Clutch device

Abstract

A clutch center 440 includes a plurality of clutch center teeth 47 holding an output-side rotary plate 22 and arranged in a circumferential direction S, and a plurality of spline grooves 48 formed between the adjacent clutch center teeth 47. The plurality of spline grooves 48 include first spline grooves 48A of each of which the length in the circumferential direction S is a first length LS1 and second spline grooves 48B of each of which the length in the circumferential direction S is a second length LS2. When the clutch center 440 is equally divided into a first region CT1 and a second region CT2 by a straight line LC passing through a center 440C of the clutch center 440 when viewed in an axial direction D of an output shaft 15, the plurality of clutch center teeth 47 and the plurality of spline grooves 48 are not line-symmetrical with respect to the straight line LC in the first region CT1 and the second region CT2.

Description

Clutch device

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

[0002] A saddle-type vehicle such as a motorcycle includes a clutch device that can transmit and cut off 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 including a clutch center that holds an output-side rotating plate and a pressure plate provided so as to be able to approach and separate from the clutch center. In such a clutch device, the rotational driving force is transmitted or cut off by pressing or separating the input-side rotating plate and the output-side rotating plate.

[0003] Japanese Unexamined Patent Application Publication No. 2024-133236

[0004] In the clutch device as described above, when the weights of the clutch center and the pressure plate become relatively heavy, the weight of the entire clutch device increases. Since the clutch device is mounted on a vehicle such as a motorcycle, for example, a relatively lightweight one is preferable.

[0005] The present invention has been made in view of this point, and its object is to provide a clutch device in which weight reduction is achieved.

[0006] The clutch device according to the present invention is a clutch device that transmits or interrupts the rotational driving force of an input shaft, which is rotationally driven by the driving force of a drive source, to an output shaft, and comprises a clutch center housed in a clutch housing that holds a plurality of input-side rotating plates that are rotationally driven by the rotational drive of the input shaft, and which rotates together with the output shaft, and a pressure plate provided so as to be able to approach and separate from the clutch center, and which can press the input-side rotating plates and a plurality of output-side rotating plates arranged alternately with the input-side rotating plates, wherein the clutch center comprises an output shaft holding portion to which the output shaft is connected, an outer cylindrical portion located radially outside the output shaft holding portion, and a portion that holds the output-side rotating plates, The clutch center comprises a plurality of clutch center teeth that protrude radially outward from the outer cylinder and are arranged in the circumferential direction, and a plurality of spline grooves formed between adjacent clutch center teeth, wherein the plurality of spline grooves include a first spline groove having a first length in the circumferential direction and a second spline groove having a second length in the circumferential direction that is longer than the first length, and when the clutch center is divided into a first region and a second region by a straight line passing through the center of the clutch center when viewed in the axial direction of the output shaft, the plurality of clutch center teeth and the plurality of spline grooves are not symmetrical with respect to the straight line in the first region and the second region.

[0007] According to the clutch device of the present invention, the plurality of spline grooves include a first spline groove having a first length in the circumferential direction and a second spline groove having a second length in the circumferential direction that is longer than the first length. When the clutch center is divided into a first region and a second region by a straight line passing through the center of the clutch center when viewed in the axial direction of the output shaft, the plurality of clutch center teeth and the plurality of spline grooves are not symmetrical with respect to the straight line in the first region and the second region. That is, the clutch center teeth are not arranged at equal intervals in the circumferential direction, and the number of clutch center teeth is less than when they are arranged at equal intervals. As a result, the clutch center can be made lighter, and the weight of the clutch device can be reduced.

[0008] Another clutch device according to the present invention is a clutch device that transmits or interrupts the rotational driving force of an input shaft, which is rotationally driven by the driving force of a drive source, to an output shaft, and comprises a clutch center housed in a clutch housing that holds a plurality of input-side rotating plates that are rotationally driven by the rotational drive of the input shaft, and which rotates together with the output shaft, and a pressure plate provided so as to be able to approach and move away from the clutch center, and which can press the input-side rotating plates and a plurality of output-side rotating plates arranged alternately with the input-side rotating plates, wherein the output-side rotating plates have an annular rotating plate body and a plurality of rotating plate teeth that protrude radially inward from the rotating plate body and are arranged in the circumferential direction, the plurality of rotating plate teeth of the output-side rotating plates are provided at predetermined intervals in the circumferential direction, and the pressure plate has a pressure plate body and a pressure plate body that protrudes radially outward from the pressure plate body The pressure plate has a flange located on the side and extending radially outward, a plurality of pressure plate teeth extending axially along the output shaft and arranged circumferentially, and a plurality of intertooth portions formed between adjacent pressure plate teeth, wherein the plurality of intertooth portions include a first intertooth portion whose circumferential length is a first intertooth length and a second intertooth portion whose circumferential length is a second intertooth length longer than the first intertooth length, and when the pressure plate is divided into a first pressure plate region and a second pressure plate region by a pressure plate line passing through the center of the pressure plate when viewed in the axial direction of the output shaft, the plurality of pressure plate teeth and the plurality of intertooth portions are not symmetrical with respect to the pressure plate line in the first pressure plate region and the second pressure plate region.

[0009] According to the clutch device of the present invention, each of the multiple intertotal portions includes a first intertotal portion whose circumferential length is a first intertotal length and a second intertotal portion whose circumferential length is a second intertotal length longer than the first intertotal length. When the pressure plate is divided into a first pressure plate region and a second pressure plate region by a pressure plate line passing through the center of the pressure plate when viewed in the axial direction of the output shaft, the multiple pressure plate teeth and multiple intertotal portions in the first and second pressure plate regions are not symmetrical with respect to the pressure plate line. That is, the pressure plate teeth are not arranged at equal intervals in the circumferential direction, and the number of pressure plate teeth is less than when they are arranged at equal intervals. As a result, the pressure plate can be made lighter, and the clutch device can be made lighter.

[0010] According to the present invention, a lightweight clutch device can be provided.

[0011] Figure 1 is a cross-sectional view of the clutch device according to the first embodiment. Figure 2 is a perspective view of the clutch center according to the first embodiment. Figure 3 is a view of the clutch center and output side rotating plate from the left. Figure 4 is a view of the clutch center according to the first embodiment from the left. Figure 5 is a view of the clutch center according to the first embodiment from the right. Figure 6 is a perspective view of the clutch center according to the first embodiment. Figure 7 is a side view showing the output side rotating plate held by the clutch center teeth of the clutch center according to the first embodiment. Figure 8 is a perspective view of the pressure plate according to the first embodiment. Figure 9A is a view of the pressure plate according to the first embodiment from the right. Figure 9B is a view of the pressure plate according to the first embodiment from the right. Figure 10 is a view of the pressure plate and output side rotating plate from the right. Figure 11 is a side view showing the pressure plate and clutch center assembled. Figure 12 is a cross-sectional view of the section A-A in Figure 11. Figure 13A is a schematic diagram illustrating the operation of the clutch center teeth and pressure plate teeth. Figure 13B is a schematic diagram illustrating the operation of the clutch center teeth and pressure plate teeth when the clutch center rotates in the opposite direction in the circumferential direction to when shown in Figure 13A. Figure 14 is a view of the clutch center according to the second embodiment from the left. Figure 15 is a view of the pressure plate according to the second embodiment from the right. Figure 16 is a view of the pressure plate and output side rotating plate from the right. Figure 17 is a cross-sectional view showing the assembled state of the pressure plate and clutch center. Figure 18 is a cross-sectional view showing the assembled state of the pressure plate and clutch center according to a modified example. Figure 19 is a cross-sectional view showing the assembled state of the pressure plate and clutch center according to the third embodiment. Figure 20 is a cross-sectional view of the clutch device according to the fourth embodiment. Figure 21 is a perspective view of the clutch center according to the fourth embodiment. Figure 22 is a plan view of the clutch center according to the fourth embodiment. Figure 23 is a plan view showing the output side rotating plate held by the clutch center teeth of the clutch center according to the fourth embodiment. Figure 24 is a perspective view of the pressure plate according to the fourth embodiment.Figure 25 is a plan view of a pressure plate according to the fourth embodiment. Figure 26 is a plan view of a modified pressure plate.

[0012] Hereinafter, embodiments of the clutch device according to the present invention will be described with reference to the drawings. Naturally, the embodiments described herein are not intended to particularly limit the present invention. Furthermore, the same reference numerals are used for members and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate.

[0013] <First Embodiment> Figure 1 is a cross-sectional view of a clutch device 10 according to the first embodiment. The clutch device 10 is installed in a vehicle such as a motorcycle. The clutch device 10 is a device that transmits the rotational driving force of the input shaft (e.g., crankshaft) of a power source to the output shaft 15, or interrupts the rotational driving force from the input shaft to the output shaft 15. The power source is, for example, the engine of a motorcycle or an electric motor.

[0014] In the drawings, the symbols L and R represent left and right, respectively. The clutch device 10 comprises an output shaft 15, a clutch housing 30, a clutch center 40, and a pressure plate 70. In the following description, the direction of the axis CL1 of the output shaft 15 is referred to as the axial direction D, one side of the axial direction D is referred to as the first axial direction, and the other side of the axial direction D is referred to as the second axial direction. In this embodiment, the output shaft 15 extends in the left-right direction, and the axial direction D coincides with the left-right direction. The first axial direction corresponds to the rightward R, and the second axial direction corresponds to the leftward L. The first axial direction is the direction in which the pressure plate 70 approaches the clutch center 40, and the second axial direction is the direction in which the pressure plate 70 moves away from the clutch center 40. The output shaft 15, clutch housing 30, clutch center 40, and pressure plate 70 rotate around the axis CL1 of the output shaft 15. In the following, the direction of the circumference centered on the axis CL1 is referred to as the circumferential direction S (see Figure 2). Of the circumferential directions S, the counterclockwise direction when viewed from the right R is referred to as the first circumferential direction S1 (see Figure 2), and the clockwise direction when viewed from the right R is referred to as the second circumferential direction S2 (see Figure 2). When the clutch device 10 is engaged, the clutch housing 30, clutch center 40, and pressure plate 70 rotate in the first circumferential direction S1. The axis CL1 of the output shaft 15 is the center of the output shaft 15 when viewed in the axial direction D. In the following description, unless otherwise specified, "radial direction" refers to the radial direction Q of the output shaft 15. However, the above directions are merely defined for the convenience of explanation and do not limit the installation configuration of the clutch device 10 or the present invention in any way. For example, the axial direction D may be the vertical direction, etc.

[0015] As shown in Figure 1, the clutch device 10 includes an output shaft 15, a clutch housing 30, a clutch center 40, and a pressure plate 70, as well as a plurality of input-side rotating plates 20, a plurality of output-side rotating plates 22, a pressure spring 25, and a support plate 100. The rotational axes of the clutch housing 30 and the pressure plate 70 are coaxial (on the axis CL1 of the output shaft 15).

[0016] As shown in Figure 1, the output shaft 15 is a hollow shaft. The right end of the output shaft 15 rotatably supports the input gear 35 and clutch housing 30, which will be described later, via a needle bearing 15A. The output shaft 15 fixedly supports the clutch center 40 via a washer 15D and a nut 15N. That is, the output shaft 15 rotates integrally with the clutch center 40. The left end of the output shaft 15 is connected to, for example, the transmission (not shown) of a motorcycle.

[0017] The clutch housing 30 is formed in a bottomed cylindrical shape. The clutch housing 30 has a bottom wall 31 formed in a substantially disc shape and a side wall 33 extending to the right R from the edge of the bottom wall 31. The clutch housing 30 holds the input side rotating plate 20.

[0018] An input gear 35 is provided on the bottom wall 31 of the clutch housing 30. The input gear 35 is fixed to the bottom wall 31 by rivets 35B via a torque damper 35A (see Figure 20). The input gear 35 meshes with a drive gear (not shown) that rotates due to the rotational drive of the engine's input shaft. The input gear 35 is rotatable relative to the output shaft 15 and rotates together with the clutch housing 30.

[0019] The input-side rotating plate 20 is a flat plate formed in an annular shape. The input-side rotating plate 20 is held by the side wall 33 of the clutch housing 30. A notch 30C is formed in the side wall 33 of the clutch housing 30. The input-side rotating plate 20 engages with the notch 30C. The input-side rotating plate 20 is held by the clutch housing 30 by spline fitting. The input-side rotating plate 20 is provided so as to be immobile in the circumferential direction and displaceable in the axial direction D relative to the clutch housing 30. The input-side rotating plate 20 rotates together with the clutch housing 30.

[0020] The output-side rotating plate 22 is a flat plate formed in an annular shape. The output-side rotating plate 22 is held by the clutch center 40. As will be described later, the clutch center 40 has clutch center teeth 47. The output-side rotating plate 22 is engaged with the clutch center teeth 47. The output-side rotating plate 22 is provided so as to be immobile in the circumferential direction and displaceable in the axial direction D relative to the clutch center 40. The output-side rotating plate 22 rotates together with the clutch center 40.

[0021] Figure 3 shows the clutch center 40 and the output side rotating plate 22. As shown in Figure 3, the output side rotating plate 22 has an annular rotating plate body 22a, a plurality (34 in this embodiment) of rotating plate teeth 22b, and a plurality (34 in this embodiment) of rotating plate grooves 22c. The rotating plate teeth 22b extend inward from the rotating plate body 22a in the radial direction Q. The rotating plate teeth 22b are arranged in the circumferential direction S. The rotating plate grooves 22c are grooves formed between adjacent rotating plate teeth 22b. The reference numeral L20 indicates the spacing between adjacent rotating plate teeth 22b in the circumferential direction S.

[0022] As shown in Figure 1, the input-side rotating plates 20 and the output-side rotating plates 22 are arranged alternately in the axial direction D. In this embodiment, four input-side rotating plates 20 and three output-side rotating plates 22 are arranged.

[0023] As shown in Figure 1, the clutch center 40 is housed in the clutch housing 30. The clutch center 40 is positioned concentrically with the clutch housing 30. As shown in Figure 2, the clutch center 40 includes an output shaft holding portion 50 held on the output shaft 15 (see Figure 1), an outer cylindrical portion 45 located radially Q outward from the output shaft holding portion 50, a disc portion 44 connected to the output shaft holding portion 50 and the outer cylindrical portion 45, and an annular flange 68 located radially Q outward from the outer cylindrical portion 45.

[0024] As shown in Figures 2 and 4, the flange 68 extends radially outward from the right end of the outer cylinder portion 45 in the direction Q. As shown in Figure 1, when the clutch device 10 is connected, the flange 68, together with the flange 98 of the pressure plate 70 (described later), clamps the input-side rotating plate 20 and the output-side rotating plate 22. The flange 68 contacts and presses the input-side rotating plate 20R located furthest to the right R among the multiple input-side rotating plates 20. The flange 68 is provided so as to be able to press the input-side rotating plate 20 and the output-side rotating plate 22. The flange 68 is a member that applies pressing force to the input-side rotating plate 20 and the output-side rotating plate 22.

[0025] As shown in Figure 2, the output shaft holder 50 is formed in a cylindrical shape. The output shaft holder 50 extends in the axial direction D. The left end 50L of the output shaft holder 50 is located to the left L of the disc portion 44. An insertion hole 51 is formed through the output shaft holder 50 into which the output shaft 15 (see Figure 1) is inserted and spline fitted. Multiple spline grooves are formed along the axial direction on the inner circumferential surface 50A of the output shaft holder 50 that forms the insertion hole 51. The output shaft holder 50 is connected to the output shaft 15.

[0026] As shown in Figure 4, the disc portion 44 has a plurality (3 in this embodiment) of first through holes 44a and a plurality (3 in this embodiment) of second through holes 44b. The first through holes 44a and the second through holes 44b penetrate the disc portion 44 in the axial direction D (see Figure 1). The first through holes 44a and the second through holes 44b are arranged at equal intervals with respect to the circumferential direction S. The first through holes 44a and the second through holes 44b are arranged alternately in the circumferential direction S. The shapes of the first through holes 44a and the second through holes 44b are perfect circles when viewed from the axial direction D. The diameter R2 of the first through hole 44a and the diameter R3 of the second through hole 44b are the same length. The distance between the axis CL1 and the center 44C1 of the first through hole 44a is R4. As will be described later, the pressure plate 70 (see Figure 8) has a boss portion 84 (see Figures 8 and 9A). The position of the center 44C1 of the first through hole 44a in the radial direction Q is approximately the same as the position of the center 84E of the boss portion 84 (see Figure 12) in the radial direction Q. The diameter of the first through hole 44a is slightly larger than the diameter of the boss portion 84. The second through hole 44b is located radially outward from the first through hole 44a. A portion of the virtual circle CR1, centered on axis CL1 and passing through the center 44C1 of the first through hole 44a, overlaps with the second through hole 44b. Axis CL1 is located at the center of the output shaft 15 (see Figure 1) when viewed from the right R. A portion of the virtual circle CR2, centered on axis CL1 and passing through the center 44C2 of the second through hole 44b, overlaps with the first through hole 44a. The virtual circle CR2 is located radially outward Q than the virtual circle CR1. The innermost radial end 44bN of the second through hole 44b is located radially outward Q than the innermost radial end 44aN of the first through hole 44a. The virtual circle CR3, centered on axis CL1 and passing through end 44bN of the second through hole 44b, is located radially inward Q than the virtual circle CR1. Note that the number and arrangement of the first through holes 44a and the second through holes 44b are not limited to these. For example, the innermost radial end 44bN of the second through hole 44b may be located radially inward Q than the innermost radial end 44aN of the first through hole 44a.

[0027] As shown in Figure 2, the outer cylinder portion 45 is provided with a spline fitting portion 46. The spline fitting portion 46 has a plurality of clutch center teeth 47 extending in the axial direction D, and a plurality of spline grooves 48 formed between adjacent clutch center teeth 47.

[0028] As shown in Figure 4, the multiple (15 in this embodiment) clutch center teeth 47 are arranged in the circumferential direction S. The multiple clutch center teeth 47 are formed to have the same shape. The clutch center teeth 47 protrude outward from the outer cylinder portion 45 in the radial direction Q. As shown in Figure 1, the clutch center teeth 47 hold the output side rotating plate 22. Reference numeral L1 represents the length of the clutch center tooth 47 in the axial direction D. The length L1 is longer than the length L11 of the pressure plate teeth 77 in the axial direction D, which will be described later. As shown in Figure 3, the multiple clutch center teeth 47 are formed at non-uniform positions with respect to the circumferential direction S. The number of clutch center teeth 47 (15 in this embodiment) is less than the number of rotating plate teeth 22b of the output side rotating plate 22 (34 in this embodiment).

[0029] As shown in Figure 4, the multiple (15 in this embodiment) spline grooves 48 are arranged in the circumferential direction S. The spline groove 48 includes multiple spline grooves 48A, 48B, and 48C with different lengths in the circumferential direction S. The spline groove 48 has multiple (10 in this embodiment) first spline grooves 48A, second spline grooves 48B, and multiple (4 in this embodiment) third spline grooves 48C. In this embodiment, the number of second spline grooves 48B is 1. The reference numerals L2, L3, and L4 represent the lengths in the circumferential direction S of the first spline groove 48A, second spline groove 48B, and third spline groove 48C, respectively. The length L3 of the second spline groove 48B is longer than the length L2 of the first spline groove 48A. The length L4 of the third spline groove 48C is longer than the length L3 of the second spline groove 48B. Lengths L3 and L4 are longer than length L20 (see Figure 3), which is the distance between adjacent rotating plate teeth 22b. The second spline groove 48B is a groove that appears to have three missing clutch center teeth 47 compared to the case where the spline groove 48 has only the first spline groove 48A. Similarly, the third spline groove 48C is a groove that appears to have four missing clutch center teeth 47. The second spline groove 48B and the third spline groove 48C are examples of missing tooth grooves in the present invention. The clutch center 40 appears to have a total of 19 missing clutch center teeth 47. Length L20, which is the distance between adjacent rotating plate teeth 22b, is the same as the length S in the circumferential direction of the outer surface (tooth tip surface) in the radial direction Q of the clutch center teeth 47. In this embodiment, with respect to the circumferential direction S, the first spline groove 48A is positioned between the second spline groove 48B and the third spline groove 48C, or between two third spline grooves 48C aligned in the circumferential direction S. With respect to the circumferential direction S, the first spline groove 48A and the third spline groove 48C are positioned adjacent to each other. However, the number and arrangement of the first spline groove 48A, the second spline groove 48B, and the third spline groove 48C are not limited to this.

[0030] As shown in Figure 4, when viewed in the axial direction D of the output shaft 15, there exists a straight line LC that passes through the center 40C of the clutch center 40, bisects the clutch center 40 into a first region CT1 and a second region CT2, and in the first region CT1 and the second region CT2, the multiple clutch center teeth 47 and the multiple spline grooves 48 are not symmetrical with respect to the straight line LC. When the clutch center 40 is bisected into a first region CT1 and a second region CT2 by the straight line LC passing through the center 40C of the clutch center 40 when viewed in the axial direction D of the output shaft 15, the multiple clutch center teeth 47 and the multiple spline grooves 48 in the first region CT1 and the second region CT2 are not symmetrical with respect to the straight line LC. For example, in the example shown in Figure 4, the straight line LC passes through the first spline groove 48A and the second spline groove 48B, the number of clutch center teeth 47 in the first region CT1 is 7, and the number of clutch center teeth 47 in the second region CT2 is 8.

[0031] As shown in Figure 3, the output-side rotating plate 22 is held by the spline fitting portion 46 (see Figure 4) of the clutch center 40. The output-side rotating plate 22 is spline-fitted to the clutch center teeth 47 and spline groove 48 of the clutch center 40.

[0032] As shown in Figure 5, the clutch center 40 is equipped with a plurality (3 in this embodiment) of spring holders 54. The spring holders 54 extend inward from the outer cylinder portion 45 in the radial direction Q. The spring holders 54 are located outside the first through hole 44a in the radial direction Q. The plurality of spring holders 54 are arranged at equal intervals in the circumferential direction S. The pressure spring 25 is positioned inside the spring holders 54 in the radial direction Q (see also Figure 1). In Figure 5, the pressure spring 25 is shown by a dashed line. The spring holders 54 are members that suppress displacement of the pressure spring 25 in the radial direction Q and the circumferential direction S.

[0033] In this embodiment, the spring holder 54 has a support surface 54A facing the pressure spring 25 in the radial direction Q, a first support side surface 54B connected to the end of the support surface 54A on the first circumferential direction S1 side, and a second support side surface 54C connected to the end of the support surface 54A on the second circumferential direction S2 side. The first support side surface 54B and the second support side surface 54C are connected to the inner periphery of the outer cylinder portion 45. In this embodiment, the support surface 54A is a curved surface that is recessed outward in the radial direction Q, following the outer shape of the pressure spring 25. The support surface 54A has a shape that becomes more outward in the radial direction Q as it approaches the middle of the circumferential direction S. The support surface 54A and the outer shape of the pressure spring 25 are arranged concentrically around the axis CL2 of the pressure spring 25 (see also Figure 1). The outer shape of the pressure spring 25 refers to the shape (contour) of the pressure spring 25 on the outer side in the radial direction Q. The axis CL2 is located at the center of the pressure spring 25 when viewed from the right (R). When viewed along the axis CL1 of the output shaft 15, the axis CL1 and axis CL2 are parallel (see Figure 1). The symbol L5 represents the radial length Q of the spring holder 54. The radial length Q of the spring holder 54 varies depending on the position S in the circumferential direction of the spring holder 54. Here, the longest radial length Q of the spring holder 54 is defined as length L5. Length L5 is less than or equal to the radius R1 of the outer shape of the pressure spring 25. As shown in Figure 6, the right end of the spring holder 54 (the end on the right (R) side) is located to the left (L) of the right end of the outer cylinder portion 45. The left end of the spring holder 54 (the end on the left (L) side) is connected to the disc portion 44.

[0034] The outer cylinder portion 45 is provided with a plurality (3 in this embodiment) of oil discharge holes 45F that penetrate in the radial direction Q. The oil discharge holes 45F are formed in the spline grooves 48. In this embodiment, three oil discharge holes 45F are provided (see also Figure 5). The three oil discharge holes 45F will also be referred to as oil discharge holes 45F1, 45F2, and 45F3, respectively. However, when providing a description common to all of the oil discharge holes 45F1, 45F2, and 45F3, the name oil discharge hole 45F will be used as appropriate. The oil discharge holes 45F are positioned such that the distance in the circumferential direction S between the spring holder 54 located on the second circumferential direction S2 side and the oil discharge hole 45F is less than or equal to the length L5 in the radial direction Q of the spring holder 54 (see Figure 5). As shown in Figure 5, the oil discharge holes 45F are close to the spring holder 54 on the first circumferential direction S1 side. Specifically, the oil discharge hole 45F is located close to the first support side surface 54B of the spring holder 54 on the first circumferential direction S1 side. The oil discharge hole 45F may overlap with the spring holder 54 in the circumferential direction S at least partially. The distance L6 in the circumferential direction S between the first support side surface 54B of the spring holder 54, which is located on the second circumferential direction S2 side of the oil discharge hole 45F2, and the oil discharge hole 45F2 is shorter than the distance in the circumferential direction S between the second support side surface 54C of the spring holder 54, which is located on the first circumferential direction S1 side of the oil discharge hole 45F2, and the oil discharge hole 45F2. The length L6 is less than or equal to the radial length Q of the spring holder 54 L5. The phrase "the distance L6 in the circumferential direction S between the spring holder 54 and the oil discharge hole 45F is less than or equal to a length L5" means that the spring holder 54 and the oil discharge hole 45F may be separated by a distance of less than or equal to a length L5, and at least a portion of the oil discharge hole 45F may overlap with the spring holder 54 in the circumferential direction S. The distance in the circumferential direction S between the oil discharge hole 45F and the first support side surface 54B of the spring holder 54 located on the second circumferential direction S2 side of the oil discharge hole 45F is different for each oil discharge hole 45F1, 45F2, and 45F3. However, this distance may be the same for each oil discharge hole 45F1, 45F2, and 45F3. The number of oil discharge holes 45F provided in a single spline groove 48 (see Figure 6) is not particularly limited.For example, two or more oil discharge holes 45F may be formed in a single spline groove 48.

[0035] As shown in Figure 6, the oil discharge holes 45F1, 45F2, and 45F3 are located at different positions in the axial direction D. In this embodiment, the oil discharge holes 45F1, 45F2, and 45F3 are arranged at equal intervals from right R to left L in the order of oil discharge holes 45F1, 45F2, and 45F3. At least a portion of the oil discharge holes 45F overlaps with the output side rotating plate 22 (see Figure 7) in the axial direction D. The position of at least a portion of the oil discharge holes 45F in the axial direction D is the same as the position of at least a portion of the output side rotating plate 22 in the axial direction D. For example, as shown in Figure 7, the oil discharge hole 45F1 and the output side rotating plate 22N, which is located furthest to the right R of the output side rotating plate 22, are at least partially in the same position with respect to the axial direction D. In this embodiment, the midpoint of the oil discharge hole 45F1 in the axial direction D and the midpoint of the output side rotating plate 22N in the axial direction D are approximately coincident. Although detailed illustrations are omitted, at least a portion of the oil discharge hole 45F2 (see Figure 6) overlaps with the output side rotating plate 22M adjacent to the left of the output side rotating plate 22N in the axial direction D. At least a portion of the oil discharge hole 45F3 (see Figure 6) overlaps with the output side rotating plate 22L adjacent to the left of the output side rotating plate 22M in the axial direction D.

[0036] When the clutch center 40 rotates in the first circumferential direction S1, the oil flows in the second circumferential direction S2 along the inner circumferential surface of the outer cylinder portion 45 shown in Figure 6. The oil flowing in the second circumferential direction S2 is blocked by the first support side surface 54B of the spring holder 54. Since the oil discharge hole 45F is close to the spring holder 54 on the first circumferential direction S1 side, specifically, the distance between the spring holder 54 and the oil discharge hole 45F in the circumferential direction S is less than or equal to the length L5 (see Figure 5) of the radial direction Q of the spring holder 54, at least a portion of the oil blocked by the first support side surface 54B is smoothly discharged to the outside of the clutch center 40 through the oil discharge hole 45F. This allows oil to be supplied to the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 1). The oil discharge holes 45F1, 45F2, and 45F3, each provided on the first circumferential direction S1 side of the multiple spring holders 54, are located at different positions in the axial direction D. This ensures that oil can be reliably supplied to the input-side rotating plate 20 and the output-side rotating plate 22, which are located at different positions in the axial direction D. As shown in Figure 7, one of the oil discharge holes 45F (e.g., oil discharge hole 45F1) and one of the output-side rotating plates 22 (e.g., output-side rotating plate 22N) are at least partially in the same position with respect to the axial direction D. This ensures that oil can be reliably supplied to one of the output-side rotating plates 22 (e.g., output-side rotating plate 22N). Furthermore, since multiple oil discharge holes 45F (oil discharge hole 45F1, oil discharge hole 45F2 (see Figure 6), oil discharge hole 45F3 (see Figure 6)) are located at least partially in the same position as each output-side rotating plate 22 (22N, 22M, 22L) with respect to the axial direction D, oil can be reliably supplied to all output-side rotating plates 22.

[0037] As shown in Figure 1, the pressure spring 25 is positioned radially Q inward from the spring holder 54. Inside the pressure spring 25 is the boss portion 84 of the pressure plate 70, which will be described later. The left end 25L of the pressure spring 25 is in contact with the disc portion 44 of the clutch center 40. The pressure spring 25 is, for example, a coil spring made by winding spring steel in a spiral shape.

[0038] As shown in Figure 1, the pressure plate 70 is housed in the clutch housing 30. The pressure plate 70 is located between the clutch housing 30 and the clutch center 40 with respect to the axial direction D. The pressure plate 70 is provided so as to be able to move toward and away from the clutch center 40. The pressure plate 70 is provided so as to be able to rotate relative to the clutch center 40. The pressure plate 70 is configured to be able to press against the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 70 is arranged concentrically with the clutch center 40 and the clutch housing 30. As shown in Figure 8, the pressure plate 70 has a pressure plate body 72 and a flange 98. The pressure plate 70 does not hold the output side rotating plate 22 (see Figure 1). However, the pressure plate teeth 77 may be configured to hold at least one of the output side rotating plates 22.

[0039] A fitting hole 80 is formed in the center of the pressure plate body 72. The fitting hole 80 penetrates the pressure plate body 72 in the axial direction D. The output shaft holding portion 50 (see Figure 2) of the clutch center 40 (see Figure 2) is inserted into the fitting hole 80. The fitting hole 80 is externally fitted onto the output shaft holding portion 50.

[0040] The pressure plate 70 has a plurality (10 in this embodiment) of pressure plate teeth 77. In this embodiment, the pressure plate teeth 77 are provided on the pressure plate body 72. The inner surface of the pressure plate teeth 77 in the radial direction Q is the tooth tip of the pressure plate tooth 77. The pressure plate body 72 has intertooth portions 72P formed between adjacent pressure plate teeth 77. The intertooth portions 72P are the spaces between adjacent pressure plate teeth 77. The intertooth portions 72P penetrate in the radial direction Q. The pressure plate body 72 has an intertooth surface 72A formed between the pressure plate teeth 77 and a connecting surface 72B located radially Q inward from the intertooth surface 72A and radially Q outward from the fitting hole 80. The intertooth surface 72A and the connecting surface 72B are the right side (right R side) surfaces of the pressure plate body 72. In Figures 9A and 9B, the boundary between the intertooth surface 72A and the connecting surface 72B is shown by a dashed line. The outer edge of the intertooth surface 72A is connected to the flange 98. The intertooth surface 72A and the connecting surface 72B are formed to be approximately flush. Here, "approximately flush" includes a state in which the surfaces are completely flush with no steps whatsoever, and a state in which there is a step of about 0 mm to 0.3 mm between the surfaces but they are still approximately flush. In this embodiment, the intertooth surface 72A and the connecting surface 72B are formed to be completely flush. The pressure plate teeth 77 may be provided on the flange 98.

[0041] As shown in Figures 8 and 9A, the flange 98 extends radially outward from the pressure plate body 72 in the direction Q. As shown in Figure 1, the flange 98 of the pressure plate 70 contacts and presses the input-side rotating plate 20L located furthest left L among the plurality of input-side rotating plates 20. The flange 98 is provided so as to be able to press the input-side rotating plate 20 and the output-side rotating plate 22. The flange 98 is a member that applies pressing force to the input-side rotating plate 20 and the output-side rotating plate 22.

[0042] The pressure plate teeth 77 extend to the right R of the flange 98 (see Figure 8). As shown in Figure 9A, the pressure plate teeth 77 are aligned in the circumferential direction S. The spacing between adjacent pressure plate teeth 77 in the circumferential direction S is not uniform. The intertooth surface 72A has first to third intertooth surfaces 72A1 to 72A3 with different lengths in the circumferential direction S. The first intertooth surface 72A1 is the surface between two adjacent pressure plate teeth 77 at the first pitch P1. The second intertooth surface 72A2 is the surface between two adjacent pressure plate teeth 77 at the second pitch P2. The third intertooth surface 72A3 is the surface between two adjacent pressure plate teeth 77 at the third pitch P3. In this embodiment, the number of first intertooth surfaces 72A1, second intertooth surfaces 72A2, and third intertooth surfaces 72A3 are 5, 1, and 4, respectively. The second pitch P2 is longer than the first pitch P1. The third pitch P3 is longer than the second pitch P2. The circumferential length L8 of the second intertotal surface 72A2 is longer than the circumferential length L7 of the first intertotal surface 72A1. The circumferential length L9 of the third intertotal surface 72A3 is longer than the circumferential length L8 of the second intertotal surface 72A2. Lengths L8 and L9 are longer than the spacing L20 (see Figure 10) between adjacent rotating plate teeth 22b (see Figure 10). The second intertotal surface 72A2 and the third intertotal surface 72A3 are surfaces that appear to have missing pressure plate teeth 77, and are examples of missing tooth surfaces of the present invention. The second intertotal surface 72A2 is a surface that appears to have four missing pressure plate teeth 77 compared to the case where the intertotal surface 72A has only the first intertotal surface 72A1 and the pressure plate teeth 77 are arranged at equal intervals. Similarly, the third intertotal surface 72A3 is a surface that appears to have five pressure plate teeth 77 missing. The pressure plate 70 appears to have a total of 24 pressure plate teeth 77 missing. In this embodiment, with respect to the circumferential direction S, the first intertotal surface 72A1 is located between the second intertotal surface 72A2 and the third intertotal surface 72A3, or between two adjacent third intertotal surfaces 72A3. However, the number and arrangement of the first intertotal surface 72A1, the second intertotal surface 72A2, and the third intertotal surfaces 72A3 are not limited thereto.

[0043] Adjacent pressure plate teeth 77 at the first pitch P1 are an example of first pressure plate teeth in the present invention. Adjacent pressure plate teeth 77 at the second pitch P2 are an example of second pressure plate teeth in the present invention. Adjacent pressure plate teeth 77 at the third pitch P3 are an example of third pressure plate teeth in the present invention. In this embodiment, a first pressure plate tooth also corresponds to a second pressure plate tooth or a third pressure plate tooth. More specifically, one of the first pressure plate teeth located on the first circumferential direction S1 side is adjacent to a pressure plate tooth 77 located on the first circumferential direction S1 side from the perspective of that first pressure plate tooth at the second pitch P2 or third pitch P3, and therefore also corresponds to a second pressure plate tooth or a third pressure plate tooth. The same applies to the other of the first pressure plate teeth located on the second circumferential direction S2 side. In this embodiment, with respect to the circumferential direction S, the first intertotal surface 72A1 is positioned between the second intertotal surface 72A2 and the third intertotal surface 72A3, or between two adjacent third intertotal surfaces 72A3. Therefore, the second pressure plate teeth do not also correspond to the third pressure plate teeth. However, the second pressure plate teeth may also correspond to the third pressure plate teeth.

[0044] As shown in FIG. 1, the input-side rotating plate 20L located at the leftmost position L is positioned outside the pressure plate teeth 77 in the radial direction Q. The pressure plate teeth 77 overlap with the input-side rotating plate 20L located at the leftmost position L in the axial direction D. The pressure plate teeth 77 do not overlap with the output-side rotating plate 22 in the axial direction D. As shown in FIG. 10, in the present embodiment, among the 34 rotating plate teeth 22b of the output-side rotating plate 22, 10 rotating plate teeth 22b overlap with the 10 pressure plate teeth 77 when viewed in the axial direction D. The number of the pressure plate teeth 77 is smaller than the number of the rotating plate teeth 22b of the output-side rotating plate 22. When viewed in the axial direction D, the first tooth gap surface 72A1 does not overlap with the rotating plate teeth 22b. When viewed in the axial direction D, the first tooth gap surface 72A1 overlaps with the rotating plate groove 22c. When viewed in the axial direction D, the second tooth gap surface 72A2 overlaps with four rotating plate teeth 22b. When viewed in the axial direction D, the third tooth gap surface 72A3 overlaps with five rotating plate teeth 22b. As shown in FIG. 9A, the reference sign L10 represents the length in the circumferential direction S at the tooth root (the outer end in the radial direction Q) of the pressure plate teeth 77. The sum L8 + 4×L9 of the length L8 in the circumferential direction S of the second tooth gap surface 72A2 and the lengths L9 in the circumferential direction S of a plurality (in this embodiment, 4) of the third tooth gap surfaces 72A3 is longer than the sum 10×L10 of the lengths L10 in the circumferential direction S of a plurality (in this embodiment, 10) of the pressure plate teeth 77. The total length L8 + 4×L9 is 2.5 times or more and 10 times or less the total length 10×L10.

[0045] As shown in FIG. 9A, when viewed from the right side R, the pressure plate 70 is divided into four equal parts by a straight line SL1 passing through the axis CL1 and a straight line SL2 orthogonal to the straight line SL1, namely, a first region T1, a second region T2, a third region T3, and a fourth region T4. Each of the first region T1, the second region T2, the third region T3, and the fourth region T4 includes at least a part of the second tooth gap surface 72A2 (and a second tooth gap portion 72P2 described later) or the third tooth gap surface 72A3 (and a third tooth gap portion 72P3 described later). The straight line SL1 is an example of a first straight line. The straight line SL2 is an example of a second straight line.

[0046] As shown in Figure 9B, the interdental portion 72P has first to third interdental portions 72P1 to 72P3 with different circumferential lengths S. In this embodiment, the circumferential length S of the first interdental portion 72P1 is the same as the circumferential length S L7 of the first interdental surface 72A1. The circumferential length S of the second interdental portion 72P2 is the same as the circumferential length S L8 of the second interdental surface 72A2. The circumferential length S of the third interdental portion 72P3 is the same as the circumferential length S L9 of the third interdental surface 72A3. The sum of the circumferential length S L8 of the second interdental portion 72P2 and the circumferential lengths S L9 of the multiple (4 in this embodiment) third interdental portions 72P3, L8 + 4 × L9, is longer than the sum of the circumferential lengths S L10 of the multiple (10 in this embodiment) pressure plate teeth 77, 10 × L10. The total length L8 + 4 × L9 is between 2.5 and 10 times the total length 10 × L10. The second interdental space 72P2 and the third interdental space 72P3 are spaces where the pressure plate teeth 77 appear to be missing, and are examples of missing teeth in the present invention.

[0047] As shown in Figure 9, when viewed in the axial direction D of the output shaft 15, there exists a pressure plate line LP that passes through the center 70C of the pressure plate 70, bisects the pressure plate 70 into a first pressure plate region PT1 and a second pressure plate region PT2, and in the first pressure plate region PT1 and the second pressure plate region PT2, the multiple pressure plate teeth 77 and the multiple intertotal portions 72P are not symmetrical. When viewed in the axial direction D of the output shaft 15, if the pressure plate 70 is divided into a first pressure plate region PT1 and a second pressure plate region PT2 by a pressure plate line LP passing through the center 70C of the pressure plate 70, then the multiple pressure plate teeth 77 and multiple intertooth portions 72P in the first pressure plate region PT1 and the second pressure plate region PT2 are not symmetrical with respect to the pressure plate line LP. For example, in the example shown in Figure 9B, the pressure plate line LP passes through the third intertooth portion 72P3, the number of pressure plate teeth 77 in the first pressure plate region PT1 is 6, and the number of pressure plate teeth 77 in the second pressure plate region PT2 is 4.

[0048] As shown in FIG. 11, when the pressure plate 70 and the clutch center 40 are assembled, the pressure plate teeth 77 are positioned at positions where they can mesh with the first circumferential direction S1 side and the second circumferential direction S2 side of the clutch center teeth 47. FIG. 12 is a cross-sectional view of the A-A cross-section in FIG. 11. As shown in FIG. 12, in the present embodiment, the pressure plate teeth 77 are fitted into the first spline groove 48A and do not mesh with the second spline groove 48B and the third spline groove 48C. However, the number and arrangement of the pressure plate teeth 77 are not limited to this.

[0049] As shown in FIG. 1, the symbol L11 represents the length in the axial direction D of the pressure plate teeth 77. The right end 77R of the pressure plate teeth 77 is located to the right R of the left end 20La of the input-side rotating plate 20L located most to the left L among the plurality of input-side rotating plates 20, and is located to the left L of the left end 22La of the output-side rotating plate 22L located most to the left L among the plurality of output-side rotating plates 22. The input-side rotating plate 20L is an example of the first input-side rotating plate in the present invention. The output-side rotating plate 22L is an example of the first output-side rotating plate in the present invention.

[0050] As shown in Figures 8 and 9A, the connection surface 72B of the pressure plate 70 is provided with a plurality of (three in this embodiment) boss portions 84. The plurality of boss portions 84 are arranged at equal intervals in the circumferential direction S. The boss portions 84 are formed in a cylindrical shape. As shown in Figure 10, the three boss portions 84 will also be referred to as boss portions 84A, 84B, and 84C, respectively. However, when providing a description common to all of boss portions 84A, 84B, and 84C, the name boss portion 84 will be used as appropriate. The boss portions 84 are located radially Q outward from the fitting hole 80. The boss portions 84 extend to the right R from the connection surface 72B of the pressure plate body 72 (see also Figure 8). In this embodiment, as shown in Figure 1, the boss portion 84 extends to the right R from the flange 68 of the clutch center 40. The boss portions 84 have fastening holes 84H into which bolts 28 are inserted. The fastening hole 84H extends in the axial direction D. As shown in Figure 12, when the pressure plate 70 and the clutch center 40 are assembled coaxially, the boss portion 84 is positioned inside the first through hole 44a of the clutch center 40 and penetrates the first through hole 44a in the axial direction D. A virtual circle CR4, centered on axis CL1 and passing through the center 84E of the boss portion 84, passes through the center 44C1 of the first through hole 44a. The radial distance Q between axis CL1 and the center 84E of the boss portion 84 is R4 (see also Figure 4), similar to the radial distance Q between axis CL1 and the center 44C1 of the first through hole 44a. As described above, the innermost end 44bN in the radial direction Q of the second through hole 44b is located radially outside Q than the innermost end 44aN in the radial direction Q of the first through hole 44a. A virtual circle CR5, centered on axis CL1 and passing through the innermost end 84N in the radial direction Q of the boss portion 84, is located inward in the radial direction Q than a virtual circle CR3 passing through the innermost end 44bN of the second through hole 44b. Therefore, even if the circumferential position S of the boss portion 84 and the circumferential position S of the second through hole 44b are aligned, the boss portion 84 cannot penetrate the second through hole 44b in the axial direction D, and the pressure plate 70 and the clutch center 40 cannot be assembled. However, the structure in which the boss portion 84 cannot penetrate the second through hole 44b in the axial direction D is not limited to this. For example, the diameter of the second through hole 44b may be shorter than the diameter of the boss portion 84.In this case, the positions of the center 44C1 of the first through hole 44a and the center 44C2 of the second through hole 44b in the radial direction Q may be the same. Alternatively, the shape of the second through hole 44b may be a shape other than a circle. For example, the second through hole 44b may be formed in a rectangular shape such that, in a plan view, the length of the opposing sides is shorter than the diameter of the boss portion 84.

[0051] Figure 10 shows a straight line SL3 passing through the axis CL1 and the end 84a of the boss portion 84A on the first circumferential direction S1 side, and a straight line SL4 passing through the axis CL1 and the end 84b of the boss portion 84A on the second circumferential direction S2 side. With respect to the circumferential direction S, a part of the third intertooth surface 72A3 (and the third intertooth portion 72P3) is located between the straight line SL3 and the straight line SL4. At least a part of the second intertooth surface 72A2 (and the second intertooth portion 72P2) may also be located between the straight line SL3 and the straight line SL4. In the case of a plurality of boss portions 84 as in this embodiment, it is sufficient that the above positional relationship holds for at least one boss portion 84 and the second intertooth surface 72A2 (and the second intertooth portion 72P2) or the third intertooth surface 72A3 (and the third intertooth portion 72P3). Furthermore, Figure 10 shows a straight line SL5 passing through the axis CL1 and the center of the boss portion 84A. Straight line SL5 passes through the third intertooth surface 72A3 (third intertooth portion 72P3). Alternatively, straight line SL5 may pass through the second intertooth surface 72A2 (second intertooth portion 72P2). Although detailed illustration is omitted, a straight line passing through the axis CL1 and the center of the boss portion 84B also passes through the third intertooth surface 72A3 (and the third intertooth portion 72P3). On the other hand, straight line SL6 passing through the axis CL1 and the center of the boss portion 84C passes through the first intertooth surface 72A1 (and the first intertooth portion 72P1) but does not pass through the second intertooth surface 72A2 (and the second intertooth portion 72P2) or the third intertooth surface 72A3 (and the third intertooth portion 72P3). In this embodiment, if there are multiple boss portions 84, it is sufficient that the boss portions 84 are arranged such that a straight line passing through the center of at least one boss portion 84 and the axis CL1 passes through a missing tooth surface (and missing tooth portion) where the pressure plate teeth 77 are missing, for example, the second intertooth surface 72A2 (and the second intertooth portion 72P2) or the third intertooth surface 72A3 (and the third intertooth portion 72P3).

[0052] As shown in Figure 8, a plurality (six in this embodiment) of third through holes 74 are formed in the connection surface 72B of the pressure plate body 72. The third through holes 74 are located on the first circumferential direction S1 side and the second circumferential direction S2 side of one boss portion 84, respectively. The third through holes 74 penetrate the connection surface 72B in the axial direction D. As shown in Figure 12, the center 74C of the third through hole 74 in the radial direction Q is located radially outward Q than the center 44C2 of the second through hole 44b. When the clutch center 40 and the pressure plate 70 are assembled so that the boss portion 84 penetrates the first through hole 44a, the third through hole 74 overlaps with at least a portion of the second through hole 44b when viewed from the right R. In this embodiment, the third through holes 74 are arranged such that, in the circumferential direction S, the midpoint between the centers 74C of two adjacent third through holes 74 is the position of the center 44C2 of one second through hole 44b. However, the number and arrangement of the third through-holes 74 are not limited thereto.

[0053] As shown in Figure 1, the support plate 100 is located to the right R of the clutch center 40. The support plate 100 is a member that holds the pressure spring 25 together with the clutch center 40. The support plate 100 is a member that displaces the pressure plate 70 in the axial direction D. The support plate 100 is fixed to the pressure plate 70 by bolts 28. More specifically, the support plate 100 is fixed to the boss portion 84 of the pressure plate 70 by bolts 28. The support plate 100 rotates integrally with the pressure plate 70. The support plate 100 moves in the axial direction D relative to the clutch center 40 and rotates relative to the clutch center 40. The support plate 100 is operated by a clutch release mechanism (not shown). Here, the clutch release mechanism is a mechanical device that operates in a vehicle such as a motorcycle equipped with a clutch device 10 by the operation of the driver's clutch operation lever (not shown). The clutch release mechanism may be electrically operated by a servo motor or the like. The support plate 100 has a through hole 100H that penetrates in the axial direction D. The nut 15N can be accessed through the through hole 100H.

[0054] Here, the operation of the pressure plate teeth 77 will be explained. When the clutch release mechanism is operated and the spring force of the pressure spring 25 moves the support plate 100 and the pressure plate 70 to the right R, the input side rotating plate 20L and the output side rotating plate 22 are pressed against each other, resulting in what is known as the clutch being ON. Figure 1 shows the clutch ON state. In this state, when the engine speed increases, the rotational driving force of the input shaft is transmitted to the output shaft 15 via the input side rotating plate 20L, the output side rotating plate 22 and the clutch center 40. At this time, the rotational driving force is transmitted to the pressure plate 70 from the input side rotating plate 20L, which is located at the leftmost position L. When the clutch is ON, with respect to the axial direction D, the position of the right end 77R of the pressure plate teeth 77 is approximately the same as the position of the right end of the input side rotating plate 20L. However, when the clutch is ON, the right end 77R of the pressure plate teeth 77 may be located to the left L of the right end of the input side rotating plate 20L.

[0055] When rotational driving force is transmitted from the input-side rotating plate 20L, located at the leftmost position L, to the pressure plate 70, as shown in Figure 13A, at least a portion of the pressure plate teeth 77 located on the second circumferential direction S2 side of the clutch center teeth 47 engages with the side surface 47G of the clutch center teeth 47 on the second circumferential direction S2 side. Therefore, the clutch center 40 receives rotational driving force not only from the pressing of the input-side rotating plate 20 (see Figure 1) and the output-side rotating plate 22 (see Figure 1), but also from the pressure plate 70 via the clutch center teeth 47 and the pressure plate teeth 77. As a result, the rotational driving force of the input shaft is reliably transmitted to the clutch center 40 and, consequently, to the output shaft 15 (see Figure 1).

[0056] On the other hand, when the rotational speed of the output shaft 15 shown in Figure 1 exceeds the rotational speed of the input gear 35 and the clutch housing 30, back torque is generated. At this time, the clutch center 40 rotates at a faster rotational speed than the pressure plate 70, so, as shown in Figure 13B, at least a portion of the clutch center teeth 47 located on the second circumferential direction S2 side of the pressure plate teeth 77 engages with the side surface 77G of the pressure plate teeth 77 on the second circumferential direction S2 side. Therefore, the clutch housing 30 shown in Figure 1 receives rotational force not only from the pressing of the input side rotating plate 20 and the output side rotating plate 22, but also from the pressure plate 70 and the input side rotating plate 20L located on the far left L, due to the engagement of the clutch center teeth 47 and the pressure plate teeth 77. As a result, the rotational driving force of the output shaft 15 is reliably transmitted to the clutch housing 30 and, consequently, to the input shaft, ensuring that the engine brake is effectively applied.

[0057] As described above, according to the clutch device 10 of this embodiment, as shown in Figure 10, the number of pressure plate teeth 77 is less than the number of rotation plate teeth 22b of the output side rotating plate 22. Compared to the case where the number of pressure plate teeth 77 and the number of rotation plate teeth 22b are the same, the number of pressure plate teeth 77 is less. As a result, in the clutch device 10 in which at least a portion of the pressure plate teeth 77 overlap with the input side rotating plate 20 (see Figure 1) in the radial direction Q, the weight of the pressure plate 70 can be reduced.

[0058] In the clutch device 10 of this embodiment, as shown in Figure 9A, the second intertooth surface 72A2 and the third intertooth surface 72A3 (missing tooth surface) and the connecting surface 72B are formed to be substantially flush. There is no step between the second intertooth surface 72A2 and the third intertooth surface 72A3 and the connecting surface 72B. Therefore, when oil flows radially outward in the direction Q from the connecting surface 72B of the pressure plate 70 toward the second intertooth surface 72A2 and the third intertooth surface 72A3, the flow of oil is relatively unobstructed. As a result, oil can be discharged to the outside of the pressure plate 70 more reliably.

[0059] In the clutch device 10 of this embodiment, as shown in Figure 9A, the sum of the circumferential length L8 of the second intertotal surface 72A2 and the circumferential length L9 of the multiple third intertotal surfaces 72A3, L8 + 4 × L9, is longer than the sum of the circumferential lengths L10 of the multiple pressure plate teeth 77, which is 10 × L10. The total length L8 + 4 × L9 is between 2.5 and 10 times the total length 10 × L10. The proportion of the intertotal surfaces 72A that are missing teeth, namely the second intertotal surface 72A2 and the third intertotal surface 72A3, is relatively high. As a result, the pressure plate 70 can be made lighter.

[0060] In the clutch device 10 of this embodiment, as shown in Figure 10, a portion of the third intertooth surface 72A3 is positioned between the straight line SL3 and the straight line SL4. The straight line SL5 passes through the third intertooth surface 72A3. The third intertooth surface 72A3 is located between the pressure plate teeth 77 and has a relatively long length S in the circumferential direction. Therefore, when the oil flows outward in the radial direction Q, passing relatively close to the boss portion 84, the flow of oil is less likely to be obstructed by the pressure plate teeth 77. This allows for a more reliable supply of oil to the input side rotating plate 20 and the output side rotating plate 22.

[0061] According to the clutch device 10 of this embodiment, as shown in Figure 9A, the pressure plate teeth 77 include adjacent pressure plate teeth 77 at a first pitch P1, adjacent pressure plate teeth 77 at a second pitch P2, and adjacent pressure plate teeth 77 at a third pitch P3. The length L8 in the circumferential direction S of the second intertooth surface 72A2 is longer than the length L7 in the circumferential direction S of the first intertooth surface 72A1. The length L9 in the circumferential direction S of the third intertooth surface 72A3 is longer than the length L8 in the circumferential direction S of the second intertooth surface 72A2. The multiple pressure plate teeth 77 arranged in the circumferential direction S are arranged at irregular positions (uneven positions). Compared to the case where the pressure plate teeth 77 are arranged at equal intervals, the number of pressure plate teeth 77 is smaller, so the pressure plate 70 can be made lighter.

[0062] In the clutch device 10 of this embodiment, as shown in Figure 4, the length L3 in the circumferential direction S of the second spline groove 48B is longer than the length L2 in the circumferential direction S of the first spline groove 48A. The length L4 in the circumferential direction S of the third spline groove 48C is longer than the length L3 in the circumferential direction S of the second spline groove 48B. The clutch center teeth 47 are arranged in irregular positions (uneven positions). Compared to the case where the clutch center teeth 47 are arranged at equal intervals, the number of clutch center teeth 47 is smaller, so the clutch center 40 can be made lighter.

[0063] In the clutch device 10 of this embodiment, as shown in Figure 1, the length L1 in the axial direction D of the clutch center teeth 47 is longer than the length L11 in the axial direction D of the pressure plate teeth 77. Compared to the case where the length in the axial direction D of the pressure plate teeth 77 is greater than or equal to the length in the axial direction D of the clutch center teeth 47, the pressure plate 70 can be made more compact. As a result, the pressure plate 70 can be made lighter.

[0064] According to the clutch device 10 of this embodiment, as shown in Figure 9A, the first region T1, second region T2, third region T3, and fourth region T4 of the pressure plate 70 each include at least a portion of the second intertooth surface 72A2 or the third intertooth surface 72A3. The proportion of the intertooth surface 72A that is occupied by the second intertooth surface 72A2 or the third intertooth surface 73A3, which are missing teeth of the pressure plate teeth 77, is relatively high. As a result, the pressure plate 70 can be made lighter.

[0065] In the embodiment described above, as shown in Figure 10, the number of pressure plate teeth 77 was less than the number of rotating plate teeth 22b of the output side rotating plate 22. However, the number of pressure plate teeth 77 may be the same as the number of rotating plate teeth 22b, or greater than or equal to the number of rotating plate teeth 22b. Regardless of the number of pressure plate teeth 77 relative to the number of rotating plate teeth 22b, the number of pressure plate teeth 77 can be relatively reduced by having a first intertooth surface 72A1 and a second intertooth surface 72A2 and / or a third intertooth surface 72A3, which have a longer circumferential length S than the first intertooth surface 72A1. This makes it possible to lighten the pressure plate 70.

[0066] <Second Embodiment> Figure 14 is a view of the clutch center 140 according to the second embodiment, viewed from the left L. The clutch center 140 is housed in the clutch housing 30 (see Figure 1). The clutch center 140 is arranged concentrically with the clutch housing 30. The clutch center 140 includes an output shaft holding portion 50 held on the output shaft 15 (see Figure 1), an outer cylindrical portion 145 located radially Q outward from the output shaft holding portion 50, a disc portion 144 connected to the output shaft holding portion 50 and the outer cylindrical portion 145, and an annular flange 68 located radially Q outward from the outer cylindrical portion 145.

[0067] The outer cylinder portion 145 is provided with a spline fitting portion 146. The spline fitting portion 146 has a plurality of clutch center teeth 147 extending in the axial direction D (see Figure 1) and a plurality of spline grooves 148 formed between adjacent clutch center teeth 47.

[0068] Multiple (16 in this embodiment) clutch center teeth 147 are arranged in the circumferential direction S. Multiple clutch center teeth 147 are formed to have the same shape. The clutch center teeth 147 protrude outward from the outer cylinder portion 145 in the radial direction Q. The clutch center teeth 147 hold the output side rotating plate 22 (see Figure 1). Multiple clutch center teeth 147 are formed at non-uniform positions with respect to the circumferential direction S. The number of clutch center teeth 147 (16 in this embodiment) is less than the number of rotating plate teeth 22b (see Figure 16) of the output side rotating plate 22 (see Figure 16) (see Figure 16) (see Figure 16).

[0069] Multiple spline grooves 148 are arranged in the circumferential direction S. The spline groove 148 includes multiple spline grooves 148A, 148B, and 148C with different lengths in the circumferential direction S. The spline groove 148 has multiple (2 in this embodiment) first spline grooves 148A, multiple (10 in this embodiment) second spline grooves 148B, and multiple (4 in this embodiment) third spline grooves 148C. In this embodiment, the proportion of first spline grooves 148A among the multiple spline grooves 148 is less than 20%. In this embodiment, there are 2 first spline grooves 148A among 16 spline grooves 148, and the proportion of first spline grooves 148A among the multiple spline grooves 148 is approximately 12%. Reference numerals L12, L13, and L14 represent the lengths in the circumferential direction S of the first spline groove 148A, the second spline groove 148B, and the third spline groove 148C, respectively. The length L13 of the second spline groove 148B is longer than the length L12 of the first spline groove 148A. The length L14 of the third spline groove 148C is longer than the length L13 of the second spline groove 148B. Lengths L13 and L14 are longer than the length L20 (see Figure 16), which is the distance between adjacent rotating plate teeth 22b (see Figure 16) of the output side rotating plate 22 (see Figure 16). The second spline groove 148B and the third spline groove 148C are examples of toothless grooves in the present invention. In this embodiment, with respect to the circumferential direction S, the second spline groove 148B is not positioned between the first spline groove 148A and the third spline groove 148C. With respect to the circumferential direction S, the first spline groove 148A and the third spline groove 148C are arranged adjacent to each other. More specifically, with respect to the circumferential direction S, the first spline groove 148A and the third spline groove 148C are arranged adjacent to each other with the clutch center tooth 147 in between.

[0070] As shown in Figure 14, when viewed in the axial direction D of the output shaft 15, there exists a straight line LC that passes through the center 140C of the clutch center 140, bisects the clutch center 140 into a first region CT1 and a second region CT2, and in the first region CT1 and the second region CT2, the multiple clutch center teeth 147 and the multiple spline grooves 148 are not symmetrical with respect to the straight line LC. When the clutch center 140 is bisected into a first region CT1 and a second region CT2 by the straight line LC passing through the center 140C of the clutch center 140 when viewed in the axial direction D of the output shaft 15, the multiple clutch center teeth 147 and the multiple spline grooves 148 in the first region CT1 and the second region CT2 are not symmetrical with respect to the straight line LC. For example, in the example shown in Figure 14, the straight line LC passes through the third spline groove 48C and the third spline groove 148C.

[0071] The clutch center teeth 147 have a pair of sides facing each other in the circumferential direction S. Of the pair of sides of the clutch center teeth 147, the multiple sides (14 in this embodiment) located on the first circumferential direction S1 side and connected to the outer cylinder portion 145 are referred to as the first side 147F. Of the pair of sides of the clutch center teeth 147, the multiple sides (14 in this embodiment) located on the second circumferential direction S2 side and connected to the outer cylinder portion 145 are referred to as the second side 147G.

[0072] Figure 15 is a view of the pressure plate 170 according to the second embodiment, viewed from the right R. The pressure plate 170 is housed in the clutch housing 30 (see Figure 1). The pressure plate 170 is provided so as to be able to approach or move away from the clutch center 140 (see Figure 14) and to be able to rotate relative to it. The pressure plate 170 is configured to be able to press the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 1). The pressure plate 170 is arranged concentrically with the clutch center 140 and the clutch housing 30. The pressure plate 170 has a pressure plate body 172 and a flange 98. The pressure plate 170 does not hold the output side rotating plate 22. A fitting hole 80 is formed in the center of the pressure plate body 172 into which the output shaft holding portion 50 (see Figure 14) of the clutch center 140 is inserted.

[0073] The pressure plate 170 has a plurality (17 in this embodiment) of pressure plate teeth 177. The inner surface of the pressure plate teeth 177 in the radial direction Q is the tooth tip of the pressure plate teeth 177. The pressure plate body 172 has an intertooth surface 172A formed between the pressure plate teeth 177 and a connecting surface 172B located radially Q inward from the intertooth surface 172A and radially Q outward from the fitting hole 80. The intertooth surface 172A and the connecting surface 172B are the right-hand R side surfaces of the pressure plate body 172. The outer periphery of the intertooth surface 172A is connected to the flange 98. The pressure plate teeth 177 extend to the right R beyond the flange 98. The pressure plate teeth 177 are aligned in the circumferential direction S. Unlike the pressure plate teeth 77 (see Figure 9A) in one embodiment, the pressure plate teeth 177 are arranged at equal intervals. The circumferential length L15 of the intertooth surface 172A is longer than the circumferential spacing L20 (see Figure 16) between adjacent rotating plate teeth 22b (see Figure 16) of the output side rotating plate 22 (see Figure 16). As shown in Figure 16, the fourth pitch P4 of two adjacent pressure plate teeth 177 is twice the pitch of the fifth pitch P5 of adjacent rotating plate teeth 22b. The intertooth surface 172A is a surface that appears as if one pressure plate tooth 77 is missing, and constitutes a missing tooth surface. When viewed in the axial direction D (see also Figure 15), the rotating plate teeth 22b and the pressure plate teeth 177 overlap. In this embodiment, when viewed in the axial direction D, pressure plate teeth 177 that overlap with the rotating plate teeth 22b and pressure plate teeth 177 that do not overlap with the rotating plate teeth 22b are arranged alternately in the circumferential direction S.

[0074] Figure 17 shows the pressure plate 170 and the clutch center 140 assembled. The multiple (17 in this embodiment) pressure plate teeth 177 have multiple (8 in this embodiment) first fitting teeth 177A that abut against the first side surface 147F of the clutch center teeth 147 (the side surface of the clutch center 140 on the rotational direction S1 side) and multiple (8 in this embodiment) second fitting teeth 177B that abut against the second side surface 147G of the clutch center teeth 147 (the side surface of the clutch center 140 on the counter-rotational direction S2 side). One of the pressure plate teeth 177 abuts against both the first side surface 147F and the second side surface 147G (i.e., it is both a first fitting tooth 177A and a second fitting tooth 177B). In this embodiment, there are a plurality (2 in this embodiment) of pressure plate teeth 177 that do not contact either the first side surface 147F or the second side surface 147G.

[0075] As shown in Figure 17, when the pressure plate 170 is divided into a first region T11 and a second region T12 by a straight line SL7 passing through axis CL1 when viewed from the right R, the number of first mating teeth 177A and the number of second mating teeth 177B are different in the first region T11 and the second region T12. In this embodiment, the first region T11 contains seven first mating teeth 177A and one second mating tooth 177B. The second region T12 contains one first mating tooth 177A and seven second mating teeth 177B. However, the number of first mating teeth 177A and second mating teeth 177B included in the first region T11 and the second region T12 is not limited to these. In either the first region T11 or the second region T12, the number of first mating teeth 177A and the number of second mating teeth 177B may be different.

[0076] In the clutch device 10 of this embodiment, the plurality of pressure plate teeth 177 have a first fitting tooth 177A and a second fitting tooth 177B. During normal driving, the second side surface 147G of the clutch center tooth 147 receives rotational driving force from the surface of the pressure plate tooth 177 on the first circumferential direction S1 side. When the rotational speed of the output shaft 15 (see Figure 1) exceeds the rotational speed of the input gear 35 (see Figure 1) and the clutch housing 30 (see Figure 1), and back torque is generated, the first fitting tooth 177A receives rotational driving force from the first side surface 147F of the clutch center tooth 147. This ensures that the rotational driving force of the input shaft is reliably transmitted to the output shaft 15 during normal driving, and that the engine brake is reliably applied when back torque is generated.

[0077] In the clutch device 10 of this embodiment, the number of first fitting teeth 177A and the number of second fitting teeth 177B are the same. Therefore, during normal driving, the rotational driving force of the input shaft can be reliably transmitted to the output shaft 15, and when back torque occurs, the engine brake can be reliably applied.

[0078] In the clutch device 10 of this embodiment, when the pressure plate 170 is divided into a first region T11 and a second region T12 by a straight line SL7 passing through the axis CL1, the number of first mating teeth 177A and the number of second mating teeth 177B are different in the first region T11 and the second region T12. That is, the number of second mating teeth 177B is reduced in the first region T11, and the number of first mating teeth 177A is reduced in the second region T12. As a result, the pressure plate 170 can be made lighter.

[0079] Figure 18 is a diagram corresponding to Figure 17 relating to a modified example. The clutch device 10 relating to the modified example is equipped with a pressure plate 370 instead of the pressure plate 170 (see Figure 17) of the second embodiment. The pressure plate 370 is the same as the pressure plate 170 except that the number of pressure plate teeth 177 is different. The pressure plate 370 has 16 pressure plate teeth 177. The pressure plate teeth 177 have 7 first mating teeth 177A and 8 second mating teeth 177B.

[0080] In the modified clutch device 10, the number of second mating teeth 177B is greater than the number of first mating teeth 177A. Compared to the case where the number of first mating teeth 177A and the number of second mating teeth 177B are the same, the number of first mating teeth 177A is smaller. In this case, depending on the characteristics of the vehicle on which the clutch device 10 is installed, it may be desirable to increase the rotational driving force transmitted from the input shaft to the output shaft 15 (see Figure 1). In order to reduce the weight of the pressure plate 170 (see Figure 17) by reducing the number of pressure plate teeth 177 (see Figure 17) in the second embodiment, the pressure plate 370 has the same number of second mating teeth 177B as the pressure plate 170, but with a reduced number of first mating teeth 177A. Therefore, it is possible to increase the rotational driving force transmitted from the input shaft to the output shaft 15 (see Figure 1) while reducing the weight of the pressure plate 370.

[0081] In the modified clutch device 10, the clutch center 140 rotates in the first circumferential direction S1. This makes it possible to increase the rotational driving force transmitted from the input shaft to the output shaft 15 (see Figure 1) during normal driving.

[0082] <Third Embodiment> In the first embodiment described above, the pressure plate 70 (see Figure 9A) had a boss portion 84 and the clutch center 40 (see Figure 5) had a spring holder 54 (see Figure 5), but the embodiment is not limited to these. Figure 19 shows the clutch center 240 and pressure plate 270 assembled according to the third embodiment, and is a view from the left L. In the third embodiment, the clutch center 240 is located to the left L (towards the front in Figure 19) of the pressure plate 270. In this embodiment, the clutch center 240 has a boss portion 284. The boss portion 284 extends from the left L to the right R (towards the back in Figure 19). In this embodiment, the first axial direction corresponds to the left L, and the second axial direction corresponds to the right R.

[0083] The pressure plate 270 has a disc portion 244 into which a fitting hole 80 into which the output shaft holding portion 50 of the clutch center 240 is inserted, an outer cylindrical portion 245 connected to the disc portion 244, and an annular flange 298 located radially Q outward from the outer cylindrical portion 245. The pressure plate 270, together with the clutch center 240, clamps the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 1). The flange 298 is configured to press against the input side rotating plate 20 and the output side rotating plate 22.

[0084] The disc portion 244 has a plurality (3 in this embodiment) of first through holes 244a and a plurality (3 in this embodiment) of second through holes 244b. The first through holes 244a and the second through holes 244b penetrate the disc portion 244 in the axial direction D (see Figure 1). The first through holes 244a and the second through holes 244b are arranged at equal intervals with respect to the circumferential direction S, similar to the first through hole 44a (see Figure 5) and the second through hole 44b (see Figure 5) in the first embodiment. The position of the center 244C1 of the first through hole 244a in the radial direction Q is approximately the same as the position of the center 284E of the boss portion 284 in the radial direction Q. The diameter of the first through hole 244a is slightly larger than the diameter of the boss portion 284. The diameter of the second through hole 244b is approximately the same as the diameter of the first through hole 244a. A virtual circle CR7, centered on axis CL1 and passing through the innermost end 284N in the radial direction Q of the boss portion 284, is located radially outside Q than a virtual circle CR6, which passes through the innermost end 244aN of the first through hole 244a. The innermost end 244bN in the radial direction Q of the second through hole 244b is located radially outside Q than a virtual circle CR7, centered on axis CL1 and passing through the innermost end 284N of the radial direction Q of the boss portion 284. Therefore, even if the position of the boss portion 284 in the circumferential direction S and the position of the second through hole 244b in the circumferential direction S are aligned, the boss portion 284 cannot penetrate the second through hole 244b in the axial direction D, and the pressure plate 270 and the clutch center 240 cannot be assembled. In this embodiment, the pressure spring 25 abuts against the disc portion 244 of the pressure plate 270. In Figure 19, the pressure spring 25 is illustrated by a dashed line.

[0085] The pressure plate 270 is equipped with a plurality of (3 in this embodiment) spring holders 254. The spring holders 254 extend inward from the outer cylindrical portion 245 in the radial direction Q. The plurality of spring holders 254 are arranged at equal intervals in the circumferential direction S, similar to the spring holder 54 of the first embodiment (see Figure 5). The pressure spring 25 is positioned inside the spring holder 254 in the radial direction Q. The spring holder 254 is a member that suppresses displacement of the pressure spring 25 in the radial direction Q and the circumferential direction S. Reference numeral L16 represents the length of the spring holder 254 in the radial direction Q. The length L16 is the longest length in the radial direction Q of the spring holder 254. The length L16 is less than or equal to the radius R1 of the outer shape of the pressure spring 25 (see Figure 5).

[0086] The spring holder 254 has a support surface 254A facing the pressure spring 25 in the radial direction Q, a first support side surface 254B connected to the end of the support surface 254A on the first circumferential direction S1 side, and a second support side surface 254C connected to the end of the support surface 254A on the second circumferential direction S2 side. The support surface 254A, the first support side surface 254B, and the second support side surface 254C are the same as the support surface 54A (see Figure 5), the first support side surface 54B (see Figure 5), and the second support side surface 54C (see Figure 5) according to the first embodiment, except that they are provided on the outer cylindrical portion 245 of the pressure plate 270.

[0087] The outer cylinder portion 245 is provided with a plurality (3 in this embodiment) of oil discharge holes 245F that penetrate in the radial direction Q. The oil discharge holes 245F are the same as the oil discharge holes 45F (see Figure 5) in the first embodiment, except that they are formed in the outer cylinder portion 245 of the pressure plate 270. The oil discharge holes 245F are positioned such that the distance between the spring holder 254 and the oil discharge holes 245F in the circumferential direction S is less than or equal to the length L16 of the radial direction Q of the spring holder 254, or they overlap the end 254S of the spring holder 254 on the first circumferential direction S1 side in the circumferential direction S. When the pressure plate 270 rotates in the first circumferential direction S1, the flow of oil is blocked by the first support side surface 254B of the spring holder 254. Since the circumferential distance S between the spring holder 254 and the oil discharge hole 245F is less than or equal to the radial length Q of the spring holder 254 L16, at least a portion of the oil blocked by the first support side surface 254B is smoothly discharged to the outside of the pressure plate 270 through the oil discharge hole 245F. This ensures a reliable supply of oil to the input side rotating plate 20 (see Figure 1) and the output side rotating plate 22 (see Figure 2). Although detailed illustrations are omitted, the three oil discharge holes 245F are located at different positions in the axial direction D. Therefore, as in the first embodiment, oil can be reliably supplied to the input side rotating plate 20 and the output side rotating plate 22, which are located at different positions in the axial direction D. The three oil discharge holes 245F are located at at least partially the same position with respect to the axial direction D as the output side rotating plates 22N, 22M, and 22L (see Figure 7). This ensures a reliable supply of oil to all output side rotating plates 22, as in the first embodiment.

[0088] <Fourth Embodiment> Figure 20 is a cross-sectional view of a clutch device 410 according to the fourth embodiment. As shown in Figure 20, the clutch device 410 includes an output shaft 15, a plurality of input-side rotating plates 20, a plurality of output-side rotating plates 22, a pressure spring 25, a clutch housing 30, a clutch center 440, a pressure plate 470, and a support plate 100.

[0089] As shown in Figure 20, the clutch center 440 is housed in the clutch housing 30. The clutch center 440 is positioned concentrically with the clutch housing 30. As shown in Figure 21, the clutch center 440 has an output shaft holding portion 50 held on the output shaft 15 (see Figure 20), an outer cylinder portion 45 located radially Q outward from the output shaft holding portion 50, a disc portion 44 connected to the output shaft holding portion 50 and the outer cylinder portion 45, and an annular flange 68 located radially Q outward from the outer cylinder portion 45. The clutch center 440 holds an input side rotating plate 20 and a plurality of output side rotating plates 22 arranged alternately in the axial direction D. In this embodiment, the clutch center 440 holds all of the output side rotating plates 22. The clutch center 440 rotates together with the output shaft 15.

[0090] As shown in Figure 21, the disc portion 44 has a plurality (4 in this embodiment) of through holes 444a and a plurality (4 in this embodiment) of recesses 456. The through holes 444a penetrate the disc portion 44 in the axial direction D. The shape of the through holes 444a is a perfect circle when viewed from the axial direction D. As will be described later, the pressure plate 470 (see Figure 24) has a boss portion 484 (see Figures 24 and 25). The position of the center 444C1 of the through hole 444a in the radial direction Q is approximately the same as the position of the center 484E of the boss portion 484 (see Figure 25) in the radial direction Q. The diameter of the through hole 444a is slightly larger than the diameter of the boss portion 484.

[0091] As shown in Figure 21, the recess 456 is formed to recess from left L to right R. The recess 456 does not penetrate the disc portion 44 in the axial direction D. The shape of the recess 456 is rectangular when viewed from the axial direction D. The stopper portion 496 (see Figure 24), which will be described later, of the pressure plate 470 engages with the recess 456. The through hole 444a and the recess 456 are arranged at equal intervals with respect to the circumferential direction S. The through hole 444a and the recess 456 are arranged alternately in the circumferential direction S. When viewed from the axial direction D of the output shaft 15, at least a portion of the second spline groove 48B faces the outer wall 456W of the recess 456 in the radial direction Q. When viewed from the axial direction D of the output shaft 15, at least a portion of the third spline groove 48C faces the outer wall 456W of the recess 456 in the radial direction Q. In this embodiment, when viewed in the axial direction D of the output shaft 15, the first spline groove 48A does not face the outer wall 456W of the recess 456 in the radial direction Q, but it may face it. The wall 456W is a wall that extends in the circumferential direction S and the axial direction D.

[0092] As shown in Figures 21 and 22, the multiple (17 in this embodiment) clutch center teeth 47 are arranged in the circumferential direction S. The multiple clutch center teeth 47 are formed at non-uniform positions with respect to the circumferential direction S. As shown in Figure 23, the number of clutch center teeth 47 (17 in this embodiment) is less than the number of rotating plate teeth 22b of the output side rotating plate 22 (34 in this embodiment). The number of clutch center teeth 47 is, for example, less than half the number of rotating plate teeth 22b.

[0093] As shown in Figures 22 and 23, the multiple spline grooves 48 are arranged in the circumferential direction S. The multiple spline grooves 48 include a first spline groove 48A with a first length LS1 in the circumferential direction S, a second spline groove 48B with a second length LS2 that is longer than the first length LS1 in the circumferential direction S, and a third spline groove 48C with a third length LS3 that is longer than the second length LS2 in the circumferential direction S. In this embodiment, the multiple spline grooves 48 include two first spline grooves 48A, thirteen second spline grooves 48B, and two third spline grooves 48C, but the number of first spline grooves 48A, second spline grooves 48B, and third spline grooves 48C is not limited thereto. In this embodiment, the proportion of first spline grooves 48A among the multiple spline grooves 48 is less than 20%. In this embodiment, of the 17 spline grooves 48, there are two first spline grooves 48A, and the proportion of first spline grooves 48A among the multiple spline grooves 48 is approximately 1.2%. With respect to the circumferential direction S, the first spline grooves 48A and the third spline grooves 48C are arranged adjacent to each other. More specifically, with respect to the circumferential direction S, the first spline grooves 48A and the third spline grooves 48C are arranged adjacent to each other with the clutch center teeth 47 in between. With respect to the circumferential direction S, there is no second spline groove 48B between the first spline grooves 48A and the third spline grooves 48C. However, the number and arrangement of the first spline grooves 48A, the second spline grooves 48B and the third spline grooves 48C are not limited to this.

[0094] As shown in Figure 22, when viewed in the axial direction D of the output shaft 15, there exists a straight line LC that passes through the center 440C of the clutch center 440, bisects the clutch center 440 into a first region CT1 and a second region CT2, and in the first region CT1 and the second region CT2, the multiple clutch center teeth 47 and the multiple spline grooves 48 are not symmetrical with respect to the straight line LC. When the clutch center 440 is bisected into a first region CT1 and a second region CT2 by the straight line LC passing through the center 440C of the clutch center 440 when viewed in the axial direction D of the output shaft 15, the multiple clutch center teeth 47 and the multiple spline grooves 48 in the first region CT1 and the second region CT2 are not symmetrical with respect to the straight line LC. For example, in the example shown in Figure 22, the straight line LC passes through the second spline groove 48B and the third spline groove 48C, the number of clutch center teeth 47 in the first region CT1 is 9, and the number of clutch center teeth 47 in the second region CT2 is 8.

[0095] As shown in Figure 20, the pressure plate 470 is housed in the clutch housing 30. The pressure plate 470 is located between the clutch housing 30 and the clutch center 440. The pressure plate 470 is provided so as to be able to move toward and away from the clutch center 440. The pressure plate 470 is provided so as to be able to rotate relative to the clutch center 440. The pressure plate 470 is configured to be able to press against the input side rotating plate 20 and the output side rotating plate 22. The pressure plate 470 is positioned concentrically with the clutch center 440 and the clutch housing 30. As shown in Figure 24, the pressure plate 470 has a pressure plate body 72 and a flange 98. The pressure plate 470 does not hold the output side rotating plate 22 (see Figure 20).

[0096] As shown in Figures 24 and 25, the pressure plate 470 has a plurality of (four in this embodiment) boss portions 484. The plurality of boss portions 484 are arranged at equal intervals in the circumferential direction S. The boss portions 484 are formed in a cylindrical shape. The boss portions 484 are located radially Q outward from the fitting hole 80. The boss portions 484 extend to the right R from the pressure plate body 72. In this embodiment, as shown in Figure 20, the boss portions 484 extend to the right R from the flange 68 of the clutch center 440. The boss portions 484 have fastening holes 84H into which bolts 28 are inserted. When the pressure plate 470 and the clutch center 440 are assembled coaxially, the boss portions 484 are positioned inside the through hole 444a of the clutch center 440 and penetrate the through hole 444a in the axial direction D.

[0097] As shown in Figure 24, the pressure plate 470 is equipped with a plurality (four in this embodiment) of stopper portions 496. The stopper portions 496 are formed on the pressure plate body 72. The stopper portions 496 protrude to the right R from the pressure plate body 72. The stopper portions 496 are located between adjacent boss portions 484 with respect to the circumferential direction S. The plurality of stopper portions 496 are arranged at equal intervals in the circumferential direction S. When the pressure plate 470 and the clutch center 440 are assembled coaxially, the stopper portions 496 engage with the recesses 456 of the clutch center 440, thereby restricting the relative rotation between the pressure plate 470 and the clutch center 440.

[0098] As described above, according to the clutch device 410 of this embodiment, the plurality of spline grooves 48 include a first spline groove 48A whose length in the circumferential direction S is a first length LS1, and a second spline groove 48B whose length in the circumferential direction S is a second length LS2 which is longer than the first length LS1. When viewed in the axial direction D of the output shaft 15, if the clutch center 440 is divided into a first region CT1 and a second region CT2 by a straight line LC passing through the center 440C of the clutch center 440, the plurality of clutch center teeth 47 and the plurality of spline grooves 48 are not symmetrical with respect to the straight line LC in the first region CT1 and the second region CT2. That is, the clutch center teeth 47 are not arranged at equal intervals in the circumferential direction S, and the number of clutch center teeth 47 is less than when they are arranged at equal intervals. As a result, the clutch center 440 can be made lighter.

[0099] In the clutch device 410 of this embodiment, the plurality of spline grooves 48 further include a third spline groove 48C having a third length LS3 whose length in the circumferential direction S is longer than the second length LS2, and the first spline groove 48A and the third spline groove 48C are arranged adjacent to each other with respect to the circumferential direction S. According to the above embodiment, the output side rotating plate 22 can be held more securely by the clutch center teeth 47.

[0100] In the clutch device 410 of this embodiment, the proportion of the first spline groove 48A among the multiple spline grooves 48 is less than 20%. According to the above embodiment, the number of clutch center teeth 47 can be reduced, and therefore the clutch center 440 can be made lighter.

[0101] In the clutch device 410 of this embodiment, the number of clutch center teeth 47 is less than the number of multiple rotating plate teeth 22b arranged in the circumferential direction S, which are formed to protrude inward in the radial direction Q from the rotating plate body 22a of the output side rotating plate 22. According to the above embodiment, the clutch center 440 can be made lighter.

[0102] Figure 26 is a plan view of a modified pressure plate 570. The modified clutch device 410 is equipped with a pressure plate 570 in place of the pressure plate 470 of the fourth embodiment (see Figure 25). The pressure plate 570 is the same as the pressure plate 470 except that it is equipped with pressure plate teeth 77. As shown in Figure 26, when viewed in the axial direction D of the output shaft 15, there exists a pressure plate line LP that passes through the center 70C of the pressure plate 570, bisects the pressure plate 570 into a first pressure plate region PT1 and a second pressure plate region PT2, and in the first pressure plate region PT1 and the second pressure plate region PT2, the plurality of pressure plate teeth 77 and the plurality of inter-tooth portions 72P are not symmetrical. When viewed in the axial direction D of the output shaft 15, if the pressure plate 570 is divided into a first pressure plate region PT1 and a second pressure plate region PT2 by a pressure plate line LP passing through the center 70C of the pressure plate 570, then the multiple pressure plate teeth 77 and multiple intertooth portions 72P in the first pressure plate region PT1 and the second pressure plate region PT2 are not symmetrical with respect to the pressure plate line LP. For example, in the example shown in Figure 26, the pressure plate line LP passes through the third intertooth portion 72P3, the number of pressure plate teeth 77 in the first pressure plate region PT1 is 6, and the number of pressure plate teeth 77 in the second pressure plate region PT2 is 4.

[0103] In the modified clutch device 410, when viewed in the axial direction D of the output shaft 15, if the pressure plate 570 is divided into a first pressure plate region PT1 and a second pressure plate region PT2 by a pressure plate line LP passing through the center 70C of the pressure plate 570, the multiple pressure plate teeth 77 and the multiple inter-tooth portions 72P in the first pressure plate region PT1 and the second pressure plate region PT2 are not symmetrical with respect to the pressure plate line LP. That is, the pressure plate teeth 77 are not arranged at equal intervals in the circumferential direction S, and the number of pressure plate teeth 77 is less than when they are arranged at equal intervals. As a result, the pressure plate 570 can be made lighter.

[0104] Preferred embodiments of the present invention have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms.

[0105] The technology disclosed herein can be applied to various types of clutch devices. In the embodiments described above, as shown in Figure 1, a so-called external-cutting type clutch device is described as an example, in which the pressure plate 70 is located between the bottom wall 31 of the clutch housing 30 and the clutch center 40 in the axial direction D, but the invention is not limited thereto. For example, the invention can also be similarly applied to a so-called internal-cutting type clutch device in which, in the axial direction D, the pressure plate 70 is located on the opposite side of the clutch center 40 from the bottom wall 31 of the clutch housing 30. Furthermore, in the first to third embodiments described above, the first axial end (right R side) 77R of the pressure plate teeth 77 is located on the first axial side than the second axial end 20La of the first input side rotating plate 20L, which is located furthest to the second axial side (left L side) among the plurality of input side rotating plates 20, and is located on the second axial side than the second axial end 22La of the first output side rotating plate 22L, which is located furthest to the second axial side among the plurality of output side rotating plates 22, but is not limited to this. For example, the first axial end 77R of the pressure plate teeth 77 may be located on the first axial side than the first output side rotating plate 22L.

[0106] In the first embodiment described above, the proportion of the first spline groove 48A among the multiple spline grooves 48 is approximately 67%, but it is not limited to this. The proportion of the first spline groove 48A among the multiple spline grooves 48 may be less than 20%.

[0107] In each of the embodiments described above, the intertooth portion 72P is formed between adjacent pressure plate teeth 77 and penetrates in the radial direction Q, but is not limited to this. For example, an outer peripheral wall may be formed on the inside of the pressure plate teeth 77 in the radial direction Q, extending to the right R from the pressure plate body 72 and continuous in the circumferential direction S, and the pressure plate teeth 77 may be formed so as to protrude outward from this outer peripheral wall in the radial direction Q. In this case, when viewed from the radial direction Q, the intertooth portion, i.e., the space between adjacent pressure plate teeth 77, does not penetrate in the radial direction Q but is closed by the outer peripheral wall.

[0108] In the fourth embodiment described above, the pressure plate 470 was configured not to hold the output-side rotating plate 22, but the pressure plate 470 may be configured to hold the output-side rotating plate 22. That is, the clutch center 440 may hold a part of the output-side rotating plate 22, and the pressure plate 470 may hold the other part of the output-side rotating plate 22.

[0109] Item 1: A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a plurality of input-side rotating plates arranged in a first axial direction which is the direction of the axis of the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the first axial direction; a clutch center that rotates together with the output shaft; and a pressure plate provided so as to be approachable by moving in the first axial direction relative to the clutch center and so as to be separated by moving in a second axial direction which is opposite to the first axial direction relative to the clutch center, and pressing the input-side rotating plates and the output-side rotating plates, wherein the plurality of input-side rotating plates include a first input-side rotating plate located furthest toward the second axial direction among the plurality of input-side rotating plates; the plurality of output-side rotating plates include a first output-side rotating plate located furthest toward the second axial direction among the plurality of output-side rotating plates; and the pressure plate comprises a pressure plate body, A clutch device comprising: a flange located radially outward from the output shaft than the pressure plate body and facing the first input side rotating plate; a plurality of pressure plate teeth extending in the first axial direction and arranged in the circumferential direction of the output shaft; the output side rotating plate comprising: an annular rotating plate body; a plurality of rotating plate teeth projecting radially inward from the rotating plate body and arranged in the circumferential direction; the first axial end of the pressure plate teeth being located on the first axial side of the second axial end of the first input side rotating plate, and on the second axial side of the second axial end of the first output side rotating plate; and the number of pressure plate teeth being less than the number of rotating plate teeth.

[0110] Item 2: The clutch device according to Item 1, wherein the plurality of rotating plate teeth of the output side rotating plate are provided at predetermined intervals in the circumferential direction, the pressure plate teeth are provided on the pressure plate body, the pressure plate body has a connecting surface located radially inward from the pressure plate teeth, and a missing tooth surface located radially outward from the connecting surface and between adjacent pressure plate teeth in the circumferential direction, with a circumferential length longer than the predetermined interval, and the missing tooth surface and the connecting surface are formed substantially flush.

[0111] Item 3: The clutch device according to Item 1, wherein the clutch center comprises an output shaft holding portion held on the output shaft, an outer cylindrical portion located radially outward from the output shaft holding portion, and a plurality of clutch center teeth protruding radially outward from the outer cylindrical portion and arranged in the circumferential direction, the output side rotating plate being held on the clutch center teeth, and at least one of the plurality of pressure plate teeth being configured to mesh with the clutch center teeth in the circumferential direction.

[0112] Item 4: The clutch device according to Item 3, wherein the plurality of rotating plate teeth of the output side rotating plate are arranged at predetermined intervals in the circumferential direction, the outer cylinder portion of the clutch center has a gap groove formed between adjacent clutch center teeth in the circumferential direction, the circumferential length of which is longer than the predetermined interval, the plurality of clutch center teeth have a first side surface located on one side in the circumferential direction and connected to the outer cylinder portion, and a second side surface located on the other side in the circumferential direction and connected to the outer cylinder portion, and the plurality of pressure plate teeth have a first fitting tooth that abuts against the first side surface and a second fitting tooth that abuts against the second side surface.

[0113] Item 5: The clutch device according to item 4, wherein the number of first mating teeth and the number of second mating teeth are the same.

[0114] Item 6: The clutch device according to item 4, wherein the number of the second mating teeth is greater than the number of the first mating teeth.

[0115] Item 7: The clutch device according to item 6, wherein the clutch center rotates from the other side in the circumferential direction to the one side.

[0116] Item 8: The clutch device according to Item 4, wherein, when the pressure plate is viewed in the axial direction, and the pressure plate is divided into a first region and a second region by a straight line passing through the center of the output shaft, the number of first mating teeth and the number of second mating teeth are different in at least one of the first region and the second region.

[0117] Item 9: The clutch device according to Item 1, wherein the plurality of rotating plate teeth of the output side rotating plate are provided at predetermined intervals in the circumferential direction, the pressure plate teeth are provided on the pressure plate body, the pressure plate body has a plurality of missing tooth surfaces located between adjacent pressure plate teeth in the circumferential direction, the circumferential length of which is longer than the predetermined interval, and the sum of the circumferential lengths of the plurality of missing tooth surfaces is longer than the sum of the circumferential lengths of the plurality of pressure plate teeth.

[0118] Item 10: The clutch device according to item 9, wherein the sum of the circumferential lengths of the plurality of missing tooth surfaces is 2.5 times or more and 10 times or less the sum of the circumferential lengths of the plurality of pressure plate teeth.

[0119] Item 11: The clutch device according to Item 1, further comprising a support plate fixed to either the pressure plate or the clutch center, wherein one of the pressure plate or the clutch center has a boss portion extending toward the other of the pressure plate or the clutch center and having fastening holes formed therein for attaching the support plate, the plurality of rotating plate teeth of the output side rotating plate are provided at predetermined intervals in the circumferential direction, the pressure plate teeth are provided on the pressure plate body, the pressure plate body has a plurality of missing tooth surfaces located between adjacent pressure plate teeth in the circumferential direction and having a circumferential length longer than the predetermined interval, and when the pressure plate is viewed in the axial direction, at least a portion of the missing tooth surfaces is located between a straight line passing through the center of the output shaft and one end of the boss portion in the circumferential direction and a straight line passing through the center of the output shaft and the other end of the boss portion in the circumferential direction.

[0120] Item 12: The clutch device according to Item 11, wherein, when the pressure plate is viewed in the axial direction, the straight line passing through the center of the output shaft and the center of the boss portion passes through the toothless surface.

[0121] Item 13: The clutch device according to Item 1, wherein the plurality of pressure plate teeth include first pressure plate teeth aligned with adjacent circumferential pressure plate teeth at a first pitch, and second pressure plate teeth aligned with adjacent circumferential pressure plate teeth at a second pitch longer than the first pitch.

[0122] Item 14: The clutch device according to item 13, wherein the plurality of pressure plate teeth include a third pressure plate tooth that is aligned with the circumferentially adjacent pressure plate tooth at a third pitch longer than the second pitch.

[0123] Item 15: The clutch device according to item 13, wherein the clutch center comprises an output shaft holding portion held on the output shaft, an outer cylinder portion located radially outward from the output shaft holding portion, and a plurality of clutch center teeth protruding radially outward from the outer cylinder portion and arranged in the circumferential direction, the output side rotating plate being held on the clutch center teeth, and the outer cylinder portion having a plurality of spline grooves formed between adjacent clutch center teeth, the plurality of spline grooves comprising a first spline groove having a first length in the circumferential direction and a second spline groove having a second length in the circumferential direction that is longer than the first length.

[0124] Item 16: The clutch device according to item 15, wherein the plurality of spline grooves have a third spline groove having a third length whose circumferential length is longer than the second length.

[0125] Item 17: The clutch device according to item 15, wherein the axial length of the clutch center teeth is longer than the axial length of the pressure plate teeth.

[0126] Item 18: The clutch device according to Item 1, wherein the pressure plate teeth are provided on the pressure plate body, and the pressure plate body has a first intertotal surface located between adjacent pressure plate teeth in the circumferential direction and having a first circumferential length, and a second intertotal surface located between adjacent pressure plate teeth in the circumferential direction and having a second circumferential length longer than the first circumferential length.

[0127] Item 19: The clutch device according to item 18, wherein the pressure plate body has a third intertooth surface located between adjacent pressure plate teeth in the circumferential direction, the third intertooth surface having a circumferential length longer than the second circumferential length.

[0128] Item 20: The clutch device according to item 18, wherein the clutch center comprises an output shaft holding portion held on the output shaft, an outer cylinder portion located radially outward from the output shaft holding portion, and a plurality of clutch center teeth protruding radially outward from the outer cylinder portion and arranged in the circumferential direction, the output side rotating plate being held on the clutch center teeth, and the outer cylinder portion having a plurality of spline grooves formed between adjacent clutch center teeth, the plurality of spline grooves comprising a first spline groove having a first length in the circumferential direction and a second spline groove having a second length in the circumferential direction that is longer than the first length.

[0129] Item 21: The clutch device according to item 20, wherein the plurality of spline grooves have a third spline groove having a third length whose circumferential length is longer than the second length.

[0130] Item 22: The clutch device according to item 20, wherein the axial length of the clutch center teeth is longer than the axial length of the pressure plate teeth.

[0131] Item 23: The clutch device according to Item 1, wherein the plurality of rotating plate teeth of the output side rotating plate are provided at predetermined intervals in the circumferential direction, the pressure plate teeth are provided on the pressure plate body, the pressure plate body has first to fourth missing tooth surfaces located between adjacent pressure plate teeth in the circumferential direction and having a circumferential length longer than the predetermined interval, and when the pressure plate is viewed in the axial direction, the pressure plate is divided into first to fourth regions by a first straight line passing through the center of the output shaft and a second straight line passing through the center of the output shaft and perpendicular to the first straight line, and each of the first to fourth regions includes at least a portion of the first to fourth missing tooth surfaces.

[0132] Item 24: A clutch device for transmitting or interrupting the rotational driving force of an input shaft to an output shaft, comprising: a plurality of input-side rotating plates arranged in a first axial direction which is the direction of the axis of the output shaft; a plurality of output-side rotating plates arranged alternately with the input-side rotating plates in the first axial direction; a clutch center that rotates together with the output shaft; and a pressure plate provided so as to be approachable by moving in the first axial direction relative to the clutch center and so as to be separated by moving in a second axial direction which is opposite to the first axial direction relative to the clutch center, and pressing the input-side rotating plates and the output-side rotating plates, wherein the plurality of input-side rotating plates include a first input-side rotating plate located furthest toward the second axial direction among the plurality of input-side rotating plates; the plurality of output-side rotating plates include a first output-side rotating plate located furthest toward the second axial direction among the plurality of output-side rotating plates; and the pressure plate comprises a pressure plate body, A clutch device comprising: a flange located radially outward from the output shaft than the pressure plate body and facing the first input side rotating plate; and a plurality of pressure plate teeth extending in the first axial direction and arranged in the circumferential direction of the output shaft, wherein the pressure plate body has a first intertooth surface located between adjacent pressure plate teeth in the circumferential direction and having a first circumferential length; and a second intertooth surface located between adjacent pressure plate teeth in the circumferential direction and having a second circumferential length longer than the first circumferential length.

[0133] Item 25: The clutch device according to item 24, wherein the pressure plate body has a third intertooth surface located between adjacent pressure plate teeth in the circumferential direction, the third circumferential length being longer than the second circumferential length.

[0134] Item 26: The clutch device according to item 24, wherein the first axial end of the pressure plate teeth is located on the first axial side of the second axial end of the first input side rotating plate and on the second axial side of the second axial end of the first output side rotating plate.

[0135] 10 Clutch device 15 Output shaft 20 Input side rotating plate 22 Output side rotating plate 30 Clutch housing 40 Clutch center 45 Outer cylinder part 47 Clutch center teeth 48 Spline groove 48A First spline groove 48B Second spline groove 48C Third spline groove 50 Output shaft holding part 70 Pressure plate

Claims

1. A clutch device for transmitting or interrupting the rotational driving force of an input shaft, which is rotationally driven by the driving force of a drive source, 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 driving of the input shaft, and which rotates together with the output shaft; and a pressure plate provided so as to be able to approach and move away from the clutch center, and which can press the input-side rotating plates and a plurality of output-side rotating plates arranged alternately with the input-side rotating plates, wherein the clutch center comprises: an output shaft holding portion to which the output shaft is connected; an outer cylinder portion located radially outward from the output shaft holding portion; a plurality of clutch center teeth that hold the output-side rotating plates and protrude radially outward from the outer cylinder portion and are arranged in the circumferential direction; and a plurality of spline grooves formed between adjacent clutch center teeth, wherein the plurality of spline grooves include a first spline groove whose circumferential length is a first length and a second spline groove whose circumferential length is a second length longer than the first length. A clutch device in which, when viewed in the axial direction of the output shaft, the clutch center is divided into a first region and a second region by a straight line passing through the center of the clutch center, the plurality of clutch center teeth and the plurality of spline grooves are not symmetrical with respect to the straight line in the first region and the second region.

2. The clutch device according to claim 1, wherein the plurality of spline grooves further include a third spline groove having a third length whose circumferential length is longer than the second length, and the first spline groove and the third spline groove are arranged adjacent to each other in the circumferential direction.

3. The clutch device according to claim 1 or 2, wherein the proportion of the first spline groove among the plurality of spline grooves is less than 20%.

4. The clutch device according to claim 1, wherein the number of clutch center teeth is less than the number of circumferentially arranged rotating plate teeth formed to protrude radially inward from the rotating plate body of the output side rotating plate.

5. The output-side rotating plate has an annular rotating plate body and a plurality of rotating plate teeth that protrude radially inward from the rotating plate body and are arranged in the circumferential direction, and the plurality of rotating plate teeth of the output-side rotating plate are provided at predetermined intervals in the circumferential direction, and the pressure plate has a pressure plate body and a flange that is located radially outward from the pressure plate body and extends radially outward, a plurality of pressure plate teeth that extend in the axial direction of the output shaft and are arranged in the circumferential direction, and a plurality of intertooth portions formed between adjacent pressure plate teeth, and the plurality of intertooth portions include a first intertooth portion whose circumferential length is a first intertooth length and a second intertooth portion whose circumferential length is a second intertooth length which is longer than the first intertooth length, The clutch device according to claim 1, wherein, when viewed in the axial direction of the output shaft, the pressure plate is divided into a first pressure plate region and a second pressure plate region by a pressure plate line passing through the center of the pressure plate, and the plurality of pressure plate teeth and the plurality of inter-tooth portions in the first pressure plate region and the second pressure plate region are not symmetrical with respect to the pressure plate line.

6. A clutch device for transmitting or interrupting the rotational driving force of an input shaft, which is rotationally driven by the driving force of a drive source, to an output shaft, comprising: a clutch center housed in a clutch housing that holds a plurality of input-side rotating plates that are rotationally driven by the rotational drive of the input shaft, and which is rotationally driven together with the output shaft; and a pressure plate provided so as to be able to approach and move away from the clutch center, and which is capable of pressing the input-side rotating plates and a plurality of output-side rotating plates arranged alternately with the input-side rotating plates, wherein the output-side rotating plates have an annular rotating plate body and a plurality of rotating plate teeth that protrude radially inward from the rotating plate body and are arranged in the circumferential direction, the plurality of rotating plate teeth of the output-side rotating plates are provided at predetermined intervals in the circumferential direction, and the pressure plate has a pressure plate body, a flange located radially outward from the pressure plate body and extending radially outward, and a plurality of pressure plate teeth that extend in the axial direction of the output shaft and are arranged in the circumferential direction, A clutch device having a plurality of intertooth portions formed between adjacent pressure plate teeth, wherein the plurality of intertooth portions include a first intertooth portion whose circumferential length is a first intertooth length and a second intertooth portion whose circumferential length is a second intertooth length longer than the first intertooth length, and when the pressure plate is divided into a first pressure plate region and a second pressure plate region by a pressure plate line passing through the center of the pressure plate when viewed in the axial direction of the output shaft, the plurality of pressure plate teeth and the plurality of intertooth portions in the first pressure plate region and the second pressure plate region are not symmetrical with respect to the pressure plate line.

7. The clutch device according to claim 6, wherein the intertooth portion includes a plurality of missing tooth portions whose circumferential length is longer than the predetermined interval, and the sum of the circumferential lengths of the plurality of missing tooth portions is longer than the sum of the circumferential lengths of the plurality of pressure plate teeth.

8. The clutch device according to claim 7, wherein the sum of the circumferential lengths of the plurality of missing teeth is 2.5 times or more and 10 times or less the sum of the circumferential lengths of the plurality of pressure plate teeth.

9. The clutch device according to claim 6, further comprising a support plate fixed to either the pressure plate or the clutch center, wherein one of the pressure plate or the clutch center has a boss portion extending toward the other of the pressure plate or the clutch center and having fastening holes formed therein for attaching the support plate, the intertooth portion includes a plurality of missing teeth portions whose circumferential length is longer than the predetermined interval, and when the pressure plate is viewed in the axial direction, at least a portion of the missing teeth is located between a straight line passing through the center of the output shaft and one circumferential end of the boss portion and a straight line passing through the center of the output shaft and the other circumferential end of the boss portion.

10. The clutch device according to claim 9, wherein, when the pressure plate is viewed in the axial direction, a straight line passing through the center of the output shaft and the center of the boss portion passes through the missing tooth portion.

11. The clutch device according to claim 6, wherein the plurality of pressure plate teeth include first pressure plate teeth aligned with adjacent circumferential pressure plate teeth at a first pitch, and second pressure plate teeth aligned with adjacent circumferential pressure plate teeth at a second pitch longer than the first pitch.

12. The clutch device according to claim 11, wherein the plurality of pressure plate teeth include third pressure plate teeth that are aligned with adjacent pressure plate teeth in the circumferential direction at a third pitch longer than the second pitch.

13. The clutch device according to claim 6, wherein the clutch center comprises an output shaft holding portion held on the output shaft, an outer cylinder portion located radially outward from the output shaft holding portion, and a plurality of clutch center teeth protruding radially outward from the outer cylinder portion and arranged in the circumferential direction, at least one of the output side rotating plates is held on the clutch center teeth, and a plurality of spline grooves are formed in the outer cylinder portion between adjacent clutch center teeth, and the plurality of spline grooves comprises a first spline groove having a first length in the circumferential direction and a second spline groove having a second length in the circumferential direction that is longer than the first length.

14. The clutch device according to claim 13, wherein the plurality of spline grooves have a third spline groove having a third length whose circumferential length is longer than the second length.

15. The clutch device according to claim 13, wherein the axial length of the clutch center teeth is longer than the axial length of the pressure plate teeth.

16. The clutch device according to claim 6, wherein the pressure plate teeth are provided on the pressure plate body, and the pressure plate body has a first intertotal surface located between adjacent pressure plate teeth in the circumferential direction and having a first circumferential length, and a second intertotal surface located between adjacent pressure plate teeth in the circumferential direction and having a second circumferential length longer than the first circumferential length.

17. The clutch device according to claim 16, wherein the pressure plate body has a third intertooth surface located between adjacent pressure plate teeth in the circumferential direction, the third intertooth surface having a circumferential length longer than the second circumferential length.

18. The clutch device according to claim 16, wherein the clutch center comprises an output shaft holding portion held on the output shaft, an outer cylinder portion located radially outward from the output shaft holding portion, and a plurality of clutch center teeth protruding radially outward from the outer cylinder portion and arranged in the circumferential direction, at least one of the output side rotating plates is held on the clutch center teeth, and a plurality of spline grooves are formed in the outer cylinder portion between adjacent clutch center teeth, and the plurality of spline grooves comprises a first spline groove having a first length in the circumferential direction and a second spline groove having a second length in the circumferential direction that is longer than the first length.

19. The clutch device according to claim 18, wherein the plurality of spline grooves have a third spline groove having a third length whose circumferential length is longer than the second length.

20. The clutch device according to claim 18, wherein the axial length of the clutch center teeth is longer than the axial length of the pressure plate teeth.

21. The clutch device according to claim 6, wherein the intertooth portion is located between adjacent pressure plate teeth in the circumferential direction and has first to fourth missing tooth portions whose circumferential length is longer than the predetermined interval, and when the pressure plate is viewed in the axial direction, the pressure plate is divided into first to fourth regions by a first straight line passing through the center of the output shaft and a second straight line passing through the center of the output shaft and perpendicular to the first straight line, and each of the first to fourth regions includes at least a portion of the first to fourth missing tooth portions.

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