Reclining device and seat

Abstract

A reclining mechanism (6) comprises: four lock gears (60A-60D) that mesh with internal teeth (32) of an internal gear (30); and a wedge member (80) that presses two main lock gears (60A, 60C) among the four lock gears (60A-60D). The main lock gears (60A, 60C) are pushed radially outward while being inclined by an action of a cam (50), and the cam (50) presses both the main lock gears (60A, 60C) and the wedge member (80) at the meshing position of the main lock gears (60A, 60C).

Description

Reclining devices and seats

[0001] The present invention relates to a reclining device and a seat equipped with the reclining device.

[0002] 2. Description of the Related Art Conventional vehicle seats include seats in which the seat back (backrest) is tiltable in the forward and backward directions relative to the seat cushion (seat portion) and is equipped with a reclining device that fixes the seat back at any tilt angle.

[0003] For example, the reclining device 90 described in Patent Document 1 includes a guide bracket 91, an internal gear 92 having internal teeth 92a, three lock gears 93 (pole), a cam 95, and three wedge members 94, as shown in Figures 13 and 14.

[0004] The guide bracket 91 is a generally disk-shaped member fixed to the frame of the seat cushion, and has three pairs of guide walls 91 a, 91 b that extend radially. The three pairs of guide walls 91 a, 91 b are arranged so as to be spaced apart from each other in the circumferential direction of the guide bracket 91.

[0005] The internal gear 92 is a member fixed to the seat back, and has internal teeth 92a formed on the entire inner circumferential surface.

[0006] The three lock gears 93 each have external teeth 93a that can mesh with the internal teeth 92a of the internal gear 92. The three lock gears 93 are arranged spaced apart in the circumferential direction of the internal gear 92, and are movable radially along guide walls 91a, 91b that extend radially between an engagement position where the external teeth 93a and the internal teeth 92a mesh with each other and a release position where the engagement is released.

[0007] Furthermore, each of the three lock gears 93 has, on the opposite side of the external teeth 93a, i.e., on the radially inner side, a cam abutment portion 93b that faces the cam 95 and a pressed surface 93c that is pressed by the wedge member 94. The cam abutment portion 93b and the pressed surface 93c are spaced apart from each other in the circumferential direction.

[0008] The cam 95 is rotatable relative to the guide bracket 91 between a predetermined lock angle and a release angle, and by rotating from the release angle to the lock angle, the three lock gears 93 move radially from the release position to the engagement position.

[0009] The cam 95 has a disk-shaped main body 95a and three sets of L-shaped hooks 95b and shoulders 95c that protrude radially outward from the main body 95a at positions facing each of the three lock gears 93. The shoulders 95c press the lock gear 93 radially outward while abutting against the cam abutment portions 93b of the lock gear 93 at a contact point HP while the cam 95 rotates in the predetermined lock direction R from the release angle to just before the lock angle (the position at angle θ1 in FIG. 13 ). Furthermore, as shown in FIG. 14 , when the cam 95 reaches the lock angle θ2, the shoulders 95c are separated from the cam abutment portions 93b by a gap g.

[0010] Each of the three wedge members 94 is disposed at a position sandwiched between the guide wall 91a, the pressed surface 93c of the lock gear 93, and the hook 95b of the cam 95. When the cam 95 rotates from the release angle to the lock angle θ2 in FIG. 14 , the wedge members 94 are pressed by the outer circumferential surface while contacting the outer circumferential surface of the hook 95b of the cam 95 at a contact point HP, and move radially along the guide wall 91a. As a result, the wedge members 94 apply a pressing force to the pressed surface 93c of the lock gear 93 in a direction that is radially outward and inclined circumferentially, thereby pressing the lock gear 93 radially outward.

[0011] Therefore, in the above-described reclining device 90, while the cam 95 rotates from the release angle to the lock angle θ2 (i.e., in the lock direction R), the shoulder 95c of the cam 95 pushes the lock gear 93 radially outward to the angle θ1, which is just before the lock angle θ2, and at the lock angle θ2, the shoulder 95c moves away from the lock gear 93. During this time, the outer peripheral surface of the hook 95b of the cam 95 continues to push the wedge member 94 radially until the cam 95 reaches the lock angle θ2, thereby moving the lock gear 93 radially outward to the meshing position (i.e., the position where the external teeth 82 and the internal teeth 96a mesh).

[0012] Therefore, when the cam 95 reaches the lock angle θ2 and the lock gear 93 is fully meshed with the internal gear 92, the cam 95 presses the lock gear 93 only via the wedge member 94. As a result, the lock gear 93 is pressed radially outward by the pressing force received from the wedge member 94, and is also pressed against the guide wall 91b on the opposite side from the wedge member 94, thereby suppressing rattling of the lock gear 93 in the locked state.

[0013] 14 , the lock gear 93 receives a pressing force from the wedge member 94, thereby preventing rattling of the lock gear 93. However, the shoulder 95c of the cam 95 is separated from the cam abutment portion 93b of the lock gear 93. Therefore, if a large load is applied to the seat back and a large rotational force acts on the reclining device 90, it may become impossible to maintain proper meshing between the lock gear 93 and the internal gear 92 until the gap between the lock gear 93 and the cam 95 is eliminated. As a result, it is difficult to maintain the locking strength of the reclining device 90.

[0014] 13, i.e., the state in which the cam 95 is in contact with and pressing radially outward against both the lock gear 93 and the wedge member 94 at the contact point HP. However, with this configuration, if the cam 95 contacts the lock gear 93 before the wedge member 94 due to variations in part precision or the like, it may not be possible to reliably prevent the wobbling of the lock gear 93 caused by the wedge member 94.

[0015] Patent No. 5638994

[0016] The present invention has been made in consideration of the above circumstances, and aims to provide a reclining device that can maintain locking strength while reliably suppressing rattling of the locking gear using a wedge member in the locked state.

[0017] The reclining device of the present invention includes a guide bracket fixed to one of the seat cushion and the seat back, an internal gear fixed to the other of the seat cushion and the seat back at a position opposite to the guide bracket, the internal gear being rotatable relative to the guide bracket and having a plurality of internal teeth, and a plurality of lock gears each having a plurality of external teeth that can mesh with some of the internal teeth of the internal gear, the lock gears being spaced apart in the circumferential direction of the internal gear and movable in the radial direction of the guide bracket between an engagement position where the external teeth and the internal teeth mesh with each other and a release position where the meshing is released, and a lock gear that rotates to move the plurality of lock gears radially from the release position to the engagement position. a lock spring that rotates the cam in a direction in which the plurality of lock gears move toward the meshing position; and a wedge member that presses at least one of the plurality of lock gears by receiving a radially outward pressing force from the cam, wherein the guide bracket has a plurality of pairs of opposing guide wall portions that guide the plurality of lock gears in the radial direction, the wedge member is interposed between one of the guide wall portions and the lock gear and presses the lock gear by receiving a pressing force from the cam, the lock gear is pushed outward in the radial direction while tilting by the cam, and the cam presses both the lock gear and the wedge member when locked, i.e., at the meshing position of the lock gear.

[0018] 1 is a perspective view showing the overall configuration of a seat equipped with a reclining device according to an embodiment of the present invention. It is an exploded perspective view of the reclining mechanism of FIG. 1. It is a view showing the completed state of the reclining mechanism, which combines the internal gear, a pair of main lock gears, a pair of sub-lock gears, a pair of wedge members, a cam, a guide bracket, and an attachment ring of FIG. 2. It is an enlarged view showing the state in which the upper main lock gear of FIG. 3 is in an engaged position. It is an enlarged view of a main part showing a configuration in which one of a pair of sliding contact surfaces of the main lock gear opposite the wedge member has a protrusion that protrudes toward the opposing guide wall portion. It is an enlarged view showing a state in which, among the multiple external teeth of the main lock gear of FIG. 4, the external teeth within a range AR1 including the external teeth at the center in the width direction of the main lock gear and the internal teeth of the internal gear are closely meshed with almost no gap. It is an enlarged view showing a state in which, among the multiple external teeth of the main lock gear of FIG. 4, the external teeth within a range AR2 including the external teeth at the left end in the width direction of the main lock gear are meshed with the internal teeth of the internal gear with a gap. 9 is an enlarged view showing a state in which the external teeth within a range AR3 including the external teeth at the right end of the width direction of the main lock gear among the multiple external teeth of the main lock gear in FIG. 4 are meshed with the internal teeth of the internal gear with a gap. This is a view showing the reclining mechanism of FIG. 3 in an unlocked state. This is a view showing a state in which the cam presses the main lock gear via a wedge member while moving from the unlocked state to the locked state in FIG. 9. This is an enlarged view showing that the upper main lock gear of FIG. 3 is in a position just before the meshing position, and the force of the cam pressing the lock gear via the wedge member causes the external teeth within a range AR1 to mesh with the internal teeth while the lock gear tilts radially away from the wedge member to abut against the cam. This is an enlarged view showing a state in which the upper main lock gear of FIG. 3 is in an meshing position, and the cam presses both the wedge member and the lock gear. This is a cross-sectional view showing the structure of a conventional reclining device, showing the cam just before meshing with the lock gear. FIG. 14 is a cross-sectional view showing the cam in the conventional reclining device of FIG. 13 in a state of meshing with the lock gear.

[0019] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] As shown in FIG. 1 , the seat 1 of this embodiment is a seat for a vehicle or the like, and includes a seat cushion 2 that supports the buttocks of a seated occupant, a seat back 3 that is disposed at the rear of the seat cushion 2 to support the back of the seated occupant and that can be tilted in the front-to-rear direction X of the seat 1 relative to the seat cushion 2, a slide device 4 attached to the bottom of the seat cushion 2, and a reclining device 5.

[0021] The slide device 4 is configured to guide the seat cushion 2 so that it can slide in the front-rear direction X of the seat 1 and to fix the seat cushion 2 at any position. Note that the slide device 4 is not essential for the seat of the present invention and may be omitted.

[0022] The reclining device 5 has, as its main component, a reclining mechanism 6 that can fix the seat back 3 at any inclination angle.

[0023] 1, the reclining device 5 of this embodiment includes a pair of reclining mechanisms 6, a connecting rod 7 connected to the pair of reclining mechanisms 6, and a pair of resin bushings 8 fitted near the ends on both sides of the connecting rod 7. The resin bushings 8 may be omitted.

[0024] The pair of reclining mechanisms 6 are disposed on both sides of the seat 1 in the width direction Y. Each reclining mechanism 6 is a mechanism for fixing the seat back 3 at a desired tilt angle.

[0025] As shown in FIGS. 2 to 4, the reclining mechanism 6 includes a disk-shaped guide bracket 20, an internal gear 30 disposed opposite the guide bracket 20 and having internal teeth 32, four lock gears 60A to 60D having external teeth 63 that can mesh with the internal teeth 32, that is, a pair of main lock gears 60A, 60C and a pair of sub-lock gears 60B, 60D, and a cam 50 that moves these four lock gears 60A to 60D in the radial direction of the guide bracket 20. At least one lock spring 40 (two in this embodiment) that rotationally biases the cam 50, a pair of wedge members 80 that are interposed between at least one of the four lock gears 60A to 60D (in this embodiment, the pair of main lock gears 60A, 60C) and the cam 50 and press the pair of main lock gears 60A, 60C, respectively, and an attachment ring 70 that attaches the internal gear 30 to the guide bracket 20. The four lock gears 60A to 60D, the cam 50, the pair of wedge members 80, and the two lock springs 40 are disposed between the guide bracket 20 and the internal gear 30.

[0026] As shown in FIG. 3 , the four lock gears 60A to 60D, i.e., a pair of main lock gears 60A and 60C and a pair of sub lock gears 60B and 60D, are spaced apart in the circumferential direction of the internal gear 30 and are movable in the radial direction of the guide bracket 20 between an engagement position where the external teeth 63 of each of the main lock gears 60A and 60C engage with the internal teeth 32 of the internal gear 30 and a release position where the engagement is released. Specifically, the main lock gears 60A and 60C each have external teeth 63 that can engage with the internal teeth 32, and are lock gears that perform strong engagement when pressed by the cam 50 via the wedge member 80. On the other hand, the sub lock gears 60B and 60D have external teeth 63 that can engage with the internal teeth 32, and are lock gears that mesh with the internal teeth 32 to complement the strong engagement (lock strength) of the main lock gears 60A and 60C. In this embodiment, a small spiral spring is used as the lock spring 40 .

[0027] Here, "strong meshing" of the main lock gears 60A, 60C means that the external teeth 63 and the internal teeth 32 mesh in a state where their respective tooth surfaces come into contact and press against each other. On the other hand, the sub-lock gears 60B, 60D are not required to mesh as strongly as the main lock gears 60A, 60C, where their external teeth 63 and internal teeth 32 press against each other, but rather only need to mesh to complement the strong meshing (locking strength) of the main lock gears 60A, 60C.

[0028] The guide bracket 20 is a plate-shaped member having a circular center hole 22 in the center. The guide bracket 20 of this embodiment is fixed to either the seat cushion 2 or the seat back 3 near the rear of a frame 2 a (see FIG. 1 ) (specifically, a side frame) of the seat cushion 2.

[0029] Specifically, as shown in FIG. 2, the guide bracket 20 has a disk-shaped main body portion 21 with a circular center hole 22 formed in the center, two accommodating portions 23 that each accommodate a lock spring 40, and a flange portion 24 provided along the outer periphery of the main body portion 21.

[0030] Each of the two accommodating portions 23 is recessed toward the outer surface 21 a of the guide bracket 20, opens toward the inner surface 21 b of the main body 21, and communicates with the center hole 22. Therefore, with the spiral portion of the lock spring 40 accommodated in the accommodating portion 23, the outer end portion 41 of the lock spring 40 can protrude into the center hole 22.

[0031] 2 to 4, the guide bracket 20 further has a plurality of guide wall portions 25 (guide portions) on the inner surface 21b of the main body portion 21 that guide the four lock gears 60A to 60D in the radial direction of the guide bracket 20. The plurality of guide wall portions 25 are provided around the center hole 22 at equal intervals in the circumferential direction and extend radially in four directions. More specifically, the plurality of guide wall portions 25 are formed in pairs around the center hole 22 and extend radially in four directions. This makes it possible for the four pairs of guide wall portions 25 to guide the four lock gears 60A to 60D in the radial direction of the guide bracket 20.

[0032] The internal gear 30 is fixed to the other of the seat cushion 2 and the seat back 3 near the lower part of the frame 3a (see Figure 1) (specifically, the side frame) of the seat back 3, at a position opposite the guide bracket 20.

[0033] As shown in FIG. 2 , the internal gear 30 has a recessed portion 31 that is circular when viewed axially from the side where the guide bracket 20 is located and has a generally recessed cross section. Internal teeth 32 are formed around the entire inner circumferential surface of the recessed portion 31. The internal gear 30 is positioned such that the bottom surface of the recessed portion 31 faces the inner surface 21 b of the main body 21 of the guide bracket 20. A through hole 33 is formed in the center of the recessed portion 31. As shown in FIG. 2 , the through hole 33 is positioned so as to overlap a through hole (not shown) in the frame 3 a of the seat back 3. The respective ends of the connect rod 7 and the resin bushing 8 are inserted into the reclining mechanism 6 through the through hole.

[0034] 2, with the guide bracket 20 and the recessed portion 31 of the internal gear 30 facing each other, the peripheral edge of the recessed portion 31 is fitted into the guide bracket 20. This positions the internal gear 30 radially relative to the guide bracket 20.

[0035] Furthermore, a mounting ring 70 is fixed to the flange portion 24 by welding or the like to prevent the internal gear 30 from coming off in the axial direction. As a result, the internal gear 30 is connected to the guide bracket 20 so as to be rotatable relative to the guide bracket 20.

[0036] As shown in FIGS. 2 and 3 , the four lock gears 60A-60D are components (so-called lock plates) having a generally rectangular shape in a plan view, each of which has a plurality of external teeth 63 that can mesh with some of the internal teeth 32 of the internal gear 30. The lock gears 60A-60D are movably arranged along the inner surface 21b of the guide bracket 20, guided radially by the guide wall portion 25 formed on the inner surface 21b. This allows the lock gears 60A-60D to move between an engagement position where the external teeth 63 mesh with the internal teeth 32 and a release position where the engagement is released. An engagement groove 61, cut into a generally arc-shaped groove extending circumferentially of the cam 50, is formed on the inner circumferential surface of each lock gear 60A-60D. The engagement groove 61 is a groove for engaging with an engagement protrusion 52 of the cam 50, which will be described later. Furthermore, by forming the engaged groove 61 extending in the circumferential direction as described above, an approximately L-shaped engaging protrusion 64 is formed on the inner circumferential surface of the lock gears 60A to 60D radially inward of the engaged groove 61.

[0037] 4, the L-shaped engagement protrusion 64 has an outer surface 64a on the inner circumferential side that faces the cam 50. When the lock gears 60A to 60D are in the locked state (engaged position), the outer surface 64a comes into contact with the protrusion 55 of the cam 50 at a contact point P2.

[0038] The multiple lock gears 60A to 60D are composed of a pair of main lock gears 60A, 60C that face each other, and a pair of sub lock gears 60B, 60D that face each other and are spaced 90 degrees circumferentially from the pair of main lock gears 60A, 60C.

[0039] The wedge members 80 are interposed between each of the pair of main lock gears 60A, 60C, the guide wall portion 25, and the cam 50.

[0040] As shown in FIGS. 2 and 3, the pair of main lock gears 60A, 60C are arranged vertically facing each other so as to be aligned linearly with the cam 50 therebetween.

[0041] The pair of sub lock gears 60B, 60D are arranged opposite to the pair of main lock gears 60A, 60C at a distance of 90 degrees in the circumferential direction of the cam 50 and aligned linearly with the cam 50 in between.

[0042] As shown in Figures 2 and 3, a pair of main lock gears 60A, 60C that are aligned vertically and radially opposed to each other are common to the sub lock gears 60B, 60D in that they have the external teeth 63 and engaging protrusions 64 described above, but differ in that they have a pressed surface 67 shown in Figure 4.

[0043] As shown in Fig. 4, the pressed surface 67 is a slope that extends in a direction inclined relative to the radial direction on the inner circumferential side of the main lock gears 60A, 60C, and is the surface that is pressed by the wedge member 80. The pressed surface 67 is located in a position aligned with the engaging protrusion 64 in the circumferential direction. That is, the pressed surface 67 is located close to one guide wall portion 25A of the pair of guide wall portions 25A, 25B, and the engaging protrusion 64 is located close to the other guide wall portion 25B. Note that the lower main lock gear 60C shown in Fig. 3 has the same shape as the upper main lock gear 60A, and therefore both main lock gears 60A, 60C will be described below using Figs. 4 and 11 and 12.

[0044] In this embodiment, the wedge member 80 has a wedge shape that is roughly triangular and pointed, and is interposed between the pressed surface 67 of the main lock gears 60A, 60C and one of the guide wall portions 25 (more specifically, the guide wall portion 25A on the wedge member 80 side in Figure 4), and is arranged in a state where it is sandwiched between the pressed surface 67 and the guide wall portion 25.

[0045] 4, the wedge member 80 has an arcuate cam abutment surface 80a that contacts the cam 50 (specifically, the arcuate outer peripheral surface 52a of the engaging protrusion 52 described below), a guide wall abutment surface 80c that contacts the guide wall portion 25A, and a pressing surface 80b that presses the pressed surfaces 67 of the main lock gears 60A, 60C. The cam abutment surface 80a contacts the arcuate outer peripheral surface 52a of the engaging protrusion 52 of the cam 50 at a contact point P1.

[0046] 4, it is preferable that at least one of the pressing surface 80b and the pressed surface 67 of the main lock gears 60A, 60C has a shape in which at least a portion thereof protrudes in the direction opposite to each other. In this embodiment, the pressing surface 80b is configured as a flat surface, but the pressed surface 67 has a curved surface 67a that protrudes toward the pressing surface 80b on the radially inner side.

[0047] 4, the pressing surface 80b and the pressed surface 67 come into contact at a contact point P3. Note that the contact point P3 is the point where the pressing surface 80b and the pressed surface 67 come into contact when viewed from the axial direction of the internal gear 30, but is a tangent line extending in the thickness direction of the main lock gears 60A, 60C when viewed from the radial direction. Note that both the pressing surface 80b and the pressed surface 67 may have protruding portions that protrude in opposing directions, and the protruding portions may be in point contact with each other.

[0048] As shown in FIG. 11 , at a position immediately before the meshing position, the force of the cam 50 pressing the main lock gears 60A, 60C via the wedge member 80 causes some of the external teeth 63 to mesh with the internal teeth 32, while the main lock gears 60A, 60C tilt radially away from the wedge member, so that the main lock gears 60A, 60C come into contact with the cam 50.

[0049] 11 , the arcuate outer peripheral surface 52a of the engaging projection 52 of the cam 50 contacts the arcuate cam contact surface 80a of the wedge member 80 at contact point P1. Furthermore, the pressing surface 80b of the wedge member 80 contacts the curved surface 67a of the pressed surface 67 of the main lock gear 60A at contact point P3. This allows the cam 50 to press the main lock gear 60A via the wedge member 80. Furthermore, at this time, the main lock gear 60A can tilt in direction S (i.e., in a direction tilting away from the wedge member 80 in the radial direction) with contact point P3 as a fulcrum relative to the wedge member 80.

[0050] 4 and 11, the external teeth 63 located outside an area AR1 including the external tooth 63 at the widthwise center of the main lock gear 60A and in two areas AR2 and AR3 including both widthwise ends of the main lock gear 60A are formed so as to leave gaps between them and the internal teeth 32 of the internal gear 30. Specifically, the centers of the pitch circles are shifted from the center of the internal gear 30 so as to leave gaps G1, G2 (see FIGS. 7 and 8) between the external teeth 63 and the internal teeth 32.

[0051] Therefore, in the main lock gear 60A of this embodiment, the meshing state between the multiple external teeth 63 and the internal teeth 32 of the internal gear 30 differs in the three ranges AR1 to AR3 shown in FIGS.

[0052] That is, in FIGS. 4 and 11, within the range AR1 including the external tooth 63 at the widthwise center of the main lock gear 60A, the center of the pitch circle coincides with the center of the internal gear 30, and therefore, as shown in FIG. 6, the external tooth 63 and the internal tooth 32 mesh closely with almost no gap.

[0053] 4 and 11, within a range AR2 including the external teeth 63 at the left end in the width direction of the main lock gear 60A (i.e., the end on the side where the wedge member 80 is present), the center of the pitch circle is shifted to the right in the width direction from the center of the internal gear 30, so the external teeth 63 and the internal teeth 32 mesh with each other with a large gap G1 between them, as shown in Fig. 7. In Fig. 7, the tooth row of the external teeth 63 is inclined downward relative to the tooth row of the internal teeth 32 as it approaches the left end.

[0054] 4 and 11, within a range AR3 including the external teeth 63 at the right end in the width direction of the main lock gear 60A (i.e., the end opposite the wedge member 80), the center of the pitch circle is shifted to the left in the width direction from the center of the internal gear 30, so as shown in Fig. 8, the external teeth 63 and the internal teeth 32 mesh with each other with a gap G2 that is larger than the meshing state in Fig. 6. In Fig. 8, the tooth row of the external teeth 63 is inclined downward relative to the tooth row of the internal teeth 32 as it approaches the right end.

[0055] As described above, the external teeth 63 in the two ranges AR2 and AR3 that include both widthwise ends of the main lock gear 60A are formed with the centers of their pitch circles shifted from the center of the internal gear 30 so that gaps G1, G2 (see Figures 7 and 8) are formed between the external teeth 63 and the internal teeth 32. This allows the main lock gear 60A to tilt in direction S around point P4, which is the fulcrum within range AR1 that includes the widthwise center of the multiple external teeth 63 and where the main lock gear 60A meshes with the internal teeth 32 with the tightest gap.

[0056] Furthermore, the main lock gears 60A, 60C have a pair of sliding contact surfaces 68 that slidably contact the pair of guide wall portions 25 that sandwich the main lock gears 60A, 60C. Here, the pair of sliding contact surfaces 68 are distinguished by calling the sliding contact surface located closer to the wedge member 80 sliding contact surface 68A and the sliding contact surface located opposite the wedge member 80 sliding contact surface 68B.

[0057] As shown in Fig. 5, of the pair of sliding surfaces 68, the sliding surface 68B located on the opposite side from the wedge member 80 has a protrusion 69 that protrudes toward the opposing guide wall portion 25B. The protrusion 69 contacts the guide wall portion 25B at a contact point P5. As a result, as shown in Fig. 11, the main lock gears 60A, 60C tend to tilt in the direction S with respect to the radially extending guide wall portion 25B, with the contact point P5 as a fulcrum.

[0058] In this embodiment, the protrusion 69 has an outer surface 69a that includes a curved surface that curves toward the opposing guide wall portion 25B, so that the main lock gears 60A, 60C are more likely to tilt.

[0059] As described above, as shown in FIG. 11 , at a position immediately before the meshing position, the main lock gears 60A, 60C are capable of tilting in direction S around the three contact points P3, P4, and P5 as fulcrums while maintaining the state in which the external teeth 63 in range AR1 of the multiple external teeth 63 mesh with the internal teeth 32 due to the force of the cam 50 pressing against the main lock gears 60A, 60C via the wedge member 80, i.e., tilting radially in the opposite direction from the wedge member 80.

[0060] As a result, as shown in Figure 12, when the cam 50 reaches the lock angle and the main lock gears 60A, 60C reach the meshing position, the cam 50 presses both the main lock gears 60A, 60C and the wedge member 80 radially outward, allowing the external teeth 63 of the lock gears 60A, 60C to mesh firmly with the internal teeth of the internal gear 30.

[0061] Specifically, when the engaging projection 52 of the cam 50 contacts the cam abutment surface 80a of the wedge member 80 at contact point P1, the cam 50 presses the wedge member 80, applying a pressing force F1 to the wedge member 80. The pressing force F1 is divided into a component force F11, whereby the wedge member 80 presses the main lock gears 60A, 60C, and a component force F12, whereby the wedge member 80 presses the guide wall portion 25A. The component force F11 is a force that is inclined relative to the radial direction and acts radially outward. Meanwhile, when the projection 55 of the cam 50 contacts the engaging projection 64 of the main lock gears 60A, 60C at contact point P2, the cam 50 presses the main lock gears 60A, 60C, applying a pressing force F2 to the main lock gears 60A, 60C. The pressing force F2 is a force that is slightly inclined relative to the radial direction and acts radially outward.

[0062] Therefore, two forces, namely, a component force F11 and a pressing force F2, are applied from the cam 50 to the main lock gears 60A, 60C. These component force F11 and pressing force F2 make it possible to obtain a force F3 that firmly meshes the external teeth 63 of the main lock gears 60A, 60C in the range AR1 (particularly the external teeth 63 near point P4) with the internal teeth 32 of the internal gear 30, and a force F4 that firmly presses the main lock gears 60A, 60C against the guide wall portion 25B. As a result, the main lock gears 60A, 60C can firmly mesh with the internal gear 30 without wobbling at the meshing position.

[0063] Other configurations are as follows. As shown in Figures 2 and 3, the pair of sub lock gears 60B, 60D, unlike the main lock gears 60A, 60C, have a shape that is integrated with the wedge member 80. That is, the sub lock gears 60B, 60D have, on their radially inner sides, protrusions 65 that protrude radially inward and correspond to the wedge member 80. The radially inner surfaces of the protrusions 65 can come into contact with the cam 50 (specifically, the arc-shaped outer peripheral surface 52a of the engaging protrusions 52 described below).

[0064] The cam 50 is rotatable relative to the guide bracket 20 between a predetermined lock angle and an release angle. As shown in Figures 2 and 3, the cam 50 has a main body 51 and a shaft 53 that protrudes from the main body 51 toward the guide bracket 20 in the axial direction of the cam 50 and is inserted into the center hole 22 of the guide bracket 20.

[0065] The main body 51 has four engaging protrusions 52, which are multiple operating parts that move each of the four lock gears 60A to 60D in the radial direction. The four engaging protrusions 52 extend in a direction that allows them to engage with the engaged grooves 61 (see FIGS. 2 and 3) of the four lock gears 60A to 60D, respectively. More specifically, they extend in a generally arcuate and angular (approximately L-shaped) shape at equal intervals in the circumferential direction. The arcuate outer peripheral surfaces 52a of the four engaging protrusions 52 contact the wedge member 80 adjacent to the pair of main lock gears 60A, 60C and the protrusions 65 of the pair of sub-lock gears 60B, 60D, respectively, to press all of the lock gears 60A to 60D radially outward from the cam 50 and move them to their meshing positions.

[0066] The cam 50 also has protrusions 55 on its outer peripheral surface, located between the four engaging protrusions 52. The protrusions 55 have arc-shaped outer peripheral surfaces 55a. As shown in FIGS. 9 and 10 , two of the protrusions 55 face the engaging protrusions 64 of the main lock gears 60A, 60C while maintaining a gap therebetween until they reach a position immediately prior to the engaging position while the main lock gears 60A, 60C move from the disengaged position to the engaged position. As shown in FIG. 11 , at a position immediately prior to the engaged position, the main lock gears 60A, 60C tilt, causing the protrusions 55 to come into contact with the engaging protrusions 64 of the main lock gears 60A, 60C. At this time, the radially inner outer surface 64a of the engaging protrusions 64 comes into contact with the protrusions 55 of the cam 50 at contact point P2. The remaining two projections 55 face the engaging projections 64 of the sub-lock gears 60B, 60D while maintaining a gap therebetween while the sub-lock gears 60B, 60D move from the release position to the meshing position.

[0067] As shown in Figure 3, a rod engagement hole 54 is formed in the center of the main body 51 of the cam 50. The end of the connect rod 7 in Figure 1 engages with the rod engagement hole 54 through the through hole 33 of the internal gear 30. By manually rotating the connect rod 7, the cam 50 inside the reclining mechanism 6 can be rotated.

[0068] The shaft portion 53 of the cam 50 is configured with a plurality of (two in this embodiment) protrusions that protrude from the main body portion 51 in the axial direction.

[0069] As a result of outer end portion 41 of lock spring 40 engaging with shaft portion 53, lock spring 40 urges cam 50 to rotate in a predetermined direction (lock direction R of cam 50 in FIG. 3) from the release angle toward the lock angle. Specifically, four engaging protrusions 52 of cam 50 press a pair of wedge members 80 that press a pair of main lock gears 60A, 60C and protrusions 65 of a pair of sub lock gears 60B, 60D radially outward from cam 50, and lock spring 40 urges cam 50 to rotate in a direction that moves the external teeth 63 of these lock gears 60A to 60D to meshing positions where they mesh with internal teeth 32 of internal gear 30.

[0070] The cam 50 is rotatably supported relative to the guide bracket 20 by the outer circumferential surface of the shaft portion 53 abutting against the inner circumferential surface of the center hole 22 of the guide bracket 20 .

[0071] In this way, the inner peripheral surface of the center hole 22 of the guide bracket 20 abuts against the outer peripheral surface of the shaft portion 53 , so that the cam 50 is positioned radially relative to the guide bracket 20 .

[0072] As shown in Figure 2, the two lock springs 40 are accommodated in the above-mentioned accommodation portion 23 on the inner surface 21b side of the main body portion 21 of the guide bracket 20, and are thereby evenly arranged circumferentially around the center hole 22, i.e., in this embodiment, on both sides of the center hole 22.

[0073] The lock spring 40 of this embodiment is a spiral spring formed by spirally winding a strip-shaped thin metal plate, and has an outer end 41 and an inner end 42. The inner end 42 engages with an engaging protrusion 23 a provided in a recess of the accommodation portion 23 of the guide bracket 20.

[0074] The outer end 41 is engaged with the shaft 53 of the cam 50. As a result, the two lock springs 40 can each rotate the cam 50 in a direction that displaces the four lock gears 60A to 60D from the release position to the meshing position.

[0075] The reclining mechanism 6 described above switches between a locked state and an unlocked state as follows. In the normal locked state, as shown in Figures 3 and 4, the cam 50 is biased in the locking direction R by the rotational biasing force of the lock spring 40. In this state, the outer peripheral surfaces 52a of the two engaging protrusions 52 of the cam 50 press against a pair of wedge members 80 interposed between the cam 50 and each of the pair of main lock gears 60A, 60C, thereby strongly pushing the pair of main lock gears 60A, 60C radially outward and maintaining them in the meshed position. This not only ensures that the external teeth 63 are firmly meshed with the internal teeth 32 of the internal gear 30, but also reduces (narrows) the widthwise clearance of the main lock gears 60A, 60C, thereby suppressing rattling.

[0076] In the locked state, the protrusion 55 of the cam 50 constantly presses against the L-shaped engaging protrusion 64 of the main lock gears 60A, 60C, but a gap is formed between the protrusion 55 and the outer surface 64a of the L-shaped engaging protrusion 64 of the sub-lock gears 60B, 60D. Therefore, if a large load is input from outside the reclining device 5 when the lock gears 60A to 60D are in the locked state, the protrusion 55 will come into contact with the L-shaped engaging protrusion 64 of the sub-lock gears 60B, 60D, making it possible to maintain the meshed state of the sub-lock gears 60B, 60D even if the meshed state of the main lock gears 60A, 60C is released.

[0077] On the other hand, when a rotational operating force is input to the connect rod 7, the cam 50 rotates in the reverse direction (the direction opposite to the locking direction R in FIG. 3) against the elastic force of the lock spring 40, thereby displacing the four locking gears 60A to 60D toward the center. That is, when the cam 50 rotates in the direction opposite to the locking direction R, the four engaging protrusions 52 of the cam 50 engage with the respective engaged grooves 61 (see FIGS. 2 and 3) of the four locking gears 60A to 60D, drawing the four locking gears 60A to 60D toward the center of the cam 50. This draws the four locking gears 60A to 60D radially inward, displacing them from the meshed position to the released position, and entering the unlocked state shown in FIG.

[0078] 9, the four lock gears 60A to 60D are not in mesh with the internal gear 30. Furthermore, the cam 50 is not in contact with the four lock gears 60A to 60D and the wedge member 80, or even if it is in contact with them, it does not apply a pressing force to the lock gears 60A to 60D and the wedge member 80. Therefore, the guide bracket 20 and the internal gear 30 are in a state where they can rotate relative to each other, and the seat back 3 can be adjusted to any angle.

[0079] After the seat back 3 has been adjusted to the desired angle, if the rotational operating force on the connect rod 7 is released, the rotational biasing force of the lock spring 40 causes the cam 50 to rotate in the locking direction R, as shown in Figure 10, and the cam 50 presses the wedge member 80 radially outward, thereby moving the main lock gears 60A, 60C radially outward while pressing them against the guide wall portion 25. At the same time, the cam 50 abuts against the protrusions 65 of the sub-lock gears 60B, 60D, moving the sub-lock gears 60B, 60D radially outward. This allows the reclining mechanism 6 to return to the locked state described above.

[0080] (Features of the Present Embodiment) (1) In the reclining mechanism 6 of the present embodiment, the main lock gears 60A, 60C are configured to be pushed radially outward while tilting by the cam 50. Specifically, as shown in Fig. 11 , the cam 50 presses the main lock gears 60A, 60C via the wedge member 80, causing some of the external teeth 63 of the multiple external teeth 63 to mesh with the internal teeth 32, causing the main lock gears 60A, 60C to tilt radially away from the wedge member 80 and abut against the cam 50 at a position immediately before the meshing position. Furthermore, as shown in Fig. 12 , the cam 50 presses both the engaging protrusions 64 of the main lock gears 60A, 60C and the wedge member 80 at the lock angle.

[0081] With this configuration, as the cam 50 rotates from the release angle to the lock angle, the lock gears 60A-60D move from the release position to the engagement position. During this movement, the cam 50 presses the main lock gears 60A, 60C via the wedge member 80, causing some of the external teeth 63 of the main lock gears 60A, 60C to mesh with the internal teeth 32 of the internal gear 30 while tilting the main lock gears 60A, 60C radially away from the wedge member 80, allowing them to abut against the cam 50 just before the engagement position. This prevents the cam 50 from abutting the main lock gears 60A, 60C before the wedge member 80, making it possible for the wedge member 80 to reliably suppress rattle of the main lock gears 60A, 60C.

[0082] When the cam 50 reaches the lock angle and the main lock gears 60A, 60C reach the meshing position, the cam 50 presses both the main lock gears 60A, 60C and the wedge member 80 at the lock angle, so that the locked state can be maintained even if a large rotational force acts on the reclining device.

[0083] Therefore, in the reclining device described above, it is possible to reliably suppress rattle of the main lock gears 60A, 60C by the wedge member 80 while maintaining lock strength in the locked state.

[0084] (2) In the reclining mechanism 6 of this embodiment, the main lock gears 60A, 60C have a pair of sliding surfaces 68 that slidably contact the pair of guide wall portions 25 that sandwich the main lock gears 60A, 60C. As shown in FIG. 5 , the sliding surface 68B of the pair of sliding surfaces 68 that is located on the opposite side from the wedge member 80 has a protruding portion 69 that protrudes toward the opposing guide wall portion 25.

[0085] In this configuration, when main lock gears 60A, 60C receive a pressing force from wedge member 80, sliding surface 68 and the entire main lock gears 60A, 60C tend to tilt around protruding portion 69 of sliding surface 68 located on the opposite side from wedge member 80 (specifically, around contact point P5), making it possible for cam 50 to reliably press main lock gears 60A, 60C together with wedge member 80.

[0086] (3) In the reclining mechanism 6 of this embodiment, the protrusion 69 has an outer surface 69 a that includes a curved surface that curves toward the opposing guide wall portion 25 .

[0087] In this configuration, the protrusion 69 tilts smoothly while the curved outer surface 69a of the protrusion 69 abuts against the guide wall portion 25, making it even easier for the main lock gears 60A, 60C to tilt.

[0088] (4) In the reclining mechanism 6 of this embodiment, of the multiple external teeth 63 shown in Figures 4 and 11, the external teeth 63 located outside the range AR1 including the external teeth 63 at the widthwise center of the main lock gears 60A, 60C and in two ranges AR2 and AR3 including both widthwise ends of the main lock gears 60A, 60C are formed so that gaps G1, G2 (see Figures 7 and 8) are formed between the external teeth 63 and the internal teeth 32. Specifically, the centers of the pitch circles of the external teeth 63 located in the two ranges AR2 and AR3 including both widthwise ends of the main lock gears 60A, 60C are shifted from the center of the internal gear 30.

[0089] In this configuration, the gaps G1 and G2 allow the external teeth 63 of the main lock gears 60A and 60C to rotate on the internal teeth 32 of the internal gear 30, making it possible for the main lock gears 60A and 60C to easily tilt while meshed with the internal teeth 32.

[0090] (5) In the reclining mechanism 6 of this embodiment, at least one of the pressing surface 80b and the pressed surface 67 has portions (curved surfaces 67a in this embodiment) that protrude in opposing directions.

[0091] In this configuration, as shown in FIG. 11, the pressing surface 80b of the wedge member 80 and the pressed surfaces 67 of the main lock gears 60A, 60C are in point contact at contact point P3 (actually, they are in line contact over the plate thickness), which makes it even easier for the main lock gears 60A, 60C to tilt at a position just before the meshing position.

[0092] (6) In the reclining mechanism 6 of this embodiment, the pressed surface 67 includes a curved surface 67a that protrudes in a direction facing the pressing surface 80b. In this configuration, the curved surface 67a of the pressed surface 67 a abuts against the pressing surface 80b of the wedge member 80, making it even easier for the main lock gears 60A, 60C to tilt.

[0093] (7) In the reclining mechanism 6 of this embodiment, the multiple lock gears 60A to 60D are composed of a pair of opposing main lock gears 60A, 60C and a pair of opposing sub-lock gears 60B, 60D that are circumferentially spaced 90 degrees apart from the pair of main lock gears 60A, 60C. The wedge member 80 is interposed between each of the pair of main lock gears 60A, 60C and the cam 50.

[0094] With this configuration, when the reclining mechanism 6 is in the locked state, the pair of main lock gears 60A, 60C can receive the pressing force of the cam 50 directly and indirectly via the wedge member 80. This allows the main lock gears 60A, 60C to suppress wobbling while maintaining a strong meshing state with the internal gear 30. On the other hand, when a large rotational force is applied to the reclining mechanism 6, the sub-lock gears 60B, 60D, along with the main lock gears 60A, 60C, also act to maintain the locked state.

[0095] (8) The seat 1 of this embodiment includes the seat cushion 2, the seat back 3 that is disposed at the rear of the seat cushion 2 and is tiltable in the front-to-rear direction of the seat, and the reclining mechanism 6 that fixes the seat back 3 at a desired tilt angle. Therefore, because the seat 1 includes the reclining mechanism 6, it is possible to reliably suppress rattling of the main lock gears 60A, 60C by the wedge member 80 while maintaining lock strength in the locked state.

[0096] (Modifications) (A) The shape of the protrusion 69 on the sliding surface 68B of the main lock gears 60A, 60C is not particularly limited in the present invention as long as it protrudes relative to the guide wall portion 25B. Therefore, the entire sliding surface 68B shown in Figure 5 may be curved toward the guide wall portion 25B, so that the entire sliding surface 68B forms a protrusion.

[0097] (B) In the above embodiment, as shown in Figures 11 and 12, the main lock gears 60A, 60C rotate in the direction of arrow S due to the force input from the cam 50 via the wedge member 80, but the rotation direction (inclination) of the main lock gears 60A, 60C is not limited to this. Depending on the shape and size of the wedge member and cam protrusion, movement in the opposite direction may occur, i.e., the lock may be completed when the engaging protrusion 64 of the lock gears 60A, 60C first meets the protrusion 55 of the cam 50 and the wedge member 80 engages with the cam 50.

[0098] (C) In the above embodiment, the multiple lock gears include four lock gears 60A to 60D, and the pair of main lock gears 60A, 60C that face each other in the radial direction include wedge members 80. However, the present invention is not limited to this. In the present invention, it is sufficient that at least one of the multiple lock gears includes a wedge member.

[0099] (D) In ​​the above embodiment, the wedge member 80 has a generally triangular shape, but the present invention is not limited to this. As shown in FIG. 8 , the wedge member 80 has a cam abutment surface 80a that contacts the pressing surface of the cam 50 (the outer peripheral surface 52a of the engagement protrusion 52), and various shapes can be used as long as the shape allows it to be sandwiched between the pressed surface 67 and the guide wall portion 25A. Therefore, the wedge member of the present invention may be not only triangular, but also trapezoidal or generally pentagonal in shape. Even with wedge members of these shapes, it is possible to move the main lock gears 60A, 60C radially outward without wobbling while pressing them against the guide wall portion 25B.

[0100] (E) In the above embodiment, the guide bracket 20 is fixed to the frame 2a of the seat cushion 2, and the internal gear 30 is fixed to the frame 3a of the seat back 3. However, the present invention is not limited to this, and the guide bracket 20 and the internal gear 30 may be arranged in an interchangeable manner. In other words, the internal gear 30 may be fixed to the frame 2a of the seat cushion 2, and the guide bracket 20 may be fixed to the frame 3a of the seat back 3.

[0101] <Summary of the embodiment> The above embodiment can be summarized as follows.

[0102] The reclining device of this embodiment includes a guide bracket fixed to one of the seat cushion and the seat back, an internal gear fixed to the other of the seat cushion and the seat back at a position opposite to the guide bracket, rotatable relative to the guide bracket and having a plurality of internal teeth, and a plurality of lock gears each having a plurality of external teeth that can mesh with some of the internal teeth of the internal gear, the lock gears being spaced apart in the circumferential direction of the internal gear and movable in the radial direction of the guide bracket between an engagement position where the external teeth and the internal teeth mesh with each other and a release position where the meshing is released, and a lock gear that rotates to move the plurality of lock gears radially from the release position to the engagement position. a lock spring that rotates the cam in a direction in which the plurality of lock gears move toward the meshing position; and a wedge member that presses at least one of the plurality of lock gears by receiving a pressing force from the cam in the radially outward direction, wherein the guide bracket has a plurality of pairs of opposing guide wall portions that guide the plurality of lock gears in the radial direction, the wedge member is interposed between one of the guide wall portions and the lock gear and presses the lock gear by receiving a pressing force from the cam, the lock gear is pushed outward in the radial direction while tilting by the cam, and the cam presses both the lock gear and the wedge member when locked, i.e., at the meshing position of the lock gear.

[0103] With this configuration, when the cam moves the lock gear from the release position to the engagement position, the lock gear, at a position immediately before the engagement position, can contact the cam by tilting the lock gear radially away from the wedge member due to the force of the cam pressing the lock gear via the wedge member, causing some of the external teeth of the lock gear to mesh with the internal teeth of the internal gear. This prevents the cam from contacting the lock gear before the wedge member, and ensures that the wedge member can reliably prevent the lock gear from rattling. Note that depending on the shape and size of the wedge member and the cam protrusion, the lock gear may be locked while tilted in the opposite direction to the above.

[0104] When the lock gear reaches the meshing position, the cam presses both the lock gear and the wedge member, so that the lock strength can be maintained even if a large rotational force acts on the reclining device.

[0105] Therefore, in the above-described reclining device, it is possible to maintain the lock strength in the locked state and to reliably suppress rattle of the lock gear by the wedge member.

[0106] In the above-mentioned reclining device, it is preferable that the lock gear has a pair of sliding surfaces that slidably abut against the pair of guide wall portions that sandwich the lock gear, and that the sliding surface of the pair of sliding surfaces located on the opposite side from the wedge member has a protrusion that protrudes toward the opposing guide wall portion.

[0107] In this configuration, when the lock gear receives a pressing force from the wedge member, the sliding surface and the entire lock gear tend to tilt, with the protruding portion of the sliding surface located on the opposite side of the wedge member as a fulcrum, making it possible for the cam to reliably press the lock gear together with the wedge member.

[0108] In the above-described reclining device, the protrusion preferably has an outer surface including a curved surface that curves toward the opposing guide wall portion.

[0109] In this configuration, the protrusion tilts smoothly while the curved outer surface of the protrusion abuts against the guide wall portion, making it even easier for the lock gear to tilt.

[0110] In the above-described reclining device, it is preferable that the external teeth of the plurality of external teeth located outside the range including the width center of the lock gear and in two ranges including both width ends of the lock gear are formed so as to have gaps between them and the internal teeth. Specifically, it is preferable that the external teeth in the two ranges including both width ends of the lock gear are formed so that the centers of their pitch circles are shifted from the center of the internal gear.

[0111] With this configuration, even when the external teeth of the lock gear near the widthwise center are meshed with the internal teeth of the internal gear, it is possible to form gaps between the external teeth and the internal teeth in two ranges including both ends in the widthwise direction, and the lock gear can be reliably tilted at a position immediately before the meshing position.

[0112] In the above-mentioned reclining device, it is preferable that the wedge member has a pressing surface that presses the lock gear by receiving the pressing force of the cam, and the lock gear has a pressed surface that is pressed by the pressing surface of the wedge member and extends in a direction inclined relative to the radial direction, and that at least one of the pressing surface and the pressed surface has portions that protrude in directions opposite to each other.

[0113] In this configuration, the pressing surface of the wedge member and the pressed surface of the lock gear come into point contact, making it even easier for the lock gear to tilt at a position immediately before the meshing position.

[0114] In the above-described reclining device, it is preferable that the pressed surface includes a curved surface that is curved so as to protrude in a direction facing the pressing surface.

[0115] In this configuration, the curved surface of the pressed surface comes into contact with the pressing surface, making it even easier for the lock gear to tilt.

[0116] In the above-described reclining device, the plurality of lock gears are preferably composed of a pair of main lock gears facing each other and a pair of sub-lock gears facing each other and spaced 90 degrees circumferentially from the pair of main lock gears, and the wedge member is preferably interposed between each of the pair of main lock gears and the cam.

[0117] With this configuration, when the reclining device is locked, the pair of main lock gears can receive the pressing force of the cam directly and indirectly via the wedge member. This allows the main lock gear to maintain a tight meshing state with the internal gear while suppressing wobble. Meanwhile, even if a large rotational force acts on the reclining device and disengages the main lock gear, the sub-lock gear can maintain the locked state in place of the main lock gear.

[0118] The seat of this embodiment is characterized by comprising a seat cushion, a seat back arranged at the rear of the seat cushion and capable of tilting in the fore-and-aft direction of the seat, and the above-mentioned reclining device that fixes the seat back at any tilt angle.

[0119] A seat having such a configuration is equipped with the reclining device described above, so that it is possible to maintain lock strength in the locked state while reliably suppressing rattle of the lock gear with the wedge member.

Claims

1. A vehicle seat belt comprising: a guide bracket fixed to one of a seat cushion and a seat back; an internal gear fixed to the other of the seat cushion and the seat back at a position opposite the guide bracket, rotatable relative to the guide bracket, and having a plurality of internal teeth; a plurality of lock gears, each having a plurality of external teeth that can mesh with some of the internal teeth of the internal gear, the lock gears being spaced apart circumferentially around the internal gear and movable in the radial direction of the guide bracket between an engagement position where the external teeth and the internal teeth mesh with each other and a release position where the meshing is released; a cam that rotates to move the plurality of lock gears radially from the release position to the engagement position; a lock spring that rotationally biases the cam in a direction where the plurality of lock gears move toward the engagement position; and a wedge member that presses at least one of the plurality of lock gears by receiving a pressing force from the cam in the radially outward direction, The guide bracket has multiple pairs of opposing guide wall portions that guide the multiple lock gears in the radial direction; the wedge member is interposed between one of the guide wall portions and the lock gears and presses the lock gears by receiving the pressing force of the cam; the lock gears are pushed outward in the radial direction while tilting by the cam; and the cam presses both the lock gears and the wedge member at the meshing position of the lock gears.

2. A reclining device as described in claim 1, wherein the lock gear has a pair of sliding contact surfaces that respectively slidably contact the pair of guide wall sections that sandwich the lock gear, and the sliding contact surface of the pair that is located on the opposite side of the wedge member has a protrusion that protrudes toward the opposing guide wall section.

3. A reclining device according to claim 2, wherein the protrusion has an outer surface including a curved surface that curves toward the opposing guide wall portion.

4. A reclining device according to any one of claims 1 to 3, wherein the external teeth of the plurality of external teeth that are located outside the range including the widthwise center of the lock gear and in two ranges including both widthwise ends of the lock gear are formed so as to leave gaps between them and the internal teeth.

5. A reclining device as claimed in claim 4, wherein the centers of the pitch circles of the external teeth in two ranges including both ends of the lock gear in the width direction are offset from the center of the internal gear so as to form a gap between the external teeth and the internal teeth.

6. A reclining device according to any one of claims 1 to 5, wherein the wedge member has a pressing surface that presses the lock gear by receiving the pressing force of the cam, and the lock gear has a pressed surface that is pressed by the pressing surface of the wedge member and extends in a direction inclined relative to the radial direction, and at least one of the pressing surface and the pressed surface has portions that protrude in directions opposite to each other.

7. A reclining device according to claim 6, wherein the pressed surface includes a curved surface that protrudes in a direction opposite to the pressing surface.

8. A reclining device according to any one of claims 1 to 7, wherein the plurality of lock gears are comprised of a pair of main lock gears facing each other and a pair of sub-lock gears facing each other and spaced 90 degrees apart in the circumferential direction from the pair of main lock gears, and the wedge member is interposed between each of the pair of main lock gears and the cam.

9. A seat comprising: a seat cushion; a seat back disposed at the rear of the seat cushion and tiltable in the front-to-rear direction of the seat; and a reclining device according to any one of claims 1 to 8 that fixes the seat back at an arbitrary tilt angle.

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