Abstract:
[Problem] The present invention addresses the problem of providing a reclining device in which a pawl moves smoothly, does not slip and locks well. 
     [Solution] A cam part that moves a pawl ( 33 ) in the direction of a locked position is configured from a rotating cam (first cam) ( 31 ) that pushes the pawl ( 33 ) in the direction of the locked position and a cam (second cam) ( 34 ) that is pressed by the rotating cam ( 31 ) and pushes the pawl ( 33 ) in the direction of the locked position while pressing same against a guide ( 25 c). The cam part is configured so that when the pawl ( 33 ) located at the unlocked position moves to the locked position, the cam part initially presses the pawl ( 33 ) with the rotating cam ( 31 ), and when the pawl ( 33 ) is at the locked position, presses the pawl ( 33 ) with the cam ( 34 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a reclining device that allows and restricts tilting of a seat back of a seat with respect to a seat cushion. 
       BACKGROUND ART 
       [0002]    It will be described with reference to  FIG. 9  and  FIG. 10 .  FIG. 9  is a configuration view of a seat, and  FIG. 10  is a side view of a reclining device of the seat for a vehicle of the prior art. 
         [0003]    As shown in  FIG. 9 , a seat  101  includes a seat cushion  102  supporting buttocks of a seated person, and a seat back  103  provided to be tiltable with respect to the seat cushion  102  in a forward and rearward direction and to support a back of the seated person. Reference numeral  104  is a reclining device provided on a rotational axis of the tilting of the seat back  103  to allow and restrict the tilting of the seat back  103 . 
         [0004]    The reclining device  104  will be described with reference to  FIG. 10 . In the drawing, a hinge pin  131  is provided to stand on a lower arm plate (second member)  130 , which is attached to a rear portion of a lower arm provided at a seat cushion side. A ratchet plate (first member)  132  is rotatably arranged on the hinge pin  131  and is fixed to an upper arm provided at a seat-back side. A lower portion of the latchet plate  132  is provided with internal teeth  133  in a circumferential direction of a circle centered on the hinge pin  131 . 
         [0005]    A pawl  134  is arranged between the lower arm plate  130  and the latchet  132 , and it is formed with external teeth  135  which can be engaged with the internal teeth  133  of the latchet plate  132 . 
         [0006]    The lower arm plat  130  is provided with guides  136  and  137  for guiding the pawl  134  in a radial direction of a circle centered on the hinge pin  131 . 
         [0007]    A release arm  142  rotatably installed in the hinge pin  131  is formed with a elongate hole  143 , into which a pin  140  of the pawl  134  penetrating an arc-shaped elongate hole  132   e  which is formed in the latchet plate  132  and centered on the hinge pin  131  is fitted. The elongate hole  143  is configured to have a portion close to the internal teeth  133  of the latchet plate  132 , and a portion spaced apart from the internal teeth  133 , and when the release arm  142  rotates, the pawl  134  moves in the radial direction of the circle centered on the hinge pin  131 , and then the external teeth  135  of the pawl  134  is engaged with or disengaged from the internal teeth  133  of the latchet plate  132 . 
         [0008]    A first cam  144  is rotatably attached to the hinge pin  131 . 
         [0009]    A second cam  141  is provided between the first cam  144  and an inclined face of the pawl  134 , which is opposite to its side formed with the external teeth  135 . The inclined face of the pawl  134  is a face intersecting with the radial direction of the circle. 
         [0010]    The release arm  142  is applied with an urging force by a spring  150  in such a direction that the first cam  144  presses the pawl  134  via the second cam  141 , and the spring  150  has one end portion locked to the release arm  142  and the other end portion locked to the lower arm plate  130 . 
         [0011]    An end face of the hinge pin  131  is formed with a groove, and an inner end portion of a spiral spring  156 , of which an outer end portion is locked to the pin  155  provided to stand on the latchet plate  132 , locked to the groove, so that the latchet plate  132  (upper arm) is urged in a forward tilting direction. 
         [0012]    Next, the operation of the configuration will be described. The state shown in  FIG. 10  is a state where the first cam  144  presses the pawl  134  via the second cam  141  which contacts the inclined face of the first cam  144 , the guide  137 , and the pawl  134 , respectively, and the external teeth  135  of the pawl  134  are engaged with the internal teeth  133  of the latchet plate  132  to restrict the rotation of the latchet plate  132 , so that the reclining (tilting) of the seat back is locked and. 
         [0013]    In this state, when the release arm  142  located at a position indicated by a solid line is rotated to a position indicated by a two-dot chain line against the urging force of the spring  150 , the first cam  144  engaged with the release arm  142  is rotated in the same direction, and thus the state of pressing the pawl via the second cam  141  of the first cam  144  is released. 
         [0014]    The pawl  134  having the pin  140  which is fitted into the elongate hole  143  of the release arm  142  is also guided by the guides  136  and  137  to move in the direction of the hinge pin  131 , and thus the engaging state of the external teeth  135  of the pawl  134  and the internal teeth  133  of the latchet plate  132  is released, so that the latchet plate  132 , i.e. the seat back, is to be in a tiltable state. 
         [0015]    When the seated person achieves a desired tilting angle by tilting the desired seat back, one releases the operation force of the release arm  142 . Then, the release arm  142  is returned from the position indicated by the two-dot chain line to the position indicated by the solid line by the urging force of the spring  150 , and the first cam  144  is rotated in a direction contrary to the above-described direction to be returned in the state in  FIG. 10  (e.g., see Patent Document 1). 
       CITATION LIST 
     Patent Literature 
       [0016]    Patent Document 1: JP-B-H08-019442 
       SUMMARY 
     Technical Problem 
       [0017]    However, according to the reclining device having the above-described configuration, as the second cam  141  presses the inclined face of the pawl  134 , the pawl  134  is always pressed against the guide  136 . Accordingly, although there is an effect that rattling between the pawl  134  and the guide  136  when locking is eliminated, and the decrease in locking strength due to the tilting of the pawl  134  is suppressed, when the pawl  134  located at the unlocked position moves to the locked position, there is a problem in that the pawl  134  does not smoothly move. 
         [0018]    Additionally, since the pawl  134  does not smoothly move, there is another problem causing a phenomenon that the external teeth  135  cannot be engaged with the internal teeth  133  (hereinafter referred to as tooth jumping) is caused. 
         [0019]    The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a reclining device, in which a pawl moves smoothly, the tooth jumping does not occur, and thus a locking operation is favorably performed. 
       Solution to Problem 
       [0020]    In order achieve at least one of the above objects, a reclining apparatus according to one aspect of the present invention including: a first member, which is provided with internal teeth along a circumferential direction thereof; a second member, which is stacked on the first member and is provided to be rotatable relative to the first member in the circumferential direction; a pawl, which is movably provided on the second member and is provided with external teeth formed to engage with the internal teeth; a guide, which is formed in the second member to guide the pawl between a locked position in which the internal teeth are engaged with the external teeth and an unlocked position in which the internal teeth are not engaged with the external teeth; and a cam part provided between the first member and the second member to move the pawl in a position of the locked position, wherein the cam part is configured by: a first cam rotatably provided on an axis of the relative rotation and pressing the pawl in the direction of the locked position; and a second cam provided between the first cam and the pawl and pressed by the first cam to press the pawl in the direction of the locked position while pressing the pawl against the guide, wherein, when the pawl located at the unlocked position moves to the locked position, the cam part initially presses the pawl with the first cam and then presses the pawl with the second cam in a state where the pawl is at the locked position. 
         [0021]    In the reclining device, it is preferable that when the pawl located at the unlocked position moves to the locked position, the cam part initially presses the pawl only with the first cam, then presses the pawl with the first cam and the second cam between the unlocked position and the locked position, and thus presses the pawl only with the second cam in the state where the pawl is at the locked position. 
         [0022]    Additionally, it is preferable that when the external teeth and the internal teeth start to engage with each other, the cam part presses the pawl with the second cam. 
         [0023]    Herein, the phrase “the external teeth and the internal teeth start to engage with each other” means that an addendum circle of the external teeth starts to lap an addendum circle of the internal teeth. 
         [0024]    Additionally, it is preferable that a gap is formed between the first cam and the pawl in the state where the pawl is located at the locked position and is capable of contacting contacts the first cam when the pawl is tilted. 
       EFFECT OF THE INVENTION 
       [0025]    According to the present invention, the cam part includes the first cam rotatably provided on an axis of the relative rotation and pressing the pawl in the direction of the locked position, and the second cam provided between the first cam and the pawl and pressed by the first cam to press the pawl in the direction of the locked position while pressing the pawl against the guide. When the pawl located at the unlocked position moves to the locked position, the cam part initially presses the pawl with the rotating cam. Therefore, when the pawl located at the unlocked position moves to the locked position, frictional resistance is small, and thus the pawl moves smoothly, so that the tooth jumping does not occur, and the locking operation is favorably performed. 
         [0026]    Further, since the pawl is pressed with the cam in the state where the pawl is at the locked position, the rattling between the pawl and the guide is eliminated, and the decrease in locking strength due to the tilting of the pawl is prevented. 
         [0027]    Other effects of the present invention will be more apparent from the following detailed description of the invention and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  is an exploded perspective view showing a reclining device of the present embodiment. 
           [0029]      FIG. 2  is a perspective view showing a ratchet in  FIG. 1  as viewed from an arrow II. 
           [0030]      FIG. 3  is a cross-sectional view taken along the section line in  FIG. 2 . 
           [0031]      FIG. 4  is a cross-sectional view taken along the section line IV-IV in  FIG. 3  to explain a state where pawls are at a locked position (state where a rotating cam is rotated by 28.5 degrees in a full open state). 
           [0032]      FIG. 5  is a view explaining the full open state in  FIG. 4  (state where the pawls are at an unlocked position). 
           [0033]      FIG. 6  is a view explaining the state where the rotating cam is rotated by 12.8 degrees from the full open state in  FIG. 5 . 
           [0034]      FIG. 7  is a view explaining the state where the rotating cam is rotated by 15.3 degrees from the full open state in  FIG. 5 . 
           [0035]      FIG. 8  is a view explaining the state where the rotating cam is rotated by 20.4 degrees from the full open state in  FIG. 5 . 
           [0036]      FIG. 9  is a configuration view of a seat. 
           [0037]      FIG. 10  is a side view of a reclining device of the seat for a vehicle of the prior art. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0038]    Next, an embodiment of the present invention will be described to the accompanying drawings.  FIG. 1  is an exploded perspective view illustrating a reclining device of the present embodiment.  FIG. 2  is a perspective view illustrating a ratchet in  FIG. 1  as viewed from an arrow II.  FIG. 3  is a cross-sectional view taken along the section line in  FIG. 2 .  FIG. 4  is a cross-sectional view taken along the section line IV-IV in  FIG. 3  to illustrate a state where a pawls are at a locked position (state where a rotating cam is rotated by 28.5 degrees in a full open state).  FIG. 5  is a view explaining the full open state in  FIG. 4  (state where the pawls are at an unlocked position).  FIG. 6  is a view explaining the state where the rotating cam is rotated by 12.8 degrees from the full open state in  FIG. 5 .  FIG. 7  is a view explaining the state where the rotating cam is rotated by 15.3 degrees from the full open state in  FIG. 5 .  FIG. 8  is a view explaining the state where the rotating cam is rotated by 20.4 degrees from the full open state in  FIG. 5 . 
         [0039]    First, the configuration of the reclining device according to the present embodiment will now be described with reference to  FIGS. 1 to 4 . 
         [0040]    The reclining device according to the present embodiment is provided on a rotational axis of the tilting of the seat back  103 , similarly to the reclining device  104  in  FIG. 9 . 
         [0041]    In  FIG. 1 , a ratchet (first member)  21  provided on a side of the seat back is obtained by half-blanking a disk-shaped plate material using a press working and has a bottomed cylindrical shape, in which one face is opened. Internal teeth  23  are formed on an inner cylindrical face of the ratchet  21  along the circumferential direction overall. A through-hole  21   b  is formed in the center of a bottom portion  21   a.    
         [0042]    A base plate (second member)  25  provided on a side of a seat cushion is also obtained by half-blanking on a disk-shaped plate material by a press working and has a bottomed cylindrical shape, one side of which is an open side. A diameter of a bottom portion  25   a  of the bottomed cylinder is set to be slightly larger than an outer diameter of the ratchet  21 . Also, the ratchet  21  is fitted into the bottom portion  25   a , and the base plate  25  and the ratchet  21  are able to relatively rotate. Also, a through-hole  25   b  is formed in the center of the base plate  25 . 
         [0043]    Further, as shown in  FIG. 3 , an outer circumferential portion of the ratchet  21  and an outer circumferential portion of the base plate  25  are clamped by an outer circumferential ring  27  having a ring shape, so that the ratchet  21  and the base plate  25  are held to be able to relatively rotate, without being separated in a direction of a relative rotation axis (a reference numeral O in  FIG. 1 ). 
         [0044]    Returning to  FIG. 1 , a rotating cam  31  (fist cam) is disposed in a space defined by the bottom portion  21   a  of the ratchet  21  and the bottom portion  25   a  of the base plate  25 . A non-circular (oval-track) through-hole  31   a  is formed in the center of the rotating cam  31 . 
         [0045]    Three pawls  33  are arranged on the base plate  25  to be located outside the rotating cam  31 . The pawls  33  have external teeth  57  to be able to engage with the internal teeth  23 . 
         [0046]    Then, as shown in  FIG. 4 , the base plate  35  is provided with guides  25   c  for guiding the respective pawls  33  in a radial direction of the relative rotation. Therefore, each pawl  10  is movable in the radial direction of the relative rotation. 
         [0047]    Also, a cam (second cam)  34  is disposed among each pawl  33 , the rotating cam  31  and each guide  25   c.    
         [0048]    Returning to  FIG. 1 , a recess  33   c  extending in a direction intersecting with the radial direction of the relative rotation, and a hook portion  33   a  are formed on a face opposite to a face, on which the external tooth  57  is formed, of each pawl  33 . 
         [0049]    Meanwhile, three hook portions  31   b  to be entered into the recess  33   c  of each pawl  33  are formed on a circumferential portion of the rotating cam  31 . Also, a lock face  33   b,  to which each cam  34  can be contacted, is formed on the face opposite to the face, on which the external tooth  57  is formed, of each pawl  33 . The lock face  33   b  intersects with the radial direction of the relative rotation, and it is set as a face generating a force causing the pawl  33  to be pressed against the guide  25   c  and a force causing the pawl  33  to move in an engaging direction (radial direction of the relative rotation) of the external teeth  57  and the internal teeth  23 , when it is pressed by the cam  34 . 
         [0050]    Additionally, the hook portion  33   a  of each pawl  33  is formed with a rotating cam contacting portion  33   d  which can contact a cam contacting portion  31   c  formed on the rotating cam  31  at a portion except for the hook portion  31   b.    
         [0051]    Also, as shown in  FIG. 4 , when the rotating cam  31  is rotated in one direction (a counter-clockwise direction in the figure), the hook portions  31   b  of the rotating cam  31  press the cams  34 , and the cams  34  press the guides  25   c  and the lock faces  33   b  of the pawls  33 , so that the pawls  33  are moved in a direction away from the relative rotation axis to be positioned at a locked position, where the external teeth  57  of the pawls  33  are engaged with the internal teeth  23  of the ratchet  21 . 
         [0052]    In this instance, a gap G (0.2 mm in the present embodiment) is formed between the cam contacting portions  31   c  of the rotating cam  31  and the rotating cam contacting portions  33   d  of the pawls  33 . 
         [0053]    According to the present embodiment, an unlock holding mechanism configured by three arc-shaped guides  71 , which is formed along a circumferential direction of an inner cylindrical face of the ratchet  21  and is located at a side of the bottom portion  21   a  than the internal teeth  23 , and protrusions  73 , which is respectively formed on a face of each pawl  33  opposite to the bottom portion  21   a  of the ratchet  21  by half-blanking, is provided. 
         [0054]    Then, when the protruding portions  73  of the respective pawls  33  contact the arc-shaped guides  71 , the pawls  33  are hold at the unlocked position in which the external teeth  57  are unengaged with the internal teeth  23  of the latchet  21 . 
         [0055]    An operation shaft  77 , which has a non-circular (oval-track) sectional shape and rotate integrally with the rotating cam  31 , is engaged in the non-circular through-hole  31   a  of the rotating cam  31 . A flange portion  75 , which formed on an outer circumferential face of the operation shaft  77  along the circumferential direction overall, protrudes in the radial direction of the operation shaft  77  and contacts to the bottom portion  21   a  of the ratchet  21 , to restrict the operation shaft  77  from being tilted in any direction with respect to the bottom portion  21   a  of the ratchet (first member)  21 . The flange portion  75  according to the present embodiment is configured as one continuous flange which is formed over the circumferential direction of the outer circumferential face of the operation shaft  77 . However, the flange portion  75  may be configured as a plurality of non-continuous flanges. In this case, to restrict the operation shaft  77  from being tilted in any direction with respect to the bottom portion  21   a  of the ratchet (first member)  21 , it is sufficient that an angle in the circumferential direction of a gap between the adjacent flanges be less than 180 degrees. 
         [0056]    Further, the operation shaft  77  is set to have a height exposed from the through-hole  25   b  of the base plate  25  to the outside. 
         [0057]    Additionally, a spiral spring  79  formed by working on an elongated spring plate material in a spiral shape is disposed in the through-hole  25   b  of the base plate  25 . An inner end  79   a  of the spiral spring  79  is locked on the operation shaft  77  and an outer end is locked in a notch  25   d,  which is formed in a circumferential face of the through-hole  25   b  of the base plate  25 . Due to an urging force of the spiral spring  79 , the pawls  33  are urged in a direction toward the locked position via the rotating cam  31 . 
         [0058]    Here, the operation of the reclining device according to the present embodiment will be described with reference to  FIGS. 4 to 8 . 
         [0059]    As shown in  FIG. 4 , when an operation force is not exerted on the rotating cam  31 , the rotating cam  31  is rotated in one direction (counterclockwise direction) by the urging force of the spiral spring  79 , and thus the hook portions  31   b  of the rotating cam  31  are pressed against the lock faces  33   b  of the pawls  33  via the cam  34 . As described above, when the lock faces  33   b  of the pawls  33  are pressed, a force causing the pawls  33  to move in the engaging direction (radial direction of the relative rotation) of the external teeth  57  and the internal teeth  23  is generated, so that the pawls  33  are at the locked position in which the external teeth  57  of the pawls  33  are engaged with the internal teeth  23  of the ratchet  21 . Therefore, the relative rotation between the ratchet  21  and the base plate  25  is restricted, and thus the seat back is to be in the state where it cannot rotate with respect to the seat cushion (the lock state). 
         [0060]    Further, a force causing the pawls  33  to be pressed against the guides  25   c  is also generated, so that the rattling between the pawls  33  and the guides  25   c  is eliminated. 
         [0061]    When the rotating cam  31  (operating shaft  77 ) is rotated in other direction (clockwise direction in the drawing) against the urging force of the spiral spring  79  from the state where the pawls  33  are at the locked position, the hook portions  31   b  of the rotating cam  31  enter the concave portions  33   c  of the pawls  33 , they are engaged with the hook portions  33   a  of the pawls  33 , (they are pressed against the inner wall of the concave portions  33   c  at the rotational center side of the relative rotation thereof), and then the pawls  33  are pulled in the direction close to the axis of the relative rotation, and thus the pawls  33  are at the unlocked position (full open state), shown in 
         [0062]      FIG. 5 , in which the engaging state of the external teeth  57  and the internal teeth  23  of the latchet  21  is released. Accordingly, the relative rotation between the latchet  21  and the base plate  25  is possible, so that the seat back is to be rotatable with respect to the seat cushion. 
         [0063]    When the operation force is released from the rotating cam  31  in the full open state shown in  FIG. 5 , the rotating cam  31  is rotated in the counterclockwise direction by the urging force of the spiral spring  79 . 
         [0064]    When the rotating cam  31  is rotated by 12.8 degrees in the counterclockwise direction, as shown in  FIG. 6 , the cam contacting portions  31   c  of the rotating cam  31  contact the rotating cam contacting portions  33   d  of the pawls  33  to press the pawls  33  in the lock direction. When the cam contacting portions  31   c  contact the rotating cam contacting portions  33   d,  the rotating cam contacting portions  33   d  of the pawls  33  are configured to generate little force causing the pawls  33  to be pressed against the guides  25   c,  and they generate only force causing the pawls  33  to move in the engaging direction (radial direction of the relative rotation) of the external teeth  57  and the internal teeth  23 . 
         [0065]    Next, when the rotating cam  31  is rotated by 15.3 degrees, as shown in  FIG. 7 , the cam contacting portions  31   c  of the rotating cam  31  contact the rotating cam contacting portions  33   d  of the pawls  33  to press the pawls  33  in the lock direction. Simultaneously, the hook portions  31   b  of the rotating cam  31  start to press the cams  34 , and thus the cams  34  start to move in the direction of the lock faces  33   b  of the pawls  33 . At that time, the cams  34  do not contact the lock faces  33   b  of the pawls  33 . 
         [0066]    Additionally, when the rotating cam  31  is rotated by 20.4 degrees, as shown in  FIG. 8 , the cam contacting portions  31   c  of the rotating cam  31  contact the rotating cam contacting portions  33   d  of the pawls  33  to press the pawls  33  in the lock direction. Simultaneously, the hook portions  31   b  of the rotating cam  31  start to press the lock faces  33   b  of the pawls  33  via the cams  34 . That is, the rotating cam  31  and the cams  34  configures the cam part for pressing the pawls  33  to move the pawls  33  in the direction of the locked position. In the present embodiment, when the rotating cam  31  is rotated more than 20.4 degrees, an addendum circle of the external teeth  57  starts to lap an addendum circle of the internal teeth  23 . That is, the external teeth  57  and the internal teeth  23  start to engage with each other. 
         [0067]    When the rotating cam  31  is rotated more than 20.4 degrees, the cam contacting portions  31   c  of the rotating cam  31  start to separate from the rotating cam contacting portions  33   d  of the pawls  33 , but the hook portions  31   b  of the rotating cam  31  start to press the lock faces  33   b  of the pawls  33  via the cams  34 . When the rotating cam  31  is rotated by 28.5 degrees, the pawls  33  are pressed to the locked position shown in  FIG. 4 , so that the external teeth  57  of the pawls  33  and the internal teeth  23  of the latchet  21  are returned to the lock state where they are engaged with each other without rattling. 
         [0068]    Between a first lock (FL) state and a forward falling (FF) state shown in  FIG. 9 , even though the operation force of the operating shaft  77  is released by the above-described unlock holding mechanism, the pawls  33  are hold at the unlocked position, so that the seat back is to be rotatable, without operating the operating shaft  77 . That is, between the first lock (FL) state and the forward falling (FF) state shown in  FIG. 9 , the protruding portion  73  of each pawl  33  is positioned on the arc-shaped guide  71 , the pawls  33  are hold at the unlocked position, even though the operation force is released from the operating shaft  77 . Therefore, the relative rotation between the latchet  21  and the base plate  25  is to be possible. 
         [0069]    In this configuration of the reclining device as described above, the following effects are achieved. 
         [0070]    (1) When the pawls  33  located at the unlocked position move to the locked position, the cam part initially presses the pawls  33  with the rotating cam  31 . Therefore, when the pawls  33  located at the unlocked position move to the locked position, frictional resistance is to be small, and thus the pawls move smoothly, the tooth jumping does not occur, and thus the locking operation is favorably performed. 
         [0071]    Further, since the pawls  33  are pressed with the cam  34  in the state where the pawls  33  are at the locked position, the rattling between the pawls  33  and the guides  25   c  is eliminated, and the decrease in locking strength due to the tilting of the pawls  33  is prevented. 
         [0072]    (2) When the pawls  33  located at the unlocked position move to the locked position, the cam part initially presses the pawls  33  only with the rotating cam  31 , then presses the pawls  33  with the rotating cam  31  and the cam between the unlocked position and the locked position, and thus the cam part presses the pawls only with the cam  34  in the state where the pawls  33  are at the locked position, so that the pawls  33  are always pressed with the rotating cam  31  or the cam  34 , so that the pawls  33  move reliably. 
         [0073]    Further, as compared with the cam pressing the pawls  33  is instantaneously switched from the rotating cam  31  to the cam  34 , since the mechanism in which the pawls  33  are pressed by the rotating cam  31  and the cam  34  between the unlocked position and the locked position, it is possible to largely set an allowable error in precision of parts of the rotating cam  31 , the cam  34 , and the pawls  33 . 
         [0074]    (3) When the external teeth  57  and the internal teeth  23  start to engage with each other, the pawls  33  are pressed with the cam  34 , and thus it is possible to further prevent the tooth jumping. 
         [0075]    (4) In the state where the pawls  33  are at the locked position, since the gap (0.2 mm in the present embodiment) is provided between the cam contacting portion  31   c  of the rotating cam  31  and the rotating cam contacting portion  33   d  of the pawl  33 , a large force acts on the reclining device. Therefore, even though the pawls  33  contacting the cam  34  are inclined, the pawls  33  contact the rotating cam  31 , and thus the lock state is retained without largely inclining the pawls  33 . 
         [0076]    The present invention is not limited to the above-described embodiment. In the above-described embodiment, the ratchet  21  is provided on the seat-back side and the base plate  25  is provided on the seat cushion side in the above-described embodiment. In contrast, the base plate  25  may be provided on a side of the seat back, and the ratchet  21  may be provided on the seat cushion. 
         [0077]    Additionally, in the case where the pawls are inclined in the state where the pawls  33  are at the locked position, the cam contacting portions  31   c  of the rotating cam  31  and the rotating cam contacting portions  33   d  of the pawls  33  contact with each other, thereby preventing the pawls  33  from being largely inclined, in above-described embodiment. However, other portions of the pawls  33  and the rotating cam  31  may be brought into contact. 
         [0078]    Further, the present invention can be properly modified or revised without being deviated from the thoughts and the claims of the invention. 
       REFERENCE NUMERALS LIST 
       [0000]    
       
           21 : Latchet 
           23 : Internal teeth 
           25 : Base plate 
           31 : Rotating cam (first cam) 
           31   b : Hook portion 
           33 : Pawl 
           33   d : Cam contacting portion 
           33   c : Concave portion 
           34 : Cam (second cam) 
           57 : External teeth