Power transmission device

Abstract

To provide a power transmission device capable of biasing a weight member from an outer diameter side position toward an inner diameter side position with accuracy, and capable of stably moving the weight member according to centrifugal force.SOLUTION: Centrifugal clutch means 9 is configured to comprise a holding member 11, a pressure-contact member 12, and biasing members 16 that bias a weight member 10 from an outer diameter side position toward an inner diameter side position. The weight members 10 are accommodated in a plurality of accommodation parts 11a formed in a circumferential direction of the holding member 11, and are movable in a radial direction. The biasing members 16 are arranged in the circumferential direction between an inner wall surface 11aa of the accommodation part 11a and the weight member 10, and bias the weight member 10 from the outer diameter side position toward the inner diameter side position.SELECTED DRAWING: Figure 17

Description

Technical Field

[0001] The present invention relates to a power transmission device capable of arbitrarily transmitting or blocking the rotational force of an input member to an output member.

Background Art

[0002] Generally, a power transmission device equipped in a motorcycle is for arbitrarily transmitting or blocking the driving force of an engine to a transmission and drive wheels. It has an input member connected to the engine side, an output member connected to the transmission and drive wheel sides, a clutch member connected to the output member, and a pressure member that can approach or separate from the clutch member. By bringing the pressure member close to the clutch member, the driving-side clutch plate and the driven-side clutch plate are brought into pressure contact to transmit power, and by separating the pressure member from the clutch member, the pressure contact force between the driving-side clutch plate and the driven-side clutch plate is released to block the transmission of the power.

[0003] As a conventional power transmission device, for example, as disclosed in Patent Document 1, a centrifugal clutch means is proposed that includes a weight member that can move from the inner diameter side position to the outer diameter side position of the groove portion by centrifugal force accompanying the rotation of the clutch housing, thereby bringing the driving-side clutch plate and the driven-side clutch plate into pressure contact. According to such a conventional power transmission device, when the clutch housing rotates with the driving of the engine, centrifugal force can be applied to the weight member, and the driving-side clutch plate and the driven-side clutch plate can be brought into pressure contact to transmit the driving force of the engine to the wheels.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-described conventional power transmission device, since the weight member is composed of steel balls, a relatively large movement space for the steel balls is required, and there is a risk that the device may become large-sized. For this reason, the applicant of the present application has intensively studied to reduce the size of the device by using a piece-shaped weight member having front and back surfaces. In this case, in order to return the weight member to the initial position, a configuration including a biasing member such as a spring has been considered.

[0006] According to such a configuration, when the centrifugal force associated with the rotation of the clutch housing decreases, the biasing member can smoothly move the weight member from the outer diameter side position to the inner diameter side position. However, when a plurality of weight members are arranged over the circumferential direction of the holding member and each is movable in the radial direction, there is a problem that it is difficult to accurately bias the weight member from the outer diameter side position toward the inner diameter side position by the biasing means.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a power transmission device that can accurately bias a weight member from an outer diameter side position toward an inner diameter side position and can stably move the weight member according to the centrifugal force.

Means for Solving the Problems

[0008] The power transmission device according to the present invention is a clutch member that rotates together with an input member rotated by the driving force of an engine of a vehicle and is housed in a clutch housing to which a plurality of driving-side clutch plates are attached. A plurality of driven-side clutch plates formed alternately with the driving-side clutch plates are attached, and the clutch member is connected to an output member capable of rotating a wheel of the vehicle. An operating position for bringing the driving-side clutch plate and the driven-side clutch plate into pressure contact to transmit the driving force of the engine to the wheel, and a non-operating position for releasing the pressure contact force between the driving-side clutch plate and the driven-side clutch plate to block the transmission of the driving force of the engine to the wheel. A pressure member movable between them, and a weight member movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying the rotation of the clutch housing. When the weight member is in the outer diameter side position, the driving-side clutch plate and the driven-side clutch plate are brought into pressure contact to transmit the driving force of the engine to the wheel. When the weight member is in the inner diameter side position, the pressure contact force between the driving-side clutch plate and the driven-side clutch plate is released to block the transmission of the driving force of the engine to the wheel. A centrifugal clutch means, and a power transmission device comprising: the centrifugal clutch means includes a holding member that movably holds the weight member between the inner diameter side position and the outer diameter side position, and the weight member moves from the inner diameter side position to the outer diameter side position to move in the stacking direction of the driving-side clutch plate and the driven-side clutch plate to bring the driving-side clutch plate and the driven-side clutch plate into pressure contact. A pressure contact member, and a biasing member that biases the weight member from the outer diameter side position toward the inner diameter side position. The weight member is housed in a plurality of accommodating portions formed in the circumferential direction of the holding member and is movable in the radial direction. A plurality of recesses opening in the axial direction of the output member are formed on one side surface of the weight member in the axial direction of the output member. The biasing member extends in the radial direction within the recess. The inner diameter side end of the biasing member abuts against an end wall surface formed on the inner side in the radial direction of the recess. The outer diameter side end of the biasing member abuts against the inner peripheral wall surface of the accommodating portion.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 8

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Figure 10

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Figure 13

Figure 14

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Figure 17

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Figure 21

Figure 22

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Figure 24

Figure 25

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. As shown in FIG. 21, the power transmission device K according to the present embodiment is disposed in a vehicle for arbitrarily transmitting or interrupting the driving force of the engine E to the driving wheel T side via the transmission M. As shown in FIGS. 1 to 17, a clutch housing 2 in which an input gear 1 (input member) rotated by the driving force of the engine E of the vehicle is formed, an output shaft 3 (output member) connected to the transmission M, a clutch member (first clutch member 4a and second clutch member 4b), a pressure member 5, a plurality of driving side clutch plates 6 and a plurality of driven side clutch plates 7, a centrifugal clutch means 9 having a weight member 10, and an auxiliary clutch plate 17 are provided.

[0011] The input gear 1 is rotatable about the output shaft 3 when the driving force (rotational force) transmitted from the engine E is input, and is connected to the clutch housing 2 by a rivet or the like. The clutch housing 2 is composed of a cylindrical member with an open right end side in FIGS. 2 and 3, and is connected to the input gear 1, and can rotate with the rotation of the input gear 1 by the driving force of the engine E.

[0012] Further, as shown in FIG. 4, the clutch housing 2 has a plurality of notches 2a formed in the circumferential direction, and a plurality of driving-side clutch plates 6 are fitted into these notches 2a and attached. Each of the driving-side clutch plates 6 is composed of a plate material formed in a substantially annular shape, and can rotate with the rotation of the clutch housing 2 and slide in the axial direction (left-right direction in FIGS. 2 and 3).

[0013] The clutch members (the first clutch member 4a and the second clutch member 4b) have a plurality of driven-side clutch plates 7 alternately formed with the driving-side clutch plates 6 of the clutch housing 2, and are connected to an output shaft 3 (output member) that can rotate the drive wheels T via the vehicle transmission M. The clutch members are configured by assembling two members, the first clutch member 4a and the second clutch member 4b.

[0014] The first clutch member 4a has an output shaft 3 inserted through an insertion hole formed in the center thereof (see FIGS. 5 and 6), and is configured such that gears formed with each other mesh and are connected in the rotational direction. As shown in FIGS. 5 and 6, the first clutch member 4a is formed with a gradient surface 4aa that constitutes a cam for pressing assist and a gradient surface 4ab that constitutes a cam for back torque limiter. In the figure, reference numeral 4ac indicates a boss portion in which an insertion hole for a bolt B for connecting the first clutch member 4a and the fixing member 8 is formed.

[0015] As shown in FIGS. 7 and 8, the second clutch member 4b is formed of an annular member having a flange portion 4bb, and the driven clutch plate 7 is configured to be attached to a spline fitting portion 4ba formed on the outer peripheral surface by spline fitting. As shown in FIGS. 2 and 3, a pressure member 5 is assembled to the clutch members (the first clutch member 4a and the second clutch member 4b), and a plurality of driving clutch plates 6 and driven clutch plates 7 are alternately stacked between the flange portion 5c of the pressure member 5 and the flange portion 4bb of the second clutch member 4b.

[0016] As shown in FIGS. 9 and 10, the pressure member 5 is formed of a disc-shaped member having a flange portion 5c extending over the peripheral edge, and is movable between an operating position where the driving clutch plate 6 and the driven clutch plate 7 are pressed into contact with each other to transmit the driving force of the engine E to the wheels, and a non-operating position where the pressing force between the driving clutch plate 6 and the driven clutch plate 7 is released to block the transmission of the driving force of the engine E to the wheels.

[0017] More specifically, as shown in FIGS. 7 and 8, the spline fitting portion 4ba formed on the second clutch member 4b is configured by an uneven shape integrally formed over substantially the entire circumference of the outer peripheral side surface of the second clutch member 4b. By fitting the driven clutch plate 7 into the concave groove constituting the spline fitting portion 4ba, the movement of the driven clutch plate 7 in the axial direction with respect to the second clutch member 4b is allowed while the movement in the rotational direction is restricted, and it is configured to be able to rotate together with the second clutch member 4b.

[0018] Such a driven clutch plate 7 is alternately laminated with a driving clutch plate 6, and adjacent clutch plates 6 and 7 can be brought into pressure contact or the pressure contact force can be released. That is, both clutch plates 6 and 7 allow axial sliding of the second clutch member 4b. When each clutch plate (6a, 6b, 7a, 7b) is brought into pressure contact and the clutch is turned on, 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 contact force of each clutch plate (6a, 6b, 7a, 7b) is released and the clutch is turned off, the first clutch member 4a and the second clutch member 4b no longer follow the rotation of the clutch housing 2, and the transmission of the rotational force to the output shaft 3 is stopped.

[0019] Thus, in a state where the driving clutch plate 6 and the driven clutch plate 7 are in pressure contact, the rotational force (driving force of the engine E) input to the clutch housing 2 is transmitted to the drive wheel side (transmission M) via the output shaft 3 (output member). In a state where the pressure contact between the driving clutch plate 6 and the driven clutch plate 7 is released, the transmission of the rotational force (driving force of the engine E) input to the clutch housing 2 to the output shaft 3 (output member) can be blocked.

[0020] Further, as shown in FIGS. 9 and 10, a plurality (three in this embodiment) of fitting holes 5d are formed in the pressure member 5 over the circumferential direction, and clutch springs S are fitted into the respective fitting holes 5d. As shown in FIG. 2, such a clutch spring S is housed in the fitting hole 5d and one end thereof abuts against the fixing member 8, and is biased in a direction to press the driving clutch plate 6 and the driven clutch plate 7. By operating clutch operating means (not shown), the pressure contact or release of the pressure contact between the driving clutch plate 6 and the driven clutch plate 7 can be performed.

[0021] Furthermore, in the present embodiment, as shown in FIGS. 5, 6, 9, and 10, a gradient surface 4aa and 4ab are formed on the first clutch member 4a, and gradient surfaces 5a and 5b that face these gradient surfaces 4aa and 4ab are formed on the pressure member 5. That is, the gradient surface 4aa and the gradient surface 5a are in contact with each other to form a cam for pressure contact assist, and the gradient surface 4ab and the gradient surface 5b are in contact with each other to form a cam for back torque limiter.

[0022] 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 10 is in the outer diameter side position), as shown in FIG. 20(a), a rotational force in the a direction is applied to the pressure member 5. Therefore, due to the action of the cam for pressure contact assist, a force in the c direction in the figure is generated on the pressure member 5. As a result, the pressure member 5 moves in a direction closer to the flange portion 4bb of the second clutch member 4b (the left side in FIGS. 2 and 3), and the pressure contact force between the driving side clutch plate 6 and the driven side clutch plate 7 is increased.

[0023] 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 and back torque is generated, as shown in FIG. 20(b), a rotational force in the b direction is applied to the clutch member 4. Therefore, due to the action of the cam for back torque limiter, the pressure member 5 is moved in the d direction in the figure to release the pressure contact force between the driving side clutch plate 6 and the driven side clutch plate 7. As a result, problems with the power transmission device K and the power source (engine E side) due to back torque can be avoided.

[0024] As shown in FIGS. 11 to 19, the centrifugal clutch means 9 includes a weight member 10 that is movable from an inner diameter side position (see FIG. 18) to an outer diameter side position (see FIG. 19) by the centrifugal force associated with the rotation of the clutch housing 2. When the weight member 10 is at the outer diameter side position, the driving side clutch plate 6 and the driven side clutch plate 7 are pressed against each other so that the driving force of the engine E can be transmitted to the wheels (driving wheels T). When the weight member 10 is at the inner diameter side position, the pressing force between the driving side clutch plate 6 and the driven side clutch plate 7 is released so that the transmission of the driving force of the engine E to the wheels (driving wheels T) can be blocked.

[0025] Specifically, the centrifugal clutch means 9 includes a weight member 10 composed of a piece-like member, a holding member 11 to which a support member 13 is attached, a pressing member 12, a first spherical member 14, a second spherical member 15, and a biasing member 16 composed of a coil spring. The holding member 11 and the pressing member 12 are formed with a plurality of protrusions over the circumferential direction and are fitted and attached to the notch 2a of the clutch housing 2 in the same manner as the driving side clutch plate 6. As a result, the holding member 11 and the pressing member 12 are each movable in the axial direction of the clutch housing 2 and are engaged in the rotational direction so as to be rotatable together with the clutch housing 2.

[0026] As shown in FIG. 16, the weight member 10 is composed of a piece-like member having one surface X and the other surface Y. As shown in FIGS. 16 and 17, it has a through hole 10a formed to penetrate from one surface X to the other surface Y, an insertion portion 10b formed on the other surface Y, and a groove 10c formed on one surface X. Such a weight member 10 is accommodated in the accommodation portion 11a of the holding member 11 as shown in FIGS. 18 and 19, and is held at the inner diameter side position (see FIG. 18) in a state where no centrifugal force is applied. When centrifugal force is applied, it moves outward against the biasing force of the biasing member 16 and reaches the outer diameter side position (see FIG. 19).

[0027] The holding member 11 holds the weight member 10 so as to be movable between an inner diameter side position and an outer diameter side position. As shown in Fig. 13, it is composed of an annular member, formed in a plurality in the circumferential direction, and has a housing portion 11a for housing the weight member 10, a groove shape 11b formed in the housing portion 11a, and a pressing surface 11c. Each housing portion 11a has a concave shape that matches the shape and movement range of the weight member 10, and one end of the biasing member 16 can abut against the inner peripheral wall surface 11aa thereof.

[0028] Further, a support member 13 is fixed to the surface of the holding member 11 where the housing portion 11a is formed. As shown in Fig. 14, such a support member 13 is formed with a holding portion 13a formed in the radial direction. The weight member 10 is held by the holding member 11 by the holding portion 13a matching the groove 10c of the weight member 10. That is, the weight member 10 has a groove 10c formed in the direction from the inner diameter side position to the outer diameter side position at the central position of one of its surfaces X. By matching the holding portion 13a with the groove 10c, it is held so as to be movable in the radial direction (the direction from the inner diameter side position to the outer diameter side position).

[0029] The pressing member 12 moves in the stacking direction (the right side in Figs. 2 and 3) of the driving side clutch plate 6 and the driven side clutch plate 7 when the weight member 10 moves from the inner diameter side position to the outer diameter side position, and presses the driving side clutch plate 6 and the driven side clutch plate 7 together. Specifically, as shown in Fig. 15, the pressing member 12 is composed of an annular member, has a plurality of gradient grooves 12a formed in the circumferential direction, groove shapes 12b respectively formed at the positions where the gradient grooves 12a are formed, and a pressing surface 12c.

[0030] The gradient grooves 12a are respectively formed at positions corresponding to the weight members 10, and are upwardly sloped from the inner side to the outer side. Thereby, in a state where the clutch housing 2 is stopped, the weight member 10 is held at the inner diameter side position by the biasing force of the biasing member 16, and when the clutch housing 2 rotates, a centrifugal force is applied to the weight member 10 and it moves along the upwardly sloped gradient groove 12a, so that the pressure contact member 12 moves in a direction away from the holding member 11 (that is, in a direction of pressing the driving side clutch plate 6 and the driven side clutch plate 7 together).

[0031] Thus, when the holding member 11 and the pressure contact member 12 are assembled with the weight member 10 interposed therebetween, as shown in FIGS. 11 and 12, the gradient grooves 12a are positioned corresponding to the respective weight members 10. Due to the centrifugal force, the weight member 10 moves from the inner diameter side position toward the outer diameter side position along the gradient groove 12a, so that the pressure contact member 12 moves in the direction of the arrow in FIG. 11 (right side in the figure), and the pressing surface 12c formed on the pressure contact member 12 presses the driving side clutch plate 6 and the driven side clutch plate 7 to bring them into a pressure contact state. At the same time, the holding member 11 moves in the direction opposite to the arrow in FIG. 11 (left side in the figure) by the reaction force, and the pressing surface 11c formed on the holding member 11 presses the auxiliary clutch plate 17.

[0032] As shown in FIGS. 18 and 19, the weight members 10 according to the present embodiment are respectively housed in a plurality of housing portions 11a formed over the circumferential direction of the holding member 11 and are movable in the radial direction. The biasing members 16 are arranged in plural in the circumferential direction (two by two in the present embodiment) between the inner circumferential wall surface 11aa (see FIG. 13) of the housing portion 11a and the weight member 10, and bias the weight member 10 from the outer diameter side position toward the inner diameter side position. Here, the inner circumferential wall surface 11aa of the housing portion 11a is a flat surface that abuts one end of the biasing member 16, and the biasing member 16 can be attached in a stable state.

[0033] Further, the weight member 10 according to the present embodiment is formed with a tunnel-shaped insertion portion 10b through which the biasing member 16 can be inserted while opening a surface (the other surface Y in FIG. 17) facing the holding member 11. Then, by housing the weight member 10 with the biasing member 16 inserted into the insertion portion 10b in the housing portion 11a of the holding member 11, the biasing member 16 is interposed between the inner peripheral wall surface 11aa of the housing portion 11a and the weight member 10 and attached. Note that one end of the biasing member 16 is in contact with the inner peripheral wall surface 11aa while the other end is in contact with the end wall surface 10ba of the insertion portion 10b, and the weight member 10 can be biased from the outer diameter side position toward the inner diameter side position.

[0034] The first spherical member 14 is composed of a steel ball attached to the weight member 10. As shown in FIGS. 16 and 17, a part of the first spherical member 14 protrudes from one opening 10aa (the small-diameter opening on one surface X side) of the through-hole 10a formed in the weight member 10 and contacts the rolling surface of the pressing member 12 to be rollable. Further, the second spherical member 15 is composed of a steel ball attached to the weight member 10. As shown in FIGS. 16 and 17, a part of the second spherical member 15 protrudes from the other opening 10ab (the large-diameter opening on the other surface Y side) of the through-hole 10a formed in the weight member 10 and contacts the rolling surface of the holding member 11 to be rollable.

[0035] As shown in FIG. 17, the through-hole 10a according to the present embodiment is formed in a tapered shape such that the diameter continuously increases from one opening 10aa (the small-diameter opening on one surface X side) to the other opening 10ab (the large-diameter opening on the other surface Y side). The first spherical member 14 is retained at the outer peripheral edge portion of the small-diameter opening (in the present embodiment, one opening 10aa on one surface X side) among the one opening 10aa and the other opening 10ab. That is, the first spherical member 14 and the second spherical member 15 according to the present embodiment are spherical members having different diameters corresponding to the inner diameter of the through-hole 10a (the second spherical member 15 has a larger diameter than the first spherical member 14). The small-diameter first spherical member 14 is retained at the opening edge portion on the small-diameter side of the through-hole 10a and is rollable while being in contact with the inner peripheral surface of the through-hole 10a.

[0036] On the other hand, as shown in FIGS. 11 and 12, the second spherical member 15 is retained by the rolling surface of the retaining member 11. As a result, the small-diameter first spherical member 14 is retained at the opening edge on the small-diameter side of the through-hole 10a, and the large-diameter second spherical member 15 is retained by the rolling surface of the retaining member 11 while partially protruding from the opening on the large-diameter side of the through-hole 10a. In the present embodiment, the large-diameter second spherical member 15 is assembled facing the rolling surface of the retaining member 11, but the second spherical member 15 may be assembled facing the rolling surface of the pressing member 12. In this case, the small-diameter first spherical member 14 is retained at the opening edge on the small-diameter side of the through-hole 10a, and the large-diameter second spherical member 15 is retained by the rolling surface of the pressing member 12 while partially protruding from the opening on the large-diameter side of the through-hole 10a.

[0037] However, the rolling surface of the retaining member 11 (in the present embodiment, the rolling surface of the second spherical member 15) is formed of a groove shape 11b along the moving direction of the weight member 10 (the direction connecting the inner diameter side position and the outer diameter side position) as shown in FIG. 13, and the rolling surface of the pressing member 12 (in the present embodiment, the rolling surface of the first spherical member 14) is formed of a groove shape 12b along the moving direction of the weight member 10 (the direction connecting the inner diameter side position and the outer diameter side position) as shown in FIG. 15.

[0038] Furthermore, as shown in FIGS. 16, 18, and 19, the first spherical member 14 and the second spherical member 15 according to the present embodiment are each formed of a plurality (in the present embodiment, two each of the first spherical member 14 and the second spherical member 15) extending in the circumferential direction of the retaining member 11 (the width direction of the weight member 10), and the first spherical member 14 and the second spherical member 15 can each roll in the through-hole 10a and move along the groove shapes 11b and 12b as the weight member 10 moves.

[0039] The auxiliary clutch plate 17 is an annular member with a diameter different from that of the driving-side clutch plate 6 and the driven-side clutch plate 7 (in this embodiment, a smaller diameter than the driving-side clutch plate 6 and the driven-side clutch plate 7). As shown in FIGS. 2 and 3, the output shaft 3 (output member) is inserted into and fitted in the central opening 17a thereof, and it is configured to have a pressed surface 17b facing the pressing surface 11c of the holding member 11.

[0040] When the weight member 10 is at the outer diameter side position (that is, when the driving-side clutch plate 6 and the driven-side clutch plate 7 are in a pressed state), the auxiliary clutch plate 17 is pressed by the pressing surface 11c formed on the holding member 11 and brought into pressure contact, so that the driving force of the engine E can be transmitted to the output shaft 3. Further, when the weight member 10 is at the inner diameter side position (that is, when the pressing force between the driving-side clutch plate 6 and the driven-side clutch plate 7 is in a released state), when the pressing force by the pressing surface 11c formed on the holding member 11 decreases and the pressing force is released, the transmission of the driving force of the engine E to the output shaft 3 can be blocked.

[0041] That is, when the weight member 10 moves to the outer diameter side position, the gradient groove 12a functions as a cam, and the holding member 11 and the pressing member 12 move in a direction away from each other. Thereby, the pressing surface 12c of the pressing member 12 presses the driving-side clutch plate 6 and the driven-side clutch plate 7, and the pressing surface 11c of the holding member 11 presses the pressed surface 17b of the auxiliary clutch plate 17 and brings them into pressure contact, so that the driving force of the engine E is transmitted to the drive wheel T.

[0042] Furthermore, as shown in FIGS. 5 and 6, a contact surface 4ad is formed on a part of the surface of the first clutch member 4a facing the pressure member 5. As shown in FIGS. 9 and 10, a contact surface 5e is formed on a part of the surface of the pressure member 5 facing the first clutch member 4a. In a state where the first clutch member 4a, the second clutch member 4b, and the pressure member 5 are assembled (a state where there is no transmission torque from the input gear 1 (input member) to the output shaft 3 (output member)), as shown in FIGS. 2 and 3, the contact surface 4ad and the contact surface 5e are in contact with each other.

[0043] In this way, in a state where the contact surface 4ad and the contact surface 5e are in contact with each other, when the weight member 10 of the centrifugal clutch means 9 moves from the inner diameter side position (see FIG. 22) to the intermediate position (see FIG. 23) and the transmission torque from the input gear 1 (input member) to the output shaft 3 (output member) increases, the relative movement between the first clutch member 4a and the pressure member 5 is not allowed, so the operation of the cam for pressing assistance is restricted.

[0044] Thereafter, the weight member 10 of the centrifugal clutch means 9 further moves from the intermediate position (see FIG. 23) toward the outer diameter side position (see FIG. 24), is pressed by the flange portion 4bb of the second clutch member 4b, and the driving side clutch plate 6 and the driven side clutch plate 7 are pressed together. When the pressing force of the flange portion 4bb becomes equal to or greater than the biasing force of the clutch spring S, the second clutch member 4b and the pressure member 5 are moved in the axial direction (right direction in FIGS. 2 and 3) with respect to the first clutch member 4a, and the contact surface 4ad of the first clutch member 4a and the contact surface 5e of the pressure member 5 are separated. Note that FIG. 25 shows a state where the weight member 10 is at the outer diameter side position and the pressure member 5 is at the non-operating position (clutch-off state).

[0045] Thus, when the contact surface 4ad and the contact surface 5e are separated, in the process where the weight member 10 of the centrifugal clutch means 9 moves from the inner diameter side position to the outer diameter side position and the transmission torque from the input gear 1 (input member) to the output shaft 3 (output member) increases, relative movement between the first clutch member 4a and the pressure member 5 is allowed, so the operation of the cam for pressure contact assist is allowed.

[0046] According to the power transmission device K according to this embodiment, the through hole 10a of the weight member 10 in the centrifugal clutch means 9 is formed in a tapered shape from one opening 10aa to the other opening 10ab, and the first spherical member 14 is retained at the outer peripheral edge of the smaller diameter opening among the one opening 10aa and the other opening 10ab. Therefore, the first spherical member 14 can be easily and accurately attached to the weight member 10, and the manufacturing cost can be reduced.

[0047] Further, the first spherical member 14 and the second spherical member 15 are spherical members with different diameters corresponding to the inner diameter of the through hole 10a, and are made to be rollable while being in contact with the inner peripheral surface of the through hole 10a respectively. Therefore, when the weight member 10 moves, the first spherical member 14 and the second spherical member 15 can be stably rolled, and smooth movement can be achieved. Furthermore, since the second spherical member 15 according to this embodiment is retained at the rolling surface of the holding member 11 or the pressure contact member 12, the first spherical member 14 and the second spherical member 15 can be easily retained.

[0048] Furthermore, since the rolling surface of the holding member 11 or the pressure contact member 12 is formed in a groove shape (11b, 12b) along the moving direction of the weight member 10, smoother movement of the weight member 10 can be achieved while reliably retaining the second spherical member 15 on the large diameter opening side and the first spherical member 14 on the small diameter opening side respectively.

[0049] In addition, the weight member 10 according to the present embodiment is respectively accommodated in the accommodation portions 11a formed in a plurality across the circumferential direction of the holding member 11 and is movable in the radial direction. The biasing member 16 is arranged in plural in the circumferential direction between the inner peripheral wall surface 11aa of the accommodation portion 11a and the weight member 10 and biases the weight member 10 from the outer diameter side position toward the inner diameter side position. Therefore, the weight member 10 can be accurately biased from the outer diameter side position toward the inner diameter side position, and the weight member 10 can be stably moved according to the centrifugal force.

[0050] Further, the weight member 10 according to the present embodiment is formed with an insertion portion 10b through which the biasing member 16 can be inserted while opening the surface facing the holding member 11. Therefore, the biasing member 16 can be easily assembled to the weight member 10. Furthermore, the weight member 10 according to the present embodiment is formed with a groove 10c in the direction from the inner diameter side position toward the outer diameter side position, and the holding member 11 (specifically, the support member 13 fixed and integrated with the holding member 11) is formed with a holding portion 13a that holds the weight member 10 in conformity with the groove 10c. Therefore, the weight member 10 can be stably moved.

[0051] Furthermore, the centrifugal clutch means 9 according to the present embodiment includes a first spherical member 14 that protrudes partially from one opening 10aa of the through hole 10a formed in the weight member 10 and is in contact with and rollable on the rolling surface (groove shape 12b) of the pressure contact member 12, and a second spherical member 15 that protrudes partially from the other opening 10ab of the through hole 10a formed in the weight member 10 and is in contact with and rollable on the rolling surface (groove shape 11b) of the holding member 11. Therefore, the weight member 10 can be moved more stably.

[0052] In particular, the holding member 11 or the pressing member 12 has a groove shape (11b, 12b) along the moving direction of the weight member 10, and since the groove shape (11b, 12b) serves as the rolling surface of the first spherical member 14 or the second spherical member 15, the movement of the weight member 10 can be made smoother. Further, since a plurality of the first spherical members 14 and the second spherical members 15 according to the present embodiment are formed across the circumferential direction of the holding member 11 (the width direction of the weight member 10), more stable movement of the weight member 10 can be achieved.

[0053] As described above, the present embodiment has been described, but the present invention is not limited thereto. For example, it may not have the cams for pressing assist (the gradient surfaces 4aa and 5a) and the cams for back torque limiter (the gradient surfaces 4ab and 5b), or may not have the auxiliary clutch plate 17. Further, in the present embodiment, the through-hole 10a is formed in a tapered shape, but it may be an insertion hole having the same diameter from one opening to the other opening, and the first spherical member 14 and the second spherical member 15 may be caulked or the like to be prevented from coming off by other retaining means and methods.

[0054] Furthermore, in the present embodiment, in a state where the first clutch member 4a, the second clutch member 4b, and the pressure member 5 are assembled (a state where there is no transmission torque from the input gear 1 (input member) to the output shaft 3 (output member)), the contact surface 4ad and the contact surface 5e are in contact with each other, but they may not have these contact surfaces 4ad and 5e and may be in a separated state. The power transmission device of the present invention can be applied to various multi-plate clutch type power transmission devices such as motorcycles, automobiles, three- or four-wheel buggies, or general-purpose machines.

Industrial Applicability

[0055] The centrifugal clutch means includes a holding member that holds a weight member so as to be movable between an inner diameter side position and an outer diameter side position, a pressing member that moves in the stacking direction of the driving clutch plate and the driven clutch plate when the weight member moves from the inner diameter side position to the outer diameter side position to press the driving clutch plate and the driven clutch plate together, and a biasing member that biases the weight member from the outer diameter side position toward the inner diameter side position. The weight member is respectively housed in a plurality of housing portions formed over the circumferential direction of the holding member so as to be movable in the radial direction, and the biasing member is arranged in plural in the circumferential direction between the inner peripheral wall surface of the housing portion and the weight member to bias the weight member from the outer diameter side position toward the inner diameter side position. As long as it is a power transmission device, it can be applied to those having different external shapes or those to which other functions are added, etc.

Explanation of reference numerals

[0056] 1 Input gear (input member) 2 Clutch housing 2a Notch 3 Output shaft (output member) 4a First clutch member 4aa Gradient surface (cam for pressing assist) 4ab Gradient surface (cam for back torque limiter) 4ac Boss portion 4ad Contact surface 4b Second clutch member 4ba Spline fitting portion 4bb Flange portion 5 Pressure member 5a Gradient surface (cam for pressing assist) 5b Gradient surface (cam for back torque limiter) 5c Flange portion 5d Insertion hole 5e Contact surface 6 Driving clutch plate 7 Driven clutch plate 8 Fixing member 9 Centrifugal clutch means 10 Weight member 10a Through hole 10aa One opening 10ab The other opening 10b Insertion part 10ba End wall surface 10c Groove 11 Holding member 11a Accommodation part 11aa Inner peripheral wall surface 11b Groove shape 11c Pressing surface 12 Pressure contact member 12a Taper groove 12b Groove shape 12c Pressing surface 13 Support member 13a Holding part 14 First spherical member 15 Second spherical member 16 Biasing member 17 Auxiliary clutch plate 17a Central opening 17b Surface to be pressed S Clutch spring

Claims

1. A clutch member housed in a clutch housing that rotates together with an input member rotated by the driving force of an engine of a vehicle and to which a plurality of driving-side clutch plates are attached, the clutch member being connected to an output member capable of rotating a wheel of the vehicle, An operating position where the driving-side clutch plate and a driven-side clutch plate alternately arranged with the driving-side clutch plate are pressed against each other to transmit the driving force of the engine to the wheel, and a non-operating position where the pressing force between the driving-side clutch plate and the driven-side clutch plate is released to block the transmission of the driving force of the engine to the wheel, and a pressure member movable between the two positions, Centrifugal clutch means including a weight member movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying the rotation of the clutch housing, wherein when the weight member is at the outer diameter side position, the driving-side clutch plate and the driven-side clutch plate are pressed against each other to transmit the driving force of the engine to the wheel, and when the weight member is at the inner diameter side position, the pressing force between the driving-side clutch plate and the driven-side clutch plate is released to block the transmission of the driving force of the engine to the wheel, A power transmission device comprising: The centrifugal clutch means includes: A holding member that movably holds the weight member between the inner diameter side position and the outer diameter side position, A pressing member that moves in the stacking direction of the driving-side clutch plate and the driven-side clutch plate when the weight member moves from the inner diameter side position to the outer diameter side position to press the driving-side clutch plate and the driven-side clutch plate against each other, A biasing member that biases the weight member from the outer diameter side position toward the inner diameter side position, and has, The pressing member is located on the opposite side of the holding member across the weight member in the axial direction of the output member and between the weight member and the driving-side clutch plate and the driven-side clutch plate, The pressing member is: An annular main body portion, A plurality of convex portions that project from the main body portion in the axial direction so as to approach the weight member from the inner diameter side to the outer diameter side, contact the weight member, and are arranged in the circumferential direction of the main body portion, A power transmission device in which, when the weight member is in the inner diameter side position, the convex portion and the weight member overlap when viewed in the radial direction of the output member.

2. The weight member is, A main body in which a through hole penetrating in the axial direction is formed; A spherical member disposed in the through hole, partially protruding from the opening of the through hole, and contacting the convex portion; and The power transmission device according to claim 1, wherein the convex portion and the main body overlap when viewed in the radial direction of the output member in a state where the weight member is at the inner diameter side position.

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