Power transmission device

Abstract

To provide a power transmission device which can arbitrarily transmit or block a rotation force of an input member to an output member.SOLUTION: A power transmission device comprises centrifugal clutch means having a plurality of weight members which are movable to an outside-diameter side position from an inside-diameter position by a centrifugal force accompanied by the rotation of a clutch housing, and a pressure-contact member 12 for moving a drive-side clutch plate and a driven-side clutch plate in a direction in which the clutch plates pressure-contact with each other by the movement of the weight members to the outside-diameter position from the inside-diameter position. The weight members are constituted so as to make the drive-side clutch plate and the driven-side clutch plate pressure-contact with each other via the pressure-contact member 12 in a process in which the weight members move to the outside-diameter side position from the inside-diameter position, the pressure-contact member 12 has a circular body part and a plurality of protrusions K2 which are aligned in a circumferential direction of the body part, and the number of the plurality of protrusions K2 is an integer multiple of the number of the plurality of weight members, and the plurality of protrusions K2 are arranged while being separated from one another with respect to the circumferential direction.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a power transmission device that can arbitrarily transmit or interrupt a rotational force of an input member to an output member. [Background technology]

[0002] As a conventional power transmission device, for example, as disclosed in Patent Document 1, a centrifugal clutch means is proposed which includes a weight member that can press the driving clutch plate and the driven clutch plate together via a pressing member by moving from an inner diameter side position to an outer diameter side position by centrifugal force accompanying rotation of the clutch housing. According to this conventional power transmission device, the clutch housing rotates in conjunction with the driving of a drive source such as an engine, so that centrifugal force can be applied to the weight member, and the driving clutch plate and the driven clutch plate can be pressed together via the pressing member to transmit the driving force of the engine to the wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 183588 Summary of the Invention [Means for solving the problem]

[0004] The power transmission device according to the present invention comprises: a clutch member which rotates together with an input member which rotates by the driving force of a driving source, which is housed in a clutch housing which holds a plurality of driving side clutch plates, and which is connected to an output member capable of rotating a wheel; a pressure member which is provided so as to be able to approach or move away from the clutch member, and which is able to press a plurality of driven side clutch plates and the plurality of driving side clutch plates which are arranged alternately with the driving side clutch plates; a plurality of weight members which are movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying the rotation of the clutch housing; and a pressure contact member which is provided so as to be able to come into contact with the weight members, and which moves in a direction to press the driving side clutch plates and the driven side clutch plates together as the weight members move from the inner diameter side position to the outer diameter side position, and and a centrifugal clutch means which at a certain time presses the driving side clutch plate and the driven side clutch plate together to make the driving force of the driving source capable of being transmitted to the wheel, and which releases the pressing force between the driving side clutch plate and the driven side clutch plate when the weight member is in the inner diameter side position to cut off the transmission of the driving force of the driving source to the wheel, wherein the weight member is configured to press the driving side clutch plate and the driven side clutch plate together via the pressing member during the process of the weight member moving from the inner diameter side position to the outer diameter side position, and the pressing member has a circular main body portion and a plurality of convex portions protruding from the main body portion and aligned in the circumferential direction of the main body portion, the number of the multiple convex portions is an integer multiple of the number of the multiple weight members, and the multiple convex portions are arranged spaced apart from each other in the circumferential direction. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is an external view showing a power transmission device according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4]FIG. 4 is an exploded perspective view of the power transmission device according to the first embodiment. [Diagram 5] FIG. 5 is an exploded perspective view of the power transmission device according to the first embodiment. [Figure 6] FIG. 6 is an exploded perspective view of the centrifugal clutch means according to the first embodiment. [Figure 7] FIG. 7 is a perspective view showing the weight member according to the first embodiment. [Figure 8] FIG. 8 is a plan view and a rear view showing the weight member according to the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a perspective view showing the pressing member according to the first embodiment. [Figure 11] FIG. 11 is a plan view and a side view showing the pressing member according to the first embodiment. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 13 is a perspective view showing a holding member according to the first embodiment. [Figure 14] FIG. 14 is a sectional view showing the operation of the centrifugal clutch means according to the first embodiment (weight member in the inner diameter side position). [Figure 15] FIG. 15 is a sectional view showing the operation of the centrifugal clutch means according to the first embodiment (when the weight member is in a position between the inner diameter side position and the outer diameter side position). [Figure 16] FIG. 16 is a sectional view showing the operation of the centrifugal clutch means according to the first embodiment (weight member in outer diameter position). [Figure 17] FIG. 17 is a schematic diagram showing a vehicle to which the power transmission device according to the first embodiment is applied. [Figure 18] FIG. 18 is a perspective view showing a weight member according to the second embodiment. [Figure 19] FIG. 19 is a plan view and a rear view showing a weight member according to the second embodiment. [Figure 20] FIG. 20 is a cross-sectional view taken along the line XX-XX in FIG. [Figure 21] FIG. 21 is a sectional view showing the operation of the centrifugal clutch means according to the second embodiment (weight member in the inner diameter side position). [Figure 22] FIG. 22 is a sectional view showing the operation of the centrifugal clutch means according to the second embodiment (when the weight member is in a position between the inner diameter side position and the outer diameter side position). [Figure 23] FIG. 23 is a sectional view showing the operation of the centrifugal clutch means according to the second embodiment (weight member in outer diameter position). [Figure 24] FIG. 24 is a perspective view showing a weight member according to the third embodiment. [Diagram 25] FIG. 25 is a plan view and a rear view showing a weight member according to the third embodiment. [Figure 26] FIG. 26 is a cross-sectional view taken along line XXVI-XXVI in FIG. [Figure 27] FIG. 27 is a sectional view showing the operation of the centrifugal clutch means according to the third embodiment (weight member in the inner diameter side position). [Figure 28] FIG. 28 is a sectional view showing the operation of the centrifugal clutch means according to the third embodiment (when the weight member is in a position between the inner diameter side position and the outer diameter side position). [Figure 29] FIG. 29 is a sectional view showing the operation of the centrifugal clutch means according to the third embodiment (weight member in outer diameter position). [Diagram 30] FIG. 30 is a sectional view showing the operation of the centrifugal clutch means according to the fourth embodiment (weight member in the inner diameter side position). [Diagram 31] FIG. 31 is a sectional view showing the operation of the centrifugal clutch means according to the fourth embodiment (when the weight member is in a position between the inner diameter side position and the outer diameter side position). [Diagram 32] FIG. 32 is a sectional view showing the operation of the centrifugal clutch means according to the fourth embodiment (weight member in outer diameter position). [Diagram 33] FIG. 33 is a sectional view showing the operation of the centrifugal clutch means according to the fifth embodiment (weight member in the inner diameter side position). [Diagram 34]FIG. 34 is a sectional view showing the operation of the centrifugal clutch means according to the fifth embodiment (when the weight member is in a position between the inner diameter side position and the outer diameter side position). [Diagram 35] FIG. 35 is a sectional view showing the operation of the centrifugal clutch means according to the fifth embodiment (weight member in outer diameter position). [Diagram 36] FIG. 36 is a sectional view showing the operation of the centrifugal clutch means according to the sixth embodiment (weight member in the inner diameter side position). [Figure 37] FIG. 37 is a sectional view showing the operation of the centrifugal clutch means according to the sixth embodiment (when the weight member is in a position between the inner diameter side position and the radial side position). [Figure 38] FIG. 38 is a sectional view showing the operation of the centrifugal clutch means according to the sixth embodiment (weight member in outer diameter position). [Figure 39] FIG. 39 is a graph showing the relationship between the engine speed and the amount of movement of the pressing member. [Diagram 40] FIG. 40 is a graph showing the relationship between the engine speed and the thrust force exerted by the weight member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] First Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 17, a power transmission device K is disposed in a vehicle and is for arbitrarily transmitting or blocking the driving force of an engine E to a driving wheel T side via a transmission M. The engine E is an example of a driving source. The driving wheel T is an example of a wheel. As shown in FIGS. 1 to 16, the power transmission device K has a clutch housing 2 in which an input gear 1 that rotates by the driving force of the engine E of the vehicle is formed, an output shaft 3 connected to the transmission M, a clutch member 4, a pressure member 5, a plurality of driving side clutch plates 6 and a plurality of driven side clutch plates 7, and a centrifugal clutch means 9 having a weight member 10. In the drawings, the reference numeral 8 denotes a fixed member, the reference numeral S denotes a clutch spring, the reference numeral f denotes a return spring, and the reference numeral B denotes a bolt. The input gear 1 is an example of an input member. The output shaft 3 is an example of an output member.

[0007] The input gear 1 is configured to be rotatable about the output shaft 3 when a driving force (rotational force) transmitted from the engine E is input. The input gear 1 is connected to a clutch housing 2 by a rivet or the like. As shown in Figs. 4 and 5, the clutch housing 2 is formed in a cylindrical shape with one end open. The clutch housing 2 rotates together with the input gear 1 by the driving force of the engine E.

[0008] As shown in Figures 4 and 5, the clutch housing 2 has a plurality of notches 2a formed in the circumferential direction. A plurality of driving side clutch plates 6 are fitted into the notches 2a and attached. That is, the clutch housing 2 holds a plurality of driving side clutch plates 6. The driving side clutch plates 6 are made of a plate material having a substantially annular shape. The driving side clutch plates 6 are configured to be movable along the axial direction of the clutch housing 2 (i.e., the axial direction of the output shaft 3) and to be rotatable integrally with the clutch housing 2.

[0009] As shown in Fig. 2, the clutch member 4 is accommodated in a clutch housing 2. The clutch member 4 holds a plurality of driven-side clutch plates 7 arranged alternately with driving-side clutch plates 6. The clutch member 4 is connected to an output shaft 3 capable of rotating driving wheels T via a transmission M of a vehicle. As shown in Figs. 4 and 5, the clutch member 4 includes a first clutch member 4a and a second clutch member 4b. The first clutch member 4a is fitted into the second clutch member 4b.

[0010] As shown in FIG. 4 and FIG. 5, the first clutch member 4a has an insertion hole 4ac formed in the center. The output shaft 3 is inserted into the insertion hole 4ac, and the splines formed in the insertion hole 4ac mesh with each other to couple in the rotational direction. That is, the first clutch member 4a is coupled to the output shaft 3. The second clutch member 4b has an outer peripheral wall 4bc formed in an annular shape and a flange portion 4bb extending radially outward from the outer peripheral wall 4bc. The outer peripheral wall 4bc is formed with a spline fitting portion 4ba. The spline fitting portion 4ba has a concave-convex shape integrally formed over substantially the entire circumference of the outer peripheral wall 4bc. The driven-side clutch plate 7 is attached to the concave groove of the spline fitting portion 4ba by spline fitting. That is, the second clutch member 4b holds the driven-side clutch plate 7. The driven clutch plate 7 is configured to be movable along the axial direction of the clutch member 4 (e.g., the second clutch member 4b) (i.e., the axial direction of the output shaft 3) and to be rotatable integrally with the clutch member 4 (e.g., the first clutch member 4a and the second clutch member 4b). The second clutch member 4b is configured to be movable in the axial direction of the output shaft 3.

[0011] As shown in Fig. 4, the pressure member 5 is made of a disk-shaped member having a flange portion 5a formed on its peripheral edge. The pressure member 5 is attached to the clutch member 4. The pressure member 5 is provided so as to be able to approach or move away from the clutch member 4. The pressure member 5 is configured so as to be able to press the driving side clutch plate 6 and the driven side clutch plate 7 together. The pressure member 5 is configured so as to be able to press the driving side clutch plate 6 and the driven side clutch plate 7 together with the clutch member 4. The pressure member 5 presses the driving side clutch plate 6 and the driven side clutch plate 7 together, thereby transmitting the driving force of the engine E to the driving wheels W. That is, the driving side clutch plates 6 and the driven side clutch plates 7 are arranged in a stacked state between the flange portion 5a of the pressure member 5 and the flange portion 4bb of the second clutch member 4b, and when the second clutch member 4b moves in a direction approaching the pressure member 5 (the direction of the arrow DR2 in FIG. 2), the driving side clutch plates 6 and the driven side clutch plates 7 are pressed together, and the rotational force of the clutch housing 2 is transmitted to the output shaft 3 via the second clutch member 4b and the first clutch member 4a. On the other hand, when the second clutch member 4b moves in a direction away from the pressure member 5 (the direction of the arrow DR1 in FIG. 2), the pressing force of the driving side clutch plates 6 and the driven side clutch plates 7 is released, and the first clutch member 4a and the second clutch member 4b no longer follow the rotation of the clutch housing 2, and the rotational force of the clutch housing 2 is no longer transmitted to the output shaft 3. The driving side clutch plates 6 and the driven side clutch plates 7 are provided so as to be movable in the axial direction of the output shaft 3 relative to the second clutch member 4b.

[0012] In this manner, when the driving side clutch plates 6 and the driven side clutch plates 7 are in pressure contact with each other, the rotational force input to the clutch housing 2 (i.e., the driving force of the engine E) is transmitted to the driving wheels T (i.e., the transmission M) via the output shaft 3. On the other hand, when the driving side clutch plates 6 and the driven side clutch plates 7 are released from the pressure contact, the rotational force input to the clutch housing 2 is not transmitted to the output shaft 3.

[0013] As shown in FIG. 2, the centrifugal clutch means 9 has a weight member 10 that can move from an inner diameter side position (see FIG. 14) to an outer diameter side position (see FIG. 16) by centrifugal force accompanying the rotation of the clutch housing 2. The centrifugal clutch means 9 is disposed on the opening side (right side in FIG. 2) of the clutch housing 2. The centrifugal clutch means 9 is disposed on the opposite side of the pressure member 5 with the driving side clutch plate 6 and the driven side clutch plate 7 sandwiched therebetween. Here, the centrifugal clutch means 9 is disposed on the arrow DR1 direction side of the pressure member 5 in FIG. 2. When the weight member 10 is in the outer diameter side position, the centrifugal clutch means 9 presses the driving side clutch plate 6 and the driven side clutch plate 7 together to make it possible to transmit the driving force of the engine E to the driving wheels T. The centrifugal clutch means 9 is configured to apply a pressing force to the driving side clutch plate 6 and the driven side clutch plate 7 in the process of the weight member 10 moving from the inner diameter side position to the outer diameter side position. The centrifugal clutch means 9 is configured to release the pressing force between the driving side clutch plate 6 and the driven side clutch plate 7 when the weight member 10 is in the inner diameter side position, thereby cutting off the transmission of the driving force of the engine E to the driving wheels T. In other words, the centrifugal clutch means 9 is configured to release the pressing force applied to the driving side clutch plate 6 and the driven side clutch plate 7 when the weight member 10 is in the inner diameter side position, thereby cutting off the transmission of the driving force of the engine E to the driving wheels T.

[0014] As shown in FIG. 6, the centrifugal clutch means 9 has a plurality of weight members 10, a holding member 11 that holds the weight members 10 movably between an inner diameter side position and an outer diameter side position, a pressure contact member 12, and a plurality of biasing springs 13.

[0015] As shown in Figs. 7 to 9, the weight member 10 has a main body 10h, a weight member-side cam surface K1 formed on the main body 10h, a groove 10c formed on the main body 10h and holding the biasing spring 13 (see Fig. 6), and a sliding surface 10d formed on the main body 10h and capable of sliding against a sliding surface 11b (see Fig. 13) of the holding member 11. The weight member 10 is accommodated in the holding member 11. The weight member 10 is held at an inner diameter side position (see Fig. 14) when no centrifugal force is applied. When centrifugal force is applied, the weight member 10 moves radially outward against the biasing force of the biasing spring 13 and reaches an outer diameter side position (see Fig. 16). In the process of moving from the inner diameter side position to the outer diameter side position, the weight member 10 moves the clutch member 4 (here, the second clutch member 4b) in a direction approaching the pressure member 5 (the direction of the arrow DR2 in Fig. 2). The weight member 10 is configured to press the driving side clutch plate 6 and the driven side clutch plate 7 together via the pressing member 12 during the process of the weight member 10 moving from the inner diameter side position to the outer diameter side position. Note that the weight member 10 does not need to press the driving side clutch plate 6 and the driven side clutch plate 7 together via the pressing member 12 at the same time as it starts to move from the inner diameter side position to the outer diameter side position, and the driving side clutch plate 6 and the driven side clutch plate 7 may be pressed together via the pressing member 12 after the weight member 10 has moved a predetermined distance from the inner diameter side position to the outer diameter side position.

[0016] As shown in FIG. 14, the weight member side cam surface K1 is provided so as to be able to come into contact with the pressing member side cam surface K2, which will be described later. The weight member side cam surface K1 is a portion that comes into contact with the pressing member 12. As shown in FIG. 9, the weight member 10 has a first gradient surface 10a and a second gradient surface 10b, which has a larger gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 10a, on the weight member side cam surface K1. The first gradient surface 10a is located radially outward from the second gradient surface 10b. The first gradient surface 10a is a flat surface. The second gradient surface 10b is a flat surface. The gradient angle α of the first gradient surface 10a with respect to the axial direction of the output shaft 3 is smaller than the gradient angle β of the second gradient surface 10b with respect to the axial direction of the output shaft 3. In this embodiment, the first gradient surface 10a and the second gradient surface 10b are continuous, but may be connected via a curved surface. In this way, the centrifugal clutch means 9 has a first gradient surface 10a and a second gradient surface 10b at a portion of the weight member 10 where the weight member 10 and the pressing member 12 contact each other (here, the weight member side cam surface K1). When the engine speed increases by a predetermined speed and the weight member 10 moves a predetermined distance in the radial direction, the amount of movement of the pressing member 12 in the axial direction of the output shaft 3 at the second gradient surface 10b is smaller than the amount of movement of the pressing member 12 in the axial direction of the output shaft 3 at the first gradient surface 10a. The thrust of the weight member 10 generated at the second gradient surface 10b is larger than the thrust of the weight member 10 generated at the first gradient surface 10a. The first gradient surface 10a is an example of a first region. The second gradient surface 10b is an example of a second region.

[0017] As shown in Fig. 2, the holding member 11 holds the weight member 10 movably between an inner diameter side position and an outer diameter side position. As shown in Fig. 13, the holding member 11 has an annular main body portion 11c, a wall portion 11a extending from the outer periphery of the main body portion 11c, and a sliding surface 11b on which the weight member 10 slides. The wall portion 11a comes into contact with one end of the biasing spring 13.

[0018] The pressing member 12 is provided so as to be able to come into contact with the weight member 10. The pressing member 12 is configured to move in a direction (the direction of the arrow DR2 in FIG. 14) in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together by the weight member 10 moving from the inner diameter side position (see FIG. 14) to the outer diameter side position (see FIG. 16). The pressing member 12 is configured so as to be able to press the driving side clutch plate 6 and the driven side clutch plate 7 together. As shown in FIG. 10 to FIG. 12, the pressing member 12 has an annular main body portion 12d, a plurality of pressing member side cam faces K2 formed around the circumferential direction of the main body portion 12d, a pressing face 12c formed on the surface of the main body portion 12d opposite to the surface on which the pressing member side cam face K2 is formed, and a plurality of protrusions 12e formed around the circumferential direction of the main body portion 12d. The pressing member 12 is attached to the clutch housing 2 by fitting the protrusion 12e into the notch 2a (see FIG. 4) of the clutch housing 2. The pressing member 12 is provided so as to be movable in the axial direction of the clutch housing 2 (i.e., the axial direction of the output shaft 3). The pressing member 12 engages with the clutch housing 2 in the rotational direction and is provided so as to be rotatable together with the clutch housing 2.

[0019] As shown in FIG. 14, the pressing member side cam surface K2 is provided so as to be able to come into contact with the weight member side cam surface K1. The pressing member side cam surface K2 is a portion that comes into contact with the weight member 10. As shown in FIG. 12, the pressing member 12 has a first gradient surface 12a and a second gradient surface 12b, which has a larger gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 12a, on the pressing member side cam surface K2. The first gradient surface 12a is located radially inward from the second gradient surface 12b. The first gradient surface 12a is a flat surface. The second gradient surface 12b is a flat surface. The gradient angle α of the first gradient surface 12a with respect to the axial direction of the output shaft 3 is smaller than the gradient angle β of the second gradient surface 12b with respect to the axial direction of the output shaft 3. The first gradient surface 12a is provided so as to be able to come into contact with the first gradient surface 10a of the weight member side cam surface K1. The second gradient surface 12b is provided so as to be able to come into contact with the second gradient surface 10b of the weight member side cam surface K1. In this embodiment, the first gradient surface 12a and the second gradient surface 12b are continuous, but may be connected via a curved surface. In this manner, the centrifugal clutch means 9 has the first gradient surface 12a and the second gradient surface 12b at a portion (here, the pressure member side cam surface K2) where the weight member 10 of the pressure member 12 contacts the pressure member 12. When the engine speed increases by a predetermined speed and the weight member 10 moves a predetermined distance in the radial direction, the amount of movement of the pressure member 12 in the axial direction of the output shaft 3 on the second gradient surface 12b is smaller than the amount of movement of the pressure member 12 in the axial direction of the output shaft 3 on the first gradient surface 12a. The thrust of the weight member 10 generated on the second gradient surface 12b is larger than the thrust of the weight member 10 generated on the first gradient surface 12a. The first gradient surface 12a is an example of a first region. The second inclined surface 12b is an example of the second region.

[0020] The thrust of the weight member 10, which is generated in the process of the weight member 10 moving from the inner diameter side position (see FIG. 14) to the outer diameter side position (see FIG. 16), is transmitted to the pressing member 12 via the weight member side cam surface K1 and the pressing member side cam surface K2. As a result, the pressing member 12 moves in a direction (the direction of the arrow DR2 in FIG. 14) in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed into contact with each other. As shown in FIG. 14 to FIG. 16, the weight member side cam surface K1 and the pressing member side cam surface K2 are configured so that the gradient surface acting as a cam surface transitions from the first gradient surface 10a and the first gradient surface 12a to the second gradient surface 10b and the second gradient surface 12b in the process of the weight member 10 moving from the inner diameter side position (see FIG. 14) to the outer diameter side position (see FIG. 16). In the process of the weight member 10 moving from the inner diameter side position to the outer diameter side position, before the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed together, the first inclined surface 10a and the first inclined surface 12a act as cam surfaces, and after the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed together, the second inclined surface 10b and the second inclined surface 12b act as cam surfaces.

[0021] As shown in Fig. 14, in the process of the weight member 10 moving from the inner diameter side position to the outer diameter side position, the first gradient surface 10a and the first gradient surface 12a contact and slide on each other on the weight member side cam surface K1 and the pressing member side cam surface K2 before the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other. As a result, the thrust force generated when the weight member 10 moves from the inner diameter side position to the outer diameter side position is transmitted to the pressing member 12 via the first gradient surface 10a and the first gradient surface 12a. Then, the pressing member 12 moves in a direction in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed against each other (the direction of the arrow DR2 in Fig. 14). At this time, the thrust force of the weight member 10 transmitted to the pressing member 12 becomes relatively small, but the amount of movement of the pressing member 12 in the axial direction of the output shaft 3 becomes relatively large.

[0022] Then, as shown in Figure 15, when the weight member 10 moves further from the inner diameter side position to the outer diameter side position and the driving side clutch plate 6 and the driven side clutch plate 7 begin to be pressed together, the boundary between the first sloped surface 10a and the second sloped surface 10b of the weight member side cam surface K1 and the boundary between the first sloped surface 12a and the second sloped surface 12b of the pressing member side cam surface K2 come into contact with each other.

[0023] Then, as shown in Fig. 16, when the weight member 10 moves further from the inner diameter side position to the outer diameter side position, the second gradient surface 10b and the second gradient surface 12b come into contact with each other and slide on each other after the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other at the weight member side cam surface K1 and the pressing member side cam surface K2. As a result, the thrust force generated when the weight member 10 moves from the inner diameter side position to the outer diameter side position is transmitted to the pressing member 12 via the second gradient surface 10b and the second gradient surface 12b. Then, the pressing member 12 moves further in the direction in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed against each other (the direction of the arrow DR2 in Fig. 16). At this time, the amount of movement of the pressing member 12 in the axial direction of the output shaft 3 becomes relatively small, but the thrust force of the weight member 10 transmitted to the pressing member 12 becomes relatively large.

[0024] In addition, the weight member 10 and the pressing member 12 may be configured to come into contact with each other at the first gradient surface 10a and the first gradient surface 12a (i.e., come into contact with each other in the first region) and then come into contact with each other at the second gradient surface 10b and the second gradient surface 12b (i.e., come into contact with each other in the second region) when the rotation speed of the engine E increases. Also, when the rotation speed of the engine E is lower than the rotation speed when the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other, the weight member 10 and the pressing member 12 may be configured to come into contact with each other at the first gradient surface 10a and the first gradient surface 12a (i.e., come into contact with each other in the first region) and then come into contact with each other at the second gradient surface 10b and the second gradient surface 12b (i.e., come into contact with each other in the second region) when the rotation speed of the engine E is lower than the rotation speed when the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other. When the rotation speed of the engine E is lower than the rotation speed when the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is completed, the weight member 10 and the pressing member 12 may be configured to come into contact with each other at the first inclined surface 10a and the first inclined surface 12a (i.e., come into contact with each other in the first region) and then come into contact with each other at the second inclined surface 10b and the second inclined surface 12b (i.e., come into contact with each other in the second region). Note that in a region where the rotation speed of the engine E is higher than the rotation speed of the engine E when the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is completed, the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is maintained.

[0025] Fig. 39 is a graph showing the relationship between the rotation speed of the engine E and the amount of axial movement of the output shaft 3 of the pressure contact member 12. In Fig. 39, the horizontal axis shows the rotation speed of the engine E, and the vertical axis shows the amount of axial movement of the output shaft 3 of the pressure contact member 12. Fig. 40 is a graph showing the relationship between the rotation speed of the engine E and the thrust force by the weight member 10. In Fig. 40, the horizontal axis shows the rotation speed of the engine E, and the vertical axis shows the thrust force by the weight member 10. In Figures 39 and 40, the rotation speed EID indicates the rotation speed of the engine E in an idling state, the rotation speed EC indicates the rotation speed of the engine E when the driving side clutch plates 6 and the driven side clutch plates 7 begin to be pressed together (here, when the inclined surfaces acting as cam surfaces transition from the first inclined surfaces 10a and 12a to the second inclined surfaces 10b and 12b), the rotation speed EIN indicates the rotation speed of the engine E when the driving force of the engine E begins to be transmitted to the driving wheels T, the rotation speed EST indicates the rotation speed of the engine E when the driving side clutch plates 6 and the driven side clutch plates 7 are completely pressed together (when the pressing of the driving side clutch plates 6 and the driven side clutch plates 7 is completed), and the rotation speed EE indicates the rotation speed of the engine E when the weight member 10 reaches the outer diameter side position. 39 and 40, when the rotation speed of the engine E is between rotation speed EID and rotation speed EC, the amount of movement LM1 of the output shaft 3 of the pressing member 12 in the axial direction is relatively large, and the thrust force FM1 by the weight member 10 is relatively small. On the other hand, when the rotation speed of the engine E is between rotation speed EC and rotation speed EE, the amount of movement LM2 of the output shaft 3 of the pressing member 12 in the axial direction is relatively small (movement amount LM2<movement amount LM1), and the thrust force FM2 by the weight member 10 is relatively large (thrust force FM2>thrust force FM1).

[0026] As described above, in the power transmission device K of this embodiment, the centrifugal clutch means 9 has, on the weight member side cam surface K1, the first inclined surfaces 10a, 12a and the second inclined surfaces 10b, 12b having larger inclination angles with respect to the axial direction of the output shaft 3 than the first inclined surfaces 10a, 12a. According to the above aspect, the required amount of movement of the pressing member 12 in the axial direction of the output shaft 3 and the thrust force by the weight member 10 can be secured according to the operating state.

[0027] In the power transmission device K of this embodiment, the weight member 10 and the pressure contact member 12 may come into contact with each other at the first inclined surfaces 10a and 12a, and then come into contact with each other at the second inclined surfaces 10b and 12b, during the process of increasing the rotation speed of the engine E. According to the above embodiment, the amount of axial movement of the pressure contact member 12 is first increased, and then the thrust force by the weight member 10 can be increased.

[0028] In the power transmission device K of this embodiment, the first gradient surface 10a and the second gradient surface 10b may be connected via a curved surface, and the first gradient surface 12a and the second gradient surface 12b may be connected via a curved surface. According to the above aspect, the first gradient surface 10a and the second gradient surface 10b are connected via a curved surface, and the first gradient surface 12a and the second gradient surface 12b are connected via a curved surface, so that the contact portion between the weight member 10 and the pressing member 12 can be smoothly shifted from the first gradient surfaces 10a, 12a to the second gradient surfaces 10b, 12b.

[0029] In the power transmission device K of this embodiment, when the rotation speed of the engine E is lower than the rotation speed when the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other, the weight member 10 and the pressing member 12 may come into contact with each other at the first gradient surfaces 10a, 12a and then come into contact with each other at the second gradient surfaces 10b, 12b. According to the above-mentioned embodiment, when the rotation speed is lower than the rotation speed when the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other, the contact portion between the weight member 10 and the pressing member 12 is shifted from the first gradient surfaces 10a, 12a to the second gradient surfaces 10b, 12b. Therefore, the necessary amount of movement of the pressing member 12 in the axial direction of the output shaft 3 can be secured before the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other, and the necessary thrust by the weight member 10 can be secured after the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other.

[0030] In the power transmission device K of this embodiment, when the rotation speed of the engine E is lower than the rotation speed when the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is completed, the weight member 10 and the pressing member 12 may come into contact with each other at the first gradient surfaces 10a, 12a and then come into contact with each other at the second gradient surfaces 10b, 12b. According to the above embodiment, when the rotation speed is lower than the rotation speed when the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is completed, the contact portion between the weight member 10 and the pressing member 12 is shifted from the first gradient surfaces 10a, 12a to the second gradient surfaces 10b, 12b. Therefore, it is possible to ensure the necessary amount of movement of the pressing member 12 in the axial direction of the output shaft 3 until the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is completed, and it is possible to ensure the necessary thrust by the weight member 10 after the pressing contact between the driving side clutch plate 6 and the driven side clutch plate 7 is completed.

[0031] In the power transmission device K of this embodiment, the weight member 10 has a sliding surface 10d that is slidable against the holding member 11, the weight member 10 has a first gradient surface 10a and a second gradient surface 10b at a portion where the weight member 10 and the pressing member 12 contact each other (for example, the weight member side cam surface K1), and the pressing member 12 may have a first gradient surface 12a and a second gradient surface 12b at a portion where the weight member 10 and the pressing member 12 contact each other (for example, the pressing member side cam surface K2). According to the above aspect, the weight member 10 having the sliding surface 10d that is slidable against the holding member 11 can be suitably applied.

[0032] Furthermore, in the power transmission device K of this embodiment, the centrifugal clutch means 9 has the first inclined surfaces 10a, 12a as the first region, and the second inclined surfaces 10b, 12b as the second region in which the amount of movement of the pressing member 12 in the axial direction of the output shaft 3 is smaller than that in the first region. According to the above aspect, it is possible to ensure the necessary amount of movement of the pressing member 12 in the axial direction of the output shaft 3 and the thrust by the weight member 10 depending on the operating state. Note that the thrust by the weight member 10 is larger in the second region than in the first region.

[0033] In the power transmission device K of this embodiment, the weight member 10 and the pressing member 12 may come into contact with each other at the first inclined surfaces 10a, 12a as the first region and then come into contact with each other at the second inclined surfaces 10b, 12b as the second region in the process of increasing the rotation speed of the engine E. According to the above embodiment, the amount of axial movement of the pressing member 12 is first increased, and then the thrust by the weight member 10 can be increased.

[0034] In the power transmission device K of this embodiment, the first region may be the first gradient surfaces 10a, 12a made of flat surfaces, and the second region may be the second gradient surfaces 10b, 12b made of flat surfaces, and the weight member 10 and the pressing member 12 may be configured to be able to come into contact with each other at the first gradient surfaces 10a, 12a and the second gradient surfaces 10b, 12b. According to the above aspect, the amount of movement of the pressing member 12 and the thrust by the weight member 10 can be smoothly changed in the first region and the second region.

[0035] <Second embodiment> 21 to 23, a power transmission device 200K according to the second embodiment has a centrifugal clutch means 209 having a weight member 14. Note that the same components as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0036] As shown in FIG. 21, the centrifugal clutch means 209 has a plurality of weight members 14, a retaining member 11 that retains the weight members 14 movably between an inner diameter side position and an outer diameter side position, a pressure contact member 15, and a plurality of biasing springs 13.

[0037] 18 to 20, weight member 14 is configured to be movable from an inner diameter side position (see FIG. 21) to an outer diameter side position (see FIG. 23) by centrifugal force accompanying rotation of clutch housing 2. Weight member 14 has a main body portion 14h, a spherical member 14a that is in point contact with holding member 11 or that can move while rolling, a holding hole 14f that is formed in main body portion 14h and that holds spherical member 14a, and a groove portion 14b that is formed in main body portion 14h and that holds biasing spring 13. Spherical member 14a is an example of a contact portion.

[0038] The pressing member 15 is provided so as to be able to come into contact with the weight member 14. The pressing member 15 is configured to move in a direction (the direction of the arrow DR2 in FIG. 21) in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together by the weight member 14 moving from the inner diameter side position (see FIG. 21) to the outer diameter side position (see FIG. 23). The pressing member 15 is configured so as to be able to press the driving side clutch plate 6 and the driven side clutch plate 7 together. As shown in FIG. 21, the pressing member 15 has a pressing member side cam surface 200K2 formed around the circumferential direction of the main body portion 12d.

[0039] As shown in FIG. 21, the pressing member side cam surface 200K2 is provided so as to be able to come into contact with the spherical member 14a. The pressing member side cam surface 200K2 is a portion that comes into contact with the weight member 14. The pressing member 15 has a first gradient surface 15a and a second gradient surface 15b, which has a gradient angle with respect to the axial direction of the output shaft 3 larger than that of the first gradient surface 15a, on the pressing member side cam surface 200K2. The first gradient surface 15a is located radially inward of the second gradient surface 15b. The first gradient surface 15a is a flat surface. The second gradient surface 15b is a curved surface. The first gradient surface 15a and the second gradient surface 15b are provided so as to be able to come into contact with the spherical member 14a. In this embodiment, the first gradient surface 15a and the second gradient surface 15b are continuous, but may be connected via a curved surface. When the engine speed increases by a predetermined number of revolutions and the weight member 10 moves a predetermined distance in the radial direction, the amount of movement of the pressure contact member 15 in the axial direction of the output shaft 3 at the second gradient surface 15b is smaller than the amount of movement of the pressure contact member 15 in the axial direction of the output shaft 3 at the first gradient surface 15a. Also, when the engine speed increases by a predetermined number of revolutions and the weight member 10 moves a predetermined distance in the radial direction, the thrust of the weight member 14 generated at the second gradient surface 15b is larger than the thrust of the weight member 14 generated at the first gradient surface 15a. The first gradient surface 15a is an example of a first region. The second gradient surface 12b is an example of a second region.

[0040] The thrust of the weight member 14, which is generated in the process of the weight member 14 moving from the inner diameter side position (see FIG. 21) to the outer diameter side position (see FIG. 23), is transmitted to the pressing member 15 via the spherical member 14a and the pressing member side cam surface 200K2. As a result, the pressing member 15 moves in a direction (the direction of the arrow DR2 in FIG. 21) in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together. As shown in FIG. 21 to FIG. 23, the spherical member 14a and the pressing member side cam surface 200K2 are configured so that the inclined surface acting as a cam surface for the spherical member 14a transitions from the first inclined surface 15a to the second inclined surface 15b in the process of the weight member 14 moving from the inner diameter side position (see FIG. 21) to the outer diameter side position (see FIG. 23). In the process of the weight member 14 moving from the inner diameter side position to the outer diameter side position, before the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed together, the first inclined surface 15a acts as a cam surface, and after the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed together, the second inclined surface 15b acts as a cam surface.

[0041] As shown in Fig. 21, in the process of the weight member 14 moving from the inner diameter side position to the outer diameter side position, the spherical member 14a and the first gradient surface 15a contact and slide on each other at the spherical member 14a and the pressing member side cam surface K2 before the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other. As a result, the thrust force generated when the weight member 14 moves from the inner diameter side position to the outer diameter side position is transmitted to the pressing member 15 via the spherical member 14a and the first gradient surface 15a. Then, the pressing member 15 moves in a direction in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed against each other (the direction of the arrow DR2 in Fig. 21). At this time, the thrust force of the weight member 14 transmitted to the pressing member 15 becomes relatively small, but the amount of movement of the pressing member 15 in the axial direction of the output shaft 3 becomes relatively large.

[0042] Then, as shown in Figure 22, when the weight member 14 moves further from the inner diameter side position to the outer diameter side position and the driving side clutch plate 6 and the driven side clutch plate 7 begin to be pressed together, the spherical member 14a and the boundary between the first inclined surface 15a and the second inclined surface 15b of the pressing member side cam surface 200K2 come into contact with each other.

[0043] Then, as shown in Fig. 23, when the weight member 14 moves further from the inner diameter side position to the outer diameter side position, the spherical member 14a and the second gradient surface 15b come into contact with each other and slide on each other after the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed against each other by the spherical member 14a and the pressing member side cam surface 200K2. As a result, the thrust force generated when the weight member 14 moves from the inner diameter side position to the outer diameter side position is transmitted to the pressing member 15 via the spherical member 14a and the second gradient surface 15b. Then, the pressing member 15 moves further in the direction in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed against each other (the direction of the arrow DR2 in Fig. 23). At this time, the amount of movement of the pressing member 15 in the axial direction of the output shaft 3 becomes relatively small, but the thrust force of the weight member 14 transmitted to the pressing member 15 becomes relatively large.

[0044] In the power transmission device 200K of this embodiment, the weight member 14 has a spherical member 14a that is movable while making point contact with the holding member 11, and the pressing member 15 has a first inclined surface 15a and a second inclined surface 15b on the pressing member side cam surface 200K2. According to the above aspect, the weight member 14 having the spherical member 14a that is movable while making point contact with the holding member 11 can be effectively used.

[0045] <Third embodiment> 27 to 29, a power transmission device 300K according to the third embodiment has a centrifugal clutch means 309 having a weight member 16. Note that the same components as those in the first and second embodiments are given the same reference numerals, and detailed description thereof will be omitted.

[0046] As shown in Figs. 24 to 26, the weight member 16 is configured to be movable from an inner diameter side position (see Fig. 27) to an outer diameter side position (see Fig. 29) by centrifugal force accompanying the rotation of the clutch housing 2. The weight member 16 has a main body portion 16h, a pair of rolling members 16a, 16b that are movable while making point contact or rolling with respect to the holding member 11, a holding hole 16f formed in the main body portion 16h and holding the rolling members 16a, 16b, and a groove portion 16c formed in the main body portion 16h and holding the biasing spring 13. The rolling member 16a is provided so as to be able to come into contact with the pressing member side cam surface 200K2. The rolling member 16b is provided so as to be able to come into contact with the holding member 11. The rolling members 16a, 16b are held in the holding hole 16f so as to come into contact with each other. The rolling members 16a, 16b are an example of a contact portion.

[0047] The thrust of the weight member 16, which is generated in the process of the weight member 16 moving from the inner diameter side position (see FIG. 27) to the outer diameter side position (see FIG. 29), is transmitted to the pressing member 15 via the rolling members 16a, 16b and the pressing member side cam surface 200K2. As a result, the pressing member 15 moves in a direction (the direction of the arrow DR2 in FIG. 27) in which the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together. As shown in FIG. 27 to FIG. 29, the rolling member 16a and the pressing member side cam surface 200K2 are configured so that the gradient surface acting as a cam surface for the rolling member 16a transitions from the first gradient surface 15a to the second gradient surface 15b in the process of the weight member 16 moving from the inner diameter side position (see FIG. 27) to the outer diameter side position (see FIG. 29). In the process of weight member 16 moving from the inner diameter side position to the outer diameter side position, before the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed together, first inclined surface 15a acts as a cam surface, and after the driving side clutch plate 6 and the driven side clutch plate 7 start to be pressed together, second inclined surface 15b acts as a cam surface. Note that the action and effect of the third embodiment are similar to the action and effect of the second embodiment.

[0048] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

[0049] <Fourth embodiment> In the first embodiment described above, the centrifugal clutch means 9 is disposed on the opening side of the clutch housing 2 (the right side in FIG. 2), but is not limited thereto. For example, in the power transmission device 400K according to the fourth embodiment, as shown in FIGS. 30 to 32, the centrifugal clutch means 9 may be disposed on the bottom side of the clutch housing 2 (the left side in FIG. 30). The centrifugal clutch means 9 is disposed on the opposite side of the pressure member 5 across the driving side clutch plate 6 and the driven side clutch plate 7. Here, the centrifugal clutch means 9 is disposed on the arrow DR2 direction side in FIG. 30 relative to the clutch member 4 (more specifically, the second clutch member 4b).

[0050] <Fifth embodiment> In the second embodiment described above, the centrifugal clutch means 209 is disposed on the opening side of the clutch housing 2 (the right side in FIG. 21), but is not limited thereto. For example, in the power transmission device 500K according to the fifth embodiment, as shown in FIGS. 33 to 35, the centrifugal clutch means 209 may be disposed on the bottom side of the clutch housing 2 (the left side in FIG. 33). The centrifugal clutch means 209 is disposed on the opposite side of the pressure member 5 across the driving side clutch plate 6 and the driven side clutch plate 7. Here, the centrifugal clutch means 209 is disposed on the arrow DR2 direction side of the clutch member 4 (more specifically, the second clutch member 4b) in FIG. 33.

[0051] Sixth Embodiment In the third embodiment described above, the centrifugal clutch means 309 is disposed on the opening side of the clutch housing 2 (the right side in FIG. 27), but is not limited thereto. For example, in the power transmission device 600K according to the sixth embodiment, as shown in FIGS. 36 to 38, the centrifugal clutch means 309 may be disposed on the bottom side of the clutch housing 2 (the left side in FIG. 36). The centrifugal clutch means 309 is disposed on the opposite side of the pressure member 5 across the driving side clutch plate 6 and the driven side clutch plate 7. Here, the centrifugal clutch means 309 is disposed on the arrow DR2 direction side in FIG. 36 relative to the clutch member 4 (more specifically, the second clutch member 4b).

[0052] In the above-mentioned embodiment, the centrifugal clutch means 9 has the first gradient surface 10a and the second gradient surface 10b on the weight member side cam surface K1, and has the first gradient surface 12a and the second gradient surface 12b on the pressure member side cam surface K2, but is not limited to this. The centrifugal clutch means 9 may have the first gradient surface 10a and the second gradient surface 10b on the weight member side cam surface K1, and may not have the first gradient surface 12a and the second gradient surface 12b on the pressure member side cam surface K2. Also, the centrifugal clutch means 9 may not have the first gradient surface 10a and the second gradient surface 10b on the weight member side cam surface K1, and may have the first gradient surface 12a and the second gradient surface 12b on the pressure member side cam surface K2.

[0053] In the above-described embodiment, the first gradient surface 10a, the second gradient surface 10b, the first gradient surface 12a, and the second gradient surface 12b are flat surfaces, but they may be curved surfaces. In addition, when at least one of the first gradient surface 10a and the second gradient surface 10b is a curved surface, it is preferable that the first gradient surface 12a and the second gradient surface 12b are a curved surface, and the first gradient surface 10a and the second gradient surface 12b are a curved surface, and the first gradient surface 10a and the second gradient surface 12b are a curved surface, and the first gradient surface 10a and the second gradient surface 12b are a curved surface, and the first gradient surface 10a and the second gradient surface 12b are a curved surface, and the first gradient surface 12 ....

[0054] In the above-described embodiment, the weight member 10 has, on the weight-member-side cam surface K1, the first gradient surface 10a and the second gradient surface 10b having a larger gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 10a, but is not limited thereto. The weight member 10 may have a third gradient surface radially outward of the first gradient surface 10a and having a smaller gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 10a. The weight member 10 may also have a fourth gradient surface radially inward of the second gradient surface 10b and having a larger gradient angle with respect to the axial direction of the output shaft 3 than the second gradient surface 10b.

[0055] In the above-described embodiment, the pressing member 12 has, on the pressing member side cam surface K2, the first gradient surface 12a and the second gradient surface 12b having a larger gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 12a, but is not limited thereto. The pressing member 12 may have a third gradient surface radially inward from the first gradient surface 12a and having a smaller gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 12a. The pressing member 12 may also have a fourth gradient surface radially outward from the second gradient surface 12b and having a larger gradient angle with respect to the axial direction of the output shaft 3 than the second gradient surface 12b.

[0056] In the above-described embodiment, the pressing member 15 has, on the pressing member side cam surface 200K2, the first gradient surface 15a and the second gradient surface 15b having a larger gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 15a, but is not limited thereto. The pressing member 15 may have a third gradient surface radially inward from the first gradient surface 15a and having a smaller gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surface 15a. The pressing member 15 may also have a fourth gradient surface radially outward from the second gradient surface 15b and having a larger gradient angle with respect to the axial direction of the output shaft 3 than the second gradient surface 15b.

[0057] In the above-described embodiment, all the driven-side clutch plates 7 are held by the clutch member 4 (e.g., the second clutch member 4b), but this is not limiting. For example, some of the driven-side clutch plates 7 may be held by the clutch member 4 (e.g., the second clutch member 4b), and another part of the driven-side clutch plates 7 may be held by the pressure member 5. In this case, the other part of the driven-side clutch plates 7 is configured to be movable along the axial direction of the pressure member 5 (i.e., the axial direction of the output shaft 3) and to be rotatable integrally with the pressure member 5.

[0058] In each of the above-described embodiments, the engine E is used as the drive source, but the drive source is not limited to the engine E and may be, for example, an electric motor or the like.

[0059] The power transmission devices of the above-described embodiments can be applied to various multi-plate clutch type power transmission devices in motorcycles, automobiles, three- or four-wheeled buggies, general-purpose machines, and the like. [Explanation of symbols]

[0060] 1 Input gear (input member) 2 Clutch housing 3 Output shaft (output member) 4 Clutch parts 4a First clutch member 4b Second clutch member 5 Pressure member 6 Drive side clutch plate 7 Driven side clutch plate 9 Centrifugal clutch means 10 Weight member 10a First slope surface 10b Second inclined surface 11 Retaining member 12 Pressure welding member 12a First slope surface 12b Second slope surface 14 Weight member 14a Spherical member (contact part) 15 Pressure welding parts 15a First slope surface 15b Second slope surface 16 Weight member 16a, 16b Rolling members (contact parts) K power transmission device K1 Weight member side cam surface K2 Cam surface on pressure contact member side

Claims

1. a clutch member that rotates together with an input member that rotates by a driving force of a driving source, that is housed in a clutch housing that holds a plurality of driving side clutch plates, and that is connected to an output member that can rotate a wheel; a pressure member that is provided so as to be capable of approaching or separating from the clutch member and that is capable of pressing a plurality of driven-side clutch plates that are alternately arranged with the driving-side clutch plates and the plurality of driving-side clutch plates; a centrifugal clutch means having a plurality of weight members movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying rotation of the clutch housing, and a pressing member provided to be able to come into contact with the weight members and moving in a direction to press the driving side clutch plate and the driven side clutch plate together as the weight members move from the inner diameter side position to the outer diameter side position, the centrifugal clutch means pressing the driving side clutch plate and the driven side clutch plate together when the weight members are at the outer diameter side position, thereby enabling the driving force of the driving source to be transmitted to the wheels, and releasing the pressing force between the driving side clutch plate and the driven side clutch plate when the weight members are at the inner diameter side position, thereby interrupting the transmission of the driving force of the driving source to the wheels, the weight member is configured to press the driving side clutch plate and the driven side clutch plate together via the pressing member during a process in which the weight member moves from the inner diameter side position to the outer diameter side position, The pressing member is A circular main body portion; a plurality of protrusions protruding from the main body in the axial direction of the output member and aligned in the circumferential direction of the main body, the number of the plurality of protrusions is an integer multiple of the number of the plurality of weight members, A power transmission device, wherein the plurality of protrusions are disposed spaced apart from one another in the circumferential direction.

2. The plurality of protruding portions include a first protruding portion and a second protruding portion adjacent to each other in the circumferential direction, 2. The power transmission device according to claim 1, wherein, when viewed in the axial direction of the output member, a portion of each of both ends of the first convex portion extending in the radial direction in the circumferential direction and a portion of each of both ends of the second convex portion extending in the radial direction in the circumferential direction are parallel to each other.

3. The pressure contact member has a protrusion protruding radially outward from an outer circumferential edge of the main body, The power transmission device according to claim 1 , wherein, when viewed in the axial direction of the output member, a straight line passing through a center of the main body portion and a center of the protrusion in the circumferential direction does not overlap with the convex portion.

4. The main body portion has a flat surface formed between adjacent ones of the protruding portions, 2. The power transmission device according to claim 1, wherein, when viewed in the axial direction of the output member, a circumferential length of a radially outer portion of the plane is longer than a circumferential length of a radially inner portion of the plane.

5. The power transmission device according to claim 4 , wherein a length in the circumferential direction of the plane gradually increases from the radially inner side toward the radially outer side.

Images