JPH0666328A - Spring clutch device - Google Patents

Abstract

PURPOSE:To prevent the inner diameter of a spring from being expanded not to be returned to the original when a driven member is applied with the rotating force in the opposite direction. CONSTITUTION:A spring clutch device is provided with a rotation constraining means 31 constraining a driven member 17 from being rotated beyond an allowable quantity in the opposite direction to the rotation direction of a drive shaft 15 when the rotation of a ratchet member 13 is locked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring clutch device.

[0002]

2. Description of the Related Art A spring clutch device is a device for transmitting / disconnecting rotational power from a drive shaft to a driven member by utilizing a tightening force of a spring and is widely used as a feed device of a printer.

As shown in FIGS. 3 and 4, the conventional spring clutch device includes a clutch hub 11 and a spring 1.
2 and the ratchet member 13 are included.

The clutch hub 11 is fixed to the drive shaft 15 together with the drive pulley 16 via a spring pin 19.

Further, the spring 12 has an end portion 12a fixed to a follower pulley 17 as a follower member and an engaging portion 11a of the clutch hub 11 engaged with the other end portion 12b, which is engaged with the driven pulley 17, tightens with an elastic force to drive the drive shaft. It is formed so that the rotation of 15 can be transmitted to the driven pulley 17.

The ratchet member 13 is rotatably provided on the clutch hub 11 and is connected to the other end 12b of the spring 12. Then, the ratchet member 13 is rotationally locked from the rotation free state by a ratchet control means (not shown), and the tightening of the spring 12 with respect to the clutch hub 11 is released against the elastic force to slide the two (12, 11). It is formed so that it can be made.

However, when the drive shaft 15 is rotated in the direction of arrow E via the drive pulley 16 and the ratchet member 13 is made rotation-free by the ratchet control means in that state, the ratchet member 13 is synchronized with the drive shaft 15. And the rotational power of the drive shaft 15 is transmitted to the driven pulley 17 via the spring 12 (that is, the driven pulley 17 is rotated in the arrow E direction in synchronization with the drive shaft 15).

On the other hand, when the ratchet member 13 is rotationally locked by the ratchet control means, the ratchet member 1
The tightening of the spring 12 with respect to the clutch hub 11 is released by 3 against the elastic force, and both (12, 1
1) slides. As a result, the drive shaft 15 idles, and the rotation of the driven pulley 17 is stopped.

[0009]

In the spring clutch device described above, when the driven pulley 17 is mounted and adjusted while the ratchet member 13 is rotationally locked, the driven pulley 17 rotates in the rotational direction (E).
When the spring 12 is rotated in the direction opposite to the (direction), the inner diameter of the spring 12 is forcibly enlarged and cannot return to its original state.

When such a situation occurs, the ratchet member 1
3 is free to rotate, the clutch hub 11 is not sufficiently fastened to the spring 12 and the driven pulley 17
It becomes impossible to satisfactorily transmit rotational power.

In view of the above circumstances, an object of the present invention is to provide a spring clutch device capable of preventing the inner diameter of the spring from expanding even if a reverse rotational force acts on the driven member due to a malfunction or the like. is there.

[0012]

SUMMARY OF THE INVENTION A spring clutch device according to the present invention transmits power from a drive shaft to a driven member.
A spring clutch device for disconnecting, wherein an engaging portion of a clutch hub fixed to a drive shaft and an engaging portion of a clutch hub having one end fixed to a driven member and fitted in the other end is tightened by elastic force. A spring that transmits power from the drive shaft to the driven member, a ratchet member that is connected to the other end of the spring and is rotatably provided with respect to the clutch hub, and a clutch hub of the spring that locks the ratchet member in a rotation-free state. Ratchet control means that can release the tightening against the elastic force against the elastic force, and a rotation regulation that restricts the driven member from rotating beyond the allowable amount in the direction opposite to the rotation direction of the drive shaft when the ratchet member is rotationally locked. Means and are provided.

[0013]

According to the present invention having the above-described structure, when the ratchet member is rotationally locked and the rotational force in the direction opposite to the rotational direction of the drive shaft acts on the driven member due to a malfunction or the like, the driven member is rotated by the rotation regulating means. Is prevented from rotating in the opposite direction beyond the allowable amount. Therefore, the inner diameter of the spring is not forcibly enlarged and cannot be restored.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The spring clutch device according to the present embodiment is applied to a feed device of a printer, as shown in FIG.
As shown in (B), power is transmitted from the drive shaft 15 to the driven member (in the present embodiment, the driven pulley (7) is cut off. The drive shaft 15 has a drive pulley 16). Is rotated in the direction of arrow E, and a toothed belt (not shown) is hung on the driven pulley 17.

More specifically, as shown in FIGS. 1 and 2, the spring clutch device includes a clutch hub 11, a spring 12, a ratchet member 13, a ratchet control means 21, and a rotation restricting means 31. .

The same parts as those in FIGS. 3 and 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

Here, the ratchet control means 21 is formed so that the ratchet member 13 can be rotationally locked from the rotation-free state and the tightening of the spring 12 with respect to the clutch hub 11 can be released against the elastic force. In the present embodiment, the ratchet control means 21 separates the lever 22 that can be engaged with the teeth of the ratchet member 13 from the ratchet member 13 against the elastic force of the spring 23, as shown in FIG. And an electromagnet 24 for

However, when the electromagnet 24 is excited, the lever 22 rotates clockwise in FIG. 2 to be positioned at the position shown by the chain double-dashed line in the figure, and the rotation lock state of the ratchet member 13 is released to free it. It becomes a state. When the electromagnet 24 is demagnetized, the lever 22 is returned to the position shown by the solid line in the figure by the elastic force of the spring 23, and the rotation of the ratchet member 13 is locked.

The rotation restricting means 31 is a driven member (driven pulley 17) when the ratchet member 13 is rotationally locked.
Is a means for restricting rotation of the drive shaft 15 in a direction opposite to the rotation direction (E direction) beyond the allowable amount. In this embodiment, the rotation restricting means 31 has a predetermined number (three) of engaging grooves 37, 37, 37 provided on the driven pulley 17 side and a predetermined number of (engaging) provided on the ratchet member 13 side. Groove 3
(7, 37, 37 and the same number) rotation restriction protrusions 33, 33, 3
3 and 3. An engaging inner surface portion 13a having an inner diameter larger than that of the other portions is formed on the inner surface of the ratchet member 13 at the right side portion in FIG. 1 (A).

An engaging ring portion 17a is provided on the left end portion of the driven pulley 17 in the figure so as to project toward the ratchet member 13, and most of the engaging ring portion 17a is of the ratchet member 13. The engagement inner surface portion 13a is fitted so as to be relatively rotatable.

More specifically, the above-mentioned engaging grooves 37, 3
7, 37 are attached to the engaging ring portion 17a of the driven pulley 17
It is formed at a pitch of 20 °. Also, the rotation restricting protrusion 3
3, 33, 33 are formed in the engaging inner surface portion 13a of the ratchet member 13 corresponding to the engaging grooves 37, 37, 37, and rotate in the engaging grooves 37, 37, 37 within a predetermined angle range. It is inserted so that it can move. Here, each engagement groove 37 and each rotation restricting protrusion 33 is formed by the spring 12
The ratchet member 13 and the driven pulley 17 are allowed to rotate relative to each other when the clutch hub 11 is tightened and unfastened, but the driven pulley 17 causes the ratchet member 13 to rotate.
On the other hand, the size and the like are selected so that the drive shaft 15 can be restrained from rotating beyond the allowable amount in the direction opposite to the rotation direction (E direction). Here, the “allowable amount” means each end portion 12
a and 12b are driven pulley 17 and ratchet member 1
The spring 12 connected to the driven pulley 17 has a larger inner diameter as the driven pulley 17 rotates in the reverse direction.
If is free of rotation, it means the amount of rotation that returns to the original inner diameter.

Next, the operation will be described. In the state where the ratchet member 13 is rotationally locked by the ratchet control means 21, even if a rotational force in a direction opposite to the rotational direction (E direction) of the drive shaft 15 acts on the driven pulley 17 due to a malfunction or the like, the rotation regulating means. By the cooperation of the rotation restricting protrusions 33 of 31 and the engaging grooves 37, the driven pulley 17 is prevented from rotating in the opposite direction beyond the allowable amount. Therefore, the inner diameter of the spring 12 will not be forcibly enlarged and will not return to the original inner diameter.

However, according to this embodiment, when the ratchet member 13 is rotationally locked, the driven pulley 17 is restricted from rotating in a direction opposite to the rotational direction (E direction) of the drive shaft 15 beyond the allowable amount. Since the rotation restricting means 31 is provided, it is possible to prevent the inner diameter of the spring 12 from expanding and being unable to return to its original position even if a reverse rotational force acts on the driven pulley 17 due to a malfunction or the like. it can. Also, vibration during operation can be suppressed.

[0024]

According to the present invention, there is provided a rotation restricting means for restricting the follower member from rotating beyond the allowable amount in the direction opposite to the rotation direction of the drive shaft when the ratchet member is rotationally locked. Therefore, it is possible to prevent the spring from being unable to return to its original state due to the enlargement of the inner diameter even if a rotational force in the opposite direction acts on the driven member due to a malfunction or the like.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram for explaining a ratchet control means of one embodiment.

FIG. 3 is an exploded perspective view for explaining a schematic configuration of a conventional spring clutch device.

FIG. 4 is a cross-sectional view for explaining a schematic configuration of a conventional spring clutch device.

[Explanation of symbols]

 11 clutch hub 12 spring 13 ratchet member 15 drive shaft 17 driven pulley (driven member) 21 ratchet control means 31 rotation restricting means

Claims (1)

[Claims] 1. A spring clutch device for transmitting / disconnecting power from a drive shaft to a driven member, comprising: a clutch hub fixed to the drive shaft; and one end portion fixed to the driven member and fitted to the other end portion. A spring that tightens the engaged portion of the engaged clutch hub with elastic force to transmit power from the drive shaft to the driven member, and a ratchet member that is connected to the other end of the spring and is rotatably provided with respect to the clutch hub. And ratchet control means that can lock the ratchet member from the rotation free state to release the tightening of the spring against the clutch hub against the elastic force, and the driven member in the direction opposite to the rotation direction of the drive shaft when the ratchet member is rotation locked. A spring clutch device, comprising: a rotation restricting means for restricting the rotation exceeding an allowable amount.