Abstract:
In a vehicle seat ( 1 ), particularly a motor vehicle seat, having at least one bottom rail ( 21 ) to be connected to the vehicle chassis (S), at least one upper rail ( 22 ) displaceable in the seat longitudinal direction relative to the bottom rail ( 21 ) for the seat longitudinal adjustment, at least one fitting base ( 17 ), which is attached at least on the upper rail ( 22 ), and one backrest structure ( 14 ), which is attached by at least one fitting ( 15 ) in a manner that is pivotable about a backrest pivoting axis (C), the fitting base ( 17 ) is hinged on the upper rail ( 22 ) by a joint (E).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a United States National Phase application of International Application PCT/EP2008/000608 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2007 010 975.1 filed Mar. 1, 2007, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention pertains to a vehicle seat, particularly a motor vehicle seat. 
     BACKGROUND OF THE INVENTION 
     In a vehicle seat of this type known from use, the fitting lower part is attached to the upper rail by means of two formed feet. In the event of a crash, torques occur in this region which subject the upper rail to a load. In particular, in the extreme positions in the longitudinal direction of the seat, i.e. fully forwards and fully back, these crash torques may cause the risk that at one end the upper rail begins to separate from the lower rail as a result of material deformations. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to improve further a vehicle seat of the aforementioned type. 
     As the fitting lower part is articulated by means of a joint to the upper rail, in the event of a crash, torques may not be transmitted to the upper rail but only forces in the longitudinal direction of the seat or in the vertical direction which, however, intensify the bearing forces. In order to absorb these increased bearing forces, it is advantageous if the joint is arranged above rolling elements and/or a lock, provided between the lower rail and upper rail. 
     The prevention of torque transmission may be improved by the fitting lower part being articulated by means of a guide rod to the lower rail, so that additionally no torques may be transmitted to the lower rail. The guide rod provides the necessary longitudinal compensation during the relative displacement of the lower rail and the upper rail. 
     The vehicle seat preferably has a seat frame which at its front end is articulated to at least one rocker. As a particularity, the rocker is not articulated with its other end to the upper rail but articulated to the vehicle structure by means of a joint arranged fixed to the vehicle structure. In this case, the rocker may be directly articulated to the vehicle structure by means of this joint arranged fixed to the vehicle structure, for example to a bearing block or foot or the like, fixed to the vehicle structure. This variant is preferable. The rocker may, however, also be articulated indirectly to the vehicle structure, for example by the rocker being articulated to an intermediate structure of further gear members which in turn is articulated to the vehicle structure. 
     The seat frame is preferably articulated at its rear end to the backrest structure. With a longitudinal adjustment of the vehicle seat, the upper rails provided at the rear end of the vehicle seat are displaced relative to the associated lower rails, fixed to the vehicle structure, whilst the rockers provided at the front end pivot about the associated joints arranged fixed to the vehicle structure. As a result, the seat frame is moved as a whole in the longitudinal direction of the seat. The spacing between the joint of a rocker arranged fixed to the vehicle structure and the associated lower rail fixed to the vehicle structure remains constant. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective side view of the embodiment in a rear longitudinal position of the seat, with upholstery indicated in broken lines; and 
         FIG. 2  is a perspective side view corresponding to  FIG. 1  in a front longitudinal position of the seat. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, a vehicle seat  1 , for example for a rear seat row of a motor vehicle, is connected to the vehicle structure S of the motor vehicle. The arrangement of the vehicle seat  1  within the motor vehicle and the usual direction of travel thereof define the directional information subsequently used. The vehicle seat  1  comprises a seat frame  11  which at its front end is articulated on both vehicle seat sides by means of one respective rocker  13  to the vehicle structure S. Preferably, to this end, a bearing block or foot or the like is fastened to the vehicle structure S. The first joint defined by the articulation of the rocker  13  to the seat frame  11  is denoted by A, the second joint defined by the articulation of the rocker  13  to the vehicle structure is denoted by B. The second joint B is arranged fixed to the vehicle structure. 
     The vehicle seat  1  further comprises a backrest structure  14  which is attached on both vehicle seat sides by means of fittings  15  to fitting lower parts  17 . In this case, the backrest structure  14  is pivotable relative to the fitting lower parts  17  about a backrest pivot axis C by means of fittings  15 , when they are unlocked (in the case of an embodiment as detent fittings) or are driven (in the case of an embodiment as geared fittings). In the present case, the seat frame  11  is articulated to the backrest structure  14  with the ends of its side parts, by means of one respective third joint D on both vehicle seat sides. The third joint D is spaced apart from the backrest pivot axis C. The backrest structure  14  and the seat frame  11  are provided with cushions in a manner known per se. 
     The vehicle seat  1  comprises on both vehicle seat sides two seat rails, in the present case a lower rail  21  fastened to the vehicle structure S (i.e. fixed to the vehicle structure) and an upper rail  22  which is displaceable thereto and may be locked thereto. In the present case, the lower rail  21  and the upper rail  22  extend in the longitudinal direction of the seat only over a small region at the rear end of the vehicle seat  1 . 
     The fitting lower part  17  is articulated at its rear end by means of a fourth joint E to the upper rail  22 , for example approximately centrally and/or above the rolling elements conventionally provided between the lower rail  21  and the upper rail  22 , and/or above the lock between the lower rail  21  and the upper rail  22 . The fitting lower part  17  is articulated at its front end by means of a fifth joint F to a guide rod  25  which in turn is articulated by means of a sixth joint G to the lower rail  21 . 
     For a longitudinal seat adjustment, i.e. for the adjustment of the position of the vehicle seat  1  in the longitudinal direction of the seat, the upper rails  22  are unlocked and displaced relative to the lower rails  21 . By means of the fourth joint E, the sixth joint G and the fifth joint F a triangle is respectively defined which alters its shape during the longitudinal adjustment of the seat and thus displaces the respective fitting lower part  17  to the front or to the rear. As the fittings  15  remain locked and/or are not driven, the backrest structure  14  is also respectively displaced in the longitudinal direction of the seat to the front or to the rear with the fitting lower parts  17 . By means of the first joint A, the second joint B, the sixth joint G, the fifth joint F and the third joint D, a five-bar mechanism is respectively defined which also alters its shape during the longitudinal adjustment of the seat. In this case, preferably the seat frame  11  is displaced to the front or to the rear in the longitudinal direction of the seat. The rockers  13  pivot accordingly about the second joints B. With the longitudinal adjustment of the seat of the vehicle seat  1  and as a result of these movements of the multiple joints, the height of the seat frame  11  and the backrest structure  14  over the vehicle structure S is generally also altered, as well as the inclination of the seat frame  11  relative to the vehicle structure S. These movements are dependent on the ratio of the longitudinal adjustment path to the length of the rockers  13  and guide rods  25  and on the initial angular position of the rockers  13  and the guide rods  25 . 
     For adjusting the inclination of the backrest, the fittings  15  are unlocked and/or driven, whereby the backrest structure  14  is pivotable about the backrest pivot axis C. By means of the first joint A, the second joint B, the backrest pivot axis C and the third joint D, a four-bar linkage is defined which alters its shape during the adjustment of the inclination of the backrest. In this case, the seat frame  11  is displaced in the longitudinal direction of the seat slightly to the front or to the rear, and generally at the same time altered in its height and inclination relative to the vehicle structure S to a markedly lesser extent. 
     The vehicle seat  1  may also adopt a planar position of non-use, by the backrest structure  14  being pivoted to the front onto the seat frame  11 , beyond the region of adjustment of the inclination of the backrest, until it adopts an approximately horizontal position. In this case, the aforementioned four-bar linkage lowers the seat frame  11  downward during the pivoting forward of the backrest structure  14 . 
     In the event of a crash, forces are introduced via the backrest structure  14  and the fittings  15  into the fitting lower parts  17 . As the fitting lower parts  17  are attached in an articulated manner to the lower rails  21  and upper rails  22 , no torques may be transmitted, but only forces in the longitudinal direction of the seat and in the vertical direction. Thus the lower rails  21  and upper rails  22  are prevented from separating from one another, i.e. a deformation and moving apart of the profiles from one end of the rail, in particular when the vehicle seat  1  is located in the frontmost and rearmost longitudinal position of the seat. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.