharge holes 79L, 79M, and 79N1 are arranged at approximately equal intervals in the circumferential direction S. The oil discharge holes 79L, 79M, and 79N1 are arranged at offset positions from each other in direction D.

[0119] In the second modified example, the pressure-side main body portion 72 of the pressure plate 370 has a through hole 389 instead of the through hole 89 (see Figure 8). The through hole 389 is formed in a substantially rectangular shape when viewed from direction D (see also Figure 23). A notch 387 is formed in the toothless portion 76 of the pressure plate 370. The notch 387 is a hole for discharging oil blocked by the pressure-side assist cam surface 90A to the outside of the pressure plate 70. As shown in Figure 23, the notch 387 is formed so as to be recessed from the end face 72D on the second direction D2 side of the pressure-side main body portion 72 toward the first direction D1. The notch 387 and the through hole 389 are in communication. The length of the notch 387 in the circumferential direction S is substantially the same as the length of the through hole 389 in the circumferential direction S. As shown in Figure 22, three notches 387 are formed along the circumferential direction S. The three notches 387 will also be referred to as notches 387L, 387M, and 387N. However, the name notch 387 will be used appropriately when it is common to all three notches 387L, 387M, and 387N. Notch 387L is formed in the toothed portion 76 in which the oil discharge hole 79L is formed, among the three toothed portions 76. Similarly, notches 387M and 387N are formed in the toothed portions 76 in which the oil discharge holes 79M and 79N1 are formed, among the three toothed portions 76. Notch 387 is located on the second direction D2 side of the oil discharge hole 79. As shown in Figure 24, the edge 387A of notch 387 on the first direction D1 side is located on the first direction D1 side of the end 95 of the pressure-side assist cam surface 90A on the second direction D2 side. The notch 387 is located close to the pressure-side assist cam surface 90A on the first circumferential direction S1 (the rotational direction of the pressure plate 370). For example, as shown in Figure 22, the distance in the circumferential direction S between the pressure-side assist cam surface 90A, which is located on the second circumferential direction S2 side of the notch 387L, and the notch 387L is shorter than the distance in the circumferential direction S between the pressure-side slipper cam surface 90S, which is located on the first circumferential direction S1 side of the notch 387L, and the notch 387L. The same applies to the distances between the notches 387M and 387N and the pressure-side assist cam surface 90A.

[0120] As shown in Figure 24, the circumferential distance S between the notch 387 and the pressure-side assist cam surface 90A is approximately the same as the circumferential distance S between the oil discharge hole 79 and the pressure-side assist cam surface 90A. Here, the pressure-side assist cam surface 90A extends toward the first circumferential direction S1 as it moves toward the first direction D1, and is inclined with respect to the axial direction. For this reason, for example, the notch 387N is shifted toward the second circumferential direction S2, in the direction toward the oil discharge hole 79N1 where the pressure-side assist cam surface 90A is inclined. In this case, the distance between the notch 387N and the pressure-side assist cam surface 90A is approximately the same as the distance between the oil discharge hole 79N1 and the pressure-side assist cam surface 90A. The same applies to the oil discharge hole 79L and notch 387L shown in Figure 22, and the oil discharge hole 79L and notch 387M. In addition, with respect to the circumferential direction S, the oil discharge hole 79 and the notch 387 may be provided at the same position.

[0121] Here, for example, when the engine speed increases and the pressure plate 370 rotates in the first circumferential direction S1, oil flows out from the output shaft 15 (see Figure 1) into the pressure plate 370. At this time, the oil flows in the opposite direction to the rotation direction S1, i.e., in the rotation direction S2, and a portion of the oil is blocked by the pressure-side assist cam surface 90A. The oil blocked by the pressure-side assist cam surface 90A flows along the pressure-side assist cam surface 90A in the second direction D2. According to the above embodiment, the oil blocked by the pressure-side assist cam surface 90A is discharged to the outside of the pressure plate 70 through the notch 387. Furthermore, according to the above embodiment, as shown in Figure 24, since the edge 387A of the notch 387 is located on the first direction D1 side than the end 95 of the pressure-side assist cam surface 90A, the oil blocked by the pressure-side assist cam surface 90A can be discharged to the outside of the pressure plate 70 more reliably. Moreover, since the circumferential distance S between the oil discharge hole 79 and the pressure-side assist cam surface 90A and the circumferential distance S between the notch 387 and the pressure-side assist cam surface 90A are substantially the same, the oil blocked by the pressure-side assist cam surface 90A can be reliably discharged to the outside of the pressure plate 70 by the oil discharge hole 79 and the notch 387.

[0122] The number of notches 387 is not particularly limited. For example, two or more notches 387 may be formed in one toothed portion 76 (see Figure 22). Also, the shape of the notches 387 is not limited to the second modified example described above. In the second modified example, the notches 387 were located on the second direction D2 side of the oil discharge hole 79, but for example, the notches 387 may extend to the first direction D1 side of the oil discharge hole 79.

[0123] <Second Embodiment> Figure 25 is a perspective view of the clutch center 140 according to the second embodiment. The clutch center 140 is housed in the clutch housing 30 (see Figure 1). The clutch center 140 is arranged concentrically with the clutch housing 30. As shown in Figure 25, the clutch center 140 has a center-side main body portion 142, a center-side recess 59, and a center-side flange 68. The center-side main body portion 142 includes an annular boss portion 143, an output shaft holding portion 50 provided in the center of the boss portion 143, a plurality of center-side cam portions 160 connected to the boss portion 143, and a housing portion recess 145. Three center-side cam portions 160 are arranged at equal intervals in the circumferential direction of the clutch center 140.

[0124] The center cam portion 160 is located radially outward from the output shaft holding portion 50. The center cam portion 160 has a center assist cam surface 160A and a center slipper cam surface 160S. A boss portion 54 is erected on the center cam portion 160.

[0125] The center cam portion 160 is provided with a protrusion 164. The protrusion 164 is formed on the radially inner portion of the center cam portion 160. The protrusion 164 is formed on the first circumferential direction S1 side and the second circumferential direction S2 side of the center cam portion 160, respectively. The protrusion 164 formed on the first circumferential direction S1 side will also be referred to as the first protrusion 164A, and the protrusion 164 formed on the second circumferential direction S2 side will also be referred to as the second protrusion 164B. The first protrusion 164A extends to the first circumferential direction S1 side. In the circumferential direction S, the first protrusion 164A extends to approximately the same position as the position on the center slipper cam surface 160S closest to the first circumferential direction S1. The second protrusion 164B, provided on the second circumferential direction S2 side, extends to the second circumferential direction S2 side. The second protrusion 164B extends in the circumferential direction S to approximately the same position as the second circumferential direction S2 side position of the center-side assist cam surface 160A. By providing the protrusion 164 on the center-side cam portion 160, the durability of the center-side cam portion 160 can be improved when the center-side assist cam surface 160A and the pressure-side assist cam surface 190A (see Figure 27), which will be described later, are in contact with each other and act together.

[0126] A stepped portion 165 is formed between the main inner surface 163A, which is the inner surface of the center cam portion 160, and the boss portion 143. The stepped portion 165 extends in the circumferential direction S. The stepped portion 165 is formed from the first end of the first convex portion 164A on the first circumferential direction S1 side to the second end of the second convex portion 164B on the second circumferential direction S2 side.

[0127] The housing recess 145 is formed between adjacent center-side cam portions 160 with respect to the circumferential direction S. The housing recess 145 is the portion into which the spring housing portion 184 (see Figure 27) of the pressure plate 170 (see Figure 27), which will be described later, is inserted. The housing recess 145 has a wall surface 146 and a bottom surface 147. The housing recess 145 may penetrate in direction D. The wall surface 146 is connected to the second protrusion 164B of one center-side cam portion 160L, the first protrusion 164A of the other center-side cam portion 160M, and the boss portion 143. The wall surface 146 is formed in a substantially C shape in plan view. The bottom surface 147 is the surface connected to the first direction D1 side of the wall surface 146. The wall surface 146 is located on the first direction D1 side of the end 158D of the center-side fitting portion 158 on the second direction D2 side. Parts of the wall surface 146 and the bottom surface 147 on the first circumferential direction S1 side are connected to the center-side cam hole 143H. When the spring housing portion 184 is inserted into the housing portion recess 145, there may be a gap between the wall surface 146 and the wall surface 185 of the spring housing portion 184 (described later), or there may be no gap (i.e., the wall surface 146 and the wall surface 185 may be fitted together).

[0128] As shown in Figure 26, a cam-side recess 166 is formed on the end face 160D of the center-side cam portion 160 on the first direction D1 side. The cam-side recess 166 is formed to recess toward the second direction D2 side. The cam-side recess 166 is formed on the center-side cam portion 160 toward the first circumferential direction S1 side than the boss portion 54. The cam-side recess 166 is formed in a substantially fan shape in plan view. The cam-side recess 166 is connected to the boss portion 143 on the radially inward side. The cam-side recess 166 is connected to the center-side cam hole 143H on the first circumferential direction S1 side. The formation of the cam-side recess 166 makes it possible to reduce the weight of the clutch center 140.

[0129] As shown in Figures 25 and 26, the clutch center 140 has a center-side cam hole 143H that penetrates a portion of the center-side main body portion 142. The center-side cam hole 143H extends from the boss portion 143 to the radially outward side of the center-side fitting portion 158. The center-side cam hole 143H is formed adjacent to the center-side assist cam surface 160A on the second circumferential direction S2 side. Viewed from direction D, a portion of the center-side assist cam surface 160A is located inside the center-side cam hole 143H.

[0130] Figure 27 is a perspective view of a pressure plate 170 according to a second embodiment. The pressure plate 170 is provided so as to be able to approach and move away from the clutch center 140 and to be able to rotate relative to it. The pressure plate 170 shown in Figure 27 is configured to be able to press the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 1). The pressure plate 170 is arranged concentrically with the clutch center 140 (see Figure 26) and the clutch housing 30 (see Figure 1). As shown in Figure 27, the pressure plate 170 comprises a pressure side body portion 172 and a pressure side flange 98. The pressure side body portion 172 protrudes from the pressure side flange 98 in a first direction D1. The pressure plate 70 holds a plurality of output side rotating plates 22 that are arranged alternately with the input side rotating plate 20.

[0131] The pressure-side main body portion 172 comprises a cylindrical portion 80, an outer peripheral wall 173, a plurality of pressure-side cam portions 190, a pressure-side fitting portion 88, and a spring housing portion 184.

[0132] The outer peripheral wall 173 is positioned radially outward from the cylindrical portion 80. The outer peripheral wall 173 extends in a first direction D1. The outer peripheral wall 173 has an annular wall 174A and a spline fitting portion 174B provided radially outward from the annular wall 174A. The spline fitting portion 174B has a plurality of pressure-side fitting teeth 177 extending in direction D and a plurality of spline grooves 178 formed between adjacent pressure-side fitting teeth 177. The pressure-side fitting teeth 177 hold the output-side rotating plate 22. The plurality of pressure-side fitting teeth 177 are aligned in the circumferential direction S. The plurality of pressure-side fitting teeth 177 are formed in the same shape. The pressure-side fitting teeth 77 protrude radially outward from the annular wall 174A.

[0133] The pressure-side cam portion 190 shown in Figure 27 is formed in a trapezoidal shape having cam surfaces 190A and 190S which are inclined surfaces. The pressure-side cam portion 190 is formed to protrude in the first direction D1 from the pressure-side flange 98. The pressure-side cam portions 190 are arranged at equal intervals in the circumferential direction S of the pressure plate 170. In this embodiment, the pressure plate 170 has three pressure-side cam portions 190, but the number of pressure-side cam portions 90 is not limited to three.

[0134] The pressure-side cam portion 190 is located radially outward from the cylindrical portion 80. The pressure-side cam portion 190 includes a pressure-side assist cam portion 191 including a pressure-side assist cam surface 190A, a pressure-side slipper cam portion 192 including a pressure-side slipper cam surface 190S, and a pressure-side cam body portion 193 located between the pressure-side assist cam portion 191 and the pressure-side slipper cam portion 192. The pressure-side assist cam portion 191, the pressure-side cam body portion 193, and the pressure-side slipper cam portion 192 are integrally formed.

[0135] As shown in Figure 28, the pressure-side cam portion 190 is connected to the pressure-side cam hole 173H, which will be described later, at its end on the second circumferential direction S2 side. As shown in Figure 27, the pressure-side cam portion 190 and the pressure-side cam hole 173H are connected on the second direction D2 side of the pressure-side slipper cam surface 190S.

[0136] The pressure plate 170 has a pressure-side cam hole 173H that penetrates a portion of the pressure-side main body portion 172 in direction D. The pressure-side cam hole 173H is located radially outward from the cylindrical portion 80. The pressure-side cam hole 173H is formed between the pressure-side assist cam surface 190A and the pressure-side slipper cam surface 190S of the adjacent pressure-side cam portion 190. As shown in Figure 28, when viewed from direction D, a portion of the pressure-side assist cam surface 190A is located inside the pressure-side cam hole 173H.

[0137] The pressure-side cam hole 173H has a cam hole recess 174. The cam hole recess 174 is formed on the first circumferential direction S1 side of the pressure-side cam hole 173H. The cam hole recess 174 is a recessed portion of the pressure-side cam hole 173H on the first circumferential direction S1 side. The cam hole recess 174 is connected to the pressure-side cam portion 190. The radial length of the cam hole recess 174 is formed to be approximately the same as the radial length of the pressure-side cam portion 190. When the pressure plate 170 and the clutch center 140 are assembled, the boss portion 54 (see Figure 25) is inserted into the area inside the cam hole recess 174. Therefore, the cam hole recess 174 prevents the boss portion 54 from interfering with the pressure plate 170.

[0138] As shown in Figure 28, the spring housing portion 184 is formed on the end face 190D of the pressure-side cam portion 190 on the second direction D2 side. The spring housing portion 184 is formed to be recessed from the end face 190D of the pressure-side cam portion 190 toward the first direction D1 side. When viewed from direction D, the spring housing portion 184 is formed in a substantially circular shape. The spring housing portion 184 is the part that houses the clutch spring 25 (see Figure 1).

[0139] As shown in Figure 27, the spring housing portion 184 has a wall surface 185 and a bottom surface 186. The wall surface 185 is a wall surface that surrounds the clutch spring 25 (see Figure 1) in the circumferential direction. The wall surface 185 extends from the end surface 190E on the first direction D1 side of the pressure-side cam portion 190 to the first direction D1. The wall surface 185 is also connected to the cylindrical portion 80 on the radially inner side. The bottom surface 186 is connected to the end of the wall surface 185 on the first direction D1 side. The bottom surface 186 is formed in a circular shape in plan view. When the pressure plate 170 is assembled to the clutch center 140 (see Figure 25), the portion of the spring housing portion 184 on the first direction D1 side of the pressure-side cam portion 190 is inserted into the housing recess 145 (see Figure 25) of the clutch center 140. Furthermore, at this time, the bottom surface 186 of the spring housing portion 184 is positioned to face the bottom surface 147 (see Figure 25) of the housing portion recess 145. By inserting the spring housing portion 184 into the housing portion recess 145 of the clutch center 140, the dimensions of the clutch device 10 in direction D can be made more compact.

[0140] <Third Embodiment> Figure 29 is a cross-sectional view of the clutch device 210 according to the third embodiment. As shown in Figure 29, the clutch device 210 includes an output shaft 15, an input side rotating plate 20, an output side rotating plate 22, a clutch housing 30, a clutch center 240, a pressure plate 270, a clutch spring 25, and a lifter plate 300. The clutch device 210 is a so-called external-cutting type clutch device in which the pressure plate 270 is located between the clutch center 240 and the clutch housing 230.

[0141] As shown in Figure 29, the clutch housing 30 supports the input side rotating plate 20. The pressure plate 270 supports all of the output side rotating plates 22. When the rotational axes of the clutch housing 30 and the output side rotating plates 22 are located coaxially (i.e., on axis CL), as shown in Figure 30, the radial distance between the inner circumferential surface 33N of the side wall 33 of the clutch housing 30 and the outer circumferential edge 22U of the output side rotating plate 22 is length L23. As shown in Figure 29, the clutch spring 25 is in contact with the clutch center 240. The clutch center 240 has a spring housing portion formed to be recessed, for example, from a first direction D1 to a second direction D2. The clutch spring 25 is housed in this spring housing portion.

[0142] The lifter plate 300 is a component for displacing the pressure plate 270 in direction D. The lifter plate 300 is fixed to the pressure plate 270. The lifter plate 300 is fixed to a boss portion 254 formed on the pressure plate 270 by bolts 28. The lifter plate 300 rotates integrally with the pressure plate 270. The lifter plate 300 moves in direction D relative to the clutch center 240 and rotates relative to the clutch center 240. The lifter plate 300 is formed in a disc shape. Although not shown in the figures, the lifter plate 300 is provided with, for example, a release bearing. The release bearing is a component that is pressed by the release fork of a clutch release mechanism (not shown). Here, the clutch release mechanism is a mechanical device in a vehicle such as a motorcycle equipped with a clutch device 210 that presses the release bearing toward the output shaft 15 side (i.e., the second direction D2 side) via a release fork when the driver operates the clutch operation lever (not shown). The lifter plate 300 supports the clutch spring 25. The lifter plate 300 has insertion holes 304H into which bolts 28 that fix the lifter plate 300 to the pressure plate 270 are inserted.

[0143] The pressure plate 270 is provided by the lifter plate 300 so as to be able to move toward and away from the clutch center 240 and to rotate relative to it. The pressure plate 270 has a pressure-side body portion 72, similar to the pressure plate 70 (see Figure 7) according to the first embodiment. The pressure-side body portion 72 has a projection 75 and pressure-side fitting teeth 77, similar to the first embodiment. The projection 75 is formed in a shape in which its radial length decreases as it moves toward the first direction D1. An inclined surface 75S1 is formed on the outer circumferential surface of the projection 75, extending radially inward toward the end face 75A of the projection 75 on the first direction D1 side. As shown in Figure 30, when the rotational axes of the clutch housing 30, the output rotating plate 22, and the pressure plate 270 are located coaxially (i.e., on axis CL (see Figure 29)), the radial distance between the edge 75E on the first direction D1 side of the inclined surface 75S1 and the inner peripheral edge 22N of the output rotating plate 22 is length L24. Length L24 is longer than the radial distance L23 between the inner peripheral surface 33N of the side wall 33 and the outer peripheral edge 22U of the output rotating plate 22. The radial distance between the outer peripheral surface 77U of the pressure-side fitting teeth 77 and the inner peripheral edge 22N of the output rotating plate 22 is length L25. Length L25 is shorter than length L23. In the clutch device 210 according to the third embodiment, as with the clutch device 10 according to the first embodiment (see Figure 1), when the pressure plate 270 is not assembled to the clutch center 240, the output-side rotating plate 22 falls due to its own weight and is supported by the inner circumferential surface 33N of the clutch housing 30. When the output-side rotating plate 22 is supported by the inner circumferential surface 33N, the edge 75E of the inclined surface 75S1 can be located radially inward from the inner circumferential edge 22N of the output-side rotating plate 22. Therefore, in the clutch device 210 according to the third embodiment, as with the clutch device 10 according to the first embodiment (see Figure 1), the radial positioning of the output-side rotating plate 22 can be suitably achieved. Furthermore, when the output-side rotating plate 22 is pushed up by the protrusion 75, contact between the output-side rotating plate 22 and the inner circumferential surface 33N of the side wall 33 is prevented.Therefore, in the clutch device 210 according to the third embodiment, similar to the clutch device 10 according to the first embodiment, the pressure-side fitting teeth 77 can be easily inserted into the inner diameter side of the input-side rotating plate 20 and the output-side rotating plate 22. This allows the pressure plate 270 to be assembled to the clutch center 240 more smoothly.

[0144] Preferred embodiments of the present invention have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms.

[0145] In the embodiments described above, only the pressure plate held the output-side rotating plate 22, but this is not limited to this. The clutch center may hold a portion of the output-side rotating plate 22. The clutch center may hold more of the output-side rotating plate 22 than the pressure plate, and the length of the pressure-side assist cam surface in the inclined surface direction may be different from the length of the pressure-side slipper cam surface in the inclined surface direction.

[0146] 10 Clutch device 15 Output shaft 20 Input side rotating plate 22 Output side rotating plate 25 Clutch spring 30 Housing 40 Clutch center 43H Center side cam hole 50 Output shaft holding part 58 Center side fitting part 60 Center side cam part 60A Center side assist cam surface 60S Center side slipper cam surface 70 Pressure plate 73 Outer peripheral wall 74 Cylindrical part 74D End face 84 Spring housing part 88 Pressure side fitting part 90 Pressure side cam part 90A Pressure side assist cam surface 90S Pressure side slipper cam surface 100 Stopper plate D1 First direction D2 Second direction

Claims

1. A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that rotates upon receiving the rotational driving force and holds a plurality of input-side rotating plates arranged in an axial direction which is the direction of the axis of the output shaft, and which rotates together with the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the axial direction; and a pressure plate provided so as to be able to approach and move away from the clutch center in the axial direction and to be rotatable relative to the clutch center, and which holds one or more of the plurality of output-side rotating plates and presses the input-side rotating plates and the output-side rotating plates, wherein the clutch center does not hold the plurality of output-side rotating plates, or holds one or more of the plurality of output-side rotating plates, and the pressure plate has a plurality of pressure-side cam portions having a pressure-side assist cam surface and a pressure-side slipper cam surface, and holds more of the output-side rotating plates than the number of output-side rotating plates held by the clutch center. A clutch device wherein the pressure-side assist cam surface is configured to increase the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force in the direction that moves the pressure plate closer to the clutch center when the pressure plate rotates relative to the clutch center, and the pressure-side slipper cam surface is configured to decrease the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force in the direction that moves the pressure plate away from the clutch center when the pressure plate rotates relative to the clutch center, and the area of ​​the pressure-side assist cam surface is larger than the area of ​​the pressure-side slipper cam surface.

2. The clutch device according to claim 1, wherein the axial length of the pressure-side assist cam surface is longer than the axial length of the pressure-side slipper cam surface.

3. The clutch device according to claim 2, wherein the length of the longest portion of the radial length of the output shaft of the pressure-side assist cam surface is longer than the length of the longest portion of the radial length of the pressure-side slipper cam surface.

4. The clutch device according to claim 2, wherein when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the end of the pressure-side assist cam surface in the second direction is located on the side of the second direction that is greater than the end of the pressure-side slipper cam surface in the second direction.

5. The clutch device according to claim 4, wherein the end of the pressure-side assist cam surface in the second direction is the end of the pressure-side cam portion in the second direction.

6. With respect to the circumferential direction of the output shaft, when the direction from one of the pressure-side cam portions toward the other pressure-side cam portion is defined as the first circumferential direction, and the direction from the other pressure-side cam portion toward the one pressure-side cam portion is defined as the second circumferential direction, the surface of the pressure-side cam portion toward the first direction is formed flat from the first circumferential end of the pressure-side assist cam surface toward the first circumferential end of the pressure-side slipper cam surface, as described in claim 4.

7. The clutch device according to claim 1, wherein the pressure-side assist cam surface and the pressure-side slipper cam surface are inclined with respect to the axis, and the length of the pressure-side assist cam surface in the inclined surface direction is longer than the length of the pressure-side slipper cam surface in the inclined surface direction.

8. The clutch device according to claim 1, wherein the clutch center holds one or more of the plurality of output-side rotating plates, the pressure plate holds all of the plurality of output-side rotating plates except for the output-side rotating plate held by the clutch center, and the number of output-side rotating plates held by the pressure plate is greater than the number of output-side rotating plates held by the clutch center.

9. The clutch device according to claim 1, wherein the pressure plate holds all of the plurality of output-side rotating plates.

10. The clutch device according to claim 1, wherein the area of ​​the pressure-side assist cam surface is 1.5 to 3 times the area of ​​the pressure-side slipper cam surface.

11. The clutch device according to claim 10, wherein the area of ​​the pressure-side assist cam surface is 1.5 to 2.5 times the area of ​​the pressure-side slipper cam surface.

12. The clutch device according to claim 1, wherein the radial length of the output shaft of the pressure-side assist cam surface is the same as the radial length of the pressure-side slipper cam surface.

13. The clutch device according to claim 12, wherein when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the radial length of the pressure-side assist cam surface at the end in the first direction is the same as the radial length of the pressure-side slipper cam surface at the end in the first direction.

14. The clutch device according to claim 12, wherein the midpoint of the radial direction of the pressure-side assist cam surface and the midpoint of the radial direction of the pressure-side slipper cam surface are located on the same circular arc centered on the axis when viewed in the axial direction.

15. The clutch device according to claim 14, wherein, when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the midpoint in the radial direction at the end of the pressure-side assist cam surface in the first direction and the midpoint in the radial direction at the end of the pressure-side slipper cam surface in the first direction are located on the same arc centered on the axis when viewed in the axial direction.

16. A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that rotates upon receiving the rotational driving force and holds a plurality of input-side rotating plates arranged in an axial direction which is the direction of the axis of the output shaft, and which rotates together with the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the axial direction; and a pressure plate provided so as to be able to approach and move away from the clutch center in the axial direction and to be rotatable relative to the clutch center, and which holds one or more of the plurality of output-side rotating plates and presses the input-side rotating plates and the output-side rotating plates, wherein the clutch center does not hold the plurality of output-side rotating plates, or holds one or more of the plurality of output-side rotating plates; the pressure plate holds more of the output-side rotating plates than the clutch center holds; and the clutch center has a plurality of center-side cam portions having a center-side assist cam surface and a center-side slipper cam surface. The center-side assist cam surface is configured to increase the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force in the direction that moves the pressure plate closer to the clutch center when the clutch center rotates relative to the pressure plate, and the center-side slipper cam surface is configured to decrease the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force in the direction that moves the pressure plate away from the clutch center when the clutch center rotates relative to the pressure plate, and the area of ​​the center-side assist cam surface is larger than the area of ​​the center-side slipper cam surface.

17. The clutch device according to claim 16, wherein the axial length of the center assist cam surface is longer than the axial length of the center slipper cam surface.

18. The clutch device according to claim 16, wherein the length of the longest portion of the radial length of the output shaft of the center assist cam surface is longer than the length of the longest portion of the radial length of the center slipper cam surface.

19. The clutch device according to claim 17, wherein when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the end of the center-side assist cam surface on the second direction side is located on the second direction side than the end of the center-side slipper cam surface on the second direction side.

20. The clutch device according to claim 16, wherein the center assist cam surface and the center slipper cam surface are inclined with respect to the axis, and the length of the center assist cam surface in the inclined surface direction is longer than the length of the center slipper cam surface in the inclined surface direction in the axial direction.

21. The clutch device according to claim 16, wherein the center-side cam portion comprises an assist-side cam portion having the center-side assist cam surface, and a slipper-side cam portion having the center-side slipper cam surface and aligned with respect to the assist-side cam portion along the circumferential direction of the output shaft, and when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the assist-side cam portion extends further in the second direction than the slipper-side cam portion.

22. The clutch device according to claim 21, wherein the pressure plate has a plurality of pressure-side cam portions having a pressure-side assist cam surface and a pressure-side slipper cam surface, the pressure-side assist cam surface is configured to increase the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force in the direction that moves the pressure plate closer to the clutch center when the pressure plate rotates relative to the clutch center, the pressure-side slipper cam surface is configured to decrease the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force in the direction that moves the pressure plate away from the clutch center when the pressure plate rotates relative to the clutch center, and the axial length of the pressure-side assist cam surface is longer than the axial length of the pressure-side slipper cam surface.

23. The clutch device according to claim 16, wherein, when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as a first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as a second direction, the clutch device further comprises a stopper plate fixed to the clutch center and in contact with the pressure plate to restrict the pressure plate from moving away from the clutch center by a predetermined distance or more in the second direction, the clutch center has a boss portion extending toward the pressure plate and having a screw hole formed therein for attaching the stopper plate, the center-side cam portion has a first cam portion having either the center-side assist cam surface or the center-side slipper cam surface, and a second cam portion having the other of the center-side assist cam surface or the center-side slipper cam surface, the first cam portion extends further in the second direction than the second cam portion, and at least a part of the boss portion is provided on the first cam portion.

24. The clutch device according to claim 23, wherein the first cam portion is an assist-side cam portion having the center-side assist cam surface, and the second cam portion is a slipper-side cam portion having the center-side slipper cam surface.

25. The clutch device according to claim 23, wherein the boss portion is provided spanning the first cam portion and the second cam portion.

26. The clutch device according to claim 16, wherein the center-side cam portion comprises a first cam portion having either the center-side assist cam surface or the center-side slipper cam surface, and a second cam portion having the other of the center-side assist cam surface or the center-side slipper cam surface, and when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the first cam portion extends further in the second direction than the second cam portion, and the first cam portion has a first recess that recesses from the end face in the second direction in the first direction.

27. The clutch device according to claim 26, wherein the first cam portion is an assist-side cam portion having the center-side assist cam surface, and the second cam portion has the center-side slipper cam surface.

28. The clutch device according to claim 26, wherein the bottom surface of the first recess in the first direction is located in the first direction more than the end surface of the second cam portion in the second direction.

29. The clutch device according to claim 16, wherein the center-side cam portion comprises a first cam portion having either the center-side assist cam surface or the center-side slipper cam surface, and a second cam portion having the other of the center-side assist cam surface or the center-side slipper cam surface, and when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the first cam portion extends further in the second direction than the second cam portion, and the second cam portion has a second recess that recesses from the end face in the first direction in the second direction.

30. The clutch device according to claim 16, wherein the clutch center covers the periphery of the output shaft and has a boss portion held by the output shaft, the center-side cam portion has a first cam portion having either the center-side assist cam surface or the center-side slipper cam surface, and a second cam portion having the other of the center-side assist cam surface or the center-side slipper cam surface, the first cam portion and the second cam portion are arranged radially outward from the boss portion of the output shaft, and at least a portion of the first cam portion and at least a portion of the second cam portion are connected to the boss portion.

31. The clutch device according to claim 30, wherein when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the first cam portion extends further in the second direction than the second cam portion, and the clutch center has an inner circumferential recess that is recessed in the direction from the center-side slipper cam surface toward the center-side assist cam surface along the circumferential direction of the output shaft, on the radially inner side of the first cam portion and the second cam portion, and on the radially outer side of the boss portion.

32. The clutch device according to claim 16, wherein the area of ​​the center assist cam surface is 1.5 to 3 times the area of ​​the center slipper cam surface.

33. The clutch device according to claim 32, wherein the area of ​​the center-side assist cam surface is 1.5 to 2.5 times the area of ​​the center-side slipper cam surface.

34. The clutch device according to claim 16, wherein the radial length of the output shaft of the center assist cam surface is the same as the radial length of the center slipper cam surface.

35. The clutch device according to claim 34, wherein when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the radial length of the center-side assist cam surface at the end in the second direction is the same as the radial length of the center-side slipper cam surface at the end in the second direction.

36. The clutch device according to claim 34, wherein the midpoint of the radial direction of the center assist cam surface and the midpoint of the radial direction of the center slipper cam surface are located on the same circular arc centered on the axis when viewed in the axial direction.

37. The clutch device according to claim 36, wherein, when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as the first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as the second direction, the midpoint in the radial direction at the end of the center-side assist cam surface in the second direction and the midpoint in the radial direction at the end of the center-side slipper cam surface in the second direction are located on the same arc centered on the axis when viewed in the axial direction.

38. A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that receives the rotational driving force and holds a plurality of input-side rotating plates arranged in an axial direction which is the direction of the axis of the output shaft, and rotates together with the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the axial direction; and a pressure plate provided so as to be able to approach and move away from the clutch center in the axial direction and to be rotatable relative to the clutch center, and holding one or more of the plurality of output-side rotating plates, and pressing the input-side rotating plates and the output-side rotating plates, wherein the pressure plate has a plurality of pressure-side cam portions having a pressure-side assist cam surface and a pressure-side slipper cam surface, and the pressure-side assist cam surface is configured to increase the pressing force between the input-side rotating plates and the output-side rotating plates by generating a force in a direction that brings the pressure plate closer to the clutch center when the pressure plate rotates relative to the clutch center. The clutch device is configured such that the pressure-side slipper cam surface generates a force that separates the pressure plate from the clutch center when the pressure plate rotates relative to the clutch center, thereby reducing the pressing force between the input-side rotating plate and the output-side rotating plate, the pressure-side assist cam surface and the pressure-side slipper cam surface are inclined with respect to the axis, and the length of the inclined surface direction of the pressure-side assist cam surface and the length of the inclined surface direction of the pressure-side slipper cam surface are different from each other.

39. The clutch device according to claim 38, wherein the length of the pressure-side assist cam surface in the inclined surface direction is longer than the length of the pressure-side slipper cam surface in the inclined surface direction.

40. The clutch device according to claim 38, wherein the pressure plate has a pressure-side pressing surface that presses against the output-side rotating plate, and when the direction in which the pressure plate approaches the clutch center along the axial direction is defined as a first direction, and the direction in which the pressure plate moves away from the clutch center along the axial direction is defined as a second direction, the end of the pressure-side assist cam surface in the second direction is located on the side of the pressure-side pressing surface in the second direction.

41. The clutch device according to claim 40, wherein the end of the pressure-side slipper cam surface in the second direction is located on the first direction side of the pressure-side pressing surface.

42. A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that receives the rotational driving force and holds a plurality of input-side rotating plates arranged in an axial direction which is the direction of the axis of the output shaft, and rotates together with the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the axial direction; and a pressure plate provided so as to be able to approach and move away from the clutch center in the axial direction and to be rotatable relative to the clutch center, and holding one or more of the plurality of output-side rotating plates, and pressing the input-side rotating plates and the output-side rotating plates, wherein the clutch center has a plurality of center-side cam portions having a center-side assist cam surface and a center-side slipper cam surface, and the center-side assist cam surface is configured to increase the pressing force between the input-side rotating plates and the output-side rotating plates by generating a force in a direction that brings the pressure plate closer to the clutch center when the clutch center rotates relative to the pressure plate. The center-side slipper cam surface is configured to reduce the pressing force between the input-side rotating plate and the output-side rotating plate by generating a force that separates the pressure plate from the clutch center when the clutch center rotates relative to the pressure plate, the center-side assist cam surface and the center-side slipper cam surface are inclined with respect to the axis, and the length of the inclined surface direction of the center-side assist cam surface and the length of the inclined surface direction of the center-side slipper cam surface are different from each other, in a clutch device.

43. The clutch device according to claim 42, wherein the length of the center assist cam surface in the inclined surface direction is longer than the length of the center slipper cam surface in the inclined surface direction in the axial direction.

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