Patent Description:
Conventional vehicles such as motorcycles include clutch devices. A clutch device is disposed between an engine and a drive wheel and allows or interrupts transfer of a rotation driving force of the engine to the drive wheel. The clutch device generally includes a plurality of input-side rotating plates that rotate by a rotation driving force of an engine and a plurality of output-side rotating plates connected to an output shaft that transfers the rotation driving force to a drive wheel. The input-side rotating plates and the output-side rotating plates are alternately arranged in a stacking direction, and the input-side rotating plates and the output-side rotating plates are brought into pressure contact with each other and are separated from each other so that transfer of a rotation driving force is allowed or interrupted.

<CIT> discloses a power transmission device for motorcycles comprising a clutch housing, a clutch member, and a pressure member. It includes pressure-contact assisting and back torque limiter cams formed by respective cam surfaces on the clutch and pressure members. <CIT> further describes receiving members, separate from the pressure member, which interact with biasing means to adjust contact pressures and improve assembly precision, while reducing noise and vibration.

<CIT> discloses a clutch device comprising a center clutch and a pressure clutch, each provided with cam surfaces for assisting or slipping during torque transmission. To improve alignment and ensure stable torque transmission, <CIT> further provides a dual guidance structure with differential clearances, allowing controlled tilting of the pressure clutch. The device is typically used in motorcycles and operates as a wet multi-plate clutch with enhanced engagement and disengagement characteristics.

<CIT>, for example, discloses a clutch device including a clutch center (clutch member) that holds output-side rotating plates (driven-side clutch plates), and a pressure plate (pressure member) movable toward or away from the clutch center. The pressure plate is configured to press the input-side rotating plates and the output-side rotating plates. In this manner, the clutch device includes an assembly of the clutch center and the pressure plate.

In the clutch device of <CIT>, as portions holding the output-side rotating plates, the clutch center includes center-side fitting teeth (outer peripheral wall including splines), and the pressure plate includes pressure-side fitting teeth. In a state where the clutch center and the pressure plate are assembled, the center-side fitting teeth and the pressure-side fitting teeth overlap with each other in the radial direction.

When the pressure plate is separated from the clutch center, a gap can be formed between the pressure-side fitting teeth and the center-side fitting teeth in the direction in which the pressure plate moves (i.e., axial direction of the output shaft). In this case, for example, clutch oil flowing in the clutch center flows to the outside through the gap, and thus, clutch oil does not easily flow to the output-side rotating plates held by the pressure plate, disadvantageously.

The object of the present invention is to provide a clutch device capable of supplying a larger amount of clutch oil to output-side rotating plates held by pressure-side fitting teeth of a pressure plate.

According to the present invention, this object is achieved by a clutch device as defined in independent claim <NUM>.

In particular, a clutch device according to the present invention is a clutch device to allow or interrupt transfer of a rotation driving force of an input shaft to an output shaft, and comprises a clutch center housed in a clutch housing holding a plurality of input-side rotating plates to be rotationally driven by rotational driving of the input shaft, the clutch center being operable to hold a plurality of output-side rotating plates and to be rotationally driven together with the output shaft, the input-side rotating plates and the output-side rotating plates being alternately arranged, a pressure plate movable toward or away from the clutch center and rotatable relative to the clutch center to press the input-side rotating plates and the output-side rotating plates, and a stopper plate operable to contact the pressure plate and to suppress separation of the pressure plate from the clutch center by a predetermined distance or more, wherein the clutch center includes a boss extending toward the pressure plate, the stopper plate is fixed to the boss, the pressure plate includes a plurality of pressure-side fitting teeth holding at least one of the output-side rotating plates and arranged in circumferential directions, the clutch center includes an output shaft holding portion to which the output shaft is coupled, an outer peripheral wall located radially outward of the output shaft holding portion, and a plurality of center-side fitting teeth holding the output-side rotating plates, projecting radially outward from an outer peripheral surface of the outer peripheral wall, and arranged in circumferential directions, and in a state where the pressure plate is in contact with the stopper plate, a portion of one of the center-side fitting teeth overlap with a portion of one of the pressure-side fitting teeth when seen in radial directions of the output shaft.

Preferred embodiments of the present invention provide clutch devices each capable of supplying a larger amount of clutch oil to output-side rotating plates held by pressure-side fitting teeth of a pressure plate.

Clutch devices according to preferred embodiments of the present disclosure will be described hereinafter with reference to the drawings. The preferred embodiments described herein are, of course, not intended to particularly limit the present disclosure. Elements and features having the same functions are denoted by the same reference characters, and description for the same elements and features will not be repeated or will be simplified as appropriate.

<FIG> is a cross-sectional view of a clutch device <NUM> according to this preferred embodiment. The clutch device <NUM> is provided in a vehicle such as a motorcycle, for example. The clutch device <NUM> allows or interrupts transfer of a rotation driving force of an input shaft (crankshaft) of an engine of the motorcycle to an output shaft <NUM>, for example. The clutch device <NUM> allows or interrupts transfer of a rotation driving force of the input shaft to a drive wheel (rear wheel) through the output shaft <NUM>. The clutch device <NUM> is disposed between the engine and a transmission.

In the following description, directions in which a pressure plate <NUM> of the clutch device <NUM> is movable toward and away from the clutch center <NUM> will be referred to as directions D (an example of a movement direction), a direction in which the pressure plate <NUM> moves toward the clutch center <NUM> will be referred to as a first direction D1, and a direction in which the pressure plate <NUM> is movable away from the clutch center <NUM> will be referred to as a second direction D2. Circumferential directions of the clutch center <NUM> and the pressure plate <NUM> will be referred to as circumferential directions S, one of the circumferential direction S from one pressure-side cam portion <NUM> to another pressure-side cam portion <NUM> will be referred to as a first circumferential direction S1 (see <FIG>), and one of the circumferential direction S from the other pressure-side cam portion <NUM> to the one pressure-side cam portion <NUM> will be referred to as a second circumferential direction S2 (see <FIG>). In this preferred embodiment, axial directions of the output shaft <NUM>, axial directions of a clutch housing <NUM>, axial directions of the clutch center <NUM>, and axial directions of the pressure plate <NUM> are the same as the directions D. The pressure plate <NUM> and the clutch center <NUM> rotate in the first circumferential direction S1. It should be noted that the directions described above are defined simply for convenience of description, and are not intended to limit the state of installation of the clutch device <NUM> and do not limit the present disclosure.

As illustrated in <FIG>, the clutch device <NUM> includes the output shaft <NUM>, input-side rotating plates <NUM>, output-side rotating plates <NUM>, the clutch housing <NUM>, the clutch center <NUM>, the pressure plate <NUM>, and a stopper plate <NUM>.

As illustrated in <FIG>, the output shaft <NUM> is a hollow shaft. One end of the output shaft <NUM> rotatably supports an input gear <NUM> described later and the clutch housing <NUM> through a needle bearing 15A. The output shaft <NUM> fixedly supports a clutch center <NUM> through a nut 15B. That is, the output shaft <NUM> rotates together with the clutch center <NUM>. The other end of the output shaft <NUM> is coupled to a transmission (not shown) of an automobile, for example.

As illustrated in <FIG>, the output shaft <NUM> includes, in a hollow portion <NUM> thereof, a push rod 16A and a push member 16B adjacent to the push rod 16A. The hollow portion <NUM> serves as a channel of clutch oil. Clutch oil flows in the output shaft <NUM>, that is, in the hollow portion <NUM>. The push rod 16A and the push member 16B are slidable in the hollow portion <NUM> of the output shaft <NUM>. The push rod 16A has one end (left end in the drawing) coupled to a clutch operation lever (not shown) of the motorcycle, and slides in the hollow portion <NUM> by operation of the clutch operation lever and presses the clutch push member 16B in the second direction D2. A portion of the push member 16B projects outward of the output shaft <NUM> (in the second direction D2 in this preferred embodiment) and is coupled to a release bearing <NUM> provided on the pressure plate <NUM>. The push rod 16A and the push member 16B are thinner than the inner diameter of the hollow portion <NUM> so that flowability of clutch oil is obtained in the hollow portion <NUM>.

The clutch housing <NUM> is made of an aluminum alloy. The clutch housing <NUM> has a bottomed cylindrical shape. As illustrated in <FIG>, the clutch housing <NUM> includes a bottom wall <NUM> having a substantially circular shape, and a side wall <NUM> extending from an edge of the bottom wall <NUM> in the second direction D2. The clutch housing <NUM> holds the plurality of input-side rotating plates <NUM>.

As illustrated in <FIG>, an input gear <NUM> is disposed on the bottom wall <NUM> of the clutch housing <NUM>. The input gear <NUM> is fixed to the bottom wall <NUM> by a rivet 35B through a torque damper 35A. The input gear <NUM> meshes with a driving gear (not shown) that rotates by rotational driving of the input shaft of the engine. The input gear <NUM> is rotationally driven together with the clutch housing <NUM>, independently of the output shaft <NUM>.

The input-side rotating plates <NUM> are rotationally driven by rotational driving of the input shaft. As illustrated in <FIG>, the input-side rotating plates <NUM> are held on the inner peripheral surface of the side wall <NUM> of the clutch housing <NUM>. The input-side rotating plates <NUM> are held in the clutch housing <NUM> by spline fitting. The input-side rotating plates <NUM> are displaceable along the axial direction of the clutch housing <NUM>. The input-side rotating plates <NUM> are rotatable together with the clutch housing <NUM>.

The input-side rotating plates <NUM> are pushed against the output-side rotating plates <NUM>. The input-side rotating plates <NUM> are ring-shaped flat plates. Each of the input-side rotating plates <NUM> is shaped by punching a thin plate of a steel plate cold commercial (SPCC) material into a ring shape. Friction members (not shown) of a plurality of paper sheets are attached to the front and back surfaces of the input-side rotating plates <NUM>. A groove with a depth of several micrometers to several tens of micrometers is formed between the friction members to hold clutch oil.

As illustrated in <FIG>, the clutch center <NUM> is housed in the clutch housing <NUM>. The clutch center <NUM> and the clutch housing <NUM> are concentrically disposed. The clutch center <NUM> includes a cylindrical body <NUM> and a flange <NUM> extending radially outward from the outer edge of the body <NUM>. The clutch center <NUM> holds the plurality of output-side rotating plates <NUM> arranged alternately with the input-side rotating plates <NUM> in the directions D. The clutch center <NUM> is rotationally driven together with the output shaft <NUM>.

As illustrated in <FIG>, the body <NUM> includes a ring-shaped base wall <NUM>, an outer peripheral wall <NUM> located radially outward of the base wall <NUM> and extending in the second direction D2, an output shaft holding portion <NUM> disposed at the center of the base wall <NUM>, a plurality of center-side cam portions <NUM> connected to the base wall <NUM> and the outer peripheral wall <NUM>, and a center-side fitting portion <NUM>.

The output shaft holding portion <NUM> has a cylindrical shape. The output shaft holding portion <NUM> has an insertion hole <NUM> in which the output shaft <NUM> is inserted and spline-fitted. The insertion hole <NUM> penetrates the base wall <NUM>. An inner peripheral surface 50A of the output shaft holding portion <NUM> defining the insertion hole <NUM> includes a plurality of spline grooves formed along the axial direction. The output shaft <NUM> is coupled to the output shaft holding portion <NUM>.

As illustrated in <FIG>, the outer peripheral wall <NUM> of the clutch center <NUM> is disposed radially outward of the output shaft holding portion <NUM>. The outer peripheral wall <NUM> is formed integrally with the output shaft holding portion <NUM>. The outer peripheral surface of the outer peripheral wall <NUM> includes a spline fitting portion <NUM>. The spline fitting portion <NUM> includes a plurality of center-side fitting teeth <NUM> extending in the axial directions of the clutch center <NUM> along the outer peripheral surface of the outer peripheral wall <NUM>, a plurality of spline grooves <NUM> each formed between adjacent ones of the center-side fitting teeth <NUM> and extending in the axial directions of the clutch center <NUM>, and oil flow holes <NUM>. The center-side fitting teeth <NUM> hold the output-side rotating plates <NUM>. The plurality of center-side fitting teeth <NUM> arranged in the circumferential directions S. The plurality of center-side fitting teeth <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S. The plurality of center-side fitting teeth <NUM> have the same or substantially the same shape. The center-side fitting teeth <NUM> project radially outward from the outer peripheral surface of the outer peripheral wall <NUM>. The outer peripheral surfaces of the center-side fitting teeth <NUM> are approximately in parallel with the axis of the output shaft <NUM>. As illustrated in <FIG>, the oil flow holes <NUM> penetrate the outer peripheral wall <NUM> along the radial directions. Each of the oil flow holes <NUM> is formed between adjacent ones of the center-side fitting teeth <NUM>. That is, the oil flow holes <NUM> are formed in the spline grooves <NUM>. The oil flow holes <NUM> are formed at the sides of the center-side cam portions <NUM>. More specifically, the discharge holes <NUM> are formed at the sides of the center-side slipper cam surfaces <NUM> of the center-side cam portions <NUM>. The oil flow holes <NUM> are located ahead of the center-side slipper cam surface <NUM> in the first circumferential direction S1. The oil flow holes <NUM> are located ahead of bosses <NUM> described later in the second circumferential direction S2. The oil flow holes <NUM> cause the inside and outside of the clutch center <NUM> to communicate with each other. The oil flow holes <NUM> allow clutch oil that has flowed from the output shaft <NUM> into the clutch center <NUM> to be discharged to the outside of the clutch center <NUM>.

The output-side rotating plates <NUM> are held by the spline fitting portion <NUM> of the clutch center <NUM> and the pressure plate <NUM>. A portion of the output-side rotating plates <NUM> is held by the center-side fitting teeth <NUM> of the clutch center <NUM> and the spline grooves <NUM> by spline fitting. Another portion of the output-side rotating plates <NUM> is held by a pressure-side fitting teeth <NUM> (see <FIG>) described later of the pressure plate <NUM>. The output-side rotating plates <NUM> are displaceable along the axial directions of the clutch center <NUM>. The output-side rotating plates <NUM> are rotatable together with the clutch center <NUM>.

The output-side rotating plates <NUM> are pushed against the input-side rotating plates <NUM>. The output-side rotating plates <NUM> are ring-shaped flat plates. Each of the output-side rotating plates <NUM> is shaped by punching a thin plate of an SPCC material into a ring shape. The front and back surfaces of the output-side rotating plates <NUM> have grooves with depths of several micrometers to several tens of micrometers, for example, to hold clutch oil. The front and back surfaces of the output-side rotating plates <NUM> are subjected to a surface hardening treatment to enhance abrasion resistance. The friction members provided on the input-side rotating plates <NUM> may be provided on the output-side rotating plates <NUM> instead of the input-side rotating plates <NUM>, or may be provided on both the input-side rotating plates <NUM> and the output-side rotating plates <NUM>.

Each of the center-side cam portions <NUM> has a trapezoidal shape including a cam surface of a slope defining an assist & slipper (registered trademark) mechanism that generates an assist torque as a force of increasing a pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> or a slipper torque as a force of separating the input-side rotating plates <NUM> and the output-side rotating plates <NUM> from each other early and shifting these plates into a half-clutch state. The center-side cam portions <NUM> project from the base wall <NUM> in the second direction D2. As illustrated in <FIG>, the center-side cam portions <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S of the clutch center <NUM>. In this preferred embodiment, the clutch center <NUM> includes three center-side cam portions <NUM>, but the number of the center-side cam portions <NUM> is not limited to three.

As illustrated in <FIG>, the center-side cam portions <NUM> are located radially outward of the output shaft holding portion <NUM>. Each of the center-side cam portions <NUM> includes the center-side assist cam surface 60A and the center-side slipper cam surface <NUM>. The center-side assist cam surface 60A is configured to generate a force in a direction in which the pressure plate <NUM> approaches the clutch center <NUM> in order to increase a pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> in relative rotation to the pressure plate <NUM>. In this preferred embodiment, when this force is generated, the position of the pressure plate <NUM> to the clutch center <NUM> does not change, and the pressure plate <NUM> does not need to approach the clutch center <NUM> physically. The pressure plate <NUM> may be physically displaced with respect to the clutch center <NUM>. The center-side slipper cam surface <NUM> is configured to separate the pressure plate <NUM> from the clutch center <NUM> in order to reduce the pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> in relative rotation to the pressure plate <NUM>. In the center-side cam portions <NUM> adjacent to each other in the circumferential directions S, the center-side assist cam surface 60A of one center-side cam portion <NUM> and the center-side slipper cam surface <NUM> of the other center-side cam portion <NUM> are opposed to each other in the circumferential directions S.

As illustrated in <FIG>, the clutch center <NUM> includes the plurality of (for example, three in this preferred embodiment) bosses <NUM>. The bosses <NUM> support the pressure plate <NUM>. The plurality of bosses <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S. Each of the bosses <NUM> has a cylindrical shape. The bosses <NUM> are located radially outward of the output shaft holding portion <NUM>. The bosses <NUM> extend toward the pressure plate <NUM> (i.e., in the second direction D2). The bosses <NUM> are disposed on the base wall <NUM>. The bosses <NUM> have screw holes <NUM> in which bolts <NUM> (see <FIG>) are inserted. The screw holes <NUM> extend in the axial directions of the clutch center <NUM>.

As illustrated in <FIG>, the center-side fitting portion <NUM> is located radially outward of the output shaft holding portion <NUM>. The center-side fitting portion <NUM> is located radially outward of the center-side cam portions <NUM>. The center-side fitting portion <NUM> is disposed ahead of the center-side cam portions <NUM> in the second direction D2. The center-side fitting portion <NUM> is formed on the inner peripheral surface of the outer peripheral wall <NUM>. The center-side fitting portion <NUM> is slidably fitted onto a pressure-side fitting portion <NUM> (see <FIG>) described later. The inner diameter of the center-side fitting portion <NUM> has a fitting tolerance allowing distribution of clutch oil flowing out of a distal end 15T of the output shaft <NUM> to the pressure-side fitting portion <NUM>. That is, a gap is formed between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM> described later. In this preferred embodiment, for example, the center-side fitting portion <NUM> has an inner diameter larger than the outer diameter of the pressure-side fitting portion <NUM> by about <NUM>. This dimensional tolerance between the inner diameter of the center-side fitting portion <NUM> and the outer diameter of the pressure-side fitting portion <NUM> is appropriately set in accordance with the amount of clutch oil intended to be distributed, and is, for example, about <NUM> or more and about <NUM> or less.

As illustrated in <FIG> and <FIG>, the clutch center <NUM> includes the center-side cam holes <NUM> penetrating a portion of the base wall <NUM>. The center-side cam holes <NUM> extend from portions on the side of the output shaft holding portion <NUM> to the outer peripheral wall <NUM>. Each center-side cam hole <NUM> is formed between the center-side assist cam surface 60A of the center-side cam portion <NUM> and the boss <NUM>. When seen in the axial direction of the clutch center <NUM>, the center-side assist cam surface 60A overlaps with a portion of the center-side cam hole <NUM>.

As illustrated in <FIG>, the pressure plate <NUM> is movable toward or away from the clutch center <NUM> and rotatable relative to the clutch center <NUM>. The pressure plate <NUM> is configured to press the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. The pressure plate <NUM> is disposed coaxially with the clutch center <NUM> and the clutch housing <NUM>. The pressure plate <NUM> includes a body <NUM>, and a flange <NUM> connected to the outer edge of the body <NUM> on the side of the second direction D2 and extending radially outward. The body <NUM> projects ahead of the flange <NUM> in the first direction D1. The flange <NUM> is located at the outer diameter end of the pressure plate <NUM>. The flange <NUM> is located radially outward of a cylindrical portion <NUM> (see <FIG>) described later. The pressure plate <NUM> holds the plurality of output-side rotating plates <NUM> arranged alternately with the input-side rotating plates <NUM>. The flange <NUM> is configured to press the input-side rotating plates <NUM> and the output-side rotating plates <NUM>.

As illustrated in <FIG>, the body <NUM> includes the cylindrical portion <NUM>, the plurality of pressure-side cam portions <NUM>, the pressure-side fitting portion <NUM>, and a spring housing portion <NUM> (see also <FIG>).

The cylindrical portion <NUM> has a cylindrical shape. The cylindrical portion <NUM> is integrally formed with the pressure-side cam portions <NUM>. The cylindrical portion <NUM> houses the distal end 15T of the output shaft <NUM> (see <FIG>). The cylindrical portion <NUM> houses the release bearing <NUM> (see <FIG>). The cylindrical portion <NUM> receives a pressing force from the push member 16B. The cylindrical portion <NUM> receives clutch oil that has flowed out from the distal end 15T of the output shaft <NUM>.

Each of the pressure-side cam portions <NUM> is formed in a trapezoidal shape having a cam surface of a slope constituting an assist & slipper (registered trademark) mechanism that slides on the center-side cam portions <NUM> and generates an assist torque or a slipper torque. The pressure-side cam portions <NUM> project from the flange <NUM> in the first direction D1. As illustrated in <FIG>, the pressure-side cam portions <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S of the pressure plate <NUM>. In this preferred embodiment, the pressure plate <NUM> includes three pressure-side cam portions <NUM>, but the number of the pressure-side cam portions <NUM> is not limited to three.

As illustrated in <FIG>, the pressure-side cam portion <NUM> is located radially outward of the cylindrical portion <NUM>. Each of the pressure-side cam portions <NUM> includes a pressure-side assist cam surface 90A (see also <FIG> and <FIG>) and a pressure-side slipper cam surface <NUM>. The pressure-side assist cam surface 90A can be brought into contact with the center-side assist cam surface 60A. The pressure-side assist cam surface 90A is configured to generate a force in a direction in which the pressure plate <NUM> approaches the clutch center <NUM> in order to increase a pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> in relative rotation to the clutch center <NUM>. The pressure-side slipper cam surface <NUM> can be brought into contact with the center-side slipper cam surface <NUM>. The pressure-side slipper cam surface <NUM> is configured to separate the pressure plate <NUM> from the clutch center <NUM> in order to reduce a pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> in relative rotation to the clutch center <NUM>. In the pressure-side cam portions <NUM> adjacent to each other in the circumferential directions S, the pressure-side assist cam surface 90A of one pressure-side cam portion <NUM> and the pressure-side slipper cam surface <NUM> of the other pressure-side cam portion <NUM> are opposed to each other in the circumferential directions S.

As illustrated in <FIG>, an end of the pressure-side assist cam surface 90A of each pressure-side cam portion <NUM> in the circumferential directions S includes a chamfered portion 90AP that is linearly chamfered. A corner of the chamfered portion 90AP (corner on the side of the first direction D1 and the first circumferential direction S1) includes a right angle. More specifically, the chamfered portion 90AP is formed in an end 90AB of the pressure-side assist cam surface 90A in the first circumferential direction S1.

Advantages of the center-side cam portions <NUM> and the pressure-side cam portions <NUM> will now be described. When the rotation speed of the engine increases so that a rotation driving force input to the input gear <NUM> and the clutch housing <NUM> is thereby allowed to be transferred to the output shaft <NUM> through the clutch center <NUM>, a rotation force in the first circumferential direction S1 is applied to the pressure plate <NUM>, as illustrated in <FIG>. Thus, with the effects of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, a force in first direction D1 is generated in the pressure plate <NUM>. Accordingly, the pressure plate <NUM> further moves in the direction toward the clutch center <NUM> (first direction D1) to increase a pressure contact force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM>.

On the other hand, when the rotation speed of the output shaft <NUM> exceeds the rotation speed of the input gear <NUM> and the clutch housing <NUM> and a back torque is generated, a rotation force in the first circumferential direction S1 is applied to the clutch center <NUM>, as illustrated in <FIG>. Thus, with the effects of the center-side slipper cam surface <NUM> and the pressure-side slipper cam surface <NUM>, the pressure plate <NUM> moves in the second direction D2 and releases a contact pressure force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. In this manner, it is possible to avoid problems in the engine and the transmission caused by the back torque.

As illustrated in <FIG>, the pressure-side fitting portion <NUM> is located radially outside of the pressure-side cam portions <NUM>. The pressure-side fitting portion <NUM> is located ahead of the pressure-side cam portions <NUM> in the second direction D2. The pressure-side fitting portion <NUM> is configured to slidably fit in the center-side fitting portion <NUM> (see <FIG>).

As illustrated in <FIG> and <FIG>, the pressure plate <NUM> includes pressure-side cam holes <NUM> penetrating the body <NUM> and a portion of the flange <NUM>. The pressure-side cam holes <NUM> are located radially outward of the cylindrical portion <NUM>. The pressure-side cam holes <NUM> extend from portions on the side of the cylindrical portion <NUM> to the radially outside of the pressure-side fitting portion <NUM>. Each of the pressure-side cam holes <NUM> is formed between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface <NUM> of adjacent ones of the pressure-side cam portions <NUM>. As illustrated in <FIG> and <FIG>, when seen in the axial direction of the pressure plate <NUM>, the pressure-side assist cam surface 90A overlaps with portions of the pressure-side cam holes <NUM>.

As illustrated in <FIG>, the pressure plate <NUM> includes the plurality of pressure-side fitting teeth <NUM> arranged on the surface 98A of the flange <NUM> facing in the first direction. The pressure-side fitting teeth <NUM> hold at least one of the output-side rotating plates <NUM>. The input-side rotating plates <NUM> and the output-side rotating plates <NUM> are movable in the directions D along outer peripheral surfaces 77A of the pressure-side fitting teeth <NUM> (see also <FIG>). The pressure-side fitting teeth <NUM> project in the first direction D1 from the surface 98A of the flange <NUM> facing in the first direction. The pressure-side fitting teeth <NUM> are located radially outward of the cylindrical portion <NUM>. The pressure-side fitting teeth <NUM> are located radially outward of the pressure-side cam portions <NUM>. The pressure-side fitting teeth <NUM> are located radially outward of the pressure-side fitting portion <NUM>. The plurality of pressure-side fitting teeth <NUM> are arranged in the circumferential directions S. The plurality of pressure-side fitting teeth <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S. As illustrated in <FIG>, a recess <NUM> that is recessed radially inward is formed at each end of the outer peripheral surfaces 77A of the pressure-side fitting teeth <NUM> in the second direction D2. The recess <NUM> is formed along the entire circumference of each end of the outer peripheral surfaces 77A of the pressure-side fitting teeth <NUM> in the second direction D2. A length RA of the recess <NUM> in the directions D is smaller than a length RB of one input-side rotating plate <NUM> in the directions D. Inner peripheral surfaces 77B of the pressure-side fitting teeth <NUM> tilt radially outward in the first direction D1. The inner peripheral surfaces 77B of the pressure-side fitting teeth <NUM> tilt by, for example, about <NUM>° with respect to the output shaft <NUM> such that the inner peripheral surfaces 77B gradually approach the radially outer side in the first direction D1. A tilt angle of the inner peripheral surfaces 77B is larger than a tilt angle of other portions, such as the outer peripheral surfaces 77A of the pressure-side fitting teeth <NUM>. The outer peripheral surfaces 77A of the pressure-side fitting teeth <NUM> tilt radially outward in the second direction D2. The outer peripheral surfaces 77A of the pressure-side fitting teeth <NUM> tilt by, for example, about <NUM>° with respect to the output shaft <NUM> such that the outer peripheral surfaces 77A gradually approach the radially outer side in the second direction D2. As illustrated in <FIG>, a pair of side surfaces 77F of each of the pressure-side fitting teeth <NUM> in the circumferential directions S tilt to approach each other in the first direction D1 when seen in the radial directions of the output shaft <NUM>. An angle α defined by each side surface 77F and a line <NUM> parallel to the axis of the output shaft <NUM> is, for example, larger than about <NUM>° and smaller than about <NUM>° (e.g., larger than about <NUM>° and smaller than about <NUM>°). In this preferred embodiment, since a portion of the pressure-side fitting teeth <NUM> has been removed, the interval of this portion is enlarged, but the other adjacent pressure-side fitting teeth <NUM> are arranged at regular or substantially regular intervals.

As illustrated in <FIG>, a length P1 of each of the pressure-side fitting teeth <NUM> in the directions D is larger than a total distance (P2 + P3) of the sum of a maximum movement distance P2 of the pressure plate <NUM> in the directions D and a rotating plate distance P3 that is a distance from an end 22AT of a pressure-side outermost output-side rotating plate 22A, which is one of the output-side rotating plates <NUM> held by the pressure-side fitting teeth <NUM> located at the front in the first direction D1, in the second direction D2 to an end 77Q (boundary with the flange <NUM>) of the pressure-side fitting tooth <NUM> in the second direction D2. That is, P1 > (P2 + P3) is established. The normal state means that the pressure plate <NUM> is closest to the clutch center <NUM>. The normal state herein refers to a state where the clutch is engaged (hereinafter referred to as a clutch ON state). Thus, as illustrated in <FIG>, when the pressure plate <NUM> moves from the normal state in the second direction D2 by the maximum movement distance P2, the pressure-side outermost output-side rotating plate 22A overlaps with a portion of the pressure-side fitting teeth <NUM>, and the pressure-side outermost output-side rotating plate 22A is held by the pressure-side fitting teeth <NUM>. That is, the pressure-side fitting teeth <NUM> always hold the pressure-side outermost output-side rotating plate 22A, and has the length P1 enough to prevent the pressure-side outermost output-side rotating plate 22A from dropping off. The rotating plate distance P3 may be a distance in the normal state from an end 22DT of the pressure-side outermost output-side rotating plate 22A in the first direction D1 to the end 77Q (boundary with the flange <NUM>) of the pressure-side fitting tooth <NUM> in the second direction D2. When the pressure plate <NUM> moves from the normal state in the second direction D2 by the maximum movement distance P2, the pressure plate <NUM> is brought into contact with the stopper plate <NUM> (see <FIG>). As illustrated in <FIG>, while the pressure plate <NUM> is farthest from the clutch center <NUM>, the input-side rotating plates <NUM> located ahead of the pressure-side outermost output-side rotating plate 22A in the first direction D1 do not overlap with the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 when seen in the radial directions of the output shaft <NUM>. That is, while the pressure plate <NUM> is farthest from the clutch center <NUM>, a member located at the front in the pressure-side fitting teeth <NUM> in the first direction D1 is the pressure-side outermost output-side rotating plate 22A. In this preferred embodiment, in attaching the pressure plate <NUM> to the clutch center <NUM> with the output-side rotating plates <NUM> held by the pressure-side fitting teeth <NUM>, since the output-side rotating plates <NUM> are held by the distal ends (i.e., the ends 77T in the first direction D1) of the pressure-side fitting teeth <NUM>, the output-side rotating plates <NUM> do not fall off from the pressure-side fitting teeth <NUM>. Accordingly, the pressure plate <NUM> is easily attached to the clutch center <NUM>. In addition, while the pressure plate <NUM> is farthest from the clutch center <NUM> (e.g., the pressure plate <NUM> is in contact with the stopper plate <NUM>, hereinafter referred to as an over-lift state), the input-side rotating plates <NUM> located ahead of the pressure-side outermost output-side rotating plate 22A in the first direction D1 do not overlap with the pressure-side fitting teeth <NUM> (i.e., the pressure-side fitting teeth <NUM> are short enough to avoid overlapping) when seen in the radial directions of the output shaft <NUM>. Thus, it is possible to prevent collision of the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 against the input-side rotating plates <NUM> held by the clutch center <NUM> when the clutch is engaged. Furthermore, since the pressure-side outermost output-side rotating plate 22A can be always held by the pressure-side fitting teeth <NUM> independently of the position of the pressure plate <NUM> with a compact size (i.e., short length) of the pressure-side fitting teeth <NUM>, it is possible to prevent the pressure-side outermost output-side rotating plate 22A from dropping off from the pressure-side fitting teeth <NUM>. On the other hand, in the over-lift state, if the input-side rotating plates <NUM> located ahead of the pressure-side outermost output-side rotating plate 22A in the first direction D1 overlap with the pressure-side fitting teeth <NUM> (i.e., the pressure-side fitting teeth <NUM> are long to allow overlapping) when seen in the radial directions of the output shaft <NUM>, the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 might collide with the input-side rotating plates <NUM> held by the clutch center <NUM> when the clutch is engaged.

As illustrated in <FIG>, the pressure-side fitting teeth <NUM> are located radially outward of the center-side fitting teeth <NUM>. A gap is formed between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM> in the radial directions. As illustrated in <FIG>, ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 are located ahead, in the first direction D1, of ends 47T of the center-side fitting teeth <NUM> in the second direction D2. A distance LX between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM> in the radial directions is longer than a distance LY between the pressure-side fitting portion <NUM> and the center-side fitting portion <NUM> in the radial directions. As described above, since the inner peripheral surfaces 77B of the pressure-side fitting teeth <NUM> tilt radially outward in the first direction D1 and the outer peripheral surfaces of the center-side fitting teeth <NUM> are substantially in parallel with the axis of the output shaft <NUM>, the distance LX gradually increases in the first direction D1. Accordingly, while the pressure plate <NUM> and the clutch center <NUM> rotate, clutch oil held in space between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM> is easily spattered to the output-side rotating plates <NUM> and the input-side rotating plates <NUM> from wide openings between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the center-side fitting teeth <NUM> so that lubricity between the output-side rotating plates <NUM> and the input-side rotating plates <NUM> increases. The distance LX is a shortest distance of the distances between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM> in the radial directions. In the normal state, a gap CX is formed between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and a center-side outermost output-side rotating plate 22B, which is one of the output-side rotating plates <NUM> held by the clutch center <NUM> located at the front in the second direction D2. That is, the pressure-side fitting teeth <NUM> are not in contact with the center-side outermost output-side rotating plate 22B.

As illustrated in <FIG> and <FIG>, the spring housing portions <NUM> are formed in the pressure-side cam portions <NUM>. The spring housing portions <NUM> are recessed from the second direction D2 to the first direction D1. Each of the spring housing portions <NUM> has an oval shape. The spring housing portions <NUM> house pressure springs <NUM> (see <FIG>). The spring housing portions <NUM> include the insertion holes <NUM> which penetrate the spring housing portions <NUM> and in which the bosses <NUM> (see <FIG>) are inserted. That is, the insertion holes <NUM> penetrate the pressure-side cam portions <NUM>. Each of the insertion holes <NUM> has an oval shape.

As illustrated in <FIG>, the pressure springs <NUM> are housed in the spring housing portions <NUM>. The pressure springs <NUM> are held by the bosses <NUM> inserted in the insertion holes <NUM> of the spring housing portions <NUM>. The pressure springs <NUM> bias the pressure plate <NUM> toward the clutch center <NUM> (i.e., in the first direction D1). The pressure springs <NUM> are, for example, coil springs obtained by helically winding spring steel.

<FIG> is a plan view illustrating a state where the clutch center <NUM> and the pressure plate <NUM> are combined. In the state illustrated in <FIG>, the pressure-side assist cam surface 90A and the center-side assist cam surface 60A do not contact each other, and the pressure-side slipper cam surface <NUM> and the center-side slipper cam surface <NUM> do not contact each other. At this time, the pressure plate <NUM> is closest to the clutch center <NUM>. This state will be referred to as a normal state of the clutch device <NUM>. As illustrated in <FIG>, a distance L5 in the circumferential directions S between the boss <NUM> and an end 84HA of the insertion holes <NUM> toward the pressure-side assist cam surface 90A (i.e., ahead in the first circumferential direction S1) in the normal state is smaller than a distance L6 in the circumferential direction S between the boss <NUM> and an end 84HB of the insertion holes <NUM> toward the pressure-side slipper cam surface <NUM> (i.e., ahead in the second circumferential direction S2) in the normal state.

As illustrated in <FIG>, the stopper plate <NUM> can contact the pressure plate <NUM>. The stopper plate <NUM> reduces or prevents separation of the pressure plate <NUM> from the clutch center <NUM> by a predetermined distance or more in the second direction D2. The stopper plate <NUM> is fixed to the bosses <NUM> of the clutch center <NUM> with the bolts <NUM>. The pressure plate <NUM> is fixed by fastening the bolts <NUM> to the bosses <NUM> through the stopper plate <NUM> with the bosses <NUM> and the pressure springs <NUM> of the clutch center <NUM> disposed in the spring housing portions <NUM>. The stopper plate <NUM> is substantially triangular in plan view.

When the pressure plate <NUM> is brought into contact with the stopper plate <NUM>, the pressure-side slipper cam surface <NUM> and the center-side slipper cam surface <NUM> are in contact with each other in an area of about <NUM>% or more and about <NUM>% or less of the area of the pressure-side slipper cam surface <NUM> and about <NUM>% or more and about <NUM>% or less of the area of the center-side slipper cam surface <NUM>, for example. When the pressure plate <NUM> is brought into contact with the stopper plate <NUM>, the pressure springs <NUM> are separated from the side walls of the spring housing portions <NUM>. That is, the pressure springs <NUM> are not sandwiched between the bosses <NUM> and the spring housing portions <NUM>, and application of excessive stress to the bosses <NUM> is suppressed.

Here, a length L1 in the circumferential directions S (see <FIG>) from the end 90AA of the pressure-side assist cam surface 90A in the first direction D1 of one pressure-side cam portion <NUM> located on the side of the first circumferential direction S1 in the pressure-side cam portions <NUM> adjacent to each other in the circumferential directions S to an end 90SA of the pressure-side slipper cam surface <NUM> in the first direction D1 of the other pressure-side cam portion <NUM> located on the side of the second circumferential direction S2 is larger than a length L2 in the circumferential directions (see <FIG>) from an end 60AA of the center-side assist cam surface 60A in the second direction D2 to the end 60SA of the center-side slipper cam surface <NUM> in the second direction D2 in one center-side cam portion <NUM>.

When seen in the axial directions of the output shaft <NUM>, an angle θ1 (see <FIG>) defined by a center 80C of the cylindrical portion <NUM>, the end 90AB of the pressure-side assist cam surface 90A in the first circumferential direction S1 located on the side of the first circumferential direction S1 of one pressure-side cam portion <NUM> in the pressure-side cam portions <NUM> adjacent to each other in the circumferential directions S, and the end 90SB of the pressure-side slipper cam surface <NUM> in the first circumferential direction S1 located on the side of the second circumferential direction S2 of the other pressure-side cam portion <NUM> is larger than an angle θ2 (see <FIG>) defined by a center 50C of the output shaft holding portion <NUM>, the end 60AB of the center-side assist cam surface 60A in the second circumferential direction S2, and the end 60SB of the center-side slipper cam surface <NUM> in the second circumferential direction S2 in one center-side cam portion <NUM>.

A length L3 in the circumferential directions S (see <FIG>) from the end 60AA of the center-side assist cam surface 60A in the second direction D2 to the boss <NUM> is larger than a length L4 in the circumferential directions S (see <FIG>) from the end 90AA of the pressure-side assist cam surface 90A in the first direction D1 to the insertion hole <NUM>.

When seen in the axial directions of the output shaft <NUM>, an angle θ3 (see <FIG>) defined by the center 50C of the output shaft holding portion <NUM>, the end 60AB in the second circumferential direction S2 of the center-side assist cam surface 60A of the center-side cam portion <NUM>, and a center 54C of the boss <NUM> is larger than an angle θ4 (see <FIG>) defined by the center 80C of the cylindrical portion <NUM>, the end 90AB of the pressure-side assist cam surface 90A in the first circumferential direction S1, and a center 84HC of the insertion hole <NUM>.

The clutch device <NUM> is filled with a predetermined amount of clutch oil. Clutch oil is distributed in the clutch center <NUM> and the pressure plate <NUM> through the hollow portion <NUM> of the output shaft <NUM>, and then is supplied to the input-side rotating plates <NUM> and the output-side rotating plates <NUM> through the gap between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM> and the oil flow holes <NUM>. Clutch oil reduces or prevents absorption of heat and abrasion of the friction members. The clutch device <NUM> according to this preferred embodiment is a so-called multiplate wet friction clutch device.

Operation of the clutch device <NUM> according to this preferred embodiment will now be described. As described above, the clutch device <NUM> is disposed between the engine and the transmission of the motorcycle, and allows or interrupts transfer of a rotation driving force of the engine to the transmission by driver's clutch operation (e.g., driver's operation of a clutch operation lever or an operation button).

In the clutch device <NUM>, in a case where the driver of the motorcycle does not perform clutch operation (e.g., a case where the driver does not operate a clutch operation lever), a clutch release mechanism (not shown) does not press the push rod 16A, and thus, the pressure plate <NUM> presses the input-side rotating plates <NUM> with a biasing force (elastic force) of the pressure springs <NUM>. Accordingly, the clutch center <NUM> enters a clutch-ON state (i.e., clutch engaged state) in which the input-side rotating plates <NUM> and the output-side rotating plates <NUM> are pushed against each other to be friction coupled, and is rotationally driven. That is, a rotation driving force of the engine is transferred to the clutch center <NUM>, and the output shaft <NUM> is rotationally driven.

In the clutch-ON state, clutch oil distributed in the hollow portion H of the output shaft <NUM> and having flowed out from the distal end 15T of the output shaft <NUM> is dropped or spattered in the cylindrical portion <NUM> and attached to the cylindrical portion <NUM> (see arrow F in <FIG>). The clutch oil attached to the inside of the cylindrical portion <NUM> is guided into the clutch center <NUM>. Accordingly, clutch oil flows out of the clutch center <NUM> through the oil flow holes <NUM>. Clutch oil also flows out of the clutch center <NUM> through the gap between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM>. Then, clutch oil that has flowed out of the clutch center <NUM> is supplied to the input-side rotating plates <NUM> and the output-side rotating plates <NUM>.

On the other hand, in the clutch device <NUM>, when the driver of the motorcycle performs clutch operation (e.g., the driver operates the clutch operation lever) in the clutch-ON state, the clutch release mechanism (not shown) presses the push rod 16A, and thus, the pressure plate <NUM> is displaced in a direction away from the clutch center <NUM> (second direction D2) against a biasing force of the pressure springs <NUM>. Accordingly, the clutch center <NUM> enters a clutch-OFF state (clutch disengaged stage) in which friction coupling between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> is canceled, and thus, rotational driving attenuates or stops. That is, a rotation driving force of the engine is interrupted to the clutch center <NUM>. The pressure plate <NUM> moves in the second direction D2 when the state where the clutch is engaged (clutch ON state) is switched to the state where the clutch is disengaged (clutch OFF state) through the half-clutch state by clutch operation of the driver.

In the clutch-OFF state, clutch oil distributed in the hollow portion H of the output shaft <NUM> and having flowed out of the distal end 15T of the output shaft <NUM> is guided into the clutch center <NUM> in the same or substantially the same manner as in the clutch-ON state. At this time, since the pressure plate <NUM> is separated from the clutch center <NUM>, the amount of fitting between the pressure plate <NUM> and each of the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM> decreases. As a result, clutch oil in the cylindrical portion <NUM> actively flows out of the clutch center <NUM>, and is distributed to portions in the clutch device <NUM>. In particular, clutch oil can be actively guided to gaps between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> separated from each other.

Then, when the driver cancels the clutch operation lever in the clutch-OFF state, pressing of the pressure plate <NUM> by the clutch release mechanism (not shown) through the push member 16B is canceled, and thus, the pressure plate <NUM> is displaced with a biasing force of the pressure springs <NUM> to a direction (first direction D1) of approaching the clutch center <NUM>.

<FIG> is a partially enlarged cross-sectional view of the normal state (clutch engaged state) of a clutch device <NUM> according to a second preferred embodiment and a clutch device <NUM> according to a third preferred embodiment. As illustrated in <FIG>, in the clutch device <NUM> and the clutch device <NUM>, in the clutch engaged state, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G1. In the clutch engaged state, the distance LX between the center-side fitting teeth <NUM> and the pressure-side fitting teeth <NUM> in the radial directions is smaller than a distance LZ between the ends 47T of the center-side fitting teeth <NUM> in the second direction D2 and the pressure plate <NUM> (flange <NUM> in this preferred embodiment). The distance LX may be larger than the distance LZ. In the clutch device <NUM> and the clutch device <NUM>, when the temperature changes in a usable temperature range (e.g., about -<NUM> to about <NUM>) from a low temperature range (e.g., about -<NUM> to about <NUM>) to a high temperature range (e.g., about <NUM> to about <NUM>), a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (see <FIG>) over the entire usable temperature range. The low temperature range is, for example, an outdoor temperature before the engine starts. The high temperature range is, for example, a temperature of the clutch device <NUM>, <NUM> in operation after warming up of the engine.

As illustrated in <FIG>, in the clutch device <NUM> according to the second preferred embodiment, when the pressure plate <NUM> moves in a direction away from the clutch center <NUM> (i.e., in the second direction D2), the whole of the input-side rotating plates <NUM> and the output-side rotating plates <NUM> remains in the clutch center <NUM>, and a gap (gap in the directions D) is formed between the pressure plate <NUM> (more specifically, the flange <NUM>) and an input-side rotating plate 20A located at the front in the second direction D2 in the plurality of input-side rotating plates <NUM> and the plurality of output-side rotating plates <NUM>.

As illustrated in <FIG>, in the clutch device <NUM>, in the half-clutch state, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G2 (G1 > G2). That is, no gap is formed in the directions D between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the ends 47T of the center-side fitting teeth <NUM> in the second direction D2. Accordingly, even in a case where clutch oil flowing from the inside of the clutch center <NUM> is spattered to the radially outside by the centrifugal force, a most portion of the clutch oil hits the pressure-side fitting teeth <NUM>, and as a result, clutch oil is supplied to, for example, the output-side rotating plates <NUM> held by the pressure-side fitting teeth <NUM>. The half-clutch state refers to a state between the state where the clutch is engaged (see <FIG>) and the state where the clutch is disengaged (see <FIG>).

As illustrated in <FIG>, in the clutch device <NUM>, in the clutch disengaged state, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G3 (G2 > G3). That is, no gap is formed in the directions D between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the ends 47T of the center-side fitting teeth <NUM> in the second direction D2.

As illustrated in <FIG>, in the clutch device <NUM>, in a state where the pressure plate <NUM> is in contact with the stopper plate <NUM>, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G4 (G3 > G4). That is, no gap is formed in the directions D between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the ends 47T of the center-side fitting teeth <NUM> in the second direction D2.

As illustrated in <FIG>, in the clutch device <NUM> according to the third preferred embodiment, when the pressure plate <NUM> moves in a direction away from the clutch center <NUM> (i.e., in the second direction D2), only an input-side rotating plate 20B located at the front in the first direction D1 in the input-side rotating plates <NUM> remains in the clutch center <NUM>, and a gap (gap in the directions D) is formed between the input-side rotating plate 20B and the output-side rotating plates <NUM>. The gap in the directions D formed when the pressure plate <NUM> moves away from the clutch center <NUM> is not limited to a gap between the input-side rotating plate 20B and the output-side rotating plates <NUM>. For example, the gap may be formed between the clutch center <NUM> and the input-side rotating plate 20B, between adjacent ones of the input-side rotating plates <NUM> and output-side rotating plates <NUM>, or between the pressure plate <NUM> and the input-side rotating plates <NUM>.

As illustrated in <FIG>, in the clutch device <NUM>, in the half-clutch state, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G5 (G1 > G5). That is, no gap is formed in the directions D between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the ends 47T of the center-side fitting teeth <NUM> in the second direction D2.

As illustrated in <FIG>, in the clutch device <NUM>, in the clutch disengaged state, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G6 (G5 > G6). That is, no gap is formed in the directions D between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the ends 47T of the center-side fitting teeth <NUM> in the second direction D2.

As illustrated in <FIG>, in the clutch device <NUM>, in a state where the pressure plate <NUM> is in contact with the stopper plate <NUM>, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM> (i.e., when seen in a direction orthogonal to the directions D). In this preferred embodiment, in the directions D, the center-side fitting teeth <NUM> overlap with the pressure-side fitting teeth <NUM> in a length G7 (G6 > G7). That is, no gap is formed in the directions D between the ends 77T of the pressure-side fitting teeth <NUM> in the first direction D1 and the ends 47T of the center-side fitting teeth <NUM> in the second direction D2.

As described above, in the clutch device <NUM> according to the second preferred embodiment and the clutch device <NUM> according to the third preferred embodiment, in each of the half-clutch state, the clutch disengaged state, and the state where the pressure plate <NUM> is in contact with the stopper plate <NUM>, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM>. That is, in each of the half-clutch state, the clutch disengaged state, and the state where the pressure plate <NUM> is in contact with the stopper plate <NUM>, since no gap is formed between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM> in the directions D, clutch oil flowing in the clutch center <NUM> does not flow directly to the outside and flows to the pressure plate <NUM>, for example. Accordingly, a larger amount of clutch oil can be supplied to the output-side rotating plates <NUM> and the input-side rotating plates <NUM> held by the pressure plate <NUM>.

In the clutch device <NUM> according to the second preferred embodiment and the clutch device <NUM> according to the third preferred embodiment, when seen in the radial directions of the output shaft <NUM>, the pair of side surfaces 77F of each of the pressure-side fitting teeth <NUM> in the circumferential directions S tilt to approach each other in the first direction D1. In this configuration, the pressure plate <NUM> can be easily moved toward or away from the clutch center <NUM>.

In the clutch device <NUM> according to the second preferred embodiment and the clutch device <NUM> according to the third preferred embodiment, in the clutch engaged state, the distance LX between the center-side fitting teeth <NUM> and the pressure-side fitting teeth <NUM> in the radial directions S may be larger than the distance LZ between the ends 47T of the center-side fitting teeth <NUM> in the second direction D2 and the pressure plate <NUM> in the directions D. In this configuration, clutch oil more easily flows in the gap between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM>.

In the clutch device <NUM> according to the second preferred embodiment and the clutch device <NUM> according to the third preferred embodiment, when the temperature of each of the clutch device <NUM> and the clutch device <NUM> changes in a usable temperature range from a low temperature range to a high temperature range, a portion of one of the center-side fitting teeth <NUM> overlap with a portion of one of the pressure-side fitting teeth <NUM> when seen in the radial directions of the output shaft <NUM>, over the entire usable temperature range. With this configuration, in the usable temperature range of the clutch device <NUM> and the clutch device <NUM>, no gap is formed between the pressure-side fitting teeth <NUM> and the center-side fitting teeth <NUM> in the directions D, and thus, clutch oil flowing in the clutch center <NUM> does not flow directly to the outside but flows to the pressure plate <NUM>, for example. Accordingly, a larger amount of clutch oil can be supplied to the output-side rotating plates <NUM> and the input-side rotating plates <NUM> held by the pressure plate <NUM>.

<FIG> is a disassembled perspective view of a clutch center <NUM> and a pressure plate <NUM> of a clutch device <NUM> according to a fourth preferred embodiment.

The clutch center <NUM> is housed in a clutch housing <NUM> (see <FIG>). The clutch center <NUM> and the clutch housing <NUM> are concentrically disposed. As illustrated in <FIG>, the clutch center <NUM> includes a body <NUM>, and a flange <NUM> connected to the outer edge of the body <NUM> on the side of the first direction D1 and extending radially outward. The body <NUM> projects ahead of the flange <NUM> in the second direction D2. The clutch center <NUM> does not hold the output-side rotating plates <NUM>. The clutch center <NUM> is rotationally driven together with an output shaft <NUM> (see <FIG>).

As illustrated in <FIG>, the body <NUM> includes an output shaft holding portion <NUM>, a plurality of center-side cam portions <NUM>, and a center-side fitting portion <NUM>. The center-side cam portions <NUM> projects from the flange <NUM> in the second direction D2. The center-side cam portions <NUM> are located radially outward of the output shaft holding portion <NUM>. The center-side cam portions <NUM> are formed integrally with the output shaft holding portion <NUM>.

The output shaft holding portion <NUM> has a cylindrical shape. The output shaft holding portion <NUM> has an insertion hole <NUM> in which the output shaft <NUM> (see <FIG>) is inserted and spline-fitted. The insertion hole <NUM> penetrates the body <NUM>. An inner peripheral surface 350A of the output shaft holding portion <NUM> defining the insertion hole <NUM> includes a plurality of spline grooves formed along the axial direction. The output shaft <NUM> is coupled to the output shaft holding portion <NUM>.

As illustrated in <FIG>, the clutch center <NUM> includes a plurality of (for example, three in this preferred embodiment) bosses <NUM>. The bosses <NUM> are located radially outward of the output shaft holding portion <NUM>. The bosses <NUM> are disposed on the body <NUM>.

As illustrated in <FIG>, the clutch center <NUM> includes center-side cam holes <NUM> penetrating the body <NUM> and a portion of the flange <NUM>. The center-side cam holes <NUM> penetrate the body <NUM> and the flange <NUM> in the directions D. The center-side cam holes <NUM> extend from portions on the side of the output shaft holding portion <NUM> to the flange <NUM>. The center-side cam holes <NUM> are formed between the center-side assist cam surface 60A of the center-side cam portions <NUM> and the bosses <NUM>. When seen in the axial direction of the clutch center <NUM>, the center-side assist cam surface 60A overlaps with a portion of the center-side cam holes <NUM>.

As illustrated in <FIG>, the center-side fitting portion <NUM> is disposed on the body <NUM>. The center-side fitting portion <NUM> is located radially outward of the center-side cam portions <NUM>. The center-side fitting portion <NUM> is located ahead of the center-side cam portions <NUM> in the first direction D1. The center-side fitting portion <NUM> is configured to slidably fit in the pressure-side fitting portion <NUM> (see <FIG>).

As illustrated in <FIG>, the flange <NUM> extends radially outward from the outer edge of the body <NUM>. In this preferred embodiment, the flange <NUM> extends radially outward form the outer edge of the center-side fitting portion <NUM>. The flange <NUM> is configured to press the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. The flange <NUM> is located ahead of the input-side rotating plates <NUM> and the output-side rotating plates <NUM> in the first direction D1. The input-side rotating plates <NUM> and the output-side rotating plates <NUM> are sandwiched between the flange <NUM> and the flange <NUM> of the pressure plate <NUM>.

The pressure plate <NUM> is movable toward or away from the clutch center <NUM> and rotatable relative to the clutch center <NUM>. The pressure plate <NUM> is configured to press the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. The pressure plate <NUM> is disposed coaxially with the clutch center <NUM> and the clutch housing <NUM>. The pressure plate <NUM> includes a cylindrical body <NUM>, and the flange <NUM> extending radially outward from the outer edge of the body <NUM>. The pressure plate <NUM> includes the plurality of output-side rotating plates <NUM> arranged alternately with the input-side rotating plates <NUM> in the directions D. In this preferred embodiment, the output-side rotating plates <NUM> are held only by the pressure plate <NUM>.

As illustrated in <FIG>, the body <NUM> includes a ring-shaped base wall <NUM>, an outer peripheral wall <NUM> located radially outward of the base wall <NUM> and extending in the first direction D1, a cylindrical portion <NUM> disposed at a center of the base wall <NUM>, a plurality of pressure-side cam portions <NUM> connected to the base wall <NUM> and the outer peripheral wall <NUM>, a pressure-side fitting portion <NUM>, and spring housing portions <NUM> (see <FIG>). The pressure-side cam portions <NUM> project from the body <NUM> in the first direction D1. The pressure-side cam portions <NUM> are located radially outward of the cylindrical portion <NUM>. The pressure-side cam portions <NUM> are located inward of the outer peripheral wall <NUM>.

The cylindrical portion <NUM> has a cylindrical shape. The cylindrical portion <NUM> is formed integrally with the pressure-side cam portions <NUM>. The cylindrical portion <NUM> houses a distal end 15T of the output shaft <NUM> (see <FIG>). The cylindrical portion <NUM> houses a release bearing <NUM> (see <FIG>). The cylindrical portion <NUM> receives a pressing force from a push member 16B. The cylindrical portion <NUM> receives clutch oil that has flowed out from the distal end 15T of the output shaft <NUM>.

As illustrated in <FIG>, an outer peripheral wall <NUM> of the pressure plate <NUM> is located radially outward of the cylindrical portion <NUM>. The outer peripheral wall <NUM> is integrally formed with the cylindrical portion <NUM>. The outer peripheral wall <NUM> has a ring shape extending in the directions D. An outer peripheral surface 375A of the outer peripheral wall <NUM> has a spline fitting portion <NUM>. The spline fitting portion <NUM> includes a plurality of pressure-side fitting teeth <NUM> extending in the axial direction of the pressure plate <NUM> along the outer peripheral surface 375A of the outer peripheral wall <NUM>, a plurality of spline grooves <NUM> each formed between adjacent ones of the pressure-side fitting teeth <NUM> and extending in the axial direction of the pressure plate <NUM>, and oil flow holes <NUM>. The pressure-side fitting teeth <NUM> hold the output-side rotating plates <NUM>. The plurality of pressure-side fitting teeth <NUM> are arranged in the circumferential directions S. The plurality of pressure-side fitting teeth <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S. The plurality of pressure-side fitting teeth <NUM> have the same or substantially the same shape. The pressure-side fitting teeth <NUM> project radially outward form the outer peripheral surface 375A of the outer peripheral wall <NUM>. A pair of side surfaces 377F of each of the pressure-side fitting teeth <NUM> in the circumferential directions S tilt to gradually approach each other in the first direction D1 when seen in the radial directions of the output shaft <NUM>. The oil flow holes <NUM> penetrate the outer peripheral wall <NUM> in the radial directions. Each of the oil flow holes <NUM> is formed between adjacent ones of the pressure-side fitting teeth <NUM>. That is, the oil flow holes <NUM> are formed in the spline grooves <NUM>. The oil flow holes <NUM> are formed at the sides of the pressure-side cam portions <NUM>. More specifically, the oil flow holes <NUM> are formed at the sides of pressure-side assist cam surfaces 90A of the pressure-side cam portions <NUM>. The oil flow holes <NUM> are located ahead of the pressure-side assist cam surfaces 90A in the first circumferential direction S1. The oil flow holes <NUM> are located ahead of pressure-side slipper cam surfaces <NUM> in the second circumferential direction S2. In this preferred embodiment, three oil flow holes <NUM> are formed in each of three portions of the outer peripheral wall <NUM> in the circumferential directions S. The oil flow holes <NUM> are arranged at regular or substantially regular intervals in the circumferential directions S. The oil flow holes <NUM> cause the inside and outside of the pressure plate <NUM> to communicate with each other. The oil flow holes <NUM> allow clutch oil that has flowed from the output shaft <NUM> into the pressure plate <NUM> to be discharged to the outside of the pressure plate <NUM>. In this Preferred embodiment, the oil flow holes <NUM> allow clutch oil flowing at an inner peripheral surface 375B of the outer peripheral wall <NUM> to be discharged to the outside of the pressure plate <NUM>. At least a portion of the oil flow holes <NUM> faces the center-side fitting portion <NUM> (see <FIG>).

The output-side rotating plates <NUM> are held by the spline fitting portion <NUM> of the pressure plate <NUM>. The output-side rotating plates <NUM> are held by the pressure-side fitting teeth <NUM> and the spline grooves <NUM> by spline-fitting. The output-side rotating plates <NUM> are displaceable along the axial direction of the pressure plate <NUM>. The output-side rotating plates <NUM> are rotatable together with the pressure plate <NUM>.

As illustrated in <FIG> and <FIG>, the pressure plate <NUM> includes pressure-side cam holes <NUM> penetrating a portion of the base wall <NUM>. The pressure-side cam holes <NUM> penetrate the base wall <NUM> in the directions D. The pressure-side cam holes <NUM> are located radially outward of the cylindrical portion <NUM>. The pressure-side cam holes <NUM> extend from the sides of the cylindrical portion <NUM> to the outer peripheral wall <NUM>. Each of the pressure-side cam holes <NUM> penetrates a portion between adjacent ones of the pressure-side cam portions <NUM>. Each of the pressure-side cam holes <NUM> penetrates a portion between the pressure-side assist cam surface 90A and the pressure-side slipper cam surface <NUM> of adjacent ones of the pressure-side cam portions <NUM>. When seen in the axial direction of the pressure plate <NUM>, the pressure-side assist cam surface 90A overlaps with a portion of the pressure-side cam holes <NUM>. Clutch oil flows into the pressure-side cam holes <NUM> from the outside of the pressure plate <NUM>.

As illustrated in <FIG>, the pressure-side fitting portion <NUM> is located radially outward of the cylindrical portion <NUM>. The pressure-side fitting portion <NUM> is located radially outward of the pressure-side cam portions <NUM>. The pressure-side fitting portion <NUM> is located ahead of the pressure-side cam portions <NUM> in the first direction D1. The pressure-side fitting portion <NUM> is formed on the inner peripheral surface 375B of the outer peripheral wall <NUM>. The pressure-side fitting portion <NUM> is configured to slidably fit on the center-side fitting portion <NUM> (see <FIG>). A gap is formed between the pressure-side fitting portion <NUM> and the center-side fitting portion <NUM>.

The foregoing description is directed to the preferred embodiments of the present disclosure. The preferred embodiments described above, however, are merely an example, and the present disclosure can be performed in various modes and through various preferred embodiments.

In the preferred embodiments described above, the clutch devices <NUM>, <NUM>, <NUM>, and <NUM> are so-called manual clutches each configured to allow or interrupt transfer of a rotation driving force of an engine to a transmission by clutch operation of a driver (e.g., operation of a clutch operation lever by a driver), but are not limited to such clutches. The clutch devices <NUM>, <NUM>, <NUM>, and <NUM> may also be so-called automated clutches each configured to allow or interrupt transfer of a rotation driving force of an engine to a transmission automatically by a clutch actuator.

In each of the preferred embodiments described above, the output shaft holding portion <NUM> and the outer peripheral wall <NUM> are integrally formed in the clutch center <NUM>, but the present disclosure is not limited to this example. For example, the clutch center <NUM> may include a first member including the output shaft holding portion <NUM> and a second member formed as a separate component from the first member and including the outer peripheral wall <NUM> so that the first member and the second member are fitted to each other in application.

In the fourth preferred embodiment, the clutch center <NUM> does not hold the output-side rotating plates <NUM>, but the present disclosure is not limited to this example. The clutch center <NUM> may include center-side fitting teeth having a configuration similar to the pressure-side fitting teeth <NUM> of the first preferred embodiment capable of holding the output-side rotating plates <NUM>.

Claim 1:
A clutch device (<NUM>, <NUM>, <NUM>) to allow or interrupt transfer of a rotation driving force of an input shaft to an output shaft (<NUM>), the clutch device (<NUM>, <NUM>, <NUM>) comprising:
a clutch center (<NUM>) housed in a clutch housing (<NUM>) holding a plurality of input-side rotating plates (<NUM>) to be rotationally driven by rotational driving of the input shaft, the clutch center (<NUM>) being operable to hold a plurality of output-side rotating plates (<NUM>) and to be rotationally driven together with the output shaft (<NUM>), the input-side rotating plates (<NUM>) and the output-side rotating plates (<NUM>) being alternately arranged;
a pressure plate (<NUM>) movable toward or away from the clutch center (<NUM>) and rotatable relative to the clutch center (<NUM>) to press the input-side rotating plates (<NUM>) and the output-side rotating plates (<NUM>); and
a stopper plate (<NUM>) operable to contact the pressure plate (<NUM>) and to suppress separation of the pressure plate (<NUM>) from the clutch center (<NUM>) by a predetermined distance or more, wherein:
the clutch center (<NUM>) includes a boss (<NUM>) extending toward the pressure plate (<NUM>);
the stopper plate (<NUM>) is fixed to the boss (<NUM>);
the pressure plate (<NUM>) includes:
a plurality of pressure-side fitting teeth (<NUM>) holding at least one of the output-side rotating plates (<NUM>) and arranged in circumferential directions (S);
the clutch center (<NUM>) includes:
an output shaft holding portion (<NUM>) to which the output shaft (<NUM>) is coupled;
an outer peripheral wall (<NUM>) located radially outward of the output shaft holding portion (<NUM>); and
a plurality of center-side fitting teeth (<NUM>) holding the output-side rotating plates (<NUM>), projecting radially outward from an outer peripheral surface of the outer peripheral wall (<NUM>), and arranged in circumferential directions (S);
characterized in that,
in a state where the pressure plate (<NUM>) is in contact with the stopper plate (<NUM>), a portion of one of the center-side fitting teeth (<NUM>) overlap with a portion of one of the pressure-side fitting teeth (<NUM>) when seen in radial directions of the output shaft (<NUM>).