Abstract:
An adjustable vehicle seat comprises a seat cushion positioned on both a seat-shell front part and a seat-shell rear part. The seat-shell front part is formed separately from the seat-shell rear part and mounted for moving relative to the seat-shell rear part, so that the seat-shell front part can be adjusted relative to the seat-shell rear part. As a result of the fact that the seat-shell front part and the seat-shell rear part are formed separately, and the seat-shell front part can be adjusted, in particular independently of the seat-shell rear part, the seat-shell front part can be adapted individually to the seat user in inclination and/or length of the seat surface.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an adjustable vehicle seat, in particular for a truck, having at least one structurally fixed part and at least one adjustable part which is movable relative to the structurally fixed part. 
     A known vehicle seat of this type has a one-piece seat shell on a seat frame which can be adjusted in its entirety, for example vertically by means of a scissors-type substructure. 
     It is an object of the present invention to provide an improved adjustable vehicle seat of the type mentioned at the beginning. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, an adjustable vehicle seat comprises a seat cushion positioned on both a seat-shell front part and a seat-shell rear part. The seat-shell front part is formed separately from the seat-shell rear part and mounted for moving relative to the seat-shell rear part, so that the seat-shell front part can be adjusted relative to the seat-shell rear part. 
     As a result of the fact that the seat-shell front part and the seat-shell rear part are formed separately, and the seat-shell front part can be adjusted, in particular independently of the seat-shell rear part, the seat-shell front part can, for example, be adapted individually to the seat user in inclination and/or length of the seat surface. This increases the comfort. The seat surface is defined between the front edge of the seat cushion and the backrest. For a thigh support, it is sufficient if only the seat-shell front part is adjustable and the seat-shell rear part remains fixed, for example as part of a seat frame. It is advantageous for the seat cushion to rest on the seat-shell rear part and be fastened to the seat-shell front part. When the seat-shell front part is adjusted, the seat cushion can then move in a corresponding manner at the same time. In order to enable adjustment in a gap-free manner with the various seat-surface lengths, the seat cushion reaches, for example, a small distance below the backrest. The vehicle seat according to the invention can be used not only in the case of trucks, including coaches, but also in other types of vehicles. 
     In one preferred embodiment of the present invention, the seat-shell front part can be pivoted relative to the seat-shell rear part in order to adjust its inclination, for example by the seat-shell front part being arranged on a carrier plate which is coupled to the seat frame. The adjustment of the inclination preferably takes place pneumatically via an inflatable cushion which is arranged between the carrier plate and the seat frame. An embodiment of this type can be produced with little outlay on material and in terms of time and is thereby cost-effective. For the pneumatic actuation, the system can be connected to the compressed-air supply of the truck. However, the adjustment of the inclination can also take place hydraulically, electromechanically or manually. 
     In another preferred embodiment of the present invention, the seat-shell front part can be displaced relative to the seat-shell rear part in order to adjust the seat-surface length, for example by the seat-shell front part being displaceable relative to the carrier plate and being lockable. As a result and for example, a multi-adjustable vehicle seat is provided with few components. For reliable guiding during the seat-surface length adjustment, slideways are provided on the seat-shell front part and/or on the carrier plate. The seat-shell front part is preferably locked by means of a locking bar which is mounted movably on the carrier plate, is movable relative to the seat-shell front part and, for locking purposes, interacts with a toothed segment of the seat-shell front part. This makes reliable locking and easy unlocking possible. For better performance during a crash, the locking bar is advantageously movable transversely to the seat longitudinal direction. The locking bar can likewise be actuated pneumatically by the existing compressed-air supply. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention is explained in more detail with reference to an exemplary embodiment illustrated in the drawings, in which: 
     FIG. 1 shows a schematic side view of a vehicle seat according to one exemplary embodiment of the invention, 
     FIG. 2 shows a perspective view of a seat frame, 
     FIG. 3 shows a plan view of a carrier plate in the direction of the arrow III in FIG. 4, 
     FIG. 4 shows a front view of the seat frame and carrier plate in the direction of the arrow IV in FIGS. 2 and 3, and 
     FIG. 5 shows a perspective view of a seat-shell front part. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with one exemplary embodiment, a vehicle seat  1  is fitted in a truck as a driver&#39;s seat. The following directional indications refer to the orientation specified by the normal direction of travel. The vehicle seat  1  is provided with a steel seat frame  3  which has two parallel side parts  5 , which are arranged in the longitudinal direction, have an essentially U-shaped profile, and are designed such that they are upwardly open; a planar connecting plate  7 , which is arranged transversely to the side parts and connects the two side parts  5  in the front region on the upper side; an at least partially planar seat-shell rear part  9 , which is arranged transversely to the two side parts  5  and connects the two side parts  5  in the rear region on the upper side; and two fastening plates  11  which are mounted laterally on the seat-shell rear part  9 . The side parts  5  are connected on their lower side to the vehicle structure. The fastening plates  11  are provided with holes and welded-on nuts or with threaded holes in order to fasten a backrest structure to the seat frame  3 . 
     On each limb of their U-shaped profile, the side parts  5  each have a hole  5 ′ which is arranged, in the longitudinal direction, approximately in the center of the corresponding side part  5 . The four holes  5 ′ in total are all aligned transversely to the longitudinal direction and are flush with one another. A respective bearing bush  12  is inserted between the two holes  5 ′ of each side part  5 . A respective bearing bolt  13  is pushed through each bearing bush  12  and the relevant two holes  5 ′ and is secured at its ends. The two bearing bushes  12  can be rotated relative to the two side parts  5  and the two bearing bolts  13 . 
     An essentially planar carrier plate  16  has, on its lower side, two parallel U-profiles  18  running in the longitudinal direction. At its rear end, in the region of the rear edge of the carrier plate  16 , one of the bearing bushes  12  is in each case inserted through each U-profile  18  and fastened. The carrier plate  16  can thereby be pivoted relative to the seat frame  3 , the U-profile  18  at least partly fitting into the front half of the corresponding U-shaped profile of the side parts  5 . 
     An inflatable cushion  21  is provided between the connecting plate  7  and the carrier plate  16 , which cushion is connected via a connection to the compressed-air supply of the truck. By admission of compressed air, the cushion  21  can raise the carrier plate  16  and initiate a pivoting movement of the carrier plate  16 , as a result of which the front edge of the carrier plate  16  is raised. Releasing compressed air out of the cushion  21  enables the carrier plate  16  to be lowered again. The releasing of the compressed air is assisted by the body weight of the seat user. 
     On its upper side, the carrier plate  16  has a respective slideway  24  above each U-profile  18 . An essentially planar seat-shell front part  26 , which is made of sheet metal and has a rounded front edge and raised border to the side and toward the front in order to attach the cover, has two parallel sliding fixtures  28  which are punched out of the material of the seat-shell front part  26 . Each sliding fixture  28  holds a slideway  24 . As a result, the seat-shell front part  26  can be displaced in the longitudinal direction relative to the carrier plate  16 . 
     In order to secure a selected longitudinal adjustment of the seat-shell front part  26 , the latter has, below an upwardly bent tooth covering  30 , a toothed segment  32  whose teeth face toward the inside of the vehicle seat  1 , i.e. toward the right seat side in the exemplary embodiment. The toothed segment  32  interacts with a movable locking bar  34 . The locking bar  34  has a flat, elongated basic shape in the manner of a strip, the end sections  34 ′ and  34 ″ being bent upward or downward at right angles with respect to the basic shape. 
     The locking bar  34  is arranged and mounted movably on the lower side of the carrier plate  16  transversely to the longitudinal direction of the vehicle seat  1  between the center and the left seat side. The carrier plate  16  has two side guides  36  and a retaining guide  38 , arranged between the side guides  36 , the guides in each case being produced by pressing out of material, or else may be formed as a separate plastic part. The side guides  36  and the retaining guide  38  hold the locking bar  34  and are aligned in such a manner that the locking bar  34  is easily movable with little play. The side guides  36  are responsible for guiding in the plane parallel to the carrier plate  16  while the retaining guide  38  bears the weight of the locking bar  34  and keeps the latter bearing against the carrier plate  16 , i.e. is responsible for guiding perpendicularly to the plane of the carrier plate  16 . 
     The upwardly bent end section  34 ′ of the locking bar  34  protrudes as far as the upper side of the carrier plate  16  through the side guide  36 , which is situated further inward, or through an adjacent aperture  40  of the carrier plate  16 , the aperture  40  being provided for installation of the locking bar  34 . This end section  34 ′ is provided with a latching opening or the like with which it can interact with one of the teeth of the toothed segment  32 . The downwardly bent end section  34 ″ of the locking bar  34  is arranged a sufficient distance on the left border of the carrier plate  16  that it comes to lie outside the side parts  5  irrespective of the pivoting position of the carrier plate  16 . 
     By admission of compressed air to a pneumatic actuator  35 , which is illustrated schematically in FIG.  4  and is positioned proximate the end section  34 ″, the locking bar  34  can be pressed away inward by a tooth of the toothed segment  32 , so that the seat-shell front part  26  is unlocked and can be displaced with respect to the carrier plate  16  and can be adjusted in length. The locking bar  34  is pushed back outward by spring force, thereby locking the toothed segment  32  and therefore securing the seat-shell front part  26  on the carrier plate  16 . 
     The front part of a seat cushion  42  is mounted on the seat-shell front part  26 . A panel (not illustrated in the drawing) made of plastic is mounted along the border of the carrier plate  16 . The rear part of the seat cushion  42  rests loosely on the seat-shell rear part  9 . A backrest, which is only outlined in FIG. 1, is arranged above the rear end section of the seat cushion  42 . The seat cushion  42  is sufficiently long that, even when the length of the seat surface is at its largest, there is still no vertical gap between the seat cushion  42  and backrest. The described pivoting of the carrier plate  16  by means of the cushion  21  enables the seat-surface inclination of the seat cushion  42 , in particular the thigh support, to be pneumatically adjusted. The described displacement of the seat-shell front part  26  and the pneumatic unlocking and locking by means of the locking bar  34  enable the seat-surface length of the seat cushion  42  to be adjusted. The wiring and valve system necessary for the pneumatic adjustment is not illustrated in the drawing. 
     Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.