Power transmission device

Abstract

To provide a power transmission apparatus capable of preventing sudden power transmission with unintended timing caused by accidental operation of a pressing assist cam when a vehicle including centrifugal clutch means starts to move.SOLUTION: During movement of a weight member 10 of centrifugal clutch means 9 from a radially inner position to a radially outer position and a resulting increase in torque transmitted from an input gear 1 to an output shaft 3, a power transmission apparatus includes a first torque region α1, where the apparatus restricts operation of a pressing assist cam, and a second torque region α2, where the apparatus allows operation of the pressing assist cam.SELECTED DRAWING: Figure 22

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 provided in a motorcycle is for arbitrarily transmitting or blocking the driving force of an engine to a transmission and a driving wheel. It has an input member connected to the engine side, an output member connected to the transmission and driving 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 closer to the clutch member, the driving-side clutch plate and the driven-side clutch plate are pressed together to transmit power, and by separating the pressure member from the clutch member, the pressing 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 an inner diameter side position to an outer diameter side position of the groove portion by centrifugal force accompanying the rotation of the clutch housing, thereby pressing the driving-side clutch plate and the driven-side clutch plate together. According to such a conventional power transmission device, when the clutch housing rotates as the engine drives, centrifugal force can be applied to the weight member, and the driving-side clutch plate and the driven-side clutch plate can be pressed together to transmit the driving force of the engine to the wheels.

[0004] Further, according to the above conventional power transmission device, since a cam for pressing assist for increasing the pressing force between the driving-side clutch plate and the driven-side clutch plate is provided when the rotational force input to the input member can be transmitted to the output member, when the driver operates the clutch to press the driving-side clutch plate and the driven-side clutch plate together, the operating force can be reduced to enable smooth power transmission.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the above conventional power transmission device, in the process where the weight member of the centrifugal clutch means moves from the inner diameter side position to the outer diameter side position and the transmission torque from the input member to the output member increases, for example, the cam for pressure contact assist inadvertently operates in the semi-clutch region, and there is a risk that power transmission will be suddenly performed unintentionally at the time of starting the vehicle, making smooth running difficult.

[0007] The present invention has been made in view of such circumstances, and in a vehicle equipped with centrifugal clutch means, it is an object to provide a power transmission device capable of preventing the cam for pressure contact assist from inadvertently operating and power transmission from being suddenly performed at an unintended timing when the vehicle starts.

Means for Solving the Problems

[0008] The invention according to claim 1 is a clutch member accommodated 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 driven clutch plates formed alternately with the driving clutch plates are attached, and is connected to an output member capable of rotating a wheel of the vehicle. The clutch member includes a pressure member movable between an operating position in which the driving clutch plate and the driven clutch plate are pressed against each other to transmit the driving force of the engine to the wheel, and a non-operating position in which the pressing force between the driving clutch plate and the driven clutch plate is released to block the transmission of the driving force of the engine to the wheel, 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 clutch plate and the driven clutch plate are pressed against each other to transmit the driving force of the engine to the wheel, and when the weight member is in the inner diameter side position, the pressing force between the driving clutch plate and the driven clutch plate is released to block the transmission of the driving force of the engine to the wheel. The centrifugal clutch means includes a cam for pressing assist for increasing the pressing force between the driving clutch plate and the driven clutch plate. The power transmission device has a first torque region corresponding to an engine rotation speed from the engine rotation speed at which the weight member of the centrifugal clutch means is in the inner diameter side position to a predetermined engine rotation speed, and restricting the operation of the cam for pressing assist, and a second torque region corresponding to an engine rotation speed from the predetermined engine rotation speed to the engine rotation speed at which the weight member is in the outer diameter side position, and allowing the operation of the cam for pressing assist.

[0009] The invention according to claim 2 is the power transmission device according to claim 1, wherein the clutch member has a first clutch member connected to the output member and a second clutch member to which the driven-side clutch plate is attached, and the cam for pressing assist is configured such that a gradient surface formed on the first clutch member and a gradient surface formed on the pressure member face each other.

[0010] The invention according to claim 3 is the power transmission device according to claim 2, wherein in the first torque region, the first clutch member and the pressure member are in contact with each other to restrict the operation of the cam for pressing assist, and in the second torque region, the first clutch member and the pressure member are separated from each other to allow the operation of the cam for pressing assist.

[0011] The invention according to claim 4 is the power transmission device according to claim 3, wherein in the first torque region, the centrifugal clutch means moves the second clutch member to maintain the contact state between the first clutch member and the pressure member, and in the second torque region, the centrifugal clutch means moves the second clutch member and the pressure member to separate the first clutch member and the pressure member.

[0012] The invention according to claim 5 is the power transmission device according to claim 4, characterized in that it shifts from the first torque region to the second torque region during the operation process of the centrifugal clutch means. The invention according to claim 6 is the power transmission device according to claim 1, wherein in the first torque region, the clutch member and the pressure member are in contact with each other to restrict the operation of the cam for pressing assist, and in the second torque region, relative movement between the clutch member and the pressure member is allowed to allow the operation of the cam for pressing assist. The invention according to claim 7 is a clutch member accommodated 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. 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. A pressure member that can move between an operating position where 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 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. The pressure member is provided with a weight member that can move 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 pressed against each other to transmit the driving force of the engine to the wheel, and when the weight member is in 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 centrifugal clutch means, and a cam for pressing assist for increasing the pressing force between the driving-side clutch plate and the driven-side clutch plate. In a power transmission device provided with the cam for pressing assist, the operation of the cam for pressing assist is restricted when the weight member is in the inner diameter side position, and the restriction on the operation of the cam for pressing assist is released and the operation of the cam for pressing assist is allowed when the weight member is in the outer diameter side position. The invention according to claim 8 is the power transmission device according to claim 7, wherein when the weight member is in the inner diameter side position, the clutch member and the pressure member are in contact with each other to restrict the operation of the cam for pressing assist, and when the weight member is in the outer diameter side position, the clutch member and the pressure member are separated from each other to allow the operation of the cam for pressing assist. The invention according to claim 9 is a clutch member accommodated 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. 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. A pressure member that can move between an operating position where 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 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. A weight member that can move 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 pressed against each other to transmit the driving force of the engine to the wheel. When the weight member is in 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 centrifugal clutch means, and a cam for pressing assist for increasing the pressing force between the driving-side clutch plate and the driven-side clutch plate. In a state where the weight member is in the inner diameter side position, the clutch member and the pressure member are in contact with each other to restrict the operation of the cam for pressing assist. In a state where the weight member is in the outer diameter side position, relative movement between the clutch member and the pressure member is allowed to allow the operation of the cam for pressing assist. The invention according to claim 10 is the power transmission device according to claim 9, wherein the clutch member has a first clutch member connected to the output member and a second clutch member to which the driven-side clutch plate is attached. In a state where the weight member is in the inner diameter side position, the first clutch member and the pressure member are in contact with each other to restrict the operation of the cam for pressing assist.

Effects of the Invention

[0013] According to the invention of claim 1, in a torque region corresponding to engine speeds from the engine speed at which the weight member of the centrifugal clutch means is located at the inner diameter side position to a predetermined engine speed, there is a first torque region that restricts the operation of the cam for pressure contact assist, and in a torque region corresponding to engine speeds from a predetermined engine speed to the engine speed at which the weight member is located at the outer diameter side position, there is a second torque region that allows the operation of the cam for pressure contact assist. Therefore, in a vehicle equipped with centrifugal clutch means, it is possible to prevent the cam for pressure contact assist from operating inadvertently and causing sudden power transmission at an unintended timing when the vehicle starts.

[0014] According to the invention of claim 2, the clutch member has a first clutch member connected to the output member and a second clutch member to which the driven-side clutch plate is attached. Also, the cam for pressure contact assist is configured such that the gradient surface formed on the first clutch member and the gradient surface formed on the pressure member face each other. Therefore, the cam for pressure contact assist can be operated by the first clutch member and the pressure member.

[0015] According to the invention of claim 3, in the first torque region, the first clutch member and the pressure member come into contact and the operation of the cam for pressure contact assist is restricted, and in the second torque region, the first clutch member and the pressure member are separated and the operation of the cam for pressure contact assist is allowed. Therefore, it is possible to accurately and smoothly restrict the operation of the cam for pressure contact assist in the first torque region and allow the operation of the cam for pressure contact assist in the second torque region.

[0016] According to the invention of claim 4, in the first torque region, the centrifugal clutch means moves the second clutch member while maintaining the contact state between the first clutch member and the pressure member. In the second torque region, the centrifugal clutch means moves the second clutch member and the pressure member to separate the first clutch member and the pressure member. Therefore, the operation of the cam for pressing assist in the first torque region can be restricted and the operation of the cam for pressing assist in the second torque region can be allowed by the operation of the centrifugal clutch means.

[0017] According to the invention of claim 5, since it shifts from the first torque region to the second torque region during the operation process of the centrifugal clutch means, the restriction of the operation of the cam for pressing assist in the first torque region and the allowance of the operation of the cam for pressing assist in the second torque region can be performed continuously and smoothly.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 27

Mode for Carrying Out the Invention

[0019] 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 this embodiment is disposed in a vehicle and is 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, it includes a clutch housing 2 formed with an input gear 1 (input member) that rotates by the driving force of the vehicle engine E, 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.

[0020] 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 formed of a cylindrical member with an open right end side in FIGS. 2 and 3 and is connected to the input gear 1 so as to be rotatable with the rotation of the input gear 1 by the driving force of the engine E.

[0021] Further, as shown in FIG. 4, the clutch housing 2 is formed with a plurality of notches 2a extending 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 formed of a plate material formed in a substantially annular shape and is configured to rotate with the rotation of the clutch housing 2 and slide in the axial direction (left-right direction in FIGS. 2 and 3).

[0022] The clutch members (the first clutch member 4a and the second clutch member 4b) are configured such that a plurality of driven clutch plates 7 formed alternately with the drive-side clutch plate 6 of the clutch housing 2 are attached thereto, and are connected to an output shaft 3 (output member) capable of rotating a drive wheel T via a vehicle transmission M. The clutch members are constituted by assembling two members, namely the first clutch member 4a and the second clutch member 4b.

[0023] The first clutch member 4a is configured such that the output shaft 3 is inserted through an insertion hole formed at its center (see FIGS. 5 and 6), and gears formed thereon mesh with each other to be rotationally connected. As shown in FIGS. 5 and 6, such first clutch member 4a is formed with a gradient surface 4aa constituting a cam for pressure contact assist and a gradient surface 4ab constituting a cam for back torque limiter. Note that reference numeral 4ac in the figure 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.

[0024] The second clutch member 4b is composed of an annular member formed with a flange portion 4bb as shown in FIGS. 7 and 8, and is configured such that the driven clutch plate 7 is attached to a spline fitting portion 4ba formed on the outer peripheral surface by spline fitting. Then, 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 drive-side clutch plates 6 and driven clutch plates 7 are alternately stacked and attached between the flange portion 5c of the pressure member 5 and the flange portion 4bb of the second clutch member 4b.

[0025] The pressure member 5 is composed of a disk-shaped member formed with a flange portion 5c over its peripheral edge as shown in FIGS. 9 and 10, and is movable between an operating position where the drive-side clutch plate 6 and the driven clutch plate 7 are pressed into contact to enable transmission of the driving force of the engine E to the wheels, and a non-operating position where the pressing force between the drive-side clutch plate 6 and the driven clutch plate 7 is released to block transmission of the driving force of the engine E to the wheels.

[0026] 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 in the rotational direction of the driven clutch plate 7 with respect to the second clutch member 4b is restricted while allowing the axial movement, and it is configured to be able to rotate together with the second clutch member 4b.

[0027] Such a driven clutch plate 7 is alternately laminated with the 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 are allowed to slide in the axial direction 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.

[0028] 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 driving wheel side (transmission M) via the output shaft 3 (output member), and 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.

[0029] Further, as shown in FIGS. 9 and 10, the pressure member 5 has a plurality (three in this embodiment) of fitting holes 5d formed over the circumferential direction, and a clutch spring S is fitted into each of the fitting holes 5d. As shown in FIG. 2, such a clutch spring S is housed in the fitting hole 5d while one end thereof abuts against the fixing member 8, and is biased in the direction of pressing the driving-side clutch plate 6 and the driven-side clutch plate 7. Then, by operating clutch operating means (not shown), the driving-side clutch plate 6 and the driven-side clutch plate 7 can be pressed or the pressing can be released.

[0030] Furthermore, in this embodiment, as shown in FIGS. 5, 6, 9, and 10, the first clutch member 4a is formed with gradient surfaces 4aa and 4ab, and the pressure member 5 is formed with gradient surfaces 5a and 5b facing these gradient surfaces 4aa and 4ab. That is, the gradient surface 4aa and the gradient surface 5a abut against each other to form a cam for pressure contact assist, and the gradient surface 4ab and the gradient surface 5b abut against each other to form a cam for back torque limiter.

[0031] 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 at 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 in the pressure member 5. As a result, the pressure member 5 moves in the direction in which its flange portion 5c approaches the flange portion 4bb of the second clutch member 4b (the left side in FIGS. 2 and 3), so as to increase the pressing force between the driving-side clutch plate 6 and the driven-side clutch plate 7.

[0032] On one hand, when the rotation of the output shaft 3 causes a back torque that exceeds the rotational speeds of the input gear 1 and the clutch housing 2, 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 the back torque limiter, the pressure member 5 is moved in the d direction in the figure to release the pressing force between the driving-side clutch plate 6 and the driven-side clutch plate 7. This can avoid problems with the power transmission device K and the power source (engine E side) caused by the back torque.

[0033] 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 accompanying 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 together 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.

[0034] Specifically, the centrifugal clutch means 9 is composed of a weight member 10 formed 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 made of a coil spring. Note that 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.

[0035] As shown in Fig. 16, the weight member 10 is composed of a piece-shaped member having one surface X and the other surface Y. As shown in Figs. 16 and 17, it is configured to have 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 a 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).

[0036] The holding member 11 holds the weight member 10 so as to be movable between the inner diameter side position and the outer diameter side position. As shown in Fig. 13, it is composed of an annular member, and a plurality of accommodation portions 11a for accommodating the weight member 10 are formed over the circumferential direction. It is configured to have a groove shape 11b formed in the accommodation portion 11a and a pressing surface 11c. Each accommodation 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 is configured to be able to contact the inner peripheral wall surface 11aa thereof.

[0037] Further, the support member 13 is fixed to the surface of the holding member 11 where the accommodation 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. Since the holding portion 13a matches the groove 10c of the weight member 10, the weight member 10 is held by the holding member 11. 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 surface X thereof. 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).

[0038] The pressing member 12 moves in the stacking direction of the driving clutch plate 6 and the driven clutch plate 7 (the right side in FIGS. 2 and 3) when the weight member 10 moves from the inner diameter side position to the outer diameter side position, and presses the driving clutch plate 6 and the driven clutch plate 7 together. Specifically, as shown in FIG. 15, the pressing member 12 is formed of an annular member, and has a plurality of gradient grooves 12a formed over the circumferential direction, groove shapes 12b respectively formed at positions where the gradient grooves 12a are formed, and a pressing surface 12c.

[0039] The gradient grooves 12a are respectively formed at positions corresponding to the weight member 10, and have an upward gradient from the inside to the outside. 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, centrifugal force is applied to the weight member 10, and the weight member 10 moves along the upward gradient groove 12a, so that the pressing member 12 moves in a direction away from the holding member 11 (that is, a direction in which the driving clutch plate 6 and the driven clutch plate 7 are pressed together).

[0040] When the holding member 11 and the pressing 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 centrifugal force, the weight member 10 moves from the inner diameter side position to the outer diameter side position along the gradient grooves 12a, so that the pressing member 12 moves in the direction of the arrow in FIG. 11 (the right side in the figure). The pressing surface 12c formed on the pressing member 12 presses the driving clutch plate 6 and the driven clutch plate 7 to bring them into a pressed state, and the holding member 11 moves in the direction opposite to the arrow in FIG. 11 (the 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.

[0041] As shown in FIGS. 18 and 19, the weight member 10 according to the present embodiment is respectively accommodated in a plurality of accommodating portions 11a formed over the circumferential direction of the holding member 11 and is movable in the radial direction. The biasing members 16 are arranged in plural (two by two in the present embodiment) in the circumferential direction between the inner peripheral wall surface 11aa (see FIG. 13) of the accommodating 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 peripheral wall surface 11aa of the accommodating portion 11a is a flat surface that abuts against one end of the biasing member 16, and the biasing member 16 can be attached in a stable state.

[0042] 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 the surface facing the holding member 11 (the other surface Y in FIG. 17). Then, by accommodating the weight member 10 with the biasing member 16 inserted into the insertion portion 10b in the accommodating portion 11a of the holding member 11, the biasing member 16 is interposed between the inner peripheral wall surface 11aa of the accommodating portion 11a and the weight member 10 and attached. Note that one end of the biasing member 16 abuts against the inner peripheral wall surface 11aa while the other end abuts against the end wall surface 10ba of the insertion portion 10b, so that the weight member 10 can be biased from the outer diameter side position toward the inner diameter side position.

[0043] 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. 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.

[0044] As shown in Fig. 17, the through-hole 10a according to this 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 of the small-diameter opening (in this embodiment, the 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 this 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 on the small-diameter side of the through-hole 10a and is capable of rolling while being in contact with the inner peripheral surface of the through-hole 10a respectively.

[0045] On the other hand, as shown in Figs. 11 and 12, the second spherical member 15 is retained on the rolling surface of the holding 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 on the rolling surface of the holding member 11 while partially protruding from the opening on the large-diameter side of the through-hole 10a. In this embodiment, the large-diameter second spherical member 15 is assembled facing the rolling surface of the holding member 11, but the second spherical member 15 may be assembled facing the rolling surface of the pressure contact 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 on the rolling surface of the pressure contact member 12 while partially protruding from the opening on the large-diameter side of the through-hole 10a.

[0046] However, as shown in Fig. 13, the rolling surface of the holding member 11 (in this 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), and as shown in Fig. 15, the rolling surface of the pressure contact member 12 (in this 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).

[0047] 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 in a plurality (two in the present embodiment for both the first spherical member 14 and the second spherical member 15) across the circumferential direction of the holding member 11 (the width direction of the weight member 10). As the weight member 10 moves, the first spherical member 14 and the second spherical member 15 can move along the groove shapes 11b and 12b while rolling within the through-hole 10a respectively.

[0048] The auxiliary clutch plate 17 is formed of an annular member having a diameter different from that of the driving-side clutch plate 6 and the driven-side clutch plate 7 (a smaller diameter than the driving-side clutch plate 6 and the driven-side clutch plate 7 in the present embodiment). As shown in FIGS. 2 and 3, the output shaft 3 (output member) is inserted through the central opening 17a thereof and is in a fitted state, and it is configured to have a pressed surface 17b facing the pressing surface 11c of the holding member 11.

[0049] 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), when the auxiliary clutch plate 17 is pressed and brought into pressure contact by the pressing surface 11c formed on the holding member 11, the driving force of the engine E can be transmitted to the output shaft 3. Also, 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 pressure contact force is released, the transmission of the driving force of the engine E to the output shaft 3 can be blocked.

[0050] 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 pressure contact member 12 move in a direction away from each other. Thereby, the pressing surface 12c of the pressure contact 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 to bring them into pressure contact, so that the driving force of the engine E is transmitted to the drive wheel T.

[0051] According to the power transmission device K according to the present 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 prevented from coming off 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.

[0052] Further, the first spherical member 14 and the second spherical member 15 are spherical members having different diameters corresponding to the inner diameter of the through hole 10a, and are capable of rolling while being in contact with the inner peripheral surface of the through hole 10a, respectively. Therefore, the first spherical member 14 and the second spherical member 15 can be stably rolled when the weight member 10 moves, and smooth movement can be achieved. Furthermore, since the second spherical member 15 according to the present embodiment is prevented from coming off at the rolling surface of the holding member 11 or the pressing member 12, the first spherical member 14 and the second spherical member 15 can be easily prevented from coming off.

[0053] Furthermore, since the rolling surfaces of the holding member 11 or the pressing member 12 are formed in a groove shape (11b, 12b) along the moving direction of the weight member 10, it is possible to more smoothly move the weight member 10 while surely preventing the second spherical member 15 from coming off on the large-diameter opening side and the first spherical member 14 from coming off on the small-diameter opening side, respectively.

[0054] In addition, the weight members 10 according to the present embodiment are respectively accommodated in a plurality of accommodating portions 11a formed in the circumferential direction of the holding member 11 and are movable in the radial direction. The biasing members 16 are arranged in a plurality in the circumferential direction between the inner peripheral wall surface 11aa of the accommodating 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. 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.

[0055] In addition, since the weight member 10 according to the present embodiment is formed with an insertion portion 10b through which the urging member 16 can be inserted while opening the surface facing the holding member 11, the urging member 16 can be easily assembled to the weight member 10. Further, in the weight member 10 according to the present embodiment, a groove 10c is formed in the direction from the inner diameter side position to 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, so that the weight member 10 can be stably moved.

[0056] 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.

[0057] In particular, the holding member 11 or the pressure contact member 12 has a groove shape (11b, 12b) along the moving direction of the weight member 10, and the groove shape (11b, 12b) serves as the rolling surface of the first spherical member 14 or the second spherical member 15, so that the weight member 10 can be moved more smoothly. Further, a plurality of the first spherical members 14 and the second spherical members 15 according to the present embodiment are respectively formed across the circumferential direction (width direction of the weight member 10) of the holding member 11, so that the weight member 10 can be moved more stably.

[0058] Here, in the power transmission device K according to the present embodiment, 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, as shown in FIG. 26, there are a first torque region α1 that restricts the operation of the pressure contact assist cam (a cam composed of the gradient surface 4aa and the gradient surface 5a), and a second torque region α2 that allows the operation of the pressure contact assist cam.

[0059] Specifically, as shown in FIGS. 5 and 6, the first clutch member 4a according to the present embodiment has a contact surface 4ad formed on a part of the surface facing the pressure member 5, and as shown in FIGS. 9 and 10, the pressure member 5 has a contact surface 5e formed on a part of the surface 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 a contacting state.

[0060] In this way, in the state where the contact surface 4ad and the contact surface 5e are in contact (the first torque region α1 during the period of t1 to t2 in FIG. 26), in the process where 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 pressure contact assist cam is restricted.

[0061] 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 against the flange portion 4bb of the second clutch member 4b, and the drive-side clutch plate 6 and the driven-side clutch plate 7 are brought into pressure contact. 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 (clutch-off state) in which the weight member 10 is at the outer diameter side position and the pressure member 5 is at the non-operating position.

[0062] Thus, in a state where the contact surface 4ad and the contact surface 5e are separated (the second torque region α2 during the period of t2~ in FIG. 26), in the process in which 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 that the operation of the pressure assist cam is allowed.

[0063] That is, in the present embodiment, in the first torque region α1, the contact surface 4ad of the first clutch member 4a and the contact surface 5e of the pressure member 5 are in contact with each other and the operation of the pressure assist cam is restricted, and in the second torque region α2, the contact surface 4ad of the first clutch member 4a and the contact surface 5e of the pressure member 5 are separated and the operation of the pressure assist cam is allowed.

[0064] Also, in the present embodiment, in the first torque region α1, the centrifugal clutch means 9 moves the second clutch member 4b without moving the first clutch member 4a to maintain the contact state between the first clutch member 4a and the pressure member 5. In the second torque region α2, the centrifugal clutch means 9 moves the second clutch member 4b and the pressure member 5 to separate the contact surface 4ad of the first clutch member 4a and the contact surface 5e of the pressure member 5. In particular, in the present embodiment, it is configured to shift from the first torque region α1 to the second torque region α2 during the operation process of the centrifugal clutch means 9.

[0065] On the other hand, for example, in the case of a conventional power transmission device in which the first clutch member 4a and the pressure member 5 are not in contact and do not have the first torque region α1 (only having the torque region β), as shown in FIG. 27, when 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) is generated, the cam for pressure contact assist operates simultaneously, and the power transmission is suddenly performed unintentionally at the start of the vehicle, making it difficult to drive smoothly.

[0066] According to the present embodiment, in the process of the weight member 10 of the centrifugal clutch means 9 moving 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) increasing, there are a first torque region α1 that restricts the operation of the cam for pressure contact assist and a second torque region α2 that allows the operation of the cam for pressure contact assist. Therefore, in a vehicle equipped with the centrifugal clutch means 9, it is possible to prevent the cam for pressure contact assist from operating inadvertently and the power transmission from being suddenly performed at an unintended timing at the start of the vehicle.

[0067] In addition, the clutch member according to the present embodiment includes a first clutch member 4a connected to the output shaft 3 (output member) and a second clutch member 4b to which the driven-side clutch plate 7 is attached. Since the cam for pressure contact assist is configured such that the gradient surface 4aa formed on the first clutch member 4a and the gradient surface 5a formed on the pressure member 5 face each other, the cam for pressure contact assist can be operated by the first clutch member 4a and the pressure member 5.

[0068] Furthermore, in the first torque region α1, the first clutch member 4a and the pressure member 5 come into contact with each other to restrict the operation of the cam for pressure contact assist, and in the second torque region α2, the first clutch member 4a and the pressure member 5 are separated from each other to allow the operation of the cam for pressure contact assist. Therefore, the restriction of the operation of the cam for pressure contact assist in the first torque region α1 and the allowance of the operation of the cam for pressure contact assist in the second torque region α2 can be accurately and smoothly performed.

[0069] Moreover, in the first torque region α1, the centrifugal clutch means 9 moves the second clutch member 4b without moving the first clutch member 4a to maintain the contact state between the first clutch member 4a and the pressure member 5, and in the second torque region α2, the centrifugal clutch means 9 moves the second clutch member 4a and the pressure member 5 to separate the first clutch member 4a and the pressure member 5. Therefore, the restriction of the operation of the cam for pressure contact assist in the first torque region α1 and the allowance of the operation of the cam for pressure contact assist in the second torque region α2 can be performed by the operation of the centrifugal clutch means 9.

[0070] Particularly, in the present embodiment, since the transition from the first torque region α1 to the second torque region α2 occurs during the operation process of the centrifugal clutch means 9 (the movement process of the weight member 10 from the inner diameter side position to the outer diameter side position), the restriction of the operation of the cam for pressure contact assist in the first torque region α1 and the allowance of the operation of the cam for pressure contact assist in the second torque region α2 can be continuously and smoothly performed.

[0071] The above describes the present embodiment. However, the present invention is not limited thereto. For example, it may not have a cam for a back torque limiter (gradient surfaces 4ab and 5b), may not have an auxiliary clutch plate 17, or the centrifugal clutch means 9 may be of another form (such as one having a weight member made of steel balls). 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, in addition to motorcycles.

Industrial Applicability

[0072] In the process where the weight member of the centrifugal clutch means moves from the inner diameter side position to the outer diameter side position and the transmission torque from the input member to the output member increases, as long as it is a power transmission device having a first torque region for restricting the operation of the pressure contact assist cam and a second torque region for allowing the operation of the pressure contact assist cam, it can also be applied to those having different external shapes or those with other functions added.

Explanation of Signs

[0073] 1 Input gear (input member) 2 Clutch housing 2a Notch 3 Output shaft (output member) 4a First clutch member 4aa Gradient surface (pressure contact assist cam) 4ab Gradient surface (back torque limiter cam) 4ac Boss portion 4ad Contact surface 4b Second clutch member 4ba Spline fitting portion 4bb Flange portion 5 Pressure member 5a Gradient surface (pressure contact assist cam) 5b Gradient surface (back torque limiter cam) 5c Flange portion 5d Insertion hole 5e Contact surface 6 Driving side clutch plate 7 Passive clutch plate 8 Fixed 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 Accommodating part 11aa Inner peripheral wall surface 11b Groove shape 11c Pressing surface 12 Pressing member 12a Taper groove 12b Groove shape 12c Pressing surface 13 Supporting 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 that rotates together with an input member that rotates by the driving force of a vehicle engine and is accommodated 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 alternately formed with the driving side clutch plates attached thereto, and that 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 plate and the driven side clutch plate are brought into pressure contact with each other to enable transmission of the driving force of the engine to the wheels, and a non-operating position where the pressure contact force between the driving side clutch plate and the driven side clutch plate is released to interrupt transmission of the driving force of the engine to the wheels; a centrifugal clutch means including a weight member movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying rotation of the clutch housing, and when the weight member is in the outer diameter side position, the driving side clutch plate and the driven side clutch plate are pressed together to enable transmission of the driving force of the engine to the wheels, and when the weight member is in the inner diameter side position, the pressing force between the driving side clutch plate and the driven side clutch plate is released to interrupt transmission of the driving force of the engine to the wheels; a pressure-contact assist cam for increasing a pressure contact force between the driving clutch plate and the driven clutch plate; A power transmission device comprising: The pressure-contact assist cam is configured such that a sloped surface formed on the clutch member and a sloped surface formed on the pressure member face each other, a first torque range corresponding to an engine speed from an engine speed at which the weight member of the centrifugal clutch means is located at the inner diameter side position to a predetermined engine speed, the first torque range restricting operation of the pressure contact assist cam, and a second torque range corresponding to an engine speed from the predetermined engine speed to an engine speed at which the weight member is located at the outer diameter side position, the second torque range allowing operation of the pressure contact assist cam.

2. 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 formed alternately with the driving side clutch plates and connected to an output member capable of rotating the wheels of the vehicle; a pressure member that is movable between an operating position where the driving side clutch plate and the driven side clutch plate are brought into pressure contact with each other to enable transmission of the driving force of the engine to the wheels, and a non-operating position where the pressure contact force between the driving side clutch plate and the driven side clutch plate is released to interrupt transmission of the driving force of the engine to the wheels; a centrifugal clutch means including a weight member movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying rotation of the clutch housing, and when the weight member is in the outer diameter side position, the driving side clutch plate and the driven side clutch plate are pressed together to enable transmission of the driving force of the engine to the wheels, and when the weight member is in the inner diameter side position, the pressing force between the driving side clutch plate and the driven side clutch plate is released to interrupt transmission of the driving force of the engine to the wheels; a pressure-contact assist cam for increasing a pressure contact force between the driving clutch plate and the driven clutch plate; A power transmission device comprising: The pressure-contact assist cam is configured such that a sloped surface formed on the clutch member and a sloped surface formed on the pressure member face each other, a first torque range corresponding to an engine speed from an engine speed at which the weight member of the centrifugal clutch means is located at the inner diameter side position to a predetermined engine speed, the first torque range restricting operation of the pressure contact assist cam, and a second torque range corresponding to an engine speed from the predetermined engine speed to an engine speed at which the weight member is located at the outer diameter side position, the second torque range allowing operation of the pressure contact assist cam, a power transmission device characterized in that in the first torque region, the clutch member and the pressure member abut to restrict operation of the pressure-assist cam, and in the second torque region, relative movement between the clutch member and the pressure member is permitted to allow operation of the pressure-assist cam.

3. a clutch member that rotates together with an input member that rotates by the driving force of a vehicle engine and is accommodated 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 alternately formed with the driving side clutch plates attached thereto, and that 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 plate and the driven side clutch plate are brought into pressure contact with each other to enable transmission of the driving force of the engine to the wheels, and a non-operating position where the pressure contact force between the driving side clutch plate and the driven side clutch plate is released to interrupt transmission of the driving force of the engine to the wheels; a centrifugal clutch means including a weight member movable from an inner diameter side position to an outer diameter side position by centrifugal force accompanying rotation of the clutch housing, and when the weight member is in the outer diameter side position, the driving side clutch plate and the driven side clutch plate are pressed together to enable transmission of the driving force of the engine to the wheels, and when the weight member is in the inner diameter side position, the pressing force between the driving side clutch plate and the driven side clutch plate is released to interrupt transmission of the driving force of the engine to the wheels; a pressure-contact assist cam for increasing a pressure contact force between the driving clutch plate and the driven clutch plate when the clutch member and the pressure member move relative to each other; A power transmission device comprising: a power transmission device characterized in that when the weight member is in the inner diameter side position, relative movement between the clutch member and the pressure member is restricted, and when the weight member moves from the inner diameter side position to the outer diameter side position and the transmitted torque from the input member to the output member increases, relative movement between the clutch member and the pressure member is permitted.

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