JPH0320588Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a centrifugal clutch that increases or decreases transmitted torque depending on the magnitude of centrifugal force.

(Prior art) For example, in small two-wheeled or three-wheeled vehicles, the engine crankshaft (input shaft)
Some have a centrifugal clutch between the end and the output gear.

In this case, the centrifugal clutch has a structure between the clutch housing, which rotates together with the crankshaft, and the clutch hub, which transmits power to the output extraction gear.
A clutch plate and a friction plate are arranged to face each other.

In this case, a clutch plate is provided on the inner periphery of the clutch housing, and a friction plate is provided on the outer periphery of the clutch hub.

In addition, in the centrifugal clutch, a ball-type transmission torque increase/decrease means, for example, as shown in FIG. Alternatively, a coil type transmission torque increasing/decreasing means disclosed in FIG. 2 of the above-mentioned publication is provided.

In this case, the centrifugal clutch is provided with a spring member that presses the clutch plate and the friction plate into contact with each other, and is also provided with means for separating both plates from the outside in response to a foot operation.

In such a centrifugal clutch, the transmission torque increasing/decreasing means moves in the outer circumferential direction under the action of centrifugal force and rides on the inclined cam surface formed on the inner surface of the clutch housing toward the clutch plate, thereby causing friction between the clutch plate and the clutch plate. Bring the plate into pressure contact (clutch IN). From that point on, the clutch plate and friction plate begin to slip, and when the rotational speed increases from clutch IN to a certain level, the transmission torque increase/decrease means generates a stronger centrifugal force, causing the above slip to reach the upper limit (stall). state), and in the rotation range exceeding the stall state, torque is transmitted without slipping.

The clutch IN and stall rotational speeds, that is, the specifications of the transmission torque increase/decrease means, are already determined at the factory depending on the vehicle model, and therefore cannot normally be changed by the user after the fact.

This also applies to, for example, small two-wheeled motor vehicles.

However, in the case of small motorcycles, which are ridden not only by male riders but also by many female riders, as mentioned above, the clutch IN rotation speed is adjusted at the factory to 20 km/h when the top gear is running.
at 2000rpm and the stall rotation speed at 30Km/h.
If you set it to 3000rpm, the engine speed will be lower than 3000rpm for female riders, as they often travel at much slower speeds than male riders, in other words, in the above example, at 30km/h or less. , the centrifugal clutch will always run in a slippery state in the slipping range between clutch IN and stall.

For such specific two-wheeled motor vehicles, in order to prevent overheating of the clutch facing, a sintered metal-based friction material that has good heat resistance but a small coefficient of friction may be used.

However, since the coefficient of friction is small, in order to ensure the desired torque transmission, if sintered metal is used as the friction material, it is necessary to strengthen the spring member that presses the two plates, and the centrifugal force It is necessary to increase the pressure welding force applied.

However, when the spring force of the spring member is increased,
Conversely, the operating force required to disengage the clutch increases.

This is inconvenient for female riders who have weak foot pedal strength.

Furthermore, in order to obtain strong contact force and centrifugal force, it is necessary to increase the size of the transmission torque increasing/decreasing means, that is, the centrifugal weight, resulting in an increase in the size of the entire clutch.

Therefore, it is sufficient to use a cork-based material with a large friction coefficient as the friction material, but on the other hand, cork-based friction materials tend to generate heat.

(Purpose of the invention) This invention was made in view of the above circumstances,
The purpose of the present invention is to provide a centrifugal clutch capable of transmitting strong torque with light operating force without overheating.

(Structure and effect of the invention) The centrifugal clutch according to this invention has a friction material with high frictional resistance interposed on the sliding surface of a laminated body consisting of a plurality of clutch plates and friction plates, and this friction material is used as the friction material. The locking piece of the clutch plate, which is attached to the plate and is locked to a plurality of ridges extending in the axial direction of the clutch housing, is formed with a contact surface that tightly contacts the outer peripheral wall of the clutch housing and the ridges. It is characterized by the formation of a thick bulge.

According to the above configuration, since a friction material with high frictional resistance is interposed on the sliding surface of the laminated body consisting of a plurality of clutch plates and friction plates,
Even with a light operating force, it is possible to increase the pressing force of the laminated body and to strengthen the torque transmission between the clutch plate and the friction plate.

On the other hand, since a thick bulge is formed on the locking piece of the clutch plate and the locking piece is brought into close contact with the outer circumferential wall and the protrusion of the clutch housing, the area of contact is increased and the clutch plate Thermal conductivity between the locking piece and the clutch housing can be improved.

Therefore, even if the pressure contact force of the laminate is increased to strengthen the torque transmission between the clutch plate and the friction plate, the heat generated from the pressure contact surface is generated due to the close contact between the clutch plate and clutch housing, which have good thermal conductivity. Heat can be dissipated from the outer circumference and side walls of the clutch housing through the surfaces.

In particular, since the clutch housing constitutes the outer shell of the centrifugal clutch and has a much larger surface area than other structural members, its heat dissipation effect is remarkable.

Therefore, even with strong torque transmission, overheating of the sliding surfaces between the clutch plate and the friction plate can be effectively prevented.

(Example) An example of this invention will be described below with reference to the drawings.

FIG. 1 shows an example of a small two-wheeled motor vehicle.

In FIG. 1, 1 is a crankcase, and one side of this crankcase 1 is illustrated. A crankshaft (input shaft) 2 is rotatably supported in the crankcase 1, and a countershaft 3 and a power take-off shaft 4 are each rotatably supported in parallel with the crankshaft 2.

In the above-mentioned countershaft 3, variable speed drive gears 5A, 5B, and 5C from the first stage to the third stage are arranged in the drawing, and a buffer spring 6 is installed at the end of the countershaft 3 that corresponds to the outside of the crankcase 1. A second output extraction gear 7 is attached.

On the other hand, the power take-off shaft 4 has the above-mentioned speed change drive gear 5.
Shift driven gears 8A, 8B, and 8C that mesh with gears A, 5B, and 5C, respectively, are arranged, and thus constitute a transmission capable of shifting gears including gears not shown.

Here, a kick device (not shown) is connected to the first speed change driven gear 8A disposed at the right end of the power take-off shaft 4 in the drawing.

On the other hand, a clutch cover 9 is attached to one side of the crankcase 1, and a centrifugal clutch C, which will be described below, is disposed within the clutch cover 9.

The centrifugal clutch C is provided at the end of the crankshaft 2, and its main members are as follows.

In other words, 10 is the clutch housing, 11, 2
Numerals 3 and 25 are metal clutch plates arranged rotatably within a plane orthogonal to the axis of the crankshaft 2, and 12 are the respective clutch plates 2 mentioned above.
Friction plates are interposed between 3, 11, and 25 and rotatable in a plane perpendicular to the axis of the crankshaft 2, 13 is a clutch hub, 14 is an internal gear, and 15 is a friction plate that responds to centrifugal force. Laminated body A consisting of clutch plates 11, 23, 25 and friction plate 12
A means for variably controlling the pressure contact force, such as a garter spring, is shown.

Among the main members mentioned above, the clutch housing 10 is made of die-cast aluminum, and its inner periphery is connected to the end of the crankshaft 2 by a spline, and is prevented from coming off by a nut 16.

This clutch housing 10 includes a central housing boss 17 and a housing side wall 1 on its outer periphery.
8 and the outermost housing outer peripheral wall 19, and an annular recess 40 is formed around the axis. Here, a spring receiver 20 for setting the garter spring 15 is provided protruding from the inner wall of the housing side wall 18, and a spring receiver 20 has a spring receiver 20 extending toward the outer periphery at a location corresponding to the outer periphery of the spring receiver 20. A cam surface 21 is formed which is inclined in the direction of the clutch plate 11. This cam surface 21 forms a conical surface as a whole. Note that numeral 39 in FIG. 4 indicates a plurality of weight bodies disposed inside the garter spring 15.

On the other hand, as shown in FIG. 2, housing side protrusions 22 are provided on the inner circumferential portion of the housing outer circumferential wall 19, extending in the axial direction and projecting in an intermittent arrangement in the circumferential direction. As shown in FIG. 1, on the protrusion 22, from the garter spring 15 side, a first end clutch plate 23, two intermediate clutch plates 11, 11, and a second end clutch plate 25 are attached in the above order. engaged and arranged;
Each is slidable only in the axial direction.

Here, 26 is a snap ring, which is provided on the housing side protrusion 22, and between this snap ring 26 and the second end clutch plate 25 is a disc spring (clutch plate 11 and flick spring) that biases the clutch in the ON direction. Shion plate 12
A spring member) 27 that presses the
In order to bias the second end clutch plate 25 in the direction of clutch OFF against this disc spring 27,
A release pin (means for separating the clutch plate 11 and friction plate 12) 29 is provided on the guide boss 28 between the housing side protrusions 22,
This release pin 29 is actuated by a clutch operating mechanism 30 that is actuated to move forward and backward in response to foot operation.

Furthermore, locking pawls 31 are formed on the outer periphery of the clutch hub 13, and the friction plates 12 are arranged on these locking pawls 31 so as to be slidable in the axial direction. This friction plate 12
In this example, SPCC is used as a core material, and a friction material 32 having high frictional resistance, for example, a cork-based friction material 32, is provided on both side surfaces and the outer peripheral end surface.

Here, a pressing flange 33 that faces the friction plate 12 is protruded from one end of the outer periphery of the clutch hub 13, and as shown in FIG. The buffer notch grooves 34 are formed in an equally divided arrangement.

Connecting cam grooves 35 are formed between the buffer notch grooves 34, and each connecting cam groove 35 has an engaging cam 36 provided on the outer periphery of the internal gear 14 (FIG. 1). They are slidably engaged. In this case, the starting operation by the above-mentioned kick device causes the first output on the outer periphery of the crankshaft 2 to be output via the first variable speed driven gear 8A, the first variable speed driving gear 5A, and the second output extraction gear 7, as shown in FIG. The operating force is transmitted to the extraction gear 37, and the rotational force is transmitted from the first output extraction gear 37 to the internal gear 14, so that the engagement cam 36 formed on the internal gear 14 engages the connecting cam groove 35.
The vehicle rides on the upper surface 38 of the vehicle as it rotates. As a result, the state shown in Fig. 3 changes to the state shown in Fig. 2, so that the clutch hub 1
3 is moved to the left in FIG. 1, and at this time, the pressing flange 33 presses the friction plate 12, turning the clutch ON and starting the engine.

On the other hand, when the engine is started, the direction of power transmission from the crankshaft 2 through the clutch housing 10 is reversed, so that the starting state shown in FIG. 2 returns to the normal transmission state shown in FIG. 3.

As described above, the centrifugal clutch C is constructed, but here, in particular, the friction plate 1
2 and each of the intermediate clutch plates 11 interposed between the friction plates 12 described above.

That is, the friction plate 12 is interposed on the sliding surface a of the laminate A and is coated with a friction material 32 having high frictional resistance. Also,
The clutch plate 11, as shown in FIG.
Each locking piece 11a that is slidably locked to the protrusion 22 of the clutch housing 10 in the axial direction has a bulge 1.
1a-1 and 11a-1 project in the axial direction, and a large contact surface 11a-2 that contacts the outer peripheral wall 19 and the protrusion 22 of the clutch housing 10 is formed on this locking piece. ing. In the embodiment, the locking piece 11a of the clutch plate 11
The protruding portions 11a-1, 11a-1 are provided so as to be approximately three times thicker than the portions excluding the portions. This thickening target is friction material 3
2, and generates more frictional heat than the first end clutch plate 23 and the second end clutch plate 25.
1, and these intermediate clutch plates 11 are made of aluminum die-casting.

Therefore, with the above structure, since a friction material with high frictional resistance is interposed on the sliding surface of the laminate A made up of a plurality of clutch plates and friction plates, the laminate A can be moved with a light operating force.
The clutch plates 23, 11,
Torque transmission between 25 and friction plate 12 can be strengthened.

On the other hand, the locking piece 11 of the clutch plate 11
thick bulges 11a-1, 11a-1 are formed on the portion a, and the contact surface 11a-2 formed on the locking piece 11a is attached to the inner surface of the outer peripheral wall 19 of the clutch housing 10 and the protrusion 22. Since the structure is configured so that they come into close contact with each other, the contact area increases, and the locking piece 11a of the clutch plate 11 and the clutch housing 10
Thermal conductivity between the two can be improved.

Therefore, even if the pressure contact force of the laminate A is increased to strengthen the torque transmission between the clutch plates 11, 23, 25 and the friction plate 12, the heat generated from the pressure contact surfaces is transferred to the clutch, which has good thermal conductivity. Heat can be radiated from the outer peripheral wall 19 and side wall 18 of the clutch housing 10 through the contact surface 11a-2 between the plate 11 and the clutch housing 10.

In particular, since the clutch housing 10 constitutes the outer shell of the centrifugal clutch C and has a much larger surface area than other constituent members, its heat dissipation effect is remarkable.

Therefore, even with strong torque transmission, and even when a female rider rides at a normal rotation speed below the above-mentioned stall rotation speed, overheating of the sliding contact surface between the clutch plate and friction plate can be effectively prevented. It can be prevented.

In the above, the reason why the thickness of the outer periphery of the clutch plate 11 can be increased is due to the presence of spaces formed on both sides of the outer periphery of the friction plate 12. As a result, the centrifugal clutch C can be made larger. It will not change.

Furthermore, if the intermediate clutch plate 11 is made of die-cast aluminum, a sufficient actual contact area can be ensured by a relatively easy manufacturing method, and an effective heat transfer effect can be obtained.

Note that although this embodiment has been described with reference to a case in which a clutch releasing means such as a foot operation and an engine starting means are included, this invention is also effective for embodiments that do not include these clutch releasing means and engine starting means. is clear from the above explanation. Further, the clutch housing includes the drive plate described in the above publication. Furthermore, this invention can also be applied to the centrifugal clutch shown in FIG. 1 in the above-mentioned publication.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a power transmission system showing an embodiment of this invention, and Figure 2 is a diagram showing the power transmission system shown in Fig.
3 is a sectional view along the line of FIG. 1 in a normal transmission state, and FIG. 4 is a sectional view showing the garter spring and the weight body inside it. 10...Clutch housing, 11, 23, 2
5...Clutch plate (11...Middle clutch plate, 23...Outermost clutch plate), 11a...Locking piece, 11a-1...Bulging part,
11a-2...adhering surface, 12...friction plate, 13...clutch hub, 15...means for variably controlling the pressing force of the laminate according to centrifugal force,
18...Side wall, 19...Outer peripheral wall, 22...Protrusion,
32...Friction material, 40...Recess, A...
Laminated body, a...Sliding surface.

Claims (1)

[Scope of utility model registration request] A clutch housing which is rotatably supported and has good thermal conductivity and is formed with an annular recess around the shaft; a clutch hub coaxially and rotatably housed in the recess of the clutch housing; and a clutch hub that is housed in the recess of the clutch housing and rotatably disposed within a plane orthogonal to the rotation axis; A plurality of clutch plates with good thermal conductivity each having locking pieces that are slidably locked in the axial direction on the protrusions of the clutch housing and projecting radially from the outer periphery, and a plurality of clutch plates that are interposed between these clutch plates. A plurality of friction plates rotatably disposed in a plane perpendicular to the rotation axis and slidably locked in the axial direction on the outer periphery of the clutch hub, and a laminated layer consisting of the clutch plate and the friction plate. A centrifugal clutch comprising means interposed between a clutch plate located at the outermost end of the clutch body and a side wall of the clutch housing, and variably controlling the pressing force of the laminated body in accordance with centrifugal force. , a friction material having high frictional resistance adhered to the friction plate, and a locking piece of the clutch plate interposed between the friction plates protruding in the axial direction, and the outer peripheral wall of the clutch housing and A thick bulge is formed with a contact surface that comes into close contact with the protrusion, and the heat generated by the sliding friction between the clutch plate and the friction plate is absorbed between the locking piece of the clutch plate and the clutch housing. A centrifugal clutch characterized in that it is configured to radiate heat from the outer peripheral wall and side wall of the clutch housing through the contact surface.