Clutch device and motorcycle

Abstract

A clutch device (210) comprises a pressure plate (270) which is provided so as to be able to approach or separate from a clutch center (240) and to rotate relative thereto and which can press an input-side rotary plate (20) and an output-side rotary plate (22). The pressure plate (270) is configured to rotate in a first circumferential direction (S1). An oil drain hole (279) which is formed in a spline groove (278) so as to extend through the outer peripheral wall (275) of the pressure plate (270) and which drains clutch oil flowing out from an output shaft (15) to the outside of the pressure plate (270) is formed in a circumferential direction (S) between an end portion (90SB) of a pressure-side slipper cam surface (90S) in the first circumferential direction (S1) and a pressure-side cam hole (273H) located on a second circumferential direction (S2) side relative to the end portion (90SB) in the first circumferential direction (S1).

Description

[Technical field]

[0001] The present invention relates to a clutch device and a motorcycle, and more particularly to a clutch device that selectively transmits or cuts off the rotational driving force of an input shaft that is rotationally driven by a prime mover such as an engine to an output shaft, and a motorcycle equipped with the same. [Background technology]

[0002] Conventionally, vehicles such as motorcycles are equipped with a clutch device. The clutch device is disposed between an engine and a driving wheel, and transmits or interrupts the rotational driving force of the engine to the driving 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 driving wheel. The input side rotating plates and the output side rotating plates are arranged alternately in the stacking direction, and the transmission or interruption of the rotational driving force is performed by pressing the input side rotating plates and the output side rotating plates against each other and separating them.

[0003] For example, Patent Document 1 and Patent Document 2 disclose a clutch device including a clutch center and a pressure plate that is arranged so as to be able to approach and separate from the clutch center. The pressure plate is configured so as to be able to press an input side rotating plate and an output side rotating plate. In this way, the clutch device uses an assembled clutch center and pressure plate.

[0004] In the clutch device of Patent Document 1, the clutch center has center-side fitting teeth (an outer peripheral wall on which a spline is formed) and the pressure plate has pressure-side fitting teeth as portions for holding the output-side rotating plate. Meanwhile, in the clutch device of Patent Document 2, the pressure plate has pressure-side fitting teeth (an outer peripheral wall on which a spline is formed) as portions for holding the output-side rotating plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6903020 [Patent Document 2] International Publication No. 2018 / 172176 Summary of the Invention [Problem to be solved by the invention]

[0006] In the clutch device of Patent Document 2, clutch oil flowing out from the output shaft flows inside the pressure plate. A part of the clutch oil passes between the latch center and the pressure plate and flows to the outside of the pressure plate. Here, the input side rotating plate and the output side rotating plate held by the pressure side mating teeth are arranged outside the pressure plate. For this reason, it is desirable to efficiently flow the clutch oil from inside the pressure plate and supply it to the input side rotating plate and the output side rotating plate.

[0007] The present invention has been made in consideration of these points, and its object is to provide a clutch device that can efficiently discharge clutch oil from the inside of the pressure plate to the outside and supply clutch oil to the input side rotating plate and the output side rotating plate, and a motorcycle equipped with the same. [Means for solving the problem]

[0008] 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 includes: a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotating plates that are rotationally driven by the rotational driving of the input shaft and that rotates together with the output shaft; and a pressure plate that is arranged to be able to approach or move away from the clutch center and to be rotatable relative to the clutch center, holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plates, and is capable of pressing the input side rotating plates and the output side rotating plates, and the pressure plate is arranged to be able to press the input side rotating plates and the output side rotating plates against each other. a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the latch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; The clutch plate has an outer circumferential wall, a plurality of pressure side fitting teeth arranged in a circumferential direction and formed to hold the output side rotating plate and to protrude radially outward from an outer circumferential surface of the outer circumferential wall, a plurality of spline grooves formed between adjacent pressure side fitting teeth, and an oil discharge hole formed in the spline groove so as to penetrate the outer circumferential wall and capable of discharging clutch oil flowing on an inner circumferential side of the outer circumferential wall to the outside of the pressure plate, and the direction in which the pressure plate approaches the clutch center is defined as a first direction, and the direction in which the pressure plate moves away from the clutch center is defined as a second direction. a second direction, and a direction from one of the pressure-side cam portions to the other of the pressure-side cam portions in the circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure-side cam portions to one of the pressure-side cam portions is defined as a second circumferential direction. The pressure plate is configured to rotate in the first circumferential direction, which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, and the oil discharge hole is disposed between the first circumferential end of the pressure-side slipper cam surface andIt is formed between the first through hole located on the second circumferential direction side of the first circumferential direction end.

[0009] In the clutch device according to the present invention, the oil discharge hole is formed between the first circumferential end of the pressure-side slipper cam surface and the first through hole located on the second circumferential side of the first circumferential end. Therefore, the clutch oil inside the pressure plate can be efficiently discharged to the outside of the pressure plate through the oil discharge hole, and the clutch oil can be supplied to the input-side rotating plate and the output-side rotating plate.

[0010] 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, the clutch device comprising: a clutch center accommodated in a clutch housing holding a plurality of input side rotating plates which are rotationally driven by the rotational driving of the input shaft and which rotates together with the output shaft; and a pressure plate which is provided so as to be capable of approaching or moving away from the clutch center and being rotatable relative thereto, holds a plurality of output side rotating plates which are arranged alternately with the input side rotating plates, and is capable of pressing the input side rotating plates and the output side rotating plates; The pressure plate includes a plurality of pressure-side cam portions having pressure-side cam surfaces that generate a force in a direction that moves the pressure plate toward or away from the clutch center in order to increase or decrease a pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, a first through hole formed between adjacent pressure-side cam portions, an outer peripheral wall located radially outward from the pressure-side cam portions, and a circumferential projection formed to hold the output side rotating plate and protrude radially outward from the outer peripheral surface of the outer peripheral wall. a plurality of pressure side fitting teeth arranged in a line, a plurality of spline grooves formed between adjacent pressure side fitting teeth, and an oil discharge hole formed in the spline groove so as to penetrate the outer circumferential wall, capable of discharging clutch oil flowing on the inner circumferential side of the outer circumferential wall to the outside of the pressure plate, wherein a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one pressure side cam portion to the other pressure side cam portion in the circumferential direction is defined as a first direction, When the direction toward the cam portion is defined as a first circumferential direction, and the direction from the other pressure side cam portion toward one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction based on the pressure side cam surface formed at the second circumferential end of one of the pressure side cam portions, and the oil discharge hole is formed between the first circumferential end of the pressure side cam surface and the first through hole located on the second circumferential side of the first circumferential end in the circumferential direction.

[0011] In another clutch device according to the present invention, the oil discharge hole is formed between the first circumferential end of the pressure-side cam surface and the first through-hole located on the second circumferential side of the first circumferential end. Therefore, the clutch oil inside the pressure plate can be efficiently discharged to the outside of the pressure plate through the oil discharge hole, and the clutch oil can be supplied to the input-side rotating plate and the output-side rotating plate.

[0012] 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 accommodated in a clutch housing holding a plurality of input side rotating plates which are rotationally driven by the rotational driving of the input shaft and which rotates together with the output shaft; and a pressure plate which is provided so as to be able to approach or move away from the clutch center and to rotate relatively thereto, holds a plurality of output side rotating plates which are arranged alternately with the input side rotating plates, and is capable of pressing the input side rotating plates and the output side rotating plates, and the clutch center is an output shaft holding portion to which the output shaft is connected, and a boss portion located radially outward from the output shaft holding portion and extending toward the pressure plate, the pressure plate having a plurality of pressure side cam portions having pressure side cam surfaces that generate a force in a direction to move the pressure plate toward or away from the clutch center in order to increase or decrease the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, an insertion hole into which the boss portion is inserted, and a boss portion located radially outward from the pressure side cam portions. a plurality of pressure side fitting teeth arranged in a circumferential direction and formed to hold the output side rotating plate and to protrude radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; and an oil discharge hole formed in the spline groove so as to penetrate the outer circumferential wall and for discharging clutch oil flowing on an inner circumferential side of the outer circumferential wall to the outside of the pressure plate, wherein a direction in which the pressure plate approaches the clutch center is defined as a first direction, and a direction in which the pressure plate moves away from the clutch center is defined as a second direction. When the direction of separation is defined as a second direction, and the direction from one of the pressure-side cam portions to the other of the pressure-side cam portions in the circumferential direction is defined as a first circumferential direction, and the direction from the other of the pressure-side cam portions to one of the pressure-side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction based on the pressure-side cam surface formed at an end portion in the second circumferential direction of one of the pressure-side cam portions, and the oil discharge hole is disposed between the second circumferential end portion of the pressure-side cam surface andThe second circumferential end is formed between the insertion hole located on the first circumferential side and the second circumferential end.

[0013] In another clutch device according to the present invention, the oil discharge hole is formed between the second circumferential end of the pressure-side cam surface and the insertion hole located on the first circumferential side of the second circumferential end. Therefore, the clutch oil inside the pressure plate can be efficiently discharged to the outside of the pressure plate through the oil discharge hole, and the clutch oil can be supplied to the input-side rotating plate and the output-side rotating plate.

[0014] 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 accommodated in a clutch housing that holds a plurality of input side rotating plates that are rotationally driven by the rotational driving of the input shaft and that rotates together with the output shaft; and a pressure plate that is arranged to be able to approach or move away from the clutch center and to rotate relatively thereto, holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plates, and is capable of pressing the input side rotating plates and the output side rotating plates; The clutch center includes an output shaft holding portion to which the output shaft is connected, and a boss portion located radially outward of the output shaft holding portion and extending toward the pressure plate. The pressure plate includes a plurality of pressure-side cam portions having pressure-side cam surfaces that generate a force in a direction to move the pressure plate toward or away from the clutch center in order to increase or decrease the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, an insertion hole into which the boss portion is inserted, and a pressure plate having a pressure side cam surface that generates a force in a direction to move the pressure plate toward or away from the clutch center in order to increase or decrease the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center. the pressure plate includes an outer peripheral wall positioned radially outward of a pressure center portion, a plurality of pressure side fitting teeth arranged in a circumferential direction and formed to hold the output side rotating plate and to protrude radially outward from an outer peripheral surface of the outer peripheral wall, a plurality of spline grooves formed between adjacent pressure side fitting teeth, and an oil discharge hole formed in the spline groove so as to penetrate the outer peripheral wall and discharge clutch oil flowing on an inner peripheral side of the outer peripheral wall to the outside of the pressure plate, and a direction in which the pressure plate approaches the clutch center is defined as a first direction, and a direction in which the pressure plate approaches the clutch center is defined as a second direction. a direction in which the pressure plate moves away from the clutch center is defined as a second direction, a direction from one of the pressure side cam portions to the other of the pressure side cam portions in the circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction. The pressure plate is configured to rotate in the first circumferential direction based on the pressure side cam surface formed at an end portion in the second circumferential direction of one of the pressure side cam portions, and the oil discharge hole is configured to rotate in the first circumferential direction based on the pressure side cam surface formed at an end portion in the second circumferential direction of one of the pressure side cam portions in the circumferential direction.The pressure-side assist cam surface is formed on the second circumferential side of a circumferential midpoint between the first circumferential end of the pressure-side assist cam surface and the first circumferential end of the pressure-side slipper cam surface located on the first circumferential side of the first circumferential end.

[0015] In another clutch device according to the present invention, the oil discharge hole is formed on the second circumferential side of the circumferential midpoint between the first circumferential end of the pressure-side assist cam surface and the first circumferential end of the pressure-side slipper cam surface located on the first circumferential side of the first circumferential end. Therefore, the clutch oil inside the pressure plate can be efficiently discharged to the outside of the pressure plate through the oil discharge hole, and the clutch oil can be supplied to the input side rotating plate and the output side rotating plate. Effect of the Invention

[0016] According to the present invention, it is possible to provide a clutch device that can efficiently discharge clutch oil from the inside to the outside of the pressure plate and supply clutch oil to the input side rotating plate and the output side rotating plate. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view of a clutch device according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view of the clutch center according to the first embodiment. [Diagram 3] FIG. 3 is a plan view of the clutch center according to the first embodiment. [Figure 4] FIG. 4 is a perspective view of the pressure plate according to the first embodiment. [Diagram 5] FIG. 5 is a plan view of the pressure plate according to the first embodiment. [Figure 6] FIG. 6 is a perspective view of the pressure plate according to the first embodiment. [Figure 7] FIG. 7 is a plan view of the pressure plate according to the first embodiment. [Figure 8] FIG. 8 is an enlarged side view of a part of the pressure-side cam portion according to the first embodiment. [Figure 9] FIG. 9 is an enlarged perspective view of a portion of the pressure plate according to the first embodiment. [Figure 10] FIG. 10 is a plan view showing a state in which the clutch center and the pressure plate according to the first embodiment are combined. [Figure 11A] FIG. 11A is a schematic diagram for explaining the action of the center side assist cam surface and the pressure side assist cam surface. [Figure 11B] FIG. 11B is a schematic diagram for explaining the action of the center-side slipper cam surface and the pressure-side slipper cam surface. [Figure 12] FIG. 12 is a side view of the clutch center according to the first embodiment. [Figure 13] FIG. 13 is a perspective view of the clutch center according to the second embodiment. [Figure 14] FIG. 14 is an exploded perspective view of the clutch center and the pressure plate according to the third embodiment. [Figure 15] FIG. 15 is a perspective view of a pressure plate according to the third embodiment. [Figure 16] FIG. 16 is a plan view of a pressure plate according to the third embodiment. [Figure 17] FIG. 17 is a side view of a pressure plate according to the third embodiment. [Figure 18] FIG. 18 is a perspective view of a pressure plate according to the fourth embodiment. [Figure 19] FIG. 19 is a perspective view of a pressure plate according to the fifth embodiment. [Figure 20] FIG. 20 is a plan view of a pressure plate according to the fifth embodiment. [Figure 21] FIG. 21 is a side view of the pressure plate according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of a clutch device according to the present invention will be described with reference to the drawings. Note that the embodiment described here is not intended to limit the present invention in any particular way. In addition, the same reference numerals are used for members and parts that perform the same functions, and duplicated descriptions will be omitted or simplified as appropriate.

[0019] First Embodiment Fig. 1 is a cross-sectional view of a clutch device 10 according to a first embodiment. The clutch device 10 is provided on a vehicle such as a motorcycle. The clutch device 10 is a device that transmits or cuts off the rotational driving force of an input shaft (crankshaft) of an engine of the motorcycle to an output shaft 15. The clutch device 10 is a device that transmits or cuts off the rotational driving force of the input shaft to a driving wheel (rear wheel) via the output shaft 15. The clutch device 10 is disposed between the engine and the transmission.

[0020] In the following description, the direction in which the pressure plate 70 of the clutch device 10 approaches and moves away from the clutch center 40 is referred to as direction D, the direction in which the pressure plate 70 approaches the clutch center 40 is referred to as a first direction D1, and the direction in which the pressure plate 70 moves away from the clutch center 40 is referred to as a second direction D2. The circumferential direction of the clutch center 40 and the pressure plate 70 is referred to as a circumferential direction S, the direction from one pressure side cam portion 90 to the other pressure side cam portion 90 in relation to the circumferential direction S (the direction from one center side cam portion 60 to the other center side cam portion 60) is referred to as a first circumferential direction S1 (see FIG. 5), and the direction from the other pressure side cam portion 90 to one pressure side cam portion 90 (the direction from the other center side cam portion 60 to one center side cam portion 60) is referred to as a second circumferential direction S2 (see FIG. 5). 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 the direction D. In addition, the pressure plate 70 and the clutch center 40 rotate in a first circumferential direction S1 (i.e., the direction from the center-side assist cam surface 60A of one center-side cam portion 60 toward the center-side slipper cam surface 60S). However, the above directions are merely defined for the convenience of explanation, and do not limit the installation mode of the clutch device 10 or the present invention in any way.

[0021] As shown in FIG. 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, and a stopper plate 100.

[0022] As shown in Fig. 1, the output shaft 15 is a shaft body formed into a hollow shape. One end of the output shaft 15 rotatably supports an input gear 35 and a clutch housing 30 (described later) via a needle bearing 15A. The output shaft 15 fixedly supports a clutch center 40 via a nut 15B. That is, 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 transmission (not shown) of a motorcycle.

[0023] As shown in FIG. 1, the output shaft 15 includes a push rod 16A in a hollow portion 15H thereof and a push member 16B provided adjacent to the push rod 16A. The hollow portion 15H functions as a flow passage for clutch oil. The clutch oil flows inside the output shaft 15, i.e., inside the hollow portion 15H. The push rod 16A and the push member 16B are provided slidably inside the hollow portion 15H of the output shaft 15. One end (the end on the left side in the figure) of the push rod 16A is connected to a clutch operation lever (not shown) of the motorcycle, and slides inside the hollow portion 15H by operating the clutch operation lever to press the push member 16B in the second direction D2. A part of the push member 16B protrudes outward from the output shaft 15 (here, in the second direction D2) and is connected to a release bearing 18 provided on the pressure plate 70. The push rod 16A and the push member 16B are formed to have a smaller inner diameter than the inner diameter of the hollow portion 15H, ensuring the flow of clutch oil within the hollow portion 15H.

[0024] The clutch housing 30 is made of an aluminum alloy. The clutch housing 30 is formed in a cylindrical shape with a bottom. As shown in Fig. 1, the clutch housing 30 has a bottom wall 31 formed in a substantially circular shape, and a side wall 33 extending in a second direction D2 from an edge of the bottom wall 31. The clutch housing 30 holds a plurality of input side rotating plates 20.

[0025] As shown in Fig. 1, an input gear 35 is provided on a bottom wall 31 of the clutch housing 30. The input gear 35 is fixed to the bottom wall 31 by a rivet 35B via a torque damper 35A. The input gear 35 meshes with a drive gear (not shown) that rotates by the rotational drive of the input shaft of the engine. The input gear 35 is rotated integrally with the clutch housing 30 independently of the output shaft 15.

[0026] The input side rotating plate 20 is rotationally driven by the rotational drive of the input shaft. As shown in Fig. 1, the input side rotating plate 20 is held on the inner circumferential surface of a 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.

[0027] The input side rotating plate 20 is a member 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 a thin plate made of SPCC (cold rolled steel plate) material into an annular shape. Friction materials (not shown) made of multiple pieces of paper are attached to the front and back surfaces of the input side rotating plate 20. Grooves several μm to several tens of μm deep are formed between the friction materials to hold clutch oil.

[0028] As shown in Fig. 1, the clutch center 40 is accommodated in the clutch housing 30. The clutch center 40 is disposed concentrically with the clutch housing 30. The clutch center 40 has a cylindrical main body 42 and a flange 68 extending radially outward from the outer circumferential edge of the main body 42. The clutch center 40 holds an input side rotating plate 20 and a plurality of output side rotating plates 22 arranged alternately in direction D. The clutch center 40 is driven to rotate together with the output shaft 15.

[0029] As shown in FIG. 2, the main body 42 includes an annular base wall 43, an outer peripheral wall 45 located radially outward of the base wall 43 and extending toward the second direction D2, an output shaft holding portion 50 provided in the center of the base wall 43, a plurality of center side cam portions 60 connected to the base wall 43 and the outer peripheral wall 45, and a center side fitting portion 58.

[0030] The output shaft holding portion 50 is formed in a cylindrical shape. An insertion hole 51 into which the output shaft 15 is inserted and spline-fitted is formed in the output shaft holding portion 50. The insertion hole 51 is formed penetrating the base wall 43. An inner circumferential surface 50A of the output shaft holding portion 50 that forms the insertion hole 51 has a plurality of spline grooves formed along the axial direction. The output shaft 15 is connected to the output shaft holding portion 50.

[0031] As shown in FIG. 2, the outer peripheral wall 45 of the clutch center 40 is disposed radially outward from the output shaft holding portion 50. The outer peripheral wall 45 is positioned radially outward from the center side cam portion 60. A spline fitting portion 46 is provided on the outer peripheral surface of the outer peripheral wall 45. The spline fitting portion 46 has a plurality of center side fitting teeth 47 extending in the axial direction of the clutch center 40 along the outer peripheral surface of the outer peripheral wall 45, a plurality of spline grooves 48 formed between adjacent center side fitting teeth 47 and extending in the axial direction of the clutch center 40, and an oil discharge hole 49. The center side fitting teeth 47 hold the output side rotating plate 22. The center side fitting teeth 47 are arranged in the circumferential direction S. The center side fitting teeth 47 are formed at equal intervals in the circumferential direction S. The center side fitting teeth 47 are formed in the same shape. The center side fitting teeth 47 protrude radially outward from the outer circumferential surface of the outer circumferential wall 45 .

[0032] As shown in FIG. 2, the oil discharge hole 49 is formed penetrating the outer peripheral wall 45 in the radial direction. The oil discharge hole 49 is formed between the adjacent center side fitting teeth 47. That is, the oil discharge hole 49 is formed in the spline groove 48. The oil discharge hole 49 is formed on the side of the center side cam portion 60. The oil discharge hole 49 is formed on the side of the center side slipper cam surface 60S of the center side cam portion 60. The oil discharge hole 49 communicates the inside and the outside of the clutch center 40. The oil discharge hole 49 is a hole that can discharge the clutch oil that flows from the output shaft 15 into the clutch center 40 to the outside of the clutch center 40. The oil discharge hole 49 is a hole that discharges the clutch oil flowing on the inner peripheral side of the outer peripheral wall 45 to the outside of the clutch center 40. The oil discharge hole 49 in this embodiment is formed in a circular shape, but the shape is not particularly limited. As shown in FIG. 12, the oil drain hole 49 of this embodiment includes a first oil drain hole 49A located closest to the first direction D1, a second oil drain hole 49B located closer to the second direction D2 than the first oil drain hole 49A, and a third oil drain hole 49C located closer to the second direction D2 than the second oil drain hole 49B. The first oil drain hole 49A, the second oil drain hole 49B, and the third oil drain hole 49C are formed in the same shape (i.e., the same opening area), but may be different. In addition, the oil drain hole 49 includes the first oil drain hole 49A, the second oil drain hole 49B, and the third oil drain hole 49C, but the number of oil drain holes is not limited to three. The first oil drain hole 49A, the second oil drain hole 49B, and the third oil drain hole 49C are formed in different spline grooves 48. 2, the first oil drain hole 49A, the second oil drain hole 49B, and the third oil drain hole 49C are formed along the center-side slipper cam surface 60S. The first oil drain hole 49A and the second oil drain hole 49B are formed, in the circumferential direction S, between an end 60SB in the second circumferential direction S2 of the center-side slipper cam surface 60S and a center-side cam hole 43H (described later) located closer to the first circumferential direction S1 side than the end 60SB in the second circumferential direction S2.The first oil discharge hole 49A is formed between the end 60SD of the center-side slipper cam surface 60S in the first circumferential direction S1 and the center-side cam hole 43H located on the first circumferential direction S1 side of the end 60SD of the first circumferential direction S1 in the circumferential direction S. The first oil discharge hole 49A is formed between the end 60SD of the center-side slipper cam surface 60S in the first circumferential direction S1 and the boss portion 54 located on the first circumferential direction S1 side of the end 60SD of the first circumferential direction S1 in the circumferential direction S. The first oil discharge hole 49A is formed in the spline groove 48A closest to the first circumferential direction S1 with respect to the end 60SD of the center-side slipper cam surface 60S in the first circumferential direction S1. The first oil discharge hole 49A is located radially outside the through hole 43P described later. The first oil discharge hole 49A is located on the first direction D1 side of the surface 43A of the base wall 43. The second oil discharge hole 49B is located on the radial outside of the center-side slipper cam surface 60S. The second oil discharge hole 49B is located on the second direction D2 side of the end 60SD of the center-side slipper cam surface 60S in the first circumferential direction S1. The second oil discharge hole 49B is located on the first direction D1 side of the end 60SB of the center-side slipper cam surface 60S in the second circumferential direction S2. The third oil discharge hole 49C is formed in the center-side fitting portion 58. The third oil discharge hole 49C is located on the second direction D2 side of the end 60SB of the center-side slipper cam surface 60S in the second circumferential direction S2. The third oil discharge hole 49C is located between the center-side slipper cam surface 60S and the center-side assist cam surface 60A with respect to the circumferential direction S.

[0033] As shown in FIG. 12, when the outer peripheral wall 45 is divided into a first portion 45A located on the first direction D1 side and a second portion 45B located on the second direction D2 side with respect to the axial direction of the output shaft 15 (i.e., direction D), the total opening area of ​​the oil discharge holes 49 (here, the second oil discharge hole 49B and the third oil discharge hole 49C) located in the second portion 45B is larger than the total opening area of ​​the oil discharge holes 49 (here, the first oil discharge hole 49A) located in the first portion 45A. In this embodiment, the multiple oil discharge holes 49 have the same shape, the number of the oil discharge holes 49 located in the second portion 45B is two, and the number of the oil discharge holes 49 located in the first portion 45A is one. That is, the number of the oil discharge holes 49 located in the second portion 45B is greater than the number of the oil discharge holes 49 located in the first portion 45A. Furthermore, even if the number of oil drain holes 49 located in the second portion 45B is less than the number of oil drain holes 49 located in the first portion 45A, the total opening area of ​​the oil drain holes 49 located in the second portion 45B may be greater than the total opening area of ​​the oil drain holes 49 located in the first portion 45A due to the difference in shape between the oil drain holes 49 located in the second portion 45B and the oil drain holes 49 located in the first portion 45A.

[0034] The output side rotating plate 22 is held by the spline fitting portion 46 of the clutch center 40 and the pressure plate 70. A part of the output side rotating plate 22 is held by the center side fitting teeth 47 and the spline grooves 48 of the clutch center 40 through spline fitting. Another part of the output side rotating plate 22 is held by pressure side fitting teeth 77 (see FIG. 4 ) of the pressure plate 70, which will be described later. The output side rotating plate 22 is provided so as to be displaceable along the axial direction of the clutch center 40. The output side rotating plate 22 is provided so as to be rotatable integrally with the clutch center 40.

[0035] The output side rotating plate 22 is a member 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 a thin plate material made of SPCC material into an annular shape. Grooves having a depth of several μm to several tens of μm are formed on the front and back surfaces of the output side rotating plate 22 for holding clutch oil. The front and back surfaces of the output side rotating plate 22 are each subjected to a surface hardening treatment in order 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 may be provided on both the input side rotating plate 20 and the output side rotating plate 22.

[0036] The center cam portion 60 is formed in a platform shape having a cam surface made of an inclined surface constituting an Assist & Slipper (registered trademark) mechanism that generates an assist torque, which is a force that increases the pressing force (pressure contact force) between the input side rotating plate 20 and the output side rotating plate 22, or a slipper torque, which is a force that causes the input side rotating plate 20 and the output side rotating plate 22 to separate early and transition to a half-clutch state. The center cam portion 60 is formed so as to protrude from the base wall 43 in the second direction D2. As shown in FIG. 3, the center cam portions 60 are disposed at equal intervals in the circumferential direction S of the clutch center 40. In this embodiment, the clutch center 40 has three center cam portions 60, but the number of center cam portions 60 is not limited to three.

[0037] As shown in FIG. 3, the center-side cam portion 60 is located radially outside the output shaft holding portion 50. The center-side cam portion 60 has a center-side assist cam surface 60A and a center-side slipper cam surface 60S. The center-side assist cam surface 60A is a surface facing the first direction D1. The center-side slipper cam surface 60S is a surface facing the second direction D2. The center-side assist cam surface 60A is configured to generate a force in a direction that moves the pressure plate 70 closer to the clutch center 40 in order to increase the pressing force (pressing force) between the input side rotating plate 20 and the output side rotating plate 22 when rotating relative to the pressure plate 70. 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. Note that the pressure plate 70 may be physically displaced relative to the clutch center 40. The center-side slipper cam surface 60S is configured to move the pressure plate 70 away from the clutch center 40 in order to reduce the pressing force (pressure contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when rotating relative to the pressure plate 70. In the center-side cam portions 60 adjacent to each other in the circumferential direction S, 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 are disposed opposite each other in the circumferential direction S. The center-side slipper cam surface 60S is an example of a center-side cam surface.

[0038] As shown in FIG. 2, the clutch center 40 has a plurality of boss portions 54 (three in this embodiment). The boss portions 54 are members that support the pressure plate 70. The plurality of boss portions 54 are disposed 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 (i.e., toward the second direction D2). The boss portions 54 are provided on the base wall 43. The boss portions 54 are formed with a screw hole 54H into which the bolt 28 (see FIG. 1) is inserted. The screw hole 54H extends in the axial direction of the clutch center 40.

[0039] As shown in FIG. 2, the center-side fitting portion 58 is located radially outward from the output shaft holding portion 50. The center-side fitting portion 58 is located radially outward from the center-side cam portion 60. The center-side fitting portion 58 is located on the second direction D2 side from the center-side cam portion 60. The center-side fitting portion 58 is formed on the inner peripheral surface of the outer peripheral wall 45. The center-side fitting portion 58 is configured to be slidably fitted onto a pressure-side fitting portion 88 (see FIG. 4) described later. The inner diameter of the center-side fitting portion 58 is formed with a fitting tolerance that allows the clutch oil flowing out from the tip portion 15T of the output shaft 15 to flow with respect 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 described later. In this embodiment, for example, the center side fitting portion 58 is formed with an inner diameter that is 0.1 mm larger than the outer diameter of the pressure side fitting portion 88. The dimensional tolerance between the inner diameter of the center side fitting portion 58 and the outer diameter of the pressure side fitting portion 88 is appropriately set according to the amount of clutch oil to be circulated, and is, for example, not less than 0.1 mm and not more than 0.5 mm.

[0040] As shown in FIG. 2 and FIG. 3, the clutch center 40 has a center-side cam hole 43H penetrating a part of the base wall 43. The center-side cam hole 43H penetrates the base wall 43 in the direction D. The center-side cam hole 43H is formed between adjacent center-side cam portions 60. The center-side cam hole 43H extends from the side of the output shaft holding portion 50 to the outer peripheral wall 45. The center-side cam hole 43H is formed between the center-side assist cam surface 60A of the center-side cam portion 60 and the boss portion 54. When viewed from the axial direction of the clutch center 40, the center-side assist cam surface 60A and a part of the center-side cam hole 43H overlap. The center-side cam hole 43H is an example of a first through hole.

[0041] As shown in FIG. 2 and FIG. 3, the clutch center 40 has a through hole 43P penetrating a part of the base wall 43. The through hole 43P penetrates the base wall 43 in the direction D. The through hole 43P is formed between the center side cam portion 60 and the center side cam hole 43H. The through hole 43P is located on the first circumferential direction S1 side of the end portion 60SD of the center side slipper cam surface 60S in the first circumferential direction S1. The through hole 43P is located on the second circumferential direction S2 side of the boss portion 54. The through hole 43P is located radially outward of the boss portion 54. The through hole 43P is adjacent to the center side slipper cam surface 60S. The through hole 43P is smaller than the center side cam hole 43H. The through hole 43P communicates the inside and the outside of the clutch center 40. The through hole 43P is configured to guide the clutch oil flowing outside the clutch center 40 to the inside of the clutch center 40. More specifically, as indicated by the arrow FS in FIG. 1, the clutch oil flowing out from the output shaft 15 toward the clutch center 40 flows into the inside of the clutch center 40 via the through hole 43P. The through hole 43P is in communication with the first oil discharge hole 49A. The through hole 43P is an example of a second through hole.

[0042] As shown in FIG. 1, the pressure plate 70 is provided so as to be capable of approaching or separating from the clutch center 40 and rotatably relative thereto. The pressure plate 70 is configured so as to be capable of pressing the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 70 is arranged concentrically with the clutch center 40 and the clutch housing 30. The pressure plate 70 has a main body 72 and a flange 98 that is connected to the outer circumferential edge of the main body 72 on the second direction D2 side and extends radially outward. The main body 72 protrudes in the first direction D1 beyond the flange 98. The flange 98 is located radially outward beyond a cylindrical portion 80 (see FIG. 4) described later. The pressure plate 70 holds a plurality of output side rotating plates 22 that are alternately arranged with the input side rotating plate 20. The flange 98 is configured so as to be capable of pressing the input side rotating plate 20 and the output side rotating plate 22.

[0043] As shown in FIG. 4, the main body 72 includes a cylindrical portion 80, a plurality of pressure-side cam portions 90, a pressure-side fitting portion 88, and a spring accommodating portion 84 (see also FIG. 6).

[0044] 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. The cylindrical portion 80 accommodates the release bearing 18 (see FIG. 1). The cylindrical portion 80 is a portion that receives a pressing force from the push member 16B. The cylindrical portion 80 is a portion that receives the clutch oil that flows out from the tip portion 15T of the output shaft 15.

[0045] The pressure-side cam portion 90 is formed in a platform shape having a cam surface made of an inclined surface constituting an Assist & Slipper (registered trademark) mechanism that slides on the center-side cam portion 60 to generate an assist torque or a slipper torque. The pressure-side cam portion 90 is formed so as to protrude in a first direction D1 beyond the flange 98. As shown in FIG. 5, the pressure-side cam portions 90 are disposed 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.

[0046] As shown in FIG. 5, the pressure-side cam portion 90 is located on the radial outside of the cylindrical portion 80. The pressure-side cam portion 90 has a pressure-side assist cam surface 90A (see also FIG. 7 and FIG. 9) and a pressure-side slipper cam surface 90S. The pressure-side assist cam surface 90A is a surface facing the second direction D2. The pressure-side slipper cam surface 90S is a surface facing the first direction D1, and the pressure-side assist cam surface 90A is configured to be able to come into contact with the center-side assist cam surface 60A. The pressure-side assist cam surface 90A is configured to generate a force in a direction that moves the pressure plate 70 closer to the clutch center 40 in order to increase the pressing force (pressing force) between the input side rotating plate 20 and the output side rotating plate 22 when rotating relative to the clutch center 40. The pressure-side slipper cam surface 90S is configured to be able to come into contact with the center-side slipper cam surface 60S. The pressure-side slipper cam surface 90S is configured to move the pressure plate 70 away from the clutch center 40 in order to reduce the pressing force (pressing force) between the input side rotating plate 20 and the output side rotating plate 22 when rotating relative to the clutch center 40. In the pressure-side cam portions 90 adjacent to each other in 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 disposed opposite each other in the circumferential direction S. The pressure-side slipper cam surface 90S is an example of a pressure-side cam surface.

[0047] As shown in Fig. 8, a chamfered portion 90AP is formed by linearly chamfering an end portion in the circumferential direction S of the pressure-side assist cam surface 90A of the pressure-side cam portion 90. The corner of the chamfered portion 90AP (the corner on the first direction D1 and first circumferential direction S1 side) is a right angle. More specifically, the chamfered portion 90AP is formed at an end portion 90AB in the first circumferential direction S1 of the pressure-side assist cam surface 90A.

[0048] Here, the action of the center side cam portion 60 and the pressure side cam portion 90 will be described. When the engine speed increases and the rotational driving force input to the input gear 35 and the clutch housing 30 can be transmitted to the output shaft 15 via the clutch center 40, a rotational force in the first circumferential direction S1 is applied to the pressure plate 70 as shown in Fig. 11A. Therefore, a force in the first direction D1 is generated on the pressure plate 70 due to the action of the center side assist cam surface 60A and the pressure side assist cam surface 90A. This increases the pressing force between the input side rotating plate 20 and the output side rotating plate 22.

[0049] On the other hand, when the rotation speed of the output shaft 15 exceeds the rotation speed of the input gear 35 and the clutch housing 30 and back torque is generated, a rotational force in the first circumferential direction S1 is applied to the clutch center 40 as shown in Fig. 11B. Therefore, the action of the center side slipper cam surface 60S and the pressure side slipper cam surface 90S moves the pressure plate 70 in the second direction D2 to release the pressure contact force between the input side rotating plate 20 and the output side rotating plate 22. This makes it possible to avoid malfunctions of the engine and transmission due to back torque.

[0050] 4, 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 second direction D2 side from the pressure-side cam portion 90. The pressure-side fitting portion 88 is configured to be slidably fitted into the center-side fitting portion 58 (see FIG. 2).

[0051] As shown in Figs. 4 and 5, the pressure plate 70 has a pressure-side cam hole 73H penetrating a part of the main body 72 and the flange 98. The pressure-side cam hole 73H is located radially outward from the cylindrical portion 80. The pressure-side cam hole 73H extends from the side of the cylindrical portion 80 to a position radially outward from the pressure-side fitting portion 88. 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 the adjacent pressure-side cam portion 90. As shown in Figs. 5 and 7, when viewed from the axial direction of the pressure plate 70, the pressure-side assist cam surface 90A and a part of the pressure-side cam hole 73H overlap each other.

[0052] As shown in FIG. 4, the pressure plate 70 has a plurality of pressure side fitting teeth 77 arranged on a flange 98. The pressure side fitting teeth 77 hold the output side rotating plate 22. The pressure side fitting teeth 77 protrude from the flange 98 in a first direction D1. The pressure side fitting teeth 77 are located radially outward from the cylindrical portion 80. They are located radially outward from the pressure side cam portion 90. The pressure side fitting teeth 77 are located radially outward from the pressure side cam portion 90. The pressure side fitting teeth 77 are located radially outward from the pressure side fitting portion 88. The pressure side fitting teeth 77 are aligned in the circumferential direction S. The pressure side fitting teeth 77 are arranged at equal intervals in the circumferential direction S. In this embodiment, since some of the pressure side fitting teeth 77 are removed, the intervals in those portions are wider, but the other adjacent pressure side fitting teeth 77 are disposed at equal intervals.

[0053] As shown in Figs. 6 and 7, the spring accommodating portion 84 is formed in the pressure-side cam portion 90. The spring accommodating portion 84 is formed so as to be recessed from the second direction D2 to the first direction D1. The spring accommodating portion 84 is formed in an elliptical shape. The spring accommodating portion 84 accommodates the pressure spring 25 (see Fig. 1). An insertion hole 84H into which the boss portion 54 (see Fig. 2) is inserted is formed through the spring accommodating portion 84. That is, the insertion hole 84H is formed through the pressure-side cam portion 90. The insertion hole 84H is formed in an elliptical shape.

[0054] 1, the pressure spring 25 is accommodated in the spring accommodating portion 84. The pressure spring 25 is held by the boss portion 54 inserted into the insertion hole 84H of the spring accommodating portion 84. The pressure spring 25 biases the pressure plate 70 toward the clutch center 40 (i.e., toward the first direction D1). The pressure spring 25 is, for example, a coil spring formed by winding spring steel in a spiral shape.

[0055] FIG. 10 is a plan view showing a state in which the clutch center 40 and the pressure plate 70 are assembled. In the state shown in FIG. 10, the pressure side assist cam surface 90A and the center side assist cam surface 60A are not in contact with each other, and the pressure side slipper cam surface 90S and the center side slipper cam surface 60S are not in contact with each other. At this time, the pressure plate 70 is closest to the clutch center 40. This state is defined as the normal state of the clutch device 10. As shown in FIG. 10, the distance L5 in the circumferential direction S between the boss portion 54 and the end 84HA of the insertion hole 84H on the pressure side assist cam surface 90A side (i.e., the first circumferential direction S1 side) in the normal state is shorter than the distance L6 in the circumferential direction S between the boss portion 54 and the end 84HB of the insertion hole 84H on the pressure side slipper cam surface 90S side (i.e., the second circumferential direction S2 side) in the normal state.

[0056] As shown in Fig. 1, the stopper plate 100 is provided so as to be able to come into 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 the second direction D2 by more than a predetermined distance. The stopper plate 100 is fixed to the boss portion 54 of the clutch center 40 by the bolt 28. The pressure plate 70 is fixed by tightening the bolt 28 to the boss portion 54 via the stopper plate 100 in a state in which the boss portion 54 of the clutch center 40 and the pressure spring 25 are arranged in the spring accommodating portion 84. The stopper plate 100 is formed in a substantially triangular shape in a plan view.

[0057] Here, when the pressure plate 70 contacts the stopper plate 100, the pressure-side slipper cam surface 90S and the center-side slipper cam surface 60S are in contact with each other over 50% to 90% of the area of ​​the pressure-side slipper cam surface 90S and over 50% to 90% of the area of ​​the center-side slipper cam surface 60S, respectively. Also, when the pressure plate 70 contacts the stopper plate 100, the pressure spring 25 is separated from the side wall of the spring accommodating portion 84. That is, the pressure spring 25 is not sandwiched between the boss portion 54 and the spring accommodating portion 84, and excessive stress is prevented from being applied to the boss portion 54.

[0058] Here, the circumferential length L1 (see Figure 5) from the end 90AB in the first circumferential direction S1 of the pressure side assist cam surface 90A located on the first circumferential direction S1 side of one pressure side cam portion 90L of the pressure side cam portions 90 adjacent to each other in the circumferential direction S to the end 90SB in the first circumferential direction S1 of the pressure side slipper cam surface 90S located on the second circumferential direction S2 side of the other pressure side cam portion 90M is longer than the circumferential length L2 (see Figure 3) from the end 60AB in the second circumferential direction S2 of the center side assist cam surface 60A of one center side cam portion 60 to the end 60SB in the second circumferential direction S2 of the center side slipper cam surface 60S.

[0059] Furthermore, when viewed from the axial direction of the output shaft 15, the angle θ1 (see Figure 5) formed by the center 80C of the cylindrical portion 80 and the end 90AB in the first circumferential direction S1 of the pressure side assist cam surface 90A located on the first circumferential direction S1 side of one of the pressure side cam portions 90L of the pressure side cam portions 90 adjacent to each other in the circumferential direction S, and the end 90SB in the first circumferential direction S1 of the pressure side slipper cam surface 90S located on the second circumferential direction S2 side of the other pressure side cam portion 90M, is greater than the angle θ2 (see Figure 3) formed by the center 50C of the output shaft holding portion 50 and the end 60AB in the second circumferential direction S2 of the center side assist cam surface 60A of one center side cam portion 60, and the end 60SB in the second circumferential direction S2 of the center side slipper cam surface 60S.

[0060] In addition, the length L3 (see Figure 3) in the circumferential direction S from the end 60AB in the second circumferential direction S2 of the center side assist cam surface 60A to the boss portion 54 is longer than the length L4 (see Figure 5) in the circumferential direction S from the end 90AB in the first circumferential direction S1 of the pressure side assist cam surface 90A to the insertion hole 84H.

[0061] Furthermore, when viewed from the axial direction of the output shaft 15, the angle θ3 (see Figure 3) formed by the center 50C of the output shaft holding portion 50, the end portion 60AB in the second circumferential direction S2 of the center side assist cam surface 60A of the center side cam portion 60, and the center 54C of the boss portion 54 is greater than the angle θ4 (see Figure 5) formed by the center 80C of the tubular portion 80, the end portion 90AB in the first circumferential direction S1 of the pressure side assist cam surface 90A, and the center 84HC of the insertion hole 84H.

[0062] A predetermined amount of clutch oil is filled in the clutch device 10. The clutch oil flows through the hollow portion 15H of the output shaft 15 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 the oil discharge hole 49. The clutch oil also flows from the outside of the clutch center 40 through the hollow portion 15H of the output shaft 15 to the inside of the clutch center 40 through the through hole 43P. The clutch oil present inside the clutch center 40 has a tendency to gather in front of the center side slipper cam surface 60S of the center side cam portion 60 due to centrifugal force because the clutch center 40 rotates in the first circumferential direction S1. The clutch oil absorbs heat and suppresses wear of the friction material. The clutch device 10 of this embodiment is a so-called wet type multi-plate friction clutch device.

[0063] Next, the operation of the clutch device 10 of this embodiment will be described. As described above, the clutch device 10 is disposed between the engine and the transmission of the motorcycle, and transmits or cuts off the rotational driving force of the engine to the transmission when the rider operates the clutch operating lever.

[0064] In the clutch device 10, when the rider of the motorcycle does not operate the clutch operating lever, the clutch release mechanism (not shown) does not press the push rod 16A, and the pressure plate 70 presses the input side rotating plate 20 by the biasing force (elastic force) of the pressure spring 25. As a result, the clutch center 40 is in a clutch-on state in which the input side rotating plate 20 and the output side rotating plate 22 are pressed against each other and frictionally connected, and is driven to rotate. That is, the rotational driving force of the engine is transmitted to the clutch center 40, and the output shaft 15 is driven to rotate.

[0065] In the clutch ON state, the clutch oil that flows inside the hollow portion H of the output shaft 15 and flows out from the tip end 15T of the output shaft 15 drops or flies into the cylindrical portion 80 and adheres thereto (see arrow F in FIG. 1). The clutch oil that adheres to the inside of the cylindrical portion 80 is guided into the clutch center 40. As a result, the clutch oil flows out to the outside of the clutch center 40 through the oil discharge hole 49. The clutch oil also flows out to the outside of the clutch center 40 through the gap between the center side fitting portion 58 and the pressure side fitting portion 88. The clutch oil that flows out to the outside of the clutch center 40 is then supplied to the input side rotating plate 20 and the output side rotating plate 22.

[0066] On the other hand, when the rider of the motorcycle operates the clutch operating lever in the clutch ON state, the clutch release mechanism (not shown) presses the push rod 16A, and the pressure plate 70 is displaced in a direction (second direction D2) away from the clutch center 40 against the biasing force of the pressure spring 25. As a result, the clutch center 40 enters a clutch OFF state in which the frictional connection between the input side rotating plate 20 and the output side rotating plate 22 is released, and the rotational drive is attenuated or stopped. In other words, the rotational drive force of the engine is cut off from the clutch center 40.

[0067] In the clutch OFF state, the clutch oil that flows inside the hollow portion H of the output shaft 15 and flows out from the tip portion 15T of the output shaft 15 is led into the clutch center 40, just as in the clutch ON state. At this time, the pressure plate 70 is separated from the clutch center 40, so the amount of engagement between the center side fitting portion 58 and the pressure side fitting portion 88 decreases. As a result, the clutch oil in the cylindrical portion 80 flows out of the clutch center 40 more actively and flows to various places inside the clutch device 10. In particular, the clutch oil can be actively led between the input side rotating plate 20 and the output side rotating plate 22, which are separated from each other.

[0068] When the driver releases the clutch operating lever in the clutch OFF state, the pressure applied to the pressure plate 70 by the clutch release mechanism (not shown) via the push member 16B is released, and the pressure plate 70 is displaced in a direction approaching the clutch center 40 (first direction D1) by the force of the pressure spring 25.

[0069] As described above, according to the clutch device 10 of this embodiment, the clutch center 40 is configured to rotate in the first circumferential direction S1, which is the direction from the center-side assist cam surface 60A of one center-side cam portion 60 to the center-side slipper cam surface 60S. Therefore, the clutch oil present inside the clutch center 40 moves from the center-side cam hole 43H side to the center-side slipper cam surface 60S side along the outer peripheral wall 45 by centrifugal force. Here, the oil discharge hole 49 is formed between the end 60SB of the center-side slipper cam surface 60S in the second circumferential direction S2 and the center-side cam hole 43H located on the first circumferential direction S1 side of the end 60SB in the second circumferential direction S2 with respect to the circumferential direction S. Therefore, the clutch oil inside the clutch center 40 can be efficiently discharged to the outside of the clutch center 40 through the oil discharge hole 49, and the clutch oil can be supplied to the input side rotating plate 20 and the output side rotating plate 22.

[0070] In the clutch device 10 of this embodiment, the first oil drain hole 49A is formed between the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S and the center-side cam hole 43H located on the first circumferential direction S1 side of the end 60SD in the first circumferential direction S1 in relation to the circumferential direction S. According to the above aspect, the clutch oil inside the clutch center 40 can be more efficiently discharged to the outside of the clutch center 40 via the first oil drain hole 49A.

[0071] In the clutch device 10 of this embodiment, the clutch center 40 is located radially outward from the output shaft holding portion 50 and includes a boss portion 54 extending toward the pressure plate 70, and the first oil drain hole 49A is formed between the end portion 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S and the boss portion 54 located on the first circumferential direction S1 side relative to the end portion 60SD in the first circumferential direction S1 in relation to the circumferential direction S. According to the above aspect, the clutch oil inside the clutch center 40 can be more efficiently discharged to the outside of the clutch center 40 via the first oil drain hole 49A.

[0072] In the clutch device 10 of this embodiment, the clutch center 40 has a through hole 43P located on the first circumferential direction S1 side of the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S, and the through hole 43P is configured to guide the clutch oil flowing outside the clutch center 40 to the inside of the clutch center 40. According to the above aspect, since a large amount of clutch oil flows near the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S, the first oil drain hole 49A is formed near that portion, so that the clutch oil inside the clutch center 40 can be more efficiently discharged to the outside of the clutch center 40.

[0073] In the clutch device 10 of this embodiment, the clutch center 40 has a plurality of oil drain holes 49, and when the outer peripheral wall 45 is equally divided into a first portion 45A located on the first direction D1 side with respect to the axial direction of the output shaft 15 (i.e., direction D) and a second portion 45B located on the second direction D2 side, the total opening area of ​​the oil drain holes 49 located in the second portion 45B is greater than the total opening area of ​​the oil drain holes 49 located in the first portion 45A. According to the above aspect, the clutch oil inside the clutch center 40 can be discharged further toward the pressure plate 70.

[0074] In the clutch device 10 of this embodiment, when the multiple oil drain holes 49 have the same shape, the number of oil drain holes 49 located in the second portion 45B is greater than the number of oil drain holes 49 located in the first portion 45A. According to the above aspect, the clutch oil inside the clutch center 40 can be discharged further toward the pressure plate 70.

[0075] In the clutch device 10 of this embodiment, the clutch center 40 has a plurality of oil drain holes 49, and the plurality of oil drain holes 49 are formed along the center side slipper cam surface 60S. According to the above aspect, the clutch oil moving along the center side slipper cam surface 60S can be efficiently discharged to the outside of the clutch center 40.

[0076] In the clutch device 10 of this embodiment, the clutch center 40 has a plurality of oil drain holes 49, and the plurality of oil drain holes 49 are located closer to the first circumferential direction S1 as they are located closer to the first direction D1. According to the above aspect, the clutch oil moving along the center-side slipper cam surface 60S can be efficiently discharged to the outside of the clutch center 40.

[0077] In the clutch device 10 of this embodiment, the oil drain hole 49 is formed in the spline groove 48A that is closest to the first circumferential direction S1 relative to the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S. According to the above aspect, since clutch oil is most likely to accumulate near the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S, by forming the first oil drain hole 49A in the spline groove 48A near that portion, the clutch oil inside the clutch center 40 can be more efficiently discharged to the outside of the clutch center 40.

[0078] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

[0079] <Second embodiment> In the first embodiment described above, the clutch center 40 has a through hole 43P penetrating the base wall 43 in the direction D, but is not limited thereto. FIG. 13 is a perspective view of a clutch center 140 according to a second embodiment. As shown in FIG. 13, the clutch center 140 has a recess 143 on the surface 43A of the base wall 43. The recess 143 is formed so as to be recessed in the first direction D1 from the surface 43A. The recess 143 is located on the first direction D1 side of the end 60SD in the first circumferential direction S1 of the center side slipper cam surface 60S. The recess 143 is formed between the center side cam portion 60 and the center side cam hole 43H. The recess 143 is located on the first circumferential direction S1 side of the end 60SD in the first circumferential direction S1 of the center side slipper cam surface 60S. The recess 143 is located on the second circumferential direction S2 side of the boss portion 54. The recess 143 is located radially outward from the boss portion 54. The recess 143 is adjacent to the center side slipper cam surface 60S. The recess 143 is smaller than the center side cam hole 43H. The recess 143 has a function of retaining clutch oil. The first oil discharge hole 49A is located radially outward from the recess 143.

[0080] In the clutch device 10 of this embodiment, the clutch center 140 has a recess 143 that is located on the first circumferential direction S1 side of the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S and is formed so as to recess toward the first direction D1. According to the above aspect, since clutch oil is most likely to accumulate near the end 60SD in the first circumferential direction S1 of the center-side slipper cam surface 60S, by providing the recess 143 near this portion, it is possible to hold a larger amount of clutch oil. Then, the clutch oil held in the recess 143 can be efficiently discharged to the outside of the clutch center 40.

[0081] In the clutch device 10 of the present embodiment, the first oil drain hole 49A is located radially outside the recess 143. According to the above aspect, the clutch oil held in the recess 143 can be more efficiently discharged to the outside of the clutch center 40 through the first oil drain hole 49A.

[0082] In the first and second embodiments described above, the oil drain hole 49 includes the first oil drain hole 49A, the second oil drain hole 49B, and the third oil drain hole 49C, but may include an oil drain hole other than the first oil drain hole 49A to the third oil drain hole 49C. The oil drain hole 49 may include at least one of the first oil drain hole 49A to the third oil drain hole 49C. The oil drain hole 49 may include at least one of the first oil drain hole 49A to the third oil drain hole 49C and an oil drain hole other than the first oil drain hole 49A to the third oil drain hole 49C. The number of the other oil drain holes described above may be one or more.

[0083] <Third embodiment> FIG. 14 is an exploded perspective view of a clutch center 240 and a pressure plate 270 of a clutch device 210 according to the third embodiment.

[0084] The clutch center 240 is accommodated in the clutch housing 30 (see FIG. 1). The clutch center 240 is disposed concentrically with the clutch housing 30. As shown in FIG. 14, the clutch center 240 has a main body 242 and a flange 268 that is connected to the outer circumferential edge of the main body 242 on the first direction D1 side and extends radially outward. The main body 242 protrudes in the second direction D2 beyond the flange 268. The clutch center 240 does not hold the output side rotating plate 22. The clutch center 240 is driven to rotate together with the output shaft 15 (see FIG. 1).

[0085] 14, the main body 242 includes an output shaft holding portion 250, a plurality of center side cam portions 60, and a center side fitting portion 258. The center side cam portion 60 is formed so as to protrude in the second direction D2 beyond the flange 268. The center side cam portion 60 is located radially outward of the output shaft holding portion 250.

[0086] The output shaft holding portion 250 is formed in a cylindrical shape. An insertion hole 251 into which the output shaft 15 (see FIG. 1) is inserted and spline-fitted is formed in the output shaft holding portion 250. The insertion hole 251 is formed penetrating the main body 242. An inner circumferential surface 250A of the output shaft holding portion 250 that forms the insertion hole 251 has a plurality of spline grooves formed along the axial direction. The output shaft 15 is connected to the output shaft holding portion 250.

[0087] 14, the clutch center 240 has a plurality of (three in this embodiment) boss portions 54. The boss portions 54 are located radially outward from the output shaft holding portion 250. The boss portions 54 are provided on the main body 242.

[0088] 14, the clutch center 240 has a center-side cam hole 243H that penetrates the main body 242 and a portion of the flange 268. The center-side cam hole 243H penetrates the main body 242 and the flange 268 in direction D. The center-side cam hole 243H extends from the side of the output shaft holding portion 250 to the flange 268. The center-side cam hole 243H is formed between the center-side assist cam surface 60A of the center-side cam portion 60 and the boss portion 54. When viewed from the axial direction of the clutch center 240, the center-side assist cam surface 60A and a portion of the center-side cam hole 243H overlap with each other.

[0089] 14, the center side fitting portion 258 is provided on the main body 242. The center side fitting portion 258 is located radially outward from the center side cam portion 60. The center side fitting portion 258 is located on the first direction D1 side from the center side cam portion 60. The center side fitting portion 258 is configured to be slidably fitted into the pressure side fitting portion 288 (see FIG. 12).

[0090] The pressure plate 270 is provided so as to be capable of approaching or separating from the clutch center 240 and rotatable relative thereto. The pressure plate 270 is configured so as to be able to press the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 270 is arranged concentrically with the clutch center 240 and the clutch housing 30. The pressure plate 270 has a cylindrical main body 272 and a flange 298 extending radially outward from the outer circumferential edge of the main body 272. The pressure plate 270 holds the input side rotating plate 20 and the multiple output side rotating plates 22 arranged alternately in the direction D.

[0091] As shown in FIG. 15, the main body 272 includes an annular base wall 273, an outer peripheral wall 275 located radially outward of the base wall 273 and extending in the first direction D1, a cylindrical portion 280 provided in the center of the base wall 273, a plurality of pressure-side cam portions 90 connected to the base wall 273 and the outer peripheral wall 275, a pressure-side fitting portion 288, and a spring accommodating portion 84 (see FIG. 11). The pressure-side cam portion 90 is formed so as to protrude from the main body 272 in the first direction D1. The pressure-side cam portion 90 is located radially outward of the cylindrical portion 280. The pressure-side cam portion 90 is located radially inward of the outer peripheral wall 275.

[0092] The cylindrical portion 280 is formed in a cylindrical shape. The cylindrical portion 280 is formed integrally with the pressure side cam portion 90. The cylindrical portion 280 accommodates the tip portion 15T (see FIG. 1) of the output shaft 15. The cylindrical portion 280 accommodates the release bearing 18 (see FIG. 1). The cylindrical portion 280 is a portion that receives a pressing force from the push member 16B. The cylindrical portion 280 is a portion that receives the clutch oil that flows out from the tip portion 15T of the output shaft 15.

[0093] As shown in FIG. 15, the outer peripheral wall 275 of the pressure plate 270 is disposed radially outward from the cylindrical portion 280. The outer peripheral wall 275 is formed in an annular shape extending in the direction D. A spline fitting portion 276 is provided on an outer peripheral surface 275A of the outer peripheral wall 275. The spline fitting portion 276 has a plurality of pressure side fitting teeth 277 extending in the axial direction of the pressure plate 270 along the outer peripheral surface 275A of the outer peripheral wall 275, a plurality of spline grooves 278 formed between adjacent pressure side fitting teeth 277 and extending in the axial direction of the pressure plate 270, and an oil discharge hole 279. The pressure side fitting teeth 277 hold the output side rotating plate 22. The pressure side fitting teeth 277 are arranged in the circumferential direction S. The pressure side fitting teeth 277 are formed at equal intervals in the circumferential direction S. The pressure-side fitting teeth 277 are formed in the same shape. The pressure-side fitting teeth 277 protrude from an outer circumferential surface 275A of the outer circumferential wall 275 outward in the radial direction.

[0094] As shown in FIG. 15, the oil discharge hole 279 is formed penetrating the outer peripheral wall 275 in the radial direction. The oil discharge hole 279 is formed between the adjacent pressure side fitting teeth 277. That is, the oil discharge hole 279 is formed in the spline groove 278. The oil discharge hole 279 is formed on the side of the pressure side cam portion 90. The oil discharge hole 279 is formed on the side of the pressure side slipper cam surface 90S of the pressure side cam portion 90. The oil discharge hole 279 communicates the inside and the outside of the pressure plate 270. The oil discharge hole 279 is a hole that can discharge the clutch oil that flows from the output shaft 15 into the pressure plate 270 to the outside of the pressure plate 270. The oil discharge hole 279 is a hole that discharges the clutch oil flowing on the inner peripheral side of the outer peripheral wall 275 to the outside of the pressure plate 270. In this embodiment, the oil drain hole 279 is formed in a circular shape, but the shape is not particularly limited.

[0095] As shown in Fig. 17, the oil discharge hole 279 of this embodiment includes a first oil discharge hole 279A located closest to the second direction D2, a second oil discharge hole 279B located closer to the first direction D1 than the first oil discharge hole 279A, a third oil discharge hole 279C located closer to the first direction D1 than the second oil discharge hole 279B, and a fourth oil discharge hole 279D located closer to the first direction D1 than the third oil discharge hole 279C. The first oil discharge hole 279A, the second oil discharge hole 279B, the third oil discharge hole 279C, and the fourth oil discharge hole 279D are formed to have the same shape (i.e., the same opening area), but may be different. In addition, the oil discharge hole 279 includes the first oil discharge hole 279A, the second oil discharge hole 279B, the third oil discharge hole 279C, and the fourth oil discharge hole 279D, but the number of oil discharge holes is not limited to four. The first oil discharge hole 279A, the second oil discharge hole 279B, the third oil discharge hole 279C, and the fourth oil discharge hole 279D are formed in different spline grooves 278. As shown in Fig. 15, the first oil discharge hole 279A, the second oil discharge hole 279B, the third oil discharge hole 279C, and the fourth oil discharge hole 279D are formed along the pressure-side slipper cam surface 90S.

[0096] As shown in FIG. 15, the first oil discharge hole 279A, the second oil discharge hole 279B, and the third oil discharge hole 279C are formed between the end 90SB of the pressure-side slipper cam surface 90S in the first circumferential direction S1 and the pressure-side cam hole 273H, which is located on the second circumferential direction S2 side of the end 90SB in the first circumferential direction S1, in the circumferential direction S. The first oil discharge hole 279A is formed between the end 90SD of the pressure-side slipper cam surface 90S in the second circumferential direction S2 and the pressure-side cam hole 273H, which is located on the second circumferential direction S2 side of the end 90SD in the second circumferential direction S2, in the circumferential direction S. The first oil discharge hole 279A is located radially outside the through hole 273P, which is described later. The second oil discharge hole 279B and the third oil discharge hole 279C are located radially outside the pressure-side slipper cam surface 90S. The second oil discharge hole 279B and the third oil discharge hole 279C are located on the first circumferential direction S1 side of the end 90SD of the pressure side slipper cam surface 90S in the second circumferential direction S2. The second oil discharge hole 279B and the third oil discharge hole 279C are located on the first direction D1 side of the end 90SD of the pressure side slipper cam surface 90S in the second circumferential direction S2. The second oil discharge hole 279B and the third oil discharge hole 279C are located on the second circumferential direction S2 side of the end 90SB of the pressure side slipper cam surface 90S in the first circumferential direction S1. The second oil discharge hole 279B and the third oil discharge hole 279C are located on the second direction D2 side of the end 90SB of the pressure side slipper cam surface 90S in the first circumferential direction S1. The second oil discharge hole 279B is formed in the spline groove 278A closest to the second circumferential direction S2 relative to the end 90SD in the second circumferential direction S2 of the pressure-side slipper cam surface 90S. The fourth oil discharge hole 279D is formed in the pressure-side fitting portion 288. The fourth oil discharge hole 279D is located on the first direction D1 side of the end 90SB in the first circumferential direction S1 of the pressure-side slipper cam surface 90S. The fourth oil discharge hole 279D is located between the pressure-side slipper cam surface 90S and the pressure-side assist cam surface 90A in the circumferential direction S.The fourth oil discharge hole 279D is formed between the end 90SD in the second circumferential direction S2 of the pressure-side slipper cam surface 90S and the insertion hole 84H located on the first circumferential direction S1 side of the end 90SD in the second circumferential direction S2 in the circumferential direction S. The fourth oil discharge hole 279D is located between the end 90SB in the first circumferential direction S1 of the pressure-side slipper cam surface 90S and the insertion hole 84H located on the first circumferential direction S1 side of the end 90SB in the first circumferential direction S1 in the circumferential direction S.

[0097] As shown in FIG. 17, when the outer peripheral wall 275 is divided into a first portion 285A located on the first direction D1 side and a second portion 285B located on the second direction D2 side with respect to the axial direction of the output shaft 15 (i.e., direction D), the total opening area of ​​the oil discharge holes 279 (here, the second oil discharge hole 279B, the third oil discharge hole 279C, and the fourth oil discharge hole 279D) located in the first portion 285A is larger than the total opening area of ​​the oil discharge holes 279 (here, the first oil discharge hole 279A) located in the second portion 285B. In this embodiment, the multiple oil discharge holes 279 have the same shape, the number of the oil discharge holes 279 located in the first portion 285A is three, and the number of the oil discharge holes 279 located in the second portion 285B is one. That is, the number of the oil discharge holes 279 located in the first portion 285A is greater than the number of the oil discharge holes 279 located in the second portion 285B. Furthermore, even if the number of oil drain holes 279 located in first portion 285A is less than the number of oil drain holes 279 located in second portion 276B, the total opening area of ​​oil drain holes 279 located in first portion 285A may be greater than the total opening area of ​​oil drain holes 279 located in second portion 285B due to the difference in shape between oil drain holes 279 located in first portion 285A and oil drain holes 279 located in second portion 285B.

[0098] The output side rotating plate 22 is held by a spline fitting portion 276 of the pressure plate 270. The output side rotating plate 22 is held by spline fitting to pressure side fitting teeth 277 and spline grooves 278. The output side rotating plate 22 is provided so as to be displaceable along the axial direction of the pressure plate 270. The output side rotating plate 22 is provided so as to be rotatable integrally with the pressure plate 270.

[0099] As shown in FIG. 15, the pressure side fitting portion 288 is located radially outward from the cylindrical portion 280. The pressure side fitting portion 288 is located radially outward from the pressure side cam portion 90. The pressure side fitting portion 288 is located closer to the first direction D1 than the pressure side cam portion 90. The pressure side fitting portion 288 is formed on the inner peripheral surface 275B of the outer peripheral wall 275. The pressure side fitting portion 288 is configured to be slidably fitted onto the center side fitting portion 258 (see FIG. 14). A gap is formed between the pressure side fitting portion 288 and the center side fitting portion 258.

[0100] As shown in FIG. 15 and FIG. 16, the pressure plate 270 has a pressure-side cam hole 273H penetrating a part of the base wall 273. The pressure-side cam hole 273H is an example of a first through hole. The pressure-side cam hole 273H penetrates the base wall 273 in the direction D. The pressure-side cam hole 273H is located radially outward from the cylindrical portion 80. The pressure-side cam hole 273H extends from the side of the cylindrical portion 80 to the outer peripheral wall 275. The pressure-side cam hole 273H is formed penetrating between the adjacent pressure-side cam portions 90. The pressure-side cam hole 273H is formed penetrating between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S of the adjacent pressure-side cam portions 90. The pressure-side assist cam surface 90A and a portion of the pressure-side cam hole 273H overlap when viewed from the axial direction of the pressure plate 270. Clutch oil flows from the outside of the pressure plate 270 into the pressure-side cam hole 273H.

[0101] As shown in FIG. 15 and FIG. 16, the pressure plate 270 has a through hole 273P penetrating a part of the base wall 273. The through hole 273P penetrates the base wall 273 in the direction D. The through hole 273P is formed between the pressure side cam portion 90 and the pressure side cam hole 273H. The through hole 273P is located on the second circumferential direction S2 side of the end portion 90SD of the pressure side slipper cam surface 90S in the second circumferential direction S2. The through hole 273P is adjacent to the pressure side slipper cam surface 90S. The through hole 273P is smaller than the pressure side cam hole 273H. The through hole 273P communicates the inside and the outside of the pressure plate 270. The through hole 273P is configured to guide the clutch oil flowing outside the pressure plate 270 to the inside of the pressure plate 270. The through hole 273P is an example of a second through hole.

[0102] As described above, in the clutch device 210 of this embodiment, the oil discharge hole 279 is formed between the end 90SB in the first circumferential direction S1 of the pressure-side slipper cam surface 90S and the pressure-side cam hole 273H located on the second circumferential direction S2 side of the end 90SB in the first circumferential direction S1 in relation to the circumferential direction S. Therefore, the clutch oil inside the pressure plate 270 can be efficiently discharged to the outside of the pressure plate 270 via the oil discharge hole 279, and the clutch oil can be supplied to the input side rotating plate 20 and the output side rotating plate 22.

[0103] In the clutch device 210 of this embodiment, the first oil drain hole 279A is formed between the end 90SD in the second circumferential direction S2 of the pressure-side slipper cam surface 90S and the pressure-side cam hole 273H located on the second circumferential direction S2 side of the end 90SD in the second circumferential direction S2 in relation to the circumferential direction S. According to the above aspect, the clutch oil inside the pressure plate 270 can be more efficiently discharged to the outside of the pressure plate 270 via the first oil drain hole 279A.

[0104] In the clutch device 210 of this embodiment, the pressure plate 270 has a through hole 273P located on the second circumferential direction S2 side of the end 90SD of the pressure side slipper cam surface 90S in the second circumferential direction S2, and the through hole 273P is configured to be able to guide the clutch oil flowing outside the pressure plate 270 to the inside of the pressure plate 270. According to the above aspect, since a large amount of clutch oil flows near the end 90SD of the pressure side slipper cam surface 90S in the second circumferential direction S2, the first oil discharge hole 279A is formed near that portion, so that the clutch oil inside the pressure plate 270 can be more efficiently discharged to the outside of the pressure plate 270.

[0105] In the clutch device 210 of this embodiment, the pressure plate 270 has a plurality of oil discharge holes 279, and when the outer peripheral wall 275 is equally divided into a first portion 285A located on the first direction D1 side with respect to the axial direction of the output shaft 15 (i.e., direction D) and a second portion 285B located on the second direction D2 side, the total opening area of ​​the oil discharge holes 279 located in the first portion 285A is larger than the total opening area of ​​the oil discharge holes 279 located in the second portion 285B. According to the above aspect, the clutch oil inside the pressure plate 270 can be more effectively discharged to the clutch center 240.

[0106] In the clutch device 210 of this embodiment, when the multiple oil drain holes 279 have the same shape, the number of oil drain holes 279 located in the first portion 285A is greater than the number of oil drain holes 279 located in the second portion 285B. According to the above aspect, the clutch oil inside the pressure plate 270 can be discharged further toward the clutch center 240.

[0107] In the clutch device 210 of this embodiment, the pressure plate 270 has a plurality of oil discharge holes 279, and the plurality of oil discharge holes 279 are formed along the pressure-side slipper cam surface 90S. According to the above-described aspect, the clutch oil moving along the pressure-side slipper cam surface 90S can be efficiently discharged to the outside of the pressure plate 270.

[0108] In the clutch device 210 of this embodiment, the pressure plate 270 has a plurality of oil discharge holes 279, and the plurality of oil discharge holes 279 are located closer to the second circumferential direction S2 as they are located closer to the second direction D2. According to the above aspect, the clutch oil moving along the pressure-side slipper cam surface 90S can be efficiently discharged to the outside of the pressure plate 270.

[0109] In the clutch device 210 of this embodiment, the oil discharge hole 279 is formed in the spline groove 278A that is closest to the second circumferential direction S2 with respect to the end 90SD in the second circumferential direction S2 of the pressure-side slipper cam surface 90S. According to the above aspect, since clutch oil is likely to accumulate near the end 90SD in the second circumferential direction S2 of the pressure-side slipper cam surface 90S, by forming the second oil discharge hole 279B in the spline groove 278A near that portion, the clutch oil inside the pressure plate 270 can be more efficiently discharged to the outside of the pressure plate 270.

[0110] <Fourth embodiment> In the above-described third embodiment, the pressure plate 270 has the through hole 273P penetrating the base wall 273 in the direction D, but is not limited thereto. FIG. 18 is a perspective view of a pressure plate 370 according to a fourth embodiment. As shown in FIG. 18, the pressure plate 370 has a recess 373 in place of the through hole 273P in the surface 273A of the base wall 273. The recess 373 is formed so as to be recessed in the second direction D2 from the surface 273A. The recess 373 is located on the second direction D2 side of the end 90SD in the second circumferential direction S2 of the pressure side slipper cam surface 90S. The recess 373 is formed between the pressure side cam portion 90 and the pressure side cam hole 273H. The recess 373 is located on the second circumferential direction S2 side of the end 90SD in the second circumferential direction S2 of the pressure side slipper cam surface 90S. The recess 373 is adjacent to the pressure side slipper cam surface 90S. The recess 373 is smaller than the pressure side cam hole 273H. The recess 373 has a function of retaining clutch oil. A first oil discharge hole 279A is located radially outward of the recess 373.

[0111] In the clutch device 210 of this embodiment, the pressure plate 270 has a recess 373 that is located on the second circumferential direction S2 side of the end 90SD in the second circumferential direction S2 of the pressure side slipper cam surface 90S and is formed so as to recess toward the second direction D2 side. According to the above aspect, since clutch oil is likely to accumulate near the end 90SD in the second circumferential direction S2 of the pressure side slipper cam surface 90S, by providing the recess 373 near the portion, it is possible to hold more clutch oil. Then, the clutch oil held in the recess 373 can be efficiently discharged to the outside of the pressure plate 270.

[0112] In the clutch device 210 of the present embodiment, the first oil discharge hole 279A is located radially outside the recess 373. According to the above-described aspect, the clutch oil held in the recess 373 can be more efficiently discharged to the outside of the pressure plate 270 through the first oil discharge hole 379A.

[0113] <Fifth embodiment> 19, a pressure plate 470 of the clutch device 210 according to the fifth embodiment has a splined fitting portion 476. The splined fitting portion 476 has a plurality of pressure-side fitting teeth 277, a plurality of spline grooves 278, and an oil discharge hole 479.

[0114] As shown in FIG. 19, the oil discharge hole 479 is formed by penetrating the outer peripheral wall 275 in the radial direction. The oil discharge hole 479 is formed between the adjacent pressure side fitting teeth 277. That is, the oil discharge hole 479 is formed in the spline groove 278. As shown in FIG. 20, the oil discharge hole 479 is formed on the second circumferential direction S2 side of the midpoint 90C in the circumferential direction S between the end 90AB in the first circumferential direction S1 of the pressure side assist cam surface 90A and the end 90SB in the first circumferential direction S1 of the pressure side slipper cam surface 90S located on the first circumferential direction S1 side from the end 90AB in the first circumferential direction S1. The center line 90CL in FIG. 21 is a straight line parallel to the direction D and passing through the midpoint 90C. As shown in FIG. 21, when viewed from the radial direction of the pressure plate 470, at least one oil discharge hole 479 is located on the second circumferential direction S2 side of the end 90AB of the pressure side assist cam surface 90A in the first circumferential direction S1. When viewed from the radial direction of the pressure plate 470, the oil discharge hole 479 is located on the first circumferential direction S1 side of the end 90AD of the pressure side assist cam surface 90A in the second circumferential direction S2. The oil discharge hole 479 communicates the inside and the outside of the pressure plate 470. The oil discharge hole 479 is a hole that can discharge the clutch oil that flows into the pressure plate 470 from the output shaft 15 to the outside of the pressure plate 470. The oil discharge hole 479 is a hole that discharges the clutch oil flowing on the inner circumferential side of the outer circumferential wall 275 to the outside of the pressure plate 470. In this embodiment, the oil drain hole 479 is formed in a circular shape, but the shape is not particularly limited.

[0115] As shown in Fig. 21, the oil drain hole 479 of this embodiment includes a fifth oil drain hole 479E located closest to the second direction D2, a sixth oil drain hole 479F located closer to the first direction D1 than the fifth oil drain hole 479E, a seventh oil drain hole 479G located closer to the first direction D1 than the sixth oil drain hole 479F, and an eighth oil drain hole 479H located closer to the first direction D1 than the seventh oil drain hole 479G. The fifth oil drain hole 479E, the sixth oil drain hole 479F, the seventh oil drain hole 479G, and the eighth oil drain hole 479H are formed in the same shape (i.e., the same opening area), but may be different. In addition, the oil drain hole 479 includes the fifth oil drain hole 479E, the sixth oil drain hole 479F, the seventh oil drain hole 479G, and the eighth oil drain hole 479H, but the number of oil drain holes is not limited to four. The fifth oil drain hole 479E, the sixth oil drain hole 479F, the seventh oil drain hole 479G, and the eighth oil drain hole 479H are formed in different spline grooves 278. As shown in Fig. 19, the fifth oil drain hole 479E, the sixth oil drain hole 479F, the seventh oil drain hole 479G, and the eighth oil drain hole 479H are formed along the pressure-side assist cam surface 90A.

[0116] As shown in FIG. 20, the fifth oil discharge hole 479E, the sixth oil discharge hole 479F, and the seventh oil discharge hole 479G are formed between the end 90AD of the pressure-side assist cam surface 90A in the second circumferential direction S2 and the midpoint 90C in the circumferential direction S. The fifth oil discharge hole 479E is located radially outside the pressure-side assist cam surface 90A. The fifth oil discharge hole 479E is formed between the end 90AB of the pressure-side assist cam surface 90A in the first circumferential direction S1 and the end 90AD of the pressure-side assist cam surface 90A in the second circumferential direction S2 in the circumferential direction S. The fifth oil discharge hole 479E and the sixth oil discharge hole 479F are formed radially outside the pressure-side cam hole 273H. The seventh oil discharge hole 479G is formed between the pressure-side cam hole 273H and the midpoint 90C in the circumferential direction S. The eighth oil drain hole 479H is formed in the pressure-side fitting portion 288. The eighth oil drain hole 479H is formed, in the circumferential direction S, between the midpoint 90C and the end portion 90SD in the second circumferential direction S2 of the pressure-side slipper cam surface 90S.

[0117] 21, the total opening area of ​​the oil discharge holes 479 (here, the sixth oil discharge hole 479F, the seventh oil discharge hole 479G, and the eighth oil discharge hole 479H) located in the first portion 285A is greater than the total opening area of ​​the oil discharge holes 479 (here, the fifth oil discharge hole 479E) located in the second portion 285B. In this embodiment, the multiple oil discharge holes 479 have the same shape, the number of the oil discharge holes 479 located in the first portion 285A is three, and the number of the oil discharge holes 479 located in the second portion 285B is one. That is, the number of the oil discharge holes 479 located in the first portion 285A is greater than the number of the oil discharge holes 479 located in the second portion 285B. Furthermore, even if the number of oil drain holes 479 located in first portion 285A is less than the number of oil drain holes 479 located in second portion 276B, the total opening area of ​​oil drain holes 479 located in first portion 285A may be greater than the total opening area of ​​oil drain holes 479 located in second portion 285B due to the difference in shape between oil drain holes 479 located in first portion 285A and oil drain holes 479 located in second portion 285B.

[0118] According to the clutch device 210 of this embodiment, the oil discharge hole 479 is formed on the second circumferential direction S2 side of the midpoint 90C in the circumferential direction S between the end 90AB in the first circumferential direction S1 of the pressure-side assist cam surface 90A and the end 90SB in the first circumferential direction S1 of the pressure-side slipper cam surface 90S located on the first circumferential direction S1 side of the end 90AB in the first circumferential direction S1. Therefore, the clutch oil inside the pressure plate 470 can be efficiently discharged to the outside of the pressure plate 470 through the oil discharge hole 479, and the clutch oil can be supplied to the input side rotating plate 20 and the output side rotating plate 22.

[0119] According to the clutch device 210 of this embodiment, when viewed from the radial direction of the pressure plate 470, at least one oil discharge hole 479 is located on the second circumferential direction S2 side of the end 90AB in the first circumferential direction S1 of the pressure-side assist cam surface 90A. According to the above aspect, the clutch oil that has flowed to the pressure-side assist cam surface 90A through the oil discharge hole 479 can be efficiently discharged to the outside of the pressure plate 470.

[0120] In the third and fourth embodiments described above, the oil discharge hole 279 includes the first oil discharge hole 279A, the second oil discharge hole 279B, the third oil discharge hole 279C, and the fourth oil discharge hole 279D, but may include an oil discharge hole other than the first oil discharge hole 279A to the fourth oil discharge hole 279D. Also, the oil discharge hole 279 may include at least one of the first oil discharge hole 279A to the fourth oil discharge hole 279D. Furthermore, the oil discharge hole 279 may include at least one of the first oil discharge hole 279A to the fourth oil discharge hole 279D and an oil discharge hole other than the first oil discharge hole 279A to the fourth oil discharge hole 279D. The number of the other oil discharge holes described above may be one or more. Also, in the third and fourth embodiments, the oil discharge hole 479 of the fifth embodiment may be included.

[0121] In the above-mentioned fifth embodiment, the oil discharge hole 479 includes the fifth oil discharge hole 479E, the sixth oil discharge hole 479F, the seventh oil discharge hole 479G, and the eighth oil discharge hole 479H, but may include an oil discharge hole other than the fifth oil discharge hole 479E to the eighth oil discharge hole 479H. In addition, the oil discharge hole 479 may include at least one of the fifth oil discharge hole 479E to the eighth oil discharge hole 479H. Furthermore, the oil discharge hole 479 may include at least one of the fifth oil discharge hole 479E to the eighth oil discharge hole 479H, and an oil discharge hole other than the fifth oil discharge hole 479E to the eighth oil discharge hole 479H. The above-mentioned other oil discharge hole may be one or more. In addition, in the fifth embodiment, the oil discharge hole 279 of the third and fourth embodiments may be included.

[0122] In the above-described third, fourth and fifth embodiments, the clutch center 240 is configured so as not to hold the output side rotating plate 22, but is not limited to this. The clutch center 240 may have center side fitting teeth having a similar configuration to the pressure side fitting teeth 77 of the first embodiment that can hold the output side rotating plate 22.

[0123] In each of the above-described embodiments, a plurality of oil drain holes 49, 279, and 479 are provided, but some of them may be disposed at positions other than those specified in the respective independent claims. In other words, all of the oil drain holes 49, 279, and 479 do not have to be disposed at the positions specified in the respective independent claims. [Explanation of symbols]

[0124] 15 Output shaft 20 Input side rotating plate 22 Output side rotating plate 30 Clutch housing 60 Center side cam part 60A Center side assist cam surface 60S Center side slipper cam surface 84H Insertion hole 90 Pressure side cam part 90A Pressure side assist cam surface 90AB first circumferential end 90C midpoint 90S Pressure side slipper cam surface 90SB First circumferential end 90SD Second circumferential end 210 Clutch device 270 Pressure Plate 273H Pressure side cam hole (first through hole) 273P through hole (2nd through hole) 275 Outer wall 277 Pressure side mating teeth 278 Spline groove 279 Oil drain hole 373 Recess 479 Oil drain hole

Claims

1. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; an oil discharge hole that is formed in the spline groove so as to penetrate the outer peripheral wall and that is capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, The oil discharge hole is formed between the second circumferential end of the pressure-side slipper cam surface and the first through hole located on the second circumferential side of the second circumferential end, The pressure plate is a second through hole located on the second circumferential side of the second circumferential end of the pressure-side slipper cam surface, The second through hole is configured to be able to guide clutch oil flowing outside the pressure plate to the inside of the pressure plate.

2. A clutch device for transmitting or interrupting the rotational drive force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; an oil discharge hole that is formed in the spline groove so as to penetrate the outer peripheral wall and that is capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, The oil discharge hole is formed between the first circumferential end of the pressure-side slipper cam surface and the first through hole located on the second circumferential side of the first circumferential end, The pressure plate has a plurality of the oil discharge holes, a clutch device, wherein when the outer peripheral wall is divided into two equal parts, a first part located on the first direction side in the axial direction of the output shaft, and a second part located on the second direction side, a sum of the opening areas of the oil drain holes located in the first part is greater than a sum of the opening areas of the oil drain holes located in the second part.

3. 3. The clutch device according to claim 2, wherein when the plurality of oil drain holes have the same shape, the number of the oil drain holes located in the first portion is greater than the number of the oil drain holes located in the second portion.

4. A clutch device for transmitting or interrupting the rotational drive force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; an oil discharge hole that is formed in the spline groove so as to penetrate the outer peripheral wall and that is capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, The oil discharge hole is formed between the first circumferential end of the pressure-side slipper cam surface and the first through hole located on the second circumferential side of the first circumferential end, The pressure plate has a plurality of the oil discharge holes, A clutch device, wherein the oil discharge holes are formed along the pressure side slipper cam surface.

5. A clutch device for transmitting or interrupting the rotational drive force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; an oil discharge hole that is formed in the spline groove so as to penetrate the outer peripheral wall and that is capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, a clutch device, wherein the oil discharge hole is formed, in a circumferential direction, between the first circumferential end of the pressure-side slipper cam surface and the first through hole located on the second circumferential side of the first circumferential end, and is formed in the spline groove closest in the second circumferential direction to the second circumferential end of the pressure-side slipper cam surface.

6. A clutch device for transmitting or interrupting the rotational drive force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; an oil discharge hole that is formed in the spline groove so as to penetrate the outer peripheral wall and that is capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, The oil discharge hole is formed between the first circumferential end of the pressure-side slipper cam surface and the first through hole located on the second circumferential side of the first circumferential end, The pressure plate is a clutch device having a recess located on the second circumferential side of the second circumferential end of the pressure-side slipper cam surface and formed so as to be recessed toward the second circumferential side.

7. The clutch device according to claim 6 , wherein the oil drain hole is located radially outward of the recess.

8. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The clutch center is an output shaft holding portion to which the output shaft is connected; a boss portion located radially outward from the output shaft holding portion and extending toward the pressure plate, The pressure plate is a plurality of pressure-side cam portions having pressure-side cam surfaces that move the pressure plate away from the clutch center in order to reduce a pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center; an insertion hole into which the boss portion is inserted; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; a plurality of oil discharge holes formed in the spline groove so as to penetrate the outer peripheral wall and discharge clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction with respect to the pressure-side cam surface formed at an end portion of one of the pressure-side cam portions in the second circumferential direction, A clutch device, wherein the multiple oil discharge holes include, in a circumferential direction, a first oil discharge hole formed between the second circumferential end of the pressure-side cam surface and the insertion hole located on the first circumferential side of the second circumferential end, and a second oil discharge hole located on the second circumferential side of the second circumferential end of the pressure-side cam surface.

9. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The clutch center is an output shaft holding portion to which the output shaft is connected; a boss portion located radially outward from the output shaft holding portion and extending toward the pressure plate, The pressure plate is a plurality of pressure-side cam portions having pressure-side cam surfaces that generate a force in a direction that moves the pressure plate closer to the clutch center in order to increase a pressing force between the input-side rotating plate and the output-side rotating plate when the pressure plate rotates relative to the clutch center; an insertion hole into which the boss portion is inserted; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; a plurality of oil discharge holes formed in the spline groove so as to penetrate the outer peripheral wall and discharge clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate, When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction with respect to the pressure-side cam surface formed at an end portion of one of the pressure-side cam portions in the second circumferential direction, A clutch device, wherein the multiple oil discharge holes include, in a circumferential direction, a first oil discharge hole formed between the first circumferential end of the pressure-side cam surface and the insertion hole located on the second circumferential side of the first circumferential end, and a second oil discharge hole located on the first circumferential side of the first circumferential end of the pressure-side cam surface.

10. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; a plurality of oil discharge holes formed in the spline groove so as to penetrate the outer peripheral wall and capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate; When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, the plurality of oil discharge holes are located in a circumferential direction between an end portion of the one pressure-side cam portion in the first circumferential direction and an end portion of the other pressure-side cam portion in the first circumferential direction, A clutch device, wherein the multiple oil discharge holes include a first oil discharge hole located on the first circumferential side of the second circumferential end of the other pressure side cam portion, and a second oil discharge hole located on the second circumferential side of the second circumferential end of the other pressure side cam portion.

11. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; a plurality of oil discharge holes formed in the spline groove so as to penetrate the outer peripheral wall and capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate; When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, the plurality of oil discharge holes are located between the second circumferential end of the one pressure-side assist cam surface and the first circumferential end of the other pressure-side slipper cam surface in a circumferential direction, A clutch device, wherein the multiple oil discharge holes include a first oil discharge hole located on the second circumferential side of the first circumferential end of the one of the pressure side cam portions, and a second oil discharge hole located on the first circumferential side of the first circumferential end of the one of the pressure side cam portions.

12. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; a plurality of oil discharge holes formed in the spline groove so as to penetrate the outer peripheral wall and capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate; When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, A clutch device, wherein the oil drain holes are located further toward the second circumferential direction as they are positioned toward the second direction side.

13. The clutch device according to any one of claims 10 to 12, wherein the clutch center is configured so as not to hold the output side rotating plate.

14. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be capable of approaching or separating from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that is capable of pressing the input side rotating plate and the output side rotating plate, The pressure plate is a plurality of pressure-side cam portions each having a pressure-side assist cam surface that generates a force in a direction that moves the pressure plate closer to the clutch center in order to increase the pressing force between the input side rotating plate and the output side rotating plate when the pressure plate rotates relative to the clutch center, and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input side rotating plate and the output side rotating plate; a first through hole formed between adjacent pressure-side cam portions; an outer circumferential wall located radially outward of the pressure side cam portion; a plurality of pressure side fitting teeth arranged in a circumferential direction, the pressure side fitting teeth being arranged to hold the output side rotating plate and protruding radially outward from an outer circumferential surface of the outer circumferential wall; a plurality of spline grooves formed between adjacent pressure side fitting teeth; a plurality of oil discharge holes formed in the spline groove so as to penetrate the outer peripheral wall and capable of discharging clutch oil flowing along an inner peripheral side of the outer peripheral wall to an outside of the pressure plate; When a direction in which the pressure plate approaches the clutch center is defined as a first direction, a direction in which the pressure plate moves away from the clutch center is defined as a second direction, and a direction from one of the pressure side cam portions to the other of the pressure side cam portions in a circumferential direction is defined as a first circumferential direction, and a direction from the other of the pressure side cam portions to one of the pressure side cam portions is defined as a second circumferential direction, the pressure plate is configured to rotate in the first circumferential direction which is a direction from the pressure-side slipper cam surface of one of the pressure-side cam portions to the pressure-side assist cam surface, The clutch device, wherein the multiple oil drain holes include a first oil drain hole formed in a portion of the outer peripheral wall located radially outward from the first through hole, and a second oil drain hole formed in a portion of the outer peripheral wall located on the first circumferential side of the portion located radially outward from the first through hole.

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