Reclining device

Abstract

To provide a configuration that is capable of securing a necessary contact area between a cum surface of a cam and an inside end surface of a lock gear even when the cam is displaced relatively in an axial direction with respect to the lock gear.SOLUTION: On a surface facing lock gears 61, 62 and a cam 70 of a base plate 30, a circular recess 36 into which one side in an axial direction of the cam 70 enters is formed. The cam 70 is formed so that length T1 in the axial direction of the cam surface 72 is longer than length T2 in the axial direction of inside end surfaces 61c, 62c in the lock gears 61, 62.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a reclining device that adjusts the tilt angle between a first member and a second member that tilt relative to one another. [Background technology]

[0002] A conventional reclining device that adjusts the tilt angle between a first member and a second member that tilt relative to one another is disclosed in Patent Document 1. This reclining device is configured to switch between a locked state in which each lock gear meshes with a gear plate and an unlocked state in which the meshing is released, depending on the state of contact between a cam that rotates in response to the operation of a reclining operation lever and four lock gears.

[0003] In addition, between the lock gear and the fixed guide, a slidable movable guide is interposed, and the width of each movable guide is gradually narrowed from the outer end to the inner end, and the sliding surface of the movable guide on the lock gear side is parallel to the moving direction of the lock gear, and the sliding surface on the fixed guide side is inclined with respect to the sliding surface on the lock gear side. A spring is engaged with each movable guide, and the spring biases the movable guide inwardly of the base plate. Therefore, the movable guide is always wedged between the lock gear and the fixed guide, and the fixed guide, the lock gear, and the movable guide are mutually engaged, and the gap between each member disappears. This reliably eliminates backlash in the front-rear direction of the seat back, enabling reliable locking and unlocking. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-056397 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand for thinner reclining devices (shorter axial length), and efforts are being made to shorten the axial length of each component that makes up the reclining device. To achieve this, it is necessary to make the axial length of the cam and lock gear shorter than that of conventional products.

[0006] However, when the axial lengths of the cam and the lock gear are shortened, the contact area (contact width in the axial direction) between the cam surface on the outer periphery of the cam and the inner end face (end face on the inner periphery) of the lock gear becomes smaller. The cam and the lock gear are housed in a housing space formed by a gear plate and a base plate together with a cam lever, a spring, etc., and each part in this housing space is allowed to move (shift) to a certain extent by design. Therefore, when the cam shifts in the axial direction relative to the lock gear, the contact area becomes even smaller. When the cam presses the lock gear outward in a locked state with the contact area reduced in this way, the stress acting on the contact area becomes large, and there is a risk of pressure loss or the like at the contact site.

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a configuration that can ensure the necessary contact area between the cam surface of the cam and the inner end face of the lock gear even if the cam is displaced in the axial direction relative to the lock gear. [Means for solving the problem]

[0008] In order to achieve the above object, the invention of claim 1 described in the claims is as follows: A reclining device (20) for adjusting a tilt angle between a first member (11, 11a) and a second member (12, 12a) that tilt relative to one another, comprising: A base plate (30) attached to the first member; a gear plate (40) attached to the second member and assembled to be rotatable relative to the base plate, the gear plate having internal teeth (41); a lock gear (61, 62) assembled to be guided radially slidably by utilizing guide surfaces (33a, 33b, 34a, 34b) formed on the base plate, the lock gear having external teeth (61a, 62a) meshable with the internal teeth; a cam (70) that, when rotated about a predetermined rotation axis, abuts against an inner end surface (61c, 62c) of the lock gear from the radially inner side at a cam surface (72), thereby causing the external teeth to mesh with the internal teeth; a biasing member (80) that biases the cam in a direction in which the external teeth mesh with the internal teeth; a release member (90) capable of releasing the meshing between the external teeth and the internal teeth by rotating the cam against the biasing force of the biasing member; Equipped with a recess into which one axial side of the cam fits, is formed on a surface of the base plate facing the lock gear and the cam; The cam is characterized in that the cam surface has an axial length longer than the axial length of the inner end face of the lock gear. The symbols in parentheses above indicate the corresponding relationship with the specific means described in the embodiments described later. Effect of the Invention

[0009] In the invention of claim 1, a recess is formed on the surface of the base plate facing the lock gear and the cam, into which one axial side of the cam fits, and the cam is formed so that the axial length of the cam surface is longer than the axial length of the inner end surface of the lock gear. As a result, even if the cam shifts to the other axial side relative to the lock gear, the part of the cam surface that fit into the recess comes into contact with the inner end surface of the lock gear, so that the necessary contact area can be secured between the cam surface of the cam and the inner end surface of the lock gear.

[0010] In the invention of claim 2, the cam is formed so that the axial length of the cam surface is equal to the sum of the axial length of the inner end surface and the depth of the recess. As a result, even if one axial side of the cam enters so as to contact the bottom surface of the recess, the other axial side of the cam surface and the other axial side of the inner end surface are flush with each other, so that the necessary contact area can be secured between the cam surface of the cam and the inner end surface of the lock gear. [Brief description of the drawings]

[0011] [Figure 1] 1 is a side view showing an outline of the configuration of a vehicle seat on which a reclining device of the present invention is installed. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] 3 is a cross-sectional view taken along a line X1-X1 shown in FIG. 2. [Diagram 5] 3 is a cross-sectional view taken along line X2-X2 of FIG. 2. [Figure 6] 10 is an explanatory diagram illustrating the relationship between the axial length of a cam surface of a cam, the axial length of an inner end face of a lock gear, and the depth of a recess in a base plate, using an enlarged cross section. FIG. [Figure 7] Figure 7(A) is an explanatory diagram illustrating a state in which the cam is in contact with the bottom surface of the recess in the base plate on one axial side, and Figure 7(B) is an explanatory diagram illustrating a state in which the cam etc. is shifted to the other axial side relative to Figure 7(A). BEST MODE FOR CARRYING OUT THEINVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a reclining device according to the present invention will be described with reference to the drawings. As shown in FIG. 1, a vehicle seat 10 equipped with a reclining device 20 of the present invention has as its main components a seat cushion 11 and a seat back 12, with a seat bracket (lower bracket) 11a fixed to the seat cushion 11 and a seat back bracket (upper bracket) 12a fixed to the seat back 12.

[0013] The lower bracket 11a and the upper bracket 12a are fixed to portions of the round reclining unit 21 that rotate relative to each other, and are thereby connected to each other so as to be capable of rotating relative to each other. This makes it possible to adjust the tilt angle of the seat back 12 relative to the seat cushion 11. The seat cushion 11 and the lower bracket 11a can be an example of a "first member," and the seat back 12 and the upper bracket 12a can be an example of a "second member."

[0014] A reclining operation lever 23 is attached to a center shaft 22 in the center of the round reclining unit 21. The round reclining unit 21, the center shaft 22, and the reclining operation lever 23 constitute the reclining device 20. When the reclining operation lever 23 is pulled upward, the reclining device 20 is unlocked, and the tilt angle of the seat back 12 can be adjusted. Here, the range of angle A shown in FIG. 1 when the seat back 12 is tilted backward is the tilt adjustment range in which the seat back 12 is locked at the angle position when the reclining operation lever 23 is released, and the range of angle B shown in FIG. 1 when the seat back 12 is tilted forward is the free rotation range corresponding to the lock-free state in which the unlocked state continues even when the reclining operation lever 23 is released. As can be seen from FIG. 1, the seat back 12 can be rotated from a forward tilt position in which it contacts the seat cushion 11 to a backward tilt position in which it is flat against the seat cushion 11. The structure of such a reclining device 20 will be described below.

[0015] 2 and 3, the round reclining unit 21 is configured by overlapping a substantially disc-shaped base plate 30 and a substantially bowl-shaped gear plate 40 and assembling a cover bracket 50, thereby holding the base plate 30 and the gear plate 40 rotatably relative to each other and suppressing relative movement in the axial direction. For convenience, the center shaft 22 and the reclining operation lever 23 are not shown in Figures 2 and 3, and in Figures 4 and 5, only the vicinity of the internal teeth 41 of the gear plate 40 is shown, with the cover bracket 50 not shown.

[0016] A cavity (space) C is formed between the base plate 30 and the gear plate 40. As shown in Figures 2 to 5, a total of four lock gears, a pair of first lock gears 61 and a pair of second lock gears 62, a central cam 70, two substantially arc-shaped spring members 80, a substantially disk-shaped cam lever 90, and other members for locking and unlocking are disposed in this cavity C. In the following description, the left side of Figure 2 is one axial side, and the right side of Figure 2 is the other axial side.

[0017] The base plate 30 has a plurality of protrusions 30b formed on one axial side surface (hereinafter also referred to as the mounting surface 30a), and is attached to the lower bracket 11a by engaging each of these protrusions 30b with an engagement hole (not shown) of the lower bracket 11a. As shown in FIG. 4, the base plate 30 has four guide protrusions 31, 32, 31, 32 formed on the other axial side surface for guiding each of the lock gears 61, 62 in the radial direction. In the following description, as shown in FIG. 4, of the pair of guide surfaces for guiding the first lock gear 61, the guide surface of the guide protrusion 31 is referred to as the first guide surface 33a on one side, and the guide surface of the guide protrusion 32 is referred to as the first guide surface 33b on the other side. Also, of the pair of guide surfaces for guiding the second lock gear 62, the guide surface of the guide protrusion 32 is referred to as the second guide surface 34a on one side, and the guide surface of the guide protrusion 31 is referred to as the second guide surface 34b on the other side.

[0018] The base plate 30 is formed with an insertion hole 35 through which the shaft portion (not shown) of the center shaft 22 is inserted. A circular recess 36 is provided on the other axial side surface of the base plate 30 at a position inside the guide protrusions 31, 32 so as to be coaxial with the insertion hole 35. As shown in FIG. 2, the recess 36 is formed so that one axial side of the cam 70 fits into the recess 36 to be able to rotate relatively. The depth H of the recess 36 can be set to be equal to the allowable axial deviation between the cam 70 and the lock gears 61, 62.

[0019] Internal teeth 41 are formed around the entire inner peripheral surface of the gear plate 40. A plurality of protrusions 40a are formed on the back surface (the surface on the other axial side) of the gear plate 40, and the gear plate 40 is attached to the upper bracket 12a by engaging each of these protrusions 40a with an engaging hole (not shown) of the upper bracket 12a.

[0020] Furthermore, two arcuate stepped portions are arranged at 180° intervals on the inner peripheral surface of the gear plate 40, which are formed coaxially with the internal teeth 41. The arcuate stepped portions are intended to realize the above-mentioned lock-free state, and are formed so that the angular range in which a protrusion 63 (described later) of the first lock gear 61 abuts from the inner peripheral side corresponds to the above-mentioned free rotation range.

[0021] As shown in Figs. 3 and 4, external teeth 61a, 62a that can mesh with the internal teeth 41 of the gear plate 40 are formed on the outer periphery of both first lock gears 61 and both second lock gears 62. Each lock gear 61, 62 is assembled so as to be guided radially slidably using the guide surfaces 33a, 33b, 34a, 34b of the base plate 30. Specifically, both first lock gears 61 are guided by one first guide surface 33a of the guide protrusion 31 and a movable guide 37 (described later) that is guided by the other first guide surface 33b of the guide protrusion 32, and are supported so as to be slidable only in the radial direction. In addition, both second lock gears 62 are guided by one second guide surface 34a of the guide protrusion 32 and the other second guide surface 34b of the guide protrusion 31, and are supported so as to be slidable only in the radial direction.

[0022] In addition, each of the first lock gears 61 is provided with a projection 61b projecting toward the other axial side (gear plate side), and each of the second lock gears 62 is provided with a projection 62b projecting toward the other axial side. Both projections 61b and both projections 62b function to control the radial movement of each of the lock gears 61, 62 by being guided by a rotating cam lever 90 as described later. In addition, each of the first lock gears 61 is provided with a projection 63 on the outer side of the projection 61b, and both projections 63 are formed so as to maintain a state in which the meshing between the internal teeth 41 and the external teeth 61a is released by abutting against the arc-shaped step portion of the gear plate 40 from the inner circumferential side.

[0023] The movable guide 37 is formed in a wedge shape so that its width gradually narrows from one end to the other end, and is disposed between the first lock gear 61 and the other first guide surface 33b of the guide protrusion 32 so as to be able to slide. An engagement hole 37a for engaging one end of a spring member 80 is formed in each of the movable guides 37, and by engaging one end of the spring member 80 with the engagement hole 37a, the both movable guides 37 are biased inwardly of the base plate 30 by the spring member 80. As a result, the movable guide 37 is always in a state of being wedged between the first lock gear 61 and the other first guide surface 33b, and the first lock gear 61, the other first guide surface 33b, and the movable guide 37 are tightly fitted together (fitted together), eliminating any gaps between the respective members. Therefore, rattling in the front-rear direction of the seat back 12 is eliminated. The spring member 80 may be an example of a "biasing member."

[0024] A plate-shaped cam 70 having a through hole 71 formed therein for inserting the shaft portion of the center shaft 22 is rotatably disposed on the base plate 30, utilizing the recess 36. The cam 70 is formed so that cam surfaces 72 abut against the inner end faces 61c of both lock gears 61 and the inner end faces 62c of both lock gears 62 from the radially inner side, respectively, and causes the external teeth 61a, 62a of the lock gears 61, 62 to mesh with the internal teeth 41 of the gear plate 40 when the cam 70 rotates to a predetermined state about the shaft portion serving as the rotation shaft. The cam 70 also has two engagement holes 73 on its side with which the other end of the spring member 80 engages, and two cylindrical projections 74 projecting to the other axial side.

[0025] In particular, the cam 70 is formed so that the axial length T1 of the cam surface 72 is longer than the axial length T2 of the inner end faces 61c, 62c of the lock gears 61, 62. More specifically, the cam 70 is formed so that the axial length T1 of the cam surface 72 is equal to the sum of the axial length T2 of the inner end faces 61c, 62c and the depth H of the recess 36 of the base plate 30. For this reason, as shown in Fig. 6, when one axial side of the cam 70 enters so as to contact the bottom surface 36a of the recess 36, the other axial side of the cam surface 72 and the other axial side of the inner end faces 61c, 62c are flush with each other.

[0026] 5, the cam 70 is strongly biased in the lock rotation direction (clockwise in FIGS. 4 and 5) by engaging with the other ends of the two spring members 80. As a result, the cam 70 abuts against the inner end faces 61c, 62c of the lock gears 61, 62 at the cam surface 72, and the biasing forces in the lock rotation direction by the two spring members 80 strongly bias the lock gears 61, 62 radially outward.

[0027] The shaft portion of the center shaft 22 is inserted into the through hole 71 of the cam 70, and by rotating this center shaft 22, the cam 70 can be rotated in the unlock rotation direction (counterclockwise in Figures 4 and 5) against the biasing force of both spring members 80.

[0028] 5, the cam lever 90 is provided with a through hole 91 into which both protrusions 74 of the cam 70 are fitted, two cam holes 92, and two cam holes 93. The cam lever 90 is assembled to the cam 70 and the lock gears 61, 62 with both through holes 91 and both protrusions 74 fitted together, the protrusion 61b inserted into both cam holes 92, and the protrusion 62b inserted into both cam holes 93.

[0029] As a result, when the cam lever 90 rotates together with the cam 70 in the unlock rotation direction, the inner peripheral edge of the cam hole 92 abuts against the projections 61b of the first lock gear 61, and the inner peripheral edge of the cam hole 93 abuts against the projections 62b of both second lock gears 62. When the cam lever 90 rotates further in the unlock rotation direction, these projections 61b, 62b are urged radially inward by the inner peripheral edges of the cam holes 92, 93, causing the lock gears 61, 62 to move radially inward in unison. The cam lever 90 can be considered an example of a "release member".

[0030] In the reclining device 20 thus constructed, the lock gears 61, 62, the movable guide 37, the cam 70, etc. are disposed within the cavity C and assembled together into a base plate 30 and a gear plate 40, which are then ring-crimped to the side periphery by the cover bracket 50. This allows the base plate 30 and the gear plate 40 to be held so as to be rotatable relative to each other, while preventing relative movement in the axial direction.

[0031] 2 is completed by assembling the reclining operation lever 23 to the center shaft 22, the shaft portion of which is inserted into the through hole 71 of the cam 70. In the reclining device 20 configured in this manner, the seat cushion 11 and the seat back 12 are connected by the reclining device 20 so as to be able to tilt relative to each other by engaging each protrusion 30b of the base plate 30 with the engaging hole of the lower bracket 11a and by engaging each protrusion 40a of the gear plate 40 with the engaging hole of the upper bracket 12a.

[0032] Next, the unlocked and locked states of the reclining device 20 according to this embodiment configured as described above will be described below.

[0033] (Unlocked) First, the unlocked state of the reclining device 20 will be described. When an occupant unlocks the seat back 12 to adjust the inclination angle of the seat back 12, the occupant operates the reclining operation lever 23 to rotate the center shaft 22 in the unlock rotation direction. Then, the cam 70 rotates together with the center shaft 22 in the unlock rotation direction against the biasing forces of both spring members 80.

[0034] When the cam 70 rotates in the unlock rotation direction, the cam surface 72 of the cam 70 is released from contact with the inner end faces 61c, 62c of each of the lock gears 61, 62, and the biasing force of the cam 70 biasing each of the lock gears 61, 62 radially outward is released. This enables each of the lock gears 61, 62 to move radially inward, and the meshing between the internal teeth 41 of the gear plate 40 and the external teeth 61a, 62a of each of the lock gears 61, 62 becomes disengageable.

[0035] Then, as the cam lever 90 rotates in the unlock rotation direction together with the cam 70, the inner edges of the cam holes 92, 93 of the cam lever 90 come into contact with the protrusions 61b, 62b of each lock gear 61, 62, actively moving each lock gear 61, 62 radially inward, and disengaging the internal teeth 41 from the external teeth 61a, 62a.

[0036] As described above, when the meshing between the internal teeth 41 and the external teeth 61a, 62a is released, the gear plate 40 becomes free to rotate, and the round reclining unit 21 becomes unlocked. When the round reclining unit 21 becomes unlocked, the reclining device 20 becomes unlocked, and when the seat back 12 is tilted backward, the tilt angle of the seat back 12 becomes freely adjustable (see angle A in FIG. 1).

[0037] (Unlocked state) Next, the unlocked state of the reclining device 20 will be described. In the above-described unlocked state, when the seat back 12 is tilted forward, the base plate 30 and the gear plate 40 rotate relative to each other, and both first lock gears 61 move to positions where the protrusion 63 can abut against the arc-shaped step portion of the gear plate 40. In this state, when the reclining operation lever 23 is loosened, the cam 70 rotates in the lock rotation direction due to the biasing force of both spring members 80, and the rotation of the cam 70 biases each of the lock gears 61, 62 radially outward.

[0038] At this time, the projections 63 of both first lock gears 61 abut against the arc-shaped stepped portions of the gear plate 40, so that the meshing between the internal teeth 41 and the external teeth 61a, 62a is maintained. Therefore, while the projections 63 abut against the arc-shaped stepped portions of the gear plate 40, even if the seat back 12 is tilted forward so that the base plate 30 and the gear plate 40 rotate relatively, the unlocked state is maintained (see angle B in FIG. 1).

[0039] (Locked) Next, the locked state of the reclining device 20 will be described. When the occupant has finished adjusting the reclining angle of the seat back 12, the reclining operation lever 23 is loosened, and the cam 70 is rotated in the lock rotation direction by the biasing forces of both spring members 80.

[0040] The cam surfaces 72 of the rotating cam 70 come into contact with the inner end faces 61c, 62c of the lock gears 61, 62, respectively, thereby biasing the lock gears 61, 62 radially outward. As a result, the external teeth 61a, 62a of the lock gears 61, 62 move radially outward so as to mesh with the internal teeth 41 of the gear plate 40. Then, as the external teeth 61a, 62a of the lock gears 61, 62 mesh with the internal teeth 41 of the gear plate 40, the rotation of the gear plate 40 is restricted, and the reclining device 20 enters a locked state.

[0041] Next, the effect of providing the recess 36 in the base plate 30 will be described with reference to Figures 7(A) and (B). In Figures 7(A) and (B), the dashed-dotted rectangular area on the left side is an enlarged view of the dashed-dotted rectangular area on the right side.

[0042] Since the reclining device 20 is assembled into the vehicle seat 10 so that the axial direction is approximately horizontal, when the reclining device 20 repeatedly transitions between the locked state, the unlocked state, and the unlocked state as described above, each part in the cavity C moves within a range of allowable axial deviation. At that time, as can be seen from Figures 7(A) and (B), the cam 70 may also shift in the axial direction relative to the lock gears 61 and 62.

[0043] In the reclining device 20 of this embodiment, a circular recess 36 into which one axial side of the cam 70 fits is formed on the surface of the base plate 30 facing the lock gears 61, 62 and the cam 70, and the cam 70 is formed so that the axial length T1 of the cam surface 72 is longer than the axial length T2 of the inner end faces 61c, 62c of the lock gears 61, 62.

[0044] Therefore, in the locked state, when one axial side of the cam 70 is inserted so as to contact the bottom surface 36a of the recess 36 as shown in FIG. 7(A), the other axial side of the cam surface 72 abuts against the inner end surfaces 61c, 62c of the lock gears 61, 62. Even if the cam 70 is shifted to the other axial side relative to the lock gears 61, 62 as shown in FIG. 7(B), the one axial side of the cam surface 72 abuts against the inner end surfaces 61c, 62c of the lock gears 61, 62. That is, the contact area between the cam surface 72 and the inner end surfaces 61c, 62c does not change due to the axial shift between the cam 70 and the lock gears 61, 62. Therefore, even if the cam 70 is shifted in the axial direction relative to the lock gears 61, 62, the necessary contact area can be secured between the cam surface 72 of the cam 70 and the inner end surfaces 61c, 62c of the lock gears 61, 62.

[0045] In particular, the cam 70 is formed so that the axial length T1 of the cam surface 72 is equal to the sum of the axial length T2 of the inner end faces 61c, 62c and the depth H of the recess 36 (see FIG. 6). As a result, even when one axial side of the cam 70 enters so as to contact the bottom face 36a of the recess 36, the other axial side of the cam surface 72 and the other axial side of the inner end faces 61c, 62c are flush with each other, so that a necessary contact area can be secured between the cam surface 72 of the cam 70 and the inner end faces 61c, 62c of the lock gears 61, 62.

[0046] [Other embodiments] The present invention is not limited to the above-described embodiment, and may be embodied as follows, for example. (1) The recess 36 of the base plate 30 does not have to be formed in a circular shape, and may be formed in a shape that allows one axial side of the cam 70 to fit therein and rotate relatively.

[0047] (2) The recess 36 is not limited to being formed so that the sum of its depth H and the axial length T2 of the inner end faces 61c, 62c is equal to the axial length T1 of the cam surface 72. For example, depending on the environment in which the reclining device 20 is used, the recess 36 may be formed so that the sum of its depth H and the axial length T2 of the inner end faces 61c, 62c is smaller than the axial length T1 of the cam surface 72.

[0048] (3) The present invention is not limited to being applied to the reclining device 20 in which the base plate 30 is attached to the lower bracket 11a and the gear plate 40 is attached to the upper bracket 12a, but may also be applied to a reclining device in which the base plate is attached to the upper bracket 12a and the gear plate is attached to the lower bracket 11a. In this configuration, the upper bracket 12a and the seat back 12 may correspond to the "first member," and the lower bracket 11a and the seat cushion 11 may correspond to the "second member." [Explanation of symbols]

[0049] 10...Vehicle seat 11...Seat cushion (first member) 11a...Lower bracket (first member) 12...Seat back (second member) 12a...Upper bracket (second member) 20...Reclining device 30…Base plate 33a, 33b...First guide surface (guide surface) 34a, 34b...Second guide surface (guide surface) 36…Recess 36a…Bottom surface 40…Gear plate 41…Inner teeth 61…1st lock gear 61a…external teeth 61c…Inner end surface 62…Second lock gear 62a…Outer teeth 62c…Inner end surface 70…Cam 72…Cam surface 80...Spring member (biasing member) 90...Cam lever (release member)

Claims

1. A reclining device that adjusts a tilt angle between a first member and a second member that tilt relatively, comprising: A base plate attached to the first member; a gear plate attached to the second member and assembled to be rotatable relative to the base plate, the gear plate having internal teeth; a lock gear that is assembled so as to be guided radially slidably by utilizing a guide surface formed on the base plate, and has external teeth that can mesh with the internal teeth; a cam that, when rotated about a predetermined rotation axis, abuts against an inner end surface of the lock gear from the inside in the radial direction at a cam surface, thereby causing the external teeth to mesh with the internal teeth; a biasing member that biases the cam in a direction in which the external teeth mesh with the internal teeth; a release member capable of releasing the meshing between the external teeth and the internal teeth by rotating the cam against the biasing force of the biasing member; Equipped with a recess into which one axial side of the cam fits, is formed on a surface of the base plate facing the lock gear and the cam; The cam is formed so that the axial length of the cam surface is longer than the axial length of the inner end face of the lock gear.

2. 2. The reclining device according to claim 1, wherein the cam is formed so that the axial length of the cam surface is equal to the sum of the axial length of the inner end surface and the depth of the recess.

Images