Abstract:
A motor vehicle seat includes at least one adjusting device, by means of which the position of a seat part can be adjusted against its weight and/or against the weight of a vehicle occupant sitting on the seat, and at least one spring element, which acts under preload on a kinematic chain of at least one adjusting device in order to reduce the backlash thereof, the kinematic chain transmitting the adjusting force. The spring element is arranged such that, on an adjustment of the seat part against the weight, the spring element is released, in order to supply the kinematic chain with spring energy, and tensioned on an adjustment of the seat part in the weight direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
         [0001]    This application is a National Phase Patent Application of International Application Number PCT/DE02/03410, filed on Sep. 9, 2002, which claims priority of German Patent Application Number 101 45 843.6, Filed on Sep. 10, 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    A motor vehicle seat is disclosed in DE 198 45 772 A1 having at least two adjusting devices for adjusting the seat and/or parts of the seat whereby the adjusting device has means for compensating for any possible backlash in the adjusting device. The means for compensating for the backlash comprise a pretensioned elastic element which is arranged so that the force generated by the elastic element acts on the gearing of at least two adjusting devices, the force generated preferably having components parallel to the direction of each adjusting movement produced by the individual adjusting devices. In this manner it is possible to compensate for any possible backlash in two or more adjusting devices with only one elastic element.  
           [0003]    According to the disclosure of DE 198 45 772 A1, it is also possible for a spring element to compensate the backlash of several adjusting devices in a motor vehicle seat.  
         SUMMARY OF THE INVENTION  
         [0004]    A motor vehicle seat according to the present invention comprises in one embodiment at least one adjusting device with which a part of the seat can be adjusted in position against its own weight and/or against the weight of an occupant of the seat. The seat also comprises at least a spring element to reduce backlash. The spring element is pretensioned on a kinematic chain of the at least one adjusting device wherein the kinematic chain transfers the adjusting force.  
           [0005]    The adjusting device may comprise a device for adjusting the seat height, or a device for adjusting the backrest rake of a vehicle seat. The kinematic chain serves to transfer the adjusting force from a drive of the relevant adjusting device to the seat part which is to be adjusted (which in exemplary embodiments include a vertically adjustable seat frame or an incline-adjustable seat back) and can be formed in one embodiment as a lever assembly.  
           [0006]    In one embodiment of the present invention, the spring element serving to compensate for the backlash is arranged so that during adjustment of the seat part, it relaxes against the weight so that spring energy is introduced into the kinematic chain. During adjustment of the seat part in the direction of the weight the spring element is tensioned.  
           [0007]    This arrangement of the spring element has the advantage that the spring element assists the adjusting movement opposite the loading direction while counteracting an adjusting movement of the seat part in the direction of the force of the weight. The spring element equalizes adjusting forces required for adjusting a seat part against the weight with those required for adjusting a seat part with the weight. In particular, the situation is avoided wherein the adjusting force required for adjusting a seat part against the weight is substantially larger than the adjusting force required for adjusting a seat part in the loading direction.  
           [0008]    In a preferred embodiment, the spring element exerts a force with a component in the loading direction on a force engagement point which is associated with the seat part which is to be adjusted. In alternative embodiments, the force engagement point may be located either on the seat part itself or on a component part which during actuating of the adjusting device can move together with the seat part. The force engagement point of the spring element which is to be associated with the seat part to be adjusted is arranged so that it is moved during displacement of the seat part opposite the loading direction so that the spring element is relaxed.  
           [0009]    This behaviour of the spring element which is initially contradictory can be reached with a spring element which serves to reduce the backlash of an adjusting device for the height of a seat part. The spring element is tensioned between its two force engagement points and inclined to the loading direction such that it relaxes when the seat part is lifted as a result of the superimposed longitudinal movement of the seat part in the seat longitudinal direction. The backlash which causes, during adjustment of the height, a longitudinal movement of the seat part in the seat longitudinal direction superimposed thereon (as is conventional in the case of seat height adjusting devices based on a parallelogram kinematic principle).  
           [0010]    With a spring element which serves to reduce the backlash of an adjusting device for the incline of a seat part mounted to pivot about an axis whereby the adjustable seat part forms in relation to the pivotal axis a first lever arm (as is usual in adjusting devices for the backrest incline), the force engagement point of the spring element associated with the seat part is arranged outside of the first lever arm on a second lever arm which is formed in one embodiment through a projection of the seat part.  
           [0011]    In one embodiment, the spring element can be formed as a tension spring the force engagement points or which move closer together when adjusting the corresponding seat part opposite the loading direction and move further apart when adjusting the seat part in the loading direction.  
           [0012]    In an alternative embodiment, the spring element is a compression spring arranged so that its force engagement points move away from each other during adjustment of the corresponding seat part opposite the loading direction and move closer together during adjustment in the loading direction.  
           [0013]    The spring element can be of different spring types adapting to the conditions of the relevant adjusting device. In various embodiments the spring element is a linear spring, a torsion spring or a coil spring.  
           [0014]    In a preferred embodiment of the invention, all members of the kinematic chain of the adjusting device lie between the force engagement points of the spring element so that the spring element causes a reduction in the play of the overall adjusting device.  
           [0015]    A force engagement point of the spring element preferably lies outside of the kinematic chain of the adjusting device, more particularly on a part which during actuation of the adjusting device does not changes its position relative to the vehicle body. In one embodiment, this part may be a part of the base group of the seat. In a further embodiment it may be the top rail of a rail longitudinal guide.  
           [0016]    The other force engagement point of the spring is provided on a part which during actuation of the adjusting device does change its position (together with the seat part which is to be adjusted), for example on a part of the kinematic chain of the adjusting device. The part which changes its position can thereby be moved throughout actuation of the adjusting device relative to the seat part. It is solely decisive that the corresponding part is moved along automatically during movement of the seat part which is to be adjusted.  
           [0017]    In one embodiment, the movable force engagement point is mounted on a pivotal lever arm or a gearing element of the kinematic chain.  
           [0018]    In an alternative embodiment of the invention, one force engagement point of the spring element is provided on the seat part which is to be adjusted and the other force engagement point of the spring element is provided on a link of the kinematic chain.  
           [0019]    In another alternative embodiment, a force engagement point of the spring element associated with the seat part which is to be adjusted is provided on an additional gearing element which is mounted outside of the kinematic chain of the seat adjusting device. This force engagement point acts on one element of the kinematic chain, preferably a gearing element. The phrase “mounted outside of the kinematic chain” means in this context that the additional gearing element interacts with the kinematic chain only as a result of the action of the spring element, and that the kinematic chain could also transfer fully functioning adjusting forces without the additional gearing element.  
           [0020]    The additional gearing element preferably acts under the pretensioning force of the spring element on the said element of the kinematic chain so as to assist movement of the element of the kinematic chain which leads to an adjustment of the seat part opposite the loading direction. Spring energy may then be fed into the kinematic chain. Conversely, in this case the additional gearing element counteracts an adjustment of the corresponding seat part in the loading direction as a result of the pretensioning force of the spring element.  
           [0021]    With this arrangement, the spring element can serve together with the additional gearing element to remove the backlash from the gearing elements of the adjusting devices by the additional gearing element acting on a gearing element of the kinematic chain. By removing the backlash, this additional gearing element is pressed against the gearing element of the kinematic chain.  
           [0022]    In one embodiment of the present invention, a gear wheel driven by the drive of the adjusting device engages a gearing element mounted in the kinematic chain whereby an additional toothed gearing element is provided the teeth of which coincide with the gearing element mounted in the kinematic chain. The gearing element mounted in the kinematic chain and the additional gearing element can thereby be formed in one embodiment as pivotally mounted toothed segments. The additional gearing element can be mounted to pivot freely on the axis of the gearing element mounted in the kinematic chain. The force engagement point of the spring element on the additional gearing element is spaced from this axis.  
           [0023]    It is understood that the use of an additional gearing element for removing the backlash from the gearing is independently possible for any type of gearing, more particularly for a toothed wheel gearing.  
           [0024]    Further features and advantages of the invention will now be explained with reference to the embodiments illustrated in the following drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    [0025]FIG. 1 is a diagrammatic view of a vertically adjustable vehicle seat with a spring element for reducing the backlash in the adjusting device for the seat height which engages with one end on the height adjustable seat part;  
         [0026]    [0026]FIG. 2 shows a modification of the embodiment of FIG. 1 in which the spring element engages with one end on an adjusting lever of the adjusting device for the seat height;  
         [0027]    [0027]FIG. 3 shows a further modification of the embodiment of FIG. 1 wherein the spring element engages by one end on an additional gearing element which does not serve for transferring adjusting forces on the seat part which is to be adjusted;  
         [0028]    [0028]FIG. 4 is an enlarged view of a detail of the assembly of FIG. 3;  
         [0029]    [0029]FIG. 5 shows a modification of the embodiment of FIG. 4;  
         [0030]    [0030]FIG. 6 depicts a diagrammatic view of an incline-adjustable seat back with a spring element for reducing the backlash in the adjusting device for the backrest rake;  
         [0031]    [0031]FIG. 7 shows a modification of the embodiment of FIG. 6 in which the spring element engages an additional gearing element which does not serve for transferring adjusting forces onto the backrest. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    [0032]FIG. 1 shows a side view of a seat frame  1  comprising a height-adjustable seat support  10  as well as a backrest  20  pivotally attached thereon.  
         [0033]    A known parallelogram kinematic system exists for adjusting the height of the seat support  10  in which a front adjustment lever  11  and a rear adjustment lever  12  are attached on each side of the support  10  to pivot about the axes  11   a  and  12   a , respectively. The adjustment levers  11  and  12  are each mounted at one end to pivot about the axes  11   b  and  12   b  respectively on a structural assembly on the vehicle floor side. In one embodiment, this structural assembly may comprise the top rail of a longitudinal rail guide. With an adjusting device of this kind, any change in the seat height h which is triggered by pivoting the adjustment levers  11  and  12  leads to a corresponding shift of the seat support  10  in the seat longitudinal direction L (corresponding to the vehicle longitudinal axis in a motor vehicle). In more precise terms, any increase in the seat height h leads to the seat support  10  shifting forwards and any reduction in the seat height h leads to the seat support  10  shifting back (in relation to the forward drive direction of the vehicle).  
         [0034]    In order to reduce the play in the adjustment device for the height of the seat support  10  and thus of the seat overall, a spring element  5  is provided comprising a linear tension spring fixed at one end at a first force engagement point  51  to a floor-side structural assembly of the vehicle (e.g. to the top rail of a longitudinal rail guide a) and at its other upper end at a second force engagement point  52  to the seat support  10 . The fixation point of the lower force engagement point  51  of the spring element  5  coincides with the lower bearing point of the front adjustment lever  11 . The two force engagement points  51  and  52  are arranged so that the spring element  5  runs in an inclined position from the bottom at the front upwards towards the back (in relation to the drive direction of a vehicle) between these two points  51  and  52 .  
         [0035]    The spring element  5  exerts a force forwards and downwards on the seat support  10  so that the spring force has a component in the loading direction G which acts on the seat support  10  or on a person located on the seat. As such, the seat support  10  is pretensioned by the spring element  5  in the direction of the vehicle floor in addition to being pretensioned in the loading direction G.  
         [0036]    As a result of the inclined diagonal arrangement of the spring element  5 , an increase in the seat height h by swivelling the adjustment levers  11  and  12  leads to the two force engagement points  51  and  52  of the spring element  5  moving closer together. Any increase in the seat height h is (as is already described above) accompanied by the seat support  10  moving forwards. As a result, the upper force engagement point  52  of the spring element  5  provided on the seat support  10  moves nearer in the seat longitudinal direction L to the lower force engagement point  51 , which is locally fixed. With a suitable arrangement of the spring element  5 , more particularly its force engagement points  51  and  52 , this leads to a net reduction in the distance between the two force engagement points  51  and  52  despite the increase in the distance between the two force engagement points  51  and  52  along the vertical vehicle axis z.  
         [0037]    This means that the spring element  5  in the form of a tension spring relaxes in the event of an increase in the seat height h by means of the associated adjusting device. This increase takes place against the load G, and releases spring energy (potential energy) to make the increase in the seat height easier and reduces the amount of force needed to be applied by the adjusting device in order to increase the seat height. The spring element  5  thus assists in raising the seat support  10  opposite the loading direction G, although it also pretensions the seat support  10  down in the direction of the load G.  
         [0038]    [0038]FIG. 2 shows a modification of the embodiment of FIG. 1 whereby in contrast, the upper force engagement point  52  of the spring element  5  does not engage directly on the seat support  10  but rather on a projection of the rear adjustment lever  13 . This rear adjustment lever  13  is attached by its upper end on the seat support to pivot about an axis  13   a  and by it lower end to a floor-side structural assembly of the vehicle to pivot about an axis  13   b . The upper force engagement point  52  of the spring element  5  thereby coincides with a point  13   c  of the rear adjustment lever  13  which, in the event of an increase in the seat height h relative to the seat support  10 , executes a movement with a component downwards towards the vehicle floor (i.e. against the upward pointing vertical vehicle axis z). This leads to an additional reduction in the distance between the two force engagement points  51  and  52  of the spring element  5 , and thus to an additional relaxation of the spring element  5 . The fixation of the spring element  5  and its force engagement point  52  associated with the seat support  10  on a component part (such as the adjustment lever  13 ) which in turn is moved during and together with the adjustment of the seat side part  10  (and in addition is moved towards the other force engagement point  51  of the spring element  5 ) is particularly advantageous in the case of vehicle seats which, during adjustment of the seat height, only execute a slight displacement in the seat longitudinal direction L.  
         [0039]    In the embodiments of FIGS. 3 and 4 the adjusting device for the seat height is shown having a drive device  3  as well as two adjustment levers  11  and  13 , of a similar embodiment to that shown in FIG. 2. The drive device  3  is associated with the rear adjustment lever  13  such that the front adjustment lever  11  only serves as a passive compensating lever.  
         [0040]    The drive device  3  has as a drive an actuating lever  30  (manual drive) with which a pinion  31 , rotatable about an axis  31   a , can be actuated. Teeth of the pinion  31  mesh in a longitudinal spline  33  of a toothed segment lever  32  which is pivotally mounted about an axis  32   a . The longitudinal spline  33  is formed in an elongated recess  32   b  of the toothed segment lever  32 . A coupling lever  14  is attached to a bearing site  34  of the toothed segment lever  32 . The coupling lever  14  transfers any movement introduced by the actuating lever  30  through the pinion  31  into the toothed segment lever  32  to the rear adjustment lever  13 . Depending on the actuating direction of the actuating lever  30 , the seat support  10  can be selectively raised or lowered. Manual adjustment devices of this kind for the seat height are known in the art; as such, further details will not be provided.  
         [0041]    An additional toothed segment lever  35  is mounted with its swivel axis  35   a  on the swivel axis  32   a  of the toothed segment lever  32 . This toothed segment lever  35  has a longitudinal spline  36  in an elongated recess  35   b  which coincides in geometry and design with the longitudinal spline  33  of the aforementioned toothed segment lever  32 .  
         [0042]    In contrast to the first mentioned toothed segment lever  32 , the additional toothed segment lever  35  forms no link in the kinematic chain transferring an adjusting force exerted by the actuating lever  30  through the gearing elements  31  and  32  to the seat side part  10 , the coupling lever  14  and the rear adjustment lever  13 .  
         [0043]    The additional toothed segment lever  35  has a bearing point  37  for fixing the upper end of a spring element  6  (provided in this exemplary embodiment by a linear tension spring) by its upper force engagement point  62 . The lower force engagement point  61  of the spring element  6  is fixed on a floor-side structural assembly of the vehicle. In one embodiment this assembly comprises the top rail of a seat longitudinal guide. The spring element  6  is mounted in the region of the rear adjustment lever  13  of the adjusting device for the seat height and serves to remove the backlash from this adjusting device.  
         [0044]    It can be seen from FIGS. 3 and 4 that the additional toothed segment lever  35  is tensioned by its teeth  36  through the action of the spring element  6  against the teeth of the pinion  31 . As such, at least one toothed element of the pinion  31  located in engagement with the teeth  33  of the toothed segment lever  32  mounted in the kinematic chain is pressed against a toothed flank of the teeth  33 . In this manner, the play is removed from the gearing  31  and the toothed segment lever  32  of the drive device  3 , and thus the adjusting device for the seat height. The spring  6  thus serves to remove the play from the gearing of the drive device  3 .  
         [0045]    To explain the function of this arrangement, it can be seen from a first arrow RF in FIG. 4 how the additional toothed segment lever  35  is stressed under the action of the spring element  36  in the opposite direction around the axis  35   a  from the first toothed segment lever  32  under the action of the load G about its identical swivel axis  32   a  (see corresponding arrow R B ).  
         [0046]    With a resting seat, torque is introduced through the additional toothed segment  35  by means of the spring element  6  into the seat support  10  through a brake device, mounted in a manner known to one skilled in the art between the gearing elements  31  and  32  and the drive lever  30 . If torque is applied on the drive side to the actuating lever  30  which leads to an increase in the seat height h (see arrow M in FIG. 3), then the torque exerted on the pinion  31  by the spring element  6  through the additional toothed segment lever  35  assists the corresponding adjusting movement of the pinion  31  and thus indirectly also the elements  32 ,  14  and  13  on the output side.  
         [0047]    The spring element  6  also serves to tension the support  10  in the direction of the vehicle floor in order to remove play from the entire adjusting device for the seat height. Furthermore with an increase in the seat height h, the two force engagement points  61  and  62  of the spring element  6  are moved towards each other so that the spring element relaxes and supports the corresponding adjustment movement. The spring element  6  is also made to support the corresponding adjustment movement through a diagonal inclined arrangement of the spring element  6  which is fixed by its upper force engagement point  62  on a component part (in one embodiment the additional toothed segment lever  35 ) which is connected to the seat support  10 . With an increase in the seat height h in the region of the bearing point  37  for the upper end of the spring  6 , the component part moves down so that the approach movement of the two force engagement points  61  and  62  towards each other is further assisted during an increase in the seat height h.  
         [0048]    [0048]FIG. 3 shows an alternative embodiment of a spring element  6 ′ which is fixed by a lower force engagement point  61 ′ on a floor side structural assembly of the vehicle and by its upper force engagement point  62 ′ on the previously described bearing point  37  of the additional toothed segment lever  35 . The spring element  6 ′ is mounted running along the vehicle longitudinal direction L and is only deflected in the region of its rear spring end by means of a deflection element  65 ′ so that this spring end is guided towards the upper force engagement point  62 ′. The upper force engagement point  62 ′ and the deflection element  65 ′ are arranged so that a straight connecting line (connecting path) extends between the two points  62 ′ and  65 ′ inclined to the longitudinal direction L of the vehicle from the bottom at the front up to the back.  
         [0049]    In order to achieve a particularly sustained tensioning of the seat support  10  for the purpose of reducing the play and assisting the adjusting movement opposite the loading direction G, spring elements  5  and  6  can be used at the same time arranged in the region of the front adjustment lever or the rear adjustment lever of the adjusting device for the seat height.  
         [0050]    [0050]FIG. 5 shows an alternative to the embodiments of FIGS. 3 and 4 whereby the spring element  6  is fixed by its one force engagement point  61  on the seat support  10  and by its other force engagement point  62  on the additional toothed segment lever  35 . In this embodiment, the spring element  6  serves only to remove the play from the gearing elements of the adjusting height for the seat height, but cannot remove the play from the adjusting device overall. One advantage of this embodiment is that there is no powerful counter effect on the seat overall whereby the assembly of the seat is easier due to the lack of tensioning of the seat.  
         [0051]    [0051]FIG. 6 shows diagrammatically a part of the backrest frame  20  of the seat frame  1  of FIG. 1, which is mounted pivotally about an axis  21  whereby the backrest frame  20  forms a first lever arm  20   a  in relation to the swivel axis  21  which supports the back of the vehicle occupant, as well as a second lever arm  20   b.    
         [0052]    A toothed segment  42  is provided in the region of the pivotal axis  21  on the backrest frame  20 . The toothed segment  42  has a toothed spline  43  which meshes with the spline of a pinion  41  which is rotatable about an axis  41   a . The pinion  41  is rotatable through an associated manual or remote-controlled drive and triggers swivel movement of the first lever arm  20   a  forwards or backwards depending on the direction of rotation. In an alternative embodiment, the associated drive is an electric drive.  
         [0053]    In the adjusting region in which the backrest frame  20  is located in a useful position in which the backrest frame  20  can support the back of a vehicle occupant located on the seat, the backrest is located either in a perpendicular position (parallel to the vertical vehicle axis z) or it is inclined backwards. Where the backrest is inclined backwards, the load G acting on the backrest frame  20  has the tendency to intensify the incline of the first lever arm  20   a  backwards. In addition, the force F Lehne  of an occupant located on the corresponding seat and leaning back against the backrest can still act in the same direction.  
         [0054]    As a result, any adjustment of the incline of the backrest which moves it from a rearwardly inclined useful position towards the vertical position takes place opposite the loading direction G. In order to assist such adjustment of the backrest, a spring element  7  is provided fastened by one lower force engagement point  71  (and thus not on a common component part which can pivot with the backrest frame  20 ) and by the upper force engagement point  72  on a projection  22  of the backrest frame  20  which forms a second lever arm  20   b . The projection  22  forming a second lever arm  20   b  is tensioned in the loading direction G through this spring element  7  with a defined force F Feder  so that the first lever arm  20   a  formed by the backrest frame  20  is biased opposite the loading direction G.  
         [0055]    At the same time the spring element  7 , like the corresponding spring elements  5  and  6  in the previous embodiments, serves to reduce the play in the adjusting device for the backrest inclination. This causes among other effects an interaction of the pinion  41  with the teeth  43  of the toothed segment lever  42  which is, as far as is possible, free of play.  
         [0056]    [0056]FIG. 7 shows a modification of the embodiment of FIG. 6 in which an additional toothed segment lever  45  is mounted to freely pivot about the pivotal axis  21  of the backrest. This toothed segment lever  45  has an external spline  46  which coincides in geometry and design with the teeth  43  provided on the toothed segment  42  of the backrest frame.  
         [0057]    Using its upper force engagement point  72 , the spring element  7  engages the additional toothed segment lever  45 . The teeth  46  of the toothed segment lever  45  exert a corresponding moment (which is produced from the pretensioning force of the spring element  7  and the distance of the force engagement point  72  from the pivotal axis  21  of the backrest) on at least one toothed flank of the drive pinion  41 . In this manner, the corresponding toothed element of the drive pinion  42  is made free of play and is pressed against the teeth  43  of the toothed segment lever  42  provided on the backrest frame  20 .  
         [0058]    Furthermore, the moment exerted by the teeth  46  of the additional toothed segment lever  45  assists in the rotational movement of the toothed pinion  41  in a direction which assists displacement of the backrest opposite the loading direction G, corresponding to an adjustment of the first lever arm of the backrest frame  20  in the direction of the substantially perpendicular position. The corresponding rotary direction R of the toothed pinion  41  is indicated by an arrow in FIG. 7. Therefore, the additional toothed segment lever  45  acts on the drive pinion  41  against the action of the load G which engages on the first lever arm  20   a  of the backrest frame  20 ; the toothed segment lever  45  also acts through its toothed segment lever  42  on the drive pinion  41 .