Abstract:
A vehicle seat ( 1 ), in particular a commercial vehicle seat, includes a scissor-type (scissors) framework ( 3 ) for adjusting the height. The scissors framework has intersecting rockers ( 8   a,    8   b ) and at least one frame ( 5, 7 ), and at least one bearing device ( 21 ) for movably guiding the rockers ( 8   a,    8   b ) in the frame ( 5, 7 ). A rotatable bearing roller ( 14 ) interacts with a first guide and a rotatable compensation roller ( 36 ) interacts with a second guide attached to a base region ( 52 ) of an insert ( 60 ). A lateral region ( 54 ) of the insert ( 60 ) extends perpendicularly to the base region ( 52 ) and is fixed to the frame ( 5, 7 ) and/or a head region ( 50 ) of the insert ( 60 ), extending parallel to the base region ( 52 ), is fixed to the frame ( 5, 7 ). The base region ( 52 ) is resiliently designed and presses against the compensation roller ( 36 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a United States National Phase Application of International Application PCT/EP2013/066955 filed Aug. 14, 2013 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Applications DE 10 2012 016 230.8 filed Aug. 14, 2012 and DE 10 2012 019 574.5 filed Sep. 26, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a vehicle seat, in particular a utility vehicle seat with a scissors-type (scissors) stand for adjusting the height, such a scissors stand having intersected rockers and at least one frame, and also a bearing device by means of which at least one of the rockers is guided movably in the frame, wherein the bearing device has a bearing roller which is rotatable about a bearing axis and which interacts with a first guide, and a compensating roller which is rotatable about the bearing axis and interacts with a second guide. 
     BACKGROUND OF THE INVENTION 
     A vehicle seat of the type in question which can be adjusted in height by means of a scissors stand is known from DE 10 2006 059 088 B4. 
     The scissors stand here comprises a lower frame, an upper frame arranged above the latter, and, on both sides, a respective pair of intersected rockers. The rockers of the scissors stand here are connected to each other in pairs by means of a plurality of transverse tubes. In the rear region of the vehicle seat, the rockers are articulated on the lower frame and on the upper frame by means of the transverse tubes. 
     Bearing devices by means of which the rockers are guided movably in the longitudinal direction in the upper frame and in the lower frame are provided in the front region of the vehicle seat. The bearing devices here in each case have two rotatable rollers which interact with guides in the upper frame and in the lower frame. 
     Upon a change in height of the scissors stand, the rollers roll in the longitudinal direction on corresponding guides in the upper frame and in the lower frame. In the process, in each case one of the rollers of a bearing device runs on an upper guide and the other of the rollers runs on a lower guide. 
     A vehicle seat of the type in question is also known from U.S. Pat. No. 6,200,032 B1. In order to reduce the play, in particular in the vertical direction, two rollers having different diameters are provided here, wherein the roller positioned on the inside has a larger diameter than the roller positioned on the outside. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of improving a vehicle seat of the type mentioned at the beginning, and in particular of indicating an alternative configuration in order to reduce play. 
     A vehicle seat of the type in question, in particular a utility vehicle seat, comprises a scissors stand for adjusting the height. The scissors stand has intersected rockers and at least one frame, and also a bearing device by means of which at least one of the rockers is guided movably in the frame. The bearing device has a bearing roller which is rotatable about a bearing axis and interacts with a first guide, and a compensating roller which is rotatable about the bearing axis and interacts with a second guide. 
     According to the invention, it is provided here that the second guide for the compensating roller is attached to a foot region of an insert, and in that a side region of the insert, which side region extends at a right angle to the foot region, is fastened to the frame, and/or in that a head region of the insert, which head region extends parallel to the foot region, is fastened to the frame, and in that the foot region is of elastically deformable design and presses against the compensating roller. 
     The foot region, owing to the elasticity thereof and prestressing by the second guide, presses here against the compensating roller, as a result of which the load roller is pressed against the first guide. As a result, play present between the guides and load roller and the compensating roller is reduced or eliminated. 
     Simple installation of the insert is produced if the frame has a C-shaped profile which is open toward the interior of the vehicle seat and comprises an upper limb, a lower limb running parallel to the upper limb and a base limb which runs at a right angle to the upper limb and connects the upper limb to the lower limb, wherein the side region is fastened, preferably welded, to the base limb, and/or the head region is fastened, preferably welded, to the upper limb. 
     For this purpose, the insert preferably likewise has an open C-shaped profile, as a result of which the installation is simplified even further. 
     The head region of the insert advantageously forms the first guide for the load roller here. 
     The alignment of the insert on the frame during installation is simplified by the fact that the head region runs parallel to the upper limb and bears tightly against the upper limb. 
     The foot region is advantageously arranged parallel or at least substantially parallel to the lower limb, wherein a gap is provided between the foot region and the lower limb. As a result, an elastic deformation of the foot region in the direction of the lower limb, and also in the direction away from the lower limb, is possible. 
     According to an advantageous configuration of the invention, the foot region comprises a first section which adjoins the side region, and a second section which faces away from the side region, wherein the second section is designed in the form of an embossed step and is arranged offset parallel to the first section. The embossed step here ensures the required distance between the first section of the load roller in order to avoid contact of the foot region with the load roller. 
     The second section here preferably also forms the second guide for the compensating roller. 
     According to a further advantageous configuration of the invention, a support which forms the second guide for the compensating roller is mounted on the foot region. In this case, the support ensures the required distance between the first section and the load roller in order to avoid contact of the foot region with the load roller. 
     The insert is preferably composed of metal, preferably of steel. This permits welding of the insert to the frame and at the same time provides the foot region with the required elasticity. 
     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 schematic illustration of a vehicle seat; 
         FIG. 2  is a perspective illustration of a vehicle seat without seat part; 
         FIG. 3  is a section through a bearing device according to a first exemplary embodiment perpendicularly to the longitudinal direction; 
         FIG. 4  is a frontal view of a bearing device according to the first exemplary embodiment, as seen in longitudinal direction; 
         FIG. 5  is a section through a bearing device according to a second exemplary embodiment perpendicularly to the longitudinal direction; 
         FIG. 6  is a frontal view of a bearing device according to the second exemplary embodiment, as seen in longitudinal direction; 
         FIG. 7  is a section through a bearing device according to a third exemplary embodiment perpendicularly to the longitudinal direction; 
         FIG. 8  is a frontal view of a bearing device according to the third exemplary embodiment, as seen in longitudinal direction; 
         FIG. 9  is a perspective illustration of a bearing device according to the third exemplary embodiment; and 
         FIG. 10  is a perspective illustration of two bearing devices on upper frame and lower frame of a vehicle seat. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A vehicle seat  1  for a utility vehicle has a scissors stand  3 , which comprises a lower frame  5 , an upper frame  7  arranged above the latter, and, on both sides, a respective pair of intersected first rockers  8   a  and second rockers  8   b . A transverse tube  9  connects the two intersections and at the same time defines a scissors axis about which the rockers  8   a  and  8   b  can pivot relative to each other. 
     The arrangement of the vehicle seat  1  inside the vehicle and the usual direction of travel of the latter define the directional information used below. A direction oriented perpendicular to the ground is designated below as the vertical direction, and a direction perpendicular to the vertical direction and perpendicular to the direction of travel is designated below as the transverse direction. 
     The first rockers  8   a  are connected to each other at their rear ends by means of a holding tube  18  and are articulated on the upper frame  7 . At their front ends, the first rockers  8   a  are connected by means of a bearing tube  20  and are guided movably on both sides, by means of a respective bearing device  21  in the lower frame  5 , in the longitudinal direction, which corresponds approximately to the direction of travel. 
     The second rockers  8   b  are connected to each other at their rear ends by means of a holding tube  18  and are articulated on the lower frame  5 . At their front ends, the second rockers  8   b  are likewise connected by means of a bearing tube  20  and are guided movably on both sides, by means of a respective bearing device  21  in the upper frame  7 , in the longitudinal direction. 
     The transverse tube  9 , the bearing tubes  20  and the holding tubes  18  extend in the present case in the transverse direction, likewise the scissors axis. By means of a pivoting movement of the first rockers  8   a  relative to the second rockers  8   b  about the scissors axis, the height of the upper frame  7  over the lower frame  5 , referred to below for short as height of the scissors stand  3 , is modified. By means of a pneumatic spring  12  and preferably a damper (not shown here), the scissors stand  3  becomes an oscillating system, which greatly increases the seat comfort. 
     The vehicle seat  1  also has a seat frame  6  which, on the one hand in its rear area, is articulated on the upper frame  7  on both sides and, on the other hand in its front area, can be raised and lowered by means of an inclination adjuster and is thus adjustable in terms of its inclination relative to the scissors stand  3 . 
     The vehicle seat  1  also has a backrest  10  which, in the present case, is mounted adjustably in inclination on the seat frame  6 . Alternatively, the backrest  10  can also be mounted on the upper frame  7 . The backrest  10  is lined with a cover  28 . A head rest  40  is provided in what is, in the vertical direction, an upper area of the backrest  10 . The backrest  10  and the seat frame  6 , which comprises a seat cushion, form a seat part  2 . 
     Together with the scissors stand  3 , the seat part  2  is displaceable by means of two pairs of rails, whereby the vehicle seat  1  is adjustable in translation in the longitudinal direction, which corresponds approximately to the direction of travel. The two pairs of rails are offset in relation to each other in the transverse direction and are arranged parallel to each other. The two pairs of rails are of substantially identical construction. 
     Each pair of rails comprises a first seat rail  45 , which is also designated as upper rail, and a second seat rail  46 , which is also designated as lower rail. The second seat rail  46  is in the present case rigidly connected to the structure of the vehicle, and the first seat rail  45  is rigidly connected to the lower frame  5  of the vehicle seat  1 . Alternatively, it is conceivable to connect the second seat rail  46  to the structure of the vehicle by means of an adapter or a console. It is also conceivable to connect the first seat rail  45  to the lower frame  5  of the vehicle seat  1  by means of an adapter. 
     The first seat rail  45  is guided movably relative to and within the second seat rail  46 . By means of a locking device, the first seat rail  45  can be locked with the second seat rail  46 . An unlocking unit, which comprises an unlocking bar  44 , serves to unlock the locking device. 
     The unlocking bar  44  is arranged in what is a front area of the vehicle seat  1  as seen in the direction of travel, or the longitudinal direction, and is mounted pivotably about a pivot axle, which in the present case extends in the transverse direction. By pulling the unlocking bar  44  upward in the vertical direction, it is pivoted about the pivot axle, as a result of which the locking device is unlocked. 
     The unlocking lever  44  and the pivot axle are assigned kinematically to the lower frame  5  and to the first seat rail  45 . This means that, during a displacement of the seat part  2  in the longitudinal direction, the unlocking lever  44  accordingly moves along too, but not in the case of a change of height of the scissors stand  3 , i.e. during a movement of the seat part  2  in the vertical direction. 
     Those parts of the upper frame  7  and of the lower frame  5  that extend in the longitudinal direction each have a C-shaped profile open toward the interior of the vehicle seat  1 . Each bearing device  21  has a load roller  14 , which is mounted rotatably about a bearing axle  16  extending in the transverse direction and which protrudes into an open C-shaped profile of the upper frame  7  or of the lower frame  5 . 
     The C-shaped profile of the upper frame  7  and the C-shaped profile of the lower frame  5  each have an upper limb  30  and a lower limb  32 , which is arranged underneath the upper limb in the vertical direction. The upper limb  30  and the lower limb  32  extend parallel to each other, and they are connected to each other by a base limb  34  extending at right angles to them. Thus, the upper limb  30 , the lower limb  32  and the base limb  34  form a C-shaped profile in cross section. 
     The load roller  14  of the bearing device  21  is mounted rotatably here on a cylindrical bearing shaft  24 . The bearing shaft  24  is fixedly connected to the bearing tube  20 , wherein the center axes of the bearing tube  20  and of the bearing shaft  24  are aligned with each other and form the bearing axis  16  of the load roller  14 . In the present case, the load roller  14  is of approximately cylindrical design. 
     Furthermore, a compensating roller  36  is mounted on the cylindrical bearing shaft  24  so as to be rotatable about the bearing axis  16 . In the present case, the compensating roller  36  is also of approximately cylindrical design. In the present case, the compensating roller  36  has the same diameter as the load roller  14 . 
     In the present case, the load roller  14  is arranged on the bearing shaft  24  on the outside in the transverse direction, i.e. facing the base limb  34  of the C-shaped profile. The compensating roller  36  is arranged on the bearing shaft  24  on the inside in the transverse direction, i.e. facing the bearing tube  20 . 
     Inserts  60  which likewise have an approximately C-shaped cross section are introduced in each case within the C-shaped profiles of the upper frame  7  and of the lower frame  5 . Each insert  60  here has a head region  50 , a foot region  52  and a side region  54  which is connected to the head region  50  and the foot region  52 . The head region  50  here is arranged parallel to the upper limb  30 , the foot region  52  is arranged substantially parallel to the lower limb  32  and the side region  54  is arranged parallel to the base limb  34  of the C-shaped profile. 
     The head region  50  bears tightly against the upper limb  30 , while a gap is provided between the foot region  52  and the lower limb  32 . The side region  54  is welded to the base limb  34  of the C-shaped profile, in the present case by means of laser welding. 
     The foot region  52  comprises a first section  62  which adjoins the side region  54 , and a second section  64  which adjoins the first section  62  and faces away from the side region  54 . The first section  62  and the head region  50  are arranged here approximately opposite each other in the vertical direction and facing each other. 
     According to a first exemplary embodiment illustrated in  FIG. 3  and  FIG. 4  and according to a second exemplary embodiment illustrated in  FIG. 5  and  FIG. 6 , the second section  64  is designed in the form of an embossed step and lies approximately parallel to and offset in the vertical direction with respect to the first section  62 . The first section  62  here is located closer to the lower limb  32  than the second section  64 . 
     The head region  50  forms a first guide for the load roller  14 , and the second section  64  of the foot region  52  forms a second guide for the compensating roller  36 . It is ensured by the shape of the embossed step that the compensating roller  36  is in contact with the second section  64  of the foot region  52  while the load roller  14  is spaced apart in the vertical direction from the first section  62  of the foot region  52 . 
     In the present case, the insert  60  is composed of steel and is therefore elastic. In particular, the foot region  52  is elastic and therefore acts similarly to a spring. The second section  64  here presses upward in the vertical direction against the compensating roller  36 . The load roller  14  is pressed upward here against the head region  50 . 
     It is thus ensured that the compensating roller  36  and the load roller  14  are constantly in contact with the corresponding guides and bear against the first guide and against the second guide. As a result, component tolerances can be compensated for and play in the vertical direction is eliminated. 
     According to the first exemplary embodiment illustrated in  FIG. 3  and  FIG. 4 , an enlarged portion  72  mounted on the load roller  14  serves to compensate for play in the transverse direction. The enlarged portion  72  is located here on that end side of the load roller  14  which faces the side region  54  of the insert  60 , and projects in the transverse direction beyond the rest of the load roller  14 . The enlarged portion  72  bears here against the side region  54  of the insert  60 . In the present case, the enlarged portion  72  is designed as a camber, which is in the shape of a spherical section, of the end side of the load roller  14 . Other configurations are also conceivable. 
     According to the second exemplary embodiment illustrated in  FIG. 5  and  FIG. 6 , a sliding element  70  which is inserted into a bearing bore in the bearing shaft  24 , the bearing bore running in the transverse direction, is provided in order to compensate for play in the transverse direction. The sliding element  70  bears here against the side region  54  of the insert  60 . 
     According to a third exemplary embodiment illustrated in  FIG. 7 ,  FIG. 8  and  FIG. 9 , the second section  64  adjoins the first section  62  rectilinearly. A support  66  is mounted, in the present case adhesively bonded, on the second section  64  of the foot region  52 , the support  66  forming the second guide for the compensating roller  36  while the head region  50  forms the first guide for the load roller  14 . The support  66  ensures that the compensating roller  36  is in contact with the second guide while the load roller  14  is spaced apart in the vertical direction from the first section  62  of the foot region  52 . 
     In the present case, the second support  66  is composed of a hard plastic which is not elastic or is elastic only to a small extent. It is also conceivable for the support  66  to be composed of an elastic material, for example rubber. 
     The insert  60  is also composed of steel, and is therefore elastic, in the third exemplary embodiment. In particular, the foot region  52  is elastic and therefore acts in a similar manner to a spring. The second section  64  presses upward here with the support  66  in the vertical direction against the compensating roller  36 . The load roller  14  is pressed upward here against the head region  50 . 
     It is thus also ensured in the third exemplary embodiment that the compensating roller  36  and the load roller  14  are continuously in contact with the corresponding guides and bear against the first guide and against the second guide. As a result, component tolerances can be compensated for and play in the vertical direction is eliminated. 
     According to the third exemplary embodiment illustrated in  FIG. 7 ,  FIG. 8  and  FIG. 9 , a sliding element  70  which is inserted into a bearing bore in the bearing shaft  24 , which bearing bore runs in the transverse direction, and bears against the side region  54  of the insert  60  serves to compensate for play in the transverse direction, in a similar manner as in the second exemplary embodiment illustrated in  FIG. 5  and  FIG. 6 . 
     In a similar manner as in the first exemplary embodiment illustrated in  FIG. 3  and  FIG. 4 , it is also conceivable, in order to compensate for play in the transverse direction, to provide an enlarged portion on the load roller  14 , which enlarged portion is located on that end side of the load roller  14  which faces the side region  54  of the insert  60 , and projects in the transverse direction beyond the rest of the load roller  14 . The enlarged portion then bears against the side region  54  of the insert  60 . 
     In the exemplary embodiments described here, the bearing devices  21  which interact with the lower frame  5  correspond in design and function to the bearing devices  21 , which are described here, on the upper frame  7 .  FIG. 7  illustrates part of a vehicle seat with bearing devices  21  on the upper frame  7  and on the lower frame  5 . 
     The features disclosed in the above description, the claims and the drawings may be of significance both individually and in combination for realizing the invention in the various configurations thereof. 
     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.