Patent Description:
<CIT>, <CIT> and <CIT> disclose a clutch device according to the preamble of claim <NUM>. 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>, 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 employs an assembly of the clutch center and the pressure plate.

In the clutch device of <CIT>, for example, 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 directions.

Clutch oil that has flowed from the output shaft is distributed in the clutch center. A portion of the clutch oil flows to the outside of the clutch center through a gap between the clutch center and the pressure plate. In the outside of the clutch center, the input-side rotating plates and the output-side rotating plates held by the center-side fitting teeth are disposed. Thus, it is desired that clutch oil efficiently flows from the inside of the clutch center to be supplied to the input-side rotating plates and the output-side rotating plates.

It is an object of the present invention to provide clutch devices each capable of causing clutch oil to flow efficiently from an inside to an outside of a clutch center to supply clutch oil to input-side rotating plates and output-side rotating plates, and motorcycles including such clutch devices. According to the present invention said object is solved by a clutch device having the features of the independent claim <NUM>. Preferred embodiments are laid down in the dependent claims.

A clutch device according to a preferred embodiment of the present invention is a clutch device to allow or interrupt transfer of a rotation driving force of an input shaft, and includes 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 holding a plurality of output-side rotating plates and being operable to be rotationally driven together with the output shaft, the input-side rotating plates and the output-side rotating plates being alternately arranged, and a pressure plate movable toward or away from the clutch center and rotatable relative to the clutch center, the pressure plate being operable to press the input-side rotating plates and the output-side rotating plates, wherein 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, 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 an oil channel located in an end portion of at least one of the center-side fitting teeth in a second direction, a direction in which the pressure plate moves toward the clutch center being a first direction, a direction in which the pressure plate moves away from the clutch center being the second direction, and the oil channel allows clutch oil flowing at least at an inner peripheral surface of the outer peripheral wall to be discharged to outside of the clutch center.

In a clutch device according to a preferred embodiment of the present invention, the oil channel of the clutch center is located in an end portion of at least one of the center-side fitting teeth in the second direction, and clutch oil flowing at least at the inner peripheral surface of the outer peripheral wall is discharged to the outside of the clutch center. Accordingly, a larger amount of clutch oil flowing between the clutch center and the pressure plate flows to the outside of the clutch center through the oil channels. That is, since a larger amount of clutch oil flows from the inside of the clutch center, clutch oil can be efficiently supplied to the input-side rotating plates and the output-side rotating plates located outward of the center-side fitting teeth.

In another 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 includes 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 holding a plurality of output-side rotating plates and being operable to be rotationally driven together with the output shaft, the input-side rotating plates and the output-side rotating plates being alternately arranged, and a pressure plate movable toward or away from the clutch center and rotatable relative to the clutch center, the pressure plate being operable to press the input-side rotating plates and the output-side rotating plates, wherein 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, 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 a recess that is recessed in a first direction from an end surface of at least one of the center-side fitting teeth in a second direction, a direction in which the pressure plate moves toward the clutch center being a first direction, a direction in which the pressure plate moves away from the clutch center being the second direction, and the recess is open toward an inner peripheral surface and an outer peripheral surface of the outer peripheral wall.

In this clutch device according to a preferred embodiment of the present invention, the clutch center includes the recess that is recessed in the first direction from an end surface of at least one of the center-side fitting teeth in the second direction, and the recess is open toward the inner peripheral surface and the outer peripheral surface of the outer peripheral wall. Accordingly, while the clutch center rotates, for example, clutch oil flowing at the inner peripheral surface of the outer peripheral wall can flow toward the outer peripheral surface through the recess, and clutch oil can be efficiently supplied to the input-side rotating plates and the output-side rotating plates located outward of the center-side fitting teeth, for example.

Preferred embodiments of the present invention provide clutch devices each capable of causing clutch oil to flow efficiently from the inside to outside of a clutch center to supply clutch oil to input-side rotating plates and output-side rotating plates.

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> and the clutch center <NUM> are arranged will be referred to as directions D, 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> moves 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 invention.

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> defines and functions 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, for example, is located 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 arranged 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>. An outer peripheral surface 45A 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 45A of the outer peripheral wall <NUM>, a plurality of spline grooves <NUM> each located 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 45A of the outer peripheral wall <NUM>. The number of the center-side fitting teeth <NUM> is preferably a multiple of the number of the center-side cam portions <NUM>. In this preferred embodiment, for example, the number of the center-side cam portions <NUM> is three, and the number of the center-side fitting teeth <NUM> is <NUM>, which will be described later. The number of the center-side fitting teeth <NUM> may not be a multiple of the number of the center-side cam portions <NUM>. The oil flow holes <NUM> penetrate the outer peripheral wall <NUM> along the radial directions. Each of the oil flow holes <NUM> is located between adjacent ones of the center-side fitting teeth <NUM>. That is, the oil flow holes <NUM> are located in the spline grooves <NUM>. The oil flow holes <NUM> are located at the sides of the center-side cam portions <NUM>. More specifically, the discharge holes <NUM> are located 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. In this preferred embodiment, three oil flow holes <NUM> are provided 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 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>. In this preferred embodiment, the oil flow holes <NUM> allow clutch oil flowing at an inner peripheral surface 45B of the outer peripheral wall <NUM> to be discharged to the outside of the clutch center <NUM>. At least a portion of the oil flow holes <NUM> is located at a position facing a pressure-side fitting portion <NUM> described later.

As illustrated in <FIG>, the clutch center <NUM> includes a plurality of oil channels <NUM> located in the center-side fitting teeth <NUM>. As illustrated in <FIG>, the oil channels <NUM> are located in end portions 47E of the center-side fitting teeth <NUM> in the second direction D2. The oil channels <NUM> are open toward the outer peripheral surface 45A and the inner peripheral surface 45B of the outer peripheral wall <NUM>. The oil channels <NUM> cause the outer peripheral surface 45A and the inner peripheral surface 45B of the outer peripheral wall <NUM> to communicate with each other. The oil channels <NUM> cause clutch oil flowing at least at the inner peripheral surface 45B of the outer peripheral wall <NUM> to be discharged to the outside of the clutch center <NUM>. In this preferred embodiment, the oil channels <NUM> are recessed grooves that are recessed in the first direction D1 from end surfaces 47T of the center-side fitting teeth <NUM> in the second direction D2 (see also <FIG>). The oil channels <NUM> are an example of a recess. As illustrated in <FIG>, each of the oil channels <NUM> has a substantially circular shape (see also <FIG>). The shape of each oil channel <NUM> is not particularly limited. A portion of the oil channels <NUM> is located radially outward of the center-side cam portions <NUM> described later. A portion of the oil channels <NUM> is located radially outward of center-side cam holes <NUM> described later. A portion of the oil channels <NUM> is located radially outward of through holes 43P. The oil channels <NUM> are located at positions facing the pressure-side fitting portion <NUM> (see <FIG>) described later of the pressure plate <NUM>. As illustrated in <FIG>, a center-side fitting tooth 47C including no oil channels <NUM> is disposed between one center-side fitting tooth 47A including the oil channel <NUM> and another center-side fitting tooth 47B including the oil channel <NUM>. In this preferred embodiment, the oil channel <NUM> is provided in every other one of the center-side fitting teeth <NUM> arranged in the circumferential directions S, but the oil channel <NUM> may be provided in every two of the center-side fitting teeth <NUM> or in every three or more of the center-side fitting teeth <NUM>. The oil channel <NUM> may be provided in each of adjacent ones of the center-side fitting teeth <NUM>. The oil channels <NUM> are formed by pushing a core pin against the end surfaces 47T of the center-side fitting teeth <NUM> in the second direction D2 when the pressure plate <NUM> formed with a mold is detached from the mold, or are formed by cutting, for example. The oil channels <NUM> also define and function as channels that guide clutch oil flowing at the outer peripheral surface 45A of the outer peripheral wall <NUM> (i.e., clutch oil adhering to surfaces <NUM> of the center-side fitting teeth <NUM>) to the inside of the clutch center <NUM>. For example, when rotation of the clutch center <NUM> stops (e.g., when the engine stops), in the oil channels <NUM> located above the clutch center <NUM>, clutch oil adhering to the surfaces <NUM> of the center-side fitting teeth <NUM> flows at the inner peripheral surface 45B of the clutch center <NUM> through the oil channels <NUM> by gravity. When rotation of the clutch center <NUM> stops, in the oil channels <NUM> located below the clutch center <NUM>, clutch oil adhering to the inner peripheral surface 45B of the outer peripheral wall <NUM> of the center-side fitting teeth <NUM> flows at the surfaces <NUM> of the center-side fitting teeth <NUM> through the oil channels <NUM> by gravity. That is, while the clutch center <NUM> does not rotate, clutch oil can flow from the inside to outside of the clutch center <NUM> through the oil channels <NUM> and also flow from the outside to the inside of the clutch center <NUM> at the same time.

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> preferably 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 to increase 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 from the pressure plate <NUM> toward 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> and <FIG>, the clutch center <NUM> includes center-side cam holes <NUM> penetrating a portion of the base wall <NUM>. The center-side cam holes <NUM> penetrate the base wall <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 outer peripheral wall <NUM>. Each of the center-side cam holes <NUM> is located 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> and <FIG>, the clutch center <NUM> includes through holes 43P penetrating a portion of the base wall <NUM>. The through holes 43P penetrate the base wall <NUM> in the directions D. Each of the through hole 43P is located between the center-side slipper cam surface <NUM> of the center-side cam portion <NUM> and the center-side cam hole <NUM>. The through holes 43P are located between the center-side slipper cam surface <NUM> of the center-side cam portions <NUM> and the bosses <NUM>. The through hole 43P is located ahead of the center-side slipper cam surface <NUM> in the first circumferential direction S1. The through hole 43P is located ahead of the boss <NUM> in the second circumferential direction S2. The oil flow holes <NUM> are located radially outward of the through holes 43P. The through holes 43P are smaller than the center-side cam holes <NUM>. The through holes 43P causes the inside and outside of the clutch center <NUM> to communicate with each other. The through holes 43P are configured to guide clutch oil flowing outside the clutch center <NUM> to the inside of the clutch center <NUM>. More specifically, as indicated by arrow FS in <FIG>, clutch oil that has flowed out from the output shaft <NUM> toward the clutch center <NUM> flows into the clutch center <NUM> through the through holes 43P.

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 located 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 located 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>, 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 pressure plate <NUM> holds the plurality of output-side rotating plates <NUM> arranged alternately with the input-side rotating plates <NUM>. The output-side rotating plates <NUM> are displaceable along the axial directions of the pressure plate <NUM>. The output-side rotating plates <NUM> are rotatable together with pressure plate <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> preferably has 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 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 from the pressure plate <NUM> toward 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.

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 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, a contact pressure force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> increases.

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> and <FIG>, the pressure plate <NUM> has 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 located between adjacent ones of the pressure-side cam portions <NUM>. Each of the pressure-side cam holes <NUM> is located 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> and <FIG>, the spring housing portions <NUM> are located in the pressure-side cam portions <NUM>. The spring housing portions <NUM> are recessed from the second direction D2 in 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 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 radially winding spring stee.

As illustrated in <FIG>, the pressure-side fitting portion <NUM> is provided in the body <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>, the pressure plate <NUM> includes the plurality of pressure-side fitting teeth <NUM> disposed on the flange <NUM>. The pressure-side fitting teeth <NUM> hold the output-side rotating plates <NUM>. 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 pressure-side fitting teeth <NUM> are provided on the fitting tooth surface 98B of the flange <NUM>. The pressure-side fitting teeth <NUM> project in the first direction D1 from the fitting tooth surface 98B. The pressure-side fitting teeth <NUM> are arranged in the circumferential directions S. 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.

<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>. In the state illustrated in <FIG> (in the state of assembly), a distance L1 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 L2 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 reduced or prevented.

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 flowing at the inner peripheral surface 45B of the outer peripheral wall <NUM> of the clutch center <NUM> is discharged to the outside of the clutch center 45B through the oil channels <NUM>, as indicated by arrow FM in <FIG>. Clutch oil also flows from the outside of the clutch center <NUM> through the hollow portion <NUM> of the output shaft <NUM> and is distributed in the clutch center <NUM> through the center-side cam holes <NUM> and the through holes 43P. 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 operation of a clutch operation lever.

In the clutch device <NUM>, in a case where the driver of the motorcycle does not operate the 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 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 <NUM> 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 oil channels <NUM> and 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 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 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>.

In the clutch-OFF state, clutch oil distributed in the hollow portion <NUM> 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>.

As described above, in the clutch device <NUM> according to this preferred embodiment, the oil channels <NUM> of the clutch center <NUM> are located in the end portions 47E of the center-side fitting teeth <NUM> in the second direction D2, and allow clutch oil flowing at least at the inner peripheral surface 45B of the outer peripheral wall <NUM> to be discharged to the outside of the clutch center <NUM>. Accordingly, a larger amount of clutch oil flowing between the clutch center <NUM> and the pressure plate <NUM> flows to the outside of the clutch center <NUM> through the oil channels <NUM>. That is, since a larger amount of clutch oil flows from the inside of the clutch center <NUM>, clutch oil can be efficiently supplied to the input-side rotating plates <NUM> and the output-side rotating plates <NUM> located outward of the center-side fitting teeth <NUM>.

In the clutch device <NUM> according to this preferred embodiment, the oil channels <NUM> are recessed grooves that are recessed in the first direction D1 from the end surfaces 47T of the center-side fitting teeth <NUM> in the second direction D2. In this configuration, a larger amount of clutch oil in the clutch center <NUM> is allowed to flow to the outside with a relatively simple structure.

In the clutch device <NUM> according to this preferred embodiment, the clutch center <NUM> includes the plurality of center-side cam portions <NUM> located radially outward of the output shaft holding portion <NUM> and each including at least one of the center-side assist cam surface 60A operable to generate a force in a direction from the pressure plate <NUM> toward the clutch center <NUM> in order to increase a pressing force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> upon rotation relative to the pressure plate <NUM> and the center-side slipper cam surface <NUM> operable to cause the pressure plate <NUM> to move away from the clutch center <NUM> in order to reduce the pressing force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM> upon rotation relative to the pressure plate <NUM>, and the oil channels <NUM> are located radially outward of the center-side cam portions <NUM>. Clutch oil tends to be accumulated around the center-side cam portions <NUM> while the clutch center <NUM> rotates, and thus, the oil channels <NUM> arranged radially outward of the center-side cam portions <NUM> can cause the accumulated clutch oil to effectively flow to the outside from the oil channels <NUM>. Accordingly, a larger amount of clutch oil is caused to flow to the outside of the clutch center <NUM>.

In the clutch device <NUM> according to this preferred embodiment, the oil channels <NUM> are arranged radially outward of the through holes 43P. Since clutch oil flows into the through holes 43P from the outside of the clutch center <NUM>, the oil channels <NUM> arranged radially outward of the through holes 43P cause the clutch oil to effectively flow to the outside (i.e., toward the input-side rotating plates <NUM> and the output-side rotating plates <NUM>) from the oil channels <NUM>. Accordingly, a larger amount of clutch oil is caused to flow to the input-side rotating plates <NUM> and the output-side rotating plates <NUM>.

In the clutch device <NUM> according to this preferred embodiment, the clutch center <NUM> includes the center-side fitting portion <NUM> disposed in the inner peripheral surface 45B of the outer peripheral wall <NUM>, the pressure plate <NUM> includes the pressure-side fitting portion <NUM> slidably fitted in the center-side fitting portion <NUM>, and the oil channels <NUM> are arranged at positions facing the pressure-side fitting portion <NUM>. In this configuration, a larger amount of clutch oil in the clutch center <NUM> can be caused to flow to a portion between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM> through the oil channels <NUM>. Accordingly, a larger amount of clutch oil can be caused to flow to the outside of the clutch center <NUM> with sliding resistance between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM> reduced.

In the clutch device <NUM> according to this preferred embodiment, the center-side fitting tooth 47C including no oil channels <NUM> is disposed between one center-side fitting tooth 47A including the oil channel <NUM> and another center-side fitting tooth 47B including the oil channel <NUM>. With this configuration, clutch oil can be caused to flow to the outside of the clutch center <NUM> in a balanced manner.

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

In the preferred embodiments described above, each of the center-side cam portions <NUM> includes the center-side assist cam surface 60A and the center-side slipper cam surface <NUM>, but it is possible to only include at least one of the center-side assist cam surface 60A or the center-side slipper cam surface <NUM>.

Claim 1:
A clutch device (<NUM>) to allow or interrupt transfer of a rotation driving force of an input shaft to an output shaft (<NUM>), the clutch device (<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>) holding a plurality of output-side rotating plates (<NUM>) and being operable 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; and
a pressure plate (<NUM>) movable toward or away from the clutch center (<NUM>) and rotatable relative to the clutch center (<NUM>), the pressure plate (<NUM>) being operable to press the input-side rotating plates (<NUM>) and the output-side rotating plates (<NUM>); wherein
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>);
a plurality of center-side fitting teeth (<NUM>) holding the output-side rotating plates (<NUM>), projecting radially outward from an outer peripheral surface (45A) of the outer peripheral wall (<NUM>), and arranged in circumferential directions; characterized in that the clutch center (<NUM>) further includes
an oil channel (<NUM>) located in an end portion (47E) of at least one of the center-side fitting teeth (<NUM>) in a second direction (D2), a direction in which the pressure plate (<NUM>) moves toward the clutch center (<NUM>) being a first direction (D1), a direction in which the pressure plate (<NUM>) moves away from the clutch center (<NUM>) being the second direction (D2); wherein
the oil channel (<NUM>) allows clutch oil flowing at least at an inner peripheral surface (45B) of the outer peripheral wall (<NUM>) to be discharged to outside of the clutch center (<NUM>).