Centrifugal clutch and method of reproducing or changing clutch characteristic in centrifugal clutch

Abstract

To provide a centrifugal clutch capable of simplifying exchange operation of an assist cam body or assembly operation of the centrifugal clutch, and a method of reproducing or changing clutch characteristics in the centrifugal clutch.SOLUTION: A centrifugal clutch 200 is provided with a clutch weight 240 and an assist cam body 220 on a drive plate 210 rotary driven by a driving force of an engine. In the clutch weight 240, a weight side driven part 245 which rotates and is displaced to a clutch outer 250 side and rides over the assist cam body 220 is formed. The assist cam body 220 is formed into an almost square in a planar view, and has a first cam surface 221, a second cam surface 222, a third cam surface 223, and a fourth cam surface 224 selectively sliding in a weight side driven part 245 on four side surfaces. The assist cam body 220 is formed at a location where a mounting hole 225 is eccentric on a cross-section surface in the assist cam body.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] This invention relates to a centrifugal clutch that blocks the transmission of rotational driving force to the driven side until the engine reaches a predetermined rotational speed, and transmits the rotational driving force to the driven side when the engine reaches the predetermined rotational speed. [Background technology]

[0002] Conventionally, centrifugal clutches that transmit rotational driving force to a driven side when an engine reaches a predetermined rotation speed have been used in motorcycles, brush cutters, and the like. For example, the following Patent Document 1 discloses a centrifugal clutch that includes a drive plate that is rotationally driven by the rotational driving force from the engine, and a clutch weight that is rotatably supported by the drive plate and opens radially outward by the rotational drive of the drive plate and is pressed against the clutch outer. In this case, the centrifugal clutch includes a protrusion (hereinafter referred to as an "assist cam body") and a driven part that form a pair of cams between the drive plate and the clutch weight, and is configured so that the pair of cams can quickly and strongly press the clutch weight against the clutch outer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-9675 A

[0004] However, the centrifugal clutch described in Patent Document 1 has a problem in that the preparation of the assist cam body, which is configured in a roller shape, is complicated when replacing the assist cam body or when assembling the centrifugal clutch.

[0005] For example, in a conventional centrifugal clutch, when the assist cam body needs to be replaced due to wear or damage, a new assist cam body must be prepared, and when it is desired to change the clutch characteristics of the centrifugal clutch by changing the cam characteristics of the assist cam body and the driven part, a new assist cam body that exerts the desired cam characteristics must be prepared separately. Also, in the process of assembling multiple types of centrifugal clutches with different cam characteristics (clutch characteristics), an assist cam body must be prepared for each desired cam characteristic.

[0006] The present invention has been made to address the above problems, and its object is to provide a centrifugal clutch and a method for restoring or changing the clutch characteristics of a centrifugal clutch that can simplify the replacement work of an assist cam body or the assembly work of a centrifugal clutch. Summary of the Invention

[0007] In order to achieve the above-mentioned object, the present invention is characterized in that it comprises a drive plate that is rotated by receiving a driving force from a driving source, a plurality of clutch weights that are displaced so as to contact or move away from the cylindrical surface of the clutch outer by the centrifugal force caused by the rotation of the drive plate, an assist cam body that has a cam surface and is rotatably mounted on the drive plate, and a weight-side follower part that is mounted on the clutch weight and is pressed by the cam surface of the assist cam body when the clutch weight is displaced, and the assist cam body has a plurality of cam surfaces formed thereon, and one of these plurality of cam surfaces presses the weight-side follower part.

[0008] According to this, since the centrifugal clutch has multiple cam surfaces formed on the assist cam body, the desired cam characteristics can be obtained by attaching the desired cam surface to the drive plate so as to face the weight-side driven part, and the work of replacing the assist cam body or the work of assembling the centrifugal clutch can be simplified. In this case, the centrifugal clutch can maintain the cam characteristics or regenerate changed cam characteristics by forming the multiple cam surfaces constituting the assist cam body in the same shape, and can change the cam characteristics by forming the multiple cam surfaces in different shapes.

[0009] Another feature of the present invention is that in the centrifugal clutch, the assist cam body has at least one of the multiple cam surfaces formed as a flat surface, and the weight side follower part is formed as a flat surface that makes surface contact with the cam surface formed as a flat surface.

[0010] According to this, the centrifugal clutch reduces the surface pressure by having the assist cam body and the weight side follower part in face contact, thereby suppressing deterioration or damage to the assist cam body and the weight side follower part, and thereby enabling the centrifugal clutch to exhibit stable cam characteristics over a long period of time.

[0011] Another feature of the present invention is that in the centrifugal clutch, the assist cam body has at least one of the multiple cam surfaces formed by a curved surface, and the weight side follower part is formed by a curved surface that makes surface contact or line contact with the cam surface formed by the curved surface.

[0012] According to this, since the assist cam body of the centrifugal clutch is formed with a convex or concave curved surface, the two can be configured with surface contact or line contact depending on the shape of the weight side driven part. In other words, in the centrifugal clutch according to the present invention, the assist cam body formed with a curved surface can be used in common for centrifugal clutches having weight side driven parts that require surface contact and centrifugal clutches having weight side driven parts that require line contact.

[0013] Another feature of the present invention is that in the centrifugal clutch, the assist cam body is formed such that the lengths of at least two of the multiple cam surfaces in a direction parallel to the central axis of rotation of the assist cam body are different from each other.

[0014] According to this, the centrifugal clutch is formed so that at least two of the multiple cam surfaces that constitute the assist cam body have different lengths in a direction parallel to the central axis of rotation of the assist cam body (i.e., are formed with different shapes), and therefore the cam characteristics, i.e., the clutch characteristics, can be changed by changing the cam surface relative to the weight side follower.

[0015] Another feature of the present invention is that in the centrifugal clutch, the assist cam body is formed such that the distances from the rotational center axis of the assist cam body to at least two of the multiple cam surfaces are different from each other.

[0016] According to this, the centrifugal clutch is formed such that the distances from the rotational axis of the assist cam body to at least two of the multiple cam surfaces constituting the assist cam body are different from each other. Here, the distances of the two cam surfaces from the rotational axis of the assist cam body are the distances to the rotational axis at the positions corresponding to each other on the two cam surfaces, for example, the distances to the nearest parts of the two cam surfaces to the rotational axis of the assist cam body (shortest distances). That is, the assist cam body exists at a position where the rotational axis is eccentric with respect to the outer surface including the cam surface in a cross section perpendicular to the rotational axis direction of the assist cam body. As a result, the centrifugal clutch can change the surface pressure (in other words, the cam thrust) by changing the cam surface for the weight-side driven part, thereby changing the cam characteristics, i.e., the clutch characteristics.

[0017] Another feature of the present invention is that in the centrifugal clutch, the assist cam body is formed in a substantially rectangular shape in a plan view and has two or more and four or less cam surfaces.

[0018] According to this, the centrifugal clutch has an assist cam body formed in a substantially rectangular shape in plan view and has two or more and four or less cam surfaces, so that one assist cam body can exhibit up to four cam characteristics. Note that the term "substantially rectangular" in plan view of the assist cam body does not only mean a strict quadrilateral shape, but also means that the assist cam body is formed in various rectangular shapes such as a square or rectangle even if the corners or sides are strictly curved.

[0019] Another feature of the present invention is that in the centrifugal clutch, the assist cam body is formed in a substantially triangular shape in a plan view and has two or more and three or less cam surfaces.

[0020] According to this, the centrifugal clutch has an assist cam body that is formed into a substantially triangular shape in plan view and has two or three cam surfaces, so that one assist cam body can exhibit up to three cam characteristics. Note that the term "substantially triangular" in plan view of the assist cam body does not only mean a strict triangular shape, but also means that the assist cam body is formed into various triangular shapes such as an equilateral triangle, an isosceles triangle, or a right-angled triangle even if the corners or sides are strictly curved.

[0021] Another feature of the present invention is that in the centrifugal clutch, the assist cam body has at least two of the plurality of cam surfaces each having a different surface roughness.

[0022] According to this, the centrifugal clutch is formed such that the surface roughness of at least two of the multiple cam surfaces that constitute the assist cam body is different from each other, and as a result, the cam characteristics, i.e., the clutch characteristics, can be changed by changing the cam surface relative to the weight side follower.

[0023] Furthermore, the present invention can be embodied not only as an invention of a centrifugal clutch, but also as an invention of a method for restoring or changing the clutch characteristics of a centrifugal clutch.

[0024] Specifically, the method for regenerating or changing the clutch characteristics of a centrifugal clutch includes a drive plate that is rotated by receiving a driving force from a driving source, a plurality of clutch weights that are displaced so as to contact or separate from the cylindrical surface of the clutch outer by the centrifugal force caused by the rotation of the drive plate, an assist cam body having a cam surface and rotatably provided on the drive plate, and a weight-side follower part that is provided on the clutch weight and is pressed by the cam surface of the assist cam body when the clutch weight is displaced, the assist cam body has a plurality of cam surfaces formed thereon, and one of the plurality of cam surfaces presses the weight-side follower part, and the cam characteristics of at least two of the plurality of cam surfaces constituting the assist cam body are formed to be the same or different from each other, and the cam surface of the assist cam body is changed so that the cam surface with the same or different cam characteristics is pressed against the weight-side follower part. According to this, the method for regenerating or changing the clutch characteristics of a centrifugal clutch can be expected to have the same effect as the centrifugal clutch described above. [Brief description of the drawings]

[0025] [Figure 1] 1 is a plan sectional view showing a schematic configuration of a power transmission mechanism including a centrifugal clutch according to the present invention. [Diagram 2] FIG. 2 is a side view of the centrifugal clutch as viewed from line 2-2 shown in FIG. [Diagram 3] 3 is a perspective view showing a state in which an assist cam body is assembled to a drive plate in the centrifugal clutch shown in FIG. 1 and FIG. 2. [Figure 4] 3 is a perspective view showing how a clutch weight is attached to a drive plate in the centrifugal clutch shown in FIG. 1 and FIG. 2. [Diagram 5] 3 is a partial enlarged view showing the centrifugal clutch shown in FIG. 2 in a clutch-off state in which the clutch shoe is not in contact with the clutch outer. [Figure 6]6 is a partial enlarged view showing a clutch-on state in which a clutch shoe is pressed against a clutch outer in the centrifugal clutch shown in FIG. 5. FIG. [Figure 7] 7 is a partial enlarged view showing a state in which a clutch weight in the centrifugal clutch shown in FIG. 6 rotates radially inward of a drive plate. [Figure 8] 6 is a partial enlarged view for explaining a cam angle when a first cam surface of an assist cam body slides on a weight-side driven portion of a clutch weight in the centrifugal clutch shown in FIG. 5. FIG. [Figure 9] 6 is a partial enlarged view for explaining a cam angle when a third cam surface of an assist cam body slides on a weight-side driven portion of a clutch weight in the centrifugal clutch shown in FIG. 5. FIG. [Figure 10] 13 is a plan view showing a schematic external configuration of an assist cam body according to a modified example of the present invention. FIG. [Figure 11] 1A to 1C show schematic external configurations of assist cam bodies according to other modified examples of the present invention, where 1A is a plan view of an assist cam body having a rectangular shape when viewed from above, 1B is a plan view of an assist cam body including an arc-shaped surface on the cam surface, and 1C is a plan view of an assist cam body in which a mounting hole is formed at an eccentric position in the cross section. [Figure 12] 1A to 1C show schematic external configurations of assist cam bodies according to other modified examples of the present invention, where 1A is a plan view of an assist cam body having an equilateral triangular shape when viewed from above, 1B is a plan view of an assist cam body having a cam surface formed into an arc-shaped curved surface, and 1C is a plan view of an assist cam body having a mounting hole formed at an eccentric position in the cross section. [Figure 13] FIG. 13 is a plan view showing a schematic external configuration of an assist cam body according to another modified example of the present invention. [Figure 14] 1A and 1B show schematic views of the external configuration of an assist cam body according to another modified example of the present invention, where 1A is a plan view of an assist cam body having an elliptical shape in plan view, and 1B is a plan view of an assist cam body in which a mounting hole is formed at an eccentric position in the cross section. [Figure 15]FIG. 11 is a perspective view showing the outline of the external configuration of an assist cam body according to another modified example of the present invention. [Figure 16] FIG. 11 is a perspective view showing a state in which an assist cam body according to another modified example of the present invention is attached to a drive plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the centrifugal clutch according to the present invention will be described with reference to the drawings. Fig. 1 is a plan sectional view showing a schematic configuration of a power transmission mechanism 100 including a centrifugal clutch 200 according to the present invention. Fig. 2 is a side view of the centrifugal clutch 200 as seen from line 2-2 shown in Fig. 1. In this case, Fig. 1 shows the upper half of the centrifugal clutch 200 in a state where the movable driven plate 134 is closest to the fixed driven plate 131, and the lower half shows the state where the movable driven plate 134 is farthest from the fixed driven plate 131.

[0027] The power transmission mechanism 100 equipped with this centrifugal clutch 200 is a mechanical device that is provided between an engine and a rear wheel, which is a driving wheel, mainly in a two-wheeled motor vehicle such as a scooter, and transmits or cuts off the rotational driving force to the rear wheel while automatically changing the reduction ratio according to the engine speed. Specifically, the centrifugal clutch 200 is a mechanical device that cuts off the transmission of the rotational driving force to the driven side until the engine reaches a predetermined speed, and transmits the rotational driving force to the driven side when the engine reaches the predetermined speed.

[0028] (Configuration of centrifugal clutch 200) This power transmission mechanism 100 mainly includes a transmission 101 and a centrifugal clutch 200. The transmission 101 is a mechanical device that continuously reduces the rotational driving force from an engine (not shown) and transmits it to the centrifugal clutch 200, and is mainly configured with a drive pulley 110, a V-belt 120, and a driven pulley 130. Of these, the drive pulley 110 is a mechanical device that is provided on a crankshaft 111 extending from the engine and is directly driven to rotate by the rotational driving force of the engine, and is mainly configured with a fixed drive plate 112 and a movable drive plate 113.

[0029] The fixed drive plate 112 is a component that rotates while being held together with the movable drive plate 113 by sandwiching the V-belt 120, and is made of a metal material formed into a conical cylindrical shape. This fixed drive plate 112 is fixedly attached to the crankshaft 111 with the convex surface facing the movable drive plate 113 side (engine side). In other words, the fixed drive plate 112 always rotates integrally with the crankshaft 111. In addition, a plurality of heat dissipation fins 112a are provided on the concave surface of the fixed drive plate 112 radially around the axis of the crankshaft 111.

[0030] The movable drive plate 113 is a component that rotates while being held together with the fixed drive plate 112 by sandwiching the V-belt 120, and is made of a metal material such as aluminum formed into a conical cylindrical shape. The movable drive plate 113 is attached to the crankshaft 111 with its convex surface facing the fixed drive plate 112. In this case, the movable drive plate 113 is attached via an impregnated bush onto a sleeve bearing 114 that is fixedly fitted to the crankshaft 111, and is attached to the sleeve bearing 114 so as to be slidable in both the axial and circumferential directions.

[0031] Meanwhile, a plurality of roller weights 115 are provided on the concave surface of the movable drive plate 113 in a state of being pressed by the ramp plate 116. The roller weights 115 are components for pressing the movable drive plate 113 toward the fixed drive plate 112 in cooperation with the ramp plate 116 by displacing radially outward in response to an increase in the rotation speed of the movable drive plate 113, and are formed by forming a metal material such as aluminum into a cylindrical shape. The ramp plate 116 is a component for pressing the roller weights 115 toward the movable drive plate 113, and is formed by bending a metal plate such as aluminum toward the movable drive plate 113.

[0032] The V-belt 120 is a component for transmitting the rotational driving force of the drive pulley 110 to the driven pulley 130, and is formed in an endless ring shape with a core wire covered with an elastic material such as rubber. The V-belt 120 is disposed between the fixed drive plate 112 and the movable drive plate 113, and between the fixed driven plate 131 and the movable driven plate 134 of the driven pulley 130, and is stretched between the drive pulley 110 and the driven pulley 130.

[0033] The driven pulley 130 is a mechanical device that is rotationally driven by the rotational driving force from the engine transmitted via the drive pulley 110 and the V-belt 120, and is mainly composed of a fixed driven plate 131 and a movable driven plate 134.

[0034] The fixed driven plate 131 is a component that rotates while sandwiching and holding the V-belt 120 together with the movable driven plate 134, and is configured by forming a metal material such as aluminum into a conical cylindrical shape. This fixed driven plate 131 is fixedly attached on the driven sleeve 132 with the convex surface facing the movable driven plate 134 side.

[0035] The driven sleeve 132 is a cylindrical part made of metal (for example, aluminum) that rotates integrally with the fixed driven plate 131, and is attached to the drive shaft 133 via a bearing so as to be relatively rotatable. The drive shaft 133 is a rotating shaft made of metal (for example, steel) that drives the rear wheel of the motorcycle on which the power transmission mechanism 100 is mounted, via a transmission (not shown). In this case, the rear wheel of the motorcycle is attached to one end of the drive shaft 133 (the right side in the figure).

[0036] The movable driven plate 134 is a component that rotates while holding the V-belt 120 together with the fixed driven plate 131, and is configured by forming a metal material such as aluminum into a conical cylindrical shape. The movable driven plate 134 is fitted to the driven sleeve 132 with the convex surface facing the fixed driven plate 131 in a state where it can slide freely in the axial direction.

[0037] On the other hand, a torque spring 135 is provided between the movable driven plate 134 and the drive plate 210 of the centrifugal clutch 200 on the concave side surface of the movable driven plate 134. The torque spring 135 is a coil spring that elastically presses the movable driven plate 134 toward the fixed driven plate 131. That is, this transmission 101 changes the engine speed steplessly depending on the relationship between the diameter of the V-belt 120, which is determined by the distance between the fixed drive plate 112 and the movable drive plate 113, and the diameter of the V-belt 120, which is determined by the distance between the fixed driven plate 131 and the movable driven plate 134. A centrifugal clutch 200 is provided on each tip end side of the driven sleeve 132 and the drive shaft 133.

[0038] The centrifugal clutch 200 is a mechanical device that transmits or cuts off the rotational driving force of the engine transmitted through the transmission 101 to the drive shaft 133, and is mainly composed of a drive plate 210, three clutch weights 240, and a clutch outer 250.

[0039] The drive plate 210 is a component that rotates integrally with the driven sleeve 132, and is configured by forming a metal material such as aluminum into a stepped disk shape. More specifically, as shown in Fig. 3 and Fig. 4, the drive plate 210 is configured by forming a through hole 211a through which the driven sleeve 132 passes in the center of a flat bottom portion 211, and forming a flange-like protruding flange portion 213 at the tip end of a cylindrical portion 212 that stands up around the bottom portion 211. The flange portion 213 is provided with three swing support pins 214, three cam body support pins 217, and three damper receiving pins 230 at equal intervals along the circumferential direction.

[0040] The swing support pin 214 is a part for rotatably supporting one end of the clutch weight 240 described later and swinging the other end, and is composed of a stepped metal rod. In this case, the swing support pin 214 is fixedly attached to the flange 213 by an attachment bolt 214a. The swing support pin 214 supports the clutch weight 240 in a state in which the outer periphery of the swing support pin 214 penetrates the inside of a pin slide hole 241 of the clutch weight 240 via a fulcrum side sliding member 215. In this case, the swing support pin 214 has a side plate 216 attached to the tip end protruding through the pin slide hole 241 by an E-ring 214b, and supports the clutch weight 240 in a state in which the clutch weight 240 is sandwiched between the attachment bolt 214a and the side plate 216.

[0041] The fulcrum side sliding member 215 is a part disposed between the swing support pin 214 and the pin slide hole 241 to improve the sliding property between them, and is configured by forming a resin material into a cylindrical shape. The fulcrum side sliding member 215 is formed with inner and outer diameters that allow it to rotate and slide relative to the swing support pin 214 and the pin slide hole 241, respectively, that is, with dimensional tolerances that provide a clearance fit for the swing support pin 214 and the pin slide hole 241, respectively.

[0042] Moreover, a thermoplastic resin or a thermosetting resin having heat resistance and abrasion resistance can be used as the resin material constituting the fulcrum side sliding member 215, and engineering plastics or super engineering plastics are preferable. Specifically, the thermoplastic resin can be polyether ether ketone resin (PEEK), polyphenylene sulfide resin (PPS), polyamide imide resin (PAI), fluororesin (PTFE) or polyimide resin (PI), and the thermosetting resin can be diallyl phthalate resin (PDAP), epoxy resin (EP) or silicone resin (SI).

[0043] The side plate 216 is a component for preventing the three clutch weights 240 from coming off the swing support pins 214, and is configured by forming a metal material into a ring shape. This side plate 216 is disposed on the opposite side of the drive plate 210 with respect to the three clutch weights 240, facing each of the clutch weights 240.

[0044] The cam body support pin 217 is a component for supporting the assist cam body 220 in a rotatable state, and is made of a stepped metal rod. The cam body support pin 217 is fixedly attached by a mounting bolt 217a onto the flange 213 that faces the portion of the clutch weight 240 closer to the tip end than the pin slide hole 241.

[0045] The assist cam body 220 is a component for generating a cam thrust that presses the clutch weight 240 toward the clutch outer 250, and is configured by forming a resin material into a substantially rectangular tubular shape in a plan view. More specifically, the assist cam body 220 is made of the same resin material as the fulcrum side sliding member 215, and is configured to include a first cam surface 221, a second cam surface 222, a third cam surface 223, a fourth cam surface 224, and an attachment hole 225.

[0046] First cam surface 221, second cam surface 222, third cam surface 223, and fourth cam surface 224 are portions against which weight-side follower portion 245 of clutch weight 240 is pressed and slides, thereby generating a cam thrust force that is a pressing force against clutch weight 240. These first cam surface 221, second cam surface 222, third cam surface 223, and fourth cam surface 224 respectively constitute four side surfaces of assist cam body 220 formed into a substantially square cylinder in a plan view. Here, "substantially" in "substantially rectangular" or "substantially square" means not only a strict rectangular or square shape, but also a substantially rectangular or square shape, and "substantially" hereinafter has the same meaning.

[0047] In this embodiment, the first cam surface 221 and the third cam surface 223 are formed to extend parallel to each other and form side surfaces opposite each other, and the second cam surface 222 and the fourth cam surface 224 extend parallel to each other in directions perpendicular to the first cam surface 221 and the third cam surface 223 and form side surfaces opposite each other. In this case, the first cam surface 221, the second cam surface 222, the third cam surface 223, and the fourth cam surface 224 are formed to have the same shape and the same surface roughness. Also, the assist cam body 220 has four corners each formed into a convex arc curved surface.

[0048] The mounting hole 225 is a through hole through which the cam body support pin 217 provided on the drive plate 210 passes in a rotatable and slidable state, and is formed with an inner diameter that allows the cam body support pin 217 to rotate and slide, that is, with a dimensional tolerance that provides a so-called clearance fit with the cam body support pin 217. The mounting hole 225 is formed at a position shifted from the center of gravity position in a plan view of the assist cam body 220, that is, at an eccentric position. Specifically, the mounting hole 225 is formed at a position between the first cam surface 221 and the third cam surface 223 that is biased toward the third cam surface 223, and with the central position between the second cam surface 222 and the fourth cam surface 224 as the center of a cylinder.

[0049] The damper receiving pin 230 is a component for supporting the damper 231, and is made of a metal rod. The damper 231 is a component that guides the rocking motion that moves the other end side of the clutch weight 240 toward or away from the clutch outer 250, and acts as a buffer when the end is separated from the clutch outer 250, and is made of an elastic body such as a rubber material or an elastomer material formed into a cylindrical shape. The damper 231 is fixedly fitted onto the outer circumferential surface of the damper receiving pin 230.

[0050] The three clutch weights 240 are components for transmitting or blocking the rotational driving force from the engine to the drive shaft 133 by contacting or separating from the clutch outer 250 via the clutch shoe 243 depending on the rotation speed of the drive plate 210, and are formed by forming a metal material (e.g., zinc) into a curved shape extending circumferentially around the drive plate 210.

[0051] Each of these clutch weights 240 has one end supported rotatably by the fulcrum side sliding member 215 and the swing support pin 214 that pass through the pin slide hole 241, and the other end connected to the adjacent clutch weight 240 by a connecting spring 242 made of a metal coil spring and pulled toward the inside of the drive plate 210. In other words, the clutch weight 240 is supported on the drive plate 210 via the swing support pin 214, the fulcrum side sliding member 215, and the pin slide hole 241, with the outer periphery of the other end swingable relative to the clutch outer 250 via the clutch shoe 243.

[0052] In order to make it easier to understand the configuration of the clutch weights 240, one of the three clutch weights 240 is shown cut away at two locations along different thickness directions. Also, in Fig. 2, the rotational drive directions of the drive plate 210 and the clutch outer 250 in the centrifugal clutch 200 are indicated by dashed arrows.

[0053] The pin slide hole 241 is a portion into which the swing support pin 214 of the drive plate 210 is rotatably and slidably fitted, and is constituted by a through hole penetrating in the thickness direction of the clutch weight 240. The pin slide hole 241 is formed in an elongated hole shape so that the one end side of the clutch weight 240 is displaced rearward in the rotation drive direction of the drive plate 210 when the clutch shoe 243 comes into contact with the clutch outer 250. In this embodiment, the pin slide hole 241 is formed to extend in an arc shape toward the front side in the rotation drive direction of the drive plate 210.

[0054] The clutch shoe 243 is a part for increasing the frictional force against the inner peripheral surface of the clutch outer 250, and is configured by forming a friction material into a plate shape extending in an arc shape. The clutch shoe 243 is disposed on the opposite side of the pin slide hole 241 of each clutch weight 240. It is provided on the outer peripheral surface on the tip side.

[0055] In addition, on the surface of each clutch weight 240 facing the drive plate 210, an assist cam body accommodating portion 244 is formed in a concave shape so as to cover the assist cam body 220, and a damper groove 246 is formed in a concave shape so as to cover the damper 231.

[0056] The assist cam body accommodating portion 244 is the portion in which the weight side driven portion 245 that rides on the assist cam body 220 is formed, and is formed in a groove shape that opens onto the inner peripheral surface of the clutch weight 240 and extends radially outward, with the innermost portion being formed in a concave shape so as not to come into contact with the assist cam body 220.

[0057] The weight-side follower 245 is a portion for displacing the clutch weight 240 toward the clutch outer 250 in cooperation with the assist cam body 220, and is configured with a smooth flat surface facing the rear side in the rotational drive direction of the drive plate 210. More specifically, the weight-side follower 245 has a sliding surface that is pressed in surface contact against one of the first cam surface 221 to the fourth cam surface 224 of the assist cam body 220 and is formed on a flat surface that extends linearly rearward and outward in the rotational drive direction of the drive plate 210.

[0058] The damper groove 246 is the part that houses the damper 231 in a sandwiched state, and is formed in a groove shape that opens to the inner surface of the clutch weight 240 and extends while curving along the rotational displacement direction in which the clutch weight 240 approaches or moves away from the clutch outer 250.

[0059] The clutch outer 250 is a part that rotates integrally with the drive shaft 133, and is configured by forming a metal material into a cup shape that covers the outer circumferential surface of the clutch weight 240 from the drive plate 210. In other words, the clutch outer 250 is configured to have a cylindrical surface 251 that comes into frictional contact with the clutch shoe 243 of the clutch weight 240 that is displaced toward the outer circumferential side of the drive plate 210.

[0060] (Assembly of the centrifugal clutch 200) Next, a description will be given of the assembly work of the centrifugal clutch 200 configured as described above. Regarding the assembly work of the centrifugal clutch 200, only the part directly related to the present invention, i.e., the work before and after assembling the assist cam body 220, will be described.

[0061] The worker prepares three assist cam bodies 220 for one drive plate 210. In this case, the drive plate 210 has three swing support pins 214, three cam body support pins 217, and three damper receiving pins 230 cut and provided on the flange portion 213 (see FIG. 3).

[0062] Next, the worker mounts the assist cam body 220 on each of the three cam body support pins 217. Specifically, the worker passes the cam body support pin 217 through the mounting hole 225 in the assist cam body 220. In this case, the worker fits the assist cam body 220 to the cam body support pin 217 in such a manner that any one of the first cam surface 221 to the fourth cam surface 224 of the assist cam body 220 that slides on the weight side follower 245 of the clutch weight 240 faces the weight side follower 245. In this embodiment, the worker fits the assist cam body 220 to the cam body support pin 217 in such a manner that the first cam surface 221 of the assist cam body 220 faces the weight side follower 245 of the clutch weight 240 (see FIG. 4).

[0063] Next, the worker prepares three each of the fulcrum side sliding members 215 and dampers 231, and fits the fulcrum side sliding members 215 to the swing support pins 214, and also fits the dampers 231 to the damper receiving pins 230. Next, the worker prepares three each of the clutch weights 240 and connecting springs 242, and connects the three clutch weights 240 in an annular shape by the connecting springs 242.

[0064] Next, the worker attaches the connected body in which the three clutch weights 240 are connected in an annular shape by the connecting springs 242 to the drive plate 210. Specifically, the worker places the three clutch weights 240 on the drive plate 210 by passing the swing support pins 214 of the drive plate 210 through the pin slide holes 241 in the clutch weights 240. In this case, the assist cam bodies 220 that fit onto the cam body support pins 217 are positioned in the assist cam body accommodating portions 244 of the clutch weights 240, and the dampers 231 that fit onto the damper receiving pins 230 are positioned in the damper grooves 246.

[0065] Next, the worker prepares one side plate 216 and three E-rings 214b, and arranges the side plate 216 so as to cover the three clutch weights 240. In this case, the worker arranges the side plate 216 so that each swing support pin 214 penetrates the side plate 216, and fits the E-ring 214b into the tip of each swing support pin 214 that penetrates the side plate 216, thereby fixing the side plate 216 onto the clutch weight 240. This allows the worker to assemble the main parts of the centrifugal clutch 200.

[0066] (Operation of the centrifugal clutch 200) Next, the operation of the centrifugal clutch 200 configured as described above will be described with reference to Figures 5 to 7. Note that the E-ring 214b, the side plate 216, and the connecting spring 242 are omitted in Figures 5 to 7. Also, in Figures 6 and 7, the rotational drive directions of the drive plate 210 and the clutch outer 250 in the centrifugal clutch 200 are indicated by thick dashed arrows. Also, in Figure 7, the rotational direction of the assist cam body 220 is indicated by thin dashed arrows.

[0067] This centrifugal clutch 200 functions by configuring a part of a power transmission mechanism 100 disposed between an engine and a rear wheel serving as a drive wheel in a motorcycle (e.g., a scooter). First, when the engine is idling, the centrifugal clutch 200 cuts off the transmission of driving force between the engine and the drive shaft 133, as shown in Fig. 5. Specifically, in the centrifugal clutch 200, a drive plate 210 is rotationally driven by the rotational driving force of the engine transmitted via the transmission 101, and thus a clutch weight 240 is rotationally driven.

[0068] However, in this case, the centrifugal clutch 200 is in a clutch-off state in which the centrifugal force acting on the clutch weight 240 is smaller than the elastic force (tensile force) of the connecting spring 242, and the clutch shoe 243 does not contact the cylindrical surface 251 of the clutch outer 250, and the rotational driving force of the engine is not transmitted to the drive shaft 133. In this clutch-off state, the weight-side driven part 245 is pressed against the first cam surface 221 of the assist cam body 220 by the elastic force (tensile force) of the connecting spring 242, and maintains a state of contact.

[0069] In addition, in this clutch-off state, the clutch weight 240 is pulled by the tensile force of the connecting spring 242 (the connecting spring 242 hooked at a position adjacent to the weight-side driven part 245) which pulls from a position farther from the swing support pin 214 out of the two connected connecting springs 242. In this case, since the pin slide hole 241 is formed in an elongated hole shape, the clutch weight 240 is displaced toward the connecting spring 242 hooked at a position adjacent to the weight-side driven part 245. As a result, the swing support pin 214 is positioned at the rear end of the pin slide hole 241 in the rotational drive direction of the drive plate 210 (see FIG. 5).

[0070] Next, the centrifugal clutch 200 transmits the rotational driving force of the engine to the drive shaft 133 in response to an increase in engine speed due to an accelerator operation by the rider of the motorcycle. Specifically, in the centrifugal clutch 200, as the engine speed increases, the centrifugal force acting on the clutch weight 240 becomes greater than the elastic force (tensile force) of the connecting spring 242, and the clutch weight 240 is rotationally displaced radially outward around the swing support pin 214. That is, as shown in FIG. 6, in the centrifugal clutch 200, as the engine speed increases, the clutch weight 240 is rotationally displaced toward the cylindrical surface 251 of the clutch outer 250 while resisting both the elastic force of the connecting spring 242 and the sliding resistance between the damper 231 and the damper groove 246, and as a result, the clutch shoe 243 comes into contact with the cylindrical surface 251.

[0071] When the clutch shoe 243 comes into contact with the cylindrical surface 251, the clutch weight 240 receives a reaction force in the opposite direction to the rotational drive direction via the clutch shoe 243. In this case, the pin slide hole 241 is formed in an elongated hole shape along the circumferential direction of the drive plate 210, and the swing support pin 214 is located at the rear end of the pin slide hole 241 in the rotational drive direction of the drive plate 210. In other words, since the clutch weight 240 is in a state in which displacement toward the rear side in the rotational drive direction of the drive plate 210 is permitted, the clutch weight 240 is relatively displaced in the opposite direction to the rotational drive direction of the drive plate 210 by the reaction force received via the clutch shoe 243.

[0072] As a result, the weight-side follower 245 formed on the clutch weight 240 is strongly pressed against the assist cam body 220 as shown in Fig. 7. In this case, since the assist cam body 220 is rotatably supported by the cam body support pin 217, it rotates counterclockwise as shown in the figure due to the pressure from the weight-side follower 245 (see the thin dashed arrow in Fig. 7). As a result, the clutch weight 240 is pressed toward the clutch outer 250 on the radially outer side as the weight-side follower 245 rides up onto the assist cam body 220 while rotating the assist cam body 220, and the clutch shoe 243 is pressed against the cylindrical surface 251.

[0073] As a result, in the centrifugal clutch 200, after the clutch shoe 243 comes into contact with the cylindrical surface 251 of the clutch outer 250, the clutch shoe 243 is pressed against the cylindrical surface 251 in an extremely short time (in other words, instantaneously), and the clutch weight 240 is inserted in a wedge shape between the assist cam body 220 and the clutch outer 250. This causes the centrifugal clutch 200 to enter a clutch-on state in which the rotational driving force of the engine is completely transmitted to the drive shaft 133.

[0074] In this clutch-on state, the centrifugal clutch 200 maintains a state in which the clutch shoe 243 is pressed against the cylindrical surface 251 of the clutch outer 250, so that the drive plate 210 and the clutch outer 250 rotate together. This allows the motorcycle to run by rotating the rear wheel using the rotational driving force of the engine.

[0075] On the other hand, when the engine speed decreases, the centrifugal clutch 200 cuts off the transmission of the rotational driving force of the engine to the drive shaft 133. Specifically, as the engine speed decreases, the centrifugal force acting on the clutch weight 240 becomes smaller than the elastic force (tensile force) of the connecting spring 242, and the clutch weight 240 rotates radially inward around the swing support pin 214.

[0076] In this case, the pin slide hole 241 is formed in an elongated hole shape along the circumferential direction of the drive plate 210, and the swing support pin 214 is located slightly forward of the rear end of the pin slide hole 241 in the rotational drive direction of the drive plate 210. In other words, since the clutch weight 240 is in a state in which displacement toward the front side in the rotational drive direction of the drive plate 210 is permitted, the elastic force (tensile force) of the connecting spring 242 causes the clutch weight 240 to rotate relatively to the drive plate 210 toward the front in the rotational drive direction of the drive plate 210.

[0077] As a result, the clutch weight 240 is rotationally displaced forward in the rotational drive direction of the drive plate 210 and radially inward while the weight-side driven part 245 rotates the assist cam body 220 clockwise in the figure, and returns to its original position (the position during idling) (see FIG. 5). In other words, the centrifugal clutch 200 is in a clutch-off state in which the clutch shoe 243 does not contact the clutch outer 250 and does not transmit the rotational drive force.

[0078] Next, a description will be given of changing the cam surface of the assist cam body 220. This centrifugal clutch 200 can reproduce or change the cam characteristics by changing the orientation of the assist cam body 220 incorporated in the centrifugal clutch 200 and changing the cam surfaces (first cam surface 221, second cam surface 222, third cam surface 223, and fourth cam surface 224) that press the weight side follower part 245.

[0079] Specifically, the worker removes the centrifugal clutch 200 from the motorcycle in which it is installed, and then removes the side plate 216. Next, the worker removes the three clutch weights 240 connected by the connecting spring 242 from the drive plate 210. This exposes the three assist cam bodies 220 on the drive plate 210 (see FIGS. 3 and 4).

[0080] Next, the worker rotates the assist cam body 220 held by the cam body support pin 217 around the axis of the cam body support pin 217. In this case, the worker rotates the assist cam body 220 in a direction in which any one of the second cam surface 222, the third cam surface 223, and the fourth cam surface 224 faces the weight-side driven part 245 of the clutch weight 240. Here, the second cam surface 222, the third cam surface 223, and the fourth cam surface 224 are formed at different positions relative to the rotation center axis O (the center axis of the mounting hole 225) from the first cam surface 221, so that the cam characteristics can be changed. It is to be noted that the worker may of course remove the assist cam body 220 held by the cam body support pin 217, change the orientation, and hold it again by the cam body support pin 217.

[0081] In this embodiment, the worker rotates the assist cam body 220 around the axis of the cam body support pin 217 so that the third cam surface 223 faces the weight-side driven portion 245 of the clutch weight 240. In this case, the worker rotates all three assist cam bodies 220 so that the same cam surface faces the weight-side driven portion 245. Then, the worker attaches the clutch weight 240 and the side plate 216 in the same manner as in the assembling work of the centrifugal clutch 200 described above to complete the centrifugal clutch 200, and then installs the centrifugal clutch 200 back into the motorcycle vehicle.

[0082] This allows the operator to change the clutch characteristics by changing the cam characteristics in the centrifugal clutch 200. Specifically, in the centrifugal clutch 200, when the assist cam body 220 is set (oriented) so that the first cam surface 221 faces the weight-side driven part 245 as shown in Fig. 8 and Fig. 9, the cam angle is larger and the cam thrust is reduced compared to when the assist cam body 220 is set (oriented) so that the first cam surface 221 faces the weight-side driven part 245, so that the pressing force with which the clutch weight 240 presses the clutch outer 250 can be reduced. That is, the first cam surface 221, the second cam surface 222, the third cam surface 223, and the fourth cam surface 224 correspond to the cam surfaces according to the present invention.

[0083] Here, the cam angle is the angle between a normal to a line passing through a sliding portion where the assist cam body 220 and the weight side follower 245 contact each other and the rotation drive center of the drive plate 210, and a sliding direction line at the sliding portion. In this case, if the sliding portion is a surface contact, it is the center position of the length of the sliding portion in the sliding direction. Also, if at least one of the assist cam body 220 and the weight side follower 245 is a curved surface, the sliding direction line is a tangent to the curved surface at the sliding portion. The larger the cam angle, the smaller the assist thrust, and the smaller the cam angle, the greater the assist thrust.

[0084] In this embodiment, the first cam surface 221 in the assist cam body 220 is changed to a third cam surface 223. This makes it possible to change the cam characteristics generated between the assist cam body 220 and the weight side follower 245. However, the assist cam body 220 has the second cam surface 222 and the fourth cam surface 224 formed to have the same shape and at the same formation position relative to the rotation center axis O (the center axis of the mounting hole 225). Therefore, the assist cam body 220 can maintain or reproduce the same cam characteristics by changing between the second cam surface 222 and the fourth cam surface 224.

[0085] As can be understood from the above operation description, according to the above embodiment, centrifugal clutch 200 has multiple cam surfaces formed on assist cam body 220, from first cam surface 221 to fourth cam surface 224, so that the desired cam characteristics can be obtained by setting (orienting) the desired cam surface on drive plate 210 so that it faces weight side follower portion 245, and the replacement work of assist cam body 220 or the assembly work of centrifugal clutch 200 can be simplified.

[0086] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention. In the description of each modification, the same reference numerals are used to designate the same parts as those in the above-described embodiment, and redundant description will be omitted.

[0087] For example, in the above embodiment, the assist cam body 220 has the mounting hole 225, which serves as the rotational axis O of the assist cam body 220, formed at a position offset toward the third cam surface 223 between the first cam surface 221 and the third cam surface 223 in a plan view, and at a central position between the second cam surface 222 and the fourth cam surface 224. However, the assist cam body 220 may also have the mounting hole 225, which serves as the rotational axis O of the assist cam body 220, formed at a central position between the first cam surface 221 and the third cam surface 223 in a plan view, and at a position offset to one side between the second cam surface 222 and the fourth cam surface 224.

[0088] That is, the centrifugal clutch 200 can be formed such that the distances from the rotation center axis O of the assist cam body 220 to at least two of the multiple cam surfaces constituting the assist cam body 220 are different from each other. In other words, the centrifugal clutch 200 can be configured such that the rotation center axis O of the assist cam body 220 passes through a position different from the position of the center of gravity in a cross section perpendicular to the rotation center axis O of the assist cam body 220. Therefore, the assist cam body 220 can also be formed such that the mounting hole 225 serving as the rotation center axis O of the assist cam body 220 is at a position offset to one side between the first cam surface 221 and the third cam surface 223, and at a position offset to one side between the second cam surface 222 and the fourth cam surface 224 in a plan view.

[0089] On the other hand, the centrifugal clutch 200 can be formed such that the distances from the rotational center axis O of the assist cam body 220 to the multiple cam surfaces constituting the assist cam body 220 are the same. That is, the centrifugal clutch 200 can be configured such that the rotational center axis O of the assist cam body 220 passes through the center of gravity position in a cross section perpendicular to the rotational center axis O of the assist cam body 220. Specifically, as shown in FIG. 10, the assist cam body 220 can be provided with mounting holes 225 at positions equidistant from the first cam surface 221, the second cam surface 222, the third cam surface 223 and the fourth cam surface 224. According to this, the assist cam body 220 can be configured to have four cam surfaces (the first cam surface 221, the second cam surface 222, the third cam surface 223 and the fourth cam surface 224) having the same cam characteristics.

[0090] In the above embodiment, the assist cam body 220 is provided with the first cam surface 221 to the fourth cam surface 224 and is formed into a substantially square shape in a plan view. That is, the assist cam body 220 is provided with four cam surfaces and is formed into a substantially rectangular shape in a plan view. However, the assist cam body 220 may be configured with a plurality of (at least two) cam surfaces. Therefore, the assist cam body 220 can be configured into various shapes such as a substantially rectangular shape other than a substantially square shape in a plan view, a substantially polygonal shape such as a triangle or a pentagon, a substantially elliptical shape, or an irregular shape.

[0091] Specifically, the assist cam body 220 can be formed into a substantially rectangular shape in a plan view, as shown in Fig. 11(A) to (C). In this case, the first cam surface 221, the second cam surface 222, the third cam surface 223 and the fourth cam surface 224 can be formed as flat surfaces extending linearly as shown in Fig. 11(A), and some or all of the cam surfaces can be formed as curved surfaces curved convexly (or concavely) as shown in Fig. 11(B). Also, the assist cam body 220 can have a mounting hole 225, which is the center of rotation, formed at an eccentric position in a cross section of the assist cam body 220 (a cross section perpendicular to the central axis of rotation O), as shown in Fig. 11(C).

[0092] Also, for example, the assist cam body 220 can be formed in a substantially triangular shape in a plan view, as shown in Figs. 12(A) to (C). In this case, the first cam surface 221, the second cam surface 222, and the third cam surface 223 can be formed in a flat plane extending in a straight line as shown in Fig. 12(A), and a part or all of the cam surfaces can be formed in a curved surface curved in a convex (or concave) shape as shown in Fig. 12(B). The assist cam body 220 can be formed in an isosceles triangle or a right triangle in a plan view, in addition to an equilateral triangle. Also, the assist cam body 220 can be formed in an eccentric position in a transverse section (a section perpendicular to the central axis of rotation O) of the assist cam body 220, as shown in Fig. 12(C).

[0093] Also, for example, the assist cam body 220 can be formed into a polygonal shape such as a substantially pentagonal shape in a plan view as shown in Fig. 13. In this case, the first cam surface 221, the second cam surface 222, the third cam surface 223, the fourth cam surface 224 and the fifth cam surface 226 can be formed into a flat surface extending linearly or a curved surface curving convexly (or concavely). Also, the assist cam body 220 can have a mounting hole 225, which serves as the center of rotation, formed at an eccentric position in a transverse section of the assist cam body 220 (a section perpendicular to the central axis of rotation O).

[0094] Also, for example, the assist cam body 220 can be formed in an elliptical shape as shown in Fig. 14(A). In this case, the assist cam body 220 can also be formed with the mounting hole 225, which serves as the center of rotation, at an eccentric position in the transverse section (cross section perpendicular to the central axis of rotation O) of the assist cam body 220 as shown in Fig. 14(B).

[0095] Also, in the above embodiment, assist cam body 220 is configured so that the lengths in the direction parallel to rotation center axis O of first cam surface 221, second cam surface 222, third cam surface 223, and fourth cam surface 224 are the same. However, assist cam body 220 can also be configured so that the lengths in the direction parallel to rotation center axis O of at least two cam surfaces among a plurality of cam surfaces such as first cam surface 221, second cam surface 222, third cam surface 223, and fourth cam surface 224 are different from each other.

[0096] For example, in the assist cam body 220, the axial length of the mounting hole 225 in the fourth cam surface 224 can be formed shorter than the lengths of the other cam surfaces, as shown in Fig. 15. As a result, the centrifugal clutch 200 is formed with different shapes between the two cam surfaces, and therefore the cam surface for the weight-side follower 245 is changed, thereby making it possible to change the cam characteristics, i.e., the clutch characteristics.

[0097] In the above embodiment, the assist cam body 220 is formed so that the surface roughness of the first cam surface 221, the second cam surface 222, the third cam surface 223, and the fourth cam surface 224 is all the same. However, the assist cam body 220 can also be formed so that the surface roughness of at least two of the multiple cam surfaces, such as the first cam surface 221, the second cam surface 222, the third cam surface 223, and the fourth cam surface 224, is different from one another. As a result, the centrifugal clutch 200 has different surface roughness between the two cam surfaces, and therefore the cam characteristics, i.e., the clutch characteristics, can be changed by changing the cam surface for the weight-side follower 245.

[0098] Also, in the above embodiment, the assist cam body 220 is configured to be rotatably held by the cam body support pin 217 standing on the drive plate 210. However, it is sufficient that the assist cam body 220 is rotatably supported on the drive plate 210. Therefore, the assist cam body 220 can be configured, for example, as shown in FIG. 16, to have a shaft portion 227 corresponding to the cam body support pin 217 protruding from the lower surface of the assist cam body 220, and to have the shaft portion 227 rotatably attached to an attachment hole 218 formed in the drive plate 210.

[0099] Also, in the above embodiment, the assist cam body 220 is rotatably supported so as to rotate freely over 360° relative to the drive plate 210. However, the assist cam body 220 may be rotatably supported so as to swing within a range in which it operates as a cam between the clutch weight 240, that is, within a range of 360° or less. In other words, the rotation of the assist cam body 220 includes forward and reverse rotation on the drive plate 210 at an angle of 360° or more, and forward and reverse rotation within an angle range of less than 360°.

[0100] In the above embodiment, the centrifugal clutch 200 is configured to be driven by the driving force output by the engine, which is an internal combustion engine. However, the centrifugal clutch 200 can also be configured to be driven by the driving force output by a driving source other than the engine, for example, an electric motor.

[0101] In the above embodiment, the centrifugal clutch 200 is configured to receive the rotational driving force output by the engine via the transmission 101. However, the centrifugal clutch 200 can also receive the driving force without passing through the transmission 101. For example, the centrifugal clutch 200 can also be configured to receive the driving force directly from the driving source and drive the drive plate 210 via an input member (for example, a pulley such as the driven pulley 130 or a mechanical element such as a gear) that rotates the drive plate 210. In other words, the centrifugal clutch 200 only needs to be configured to receive the driving force directly or indirectly from the driving source and drive the drive plate 210. [Explanation of symbols]

[0102] O: Rotational center axis of the assist cam body, 100...power transmission mechanism, 101...transmission, 110... drive pulley, 111... crankshaft, 112... fixed drive plate, 112a... heat dissipation fin, 113... movable drive plate, 114... sleeve bearing, 115... roller weight, 116... ramp plate, 120…V-belt, 130... driven pulley, 131... fixed driven plate, 132... driven sleeve, 133... drive shaft, 134... movable driven plate, 135... torque spring, 200…Centrifugal clutch, 210...drive plate, 211...bottom, 211a...through hole, 212...tubular portion, 213...flange portion, 214...oscillation support pin, 214a...mounting bolt, 214b...E-ring, 215...fulcrum side sliding member, 216...side plate, 217...cam body support pin, 217a...mounting bolt, 218...mounting hole, 220...assist cam body, 221...first cam surface, 222...second cam surface, 223...third cam surface, 224...fourth cam surface, 225...mounting hole, 226...fifth cam surface, 227...shaft portion, 230...damper receiving pin, 231...damper, 240: clutch weight; 241: pin slide hole; 242: connecting spring; 243: clutch shoe; 244: assist cam body accommodating portion; 245: weight side follower portion; 246: damper groove; 250...clutch outer, 251...cylindrical surface.

Claims

1. a drive plate that is rotationally driven by a driving force from a driving source; a plurality of clutch weights that are displaced so as to come into contact with or separate from a cylindrical surface of the clutch outer by centrifugal force caused by rotation of the drive plate; an assist cam body having a cam surface and rotatably provided on the drive plate; a weight-side follower portion provided on the clutch weight and pressed by the cam surface of the assist cam body when the clutch weight is displaced, The assist cam body is A centrifugal clutch, characterized in that a plurality of cam surfaces are formed, and one of the plurality of cam surfaces presses against the weight-side driven portion.

2. 2. The centrifugal clutch according to claim 1, The assist cam body is At least one of the plurality of cam surfaces is formed as a flat surface, The weight side follower portion is A centrifugal clutch comprising a flat surface that comes into surface contact with the cam surface that is formed of the flat surface.

3. 2. The centrifugal clutch according to claim 1, The assist cam body is At least one of the plurality of cam surfaces is formed of a curved surface, The weight side follower portion is A centrifugal clutch comprising a curved surface that makes surface contact or line contact with the cam surface that is formed of the curved surface.

4. 2. The centrifugal clutch according to claim 1, The assist cam body is A centrifugal clutch, characterized in that at least two of the plurality of cam surfaces are formed to have mutually different lengths in a direction parallel to the rotational center axis of the assist cam body.

5. 2. The centrifugal clutch according to claim 1, The assist cam body is A centrifugal clutch, characterized in that at least two of the plurality of cam surfaces are formed at different distances from each other to a rotational center axis of the assist cam body.

6. 2. The centrifugal clutch according to claim 1, The assist cam body is A centrifugal clutch characterized in that the cam surfaces are formed in a substantially rectangular shape when viewed from above and include two or more and four or less cam surfaces.

7. 2. The centrifugal clutch according to claim 1, The assist cam body is A centrifugal clutch, characterized in that the cam surfaces are formed in a substantially triangular shape in a plan view and include two or more and three or less cam surfaces.

8. 2. The centrifugal clutch according to claim 1, The assist cam body is A centrifugal clutch, characterized in that at least two of the plurality of cam surfaces have different surface roughnesses from each other.

9. a drive plate that is rotationally driven by a driving force from a driving source; a plurality of clutch weights that are displaced so as to come into contact with or separate from a cylindrical surface of the clutch outer by centrifugal force caused by rotation of the drive plate; an assist cam body having a cam surface and rotatably provided on the drive plate; a weight-side follower portion provided on the clutch weight and pressed by the cam surface of the assist cam body when the clutch weight is displaced, The assist cam body is A method for restoring or changing clutch characteristics in a centrifugal clutch, in which a plurality of cam surfaces are formed and one of the plurality of cam surfaces presses against the weight-side driven part, comprising the steps of: A method for regenerating or changing clutch characteristics in a centrifugal clutch, characterized in that the cam characteristics of at least two of the multiple cam surfaces constituting the assist cam body are formed to be the same or different from each other, and the cam surface of the assist cam body is changed so as to press the cam surface having the same or different cam characteristics against the weight side follower portion.

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