Patent Publication Number: US-11046214-B2

Title: Vehicle seat reclining device

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle seat reclining device. More specifically, the present invention relates to a vehicle seat reclining device for adjusting a tilt angle of a seat back. 
     BACKGROUND ART 
     As a vehicle seat reclining device of related art, there is known a device including a stepped lock mechanism capable of adjusting a backrest angle of a seat back at a constant pitch angle (Patent Literature 1). The vehicle seat reclining device described above is configured as a joint device that connects the seat back to a seat cushion in a state where the backrest angle can be adjusted. Specifically, the vehicle seat reclining device described above includes a ratchet and a guide which are made of substantially disc-shaped metal members and which are assembled so as to be rotatable relative to each other, and a lock mechanism that locks the relative rotation thereof. 
     The ratchet described above is coupled to a side frame by fitting and welding a plurality of projections (so-called dowels) formed to protrude from an outer side surface portion of the ratchet into fitting holes formed in the side frame of the seat back. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: WO 2016/129423 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In the related art, a part of an outer peripheral edge shape of the outer side surface portion of the ratchet is recessed inward in a radial direction by half blanking for the purpose of forming a shape on an inner side surface portion side. Also, positions where some of the projections (dowels) are formed and a welding space to the side frame are packed inward in the radial direction, which is disadvantageous in terms of strength. One of the objects of the present invention is to expand a coupling region of a ratchet to a seat frame outward in a radial direction in a vehicle seat reclining device. 
     Solution to Problem 
     [1] According to a first aspect of the present invention, a vehicle seat reclining device includes: 
     a disc-shaped ratchet and a disc-shaped guide, the ratchet and the guide being coaxially assembled in a relatively rotatable manner; 
     a lock mechanism provided between the ratchet and the guide, and capable of restricting relative rotation between the ratchet and the guide; and 
     a retaining ring retaining an assembled state of the ratchet and the guide, and 
     the lock mechanism includes: a plurality of poles supported by the guide movably in a radial direction, the plurality of poles meshing with the ratchet when moving outward in the radial direction so as to restrict the relative rotation between the ratchet and the guide; and a cam for moving the plurality of poles outward or inward in the radial direction, 
     the ratchet has: an annular protruding portion where an outer peripheral portion of the ratchet protrudes to one side in an axial direction; and an outer side surface portion configured to face a seat frame on the other side in the axial direction of the ratchet, 
     the protruding portion has: a first region in which a specific pole of the plurality of poles is allowed to move outward in the radial direction and to mesh with the ratchet; a second region in which the specific pole is prevented from moving outward in the radial direction and from meshing with the ratchet; and a third region in which another pole is located when the specific pole is in the second region, the first region, the second region, the third region being arranged in a peripheral direction, 
     the outer side surface portion has a fourth region configured to be in contact and coupled with the seat frame, and 
     the protruding portion has a shape in which the third region extends further outward in the radial direction than the second region, so that the fourth region has a shape in which a portion of the fourth region, which corresponds to the third region is wider outward in the radial direction than a portion of the fourth region, which corresponds to the second region. 
     According to the first aspect, in the fourth region (coupling region described later) coupled with the seat frame of the outer side surface portion of the ratchet, the portion corresponding to the third region (other region described later) of the protruding portion has a shape is wider outward in the radial direction (shape of an expansion surface portion described later) than the portion corresponding to the second region (free region described later). Therefore, a seat reclining device having such a configuration can expand the portion where the ratchet is coupled to the seat frame to the outer side in the radial direction as compared with a seat reclining device in related art. 
     [2] According to a second aspect of the present invention, in the first aspect described above, 
     the outer side surface portion has a projection protruding toward the other side in the axial direction so as to be fitted into the seat frame, the projection being provided on the fourth region, and 
     the projection has a shape in which a length of the projection in the peripheral direction is equal to or less than a length of the third region in the peripheral direction. 
     According to the second aspect, a wide space in which a space around both ends of the projection (dowel) in the peripheral direction and a space on the outer side in the radial direction of the projection (dowel) are continuous can be assigned in the fourth region (coupling region). Therefore, it is possible to assign a wider area where the ratchet is coupled to the seat frame. 
    
    
     
       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 of a main part of  FIG. 1 . 
         FIG. 3  is an exploded perspective view of  FIG. 2  viewed from an opposite side. 
         FIG. 4  is an exploded perspective view of the vehicle seat reclining device. 
         FIG. 5  is an exploded perspective view of  FIG. 4  viewed from an opposite side. 
         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 sectional view taken along a line IX-IX of  FIG. 1 . 
         FIG. 10  is a sectional view taken along a line X-X of  FIG. 8  showing a locked state of the vehicle seat reclining device. 
         FIG. 11  is a sectional view corresponding to  FIG. 10  showing an unlocked state of the vehicle seat reclining device. 
         FIG. 12  is a sectional view showing a state in which a ratchet is turned to a free region from the state shown in  FIG. 11 . 
         FIG. 13  is a sectional view showing a state in which a locking operation of the vehicle seat reclining device from the state shown in  FIG. 12  is blocked. 
         FIG. 14  is a sectional view showing a state in which the ratchet is turned to an end position of the free region from the state shown in  FIG. 12 . 
         FIG. 15  is an enlarged view of an XV part in  FIG. 9 . 
         FIG. 16  is a sectional view showing a state in which a rotating cam is pressed against a guide wall by being biased. 
         FIGS. 17( a ) to 17( d )  are sectional views showing the change of each pole in the locking operation in accordance with the change in a rotation position of the ratchet, divided into four cases. 
         FIGS. 18( a ) to 18( d )  are schematic diagrams showing a positional relationship between riding protrusions of each pole and a protruding portion of the ratchet in  FIGS. 17( a ) to 17( d ) . 
         FIG. 19  is an outer side view of each pole. 
         FIG. 20  is an inner side view of each pole. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment for carrying out the present invention are described with reference to drawings. 
     First Embodiment 
     (Schematic Configuration of Seat Reclining Device  4 ) 
     First, the configuration of a vehicle seat reclining device  4  (hereinafter, simply referred to as “device  4 ”) according to the first embodiment will be described with reference to  FIGS. 1 to 20 . In the following description, directions such as front, rear, upper, lower, left, and right refer to respective directions shown in the drawings. Further, a “seat width direction” refers to a left-right direction of a seat  1 . 
     As shown in  FIG. 1 , the device  4  according to the present embodiment is applied to the seat  1  that constitutes a right side seat of an automobile. The device  4  described above is configured as a seat reclining adjustment mechanism that connects a seat back  2  that serves as a backrest portion of the seat  1  described above to a seat cushion  3  that serves as a seating portion in a state in which an backrest angle can be adjusted. Specifically, the device  4  described above is provided between the seat back  2  and the seat cushion  3  described above such that a pair of left and right devices  4  are provided. The device  4  is configured to fix or release the backrest angle of the seat back  2  by being switched integrally between a locked state and an unlocked state. 
     Specifically, the devices  4  described above are provided between respective lower end portions of side frames  2 F forming left and right side frames of the seat back  2  described above and respective reclining plates  3 F connected to rear end portions of left and right side frames of the seat cushion  3  located on an outer side in the seat width direction, so that the devices  4  can be relatively rotated or stopped relative to each other coaxially (see  FIGS. 2 and 3 ). 
     The devices  4  described above are usually held in a locked state in which the backrest angle of the seat back  2  is fixed. The devices  4  are released from the locked state all at once by an operation of pulling up a reclining lever  5  provided on a right side portion of the seat cushion  3  which is on a vehicle outer side so as to be switched to an unlocked state in which the backrest angle of the seat back  2  can be changed. The devices  4  are returned to the locked state again by being biased after the operation of pulling up the reclining lever  5  described above is returned. 
     Here, return springs  6  that always apply a spring biasing force to the seat back  2  in a direction in which the seat back  2  rotates to tilt forward are hooked between the side frames  2 F on the left and right sides of the seat back  2  and the reclining plates  3 F arranged on the outer side thereof. Due to the rotational biasing force of these return springs  6 , the seat back  2  is lifted up to a position where the seat back  2  comes into contact with the back of a seated occupant by releasing the fixed state of the backrest angle by the device  4  described above, such that the backrest angle can be freely adjusted back and forth in accordance with the movement of tilting back and forth by the back of the seated occupant. According to such a configuration, the seat back  2  is configured such that the backrest angle can be easily adjusted. 
     The seat back  2  can rotate in a seat front-rear direction in a rotation region of about 180 degrees with respect to the seat cushion  3  described above between a forward tilting position where the seat back  2  is folded up to an upper surface of the seat cushion  3  and a backward tilting position where the seat back  2  is tilted substantially straight to the rear side. Among the rotation region described above, a rotation region of about 90 degrees from an upright position where the backrest angle of the seat back  2  is substantially straight to the upper side to the backward tilting position described above is set as a “lock region” in which the backrest angle of the seat back  2  is returned to a fixed state when the operation of pulling up the reclining lever  5  is released. Further, a rotation region for the backrest angle of the seat back  2  from the upright position to the forward tilting position described above is set as a “free region” in which the backrest angle of the seat back  2  is maintained in a released state without being returned to the fixed state even though the operation of pulling up the reclining lever  5  is released. 
     The lock region and the free region described above respectively correspond to a lock region A 1  and a free region A 2  set in the device  4  described later. With the setting of the free region A 2  described above, when the reclining lever  5  is operated while a person is not seated on the seat  1 , once the seat back  2  is tilted to a position that enters the free region A 2  due to the biasing of the return spring  6  described above, the seat back  2  is tilted to a forward leaning position thereafter even if the operate on the reclining lever  5  is not continued. Here, the lock region A 1  corresponds to a “first region” of the present invention, and the free region A 2  corresponds to a “second region” of the present invention. 
     As shown in  FIGS. 2 and 3 , specifically, the device  4  described above includes a ratchet  10  that is integrally coupled to an outer surface of the side frame  2 F on each side of the seat back  2  described above, and a guide  20  that is integrally coupled to an inner surface of the reclining plate  3 F on each side. The device  4  is configured such that the backrest angle of the seat back  2  is fixed or released by locking or unlocking the relative rotation between the ratchet  10  and the guide  20 . Here, the side frame  2 F described above corresponds to a “seat frame” of the present invention. 
     (Specific Configuration of Device  4 ) 
     Hereinafter, a specific configuration of the pair of left and right devices  4  described above will be described in detail. Since the devices  4  have the same configuration and are symmetrical with respect to each other, the configuration of one device arranged on the vehicle outer side (right side) shown in  FIGS. 2 to 3  will be described as a representative in the following description. 
     As shown in  FIGS. 4 and 5 , the device  4  includes the substantially disc-shaped ratchet  10  and guide  20  that are assembled with each other in an axial direction, three poles  30  assembled between the ratchet  10  and guide  20 , a rotating cam  40  configured to move these three poles  30  inward and outward in the radial direction, a lock spring  50  formed of a spiral spring that biases the rotating cam  40  against the guide  20  in a direction of a lock rotation movement, and a substantially cylindrical outer peripheral ring  60  that is mounted across outer peripheral portions of the ratchet  10  and the guide  20  so as to hold the ratchet  10  and the guide  20  in an assembled state in the axial direction. The ratchet  10 , the guide  20 , the three poles  30 , and the rotating cam  40  are configured to be hardened by being subjected to a quenching treatment after the press molding such that a structural strength is enhanced. Here, the rotating cam  40  described above corresponds to a “cam” of the present invention. Hereinafter, a specific configuration of each member constituting the device  4  described above will be sequentially described in detail. 
     (Ratchet  10 ) 
     As shown in  FIG. 4 , the ratchet  10  is formed by one metal plate member being cut into a substantially disc shape and subjected to half blanking in places in a plate thickness direction (the axial direction). 
     Specifically, an outer peripheral edge portion of a disc main body  11  of the ratchet  10  described above is formed with a cylindrical portion  12  that protrudes in a substantially cylindrical shape in the axial direction, which is a direction of attachment to the guide  20 . Specifically, the cylindrical portion  12  described above is formed by half blanking so that the outer peripheral edge portion of the disc main body  11  protrudes in two steps in the axial direction, and is formed in a stepped cylindrical shape having an inner and outer two-step cylindrical shape in which an intermediate cylindrical portion  13  smaller in the axial direction than the cylindrical portion  12  and protruding in a substantially cylindrical shape is formed on an inner peripheral side. Here, the intermediate cylindrical portion  13  described above corresponds to a “protruding portion” of the present invention. 
     An inner peripheral surface of the cylindrical portion  12  described above is formed with inner peripheral teeth  12 A whose tooth surfaces face inward in the radial direction such that the inner peripheral teeth  12 A are continuously arranged over an entire area in a peripheral direction. The inner peripheral teeth  12 A described above are formed in a tooth surface shape with which outer peripheral teeth  31  formed on an outer peripheral surface of each pole  30  described later can be meshed by being pressed from an inner side in the radial direction. Specifically, the inner peripheral teeth  12 A described above are configured such that the tooth surfaces are arranged in the peripheral direction at equal intervals with a pitch of 2 degrees from each other. 
     Further, an inner peripheral surface of the intermediate cylindrical portion  13  is formed with three peripheral directions (region  13 A, region  13 B, and region  13 C) in which an inner diameter from the central portion (central axis C) and a length in the peripheral direction are individually set, a first projection  13 D and a second projection  13 E that protrude inward in the radial direction from a boundary of some of these regions, and an escape recess  13 F that is recessed outward in the radial direction at a boundary position of the region  13 C with the second projection  13 E described above. 
     The region  13 A, the region  13 B, and the region  13 C are each formed in an inner peripheral surface shape that is curved so as to draw an arc of a concentric circle around the central portion (central axis C). Specifically, the regions  13 A and  13 C are formed in an inner peripheral surface shape having a larger inner diameter than the region  13 B, and the regions  13 A and  13 C are formed in an inner peripheral surface shape having the same inner diameter. 
     As shown in  FIGS. 10, 17 ( a ) and  18 ( a ), when a main pole P 1  of the three poles  30  to be described later is arranged to overlap the region  13 A in the peripheral direction by rotation of the ratchet  10 , the region  13 A described above constitutes the lock region A 1  of the main pole P 1  that allows the main pole P 1  to move outward in the radial direction so as to mesh with the inner peripheral teeth  12 A of the ratchet  10  and to be locked. Here, the main pole P 1  described above corresponds to a “specific pole” of the present invention. 
     Further, when the main pole P 1  is arranged to overlap the region  13 A described above in the peripheral direction, the region  13 B and the region  13 C described above function as other regions A 3  arranged to overlap the remaining two sub poles P 2  of the three poles  30  in the peripheral direction, such that the sub poles P 2  are allowed to move so as to mesh with the inner peripheral teeth  12 A of the ratchet  10 . Here, the other regions A 3  correspond to a “third region” of the present invention. 
     However, when the main pole P 1  described above is arranged to overlap the region  13 B in the peripheral direction by rotation of the ratchet  10  as shown in  FIG. 12 , the region  13 B function as the free region A 2  of the main pole P 1 , such that the main pole P 1  is prevented from moving outward in the radial direction to mesh with the inner peripheral teeth  12 A of the ratchet  10  on the way as shown in  FIGS. 13, 17 ( b ), and  18 ( b ). Here, each sub pole P 2  described above corresponds to “another pole” of the present invention. 
     When the main pole P 1  is arranged to overlap the region  13 B described above in the peripheral direction, the region  13 C and the region  13 A described above function as the other regions A 3  arranged to overlap the remaining two sub poles P 2  in the peripheral direction, such that movement of each sub pole P 2  synchronized with the movement of the main pole P 1  described above escapes in these regions. 
     That is, in the intermediate cylindrical portion  13  of the ratchet  10  described above, the region  13 A described above constitutes the lock region A 1  in which the lock operation of the main pole P 1  is allowed (see  FIGS. 10, 17 ( a ) and  18 ( a )), and the region  13 B constitutes the free region A 2  in which the lock operation of the main pole P 1  is blocked by riding and the ratchet  10  can be freely rotated in the peripheral direction while being held in the unlocked state (see  FIGS. 13, 17 ( b ) and  18 ( b )). 
     As shown in  FIGS. 10, 17 ( a ) and  18 ( a ), when the main pole P 1  is arranged to overlap the region  13 A in the peripheral direction as described above, the region  13 B and the region  13 C function as the other regions A 3  separately, so that the remaining two sub poles P 2  are allowed to perform the lock operation in synchronization with the movement of the main pole P 1 . Further, as shown in  FIGS. 13, 17 ( b ) and  18 ( b ), when the main pole P 1  described above is arranged to overlap the region  13 B in the peripheral direction by the rotation of the ratchet  10  described above, the region  13 C and the region  13 A function as the other regions A 3  separately, so that the lock operation of the remaining two sub poles P 2  performed in synchronization with the movement of the main pole P 1  is blocked midway. 
     As described above, the intermediate cylindrical portion  13  of the ratchet  10  controls to allow and block the lock operation of the main pole P 1  by the region  13 A and the region  13 B described above, and is configured such that the movement of the remaining two sub poles P 2  in synchronization with the movement of the main pole P 1  can escape by other regions (other regions A 3 ) where the remaining two sub poles P 2  are located at this time. 
     In a case where the main pole P described above is pushed outward in the radial direction at a halfway point and is accidentally pressed against a step between the region  13 A and the region  13 B in the peripheral direction when being moved from the lock region A 1  (region  13 A) to the free region A 2  (region  13 B) by the rotation of the ratchet  10  (i.e. in a case where the arrangement is shown in  FIGS. 17( b )  and  18  ( b )), the first projection  13 D and the second projection  13 E function to come into contact with these two sub poles P 2  at the same time as shown in  FIGS. 17( c )  and  18  ( c ) so as to distribute a load caused thereby to the other two sub poles P 2  instead of concentrate only on the main pole P 1 . 
     That is, when the main pole P described above is pressed against the step between the region  13 A and the region  13 B in the peripheral direction due to the rotation of the ratchet  10 , the first projection  13 D and the second projection  13 E described above are formed at positions where the first projection  13 D and the second projection  13 E are pressed against the remaining two sub poles P 2  in the peripheral direction. 
     As shown in  FIGS. 14, 17 ( d ), and  18 ( d ), when the main pole P 1  described above moves to an end position in the peripheral direction on the region  13 B which is the free region A 2  due to the rotation of the ratchet  10 , the escape recess  13 F is configured to be disengaged from the riding state so that the main pole P can be meshed with the inner peripheral teeth  12 A of the ratchet  10  at that position. By the escape recess  13 F, the ratchet  10  is tilted down to an end position of the free region A 2 , that is, the forward tilting position where the seat back  2  is folded up on the upper surface of the seat cushion  3  described above with reference to  FIG. 1 , so that the device  4  is locked at that position and the seat back  2  can be switched to a state where the rotation is stopped. As a result, the seat back  2  can be locked in the forward tilting position so as not to loosely move. 
     As shown in  FIGS. 4 and 5 , a through hole  11 A penetrating in around hole shape is formed at a central portion (on the central axis C) of the disc main body  11  of the ratchet  10  described above. An operation pin  5 A, which is inserted and mounted in a central portion (on the central axis C) of the rotating cam  40  described later, is inserted through the through hole  11 A in a rotation-free state from an outer side in the axial direction. Further, as shown in  FIG. 5 , on an outer surface of the disc main body  11  of the ratchet  10  described above, projections (hereinafter, referred to as “dowels  14 ”) that protrude by being pushed out in an arcuate shape in the axial direction are formed at three positions in the peripheral direction, which are positions arranged on the same circumference around the central portion (on the central axis C) of the disc main body  11 . 
     The dowels  14  described above are formed in such a manner that one dowel is housed in each forming region in the peripheral direction in which the region  13 A, the region  13 B, and the region  13 C of the intermediate cylindrical portion  13  described above are formed. As shown in  FIG. 3 , the ratchet  10  having the configuration described above is assembled in such a manner that the outer surface of the disc main body  11  thereof is in surface contact with the outer surface of the side frame  2 F of the seat back  2  described above, and a contact portion therebetween in welded so that the ratchet  10  is integrally coupled to the side frame  2 F of the seat back  2  (welding portion W). 
     Specifically, the ratchet  10  described above is assembled in a state where three dowels  14  formed on the outer surface of the disc main body  11  are respectively fitted in three fitting holes  2 Fa correspondingly formed in the side frame  2 F of the seat back  2  and penetrating in a substantially arc shape, and peripheral regions (coupling regions A 4 ) of these fitted parts are joined and coupled by laser welding in a state of surface contact with the side frame  2 F (welding portion W). 
     More specifically, the outer surface of the disc main body  11  of the ratchet  10  described above is formed with the coupling regions A 4  which are abutted against the side frames  2 F in a surface contact state and laser-welded on the outer side in the radial direction and on both sides in the peripheral direction of the regions where these three dowels  14  are formed. As shown in  FIG. 7 , the coupling regions A 4  described above are configured such that the region  13 A and the region  13 C of the intermediate cylindrical portion  13  which are formed on the outer peripheral edges of respective coupling regions A 4  are located at positions on the outer side in the radial direction than the region  13 B. Therefore, the coupling regions A 4  are configured such that regions in the forming regions in the peripheral direction in which the region  13 A and the region  13 C are formed each have an expansion surface portion  11 B whose area is expanded in the radial direction as compared with a region in the forming region in the peripheral direction in which the region  13 B is formed. Here, the coupling region A 4  corresponds to a “fourth region” of the present invention. 
     According to such a configuration, the outer surface of the disc main body  11  of the ratchet  10  described above is configured such that these two coupling regions A 4  that each have the expansion surface portion  11 B in the respective forming regions in the peripheral direction in which the region  13 A and the region  13 C are formed are firmly welded to the side frames  2 F more widely abutted toward the outer side in the radial direction than the one coupling region A 4  in the forming region in the peripheral direction in which the region  13 B is formed. 
     More specifically, the welding of the outer surface of the disc main body  11  of the ratchet  10  described above to the side frames  2 F is performed in such a manner that each dowel  14  is surrounded from an outer region in the radial direction across both side regions in the peripheral direction in a C-shape so that welding beads are inserted (welding portion W). The side frame  2 F described above is formed with a passage hole  2 Fb that allows the operation pin  5 A, which is passed through the through hole  11 A formed at the central portion (on the central axis C) of the ratchet  10  described above, to pass through toward the outer side in the axial direction. 
     (Guide  20 ) 
     As shown in  FIG. 5 , the guide  20  is formed by one metal plate member being cut into a substantially disc shape with an outer diameter slightly larger than that of the ratchet  10  and subjected to the half blanking in places in the plate thickness direction (the axial direction). 
     Specifically, on an outer peripheral edge portion of a disc main body  21  of the guide  20  described above, a cylindrical portion  22  is formed to protrude in a substantially cylindrical shape in the axial direction, which is a direction of attachment to the ratchet  10 . The cylindrical portion  22  is formed such that an inner diameter thereof is slightly larger than the outer diameter of the cylindrical portion  12  of the ratchet  10  described above. As shown in  FIG. 9 , the guide  20  described above is set such that the cylindrical portion  12  of the ratchet  10  described above is inserted into the cylindrical portion  22  of the guide  20  in the axial direction. 
     Accordingly, the guide  20  and the ratchet  10  are assembled in a state where the respective cylindrical portions  22 ,  12  thereof are loosely fitted with each other inward and outward in the radial direction, such that relative rotation therebetween is enabled in a state of being supported inward and outward. Then, the guide  20  described above is mounted in a state where the outer peripheral ring  60  to be described later crosses from an outer peripheral side between the cylindrical portion  22  and the cylindrical portion  12  of the ratchet  10  described above, so that the guide  20  is assembled while being prevented from coming off the ratchet  10  in the axial direction via the outer peripheral ring  60  (see  FIGS. 2 and 3 , and  FIGS. 6 to 9 ). 
     As shown in  FIG. 5 , guide walls  23  which are formed by being pushed out in a half-blanking shape so as to protrude in a substantially fan shape in the axial direction, which is a direction of assembling to the ratchet  10 , are formed at three positions in the peripheral direction on an inner surface of the disc main body  21  of the guide  20  described above. These guide walls  23  are formed such that respective outer peripheral surfaces thereof in the radial direction are curved so as to draw arcs of a concentric circular drawn around a central portion (central axis C) thereof. Each of the guide walls  23  described above is set so as to be loosely fitted into the cylindrical portion  12  of the ratchet  10  which is assembled in the cylindrical portion  22  of the guide  20  described above. 
     By forming the guide walls  23  described above, pole accommodating grooves  24 A are formed in regions among arrangement of the guide walls  23  in the peripheral direction on the inner surface of the disc main body  21  described above, so that each of the three poles  30  described later can be set to be slidable inward and outward in the radial direction. Further, a cam accommodating groove  24 B is formed in a center region on the inner surface of the disc main body  21  surrounded by the guide walls  23  described above, so that the rotating cam  40  described later can be set to be rotated axially. 
     As shown in  FIGS. 10 and 11 , the guide walls  23  described above are applied to the respective poles  30  set correspondingly in the pole accommodating grooves  24 A described above so as to face each other from both sides in the peripheral direction by restriction surfaces  23 A, which are both side surfaces in the peripheral direction facing each pole accommodating groove  24 A, and are configured to support each pole  30  from both sides in the peripheral direction so as to guide each pole  30  to be slidable only inward and outward in the radial direction. 
     Further, the guide walls  23  described above are applied to the rotating cam  40  set in the cam accommodating groove  24 B described above so as to face each other from the outer side in the radial direction by a support surface  23 B, which is an inner peripheral surface in the radial direction facing the cam accommodating groove  24 B, and are configured to support the rotating cam  40  from the outer side in the radial direction so as to guide the rotating cam  40  at the central portion (on the central axis C) on the disc main body  21  of the guide  20  to be rotatable only in the peripheral direction. 
     As described in  FIG. 5 , a play filling pin  21 C that is inserted into a wedge-shaped play filling hole  35  formed in the main pole P 1  so as to protrude in a columnar shape in the axial direction is formed on a forming region of the pole accommodating groove  24 A in which the main pole P 1  is set on the inner surface of the disc main body  21  of the guide  20  described above. As shown in  FIG. 11 , when the main pole P 1  described above is pulled inward in the radial direction and is not meshed with the inner peripheral teeth  12 A of the ratchet  10 , the play filling pin  21 C described above is located in an outer region of the wedge-shaped play filling hole  35  in the radial direction where a hole width is wide and does not block the movement of the main pole P 1 . 
     However, as shown in  FIG. 10 , as the main pole P 1  is pushed outward in the radial direction and meshed with the inner peripheral teeth  12 A of the ratchet  10 , the play filling pin  21 C described above is pressed into an inner region in the radial direction where the hole width is narrow in the wedge-shaped play filling hole  35  of the main pole P 1 , so that the play filling pin  21 C can be switched to a state in which the play of the main pole P 1  in the peripheral direction is prevented. According to such a configuration, the main pole P 1  is meshed with the inner peripheral teeth  12 A of the ratchet  10  in a state where the play in the peripheral direction is prevented, and the ratchet  10  and the guide  20  are locked via the main pole P 1  in a state where the play in the peripheral direction therebetween is prevented. 
     As shown in  FIGS. 4 and 5 , each of the guide walls  23  described above is formed with a floating island-shaped bead portion  23 C that is pushed out in a half-blanking shape toward a side opposite to the axial direction which is the direction of assembling to the ratchet  10  at an intermediate portion where a peripheral edge of a protruding region whose shape is expanded in the peripheral direction and the radial direction is left. Each bead portion  23 C is formed as described above, so that each guide wall  23  is configured to have high structural strength capable of firmly supporting each pole  30  from both sides in the peripheral direction without reducing a contact area with each pole  30  for supporting each pole  30  from both sides in the peripheral direction by the restriction surfaces  23 A. 
     Further, at the central portion (on the central axis C) of the disc main body  21  of the guide  20  described above, a through hole  21 A penetrating in a substantially round hole shape is formed in which the lock spring  50  to be described later is accommodated. The through hole  21 A described above is formed with a hanging hole  21 Aa which extends a slender hole shape from a part of a hole shape of the through hole  21 A toward the outer side in the radial direction. An outer end portion  52  of the lock spring  50  set in the through hole  21 A described above is fitted into the hanging hole  21 Aa in the axial direction so as to be integrally fixed in the peripheral direction. 
     As shown in  FIG. 4 , dowels  21 B protruding in a substantially cylindrical shape in the axial direction are formed on an outer surface of the disc main body  21  of the guide  20  described above at three positions in the peripheral direction. Each of these dowels  21 B is formed in such a manner that it is pushed out in the axial direction one by one in regions corresponding to back sides of respective pole accommodating grooves  24 A described above on the outer surface of the disc main body  21  described above. 
     As shown in  FIG. 2 , the guide  20  having the configuration described above is in a state of being firmly and integrally coupled to the reclining plate  3 F by the dowels  21 B protruding from the outer surface of the disc main body  21  described above being fitted into and welded with the corresponding fitting holes  3 Fa formed in the reclining plate  3 F. The reclining plate  3 F described above is formed with a passage hole  3 Fb that allows the operation pin  5 A, which is passed through the through hole  21 A formed at the central portion (on the central axis C) of the guide  20  described above, to pass through toward the outer side in the axial direction. 
     (Pole  30 ) 
     As shown in  FIGS. 4 and 5 , these three poles  30  are separately formed by one metal plate member being cut into a substantially rectangular shape and subjected to the half blanking in places in the plate thickness direction (the axial direction). Specifically, each pole  30  described above has a shape in which an offset surface portion  30 B forming a region on an inner peripheral side in the radial direction of the poles is pushed out in a half-blanking shape by an amount corresponding to a substantially plate thickness in the axial direction, which is the direction of assembling to the ratchet  10 , with respect to a main body surface portion  30 A forming a region on an outer peripheral side. 
     Further, a specific one pole of the three poles  30  described above is configured as the main pole P 1  that has a partly different shape from the other two sub poles P 2  so as to be functionally distinguished. The specific difference will be described later. 
     As shown in  FIGS. 10 and 11 , each pole  30  described above is set so as to be accommodated one by one in respective pole accommodating grooves  24 A formed on the inner surface of the disc main body  21  of the guide  20  described above. With such a setting, each pole  30  is provided in a state of being supported in a planar shape from both sides in the peripheral direction by the restriction surfaces  23 A of the guide walls  23  facing the respective pole accommodating grooves  24 A from both sides in the peripheral direction, and is supported so as to be movable only inward and outward in the radial direction along the restriction surfaces  23 A. 
     Specifically, as shown in  FIG. 9 , when each pole  30  described above is set in the respective pole accommodating grooves  24 A described above, the main body surface portions  30 A of the poles  30  are set so as to be abutted against the inner surface of the disc main body  21  of the guide  20 . Therefore, each of the poles  30  is set such that the inner peripheral teeth  12 A of the cylindrical portion  12  of the ratchet  10  assembled in the cylindrical portion  22  of the guide  20  described above face each other in the radial direction at a position on the outer side in the radial direction of the main body surface portion  30 A. 
     Further, the offset surface portion  30 B of each pole  30  described above is set so as to be spaced from the inner surface of the disc main body  21  of the guide  20  described above in the axial direction, and to overlap the intermediate cylindrical portion  13  of the ratchet  10  described above in the axial direction. 
     As shown in  FIG. 4 , on an outer peripheral surface in the radial direction of the main body surface portions  30 A of each pole  30  described above, the outer peripheral teeth  31  whose tooth surfaces face outward in the radial direction are formed in a shape that is continuously arranged over an entire area in the peripheral direction. The outer peripheral surface in the radial direction on which the outer peripheral teeth  31  of each pole  30  described above are formed is formed into a curved surface shape along the inner peripheral surface of the cylindrical portion  12  on which the inner peripheral teeth  12 A of the ratchet  10  described above are formed. 
     According to such a configuration, the outer peripheral teeth  31  of each pole  30  are pressed against the inner peripheral teeth  12 A of the ratchet  10  from the inner side in the radial direction, so that the entire teeth are meshed with the inner peripheral teeth  12 A of the ratchet  10 . Specifically, the outer peripheral teeth  31  of each pole  30  are configured such that the tooth surfaces are arranged in the peripheral direction at equal intervals with a pitch of 2 degrees from each other, as the inner peripheral teeth  12 A. 
     However, more strictly, with reference to  FIG. 10 , the outer peripheral teeth  31  of each pole  30  described above are formed in such manner that tooth surfaces at the center in the peripheral direction enter and mesh deepest with the inner peripheral teeth  12 A of the ratchet  10 , and a tooth height becomes smaller as the entering depth with respect to the inner peripheral teeth  12 A of the ratchet  10  gradually decreases toward both end sides in the peripheral direction. 
     According to such a configuration, in each pole  30 , in addition to the tooth surfaces at the center position where the tooth surfaces are oriented straight in an entering direction thereof, other tooth surfaces where direction of the tooth surfaces is tilted in a direction different from the entering direction from the same center position toward both end sides in the peripheral direction can also be appropriately meshed with the tooth surfaces of the corresponding inner peripheral teeth  12 A of the ratchet  10  by the movement of each pole  30  toward the outer side in the radial direction without being replaced. The specific tooth surface shape of the outer peripheral teeth  31  is the same as that disclosed in the literature such as JP-A-2015-29635, and therefore a detailed description thereof will be omitted. 
     According to such a configuration, when the outer peripheral teeth  31  are meshed with the inner peripheral teeth  12 A of the ratchet  10 , each pole  30  may receive an action of a biased force such that the entire body is pushed and tilted in either one of the peripheral directions by an action of a pressing force from the inner side in the radial direction, with the deepest meshed center position in the peripheral direction as a fulcrum. However, the above action is appropriately suppressed by the action of the play filling pin  21 C provided on the guide  20  being pressed into the wedge-shaped play filling hole  35  with the play being filled in the peripheral direction when the main pole P 1  is to be meshed with the ratchet  10 . 
     As shown in  FIG. 9 , each pole  30  described above is set in such a manner that the rotating cam  40  which is described later and set at the central portion (on the central axis C) of the guide  20  faces the radial direction in a region at the inner side of the radial direction surrounded by the main body surface portions  30 A. With such a setting, each pole  30  is configured such that the main body surface portions  30 A are provided side by side at positions on the outer side in the radial direction of the rotating cam  40 , and the offset surface portions  30 B are provided so as to overlap the rotating cam  40  in the axial direction. 
     Here, as shown in  FIG. 5 , the inner peripheral surface of the main body surface portion  30 A of each pole  30  described above is formed with pressed surface portions  32  which face the rotating cam  40  described above in the radial direction and which receive an acting force pressed from the inner side to the outer side in the radial direction as the rotating cam  40  rotates. Further, a pull-in hole  33  is formed at an intermediate portion of the offset surface portion  30 B of each pole  30  described above and penetrates in the axial direction so as to be operated such that a corresponding pull-in pin  42  formed on the rotating cam  40  described above is inserted therein and pulled inward in the radial direction as the rotating cam  40  rotates. Further, at an intermediate portion of the main body surface portion  30 A of each pole  30  described above, a riding protrusion  34  that is pushed out in a half-blanking shape in the same axial direction as the offset surface portion  30 B is formed. 
     As shown in  FIG. 10 , the rotating cam  40  described above is rotated in a counterclockwise direction in the figure by a spring biasing force of the lock spring  50  described later which is hooked between the rotating cam  40  and the guide  20 , so that the pressed surface portions  32  of each pole  30  described above is pressed from the inner side to the outer side in the radial direction by a corresponding pressing portion  44  formed on an outer peripheral surface portion of the rotating cam  40 . By the above pressing, the outer peripheral teeth  31  of each pole  30  are pressed against the inner peripheral teeth  12 A of the ratchet  10  described above to be meshed with each other, and are held in such a meshed state. As a result, the poles  30  are integrally coupled to the ratchet  10  in the peripheral direction, and the relative rotation between the ratchet  10  and the guide  20  is locked via each pole  30 . 
     Further, as shown in  FIG. 11 , the rotating cam  40  described above is rotated in a clockwise direction shown in the figure against the spring biasing force of the lock spring  50  by the operation of the reclining lever  5  described above, so that the pull-in hole  33  of each pole  30  described above is pulled inward in the radial direction by the corresponding pull-in pin  42  of the rotating cam  40  inserted therein. By the above pulling, the outer peripheral teeth  31  of each pole  30  do not mesh with the inner peripheral teeth  12 A of the ratchet  10  described above, and are held in such a state (unlocked state). As a result, the rotation locked state between the ratchet  10  and the guide  20  described above is released. 
     As shown in  FIG. 9 , the riding protrusion  34  of each pole  30  described above is pushed out in a half-blanking shape in the same axial direction as the offset surface portion  30 B of each pole  30  described above to the same position, and an outer peripheral surface portion  34 A thereof is provided so as to face the inner peripheral surface of the intermediate cylindrical portion  13  of the ratchet  10  described above in the radial direction. As shown in  FIGS. 10, 17 ( a ), and  18 ( a ), when a rotation position of the ratchet  10  described above with respect to the guide  20  is in the state of the lock region A 1  described above, even if each pole  30  described above is pushed outward in the radial direction by the rotating cam  40 , the riding protrusion  34  of each pole  30  described above is not pressed against the inner peripheral surface of the intermediate cylindrical portion  13  of the ratchet  10  so that the movement of each pole  30  meshing with the inner peripheral teeth  12 A of the ratchet  10  is not blocked. 
     However, as shown in  FIGS. 13, 17 ( b ), and  18 ( b ), by changing the rotation position of the ratchet  10  described above with respect to the guide  20  to the state of the free region A 2  described above, when each pole  30  described above is pushed outward in the radial direction by the rotating cam  40 , the riding protrusion  34  of each pole  30  described above is pressed against the inner peripheral surface of the intermediate cylindrical portion  13  of the ratchet  10  to ride up, so that the movement of each pole  30  meshing with the inner peripheral teeth  12 A of the ratchet  10  is stopped at an intermediate position. 
     Specifically, the riding protrusions  34  of each pole  30  described above are configured such that diameter dimensions from the central portion (on the central axis C) of the guide  20  to the outer peripheral surface portion  34 A of the main pole P 1  and the other two sub poles P 2  are different from each other, that is, forming positions in the radial direction are different from each other. Specifically, the riding protrusion  34  of the main pole P 1  is formed at a position which is projected more outward in the radial direction than the riding protrusions  34  of the other two sub poles P 2 . 
     As shown in  FIGS. 10, 17 ( a ) and  18 ( a ), when the riding protrusion  34  of the main pole P 1  described above is arranged to overlap the region  13 A (lock region A 1 ) of the intermediate cylindrical portion  13  of the ratchet  10  in the peripheral direction, even if the riding protrusion  34  is pushed outward in the radial direction by the rotating cam  40 , the riding protrusion  34  is not pushed out to a position riding on the region  13 A, so that the movement of the main pole P 1  meshing with the inner peripheral teeth  12 A of the ratchet  10  is not blocked. 
     At this time, the riding protrusions  34  of the other two sub poles P 2  are formed at positions on the inner side of the radial direction than the riding protrusion  34  of the main pole P 1  described above, so that even if the riding protrusions  34  are arranged to respectively overlap, in the peripheral direction, the region  13 B and the region  13 C (other regions A 3 ) that protrude inward in the radial direction than the region  13 A described above, the riding protrusions  34  are also not pushed out to positions riding on the region  13 B and region  13 C at the time of being pushed outward in the radial direction by the rotating cam  40 , and therefore, the movement of each sub pole P 2  meshing with the inner peripheral teeth  12 A of the ratchet  10  is not blocked. 
     Further, as shown in  FIGS. 13, 17 ( b ), and  18 ( b ), when the riding protrusion  34  of the main pole P 1  described above is arranged to overlap the region  13 B (free region A 2 ) of the intermediate cylindrical portion  13  of the ratchet  10  in the peripheral direction, the riding protrusion  34  is pushed outward in the radial direction by the rotating cam  40  to ride on the region  13 B, so that the movement of the main pole P 1  meshing with the inner peripheral teeth  12 A of the ratchet  10  is stopped at the intermediate position. 
     However, at this time, even if the riding protrusions  34  of the other two sub poles P 2  are arranged to overlap the corresponding region  13 C and region  13 A (other regions A 3 ) respectively in the peripheral direction, the riding protrusions  34  are also not pushed out to the positions riding on the region  13 C and region  13 A at the time of being pushed outward in the radial direction by the rotating cam  40 , so that the movement of each sub pole P 2  toward the outer side of the radial direction is not stopped at an intermediate position. 
     Even with such a configuration, the movement of the sub poles P 2  toward the outer side of the radial direction of the main pole P 1  is stopped at the intermediate position so that the rotation of the rotating cam  40  is accordingly stopped, and the sub poles P 2  are not pushed outward further in the radial direction, so as to hold together with the main pole P 1  in the unlocked state in which they are prevented from being pressed against the inner peripheral teeth  12 A of the ratchet  10 . Each riding protrusion  34  formed on these two sub poles P 2  described above has a chamfered inclined surface  34 B at a corner on one end side in the peripheral direction on the outer peripheral surface portion  34 A thereof. 
     Each of the inclined surfaces  34 B described above functions as an escape portion that allows the riding protrusions  34  of the sub poles P 2  to pass over in the peripheral direction while escaping to the outer side in the radial direction by an inclined guide so as not to abut against the first projection  13 D and the second projection  13 E in the peripheral direction, when the ratchet  10  is rotated in a direction in which the ratchet  10  is returned from the free region A 2  to the lock region A 1  without operating the reclining lever  5  (when the seat back  2  is lifted up to the rear side), from a state where the riding protrusion  34  of the main pole P 1  described above rides on the free region A 2  (region  13 B) of the ratchet  10 , and the riding protrusions  34  of the sub poles P 2  are located on the region  13 C and the region  13 A respectively as shown in  FIGS. 13, 17 ( b ), and  18 ( b ). 
     Further, as shown in  FIGS. 4 and 5 , in the main body surface portion  30 A of the main pole P 1  described above, the play filling hole  35  that penetrates in a shape in which a hole shape is tapered from the outer side to the inner side in the radial direction is formed in an intermediate portion that is separated from the forming region of the riding protrusion  34  in the peripheral direction. As shown in  FIG. 11 , the play filling hole  35  described above is set such that the play filling pin  21 C protruding from the inner surface of the disc main body  21  of the guide  20  is inserted into the play filling hole  35  when the main pole P described above is set on the guide  20 . With such a setting, the play filling hole  35  does not block the movement of the main pole P 1  with the play filling pin  21 C being positioned in a region where a hole width on the outer side in the radial direction is wide when the main pole P 1  described above is in the unlocked state before meshing with the inner peripheral teeth  12 A of the ratchet  10 . 
     However, as shown in  FIG. 10 , as the main pole P 1  described above is pushed outward in the radial direction and meshed with the inner peripheral teeth  12 A of the ratchet  10 , the play filling hole  35  described above is configured such that the play filling pin  21 C is pressed into a region having a narrow inner hole width in the radial direction and can be switched to a state in which the play of the main pole P 1  in the peripheral direction is prevented. According to such a configuration, the main pole P 1  is meshed with the inner peripheral teeth  12 A of the ratchet  10  in a state where the play in the peripheral direction is prevented, and the ratchet  10  and the guide  20  are locked via the main pole P 1  in a state where the play in the peripheral direction therebetween is prevented. 
     As shown in  FIGS. 4 and 5  and  FIGS. 19 and 20 , each pole  30  described above is formed such that the offset surface portion  30 B and the riding protrusion  34  are pushed out separately in the same axial direction in a half-blanking shape with respect to the main body surface portion  30 A so as to be spaced from each other in the radial direction. At this time, the offset surface portion  30 B of each pole  30  is formed such that a quality control surface Q for imparting accuracy to a molding surface obtained by the half blanking is set, not on an outer peripheral surface portion side which is pushed out in a half-blanking shape and which faces the outer side in the radial direction, but on an inner peripheral surface portion (pressed surface portion  32 ) side of the main body surface portion  30 A that is formed by the half blanking in a manner of facing the inner side in the radial direction. According to such a configuration, each pole  30  is configured such that the pressed surface portion  32  is accurately formed. 
     Further, the riding protrusion  34  of each pole  30  is formed such that the quality control surface Q for imparting accuracy to the molding surface obtained by the half blanking is set on the outer peripheral surface portion  34 A side that is pushed out in a half-blanking shape and that faces the outer side in the radial direction. According to such a configuration, each pole  30  is configured such that the outer peripheral surface portion  34 A and the inclined surface  34 B are accurately formed. As described above, each pole  30  is formed such that the offset surface portion  30 B and the riding protrusion  34  are pushed out separately in the half-blanking shape with respect to the main body surface portion  30 A so as to be spaced from each other in the radial direction, so that the quality control surfaces Q can be set on the front side and the back side to improve the accuracy of the molding surfaces. 
     Specifically, the pressed surface portion  32  of each pole  30  described above is configured such that each region separated from the forming positions of the riding protrusions  34  on both sides in the peripheral direction are pressed by corresponding pressing portions  44  of the rotating cam  40  described with reference to  FIG. 4  from the inner side in the radial direction. Therefore, in reality, the pressed surface portion  32  of each pole  30  is configured such that the quality control surface Q is set in regions on both sides where the arrangement in the peripheral direction does not overlap with the riding protrusions  34 , and the quality control surface Q is not set in a region where the arrangement in the peripheral direction overlaps with the riding protrusion  34 . According to such a configuration, even if the offset surface portion  30 B of each pole  30  and the riding protrusion  34  are arranged to overlap each other in the peripheral direction, the quality control surface Q can be appropriately set for each and molding can be performed well. 
     (Rotating Cam  40 ) 
     As shown in  FIG. 5 , the rotating cam  40  is formed by one metal plate member being cut into a substantially disc shape and subjected to half blanking in places in a plate thickness direction (the axial direction). The rotating cam  40  described above is set in a state of being accommodated in the cam accommodating groove  24 B formed on the inner surface of the disc main body  21  of the guide  20  described above. 
     As shown in  FIG. 9 , the rotating cam  40  described above has a shape having substantially the same plate thickness as each pole  30  described above, and is arranged to be surrounded by the main body surface portion  30 A of each pole  30  from the outer peripheral side in a manner of being sandwiched between the inner surface of the disc main body  21  of the guide  20  described above and the offset surface portion  30 B of each pole  30  pushed out in a half-blanking shape in the axial direction. 
     As shown in  FIG. 5 , at the central portion (on the central axis C) of the rotating cam  40  described above, a through hole  41  is formed in which the operation pin  5 A integrally connected to the reclining lever  5  described above with reference to  FIG. 1  is inserted from the inner side in the axial direction and is integrally mounted in a rotational direction. The operation pin  5 A described above is inserted through the through hole  41  of the rotating cam  40  described above from the inner side to the outer side in the axial direction, and is connected integrally with the reclining lever  5  described above with reference to  FIG. 1  at that point. According to such a configuration, the operation pin  5 A is operated to integrally rotate with the rotating cam  40  in accordance with the operation of pulling up the reclining lever  5  described above. 
     The operation pin  5 A described above is integrally connected to the operation pin  5 A inserted into the device  4  on the other side described above with reference to  FIG. 1  via a connecting rod  5 B. According to such a configuration, the operation pin  5 A on the other side is also integrally rotated, and the rotating cam  40  of the device  4  on the same side is also integrally rotated by the operation of pulling up the reclining lever  5  described above. 
     As shown in  FIG. 5 , the rotating cam  40  described above is formed in a substantially disc shape that is slightly larger than the through hole  21 A formed at the central portion (on the central axis C) of the guide  20  described above, and two hooking pins  43  are formed so as to protrude in the axial direction on an outer surface of the rotating cam  40  facing the inside of the through hole  21 A of the guide  20 . As shown in  FIGS. 2 and 6 , an inner end portion  51  of the lock spring  50  to be described later is hooked on each of the hooking pins  43  described above in a manner of being sandwiched therebetween, so as to be integrally fixed. Further, on an inner surface of the rotating cam  40  described above facing the offset surface portion  30 B of each pole  30 , three pull-in pins  42  which are set to be respectively inserted into corresponding pull-in holes  33  formed in each pole  30  are formed to protrude in the axial direction. 
     The rotating cam  40  described above is assembled to the guide  20  described above in a state of being elastically supported via the lock spring  50 . That is, from the state of being set in the cam accommodating groove  24 B of the guide  20  described above, the rotating cam  40  is assembled to the guide  20  in a state of being elastically supported via the lock spring  50  by setting the lock spring  50  in the through hole  21 A of the guide  20 , in a manner that the inner end portion  51  of the lock spring  50  is hooked between the hooking pins  43  projecting from the outer surface of the rotating cam  40  facing the inside of the through hole  21 A of the guide  20 , and the outer end portion  52  of the lock spring  50  is hung in the hanging hole  21 Aa extending from the through hole  21 A of the guide  20 . 
     According to such an assembling, as shown in  FIG. 9 , the rotating cam  40  is supported in a state of being sandwiched in the axial direction between the disc main body  21  of the guide  20  described above and the offset surface portion  30 B of each pole  30  pushed out in a half-blanking shape in the axial direction, and in the radial direction, is provided to be surrounded from the outer side in the radial direction by the pressed surface portion  32 , which is an inner peripheral surface portion of the main body surface portion  30 A of each pole  30 . 
     The rotating cam  40  described above is always in a state of being rotationally biased in the counterclockwise direction shown in  FIG. 10  with respect to the guide  20  by the spring biasing force of the lock spring  50  (see  FIGS. 2 and 6 ) hooked between the rotating cam  40  and the guide  20 . Due to the rotation in the counterclockwise direction by the biasing, the rotating cam  40  is operated by each pressing portion  44  formed to protrude at a plurality of positions in the peripheral direction on the outer peripheral surface portion of the rotating cam  40 , so as to push the pressed surface portion  32  of each pole  30  from the inner side to the outer side in the radial direction. 
     Further, by the operation of pulling up the reclining lever  5  described above with reference to  FIG. 1 , the rotating cam  40  described above is rotated through the operation pin  5 A in the clockwise direction shown in the figure, which is a direction opposite to the biasing direction described above as shown in  FIG. 11 . As a result, the rotating cam  40  is operated to pull each pole  30  inward in the radial direction by the shape in which each pull-in pin  42  inserted into the pull-in hole  33  of each pole  30  moves radially outward of each pull-in hole  33  while moving in the peripheral direction in each pull-in hole  33 . 
     Specifically, the rotating cam  40  described above is configured such that, in a state where each pole  30  is pushed out from the inner side in the radial direction by a rotational force by the spring biasing force of the lock spring  50  and meshed with the inner peripheral teeth  12 A of the ratchet  10  (locked state) as shown in  FIG. 10 , the inner end portion  51  of the lock spring  50  hooked on the hooking pin  43  is positioned in a region in the peripheral direction 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 the above state, the rotating cam  40  receives an action of a biasing force that is eccentric toward the outer side in the radial direction in addition to a rotational biasing force in the counterclockwise direction in the figure by the spring biasing force received from the inner end portion  51  of the lock spring  50 . Even so, when the poles  30  mesh with the inner peripheral teeth  12 A of the ratchet  10 , the rotating cam  40  is supported by the poles  30  and held in the central portion (on the central axis C) of the guide  20  in a centered state. 
     However, in a state where the rotating cam  40  described above is rotated in the clockwise direction shown in the figure against the spring biasing force of the lock spring  50  described above, and each pole  30  does not mesh with the inner peripheral teeth  12 A of the ratchet  10  as shown in  FIG. 11 , due to a biasing action in an eccentric direction received from the inner end portion  51  of the lock spring  50  described above, the rotating cam  40  is rotated in the clockwise direction shown in the figure in a manner of sliding on the support surfaces  23 B on an inner peripheral side of two guide walls M 1  while being pressed against the support surfaces  23 B of these two guide walls M 1  as shown in  FIG. 16 . At this time, unlike the other two guide walls M 1 , one remaining guide wall M 2  is formed in such a manner that a slight gap T in the radial direction is set between the outer peripheral surface of the rotating cam  40  described above and the guide wall M 2 . 
     According to such a configuration, as shown in  FIG. 16 , in the two guide walls M 1  against which the rotating cam  40  is pressed by the biasing action of the lock spring  50 , while the rotating cam  40  is properly supported so as not to move in an axial displacement direction (eccentric direction), the rotating cam  40  properly escapes the movement when a shape is rattled in a certain direction of the one remaining guide wall M 2  with these two guide walls M 1  as a fulcrum, so that the rotating cam  40  can be smoothly slid and rotated in a releasing direction without eccentricity. 
     (Outer Peripheral Ring  60 ) 
     As shown in  FIGS. 4 and 5 , the outer peripheral ring  60  is formed into a substantially cylindrical shape with a hollow disc-shaped seat by punching one thin plate material into a ring shape, and drawing an outer peripheral portion of the punched hollow disc into a cylindrical shape protruding in the plate thickness direction (axial direction). As a result, the outer peripheral ring  60  has a hollow disc-shaped flange portion  62  that faces a surface in the axial direction, and a coupling portion  61  that protrudes in a substantially cylindrical shape in the axial direction along an outer peripheral edge portion of the flange portion  62 . 
     Specifically, the outer peripheral ring  60  described above is formed by pushing out the coupling portion  61  described above from an outer peripheral portion of the flange portion  62  in a shape protruding in two steps in the axial direction, so as to be formed in a stepped cylindrical shape having an inner and outer two-step cylindrical shape in which a stepped portion  63  that is smaller in the axial direction than the coupling portion  61  and protrudes in a substantially cylindrical shape is formed on an inner peripheral side of the coupling portion  61 . After the three poles  30 , the rotating cam  40 , and the lock spring  50  are set on the guide  20  described above and the guide  20  and the ratchet  10  are assembled, the assembled unit is set inside the cylindrical inner portion and the coupling portion  61  is welded to the guide  20 , so that the outer peripheral ring  60  described above is mounted over outer peripheral portions of the ratchet  10  and the guide  20 . 
     Specifically, the unit described above is set to be assembled inside the cylindrical inner portion from the ratchet  10  first, so that as shown in  FIGS. 9 and 15 , the outer peripheral ring  60  described above is set in such a manner that an end portion on the inner side in the radial direction of the flange portion  62  is abutted against an inclined surface  13 G that is obliquely directed outward in the radial direction and formed on the outer side surface portion in the axial direction of the intermediate cylindrical portion  13  of the ratchet  10  over substantially the entire peripheral direction. With such a setting, the cylindrical portion  22  of the guide  20  is set in the cylindrical coupling portion  61  of the outer peripheral ring  60  so as to be fitted therein. 
     Therefore, after the above setting, the coupling portion  61  of the outer peripheral ring  60  is coupled to the cylindrical portion  22  of the guide  20  fitted therein by laser welding from the outer peripheral side, so that the outer peripheral ring  60  is mounted over the outer peripheral portions of the ratchet  10  and the guide  20 . The inclined surface  13 G formed on the outer side surface portion of the intermediate cylindrical portion  13  of the ratchet  10  described above is formed over the entire area of the ratchet  10  in the peripheral direction so as to draw a prefixed cone shape around the central portion (on the central axis C) of the ratchet  10 . 
     According to such an assembling, the outer peripheral ring  60  is integrally coupled to the guide  20  described above, so that the ratchet  10  is held with respect to the guide  20  with the play being filled in the axial direction and the radial direction by the flange portion  62 . Specifically, the outer peripheral ring  60  described above is set in a state where the flange portion  62  thereof is abutted against the inclined surface  13 G of the ratchet  10  in the axial direction, and the coupling portion  61  is welded and assembled to the cylindrical portion  22  of the guide  20  that is assembled to the ratchet  10  and positioned in the axial direction. As a result, the outer peripheral ring  60  is in a state in which the ratchet  10  is loosened in the axial direction between the flange portion  62  and the disc main body  21  of the guide  20 , and the ratchet  10  is supported with respect to the guide  20  such that the ratchet  10  can be smoothly rotationally moved when unlocked without rattling in the axial direction and the radial direction. 
     (Summary) 
     As described above, according to the device  4 , in the coupling region A 4  (fourth region) coupled with the seat frame  2 F of the outer side surface portion of the ratchet  10 , a portion corresponding to the other region A 3  (third region) of the protruding portion  13  has the expansion surface portion  11 B that is wider outward in the radial direction than a portion corresponding to the free region A 2  (second region). Therefore, the device  4  can expand the portion where the ratchet  10  is coupled to the seat frame  2 F to the outer side in the radial direction as compared with a seat reclining device in related art. 
     Furthermore, according to the device  4 , a wide space in which a space around both ends of the dowels  14  (projections) in the peripheral direction and a space on the outer side in the radial direction of the dowels  14  are continuous can be assigned in the coupling region A 4  (fourth region). Therefore, it is possible to assign a wider area where the ratchet  10  is coupled to the seat frame  2 F. 
     (Other Embodiments) 
     Modes for carrying out the present invention has been described with one embodiment, but the present invention can be carried out in various modes other than the above embodiment. For example, the vehicle seat reclining device of the present invention can be applied to not only a seat other than a right seat of an automobile, but also to a seats for vehicles other than automobiles such as trains, and seats provided for various vehicles such as aircraft and ships. Further, the vehicle seat reclining device described above is configured such that a seat back is connected to a seat cushion in a state where a backrest angle can be adjusted, and may also be configured such that the seat back is connected to a base such as a bracket fixed to the vehicle body side in a state where the backrest angle can be adjusted. 
     Further, the vehicle seat reclining device may be configured such that the ratchet is coupled to a member such as a seat cushion that is fixed to the vehicle body side, and the guide is coupled to the seat back. Further, the plurality of poles forming the lock mechanism of the vehicle seat reclining device may be provided by arranging two or four or more in the peripheral direction. The arrangement of each pole in the peripheral direction is not limited to being evenly arranged, but may be arranged to be offset. 
     Further, the cam that operates to push each pole outward in the radial direction may be of a type that pushes each pole outward in the radial direction by rotation, or may be of a type that slides each pole in the radial direction so as to push out each pole in a radial direction intersecting the sliding direction (see JP-A-2015-227071). The operation of pulling back each pole inward in the radial direction may be performed by a member separate from the cam, such as a release plate (see the same publication). 
     Further, the coupling region which is abutted against and coupled to the seat frame of the ratchet may be abutted against and coupled to the seat frame without the dowel. 
     Here, characteristics of the embodiment of the vehicle seat reclining device  4  according to the present invention described above will be briefly summarized in the following [1] and [2]. 
     [1] 
     A vehicle seat reclining device ( 4 ) including: 
     a disc-shaped ratchet ( 10 ) and a disc-shaped guide ( 20 ), the ratchet ( 10 ) and the guide ( 20 ) being coaxially assembled in a relatively rotatable manner; 
     a lock mechanism provided between the ratchet ( 10 ) and the guide ( 20 ), and capable of restricting relative rotation between the ratchet ( 10 ) and the guide ( 20 ); and 
     a retaining ring ( 60 ) retaining an assembled state of the ratchet ( 10 ) and the guide ( 20 ), 
     in which the lock mechanism includes: a plurality of poles ( 30 ) supported by the guide ( 20 ) movably in a radial direction, the plurality of poles ( 30 ) meshing with the ratchet ( 10 ) when moving outward in the radial direction so as to restrict the relative rotation between the ratchet ( 10 ) and the guide ( 20 ); and a cam ( 40 ) for moving the plurality of poles ( 30 ) outward or inward in the radial direction, 
     in which the ratchet ( 10 ) has: an annular protruding portion ( 13 ) where an outer peripheral portion of the ratchet ( 10 ) protrudes to one side in an axial direction; and an outer side surface portion configured to face a seat frame ( 2 F) on the other side in the axial direction of the ratchet ( 10 ), 
     in which the protruding portion ( 13 ) has: a first region (A 1 ) in which a specific pole ( 30 ) of the plurality of poles ( 30 ) is allowed to move outward in the radial direction and to mesh with the ratchet ( 10 ); a second region (A 2 ) in which the specific pole ( 30 ) is prevented from moving outward in the radial direction and from meshing with the ratchet ( 10 ); and a third region (A 3 ) in which another pole ( 30 ) is located when the specific pole ( 30 ) is in the second region (A 2 ), the first region (A 1 ), the second region (A 2 ), and the third region (A 3 ) being arranged in a peripheral direction, 
     in which the outer side surface portion has a fourth region (A 4 ) configured to be in contact and coupled with the seat frame ( 2 F), and 
     in which the protruding portion ( 13 ) has a shape in which the third region (A 3 ) extends further outward in the radial direction than the second region (A 2 ), so that the fourth region (A 4 ) has a shape in which a portion of the fourth region (A 4 ) which corresponds to the third region (A 3 ) is wider outward in the radial direction than a portion of the fourth region (A 4 ) which corresponds to the second region (A 2 ). 
     [2] 
     The vehicle seat reclining device ( 4 ) according to [ 1 ], 
     in which the outer side surface portion has a projection ( 14 ) protruding toward the other side in the axial direction so as to be fitted into the seat frame ( 2 F), the projection ( 14 ) being provided on the fourth region (A 4 ), and 
     in which the projection ( 14 ) has a shape in which a length of the projection ( 14 ) in the peripheral direction is equal to or less than a length of the third region (A 3 ) in the peripheral direction. 
     This application is based on Japanese Patent Application No. 2018-031927 filed on Feb. 26, 2018, the contents of which are incorporated herein by reference. 
     INDUSTRIAL APPLICABILITY 
     According to the vehicle seat reclining device of the present invention, it is possible to expand a coupling region of a ratchet to a seat frame. The present invention having this effect is useful for a seat of an automobile or the like, for example. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  seat 
               2  seat back 
               2 F side frame (seat frame) 
               2 Fa fitting hole 
               2 Fb passage hole 
               3  seat cushion 
               3 F reclining plate 
               3 Fa fitting hole 
               3 Fb passage hole 
               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  disc main body 
               11 A through hole 
               11 B expansion surface portion 
               12  cylindrical portion 
               12 A inner peripheral teeth 
               13  intermediate cylindrical portion (protruding portion) 
               13 A region 
               13 B region 
               13 C region 
               13 D first projection 
               13 E second projection 
               13 F escape recess 
               13 G inclined surface 
             A 1  lock region (first region) 
             A 2  free region (second region) 
             A 3  other region (third region) 
             A 4  coupling region (fourth region) 
               14  dowel 
             W welding portion 
               20  guide 
               21  disc main body 
               21 A through hole 
               21 Aa hanging hole 
               21 B dowel 
               21 C play filling pin 
               22  cylindrical portion 
               23  guide wall 
               23 A restriction surface 
               23 B support surface 
               23 C bead portion 
             M 1  guide wall 
             M 2  guide wall 
             T gap 
               24 A pole accommodating groove 
               24 B cam accommodating groove 
               30  pole 
               30 A main body surface portion 
               30 B offset surface portion 
               31  outer peripheral teeth 
               32  pressed surface portion 
               33  pull-in hole 
               34  riding protrusion 
               34 A outer peripheral surface portion 
               34 B inclined surface 
               35  play filling hole 
             P 1  main pole (specific pole) 
             P 2  sub pole (another pole) 
             Q quality control surface 
               40  rotating cam (cam) 
               41  through hole 
               42  pull-in pin 
               43  hooking pin 
               44  pressing portion 
               50  lock spring 
               51  inner end portion 
               52  outer end portion 
               60  outer peripheral ring (retaining ring) 
               61  coupling portion 
               62  flange portion 
               63  stepped portion 
             C central axis