Patent Publication Number: US-2022219579-A1

Title: Seat reclining device for vehicle

Description:
TECHNICAL FIELD 
     The present invention relates to a seat reclining device for a vehicle. Specifically, the present invention relates to a vehicle seat reclining device for adjusting an inclination angle of a seat back. 
     BACKGROUND ART 
     In the related art, there is known a vehicle seat reclining device including a stepped lock mechanism capable of adjusting a backrest angle of a seat back by a constant pitch angle (Patent Literature 1). The vehicle seat reclining device is a joint device that couples the seat back to a seat cushion such that the backrest angle is adjustable. Specifically, the vehicle seat reclining device includes a ratchet and a guide that are constituted by substantially disk-shaped metal members assembled to be rotatable relative to each other, and a lock mechanism that locks the relative rotation between the ratchet and the guide. 
     The lock mechanism is configured such that a plurality of pawls set on the guide are biased and thereby pressed against and meshed with inner circumferential teeth formed on an outer circumferential portion of the ratchet, thereby locking the relative rotation between the ratchet and the guide. Each of the pawls is supported by the guide from both sides in a rotation direction and is guided to be movable only inward and outward in a radial direction. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: WO 2016/129423 
     SUMMARY OF INVENTION 
     Technical Problem 
     In order to ensure a sliding performance of each pawl, it is necessary to set a slight gap in the rotation direction between each pawl and each guide wall of the guide that supports the pawl from both sides in the rotation direction. However, when the gap is large, a posture of each pawl may be unstable (that is, so-called “rattling” occurs) due to inclination of each pawl between the guide walls. One object of the present invention is to provide a vehicle seat reclining device capable of ensuring a sliding performance of a pawl and preventing rattling at the same time. 
     Solution to Problem 
     [1] In a first aspect of the present invention, a vehicle seat reclining device includes: 
     a ratchet and a guide assembled in an axial direction to be rotatable relative to each other; 
     a pawl supported from both sides in a rotation direction by a pair of guide walls provided on the guide, and configured to be meshed with the ratchet due to movement in which the pawl is pressed outward in a radial direction, so as to restrict the relative rotation between the ratchet and the guide; and 
     a cam configured to press and move the pawl outward from an inner side in the radial direction, wherein 
     the pawl has an eccentric structure in which the pawl is pressed and inclined to one side in the rotation direction between the pair of guide walls due to a pressing force received from the cam, and has a first protrusion that projects from a side surface of the pawl on the one side in the rotation direction and restricts the inclination of the pawl by contact with the guide wall that the first protrusion faces. 
     According to the first aspect, although a gap in the rotation direction is provided between the pawl and each guide wall, the inclination of the pawl in the gap can be restricted by the contact between the first protrusion and the guide wall. Therefore, the sliding performance of the pawl can be ensured and the rattling can be prevented at the same time. 
     [2] In a second aspect of the present invention according to the first aspect, the pawl has a second protrusion that projects from a side surface of the pawl on the other side in the rotation direction and holds, by contact with the guide wall that the second protrusion faces, the pawl in a posture in which the pawl is in contact with both of the pair of guide walls. 
     According to the second aspect, the pawl can be abutted against both of the guide walls and held in a state in which the gap in the rotation direction is eliminated, and the rattling of the pawl can be eliminated more appropriately. 
     [3] In a third aspect of the present invention according to the second aspect, the second protrusion is located outward in the radial direction than the first protrusion. 
     According to the third aspect, the second protrusion can be abutted against the guide wall at a relatively early stage and restrict the inclination of the pawl when the pawl is inclined, with an abutting point between the first protrusion and the guide wall as a base point, in a direction to close the gap between the guide wall and the other side surface of the pawl on an outer circumferential side close to the meshing portion with the ratchet. 
     [4] In a fourth aspect of the present invention according to the second aspect or the third aspect, 
     the pawl has a main body surface portion that receives, from the inner side in the radial direction, the pressing force from the cam, and an offset surface portion that has a shape of being extruded from the main body surface portion into a half-punched shape in the axial direction and is disposed adjacently with the cam in the axial direction, and 
     the second protrusion has a shape in which a slope of the second protrusion extends over at least an entire area of the main body surface portion on the side surface of the pawl on the other side in the rotation direction. 
     According to the fourth aspect, structural strength of the second protrusion can be increased as compared with a configuration in which the second protrusion is partially formed on the other side surface of the pawl in the rotation direction. Further, the second protrusion can be simply shaped. 
     [5] In a fifth aspect of the present invention according to any one of the first aspect to the fourth aspect, 
     a plurality of pawls are provided, and 
     the first protrusion is formed on a specific pawl among the plurality of pawls. 
     According to the fifth aspect, the rattling of the pawls can be reasonably prevented. 
     [6] In a sixth aspect of the present invention according to any one of the first aspect to the fifth aspect, 
     the pawl has a main body surface portion that receives, from the inner side in the radial direction, the pressing force from the cam, and an offset surface portion that has a shape of being extruded from the main body surface portion into a half-punched shape in the axial direction and is disposed adjacently with the cam in the axial direction, and 
     the first protrusion has a shape in which a slope of the first protrusion extends over at least an entire area of the main body surface portion on the side surface of the pawl on the one side in the rotation direction. 
     According to the sixth aspect, structural strength of the first protrusion can be increased as compared with a. configuration in which the first protrusion is partially formed on the one side surface of the pawl in the rotation direction. Further, the first protrusion can be simply shaped. 
     [7] In a seventh aspect of the present invention, a vehicle seat reclining device includes: 
     a ratchet and a guide assembled in an axial direction to be rotatable relative to each other; 
     a pawl supported from both sides in a rotation direction by a pair of guide walls provided on the guide, and configured to be meshed with the ratchet due to movement in which the pawl is pressed outward in a radial direction, so as to restrict the relative rotation between the ratchet and the guide; 
     a cam configured to press and move the pawl outward from an inner side in the radial direction; 
     an eccentric structure in which the pawl is pressed and inclined to one side in the rotation direction between the pair of guide walls due to a pressing force received from the cam; and 
     a first protrusion configured to project from the guide wall that faces a side surface of the pawl on the one side in the rotation direction and restrict the inclination of the pawl by contact with the pawl. 
     According to the seventh aspect, although a gap in the rotation direction is provided between the pawl and each guide wall, the inclination of the pawl in the gap can be restricted by the contact between the first protrusion and the pawl. Therefore, the sliding performance of the pawl can be ensured and the rattling can be prevented at the same time. 
     [8] In an eighth aspect of the present invention according to the seventh aspect, the vehicle seat reclining device further includes a second protrusion configured to project from the guide wall that faces a side surface of the pawl on the other side in the rotation direction and restrict the inclination of the pawl by contact with the pawl, so as to hold the pawl in a posture in which the pawl is in contact with both of the pair of guide walls. 
     According to the eighth aspect, the pawl can be abutted against both of the guide walls and held in a state in which the gap in the rotation direction is eliminated, and the rattling of the pawl can be prevented more appropriately. 
     [9] In a ninth aspect of the present invention according to the eighth aspect, 
     the second protrusion has a shape in which a slope of the second protrusion extends over an entire area of a side surface of the guide wall that faces the pawl. 
     According to the ninth aspect, structural strength of the second protrusion can be increased as compared with a configuration in which the second protrusion is partially formed on the guide wall. Further, the second protrusion can be simply shaped. 
     [10] In a tenth aspect of the present invention according to any one of the seventh aspect to the ninth aspect, 
     the first protrusion has a shape in which a slope of the first protrusion extends over an entire area of a side surface of the guide wall that faces the pawl. 
     According to the tenth aspect, structural strength of the first protrusion can be increased as compared with a configuration in which the first protrusion is partially formed on the guide wall. Further, the first protrusion can be simply shaped. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a schematic configuration of a vehicle seat to which a vehicle seat reclining device according to a first embodiment is applied. 
         FIG. 2  is an exploded perspective view showing a main part of  FIG. 1 . 
         FIG. 3  is an exploded perspective view as viewed from a side opposite to that of  FIG. 2 . 
         FIG. 4  is an exploded perspective view of the vehicle seat reclining device. 
         FIG. 5  is an exploded perspective view as viewed from a side opposite to that of  FIG. 4 . 
         FIG. 6  is an outer side view of the vehicle seat reclining device. 
         FIG. 7  is an inner side view of the vehicle seat reclining device. 
         FIG. 8  is a front side view of the vehicle seat reclining device. 
         FIG. 9  is a cross-sectional view taken along a line IX-IX in  FIG. 1 . 
         FIG. 10  is a cross-sectional view taken along a line X-X of  FIG. 8  and showing a locked state of the vehicle seat reclining device. 
         FIG. 11  is a cross-sectional view corresponding to  FIG. 10  and showing an unlocked state of the vehicle seat reclining device. 
         FIG. 12  is a cross-sectional view showing a state in which a ratchet is rotated from  FIG. 11  to a free region. 
         FIG. 13  is a cross-sectional view showing a state in which a locking operation of the vehicle seat reclining device is blocked from  FIG. 12 . 
         FIG. 14  is a cross-sectional view showing a state in which the ratchet is rotated to a start position of a lock region. 
         FIG. 15  is an enlarged view of a part XV in  FIG. 9 . 
         FIG. 16  is a cross-sectional view showing a state in which a rotation cam is biased and thereby pressed against a guide wall. 
         FIGS. 17A to 17D  are cross-sectional views showing different cases of a change in the locking operation of each pawl caused by a change in a rotation position of the ratchet. 
         FIGS. 18A to 18D  are schematic diagrams each showing a positional relation between an abutting protrusion of each pawl and a projecting portion of the ratchet in each of  FIGS. 17A to 17D . 
         FIG. 19  is an outer side view of the pawls. 
         FIG. 20  is an inner side view of the pawls. 
         FIG. 21  is a side view showing an angle adjustment range of a seat back. 
         FIG. 22  is an inner side view showing a state of the vehicle seat reclining device in  FIG. 21 . 
         FIG. 23  is a cross-sectional view taken along a line XXIII-XXIII of  FIG. 22 . 
         FIG. 24  is a cross-sectional view taken along a line XXIV-XXIV of  FIG. 22 . 
         FIG. 25  is a side view showing a state in which the seat back is tilted rearward from a torso angle. 
         FIG. 26  is an inner side view showing a state of the vehicle seat reclining device in  FIG. 25 . 
         FIG. 27  is a cross-sectional view taken along a line XXVII-XXVII of  FIG. 26 . 
         FIG. 28  is a cross-sectional view taken along a line XXVIII-XXVIII of  FIG. 26 . 
         FIG. 29  is a side view showing a state in which the seat back is tilted forward from the torso angle. 
         FIG. 30  is an inner side view showing a state of the vehicle seat reclining device in  FIG. 29 . 
         FIG. 31  is a cross-sectional view taken along a line XXXI-XXXI of  FIG. 30 . 
         FIG. 32  is a cross-sectional view taken along a line XXXII-XXXII of  FIG. 30 . 
         FIG. 33  is an enlarged view of a portion XXXIII in  FIG. 14 . 
         FIG. 34  is an enlarged view of a portion XXXIV of  FIG. 10  showing an enlarged meshing state of a specific pawl with respect to the ratchet. 
         FIG. 35  is a cross-sectional view corresponding to  FIG. 34  and showing a meshing state in which a first protrusion is abutted against the guide wall. 
         FIG. 36  is a cross-sectional view showing a state in which the ratchet is rotated in a. shown clockwise direction from  FIG. 35  to a position at which a second protrusion is abutted against the guide wall. 
         FIG. 37  is a cross-sectional view corresponding to  FIG. 34  and showing a configuration of a vehicle seat reclining device according to a second embodiment. 
         FIG. 38  is a cross-sectional view corresponding to  FIG. 34  and showing a configuration of a vehicle seat reclining device according to a third embodiment. 
         FIG. 39  is a cross-sectional view corresponding to  FIG. 34  and showing a configuration of a vehicle seat reclining device according to a fourth embodiment. 
         FIG. 40  is a cross-sectional view corresponding to  FIG. 34  and showing a configuration of a vehicle seat reclining device according to a fifth embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention will be described below with reference to the drawings. 
     First Embodiment 
     Schematic Configuration of Seat Reclining Device  4  (Vehicle Seat Reclining Device) 
     First, a configuration of a seat reclining device  4  according to a first embodiment of the present invention will be described with reference to  FIGS. 1 to 36 . In the following description, directions such as front, rear, upper, lower, left, and right directions, indicate the directions shown in the drawings. Further, a “seat width direction” indicates a left-right direction of a seat  1  to be described later. 
     As shown in  FIG. 1 , the seat reclining device  4  of the present embodiment is applied to the seat  1  constituting a right seat of an automobile. The seat reclining device  4  is configured as a reclining adjustment mechanism that couples a seat back  2  constituting a backrest portion of the seat I to a seat cushion  3  constituting a seating portion, in a state in which a backrest angle is adjustable. Specifically, a pair of left and right seat reclining devices  4  are provided between the seat back  2  and the seat cushion  3 . The seat reclining devices  4  are configured to fix and release the backrest angle of the seat back  2  by being switched at the same time to locked and unlocked states. 
     Specifically, as shown in  FIGS. 2 and 3 , the seat reclining devices  4  are respectively interposed between lower end portions of side frames  2 F constituting left and right side frameworks of the seat back  2  and reclining plates  3 F coupled to rear end portions of left and right side frameworks of the seat cushion  3 . The reclining plates  3 F are located outward of the lower end portions of the side frames  2 F in the seat width direction. The seat reclining devices  4  are coupled in a state of being coaxially rotatable relative to each other or prevented from rotating. 
     As shown in  FIG. 1 , the seat reclining devices  4  are normally held in the locked state in which the backrest angle of the seat hack  2  is fixed. The seat reclining devices  4  are released from the locked state at the same time by an operation (Arrow A of  FIG. 1 ) of a user pulling up a reclining lever  5  provided on a side portion on a vehicle outer side (right side) of the seat cushion  3 . Accordingly, the seat reclining devices  4  are switched to the unlocked state in which the backrest angle of the seat back  2  is adjustable in a seat front-rear direction. When the operation of the reclining lever  5  is returned, the seat reclining devices  4  are biased and returned to the locked state again. 
     Return springs  6  for applying spring biasing forces in a direction in which the seat back  2  is tilted forward and rotated are respectively hooked between the left and right side frames  2 F of the seat back  2  and the reclining plates  3 F located outward of the side frames  2 F. When the fixed state of the backrest angle fixed by the seat reclining devices  4  is released, the seat back  2  is raised to a position, at which the seat back  2  is abutted with a back of a seated occupant, due to the rotational biasing forces of the return springs  6 . 
     Then, the backrest angle of the seat back  2  is freely adjusted hack and forth according to movement (Arrow B in  FIG. 1 ) in which the back of the seated occupant is tilted back and forth. Thus, the backrest angle of the seat back  2  can be easily adjusted by providing the return springs  6  for applying biasing forces in a forward rotation direction to the seat back  2 . Specifically, as shown in  FIG. 21 , the seat back  2  can be rotated in a seat front-rear direction in a rotation region of about 180 degrees between a forward tilt position Pa at which the seat back  2  is folded on an upper surface of the seat cushion  3  and a rearward tilt position Pc at which the seat hack  2  is tilted rearward substantially horizontally. 
     A structure for locking the seat back  2  to the forward tilt position Pa is a structure in which locking plates  2 Fc, which are coupled to outer surface portions of the side frames  2 F of the seat back  2  are abutted against and locked to front stoppers  3 Fc which are formed by projecting from front edge portions of the reclining plates  3 F. A structure for locking the seat back  2  to the rearward tilt position Pc is a structure in which the locking plates  2 Fc, which are coupled to the outer surface portions of the side frames  2 F of the seat hack  2 , are abutted against and locked to rear stoppers  3 Fd which are formed by projecting from rear edge portions of the reclining plates  3 F. 
     Here, in the rotation region of the seat back  2 , a rotation region in which the backrest angle of the seat back  2  is changed by about 90 degrees from an initial lock position Pb at which the seat back  2  stands up substantially vertically to the rearward tilt position Pc is set as a “lock region A 1 ” in which the backrest angle of the seat back  2  is returned to the fixed state by releasing the operation of pulling up the reclining lever  5 . Further, a rotation region in which the backrest angle of the seat back  2  is changed by about 90 degrees from the initial lock position Pb to the forward tilt position Pa is set as a “free region A 2 ”, in which the angle of the seat back  2  is not fixed but maintained in a released state (a state in which the lock is disabled) even when the operation of pulling up the reclining lever  5  is released. 
     The lock region A 1  and the free region A 2  are set by to-be-described functions of the seat reclining devices  4 . By setting the free region A 2 , when the reclining lever  5  is operated and the seat back  2  is tilted forward to a position where the seat back  2  enters the free region A 2  in a state in which no person is seated in the seat  1 , the seat back  2  is naturally tilted to the forward tilt position Pa even when the operation of the reclining lever  5  is not continued. 
     Specifically, as shown in  FIGS. 2 and 3 , the seat reclining device  4  includes a ratchet  10  (see  FIG. 2 ) integrally coupled to the outer surface portion of the side frame  2 F on each side of the seat back  2 , and a guide  20  (see  FIG. 3 ) integrally coupled to an inner surface portion of the reclining plate  3 F on each side. The seat reclining devices  4  are configured to fix and release the backrest angle of the seat back  2  by being switched to lock and release the relative rotation between the ratchet  10  and the guide  20 . 
     Configurations of Components of Seat Reclining Device  4   
     Hereinafter, configurations of components of the pair of left and right seat reclining devices  4  will be described in detail. The seat reclining devices  4  are bilaterally symmetrical to each other and have the same configuration. Therefore, hereinafter, as an example, a configuration of the seat reclining device  4  disposed on the vehicle outer side (right side) shown in  FIGS. 2 and 3  will be described in detail. 
     As shown in  FIGS. 4 and 5 , the seat reclining device  4  includes the substantially circular plate-shaped ratchet  10  and guide  20  which are assembled to each other in an axial direction, three pawls  30  assembled between the ratchet  10  and the guide  20 , and a rotation cam  40  that moves the pawls  30  inward and outward in a radial direction. Further, the seat reclining device  4  includes a lock spring  50  (spiral spring) that biases the rotation cam  40  relative to the guide  20  in a lock rotation direction, and a substantially cylindrical outer circumferential ring  60  that is mounted across outer circumferential portions of the ratchet  10  and the guide  20 , 
     The outer circumferential ring  60  functions as a holding member that holds the ratchet  10  and the guide  20  in a state of being assembled to each other in the axial direction. Here, the rotation cam  40  corresponds to a “cam” of the present invention. Each of the ratchet  10 , the guide  20 , the three pawls  30 , and the rotation cam  40  is hardened by quenching processing after press shaping and has high structural strength. 
     Ratchet  10   
     As shown in  FIG. 4 , the ratchet  10  is formed by cutting one metal plate member into a substantially disk shape and extruding the substantially disk-shaped plate member into a half-punched shape in a plate thickness direction (axial direction) at some positions. Specifically, the ratchet  10  is configured to be formed such that a stepped cylindrical portion projecting in two stages into a stepped cylindrical shape in the axial direction, which is the assembling direction of the ratchet  10  to the guide  20 , is extruded in a half-punched shape and formed on an outer circumferential edge portion of a disk main body  11  of the ratchet  10 . 
     A cylindrical part on an outer circumferential side of the stepped cylindrical portion is formed as a cylindrical portion  12  whose entire inner circumferential surface is formed with inner teeth  12 A. A cylindrical part on an inner circumferential side is formed as an intermediate cylindrical portion  13  having a projecting length in the axial direction shorter than that of the cylindrical portion.  12 . The inner teeth  12 A of the cylindrical portion  12  is set to a tooth surface shape with which to-be-described outer teeth  31  formed on outer circumferential surface portions of the pawls  30  can be meshed with the inner teeth  12 A from an inner side in the radial direction, Specifically, the inner teeth  12 A have a shape in which tooth surfaces are arranged at equal intervals at a pitch of two degrees in the rotation direction. 
     On an inner circumferential surface of the intermediate cylindrical portion  13 , three regions (a first region  13 A, a second region  13 B, and a third region  13 C) in which an inner diameter dimension from a rotation center C of the ratchet  10  or a length in the rotation direction are set individually, and a first projection portion  13 D and a second projection portion  13 E which project inward in the radial direction from boundaries between these regions are formed. 
     Each of the first region  13 A, the second region  13 B, and the third region  13 C is formed to have an inner circumferential surface shape curving in an arc shape drawn around the rotation center C of the ratchet  10 . Specifically, as shown in  FIG. 10 , the first region  13 A and the third region  13 C have an inner circumferential surface shape of the same inner diameter dimension slightly larger than that of the second region  13 B. 
     As shown in  FIGS. 10, 17A, and 18A , when the ratchet  10  is at a rotation angle at which the first region  13 A overlaps in the rotation direction with a to-be-described main pawl P 1  that is one of the three pawls  30 , the first region  13 A is the lock region A 1  in which the main pawl P 1  is allowed to mesh with the inner teeth  12 A. At this time, the second region  13 B and the third region  13 C are disposed to overlap with the remaining two sub-pawls P 2  in the rotation direction and are set as relief regions A 3  in which the sub-pawls P 2  are allowed to mesh with the inner teeth  12 A. Here, the main pawl P 1  corresponds to a “specific pawl” of the present invention. 
     Meanwhile, when the ratchet  10  is at a rotation angle at which the second region  13 B overlaps with the main pawl P 1  in the rotation direction as shown in  FIG. 12 , the second region  13 B is the free region A 2  in which the main pawl P 1  rides on the inner circumferential surface and the meshing thereof with the inner teeth  12 A is blocked, as shown in  FIGS. 13, 17B, and 18B . At this time, the third region  13 C and the first region  13 A are disposed to overlap with the remaining two sub-pawls P 2  in the rotation direction and are set as relief regions A 3  in which movement of the sub-pawls P 2  are allowed to escape. 
     That is, the intermediate cylindrical portion  13  of the ratchet  10  is configured to allow the locking operation of the main pawl P 1  in the first region  13 A as shown in  FIG. 10 , and block the locking operation of the main pawl P 1  in the second region  13 B as shown in  FIGS. 12 and 13 . As shown in  FIG. 10 , when the locking operation of the main pawl P 1  among the pawls  30  is allowed, the locking operation of the remaining two sub-pawls P 2  is also allowed. As shown in  FIGS. 12 and 13 , when the locking operation of the main pawl P 1  among the pawls  30  is blocked, the locking operation of the remaining two sub-pawls P 2  is also blocked. 
     In this way, the intermediate cylindrical portion  13  of the ratchet  10  controls allowance and prevention of the locking operation of the main pawl P 1  by the first region  13 A and the second region  13 B. When the first region  13 A functions as the lock region A 1  (see  FIG. 10 ), the other two regions (second region  13 B, third region  13 C) function as the relief regions A 3  in which the locking operation of the remaining two sub-pawls P 2  is allowed. Further, when the second region  13 B functions as the free region A 2  (see  FIG. 13 ), the other two regions (first region  13 A, third region  13 C) function as the relief regions A 3  in which the movement of the remaining two sub-pawls P 2  is released. 
     As shown in  FIGS. 17C and 18C , when the main pawl P 1  moves from the lock region A 1  (first region  13 A) to the free region A 2  (second region  13 B) due to the rotation of the ratchet  10 , the main pawl P 1  may be abutted against a step between the first region  13 A and the second region  13 B in the rotation direction in a state in which the main pawl P 1  is halfway pushed outward in the radial direction. The first projection portion  13 D and the second projection portion  13 E are respectively formed at positions at which the sub-pawls P 2  are abutted against the first projection portion  13 D and the second projection portion  13 E in the rotation direction at the same time in the above case. Due to the abutment of the sub-pawls P 2  at the same time, a load that the main pawl P 1  receives when being abutted against the step can also be distributed to the other two sub-pawls P 2 . 
     Specifically, the first projection portion  13 D and the second projection portion  13 E are formed at positions at which, when an abutting protrusion  34  of the main pawl P 1  is abutted against the step between the first region  13 A and the second region  13 B in the rotation direction due to the rotation of the ratchet  10 , abutting protrusions  34  of the remaining two sub-pawls P 2  are abutted against the first projection portion  13 D and the second projection portion  13 E in the same rotation direction at the same time. Configurations of the abutting protrusions  34  will be described in detail later. 
     As shown in  FIGS. 14, 17D, and 18D , the second projection portion  13 E is formed to protrude on a starting side in the rotation direction of the lock region A 1  (first region  13 A), that is, an end portion of the lock region A 1  on a side opposite to a side adjacent to the free region A 2  (second region  13 B). The second projection portion  13 E is formed at a position at which the second projection portion  13 E can overlap with the abutting protrusion  34  of the main pawl P 1  in the rotation direction as shown in  FIGS. 14, 17D, and 18D  when the seat back  2  is tilted to a starting end of the lock region A 1 , that is, the rearward tilt position Pc as shown in  FIG. 21 . 
     The reason is as follows. That is, as shown in  FIG. 21 , when the seat back  2  is tilted to the rearward tilt position Pc, the locking plate  2 Fc is abutted against and locked to the rear stopper  3 Fd of the reclining plate  3 F. At this time, when the abutting protrusion  34  of the main pawl P 1  shown in  FIG. 14  is abutted, against the second projection portion  13 E in the rotation direction before the locking plate  2 Fc is abutted against the rear stopper  3 Fd of the reclining plate  3 F due to the fitting of the seat reclining device  4  and peripheral components thereof, a large load is applied to the seat reclining device  4 . Therefore, in order to prevent such a situation, the second projection portion  13 E is formed with a relief recess portion  13 E 1  that releases the abutment of the abutting protrusion  34  of the main pawl P 1  against the second projection portion  13 E in the rotation direction. 
     As shown in  FIG. 33 , the relief recess portion  13 E 1  is formed in a shape in which a corner portion of the second projection portion  13 E on a shown clockwise direction side is thinned into a substantially rectangular shape. When the seat back  2  is tilted to the rearward tilt position Pc and the locking plate  2 Fc is abutted against and locked to the rear stopper  3 Fd of the reclining plate  3 F as shown in  FIG. 21 , due to dimensional variation of the fitting, even when the abutting protrusion  34  of the main pawl P 1  overlaps with the second projection portion  13 E in the rotation direction as shown in  FIG. 33 , the relief recess portion  13 E 1  receives the abutting protrusion  34  such that the abutting protrusion  34  is not abutted against the second projection portion  13 E in the rotation direction, Specifically, the relief recess portion  13 E 1  receives the abutting protrusion  34  in a state in which there is a gap Y in the rotation direction between the relief recess portion  13 E 1  and a side surface of the abutting protrusion  34  on a shown counterclockwise direction side. 
     When the abutting protrusion  34  of the main pawl P 1  that enters the relief recess portion  13 E 1  is pushed outward in the radial direction, the abutting protrusion  34  rides on an inner circumferential surface of the relief recess portion  13 E 1 , and the main pawl P 1  is prevented from meshing with the inner teeth  12 A of the ratchet  10 . As a result, the main pawl P 1  is prevented from being locked at a position (a rotation position beyond the lock region A 1 ) at which the abutting protrusion  34  of the main pawl P 1  enters the relief recess portion  13 E 1 . 
     As shown in  FIGS. 4 and 5 , a through hole  11 A penetrating in a round hole shape is formed at a central portion (a position at the rotation center C) of the disk main body  11  of the ratchet  10 . In the through hole  11 A, an operation pin  5 A inserted into a central portion (a position at the rotation center C) of the rotation cam  40  to be described later is inserted in a freely rotatable state from the outside in the axial direction. 
     As shown in  FIG. 3 , the ratchet  10  is set such that an outer surface of the disk main body  11  is in surface contact with an outer surface of the side frame  2 F of the seat back  2  and the ratchet  10  is integrally coupled to the side frame  2 F of the seat back  2  by welding contact portions therebetween. Specifically, the ratchet  10  is set in a state in which three dowels  14  formed to project on the outer surface of the disk main body  11  of the ratchet  10  are fitted into three corresponding fitting holes  2 Fa formed in the side frame  2 F of the seat back  2 , and the outer surface of the disk main body  11  is in surface contact with the outer surface of the side frame  2 F. 
     Then, the ratchet  10  is coupled to the side frame  2 F by laser-welding peripheral regions (coupling regions A 4 ) of the fitted portions to the side frame  2 F. As shown in  FIG. 5 , the dowels  14  are formed respectively in regions in the rotation direction in which the first region  13 A, the second region  13 B, and the third region  13 C of the intermediate cylindrical portion  13  are located. Each of the dowels  14  is formed to curve in an arc shape around the rotation center C of the ratchet  10 . 
     Regions on a radially outer side of the dowels  14  on the outer surface of the disk main body  11  of the ratchet  10  are defined as the coupling regions A 4  in which the outer surface of the disk main body  11  is abutted against and laser-welded to the side frame  2 F in a surface contact state. As shown in  FIG. 7 , the coupling regions A 4  are configured such that, due to the projection-recess shape of the intermediate cylindrical portion  13  formed on outer circumferential edge portions of the coupling regions A 4 , the coupling regions  4 A at positions at which the first region  13 A and the third region  13 C are located each have an expanded surface portion  11 B whose dimension in the radial direction is expanded from the coupling region A 4  at a position at which the second region  13 B is located. 
     That is, as described above, the first region  13 A and the third region  13 C formed on the intermediate cylindrical portion  13  are formed to have a shape expanded outward in the radial direction from the second region  13 B. Therefore, the coupling regions  4 A at the positions at which the first region  13 A and the third region  13 C are formed each are configured to expand in dimension in the radial direction as compared with the coupling region A 4  at the position at which the second region  13 B is formed. According to the above configuration, the outer surface of the disk main body  11  of the ratchet  10  is firmly welded to the side frame  2 F in a state in which the two coupling regions A 4  each having the expanded surface portion  11 B, which are at the positions at which the first region  13 A and the third region  13 C are formed, are abutted against the side frame  2 F more widely to the outer side in the radial direction. 
     The welding of the ratchet  10  to the side frame  2 F is performed such that welding beads are placed to enclose each dowel  14  in a C shape spanning from a radially outer side to both the side regions in the rotation direction. As shown in  FIG. 3 , a round hole-shaped penetrating hole  2 Fb penetrating the side frame  2 F is formed in the side frame  2 F at a position at which the penetrating hole  2 Fb faces the through hole  11 A, which is formed in the central portion (position at the rotation center C) of the ratchet  10 , in the axial direction. The operation pin  5 A inserted through the through hole  11 A of the ratchet  10  is inserted through the penetrating hole  2 Fb in the axial direction. 
     Guide  20   
     As shown in  FIG. 5 , the guide  20  is formed by cutting a metal plate-shaped member into a substantially disk shape having an outer diameter slightly larger than that of the ratchet  10  and extruding the substantially disk-shaped plate member into a half-punched shape in a plate thickness direction (axial direction) at some portions. Specifically, the guide  20  is configured such that a cylindrical portion  22  projecting into a cylindrical shape in the axial direction, which is the assembling direction of the guide  20  to the ratchet  10 , is extruded into a half-punched shape and formed on an outer circumferential edge portion of a disk main body  21  of the guide  20 . 
     The cylindrical portion  22  is formed to have an inner diameter dimension slightly larger than an outer diameter dimension of the cylindrical portion  12  of the ratchet  10 . Specifically, the cylindrical portion  22  is configured such that a thickness thereof in the radial direction is formed to be smaller than a plate thickness of the outer circumferential ring  60  to be described later (see  FIG. 15 ). More specifically, the cylindrical portion  22  is configured such that the thickness thereof in the radial direction is thinned to an extend than an outer circumferential surface thereof is located inward in the radial direction than an outer circumferential surface of a stepped portion  63  of the outer circumferential ring  60  to be described later. As shown in  FIG. 9 , the guide  20  is set such that the cylindrical portion  12  of the ratchet  10  is loosely fitted into the cylindrical portion  22  in the axial direction. 
     Therefore, the guide  20  is assembled in a state in which the cylindrical portions  22 ,  12  are loosely fitted to each other on an inner side and an outer side in the radial direction between the guide  20  and the ratchet  10  and are supported from the inner side and the outer side to be rotatable relative to each other. Then, the outer circumferential ring  60  to be described later is mounted in a manner of crossing the cylindrical portion  22  of the guide  20  and the cylindrical portion  12  of the ratchet  10  from an outer circumferential side, and thereby the guide  20  is assembled to the ratchet  10  via the outer circumferential ring  60  in a state in which the guide  20  is prevented from coming off in the axial direction (see  FIGS. 2 to 3 and 6  to  9 ). 
     As shown in  FIG. 5 , guide walls  23  each projecting in a substantially fan shape in the axial direction, which is the assembling direction to the ratchet  10 , are extruded into a half-punched shape at three positions in the rotation direction and formed on an inner surface of the disk main body  21  of the guide  20 . The guide walls  23  have a shape in which outer circumferential surfaces thereof on an outer side in the radial direction are curved so as to draw an arc on the same circumference drawn around the rotation center C of the guide  20 . The guide walls  23  are set in a state of being loosely fitted into the cylindrical portion  12  of the ratchet  10  assembled inside the cylindrical portion  22  of the guide  20 . 
     Due to formation of the guide walls  23 , recess-shaped pawl accommodating grooves  24 A are formed in regions between the guide walls  23  in the rotation direction on an inner surface of the disk main body  21  of the guide  20 . In the pawl accommodating grooves  24 A, the three pawls  30 . which will be described later, can be set to slide only inward and outward in the radial direction. Further, a cam accommodating groove  2413  in which the rotation cam  40  to be described later can be set to be axially rotatable is formed in a central region on the inner surface of the disk main body  21  surrounded by the guide walls  23 . 
     As shown in  FIGS. 10 and 11 , the guide walls  23  support the corresponding pawl  30 . which is set in the pawl accommodating groove  24 A, from both sides in the rotation direction by regulating surfaces  23 A which are two side surfaces in the rotation direction that face the corresponding pawl accommodating groove  24 A. Accordingly, the guide walls  23  guide the corresponding pawl  30  from both sides in the rotation direction such that the pawl  30  slides only inward and outward in the radial direction. 
     Further, the guide walls  23  support the rotation cam  40 , which is set in the cam accommodating groove  24 B, from the outer side in the radial direction by support surfaces  23 B which are inner circumferential surfaces of the guide walls  23  in the radial direction that face the cam accommodating groove  24 B. Therefore, the guide walls  23  guide the rotation cam  40  from the outer side in the radial direction such that the rotation cam  40  is rotatable in a substantially central (rotation center C) position on the disk main body  21  of the guide  20 . 
     Further, a substantially round hole-shaped through hole  21 A, in which a lock spring  50  to be described later is set, passes in the axial direction through a central portion (a position at the rotation center C) of the disk main body  21  of the guide  20 . In the through hole  21 A, an elongated hooking hole  21 Aa extending outward in the radial direction is formed, An outer end portion  52  of the lock spring  50  set in the through hole  21 A is fitted into the hooking hole  21 Aa in the axial direction and is set in an integral state in the rotation direction. 
     As shown in  FIG. 2 , the guide  20  is set such that the outer surface of the disk main body  21  is in surface contact with the inner surface of the reclining plate  3 F, and the guide  20  is integrally coupled to the reclining plate  3 F by welding the contact portions between the guide  20  and the reclining plate  3 F. Specifically, the ratchet  20  is set in a state in which three dowels  21 B formed to project on the outer surface of the disk main body  21  of the guide  20  are fitted into three corresponding fitting holes  3 Fa formed in the reclining plate  3 F, and the outer surface of the disk main body  21  is in surface contact with the inner surface of the reclining plate  3 F. 
     Then, the guide  20  is coupled to the reclining plate  3 F by laser-welding peripheral regions of the fitted portions to the reclining plate  3 F. As shown in  FIG. 4 , the dowels  21 B are formed such that the dowels  21 B are extruded in the axial direction as floating islands in regions on a back side of the pawl accommodating grooves  24 A (see  FIG. 5 ) on the outer surface of the disk main body  21 . As shown in  FIG. 2 , a round hole-shaped penetrating hole  3 Fb penetrating the reclining plate  3 F is formed in the reclining plate  3 F at a position at which the penetrating hole  3 Fb faces the through hole  21 A, which is formed in the central portion (position at the rotation center C) of the guide  20 , in the axial direction. The operation pin  5 A inserted through the through hole  21 A of the guide  20  passes through the penetrating hole  3 Fb in the axial direction. 
     Pawl  30   
     As shown in  FIGS. 4 and 5 , each of the pawls  30  is formed by cutting one metal plate-shaped member into a substantially rectangular shape and extruding the substantially rectangular member into a half-punched shape in a plate thickness direction (axial direction) at some positions. Specifically, the pawl  30  has a shape in which an offset surface portion  30 B constituting a substantially half region of the pawl  30  on the inner side in the radial direction is extruded into a half-punched shape by a substantial plate thickness in the axial direction that is the assembling direction of the pawl  30  to the ratchet  10  relative to a main body surface portion  30 A constituting a substantially half region on the outer side in the radial direction. 
     The three pawls  30  have substantially the same shape, and one of the three pawls  30  serves as the main pawl P 1  having a function different from those of the other two sub-pawls P 2 . Specific configurations thereof will be described in detail below. Hereinafter, specific configurations of components common to the pawls  30  will be described first. 
     As shown in  FIGS. 10 and 11 , the pawls  30  are set in a state of being accommodated one by one in the pawl accommodating grooves  24 A formed on the inner surface of the disk main body  21  of the guide  20 . With such setting, each of the pawls  30  is surface-supported from both sides in the rotation direction by the regulating surfaces  23 A of the guide walls  23  facing the pawl accommodating groove  24 A from both sides in the rotation direction. As a result, each of the pawls  30  is supported to be only movable inward and outward in the radial direction along the regulating surfaces  23 A. 
     Specifically, as shown in  FIG. 9 , when the pawls  30  are set in the pawl accommodating grooves  24 A (see  FIG. 5 ), main body surface portions  30 A of the pawls  30  are abutted against the inner surface of the disk main body  21  of the guide  20 . Therefore, the inner teeth  12 A of the cylindrical portion  12  of the ratchet  10  set inside the cylindrical portion  22  of the guide  20  face the pawls  30  in the radial direction at positions on outer sides of the main body surface portions  30 A in the radial direction. The offset surface portions  30 B of the pawls  30  are set in a state of being separated in the axial direction from the inner surface of the disk main body  21  of the guide  20 , and are set in a state of overlapping with the intermediate cylindrical portion  13  of the ratchet  10  in the axial direction. 
     As shown in  FIG. 4 , outer teeth  31  whose tooth surfaces face outward in the radial direction are formed on an outer circumferential surface of the main body surface portion  30 A of each pawl  30  on an outer side in the radial direction so as to be arranged continuously over the entire region in the rotation direction. The outer circumferential surface of each pawl  30  on which the outer teeth  31  are formed has a projection curving surface shape along the inner circumferential surface shape of the cylindrical portion  12  on which the inner teeth  12 A of the ratchet  10  are formed. 
     Similarly to the inner teeth  12 A of the ratchet  10  that are meshed with the outer teeth  31 , the outer teeth  31  of each pawl  30  have a shape in which tooth surfaces are arranged at equal intervals at a pitch of two degrees in the rotation direction. With the above configuration, as shown in  FIG. 10 , the outer teeth  31  of the pawls  30  are pressed into the inner teeth  12 A of the ratchet  10  from the inner side in the radial direction, and thereby all the outer teeth  31  are meshed with the inner teeth  12 A. However, strictly, as shown in  FIG. 34 , the outer teeth  31  of each pawl  30  are configured such that the outer teeth  31  are meshed with the inner teeth  12 A of the ratchet  10  with a central tooth surface of the outer teeth  31  in the rotation direction enters the inner teeth  12 A most deeply, and a tooth height decrease from the center in the rotation direction toward both ends in the rotation direction such that an entering depth into the inner teeth  12 A gradually becomes shallower. 
     Thus, during meshing of the outer teeth  31  of each pawl  30  with the inner teeth  12 A of the ratchet  10 , even when the pawl  30  is pressed straight outward in the radial direction, the tooth surfaces of the outer teeth  31  is not all in contact with the tooth surfaces of the inner teeth  12 A, and the outer teeth  31  can be appropriately meshed with the inner teeth  12 A. That is, the outer teeth  31  of each pawl  30  are configured such that the central tooth surface faces a tooth surface straightly in a traveling direction of the meshing movement. 
     However, other tooth surfaces of the outer teeth  31  arranged from the central tooth surface toward both end sides in the rotation direction face tooth surfaces obliquely in the rotation direction relative to the tooth surface at the center. Therefore, when each pawl  30  is pushed outward in the radial direction, the central tooth surface moves straightly toward a corresponding central tooth surface of the inner teeth  12 A of the ratchet  10 , while other teeth enter the inner teeth  12 A with tooth surfaces thereof face corresponding tooth surfaces of the inner teeth  12 A at an oblique angle. 
     However, as described above, since the tooth surfaces of the outer teeth  31  have a shape in which the tooth height gradually decreases from the central tooth surface toward the tooth surfaces on both end sides in the rotation direction, the tooth surfaces of the outer teeth  31  other then the central tooth surface can be brought into a state (meshing state) of entering the tooth surfaces of the inner teeth  12 A without being abutted against the tooth surfaces of the inner teeth  12 A even when the tooth surfaces other than the central tooth surface enter the tooth surfaces of the inner teeth  12 A at an oblique angle. Since a tooth surface shape of the outer teeth  31  is the same as that disclosed in JP-A-2015-29635 and the like, detailed description thereof will be omitted. 
     As shown in  FIG. 9 , the to-be-described rotation cam  40  set at the central portion of the guide  20  is set to face, in the radial direction, inner circumferential regions of the main body surface portions  30 A of the pawls  30 . By such setting, the pawls  30  are provided in a state in which the main body surface portions  30 A face the rotation cam  40  in the radial direction and the offset surface portions  30 B face the rotation cam  40  in the axial direction. 
     As shown in  FIG. 5 , a pressed surface portion  32  is formed on an inner circumferential surface portion of the main body surface portion  30 A of each pawl  30 . The pressed surface portion  32  faces the rotation cam  40  in the radial direction and is pressed outward from an inner side in the radial direction with the rotation of the rotation cam  40 . A pull-in hole  33  is formed to penetrate, in the axial direction, an intermediate portion of the offset surface portion  30 B of each pawl  30 . The pull-in holes  33  are operated such that pull-in pins  42  formed at corresponding positions of the rotation cam  40  are inserted into the pull-in holes  33  and are pulled inward in the radial direction with the rotation of the rotation cam  40 . The abutting protrusion  34  projecting in the same direction as the extruding direction of the offset surface portion  30 B is formed at an intermediate portion of the main body surface portion  30 A of each pawl  30 . 
     As shown in  FIG. 10 , when the rotation cam  40  is rotated in the shown counterclockwise direction by a spring biasing force of the lock spring  50  hooked between the rotation cam  40  and the guide  20 , the pressed surface portions  32  of the pawls  30  are pressed outward from the inside in the radial direction by corresponding pressing portions  44  formed on an outer circumferential surface portion of the rotation cam  40 . Accordingly, the outer teeth  31  of the pawls  30  are pressed against and meshed with the inner teeth  12 A of the ratchet  10 , and the pawls  30  are held in this state (locked state). 
     Accordingly, the pawls  30  are integrally coupled to the ratchet  10  in the rotation direction, and the relative rotation between the ratchet  10  and the guide  20  is locked via the pawls  30 . Specifically, due to the meshing of the pawls  30  in the radial direction, the ratchet  10  and the guide  20  are locked in a state in which rattling in the radial direction is prevented. Preventing the rattling in this way is also generally referred to as “rattling elimination”. 
     As shown in  FIG. 11 , when the rotation cam  40  is rotated in the shown clockwise direction against the spring biasing force of the lock spring  50  due to an operation on the reclining lever  5 , the pull-in holes  33  of the pawls  30  are pulled inward in the radial direction by the corresponding pull-in pins  42  of the rotation cam  40 . Accordingly, the outer teeth  31  of the pawls  30  are released from the meshing state of being meshed with the inner teeth  12 A of the ratchet  10 , and the pawls  30  are held in this state (unlocked state). Accordingly, a rotation locked state between the ratchet  10  and the guide  20  is released. 
     As shown in  FIG. 9 , the abutting protrusion  34  of each pawl  30  is extruded into a half-punched shape to the substantially same position in the axial direction as the offset surface portion  3011  of each pawl  30 , and is set in a state in which an outer circumferential surface portion  34 A of the abutting protrusion  34  faces the inner circumferential surface of the intermediate cylindrical portion  13  of the ratchet  10  in the radial direction. As shown in  FIGS. 10, 17A and 18A , when a rotation position of the ratchet  10  relative to the guide  20  is in the lock region A 1 , even if the pawls  30  are pushed outward in the radial direction by the rotation cam  40 , the abutting protrusion  34  of each pawl  30  is not pressed against the inner circumferential surface of the intermediate cylindrical portion  13  of the ratchet  10 , and thus does not hinder movement of each pawl  30  meshing with the inner teeth  12 A of the ratchet  10 . 
     As shown in  FIGS. 13, 17B and 18B , when the rotation position of the ratchet  10  relative to the guide  20  is shifted to the free region A 2 , the pawls  30  are pressed outward in the radial direction by the rotation cam  40 , and thus the abutting protrusion  34  of each pawl  30  is pressed against the inner circumferential surface of the intermediate cylindrical portion  13  of the ratchet  10 , so as to stop the movement of each pawl  30  meshing with the inner teeth  12 A of the ratchet  10  in the middle. Hereinafter, the above configurations will be described in detail. 
     The abutting protrusions  34  of the pawls  30  are configured to be different in dimension in the radial direction from a central portion (a position at the rotation center C) of the guide  20  to the outer circumferential surface portion  34 A, that is, different in forming positions in the radial direction, between the main pawl P 1  and the other two sub-pawls P 2 . Specifically, the abutting protrusion  34  of the main pawl P 1  is formed at a position at which the abutting protrusion  34  of the main pawl P 1  protrudes outward in the radial direction than the abutting protrusions  34  of the other two sub-pawls P 2 . 
     As shown in  FIGS. 10, 17A, and 18A , when overlapping in the rotation direction with the first region  13 A (lock region A 1 ) of the intermediate cylindrical portion  13  of the ratchet  10 , the abutting protrusion  34  of the main pawl P 1  is not pushed out to a position at which the abutting protrusion  34  rides on the first region  13 A even if being pushed outward in the radial direction by the rotation cam  40 , and thus does not hinder movement of the main pawl P 1  meshing with the inner teeth  12 A of the ratchet  10 . 
     At this tittle, the abutting protrusions  34  of the other two sub-pawls P 2  are also not pushed out to positions at which the abutting protrusions  34  respectively ride on the second region  13 B and the third region  13 C when being pushed outward in the radial direction by the rotation cam  40 , and thus do not hinder movement of the sub-pawls P 2  meshing with the inner teeth  12 A of the ratchet  10 . That is, the two sub-pawls P 2  are formed at positions inward in the radial direction than the abutting protrusion  34  of the main pawl P 1 . Therefore, even when the two sub-pawls P 2  overlap in the rotation direction with the second region  13 B (relief region A 3 ) and the third region  13 C (relief region A 3 ) which protrude inward in the radial direction than the first region  13 A, the two sub-pawls P 2  are not pushed to positions at which the two sub-pawls P 2  respectively ride on the second region  13 B and the third region  13 C when the being pushed outward in the radial direction by the rotation cam  40 . 
     As shown in  FIGS. 13, 17B, and 18B , when overlapping in the rotation direction with the second region  13 B (free region A 2 ) of the intermediate cylindrical portion  13  of the ratchet  10 , the abutting protrusion  34  of the main pawl P 1  rides on the second region  13 B when being pushed outward in the radial direction by the rotation cam  40 , and thus stops movement of the main pawl P 1  meshing with the inner teeth  12 A of the ratchet  10  in the middle. 
     At this time, even when the abutting protrusions  34  of the other two sub-pawls P 2  overlap in the rotation direction with the corresponding third region  13 C (relief region A 3 ) and the first region  13 A (relief region A 3 ), the abutting protrusions  34  of the other two sub-pawls P 2  are not pushed to positions at which the abutting protrusions  34  ride on the third region  13 C (relief region A 3 ) and the first region  13 A (relief region A 3 ) when being pushed outward in the radial direction by the rotation cam  40 , and thus do not stop outward movement of the sub-pawls P 2  in the radial direction. In such a configuration as well, since the movement of the main pawl P 1  is stopped in the middle to stop the rotation of the rotation cam  40  in the middle, the sub-pawls P 2  are not further pushed outward in the radial direction, and thus the sub-pawls P 2  are held together with the main pawl P 1  in the unlocked state in which meshing movement to the inner teeth  12 A of the ratchet  10  is blocked in the middle. 
     As shown in  FIGS. 4, 5, and 19 to 20 , each of the pawls  30  is formed such that the abutting protrusion  34  and the offset surface portion  30 B are extruded from the main body surface portion  30 A into a half-punched shape in the same axial direction. When the offset surface portion  30 B of each pawl  30  is shaped, an accuracy control surface Q that controls accuracy of a shaping surface is not set on the outer circumferential surface portion of the offset surface portion  30 B of each pawl  30 , but on the inner circumferential surface portion (pressed surface portion  32 ) of the main body surface portion  30 A. Accordingly, each pawl  30  has a configuration in which the pressed surface portion  32  is formed with high accuracy. 
     When the abutting protrusion  34  of each pawl  30  is shaped, an accuracy control surface Q that controls accuracy of the shaping surface is set on the outer circumferential surface portion  34 A that faces the outer side in the radial direction. Accordingly, each pawl  30  has a configuration in which the outer circumferential surface portion  34 A is formed with high accuracy. Thus, by shaping each pawl  30  such that the offset surface portion  30 B and the abutting protrusion  34  are extruded into a half-punched shape from the main body surface portion  30 A so as to be arranged and spaced apart from each other in the radial direction, the accuracy control surfaces Q are set on front and back sides as described above and the accuracy of the shaping surfaces can be obtained. 
     The pressed surface portion  32  of each pawl  30  is configured to be pressed from the inner side in the radial direction by the corresponding pressing portion  44  of the rotation cam  40  shown in  FIG. 4 , at regions on both sides in the rotation direction deviated from a formation position of the abutting protrusion  34  of the pawl  30 . Therefore, the pressed surface portion  32  of each pawl  30  is configured such that the accuracy control surfaces Q are set in regions on both sides that do not overlap with the abutting protrusion  34  in the rotation direction, and the accuracy control surfaces Q are not set in a region that overlaps with the abutting protrusion  34  in the rotation direction. According to such a configuration, even when the offset surface portion  30 B and the abutting protrusion  34  of each pawl  30  overlap with each other in the rotation direction, the accuracy control surfaces Q can be appropriately set and each shaping surface can be formed with high accuracy. 
     Rotation Cam  40   
     As shown in  FIG. 5 , the rotation cam  40  is formed by cutting one metal plate-shaped member into a substantially disk shape and extruding the substantially disk-shaped plate member into a half-punched shape in a plate thickness direction (axial direction) at some positions. The rotation cam  40  is set in a state of being accommodated in the cam accommodating groove  24 B formed on the inner surface of the disk main body  21  of the guide  20 . As shown in  FIG. 9 , the rotation cam  40  has a shape in which a plate thickness thereof is substantially equal to that of each pawl  30 . 
     The rotation cam  40  is set to be sandwiched in the axial direction between the inner surface of the disk main body  21  of the guide  20  and the offset surface portions  30 B extruded in a half-punched shape in the axial direction of the pawls  30 . Accordingly, the rotation cam  40  is set in a state of being covered from the outer side in the radial direction by the pressed surface portions  32  that are inner circumferential surface portions of the main body surface portions  30 A of the pawls  30 . 
     As shown in  FIG. 5 , a through hole  41  is formed in a central portion (a position at the rotation center C) of the rotation cam  40 . The operation pin  5 A is inserted into the through hole  41  from an inner side in the axial direction and is coupled with the rotation cam  40  integrally in the rotation direction. The operation pin  5 A is inserted to pass through the through hole  41  of the rotation cam  40  from the inner side to the outer side in the axial direction, and is integrally connected with the reclining lever  5  as shown in  FIG. 1  at a tip end thereof. With the above assembly, the operation pin  5 A integrally rotates the rotation cam  40  along with the operation of pulling up the reclining lever  5 . 
     The operation pin  5 A is integrally coupled to the operation pin  5 A inserted into the seat reclining device  4  on the other side as shown in  FIG. 1  via a connecting rod  5 B. Accordingly, the two operation pins  5 A are rotated at the same time due to the operation of pulling up the reclining lever  5 , and rotation cams  40  of the two seat reclining devices  4  are rotated at the same time. 
     As shown in  FIG. 5 , the rotation cam  40  is formed in a substantially disk shape that is slightly larger than the through hole  21 A formed in the central portion (position at the rotation center C) of the guide  20 . On an outer surface of the rotation cam  40  that faces an inner side of the through hole  21 A of the guide  20 , two hook pins  43  are formed to project in the axial direction. As shown in  FIGS. 2 and 6 , an inner end portion  51  of the lock spring  50  is hooked and fixed to the hook pins  43  in a form of being sandwiched therebetween. As shown in  FIG. 10 , on an inner surface of the rotation cam  40  that faces the offset surface portions  30 B of the pawls  30 , the pull-in pins  42  which are to enter the pull-in holes  33  of the pawls  30  are formed to project in the axial direction. 
     The rotation cam  40  is assembled to the guide  20  in a state of being elastically supported by the guide  20  via the lock spring  50 . Specifically, the assembling is performed in the following procedure. First, the rotation cam  40  is set in the cam accommodating groove  24 B of the guide  20 . Next, the lock spring  50  is set in the through hole  21 A of the guide  20 , the inner end portion  51  of the lock spring  50  is hooked between the hook pins  43  of the rotation cam  40 , and the outer end portion  52  of the lock spring  50  is hooked in the hooking hole  21 Aa extending from the through hole  21 A of the guide  20 . As described above, the rotation cam  40  is assembled to the guide  20  in a state of being elastically supported by the guide  20  via the lock spring  50 . 
     The rotation cam  40  is rotationally biased in the counterclockwise direction as shown in  FIG. 10  with respect to the guide  20  by the spring biasing force of the lock spring  50 ) hooked between the rotation cam  40  and the guide  20 . By the rotation caused by the biasing, the rotation cam  40  constantly presses the pressed surface portions  32  (see  FIG. 9 ) of the pawls  30  from the inner side in the radial direction by the pressing portions  44  projecting from a plurality of locations on the outer circumferential surface portion of the rotation cam  40 , and the pawls  30  are meshed with the inner teeth  12 A of the ratchet  10 . 
     As shown in  FIG. 11 , when the reclining lever  5  in  FIG. 1  is pulled up, the rotation cam  40  is operated to rotate in the shown clockwise direction via the operation pin  5 A. Accordingly, the rotation cam  40  pulls the pawls  30  inward in the radial direction by the pull-in pins  42  inserted into the pull-in holes  33  of the pawls  30 , so as to release the pawls  30  from the meshing state of being meshed with the inner teeth  12 A of the ratchet  10 . Specifically, due to the rotation of the rotation cam  40  in the shown clockwise direction shown, the pull-in pins  42  are pressed against erected inclined surfaces on corresponding inner circumferential edge sides of the pull-in holes  33 , and the pawls  30  are pulled inward in the radial direction. 
     As shown in  FIG. 10 , the rotation cam  40  is configured such that, in the state (locked state) in which the pawls  30  are pushed from the inner side in the radial direction and meshed with the inner teeth  12 A of the ratchet  10 , the inner end portion  51  of the lock spring  50  hooked on the hook pins  43  is disposed in a rotation region between two guide walls M 1  on an upper left side and an upper right side in the figure among the three guide walls  23  formed on the guide  20 . 
     In this state, the rotation cam  40  receives, due to the spring biasing force received from the inner end portion  51  of the lock spring  50 , not only a rotational biasing force in the shown counterclockwise direction relative to the guide  20  but also a biasing force in an eccentric direction to be pushed outward in the radial direction. However, since the three pawls  30  are meshed with the inner teeth  12 A of the ratchet  10 , the rotation cam  40  is supported by the pawls  30  and is held in a centered state at the central portion (the position at the rotation center C) of the guide  20 . 
     As shown in  FIG. 11 , the rotation cam  40  is operated to rotate in the shown clockwise direction shown and the pawls  30  are released from the meshing state of being meshed with the inner teeth  12 A of the ratchet  10 . Thus, the rotation cam  40  is rotated in the shown clockwise direction such that, due to the biasing force in the eccentric direction received from the inner end portion  51  of the lock spring  50 , the rotation cam  40  is pressed against the support surfaces  23 B on inner circumferential side of the two guide walls M 1  as shown in  FIG. 16  while sliding on the support surfaces  23 B of the two guide walls M 1 . At this time, unlike the two guide walls M 1 , the remaining guide wall M 2  (a guide wall M 2  on a lower side in the figure) is not in contact with an outer circumferential surface of the rotation cam  40 , and a slight gap T in the radial direction is generated between the guide wall M 2  and the outer circumferential surface of the rotation cam  40 . 
     With such a configuration, the rotation cam  40  can be appropriately supported by the two guide walls M 1  against which the rotation cam  40  is pressed due to the spring biasing force of the lock spring  50  so as not to move in the axial deviation direction (eccentric direction). The rotation cam  40  can appropriately escape axial deviation (eccentric) movement in a direction in which the remaining guide wall M 2  exists, with the two guide walls M 1  as fulcrums. Therefore, the rotation cam  40  can be smoothly slid and rotated in a release direction without being eccentric. 
     Outer Circumferential Ring  60   
     As shown in  FIGS. 4 and 5 , the outer circumferential ring  60  is formed in a substantially cylindrical shape having a hollow disk plate-shaped base (flange portion  62 ) by punching a thin metal plate member into a ring shape and drawing an outer circumferential edge portion of the punched metal plate to project into a cylindrical shape in the axial direction. Specifically, the outer circumferential ring  60  includes the hollow disk plate-shaped flange portion  62  having a straight surface facing the axial direction, and a coupling portion  61  projecting from an outer circumferential edge portion of the flange portion  62  into a substantially cylindrical shape in the axial direction. 
     Specifically, the outer circumferential edge portion of the outer circumferential ring  60  has a shape of being extruded to project into a stepped cylindrical shape with two stages in the axial direction. Accordingly, a cylindrical part on an outer circumferential side of the stepped cylinder is formed as the substantially cylindrical coupling portion  61 , and a cylindrical part on an inner circumferential side is formed as a stepped portion  63  having a projecting length in the axial direction shorter than that of the coupling portion  61 . 
     The outer circumferential ring  60  is mounted across the outer circumferential portions of the ratchet  10  and the guide  20  as follows, and is assembled in a state of preventing the ratchet  10  and the guide  20  from coming off in the axial direction. First, the three pawls  30 , the rotation cam  40 , and the lock spring  50  are set on the guide  20 . Next, the ratchet  10  is assembled to the guide  20 , and the ratchet  10  and the guide  20  are set inside the cylinder of the outer circumferential ring  60  (inside the coupling portion  61 ). 
     Then, as shown in  FIG. 15 , a projection tip portion (crimped portion  61 A) of the coupling portion  61  is crimped onto an outer surface of the cylindrical portion  22  of the guide  20 . As described above, the coupling portion  61  of the outer circumferential ring  60  is integrally coupled to the cylindrical portion  22  of the guide  20 , and the flange portion  62  is abutted against the ratchet  10  from the outer side in the axial direction, Accordingly, the outer circumferential ring  60  is mounted across the outer circumferential portions of the ratchet  10  and the guide  20 , and is assembled to prevent the ratchet  10  and the guide  20  from coming off in the axial direction. 
     The assembling will be described more specifically, and the outer circumferential ring  60  is set in a state in which the cylindrical portion  22  of the guide  20  is abutted in the axial direction against the stepped portion  63  by sequentially assembling the ratchet  10  and the guide  20  into the cylindrical portion (the coupling portion  61 ). Then, the cylindrical portion  12  of the ratchet  10  is set in a state of being abutted against the flange portion  62  from the inner side in the axial direction. Then, by the above setting, the cylindrical portion  22  of the guide  20  is fitted completely in the axial direction into the cylindrical coupling portion  61  of the outer circumferential ring  60 . 
     After the above setting, the tip portion (crimped portion  61 A) of the coupling portion  61  of the outer circumferential ring  60 , which extends outward in the axial direction from the cylindrical portion  22  of the guide  20  is bent inward in the radial direction and crimped onto the outer surface of the cylindrical portion  22  of the guide  20  such that the cylindrical portion  22  is sandwiched in the axial direction between the crimped portion  61 A and the stepped portion  63 . Accordingly, the outer circumferential ring  60  is integrally coupled to the guide  20 , and the ratchet  10  is abutted against the flange portion  62  from the outer side in the axial direction and thus not comes off in the axial direction. 
     Specifically, the flange portion  62  of the outer circumferential ring  60  is set such that a tip end portion thereof protruding inward in the radial direction is attached to an inclined surface  13 G formed on an outer surface portion of the ratchet  10  in the axial direction at a position at which the intermediate cylindrical portion  13  and the cylindrical portion  12  are continuous. The inclined surface  13 G has a shape facing obliquely outward in the radial direction, Therefore, by attaching the tip end portion of the flange portion  62  of the outer circumferential ring  60  to the inclined surface  13 G, the ratchet  10  is prevented from rattling outward in the axial direction or outward in the radial direction. 
     Here, as shown in  FIGS. 5 and 7 , oblique abutting portions crimped to project inward in the axial direction are firmed on the flange portion  62  of the outer circumferential ring  60  at three positions in the rotation direction. When the oblique abutting portions  62 A are disposed to overlap in the rotation direction with projecting inclined surfaces  13 H that are formed on the inclined surface  13 G of the ratchet  10  at three positions in the rotation direction and that each have a surface oriented outward in the axial direction and outward in the radial direction, each oblique abutting portion  62 A rides on the corresponding projecting inclined surface  13 H. Due to the ride-on, the oblique abutting portions  62 A are held in a state in which the ratchet  10  is more appropriately prevented from rattling outward in the axial direction and outward in the radial direction. 
     Each of the oblique abutting portions  62 A of the flange portion  62  is formed by partially bending the flange portion  62  obliquely inward in the axial direction with a joint with the stepped portion  63  as a base point. According to a shape of a die against which the ratchet  10  is abutted during half-punching, each projecting inclined surface  13 H termed on the inclined surface  13 G of the ratchet  10  is formed to project substantially parallel to the inclined surface  13 G. 
     The projecting inclined surfaces  13 H are arranged at equal intervals on the inclined surface  13 G at three positions in the rotation direction. The projecting inclined surfaces  13 H each have a length in the rotation direction of about 20 degrees. On both side portions of each projecting inclined surface  13 H in the rotation direction, guide inclined surfaces  13 H 1  that are raised to obliquely smooth a step between the projecting inclined surface  13 H and the inclined surface  13 G are formed. The oblique abutting portions  62 A formed on the flange portion  62  of the outer circumferential ring  60  are also arranged at equal intervals on the flange portion  62  at three positions in the rotation direction. The oblique abutting portions  62 A each have a length in the rotation direction of about 20 degrees. 
     The outer circumferential ring  60  is configured such that, when the backrest angle of the seat back  2  is in an angular region (abutting region B 1 ) between a torso angle Pd (about  20  degrees) and the initial lock position Pb in a posture that the seat back  2  stands up straightly as shown in  FIG. 21 , the oblique abutting portions  62 A of the flange portion  62  ride on and are abutted against the corresponding projecting inclined surfaces  13 H formed on the inclined surface  13 G of the ratchet  10  as shown in  FIGS. 22 and 23 . 
     Therefore, the outer circumferential ring  60  is held in a state in which the ratchet  10  is appropriately prevented from rattling in the axial direction and the radial direction by the oblique abutting portions  62 A. At this time, as shown in  FIG. 24 , a general surface of the flange portion  62  of the outer circumferential ring  60  is in a non-abutting state of being separated from a general surface of the inclined surface  13 G of the ratchet  10 . As shown in  FIG. 21 , the abutting region B 1  is set in an angular region of about 40 degrees in which the backrest angle of the seat back  2  is between an angular position at which the seat back  2  is inclined forward by about 10 degrees from the initial lock position Pb (upright position), and an angular position at which the seat back  2  is inclined rearward by about 10 degrees from the torso angle Pd. 
     In the abutting region B 1 , as shown in  FIG. 22 , since an effect of preventing the rattling of the ratchet  10  by the outer peripheral ring  60  is relatively strong, an effect of a sliding friction resistance force associated with the abutment between the ratchet  10  and the outer circumferential ring  60  tends to exert a prevention force on the rotational movement of the ratchet  10  with respect to the guide  20 . However, when the seat back  2  is in the angular region in which the seat back  2  stands up, the biasing force of the return spring  6  (see  FIG. 1 ) that biases the seat back  2  in the forward rotation direction is relatively strong. Therefore, even if an effect of the rattling elimination is strong, the seat back  2  can be smoothly rotationally moved. 
     The outer circumferential ring  60  is configured such that, as shown in  FIG. 25 , when the backrest angle of the seat back  2  is shifted to an angular region deviated rearward from the abutting region B 1  shown in  FIG. 21 , as shown in  FIGS. 26 to 28 , the projecting inclined surfaces  13 H formed on the inclined surface  13 G of the ratchet  10  are deviated in the rotation direction from the corresponding oblique abutting portion  62 A of the flange portion  62 . As a result, the outer circumferential ring  60  is in a non-abutting state (non-abutting region B 2 ) in which the inclined surface  13 G of the ratchet  10  faces each oblique abutting portion  62 A of the flange portion  62  with a slight gap. 
     In the non-abutting state, an effect of preventing rattling of the ratchet  10  by the outer circumferential ring  60  is weak, but the ratchet  10  can be smoothly and rotationally moved with respect to the guide  20  by the effect. Therefore, when the seat back  2  is in the angular region in which the seat back  2  is rearward tilted, although an effect of the biasing forces of the return springs  6  (see  FIG. 1 ) that biases the seat back  2  in the forward rotation direction are relatively weak, the seat back  2  can be smoothly erected forward. 
     The outer circumferential ring  60  is configured such that, as shown in  FIG. 29 , when the backrest angle of the seat back  2  is shifted to an angular region deviated forward from the abutting region B 1  shown in  FIG. 21 , as shown in  FIGS. 30 to 32 , the projecting inclined surfaces  13 H formed on the inclined surface  13 G of the ratchet  10  are deviated in the rotation direction from the corresponding oblique abutting portion  62 A of the flange portion  62 . As a result, the outer circumferential ring  60  is in a non-abutting state (non-abutting region B 2 ) in which the inclined surface  13 G of the ratchet  10  faces each oblique abutting portion  62 A of the flange portion  62  with a slight gap. 
     In the non-abutting state, an effect of preventing rattling of the ratchet  10  by the outer circumferential ring  60  is weak, but the ratchet  10  can be smoothly and rotationally moved with respect to the guide  20  by the effect. Therefore, when the seat back  2  is in the angular region in which the seat back  2  is forward tilted, although a force for erecting the seat back  2  rearward is increased, the seat back  2  can be relatively smoothly erected rearward, 
     Ratting Elimination Structure of Main Pawl P 1   
     The main pawl P 1  has a rattling elimination structure in which, as shown in  FIG. 34 , when the main pawl P 1  is pressed by the rotation cam  40  and meshed with the inner teeth  12 A of the ratchet  10 , the main pawl P 1  is slightly inclined so as to stretch between the guide walls  23  on both sides to eliminate the rattling in the rotation direction. Hereinafter, the rattling elimination structure of the main pawl P 1  will be described in detail. 
     On the main pawl P 1 , a first protrusion  35 A projecting toward a facing guide wall  23  is formed on a side portion of the main body surface portion  30 A on a shown counterclockwise direction side (right side in the figure). A second protrusion  35 B projecting toward a facing guide wall  23  is also formed on a side portion of the main body surface portion  30 A of the main pawl P 1  on a shown clockwise direction side (left side in the figure). 
     The first protrusion  35 A is formed at a position closer to an inner side than a center in the radial direction on the side portion of the main body surface portion  30 A of the main pawl P 1  on the shown counterclockwise direction side. The first protrusion  35 A is formed to project in the shown counterclockwise direction in a projection curved surface shape having a uniform cross section over the entire area of the main pawl P 1  in the plate thickness direction. The second protrusion  35 B is formed at a radially outer end portion position on the side portion of the main body surface portion  30 A of the main pawl P 1  on the shown clockwise direction side. The second protrusion  35 B is formed to project in the shown clockwise direction in a trapezoidal shape having a uniform cross section over the entire area of the main pawl P 1  in the plate thickness direction. 
     As shown in  FIG. 35 , the main pawl P 1  has a configuration in which a gap S in the rotation direction is set between the main pawl P 1  and the guide walls  23  on both sides thereof in order to ensure an inward and outward sliding performance in the radial direction. 
     However, due to the setting of the gap S, when the main pawl P 1  is pushed outward in the radial direction by the rotation cam  40  as described above in  FIG. 10 , rattling in which the main pawl P 1  is inclined in the rotation direction between the guide walls  23  may occur. 
     Specifically, as shower in  FIG. 35 , the main pawl P 1  is configured to be pressed outward from the inner side in the radial direction by the rotation cam  40  at a pressing point R that is eccentric in the shown counterclockwise direction from a central position in the rotation direction. Therefore, the main pawl P 1  is configured to be pushed out to a position at which the main pawl P 1  is meshed with the inner teeth  12 A of the ratchet  10  while being rotated in the shown clockwise direction between both guide walls  23  with the pressing point R as a fulcrum, due to the pressing force. Alternatively, the main pawl P 1  is configured such that, after the central tooth surface is meshed with the inner teeth  12 A of ratchet  10 , the main pawl P 1  may be rotated in the shown clockwise direction with a meshing point K of the central tooth surface that is meshed most deeply with the inner teeth  12 A as a fulcrum. 
     When the rotation of the main pawl P 1  occurs, the main pawl P 1  is inclined so as to stretch between both guide walls  23 , and the main pawl P 1  can be brought to a state in which rattling in the rotation direction is eliminated. However, when the inclination is large, the main pawl P 1  may be moved such that the tooth surface on one end side, centering on the central tooth surface of the outer teeth  31  which is meshed most deeply with the inner teeth  12 A of ratchet  10 , reduces in a meshing depth with the inner teeth  12 A. Therefore, in order to prevent occurrence of such a problem, the main pawl P 1  has a configuration in which, when the main pawl P 1  is inclined between both guide walls  23 , the first protrusion  35 A and the second protrusion  3513  are respectively abutted against the guide walls  23  on both sides, so that the main pawl P 1  is not greatly inclined, and the rattling in the rotation direction can be eliminated. 
     Specifically, as shown in  FIG. 35 , when the main pawl P 1  is pressed outward from the inner side in the radial direction by the rotation cam  40 , the main pawl P 1  is rotated in the shown clockwise direction. However, due to the rotation, the first protrusion  35 A is abutted with the facing guide wall  23 , and thus the rotation of the main pawl P 1  in the same direction is stopped at an early stage. Then, when the main pawl P 1  is meshed with the inner teeth  12 A of the ratchet  10  from that state, a rotational force in the shown clockwise direction around the meshing point K between the central tooth surface of the outer teeth  31  and the inner tooth  12 A is applied to the main pawl P 1  due to a force applied from the pressing point R. 
     As a result, the main pawl P 1  is applied with a pressing force due to the above rotational force on the guide wall  23  on the side with which the first protrusion  35 A is abutted. Then, as a reaction, the main pawl P 1  is applied with a rotational force for pushing the inner teeth  12 A with which the central tooth surface (meshing point K) is abutted back to the shown clockwise direction with the abutting point between the first protrusion  35 A and the guide wall  23  as a fulcrum. Then, as shown in  FIG. 36 , the main pawl P 1  is slightly rotated in the shown clockwise direction with the abutting point between the first protrusion  35 A and the guide wall  23  as a fulcrum and pushes the ratchet  10  in the same direction, and thus the second protrusion  35 B is abutted against the facing guide wall  23 . 
     The rotation of the main pawl P 1  is stopped at an early stage due to the abutment of the second protrusion  35 B with the guide wall  23 . Then, due to the abutment, the main pawl P 1  is meshed with the inner teeth  12 A of the ratchet  10  in a state in which rattling of the main pawl P 1  in the rotation direction between the guide walls  23  is eliminated. 
     As described above, the structure in which the first protrusion  35 A and the second protrusion  35 B of the main pawl P 1  are abutted against the guide walls  23  on both side appropriately prevents the rattling in which the main pawl P 1  is inclined in the rotation direction between the guide walls  23 . As a result, the tooth surfaces on both ends of the outer teeth  31  of the main pawl P 1  can be maintained in a well-balanced meshing state of being meshed with the inner teeth  12 A of the ratchet  10  instead of shallow meshing. 
     Any phenomenon in the abutment of the main pawl P 1  against the guide wall  23  on each side and the meshing of the central tooth surface (meshing point K) of the outer teeth  31  with the inner teeth  12 A of the ratchet  10  may occur first. That is, no matter which phenomenon occurs first, the reaction caused by the phenomenon causes the other of the abutment and meshing. As described above, the main pawl P 1  is meshed with the ratchet  10  in a state in which rattling between the main pawl P 1  and the guide  20  in the rotation direction is eliminated, thus even there is rattling between other sub-pawls P 2  and the guide  20  in the rotation direction as described in  FIG. 10 , the rattling in the rotation direction between the ratchet  10  and the guide  20  can be appropriately reduced. 
     Overview 
     In summary, the seat reclining device  4  according to the present embodiment has the following configuration. In the following description, reference numerals in parentheses correspond to respective configurations shown in the above embodiment. 
     That is, a vehicle seat reclining device ( 4 ) includes: a ratchet ( 10 ) and a guide ( 20 ) assembled in an axial direction to be rotatable relative to each other; a pawl ( 30 ) supported from both sides in a rotation direction by a pair of guide walls ( 23 ) provided on the guide ( 20 ), and configured to be meshed with the ratchet ( 10 ) due to movement in which the pawl ( 30 ) is pressed outward in a radial direction, so as to restrict the relative rotation between the ratchet ( 10 ) and the guide ( 20 ); and a cam ( 40 ) configured to press and move the pawl ( 30 ) outward from an inner side in the radial direction. 
     The pawl ( 30 ) has an eccentric structure in which the pawl ( 30 ) is pressed and inclined to one side in the rotation direction between the pair of guide walls ( 23 ) due to a pressing force received from the cam ( 40 ), and has a first protrusion ( 35 A) that projects from a side surface of the pawl ( 30 ) on the one side in the rotation direction and restricts the inclination of the pawl ( 30 ) by contact with the guide wall ( 23 ) that the first protrusion ( 35 A) faces. 
     According to the above configuration, although a gap (S) in the rotation direction is provided between the pawl ( 30 ) and each guide wall ( 23 ), the inclination of the pawl ( 30 ) in the gap (S) can be restricted by the abutment between the first protrusion ( 35 A) and the guide wall ( 23 ). Therefore, a sliding performance of the pawl ( 30 ) can be ensured and the rattling can be prevented at the same time. 
     The pawl ( 30 ) further has a second protrusion ( 35 B) that projects from a side surface of the pawl ( 30 ) on the other side in the rotation direction and holds, by contact with the guide wall ( 23 ) that the second protrusion ( 35 B) faces, the pawl ( 30 ) in a posture in which the pawl ( 30 ) is in contact with both of the pair of guide walls ( 23 ). According to the above configuration, the pawl ( 30 ) can be abutted against both guide walls ( 23 ) and held in a state in which the gap (S) in the rotation direction is closed, and the rattling of the pawl ( 30 ) can be prevented more appropriately. 
     The second protrusion ( 35 B) is located outward in the radial direction than the first protrusion ( 35 A). 
     According to the above configuration, the second protrusion ( 35 B) can be abutted against the guide wall ( 23 ) at a relatively early stage and restrict inclination of the pawl ( 30 ) when the pawl ( 30 ) is inclined, with an abutting point between the first protrusion ( 35 A) and the guide wall ( 23 ) as a base point, in a direction to close the gap (S) between the guide wall ( 23 ) and the other side surface of the pawl ( 30 ) on an outer circumferential side close to the meshing portion with the ratchet ( 10 ). 
     Further, a plurality of pawls ( 30 ) are provided, and the first protrusion ( 35 A) is firmed only on a specific pawl (P 1 ). According to the above configuration, the rattling of the pawl ( 30 ) can be reasonably prevented. 
     Second Embodiment 
     Subsequently, a configuration of the seat reclining device  4  according to a second embodiment of the present invention will be described with reference to  FIG. 37 . In the present embodiment, the rattling elimination structure of the main pawl P 1  is formed by a first protrusion  35 C and the second protrusion  35 B formed on side portions of the main pawl P 1 . The first protrusion  35 C is formed at a position closer to an outer side than a center in the radial direction on a side portion of the main body surface portion  30 A of the main pawl P 1  on the shown counterclockwise direction side (right side in the figure). The first protrusion  35 C is firmed to project in the shown counterclockwise direction in a projection curved surface shape having a uniform cross section over the entire area of the main pawl P 1  in a plate thickness direction. The second protrusion  35 B is formed at the same position as that shown in the first embodiment. 
     As described above, by forming the first protrusion  35 C at a position closer to the outer circumferential side of the main body surface portion  30 A of the main pawl P 1 , the following effects can be obtained. That is, after the first protrusion  35 C is abutted against the facing guide wall  23 , even if the main pawl P 1  receives a fierce from the ratchet  10  by which the main pawl P 1  is pushed back in the shown counterclockwise direction, due to an action of the pressing force received from the rotation cam  40 , the main pawl P 1  is easily pushed in the shown clockwise direction with an abutting point between the first protrusion  35 C and the guide wall  23  as a fulcrum. 
     Therefore, the first protrusion  35 C and the second protrusion  35 B can be appropriately pressed against the guide walls  23  on both sides. Configurations other than the above are the same as those shown in the first embodiment and are accordingly denoted by the same reference numerals and detailed descriptions thereof are omitted. 
     Third Embodiment 
     Schematic Configuration of Seat Reclining Device  4  (Vehicle Seat Reclining Device) 
     Subsequently, a configuration of the seat reclining device  4  according to a third embodiment of the present invention will be described with reference to  FIG. 38 . In the present embodiment, the rattling elimination structure of the main pawl P 1  is formed by a first protrusion  35 D and a second protrusion  35 E formed on side portions of the main pawl P 1 . The first protrusion  35 D and the second protrusion  35 E each have a shape in which a protrusion slope extends over the entire area from a radially inner edge portion to a radially outer edge portion of the main pawl P 1 . 
     Specifically, a protrusion apex of the first protrusion  35 D is set at a position (the same position as the second embodiment) closer to an outer side than a center in the radial direction on the main body surface portion  30 A of the main pawl P 1 . The first protrusion  35 D is firmed to project uniformly in cross section over the entire area of the main pawl P 1  in a plate thickness direction. The first protrusion  35 D has a shape in which protrusion slopes extend from the protrusion apex respectively to a radially inner edge portion and a radially outer edge portion of a side portion of the main pawl P 1 . 
     Specifically, the first protrusion  35 D is configured such that a slope extending outward in the radial direction from the protrusion apex is formed to extend straight to an outer edge portion of a side region of the main body surface portion  30 A excluding the outer teeth  31 . Further, the first protrusion  35 D is configured such that a slope extending inward in the radial direction from the protrusion apex is formed to extend straight to an inner edge portion of a side region of the offset surface portion  30 A beyond the side region of the main body surface portion  30 A. 
     A protrusion apex of the second protrusion  35 E is set at a position (a position in a vicinity of an outer edge portion) closer to an outer side than a center in the radial direction on the main body surface portion  30 A of the main pawl P 1 . The second protrusion  35 E is firmed to project uniformly in cross section over the entire area of the main pawl P 1  in a plate thickness direction. The second protrusion  35 E has a shape in which protrusion slopes extend from the protrusion apex respectively to a radially inner edge portion and a radially outer edge portion of a side portion of the main pawl P 1 . 
     Specifically, the second protrusion  35 E is configured such that a slope extending outward in the radial direction from the protrusion apex is formed to extend straight to an outer edge portion of a side region of the main body surface portion  30 A excluding the outer teeth  31 . Further, the second protrusion  35 E is configured such that a slope extending inward in the radial direction from the protrusion apex is formed to extend straight to an inner edge portion of a side region of the offset surface portion  30 A beyond the side region of the main body surface portion  30 A. 
     The first protrusion  35 D and the second protrusion  35 E are formed before the offset surface portion  30 B of the main pawl P 1  is extruded into a half-punched shape from the main body surface portion  30 A. By the above machining procedure, the first protrusion  35 D and the second protrusion  35 E have a configuration that enables simpler and more accurate shaping than those formed after the half-punched machining. By setting each of the first protrusion  35 D and the second protrusion  35 E into a shape in which long slopes extend inward and outward in the radial direction, the first protrusion  35 D and the second protrusion  35 E can be formed simply and with high accuracy as compared with those partially formed on the side portions of the main pawl P 1 . 
     Further, the first protrusion  35 B and the second protrusion  35 E are configured to have higher structural strength than those partially formed on the side portions of the main pawl P 1 . The first protrusion  35 D and the second protrusion  35 E each may be formed such that the protrusion slope extends at least over the entire area in the radial direction of the main body surface portion  30 A, and may not extend to the offset surface portion  30 B. Configurations other than the above are the same as those shown in the first embodiment and are accordingly denoted by the same reference numerals and detailed descriptions thereof are omitted, 
     Overview 
     In summary, the seat reclining device  4  according to the present embodiment has the following configuration. In the following description, reference numerals in parentheses correspond to respective configurations shown in the above embodiment. 
     That is, the pawl ( 30 ) has an eccentric structure in which the paw ( 30 ) is pressed and inclined to one side in the rotation direction between the pair of guide walls ( 23 ) due to a pressing force received from the cam ( 40 ), and has a first protrusion ( 35 D) that projects from a side surface of the pawl ( 30 ) on the one side in the rotation direction and restricts the inclination of the pawl ( 30 ) by contact with the guide wall ( 23 ) that the first protrusion ( 35 D) faces. 
     According to the above configuration, although the gap (S) in the rotation direction is provided between the pawl ( 30 ) and each guide wall ( 23 ), the inclination of the pawl ( 30 ) in the gap (S) can be restricted by the contact between the first protrusion ( 35 D) and the guide wall ( 23 ). Therefore, a sliding performance of the pawl ( 30 ) can be ensured and the rattling can be prevented at the same time. 
     The pawl ( 30 ) further has a second protrusion ( 35 E) that projects from a side surface of the pawl ( 30 ) on the other side in the rotation direction and holds, by contact with the guide wall ( 23 ) that the second protrusion ( 35 E) faces, the pawl ( 30 ) in a posture in which the pawl ( 30 ) is in contact with both of the pair of guide walls ( 23 ). According to the above configuration, the pawl ( 30 ) can be abutted against both guide walls ( 23 ) and held in a state in which the gap (S) in the rotation direction is closed, and the rattling of the pawl ( 30 ) can be prevented more appropriately. 
     The second protrusion ( 35 E) is located outward in the radial direction than the first protrusion ( 35 D). According to the above configuration, the second protrusion ( 35 E) can be abutted against the guide wall ( 23 ) at a relatively early stage and restrict inclination of the pawl ( 30 ) when the pawl ( 30 ) is inclined, with an abutting point between the first protrusion ( 35 D) and the guide wall ( 23 ) as a base point, in a direction to close the gap (S) between the guide wall ( 23 ) and the other side surface of the pawl ( 30 ) on an outer circumferential side close to the meshing portion with the ratchet ( 10 ). 
     Further, the pawl ( 30 ) has a main body surface portion ( 30 A) that receives, from the inner side in the radial direction, the pressing force from the cam ( 40 ), and an offset surface portion ( 30 B) that has a shape of being extruded from the main body surface portion ( 30 A) into a half-punched shape in the axial direction and is disposed adjacently with the cam ( 40 ) in the axial direction. The second protrusion ( 35 E) has a shape in which a slope of the second protrusion ( 35 E) extends over at least an entire area of the main body surface portion ( 30 A) on the side surface of the pawl ( 30 ) on the other side in the rotation direction. According to the above configuration, the structural strength of the second protrusion ( 35 E) can be increased as compared with a configuration in which the second protrusion ( 35 E) is partially formed on the other side surface of the pawl ( 30 ) in the rotation direction. Further, the second protrusion ( 35 E) can be simply shaped. 
     Further, a plurality of pawls ( 30 ) are provided, and the first protrusion ( 35 D) is formed only on a specific pawl (P 1 ). According to the above configuration, the rattling of the pawl ( 30 ) can be reasonably prevented. 
     The first protrusion ( 35 D) has a shape in which a protrusion slope extends over at least an entire area of the main body surface portion ( 30 A) on the side surface of the pawl ( 30 ) on the one side in the rotation direction. According to the above configuration, the structural strength of the first protrusion ( 35 D) can be increased as compared with a configuration in which the first protrusion ( 35 D) is partially formed on the one side surface of the pawl ( 30 ) in the rotation direction. Further, the first protrusion ( 35 D) can be simply shaped. 
     Fourth Embodiment 
     Schematic Configuration of Seat Reclining Device  4  (Vehicle Seat Reclining Device) 
     Subsequently, a configuration of the seat reclining device  4  according to a fourth embodiment of the present invention will be described with reference to  FIG. 39 . In the present embodiment, the rattling elimination structure of the main pawl P 1  is formed by a first protrusion  23 C and a second protrusion  23 D formed on regulating surfaces  23 A of each guide wall  23  which supports the main pawl P 1  from both sides in the rotation direction. 
     Specifically, the first protrusion  23 C is formed to project in a mountain shape at a position of the guide wall  23  at which the main pawl P 1  is abutted against the guide wall  23  from a lateral side at a position (a position corresponding to the abutting point of the second embodiment) closer to the outer side than the center in the radial direction on the main body surface portion  30 A when the main pawl P 1  is meshed with the ratchet  10 . The first protrusion  23 C is formed to project in the shown clockwise direction in a projection curved surface shape having a uniform cross section over the entire area of the guide wall  23  in a plate thickness direction. 
     The second protrusion  23 D is formed to project in a mountain shape at a position of the guide wall  23  at which the main pawl P 1  is abutted against the guide wall  23  from a lateral side at a position (a position in the vicinity of the outer edge portion: a position corresponding to the abutting point of the second embodiment) closer to the outer side than the center in the radial direction on the main body surface portion  30 A when the main pawl P 1  is meshed with the ratchet  10 . The second protrusion  23 D is formed to project in the shown counterclockwise direction in a projection curved surface shape having a uniform cross section over the entire area of the guide wall  23  in a plate thickness direction. 
     The first protrusion  23 C and the second protrusion  23 D are disposed to be located inward in the radial direction than the outer teeth  31  of the main pawl PT, even when the main pawl P 1  is released from the meshing with the ratchet  10  and pulled inward as much as possible in the radial direction. Accordingly, the first protrusion  23 C and the second protrusion  23 D are not abutted against the main pawl P 1  in the radial direction when the main pawl P 1  is pushed outward in the radial direction so as to be meshed with the ratchet  10 . Configurations other than the above are the same as those shown in the first embodiment and are accordingly denoted by the same reference numerals and detailed descriptions thereof are omitted. 
     Overview 
     In summary, the seat reclining device  4  according to the present embodiment has the following configuration. In the following description, reference numerals in parentheses correspond to respective configurations shown in the above embodiment. 
     That is, a vehicle seat reclining device ( 4 ) includes an eccentric structure in which the pawl ( 30 ) is pressed and inclined to one side in the rotation direction between the pair of guide walls ( 23 ) due to a pressing force received from the cam ( 40 ), and a first protrusion ( 23 C) that projects from the guide wall ( 23 ) that faces a side surface of the pawl ( 30 ) on the one side in the rotation direction and restricts the inclination of the pawl ( 30 ) by contact with the pawl ( 30 ). 
     According to the above configuration, although the gap (S) in the rotation direction is provided between the pawl ( 30 ) and each guide wall ( 23 ), the inclination of the pawl ( 30 ) in the gap (S) can be restricted by the contact between the first protrusion ( 23 C) and the pawl ( 30 ). Therefore, a sliding performance of the pawl ( 30 ) can be ensured and the rattling can he prevented at the same time. 
     The vehicle seat reclining device ( 4 ) further includes a second protrusion ( 23 D) configured to project from the guide wall ( 23 ) that faces a side surface of the pawl ( 30 ) on the other side in the rotation direction and restrict the inclination of the pawl ( 30 ) by contact with the pawl ( 30 ), so as to hold the pawl ( 30 ) in a posture in which the pawl ( 30 ) is in contact with both of the pair of guide walls ( 23 ). 
     According to the above configuration, the pawl ( 30 ) can be abutted against both guide walls ( 23 ) and held in a state in which the gap (S) in the rotation direction is closed, and the rattling of the pawl ( 30 ) can he prevented more appropriately. 
     Fifth Embodiment 
     Schematic Configuration of Seat Reclining Device  4  (Vehicle Seat Reclining Device) 
     Subsequently, a configuration of the seat reclining device  4  according to a fifth embodiment of the present invention will be described with reference to  FIG. 40 . In the present embodiment, the rattling elimination structure of the main pawl P 1  is formed by a first protrusion  23 E and a second protrusion  23 F formed on regulating surfaces  23 A of each guide wall  23  which supports the main pawl P 1  from both sides in the rotation direction. The first protrusion  23 E and the second protrusion  23 F each have a shape in which a protrusion slope extends over the entire area from a radially inner edge portion to a radially outer edge portion of each regulating surface  23 A. 
     Specifically, the first protrusion  23 E is set at a position at which a protrusion apex thereof is abutted from a lateral side against the main pawl P 1  at a position (the position corresponding to the abutting point of the fourth embodiment) closer to an outer side than a center in the radial direction on the main body surface portion  30 A when the main pawl P 1  is meshed with the ratchet  10 . The first protrusion  23 E is formed to project uniformly in cross section over the entire area of the guide wall  23  in a plate thickness direction. The first protrusion  23 E has a shape in which protrusion slopes extend from the protrusion apex respectively to a radially inner edge portion (round end) and a radially outer edge portion (round end) of the regulating surface  23 A of the guide wall  23 . 
     Specifically, the first protrusion  23 E is configured such that a slope extending outward in the radial direction from the protrusion apex is formed to extend straight to the radially outer edge portion (round end) of the regulating surface  23 A of the guide wall  23 . Further, the first protrusion  23 E is configured such that a slope extending inward in the radial direction from the protrusion apex is formed to extend straight to the radially inner edge portion (round end) of the regulating surface  23 A of the guide wall  23 . 
     Specifically, the second protrusion  23 F is set at a position at which a protrusion apex thereof is abutted from a lateral side against the main pawl P 1  at a position (a position in a vicinity of an outer edge portion: the position corresponding to the abutting point of the fourth embodiment) closer to an outer side than a center in the radial direction on the main body surface portion  30 A when the main pawl P 1  is meshed with the ratchet  10 . The second protrusion  23 F is formed to project uniformly in cross section over the entire area of the guide wall  23  in a plate thickness direction. The second protrusion.  23 F has a shape in which protrusion slopes extend from the protrusion apex respectively to a radially inner edge portion (round end) and a radially outer edge portion (round end) of the regulating surface  23 A of the guide wall  23 . 
     Specifically, the second protrusion  23 F is configured such that a slope extending outward in the radial direction from the protrusion apex is formed to extend straight to the radially outer edge portion (round end) of the regulating surface  23 A of the guide wall  23 . Further, the second protrusion  23 F is configured such that a slope extending inward in the radial direction from the protrusion apex is formed to extend straight to the radially inner edge portion (round end) of the regulating surface  23 A of the guide wall  23 . 
     By setting each of the first protrusion  23 E and the second protrusion  23 F into a shape in which long slopes extend inward and outward in the radial direction, the first protrusion  23 E and the second protrusion  23 F can be formed simply and with high accuracy as compared with those partially formed on the regulating surfaces  23 A of the guide walls  23 . Further, the first protrusion  23 E and the second protrusion  23 F are configured to have higher structural strength than those partially formed on the regulating surfaces  23 A of the guide walls  23 . 
     The first protrusion  23 E and the second protrusion  23 F each have a shape in which the protrusion apex is located inward in the radial direction than the outer teeth  31  of the main pawl P 1 , even when the main pawl P 1  is released from the meshing with the ratchet  10  and pulled inward as much as possible in the radial direction. Accordingly, the first protrusion  23 E and the second protrusion  23 F are configured such that the slopes erected toward the protrusion apex do not hinder outward movement of the main pawl P 1  in the radial direction when the main pawl P 1  is pushed outward in the radial direction so as to be meshed with the ratchet  10 . Configurations other than the above are the same as those shown in the first embodiment and are accordingly denoted by the same reference numerals and detailed descriptions thereof are omitted. 
     Overview 
     In summary, the seat reclining device  4  according to the present embodiment has the following configuration. In the following description, reference numerals in parentheses correspond to respective configurations shown in the above embodiment. 
     That is, a vehicle seat reclining device ( 4 ) includes an eccentric structure in which the pawl ( 30 ) is pressed and inclined to one side in the rotation direction between the pair of guide walls ( 23 ) due to a pressing force received from the cam ( 40 ), and a first protrusion ( 23 E) that projects from the guide wall ( 23 ) that faces a side surface of the pawl ( 30 ) on the one side in the rotation direction and restricts the inclination of the pawl ( 30 ) by contact with the pawl ( 30 ). 
     According to the above configuration, although the gap (S) in the rotation direction is provided between the pawl ( 30 ) and each guide wall ( 23 ), the inclination of the pawl ( 30 ) in the gap (S) can be restricted by the abutment between the first protrusion ( 23 E) and the pawl ( 30 ). Therefore, a sliding performance of the pawl ( 30 ) can be ensured and the rattling can be prevented at the same time. 
     The vehicle seat reclining device ( 4 ) further includes a second protrusion ( 23 F) configured to project from the guide wall ( 23 ) that faces a side surface of the pawl ( 30 ) on the other side in the rotation direction and restrict the inclination of the pawl ( 30 ) by contact with the pawl ( 30 ), so as to hold the pawl ( 30 ) in a posture in which the pawl ( 30 ) is in abutted with both of the pair of guide walls ( 23 ). According to the above configuration, the pawl ( 30 ) can be abutted against both guide walls ( 23 ) and held in a state in which the gap (S) the rotation direction is dosed, and the rattling of the pawl ( 30 ) can be prevented more appropriately. 
     Further, the second protrusion ( 23 F) has a shape in which a slope of the second protrusion ( 23 F) extends over an entire area of a side surface of the guide wall ( 23 ) that faces the pawl ( 30 ). According to the above configuration, the structural strength of the second protrusion ( 23 F) can be increased as compared with a configuration in which the second protrusion ( 23 F) is partially formed on the guide wall ( 23 ). Further, the second protrusion ( 23 F) can be simply shaped. 
     Further, the first protrusion ( 23 E) has a shape in which a slope of the first protrusion ( 23 E) extends over an entire area of a side surface of the guide wall ( 23 ) that faces the pawl ( 30 ). According to the above configuration, the structural strength of the first protrusion ( 23 E) can be increased as compared with a configuration in which the first protrusion ( 23 E) is partially formed on the guide wall ( 23 ). Further, the first protrusion ( 23 E) can be simply shaped. 
     Other Embodiments 
     Although the embodiments of the present invention have been described using five embodiments, the present invention can be implemented in various forms other than the above embodiments. 
     1. The vehicle seat reclining device of the present invention can be applied to a seat other than a right seat of an automobile, and can also be widely applied to a seat provided for a vehicle other than an automobile such as a railway, or various vehicles such as an aircraft and a ship. The vehicle seat reclining device may couple the seat back to the seat cushion in a state in which the backrest angle can be adjusted, and may also couple the seat back to a base, such as a bracket fixed to a vehicle main body, in a state in which the backrest angle can be adjusted. 
     2. The vehicle seat reclining device may be configured such that the ratchet is coupled to a base fixed to a vehicle main body, such as a seat cushion, and the guide is coupled to a seat back. 
     3. Two or four or more pawls for locking the relative rotation between the ratchet and the guide may be provided adjacently in the rotation direction. An arrangement of the pawls in the rotation direction is not limited to an even arrangement, and the pawls may be arranged in a biased manner. 
     4. The cam that presses the pawls outward from the inner side in the radial direction is not limited to a rotation type configuration, and may be a sliding type configuration in which the cam presses the pawls outward from the inner side in the radial direction by sliding in the radial direction, as disclosed in JP-A-2014-217662 or the like. Further, the operation of pulling back the pawls inward in the radial direction may be performed using a member separated from the cam such as a release plate as disclosed in JP-A-2015-227071 or the like. 
     5. The abutting portion of the outer circumferential ring is obliquely abutted against the ratchet, and may also be abutted against the ratchet straightly from an outer side in the axial direction. The outer circumferential ring may be configured such that the coupling portion is coupled to the ratchet and the abutting portion is abutted against the guide from the outer side in the axial direction. Further, the coupling portion of the outer circumferential ring is coupled by crimping to one of the ratchet and the guide, and may also be coupled by welding. The cylindrical portion may be set on the ratchet, rather than the guide, so as to cover the guide in a manner surrounding from the outer circumferential side. 
     6. The eccentric structure of the pawl, that is, an eccentric structure that receives, due to the pressing force received from the cam, a force by which the pawl is pressed and inclined in one direction in the rotation direction between the pair of guide walls is a configuration in which the pawl is pressed outward from the inner side in the radial direction to a position at which the pawl is eccentric in the rotation direction by the cam, and may also be a configuration in which the pawl is pressed obliquely in the rotation direction by the cam. 
     7. It is sufficient for the second protrusion to be located at least outward in the radial direction than the first protrusion, and does not necessarily have to be located at a position of the radially outer end portion of the pawl. A protrusion shape and projection amount of each of the first protrusion and the second protrusion are appropriately determined by an arrangement of these pawls in the radial direction. 
     That is, a projection height required for the first protrusion reduces as the first protrusion approaches a position closer to the inner side in the radial direction of the pawl. Further a projection height required for the second protrusion reduces as the second protrusion approaches a position closer to the outer side in the radial direction of the pawl. Further, the pawl may have a configuration in which the pawl has only the first protrusion and does not have the second protrusion. One of the first protrusion and the second protrusion may be formed on the pawl and the other of the first protrusion and the second protrusion may be formed on the guide. 
     The present application is based on Japanese Patent Application No. 2019-084148, filed on Apr. 25, 2019 and Japanese Patent Application No. 2020-035602, filed on Mar. 3, 2020 the contents of which are incorporated herein by reference. 
     INDUSTRIAL APPLICABILITY 
     According to the vehicle seat reclining device of the present invention, the sliding performance of the pawl can be ensured and the rattling can be prevented at the same time. The present invention having the effect can be used, for example, as a seat reclining device used in a seat of an automobile or the like. 
     REFERENCE SIGNS LIST 
     
         
           1 : seat 
           2 : seat back 
           2 F: side frame 
           2 Fa: fitting hole 
           2 Fb: penetrating hole 
           2 Fc: locking plate 
           3 : seat cushion 
           3 F: reclining plate 
           3 Fa: fitting hole 
           3 Fb: penetrating hole 
           3 Fc: front stopper 
           3 Fd: rear stopper 
           4 : seat reclining device (vehicle seat reclining device) 
           5 : reclining lever 
           5 A: operation pin 
           5 B: connecting rod 
           6 : return spring 
           10 : ratchet 
           11 : disk main body 
           11 A: through hole 
           11 B: expanded surface portion 
           12 : cylindrical portion 
           12 A: inner teeth 
           13 : intermediate cylindrical portion 
           13 A: first region 
           13 B: second region 
           13 C: third region 
           13 D: first projection portion 
           13 E: second projection portion 
           13 E 1 : relief recess portion 
         Y: gap 
           13 G: inclined surface 
           13 H: projecting inclined surface 
           13 H 1 : guide inclined surface 
         A 1 : lock region 
         A 2 : free region 
         A 3 : relief region 
         M: coupling region 
           14 : dowel 
         B 1 : abutting region 
         B 2 : non-abutting region 
           20 : guide 
           21 : disk main body 
           21 A: through hole 
           21 Aa: hooking hole 
           21 B: dowel 
           22 : cylindrical portion 
           23 : guide wall 
           23 A: regulating surface 
           23 B: support surface 
           23 C: first protrusion 
           23 D: second protrusion 
           23 E: first protrusion 
           23 F: second protrusion 
         M 1 : guide wall 
         M 2 : guide wall 
         T: gap 
           24 A: pawl accommodating groove 
           24 B: cam accommodating groove 
           30 : pawl 
           30 A: main body surface portion 
           30 B: offset surface portion 
           31 : outer teeth 
           32 : pressed surface portion 
           33 : pull-in hole 
           34 : abutting protrusion 
           34 A: outer circumferential surface portion 
           35 A: first protrusion 
           35 B: second protrusion 
           35 C: first protrusion 
           35 D: first protrusion 
           35 E: second protrusion 
         P 1 : main pawl (specific pawl) 
         P 2 : sub-pawl 
         Q: accuracy control surface 
           40 : rotation cam (cam) 
           41 : through hole 
           42 : pull-in pin 
           43 : hook pin 
           44 : pressing portion 
           50 : lock spring 
           51 : inner end portion 
           52 : outer end portion 
           60 : outer circumferential ring 
           61 : coupling portion 
           61 A: crimped portion 
           62 : flange portion 
           62 A: oblique abutting portion 
           63 : stepped portion 
         C: rotation center 
         Pa: forward tilt position 
         Pb: initial lock position 
         Pc: rearward tilt position 
         Pd: torso angle 
         K: meshing point 
         R: pressing point 
         S: gap