Abstract:
The device for the detachable connection of a vehicle seat with the vehicle floor with a rear fixing hook open in the travel direction and in which a fixing bolt on the vehicle floor can engage, and a front slide guide for supporting the vehicle seat on the front fixing bolt as well as a rotatably mounted claw-like locking lever biased by a spring force to lock the front fixing bolt in the slide guide wherein the rear fixing bolt is associated with a swivel mounted claw-like primary locking element biased by a spring force against the locking position, wherein the position of the primary locking element on reaching the locking position can likewise be locked by a secondary locking element, is characterized in that the front primary locking element and the rear secondary locking element are coupled together by a coupling element, preferably a coupling rod.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a device for the detachable connection of a vehicle seat that guarantees a secure locking and when necessary a simple unlocking of the vehicle seat. 
     From German Patent DE A1 44 04 935 a device is known for connecting a vehicle seat to a vehicle floor which uses for locking the seat to a bolt of the front bearing block a double-armed locking lever, and for locking with the bolt of the rear bearing block a hook which is open in the travel direction. The double-armed locking lever is held in the unlocked position by a spring in a stop wherein the free end of the one arm is associated with a stop fixed on the vehicle floor. After inserting the fixing point of the vehicle seat into the floor-side bearing blocks, the seat is pushed forwards to produce the keyed locking connection whereby the rear fixing bolt enters between the flanks of the rear fixing hook. At the same time the seat slides inclined down and forwards on a guide slide of a support plate which also supports the double-armed locking lever. This produces an engagement of the floor-side support with the one arm of the locking lever and its swivelling in the direction of the locking position. After reaching a certain swivel angle, the active direction of the spring on the locking element changes round so that this locking element is automatically drawn into the locking position. 
     The described device does indeed allow a single locking and unlocking of a vehicle seat but it does have the drawback however that the rear locking point is designed in the form of an open hook and cannot absorb forces against the travel direction. In the event of a rear impact crash the front locking point would have to divert the entire energy connected therewith. Furthermore it cannot be completely ruled out that the seat is locked in the front bearing block while the rear fastening hook does not enclose the fixing bolt but stands up on same. Such an unsecured seat gives rise to a considerable risk of accident and injury. 
     German Patent DE 44 08 696 C1 describes a device for connecting a longitudinal support of a vehicle seat with the vehicle structure whereby a fixing claw which is open to the back engages round a fixing bolt fixed on the body so that even crash forces produced at the rear can be absorbed. After the rear fixing area has been brought into positive engagement the front fixing claw can be lowered onto the associated fastening bolt and can be secured by means of a locking element. 
     A disadvantage here however is that a locking of the front seat area can also then take place when the rear fixing area rests on the fixing bolt on the bodywork side, i.e. when no rear locking exists. Such a faulty mounting can, during operation of the vehicle, more particularly with severe negative accelerations, lead to the seat folding forwards and thus to severe injury to the user. 
     From U.S. Pat. No. 5,282,662 a device is known for detachably connecting a vehicle seat to the vehicle floor. The device has two front and two rear slide guides. Fixing bolts are located in engagement with each engagement of the front and rear slide guide. The vehicle seat is fixed or locked on the fixing bolts by fixing hooks. Furthermore the known device has a rod which connects a support foot with a leg of the vehicle seat. In order to remove the vehicle seat it is folded into a vertical position whereby the rear slide guides (or legs of the seat) fold together as a result of their connection with the foot through the rod. 
     Even with this known device a locking of the front seat area can take place even if the rear fixing area is not properly locked. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to produce a device for detachably locking a vehicle seat to the floor of a motor vehicle which guarantees a simple and at the same time reliable locking and unlocking of the vehicle seat. 
     According to the invention the locking processes of the front and rear locking devices are connected together by a coupling element, for example a coupling rod wherein the force required for the swivel movements of the front locking element and the secondary locking element is applied by a common spring element. It can thereby be ensured that a locking of the seat with the front fixing bolt can only take place when the rear seat locking has been safely completed. 
     In order to achieve a still higher standard of safety the embodiment last described is completed by a blocking element which does not allow the release of the locking process at the front fixing bolt if the fixing bolt has still not reached the intended area of the slide guide of the front support plate. The likewise swivelling blocking element, biased by a spring prevents, through a support of the blocking element, its locking movement until the blocking element is forced by the fixing bolt against the spring force out of the covering area above the slide guide. 
     The additional use of a primary locking element whose position on reaching the locking state is locked by a secondary locking element secures the fixing bolt in the slide guide of the rear fixing hook which is open on one side. It is thereby prevented that the rear seat fastening can become inoperative, particularly following a rear impact crash wherein the floor group is temporarily deformed three-dimensionally or elastically. Through the enormous elastic tensions which thereby occur in the seat frame the seat would then be spun forwards whereby it swivels about the front fixing points. The risk of injury which occurs can thereby be considerable. 
     In a preferred embodiment of the invention the claw-like swivel-mounted primary locking element is biased by a spring element against the locking direction and is at first held by a secondary element in a position which engages over the entrance to the slide guide of the fixing hook. Thus, during assembly of the seat on the vehicle floor, the fixing hook first passes into the claw of the primary locking element and only then in sequence into the slide guide of the fixing hook. On reaching the locking position provided the secondary locking element locks the position of the primary locking element and thus also the position of the fixing bolt in the slide guide of the fixing hook. The secondary locking element is also preferably spring-loaded so that the locking process develops practically automatically and reliably. 
     A device is thus provided for detachably locking a vehicle seat to the vehicle floor which apart from a substantially increased security in the event of a rear impact crash and simple handling also has a high security against a possible faulty locking. Both in the front and in the rear area the locking can only take place when both fixing bolts have occupied the prescribed ideal position. The locking state can easily be established by checking the position of the easily accessible handle at the front locking element. 
     By means of this handle it is likewise possible to readily release the front and rear locking. After the handle has been drawn upwards the blocking element again drops before the locking element into the slide guide area of the support plate. 
     By sliding the seat backwards the rear fixing hook also releases the relevant fixing bolt. The seat can now be lifted out of the bearing blocks of the vehicle floor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be explained with reference to the two embodiments shown in the drawings in which: 
     FIG. 1 a  is a diagrammatic side view of a seat understructure with open lockings front and back which are connected by a coupling rod, after the insertion of the seat understructure in the bearing blocks of the vehicle floor; 
     FIG. 1 b  is a similar view to FIG. 1 a  but during the locking process; 
     FIG. 1 c  is a similar view to FIG. 1 a , but at the end of the locking process; 
     FIG. 2 a  is a diagrammatic side view of a seat frame after insertion in the bearing blocks of the vehicle floor and with locking elements analogous with FIG. 1, but with an additional blocking element for the front locking element; 
     FIG. 2 b  is a similar view to FIG. 2 a , but during the locking process; and 
     FIG. 2 c  is a similar view to FIG. 2 a  but at the end of the locking process. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The side view of FIG. 1 a  shows diagrammatically the structure of a seat understructure whose locking elements connect the vehicle seat to the vehicle floor through the fixing bolts  10   a ,  10   b  which belong to the bearing blocks  1   a ,  1   b . The diagrammatic illustration of the seat frame is restricted substantially to the guide rail  7  which is in positive-locking displaceable engagement with a guide rail mounted on a seat upper frame (not shown), and the support plate  2   a  which on one side is with its slide guide  20   a  part of the front locking and on the other side supports the locking element  3   a  in the swivel axis  30   a.    
     The rear seat fastening has a fixing hook  2   b  with a slide guide  20   b  open to the front for the fixing bolt  10   b . At first however the entrance to the slide guide  20   b  is blocked by the claws  33   b ,  34   b  of the primary locking element  3   b  which is pressed by a tensile spring  36   b  with its stop  37   b  against the secondary locking element. To this end the tensile spring  36   b  engages on an arm  35   b  opposite the claw area so that the claw  33   b ,  34   b  is drawn in the direction of the opening of the slide guide  20   b . In the illustrated position of the primary and secondary locking element  3   b ,  4 , the rear fixing bolt  10   b  passes as the seat is set down into the bearing socket  1   a ,  1   b  automatically between the claw-forming stops  33   b ,  34   b  of the primary locking element, and indeed even then when the seat is incorrectly set down and at first strikes with the edge  21   b  of the fixing hook  2   b  on the fixing bolt  10   b  or stops with the edge  22   b  on the bearing block  1   b.    
     In this starting position the front fixing bolt  10   a  adjoins the stop  21   a  which opens directly into the slide guide  20   a . A locking swivel movement of the locking element  3   a  must still not take place however just yet, since the hook  33   a  can still not grip the bolt  10   a  in this position. A tensile spring  36   a  suspended from the support plate  2   a  and engaging on the arm  31   a  does indeed exert a correspondingly aligned force on the locking element  3   a  but the swivel movement is blocked by a coupling rod  5  which is connected on one side to the arm  31   a  through its front suspension  310  and on the other side for articulated movement with the secondary locking element through its rear suspension. Through the coupling rod  5  thus not only are the kinematic developments of the front and rear locking elements co-ordinated but the spring force of the tensile spring  36   a  which is required for the functional reliability of the device according to the invention is passed on to the secondary locking element  4 . 
     FIG. 1 b  shows a further phase of the assembly and locking process in which the seat frame was pushed forwards by a certain amount. It can clearly be seen that the fixing bolt  10   b  is thereby pressed against the stop  34   b . The swivel movement of the primary locking element  3   b  about the axis  30   b  which is connected therewith leads to an increase in the tension of the spring  36   b  which is mounted between the seat frame and arm  35   b.    
     It can also be seen that the position of the front locking element  3   a  has still not changed up to this phase of the assembly process although the front fixing bolt  10   a  has already moved forward practically half way into the slide guide  20   a ; it is however still not yet in its ideal position. Movements of all the other elements  3   a ,  5  coupled thereto are also blocked through the likewise unchanged position of the secondary locking element  4 . This takes place so long as the stop of the secondary locking element  4  is not released from the curved section  31   b  of the primary locking element  30  and a rotation about the axis  40  is blocked. The contour of the curved section  31   b  preferably lies on a circular arc about the axis  30   b.    
     FIG. 1 c  shows the device in the completely locked state wherein both fixing bolts  10   a ,  10   b  have occupied their intended positions in the slide guides  20   a ,  20   b  and the locking elements  3   a ,  3   b  have locked these positions. 
     The swivel movement of the primary locking element  3   b  connected with the (compared to FIG. 1 b ) additional forward displacement of the seat leads solely to the fact that the curved section  31   b  is no longer in engagement with the stop  41  and thus a swivel movement driven by the spring  36   a  and transferred by the coupling rod  5  leads to rotation of the secondary locking element  4 . The secondary locking element  4  thereby swivels with its curved section  42  into a snug-fit curved section  32   b  of the primary locking element  3   b  whereby a resetting movement of the fixing bolt  10   b  or primary locking element  3   b  is reliably prevented. The position of the primary locking element  3   b  is in practice locked by the secondary locking element  4 . In order to guarantee a favourable force lock in the event of a rear impact crash the stop  33   b  for the bolt  10   b , the complementary faces of the curved sections  32   b ,  42  and the swivel axis  40  should lie roughly on one line. 
     At the same time as the swivel movement of the secondary locking element  4 , the swivel movement of the locking element  3   a  takes place which locks the bolt  10   a . The handle  32   a  thereby passes into a position which can be used to monitor the proper locking. Through renewed lifting of the handle  32   a  the locking is released at the front directly and at the back indirectly through the secondary locking element  4  swivelling back through the coupling rod. With the assistance of the spring  36   b  the seat can now be pushed backwards whereby the claw  33   b ,  34   b  of the primary locking element  3   b  which is swivelling forwards gradually releases the fixing bolt. Thus the seat and its locking elements pass into a position as shown in FIG. 1 a . The seat can now be lifted out of the bearing blocks  1   a ,  1   b  without problem. 
     FIGS. 2 a  to  2   c  show a further development of the embodiment described above in an analogous sequence of assembly processes which by adding a blocking element  6  has an increased standard of safety. It is guaranteed that the locking of the front fixing bolt  10   a  can also only take place when the bolt  10   a  has occupied the locking position already described. The release by the secondary locking element  4  of the primary element  3   b  pretensioned by the spring  36   b  can by itself alone still not lead to the front locking element  3 ′ a  swivelling in the area of the slide guide  20   a.    
     The blocking element  6  is mounted with its end remote from the locking element  3 ′ a  for swivel movement on the support plate  2   a  and prior to the start of the locking process (see FIG. 2 a ) covers the largest part of the slide guide  20   a  whereby the free end with the curved section  62  and nose  61  is in engagement with the projecting stop  34   a  of the locking element  3 ′ a  and supports this against swivelling in. A spring  63  presses the stops  34   a  and  61  towards each other. Even if the proposed locking position of the rear fixing bolt  10   b  in the slide guide  20   b  ought to have been occupied, this locking cannot take place though the secondary locking element  3   b  and the locking movement of the front locking element  3 ′ a . Even with moderate strain on the seat, for example by jolting against the backrest, it would become obvious that the seat is unlocked. Furthermore from the position of the handle  32   a  it can be concluded whether the seat locking has been properly completed or not. 
     If during the assembly process the contact of the front fixing bolt  10   a  with the stop  21   a  of the support plate  2   a  is maintained, during a forward displacement of the seat (see FIG. 2 b ) the bolt  10   a  gradually forces the blocking element  6  out of the area of the slide guide  20   a . The projecting stop  34   a  thereby slides on the curved section  62 ; the position of the locking element  3 ′ a  remains unchanged. 
     The locking mechanisms are preferably matched with each other so that the curved section  31   b  relative to the stop  41  in the rear locking area as well as the curved section  62  and the stop  34   a  in the front locking area come out of engagement roughly at the same time during the assembly process. The spring  36   a  drives the locking process whereby the stop  34   a  presses the blocking element  6  further against the spring  63  and the hook-shaped stop  33   a  engages underneath the fixing bolt  10   a.    
     On unlocking the seat the blocking element  6  falls again before the locking element  3 ′ a . Elsewhere the same applies as already mentioned for FIGS. 1 a  to  1   c.