JPH0348371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spring clutch device used in a torque limiter or a paper feed mechanism of a copying machine.

Spring clutch devices are generally used in mechanisms that transmit rotation in one direction from the drive source side to the driven side, but do not need to transmit rotation in the opposite direction. 5 and 6 show a conventional example of this spring clutch device, which includes a drive gear 11 connected to the drive source side and a shaft rotatably inserted through the drive gear 11 and connected to the driven part side. 12
and a clutch spring 13 extrapolated to this shaft 12. The coil portion of the clutch spring 13 is fitted onto the shaft 12, and the hook portion 13a on one end side protrudes outward from the coil portion and engages with an engaging protrusion 11a protruding from one end surface of the drive gear 11. When the drive gear 11 rotates in the direction of arrow D, the hook portion 13a is pushed in the same direction, the diameter of the coil portion of the clutch spring 13 is reduced, and the shaft 12
rotation in the same direction is transmitted to.
On the other hand, when the drive gear 11 rotates in the direction of arrow C, the engagement between the hook portion 13a and the engagement protrusion 11a is released, so rotation is not transmitted in the same direction, resulting in one-way transmission of rotation. This is what we do. However, in such a conventional spring clutch device, the shaft 1 on the driven side
If an overload acts on the shaft 12 and the driven rotation stops even though power is being transmitted to the shaft 12, the hook portion 1 of the clutch spring 13
3a, and the hook portion 1
3a is damaged, which causes the spring clutch device to malfunction.

The present invention has been made in view of these drawbacks, and is designed to automatically cut off the transmission of rotational force by sliding the hook portion of the clutch spring when an overload is applied to the driven side.

Hereinafter, one embodiment of the present invention will be specifically described with reference to FIGS. 1 to 4.

In the present invention, the spring clutch device consists of a rotating cylindrical body 1, a shaft 2 rotatably inserted into the rotating cylindrical body 1, and a clutch spring 3 having a coil portion 3a fitted onto the shaft 2. . In this embodiment, the rotary cylindrical body 1 is formed by a gear formed in a bottomed cylindrical body, and the shaft 2 is inserted into the center hole, and an arc-shaped inner wall 4 is formed in the hollow inner wall 4. Projections 5, 5... are formed at four locations at 90 degree intervals.
In this embodiment, the clutch spring 3, in which the coil portion 3a is fitted onto the shaft 2, is a coil spring with a rectangular cross section, and the hook portion tip 3b at one end of the coil portion 3a is curved into an arc shape. At the same time, it extends outward from the coil portion 3a and comes into sliding contact with the inner wall 4 of the rotating cylindrical body 1. Therefore, the hook portion tip 3b is adapted to engage with the arcuate projections 5, 5, . . . as the rotating cylindrical body 1 rotates. In this case, the hook portion tip 3b and the protruding portions 5, 5
When an overload is applied, the engagement with the hook tip 3
The amount of protrusion of the protruding portion 5 or the amount of extension of the tip end 3b of the hook portion is appropriately set so that the portion b is bent and released.

In this embodiment configured in this way, the rotating cylindrical body 1 meshes with a gear (not shown) of a driving source, and the shaft 2 is connected to a driven part, so that the rotating cylindrical body on the driving side 1 rotates in the direction of arrow B in FIG. By tightening the spring 3, the shaft 2 rotates in the same direction. On the other hand, when the rotating cylindrical body 1 rotates in the direction of arrow A in FIG.
Since this direction of rotation is the direction in which the clutch spring 3 expands in diameter, no rotation is transmitted to the shaft 2. Therefore, rotation is transmitted in one direction, but if an overload is applied to the shaft 2 and a lock condition occurs while rotation is being transmitted from the rotating cylindrical body 1 on the driving side to the shaft 2 on the driven side. , the hook portion tip 3b of the clutch spring 3 is bent from the state shown by the chain line in FIG. 4 to the state shown by the solid line, so that the engagement between the hook portion tip 3b and the protrusion 5 is released. For this reason, the rotating cylindrical body 1 simply rotates idly, and no overload is applied to the hook portion tip 3b, thereby avoiding breakage of the hook portion tip 3b. When this locked state is released, the engagement between the hook portion tip 3b and the protruding portion 5 is restored again, and rotation in one direction is transmitted.

In the present invention, the same effect can be achieved even when the shaft 2 is on the driving side and the rotary cylindrical body 1 is on the driven side, so it is possible to prevent the tip end 3b of the hook portion from being damaged. Furthermore, the rotating cylindrical body 1 may be a cylindrical body instead of a cylindrical body with a bottom, a shaft body may be used instead of a gear, and the cross section of the clutch spring may be circular. Furthermore, the number of protrusions is not limited as long as the protrusions are formed in at least one location on the rotating cylindrical body.

According to the present invention described above, when an overload is applied to the driven side and a locked state occurs, the tip of the hook portion of the clutch spring is bent, and the hook portion tip engages with the protrusion of the rotating cylindrical body. Since the connection is released, there is an effect that damage to the tip of the hook portion can be prevented.

[Brief explanation of drawings]

1 and 2 are a front view and a sectional view of an embodiment of the present invention, FIGS. 3 and 4 are front views of the operating state, and FIGS. 5 and 6 are a front view and a sectional view of a conventional example. FIG. DESCRIPTION OF SYMBOLS 1... Rotating cylindrical body, 2... Shaft, 3... Clutch spring, 3a... Coil part, 3b... Hook part tip, 5... Projection part.

Claims (1)

[Claims] 1. A rotating cylindrical body having a protrusion formed on its inner wall, a shaft rotatably inserted into the rotating cylindrical body, a coil portion being externally inserted into the shaft, and a tip of a hook portion formed at the end of the coil portion being attached to the shaft. It consists of a clutch spring that is in sliding contact with the inner wall of a rotating cylindrical body, and one of the rotating cylindrical body or the shaft is set as a driving side and the other as a driven side, and by engagement of the protruding part and the tip of the hook part. In addition to transmitting the unidirectional rotation of the driving side to the driven side, the protrusion formed on the inner wall of the rotating cylindrical body prevents the engagement between the protrusion and the tip of the hook portion due to an increase in the load on the driven side. A spring clutch device characterized in that the spring clutch is formed with a protruding amount that is released by bending of the spring clutch and allows the drive side to idle.