Abstract:
A vehicle seat ( 1 ), in particular a commercial vehicle seat, is provided with a scissor-type stand ( 3 ) with a seat frame ( 10 ) that is articulated thereto by a pivoting axis (B), the seat frame being able to incline in relation to the scissor-type stand ( 3 ), and a back rest ( 20 ) that is attached to the seat frame ( 10 ). The seat frame ( 10 ) is articulated directly to the scissor-type stand ( 3 ) and is connected in an articulated manner to the scissor-type frame ( 3 ) by at least one three-hinged element.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a United States National Phase application of International Application PCT/PCT/EP2008/001224 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2007 009 170.4 filed Feb. 21, 2007, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a vehicle seat, in particular commercial vehicle seat, with a scissors-type stand, a seat frame which is coupled thereto by means of a pivot axis and which can be adjusted in its inclination relative to the scissors-type stand, and a backrest which is attached to the seat frame or to the scissors-type stand. 
     BACKGROUND OF THE INVENTION 
     Known vehicle seats with a scissors-type stand are generally used for commercial vehicles. While, in a simple embodiment, the seat frame is part of the scissors-type stand or is connected fixedly thereto, in order to increase the seat comfort the seat frame can be adjusted in inclination relative to the scissors-type stand, for example by the seat frame being coupled to the scissors-type stand and a linear adjuster or a gearing pivoting the seat frame relative to the scissors-type stand. A vehicle seat of the type mentioned at the beginning which is improved in such a manner is known from DE 32 43 747 C2. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of further improving a vehicle seat of the type mentioned at the beginning. 
     According to the invention, a vehicle seat, in particular commercial vehicle seat, is provided with a scissors-type stand, a seat frame which is coupled thereto by means of a pivot axis and which can be adjusted in its inclination relative to the scissors-type stand, and a backrest which is attached to the seat frame or to the scissors-type stand. The seat frame is coupled directly to the scissors-type stand and is connected in an articulated manner to the scissors-type stand by means of at least one triple-jointed element. 
     Owing to the fact that the seat frame is coupled directly to the scissors-type stand and is connected in an articulated manner to the scissors-type stand by means of at least one triple jointed element, a simply constructed inclination adjustment which takes place by driving the triple-jointed element is provided. The drive can take place using conventional driving devices, preferably an inclination-adjusting fitting which is provided in the triple-jointed element next to a link which is connected in an articulated manner to the inclination-adjusting fitting. The inclination-adjusting fitting may be a latching fitting or a geared fitting as is known per se for adjusting the inclination of the backrest. This reduces the costs. In this case, embodiments with disk-shaped units and embodiments with radially protruding fastening tabs are possible. 
     A first joint which is aligned with an inclination-adjusting axis defined by the inclination-adjusting fitting, and a further link can be provided on the vehicle seat side which is opposite the inclination-adjusting fitting. This reduces the number of components and also the costs. The inclination-adjusting axis and the two joints of the link preferably define the triple-jointed element. The geometry of the triple-jointed element is preferably optimized with regard to the moments which occur. Thus, for example, an axial offset between the pivoting planes of the joints, for example between the inclination-adjusting fitting or lever and the link, if, for example, a crosspiece is provided on both vehicle seat sides between inclination-adjusting fitting and lever, has the advantage that no bending moments are exerted on such a crosspiece. 
     The scissors-type stand preferably has a first catch element and the seat frame preferably has a second catch element, which catch elements normally do not interact and, in the event of a crash or misuse, approach each other because of a torque caused to act on the seat frame by means of the backrest, and then interact, in particular come into contact with each other, creating a further path for the force flux, and the forces are not only conducted via the deflecting point of the seat frame on the scissors-type stand and via the linear adjuster or the gearing, but also parallel thereto via the catch elements. There is therefore a better transmission of load from the seat frame to the scissors-type stand and/or the substructure, which permits the components which lie in the force flux parallel to the catch elements to be smaller and, as a result, overall reduces the production costs and the weight. This advantage is preferably reinforced in that the catch elements increase the supporting length by the catch elements being provided at a distance from the coupling point, for example at the end of the seat frame, if the latter is coupled centrally. In embodiments which are simple to produce, the catch elements are designed as angled stops, teeth, hooks, bolts, edges of openings or the like. 
     The invention is explained below in more detail with reference to two exemplary embodiments which are illustrated in the drawing. 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 partial view, which is common to both exemplary embodiments, without the upholstery; 
         FIG. 2  is a schematic side view which is common to both exemplary embodiments; 
         FIG. 3  is a side view, which is common to both exemplary embodiments, in a normal situation at an angle of inclination of 0° between the seat frame and scissors-type stand; 
         FIG. 4  is a side view corresponding to  FIG. 3  in the event of a crash; 
         FIG. 5  is a schematic illustration, which is common to both exemplary embodiments, of all of the joints; 
         FIG. 6  is a schematic illustration of the triple-jointed element; 
         FIG. 7  is a perspective partial view of the first exemplary embodiment on the vehicle seat side with the inclination-adjusting fitting; 
         FIG. 8  is a perspective partial view of the first exemplary embodiment on the opposite vehicle seat side; 
         FIG. 9  is a perspective partial view of the second exemplary embodiment on the vehicle seat side with the inclination-adjusting fitting; and 
         FIG. 10  is a perspective partial view of the second exemplary embodiment on the opposite vehicle seat side. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, a vehicle seat  1  for a commercial vehicle or another motor vehicle has a scissors-type stand  3  which comprises a bottom frame  5 , a top frame  7  arranged thereabove and a respective pair of crossed rockers  8  on both sides. A scissors axis A connects the two crossing points and at the same time defines the axis about which the rockers  8  can pivot relative to each other. The rockers  8  are each coupled at their rear end to the bottom frame  5  and to the top frame  7  and each have, at their front end, rotatable rollers by means of which they are guided movably in the longitudinal direction of the seat in or on the top frame  7  and bottom frame  5 . By means of said movement of the rockers  8 , the top frame  7  is adjusted in height over the bottom frame  5 . In the present case, the scissors-type stand  3  can be displaced in the longitudinal direction of the seat by means of seat rails  9 , thus enabling the vehicle seat  1  to be adjusted longitudinally, i.e. enabling the seat longitudinal position thereof to be adjusted. 
     The vehicle seat  1  furthermore has a seat frame  10  which is coupled on both sides to the top frame  7 —pivotably relative to the scissors-type stand  3  about a horizontal seat-frame pivot axis B. In the present case, said seat-frame pivot axis B—as seen in the longitudinal direction of the seat—is arranged somewhat behind the center of the seat frame  10 . At the front end of the seat frame  10 , a first joint  11  is provided on one vehicle seat side and, on the opposite vehicle seat side, an inclination-adjusting fitting  12  is provided in alignment with said joint. As an alternative, inclination-adjusting fittings  12  of the same type are provided on both vehicle seat sides. The inclination-adjusting fitting  12  has two fitting parts  12   a  and  12   b  which are rotatable relative to each other, thereby defining an inclination-adjusting axis N (which is in alignment with the first joint  11 ). The two fitting parts  12   a  and  12   b  can be locked to each other (latching fitting), as described, for example, in WO 00/44582 A1, the disclosure content of which in this regard is expressly incorporated, or are connected to each other in a geared manner (geared fitting), for example by means of a self-locking eccentric epicyclic gearing, as described, for example, in DE 44 36 101 A1, the disclosure content of which in this regard is expressly incorporated. 
     Inclination-adjusting fittings  12  of this type are known per se for adjusting the inclination of the backrest. 
     The first fitting part  12   a  of the inclination-adjusting fitting  12  is connected fixedly to the seat frame  10  while a first lever  13  is fastened to the second fitting part  12   b  (or alternatively is integrally formed thereon). In a manner described more precisely further on, a link  14  is connected in an articulated manner to the first lever  13 , said link having a second joint  14   a  for this purpose at its one end. The link  14  is coupled at its other end to the top frame  7  by means of a third joint  14   b . As a result, the inclination-adjusting axis N and the link  14  with its two coupling points  14   a  and  14   b  define a triple-jointed element. 
     A second lever  13   b  is provided on the other vehicle seat side, said lever, if, as in the present case, a first joint  11  which is aligned with the inclination-adjusting fitting  12  is provided, corresponding in its dimensions in the circumferential and radial direction (with respect to the first joint  11 ) to the second fitting part  12   b  together with the first lever  13 . In the alternative embodiment with a further inclination-adjusting fitting  12  on the other vehicle seat side, the second lever  13   b  is designed identically to or in a mirror-inverted manner to the first lever  13 . A further link  14  of identical construction, i.e. identical or mirror-inverted design, is coupled to the second lever  13   b  by means of the second joint  14   a  and to the top frame  7  by means of the third joint  14   b . In all cases, a triple-jointed element is therefore provided on both sides between the seat frame  10  and top frame  7 . 
     The inclination of the seat frame  10  relative to the top frame  7  and therefore relative to the scissors-type stand  3  can be adjusted by means of the inclination-adjusting fitting or the inclination-adjusting fittings  12  and the triple jointed elements. The inclination-adjusting fitting or the inclination-adjusting fittings  12  is or are driven in a manner known per se manually or by motor. The seat frame  10  bears a seat shell with a seat cushion in a manner known per se. 
     By means of a spring  15 , preferably a gas-filled spring, and preferably a damper, the scissors-type stand  3  is a rockable system which increases the seat comfort. 
     At the rear end, a respective backrest adaptor  16  is fastened on both sides to the seat frame  10  (or alternatively to the scissors-type stand  3 , in particular to the top frame  7  of the same). A backrest  20  is attached pivotably about a backrest pivot axis C to the backrest adaptors  16  by means of backrest fittings  22  provided on both sides. In a modified embodiment, the backrest  20  can be attached pivotably about the backrest pivot axis C directly to the seat frame  10  (or alternatively to the scissors-type stand  3 , in particular to the top frame  7  of the same) by means of the backrest fittings  22 . The backrest fittings  22  are driven manually or by motor. In a further modification, a backrest fitting  22  is provided only on one vehicle seat side and a joint is provided on the other vehicle seat side. 
     Like the inclination-adjusting fittings  12 , the backrest fittings  22  can be designed as latching fittings or geared fittings, preferably with a self-locking eccentric epicyclic gearing and, in terms of structure, can preferably form a disk-shaped unit. The backrest  20  can be pivoted relative to the seat frame  10  by means of the backrest fittings  22  and can be adjusted in its inclination. The backrest  20  is upholstered in a manner known per se. 
     A first catch element  31  is provided at the rear end of the top frame  7 —in the present case in each case on both vehicle seat sides—while a respective second catch element  32  is provided at the rear end of the seat frame  10  for interaction with each first catch element  31  provided. The catch elements  31  and  32  are spaced apart from the coupling point of the seat frame  10  to the top frame  7 . The two catch elements  31  and  32  on each vehicle seat side are arranged in such a manner that they normally do not interact. However, meshing or the like is possible. In the event of a head-on crash or severe misuse, when a force acts on the backrest  20  in the forward direction, a forwardly acting torque in the sense of a pivoting movement is caused by means of the backrest  20  to act on the seat frame  10 , which is attached to the backrest  20 , about the seat-frame pivot axis B. As a result, the seat frame  10 , which is coupled to the top frame  7  at the seat-frame pivot axis B, moves downward in direction at its front end and upward at its rear end. As a result, the second catch element  32  draws closer to the first catch element  31  and comes—in the present case at approximately 4° downward in relation to the horizontal—into contact with the first catch element  31 , i.e., in the event of a crash or the like, the two catch elements  31  and  32  interact. By means of said interaction and the further path for the force flux, better load transmission from the seat frame  10  to the scissors-type stand  3  takes place. 
     To this extent, the two exemplary embodiments coincide. 
     As already mentioned, inclination-adjusting fittings  12  as known for the adjustment of the inclination of the backrest are used for the triple-jointed elements. Such an inclination-adjusting fitting  12  can therefore have integrally formed fastening tabs protruding radially on the fitting parts  12   a  and  12   b  (and retaining clamps to axially hold together the fitting parts  12   a  and  12   b ), this being described as the first exemplary embodiment, or, in terms of structure, can form a disk-shaped unit (and have a clasping ring for the axial holding together), this being described as the second exemplary embodiment. In order to simplify the logistics, in each exemplary embodiment the backrest fittings  22  and the inclination-adjusting fittings  12  are preferably of the same type. 
     In the first exemplary embodiment, on the one vehicle seat side a crosspiece  40  is fastened (if appropriate by means of a further adaptor), preferably welded, to the first lever  13  which is preferably formed by the fastening tabs on the second fitting part  12   b  and the associated retaining clamp. The crosspiece  40 , for example a tube, is arranged parallel to the seat-frame pivot axis B and runs to the other vehicle seat side. The link  14  is coupled to the crosspiece  40  by means of the second joint  14   a  in a manner axially offset with respect to the first lever  13 . In this case, the axis of the inclination-adjusting fitting  12 , the second joint  14   a  and the crosspiece  40  mark the corners of a triangle, the geometry of which is optimized with regard to the driving moments in the triple-jointed element. 
     The second lever  13   b  is provided on the other vehicle seat side which has the first joint  11 , said lever being coupled to the seat frame  10  by means of the first joint  11  and likewise being fastened, preferably welded, to the crosspiece  40 . The first lever  13 , the second lever  13   b  and the crosspiece  40  therefore form a fixed constructional unit. Also on the vehicle seat side which has the first joint  11 , the link  14  is coupled to the crosspiece  40 , i.e. to said constructional unit, by means of the second joint  14   a  in a manner offset axially with respect to the second lever  13   b . The two links  14  are coupled by means of a respective third joint  14   b  to the top frame  7 , or more precisely to a—preferably slightly obliquely protruding—top-frame adaptor  7   a  of the top frame  7 . 
     The axial offset between the first lever  13  or second lever  13   b  and the link  14 , i.e. between the respective pivoting planes, along the crosspiece  40  (i.e. axially with respect to the inclination-adjusting axis N), assists in optimizing the geometry of the triple-jointed element, said offset being depicted as an axial offset between the fitting  12  or the first joint  11  and the second joint  14   a . Said axial offset has the advantage that bending moments are not exerted on the crosspiece  40 . 
     In the second exemplary embodiment, on the one vehicle seat side the first lever  13  is fastened to the second fitting part  12   b , for example at axially protruding back studs. The crosspiece  40 —in alignment with the inclination-adjusting axis N—is fastened to the second fitting part  12   b , for example to the axially protruding back studs by means of an adaptor, and if appropriate additionally (or alternatively) to the first lever  13 . On the other side, the crosspiece  40  is mounted rotatably in the seat frame  10  by means of the first joint  11 . The second lever  13   b  is fastened to the crosspiece  40  and corresponds in its dimensions and substantially in its configuration to the first lever  13 . The second fitting part  12   b , the first lever  13 , the second lever  13   b  and the crosspiece  40  therefore form a fixed constructional unit. The links  14  are in each case coupled directly to the first lever  13  or second lever  13   b  by means of the second joint  14   a  while they are coupled to the top frame  7  (not illustrated in  FIGS. 9 and 10 ) by means of the third joint  14   b.    
     While specific embodiments of the invention have been 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. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 List of designations 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                  1 
                 Vehicle seat 
               
               
                   
                  3 
                 Scissors-type stand 
               
               
                   
                  5 
                 Bottom frame 
               
               
                   
                  7 
                 Top frame 
               
               
                   
                  7a 
                 Top-frame adaptor 
               
               
                   
                  8 
                 Rocker 
               
               
                   
                  9 
                 Seat rail 
               
               
                   
                 10 
                 Seat frame 
               
               
                   
                 11 
                 First joint 
               
               
                   
                 12 
                 Inclination-adjusting fitting 
               
               
                   
                 12a 
                 First fitting part 
               
               
                   
                 12b 
                 Second fitting part 
               
               
                   
                 13 
                 First lever 
               
               
                   
                 13b 
                 Second lever 
               
               
                   
                 14 
                 Link 
               
               
                   
                 14a 
                 Second joint 
               
               
                   
                 14b 
                 Third joint 
               
               
                   
                 15 
                 Spring 
               
               
                   
                 16 
                 Backrest adaptor 
               
               
                   
                 20 
                 Backrest 
               
               
                   
                 22 
                 Backrest fitting 
               
               
                   
                 31 
                 First catch element 
               
               
                   
                 32 
                 Second catch element 
               
               
                   
                 40 
                 Crosspiece 
               
               
                   
                 A 
                 Scissors axis 
               
               
                   
                 B 
                 Seat-frame pivot axis 
               
               
                   
                 C 
                 Backrest pivot axis 
               
               
                   
                 N 
                 Inclination-adjusting axis