JP7634373B2 - Reclining device - Google Patents

Description

The present invention relates to a reclining device.

Various seat reclining devices that hold the seat back tiltably relative to the seat cushion have been proposed (for example, Patent Document 1). In such a reclining device, as shown in FIG. 7, there is a reclining device 300 that includes an external gear 310 having a through hole 312 on the inner circumferential surface that is coaxial with the axial direction, an internal gear 320 having internal teeth on the outer circumferential surface that can mesh with the external teeth and a cylindrical boss portion on the inner circumferential surface that is coaxial with the axial direction, a rotating shaft 330 that is coaxially and rotatably fitted to the external gear 310 and rotates either the external gear 310 or the internal gear 320 around the gear shaft of the other, a bush 340 provided between the through hole 312 and the cylindrical boss 322, and a pair of wedge-shaped cams 350 provided on the bush 340 that simultaneously contact the cylindrical boss 322 side and the bush 340 to restrict the rotation of the cylindrical boss 322 and the bush 340, and slide at least one of the cylindrical boss 322 and the bush 340 to allow the cylindrical boss 322 and the bush 340 to rotate.

In a reclining device 300 configured in this way, when the external gear 310 and the internal gear 320 are eccentrically meshed, a gap is required between the bush 340 on the opposite side to the meshed side and the through hole of the external gear 310 (μ) because the external gear 310 needs to move slightly up and down relative to the internal gear 320 in order to rotate, and it is unavoidable that a gap will occur due to manufacturing errors, etc.

However, when sliding, the bush is in contact all around, so the force can be transmitted efficiently and it acts as a bearing, stabilizing the sliding and ensuring smooth rotation.

JP 2019-127210 A

The present invention was made in consideration of these problems, and aims to provide a reclining device that, when locked, can form a gap between the bush and the gear on the side opposite to where the external gear and internal gear mesh, allowing movement in an eccentric direction due to the meshing of the external gear and internal gear, and that reduces this gap during sliding, allowing contact around the entire circumference of the bush, making it possible to transmit force from any direction of 360° and stabilizing sliding.

To achieve the above-mentioned objectives, the present invention adopts the following measures.

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 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 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 cylindrical boss that is coaxial with the axial direction;
a first bush disposed between the inner circumference of the through hole of the external gear and the outer circumference of the cylindrical boss of the internal gear, formed in an annular shape with the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and having a protrusion having a hole for an elastic body on a front surface; and a second bush disposed on top of the first bush such that the protrusion is disposed in the open portion of the annular shape with a hole for an elastic body on a front surface, the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and the second bush is disposed on top of the first bush such that the protrusion is disposed in the open portion of the annular shape,
a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear and has a bush pressing portion that protrudes into the annular opening of the second bush;
an elastic body fixed to an elastic body hole of the first bush and an elastic body for biasing the first bush and the second bush,
The first bush and the second bush are arranged so that, in a locked state, a gap is provided between the cylindrical boss and the cylindrical boss on the opposite side to the side where the external gear and the internal gear mesh, and are arranged so that, when the rotating shaft is rotated and put into a sliding state, the gap between the external gear and the cylindrical boss on the opposite side to the side where the internal gear meshes is reduced.

By adopting such a configuration, when locked, a gap can be formed between the bush and the gear on the side opposite to the side where the external gear and internal gear mesh, and when sliding, the bush rotates, the part of the bush used changes between when locked and when sliding, the gap relationship changes, and gaps are provided in different positions in the first bush and the second bush, so that the first bush or the second bush has more contact surfaces around the entire circumference, resulting in a structure that can withstand loads in all directions. Therefore, the bush can provide bearing support around almost the entire circumference. Therefore, even if an external force is applied from any direction of 360°, the bush can withstand the force, and sliding can be stabilized.

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 an outer peripheral surface on which external teeth are formed and an inner peripheral surface on which a cylindrical boss 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 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 that is coaxial with the axial direction;
a first bush disposed between the inner circumference of the through hole of the internal gear and the outer circumference of the cylindrical boss of the external gear, formed in an annular shape with the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and having a protrusion having a hole for an elastic body on its back surface; and a second bush, formed in a substantially arch shape with a hole for an elastic body on its back surface, with the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically partially opened, and disposed on top of the first bush so that the protrusion is located in the open portion;
a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and has a bush pressing portion that protrudes into the annular opening of the second bush;
an elastic body fixed to an elastic body hole of the first bush and an elastic body for biasing the first bush and the second bush, respectively;
The first bush and the second bush are arranged so that, in a locked state, a gap is provided between the cylindrical boss and the cylindrical boss on the opposite side to the side where the external gear and the internal gear mesh, and are arranged so that, when the rotating shaft is rotated and put into a sliding state, the gap between the cylindrical boss on the opposite side to the side where the external gear and the internal gear mesh is reduced.

By adopting such a configuration, when locked, a gap can be formed between the bush and the gear on the side opposite to the side where the external gear and internal gear mesh, and when sliding, the bush rotates, the part of the bush used changes between when locked and when sliding, the gap relationship changes, and gaps are provided in different positions in the first bush and the second bush, so that the first bush or the second bush has more contact surfaces around the entire circumference, resulting in a structure that can withstand loads in all directions. Therefore, the bush can provide bearing support around almost the entire circumference. Therefore, even if an external force is applied from any direction of 360°, the bush can withstand the force, and sliding can be stabilized.

In addition, in the reclining device according to the present invention,
The major axes of the ellipses of the first bushing and the second bushing may be arranged such that, when locked, one of them is out of phase with respect to the eccentric direction of the external gear and the internal gear by +3° to +12° and the other is out of phase with respect to the eccentric direction of the external gear and the internal gear by -3° to -12°.

By setting this range, it is possible to ensure that as large a surface area as possible contacts the entire circumference of the cylindrical boss when sliding.

FIG. 1 is a schematic diagram of a vehicle seat 200 to which a reclining device 100 according to the first embodiment is attached. FIG. 2 is a front view showing the internal structure of the reclining device 100 according to the first embodiment. FIG. 3 is an exploded perspective view of the reclining device 100 according to the first embodiment. FIG. 4 is a cross-sectional view taken along line AA of FIG. 2 according to the first embodiment. FIG. 5 is a schematic diagram illustrating the first bush 41 and the second bush 45 according to the first embodiment. FIG. 6 is an exploded perspective view of the reclining device 100 according to the second embodiment. FIG. 7 is a front view of a conventional reclining device 300. As shown in FIG.

The reclining device 100 according to an embodiment of the present invention will be described in detail below 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 A-A in FIG. 2. Note that the embodiments and drawings described below are intended to exemplify some of the embodiments of the present invention, and are not to be used to limit the present invention to these configurations. Note that corresponding components in each drawing are denoted by the same or similar reference numerals.

First Embodiment
1, the reclining device 100 according to the first embodiment is a device that is attached to a seat cushion 210 of a vehicle seat 200 and a center position of the tilt of a seat back 220 that is tiltably attached to the seat cushion 210, and that 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 a "mounting plate or the like").

As shown in Figures 2 and 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 spring 60 as an elastic body, a spring cover 70, and a plate cover 80. Note that in Figure 2, the spring cover 70 and the plate cover 80 are omitted to make the internal structure easier to see.

As shown in FIG. 3, the external gear 10 is formed in a disk shape, with external teeth 11 formed on the outer periphery and a cylindrical through hole 12 formed in the center. The external gear 10 has a protrusion 13 on the front surface 10b, which 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.

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 attached inside, and the internal teeth 21 are formed on the inner peripheral surface 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 has a protrusion 23 on its back surface, which is fitted into a fitting hole provided in a mounting plate or the like 230 and attached by welding or the like.

The rotating shaft 30 is coaxially inserted into the cylindrical boss 22 of the internal gear 20 so as to be freely rotatable. 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 the tilt motor. The rotating shaft 30 is further provided with a bush pressing portion 32 for rotating the first bush 41 and the second bush 45, which will be described later.

The bush 40 is a member disposed between the outer circumferential surface 22a of the cylindrical boss 22 of the internal gear 20 and the through hole 12 of the external gear 10, and is formed by stacking a first bush 41 and a second bush 45 as shown in FIG. 3.

As shown in Fig. 2B, the first bush 41 is formed in a ring shape in which the center _C3 of the inner peripheral surface 41a is offset from the center _C4 of the outer peripheral surface 41b. The outer peripheral surface 41b is formed in a circular shape when viewed from the front, and the inner peripheral surface 41a is formed in an elliptical shape. A protrusion 41d having an elastic body hole 41c is provided on the front surface of the first bush 41.

As shown in FIG. 2C, the second bush 45 is eccentric in that the center of the inner circumferential surface 45a is offset from the center of the outer circumferential surface 45b, similar to the first bush 41. The outer circumferential surface 45b is circular in front view, and the inner circumferential surface 45a is elliptical in front view, and is formed into a generally arch-like shape with a portion of the annular shape opened. The second bush 45 is placed on top of the first bush 41 so that the protrusion 41d is located in the open portion. The second bush 45 has an elastic body hole 45c on the front side.

The spring 60 is made of an elastic body, and as shown in FIG. 3, 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 rotating shaft 30, the first bush 41, the second bush 45, and the spring 60 are arranged as the reclining device 100 as follows. If the external gear 10 and the internal gear 20 are locked in a state in which the external gear 10 is eccentric in the direction of the arrow D as shown in FIG. 2A, the first bush 41 contacts the cylindrical boss 22 at a position α other than the line of the arrow D that passes through the center of the external gear 10 in the eccentric direction as shown in FIG. 2B, thereby locking the external gear 10 and the internal gear 20, and at least at a position β on the line of the arrow D of the cylindrical boss 22 on the opposite side to the eccentric direction, a gap is provided between the cylindrical boss 22 and the external gear 10, and the external gear 10 can move in the direction of the arrow D and in the opposite direction. The second bush 45 has the protrusion 41d of the first bush 41 disposed in the open ring portion, and as shown in FIG. 2C, the second bush 45 contacts the cylindrical boss 22 at a position γ other than on the line of the arrow D to lock the external gear 10 and the internal gear 20, and has an open ring portion at least at a position δ opposite to the direction of the arrow D of the cylindrical boss 22, and a gap ε is also provided between the end 45d of the second bush 45 and the cylindrical boss 22, so that the external gear 10 can move in the direction of the arrow D and in the opposite direction. Therefore, the external gear 10 and the internal gear 20 can effectively mesh the external teeth 11 and the internal teeth 21. The rotating shaft 30 is attached so that the bush pressing portion 32 is disposed between the protrusion 41d of the first bush 41 and one of the ends of the second bush 45. The elastic body hole 45c of the second bush 45 is provided near the side adjacent to the protrusion 41d of the first bush 41. The spring 60 has ends 62a and 62b inserted into the elastic body hole 41c of the first bush 41 and the elastic body hole 45c of the second bush 45, and as shown in FIG. 2A, the first bush 41 and the second bush 45 are biased so as to rotate in opposite directions (in the direction of arrow E in FIG. 2A). This biasing force brings them into strong contact with the cylindrical boss 22 at positions α and γ, respectively, and maintains the locked state of the external gear 10 and the internal gear 20.

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 that can hold the spring 60.

The plate cover 80 is made of a metal plate formed into an annular shape and is fixed to the outer end of the internal gear 20 by welding or other means, and has the function of restricting the axial movement of the external gear 10.

The reclining device 100 thus manufactured operates as follows. As described above, in the state shown in FIG. 2 where no force is applied to the rotating shaft 30 and it is not rotating, the first bush 41 and the second bush 45 are biased by the spring 60 so that they rotate in opposite directions. This bias brings them into strong contact with the cylindrical boss 22 at positions α and γ, respectively, locking the relative movement of the external gear 10 and the internal gear 20, and the seat back 220 is in a locked state.

When the rotating shaft 30 is rotated clockwise from this locked state, for example, in FIG. 2, the bush pressing portion 32 of the rotating shaft 30 presses the end 45e of the second bush 45, and the second bush 45 rotates clockwise, and the opposite end 45d of the second bush 45 presses the protrusion 41d of the first bush 41, so that the first bush 41 also rotates clockwise. This rotation of the first bush 41 and the second bush 45 creates gaps at the locked positions α and γ, and the rotating shaft 30 and the bush 40 rotate clockwise relative to the internal gear 20. As a result, gaps are 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 external gear 10 rotates clockwise to fill the gaps due to the biasing force of the spring 60, and the external gear 10, the internal gear 20, and the rotating shaft 30 form a differential gear mechanism. At this time, the bush 40 rotates during sliding, and the portion of the bush 40 used during locking and sliding changes, the gap relationship changes, and gaps are provided at different positions in the first bush 41 and the second bush 45, so that the first bush 41 or the second bush 45 comes into contact with a large surface area over the entire circumference, resulting in a structure that can receive loads in all directions. Therefore, 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 is moved in the direction of the external force or the reaction force, but the bush is sandwiched perpendicularly between the outer circumferential surface 22a of the cylindrical boss 22 of the internal gear 20 and the through hole 12 of the external gear 10 in the direction of the attempted movement, and the component force components are minimized to function as a bearing, so that sliding is stabilized and smooth rotation can be ensured. When the rotating shaft 30 is rotated counterclockwise, the bush pressing portion 32 presses the protrusion 41d of the first bush 41, and the protrusion 41d presses the end 45d of the second bush 45, thereby rotating the shaft counterclockwise. The bush 40 rotates during sliding, and the parts of the bush 40 used during locking and sliding change, the gap relationship changes, and gaps are provided in different positions between the first bush 41 and the second bush 45, just like clockwise rotation. In this way, in order to provide a gap between the cylindrical boss 22 at position β on the opposite side to the eccentric direction D when locked, and to make contact with the cylindrical boss 22 over the entire circumference over as large a surface as possible when sliding, it is advisable to arrange the first bush 41 and the second bush 45 so that, when locked, an angle θ ₁ between the major axis 41 f of the ellipse of the first bush 41 and the eccentric direction of the external gear 10 and the internal gear (direction of arrow D) and an angle θ ₂ between the major axis 45 f of the ellipse of the second bush 45 and the eccentric direction of the external gear 10 and the internal gear (direction of arrow D) are shifted in phase by +3° to +12° on one side and -3° to -12° on the other side, as shown in FIGS. 2B and 2C .

Second Embodiment
The reclining device 100 according to the second embodiment is shown in Fig. 6. The reclining device 100 according to the second 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 spring cover 70 for preventing the rotating shaft 30, the bush 40, and the spring 60 from moving in the axial direction is provided on the rear side of the internal gear 20, and this spring cover 70 is provided with a protrusion 71 that fits into a fitting hole of the mounting plate or the like 230. On the other hand, the plate cover 80 is made of a metal plate formed in an annular shape, is arranged on the front 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.

The rotating shaft 30, the bush 40, and the spring 60 are manufactured symmetrically with respect to 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 such that the cylindrical boss 14 is inserted into the inner peripheral surface 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 is provided with a bush pressing portion 32 as in the first embodiment, so that the bush 40 can be rotated either clockwise or counterclockwise. The bush 40 is formed of a first bush 41 and a second bush 45, and the outer peripheral surface is formed in a circular shape, and the inner peripheral surface is formed in an elliptical shape, as in the first embodiment.

The reclining device 100 thus manufactured operates as follows. As described above, when no force is applied to the rotating shaft 30 and it is not rotating, the first bush 41 and the second bush 45 are biased by the spring 60 so as to rotate in opposite directions. This bias brings the first bush 41 and the second bush 45 into strong contact with the cylindrical boss 22, locking the relative movement of the external gear 10 and the internal gear 20, and the seat back 220 is in a locked state.

When the rotating shaft 30 is rotated clockwise from this locked state, the bush pressing portion 32 of the rotating shaft 30 presses the end 45e of the second bush 45, and the second bush 45 rotates clockwise, and the opposite end 45d of the second bush 45 presses the protrusion 41d of the first bush 41, causing the first bush 41 to rotate clockwise. This rotation of the first bush 41 and the second bush 45 creates a gap at the locked position, and the rotating shaft 30 and the bush 40 rotate clockwise relative to the internal gear 20. As a result, a gap is created between the bush 40 and the cylindrical boss 14 of the external gear 10 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. As a result, the external gear 10 rotates clockwise to fill the gap due to the biasing force of the spring 60, and the external gear 10, the internal gear 20, and the rotating shaft 30 form a differential gear mechanism. At this time, the bush 40 rotates during sliding, and the portion of the bush 40 used during locking and sliding changes, and the gap relationship changes. Since the first bush 41 and the second bush 45 have gaps at different positions, the first bush 41 or the second bush 45 has a large surface area in contact with the entire circumference, resulting in a structure that can receive loads in all directions. Therefore, 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 is moved in the direction of the external force or the reaction force, but the bush is sandwiched perpendicularly to the outer circumferential surface 14a of the cylindrical boss 14 of the external gear 10 and the through hole 25 of the internal gear 20 in the direction of the movement, and the component force components are minimized to serve as a bearing, so that sliding is stabilized and smooth rotation can be ensured. The relationship when the rotating shaft 30 is rotated counterclockwise is the same as in the first embodiment. Thus, in order to provide a gap between the cylindrical boss 22 at position β on the opposite side of the eccentric direction D when locked, and to contact the cylindrical boss 22 over the entire circumference with as large a surface as possible when sliding, it is advisable to arrange the angle θ1 between the major axis 41f of the ellipse of the first bush 41 and the eccentric direction of the external gear 10 and the internal gear (direction of arrow D) and the angle θ2 between the major axis 45f of the ellipse of the second bush 45 and the eccentric direction of the external gear 10 and the internal gear (direction of arrow D) so that one is out of phase with the other by +3° to +12° and the other by -3° to -12°.

The present invention is not limited to the above-described embodiment, and may be implemented in various forms within the technical scope of the present invention.

As shown in the above-mentioned embodiment, it can be used industrially primarily as a reclining device for vehicle seats.

10...external gear, 10b...front, 11...external teeth, 12...through hole, 13...projection, 14...cylindrical boss, 14a...outer surface, 20...internal gear, 21...internal teeth, 22...cylindrical boss, 22a...outer surface, 23...projection, 25...through hole, 30...rotating shaft, 31...serration, 32...bush pressing portion, 40...bush, 41...first bush, 41a...inner surface, 41b...outer surface, 41c...hole for elastic body, 41d...projection, 4 1f...long shaft, 45...second bush, 45a...inner circumferential surface, 45b...outer circumferential surface, 45c...elastic body hole, 45d...end, 45e...end, 45f...long shaft, 60...spring, 61...annular portion, 62a, 62b...end, 70...spring cover, 71...projection, 80...plate cover, 100...recliner, 200...vehicle seat, 210...seat cushion, 220...seat back, 230...mounting plate

Claims (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 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 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 cylindrical boss formed thereon that is coaxial with the axial direction;
a first bush disposed between the inner circumference of the through hole of the external gear and the outer circumference of the cylindrical boss of the internal gear, formed in an annular shape with the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and having a protrusion having a hole for an elastic body on a front surface; and a second bush disposed on top of the first bush such that the protrusion is disposed in the open portion of the annular shape with a hole for an elastic body on a front surface, the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and the second bush is disposed on top of the first bush such that the protrusion is disposed in the open portion of the annular shape,
a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear and has a bush pressing portion that protrudes into the annular opening of the second bush;
an elastic body fixed to an elastic body hole of the first bush and an elastic body for biasing the first bush and the second bush,
The first bush and the second bush are biased by the elastic body so as to rotate in opposite directions, and come into contact with the cylindrical boss due to this biasing.In a locked state in which the relative movement of the external gear and the internal gear is locked , the elastic body biases the first bush and the second bush such that a gap is provided between the cylindrical boss and the cylindrical boss on the opposite side to the side where the external gear and the internal gear are meshed, and when the rotating shaft is rotated and put into a sliding state, the gap between the cylindrical boss on the opposite side to the side where the external gear and the internal gear are meshed is reduced.This reclining device is characterized in that 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 cylindrical boss 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 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 that is coaxial with the axial direction;
a first bush that is disposed between the inner circumference of the through hole of the internal gear and the outer circumference of the cylindrical boss of the external gear, that is formed in an annular shape with the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and that has a protrusion having a hole for an elastic body on its back surface; and a second bush that has a hole for an elastic body on its back surface, that is formed in a substantially arch shape with the center of the outer circumferential surface formed in a circle and the center of the inner circumferential surface formed in an ellipse eccentrically, and that is disposed on top of the first bush so that the protrusion is disposed in the open portion of the annular shape,
a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear and has a bush pressing portion that protrudes into the annular opening of the second bush;
an elastic body fixed to an elastic body hole of the first bush and an elastic body for biasing the first bush and the second bush, respectively;
The first bush and the second bush are biased by the elastic body so as to rotate in opposite directions, and come into contact with the cylindrical boss due to this biasing.In a locked state in which the relative movement of the external gear and the internal gear is locked, the first bush and the second bush are arranged so that a gap is provided between the cylindrical boss and the cylindrical boss on the opposite side to the side where the external gear and the internal gear are meshed due to the biasing of the elastic body, and when the rotating shaft is rotated and put into a sliding state, the gap between the cylindrical boss on the opposite side to the side where the external gear and the internal gear are meshed is reduced.This reclining device is characterized in that The reclining device according to claim 1 or 2, characterized in that, in a locked state , the major axes of the ellipses of the first bush and the second bush are arranged so that, relative to the eccentric direction of the external gear and the internal gear, one of them is out of phase with each other by +3° to +12° and the other is out of phase with each other by -3° to -12°.

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