rotary damper

Abstract

To enable generation of a braking force when an engagement part turns toward a terminal point of a movable range of the engagement part while the engagement part is turning to a prescribed position from the terminal point in a rotary damper having a non-rotation zone of a rotating member.SOLUTION: A rotary damper (10) having a non-rotation zone (S1) of a rotating member (12) includes: first means for making a first engaged part (13) follow an engagement part (31) when the engagement part (31) turns from a terminal point (E) of a movable range (R) of the engagement part (31) to a prescribed position (P); and second means for stopping the following of the first engaged part (13) at the prescribed point (P).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotary damper. [Background technology]

[0002] Conventionally, a rotary damper has been known which includes a non-rotating member, a rotating member which rotates around the non-rotating member, a first engaged portion provided on the rotating member, and a second engaged portion provided on the rotating member with a gap between the first engaged portion and the second engaged portion, wherein an engaging portion which is installed between the first engaged portion and the second engaged portion and rotates together with a controlled object presses the first engaged portion, causing the rotating member to rotate in one direction, generating a braking force when the rotating member rotates in one direction, and wherein the rotating member has a non-rotating section while the engaging portion rotates from the start point of the movable range of the engaging portion to the end point of the movable range of the engaging portion.

[0003] For example, Patent Document 1 discloses a rotary damper comprising a non-rotating member (fixed-side damper 4b), a rotating member (movable-side damper 4a) that rotates around the non-rotating member, a first engaged portion (one end of a guide groove 7a) provided on the rotating member, and a second engaged portion (the other end of the guide groove 7a) provided on the rotating member with a gap between them, wherein an engaging portion (stopper member 6) that is installed between the first engaged portion and the second engaged portion and rotates together with a controlled object (seat back frame 1) presses the first engaged portion, causing the rotating member to rotate in one direction, and a braking force is generated when the rotating member rotates in one direction, and a non-rotating section of the rotating member is present (FIGS. 2(a), 2(b), and 3) of Patent Document 1 while the engaging portion rotates from the start point of the movable range of the engaging portion (FIG. 2(a) of Patent Document 1) to the end point of the movable range of the engaging portion (FIG. 2(c) of Patent Document 1).

[0004] However, in the rotary damper disclosed in Patent Document 1, when the engaging portion rotates from the end point toward the start point, the rotating member does not rotate until the engaging portion contacts the second engaged portion, so even if the engaging portion rotates toward the end point during this period, no braking force is generated by the rotary damper. Therefore, if the user releases their hand from the seat back during this period, the seat back will hit the seat cushion with great force, which is a problem. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2007-050765 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to make it possible to generate a braking force in a rotary damper having a non-rotating section of a rotating member when the engaging portion rotates toward a predetermined position from the end point of the movable range of the engaging portion. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides the following rotary damper. 1. A rotary damper comprising a non-rotating member, a rotating member that rotates around the non-rotating member, a first engaged portion provided on the rotating member, and a second engaged portion provided on the rotating member with a gap between the first engaged portion and the second engaged portion, wherein an engaging portion that is installed between the first engaged portion and the second engaged portion and rotates together with a controlled object presses the first engaged portion, causing the rotating member to rotate in one direction, and a braking force is generated when the rotating member rotates in one direction, and wherein the rotating member has a non-rotating section while the engaging portion rotates from the start point of the movable range of the engaging portion to the end point of the movable range of the engaging portion, and characterized by having first means for causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position, and second means for stopping the following of the first engaged portion at the predetermined position. 2. A rotary damper comprising a non-rotating member, a rotating member that rotates around the non-rotating member, a first engaged portion provided on the rotating member, and a second engaged portion provided on the rotating member with a gap between the first engaged portion and the second engaged portion, wherein an engaging portion that is installed between the first engaged portion and the second engaged portion and rotates together with a controlled object presses the first engaged portion, causing the rotating member to rotate in one direction, and a braking force is generated when the rotating member rotates in one direction, and wherein the rotating member has a non-rotating section while the engaging portion rotates from the start point of the movable range of the engaging portion to the end point of the movable range of the engaging portion, and wherein the rotary damper comprises a spring having a first function of causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position, and a second function of stopping the first engaged portion from following the engaging portion at the predetermined position. [Effects of the Invention]

[0008] According to the first aspect of the present invention, in a rotary damper having a non-rotating section of a rotating member while the engaging portion rotates from the start point of its movable range to the end point of its movable range, the rotary damper has first means for causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position, so that a braking force can be generated when the engaging portion rotates toward the end point while rotating from the end point to the predetermined position. Also, according to the first aspect of the present invention, the rotary damper has second means for stopping the following of the first engaged portion at the predetermined position, so that it is possible not to generate a braking force when the engaging portion rotates from the predetermined position to the starting point. According to the second aspect of the present invention, in a rotary damper having a non-rotating section of a rotating member while the engaging portion rotates from the start point of its movable range to the end point of its movable range, a spring having a first function of causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position is provided, so that a braking force can be generated when the engaging portion rotates toward the end point while rotating from the end point to the predetermined position.Furthermore, according to the second aspect of the present invention, because the spring has a second function of stopping the first engaged portion from following the first engaged portion at the predetermined position, it is also possible to not generate a braking force when the engaging portion rotates from the predetermined position to the starting point. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a state in which a rotary damper according to a first embodiment is installed on an automobile seat. [Figure 2] FIG. 2 is a diagram showing the internal structure of the rotary damper employed in the first embodiment. [Figure 3] FIG. 3 is a diagram showing the first means employed in the first embodiment. [Figure 4] FIG. 4 is an enlarged view of part A in FIG. [Figure 5] FIG. 5 is a diagram for explaining the operation of the rotary damper according to the first embodiment, showing a state in which the engagement portion is located at a predetermined position. [Figure 6] FIG. 6 is a diagram for explaining the operation of the rotary damper according to the first embodiment, showing a state in which the engagement portion is located at the end point of the rotation range of the engagement portion. [Figure 7] FIG. 7 is a diagram for explaining the operation of the rotary damper according to the first embodiment, showing a state in which the engagement portion is released from the groove. [Figure 8] FIG. 8 is a diagram showing the cap employed in the second embodiment. [Figure 9] FIG. 9 is a diagram showing a state in which the rotary damper according to the third embodiment is installed on an automobile seat. [Figure 10] FIG. 10 is a diagram showing the internal structure of the rotary damper employed in the third embodiment. [Figure 11] FIG. 11 is a diagram for explaining the operation of the rotary damper according to the third embodiment, showing a state in which the engagement portion is located at a predetermined position. [Figure 12] FIG. 12 is a diagram for explaining the operation of the rotary damper according to the third embodiment, showing a state in which the engagement portion is located at the end point of the rotation range of the engagement portion. [Figure 13] FIG. 13 is a diagram for explaining the operation of the rotary damper according to the third embodiment, showing a state in which the engaging portion is separated from the first engaged portion. [Figure 14] FIG. 4 is a diagram showing a state in which the rotary damper according to the fourth embodiment is installed on an automobile seat. [Figure 15] FIG. 15 is a diagram showing the internal structure of the rotary damper employed in the fourth embodiment. [Figure 16] FIG. 16 is a diagram for explaining the operation of the rotary damper according to the fourth embodiment, showing a state in which the engagement portion is located at a predetermined position. [Figure 17] FIG. 17 is a diagram for explaining the operation of the rotary damper according to the fourth embodiment, showing a state in which the engagement portion is located at the end point of the rotation range of the engagement portion. [Figure 18] FIG. 18 is a diagram for explaining the operation of the rotary damper according to the fourth embodiment, showing a state in which the engaging portion is separated from the first engaged portion. [Figure 19]FIG. 19 is a diagram illustrating an internal structure of the rotary damper according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. [Example]

[0011] Referring to FIG. 1 , a rotary damper 10 according to the first embodiment is installed in an automobile seat. The seat back of the automobile seat is an example of a controlled object 30. However, the controlled object 30 is not limited to this. The controlled object 30 has an engaging portion 31 that rotates together with the controlled object 30. In the first embodiment, a transmission shaft attached to the frame of the seat back is an example of the engaging portion 31. However, the engaging portion 31 is not limited to this.

[0012] In Figure 1, R is the movable range of the engagement portion 31, S is the starting point of the movable range R of the engagement portion 31, E is the end point of the movable range R of the engagement portion 31, P is a predetermined position, S1 is the non-rotating section of the rotating member 12, and S2 is the rotating section of the rotating member 12.

[0013] The predetermined position P is the position where the engaging portion 31, which rotates from the starting point S toward the end point E, first engages with the first engaged portion 13. The predetermined position P can be set arbitrarily by changing the arrangement of the vane 16. However, the predetermined position P is not the same position as the starting point S or the end point E. The non-rotation section S1 is a section where the rotating member 12 does not rotate due to the rotation of the engaging portion 31. The rotation section S2 is a section where the rotating member 12 rotates due to the rotation of the engaging portion 31.

[0014] Referring to Figure 2, the rotary damper 10 is configured to have a non-rotating member 11, a rotating member 12, a first engaged portion 13 provided on the rotating member 12, and a second engaged portion 14 provided on the rotating member 12 at a distance from the first engaged portion 13.

[0015] The non-rotating member 11 is a member that does not rotate when the rotary damper 10 is in use. The non-rotating member 11 is configured to have a shaft portion 15 that is connected to a shaft 32 that is the center of rotation of the controlled object 30, and a vane 16 that protrudes from the shaft portion 15. The vane 16 is installed in an oil chamber 17 that is formed around the shaft portion 15. Oil is poured into the oil chamber 17.

[0016] The rotating member 12 is a member that rotates around the non-rotating member 11 when the rotary damper 10 is in use. The rotating member 12 is configured to have a cylindrical peripheral wall 18 and a partition wall 19 that protrudes from the inner peripheral surface of the peripheral wall 18. The partition wall 19 is a partition that separates two oil chambers 17.

[0017] The first engaged portion 13 is a portion that engages with the engaging portion 31 when the engaging portion 31 rotates from the starting point S toward the end point E. In the first embodiment, the first protrusion that protrudes from the outer peripheral surface of the peripheral wall 18 is an example of the first engaged portion 13. However, the first engaged portion 13 is not limited to this.

[0018] The second engaged portion 14 is a portion that engages with the engaging portion 31 when the engaging portion 31 rotates from the end point E toward the start point S. In the first embodiment, the second protrusion that protrudes from the outer peripheral surface of the peripheral wall 18 at a distance from the first protrusion is an example of the second engaged portion 14. However, the second engaged portion 14 is not limited to this.

[0019] The distance between the first engaged portion 13 and the second engaged portion 14 is set so that the engaging portion 31 can rotate between the first engaged portion 13 and the second engaged portion 14. The non-rotation section S1 is determined by this distance.

[0020] The rotary damper 10 of Example 1 is further configured to have a first means for causing the first engaged portion 13 to follow the engaging portion 31 when the engaging portion 31 rotates from the end point E to a predetermined position P, and a second means for stopping the following of the first engaged portion 13 at the predetermined position P.

[0021] Referring to FIG. 3, the first means employed in the first embodiment is configured to have a groove 20 formed in the first engaged portion 13 and a claw 21 formed in the groove 20.

[0022] The groove 20 is formed in a U-shape, and has a width W and a depth D that can accommodate the engaging portion 31 within the groove 20. Two claws 21 are provided, and a distance S3 between a first claw 21 that protrudes from one side wall of the groove 20 toward the other side wall of the groove 20 that faces the first side wall and a second claw 21 that protrudes from the other side wall of the groove 20 toward the one side wall of the groove 20 is set shorter than the diameter of the engaging portion 31 to prevent the engaging portion 31 accommodated in the groove 20 from escaping.

[0023] Referring to FIG. 4, each of the two claws 21 has a slope 22 that makes it easier for the engagement portion 31 to enter the groove 20 .

[0024] The second means employed in the first embodiment is configured with vane 16 and partition wall 19 (see FIG. 2). Partition wall 19 moves within oil chamber 17 as rotating member 12 rotates, while vane 16 remains stationary in a fixed position. Therefore, when rotating member 12 rotates in the reverse direction (i.e., the direction opposite to the one direction), partition wall 19 comes into contact with vane 16 at a predetermined position P. This prevents rotating member 12 from rotating in the reverse direction. The position of vane 16 is set to correspond to the position where engaging portion 31 escapes from groove 20 (i.e., predetermined position P).

[0025] The rotary damper 10 according to the first embodiment operates as follows. That is, when the seat back (controlled object 30) is reclined (that is, when the seat back is moved closer to the seat cushion 33), the engaging portion 31 rotates from a start point S toward an end point E. Then, the engaging portion 31 engages with the first engaged portion 13 at a predetermined position P. Within the movable range R of the engaging portion 31, the section in which the engaging portion 31 rotates from the start point S to the predetermined position P is a non-rotation section S1 of the rotating member 12, and the rotating member 12 does not rotate. Therefore, in the non-rotation section S1, no braking force is generated by the rotary damper 10. In this way, the rotary damper 10 according to the first embodiment has the non-rotation section S1 of the rotating member 12 while the engaging portion 31 rotates from the start point S to the end point E.

[0026] When the engaging portion 31 and the first engaged portion 13 are engaged, the engaging portion 31 is accommodated in the groove 20 constituting the first means, as shown in FIG. 5. When the engaging portion 31 rotates toward the end point E in this state, the engaging portion 31 pushes the first engaged portion 13, causing the rotating member 12 to rotate in one direction. This rotation causes the partition wall 19 to move around the shaft portion 15 while being subjected to the resistance of the oil, so that the rotary damper 10 generates a braking force (i.e., a force that slows the rotation speed of the engaging portion 31) when the rotating member 12 rotates in one direction. As a result, the seat back collapses at a low speed (i.e., a speed slower than the speed at which the seat back collapses under its own weight) and comes into contact with the seat cushion 33. FIG. 6 shows the state in which the engaging portion 31 is positioned at the end point E.

[0027] When the engaging portion 31 rotates from the end point E to the predetermined position P, the first engaged portion 13 moves following the rotation of the engaging portion 31 because the claw 21 constituting the first means prevents the engaging portion 31 housed in the groove 20 constituting the first means from escaping from the groove 20. If the hand used to raise the seat back is released from the seat back while the engaging portion 31 is between the end point E and the predetermined position P, the engaging portion 31, which had been rotating toward the start point S, rotates toward the end point E, and the rotating member 12 rotates in one direction, generating a braking force. Therefore, with the rotary damper 10 according to the first embodiment, the seat back can be reclined at a low speed even if the hand is released from the seat back while the engaging portion 31 is between the end point E and the predetermined position P.

[0028] In addition, the rotary damper 10 employed in Example 1 generates a braking force even when the rotating member 12 rotates in the opposite direction when the engaging portion 31 rotates from the end point E to the predetermined position P, so the load when raising the seat back is large. To solve this problem, for example, an oil flow path may be formed in the vane 16 or the partition wall 19, and a check valve may be provided in the flow path to suppress the generation of the braking force, or the spring employed in Example 3 may be combined to reduce the load.

[0029] When engaging portion 31 rotates from predetermined position P to starting point S, partition wall 19 constituting second means comes into contact with vane 16 constituting second means at predetermined position P, causing vane 16 to prevent movement of partition wall 19, and engaging portion 31 escapes from groove 20, as shown in FIG. 7. In this manner, second means has the function of stopping first engaged portion 13 from following engaging portion 31 at predetermined position P. As described above, when engaging portion 31 escapes from groove 20, rotation of rotating member 12 in the reverse direction is stopped, so when engaging portion 31 rotates from predetermined position P to starting point S, i.e., in non-rotation section S1 of rotating member 12, no braking force is generated. [Example]

[0030] 8, the rotary damper 10 according to the second embodiment is configured to have a cap 23 that covers the first engaged portion 13. The second embodiment differs from the first embodiment in that the first means is formed in the cap 23.

[0031] That is, the first means employed in Example 2 is configured to have a groove 24 formed in cap 23 and a claw 25 formed in groove 24. Groove 24 has the function of accommodating engaging portion 31, and claw 25 has the function of preventing engaging portion 31 accommodated in groove 24 from escaping, which is the same as groove 20 and claw 21 in Example 1.

[0032] Similar to the first embodiment, the rotary damper 10 according to the second embodiment has first means (grooves 24 and pawls 25) for causing the first engaged portion 13 to follow the engaging portion 31 when the engaging portion 31 rotates from the end point E to the predetermined position P, and therefore generates a braking force when the engaging portion 31 rotates toward the end point E while the engaging portion 31 rotates from the end point E to the predetermined position P. Also, similar to the first embodiment, the rotary damper 10 according to the second embodiment has second means (vanes 16 and partition walls 19) for stopping the first engaged portion 13 from following at the predetermined position P, and therefore does not generate a braking force when the engaging portion 31 rotates from the predetermined position P to the start point S. [Example]

[0033] Referring to FIG. 9, a rotary damper 10 according to a third embodiment is installed in an automobile seat. The seat back of the automobile seat is an example of the controlled object 30. However, the controlled object 30 is not limited to this. The controlled object 30 has an engaging portion 31 that rotates together with the controlled object 30. In the third embodiment, a transmission shaft attached to the frame of the seat back is an example of the engaging portion 31. However, the engaging portion 31 is not limited to this.

[0034] 9, R is the movable range of the engaging portion 31, S is the start point of the movable range R of the engaging portion 31, E is the end point of the movable range R of the engaging portion 31, P is a predetermined position, S1 is a non-rotation section of the rotating member 12, and S2 is a rotation section of the rotating member 12. The definitions of the predetermined position P, the non-rotation section S1, and the rotation section S2 are the same as those explained in the first embodiment.

[0035] Referring to FIG. 10, the rotary damper 10 according to the third embodiment differs from the first embodiment in that the first means is configured to include a spring 26.

[0036] In this embodiment, a tension coil spring is used as the spring 26. However, the type of spring 26 is not limited to this. One end of the spring 26 is attached to the second engaged portion 14. However, the attachment location of the one end of the spring 26 is not limited to this. The other end of the spring 26 is attached to the frame of the seat cushion 33, as shown in FIG. 9. The frame of the seat cushion 33 is one example of the attachment location of the other end of the spring 26.

[0037] The spring 26 has a function of causing the first engaged portion 13 to follow the engaging portion 31 when the engaging portion 31 rotates from the end point E to a predetermined position P.

[0038] The rotary damper 10 according to the third embodiment operates as follows. That is, when the seat back (controlled object 30) is reclined, the engaging portion 31 rotates from a start point S toward an end point E. Then, the engaging portion 31 engages with the first engaged portion 13 at a predetermined position P. Within the movable range R of the engaging portion 31, the section in which the engaging portion 31 rotates from the start point S to the predetermined position P is a non-rotation section S1 of the rotating member 12, and the rotating member 12 does not rotate. Therefore, in the non-rotation section S1, no braking force is generated by the rotary damper 10. In this way, the rotary damper 10 according to the third embodiment has the non-rotation section S1 of the rotating member 12 while the engaging portion 31 rotates from the start point S to the end point E.

[0039] When the engaging portion 31 and the first engaged portion 13 engage with each other, the engaging portion 31 comes into contact with the first engaged portion 13, as shown in FIG. 11 . When the engaging portion 31 rotates toward the end point E in this state, the engaging portion 31 presses the first engaged portion 13, causing the rotating member 12 to rotate in one direction. This rotation causes the partition wall 19 to move around the shaft portion 15 while receiving resistance from the oil. Therefore, the rotary damper 10 generates a braking force when the rotating member 12 rotates in one direction. Furthermore, when the engaging portion 31 rotates toward the end point E while in contact with the first engaged portion 13, the spring 26 expands, storing elastic energy in the spring 26. As a result, the seat back reclines at a low speed and comes into contact with the seat cushion 33. FIG. 12 shows the state in which the engaging portion 31 is positioned at the end point E.

[0040] When the engaging portion 31 rotates from the end point E to the predetermined position P, the first engaged portion 13 moves following the rotation of the engaging portion 31 due to the restoring force (release of elastic energy) of the spring 26. If the hand used to raise the seat back is released from the seat back while the engaging portion 31 is present between the end point E and the predetermined position P, the engaging portion 31, which had been rotating toward the start point S, rotates toward the end point E, and the rotating member 12 rotates in one direction, generating a braking force. Therefore, with the rotary damper 10 according to the third embodiment, the seat back can be reclined at a low speed even if the hand is released from the seat back while the engaging portion 31 is present between the end point E and the predetermined position P.

[0041] The rotary damper 10 employed in the third embodiment generates a braking force even when the rotating member 12 rotates in the reverse direction when the engaging portion 31 rotates from the end point E to the predetermined position P. However, this braking force is neutralized or reduced by the restoring force of the spring 26, so the load when raising the seat back is reduced.

[0042] When engaging portion 31 rotates from predetermined position P to starting point S, partition wall 19 constituting second means comes into contact with vane 16 constituting second means at predetermined position P, causing vane 16 to prevent movement of partition wall 19, and engaging portion 31 moves away from first engaged portion 13, as shown in FIG. 13 . In this way, the second means has the function of stopping first engaged portion 13 from following engaging portion 31 at predetermined position P. As described above, when engaging portion 31 moves away from first engaged portion 13, rotation of rotating member 12 in the reverse direction is stopped, so when engaging portion 31 rotates from predetermined position P to starting point S, i.e., in non-rotation section S1 of rotating member 12, no braking force is generated. [Example]

[0043] Referring to FIG. 14 , a rotary damper 10 according to a fourth embodiment is installed in an automobile seat. The seatback of the automobile seat is an example of the controlled object 30. However, the controlled object 30 is not limited to this. The controlled object 30 has an engaging portion 31 that rotates together with the controlled object 30. In the fourth embodiment, a transmission shaft attached to the frame of the seatback is an example of the engaging portion 31. However, the engaging portion 31 is not limited to this.

[0044] 14, R is the movable range of the engaging portion 31, S is the start point of the movable range R of the engaging portion 31, E is the end point of the movable range R of the engaging portion 31, P is a predetermined position, S1 is a non-rotation section of the rotating member 12, and S2 is a rotation section of the rotating member 12. The definitions of the predetermined position P, the non-rotation section S1, and the rotation section S2 are the same as those explained in the first embodiment.

[0045] Referring to FIG. 15, the rotary damper 10 according to the fourth embodiment differs from the first embodiment in that it is configured to include a spring 26 in place of the first means and the second means.

[0046] In this embodiment, a tension coil spring is used as the spring 26. However, the type of spring 26 is not limited to this. One end of the spring 26 is attached to the second engaged portion 14. However, the attachment location of the one end of the spring 26 is not limited to this. The other end of the spring 26 is attached to the frame of the seat cushion 33, as shown in FIG. 14. The frame of the seat cushion 33 is one example of the attachment location of the other end of the spring 26.

[0047] The spring 26 has a first function of causing the first engaged portion 13 to follow the engaging portion 31 when the engaging portion 31 rotates from the end point E to a predetermined position P, and a second function of causing the first engaged portion 13 to stop following at the predetermined position P.

[0048] The rotary damper 10 according to the fourth embodiment operates as follows. That is, when the seat back (controlled object 30) is reclined, the engaging portion 31 rotates from a start point S toward an end point E. Then, the engaging portion 31 engages with the first engaged portion 13 at a predetermined position P. Within the movable range R of the engaging portion 31, the section in which the engaging portion 31 rotates from the start point S to the predetermined position P is a non-rotation section S1 of the rotating member 12, and the rotating member 12 does not rotate. Therefore, in the non-rotation section S1, no braking force is generated by the rotary damper 10. In this way, the rotary damper 10 according to the fourth embodiment has the non-rotation section S1 of the rotating member 12 while the engaging portion 31 rotates from the start point S to the end point E.

[0049] When the engaging portion 31 and the first engaged portion 13 engage with each other, the engaging portion 31 comes into contact with the first engaged portion 13, as shown in FIG. 16 . When the engaging portion 31 rotates toward the end point E in this state, the engaging portion 31 presses the first engaged portion 13, causing the rotating member 12 to rotate in one direction. This rotation causes the partition wall 19 to move around the shaft portion 15 while receiving resistance from the oil. Therefore, the rotary damper 10 generates a braking force when the rotating member 12 rotates in one direction. Furthermore, when the engaging portion 31 rotates toward the end point E while in contact with the first engaged portion 13, the spring 26 expands, storing elastic energy in the spring 26. As a result, the seat back reclines at a low speed and comes into contact with the seat cushion 33. FIG. 17 shows the state in which the engaging portion 31 is positioned at the end point E.

[0050] When the engaging portion 31 rotates from the end point E to the predetermined position P, the first engaged portion 13 moves following the rotation of the engaging portion 31 due to the restoring force (release of elastic energy) of the spring 26. If the hand used to raise the seat back is released from the seat back while the engaging portion 31 is present between the end point E and the predetermined position P, the engaging portion 31, which had been rotating toward the start point S, rotates toward the end point E, and the rotating member 12 rotates in one direction, generating a braking force. Therefore, with the rotary damper 10 according to the fourth embodiment, the seat back can be reclined at a low speed even if the hand is released from the seat back while the engaging portion 31 is present between the end point E and the predetermined position P.

[0051] The rotary damper 10 employed in the fourth embodiment generates a braking force even when the rotating member 12 rotates in the reverse direction when the engaging portion 31 rotates from the end point E to the predetermined position P. However, this braking force is neutralized or reduced by the restoring force of the spring 26, so the load when raising the seat back is reduced.

[0052] When engaging portion 31 rotates from predetermined position P to starting point S, spring 26 returns to its natural length at predetermined position P, and therefore engaging portion 31 moves away from first engaged portion 13, as shown in FIG. 18 . In this way, spring 26 has the function of stopping first engaged portion 13 from following engaging portion 31 at predetermined position P. As described above, when engaging portion 31 moves away from first engaged portion 13, rotation of rotating member 12 in the reverse direction is stopped, and therefore, when engaging portion 31 rotates from predetermined position P to starting point S, that is, in non-rotation section S1 of rotating member 12, no braking force is generated. [Example]

[0053] Referring to FIG. 19, rotary damper 10 according to the fifth embodiment differs from that of the fourth embodiment in that non-rotating member 11 has a body portion 27 connected to an axis that is the center of rotation of controlled object 30.

[0054] The body portion 27 has a circular cross section and an outer diameter slightly smaller than the inner diameter of the peripheral wall 18 that constitutes the rotating member 12. A gap 28 formed between the body portion 27 and the peripheral wall 18 is filled with a viscous material such as grease.

[0055] Similar to the fourth embodiment, the rotary damper 10 according to the fifth embodiment has a spring 26 that causes the first engaged portion 13 to follow the engaging portion 31 when the engaging portion 31 rotates from the end point E to a predetermined position P. When the engaging portion 31 rotates toward the end point E while the engaging portion 31 rotates from the end point E to the predetermined position P, a viscous shear stress of the viscous material is generated, and this acts as a braking force on the controlled object. Also, similar to the fourth embodiment, the rotary damper 10 according to the fifth embodiment has a spring 26 that stops the first engaged portion 13 from following the engaging portion 31 at the predetermined position P, and therefore does not generate a braking force (viscous shear stress of the viscous material) when the engaging portion 31 rotates from the predetermined position P to the start point S. [Explanation of symbols]

[0056] 10 Rotary Damper 11 Non-rotating member 12 Rotating member 13 First engaged part 14 Second engaged part 15 Shaft 16 vanes 17 Oil room 18 Peripheral wall 19 Bulkhead 20 grooves 21 Nails 22 Slope 23 Cap 24 groove 25 nails 26 Spring 27 Torso 28 Gap 30 Controlled Objects 31 Engagement part 32 axes 33 Seat cushion

Claims

1. a rotary damper comprising: a non-rotating member; a rotating member that rotates around the non-rotating member; a first engaged portion provided on the rotating member; and a second engaged portion provided on the rotating member with a gap between the first engaged portion and the second engaged portion; an engaging portion that is installed between the first engaged portion and the second engaged portion and rotates together with a controlled object presses the first engaged portion, causing the rotating member to rotate in one direction, and generating a braking force when the rotating member rotates in one direction; and a non-rotating section of the rotating member while the engaging portion rotates from a start point of a movable range of the engaging portion to an end point of the movable range of the engaging portion, A rotary damper characterized by having a first means for causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position, and a second means for stopping the first engaged portion from following at the predetermined position.

2. 2. The rotary damper according to claim 1, wherein the first means comprises a groove formed in the first engaged portion and a claw formed in the groove, the groove accommodating the engaging portion and the claw preventing the engaging portion accommodated in the groove from escaping.

3. 2. The rotary damper according to claim 1, further comprising a cap that covers the first engaged portion, wherein the first means comprises a groove formed in the cap and a pawl formed in the groove, the groove accommodating the engaging portion and the pawl preventing the engaging portion accommodated in the groove from escaping.

4. 2. The rotary damper according to claim 1, wherein the first means comprises a spring having a function of causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position.

5. 2. The rotary damper according to claim 1, wherein the second means comprises a vane provided on the non-rotating member and a partition wall provided on the rotating member, and the vane and the partition wall come into contact with each other at the predetermined position to prevent the rotating member from rotating in the reverse direction.

6. a rotary damper comprising: a non-rotating member; a rotating member that rotates around the non-rotating member; a first engaged portion provided on the rotating member; and a second engaged portion provided on the rotating member with a gap between the first engaged portion and the second engaged portion; an engaging portion that is installed between the first engaged portion and the second engaged portion and rotates together with a controlled object presses the first engaged portion, causing the rotating member to rotate in one direction, and generating a braking force when the rotating member rotates in one direction; and a non-rotating section of the rotating member while the engaging portion rotates from a start point of a movable range of the engaging portion to an end point of the movable range of the engaging portion, A rotary damper characterized by comprising a spring having a first function of causing the first engaged portion to follow the engaging portion when the engaging portion rotates from the end point to a predetermined position, and a second function of stopping the first engaged portion from following at the predetermined position.

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