JP4467503B2 - 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. 7, a conventionally known spring-type torque limiter used in office machines 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 coil spring 44 (see FIG. 8), which disappears and the small diameter portion 44b. The inner ring 43 or the outer ring member 41 is in a state in which it cannot rotate until the entire diameter of the inner ring 43 increases. 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 assembling, an operation of inserting the hook over the engagement hole of the outer ring member or the like is necessary, which is a factor that hinders workability.

  In order to solve these problems, as shown in FIGS. 9 (a) and 9 (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. A structure that abuts against the side surface of the provided lid member projection 54 is conceivable.

  However, when such a coil spring 44 is attached to the inner ring 43 with a certain tightening margin, as shown in FIG. 10, the coil portion 56 is slightly enlarged in diameter and the radius of curvature is increased, 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. 11 (a) to 11 (c), the coil spring 44 used in this improved torque limiter has arc portions 57, 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 in which the coil spring 44 is expanded and attached to the inner ring 43 with the required tightening margin (see the dashed line in FIG. 11 (b), see FIG. 11 (c)). The size is set to be substantially equal to the curvature radius of the coil 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 according to the above application, the front end surfaces 57 ′ and 58 ′ are abutted against the outer ring member projection (not shown) and the side surface of the lid member projection 54 without providing hooks at both ends. Suitable for downsizing because of its 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 which can also suppress generation | occurrence | production 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 a change in the friction coefficient of the sliding surface between the coil spring and the inner ring, and the vibration is amplified by the coil spring, which causes 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 there is a limit to the additives that can be added to the base oil while so-called chemical attack is considered as a problem, so it is a sufficient countermeasure. I don't get it. 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. 11 (c), when the inner ring 43 rotates counterclockwise 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 end portion of the arc portion 57 is pushed outward (see the one-dot chain line in FIG. 11C). 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, A lid member that is fitted and fixed to the inner diameter surface of the coil spring 4 that is 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 and closes the outer ring surface of the inner ring. When one end of the coil spring 4 is engaged with the outer ring member protrusion 12 and the other end is engaged with the lid member protrusion 18, and the inner ring 2 and the outer ring member 1 rotate relative to each other. The following configuration was adopted on the premise of a torque limiter that generates a predetermined torque by the diameter expanding action generated in the coil spring 4.

  That is, as shown in FIGS. 4A and 4B, arc portions 33 and 34 having a radius of curvature larger than that of the coil portion 4a in the free state are provided in the vicinity of each end portion including both ends of the coil spring 4. The radius of curvature of the coil portion 4a is set to be 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. .

  Further, as shown in FIGS. 3A and 3B, the end surfaces 33 ′ and 34 ′ of the arc portions 33 and 34 are formed on the side surfaces 12 a and 18 a of the outer ring member protrusion 12 and the lid member protrusion 18. The restricting protrusions 28 and 31 that are abutted and restrict the deflection of the coil spring 4 to a certain degree or more on the inner surface of either or both of the outer ring member 1 and the lid member 3 are spaced apart from each other by a predetermined distance in the circumferential direction. And the coil spring 4 is interposed between the outer ring member protrusion 12 and the cover member protrusion 18 in a state where the coil spring 4 is compressed in the axial direction.

  In the torque limiter having the above-described configuration, the rigidity of the arc portions 33 and 34 is increased by incorporating the coil spring 4 in a compressed state in the axial direction, and vibration and abnormal noise due to the vibration are suppressed.

  In addition, when using the closely wound coil spring 4, the rigidity of the circular arc portions 33 and 34 is increased by generating an initial tension by applying a circumferential force to both the end surfaces 33 'and 34'. .

  As described above, the torque limiter according to the present invention reduces the rigidity of the arc portions 33 and 34 when both the arc portions 33 and 34 of the coil spring are provided to prevent interference with the inner ring 2. Rigidity is enhanced by incorporating the coil spring 4 in a state compressed in the axial direction or applying initial tension. Thereby, generation | occurrence | production of the vibration in a spring type torque limiter and the abnormal noise by the vibration can be suppressed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the torque limiter 10 according to 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 (axial length) is formed slightly larger than the size of the cross section of the wire constituting the coil spring 4, the end face 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.

  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 projection 18 is formed to be slightly larger than the size of the cross section of the wire constituting the coil spring 4, and the end 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 be in sliding contact with the outer diameter surface of the inner ring 2.

  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).

  The coil spring 4 is formed by winding a steel wire (a square wire in the case of illustration but a round wire) a required number of times so as to have a single diameter. 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 other than the arc portions 33 and 34 are formed slightly smaller than the outer diameter of the inner ring 2, when the inner ring 2 is fitted to the inner ring 2, it is mounted with a certain tightening allowance. In other words, the initial radius of curvature of each of the arc portions 33 and 34 is set to a size that is substantially equal to the radius of curvature of the other coil portions when mounted on the inner ring 2. By providing such arc portions 33 and 34 at both ends of the coil spring 4, interference between the end faces 33 'and 34' and the inner ring 2 is eliminated.

  The coil spring 4 is uniformly wound at a constant pitch P as shown in FIG. When the width of the wire (diameter in the case of a round wire) is a, the pitch P is set to a size not exceeding 3 times a and the number of turns is 8 or less. If the pitch P exceeds 3 times a, the wire forming the coil is liable to fall, and problems such as lack of stability of the inner diameter are caused. However, if it is set close to 3 times a within a range not exceeding 3 times a, the springs are less likely to be entangled in the manufacturing process of the coil spring 4, so that the assemblability is improved. On the other hand, if the number of turns exceeds 8, there is a possibility that the diameter expanding action at the time of torque generation may not be transmitted to the entire spring, and smooth rotation may be lacking.

  In addition, when setting pitch P to 3 times or more of a, it is good to use a round line. This is because the round wire does not collapse the wire.

  When the length between both ends of the coil spring 4 is L, and the distance between the inner end face 11 (see FIG. 1) of the outer ring member 1 and the inner end face 3 ′ of the lid member is L ′. , L> L ′. As a result, in the assembled state, the coil spring 4 is compressed in the axial direction, and both end portions exert a thrust force F on the boss portion inner end surface 11 and the lid member inner end surface 3 ′, respectively. As a result, the arc portions 33 and 34 have high rigidity.

  The coil spring 4 is mounted on the outer diameter surface of the inner ring 2 in advance, and this is incorporated into the outer ring member 1 and the lid member 3 is fitted. When 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 direction opposite to the winding direction of the coil spring 4 when viewed from the lid member 3 side, One end face 34 'of the coil spring 4 hits the side face 18a of the member protrusion 18 (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 'contacts the side surface 12a of the outer ring member protrusion 12 (see FIG. 3A). Thereby, both end surfaces 33 ′ and 34 ′ of the coil spring 4 are engaged with the outer ring member protrusion 12 and the lid member protrusion 18 without any gaps in the circumferential direction.

  In this assembled state, the inner surfaces of the restricting projections 28 of the outer ring member 1 and the restricting projections 31 of the lid member 3 are constant surfaces over the entire length of the outer diameter surface of the coil spring 4 in the axial direction. 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. As in the conventional case, torque is generated in accordance with the diameter expanding action of the coil spring 4 due to the relative rotation of the outer ring member 1 and the inner ring 2. Since it is in the state compressed in the axial direction and the force F in the thrust direction acts, the rigidity of both the arc portions 33 and 34 is increased, so that the generation of vibration and abnormal noise due to the vibration is suppressed.

  In addition, the deflection 52 (see FIG. 8) that has conventionally occurred at the coil end in the initial generation of torque is restricted by the inner diameter surface of the restricting protrusions 28 and 31 being restricted, and the expansion of the coil end is restricted. The generation | occurrence | production is suppressed by this. For this reason, there is no backlash in the initial generation of torque, and the coil spring 4 has a diameter expanding action, and torque is immediately generated.

  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.

  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.

  The coil spring 4 is wound evenly over the entire length, but instead is wound tightly over the entire length as shown in FIG. 5, and densely wound at both ends as shown in FIG. A winding portion 35 may be provided, and a uniform winding portion 36 may be formed between the closely wound portions 35.

  Since the one wound tightly over the entire length cannot be compressed in the axial direction, in this case, the lid member 3 is rotated from the outside, and the lid member protrusion 18 is pressed against the distal end surface 34 'so that the coil spring 4 is moved. When rotating and pressing the distal end surface 33 ′ at the other end against the outer ring member protrusion 12 on the fixed side, a circumferential tension (initial tension) is applied to the coil spring 4 as shown by an arrow in FIG. By adding, it is possible to increase the overall rigidity including the arc portions 33 and 34, thereby suppressing the occurrence of vibration and abnormal noise.

  In addition, those having both the tightly wound portion 35 and the uniform wound portion 36 can be compressed in the axial direction due to the presence of the uniform wound portion 36, and at the same time, by applying initial tension to the densely wound portion 35. The rigidity of the arc portions 33 and 34 can be further increased.

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, and (c) is a partially enlarged sectional view of (a). (A) A sectional view of a coil spring in a natural state, (b) is a front view of the coil spring, and (c) is a sectional view of the coil spring in a mounted state. (A) Cross-sectional view of another coil spring in a natural state, (b) is a front view of the coil spring, and (c) is a cross-sectional view in a mounted state of the coil spring. (A) Cross-sectional view of another coil spring in a natural state, (b) is a front view of the coil spring, and (c) is a cross-sectional view in a mounted state of the coil spring. Sectional view of a conventional torque limiter Sectional view along line XX in FIG. (A) Cross-sectional view of another conventional example, (b) Perspective view of coil portion same as above. 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 35 Closely wound part 36 Uniformly wound part

Claims (5)

The outer ring member (1), the inner ring (2) inserted into the inner ring (1) and supported in a relatively rotatable manner at the boss part (5) at one end, and the outer ring surface of the inner ring (2) are mounted 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. When 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), the inner ring (2) and the outer ring member (1) rotate relative to each other. In the torque limiter which generates a predetermined torque by the diameter expanding action generated in the coil spring (4),
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 the magnitude of the radius of curvature is In the state where the coil spring (4) is expanded and attached to the inner ring (2) with a required tightening margin, the coil spring (4a) is set to a size substantially equal to the radius of curvature of the coil portion (4a). (33) Each end face (33 ') (34') of (34) has an outer ring member projection (12) provided on the outer ring member (1) and a lid member projection provided on the lid member (3). (4) constant of the coil spring is abutted against the side surfaces (12a) and (18a) of the part (18), and the inner ring surface of either the outer ring member (1) or the lid member (3) or both. The restricting protrusions (28) and (31) for restricting the above-described bending are in the circumferential direction. The coil spring (4) is provided between the outer ring member projection (12) and the lid member projection (18) in a state where the coil spring (4) is compressed in the axial direction. Torque limiter.   The torque limiter according to claim 1, wherein the coil spring (4) is a uniform winding.   The torque limiter according to claim 1, wherein a tightly wound portion is provided in a portion including both ends of the coil spring (4), and a uniform wound portion is provided between both closely wound portions.   The torque limiter according to claim 2 or 3, wherein a winding pitch of the uniform winding portion does not exceed three times a thickness of the spring wire. The outer ring member (1), the inner ring (2) inserted into the inner ring (1) and supported in a relatively rotatable manner at the boss part (5) at one end, and the outer ring surface of the inner ring (2) are mounted 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. When 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), the inner ring (2) and the outer ring member (1) rotate relative to each other. In the torque limiter which generates a predetermined torque by the diameter expanding action generated in the coil spring (4),
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 the magnitude of the radius of curvature is In the state where the coil spring (4) is expanded and attached to the inner ring (2) with a required tightening margin, the coil spring (4a) is set to a size substantially equal to the radius of curvature of the coil portion (4a). (33) Each end face (33 ') (34') of (34) has an outer ring member projection (12) provided on the outer ring member (1) and a lid member projection provided on the lid member (3). (4) constant of the coil spring is abutted against the side surfaces (12a) and (18a) of the part (18), and the inner ring surface of either the outer ring member (1) or the lid member (3) or both. The restricting protrusions (28) and (31) for restricting the above-described bending are in the circumferential direction. The coil spring (4) is closely wound, and an initial tension is applied between the outer ring member projection (12) and the lid member projection (18). Torque limiter.

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