Reclining device

Abstract

To provide a reclining device configured to enable a bush to bear force over the whole circumference, which enables the bush to receive even external force in any directions of 360° so as to stabilize sliding movements.SOLUTION: A reclining device 100 according to the present invention comprises: an external tooth gear 10; an inner tooth gear 20; a rotary shaft 30, which is concentrically and rotatably fitted into a cylindrical boss of the inner tooth gear 20, and rotates either one of the external tooth gear and the internal tooth gear about a gear shaft of the other; a bush 40, which is formed in a toric shape, with a center of an outer peripheral surface and a center of an inner peripheral surface being eccentric, has a cam housing part 44 at an inner periphery side thereof and rotates along with rotation of the rotary shaft; a pair of wedge-shaped cams 50; and a spring 60 that energizes the pair of wedge-shaped cams so that the cams simultaneously contact the bush and the cylindrical boss, where a gap between a through-hole of the external tooth gear and the bush is larger than a gap between the cylindrical boss of the internal tooth gear and the bush.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a reclining device. [Background technology]

[0002] The right holder has a seat reclining device that holds a seat back tiltably relative to a seat cushion, a first frame fixed to one of the seat cushion and the seat back, and a second frame fixed to the other of the seat cushion and the seat back; an externally toothed gear connected to the first frame, having external teeth formed on an outer circumferential surface and an externally toothed boss portion coaxial with the axial direction on an inner circumferential surface; an internal gear connected to the second frame, having an outer circumferential surface formed with internal teeth capable of meshing with the external teeth, and having an inner circumferential surface formed with a cylindrical boss portion coaxial with the axial direction; a rotation shaft that is coaxially and rotatably fitted to the external gear and that causes one of the external gear and the internal gear to revolve around a gear shaft of the other of the external gear and the internal gear, a pair of wedge-shaped cams that are interposed between the cylindrical boss portion and the external tooth boss portion, and that simultaneously contact the cylindrical boss portion side and the external tooth boss portion to regulate rotation between the cylindrical boss portion and the external tooth boss portion, and that slide at least one of the cylindrical boss portion side and the external tooth boss portion side to allow rotation between the cylindrical boss portion and the external tooth boss portion; a spring member for biasing the pair of wedge-shaped cams in a direction to simultaneously contact the cylindrical boss portion side and the external tooth boss portion side; a disk-shaped member that rotates with the rotation of the rotary shaft, the disk-shaped member extending in the axial direction and including a pair of cam pushing blades having tapered contact surfaces that push the pair of wedge-shaped cams in a direction away from at least one of the cylindrical boss portion side and the external tooth boss portion side; The patent document 1 proposes a leaf spring that presses the disk-shaped member against the pair of wedge-shaped cams and brings the tapered contact surface into contact with the pair of wedge-shaped cams, and the spring force is set to be weaker than that of the spring material.

[0003] According to this reclining device, the wedge-shaped cam is directly operated by the cam pushing blade of a disk-shaped member that is linked to the rotating shaft, which has the effect of making the rotational resistance between the external gear and the internal gear uniform, thereby making it possible to smoothly rotate the external gear and the internal gear.

[0004] In this reclining device, because only the wedge-shaped cam abuts against the bush, when a large force is applied to the seat back of the vehicle seat, the external force applied to the reclining device can only be received at the contact point between the bush and the wedge-shaped cam, which causes a problem that a large force is applied to a part depending on the direction of the applied external force, and for example, there are cases where the force must be received by the gear teeth, and when the force is received by the gear teeth in this way, there is a problem that the reclining device, which is a differential gear, may not be able to slide and rotate smoothly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-127210 A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the present invention has been made in consideration of these problems, and aims to provide a reclining device in which the bush can be supported around the entire circumference, stabilizing sliding by receiving external forces from any direction within 360° through the bush, and to provide a reclining device in which the time lag in movement of the gear mechanism can be reduced when a rotational force is applied to the drive shaft. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs the following means.

[0008] The reclining device of the present invention comprises: A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having external teeth formed on an outer peripheral surface and a through hole formed coaxially with the axial direction on an inner peripheral surface; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on an inner circumferential surface and that can mesh with the external teeth, and that has a cylindrical boss that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between an inner periphery of the through hole of the external gear and an outer periphery of the cylindrical boss of the internal gear, that is formed in an annular shape with an eccentric center of its outer periphery and a center of its inner periphery, that has a cam accommodating portion on its inner periphery side, and that has a protrusion or a fitting recess on a side surface of the thickest or thinnest portion in the eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the cylindrical boss of the internal gear and the bush to bring the bush into contact with the inner circumferential surface of the through hole of the external gear, thereby restricting the relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the cylindrical boss of the internal gear or the bush and the inner circumferential surface of the through hole of the external gear, thereby allowing the relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction to simultaneously contact the bush and the cylindrical boss, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A gap between the cylindrical boss of the internal gear and the bush is larger than a gap between the through hole of the external gear and the bush.

[0009] By adopting this configuration, the bush and the wedge-shaped cam can support the bearing over almost the entire circumference. Therefore, the bush can receive the external force from any direction of 360°, and the sliding can be stabilized. In addition, the bush has a protrusion on the side of the thickest or thinnest part in the eccentric direction, and the rotating shaft has a fitting recess that can support the protrusion without gaps from both sides in the rotation direction. This reduces the time lag until the gear mechanism starts operating when a rotational force is applied to the rotating shaft, which serves as the drive shaft.

[0010] Further, the reclining device according to the present invention is A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having external teeth formed on an outer peripheral surface and a through hole formed coaxially with the axial direction on an inner peripheral surface; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on an inner circumferential surface and that can mesh with the external teeth, and that has a cylindrical boss that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into a cylindrical boss of the internal gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between an inner periphery of the through hole of the external gear and an outer periphery of the cylindrical boss of the internal gear, that is formed in an annular shape with an eccentric center of an outer periphery surface and a center of an inner periphery surface, that has a cam accommodating portion on its outer periphery, and that has a protrusion or a fitting recess on a side surface of a thickest portion or a thinnest portion in an eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the cylindrical boss of the internal gear and the bush to bring the bush into contact with an inner peripheral surface of the through hole of the external gear, thereby restricting relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the through hole of the external gear or the bush and the cylindrical boss, thereby allowing relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction in which the pair of wedge-shaped cams simultaneously contact the bush and the through hole of the external gear, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A gap between the cylindrical boss of the internal gear and the bush is smaller than a gap between the through hole of the external gear and the bush.

[0011] By adopting such a configuration, the bush and the wedge-shaped cam can support the bearing over almost the entire circumference. Therefore, the bush can receive the external force from any direction of 360°, and the sliding can be stabilized. In addition, the bush has a protrusion on the side of the thickest or thinnest part in the eccentric direction, and the rotating shaft has a fitting recess that can support the protrusion without gaps from both sides in the rotation direction. This reduces the time lag until the gear mechanism starts operating when a rotational force is applied to the rotating shaft, which serves as the drive shaft.

[0012] Further, a reclining device according to the present invention is a seat reclining device that holds a seat back frame constituting a seat back so as to be tiltable relative to a seat cushion frame constituting a seat cushion, an external gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the external gear having external teeth formed on an outer circumferential surface and a cylindrical boss coaxial with an axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on its inner circumferential surface and that can mesh with the external teeth, and that has a through hole formed coaxially with the axial direction on its inner circumferential surface; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between the cylindrical boss of the external gear and the through hole of the internal gear, that is formed in an annular shape with an outer circumferential surface center and an inner circumferential surface center eccentric to each other, that has a cam accommodating portion on its inner circumferential side, and that has a protrusion or a fitting recess on a side surface of the thickest portion or the thinnest portion in the eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the cylindrical boss of the external gear and the bush to bring the bush into contact with the inner circumferential surface of the through hole of the internal gear, thereby restricting the relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the cylindrical boss of the external gear or the bush and the inner circumferential surface of the through hole of the internal gear, thereby allowing the relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction to simultaneously contact the bush and the cylindrical boss, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A gap between the through hole of the internal gear and the bush is smaller than a gap between the cylindrical boss of the external gear and the bush.

[0013] By adopting such a configuration, the bush can support the bearing over almost the entire circumference. Therefore, even if an external force is applied from any direction of 360°, the bush can receive the force and stabilize the sliding. Furthermore, when a large force is applied, the force received from the cylindrical boss of the internal gear and the through hole of the external gear is received by the bush, so that the application of a large force to the spring can be reduced. Therefore, instead of the wedge-shaped cam, the spring can be used as it is instead of the cam. Furthermore, the bush is provided with a protrusion on the side of the thickest or thinnest part in the eccentric direction, and the rotating shaft is provided with a fitting recess that can support the protrusion from both sides in the rotation direction without any gaps, so that the time lag until the gear mechanism starts operating can be reduced when a rotational force is applied to the rotating shaft that serves as the drive shaft.

[0014] Furthermore, the present invention provides a reclining device for a seat that holds a seat back frame constituting a seat back so as to be tiltable relative to a seat cushion frame constituting a seat cushion, the reclining device comprising: an external gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the external gear having external teeth formed on an outer circumferential surface and a cylindrical boss coaxial with an axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on its inner circumferential surface and that can mesh with the external teeth, and that has a through hole formed coaxially with the axial direction on its inner circumferential surface; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between the cylindrical boss of the external gear and the through hole of the internal gear, that is formed in an annular shape with an outer circumferential surface center and an inner circumferential surface center eccentric to each other, that has a cam accommodating portion on the outer circumferential side, and that has a protrusion or a fitting recess on a side surface of a thickest portion or a thinnest portion in an eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the through hole of the internal gear and the bush to bring the bush into contact with the outer circumferential surface of the cylindrical boss of the external gear, thereby restricting relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the through hole of the internal gear or the bush and the cylindrical boss of the external gear, thereby allowing relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction in which the pair of wedge-shaped cams simultaneously contact the bush and the through hole of the internal gear, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A gap between the through hole of the internal gear and the bush is larger than a gap between the cylindrical boss of the external gear and the bush.

[0015] By adopting this configuration, the bush can support the bearing over almost the entire circumference, as in the above-mentioned configuration. Therefore, the bush can receive the external force from any direction of 360°, thereby stabilizing the sliding. Furthermore, when a large force is applied, the force from the through hole of the internal gear and the cylindrical boss of the external gear is received by the bush, so that the application of a large force to the spring can be reduced. Therefore, instead of the wedge-shaped cam, the spring can be used as a cam. Furthermore, the bush is provided with a protrusion on the side of the thickest or thinnest part in the eccentric direction, and the rotating shaft is provided with a fitting recess that can support the protrusion from both sides in the rotation direction without any gaps, so that the time lag until the gear mechanism starts operating can be reduced when a rotational force is applied to the rotating shaft that serves as the drive shaft.

[0016] Furthermore, in the above-mentioned reclining device, there may be no wedge-shaped cam, and a spring accommodating portion may be formed on the inner or outer peripheral surface of the bush, and the ends of the springs may be arranged in the spring accommodating portion so as to urge them in directions away from each other.

[0017] In addition, in the reclining device according to the present invention, The amount of eccentricity between a center of the bush relative to the outer circumferential surface and a center of the inner circumferential surface may be equal to or greater than an amount of eccentricity between a center of the internal gear and a center of the external gear.

[0018] By setting this range, it is possible to reduce the occurrence of gaps between the external teeth of the external gear and the internal teeth of the internal gear. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a vehicle seat 200 to which a reclining device 100 according to the first embodiment is attached. [Diagram 2] FIG. 2 is a front view showing the internal structure of the reclining device 100 according to the first embodiment. [Diagram 3] FIG. 3 is an exploded perspective view showing the reclining device 100 according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. 2 according to the first embodiment. [Diagram 5] FIG. 5 is a schematic diagram illustrating the bush 40 according to the first embodiment. [Figure 6] FIG. 6 is a front view showing the internal structure of another embodiment of the reclining device 100 according to the first embodiment. [Figure 7] FIG. 7 is a front view showing the internal structure of another embodiment of the reclining device 100 according to the first embodiment. [Figure 8] FIG. 8 is a front view showing the internal structure of the reclining device 100 according to the second embodiment. [Figure 9] FIG. 9 is an exploded perspective view showing the reclining device 100 according to the third embodiment. [Figure 10] FIG. 10 is a front view showing the internal structure of another embodiment of the reclining device 100 according to the third embodiment. [Figure 11] FIG. 11 is a front view showing the internal structure of the reclining device 100 according to the fourth embodiment. [Figure 12] FIG. 12 is a front view showing the internal structure of the reclining device 100 according to the fifth embodiment. [Figure 13] FIG. 13 is a front view showing the internal structure of the reclining device 100 according to the sixth embodiment. [Figure 14] FIG. 14 is a front view showing the internal structure of a reclining device 100 according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a reclining device 100 according to an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram of a vehicle seat 200, Fig. 2 is a front view showing the internal structure of the reclining device 100, Fig. 3 is an exploded perspective view of the reclining device 100, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 2. Note that the embodiments and drawings described below are intended to exemplify a portion of the embodiments of the present invention, and are not intended to be used for the purpose of limiting the present invention to these configurations. Note that the same or similar reference symbols are used for corresponding components in each drawing.

[0021] 1, the reclining device 100 according to the present invention is a device attached to a seat cushion 210 of a vehicle seat 200 and a seat back 220 that is tiltably attached to the seat cushion 210 at a central position of the tilting movement, and provides a tilting function to the seat back 220. Specifically, the reclining device 100 is used by being attached between a seat cushion frame arranged inside the seat cushion 210 and a seat back frame arranged inside the seat back 220 directly or indirectly via another attachment plate 230 (hereinafter referred to as "attachment plate, etc.").

[0022] 2 or 3, the reclining device 100 according to the present invention mainly comprises an external gear 10, an internal gear 20, a rotating shaft 30, a bush 40, a pair of wedge-shaped cams 50a, 50b (50), a spring 60 as an elastic body, a spring cover 70, and a plate cover 80. Note that in Fig. 2, the spring cover 70 and the plate cover 80 are omitted in order to make the internal structure easier to see.

[0023] 3, the external gear 10 is formed in a disk shape, with external teeth 11 formed on the outer circumferential surface 10a and a cylindrical through hole 12 formed in the center. The external gear 10 is provided with a protrusion 13 on the outer surface 10b, and is attached by welding or the like in a state where it fits into a fitting hole provided in a mounting plate or the like 230.

[0024] The internal gear 20 is formed in a disk shape having a larger diameter than the external gear 10, and a cylindrical recess is formed so that the external gear 10 can be mounted inside, and the internal teeth 21 are formed on the inner peripheral surface 20a of the recess. The internal teeth 21 are formed at least one more than the number of teeth of the external teeth 11 of the external gear 10, and the external gear 10 and the internal gear 20 are engaged with the internal teeth 21 and the external teeth 11 so that the center C1 of the external gear 10 and the center C2 of the internal gear 20 are eccentric, as shown in FIG. 2. Therefore, the external gear 10 and the internal gear 20 form a differential gear, and when the internal gear 20 makes one revolution around the external teeth 11, the rotation proceeds by the difference between the teeth of the internal teeth 21 and the external teeth 11. That is, for example, if there is only one difference in tooth, when the external gear 10 makes one revolution around the internal gear 20, it rotates by one tooth. A cylindrical boss 22 is provided at the center of the internal gear 20. As shown in FIG. 3, the internal gear 20 is also provided with a protrusion 23 on its outer surface, which is fitted into a fitting hole provided in a mounting plate or the like 230 and attached by welding or the like.

[0025] The rotating shaft 30 is coaxially rotatably inserted into the cylindrical boss 22 of the internal gear 20. The rotating shaft 30 is rotated when adjusting the tilt of the seat back 220, and has serrations 31 on its inner cylindrical surface to receive the rotational force of a tilt motor. The rotating shaft 30 has a fitting recess 32 that fits with a protrusion 42 provided on a bush 40, which will be described later. The fitting recess 32 is attached so as to sandwich the protrusion 42 from both sides, so that the bush 40 rotates in the same manner as the rotating shaft 30 whether the rotating shaft 30 is rotated clockwise or counterclockwise.

[0026] The bush 40 is an annular or ring-shaped member disposed between the outer peripheral surface 22a of the cylindrical boss 22 of the internal gear 20 and the through hole 12 of the external gear 10. As shown in FIG. 5, the bush 40 is formed in a ring shape in which the center C3 of the inner peripheral surface 41a of the cylindrical boss hole 41 is offset from the center C4 of the outer peripheral surface 43. As shown in FIG. 2, the cylindrical boss hole 41 of the bush 40 has a diameter slightly larger than the diameter of the outer peripheral surface 22a of the cylindrical boss 22, and a gap A is formed between the cylindrical boss hole 41 and the outer peripheral surface 22a of the cylindrical boss 22. The gap A is preferably set to about 0.06 mm to 0.12 mm. The outer peripheral surface 43 of the bush 40 is disposed in the through hole 12 of the external gear 10 and is formed to have a diameter slightly smaller than the diameter of the through hole 12 of the external gear 10, and a gap B is formed between the outer peripheral surface 43 of the bush 40 and the through hole 12 of the external gear 10. It is advisable to set gap B to approximately 0.02 mm to 0.06 mm. At this time, in order to mesh the external gear 10 and the internal gear 20, the relationship between gap A and gap B needs to be Gap A > Gap B. In other words, the gap A between the cylindrical boss 22 of the internal gear 20 and the bush 40 is set to be larger than the gap B between the through hole 12 of the external gear 10 and the bush 40.

[0027] The bush 40 has a protrusion 42 on its side that fits into the fitting recess 32. This allows the bush 40 to rotate in synchronization with the rotation of the rotating shaft 30. As shown in FIG. 2, the protrusion 42 is provided at the thickest part (part α) in the eccentric direction (direction of arrow D) where the center C3 of the bush 40 with respect to the outer circumferential surface 43 and the center C4 of the cylindrical boss hole 41 are offset. By providing the protrusion 42 at this eccentric position, the bush 40 reciprocates in the eccentric direction (direction of arrow D) when it rotates, but it can slide in the eccentric direction within the fitting recess 32, and can be fitted without a gap in the rotation direction of the protrusion 42. Therefore, when the rotating shaft 30 is rotated by a motor or the like, the gear mechanism can be operated immediately without a time lag. On the other hand, if the protrusion 42 is not provided at this eccentric position, it is necessary to provide a play (gap) to cushion the movement of the bush 40 when it moves in the eccentric direction, as shown in FIG. 14. Therefore, when the rotating shaft 30 is moved, a time lag occurs due to this play before the bushing starts to operate. In this manner, in this embodiment, by providing the protrusion 42 at a position in the eccentric direction, the protrusion 42 that fits into the fitting recess 32 can be installed without leaving a gap in the rotational direction, so that the time lag can be reduced.

[0028] Between the inner peripheral surface of the cylindrical boss hole 41 of the bush 40 and the outer peripheral surface 22a of the cylindrical boss 22 of the internal gear 20, a pair of wedge-shaped cams 50a and 50b (50) are provided so as to contact both. As shown in FIG. 3, the wedge-shaped cams 50a and 50b are formed symmetrically with respect to a plane, and the concave surface 51 (inner surface) of the wedge-shaped cam 50 has the same curved surface as the curved surface of the outer peripheral surface 22a of the cylindrical boss 22, and the convex surface 52 (outer surface) is formed so that the thickness gradually becomes thinner from the opposite side toward the direction away from each other. In the bush 40, two cam accommodating portions 44 are formed so that the gap gradually narrows from the opposite side according to the shape of the wedge-shaped cam 50, and the wedge-shaped cam 50 is inserted into the cam accommodating portions 44. The cam accommodating portions 44 are provided on both sides in the rotation direction, sandwiching the thickest portion α of the bush 40. The thickest portion has an extension 46 that extends toward the outer circumferential surface 22 a of the cylindrical boss 22 .

[0029] 3, the spring 60 has an annular portion 61 and end portions 62a, 62b that rise up so as to be bent at 90° from the annular portion 61, and the end portions 62a, 62b are disposed on the end faces of the thick-walled portions of the wedge-shaped cams 50a and 50b, and are biased in directions in which the wedge-shaped cams 50a and 50b move away from each other. This allows the external gear 10 to be pressed against the internal gear 20 to mesh with it. The spring 60 may be made of another elastic material, such as rubber, as long as it is capable of biasing the wedge-shaped cams 50a and 50b.

[0030] As shown in FIG. 4, the spring cover 70 is a cover for holding the spring 60 so that it does not come off, and is not particularly limited as long as it has a shape capable of holding the spring 60.

[0031] The plate cover 80 is formed from a metal plate formed in a circular ring shape and is fixed to the outer end of the internal gear 20 by welding or the like, and has the function of restricting axial movement of the external gear 10.

[0032] The reclining device 100 thus manufactured operates as follows: When no force is applied to the rotating shaft 30 and it is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in the direction separating them, and are in contact with the bush 40 and the outer circumferential surface 22a of the cylindrical boss 22 of the internal gear 20. As a result, the relative movement between the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0033] From this locked state, when the rotating shaft 30 is rotated counterclockwise, for example, in FIG. 2, the bush 40 engaged with the rotating shaft 30 also rotates. A wedge angle is set on the inner wall of the cam accommodating portion 44 of the bush 40, and the wedge angle inner wall is in contact with the wedge-shaped cam 50. When the bush 40 rotates, a gap is generated between the wedge angle inner wall and the wedge-shaped cam 50, and the wedge is removed. The rotating shaft 30 and the bush 40 rotate counterclockwise relative to the internal gear 20, and as a result, a gap is generated between the bush 40 and the cylindrical boss 22 and between the bush 40 and the through hole 12 of the external gear 10, and the external gear 10 becomes rotatable relative to the internal gear 20. Accordingly, the wedge-shaped cam 50a rotates counterclockwise by the biasing force of the spring 60 so as to fill the gap. The wedge-shaped cam 50 rotates counterclockwise so as to slide together with the rotating shaft 30 and the bush 40. In this way, the external gear 10, the internal gear 20 and the rotating shaft 30 constitute a differential gear mechanism. Note that clockwise rotation can also be achieved in the same manner.

[0034] In the reclining device 100 manufactured in this manner, the bush 40 is formed in a ring shape, so when an external force is applied to the internal gear 20 or the external gear 10, the internal gear 20 or the external gear 10 will attempt to move in the direction of the external force or the reaction force. However, in the direction of the attempted movement, the bush is sandwiched perpendicularly between the outer surface 22a of the cylindrical boss 22 of the internal gear 20 and the through hole 12 of the external gear 10, and can act as a bearing by minimizing the component force components, thereby stabilizing sliding and ensuring smooth rotation.

[0035] In addition, when the rotating shaft 30 is rotated, the protrusion 42 of the bush 40 is engaged with the engaging recess 32 which has no gap in the rotational direction, so that the gear mechanism can be operated immediately without any time lag.

[0036] In the first embodiment, the protrusion 42 of the bushing 40 is provided at the thickest part in the eccentric direction (direction of arrow D) where the center C3 of the bushing 40 with respect to the outer circumferential surface 43 and the center C4 of the cylindrical boss hole 41 are offset, but as shown in Fig. 6, it may be provided at the thinnest part in the eccentric direction (direction of arrow D). Even when provided at such a position in the eccentric direction, the bushing 40 can slide in the eccentric direction within the fitting recess 32 even if it reciprocates in the eccentric direction (direction of α) when rotating, so that the protrusion 42 can be fitted without a gap in the rotation direction. Therefore, when the rotating shaft 30 is rotated by a motor or the like, the gear mechanism can be operated immediately without a time lag.

[0037] Furthermore, in the first embodiment described above, a protrusion 42 is provided on the bushing 40, and a mating recess 32 is provided on the rotating shaft 30. However, as shown in FIG. 7, a mating recess 32 may be provided on the bushing 40, and a protrusion 42 may be provided on the rotating shaft 30.

[0038] Second embodiment The reclining device 100 according to the second embodiment is shown in Fig. 8. The reclining device 100 according to the second embodiment is similar to the first embodiment except for the bush 40, so the description thereof will be omitted.

[0039] In the bush 40 according to the second embodiment, a cam accommodating portion 44 is formed between the outer circumferential surface 43 of the bush 40 and the through hole 12 of the external gear 10 such that the gap gradually narrows from the opposing side, and the wedge-shaped cams 50a, 50b are fitted into this cam accommodating portion 44. That is, the first embodiment differs in that the cam accommodating portion 44 is formed on the inner circumferential side of the bush 40, whereas the second embodiment differs in that the cam accommodating portion 44 is formed on the outer circumferential side of the bush 40. In the locked state, a gap A is formed between the inner periphery of the cylindrical boss hole 41 and the outer circumferential surface 22a of the cylindrical boss 22, and a gap B is formed between the through hole 12 of the external gear 10 and the bush 40. In the second embodiment, the relationship between the gap A between the inner periphery of the cylindrical boss hole 41 and the outer circumferential surface 22a of the cylindrical boss 22 and the gap B between the through hole 12 of the external gear 10 and the bush 40 must be gap A<gap B. That is, the gap A between the cylindrical boss 22 of the internal gear 20 and the inner periphery of the cylindrical boss hole 41 is set to be smaller than the gap B between the through hole 12 of the external gear 10 and the bush 40 .

[0040] As in the first embodiment, the protrusion 42 is provided at the thickest or thinnest part in the eccentric direction (direction of arrow D) where the center C3 with respect to the outer circumferential surface 43 of the bushing 40 and the center C4 of the cylindrical boss hole 41 are offset. By providing the protrusion 42 at this eccentric position, the bushing 40 can slide in the eccentric direction within the fitting recess 32 even if it reciprocates in the eccentric direction (direction of α) when it rotates, so that the protrusion 42 can be fitted in without any gap in the rotation direction.

[0041] In the reclining device 100 according to the second embodiment, when no force is applied to the rotating shaft 30 and the rotating shaft 30 is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in directions separating them, and are in contact with the bush 40 and the inner circumferential surface of the through hole 12 of the external gear 10. For this reason, the relative movement of the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0042] When the rotating shaft 30 is rotated counterclockwise from this locked state, the bush 40 engaged with the rotating shaft 30 also rotates. In addition, a wedge angle is set on the inner wall of the cam accommodating portion 44 of the bush 40, and the wedge angle inner wall is in contact with the wedge-shaped cam. This rotation creates a gap between the wedge angle inner wall and the wedge-shaped cam 50, and the wedge is removed. The rotating shaft 30 and the bush 40 rotate counterclockwise relative to the internal gear 20, and as a result, a gap is created between the bush 40 and the cylindrical boss 22 and between the bush 40 and the through hole 12 of the external gear 10, and the external gear 10 becomes rotatable relative to the internal gear 20. Accordingly, the wedge-shaped cam 50a rotates counterclockwise by the biasing force of the spring 60 so as to fill the gap. The wedge-shaped cam 50 rotates counterclockwise so as to slide together with the rotating shaft 30 and the bush 40. In this way, the external gear 10, the internal gear 20 and the rotating shaft 30 constitute a differential gear mechanism. Note that clockwise rotation can also be achieved in the same manner.

[0043] In the reclining device 100 manufactured in this manner, the bush 40 is formed in a ring shape, so when an external force is applied to the internal gear 20 or the external gear 10, the internal gear 20 or the external gear 10 will attempt to move in the direction of the external force or the reaction force. However, in the direction of the attempted movement, the bush 40 is sandwiched perpendicularly between the outer surface 22a of the cylindrical boss 22 of the internal gear 20 and the inner surface of the through hole 12 of the external gear 10, and can act as a bearing by minimizing the component force components, thereby stabilizing sliding and ensuring smooth rotation.

[0044] In the reclining device of this second embodiment, when the rotating shaft 30 is rotated, the protrusion 42 of the bushing 40 engages with the mating recess 32 which has no gap in the rotational direction, so that the gear mechanism can be operated immediately without any time lag.

[0045] In the second embodiment, the protrusion 42 of the bush 40 may be provided at the portion having the thinnest thickness in the eccentric direction. Also, the bush 40 may be provided with the fitting recess 32, and the rotating shaft 30 may be provided with the protrusion 42.

[0046] Third embodiment A reclining device 100 according to the third embodiment is shown in Fig. 9 or 10. The reclining device 100 according to the third embodiment differs from the reclining device 100 according to the first embodiment in that a cylindrical boss 14 is provided at the center of the external gear 10, and a through hole 25 is provided at the center of the internal gear 20. Also, a restricting cover 70 for preventing the rotating shaft 30, the bush 40, the wedge-shaped cam 50, and the spring 60 from moving in the axial direction is provided on the outer surface side of the internal gear 20, and this restricting cover 70 is provided with a protrusion 71 that fits into a fitting hole of a mounting plate or the like 230. Meanwhile, the plate cover 80 is formed of a metal plate formed in an annular shape, is disposed on the outer surface side of the external gear 10, and is fixed to the end of the outer periphery of the internal gear 20 by welding or the like, thereby restricting the axial movement of the external gear 10.

[0047] The rotating shaft 30, the bush 40, and the spring 60 are manufactured symmetrically to those of the first embodiment. The bush 40 is disposed between the outer peripheral surface 14a of the cylindrical boss 14 of the external gear 10 and the through hole 25 of the internal gear 20 so that the cylindrical boss 14 is inserted into the cylindrical boss hole 41 of the bush 40. The rotating shaft 30 is disposed in the cylindrical boss 14 so as to rotate coaxially with the central axis of the cylindrical boss 14, and similarly to the first embodiment, the protrusions 42 provided on the bush 40 are attached so as to be sandwiched from both sides by the fitting recesses 32, so that the bush 40 rotates in the same manner as the rotating shaft 30 whether the rotating shaft 30 is rotated clockwise or counterclockwise. A pair of wedge-shaped cams 50a and 50b (50) are provided between the inner peripheral surface of the cylindrical boss hole 41 of the bush 40 and the outer peripheral surface 14a of the cylindrical boss 14 of the external gear 10 so as to contact both of them. Two cam housings 44 are formed on the inner peripheral surface of the bush 40 in accordance with the shape of the wedge-shaped cam 50 so that the gap between them gradually narrows from the opposing side, and the wedge-shaped cam 50 is inserted into the cam housings 44. The spring 60 has an annular portion 61 and ends 62a and 62b that rise up from the annular portion 61 so as to be bent at 90 degrees. The ends 62a and 62b are disposed on the end faces of the thick-walled portions of the wedge-shaped cams 50a and 50b, and are biased in directions in which the wedge-shaped cams 50a and 50b move away from each other. This allows the external gear 10 to be pressed against the internal gear 20 and engaged with it.

[0048] As in the first embodiment, the protrusion 42 is provided at the thickest or thinnest part in the eccentric direction (direction of arrow D) where the center C3 with respect to the outer circumferential surface 43 of the bushing 40 and the center C4 of the cylindrical boss hole 41 are offset. By providing the protrusion 42 at this eccentric position, the bushing 40 can slide in the eccentric direction within the fitting recess 32 even if it reciprocates in the eccentric direction (direction of α) when it rotates, so that the protrusion 42 can be fitted in without any gap in the rotation direction.

[0049] The cylindrical boss hole 41 of the bushing 40 has a diameter slightly larger than the diameter of the outer peripheral surface 14a of the cylindrical boss 14, and in the locked state, a gap A' is formed between the cylindrical boss hole 41 and the outer peripheral surface 14a of the cylindrical boss 14. The gap A' between the cylindrical boss hole 41 of the bushing 40 and the outer peripheral surface 14a of the cylindrical boss 14 is preferably set to approximately 0.06 mm to 0.12 mm. The outer peripheral surface 43 of the bushing 40 is disposed in the through hole 25 of the internal gear 20 and is formed to have a diameter slightly smaller than the diameter of the through hole 25 of the internal gear 20, and in the locked state, a gap B' is formed between the outer peripheral surface 43 of the bushing 40 and the through hole 25 of the internal gear 20. The gap B' between the outer peripheral surface 43 of the bushing 40 and the through hole 25 of the internal gear 20 is preferably set to approximately 0.02 mm to 0.06 mm. At this time, in order to mesh the external gear 10 and the internal gear 20, the relationship between gap A' and gap B' needs to be Gap A' > Gap B'. In other words, the gap B' between the through hole 25 of the internal gear 20 and the bush 40 is set to be smaller than the gap A' between the cylindrical boss 14 of the external gear 10 and the bush 40.

[0050] The reclining device 100 thus manufactured operates as follows: When no force is applied to the rotating shaft 30 and it is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in the direction separating them, and are in contact with the bush 40 and the outer circumferential surface 14a of the cylindrical boss 14 of the external gear 10. As a result, the relative movement of the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0051] When the rotating shaft 30 is rotated counterclockwise from this locked state, the bush 40 engaged with the rotating shaft 30 also rotates. A wedge angle is set on the inner wall of the cam accommodating portion 44 of the bush 40, and the wedge angle inner wall is in contact with the wedge-shaped cam 50. This rotation creates a gap between the wedge angle inner wall and the wedge-shaped cam 50, and the wedge is removed. The rotating shaft 30 and the bush 40 rotate counterclockwise relative to the internal gear 20, and as a result, a gap is created between the bush 40 and the cylindrical boss 14 and between the bush 40 and the through hole 25 of the internal gear 20, and the external gear 10 becomes rotatable relative to the internal gear 20. Accordingly, the wedge-shaped cam 50a rotates counterclockwise by the biasing force of the spring 60 so as to fill the gap. The wedge-shaped cam 50 rotates counterclockwise so as to slide together with the rotating shaft 30 and the bush 40. In this way, the external gear 10, the internal gear 20 and the rotating shaft 30 constitute a differential gear mechanism. Note that clockwise rotation can also be achieved in the same manner.

[0052] In the reclining device 100 manufactured in this manner, the bush 40 is formed in a ring shape, so when an external force is applied to the internal gear 20 or the external gear 10, the internal gear 20 or the external gear 10 will attempt to move in the direction of the external force or the reaction force. However, in the direction of the attempted movement, the bush 40 is sandwiched perpendicularly between the outer surface 14a of the cylindrical boss 14 of the external gear 10 and the through hole 25 of the internal gear 20, and can act as a bearing by minimizing the component force components, thereby stabilizing sliding and ensuring smooth rotation.

[0053] In the reclining device of the third embodiment, when the rotating shaft 30 is rotated, the protrusion 42 of the bushing 40 engages with the mating recess 32 which has no gap in the rotational direction, so that the gear mechanism can be operated immediately without any time lag.

[0054] In the third embodiment, the protrusion 42 of the bush 40 may be provided at the portion having the thinnest thickness in the eccentric direction. Also, the bush 40 may be provided with the fitting recess 32, and the rotating shaft 30 may be provided with the protrusion 42.

[0055] (Fourth embodiment) A reclining device 100 according to the fourth embodiment is shown in Fig. 11. The reclining device 100 according to the fourth embodiment is similar to the third embodiment except for the bushing 40, so a description thereof will be omitted.

[0056] In the bush 40 according to the fourth embodiment, a cam accommodating portion 44 is formed between an outer peripheral surface 43 of the bush 40 and a through hole 25 of the internal gear 20 such that the gap gradually narrows from the opposing side, and a wedge-shaped cam 50 is fitted into this cam accommodating portion 44. That is, the third embodiment differs in that the cam accommodating portion 44 is formed on the inner peripheral side of the bush 40, whereas the fourth embodiment differs in that the cam accommodating portion 44 is formed on the outer peripheral side of the bush 40. In the locked state, a gap A' is formed between the cylindrical boss 14 of the external gear 10 and the inner peripheral surface of the bush 40, and a gap B' is formed between the through hole 25 of the internal gear 20 and the bush 40. The relationship between the gap A' between the cylindrical boss 14 of the external gear 10 and the inner peripheral surface of the bush 40 and the gap B' between the through hole 25 of the internal gear 20 and the bush 40 needs to be gap A'<gap B'. That is, the gap B' between the through hole 25 of the internal gear 20 and the bush 40 is set to be larger than the gap A' between the cylindrical boss 14 of the external gear 10 and the inner periphery of the cylindrical boss hole 41 of the bush 40 .

[0057] As in the first embodiment, the protrusion 42 is provided at the thickest or thinnest part in the eccentric direction (direction of arrow D) where the center C3 with respect to the outer circumferential surface 43 of the bushing 40 and the center C4 of the cylindrical boss hole 41 are offset. By providing the protrusion 42 at this eccentric position, the bushing 40 can slide in the eccentric direction within the fitting recess 32 even if it reciprocates in the eccentric direction (direction of α) when it rotates, so that the protrusion 42 can be fitted in without any gap in the rotation direction.

[0058] In the reclining device 100 according to the fourth embodiment, when no force is applied to the rotating shaft 30 and the rotating shaft 30 is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in directions separating them, and are in contact with the bush 40 and the inner circumferential surface of the through hole 25 of the internal gear 20. For this reason, the relative movement between the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0059] When the rotating shaft 30 is rotated counterclockwise from this locked state, the bush 40 engaged with the rotating shaft 30 also rotates. A wedge angle is set on the inner wall of the cam accommodating portion 44 of the bush 40, and the wedge angle inner wall is in contact with the wedge-shaped cam. This rotation creates a gap between the wedge angle inner wall and the wedge-shaped cam 50, and the wedge is removed. The rotating shaft 30 and the bush 40 rotate counterclockwise relative to the internal gear 20, and as a result, a gap is created between the bush 40 and the cylindrical boss 14 and between the bush 40 and the through hole 25 of the internal gear 20, and the external gear 10 becomes rotatable relative to the internal gear 20. Accordingly, the wedge-shaped cam 50a rotates counterclockwise by the biasing force of the spring 60 so as to fill the gap. The wedge-shaped cam 50 rotates counterclockwise so as to slide together with the rotating shaft 30 and the bush 40. In this way, the external gear 10, the internal gear 20 and the rotating shaft 30 constitute a differential gear mechanism. Note that clockwise rotation can also be achieved in the same manner.

[0060] In the reclining device 100 manufactured in this manner, the bush 40 is formed in a ring shape, so when an external force is applied to the internal gear 20 or the external gear 10, the internal gear 20 or the external gear 10 will attempt to move in the direction of the external force or the reaction force. However, in the direction of the attempted movement, the bush 40 is sandwiched perpendicularly between the outer surface 14a of the cylindrical boss 14 of the external gear 10 and the inner surface of the through hole 25 of the internal gear 20, and can act as a bearing by minimizing the component force components, thereby stabilizing sliding and ensuring smooth rotation.

[0061] In the reclining device of the fourth embodiment, when the rotating shaft 30 is rotated, the protrusion 42 of the bushing 40 engages with the mating recess 32 which has no gap in the rotational direction, so that the gear mechanism can be operated immediately without any time lag.

[0062] In the fourth embodiment, the protrusion 42 of the bush 40 may be provided at the portion having the thinnest thickness in the eccentric direction. Also, the bush 40 may be provided with the fitting recess 32, and the rotating shaft 30 may be provided with the protrusion 42.

[0063] Fifth embodiment A reclining device 100 according to a fifth embodiment is shown in Figure 12. The reclining device 100 according to the fifth embodiment is substantially similar to the first embodiment except that there is no wedge-shaped cam 50, a spring accommodating portion 44 is formed on the inner peripheral surface of the bush 40, and ends 62a, 62b are arranged in the spring accommodating portion 44 so as to urge them in directions away from each other. Therefore, a description of parts other than the bush 40 and the spring 60 will be omitted.

[0064] Between the inner peripheral surface of the cylindrical boss hole 41 of the bushing 40 and the outer peripheral surface 22a of the cylindrical boss 22 of the internal gear 20, spring accommodating portions 44 are provided on both sides of the annular thickest portion α (the thickest part) of the bushing 40. The spring accommodating portions 44 are formed symmetrically with respect to a plane, and are formed so as to gradually become narrower from the opposing side. The thickest portion α has an extension portion 46 that extends toward the outer peripheral surface 22a of the cylindrical boss 22.

[0065] As in the first embodiment, the spring 60 has an annular portion 61 and end portions 62a, 62b that rise up so as to be bent at 90° from the annular portion 61. The end portions 62a, 62b are disposed in the spring accommodating portion 44, and the end portions 62a, 62b are biased in directions away from each other. As a result, the spring 60 itself presses the external gear 10 against the internal gear 20 to mesh with it.

[0066] The bushing 40 has a protrusion 42 on its side surface that fits into the fitting recess 32 described above. The protrusion 42 is provided at the thickest or thinnest part in the eccentric direction where the center of the bushing 40 with respect to the outer circumferential surface 43 and the center of the cylindrical boss hole 41 are offset, as in the first embodiment. By providing the protrusion 42 at this eccentric position, the bushing 40 can slide in the eccentric direction within the fitting recess 32 even if it reciprocates in the eccentric direction (direction α) when rotating, so that the protrusion 42 can be fitted in without any gap in the rotation direction.

[0067] The reclining device 100 thus manufactured operates as follows: When no force is applied to the rotating shaft 30 and it is not rotating, the spring 60 biases the bushing 40, and the bushing 40 contacts the outer circumferential surface 22a of the cylindrical boss 22 of the internal gear 20. As a result, the relative movement between the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0068] When the rotating shaft 30 is rotated counterclockwise from this locked state, the bush 40 engaged with the rotating shaft 30 also rotates. A wedge angle is set on the inner wall of the spring accommodating portion 44 of the bush 40, and the wedge angle inner wall is in contact with the ends 62a, 62b of the spring 60. When the bush 40 rotates, a gap is generated between the wedge angle inner wall and the ends 62a, 62b of the spring 60, and the ends 62a, 62b of the spring 60 are disengaged. This rotation applies a force in a direction to pull the end 62a of the spring 60 out of the gap by the side wall of the spring accommodating portion 44 of the bush 40, and the rotating shaft 30 and the bush 40 rotate counterclockwise relative to the internal gear 20. As a result, gaps are generated between the bush 40 and the cylindrical boss 22 and between the bush 40 and the through hole 12 of the external gear 10, and the external gear 10 becomes rotatable relative to the internal gear 20. Accordingly, the spring 60 rotates counterclockwise by the biasing force of the end 62b of the spring 60 so as to fill the gap. In this way, the spring 60 rotates counterclockwise so as to slide together with the rotating shaft 30 and the bush 40. In this way, the external gear 10, the internal gear 20 and the rotating shaft 30 constitute a differential gear mechanism. Note that clockwise rotation can also be achieved in the same manner.

[0069] In the reclining device 100 manufactured in this manner, the bush 40 is formed in a ring shape, so when an external force is applied to the internal gear 20 or the external gear 10, the internal gear 20 or the external gear 10 will attempt to move in the direction of the external force or the reaction force. However, in the direction of the attempted movement, the bush is sandwiched perpendicularly between the outer surface 22a of the cylindrical boss 22 of the internal gear 20 and the through hole 12 of the external gear 10, and can act as a bearing by minimizing the component force components, thereby stabilizing sliding and ensuring smooth rotation.

[0070] In the reclining device of the fifth embodiment, when the rotating shaft 30 is rotated, the protrusion 42 of the bushing 40 engages with the mating recess 32 which has no gap in the rotational direction, so that the gear mechanism can be operated immediately without any time lag.

[0071] In the fifth embodiment, the protrusion 42 of the bush 40 may be provided at the portion having the thinnest thickness in the eccentric direction. Also, the bush 40 may be provided with the fitting recess 32, and the rotating shaft 30 may be provided with the protrusion 42.

[0072] Sixth embodiment A reclining device 100 according to a sixth embodiment is shown in Fig. 13. In the sixth embodiment, as shown in Fig. 13, two spring accommodating portions 44 are formed on the outer circumferential surface 43 of the bush 40 such that the gap between them gradually narrows from the opposing side, and the ends 62a, 62b of the spring 60 are inserted into the spring accommodating portions 44. That is, in the above-mentioned embodiment, the spring accommodating portion 44 is formed on the inner circumferential side of the bush 40, whereas in the embodiment shown in Fig. 13, the spring accommodating portion 44 is formed on the outer circumferential side of the bush 40. This is an embodiment in which, unlike the second embodiment, there is substantially no wedge-shaped cam 50, the bush 40 is formed with the spring accommodating portion 44, and the ends 62a, 62b are disposed in the spring accommodating portions 44 so as to urge them in directions away from each other.

[0073] Similarly, compared to the third and fourth embodiments, there is no wedge-shaped cam 50, and two spring accommodating portions 44 are formed on the inner or outer circumferential surface 43 of the bush 40 so that the gap between them gradually narrows from the opposing side, and the ends 62a, 62b of the spring 60 may be inserted into these spring accommodating portions 44. The other configurations are the same as those of the third or fourth embodiment.

[0074] In the first to sixth embodiments described above, the bushing 40 may be formed in an annular or ring shape in which the amount of eccentricity γ between the center C3 relative to the outer circumferential surface 43 of the bushing 40 and the center C4 of the cylindrical boss hole 41 is larger than the amount of eccentricity β between the center C1 of the internal gear 20 and the center C2 of the external gear 10. In other words, the bushing 40 may be formed so that the amount of eccentricity γ is greater than the amount of eccentricity β.

[0075] Each component of the reclining device 100 varies depending on the manufacturing process, and a gap A is formed between the cylindrical boss hole 41 and the outer peripheral surface 22a of the cylindrical boss 22, and a gap B is formed between the external gear 10 and the through hole 12, so that a gap is generated between the external teeth 11 of the external gear 10 and the internal teeth 21 of the internal gear 20 due to the misalignment of the gaps. Therefore, by making the amount of eccentricity between the center C3 and the center C4 of the cylindrical boss hole 41 relative to the outer peripheral surface 43 of the bushing 40 greater than or equal to the amount of eccentricity between the center C1 of the internal gear 20 and the center C2 of the external gear 10, it is possible to reduce the generation of a gap between the external gear 10, the external teeth 11, and the internal teeth 21 of the internal gear 20.

[0076] It should be noted that the present invention is not limited to the above-described embodiment, and can be embodied in various forms within the technical scope of the present invention. [Industrial Applicability]

[0077] As shown in the above-described embodiment, the present invention is industrially applicable mainly as a reclining device for a vehicle seat. [Explanation of symbols]

[0078] 10...external gear, 10a...outer surface, 10b...outer surface, 11...external teeth, 12...through hole, 13...projection, 20...internal gear, 20a...inner surface, 21...internal teeth, 22...cylindrical boss, 22a...outer surface, 23...projection, 30...rotating shaft, 31...serration, 32...fitting recess, 40...bush, 41...hole for cylindrical boss, 42...projection, 43...outer surface, 44...cam accommodating portion, 50, 50a, 50b...wedge-shaped cam, 60...spring, 61...annular portion, 62a, 62b...end, 70...spring cover, 80...plate cover, 100...recliner, 200...vehicle seat, 210...seat cushion, 220...seat back, 230...mounting plate

Claims

1. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having an outer peripheral surface on which external teeth are formed and an inner peripheral surface on which a through hole is formed coaxially with the axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on an inner circumferential surface and that can mesh with the external teeth, and that has a cylindrical boss that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between an inner periphery of the through hole of the external gear and an outer periphery of the cylindrical boss of the internal gear, that is formed in an annular shape with an eccentric center of its outer periphery and a center of its inner periphery, that has a cam accommodating portion on its inner periphery side, and that has a protrusion or a fitting recess on a side surface of the thickest or thinnest portion in the eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the cylindrical boss of the internal gear and the bush to bring the bush into contact with the inner circumferential surface of the through hole of the external gear, thereby restricting the relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the cylindrical boss of the internal gear or the bush and the inner circumferential surface of the through hole of the external gear, thereby allowing the relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction to simultaneously contact the bush and the cylindrical boss, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the cylindrical boss of the internal gear and the bush is larger than a gap between the through hole of the external gear and the bush.

2. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having an outer peripheral surface on which external teeth are formed and an inner peripheral surface on which a through hole is formed coaxially with the axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on an inner circumferential surface and that can mesh with the external teeth, and that has a cylindrical boss that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into a cylindrical boss of the internal gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between an inner periphery of the through hole of the external gear and an outer periphery of the cylindrical boss of the internal gear, that is formed in an annular shape with an eccentric center of an outer periphery surface and a center of an inner periphery surface, that has a cam accommodating portion on its outer periphery, and that has a protrusion or a fitting recess on a side surface of a thickest portion or a thinnest portion in an eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the cylindrical boss of the internal gear and the bush to bring the bush into contact with an inner peripheral surface of the through hole of the external gear, thereby restricting relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the through hole of the external gear or the bush and the cylindrical boss, thereby allowing relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction to simultaneously contact the bush and the through hole of the external gear, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the cylindrical boss of the internal gear and the bush is smaller than a gap between the through hole of the external gear and the bush.

3. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an external gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the external gear having external teeth formed on an outer circumferential surface and a cylindrical boss coaxial with an axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth on an inner circumferential surface that are at least one more than the external teeth and that can mesh with the external teeth, and that has a through hole formed on the inner circumferential surface that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between the cylindrical boss of the external gear and the through hole of the internal gear, that is formed in an annular shape with an outer circumferential surface center and an inner circumferential surface center eccentric to each other, that has a cam accommodating portion on its inner circumferential side, and that has a protrusion or a fitting recess on a side surface of the thickest portion or the thinnest portion in the eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the cylindrical boss of the external gear and the bush to bring the bush into contact with the inner circumferential surface of the through hole of the internal gear, thereby restricting the relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the cylindrical boss of the external gear or the bush and the inner circumferential surface of the through hole of the internal gear, thereby allowing the relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction to simultaneously contact the bush and the cylindrical boss, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the through hole of the internal gear and the bush is smaller than a gap between the cylindrical boss of the external gear and the bush.

4. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an external gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the external gear having external teeth formed on an outer circumferential surface and a cylindrical boss coaxial with an axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth on an inner circumferential surface that are at least one more than the external teeth and that can mesh with the external teeth, and that has a through hole formed on the inner circumferential surface that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between the cylindrical boss of the external gear and the through hole of the internal gear, that is formed in an annular shape with an outer circumferential surface center and an inner circumferential surface center eccentric to each other, that has a cam accommodating portion on the outer circumferential side, and that has a protrusion or a fitting recess on a side surface of a thickest portion or a thinnest portion in an eccentric direction; a pair of wedge-shaped cams that are accommodated in the cam accommodating portion and press the through hole of the internal gear and the bush to bring the bush into contact with the outer circumferential surface of the cylindrical boss of the external gear, thereby restricting relative rotation between the external gear and the internal gear, and that rotate the rotating shaft to slide the bush and the through hole of the internal gear or the bush and the cylindrical boss of the external gear, thereby allowing relative rotation between the external gear and the internal gear; an elastic body that biases the pair of wedge-shaped cams in a direction in which the pair of wedge-shaped cams simultaneously contact the bush and the through hole of the internal gear, The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the through hole of the internal gear and the bush is larger than a gap between the cylindrical boss of the external gear and the bush.

5. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having an outer peripheral surface on which external teeth are formed and an inner peripheral surface on which a through hole is formed coaxially with the axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on an inner circumferential surface and that can mesh with the external teeth, and that has a cylindrical boss that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between an inner periphery of the through hole of the external gear and an outer periphery of the cylindrical boss of the internal gear, that is formed in an annular shape with an eccentric center of the outer periphery and a center of the inner periphery, that has two spring accommodating portions that are formed on both sides of the thickest part of the annular shape and that have a gradually narrower gap in a direction away from the inner periphery, and that has a protrusion or a fitting recess on a side of the thickest part or the thinnest part in the eccentric direction; an elastic body having an annular portion and two ends rising from the annular portion so as to be bent at 90°, the two ends being accommodated in two spring accommodating portions and biased in directions away from each other, which presses the cylindrical boss of the internal gear and the bush to bring the bush into contact with the inner circumferential surface of the through hole of the external gear, thereby restricting relative rotation between the external gear and the internal gear, and rotating the rotating shaft to cause the bush and the cylindrical boss of the internal gear or the bush and the inner circumferential surface of the through hole of the external gear to slide, thereby allowing relative rotation between the external gear and the internal gear; Equipped with The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the cylindrical boss of the internal gear and the bush is larger than a gap between the through hole of the external gear and the bush.

6. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having an outer peripheral surface on which external teeth are formed and an inner peripheral surface on which a through hole is formed coaxially with the axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth that are at least one more than the external teeth on an inner circumferential surface and that can mesh with the external teeth, and that has a cylindrical boss that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into a cylindrical boss of the internal gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between an inner periphery of the through hole of the external gear and an outer periphery of the cylindrical boss of the internal gear, that is formed in an annular shape with the center of the outer periphery and the center of the inner periphery being eccentric, that has two spring accommodating portions that are formed on both sides of the thickest part of the annular shape and that have a space therebetween that gradually narrows in a direction away from the outer periphery, and that has a protrusion or a fitting recess on a side of the thickest part or the thinnest part in the eccentric direction; an elastic body having an annular portion and two ends rising from the annular portion so as to be bent at 90°, the two ends being accommodated in two spring accommodating portions and biased in directions away from each other, which presses the cylindrical boss of the internal gear and the bush to bring the bush into contact with the inner peripheral surface of the through hole of the external gear, thereby restricting relative rotation between the external gear and the internal gear, and rotating the rotating shaft to cause the bush and the through hole of the external gear or the bush and the cylindrical boss to slide, thereby allowing relative rotation between the external gear and the internal gear; Equipped with The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the cylindrical boss of the internal gear and the bush is smaller than a gap between the through hole of the external gear and the bush.

7. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an external gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the external gear having external teeth formed on an outer circumferential surface and a cylindrical boss coaxial with an axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth on an inner circumferential surface that are at least one more than the external teeth and that can mesh with the external teeth, and that has a through hole formed on the inner circumferential surface that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between the cylindrical boss of the external gear and the through hole of the internal gear, that is formed in an annular shape with an eccentric center of its outer circumferential surface and a center of its inner circumferential surface, that has two spring accommodating portions that are formed on both sides of the thickest part of the annular shape and that have a gradually narrower gap in a direction away from the inner circumference, and that has a protrusion or a fitting recess on a side of the thickest or thinnest part in the eccentric direction; an elastic body having an annular portion and two ends rising from the annular portion so as to be bent at 90°, the two ends being accommodated in two spring accommodating portions and biased in directions away from each other, which presses the cylindrical boss of the external gear and the bush to bring the bush into contact with the inner circumferential surface of the through hole of the internal gear, thereby restricting relative rotation between the external gear and the internal gear, and rotating the rotating shaft to cause the bush and the cylindrical boss of the external gear or the bush and the inner circumferential surface of the through hole of the internal gear to slide, thereby allowing relative rotation between the external gear and the internal gear; Equipped with The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, a gap between the through hole of the internal gear and the bushing is smaller than a gap between the cylindrical boss of the external gear and the bushing.

8. A seat reclining device that holds a seat back frame that constitutes a seat back so as to be tiltable relative to a seat cushion frame that constitutes a seat cushion, an external gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the external gear having external teeth formed on an outer circumferential surface and a cylindrical boss coaxial with an axial direction; an internal gear that is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, that has internal teeth on an inner circumferential surface that are at least one more than the external teeth and that can mesh with the external teeth, and that has a through hole formed on the inner circumferential surface that is coaxial with the axial direction; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and rotates either the external gear or the internal gear around a gear axis of the other gear; a bushing that is disposed between the cylindrical boss of the external gear and the through hole of the internal gear, that is formed in an annular shape with an eccentric center of its outer circumferential surface and a center of its inner circumferential surface, that has two spring accommodating portions that are formed on both sides of the thickest part of the annular shape and that have a space therebetween that gradually narrows in a direction away from the outer periphery, and that has a protrusion or a fitting recess on a side of the thickest or thinnest part in the eccentric direction; an elastic body having an annular portion and two ends rising from the annular portion so as to be bent at 90°, the two ends being accommodated in the two spring accommodating portions and biased in directions away from each other, which restricts relative rotation between the external gear and the internal gear by pressing the cylindrical boss of the external gear and the bush to bring the bush into contact with the inner peripheral surface of the through hole of the internal gear, and which allows relative rotation between the external gear and the internal gear by rotating the rotating shaft, causing the bush and the through hole of the internal gear or the bush and the cylindrical boss to slide; Equipped with The rotating shaft has a fitting recess or a protrusion that fits into the protrusion or the fitting recess of the bush so as to support the bush without a gap on both sides in the rotation direction in order to rotate the bush in the same manner when the rotating shaft rotates, A reclining device, wherein a gap between the through hole of the internal gear and the bush is larger than a gap between the cylindrical boss of the external gear and the bush.

9. 9. The reclining device according to claim 1, wherein the amount of eccentricity between the center of the bush relative to the outer peripheral surface and the center of the inner peripheral surface is greater than or equal to the amount of eccentricity between the center of the internal gear and the center of the external gear.

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