Patent Description:
Conventional vehicles such as motorcycles or the like include clutch devices. A clutch device is located between an engine and a drive wheel, and allows or blocks 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 rotatable by a rotation driving force of the engine and a plurality of output-side rotating plates connected with an output shaft that transfers the rotation driving force to the 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 or are separated from each other so that transfer of a rotation driving force is allowed or blocked.

<CIT>, for example, discloses a clutch device including a clutch center (clutch member) holding output-side rotating plates (driven clutch plates) and a pressure plate (pressure member) movable toward or away from the clutch center. The pressure plate is configured to be capable of pressing 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>, the clutch center includes center-side fitting teeth (an outer circumferential wall having a spline formed therein) as a member holding the output-side rotating plates, and the pressure plate includes pressure-side fitting teeth also as a member holding the output-side rotating plates. The clutch device is configured such that in a state where the clutch center and the pressure plate are assembled together, the center-side fitting teeth and the pressure-side fitting teeth overlap each other in a radial direction In both clutch device from <CIT> and <CIT> are shown flange side recessed portion which are disposed in the gap between the fitting teeth.

Such a clutch device including the clutch center and the pressure plate assembled together tends to be relatively heavy because the clutch device holds a plurality of input-side rotating plates and a plurality of output-side rotating plates. Therefore, a vehicle including the clutch device such as a motorcycle or the like may also be heavy. In consideration of the running performance (e.g., gas mileage), it is preferred that the clutch device is lightweight. However, the clutch device also needs to have a certain level of rigidity.

Preferred embodiments of the present invention provide clutch devices each including a pressure plate that is sufficiently rigid and lightweight, motorcycles each including such a clutch device, and methods for producing the pressure plates.

A clutch device according to a preferred embodiment of the present invention is a clutch device to allow or block transfer of a rotation driving force of an input shaft to an output shaft. The clutch device includes a clutch center housed in a clutch housing holding a plurality of input-side rotating plates rotationally drivable by rotational driving of the input shaft, the clutch center holding a portion of a plurality of output-side rotating plates alternately arranged with the input-side rotating plates, the clutch center being rotationally drivable together with the output shaft, and a pressure plate movable toward or away from the clutch center and rotatable with respect to the clutch center, the pressure plate being capable of pressing the input-side rotating plates and the output-side rotating plates. The pressure plate includes a body, a flange extending radially outward from an outer circumferential edge of the body, a plurality of pressure-side fitting teeth projecting in a first direction from a first direction-side surface of the flange, holding another portion of the plurality of output-side rotating plates, and being arranged in a circumferential direction, where the first direction is a direction in which the pressure plate moves toward the clutch center, and a second direction is a direction in which the pressure plate moves away from the clutch center, and flange-side recessed portions recessed in the first direction from a second direction-side surface of the flange. As seen in an axial direction of the output shaft, the flange-side recessed portions at least partially overlap the pressure-side fitting teeth.

According to a clutch device of a preferred embodiment of the present invention, the pressure plate includes the flange-side recessed portions recessed in the first direction from the second direction-side surface of the flange. As can be seen, the pressure plate includes the flange-side recessed portions, which makes the pressure plate lightweight. In addition, as seen in the axial direction of the output shaft, the flange-side recessed portions at least partially overlap the pressure-side fitting teeth. As described above, the pressure-side fitting teeth are located on portions of the first direction-side surface of the flange. Portions of the second direction-side surface of the flange, that correspond to such portions of the first direction-side surface are relatively rigid. Therefore, the flange-side recessed portions are located in the portions of the second direction-side surface of the flange that overlap the pressure-side fitting teeth, so that the pressure plate is reliably rigid and is also lightweight.

A method for producing a pressure plate according to a preferred embodiment of the present invention is a method for producing a pressure plate including a body, a flange extending radially outward from an outer circumferential edge of the body, a plurality of pressure-side fitting teeth projecting from a front surface of the flange, holding output-side rotating plates, and being arranged in a circumferential direction, and flange-side recessed portions located in a back surface of the flange. The method includes preparing a mold including a fixed mold and a movable mold allowed to approach, or to be separated from, the fixed mold, causing the movable mold to approach the fixed mold to close the mold, filling a molding space formed by the movable mold and the fixed mold with a metal material, cooling and solidifying the metal material to form the pressure plate by molding and then separating the movable mold from the fixed mold to open the mold, and detaching the pressure plate from the movable mold by pushing a core pin against a portion of the back surface of the flange of the pressure plate fixed to the movable mold that overlaps one of the pressure-side fitting teeth as seen in a mold moving direction that is a direction in which the movable mold is moved with respect to the fixed mold.

According to a method for producing a pressure plate of a preferred embodiment of the present invention, in the detaching, the core pins are pushed against the portions of the back surface of the flange of the pressure plate fixed to the movable mold that overlap the pressure-side fitting teeth as seen in the mold moving direction. As described above, the pressure-side fitting teeth are located on portions of the front surface of the flange. Portions of the back surface of the flange that correspond to such portions of the front surface are relatively rigid. Therefore, the core pins are pushed against the portions of the back surface that overlap the pressure-side fitting teeth as seen in the mold moving direction, so that the pressure plate is detached from the movable mold without being deformed while the flange-side recessed portions are provided in the back surface of the flange.

Preferred embodiments of the present invention provide clutch devices each including a pressure plate that is sufficiently rigid and lightweight, and motorcycles each including such a clutch device, and methods for producing the pressure plates.

Preferred embodiments of clutch devices according to 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 signs, 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 or the like, for example. The clutch device <NUM> allows or blocks 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 blocks 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 located between the engine and a transmission.

In the following description, a direction in which a pressure plate <NUM> and a clutch center <NUM> of the clutch device <NUM> are aligned will be referred to as a direction 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. A circumferential direction of the clutch center <NUM> and the pressure plate <NUM> will be referred to as a circumferential direction S. Regarding two of pressure-side cam portions <NUM> located along the circumferential direction S, a circumferential direction from one pressure-side cam portion <NUM> to the other pressure-side cam portion <NUM> will be referred to as a first circumferential direction S1 (see <FIG>), and a circumferential direction 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, an axial direction of the output shaft <NUM>, an axial direction of a clutch housing <NUM>, an axial direction of the clutch center <NUM>, and an axial direction of the pressure plate <NUM> are the same as the direction 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 output shaft <NUM> is a hollow shaft. One end of the output shaft <NUM> rotatably supports an input gear <NUM> described below and the clutch housing <NUM> through a needle bearing 15A. The output shaft <NUM> securely supports the 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 with a transmission (not shown) of a motorcycle, 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 <FIG>) coupled with a clutch operation lever (not shown) of the motorcycle, and slides in the hollow portion <NUM> by an operation of the clutch operation lever and presses the 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 with a release bearing <NUM> provided in 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 in the second direction D2 from an edge of the bottom wall <NUM>. The clutch housing <NUM> holds a plurality of input-side rotating plates <NUM>.

As illustrated in <FIG>, the input gear <NUM> is located on the bottom wall <NUM> of the clutch housing <NUM>. The input gear <NUM> is secured 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 drivable together with the clutch housing <NUM>, independently of the output shaft <NUM>.

The input-side rotating plates <NUM> are rotationally drivable by rotational driving of the input shaft. As illustrated in <FIG>, the input-side rotating plates <NUM> are held on an inner circumferential surface of the side wall <NUM> of the clutch housing <NUM>. The input-side rotating plates <NUM> are held by 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 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 molded 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 front and back surfaces of each 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 located. The clutch center <NUM> includes a cylindrical body <NUM> and a flange <NUM> extending radially outward from an outer circumferential 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 direction D. The clutch center <NUM> is rotationally drivable together with the output shaft <NUM>.

As illustrated in <FIG>, the body <NUM> includes a ring-shaped base wall <NUM>, an outer circumferential wall <NUM> located radially outward of the base wall <NUM> and extending in the second direction D2, an output shaft holding portion <NUM> located at the center of the base wall <NUM>, a plurality of center-side cam portions <NUM> connected with the base wall <NUM> and the outer circumferential 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 circumferential surface 50A, of the output shaft holding portion <NUM>, defining the insertion hole <NUM> has a plurality of spline grooves formed along an axial direction thereof. The output shaft <NUM> is coupled with the output shaft holding portion <NUM>.

As illustrated in <FIG>, the outer circumferential wall <NUM> of the clutch center <NUM> is located radially outward of the output shaft holding portion <NUM>. An outer circumferential surface 45A of the outer circumferential wall <NUM> has a spline fitting portion <NUM> formed thereat. The spline fitting portion <NUM> includes a plurality of center-side fitting teeth <NUM> extending in the axial direction of the clutch center <NUM> along the outer circumferential surface 45A of the outer circumferential 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 direction of the clutch center <NUM>, and oil flow holes <NUM>. The center-side fitting teeth <NUM> hold the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. The plurality of center-side fitting teeth <NUM> are arranged in the circumferential direction S. The plurality of center-side fitting teeth <NUM> are arranged at an equal interval in the circumferential direction S. The plurality of center-side fitting teeth <NUM> have the same shape. The center-side fitting teeth <NUM> project radially outward from the outer circumferential surface 45A of the outer circumferential wall <NUM>. The number of the center-side fitting teeth <NUM> may be a multiple of the number of the center-side cam portions <NUM>. In this preferred embodiment, the center-side cam portions <NUM> are provided in the number of three, and the center-side fitting teeth <NUM> are provided in the number of <NUM>, as described below. The number of the center-side fitting teeth <NUM> does not need to be a multiple of the number of the center-side cam portions <NUM>. The oil flow holes <NUM> penetrate the outer circumferential wall <NUM> in the radial direction. The oil flow holes <NUM> are 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 to the side of the center-side cam portions <NUM>. The oil flow holes <NUM> are formed to the side of center-side slipper cam surfaces <NUM> of the center-side cam portions <NUM>. The oil flow holes <NUM> are formed ahead of the center-side slipper cam surfaces <NUM> in the first circumferential direction S1. The oil flow holes <NUM> are formed ahead of bosses <NUM> described below in the second circumferential direction S2. In this preferred embodiment, three oil flow holes <NUM> are formed at each of three positions in the circumferential direction S of the outer circumferential wall <NUM>. The oil flow holes <NUM> are located at an equal interval in the circumferential direction S. The oil flow holes <NUM> cause the inside and the outside of the clutch center <NUM> to communicate with each other. The oil flow holes <NUM> allow clutch oil, flowing out from the output shaft <NUM> into the clutch center <NUM>, to flow to the outside of the clutch center <NUM>. In this preferred embodiment, the oil flow holes <NUM> allow the clutch oil, flowing on an inner circumferential surface 45B of the outer circumferential wall <NUM>, to flow to the outside of the clutch center <NUM>. At least a portion of the oil flow holes <NUM> is provided at a position facing a pressure-side fitting portion <NUM> described below.

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> and the spline grooves <NUM> of the clutch center <NUM> by spline fitting. Another portion of the output-side rotating plates <NUM> is held by pressure-side fitting teeth <NUM> (see <FIG>; described below) of the pressure plate <NUM>. The output-side rotating plates <NUM> are displaceable along the axial direction 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 molded by punching a thin plate of an SPCC material into a ring shape. Front and back surfaces of each of the output-side rotating plates <NUM> have grooves with depths of several micrometers to several tens of micrometers to hold clutch oil. The front and back surfaces of each of the output-side rotating plates <NUM> are subjected to a surface hardening treatment to enhance abrasion resistance thereof. The friction members, described above as being provided on the input-side rotating plates <NUM>, may be provided on the output-side rotating plates <NUM> instead of on 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 truncated quadrangular pyramid shape including a cam surface including a slope acting as an Assist & Slipper (registered trademark) mechanism. The cam surface as the Assist & Slipper (registered trademark) mechanism generates an assist torque as a force 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 separating the input-side rotating plates <NUM> and the output-side rotating plates <NUM> from each other on an early stage and shifting these plates into a half-clutch state. The center-side cam portions <NUM> project ahead of the base wall <NUM> in the second direction D2. As illustrated in <FIG>, the center-side cam portions <NUM> are arranged at an equal interval in the circumferential direction 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 a 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 such 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>, when the clutch center <NUM> rotates with respect to the pressure plate <NUM>. In this preferred embodiment, when this force is generated, the position of the pressure plate <NUM> with respect 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 decrease the pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM>, when the clutch center <NUM> rotates with respect to the pressure plate <NUM>. Regarding two of the center-side cam portions <NUM> adjacent to each other in the circumferential direction 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 direction S.

As illustrated in <FIG>, the clutch center <NUM> includes the plurality of (three in this preferred embodiment) bosses <NUM>. The bosses <NUM> support the pressure plate <NUM>. The plurality of bosses <NUM> are arranged at an equal interval in the circumferential direction 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 located on the base wall <NUM>. The bosses <NUM> each have a screw hole <NUM>, into which a bolt <NUM> (see <FIG>) is inserted. The screw hole <NUM> extends in the axial direction of the clutch center <NUM>.

As illustrated in <FIG> and <FIG>, the clutch center <NUM> has 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 direction D. Each of the center-side cam holes <NUM> extends from a position to the side of the output shaft holding portion <NUM> to the outer circumferential wall <NUM>. The 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>. As seen in the axial direction of the clutch center <NUM>, the center-side assist cam surface 60A overlaps a portion of the center-side cam hole <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 located ahead of the center-side cam portions <NUM> in the second direction D2. The center-side fitting portion <NUM> is formed on the inner circumferential surface 45B of the outer circumferential wall <NUM>. The center-side fitting portion <NUM> is configured to be slidably outserted onto the pressure-side fitting portion <NUM> (see <FIG>) described below. 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 (see <FIG>) 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 below. 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>, for example. 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, for example.

As illustrated in <FIG>, the pressure plate <NUM> is movable toward or away from the clutch center <NUM> and rotatable with respect to the clutch center <NUM>. The pressure plate <NUM> is configured to be capable of pressing the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. The pressure plate <NUM> is located concentrically with the clutch center <NUM> and the clutch housing <NUM>. The pressure plate <NUM> includes a body <NUM>, and a flange <NUM> connected with an outer circumferential edge, on the side of the second direction D2, of the body <NUM> 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>.

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

As illustrated in <FIG>, the flange <NUM> extends radially outward from the outer circumferential edge of the body <NUM>. In this preferred embodiment, the flange <NUM> extends radially outward from an outer circumferential edge of the pressure-side fitting portion <NUM>. The flange <NUM> has a front surface 98A and a back surface 98B (see <FIG>). The front surface 98A applies a pressing force to the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. The front surface 98A contacts the input-side rotating plates <NUM> and the output-side rotating plates <NUM> directly or indirectly. The front surface 98A and the flange <NUM> of the clutch center <NUM> sandwich the input-side rotating plates <NUM> and the output-side rotating plates <NUM> therebetween. The front surface 98A is an example of first direction-side surface. The back surface 98B is an example of second direction-side surface.

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 flowing out of the distal end 15T of the output shaft <NUM>.

Each of the pressure-side cam portions <NUM> has a truncated quadrangular pyramid shape having a cam surface including a slope acting as an Assist & Slipper (registered trademark) mechanism. The cam surface as the Assist & Slipper (registered trademark) mechanism slides on the center-side cam portion <NUM> and generates an assist torque or a slipper torque. The pressure-side cam portion <NUM> projects ahead of the flange <NUM> in the first direction D1. As illustrated in <FIG>, the pressure-side cam portions <NUM> are arranged at an equal interval in the circumferential direction 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 portions <NUM> are 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 is configured to be contactable with the center-side assist cam surface 60A. The pressure-side assist cam surface 90A is configured to generate a force in such 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>, when the pressure plate <NUM> rotates with respect to the clutch center <NUM>. The pressure-side slipper cam surface <NUM> is configured to be contactable 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 decrease the pressing force (contact pressure force) between the input-side rotating plates <NUM> and the output-side rotating plates <NUM>, when the pressure plate <NUM> rotates with respect to the clutch center <NUM>. Regarding two of the pressure-side cam portions <NUM> adjacent to each other in the circumferential direction 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 direction S.

Effects of the center-side cam portions <NUM> and the pressure-side cam portions <NUM> will now be described. Referring to <FIG>, 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>. Thus, with the effects of the center-side assist cam surface 60A and the pressure-side assist cam surface 90A, a force in the 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.

By contrast, referring to <FIG>, 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>. 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 to cancel the contact pressure force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM>. In this manner, inconveniences regarding the engine and the transmission caused by the back torque are avoided.

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>. Each of the pressure-side cam holes <NUM> extends from a position to the side of the cylindrical portion <NUM> to a position radially outward of the pressure-side fitting portion <NUM>. The pressure-side cam hole <NUM> is located between adjacent ones of the pressure-side cam portions <NUM> while penetrating the body <NUM>. The pressure-side cam hole <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> while penetrating the body <NUM>. As illustrated in <FIG> and <FIG>, as seen in the axial direction of the pressure plate <NUM>, the pressure-side assist cam surface 90A overlaps a portion of the pressure-side cam hole <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 to the first direction D1. Each of the spring housing portions <NUM> has an oval cross-section. The spring housing portion <NUM> houses a pressure spring <NUM> (see <FIG>). The spring housing portion <NUM> has an insertion hole <NUM>, into which the boss <NUM> (see <FIG>) is inserted. That is, the insertion hole <NUM> penetrates the pressure-side cam portion <NUM>. The insertion hole <NUM> has an oval cross-section.

As illustrated in <FIG>, the pressure springs <NUM> are housed in the spring housing portions <NUM>. Each of the pressure springs <NUM> is held by the boss <NUM> inserted into the insertion hole <NUM> of the spring housing portion <NUM>. The pressure spring <NUM> biases the pressure plate <NUM> toward the clutch center <NUM> (i.e., in the first direction D1). The pressure spring <NUM> is, for example, a coil spring formed of helically wound spring steel.

As illustrated in <FIG>, the pressure-side fitting portion <NUM> is provided in the main body <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 second direction D2. The pressure-side fitting portion <NUM> is configured to be slidably insertable into 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> on the flange <NUM>. The pressure-side fitting teeth <NUM> hold the input-side rotating plates <NUM> and 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 located on the front surface 98A of the flange <NUM>. The pressure-side fitting teeth <NUM> project in the first direction D1 from the flange <NUM>. The plurality of pressure-side fitting teeth <NUM> are arranged in the circumferential direction S. The plurality of pressure-side fitting teeth <NUM> are arranged at an equal interval in the circumferential direction S. In this preferred embodiment, a portion of the pressure-side fitting teeth <NUM> is removed, and thus the interval between the pressure-side fitting teeth <NUM> sandwiching such a removed portion of the pressure-side fitting teeth <NUM> is longer. The other pressure-side fitting teeth <NUM> are arranged at an equal interval.

As illustrated in <FIG>, the pressure plate <NUM> includes a plurality of flange-side recessed portions <NUM> located in the back surface 98B of the flange <NUM>. The flange-side recessed portions <NUM> are recessed in the first direction D1 from the back surface 98B of the flange <NUM>. The flange-side recessed portions <NUM> are recessed from the back surface 98B by, for example, about <NUM> to about <NUM>. The flange-side recessed portions <NUM> may be recessed from the back surface 98B by about <NUM> to about <NUM>, for example. Alternatively, the flange-side recessed portions <NUM> may be recessed from the back surface 98B by a depth deeper than about <NUM>, for example. The flange-side recessed portions <NUM> are, for example, cylindrical or substantially cylindrical. There is no specific limitation on the shape of the flange-side recessed portions <NUM>. As illustrated in <FIG>, as seen in the axial direction of the output shaft <NUM>, the flange-side recessed portions <NUM> at least partially overlap the pressure-side fitting teeth <NUM>. The flange-side recessed portions <NUM> include first flange-side recessed portions 96A, second flange-side recessed portions 96B, and third flange-side recessed portions 96C. The first flange-side recessed portions 96A are located radially outward of the pressure-side cam holes <NUM>. In this preferred embodiment, the pressure plate <NUM> includes three first flange-side recessed portions 96A. The first flange-side recessed portions 96A are located at an equal interval in the circumferential direction S. The second flange-side recessed portions 96B are located radially outward of the spring housing portions <NUM>. In this preferred embodiment, two second flange-side recessed portions 96B are provided for one spring housing portion <NUM>. One of such two second flange-side recessed portions 96B is provided radially outward of an end 84HA, on one side in the circumferential direction S, of the spring housing portion <NUM>, and the other of such two second flange-side recessed portions 96B is provided radially outward of an end 84HB, on the other side in the circumferential direction S, of the spring housing portion <NUM>. The third flange-side recessed portions 96C are located between the first flange-side recessed portions 96A and the second flange-side recessed portions 96B in the circumferential direction S. The third flange-side recessed portions 96C are located ahead of the pressure-side cam holes <NUM> in the first circumferential direction S1. The third flange-side recessed portions 96C are located ahead of the spring housing portions <NUM> in the second circumferential direction S2. As illustrated in <FIG>, the third flange-side recessed portions 96C are located on extended lines LM extended from rib portions <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other. The extended lines LM pass, for example, a center 80C of the cylindrical portion <NUM> and body-side recessed portions <NUM> described below. Herein, the rib portions <NUM> are portions of the body <NUM> that are located between the spring housing portions <NUM> and the pressure-side cam holes <NUM> in the circumferential direction S, and extend in the radial direction. As seen in a plan view, the rib portions <NUM> overlap, for example, the pressure-side slipper cam surfaces <NUM>. The first flange-side recessed portions 96A, the second flange-side recessed portions 96B and the third flange-side recessed portions 96C are located on the same circumference. The flange-side recessed portions <NUM> are formed by, for example, core pins <NUM> (see <FIG>) being pushed against the back surface 98B of the flange <NUM> as described below. The flange-side recessed portions <NUM> may be formed by cutting.

As illustrated in <FIG>, the pressure plate <NUM> includes the plurality of body-side recessed portions <NUM> located in a back surface 72B of the body <NUM>. The body-side recessed portions <NUM> are recessed in the first direction D1 from the back surface 72B of the body <NUM>. The body-side recessed portions <NUM> are recessed from the back surface 72B by, for example, about <NUM> to about <NUM>. The body-side recessed portions <NUM> may be recessed from the back surface 72B by about <NUM> to about <NUM>, for example. Alternatively, the body-side recessed portions <NUM> may be recessed from the back surface 72B by a depth deeper than about <NUM>, for example. As illustrated in <FIG>, as seen in the axial direction of the output shaft <NUM>, the body-side recessed portions <NUM> at least partially overlap the pressure-side cam portions <NUM>. As seen in the axial direction of the output shaft <NUM>, the body-side recessed portions <NUM> at least partially overlap the pressure-side slipper cam surfaces <NUM>. The body-side recessed portions <NUM> are provided between the pressure-side cam holes <NUM> and the spring housing portions <NUM> in the circumferential direction S. The body-side recessed portions <NUM> are located ahead of the pressure-side cam holes <NUM> in the first circumferential direction S1. The body-side recessed portions <NUM> are located ahead of the spring housing portions <NUM> in the second circumferential direction S2. The plurality of body-side recessed portions <NUM> are located on the same circumference. The plurality of body-side recessed portions <NUM> are located at an equal interval in the circumferential direction S. The body-side recessed portions <NUM> are located radially inward of the flange-side recessed portions <NUM>.

<FIG> is a plan view illustrating a state where the clutch center <NUM> and the pressure plate <NUM> are assembled. In the state illustrated in <FIG>, the pressure-side assist cam surfaces 90A and the center-side assist cam surfaces 60A are not in contact with each other, and the pressure-side slipper cam surfaces <NUM> and the center-side slipper cam surfaces <NUM> are not in contact with each other. This is a state where the pressure plate <NUM> is closest to the clutch center <NUM>. In the state illustrated in <FIG> (assembly state), a distance L1 in the circumferential direction S between each boss <NUM> and an end 84HA, on the side of the pressure-side assist cam surface 90A (i.e., on the side of the first circumferential direction S1), of the insertion hole <NUM> is shorter than a distance L2 in the circumferential direction S between the boss <NUM> and an end 84HB, on the side of the pressure-side slipper cam surface <NUM> (i.e., on the side of the second circumferential direction S2), of the insertion hole <NUM>.

As illustrated in <FIG>, the stopper plate <NUM> is contactable with 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 secured to the bosses <NUM> of the clutch center <NUM> with the bolts <NUM>. The pressure plate <NUM> is secured by the bolts <NUM> fastened to the bosses <NUM> through the stopper plate <NUM> in a state where the bosses <NUM> of the clutch center <NUM> and the pressure springs <NUM> are located in the spring housing portions <NUM>. The stopper plate <NUM> is substantially triangular as seen in a plan view.

When the pressure plate <NUM> is in 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 by 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 in contact with the stopper plate <NUM>, the pressure springs <NUM> are separated from 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. The 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 through the oil flow holes <NUM>. The clutch oil is distributed from the outside of the clutch center <NUM> to the inside of the clutch center <NUM> through the hollow portion <NUM> of the output shaft <NUM> and through the pressure-side cam holes <NUM>. The clutch oil suppresses 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.

Now, a method for producing the pressure plate <NUM> according to a preferred embodiment of the present disclosure will be described. <FIG> is a flowchart illustrating a method for producing the pressure plate <NUM>. As illustrated in <FIG>, the method for producing the pressure plate <NUM> includes a preparation step S10, a mold clamping step S20, a filling step S30, a mold opening step S40, and a detachment step S50. In this preferred embodiment, as illustrated in <FIG>, the pressure plate <NUM> is produced by use of a mold <NUM> including a fixed mold <NUM> and a movable mold <NUM>. In <FIG>, a direction in which the movable mold <NUM> moves with respect to the fixed mold <NUM> will be referred to as a mold moving direction P, a direction in which the movable mold <NUM> approaches the fixed mold <NUM> will be referred to as a direction P1, and a direction in which the movable mold <NUM> is separated away from the fixed mold <NUM> will be referred to as a direction P2.

First, in the preparation step S10, as illustrated in <FIG>, the mold <NUM> including the fixed mold <NUM> and the movable mold <NUM> allowed to approach, or to be separated from, the fixed mold <NUM> is prepared. The fixed mold <NUM> has a cavity <NUM> formed therein, which is used to form the body <NUM>, the pressure-side fitting teeth <NUM> and the like of the pressure plate <NUM>. The movable mold <NUM> has a core <NUM> formed therein, which is used to form the flange <NUM> and the like of the pressure plate <NUM>.

Next, in the mold clamping step S20, as illustrated in <FIG>, the movable mold <NUM> is caused to approach the fixed mold <NUM> to close the mold <NUM>. That is, the movable mold <NUM> is moved in the direction P1, and thus the fixed mold <NUM> is closed with the movable mold <NUM>. As a result, a molding space <NUM>, in which the pressure plate <NUM> is to be formed by molding, is demarcated by the cavity <NUM> and the core <NUM>.

Next, in the filling step S30, the molding space <NUM> formed by the movable mold <NUM> and the fixed mold <NUM> is filled with a metal material. The metal material may be, for example, an aluminum alloy. The metal material is injected, in a melted state, into the molding space <NUM> through an injection opening (not shown) provided in the fixed mold <NUM>, and thus fills the molding space <NUM>.

Next, in the mold opening step S40, the metal material is cooled to be solidified to form the pressure plate <NUM> by molding, and then the movable mold <NUM> is separated from the fixed mold <NUM> to open the mold <NUM>. That is, as illustrated in <FIG>, the movable mold <NUM> is moved in the direction P2 to be separated away from the fixed mold <NUM>. In this state, the pressure plate <NUM> formed by molding is fixed to the movable mold <NUM>.

Next, in the detachment step S50, the pressure plate <NUM> is detached from the movable mold <NUM>. This is performed by pressing the core pins <NUM> to portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that overlap the pressure-side fitting teeth <NUM> as seen in the mold moving direction P (i.e., the axial direction of the output shaft <NUM>). As illustrated in <FIG>, the movable mold <NUM> has insertion holes <NUM> formed therein, into which the core pins <NUM> are insertable. The core pins <NUM> are moved in the direction P1 in <FIG>, and as a result, the pressure plate <NUM> is detached from the movable mold <NUM> while the flange-side recessed portions <NUM> and the body-side recessed portions <NUM> described above are formed.

In the detachment step S50, for example, the core pins <NUM> are pushed against portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that are radially outward of the pressure-side cam holes <NUM>. As a result, the first flange-side recessed portions 96A are formed in the back surface 98B of the flange <NUM>. In the detachment step S50, for example, the core pins <NUM> are pushed against portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that are radially outward of the spring housing portions <NUM>. More specifically, in the detachment step S50, for example, the core pins <NUM> are pushed against portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that are radially outward of the ends 84HA, on one side in the circumferential direction S, of the spring housing portions <NUM> and are radially outward of the ends 84HB, on the other side in the circumferential direction S, of the spring housing portions <NUM>. As a result, the second flange-side recessed portions 96B are formed in the back surface 98B of the flange <NUM>. In the detachment step S50, for example, the core pins <NUM> are pushed against portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that are between the pressure-side cam holes <NUM> and the spring housing portions <NUM> in the circumferential direction S. As a result, the third flange-side recessed portions 96C are formed in the back surface 98B of the flange <NUM>. In the detachment step S50, for example, the core pins <NUM> are pushed against portions of the back surface 72B of the body <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that overlap the pressure-side cam portions <NUM> as seen in the mold moving direction P. More specifically, in the detachment step S50, the core pins <NUM> are pushed against portions of the back surface 72B of the body <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that overlap the pressure-side slipper cam surfaces <NUM> as seen in the mold moving direction P. As a result, the body-side recessed portions <NUM> are formed in the back surface 72B of the body <NUM>.

An operation of the clutch device <NUM> according to this preferred embodiment will now be described. As described above, the clutch device <NUM> is located between the engine and the transmission of the motorcycle, and allows or blocks transfer of a rotation driving force of the engine to the transmission by an operation by a driver on a clutch operation lever.

In the case where the driver of the motorcycle does not operate the clutch operation lever, the clutch device <NUM> operates as follows. 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 the clutch center <NUM> 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 flowing in the hollow portion <NUM> of the output shaft <NUM> and then flowing out of the distal end 15T of the output shaft <NUM> is dropped or spattered into 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, the clutch oil flows to the outside of the clutch center <NUM> through the oil flow holes <NUM>. The clutch oil also flows to the outside of the clutch center <NUM> through the gap between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM>. Then, the clutch oil flowing to the outside of the clutch center <NUM> is supplied to the input-side rotating plates <NUM> and the output-side rotating plates <NUM>.

By contrast, when the driver of the motorcycle operates the clutch operation lever in the clutch-ON state, the clutch device <NUM> operates as follows. 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> (in the second direction D2) against a biasing force of the pressure springs <NUM>. Accordingly, the clutch center <NUM> enters a clutch-OFF state, in which the 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, the rotation driving force of the engine is blocked and is not transferred to the clutch center <NUM>.

In the clutch-OFF state, clutch oil flowing in the hollow portion <NUM> of the output shaft <NUM> and then flowing out of the distal end 15T of the output shaft <NUM> is guided into the clutch center <NUM> in the same manner as in the clutch-ON state. At this point, the pressure plate <NUM> is separated from the clutch center <NUM>, and thus, the amount of fitting between the center-side fitting portion <NUM> and the pressure-side fitting portion <NUM> decreases. As a result, the clutch oil in the cylindrical portion <NUM> more actively flows to the outside of the clutch center <NUM>, and is distributed to various portions in the clutch device <NUM>. In particular, the 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 releases the clutch operation lever in the clutch-OFF state, the pressure plate <NUM> is released from the state of being pressed by the clutch release mechanism (not shown) through the push member 16B, and thus, the pressure plate <NUM> is displaced in a direction toward the clutch center <NUM> (in the first direction D1) by a biasing force of the pressure springs <NUM>.

As described above, in the clutch device <NUM> according to this preferred embodiment, the pressure plate <NUM> includes the flange-side recessed portions <NUM> recessed in the first direction D1 from a second direction D2-side surface of the flange <NUM> (in this preferred embodiment, the back surface 98B). As can be seen, the pressure plate <NUM> includes the flange-side recessed portions <NUM> formed therein. This makes the pressure plate <NUM> lightweight. In addition, as seen in the axial direction of the output shaft <NUM>, the flange-side recessed portions <NUM> at least partially overlap the pressure-side fitting teeth <NUM>. As described above, the pressure-side fitting teeth <NUM> are located on a first direction D1-side surface (in this preferred embodiment, the front surface 98A) of the flange <NUM>. Portions of the second direction D2-side surface of the flange <NUM>, that correspond to such portions of the front surface 98A are relatively rigid. Therefore, the flange-side recessed portions <NUM> are provided in the portions of the back surface 98B, that overlap the pressure-side fitting teeth <NUM>, so that the pressure plate <NUM> is made rigid with certainty and also lightweight.

In the clutch device <NUM> according to this preferred embodiment, the flange-side recessed portions <NUM> include the first flange-side recessed portions 96A, which are located radially outward of the pressure-side cam holes <NUM>. According to the above-described preferred embodiment, a stress applied to the portions radially outward of the pressure-side cam holes <NUM> is relatively small. Therefore, the first flange-side recessed portions 96A are provided in such portions, so that the pressure plate <NUM> is allowed to provide a certain level of performance and also to be lightweight.

In the clutch device <NUM> according to this preferred embodiment, the flange-side recessed portions <NUM> include the second flange-side recessed portions 96B, which are located radially outward of the spring housing portions <NUM>. According to the above-described preferred embodiment, a stress applied to the portions radially outward of the spring housing portions <NUM> is relatively small. Therefore, the second flange-side recessed portions 96B are provided in such portions, so that the pressure plate <NUM> is allowed to provide a certain level of performance and also to be lightweight.

In the clutch device <NUM> according to this preferred embodiment, the second flange-side recessed portions 96B are located radially outward of the ends 84HA, on one side in the circumferential direction S, of the spring housing portions <NUM>, and radially outward of the ends 84HB, on the other side in the circumferential direction S, of the spring housing portions <NUM>. According to the above-described preferred embodiment, the pressure plate <NUM> is made more lightweight.

In the clutch device <NUM> according to this preferred embodiment, the pressure plate <NUM> includes the plurality of pressure-side cam portions <NUM> provided in the body <NUM> and the body-side recessed portions <NUM> recessed in the first direction D1 from the second direction D2-side surface (in this preferred embodiment, the back surface 98B) of the body <NUM>. The plurality of pressure-side cam portions <NUM> each include at least one of the pressure-side assist cam surface 90A and the pressure-side slipper cam surface <NUM>. The pressure-side assist cam surface 90A generates a force in such 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>, when the pressure plate <NUM> rotates with respect to the clutch center <NUM>. The pressure-side slipper cam surface <NUM> separates the pressure plate <NUM> from the clutch center <NUM>, in order to decrease the pressing force between the input-side rotating plates <NUM> and the output-side rotating plates <NUM>, when the pressure plate <NUM> rotates with respect to the clutch center <NUM>. As seen in the axial direction of the output shaft <NUM>, the body-side recessed portions <NUM> at least partially overlap the pressure-side cam portions <NUM>. As can be seen, the pressure plate <NUM> includes the body-side recessed portions <NUM>, and therefore, is lightweight. In addition, as seen in the axial direction of the output shaft <NUM>, the body-side recessed portions <NUM> at least partially overlap the pressure-side cam portions <NUM>. The portions of the body <NUM> where the pressure-side cam portions <NUM> are provided are relatively rigid. Therefore, the body-side recessed portions <NUM> are provided in the portions of the body <NUM> that overlap the pressure-side cam portions <NUM>, so that the pressure plate <NUM> is made rigid with certainty and also lightweight.

In the clutch device <NUM> according to this preferred embodiment, the pressure-side cam portions <NUM> each include the pressure-side slipper cam surface <NUM>. As seen in the axial direction of the output shaft <NUM>, the body-side recessed portions <NUM> at least partially overlap the pressure-side slipper cam surfaces <NUM>. According to the above-described preferred embodiment, portions of the pressure-side cam portions <NUM>, where the pressure-side slipper cam surfaces <NUM> are provided are relatively rigid. Therefore, the body-side recessed portions <NUM> are provided in the portions of the body <NUM> that overlap the pressure-side slipper cam surfaces <NUM>, so that the pressure plate <NUM> is made rigid with certainty and also lightweight.

In the clutch device <NUM> according to this preferred embodiment, the pressure plate <NUM> includes the cylindrical portion <NUM> provided in the body <NUM> and housing the output shaft <NUM>. The flange-side recessed portions <NUM> are located on the extended lines LM extended from the ribs <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other. According to the above-described preferred embodiment, the portions of the flange <NUM>, that are on the extended lines LM extended from the ribs <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other are relatively rigid. Therefore, the flange-side recessed portions <NUM> are provided on the extended lines extended from the ribs <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other (i.e., on the straight lines LM), so that the pressure plate <NUM> is made rigid with certainty and also lightweight.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, in the detachment step S50, the core pins <NUM> are pushed against the portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM>, that overlap the pressure-side fitting teeth <NUM> as seen in the mold moving direction P. As described above, the pressure-side fitting teeth <NUM> are formed on the front surface 98A of the flange <NUM>. Portions of the back surface 98B of the flange <NUM>, which correspond to such portions of the front surface 98A, are relatively rigid. Therefore, the core pins <NUM> are pushed against the portions of the back surface 98B that overlap the pressure-side fitting teeth <NUM> as seen in the mold moving direction P, so that the pressure plate <NUM> is reduced or prevented from being deformed while the flange-side recessed portions <NUM> are provided in the back surface 98B, and thus the pressure-plate <NUM> is detached from the movable mold <NUM>.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, in the detachment step S50, the core pins <NUM> are pushed against the portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM> that are located radially outward of the pressure-side cam holes <NUM>. According to the above-described preferred embodiment, the core pins <NUM> are pushed against the portions of the back surface 98B of the flange <NUM>, that are located radially outward of the pressure-side cam holes <NUM> so that the portions of the pressure plate <NUM>, that are in the vicinity of the pressure-side cam holes <NUM> are reduced or prevented from being deformed while the flange-side recessed portions <NUM> are provided in such portions, and thus the pressure-plate <NUM> is detached from the movable mold <NUM>.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, in the detachment step S50, the core pins <NUM> are pushed against the portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM> that are located radially outward of the spring housing portions <NUM>. According to the above-described preferred embodiment, the core pins <NUM> are pushed against the portions of the back surface 98B of the flange <NUM> that are located radially outward of the spring housing portions <NUM>, so that the portions of the pressure plate <NUM> that are in the vicinity of the spring housing portions <NUM> are reduced or prevented from being deformed while the flange-side recessed portions <NUM> are provided in such portions, and thus the pressure-plate <NUM> is detached from the movable mold <NUM>.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, in the detachment step S50, the core pins <NUM> are pushed against the portions of the back surface 98B of the flange <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM> that are located radially outward of the ends 84HA on one side in the circumferential direction S of the spring housing portions <NUM> and are radially outward of the ends 84HB on the other side in the circumferential direction S, of the spring housing portions <NUM>. According to the above-described preferred embodiment, the portions of the pressure plate <NUM> that are in the vicinity of the spring housing portions <NUM> are further reduced or prevented from being deformed.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, in the detachment step S50, the core pins <NUM> are pushed against the portions of the back surface 72B of the body <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM> that overlap the pressure-side cam portions <NUM> as seen in the mold moving direction P. The portions of the back surface 72B of the body <NUM> that overlap the pressure-side cam portions <NUM> as seen in the mold moving direction P are relatively rigid. Therefore, the core pins <NUM> are pushed against the portions of the back surface 72B that overlap the pressure-side cam portions <NUM> as seen in the mold moving direction P so that the pressure plate <NUM> is reduced or prevented from being deformed while the body-side recessed portions <NUM> are provided in the back surface 72B of the body <NUM>, and thus the pressure-plate <NUM> is detached from the movable mold <NUM>.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, in the detachment step S50, the core pins <NUM> are pushed against the portions of the back surface 72B of the body <NUM> of the pressure plate <NUM> fixed to the movable mold <NUM> that overlap the pressure-side slipper cam surfaces <NUM> as seen in the mold moving direction P. According to the above-described preferred embodiment, the portions of the back surface 72B of the body <NUM> where the pressure-side slipper cam surfaces <NUM> are located are relatively rigid. Therefore, the core pins <NUM> are pushed against the portions of the back surface 72B that overlap the pressure-side slipper cam surfaces <NUM> as seen in the mold moving direction P, so that that the pressure plate <NUM> is reduced or prevented from being deformed while the body-side recessed portions <NUM> are provided in the back surface 72B of the body <NUM>, and thus the pressure-plate <NUM> is detached from the movable mold <NUM>.

With the method for producing the pressure plate <NUM> according to this preferred embodiment, the pressure plate <NUM> includes the cylindrical portion <NUM> provided in the body <NUM> and housing the output shaft <NUM>. The portions of the back surface 98B of the flange <NUM> that overlap the pressure-side fitting teeth <NUM> as seen in the mold moving direction P are located on the extended lines LM extended from the ribs <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other. According to the above-described preferred embodiment, the portions of the flange <NUM> that are on the extended lines extended from the ribs <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other are relatively rigid. Therefore, the core pins <NUM> are pushed against the portions of the flange <NUM> that are on the extended lines extended from the ribs <NUM> connecting the cylindrical portion <NUM> and the flange <NUM> to each other (i.e., on the straight lines LM), so that the pressure plate <NUM> is reduced or prevented from being deformed while the flange-side recessed portions <NUM> are provided in the back surface 98B of the flange <NUM>, and thus the pressure-plate <NUM> is detached from the movable mold <NUM>.

Some preferred embodiments of the present disclosure have been described. The above-described embodiments are merely examples, and the present disclosure may be carried out in any of various other forms.

In the above-described preferred embodiments, the center-side cam portions <NUM> each include the center-side assist cam surface 60A and the center-side slipper cam surface <NUM>. It is sufficient that the center-side cam portions <NUM> each include at least one of the center-side assist cam surface 60A and the center-side slipper cam surface <NUM>.

In the above-described preferred embodiments, the pressure-side cam portions <NUM> each include the pressure-side assist cam surface 90A and the pressure-side slipper cam surface <NUM>. It is sufficient that the pressure-side cam portions <NUM> each include at least one of the pressure-side assist cam surface 90A and the pressure-side slipper cam surface <NUM>.

In the above-described preferred embodiments, the body-side recessed portions <NUM> are located at such positions as to at least partially overlap the pressure-side slipper cam surfaces <NUM> as seen in the axial direction of the output shaft <NUM>. The body-side recessed portions <NUM> are not limited to this. For example, the body-side recessed portions <NUM> may be located at such positions as to at least partially overlap the pressure-side assist cam surfaces 90A as seen in the axial direction of the output shaft <NUM>.

Claim 1:
A clutch device (<NUM>) to allow or block 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>) rotationally drivable by rotational driving of the input shaft, the clutch center (<NUM>) holding a portion of a plurality of output-side rotating plates (<NUM>) alternately arranged with the input-side rotating plates (<NUM>), the clutch center (<NUM>) being rotationally drivable together with the output shaft (<NUM>); and
a pressure plate (<NUM>) movable toward or away from the clutch center (<NUM>) and rotatable with respect to the clutch center (<NUM>), the pressure plate (<NUM>) being capable of pressing the input-side rotating plates (<NUM>) and the output-side rotating plates (<NUM>); wherein
the pressure plate (<NUM>) includes:
a body (<NUM>);
a flange (<NUM>) extending radially outward from an outer circumferential edge of the body (<NUM>);
a plurality of pressure-side fitting teeth (<NUM>) projecting in a first direction (D1) from a first direction-side surface (98A) of the flange (<NUM>), holding another portion of the plurality of output-side rotating plates (<NUM>), and being arranged in a circumferential direction (S), where the first direction (D1) is a direction in which the pressure plate (<NUM>) moves toward the clutch center (<NUM>), and a second direction (D2) is a direction in which the pressure plate (<NUM>) moves away from the clutch center (<NUM>); and
a flange-side recessed portion (<NUM>) recessed in the first direction (D1) from a second direction-side surface (98B) of the flange (<NUM>); and
characterized in that,
as seen in an axial direction of the output shaft (<NUM>), the flange-side recessed portion (<NUM>) at least partially overlaps one of the pressure-side fitting teeth (<NUM>).