JPH0374633A - Clutch - Google Patents

Abstract

PURPOSE:To obtain a small-sized clutch which can cope with the heavy-load work at a low cost by preventing the first clutch from being disengaged in the heavy-load work, and operating the second clutch to absorb the reaction at the time of locking. CONSTITUTION:When the load torque applied to an output shaft 5 is increased and made larger than the torque to start rotating a main clutch member 10 which is set by the coupling force applied between balls 12 excited by a spring 13 and irregular faces 11 of the main clutch member 10, the main clutch member 10 starts rotating by retreating balls 12 against the spring 13, an internal gear 20 starts rotating, the third-stage planetary reduction mechanism is run idly, and the output shaft 5 is disengaged. For the heavy-load work, the compression of the spring 13 is made maximum by an adjusting handle 6. The reaction of locking by the quick increase of load torque is absorbed by the rotation of the internal gear 20.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a clutch that is used in a power tool and operates as a torque limiter.

[Conventional technology]

In order to adjust the tightening torque in electric tools, a clutch is used that disconnects the drive section from the output section when the required tightening torque is reached. In a clutch that operates as such a torque limiter, in which a planetary reduction mechanism is used as a reduction gear, an uneven surface is formed on the internal gear of the planetary reduction mechanism, and the uneven surface is biased by a spring. Those equipped with engaging balls are often used. In the case of this clutch, if a torque greater than the engagement force between the ball and the uneven surface is applied, the internal gear will cause the ball to move backward against the spring bias and begin to rotate, which means that the planetary reduction mechanism will stop the ball from idling. By starting, the output part is disconnected, and the torque value for such disconnection can be determined by changing the spring force that biases the ball toward the uneven surface. Adjustment is possible by changing the engagement force between the ball and the uneven surface.

[Problem to be solved by the invention]

However, in the case of a clutch with the above structure, in order to increase the adjustable torque to a high level, the spring force must be considerably increased, making adjustment operations difficult and making it difficult to set a low level. Therefore, the spring force is usually set mainly at a low level, but when performing heavy load work, the power is not transmitted to the output section and the work becomes impossible. Here, a compression coil spring is used as the spring, and when the torque is adjusted in the direction of increasing the torque, the coil spring becomes tightly wound and loses its spring properties.In other words, the clutch There are some devices that can handle heavy loads by preventing disconnection, but in this case, if a load torque that exceeds the driving torque is applied and locks, it can cause a great deal of damage to the power transmission system members. There is a problem in terms of durability due to the load applied, and there is also a problem in safety since the lock reaction is applied to the operator. There are also clutches that increase the torque adjustment range by arranging two large and small springs in series, and electronic clutches that control the drive source by sensing changes in the motor's rotation speed and current value. Since the two springs are arranged in series, it inevitably becomes large, and the latter requires an electronic circuit and a sensor component, resulting in high costs. The present invention has been developed in view of these points, and its purpose is to provide a compact and low-cost device that can handle heavy load work while ensuring safety and durability when locked during use. There is a clutch that can be provided.

[Means to solve the problem]

Accordingly, the present invention provides a second main latch member whose negative surface is an uneven surface, a first clutch member formed as a ball that engages with the uneven surface of the main clutch member by receiving a spring bias,
a second clutch member having a tapered surface that contacts a tapered surface formed on a surface opposite to the uneven surface of the main clutch member; At the same time, the main clutch member and the second clutch member form a second clutch as a friction clutch, and the first clutch has a variable spring force that biases the ball. and a disabling means for disabling the spring, and the second clutch is characterized in that its slipping torque is greater than the maximum value in the adjustment range of the slipping torque of the first clutch. There is. [Operation] According to the present invention, the slip-start torque can be adjusted by the first clutch, and for heavy load work exceeding this adjustment range, the spring in the first clutch is disabled and w4.1 This can be countered by preventing the first clutch from disengaging, and when the first clutch is prevented from disengaging, the second clutch is activated. This allows the recoil to be absorbed. [Example] The present invention will be described in detail below based on an illustrated example. The illustrated example shows a member of a power transmission system in a power tool. First, the reducer placed between the motor 3 and the output shaft 5 will be explained. This is composed of a three-stage planetary reduction mechanism, and the first stage planetary reduction mechanism is the one for the motor 3. A pinion 31 attached to the output shaft, a carrier 32, an internal gear 34 fixed to the inner surface of the gear box 30, and a planetary gear 33 supported by a shaft 35 provided on the carrier 32 and meshing with the pinion 31 and the internal gear 34. The second stage planetary reduction mechanism consists of a pinion 36 integrally formed with the carrier 32, a carrier 37, an internal gear 39 fixed to the inner surface of the gearbox 30, and a pinion 36 provided on the carrier 37. It consists of a planetary gear 38 supported by a shaft 40 and meshing with a pinion 36 and an internal gear 39. The third stage planetary reduction mechanism includes a pinion 41 integrally provided with the carrier 37, a planetary gear 42 supported by a shaft 42 provided in the carrier portion at one end of the output shaft 5,
It is composed of internal gear 20,
A planetary gear 42 meshes with the binion 41 and the internal gear 20. The clutch is composed of a first clutch 1 and a second clutch 2. The first clutch 1 has an uneven surface 1 on the negative side.
1, a ring-shaped main clutch member 10, a steel ball 12 disposed in a hole formed in the gearbox 30, and a steel ball 12 arranged in a hole formed in the gearbox 30, with the ball 12 facing the uneven surface 11 of the main clutch member 10. Compression coil spring type spring 13 for urging
A thrust plate 14 is disposed between the spring 13 and the ball 12, and the spring receiver 15 is an adjustment mechanism that is rotatably attached to the tip of the gearbox 30. It is received by a step 60 on the inner surface of the handle 6. As shown in FIG. 3, the stepped portion 60 of the adjustment handle 6 is formed in a stepped shape.
When rotated, the spring receiver 15 moves in the axial direction, and the compression I of the spring 13 changes. The second clutch 2 is composed of the main clutch member 10 and the internal gear 20, and serves as a friction clutch in which the tapered surface of the inner peripheral surface of the main clutch member 10 and the tapered surface of the outer peripheral surface of the internal gear 20 are in contact with each other. The friction clutch is loaded by the spring 13 of the first clutch 1. The inclination angle α of the tapered surface of the second clutch 2 is set so that the starting torque thereof has a value suitable for heavy load work. Next, the operation will be explained. Internal gear 2 which is the second clutch member that constitutes the second clutch 2
0, the rotation of the motor 3 is normally blocked by both clutches 1.2, so the rotation of the motor 3 is transmitted to the output shaft 5 through the three-stage planetary reduction mechanism, causing the output shaft 5 to rotate. Then, the load torque applied to the output shaft 5 increases, and the ball 12, which is biased by the spring 13, and the main clutch member 1
If the engagement force acting between the main clutch member 10 and the uneven surface 11 at 0 becomes larger than the set torque that causes the main clutch member 10 to start rotating, the side surface of the convex portion on the uneven surface 11 of the main clutch member 10 will be as shown in FIG. Since the surface is inclined as shown in FIG. 4(a) and below the axis in FIG. 1, rotation is started by retracting the ball 12 against the spring 13. At this time, since the main clutch member 10 and the internal gear 20 are still connected, the internal gear 206 starts rotating. When the internal gear 20 starts rotating in this manner, the third stage planetary reduction mechanism idles, and the output shaft 5 is disconnected. The torque at which the main clutch member 10 begins to rotate (the sliding torque of the first clutch 1) is determined by rotating the adjustment handle 6 to change the amount of compression of the spring 13,
This can be adjusted by changing the engagement force. When performing heavy load work in which a load torque larger than the maximum torque obtained by the above adjustment is performed, the second
As shown in the figure and FIG. 5, the compression of the spring 13 by the adjustment handle 6 should be maximized. At this time, the spring 13 is in a tightly wound state and is no longer compressed. Since the main clutch member 10 no longer exhibits its original springiness, it is no longer possible to move the balls 12 backward and rotate. Therefore, it becomes possible to carry out work corresponding to heavy loads. However, when a load torque greater than the driving torque is applied during work, the internal gear 2o, which is the second clutch member, starts to slide against the main clutch member 1o against the frictional resistance between the main clutch member 10 and rotate. In order to interrupt power transmission to the output shaft 5, the locking reaction due to a sudden increase in load torque is absorbed by the rotation of this internal gear 20, and the reaction is not directly transmitted to the operator. Also, the load on the power transmission system members is small. 71st! In the embodiment shown in FIG. 1 and FIG. 8, the internal gear 20 is provided with a wedge-shaped protrusion whose both surfaces are tapered surfaces, and the main clutch member 10 is formed with a tapered groove in which the wedge-shaped protrusion is accommodated. The area of the contact surface between the main clutch member 10 and the internal gear 20 constituting the clutch 2 is increased to reduce the surface pressure acting on this contact surface. In selecting the material and shape of 10 and internal gear 20,
This allows for a wide range of designs, including room for cost reduction. Also, number 7! ! 1 shows a state in which the torque can be adjusted when the first clutch 1 is tightened, and FIG. 8 shows a state in which the first clutch 1 is fixed in a connected state.

【Effect of the invention】

As described above, in the present invention, the slip-start torque can be adjusted by the first clutch, and for heavy load work exceeding this adjustment range, the spring in the first clutch is disabled and the first clutch is This can be done by preventing the first clutch from being disengaged, and when the first clutch is prevented from being disengaged, the lock can be achieved by operating the second clutch. Since the second clutch can absorb the reaction, it is possible to ensure safety and durability against the lock reaction.Moreover, the second clutch is a friction clutch that shares the main clutch member with the first clutch. Because of this structure, it can be realized in a small size and at low cost.

[Brief explanation of drawings]

1 and 2 are longitudinal cross-sectional views of one embodiment of the present invention, FIG. 3 is an exploded perspective view of the same clutch portion, and FIG. 4(a)
b) and FIG. 5 are cross-sectional views illustrating the operation of the first clutch same as above, No. 651U is a front view showing the uneven surface and balls of the main clutch member, and FIGS. 7 and 8 are longitudinal cross-sectional views of other embodiments. 1 is a top view, 1 is a first clutch, 2 is a second clutch,
10 is a main clutch member, 12 is a ball, 13 is a spring, 2
0 indicates an internal gear.

Claims (1)

[Claims] (1) A main clutch member having an uneven surface on one side, a first clutch member formed as a ball that is spring-biased and engaged with the uneven surface of the main clutch member, and the uneven surface of the main clutch member. and a second clutch member having a tapered surface that contacts the tapered surface formed on the opposite side.
The main clutch member and the second clutch member form a second clutch as a friction clutch, and the first clutch is operated by the spring force of the spring that biases the balls. The clutch is variable, and is equipped with a disabling means for disabling the spring, and the second clutch has a slipping torque larger than the maximum value in the adjustment range of the slipping torque of the first clutch. Clutch.