Clutch device

Abstract

A clutch device 10 is provided with a centrifugal clutch mechanism 120 having a weight member 130. The centrifugal clutch mechanism 120 is provided with a holding member 140 for holding the weight member 130, a spring 160 for urging the weight member 130, and a pressure contact member 150 for bringing an input-side rotary plate 20 and an output-side rotary plate 22 into pressure contact with each other. The holding member 140 is provided with an engaging hook 143 that projects from an outer peripheral edge 141E of a body 141 toward an outer side M1 in a radial direction M and engages with a clutch housing 30, and an accommodating recess 145 for accommodating the weight member 130. The body 141 is provided with a thick part 141T including a wall part 141A positioned between the engaging hook 143 and the accommodating recess 145 with respect to the radial direction M, and a projecting part 141B that projects from the wall part 141A toward an inner side M2 in the radial direction M and partitions a part of the accommodating recess 145.

Description

Clutch device

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

[0002] Straddle-type vehicles such as motorcycles are equipped with a clutch device that can transmit and interrupt the rotational driving force of a driving source such as an engine to a driving wheel. For example, Patent Document 1 discloses a clutch device that has an input member (hereinafter referred to as an input shaft) connected to the engine, an output member (hereinafter referred to as an output shaft) connected to the driving wheel, a clutch member (hereinafter referred to as a clutch center) connected to the output shaft, and a pressure member that can move toward or away from the clutch center.

[0003] The clutch device in Patent Document 1 also includes a centrifugal clutch mechanism that includes a weight member that moves radially and a retaining member that houses the weight member. The retaining member has an engagement pawl that engages with the clutch housing and is configured to rotate together with the clutch housing. The engagement pawl is located radially outward of the weight member. The weight member moves from a radially inner position to a radially outer position due to centrifugal force generated by rotation of the clutch housing, and is configured to press a driving side clutch plate (hereinafter referred to as an input side rotating plate) and a driven side clutch plate (hereinafter referred to as an output side rotating plate) together, thereby transmitting engine driving force to the wheels.

[0004] JP 2022-30211 A

[0005] However, since the rotational driving force of the clutch housing is transmitted to the retaining member via the engagement pawl, a relatively large load is applied to the engagement pawl. If the engagement pawl is damaged, a problem may arise in that the rotational driving force of the clutch housing cannot be sufficiently transmitted to the weight member. For this reason, there is a need for a clutch device in which damage to the engagement pawl is suppressed.

[0006] 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 damage to the engagement pawls is suppressed.

[0007] The inventors of the present invention decided to increase the torsional strength of the engaging claws by increasing their thickness. Furthermore, they discovered that a relatively large load is applied to the engaging claws when the weight members located on the radially inner side of the engaging claws move from their radially inner position to their radially outer position due to centrifugal force. Therefore, they decided to improve the strength of the entire engaging claws by changing the shape of the periphery of the engaging claws.

[0008] 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 member that is provided so as to be able to approach or move away from the clutch center and that holds at least some of the 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; and a plurality of weight members that are configured to be movable from a radially inner position to an outer position by centrifugal force that accompanies rotation of the clutch housing, and that when the weight members are at the radially outer positions, press the input side rotating plates against the output side rotating plates to enable the rotational drive force of the input shaft to be transmitted to the output shaft, and when the weight members are at the radially inner positions, release the pressing force between the input side rotating plates and the output side rotating plates to allow the rotational drive force of the input shaft to be transmitted to the output shaft and a centrifugal clutch mechanism capable of blocking transmission of the weight member to the input side rotating plate, the centrifugal clutch mechanism comprising: a holding member that holds the weight member movably between the radially inner position and the radially outer position; a biasing member that is provided to the holding member and biases the weight member inward in the radial direction; and a pressing member that moves in the axial direction of the output shaft as the weight member moves from the radially inner position to the radially outer position, thereby pressing the input side rotating plate and the output side rotating plate together, The retaining member comprises a ring-shaped main body, an engaging claw that protrudes radially outward from the outer peripheral edge of the main body and engages with the clutch housing, and an accommodating recess that is formed in the main body so as to be recessed in the axial direction of the output shaft and that accommodates the weight member so that it can move radially in the radial direction, and the main body has a thick portion that includes a wall portion located between the engaging claw and the accommodating recess in the radial direction, and a protruding portion that protrudes radially inward from the wall portion and defines a portion of the accommodating recess.

[0009] In the clutch device according to the present invention, the main body of the retaining member includes a thick portion including a wall portion located radially between the engaging pawl and the accommodating recess, and a protrusion portion protruding radially inward from the wall portion and defining a portion of the accommodating recess. According to the above aspect, the thick portion is provided between the engaging pawl and the accommodating recess, increasing the radial thickness by the amount of the thick portion, thereby increasing the rigidity of the engaging pawl. As a result, even if a weight member comes into contact with the protrusion portion, the increased rigidity of the engaging pawl can prevent damage to the engaging pawl.

[0010] 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 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 is rotationally driven together with the output shaft; a pressure member that is provided so as to be able to approach or move away from the clutch center and that holds at least some of the 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; and a plurality of weight members that are configured to be movable from a radially inner position to an outer position by centrifugal force that accompanies rotation of the clutch housing, and when the weight members are at the radially outer position, they press the input side rotating plates against the output side rotating plates, enabling the rotational drive force of the input shaft to be transmitted to the output shaft, and when the weight members are at the radially inner position, they release the pressing force between the input side rotating plates and the output side rotating plates, thereby transmitting the rotational drive force of the input shaft to the output shaft. and a centrifugal clutch mechanism capable of blocking the input side rotating plate and the output side rotating plate from being pressed against each other, the centrifugal clutch mechanism comprising: a holding member that holds the weight member movably between the radially inner position and the radially outer position; a biasing member that is provided on the holding member and biases the weight member inward in the radial direction; and a pressing member that moves in the axial direction of the output shaft as the weight member moves from the radially inner position to the radially outer position, thereby pressing the input side rotating plate and the output side rotating plate into pressing contact, and the holding member The clutch housing comprises a ring-shaped main body, an engaging claw that protrudes radially outward from the outer peripheral edge of the main body and engages with the clutch housing, and an accommodating recess that is formed in the main body so as to be recessed in the axial direction of the output shaft and that accommodates the weight member so that it can move radially in the radial direction, the main body having a wall portion located between the engaging claw and the accommodating recess in the radial direction, and the radial length of the wall portion is longer than the radial length from the outer peripheral edge of the main body to the radially outer end of the engaging claw.

[0011] In another clutch device according to the present invention, the body of the retaining member includes a wall portion located radially between the engaging pawl and the accommodating recess, and the radial length of the wall portion is longer than the radial length from the outer peripheral edge of the body to the radially outer end of the engaging pawl. According to the above aspect, the wall portion is relatively thick, which increases the rigidity of the engaging pawl. As a result, even if a weight member comes into contact with the wall portion, the increased rigidity of the engaging pawl can prevent damage to the engaging pawl.

[0012] According to the present invention, it is possible to provide a clutch device in which damage to the engagement pawls is suppressed.

[0013] FIG. 1 is a cross-sectional view of a clutch device according to the first embodiment. FIG. 2 is a perspective view of a first clutch center according to the first embodiment. FIG. 3 is a perspective view of the first clutch center according to the first embodiment. FIG. 4 is a perspective view of a second clutch center according to the first embodiment. FIG. 5 is a plan view of the second clutch center according to the first embodiment. FIG. 6 is a perspective view of a pressure member according to the first embodiment. FIG. 7 is a perspective view of a pressure member according to the first embodiment. FIG. 8A is a schematic view illustrating the functions of a center-side assist cam surface and a pressure-side assist cam surface. FIG. 8B is a schematic view illustrating the functions of a center-side slipper cam surface and a pressure-side slipper cam surface. FIG. 9A is a perspective view of a portion of a centrifugal clutch mechanism according to the first embodiment, and is a plan view illustrating a state in which a weight member is positioned radially inward. FIG. 9B is a plan view of a portion of a centrifugal clutch mechanism according to the first embodiment, and is a plan view illustrating a state in which a weight member is positioned radially inward. FIG. 10 is a plan view of a retaining member according to the first embodiment. FIG. 11 is a perspective view of a retaining member according to the first embodiment. FIG. 12A is an enlarged plan view showing a portion of the holding member according to the first embodiment. FIG. 12B is an enlarged plan view showing a portion of the holding member according to the first embodiment. FIG. 13 is a perspective view showing a weight member according to the first embodiment. FIG. 14 is a plan view showing a weight member according to the first embodiment. FIG. 15 is a perspective view showing a weight member according to the first embodiment. FIG. 16 is a bottom view showing a weight member according to the first embodiment. FIG. 17 is a side view showing a weight member according to the first embodiment. FIG. 18 is a plan view showing a portion of the centrifugal clutch mechanism according to the first embodiment, showing a state in which the weight member is positioned radially outward. FIG. 19 is an enlarged plan view showing a state in which the weight member is positioned radially outward. FIG. 20 is a cross-sectional view showing a portion of the clutch device according to the first embodiment, showing a state in which the weight member is positioned radially inward. FIG. 21 is a cross-sectional view showing a portion of the clutch device according to the first embodiment, showing a state in which the weight member is positioned radially outward. FIG. 22 is a cross-sectional view of a clutch device according to a second embodiment. FIG. 23 is a perspective view showing a holding member according to the second embodiment.FIG. 24 is a perspective view showing a weight member according to the second embodiment. FIG. 25 is a bottom view showing a weight member according to the second embodiment. FIG. 26 is a side view showing a weight member according to the second embodiment. FIG. 27 is a cross-sectional view showing a portion of a clutch device according to the second embodiment, illustrating a state in which the weight member is positioned radially inward. FIG. 28 is a cross-sectional view showing a portion of a clutch device according to the second embodiment, illustrating a state in which the weight member is positioned radially outward. FIG. 29 is a plan view showing a portion of a centrifugal clutch mechanism according to the second embodiment, illustrating a state in which the weight member is positioned radially inward. FIG. 30 is a plan view showing a portion of a centrifugal clutch mechanism according to the second embodiment, illustrating a state in which the weight member is positioned radially outward. FIG. 31 is an enlarged plan view showing a state in which the weight member of a clutch device according to the third embodiment is positioned radially inward. FIG. 32 is a plan view showing a portion of a centrifugal clutch mechanism according to a fourth embodiment, illustrating a state in which the weight member is positioned radially inward. FIG. 33A is a graph showing the relationship between the engine speed and the positions of the first weight member and the second weight member. FIG. 33B is a graph showing the relationship between the engine speed and the position of the pressing member. FIG. 34 is a plan view showing a portion of a centrifugal clutch mechanism according to a fifth embodiment, showing a state in which the weight member is positioned radially inward. FIG. 35 is a plan view showing a portion of a centrifugal clutch mechanism according to a sixth embodiment, showing a state in which the weight member is positioned radially inward. FIG. 36 is a plan view showing a portion of a centrifugal clutch mechanism according to a seventh embodiment, showing a state in which the weight member is positioned radially inward. FIG. 37 is a cross-sectional view showing a centrifugal clutch mechanism according to an eighth embodiment and its periphery. FIG. 38 is a plan view showing a portion of a centrifugal clutch mechanism according to an eighth embodiment, showing a state in which the weight member is positioned radially inward. FIG. 39 is a perspective view showing a weight member and a spring according to the eighth embodiment. FIG. 40 is a perspective view showing a pressing member according to the eighth embodiment. Figure 41 is a schematic diagram showing a part of a centrifugal clutch mechanism according to a first modified example. Figure 42 is a schematic diagram showing a part of a centrifugal clutch mechanism according to a second modified example.

[0014] 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 way. Furthermore, the same reference numerals are used to designate components and parts that perform the same functions, and redundant descriptions will be omitted or simplified as appropriate.

[0015] <First embodiment> Fig. 1 is a cross-sectional view of a clutch device 10 according to this embodiment. The clutch device 10 is provided, for example, in a saddle-ride type 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, which is an example of a driving source of the motorcycle, to an output shaft 15. The clutch device 10 is a device that transmits or cuts off the rotational driving force of the input shaft to a driving wheel (rear wheel) via the output shaft 15. The clutch device 10 is disposed between the engine and a transmission.

[0016] In the following description, the direction in which the pressure member 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 member 70 approaches the clutch center 40 is referred to as a first direction D1, and the direction in which the pressure member 70 moves away from the clutch center 40 is referred to as a second direction D2. The circumferential direction (i.e., the rotational direction) of the clutch center 40 and the pressure member 70 is referred to as a circumferential direction S, the direction from one center-side cam portion 60 to the other center-side cam portion 60 with respect to the circumferential direction S (the direction from one pressure-side cam portion 90 to the other pressure-side cam portion 90) is referred to as a first circumferential direction S1 (see FIG. 2), and the direction from the other center-side cam portion 60 to one center-side cam portion 60 (the direction from the other pressure-side cam portion 90 to one pressure-side cam portion 90) is referred to as a second circumferential direction S2 (see FIG. 2). The radial direction of the output shaft 15 is referred to as the radial direction M, the direction away from the output shaft 15 as the outer side M1 (see FIG. 20), and the direction toward the output shaft 15 as the inner side M2 ​​(see FIG. 20). In this embodiment, the axial direction of the output shaft 15 is the same as direction D. The pressure member 70 and the clutch center 40 rotate in a first circumferential direction S1 (i.e., the direction from the center-side assist cam surface 60A of one center-side cam portion 60 toward the center-side slipper cam surface 60S). However, the above directions are merely defined for the convenience of explanation and do not limit the installation mode of the clutch device 10 or the present invention in any way.

[0017] As shown in FIG. 1, the clutch device 10 includes an output shaft 15, a plurality of input side rotating plates 20, a plurality of output side rotating plates 22, a clutch housing 30, a clutch center 40, a pressure member 70, a stopper plate 100, a centrifugal clutch mechanism 120, and an auxiliary clutch plate 180.

[0018] As shown in Figure 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 28A. The output shaft 15 fixedly supports a clutch center 40 via a nut 28B. 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.

[0019] As shown in Figure 1, the output shaft 15 has a main body 15A extending in direction D. The main body 15A has an oil flow path 15H therein through which clutch oil flows. The oil flow path 15H is formed between the main body 15A and a sleeve 16C that fits onto the outside of a push rod 16A (described later). The clutch oil flows inside the output shaft 15, i.e., through the oil flow path 15H of the main body 15A.

[0020] As shown in FIG. 1 , the oil flow path 15H of the output shaft 15 includes a push rod 16A and a push member 16B adjacent to the push rod 16A. The push rod 16A and the push member 16B are slidably disposed within a sleeve 16C. One end (the left end in the figure) of the push rod 16A is connected to a clutch operating lever (not shown) of the motorcycle. When the clutch operating lever is operated, the push rod 16A slides within the sleeve 16C 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 member 70. The sleeve 16C and the push member 16B are formed narrower than the inner diameter of the main body 15A, ensuring the flow of clutch oil within the oil flow path 15H.

[0021] The clutch housing 30 is formed by aluminum die-casting. The clutch housing 30 is formed in a cylindrical shape with a bottom. As shown in Figure 1, the clutch housing 30 has a bottom wall 31 formed in a substantially circular shape and a side wall 33 extending in the second direction D2 from an edge of the bottom wall 31. The clutch housing 30 holds a plurality of input side rotating plates 20.

[0022] 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 a rivet 35B via a torque damper 35A. The input gear 35 meshes with a drive gear (not shown) that rotates when the input shaft of the engine is rotated. The input gear 35 rotates integrally with the clutch housing 30, independently of the output shaft 15.

[0023] 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.

[0024] 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 material to retain clutch oil.

[0025] As shown in FIG. 1 , the clutch center 40 is accommodated in the clutch housing 30. The clutch center 40 is arranged concentrically with the clutch housing 30. The clutch center 40 holds a plurality of output side rotating plates 22. The output side rotating plates 22 and the input side rotating plates 20 are arranged alternately in direction D. The clutch center 40 is driven to rotate together with the output shaft 15. The clutch center 40 includes a first clutch center 41 and a second clutch center 51. The first clutch center 41 and the second clutch center 51 are assembled to each other. The second clutch center 51 is located outside M1 of the first clutch center 41 in the radial direction M. The second clutch center 51 is fitted onto the first clutch center 41.

[0026] As shown in Figure 2, the first clutch center 41 includes an output shaft holding portion 42, an annular base wall 43 located on the outer side M1 of the output shaft holding portion 42 in the radial direction M, and a plurality of center side cam portions 60.

[0027] As shown in Fig. 1, the output shaft 15 is connected to the output shaft holding portion 42. As shown in Fig. 2, the output shaft holding portion 42 is formed in a cylindrical shape. An insertion hole 45 into which the output shaft 15 is inserted and spline-fitted is formed in the output shaft holding portion 42. The insertion hole 45 is formed to penetrate the output shaft holding portion 42. A plurality of fitting teeth 47 extending in the axial direction of the output shaft 15 (i.e., direction D) are formed on an inner wall 45A of the output shaft holding portion 42 that defines the insertion hole 45. The fitting teeth 47 fit with the output shaft 15.

[0028] The center-side cam portion 60 is formed in a platform shape with 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 (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 decreases the pressing force (contact force) between the input-side rotating plate 20 and the output-side rotating plate 22, thereby transitioning to a partial clutch state. The partial clutch state is a state between a fully engaged state of the clutch (i.e., a state in which the input-side rotating plate 20 and the output-side rotating plate 22 are pressed against each other) and a fully disengaged state of the clutch (i.e., a state in which the input-side rotating plate 20 and the output-side rotating plate 22 are separated from each other). As shown in FIG. 2 , the center-side cam portion 60 is formed to protrude in the second direction D2 from a surface 43D2 on the second direction D2 side of the base wall 43. The center-side cam portions 60 are arranged at equal intervals in the circumferential direction S of the first clutch center 41. In this embodiment, the first clutch center 41 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. 2 , the center-side cam portion 60 is located on the outer side M1 of the output shaft holder 42 in the radial direction M. The center-side cam portion 60 has a center-side assist cam surface 60A (see also FIG. 3 ) 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) that moves the pressure member 70 toward the clutch center 40 when the pressure member 70 rotates relative to the pressure member 70 during acceleration or other such events 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 force is generated, the position of the pressure member 70 relative to the clutch center 40 does not change, and the pressure member 70 does not need to physically approach the clutch center 40. Note that the pressure member 70 may be physically displaced relative to the clutch center 40. The center-side slipper cam surface 60S is configured to move the pressure member 70 away from the clutch center 40 when it rotates relative to the pressure member 70 during deceleration, etc., 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 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 opposite each other in the circumferential direction S.

[0030] As shown in FIG. 2 , the first clutch center 41 has multiple boss portions 62 (three in this embodiment). The boss portions 62 are components that indirectly hold the pressure member 70. The multiple boss portions 62 are arranged at equal intervals in the circumferential direction S. The boss portions 62 are formed in a cylindrical shape. The boss portions 62 are located outwardly M1 in the radial direction M from the output shaft holding portion 42. The boss portions 62 extend toward the pressure member 70 (i.e., toward the second direction D2). The boss portions 62 are provided on the center-side cam portion 60. The boss portions 62 are provided between the center-side assist cam surface 60A and the center-side slipper cam surface 60S in the circumferential direction S. A threaded hole 62H is formed in the boss portion 62, into which the bolt 28 (see FIG. 1 ) is inserted. The threaded hole 62H extends in the axial direction of the clutch center 40 (i.e., in the direction D).

[0031] 2 and 3, the first clutch center 41 has a center-side cam hole 43H that penetrates a portion of the base wall 43. The center-side cam hole 43H penetrates the base wall 43 in direction D. The center-side cam hole 43H extends in the radial direction M from the side of the output shaft holding portion 42. The center-side cam hole 43H is located between adjacent center-side cam portions 60 in the circumferential direction S. When viewed axially of the clutch center 40, the center-side assist cam surface 60A and a portion of the center-side cam hole 43H overlap.

[0032] 2, the first clutch center 41 has a plurality of engagement grooves 49. The engagement grooves 49 are formed on the outer peripheral surface of the base wall 43. The engagement grooves 49 are recessed from the outer peripheral surface of the base wall 43 toward an inner side M2 ​​in the radial direction M.

[0033] 4, the second clutch center 51 includes an annular outer peripheral wall 52, a flange 68 extending from the outer peripheral wall 52 toward the outside M1 in the radial direction M, and a center-side fitting portion 54. The second clutch center 51 holds an input side rotating plate 20 and a plurality of output side rotating plates 22 arranged alternately in the direction D. The flange 68 is configured to be able to press the input side rotating plate 20 and the output side rotating plate 22.

[0034] As shown in FIG. 4 , a spline fitting portion 56 is provided on the outer peripheral surface of the outer peripheral wall 52. The spline fitting portion 56 has a plurality of center-side fitting teeth 57 extending along the outer peripheral surface of the outer peripheral wall 52 in the axial direction of the second clutch center 51 (i.e., direction D), a plurality of spline grooves 58 formed between adjacent center-side fitting teeth 57 and extending in the axial direction of the second clutch center 51 (i.e., direction D), and an oil discharge hole 59. The center-side fitting teeth 57 hold the output-side rotating plate 22. The center-side fitting teeth 57 are aligned in the circumferential direction S. The center-side fitting teeth 57 are formed at equal intervals in the circumferential direction S. The center-side fitting teeth 57 are formed with the same shape. The center-side fitting teeth 57 protrude from the outer peripheral surface of the outer peripheral wall 52 to the outside M1 in the radial direction M. The oil discharge hole 59 is formed to penetrate the outer peripheral wall 52 in the radial direction M. The oil discharge holes 59 are formed between adjacent center-side fitting teeth 57. That is, the oil discharge holes 59 are formed in the spline grooves 58. The oil discharge holes 59 are formed in the center-side fitting portion 54. The oil discharge holes 59 communicate between the inside and outside of the second clutch center 51. The oil discharge holes 59 are holes that discharge clutch oil and the like that has flowed into the clutch center 40 from the output shaft 15 to the outside of the clutch center 40. The clutch oil discharged from the oil discharge holes 59 is supplied to the input-side rotating plate 20 and the output-side rotating plate 22 that are located on the outside M1 of the oil discharge holes 59 in the radial direction M.

[0035] The output side rotating plate 22 is held by the spline fitting portion 56 of the second clutch center 51 and the pressure member 70. A portion of the output side rotating plate 22 is held by the center side fitting teeth 57 and the spline grooves 58 of the second clutch center 51 through spline fitting. Another portion of the output side rotating plate 22 is held by pressure side fitting teeth 87 (see FIG. 6 ) of the pressure member 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 (i.e., direction D). The output side rotating plate 22 is provided so as to be rotatable integrally with the clutch center 40. The output side rotating plate 22 is provided so as to be displaceable along the axial direction of the pressure member 70 (i.e., direction D). The output side rotating plate 22 is provided so as to be rotatable integrally with the pressure member 70.

[0036] 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 SPCC thin plate into an annular shape. 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.

[0037] As shown in Figure 4, the center-side fitting portion 54 is formed on the inner peripheral surface of the outer peripheral wall 52. The center-side fitting portion 54 is configured to slidably fit onto a pressure-side fitting portion 88 (see Figure 6), which will be described later. The inner diameter of the center-side fitting portion 54 is formed with a fitting tolerance that allows the flow of clutch oil flowing out from the tip end 15T (see Figure 1) of the output shaft 15 relative to the pressure-side fitting portion 88. In other words, a gap is formed between the center-side fitting portion 54 and the pressure-side fitting portion 88.

[0038] 4 and 5, the second clutch center 51 has a plurality of engagement protrusions 55. The engagement protrusions 55 engage with the engagement grooves 49 (see FIG. 2) of the first clutch center 41. The engagement protrusions 55 are formed on the inner circumferential surface of the outer circumferential wall 52. The engagement protrusions 55 protrude from the inner circumferential surface of the outer circumferential wall 52 toward the inner side M2 ​​in the radial direction M.

[0039] As shown in FIG. 1 , the pressure member 70 is provided so as to be able to move toward or away from the clutch center 40. The pressure member 70 is provided so as to be able to rotate relatively to the clutch center 40. The pressure member 70 is configured so as to be able to press the input side rotating plate 20 and the output side rotating plate 22. The pressure member 70 is arranged concentrically with the clutch center 40 and the clutch housing 30. The pressure member 70 is fitted into the second clutch center 51, thereby positioning the pressure member 70 in the radial direction M. The pressure member 70 is provided so as to be able to slide in direction D with respect to the first clutch center 41 and the second clutch center 51. The pressure member 70, the first clutch center 41, and the second clutch center 51 are configured so as to be able to rotate relatively to one another in the circumferential direction S. As shown in FIG. 6 , the pressure member 70 has a main body 72 and a flange 98 that connects to the outer peripheral edge of the main body 72 on the second direction D2 side and extends radially outward M1 in the radial direction M. 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 member 70. The flange 98 is located radially outward M1 beyond a cylindrical portion 80 (see also FIG. 7 ), which will be described later. The pressure member 70 holds at least a portion of the input side rotating plates 20 and the multiple output side rotating plates 22 that are arranged alternately. The flange 98 is configured to be able to press against the input side rotating plates 20 and the output side rotating plates 22.

[0040] As shown in FIG. 6, the main body 72 includes a cylindrical portion 80, a plurality of pressure-side cam portions 90, a pressure-side fitting portion 88, and a spring accommodating portion 84 (see FIG. 7).

[0041] 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 the pressing force from the push member 16B. The cylindrical portion 80 is a portion that receives the clutch oil that flows out from the tip portion 15T of the output shaft 15.

[0042] As shown in FIG. 6 , 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 to protrude in the first direction D1 beyond the flange 98. The pressure-side cam portions 90 are arranged at equal intervals in the circumferential direction S of the pressure member 70. In this embodiment, the pressure member 70 has three pressure-side cam portions 90, but the number of pressure-side cam portions 90 is not limited to three.

[0043] As shown in FIG. 6 , the pressure-side cam portion 90 is located radially outwardly M1 from the cylindrical portion 80. The pressure-side cam portion 90 has a pressure-side assist cam surface 90A (see also FIG. 7 ) 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 a direction from the pressure member 70 toward the clutch center 40 (here, the first direction D1) to increase the pressing force (pressure contact force) between the input-side rotating plate 20 and the output-side rotating plate 22 when the pressure member 70 rotates relative to the clutch center 40 during acceleration, etc. 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 move the pressure member 70 away from the clutch center 40 when the pressure member 70 rotates relative to the clutch center 40 during deceleration or the like 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 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 opposite each other in the circumferential direction S.

[0044] Here, the action of the center-side cam portion 60 and the pressure-side cam portion 90 will be described. When the engine speed increases and the rotational driving force input to the input gear 35 and the clutch housing 30 can be transmitted to the output shaft 15 via the clutch center 40, a rotational force in the first circumferential direction S1 is applied to the pressure member 70, as shown in Figure 8A. Therefore, due to the action of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, a force in the first direction D1 is generated in the pressure member 70, increasing the pressing force between the input-side rotating plate 20 and the output-side rotating plate 22.

[0045] On the other hand, when the rotational speed of the output shaft 15 exceeds the rotational speed of the input gear 35 and the clutch housing 30 and back torque is generated, a rotational force in the first circumferential direction S1 is applied to the clutch center 40, as shown in Fig. 8B. Therefore, the action of the center-side slipper cam surface 60S and the pressure-side slipper cam surface 90S moves the pressure member 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.

[0046] 6, the pressure-side fitting portion 88 is located on the outer side M1 in the radial direction M of the pressure-side cam portion 90. The pressure-side fitting portion 88 is located on the second direction D2 side of the pressure-side cam portion 90. The pressure-side fitting portion 88 is configured to be slidably fitted into the center-side fitting portion 54 (see FIG. 4).

[0047] As shown in FIGS. 6 and 7 , the pressure member 70 has a pressure-side cam hole 83H that penetrates a portion of the main body 72 and the flange 98. The pressure-side cam hole 83H is located on the outer side M1 of the cylindrical portion 80 in the radial direction M. The pressure-side cam hole 83H extends in the radial direction M from a side of the cylindrical portion 80 to the outer side M1 of the pressure-side fitting portion 88 in the radial direction M. The pressure-side cam hole 83H 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. When viewed in the axial direction of the pressure member 70, the pressure-side assist cam surface 90A and a portion of the pressure-side cam hole 83H overlap. The boss portion 62 (see FIG. 2 ) of the first clutch center 41 is inserted into the pressure-side cam hole 83H. The boss portion 62 passes through the pressure-side cam hole 83H.

[0048] As shown in FIG. 6 , the pressure member 70 has a plurality of pressure-side fitting teeth 87 arranged on a flange 98. The pressure-side fitting teeth 87 hold at least a portion of the output-side rotating plate 22. The pressure-side fitting teeth 87 protrude from the flange 98 in a first direction D1. The pressure-side fitting teeth 87 are located on the outer side M1 of the cylindrical portion 80 in the radial direction M. The pressure-side fitting teeth 87 are located on the outer side M1 of the pressure-side cam portion 90 in the radial direction M. The pressure-side fitting teeth 87 are located on the outer side M1 of the pressure-side fitting portion 88 in the radial direction M. The plurality of pressure-side fitting teeth 87 are aligned in the circumferential direction S. The plurality of pressure-side fitting teeth 87 are arranged at equal intervals in the circumferential direction S. In this embodiment, some of the pressure-side fitting teeth 87 have been removed, increasing the spacing between those portions, but the remaining adjacent pressure-side fitting teeth 87 are equally spaced. As shown in Fig. 1, the pressure-side fitting teeth 87 hold an end plate 21. The end plate 21 is a plate used to adjust the spacing in direction D between the input-side rotating plate 20 and the output-side rotating plate 22 (i.e., the spacing in the axial direction of the output shaft 15) when a weight member 130 (described later) of the centrifugal clutch mechanism 120 is at position PI on the inner side M2 ​​in the radial direction M.

[0049] As shown in Figure 7, the spring accommodating portion 84 is formed in the pressure-side cam portion 90. The spring accommodating portion 84 is located on the outer side M1 of the cylindrical portion 80 in the radial direction M. The spring accommodating portion 84 is formed so as to be recessed from the second direction D2 to the first direction D1. The spring accommodating portion 84 is formed in a circular shape. The spring accommodating portion 84 accommodates the clutch spring 25.

[0050] As shown in FIG. 1 , the clutch spring 25 is housed in the spring housing 84. An end 25D1 of the clutch spring 25 in the first direction D1 abuts against the pressure member 70. An end 25D2 of the clutch spring 25 in the second direction D2 abuts against the stopper plate 100. The clutch spring 25 biases the pressure member 70 toward the clutch center 40 (i.e., toward the first direction D1). The clutch spring 25 is, for example, a coil spring made of spring steel wound in a spiral shape. The clutch spring 25 extends in the direction D.

[0051] As shown in FIG. 1 , the centrifugal clutch mechanism 120 is provided within the clutch housing 30. The centrifugal clutch mechanism 120 is provided on the first direction D1 side of the clutch center 40. The centrifugal clutch mechanism 120 is held in the clutch housing 30. The centrifugal clutch mechanism 120 is provided to be rotatable integrally with the clutch housing 30. As shown in FIG. 9A , the centrifugal clutch mechanism 120 includes a plurality of weight members 130, a holding member 140, a pressure contact member 150 (see FIG. 1 ), a spring 160 (see also FIG. 9B ), and a contact member 170 (see also FIG. 1 ). When the weight members 130 are at a position PO on the outer side M1 in the radial direction M (see FIGS. 1 and 21 ), the centrifugal clutch mechanism 120 presses the input side rotating plate 20 and the output side rotating plate 22 together, thereby enabling transmission of the rotational driving force of the input shaft to the output shaft 15. When the weight member 130 is at a position PI on the inside M2 ​​in the radial direction M (see FIG. 20), the centrifugal clutch mechanism 120 releases the pressure contact force between the input side rotating plate 20 and the output side rotating plate 22, thereby enabling the transmission of the rotational driving force of the input shaft to the output shaft 15 to be blocked. The centrifugal clutch mechanism 120 is configured to be able to press the auxiliary clutch plate 180 (see FIG. 1).

[0052] As shown in Figure 9B, the holding member 140 holds the weight member 130 movably between a position PI on the inner side M2 ​​in the radial direction M and a position PO on the outer side M1 in the radial direction M (see Figure 18). The holding member 140 is formed in an annular shape. The holding member 140 is formed by aluminum die-casting. The holding member 140 includes a main body 141, a plurality of engaging claws 143, a plurality of accommodating recesses 145, and a pressing portion 149 (see Figure 1).

[0053] As shown in FIG. 10 , the main body 141 is formed in a ring shape. As shown in FIG. 12A , the main body 141 includes a thick portion 141T including a wall portion 141A and a protrusion 141B. The wall portion 141A is located between the engagement claw 143 and the accommodating recess 145 in the radial direction M. The protrusion 141B protrudes from the wall portion 141A toward the inner side M2 ​​in the radial direction M. The protrusion 141B defines a portion of the accommodating recess 145. An end portion 141BX of the protrusion 141B on the inner side M2 ​​in the radial direction M is located more inward M2 in the radial direction M than an end portion 145X of the accommodating recess 145 on the outer side M1 in the radial direction M. As shown in FIG. 9B , the protrusion 141B is located between a first spring 161 and a second spring 162 (described later) in the circumferential direction S. Note that a two-dot chain line 141EL in FIG. 12B indicates an outer peripheral edge 141E. 12B indicates a straight line that passes through an end 145X of the accommodating recess 145 on the outer side M1 in the radial direction M and is perpendicular to the radial direction M when viewed from the axial direction of the output shaft 15. In Fig. 12B, a dashed two-dot line 141BXL indicates a straight line that passes through an end 141BX of the protruding portion 141B on the inner side M2 ​​in the radial direction M and is perpendicular to the radial direction M when viewed from the axial direction of the output shaft 15.

[0054] As shown in Figure 10, the engagement claws 143 protrude from the outer peripheral edge 141E of the main body 141 toward the outer side M1 in the radial direction M. The engagement claws 143 are formed integrally with the main body 141. The engagement claws 143 engage with the clutch housing 30 (see Figure 1). The multiple engagement claws 143 are aligned in the circumferential direction S. As shown in Figure 12A, the engagement claws 143 have a head 143A and a root portion 143B located radially inward of the head 143A. The length LA of the head 143A in the circumferential direction S is longer than the length LB of the root portion 143B in the circumferential direction S.

[0055] As shown in FIG. 1 , the accommodating recess 145 is formed in the main body 141 so as to be recessed in the axial direction of the output shaft 15 (i.e., direction D). The accommodating recess 145 is recessed in a first direction D1. The accommodating recess 145 accommodates the weight member 130 so as to be movable in the radial direction M. The multiple accommodating recesses 145 are aligned in the circumferential direction S. As shown in FIGS. 10 and 11 , the accommodating recess 145 is provided with a sliding surface 145M along which the weight member 130 slides when the weight member 130 moves in the radial direction M. The accommodating recess 145 is formed with an accommodating groove 146 that accommodates a portion of the spring 160. The accommodating groove 146 extends in the radial direction M. The accommodating groove 146 includes a first accommodating groove 146A that accommodates a first spring 161 (described later) and a second accommodating groove 146B that accommodates a second spring 162. The first accommodating groove 146A is located closer to the first circumferential direction S1 than the protruding portion 141B. The second accommodating groove 146B is located closer to the second circumferential direction S2 than the protruding portion 141B. One end of each of the first spring 161 and the second spring 162 abuts against an end portion 145X on the outer side M1 in the radial direction M of the accommodating recess 145. As shown in FIG. 19 , the accommodating recess 145 is provided with a pressing surface 145H that is pressed by the weight member 130 when the weight member 130 is at a position PO on the outer side M1 in the radial direction M. A stress from the weight member 130 on the outer side M1 in the radial direction M is applied to the pressing surface 145H. The engaging claw 143 and the pressing surface 145H are positioned offset from each other in the circumferential direction S. Here, the engaging claw 143 is positioned between the pair of pressing surfaces 145H in the circumferential direction S. The accommodating recess 145 may be formed with a through-hole that penetrates the main body 141 in the axial direction of the output shaft 15 (i.e., direction D). In this case, the clutch oil flowing outside the holding member 140 flows into the accommodating recess 145 via the through-hole.

[0056] As shown in FIG. 12A , the length L1 of the protrusion 141B in the circumferential direction S is equal to or greater than the length L2 of the engagement claw 143 in the circumferential direction S. The length L3 in the radial direction M from the outer peripheral edge 141E of the main body 141 to the end 141BX of the protrusion 141B on the inner side M2 ​​in the radial direction M is longer than the length L4 in the radial direction M from the outer peripheral edge 141E of the main body 141 to the end 143X of the engagement claw 143 on the outer side M1 in the radial direction M. The end 141BL in the first circumferential direction S1 of the protrusion 141B is located closer to the first circumferential direction S1 than the end 143AL in the first circumferential direction S1 of the engagement claw 143. Here, the end 143AL in the first circumferential direction S1 of the engagement claw 143 is the end of the head 143A in the first circumferential direction S1. An end 141BR of the protrusion 141B in the second circumferential direction S2 is located closer to the second circumferential direction S2 than an end 143AR of the engagement claw 143 in the second circumferential direction S2. Here, the end 143AR of the engagement claw 143 in the second circumferential direction S2 is the end of the head 143A in the second circumferential direction S2. Furthermore, an end 141BL of the protrusion 141B in the first circumferential direction S1 is located closer to the first circumferential direction S1 than an end 143BL of the root 143B in the first circumferential direction S1. An end 141BR of the protrusion 141B in the second circumferential direction S2 is located closer to the second circumferential direction S2 than an end 143BR of the root 143B in the second circumferential direction S2. The surfaces of the wall 141A, the protrusion 141B, and the engagement claw 143 facing the pressure contact member 150 are flush with each other. 12B indicates a straight line that passes through an end 143X on the outer side M1 of the engagement claw 143 in the radial direction M and is perpendicular to the radial direction M when viewed from the axial direction of the output shaft 15. A two-dot chain line 141BLL in FIG. 12B indicates a straight line that passes through an end 141BL of the protrusion 141B in the first circumferential direction S1 and is parallel to the radial direction M when viewed from the axial direction of the output shaft 15. A two-dot chain line 143ALL in FIG. 12B indicates a straight line that passes through an end 143AL of the engagement claw 143 in the first circumferential direction S1 and is parallel to the radial direction M when viewed from the axial direction of the output shaft 15. A two-dot chain line 143BLL in FIG. 12B indicates a straight line that passes through an end 143BL of the root portion 143B in the first circumferential direction S1 and is parallel to the radial direction M when viewed from the axial direction of the output shaft 15. 12B indicates a straight line that passes through the end 141BR of the protrusion 141B in the second circumferential direction S2 and is parallel to the radial direction M when viewed from the axial direction of the output shaft 15.12B indicates a straight line that passes through the end 143AR of the engagement claw 143 in the second circumferential direction S2 and is parallel to the radial direction M when viewed in the axial direction of the output shaft 15. In FIG. 12B, a dashed two-dot line 143BRL indicates a straight line that passes through the end 143BR of the root portion 143B in the second circumferential direction S2 and is parallel to the radial direction M when viewed in the axial direction of the output shaft 15.

[0057] As shown in FIG. 9B , the multiple weight members 130 are arranged in the circumferential direction S. The weight members 130 are configured to be movable from a position PI on the inner side M2 ​​in the radial direction M to a position on the outer side due to centrifugal force generated by rotation of the clutch housing 30. The weight members 130 are configured to be able to press the pressing member 150 in the second direction D2. As shown in FIG. 20 , when no centrifugal force is applied, the weight members 130 are held at a position PI on the inner side M2 ​​in the radial direction M by a spring 160 (see FIG. 9B ). As shown in FIG. 21 , when centrifugal force is applied, the weight members 130 move toward the outer side M1 in the radial direction M against the biasing force of the spring 160, and move to a position PO on the outer side M1 in the radial direction M. At this time, as shown in FIG. 19 , the weight member 130 presses the pressing surface 145H of the accommodation recess 145, but does not come into contact with the protrusion 141B of the holding member 140. The weight member 130 is accommodated in the accommodation recess 145 of the holding member 140. As shown in FIG. 15 , the weight member 130 includes a biasing member holding portion 131, a first flat surface 133 provided on one side of the biasing member holding portion 131 in the circumferential direction S, a second flat surface 135 provided on the other side of the biasing member holding portion 131 in the circumferential direction S, and a weight-side inclined surface 130F (see FIG. 13 ) located on the opposite side of the first flat surface 133 and the second flat surface 135 in the axial direction of the output shaft 15 (i.e., direction D). The weight-side inclined surface 130F is an example of a weight-side sliding portion.

[0058] The biasing member holding portion 131 holds the spring 160. As shown in Fig. 15, the biasing member holding portion 131 is a recessed groove recessed from the first direction D1 to the second direction D2 and from the outer side M1 to the inner side M2 ​​in the radial direction M. The biasing member holding portion 131 includes a holding wall 132 that holds the end of the spring 160 on the inner side M2 ​​in the radial direction M. In this embodiment, the biasing member holding portion 131 includes a first biasing member holding portion 131A that holds a first spring 161 (described later) and a second biasing member holding portion 131B that holds a second spring 162 (described later).

[0059] As shown in FIGS. 15 and 16 , the first flat surface 133 is located closer to the first circumferential direction S1 than the biasing member holding portion 131. More specifically, the first flat surface 133 is located closer to the first circumferential direction S1 than the first biasing member holding portion 131A. The first flat surface 133 is arranged side by side with the first biasing member holding portion 131A in the circumferential direction. The second flat surface 135 is located closer to the second circumferential direction S2 than the biasing member holding portion 131. More specifically, the second flat surface 135 is located closer to the second circumferential direction S2 than the second biasing member holding portion 131B. The second flat surface 135 is arranged side by side with the second biasing member holding portion 131B in the circumferential direction. As shown in FIG. 17 , the first flat surface 133 and the second flat surface 135 are perpendicular to the axial direction (i.e., direction D) of the output shaft 15. The first flat surface 133 and the second flat surface 135 are formed flush with each other. The first flat surface 133 and the second flat surface 135 are provided to be slidable relative to the holding member 140. More specifically, the first flat surface 133 and the second flat surface 135 are provided to be slidable relative to a sliding surface 145M of the accommodating recess 145. As shown in Fig. 16 , an end portion 133A on the inner side M2 ​​in the radial direction M of the first flat surface 133 and an end portion 135A on the inner side M2 ​​in the radial direction M of the second flat surface 135 are located on the inner side M2 ​​in the radial direction M than the holding wall 132.

[0060] 15 , the weight member 130 has a third flat surface 137. The third flat surface 137 is located between the first flat surface 133 and the second flat surface 135 in the circumferential direction S. The third flat surface 137 is located between the first biasing member holding portion 131A and the second biasing member holding portion 131B in the circumferential direction S. The third flat surface 137 may be provided to be slidable relative to the holding member 140. The third flat surface 137 may be formed flush with the first flat surface 133 and the second flat surface 135.

[0061] The weight-side inclined surface 130F is provided so as to be able to come into contact with the pressing member 150. As shown in Figure 17, the weight-side inclined surface 130F is inclined with respect to the axial direction of the output shaft 15 (i.e., direction D). The weight-side inclined surface 130F is inclined so as to face in a first direction D1 from an inner side M2 ​​in the radial direction M to an outer side M1 in the radial direction M. The weight-side inclined surface 130F is configured so as to be able to slide against a later-described pressing-side inclined surface 150F (see Figure 20) of the pressing member 150.

[0062] As shown in FIG. 17 , an end portion 133B on the outer side M1 of the first flat surface 133 and an end portion 135B on the outer side M1 of the second flat surface 135 are located further outward in the radial direction M than an end portion 130FA on the inner side M2 ​​of the weight-side inclined surface 130F. An end portion 133A on the inner side M2 ​​of the first flat surface 133 and an end portion 135A on the inner side M2 ​​of the second flat surface 135 are located further inward in the radial direction M than an end portion 130FA on the inner side M2 ​​of the weight-side inclined surface 130F. A length L5 in the radial direction M of the first flat surface 133 and the second flat surface 135 is longer than a length L6 in the radial direction M of the weight-side inclined surface 130F. The total area of ​​the first flat surface 133 and the second flat surface 135 is greater than the area of ​​the weight-side inclined surface 130F. The length L7 (see Figure 16) in the circumferential direction S from the end 133S1 in the first circumferential direction S1 of the first plane 133 to the end 135S2 in the second circumferential direction S2 of the second plane 135 is longer than the length L8 (see Figure 14) in the circumferential direction S of the weight-side inclined surface 130F.

[0063] As shown in FIG. 9B , the spring 160 is disposed on the outer side M1 of the weight member 130 in the radial direction M. The spring 160 is an example of a biasing member. The spring 160 is provided in the holding member 140. The spring 160 is housed in the housing recess 145 of the holding member 140. More specifically, a portion of the spring 160 is housed in the housing groove 146 (see FIG. 10 ). A portion of the spring 160 is located inside the weight member 130. That is, a portion of the spring 160 is located in the biasing member holding portion 131. The spring 160 biases the weight member 130 toward the inner side M2 ​​in the radial direction M. The spring 160 is, for example, a coil spring. The spring 160 includes a first spring 161 and a second spring 162 arranged side by side in the circumferential direction S. The first spring 161 is an example of a first biasing member. The second spring 162 is an example of a second biasing member. The first spring 161 and the second spring 162 have the same shape. The first spring 161 and the second spring 162 are housed in the housing recess 145. The first spring 161 and the second spring 162 bias the weight member 130 toward the inner side M2 ​​in the radial direction M. The first spring 161 and the second spring 162 are provided between the first plane 133 and the second plane 135 in the circumferential direction S.

[0064] As shown in FIG. 1 , the contact member 170 is disposed between the holding member 140 and the pressure contact member 150. The contact member 170 is disposed on the opposite side of the holding member 140 with the weight member 130 sandwiched between them in the axial direction (direction D in this case) of the output shaft 15. As shown in FIG. 9A , the contact member 170 is formed in a disk shape. The contact member 170 is fixed to the holding member 140. More specifically, the contact member 170 is fixed to the holding member 140 by fastening bolts 172 into bolt holes 140H (see FIG. 9B ) formed in the holding member 140. Note that the means for fixing the contact member 170 to the holding member 140 is not limited to the bolts 172. Instead of the bolts 172, the contact member 170 may be fixed to the holding member 140 by other fixing means, such as rivets. The contact member 170 comes into contact with the weight member 130. The contact member 170 is a member that suppresses movement of the weight member 130 in the second direction D2. The contact member 170 has a plurality of openings 170H that are aligned in the circumferential direction S. The weight-side inclined surface 130F of the weight member 130 is exposed to the outside through the openings 170H.

[0065] The pressing member 150 is configured to be able to move in the axial direction of the output shaft 15 (here, in the second direction D2) as the weight member 130 moves from a position PI on the inner side M2 ​​in the radial direction M to a position PO on the outer side M1, thereby pressing the input side rotating plate 20 and the output side rotating plate 22 together. The pressing member 150 is formed in an annular shape. As shown in FIG. 1 , the pressing member 150 has a pressing-side inclined surface 150F and a pressing surface 150P. The pressing-side inclined surface 150F is an example of a pressing-side sliding portion. The pressing-side inclined surface 150F is provided so as to be able to come into contact with the weight member 130. The pressing-side inclined surface 150F is inclined with respect to the axial direction of the output shaft 15 (i.e., direction D). The pressing-side inclined surface 150F is inclined in a first direction D1 from the inner side M2 ​​in the radial direction M toward the outer side M1 in the radial direction M. The pressure-side inclined surface 150F is configured to be slidable relative to the weight-side inclined surface 130F of the weight member 130. As shown in FIG. 21 , in a cross-sectional view taken along a plane including the axial direction (i.e., direction D) and radial direction M of the output shaft 15, a straight line CL1 passing through a center 150FC of the pressure-side inclined surface 150F in the radial direction M and parallel to the axial direction (i.e., direction D) of the output shaft 15 passes through the first flat surface 133 and the second flat surface 135 when the weight member 130 is positioned on the outer side M1 in the radial direction M. A plurality of pressure-side inclined surfaces 150F are provided for each weight member 130 along the circumferential direction S. When the clutch housing 30 rotates and centrifugal force is applied to the weight member 130, the weight member 130 moves along the pressure-side inclined surface 150F, causing the pressure member 150 to move in a direction away from the holding member 140 (i.e., the second direction D2). As a result, the pressing surface 150P of the pressure contact member 150 presses the flange 68 of the second clutch center 51 in the second direction D2. The pressure contact member 150 has a plurality of engaging protrusions 153 formed in the circumferential direction S. The engaging protrusions 153 overlap with the engaging claws 143 of the holding member 140. The engaging protrusions 153 engage with the clutch housing 30. The holding member 140 and the pressure contact member 150 are held in the clutch housing 30 by spline fitting. The holding member 140 and the pressure contact member 150 are provided so as to be displaceable along the axial direction of the clutch housing 30 (i.e., direction D).The holding member 140 and the pressure contact member 150 are provided so as to be rotatable integrally with the clutch housing 30 .

[0066] 9A and 20 , when no centrifugal force is applied to the weight member 130, the weight member 130 is held at position PI on the inner side M2 ​​in the radial direction M, and the pressing force between the input side rotating plate 20 and the output side rotating plate 22 is released. On the other hand, as shown in FIGS. 18 and 21 , when centrifugal force is applied to the weight member 130, the weight member 130 moves from position PI on the inner side M2 ​​to position PO on the outer side M1 in the radial direction M. When the weight member 130 moves in the radial direction M, the weight-side inclined surface 130F of the weight member 130 slides against the pressing-side inclined surface 150F of the pressing member 150, and the first flat surface 133 and the second flat surface 135 of the weight member 130 slide against the sliding surface 145M of the holding member 140. At this time, the pressing surface 150P of the pressing member 150 presses the input side rotating plate 20 and the output side rotating plate 22 via the flange 68 of the second clutch center 51, bringing them into a pressed state, and the rotational driving force of the input shaft becomes capable of being transmitted to the output shaft 15. At the same time, the holding member 140 moves in the first direction D1, and the pressing portion 149 (see FIG. 1) of the holding member 140 presses the auxiliary clutch plate 180.

[0067] As shown in Fig. 1, the auxiliary clutch plate 180 is provided inside the clutch housing 30. The auxiliary clutch plate 180 is fixed to the output shaft 15. An insertion hole 152H is formed in the auxiliary clutch plate 180, into which the output shaft 15 is inserted and spline-fitted. The auxiliary clutch plate 180 is disposed closer to the first direction D1 than a portion of the centrifugal clutch mechanism 120. The auxiliary clutch plate 180 is adjacent to the first clutch center 41.

[0068] The auxiliary clutch plate 180 is configured to be pressed by the centrifugal clutch mechanism 120 (here, the pressing portion 149 of the holding member 140) when the input side rotating plate 20 and the output side rotating plate 22 are in pressure contact with each other (i.e., when the weight member 130 of the centrifugal clutch mechanism 120 is located at position PO on the outer side M1 in the radial direction M), thereby enabling the rotational driving force of the input shaft to be transmitted to the output shaft 15. The auxiliary clutch plate 180 is configured to be released from the pressure of the centrifugal clutch mechanism 120 (here, the pressing portion 149 of the holding member 140) when the pressure contact force between the input side rotating plate 20 and the output side rotating plate 22 is released (i.e., when the weight member 130 is located at position PI on the inner side M2 ​​in the radial direction M), thereby blocking the transmission of the rotational driving force of the input shaft to the output shaft 15.

[0069] As shown in Fig. 1, the stopper plate 100 is provided so as to be able to come into contact with the pressure member 70. The stopper plate 100 is a member that prevents the pressure member 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 boss portion 62 of the first clutch center 41 by the bolt 28. With the clutch spring 25 disposed in the spring accommodating portion 84, the pressure member 70 is fixed to the clutch center 40 by tightening the bolt 28 to the boss portion 62 via the stopper plate 100. The stopper plate 100 is formed in a ring shape in a plan view.

[0070] As described above, in the clutch device 10 of this embodiment, the main body 141 of the retaining member 140 includes a thick portion 141T that includes a wall portion 141A located between the engagement claw 143 and the accommodating recess 145 in the radial direction M, and a protrusion 141B that protrudes from the wall portion 141A toward the inner side M2 ​​in the radial direction M and defines a part of the accommodating recess 145. According to the above aspect, the thick portion 141T is provided between the engagement claw 143 and the accommodating recess 145, and therefore the thickness in the radial direction M is increased by the amount of the thick portion 141T, thereby increasing the rigidity of the engagement claw 143. As a result, even if the weight member 130 comes into contact with the protrusion 141B, for example, the rigidity of the engagement claw 143 is improved, thereby preventing damage to the engagement claw 143.

[0071] In the clutch device 10 of this embodiment, the length L1 of the protrusion 141B in the circumferential direction S is equal to or greater than the length L2 of the engagement claw 143 in the circumferential direction S. According to the above aspect, the rigidity of the engagement claw 143 can be further increased.

[0072] In the clutch device 10 of this embodiment, the length L3 in the radial direction M from the outer peripheral edge 141E of the main body 141 to the end 141BX on the inner side M2 ​​in the radial direction M of the protrusion 141B is longer than the length L4 in the radial direction M from the outer peripheral edge 141E of the main body 141 to the end 143X on the outer side M1 in the radial direction M of the engagement claw 143. According to the above aspect, the rigidity of the engagement claw 143 can be further increased.

[0073] In the clutch device 10 of this embodiment, the protrusion 141B is located between the first spring 161 and the second spring 162 in the circumferential direction S. According to the above aspect, the load applied to the engagement pawl 143 from the weight member 130 can be reduced.

[0074] 22 , a centrifugal clutch mechanism 220 according to the second embodiment includes a plurality of weight members 230, a holding member 240, a pressure contact member 150, a spring 160 (see FIG. 25 ), and a cylindrical member 270. The centrifugal clutch mechanism 220 has the same configuration as the centrifugal clutch mechanism 120 according to the first embodiment, except that it includes weight members 230 instead of weight members 130, holds holding members 240 instead of holding members 140, and further includes a cylindrical member 270.

[0075] As shown in Figures 22 and 23, the holding member 240 includes a holding member-side guide portion 245 that accommodates a portion of the cylindrical member 270. The holding member-side guide portion 245 is formed on a surface 245M of the accommodating recess 145 that faces the weight member 230. The holding member-side guide portion 245 holds the cylindrical member 270 so that a portion of the cylindrical member 270 protrudes from the surface 245M of the holding member 240 that faces the weight member 230 toward the weight member 230 (i.e., toward the second direction D2). The holding member-side guide portion 245 guides movement of the cylindrical member 270 in the radial direction M. The holding member-side guide portion 245 is located between the first accommodating groove 146A and the second accommodating groove 146B in the circumferential direction S. The holding member-side guide portion 245 is rectangular in plan view. The holding member side guide portion 245 is configured to restrict the cylindrical member 270 from moving in the circumferential direction S, and also restrict the cylindrical member 270 from moving in the radial direction M more than a predetermined distance.

[0076] As shown in FIG. 24 , the weight member 230 includes a guide portion 238 that accommodates a portion of the cylindrical member 270. The guide portion 238 is formed on a surface (here, the third flat surface 137) facing the holding member 240. The guide portion 238 holds the cylindrical member 270 so that a portion of the cylindrical member 270 protrudes from the surface (here, the third flat surface 137) of the weight member 230 facing the holding member 240 toward the holding member 240 (i.e., toward the first direction D1) (see FIG. 26 ). The guide portion 238 guides the movement of the cylindrical member 270 in the radial direction M. The guide portion 238 is located between the first biasing member holding portion 131A and the second biasing member holding portion 131B with respect to the circumferential direction S. As shown in FIG. 25 , the guide portion 238 is formed in a rectangular shape in a plan view. The guide portion 238 includes a first restricting portion 238S that restricts movement of the cylindrical member 270 in the circumferential direction S and a second restricting portion 238M that restricts movement of the cylindrical member 270 in the radial direction M beyond a predetermined distance. The first restricting portion 238S is provided on each of the first circumferential direction S1 side and the second circumferential direction S2 side with respect to the circumferential direction S. The second restricting portion 238M is provided on each of the outer side M1 and the inner side M2 ​​with respect to the radial direction M. The guide portion 238 has an accommodation groove 238P that is recessed in a direction from the retaining member 240 toward the weight member 230 (i.e., the second direction D2) with respect to the axial direction of the output shaft 15 (i.e., direction D) and accommodates a portion of the cylindrical member 270. The accommodation groove 238P is defined by the first restricting portion 238S and the second restricting portion 238M.

[0077] As shown in FIG. 22 , the cylindrical member 270 is provided between the weight member 230 and the holding member 240 in the axial direction of the output shaft 15 (i.e., direction D). The cylindrical member 270 is disposed to extend in a direction intersecting the radial direction M (here, a direction perpendicular to the radial direction M and direction D). The cylindrical member 270 rolls relative to the weight member 230 and the holding member 240. A portion of the cylindrical member 270 is housed in the holding member-side guide portion 245 of the holding member 240, and another portion of the cylindrical member 270 is housed in the guide portion 238 of the weight member 230. The cylindrical member 270 rolls relative to the holding member-side guide portion 245 and the guide portion 238. As shown in FIG. 25 , the cylindrical member 270 is located between the first spring 161 and the second spring 162 in the circumferential direction S. The length L9 of the cylindrical member 270 in the circumferential direction S is equal to or greater than one-fourth of the length L8 (see FIG. 14) of the weight-side inclined surface 130F in the circumferential direction S.

[0078] 27 , in a cross-sectional view taken along a plane including the axial direction (i.e., direction D) and the radial direction M of the output shaft 15, when the weight member 230 is positioned on the inner side M2 ​​in the radial direction M, at least a portion of the cylindrical member 270 overlaps with the spring 160. In this case, the entire cylindrical member 270 overlaps with the spring 160. In a cross-sectional view taken along a plane including the axial direction (i.e., direction D) and the radial direction M of the output shaft 15, when the weight member 230 is positioned on the inner side M2 ​​in the radial direction M, at least a portion of the guide portion 238 overlaps with the spring 160. In this case, the entire guide portion 238 overlaps with the spring 160.

[0079] As shown in Figure 28 , in a cross-sectional view taken along a plane including the axial direction (i.e., direction D) and radial direction M of the output shaft 15, a straight line CL2 passing through the center 150FC of the pressure-contact-side inclined surface 150F in the radial direction M and parallel to the axial direction (i.e., direction D) of the output shaft 15 passes through the guide portion 238 when the weight member 230 is positioned on the outer side M1 in the radial direction M. As shown in Figure 29 , when viewed from the axial direction (i.e., direction D) of the output shaft 15 with the weight member 230 positioned on the inner side M2 ​​in the radial direction M, at least a portion of the weight-side inclined surface 130F overlaps with the holding member-side guide portion 245. As shown in Figure 30 , when viewed from the axial direction (i.e., direction D) of the output shaft 15 with the weight member 230 positioned on the outer side M1 in the radial direction M, at least a portion of the pressure-contact-side inclined surface 150F overlaps with the guide portion 238.

[0080] In this centrifugal clutch mechanism 220, as shown in Figures 27 and 29, when no centrifugal force is applied to the weight member 230, the weight member 230 is held at position PI on the inner side M2 ​​in the radial direction M, and the pressure contact force between the input side rotating plate 20 and the output side rotating plate 22 is released. On the other hand, as shown in Figures 28 and 30, when centrifugal force is applied to the weight member 230, the weight member 230 moves from position PI on the inner side M2 ​​in the radial direction M to position PO on the outer side M1. When the weight member 230 moves in the radial direction M, the cylindrical member 270 rolls relative to the weight member 230 and the holding member 240, guided by the guide portion 238 and the holding member side guide portion 245. At this time, the first flat surface 133 and the second flat surface 135 of the weight member 230 do not slide on the sliding surface 145M of the holding member 240.

[0081] <Third embodiment> As shown in Figure 31, a holding member 340 according to the third embodiment includes a main body 341, a plurality of engaging claws 143, a plurality of accommodating recesses 345, and a pressing portion 149 (see Figure 1).

[0082] The main body 341 is formed in a ring shape. As shown in Fig. 31 , the main body 341 includes a wall portion 341A. The wall portion 341A is located between the engagement claw 143 and the accommodating recess 345 in the radial direction M. The wall portion 341A defines a part of the accommodating recess 345.

[0083] 31 , the accommodating recess 345 is formed in the main body 341 so as to be recessed in the axial direction of the output shaft 15. The accommodating recess 345 is recessed in a first direction D1. The accommodating recess 345 accommodates the weight member 130 so as to be movable in the radial direction M. An end portion 345X of the accommodating recess 345 on the outer side M1 in the radial direction M abuts one end of each of the first spring 161 and the second spring 162.

[0084] 31 , the length L10 of the wall portion 341A in the radial direction M is longer than the length L4 in the radial direction M from the outer peripheral edge 141E of the main body 341 to the end 143X on the outer side M1 in the radial direction M of the engagement claw 143. Here, the length L10 in the radial direction M of the wall portion 341A is the length in the radial direction M from the outer peripheral edge 141E of the main body 341 to the end 345X on the outer side M1 in the radial direction M of the accommodating recess 345. The length L11 in the circumferential direction S of the wall portion 341A is equal to or longer than the length L2 of the engagement claw 143 in the circumferential direction S.

[0085] According to the clutch device 10 of this embodiment, the main body 341 of the retaining member 340 includes a wall portion 341A located between the engagement claw 143 and the accommodating recess 345 in the radial direction M, and the length L10 of the wall portion 341A in the radial direction M is longer than the length L4 in the radial direction M from the outer peripheral edge 141E of the main body 341 to the end 143X of the engagement claw 143 on the outer side M1 in the radial direction M. According to the above aspect, the wall portion 341A is relatively thick, which increases the rigidity of the engagement claw 143. As a result, even if the weight member 130 comes into contact with the wall portion 341A, the increased rigidity of the engagement claw 143 can prevent damage to the engagement claw 143.

[0086] In the clutch device 10 of this embodiment, the length L11 of the wall portion 341A in the circumferential direction S is equal to or greater than the length L2 of the engagement claw 143 in the circumferential direction S. According to the above aspect, the rigidity of the engagement claw 143 can be further increased. Fourth Embodiment FIG. 32 is a plan view showing a portion of a centrifugal clutch mechanism 420 according to a fourth embodiment. The centrifugal clutch mechanism 420 includes a plurality of weight members 130, a holding member 140, a pressure contact member 150 (see FIG. 1), a spring 160, and a contact member 170 (see FIG. 1). The plurality of weight members 130 include a first weight member 130A and a second weight member 130B. The first weight member 130A and the second weight member 130B have the same configuration, except that the first weight member 130A is lighter than the second weight member 130B. The first weight member 130A and the second weight member 130B are formed of, for example, different materials. In the example shown in Fig. 1, the first weight member 130A and the second weight member 130B are configured to move the pressing member 150 in the second direction D2.

[0087] As shown in FIG. 32 , the first weight members 130A and the second weight members 130B are alternately arranged in the circumferential direction S. That is, one first weight member 130A is located between two second weight members 130B that are aligned in the circumferential direction S. The number of first weight members 130A is the same as the number of second weight members 130B. In this embodiment, there are three first weight members 130A and three second weight members 130B, but the number of each is not limited to three. When viewed in the axial direction of the output shaft 15, some of the multiple first weight members 130A are arranged line-symmetrically with respect to a line LC that passes through the center 15C of the output shaft 15, and some of the multiple second weight members 130B are arranged line-symmetrically with respect to the line LC.

[0088] As shown in FIGS. 33A and 33B , the first weight member 130A starts moving from a position PI on the inner side M2 ​​in the radial direction M toward a position PO on the outer side M1 in the radial direction M when the engine speed is a first rotational speed E1. The first rotational speed E1 is the engine speed when the vehicle starts moving. When the engine speed is the first rotational speed E1, the first weight member 130A starts pressing the pressing member 150, moving the pressing member 150 in the axial direction (i.e., direction D). The pressing member 150 starts moving from a position PD1 closest to the first direction D1, which is its initial position, toward a position PD2 closest to the second direction D2. Until the engine speed reaches the second rotational speed E2 from the first rotational speed E1, the first weight member 130A continues moving in the radial direction M, and the pressing member 150 continues moving in the second direction D2. In the half-clutch state, the second weight member 130B starts moving from a position PI on the inner side M2 ​​in the radial direction M toward a position PO on the outer side M1 in the radial direction M. The engine speed in the half-clutch state is higher than the engine speed when the vehicle starts (here, the first rotation speed E1). For example, when the engine speed is the second rotation speed E2, the second weight member 130B starts moving from a position PI on the inner side M2 ​​in the radial direction M toward a position PO on the outer side M1 in the radial direction M. During the period from the second rotation speed E2 to the third rotation speed E3, the first weight member 130A does not move in the radial direction M, the pressing member 150 does not move in the direction D, and only the second weight member 130B continues to move in the radial direction M. The second weight member 130B begins to press against the pressing member 150 when the engine rotation speed is a third rotation speed E3, causing the pressing member 150 to move in the axial direction (i.e., direction D). When the engine rotation speed is the third rotation speed E3, the first weight member 130A and the second weight member 130B begin to press against the pressing member 150 simultaneously, causing the pressing member 150 to start moving in direction D again. Thereafter, the first weight member 130A and the second weight member 130B reach position PO on the outer side M1 in the radial direction M when the engine rotation speed is a sixth rotation speed E6. At this time, the pressing member 150 also reaches position PD2.In this way, since the first weight member 130A and the second weight member 130B are not all used to press the pressing member 150 from the beginning, the input side rotating plate 20 and the output side rotating plate 22 are gradually pressed together rather than suddenly. In other words, sudden clutch engagement can be suppressed, thereby suppressing a deterioration in ride comfort. In this embodiment, the first movement amount MD1 of the first weight member 130A in the radial direction M while the engine speed is increasing from the first rotational speed E1 to the second rotational speed E2 is different from the second movement amount MD2 of the first weight member 130A in the radial direction M while the engine speed is increasing from the second rotational speed E2 to the sixth rotational speed E6. Here, the second movement amount MD2 is greater than the first movement amount MD1. 33A and 33B, E0 is the engine speed during idling, E4 is the engine speed at which the action of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A begins to generate a force in the direction from the pressure member 70 toward the clutch center 40 (here, the first direction D1), and E5 is the engine speed at which the input-side rotating plate 20 and the output-side rotating plate 22 are fully pressed together. The center-side assist cam surface 60A and the pressure-side assist cam surface 90A are configured to begin generating a force in the direction from the pressure member 70 toward the clutch center 40 when the engine speed is the fourth rotational speed E4. Also, in Figure 33A, the solid line indicates the trajectory of movement of the first weight member 130A, the dashed line indicates the trajectory of movement of the second weight member 130B, and the dotted line indicates the trajectories of movement of the first weight member 130A and the second weight member 130B.

[0089] 33A and 33B , the pressing member 150 does not move in direction D (here, second direction D2) while the engine rotation speed reaches from the second rotation speed E2 to the third rotation speed E3, but may move continuously in direction D as the engine rotation speed increases. For example, while the engine rotation speed reaches from the second rotation speed E2 to the third rotation speed E3, the first weight member 130A and the second weight member 130B may move in the radial direction M, and the pressing member 150 may move in direction D. In this case, for example, the first weight member 130A and the second weight member 130B may start to press the pressing member 150 simultaneously when the engine rotation speed reaches the second rotation speed E2. Furthermore, in the example of Figure 33A, when the engine speed is the third rotation speed E3 which is lower than the fourth rotation speed E4, the first weight member 130A and the second weight member 130B begin to press the pressing member 150 simultaneously, but the first weight member 130A and the second weight member 130B may also begin to press the pressing member 150 simultaneously at a rotation speed higher than the fourth rotation speed E4. That is, at rotation speeds lower than the fourth rotation speed E4 when a force begins to be generated in the direction from the pressure member 70 toward the clutch center 40 (here, the first direction D1) due to the action of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, only the first weight member 130A, which is a part of the weight member 130, presses the pressing member 150, and the second weight member 130B, which is another part of the weight member 130, does not press the pressing member 150. In other words, the third rotation speed E3, which is the upper limit of a first region RE1 described later, may be set to a rotation speed higher than the fourth rotation speed E4. As a result, when a force begins to be generated in the direction from the pressure member 70 toward the clutch center 40 due to the action of the center side assist cam surface 60A and the pressure side assist cam surface 90A, the input side rotating plate 20 and the output side rotating plate 22 are gradually pressed together only by the first weight member 130A, thereby preventing sudden engagement of the clutch and preventing a decrease in ride comfort.

[0090] 33A and 33B , when the engine speed is in the first region RE1, some of the weight members 130 (here, the first weight member 130A) press against the pressing member 150, and when the engine speed is in the second region RE2, all of the weight members 130 (here, the first weight member 130A and the second weight member 130B) press against the pressing member 150. Here, the pressing of the pressing member 150 includes a case where the pressing member 150 presses against the pressing member 150, causing it to move in the second direction D2, and a case where the pressing member 150 presses against the pressing member 150 but does not move in the second direction D2. The first region RE1 is from the engine speed at the time of starting the vehicle (e.g., the first rotational speed E1) to a predetermined first rotational speed of the engine in a half-clutch state (e.g., the third rotational speed E3). The upper limit of the engine speed in the first region RE1 is lower than the fourth engine speed E4. The second region RE2 is from a predetermined first engine speed (e.g., the third engine speed E3) to a predetermined second engine speed (e.g., the sixth engine speed E6) higher than the first predetermined engine speed in the half-clutch state. The half-clutch state region RH is from the first engine speed E1 to the fifth engine speed E5.

[0091] Next, the relationship between the engine speed and the pressing of the input side rotating plate 20 and the output side rotating plate 22 will be described. As shown in Figures 33A and 33B, when the engine speed is from the first rotation speed E1 to the second rotation speed E2, the pressing member 150 presses the flange 68 of the second clutch center 51 in the second direction D2. This causes the second clutch center 51 to move in the second direction D2 relative to the first clutch center 41, and the input side rotating plate 20 and the output side rotating plate 22 come into contact with each other, resulting in a partial clutch state. When the partial clutch state is reached, the rotational driving force of the input shaft begins to be transmitted to the output shaft 15. When the engine speed reaches the second speed E2, the first weight member 130A attempts to move the pressing member 150 further in the second direction D2. Because the input side rotating plate 20 and the output side rotating plate 22 are in contact with each other, the pressing member 150 attempts to move the pressure member 70 in the second direction D2 via the input side rotating plate 20 and the output side rotating plate 22. Here, the wall surface 84D1 (see FIG. 20) on the first direction D1 side of the spring accommodating portion 84 of the pressure member 70 is in contact with the wall surface 41D2 (see FIG. 20) on the second direction D2 side of the first clutch center 41, and the pressure member 70 is urged in the first direction D1 by the clutch spring 25. For this reason, the pressing member 150 remains at the position PDS (see FIG. 33B ) at the second rotational speed E2 until the engine rotational speed further increases from the second rotational speed E2 and the force in the second direction D2 acting on the pressing member 150 from the weight members 130 (here, the first weight member 130A and the second weight member 130B) exceeds the spring force of the clutch spring 25. In other words, the spring force of the clutch spring 25 keeps the pressure member 70 in contact with the wall surface 41D2 of the first clutch center 41 on the second direction D2 side. Then, when the engine speed reaches the third speed E3 and the second weight member 130B begins to press the pressing member 150, both the first weight member 130A and the second weight member 130B press the pressing member 150, and the force acting in the second direction D2 from the weight member 130 to the pressing member 150 exceeds the spring force of the clutch spring 25.As a result, the pressing member 150 moves further in the second direction D2, moving the second clutch center 51 and the pressure member 70 in the second direction D2. As a result, the input side rotating plate 20 and the output side rotating plate 22 are further pressed together, and when the engine speed is fifth rotation speed E5, the input side rotating plate 20 and the output side rotating plate 22 are completely pressed together.

[0092] Fifth Embodiment Figure 34 is a plan view showing a portion of a centrifugal clutch mechanism 520 according to a fifth embodiment. The centrifugal clutch mechanism 520 includes a plurality of weight members 130, a holding member 140, a pressing member 150 (see Figure 1), a spring 160, and a contact member 170 (see Figure 1). The plurality of weight members 130 include a first weight member 130A and a second weight member 130B. The first weight member 130A and the second weight member 130B have the same configuration except for the number of springs 160 that bias the first weight member 130A toward the inner side M2 ​​in the radial direction M. The first weight member 130A is biased toward the inner side M2 ​​in the radial direction M by one spring 160. The second weight member 130B is biased toward the inner side M2 ​​in the radial direction M by two springs 160. The timing at which the first weight member 130A and the second weight member 130B start moving, their positions, etc. according to the fifth embodiment are the same as those of the first weight member 130A and the second weight member 130B according to the fourth embodiment.

[0093] Sixth Embodiment Figure 35 is a plan view showing a portion of a centrifugal clutch mechanism 620 according to a sixth embodiment. The centrifugal clutch mechanism 620 has a plurality of weight members 130, a holding member 140, a pressing member 150 (see Figure 1), a spring 160, a contact member 170 (see Figure 1), and a suppression member 190. The plurality of weight members 130 include a first weight member 130A and a second weight member 130B. The first weight member 130A and the second weight member 130B have the same configuration except that the second weight member 130B is provided with a second suppression member 190B, which will be described later. The timing at which the first weight member 130A and the second weight member 130B start moving and their positions according to the sixth embodiment are the same as those of the first weight member 130A and the second weight member 130B according to the fourth embodiment.

[0094] As shown in FIG. 35 , the suppression member 190 includes a first suppression member 190A provided on the holding member 140 and a second suppression member 190B provided on the second weight member 130B. The first suppression member 190A and the second suppression member 190B are, for example, magnets. When the second weight member 130B is at a position PI on the inner side M2 ​​in the radial direction M, the first suppression member 190A and the second suppression member 190B are attracted to each other by magnetic force. The suppression member 190 suppresses the start of movement of the second weight member 130B from the position PI on the inner side M2 ​​in the radial direction M to the position PO on the outer side M1 in the radial direction M until the centrifugal force reaches a predetermined magnitude (for example, until the second rotation speed E2 is reached). That is, when the adhesive force between the first suppression member 190A and the second suppression member 190B is greater than the centrifugal force, the second weight member 130B does not move in the radial direction M. The suppression member 190 prevents the second weight member 130B from pressing the pressing member 150 until the centrifugal force reaches a predetermined magnitude. When the centrifugal force exceeds the predetermined magnitude (for example, when the second rotation speed E2 is reached), the suppression member 190 allows the second weight member 130B to start moving from a position PI on the inner side M2 ​​in the radial direction M to a position PO on the outer side M1 in the radial direction M. That is, when the centrifugal force becomes greater than the adhesive force between the first suppression member 190A and the second suppression member 190B, the second weight member 130B moves in the radial direction M. The suppression member 190 allows the second weight member 130B to press the pressing member 150 when the centrifugal force exceeds a predetermined magnitude.

[0095] Seventh Embodiment Figure 36 is a plan view showing a portion of a centrifugal clutch mechanism 720 according to a seventh embodiment. The centrifugal clutch mechanism 720 has the same configuration as the centrifugal clutch mechanism 420, except that the number of first weight members 130A and the number of second weight members 130B are different. The number of first weight members 130A is greater than the number of second weight members 130B. The number of second weight members 130B may also be greater than the number of first weight members 130A. As with the centrifugal clutch mechanism 720, the numbers of first weight members 130A and second weight members 130B may also be different in the centrifugal clutch mechanisms 520 and 620. The timing at which the first weight member 130A and the second weight member 130B start moving, their positioning, etc., according to the seventh embodiment are the same as those of the first weight member 130A and the second weight member 130B according to the fourth embodiment.

[0096] Eighth Embodiment Figure 37 is a cross-sectional view showing a centrifugal clutch mechanism 820 and its periphery according to an eighth embodiment. The centrifugal clutch mechanism 820 has a plurality of weight members 830, a holding member 840, a pressing member 850, a spring 160, and a contact member 170. As shown in Figure 38, the plurality of weight members 830 include a first weight member 830A and a second weight member 830B.

[0097] 37 and 38 , the holding member 840 holds the weight member 830 movably between a position PI on the inner side M2 ​​in the radial direction M and a position PO on the outer side M1 in the radial direction M. The holding member 840 is formed in an annular shape. The holding member 840 is formed by aluminum die-casting. The holding member 840 includes a main body 141, a plurality of engaging claws 143, a plurality of accommodating recesses 145, and a pressing portion 149 (see FIG. 1 ).

[0098] As shown in FIG. 39 , the weight member 830 includes a weight body 830X, a through-hole 833, a cylindrical member 834, and a spherical member 835. The through-hole 833 is formed in the weight body 830X. The through-hole 833 is a hole that penetrates the weight body 830X in the axial direction of the output shaft 15 (i.e., direction D). A cylindrical member 834 that rotatably holds a spherical member 835 is provided in the through-hole 833. The cylindrical member 834 is fitted into the through-hole 833 and extends in the axial direction of the output shaft 15 (i.e., direction D). A portion of the spherical member 835 protrudes from the opening of the through-hole 833. The spherical member 835 is, for example, a steel ball. The spherical member 835 includes a first spherical member 835A that can come into contact with (abut against) the pressing member 850, and a second spherical member 835B that can come into contact with (abut against) the holding member 840. The first spherical member 835A is provided so as to be able to roll on an inclined surface 856 (described later) of the pressing member 850. The second spherical member 835B is provided so as to be able to roll on the accommodating recess 145 of the holding member 840. The first spherical member 835A is an example of a weight member-side abutment portion.

[0099] The pressing member 850 is configured to be able to move in the axial direction (here, the second direction D2) of the output shaft 15 by moving the weight member 830 from a position PI on the inner side M2 ​​in the radial direction M to a position PO on the outer side M1 in the radial direction M, thereby pressing the input side rotating plate 20 and the output side rotating plate 22 together. As shown in FIG. 40 , the pressing member 850 is formed in an annular shape. The pressing member 850 includes an annular main body 851, multiple protrusions 855, and multiple engaging claws 843. The engaging claws 843 protrude from an outer peripheral edge 851E of the main body 851 toward the outer side M1 in the radial direction M. The engaging claws 843 are formed integrally with the main body 851. The engaging claws 843 engage with the clutch housing 30 (see FIG. 1 ). The multiple engaging claws 843 are aligned in the circumferential direction S.

[0100] As shown in FIG. 40 , the protrusion 855 protrudes from the main body 851 in the axial direction of the output shaft 15 (here, the first direction D1). The protrusion 855 extends in the radial direction M. The multiple protrusions 855 are aligned in the circumferential direction S. The protrusion 855 has an inclined surface 856 that contacts the weight member 830. More specifically, the inclined surface 856 contacts (abuts) the first spherical member 835A of the weight member 830. The inclined surface 856 is inclined with respect to the axial direction of the output shaft 15 (i.e., direction D). The inclined surface 856 inclines toward the first direction D1 as it moves outward M1 in the radial direction M. A guide groove 857 that guides movement of the first spherical member 835A in the radial direction M is formed in the inclined surface 856. The guide groove 857 extends in the radial direction M. The inclined surface 856 is an example of a pressing member-side abutment portion. When the weight member 830 moves from a position PI on the inner side M2 ​​in the radial direction M to a position PO on the outer side M1 in the radial direction M, the first spherical member 835A and the inclined surface 856 abut against each other, and the pressing member 850 moves in the axial direction of the output shaft 15 (here, the second direction D2).

[0101] In the eighth embodiment, the first weight member 830A and the second weight member 830B are lighter than the second weight member 830B. The timing at which the first weight member 830A and the second weight member 830B start moving and their positions are similar to those of the first weight member 130A and the second weight member 130B according to the eighth embodiment. Similarly to the fifth embodiment, the first weight member 830A and the second weight member 830B may have different numbers of springs 160 biasing them toward the inner side M2 ​​in the radial direction M. Similarly to the sixth embodiment, the centrifugal clutch mechanism 820 may include a suppressing member 190. Similarly to the seventh embodiment, the number of first weight members 830A and the number of second weight members 830B may be different.

[0102] In the eighth embodiment described above, the first weight member 830A is lighter than the second weight member 830B, but this is not limiting. For example, when the first weight member 830A and the second weight member 830B have the same configuration, as shown in FIG. 41 , the position PIA of the inner side M2 ​​of the first weight member 830A in the radial direction M and the position PIB of the inner side M2 ​​of the second weight member 830B in the radial direction M may be different in relation to the radial direction M. In this case, the first spherical member 835A of the first weight member 830A presses the pressing member 850 in the second direction D2 via the inclined surface 856 between the positions PIA and PIB. At this time, the first spherical member 835A of the second weight member 830B does not press the pressing member 850 in the second direction D2. Between position PIB and position PO, the first spherical member 835A of the first weight member 830A presses the pressing member 850 in the second direction D2 via the inclined surface 856, and the first spherical member 835A of the second weight member 830B presses the pressing member 850 in the second direction D2 via the inclined surface 856. That is, the first weight member 830A presses the pressing member 850 within the range of region PRA, and the second weight member 830B presses the pressing member 850 within the range of region PRB. Note that in this modification, the shape of the first spherical member 835A of the first weight member 830A and the shape of the first spherical member 835A of the second weight member 830B may be different. In Figure 41, the first spherical member 835A at position PI on the inner side M2 ​​in the radial direction M is shown by a solid line, and the first spherical member 835A at position PO on the outer side M1 in the radial direction M is shown by a dashed dotted line.

[0103] In the eighth embodiment described above, the first weight member 830A is lighter than the second weight member 830B, and the inclined surface 856 on which the first spherical member 835A of the first weight member 830A rolls and the inclined surface 856 on which the first spherical member 835A of the second weight member 830B rolls have the same shape, but this is not limiting. For example, when the first weight member 830A and the second weight member 830B have the same configuration, the inclined surface 856A on which the first spherical member 835A of the first weight member 830A rolls and the inclined surface 856B on which the first spherical member 835A of the second weight member 830B rolls may have different shapes in a cross section including the axis of the output shaft 15, as shown in FIG. That is, the length of the inclined surface 856A in the radial direction M may be longer than the length of the inclined surface 856B in the radial direction M. An end 856BM2 on the inner side M2 ​​of the inclined surface 856B in the radial direction M is located on the outer side M1 in the radial direction M than an end 856AM2 on the inner side M2 ​​of the inclined surface 856A in the radial direction M. In this case, a position PIA on the inner side M2 ​​of the first weight member 830A in the radial direction M and a position PIB on the inner side M2 ​​of the second weight member 830B in the radial direction M are different in the radial direction M. Between positions PIA and PIB, the first spherical member 835A of the first weight member 830A presses the pressing member 850 in the second direction D2 via the inclined surface 856A. At this time, the first spherical member 835A of the second weight member 830B does not press the pressing member 850 in the second direction D2. Between position PIB and position PO, the first spherical member 835A of the first weight member 830A presses the pressing member 850 in the second direction D2 via the inclined surface 856A, and the first spherical member 835A of the second weight member 830B presses the pressing member 850 in the second direction D2 via the inclined surface 856B. That is, the first weight member 830A presses the pressing member 850 within the range of the region PRA, and the second weight member 830B presses the pressing member 850 within the range of the region PRB. In this modified example, the position of the inner side M2 ​​in the radial direction M of the second weight member 830B may be the same as the position PIA of the inner side M2 ​​in the radial direction M of the first weight member 830A, and the second weight member 830B may be configured to abut from the end 856BM2 of the inner side M2 ​​in the radial direction M of the inclined surface 856B (i.e., to press the inclined surface 856B).42 , the first spherical member 835A at a position PI on the inner side M2 ​​in the radial direction M is indicated by a solid line, and the first spherical member 835A at a position PO on the outer side M1 in the radial direction M is indicated by a dashed dotted line.

[0104] 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.

[0105] In the above-described embodiments, the spring 160 is given as an example of the biasing member, but the biasing member is not limited to this. The biasing member may be, for example, an elastic body such as rubber.

[0106] In the above-described embodiments, the pressure-side inclined surface 150F is an example of the pressure-side sliding portion, and the weight-side inclined surface 130F is an example of the weight-side sliding portion, both of which are inclined surfaces inclined with respect to the axial direction (i.e., direction D) of the output shaft 15. However, the present invention is not limited to this. It is sufficient that at least one of the pressure-side sliding portion and the weight-side sliding portion is an inclined surface inclined with respect to the axial direction of the output shaft 15, and the other may be a protrusion or the like instead of an inclined surface.

[0107] In the above-described embodiments, the weight members 130, 230 include the biasing member holding portion 131, but may not include the biasing member holding portion 131. In this case, for example, the spring 160 is disposed so as to abut against an end (e.g., an end face) of the weight member 130, 230 on the outer side M1 in the radial direction M.

[0108] In the first embodiment described above, the weight member 130 includes the first flat surface 133 and the second flat surface 135 that are provided so as to be slidable relative to the holding member 140. However, the weight member 130 may include only one of these flat surfaces. The first flat surface 133 and the second flat surface 135 are examples of flat surfaces. In this case, the weight member 130 itself can slide more effectively relative to the holding member 140 via the first flat surface 133 or the second flat surface 135.

[0109] In each of the above-described embodiments, the pressing member 150 is configured to indirectly press the input side rotating plate 20 and the output side rotating plate 22 together via the flange 68 of the second clutch center 51, but this is not limiting. The pressing member 150 may also be configured to press the input side rotating plate 20 and the output side rotating plate 22 together by directly pressing the input side rotating plate 20 or the output side rotating plate 22.

[0110] In each of the above-described embodiments, the pressure member 70 holds one output side rotary plate 22 , but it may hold a plurality of output side rotary plates 22 .

[0111] In the above-described embodiments, the pressure member 70 holds some of the output rotating plates 22, and the clutch center 40 (more specifically, the second clutch center 51) holds other parts of the output rotating plates 22. However, the present invention is not limited to this. For example, the pressure member 70 may hold all of the output rotating plates 22.

[0112] In each of the above-described embodiments, the clutch center 40 includes the first clutch center 41 and the second clutch center 51, but the first clutch center 41 and the second clutch center 51 may be formed integrally.

[0113] In each of the above-described embodiments, the weight member 130 is configured to directly press the pressing member 150, but it may also be configured to indirectly press the pressing member 150.

[0114] In each of the above-described embodiments, an engine is used as the drive source, but the drive source is not limited to an engine and may be, for example, an electric motor.

[0115] The shape of the weight members 130, 230, 830 is not limited to the shapes in the above-described embodiments, and may be, for example, spherical.

[0116] The technology disclosed herein can be applied to various types of clutch devices. In the above-described embodiments, a so-called internal disengagement type clutch device is described as an example in which the pressure member 70 is located on the opposite side of the clutch housing 30 across the clutch center 40 in the axial direction of the output shaft 15, but the present invention is not limited to this. For example, the technology disclosed herein can be similarly applied to a so-called external disengagement type clutch device in which the pressure member 70 is located between the clutch center 40 and the clutch housing 30 in the axial direction of the output shaft 15.

[0117] REFERENCE SIGNS LIST 10 Clutch device 15 Output shaft 20 Input side rotating plate 22 Output side rotating plate 30 Clutch housing 40 Clutch center 70 Pressure member 120 Centrifugal clutch mechanism 130 Weight member 140 Holding member 141 Main body 141A Wall portion 141B Protruding portion 141E Outer circumferential edge 141T Thick portion 143 Engaging claw 143A Head portion 143B Root portion 145 Accommodating recess 150 Pressing member 160 Spring (biasing member) 161 First spring 162 Second spring

Claims

1. A clutch device for transmitting or interrupting the rotational drive 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 that is rotationally driven together with the output shaft; a pressure member that is provided so as to be able to approach or move away from the clutch center and that holds at least some of the 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; and a centrifugal clutch mechanism that has a plurality of weight members that are configured to be movable from a radially inner position to an outer position by centrifugal force that accompanies the rotation of the clutch housing, and that when the weight members are at the radially outer positions, press the input side rotating plates and the output side rotating plates together, enabling the rotational drive force of the input shaft to be transmitted to the output shaft, and that releases the pressing force between the input side rotating plates and the output side rotating plates, allowing the rotational drive force of the input shaft to be transmitted to the output shaft, when the weight members are at the radially inner positions, thereby interrupting the transmission of the rotational drive force of the input shaft to the output shaft. the centrifugal clutch mechanism comprises: a retaining member that retains the weight member movably between the radially inner position and the radially outer position; a biasing member that is provided on the retaining member and biases the weight member radially inward; and a pressing member that moves in the axial direction of the output shaft as the weight member moves from the radially inner position to the radially outer position, thereby pressing the input side rotating plate and the output side rotating plate together; the retaining member comprises: a ring-shaped main body; engagement claws that protrude radially outward from the outer peripheral edge of the main body and engage with the clutch housing; and an accommodating recess that is formed in the main body so as to be recessed in the axial direction of the output shaft and accommodates the weight member radially movably; and the main body comprises: a thick portion that includes: a wall portion located between the engagement claws and the accommodating recess in the radial direction; and a protrusion that protrudes radially inward from the wall portion and defines a part of the accommodating recess.

2. A clutch device according to claim 1, wherein the circumferential length of said protrusion is equal to or greater than the circumferential length of said engaging pawl.

3. A clutch device as set forth in claim 2, wherein, with respect to the circumferential direction, the direction in which the clutch center rotates is defined as a first circumferential direction, and the opposite direction of the first circumferential direction is defined as a second circumferential direction, the first circumferential end of the protrusion is located on the first circumferential side of the first circumferential end of the engaging claw, and the second circumferential end of the protrusion is located on the second circumferential side of the second circumferential end of the engaging claw.

4. A clutch device as set forth in claim 2, wherein the engaging pawl has a head and a root located radially inward of the head, the circumferential length of the head is longer than the circumferential length of the root, and when, with respect to the circumferential direction, the direction in which the clutch center rotates is defined as a first circumferential direction and the direction opposite to the first circumferential direction is defined as a second circumferential direction, the first circumferential end of the protrusion is located on the first circumferential side of the first circumferential end of the root, and the second circumferential end of the protrusion is located on the second circumferential side of the second circumferential end of the root.

5. A clutch device as described in claim 1 or 2, wherein the radial length from the outer peripheral edge of the main body to the radially inner end of the protrusion is longer than the radial length from the outer peripheral edge of the main body to the radially outer end of the engaging pawl.

6. A clutch device according to claim 1, wherein the biasing member includes a first spring and a second spring arranged side by side in the circumferential direction and housed in the housing recess, the first spring and the second spring being configured to bias the weight member inward in the radial direction, and the protrusion being located between the first spring and the second spring in the circumferential direction.

7. A clutch device as described in claim 1, wherein the weight members include: a first weight member that starts moving from the radially inner position toward the radially outer position when the rotation speed of the drive source is a first rotation speed; and a second weight member that starts moving from the radially inner position toward the radially outer position when the rotation speed of the drive source is a second rotation speed higher than the first rotation speed.

8. A clutch device according to claim 7, wherein said second weight member starts to move from said radially inner position toward said radially outer position in a half-clutch state.

9. A clutch device according to claim 7, wherein one of said first weight members is located between two of said second weight members that are aligned in the circumferential direction.

10. A clutch device as described in claim 7, wherein the weight members include a plurality of the first weight members and a plurality of the second weight members, and when viewed in the axial direction of the output shaft, some of the first weight members are arranged line-symmetrically with respect to a line passing through the center of the output shaft, and some of the second weight members are arranged line-symmetrically with respect to the line.

11. The clutch device according to claim 7, wherein the weight members include a plurality of the first weight members and a plurality of the second weight members, and the number of the first weight members is different from the number of the second weight members.

12. The clutch device of claim 11, wherein the number of said second weight members is greater than the number of said first weight members.

13. The clutch device according to claim 7, wherein the weight members include a plurality of the first weight members and a plurality of the second weight members, and the number of the first weight members is the same as the number of the second weight members.

14. A clutch device as described in claim 7, wherein the first weight member is configured to reach the radially outer position when the rotational speed of the drive source is a third rotational speed that is higher than the second rotational speed, and the first radial movement amount of the first weight member from the first rotational speed to the second rotational speed is different from the second radial movement amount of the first weight member from the second rotational speed to the third rotational speed.

15. The clutch device of claim 14, wherein the second amount of movement is greater than the first amount of movement.

16. A clutch device according to claim 7, wherein the radially inner position of the first weight member and the radially inner position of the second weight member are different in the radial direction.

17. A clutch device as described in claim 7, wherein the clutch center comprises a center-side cam portion having a center-side assist cam surface that generates a force in a direction from the pressure member toward the clutch center in order to increase the pressure contact force between the input side rotating plate and the output side rotating plate when the clutch center rotates relative to the pressure member; the pressure member comprises a pressure-side cam portion that is arranged to be able to come into contact with the center-side assist cam surface and has a pressure-side assist cam surface that generates the force when the pressure member rotates relative to the clutch center; and the center-side assist cam surface and the pressure-side assist cam surface are configured to begin generating a force in a direction from the pressure member toward the clutch center when the rotational speed of the drive source is a third rotational speed that is higher than the first rotational speed.

18. The clutch device according to claim 17, wherein the third rotational speed is higher than the second rotational speed.

19. The clutch device according to claim 17, wherein the third rotational speed is lower than the second rotational speed.

20. A clutch device as described in claim 1, wherein the weight member includes a first weight member and a second weight member, and the centrifugal clutch mechanism is provided with a suppression member that suppresses the start of movement of the second weight member from the radially inner position to the radially outer position until the centrifugal force reaches a predetermined magnitude.

21. The clutch device according to claim 20, wherein the suppression member allows the second weight member to start moving from the radially inner position to the radially outer position when the centrifugal force becomes greater than the predetermined magnitude.

22. A clutch device according to claim 20, wherein one of the first weight members is located between two of the second weight members that are aligned in the circumferential direction.

23. A clutch device as described in claim 20, wherein the weight members include a plurality of the first weight members and a plurality of the second weight members, and when viewed in the axial direction of the output shaft, some of the first weight members are arranged line-symmetrically with respect to a line passing through the center of the output shaft, and some of the second weight members are arranged line-symmetrically with respect to the line.

24. The clutch device of claim 20, wherein the weight members include a plurality of the first weight members and a plurality of the second weight members, and the number of the first weight members is different from the number of the second weight members.

25. The clutch device of claim 24, wherein the number of said first weight members is greater than the number of said second weight members.

26. The clutch device according to claim 20, wherein the weight members include a plurality of the first weight members and a plurality of the second weight members, and the number of the first weight members is the same as the number of the second weight members.

27. A clutch device as described in claim 1, wherein the weight member includes: a first weight member that begins to press against the pressure contact member when the rotational speed of the drive source is a first rotational speed, thereby moving the pressure contact member in the axial direction; and a second weight member that begins to press against the pressure contact member when the rotational speed of the drive source is a second rotational speed higher than the first rotational speed, thereby moving the pressure contact member in the axial direction.

28. A clutch device as set forth in claim 27, wherein the weight member comprises a weight member-side abutment portion capable of abutting against the pressing member, the pressing member comprises a pressing member-side abutment portion capable of abutting against the weight member-side abutment portion, the weight member is configured to abut against the pressure member-side abutment portion when the weight member moves from the radially inner position to the radially outer position, and the pressing member moves in the axial direction of the output shaft, and in a cross-sectional view including the axis of the output shaft, at least one of the shape and position of the weight member-side abutment portion of the first weight member differs from at least one of the shape and position of the weight member-side abutment portion of the second weight member.

29. A clutch device as set forth in claim 27, wherein the weight member comprises a weight member-side abutment portion capable of abutting against the pressing member, the pressing member comprises a pressing member-side abutment portion capable of abutting against the weight member-side abutment portion, the weight member is configured to abut against the pressing member-side abutment portion when the weight member moves from the radially inner position to the radially outer position, and the pressing member moves in the axial direction of the output shaft, and in a cross-sectional view including the axis of the output shaft, at least one of the shape and position of the pressing member-side abutment portion abutting against the weight member-side abutment portion of the first weight member differs from at least one of the shape and position of the pressing member-side abutment portion abutting against the weight member-side abutment portion of the second weight member.

30. A clutch device as described in claim 28 or 29, wherein the radially inner diameter end of the pressure-contact member side abutment portion that abuts against the weight-contact member side abutment portion of the second weight member is located radially outward of the radially inner diameter end of the pressure-contact member side abutment portion that abuts against the weight-contact member side abutment portion of the first weight member.

31. A clutch device as set forth in claim 1, wherein the weight member includes a first weight member and a second weight member, and the centrifugal clutch mechanism is provided with a suppression member that suppresses the second weight member from pressing the pressure contact member until the centrifugal force reaches a predetermined magnitude.

32. A clutch device as set forth in claim 1, wherein some of the weight members press the pressure contact member when the rotation speed of the drive source is in a first range, and all of the weight members press the pressure contact member when the rotation speed of the drive source is in a second range.

33. A clutch device as described in claim 32, wherein the first region is from the rotational speed of the driving source at the time of vehicle start to a predetermined first rotational speed of the driving source in a half-clutch state, and the second region is from the predetermined first rotational speed to a predetermined second rotational speed higher than the predetermined first rotational speed.

34. A clutch device as described in claim 32, wherein the clutch center comprises a center-side cam portion having a center-side assist cam surface that generates a force in a direction from the pressure member toward the clutch center in order to increase the pressure contact force between the input-side rotating plate and the output-side rotating plate when the clutch center rotates relative to the pressure member, and the pressure member comprises a pressure-side cam portion that is arranged to be able to come into contact with the center-side assist cam surface and has a pressure-side assist cam surface that generates the force when the pressure member rotates relative to the clutch center, and wherein the upper limit rotational speed of the first region is lower than the rotational speed at which the force begins to be generated by the action of the center-side assist cam surface and the pressure-side assist cam surface.

35. A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a clutch center accommodated in a clutch housing that holds a plurality of input side rotating plates that are rotationally driven by the rotational drive of the input shaft and that rotates together with the output shaft; a pressure member that is provided so as to be able to approach or move away from the clutch center, that holds at least some of 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 centrifugal clutch mechanism having a plurality of weight members configured to be movable from a radially inner position to an outer position by centrifugal force accompanying rotation of the clutch housing, and which presses the input side rotating plate and the output side rotating plate together when the weight members are at the radially outer position, thereby enabling transmission of the rotational drive force of the input shaft to the output shaft, and which releases the pressing force between the input side rotating plate and the output side rotating plate when the weight members are at the radially inner position, thereby blocking transmission of the rotational drive force of the input shaft to the output shaft; the centrifugal clutch mechanism comprising: a holding member which holds the weight members movably between the radially inner position and the radially outer position; a biasing member which is provided on the holding member and which biases the weight members radially inward; and a pressing member which moves in the axial direction of the output shaft as the weight members move from the radially inner position to the radially outer position, thereby pressing the input side rotating plate and the output side rotating plate together, a clutch device in which the retaining member comprises: a ring-shaped main body; an engagement claw that protrudes radially outward from the outer peripheral edge of the main body and engages with the clutch housing; and an accommodating recess that is formed in the main body so as to be recessed in the axial direction of the output shaft and that accommodates the weight member so as to be movable in the radial direction; the main body comprises a wall portion that is located between the engagement claw and the accommodating recess in the radial direction; and the radial length of the wall portion is longer than the radial length from the outer peripheral edge of the main body to the radially outer end of the engagement claw.

36. A clutch device according to claim 35, wherein the circumferential length of said wall portion is equal to or greater than the circumferential length of said engaging pawl.

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