JPH04316724A - Multiple disc centrifugal clutch - Google Patents

Abstract

PURPOSE:To prevent a disc from growing in a large size in the case of incorporating a back torque limiter in a multiple disc centrifugal clutch. CONSTITUTION:A clutch drum 2 is provided so that it can freely move axially with respect to a pressurizing plate 10, and driving clutch discs 8 are arranged between the clutch drum 2 and the pressurizing plate 10. A moving plate 21 is connected with the pressurizing plate through centrifugal balls 20, and the moving plate 21 is elastically supported on the clutch drum 2 through clutch torque limiter springs 27. Further, cam faces 10b, 21b are provided at the respective engaging parts of the pressurizing plate 10 and the moving plate 21 with the centrifugal balls. Without installing any additional member, a back torque limiter can be composed of main components of the clutch, namely the pressurizing plate 10, the centrifugal balls 20, the moving plate 21, etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-disc centrifugal clutch using centrifugal balls.

0002

2. Description of the Related Art Conventionally, multi-disc centrifugal clutches using centrifugal balls have been mainly used in small motorcycles such as scooters and business bikes. This multi-disc centrifugal clutch has a centrifugal ball installed on the inner periphery of a clutch drum driven by the engine so that it moves toward the clutch plate as the clutch drum rotates, and a pressure plate that is biased by a clutch spring. The clutch plate is compressed by the centrifugal ball and the centrifugal ball. That is, in the conventional multi-disc centrifugal clutch, the clutch is disengaged when the engine is idling, but as the engine speeds up, the centrifugal ball moves toward the clutch plate and the clutch becomes engaged.

By the way, in a shaft drive type motorcycle equipped with a four-cycle engine, a back torque limiter is sometimes attached to the clutch in order to prevent the rear wheel from slipping due to engine braking the moment the accelerator is released. This back torque limiter is usually constructed by interposing a roller type or sprag type one-way clutch between a clutch hub and a clutch plate.

0004

SUMMARY OF THE INVENTION The inventor is considering incorporating a back torque limiter into a conventional multi-disc centrifugal clutch. However, simply incorporating the above-mentioned one-way clutch into a conventional multi-disc centrifugal clutch causes the problem that the clutch, which was originally compactly designed for use in small motorcycles, ends up becoming larger. Moreover, the number of parts increases, leading to an increase in cost.

[0005]

[Means for Solving the Problems] A multi-disc centrifugal clutch according to the present invention has a clutch plate disposed between the inner bottom surface of the clutch drum and the pressure plate, so that the clutch drum can be freely moved in the axial direction with respect to the pressure plate. At the same time, a pressure plate is connected to the clutch drum with a constant rotation width, and a pressure plate is provided on the opposite side of the pressure plate from the clutch plate, and is elastically supported by the clutch drum via a clutch spring and connected to the clutch drum. A movable plate whose relative rotation is regulated is connected via a centrifugal ball, and the centrifugal ball engaging portion of the pressure plate has a
A cam surface is formed that gradually protrudes toward the movable plate as it moves forward in the rotational direction, and a cam surface that gradually protrudes toward the pressure plate as it moves rearward in the rotational direction is formed on the centrifugal ball engaging portion of the movable plate. It is something.

[0006]

[Operation] When the clutch is engaged and power is being transmitted, the position of the pressure plate shifts toward the rear in the rotation direction with respect to the clutch drum, so the centrifugal ball rolls up the cam surface and the movable plate moves from the pressure plate. Separate. When back torque is applied to the clutch plate in this state, the pressure plate shifts forward in the rotational direction relative to the clutch drum, the centrifugal ball rolls down the cam surface, and the movable plate approaches the pressure plate, causing the clutch spring to rebound. The power will be weakened and the clutch plate will become slippery.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3. FIG. 1 is a sectional view of a multi-disc centrifugal clutch according to the present invention, FIG. 2 is a front view of a clutch drum of the multi-disc centrifugal clutch according to the present invention, and FIG. 3 is an enlarged view of the main parts of the multi-disc centrifugal clutch according to the present invention. FIG. In these figures, 1 is a multi-disc centrifugal clutch mounted on a motorcycle engine, 2 is an input clutch drum of the multi-disc centrifugal clutch 1, and 3 is an output shaft. The clutch drum 1 is generally formed into a cylindrical shape with a bottom, and is supported by the output shaft 3 via a sliding bearing so as to be freely rotatable and movable in the axial direction. 4 indicates a metal bush for a sliding bearing that supports this clutch drum 2. Further, a gear 5 connected to a crankshaft (not shown) of an engine is fixed to the boss portion of the clutch drum 2. Further, in the cylindrical portion of the clutch drum 2, guide grooves 2a, in which a clutch plate, a pressure plate, a moving plate, etc. to be described later are engaged, are arranged in parallel at equal intervals in the circumferential direction. Note that the output shaft 2 is connected to a transmission (not shown). In this embodiment, the clutch drum 2 and the output shaft 3 are configured to rotate in the direction shown by arrow A in FIG. 1 when the engine is operated. In the following, the direction of arrow A will be referred to as the forward direction of rotation. 6 is a drive plate which engages with the guide groove 2a of the clutch drum 2 and rotates together with the clutch drum 2; 7 is a clutch plate 8 together with the drive plate 6;
This driven plate 7 is connected to a clutch hub 9 provided at the shaft end of the output shaft 3. A plurality of drive plates 6 and driven plates 7 are alternately mounted in the axial direction, and are positioned at the bottom side of the clutch drum 2.

Reference numeral 10 denotes a pressure plate on which the clutch plate 8 approaches and separates.
It consists of a disc part 11 whose outer periphery engages with a and is formed with a friction surface that comes into contact with the clutch plate 8, and a cylindrical shaft part 12 fixed to the axial center of this disc part 11. Shaft part 12
is rotatably supported with respect to the engine crankcase 13 with movement in the axial direction restricted. Note that 14 and 15 indicate bearings that support the shaft portion 12 on the crankcase 13, and 16 indicates a bearing that rotatably connects the disc side end of the shaft portion 12 to the shaft end of the output shaft 3. Furthermore, the engaging portion 11a of the disc portion 11 that engages with the guide groove 2a is formed to be narrower than the guide groove 2a, as shown in FIG. That is, by doing so, the pressure plate 10 is rotatably connected to the clutch drum 2 with a fixed rotation width.

20 is a centrifugal ball, and 21 is a moving plate connected to the pressure plate 10 via the centrifugal ball 20. The movable plate 21 is elastically supported by the pressure plate 10 via a support pin 22 and a clutch-in spring 23 erected on the pressure plate 10, and applies the centrifugal ball 20 by the elastic force of the clutch-in spring 23. It is configured to be brought into pressure contact with the pressure plate 10. In addition, this moving plate 2
An engaging portion 21a that fits into the guide groove 2a of the clutch drum 2 is provided on the outer peripheral portion of the clutch drum 2. By fitting the engaging portion 21a into the guide groove 2a in this way, the movable plate 21
is prevented from rotating relative to the clutch drum 2. The centrifugal ball 20 is connected to the clutch drum engaging portion 1 of each of the pressure plate 10 and the moving plate 21.
They are sandwiched between 0a and 21a and held between them so as to be able to freely roll in the radial direction of the pressure plate 10, and a plurality of them are arranged in parallel at predetermined intervals in the circumferential direction of the pressure plate 10. The portion of the engaging portion 10a of the pressure plate 10 that contacts the centrifugal ball 20 is a groove that is inclined so as to gradually approach the movable plate as it goes radially outward. The side wall of the groove is formed by a cam surface 1 that gradually protrudes toward the moving plate 21 as it goes forward and backward in the rotational direction, as shown in FIG.
It constitutes 0b. Furthermore, the engaging portion 21a of the moving plate 21
is curved to form a ball rolling groove that extends in the radial direction, and the inner circumferential wall surface of the curved portion gradually protrudes toward the pressure plate 10 as it goes forward and backward in the rotational direction. It constitutes a cam surface 21b. If the structure is such that the centrifugal ball 20 is held under pressure by both the engaging parts 10a and 21a, the centrifugal ball 20 moves radially outward as the rotational speed increases, and the centrifugal ball 20 moves the movable plate 21 to the pressure plate. 10. The moving direction of the moving plate 21 at this time is indicated by arrow B in FIG. Further, when the rotational speed decreases, the movable plate 21 and the centrifugal ball 20 are returned to their original positions by the elastic force of the clutch-in spring 23.

Reference numeral 24 denotes an end plate screwed to the open end of the clutch drum 2.
4, the movable plate 21 is connected to the movable plate 21 via a guide 25 and a guide pin 26 fixed to the guide 25 so as to be movable in the axial direction. 27 is a clutch torque limiter spring that biases the movable plate 21 in a direction away from the end plate 24 and constitutes a clutch spring;
This clutch torque limiter spring 27 is elastically mounted between the end plate 24 and the movable plate 21. The clutch torque limiter spring 27 has a spring constant larger than that of the clutch in-spring 23 that is elastically mounted between the pressure plate 10 and the movable plate 21, and is spaced apart in the circumferential direction as shown in FIG. Three clutch-in springs 23 are arranged in parallel between the three clutch-in springs 23 arranged in the same direction. In this way, both springs 23, 27
By changing the spring constants, when the centrifugal ball 20 starts moving and the movable plate 21 separates from the pressure plate 10, the clutch-in spring 23 is first compressed. That is, at the beginning of the movement of the movable plate 21, the movable plate 21, the end plate 24, and the clutch drum 2 move in the direction of arrow B without changing the distance between the movable plate 21 and the end plate 24. Then, when the rotational speed increases and the clutch plate 8 comes to be pressed between the bottom of the clutch drum 2 and the pressure plate 10, the clutch torque limiter spring 27 comes to be compressed. The clutch plate 8 is compressed by the elastic force of the clutch torque limiter spring 27, and the clutch is connected.

Reference numeral 31 denotes a clutch release mechanism, and this clutch release mechanism 31 moves a push rod 32, which is fitted into the shaft portion 13 of the pressure plate 10 so that it can move forward and backward, downward in FIG.
(to the opposite side), the clutch drum 2 is moved in the same direction, and the clutch is forcibly released. The base end of the push rod 32 engages with an operating cam 33 having a semicircular cross section, and a pin 34 for pushing the end plate 24 is fixed to the pushing end. This pin 34 passes through the opening 12a that communicates the inside and outside of the shaft portion 13 and faces into the circular recess 24a of the end plate 24. Further, the operating cam 33 is rotatably provided with respect to the crankcase 13,
It is configured to rotate and press the push rod 32 by operating a clutch lever (not shown). According to this clutch release mechanism 31, when the operating cam 33 pushes the push rod 32, the pin 34 pushes the end plate 24.
4, the clutch drum 2 moves in the direction opposite to the arrow B, and the clutch is disengaged. At this time, if the engine is rotating at high speed and the movable plate 21 does not return to the pressure plate 10 side, the clutch torque limiter spring 27 will be compressed and the end plate 24 will shift toward the movable plate 21 side. Become.

Next, the operation of the multi-disc centrifugal clutch according to the present invention constructed as described above will be explained. When the engine is in an idling state, as shown in FIG. 1, the centrifugal ball 20 is held on the radial center side of the clutch drum 2 by the movable plate 21 urged by the clutch inspring 23. At this time, since the moving plate 21 is close to the pressure plate 10, the rotation of the clutch drum 2 is not transmitted to the output shaft 3. Then, when the engine speed is increased,
The centrifugal ball 20 moves radially outward due to centrifugal force,
The moving plate 21 becomes separated from the pressure plate 10. When the rotation further increases, the clutch plate 8 is compressed between the pressure plate 10 and the bottom of the clutch drum 2, and power is transmitted from the clutch drum 2 to the output shaft 3. On the other hand, when the clutch lever is operated with the clutch engaged, the push rod 32 of the clutch release mechanism 31 moves downward in FIG. 1, moves the clutch drum 2 in the same direction, and releases the clutch.

Furthermore, when the clutch is engaged and power is transmitted, the pressure plate 10 becomes difficult to rotate due to frictional force with the clutch plate 8, and rotates rearward relative to the clutch drum 2. Then, the engaging portion 10a is displaced rearward in the rotational direction within the guide groove 2a of the clutch drum 2. This state is shown by the two-dot chain line in FIG. At this time, the centrifugal ball 20 slightly rolls in the circumferential direction between the engaging portion 10a of the pressure plate 10 and the engaging portion 21a of the moving plate 21, and
The front cam surface 10b of the movable plate 21 and the rear cam surface 21b of the engaging portion 21a of the movable plate 21 come to be pressed. In other words, the centrifugal ball 20 has cam surfaces 10b and 21b.
It will roll up. Here, since the pressure plate 10 is restricted from moving in the axial direction, the movable plate 21 is separated from the pressure plate 10 by the dimension indicated by l in FIG. 3, and the clutch torque limiter spring 27 is compressed by that amount. That will happen. That is, in this multi-disc centrifugal clutch, the centrifugal ball 20 moves radially outward due to centrifugal force;
Both the centrifugal ball 20 rolling up the cam surfaces 10b and 21b push the movable plate 21 and engage the clutch. When the clutch is engaged and back torque is applied from the rear wheels due to engine braking, for example, the power of the clutch plate 8, which attempts to rotate in the opposite direction relative to the clutch drum 2, is transferred to the movable plate 10. As a result, the movable plate 10 is displaced forward in the rotational direction with respect to the clutch drum 2. In this way, moving plate 1
0 moves, the centrifugal ball 20 moves onto the cam surfaces 10b, 21
Since the movable plate 21 approaches the pressure plate 10 by rolling down the clutch torque limiter spring 27
The elastic force of the clutch plate 8 becomes weaker and the clutch plate 8 becomes more slippery. Therefore, in the multi-plate centrifugal clutch 1 configured as described above, a back torque limiter is configured by the pressure plate 10, the centrifugal ball 20, the movable plate 21, etc. as the main components of the clutch.

In this embodiment, the cam surfaces 10b and 21b are provided before and after the rotation direction of the pressure plate 10 and the movable plate 21, but the cam surfaces are as shown in FIGS. 4(a) and 4(b). It can also be formed into FIG. 4 is a sectional view showing another embodiment of the cam surface, in which FIG. 4(a) shows the state before the clutch is engaged, and FIG. 4(b) shows the state after the clutch is engaged. Figure 4 (
In a) and (b), the same or equivalent members as those explained in FIGS. 1 to 3 are given the same reference numerals and detailed explanations will be omitted. In FIGS. 4A and 4B, the cam surface 10b of the pressure plate 10 is formed only on the front side in the rotation direction, and the cam surface 21b of the moving plate 21 is formed only on the rear side in the rotation direction. Even with this configuration, effects similar to those of the above embodiment can be obtained.

[0015]

As explained above, the multi-disc centrifugal clutch according to the present invention has a clutch plate disposed between the inner bottom surface of the clutch drum and the pressure plate, and moves the clutch drum in the axial direction with respect to the pressure plate. A pressurizing plate is connected to the clutch drum with a certain rotation width, and a pressurizing plate is provided on the opposite side of the pressurizing plate from the clutch plate and is elastically supported by the clutch drum via a clutch spring and connected to the clutch drum. A movable plate whose relative rotation is regulated is connected via a centrifugal ball, and a cam surface that gradually protrudes toward the movable plate as it moves forward in the rotational direction is formed on the centrifugal ball engaging portion of the pressurizing plate. In addition, a cam surface is formed on the centrifugal ball engaging portion of the movable plate that gradually protrudes toward the pressure plate as it goes rearward in the rotational direction, so when the clutch is engaged and power is being transmitted, the position of the pressure plate is shifts toward the rear in the rotational direction with respect to the clutch drum,
The centrifugal ball rolls up the cam surface and the movable plate is separated from the pressure plate. When back torque is applied to the clutch plate in this state, the pressure plate shifts forward in the rotational direction relative to the clutch drum, the centrifugal ball rolls down the cam surface, and the movable plate approaches the pressure plate, causing the clutch spring to rebound. The power will be weakened and the clutch plate will become slippery. Therefore, since the back torque limiter is constituted by the pressure plate, centrifugal ball, moving plate, etc. as the main components of the clutch, a multi-disc centrifugal clutch with a back torque limiter can be obtained without adding any special members. Therefore, a back torque limiter can be built into the multi-disc centrifugal clutch without increasing the size of the device. In addition, in the multi-disc centrifugal clutch according to the present invention, the movable plate is moved by both the movement of the centrifugal ball radially outward by centrifugal force and the movement of the centrifugal ball by rolling up the cam surfaces of the pressure plate and the movable plate. Since the clutch is engaged when it is pushed, it has the effect of improving responsiveness when the clutch is engaged, compared to conventional centrifugal clutches that rely only on centrifugal force to move the movable plate.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a multi-disc centrifugal clutch according to the present invention.

FIG. 2 is a front view of a clutch drum of the multi-disc centrifugal clutch according to the present invention.

FIG. 3 is a plan view showing an enlarged main part of the multi-disc centrifugal clutch according to the present invention.

FIG. 4 is a cross-sectional view showing another example of the cam surface;
) shows the state before the clutch is engaged, and (b) of the same figure shows the state after the clutch is engaged.

[Explanation of symbols]

1 Multi-disc centrifugal clutch 2 Clutch drum 8 Clutch plate 10 Pressure plate 10a Engagement part 10b Cam surface 20 Centrifugal ball 21　　　　　Moving board 21a Engagement part 21b Cam surface 23 Clutch in spring

Claims (1)

[Claims] 1. A multi-plate centrifugal clutch in which a moving plate is moved in the axial direction within an input clutch drum by a centrifugal ball, and the movement of the moving plate brings the clutch plate and the pressure plate into contact with and away from each other. A clutch plate is disposed between the bottom surface and the pressure plate, the clutch drum is provided to be movable in the axial direction with respect to the pressure plate, and the pressure plate is connected to the clutch drum with a constant rotation width, A movable plate that is elastically supported by the clutch drum via a clutch spring and whose relative rotation with the clutch drum is regulated is connected to the pressure plate on the opposite side of the clutch plate via a centrifugal ball, and the pressure plate A cam surface is formed on the centrifugal ball engaging portion of the movable plate that gradually protrudes toward the movable plate as it goes forward in the rotational direction, and a cam surface that gradually protrudes toward the pressure plate as it goes rearward in the rotational direction is formed on the centrifugal ball engaging portion of the movable plate. A multi-disc centrifugal clutch characterized by a cam surface that protrudes from the top.