Abstract:
In a vehicle seat, in particular an automobile seat, with a height adjuster ( 9 ) for adjusting the height of a seat frame of the vehicle seat relative to the vehicle structure, a locking device ( 13, 23, 36, 38 ) is provided with a crash stop ( 31, 33, 36, 38 ), which makes available an alternative force transmission between the seat frame and the vehicle structure in the event of a crash.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This is a continuation of International Application No. PCT/EP00/10692, filed Oct. 31, 2000, and designating the U.S. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a vehicle seat, in particular an automobile seat, with a height adjuster for adjusting the height of a seat frame of the vehicle seat relative to the vehicle structure.  
           [0003]    In known vehicle seats of the above described kind, forces occurring in the event of a crash are transmitted from the seat frame, via the height adjuster, to the vehicle structure. In particular in the case of height adjusters that are actuatable by a motor, this disadvantageously stresses their drive, which is normally located between the seat frame and a movable element of the height adjuster.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with one aspect of the present invention, a vehicle seat is provided that performs advantageously in the event of a crash. In accordance with this aspect, the vehicle seat includes a seat frame mounted to a height adjuster. The height adjuster is for being connected between the seat frame and a vehicle structure, and adjusting the height of the seat frame relative to the vehicle structure. Further according to this aspect, a locking device is mounted to the vehicle seat for securing the height adjuster in a normal position during a normal condition, and for releasing the height adjuster in response to a crash in which the vehicle seat experiences at least a predetermined load. The locking device is provided with at least one crash stop that is engaged in response to the releasing of the locking device to establish an alternative force transmission path between the seat frame and the vehicle structure.  
           [0005]    As a result of providing a locking device with a crash stop, which makes available an alternative force transmission between the seat frame and the vehicle structure in the event of a crash, it is possible to transmit the crash forces from the seat frame, for example, directly into the seat rails and, thus, into the vehicle floor as a part of the vehicle structure. This relieves a drive for the height adjuster, which is operative between the seat frame and the height adjuster, and protects the drive against destruction. The term “seat frame” is understood to include other kinds of seat cushion supports and seat back supports. Because the locking device is designed to transmit a force in the event of a crash, the crash stop differs from simple, supplementary locking devices, which solely function to prevent an opening of the respective main locking devices.  
           [0006]    Preferably, the locking device is designed and constructed such that the crash stop responds irrespective of the adjusted height of the vehicle seat, namely each time about equally fast. It is preferred to provide two crash stops, which are operative in two different load directions and, thus, are in some ways not dependent on the type of load, i.e., they are operative both in a front end crash and in a rear end crash, but remain deactivated in the case of working loads and abusive loads. Preferably, activation occurs when a limit load is exceeded, in that, for example, the respective crash stop engages.  
           [0007]    Preferably, the crash stop is activated by a change in geometry within the height adjuster. If the height adjuster is designed and constructed as a coupler mechanism, a preferably elastic and therefore reversible deformation of the height adjuster will be able to occur within a four-bar linkage, on the hump side or door sill side, or between the two four-bar linkages. Examples for reversible crash stop activations are spring elements or a force limit locking device with a reset element. The force needed for deforming the height adjuster corresponds to the aforesaid limit force.  
           [0008]    In a preferred embodiment with a limit force locking device for activating the crash stop, a movably supported, spring-loaded locking pawl secures a bearing pin of a rocking arm of the height adjuster in the normal condition of the locking device. In the event of a crash, upon exceeding the limit force, the stop pawl releases the bearing pin for displacement in a guideway. This causes the geometry of the height adjuster to change, which then activates the crash stop. The spring force, which embodies the response threshold of the limit force locking device, and the arrangement of the guideway depend on the realization of the height adjuster kinematics and the occurring crash loads. It is necessary that the limit force locking device be capable of clearly disengaging and the crash stop of engaging over the entire height adjustment range and for each case of crash (front end crash and rear end crash).  
           [0009]    In a further preferred embodiment, the load transmitting crash stop is located between the height adjuster and the seat frame. In this instance, at least one movably supported toothed pawl is located either on the height adjuster or on the seat frame, and an associated toothed element is provided respectively on the other part, with the toothed pawl and toothed element engaging each other in the event of a crash. It is preferred to provide for the front end crash and the rear end crash respectively one toothed pawl and respectively one associated toothed element. Preferably, the two thus-formed gear tooth systems do not mutually exert on each other any expelling forces in the event of a crash. The subdivision into two separate, load-direction dependent crash stops has the advantage that it is possible to realize by nesting a load-level-adapted dimensioning and an axial securement of the crash stops being engaged.  
           [0010]    In a particularly preferred embodiment, the limit force locking device for the activation and the crash stops for the load transmission are parts of a common locking device, for example, in that the locking pawl and the toothed pawls are provided on a common, movably supported lever. This simplifies manufacture of the locking device and makes it more cost favorable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    In the following, the invention is described in greater detail with reference to an embodiment illustrated in the drawings, in which:  
         [0012]    [0012]FIG. 1 is a partial view of the right outer side of the embodiment in the region of a rear rocker arm without showing the seat frame;  
         [0013]    [0013]FIG. 2 is a partial view of the associated inner side in a normal condition without showing the rear rocker arm and seat frame;  
         [0014]    [0014]FIG. 3 is a schematically illustrated right side view of the embodiment;  
         [0015]    [0015]FIG. 4 is a view corresponding to FIG. 2 showing the rear rocker arm in the case of a front end crash;  
         [0016]    [0016]FIG. 5 is an enlarged view of the region V in FIG. 4; and  
         [0017]    [0017]FIG. 6 is an enlarged view corresponding to FIG. of the outward directed side of the associated region. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    A vehicle seat  1 , which is designed and constructed as the driver seat of an automobile, includes as a longitudinal adjuster, on each of its two sides, an upper rail  3 , which extends for displacement in the longitudinal direction of the vehicle in a lower rail  5  that is made integral with the vehicle structure. To each upper rail  3 , front and rear rocker arms  7  and  9  serving as height adjusters, are connected with a lower end. With their upper end, the rocker arms  7  and  9  are each connected to a seat frame  10 , which supports a seat cushion and a seat back of vehicle seat  1 . For the sake of clarity, the following describes the right side of the vehicle seat on the side of the hump. The left side of the vehicle seat on the side of the door sill is constructed in a corresponding way.  
         [0019]    To connect the rear rocker arm  9  to upper rail  3 , the upper rail  3  includes an upwardly projecting adapter  11  in the form of a bracket. A horizontally arranged bearing pin  13  is supported for rotation in adapter  11 . In a normal condition, the lower bearing pin  13  is arranged approximately in the center of a slotted guideway  15  of rear rocker arm  9 , and secured to the rear rocker arm  9  by means of a limit force locking device, as will be described further below. By means of an upper bearing pin  19 , which is located, depending on the adjusted height, more or less above and behind lower bearing pin  13 , when viewed in the travel direction, the rear rocker arm  9  is jointed to seat frame  10 .  
         [0020]    Somewhat above and in front of lower bearing pin  13 , when viewed in the travel direction, the rear rocker arm  9  mounts a pawl pin  21 , which is aligned parallel to the two bearing pins  13  and  19 . On the outward directed side of rear rocker arm  9 , the pawl pin  21  pivotably mounts a pawl lever  23 . The lower arm of pawl lever  23  supports a stop pawl  25 , which engages a receptacle  13 ′ that is provided in an annular flange of lower bearing pin  13 . A lock spring  27  is wound with its one end about pawl pin  21 , and engages with its other end pawl lever  23  such that stop pawl  25  is pushed into receptacle  13 ′ of lower bearing pin  13 . Up to a certain limit load, which is not exceeded in the case of working and abusive loads, the limit force locking device is locked in force-locking engagement, i.e., the force component acting in the direction of guideway  15 , which exerts an expelling force on stop pawl  23 , is compensated by static friction and by the force of lock spring  27 . Therefore, the lower bearing pin  13  is not rotatable relative to rear rocker arm  9 , and stationarily arranged within guideway  15 , so that this swivel joint causes rear rocker arm  9  to pivot relative to upper rail  3 , while entraining lower bearing pin  13 .  
         [0021]    The upper arm of pawl lever  23  mounts a first and a second toothed pawl  31  and  33 . The first toothed pawl  31  is made integral with pawl lever  23 , whereas the second toothed pawl  33  consists of a small metal piece mounted to the outer side of pawl lever  23 . The sawtooth-shaped teeth of the two toothed pawls  31  and  33  point approximately in the direction of upper bearing pin  19 . However, the teeth of the first toothed pawl  31  are slightly downward oriented, whereas the teeth of the second toothed pawl have a slightly upward orientation.  
         [0022]    At a small distance from these two toothed pawls  31  and  33 , the seat frame  10  includes a first and a second toothed segment  36  and  38 , which are arranged flat side by side. Their center of curvature is formed by upper bearing pin  19 , and their sawtooth-shaped teeth direct radially outward toward the two toothed pawls  31  and  33 . The teeth of first toothed segment  36  are directed slightly upward, whereas the teeth of the second toothed segment  38  have a slightly downward orientation. When the vehicle seat  1  is in its lowest position, the two toothed pawls  31  and  33  are oriented toward the upper end of the two toothed segments  36  and  38 . However, when the vehicle seat  1  is in its highest position, the two toothed pawls  31  and  33  are oriented toward the lower end of the two frame-integrated toothed segments  36  and  38 . FIGS. 1 and 2 show an intermediate position.  
         [0023]    In the event of a front end crash, the superstructure of vehicle seat  1  with seat frame  10 , the additional parts of vehicle seat  1  mounted thereon, and the user are accelerated forward relative to the substructure of vehicle seat  1  with rails  3  and  5 . Initially, the occurring forces are transmitted via rocker arms  7  and  9  to upper rail  3 , and further, via lower rail  5 , into the vehicle structure. In this process, the force acting upon rear rocker arm  9  exceeds the limit load of the limit force locking device, which is dependent on the force of lock spring  27  and the wedge angle of stop pawl  25 , i.e., stop pawl  25  is pushed out of receptacle  13 ′. The rear rocker arm  9  with its guideway  15  moves downward relative to lower bearing pin  13 , so that the lower bearing pin  13  comes into contact with the upper end of guideway  15 , thereby changing the geometry of the height adjuster. As a result of pushing out stop pawl  25 , the pawl lever  23  pivots about pawl pin  21 .  
         [0024]    This causes the first toothed pawl  31  to engage the first toothed segment  36 , as shown in FIG. 4, and to form a crash stop. As a result of the curved shape of first toothed segment  36  with an approximately constant distance of toothed pawl  31  in the starting position, this activation of the crash stop (and the duration of the response) do not depend on the height of vehicle seat  1 . The forces exerted by seat frame  10  are transmitted, on the one hand via upper bearing pin  19 , and on the other hand via first toothed segment  36 , first toothed pawl  31  of pawl lever  23 , and pawl pin  21 , to rear rocker arm  9 , and from same via lower bearing pin  13  to adapter  11  of upper rail  3 . This relieves the drive of the height adjuster that is operative between the rear rocker arm  9  and seat frame  10 .  
         [0025]    In the event of a rear end crash, the substructure of vehicle seat  1  is accordingly accelerated forward relative to the superstructure. The limit load of the limit force locking device is likewise exceeded. In so doing, the lower bearing pin  13  is released, and it comes into contact with the lower end of guideway  15 , thereby changing the geometry of the height adjuster. The pawl lever  23  pivots likewise. In so doing, the second toothed pawl  33  comes to engage now second toothed segment  38 , forms a further crash stop, and transmits a portion of the occurring forces. With respect to the angle relationships between the teeth, the crash stops are designed such that in the case of a rear end crash, the first (front end crash) gear tooth system  31  and  36  exerts no expelling forces on the second (rear end crash) gear tooth system  33  and  38 , and vice versa. The situation in the case of a front end crash is shown in FIGS. 5 and 6.