Patent Publication Number: US-2005134021-A1

Title: Gas bag module

Description:
FIELD OF THE INVENTION  
      The invention relates to a gas bag module for a safety arrangement in vehicles, comprising a gas bag having at least two chambers separated from each other by a separating seam and a mounting opening formed in one of the chambers, and comprising a gas generator mounted at least partially in the mounting opening and having a housing which comprises a diffusor section associated with the chambers and a fastening section for installing the gas generator securely with the vehicle.  
     BACKGROUND OF THE INVENTION  
      A gas bag module disclosed in DE 298 22 159 U1 concerns in particular a gas bag side impact protection arrangement, which protects a vehicle occupant in a side impact from contact with the side structure of a vehicle or with penetrating vehicle parts. The known protection arrangement comprises a two-chambered gas bag, the first chamber of which extends in the inflated state to the side of the chest of a vehicle occupant and the second chamber of which in the inflated state protects the pelvic region of the vehicle occupant. The chambers can be filled so that in the filled state they have different internal pressures. For this purpose, the chambers are separated from each other by a separating seam which must lie closely against the housing of the gas generator which is introduced into the gas bag, in order to avoid an undesired pressure equalization. The dimensions of the gas generator housing and of the gas bag must therefore be coordinated very precisely with each other. Owing to the small tolerances of these dimensions, the installation of the gas generator involves considerable manufacturing expenditure. This manufacturing expenditure is further increased in that the fastening tongues present on the gas generator housing must be inserted in succession through openings in the gas bag wall.  
     SUMMARY OF THE INVENTION  
      By comparison, the invention provides a gas bag module which is able to be installed simply, with a secure sealing of the chambers with respect to the gas generator housing.  
      According to the invention, a gas bag module is provided for a safety arrangement in vehicles, comprising a gas bag, which has at least two chambers separated from each other by a separating seam, and has a mounting opening formed in one of the chambers, and comprising a gas generator, mounted at least partially in the mounting opening and having a housing which comprises a diffusor section associated with the chambers and a fastening section for mounting the gas generator securely with the vehicle, and which is characterized in that the fastening section, mounted inside the mounting opening, adjoins a wall section of the mounting opening and that further a fastening means is provided which fixes the wall section from the exterior of the mounting opening on the fastening section and acts upon the separating seam with tension and secures it on the diffusor section.  
      Owing to the invention, it is possible to construct the mounting opening larger than in the prior art and during the installation to also increase the distance of the separating seam, which separates the two gas bag chambers from each other, to the gas generator housing. Therefore, the gas generator with its housing can be pushed more easily into the mounting opening. In addition, the necessity for having to guide the fastening tongues on the gas generator through openings provided in the gas bag wall is eliminated, because the fastening section remains inside the gas bag. Through the greater structural space available, the mounting of the gas bag module can also be automated. Nevertheless, the invention ensures a secure sealing of the separating seam on the gas generator housing, so that no gas can overflow from one chamber into the other chamber. Therefore, on the one hand high internal pressures can be achieved and, on the other hand, higher pressure differences.  
      Finally, the invention permits a more flexible mounting of the gas generator in the gas bag, because the mounting opening in the gas bag can be fixed at any desired site of the gas generator housing. Therefore, for example, it is possible to keep the connector side of the gas generator freely accessible from the exterior, whereby also the further installation processes at the vehicle manufacturer is facilitated.  
      According to a preferred embodiment of the invention, the gas generator is a tubular gas generator and the gas bag is a two-chambered side gas bag. Advantageously, the diffusor section of the gas generator housing is adapted for filling the chambers with a different pressure distribution. This can be achieved for example in that—as described in DE 298 22 159 U1—the gas passage openings associated with the respective chambers have a different free overall cross-section. As an alternative to this, different quantities of gas can also be supplied to the respective diffusor sections, for example with the use of a multiple-stage gas generator. In this way, a restraint effect can be achieved which is optimally adapted to the different areas of the vehicle occupant&#39;s body. The gas generator housing with the diffusor section and the fastening section can be an integral component part of the gas generator. However, a part which is separate from the gas generator, which is securely connected with the gas generator and thus forms a structural unit therewith, is preferred.  
      In a particularly preferred embodiment, the fastening section of the gas generator housing lies opposite the diffusor section and is constructed as a flat, radially projecting fastening tongue running along the housing.  
      Preferably the fastening tongue is formed in one piece with the gas generator housing. It can be formed continuously or divided into several sections lying in the same plane.  
      The fastening means, which fixes the wall section of the mounting opening from the exterior on the fastening section, is formed from two opposite strips in a simple embodiment. Thereby, a particularly simple installation, able to be automated, of the gas bag is possible. For this, the strips are applied from the exterior onto the fastening section on the gas generator housing and thereby clamp between them the wall section adjoining the fastening section and the fastening sections. Through this process, the slack present at the mounting opening or in the region of the separating seam is eliminated and the separating seam is drawn in the direction of the gas generator housing or the diffusor section. Thereby, a reliable sealing of the gas bag chambers with respect to each other is ensured. The fastening of the gas bag module can take place by means of fastening points provided on the strips, which correspond to fastening points on the fastening tongue.  
      Instead of two separate strips, the fastening means can also be one strip with a U-shaped cross-sectional profile, which preferably has a perforated fold. To install the gas bag module, the U-shaped profile strip is placed with its free arms onto the fastening tongue on the gas generator housing, so that the wall section of the mounting opening adjoining the fastening tongue is clamped between the arms. For easier installation, the profile strip can also be bent up onto the fastening tongue. This process is substantially facilitated by the perforation in the fold. Also in this embodiment, the fastening to the vehicle can take place by means of fastening points provided on the strip, which correspond to fastening points on the fastening tongue of the gas generator housing.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Further features and advantages of the present invention will be apparent from the following description of a preferred embodiment in connection with the drawings, to which reference is made. In the drawings:  
       FIG. 1  shows a perspective view of the gas bag module according to the invention, in non-activated state;  
       FIG. 2  shows a side view of the gas bag of the gas bag module according to the invention, in unfolded state;  
       FIG. 3  shows a side view of the gas distributor housing of the gas bag module according to the invention;  
       FIG. 4  shows a second side view of the gas distributor housing;  
       FIG. 5  shows a third side view of the gas distributor housing;  
       FIG. 6  shows a sectional view of the gas distributor housing along the line I-I in  FIG. 3 ;  
       FIG. 7  shows a sectional view of the gas distributor housing along the line II-II in  FIG. 3 ;  
       FIG. 8  shows a sectional view of the gas distributor housing along the line III-III in  FIG. 4 ;  
       FIG. 9  shows a diagrammatic sectional view of the gas bag module according to the invention before the installation of the fastening strip;  
       FIG. 10  shows a diagrammatic sectional view of the gas bag module after the installation of the fastening strip;  
       FIG. 11  shows a side view of the fastening strip of the gas bag module according to the invention;  
       FIG. 12  shows a second side view of the fastening strip;  
       FIG. 13  shows a third side view of the fastening strip; and  
       FIG. 14  shows a sectional view of the fastening strip along the line IV-IV in  FIG. 11 . 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT  
      The gas bag module  10  shown in non-activated state in  FIG. 1  has an inflatable gas bag  12  and a gas generator  14 . The gas generator  14  has a housing which is constructed here as a separate gas distributor housing  24  and is securely connected with the gas generator  14 . The gas distributor housing  24  and the gas generator  14  incorporated therein are mounted together in a mounting opening  22  of the gas bag  12 . By means of a strip  44  installed on the back rest of a vehicle seat (not illustrated) so as to be secure with the vehicle, the gas bag  12  is connected securely with the gas generator  14  and the gas distributor housing  24 .  
      The gas bag  12  shown in  FIG. 2  in the unfolded state has a first chamber  16  and a second chamber  18 . The upper, first chamber  16  can be inflated to the side of the chest of a vehicle occupant. The lower, second chamber  18  extends to the side of the pelvic area of the occupant. The chambers  16 ,  18  are completely separated from each other here by a separating seam  20 . At the free right-hand end of the separating seam, in addition a reinforcement  40  is provided, which prevents a tearing of the separating seam  20  during the inflation process. The two chambers  16 ,  18  have a different internal pressure in the inflated state of the gas bag  12 . In particular, the internal pressure in the first chamber  16  is higher than in the second chamber  18 , the pressure difference being able to amount to more than 1 bar.  
      A pocket is arranged on the first chamber  16  of the gas bag  12  and forms the mounting opening  22  for receiving the gas distributor housing  24  or the gas generator  14 , respectively. The gas generator  14  is securely connected with the pocket. The wall of the pocket has, in addition, a wall section  42  which lies opposite the separating seam  20  or the reinforcement  40  and is provided with holes  50  which make possible a secure connection of the gas bag  12  with the gas generator  14  or the gas distributor housing  24 .  
      The gas distributor housing  24  illustrated in FIGS.  3  to  8  comprises a flattened diffusor section  26  and a fastening section  28  lying opposite the diffusor section  26 . The diffusor section  26  of the gas distributor housing  24  has gas passage openings  36 , via which the gas flowing out from outlet openings, not illustrated, on the gas generator  14  is supplied to the chambers  16 ,  18  in the gas bag  12 . The gas passage openings associated with the respective chambers  16 ,  18  can have a different free overall cross-section, in order to ensure a different filling of the chambers  16 ,  18  and to produce a pressure difference. For this, the separating seam  20  with its reinforcement  40  lies in the operating state of the gas bag module  10  closely against the flattened diffusor section  26  of the gas distributor housing  24 , whereby a passage of gas from the chamber  18  over into the chamber  16  or vice versa is prevented. The reinforcement  40  arranged at the end of the separating seam  20  lying against the diffusor section  26  also prevents a tearing of the separating seam  20  during the inflation process or during the impact of a vehicle occupant onto the gas bag  12 . At its free ends, the gas distributor housing  24  is narrowed ( FIG. 5 ) and surrounds the gas generator  14  (not shown) in the manner of a tube clip, so that the gas generator  14  is held securely in the gas distributor housing  24 . On the other hand, the internal diameter of the gas distributor housing is greater in its central section than the external diameter of the gas generator  14 . This means that the inner wall of the gas distributor housing is spaced apart from the gas generator  14 , so that a free flow space results for the gas emerging from the gas generator  14  ( FIGS. 2 and 3 ).  
      The fastening section  28  is formed from two plates  30  lying against each other, which together form a flat fastening tongue  30  projecting radially from the gas distributor housing  24  and extending along the housing. In the fastening tongue  30 , fastening points  32  are provided, the function of which is explained further below.  
      The gas distributor housing  24  is inserted into the mounting opening  22  of the gas bag  12  so that the fastening points  32  in the fastening tongue  30  correspond to the holes  50  in the wall section  42  of the gas bag  12  ( FIG. 9 ). A strip  44  which has a U-shaped cross-sectional profile ( FIG. 3 ) is placed from the exterior onto the fastening tongue  30  and onto the wall section  42  of the gas bag  12  adjoining thereto. The strip  44  is illustrated in detail in FIGS.  11  to  14 . The U-shaped strip  44  has two arms  45  lying opposite each other with fastening points  48  arranged congruently in the arms  45 . In addition, the strip has slit-shaped perforations  46  in the fold connecting the two arms  45 . The perforations  46  facilitate the mounting of the strip  44  on the fastening tongue  30  and the wall section  42  of the gas bag  12 . The strip  44  has, in addition, fastening holes  52  by means of which the gas bag module  10  can be securely connected with the vehicle, for example with the back rest of a vehicle seat, which is not illustrated. The fastening holes  52  are arranged here in angled sections which are formed on the ends of the strip  44  and project from one of the arms  45 , so that the strip  44  is spaced apart from the supporting part on the vehicle.  
      The fastening tongue  30  and the wall section  42  of the gas bag  12  are clamped between the free arms  45  of the U-shaped strip  44 . As can be seen from  FIGS. 9 and 10 , through the application of the U-shaped strip onto the fastening tongue  30  and the wall section  42  in the direction of the arrow A, a slack which is present on the gas bag is eliminated and the separating seam  20  is drawn in the direction of the arrow B onto the diffusor section  26  of the gas distributor housing  24 . The separating seam  20  therefore, after the installation of the strip  44 , lies with its free end or with the reinforcement  40  closely against the diffusor section  26 , whereby a gas exchange between the chambers  16  and  18  is efficiently prevented.  
      The application of the strip  44  onto the fastening tongue  30  and the wall section  42  takes place such that the strip  44  is put in place with opened-out arms  45  in arrow direction A and then the arms are bent up onto the fastening tongue  30  and the wall section  42  of the gas bag  12 . The fastening points  48  of the strip  44  correspond to the fastening points  32  in the fastening tongue  30  and the holes  50  in the wall section  42  of the gas bag  12 .  
      As an alternative to the embodiment illustrated here, the strip  44  can also consist of two separate strips which then undertake the function of the arms  45 . Also in this embodiment, by the elimination of the slack on the gas bag a tension is exerted onto the separating seam  20 , which thereby lies closely against the diffusor section  26  and separates the chambers  16 ,  18  reliably from each other.  
      For the installation of the gas bag module  10 , firstly the gas generator  14  with the gas distributor housing  24  is introduced into the mounting opening  22  of the gas bag  12  or the chamber  16 , so that the fastening tongue  30  of the gas distributor housing  24  adjoins the wall section  42  of the mounting opening  22  or of the gas bag  12 . As illustrated in  FIG. 2 , the mounting opening is constructed to be so great that a comfortable introduction of the gas generator  14  and of the gas distributor housing  24  is possible and the separating seam  20  merely lies loosely against the flattened diffusor section  26  or a play is present between separating seam  20  and diffusor section  26  ( FIG. 2 ).  
      The slack on the gas bag  12  present after the introduction of the gas generator  14  and of the gas distributor housing  24  into the mounting opening  22  is eliminated in that the U-shaped fastening strip  44  is pushed or bent from the exterior onto the fastening tongue  30  and the wall section  42  of the gas bag  12  adjoining thereto. Through this application of the strip  44 , the wall section  42  is pressed closely against the fastening tongue  30  and the adjoining parts of the gas distributor housing  24  and is clamped between the arms  45  of the strip  44 . At the same time, through this process, the distance between the separating seam  20  and the diffusor section  26  is shortened and the separating seam  20  is drawn onto the diffusor section  26  so that it lies closely against it ( FIG. 3 ). By means of the fastening points  32  in the fastening tongue  30  and the fastening points  48  in the strip  44 , the gas bag  12  is fixed in this position, for example by rivets or screws. The further fastening of the gas bag module  10  on the vehicle can take place by the fastening points  52  provided on the strip  44 .  
      The invention therefore ensures an easier installation, able to be automated, of the gas generator  14  in the gas bag module  10  with, at the same time, a tight separation of the chambers  16 ,  18  in the gas bag  12 .