Abstract:
A longitudinal adjusting device on a motor vehicle seat having a seat back adjustable relative to the seat part and forwardly foldable after releasing an arresting device, has movable rails on which the seat is fastened. The moveable rails can slide in guide rails attached to the vehicle. One movable rail has a locking device that releasably locks the moveable rail on the guide rail. The locking device has a positioning device for returning the seat to its previous longitudinal position. The positioning device has a positioning disc with locking teeth and an arresting lever with a toothed segment engaging the locking teeth. The arresting lever can be released from the locking teeth to allow rotation of the positioning disc during longitudinal adjustment of the seat. A spring-loaded winding drum is arranged coaxially to the positioning disc and allows the seat part to slide forward by a tension member attached to the seat part or the guide rail.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to a longitudinal adjusting device for the seat of a motor vehicle, especially two-door motor vehicles, the back of which seat can be tilted adjustably with respect to the seat part by means of adjusting hardware, and which, after the release of an arresting device, can be flipped forward, where the seat part is attached to movable rails which can slide along guide rails permanently attached to the vehicle, and where at least one movable rail has a locking device which can be disengaged from the guide rail, to which locking device a positioning device is assigned, which makes it possible for the seat to be returned to the original longitudinal position selected for it, which positioning device comprises a positioning disk with a set of external teeth, into which the toothed segment of an arresting lever engages, which lever is supported in a fixed position with respect to the movable rail but which can be moved out of the way if needed, where, coaxial to the positioning disk, a spring-loaded winding drum is mounted, by means of which the seat part can be shifted forward by the intermediate action of a tension member permanently attached to the vehicle floor or to the guide rail, the winding drum being provided with a stop for limiting the extent to which it can be rotated in the reverse direction by a counterstop on the positioning disk. 
     2. Description of the Related Art 
     A longitudinal adjusting device of the type described above can be derived from DE 196-47,447, in which the locking device can be released in two different ways so that the seat can be shifted longitudinally. First, by lifting a release handle in the forward area under the seat, the locking device attached to the movable rail can be released via a transverse lever from the position in which it is connected to the guide rail; that is, the locking catches of the locking device are lifted out of the row of teeth on the guide rail against the force of self-restoring springs. As this occurs, the end part of the release handle carries a connecting lever along with it in the release direction; this connecting lever lifts the toothed segment of an arresting lever out of the external teeth of a positioning disk. In this case, the previously selected terminal stop position used as a guide for returning the seat to the originally selected position is lost. So that the vehicle seat can be shifted without losing the position of the terminal stop, the connecting lever is detached from the release lever by way of an unlocking lever supported on the movable rail, so that the arresting lever remains undisturbed; as a result, the locking position of the positioning disk is pre-served. Nevertheless, the unlocking lever simultaneously presses the release handle against the transverse lever, so that this lever lifts the locking catches of the locking device out of the row of teeth on the guide rail. Thus, the previously selected stop position remains preserved in the memory module, while the seat part along with the forward-tipped back can be slid forward and back again to the previously selected stop. To assist the forward sliding movement of the seat, a previously mentioned winding drum is provided, which is spring-loaded in the direction of the forward sliding movement. This drum is connected by way of a tension member either to the floor of the vehicle in the forward area of the rail arrangement or to the forward end of the guide rail. The position of the stop used as a guide for returning the seat to its originally selected longitudinal position can be adjusted when the seat is slid backwards by allowing the rotation of the winding drum, which carries another stop, to move the stop of the positioning disk along until, upon completion of the rearward sliding movement of the seat, the locking device holds the movable rail in a fixed position on the guide rail. At this point, the pivoting of the release handle back to its original position also causes the positioning disk to be held by the arresting lever, so that the position which the stop on the positioning disk reached at that time is fixed. So that the winding drum can now be allowed to make several revolutions without the need to release the positioning disk, two check rings are inserted between the stop on the positioning disk and the stop on the winding drum; these rings in turn have their own stops, which can be carried along in succession by the winding drum. Thus, while the seat is being slid backwards, the stops on the check rings move the stop on the winding drum into a stop position with respect to the stop of the positioning disk, while the stop position of the positioning disk is being maintained. To ensure that the check rings function properly, they must be installed in the correct order one behind the other; otherwise, it is impossible for the originally selected position of the seat to be restored. In addition, if it desired to allow the seat to slide a long distance, the number of check rings arranged in a row must be increased. This requires a large amount of space in the width direction, and it also increases the cost. 
     SUMMARY OF THE INVENTION 
     The task of the invention is to improve a longitudinal adjusting device of the general type described above in such a way that, first, the above-cited disadvantages can be avoided, and, second, that the number of components, especially of the memory module, can be reduced. This task is accomplished by a link block, which is guided in a spiral connecting link and which makes it possible for the winding drum to rotate, being provided between the stop of the winding drum and the counter stop of the positioning disk. As a result, check rings, such as those used in the solution according to the state of the art described above, can be completely eliminated in the solution according to the invention. Another advantage is that, depending on the design of the spiral connecting link and the link block, it is possible, if needed, for the winding drum to execute more than the approximately two revolutions which can be achieved with the check rings known according to the state of the art, which means that the movable rails can be slid much farther along the guide rails. 
     A practical embodiment of the spiral connecting link and the link block can be achieved by designing the link block preferably as a ring segment, which has a guide rib which engages with the spiral connecting link. The connecting link takes the form of a groove recessed into the sidewall of the positioning disk. The spiral connecting link in this case is preferably designed so that it begins a short radial distance from the hub of the positioning disk and ends at the counterstop on the positioning disk, located radially just below the locking teeth; the pitch of the spiral connecting link is such that the radially outward directed component of the link block&#39;s motion can carry it underneath and past the counterstop of the positioning disk before the block makes its last revolution. 
     The link block can be given precise radial guidance as the positioning disk rotates by providing guide fingers on the link block, one projecting from each of the two end surfaces of the block, both pointing at the hub of the positioning disk. These guide fingers are arranged with respect to each other like a fork and project across the hub at a tangent to its outer circumference. It is obvious that the guide fingers must be long enough to remain in contact with the outside surface of the hub of the positioning disk even after the greatest possible radial distance between the link block and the hub of the positioning disk has been reached. 
     As previously mentioned, the counterstop is assigned to the positioning disk, whereas the stop is assigned to the winding drum. The stop on the winding drum can preferably be formed by the outsidewalls of an insertion pocket for a lead retainer seal of the tension member. 
     So that the winding drum can be rotated freely with respect to the positioning disk, the counterstop of the positioning disk projects axially only so far from its sidewall that the ribs and insertion pocket of the winding drum can be rotated freely past the counterstop. The axial length of the link block, furthermore, is greater than the axial length of the counterstop, because, when the link block is resting against the counterstop of the positioning disk, it must also form an abutment for the stop of the winding drum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention is shown in the drawing on the basis of an exemplary embodiment and is explained in greater detail below: 
     FIG. 1 shows a schematic diagram of a vehicle seat, seen from the side; 
     FIG. 2 shows a pair of rails of a vehicle seat arranged along one of the long sides of a seat provided with the longitudinal adjusting device, in a side view looking from inside the seat; 
     FIG. 3 shows a plan view of the pair of rails seen in FIG. 1 with the longitudinal seat adjusting device; 
     FIGS. 4 a - 4   c  show the rear area of the manually actuated release handle in three different positions. The position according to FIG. 4 a  shows the rest position; the position according to FIG. 4 b  shows how the locking device is released when the back of the seat is pivoted forward; and FIG. 4 c  shows how the locking device and the positioning device are released by the pivoting of the release handle; 
     FIG. 5 shows the positioning device in a longitudinal cross section along line V—V of FIG. 4 a;    
     FIG. 6 shows the positioning device seen in FIG. 5 in a cross section along line VI—VI of FIG. 5; 
     FIG. 7 shows the positioning device seen in FIG. 5 in a cross section along line VII—VII of FIG. 5; 
     FIG. 8 shows the locking device and the pair of rails in a cross section along line VIII—VIII of FIG. 2; and 
     FIG. 9 shows the longitudinal adjusting device comprising a positioning device together with a pair of rails in a perspective view looking toward the inside of the pair of rails. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The vehicle seat shown schematically in FIG. 1 consists of a seat part  10  and a seat back  11 , which is attached to the seat part by a hinge mechanism (not shown), which allows the angle of the back to be adjusted. The back can also be flipped forward with respect to seat part  10  around a pivot point  14  by pulling on a handle  13  connected to an arresting device  12 . Each of the two longitudinal sides of seat part  10  are connected along the bottom to a movable rail  15 , which engages in a guide rail  16 , both guide rails being attached permanently to the floor of the vehicle. Movable rail  15 , as can be seen especially in FIG. 8, is supported on guide rail  16  by rolling elements  17 ,  18  to allow freedom of longitudinal movement. On its incurved bottom, guide rail  16  has a longitudinal row of openings (not labeled separately), spaced a certain distance apart, which form a row of teeth. Into these openings, at least one of several locking catches  20  engages, these catches being components of a locking device  19 , mounted in a fixed position on movable rail  15 . The catches can be disengaged against the action of springs by a transverse lever  21 , also mounted on movable rail  15 ; to accomplish this, a release handle  22 , also in a fixed position on movable rail  15 , is actuated. Locking device  19  of the longitudinal seat adjusting device, however, can also be released by handle  13  on seat back  11  together with arresting device  12  of the seat back, in that an unlocking lever  24  is actuated by way of a Bowden cable  23 . This unlocking lever acts by way of an angled section  25  on release handle  22  in the unlocking direction and thus also actuates transverse lever  21  in such a way as to disengage locking catches  20  from the row of teeth in guide rail  16 . The unlocking lever is supported by a pivot  26  on a mounting plate  27 , which is attached in turn to movable rail  15 . A housing  28 , consisting of a lower housing part  29  and an upper housing part  30 , which holds positioning device  31  and its winding drum  32 , designed as a rotating element, is also attached to this mounting plate  27 . 
     Can-shaped upper housing part  30 , which can be seen in FIG. 5, is connected by way of clip projections  33  along the edges, which can also be seen in FIGS. 4 a - 4   c , to disk-shaped lower housing part  29 , this lower housing part  29  being permanently connected in a manner not shown to mounting plate  27  attached to movable rail  15 . An inward-projecting axle  34  is provided in the center of cup-like upper housing part  30 . A positioning disk  35  is supported with freedom of rotation on this axle  34 ; a set of locking teeth  36  extends around the entire outside circumference of the disk. On the side facing disk-shaped lower housing part  29 , positioning disk  35  has a recess, in which a spiral spring  37 , functioning as a torsion spring, is held. The inner, angled, end of this spring engages in a recess  38  in axle  34 , whereas the outer end of the spring is held in a manner not shown in detail in the circumferential area of the recess in positioning disk  35 . 
     Together with positioning disk  35 , the previously mentioned winding drum  32  is also supported on axle  34  so that it can rotate independently of the positioning disk. On the side facing away from positioning disk  35 , winding drum  32  has a recess  39 , which also holds a spiral spring  40 , which functions as a torsion spring. In a manner known in itself, the inner end of this spring is attached to axle  34 , whereas the outer end is attached to the outside lateral surface of winding drum  32 . The outside lateral surface of winding drum  32  has a section  41  of reduced diameter, which forms the holding space for a tension member  42 , which is attached to the winding drum and which can be in the form of a belt, for example. Underneath reduced-diameter section  41 , there is an insertion pocket  43 , oriented toward the center of winding drum  32 , in which a lead retainer seal  44 , permanently attached to one end of tension member  42 , fits. Each of the two outsidewalls of insertion pocket  43  extending in the axial direction forms a stop  45 , the purpose of which will be described later. In addition to the walls of insertion pocket  43 , which serve to increase the rigidity between the outside lateral surface and the hub of winding drum  32  and also form stops  45 , ribs  46  are also provided between the hub and the outside lateral surface of winding drum  32 . At the free end of tension member  42 , a lock-in-position piece  47  is provided, by means of which tension member  42  is attached to guide rail  16 , mounted in a fixed position on the floor. 
     A hub  49  projects from sidewall  48  of positioning disk  35 ; this hub points toward winding drum  32  and surrounds axle  34 . A short radial distance away from this hub  49 , a spiral connecting link  50  begins, and it ends at a counterstop  51 , which projects from sidewall  48  of positioning disk  35  just below locking teeth  36 . This counterstop  51  does not project far enough in the axial direction from sidewall  48  of positioning disk  35  to prevent either the radially oriented boundary walls of insertion pocket  43  or ribs  46  of winding drum  32  from rotating freely past counterstop  51 . Spiral connecting link  50  is formed by a groove recessed into sidewall  48  of positioning disk  35 . A guide rib  53  of a link block  52  engages in the groove which forms spiral connecting link  50 . Link block  52 , designed as a ring segment, forms an intermediate member between the associated stop  45  of winding drum  32  and counterstop  51  of positioning disk  35 . The axial dimension of the link block is selected so that it can come to rest, first, against the associated stop  45  of the winding drum and, second, against counterstop  51  of positioning disk  35 . To provide guidance, a guide finger  55  projects out from each end  54  of link block  52 . These guide fingers  55  are arranged to form a fork, and even in the most extreme radial position, they remain tangent to hub  49  of positioning disk  35  on both sides. 
     Upper housing part  30  has on its circumferential area, adjacent to disk-shaped lower housing part  29 , a cut-out section  56 , through which toothed segment  58  of an arm of disengagable arresting lever  57  can pass, so that it can engage with locking teeth  36  of positioning disk  35 . This arresting lever  57  is able to pivot around a pivot  59  on mounting plate  27 , and its toothed segment is held in engagement with locking teeth  36  of positioning disk  35  by a locking spring  60 , attached to an arm projecting from housing  28 . Now, in the same way as previously described in accordance with the state of the art, it would be possible for a connecting lever to be connected to arresting lever  57 , and this connecting lever could have a catch which would engage in a releasable manner in the tube at the end of the release handle. In the present embodiment, however, a downward-pointing fork lever  62  is nonrotatably attached to the same hub  61  as arresting lever  57 , but offset in the axial direction. A plunger  64  of a sleeve  63  extends into the open space between the sidepieces of fork lever  62 . The end of the plunger has a transverse head  72  projecting out toward both sides, and the sleeve is attached to the terminal area of release handle  22  in such a way that it is free to move in the longitudinal direction but is not free to rotate. The terminal area of release handle  22  begins behind transverse tube  65 , which is permanently connected to release handle  22  by welding, for example. As a result of this tube, release handle  22  is pivotably supported in bearing brackets  66  permanently attached to the rails. One end of a compression spring  67 , which surrounds release handle  22 , is braced against transverse tube  65 ; the other end of the spring acts on sleeve  63 . Sleeve  63 , which contains axially guided plunger  64 , has a laterally projecting pin  68 , which, as a result of the action of compression spring  67 , is held against an adjusting finger  69  of unlocking lever  24 . The inside surfaces of the sidepieces of fork lever  62  have radial cam sidepieces  70 , with which plunger  64  can come into contact when the rear part of release handle  22  is pivoted downward. 
     While seat part  10  is being held in the desired position, release handle  22 , unlocking lever  24 , and arresting lever  57  with its fork lever  62  are in the position shown in FIG. 4 a . When now the longitudinal position of the seat part of the seat is to be adjusted to a new position, handle lever  22  is pulled upward, so that its rear area pivots downward. During this pivoting movement, handle lever  22  presses transverse lever  21  (FIG.  8 ), so that the locking catches  20  of the locking device are lifted out of the row of teeth in guide rail  16 ; it thus becomes possible to slide movable rails  15 , to which the seat is attached, in the one or the other longitudinal direction of the vehicle. Simultaneously, however, when the rear part of handle lever  22  pivots downward, transverse head  72  of plunger  64  in sleeve  63  arrives at radial cam surfaces  70  and thus presses fork lever  62  forward. This lever therefore pivots around pivot  59  in the clockwise direction, and as a result toothed segment  58  is lifted out of the locking teeth of positioning disk  35 . This actuating position is shown in FIG. 4 c . It must also be pointed out that, as a result of a circular path  71  on adjusting finger  69  of unlocking lever  24 , which path curves around the center point of transverse tube  65 , sleeve  63  and thus also its plunger  64  retain their positions with respect to the terminal area of release handle  22 . This is so because no change has been made to the position of seat back  11 , and therefore unlocking lever  24  has not been actuated; it thus remains in the position shown in FIGS. 4 a  and  4   b . When now, in the actuating position shown in FIG. 4 c , the seat is slid forward or back, tension member  42  is paid out or rolled up on winding drum  32 . As a result, the cooperation of stop  45  on the drum, link block  52  resting against it, and counterstop  51  causes positioning disk  35  to rotate along with the drum, which it is free to do because arresting lever  57  has been swung out of position. As soon as the desired longitudinal position of the seat has been reached and release handle  22  has been let go, the handle swings back to its original position as shown in FIG. 4 a  under the force of the spring-loaded locking catches acting in the locking direction. At the same time, arresting lever  57  is swung back by locking spring  60  into its locking position as shown in FIGS. 4 a  and FIG. 6, where it holds positioning disk  35  in a fixed position. 
     When now seat back  11  is flipped forward and the seat is pushed forward out of this selected longitudinal seat position to allow more convenient access to the rear seat, the act of flipping back  11  forward has the effect of pulling on Bowden cable  23 . As a result, unlocking lever  24  is pivoted in the clockwise direction around pivot  26 , so that, on the one hand, bent section  25  of the lever presses the rear part of release handle  22  down. As this is happening, pin  68  on sleeve  63  follows adjusting finger  69  as the finger pivots forward in the clockwise direction under the force of compression spring  67 , with the result that transverse head  72  of plunger  64 , occupying the gap inside fork lever  62 , arrives in the free space between fork lever  62  and housing  28 , so that, when the rear part of release handle  22  is pushed down by bent section  25  for the purpose of pressing transverse lever  21  down, transverse head  72  of plunger  64  cannot come in contact with radial cams  70 . Arresting lever  57  therefore remains in the position in which its toothed segment  58  is engaged with locking teeth  36  of positioning disk  35 . The start of this actuating process is shown in FIG. 4 b . When transverse lever  21  is pressed down, however, it is possible, as a result of the sliding of locking catches  20  out of the row of teeth of the guide rail, for the seat to be pushed forward. During this sliding movement of the seat, link block  52  can be moved away from counterstop  51  of positioning disk  35 , because this stop, carried along in spiral connecting link  50  by stop  45 , is able to yield. When now the vehicle seat, which has had its back flipped forward and been pushed forward, is returned to its original position, winding drum  32  rotates against the action of spiral spring  40 , as a result of which link block  52  is carried along again by stop  45  until link block  52  comes to rest against the unchanged counterstop  51  of positioning disk  35 . At this point the originally selected longitudinal position of the seat is reached again. 
     As previously mentioned, the embodiment of the object of the invention illustrated and described above presents only an example, to which the invention is in no way limited. On the contrary, additional designs and embodiments of the object of the invention are also possible. All of the features shown in the drawing and mentioned in the description, furthermore, are essential to the invention, even if they are not explicitly stated in the claims. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 LIST OF REFERENCE NUMBERS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 seat part 
                 35 
                 positioning disk 
               
               
                   
                 11 
                 seat back 
                 36 
                 locking teeth 
               
               
                   
                 12 
                 arresting device 
                 37 
                 spiral spring 
               
               
                   
                 13 
                 handle 
                 38 
                 recess 
               
               
                   
                 14 
                 pivot point 
                 39 
                 cutout 
               
               
                   
                 15 
                 movable rail 
                 40 
                 spiral spring 
               
               
                   
                 16 
                 guide rail 
                 41 
                 area of reduced diameter 
               
               
                   
                 17 
                 rolling element 
                 42 
                 tension member 
               
               
                   
                 18 
                 rolling element 
                 43 
                 insertion pocket 
               
               
                   
                 19 
                 locking device 
                 44 
                 lead retainer 
               
               
                   
                 20 
                 locking catch 
                 45 
                 stop 
               
               
                   
                 21 
                 transverse lever 
                 46 
                 rib 
               
               
                   
                 22 
                 release handle 
                 47 
                 lock-in-position 
               
               
                   
                 23 
                 Bowden cable 
                 48 
                 sidewall 
               
               
                   
                 24 
                 unlocking lever 
                 49 
                 hub of 35 
               
               
                   
                 25 
                 bent section 
                 50 
                 spiral connecting link 
               
               
                   
                 26 
                 pivot 
                 51 
                 counterstop 
               
               
                   
                 27 
                 mounting plate 
                 52 
                 link block 
               
               
                   
                 28 
                 housing 
                 53 
                 guide rib 
               
               
                   
                 29 
                 lower housing part 
                 54 
                 end surface of 52 
               
               
                   
                 30 
                 upper housing part 
                 55 
                 guide finger 
               
               
                   
                 31 
                 positioning device 
                 56 
                 cut-out section 
               
               
                   
                 32 
                 winding drum 
                 57 
                 arresting lever 
               
               
                   
                 33 
                 clip projection 
                 58 
                 toothed segment 
               
               
                   
                 34 
                 axle 
                 59 
                 pivot 
               
               
                   
                   
                   
                 60 
                 locking spring 
               
               
                   
                   
                   
                 61 
                 hub of 57 and 62 
               
               
                   
                   
                   
                 62 
                 fork lever 
               
               
                   
                   
                   
                 63 
                 sleeve 
               
               
                   
                   
                   
                 64 
                 plunger 
               
               
                   
                   
                   
                 65 
                 transverse tube 
               
               
                   
                   
                   
                 66 
                 bearing bracket 
               
               
                   
                   
                   
                 67 
                 compression spring 
               
               
                   
                   
                   
                 68 
                 pin on 63 
               
               
                   
                   
                   
                 69 
                 adjusting finger 
               
               
                   
                   
                   
                 70 
                 radial cam surface 
               
               
                   
                   
                   
                 71 
                 circular path 
               
               
                   
                   
                   
                 72 
                 transverse head on 64