Abstract:
A vehicle seat is provided comprising a seat back frame having right and left side frames, a headrest for supporting a head of a seat occupant, and a back-and-forth movable body provided inside a backrest that is positioned at a rear of the seat occupant, wherein a backward movement of the back-and-forth movable body forwardly moves the headrest to support the head of the seat occupant. The back-and-forth movable body is attached to each side frame through a link member and is provided with a backward protrusion protruding backward, and the backward protrusion extends laterally.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 12/279,766, filed Jun. 18, 2009, which is a PCT national stage entry of international patent application no. PCT/JP2005/13468, filed Jul. 22, 2005. The contents of these applications are herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a coupling mechanism for a headrest of a vehicle seat, and more particularly to a coupling mechanism for moving the headrest forward when a forward external force acts on a car body as a result of rear end collisions or the like. 
         [0003]    Conventionally, there is known from Japanese Patent Application Laid-Open No. 10-119619 a vehicle seat having a headrest provided in a backrest, a movable member provided inside of the backrest, and a coupling mechanism for coupling the headrest and the movable member mechanically, in which, when a vehicle seat occupant moves backward relative to the vehicle seat due to rear collisions or the like, the movable member is pushed by the occupant to move backward, and the backward movement of the movable member moves the headrest forward by way of the coupling mechanism. 
         [0004]    The coupling mechanism of the prior art is disposed substantially at the backside of a cushion of the backrest, and thus the cushion performance may be lowered. That is, the coupling mechanism is provided at a position overlapping the vehicle seat occupant in the front-to-back direction, and thus the cushion design is restricted. 
         [0005]    The movable member in the prior art is narrow in its movable range, and the distance of moving the headrest forward is short, and means for compensating for lack of distance is difficult. 
       SUMMARY 
       [0006]    It is hence an object of embodiments of the invention to provide a coupling mechanism for a headrest capable of amplifying the small moving amount of the movable member and transmitting the movement to the headrest. It is another object of embodiments of the invention to provide a coupling mechanism for a headrest capable of amplifying the moving amount of the movable member with a simple configuration. It is still another object of the invention to provide a coupling mechanism for a headrest not interfering with the cushion of the backrest substantially. 
         [0007]    Therefore, a vehicle seat is provided comprising a seat back frame having right and left side frames, a headrest for supporting a head of a seat occupant, and a back-and-forth movable body provided inside a backrest that is positioned at a rear of the seat occupant, wherein a backward movement of the back-and-forth movable body forwardly moves the headrest to support the head of the seat occupant. The back-and-forth movable body is attached to each side frame through a link member and is provided with a backward protrusion protruding backward, and the backward protrusion extends laterally. 
         [0008]    A vehicle seat is also provided comprising a seat back frame having right and left side frames, a headrest for supporting a head of a seat occupant, and a back-and-forth movable body provided inside a backrest that is positioned at a rear of the seat occupant, wherein a backward movement of the back-and-forth movable body forwardly moves the headrest to support the head of the seat occupant. The back-and-forth movable body is attached to each side frame through a link member and is provided with a backward protrusion protruding backward in at least an end part in a vertical direction, and the backward protrusion extends laterally. 
         [0009]    A vehicle seat is also provided comprising a seat back frame having right and left side frames, a headrest for supporting a head of a seat occupant, and a back-and-forth movable body provided inside a backrest that is positioned at a rear of the seat occupant, wherein a backward movement of the back-and-forth movable body forwardly moves the headrest to support the head of the seat occupant. The back-and-forth movable body is attached to each side frame through a link member and is provided with first and second backward protrusions protruding backward, and the first and second backward protrusions extend laterally and are arranged in parallel with each other. 
         [0010]    A vehicle seat is also provided comprising a seat back frame having right and left side frames, a headrest for supporting a head of a seat occupant, and a back-and-forth movable body provided inside a backrest that is positioned at a rear of the seat occupant, wherein a backward movement of the back-and-forth movable body forwardly moves the headrest to support the head of the seat occupant. The back-and-forth movable body is attached to each side frame through a link member, provided with a first backward protrusion protruding backward in an upper end part thereof, and provided with a second backward protrusion protruding backward in a lower end part thereof, and the first and second backward protrusions extend laterally. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    An embodiment of the invention is shown in the following figures. 
           [0012]      FIG. 1  is an overall perspective view of a vehicle seat; 
           [0013]      FIG. 2  is a perspective view showing a backrest frame and a part of a coupling mechanism for a headrest; 
           [0014]      FIG. 3  is a side view of the coupling mechanism for a headrest; 
           [0015]      FIG. 4  is a front view of the backrest frame and the coupling mechanism for a headrest; 
           [0016]      FIG. 5  is a magnified side view of a lower link mechanism of the coupling mechanism; 
           [0017]      FIG. 6  is a sectional view of a first link of the coupling mechanism; 
           [0018]      FIG. 7  is a magnified side view of an upper link mechanism of the coupling mechanism; and 
           [0019]      FIG. 8  is a magnified side view showing the first link elevated from the state in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    An embodiment of the invention will be described with reference to the accompanying drawings. A vehicle seat  1  of the invention has a backrest  2 A, a seat bottom  2 B, and a headrest  3  having a head support  4  is provided in an upper part of the backrest  2 A. A backrest frame  16  of the backrest  2 A has a square frame shape, including a pair of side frames  40 , each having an inward extension  40   a  and outwardly recessed portion  50 , an upper frame  41 , and a lower frame  42 . 
         [0021]    Near the upper frame  41 , an upper movable member  10  (headrest support member) movable laterally to the backrest frame  16  is disposed. Vertical pillar supports  11  for inserting the lower parts of pillars  6  of the headrest  3  are fixed in the movable member  10 . The pillars  6  are supported by the pillar supports  11  to be adjustable in height. The movable member  10  also has an outward extension  12   a , and a forward extension  12   b , as well as a protrusion  14  having an anteroposterior extension, and a forward bent portion  14   a.    
         [0022]    Both right and left sides of the upper movable member  10  are attached to the backrest frame  16  by way of an individual upper link mechanism  15 . Each upper link mechanism  15  has a long first link  17  (downward extension), an arm  18  (second link member), and a second link  23  (first link member) as shown in  FIGS. 2 ,  3  and  7 . The end part of the upper movable member  10  is fixed to an upper part of the first link  17 , and the arm  18  is rotatably pivoted on an L-shaped bracket  20  (bracket, bracket member) fixed in the upper part of the backrest frame  16  by way of a shaft  21  (second link support shaft). An intersection  13  exists between the first link  17  and the forward extension  12   b . The second link  23  is rotatably pivoted on the bracket  20  by way of a shaft  25  (first link support shaft). The leading end of the arm  18  is pivoted on the vertical intermediate position of the first link  17  by way of a shaft  19  (second coupling shaft), and the leading end of the second link  23  is pivoted on the lower part of the first link  17  by way of a shaft  24  (first coupling shaft). The other end of the second link  23  is pivoted on the upper part of a long coupling rod  27  (transmission member) by way of a shaft  28 . The bracket  20  has a link support portion  51  with a link support surface  52 . The second link  23  has a bracket attachment  53 , a first extension  54  and a second extension  55 . The second link  23  also has a bent portion  56 . 
         [0023]    The first link  17 , the arm  18  and the second link  23  of the upper link mechanism  15  are preliminarily assembled in, preferably, the bracket  20 . As a result, the bracket provided with the link mechanism can be easily assembled in the backrest frame  16  as a unit module. The bracket provided with the link mechanism makes it easy to manage storage parts, and to replace parts in maintenance operations. 
         [0024]    As shown in  FIGS. 2 and 6 , one end of an upper spring  29  is coupled to the lower part of the first link  17 , and the other end of the upper spring  29  is coupled to the side frame  40 . The first link  17  is usually held at a lower waiting position in  FIG. 7  by an elastic force of the spring  29 , and hence the headrest  3  is held at an ordinary position. When the first link  17  moves up to a position indicated by solid line in  FIG. 8 , the upper movable member  10  moves forward, and the headrest  3  is forced out forward. 
         [0025]    Between the side frames  40 ,  40 , a lower movable member  30 , which may be a back-and-forth movable body or a sensing member, stretching laterally is disposed. The lower movable member  30  is pushed by a vehicle seat occupant and moved backward when the vehicle seat relatively moves forward of the occupant due to a rear end collision. Both sides of the lower movable member  30  are coupled to the ends of the lower link  31  (link member) of the lower link mechanism  32  by way of shafts  38  (coupling shafts). The lower movable member  30  comprises a plate-shaped portion  30   e  that connects to the shaft  38  via a coupling plate member  30   a  (also called a coupling member or end extension) through a first extension  30   a   1 , second extension  30   a   2 , and third extension  30   a   3 . The lower movable member  30  also comprises a shaft member  30   g . The other end of the lower link  31  is coupled to the lower part of the coupling rod  27  (transmission member) by way of a shaft  37 . The lower link  31  is preferably a bell crank. The center of the lower link  31  is pivoted on a lower bracket  35  (bracket member) fixed to the side frame  40  by way of a shaft  36  (link support shaft). 
         [0026]    As shown in  FIG. 2 , one end of the lower spring  39  is coupled to the lower movable member  30 , and the other end of the lower spring  39  is coupled to the side frame  40 . The lower movable member  30  is held at a forward ordinary position by the elastic force of the spring  39 , and when a rear end collision occurs, it is pushed by the vehicle seat occupant and moved backward by resisting the elastic force of the spring  39 . 
         [0027]    In  FIGS. 3 and 5 , the backward movement of the lower movable member  30  causes the lower link  31  to rotate counterclockwise about the shaft  36 , and causes the coupling rod  27  to be pulled downward. As a result, the second link  23  rotates counterclockwise about the shaft  25 , and moves the first link  17  upward by resisting the elastic force of the upper spring  29 . At this time, the distance between the shaft  25  and shaft  28  is shorter than the distance between the shaft  25  and shaft  24 . Thus, the second link  23  amplifies the moving amount of the coupling rod  27  (lower movable member  30 ) to transmit the movement to the first link  17 , the upper part of the first link  17  is guided by the arm  18  and moved substantially forward as shown in  FIG. 8 , and thereby the headrest  3  is moved forward by way of the upper movable member  10  so that a cervical spine of the vehicle seat occupant is protected in the event of a rear end collision. 
         [0028]    Thus, the upper link mechanism  15  of this embodiment of the invention has a function of moving the headrest  3  largely forward with a small moving amount of the lower movable member  30 . The lower movable member  30  comprises backward protrusions  30   f . The backward protrusions  30   f  may comprise a first backward protrusion  30   b  (upper backward protrusion) and a second backward protrusion  30   c  (lower backward protrusion). These each may comprise a first bent portion  30   d   1  and a second bent portion  30   d   2 . 
         [0029]    The side frame  40  of the backrest frame  16  is formed of a metal plate having a specified width in the front-to-back direction, and the upper link mechanism  15 , coupling rod  27 , and lower link  31  are disposed adjacent to the side frame  40 . In addition, the members of the upper link mechanism  15  and the lower link  31  are formed of plates substantially parallel to the side frame  40 , and are supported by the shaft in the lateral direction. The upper movable member  10  substantially overlaps with the upper frame  41  of the backrest frame  16 . Therefore, the mechanism for transmitting the movement of the lower movable member  30  to the headrest  3  does not substantially interfere with the cushion  5  of the backrest  2 A. Hence, the transmission mechanism is operated smoothly, and decline of performance of the cushion  5  is prevented. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 TABLE OF REFERENCE CHARACTERS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                  1 
                 vehicle seat 
               
               
                   
                  2A 
                 backrest 
               
               
                   
                  2B 
                 seat bottom 
               
               
                   
                  3 
                 headrest 
               
               
                   
                  4 
                 head support 
               
               
                   
                  5 
                 cushion 
               
               
                   
                  6 
                 pillars 
               
               
                   
                 10 
                 upper movable member; headrest support member 
               
               
                   
                 11 
                 pillar supports 
               
               
                   
                 12a 
                 outward extension 
               
               
                   
                 12b 
                 forward extension 
               
               
                   
                 13 
                 intersection 
               
               
                   
                 14 
                 protrusion 
               
               
                   
                 14a 
                 anteroposterior extension; forward bent portion 
               
               
                   
                 15 
                 upper link mechanism 
               
               
                   
                 16 
                 backrest frame 
               
               
                   
                 17 
                 long first link; downward extension 
               
               
                   
                 18 
                 arm; second link member 
               
               
                   
                 19 
                 shaft; second coupling shaft 
               
               
                   
                 20 
                 L-shaped bracket; bracket; bracket member 
               
               
                   
                 21 
                 shaft; second link support shaft 
               
               
                   
                 23 
                 second link; first link member 
               
               
                   
                 24 
                 shaft; first coupling shaft 
               
               
                   
                 25 
                 shaft; first link support shaft 
               
               
                   
                 27 
                 long coupling rod; transmission member 
               
               
                   
                 28 
                 shaft 
               
               
                   
                 29 
                 upper spring 
               
               
                   
                 30 
                 lower movable member; back-and-forth movable body; 
               
               
                   
                   
                 sensing member 
               
               
                   
                 30a 
                 coupling plate member; coupling member; end extension 
               
               
                   
                 30a1 
                 first extension 
               
               
                   
                 30a2 
                 second extension 
               
               
                   
                 30a3 
                 third extension 
               
               
                   
                 30b 
                 first backward protrusion; upper backward protrusion 
               
               
                   
                 30c 
                 second backward protrusion; lower backward protrusion 
               
               
                   
                 30d1 
                 first bent portion 
               
               
                   
                 30d2 
                 second bent portion 
               
               
                   
                 30e 
                 plate shaped portion 
               
               
                   
                 30f 
                 backward protrusion 
               
               
                   
                 30g 
                 shaft member 
               
               
                   
                 31 
                 lower link; bell crank; link member 
               
               
                   
                 32 
                 lower link mechanism 
               
               
                   
                 35 
                 lower bracket; bracket member 
               
               
                   
                 36 
                 shaft; link support shaft 
               
               
                   
                 37 
                 shaft 
               
               
                   
                 38 
                 shaft; coupling shaft 
               
               
                   
                 39 
                 spring 
               
               
                   
                 40 
                 side frame 
               
               
                   
                 40a 
                 inward extension 
               
               
                   
                 41 
                 upper frame 
               
               
                   
                 42 
                 lower frame 
               
               
                   
                 50 
                 outwardly recessed portion 
               
               
                   
                 51 
                 link support portion 
               
               
                   
                 52 
                 link support surface 
               
               
                   
                 53 
                 bracket attachment 
               
               
                   
                 54 
                 first extension 
               
               
                   
                 55 
                 second extension 
               
               
                   
                 56 
                 bent portion