Bidirectional torque limiter

Abstract

The invention provides a novel bidirectional torque limiter which has a small number of components and is easy to assemble. The present invention relates to a bidirectional torque limiter, and more particularly, to a bidirectional torque limiter capable of changing the magnitude of a rotational torque that starts to rotate when a rotational torque is applied from one of two members connected to each other, and the magnitude of a rotational torque that starts to rotate when a rotational torque is applied from the other of the two members connected to each other. An inner coil spring (76) and an outer coil spring (82) are attached to the inner peripheral surface and the outer peripheral surface of a common ring member (10), respectively.

Description

Technical Field

[0001] The present invention relates to a bidirectional torque limiter, and more particularly to a bidirectional torque limiter capable of varying the magnitude of a rotational torque which starts rotating when a rotational torque is applied from one of two connected members and the magnitude of a rotational torque which starts rotating when a rotational torque is applied from the other of the two connected members. Background Art

[0002] As an example of the above-mentioned bidirectional torque limiter, there is a bidirectional torque limiter shown in the following patent document 1 of the applicant of the present application (hereinafter, this bidirectional torque limiter is sometimes referred to as "the conventional bidirectional torque limiter"). The conventional bidirectional torque limiter includes a fixed housing, a one side member, an other side member, an outer ring and an inner ring, wherein the one side member, the other side member, the outer ring and the inner ring have a common central axis in the housing. A one side retaining plate extending in the axial direction is formed on the one side member, and a other side retaining plate extending in the axial direction is formed on the other side member, and the one side retaining plate and the other side retaining plate are combined and arranged in a manner that there are two gaps in the circumferential direction. An outer coil spring is installed on the outer circumferential surface of the outer ring. The inner diameter of the outer coil spring in a free state is smaller than the outer diameter of the outer ring, and the outer coil spring is in close contact with the outer ring with a relatively small force. If the torque generated by the close contact between the outer coil spring and the outer ring is called the outer retaining torque, then the outer retaining torque is relatively small. The outer coil spring has two outer hooks at different angular positions in the circumferential direction, and the two outer hooks are respectively inserted into the above-mentioned two gaps. An inner coil spring is installed on the outer circumferential surface of the inner ring. The inner diameter of the inner coil spring in a free state is smaller than the outer diameter of the inner ring, and the inner coil spring is in close contact with the inner ring with a relatively large force. If the torque generated by the inner coil spring and the inner ring being in close contact is called the inner retaining torque, then the inner retaining torque is relatively large. The inner coil spring has two inner hooks at different angular positions in the circumferential direction, and the two inner hooks are respectively inserted into hook grooves formed on the inner circumferential surface of the outer ring.

[0003] Furthermore, when a rotation torque is applied to the one-side member, the one-side locking piece presses one of the two outer hooks in the direction of the outer coil spring expanding in diameter. Since the outer coil spring is mounted on the outer peripheral surface of the outer ring, the outer ring wants to rotate together with the outer coil spring, and presses one of the two inner hooks of the inner coil spring in the direction of the inner coil spring expanding in diameter. At this time, the outer retaining torque is smaller than the inner retaining torque, so when the above-mentioned rotation torque applied to the one-side member is larger than the outer retaining torque, the outer coil spring slides relative to the outer ring before the inner coil spring slides relative to the inner ring. That is, before the inner coil spring starts to rotate relative to the inner ring, the outer coil spring starts to rotate relative to the outer ring in a state where the outer ring is held by the inner coil spring. Then, after the outer hook pressed by the one-side locking piece abuts against the other-side locking piece, the one-side locking piece presses the other-side locking piece via the outer hook, and the one-side member, the outer coil spring and the other-side member rotate as one. That is, the rotation applied to the one-side member is transmitted to the other-side member. In addition, when the said rotation torque applied to one side member is smaller than the outer holding torque, the one side member does not rotate but is held by the outer holding torque.

[0004] On the other hand, if a rotation torque is applied to the other side member, the other side locking piece presses one of the two outer hooks in the direction of the outer coil spring shrinking. As a result, the close contact between the outer coil spring and the outer ring is enhanced, and the outer ring wants to rotate with the outer coil spring. Since the outer coil spring is mounted on the outer peripheral surface of the outer ring, the outer ring wants to rotate with the outer coil spring and presses one of the two inner hooks of the inner coil spring in the direction of the inner coil spring expanding. Therefore, if the above-mentioned rotation torque applied to the other side member is greater than the inner side holding torque, the inner coil spring slides relative to the inner ring. That is, the inner coil spring starts to rotate relative to the inner ring, and the other side member, the outer coil spring, the outer ring and the inner coil spring become one and rotate relative to the inner ring. Moreover, after the outer hook pressed by the other side locking piece abuts against the one side locking piece, the other side locking piece presses the one side locking piece via the outer hook, and the other side member, the outer coil spring and the one side member (further the outer ring and the inner coil spring) become one and rotate. That is, the rotation applied to the other side member is transmitted to the one side member. It should be noted that, when the rotation torque applied to the other side member is smaller than the inner holding torque, the other side member does not rotate but is held by the inner holding torque.

[0005] That is, in the conventional bidirectional torque limiter, the magnitude of the rotational torque at which slipping, i.e., rotation, starts when the rotational torque is transmitted from one member to the other member and when the rotational torque is transmitted from the other member to the one member is different, and the former is set smaller than the latter. Prior Art Literature Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6967687 Summary of the invention Technical problem to be solved by the invention

[0007] Furthermore, in the bidirectional torque limiter shown in the above-mentioned patent document 1, the number of parts is large, and there is room for improvement in assembly process, weight, and further cost. In addition, when the inner hook of the inner coil spring mounted on the outer circumferential surface of the inner ring is inserted into the hook groove formed on the inner circumferential surface of the outer ring, it is necessary to perform alignment, and the assembly process is complicated.

[0008] The present invention has been made in view of the above circumstances, and a main technical problem thereof is to review the structure of the conventional bidirectional torque limiter and provide a new bidirectional torque limiter having a smaller number of parts and easier assembly than the conventional bidirectional torque limiter. Technical solutions for solving technical problems

[0009] According to the present invention, as a bidirectional torque limiter for solving the above-mentioned main technical problems, there is provided a bidirectional torque limiter, comprising: a fixed housing; a one-side member; a second-side member; and a cylindrical ring member, wherein the one-side member, the second-side member, and the cylindrical ring member have a common central axis in the housing, A one-side locking piece extending in the axial direction is formed on the one-side member, and another-side locking piece extending in the axial direction is formed on the other-side member, and the one-side locking piece and the other-side locking piece are combined and arranged in a manner that two gaps exist in the circumferential direction. An inner coil spring is installed on the inner circumferential surface of the ring member. The outer diameter of the inner coil spring in a free state is larger than the inner diameter of the ring member, so that the inner coil spring is tightly attached to the ring member with a relatively small force. The inner coil spring has two inner hooks at different angular positions in the circumferential direction. The two inner hooks are respectively inserted into the two gaps. An outer coil spring is installed on the outer circumferential surface of the ring member. The inner diameter of the outer coil spring in a free state is smaller than the outer diameter of the ring member, so that the outer coil spring is tightly attached to the ring member with a relatively large force. The outer coil spring has two outer hooks at different angular positions in the circumferential direction. The two outer hooks are respectively inserted into recesses formed on the inner circumferential surface of the housing. When a rotational torque is applied to the one side member, one of the two inner hooks is pressed by the one side locking piece in the direction of the inner coil spring expanding in diameter, and one of the two outer hooks is pressed by the housing in the concave portion in the direction of the outer coil spring expanding in diameter, so that the one side member is integrated with the inner coil spring and the ring member, and rotates while overcoming the relatively large braking torque generated by the outer coil spring, and transmits the rotation to the other side member. On the other hand, if a rotational torque is applied to the other side member, any one of the two inner hooks is pressed by the other side locking piece in the direction of reducing the diameter of the inner coil spring, and any one of the two outer hooks is pressed by the housing in the recess in the direction of expanding the diameter of the outer coil spring. When the ring member is held by the outer coil spring, the other side member overcomes the relatively small braking torque generated by the inner coil spring and rotates relative to the ring member together with the inner coil spring, thereby transmitting the rotation to the one side member.

[0010] Preferably, the cross-sections of the one-side locking piece and the other-side locking piece are both arc-shaped extending around the central axis. In this case, notches are respectively formed at the circumferential ends of the axial ends of the one-side locking piece, and the circumferential end face of the one-side locking piece is divided into a notch end face formed with the notch and a non-notch end face without the notch. When the one-side member rotates, the notch end face presses any one of the two inner hooks, and the non-notch end face presses the circumferential end face of the other-side locking piece, and any one of the two inner hooks pressed by the notch end face is separated from the circumferential end face of the other-side locking piece. On the other hand, when the other-side member rotates, the circumferential end face of the other-side locking piece and any one of the two inner hooks press the non-notch end face of the one-side member together, and any one of the two inner hooks pressed by the other-side locking piece is separated from the notch end face of the one-side locking piece. The housing may be provided with an annular groove for clearance fit of both axial ends of the ring member. Preferably, the one side member, the other side member, the ring member, the inner coil spring and the outer coil spring are made of metal, and the housing is made of synthetic resin.

[0011] In addition, the above-mentioned main technical problems can also be solved by a bidirectional torque limiter, which includes: a fixing member; a one-side member; a second-side member; and a cylindrical ring member, wherein the one-side member, the second-side member, and the cylindrical ring member have a common central axis. A one-side locking piece extending in the axial direction is formed on the one-side member, and another-side locking piece extending in the axial direction is formed on the other-side member, and the one-side locking piece and the other-side locking piece are combined and arranged in a manner that two gaps exist in the circumferential direction. An outer coil spring is installed on the outer circumferential surface of the ring member, and the inner diameter of the outer coil spring in a free state is smaller than the outer diameter of the ring member, so that the outer coil spring is tightly attached to the ring member with a relatively small force, and the outer coil spring has two outer hooks at different angular positions in the circumferential direction, and the two outer hooks are respectively inserted into the two gaps. An inner coil spring is installed on the inner circumferential surface of the ring member. The outer diameter of the inner coil spring in a free state is larger than the inner diameter of the ring member, so that the inner coil spring is tightly attached to the ring member with a relatively large force. The inner coil spring has two inner hooks at different angular positions in the circumferential direction. The two inner hooks are respectively freely locked with the locking units provided on the fixing member. When a rotational torque is applied to the one side member, one of the two outer hooks is pressed by the one side locking piece in the direction of the outer coil spring reducing its diameter, and one of the two inner hooks is pressed by the locking unit in the direction of the inner coil spring reducing its diameter, so that the one side member becomes one with the outer coil spring and the ring member, and rotates while overcoming the relatively large braking torque generated by the inner coil spring, and transmits the rotation to the other side member. On the other hand, if a rotational torque is applied to the other side member, any one of the two outer hooks is pressed by the other side locking piece in the direction of the outer coil spring expanding in diameter, and any one of the two inner hooks is pressed by the locking unit in the direction of the inner coil spring shrinking in diameter. When the ring member is held by the inner coil spring, the other side member overcomes the relatively small braking torque generated by the outer coil spring and rotates relative to the ring member together with the outer coil spring, thereby transmitting the rotation to the one side member. Effects of the Invention

[0012] In the bidirectional torque limiter of the present invention, the inner coil spring and the outer coil spring are respectively installed on the inner circumference and the outer circumference of a common ring member. On the other hand, in the existing bidirectional torque limiter, the inner coil spring is installed on the outer circumference of the inner ring, and the outer coil spring is installed on the outer circumference of the outer ring, that is, the inner coil spring and the outer coil spring are respectively installed on the outer circumference of two different ring members. The ring member in the bidirectional torque limiter of the present invention is formed by integrating the inner ring and the outer ring in the existing bidirectional torque limiter. Therefore, according to the bidirectional torque limiter of the present invention, the number of components can be reduced by 1 compared with the existing bidirectional torque limiter. Furthermore, in the bidirectional torque limiter of the present invention, since there is no need for alignment between the outer coil spring and the inner coil spring and the ring member, the assembly process can be simplified. In the case of the existing bidirectional torque limiter, it is necessary to align the inner coil spring with the outer ring separately.

[0013] It should be noted that as a bidirectional torque limiter in which the inner coil spring and the outer coil spring are respectively mounted on the inner circumferential surface and the outer circumferential surface of a common ring member, there is a bidirectional torque limiter shown in Japanese Patent Publication No. 2002-155973, which was applied for and disclosed by the applicant of the present application before the present application (hereinafter referred to as "reference bidirectional torque limiter"). However, the reference bidirectional torque limiter changes the magnitude of the rotation torque that starts to rotate by forward and reverse rotation, which is completely different from the bidirectional torque limiter of the present invention and the existing bidirectional torque limiter shown in the above-mentioned patent document 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing the structure of a bidirectional torque limiter constructed according to the present invention. Figure 2 Yes Figure 1 The bidirectional torque limiter shown is disassembled and arranged according to each component. Figure 3 Remove the shield to indicate Figure 1 Figure 2 shows the internal structure of the bidirectional torque limiter. Figure 4 It is expressed as a monomer Figure 1 A diagram of the housing of a bi-directional torque limiter is shown. Figure 5 It is expressed as a monomer Figure 1 A diagram of one side member of a bi-directional torque limiter is shown. Figure 6 It is expressed as a monomer Figure 1 A diagram of the other side components of the bidirectional torque limiter is shown. Figure 7 It means in Figure 1 FIG. 1 is a diagram showing a state in which a rotation torque is applied to one side member of the bidirectional torque limiter shown. Figure 8 It means in Figure 1 FIG. 1 is a diagram showing a state in which a rotational torque is applied to the other side member in the bidirectional torque limiter shown. Fig. 9 It is a diagram showing a modified example of the bidirectional torque limiter configured according to the present invention. DETAILED DESCRIPTION

[0015] Hereinafter, a bidirectional torque limiter according to the present invention will be described in more detail with reference to the accompanying drawings showing preferred embodiments thereof.

[0016] Reference Figures 1 to 3 To explain, the bidirectional torque limiter generally indicated by reference numeral 2 includes: a fixed housing 4 ; a one-side member 6 ; a second-side member 8 ; and a ring member 10 , wherein the one-side member 6 , the second-side member 8 , and the ring member 10 have a common central axis o in the housing 4 .

[0017] and Figures 1 to 3 Together, refer to Figure 4 For explanation, the housing 4 includes Figure 4 The housing body 12 shown in (a) and Figure 4(b) shows the shield 14. In the illustrated embodiment, the housing body 12 and the shield 14 are each integrally formed of a suitable synthetic resin. The housing body 12 includes a circular end plate 16 arranged perpendicularly to the axial direction, and a cylindrical outer peripheral wall 18 extending from the outer peripheral edge of the end plate 16 to one side in the axial direction. A bulging portion 20 with a circular cross section bulging to the other side in the axial direction is formed in the central portion of the end plate 16. A circular recess 22 is provided in the center of one axial side surface of the bulging portion 20, and a circular hole 24 is formed in the center of the circular bottom surface of the recess 22 that passes through in the axial direction. There is a residual protrusion 26 in the shape of an annulus surrounding the outer peripheral edge of the recess 22 on one axial side surface of the end plate 16, a circular recess 28 is provided on the inner side of the residual protrusion 26, and a circular groove 30 is provided on the outer side. Six arc-shaped protrusions 32 protruding in the axial direction are arranged at equal angular intervals in the circumferential direction on the outer peripheral edge portion of the other axial side surface of the end plate 16. The housing 4 is fixed to a wall or the like not shown in the figure via a protrusion 32. On the inner circumferential surface of the outer circumferential wall 18, a plurality of (six in the illustrated embodiment) arc-shaped recesses 34 formed by locally increasing the inner diameter are formed at intervals in the circumferential direction. The recesses 34 extend in the axial direction. The circumferential lengths of the plurality of recesses 34 are not necessarily the same and can be appropriately changed. A step portion 36 extending in the circumferential direction is formed at the axially extending end portion of the inner circumferential surface of the outer circumferential wall 18 in the circumferential angular region where the recesses 34 are not formed. On the axially extending end surface of the outer circumferential wall 18, a plurality of (six in the illustrated embodiment) arc-shaped extension pieces 38 extending further in the axial direction continuously toward one side of the axial direction are formed at equal angular intervals in the circumferential direction. In the illustrated embodiment, the extension piece 38 roughly corresponds to the circumferential angular region where the recesses 34 are formed. A locking protrusion 40 extending in the circumferential direction is formed at the axially extending end portion of the inner circumferential surface of the extension piece 38.

[0018] The shield 14 includes a disc-shaped support wall 42 arranged perpendicularly to the axial direction, and a cylindrical mounting wall 44 extending from the outer peripheral edge of the support wall 42 to one side in the axial direction. A circular hole 46 is formed in the center of the support wall 42 and penetrates in the axial direction. An outer ring-shaped outer protrusion 48 and an inner protrusion 50 are formed on the outer peripheral edge of the other axial side of the support wall 42, and an annular groove 51 is provided between the outer protrusion 48 and the inner protrusion 50. The outer diameter of the mounting wall 44 is larger than the outer diameter of the support wall 42. A convex portion 52 in the shape of an arc formed by partially increasing the outer diameter is formed on the outer peripheral surface of the mounting wall 44. A plurality of convex portions 52 are formed corresponding to the number of extension pieces 38 formed on the housing body 12, so six convex portions 52 are formed in the illustrated embodiment, and the plurality of convex portions 52 are arranged at equal angles in the circumferential direction. The circumferential interval between two adjacent convex portions 52 in the circumferential direction corresponds to the circumferential length of the extension piece 38. A circumferentially extending retained protrusion 54 is formed on the outer peripheral surface of the mounting wall 44 between two circumferentially adjacent protrusions 52. When the shield 14 is mounted on the housing body 12, after the extension piece 38 of the housing body 12 is aligned between the two circumferentially adjacent protrusions 52, the shield 14 is forced to move in the axial direction toward the end plate 16 of the housing body 12, and the retained protrusion 54 elastically passes over the retaining protrusion 40 of the extension piece 38. When the shield 14 is mounted on the housing body 12, the outer peripheral edge of the support wall 42 of the shield 14 abuts against the step portion 36 of the housing body 12, and the protrusion 52 of the shield 14 abuts against the axial end surface (excluding the extension piece 38) of the outer peripheral wall 18 of the housing body 12.

[0019] and Figures 1 to 3 Together, refer to Figure 5 The description will be continued. In the illustrated embodiment, the one side member 6 is made of metal and is integrally formed based on powder metallurgy. The one side member 6 includes a cylindrical one side connection portion 56 connected to one of the external devices on the driving side and the driven side (the external device is not shown), and a one side locking piece 58 attached to the outer peripheral surface of the one side connection portion 56. The one side connection portion 56 is axially penetrated, and a sawtooth-like connecting internal tooth 60 is formed on the inner peripheral surface. Figure 1As shown in the AA cross-sectional view, one axial end portion of the one side connection portion 56 is fitted into and rotatably supported by a recess 22 formed in the end plate 16 of the shell body 12. The one side locking piece 58 extends from the axial middle portion of the outer peripheral surface of the one side connection portion 56 to the other axial side beyond the other axial end of the one side connection portion 56. The cross section of the one side locking piece 58 is an arc shape extending around the central axis o. A notch 62 and a notch 64 are respectively formed at the circumferential end portions of the axial side ends of the one side locking piece 58, and the circumferential end surface of the one side locking piece 58 is divided into a notch end surface 65a formed with the notch 62 or the notch 64, and a non-notch end surface 65b without the notch 62 or the notch 64. In the illustrated embodiment, the notch 62 is formed only at Figure 5 In the clockwise downstream end of the left figure, the cutout 64 is formed only at Figure 5 Therefore, when viewed from one side in the axial direction, the notch 62 and the notch 64 are located on opposite sides in the circumferential direction.

[0020] and Figures 1 to 3 Together, refer to Figure 6 The description continues. In the illustrated embodiment, the other side member 8 is also made of metal and is integrally formed based on powder metallurgy. The other side member 8 includes a cylindrical other side connection portion 66 connected to the other of the external devices on the driving side and the driven side (the external device is not shown), a disc-shaped middle portion 68 connected to one axial end of the other side connection portion 66, and an other side locking piece 70 attached to the outer peripheral surface of the middle portion 68. The other side connection portion 66 and the middle portion 68 penetrate together in the axial direction. Saw-like connecting external teeth 72 are formed on the outer peripheral surface of the other side connection portion 66. As Figure 1 As shown in the AA cross-sectional view, the middle portion 68 is arranged in the hole 46 formed in the support wall 42 of the shield 14 to axially support the one side connection portion 56 of the one side member 6. The other side locking piece 70 extends axially to one side from the axial middle portion of the outer peripheral surface of the middle portion 68 beyond the axial one side end of the middle portion 68. The cross section of the other side locking piece 70 is an arc shape extending around the central axis o. Although it is not necessary to clearly show it in the figure, the axial other side end surface of the other side locking piece 70 is opposite to the support wall 42 of the shield 14, thereby preventing the one side member 6 and the other side member 8 from moving axially and falling off from the housing 4. Here, by referring to Figure 3 It can be understood that the one-side locking piece 58 and the other-side locking piece 70 are combined and arranged so that two gaps 74 a and 74 b exist in the circumferential direction.

[0021] Reference Figures 1 to 3 In the illustrated embodiment, the ring member 10 is made of metal and is a cylindrical rigid body having a required axial width and radial thickness (plate thickness). Figure 1As shown in the AA cross-sectional view, one axial end of the ring member 10 is engaged with the annular groove 30 formed on the end plate 16 of the shell body 12, and the other axial end of the ring member 10 is engaged with the annular groove 51 formed on the supporting wall 42 of the shield 14 (clearance fit), and the ring member 10 is supported by the shell 4 from both axial sides.

[0022] An inner coil spring 76 is mounted on the inner peripheral surface of the ring member 10. Figure 3 In order to facilitate understanding, the inner coil spring 76 is marked with dots (in the following Figure 7 as well as Figure 8 The same also applies to the inner coil spring 76. In the illustrated embodiment, the inner coil spring 76 is formed of a metal wire having a rectangular cross-section. The inner coil spring 76 includes an inner winding portion 78 obtained by winding the wire into a spiral shape, and two inner hook portions 80a, 80b obtained by bending the wire radially inward at both axial ends of the inner coil portion 78. The outer diameter of the inner coil spring 76 in a free state, i.e., the outer diameter of the inner winding portion 78, is larger than the inner diameter of the ring member 10, so that the inner coil spring 76 is tightly attached to the ring member 10 with a relatively small force. In a state where the inner coil spring 76 is mounted on the ring member 10 and no force is applied to any of the two inner hook portions 80a, 80b, if the torque generated by the tight contact between the inner coil spring 76 and the ring member 10 is called an inner retaining torque, then the inner retaining torque is relatively small. The two inner hook portions 80a, 80b are arranged at different angular positions in the circumferential direction, such as Figure 3 As shown, the two inner hooks 80a and 80b are inserted into the two gaps 74a and 74b, respectively. Lubricant is applied to the inner coil spring 76.

[0023] In addition, an outer coil spring 82 is attached to the outer peripheral surface of the ring member 10. Figure 3 In order to facilitate understanding, the outer coil spring 82 is also marked with dots (in the following Figure 7 as well as Figure 8The same is true in the embodiment shown in the figure. The outer coil spring 82 is located at a position aligned with the inner coil spring 76 in the axial direction. The outer coil spring 82 is also composed of a metal wire having a rectangular cross section. The outer coil spring 82 includes an outer winding portion 84 obtained by winding the wire into a spiral shape, and two outer hooks 86a, 86b obtained by bending the wire toward the radial outer side at both axial ends of the outer coil portion 84. The winding direction of the wire observed from one side of the axial direction of the inner coil spring 76 and the outer coil spring 82 is the same. The inner diameter of the outer coil spring 82 in the free state, that is, the inner diameter of the outer coil portion 84 is smaller than the outer diameter of the ring member 10, so that the outer coil spring 82 is closely attached to the ring member 10 with a relatively large force. In a state where the outer coil spring 82 is installed on the ring member 10 and does not act on any of the two outer hooks 86a, 86b, if the torque generated by the close contact between the outer coil spring 82 and the ring member 10 is called the outer retaining torque, then the outer retaining torque is relatively large. The two outer hooks 86a, 86b are arranged at different angular positions in the circumferential direction, such as Figure 3 As shown, the two outer hooks 86a and 86b are respectively inserted into two of the plurality of recesses 34 formed on the inner peripheral surface of the outer peripheral wall 18 of the housing body 12. The outer coil spring 82 is also coated with a lubricant.

[0024] Next, the operation of the bidirectional torque limiter 2 will be described. First, refer to Figure 1 , Figure 3 as well as Figure 7 , from the external device on the one side not shown in the figure, in a clockwise direction (from Figure 1) is observed from the right side of the AA section view. The following is the same as above) to describe the case where a rotational torque is applied to one side member 6. In this case, one side locking piece 58 rotates in the clockwise direction and its circumferential end surface (more specifically, the circumferential end surface on the downstream side in the clockwise direction) presses the inner hook 80a of the inner coil spring 76 in the clockwise direction. In the illustrated embodiment, the cut end surface 65a presses the inner hook 80a. Since the outer coil spring 82 is also installed on the outer circumferential surface of the ring member 10 on which the inner coil spring 76 is installed, if the inner hook 80a is pressed in the clockwise direction and the ring member 10 intends to rotate in the clockwise direction together with the inner coil spring 76, the outer hook 86a is pressed in the counterclockwise direction by the housing 4 in the recess 34. Here, if the inner hook 80a is pressed in the clockwise direction, the inner coil spring 76, i.e., the inner winding portion 78, is enlarged in diameter, and the close contact between the outer circumference of the inner winding portion 78 and the inner circumference of the ring member 10 is enhanced. Therefore, the ring member 10 intends to rotate in the clockwise direction as one with the inner coil spring 76. On the other hand, if the outer hook 86a is pressed in the counterclockwise direction, the outer coil spring 82, i.e., the outer winding portion 84, is enlarged in diameter, and the close contact between the inner circumference of the outer winding portion 84 and the outer circumference of the ring member 10 is weakened. Therefore, in the case where the above-mentioned rotation torque applied to the one side member 6 is greater than the relatively large outer retaining torque, the ring member 10 slides relative to the outer coil spring 82. That is, in the state where the outer coil spring 82 is retained in the housing 4, the ring member 10 starts to rotate relative to the outer coil spring 82, and the one side member 6, the inner coil spring 76 and the ring member 10 become one and start to rotate in the clockwise direction. Then, after the non-cut end surface 65b of the one side locking piece 58 abuts against the circumferential end surface (more specifically, the circumferential end surface on the upstream side in the clockwise direction) of the other side locking piece 70, Figure 7 As shown, the one side member 6, the inner coil spring 76 and the ring member 10 rotate clockwise as a whole along with the other side member 8. That is, the clockwise rotation applied to the one side member 6 is transmitted to the other side member 8. At this time, the inner hook portion 80a is separated from the circumferential end surface of the other side locking piece 70. It should be noted that, when the above-mentioned rotation torque applied to the one side member 6 is smaller than the relatively large outer retaining torque, the one side member 6 does not rotate but is retained by the outer retaining torque.

[0025] When the one side member 6 rotates counterclockwise, except that the one side locking piece 58 presses the inner hook 80b of the inner coil spring 76 and the housing 4 presses the outer hook 86b of the outer coil spring 82, it is the same as the case where the one side member 6 rotates clockwise, so detailed description is omitted. It should be noted that in this case, the inner hook 80b and the outer hook 86b are also pressed in the direction in which the diameter of each coil spring is expanded. In addition, the magnitude of the torque at which the ring member 10 starts to rotate relative to the outer coil spring 82 is the same as the magnitude of the torque when the one side member 6 rotates clockwise.

[0026] Next, refer to Figure 1 , Figure 3 as well as Figure 8 , the case where a rotation torque is applied to the other side member 8 in the counterclockwise direction from the above-mentioned other side external device not shown in the figure is described. In this case, the other side locking piece 70 rotates in the counterclockwise direction and its circumferential end surface (more specifically, the circumferential end surface on the downstream side in the counterclockwise direction) presses the inner hook 80a of the inner coil spring 76 in the counterclockwise direction. Since the outer coil spring 82 is also installed on the outer circumferential surface of the ring member 10 on which the inner coil spring 76 is installed, if the inner hook 80a is pressed in the counterclockwise direction and the ring member 10 intends to rotate in the counterclockwise direction together with the inner coil spring 76, the outer hook 86b is pressed in the clockwise direction by the housing 4 in the recess 34. Here, if the inner hook 80a is pressed in the counterclockwise direction, the inner coil spring 76, that is, the inner winding portion 78 is reduced in diameter, and the close contact between the outer circumferential surface of the inner winding portion 78 and the inner circumferential surface of the ring member 10 is weakened. Furthermore, if the outer hook portion 86b is pressed in the clockwise direction, the outer coil spring 82, i.e., the outer winding portion 84, is expanded in diameter, and the close contact between the inner circumference of the outer winding portion 84 and the outer circumference of the ring member 10 is weakened. Therefore, in a case where the above-mentioned rotational torque applied to the one side member 6 is greater than the relatively small inner retaining torque, the inner coil spring 76 slides relative to the ring member 10. That is, in a state where the ring member 10 is retained by the outer coil spring 82, the inner coil spring 76 starts to rotate relative to the ring member, and the other side member 8 becomes one with the inner coil spring 76 and starts to rotate counterclockwise. Afterwards, as Figure 8As shown, the circumferential end surface of the other side locking piece 70 (more specifically, the circumferential end surface on the downstream side in the counterclockwise direction) and the inner hook 80a abut against the non-cut end surface 65b of the one side member 6 (the non-cut end surface 65b is located on the upstream side in the counterclockwise direction) and press them in the counterclockwise direction, and the other side member 8 and the inner coil spring 76 rotate in the counterclockwise direction as a whole along with the one side member 6. That is, the counterclockwise rotation applied to the other side member 8 is transmitted to the one side member 6. At this time, the inner hook 80a separates from the cut end surface 65a of the one side locking piece 58. It should be noted that, when the above-mentioned rotation torque applied to the other side member 8 is smaller than the relatively small inner holding torque, the other side member 8 does not rotate but is held by the inner holding torque.

[0027] When the other side member 8 rotates in the clockwise direction, except that the other side locking piece 70 presses the inner hook 80b of the inner coil spring 76 and the housing 4 presses the outer hook 86a of the outer coil spring 82, it is the same as the case where the other side member 8 rotates in the counterclockwise direction, so detailed description is omitted. It should be noted that in this case, the inner hook 80b is also pressed in the direction of the inner coil spring 76 to reduce the diameter, and the outer hook 86a is also pressed in the direction of the outer coil spring 82 to expand the diameter. In addition, the magnitude of the torque at which the inner coil spring 76 starts to rotate relative to the ring member 10 is the same as the magnitude of the torque when the other side member 8 rotates in the counterclockwise direction.

[0028] That is, in the bidirectional torque limiter 2, the magnitude of the rotational torque that starts sliding, i.e., starts rotating, when the rotational torque is transmitted from the one side member 6 to the other side member 8 and when the rotational torque is transmitted from the other side member 8 to the one side member 6 is different, and the former is set to be larger than the latter. Therefore, for example, if a hatchback as a driven side external device is connected to the one side connection portion 56 of the one side member 6, and an electric motor as a driving side external device is connected to the other side connection portion 66 of the other side member 8, the electric motor can open and close the hatchback with a relatively light load, and on the other hand, when the hatchback is in a fully open or intermediate angle position, the angle position of the hatchback is maintained without shaking under a relatively light load caused by interference such as wind. Therefore, the bidirectional torque limiter involved in the present invention can also be used as an angle position holding device.

[0029] In the bidirectional torque limiter having such properties, in the bidirectional torque limiter of the present invention, since the inner coil spring 76 and the outer coil spring 82 are respectively mounted on the inner circumferential surface and the outer circumferential surface of the common ring member 10, the number of components can be reduced by one, compared with the case where the inner coil spring and the outer coil spring are respectively mounted on the outer circumferential surfaces of two different ring members (inner ring and outer ring) as in the conventional bidirectional torque limiter. Furthermore, in the bidirectional torque limiter of the present invention, since the outer coil spring and the inner coil spring do not need to be aligned with the ring member, the assembly process can be simplified. In the case of the conventional bidirectional torque limiter, it is necessary to align the inner coil spring with the outer ring separately.

[0030] Furthermore, in the illustrated embodiment, although the one side member 6, the other side member 8, the ring member 10, the inner coil spring 76, and the outer coil spring 82 are made of metal, the housing 4 is made of synthetic resin. Therefore, when the one side locking piece 58 and the other side locking piece 70 abut against the inner hook 80a or the inner hook 80b of the inner coil spring 76, a sound is generated due to the collision between the metals, but when the outer hook 86a or the outer hook 86b of the outer coil spring 82 abuts against the housing 4, almost no sound is generated due to the collision between the metal and the synthetic resin. In the case where the housing 4 is made of metal, the above-mentioned sound generated during operation becomes too loud, together with the sound when the outer hook 86a or the outer hook 86b collides with the housing 4. Although it is not impossible to make the one side member and the other side member made of synthetic resin, these members are connected to external members, so relatively high strength is required, and it is preferably made of metal, especially formed by powder metallurgy.

[0031] In addition, in the illustrated embodiment, when one side member 6 rotates, the cut end face 65a presses any one of the two inner hooks 80a, 80b, and the non-cut end face 65b presses the circumferential end face of the other side locking piece 8, and any one of the two inner hooks 80a, 80b pressed by the cut end face 65a is separated from the circumferential end face of the other side locking piece 70. On the other hand, when the other side member 8 rotates, the circumferential end face of the other side locking piece 70 presses the non-cut end face 65b of the one side member 6 together with any one of the two inner hooks 80a, 80b, and any one of the two inner hooks 80a, 80b pressed by the other side locking piece 70 is separated from the cut end face 65a of the one side locking piece 58. That is, even when a rotational torque is applied from either one of the one-side member 6 and the other-side member 8, the inner hooks 80a and 80b are not clamped by the circumferential end surfaces of the one-side locking piece 58 and the other-side locking piece 70, and the inner hooks 80a and 80b are not located on the transmission path of the rotational torque from the one-side member 6 to the other-side member 8 or in the opposite direction. Therefore, it is avoided that the force is concentrated on the inner hooks 80a and 80b when the above-mentioned rotational torque is applied, and the damage of the inner hooks 80a and 80b is prevented.

[0032] Although the bidirectional torque limiter according to the present invention has been described in detail with reference to the accompanying drawings, the present invention is not limited to the above-mentioned embodiment and can be appropriately modified and changed without departing from the scope of the present invention. For example, in the above-mentioned embodiment, the two inner hooks 80a and 80b of the inner coil spring 76 are respectively inserted into the two gaps 74a and 74b generated when the one-side locking piece 58 and the other-side locking piece 70 are combined, but instead, the two outer hooks of the outer coil spring can be respectively inserted. Fig. 9 Such a modified example will be described. Fig. 9 is equivalent to Figure 3 Figure. Fig. 9 In Figure 3The same structure is indicated by marking the same number with "'", and its detailed description is omitted. In this modified example, the outer coil spring 82' is made to be in close contact with the ring member 10' with a force smaller than that of the inner coil spring 76'. A locking unit 88' with a cross-sectional arc shape extending linearly in the axial direction is formed in the center of the housing 4' as a fixed member (so that the locking unit 88' is fixed), and the inner coil spring 76' is arranged along the outer circumferential surface of the locking unit 88'. In addition, when a rotational torque is applied to either one of the side member 6' and the other side member 8' and the inner coil spring 76' intends to rotate together with the ring member 10', any one of the two inner hooks 80a', 80b' is pressed by the locking unit 88', or more specifically, by its circumferential end surface in the direction of the reduction of the diameter of the inner coil spring 76'. Therefore, if a rotational torque is applied to one side member 6', any one of the two outer hooks 86a', 86b' is pressed by the one side locking piece 58' in the direction of reducing the diameter of the outer coil spring 82', and any one of the two inner hooks 80a', 80b' is pressed by the locking unit 88' in the direction of reducing the diameter of the inner coil spring 76', and the one side member 6' becomes one with the outer coil spring 82' and the ring member 10', and rotates to overcome the relatively large braking torque generated by the inner coil spring 76', and transmits the rotation to the other side member 8'. On the other hand, if a rotation torque is applied to the other side member 8', any one of the two outer hooks 86a', 86b' is pressed by the other side locking piece 70' in the direction of the outer coil spring 82' expanding in diameter, and any one of the two inner hooks 80a', 80b' is pressed by the locking unit 88' in the direction of the inner coil spring 76' contracting in diameter, and in the state where the ring member 10' is held by the inner coil spring 76', the other side member 8' overcomes the relatively small braking torque generated by the outer coil spring 82' and rotates relative to the ring member 10' together with the outer coil spring 82', and transmits the rotation to the one side member 6'. It should be noted that in this modification, if the locking unit 88' is fixed, it does not necessarily need to be arranged on the housing 4', so the housing 4' can also be omitted. In the case where the housing 4' is omitted, the locking unit 88' itself becomes a fixed member, or it is arranged on a part of another fixed member not shown.

[0033] In addition, although in the illustrated embodiment, the cross-sections of the one side locking piece and the other side locking piece are both arc-shaped extending around the central axis and are respectively composed of a single member, the one side locking piece and the other side locking piece can also be divided into two columnar members arranged at intervals in the circumferential direction. Depending on the use, etc., all the constituent members can also be made of synthetic resin or metal. Moreover, the cross-section of the wire material constituting the inner coil spring and the outer coil spring can also be circular instead of rectangular. Description of Reference Numerals

[0034] 2: Bidirectional torque limiter 4: Shell 6: One side member 8: The other side member 10: Ring component 34: Recess (of the housing) 58: One side stopper 70: The other side stopper 74a, 74b: Gap 76: Inner coil spring 80a, 80b: inner hook 82: Outer coil spring 86a, 86b: Outer hook.

Claims

1. A bidirectional torque limiter, comprising: a fixed housing; a one-side member; a second-side member; and a cylindrical ring member, wherein the one-side member, the second-side member, and the cylindrical ring member have a common central axis in the housing, A one-side locking piece extending in the axial direction is formed on the one-side member, and another-side locking piece extending in the axial direction is formed on the other-side member, and the one-side locking piece and the other-side locking piece are combined and arranged in a manner that two gaps exist in the circumferential direction. An inner coil spring is installed on the inner circumferential surface of the ring member. The outer diameter of the inner coil spring in a free state is larger than the inner diameter of the ring member, so that the inner coil spring is tightly attached to the ring member with a relatively small force. The inner coil spring has two inner hooks at different angular positions in the circumferential direction. The two inner hooks are respectively inserted into the two gaps. An outer coil spring is installed on the outer circumferential surface of the ring member. The inner diameter of the outer coil spring in a free state is smaller than the outer diameter of the ring member, so that the outer coil spring is tightly attached to the ring member with a relatively large force. The outer coil spring has two outer hooks at different angular positions in the circumferential direction. The two outer hooks are respectively inserted into recesses formed on the inner circumferential surface of the housing. When a rotational torque is applied to the one side member, one of the two inner hooks is pressed by the one side locking piece in the direction of the inner coil spring expanding in diameter, and one of the two outer hooks is pressed by the housing in the concave portion in the direction of the outer coil spring expanding in diameter, so that the one side member is integrated with the inner coil spring and the ring member, and rotates while overcoming the relatively large braking torque generated by the outer coil spring, and transmits the rotation to the other side member. On the other hand, if a rotational torque is applied to the other side member, any one of the two inner hooks is pressed by the other side locking piece in the direction of reducing the diameter of the inner coil spring, and any one of the two outer hooks is pressed by the housing in the recess in the direction of expanding the diameter of the outer coil spring. When the ring member is held by the outer coil spring, the other side member overcomes the relatively small braking torque generated by the inner coil spring and rotates relative to the ring member together with the inner coil spring, thereby transmitting the rotation to the one side member.

2. The bidirectional torque limiter according to claim 1, wherein: The cross sections of the one-side locking piece and the other-side locking piece are both arc-shaped extending around the central axis.

3. The bidirectional torque limiter according to claim 2, wherein: Notches are formed at the circumferential ends of both axial ends of the one side locking piece, respectively, and the circumferential end surface of the one side locking piece is divided into a notch end surface formed with the notch and a non-notch end surface without the notch. When the one side member rotates, the cut end face presses any one of the two inner hooks, and the non-cut end face presses the circumferential end face of the other side locking piece, and any one of the two inner hooks pressed by the cut end face is separated from the circumferential end face of the other side locking piece. On the other hand, when the other side member rotates, the circumferential end face of the other side locking piece presses the non-cut end face of the one side member together with any one of the two inner hooks, and any one of the two inner hooks pressed by the other side locking piece is separated from the cut end face of the one side locking piece.

4. The bidirectional torque limiter according to claim 1, wherein: The housing is provided with annular grooves in which both axial end portions of the ring member are loosely fitted.

5. The bidirectional torque limiter according to claim 1, wherein: The one side member, the other side member, the ring member, the inner coil spring, and the outer coil spring are made of metal, and the housing is made of synthetic resin.

6. A bidirectional torque limiter comprising: a fixing member; a one-side member; a second-side member; and a cylindrical ring member, wherein the one-side member, the second-side member, and the cylindrical ring member have a common central axis, A one-side locking piece extending in the axial direction is formed on the one-side member, and another-side locking piece extending in the axial direction is formed on the other-side member, and the one-side locking piece and the other-side locking piece are combined and arranged in a manner that two gaps exist in the circumferential direction. An outer coil spring is installed on the outer circumferential surface of the ring member, and the inner diameter of the outer coil spring in a free state is smaller than the outer diameter of the ring member, so that the outer coil spring is tightly attached to the ring member with a relatively small force, and the outer coil spring has two outer hooks at different angular positions in the circumferential direction, and the two outer hooks are respectively inserted into the two gaps. An inner coil spring is installed on the inner circumferential surface of the ring member. The outer diameter of the inner coil spring in a free state is larger than the inner diameter of the ring member, so that the inner coil spring is tightly attached to the ring member with a relatively large force. The inner coil spring has two inner hooks at different angular positions in the circumferential direction. The two inner hooks are respectively freely locked with the locking units provided on the fixing member. When a rotational torque is applied to the one side member, one of the two outer hooks is pressed by the one side locking piece in the direction of the outer coil spring reducing its diameter, and one of the two inner hooks is pressed by the locking unit in the direction of the inner coil spring reducing its diameter, so that the one side member becomes one with the outer coil spring and the ring member, and rotates while overcoming the relatively large braking torque generated by the inner coil spring, and transmits the rotation to the other side member. On the other hand, if a rotational torque is applied to the other side member, any one of the two outer hooks is pressed by the other side locking piece in the direction of the outer coil spring expanding in diameter, and any one of the two inner hooks is pressed by the locking unit in the direction of the inner coil spring shrinking in diameter. When the ring member is held by the inner coil spring, the other side member overcomes the relatively small braking torque generated by the outer coil spring and rotates relative to the ring member together with the outer coil spring, thereby transmitting the rotation to the one side member.

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