Abstract:
One aspect of the present invention can include a vehicle seat, a seat frame having a cushion frame, the cushion frame with a first and second side frame, a bead extending from an outer side of one of the first and second side frame, the bead including a first and second inclined surface connected at a ridge portion, and a notch portion defined in a lower portion of the at least one of the first and second side frame, wherein the notch portion is positioned proximate the bead.

Description:
This application claims priority to Japanese patent application serial number 2008-006802, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a frame structure of a vehicle seat for absorbing an impact generated upon a rear-end collision by bending of a seat frame. 
     2. Description of the Related Art 
     A vehicle seat includes a seat-cushion, a seat-back and a reclining system. The reclining system connects the seat-back to the seat-cushion so as to be capable of moving between an upright position and a reclined position. 
     When the vehicle encounters the rear-end collision, an occupant seated on the vehicle seat is pressed toward the rear of the seat due to the impact thereof. The seat-back is positioned upright at a predetermined angle of inclination with the reclining system. The occupant must be supported by the seat-back. In order to do so, a configuration (frame structure) which causes another frame component to bend to absorb the impact of the rear-end collision is necessary to protect the reclining system. 
     A kind of a frame structure is described in JP-A-2001-178584. This structure includes a reclining system and a bracket. A cushion frame and a back frame are connected via the reclining system. The back frame is mounted on the reclining system via the bracket. The bracket includes a main plate shaped as a flat plate and a flange to be connected to the main plate. The flange has a substantially L-shape (side cross-sectional view). 
     The bracket includes a bead. The bead is a portion that is formed by depressing an outer wall of the bracket inwardly of the bracket in a triangle shape. The bead is formed on the bracket so as to extend across a borderline between the main plate and the flange. 
     The impact of the rear-end collision of the vehicle is absorbed by bending of the bracket (outer wall) starting from the bead. The impact which is transmitted to the reclining system is alleviated by the impact absorption as described above. 
     However, this frame structure does not include configurations to absorb impact other than bending of the bracket (part of the back frame) by plastic deformation. Therefore, sufficient alleviation of the impact of the rear-end collision is not achieved by the frame structure. 
     The vehicle seat is adapted to transmit the impact of the rear-end collision to the cushion frame which is joined to the back frame. Therefore, the impact of the rear-end collision can be sufficiently absorbed by bending the cushion frame. However, since the occupant is seated on the cushion frame, the cushion frame should not be bent in an arbitrary direction. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention can include a vehicle seat, a seat frame having a cushion frame, the cushion frame with a first and second side frame, a bead extending from an outer side of one of the first and second side frame, the bead including a first and second inclined surface connected at a ridge portion, and a notch portion defined in a lower portion of the at least one of the first and second side frame, wherein the notch portion is positioned proximate the bead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a frame of a vehicle seat, 
         FIG. 2  is an upper front view of a cushion frame, 
         FIG. 3  is a perspective view of a part of the cushion frame, 
         FIG. 4  is a side view of a part of the cushion frame, 
         FIG. 5  is a vertical cross-sectional view taken along a line V-V in  FIG. 4 , and 
         FIG. 6  is a lateral cross-sectional view taken along a line VI-VI in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Each of the additional features and teachings disclosed above and below may be utilize separately or in conjunction with other features and teachings to provide a frame structure of a vehicle seat. Representative examples of the present invention, which examples utilize many of these additional features and teachings both separately and in conjunction with one another, will now be described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Moreover, various features of the representative examples and the dependent claims may be combined in ways that are not specifically enumerated in order to provide additional useful embodiments of the present teachings. 
     Hereafter, a description will be given, referring  FIGS. 1 to 6 , of a best mode for carrying out one aspect of the invention. In each figure, a reference letter F will be given to a front side of a vehicle seat, a reference letter B to a back side of a vehicle seat, reference letter I to a inside of a vehicle seat, and a reference letter L to a lateral side of a vehicle seat. In  FIG. 6 , the length of a notched portion is illustrated to be longer than the actual length for the sake of convenience. 
     Referring to  FIG. 1 , a vehicle seat  2  includes a cushion frame  4 F (a frame of a seat-cushion  4 ), a back frame  6 F (a frame of a seat-back  6 ), a bracket  5  and a reclining system  8 . The bracket  5  is mounted on a lower portion of the back frame  6 F. A rear portion of the cushion frame  4 F is joined to the lower portion of the back frame  6 F via the bracket  5 . 
     The reclining system  8  is provided on the bracket  5 . The reclining system  8  is a member for joining the back frame  6 F to the cushion frame  4 F so as to be capable of moving between the upright position and the reclined position. The reclining system  8  is also a member for controlling an angle of inclination θ 1  of the back frame  6 F with respect to the cushion frame  4 F. Upon a rear-end collision of a vehicle, the reclining system  8  is needed to be protected from an impact of the rear-end collision and maintain the seat-back  6  at a predetermined angle of inclination θ 1 . 
     (Cushion Frame) 
     The cushion frame  4 F includes a front frame  12 , a pair of side frames  14 ,  14  and a pipe frame  16  (see  FIG. 1  and  FIG. 2 ). The front frame  12  is a front framework of the cushion frame  4 F. The pair of side frames  14 ,  14  is side frameworks of the cushion frame  4 F. The pipe frame  16  is disposed on the rear portions of the pair of side frames  14 ,  14  so as to be bridged therebetween. The pipe frame  16  is a member for reinforcing the pair of side frames  14 ,  14 . 
     The pair of side frames  14 ,  14  (of a flat-plate shape) face to each other and is arranged on sides of a vehicle seat. A seating portion (S) for an occupant is formed between the pair of side frames  14 ,  14 . The rear portions of the side frames  14 ,  14  are joined to the lower portion of the back frame  6 F via the bracket  5 . 
     Referring to  FIG. 3 , the upper edge of the side frame  14  protrudes sidewardly of the seat from a side surface  14 I (an upper end flange  20  is formed). The lower edge of the side frame  14  protrudes sidewardly of the seat from the side surface  14 I (an lower end flange  22  is formed). 
     A notched portion  30  and a triangle bead  40  are formed respectively on each of the pair of side frames  14 ,  14  as a configuration to bend the same. 
     (Notched Portion) 
     The notched portion  30  is a weakened portion of the side frame  14 . The notched portion  30  is provided at a position on the front side of the side frames  14  (see  FIG. 2 ). Referring to  FIG. 3 , the notched portion  30  is formed by notching part of the lower end flange  22  in the fore-and-aft direction of the seat. Specifically, the notched portion  30  is formed by notching the part of the lower end flange  22  into a substantially rectangular shape. 
     The notched portion  30  of the side frame  14  is thinner and weaker than other arbitrary positions of the side frame  14  (positions formed the lower end flange  22 ). The side frame  14  can be bent at the position where the notched portion  30  is formed relatively easily upon reception of the impact of the rear-end collision. 
     A front end  34  and a rear end  32  of the notched portion  30  are formed by cutting out the side frame  14  from the lower end toward the upper end (see  FIG. 4 ). The rear end  32  of the notched portion  30  is cut out substantially vertically from the lower end toward the upper end of the side frame  14 . The rear end  32  is a portion where a stress of the impact is initially concentrated upon the rear-end collision. Therefore, the rear end  32  is weakest position of the side frame. 
     The front end  34  of the notched portion  30  is obliquely cut out from the lower end toward the upper end of the side frame  14 . The impact of the rear-end collision is transmitted firstly to the rear end  32  of the notched portion  30 , and then reaches the front end  34 . 
     (Bead) 
     The triangle bead  40  is a starting point of the bending of the notched portion  30 . The triangle bead  40  is provided on each of the pair of side frames  14 ,  14 . Specifically, the triangle bead  40  is formed on the front side of the side frame  14  corresponding to the position where the notched portion  30  is formed (see  FIG. 2 ). 
     Referring to  FIG. 5 , the triangle bead  40  is formed by bending part of the side surface  14 I outward (outwardly of the seat). In other words, the triangle bead  40  is a portion of the side surface  14 I bulged outward (protruded portion), and is a portion where the bending of the side frame  14  starts. 
     The triangle bead  40  includes a pair of inclined surfaces  42 ,  44  and a center ridge  46  which partitions the pair of inclined surfaces  42 ,  44  (see  FIG. 3  and  FIG. 4 ). One apex of the triangle bead  40  is formed on a lower portion of the side surface  14 I. Another apex of the triangle bead  40  is formed on the lower end flange  22 . The center ridge  46  is a protruded portion extending substantially vertically in the top-and-bottom direction of the seat so as to connect the one apex and the other apex. 
     The pair of inclined surfaces  42 ,  44  is obliquely formed respectively from the center ridge  46  toward the side surface  14 I. A terminal end of the inclined surface  42  (a bead rear end  40 BE) is arranged on a rear side B of the seat. A terminal end of the inclined surface  44  (a bead front end  40 FE) is arranged on a front side F of the seat. 
     At the time of the rear-end collision of the vehicle, the pair of side frames  14 ,  14  should be bent outward (outwardly of the seat) respectively by the triangle beads  40 . Referring to  FIG. 6 , the pair of the side frames  14 ,  14  should be bent outward along the pair of inclined surfaces  42 ,  44  (at a bent angle θ 2 ). 
     Assumed that the bead rear end  40 BE (the terminal end of the inclined surface  42 ) is formed at the notched portion  30 , such that the bead rear end  40 BE is arranged towards the front side F with respect to the seat in relation to the rear end  32  of the notched portion  30  (see the portion indicated by a broken line in  FIG. 6 ). At the bead rear end  40 BE, the inclined surface  42  and the side surface  14 I are in a state of bent inwardly of the seat at an angle θ 3 . In other words, the bead rear end  40 BE is depressed with respect to the center ridge  46  (a depressed point  40   ex  is formed). In addition, the bead rear end  40 BE (the depressed point  40   ex ) is arranged near the rear end  32  than to the center ridge  46 . Therefore, the impact of the rear-end collision is transmitted first to the depressed point  40   ex  in the course of being transmitted from the rear end  32  to the front end  34 . When the impact of the rear-end collision is transmitted to the depressed point  40   ex,  it serves as the starting point of bending, so that the side frame  14  might be bent. At this time, the side frame  14  has a risk of being bent inwardly at the angle θ 3  by the depressed point  40   ex.    
     Therefore, the bead rear end  40 BE can be arranged on the back side B of the seat with respect to the rear end  32  (see the portion indicated by a solid line in  FIG. 6 ). In other words, by not forming the depressed point  40   ex  in the notched portion  30 , the side frames  14 ,  14  can be bent outwardly at positions where the notched portion  30  is formed. In this configuration, bending of the pair of side frames  14 ,  14  inwardly is prevented or reduced when a stress is applied to the notched portions  30 . Specifically, the pair of side frames  14 ,  14  can be bent outward further reliably (at the bent angle θ 2 ) with the triangle beads  40  (the center ridges  46 ) as the starting point of bending. 
     In addition, the center ridge  46  can be positioned right above the rear end  32  (the weakest portion) of the notched portion  30 . The stress is concentrated to the rear ends  32  of the notched portions  30 . Therefore, the side frames  14 ,  14  are respectively bent smoothly outwardly along the pair of inclined surfaces  42 ,  44  (at the bent angle θ 2 ) from the center ridges  46  (see  FIG. 2 ). 
     In this configuration the impact of the rear-end collision is effectively absorbed by the pair of side frames  14 ,  14  being bent outward (in the desired direction). Therefore, according to this embodiment, the reclining system  8  is protected from the impact of the rear-end collision further reliably. Then, by maintaining the seat-back  6  at the predetermined angle of inclination θ 1  by the reclining system  8 , the occupant during a rear-end collision is supported. 
     Further, in this configuration, the pair of side frames  14 ,  14  is bent outward so as to move the notched portions  30  away from each other. At the time of a rear-end collision, the width of a portion between the pair of side frames  14 ,  14  (the seating portion (S) of the occupant) is increased, so that the occupant is fitted into the widened seating portion (S). Therefore, the occupant is hardly moved out from the vehicle seat  2 , so that the safety of the vehicle seat  2  at the time of a rear-end collision is improved. 
     ALTERNATIVE EMBODIMENTS 
     The frame structure of a vehicle seat of the embodiment is not limited to the previously described embodiments, and therefore it is possible to adopt various other embodiments. 
     (1) As described above, the notched portion  30  can be formed on the lower end flange  22 . As an alternative configuration, the notched portion  30  can be formed on the upper end flange  20 . The center ridge  46  can be arranged right below the upper end flange  20 . In this configuration, the pair of side frames  14 ,  14  can be bent smoothly outwardly with the triangle beads  40 . 
     The notched portions  30  and the triangle bead  40  can be formed both on the lower end flange  22  and the upper end flange  20 . 
     (2) As described above, the center ridge  46  can be arranged right above the rear end  32  of the notched portion  30 . As an alternative configuration, the bead rear end  40 BE can be arranged on the back side B of the seat with respect to the rear end  32  of the notched portion  30 . The center ridge  46  can be arranged on the front side F of the seat of the rear end  32  of the notched portion  30 . 
     (3) The notched portion  30  and the triangle bead  40  can be provided only on one of the pair of side frames  14 ,  14 . 
     (4) The position to form the notched portion  30  is not specifically limited. The notched portion  30  can be formed at a center position or a rear position of the side frame  14  in terms of the fore-and-aft direction of the seat. 
     The notched portions  30  of the pair of side frames  14 ,  14  can be formed at the same positions or different positions shifted in terms of the fore-and-aft direction of the seat. 
     As described above, the upper end flange  20  and the lower end flange  22  can be provided with the side frame  14  (the property of reinforcement of the side frame is enhanced). As an alternative configuration, the side frame  14  can be formed into a simple flat plate shape (a simple configuration).