Power transmission device

Abstract

A power transmission device K comprises a centrifugal clutch means 9 having: a weight member 10 configured to be movable to an outer diameter-side position from an inner diameter-side position by centrifugal force associated with rotation of a clutch housing 2; and a pressure contact member 12 that moves in a direction for bringing a driving-side clutch plate 6 and a driven-side clutch plate 7 into pressure contact with each other when the weight member 10 moves to the outer diameter-side position from the inner diameter-side position. The weight member 10 is configured to bring the driving-side clutch plate 6 and the driven-side clutch plate 7 into pressure contact with each other via the pressure contact member 12 in the process where the weight member 10 moves to the outer diameter-side position from the inner diameter-side position. The centrifugal clutch means 9 has, on a portion where the weight member 10 and the pressure contact member 12 contact each other, first gradient surfaces 10a, 12a, and second gradient surfaces 10b, 12b having a greater gradient angle with respect to the axial direction of an output shaft 3 than the first gradient surfaces 10a, 12a.

Description

Technical Field

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

Background Art

[0002] As a conventional power transmission device, for example, as disclosed in Patent Document 1, there has been proposed a centrifugal clutch means including a weight member that moves from an inner diameter side position to an outer diameter side position by centrifugal force accompanying the rotation of a clutch housing, and presses a driving side clutch plate and a driven side clutch plate via a pressing member. According to such a conventional power transmission device, when the clutch housing rotates with the driving of a driving source such as an engine, centrifugal force can be applied to the weight member, and the driving force of the engine can be transmitted to the wheels by pressing the driving side clutch plate and the driven side clutch plate via the pressing member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the above-mentioned conventional power transmission device is applied to a small vehicle, for example, one with a small engine displacement and a low clutch housing rotational speed (i.e., a large primary ratio), it is relatively difficult to set a large centrifugal force on the weight member. For this reason, it was necessary to increase the gradient angle of the cam surface that converts the thrust from the weight member into the contact force between the drive-side clutch plate and the driven-side clutch plate. However, setting a large gradient angle of the cam surface reduces the amount of axial movement of the output member of the contact member. That is, the amount of movement in the contact direction (i.e., the axial direction of the output member) between the drive-side clutch plate and the driven-side clutch plate becomes small. For this reason, there was a risk that it would be difficult to sufficiently transmit the driving force by pressing the drive-side clutch plate and the driven-side clutch plate together.

[0005] The present invention has been made in view of the above, and its object is to provide a power transmission device equipped with a centrifugal clutch means that can secure the axial movement amount of the output member of the contacting member and the thrust by the weight member necessary to sufficiently transmit driving force by pressing the driving clutch plate and the driven clutch plate into contact. [Means for solving the problem]

[0006] The power transmission device according to the present invention includes a clutch member that rotates together with an input member that rotates with the driving force of a drive source, is housed in a clutch housing that holds a plurality of drive-side clutch plates, and is connected to an output member capable of rotating a wheel; a pressure member that is provided so as to be able to approach or move away from the clutch member, and is capable of pressing a plurality of driven-side clutch plates and a plurality of the drive-side clutch plates which are arranged alternately with the drive-side clutch plates; a weight member that is movable from an inner diameter side position to an outer diameter side position by the centrifugal force accompanying the rotation of the clutch housing; and a pressure contact member that is provided so as to be able to contact the weight member and moves in a direction that presses the drive-side clutch plates and the driven-side clutch plates together as the weight member moves from the inner diameter side position to the outer diameter side position, wherein the weight member is at the outer diameter side position The system includes a centrifugal clutch means that, when the drive-side clutch plate and the driven-side clutch plate are pressed together, the driving force of the drive source can be transmitted to the wheel, and when the weight member is in the inner diameter position, the pressure force between the drive-side clutch plate and the driven-side clutch plate can be released to block the transmission of the driving force of the drive source to the wheel, wherein the weight member is configured to press together the drive-side clutch plate and the driven-side clutch plate via the pressure contact member during the process of the weight member moving from the inner diameter position to the outer diameter position, and the centrifugal clutch means has a first gradient surface and a second gradient surface having a greater gradient angle with respect to the axial direction of the output member than the first gradient surface on the portion of the weight member and the pressure contact member that comes into contact with each other.

[0007] According to the power transmission device of the present invention, the centrifugal clutch means has a first gradient surface and a second gradient surface having a greater gradient angle with respect to the axial direction of the output member than the first gradient surface, at the portion of at least one of the weight member and the contact member that comes into contact with the contact member. According to the above embodiment, the required amount of axial movement of the output member by the contact member and the thrust by the weight member can be secured depending on the operating conditions.

[0008] Another power transmission device according to the present invention includes a clutch member that rotates together with an input member that rotates with the driving force of a drive source, is housed in a clutch housing that holds a plurality of drive-side clutch plates, and is connected to an output member capable of rotating a wheel; a pressure member that is provided so as to be able to approach or move away from the clutch member and is capable of pressing a plurality of driven-side clutch plates and a plurality of the drive-side clutch plates which are arranged alternately with the drive-side clutch plates; a weight member that is movable from an inner diameter side position to an outer diameter side position by the centrifugal force accompanying the rotation of the clutch housing; and a pressure contact member that is provided so as to be able to contact the weight member and moves in a direction that presses the drive-side clutch plates and the driven-side clutch plates together as the weight member moves from the inner diameter side position to the outer diameter side position, wherein the weight member is at the outer diameter side position The system includes a centrifugal clutch means that, at a certain time, presses the drive-side clutch plate and the driven-side clutch plate together to enable the transmission of the driving force of the drive source to the wheel, and when the weight member is in the inner diameter position, releases the pressing force between the drive-side clutch plate and the driven-side clutch plate to block the transmission of the driving force of the drive source to the wheel, wherein the weight member is configured to press the drive-side clutch plate and the driven-side clutch plate together via the pressing member during the process of the weight member moving from the inner diameter position to the outer diameter position, and the centrifugal clutch means has a first region and a second region in which the amount of axial movement of the output member of the pressing member is smaller than that of the first region, in the portion of at least one of the weight member and the pressing member where the weight member and the pressing member are in contact.

[0009] According to another power transmission device of the present invention, the centrifugal clutch means has a first region and a second region in which the axial movement of the output member of the pressure contact member is smaller than that of the first region, in the portion where at least one of the weight member and the pressure contact member comes into contact. According to the above embodiment, the required axial movement of the output member of the pressure contact member and the thrust from the weight member can be secured depending on the operating conditions.

[0010] Another power transmission device according to the present invention includes a clutch member that rotates together with an input member that rotates with the driving force of a drive source, is housed in a clutch housing that holds a plurality of drive-side clutch plates, and is connected to an output member capable of rotating a wheel; a pressure member that is provided so as to be able to approach or move away from the clutch member, and is capable of pressing a plurality of driven-side clutch plates and a plurality of the drive-side clutch plates which are alternately arranged with the drive-side clutch plates; a weight member that is movable from an inner diameter side position to an outer diameter side position by the centrifugal force accompanying the rotation of the clutch housing; and a pressure contact member that is provided so as to be able to contact the weight member and moves in a direction that presses the drive-side clutch plates and the driven-side clutch plates together as the weight member moves from the inner diameter side position to the outer diameter side position, wherein the weight member is the outer diameter The system includes a centrifugal clutch means that, when the weight member is in the side position, presses the drive-side clutch plate and the driven-side clutch plate together to enable the transmission of the driving force of the drive source to the wheel, and when the weight member is in the inner diameter side position, releases the pressing force between the drive-side clutch plate and the driven-side clutch plate to block the transmission of the driving force of the drive source to the wheel, wherein the weight member is configured to press the drive-side clutch plate and the driven-side clutch plate together via the pressing member during the process of the weight member moving from the inner diameter side position to the outer diameter side position, and the centrifugal clutch means has a first region and a second region in which the thrust from the weight member is greater than that from the first region, in the portion of at least one of the weight member and the pressing member that contacts the weight member and the pressing member.

[0011] According to another power transmission device of the present invention, the centrifugal clutch means has a first region and a second region where the thrust from the weight member is greater than that from the first region, in the portion where at least one of the weight member and the contact member comes into contact. According to the above embodiment, the required axial movement of the output member of the contact member and the thrust from the weight member can be secured depending on the operating conditions. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a power transmission device equipped with a centrifugal clutch means that can secure the axial movement amount of the output member of the contacting member and the thrust from the weight member necessary to sufficiently transmit driving force by pressing the driving clutch plate and the driven clutch plate into contact. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is an external view showing a power transmission device according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a cross-sectional view along the line III-III in Figure 1. [Figure 4] Figure 4 is an exploded perspective view of the power transmission device according to the first embodiment. [Figure 5] Figure 5 is an exploded perspective view of the power transmission device according to the first embodiment. [Figure 6] Figure 6 is an exploded perspective view of the centrifugal clutch means according to the first embodiment. [Figure 7] Figure 7 is a perspective view showing a weight member according to the first embodiment. [Figure 8] Figure 8 shows a plan view and a rear view of the weight member according to the first embodiment. [Figure 9] Figure 9 is a cross-sectional view along the line IX-IX in Figure 8. [Figure 10] Figure 10 is a perspective view showing a pressure-welding member according to the first embodiment. [Figure 11] Figure 11 shows a plan view and a side view of a pressure-welded member according to the first embodiment. [Figure 12] Figure 12 is a cross-sectional view along the line XII-XII in Figure 11. [Figure 13] Figure 13 is a perspective view showing a retaining member according to the first embodiment. [Figure 14] Figure 14 is a cross-sectional view showing the operation of the centrifugal clutch means according to the first embodiment (with the weight member in the inner diameter position). [Figure 15] Figure 15 is a cross-sectional view showing the operation of the centrifugal clutch means according to the first embodiment (the weight member is at a position between the inner diameter side position and the outer diameter side position). [Figure 16] Figure 16 is a cross-sectional view showing the operation of the centrifugal clutch means according to the first embodiment (the weight member is at the outer diameter side position). [Figure 17] Figure 17 is a schematic view showing a vehicle to which the power transmission device according to the first embodiment is applied. [Figure 18] Figure 18 is a perspective view showing the weight member according to the second embodiment. [Figure 19] Figure 19 is a plan view and a rear view showing the weight member according to the second embodiment. [Figure 20] Figure 20 is a cross-sectional view taken along line XX-XX of FIG. 19. [Figure 21] Figure 21 is a cross-sectional view showing the operation of the centrifugal clutch means according to the second embodiment (the weight member is at the inner diameter side position). [Figure 22] Figure 22 is a cross-sectional view showing the operation of the centrifugal clutch means according to the second embodiment (the weight member is at a position between the inner diameter side position and the outer diameter side position). [Figure 23] Figure 23 is a cross-sectional view showing the operation of the centrifugal clutch means according to the second embodiment (the weight member is at the outer diameter side position). [Figure 24] Figure 24 is a perspective view showing the weight member according to the third embodiment. [Figure 25] Figure 25 is a plan view and a rear view showing the weight member according to the third embodiment. ​​​​​​​​​​Figure 29 is a cross-sectional view showing the operation of the centrifugal clutch means according to the third embodiment (with the weight member in the outer diameter position). [Figure 30] Figure 30 is a cross-sectional view showing the operation of the centrifugal clutch means according to the fourth embodiment (with the weight member in the inner diameter position). [Figure 31] Figure 31 is a cross-sectional view showing the operation of the centrifugal clutch means according to the fourth embodiment (the position of the weight member between the inner diameter side position and the outer diameter side position). [Figure 32] Figure 32 is a cross-sectional view showing the operation of the centrifugal clutch means according to the fourth embodiment (with the weight member in the outer diameter position). [Figure 33] Figure 33 is a cross-sectional view showing the operation of the centrifugal clutch means according to the fifth embodiment (with the weight member in the inner diameter position). [Figure 34] Figure 34 is a cross-sectional view showing the operation of the centrifugal clutch means according to the fifth embodiment (the position of the weight member between the inner diameter side position and the outer diameter side position). [Figure 35] Figure 35 is a cross-sectional view showing the operation of the centrifugal clutch means according to the fifth embodiment (with the weight member in the outer diameter position). [Figure 36] Figure 36 is a cross-sectional view showing the operation of the centrifugal clutch means according to the sixth embodiment (with the weight member in the inner diameter position). [Figure 37] Figure 37 is a cross-sectional view showing the operation of the centrifugal clutch means according to the sixth embodiment (the position of the weight member between the inner diameter side position and the outer diameter side position). [Figure 38] Figure 38 is a cross-sectional view showing the operation of the centrifugal clutch means according to the sixth embodiment (with the weight member in the outer diameter position). [Figure 39] Figure 39 is a graph showing the relationship between engine speed and the amount of displacement of the pressure-welded member. [Figure 40] Figure 40 is a graph showing the relationship between engine speed and thrust generated by the weight member. [Modes for carrying out the invention]

[0014] <First Embodiment> Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in Figure 17, the power transmission device K is installed in a vehicle and is used to arbitrarily transmit or interrupt the driving force of the engine E to the drive wheel T via the transmission M. The engine E is an example of a power source. The drive wheel T is an example of a wheel. As shown in Figures 1 to 16, the power transmission device K includes a clutch housing 2 in which an input gear 1 that rotates with the driving force of the vehicle's engine E is formed, an output shaft 3 connected to the transmission M, a clutch member 4, a pressure member 5, a plurality of drive-side clutch plates 6 and a plurality of driven-side clutch plates 7, and a centrifugal clutch means 9 having a weight member 10. In the figures, reference numeral 8 indicates a fixing member, reference numeral S indicates a clutch spring, reference numeral f indicates a return spring, and reference numeral B indicates a bolt. The input gear 1 is an example of an input member. The output shaft 3 is an example of an output member.

[0015] The input gear 1 is configured to rotate around the output shaft 3 when a driving force (rotational force) transmitted from the engine E is input. The input gear 1 is connected to the clutch housing 2 by rivets or the like. As shown in Figures 4 and 5, the clutch housing 2 is formed in a cylindrical shape with one end open. The clutch housing 2 rotates together with the input gear 1 due to the driving force of the engine E.

[0016] As shown in Figures 4 and 5, the clutch housing 2 has a plurality of notches 2a formed in the circumferential direction. The plurality of drive-side clutch plates 6 are fitted into the notches 2a and mounted. That is, the clutch housing 2 holds the plurality of drive-side clutch plates 6. The drive-side clutch plates 6 are made of a plate material having a substantially annular shape. The drive-side clutch plates 6 are configured to be movable along the axial direction of the clutch housing 2 (i.e., the axial direction of the output shaft 3) and to be rotatable integrally with the clutch housing 2.

[0017] As shown in Figure 2, the clutch member 4 is housed in the clutch housing 2. The clutch member 4 holds a plurality of driven clutch plates 7, which are arranged alternately with the drive clutch plate 6. The clutch member 4 is connected to an output shaft 3 that can rotate the drive wheels T via the vehicle's transmission M. As shown in Figures 4 and 5, the clutch member 4 includes a first clutch member 4a and a second clutch member 4b. The first clutch member 4a fits into the second clutch member 4b.

[0018] As shown in Figures 4 and 5, the first clutch member 4a has an insertion hole 4ac formed in the center. The output shaft 3 is inserted through the insertion hole 4ac, and the splines formed on each other interlock and connect them in the rotational direction. That is, the first clutch member 4a is connected to the output shaft 3. The second clutch member 4b has an annular outer peripheral wall 4bc and a flange portion 4bb extending radially outward from the outer peripheral wall 4bc. A spline fitting portion 4ba is formed on the outer peripheral wall 4bc. The spline fitting portion 4ba has an uneven shape integrally formed over substantially the entire circumference of the outer peripheral wall 4bc. The driven clutch plate 7 is attached to the groove of the spline fitting portion 4ba by spline fitting. That is, the second clutch member 4b holds the driven clutch plate 7. The driven clutch plate 7 is configured to be movable along the axial direction of the clutch member 4 (e.g., the second clutch member 4b) (i.e., the axial direction of the output shaft 3) and to be rotatable integrally with the clutch member 4 (e.g., the first clutch member 4a and the second clutch member 4b). The second clutch member 4b is configured to be movable in the axial direction of the output shaft 3.

[0019] As shown in Figure 4, the pressure member 5 is composed of a disc-shaped member with a flange portion 5a formed on its peripheral edge. The pressure member 5 is assembled to the clutch member 4. The pressure member 5 is provided so as to be able to move closer to or further away from the clutch member 4. The pressure member 5 is configured to be able to press the drive-side clutch plate 6 and the driven-side clutch plate 7 together with the clutch member 4. By pressing the drive-side clutch plate 6 and the driven-side clutch plate 7 together, the pressure member 5 can transmit the driving force of the engine E to the drive wheels W. In other words, the drive-side clutch plate 6 and the driven-side clutch plate 7 are arranged in a stacked state between the flange portion 5a of the pressure member 5 and the flange portion 4bb of the second clutch member 4b. When the second clutch member 4b moves toward the pressure member 5 (in the direction of arrow DR2 in Figure 2), the drive-side clutch plate 6 and the driven-side clutch plate 7 are pressed against each other, and the rotational force of the clutch housing 2 is transmitted to the output shaft 3 via the second clutch member 4b and the first clutch member 4a. On the other hand, when the second clutch member 4b moves toward the direction away from the pressure member 5 (in the direction of arrow DR1 in Figure 2), the pressing force between the drive-side clutch plate 6 and the driven-side clutch plate 7 is released, the first clutch member 4a and the second clutch member 4b no longer follow the rotation of the clutch housing 2, and the rotational force of the clutch housing 2 is no longer transmitted to the output shaft 3. The drive-side clutch plate 6 and the driven-side clutch plate 7 are provided so as to be movable in the axial direction of the output shaft 3 relative to the second clutch member 4b.

[0020] Thus, when the drive clutch plate 6 and the driven clutch plate 7 are pressed together, the rotational force input to the clutch housing 2 (i.e., the driving force of the engine E) is transmitted to the drive wheel T side (i.e., the transmission M) via the output shaft 3. Conversely, when the pressure between the drive clutch plate 6 and the driven clutch plate 7 is released, the rotational force input to the clutch housing 2 is not transmitted to the output shaft 3.

[0021] As shown in Figure 2, the centrifugal clutch means 9 has a weight member 10 that is movable from an inner diameter side position (see Figure 14) to an outer diameter side position (see Figure 16) by the centrifugal force accompanying the rotation of the clutch housing 2. The centrifugal clutch means 9 is located on the opening side (right side in Figure 2) of the clutch housing 2. The centrifugal clutch means 9 is located on the opposite side of the pressure member 5, with the drive-side clutch plate 6 and the driven-side clutch plate 7 in between. Here, the centrifugal clutch means 9 is located on the side of the pressure member 5 in the direction of arrow DR1 in Figure 2. When the weight member 10 is in the outer diameter side position, the centrifugal clutch means 9 presses the drive-side clutch plate 6 and the driven-side clutch plate 7 into contact, enabling the transmission of the engine E's driving force to the drive wheel T. The centrifugal clutch means 9 is configured to apply a pressing force to the drive-side clutch plate 6 and the driven-side clutch plate 7 during the process in which the weight member 10 moves from the inner diameter side position to the outer diameter side position. The centrifugal clutch mechanism 9 is configured such that when the weight member 10 is in the inner diameter position, it can release the contact force between the drive-side clutch plate 6 and the driven-side clutch plate 7, thereby blocking the transmission of the engine E's driving force to the drive wheels T.

[0022] As shown in Figure 6, the centrifugal clutch means 9 includes a plurality of weight members 10, a holding member 11 that holds the weight members 10 so as to be movable between an inner diameter side position and an outer diameter side position, a pressure contact member 12, and a plurality of biasing springs 13.

[0023] As shown in Figures 7 to 9, the weight member 10 has a main body portion 10h, a weight member side cam surface K1 formed on the main body portion 10h, a groove portion 10c formed on the main body portion 10h that holds the biasing spring 13 (see Figure 6), and a sliding surface 10d formed on the main body portion 10h that is slidable against the sliding surface 11b of the holding member 11 (see Figure 13). The weight member 10 is housed in the holding member 11. When no centrifugal force is applied, the weight member 10 is held in the inner diameter side position (see Figure 14). When centrifugal force is applied, the weight member 10 moves radially outward against the biasing force of the biasing spring 13 and reaches the outer diameter side position (see Figure 16). In the process of moving from the inner diameter side position to the outer diameter side position, the weight member 10 moves the clutch member 4 (here, the second clutch member 4b) in the direction toward the pressure member 5 (direction of arrow DR2 in Figure 2). The weight member 10 is configured to press against the drive-side clutch plate 6 and the driven-side clutch plate 7 via the pressure contact member 12 during the process of the weight member 10 moving from the inner diameter side position to the outer diameter side position. However, it is not necessary for the weight member 10 to press against the drive-side clutch plate 6 and the driven-side clutch plate 7 via the pressure contact member 12 at the same time that it starts moving from the inner diameter side position to the outer diameter side position. The weight member 10 may press against the drive-side clutch plate 6 and the driven-side clutch plate 7 via the pressure contact member 12 after it has moved a predetermined distance from the inner diameter side position to the outer diameter side position.

[0024] As shown in Figure 14, the weight member side cam surface K1 is provided so as to be able to contact the pressure contact member side cam surface K2, which will be described later. The weight member side cam surface K1 is the part that contacts the pressure contact member 12. As shown in Figure 9, the weight member 10 has a first gradient surface 10a and a second gradient surface 10b on the weight member side cam surface K1, the gradient angle of the first gradient surface 10a with respect to the axial direction of the output shaft 3 is larger than that of the first gradient surface 10a. The first gradient surface 10a is located radially outward from the second gradient surface 10b. The first gradient surface 10a is a flat surface. The second gradient surface 10b is a flat surface. The gradient angle α of the first gradient surface 10a with respect to the axial direction of the output shaft 3 is smaller than the gradient angle β of the second gradient surface 10b with respect to the axial direction of the output shaft 3. In this embodiment, the first gradient surface 10a and the second gradient surface 10b are continuous, but they may be connected via a curved surface. Thus, the centrifugal clutch means 9 has a first gradient surface 10a and a second gradient surface 10b on the portion of the weight member 10 where the weight member 10 and the pressure contact member 12 come into contact (here, the weight member side cam surface K1). When the engine speed increases to a predetermined number of revolutions per minute and the weight member 10 moves a predetermined distance in the radial direction, the amount of axial movement of the output shaft 3 of the pressure contact member 12 on the second gradient surface 10b is smaller than the amount of axial movement of the output shaft 3 of the pressure contact member 12 on the first gradient surface 10a. The thrust of the weight member 10 generated on the second gradient surface 10b is greater than the thrust of the weight member 10 generated on the first gradient surface 10a. The first gradient surface 10a is an example of a first region. The second gradient surface 10b is an example of a second region.

[0025] As shown in Figure 2, the holding member 11 holds the weight member 10 so that it can move between an inner diameter position and an outer diameter position. As shown in Figure 13, the holding member 11 has an annular body portion 11c, a wall portion 11a extending from the outer peripheral edge of the body portion 11c, and a sliding surface 11b on which the weight member 10 slides. The wall portion 11a is in contact with one end of the biasing spring 13.

[0026] The contact member 12 is provided so as to be able to contact the weight member 10. The contact member 12 is configured to move in a direction (direction of arrow DR2 in Figure 14) that causes the drive-side clutch plate 6 and the driven-side clutch plate 7 to press against each other as the weight member 10 moves from an inner diameter side position (see Figure 14) to an outer diameter side position (see Figure 16). The contact member 12 is configured to be able to press against the drive-side clutch plate 6 and the driven-side clutch plate 7. As shown in Figures 10 to 12, the contact member 12 has an annular main body portion 12d, a plurality of contact member-side cam surfaces K2 formed over the circumferential direction of the main body portion 12d, a pressing surface 12c formed on the side of the main body portion 12d opposite to the side on which the contact member-side cam surfaces K2 are formed, and a plurality of protrusions 12e formed over the circumferential direction of the main body portion 12d. The contact member 12 is attached to the clutch housing 2 by the fitting of its projection 12e into the notch 2a (see Figure 4) of the clutch housing 2. The contact member 12 is provided to be movable in the axial direction of the clutch housing 2 (i.e., in the axial direction of the output shaft 3). The contact member 12 is provided to engage with the clutch housing 2 in the rotational direction and to be rotatable together with the clutch housing 2.

[0027] As shown in Figure 14, the cam surface K2 on the contact member side is provided so as to be able to contact the cam surface K1 on the weight member side. The cam surface K2 on the contact member side is the portion that contacts the weight member 10. As shown in Figure 12, the contact member 12 has a first gradient surface 12a and a second gradient surface 12b on the cam surface K2 on the contact member side, the gradient angle with respect to the axial direction of the output shaft 3 is larger than that of the first gradient surface 12a. The first gradient surface 12a is located radially inward from the second gradient surface 12b. The first gradient surface 12a is a flat surface. The second gradient surface 12b is a flat surface. The gradient angle α of the first gradient surface 12a with respect to the axial direction of the output shaft 3 is smaller than the gradient angle β of the second gradient surface 12b with respect to the axial direction of the output shaft 3. The first gradient surface 12a is provided so as to be able to contact the first gradient surface 10a of the cam surface K1 on the weight member side. The second gradient surface 12b is provided so as to be able to contact the second gradient surface 10b of the weight member side cam surface K1. In this embodiment, the first gradient surface 12a and the second gradient surface 12b are continuous, but they may be connected via a curved surface. Thus, the centrifugal clutch means 9 has a first gradient surface 12a and a second gradient surface 12b at the portion of the pressure contact member 12 where the weight member 10 and the pressure contact member 12 come into contact (here, the pressure contact member side cam surface K2). When the engine speed increases to a predetermined number of revolutions per minute and the weight member 10 moves a predetermined distance in the radial direction, the amount of axial movement of the output shaft 3 of the pressure contact member 12 at the second gradient surface 12b is smaller than the amount of axial movement of the output shaft 3 of the pressure contact member 12 at the first gradient surface 12a. The thrust of the weight member 10 generated at the second gradient surface 12b is greater than the thrust of the weight member 10 generated at the first gradient surface 12a. The first gradient surface 12a is an example of a first region. The second gradient surface 12b is an example of the second region.

[0028] The thrust generated by the weight member 10 during its movement from the inner diameter side position (see Figure 14) to the outer diameter side position (see Figure 16) is transmitted to the contact member 12 via the weight member side cam surface K1 and the contact member side cam surface K2. As a result, the contact member 12 moves in a direction that brings the drive side clutch plate 6 and the driven side clutch plate 7 into contact (in the direction of arrow DR2 in Figure 14). As shown in Figures 14 to 16, the weight member side cam surface K1 and the contact member side cam surface K2 are configured such that, during the movement of the weight member 10 from the inner diameter side position (see Figure 14) to the outer diameter side position (see Figure 16), the gradient surfaces acting as cam surfaces transition from the first gradient surface 10a and the first gradient surface 12a to the second gradient surface 10b and the second gradient surface 12b. During the process in which the weight member 10 moves from the inner diameter side position to the outer diameter side position, the first inclined surface 10a and the first inclined surface 12a act as cam surfaces until the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins, and after the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins, the second inclined surface 10b and the second inclined surface 12b act as cam surfaces.

[0029] As shown in Figure 14, during the process of the weight member 10 moving from the inner diameter side position to the outer diameter side position, the first inclined surface 10a and the first inclined surface 12a on the weight member side cam surface K1 and the contact member side cam surface K2 slide in contact with each other until the driving clutch plate 6 and the driven clutch plate 7 begin to press against each other. As a result, the thrust generated when the weight member 10 moves from the inner diameter side position to the outer diameter side position is transmitted to the contact member 12 via the first inclined surface 10a and the first inclined surface 12a. The contact member 12 then moves in the direction that presses the driving clutch plate 6 and the driven clutch plate 7 against each other (in the direction of arrow DR2 in Figure 14). At this time, the thrust of the weight member 10 transmitted to the contact member 12 is relatively small, but the amount of axial movement of the output shaft 3 of the contact member 12 is relatively large.

[0030] Then, as shown in Figure 15, when the weight member 10 moves further from the inner diameter side position to the outer diameter side position and the drive side clutch plate 6 and the driven side clutch plate 7 begin to press against each other, the boundary between the first slope surface 10a and the second slope surface 10b of the weight member side cam surface K1 and the boundary between the first slope surface 12a and the second slope surface 12b of the press-fitting member side cam surface K2 come into contact with each other.

[0031] Then, as shown in Figure 16, when the weight member 10 moves further from the inner diameter side position to the outer diameter side position, after the driving clutch plate 6 and the driven clutch plate 7 begin to press against each other at the weight member side cam surface K1 and the pressure contact member side cam surface K2, the second gradient surface 10b and the second gradient surface 12b come into contact with each other and slide. As a result, the thrust generated when the weight member 10 moves from the inner diameter side position to the outer diameter side position is transmitted to the pressure contact member 12 via the second gradient surface 10b and the second gradient surface 12b. The pressure contact member 12 then moves further in the direction that presses the driving clutch plate 6 and the driven clutch plate 7 together (in the direction of arrow DR2 in Figure 16). At this time, the amount of axial movement of the output shaft 3 of the pressure contact member 12 becomes relatively small, but the thrust of the weight member 10 transmitted to the pressure contact member 12 becomes relatively large.

[0032] Furthermore, the weight member 10 and the pressure contact member 12 may be configured such that, as the rotational speed of the engine E increases, they come into contact with each other at the first inclined surface 10a and the first inclined surface 12a (i.e., in the first region), and then come into contact with each other at the second inclined surface 10b and the second inclined surface 12b (i.e., in the second region). Also, when the rotational speed of the engine E is lower than the rotational speed at which the drive-side clutch plate 6 and the driven-side clutch plate 7 begin to come into contact, the weight member 10 and the pressure contact member 12 may be configured such that they come into contact with each other at the first inclined surface 10a and the first inclined surface 12a (i.e., in the first region), and then come into contact with each other at the second inclined surface 10b and the second inclined surface 12b (i.e., in the second region). When the rotational speed of the engine E is lower than the rotational speed at which the pressure contact between the drive clutch plate 6 and the driven clutch plate 7 is completed, the weight member 10 and the pressure contact member 12 may be configured to come into contact with each other at the first inclined surface 10a and the first inclined surface 12a (i.e., in the first region), and then come into contact with each other at the second inclined surface 10b and the second inclined surface 12b (i.e., in the second region). In the region where the rotational speed of the engine E is higher than the rotational speed at which the pressure contact between the drive clutch plate 6 and the driven clutch plate 7 is completed, the pressure contact between the drive clutch plate 6 and the driven clutch plate 7 is maintained.

[0033] Figure 39 is a graph showing the relationship between the rotational speed of engine E and the axial displacement of the output shaft 3 of the pressure contact member 12. In Figure 39, the horizontal axis represents the rotational speed of engine E, and the vertical axis represents the axial displacement of the output shaft 3 of the pressure contact member 12. Figure 40 is a graph showing the relationship between the rotational speed of engine E and the thrust provided by the weight member 10. In Figure 40, the horizontal axis represents the rotational speed of engine E, and the vertical axis represents the thrust provided by the weight member 10. In Figures 39 and 40, rotational speed EID indicates the rotational speed of engine E at idle, rotational speed EC indicates the rotational speed of engine E when the press-fitting of the drive-side clutch plate 6 and the driven-side clutch plate 7 begins (here, when the inclined surfaces acting as cam surfaces transition from the first inclined surface 10a and the first inclined surface 12a to the second inclined surface 10b and the second inclined surface 12b), rotational speed EIN indicates the rotational speed of engine E when the driving force of engine E begins to be transmitted to the drive wheel T, rotational speed EST indicates the rotational speed of engine E when the press-fitting of the drive-side clutch plate 6 and the driven-side clutch plate 7 is fully pressed together (when the press-fitting of the drive-side clutch plate 6 and the driven-side clutch plate 7 is completed), and rotational speed EE indicates the rotational speed of engine E when the weight member 10 reaches the outer diameter side position. As shown in Figures 39 and 40, when the rotational speed of engine E is between rotational speed EID and rotational speed EC, the axial displacement LM1 of the output shaft 3 of the pressure contact member 12 is relatively large, and the thrust FM1 due to the weight member 10 is relatively small. On the other hand, when the rotational speed of engine E is between rotational speed EC and rotational speed EE, the axial displacement LM2 of the output shaft 3 of the pressure contact member 12 is relatively small (displacement LM2 < displacement LM1), and the thrust FM2 due to the weight member 10 is relatively large (thrust FM2 > thrust FM1).

[0034] As described above, according to the power transmission device K of this embodiment, the centrifugal clutch means 9 has first gradient surfaces 10a and 12a and second gradient surfaces 10b and 12b on the weight member side cam surface K1, each having a larger gradient angle with respect to the axial direction of the output shaft 3 than the first gradient surfaces 10a and 12a. According to the above embodiment, the required amount of axial movement of the output shaft 3 by the pressure contact member 12 and the thrust by the weight member 10 can be secured depending on the operating state.

[0035] In the power transmission device K of this embodiment, as the rotational speed of the engine E increases, the weight member 10 and the pressure contact member 12 may come into contact with each other at the first inclined surfaces 10a and 12a, and then at the second inclined surfaces 10b and 12b. According to the above embodiment, the amount of axial movement of the pressure contact member 12 can be increased first, and then the thrust by the weight member 10 can be increased.

[0036] In the power transmission device K of this embodiment, the first gradient surface 10a and the second gradient surface 10b may be connected via a curved surface, and the first gradient surface 12a and the second gradient surface 12b may also be connected via a curved surface. According to the above embodiment, since the first gradient surface 10a and the second gradient surface 10b are connected via a curved surface, and the first gradient surface 12a and the second gradient surface 12b are connected via a curved surface, the contact portion between the weight member 10 and the pressure contact member 12 can be smoothly transitioned from the first gradient surfaces 10a and 12a to the second gradient surfaces 10b and 12b.

[0037] In the power transmission device K of this embodiment, when the rotational speed of the engine E is lower than the rotational speed at which the drive-side clutch plate 6 and the driven-side clutch plate 7 begin to press against each other, the weight member 10 and the contact member 12 may contact each other at the first inclined surfaces 10a and 12a, and then at the second inclined surfaces 10b and 12b. According to the above embodiment, when the rotational speed is lower than the rotational speed at which the drive-side clutch plate 6 and the driven-side clutch plate 7 begin to press against each other, the contact portion between the weight member 10 and the contact member 12 is moved from the first inclined surfaces 10a and 12a to the second inclined surfaces 10b and 12b. As a result, the necessary axial movement of the output shaft 3 of the contact member 12 can be secured before the drive-side clutch plate 6 and the driven-side clutch plate 7 begin to press against each other, and after the drive-side clutch plate 6 and the driven-side clutch plate 7 begin to press against each other, the necessary thrust can be secured by the weight member 10.

[0038] In the power transmission device K of this embodiment, when the rotational speed of the engine E is lower than the rotational speed at which the press-fitting between the drive-side clutch plate 6 and the driven-side clutch plate 7 is completed, the weight member 10 and the press-fitting member 12 may come into contact with each other at the first inclined surfaces 10a and 12a, and then at the second inclined surfaces 10b and 12b. According to the above embodiment, when the rotational speed is lower than the rotational speed at which the press-fitting between the drive-side clutch plate 6 and the driven-side clutch plate 7 is completed, the contact portion between the weight member 10 and the press-fitting member 12 is moved from the first inclined surfaces 10a and 12a to the second inclined surfaces 10b and 12b. As a result, the necessary axial movement of the output shaft 3 of the press-fitting member 12 can be secured until the press-fitting between the drive-side clutch plate 6 and the driven-side clutch plate 7 is completed, and after the press-fitting between the drive-side clutch plate 6 and the driven-side clutch plate 7 is completed, the necessary thrust can be secured by the weight member 10.

[0039] In the power transmission device K of this embodiment, the weight member 10 has a sliding surface 10d that can slide against the holding member 11, and the weight member 10 has a first gradient surface 10a and a second gradient surface 10b at the portion where the weight member 10 and the pressure contact member 12 come into contact (for example, the cam surface K1 on the weight member side), and the pressure contact member 12 may have a first gradient surface 12a and a second gradient surface 12b at the portion where the weight member 10 and the pressure contact member 12 come into contact (for example, the cam surface K2 on the pressure contact member side). According to the above embodiment, a weight member 10 having a sliding surface 10d that can slide against the holding member 11 can be effectively applied.

[0040] Furthermore, according to the power transmission device K of this embodiment, the centrifugal clutch means 9 has first gradient surfaces 10a and 12a as a first region, and second gradient surfaces 10b and 12b as a second region in which the amount of axial movement of the output shaft 3 of the contact member 12 is smaller than that of the first region. According to the above embodiment, the required amount of axial movement of the output shaft 3 of the contact member 12 and the thrust by the weight member 10 can be secured depending on the operating state. Note that the thrust by the weight member 10 is greater in the second region than in the first region.

[0041] In the power transmission device K of this embodiment, as the rotational speed of the engine E increases, the weight member 10 and the pressure contact member 12 may come into contact with each other at the first gradient surfaces 10a and 12a, which constitute the first region, and then come into contact with each other at the second gradient surfaces 10b and 12b, which constitute the second region. According to the above embodiment, the amount of axial movement of the pressure contact member 12 can be increased first, and then the thrust by the weight member 10 can be increased.

[0042] In the power transmission device K of this embodiment, the first region is a first gradient surface 10a, 12a consisting of a flat surface, and the second region is a second gradient surface 10b, 12b consisting of a flat surface, and the weight member 10 and the pressure contact member 12 may be configured to be in contact with each other at the first gradient surface 10a, 12a and the second gradient surface 10b, 12b. According to the above embodiment, the amount of movement of the pressure contact member 12 and the thrust by the weight member 10 can be smoothly changed in the first region and the second region.

[0043] <Second Embodiment> As shown in Figures 21-23, the power transmission device 200K according to the second embodiment has a centrifugal clutch means 209 having a weight member 14. Components similar to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0044] As shown in Figure 21, the centrifugal clutch means 209 includes a plurality of weight members 14, a holding member 11 that holds the weight members 14 so as to be movable between an inner diameter side position and an outer diameter side position, a pressure contact member 15, and a plurality of biasing springs 13.

[0045] As shown in Figures 18 to 20, the weight member 14 is configured to move from an inner diameter position (see Figure 21) to an outer diameter position (see Figure 23) due to the centrifugal force accompanying the rotation of the clutch housing 2. The weight member 14 has a main body portion 14h, a spherical member 14a that can move while making point contact or rolling relative to the holding member 11, a holding hole 14f formed in the main body portion 14h and holding the spherical member 14a, and a groove portion 14b formed in the main body portion 14h and holding the biasing spring 13. The spherical member 14a is an example of a contact portion.

[0046] The contact member 15 is provided so as to be able to contact the weight member 14. The contact member 15 is configured to move in a direction (direction of arrow DR2 in Figure 21) that causes the drive-side clutch plate 6 and the driven-side clutch plate 7 to press against each other as the weight member 14 moves from an inner diameter side position (see Figure 21) to an outer diameter side position (see Figure 23). The contact member 15 is configured to be able to press against the drive-side clutch plate 6 and the driven-side clutch plate 7. As shown in Figure 21, the contact member 15 has a contact member side cam surface 200K2 formed over the circumferential direction of the main body portion 12d.

[0047] As shown in Figure 21, the cam surface 200K2 on the contact member side is provided so as to be able to contact the spherical member 14a. The cam surface 200K2 on the contact member side is the portion that contacts the weight member 14. The contact member 15 has a first gradient surface 15a and a second gradient surface 15b on the cam surface 200K2 on the contact member side, the gradient angle of the first gradient surface 15a with respect to the axial direction of the output shaft 3 is larger than that of the first gradient surface 15a. The first gradient surface 15a is located radially inward from the second gradient surface 15b. The first gradient surface 15a is a flat surface. The second gradient surface 15b is a curved surface. The first gradient surface 15a and the second gradient surface 15b are provided so as to be able to contact the spherical member 14a. In this embodiment, the first gradient surface 15a and the second gradient surface 15b are continuous, but they may be connected via a curved surface. When the engine speed increases to a predetermined speed and the weight member 10 moves a predetermined distance in the radial direction, the amount of axial movement of the output shaft 3 of the pressure contact member 15 on the second gradient surface 15b is smaller than the amount of axial movement of the output shaft 3 of the pressure contact member 15 on the first gradient surface 15a. Also, when the engine speed increases to a predetermined speed and the weight member 10 moves a predetermined distance in the radial direction, the thrust of the weight member 14 generated on the second gradient surface 15b is greater than the thrust of the weight member 14 generated on the first gradient surface 15a. The first gradient surface 15a is an example of a first region. The second gradient surface 12b is an example of a second region.

[0048] The thrust generated by the weight member 14 during its movement from the inner diameter side position (see Figure 21) to the outer diameter side position (see Figure 23) is transmitted to the contact member 15 via the spherical member 14a and the contact member side cam surface 200K2. As a result, the contact member 15 moves in a direction that brings the drive-side clutch plate 6 and the driven-side clutch plate 7 into contact (in the direction of arrow DR2 in Figure 21). As shown in Figures 21 to 23, the spherical member 14a and the contact member side cam surface 200K2 are configured such that, during the movement of the weight member 14 from the inner diameter side position (see Figure 21) to the outer diameter side position (see Figure 23), the gradient surface acting as a cam surface on the spherical member 14a transitions from the first gradient surface 15a to the second gradient surface 15b. During the process in which the weight member 14 moves from the inner diameter side position to the outer diameter side position, the first inclined surface 15a acts as a cam surface until the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins, and after the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins, the second inclined surface 15b acts as a cam surface.

[0049] As shown in Figure 21, during the process of the weight member 14 moving from the inner diameter side position to the outer diameter side position, the spherical member 14a and the first inclined surface 15a slide in contact with each other at the cam surface K2 on the contact member side until the driving clutch plate 6 and the driven clutch plate 7 begin to press against each other. As a result, the thrust generated when the weight member 14 moves from the inner diameter side position to the outer diameter side position is transmitted to the contact member 15 via the spherical member 14a and the first inclined surface 15a. The contact member 15 then moves in the direction that presses the driving clutch plate 6 and the driven clutch plate 7 together (in the direction of arrow DR2 in Figure 21). At this time, the thrust of the weight member 14 transmitted to the contact member 15 is relatively small, but the amount of axial movement of the output shaft 3 of the contact member 15 is relatively large.

[0050] Then, as shown in Figure 22, when the weight member 14 moves further from the inner diameter side position to the outer diameter side position and the drive-side clutch plate 6 and the driven-side clutch plate 7 begin to press against each other, the spherical member 14a and the boundary between the first gradient surface 15a and the second gradient surface 15b of the cam surface 200K2 on the press-fitting member side come into contact with each other.

[0051] Then, as shown in Figure 23, when the weight member 14 moves further from the inner diameter side position to the outer diameter side position, after the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins at the spherical member 14a and the pressure contact member side cam surface 200K2, the spherical member 14a and the second inclined surface 15b come into contact with each other and slide. As a result, the thrust generated when the weight member 14 moves from the inner diameter side position to the outer diameter side position is transmitted to the pressure contact member 15 via the spherical member 14a and the second inclined surface 15b. The pressure contact member 15 then moves further in the direction that presses the drive-side clutch plate 6 and the driven-side clutch plate 7 together (in the direction of arrow DR2 in Figure 23). At this time, the amount of axial movement of the output shaft 3 of the pressure contact member 15 becomes relatively small, but the thrust of the weight member 14 transmitted to the pressure contact member 15 becomes relatively large.

[0052] In the power transmission device 200K of this embodiment, the weight member 14 has a spherical member 14a that is movable while making point contact with the holding member 11, and the pressure contact member 15 has a first gradient surface 15a and a second gradient surface 15b on the cam surface 200K2 on the pressure contact member side. According to the above embodiment, the weight member 14 having a spherical member 14a that is movable while making point contact with the holding member 11 can be effectively applied.

[0053] <Third Embodiment> As shown in Figures 27-29, the power transmission device 300K according to the third embodiment has a centrifugal clutch means 309 having a weight member 16. Components similar to those in the first and second embodiments are denoted by the same reference numerals, and detailed descriptions are omitted.

[0054] As shown in Figures 24 to 26, the weight member 16 is configured to move from an inner diameter position (see Figure 27) to an outer diameter position (see Figure 29) due to the centrifugal force accompanying the rotation of the clutch housing 2. The weight member 16 has a main body portion 16h, a pair of rolling members 16a and 16b that can move while making point contact or rolling relative to the holding member 11, a holding hole 16f formed in the main body portion 16h to hold the rolling members 16a and 16b, and a groove portion 16c formed in the main body portion 16h to hold the biasing spring 13. The rolling member 16a is provided so as to be able to contact the cam surface 200K2 on the pressure contact member side. The rolling member 16b is provided so as to be able to contact the holding member 11. The rolling members 16a and 16b are held in the holding hole 16f so as to be in contact with each other. The rolling members 16a and 16b are examples of contact portions.

[0055] The thrust of the weight member 16 generated during the process of the weight member 16 moving from the inner diameter side position (see Figure 27) to the outer diameter side position (see Figure 29) is transmitted to the contact member 15 via the rolling members 16a, 16b and the cam surface 200K2 on the contact member side. As a result, the contact member 15 moves in a direction that brings the drive-side clutch plate 6 and the driven-side clutch plate 7 into contact (in the direction of arrow DR2 in Figure 27). As shown in Figures 27 to 29, the rolling member 16a and the cam surface 200K2 on the contact member side are configured such that, during the process of the weight member 16 moving from the inner diameter side position (see Figure 27) to the outer diameter side position (see Figure 29), the gradient surface acting as a cam surface on the rolling member 16a transitions from the first gradient surface 15a to the second gradient surface 15b. During the process in which the weight member 16 moves from the inner diameter side position to the outer diameter side position, the first gradient surface 15a acts as a cam surface until the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins, and after the pressure contact between the drive-side clutch plate 6 and the driven-side clutch plate 7 begins, the second gradient surface 15b acts as a cam surface. The operation and effects of the third embodiment are the same as those of the second embodiment.

[0056] Preferred embodiments of the present invention have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms.

[0057] <Fourth Embodiment> In the first embodiment described above, the centrifugal clutch means 9 was located on the opening side (right side in Figure 2) of the clutch housing 2, but is not limited to this. For example, in the power transmission device 400K according to the fourth embodiment, as shown in Figures 30 to 32, the centrifugal clutch means 9 may be located on the bottom side (left side in Figure 30) of the clutch housing 2. The centrifugal clutch means 9 is located on the opposite side of the pressure member 5, sandwiching the drive-side clutch plate 6 and the driven-side clutch plate 7. Here, the centrifugal clutch means 9 is located on the side of the direction of arrow DR2 in Figure 30, more specifically, on the side of the clutch member 4 (more specifically, the second clutch member 4b).

[0058] <Fifth Embodiment> In the second embodiment described above, the centrifugal clutch means 209 was located on the opening side (right side in Figure 21) of the clutch housing 2, but is not limited thereto. For example, in the power transmission device 500K according to the fifth embodiment, as shown in Figures 33 to 35, the centrifugal clutch means 209 may be located on the bottom side (left side in Figure 33) of the clutch housing 2. The centrifugal clutch means 209 is located on the opposite side of the pressure member 5, sandwiching the drive-side clutch plate 6 and the driven-side clutch plate 7. Here, the centrifugal clutch means 209 is located on the side of the direction of arrow DR2 in Figure 33, more specifically, on the side of the clutch member 4 (more specifically, the second clutch member 4b).

[0059] <Sixth Embodiment> In the third embodiment described above, the centrifugal clutch means 309 was located on the opening side (right side in Figure 27) of the clutch housing 2, but is not limited thereto. For example, in the power transmission device 600K according to the sixth embodiment, as shown in Figures 36 to 38, the centrifugal clutch means 309 may be located on the bottom side (left side in Figure 36) of the clutch housing 2. The centrifugal clutch means 309 is located on the opposite side of the pressure member 5, sandwiching the drive-side clutch plate 6 and the driven-side clutch plate 7. Here, the centrifugal clutch means 309 is located on the side of the direction of arrow DR2 in Figure 36, more specifically, on the side of the clutch member 4 (more specifically, the second clutch member 4b).

[0060] In the embodiments described above, the centrifugal clutch means 9 had a first gradient surface 10a and a second gradient surface 10b on the weight member side cam surface K1, and a first gradient surface 12a and a second gradient surface 12b on the pressure contact member side cam surface K2, but is not limited thereto. The centrifugal clutch means 9 may have a first gradient surface 10a and a second gradient surface 10b on the weight member side cam surface K1, but may not have a first gradient surface 12a and a second gradient surface 12b on the pressure contact member side cam surface K2. Alternatively, the centrifugal clutch means 9 may not have a first gradient surface 10a and a second gradient surface 10b on the weight member side cam surface K1, but may have a first gradient surface 12a and a second gradient surface 12b on the pressure contact member side cam surface K2.

[0061] In the embodiments described above, the first gradient surface 10a, the second gradient surface 10b, the first gradient surface 12a, and the second gradient surface 12b were all planar, but they may also be curved surfaces. Furthermore, if at least one of the first gradient surface 10a and the second gradient surface 10b is a curved surface, it is preferable that it be convex outward (for example, in the direction of arrow DR2 in Figure 14). If at least one of the first gradient surface 12a and the second gradient surface 12b is a curved surface, it is preferable that it be convex outward (for example, in the direction of arrow DR1 in Figure 14).

[0062] In the embodiment described above, the weight member 10 had a first gradient surface 10a and a second gradient surface 10b on the weight member side cam surface K1, the gradient angle with respect to the axial direction of the output shaft 3 being larger than that of the first gradient surface 10a, but is not limited thereto. The weight member 10 may also have a third gradient surface radially outward from the first gradient surface 10a, the gradient angle with respect to the axial direction of the output shaft 3 being smaller than that of the first gradient surface 10a. Furthermore, the weight member 10 may also have a fourth gradient surface radially inward from the second gradient surface 10b, the gradient angle with respect to the axial direction of the output shaft 3 being larger than that of the second gradient surface 10b.

[0063] In the embodiment described above, the contact member 12 had a first gradient surface 12a and a second gradient surface 12b on the cam surface K2 on the contact member side, the gradient angle with respect to the axial direction of the output shaft 3 being larger than that of the first gradient surface 12a, but is not limited to this. The contact member 12 may also have a third gradient surface radially inward from the first gradient surface 12a, the gradient angle with respect to the axial direction of the output shaft 3 being smaller than that of the first gradient surface 12a. Furthermore, the contact member 12 may also have a fourth gradient surface radially outward from the second gradient surface 12b, the gradient angle with respect to the axial direction of the output shaft 3 being larger than that of the second gradient surface 12b.

[0064] In the embodiment described above, the contact member 15 had a first gradient surface 15a and a second gradient surface 15b on the cam surface 200K2 on the contact member side, the gradient angle with respect to the axial direction of the output shaft 3 being larger than that of the first gradient surface 15a, but is not limited to this. The contact member 15 may also have a third gradient surface radially inward from the first gradient surface 15a, the gradient angle with respect to the axial direction of the output shaft 3 being smaller than that of the first gradient surface 15a. Furthermore, the contact member 15 may also have a fourth gradient surface radially outward from the second gradient surface 15b, the gradient angle with respect to the axial direction of the output shaft 3 being larger than that of the second gradient surface 15b.

[0065] In the embodiment described above, all driven clutch plates 7 were held by the clutch member 4 (for example, the second clutch member 4b), but the embodiment is not limited to this. For example, a portion of the driven clutch plates 7 may be held by the clutch member 4 (for example, the second clutch member 4b), and another portion of the driven clutch plates 7 may be held by the pressure member 5. In this case, the other portion of the driven clutch plates 7 is configured to be movable along the axial direction of the pressure member 5 (i.e., the axial direction of the output shaft 3) and to rotate integrally with the pressure member 5.

[0066] In the embodiments described above, an engine E was used as the drive source, but the drive source is not limited to an engine E and may be an electric motor or the like.

[0067] The power transmission devices of each embodiment described above can be applied to various multi-plate clutch type power transmission devices in motorcycles, automobiles, three-wheeled or four-wheeled buggies, or general-purpose machines. [Explanation of symbols]

[0068] 1. Input gear (input component) 2 Clutch Housing 3. Output shaft (output component) 4. Clutch component 4a First clutch member 4b Second clutch member 5. Pressure Member 6. Drive-side clutch plate 7. Passed clutch plate 9. Centrifugal clutch mechanism 10 Weight Member 10a First gradient surface 10b Second Gradient Surface 11 Retaining member 12. Pressure-welded member 12a First gradient surface 12b Second Gradient Surface 14 Weight Member 14a Spherical member (contact portion) 15. Pressure-welded member 15a First gradient surface 15b Second Gradient Surface 16 Weight Member 16a, 16b Rolling members (contact parts) K Power transmission device K1 Weight member side cam surface K2 Cam surface on the side of the pressure-welding member

Claims

1. A clutch member that rotates together with an input member that rotates with the driving force of a drive source, is housed in a clutch housing that holds a plurality of drive-side clutch plates, and is connected to an output member capable of rotating a wheel, A plurality of driven clutch plates and a pressure member capable of pressing the plurality of driven clutch plates are provided so as to be able to approach or move away from the clutch member and are arranged alternately with the drive clutch plates, The clutch housing comprises a weight member that is movable from an inner diameter position to an outer diameter position by centrifugal force accompanying the rotation of the clutch housing, and a pressure contact member provided so as to be in contact with the weight member and which moves in a direction that presses the drive-side clutch plate and the driven-side clutch plate together as the weight member moves from the inner diameter position to the outer diameter position, and a centrifugal clutch means that presses the drive-side clutch plate and the driven-side clutch plate together when the weight member is in the outer diameter position to enable the transmission of the driving force of the drive source to the wheel, and releases the pressure between the drive-side clutch plate and the driven-side clutch plate when the weight member is in the inner diameter position to block the transmission of the driving force of the drive source to the wheel. The weight member is configured to press against the drive-side clutch plate and the driven-side clutch plate via the pressure contact member during the process of the weight member moving from the inner diameter side position to the outer diameter side position. The centrifugal clutch means has a first gradient surface and a second gradient surface having a greater gradient angle with respect to the axial direction of the output member than the first gradient surface, at the portion of the weight member that contacts the pressure contact member. The first gradient surface is formed in continuity with the second gradient surface or connected via a curved surface, and is located radially outward from the second gradient surface. A power transmission device in which, as the rotational speed of the drive source increases, the weight member and the pressure contact member come into contact with each other on the first gradient surface and then on the second gradient surface.

2. The power transmission device according to claim 1, wherein the first gradient surface and the second gradient surface are connected via a curved surface.

3. The power transmission device according to claim 1, wherein, in the process of increasing the rotational speed of the drive source, the rotational speed of the drive source is lower than the rotational speed at which the drive-side clutch plate and the driven-side clutch plate begin to press against each other, and the weight member and the press-fit member come into contact with each other on the first gradient surface and then come into contact with each other on the second gradient surface.

4. The power transmission device according to claim 1, wherein, in the process of increasing the rotational speed of the drive source, the rotational speed of the drive source is lower than the rotational speed at which the press contact between the drive-side clutch plate and the driven-side clutch plate is completed, and the weight member and the press contact member come into contact with each other on the first gradient surface and then come into contact with each other on the second gradient surface.

5. The centrifugal clutch means has a holding member that holds the weight member so that it can move between the inner diameter side position and the outer diameter side position. The weight member has a sliding surface that can slide against the holding member, The weight member has the first gradient surface and the second gradient surface, The power transmission device according to claim 1, wherein the pressure-welding member has a first gradient surface on the pressure-welding member side provided so as to be in contact with the first gradient surface at the portion where the weight member and the pressure-welding member come into contact, and a second gradient surface on the pressure-welding member side provided so as to be in contact with the second gradient surface, and the gradient angle with respect to the axial direction of the output member is greater than that of the first gradient surface on the pressure-welding member side.

6. The centrifugal clutch means has a holding member that holds the weight member so that it can move between the inner diameter side position and the outer diameter side position. The weight member has a contact portion that is in point contact with the holding member or is movable while rolling, The power transmission device according to claim 1, wherein the pressure-welding member has a first gradient surface on the pressure-welding member side provided so as to be in contact with the first gradient surface at the portion where the weight member and the pressure-welding member come into contact, and a second gradient surface on the pressure-welding member side provided so as to be in contact with the second gradient surface, and the gradient angle with respect to the axial direction of the output member is greater than that of the first gradient surface on the pressure-welding member side.

7. A clutch member that rotates together with an input member that rotates with the driving force of a drive source, is housed in a clutch housing that holds a plurality of drive-side clutch plates, and is connected to an output member capable of rotating a wheel, A plurality of driven clutch plates and a pressure member capable of pressing the plurality of driven clutch plates are provided so as to be able to approach or move away from the clutch member and are arranged alternately with the drive clutch plates, The clutch housing comprises a weight member that is movable from an inner diameter position to an outer diameter position by centrifugal force accompanying the rotation of the clutch housing, and a pressure contact member provided so as to be in contact with the weight member and which moves in a direction that presses the drive-side clutch plate and the driven-side clutch plate together as the weight member moves from the inner diameter position to the outer diameter position, and a centrifugal clutch means that presses the drive-side clutch plate and the driven-side clutch plate together when the weight member is in the outer diameter position to enable the transmission of the driving force of the drive source to the wheel, and releases the pressure between the drive-side clutch plate and the driven-side clutch plate when the weight member is in the inner diameter position to block the transmission of the driving force of the drive source to the wheel. The weight member is configured to press against the drive-side clutch plate and the driven-side clutch plate via the pressure contact member during the process of the weight member moving from the inner diameter side position to the outer diameter side position. The centrifugal clutch means has a first gradient surface and a second gradient surface having a greater gradient angle with respect to the axial direction of the output member than the first gradient surface, at the portion of the weight member that contacts the pressure contact member. The first gradient surface is formed in continuity with the second gradient surface or connected via a curved surface, and is located radially outward from the second gradient surface. When the weight member moves a predetermined distance in the radial direction, the amount of axial movement of the output member of the pressure contact member on the second gradient surface is smaller than the amount of axial movement of the pressure contact member on the first gradient surface. A power transmission device in which, as the rotational speed of the drive source increases, the weight member and the pressure contact member come into contact with each other on the first gradient surface and then on the second gradient surface.

8. The first gradient surface consists of a plane, The second gradient surface consists of a plane, The power transmission device according to claim 7, wherein the weight member and the pressure contact member are configured to be in contact with each other on the first gradient surface and the second gradient surface.

9. A clutch member that rotates together with an input member that rotates with the driving force of a drive source, is housed in a clutch housing that holds a plurality of drive-side clutch plates, and is connected to an output member capable of rotating a wheel, A plurality of driven clutch plates and a pressure member capable of pressing the plurality of driven clutch plates are provided so as to be able to approach or move away from the clutch member and are arranged alternately with the drive clutch plates, The clutch housing comprises a weight member that is movable from an inner diameter position to an outer diameter position by centrifugal force accompanying the rotation of the clutch housing, and a pressure contact member provided so as to be in contact with the weight member and which moves in a direction that presses the drive-side clutch plate and the driven-side clutch plate together as the weight member moves from the inner diameter position to the outer diameter position, and a centrifugal clutch means that presses the drive-side clutch plate and the driven-side clutch plate together when the weight member is in the outer diameter position to enable the transmission of the driving force of the drive source to the wheel, and releases the pressure between the drive-side clutch plate and the driven-side clutch plate when the weight member is in the inner diameter position to block the transmission of the driving force of the drive source to the wheel. The weight member is configured to press against the drive-side clutch plate and the driven-side clutch plate via the pressure contact member during the process of the weight member moving from the inner diameter side position to the outer diameter side position. The centrifugal clutch means has a first gradient surface and a second gradient surface having a greater gradient angle with respect to the axial direction of the output member than the first gradient surface, at the portion of the weight member that contacts the pressure contact member. The first gradient surface is formed in continuity with the second gradient surface or connected via a curved surface, and is located radially outward from the second gradient surface. The thrust of the weight member transmitted to the pressure-welding member on the second gradient surface is greater than the thrust of the weight member transmitted to the pressure-welding member on the first gradient surface. A power transmission device in which, as the rotational speed of the drive source increases, the weight member and the pressure contact member come into contact with each other on the first gradient surface and then on the second gradient surface.

10. The first gradient surface consists of a plane, The second gradient surface consists of a plane, The power transmission device according to claim 9, wherein the weight member and the pressure contact member are configured to be in contact with each other on the first gradient surface and the second gradient surface.

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