Abstract:
To maintain rigidity of a seat cushion frame at a seating position, an operating member ( 14 ) is axially supported pivotably by a lower arm ( 3 ) and a position of a wheel capable of pressing a floor is changed in accordance with a pivoting angle of the operating member ( 14 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a seat structure for a vehicle, and particularly to a foldable or collapsible rear seat structure for the vehicle. 
     According to a rear seat for three passengers for a vehicle, as shown in FIG. 4, the rear seat is constructed such that a seat cushion frame  2  which is a constituent part of a seat cushion, is fixed to two pieces of rail devices  1  fixed to a floor of the vehicle and is constructed to include a seat back frame  4  which is a constituent part of a seat back supported by the seat cushion frame  2  via lower arms  3  installed on both sides at a rear portion of the seat cushion frame  2  and on the rear side of one of the rail devices  1 . 
     Hinge devices  5  installed on the front side of the rail devices  1  enable to forwardly fold the seat and lock devices  6  installed at the rail devices  1  and the seat cushion frame  2  operate to fix the seat to the floor. An example of the lock device  6  is disclosed in Japanese Patent Laid-Open Publication No. 137054/1988. 
     Belt anchor points  7  are installed at the rail devices  1  and disperse load applied to seat belts toward the floor. 
     The load applied to the seat belt needs to be dispersed to the floor via the rail devices  1  and accordingly, an interval between the pair of rail devices  1  is restricted, a dimension of the three passenger rear seat in the width direction is considerably extended in side directions from the rail devices  1  and a problem in view of strength exists in this structure. 
     Further, the rail device  1  may be constituted by a lower rail fixed to the floor and an upper rail slidable with respect to the lower rail or may be constituted only by the lower rail. The seat cushion frame  2  and the seat back frame  4  may be coupled via a conventional reclining mechanism. 
     With regard to the extension of the three passenger rear seat in the transverse direction, for example, as disclosed in Japanese Patent Laid-Open Publication No. 282352/1996, lock devices locked to the floor may be installed also on both sides of the rear portion of the seat cushion frame to thereby maintain the rigidity. 
     However, in this case, the number of points of fixing the seat cushion frame to the floor by using the lock devices increases, and the increase in the fixing points may cause warp at the floor, further, considering synchronous locking performance of all the lock crevices, this is not necessarily regarded as preferable means. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is to overcome disadvantage of the above-described conventional structure. 
     In order to resolve the above-described problem, basically, the present invention provides means for arranging pressing members for pressing a floor at both side portions on the rear side of the seat cushion frame. Specifically, the present invention provides a seat structure for a vehicle constituted by installing pressing members which are installed at both side portions on a rear side of a seat cushion frame and pressed with respect to the floor by urging force of urging members. 
     According to the above technical conception, the pressing members are pressed to the floor whereby the rigidity of the rear cushion frame is ensured. At this occasion, the pressing members only press the floor and accordingly, there is no increase in the number of points of fixing the seat cushion frame to the floor by using lock devices. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an example according to the invention; 
     FIG. 2 is a disassembled perspective view of the example according to the invention; 
     FIG. 3 is a front view of the example according to the invention; and 
     FIG. 4 is a perspective view showing a representative frame structure of a three passenger rear seat. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Although preferable embodiments are installed on both sides of the seat cushion frame  2  as shown in FIG. 4 respectively, an example of applying to the right side is illustrated in FIG.  1  and FIG. 2. A symmetrical constitution is arranged on the left side and accordingly, an explanation thereof will be omitted. 
     Further, the same members as those in the conventional structure are attached with the same numerals and an explanation thereof will be omitted. 
     Refer to FIG.  1  and FIG. 2. A lower portion of a lower arm  3  is fixedly attached to a vicinity of an intersection of a side member  10  and a rear member  11  of the seat cushion frame  2 . The lower arm  3  is perforated with a pin hole  12  for coupling an upper arm (not illustrated), and a elongated hole  13  extended obliquely in a upper direction at its front lower portion. 
     The lower arm  3  supports an operating member  14  in a plate-like shape by using a pin  15  pivotably relative to the lower arm  3 . The operating member  14  is provided with a cam hole  16  in a shape of a circular arc, a spring locking piece  17  and a seat back frame contact piece  18 . 
     One end of a spring  29  is engaged with the spring locking piece  17  and other end thereof is fixed to an upper portion of the lower arm  3 , and the operating member  14  is urged in the counterclockwise direction in view of FIG.  1 . 
     A bracket  19  substantially in a box shape is fixedly attached to an end of the rear member  11  of the seat cushion frame  2 . The bracket  19  is provided with separately opposed vertical wall portions  20  and  20 ′ and a skirt portion  21  therebetween. 
     A first supporter  23  substantially in an I-like shape is axially supported by the vertical wall portion  20  of the bracket  19  on one side by using a pin  22 . One end of a second supporter  24  substantially in an S-like shape is axially supported by the vertical wall portion  20 ′ on the other side by using a pin  25 . A small wheel  26  is attached between lower free end portions of the first and the second supporters  23  and  24 . 
     A guide pin  27  is fixed to an upper end portion of the second supporter  24  and the guide pin  27  is extended to the elongated hole  13  of the lower arm  3  via the can hole  16  of the operating member  14 . As a result, the second supporter  24  is pivoted around the pin  25  by changing the position of the guide pin  27  relative to the cam hole  16  and the elongated hole  13 . 
     The two supporters  23  and  24  are coupled by a connection plate  28  and accordingly, movement of the second supporter  24  simultaneously pivots the first supporter  23 . The movement of the two supporters  23  and  24  changes the position of the wheel  26  relative to the floor. 
     A state shown in FIG. 1 is a state in which by bringing down the seat back forwardly, the seat back frame  4  is made to push the contact piece  18  rearwardly, pivots the operating member in the clockwise direction, moves the guide pin  27  upwardly along the elongated hole  13 , as a result, the two supporters  23  and  24  are pivoted in the clockwise direction around the pins  22  and  25  and the wheel  26  is floated up from the floor. 
     Under the state in which the seat back is brought down, the seat can be folded forwardly by erecting the seat cushion centering on the hinge devices  5  by operating the lock devices  6 . Further, when the seat in the folded state is returned to a normal state, since the wheel  26  is floated up from the floor and accordingly, an operation for fixing the lock devices  6  to the floor can firmly be carried out. 
     When the seat back is returned to the seating position in the state of FIG. 1, contact of the seat back frame with the contact piece  18  is released and accordingly, by the urging force of the spring  29 , the operating member  14  is pivoted in the counterclockwise direction and the guide pin  27  changes its position in compliance with the long hole  13  and the cam hole  16 . Thereby, the two supporters  23  and  24  are pivoted in the counterclockwise direction centering on the pin  25  and the wheel  25  strongly presses the floor. In this way, the rigidity of the seat cushion frame is ensured. 
     Further, when the seat is moved in the forward and rearward direction, the wheel  26  per se rolls and assists movement of the seat. 
     As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.