JP2008202685A - Torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent variation of set torque, and to prevent generation of a backlash in a rotation direction between a coil spring and an outer annular member by preventing relative rotation of a lid member with respect to the outer annular member. <P>SOLUTION: The torque limiter comprises the outer annular member 1, an inner ring 2 supported so as to be relatively rotatable to the outer annular member 1, the coil spring 3 attached to an outer periphery of the inner ring 2 with the tightening allowance, and the annular lid member 4 pressed in the outer annular member 1 and closing a gap between an inner periphery of the outer annular member 1 and the outer periphery of the inner ring 2. A supporting part 17 for supporting an end 12 of the coil spring 3 is provided on the outer annular member 1, a supporting part 19 for supporting the other end 13 is provided on the lid member 4, and torque transmitted between the inner ring 2 and the outer annular member 1 is restricted by slipping between the coil spring 3 and the inner ring 2. A protrusion 10 and a recession 11 engaged with each other and preventing rotation of the lid member 4 with respect to the outer annular member 1 are formed on an outer periphery of the lid member 4 and the inner periphery of the outer annular member 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spring-type torque limiter used in office machines such as printers and copying machines.

  As a spring-type torque limiter used in an office machine, an outer ring member, an inner ring supported so as to be relatively rotatable with respect to the outer ring member, a coil spring attached to the outer periphery of the inner ring with a tightening margin, An annular cover member that is press-fitted into the outer ring member and closes between the inner circumference of the outer ring member and the outer circumference of the inner ring, and a support portion that supports one end of the coil spring is provided on the outer ring member, and the other end There is known a structure in which a support portion for supporting a cover member is provided on a lid member (Patent Document 1).

  In the torque limiter, when the torque acting between the inner ring and the outer ring member is small, the coil spring rotates integrally with the inner ring by the tightening force of the coil spring against the inner ring, and one end of the coil spring is connected to the outer ring member or By pressing the support portion of the lid member in the circumferential direction, the outer ring member rotates integrally with the inner ring.

On the other hand, when the torque acting between the inner ring and the outer ring member is increased, the coil spring is torsionally deformed, and a diameter expanding action is generated in the coil spring. Therefore, the tightening force of the coil spring with respect to the inner ring becomes small, and slip occurs between the coil spring and the inner ring, and the torque transmitted between the inner ring and the outer ring member is limited by the slip. The amount of torque (hereinafter referred to as “set torque”) transmitted between the inner ring and the outer ring member in a state where slippage has occurred between the coil spring and the inner ring is the torque acting between the inner ring and the outer ring member. It is constant regardless of the size of the coil, and the size is determined by the tightening force of the coil spring against the inner ring.
JP 2006-10060 A

  The torque limiter prevents the lid member from rotating relative to the outer ring member by a frictional force generated between the outer circumference of the lid member and the inner circumference of the outer ring member. Therefore, when the lid member is press-fitted into the outer ring member when the torque limiter is assembled, or when the torque limiter is incorporated into an office machine, if the circumferential force acts on the lid member, the lid member is against the outer ring member. May cause relative rotation. In addition, when a torque is applied to the torque limiter incorporated in the office machine, the lid member may rotate relative to the outer ring member when one end of the coil spring presses the support portion of the lid member.

  When the lid member rotates relative to the outer ring member, when the lid member relatively rotates in the direction of pressing one end of the coil spring at its support portion, the coil spring twists and deforms to produce a diameter expansion action, The tightening force of the coil spring with respect to the inner ring changes due to the diameter expansion action, so that the set torque changes. On the other hand, when the lid member is relatively rotated in a direction in which the support portion is separated from one end of the coil spring, a backlash in the rotational direction is generated between the coil spring and the outer ring member, and between the outer ring member and the inner ring. There is a risk of delay in torque transmission.

  The problem to be solved by the present invention is to prevent the cover member from rotating relative to the outer ring member, thereby preventing a change in the set torque and rotating between the coil spring and the outer ring member. This is to prevent backlash in the direction.

  In order to solve the above-described problem, a convex portion and a concave portion that are engaged with each other to prevent the lid member from rotating with respect to the outer ring member are formed on the outer circumference of the lid member and the inner circumference of the outer ring member. In this case, since the lid member is prevented from rotating by the engagement between the concave portion and the convex portion, the lid member does not rotate relative to the outer ring member even when a circumferential force acts on the lid member.

  Furthermore, one of the convex portion and the concave portion is formed on the outer periphery of the lid member over the entire circumference at a constant interval in the circumferential direction, and the other of the convex portion and the concave portion is formed on the outer ring. It can be formed on the inner circumference of the member over the entire circumference with a certain interval in the circumferential direction. In this case, the position of the lid member with respect to the outer ring member can be shifted in the circumferential direction at every interval of the convex portion. Therefore, when coil springs having different circumferential positions at one end of the coil spring are selectively used. In addition, one type of lid member is sufficient.

  In the torque limiter according to the present invention, since the lid member does not rotate relative to the outer ring member, a change in the set torque can be prevented, and a backlash in the rotational direction is generated between the coil spring and the outer ring member. Can be prevented.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the torque limiter according to the embodiment of the present invention includes an outer ring member 1, an inner ring 2, a coil spring 3, and a lid member 4.

  The outer ring member 1 has a small inner diameter portion 5 and a large inner diameter portion 6 that is adjacent to the small inner diameter portion 5 in the axial direction and has a larger inner diameter than the small inner diameter portion 5. The small inner diameter portion 5 rotatably supports the inner ring 2 inserted coaxially in the outer ring member 1, and a coil spring 3 is interposed between the inner periphery of the large inner diameter portion 6 and the outer periphery of the inner ring 2. A cylindrical space 7 for housing is formed. An annular lid member 4 is press-fitted into the large inner diameter portion 6, and the gap between the inner circumference of the outer ring member 1 and the outer circumference of the inner ring 2 is closed by the lid member 4.

  As shown in FIG. 2, a ridge 8 that is continuous in the circumferential direction is formed on the outer periphery of the lid member 4, and is formed in an arc shape with a certain interval in the circumferential direction on both sides sandwiching the ridge 8 in the axial direction. The convex portion 10 is formed over the entire circumference. The protrusion 8 engages with an engaging groove 9 formed in the inner periphery of the large inner diameter portion 6 in the circumferential direction, and the lid member 4 is prevented from coming off from the outer ring member 1 by the engagement. The convex portion 10 engages with arc-shaped concave portions 11 formed on both sides sandwiching the engaging groove 9 of the large inner diameter portion 6 in the axial direction, and the lid member 4 rotates with respect to the outer ring member 1 by the engagement. It has been stopped.

  The coil spring 3 is a steel wire wound so as to have a single diameter. Further, the coil spring 3 is attached to the outer periphery of the inner ring 2 with a tightening margin, and due to the tightening margin, the tightening force of the coil spring 3 acts on the inner ring 2, so that when the inner ring 2 is rotated, the inner ring 2 Rotate with 2.

  The ends 12 and 13 of the coil spring 3 have a straight shape that is not bent with respect to the winding direction of the coil spring 3, and the end faces 14 and 15 of the steel wire constituting the coil spring 3 are in the length direction of the steel wire. The first end surface 14 is supported by a support portion 17 protruding from the inner end surface 16 of the small inner diameter portion 5, and the other end surface 15 is supported from the inner end surface 18 of the lid member 4. It is supported by. The support portion 17 extends over the entire radial width of the inner end surface 16, and the support portion 19 extends over the entire radial width of the inner end surface 18.

  The torque limiter configured as described above can be used as follows, for example.

  As shown in FIG. 1, the paper separating roller 20 of the office machine is attached to the end of the outer ring member 1, and the drive shaft 21 of the roller 20 is inserted into the inner ring 2. Next, the pin 22 erected on the drive shaft 21 is engaged with a notch 23 formed in the inner ring 2 so that the inner ring 2 rotates integrally with the drive shaft 21 by the engagement.

  In this state, when the drive shaft 21 is rotated in the winding direction of the coil spring 3 (direction a in FIG. 2) when the coil spring 3 is viewed from the lid member 4, the torque acting between the inner ring 2 and the outer ring member 1 is increased. When it is small, the coil spring 3 rotates integrally with the inner ring 2 by the tightening force of the coil spring 3 with respect to the inner ring 2, and the end surface 14 of the coil spring 3 presses the support portion 17 in the circumferential direction. Rotates integrally with the inner ring 2.

  On the other hand, when the torque acting between the inner ring 2 and the outer ring member 1 is increased, the coil spring 3 is torsionally deformed, and the coil spring 3 is expanded in diameter. Therefore, the tightening force of the coil spring 3 with respect to the inner ring 2 is reduced, and a slip occurs between the coil spring 3 and the inner ring 2, and the torque transmitted between the inner ring 2 and the outer ring member 1 is limited by the slip. The The torque transmitted from the inner ring 2 to the outer ring member 1 in a state where slippage occurs between the coil spring 3 and the inner ring 2, that is, the magnitude of the set torque is a torque acting between the inner ring 2 and the outer ring member 1. It is constant regardless of the size, and the size is determined based on the tightening force of the coil spring 3.

  When the drive shaft 21 is rotated in the direction opposite to the winding direction of the coil spring 3 when viewed from the lid member 4, the end surface 15 of the coil spring 3 presses the support portion 19, so that the outer ring member 1 is connected to the inner ring 2. Rotates together. At this time, similarly to the case where the drive shaft 21 is rotated in the winding direction of the coil spring 3, when the torque acting between the inner ring 2 and the outer ring member 1 is increased, the coil spring 3 is expanded in diameter. The torque transmitted between the inner ring 2 and the outer ring member 1 is limited.

  In this torque limiter, the lid member 4 is prevented from rotating around the outer ring member 1 by the engagement of the convex portion 10 and the concave portion 11, so that even if a circumferential force acts on the lid member 4, the lid member 4 does not rotate. It does not rotate relative to the member 1. Therefore, when the lid member 4 is press-fitted into the outer ring member 1 when the torque limiter is assembled, or when the torque limiter is incorporated into an office machine, the lid member 4 does not rotate relative to the outer ring member 1 and is set. Torque does not change. Further, since the lid member 4 does not rotate relative to the outer ring member 1 when torque is applied to the torque limiter incorporated in the office machine, the support portion 17 and the end surface 14, and the support portion 19 and the end surface 15 are respectively The backlash in the rotational direction does not occur between the coil spring 3 and the outer ring member 1.

  Further, in this torque limiter, since the convex portion 10 of the lid member 4 is formed on the entire circumference with a certain interval in the circumferential direction, the position of the lid member 4 with respect to the outer ring member 1 is set at every interval of the convex portion 10. Can be shifted in the direction. Therefore, a plurality of types of coil springs 3 whose end faces 14, 15 of the coil spring 3 are different from each other in the circumferential direction are prepared, and any one of the coil springs 3 is selected to provide a torque limiter having a required set torque. When configured, the position of the lid member 4 can be adjusted in the circumferential direction so that the end face 15 of the coil spring 3 can coincide with the support portion 19. In short, even when the coil spring 3 is selectively used, only one type of lid member 4 is sufficient.

  In the above embodiment, the convex portion 10 is formed on the outer periphery of the lid member 4, and the concave portion 11 is formed on the inner periphery of the outer ring member 1. A convex portion may be formed around the periphery, and the lid member 4 may be prevented from rotating with respect to the outer ring member 1 by engagement between the convex portion and the concave portion.

Sectional drawing of the torque limiter of embodiment of this invention 1 is an exploded perspective view of the torque limiter shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring member 2 Inner ring 3 Coil spring 4 Lid member 10 Convex part 11 Concave part 12 and 13 Ends 17 and 19 of coil spring Support part

Claims (2)

  An outer ring member (1), an inner ring (2) supported so as to be rotatable relative to the outer ring member (1), and a coil spring (3) mounted on the outer periphery of the inner ring (2) with a tightening margin And an annular lid member (4) that is press-fitted into the outer ring member (1) and closes between the inner periphery of the outer ring member (1) and the outer periphery of the inner ring (2), and the coil spring ( 3) provided with a support part (17) for supporting one end (12) of the outer ring member (1), and provided with a support part (19) for supporting the other end (13) of the lid member (4), In the torque limiter that restricts the torque transmitted between the inner ring (2) and the outer ring member (1) by slippage between the coil spring (3) and the inner ring (2), the lids are engaged with each other. The convex part (10) and the concave part (11) that prevent the member (4) from rotating with respect to the outer ring member (1) are connected to the outer periphery of the lid member (4). Torque limiter, characterized in that formed on the inner periphery of the ring member (1).   One of the convex portion (10) and the concave portion (11) is formed on the outer periphery of the lid member (4) over the entire circumference at a constant interval in the circumferential direction, and the convex portion (10) The torque limiter according to claim 1, wherein the other of the recesses (11) is formed on the inner circumference of the outer ring member (1) over the entire circumference at a constant interval in the circumferential direction.

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