JP2003065365A - Centrifugal clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal clutch having excellent performance of power transmission in spite of small size and capable of changing smoothly transmission characteristic. SOLUTION: The centrifugal clutch 1 comprising, a driven drum 2, a drive shaft portion 5 rotating around the center of a drum cylinder D inside the driven drum 2, and a clutch shoe 7 rotatably supported by the drive shaft portion 5 via pins 15 in a freely vibrating manner and extending by centrifugal force to contact with and slide on an internal peripheral surface 3 of the driven drum 2, wherein weights 16 extending by centrifugal force are rotatably supported by the drive shaft 5 via the pins 12 in an unrestrainedly vibrating manner, a resilient members 17, that apply force to the weights 16 in a direction to pull them inward, are provided between the weights 16 and the drive shaft portion 5, and the weights 16 are positioned so as to contact with an inside surface of the clutch shoe 7 to press the clutch shoe 7 against the internal peripheral surface 3 of the driven drum 2 when extending by centrifugal force.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an agricultural machine, a construction machine,
The present invention relates to a relatively small prime mover such as a light vehicle, a small boat, a pump, a wind-driven product, a compressor, an engine, an electric motor, a speed reducer, a transmission, and a centrifugal clutch used in a power transmission mechanism for rotating shaft torque.

[0002]

2. Description of the Related Art Generally, as a centrifugal clutch, a clutch shoe is swingably supported on a drive shaft portion that rotates in a driven drum, and a centrifugal force generated by the rotation of the drive shaft portion expands and swings the clutch shoe. Then, the clutch shoe that has expanded and oscillated is pressed against and slid on the driven drum, and the rotational driving force is transmitted by the frictional force at that time, and the cam mechanism for pressing the clutch shoe against the driven drum more strongly. The one provided between the section and the clutch shoe is known.

[0003]

Since the conventional centrifugal clutch as described above generates a sliding frictional force by the centrifugal force acting on the clutch shoe, in order to obtain a large sliding frictional force, the clutch shoe having a large mass is required. Or adopt
It is necessary to increase the rotation speed of the drive shaft. When increasing the mass of the clutch shoe, a large clutch shoe must be adopted, and there remains a problem that the entire clutch device becomes large or the weight increases.

In addition, even when a strong transmission torque is required, the entire centrifugal clutch must be increased in size, and the increased size of the centrifugal clutch interferes with peripheral parts, which makes mounting difficult. .

In a centrifugal clutch equipped with a cam mechanism, the transmission torque is suddenly increased when the cam is engaged in the groove and engaged with the clutch, so that the transmission characteristics cannot be changed smoothly, and the application is therefore difficult. It was sometimes limited.

The present invention has been made in view of the above-mentioned conventional problems, and provides a centrifugal clutch which is small in size, excellent in power transmission performance, and capable of smoothly changing transmission characteristics. With the goal.

[0007]

In order to achieve the above object, a centrifugal clutch according to the present invention has a driven drum, a drive shaft portion that rotates around the drum cylinder center in the driven drum, and a drive shaft portion that swings. In a centrifugal clutch having a clutch shoe which is rotatably supported by a shaft and which is opened by a centrifugal force and comes into sliding contact with an inner peripheral surface of a driven drum, a weight which is opened by a centrifugal force is rotatably supported by a drive shaft portion. At the same time, an elastic member for urging the weight in the closing direction is provided between the weight and the drive shaft portion, and the weight contacts the inner side surface of the clutch shoe when the weight is opened by the centrifugal force, so that the clutch shoe is in the driven drum. It is characterized in that it is provided at a position where it is pressed toward the peripheral surface.

Further, in the above construction, one of the features is that a mounting portion to which elastic members having the same or different elastic force can be detachably mounted is provided between the weight and the drive shaft portion.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic configuration diagram showing a centrifugal clutch according to an embodiment of the present invention, in which a part of a fixed plate is broken, FIG. 2 is a sectional view taken along the line EE in FIG. 1, and FIG.
4 is a schematic configuration diagram of the centrifugal clutch with the fixing plate removed, FIG. 4 is an external view of the centrifugal clutch of FIG. 3, and FIG. 5 is a component diagram showing a clutch shoe and a weight of the centrifugal clutch.

In each drawing, in a centrifugal clutch 1 according to this embodiment, a drive shaft portion 5 connected to a prime mover (not shown) is rotatable in a cylindrical driven drum 2 around a drum cylinder center D. It has been deployed. The drive shaft portion 5 is configured around the boss portion 6, and a disc-shaped fixing plate 9 is integrally fixed to the back surface of the boss portion 6. A disc-shaped fixing plate 11 is detachably attached to the front surface of the boss portion 6. Further, the boss portion 6 is formed with a shaft hole 4 into which a drive shaft such as a prime mover is fitted. That is, the drive shaft portion 5 is composed of the boss portion 6, the fixed plate 9, and the fixed plate 11. Driven drum 2
Is rotatably supported by a bearing of a clutch body (not shown).

The pin 15 pivotally supported by the fixed plate 9 in parallel with the drum cylinder D is attached to the shaft hole 2 of the clutch shoe 7.
By mounting 3 (see FIG. 5), the clutch shoe 7 is swingably supported on the drive shaft portion 5. A lining 8 as a friction material is fixed to the outer peripheral surface of the circular arc portion 7a of the clutch shoe 7. An accommodation space 22 is formed in the center of the clutch shoe 7 so as to penetrate therethrough in the front-rear direction. Similarly, by mounting the shaft hole 24 (see FIG. 5) of the weight 16 in the pin 12 axially supported by the fixed plate 9 in parallel with the drum cylinder center D, the weight 16 is moved to the drive shaft portion 5.
It is pivotally supported with respect to. An accommodation space 19 penetrating in the front-rear direction is also formed in the central portion of the weight 16.

The clutch shoes 7 are arranged one by one in diagonal positions with the drum cylinder center D as the center. Similarly, the weights 16 are also arranged one by one in diagonal positions with the drum cylinder center D as the center. In this case, the clutch shoes 7 and the weights 16 are alternately arranged in the circumferential direction of the drum to form a pair. The arrangement relationship between the pair of clutch shoes 7 and the weight 16 is such that, when the weight 16 is opened by centrifugal force, the outer surface 16b of the weight 16 contacts the inner surface 7b of the clutch shoe 7 so that the clutch shoe 7 is attached to the inner peripheral surface 3 of the drum. (In the direction of arrow K in FIG. 8), that is, in a position to press outward in the drum radial direction.

The fixing plate 9 is provided with projecting pieces at four locations on its peripheral portion, and these projecting pieces are bent in the drum cylinder center D direction to form bent parts 10, 10, 10, 10. Each of the bent portions 10 includes a corresponding one of the clutch shoes 7, 7 and the respective accommodation spaces 22 for the weights 16, 16 having the above-described arrangement.
It is housed in 19 respectively. That is, the fixed plate 9 and
The bending portion 10, the housing space 22, and the wall surface 22 a of the housing space 22 near the boss portion 6 constitute the mounting portion 21. Further, the mounting portion 18 is composed of the fixed plate 9, the bent portion 10, the housing space 19, and the wall surface 19 a of the housing space 19 near the boss portion 6.

With the fixing plate 11 removed, the elastic member 20 for the clutch shoe 7 is provided between the inner surface of the bent portion 10 of the mounting portion 21 and the wall surface 22a of the accommodation space 22.
Is detachably attached. Further, the elastic member 17 for the weight 16 is detachably mounted between the inner surface of the bent portion 10 of the mounting portion 18 and the wall surface 19a of the accommodation space 19. After the elastic members 20 and 17 are mounted in this manner, the fixing plate 11 is covered on the front surface of the boss portion 6 so that the mounting portion 2
1, 18 are capped. Then, the pins 15, 15, 12, 12 protruding from the fixing plate 11 are fixed by attaching a wave washer 13 and a retaining ring 14 to the respective tips.

For the elastic members 20 and 17, for example, coil springs are used, and they always urge the clutch shoe 7 and the weight 16 in the closing direction. When the drive shaft 5 reaches a predetermined rotation speed, the elastic member 20 has an elastic force that yields to the centrifugal force at that time and allows the clutch shoe 7 to open and close. The elastic member 17 is also made of a material having an elastic force that yields to the swinging movement of the weight 16 by bending due to the centrifugal force when the drive shaft portion 5 reaches a predetermined rotation speed.

In this embodiment, the weight 16
The elastic member 17 for the clutch is an elastic member 20 for the clutch shoe 7.
The one with higher elastic force is used. However, in the present invention, the magnitudes of the elastic forces of the weight elastic member and the clutch shoe elastic member are not particularly limited. Further, the predetermined rotation speed of the drive shaft portion 5 that can swing the clutch shoe 7 and the weight 16 toward the drum inner peripheral surface 3 is equal to the elastic member 2.
0 and the elastic member 17 may be the same or different.

The centrifugal clutch 1 of this embodiment is constructed as described above. Centrifugal clutch 1 having the above configuration
When the drive shaft portion 5 is stationary (see FIG. 1), the clutch shoe 7 is closed by the urging force of the elastic member 20. Therefore, as shown in FIG. 6, when the drive shaft portion 5 starts to rotate clockwise (in the direction of arrow R) in the figure, a centrifugal force outward in the drum radial direction corresponding to the rotation speed at that time is applied to the clutch shoe 7. , 7 and weights 16, 16 respectively. Then, when the rotational speed of the drive shaft portion 5 gradually increases and the centrifugal force at that time exceeds the biasing force of the elastic member 20, the clutch shoe 7 starts to open toward the drum inner peripheral surface 3.

When the rotational speed of the drive shaft portion 5 further increases, as shown in FIG. 7, the clutch shoe 7 swings toward the drum inner peripheral surface 3 (direction of arrow J), and the lining 8 rotates the drum inner peripheral surface. The surface 3 is brought into sliding contact and frictionally engaged. by this,
The rotational drive force from the drive shaft portion 5 is started to be transmitted to the driven drum 2 (solid line curve M in FIG. 9). In this case, since the elastic member 17 for the weight 16 has a higher elastic force than the elastic member 20 for the clutch shoe 7, the clutch shoe 7 starts swinging before the weight 16.

When the rotational speed of the drive shaft portion 5 is further increased, the weight 16 swings around the axis of the pin 12 toward the drum inner peripheral surface 3 as shown in FIG. ), The action point portion B1 of the outer surface 16b of the weight 16
Pushes up the force point portion A1 on the inner surface 7b of the clutch shoe 7 and further presses the lining 8 toward the drum inner peripheral surface 3 (point N in FIG. 9). As a result, the change state of the transmission torque (referred to as "transmission characteristic") depending on the rotation speed rises as shown by the solid curve O in FIG. 9, and the change in the transmission torque increases. Such a change in the transmission characteristic while the rotation speed of the drive shaft portion 5 increases is referred to as "mode change".

That is, the shaft center of the pin 12 is the fulcrum portion 12a.
Based on the lever principle, the portion of the circular arc portion 16a of the weight 16 on which the centrifugal force is most applied is the force point portion C1 (see FIG. 1), and the outer surface 16b of the weight 16 near the pin 12 is the action point portion B1. The pressing force from is doubled to generate a large transmission torque.

If the elastic member 17 of the mounting portion 18 is replaced with a member having a larger elastic force than that of the above embodiment, the mode change timing shifts to the point P in FIG. Changes to a curve Q (two-dot chain line). If the elastic force is exchanged with a larger elastic force, the point S changes like a curve T (two-dot chain line). On the contrary, it is also possible to replace the elastic member 17 with an elastic force smaller than that of the above-described embodiment. Thus, the elastic members 17 having different elastic forces
By exchanging with, the desired transfer characteristics can be obtained.

Alternatively, the elastic member 2 of the clutch shoe 7
Elastic member 17 of weight 16 having elastic force equivalent to 0
When the lining 8 is used, the weight 16 also swings when the lining 8 is in sliding contact with the drum inner peripheral surface 3 and frictionally engages, so that the weight 16 pushes up the clutch shoe 7 at a relatively low rotation speed and the inner peripheral surface of the drum. The lining 8 is further pressed to 3.

Incidentally, the solid curve Z in FIG. 9 shows the transfer characteristics of a conventional centrifugal clutch having only four clutch shoes without waiting for the cam mechanism or the weight 16 as in the present embodiment. However, the transmission torque monotonically increases as the rotation speed of the drive shaft 5 increases,
The transmission torque is smaller than the transmission characteristic (curve O) of the centrifugal clutch 1 after the mode change.

On the other hand, by changing the relative arrangement of the clutch shoe 7 and the weight 16 on the drive shaft portion 5 and the shape of the weight 16, the lever ratio (= (power point portion C1 and fulcrum portion 1
2a) / (distance between action point portion B1 and fulcrum portion 12a)) can be set to an arbitrary value, and a desired transfer characteristic can be selected. Alternatively, the transmission characteristic can be changed by changing the elastic force of the elastic member 20 for the clutch shoe 7.

Therefore, according to the centrifugal clutch 1, the weight 16 is swung by the centrifugal force of the rotary shaft portion 5 and the clutch shoe 7 is pushed up toward the drum inner peripheral surface 3 by the principle of leverage, so that the rotational speed is increased. A mode change occurs on the way to generate a large sliding friction force. Therefore, when trying to obtain the same transmission torque, a smaller one is provided. Further, since the structure is relatively simple mechanically, such as the combination of the clutch shoe and the weight, it can be manufactured at low cost. Then, by setting the elastic force of the elastic members 17 and 20 arbitrarily, a transmission characteristic as required can be obtained.

When the centrifugal clutch 1 is used in a go-kart, for example, the transmission characteristic of the engine driving force can be easily changed by replacing the centrifugal clutch 1 with an elastic member having an elastic force adapted to the difference in the characteristics of the driving lane and the driving characteristics of the individual. it can. Therefore, it is possible to drive according to one's taste.

In the above embodiment, an example in which two sets of clutch shoes 7 and weights 16 are provided in the driven drum 2 has been shown, but the present invention is not limited to this, and the driven drum is not limited to this. An appropriate number of sets of clutch shoes and weights may be provided within a structurally or functionally acceptable range of the internal space and the required sliding contact area of the lining.

Although an example in which the drive shaft portion 5 is rotationally driven in the clockwise direction (direction of arrow R in FIG. 1 and the like) has been shown above, in the centrifugal clutch 1, the drive shaft portion 5 is rotated counterclockwise ( It goes without saying that the same action and effect can be obtained even by rotating in the direction opposite to the arrow R).

[0029]

As described above in detail, according to the centrifugal clutch of the present invention, the rotational driving force is transmitted from the drive shaft portion to the driven drum by utilizing only the centrifugal force applied to the clutch shoe. And the transmission characteristic using the centrifugal force applied to the clutch shoe and the weight can be switched, so that the transmission characteristic can be changed smoothly without the sudden increase of the transmission torque unlike the conventional clutch using the cam mechanism. . And, by utilizing the centrifugal force applied to the clutch shoe and the weight, a higher transmission torque can be obtained as compared with the conventional clutch having no weight, so when manufacturing a centrifugal clutch of equivalent transmission capacity, it can be made smaller than the conventional one. It is possible to reduce the weight.

When the elastic member for the weight is provided with a replaceable mounting portion, the elastic member can be replaced with an elastic member having the same elastic force or a different elastic force, so that it is possible to change to a desired transmission characteristic. Therefore, it can be used in various applications depending on the required transfer characteristics.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a centrifugal clutch according to an embodiment of the present invention with a part of a fixed plate cut away.

FIG. 2 is a sectional view taken along line EE in FIG.

3 is a schematic configuration diagram of a state in which a fixing plate is removed from the centrifugal clutch of FIG.

FIG. 4 is an external view of the centrifugal clutch of FIG.

FIG. 5 is a component diagram showing a clutch shoe and a weight of the centrifugal clutch.

6 is an operation explanatory view of a portion of the centrifugal clutch shown in FIG.

7 is an operation explanatory view showing a state where the clutch shoe is opened from the state of FIG.

8 is an operation explanatory view showing a state where the weight is opened from the state of FIG. 7.

FIG. 9 is a graph showing power transmission characteristics of the present embodiment and the conventional centrifugal clutch.

[Explanation of symbols]

1 Centrifugal clutch 2 driven drum 3 Inner surface of drum 5 Drive shaft 7 Clutch shoe 7b Inside surface 8 lining 9 Fixed plate 10 Bent section 11 Fixed plate 12 pin 12a Support point 15 pin 16 weights 16a arc part 16b outer surface 17 Elastic member 18 Mounting part 19 accommodation space 19a wall surface B1 point of action C1 Power point D drum cylinder J arrow K arrow R arrow

Claims (2)

[Claims] 1. A driven drum, a drive shaft portion that rotates around a drum cylinder center in the driven drum, an inner peripheral surface of the driven drum that is swingably supported by the drive shaft portion, and is opened by centrifugal force. In a centrifugal clutch including a clutch shoe that is in sliding contact, a weight opened by a centrifugal force is swingably supported by a drive shaft portion, and an elastic member that biases the weight in a closing direction is provided between the weight and the drive shaft portion. The centrifugal clutch, wherein the weight is provided in a position that contacts the inner surface of the clutch shoe and presses the clutch shoe toward the inner peripheral surface of the driven drum when the weight is opened by centrifugal force. . 2. The centrifugal clutch according to claim 1, wherein a mounting portion to which elastic members having the same or different elastic force can be detachably mounted is provided between the weight and the drive shaft portion.