Abstract:
The invention relates to a vehicle seat with a back rest having a frame ( 2 ) and a lordosis support ( 6 ), with the following additional configuration: The lordosis support ( 6 ) comprises a pressure plate ( 9 ) that is essentially bend resistant in at least the transverse direction of the seat or the Y-direction, forms a supporting surface in the lordosis region of the back rest and is arranged between two side frame parts ( 3 ) of the frame ( 2 ); there is at least one holding element ( 5   a,    5   b ) that extends between the side frame parts ( 3 ) with a length-variable adjustment section ( 21 ), which runs in the Y-direction and connects to the pressure plate ( 9 ), and is affixed there at fixing points ( 30 ) arranged opposite each other; in an inoperative position, the pressure plate ( 9 ) is arranged with a horizontal clearance ( 11 ) or a clearance in the X-direction behind the fixing points ( 30 ); there is a driving device with which the length of the adjustment section can be shortened as the horizontal clearance is reduced.

Description:
FIELD OF THE INVENTION 
     The invention relates to a vehicle seat with lordosis support. 
     BACKGROUND 
     A lordosis support is a device arranged near the surface in the back rest of a seat, with which the contour of the back rest can be adjusted in the lordosis region of the user. For this purpose, air bubbles, which can be inflated or deflated in order to adjust the seat contour, are frequently arranged under the upholstery of the back rest. There are also existing mechanical solutions, that is, those that adjust the contour of the seat by purely mechanical means, as in the vehicle seats disclosed in U.S. Pat. Nos. 6,601,919 B1, 5,474,358, 6,767,214 B2, 6,814,407 B2, and 6,652,028 B2. The known vehicle seats have a supporting element in the lordosis region behind the back rest cushioning. This is curved in either the transverse or longitudinal direction of the seat by a motor-driven device that is generally aided by a Bowden cable. By this means, the original seat contour, that is, its non-curved state, is changed considerably, which is often not desirable. Another disadvantage is that, due to its curving, the supporting element causes a relative movement to the cushioning, as, for example, in the case of U.S. Pat. No. 6,814,407 B2. In the vehicle seat described therein, a supporting element extends in the transverse direction of the seat. The curving is achieved by bringing the ends of the supporting element close together using a Bowden cable, and this necessarily causes a relative movement to the back-rest cushioning. 
     SUMMARY 
     The task of the disclosure is to propose a vehicle seat with lordosis support in which the seat contour is adjusted in the lordosis region using alternative means, thereby avoiding the specified disadvantages. 
     This task is fulfilled by a vehicle seat according to certain aspects of the disclosure. According to one aspect, the lordosis support comprises a bend-resistant pressure plate in essentially the transverse direction of the seat which forms a supporting surface in the lordosis region of the back rest and is arranged between two side frame parts of the seat frame, wherein there is at least one holding element that extends between the frame parts with a length-variable adjustment section, which runs in the Y-direction and supports the pressure plate, and is affixed there at fixing points arranged opposite each other. In an inoperative position, the pressure plate is arranged with a horizontal clearance behind the fixing points, wherein there is a driving device with which the length of the adjustment section can be shortened as the horizontal clearance is reduced. The shortening of the adjustment section moves the pressure plate forward, thus curving the cushioning of the back rest. Due to the rigidity of the seat plate, the contour of the lordosis region of the back rest remains essentially unchanged during this process. In contrast, for example, in the seats known from U.S. Pat. No. 6,676,214 B2, the element effecting the curving is flexible, so that changes to the contour of the lordosis region of the back rest depend upon the degree of the curving. The at least one holding element runs preferably along the back side of the pressure plate, so that the plate can securely brace itself against the holding element when the seat is supporting a passenger&#39;s weight. Furthermore, with the specified arrangement, one avoids a relative movement between the back rest cushioning and the holding element, which is being shortened or moved back into its starting position. 
     By providing two holding elements that are spaced apart from each other in the vertical direction, the design achieves both a curve in the lordosis region and a curving movement in the vertical direction, that is, from the bottom to the top and vice versa. Lordosis supports with this type of flexibility may be considered to provide a 4-way lordosis support. The vertical curving movement of the back rest in the lordosis region is achieved by simply shortening and controlling the holding elements independent of each other and time-delayed. 
     In the case of a single holding element, as well as two holding elements, the pressure plate is reset to its starting position by the weight of the seat&#39;s user and also by the tension increasing in the cushioning and the back rest covering when the contour of the back rest is curved. Thus, the holding element can also be reset to its starting position, that is, it can be lengthened after it was previously shortened. Preferably, the holding element comprises a spring element. This increases the seat&#39;s comfort and also acts as an overload element. 
     In an embodiment, a holding element comprises two spring elements, each of which has a first and a second end, wherein the first end is always affixed to a side frame part and the second ends are connected to each other via a connecting element whose length can be reduced using a driving device. When the length of the connecting element is reduced, the adjustment region of the holding element is shortened and the pressure plate is moved forward accordingly. 
     In a first variant, the connecting element is a Bowden cable made of an internal cable and a casing. The casing is braced against the second end of one of the spring elements, wherein the end of a section of the internal cable, which protrudes from the casing, is affixed to the second end of the other spring element. In this manner, which is technically easy to implement, the second ends of the spring elements can thus be brought close together or, respectively, the adjustment section of the holding element extending between the side frame parts of the back rest can be shortened. 
     In a second variant, the connecting element is essentially composed of a motor-driven turnbuckle whose ends are connected with the helical extension springs. Particularly with respect to the technical assembly issues, it is advantageous if at least one unit comprising a turnbuckle and a motor is arranged in a shared housing affixed to the back side of the pressure plate. 
     In order to affix the pressure plate on the holding element, the design provides a receptacle on the back side of the pressure plate which extends over at least part of the width of the pressure plate and in which the internal cable of the Bowden cable is guided basically free of backlash. This prevents the internal cable from vibrating during vehicle operation, which can lead to body rattle. 
     The curving area in the lordosis region of the back rest does not extend over the entire width of the back rest, but is rather limited to a middle section of the back rest. Accordingly, the pressure plate does not fill the entire available space between the side frame parts in the transverse direction of the vehicle; rather, there is a space between the pressure plate and the aforementioned frame parts. As already mentioned above, the pressure plate is hung on the side frame parts with the spring elements. If the spring elements are helical extension springs, as is provided in one design, there is the risk that the spring elements, which work in the transverse direction of the seat, will damage the cushioning material. In order to avoid this, appendages, which extend in the transverse direction of the seat and at least partially cover the spring elements, are attached to the side edges of the pressure plate. 
     When the adjustment section of the holding element is shortened, the pressure plate is moved forward, thus increasing the angle that is formed by the holding element sections extending between the side frame parts and the side edges of the pressure plate, that is, especially the spring elements with the planar level of the pressure plate. In order to change the angularity of the aforementioned holding element section during the forward and backward movement of the pressure plate in an essentially unimpeded manner, the appendages are hinged to the pressure plate in such a way that their angularity to the planar level of the pressure plate can be changed. This is ensured, for example, in that either the appendages are designed to be completely flexible or only the connection between the appendages and the pressure plate is designed to be flexible. It is conceivable, for example, that the appendages are formed over a film hinge, that is, a thinned area of material on the pressure plate. A cross connection of the appendages and the spring elements, particularly those designed as helical extension springs, is ensured by having a receptacle on the back sides of the appendages that holds a spring element which has a positive locking that works only in the longitudinal direction of the vehicle. This guarantees coupling of motion between the spring element and the appendage during a forward or return stroke of the pressure plate, without the relative mobility between the appendage and spring element thereby being compromised in the transverse direction of the seat. 
     In the area of the back rest located above the pressure plate, another plate is affixed to the frame and serves to support the back rest cushioning; the plate is therefore hereinafter referred to as the supporting plate. It is, of course, conceivable for the supporting plate to be a part that is independent of and separate from the pressure plate. In one design, however, the supporting plate is connected to the upper edge of the pressure plate. This increases the stability of the entire back rest structure, wherein a flexible mounting is ensured by the supporting plate being affixed to the side frame parts with spring elements, particularly helical extension springs. In order to guarantee an essentially independent adjustment of the pressure plate despite the connection of the two plates, in one embodiment, the supporting plate is hinged to the pressure plate, for example, it is connected to the pressure plate by a hinged joint. Alternatively, or in addition to this embodiment, the supporting plate is designed to be somewhat flexible in the vertical direction, for example, using through holes or an appropriate material strength. 
     In another embodiment, on the back side of the pressure plate and/or the supporting plate, at least one fan is arranged whose exhaust opening penetrates the supporting plate or the pressure plate. In this way, the back rest can be cooled or warmed, especially in the lordosis region, by blowing in warm or cold air. 
     A driving device for a holding element, which is generally an electric motor that is equipped, if necessary, with a gearbox, can be attached to the side frame parts. In one embodiment, however, the drive is arranged on the back side of the pressure plate or the supporting plate. This is advantageous in that the pressure plate, along with all required components, such as, the holding element, spring elements, mounting plate, and driving device, can be prefabricated as a unit, so that, basically, when the seat is assembled, this unit only needs to be hung into the back rest frame. The same applies especially to the above-mentioned variant in which the turnbuckle and motor are arranged in a shared housing affixed to the back side of the pressure plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will now be explained in more detail by referring to the enclosed drawings: Shown are: 
         FIG. 1  a top front perspective view of a back rest framework of a vehicle seat assembly with a fitted lordosis support, 
         FIG. 2  a front view of the lordosis support of the seat assembly of  FIG. 1 , 
         FIG. 3  a side view of the lordosis support of  FIG. 2 , 
         FIG. 4  a detail view of a portion of the lordosis support of  FIG. 2  shown in perspective, 
         FIG. 5  a rear view of the lordosis support of  FIG. 2 , 
         FIG. 6  a front view of a second embodiment of a lordosis support, in which an adjustment is made using only one motor, 
         FIG. 7  a side view of the lordosis support of  FIG. 6 , 
         FIG. 8  a front view of a third embodiment of a lordosis support, in which fans are arranged in the supporting plate and the pressure plate, 
         FIG. 9  a front view of a fourth embodiment of a lordosis support, in which the pressure plate and the supporting plate are connected as a single piece, 
         FIG. 10  a front view of a fifth embodiment of a lordosis support, in which fans are arranged in the pressure plate and in the supporting plate, 
         FIG. 11  a front view of a sixth embodiment of a lordosis support in which an adjustment is made using a counterrotating spindle drive, 
         FIG. 12  a perspective view of a detail of the lordosis support  FIG. 11   
     
    
    
     DETAILED DESCRIPTION 
     Detailed reference will now be made to the drawings in which examples embodying aspects of the present invention are shown. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar elements in the drawings and description have been used to refer to like or similar parts of the embodiments. 
     The drawings and description provide a full and detailed written description of the invention, and of the manner and process of making it and using it, so as to enable one skilled in the art to make and use it, as well as the best mode of carrying out the invention. However, the examples set forth in the drawings an description are provided by way of explanation and not by way of limitation. Thus, the present disclosure is directed to inventions including any modifications and variations of the following examples as come within the scope of the appended claims and their equivalents. 
       FIG. 1  shows the back rest framework  1  of a vehicle seat, which essentially comprises a closed frame made of plastic or metal. The frame is made of two side frame parts  3 , as well as an upper and a lower cross brace  4 ,  4   a . The lordosis support  6  itself essentially comprises two somewhat plate-like parts equipped with through holes  7 , namely a supporting plate  8  and a pressure plate  9 . The supporting plate  8  is connected to the pressure plate  9  by means of a hinged joint  10 . The supporting plate is always hung in a side frame part  3  with a helical extension spring  12 . Two holding elements  5   a ,  5   b , which are spaced apart vertically, are provided for adjustable holding of the pressure plate  9 . These always include two, somewhat screw-shaped, wound helical extension springs  13 ,  14 . The pressure plate  9  is affixed with these to the side frame parts  3 . Between the side edges of the pressure plate  9  and the side frame parts  3 , there is a space  29  through which the helical extension springs  13 ,  14  extend. Appendages  16 , which extend in the transverse direction of the seat (also called herein the Y-direction) and at least partially cover the helical extension springs  13 ,  14 , are arranged on the side edges of the pressure plate  9 . The appendages  16  are hinged in such a way on the pressure plate  9  that their angularity to the planar level of the pressure plate can be adjusted, which is accomplished by means of an attenuation point or a film hinge (not shown). On their back sides, the appendages  16  have a receptacle  17  that holds the helical extension springs  13 ,  14 , with a positive locking that works mainly in the longitudinal direction of the vehicle (the X-direction). This prevents the user from feeling the helical extension springs  13 ,  14  as uncomfortable pressure points or the springs from damaging the cushioning material. Furthermore, the embodiment being described also serves to affix the pressure plate  9  in the back rest frame, thus preventing shocks and vibrations. The receptacle  17  extends somewhat in the Y-direction and is bounded by two expandable spring tongues  18  for inserting a helical extension spring  13 ,  14 . 
     The spring end  19  of the helical extension springs  13 ,  14  pointing away from the pressure plate  9  basically extends rectilinearly away from the helical extension springs and is affixed with a clip  20  in an opening of a frame part  3 . In the relaxed position of the helical extension springs or in an inoperative position of the pressure plate, the spring ends  19  extend forward at a slant, relative to the Y-direction, thus encompassing an angle with the Y-direction that opens to the front, which can best be seen in  FIG. 3 . Here, the pressure plate  9  is in an inoperative position in which a horizontal clearance  11  existing at the side frame parts  3 , between the plate and the fixing points  30  (clips  20 ) of the spring ends  19 , is at its maximum. This is reduced, thereby moving the pressure plate  9  forward when the adjustment region  21  extending between the fixing points  30  shortens. In the embodiments shown in the drawings, this is accomplished by bringing the spring ends  19   a  that point to one another close together. For this purpose, they are connected by a connecting element that can be shortened using a motorized drive. 
     In the embodiments shown in  FIGS. 1 to 10 , the connecting element is a Bowden cable  22 , which connects two opposing helical extension springs  13  or  14  to each other. The casing  23  of the Bowden cable  22  is supported, on the one hand, by the housing  24  of an electric drive unit  25  arranged on a frame part  3  and, on the other hand, by a spring coil of a helical extension spring  13   a ,  14   a  ( FIG. 5 ) that is connected to the spring end  19 . The internal cable  26  of the Bowden cable  22  extends beyond the back side  27  of the pressure plate  9  up to the respectively opposing helical extension springs  13   b  or  14   b . On the back side  27  of the pressure plate, the internal cable  26  lies in at least one receptacle groove  28 . 
     When the helical extension springs are in the relaxed position, the pressure plate  9  is in a retracted position, wherein the horizontal clearance  11  ( FIG. 3 ) is at its maximum. The planar level  32  ( FIG. 3 ) of the pressure plate  9 , together with the planar level  33  of the supporting plate  8 , thus form an obtuse angle α opening to the front side of the back rest framework  1 . The aforementioned electrical drive units  25  are used to move the pressure plate  9  from this position. These units comprise an electric motor  35  and a gearbox  36 . The gearbox  36  contains a roller (not visible) for winding up the internal cable  26 . 
     In the embodiment with two drive units  25  shown in  FIGS. 1 to 5 , the following adjustment options are available. If, in the case of the upper holding element  5   a , the internal cable  26  is pulled into the casing  23  of the Bowden cable  22 , its area extending between the helical extension springs  13  is shortened. As a result of this, the upper area  37  of the pressure plate  9  is swiveled forward, according to arrow  38  in  FIG. 1 , wherein the lower holding element  5   b  forms a swivel axis. Due to the hinged joint  10  between the pressure plate  9  and the supporting plate  8 , the latter is swiveled slightly forward in the direction of the arrow  38 , wherein the helical springs  12  serve as the swivel axis. If the lower holding element  5   b  is shortened in the described manner, the lower area  39  of the pressure plate  9  moves analogously forward in the direction of the arrow  40 . The upper area  37  and the lower area  39  can also be moved forward in the direction of the arrows  38 ,  40  either simultaneously or time-delayed, in order, for example, to achieve a massage function by using a control device. In all of the aforementioned cases, the pressure plate  9  is returned to its position when the internal cable  26  is pulled out of the casing  23  by the relaxing helical extension springs  13  as the motor  35  on the gearbox  36  is rotated in the opposite direction. The pressure plate  9  is moved into its inoperative position by the weight of a seat user. In addition to the aforementioned movement options, the upper area  37 , like the lower area  39 , can be operated the opposite way, that is, in such a way that the lower area moves forward in the direction of the arrow  40  and the upper area moves backwards in the direction of the arrow  42  and vice versa. This can create pressure zones or pressure waves that move from the top down or from the bottom up. 
     In the embodiment shown in  FIGS. 6 ,  7 , there is only one drive unit  25 . Its gearbox  36   a  is designed in such a way that it can grasp the internal cables  26  of two Bowden cables  22  simultaneously and roll them up onto one spool using opposite winding directions. An adjustment is made starting from a middle position at which both helical extension spring pairs  13  or  14  are partially stretched. With this embodiment type, a simultaneous forward or backward movement of the upper area  37  and the lower area  39  is not possible. The aforementioned areas can, however, be alternately moved forward. 
     In  FIG. 8  an embodiment is shown in which fans are arranged in the supporting plate  8  and in the pressure plate  9 . With this design, air can be suctioned or pressed through a cushioned area arranged in front of the lordosis support, so that this area is cooled. 
     In  FIG. 9 , an embodiment is shown in which the supporting plate  8  is connected as one piece to the pressure plate  9 . As can be seen in  FIG. 10 , here there can also be fans  43  in the supporting plate  8  and in the pressure plate  9 . It is, of course, also conceivable that the fans  43  are present in only one pressure plate  9  or in only one supporting plate  8 . Instead of fans, other components, for example, switching devices, cushion fasteners, etc., can also be affixed to the pressure plate  9  and/or the supporting plate  8 . 
     In the section of the embodiment shown in  FIG. 11 , the ends  19   a  of the helical extension springs  13 ,  14  used for adjusting the pressure plate  9  are always moved toward one another using a turnbuckle  44 . A turnbuckle  44  has two ends  46 , each of which always has an eyelet  45 . A connector  47  that, on one of its ends, has a projection  48  that meshes into an eyelet  45  and, on the other end, is connected to a helical extension spring  13 ,  14 , always extends between the ends  46  and the springs  13 . As can be seen in  FIG. 12 , a turnbuckle basically comprises two spindles  49 , each of which has an end  46 , and two sheaths  50 . These always have an internal thread (not visible) that works together with the threads of the spindles  49 . The two sheaths  50  are affixed to each other with a torque-locked connection. One of the two sheaths  50  has a gear-wheel  51  with which both sheaths  50  can be rotated. The respective threads of the spindles  49  and sheaths  50  are inversely arranged, so that, during a rotation of the gear-wheel  51 , the ends  46  move either away from, or toward, each other. On the spindles  49 , there are flat areas  52  that serve to fix the rotation of the spindles  49 . In the embodiment in  FIG. 11 , each holding element  5   a ,  5   b  comprises a turnbuckle  44 . The two turnbuckles, along with the electric motors  53  assigned to them, are housed in a shared housing  54 , which is affixed to the back side of the pressure plate  9 . The housing  54  comprises two covers  55  that have recesses  56  for accommodating the electric motors  53  and the turnbuckles  44 . The electric motors  53  are always connected to the gear-wheel  51  of a turnbuckle  44  via a gearbox  57 , wherein the gearboxes  57  are likewise arranged in recesses  56  of the covers  55 . 
     While preferred embodiments have been shown and described, those skilled in the art will recognize that other changes and modifications may be made to the foregoing embodiments without departing from the scope and spirit of the invention. Specific shapes and dimensions of various elements can be altered for particular applications, and aspects of different embodiments can be combined to reach still further embodiments. It is intended that all such alterations are within the scope of the invention, as defined by the appended claims and their permissible equivalents.