Patent Publication Number: US-8113575-B2

Title: Vehicle seat

Description:
TECHNICAL FIELD 
     The present invention provides a vehicle seat having a pretensioner device that satisfactorily binds a seated passenger when a vehicle collides. 
     BACKGROUND ART 
     A configuration in which a seat is moved backward by transmitting adversive movement caused by a mutual reaction force between a cylinder and a piston of a pretensioner device through a wire cable has been known (Patent Document 1).
     [Patent Document 1] JP 2008-213546A   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The above publicly known example has a configuration in which a pretensioner device is caused to activate to move a seat backward by transmitting adversive movement caused by a mutual reaction force between a cylinder and a piston of the pretensioner device through a wire cable and thus, while the configuration of the pretensioner device is made simpler, there is a problem that it is necessary to secure a space to allow the seat to move backward. 
     Therefore, there is a problem that a space for feet of a passenger seated in a rear seat is narrow, causing a sense of oppression for the passenger seated in the rear seat. 
     The present application improves a sense of seating in the rear seat of vehicle seats provided with a binding device while maintaining a binding effect of a passenger in a front seat unchanged by devising the seat and the movement configuration of the seat. 
     Means for Solving Problems 
     The present invention provides a vehicle seat including: a backrest seat  2  and a seat  3 , wherein a seat frame  51  of the seat  3  is mounted freely movably back and forth with respect to a fixing frame  46  mounted on one of a body and a slide rail  5 , the seat frame  51  is configured to move backward by a pretensioner device  10  activated by an impact received by the body by leaving the backrest seat  2 , a front portion of a spring material  71  supporting a cushion material  62  of the seat  3  is mounted on the front portion of the seat frame  51 , a rear-side portion of the spring material  71  is mounted on a rear-side spring mounting member  72  in a lateral direction whose position is fixed below the backrest seat  2 , and the cushion material  62  of the seat  3  is configured so that even if the seat  3  moves backward, a rear position of the cushion material  62  does not move. 
     The present invention also provides a vehicle seat including: a backrest seat  2  and a seat  3 , wherein a seat frame  51  of the seat  3  is mounted freely movably back and forth with respect to a fixing frame  46  mounted on one of a body and a slide rail  5 , the seat frame  51  is configured to move backward by a pretensioner device  10  activated by an impact received by the body by leaving the backrest seat  2 , the seat frame  51  is constituted by a front side of a pair of left and right lateral members  55  being coupled by a coupling member  70 , a rear-side spring mounting member  72  in a lateral direction is provided in a predetermined portion of the fixing frame  46  on a rear side from the coupling member  70  spaced by a predetermined distance, a plurality of spring materials  71  in a back-and-forth direction is arranged side by side in the lateral direction between the rear-side spring mounting member  72  and the coupling member  70 , and a cushion material  62  is provided on the spring materials  71 . 
     Effect of the Invention 
     According to the present invention, a front portion of the seat  3  is moved backward so that improvement of the binding effect by the backward movement of the seat  3  and improvement of a sense of seating of a passenger seated in the rear seat can be made compatible. 
     According to the present invention, a rear portion of a spring material  71  is mounted on a rear-side spring mounting member  72  on a rear side from a coupling member  70  spaced by a predetermined distance and therefore, while the front portion of a cushion material  62  of the seat  3  moves backward, a rear-side portion of the cushion material  62  does not move with respect to a backrest seat  2  and improvement of the binding effect by the backward movement of the seat  3  and improvement of a sense of seating of a passenger seated in the rear seat can be made compatible. 
     According to the present invention, a seat frame  51  constituted by a front side of left and right lateral members  55  being coupled by the coupling member  70  is moved backward and therefore, when compared with movement of the cushion material  62  only, the seat frame  51  and the cushion material  62  are integrally moved backward and while the overall amount of movement of the seat  3  is made smaller for a passenger seated in the rear seat, a surrounding space of a passenger in the rear seat is widened and particularly, a space for feet of a passenger in the rear seat can be made wider so that the binding effect of a passenger in the front seat can be improved while improving a sense of seating of a passenger seated in the rear seat. 
     According to the present invention, the binding effect of a seated passenger can be improved by making movement of the seat frame  51  smoother by a mounting hole  56  and a mounting member  57 . 
     According to the present invention, a pretensioner device  10  can be configured in such a way that the seat  3  is moved backward by transmitting movement caused by a reaction force of a piston  12  of one cylinder  11  and a cylinder case  11 A through a wire cable  13  so that an installation space of the pretensioner device  10  can be made smaller and an intrusion space of the seat  3  into the surrounding space of a passenger in the rear seat can be made “zero” or as small as possible. 
     According to the present invention, the seat  3  can be moved backward even though a towing direction of the wire cable  13  by the piston  12  and the cylinder case  11 A is a lateral direction and therefore, the pretensioner device  10  can be provided by making effective use of a space below the seat  3 , which makes the configuration reasonable. 
     According to the present invention, the cylinder case  11 A of the cylinder  11  is supported by the wire cable  13 , which eliminates the need to specifically prepare a dedicated mounting member, makes the mounting work of the cylinder  11  easier, and reduces the weight and cost of the cylinder  11 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle seat and seat belt, a tongue plate, and an inner lap anchor. 
         FIG. 2  is a sectional view of an example of a pretensioner device. 
         FIG. 3  is a schematic view showing a movement state of a cylinder and piston of the pretensioner device and the movement state of a cable. 
         FIG. 4  is a schematic view showing an example of arrangement of the pretensioner device and a cable guide. 
         FIG. 5  is a perspective view of a seat frame. 
         FIG. 6  is a side view of the seat frame in a backward movement state. 
         FIG. 7  is a perspective view of the pretensioner device and a seat frame in another embodiment. 
         FIG. 8  is a perspective view of the seat frame from which the pretensioner device and a spring material are omitted. 
         FIG. 9  is a perspective view of the seat frame from which the pretensioner device and the spring material are omitted. 
         FIG. 10  is a side view of the seat frame in the backward movement state. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be described with reference to drawings. Reference numeral  1  is a vehicle seat, reference numeral  2  is a backrest seat of the vehicle seat  1 , reference numeral  3  is a seat, reference numeral  4  is a headrest provided in an upper portion of the backrest seat  2 , and reference numeral  5  is a slide rail that moves the vehicle seat  1  with respect to the body. 
     The vehicle seat  1  is provided with the pretensioner device  10  of a moving device K that moves the seat  3  backward while leaving the backrest seat  2  intact by generating a large quantity of gas through ignition of a gas forming agent. 
     The pretensioner device  10  is provided with a piston  12  inside a cylinder case  11 A of a cylinder  11 . An end of one of a pair of a one side cable  13 A and another side cable  13 B of the wire cable  13  is connected to the side of the piston  12  inside the cylinder case  11 A. The end of the other of the one side cable  13 A and the other side cable  13 B is connected to a cylinder-side wire locking unit  17  of the cylinder case  11 A of the cylinder  11 . 
     The other end of each of the one side cable  13 A and the other side cable  13 B is connected to any locking unit T of the vehicle seat  1 . 
     The cylinder  11  is freely movably mounted on a predetermined fixing portion of the vehicle seat  1  so that the cylinder case  11 A and the piston  12  each move in directions opposite to each other due to a reaction force. 
     The cylinder case  11 A is provided with a gas generator  16  that supplies a large quantity of gas to move the piston  12 . Any configuration may be adopted for the gas generator  16  and the gas generator  16  is provided outside the cylinder case  11 A. 
     Though not illustrated, the gas generator  16  contains a gas forming agent to generate a gas therein and is configured to move the piston  12  by gas pressure of a high pressure gas generated from the gas forming agent. 
     The gas generator  16  is provided on an outside surface of an end of the cylinder case  11 A provided on the opposite side of the cylinder-side wire locking unit  17 . The gas generator  16  is made to face a gas jetting chamber  20  inside the cylinder case  11 A. The piston  12  is made to face the gas jetting chamber  20  and a piston rod  21  is mounted on the piston  12 . The wire cable  13  is connected to the piston rod  21 . Thus, the wire cable  13  is connected to the piston  12  via the piston rod  21 . 
     The piston rod  21  is freely movably mounted on the cylinder  11 . In the embodiment, the piston rod  21  is freely movably inserted into an internal cylinder member (seal extension unit)  22  of the cylinder  11 . The base of the internal cylinder member  22  is mounted on the cylinder  11  and the tip of the internal cylinder member  22  is made to open inside the gas jetting chamber  20 . While the internal cylinder member  22  is formed integrally with a micro gas generator housing  23  and the tip of the internal cylinder member  22  is positioned in a predetermined location inside the cylinder  11  in  FIGS. 2 and 3 , the tip may be positioned anywhere inside the cylinder  11  and any configuration may be adopted for the internal cylinder member  22 , which may also be formed separately from the micro gas generator housing  23 . 
     If an O ring  38  is provided on an inner circumference at the tip of the internal cylinder member  22  ( FIG. 3 ), the O ring  38  is brought into close contact with the outside surface of the piston rod  21  so that adhesiveness between the moving piston rod  21  and the O ring  38  of the internal cylinder member  22  is improved, preventing leakage of a gas generated by the gas generator  16  from the cylinder case  11 A as much as possible. 
     The piston rod  21  connected to the one side cable  13 A is closely inserted into the internal cylinder member  22  and the piston  12  is mounted on the piston rod  21  projecting from the internal cylinder member  22 . The piston  12  is freely movably provided inside the cylinder case  11 A. A rod mounting portion  24  is provided on the piston  12  and a screw portion formed on an end of the piston rod  21  is screwed into the rod mounting portion  24  to mount the piston  12  on the piston rod  21 . 
     A major diameter portion  26  slidingly in contact with the inner circumference of the cylinder case  11 A is formed on an outer circumference of the fitting cylinder member  21 . The major diameter portion  26  blocks the side of the cylinder-side wire locking unit  17  of the cylinder case  11 A. 
     A coupler  32  is connected to the gas generator  16 . A harness  33  connected to the coupler  32  is connected to an impact detection device  34  provided in a body desired position. When the impact detection device  34  detects an impact, the gas generator  16  generates a large quantity of gas, fills the gas jetting chamber  20  inside the cylinder case  11 A with the large quantity of gas, and tows the wire cable  13  by instantaneously moving the piston  12  with gas pressure at this time to activate the pretensioner device  10 . 
     An O ring  35  is provided on the major diameter portion  26  of the piston  12 . An inclined surface  37  with a gradually decreasing diameter is formed on the major diameter portion  26  of the piston  12  from the major diameter portion  26  toward the cylinder-side wire locking unit  17  to contain a rigid sphere  36  for a stopper to stop return movement of the piston  12  in a space between the inclined surface  37  and an inner circumferential surface of the cylinder case  11 A. 
     Any concrete configuration can be adopted for the pretensioner device  10 . For example, a pair of left and right fixing frames  46  are each mounted on left and right upper rails  35 A of the slide rails  5  provided in a body and a seat frame  51  of the seat  3  is mounted on the left and right fixing frames  46  backward movably within a predetermined range. 
     Thus, the fixing frame  46  is set as a locking unit T and the bases of the one side cable  13 A and the other side cable  13 B of the pair of left and right wire cables  13  are each connected to the fixing frames  46 . 
     One of tips of the one side cable  13 A and the other side cable  13 B of the wire cables  13  is connected to the piston rod  21  of the piston  12  provided inside the cylinder case  11 A of the cylinder  11  of the pretensioner device  10  and the other tip of the one side cable  13 A and the other side cable  13 B is connected to an end of the cylinder case  11 A. 
     The pretensioner device  10  moves the seat  3  backward by towing each of the one side cable  13 A and the other side cable  13 B of the wire cables  13  by one cylinder  11  constituted of one cylinder case  11 A and one piston  12  and also towing the seat frame  51  substantially simultaneously. 
     In this case, if the bases of an anchor plates  41  and an inner lap anchor  42  of the left and right of a seat belt  40  are mounted on the left and right fixing frames  46 , the seat belt  40  can be pretensioned as the seat  3  moves backward, improving the binding effect. 
     The cylinder case  11 A of the cylinder  11  of the pretensioner device  10  is positioned so that the towing direction of the wire cable  13  and a shaft of the cylinder case  11 A are substantially in parallel below the seat frame  51  and configured to be freely movably installed in the shaft direction of the cylinder case  11 A, and thus, the pretensioner device  10  moves the seat  3  backward by the one cylinder  11 . 
     In intermediate positions of the one side cable  13 A and the other side cable  13 B of the wire cables  13  each locked to the cylinder case  11 A or the piston  12  between the left and right fixing frames  46  (locking unit T) and the cylinder case  11 A, cable guides  61  that changes the towing direction of the one side cable  13 A and the other side cable  13 B towed in the lateral direction by the piston  12  and the cylinder case  11 A to a back-and-forth direction are provided so that the seat  3  can be moved backward ( FIGS. 4 ,  7 ,  8 , and  9 ). 
     The cylinder case  11 A of the pretensioner device  10  is formed to a predetermined length and arranged with a movement space to be able to tow the wire cable  13  between the left and right cable guides  61  as much as necessary. 
     The diameter and length of the cylinder case  11 A and the amount of towing of the wire cable  13  are considered and set so that the amount of movement of the cylinder case  11 A falls between the left and right cable guides  61 . That is, an interval greater than the amount of movement of the cylinder case  11 A may be provided between the cable guide  61  provided in the movement direction of the cylinder case  11 A and the end of the cylinder case  11 A. 
     The cylinder case  11 A is provided in a suspended state by the one side cable  13 A and the other side cable  13 B between the left and right cable guides  61 . Thus, the cylinder case  11 A is supported by the wire cable  13 . 
     Any concrete movement configuration may be adopted for the seat  3 . For example, in the embodiment in  FIGS. 1 and 5 , bar-shaped mounting members  57  are provided in forward/backward portions on both sides of a pair of left and right lateral members  55  of the seat frame  51  and the mounting members  57  are each engaged in mounting holes  56  provided in the fixing frames  46 . 
     In a second embodiment shown in  FIGS. 7 to 9 , the mounting holes  56  are formed in rear-side portions of the pair of left and right lateral members  55  of the seat frame  51 , the bar-shaped mounting members  57  provided in the fixing frames  46  are each engaged in the mounting holes  56 , and front portions of the seat frame  51  are mounted, in contrast to the first embodiment, as shown in  FIGS. 6 to 9 , with an upper portion of an arm  58  being freely rotatably mounted by an axis  59  and a lower portion of the arm  58  being freely rotatably mounted on the fixing frames  46  by an axis  60  without using the mounting holes  56  and the mounting members  57 . Thus, when the seat  3  retreats after a collision, the seat  3  can retreat while raising a front end thereof so that the binding effect of the seated passenger by the seat belt  40  can suitably be further improved ( FIGS. 7 to 9 ). 
     The seat frame  51  of the seat  3  is constituted by the front side of the pair of left and right lateral members  55  being coupled by the coupling member  70 . A front portion of a spring material  71  in the back-and-forth direction is mounted on the coupling member  70 . A plurality of spring materials  71  is placed side by side in the lateral direction. A rear portion of the spring material  71  is mounted on the rear-side spring mounting member  72 . The rear-side spring mounting member  72  is formed prolonged in the lateral direction. Left and right ends of the rear-side spring mounting member  72  are fixed to the left and right fixing frames  46 . 
     The cushion material  62  is placed on the rear-side spring mounting member  72  and the outer circumference of the cushion material  62  is encircled with a skin member  63 . That is, the front portion of the spring material  71  is mounted on the front portion of the seat frame  51  and the rear-side portion of the spring material  71  is mounted on the rear-side spring mounting member  72  whose position is fixed below the backrest seat  2 , and the seat  3  is configured so that the front portion of the seat  3  is moved backward by the pretensioner device  10 . 
     The rear-side spring mounting member  72  is provided on the rear side from the coupling member  70  spaced by a predetermined distance by associating with the back-and-forth length of the cushion material  62  and the cushion material  62  is provided on the spring material  71  between the rear-side spring mounting member  72  and the coupling member  70 . 
     If the rear-side spring mounting member  72  is positioned below the backrest seat  2 , the back-and-forth length of the cushion material  62  can suitably be prolonged. If, regarding the rear-side spring mounting member  72  and the left and right lateral members  55 , the rear end of the lateral members  55  is positioned toward the front from the rear-side spring mounting member  72  by the distance of backward movement of the seat frame  51 , interference between the seat frame  51  and the rear-side spring mounting member  72  can suitably be prevented when the seat  3  moves backward. 
     If the back-and-forth length of the lateral member  55  is prolonged, rigidity of the seat frame  51  can be improved and movement of the seat frame  51  is made smoother. If at least the height of the rear portion of the length of the seat frame  55  by which the seat  3  moves backward is made lower than the rear-side spring mounting member  72 , interference between the seat frame  51  and the rear-side spring mounting member  72  when the seat  3  moves backward can suitably be prevented while improving rigidity of the seat frame  51  by prolonging the back-and-forth length of the lateral members  55  as much as possible. 
     If the front portion of the spring material  71  is provided in such a way that the front portion of the spring material  71  is higher than the rear-side portion thereof in advance, the spring material  71  can easily be deformed when the seat  3  moves backward so that backward movement of the seat  3  can be made more swift and smoother. 
     The cushion material  62  is configured so that rear position thereof does not move even if the rear-side portion of the spring material  71  is mounted on the rear-side spring mounting member  72 , the rear portion of the spring material  71  is not allowed to move toward the rear beyond the rear-side spring mounting member  72 , and the seat  3  moves backward. 
     In this case, it is only necessary to make the rear position of the cushion material  62  immovable even if the seat  3  moves backward and any configuration may be adopted to move the cushion material  62  backward integrally with the seat frame  51 . For example, the skin member  63  may be tied up to the coupling member  70  of the seat frame  51  so that the front portion of the cushion material  62  moves backward integrally with the coupling member  70  due to the skin member  63 . 
     Though not illustrated, if a height adjustment mechanism to adjust the height of the vehicle seat  1  by moving the vehicle seat  1  vertically with respect to the body, the fixing frame  46  moves vertically with respect to the upper rail  35 A. Thus, the anchor plates  41  and the inner lap anchor  42  on the left and right sides are mounted on the upper rails  35 A, instead of the fixing frames  46 , to support the load on the seat belt  40  by the slide rails  5  and also the cable guides  61  and a reinforcing frame  90  are mounted on the side of the upper rails  35 A. 
     Reference numeral  47  is a belt retractor, reference numeral  65  is a tongue plate provided in an intermediate portion of the seat belt  40 , and reference numeral  66  is an inner buckle. When the tongue plate  65  is engaged in the inner buckle  66 , the seat belt  40  becomes a shoulder belt  67  from a portion near the shoulder of the seated passenger of one end of the belt retractor  47  to the tongue plate  65  and a lap belt  68  from the tongue plate  65  to the anchor plate  41 . Reference numeral  69  is a through anchor. 
     The belt retractor  47  is a publicly known configuration and needs to contain a mechanism that normally allows the seat belt  40  to be withdrawn, but when an impact is felt, locks withdrawal of the seat belt  40 . 
     The tongue plate  65  is also a publicly known configuration and is configured to be freely movable with respect to the seat belt  40 , but to be immovable with respect to the seat belt  40  when the seat belt  40  is normally withdrawn. 
     Operation of the Embodiments 
     When an impact is received after a collision from the front during traveling while being seated in the vehicle seat  1 , an inertial force acts to move the seated passenger forward with respect to the vehicle seat  1 , but the seated passenger is bound to the vehicle seat  1  due to the seat belt  40 . 
     However, while the seated passenger is bound by the seat belt  40 , there is a limit to improvement of the binding effect by the seat belt  40  during collision. Thus, while attempts have been made to bind the seated passenger by actively pretensioning the seat belt using a pretensioner during collision in recent years, only one side of the left and right of the seat belt is towed according to the conventional configuration to pretension the seat belt and therefore, there is a limit to improvement of the binding effect by moving forward the startup of a binding force still further. 
     Thus, the moving device K that moves the seat  3  backward is provided in the vehicle seat  1 , the vehicle seat  1  or the fixing frame  46  provided in the body is set as the locking unit T, and only the seat  3  is instantaneously moved backward with respect to the fixing framer  46  (the slide rail  5 ) by the pretensioner device  10  when a collision is detected independent of the seat belt  40  while the backrest seat  2  of the vehicle seat  1  is left intact and therefore, the startup of a binding force is moved forward by moving the seat  3  backward and the binding effect of the seated passenger to the vehicle seat  1  is improved by reducing the amount of movement of the seated passenger. 
     That is, the binding effect of the seated passenger to the vehicle seat  1  is improved by the seated passenger being supported by the seating surface of the seat  3  moved backward. In this case, only the seat  3  of the vehicle seat  1  is moved backward and the backrest seat  2  is not moved backward and therefore, the volume occupied by the vehicle seat  1  of the rear space can be minimized. 
     Further, the front portion of the spring material  71  supporting the cushion material  62  is mounted on the front portion of the seat frame  51  and the rear-side portion of the spring material  71  is mounted on the rear-side spring mounting member  72  whose position is fixed and which is below the backrest seat  2  and therefore, the front portion of the seat  3  is moved backward by the pretensioner device  10 , but the rear portion thereof is not moved backward and remains below the backrest seat  2 , further minimizing the volume occupied by the vehicle seat  1  of the rear space and making improvement of the binding effect by the backward movement of the seat  3  and improvement of a sense of seating of a passenger in the rear seat compatible. 
     More specifically, the seat frame  51  of the seat  3  is constituted by the front side of the pair of left and right lateral members  55  being coupled by the coupling member  70 , the front portion of the spring material  71  in the back-and-forth direction is mounted on the coupling member  70 , the rear portion of the spring material  71  is mounted on the rear-side spring mounting member  72 , and the left and right ends of the rear-side spring mounting member  72  are each fixed to the fixing frames  46  and therefore, only the rear portion of the pair of left and right lateral members  55  of the seat frame  51  of the seat  3  is moved backward and the rear-side spring mounting member  72  remains below the backrest seat  2  without being moved backward. 
     Therefore, the rear portion of the spring material  71  does not move toward the rear beyond the rear-side spring mounting member  72  so that the volume occupied by the vehicle seat  1  of the rear space can be minimized. 
     Since the rear portion of the spring material  71  does not move toward the rear beyond the rear-side spring mounting member  72 , the rear position of the cushion material  62  is hardly moved even if the seat  3  is moved backward. 
     On the other hand, the seat frame  51  constituted by the front side of the left and right lateral members  55  being coupled by the coupling member  70  moves backward and therefore, while the rear position of the cushion material  62  is hardly moved, the front portion of the cushion material  62  is moved backward integrally with the seat frame  51 . 
     Therefore, the overall amount of movement of the seat  3  can be made smaller for a passenger seated in the rear seat, a surrounding space for a passenger seated in the rear seat can be made wider while improving the binding effect by sufficient backward movement of the seat  3 , and particularly a space for feet of a passenger seated in the rear seat can be made wider so that improvement of a sense of seating of a passenger seated in the rear seat and improvement of the binding effect of a passenger seated in the front seat can be made compatible. 
     The rear-side spring mounting member  72  is provided on the rear side from the coupling member  70  spaced by a predetermined distance by associating with the back-and-forth length of the cushion material  62 , the cushion material  62  is provided on the spring material  71  between the rear-side spring mounting member  72  and the coupling member  70 , the rear-side spring mounting member  72  is positioned below the backrest seat  2  and therefore, the back-and-forth length of the cushion material  62  can be made longer, which can suitably improve a sense of seating by improved cushioning properties. 
     If the back-and-forth length of the cushion material  62  is made longer, rigidity of the seat frame  51  is improved and therefore, regarding the rear-side spring mounting member  72  and the left and right lateral members  55 , if the rear end of the lateral members  55  is arranged toward the front from the rear-side spring mounting member  72  by the distance of backward movement of the seat frame  51 , interference between the seat frame  51  and the rear-side spring mounting member  72  can suitably be prevented further when the seat  3  moves backward. 
     If at least the height of the rear portion of the length of the lateral members  55  by which the seat  3  moves backward is made lower than the rear-side spring mounting member  72 , interference between the seat frame  51  and the rear-side spring mounting member  72  when the seat  3  moves backward can be prevented while improving rigidity of the seat frame  51  by prolonging the back-and-forth length of the lateral members  55  as much as possible. 
     The bar-shaped mounting members  57  are provided in the forward/backward portions on both sides of the pair of left and right lateral members  55  of the seat frame  51  of the seat  3  and the mounting members  57  are relatively freely movably inserted into the mounting holes  56  provided in the fixing frames  46  and prolonged back and forth and therefore, the seat  3  moves backward with respect to the fixing frame  46  by the seat frame  51  being guided by the mounting members  57  and the mounting holes  56 . 
     In this case, like the second embodiment in  FIGS. 7 to 9 , the front portion of the seat frame  51  is vertically freely movably mounted to the arm  58  and therefore, when the seat  3  retreats after a collision, the seat  3  can be made to retreat while raising the front end thereof so that the binding effect of the seated passenger by the seat belt  40  can suitably be further improved. 
     The fixing frame  46  fixed to the slide rail  5  in a fixed state with respect to the body is set as the locking unit T, each end of the one side cable  13 A and the other side cable  13 B of the pair of left and right wire cables  13  is locked to the fixing frame  46 , one of tips of the one side cable  13 A and the other side cable  13 B of the wire cables  13  is connected to the piston rod  21  of the piston  12  provided inside the cylinder case  11 A of the pretensioner device  10  and the other tip of the one side cable  13 A and the other side cable  13 B is connected to the side of the cylinder case  11 A and therefore, when an impact is detected by the impact detection device  34  provided in a body desired position, the pretensioner device  10  moves the seat  3  backward by towing the wire cable  13  and towing the seat frame  51 . 
     The pretensioner device  10  is positioned so that the towing direction of the wire cable  13  and the shaft of the cylinder case  11 A are in parallel with respect to the vehicle seat  1  and the cylinder case  11 A is arranged freely movably only in the shaft direction of the cylinder case  11 A and therefore, a reaction force of the piston  12  that is instantaneously moved by a large quantity of gas by the gas generator  16  acts on the freely movable cylinder case  11 A so that the piston  12  and the cylinder case  11 A each move in directions opposite to each other. 
     Consequently, the one side cable  13 A locked to the wire cable mounted on the piston rod  21  of the piston  12  and the other side cable  13 B connected to the cylinder case  11 A become a single-state cable without looseness so that the one side cable  13 A and the other side cable  13 B are towed substantially simultaneously by substantially the same amount to be able to move the seat frame  51  backward and can be provided at low prices by reducing the number of components of the mechanism to bind a seated passenger. 
     The cylinder case  11 A of the pretensioner device  10  is mounted on a front underside of the seat frame  51 , the cable guides  61  are provided in left and right intermediate portions of the seat frame  51 , and the one side cable  13 A and the other side cable  13 B are each turned to the direction of the rear portion of the fixing frame  46  at each of the cable guides  61  before being locked to the rear portion of the fixing frame  46  (locking unit T) and therefore, contact with other components of the vehicle seat  1  when moving in a mutually relatively reducing direction of the one side cable  13 A and the other side cable  13 B can be prevented satisfactorily and reliably, the amount of movement of the seated passenger is reduced by backward movement of the seat  3 , and the binding effect of the seated passenger to the vehicle seat  1  is improved. 
     The pretensioner device  10  is configured so that one cylinder  11  is arranged below the front underside of the seat frame  51  of the seat  3  and the shaft direction of the cylinder  11  becomes the lateral direction and therefore, a mechanism to bind a seated passenger can be installed without sacrificing foot insertability of the passenger when seated in the rear vehicle seat  1  of the vehicle seat  1  and in addition, the pretensioner device  10  can be activated satisfactorily and reliably. 
     The cylinder  11  of the pretensioner device  10  is configured to be provided in a suspended state by the pair of the one side cable  13 A and the other side cable  13 B of the wire cable  13  between the left and right cable guides  61  for belt so as to support the cylinder  11  by the wire cable  13  and therefore, the cylinder case  11 A is supported by the wire cable  13 , which eliminates the need to specifically prepare a dedicated mounting member and makes the mounting work of the cylinder  11  easier. 
     The cylinder  11  of the pretensioner device  10  is arranged with a movement space allowing to tow the wire cable  13  as much as necessary and therefore, even if the cylinder case  11 A moves due to action of the gas generator  16 , the cylinder case  11 A is prevented from coming into contact with the cable guide  61  to make activation thereof more reliable. 
     That is, an interval greater than the amount of movement of the cylinder case  11 A itself is provided between the cable guide  61  provided in the movement direction of the cylinder case  11 A and the end of the cylinder case  11 A and therefore, even if the cylinder case  11 A itself moves, the cylinder case  11 A is prevented from coming into contact with the cable guide  61 . 
     Each embodiment described above is illustrated and described individually or mixedly, but these embodiments can be combined in various ways and the configuration, operations, and the like are not limited by such representations and naturally cases of achieving a multiplier effect are present.