Reclining device for vehicle seat

Abstract

A reclining device includes: a base plate; a tooth plate being rotatable and including a first depression, a second depression shaped annular, and an internal teeth formed in an inner peripheral surface of the first depression; three lock members including external teeth structured to engage with the internal teeth; a cam structured to move the lock members. Each of the lock members includes a first projection. The second depression includes first restriction parts structured to radially contact with the first projections and restrict movement of the lock members in an engagement direction. At least one of the lock members includes a second projection. The tooth plate includes a second restriction part structured to contact with the second projection at a position radially inside with respect to a position of contact between the first projection and the first restriction part.

Description

RECLINING DEVICE FOR VEHICLE SEAT

[0001] The present invention relates to improvement of a reclining device for a vehicle seat.

[0002] Reclining devices for vehicle seats with seat cushions serving as seats and seat backs serving as backrests are known to be designed to have a reclining range to allow stepwise adjustment of rearward inclination posture of the seat back and locking of the posture and a so-called free range not to lock the seat back. In a representative design, the reclining range is from a substantially upright posture to a most-rearward-inclined posture (i.e., a so-called full flat position) of a seat back, and the free range is from the upright posture to a most-forward-inclined posture of the seat back. A sum of the reclining range and the free range, i.e., a range from the most-forward-inclined posture to the most-rearward-inclined posture, is sometimes set to about 180 degrees.

[0003] In addition, there are various proposals for a reclining device including a disk-shaped unit that is a joint or a hinge for connection between a seat cushion and a seat back and serves for posture adjustment of the seat back.

[0004] For example, Patent Document 1 discloses a reclining device including a base member, a tooth member, and three lock members contained inside the base member and the tooth member. The reclining device is structured to: in a reclining range (i.e., a lock range), positively engage / separate external teeth of the three lock members with / from internal teeth of the tooth member, and thereby allow change of posture and locking of a seat back; and in a free range, restrict movement (or positions) of the lock members and maintain an unlocked state to prevent the external teeth of the lock members from engaging with the internal teeth of the tooth member, and thereby secure a free state.

[0005] Thus, it is general to configure a reclining device to include three or four lock members for improving lock strength by increasing a number of the lock members.

[0006] In case of employing three or more lock members, to secure a sufficient free range, Patent Document 1 discloses forming a projection (51) in only one of the lock members and forming a protrusion (27) in the tooth member (i.e., an upper arm) oppositely to the projection. The projection and the protrusion are structured to contact with each other, prevent the external teeth of the one lock member from engaging with the internal teeth of the tooth member, and retain the one lock member at an inner position. In this occasion, a cam stops rotation in a state in which a lock-side cam surface of the cam has pushed out the one lock member in a direction for lock. Thus, also the other two lock members including no projection are at positions to prevent engagement of the external teeth, i.e., positions to prevent radially outward movement of the external teeth.

[0007] However, there is a clearance in a direction of rotation of the cam, between a position at which the lock-side cam surfaces of the cam contact with the lock members and a position at which release-side cam surfaces of the cam contact with the lock members. Thus, each of the other two lock members including no projection is allowed to move in the radially outward direction (i.e., a direction for engagement with the internal teeth), more than the one lock member including the projection by a width of the clearance. This may allow the other two lock members to unintendedly move in the radially outward direction due to inertia, vibration, etc. of a vehicle, cause contact between tips of the internal teeth and the external teeth, and make a noise.

[0008] In view of this, the invention of Patent Document 1 is configured to position the other two lock members including no projection, upper with respect to a rotational center of the reclining device, and prevent the external teeth from moving in the direction for engagement with the internal teeth, with use of gravity.

[0009] However, this countermeasure retains the other two lock members at positions apart from the internal teeth, and may fail to be locked at an initial-stage lock position (i.e., a standing position) being an initial lock position in a lock range of the seat back, upon returning from a free range to the lock range, and undergo so-called tooth skipping.

[0010] Furthermore, the projection of the one lock member may collide with a side surface of the protrusion of the tooth member, upon operating the cam with an operational lever in a lock release direction and thereby moving the lock members in the radially inward direction to get apart from the internal teeth. In such structure of forming the projection in only the one lock member, side surfaces of the projection of the one lock member and the protrusion of the teeth member may be deformed due to collision therebetween, in particular in case of a vehicle seat greater in weight of the seat back and greater in bias force of a spring biasing the seat back to a forward inclination side.

[0011] In view of this, Patent Document 2 discloses an invention configured such that a projection of one lock member faces a first guide part over an entire free range, while projections of other lock members face second guide parts in a partial region of the free range adjacent to a lock range. This serves to distribute collision load even in case of collision of the projections of the lock members with side surfaces of the guide parts due to insufficiency in radially inward movement of the lock members, and thereby suppress deformation of side surfaces of the projections of the lock members and the guide parts due to the collision therebetween.

[0012] JP 2003-009978 AJP 2018-023583 A

[0013] However, even the invention of Patent Document 2 may undergo a problem of movement of the other lock members in a radially outward direction (i.e., a lock direction), in the free range in which the projections do not face the second guide parts. Thus, the other lock members have to be disposed apart from internal teeth because of the movement of the other lock members in the lock direction, similarly to the invention of Patent Document 1. This brings, similarly to the invention of Patent Document 1, a technical problem of so-called tooth skipping between the internal teeth and external teeth due to failure in locking at an initial-stage lock position (i.e., a standing position) being an initial lock position in the lock range.

[0014] Furthermore, the art of Patent Document 2 has another technical problem of instability in timing at which the projections of the first and second lock members depart from the guide parts and the external teeth engage with the internal teeth at the initial-stage lock position, because the projection of the first lock member and the projection of the second lock member are different from each other in radial position.

[0015] In view of the foregoing technical problems of the conventional reclining devices, it is desirable to provide a reclining device for vehicle seat structured to: prevent a noise due to contact between internal teeth of a tooth member and external teeth of lock members; stabilize timing of engagement between the internal teeth and the external teeth; reduce occurrence of tooth skipping at an initial-stage lock position upon return from a free range to a lock range of a seat back; and prevent projections of the lock members and restriction parts of the tooth member from colliding with each other in a circumferential direction and thereby deforming.

[0016] According to one aspect of the present invention, a reclining device for a vehicle seat includes: a base member fixed to a first one of a lower bracket of a seat cushion and an upper bracket of a seat back; a tooth member fixed to a second one of the lower bracket and the upper bracket, disposed to overlap with the base member, and structured to rotate relatively with respect to the base member; a first depression shaped circular, formed inside an outer periphery of the tooth member, and centered at a rotational center of the tooth member; internal teeth formed in an inward peripheral surface of the first depression; lock members disposed between the base member and the tooth member and arranged in a circumferential direction, wherein each of the lock members includes external teeth movable in a radial direction so as to engage with the internal teeth at a lock position and release the engagement at an unlock position; a cam disposed radially inside with respect to the lock members and structured to cause the lock members to move between the lock positions and the unlock positions; and a bias member biasing the lock members via the cam in a lock direction that is a direction for engagement of the internal teeth and the external teeth. The tooth member includes a second depression shaped annular, formed radially inside the first depression, and centered at the rotational center of the tooth member. Each of the lock members includes a first projection that projects toward the second depression and is structured to face an outer side inward peripheral surface of the second depression in the radial direction. The second depression includes first allowance parts and first restriction parts. The first allowance parts are structured to respectively face the first projections via gaps and allow the lock members to move to the lock positions, in a lock range that is set in a rearward inclination side from an initial-stage lock position of the seat back with respect to the seat cushion. The first restriction parts are structured to be positioned radially inside with respect to the first allowance parts and respectively contact with the first projections in the radial direction and restrict movement of the first projections in the engagement direction, in a first angular range that is set in a forward inclination side from the initial-stage lock position of the seat back with respect to the seat cushion. At least one of the lock members includes a second projection that is positioned radially inside with respect to the first projection and projects to an inside of the second depression. The tooth member includes a second restriction part. The second restriction part is structured to contact with the second projection of the one of the lock members at a position radially inside with respect to a position of contact between the first projection and the first restriction part, in a second angular range that is set in a further forward inclination side from a position at least partially overlapping with the first angular range set in the forward inclination side from the initial-stage lock position of the seat back.

[0017] The invention claimed in claim 1 of the present application serves to: prevent a noise due to contact between internal teeth of a tooth member and external teeth of lock members; stabilize timing of engagement between the internal teeth and the external teeth; reduce occurrence of tooth skipping at an initial-stage lock position upon return from a free range to a lock range of a seat back; and prevent projections of the lock members and restriction parts of the tooth member from colliding with each other in a circumferential direction and thereby deforming.

[0018] Fig. 1 is a side view of a reclining device for vehicle seat according a first embodiment of the present invention.Fig. 2 is an oblique exploded view of only a reclining section of the reclining device for vehicle seat shown in FIG. 1.Fig. 3(A) is a front view showing how a base plate and spiral springs are arranged. Fig. 3(B) is a sectional view along a line A-A in Fig. 3(A).Fig. 4(A) is a front view showing how the base plate, the spiral springs, lock members, and a cam are arranged. Fig. 4(B) is a sectional view along a line B-B in Fig. 4(A).Fig. 5 is an oblique view of a tooth plate in Fig. 2 when viewed from an inner side.Fig. 6 is a front view of the tooth plate in Fig. 2 when viewed from the inner side.Fig. 7(A) is a transparent view showing how respective members in Fig. 2 are arranged when viewed from a tooth plate side. Fig. 7(B) is a sectional view along a line C-C in Fig. 7(A).Fig. 8 is an operation illustrative view in a state in which the reclining section is at an initial-stage lock position of Fig. 1, when viewed transparently from the tooth plate side.Fig. 9 is an operation illustrative view unfoldingly showing relations between first restriction parts and first allowance parts of the tooth plate and respective first projections, and correspondence relations between second restriction parts and a second allowance part and respective second projections.Fig. 10 is an operation illustrative view in a state after having shifted from a lock range to a first angular range, when viewed transparently from the tooth plate side in a free range of a seat back.Fig. 11 is an operation illustrative view at a most-forward-inclined position in a second angular range side of the first angular range, when viewed transparently from the tooth plate side in the free range of the seat back.Fig. 12 is a front view showing how respective members of a reclining device are arranged, according to a second embodiment of the present invention.Fig. 13 is an operation illustrative view unfoldingly showing, according to the second embodiment, relations between the first restriction parts and the first allowance parts of the tooth plate and the respective first projections, and correspondence relations between the second restriction parts and the second allowance part and the second projection.Fig. 14 is a sectional view of a reclining device according to a third embodiment of the present invention.Fig. 15 is a sectional view of a reclining device according to a fourth embodiment of the present invention.

[0019] The following describes embodiments of a reclining device for a vehicle seat according to the present invention.

[0020] Fig. 1 and the following drawings specifically show the embodiments for implementation of a reclining device for a vehicle seat according to the present invention. In particular, Fig. 1 is a schematic side view of the whole. Fig. 2 is an oblique exploded view of a reclining section 5.

[0021] As shown in Fig. 1, the reclining device 1 includes a vehicle seat 2 composed of a seat cushion 3 and a seat back 4, and includes the reclining section 5 as a major section for adjusting a posture of the seat back 4 that is structured to stand and lie. The reclining section 5 has a flat disc shape, is disposed in a junction of the seat cushion 3 and the seat back 4, and serves as a joint or a hinge to perform a reclining function.

[0022] In detail, as shown in Fig. 1, the reclining section 5 is formed as a unit beforehand, and is disposed in a junction of a lower bracket 6 and an upper bracket 7. The lower bracket 6 is fixed to a seat cushion frame not shown that is a frame of the seat cushion 3. The upper bracket 7 is fixed to a seat back frame not shown that is a frame of the seat back 4. From the reclining section 5, an operation lever 8 projects. The operation lever 8 is an operation member for reclining operation. In addition, the seat back 4 always receives bias force in a forward inclination direction exerted by a spring not shown.

[0023] As clearly shown in Fig. 1, an initial-stage lock position P1 is a standard posture position of the seat back 4 inclined rearward, i.e., a reference position in design of the seat back 4. A standing position P2 is a position at which the seat back 4 is inclined forward slightly with respect to the initial-stage lock position P1 and stands substantially upright. In this case, as mentioned above, it is allowed to arbitrarily adjust the rearward inclination posture position of the seat back 4 and lock the posture position, within a range from the initial-stage lock position P1 to a most-rearward-inclined position P3 (i.e., a so-called full flat position) of the seat back 4. This range is a lock range (or a lock region) R1. A first angular range R2 is an angular range from the initial-stage lock position P1 to the standing position P2. A second angular range R3 is an angular range from the initial-stage lock position P1 to a most-forward-inclined position P4 of the seat back 4, which includes the first angular range R2. In the second angular range R3 from the initial-stage lock position P1, the seat back 4 is not locked but is in an unlocked state, and can freely incline forward and rearward (i.e., freely rotate). Thus, the second angular range R3 corresponds to a free range. In case of inclining the seat back 4 rearward from the second angular range R3, the seat back 4 is locked and bound in posture for the first time at the initial-stage lock position P1.

[0024] As shown in Fig. 2, the reclining section 5 includes a base plate 9, a tooth plate 10, a retention ring 11, three lock members 12A and 12B and 12C, a cam 14, and three spiral springs 13. The base plate 9 is a base member having a shape of a shallow dish disc shape. The tooth plate 10 is a tooth member having a shape of a shallow dish disc shape, and is disposed to face and overlap with the base plate 9. The retention ring 11 bounds and retains the base plate 9 and the tooth plate 10 such that the base plate 9 and the tooth plate 10 are allowed to rotate relatively with each other. Each of the three lock members 12A, 12B, and 12C has a shaped of a sector gear, and is disposed between the base plate 9 and the tooth plate 10. The cam 14 has a triangular shape, and is disposed in an inner circumferential side with respect to the three lock members 12A, 12B, and 12C. The three spiral springs 13 are bias members biasing the cam 14 in a direction to cause the cam 14 to press the three lock members 12A, 12B, and 12C outwardly. In addition, as described below, the cam 14 is connected to a rotational shaft 8a of the operation lever 8 shown in Fig. 1 via serration connection.

[0025] Fig. 3(A) and Fig. 3(B) are respectively a front view and a sectional view showing how the base plate 9 and the spiral springs 13 are arranged.

[0026] The base plate 9 is formed by molding a disc-shaped material uniform in thickness into a shallow dish shape by pressing in a thickness direction by a method such as high precision press molding. The base plate 9 includes an inner bottom surface including spring-containing depressions 15. The spring-containing depressions 15 are depressed to a lower level, and are formed at trisection positions in a circumferential direction. Each of the spring-containing depressions 15 includes at its substantially center a spring-receiving projection 16 that is formed by so-called half blanking. Thus, each of the spring-containing depressions 15 contains one of the spiral springs 13 such that an inner circumferential side end 13a of the one of the spiral springs 13 is locked on the spring-receiving projection 16.

[0027] The inner bottom surface of the base plate 9 further includes shafts 17 and guide embossed parts 18 so as not to interfere with the spring-containing depressions 15. The shafts 17 are arranged at trisection positions in the circumferential direction, while the guide embossed parts 18 are arranged at another trisection positions different from the shafts 17 in phase. The shafts 17 and the guide embossed parts 18 project in a direction opposite to the spring-containing depressions 15. The shafts 17 respectively support the lock members 12A to 12C swingably. The guide embossed parts 18 respectively guide swing of the lock members 12A to 12C.

[0028] Fig. 4(A) and Fig. 4(B) are a front view and a sectional view showing how the base plate 9 contains the spiral springs 13, the lock members 12A to 12C, and the cam 14.

[0029] The three lock members 12A to 12C are contained at circumferential positions same with the spiral springs 13 contained in the spring-containing depressions 15, so as to partially overlap with the spiral springs 13. Each of the lock members 12A to 12C includes a receiving depression 19 formed by cutting, and engages with a corresponding one of the shafts 17, using the receiving depression 19 as a bearing. Furthermore, each of the guide embossed parts 18 guides an outer periphery of a corresponding one of the lock members 12A to 12C, around a corresponding one of the shafts 17. These configurations allow the lock members 12A to 12C arranged at circumferential trisection positions, to swing. This allows external teeth 20 of the lock members 12A to 12C to be supported swingably in a radial direction of the base plate 9, wherein centers of the swing are the shafts 17. Each of the shafts 17 and the receiving depressions 19, which are structured to engage with each other, includes both ends in a circumferential direction of the base plate 9 each of which has a cylindrical surface to allow relative rotation, in order to achieve functions of the shafts 17 and the receiving depressions 19.

[0030] Each of the lock members 12A to 12C has a so-called sector shape having an inner arc surface (i.e., the receiving depression 19) and an outer arc surface. The sector includes a first side surface including the external teeth 20. Furthermore, the lock members 12A to 12C respectively include first projections 21a to 21c formed by so-called half blanking. In detail, the lock member 12A includes the first projection 21a, the lock member 12B includes the first projection 21b, and the lock member 12C includes the first projection 21c. Each of the first projections 21a to 21c projects from a surface of the sector facing the tooth plate 10, in a vicinity of the first side surface of the sector. In the circumferential direction around a rotational center of the tooth plate 10, each of the first projections 21a to 21c is positioned middle with respect to the external teeth 20. In the radial direction, each of the first projections 21a to 21c is positioned inside with respect to the external teeth 20.

[0031] The two lock members 12A and 12B out of the three lock members 12A to 12C respectively include second projections 22a and 22b formed by half blanking. Each of the second projections 22a and 22b is shaped to have a rectangular cross section, projects in the direction same with the first projections 21a and 21b, and is positioned in a vicinity of a second side surface of the sector opposite to the external teeth 20. In other words, each of the second projections 22a and 22b is positioned oppositely to a corresponding one of the first projections 21a and 21b across the receiving depression 19. In the radial direction, each of the second projections 22a and 22b is positioned inside with respect to a corresponding one of the first projections 21a and 21b when viewed from the rotational center of the tooth plate 10.

[0032] As shown in Fig. 2 and Fig. 4, the cam 14 is disposed at a center of arrangement of the three lock members 12A to 12C so as to face the outer arc surfaces of the sectors of the three lock members 12A to 12C. Each of the lock members 12A to 12C includes a cam surface 23 (including a locked cam surface 23a and a released cam surface 23b) in the outer arc surface of the sector. Each of the cam surfaces 23 has a predetermined profile with a depression at a middle of the outer arc surface of the sector, and serves as a driven side. The cam 14 includes cam surfaces 24 at three apexes. Each of the cam surfaces 24 has a predetermined profile to engage with a corresponding one of the cam surfaces 23, includes a locking cam surface 24a and a releasing cam surface 24b, and serves as a driving side.

[0033] Thus, the depressions of the cam surfaces 23 as the driven side of the lock members 12A to 12C accept the cam surfaces 24 as the driving side of the cam 14.

[0034] The cam 14 includes internal serrations 14a at a center thereof, while the rotational shaft 8a of the operation lever 8 includes external serrations 8b. These internal and external serrations are coupled with each other, and thereby connect the operation lever 8 to the cam 14 integrally rotatably.

[0035] The cam 14 further includes spring-receiving protrusions 14b at three points adjacent to inner sides of the cam surfaces 24. The spring-receiving protrusions 14b are formed by so-called half blanking, and project toward the base plate 9. Then, each of outer circumferential side ends 13b of the spiral springs 13 is locked on a corresponding one of the spring-receiving protrusions 14b of the cam 14. This causes the spiral springs 13 to exert spring force in a clockwise direction of the cam 14 in Fig. 4, and consequently causes the cam 14 to bias the external teeth 20 of the lock members 12A to 12C outwardly in the radial direction.

[0036] As shown in Fig. 4, each adjacent pair out of the guide embossed parts 18, 18, and 18 interpose a corresponding one of the lock members 12A to 12C therebetween. Each of the lock members 12A to 12C is swingably supported from both sides via the outer arc surface of the sector, by arc guide surfaces 18a and 18b of the guide embossed parts 18. Accordingly, the lock members 12A to 12C structured to swing about the shafts 17 as fulcrums are also guided via outer peripheries thereof by the guide embossed parts 18. This allows the lock members 12A to 12C to move smoothly.

[0037] Fig. 5 is an oblique view of the tooth plate in Fig. 2 when viewed from the inner side. Fig. 6 is a front view of the tooth plate in Fig. 2 when viewed from the inner side.

[0038] Similarly to the base plate 9, the tooth plate 10 is formed by molding a disc-shaped material uniform in thickness into a shallow dish shape by pressing in a thickness direction, and includes a first depression 26. As shown in Fig. 5 and Fig. 6, the first depression 26 includes an inner peripheral wall surface including an internal teeth 25 over an entire circumference thereof. The tooth plate 10 further includes a second depression 27 formed adjacently to an inner side of the internal teeth 25 in an inner bottom surface of the tooth plate 10. The second depression 27 has an annular shape, is at a further lower level in an axial direction, and is concentric with the internal teeth 25.

[0039] As shown in Fig. 5 and Fig. 6, the second depression 27 includes an outer circumferential wall surface 27a, three first allowance parts 28, and three first restriction parts 29. The outer circumferential wall surface 27a is an outer side inward peripheral surface of the second depression 27 formed in an outer circumferential side of the second depression 27, and has an annular shape. The three first allowance parts 28 are formed in the outer circumferential wall surface 27a. The three first restriction parts 29 are formed between the first allowance parts 28 in the inward peripheral surface of the second depression 27, are arranged at positions of approximately 120° intervals in the circumferential direction, and project inwardly in the radial direction. The three first restriction parts 29 are positioned to respectively face the first projections 21a to 21c of the three lock members 12A to 12C in the radial direction with respect to the rotational center of the tooth plate 10, wherein the three lock members 12A to 12C project to an interior of the second depression 27, and outward surfaces of the three lock members 12A to 12C are allowed to contact with inner surfaces 29a of the first restriction parts 29. The first allowance parts 28 of the second depression 27 are positioned to respectively face the first projections 21a to 21c via gaps in the radial direction and be in noncontact with the first projections 21a to 21c, in the lock range. The second depression 27 further includes three notched depressions 30 at substantially middles of the first allowance parts 28 in the circumferential direction. The three notched depressions 30 extend outwardly in the radial direction. At least one of the three notched depressions 30 is narrower in circumferential width than the other two, and is used for circumferential positioning upon installation of the tooth plate 10.

[0040] As shown in Fig. 5 and Fig. 6, the second depression 27 includes an inner circumferential wall surface 27b positioned inside in the radial direction in comparison with the outer circumferential wall surface 27a. The inner circumferential wall surface 27b is an inner side outward peripheral surface of the second depression 27, has an annular shape, and includes two second restriction parts 31 and 32 and a second allowance part 33. The two second restriction parts 31 and 32 and the second allowance part 33 are arc-shaped, are formed continuously, and are different from each other in outer radius, wherein the second restriction part 32 is greater in radius than the second restriction part 31. The two second restriction parts 31 and 32 and the second allowance part 33 are arranged in series in the circumferential direction, each of which occupies an angular range of approximately 120°. The second allowance part 33 is less in outer radius than both of the two second restriction parts 31 and 32 such that the second projection 22a of the lock member 12A faces the second allowance part 33 via a gap in the radial direction and does not contact with the second allowance part 33.

[0041] In the lock range R1 in which the second projection 22a of the lock member 12A faces the second allowance part 33, the second projection 22b of the lock member 12B is positioned to face the less-radius second restriction part 31 via a gap in the radial direction and be in noncontact with the second restriction part 31. Thus, the second projection 22a of the lock member 12A is positioned inside in the radial direction in comparison with the second projection 22b of the lock member 12B. In addition, three steps 34, 35, and 36 are formed between the two second restriction parts 31 and 32 and the second allowance part 33.

[0042] In a state of the seat back 4 in the first angular range R2, the first projections 21a, 21b, and 21c of the three lock members 12A, 12b, and 12C are allowed to ride on the inner surfaces 29a of the first restriction parts 29. This prevents the external teeth 20 of the three lock members 12A, 12b, and 12C from engaging with the internal teeth 25 of the tooth plate 10. In a state of the seat back 4 in the second angular range R3, the second projections 22a and 22b of the two lock members 12A and 12B are allowed to ride on the inner side outward peripheral surfaces of the second restriction parts 31 and 32. This prevents the external teeth 20 of the two lock members 12A and 12b from engaging with the internal teeth 25. In this case, the external teeth 20 of the other lock member 12C fail to engage with the internal teeth 25 because the two lock members 12A and 12b stop rotation of the cam 14 having been biased in the lock direction.

[0043] Fig. 7(A) is a transparent view showing how respective components in Fig. 2 are arranged when viewed from the tooth plate side. Fig. 7(B) is a sectional view along a line C-C shown in Fig. 7(A).

[0044] As shown in Fig. 7(A) and 7(A), the first projections 21a to 21c projecting from the lock members 12A to 12C are accepted inside the second depression 27 of the tooth plate 10 when the tooth plate 10 and the base plate 9 are face to face with each other. Also the second projections 22a and 22b projecting from the two lock members 12A and 12B are accepted inside the second depression 27.

[0045] From the state of the tooth plate 10 face to face with the base plate 9 containing the spiral springs 13 and the three lock members 12A to 12C and the cam 14 as shown in Fig. 2, a retention ring 11 shown in Fig. 2 is plastically processed by a method such as roll forming or curling. This prevents the base plate 9 and the tooth plate 10 from separating from each other in the axial direction, while combining the base plate 9 and the tooth plate 10 concentrically with each other and relatively rotatably with respect to each other.

[0046] The cam 14 receives spring force from the spiral springs 13, and presses the three lock members 12A to 12C outwardly in the radial direction. This causes the external teeth 20 of the lock members 12A to 12C to engage with the internal teeth 25 of the tooth plate 10, and allows the locking. Thus, the three spiral springs 13 serve as bias members biasing the three lock members 12A to 12C in the lock direction to engage the external teeth 20 with the internal teeth 25.

[0047] As shown in Fig. 7(A), the less radius one and the greater radius one of the second restriction parts 31 and 32 formed in the inner circumferential wall surface 27b of the second depression 27 of the tooth plate 10 are different from each other in radius from the rotational center of the tooth plate 10. In correspondence to this, the second projection 22a of the first lock member 12A and the second projection 22b of the second lock member 12B are different from each other in radial position. Specifically, the second projection 22a of the first lock member 12A has a radial length L from the rotational center P of the tooth plate 10 which is longer than a radial length L1 of the second projection 22b of the second lock member 12B from the rotational center P.

[0048] Fig. 8 is an operation illustrative view in a state in which the reclining section is at the initial-stage lock position P1 of Fig. 1, when viewed transparently from the tooth plate side.

[0049] In the state of the seat back 4 in the initial-stage lock position P1 of Fig. 1, as shown in Fig. 8, each of the first projections 21a to 21c is positioned inside the second depression 27 and positioned adjacently to a circumferential front end of a corresponding one of the first allowance parts 28. The first projections 21a to 21c having been positioned at the first allowance parts 28 are allowed to ride on the inner surfaces 29a of the first restriction parts 29 as shown in Fig. 7(A), in response to rotational operation of the cam 14 to release the locking, move the lock members 12A to 12C inwardly to lock release positions (i.e., unlock positions), and allow the seat back 4 to rotate to a forward inclination side.

[0050] Furthermore, in the state of the initial-stage lock position P1, as shown in Fig. 8, the second projections 22a and 22b are respectively close to a first step 34 between the less-radius second restriction part 31 and the second allowance part 33 and a second step 35 between the less-radius second restriction part 31 and the greater-radius second restriction part 32. In response to rotational operation of the cam 14 and shift to the lock release positions, the second projections 22a and 22b are allowed to get over the first step 34 and the second step 35 as shown in Fig. 7(A).

[0051] The above exemplifies a case of welding the base plate 9 of the reclining section 5 to the lower bracket 6 and welding the tooth plate 10 of the reclining section 5 to the upper bracket 7. However, the base plate 9 and the tooth plate 10 may be exchanged with each other in relative positional relation with respect to the lower bracket 6 and the upper bracket 7.

[0052] <Effects of Reclining Device for Vehicle Seat of Present Embodiment> The following describes effects of the reclining section 5 configured as above, with reference to Fig. 8, 9, and 10 to 12. Fig. 9 is an operation illustrative view unfoldingly showing relations between the first restriction parts and the first allowance parts of the tooth plate and the respective first projections, and correspondence relations between the second restriction parts and the second allowance part and the respective second projections. Fig. 10 is an operation illustrative view of the seat back in the free range, which shows a state at a position after having shifted from the initial-stage lock position P1 to the first angular range R2. Fig. 11 is an operation illustrative view of the seat back in the free range, which shows a state at a position after having shifted from the second angular range R3 (i.e., the free range) to a position overlapping with the first angular range R2.

[0053] Fig. 8 shows the state in which the reclining section 5 is at the initial-stage lock position P1 shown in Fig. 1, which illustrates that the base plate 9 fixed to the lower bracket 6 serves as a fixed side, while the tooth plate 10 fixed to the upper bracket 7 serves as a movable side. The cam surfaces 24 of the driving side (i.e., the locking cam surfaces 24a) of the cam 14 are in contact with the locked cam surface 23a of the cam surfaces 23 of the lock members 12A to 12C, wherein each of the locked cam surface 23a is in a side of the external teeth 20 with respect to the shaft 17 serving as the fulcrum of swing. Each of the first projections 21a to 21c faces the outer side inward peripheral surface of the second depression 27 of the tooth plate 10, and faces a corresponding one of the first allowance parts 28 via a gap. In this state, each of the first projections 21a to 21c faces a first side surface 29c of the first restriction part 29 via a slight gap in the circumferential direction. Each of the second projections 22a and 22b faces an end surface of a corresponding one of the first step 34 and the second step 35 via a slight gap in the circumferential direction, and faces a corresponding one of the less-radius second restriction part 32 and the second allowance part 33 via a gap in the radial direction.

[0054] Thus, each of the lock members 12A to 12C swings outwardly in the radial direction around the shaft 17 as the fulcrum, and thereby the external teeth 20 engage with the tooth plate 10.

[0055] In response to operation of the operation lever 8 to rotate the cam 14 in the right direction from the state of Fig. 8 to the state of Fig. 10(a), the releasing cam surfaces 24b of the cam 14 press the released cam surfaces 23b of the lock members 12A to 12C. This causes the lock members 12A to 12C to swing inwardly about the shaft 17 as the fulcrum, and releases engagement between the external teeth 20 and the internal teeth 25 of the tooth plate 10. In this occasion, if the lock members 12A to 12C are less in inward retraction in the radial direction than a distance h1 shown in Fig. 9, the first projections 21a to 21c collide with the first side surfaces 29c of the first restriction parts 29 and stop at the standing position P2 of the seat back 4. The lock members 12A to 12C are structured such that all of the first projections 21a to 21c collide with the first side surfaces 29c of the first restriction parts 29 substantially simultaneously. This serves to distribute collision load, and thereby suppress compression deformation of the first projections 21a to 21c and the first restriction parts 29.

[0056] Furthermore in this occasion, as shown in Fig. 9, the lock members 12A and 12B are structured such that positions with respect to the first step 34 and the second step 35 formed between the second restriction parts 31 and 32 and the second allowance part 33 are shifted with respect to steps formed between the first restriction parts 29 and the first allowance parts 28, by a distance t1 in a direction to the second angular range R3 in the rotational direction. This prevents second projections 22a and 22b from colliding with the end surfaces of the first step 34 and the second step 35 of the second restriction parts 31 and 32.

[0057] In other words, omission of the distance t1 may allow the second projections 22a and 22b to collide with the end surfaces of the first step 34 and the second step 35 due to dispersion in distance. The present embodiment employs the distance t1 and thereby avoids the collision.

[0058] As described above, the lock members 12A to 12C are greater in inward retraction in the radial direction than the distance h1. This allows the seat back 4 to move to the second angular range R3 that is in the forward inclination side with respect to the initial-stage lock position P1.

[0059] As shown in Fig. 9, the first projections 21a to 21c and the second projections 22a and 22b when the external teeth 20 of the lock members 12A to 12C is in engagement with the internal teeth 25 are positioned such that a distance h3 required for riding-on of the second projections 22a and 22b onto outer surfaces of the second restriction parts 31 and 32 is greater in radially inward retraction of the lock members 12A to 12C than the distance h1 required for riding-on of the first projections 21a to 21c onto the inner surfaces 29a, by a distance h2. Thus, in case that the radially inward retractions of the lock members 12A to 12C are greater than the distance h1 and less than the distance h3, the second projection 22a and 22b may collide with the end surfaces of the steps 34 and 35.

[0060] However, the steps 34 and 35 are respectively continuous to slopes 37 and 38 structured to allow the second projections 22a and 22b to escape (i.e., move) inwardly in the radial direction. This prevents the second projections 22a and 22b from colliding with the end surfaces of the steps 34 and 35.

[0061] Each of the steps 34 and 35 of the second restriction parts 31 and 32 includes a corner formed lower than the distance h1 required for riding-on onto the first restriction parts 29, by a distance h4. This prevents the second projections 22a and 22b from colliding with the end surfaces of the steps 34 and 35 of the second restriction parts 31 and 32. In addition, in the state of Fig. 10(a), each of the second projections 22a and 22b faces a corresponding one of the second restriction parts 31 and 32 via a minute gap in the radial direction as shown in Fig. 10(b), while each of the first projections 21a to 21c is in contact with a corresponding one of the inner surfaces 29a of the first restriction parts 29 as shown in Fig. 10(c).

[0062] Next, in a state of the seat back 4 at a most forward inclined position within the lock range R1 overlapping with the second angular range R3, as shown in Fig. 11(a) to 11(c), the second projections 22a and 22b are respectively in contact with the second restriction parts 31 and 32, while each of the first projections 21a to 21c of the lock members 12A to 12C is positioned radially inwardly by the distance h2 with respect to a corresponding one of the inner surfaces 29a of the first restriction parts 29, and has a gap with the inner surface 29a so as not to contact with it. In Fig. 10 and Fig. 11, each of broken lines adjacent to the second restriction parts 31 and 32 represents a case of forming the second restriction parts 31 and 32 at positions same with the position of the distance h1 that are the riding-on positions onto the first restriction parts 29. In Fig. 9, the distance h3 is a distance of bringing-up of the second projections 22a and 22b by the second restriction parts 31 and 32, which satisfies a relation of h3 - h1 = h2.

[0063] The cam 14 is rotationally biased by the bias force of the spiral springs 13 in the direction to push out the lock members 12A to 12C outwardly in the radial direction, although the lock members 12A and 12B are prevented from swinging outwardly in the radial direction because of contact between the second projections 22a and 22b and the second restriction parts 31 and 32. This results in that rotation of the cam 14 is stopped in a state in which the cam surfaces 24 (i.e., the locking cam surfaces 24a) of the cam 14 press the locked cam surfaces 23a of the first and second lock members 12A and 12B. The third lock member 12C with no second projections 22a and 22b is maintained at the lock release state due to stopping of rotation of the cam 14. The third lock member 12C is allowed to move in the lock direction until the released cam surface 23b thereof contacts with the releasing cam surface 24b of the cam 14. Thus, the third lock member 12C may move in the lock direction up to a contact position with the releasing cam surface 24b of the cam 14, due to vibration, acceleration, etc.

[0064] However, as shown in Fig. 9, the third lock member 12C (i.e., the first projection 21c) is positioned inwardly by the distance h2 with respect to the contact position with the inner surface 29a of the first restriction part 29. This prevents the external teeth 20 of the third lock member 12C from contacting with the internal teeth 25 and making a noise. Furthermore, the above configuration prevents the first projection 21c of the third lock member 12C from colliding with a second side surface 29d of the first restriction part 29, upon rearward inclination toward the first angular range R2 in the second angular range R3.

[0065] Thus, upon inclining the seat back 4 rearward from the free range R3 to the lock range R1 as shown in Fig. 1, the second projections 22a and 22b move in contact with upper surfaces of the second restriction parts 31 and 32 as shown in Fig. 11, while moving outwardly in the radial direction along the slopes 37 and 38. At a middle position in the first angular range R2 in the free range R3, as shown in Fig. 9, the first projections 21a to 21c of the lock members 12A to 12C contact with the inner surfaces 29a of the first restriction parts 29. In Fig. 4, a range R4 represents a range within which the second projections 22a and 22b are in contact with the second restriction parts 31 and 32 and the slopes 37 and 38. The second projections 22a and 22b depart from them at the middle position of the first angular range.

[0066] In response to rotation of the seat back 4 from the middle position of the first angular range R2 to an end of the first angular range R2 adjacent to the lock range R1, the first projections 21a to 21c move in contact with the first restriction parts 29, while the second projections 22a and 22b gradually increase in distance from the slopes 37 and 38.

[0067] In response to rotation of the seat back 4 from the first angular range R2 to the lock range R1, the first projections 21a to 21c depart from the first restriction parts 29, the cam 14 rotates in the lock direction and pushes out the lock members 12A to 12C outwardly in the radial direction, and the external teeth 20 of the lock members 12A to 12C engage with the internal teeth 25 of the tooth plate 10 at the initial-stage lock position P1 and are locked.

[0068] In this occasion, all of the first projections 21a to 21c of the lock members 12A to 12C depart from the first restriction parts 29 at a same timing. Upon departure of the first projections 21a to 21c from the first restriction parts 29, it is unnecessary to consider the distance h2. This allows reduction in distance to the first allowance parts 28, and serves to prevent tooth skipping between the external teeth 20 and the internal teeth 25.

[0069] The free range (i.e., the second angular range R3) including the first angular range R2 of the seat back 4 is a range from a position at which the first projection 21a of the lock member 12A gets on the inner surface 29a of the first restriction part 29, to a position at which the second projection 22a of the lock member 12A collides with the end surface of the second step 35 of the second restriction part 32.

[0070] Thus, the reclining device for vehicle seat according to the present embodiment is configured to restrict radially outward movement of the lock members 12A to 12C in the second angular range R3 including the first angular range R2 where the seat back 4 is inclined forward. This serves to prevent a dragging noise caused due to contact between the external teeth 20 and the internal teeth 25.

[0071] Upon returning the seat back 4 from the free range R3 to the lock range R1 and locking the seat back 4, the present embodiment serves to stabilize timing of engagement between the external teeth 20 of the lock members 12A to 12C and the internal teeth 25 of the tooth plate 10, while reducing distances between the external teeth 20 and the internal teeth 25 in the state of the first projections 21a to 21c in contact with the first restriction parts 29. This reduces occurrence of tooth skipping at the initial-stage lock position P1 upon return from the free range R3 to the lock range R1. <Second Embodiment> Fig. 12 and Fig. 13 show a reclining device for vehicle seat according to a second embodiment of the present invention. Basic configurations of the second embodiment are same with those of the first embodiment, where the same elements are represented by the same reference numerals. The second embodiment eliminates one of the second projections and one of the second restriction parts. Fig. 12 is a front view when viewed from the tooth plate side. Fig. 13 is an operation illustrative view unfoldingly showing relations between the first restriction parts and the first allowance parts of the tooth plate and the respective first projections, and correspondence relations between the second restriction part and the second allowance parts and the second projection, according to the second embodiment.

[0072] Specifically, out of the first to third lock members 12A to 12C, the second projection 22b of the second lock member 12B is eliminated, and only the second projection 22a of the first lock member 12A is maintained, as shown in Fig. 12 and Fig. 13. Out of the two second restriction parts 31 and 32 formed in the inner circumferential wall surface 27b of the second depression 27, the second restriction part 32 corresponding to the second projection 22b is eliminated, and only the second restriction part 31 structured to face the second projection 22a in the second angular range is maintained.

[0073] While the second projection 22a is same in position with the first embodiment, the second restriction part 31 includes the slope 37 in a first end in the circumferential direction thereof and a slope 39 in a second end in the circumferential direction thereof. Thus, the second projection 22a and the second restriction part 31 are formed such that, in case of reverse rotation of the tooth plate 10 with respect to the base plate 9, the first projections 21a to 21c and the first restriction parts 29 are arranged at same positions, similarly to normal rotation.

[0074] Although the second embodiment is same with the first embodiment in basic actions and effects, the configuration of eliminating the second projection 22b and the second restriction part 32 allows the tooth plate 10 to be commonly used between right and left ones of the reclining devices. This allows use of a pair of the tooth plates 10 same with each other, in case of employing a right and left pair of the seat reclining devices for the vehicle seat 2 or in case of employing right-left symmetrical seats for a driver seat and a passenger seat, and serves for reduction in number of components and reduction in manufacturing cost and component management cost.

[0075] The configuration of employing the one second projection 22a according to the second embodiment eliminates necessity for arranging the two second projections with a position shift in the radial direction as exemplified in the first embodiment. This facilitates layout in the radial direction, and reduces the reclining section 5 in diameter in the radial direction. <Third Embodiment> Fig. 14 shows a third embodiment of the present invention, which is configured to retract the three lock members 12A to 12C straight inwardly in the radial direction with use of an annular release plate 40 rotatable integrally with the cam 14 which is disclosed as a release plate 50 in drawings in JP 2018-023583 A.

[0076] Fig. 14 is a sectional view of the reclining device, and shows a state in which the external teeth 20 of the lock members 12A to 12C engage with the internal teeth 25 of the tooth plate 10 in lock range R1. In the drawing, a reference numeral 41 represents a third depression formed inside the second depression 27 of the tooth plate 10. A reference numerals 42 represents release grooves formed in the release plate 40.

[0077] According to the third embodiment, the release plate 40 is disposed inside the second depression 27. In view of this, the third depression 41 is shaped annular inside the second depression 27 around the rotational center of the tooth plate 10, and the second restriction part 31 and the second allowance part 33 are formed in an outer circumferential inward surface of the third depression 41. Also the second restriction part 32 may be formed similarly to the first embodiment.

[0078] The three lock members 12A to 12C respectively includes second projections structured to engage with the release grooves 42 of the release plate 40 of the release plate 40, separately from the first projections 21a to 21c structured to engage with the first restriction parts 29. The second projection 22a of the lock member 12A projecting in the axial direction is structured to intrude into an interior of the third depression 41 and face the second allowance part 33 and the second restriction part 31 in the radial direction.

[0079] The two second projections 22a and 22b may be formed in the two adjacent lock members 12A and 12B similarly to the first embodiment. In such case, the second allowance part 33 and the two second restriction parts 31 and 32 are formed stepwise (i.e., arranged to form steps) in the outer circumferential inward surface of the third depression 41 as shown in Fig. 6 and Fig. 7 of the first embodiment. The two second projections 22a and 22b are arranged with a position shift in the radial direction, and also the release grooves 42 are arranged with a position shift in the radial direction.

[0080] The other configurations of the third embodiment are same with the first and second embodiments, which present the effects same with the first embodiment. <Fourth Embodiment> Fig. 15 shows a fourth embodiment of the present invention, which is configured to retract the lock members 12A to 12C straight inwardly in the radial direction with use of a cam 14 in drawings in JP 2009-118940 A. In the state of Fig. 15, the external teeth 20 of the lock members 12A to 12C and the internal teeth 25 of the tooth plate 10 are in engagement with each other in the lock range R1.

[0081] The fourth embodiment employs a guide plate 43 disposed inside the second depression 27 and structured to rotate integrally with the tooth plate 10. The guide plate 43 includes a guide hole 44 having an arc shape around the rotational center of the tooth plate 10. The second allowance part 33 and the second restriction part 31 are formed in an outer circumferential surface of the guide hole 44.

[0082] The three lock members 12A to 12C respectively include the first projections 21a to 21c, and the one lock member 12A includes in its inner side the second projection 22a structured to engage with the guide hole 44. The second projection 22a projecting in the axial direction is inserted in the guide hole 44, and is structured to face the second allowance part 33 and second restriction part 31 in the radial direction. Otherwise, it is allowed to form the two second projections 22a and 22b respectively in the two lock members 12A and 12B similarly to the first embodiment.

[0083] In such case, the second allowance part 33 and the second restriction part 31 are formed stepwise (i.e., arranged to form steps) in an outer circumferential inward surface of the guide hole 44 as shown in Fig. 6 and Fig. 7 of the first embodiment. The two second projections 22a and 22b are arranged with a position shift in the radial direction.

[0084] Also it is allowed to eliminate the guide plate driving rotor and form the outer circumferential inward surface of the guide hole 44 such that a part of the tooth plate 10 projects toward the second depression 27.

[0085] The other configurations of the fourth embodiment are same with the first embodiments, which present the effects same with the first embodiment.

[0086] The present invention is not limited to the above embodiments.

[0087] The following describes exemplary aspects of a reclining device for a vehicle sheet according to the above embodiments.

[0088] According to one aspect of the present invention, a reclining device for a vehicle seat includes: a base member fixed to a first one of a lower bracket of a seat cushion and an upper bracket of a seat back; a tooth member fixed to a second one of the lower bracket and the upper bracket, disposed to overlap with the base member, and structured to rotate relatively with respect to the base member; a first depression shaped circular, formed inside an outer periphery of the tooth member, and centered at a rotational center of the tooth member; internal teeth formed in an inward peripheral surface of the first depression; lock members disposed between the base member and the tooth member and arranged in a circumferential direction, wherein each of the lock members includes external teeth movable in a radial direction so as to engage with the internal teeth at a lock position and release the engagement at an unlock position; a cam disposed radially inside with respect to the lock members and structured to cause the lock members to move between the lock positions and the unlock positions; and a bias member biasing the lock members via the cam in a lock direction that is a direction for engagement of the internal teeth and the external teeth. The tooth member includes a second depression shaped annular, formed radially inside the first depression, and centered at the rotational center of the tooth member. Each of the lock members includes a first projection that projects toward the second depression and is structured to face an outer side inward peripheral surface of the second depression in the radial direction. The second depression includes first allowance parts and first restriction parts. The first allowance parts are structured to respectively face the first projections via gaps and allow the lock members to move to the lock positions, in a lock range that is set in a rearward inclination side from an initial-stage lock position of the seat back with respect to the seat cushion. The first restriction parts are structured to be positioned radially inside with respect to the first allowance parts and respectively contact with the first projections in the radial direction and restrict movement of the first projections in the engagement direction, in a first angular range that is set in a forward inclination side from the initial-stage lock position of the seat back with respect to the seat cushion. At least one of the lock members includes a second projection that is positioned radially inside with respect to the first projection and projects to an inside of the second depression. The tooth member includes a second restriction part. The second restriction part is structured to contact with the second projection of the one of the lock members at a position radially inside with respect to a position of contact between the first projection and the first restriction part, in a second angular range that is set in a further forward inclination side from a position at least partially overlapping with the first angular range set in the forward inclination side from the initial-stage lock position of the seat back.

[0089] The above aspect of the invention allows the one lock member including the second projection to smoothly shift from a state of the first projection riding on the first restriction part to a state of the second projection riding on the second restriction part, in the second angular range that is set in a further forward inclination side from a position at least partially overlapping with the first angular range set in the forward inclination side from the initial-stage lock position of the seat back. This allows the lock members to be maintained at the unlock state, even if the first projections of the lock members respectively get over the first restriction parts facing the first projections and move to the first allowance parts adjacent to the first restriction parts from the forward inclination direction.

[0090] Furthermore, upon rotating rearward the seat back from a forward inclination position and locking the seat back in the lock range, all of the first projections of the lock members contact with the first restriction parts in the first angular range, and thereafter the external teeth of the lock members engage with the internal teeth of the tooth member at an initial lock position in the lock range (i.e., at the initial-stage lock position). This serves to stabilize timing of engagement between the external teeth and the internal teeth, and shorten distances between the external teeth and the internal teeth in a state of contact between the first projections and the first restriction parts and thereby reduce occurrence of tooth skipping upon return from a free region (i.e., the free range) to a lock region (i.e., the lock range).

[0091] Moreover, in case of insufficiency in retraction of the lock members in the engagement release direction (i.e., the radially inward direction) with use of an operational member upon forward inclination rotation of the seat back from the lock range to the first angular range and the second angular range, the first projections of the lock members at this position distribute and receive collision load although the first projections may collide with side surfaces of the first restriction parts. This serves to suppress occurrence of compression and / or deformation of the first projections and the first restriction parts.

[0092] According to another favorable aspect, the second restriction part includes a slope. The slope is structured to cause the one of the lock members to move inwardly in the radial direction being a direction for release of engagement of the external teeth and the internal teeth, with respect to the position of contact between the first projection and the first restriction part, in response to rotation of the seat back in a forward inclination direction, at least in a range in which the first angular range and the second angular range overlap with each other.

[0093] This aspect of the invention serves to place a position of the one lock member in a state the second projection in contact with the second restriction part, more inwardly in the radial direction (i.e., in a direction toward an unlock position), with respect to a position of the one lock member in a state of the first projection in contact with the first restriction part. This prevents a dragging noise caused due to contact between the internal teeth of the tooth member and the external teeth of the other lock members including no second projection, even if the other lock members move outwardly in the radial direction via gaps with the cam, in the second angular range.

[0094] Furthermore, upon raising and rotating the seat back from the most-forward-inclined position in the second angular range to the first angular range, the second projection serves to cause the lock members to smoothly move in a direction for contact between the first projections and the first restriction parts, due to shift via the slope, from a state of the second projection of at least one lock member in contact with the second restriction part, to a state of the first projections in contact with the first restriction parts.

[0095] Moreover, upon forward inclination rotation of the seat back from the lock range to the first angular range and the second angular range, even in case of the second projection of the at least one lock member being at a position to expect collision with the second restriction part, the slope of the second restriction part causes the second projection to move in the contact direction without collision, and allows the seat back to smoothly incline forward.

[0096] According to still another favorable aspect, the slope of the second restriction part is structured to contact with the second projection of the one of the lock members and thereby: cause at least one of the first projections of the lock members to face the first restriction part in the radial direction via a gap, in case that the seat back is at a forward-inclination-side end position of the first angular range; and in response to rotation of the seat back in a rearward inclination direction from the forward-inclination-side end position, cause the first projections of the lock members to move outwardly in the radial direction and contact with the first restriction parts at a middle position in the first angular range.

[0097] According to this aspect, upon rotation of the seat back from the free range to the lock range, the first projections of the lock members are respectively positioned apart from the first restriction parts in the unlock direction via radial gaps, in a state of the seat back at the most-forward-inclined position in the second angular range. Then, the second projection moves along the slope of the second restriction part in the radially outward direction being the engagement direction. The first projections contact with the first restriction parts at a middle position in the first angular range. At a most-forward-inclination lock position within the lock range, the first projections depart from the first restriction parts, the lock members moves outwardly in the radial direction, and the seat back is locked at the initial-stage lock position. This allows the seat back to smoothly incline rearward. According to still another favorable aspect, each of the first restriction parts of the tooth member and a corresponding one of the first projections of the lock members are same with each other in position in the radial direction with respect to the rotational center of the tooth member. The first restriction parts of the tooth member and the first projections of the lock members respectively facing each other are arranged to depart from each other at a same position, at least in a first orientation to rotate the seat back in a rearward inclination direction, out of orientations in a rotational direction of the tooth member.

[0098] This aspect of the invention causes the first projections of the lock members to respectively depart from the corresponding first restriction parts at a same timing, upon shift from the free range (i.e., the first angular range R2) to the lock range. This serves to stabilize the timing of engagement of the lock members. According to still another favorable aspect, each of the lock members is supported by a shaft formed in the base member, wherein the external teeth and the first projection of the each of the lock members is positioned in a first side across the shaft in a rotational direction of the tooth member. The second projection of the at least one of the lock members is positioned in a second side across the shaft in the rotational direction of the tooth member. The second restriction part of the tooth member is formed in an inner circumferential wall surface of the second depression.

[0099] This aspect of the invention provides the outer circumferential wall surface and the inner circumferential wall surface of the second depression of the tooth member with the first restriction parts and the second restriction part respectively, and serves for reduction in length in the axial direction and the radial direction. This serves to reduce the reclining device in size.

[0100] According to still another favorable aspect, the lock members include a first lock member, a second lock member, and a third lock member. Each of the first lock member and the second lock member includes the second projection. The tooth member includes a pair of the second restriction parts each of which radially faces a corresponding one of the second projections of the first and second lock members in the second angular range of the seat back. The third lock member is positioned in an upper side with respect to the rotational center of the tooth member.

[0101] According to this aspect of the invention, the first and second lock members are restricted in movement in the radially outward direction (i.e., the direction for engagement between the external teeth and the internal teeth) due to contact between the second projections of the first and second lock members and the second restriction parts , in a free range in which the first projections are apart from the first restriction parts in the radial directions (i.e., a part of the second angular range in a further forward inclined direction with respect to the lock range). The third lock member is positioned in the upper side with respect to the rotational center of the tooth member, and in the free region, is retained in a lower position due to gravity and suppressed from moving upward. This serves to suppress a dragging noise caused due to contact between the external teeth of the first, second, and third lock members and the internal teeth of the tooth member.

[0102] Furthermore, in the second angular range, the lock members do not move in the direction for engagement with the external teeth (i.e., the radially outward direction). Thus, the contact between the second projections and the second restriction parts in the radial direction with respect to the rotational center of the tooth member allows radial positions of the first and second lock members to approach radial positions of contact between the first projections and the first restriction parts. This serves for reduction of the reclining device in radial size. According to still another favorable aspect, the pair of the second restriction parts is different from each other in length in the radial direction from the rotational center of the tooth member. The tooth member includes a second allowance part between the pair of the second restriction parts, and includes steps each of which is formed between the second allowance part and a corresponding one of the pair of the second restriction parts continuously in the circumferential direction. The second projection of a first one of the first and second lock members facing a greater radius one of the second restriction parts in the second angular range contacts with the greater radius one of the second restriction parts and thereby restricts movement of the first one of the first and second lock members in the engagement direction, in the second angular range, while facing a less radius one of the second restriction parts via a gap and thereby allowing movement of the first one of the first and second lock members in the engagement direction, in the lock range. The second projection of a second one of the first and second lock members facing the less radius one of the second restriction parts in the second angular range contacts with the less radius one of the second restriction parts and thereby restricts movement of the second one of the first and second lock members in the engagement direction, in the second angular range, while facing the second allowance part via a gap and thereby allowing movement of the second one of the first and second lock members in the engagement direction, in the lock range.

[0103] According to this aspect of the invention, the inner side outward peripheral surface of the second depression includes the two second restriction parts and the one second allowance part. This allows setting of a sufficient free range, and thereby serves for reduction of the reclining device in radial size.

[0104] 1 Reclining Device 3 Seat Cushion 4 Seat Back 5 Reclining Section 6 Lower Bracket 7 Upper Bracket 9 Base Plate (Base Member) 10 Tooth Plate (Tooth Member) 12A, 12B, 12C Lock Members 13 Spiral Springs (Bias Members) 14 Cam 20 External Teeth 21a, 21b, 21c First Projections 22a, 22b Second Projections 25 Internal Teeth 26 First Depression 27 Second Depression 27a Outer Circumferential Wall Surface (Inner Peripheral Surface of First Depression) 27b Inner Circumferential Wall Surface 28 First Allowance Parts 29 First Restriction Parts 31, 32 Second Restriction Part 33 Second Allowance Part 34, 35, 36 Steps 37, 38, 39 Slopes

Claims

1. A reclining device for a vehicle seat comprising: a base member fixed to a first one of a lower bracket of a seat cushion and an upper bracket of a seat back; a tooth member fixed to a second one of the lower bracket and the upper bracket, disposed to overlap with the base member, and structured to rotate relatively with respect to the base member; a first depression shaped circular, formed inside an outer periphery of the tooth member, and centered at a rotational center of the tooth member; internal teeth formed in an inward peripheral surface of the first depression; lock members disposed between the base member and the tooth member and arranged in a circumferential direction, wherein each of the lock members includes external teeth movable in a radial direction so as to engage with the internal teeth at a lock position and release the engagement at an unlock position; a cam disposed radially inside with respect to the lock members and structured to cause the lock members to move between the lock positions and the unlock positions; and a bias member biasing the lock members via the cam in a lock direction that is a direction for engagement of the internal teeth and the external teeth; wherein: the tooth member includes a second depression shaped annular, formed radially inside the first depression, and centered at the rotational center of the tooth member; each of the lock members includes a first projection that projects toward the second depression and is structured to face an outer side inward peripheral surface of the second depression in the radial direction; the second depression includes first allowance parts and first restriction parts; the first allowance parts are structured to respectively face the first projections via gaps and allow the lock members to move to the lock positions, in a lock range that is set in a rearward inclination side from an initial-stage lock position of the seat back with respect to the seat cushion; the first restriction parts are structured to be positioned radially inside with respect to the first allowance parts and respectively contact with the first projections in the radial direction and restrict movement of the first projections in the engagement direction, in a first angular range that is set in a forward inclination side from the initial-stage lock position of the seat back with respect to the seat cushion; at least one of the lock members includes a second projection that is positioned radially inside with respect to the first projection and projects to an inside of the second depression; the tooth member includes a second restriction part; and the second restriction part is structured to contact with the second projection of the one of the lock members at a position radially inside with respect to a position of contact between the first projection and the first restriction part, in a second angular range that is set in a further forward inclination side from a position at least partially overlapping with the first angular range set in the forward inclination side from the initial-stage lock position of the seat back.

2. The reclining device as claimed in claim 1, wherein: the second restriction part includes a slope; and the slope is structured to cause the one of the lock members to move inwardly in the radial direction being a direction for release of engagement of the external teeth and the internal teeth, with respect to the position of contact between the first projection and the first restriction part, in response to rotation of the seat back in a forward inclination direction, at least in a range in which the first angular range and the second angular range overlap with each other.

3. The reclining device as claimed in claim 2, wherein the slope of the second restriction part is structured to contact with the second projection of the one of the lock members and thereby: cause at least one of the first projections of the lock members to face the first restriction part in the radial direction via a gap, in case that the seat back is at a forward-inclination-side end position of the first angular range; and in response to rotation of the seat back in a rearward inclination direction from the forward-inclination-side end position, cause the first projections of the lock members to move outwardly in the radial direction and contact with the first restriction parts at a middle position in the first angular range.

4. The reclining device as claimed in claim 1, wherein: each of the first restriction parts of the tooth member and a corresponding one of the first projections of the lock members are same with each other in position in the radial direction with respect to the rotational center of the tooth member; and the first restriction parts of the tooth member and the first projections of the lock members respectively facing each other are arranged to depart from each other at a same position, at least in a first orientation to rotate the seat back in a rearward inclination direction, out of orientations in a rotational direction of the tooth member.

5. The reclining device as claimed in claim 1, wherein: each of the lock members is supported by a shaft formed in the base member, wherein the external teeth and the first projection of the each of the lock members is positioned in a first side across the shaft in a rotational direction of the tooth member; the second projection of the at least one of the lock members is positioned in a second side across the shaft in the rotational direction of the tooth member; and the second restriction part of the tooth member is formed in an inner circumferential wall surface of the second depression.

6. The reclining device as claimed in claim 1, wherein: the lock members include a first lock member, a second lock member, and a third lock member; each of the first lock member and the second lock member includes the second projection; the tooth member includes a pair of the second restriction parts each of which radially faces a corresponding one of the second projections of the first and second lock members in the second angular range of the seat back; and the third lock member is positioned in an upper side with respect to the rotational center of the tooth member.

7. The reclining device as claimed in claim 6, wherein: the pair of the second restriction parts is different from each other in length in the radial direction from the rotational center of the tooth member; the tooth member includes a second allowance part between the pair of the second restriction parts, and includes steps each of which is formed between the second allowance part and a corresponding one of the pair of the second restriction parts continuously in the circumferential direction; the second projection of a first one of the first and second lock members facing a greater radius one of the second restriction parts in the second angular range contacts with the greater radius one of the second restriction parts and thereby restricts movement of the first one of the first and second lock members in the engagement direction, in the second angular range, while facing a less radius one of the second restriction parts via a gap and thereby allowing movement of the first one of the first and second lock members in the engagement direction, in the lock range; and the second projection of a second one of the first and second lock members facing the less radius one of the second restriction parts in the second angular range contacts with the less radius one of the second restriction parts and thereby restricts movement of the second one of the first and second lock members in the engagement direction, in the second angular range, while facing the second allowance part via a gap and thereby allowing movement of the second one of the first and second lock members in the engagement direction, in the lock range.

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