Abstract:
A clamp for attaching a folded airbag constituting part of a vehicle occupant restraint system to a vehicle structure has a head for attachment to the vehicle structure and at least one arm adjoining the head for holding the airbag. To prevent an arm being broken away from a clamp, the clamp is of one-armed construction and the one arm is so shaped that the folded airbag, or a pouch containing it, is held at least partially between the single arm and the vehicle structure.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to a devices for attaching a side airbag, sometimes called a curtain airbag, to a vehicle or a vehicle structure. The invention further relates to an assembly of an airbag and a fastening device, such as a clamp for attaching a side airbag to a vehicle or a vehicle structure.  
         BACKGROUND OF THE INVENTION  
         [0002]    Clamps are used in vehicle occupant restraint systems that include an airbag, to attach the airbag in the folded state to a vehicle structure, such as for example the vehicle body. The clamps are used in particular with side airbags, in which the airbag is attached in the folded state along the supporting structure of an automobile for example between the A and B pillars or the A and C pillars on the side facing the inside of the vehicle. A tube-like pouch may surround the folded airbag and, with an inflator, forms an airbag module.  
         DISCUSSION OF THE PRIOR ART  
         [0003]    DE 200 20 097 U1 teaches a clamp for an airbag that has two metal arms. The two arms are connected by a head. They encompass a folded airbag on both sides, such that the airbag is held therebetween. The arms touch one another at the ends thereof remote from the head. When the airbag module is actuated, the airbag held by the clamp is filled very rapidly with gas. During this process, the arms of the clamp are bent apart with great force and at high speed, so that the airbag may pass between them and be deployed. The bending process may cause an arm to break off from the head.  
           [0004]    Clamps are also known in which two arms are substantially connected to the end area of the clamp remote from a head by a hinge. The two arms are again connected to the head of such a clamp by a retaining screw that connects the head to a vehicle. The hinge between the two arms takes the form of a predetermined breaking point. When the airbag module is actuated, this predetermined breaking point is opened and the airbag exits between the arms, while one of the arms is again forced with great power out of its rest position or deformed.  
         SUMMARY OF THE INVENTION  
         [0005]    There is provided in accordance with on aspect of the invention a device for attaching an airbag to a vehicle structure, the device comprising a head for attachment to the vehicle structure and at least one arm adjoining the head for holding the airbag, wherein the clamp is of one-armed construction and the one arm is so shaped that the folded airbag or a pouch containing the airbag is held at least partially between the single arm and the vehicle structure.  
           [0006]    There is provided in accordance with another aspect of the invention an assembly comprising an airbag and an attachment device for attaching the airbag to a vehicle structure, the airbag being contained in a pouch, the attachment device comprising a head for attachment to the vehicle structure and at least one arm adjoining the head for holding the airbag, wherein the attachment device is a clamp is of one-armed construction and the one arm is so shaped that the folded airbag or the pouch containing the airbag is held at least partially between the single arm and the vehicle structure.  
           [0007]    In known airbag clamp designs, a folded airbag is enclosed completely by two arms of a clamp and these two arms are moved apart during inflation of the airbag. According to the invention, on the other hand, a single arm is provided which is attached to the vehicle structure. The single arm holds the airbag or a pouch surrounding it relative to this vehicle structure. Upon deployment, the airbag attached in this way may either exit freely between the single arm and the adjoining vehicle structure or deploy freely at the side of the arm remote from the vehicle structure. An arm is neither bent open or deformed forcefully. Because bending open and deformation of clamp arms is prevented, less force is required for opening and inflating the airbag. This increases process reliability during opening.  
           [0008]    According to the invention, a predetermined breaking point on the clamp is also avoided. Therefore, unintentional damage to the airbag or opening of a predetermined breaking point cannot happen either. The risk of such unintentional damage arose previously during production and assembly of a clamp or during actuation of the airbag.  
           [0009]    The single arm provided according to the invention generally lies extensively against the vehicle structure and is thereby not exposed to any great load.  
           [0010]    The shape of the clamp according to the invention may moreover be produced with little material and with relatively simple tools. Its production costs are therefore altogether lower than with known clamps.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a longitudinal section through a first exemplary embodiment of a fastening device according to the invention.  
         [0012]    [0012]FIG. 2 is a longitudinal section through a second exemplary embodiment of a fastening device according to the invention.  
         [0013]    [0013]FIG. 3 is a front view of a vehicle occupant restraint system according to the invention with a plurality of above-mentioned fastening devices.  
         [0014]    [0014]FIG. 4 is a perspective view of a detail of a folded airbag with pouch, as used in the above-mentioned first exemplary embodiment.  
         [0015]    [0015]FIG. 5 is a perspective view of a detail of a folded airbag with pouch, as used in the above-mentioned second exemplary embodiment.  
         [0016]    [0016]FIG. 6 is a perspective view of an exemplary embodiment of a clamp according to the invention with a folded-open head.  
         [0017]    [0017]FIG. 7 is a perspective view according to FIG. 6 of the clamp with a closed head.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    FIGS.  1  to  7  show devices  10  for attaching or fastening an airbag  36  in particular a side airbag, that is part of a vehicle occupant restraint system to a vehicle structure  12 . Put another way, FIGS.  1  to  7  show exemplary assemblies of an airbag  36  and an attachment device  14  for attaching the airbag to a vehicle structure  12 , the airbag being contained in a pouch  38 . The vehicle occupant restraint system is located inside a vehicle such that it will be in the vicinity of the head of a vehicle occupant.  
         [0019]    The fastening device  10  according to FIG. 1 is provided with a clamp  14 , which comprises a head  16  and a single arm  18  adjoining the head  16 . The head  16  is subdivided into a first head portion  20  and a second head portion  22 , which may be folded relative to one another by a deformable hinge portion  24  and between which, in the folded-together state, there may be held a flap on the airbag or an airbag flap together with an additional flap on a pouch containing the folded airbag. The arm  18  extends from the second head portion  22 , which is spaced from the vehicle structure  12  by the first head portion  20 . Two through-holes  26 ,  28  are formed centrally in the head portions  20 ,  22 . The two through-holes  26 ,  28  are arranged coaxially when the first and second head portions  20 ,  22  are folded together. A screw  30  passes through the through-holes  26 ,  28  beneath the head of which screw  30  there is positioned a washer  32 . The screw  30  is screwed into a socket  34  in the vehicle structure  12  and thereby mounts the clamp  14  on the vehicle structure  12 , which is represented by a phantom line. By means of the flap or flaps attached in this way, a secure and lasting connection is achieved between the vehicle structure and the airbag. The connection remains reliably in existence even in the case of opening or inflation of the airbag.  
         [0020]    The fastening device according to the invention for an airbag may advantageously be designed with a pouch  38  containing the airbag  36 , into which pouch the single arm  18  of the clamp  14  projects. The arm thus grips the pouch so-to-speak from the inside out and is supported relative to the vehicle structure  12 . In this way, the pouch “hangs” on the single arm according to the invention.  
         [0021]    The fastening device  10  is attached to a portion of the vehicle structure  12  that comprises a substantially vertical and a substantially horizontal, downwardly directed area. The screw  30  attaches the head  16  to the vertical area of the vehicle structure  12 . The single arm  18  extending from and adjoining the head  16  is bent along the substantially horizontal, downwardly directed area and extends substantially parallel to the vehicle structure  12 .  
         [0022]    A folded airbag  36  is mounted on the arm  18 . The airbag  36  is arranged between the arm  18  and a substantially horizontal area of the vehicle structure  12 . The airbag  36  is contained in a pouch  38 , in which it is tightly packed. The pouch  38  is provided with an opening  40 , through which the arm  18  projects into the pouch  38 .  
         [0023]    Alternatively or in addition, a flap  42  may be provided on the airbag itself, which is held between two retaining portions of the head of the clamp. The flap  42  is formed on the airbag  36 , in the center of which flap there is punched a hole  44 . The flap  42  passes beside the arm  18  through the opening  40  to the head  16  of the clamp  14 . The flap extends between the two head portions  20 ,  22  as far as the vicinity of the hinge portion  24 . Between the two head portions  20 ,  22  the flap  42  of the airbag  36  is clamped in a non-interlocking manner on both sides by means of the screw  30 . The screw  30  additionally passes through the hole  44  in the flap  42 , such that an interlocking connection is also provided between screw and airbag.  
         [0024]    [0024]FIG. 2 shows an exemplary embodiment of a fastening device  10  that is constructed to a considerable extent in the same way as the fastening device according to FIG. 1. In this exemplary embodiment, the head  16  of the clamp  14  again consists of two head portions  20 ,  22 . However, in this exemplary embodiment the arm  18  starts from the head portion  20 , which lies against the vehicle structure  12 .  
         [0025]    In order further to improve mounting of the clamp and an associated folded airbag, a prefixing means, in particular a prefixing pin  46 , is advantageously provided on the arm  18  for preliminary attachment of the clamp to or pre-mounting thereof on the vehicle. With the prefixing means, the clamp may be clipped to the vehicle structure, until for example the flap has been arranged between the head portions of the clamp and fastened by a screw  30 . The arm  18  again extends substantially parallel to the surface of the vehicle structure  12 . In its area remote from the head  16 , the arm  18  is connected to the vehicle structure  12  by a prefixing pin  46 . The connection using the prefixing pin  46  is effected during mounting of the clamp  14 , before a screw  30  is screwed into the head portions  20 ,  22  through the corresponding through-holes  26 ,  28 .  
         [0026]    In the exemplary embodiment according to FIG. 2, the arm  18  is again inserted into the pouch  38  through an opening  40 . However, the opening  40  is formed in this case on the side or edge of the pouch  38  facing the vehicle structure  12 .  
         [0027]    A second opening  48  is formed in the pouch  38 , through which opening  48  the prefixing pin  46  passes. In addition, in the exemplary embodiment according to FIG. 2, the flap  42  is again formed on the airbag  36 . An additional flap  42 ′ may be formed on the pouch  38  (see also FIG. 5), which would then be arranged together with the flap  42  likewise at the head  16 .  
         [0028]    The arm  18  is inserted into the pouch  38  in such a way that the airbag  36  comes to lie against the side of the arm  18  remote from the vehicle structure  12 . Finally, at the end of the arm  18  remote from the head  16  there are also formed two hooks  50 , which engage the pouch  38  from inside in an interlocking manner prevent the arm  18  from sliding out of the pouch  38 . In addition, a hook for gripping part of the airbag or a pouch containing the folded airbag from behind is advantageously provided on the single arm. The hooks result in an interlocking connection between the airbag or the pouch and the vehicle structure. Detachment of the airbag from the vehicle is reliably prevented with this type of connection.  
         [0029]    [0029]FIG. 3 shows the overall arrangement consisting of airbag  36  with pouch  38  and clamps  14 , as attached to a vehicle structure in the head area of a vehicle occupant. An inflator  52 , with which the airbag  36  is inflated in a safety-critical situation, is arranged at one end of the airbag  36  folded in the manner of a tube. Alternatively or in addition, a flap may be provided on the airbag itself, which is held between two retaining portions of the head of the clamp.  
         [0030]    In addition to the above-mentioned flap for fastening the airbag, an additional flap may be provided particularly advantageously on such a pouch containing the airbag. The additional flap may likewise be held permanently between two retaining portions of the head of the clamp.  
         [0031]    [0031]FIGS. 4 and 5 show in detail how the flaps  42 ,  42 ′ are formed on an airbag  36  or on a pouch  38 .  
         [0032]    The flap  42  according to FIG. 4 is attached to the airbag  36  and passes outwards through an oblong opening  40  in the pouch  38 . The pouch  38  is laid tightly around the airbag  36  and closed in the manner of a tube by a seam  54 . When the airbag  36  is inflated by the inflator  52 , the seam  54  is torn open and the airbag  36  is deployed out of the pouch  38 . In the exemplary embodiment according to FIG. 1, it passes downwards out of the gap between the arm  18  and the vehicle structure  12 .  
         [0033]    [0033]FIG. 5 shows an exemplary embodiment in which an additional flap  42 ′ is provided on the pouch  38  beside the flap  42  (not illustrated) on the airbag  36 . The additional flap  42 ′ is formed out of the fabric of the pouch  38 , wherein an opening  40 ′ is formed. The opening  40 ′ may be formed particularly simply and economically at the additional flap in the airbag containing pouch by cutting the additional flap out of the pouch. In this way, in only one step, the flap is cut out and at the same time the opening is formed through which the single arm according to the invention is subsequently introduced into the pouch.  
         [0034]    The opening  40 ′ corresponds in function to the opening  40 , such that the arm  18  may subsequently be pushed therethrough into the pouch  38 . The flap  42 ′ comprises a hole  44 ′ thererthrough, as does the flap  42  on the airbag  36 . When the flap  42 ′ is arranged at the head  16 , the shank of the screw  30  is passed through this hole  44 ′ and the flap  42 ′ is attached in this way beside the flap  42  between the head portions  20 ,  22 . Thus the pouch can be gripped “from the inside out” by means of the single arm  18  such the single arm of the clamp projects into the pouch. The flap then extends directly in the vicinity of the arm along the clamp to the head thereof. Thus, a compact and permanent connection is formed between clamp, pouch and folded airbag.  
         [0035]    [0035]FIGS. 6 and 7 are perspective, detailed views of a clamp. Of particular note is the tapered hinge portion  24  between the two head portions  20 ,  22 . In addition, the hooks  50  are formed in such a way that they project outwards to the sides. In the case of the clamp  14  according to FIGS. 6 and 7, the prefixing pin  46  may be arranged displaceably in channels  56 , in order to allow post-adjustment of the clamp  14  on the vehicle structure  12  prior to screwing in of the screw  30 .  
         [0036]    While there have been described what are believed to be the preferred embodiments of the present invention, those skilled in the art will recognize that other and further changes and modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the true scope of the invention.