Multi-plate clutch device

Abstract

To enable a reduction in crank weight and minimize the impact on rotational speed after clutch engagement. [Solution] In a multi-plate clutch device 71 having a clutch outer 72 to which the rotation of the crankshaft 41 is transmitted, a clutch center 73 that rotates integrally with the main shaft 42, a clutch disc 75 made of aluminum alloy, and a pressure plate 78 biased by a biasing member 77, in which clutch plates 76 made of iron-based material are alternately stacked, the clutch disc 75 is provided with an engaging portion 75k that engages with the clutch center 73, and the clutch plate 76 is provided with an engaging portion 76k that engages with the clutch outer 72, with one end of the clutch plate 76 in the stacking direction in contact with the clutch center 73, and the other end of the clutch plate 76 in the stacking direction in contact with the pressure plate 78.

Description

Technical Field

[0001] The present invention relates to a multi-plate clutch device.

Background Art

[0002] A straddle-type vehicle such as a motorcycle includes a multi-plate clutch device that transmits or blocks the driving force of an engine to a driven body such as a driving wheel. The multi-plate clutch device has a clutch outer to which the rotation of a crankshaft is transmitted, and a clutch center that rotates integrally with a main shaft. A clutch disk using an aluminum alloy as a core material engages with the clutch outer, and a clutch plate made of an iron-based material engages with the clutch center (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since the crank mass is set by a crank weight and a flywheel, it is difficult to reduce the weight of the crankshaft system. Furthermore, in the conventional configuration, the clutch plate using an iron-based material is heavy, and since the clutch plate engages with the main shaft side, it acts as an inertial force with respect to the rise of rotation after clutch engagement, which may affect a quick rise of rotation. The present invention has been made in view of the above circumstances, and an object thereof is to enable weight reduction of a crank weight and suppress an influence on the rise of rotation after clutch engagement.

Means for Solving the Problems

[0005] A multi-plate clutch device is provided, comprising a clutch outer that transmits the rotation of a crankshaft, a clutch center that rotates integrally with the main shaft, a clutch disc made of aluminum alloy, and clutch plates made of iron-based material stacked alternately, with a pressure plate biased by a biasing member to generate frictional force between the clutch disc and the clutch plates, wherein the clutch disc is provided with an engaging portion that engages with the clutch center, the clutch plates are provided with an engaging portion that engages with the clutch outer, the clutch plate at one end in the stacking direction is in contact with the clutch center, and the clutch plate at the other end in the stacking direction is in contact with the pressure plate. [Effects of the Invention]

[0006] According to the present invention, it is possible to reduce the weight of the crank weight and suppress the impact on the rotational start-up after clutch engagement. [Brief explanation of the drawing]

[0007] [Figure 1] This is a side view of a saddle-type vehicle according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is a diagram showing a clutch device. [Figure 4] This diagram shows the clutch disc and clutch plate. [Figure 5] This diagram shows clutch discs made of different friction materials. [Figure 6] This diagram shows the clutch plate from multiple angles. [Figure 7] This diagram shows the clutch plate together with the crankcase, viewed from the side of the vehicle. [Figure 8] This diagram shows the clutch plate together with the clutch center and pressure plate. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. In the description, directions such as front, back, left, right, and up and down refer to directions relative to the vehicle body unless otherwise specified. In each figure, the symbol FR indicates the front of the vehicle body, the symbol UP indicates the top of the vehicle body, and the symbol LH indicates the left side of the vehicle body.

[0009] [Embodiment] Figure 1 is a side view of a saddle-type vehicle 10 according to an embodiment of the present invention. The saddle-type vehicle 10 is a vehicle equipped with a body frame 11, an engine 12 supported by the body frame 11, a front fork 14 that supports the front wheel 13 in a steerable manner, a swing arm 16 that supports the rear wheel 15, and a seat 17 for the rider. The saddle-type vehicle 10 is an off-road vehicle used for off-road driving. Off-road vehicles are required to have high maneuverability and lightweight construction because they operate on harsh terrain such as rocky areas, steep slopes, and areas dotted with obstacles.

[0010] The vehicle frame 11 includes a head pipe 18 located at the front end, a pair of left and right main frames 19 extending downward and rearward from the head pipe 18, and a down tube 20 extending downward from the head pipe 18. The head pipe 18 supports the front fork 14 so that it can be steered. The front fork 14 is fitted with a steering handle 21 for the rider to steer. The steering handle 21 is equipped with a throttle grip for the rider to operate the accelerator, a brake lever for the rider to operate the brakes, and a clutch lever for the rider to operate the clutch.

[0011] A pivot frame 22 is attached to the rear of the main frame 19, and a swingarm 16 is supported on the pivot frame 22 so as to be able to rotate up and down. The engine 12 is supported by the body frame 11 and is positioned in the space enclosed by the main frame 19, pivot frame 22, and down tube 20. The engine 12 drives the rear wheel 15 via a power transmission member 23 consisting of a chain drive mechanism. A fuel tank 24 is supported above the engine 12 and between the left and right pairs of main frames 19.

[0012] Engine 12 includes an internal combustion engine consisting of a single-cylinder, four-stroke engine, and is also referred to as the power unit. The engine 12 comprises a crankcase 31 and a cylinder section 32 that houses the piston of the internal combustion engine. An intake device 33 is connected to the intake port of the cylinder section 32, and an exhaust device 34 is connected to the exhaust port of the cylinder section 32. Inside the crankcase 31, a crankshaft 41 is rotatably supported along the vehicle width direction, and a main shaft 42 and a counter shaft 43 are supported behind the crankshaft 41, parallel to the crankshaft 41.

[0013] Figure 2 is a cross-sectional view of the engine 12 taken from a plane passing through the crankshaft 41, main shaft 42, and counter shaft 43 (section II-II in Figure 1). As shown in Figure 2, the crankcase 31 comprises a first case half 45 and a second case half 46 that are interconnected at mating surfaces perpendicular to the axis C1 passing through the center of the crankshaft 41, forming a crank chamber Ra that houses the crank of the crankshaft 41. The first case half 45 is a case that opens outward in the vehicle width direction (left side) and is covered from the outside in the vehicle width direction by a left crankcase cover 47L (hereinafter referred to as the left cover 47L). The second case half 46 is a case that opens on the opposite side (right side) of the first case half 45 and is covered from the outside in the vehicle width direction (right side) by a right crankcase cover 47R (hereinafter referred to as the right cover 47R). A generator chamber Rb is formed between the left cover 47L and the first case half 45, and a clutch chamber Rc is formed between the right cover 47R and the second case half 46.

[0014] The crankshaft 41 includes a first crank web 41a supported by a bearing 48L on the first case half 45, and a second crank web 41b supported by a bearing 48R on the second case half 46. Further, the crankshaft 41 includes a crank pin 49 that connects the first crank web 41a and the second crank web 41b to each other. The crank pin 49, the first crank web 41a, and the second crank web 41b form a crank between the bearings 48L and 48R. The locations of the bearings 48L and 48R correspond to the "crankshaft support portion" of the present disclosure.

[0015] The crank pin 49 is connected to a piston that slides in the cylinder portion 32 via a connecting rod 50. The connecting rod 50 converts the reciprocating motion of the piston into the rotational motion of the crankshaft 41. A generator (ACG) 61 that generates electricity by the rotation of the crankshaft 41 is provided on the outer side (left side) of the crankcase 31 across the bearing 48L on one side (left side) of the left and right of the crankshaft 41. The generator 61 is a auxiliary machine coaxially connected to the crankshaft 41 and rotates together with the crankshaft 41, and is housed in the generator chamber Rb.

[0016] The generator 61 includes an outer rotor 62 fixed to the left end portion of the crankshaft 41 protruding from the first case half 45 to the left side, and an inner stator 63 surrounded by the outer rotor 62 and disposed around the crankshaft 41. The left end portion of the inner stator 63 is fixed to the left side cover 47L. An electromagnetic coil is wound around the inner stator 63, and magnets of N poles and S poles are alternately fixed to the outer rotor 62. When the outer rotor 62 rotates relative to the inner stator 63, electric power is induced in the electromagnetic coil. The outer rotor 62 is also referred to as a flywheel.

[0017] A primary drive gear 70a is provided at the end of the crankshaft 41 opposite to the generator 61 (right end), which rotates integrally with the crankshaft 41. A primary driven gear 70b is provided on the main shaft 42 so as to be able to rotate relative to the primary drive gear 70a. A multi-plate clutch device 71 is provided on the main shaft 42, on the outside (right side) of the crankcase 31, with the primary driven gear 70b in between, to disconnect and reconnect power transmission between the crankshaft 41 and the main shaft 42. The multi-plate clutch device 71 (hereinafter referred to as clutch device 71) is an auxiliary device coaxially connected to the main shaft 42 and is housed in the clutch chamber Rc.

[0018] Figure 3 shows the clutch device 71. As shown in Figure 3, the clutch device 71 includes a clutch outer 72 that is rotatably supported relative to the main shaft 42, and a clutch center 73 that rotates integrally with the main shaft 42 on the inner circumference of the clutch outer 72. A primary driven gear 70b is connected to the clutch outer 72. Therefore, the rotation of the crankshaft 41 is transmitted to the clutch outer 72 via a primary reduction mechanism consisting of a primary drive gear 70a and a primary driven gear 70b.

[0019] The clutch device 71 is supported by the clutch outer 72 and the clutch center 73 in the axial direction of the main shaft 42, and includes friction members 74 that exert frictional force when in contact with each other and transmit rotational force from the clutch outer 72 to the clutch center 73.

[0020] The friction member 74 includes a plurality of clutch discs 75 spline-coupled to one of the clutch outer 72 and clutch center 73 in a manner that prevents relative rotation, and a plurality of clutch plates 76 arranged alternately with the clutch discs 75 and spline-coupled to the other of the clutch outer 72 and clutch center 73 in a manner that prevents relative rotation. When the clutch discs 75 and clutch plates 76 are in contact (also called mutual contact), rotational force is transmitted from the primary drive gear 70a to the clutch center 73 via the clutch outer 72. When the clutch discs 75 and clutch plates 76 are released from contact, slippage occurs between them, and the transmission of rotational force is interrupted.

[0021] The clutch center 73 supports a pressure plate 78 that is movable in the axial direction of the main shaft 42 between a restrained position that maintains the pressure-contact state of the clutch disc 75 and clutch plate 76 under the biasing force of the biasing member 77, and an open position that releases the clutch disc 75 and clutch plate 76 from the pressure-contact state against the biasing force of the biasing member 77. The clutch device 71 is formed as a normally closed clutch that is normally engaged when there is no external input.

[0022] The clutch release mechanism 81, located near the inside of the left-side cover 47L, releases the pressure contact between the clutch disc 75 and the clutch plate 76. The clutch release mechanism 81 releases the pressure contact between the clutch disc 75 and the clutch plate 76 in response to clutch operation (manual operation) by the occupant. The clutch release mechanism 81 has a clutch lifter rod 82 located within the main shaft 42, which moves the pressure plate 78 to the open position via the clutch lifter rod 82 in response to clutch operation, releasing the pressure contact between the clutch disc 75 and the clutch plate 76. When the pressure contact is released, the clutch center 73 spins freely, and power transmission to the main shaft 42 is interrupted.

[0023] The gear group 85 provided on the main shaft 42, the counter shaft 43, and both shafts 42 and 43 constitute a stepped transmission 86. The transmission 86 is housed in a gear chamber Rd located behind the crankshaft 41 and inside the clutch chamber Rc in the vehicle width direction within the first case half 45 and the second case half 46. The rotational force transmitted from the crankshaft 41 to the main shaft 42 is transmitted to the countershaft 43 via the transmission 86. The countershaft 43 is the output shaft of the transmission 86 and also serves as the output shaft of the engine 12. The left end of the countershaft 43 protrudes from the rear left side of the crankcase 31, and the drive sprocket 87 is attached to this protruding portion.

[0024] Let's explain the clutch device 71 further. Figure 4 shows the clutch disc 75 and clutch plate 76. Figure 4 and the figures described later show the rotation direction Rdc when the engine is running. The clutch disc 75 is a flat, annular plate made of aluminum alloy, and an engaging portion 75k that fits into the clutch center 73 is provided on its inner circumference. The clutch disc may be made of a material with a lower specific gravity than iron, such as carbon. The engaging portions 75k are arranged at predetermined angular intervals with respect to the center Cd of the clutch disc 75. The center Cd of the clutch disc 75 coincides with the center C2 of the main shaft 42 and the center Cp of the clutch plate 76.

[0025] Grooves 73m (Figure 3) extending in the axial direction of the main shaft 42 are formed on the outer circumference of the clutch center 73 at circumferential intervals, and the engaging portion 75k of the clutch disc 75 engages with each groove 73m. As a result, the clutch disc 75 is mounted on the clutch center 73 so that it is movable in the axial direction of the main shaft 42, but not movable in the circumferential direction of the main shaft 42.

[0026] Ring-shaped friction material 75f is arranged on both sides of the clutch disc 75. The ring-shaped friction material 75f is continuously provided along the circumferential direction of the clutch plate 76 in the region facing the clutch plate 76. Note that the ring-shaped friction material 75f is not limited to a completely endless ring shape; it may also be a configuration in which friction material with both ends is arranged in a ring shape, or a configuration in which there is a gap between the ends and it is arranged in a substantially ring shape (for example, C-shape). By arranging the ring-shaped friction material 75f, the surface area of ​​the friction material 75f can be secured, reducing wear of the friction material 75f and making it easier to extend its lifespan.

[0027] Furthermore, the friction material 75f is not limited to a ring shape; for example, as shown in Figure 5, segmented friction material 75f arranged at intervals in the circumferential direction of the clutch disc 75 may be used. By using segmented friction material 75f, the arrangement position and quantity of the friction material 75f can be flexibly adjusted.

[0028] As shown in Figure 4, the clutch plate 76 is a flat, annular plate made of an iron-based material, and an engaging portion 75k that engages with the clutch outer 72 is provided on its outer circumference. The engaging portions 75k are arranged at predetermined angular intervals with respect to the center Cp of the clutch plate 76 (which coincides with the center C2 of the main shaft 42 and the center Cd of the clutch disc 75). Grooves 72m (Figure 3) extending in the axial direction of the main shaft 42 are formed on the inner circumference of the clutch outer 72 at circumferential intervals, and the engaging portion 75k of the clutch plate 76 engages with each groove 72m. As a result, the clutch plate 76 is mounted on the clutch outer 72 so that it is movable in the axial direction of the main shaft 42, but not movable in the circumferential direction of the main shaft 42.

[0029] Oil drain grooves 73m are formed on both sides of the clutch plate 76. The oil drain grooves 73m are formed as grooves that extend in the centrifugal direction and can be called centrifugal grooves or radial grooves. Figure 6 shows the clutch plate 76 from multiple angles. Figure 7 shows the clutch plate 76 together with the crankcase 31 from the side of the vehicle body. As shown in Figure 6, in a side cross-sectional view of the clutch plate 76, the engaging portion 76k extends linearly from the clutch plate 76. The oil discharge groove 73m is formed on both sides of the clutch plate 76, that is, on both the outer surface in the vehicle width direction and the inner surface in the vehicle width direction, as a groove inclined at a predetermined angle from the exact centrifugal direction of the clutch plate 76.

[0030] The oil drain groove 73m can be described as a groove that slopes backward (opposite to the direction of rotation) relative to the rotation direction Rdc of the clutch plate 76. Alternatively, the oil drain groove 73m can be described as a groove that slopes backward (opposite to the direction of rotation) relative to the line Lk that extends radially from the center Cp of the clutch plate 76.

[0031] Figure 7 shows the upper level (oil level) Lm of the oil stored in the lower part of the crankcase 31 (including the lower part of the clutch chamber Rc). The oil is a liquid used for lubrication and cooling of various parts of the engine 12, and can be called engine oil, motor oil, or lubricating oil. As shown in Figure 7, the clutch device 71 in this configuration is a wet clutch device in which a portion is immersed in oil. Therefore, when oil enters between the clutch disc 75 and the clutch plate 76 as each component of the clutch device 71 rotates, the entered oil is discharged by the oil discharge groove 73.

[0032] According to the inventors' studies, by making the oil discharge groove 73m between the clutch disc 75 and the clutch plate 76 a groove that is inclined to the rear in the direction of rotation as described above, it has been confirmed that the oil that enters between the clutch disc 75 and the clutch plate 76 is pushed outward by centrifugal force and at the same time efficiently discharged along the oil discharge groove 73m by kinetic energy in the direction of rotation Rdc. This reduces clutch drag and is advantageous in improving the maneuverability of off-road vehicles. Furthermore, by providing such an oil discharge groove 73m, the flow of oil is controlled, the cooling effect of the clutch device 7 and its surroundings is enhanced, and a lubricating effect is obtained to lubricate the friction material 75f. In addition, it is expected to have the effect of discharging wear particles generated during clutch use.

[0033] Figure 8 shows the clutch plate 76 together with the clutch center 73 and pressure plate 78. As shown in Figure 8, in this configuration, one end of the clutch plate 76 in the stacking direction (corresponding to the left end) is in contact with the clutch center 73, and the other end of the clutch plate 76 in the stacking direction (right end) is in contact with the pressure plate 78. On the clutch plate 76, the surfaces in contact with the clutch center 73 and the pressure plate 78 do not have oil discharge grooves 73m, and friction material 76f is provided on each. These friction materials 76f ensure that the friction force between the friction member 74, including the clutch disc 75 and the clutch plate 76, and the clutch center 73 and the pressure plate 78 is appropriately secured.

[0034] For the friction material 76f, any appropriate friction material should be used within a range that ensures adequate frictional force. For example, by using a ring-shaped friction material 76f, the surface area of ​​the friction material 76f can be increased, thereby extending its lifespan. Alternatively, by using a segment-shaped friction material 76f, the placement and quantity of the friction material 75f can be flexibly adjusted, and oil discharge can also be promoted.

[0035] As described above, the clutch device 71 of this embodiment is configured such that the clutch plate 76, which is relatively heavier than the clutch disc 75 made of aluminum alloy and the clutch plate 76 made of iron-based material, engages with the clutch outer 72 which rotates together with the crankshaft 41, and one end of the clutch plate 76 in the stacking direction contacts the clutch center 73, while the other end of the clutch plate 76 in the stacking direction contacts the pressure plate 78.

[0036] This configuration allows the inertia of the clutch plate 76 to be utilized when the clutch is disengaged, thereby enabling a reduction in the weight of the crankshaft, which is the weight on the crank side. Furthermore, compared to the conventional structure in which the relatively lightweight clutch disc 75 engages with the clutch outer 72, the change in inertia or mass before and after clutch engagement is reduced, allowing for a smoother rise in rotation after clutch engagement. Therefore, a clutch device 71 can be realized that enables a reduction in crank weight and suppresses the impact on the rotational start-up after clutch engagement. This contributes to improved maneuverability and weight reduction of the saddle-type vehicle 10.

[0037] Furthermore, a friction material 76f is provided on the surface of the clutch plate 76 that contacts the clutch center 73 and the pressure plate 78. With this configuration, the contact points with the clutch center 73 and the pressure plate 78 can be made to be in contact via the friction material. Therefore, a good feel can be provided even if the engagement points of the clutch disc 75 and the clutch plate 76 are reversed.

[0038] Furthermore, ring-shaped friction material 75f is provided on both sides of the clutch disc 75, and oil discharge grooves 73m, which are centrifugal grooves, are provided on both sides of the clutch plate 76 that contacts the clutch disc 75. This configuration allows for a larger surface area of ​​the friction material, thereby extending the lifespan of the friction material. In addition, the centrifugal oil discharge grooves 73m allow for the discharge of oil or other fluids that may enter between the clutch disc 75 and the clutch plate 76.

[0039] Furthermore, since the oil discharge groove 73m is a groove that is inclined toward the rear in the rotational direction with respect to the line Lk that extends radially from the center Cp of the clutch plate 76, it can more effectively discharge oil that has entered between the clutch disc 75 and the clutch plate 76, thereby reducing clutch drag.

[0040] Furthermore, the engine 12 in this configuration employs a wet lubrication system, and a portion of the clutch device 71 is positioned immersed in oil. This improves the lubrication of the clutch device 71 and its surroundings.

[0041] [Other embodiments] The above embodiments represent only one aspect of the present invention and can be modified and applied as needed without departing from the spirit of the invention.

[0042] For example, in the above embodiment, the present invention was described in the case of applying it to the clutch device 71 of the saddle-type vehicle 10 shown in Figure 1. However, the present invention may also be applied to the clutch device of any saddle-type vehicle, the clutch device of a moving body other than a saddle-type vehicle, and the clutch device not for use with a moving body. Furthermore, although the present invention was described in the case of applying it to a wet clutch device 71, it is not limited to this and may also be applied to a dry clutch device.

[0043] [Configurations supported by the above embodiment] The above embodiment supports the following configuration.

[0044] (Configuration 1) A multi-plate clutch device comprising a clutch outer that transmits the rotation of a crankshaft, a clutch center that rotates integrally with the main shaft, a clutch disc made of an aluminum alloy, and clutch plates made of an iron-based material stacked alternately, and a pressure plate biased by a biasing member to generate frictional force between the clutch disc and the clutch plates, wherein the clutch disc is provided with an engaging portion that engages with the clutch center, the clutch plate is provided with an engaging portion that engages with the clutch outer, the clutch plate at one end in the stacking direction is in contact with the clutch center, and the clutch plate at the other end in the stacking direction is in contact with the pressure plate. This configuration allows the inertia of the clutch plates, which are made of iron-based material, to be utilized when the clutch is disengaged. This enables a reduction in crank weight and minimizes the change in inertia or mass before and after clutch engagement. Therefore, it is possible to reduce the crank weight and minimize the impact on the rotational start-up after clutch engagement.

[0045] (Configuration 2) The multi-plate clutch device according to Configuration 1, wherein friction material is provided on the surface of the clutch plate that contacts the clutch center and the pressure plate. This configuration allows the contact points with the clutch center and pressure plate to be in contact via friction material, and provides a good feel even if the engagement points of the clutch disc and clutch plate are reversed.

[0046] (Configuration 3) A multi-plate clutch device according to Configuration 1 or 2, wherein ring-shaped friction material is provided on both sides of the clutch disc, and grooves extending in the centrifugal direction are provided on both sides of the clutch plate that contacts the clutch disc. This configuration allows for a larger surface area for the friction material, making it easier to extend its lifespan. Furthermore, the centrifugal grooves allow for the discharge of any oil or other fluids that may enter the space between the clutch disc and clutch plate.

[0047] (Configuration 4) The multi-plate clutch device according to Configuration 3, wherein the groove is an oil discharge groove that is inclined backward in the rotational direction with respect to a line extending radially from the center of the clutch plate. This configuration allows for more effective drainage of oil that has entered between the clutch disc and clutch plate, thereby reducing clutch drag.

[0048] (Configuration 5) A multi-plate clutch device according to any one of Configurations 1 to 4, wherein a part of the multi-plate clutch device is arranged in a state of being immersed in oil. This configuration improves the lubrication of the multi-plate clutch device and its surroundings. [Explanation of Symbols]

[0049] 10. Saddle-type vehicles 11. Body frame 12 Engines 31 Crankcase 41 Crank axle 42 Main axis 71 Multi-plate clutch device 72 Clutch Outer 73 Clutch Center 73m oil drain channel 75 Clutch Disc 75k,76k Engagement part 75f,76f Friction material 76 Clutch Plates 77 Biasing member 78 Pressure Plate

Claims

1. The clutch outer (72) transmits the rotation of the crankshaft (41), A clutch center (73) that rotates integrally with the main shaft (42), In a multi-plate clutch device having a clutch disc (75) made of aluminum alloy and a clutch plate (76) made of iron-based material stacked alternately, and a pressure plate (78) biased by a biasing member (77) to generate frictional force between the clutch disc (75) and the clutch plate (76), The clutch disc (75) is provided with an engaging portion (75k) that engages with the clutch center (73), The clutch plate (76) is provided with an engaging portion (76k) that engages with the clutch outer (72), with one end of the clutch plate (76) in the stacking direction in contact with the clutch center (73), and the other end of the clutch plate (76) in the stacking direction in contact with the pressure plate (78). Multi-plate clutch device.

2. A friction material (76f) is provided on the surface of the clutch plate (76) that contacts the clutch center (73) and the pressure plate (78). The multi-plate clutch device according to claim 1.

3. Ring-shaped friction material (75f) is provided on both sides of the clutch disc (75). Grooves (73m) extending in the centrifugal direction are provided on both sides of the clutch plate (76) that is in contact with the clutch disc (75). The multi-plate clutch device according to claim 1.

4. The groove (73m) is an oil discharge groove that is inclined backward in the rotational direction with respect to a line (Lk) extending radially from the center of the clutch plate (76). The multi-plate clutch device according to claim 3.

5. A portion of the multi-plate clutch device (71) is positioned immersed in oil. A multi-plate clutch device according to any one of claims 1 to 4.

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