Power transmission device

Abstract

To provide a power transmission device that makes it possible to press drive-side clutch plates and driven-side clutch plates against each other to transmit a rotational force on the wheel side to the engine side to apply an engine brake, and that makes it possible to stably perform power transmission when a weight member moves to a radially outer position and a pressure member moves to an active position.SOLUTION: A clutch member includes a first clutch member 4a, a second clutch member 4b, a back-torque transmitting cam, and a torque transmission unit that may transmit a rotational force transmitted to the second clutch member 4b to the first clutch member 4a not via the back-torque transmitting cam, where the torque transmission unit is located radially inside drive-side clutch plates 6 and driven-side clutch plates 7.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Generally, a power transmission device equipped on a motorcycle is used to freely transmit or cut off the driving force of the engine to the transmission and drive wheels, and has an input member connected to the engine, an output member connected to the transmission and drive wheels, a clutch member connected to the output member, and a pressure member that can be moved toward or away from the clutch member.By bringing the pressure member toward the clutch member, the drive side clutch plate and the driven side clutch plate are pressed together to transmit power, and by moving the pressure member away from the clutch member, the pressure force between the drive side clutch plate and the driven side clutch plate is released, thereby cutting off the transmission of power.

[0003] A conventional power transmission device, as disclosed in Patent Document 1, for example, has been proposed, which includes a weight member that can press the driving clutch plate and the driven clutch plate together by moving from an inner diameter side position to an outer diameter side position of the groove due to centrifugal force caused by rotation of the clutch housing. In this conventional power transmission device, when the engine is driven, the clutch housing rotates, which applies centrifugal force to the weight member, causing the driving clutch plate and the driven clutch plate to press together, thereby transmitting the driving force of the engine to the wheels.

[0004] Furthermore, conventional power transmission devices are equipped with a release spring that is compressed as the interlocking member moves and the pressure member moves from the inoperative position toward the operative position, and that is capable of applying a biasing force while allowing the interlocking member and the pressure member to move until the drive side clutch plates and the driven side clutch plates reach an engaged state before they are pressed together, and a clutch spring that is compressed as the interlocking member moves after the drive side clutch plates and the driven side clutch plates reach an engaged state, and that is capable of applying a pressing force between the drive side clutch plates and the driven side clutch plates while allowing the interlocking member to move. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-155884 Summary of the Invention [Means for solving the problem]

[0006] The invention of claim 1 relates to a clutch member that rotates together with an input member that rotates by the driving force of a vehicle engine and is housed in a clutch housing to which a plurality of driving-side clutch plates are attached, the clutch member having a plurality of driven-side clutch plates attached thereto and arranged alternately with the driving-side clutch plates of the clutch housing and connected to an output member that can rotate wheels of the vehicle; and a pressure section that is movable between an operating position where the driving-side clutch plates and the driven-side clutch plates are brought into pressure contact with each other to make it possible to transmit the driving force of the engine to the wheels, and a non-operating position where the pressure contact force between the driving-side clutch plates and the driven-side clutch plates is released to cut off the transmission of the driving force of the engine to the wheels. a pressure member provided on the output member and configured to move the pressure member in a direction to release the pressure contact force between the drive-side clutch plate and the driven-side clutch plate; a bearing interposed between the actuating member and the pressure member; and a bearing holding member that holds the bearing. The bearing holding member has an engaging portion that engages with the clutch member, and the clutch member has a sloped surface that constitutes a pressure contact assist cam that increases the pressure contact force between the drive-side clutch plate and the driven-side clutch plate when the rotational force input to the input member is in a state that can be transmitted to the output member, and the engaging portion overlaps with the sloped surface when viewed from the radial direction of the output member. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an external view showing a power transmission device according to an embodiment of the present invention; [Figure 2] FIG. 3 is a vertical cross-sectional view showing the internal configuration of the power transmission device. [Figure 3] FIG. 2 is a schematic diagram showing a drive-side clutch plate, a driven-side clutch plate, a back torque transmission cam, and the like in the power transmission device; [Figure 4] FIG. 4 is a perspective view showing a casing portion of a clutch housing in the power transmission device. [Figure 5] FIG. 4 is a perspective view showing a cover portion of a clutch housing in the power transmission device. [Figure 6]FIG. 3 is a three-view diagram showing a first clutch member in the power transmission device. [Figure 7] FIG. 3 is a three-view diagram showing a second clutch member in the power transmission device. [Figure 8] Three-view diagram showing a pressure member in the power transmission device [Figure 9] FIG. 10 is a perspective view showing a state before the first clutch member, the second clutch member, the pressure member, and the bearing holding member are assembled in the power transmission device; [Figure 10] FIG. 10 is a perspective view showing a state before the first clutch member, the second clutch member, the pressure member, and the bearing holding member are assembled in the power transmission device; [Figure 11] FIG. 10 is a perspective view showing the state after the first clutch member, the second clutch member, the pressure member, and the bearing holding member in the power transmission device are assembled. [Figure 12] 3A and 3B are three-view diagrams showing a bearing holding member in the power transmission device; [Figure 13] FIG. 10 is a schematic diagram illustrating the function of a pressure-contact assist cam in the power transmission device; [Figure 14] FIG. 10 is a schematic diagram illustrating the operation of a back torque limiter cam in the power transmission device. [Figure 15] FIG. 10 is a plan view showing a state in which the first clutch member and the second clutch member are assembled in the power transmission device, and shows a state in which one side surface of the protrusion and the first contact surface (torque transmission portion) are in contact with each other. [Figure 16] FIG. 10 is a plan view showing a state in which the first clutch member and the second clutch member are assembled in the power transmission device, and showing a state in which the other side surface of the protrusion and the second contact surface (movement amount limiting portion) are in contact with each other. [Figure 17] FIG. 10 is a schematic diagram illustrating the operation of a back torque transmission cam in the power transmission device, showing a state before the back torque transmission cam is activated. [Figure 18] FIG. 10 is a diagram for explaining the operation of the back torque transmission cam in the power transmission device, and is a schematic diagram showing a state after the back torque transmission cam has been activated. [Figure 19]FIG. 10 is a schematic diagram illustrating a state in which a buffer member is accommodated in an accommodating recess in a power transmission device according to another embodiment of the present invention; [Figure 20] FIG. 10 is a schematic diagram for explaining how the release spring in the power transmission device applies a biasing force to both the bearing holding member and the pressure member. [Figure 21] Three-view diagram showing the release spring in the power transmission device [Figure 22] Graph showing the movement amount and pressing load of the interlocking member in the power transmission device [Figure 23] Graph showing the movement amount and pressing load of the interlocking member in the power transmission device according to another embodiment of the present invention. [Figure 24] FIG. 10 is a vertical cross-sectional view showing a power transmission device according to another embodiment of the present invention. [Figure 25] FIG. 10 is a vertical cross-sectional view showing a power transmission device according to another embodiment of the present invention. [Figure 26] FIG. 10 is a vertical cross-sectional view showing a power transmission device according to another embodiment of the present invention. [Figure 27] FIG. 10 is a longitudinal cross-sectional view showing a power transmission device according to another embodiment of the present invention (having a buffer member 12′ and a tension-type operating member 10″); [Figure 28] 1A and 1B are a plan view and a side view showing a buffer member in the power transmission device; [Figure 29] FIG. 4 is a perspective view showing a buffer member in the power transmission device; [Figure 30] FIG. 1 is a longitudinal cross-sectional view showing a power transmission device according to another embodiment of the present invention (having a buffer member 12 and a tension-type operating member 10 ″); [Figure 31] FIG. 10 is a longitudinal cross-sectional view showing a power transmission device according to another embodiment of the present invention (in which a back torque transmission cam is disposed on the outer edge of the first clutch member 4a). [Figure 32] FIG. 10 is a longitudinal cross-sectional view showing a power transmission device according to another embodiment of the present invention (in which a back torque transmission cam is disposed on the outer edge of the first clutch member 4a and a buffer member made of a disc spring is disposed). [Figure 33]FIG. 10 is a longitudinal cross-sectional view showing a power transmission device according to another embodiment of the present invention (in which a back torque transmission cam is disposed on the outer edge of the first clutch member 4a and a buffer member made of a wave spring is disposed). [Figure 34] Graph showing the movement amount and pressing load of an interlocking member in a conventional power transmission device DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 to 12, the power transmission device according to this embodiment is installed in a vehicle such as a motorcycle to transmit or interrupt engine driving force to the transmission or drive wheels. As shown in FIGS. 1 to 12, the power transmission device is primarily comprised of a clutch housing 2 having an input gear 1 (input member) formed therein that rotates with the driving force of the vehicle engine, clutch members (first clutch member 4a and second clutch member 4b), a pressure member 5 attached to the right side of the clutch members (first clutch member 4a and second clutch member 4b) in FIG. 2, a plurality of driving-side clutch plates 6 and a plurality of driven-side clutch plates 7, a weight member 8 made of steel ball members that can move (roll) radially within the clutch housing 2, an interlocking member 9, and an operating member 10 that can be operated manually or by an actuator (not shown). In the drawings, the symbol S denotes a spring damper, the symbol B1 denotes a roller bearing, and the symbols B2 and B3 denote thrust bearings.

[0009] The input gear 1 is rotatable around the output shaft 3 when a driving force (rotational force) transmitted from the engine is input, and is connected to the clutch housing 2 by a rivet R or the like. The clutch housing 2 is made of a cylindrical member with an opening on the right end side in FIG. 2 and is configured to have a housing part 2a connected to the input gear 1 and a cover part 2b attached to close the opening of the housing part 2a, so that it can rotate together with the rotation of the input gear 1 by the driving force of the engine.

[0010] 4, the casing portion 2a of the clutch housing 2 has a plurality of notches 2aa formed in the circumferential direction, and a plurality of drive-side clutch plates 6 are fitted into these notches 2aa and attached. Each of these drive-side clutch plates 6 is made of a plate material formed in a substantially annular shape, and is configured to rotate together with the rotation of the clutch housing 2 and to be able to slide in the axial direction (left and right direction in FIG. 2).

[0011] Furthermore, as shown in Fig. 5, a plurality of grooves 2ba extending in the radial direction of the cover portion 2b are formed on the bottom surface of the cover portion 2b of the clutch housing 2. A weight member 8 is disposed in each of the grooves 2ba, and the weight member 8 is set to be in an inner diameter side position (the position shown in Fig. 2) when the clutch housing 2 is stopped (the engine is stopped or idling) or rotating at a low speed, and to be in an outer diameter side position when the clutch housing 2 is rotating at a high speed.

[0012] The clutch members (first clutch member 4a and second clutch member 4b) are attached with a plurality of driven clutch plates 7 formed alternately with the driving clutch plates 6 of the clutch housing 2, and are connected to an output shaft 3 (output member) that can rotate the wheels of the vehicle, and are formed by assembling two members, the first clutch member 4a and the second clutch member 4b.

[0013] As shown in Fig. 6, the first clutch member 4a is made of a disk-shaped member with a flange surface 4ac formed around its periphery, and the output shaft 3 is inserted into an insertion hole 4ad (see Figs. 2 and 6) formed in the center thereof, so that the gears formed therein mesh with each other to couple in the direction of rotation. As shown in Figs. 6, 9 and 10, the first clutch member 4a is formed with an inclined surface 4aa that constitutes a pressure-contact assist cam and an inclined surface 4ab that constitutes a back torque limiter cam.

[0014] As shown in Fig. 7, the second clutch member 4b is made of an annular member, and is configured so that driven-side clutch plates 7 are attached by spline fitting to spline fitting portions 4ba (see Figs. 2 and 7) formed on the outer circumferential surface. Then, as shown in Figs. 9 to 11, a pressure member 5 is assembled to the clutch members (first clutch member 4a and second clutch member 4b), and a plurality of driving-side clutch plates 6 and driven-side clutch plates 7 are attached in an alternately stacked state between a flange surface 5c (see Figs. 2 and 8) of the pressure member 5 and a flange surface 4ac (see Figs. 2 and 6) of the first clutch member 4a.

[0015] As shown in Figure 8, the pressure member 5 is a disk-shaped member with a flange surface 5c formed around its periphery, and is movable between an operating position where the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together to enable the transmission of the engine's driving force to the wheels, and a non-operating position (see Figure 2) where the pressure between the driving side clutch plate 6 and the driven side clutch plate 7 is released to block the transmission of the engine's driving force to the wheels.

[0016] More specifically, as shown in Figures 7, 9 and 10, the spline fitting portion 4ba formed on the second clutch member 4b is configured as an uneven shape formed integrally over almost the entire circumference of the outer circumferential side surface of the second clutch member 4b, and the driven-side clutch plate 7 is fitted into the groove that constitutes the spline fitting portion 4ba, thereby allowing axial movement of the driven-side clutch plate 7 relative to the second clutch member 4b while restricting movement in the rotational direction, so that the driven-side clutch plate 7 can rotate together with the second clutch member 4b.

[0017] The driven-side clutch plates 7 are stacked alternately with the driving-side clutch plates 6, so that adjacent clutch plates 6, 7 can be pressed against each other or released from the pressing force. That is, both clutch plates 6, 7 are allowed to slide in the axial direction of the second clutch member 4b, and when the pressure member 5 moves to the left in Fig. 2 and its flange surface 5c and the flange surface 4ac of the first clutch member 4a approach each other, both clutch plates 6, 7 are pressed against each other, 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. When the pressure member 5 moves to the right in Fig. 2 and its flange surface 5c and the flange surface 4ac of the first clutch member 4a move away from each other, the pressing force of both clutch plates 6, 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, so that the rotational force is no longer transmitted to the output shaft 3.

[0018] When the drive side clutch plates 6 and the driven side clutch plates 7 are pressed together, the rotational force (engine driving force) input to the clutch housing 2 is transmitted to the wheel side via the output shaft 3 (output member), and when the pressure contact between the drive side clutch plates 6 and the driven side clutch plates 7 is released, the rotational force (engine driving force) input to the clutch housing 2 is blocked from being transmitted to the output shaft 3 (output member).

[0019] 6, 8, 9, and 10, the first clutch member 4a is formed with inclined surfaces 4aa and 4ab, and the pressure member 5 is formed with inclined surfaces 5a and 5b facing the inclined surfaces 4aa and 4ab. That is, the inclined surfaces 4aa and 5a come into contact with each other to form a pressure-assist cam, and the inclined surfaces 4ab and 5b come into contact with each other to form a back torque limiter cam.

[0020] Then, when the engine speed increases and the rotational force input to the input gear 1 and the clutch housing 2 can be transmitted to the output shaft 3 via the first clutch member 4a and the second clutch member 4b (the weight member 8 is in the outer diameter side position), as shown in Fig. 13, a rotational force in the direction a is applied to the pressure member 5, and a force in the direction c in the figure is generated on the pressure member 5 by the action of the pressure contact assist cam. As a result, the pressure member 5 moves in a direction (left side in Fig. 2) where its flange surface 5c comes closer to the flange surface 4ac of the first clutch member 4a, thereby increasing the pressing force between the driving side clutch plate 6 and the driven side clutch plate 7.

[0021] On the other hand, when the rotation of the output shaft 3 exceeds the rotation speed of the input gear 1 and the clutch housing 2 while the vehicle is running, and back torque is generated in the direction b in Figure 14, the back torque limiter cam acts to move the pressure member 5 in the direction d in the figure, thereby releasing the pressure contact force between the drive-side clutch plate 6 and the driven-side clutch plate 7. This makes it possible to avoid problems with the power transmission device and power source (engine side) due to back torque.

[0022] The weight member 8 is disposed in a groove 2ba extending radially in the clutch housing 2 (cover portion 2b in this embodiment), and is capable of pressing the driving-side clutch plate 6 and the driven-side clutch plate 7 together by moving from an inner diameter side position (see FIG. 2) of the groove 2ba to an outer diameter side position by centrifugal force generated by rotation of the clutch housing 2. That is, the rolling surface (bottom surface) of the weight member 8 in the groove 2ba is inclined upward from the inner diameter side position to the outer diameter side position, and when the clutch housing 2 is stationary, the weight member 8 is held in the inner diameter side position by the biasing force of the release spring m, and when the clutch housing 2 rotates, centrifugal force is applied to the weight member 8, causing it to move along the upward gradient, and when the clutch housing 2 reaches a predetermined rotation speed, it is moved to the outer diameter side position.

[0023] The interlocking member 9 is made up of an annular member disposed inside the clutch housing 2 (cover member 2b), and is fitted into a groove formed on the inner peripheral surface of the cover member 2b to be connected thereto, so that it can rotate together with the clutch housing 2 and can move left and right in Fig. 2. As the weight member 8 moves from its inner diameter side position to its outer diameter side position, the interlocking member 9 moves leftward in Fig. 2 against the biasing forces of the clutch spring 11 and the release spring m, and presses the pressure member 5 to move it from its inoperative position to its operative position.

[0024] The actuating member 10 is a member that can be operated manually or by an actuator (see FIG. 2), and is capable of moving the pressure member 5 in a direction (to the right in FIG. 2) that releases the pressing force between the drive-side clutch plates 6 and the driven-side clutch plates 7. During a gear shift operation, for example, the actuating member 10 moves to the right in FIG. 2 by operating a clutch pedal or clutch lever equipped on the vehicle or by operating an actuator, and comes into contact with the pressure member 5 via the bearing holding member C. By moving the pressure member 5 from the actuated position to the inactuated position, the pressing force between the drive-side clutch plates 6 and the driven-side clutch plates 7 is released, and the clutch is turned off (power transmission is interrupted).

[0025] As shown in Fig. 2, the bearing holding member C is connected to the operating member 10 and holds the bearing B1 interposed between the operating member 10 and the pressure member 5. As shown in Fig. 12, it is made of a cylindrical member with one open end, having an open end Ca and a top portion Cb on the opposite side from the open end Ca. The bearing B1 according to this embodiment is attached to the top portion Cb inside the bearing holding member C, and has a cylindrical portion extending from the expanded diameter portion to the open end Ca. Although a ball bearing is used for the bearing B1 according to this embodiment, other bearings such as a needle bearing may also be used.

[0026] 2 and 20, the bearing retaining member C according to this embodiment is attached by fitting its open end Ca into a recess 4d formed in the clutch member (first clutch member 4a), and is assembled by fitting (fitting) with an inner peripheral wall surface 4da of the recess 4d. The recess 4d is formed as a circular depression that follows the outline of the open end Ca and has approximately the same dimensions (strictly speaking, dimensions slightly larger than those of the open end Ca), and by fitting the bearing retaining member C into the recess 4d, it is possible to position and center it relative to the power transmission device.

[0027] When the operating member 10 moves to the right in FIG. 2 during a gear change operation, for example, by operating the clutch pedal or clutch lever of the vehicle, or by operating the actuator, the bearing holding member C interlocks and abuts against the pressure member 5, moving the pressure member 5 from the operating position to the non-operating position, thereby releasing the pressure contact force between the driving side clutch plate 6 and the driven side clutch plate 7 and turning off the clutch (cutting off the transmission of power).

[0028] The release spring m can hold the pressure member 5 in a non-operating position, and is compressed as the interlocking member 9 moves and the pressure member 5 moves from the non-operating position toward the operating position, and can apply a biasing force while allowing the interlocking member 9 and the pressure member 5 to move until they reach an engaged state before the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together (a state in which the separation distance between the driving side clutch plate 6 and the driven side clutch plate 7 becomes zero and power transmission by pressing is just about to occur).

[0029] Furthermore, as shown in FIG. 21, the release spring m according to this embodiment is made of a circular disc spring that can generate a biasing force by displacement between a central portion ma and a peripheral portion mb. As shown in FIGS. 2 and 20, the central portion ma is attached to the top portion Cb of the bearing holding member C, and the peripheral portion mb is attached to the pressure member 5. The pressure member 5 has a protruding portion 5d that protrudes in an annular shape, and the peripheral portion mb of the release spring m is engaged and attached to a ring-shaped member g (e.g., a circlip) attached to the protruding portion 5d. As a result, the release spring m according to this embodiment is attached to both the bearing holding member C and the pressure member 5, and applies a biasing force to the pressure member 5 (a biasing force in the direction indicated by reference symbol a2 in FIG. 20) and applies a biasing force to the bearing holding member C (a biasing force in the direction indicated by reference symbol a1 in the same figure), thereby transmitting the biasing force to the operating member 10.

[0030] The clutch spring 11 consists of a coil spring interposed between the interlocking member 9 and the pressure member 5, and as the interlocking member 9 moves, it presses the pressure member 5, moving the pressure member 5 in a direction that presses the driving side clutch plate 6 and the driven side clutch plate 7 together, and when the operating member 10 is operated, it can absorb the pressing force of the pressure member 5 against the interlocking member 9.

[0031] Furthermore, the clutch spring 11 according to this embodiment is configured to be compressed as the interlocking member 9 moves, even before the drive side clutch plates 6 and the driven side clutch plates 7 reach the fastened state described above, and to apply a pressure force between the drive side clutch plates 6 and the driven side clutch plates 7 while allowing the interlocking member 9 to move.

[0032] In other words, as the clutch housing 2 rotates, the weight member 8 moves from an inner diameter side position to an outer diameter side position, and when the interlocking member 9 is pressed against the weight member 8, the pressing force is transmitted to the pressure member 5 via the clutch spring 11, causing the pressure member 5 to move to the left in Figure 2 and press the drive side clutch plate 6 and the driven side clutch plate 7 together.When the operating member 10 is operated in this state, the pressing force of the operating member 10 moves the pressure member 5 to the right in the figure, but the pressing force on the interlocking member 9 is absorbed by the clutch spring 11, and the position of the interlocking member 9 (the position of the weight member 8) is maintained.

[0033] Here, the power transmission device according to this embodiment has a back torque transmission cam (cam surfaces K1, T1) that, when a rotational force is input to the first clutch member 4a via the output shaft 3 (output member), moves the second clutch member 4b to press the driving-side clutch plate 6 and the driven-side clutch plate 7 together. As shown in Figures 6, 7, 9, and 10, this back torque transmission cam is composed of cam surfaces (K1, T1) that are integrally formed with the mating surfaces (mating surfaces when combined) of the first clutch member 4a and the second clutch member 4b, respectively.

[0034] 6 and 9, the cam surface K1 is made up of a plurality of inclined surfaces formed around the entire circumference of the inner diameter side of the flange surface 4ac formed on the first clutch member 4a (the mating surface with the second clutch member 4b), and is formed on one end surface of a plurality of grooves K formed in an annular shape along the periphery of the first clutch member 4a. That is, the first clutch member 4a has a plurality of grooves K formed around its circumference, and one end surface of each groove K is made into an inclined surface, thereby constituting the cam surface K1 of the back torque transmission cam. The other end surface of each groove K forms a wall surface K2 extending in the axial direction of the first clutch member 4a.

[0035] As shown in Figures 7 and 10, the cam surface T1 is made up of a plurality of sloped surfaces formed around the entire circumference of the bottom surface of the second clutch member 4b (the mating surface with the first clutch member 4a), and is formed on one end surface of a plurality of protrusions T formed in an annular shape along the bottom surface of the second clutch member 4b. That is, the second clutch member 4b has a plurality of protrusions T formed around its circumference, and one end surface of each protrusion T is made into a sloped surface, thereby constituting the cam surface T1 of the back torque transmission cam. The other end surface of each protrusion T forms a wall surface T2 extending in the axial direction of the second clutch member 4b.

[0036] When the protrusion T is fitted into the groove K to combine the first clutch member 4a and the second clutch member 4b, the cam surface K1 and the cam surface T1 face each other to form a back torque transmission cam, and the wall surface K2 and the wall surface T2 face each other at a predetermined distance, as shown in Fig. 17. When a rotational force is input to the first clutch member 4a via the output shaft 3, the first clutch member 4a rotates relative to the second clutch member 4b, and as shown in Fig. 18, the cam action of the cam surface K1 and the cam surface T1 moves the second clutch member 4b to the right in Figs. 2 and 18 relative to the first clutch member 4a.

[0037] On the other hand, as shown in Fig. 7, the second clutch member 4b is formed with a pressing portion 4bb on an extension of the spline fitting portion 4ba, and when the second clutch member 4b moves to the right in Fig. 2, it presses the driven-side clutch plate 7, which is the leftmost one in the figure, of the driving-side clutch plates 6 and the driven-side clutch plates 7 that are attached in a stacked state, in the same direction. As a result, even when the pressure member 5 is in the inoperative position, the driving-side clutch plates 6 and the driven-side clutch plates 7 can be pressed together, and when a rotational force is input from the output shaft 3 (output member), the rotational force can be transmitted to the engine side, generating engine braking.

[0038] In particular, the back torque transmission cam according to this embodiment is configured to move the second clutch member 4b in a direction approaching the interlocking member 9 (to the right in FIG. 2) so as to maintain contact between the interlocking member 9 and the weight member 8. In other words, when the back torque transmission cam is actuated to move the second clutch member 4b toward the right in FIG. 2, the driving-side clutch plate 6 and the driven-side clutch plate 7 are brought into pressure contact with each other and the pressure member 5 is pressed in the same direction, so that the pressing force is transmitted to the interlocking member 9 via the clutch spring 11, maintaining contact between the interlocking member 9 and the weight member 8.

[0039] However, if the interlocking member 9 and the weight member 8 separate when the back torque transmission cam is activated, there may be cases where the interlocking member 9 cannot follow the movement of the weight member 8, even when the weight member 8 moves between the inner diameter side position and the outer diameter side position as the clutch housing 2 rotates. However, according to this embodiment, the interlocking member 9 and the weight member 8 can be maintained in contact with each other even when the back torque transmission cam is activated, so that the interlocking member 9 can stably follow the movement of the weight member 8.

[0040] Furthermore, the cam surfaces K1, T1 constituting the back torque transmission cam according to this embodiment are formed in plurality along the annular shape of the driven-side clutch plate 7 attached to the second clutch member 4b. In other words, the cam surfaces K1, T1 are formed along the projected shape (annular shape) of the driven-side clutch plate 7 that is pressed by the pressing portion 4bb when the back torque transmission cam is activated. This allows the pressing portion 4bb to apply a substantially uniform pressing force to the driven-side clutch plate 7 by the action of the back torque transmission cam, and enables the driving-side clutch plate 6 and the driven-side clutch plate 7 to be pressed into contact with each other more efficiently.

[0041] Furthermore, the back torque transmission cam (cam formed by cam surface K1 and cam surface T1) according to this embodiment is configured to be operable before the back torque limiter cam (cam formed by inclined surface 4ab and inclined surface 5b) operates. In other words, the clearance (gap dimension) between cam surface K1 and cam surface T1 is set smaller than the clearance (gap dimension) between inclined surface 4ab and inclined surface 5b, so that the back torque transmission cam can operate before the back torque limiter cam operates.

[0042] Furthermore, the power transmission device according to this embodiment is provided with a torque transmission section which is formed on each of the first clutch member 4a and the second clutch member 4b and which is capable of transmitting the rotational force transmitted to the second clutch member 4b to the first clutch member 4a without passing through the back torque transmission cams (cam surface K1 and cam surface T1), and a movement amount limiting section which is formed on each of the first clutch member 4a and the second clutch member 4b and which limits the movement amount of the second clutch member 4b caused by the back torque transmission cams (cam surface K1 and cam surface T1).

[0043] That is, as shown in Figures 6 and 9, the first clutch member 4a is integrally formed with a plurality of (three in this embodiment) protrusions F spaced equally around the periphery, and the second clutch member 4b is integrally formed with a protrusion G extending inward, as shown in Figures 7 and 9. When the first clutch member 4a and the second clutch member 4b are assembled, one protrusion F is sandwiched between two protrusions G, as shown in Figures 15 and 16, and one side surface F1 of the protrusion F faces the contact surface of one of the protrusions G (first contact surface G1), and the other side surface F2 of the protrusion F faces the contact surface of the other protrusion G (second contact surface G2).

[0044] Thus, one side surface F1 of the convex portion F formed on the first clutch member 4a and the first contact surface G1 of one of the protrusions G formed on the second clutch member 4b constitute a torque transmission portion according to this embodiment. That is, when the pressure member 5 moves to the operating position, the driving-side clutch plate 6 and the driven-side clutch plate 7 are pressed together, and the clutch is turned on (driving force is transmitted), the wall surface K2 of the groove portion K in the back torque transmission cam is maintained in a spaced-apart state from the wall surface T2 of the protrusion T (see FIG. 17), and the one side surface F1 of the convex portion and the first contact surface G1 of the protrusion G come into contact with each other, as shown in FIG. 15, and the rotational force of the second clutch member 4b can be received and transmitted to the first clutch member 4a.

[0045] Furthermore, the other side surface F2 of the protrusion F formed on the first clutch member 4a and the second contact surface G2 of the other protrusion G formed on the second clutch member 4b constitute a movement amount limiting portion according to this embodiment. That is, when a rotational force is input to the first clutch member 4a via the output shaft 3, the first clutch member 4a and the second clutch member 4b rotate relatively to each other, and the second clutch member 4b moves due to the cam action between the cam surface K1 of the groove K in the back torque transmission cam and the cam surface T1 of the protrusion T (see FIG. 18). When the movement amount reaches a set value, the other side surface F2 of the protrusion and the second contact surface G2 of the protrusion G come into contact with each other, as shown in FIG. 16, and the relative rotation of the second clutch member 4b with respect to the first clutch member 4a is restricted. This limits the movement amount of the second clutch member 4b when the back torque transmission cam is activated.

[0046] In this embodiment, the protrusion F is formed on the first clutch member 4a and the protrusion G is formed on the second clutch member 4b, but instead, the protrusion G may be formed on the first clutch member 4b and the protrusion F may be formed on the second clutch member 4b. In this case, one side surface F1 of the protrusion F formed on the second clutch member 4b and a first contact surface G1 of one of the protrusions G formed on the first clutch member 4a constitute a torque transmission portion according to this embodiment, and the other side surface F2 of the protrusion F formed on the second clutch member 4b and a second contact surface G2 of the other protrusion G formed on the first clutch member 4b constitute a movement amount limiting portion according to this embodiment.

[0047] Next, the operation of the back torque transmission cam in this embodiment will be described. When the engine is stopped or idling, the driving force of the engine is not transmitted to the input gear 1 or the rotation speed of the input gear 1 is low, so that the weight member 8 is in the inner diameter position and the pressure member 5 is in the non-operating position, as shown in Fig. 2. At this time, when a rotational force is input to the first clutch member 4a via the output shaft 3 (output member), the back torque transmission cam acts to move the second clutch member 4b to the right in the figure, and the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together to transmit the rotational force to the engine side.

[0048] When the vehicle starts moving after being stopped or idling, the rotational speed of the input gear 1 transitions from low to high (medium rotation range), so the weight member 8 is located between the inner diameter side position and the outer diameter side position, and the pressure member 5 is located in the actuated position. At this time, if a rotational force is input to the first clutch member 4a via the output shaft 3 (output member) by, for example, releasing the accelerator while going downhill, the back torque transmission cam acts to move the second clutch member 4b to the right in the figure, and the drive-side clutch plate 6 and the driven-side clutch plate 7 are pressed together to transmit the rotational force to the engine side.

[0049] When the vehicle starts moving, accelerates, and travels at high speeds, the rotational speed of the input gear 1 is high, so the weight member 8 is in the outer diameter position and the pressure member 5 is in the actuated position. At this time, when a rotational force is input to the first clutch member 4a via the output shaft 3 (output member) by shifting down or the like, the back torque transmission cam acts to move the second clutch member 4b to the right in the figure, and the drive-side clutch plate 6 and the driven-side clutch plate 7 are pressed together to transmit the rotational force to the engine side.

[0050] In the power transmission device according to this embodiment, the set load of the clutch spring 11 is set to be smaller than the maximum load of the release spring m. As a result, when the engine speed increases and the weight member 8 moves from the inner diameter side position to the outer diameter side position, the interlocking member 9 is pressed by the weight member 8 and moves, and in the process, the release spring m is compressed and exceeds the set load of the clutch spring 11, and therefore the release spring m and the clutch spring 11 start to compress, thereby preventing the occurrence of a dead band.

[0051] Next, the operation of the power transmission device according to this embodiment will be explained in comparison with a conventional power transmission device in which the set load of the clutch spring is set to be greater than the maximum load of the release spring. First, the operation of the conventional power transmission device will be explained using the graph in Figure 34 (a graph with the horizontal axis representing the amount of movement (mm) of the interlocking member 9 and the vertical axis representing the pressing load (N) acting on the interlocking member 9). In the graph in Figure 34, P1 represents the pressing load of the interlocking member 9 when the amount of deflection (amount of compression) of the release spring m reaches its maximum (when the maximum load of the release spring m is reached), and P2 represents the pressing load of the interlocking member 9 when the clutch spring 11 begins to deflect (when the set load of the clutch spring 11 is reached).

[0052] As the engine speed increases and the weight member 8 moves from the inner diameter side position to the outer diameter side position, the interlocking member 9 moves, and in this process, the release spring m bends while the clutch spring 11 does not bend (i.e., the interlocking member 9 and the pressure member 5 move as a unit) until the amount of movement of the interlocking member 9 reaches α1, and when the amount of movement of the interlocking member 9 reaches α1, the pressing load (N) increases from P1 to P2, but the interlocking member 9 no longer moves, and the dead zone is reached.

[0053] When the pressing load (N) reaches P2 (set load of clutch spring 11) from such a state, clutch spring 11 begins to bend, and the pressing load (N) increases as interlocking member 9 moves. Therefore, until the pressing load (N) reaches P2 from P1, interlocking member 12 and pressure member 5 are stopped, and after reaching P2, compression of clutch spring 11 begins, and the clutch plates (drive-side clutch plates 6 and driven-side clutch plates 7) are pressed together to transmit power, which causes an abrupt feeling when power is transmitted.

[0054] In contrast to this, in this embodiment, the set load P2 of the clutch spring 11 is set to be smaller than the maximum load P1 of the release spring m, so as the interlocking member 9 moves, the release spring m is compressed and bent, and when the amount of movement of the interlocking member 9 reaches α2, the set load P2 of the clutch spring 11 is reached and the clutch spring 11 begins to compress (bend). After that, when the amount of movement of the interlocking member 9 reaches α1, the release spring m reaches the maximum load P1 and no longer compresses (bends), while the clutch spring 11 is compressed and bent, and the interlocking member 9 continues to move.

[0055] That is, according to this graph, in the process in which the interlocking member 9 moves as the engine speed increases and the weight member 8 moves from the inner diameter side position to the outer diameter side position, the release spring m continues to compress (deflect) until the amount of movement of the interlocking member 9 reaches α2, and when the amount of movement of the interlocking member 9 reaches α2 and the pressing load (N) reaches the set load P2 of the clutch spring 11, the clutch spring 11 begins to deflect together with the release spring m. Thereafter, when the amount of movement of the interlocking member 9 reaches α1, the release spring m reaches the maximum load P1 and no longer deflects, while the clutch spring 11 continues to deflect (compress), and it can be seen that the interlocking member 9 continues to move.

[0056] Therefore, before the amount of movement of the interlocking member 9 reaches α1 (before the pressing load reaches P1), the release spring m bends alone until the amount of movement of the interlocking member 9 reaches α2, and both the release spring m and the clutch spring 11 bend until the amount of movement of the interlocking member 9 reaches α1, so that the interlocking member 9 moves continuously, and when the amount of movement of the interlocking member 9 reaches α1 and the pressing load reaches the maximum load P1 of the release spring, the release spring m no longer bends, while the clutch spring 11 continues to bend, allowing for continuous movement of the interlocking member 9. This reduces the conventional dead zone and allows the weight member 8 and the interlocking member 9 to move smoothly and continuously, thereby suppressing shock when the clutch is engaged and reducing a sudden feeling when power is transmitted.

[0057] Furthermore, in this embodiment, no spring or the like is provided between the first clutch member 4a and the second clutch member 4b, but for example, a buffer member 12 may be disposed between the first clutch member 4a and the second clutch member 4b. In this case, the buffer member 12 is interposed between the first clutch member 4a and the second clutch member 4b, and is compressed (the spring is deflected) in the process in which the interlocking member 9 moves and the pressure member 5 moves from the non-operating position to the operating position, thereby applying a biasing force while allowing the interlocking member 9 and the pressure member 5 to move.

[0058] More specifically, the buffer member 12 is made of a spring set to a load that is compressed before the clutch spring 11 starts to compress, and as shown in Figures 2, 3, and 19, is housed and assembled in a housing recess 4c formed on the surface where the first clutch member 4a and the second clutch member 4b face each other (specifically, the surface of the first clutch member 4a facing the second clutch member 4b).

[0059] The accommodation recess 4c is made of a groove formed in an annular shape, and the buffer member 12 is made of a disc spring formed in an annular shape that follows the shape of the groove. As shown in Fig. 19, the accommodation recess 4c is made of a groove having an inner diameter side wall surface 4ca and an outer diameter side wall surface 4cb, and the buffer member 12 made of an annular spring fits into the groove shape.

[0060] As described above, the back torque transmission cams according to this embodiment are formed in a ring shape on the surface where the first clutch member 4a and the second clutch member 4b face each other, and the accommodating recess 4c is formed concentrically at a position adjacent to the back torque transmission cams (in this embodiment, on the inner diameter side of the position where the back torque transmission cams are formed), as shown in FIG.

[0061] Such a buffer member 12 is set to a load (P3) that compresses it before the clutch spring 11 begins to compress. Therefore, as shown in Figure 23, before the movement amount of the interlocking member 9 becomes α1 (before the pressing load becomes P1), the release spring m bends alone until the movement amount of the interlocking member 9 becomes α2, and then the release spring m and the clutch spring 11 bend together until the movement amount of the interlocking member 9 becomes α3. Thereafter, the release spring m, clutch spring 11, and buffer member 12 bend together until the movement amount of the interlocking member 9 becomes α1. Therefore, as the interlocking member 9 moves continuously, when the movement amount of the interlocking member 9 becomes α1 and the pressing load reaches the maximum load P1 of the release spring (maximum load of the buffer member 12), the deflection of the release spring m and buffer member 12 stops, while the clutch spring 11 continues to bend, thereby allowing the interlocking member 9 to move continuously. Therefore, even in this case, the conventional dead zone can be reduced and the weight member 8 and the interlocking member 9 can be moved smoothly and continuously, thereby suppressing the shock when the clutch is engaged and reducing the sudden feeling when power is transmitted.

[0062] When the buffer member 12 is arranged as described above, the accommodating recess 4c is formed concentrically on the inner diameter side of the position where the back torque transmission cam is formed, but it may also be formed concentrically on the outer diameter side of the position where the back torque transmission cam is formed.In this case, as shown in Figure 24, the buffer member 12 may be configured to apply a biasing force to the portion (disc pack) where the driving side clutch plates 6 and the driven side clutch plates 7 are stacked in a direction that presses the driving side clutch plates 6 and the driven side clutch plates 7 together.

[0063] According to this embodiment, the set load of the clutch spring 11 is set to be smaller than the maximum load of the release spring m, so that the release spring m and the clutch spring 11 are continuously compressed, causing the interlocking member 9 to move continuously, thereby preventing the creation of a dead zone, suppressing the sudden feeling during power transmission and improving operability.

[0064] Furthermore, if a buffer member 12 is provided that can apply a biasing force while allowing movement of the interlocking member 9 and the pressure member 5 by being compressed as the interlocking member 9 moves from the inoperative position to the operative position, the buffer member 12 or the clutch spring 11 will be compressed during the compression process of the release spring m, making it possible to avoid the dead zone and further suppress the sudden feeling during power transmission, thereby improving operability. Furthermore, if a buffer member 12 is provided, the buffer member 12 will be made of a spring set to a load that is compressed before the clutch spring 11 starts to compress, so that the sudden feeling during power transmission can be more reliably suppressed.

[0065] Furthermore, when the buffer member 12 is provided, the buffer member 12 is accommodated in an accommodating recess 4c formed in the surface where the first clutch member 4a and the second clutch member 4b face each other, so that it is possible to prevent the buffer member 12 from getting caught and becoming displaced when the second clutch member 4b moves relative to the first clutch member 4a. Note that although the accommodating recess 4c is formed in the surface of the first clutch member 4a facing the second clutch member 4b, it may also be formed in the surface of the second clutch member 4b facing the first clutch member 4a.

[0066] Furthermore, since the above-mentioned accommodating recess 4c is composed of a groove formed in an annular shape and the buffer member 12 is composed of a spring formed in an annular shape following the shape of the groove, the biasing force generated by the buffer member 12 can be applied approximately uniformly to the second clutch member 4b, etc., and the biasing force can be applied stably. Furthermore, since the above-mentioned back torque transmission cams are formed in a plurality of annular shapes on the surface where the first clutch member 4a and the second clutch member 4b face each other, and the accommodating recess 4c is formed concentrically at a position adjacent to the back torque transmission cams, the movement of the second clutch member 4b by the back torque transmission cams and the application of the biasing force by the buffer member 12 can be performed reliably and stably.

[0067] In addition, the bearing holding member C in this embodiment consists of a cylindrical member with one open end, and its open end Ca is fitted into a recess 4d formed in the clutch member (first clutch member 4a) and attached (attached in a spigot-jointed state), making it easy to assemble the bearing holding member C and allowing the bearing holding member C to operate stably when shifting gears.

[0068] The clutch mechanism is also configured to include a release spring m that can apply a biasing force to the pressure member 5 while allowing the interlocking member 9 and the pressure member 5 to move until the drive side clutch plate 6 and the driven side clutch plate 7 reach the fastened state before being pressed together. The release spring m is attached across both the bearing holding member C and the pressure member 5, and can apply a biasing force to the pressure member 5 and also apply a biasing force to the bearing holding member C, thereby transmitting the biasing force to the operating member 10. Therefore, the release spring m can also serve as a spring that prevents play in the speed change operating means, thereby reducing the number of parts.

[0069] Furthermore, the release spring m in this embodiment consists of a circular disc spring that can generate a spring force by displacement between the central portion ma and the peripheral portion mb, and since the central portion ma is attached to the bearing holding member C and the peripheral portion mb is attached to the pressure member 5, the spring force of the release spring m can be stably applied to both the bearing holding member C and the pressure member 5.

[0070] Furthermore, the clutch member of this embodiment has a first clutch member 4a connected to the output shaft 3 (output member), a second clutch member 4b to which a driven-side clutch plate 7 is attached, and a back torque transmission cam that can move the second clutch member 4b to press the driving-side clutch plate 6 and the driven-side clutch plate 7 together when a rotational force is input to the first clutch member 4a via the output shaft 3 (output member), and since the recess 4d is formed in the first clutch member 4a, it is possible to prevent the bearing holding member C from interfering with the movement of the second clutch member 4b by the back torque transmission cam, and it is possible to smoothly operate the bearing holding member C and move the second clutch member 4b by the back torque transmission cam.

[0071] According to the above embodiment, the back torque transmission cam can move the second clutch member 4b in a direction approaching the interlocking member 9 to maintain contact between the interlocking member 9 and the weight member 8, so that by pressing the driving side clutch plate 6 and the driven side clutch plate 7 together, the rotational force on the wheel side can be transmitted to the engine side to generate engine braking, and the weight member 8 can be operated stably when engine braking is generated.

[0072] Furthermore, the back torque transmission cam according to this embodiment is composed of cam surfaces (K1, T1) integrally formed on the first clutch member 4a and the second clutch member 4b, respectively, and the cam surfaces (K1, T1) are formed on the mating surfaces of the first clutch member 4a and the second clutch member 4b, respectively, so that the movement of the second clutch member 2b by the back torque transmission cam can be carried out reliably and smoothly.

[0073] Furthermore, the inclined surface 4aa formed on the first clutch member 4a and the inclined surface 5a formed on the pressure member 5 are opposed to each other, and a pressure-assist cam is provided for increasing the pressure contact force between the drive side clutch plate 6 and the driven side clutch plate 7 when the rotational force input to the input gear 1 (input member) can be transmitted to the output shaft 3 (output member).As a result, the pressure contact force from the pressure-assist cam can be applied in addition to the pressure contact force caused by the movement of the weight member 8 due to centrifugal force, and the drive side clutch plate 6 and the driven side clutch plate 7 can be pressed together more smoothly and reliably.

[0074] Furthermore, the back torque limiter cam is configured so that the inclined surface 4ab formed on the first clutch member 4a faces the inclined surface 5b formed on the pressure member 5, and is capable of releasing the pressure contact force between the drive side clutch plate 6 and the driven side clutch plate 7 when the rotation of the output shaft 3 (output member) exceeds the rotation speed of the input gear 1 (input member) and the clutch member (first clutch member 4a) and the pressure member 5 rotate relative to each other. Therefore, when the weight member 8 is in the outer diameter side position, it is possible to avoid excessive power being transmitted to the engine side via the input gear 1, and since the back torque transmission cam is configured to operate before the back torque limiter cam is operated, operation by the back torque transmission cam can be performed reliably.

[0075] In addition, according to this embodiment, when a rotational force is input to the first clutch member 4a via the output shaft 3 (output member), a back torque transmission cam is provided which can move the second clutch member 4b to press the driving side clutch plate 6 and the driven side clutch plate 7 together, and a torque transmission section is formed on the first clutch member 4a and the second clutch member 4b, respectively, which can transmit the rotational force transmitted to the second clutch member 4b to the first clutch member 4a without going through the back torque transmission cam (cam surface K1 and cam surface T1).Therefore, by pressing the driving side clutch plate 6 and the driven side clutch plate 7 together, the rotational force on the wheel side can be transmitted to the engine side, thereby generating engine braking, and power transmission can be stably performed when the weight member 8 moves to the outer diameter side position and the pressure member 5 moves to the operating position.

[0076] Furthermore, the first clutch member 4a and the second clutch member 4b are each provided with a movement limiting portion that limits the movement amount of the second clutch member 4b caused by the back torque transmission cam, so that the movement of the second clutch member 4b caused by the back torque transmission cam can be carried out within a set range.

[0077] Furthermore, a convex portion F is formed on either the first clutch member 4a or the second clutch member 4b, and the torque transmission portion consists of one side surface F1 of the convex portion F and a first abutment surface G1 that abuts against the one side surface F1 and can receive rotational force, and the movement amount limiting portion consists of the other side surface F2 of the convex portion F and a second abutment surface G2 that abuts against the other side surface F2 and can limit the movement amount, so that the convex portion F can function as both the torque transmission portion and the movement amount limiting portion.

[0078] While the present embodiment has been described above, the present invention is not limited to this and may be applied to a power transmission device in which a weight member 8 is movably disposed in the casing portion 2a of the clutch housing 2, as shown in Figures 25 and 26. Similar to the above embodiment, this power transmission device has a first clutch member 4a, a second clutch member 4b, and a back torque transmission cam, and is configured such that a buffer member 12 is interposed between the first clutch member 4a and the second clutch member 4b.

[0079] 25 shows an embodiment in which a buffer member 12 is attached to the surface of the first clutch member 4a that faces the second clutch member 4b, and FIG. 26 shows an embodiment in which a buffer member 12 is attached to the portion (disc pack) in the first clutch member 4a where the driving-side clutch plates 6 and the driven-side clutch plates 7 are stacked, to apply a biasing force. The bearing holding member C' is movable by the operating member 10', and the release spring m' is made up of a coil spring attached across both the bearing holding member C' and the pressure member 5.

[0080] Furthermore, instead of the buffer member 12 made of a disc spring, other elastic members may be used, and for example, as shown in Figure 27, a buffer member 12' made of a wave spring may be disposed in the accommodation recess 4c. As shown in Figures 28 and 29, such a wave spring is made of a C-shaped member having a notch 12'a in part of its annular shape, and is formed in a wave shape in the thickness direction t to generate elasticity, and is interposed between the first clutch member 4a and the second clutch member 4b, and is configured to apply a biasing force while allowing movement of the interlocking member 9 and the pressure member 5 by being compressed as the interlocking member 9 moves and the pressure member 5 moves from the inoperative position to the operative position.

[0081] In the power transmission device shown in the figure, the bearing holding member C has a plurality of communication holes Cc (three in this embodiment) formed in its side wall, so that oil supplied into the bearing holding member C can flow out via the oil flow path r. In addition, the operating member 10" is engaged with the roller bearing B1 of the bearing holding member C, and can be moved left and right in the figure by operation by the driver or by operation of the actuator, thereby moving the pressure member 5 between an operating position and a non-operating position.

[0082] On the other hand, as shown in FIG. 27, the operating member 10" according to this embodiment is of a pull type, and when operated manually or by an actuator, it moves to the right in the figure and pulls the bearing B1 in the same direction, thereby releasing the pressure contact force between the driving-side clutch plate 6 and the driven-side clutch plate 7. Note that instead of the buffer member 12 of the power transmission device shown in FIG. 27, a buffer member 12' made of a disc spring may be provided, as shown in FIG. 30.

[0083] Furthermore, as shown in Figure 31, back torque transmission cams (cam surface K1 and cam surface T1) may be disposed on the outer peripheral edges of the first clutch member 4a and the second clutch member 4b. According to this power transmission device, since the back torque transmission cams are disposed on the outer peripheral edges of the first clutch member 4a and the second clutch member 4b, the action of the cams can be increased, and the moving force (thrust) of the second clutch member 4b can be set to be large.

[0084] Although Figure 31 shows a power transmission device in which no buffer members 12, 12' are arranged, it is also possible to use a power transmission device in which a buffer member 12 made of a disc spring is arranged on the inner diameter side of the back torque transmission cam (cam surface K1 and cam surface T1) (see Figure 32), or a power transmission device in which a buffer member 12' made of a wave spring is arranged on the inner diameter side of the back torque transmission cam (cam surface K1 and cam surface T1) (see Figure 33).

[0085] In addition, in this embodiment, the bearing holding member C is made of a cylindrical member with one open end, and the open end Ca is fitted into a recess 4d formed in the clutch member (first clutch member 4a) and attached, but the bearing holding member may have a different shape, and may have an attachment structure different from the form in which it fits into a recess formed in the clutch member (so-called spigot joint).The power transmission device of the present invention can be applied to various multi-plate clutch type power transmission devices in addition to motorcycles, automobiles, three- or four-wheeled buggies, general-purpose machines, etc. [Industrial Applicability]

[0086] The present invention can be applied to power transmission devices with different external shapes or with additional functions, as long as they have the same gist as the present invention. [Explanation of symbols]

[0087] 1 Input gear (input member) 2 Clutch housing 2a Housing 2b Cover part 3 Output shaft (output member) 4a First clutch member 4aa Inclined surface (pressure-assist cam) 4ab slope surface (back torque limiter cam) 4ac flange surface 4ad insertion hole 4b Second clutch member 4ba spline fitting 4bb Pressing part 4c Recessed storage area 4d recess 4da Inner wall surface 5 Pressure member 5a Inclined surface (pressure-assist cam) 5b Inclined surface (back torque limiter cam) 5c Flange surface 6 Drive side clutch plate 7 Driven side clutch plate 8 Weight member 9 Interlocking members 10. Actuating member 11 Clutch spring 12. Cushioning material (disc spring) 12' shock absorber (wave spring) 12'a Notch C Bearing retaining member Ca open end Cb top Cc communication hole K groove K1 cam surface K2 wall T protrusion T1 cam surface T2 Wall F convex part G protrusion G1 1st contact surface G2 2nd contact surface m Release spring r Oil flow path

Claims

[Claim 1] a clutch member that rotates together with an input member that rotates by the driving force of a vehicle engine and is housed in a clutch housing to which a plurality of driving-side clutch plates are attached, the clutch member having a plurality of driven-side clutch plates that are arranged alternately with the driving-side clutch plates of the clutch housing, and is connected to an output member that can rotate wheels of the vehicle; a pressure member that is movable between an operating position where the driving side clutch plates and the driven side clutch plates are pressed together to enable transmission of the driving force of the engine to the wheels, and a non-operating position where the pressing force between the driving side clutch plates and the driven side clutch plates is released to interrupt transmission of the driving force of the engine to the wheels; an operating member provided on the output member and configured to move the pressure member in a direction to release the pressure contact force between the driving-side clutch plate and the driven-side clutch plate; a bearing interposed between the operating member and the pressure member; a bearing holding member for holding the bearing; In a power transmission device having the bearing holding member has a fitting portion that fits onto the clutch member, the clutch member has an inclined surface that constitutes a pressure-contact assist cam that increases the pressure contact force between the driving-side clutch plate and the driven-side clutch plate when the rotational force input to the input member is ready to be transmitted to the output member, When viewed from a radial direction of the output member, the fitting portion overlaps with the inclined surface.

Images