Abstract:
A gas bag module has a carrier part, a gas bag having an inflation opening that is surrounded by a rim and a gas bag retainer element, where the rim of the inflation opening is arranged between the gas bag retainer element and the carrier part. At least one fixing element coupled to the gas bag is arranged at the rim of the inflation opening. The fixing element, seen in a radial sectional view, is at least partially wedge-shaped or trapezoidal and is oriented with respect to the gas bag retainer element and to the carrier part such that the fixing element, when the gas bag is stressed, seeks to move the carrier part and the gas bag retainer element away from each other by a motion between the carrier part and the gas bag retainer element, based on a wedge effect.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a gas bag module.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is known to provide a gas bag module with a gas bag retainer element that clamps a rim of an inflation opening of the gas bag between itself and a carrier part. A fixing element coupled to the gas bag and arranged at the rim of the inflation opening is used to enhance the clamping effect. Using such a fixing element, the attachment of the gas bag to a carrier part, which can be, e.g., a part of a module housing, is improved, above all in response to stress that acts upon the gas bag, e.g., when the gas bag is deployed or when a vehicle occupant impacts upon the gas bag. In both cases, it is crucial that the rim of the inflation opening remain reliably attached to the carrier part in the most gas-tight fashion possible.  
       BRIEF SUMMARY OF THE INVENTION  
       [0003]     It is an object of the present invention to optimize the fixing of a gas bag on a carrier part.  
         [0004]     This is achieved in a gas bag module having a carrier part, a gas bag having an inflation opening that is surrounded by a rim and a gas bag retainer element, where the rim of the inflation opening is arranged between the gas bag retainer element and the carrier part. At least one fixing element coupled to the gas bag is arranged at the rim of the inflation opening. The fixing element, seen in a radial sectional view, is at least partially wedge-shaped or trapezoidal and is oriented with respect to the gas bag retainer element and to the carrier part such that the fixing element, when the gas bag is stressed, seeks to move the carrier part and the gas bag retainer element away from each other by a motion between the carrier part and the gas bag retainer element, based on a wedge effect.  
         [0005]     Using this configuration, the fixing element, if necessary, can move a small distance radially to the outside if stress acts upon the gas bag, the clamping action exerted upon the gas bag by the retainer element and the carrier part gradually increasing. The gas bag therefore is not braked in a jerky fashion, so that the maximum forces acting upon the rim of the inflation opening are reduced in comparison to a known gas bag attachment means. In addition, as a result of at least one clamping surface, which is sloped with respect to the axis of the gas bag module and is configured on the wedge-shaped or trapezoidal section, the forces are redirected in the axial direction, so that part of the stress forces can be absorbed by an attachment device of the gas bag retainer element on the carrier part, e.g., a known screw connection. Because the clamping action increases in proportion to the force acting upon the gas bag when the fixing element moves between the gas bag retainer element and the carrier part, the clamping force acting upon the rim of the inflation opening automatically increases. Therefore, the level of biasing that is exerted by the aforementioned attaching means upon the rim of the inflation opening is no longer solely responsible for the fixing of the gas bag, in the event of stressing.  
         [0006]     When the gas bag is subjected to stress, the fixing element may be clamped, e.g., between the carrier part and the gas bag retainer element and may be ultimately positioned so as to be immovable.  
         [0007]     It is possible to use an annular fixing element, which completely surrounds the inflation opening. However, it is also possible, alternatively, to provide a plurality, e.g., four or five, fixing elements that are separate from each other and that are arranged at locations that are distributed over the circumference of the inflation opening. In this case, the fixing element can be configured as an annular segment, in order to achieve a uniform clamping action. The fixing element could also be configured as a slotted ring.  
         [0008]     “Annular” here should not be understood as referring only to circular ring-shaped component parts, but rather generally also to other shapes having a recess on the inside.  
         [0009]     To achieve a specific clamping effect, it is advantageous if the fixing element is inherently stable, i.e., in response to clamping, it does not become deformed, or does so only to a minor degree. The wedge-shaped or trapezoidal section is designed to have this shape even in an unstressed state and not to adopt it only during a clamping process.  
         [0010]     Preferably, the fixing element is a separate component part and is not designed so as to be integral, e.g., with the gas bag or the gas bag retainer element.  
         [0011]     The fixing element can be embedded in the rim of the inflation opening, e.g., by being sewn or woven in. The fixing element can also be joined to the gas bag by bonding, either as the exclusive attachment or in addition to being sewn or woven in.  
         [0012]     It is also possible to carry out the coupling of the fixing element to the gas bag in that a side of the fixing element that is oriented toward the rim of the inflation opening is roughened or suitably patterned in order to increase the friction between the fixing element and the gas bag fabric. In this case, it is possible to do without a further attachment means.  
         [0013]     In one preferred embodiment of the present invention, the gas bag retainer element and/or the carrier part in the area of the rim of the inflation opening have a contour that corresponds to the slope of the fixing element. Thus when the gas bag is stressed, both a very uniform clamping action as well as a uniformly increasing stress on the rim of the inflation opening are achieved. In this context, it is not important whether the sloped clamping surface is configured on the side oriented toward the gas bag retainer element, the side oriented toward the carrier part, or on both sides of the fixing element. What is important here is that the contour of an accommodation space, which is formed between the carrier part and the gas bag element and in which the fixing element is arranged, corresponds to the exterior contour of the fixing element. Thus, when the gas bag is stressed and there is a motion of the fixing element, resulting therefrom, that is radially directed to the outside, a uniform clamping action is generated between the clamping surface(s) and the interior side of the accommodation space, and additionally a uniformly distributed and uniformly increasing force is exerted upon the rim of the inflation opening.  
         [0014]     The gas bag can be clamped between the gas bag retainer element and the carrier part in an area adjacent to the rim of the inflation opening, so as to assure its fixation on the carrier part, irrespective of a stressing of the gas bag.  
         [0015]     In addition, the gas bag retainer element can be a separate gas bag retainer ring, but it can also be configured on a flange of a gas generator or on another suitable component part. The carrier part of the gas bag module is usually formed by a generator carrier, a housing, or another part of the gas bag module, which is ultimately connected to a vehicle-fixed component part, e.g., a steering wheel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     In the drawings:  
         [0017]      FIG. 1  depicts a schematic half-side sectional view of a gas bag module according to the present invention;  
         [0018]      FIG. 2  depicts an enlarged detail from  FIG. 1 ;  
         [0019]      FIG. 3  depicts an enlarged detail from  FIG. 2  according to a first variant of a gas bag module according to the present invention;  
         [0020]      FIGS. 3   a  to  3   c  depict fixing elements of a gas bag module according to the invention in diverse designs;  
         [0021]      FIG. 4  depicts an enlarged detail from  FIG. 2  according to a second variant of a gas bag module according to the present invention; and  
         [0022]      FIG. 5  through  FIG. 10  depict further possibilities for attaching a gas bag to a carrier part. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0023]      FIG. 1  shows a gas bag module  10  that is inserted in a steering wheel  12 . Gas bag module  10  contains a folded gas bag  16  that is accommodated in a cup-shaped carrier part  14 . A rim  18  of an inflation opening of gas bag  16  is situated between a base  17  of carrier part  14  and a separate, annular gas bag retainer element  20 . Base  17  of carrier part  14  has an opening, in which a gas generator  22  is inserted, which has an annular flange  24  (see also  FIG. 2 ), which is also arranged between gas bag retainer element  20  and base  17  of carrier part  14 .  
         [0024]     In gas bag retainer element  20 , in rim  18  of the inflation opening of gas bag  16 , as well as in base  17  of carrier part  14 , openings are provided, through which extend attachment means  26  configured as nut-and-bolt connections, which fixedly join these parts to each other.  
         [0025]     An rim area  28  of gas bag retainer element  20  situated in the interior in a radial direction R is bent upwards in an axial direction A of gas bag module  10 , so that flange  24  of gas generator  22  can be gripped by it and clamped under it.  
         [0026]     Between rim area  28  of gas bag retainer element  20  and base  17  of carrier part  14 , an accommodation space  30  is formed (see  FIGS. 3 and 4 ), in which a fixing element  32  is arranged. Fixing element  32  is coupled to rim  18  of the inflation opening of gas bag  16 .  
         [0027]     In the case depicted here, in circumferential direction U, a plurality of fixing elements  32 , separate from each other, are arranged at specific locations (see  FIG. 3   a ). However, it would also be possible to provide a single annular fixing element  32 , that also could be slotted in the radial direction R (see  FIG. 3   b ).  
         [0028]     Each fixing element  32  is a separate, inherently stable component part, that is made of, e.g., plastic or metal.  
         [0029]     Fixing element  32  tapers in the radial direction R in a wedge-shaped fashion and has a clamping surface  34 , which is radially sloped to the outside, seen in a sectional view in the radial direction R and with respect to the axial direction A, so that tip  36  of the wedge points radially to the outside.  
         [0030]     As can be discerned in  FIGS. 2 through 4 , the contour of base  17  of carrier part  14  and of gas bag retainer element  20  in the area of accommodation space  30  is fitted to the contour of fixing element  32 , in particular, to the slope of clamping surface  34 .  
         [0031]     Upon a stressing of the gas bag  16 , e.g., upon its deployment in case of activation of gas bag module  10 , or upon impact of a vehicle occupant on the inflated gas bag  16 , rim  18  of the inflation opening is radially stressed to the outside at least at a few locations over its circumference. This stressing is transmitted to fixing element  32 , so that the latter also moves radially to the outside. In the process, the wedge-shaped section of fixing element  32 , by clamping surface  34 , contacts the interior side of accommodation space  30 , in this case the interior side, oriented toward carrier part  14 , of edge area  28  of gas bag retainer element  20 . As a result of the contours that are coordinated with each other, fixing element  32  is displaced uniformly and continuously between gas bag retainer element  20  and carrier part  14 , and it moves these parts in an axial direction A away from each other. In this context, the result is a uniform clamping force between gas bag retainer element  20 , carrier part  14 , rim  18  of the inflation opening, and fixing element  32 , via which gas bag  16  is reliably attached to the carrier part. If the stress upon gas bag  16  is increased, then the clamping force is increased uniformly and without jerky motions, because fixing element  32  is pulled into accommodation space  30 , which radially tapers to the outside. Resulting from this is a very uniform stressing for fixing rim  18  of gas bag  16  in place.  
         [0032]     In the variant shown in  FIG. 3 , fixing element  32  is supported on rim  18  of the inflation opening and is coupled to rim  18  of gas bag  16  in that the side of fixing element  32  that is oriented toward rim  18  is roughened or suitably patterned in order to achieve a high degree of friction on the fabric of gas bag  16  (schematically depicted in  FIG. 3   c ).  
         [0033]     Alternatively, it is shown in  FIG. 4  to weave fixing element  32  into rim  18  of the inflation opening of gas bag  16  (see reference numeral  38 ) or to sew it through stitches  40  into rim  18  of gas bag  16 .  
         [0034]     Fixing element  32  can also be joined to rim  18  of the inflation opening by an adhesive  42 . An adhesive joint can be used either in addition to another attachment method, or it can function as the exclusive method of attaching fixing element  32  to gas bag  16 .  
         [0035]     In the embodiments depicted in  FIGS. 3 and 4 , fixing element  32  is inherently rigid and so stable that it is not deformed, or only insignificantly, when gas bag  16  is stressed. The wedge-shaped section has this shape even in the absence of a stressing of gas bag  16 .  
         [0036]     In the example depicted here, the fixing element has a sloped clamping surface  34  only on one side. It is of course equally conceivable to configure a further clamping surface on the side of fixing element  32  that is axially opposite, or, on the other hand, to configure the clamping surface only on the side of fixing element  32  that is oriented to base  17  of carrier part  14 . Tip  36  of fixing element  32  can also be oriented diagonally with respect to axial direction A. In this case, the contour of accommodation space  30  must of course be adjusted accordingly.  
         [0037]     It would also be conceivable to use a fixing element  32  having a trapezoidal cross section (see  FIG. 3   c ) or a clamping surface  34  having a non-linear, e.g., convex or concave slope. Equally, in radial direction R as well as in peripheral direction U only one section of fixing element  32  can be configured in a wedge or trapezoidal shape.  
         [0038]     In  FIGS. 5 through 10 , further possibilities are shown to attach an rim  118  of an inflation opening of a gas bag between two component parts, e.g., a carrier part  117  and a gas bag retainer element  120 .  
         [0039]     In the example depicted in  FIG. 5 , gas bag retainer element  120  has a projection  150 , whereas in carrier part  117  a groove  152  is configured corresponding to projection  150 . In response to a stressing of rim  118  of the gas bag, a clamping results of rim  118  of the inflation opening of the gas bag in the area of projection  150  and of groove  152 .  
         [0040]     In the example depicted in  FIG. 6 , in gas bag retainer element  120  a recess  160  is provided, which constitutes an accommodation space for a thickened portion in rim  118  of the inflation opening, the thickened portion being formed by stitches  162 . When stress is exerted upon rim  118 , the thickened portion is pulled radially to the outside and is clamped at sloping interior wall  164  of recess  160 .  
         [0041]     The example depicted in  FIG. 7  combines the fixing methods of  FIGS. 5 and 6 . Here, in gas bag retainer element  120 , seen radially to the inside, a recess  160  for accommodating a thickened portion formed by stitches  162  follows a projection  150 . Configured in carrier part  117  is a groove  152  corresponding to projection  150 .  
         [0042]     In the example depicted in  FIG. 8 , a fixing element  180  having a circular cross section is provided, which is separate from the other component parts depicted, and that is arranged in a groove  182  in carrier part  117 . Rim  118  of the inflation opening runs between fixing element  180  and carrier part  117 . In case of a tensile load upon rim  118  in radial direction R, a clamping action results between carrier part  117  and fixing element  180 .  
         [0043]     The example depicted in  FIG. 9  essentially corresponds to the example from  FIG. 8 , with the difference that a recess  194  is also provided in gas bag retainer element  120  that corresponds in its contour to the cross section of fixing element  180 .  
         [0044]     The example depicted in  FIG. 10  essentially corresponds to the example depicted in  FIG. 9 , with the difference that fixing element  200  has a rectangular cross section, and that recesses  202 ,  204  in gas bag retainer element  120  and carrier part  117 , respectively, are sloped only on the side that is oriented radially to the outside, and they run towards each other, whereas their distance on the radially interior side remains larger.  
         [0045]     Radial direction R as shown relates to all  FIGS. 5 through 10 .  
         [0046]     In all the examples depicted in  FIGS. 5 through 10 , the clamping action upon rim  118  of the inflation opening of the gas bag, which is exerted by carrier part  117  and gas bag retainer element  120 , is intensified by an appropriate shape of these two component parts, of rim  118  of the gas bag or of an additional separate fixing element  180 ,  200 .  
         [0047]     It would also be possible to combine one or more of the attachment methods depicted in  FIGS. 5 through 10  with the gas bag attachment depicted in  FIGS. 1 through 4 . Likewise, the elements of the diverse embodiments can of course be freely combined with each other at the discretion of a person skilled in the art.