Clutch device

Abstract

In a clutch device 210, in a state where a center-side assist cam surface 60A and a pressure-side assist cam surface 90A are in contact with each other, a gap 259 is formed between a clutch center 240 and a pressure plate 270 in a direction D, and a center-side center line 247L and a pressure-side center line 277L1 do not overlap each other when viewed from the axial direction of an output shaft 15.

Description

Clutch device

[0001] The present invention relates to a clutch device.

[0002] Conventionally, vehicles such as motorcycles have a clutch device. For example, Patent Document 1 discloses a clutch device including a clutch center that holds a part of an output-side rotating plate, and a pressure plate that is provided so as to be able to approach and separate from the clutch center and holds a part of the output-side rotating plate. The clutch center and the pressure plate each include an annular outer peripheral wall and a plurality of fitting teeth protruding radially outward from the outer peripheral surface of the outer peripheral wall, and the output-side rotating plate is held by the fitting teeth.

[0003] Further, the clutch center and the pressure plate of the clutch device of Patent Document 1 include an assist cam surface that generates a force directed from the pressure plate toward the clutch center to increase the pressing force between the input-side rotating plate and the output-side rotation, and a slipper cam surface that separates the pressure plate from the clutch center to reduce the pressing force between the input-side rotating plate and the output-side rotation.

[0004] Japanese Patent Application Laid-Open No. 2018-204655

[0005] By the way, in the clutch device described in Patent Document 1, the contact between the assist cam surface of the pressure plate and the assist cam surface of the clutch center, and the contact between the slipper cam surface of the pressure plate and the slipper cam surface of the clutch center occur frequently. Therefore, in order to suppress wear of each assist cam surface and slipper cam surface and generation of abnormal noise during contact, it is desired to effectively supply clutch oil to the assist cam surface and the slipper cam surface.

[0006] The present invention has been made in view of such points, and an object thereof is to provide a clutch device capable of effectively supplying clutch oil to an assist cam surface and a slipper cam surface.

[0007] The clutch device according to the present invention is a clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that holds a plurality of input-side rotating plates that are rotationally driven by the rotational drive of the input shaft, and which holds a portion of a plurality of output-side rotating plates arranged alternately with the input-side rotating plates, and which is rotationally driven together with the output shaft; and a pressure plate provided so as to be able to approach and move away from the clutch center, which holds a portion of the plurality of output-side rotating plates, and which is capable of pressing the input-side rotating plates and the output-side rotating plates, wherein the clutch center has an annular center-side outer peripheral wall extending in the direction of movement when the direction in which the pressure plate approaches and moves away from the clutch center is the direction of movement, a plurality of center-side fitting teeth arranged in the circumferential direction that hold the output-side rotating plates and project radially outward from the outer peripheral surface of the center-side outer peripheral wall, and the pressure plate to increase the pressing force between the input-side rotating plates and the output-side rotating plates when it rotates relative to the pressure plate. The pressure plate comprises a center-side assist cam surface that generates a force in the direction toward the clutch center from the center, and a plurality of center-side cam portions having center-side slipper cam surfaces that separate the pressure plate from the clutch center in order to reduce the pressing force between the input-side rotating plate and the output-side rotating plate, wherein the pressure plate has an annular pressure-side outer peripheral wall extending in the direction of movement, and a circumferentially arranged wall that holds the output-side rotating plate and is formed to protrude radially outward from the outer peripheral surface of the pressure-side outer peripheral wall. The device comprises a plurality of pressure-side fitting teeth, a plurality of pressure-side cam portions having a pressure-side assist cam surface that generates a force in the direction toward the clutch center from the pressure plate to increase the pressing force between the input-side rotating plate and the output-side rotating plate when rotated relative to the clutch center, and a pressure-side slipper cam surface that separates the pressure plate from the clutch center to decrease the pressing force between the input-side rotating plate and the output-side rotating plate, and when viewed from the axial direction of the output shaft,At least a portion of the annular center ring portion, which is radially enclosed by the center tip circle passing through the tip of the tooth located most radially outward among the center mating teeth and the center root circle passing through the root of the tooth located most radially inward among the center mating teeth, overlaps with the annular pressure ring portion, which is radially enclosed by the pressure tip circle passing through the tip of the tooth located most radially outward among the pressure mating teeth and the pressure root circle passing through the root of the tooth located most radially inward among the pressure mating teeth, In the state in which the center-side assist cam surface and the pressure-side assist cam surface are in contact, a gap is formed between the clutch center and the pressure plate with respect to the direction of movement, and in the state in which the center-side assist cam surface and the pressure-side assist cam surface are in contact, when viewed from the axial direction of the output shaft, the center-side center line passing through the circumferential center of the center-side fitting tooth and the center of the output shaft does not coincide with the pressure-side center line passing through the circumferential center of the pressure-side fitting tooth and the center of the output shaft.

[0008] In the clutch device according to the present invention, when the center-side assist cam surface and the pressure-side assist cam surface are in contact, the center-side centerline passing through the circumferential center of the center-side mating tooth and the center of the output shaft, when viewed from the axial direction of the output shaft, does not coincide with the pressure-side centerline passing through the circumferential center of the pressure-side mating tooth and the aforementioned center of the force axis. That is, when the center-side assist cam surface and the pressure-side assist cam surface are in contact, the center-side mating tooth and the pressure-side mating tooth are offset in the circumferential direction. For this reason, for example, the clutch oil flowing along the outer peripheral wall of the center side toward the pressure-side mating tooth hits the end of the pressure-side mating tooth and flows from the gap between the pressure plate and the clutch center toward the center-side assist cam surface, the pressure-side assist cam surface, the center-side slipper cam surface, and the pressure-side slipper cam surface. In this way, when the center assist cam surface and the pressure assist cam surface are in contact, clutch oil can be effectively supplied to the center assist cam surface, the pressure assist cam surface, the center slipper cam surface, and the pressure slipper cam surface.

[0009] According to the present invention, a clutch device can be provided that can effectively supply clutch oil to the assist cam surface and the slipper cam surface.

[0010] Figure 1 is a cross-sectional view of the clutch device according to the first embodiment. Figure 2 is a perspective view of the clutch center according to the first embodiment. Figure 3 is a plan view of the clutch center according to the first embodiment. Figure 4 is a perspective view of the clutch center according to the first embodiment. Figure 5 is a plan view of the clutch center according to the first embodiment. Figure 6 is a perspective view of the pressure plate according to the first embodiment. Figure 7 is a plan view of the pressure plate according to the first embodiment. Figure 8 is a perspective view of the pressure plate according to the first embodiment. Figure 9 is a plan view of the pressure plate according to the first embodiment. Figure 10A is a schematic diagram illustrating the operation of the center-side assist cam surface and the pressure-side assist cam surface. Figure 10B is a schematic diagram illustrating the operation of the center-side slipper cam surface and the pressure-side slipper cam surface. Figure 11 is a schematic diagram showing the positional relationship between the center-side annular portion and the pressure-side annular portion when viewed from the axial direction of the output shaft. Figure 12 is a plan view showing the clutch center and pressure plate as viewed from the axial direction of the output shaft, in a state where the center-side assist cam surface and the pressure-side assist cam surface are in contact. Figure 13 is a side view showing a state where a part of the center-side projection and the pressure-side spline groove overlap when viewed from the radial direction of the output shaft. Figure 14 is a side view showing a state where a gap is formed between the center-side projection and the pressure plate when viewed from the radial direction of the output shaft. Figure 15 is a side view showing the relationship between the outermost output-side rotating plate and the center-side projection when viewed from the radial direction of the output shaft. Figure 16 is a side view showing a state where a part of the pressure-side projection and the center-side spline groove overlap when viewed from the radial direction of the output shaft. Figure 17 is a cross-sectional view of the clutch device according to the second embodiment. Figure 18 is a perspective view of the clutch center according to the second embodiment. Figure 19 is a plan view of the clutch center according to the second embodiment. Figure 20 is a perspective view of the clutch center according to the second embodiment. Figure 21 is a plan view of the clutch center according to the second embodiment. Figure 22 is a perspective view of the pressure plate according to the second embodiment. Figure 23 is a plan view of the pressure plate according to the second embodiment. Figure 24 is a perspective view of the pressure plate according to the second embodiment. Figure 25 is a plan view of the pressure plate according to the second embodiment.Figure 26 is a schematic diagram showing the positional relationship between the center-side annular portion and the pressure-side annular portion when viewed from the axial direction of the output shaft. Figure 27 is a schematic diagram showing the positional relationship between the center-side mating teeth and the pressure-side mating teeth when viewed from the axial direction of the output shaft. Figure 28 is a schematic diagram showing the positional relationship between the center-side mating teeth and the pressure-side mating teeth when viewed from the axial direction of the output shaft. Figure 29 is a schematic diagram showing the positional relationship between the center-side mating teeth and the pressure-side mating teeth when viewed from the axial direction of the output shaft. Figure 30 is a table showing the positional relationship between the center-side mating teeth and the pressure-side mating teeth when viewed from the axial direction of the output shaft. Figure 31 is a side view showing the state in which the center line of the center-side spline groove and the center line of the pressure-side spline groove are located on the same straight line when viewed from the radial direction of the output shaft. Figure 32 is a plan view showing the clutch center and pressure plate as seen from the axial direction of the output shaft, in a state where the center-side assist cam surface and the pressure-side assist cam surface are in contact. Figure 33 is a side view showing a state where a part of the pressure-side projection and the center-side spline groove overlap when viewed from the radial direction of the output shaft. Figure 34 is a side view showing a state where a gap is formed between the pressure-side projection and the clutch center when viewed from the radial direction of the output shaft. Figure 35 is a side view showing the relationship between the outermost output-side rotating plate and the pressure-side projection when viewed from the radial direction of the output shaft. Figure 36 is a side view showing a state where a part of the center-side projection and the pressure-side spline groove overlap when viewed from the radial direction of the output shaft. Figure 37 is a schematic diagram showing the positional relationship between the center-side centerline and the pressure-side centerline when viewed from the axial direction of the output shaft according to the third embodiment. Figure 38 is a side view showing the positional relationship between the center-side centerline and the pressure-side centerline when viewed from the radial direction of the output shaft, in a state where the center-side assist cam surface and the pressure-side assist cam surface are in contact. Figure 39 is a side view showing the positional relationship between the center-side centerline and the pressure-side centerline when viewed from the radial direction of the output shaft, in a state where the pressure plate is furthest away from the clutch center. Figure 40 is a schematic diagram showing the positional relationship between the center-side centerline and the pressure-side centerline when viewed from the axial direction of the output shaft according to the fourth embodiment.

[0011] Hereinafter, embodiments of the clutch device according to the present invention will be described with reference to the drawings. Naturally, the embodiments described herein are not intended to particularly limit the present invention. Furthermore, the same reference numerals are used for members and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate.

[0012] <First Embodiment> Figure 1 is a cross-sectional view of a clutch device 10 according to the first embodiment. The clutch device 10 is installed in a vehicle such as a motorcycle. The clutch device 10 is a device that transmits or interrupts the rotational driving force of the input shaft (crankshaft) of a power source such as the engine of a motorcycle to the output shaft 15. The clutch device 10 is a device for transmitting or interrupting the rotational driving force of the input shaft to the drive wheel (rear wheel) via the output shaft 15. The clutch device 10 is positioned between the engine and the transmission.

[0013] 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 the first direction D1, and the direction in which the pressure plate 70 moves away from the clutch center 40 is referred to as the second direction D2. Direction D is an example of a direction of movement. Furthermore, the circumferential direction of the clutch center 40 and the pressure plate 70 is referred to as the circumferential direction S, the direction from one side to the other with respect to the circumferential direction S is referred to as the first circumferential direction S1 (see Figure 2), and the direction from the other side to the one side is referred to as the second circumferential direction S2 (see Figure 2). In this embodiment, the axial direction of the output shaft 15, the axial direction of the clutch housing 30, the axial direction of the clutch center 40, and the axial direction of the pressure plate 70 are the same as direction D. Also, the pressure plate 70 and the clutch center 40 rotate in the first circumferential direction S1 during normal operation. However, the directions described above are merely defined for the sake of explanation and do not in any way limit the installation configuration of the clutch device 10, nor do they limit the present invention in any way.

[0014] As shown in Figure 1, the clutch device 10 includes an output shaft 15, an input side rotating plate 20, an output side rotating plate 22, a clutch housing 30, a clutch center 40, a pressure plate 70, and a stopper plate 100.

[0015] As shown in Figure 1, the output shaft 15 is a hollow shaft. One end of the output shaft 15 rotatably supports the input gear 35 and clutch housing 30, which will be described later, via a bearing 15A. The output shaft 15 fixedly supports the clutch center 40 via a washer 15D and a nut 15N. 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 motor vehicle or motorcycle.

[0016] The clutch housing 30 is made of an aluminum alloy. The clutch housing 30 is formed in a bottomed cylindrical shape. As shown in Figure 1, the clutch housing 30 has a substantially circular bottom wall 31 and side walls 33 extending in direction D from the edge of the bottom wall 31. The clutch housing 30 holds a plurality of input-side rotating plates 20.

[0017] As shown in Figure 1, an input gear 35 is provided on the bottom wall 31 of the clutch housing 30. The input gear 35 is fixed to the bottom wall 31 by rivets 35B via a torque damper 35A. The input gear 35 meshes with a drive gear (not shown) that rotates due to the rotational drive of the engine's input shaft. The input gear 35 rotates independently of the output shaft 15 and integrally with the clutch housing 30.

[0018] The input-side rotating plate 20 is rotationally driven by the rotational drive of the input shaft. As shown in Figure 1, the input-side rotating plate 20 is held on the inner circumferential surface of the side wall 33 of the clutch housing 30. The input-side rotating plate 20 is held by engaging with a notch 30C formed in the side wall 33 of the clutch housing 30. The input-side rotating plate 20 is provided so as to be displaceable along the axial direction (i.e., direction D) of the clutch housing 30. The input-side rotating plate 20 is provided so as to be rotatable integrally with the clutch housing 30.

[0019] The input-side rotating plate 20 is a component that is pressed against the output-side rotating plate 22. The input-side rotating plate 20 is formed in an annular shape. The input-side rotating plate 20 is molded from aluminum die-cast. A friction material (not shown) consisting of multiple pieces of paper is attached to the front and back surfaces of the input-side rotating plate 20. Grooves several hundred micrometers deep are formed between the friction material to hold clutch oil.

[0020] As shown in Figure 1, the clutch center 40 is housed in the clutch housing 30. The clutch center 40 is positioned concentrically with the clutch housing 30. The clutch center 40 has a cylindrical body 42 and a center-side flange 68 extending radially outward from the outer peripheral edge of the body 42. The body 42 protrudes further than the center-side flange 68 in a second direction D2. The clutch center 40 holds a portion of the input-side rotating plate 20 and a plurality of output-side rotating plates 22 that are alternately arranged in direction D. The clutch center 40 rotates together with the output shaft 15.

[0021] As shown in Figure 2, the main body 42 includes an output shaft holding portion 50 provided in the center of the main body 42, a center-side outer peripheral wall 45 located radially outward from the output shaft holding portion 50, and a plurality of center-side cam portions 60 connected to the output shaft holding portion 50 and the center-side outer peripheral wall 45.

[0022] As shown in Figures 2 and 3, the center flange 68 extends radially outward from the outer peripheral edge of the main body 42. The center flange 68 is located radially outward from the center cam portion 60. The center flange 68, together with the pressure flange 98 of the pressure plate 70 (described later), clamps the input rotating plate 20 and the output rotating plate 22. The center flange 68 is provided so as to be able to press against the input rotating plate 20 and the output rotating plate 22. The center flange 68 is a member that applies pressing force to the input rotating plate 20 and the output rotating plate 22.

[0023] As shown in Figure 2, the output shaft holder 50 is formed in a cylindrical shape. The output shaft holder 50 extends in direction D. The end of the output shaft holder 50 on the second direction D2 side is located on the second direction D2 side of the center side cam portion 60. An insertion hole 51 is formed through the output shaft holder 50 into which the output shaft 15 is inserted and spline fitted. Multiple spline grooves are formed along the axial direction on the inner circumferential surface 50A of the output shaft holder 50 that forms the insertion hole 51. The output shaft 15 is connected to the output shaft holder 50.

[0024] As shown in Figures 2 and 3, the center-side outer peripheral wall 45 is formed in an annular shape extending in direction D. A center-side spline fitting portion 46 is provided on the outer peripheral surface 45A of the center-side outer peripheral wall 45. The center-side 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 45A of the center-side outer peripheral wall 45, and a plurality of center-side spline grooves 48 formed between adjacent center-side fitting teeth 47 and extending in the axial direction of the clutch center 40. The center-side fitting teeth 47 hold the output-side rotating plate 22. The plurality of center-side fitting teeth 47 are arranged in the circumferential direction S. The plurality of center-side fitting teeth 47 are formed at equal intervals in the circumferential direction S. The plurality of 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 45A of the center-side outer circumferential wall 45. When viewed from the axial direction of the output shaft 15, the center-side fitting teeth 47 are formed from both side surfaces 47S in the circumferential direction S and a top surface 47Q that connects the radially outward ends of both side surfaces 47S. Multiple center-side spline grooves 48 are arranged in the circumferential direction S. Multiple center-side spline grooves 48 are formed at equal intervals in the circumferential direction S. Multiple center-side spline grooves 48 are formed to have the same shape. When viewed from the axial direction of the output shaft 15, the center-side spline grooves 48 are formed from the side surfaces 47S in the circumferential direction S of adjacent center-side fitting teeth 47 and the outer circumferential surface 45A of the center-side outer circumferential wall 45. The center-side outer circumferential wall 45 is provided with an oil flow hole 45F that penetrates radially. The oil flow hole 45F communicates with the center spline groove 48.

[0025] As shown in Figures 2 and 3, the clutch center 40 is provided with a plurality of center-side protrusions 41. The center-side protrusions 41 are provided at the end 47D2 of the center-side fitting teeth 47 in the second direction D2. The center-side protrusions 41 extend in the second direction D2 from the end 47D2 in the second direction D2. The center-side protrusions 41 and the center-side fitting teeth 47 are formed integrally. The plurality of center-side protrusions 41 are arranged in the circumferential direction S. The plurality of center-side protrusions 41 are formed at equal intervals in the circumferential direction S. The plurality of center-side protrusions 41 are formed in the same shape. Here, the center-side protrusions 41 include, for example, a first center-side protrusion 41A and a second center-side protrusion 41B. The length in direction D of the first center-side protrusion 41A and the length in direction D of the second center-side protrusion 41B are the same. Furthermore, the length in direction D of the first center-side projection 41A and the length in direction D of the second center-side projection 41B may be different. Also, although the clutch center 40 has three center-side projections 41, it may have two center-side projections 41, four or more center-side projections 41, or one center-side projection 41.

[0026] The output-side rotating plate 22 is held by the center-side spline fitting portion 46 of the clutch center 40 and the pressure-side spline fitting portion 76 of the pressure plate 70, which will be described later. A portion of the output-side rotating plate 22 is held by spline fitting to the center-side fitting teeth 47 and center-side spline groove 48 of the clutch center 40. Another portion of the output-side rotating plate 22 is held by spline fitting to the pressure-side fitting teeth 77 (see Figures 6 and 7) and pressure-side spline groove 78 (see Figures 6 and 7) 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.

[0027] The output-side rotating plate 22 is a component that is pressed against the input-side rotating plate 20. The output-side rotating plate 22 is formed in an annular shape. The output-side rotating plate 22 is formed by punching out an annular shape from a thin sheet material made of SPCC material. The friction material provided on the input-side rotating plate 20 may be provided on the output-side rotating plate 22 instead of the input-side rotating plate 20, or it may be provided on both the input-side rotating plate 20 and the output-side rotating plate 22.

[0028] The center-side cam portion 60 is formed in a trapezoidal shape and has a cam surface consisting of an inclined surface that constitutes an assist & slipper (registered trademark) mechanism that generates 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 slipper torque, which is a force that separates the input-side rotating plate 20 and the output-side rotating plate 22 early and transitions to a half-clutch state. The half-clutch state is a state between the clutch being engaged (i.e., the input-side rotating plate 20 and the output-side rotating plate 22 are pressed against each other) and the clutch being disengaged (i.e., the input-side rotating plate 20 and the output-side rotating plate 22 are separated from each other, and there is a gap between the input-side rotating plate 20 and the output-side rotating plate 22). The center-side cam portion 60 is formed on the main body 42. The end of the center-side cam portion 60 on the second direction D2 side is located on the second direction D2 side of the center-side outer peripheral wall 45. The center-side cam portions 60 are arranged at equal intervals in the circumferential direction S of the clutch center 40. In this embodiment, the clutch center 40 has three center-side cam portions 60, but the number of center-side cam portions 60 is not limited to three.

[0029] As shown in Figure 2, the center-side cam portion 60 is located radially outward of the output shaft holding portion 50. The center-side cam portion 60 has a center-side assist cam surface 60A (see also Figures 4 and 5) and a center-side slipper cam surface 60S. The center-side assist cam surface 60A is configured to generate a force (here, a first direction D1) in the direction from the pressure plate 70 toward the clutch center 40 in order to increase the pressing force (compression force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the clutch center 40 rotates relative to the pressure plate 70, such as when accelerating. In this embodiment, when the above force is generated, the position of the pressure plate 70 relative to the clutch center 40 does not change, and the pressure plate 70 does not need to physically approach the clutch center 40. However, the pressure plate 70 may be physically displaced relative to the clutch center 40. The center-side slipper cam surface 60S is configured to separate the pressure plate 70 from the clutch center 40 in order to reduce the pressing force (contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the clutch center 40 rotates relative to the pressure plate 70, such as when decelerating. In adjacent center-side cam portions 60 with respect to 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 arranged facing each other in the circumferential direction S.

[0030] As shown in Figures 4 and 5, the center-side cam portion 60 has a first corner portion 61 and a second corner portion 62. The first corner portion 61 defines the opening end of the center-side cam hole 43H on the first direction D1 side and is located on one side of the center-side cam hole 43H with respect to the circumferential direction S of the clutch center 40 (here, on the first circumferential direction S1 side). The first corner portion 61 is located on the center-side assist cam surface 60A side. The first corner portion 61 has a so-called R-chamfered shape with a rounded corner. The second corner portion 62 defines the opening end of the center-side cam hole 43H on the first direction D1 side and is located on the other side of the center-side cam hole 43H with respect to the circumferential direction S of the clutch center 40 (here, on the second circumferential direction S2 side). The second corner portion 62 is located on the center-side slipper cam surface 60S side. The second corner portion 62 has a so-called pin-corner shape with a pointed tip.

[0031] As shown in Figures 3 and 5, the clutch center 40 has a center-side cam hole 43H that penetrates a part of the main body 42. The center-side cam hole 43H penetrates the main body 42 in direction D. The center-side cam hole 43H extends from the radially outer portion of the output shaft holding portion 50 to the center-side outer peripheral wall 45. The center-side cam hole 43H is formed between the center-side assist cam surface 60A and the center-side slipper cam surface 60S of adjacent center-side cam portions 60. The center-side cam hole 43H has a first portion 43H1 located on the center-side assist cam surface 60A side and a second portion 43H2 located on the center-side slipper cam surface 60S side. The radial length L1 of the first portion 43H1 is longer than the radial length L2 of the second portion 43H2. The boss portion 84 (see Figure 1), which will be described later, of the pressure plate 70 is inserted into the center-side cam hole 43H. When viewed from the axial direction of the clutch center 40 (i.e., the axial direction of the output shaft 15), the center-side assist cam surface 60A and a portion of the center-side cam hole 43H overlap.

[0032] As shown in Figures 2 to 5, the clutch center 40 is provided with an inner diameter step portion 65. The inner diameter step portion 65 is formed on the radially outer surface 50J (see Figure 2) of the output shaft holding portion 50. The inner diameter step portion 65 extends in direction D. The inner diameter step portion 65 partitions a part of the center side cam hole 43H. When viewed from the axial direction of the output shaft 15, the portion 65S2 of the inner diameter step portion 65 located on the second circumferential direction S2 side is located radially outward than the portion 65S1 located on the first circumferential direction S1 side.

[0033] As shown in Figures 2 to 5, the clutch center 40 is provided with an outer diameter step portion 66. The outer diameter step portion 66 is formed on the radially inner surface 45P (see Figure 4) of the center-side outer peripheral wall 45. The outer diameter step portion 66 extends in direction D. The outer diameter step portion 66 partitions a part of the center-side cam hole 43H. When viewed from the axial direction of the output shaft 15, the portion 66S2 of the outer diameter step portion 66 located on the second circumferential direction S2 side is located radially inward than the portion 66S1 located on the first circumferential direction S1 side.

[0034] As shown in Figures 4 and 5, the clutch center 40 is provided with a spring housing 54. The spring housing 54 is an example of a housing. The spring housing 54 is recessed from the first direction D1 to the second direction D2. The spring housing 54 is formed in the main body 42. More specifically, the spring housing 54 is formed in the center-side cam portion 60. The spring housing 54 houses the clutch spring 25 (see Figure 1). In this embodiment, the clutch center 40 is provided with three spring housings 54. The three spring housings 54 are arranged at equal intervals in the circumferential direction S of the clutch center 40. Note that the number of spring housings 54 is not limited to three. The spring housings 54 are located on the second circumferential direction S2 side of the center-side slipper cam surface 60S. The spring housings 54 are located on the first circumferential direction S1 side of the first corner portion 61. The spring housing portion 54 is located on the first circumferential direction S1 side of the center-side assist cam surface 60A. The spring housing portion 54 has a bottom wall portion 54A that contacts the end portion 25D2 of the clutch spring 25 in the second direction D2. The length of the center-side cam hole 43H in the circumferential direction S is longer than the length of the spring housing portion 54 in the circumferential direction S. As shown in Figure 5, the center-side projection portion 41 is located radially outward of the spring housing portion 54. The center-side projection portion 41 is located radially outward of the outer diameter end portion 54T of the spring housing portion 54.

[0035] As shown in Figure 1, the clutch spring 25 is housed in the spring housing 54. The clutch spring 25 biases the pressure plate 70 toward the clutch center 40 with respect to direction D (i.e., the first direction D1). The clutch spring 25 is, for example, a coil spring made by winding spring steel in a spiral shape.

[0036] As shown in Figures 4 and 5, the clutch center 40 is provided with a recess 99 formed in the center-side flange 68. The recess 99 is located radially outward from the spring housing 54. The recess 99 is recessed from a first direction D1 to a second direction D2. For example, the recess 99 is recessed by 0.1 mm or more and 0.5 mm or less from the surface on the first direction D1 side. The recess 99 may also be recessed by a value greater than 0 and less than 0.1 mm from the surface on the first direction D1 side. At least a portion of the center-side projection 41 is located radially between the spring housing 54 and the recess 99.

[0037] As shown in Figure 1, the clutch center 40 is provided with a biasing member 68S. The biasing member 68S is, for example, a disc spring. The biasing member 68S is provided on the center-side flange 68. The biasing member 68S is provided so as to be able to contact the output-side rotating plate 22 which is held by the center-side fitting teeth 47. The biasing member 68S is configured to dampen the assist force generated when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A (described later) come into contact, in order to suppress a rapid increase in the contact force between the input-side rotating plate 20 and the output-side rotating plate 22 caused by the assist force generated.

[0038] As shown in Figure 1, the pressure plate 70 is housed in the clutch housing 30. The pressure plate 70 is located between the clutch housing 30 and the clutch center 40. The pressure plate 70 is provided so as to be able to move toward and away from the clutch center 40. The pressure plate 70 is provided so as to be able to rotate relative to the clutch center 40. The pressure plate 70 is configured to be able to press against the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 70 is arranged concentrically with the clutch center 40 and the clutch housing 30. As shown in Figure 6, the pressure plate 70 has a cylindrical body 72 and a pressure side flange 98 that is connected to the outer peripheral edge of the body 72 on the second direction D2 side and extends radially outward. The body 72 protrudes further in the first direction D1 than the pressure side flange 98. The pressure plate 70 holds a portion of the multiple output side rotating plates 22 which are arranged alternately with the input side rotating plate 20.

[0039] As shown in Figures 6 and 7, the main body 72 comprises an annular base wall 73, a fitting hole 80 provided in the center of the base wall 73, a pressure-side outer peripheral wall 75 located radially outward from the base wall 73 and extending toward a first direction D1, and a plurality of pressure-side cam portions 90 connected to the base wall 73 and the pressure-side outer peripheral wall 75.

[0040] As shown in Figures 6 and 7, the pressure-side flange 98 extends radially outward from the outer peripheral edge of the main body 72. The pressure-side flange 98 is located radially outward from the pressure-side cam portion 90. The pressure-side flange 98, together with the center-side flange 68 of the clutch center 40, clamps the input-side rotating plate 20 and the output-side rotating plate 22. The pressure-side flange 98 is provided so as to be able to press against the input-side rotating plate 20 and the output-side rotating plate 22. The pressure-side flange 98 is a member that applies pressing force to the input-side rotating plate 20 and the output-side rotating plate 22.

[0041] As shown in Figures 6 and 7, the fitting hole 80 is formed in the center of the main body 72. The fitting hole 80 penetrates the base wall 73 in direction D. The output shaft holding portion 50 (see Figure 2) of the clutch center 40 is inserted into the fitting hole 80. The fitting hole 80 is externally fitted onto the output shaft holding portion 50.

[0042] As shown in Figures 6 and 7, the pressure-side outer peripheral wall 75 is formed in an annular shape extending in direction D. A pressure-side spline fitting portion 76 is provided on the outer peripheral surface 75A of the pressure-side outer peripheral wall 75. The pressure-side spline fitting portion 76 has a plurality of pressure-side fitting teeth 77 that extend in the axial direction of the pressure plate 70 along the outer peripheral surface 75A of the pressure-side outer peripheral wall 75, and a plurality of pressure-side spline grooves 78 formed between adjacent pressure-side fitting teeth 77 and extending in the axial direction of the pressure plate 70. The pressure-side fitting teeth 77 hold the output-side rotating plate 22. The plurality of pressure-side fitting teeth 77 are arranged in the circumferential direction S. The plurality of pressure-side fitting teeth 77 are formed in the same shape. The pressure-side fitting teeth 77 protrude radially outward from the outer peripheral surface 75A of the pressure-side outer peripheral wall 75. The pressure-side fitting teeth 77 are formed from both circumferential side surfaces 77S and a top surface 77Q that connects the radially outer ends of both side surfaces 77S when viewed from the axial direction of the output shaft 15. In this embodiment, the pressure-side fitting teeth 77 and the center-side fitting teeth 47 have the same outer shape when viewed from the axial direction of the output shaft 15. Multiple pressure-side spline grooves 78 are arranged in the circumferential direction S. When viewed from the axial direction of the output shaft 15, the pressure-side spline grooves 78 are formed from the circumferential side surfaces 77S of adjacent pressure-side fitting teeth 77 and the outer surface 75A of the pressure-side outer peripheral wall 75. Multiple pressure-side spline grooves 78 include a first pressure-side spline groove 78A with a longer length in the circumferential direction S and a second pressure-side spline groove 78B with a shorter length in the circumferential direction S.

[0043] The pressure-side cam portion 90 is formed in a trapezoidal shape and has a cam surface consisting of an inclined surface that slides against the center-side cam portion 60 to generate assist torque or slipper torque, forming an assist & slipper (registered trademark) mechanism. The pressure-side cam portion 90 is formed to protrude in the first direction D1 from the pressure-side flange 98. As shown in Figure 7, the pressure-side cam portions 90 are arranged at equal intervals in the circumferential direction S of the pressure plate 70. In this embodiment, the pressure plate 70 has three pressure-side cam portions 90, but the number of pressure-side cam portions 90 is not limited to three.

[0044] As shown in FIG. 6, the pressure-side cam portion 90 is located on the outer side in the radial direction of the fitting hole 80. The pressure-side cam portion 90 has a pressure-side assist cam surface 90A (see also FIGS. 8 and 9) and a pressure-side slipper cam surface 90S. The pressure-side assist cam surface 90A is configured to be able to contact the center-side assist cam surface 60A. The pressure-side assist cam surface 90A is configured to generate a force in the direction from the pressure plate 70 toward the clutch center 40 in order to increase the pressing force (contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the pressure plate 70 rotates relative to the clutch center 40, such as when accelerating. The pressure-side slipper cam surface 90S is configured to be able to contact the center-side slipper cam surface 60S. The pressure-side slipper cam surface 90S is configured to separate the pressure plate 70 from the clutch center 40 in order to decrease the pressing force (contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the pressure plate 70 rotates relative to the clutch center 40, such as when decelerating. 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 arranged to face each other in the circumferential direction S.

[0045] Here, the actions 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, as shown in FIG. 10A, a rotational force in the first circumferential direction S1 is applied to the pressure plate 70. For this reason, due to the actions of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, a force in the first direction D1 is generated on the pressure plate 70. Thereby, the contact force between the input-side rotating plate 20 and the output-side rotating plate 22 is increased.

[0046] On the other hand, when the rotational speed of the output shaft 15 exceeds the rotational speeds of the input gear 35 and the clutch housing 30 and back torque occurs, as shown in FIG. 10B, a rotational force in the first circumferential direction S1 is applied to the clutch center 40. For this reason, due to the actions of the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S, the pressure plate 70 is moved 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. Thereby, problems with respect to the engine and the transmission due to back torque can be avoided.

[0047] As shown in FIGS. 7 and 9, the pressure plate 70 has a pressure-side cam hole 73H that penetrates a part of the base wall 73. The pressure-side cam hole 73H penetrates the base wall 73 in the direction D. The pressure-side cam hole 73H is located radially outside the fitting hole 80. The pressure-side cam hole 73H extends from the side of the fitting hole 80 to the pressure-side outer peripheral wall 75. The pressure-side cam hole 73H is formed to penetrate between adjacent pressure-side cam portions 90. The pressure-side cam hole 73H is formed to penetrate between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S of adjacent pressure-side cam portions 90. When viewed from the axial direction of the pressure plate 70, a part of the pressure-side assist cam surface 90A overlaps with the pressure-side cam hole 73H.

[0048] As shown in FIGS. 6 and 7, the pressure plate 70 includes a plurality (three in this embodiment) of boss portions 84. The plurality of boss portions 84 are arranged at equal intervals in the circumferential direction S. The boss portion 84 is formed in a cylindrical shape. The boss portion 84 is located radially outside the fitting hole 80. The boss portion 84 extends from the base wall 73 in the first direction D1. The boss portion 84 is provided on the pressure-side cam portion 90. The boss portion 84 is located between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S with respect to the circumferential direction S. As shown in FIG. 1, the boss portion 84 is inserted into the center-side cam hole 43H. A screw hole 84H into which a bolt 28 is inserted is formed in the boss portion 84. The screw hole 84H extends in the direction D.

[0049] As shown in Figure 1, the stopper plate 100 is provided so as to be in contact with the clutch center 40. The stopper plate 100 is a member that prevents the pressure plate 70 from moving away from the clutch center 40 by more than a predetermined distance in the second direction D2. The stopper plate 100 is a member that displaces the pressure plate 70 in direction D. The end 25D1 of the clutch spring 25 on the first direction D1 side contacts the stopper plate 100. The stopper plate 100 is fixed to the pressure plate 70 by bolts 28. The stopper plate 100 rotates integrally with the pressure plate 70. The stopper plate 100 moves in direction D relative to the clutch center 40 and rotates relative to the clutch center 40. The stopper plate 100 is actuated by a clutch release mechanism (not shown). Here, the clutch release mechanism is a mechanical device that operates in a vehicle such as a motorcycle equipped with a clutch device 10, by the operation of the driver's clutch lever (not shown). The clutch release mechanism may also be electrically operated by a servo motor or the like.

[0050] As shown in Figure 11, when viewed from the axial direction of the output shaft 15, at least a portion of the annular center-side annular portion 49 overlaps with the annular pressure-side annular portion 79. In this embodiment, the entire center-side annular portion 49 overlaps with the entire pressure-side annular portion 79. The center-side annular portion 49 is the portion radially enclosed by the center-side tip circle 49A, which passes through the tip 47T (i.e., top surface 47Q) of the center-side mating tooth 47 that is located radially outward, and the center-side root circle 49B, which passes through the root 47B of the center-side mating tooth 47 that is located radially inward. The root 47B is continuous with the outer circumferential surface 45A of the center-side outer circumferential wall 45 and is in the same position radially as the outer circumferential surface 45A. The pressure-side annular portion 79 is the portion radially enclosed by the pressure-side tip circle 79A, which passes through the outermost radially located tooth tip 77T (i.e., top surface 77Q) of the pressure-side mating teeth 77, and the pressure-side root circle 79B, which passes through the innermost radially located tooth root 77B of the pressure-side mating teeth 77, when viewed from the axial direction of the output shaft 15. The tooth root 77B is continuous with the outer circumferential surface 75A of the pressure-side outer circumferential wall 75 and is in the same position radially as the outer circumferential surface 75A. In Figure 11, the center-side mating teeth 47 and the center-side spline groove 48 are shown with dashed lines, and the pressure-side mating teeth 77 and the pressure-side spline groove 78 are shown with solid lines. The positional relationship between the pressure-side fitting teeth 77 and the center-side fitting teeth 47 when viewed from the axial direction of the output shaft 15, and the positional relationship between the pressure-side fitting teeth 77 and the center-side fitting teeth 47 when viewed from the radial direction of the output shaft 15, are the same as the positional relationship between the pressure-side fitting teeth 277 and the center-side fitting teeth 247 in the second embodiment described later (see Figures 26 to 29).

[0051] As shown in Figure 12, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, when viewed from the axial direction of the output shaft 15 (for example, when viewed from the first direction D1 to the second direction D2), a first gap 87 is provided on the second circumferential direction S2 side of the end portion 60AS2 of the center-side assist cam surface 60A, passing through the clutch center 40 and the pressure plate 70 in direction D and overlapping with the pressure-side cam hole 73H. The first gap 87 is partitioned by the end portion 60AS2, the pressure-side cam portion 90, and the pressure-side bottom wall portion 73B. As shown in Figures 6 and 7, the pressure-side bottom wall portion 73B is part of the base wall 73 and is located radially outward from the fitting hole 80. The pressure-side bottom wall portion 73B is located radially inward from the pressure-side cam portion 90. The bottom wall portion 73B on the pressure side is located on the second direction D2 side of the end portion 90D1 of the pressure side cam portion 90 in the first direction D1.

[0052] As shown in Figure 12, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, a recess 85 is formed by the clutch center 40 and the pressure plate 70, which is recessed in the second direction D2. The recess 85 is formed by the radially inner surface 90I of the pressure-side cam portion 90, the surface 73BD1 of the pressure-side bottom wall portion 73B on the first direction D1 side, and the radially outer surface 50J of the output shaft holding portion 50. The recess 85 is located on the second circumferential direction S2 side of the first gap 87.

[0053] As shown in Figure 12, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, a second gap 88 is provided on the radially outer side of the center-side assist cam surface 60A, which penetrates the clutch center 40 and the pressure plate 70 in direction D and overlaps with the pressure-side cam hole 73H. The second gap 88 is partitioned by the radially outer end 60AJ of the center-side assist cam surface 60A, the pressure-side cam portion 90, and the main body 42.

[0054] As shown in Figure 13, in at least a portion of the half-clutch state, when viewed from the radial direction of the output shaft 15, at least a portion of the center-side projection 41 overlaps with the pressure-side spline groove 78. In all of the half-clutch state, when viewed from the radial direction of the output shaft 15, at least a portion of the center-side projection 41 may overlap with the pressure-side spline groove 78. In the disengaged clutch state, when viewed from the radial direction of the output shaft 15, at least a portion of the center-side projection 41 may overlap with the pressure-side spline groove 78. In at least a portion (for example, all) of the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, when viewed from the radial direction of the output shaft 15, at least a portion of the center-side projection 41 may overlap with the pressure-side spline groove 78. When the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, at least a portion of the center-side projection 41 may overlap with the pressure-side spline groove 78 when viewed from the radial direction of the output shaft 15. When the clutch center 40 and the stopper plate 100 are in contact, at least a portion of the center-side projection 41 may overlap with the pressure-side spline groove 78 when viewed from the radial direction of the output shaft 15. The state in which a portion of the center-side projection 41 and the pressure-side spline groove 78 overlap, as shown in Figure 13, is just one example of each of the above states.

[0055] As shown in Figure 14, when the clutch center 40 and the stopper plate 100 are in contact, a gap 58 may be formed between the center-side projection 41 and the pressure plate 70 in direction D when viewed from the radial direction of the output shaft 15. The length 58L of the gap 58 in direction D is shorter than the length 22L of the output-side rotating plate 22 in direction D (see Figure 1). As shown in Figure 15, when the pressure plate 70 is closest to the clutch center 40, and the output-side rotating plate 22 held by the center-side fitting teeth 47 is defined as the outermost output-side rotating plate 22X, when the clutch center 40 and the stopper plate 100 are in contact, the surface 22XD1 of the outermost output-side rotating plate 22X on the first direction D1 side is located on the first direction D1 side than the end portion 41D2 of the center-side projection 41 on the second direction D2 side.

[0056] In the embodiment described above, the clutch center 40 is provided with a plurality of center-side protrusions 41, and for example, in at least a portion of the half-clutch state, at least a portion of the center-side protrusions 41 are configured to overlap with the pressure-side spline grooves 78 when viewed from the radial direction of the output shaft 15, but is not limited to this. As shown in Figure 16, for example, the pressure plate 70 is provided with a plurality of pressure-side protrusions 71, and for example, in at least a portion of the half-clutch state, at least a portion of the pressure-side protrusions 71 are configured to overlap with the center-side spline grooves 48 when viewed from the radial direction of the output shaft 15. The pressure-side protrusions 71 are provided at the end 77D1 of the pressure-side fitting teeth 77 in the first direction D1. The pressure-side protrusions 71 extend from the end 77D1 in the first direction D1 to the first direction D1. The positional relationship between the pressure-side projection 71 and the center-side spline groove 48 may be the same as the positional relationship between the center-side projection 41 and the pressure-side spline groove 78.

[0057] <Second Embodiment> Figure 17 is a cross-sectional view of a clutch device 210 according to the second embodiment. The clutch device 210 is installed in a vehicle such as a motorcycle. The clutch device 210 is a device that transmits or interrupts the rotational driving force of the input shaft (crankshaft) of the engine of a motorcycle to the output shaft 15. The clutch device 210 is a device for transmitting or interrupting the rotational driving force of the input shaft to the drive wheel (rear wheel) via the output shaft 15. The clutch device 210 is positioned between the engine and the transmission.

[0058] As shown in Figure 17, the clutch device 210 includes an output shaft 15, an input side rotating plate 20, an output side rotating plate 22, a clutch housing 30, a clutch center 240, a pressure plate 270, and a stopper plate 300.

[0059] As shown in Figure 17, the output shaft 15 is equipped with a push rod 16A in its hollow portion 15H and a push member 16B provided adjacent to the push rod 16A. The hollow portion 15H functions as a 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 slidably mounted inside the hollow portion 15H of the output shaft 15. One end of the push rod 16A (the left end in the figure) is connected to the clutch operating lever (not shown) of a motorcycle, and by operating the clutch operating lever, it slides inside the hollow portion 15H and presses the push member 16B in a second direction D2. A part of the push member 16B protrudes outward from the output shaft 15 (in this case, in the second direction D2) and is connected to a release bearing 18 provided on the pressure plate 270. The push rod 16A and the push member 16B are formed to be thinner than the inner diameter of the hollow portion 15H, ensuring that clutch oil can flow within the hollow portion 15H.

[0060] As shown in Figure 17, the clutch center 240 is housed in the clutch housing 30. The clutch center 240 is positioned concentrically with the clutch housing 30. As shown in Figure 18, the clutch center 240 has a cylindrical body 242 and a center-side flange 68 extending radially outward from the outer peripheral edge of the body 242. The body 242 protrudes further than the center-side flange 68 in a second direction D2. The clutch center 240 holds a portion of the input-side rotating plate 20 and a plurality of output-side rotating plates 22 that are alternately arranged in direction D. The clutch center 240 is rotationally driven together with the output shaft 15.

[0061] As shown in Figure 18, the main body 242 comprises an annular base wall 243, an output shaft holding portion 250 provided in the center of the base wall 243, a center-side outer peripheral wall 245 located radially outward from the base wall 243 and extending in a second direction D2, and a plurality of center-side cam portions 260 connected to the base wall 243 and the center-side outer peripheral wall 245.

[0062] As shown in Figure 18, the output shaft holder 250 is formed in a cylindrical shape. The output shaft holder 250 extends in direction D. The end of the output shaft holder 250 on the second direction D2 side is located on the first direction D1 side of the center side cam portion 260. The output shaft 15 is connected to the output shaft holder 250.

[0063] As shown in Figures 18 and 19, the center-side outer peripheral wall 245 is formed in an annular shape extending in direction D. A center-side spline fitting portion 246 is provided on the outer peripheral surface 245A of the center-side outer peripheral wall 245. The center-side spline fitting portion 246 has a plurality of center-side fitting teeth 247 extending in the axial direction of the clutch center 240 along the outer peripheral surface 245A of the center-side outer peripheral wall 245, and a plurality of center-side spline grooves 248 formed between adjacent center-side fitting teeth 247 and extending in the axial direction of the clutch center 240. The center-side fitting teeth 247 hold the output-side rotating plate 22. The plurality of center-side fitting teeth 247 are arranged in the circumferential direction S. The plurality of center-side fitting teeth 247 are formed in the same shape. The center-side fitting teeth 247 protrude radially outward from the outer circumferential surface 245A of the center-side outer circumferential wall 245. When viewed from the axial direction of the output shaft 15, the center-side fitting teeth 247 are formed from both side surfaces 247S in the circumferential direction S and a top surface 247Q that connects the radially outward ends of both side surfaces 247S. Multiple center-side spline grooves 248 are arranged in the circumferential direction S. Multiple center-side spline grooves 248 include a first center-side spline groove 248A with a longer length in the circumferential direction S and a second center-side spline groove 248B with a shorter length in the circumferential direction S. When viewed from the axial direction of the output shaft 15, the center-side spline grooves 248 are formed from the side surfaces 247S in the circumferential direction S of adjacent center-side fitting teeth 247 and the outer circumferential surface 245A of the center-side outer circumferential wall 245.

[0064] The center-side cam portion 260 is formed in a trapezoidal shape having a cam surface consisting of an inclined surface that constitutes the assist & slipper (registered trademark) mechanism. The center-side cam portion 260 is formed on the main body 242. The end of the center-side cam portion 260 on the second direction D2 side is flush with the end of the center-side outer peripheral wall 245 on the second direction D2 side. The center-side cam portions 260 are arranged at equal intervals in the circumferential direction S of the clutch center 240. In this embodiment, the clutch center 240 has three center-side cam portions 260, but the number of center-side cam portions 260 is not limited to three.

[0065] As shown in Figures 18 and 19, the center cam portion 260 is located radially outward from the output shaft holding portion 250. The center cam portion 260 has a center assist cam surface 60A (see also Figures 20 and 21) and a center slipper cam surface 60S. In adjacent center cam portions 260 with respect to the circumferential direction S, the center assist cam surface 60A of one center cam portion 260L and the center slipper cam surface 60S of the other center cam portion 260M are arranged facing each other in the circumferential direction S.

[0066] As shown in Figures 19 and 21, the clutch center 240 has a center-side cam hole 243H that penetrates a portion of the base wall 243. The center-side cam hole 243H penetrates the base wall 243 in direction D. The center-side cam hole 243H is located radially outward from the output shaft holding portion 250. The center-side cam hole 243H extends from the radially outward portion of the output shaft holding portion 250 to the center-side outer peripheral wall 245. The center-side cam hole 243H is formed through between adjacent center-side cam portions 260. The center-side cam hole 243H is formed through between the center-side assist cam surface 60A and the center-side slipper cam surface 60S of adjacent center-side cam portions 260. 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.

[0067] As shown in Figures 18 and 19, the clutch center 240 is provided with a plurality (three in this embodiment) of boss portions 84. The boss portions 84 are located radially outward from the output shaft holding portion 250. The boss portions 84 extend from the base wall 243 in a second direction D2. The boss portions 84 are provided on the center-side cam portion 260. As shown in Figure 17, the boss portions 84 are inserted into the pressure-side cam hole 273H.

[0068] As shown in Figure 17, the pressure plate 270 is housed in the clutch housing 30. The pressure plate 270 is located on the second direction D2 side of the clutch center 240. The pressure plate 270 is provided so as to be able to move toward or away from the clutch center 240. The pressure plate 270 is provided so as to be able to rotate relative to the clutch center 240. The pressure plate 270 is configured to be able to press against 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. As shown in Figure 22, the pressure plate 270 has a cylindrical body 272 and a pressure side flange 98 that is connected to the outer peripheral edge of the body 272 on the second direction D2 side and extends radially outward. The body 272 protrudes in the first direction D1 from the pressure side flange 98. The pressure plate 270 holds a portion of the multiple output-side rotating plates 22, which are arranged alternately with the input-side rotating plate 20.

[0069] As shown in Figures 22 and 23, the main body 272 comprises a cylindrical portion 281, a fitting hole 282 provided in the cylindrical portion 281, a pressure-side outer peripheral wall 275 located radially outward from the cylindrical portion 281 and extending in direction D, and a plurality of pressure-side cam portions 290 located radially outward from the cylindrical portion 281 and connected to the pressure-side outer peripheral wall 275.

[0070] As shown in Figures 22 and 23, the main body 272 has a through hole 298 that penetrates in direction D. The through hole 298 is located radially outward from the pressure-side outer peripheral wall 275. The through hole 298 is located radially outward from the pressure-side slipper cam surface 90S. The through hole 298 is located radially inward from the pressure-side flange 98. The through hole 298 is located between adjacent pressure-side fitting teeth 277.

[0071] As shown in Figures 22 and 23, the fitting hole 282 is provided at the opening end of the cylindrical portion 281 on the first direction D1 side. The output shaft holding portion 250 of the clutch center 240 is inserted into the fitting hole 282. The output shaft holding portion 250 is fitted into the fitting hole 282. The cylindrical portion 281 is located radially outward of the output shaft holding portion 250 when the pressure plate 270 is assembled to the clutch center 240.

[0072] As shown in Figures 22 and 23, the pressure-side outer peripheral wall 275 is formed in an annular shape extending in direction D. A pressure-side spline fitting portion 276 is provided on the outer peripheral surface 275A of the pressure-side outer peripheral wall 275. The pressure-side 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 pressure-side outer peripheral wall 275, and a plurality of pressure-side spline grooves 278 formed between adjacent pressure-side fitting teeth 277 and extending in the axial direction of the pressure plate 270. The pressure-side fitting teeth 277 hold the output-side rotating plate 22. The plurality of pressure-side fitting teeth 277 are arranged in the circumferential direction S. The plurality of pressure-side fitting teeth 277 are formed in the same shape. The pressure-side fitting teeth 277 protrude radially outward from the outer surface 275A of the pressure-side outer peripheral wall 275. When viewed from the axial direction of the output shaft 15, the pressure-side fitting teeth 277 are formed from both circumferential side surfaces 277S and a top surface 277Q that connects the radially outward ends of both side surfaces 277S. In this embodiment, when viewed from the axial direction of the output shaft 15, the pressure-side fitting teeth 277 and the center-side fitting teeth 247 have the same outer shape. Multiple pressure-side spline grooves 278 are arranged in the circumferential direction S. When viewed from the axial direction of the output shaft 15, the pressure-side spline grooves 278 are formed from the circumferential side surfaces 277S of adjacent pressure-side fitting teeth 277 and the outer surface 275A of the pressure-side outer peripheral wall 275.

[0073] As shown in Figures 22 and 23, the pressure plate 270 is provided with a plurality of pressure-side protrusions 271. The pressure-side protrusions 271 are provided at the end 277D1 of the pressure-side mating teeth 277 in the first direction D1. The pressure-side protrusions 271 extend from the end 277D1 in the first direction D1 in the first direction D1. The pressure-side protrusions 271 and the pressure-side mating teeth 277 are integrally formed. The plurality of pressure-side protrusions 271 are arranged in the circumferential direction S. The plurality of pressure-side protrusions 271 are formed at equal intervals in the circumferential direction S. The plurality of pressure-side protrusions 271 are formed in the same shape. Here, the pressure-side protrusions 271 include, for example, a first pressure-side protrusion 271A and a second pressure-side protrusion 271B. The length in direction D of the first pressure-side projection 271A and the length in direction D of the second pressure-side projection 271B are the same. However, the length in direction D of the first pressure-side projection 271A and the length in direction D of the second pressure-side projection 271B may be different.

[0074] The pressure-side cam portion 290 is formed in a trapezoidal shape having a cam surface consisting of an inclined surface that constitutes the assist & slipper (registered trademark) mechanism. The pressure-side cam portion 290 is formed to protrude in the first direction D1 from the pressure-side flange 98. The pressure-side cam portions 290 are arranged at equal intervals in the circumferential direction S of the pressure plate 270. In this embodiment, the pressure plate 270 has three pressure-side cam portions 290, but the number of pressure-side cam portions 290 is not limited to three.

[0075] As shown in Figures 22 and 23, the pressure-side cam portion 290 is located radially outward of the cylindrical portion 281. The pressure-side cam portion 290 has a pressure-side assist cam surface 90A (see also Figures 24 and 25) and a pressure-side slipper cam surface 90S. In adjacent pressure-side cam portions 290 with respect to the circumferential direction S, the pressure-side assist cam surface 90A of one pressure-side cam portion 290L and the pressure-side slipper cam surface 90S of the other pressure-side cam portion 290M are arranged opposite each other in the circumferential direction S.

[0076] As shown in Figures 24 and 25, the pressure-side cam portion 290 has a first corner portion 291 and a second corner portion 292. The first corner portion 291 defines the opening end of the pressure-side cam hole 273H on the second direction D2 side and is located on one side of the pressure-side cam hole 273H with respect to the circumferential direction S of the pressure plate 270 (here on the second circumferential direction S2 side). The first corner portion 291 is located on the pressure-side assist cam surface 90A side. The first corner portion 291 has a so-called R-chamfered shape with a rounded corner. The second corner portion 292 defines the opening end of the pressure-side cam hole 273H on the second direction D2 side and is located on the other side of the pressure-side cam hole 273H with respect to the circumferential direction S of the pressure plate 270 (here on the first circumferential direction S1 side). The second corner portion 292 is located on the pressure-side slipper cam surface 90S side. The second corner portion 292 has a so-called pin-corner shape with a pointed tip.

[0077] As shown in Figures 23 and 25, the pressure plate 270 has a pressure-side cam hole 273H that penetrates a portion of the main body 272. The pressure-side cam hole 273H penetrates the main body 272 in direction D. The pressure-side cam hole 273H is located radially outward from the fitting hole 282. The pressure-side cam hole 273H extends from the radially outward portion of the fitting hole 282 to the pressure-side outer peripheral wall 275. The pressure-side cam hole 273H is formed through between adjacent pressure-side cam portions 290. The pressure-side cam hole 273H is formed through between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S of adjacent pressure-side cam portions 290. The pressure-side cam hole 273H has a first portion 273H1 located on the pressure-side assist cam surface 90A side and a second portion 273H2 located on the pressure-side slipper cam surface 90S side. The radial length LH1 of the first portion 273H1 is longer than the radial length LH2 of the second portion 273H2. When viewed from the axial direction of the pressure plate 270 (i.e., the axial direction of the output shaft 15), the pressure-side assist cam surface 90A and a portion of the pressure-side cam hole 273H overlap.

[0078] As shown in Figures 22 to 25, the pressure plate 270 is provided with an inner diameter step portion 295. The inner diameter step portion 295 is formed on the radially outer surface 281J of the cylindrical portion 281. The inner diameter step portion 295 extends in direction D. The inner diameter step portion 295 partitions a part of the pressure side cam hole 273H. When viewed from the axial direction of the output shaft 15, the portion 295S1 of the inner diameter step portion 295 located on the first circumferential direction S1 side is located radially outward than the portion 295S2 located on the second circumferential direction S2 side.

[0079] As shown in Figures 22 to 25, the pressure plate 270 is provided with an outer diameter side stepped portion 296. The outer diameter side stepped portion 296 is formed on the radially inner surface of the pressure side outer peripheral wall 275. The outer diameter side stepped portion 296 extends in direction D. The outer diameter side stepped portion 296 partitions a part of the pressure side cam hole 273H. When viewed from the axial direction of the output shaft 15, the portion 296S1 of the outer diameter side stepped portion 296 located on the first circumferential direction S1 side is located radially inward than the portion 296S2 located on the second circumferential direction S2 side.

[0080] As shown in Figures 24 and 25, the pressure plate 270 is provided with a spring housing 54. The spring housing 54 is an example of a housing. The spring housing 54 is recessed from the second direction D2 toward the first direction D1. The spring housing 54 is formed in the main body 272. More specifically, the spring housing 54 is formed in the pressure-side cam portion 290. In this embodiment, the pressure plate 270 is provided with three spring housings 54. The three spring housings 54 are arranged at equal intervals in the circumferential direction S of the pressure plate 270. Note that the number of spring housings 54 is not limited to three. The spring housings 54 are located on the first circumferential direction S1 side of the pressure-side slipper cam surface 90S. The spring housings 54 are located on the second circumferential direction S2 side of the pressure-side assist cam surface 90A. The spring housing portion 54 is located on the second circumferential direction S2 side of the first corner portion 291. The bottom wall portion 54A of the spring housing portion 54 is in contact with the end portion 25D1 of the clutch spring 25 in the first direction D1. The length of the circumferential direction S of the pressure-side cam hole 273H is longer than the length of the circumferential direction S of the spring housing portion 54. The pressure-side projection portion 271 is located radially outward of the spring housing portion 54. The pressure-side projection portion 271 is located radially outward of the outer diameter side end portion 54T of the spring housing portion 54.

[0081] As shown in Figures 24 and 25, the pressure plate 270 is provided with a recess 299 formed in the pressure-side flange 98. The recess 299 is located radially outward from the spring housing 54. The recess 299 is recessed from the second direction D2 toward the first direction D1. For example, the recess 299 is recessed by 0.1 mm or more and 0.5 mm or less from the surface toward the second direction D2. The recess 299 may be recessed by a distance greater than 0 and less than 0.1 mm from the surface toward the second direction D2. At least a portion of the pressure-side projection 271 is located radially between the spring housing 54 and the recess 299.

[0082] As shown in Figure 17, the stopper plate 300 is provided so as to be in contact with the pressure plate 270. The stopper plate 300 is a member that prevents the pressure plate 270 from moving away from the clutch center 240 in the second direction D2 by more than a predetermined distance. The end 25D2 of the clutch spring 25 on the second direction D2 side contacts the stopper plate 300. The stopper plate 300 is fixed to the clutch center 240 by bolts 28. The stopper plate 300 rotates integrally with the clutch center 240.

[0083] As shown in Figure 26, when viewed from the axial direction of the output shaft 15, at least a portion of the annular center-side annular portion 249 overlaps with the annular pressure-side annular portion 279. In this embodiment, the entire center-side annular portion 249 overlaps with the entire pressure-side annular portion 279. The center-side annular portion 249 is the portion radially enclosed by the center-side tip circle 249A, which passes through the tip 247T (i.e., top surface 247Q) of the center-side mating tooth 247, and the center-side root circle 249B, which passes through the root 247B, which is the radially innermost of the center-side mating tooth 247, when viewed from the axial direction of the output shaft 15. The root 247B is continuous with the outer circumferential surface 245A of the center-side outer circumferential wall 245 and is in the same position radially as the outer circumferential surface 245A. The pressure-side annular portion 279 is the portion radially enclosed by the pressure-side tip circle 279A, which passes through the outermost radially located tooth tip 277T (i.e., top surface 277Q) of the pressure-side mating teeth 277, and the pressure-side root circle 279B, which passes through the innermost radially located tooth root 277B of the pressure-side mating teeth 277, when viewed from the axial direction of the output shaft 15. The tooth root 277B is continuous with the outer circumferential surface 275A of the pressure-side outer circumferential wall 275 and is in the same position radially as the outer circumferential surface 275A. In Figure 26, the center-side mating teeth 247 and the center-side spline groove 248 are shown with dashed lines, and the pressure-side mating teeth 277 and the pressure-side spline groove 278 are shown with solid lines.

[0084] As shown in Figures 27 and 28, when viewed from the axial direction of the output shaft 15, at least a portion of the pressure-side mating teeth 277 overlaps with the center-side mating teeth 247. When viewed from the axial direction of the output shaft 15, at least a portion of the tooth tip 277T of the pressure-side mating teeth 277 overlaps with the tooth tip 247T of the center-side mating teeth 247. In the example shown in Figure 27, when viewed from the axial direction of the output shaft 15, the entirety of one pressure-side mating tooth 277 overlaps with the entirety of one center-side mating tooth 247. When viewed from the axial direction of the output shaft 15, the entirety of the tooth tip 277T of one pressure-side mating tooth 277 overlaps with the entirety of the tooth tip 247T of one center-side mating tooth 247. When viewed from the axial direction of the output shaft 15, the center-side centerline 247L, which passes through the center 247C in the circumferential direction S of the center-side mating tooth 247 and the center 15C of the output shaft 15, coincides with the pressure-side centerline 277L, which passes through the center 277C in the circumferential direction S of the pressure-side mating tooth 277 and the center 15C of the output shaft 15. In the example shown in Figure 28, when viewed from the axial direction of the output shaft 15, a portion of one pressure-side mating tooth 277 coincides with a portion of one center-side mating tooth 247. When viewed from the axial direction of the output shaft 15, a portion of the tooth tip 277T of one pressure-side mating tooth 277 coincides with a portion of the tooth tip 247T of one center-side mating tooth 247. Furthermore, as shown in Figures 27 and 28, when viewed from the axial direction of the output shaft 15, at least a portion of the pressure-side spline groove 278 overlaps with the center-side spline groove 248. In the example shown in Figure 27, when viewed from the axial direction of the output shaft 15, the entirety of one pressure-side spline groove 278 overlaps with the entirety of one center-side spline groove 248. In the example shown in Figure 28, when viewed from the axial direction of the output shaft 15, a portion of one pressure-side spline groove 278 overlaps with a portion of one center-side spline groove 248.

[0085] As shown in Figure 29, when viewed from the axial direction of the output shaft 15, the pressure-side mating teeth 277 do not overlap with the center-side mating teeth 247. In the example shown in Figure 29, when viewed from the axial direction of the output shaft 15, the entire tip 277T of one pressure-side mating tooth 277 does not overlap with the entire tip 247T of one center-side mating tooth 247. Also, as shown in Figure 29, when viewed from the axial direction of the output shaft 15, parts of the multiple pressure-side spline grooves 278 do not overlap with the center-side spline grooves 248.

[0086] The positional relationship between the center-side fitting teeth 247 and the pressure-side fitting teeth 277 when viewed from the axial direction of the output shaft 15 differs depending on the relative position of the pressure plate 270 with respect to the clutch center 240. The positional relationship between the center-side fitting teeth 247 and the pressure-side fitting teeth 277 when viewed from the axial direction of the output shaft 15 may differ in each of the following cases, for example, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, when the clutch is partially engaged, when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, and when the pressure plate 270 is in contact with the stopper plate 300. When the positional relationship in Figure 27 is designated as positional relationship 1, the positional relationship in Figure 28 as positional relationship 2, and the positional relationship in Figure 29 as positional relationship 3, the positional relationship between the center-side fitting tooth 247 and the pressure-side fitting tooth 277, when viewed from the axial direction of the output shaft 15, can take the relationship shown in Figure 30. As shown in Figure 30, for example, in Example 1, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, it can be positional relationship 1 (Figure 27), when it is in a half-clutch state, it can be positional relationship 3 (Figure 29), when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, it can be positional relationship 2 (Figure 28), and when the pressure plate 270 is in contact with the stopper plate 300, it can be positional relationship 2 (Figure 28).

[0087] In at least a portion of the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15. In the state when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15. In all stages from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15.

[0088] In at least a portion of the operating state from the operating state in which the pressure plate 270 is closest to the clutch center 240 to the operating state in which the pressure plate 270 is furthest from the clutch center 240, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15. In all of the operating state from the operating state in which the pressure plate 270 is closest to the clutch center 240 to the operating state in which the pressure plate 270 is furthest from the clutch center 240, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15.

[0089] In at least a portion of the half-clutch state, when viewed from the axial direction of the output shaft 15, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247. In all of the half-clutch state, when viewed from the axial direction of the output shaft 15, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247.

[0090] In a portion of the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, when viewed from the axial direction of the output shaft 15, the center-side centerline 247L (see Figure 27), which passes through the center 247C in the circumferential direction S of the center-side fitting tooth 247 and the center 15C of the output shaft 15, may coincide with the pressure-side centerline 277L, which passes through the center 277C in the circumferential direction S of the pressure-side fitting tooth 277 and the center 15C of the output shaft 15. When the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, when viewed from the axial direction of the output shaft 15, the center-side centerline 247L may coincide with the pressure-side centerline 277L.

[0091] As shown in Figure 31, in at least a portion of the operating state from the operating state in which the pressure plate 270 is closest to the clutch center 240 to the operating state in which the pressure plate 270 is furthest from the clutch center 240, the center line 248C of the center-side spline groove 248 extending in the axial direction of the output shaft 15 and the center line 278C of the pressure-side spline groove 278 extending in the axial direction of the output shaft 15 are located on the same straight line when viewed from the radial direction of the output shaft 15, and at least a portion of the radially inner surface 248G of the center-side spline groove 248 (for example, the entire surface 248G) and at least a portion of the radially inner surface 278G of the pressure-side spline groove 278 (for example, the entire surface 278G) are located on the same plane when viewed from the axial direction of the output shaft 15 (see Figure 27).

[0092] As shown in Figure 32, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, when viewed from the axial direction of the output shaft 15 (for example, when viewed from the second direction D2 to the first direction D1), a first gap 287 is provided on the first circumferential direction S1 side of the end portion 90AS1 of the pressure-side assist cam surface 90A, passing through the clutch center 240 and the pressure plate 270 in direction D and overlapping with the center-side cam hole 243H. The first gap 287 is partitioned by the end portion 90AS1, the center-side cam portion 260, and the center-side bottom wall portion 243B. As shown in Figures 18 and 19, the center-side bottom wall portion 243B is part of the base wall 243 and is located radially outward from the output shaft holding portion 250 and radially inward from the center-side cam portion 260. The center-side bottom wall portion 243B is located on the first direction D1 side of the end portion 260D2 of the center-side cam portion 260 in the second direction D2.

[0093] As shown in Figure 32, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, a recess 285 is formed by the clutch center 240 and the pressure plate 270, which is recessed in the first direction D1. The recess 285 is formed by the radially inner surface 260I of the center-side cam portion 260, the second direction D2 side surface 243BD2 of the center-side bottom wall portion 243B, and the radially outer surface 281J of the cylindrical portion 281. The recess 285 is located on the first circumferential direction S1 side of the first gap 287.

[0094] As shown in Figure 32, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, a second gap 288 is provided on the radially outer side of the pressure-side assist cam surface 90A, passing through the clutch center 240 and the pressure plate 270 in direction D and overlapping with the center-side cam hole 243H when viewed from the axial direction of the output shaft 15. The second gap 288 is partitioned by the radially outer end 90AJ of the pressure-side assist cam surface 90A, the center-side cam portion 260, and the main body 272.

[0095] As shown in Figure 33, in at least a portion of the half-clutch state, when viewed from the radial direction of the output shaft 15, at least a portion of the pressure-side projection 271 overlaps with the center-side spline groove 248. In all of the half-clutch state, when viewed from the radial direction of the output shaft 15, at least a portion of the pressure-side projection 271 may overlap with the center-side spline groove 248. In the disengaged clutch state, when viewed from the radial direction of the output shaft 15, at least a portion of the pressure-side projection 271 may overlap with the center-side spline groove 248. In at least a portion (for example, all) of the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, when viewed from the radial direction of the output shaft 15, at least a portion of the pressure-side projection 271 may overlap with the center-side spline groove 248. When the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, at least a portion of the pressure-side projection 271 may overlap with the center-side spline groove 248 when viewed from the radial direction of the output shaft 15. When the pressure plate 270 and the stopper plate 300 are in contact (i.e., when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 with respect to direction D), at least a portion of the pressure-side projection 271 may overlap with the center-side spline groove 248 when viewed from the radial direction of the output shaft 15. Note that the state in which a portion of the pressure-side projection 271 and the center-side spline groove 248 overlap, as shown in Figure 33, may be just one example of the above states.

[0096] As shown in Figure 34, when the pressure plate 270 and the stopper plate 300 are in contact, a gap 258 may be formed between the pressure-side projection 271 and the clutch center 240 in direction D when viewed from the radial direction of the output shaft 15. The length 258L of the gap 258 in direction D is shorter than the length 22L of the output-side rotating plate 22 in direction D (see Figure 17). As shown in Figure 35, when the pressure plate 270 is closest to the clutch center 240, and the output side rotating plate 22 held by the pressure side projection 271 is designated as the outermost output side rotating plate 22X, the surface 22XD2 of the outermost output side rotating plate 22X on the second direction D2 side is located on the second direction D2 side than the end portion 271D1 of the pressure side projection 271 on the first direction D1 side.

[0097] In the embodiment described above, the pressure plate 270 is provided with a plurality of pressure-side protrusions 271, and for example, in at least a portion of the half-clutch state, at least a portion of the pressure-side protrusions 271 are configured to overlap with the center-side spline groove 248 when viewed from the radial direction of the output shaft 15, but is not limited to this. For example, the clutch center 240 is provided with a plurality of center-side protrusions 241, and as shown in Figure 36, for example, in at least a portion of the half-clutch state, at least a portion of the center-side protrusions 241 are configured to overlap with the pressure-side spline groove 278 when viewed from the radial direction of the output shaft 15. The center-side protrusions 241 are provided at the end 247D2 of the center-side fitting teeth 247 in the second direction D2. The center-side protrusions 241 extend from the end 247D2 in the second direction D2 in the second direction D2. The positional relationship between the center-side projection 241 and the pressure-side spline groove 278 may be the same as the positional relationship between the pressure-side projection 271 and the center-side spline groove 248.

[0098] As described above, according to the clutch device 210 of this embodiment, at least a portion of the pressure-side fitting teeth 277 overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15, from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact. According to the above embodiment, clutch oil accumulated between adjacent pressure-side fitting teeth 277 flows toward the center-side fitting teeth 247, or clutch oil accumulated between adjacent center-side fitting teeth 247 flows toward the pressure-side fitting teeth 277, thereby effectively supplying clutch oil to the center-side fitting teeth 247 and pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270. As a result, the output-side rotating plate 22, held by the pressure-side mating teeth 277 and the center-side mating teeth 247, can move smoothly in direction D.

[0099] In the clutch device 210 of this embodiment, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15, from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact. According to the above embodiment, clutch oil can be supplied more effectively to the center-side fitting teeth 247 and the pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and the pressure plate 270.

[0100] In the clutch device 210 of this embodiment, in a portion of the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, when viewed from the axial direction of the output shaft 15, the center-side centerline 247L passing through the center 247C in the circumferential direction S of the center-side fitting tooth 247 and the center 15C of the output shaft 15 may overlap with the pressure-side centerline 277L passing through the center 277C in the circumferential direction S of the pressure-side fitting tooth 277 and the center 15C of the output shaft 15. According to the above embodiment, clutch oil can be supplied more effectively to the center-side fitting tooth 247 and the pressure-side fitting tooth 277 that hold the output-side rotating plate 22 in the clutch center 240 and the pressure plate 270.

[0101] In the clutch device 210 of this embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15. According to the above embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, clutch oil can be supplied more effectively to the center-side fitting teeth 247 and the pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270.

[0102] In the clutch device 210 of this embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the center-side centerline 247L may overlap with the pressure-side centerline 277L when viewed from the axial direction of the output shaft 15. According to the above embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, clutch oil can be supplied more effectively to the center-side fitting teeth 247 and the pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270.

[0103] In the clutch device 210 of this embodiment, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15, from the operating state in which the pressure plate 270 is closest to the clutch center 240 to the operating state in which the pressure plate 270 is furthest from the clutch center 240. According to the above embodiment, clutch oil accumulated between adjacent pressure-side fitting teeth 277 flows toward the center-side fitting teeth 247, or clutch oil accumulated between adjacent center-side fitting teeth 247 flows toward the pressure-side fitting teeth 277, thereby effectively supplying clutch oil to the center-side fitting teeth 247 and pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270.

[0104] In the clutch device 210 of this embodiment, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15, from the operating state in which the pressure plate 270 is closest to the clutch center 240 to the operating state in which the pressure plate 270 is furthest from the clutch center 240. According to the above embodiment, clutch oil can be supplied more effectively to the center-side fitting teeth 247 and the pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270.

[0105] In the clutch device 210 of this embodiment, in at least a portion of the half-clutch state, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15. According to the above embodiment, clutch oil accumulated between adjacent pressure-side fitting teeth 277 flows toward the center-side fitting teeth 247, or clutch oil accumulated between adjacent center-side fitting teeth 247 flows toward the pressure-side fitting teeth 277, thereby effectively supplying clutch oil to the center-side fitting teeth 247 and pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270.

[0106] In the clutch device 210 of this embodiment, in all half-clutch states, at least a portion of the pressure-side fitting teeth 277 may overlap with the center-side fitting teeth 247 when viewed from the axial direction of the output shaft 15. According to the above embodiment, clutch oil can be supplied more effectively to the center-side fitting teeth 247 and the pressure-side fitting teeth 277 that hold the output-side rotating plate 22 in the clutch center 240 and pressure plate 270.

[0107] <Third Embodiment> In the first and second embodiments described above, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the center-side centerline 247L overlaps with the pressure-side centerline 277L when viewed from the axial direction of the output shaft 15, but is not limited to this. As shown in Figure 37, in the clutch device 210 according to the third embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the center-side centerline 247L and the pressure-side centerline 277L1 do not overlap when viewed from the axial direction of the output shaft 15. The pressure-side centerline 277L1 is the pressure-side centerline 277L when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact. The pressure-side centerline 277L1 is located on the second circumferential direction S2 side of the center-side centerline 247L. In Figure 37, the solid line indicates the position of the center-side fitting tooth 247, the dashed line indicates the position of the pressure-side fitting tooth 277 when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the dashed line indicates the position of the pressure-side fitting tooth 277 when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are beginning to make contact, and the dashed line indicates the position of the pressure-side fitting tooth 277 when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D (for example, when the pressure plate 270 and the stopper plate 300 are in contact).

[0108] As shown in Figure 38, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, a gap 259 is formed between the clutch center 240 and the pressure plate 270 in direction D. More specifically, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, a gap 259 is formed between the end 247D2 of the center-side fitting tooth 247 in the second direction D2 and the end 277D1 of the pressure-side fitting tooth 277 in the first direction D1 in direction D. The gap 259 is formed throughout the entire range from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D.

[0109] As shown in Figure 37, when the center slipper cam surface 60S and the pressure slipper cam surface 90S begin to make contact, the center centerline 247L and the pressure centerline 277L2 do not overlap when viewed from the axial direction of the output shaft 15. The pressure centerline 277L2 is the pressure centerline 277L when the center slipper cam surface 60S and the pressure slipper cam surface 90S begin to make contact. The pressure centerline 277L2 is located on the second circumferential direction S2 side of the center centerline 247L.

[0110] As shown in Figure 37, when the center slipper cam surface 60S and the pressure slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D, the center centerline 247L and the pressure centerline 277L3 do not coincide when viewed from the axial direction of the output shaft 15. The pressure centerline 277L3 is the pressure centerline 277L when the center slipper cam surface 60S and the pressure slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D. The pressure centerline 277L3 is located on the second circumferential direction S2 side of the center centerline 247L. As shown in Figure 34, when the center slipper cam surface 60S and the pressure side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 in direction D (for example, when the pressure plate 270 and the stopper plate 300 are in contact), the pressure side projection 271 and the center side fitting teeth 247 do not overlap when viewed from the radial direction.

[0111] As shown in Figure 38, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the center-side fitting teeth 247 and the pressure-side fitting teeth 277 are offset with respect to the circumferential direction S. Also, as shown in Figure 39, when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 with respect to direction D, the center-side fitting teeth 247 and the pressure-side fitting teeth 277 are offset with respect to the circumferential direction S. Therefore, as shown by arrow FL1 in Figures 38 and 39, the clutch oil flowing along the center-side outer peripheral wall 245 (for example, the center-side spline groove 248) toward the pressure-side fitting teeth 277 strikes the end of the pressure-side fitting teeth 277 (the end 277D1 on the first direction D1 side) and flows from the gap 259 between the pressure plate 270 and the clutch center 240 toward the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S. Furthermore, as shown by arrow FL2 in Figures 38 and 39, the clutch oil flowing along the pressure-side outer peripheral wall 275 (for example, the pressure-side spline groove 278) toward the center-side fitting teeth 247 strikes the end of the center-side fitting teeth 247 (the end 247D2 on the second direction D2 side) and flows from the gap 259 between the pressure plate 270 and the clutch center 240 toward the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S. Furthermore, since the circumferential distance S between the center-side centerline 247L and the pressure-side centerline 277L3 is longer than the circumferential distance S between the center-side centerline 247L and the pressure-side centerline 277L1, in Figure 39, more clutch oil comes into contact with the ends of the pressure-side fitting teeth 277 and the ends of the center-side fitting teeth 247 compared to Figure 38, and more clutch oil flows toward the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S.

[0112] As shown in Figure 37, from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S begin to come into contact, the center-side centerline 247L and the pressure-side centerline 277L do not coincide when viewed from the axial direction of the output shaft 15. From the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S begin to come into contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D, the center-side centerline 247L and the pressure-side centerline 277L do not coincide when viewed from the axial direction of the output shaft 15. From the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D, the center-side centerline 247L and the pressure-side centerline 277L do not coincide when viewed from the axial direction of the output shaft 15.

[0113] In the clutch device 210 of this embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the center-side centerline 247L and the pressure-side centerline 277L1 do not coincide when viewed from the axial direction of the output shaft 15. That is, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the center-side fitting teeth 247 and the pressure-side fitting teeth 277 are offset with respect to the circumferential direction S. For this reason, for example, the clutch oil flowing along the center-side outer peripheral wall 245 toward the pressure-side fitting teeth 277 hits the end of the pressure-side fitting teeth 277 and flows from the gap 259 between the pressure plate 270 and the clutch center 240 toward the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S. In this way, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, clutch oil can be effectively supplied to the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S.

[0114] According to the clutch device 210 of this embodiment, from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact, the center-side centerline 247L and the pressure-side centerline 277L do not overlap when viewed from the axial direction of the output shaft 15. As a result, clutch oil can be effectively supplied to the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S, and the center-side assist cam surface 60S and the pressure-side slipper cam surface 90S, from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact.

[0115] According to the clutch device 210 of this embodiment, when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 in direction D, the center-side centerline 247L and the pressure-side centerline 277L3 do not coincide when viewed from the axial direction of the output shaft 15. As a result, when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 in direction D, clutch oil can be effectively supplied to the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S.

[0116] In the clutch device 210 of this embodiment, when the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 in direction D, the pressure-side projection 271 and the center-side fitting teeth 247 do not overlap when viewed from the radial direction of the output shaft 15. That is, the pressure-side projection 271 and the center-side fitting teeth 247 are offset with respect to the circumferential direction S. Therefore, for example, the clutch oil flowing along the center-side outer peripheral wall 245 (for example, the center-side spline groove 248) toward the pressure-side projection 271 hits the end of the pressure-side projection 271 and flows from the gap 259 between the pressure plate 270 and the clutch center 240 toward the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S.

[0117] <Fourth Embodiment> As shown in Figure 40, in the clutch device 210 according to the fourth embodiment, in most states from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D, the center-side centerline 247L and the pressure-side centerline 277L do not overlap when viewed from the axial direction of the output shaft 15. The pressure-side centerline 277L1 is located on the first circumferential direction S1 side than the center-side centerline 247L. The pressure-side centerline 277L2 is located on the first circumferential direction S1 side than the center-side centerline 247L. The pressure-side centerline 277L3 is located on the second circumferential direction S2 side than the center-side centerline 247L. Furthermore, the clutch device 210 according to the fourth embodiment has the same configuration as the clutch device 210 according to the third embodiment, except that the pressure-side centerline 277L1 and the pressure-side centerline 277L2 are located on the first circumferential direction S1 side of the center-side centerline 247L. In addition, in the fourth embodiment, from the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S begin to come into contact, to the state in which the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S come into contact and the pressure plate 270 is furthest away from the clutch center 240 in direction D, the center-side centerline 247L and the pressure-side centerline 277L overlap when viewed from the axial direction of the output shaft 15.

[0118] In the clutch device 210 of this embodiment, when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are in contact, the pressure-side centerline 277L1 is located on the first circumferential direction S1 side than the center-side centerline 247L when viewed from the axial direction of the output shaft 15. When the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S are in contact and the pressure plate 270 is at its furthest distance from the clutch center 240 with respect to direction D, the pressure-side centerline 277L3 is located on the second circumferential direction S2 side than the center-side centerline 247L when viewed from the axial direction of the output shaft 15. In other words, the pressure-side fitting teeth 277 and the center-side fitting teeth 247 are offset from each other with respect to the circumferential direction S in most cases. Therefore, for example, the clutch oil flowing along the center-side outer peripheral wall 245 (for example, the center-side spline groove 248) toward the pressure-side projection 271 hits the end of the pressure-side projection 271 and flows from the gap 259 between the pressure plate 270 and the clutch center 240 toward the center-side assist cam surface 60A and the pressure-side assist cam surface 90A.

[0119] Preferred embodiments of the present invention have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms.

[0120] In the embodiments described above, the clutch centers 40, 240 and the pressure plates 70, 270 were configured to hold the output-side rotating plates 22, respectively, but the invention is not limited to this configuration. For example, the clutch centers 40, 240 may hold all of the output-side rotating plates 22, while the pressure plates 70, 270 may not hold any of the output-side rotating plates 22. Alternatively, the pressure plates 70, 270 may hold all of the output-side rotating plates 22, while the clutch centers 40, 240 may not hold any of the output-side rotating plates 22.

[0121] In the embodiments described above, the center-side cam portions 60 and 260 have a center-side assist cam surface 60A and a center-side slipper cam surface 60S, but they may have only one of them. Similarly, the pressure-side cam portions 90 and 290 have a pressure-side assist cam surface 90A and a pressure-side slipper cam surface 90S, but they may have only one of them. For example, the center-side cam portions 60 and 260 may have only a center-side assist cam surface 60A, and the pressure-side cam portions 90 and 290 may have only a pressure-side assist cam surface 90A. Alternatively, the center-side cam portions 60 and 260 may have only a center-side slipper cam surface 60S, and the pressure-side cam portions 90 and 290 may have only a pressure-side slipper cam surface 90S.

[0122] 60A Center-side assist cam surface 60S Center-side slipper cam surface 90A Pressure-side assist cam surface 90S Pressure-side slipper cam surface 210 Clutch device 240 Clutch center 245 Center-side outer peripheral wall 247 Center-side mating tooth 247T Tooth tip 247B Tooth root 247C Circumferential center 247L Center-side centerline 248 Center-side spline groove 249 Center-side annular section 249A Center-side tooth tip circle 249B Center-side tooth root circle 260 Center-side cam section 270 Pressure plate 275 Pressure-side outer peripheral wall 277 Pressure-side mating tooth 277T Tooth tip 277B Tooth root 277C Circumferential center 277L Pressure-side centerline 278 Pressure-side spline groove 279 Pressure-side annular portion 279A Pressure-side tooth tip circle 279B Pressure-side tooth root circle 290 Pressure-side cam portion

Claims

1. A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center housed in a clutch housing that holds a plurality of input-side rotating plates that are rotationally driven by the rotational drive of the input shaft, and which holds a portion of a plurality of output-side rotating plates arranged alternately with the input-side rotating plates, and which is rotationally driven together with the output shaft; and a pressure plate provided so as to be able to approach and move away from the clutch center, which holds a portion of the plurality of output-side rotating plates, and which can press the input-side rotating plates and the output-side rotating plates, wherein the clutch center comprises: an annular center-side outer peripheral wall extending in the direction of movement when the direction in which the pressure plate approaches and moves away from the clutch center is the direction of movement; and a plurality of center-side fitting teeth arranged in the circumferential direction that hold the output-side rotating plates and project radially outward from the outer peripheral surface of the center-side outer peripheral wall, The pressure plate comprises a plurality of center-side cam portions having a center-side assist cam surface that generates a force in the direction toward the clutch center from the pressure plate in order to increase the pressing force between the input-side rotating plate and the output-side rotating plate when rotated relative to the pressure plate, and a center-side slipper cam surface that separates the pressure plate from the clutch center in order to decrease the pressing force between the input-side rotating plate and the output-side rotating plate, wherein the pressure plate comprises an annular pressure-side outer peripheral wall extending in the direction of movement, and a plurality of pressure-side fitting teeth arranged in the circumferential direction that hold the output-side rotating plate and protrude radially outward from the outer peripheral surface of the pressure-side outer peripheral wall, The device comprises a plurality of pressure-side cam portions having a pressure-side assist cam surface that generates a force in the direction toward the clutch center from the pressure plate in order to increase the pressing force between the input-side rotating plate and the output-side rotating plate when rotated relative to the clutch center, and a pressure-side slipper cam surface that separates the pressure plate from the clutch center in order to decrease the pressing force between the input-side rotating plate and the output-side rotating plate,When viewed from the axial direction of the output shaft, at least a portion of the annular center-side ring portion, which is radially enclosed by the center-side tip circle passing through the tip of the tooth located most radially outward among the center-side mating teeth and the center-side root circle passing through the root of the tooth located most radially inward among the center-side mating teeth, overlaps with the annular pressure-side ring portion, which is radially enclosed by the pressure-side tip circle passing through the tip of the tooth located most radially outward among the pressure-side mating teeth and the pressure-side root circle passing through the root of the tooth located most radially inward among the pressure-side mating teeth, and in a state where the center-side assist cam surface and the pressure-side assist cam surface are in contact, a gap is formed between the clutch center and the pressure plate with respect to the direction of movement. A clutch device in which, when the center assist cam surface and the pressure assist cam surface are in contact, the center center line passing through the circumferential center of the center fitting tooth and the center of the output shaft does not coincide with the pressure center line passing through the circumferential center of the pressure fitting tooth and the center of the output shaft when viewed from the axial direction of the output shaft.

2. The clutch device according to claim 1, wherein, in all stages from the state in which the center assist cam surface and the pressure assist cam surface are in contact to the state in which the center slipper cam surface and the pressure slipper cam surface begin to come into contact, the center center line and the pressure center line do not coincide when viewed from the axial direction of the output shaft.

3. The clutch device according to claim 1, wherein, when the center slipper cam surface and the pressure slipper cam surface are in contact and the pressure plate is at its furthest distance from the clutch center with respect to the direction of movement, the center center line and the pressure center line do not coincide when viewed from the axial direction of the output shaft.

4. The clutch device according to claim 1, wherein, with respect to the circumferential direction, the direction from one to the other is defined as the first circumferential direction, and the direction from the other to the one is defined as the second circumferential direction, the clutch center and the pressure plate are configured to rotate in the first circumferential direction during normal operation, the pressure side centerline is located on the first circumferential side of the center side centerline when viewed from the axial direction of the output shaft in a state in which the center side assist cam surface and the pressure side assist cam surface are in contact, and the pressure plate is at its furthest distance from the clutch center with respect to the direction of movement, the pressure side centerline is located on the second circumferential side of the center side centerline when viewed from the axial direction of the output shaft.

5. The clutch device according to claim 1, wherein, when the direction in which the pressure plate approaches the clutch center is defined as the first direction and the direction in which the pressure plate moves away from the clutch center is defined as the second direction, the end of the pressure-side fitting tooth in the first direction is provided with a pressure-side projection extending in the first direction, and when the center-side slipper cam surface and the pressure-side slipper cam surface are in contact and the pressure plate is at its furthest distance from the clutch center in the direction of movement, the pressure-side projection and the center-side fitting tooth do not overlap when viewed from the radial direction.

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