Clutch device

Abstract

To provide a clutch device, in which a clutch is restrained from being suddenly connected.SOLUTION: A clutch device 10 comprises a clutch spring 25 energizing a pressure plate 70 in a first direction D1, and a stopper plate 100 fixed to a clutch center 40. An axial line 25L of the clutch spring 25 is inclined to a pressure side slipper cam face side 90S as it goes from an end 25D1 in the first direction D1 of the clutch spring 25 toward an end 25D2 in a second direction D2 while a center side assist cam face 60A is in contact with a pressure side assist cam face 90A, when seen from a cross section in a peripheral direction S of the clutch center 40 and the pressure plate 70, and is parallel to a straight line extending in a direction D under a condition that the center side assist cam face 60A and the pressure side assist cam face 90A are isolated furthest from each other in a rotation direction S.SELECTED DRAWING: Figure 10B

Description

[Technical Field]

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

[0002] Conventionally, vehicles such as motorcycles have been equipped with clutch devices. For example, Patent Document 1 discloses a clutch device including a clutch center that holds an output rotating plate, a pressure plate that is movable toward and away from the clutch center, and a clutch spring that urges the pressure plate toward the clutch center. The clutch spring is housed in a housing formed in the pressure plate. One end of the clutch spring contacts the pressure plate, and the other end of the clutch spring contacts a stopper plate fixed to the clutch center. Furthermore, the clutch center and pressure plate of the clutch device disclosed in Patent Document 1 each include a center-side assist cam surface and a pressure-side assist cam surface that generate a force from the pressure plate toward the clutch center when the engine's rotational driving force is ready to be transmitted to the output shaft, thereby increasing the pressing force between the input rotating plate and the output rotating plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6894792 Summary of the Invention [Problem to be solved by the invention]

[0004] When the clutch transitions from an engaged state to a disengaged state, i.e., when the center-side assist cam surface and the pressure-side assist cam surface transition from a contacting state to a separated state, the pressure plate moves in a direction away from the clutch center while rotating relative to the clutch center in the circumferential direction. Therefore, a restoring force acting from the clutch spring housed in the housing toward the pressure-side assist cam surface (i.e., a restoring force that attempts to return the center-side assist cam surface and the pressure-side assist cam surface to a contacting state) can be generated in the clutch spring housed in the housing. If this restoring force is too large, the center-side assist cam surface and the pressure-side assist cam surface may suddenly come into contact with each other when the clutch transitions from a disengaged state to an engaged state, potentially resulting in a sudden engagement of the clutch.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a clutch device in which sudden engagement of the clutch is suppressed. [Means for solving the problem]

[0006] 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 that rotates together with the output shaft; a pressure plate that is capable of moving toward or away from the clutch center and rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plates, and that can press the input side rotating plates and the output side rotating plates; a clutch spring that urges the pressure plate in a first direction, where a direction in which the pressure plate approaches the clutch center is defined as a first direction, and a direction in which the pressure plate moves away from the clutch center is defined as a second direction; and a stopper plate that is fixed to the clutch center and that prevents the pressure plate from moving away from the clutch center in the second direction by more than a predetermined distance, wherein an end of the clutch spring in the first direction comes into contact with the pressure plate, and a stopper plate that prevents the pressure plate from moving away from the clutch center in the second direction by more than a predetermined distance, and the pressure plate has a pressure-side assist cam surface that is configured to be able to come into contact with the center-side assist cam surface when it rotates relative to the clutch center and that generates a force in a direction from the pressure plate toward the clutch center to increase the pressing force between the input side rotating plate and the output side rotating plate, and an accommodating portion that is arranged alongside the pressure-side assist cam surface in the rotational direction of the pressure plate and that accommodates the clutch spring, and has reduction means that reduces the restoring force of the clutch spring in the direction from the clutch spring toward the pressure-side assist cam surface during the period when the center-side assist cam surface and the pressure-side assist cam surface move from being spaced apart in the rotational direction to approaching and contacting each other.

[0007] In the clutch device according to the present invention, the reduction means reduces the restoring force of the clutch spring in the direction from the clutch spring toward the pressure-side assist cam surface during the period from when the center-side assist cam surface and the pressure-side assist cam surface are spaced apart in the rotational direction until they approach each other and come into contact. In this way, the reduction means reduces the restoring force that may be generated in the clutch spring, thereby preventing the center-side assist cam surface and the pressure-side assist cam surface from suddenly coming into contact with each other due to the restoring force. In other words, the reduction means can prevent the clutch from suddenly engaging.

[0008] Another clutch device according to the present invention is a clutch device that transmits or cuts off the rotational drive force of an input shaft to an output shaft, and includes: a clutch center that is accommodated in a clutch housing that holds a plurality of input side rotating plates that are rotationally driven by the rotational drive of the input shaft and that is rotationally driven together with the output shaft; a pressure plate that is provided to be able to approach or move away from the clutch center and to be rotatable relative to the clutch center, that holds a plurality of output side rotating plates that are arranged alternately with the input side rotating plates, and that is capable of pressing the input side rotating plates and the output side rotating plates; a clutch spring that urges the pressure plate in the first direction, when a direction in which the pressure plate approaches the clutch center is defined as a first direction and a direction in which the pressure plate moves away from the clutch center is defined as a second direction; and a lifter plate that is fixed to the pressure plate and that prevents the pressure plate from moving away from the clutch center in the second direction by more than a predetermined distance, wherein an end of the clutch spring in the first direction comes into contact with the lifter plate, and The end in the second direction contacts the clutch center, and the clutch center has a center-side assist cam surface that generates a force in a direction from the pressure plate toward the clutch center to increase the pressing force between the input side rotating plate and the output side rotating plate when the clutch center rotates relative to the pressure plate, and an accommodating portion that is arranged alongside the center-side assist cam surface in the rotational direction of the clutch center and that accommodates the clutch spring, and the pressure plate has a pressure-side assist cam surface that is configured to be able to come into contact with the center-side assist cam surface when the pressure plate rotates relative to the clutch center and that generates a force in a direction from the pressure plate toward the clutch center to increase the pressing force between the input side rotating plate and the output side rotating plate, and has reduction means that reduces the restoring force of the clutch spring in the direction from the clutch spring toward the center-side assist cam surface during the period when the center-side assist cam surface and the pressure-side assist cam surface move from being spaced apart in the rotational direction to approaching and contacting each other.

[0009] In another clutch device according to the present invention, the reduction means reduces the restoring force of the clutch spring in the direction from the clutch spring toward the center-side assist cam surface during the period from when the center-side assist cam surface and the pressure-side assist cam surface are spaced apart in the rotational direction until they approach each other and come into contact. In this way, the reduction means reduces the restoring force that may be generated in the clutch spring, thereby preventing the center-side assist cam surface and the pressure-side assist cam surface from suddenly coming into contact with each other due to the restoring force. In other words, the reduction means can prevent the clutch from suddenly engaging. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a clutch device in which sudden engagement of the clutch is suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a clutch device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of the clutch center according to the first embodiment. [Figure 3] FIG. 3 is a plan view of the clutch center according to the first embodiment. [Figure 4] FIG. 4 is a perspective view of the pressure plate according to the first embodiment. [Figure 5] FIG. 5 is a plan view of the pressure plate according to the first embodiment. [Figure 6] FIG. 6 is a perspective view of the pressure plate according to the first embodiment. [Figure 7] FIG. 7 is a plan view of the pressure plate according to the first embodiment. [Figure 8A] FIG. 8A is a schematic diagram illustrating the action of the center-side assist cam surface and the pressure-side assist cam surface. [Figure 8B] FIG. 8B is a schematic diagram illustrating the action of the center-side slipper cam surface and the pressure-side slipper cam surface. [Figure 9]FIG. 9 is a plan view showing a state in which the clutch spring according to the first embodiment is housed in the spring housing portion of the pressure plate. [Figure 10A] FIG. 10A is a cross-sectional view showing the state of the clutch spring when the clutch is disengaged. [Figure 10B] FIG. 10B is a cross-sectional view showing the state of the clutch spring when the clutch is engaged. [Figure 11A] FIG. 11A is a cross-sectional view showing a state of a clutch spring when the clutch is disengaged in the second embodiment. [Figure 11B] FIG. 11B is a cross-sectional view showing the state of the clutch spring when the clutch is engaged in the second embodiment. [Figure 12] FIG. 12 is a plan view showing a state in which the clutch spring according to the second embodiment is housed in the spring housing portion of the pressure plate. [Figure 13] FIG. 13 is a cross-sectional view of a clutch device according to a third embodiment. [Figure 14A] FIG. 14A is a cross-sectional view showing the state of the clutch spring when the clutch is disengaged. [Figure 14B] FIG. 14B is a cross-sectional view showing the state of the clutch spring when the clutch is engaged. [Figure 15A] FIG. 15A is a cross-sectional view showing a state of a clutch spring when the clutch is disengaged in the fourth embodiment. [Figure 15B] FIG. 15B is a cross-sectional view showing the state of the clutch spring when the clutch is engaged in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of a clutch device according to the present invention will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any particular way. Furthermore, the same reference numerals are used to designate members and parts that perform the same functions, and redundant descriptions will be omitted or simplified as appropriate.

[0013] First Embodiment FIG. 1 is a cross-sectional view of a clutch device 10 according to this embodiment. The clutch device 10 is provided on a vehicle such as a motorcycle. The clutch device 10 is a device that transmits or cuts off the rotational driving force of an input shaft (crankshaft) of an engine of the motorcycle to an output shaft 15, for example. The clutch device 10 is a device that transmits or cuts off the rotational driving force of the input shaft to a driving wheel (rear wheel) via the output shaft 15. The clutch device 10 is disposed between the engine and the transmission.

[0014] 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 (an example of a moving direction), the direction in which the pressure plate 70 approaches the clutch center 40 is referred to as a first direction D1, and the direction in which the pressure plate 70 moves away from the clutch center 40 is referred to as a second direction D2. Furthermore, the rotational direction (i.e., the circumferential direction) of the clutch center 40 and the pressure plate 70 is referred to as rotational direction S, the direction from one pressure-side cam portion 90 to the other pressure-side cam portion 90 with respect to rotational direction S is referred to as a first rotational direction S1 (see FIG. 5), and the direction from the other pressure-side cam portion 90 to one pressure-side cam portion 90 is referred to as a second rotational direction S2 (see FIG. 5). In this embodiment, the axial direction of the output shaft 15, the axial direction of the clutch housing 30, the axial direction of the clutch center 40, and the axial direction of the pressure plate 70 are the same as direction D. The pressure plate 70 and the clutch center 40 rotate in a first rotation direction S1. However, the above direction is merely defined for the convenience of explanation and does not limit the installation mode of the clutch device 10 or the present invention in any way.

[0015] 1, the clutch device 10 includes an output shaft 15, an input rotating plate 20, an output rotating plate 22, a clutch housing 30, a clutch center 40, a pressure plate 70, a stopper plate 100, a clutch spring 25, and a reduction means 110. The clutch device 10 is a so-called internal-off type clutch device.

[0016] As shown in Fig. 1, the output shaft 15 is a hollow shaft body. One end of the output shaft 15 rotatably supports an input gear 35 and a clutch housing 30 (described later) via a needle bearing 15A. The output shaft 15 fixedly supports a clutch center 40 via a nut 15B. That is, the output shaft 15 rotates integrally with the clutch center 40. The other end of the output shaft 15 is connected to, for example, a transmission (not shown) of a motorcycle.

[0017] As shown in FIG. 1 , the output shaft 15 includes a hollow portion 15H, which houses a push rod 16A and a push member 16B located adjacent to the push rod 16A. The hollow portion 15H functions as a passageway for clutch oil. The clutch oil flows through the output shaft 15, i.e., the hollow portion 15H. The push rod 16A and the push member 16B are slidably disposed within the hollow portion 15H of the output shaft 15. One end (the end on the left side in the figure) of the push rod 16A is connected to a clutch mechanism (e.g., a clutch operation lever or operation button) of the motorcycle. When the rider operates the clutch, the push rod 16A slides within the hollow portion 15H and presses the push member 16B in the second direction D2. A portion of the push member 16B protrudes outward from the output shaft 15 (in this case, in the second direction D2) and is connected to a release bearing 18 provided on the pressure plate 70. The push rod 16A and the push member 16B are formed to have a smaller inner diameter than the hollow portion 15H, ensuring the flow of clutch oil within the hollow portion 15H.

[0018] The clutch housing 30 is made of an aluminum alloy. The clutch housing 30 is formed in a cylindrical shape with a bottom. As shown in FIG. 1 , the clutch housing 30 has a bottom wall 31 formed in a substantially circular shape and a side wall 33 extending from an edge of the bottom wall 31 in the second direction D2. The clutch housing 30 holds a plurality of input side rotating plates 20.

[0019] As shown in Fig. 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 a rivet 35B via a torque damper 35A. The input gear 35 meshes with a drive gear (not shown) that rotates as the input shaft of the engine rotates. The input gear 35 rotates integrally with the clutch housing 30, independently of the output shaft 15.

[0020] The input side rotating plate 20 is rotationally driven by the rotational drive of the input shaft. As shown in FIG. 1, the input side rotating plate 20 is held on the inner peripheral surface of the side wall 33 of the clutch housing 30. The input side rotating plate 20 is held in the clutch housing 30 by spline fitting. The input side rotating plate 20 is provided so as to be displaceable along the axial direction of the clutch housing 30 (i.e., direction D). The input side rotating plate 20 is provided so as to be rotatable integrally with the clutch housing 30.

[0021] The input side rotating plate 20 is a member 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 formed by aluminum die-casting. Friction material (not shown) made of multiple pieces of paper is attached to the front and back surfaces of the input side rotating plate 20. Grooves several hundred microns deep are formed between the friction materials to hold clutch oil.

[0022] As shown in FIG. 1 , the clutch center 40 is housed in the clutch housing 30. The clutch center 40 is arranged concentrically with the clutch housing 30. The clutch center 40 has a cylindrical main body 42 and a flange 68 extending radially outward from the outer periphery of the main body 42. The clutch center 40 holds an input side rotating plate 20 and a plurality of output side rotating plates 22 arranged alternately in direction D. The clutch center 40 is driven to rotate together with the output shaft 15.

[0023] As shown in Figure 2, the main body 42 includes an annular base wall 43, an outer peripheral wall 45 located radially outside the base wall 43 and extending toward the second direction D2, an output shaft holding portion 50 provided in the center of the base wall 43, and a plurality of center side cam portions 60 connected to the base wall 43 and the outer peripheral wall 45.

[0024] As shown in Fig. 2, the output shaft holding portion 50 is formed in a cylindrical shape. An insertion hole 51 is formed in the output shaft holding portion 50, into which the output shaft 15 (see Fig. 1) is inserted and spline-fitted. The insertion hole 51 is formed to penetrate the base wall 43. An inner circumferential surface 50A of the output shaft holding portion 50, which forms the insertion hole 51, is formed with a plurality of spline grooves along the axial direction. The output shaft 15 is connected to the output shaft holding portion 50 (see Fig. 1).

[0025] As shown in FIG. 2 , the outer peripheral wall 45 of the clutch center 40 is disposed radially outward of the output shaft holding portion 50. A spline fitting portion 46 is provided on the outer peripheral surface of the outer peripheral wall 45. The spline fitting portion 46 has a plurality of center-side fitting teeth 47 extending in the axial direction of the clutch center 40 along the outer peripheral surface of the outer peripheral wall 45, and a plurality of spline grooves 48 formed between adjacent center-side fitting teeth 47 and extending in the axial direction of the clutch center 40. The center-side fitting teeth 47 hold the output-side rotating plate 22. The center-side fitting teeth 47 are aligned in the rotational direction S. The center-side fitting teeth 47 are formed at equal intervals in the rotational direction S. The center-side fitting teeth 47 are formed to have the same shape. The center-side fitting teeth 47 protrude radially outward from the outer peripheral surface of the outer peripheral wall 45. The outer peripheral surface of the center-side fitting teeth 47 is formed substantially parallel to the axis of the output shaft 15 .

[0026] The output side rotating plate 22 is held by the spline fitting portion 46 of the clutch center 40 and the pressure plate 70. A portion of the output side rotating plate 22 is held by the center side fitting teeth 47 and the spline grooves 48 of the clutch center 40 through spline fitting. Another portion of the output side rotating plate 22 is held by the pressure side fitting teeth 77 (see FIG. 4 ) of the pressure plate 70, which will be described later. The output side rotating plate 22 is provided so as to be displaceable along the axial direction of the clutch center 40. The output side rotating plate 22 is provided so as to be rotatable integrally with the clutch center 40.

[0027] The output side rotating plate 22 is a member 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 plate 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 may be provided on both the input side rotating plate 20 and the output side rotating plate 22.

[0028] As shown in FIG. 2, the center-side cam portion 60 is formed in a platform shape having a cam surface made up of an inclined surface that constitutes an Assist & Slipper (registered trademark) mechanism that generates an assist torque, which is a force that increases the pressing force (pressure contact force) between the input-side rotating plate 20 and the output-side rotating plate 22, or a slipper torque, which is a force that quickly separates the input-side rotating plate 20 and the output-side rotating plate 22, resulting in a transition to a half-clutch state. The center-side cam portion 60 is formed to protrude from the base wall 43 in the second direction D2. As shown in FIG. 3, the center-side cam portions 60 are arranged at equal intervals in the rotational 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 FIG. 3 , 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 and a center-side slipper cam surface 60S. The center-side assist cam surface 60A is configured to generate a force in a direction from the pressure plate 70 toward the clutch center 40 (here, a first direction D1) when rotating relative to the pressure plate 70 in order to increase the pressing force (pressure contact force) between the input side rotating plate 20 and the output side rotating plate 22. In this embodiment, when the above force is generated, the position of the pressure plate 70 relative to the clutch center 40 does not change, and the pressure plate 70 does not need to physically approach the clutch center 40. Note that the pressure plate 70 may be physically displaced relative to the clutch center 40. The center-side slipper cam surface 60S is configured to move the pressure plate 70 away from the clutch center 40 when rotating relative to the pressure plate 70 in order to reduce the pressing force (pressure contact force) between the input-side rotating plate 20 and the output-side rotating plate 22. In the center-side cam portions 60 adjacent to each other in the rotational 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 opposite each other in the rotational direction S.

[0030] As shown in FIG. 2, the clutch center 40 has a plurality of boss portions 54 (three in this embodiment). The boss portions 54 are members that support the stopper plate 100 (see FIG. 1). The plurality of boss portions 54 are arranged at equal intervals in the rotational direction S. The boss portions 54 are formed in a cylindrical shape. The boss portions 54 are located radially outward from the output shaft holding portion 50. The boss portions 54 extend toward the pressure plate 70 (i.e., toward the second direction D2). The boss portions 54 are provided on the center-side cam portion 60. The boss portions 54 are located between the center-side assist cam surface 60A and the center-side slipper cam surface 60S in the rotational direction S. A threaded hole 54H is formed in the boss portion 54. The threaded hole 54H extends in the axial direction of the clutch center 40. The bolts 28 (see FIG. 1) used to fix the stopper plate 100 to the clutch center 40 are inserted into the screw holes 54H.

[0031] 2 and 3, the clutch center 40 has a center-side cam hole 43H that penetrates a portion of the base wall 43. The center-side cam hole 43H extends from the side of the output shaft holding portion 50 to the outer peripheral wall 45. The center-side cam hole 43H is formed between a center-side assist cam surface 60A of one center-side cam portion 60 and a center-side slipper cam surface 60S of the other center-side cam portion 60. When viewed from the axial direction of the clutch center 40, the center-side assist cam surface 60A and a portion of the center-side cam hole 43H overlap.

[0032] As shown in FIG. 1 , the pressure plate 70 is provided so as to be able to move toward or away from the clutch center 40 and to rotate relative to it. The pressure plate 70 is configured to be able to press the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 70 is arranged concentrically with the clutch center 40 and the clutch housing 30. The pressure plate 70 has a main body 72 and a flange 98 that is connected to the outer peripheral edge of the main body 72 on the second direction D2 side and extends radially outward. The main body 72 protrudes in the first direction D1 beyond the flange 98. The flange 98 is located at the outer diameter end of the pressure plate 70. The flange 98 is located radially outward beyond a cylindrical portion 80 (see also FIG. 4 ), which will be described later. The pressure plate 70 holds a plurality of output side rotating plates 22 that are arranged alternately with the input side rotating plates 20. The flange 98 is configured to be able to press the input side rotating plate 20 and the output side rotating plate 22.

[0033] 4, the main body 72 includes a cylindrical portion 80, a plurality of pressure-side cam portions 90, and a spring accommodating portion 84 (see FIG. 6). The spring accommodating portion 84 is an example of a accommodating portion.

[0034] The cylindrical portion 80 is formed in a cylindrical shape. The cylindrical portion 80 is formed integrally with the pressure-side cam portion 90. The cylindrical portion 80 accommodates the tip portion 15T (see FIG. 1) of the output shaft 15. The cylindrical portion 80 accommodates the release bearing 18 (see FIG. 1). The cylindrical portion 80 is a portion that receives a pressing force from the push member 16B. The cylindrical portion 80 is a portion that receives clutch oil that flows out from the tip portion 15T of the output shaft 15.

[0035] As shown in Fig. 4, the pressure-side cam portion 90 is formed in a platform shape having a cam surface made up of an inclined surface that constitutes an Assist & Slipper (registered trademark) mechanism that slides on the center-side cam portion 60 to generate assist torque or slipper torque. The pressure-side cam portion 90 is formed so as to protrude in a first direction D1 beyond the flange 98. As shown in Fig. 5, the pressure-side cam portions 90 are arranged at equal intervals in the rotation 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.

[0036] As shown in FIG. 5, the pressure-side cam portion 90 is located radially outward of the cylindrical portion 80. The pressure-side cam portion 90 has a pressure-side assist cam surface 90A (see also FIGS. 6 and 7) and a pressure-side slipper cam surface 90S. The pressure-side assist cam surface 90A is configured to be able to come into contact with the center-side assist cam surface 60A. The pressure-side assist cam surface 90A is configured to generate a force in a direction from the pressure plate 70 toward the clutch center 40 when rotating relative to the clutch center 40, in order to increase the pressing force (pressure contact force) between the input-side rotating plate 20 and the output-side rotating plate 22. The pressure-side slipper cam surface 90S is configured to be able to come into contact with the center-side slipper cam surface 60S. The pressure-side slipper cam surface 90S is configured to move the pressure plate 70 away from the clutch center 40 in order to reduce the pressing force (pressure contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when rotating relative to the clutch center 40. In the pressure-side cam portions 90 adjacent to each other in the rotational direction S, the pressure-side assist cam surface 90A of one pressure-side cam portion 90L and the pressure-side slipper cam surface 90S of the other pressure-side cam portion 90M are arranged opposite each other in the rotational direction S.

[0037] Here, the action of the center-side cam portion 60 and the pressure-side cam portion 90 will be described. When the engine speed increases and the rotational driving force input to the input gear 35 and the clutch housing 30 can be transmitted to the output shaft 15 via the clutch center 40, a rotational force in the first rotational direction S1 is applied to the pressure plate 70, as shown in FIG. 8A. Therefore, a force in the first direction D1 is generated on the pressure plate 70 due to the action of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A. As a result, the pressure plate 70 moves in a direction (first direction D1) closer to the clutch center 40, thereby increasing the pressing force between the input-side rotating plate 20 and the output-side rotating plate 22.

[0038] On the other hand, when the rotation speed of the output shaft 15 exceeds the rotation speed of the input gear 35 and the clutch housing 30 and back torque is generated, a rotational force in the first rotational direction S1 is applied to the clutch center 40, as shown in Fig. 8B. As a result, the action of the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S moves the pressure plate 70 in the second direction D2, releasing the pressure contact force between the input-side rotating plate 20 and the output-side rotating plate 22. This makes it possible to avoid problems with the engine and transmission due to back torque.

[0039] As shown in FIGS. 4 and 5, the pressure plate 70 has a pressure-side cam hole 73H that penetrates a portion of the main body 72. The pressure-side cam hole 73H is located radially outward of the cylindrical portion 80. The pressure-side cam hole 73H extends from a side of the cylindrical portion 80 to a position radially outward of the pressure-side cam portion 90. The pressure-side cam hole 73H is formed between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S of adjacent pressure-side cam portions 90. As shown in FIGS. 5 and 7, when viewed from the axial direction of the pressure plate 70, the pressure-side assist cam surface 90A and a portion of the pressure-side cam hole 73H overlap. When the clutch center 40 and the pressure plate 70 are assembled, the boss portion 54 of the clutch center 40 is located within the pressure-side cam hole 73H.

[0040] As shown in FIG. 4, the pressure plate 70 has a plurality of pressure-side fitting teeth 77 formed on the outer peripheral surface of the main body 72. The pressure-side fitting teeth 77 hold at least one output-side rotating plate 22. The pressure-side fitting teeth 77 are located closer to the first direction S1 than the flange 98. The pressure-side fitting teeth 77 are located radially outward from the cylindrical portion 80. The pressure-side fitting teeth 77 are located radially outward from the pressure-side cam portion 90. The pressure-side fitting teeth 77 are located radially outward from the pressure-side cam portion 90. The plurality of pressure-side fitting teeth 77 are aligned in the rotation direction S. The plurality of pressure-side fitting teeth 77 are arranged at equal intervals in the rotation direction S. Note that in this embodiment, some of the pressure-side fitting teeth 77 have been removed, so the spacing between those portions is wider, but the remaining adjacent pressure-side fitting teeth 77 are arranged at equal intervals.

[0041] As shown in FIGS. 6 and 7, the spring accommodating portion 84 is formed in the pressure-side cam portion 90. The spring accommodating portion 84 is formed so as to be recessed from the second direction D2 toward the first direction D1. The spring accommodating portion 84 is formed in an elliptical shape when viewed from the direction D (see also FIG. 9). The spring accommodating portion 84 accommodates the clutch spring 25 (see FIG. 1). The spring accommodating portion 84 is arranged side by side with the pressure-side assist cam surface 90A in the rotational direction S. Note that "side by side" does not mean that the spring accommodating portion 84 and the pressure-side assist cam surface 90A need not be adjacent to each other; the spring accommodating portion 84 and the pressure-side assist cam surface 90A may be spaced apart from each other in the rotational direction S, or another element (e.g., a recess) integral with the pressure-side cam portion 90 may be provided between the spring accommodating portion 84 and the pressure-side assist cam surface 90A in the rotational direction S. The spring accommodating portion 84 is disposed between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S in the rotational direction S. As shown in FIG. 1 , the spring accommodating portion 84 is formed with a first retaining groove 115 recessed from the second direction D2 toward the first direction D1. The first retaining groove 115 retains an end portion 25A of the clutch spring 25 facing the first direction D1 (described later). The first retaining groove 115 secures the end portion 25A facing the first direction D1 to the pressure plate 70. The first retaining groove 115 is formed in a circular shape when viewed from the direction D. The inner diameter of the first retaining groove 115 is the same as or smaller than the outer diameter of the clutch spring 25. By fitting the end portion 25A of the clutch spring 25 facing the first direction D1 into the first retaining groove 115, the first retaining groove 115 secures the end portion 25A facing the first direction D1 to the pressure plate 70. Note that, as long as the first retaining groove 115 can prevent the end 25A in the first direction D1 from moving in the rotational direction S relative to the pressure plate 70, the first retaining groove 115 does not have to be formed in a circular shape when viewed from the direction D (i.e., there may be a gap between the inner peripheral surface of the first retaining groove 115 and the outer peripheral surface of the clutch spring 25). The first retaining groove 115 may be formed in, for example, an elliptical shape when viewed from the direction D.

[0042] As shown in Figures 1 and 9, the clutch spring 25 is housed in the spring housing 84. The clutch spring 25 urges the pressure plate 70 toward the clutch center 40. That is, the clutch spring 25 urges the pressure plate 70 in the first direction D1. The clutch spring 25 is, for example, a coil spring formed by spirally winding spring steel. The clutch spring 25 is, for example, formed in a cylindrical shape. An end 25A of the clutch spring 25 in the first direction D1 contacts the pressure plate 70. An end 25B of the clutch spring 25 in the second direction D2 contacts the stopper plate 100. 10A and 10B, during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 10A) to when they approach each other and contact each other (see FIG. 10B), the axis 25L of the clutch spring 25 inclines in the direction from the pressure-side assist cam surface 90A toward the clutch spring 25 (i.e., the second rotational direction S2) as it moves from the first direction D1 to the second direction D2 (see FIG. 10B), or is parallel to a line extending in the direction D in which the pressure plate 70 moves (see FIG. 10A). According to this aspect, when the clutch transitions from a disengaged state (see FIG. 10A) to an engaged state (see FIG. 10B), no restoring force is generated in the clutch spring 25 in the direction from the clutch spring 25 toward the pressure-side assist cam surface 90A (i.e., the first rotational direction S1). 10A to 10B, the axis 25L of the clutch spring 25 may be inclined in the direction from the pressure-side assist cam surface 90A toward the clutch spring 25 (i.e., the second rotational direction S2) as it moves from the first direction D1 toward the second direction D2. That is, in the example shown in Fig. 10A, when the clutch is disengaged, the axis 25L of the clutch spring 25 is parallel to a line extending in the direction D, but may be inclined in the direction from the pressure-side assist cam surface 90A toward the clutch spring 25 (i.e., the second rotational direction S2) as it moves from the first direction D1 to the second direction D2.

[0043] As shown in FIG. 1 , the stopper plate 100 is provided so as to be able to come into contact with the pressure plate 70. The stopper plate 100 may also be provided so as to be able to come into contact with a member that is movable in the direction D in conjunction with the pressure plate 70. The stopper plate 100 is a member that prevents the pressure plate 70 from moving away from the clutch center 40 by more than a predetermined distance in the second direction D2. The stopper plate 100 is fixed to the clutch center 40. The stopper plate 100 is fixed to the boss portion 54 of the clutch center 40 by a bolt 28. The stopper plate 100 is fastened and fixed to the boss portion 54 of the clutch center 40 via the bolt 28 with the clutch spring 25 accommodated in the spring accommodating portion 84. The stopper plate 100 is formed in a ring shape in a plan view. The stopper plate 100 is formed with a second retaining groove 120 that is recessed from the first direction D1 toward the second direction D2. The second retaining groove 120 retains the end 25B of the clutch spring 25 in the second direction D2. The second retaining groove 120 fixes the end 25B in the second direction D2 to the stopper plate 100. The second retaining groove 120 is formed in a circular shape when viewed from the direction D. The inner diameter of the second retaining groove 120 is the same as or smaller than the outer diameter of the clutch spring 25. By fitting the end 25B of the clutch spring 25 in the second direction D2 into the second retaining groove 120, the second retaining groove 120 fixes the end 25B in the second direction D2 to the pressure plate 70. Note that, as long as second retaining groove 120 can prevent end 25B in second direction D2 from moving in rotation direction S relative to pressure plate 70, second retaining groove 120 does not have to be formed in a circular shape when viewed from direction D (i.e., there may be a gap between the inner peripheral surface of second retaining groove 120 and the outer peripheral surface of clutch spring 25). Second retaining groove 120 may be formed in an elliptical shape when viewed from direction D, for example.

[0044] 1, the reduction means 110 of this embodiment includes a first retaining groove 115 and a second retaining groove 120. As shown in Figures 10A and 10B, the reduction means 110 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the pressure-side assist cam surface 90A (i.e., in the first rotational direction S1) during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see Figure 10A) to when they approach each other and come into contact (see Figure 10B). In this embodiment, the reduction means 110 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the pressure side assist cam surface 90A (i.e., the first rotational direction S1) by the first retaining groove 115 and the second retaining groove 120 from a state in which the center side assist cam surface 60A and the pressure side assist cam surface 90A are separated in the rotational direction S (see Figure 10A) to a state in which they approach each other and come into contact (see Figure 10B).

[0045] As shown in Figures 10A and 10B, the reduction means 110 suppresses (e.g., restricts) the movement of the end 25A of the clutch spring 25 in the first direction D1 relative to the pressure plate 70 in the rotational direction S, and the movement of the end 25B of the clutch spring 25 in the second direction D2 relative to the stopper plate 100 in the rotational direction S, during the period from when the center side assist cam surface 60A and the pressure side assist cam surface 90A are spaced apart in the rotational direction S (see Figure 10A) to when they approach each other and come into contact (see Figure 10B). In this embodiment, the reduction means 110, by means of the first retaining groove 115 and the second retaining groove 120, suppresses (for example, restricts) the movement of the end 25A of the clutch spring 25 in the first direction D1 relative to the pressure plate 70 in the rotational direction S and the movement of the end 25B of the clutch spring 25 in the second direction D2 relative to the stopper plate 100 in the rotational direction S during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 10A) to when they approach and contact each other (see FIG. 10B). Note that the reduction means 110 slightly permits the end 25A in the first direction D1 to move relative to the pressure plate 70 in the rotational direction S and the end 25B in the second direction D2 to move slightly relative to the stopper plate 100 in the rotational direction S, as long as the reduction means 110 can reduce the restoring force.

[0046] 10A and 10B, the reduction means 110 fixes the end 25A of the clutch spring 25 in the first direction D1 to the pressure plate 70, and fixes the end 25B of the clutch spring 25 in the second direction D2 to the stopper plate 100. In this embodiment, the reduction means 110 fixes the end 25A of the clutch spring 25 in the first direction D1 to the pressure plate 70 by the first retaining groove 115, and fixes the end 25B of the clutch spring 25 in the second direction D2 to the stopper plate 100 by the second retaining groove 120.

[0047] Next, the operation of the clutch device 10 of this embodiment will be described. As described above, the clutch device 10 is disposed between the engine and the transmission of the motorcycle, and transmits or cuts off the rotational driving force of the engine to the transmission when the rider performs a clutch operation (for example, by operating an operating lever or pressing an operating button).

[0048] When the rider of the motorcycle does not operate the clutch, the clutch release mechanism (not shown) does not press the push rod 16A, and the pressure plate 70 presses the input side rotating plate 20 by the biasing force (elastic force) of the clutch spring 25. As a result, the input side rotating plate 20 and the output side rotating plate 22 are pressed against each other and frictionally coupled (i.e., the clutch is engaged), and the clutch center 40 is rotated. As a result, the rotational driving force of the engine is transmitted to the clutch center 40, and the output shaft 15 is rotated.

[0049] On the other hand, when the rider of the motorcycle operates the clutch while the clutch is engaged, the clutch release mechanism (not shown) presses the push rod 16A, displacing the pressure plate 70 in a direction (second direction D2) away from the clutch center 40 against the biasing force of the clutch spring 25. As a result, the clutch center 40 is in a state where the frictional connection between the input side rotating plate 20 and the output side rotating plate 22 is released (i.e., the clutch is disengaged), and the rotational drive of the output shaft 15 is attenuated or stopped. As a result, the rotational drive force of the engine is cut off from the clutch center 40. During the period from the engaged state (see FIG. 10B) to the disengaged state (see FIG. 10A), the reduction means 110 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the pressure-side assist cam surface 90A (i.e., the first rotational direction S1). Here, the clutch spring 25 does not generate the restoring force.

[0050] When the driver releases the clutch (for example, by releasing the operation of the control lever or the operation button) while the clutch is disengaged (see FIG. 10A), the pressure on the pressure plate 70 via the push member 16B by the clutch release mechanism (not shown) is released, and the pressure plate 70 is displaced in a direction (first direction D1) approaching the clutch center 40 by the biasing force of the clutch spring 25. During the period from the clutch disengaged state (see FIG. 10A) to the clutch engaged state (see FIG. 10B), the reduction means 110 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the pressure-side assist cam surface 90A (i.e., the first rotational direction S1). In this state, the clutch spring 25 does not generate the restoring force. Therefore, sudden contact between the center-side assist cam surface 60A and the pressure-side assist cam surface 90A due to the restoring force is suppressed.

[0051] As described above, in the clutch device 10 of this embodiment, the reduction means 110 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the pressure-side assist cam surface 90A (i.e., in the first rotational direction S1) during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S until they approach each other and come into contact. In this way, the reduction means 110 reduces the restoring force that may be generated in the clutch spring 25, thereby preventing the center-side assist cam surface 60A and the pressure-side assist cam surface 90A from suddenly coming into contact with each other due to the restoring force. In other words, the reduction means 110 can prevent the clutch from suddenly engaging.

[0052] In the clutch device 10 of this embodiment, the reduction means 110 suppresses the movement of the end 25A of the clutch spring 25 in the first direction D1 relative to the pressure plate 70 in the rotational direction S, and the movement of the end 25B of the clutch spring 25 in the second direction D2 relative to the stopper plate 100 in the rotational direction S, during the period from when the center side assist cam surface 60A and the pressure side assist cam surface 90A are spaced apart in the rotational direction S to when they approach each other and come into contact, and the axis 25L of the clutch spring 25 inclines in the direction from the pressure side assist cam surface 90A toward the clutch spring 25 (i.e., the second rotational direction S2) as it moves from the first direction D1 to the second direction D2, or is parallel to a straight line extending in the direction D, which is the direction in which the pressure plate 70 moves, during the period from when the center side assist cam surface 60A and the pressure side assist cam surface 90A are spaced apart in the rotational direction S to when they approach each other and come into contact. According to the above embodiment, no restoring force is generated in the clutch spring 25 in the direction from the clutch spring 25 to the pressure-side assist cam surface 90A.

[0053] In the clutch device 10 of this embodiment, the reduction means 110 fixes the end 25A of the clutch spring 25 in the first direction D1 to the pressure plate 70, and fixes the end 25B of the clutch spring 25 in the second direction D2 to the stopper plate 100. According to the above aspect, it is possible to more reliably suppress movement of the clutch spring 25 relative to the pressure plate 70 and the stopper plate 100. As a result, no restoring force is generated in the clutch spring 25 in the direction from the clutch spring 25 to the pressure-side assist cam surface 90A.

[0054] In the clutch device of this embodiment, the reduction means 110 includes a first retaining groove 115 formed in the pressure plate 70, recessed from the second direction D2 toward the first direction D1, and holding the end D1 of the clutch spring 25 in the first direction D1, and a second retaining groove 120 formed in the stopper plate 100, recessed from the first direction D1 toward the second direction D2, and holding the end 25B of the clutch spring 25 in the second direction D2. According to the above aspect, the clutch spring 25 can be more easily fixed to the pressure plate 70 and the stopper plate 100.

[0055] Second Embodiment 11A and 11B are cross-sectional views showing a portion of a clutch device 210 according to the second embodiment. The clutch device 210 includes an output shaft 15, an input rotating plate 20, an output rotating plate 22, a clutch housing 30, a clutch center 40, a pressure plate 270, a stopper plate 300, a clutch spring 225, and a reduction means 310.

[0056] As shown in FIGS. 11A and 12, the pressure plate 270 has a spring accommodating portion 284 that accommodates the clutch spring 225. The spring accommodating portion 284 is an example of an accommodating portion. The spring accommodating portion 284 is formed in the pressure-side cam portion 90. The spring accommodating portion 284 is formed so as to be recessed from the second direction D2 to the first direction D1. The spring accommodating portion 284 is partitioned by a partition wall 284W. The spring accommodating portion 284 is formed in a circular shape when viewed from the direction D (see also FIG. 12). The spring accommodating portion 284 is formed so that its inner diameter increases from the first direction D1 to the second direction D2. The spring accommodating portion 284 is arranged alongside the pressure-side assist cam surface 90A in the rotational direction S. Note that "side by side" does not mean that the spring accommodating portion 284 and the pressure-side assist cam surface 90A need to be adjacent to each other, and the spring accommodating portion 284 and the pressure-side assist cam surface 90A may be spaced apart in the rotational direction S, or another element (for example, a recess or the like) integral with the pressure-side cam portion 90 may be provided between the spring accommodating portion 284 and the pressure-side assist cam surface 90A in the rotational direction S. The spring accommodating portion 284 is disposed between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S in the rotational direction S.

[0057] As shown in FIGS. 11A and 12, the clutch spring 225 is accommodated in the spring accommodating portion 284. The clutch spring 225 contacts the inner circumferential surface 284P of the partition wall 284W over the entirety of the partition wall 284W (i.e., over the entirety of the partition wall 284W in the direction D). The clutch spring 225 is, for example, a conical spring formed by spirally winding spring steel. The clutch spring 225 is, for example, formed in a truncated cone shape whose outer diameter increases from the first direction D1 to the second direction D2. The clutch spring 225 urges the pressure plate 270 toward the clutch center 40. That is, the clutch spring 225 urges the pressure plate 270 in the first direction D1. An end 225A of the clutch spring 225 in the first direction D1 contacts the pressure plate 270. The end 225A in the first direction D1 is provided so as not to slide relative to the pressure plate 270. The end 225B in the second direction D2 of the clutch spring 225 is in contact with the stopper plate 300. The end 225B in the second direction D2 is provided so as to be slidable relative to the stopper plate 300. As shown in FIGS. 11A and 11B, from the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are separated in the rotational direction S (see FIG. 11A) to the state in which they approach each other and contact each other (see FIG. 11B), the axis 225L of the clutch spring 225 is parallel to a line extending in the direction D in which the pressure plate 270 moves. In other words, the clutch spring 225 does not tilt. According to this embodiment, no restoring force is generated in the clutch spring 225 in the direction from the clutch spring 225 toward the pressure-side assist cam surface 90A (i.e., the first rotational direction S1). FIG. 11A shows a state in which the clutch is disengaged, and FIG. 11B shows a state in which the clutch is engaged.

[0058] As shown in FIG. 11A, the stopper plate 300 has the same configuration as the stopper plate 100, except that the second holding groove 120 (see FIG. 10A) is not formed.

[0059] 11A, the reduction means 310 of this embodiment is a partition wall 284W that partitions the spring accommodating portion 284. As shown in FIGS. 11A and 11B, the reduction means 310 reduces the restoring force of the clutch spring 225 in the direction from the clutch spring 225 toward the pressure-side assist cam surface 90A (i.e., the first rotational direction S1) during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 11A) until they approach each other and contact each other (see FIG. 11B). In this embodiment, the reduction means 310 prevents the clutch spring 225 housed in the spring accommodating portion 284 from tilting in the rotational direction S during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 11A) until they approach each other and contact each other (see FIG. 11B). In this embodiment, from the time when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 11A) until they approach each other and come into contact (see FIG. 11B), the clutch spring 225 is in contact with the inner circumferential surface 284P of the partition wall 284W over the entirety of the partition wall 284W (i.e., over the entirety of the partition wall 284W in direction D). Therefore, the clutch spring 225 does not tilt, and no restoring force is generated in the clutch spring 225 in the direction from the clutch spring 225 toward the pressure-side assist cam surface 90A (i.e., in the first rotational direction S1).

[0060] In the clutch device 210 of this embodiment, the reduction means 310 prevents the clutch spring 225 housed in the spring accommodating portion 284 from tilting in the rotational direction S during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S until they approach each other and come into contact. According to the above aspect, the reduction means 310 prevents the clutch spring 225 from tilting in the rotational direction S, so that no restoring force is generated in the clutch spring 225 in a direction from the clutch spring 225 to the pressure-side assist cam surface 90A.

[0061] In the clutch device 210 of this embodiment, the reduction means 310 is a partition wall 284W that partitions the spring accommodating portion 284, and the clutch spring 225 is in contact with the inner circumferential surface 284P of the partition wall 284W over the entirety of the partition wall 284W. According to the above aspect, the clutch spring 225 does not incline in the rotational direction S, and therefore no restoring force is generated in the clutch spring 225 in the direction from the clutch spring 225 to the pressure-side assist cam surface 90A.

[0062] In the clutch device 210 of this embodiment, the spring accommodating portion 284 is formed so that the inner diameter increases from the first direction D1 to the second direction D2, and the clutch spring 225 is formed in a truncated cone shape. According to the above aspect, the clutch spring 225 does not tilt in the rotational direction S, and therefore, no restoring force is generated in the clutch spring 225 in the direction from the clutch spring 225 to the pressure-side assist cam surface 90A.

[0063] Third Embodiment Fig. 13 is a cross-sectional view of a clutch device 410 according to a third embodiment. As shown in Fig. 13, the clutch device 410 includes an output shaft 15, an input rotating plate 20, an output rotating plate 22, a clutch housing 30, a clutch center 440, a pressure plate 470, a lifter plate 500, a clutch spring 25, and a reduction means 510. The clutch device 410 is a so-called externally disconnected type clutch device.

[0064] As shown in FIG. 13, the side wall 33 of the clutch housing 30 extends from the edge of the bottom wall 31 in a first direction D1.

[0065] As shown in FIG. 13, the pressure plate 470 has a plurality of boss portions 554 (three in this embodiment). The boss portions 554 are members that support the lifter plate 500. The plurality of boss portions 554 are arranged at equal intervals in the rotational direction S. The boss portions 554 are formed in a cylindrical shape. The boss portions 554 extend toward the clutch center 440 (i.e., toward the first direction D1). The boss portions 554 are provided on the pressure-side cam portion 90. As shown in FIGS. 14A and 14B, the boss portions 554 are located between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface 90S with respect to the rotational direction S. A screw hole 554H is formed in the boss portion 554. The screw hole 554H extends in the axial direction of the pressure plate 470. Bolts 28 (see FIG. 13) used to fix the lifter plate 500 to the pressure plate 470 are inserted into the screw holes 554H.

[0066] As shown in FIG. 13, the clutch center 440 has a spring accommodating portion 484. The spring accommodating portion 484 is an example of an accommodating portion. The spring accommodating portion 484 is formed in the main body 42. The spring accommodating portion 484 is formed in the center-side cam portion 60. The spring accommodating portion 484 is formed so as to be recessed from the first direction D1 toward the second direction D2. The spring accommodating portion 484 is formed in an elliptical shape when viewed from the direction D. The spring accommodating portion 484 accommodates the clutch spring 25. As shown in FIGS. 14A and 14B, the spring accommodating portion 484 is arranged alongside the center-side assist cam surface 60A in the rotational direction S. Note that "side by side" does not necessarily mean that the spring accommodating portion 484 and the center-side assist cam surface 60A are adjacent to each other. The spring accommodating portion 484 and the center-side assist cam surface 60A may be spaced apart in the rotational direction S, or another element (e.g., a recess) integral with the center-side cam portion 60 may be provided between the spring accommodating portion 484 and the center-side assist cam surface 60A in the rotational direction S. The spring accommodating portion 484 is disposed between the center-side assist cam surface 60A and the center-side slipper cam surface 60S in the rotational direction S. A first retaining groove 515 recessed from the first direction D1 toward the second direction D2 is formed in the spring accommodating portion 484. The first retaining groove 515 retains the end portion 25B of the clutch spring 25 in the second direction D2. The first retaining groove 515 fixes the end portion 25B in the second direction D2 to the clutch center 440. The first holding groove 515 has the same configuration as the first holding groove 115 .

[0067] As shown in FIG. 13, the clutch spring 25 is accommodated in a spring accommodating portion 484. An end portion 25B of the clutch spring 25 in the second direction D2 contacts the clutch center 440. An end portion 25A of the clutch spring 25 in the first direction D1 contacts the lifter plate 500. As shown in FIGS. 14A and 14B, during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 14A) to when they approach each other and contact each other (see FIG. 14B), the axis 25L of the clutch spring 25 inclines in the direction from the center-side assist cam surface 60A toward the clutch spring 25 (i.e., the first rotational direction S1) as it moves from the second direction D2 toward the first direction D1 (see FIG. 14B), or is parallel to a straight line extending in the direction D, which is the direction in which the pressure plate 470 moves (see FIG. 14A). According to this embodiment, when the clutch transitions from a disengaged state (see FIG. 14A) to an engaged state (see FIG. 14B), no restoring force is generated in the clutch spring 25 in a direction from the clutch spring 25 toward the center-side assist cam surface 60A (i.e., second rotational direction S2). The axis 25L of the clutch spring 25 may be inclined in a direction from the center-side assist cam surface 60A toward the clutch spring 25 (i.e., first rotational direction S1) as it moves from the second direction D2 toward the first direction D1 throughout the entire range from the state of FIG. 14A to the state of FIG. 14B.

[0068] As shown in FIG. 13 , the lifter plate 500 is provided so as to be able to come into contact with the clutch center 40. The lifter plate 500 may be provided so as to be able to come into contact with a member that rotates in conjunction with the clutch center 400. The lifter plate 500 is a member for displacing the pressure plate 470 in direction D. The lifter plate 500 is a member that prevents the pressure plate 470 from being separated from the clutch center 40 by more than a predetermined distance in the second direction D2. The lifter plate 500 is fixed to the pressure plate 470. The lifter plate 500 is fixed to a boss portion 554 of the pressure plate 470 by a bolt 28. The lifter plate 500 rotates integrally with the pressure plate 470. The lifter plate 500 moves in direction D with respect to the clutch center 440 and rotates relatively to the clutch center 440. The lifter plate 500 is formed in a disk shape. Lifter plate 500 is provided with release bearing 503. Release bearing 503 is a member pressed by release fork 512 of a clutch release mechanism (not shown). Here, the clutch release mechanism is a mechanical device that presses release bearing 503 toward output shaft 15 (i.e., toward second direction D2) via release fork 512 when a driver operates a clutch operating lever (not shown) in a vehicle such as a motorcycle equipped with clutch device 410. Lifter plate 500 supports clutch spring 25 housed in spring housing portion 484 of clutch center 440. Lifter plate 500 is formed with insertion holes 504H into which bolts 28 are inserted to secure lifter plate 500 to pressure plate 470. Lifter plate 500 is formed with second retaining grooves 520 recessed from second direction D2 toward first direction D1. The second retaining groove 520 retains the end portion 25A of the clutch spring 25 in the first direction D1. The second retaining groove 520 fixes the end portion 25A in the first direction D1 to the lifter plate 500. The second retaining groove 520 has a similar configuration to the second retaining groove 120.

[0069] 13, the reduction means 510 of this embodiment includes a first retaining groove 515 and a second retaining groove 520. As shown in Figures 14A and 14B, the reduction means 510 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the center-side assist cam surface 60A (i.e., in the second rotational direction S2) during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see Figure 14A) to when they approach each other and come into contact (see Figure 14B). In this embodiment, the reduction means 510 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the center side assist cam surface 60A (i.e., the second rotational direction S2) by the first retaining groove 515 and the second retaining groove 520 from a state in which the center side assist cam surface 60A and the pressure side assist cam surface 90A are separated in the rotational direction S (see Figure 14A) to a state in which they approach each other and come into contact (see Figure 14B).

[0070] As shown in Figures 14A and 14B, the reduction means 510 prevents the end 25B of the clutch spring 25 in the second direction D2 from moving relative to the clutch center 440 in the rotational direction S, and prevents the end 25A of the clutch spring 25 in the first direction D1 from moving relative to the lifter plate 500 in the rotational direction S, from the state in which the center side assist cam surface 60A and the pressure side assist cam surface 90A are spaced apart in the rotational direction S (see Figure 14A) until they approach each other and come into contact (see Figure 14B). In this embodiment, the reduction means 510, by means of the first retaining groove 515 and the second retaining groove 520, suppresses the end 25B of the clutch spring 25 in the second direction D2 from moving relative to the clutch center 440 in the rotational direction S and the end 25A of the clutch spring 25 in the first direction D1 from moving relative to the lifter plate 500 in the rotational direction S during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 14A) to when they approach and contact each other (see FIG. 14B). Note that the reduction means 510 slightly permits the end 25B of the clutch spring 25 in the second direction D2 to move relative to the clutch center 440 in the rotational direction S and the end 25A of the clutch spring 25 in the first direction D1 to move relative to the lifter plate 500 in the rotational direction S, as long as the reduction means 510 can reduce the restoring force.

[0071] 14A and 14B, reduction means 510 fixes end 25B of clutch spring 25 in second direction D2 to clutch center 440, and fixes end 25A of clutch spring 25 in first direction D1 to lifter plate 500. In this embodiment, reduction means 510 fixes end 25B of clutch spring 25 in second direction D2 to clutch center 440 by first retaining groove 515, and fixes end 25A of clutch spring 25 in first direction D1 to lifter plate 500 by second retaining groove 520.

[0072] As described above, in the clutch device 410 of this embodiment, the reduction means 510 reduces the restoring force of the clutch spring 25 in the direction from the clutch spring 25 toward the center-side assist cam surface 60A (i.e., in the second rotational direction S2) during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S until they approach each other and come into contact. In this way, the reduction means 510 reduces the restoring force that may be generated in the clutch spring 25, thereby preventing the center-side assist cam surface 60A and the pressure-side assist cam surface 90A from suddenly coming into contact with each other due to the restoring force. In other words, the reduction means 510 can prevent the clutch from suddenly engaging.

[0073] In the clutch device 410 of this embodiment, the reduction means 510 suppresses the movement of the end 25B of the clutch spring 25 in the second direction D2 relative to the clutch center 440 in the rotational direction S, and the movement of the end 25A of the clutch spring 25 in the first direction D1 relative to the lifter plate 500, during the period from when the center side assist cam surface 60A and the pressure side assist cam surface 90A move from being spaced apart in the rotational direction S to when they approach each other and contact each other, and the axis 25L of the clutch spring 25 inclines in the direction from the center side assist cam surface 60A toward the clutch spring 25 (i.e., the first rotational direction S1) as it moves from the second direction D2 to the first direction D1, or is parallel to a straight line extending in the direction D, which is the direction in which the pressure plate 70 moves, during the period from when the center side assist cam surface 60A and the pressure side assist cam surface 90A move from being spaced apart in the rotational direction S to when they approach each other and contact each other. According to the above embodiment, no restoring force is generated in the clutch spring 25 in the direction from the clutch spring 25 to the center side assist cam surface 60A.

[0074] <Fourth embodiment> 15A and 15B are cross-sectional views showing a portion of a clutch device 610 according to the fourth embodiment. The clutch device 610 includes an output shaft 15, an input rotating plate 20, an output rotating plate 22, a clutch housing 30, a clutch center 540, a pressure plate 470, a lifter plate 600, a clutch spring 225, and a reduction means 710.

[0075] As shown in Figures 15A and 15B, the clutch center 540 has a spring accommodating portion 584 that accommodates the clutch spring 225. The spring accommodating portion 584 is an example of an accommodating portion. The spring accommodating portion 584 is formed in the center-side cam portion 60. The spring accommodating portion 584 is formed so as to be recessed from the first direction D1 to the second direction D2. The spring accommodating portion 584 is partitioned by a partition wall 584W. The spring accommodating portion 584 is formed in a circular shape when viewed from the direction D. The spring accommodating portion 584 is formed so that its inner diameter increases as it goes from the second direction D2 to the first direction D1. The spring accommodating portion 584 is arranged alongside the center-side assist cam surface 60A in the rotational direction S. Note that "side by side" does not mean that the spring accommodating portion 584 and the center-side assist cam surface 60A need to be adjacent to each other; the spring accommodating portion 584 and the center-side assist cam surface 60A may be spaced apart in the rotational direction S, or another element (such as a recess) integral with the center-side cam portion 60 may be provided between the spring accommodating portion 584 and the center-side assist cam surface 60A in the rotational direction S. The spring accommodating portion 584 is disposed between the center-side assist cam surface 60A and the center-side slipper cam surface 60S in the rotational direction S.

[0076] As shown in FIGS. 15A and 15B, the clutch spring 225 is accommodated in the spring accommodating portion 584. The clutch spring 225 contacts the inner circumferential surface 584P of the partition wall 584W over the entirety of the partition wall 584W (i.e., over the entirety of the partition wall 584W in the direction D). The clutch spring 225 urges the pressure plate 470 toward the clutch center 540. That is, the clutch spring 225 urges the pressure plate 470 in the first direction D1. An end 225B of the clutch spring 225 in the second direction D2 contacts the clutch center 540. The end 225B in the second direction D2 is provided so as to be unable to slide relative to the clutch center 540. An end 225A of the clutch spring 225 in the first direction D1 contacts the lifter plate 600. The end 225A in the first direction D1 is provided slidably relative to the lifter plate 600. From the state in which the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 15A) until they approach each other and contact each other (see FIG. 15B), the axis 225L of the clutch spring 225 is parallel to a line extending in the direction D, which is the direction in which the pressure plate 270 moves. In other words, the clutch spring 225 does not tilt. According to this embodiment, the clutch spring 225 does not generate a restoring force in the direction from the clutch spring 225 toward the center-side assist cam surface 60A (i.e., the second rotational direction S2). Note that FIG. 15A shows a state in which the clutch is disengaged, and FIG. 15B shows a state in which the clutch is engaged.

[0077] As shown in FIG. 15A, lifter plate 600 has the same configuration as lifter plate 500 except that second holding groove 520 (see FIG. 14A) is not formed.

[0078] As shown in Fig. 15A, the reduction means 710 of this embodiment is a partition wall 584W that partitions the spring accommodating portion 584. As shown in Figs. 15A and 15B, the reduction means 710 reduces the restoring force of the clutch spring 225 in the direction from the clutch spring 225 toward the center-side assist cam surface 60A (i.e., the second rotational direction S2) during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see Fig. 15A) until they approach each other and contact each other (see Fig. 15B). In this embodiment, the reduction means 710 prevents the clutch spring 225 housed in the spring accommodating portion 584 from tilting in the rotational direction S during the period from when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see Fig. 15A) until they approach each other and contact each other (see Fig. 15B). In this embodiment, from the time when the center-side assist cam surface 60A and the pressure-side assist cam surface 90A are spaced apart in the rotational direction S (see FIG. 15A) until they approach and contact each other (see FIG. 15B), the clutch spring 225 is in contact with the inner circumferential surface 584P of the partition wall 584W over the entirety of the partition wall 584W (i.e., over the entirety of the partition wall 584W in direction D). Therefore, the clutch spring 225 does not tilt, and no restoring force is generated in the clutch spring 225 in the direction from the clutch spring 225 toward the center-side assist cam surface 60A (i.e., in the second rotational direction S2).

[0079] In the clutch device 610 of this embodiment, the reduction means 710 prevents the clutch spring 225 housed in the spring accommodating portion 584 from tilting in the rotational direction S during the period from when the center side assist cam surface 60A and the pressure side assist cam surface 90A are spaced apart in the rotational direction S until they approach each other and come into contact. According to the above aspect, the reduction means 710 prevents the clutch spring 225 from tilting in the rotational direction S, so that no restoring force is generated in the clutch spring 225 in the direction from the clutch spring 225 to the center side assist cam surface 60A.

[0080] In the clutch device 610 of this embodiment, the reduction means 710 is a partition wall 584W that partitions the spring accommodating portion 584, and the clutch spring 225 is in contact with an inner circumferential surface 584P of the partition wall 584W over the entirety of the partition wall 584W. According to the above aspect, the clutch spring 225 does not incline in the rotational direction S, and therefore no restoring force is generated in the clutch spring 225 in a direction from the clutch spring 225 toward the center-side assist cam surface 60A.

[0081] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

[0082] In the first embodiment described above, the end 25A of the clutch spring 25 in the first direction D1 is fixed to the pressure plate 70 by the first retaining groove 115. However, the fixing method is not limited to this. For example, the end 25A in the first direction D1 may be fixed by adhering it to the pressure plate 70, or a high-friction member may be disposed at the contact portion between the pressure plate 70 and the end 25A in the first direction D1 to fix them to each other, or the end 25A in the first direction D1 may be fixed to the pressure plate 70 by a protrusion or the like. The end 25B of the clutch spring 25 in the second direction D2 may also be fixed in a similar manner. Furthermore, in the third embodiment, the fixing method for fixing the end 25B of the clutch spring 25 in the second direction D2 to the clutch center 440 and the fixing method for fixing the end 25A of the clutch spring 25 in the first direction D1 to the lifter plate 500 may also be the same.

[0083] In the second embodiment described above, clutch spring 225 is prevented from tilting by contacting inner circumferential surface 284P of partition wall 284W over the entirety of partition wall 284W, but this is not limiting. For example, tilting of clutch spring 225 may be prevented by a protrusion or the like that protrudes from inner circumferential surface 284P of partition wall 284W toward clutch spring 225. Also, in the fourth embodiment, tilting of clutch spring 225 may be prevented by a protrusion or the like that protrudes from inner circumferential surface 584P of partition wall 584W toward clutch spring 225.

[0084] In the second embodiment described above, clutch spring 225 is in contact with inner circumferential surface 284P of partition wall 284W over the entirety of partition wall 284W to prevent clutch spring 225 from tilting, but as long as the restoring force can be reduced, a small gap may be provided between the outer circumferential surface of clutch spring 225 and the inner circumferential surface of partition wall 284W over the entirety or part of partition wall 284W. The same applies to the fourth embodiment.

[0085] In the first to fourth embodiments described above, the clutch centers 40, 440, 540 hold the output side rotating plates 22, but the clutch centers 40, 440, 540 do not have to hold the output side rotating plates 22. That is, all the output side rotating plates 22 may be held by the pressure plates 70, 270, 470, and the clutch centers 40, 440, 540 may not hold any of the output side rotating plates 22. [Explanation of symbols]

[0086] 10. Clutch device 15 Output shaft 20 Input side rotating plate 22 Output side rotating plate 25 clutch spring 25A End in the first direction 25B End in second direction 25L axis 40 Clutch center 54 Boss section 60 Center side cam part 60A Center side assist cam surface 60S Center side slipper cam surface 70 Pressure Plate 84 Spring housing (housing) 90 Pressure side cam 90A Pressure side assist cam surface 90S Pressure side slipper cam surface 100 Stopper plate 110 Mitigation Measures 115 1st retaining groove 120 2nd retaining groove

Claims

1. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft, and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be able to approach or move away from the clutch center and to be rotatable relative to the clutch center, that holds one or more of the plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that can press the input side rotating plate and the output side rotating plate; a clutch spring that urges the pressure plate in the first direction, when a direction in which the pressure plate approaches the clutch center is defined as a first direction and a direction in which the pressure plate moves away from the clutch center is defined as a second direction; and a stopper plate fixed to the clutch center and preventing the pressure plate from moving away from the clutch center in the second direction by more than a predetermined distance, an end of the clutch spring in the first direction contacts the pressure plate, and an end of the clutch spring in the second direction contacts the stopper plate; The clutch center is a center-side assist cam surface that generates a force from the pressure plate toward the clutch center in order to increase the pressing force between the input-side rotary plate and the output-side rotary plate when the pressure plate rotates relative to the pressure plate; and a center-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input-side rotary plate and the output-side rotary plate, The pressure plate is a pressure-side assist cam surface that is configured to be able to come into contact with the center-side assist cam surface when the pressure plate rotates relative to the clutch center, and that generates a force from the pressure plate in a direction toward the clutch center in order to increase the pressing force between the input-side rotating plate and the output-side rotating plate; 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. a housing portion that is arranged alongside the pressure-side assist cam surface in the rotational direction of the pressure plate and that houses the clutch spring, A clutch device in which, in a cross-sectional view along the circumferential direction of the clutch center and the pressure plate, the axis of the clutch spring is parallel to a straight line extending in the direction of movement of the pressure plate from a state in which the center side assist cam surface and the pressure side assist cam surface are in contact with each other to a state in which the center side slipper cam surface and the pressure side slipper cam surface are in contact with each other.

2. the pressure plate includes a partition wall that partitions the storage section, 2. The clutch device according to claim 1, wherein the clutch spring is in contact with the inner circumferential surface of the partition wall over the entire area of the partition wall.

3. The housing portion is formed so that an inner diameter thereof increases as it goes from the first direction to the second direction, 2. The clutch device according to claim 1, wherein the clutch spring is formed in a truncated cone shape.

4. A clutch device that transmits or cuts off the rotational driving force of an input shaft to an output shaft, a clutch center accommodated in a clutch housing that holds a plurality of input side rotary plates that are rotationally driven by the rotational drive of the input shaft, and that is rotationally driven together with the output shaft; a pressure plate that is provided so as to be able to approach or move away from the clutch center and to be rotatable relative to the clutch center, that holds one or more of the plurality of output side rotating plates that are arranged alternately with the input side rotating plate, and that can press the input side rotating plate and the output side rotating plate; a clutch spring that urges the pressure plate in the first direction, when a direction in which the pressure plate approaches the clutch center is defined as a first direction and a direction in which the pressure plate moves away from the clutch center is defined as a second direction; and a lifter plate fixed to the pressure plate and preventing the pressure plate from being spaced apart from the clutch center in the second direction by more than a predetermined distance, an end of the clutch spring in the first direction contacts the lifter plate, and an end of the clutch spring in the second direction contacts the clutch center; The clutch center is a center-side assist cam surface that generates a force from the pressure plate toward the clutch center in order to increase the pressing force between the input-side rotary plate and the output-side rotary plate when the pressure plate rotates relative to the pressure plate; and a center-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input-side rotary plate and the output-side rotary plate. a housing portion that is arranged alongside the center-side assist cam surface in the rotational direction of the clutch center and that houses the clutch spring, The pressure plate is a pressure-side assist cam surface that is configured to be able to come into contact with the center-side assist cam surface when the pressure plate rotates relative to the clutch center, and that generates a force from the pressure plate in a direction toward the clutch center in order to increase the pressing force between the input-side rotating plate and the output-side rotating plate; and a pressure-side slipper cam surface that moves the pressure plate away from the clutch center in order to decrease the pressing force between the input-side rotating plate and the output-side rotating plate, A clutch device in which, in a cross-sectional view along the circumferential direction of the clutch center and the pressure plate, the axis of the clutch spring is parallel to a straight line extending in the direction of movement of the pressure plate from a state in which the center side assist cam surface and the pressure side assist cam surface are in contact with each other to a state in which the center side slipper cam surface and the pressure side slipper cam surface are in contact with each other.

5. The clutch center includes a partition wall that partitions the housing portion, 5. The clutch device according to claim 4, wherein the clutch spring is in contact with the inner circumferential surface of the partition wall over the entire area of the partition wall.

6. The housing portion is formed so that an inner diameter thereof increases as it goes from the second direction to the first direction, 5. The clutch device according to claim 4, wherein the clutch spring is formed in a truncated cone shape.

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