Reclining device

Abstract

The object of the present invention is to provide a reclining device that utilizes a Taumel mechanism and can effectively prevent liquid or paint from entering the inside of the device. [Solution] The reclining device of the present invention is characterized by comprising a driver 30 consisting of a Taumel mechanism, a resin driver 32 having a flat plate portion, a fitting portion and a cylindrical portion to which rotation from an external motor is transmitted, and a metal driver 34 fitted with the resin driver 32 to transmit the rotation of the resin driver into the Taumel mechanism, a ring 70 disposed between the flat plate portion of the resin driver 32 and an internal gear or an external gear, and a resin cap 80 that fixes the flat plate portion of the resin driver so as to pull the ring towards the internal gear.

Description

Technical Field

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

Background Art

[0002] The patentee has proposed a reclining device for a seat that holds a seat back so as to be tiltable with respect to a seat cushion, a first frame fixed to either the seat cushion or the seat back, a second frame fixed to the other of the seat cushion and the seat back, an external gear that is connected to the first frame and has external teeth formed on its outer peripheral surface and an external tooth boss portion coaxial with the axial direction on its inner peripheral surface, an internal gear that is connected to the second frame and has internal teeth formed on its outer peripheral surface that can mesh with the external teeth and a cylindrical boss portion coaxial with the axial direction on its inner peripheral surface, a rotating shaft that fits coaxially and rotatably onto the external gear and rotates either the external gear or the internal gear about the other gear's axis, a pair of wedge-shaped cams inserted between the cylindrical boss portion and the external tooth boss portion, simultaneously contacting the cylindrical boss portion side and the external tooth boss portion to restrict the rotation of the cylindrical boss portion and the external tooth boss portion, and sliding at least one of the cylindrical boss portion side and the external tooth boss portion side to allow the rotation of the cylindrical boss portion and the external tooth boss portion, a spring member that biases 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 as the rotating shaft rotates, extends in the axial direction, and has a pair of cam pressing wings provided with a taper on a contact surface that pushes the pair of wedge-shaped cams in a direction to be non-contact with at least one of the cylindrical boss portion side and the external tooth boss portion side, a leaf spring that presses the disk-shaped member against the pair of wedge-shaped cams and causes the tapered contact surface to contact the pair of wedge-shaped cams, and the biasing force is set weaker than that of the spring member (Patent Document 1).

[0003] This reclining device utilizes a Taumel mechanism. This device has a structure in which each component rotates or slides, with gaps between each component. Therefore, if the seat frame is painted while the reclining device is attached, paint can potentially seep in through these gaps. If this paint hardens and solidifies inside, it can impair the function of the reclining device. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-127210 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Therefore, the present invention has been made in view of these problems, and the object of the present invention is to provide a reclining device that utilizes a Taumel mechanism and can effectively prevent liquid or paint from entering the inside of the device. [Means for solving the problem]

[0006] To achieve the above-mentioned objectives, the present invention employs the following means.

[0007] The reclining device of the present invention is A seat reclining device that tiltably holds a seat back frame, which constitutes a seat back, with respect to a seat cushion frame, which constitutes a seat cushion, An external gear having external teeth formed on its outer surface, which is directly or indirectly attached to either the seat cushion frame or the seat back frame, An internal gear, which is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, and which has at least one more internal tooth on its inner circumferential surface than the external gear, It consists of a Taumel mechanism having, A seat reclining device that tiltably holds a seat back frame, which constitutes a seat back, with respect to a seat cushion frame, which constitutes a seat cushion, A driver comprising: a resin driver having a flat plate portion, a fitting portion, and a cylindrical portion to which rotation from an external motor is transmitted; and a metal driver fitted to the resin driver to transmit the rotation of the resin driver into the Taumel mechanism; A ring is positioned between the flat plate portion of the resin driver and the internal gear or external gear, The flat portion of the aforementioned resin driver is a resin cap that secures the ring so as to pull it towards the internal gear, It is characterized by having the following features.

[0008] By adopting this configuration, the gaps between the resin driver and the ring, and between the ring and the internal gear, are eliminated because the resin driver holds the ring in place by pulling it in with the resin cap, and since the resin driver is made of resin, the resin driver and ring can be slightly bent when pulled in by the resin cap, allowing for a strong hold and eliminating the gaps, thus preventing the intrusion of liquid or paint.

[0009] Furthermore, the reclining device according to the present invention may be characterized in that a taper is provided on the outer circumferential surface of the cylindrical portion of the resin driver. By adopting such a configuration, when the resin cap pulls in the resin driver, the taper around the cylindrical portion of the resin driver is pressed firmly against the inner circumferential surface of the cylindrical boss, thereby eliminating any gaps and preventing the intrusion of liquid or paint.

[0010] Furthermore, in the reclining device according to the present invention, an engagement groove may be formed on the outer circumferential surface of the cylindrical portion of the resin driver, and the resin cap may be provided with an engagement claw that engages with the engagement groove and a support piece that instructs the resin driver to be retracted. By adopting such a configuration, the resin cap can be effectively fixed in a retracted position.

[0011] Furthermore, in the reclining device according to the present invention, the cross-section of the ring may be bent in a V-shape, and the front and rear end faces may be made in the shape of a semicircle or semi-ellipse. The V-shape allows the ring to bend easily and to make contact with the flat plate portion and the internal gear or external gear in a pressing manner, and the semicircular or semi-ellipse shape of the end faces makes it easier to make contact along a line, thereby reducing the occurrence of gaps.

[0012] Furthermore, in the reclining device according to the present invention, The aforementioned Taumel mechanism is, An external gear is attached directly or indirectly to either the seat cushion frame or the seat back frame, having external teeth formed on its outer surface and a cylindrical boss at its center. An internal gear is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, and has at least one more internal tooth than the external gear on its inner circumferential surface, and has a through hole in its center, A bush is positioned between the cylindrical boss of the external gear and the through hole of the internal gear, having an opening in a part of the annular shape where the center of the outer surface and the center of the inner surface are eccentric, and which rotates when the driver is rotated. A pair of wedge-shaped cams are housed in a cam housing region formed between the bush and the cylindrical boss, and press the cylindrical boss of the internal gear against the bush, causing the bush to contact the inner circumferential surface of the through hole of the external gear, thereby restricting the relative rotation of the external gear and the internal gear, while rotating the driver causes the bush to slide against the cylindrical boss of the internal gear or the bush against the through hole of the external gear, thereby allowing the relative rotation of the external gear and the internal gear. The device may also be characterized by comprising an elastic body that biases a pair of wedge-shaped cams to contact the bush and the cylindrical boss simultaneously. Furthermore, the Taumel mechanism is, An external gear is attached directly or indirectly to either the seat cushion frame or the seat back frame, having external teeth formed on its outer surface and a through hole in its center. An internal gear is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, and has at least one more internal tooth on its inner circumferential surface than the external gear, and has a cylindrical boss at its center. A bush is positioned between the through hole of the external gear and the cylindrical boss of the internal gear, having an opening in a part of the annular shape where the center of the outer surface and the center of the inner surface are eccentric, and which rotates when the driver is rotated. A pair of wedge-shaped cams are housed in a cam housing region formed between the bush and the cylindrical boss, and by pressing the bush and bringing the bush into contact with the inner circumferential surface of the through hole of the internal gear, the relative rotation of the external gear and the internal gear is restricted, and by rotating the driver, the bush slides against the through hole of the internal gear or the bush against the cylindrical boss of the external gear, thereby allowing the relative rotation of the external gear and the internal gear. The device may also be characterized by comprising an elastic body that biases a pair of wedge-shaped cams to contact the bush and the cylindrical boss simultaneously. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram of a vehicle seat 200 to which a reclining device 100 according to the first embodiment is attached. [Figure 2] Figure 2 is a front view and an A-A cross-sectional view of the reclining device 100 according to the first embodiment. [Figure 3] Figure 3 is an exploded perspective view of the reclining device 100 according to the first embodiment. [Figure 4] Figure 4 is a perspective view and a front view of a resin driver 32 according to the first embodiment. [Figure 5] Figure 5 is a perspective view and a front view of a metal driver 34 according to the first embodiment. [Figure 6] Figure 6 is a perspective view and a cross-sectional view of a resin cap 80 according to the first embodiment. [Figure 7] Figure 7 is an exploded perspective view of the reclining device 100 according to the second embodiment.

Embodiments for Carrying out the Invention

[0014] Hereinafter, the reclining device 100 according to the embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a schematic diagram of a vehicle seat 200, Figure 2 is a front view and an A-A cross-sectional view of the reclining device 100, and Figure 3 is an exploded perspective view of the reclining device 100. Note that the following embodiments and drawings show an example of the present invention and do not limit the configuration of the present invention. Also, corresponding components in each figure are labeled with the same or similar reference numerals.

[0015] (First Embodiment) The reclining device 100 according to the first embodiment, as shown in Figure 1, is a device that is attached to the seat cushion 210 of a vehicle seat 200 and to the center of tilt of a seat back 220 which is tiltably attached to the seat cushion 210, and provides a tilting function to the seat back 220. Specifically, an external gear 10 and an internal gear 20 are attached directly or via other mounting plates 230 between a seat cushion frame located inside the seat cushion 210 and a seat back frame located inside the seat back 220. The seat cushion frame and seat frame are painted after each component, including the reclining device, is assembled.

[0016] The reclining device 100 according to the present invention mainly comprises, as shown in Figures 2 and 3, an external gear 10, an internal gear 20, a driver 30 consisting of a resin driver 32 and a metal driver 34, a bush 40, a pair of wedge-shaped cams 50a, 50b (50), and an elastic spring 60, a ring 70, a resin cap 80, and a plate cover 90.

[0017] As shown in Figure 3, the external gear 10 is formed in a disc shape, with external teeth 11 formed on its outer surface. A cylindrical boss 12 is formed in the center.

[0018] The internal gear 20 is a disc-shaped member having a larger diameter than the external gear 10, and has a recess into which the external gear 10 can be mounted. Internal teeth 21 are formed on the inner circumferential surface of this recess, and the number of teeth of the internal teeth 21 is set to be at least one more than the number of teeth of the external teeth 11 of the external gear 10. The internal teeth 21 and external teeth 11 mesh with the external gear 10 and the internal gear 20 respectively, with the centers of the external gear 10 and the internal gear 20 being eccentric, and the external gear 10 and the internal gear 20 form a differential gear, so that when the internal gear 20 rotates around the external teeth 11 once, it rotates by the difference in the number of teeth between the internal teeth 21 and the external teeth 11. For example, if the difference in the number of teeth between the external teeth 11 and the internal teeth 21 is 1, the external gear 10 will rotate by 1 tooth when it rotates around the internal gear 20 once. A through hole 22 is provided in the center of the internal gear 20. Furthermore, a ring arrangement section 24, where the ring 70 (described later) is placed, is formed on the front surface of the internal gear 20, and is lower than the front surface.

[0019] The driver 30 is a component that receives rotational force from an external motor of the vehicle seat to press and rotate the bush 40, which will be described later. The driver 30 is composed of two components: a resin driver 32 and a metal driver 34.

[0020] The resin driver 32 is made of synthetic resin and, as shown in Figure 4, comprises a flat plate portion 32a, a cylindrical portion 32c, and a fitting portion 32b. The flat plate portion 32a is formed in a circular flat shape and has the function of pressing the ring 70, as shown in the cross-sectional view AA of Figure 2. The cylindrical portion 32c is formed protruding from the center of the flat plate portion 32a and is inserted into the cylindrical boss 12 of the external gear 10. Furthermore, as shown in Figure 2, the cylindrical portion 32c has a taper on its outer circumference, and has a shape in which the outer diameter is larger at the root side than at the tip side. Near the tip of the cylindrical portion 32c, an engagement groove 32f is provided for engaging with the resin cap 80, which will be described later. In addition, motor serrations 32g are formed on the inside of the cylindrical portion 32c to receive the rotational force of the tilting motor. The fitting portion 32b is provided on the outer circumference of the cylindrical portion 32c on the flat plate portion 32a side, and by fitting with the metal screwdriver 34, it plays the role of synchronizing the rotation of the resin screwdriver 32 with that of the metal screwdriver 34. Serrations 32d are formed on the fitting portion 32b, and the shape of these serrations 32d is not particularly limited. In addition, a support portion 32e is provided on the outside of the fitting portion 32b, which is a structure that secures a gap for placing the spring 60 between the flat plate portion 32a and the metal screwdriver 34.

[0021] The metal screwdriver 34 is made of metal and, as shown in Figure 5A, has a ring-shaped annular portion 34a and a fitting portion 34b. The annular portion 34a is formed in a ring shape and, as shown in Figure 3, has the function of pressing against the end face 41 of the bush 40. For this purpose, an extended portion 34c is provided that can be inserted into the opening of the bush 40. The side surface 34d of the extended portion 34c contacts the end face 41 of the bush 40 and plays the role of pressing against it. The fitting portion 34b is provided on the inner circumference side of the annular portion 34a and, by fitting with the fitting portion 32b of the resin screwdriver 32, is structured to receive rotational force from the resin screwdriver 32.

[0022] The bush 40 is a component that is positioned together with the wedge-shaped cam 50 between the inner circumferential surface of the through hole 22 of the internal gear 20 and the cylindrical boss 12 of the external gear 10. The bush 40 is formed in a ring shape with a part of it open, and end faces 41 are provided at both ends. The bush 40 is driven by the rotation of the driver 30. Specifically, the side surface 34d of the extended portion 34c of the metal driver 34 presses against the end faces 41 of the bush 40, so that the bush 40 rotates in sync with the rotation of the driver 30.

[0023] A pair of wedge-shaped cams 50a and 50b (hereinafter collectively referred to as "wedge-shaped cams 50") are positioned between the inner circumferential surface of the bush 40 and the outer circumferential surface of the cylindrical boss 12 of the external gear 10 so as to contact both surfaces. As shown in Figure 3, these wedge-shaped cams 50a and 50b are formed symmetrically and have the following characteristics: The concave surface (inner surface) of the wedge-shaped cam 50 has the same curved shape as the outer circumferential surface of the cylindrical boss 12. On the other hand, the convex surface (outer surface) is formed so that its thickness gradually decreases from the opposing side. Furthermore, a cam housing region is provided on the inner circumferential surface of the bush 40 that matches the shape of the wedge-shaped cam 50. This cam housing region has a structure in which the gap gradually narrows from the opposing side, and the wedge-shaped cam 50 is fitted into this region.

[0024] As shown in Figure 3, the spring 60 has an annular portion 61 and ends 62a and 62b that rise up from the annular portion 61 at a 90° angle. The ends 62a and 62b are positioned on the end faces of the thickened portions of the wedge-shaped cams 50a and 50b, and play a role in biasing each wedge-shaped cam 50 in a direction that separates them from each other. This biasing force presses the external gear 10 against the internal gear 20, maintaining a state in which the gears mesh securely. Note that the spring 60 can also be made of other elastic materials such as rubber, as long as it can be configured to bias the wedge-shaped cam 50.

[0025] As shown in Figure 3, the ring 70 is a ring-shaped component made of synthetic resin. The cross-section of the ring 70 is made in a V-shape so that it can be easily bent by pressing on the front and back of the ring. In addition, the end faces on the front and back sides are made to have a semicircular or elliptical cross-section so that they can easily make gapless contact with the resin driver 32 and the internal gear 20.

[0026] The resin cap 80 is a component for fixing the resin driver 32, and as shown in Figure 6, it is a ring-shaped component provided with a plurality of engaging claws 81 and pressing pieces 83. The engaging claws 81 can engage with the engaging grooves 32f provided near the tip of the cylindrical portion 32c. The resin cap 80 is also provided with pressing pieces 83, which press the resin cap 80 toward the rear, thereby pressing against the external gear 10 and fixing the resin driver 32 in place.

[0027] The plate cover 90 is made of a metal plate formed in an annular shape, fixed to the outer end of the internal gear 20, and houses various components.

[0028] The reclining device 100 thus manufactured operates as follows: When no force is applied to the driver and the device is not being rotated, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in a direction that separates them, and are in contact with the bush 40 and the outer surface of the cylindrical boss 12 of the external gear 10. As a result, the relative motion of the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0029] When the resin screwdriver 32 is rotated from this locked state, the metal screwdriver 34 that is engaged with it also rotates. As this rotation occurs, the side surface 34d of the metal screwdriver pushes the end surface 41 of the bush 40, causing the bush 40 to rotate as well. The wedge-shaped cam 50 is in contact with the inner wall of the cam housing area of ​​the bush 40. Since a wedge angle is set on the inner wall of the cam housing area, the rotation of the bush 40 creates a gap between the wedge-angled inner wall and the wedge-shaped cam 50, causing the wedge to disengage. As a result, gaps are created between the bush 40 and the cylindrical boss 12 of the external gear 10 and between the bush 40 and the through hole 22 of the internal gear 20, allowing the external gear 10 to rotate relative to the internal gear 20. Accordingly, the biasing force of the spring 60 causes the wedge-shaped cam 50a to rotate to fill this gap. The wedge-shaped cam 50 rotates counterclockwise so as to slide together with the screwdriver 30 and the bush 40. Thus, the external gear 10, the internal gear 20, and the driver 30 constitute a differential gear mechanism. Both clockwise and counterclockwise rotations can be achieved in the same manner.

[0030] As shown in Figure 2, the reclining device 100 according to the present invention has three entry points for liquid or paint: P1 between the resin driver 32 and the ring 70, P2 between the ring 70 and the internal gear 20, and P3 between the inner circumference of the cylindrical boss 12 of the external gear and the outer surface of the cylindrical portion 32c of the resin driver 32. For P1 and P2, the resin driver 32 holds the ring 70 in place by pulling it in with the resin cap 80. In particular, since the resin driver 32 is made of resin, the resin driver 32 and the ring 70 can be held firmly in place by the resin cap 80 pulling them in, causing them to flex slightly, eliminating the gaps at P1 and P2 and preventing the entry of liquid or paint. On the other hand, for the entry point at P3, the resin cap 80 pulls in the resin driver 32, causing the taper around the cylindrical portion 32c of the resin driver 32 and the taper on the inner surface of the cylindrical boss 12 of the external gear 10 to press firmly against each other, eliminating the gap and preventing the entry of liquid or paint.

[0031] Furthermore, since the driver 30, which functions as a rotating shaft, is manufactured by dividing it into a resin driver 32 and a metal driver 34, the part that presses against the bush 40, which is subjected to a large force for rotation, can be pressed by metal, eliminating time lag and reducing damage. In addition, by combining it with the flexible resin driver 32, it is possible to absorb the movement caused by eccentricity between the external gear 10 and the internal gear 20.

[0032] Furthermore, the present invention is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

[0033] For example, in the embodiment described above, the external gear 10 is provided with a cylindrical boss 12 and the internal gear 20 is provided with a through hole 22. However, as shown in Figure 7, a Taumel mechanism may be adopted that has an external gear 10 having external teeth 11 formed on its outer surface and a through hole 15 in the center, and an internal gear 20 having a cylindrical boss 25 in the center.

[0034] Furthermore, one of the main features of the present invention is the prevention of liquid or paint ingress. The configuration of the Taumel mechanism other than the resin driver 32, metal driver 34, ring 70, and resin cap 80 involved in the ingress prevention mechanism is not particularly limited, and various known Taumel mechanisms can be selected and used. [Industrial applicability]

[0035] As shown in the embodiments described above, it is primarily industrially applicable as a reclining device for vehicle seats. [Explanation of Symbols]

[0036] 10…External gear, 11…External tooth, 12…Cylindrical boss, 15…Through hole, 20…Tooth gear, 21…Internal tooth, 22…Through hole, 24…Ring placement section, 25…Cylindrical boss, 30…Driver, 32…Resin driver, 32a…Flat plate section, 32b…Matching section, 32c…Cylindrical section, 32d…Serration, 32e…Support section, 32f…Engagement groove, 32g…Serration for motor, 34…Metal driver, 34a…Ring section, 34b…Matching section, 34c…Extended Installation part, 34d...side, 40...bush, 41...end face, 50...wedge-shaped cam, 50a...wedge-shaped cam, 50b...wedge-shaped cam, 60...spring, 61...annular part, 62a, 62b...end, 70...ring, 80...resin cap, 81...engaging claw, 83...pressing piece, 90...plate cover, 100...reclining device, 200...vehicle seat, 210...seat cushion, 220...seat back, 230...mounting plate

Claims

1. A seat reclining device that tiltably holds a seat back frame, which constitutes a seat back, with respect to a seat cushion frame, which constitutes a seat cushion, An external gear having external teeth formed on its outer surface, which is directly or indirectly attached to either the seat cushion frame or the seat back frame, An internal gear, which is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, and which has at least one more internal tooth on its inner circumferential surface than the external gear, It consists of a Taumel mechanism having, A seat reclining device that tiltably holds a seat back frame, which constitutes a seat back, with respect to a seat cushion frame, which constitutes a seat cushion, A driver comprising: a resin driver having a flat plate portion, a fitting portion, and a cylindrical portion to which rotation from an external motor is transmitted; and a metal driver fitted to the resin driver to transmit the rotation of the resin driver into the Taumel mechanism; A ring is positioned between the flat plate portion of the resin driver and the internal gear or external gear, The flat portion of the aforementioned resin driver is a resin cap that secures the ring so as to pull it towards the internal gear, A reclining device characterized by having the following features.

2. The reclining device according to claim 1, characterized in that a taper is provided on the outer circumferential surface of the cylindrical portion of the resin driver.

3. An engagement groove is formed on the outer circumferential surface of the cylindrical portion of the resin driver. The reclining device according to claim 1, characterized in that the resin cap is provided with an engaging claw that engages with the engaging groove and a pressing piece that presses to pull in the resin driver.

4. The reclining device according to claim 1, characterized in that the cross-section of the ring is in the shape of a V, and the front and rear end faces are made in the shape of a semicircle or semi-ellipse.

5. The aforementioned Taumel mechanism is, An external gear is attached directly or indirectly to either the seat cushion frame or the seat back frame, having external teeth formed on its outer surface and a cylindrical boss at its center. An internal gear is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, and has at least one more internal tooth than the external gear on its inner circumferential surface, and has a through hole in its center, A bush is positioned between the cylindrical boss of the external gear and the through hole of the internal gear, having an opening in a part of the annular shape where the center of the outer surface and the center of the inner surface are eccentric, and which rotates when the driver is rotated. A pair of wedge-shaped cams are housed in a cam housing region formed between the bush and the cylindrical boss, and press the cylindrical boss of the internal gear against the bush, causing the bush to contact the inner circumferential surface of the through hole of the external gear, thereby restricting the relative rotation of the external gear and the internal gear, while rotating the driver causes the bush to slide against the cylindrical boss of the internal gear or the bush against the through hole of the external gear, thereby allowing the relative rotation of the external gear and the internal gear. The reclining device according to claim 1, further comprising an elastic body that biases a pair of wedge-shaped cams to contact the bush and the cylindrical boss simultaneously.

6. The aforementioned Taumel mechanism is, An external gear is attached directly or indirectly to either the seat cushion frame or the seat back frame, having external teeth formed on its outer surface and a through hole in its center. An internal gear is directly or indirectly attached to the other of the seat cushion frame and the seat back frame, and has at least one more internal tooth than the external gear on its inner circumferential surface, and has a cylindrical boss at its center, A bush is positioned between the through hole of the external gear and the cylindrical boss of the internal gear, having an opening in a part of the annular shape where the center of the outer surface and the center of the inner surface are eccentric, and which rotates when the driver is rotated. A pair of wedge-shaped cams are housed in a cam housing region formed between the bush and the cylindrical boss, and by pressing the bush and bringing the bush into contact with the inner circumferential surface of the through hole of the internal gear, the relative rotation of the external gear and the internal gear is restricted, and by rotating the driver, the bush slides against the through hole of the internal gear or the bush against the cylindrical boss of the external gear, thereby allowing the relative rotation of the external gear and the internal gear. The reclining device according to claim 1, further comprising an elastic body that biases a pair of wedge-shaped cams to contact the bush and the cylindrical boss simultaneously.

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