Torque limiter

Abstract

To provide: a new reverse input cutoff clutch with which a rolling element 10 is prevented from being excessively wedged between a cam surface 42 and the inner circumferential surface of an outer ring 4 when another side member 8 begins to rotate; and a torque limiter based on the reverse input cutoff clutch.SOLUTION: The cross-sectional shape of a circumferential end part 46 of the cam surface 42 is configured to extend linearly toward the radial outside while being inclined in the circumferential direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to to Regarding Lucre Limiter. [Background technology]

[0002] Conventionally, a reverse input cutoff clutch has been used that utilizes the bite of rolling elements. but It has been widely put to practical use. One example of such a clutch is the reverse input cutoff clutch shown in Patent Document 1 below. This reverse input cutoff clutch includes a cylindrical outer ring and a one-side member and an other-side member that can rotate around a common rotation axis within the outer ring. The outer ring has an inner peripheral surface with a circular cross section, and a one-side engagement piece attached to the one-side member and an other-side engagement piece attached to the other-side member are arranged in combination on the inside of the outer ring. The other-side engagement piece is formed with a concave cam surface that faces the inner peripheral surface of the outer ring, and a rolling element is arranged between the cam surface and the inner peripheral surface of the outer ring. The cross-sectional shapes of the two ends located on both sides of the cam surface in the circumferential direction both extend in a convex arc shape toward the radially outward direction. When the one-side member rotates relative to the outer ring, the one-side engagement piece pushes the rolling elements together with the other-side engagement piece to rotate the other-side member, but even if the other-side member tries to rotate relative to the outer ring, the rolling elements are unable to rotate because they are caught between the inner peripheral surface of the outer ring and the circumferential end of the cam surface. Therefore, if an operation to transmit rotation from the one-side member to the other-side member is an input, and an operation to transmit rotation from the other-side member to the one-side member is a reverse input, the input is transmitted but the reverse input is blocked.

[0003] Furthermore, by accommodating the outer ring together with the one-side member and the other-side member in a fixed housing and disposing a braking torque applying means between the outer ring and the housing for applying a braking torque to the outer ring when the outer ring rotates relative to the housing, the above-mentioned reverse input cutoff clutch can be used as a torque limiter in which the rotation from the one-side member to the other-side member is transmitted with no load or a light load, while the rotation from the other-side member to the one-side member is transmitted against the braking torque. An example of this is shown in Patent Document 2 below.

[0004] Such a torque limiter is used, for example, as an angular position maintaining device in the opening and closing mechanism of a hatchback of a passenger vehicle. In this case, if an electric motor, which is a driving member, is connected to one side member and the hatchback, which is a driven member, is connected to the other side member, the electric motor can swing the hatchback open and close with no or light load, while when the hatchback is fully open or in an intermediate angle position, the angular position of the hatchback is maintained by the braking torque described above without using any other brake mechanism such as an electromagnetic brake. Therefore, the angular position maintaining device can be constructed compactly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-174320 A [Patent Document 2] International Publication No. 2015 / 137231 Summary of the Invention [Problem to be solved by the invention]

[0006] In the reverse input cutoff clutch shown in the above Patent Document 1, the cross-sectional shape of the circumferential end of the cam surface of the other side engagement piece extends radially outward in a convex arc shape, so that at the end, the ratio (slope) of change in the distance between the cam surface and the inner peripheral surface of the outer ring to the moving distance (displacement) on the cam surface is small. Due to this, when the other side member tries to rotate, the rolling body tends to be deeply (i.e., more circumferentially outward) interlocked between the cam surface and the inner peripheral surface of the outer ring. Therefore, if the rotational torque applied to the other side member is large, the interlocking becomes excessive and the other side member may be locked, that is, completely immobilized. In this case, even if the one side member rotates relative to the outer ring, the one side engagement piece cannot move the rolling body even if it pushes it, so it cannot push the other side engagement piece, and therefore the other side member cannot be rotated, and the function as a reverse input cutoff clutch cannot be performed. In other words, it is a malfunction. Although the above Patent Document 2 does not clearly state the cross-sectional shape of the cam surface, as far as the drawings are concerned, the cross-sectional shape of the circumferential end of the cam surface extends in a convex arc shape circumferentially toward the radially outward direction, and has the same risks as those described above with respect to the reverse input cut-off clutch shown in the above Patent Document 1.

[0007] The present invention has been made in view of the above facts, Technique The technical problem is how to prevent the rolling elements from being excessively caught between the cam surface and the inner peripheral surface of the outer ring when the other member tries to rotate. The opposite Input cutoff clutch Using The object of the present invention is to provide a torque limiter that has a high torque limiting effect. [Means for solving the problem]

[0008] As a result of intensive research, the inventors have found that the cross-sectional shape of the circumferential end of the cam surface is configured to be inclined in the circumferential direction toward the radially outward and extend linearly, thereby Writing It was found that this could solve technical problems.

[0009] That is, according to the present invention, Writing As a reverse input cutoff clutch that solves technical problems, A fixed housing; and a sensor housed in the housing.The rotor includes a cylindrical outer ring and one side member and an other side member that are rotatable about a common rotation axis within the outer ring, a braking torque applying means is disposed between the housing and the outer ring, the braking torque applying means applying a braking torque to the outer ring when the outer ring rotates relative to the housing, The outer ring has an inner peripheral surface having a circular cross section, and a one-side engagement piece attached to the one-side member and a other-side engagement piece attached to the other-side member are arranged in combination on the inside of the outer ring, The other side engagement piece The exterior a cam surface is formed on the outer ring so as to face the inner peripheral surface of the outer ring, The cross-sectional shape of the cam surface at the end in the circumferential direction extends linearly and inclined in the circumferential direction toward the radially outward side, A rolling element is disposed between the cam surface and the inner peripheral surface of the outer ring, When the one-side member rotates, the outer ring is held by the braking torque, and the one-side engagement piece pushes the rolling body together with the other-side engagement piece, so that the rotation from the one-side member to the other-side member is transmitted with no load or a light load, while when the other-side member rotates, the rolling body is engaged between the inner peripheral surface of the outer ring and the circumferential end of the cam surface, so that the rotation from the other-side member to the one-side member can be transmitted against the braking torque. is provided.

[0010] Preferably, the cam surface is concave, and the cross-sectional shapes of the two ends located on both sides in the circumferential direction of the cam surface both extend linearly and inclined radially outward in the circumferential direction. In this case, the interior angle between the two straight lines along the two ends located on both sides in the circumferential direction is preferably 165 to 175 degrees.

[0011] Preferably, the braking torque applying means is a coil spring attached to the outer peripheral surface of the outer ring, the coil spring including a winding portion in which a wire is wound in a spiral shape and two hook portions in which the wire is bent radially outward at both axial ends of the winding portion, When the coil spring is in a free state, an inner diameter of the wound portion is smaller than an outer diameter of the outer ring having a cylindrical shape, The two hook portions are disposed at different positions in the circumferential direction, and the two hook portions are inserted into hook grooves formed in the inner peripheral surface of the housing, so that the coil spring cannot rotate relative to the housing. When the outer ring tries to rotate relative to the housing, one of the two hook portions is relatively pressed in the hook groove in a direction in which the winding portion expands in diameter. It is preferable that an auxiliary braking torque applying means is disposed within the housing for applying a braking torque to the rolling element. In this case, auxiliary The braking torque applying means is preferably a wave washer for axially biasing the rolling elements. Effect of the Invention

[0012] The present invention Torque limiter In the case of the cam surface, the cross-sectional shape of the circumferential end portion extends linearly while inclining in the circumferential direction toward the radially outward direction, so that the ratio of the change in the distance between the cam surface and the inner circumferential surface of the outer ring to the circumferential movement distance (displacement amount) on the cam surface at the end portion is sufficiently large. This prevents the rolling elements from being excessively deeply caught between the cam surface and the inner circumferential surface of the outer ring when the other-side member tries to rotate, and thus prevents the other-side member from being locked.

[0013] It should be noted in advance that the above-mentioned Patent Documents 1 and 2 disclose that the cross-sectional shape of the circumferential end of the cam surface is a convex arc or a convex arc shape, that is, a curve, but do not consider making it a straight line. Included in the torque limiter The reverse input cutoff clutch exhibits the above-mentioned special operational effects because the cross-sectional shape of the circumferential end of the cam surface is linear as described above. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing the structure of a preferred embodiment of a torque limiter constructed according to the present invention; [Diagram 2] FIG. 2 is an exploded view of the torque limiter shown in FIG. 1, with each component part arranged in the exploded view. [Diagram 3] 2 is a diagram showing the internal structure of the torque limiter shown in FIG. 1 with the shield removed. [Figure 4] FIG. 2 is a view showing one side member of the torque limiter shown in FIG. 1 alone. [Diagram 5] 2 is a view showing the other member of the torque limiter shown in FIG. 1 alone. FIG. [Figure 6] FIG. 2 is a view showing a housing of the torque limiter shown in FIG. 1 alone. [Figure 7] 2 is a diagram showing a state in which a rotational torque is applied to one side member in the torque limiter shown in FIG. 1; [Figure 8] 2 is a diagram showing a state in which a rotational torque is applied to the other-side member in the torque limiter shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The following is a configuration according to the present invention. TAT The limiter will be described in more detail with reference to the attached drawings. In the following description, the terms "one axial side" and "other axial side" refer to the right side and the left side in the state shown in the AA cross section of Figure 1, unless otherwise specified.

[0016] 1 to 3 show a configuration according to the present invention. Ruto A preferred embodiment of the limiter is shown. This torque limiter is numbered 2, and the reverse input cutoff clutch included in this torque limiter 2 is numbered 1. The reverse input cutoff clutch 1 comprises a cylindrical outer ring 4, one side member 6, the other side member 8, and rolling elements 10. The torque limiter 2 further comprises a housing 12 and a braking torque applying means 14.

[0017] The reverse input cutoff clutch 1 will be described. With reference to Figs. 1 to 3 and Fig. 4, the metallic one-side member 6 includes a one-side main portion 16 extending in the axial direction and a one-side engagement piece 18 attached to the one-side main portion 16 and extending in the axial direction. The one-side main portion 16 has a circular cross-sectional shape, and is divided into a small diameter portion 20, a medium diameter portion 22, and a large diameter portion 24 from one side to the other in the axial direction. The small diameter portion 20, the medium diameter portion 22, and the large diameter portion 24 have a common central axis, and a through hole 26 having a circular cross-sectional shape that penetrates the one-side main portion 16 in the axial direction is formed along the central axis. The small diameter portion 20 has a longer axial length than the medium diameter portion 22 and the large diameter portion 24. A one-side connection portion 28 is formed on the outer circumferential surface of the small diameter portion 20, and the one-side member 6 is connected to either one of the external devices on the driving side or the driven side (not shown) via the one-side connection portion 28. In the illustrated embodiment, the one-side connecting portion 28 is a male serration consisting of numerous ridges that extend linearly in the axial direction at intervals in the circumferential direction. A circular recess 29 is formed in the center of the other axial end face of the large diameter portion 24, which causes an annular ridge 30 to remain on the outer circumferential edge. Five one-side engaging pieces 18 are arranged at equal angular intervals in the circumferential direction. The cross-sectional shape of the one-side engaging piece 18 is a substantially T-shape with the radially inner ends of both circumferential ends of a sector cut out into a substantially rectangular shape, and both circumferential end faces of the one-side engaging piece 18 are partitioned into an outer pressing portion 32 located on the radially outer side and protruding outward in the circumferential direction, and an inner pressing portion 34 located on the radially inner side and recessed inward in the circumferential direction. The one-side engaging piece 18 is 、 One end is connected to the other axial end face of the annular ridge 30 and the other axial end portion of the outer circumferential surface of the large diameter portion 24, and extends to the other axial side beyond the other axial end face of the one-side main portion 16. Therefore, when viewed in the axial direction, the inner peripheral edge of the one-side engagement piece 18 is located in the radial middle portion of the annular ridge 30, and the outer peripheral edge is located radially outward of the outer circumferential edge of the large diameter portion 24.

[0018] 1 to 3 and also with reference to FIG. 5, the metallic other-side member 8 includes a cylindrical other-side main portion 36 penetrating in the axial direction, and an other-side engagement piece 38 attached to the outer circumferential surface of the other-side main portion 36 and extending in the axial direction. An other-side connection portion 40 is formed on the inner circumferential surface of the other-side main portion 36, and the other-side member 8 is connected to either a driving side or a driven side external device (not shown) via the other-side connection portion 40. In the illustrated embodiment, the other-side connection portion 40 is a female serration consisting of a number of protrusions that extend linearly in the axial direction at intervals in the circumferential direction. The other-side engagement pieces 38 are arranged in accordance with the number of one-side engagement pieces 18 formed on the one-side member 6, that is, five in the illustrated embodiment. The five other-side engagement pieces 38 are arranged at equal angular intervals in the circumferential direction. The other-side engagement pieces 38 extend from one axial end of the other-side main portion 36 to an axial middle portion. to Extending in the axial direction The other side engagement piece 38 The cross-sectional shape (cross-sectional shape as viewed in the axial direction) of the second main portion 36 has a cam surface 42 facing radially outward, and a circumferentially pressed surface 44 extending linearly radially inward from both circumferential ends of the cam surface 42 and connected to the outer circumferential surface of the other main portion 36. Included in the torque limiter In the reverse input cutoff clutch, it is important that the cross-sectional shape of the end 46 of the cam surface 42 extends linearly, inclined in the circumferential direction toward the radially outward direction. In the illustrated embodiment, the cross-sectional shape of the cam surface 42 extends linearly on both sides in the circumferential direction from a valley line 48 that extends linearly parallel to the central axis, and is symmetrical with respect to a line L0 passing through the valley line 48 and the central axis. In other words, the cam surface 42 is concave, and the cross-sectional shapes of the two end portions 46 located on both sides in the circumferential direction of the cam surface 42 both extend linearly, inclined outward in the circumferential direction toward the radially outward direction. When the inner diameter of the outer ring 4 is 16.2 mm and the outer diameter of the rolling element 10 is 2.0 mm, the interior angle θ of the two straight lines L1 and L2 along the end portions 46 on both sides in the circumferential direction of the cam surface is preferably 165 to 175 degrees, and in the illustrated embodiment, the interior angle θ is 172 degrees.

[0019] The one-side member 6 and the other-side member 8 are arranged in the outer ring 4 so as to be rotatable about a common rotation axis o. At that time, the one-side engagement piece 18 attached to the one-side member 6 and the other-side engagement piece 38 attached to the other-side member 8 are arranged in combination. In the illustrated embodiment, the outer ring 4 has a cylindrical shape penetrating in the axial direction and has inner and outer circumferential surfaces with circular cross sections. As shown in FIG. 3, when viewed in the axial direction, the one-side engagement piece 18 and the other-side engagement piece 38 are arranged alternately in the circumferential direction inside the outer ring 4, and the rolling element 10 is arranged between the cam surface 42 and the inner circumferential surface of the outer ring 4. In the illustrated embodiment, the rolling element 10 is a metallic roller having a cylindrical shape. The outer pressing portion 32 defined on the circumferential end surface of the one-side engagement piece 18 faces the rolling element 10, and the inner pressing portion 34 faces the circumferential pressed surface 44 of the other-side engagement piece 38, respectively, in the circumferential direction. At this time, as shown in the cross-sectional view along line AA in Figure 1, one axial side portion of the other-side member 8 is accommodated inside the one-side engagement piece 18 of the one-side member 6, and one axial side end face of the other-side member 8 faces the axial end face of the annular ridge 30 of the one-side member 6 and is supported in the axial direction thereby.

[0020] The operation of the reverse input cutoff clutch 1 will now be described. When the one-side member 6 rotates clockwise relative to the outer ring 4 (as viewed from the right of the AA cross section in Figure 1; the same applies below), as can be understood by comparing Figures 3 and 7, the one-side engagement piece 18 moves clockwise relative to the other-side engagement piece 38 and the rolling body 10, and the inner pressing portion 34 (more specifically, the inner pressing portion 34 on the downstream clockwise side) of the one-side engagement piece 18 presses the circumferential pressed surface 44 (more specifically, the circumferential pressed surface 44 on the upstream clockwise side) of the other-side engagement piece 38 (more specifically, the other-side engagement piece 38 located downstream in the clockwise direction), and the outer pressing portion 32 (more specifically, the outer pressing portion 32 on the downstream clockwise side) presses the rolling body 10 (more specifically, the rolling body 10 located downstream in the clockwise direction), causing the other-side member 8 to rotate clockwise. At this time, the rolling element 10 is pressed together with the other-side engagement piece 38, preventing the rolling element 10 from moving relative to the cam surface 42, and the rolling element 10 does not become caught between the cam surface 42 and the inner peripheral surface of the outer ring 4. The same applies when the one-side member 6 rotates counterclockwise relative to the outer ring 4.

[0021] On the other hand, when the other-side member 8 attempts to rotate clockwise relative to the outer ring 4, as can be understood by comparing Figures 3 and 8, the other-side engagement piece 38 moves clockwise relative to the one-side engagement piece 18 and the rolling element 10, causing the rolling element 10 to move relatively from the circumferential central region of the cam surface 42 to the end 46 upstream in the clockwise direction, and the rolling element 10 gets caught at the end 46 between the cam surface 42 and the inner circumferential surface of the outer ring 4. This prevents the other-side member 8 from rotating relative to the outer ring 4. The same applies when the other-side member 8 attempts to rotate counterclockwise relative to the outer ring 4.

[0022] That is, in the reverse input cutoff clutch 1, when the one-side member 6 rotates relative to the outer ring 4, the one-side engagement piece 18 together with the other-side engagement piece 38 pushes the rolling element 10 to rotate the other-side member 8, but even if the other-side member 8 tries to rotate relative to the outer ring 4, the rolling element 10 gets caught between the inner circumferential surface of the outer ring 4 and the cam surface 42, more specifically, between the end 46 of the cam surface 42, and cannot rotate. Therefore, if an operation to transmit rotation from the one-side member 6 to the other-side member 8 is taken as an input, and an operation to transmit rotation from the other-side member 8 to the one-side member 6 is taken as a reverse input, the input is transmitted but the reverse input is cut off.

[0023] Here, the present invention Included in the torque limiter In the reverse input cutoff clutch, the cross-sectional shape of the circumferential end 46 of the cam surface 42 extends linearly while inclining in the circumferential direction toward the radially outward direction, so that the ratio of change in the distance L (see the enlarged view of part X in FIG. 3) between the cam surface 42 and the inner circumferential surface of the outer ring 4 to the circumferential movement distance (displacement amount) on the cam surface 42 at the end 46 is sufficiently large. This prevents the rolling element 10 from being excessively deeply engaged between the cam surface 42 and the inner circumferential surface of the outer ring 4 when the other-side member 8 tries to rotate, thereby preventing the other-side member 8 from being locked. Therefore, when the one-side member 6 rotates relative to the outer ring 4, the one-side engagement piece 18 pushes the other-side engagement piece 38 together with the rolling element 10, and the other-side member 8 can be rotated sufficiently and reliably.

[0024] Next, we will explain the torque limiter 2 that uses the reverse input cutoff clutch 1. As described above, the torque limiter 2 further includes a housing 12 and a braking torque applying means 14. The housing 12 accommodates the outer ring 4 together with the one-side member 6 and the other-side member 8, and is fixed to a wall or the like by appropriate fixing means (not shown).

[0025] Explaining with reference to FIG. 6 together with FIG. 1 to FIG. 3, the housing 12 is composed of a housing body 50 made of synthetic resin as shown in FIG. 6(a) and a shield 52 made of synthetic resin as shown in FIG. 6(b). The housing body 50 has a circular end plate 54 arranged perpendicular to the axial direction, and a cylindrical outer peripheral wall 56 extending from the outer peripheral edge of the end plate 54 to one side in the axial direction. A support hole 58 having a circular cross section penetrating in the axial direction is formed in the center of the end plate 54, and a ring-shaped shoulder portion 60 with a reduced inner diameter is formed at the other axial end of the support hole 58. The other axial end of the other member 8 is inserted into the support hole 58, and this other axial end is rotatably supported by the support hole 58 and supported in the axial direction by the shoulder portion 60. Six arc-shaped recesses 62 are formed at equal angular intervals in the circumferential direction at the radial middle portion of one axial side surface of the end plate 54. The recesses 62 are formed for the purpose of so-called thickness removal. Six arc-shaped seating portions 64 are formed at equal angular intervals in the circumferential direction on the outer peripheral edge of one axial side of the end plate 54, which are connected to the inner peripheral surface of the outer peripheral wall 56 and protrude to one axial side. All six seating portions 64 have the same shape. The circumferential center positions of the seating portions 64 and the circumferential center positions of the recessed portion 62 are aligned, and the circumferential length of the seating portions 64 is somewhat shorter than the circumferential length of the recessed portion 62. Auxiliary ridges having arc-shaped cross sections are formed on the upper surfaces of the six seating portions 64, which are connected to the inner peripheral surface of the outer peripheral wall 56 and extend to one axial side. The six auxiliary ridges are indicated by 66a to 66f in the clockwise direction in the right drawing of FIG. 6(a). The inner diameters of the auxiliary ridges 66a to 66f are larger than the inner diameter of the seat portion 64, and as shown in Fig. 3, the inner peripheral surfaces of the auxiliary ridges 66a to 66f face the outer peripheral surface of a wound portion 90 (described later) of the braking torque applying means (coil spring 14). When viewed in the axial direction, that is, in the right diagram of Fig. 6(a), both circumferential ends of the auxiliary ridges 66b and 66e match with both circumferential ends of the respective seat portions 64. However, for the auxiliary ridges 66a and 66d, although the respective clockwise downstream ends match with the clockwise downstream ends of the respective seat portions 64, the respective clockwise upstream ends are displaced downstream of the clockwise upstream ends of the respective seat portions 64.Furthermore, the clockwise upstream ends of the auxiliary ribs 66c and 66f are aligned with the clockwise upstream ends of the respective seating portions 64, but the clockwise downstream ends of the auxiliary ribs 66c and 66f are displaced upstream from the clockwise downstream ends of the respective seating portions 64. As a result, the circumferential gaps between the circumferentially adjacent auxiliary ribs 66a and 66f and between the auxiliary ribs 66c and 66d are wider than the circumferential gaps between the other two circumferentially adjacent auxiliary ribs, and hook grooves 68 are defined between the auxiliary ribs 66a and 66f and between the auxiliary ribs 66c and 66d. That is, the hook grooves 68 are formed on the inner peripheral surface of the housing 12. Six arc-shaped extension pieces 70 extending further toward one axial side are provided at equal angular intervals in the circumferential direction on one axial end face of the outer peripheral wall 56. When viewed in the axial direction, the six extension pieces 70 are each disposed between two circumferentially adjacent pedestal portions 64. A locking protrusion 72 is formed on the inner surface of the extending end portion of each extension piece 70 and extends in the circumferential direction.

[0026] The shield 52 comprises a disk-shaped support wall 74 disposed perpendicular to the axial direction, and a cylindrical mounting wall 76 extending from the outer periphery of the support wall 74 to one side in the axial direction. A circular hole 78 is formed in the center of the support wall 74, penetrating in the axial direction. Two annular ridges, namely an outer ridge 80 and an inner ridge 82, are formed on the other axial side of the support wall 74, and an annular groove 84 is provided between the outer ridge 80 and the inner ridge 82. The inner ridge 82 surrounds the outer periphery of the hole 78, and is somewhat lower from the support wall 74 than the outer ridge 80. AA cross section of 11, one axial end of the outer ring 4 is inserted into the groove 84, and the groove 84 rotatably supports the one axial end of the outer ring 4. An arc-shaped protrusion 86 having an increased outer diameter is formed on the outer peripheral surface of the mounting wall 76. A plurality of protrusions 86 are formed corresponding to the number of extension pieces 70 formed on the housing main body 50, i.e., six in the illustrated embodiment, and the plurality of protrusions 86 are arranged at equal angular intervals in the circumferential direction. The circumferential interval between two circumferentially adjacent protrusions 86 corresponds to the circumferential length of the extension pieces 70. A circumferentially extending engaged protrusion 88 is formed in the axially intermediate portion of the outer peripheral surface of the mounting wall 76 between two circumferentially adjacent protrusions 86. When the shield 52 is attached to the housing body 50, the extension piece 70 of the housing body 50 is aligned between two circumferentially adjacent protrusions 86, and then the shield 52 is forced in the axial direction toward the end plate 54 of the housing body 50, so that the locking protrusions 72 of the extension piece 70 elastically ride over the locked protrusions 88. When the shield 52 is attached to the housing body 50, the medium diameter portion 22 of the one-side member 6 is positioned inside the hole 78 formed in the support wall 74, and the Axial direction other side The inner peripheral edge portion faces one axial end face of the large diameter portion 24 of the one-side member 6 and supports it in the axial direction.

[0027] Explaining with reference to Figures 1 to 3, in the illustrated embodiment, the braking torque applying means 14 is a coil spring, which is attached to the outer peripheral surface of the outer ring 4. Below, the coil spring is designated by the number 14. The coil spring 14 has a wound portion 90 in which a wire is wound in a spiral shape, and two hook portions 92 in which the wire is bent radially outward at both axial ends of the wound portion 90. When the coil spring 14 is in a free state, that is, when no force is acting on either of the two hook portions 92, the inner diameter of the wound portion 90 is smaller than the outer diameter of the cylindrical outer ring 4, Therefore,The inner peripheral surface of the wound portion 90 is in close contact with the outer peripheral surface of the outer ring 4. The two hook portions 92 are arranged at different positions in the circumferential direction, and the two hook portions 92 are inserted into the hook grooves 68 formed in the inner peripheral surface of the outer peripheral wall 56 of the housing main body 50. In the illustrated embodiment, two hook grooves 68 are formed in the inner peripheral surface of the outer peripheral wall 56, and the two hook portions 92 are commonly inserted into either one of the two hook grooves 68. By commonly inserting the two hook portions 92 into the hook grooves 68, the coil spring 14 becomes unable to rotate with respect to the housing 12, and when the outer ring 4 tries to rotate with respect to the housing 12, one of the two hook portions 92 is relatively pushed by the housing 12 in the hook groove 68 in the direction in which the wound portion 90 expands in diameter.

[0028] Explaining with reference to FIG. 1 and FIG. 2, in the illustrated embodiment, an auxiliary braking torque applying means for applying a braking torque to the rolling element 10 is further disposed in the housing 12. The braking torque applied to the rolling element 10 by the auxiliary braking torque applying means is smaller than the braking torque applied to the outer ring 4 by the braking torque applying means (coil spring 14). In the illustrated embodiment, the auxiliary braking torque applying means is a wave washer 94. The wave washer 94 is a metal thin plate annular member processed into a corrugated shape, and biases the rolling element 10 in the axial direction. The above-mentioned braking torque is applied to the rolling element 10 due to the frictional force caused by such bias. As can be understood by referring to the AA line cross-sectional view in FIG. 1, both axial ends of the rolling element 10 are supported by metal thin plate annular washers 96a and 96b. The inner diameters of the washer 96a located on the shield 52 side and the washer 96b located on the end plate 54 side of the housing body 50 are approximately equal. On the other hand, the outer diameter of the washer 96a is smaller than the outer diameter of the washer 96b, and the washer 96a is housed inside the outer ring 4, while the washer 96b is outside the outer ring 4 and supports the other axial end face of the outer ring 4 together with the other axial end face of the rolling element 10. As described above, Outer ring 4One axial end of the washer 96 is rotatably supported by a groove 84 formed in the shield 52. The wave washer 94 is disposed axially adjacent to the washer 96a on the inside of the outer ring 4. A washer 96c having the same shape as the washer 96a is also disposed between the wave washer 94 and the shield 52.

[0029] The operation of the torque limiter 2 will now be described. The case where the one-side member 6 rotates in the clockwise direction will be described with reference to FIG. 3 and FIG. 。 As mentioned above, When one side member 6 rotates clockwise, The inner pressing portion 34 (more specifically, the inner pressing portion 34 on the downstream side in the clockwise direction) of the one-side engagement piece 18 presses the circumferential pressed surface 44 (more specifically, the circumferential pressed surface 44 on the upstream side in the clockwise direction) of the other-side engagement piece 38, and the outer pressing portion 32 (more specifically, the outer pressing portion 32 on the downstream side in the clockwise direction) presses the rolling element 10 (more specifically, the rolling element 10 located on the downstream side in the clockwise direction), causing the other-side member 8 to rotate in the clockwise direction. At this time, the outer ring 4 is held by the coil spring 14, and the one-side member 6 and the other-side member 8 rotate together with the rolling element 10 relative to the outer ring 4 and the housing 12. In addition, in the illustrated embodiment, since an auxiliary braking torque is applied to the rolling element 10 by the wave washer 94, the one-side member 6 and the other-side member 8 rotate against the auxiliary braking torque, which is a relatively light load. The same applies when the one-side member 6 rotates in the counterclockwise direction.

[0030] Next, the case where the other-side member 8 rotates in the clockwise direction will be described with reference to Fig. 3 and Fig. 8. When the other-side member 8 rotates in the clockwise direction, as described above, the rolling element 10 is engaged between the cam surface 42 and the inner peripheral surface of the outer ring 4 at the end 46 on the upstream side in the clockwise direction. This engagement causes the other-side member 8, the rolling element 10, and the outer ring 4 to become one body. Therefore, when the other-side member 8 rotates in the clockwise direction, the coil spring 14 attached to the outer peripheral surface of the outer ring 4 also rotates in the clockwise direction, and the hook portion 92 located on the downstream side in the clockwise direction is locked by the housing 12 in the hook groove 68. At this time, the hook portion 92 is relatively pressed by the housing 12 in the direction in which the wound portion 90 expands in diameter, so that the other-side member 8 can rotate in the clockwise direction together with the rolling element 10 and the outer ring 4 against the braking torque by the coil spring 14 (braking torque applying means). Then, after the other-side member 8 rotates clockwise and the circumferential pressed surface 44 of the other-side engagement piece 38 (more specifically, the circumferential pressed surface 44 on the clockwise downstream side) comes into contact with the inner pressing portion 34 of the one-side engagement piece 18 (more specifically, the inner pressing portion 34 on the clockwise upstream side of the one-side engagement piece 18 located on the clockwise downstream side), the circumferential pressed surface 44 presses the inner pressing portion 34, causing the one-side member 6 to rotate clockwise. On the other hand, if the rotational torque applied to the other-side member 8 is smaller than the braking torque, the other-side member 8 does not rotate and is held by the braking torque. The same applies when the other-side member 8 rotates counterclockwise.

[0031] That is, in the torque limiter 2, the rotation from the one-side member 6 to the other-side member 8 is transmitted with a light load, while the rotation from the other-side member 8 to the one-side member 6 is transmitted against a relatively large braking torque by the coil spring 14 (braking torque applying means). Furthermore, in the illustrated embodiment, the rotation from the one-side member 6 to the other-side member 8 and the rotation from the other-side member 8 to the one-side member 6 can both be rotated in the forward and reverse directions, so that the torque limiter 2 is a bidirectional torque limiter. If the auxiliary braking torque applying means 94 is omitted, the rotation from the one-side member 6 to the other-side member 8 is transmitted with substantially no load, but in order to stabilize the posture of the rolling element 10 and ensure that it is meshed between the end 46 of the cam surface 42 and the inner circumferential surface of the outer ring 4 when a rotational torque that rotates the one-side member 6 is applied from the other-side member 8, it is preferable to provide the auxiliary braking torque applying means 94.

[0032] As described above, the present invention is configured TAT Although the torque limiter has been described in detail with reference to the attached drawings, the present invention is not limited to the above-described embodiment, and appropriate modifications and changes can be made without departing from the scope of the present invention. For example, in the illustrated embodiment, the rolling elements are cylindrical rollers, but they may be spherical balls. In addition, in the torque limiter, the braking torque applying means may be of any type as long as it can apply a braking torque to the outer ring, and leaf springs, ring springs, tolerance rings, etc. can be used in addition to coil springs. [Explanation of symbols]

[0033] 1: Reverse input cutoff clutch 2: Torque limiter 4: Outer ring 6: One-sided member 8: Other side member 10: Rolling element 12: Housing 14: Braking torque applying means (coil spring) 18: One-sided engagement piece 38: Other side engagement piece 42: Cam surface 46: End of (cam surface)

Claims

1. The rotor includes a cylindrical outer ring and one side member and an other side member that are rotatable about a common rotation axis within the outer ring, The outer ring has an inner peripheral surface having a circular cross section, and a one-side engagement piece attached to the one-side member and a other-side engagement piece attached to the other-side member are arranged in combination on the inside of the outer ring, The other-side engagement piece is formed with a cam surface that faces an inner peripheral surface of the outer ring, and a rolling element is disposed between the cam surface and the inner peripheral surface of the outer ring, In a reverse input cutoff clutch, when the one-side member rotates relative to the outer ring, the one-side engagement piece pushes the rolling body together with the other-side engagement piece to rotate the other-side member, while even if the other-side member tries to rotate relative to the outer ring, the rolling body is caught between the inner peripheral surface of the outer ring and the end portion in the circumferential direction of the cam surface and cannot rotate, A reverse input cutoff clutch, characterized in that the cross-sectional shape of the end of the cam surface extends linearly and is inclined circumferentially toward the radially outward side.

2. 2. The reverse input cut-off clutch according to claim 1, wherein the cam surface is concave, and the cross-sectional shapes of the two ends located on both circumferential sides of the cam surface both extend linearly and inclined radially outwardly in the circumferential direction.

3. 3. The reverse input cutoff clutch according to claim 2, wherein an interior angle between two straight lines along the two ends located on both sides in the circumferential direction is 165 to 175 degrees.

4. A torque limiter using the reverse input cutoff clutch according to any one of claims 1 to 3, the outer ring is accommodated in a fixed housing together with the one-side member and the other-side member, and a braking torque applying means is disposed between the outer ring and the housing, the braking torque applying means applying a braking torque to the outer ring when the outer ring rotates relative to the housing, A torque limiter in which rotation is transmitted from the one-side member to the other-side member with no load or a light load, while rotation is transmitted from the other-side member to the one-side member against the braking torque.

5. the braking torque applying means is a coil spring attached to the outer peripheral surface of the outer ring, the coil spring including a winding portion in which a wire is wound in a spiral shape and two hook portions in which the wire is bent radially outward at both axial ends of the winding portion, When the coil spring is in a free state, an inner diameter of the wound portion is smaller than an outer diameter of the outer ring having a cylindrical shape, 5. The torque limiter according to claim 4, wherein each of the two hook portions is arranged at a different circumferential position, the two hook portions are inserted into hook grooves formed in an inner peripheral surface of the housing so that the coil spring cannot rotate relative to the housing, and when the outer ring attempts to rotate relative to the housing, one of the two hook portions is pushed relatively in the hook groove in a direction in which the winding portion expands in diameter.

6. 5. The torque limiter according to claim 4, further comprising an auxiliary braking torque applying means disposed within said housing for applying a braking torque to said rolling elements.

7. 7. The torque limiter according to claim 6, wherein the braking torque applying means is a wave washer for axially biasing the rolling elements.

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