Abstract:
An airbag module comprising a planar airbag and an elongate gas generator including discharge ports at least partially extending into the airbag. The airbag includes two side walls connected together by an edge region and made of fabric. An opening is disposed in the edge region of the airbag. The gas generator extends through the opening such that an elongate first section of the gas generator is arranged inside the gas bag. A gas-conducting element protects the fabric and is located in the airbag adjacent the opening. The gas-conducting element is made of plastic and includes a forward section having an arcuate cross section including an opening formed between at least two substantially parallel legs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to German patent application serial number 102004022740.3 filed May 7, 2004 and PCT/EP2005/004865, filed May 4, 2005. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an airbag module for use in a motor vehicle. 
     2. Description of the Related Art 
     Side curtain airbags and other side airbags are used to protect vehicle passengers in the event of a side impact or a vehicle rollover accident. Side curtain airbags are disposed on the roof pillar of the vehicle and when inflated cover at least one side window and, if necessary, the B-pillars of the vehicle. These airbags are particularly designed for providing protection for an occupant&#39;s head and upper torso. Another type side airbags may also be disposed in the vehicle seat and, when needed, inflate between the passenger&#39;s upper body and the side vehicle structure. These two airbag types have in common that they are built planar with two side walls connected by an edge region, in contrast to front airbags, which are generally pillow-shaped. In this type of airbag, a gas generator, which is elongated and extends into the airbag through an opening, usually provides the gas supply. To this end, the gas generator is disposed partially within and partially outside the airbag. The opening through which the gas generator extends is located in the edge region in which two side walls of the airbag are connected together. 
     The gas generator is usually elongated. The area of the airbag in which the opening is located is L-shaped. The gas generator extends parallel to the longitudinal direction of the airbag. Since the discharge ports of the usually cylindrical wall of the gas generator are generally disposed rotationally symmetric for safety reasons (thrust neutrality), there arises the problem that the gas-bag fabric in the vicinity of the opening is greatly stressed by discharged gases. 
     It is known to provide a mounting made of sheet metal, which on the one hand holds the gas generator on the vehicle structure and, on the other hand, extends into the opening of the gas bag and partially surrounds the area of the discharge ports and thus protects the adjacent fabric. 
     Besides a relative high cost of assembly, this sheet metal element extending into the airbag has the disadvantage that it can damage the fabric of the airbag during the frequently long periods of time in which the airbag has been installed in the vehicle and is subjected to various shocks and vibrations. In the worst case, this may lead to failure of the airbag. 
     Proceeding herefrom, it is the object of the invention to provide an improved airbag module to reduce the potential for damage to the airbag during deployment. 
     SUMMARY OF THE INVENTION 
     According to the invention, an airbag module includes a gas-conducting element made of plastic connected to the fabric of the airbag in the area of a gas generator opening. To this end, the gas-conducting element is provided with an arcuate cross-section including an opening. Legs of the arcuate section are particularly suitable for connection to the fabric of the airbag, for example, by sewing. 
     By using a gas conducting element made from an appropriate plastic, polyamide or polypropylene for example, damage to the airbag fabric is prevented, even during lengthy storage. Elasticity may be maintained by choosing a suitable wall thickness, between, for example, 0.4 mm and 0.8 mm. In another example, the wall thickness may be between 1.5 mm and 2.5 mm. 
     In another embodiment, a gas generator is particularly easy to assemble into the airbag by providing a locking projection. 
     Another advantage of the airbag module according to the invention is that it prevents incorrect orientation of the gas-conducting element during final assembly. 
     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal section through a side curtain airbag; 
         FIG. 2  is the gas-conducting element depicted in  FIG. 1 ; 
         FIG. 3  is an opening area of the side curtain airbag including a gas generator; 
         FIG. 4  is the gas generator of  FIG. 3  shown inserted into the gas-conducting element of  FIG. 2 ; 
         FIG. 4   a  is an alternate embodiment of  FIG. 4 ; 
         FIG. 5  is a longitudinal section along the plane A-A depicted in  FIG. 4 ; 
         FIG. 6   a  is another exemplary embodiment of the gas-conducting element in a perspective view; and 
         FIG. 6   b  is a longitudinal section through the gas-conducting element depicted in  FIG. 6   a  along the plane E. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a longitudinal section through a side curtain airbag  10 . The side curtain airbag  10  is provided with two side walls (of which a side wall  12  is shown), which are connected together in an edge region  14 , for example, by sewing. An upper edge  14   a  of the edge region  14  includes an opening  16  for inserting a gas generator  30  (see  FIG. 3 ) and tabs  18  for attaching the side curtain airbag  10  to a roof of a motor vehicle (not shown). The side curtain airbag  10  has intermediate seams  22  for contouring the airbag  10  and tethers  20  for positioning of the inflated airbag  10  in front of a side window of the motor vehicle. 
     An opening area  24  is L-shaped to permit the use of an elongated gas generator. The opening area  24  is approximately in the center of the top edge  14   a  and includes the opening  16  into the airbag  10 . The gas generator  30  extends partially into the opening  16  and is arranged parallel to the longitudinal direction of the airbag  10 . 
     A gas-conducting element  40  (illustrated schematically in  FIG. 1 ) is provided within the L-shaped opening area  24 . The gas-conducting element  40  is made of, for example, polyamide and is connected to the fabric of the airbag  10  in the opening area  24 . The gas-conducting element  40  is connected inside the airbag  10 , for example by sewing, when the airbag  10  is completed so that it can no longer slip to the side during final assembly. Sewing the gas-conducting element  40  in place is one method of connection, but the required connection can also be produced by welding or gluing. 
     Turning to  FIG. 2 , the gas-conducting element  40  is provided with a forward section  42  and a rear section  45 . The cross section of the forward section  42  is arcuate and includes an opening directed toward an interior of the airbag  10  when connected to the airbag  10 . This results in a U-shaped cross section including two substantially parallel legs  42   a  and  42   b . The gas-conducting element  40  is preferably sewn to the adjacent fabric in the area of the legs  42   a  and  42   b.    
       FIG. 2  is a perspective illustration of the gas-conducting element  40 . Here the rear section  45 , has a substantially circular cross section. The forward section  42 , which has the arcuate or U-shaped cross section discussed above, is also easily recognized. During assembly, the gas generator  30  (not shown) is pushed through the rear section  45  and locks into a locking projection  46 . A slot  47  provides elasticity in the rear section  45  required for the locking projection  46  to function properly. The two legs  42   a  and  42   b  to which the airbag  10  is connected, are also shown. 
       FIGS. 3 and 4  depict the gas generator  30  inserted into the opening  16  of the airbag  10 . As can be seen, the gas generator  30  is elongated and rotationally symmetric. A first section  32  projects into the airbag  10  and is provided with discharge ports  33 . The discharge ports  33  are partially surrounded by the forward section  42  of the gas-conducting element  40 . The first section  32  is provided with a notch  34 , which is mechanically coupled to the locking projection  46  of the gas-conducting element  40 . The second section  35  is located outside of the airbag  10 . 
     It would also be conceivable to use an angled gas generator (not shown) as long as the first section  32  projecting into the airbag  10  is similarly elongated. 
       FIG. 4   a  depicts a variation of the embodiment shown in  FIG. 4 . As in the other embodiments, the gas-conducting element  40  is connected directly to the fabric of the airbag  10  by either sewing, gluing or welding. This connection is in the area of the legs  42   a  and  42   b . A strap  50 , additionally secures the airbag  10  to the gas generator  30 . The strap  50  clamps the rear section  45  of the gas-conducting element  40  to the second section  35  of the gas generator  30 . The gas-conducting element  40  is thereby connected directly to the airbag  10  and to the gas generator  30 . This arrangement increases the strength of the connection between the gas generator  30  and the airbag  10 . 
       FIG. 5  depicts a longitudinal section through  FIG. 4  or  4   a  along the sectional plane A-A. This view shows how the arcuate or U-shaped forward section  42  of the gas-conducting element  40  protects the fabric of the surrounding airbag  10  from a discharged gas  32   a . The forward section of the gas-conducting element  40  surrounds a certain area of the external wall of the first section  32 , so that the gas-conducting element  40  deflects the gas  32   a  flowing out of the discharge openings  33 . The legs  42   a  and  42   b  direct the gas into the airbag  10 . The gas  32   a  goes from the discharge ports located in the bottom section of the external wall into the airbag  10 . 
     It is also possible to see the connecting areas  43  by which the legs  42   a  and  42   b  are connected to the fabric of the airbag  10 . To simplify the connecting process, the legs  42   a  and  42   b  of an alternate embodiment of the forward section  42  of the gas-conducting element  40  can be arranged approximately perpendicular to a direction of gas flow from the arcuate portion of the forward section  42  to form an Ω-shaped cross section instead of the U-shaped cross section. Far ends of the D-shaped cross section are fastened to the fabric of the airbag  10 . 
     The locking of the gas generator  30  into the locking projection  46  provides mechanic feedback during assembly to ensure that the gas generator is located in the correct axial position. Because of the rotationally symmetrical design of the gas generator, radial alignment of the gas generator with respect to the curtain gas bag is not an issue. This simplifies the assembly of the gas generator  30  into the side curtain airbag  10 . 
       FIGS. 6   a  and  6   b  depict another exemplary embodiment of a gas-conducting element  40 .  FIG. 6   b  is a longitudinal section along the plane E through the forward section  42  of the gas-conducting element in  FIG. 6   a . In the gas-conducting element of this exemplary embodiment, both the forward section  42  and the rear section  45  are tubular. The forward section  42  is provided with an elongated hole  48  through which at least a portion of the gas coming from the gas generator  30  flows into the airbag  10 . A base plate  49  is located in the plane of the elongated hole  48 . A longitudinal section through the forward section  42 , including the legs  42   a  and  42   b  projecting from the sides of the forward section  42 , result in the Ω-shaped cross section shown in  FIG. 6   b . Braces  50  may optionally be provided to increase stability. Here the connection of the gas-conducting element  40   a  to the fabric of the airbag  10  is in the area of the legs  42   a  and  42   b  permitting the entire area of the base plate  49  to be connected to the airbag  10 . 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.