JP4467502B2 - Torque limiter - Google Patents

Description

  The present invention relates to a spring-type torque limiter used in office machines such as printers and copying machines, and more particularly to measures for preventing the occurrence of vibrations or abnormal noises in coil springs.

  As shown in FIG. 5, a conventionally known spring-type torque limiter used for an office machine or the like is relatively rotatable at an outer ring member 41 and a boss portion 42 at one end inserted therein. A supported inner ring 43, a coil spring 44 attached to the outer diameter surface of the inner ring 43 with a required tightening allowance, and an outer ring member 41 fitted and fixed to the inner diameter surface of the other end of the outer ring member 41. It comprises a lid member 49 that closes the radial surface and rotatably supports the inner ring 43. The coil spring 44 has a large-diameter portion 44a and a small-diameter portion 44b, and the small-diameter portion 44b is tightly bound to the outer-diameter surface of the inner ring 43 with a required tightening allowance. A hook 45 bent in the axial direction is provided at the end of the small-diameter portion 44b, and is engaged with the boss portion 42 of the outer ring member 41. A hook 46 bent in the axial direction is also provided at the end of the large-diameter portion 44a, and is engaged with a lid member 49 (see Patent Document 1).

  In the torque limiter 40 described above, the coil spring 44 is wound in the same direction of rotation (in the illustrated case, right-handed) by the relative rotation of the inner ring 43 and the outer ring member 41 and in the same rotational direction (in the illustrated case, the hook 45). When rotating in the clockwise direction when viewed from the side, a diameter expanding action occurs in the small diameter portion 44b, and a constant magnitude torque, that is, a specified torque value is generated. When relative rotation occurs in the opposite direction, a diameter reducing action occurs in the small diameter portion 44b and the inner ring 43 is locked. In this case, the function as a torque limiter cannot be achieved. That is, it acts as a one-way torque limiter.

  However, in the torque limiter, in the initial stage of torque generation due to the relative rotation of the inner ring 43 and the outer ring member 41, a partial deflection 52 occurs in the vicinity of the hook 45 of the coil spring 44 (see FIG. 6) and disappears. Thus, the inner ring 43 or the outer ring member 41 cannot rotate until the entire small diameter portion 44b is expanded. That is, there is a problem that a time delay, that is, a backlash occurs between the input of the rotational force and the torque generation, and the timing of torque transmission is shifted.

  On the other hand, the coil spring 44 of the torque limiter has a large-diameter portion 44a, and the hooks 45 and 46 bent in the axial direction at both ends prevent the torque limiter from being downsized. At the time of assembly, it is necessary to insert the hook over the engagement hole of the outer ring member or the like, which also becomes a factor that hinders workability.

  In order to solve these problems, as shown in FIGS. 7 (a) and 7 (b), a coil spring having a single diameter is used, and both ends thereof are cut while retaining the coil shape. (Referred to as straight end portions 45 ′ and 46 ′), and the end portions 45 ′ and 46 ′ are respectively formed on the outer ring member protrusion 53 and the lid member 49 provided on the inner diameter surface of the outer ring member 41. The structure (refer FIG.7 (b)) which abuts on the side surface of the provided lid member protrusion 54 can be considered.

  However, when such a coil spring 44 is attached to the inner ring 43 with a certain tightening margin, as shown in FIG. 8, the coil portion 56 is slightly enlarged to increase the radius of curvature, but the straight end 45 ' A portion in the vicinity thereof is wound around the inner ring 43 while being curved while maintaining a curvature radius in a free state smaller than the curvature radius of the coil portion 56, and its tip abuts against the outer diameter surface of the inner ring 43. Causes a problem that causes interference. The same phenomenon occurs in the other straight end 46 '.

  In order to solve the above problems, the present applicant has applied for a patent for an improved torque limiter in which the coil spring 44 is improved (Japanese Patent Application Nos. 2004-362804 and 2005-36352). As shown in FIGS. 9A to 9C, the coil spring 44 used in this improved torque limiter has arc portions 57 and 58 having a radius of curvature larger than the other coil portions 56 in the free state in the vicinity of both ends. In the state where the coil spring 44 is expanded and attached to the inner ring 43 with a required tightening margin (see the one-dot chain line in FIG. 9B, see FIG. 9C). The size is set to be substantially equal to the radius of curvature of the portion 56, and three restricting protrusions 59 are provided on one or both of the inner diameter surface of the outer ring member 41 and the lid member 49.

In the improved torque limiter, the front end surfaces 57 ′ and 58 ′ of the arc portions 57 and 58 are provided on the side surfaces of the outer ring member protrusion (not shown) and the lid member protrusion 54 without providing hooks at both ends. Suitable for miniaturization because of the butted shape. Further, since the circular arc portions 57 and 58 are provided, it is possible to prevent the front end surfaces 57 ′ and 58 ′ from interfering with the inner ring 43. The effect that generation | occurrence | production can also be suppressed is produced.
JP-A-8-270673 ("Example", FIGS. 1 and 2)

  By the way, in the spring-type torque limiter, vibration is generated in the coil spring due to the variation of the friction coefficient of the sliding surface between the coil spring and the inner ring, and the vibration is amplified by the coil spring, causing abnormal noise. There is a case. In particular, at low speed rotation, it is difficult to form an oil film. Such abnormal noise becomes unpleasant noise for the user of the office machine. Although there is a method of stabilizing the coefficient of friction and suppressing vibration by a lubrication method, in recent years, so-called chemical attack is regarded as a problem, and since it is limited by additives that can be added to base oil, it can not be a sufficient measure . For this reason, it is necessary to take measures to prevent the occurrence of vibrations and abnormal noises by a mechanical method.

  On the other hand, the improved torque limiter according to the above-mentioned patent application can achieve the intended purpose, but the front end surfaces 57 ′ and 58 ′ of the arc portions 57 and 58 provided at both ends of the coil spring 44 are removed. Since the ring member protrusion (not shown) and the structure are merely abutted against the side surface of the lid member protrusion 54, the arc portions 57 and 58 have insufficient rigidity. For this reason, as shown in FIG. 9C, when the inner ring 43 rotates in the counterclockwise direction A, the tip surface 57 ′ of the arc portion 57 is pressed against the lid member protrusion 54 for the arc portion 57, At this time, the force indicated by the arrow F acts and the arc portion 57 is pushed outward (see the one-dot chain line in FIG. 9C). For this reason, the rigidity of the circular arc part 57 is lowered, and the vibration of the sliding part is transmitted to this part, which causes abnormal noise. The same phenomenon occurs on the arc portion 58 side.

  Accordingly, an object of the present invention is to provide a torque limiter that suppresses the generation of vibration and noise by increasing the rigidity of the coil spring end portion in the improved torque limiter.

  In order to solve the above-mentioned problem, as shown in FIG. 1, the present invention includes an outer ring member 1, an inner ring 2 inserted into the inner ring member 1 and supported so as to be relatively rotatable at a boss portion 5 at one end, The coil spring 4 attached to the outer diameter surface of the inner ring 2 with a required tightening margin and the other end portion of the outer ring member 1 are fitted and fixed to the inner diameter surface to close the outer diameter surface of the inner ring 2. It comprises a lid member 3, and one end of the coil spring 4 is engaged with the outer ring member projection 12 and the other end is engaged with the lid member projection 18, so that the inner ring 2 and the outer ring member 1 rotate relative to each other. The following configuration is adopted as a prerequisite for a torque limiter that generates a predetermined torque by a diameter expanding action generated in the coil spring 4.

  That is, as shown in FIGS. 4 (a) and 4 (b), arc-shaped arc portions 33, 34 having a radius of curvature larger than that of the coil portion 4a in a free state in the vicinity of each end including both ends of the coil spring 4. And the radius of curvature of the coil spring 4 is substantially the same as the radius of curvature of the coil portion 4a when the coil spring 4 is expanded and attached to the inner ring 2 with a required tightening allowance. Is set.

  Further, as shown in FIGS. 3A and 3B, the side surfaces 12 a and 18 a of the outer ring member protrusion 12 and the lid member protrusion 18 are in relation to the radial reference line L <b> 1 of the outer ring member 1. A configuration is adopted in which the tip surfaces 33 'and 34' of the arc portions 33 and 34 are abutted between the inclined side surfaces 12a and 18a and the inner ring 2 at a predetermined angle θ.

  In the torque limiter having the above-described configuration, the front end surfaces 33 ′ and 34 ′ of the arc portions 33 and 34 at both ends of the coil spring 4 are abutted against the side surfaces 12a and 18a having an angle θ, respectively, and force F in the inner diameter direction (FIG. 3 ( d), the movement in the outer diameter direction is restricted. Thereby, the rigidity of the circular arc portions 33 and 34 at both ends is increased, and the occurrence of vibration and abnormal noise is suppressed.

  As described above, the torque limiter according to the present invention has an effect of suppressing the generation of vibration and the generation of abnormal noise due to the vibration because the rigidity of the arc portions 33 and 34 at both ends of the coil spring 4 is increased. Since the mechanical structure increases rigidity, there is no concern about chemical attack, and vibration and abnormal noise during low-speed rotation are solved. It can be set low and reliable paper separation can be performed. Moreover, since generation | occurrence | production of noise can be suppressed, it does not give a user a discomfort.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 to 3, the torque limiter 10 of the embodiment includes an outer ring member 1, an inner ring 2, an annular lid member 3, and a coil spring 4 as in the conventional case. A boss portion 5 is provided at one end of the outer ring member 1, and an inner diameter surface 6 larger in diameter than the coil spring 4 is formed from the boss portion 5 to the open end of the other end. A shaft insertion hole 7 is provided at the center of the boss portion 5, and an inner ring support portion 8 having a larger diameter is provided inside the shaft insertion hole 7.

  An outer ring member protrusion 12 (see FIG. 3A) is provided on a part of the boss portion inner end surface 11 that forms a step portion between the inner ring support portion 8 and the inner diameter surface 6. The outer ring member protrusion 12 is set to have a size over the entire radial width of the boss portion inner end surface 11 and approaches the outer diameter surface of the inner ring 2. Further, the height (the length in the axial direction) is formed slightly larger than the cross-sectional size of the wire constituting the coil spring 4, the tip end surface 33 ′ of the coil spring 4 can abut, and the coil spring 4 The second round portion is formed in a size that does not interfere.

  The outer ring member protrusion 12 has two side surfaces in the axial direction, of which the side surface 12a (see FIG. 3A) on which the tip end surface 33 'of the coil spring 4 abuts is the outer ring member 1. Inclined toward the radial reference line L1 passing through the center O by a certain inclination angle θ toward the tip surface 33 ′. The inclination angle θ is set to an angle sufficient to prevent the distal end surface 33 ′ of the coil spring 4 from being engaged between the side surface 12 a and the inner ring 2 and preventing radial movement.

  A circumferential engagement groove 13 is provided in a portion near the open end of the inner diameter surface 6. Further, an engagement protrusion 14 for a roller or the like is provided on the outer surface of the end portion on the boss portion 5 side.

  In the inner diameter surface 6 of the outer ring member 1, there are three restricting projections 28 in the circumferential direction over the range of about half of the inner diameter surface 6 from the inner end surface 11 of the boss portion toward the open end surface side of the outer ring member 1. Is provided. The circumferential interval between the restricting protrusions 28 is about a quarter of the entire circumference including the outer ring member protrusion 12. The inner end face 29 of each restricting protrusion 28 is tapered so that the tip side has a large diameter. Further, as shown in FIGS. 3A and 3C, the inner surface of each regulating projection 28 has a radius R (R = the radius of the inner ring 2 + the width of the coil spring 4 + δ, where δ is a coil spring. 4 and the gap between the restricting protrusions 28).

  The inner ring 2 has an inner diameter surface that is concentric with the shaft insertion hole 7, and the coil spring 4 is attached to the outer diameter surface with a required tightening allowance. One end portion of the inner ring 2 is rotatably fitted and supported at the inner ring support portion 8 of the boss portion 5, and the other end portion projects outward from the outer ring member 1. The lid member 3 is fitted to the outer diameter surface of the protruding end. An engagement recess 15 with a pin standing on a shaft (not shown) is provided at an end of the inner ring 2 protruding from the lid member 3.

  An engagement rib 16 is formed on the outer diameter surface of the lid member 3, and the engagement rib 16 is fitted into the engagement groove 13. The lid member 3 closes the space between the inner diameter surface of the outer ring member 1 and the outer diameter surface of the inner ring 2, and the inner ring 2 is rotatably supported. The lid member 3 is firmly fitted to the outer ring member 1, but the fitting strength is obtained when a required tool is inserted into a pair of holes 17 provided on the outer surface of the lid member 3 and rotated. The outer ring member 1 can rotate with respect to the outer ring member 1.

  Further, a lid member protrusion 18 (see FIGS. 2 and 3B) is provided on the inner surface of the lid member 3. The height (axial length) of the lid member protrusion 18 is formed to be slightly larger than the size of the cross section of the wire constituting the coil spring 4, and the tip surface 34 'of the coil spring 4 can be brought into contact therewith. However, it is set so as not to interfere with the second round portion of the coil spring 4. Further, the height in the radial direction is set so as to approach the outer diameter surface of the inner ring 2.

  As shown in FIG. 3B, the lid member protrusion 18 has two axial side surfaces, of which the side surface 18a on which the other tip surface 34 'of the coil spring 4 abuts is outside. The tip end surface 34 'is inclined with respect to a reference line L1 in the radial direction passing through the center O of the ring member 1 by a certain inclination angle θ. The inclination angle θ is set to an angle sufficient to allow the distal end surface 34 ′ of the coil spring 4 to be engaged between the side surface 18 a and the inner ring 2 and prevent radial movement.

  In addition, on the inner surface of the lid member 3, restricting protrusions 31 having a length that is approximately half the axial length of the inner diameter surface 6 of the outer ring member 1 are provided at three locations in the circumferential direction. The interval in the circumferential direction of the restricting protrusion 31 is about a quarter of the entire circumference including the lid member protrusion 18. The inner end surface 32 of each restricting protrusion 31 is tapered so that the tip side has a small diameter. The inner surface of each restricting protrusion 31 is formed as an arc surface belonging to an inscribed circle having the same radius R as that of the restricting protrusion 28 (see FIGS. 3B and 3C).

  As shown in FIG. 2 and FIG. 4A, the coil spring 4 is a steel wire (in the illustrated case, a square wire but may be a round wire) is wound as many times as necessary so as to have a single diameter. Is. In the free state before being attached to the inner ring 2, both end portions are basically straight end portions, but in this case, in the range of about one-half turn from the end portion, it has a larger radius of curvature than the other coil portions. Arc portions 33 and 34 are formed (see FIG. 4A). Since the inner diameters of the coil portions 4a other than the arc portions 33 and 34 are formed slightly smaller than the outer diameter of the inner ring 2, when they are fitted to the inner ring 2, they are mounted with a certain tightening allowance.

  When the coil spring 4 is attached to the inner ring 2 with a certain tightening margin, the coil spring 4 is slightly enlarged in diameter and has a larger radius of curvature, which is substantially equal to the radius of curvature of the arc portions 33 and 34 (see FIG. 4A). Chain line, see FIG. 4 (b)). In other words, the initial (natural) radius of curvature of each arc portion 33, 34 is set to a size that is substantially equal to the radius of curvature of the coil portion 4 a in the state of being attached to the inner ring 2. By providing such arc portions 33 and 34 at both ends of the coil spring 4, interference between the tip surfaces 33 'and 34' and the inner ring 2 is eliminated.

  The inner ring 2 fitted with the coil spring 4 as described above is assembled into the outer ring member 1 and the lid member 3 is fitted. In this state, the two end surfaces 33 ′ and 34 ′ of the coil spring 4 are not necessarily engaged with the side surfaces 12 a and 18 a of the outer ring member protrusion 12 and the lid member protrusion 18, respectively. In order to achieve the engagement, the outer ring member 1 and the inner ring 2 are fixed, and a required tool is inserted into the hole 17 of the lid member 3 and rotated in the winding direction of the coil spring 4. During the rotation, one end surface 34 ′ of the coil spring 4 hits the side surface 18 a of the lid member protrusion 18 and abuts on the side surface 18 a having the inclination angle θ (see FIG. 3B). Further, when a force that overcomes the tightening force of the coil spring 4 is applied and rotated, the other tip surface 33 ′ is abutted against the side surface 12a having the inclination angle θ of the outer ring member protrusion 12 (see FIG. 3A). ). Thereby, both front end surfaces 33 ′ and 34 ′ of the coil spring 4 are engaged with the outer ring member protrusion 12 and the cover member protrusion 18 without any gaps in the circumferential direction, and at the same time, due to the presence of the inclined side surfaces 18 a and 12 a. Movement in the radial direction is restricted.

  In this assembled state, the inner surface of the restriction projection 28 of the outer ring member 1 and the inner surface of the restriction projection 31 of the lid member 3 are fixed over the entire length of the outer diameter surface of the coil spring 4. They are opposed with a regulation gap δ (see FIG. 3C).

  The restriction gap δ is set to 0.1 mm ≦ δ ≦ 0.3 mm, preferably δ = 0.2 mm in consideration of a tolerance range at the time of manufacturing a resin part.

  The torque limiter according to the embodiment is configured as described above, and, as in the conventional case, torque is generated in accordance with the diameter expansion action of the coil spring 4 due to the relative rotation of the outer ring member 1 and the inner ring 2, but the initial generation of the torque. The deflection (refer to reference numeral 52 in FIG. 6) that has conventionally occurred in the coil end of the coil 52 is controlled by the inner diameter surface of the restricting protrusions 28 and 31 serving as a restricting surface to restrict the bulging of the coil end. Occurrence is suppressed. For this reason, the backlash does not occur at the initial stage of torque generation, the diameter expansion action of the coil spring 4 occurs, and the torque is immediately generated without time delay.

  Further, since the arcuate portions 33 and 34 are formed in advance on the both end surfaces 33 ′ and 34 ′ of the coil spring 4, it does not interfere with the outer diameter surface of the inner ring 2 and the generation of local pressure can be avoided. ing.

  Further, the force relationship on the side surface 12a (the same applies to the side surface 18a) is as shown in FIG. That is, in the figure, F1 is a tangential force of the tip surface 33 ', F2 is a drag force from the side surface 12a, and F is a combined force thereof. The tip surface 33 ′ receives an inward force due to the combined force F. Thereby, the rigidity of the arc portions 33 and 34 of the coil spring 4 is enhanced.

  The restriction protrusions 28 and 31 are provided so as to form a restriction surface over the entire length of the coil spring 4, but these restriction protrusions are provided only at a portion corresponding to the end of the coil spring 4. If this is provided, the above-described bending occurs behind the regulating protrusion, and the generation of the bending cannot be effectively prevented. After all, it is necessary to provide the regulation protrusions 28 and 31 over the entire length. Note that it is possible to adopt a configuration in which only one of the restricting protrusions 28 and 31 is provided and the axial length thereof is set to reach the entire length of the coil spring 4.

  Further, as another means for preventing the bending of the coil spring 4 in the initial stage of torque generation, the entire inner diameter surface of the outer ring member 1 is replaced with the means for forming the restriction surface by the restriction protrusions 28 and 31. A similar effect can be obtained also by using a restricting surface having a diameter having a restricting clearance δ.

Cross-sectional view of the embodiment Exploded perspective view (A) is a sectional view taken along line AA in FIG. 1, (b) is a sectional view taken along line BB, (c) is a partially enlarged sectional view of (a), and (d) is an explanation of force relations. Figure (A) Front view of natural state of coil spring, (b) is a sectional view of the coil spring mounted state Sectional view of a conventional torque limiter Sectional view taken along line XX in FIG. (A) Sectional view of another conventional example, (b) Perspective view of coil portion of (a) Cross-sectional view for explaining the problem of the conventional example (A) Perspective view of coil spring of torque limiter according to prior application, (b) Enlarged end view, (c) Cross-sectional view of mounted state

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring member 2 Inner ring 3 Cover member 4 Coil spring 4a Coil part 5 Boss part 6 Inner diameter surface 7 Shaft insertion hole 8 Inner ring support part 10 Torque limiter 11 Boss part inner end surface 12 Outer ring member protrusion 13 Engagement groove 14 Engagement protrusion 15 Engaging recess 16 Engaging rib 17 Hole 18 Lid member protrusion 28 Restriction protrusion 29 Inner end face 31 Restriction protrusion 32 Inner end face 33 Arc part 34 Arc part 33 'End face 34' End face

Claims (3)

An outer ring member (1), an inner ring (2) inserted into the inner ring (1) and supported at a boss portion (5) at one end so as to be relatively rotatable, and attached to the outer diameter surface of the inner ring (2) with a required tightening allowance The coil spring (4) and a lid member (3) that is fitted and fixed to the inner surface of the outer ring member (1) at the other end of the outer ring member (1) to close the outer ring surface of the inner ring. One end of the spring (4) is engaged with the outer ring member (1) and the other end is engaged with the lid member (3), so that the inner ring (2) and the outer ring member (1) rotate relative to each other. In the torque limiter that generates a predetermined torque by the diameter expanding action that occurs in the coil spring (4) at the time,
Arc portions (33) and (34) having a larger radius of curvature than the coil portion (4a) in a free state are provided in the vicinity of each end including both ends of the coil spring (4), and these arc portions (33) and (34) are provided. ) Is substantially equal to the radius of curvature of the coil portion (4a) in a state where the coil spring (4) is expanded and attached to the inner ring (2) with a required tightening allowance. Each side surface (12a) (18a) of the outer ring member projection (12) provided on the outer ring member (1) and the lid member projection (18) provided on the lid member (3) is set to a size. ) Is inclined by a certain angle θ with respect to the radial reference line L1 of the outer ring member (1), and the arc portion (33) is provided between the inclined side surfaces (12a) (18a) and the inner ring (2). ) (34) Each tip surface (33 ') (34') Torque limiter characterized by   The torque limiter according to claim 1, characterized in that each arc portion (33) (34) is formed to have a length substantially equal to a half turn of the coil portion (4a).   Regulating protrusions (28), (31) for restricting the bending of the coil spring (4) above a certain amount on the inner diameter surface of either or both of the outer ring member (1) and the lid member (3) in the circumferential direction. The torque limiter according to claim 1, wherein the torque limiter is provided at a predetermined interval.

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