Abstract:
The invention relates to an airbag module for a safety system for vehicle passengers, comprising an airbag, a gas generator ( 23 ) and a diffuser ( 10 ) with a dome section ( 11 ) and at least one retaining section which maintains the airbag in a compressed manner. Said retaining section comprises at least one securing opening in which at least one securing device, in particular a securing bolt, is received. Said securing opening ( 13 ) is arranged below the dome section ( 11 ).

Description:
RELATED APPLICATIONS 
       [0001]    This application corresponds to PCT/EP2015/001990 filed Oct. 9, 2015, which claims the benefit of German Application No. 20 2014 008 432.7 filed Oct. 23, 2014, the subject matter of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to an airbag module for a safety system for vehicle passengers, comprising an airbag, a gas generator and a diffuser including a dome section as well as a retaining section which maintains the airbag in a compressed manner, wherein the retaining section comprises securing openings in which securing devices, in particular securing bolts, are received. Apart from that, the invention relates to a diffuser for an airbag module as well as to a safety system for vehicle passengers. 
         [0003]    From DE 10 2012 004 866 A1 an airbag module for a vehicle steering wheel comprising a gas generator and a diffuser is known. The diffuser is hat-shaped and includes an inversely cup-shaped outer wall the downwardly open end of which is configured to have a flange-type expansion in the type of a hat brim. Openings in the hat brim, which are evident in  FIG. 4  of DE 10 2012 004 866 A1, serve for receiving securing bolts so that an airbag can be maintained in a compressed manner by the hat brim (or the securing flange, respectively). The airbag module according to this prior art, on the one hand, has a comparatively simple construction; on the other hand, the adaptation thereof to the specific requirements of a vehicle occupant restraint system is considered to be in need of improvement. Especially, the airbag module according to prior art requires a comparatively large space and is difficult to be adapted to varying conditions. 
       SUMMARY OF THE INVENTION 
       [0004]    It is the object of the present invention to state a further developed airbag module so as to overcome the afore-mentioned drawbacks. In particular, an airbag module, a diffuser for an airbag module and a vehicle passenger safety system are to be suggested which are adapted better to the basic conditions defined by the application. Preferably the space required is to be reduced and the adaptation to different mounting environments is to be facilitated. 
         [0005]    In accordance with the invention, this object is achieved with respect to the diffuser by the subject matter of claim  1 , with respect to the airbag module by the subject matter according to claim  10  and with respect to the safety system for vehicle passengers by the subject matter according to claim  16 . Advantageous and useful configurations of the airbag module according to the invention, of the diffuser for an airbag module and of the safety system for vehicle passengers are described in the subclaims. 
         [0006]    The afore-mentioned object is achieved especially by a diffuser for an airbag module for a vehicle passenger safety system, wherein the airbag module includes an airbag and a gas generator, the diffuser comprising a dome section as well as at least one retaining section which secures the airbag in a compressed manner, wherein the retaining section includes at least one securing device, especially a securing bolt and/or at least one securing opening in which at least one securing device, especially a securing bolt, can be received, wherein the securing opening and/or the securing device is/are arranged below the dome section. 
         [0007]    According to a first inventive idea the securing openings are arranged below the dome section. In this way, the diameter of the airbag module is reduced vis-à-vis the prior art (especially DE 10 2012 004 866 A1) in which the retaining bolts and pertinent securing openings are arranged outside the dome section. This allows to better utilize the space available. In total, the diffuser is adapted especially well to the conditions for a safely system for vehicle passengers. 
         [0008]    According to a second inventive idea (which may be combined with the first inventive idea), the diffuser has an at least two-part design, wherein a first part forms the dome section and a second part (at least in part) forms the retaining section. In this way, a modular split structure is realized so that, for example, different material combinations adapted to requirements as regards the load and the function of the airbag module can be realized. Further, the special demands, especially demands to design, by car manufacturers can be taken into account. In total, also with this inventive idea a simplified and improved adaptation to the mounting location of the airbag module is realized. 
         [0009]    By “dome section” a section of the diffuser is to be understood which is towering and in its interior forms a volume which (at least in part) is adapted to accommodate the gas generator. The dome section thus forms a cage inside of which the gas generator can be arranged and can especially oscillate. The dome section is preferably configured to be inversely cup-shaped and, resp., outwardly bulged. Similarly to DE 10 2012 004 866 A1, the retaining section (in prior art referred to as “flange-type extension  125 ”) is considered to be part of the diffuser, even if the actually air-conducting function is realized by the dome section (analogously to the “inversely cup-shaped outer wall  122 ” in prior art). 
         [0010]    By an arrangement “below” the dome section especially an arrangement in which the securing openings are arranged below the wall of the dome section is to be understood. The securing openings thus (not absolutely) need to be arranged below a volume defined by the dome section but may also be arranged inside the volume defined by the dome section. Especially preferred, the securing openings are arranged below a volume defined by the dome section (i.e. inferior of the dome section), however. In general, “below” or “bottom” refers to an opening rim of the diffuser which (in the mounted state) faces the gas generator and through which the gas generator can be introduced during assembly. When the securing device or, resp., the securing opening is projected onto a plane defined by the opening rim, the securing means or, resp., the securing opening is located inside the surface defined by the opening rim. The securing openings are preferably oval and/or elliptic and/or round and/or angled (e.g. quadrangular) in cross-section. The dome section and the retaining section can be formed by a monolithic body. Alternatively, the dome section and the retaining section may be formed by separate parts which may contact each other, however. 
         [0011]    By a two-part design of the diffuser especially a configuration in which the first part is separated from the second part by the material and/or the structure is to be understood. Preferably the first and second parts are at least in portions in contact, however. The first part and/or the second part may in turn per se be monolithic bodies, for example each of them may be formed of only one material. 
         [0012]    The dome section preferably has at least one opening, further preferred at least two openings, even further preferred a plurality of openings (for example at least five or at least ten openings) through which the gas may flow out of the gas generator so that the airbag can be inflated. The retaining section may include at least two securing openings (and/or securing devices), preferably at least three securing openings (and/or securing devices), even further preferred at least four (or at least six) securing openings (and/or securing devices). 
         [0013]    The retaining section preferably has an annular section. In the annular section the securing openings may be arranged. Alternatively or additionally, the annular section may be formed by the second part. In any case, such retaining section and, resp., annular section allows to realize safe retaining of the airbag (without requiring more space). 
         [0014]    The diffuser and/or the dome section and/or the retaining section and/or the first part and/or the second part may be made from metal and/or plastic. In a concrete embodiment, the first part is made from a first material which is different from a second material of the second part. For example, different metal alloys can be used for the first and second materials. It is also imaginable that the first material is a metal and the second material is a plastic material (or vice versa). In total, different material combinations may be realized which meet the requirements regarding the load or the function of the airbag module. Further, also specific demands in terms of design of customers can be taken into account. In total the variability is increased. 
         [0015]    The first and second parts may be positively and/or adhesively and/or non-positively connected to each other. There may be provided at least one connecting moans so as to connect the first part and the second part to each other. Such connecting means may comprise a screwed connection and/or a crimped connection and/or a clip connection. The connection basically can be realized in most different ways, especially by bending and/or clipping and/or screwing and/or welding and/or gluing and/or clamping (etc.). 
         [0016]    In a concrete embodiment the diffuser, especially the first part, has at least one securing tab. The securing tab may be bent in the mounting position. Further, the securing tab may include a seat for a securing device, especially a securing bolt. The second part may have, for connecting the first and second parts, an opening corresponding to the securing tab, especially a slit through which the securing tab can be passed. After the securing tab has been passed through, it can be bent for securing the first and second parts. Such measure can help to realize a connection of the first and second parts in an especially simple manner. 
         [0017]    The foregoing object is further achieved by an airbag module comprising a diffuser of the afore-described type. Moreover, the airbag module comprises an airbag and a gas generator. 
         [0018]    In the mounted state in a concrete embodiment only the retaining section (or the second part) is in (clamping) contact with the airbag. However, in the mounted state the airbag may also be (loosely) adjacent to the diffuser. 
         [0019]    The airbag module may comprise an airbag housing and/or a module cap and/or a generator support. Preferably the airbag is clamped between the retaining section (or second part) and the generator support. 
         [0020]    The airbag module may have an absorbing element which especially is ring-shaped at least in portions. The absorbing element may include at least one (e.g. axially extending) damping member, especially an absorbing foot. The retaining section and/or the second part and/or the annular section may have at least one opening for receiving the damping member, especially the absorbing foot. At least one section, especially an annular absorbing element section, of the absorbing element may be arranged between the gas generator and the retaining element and/or between the gas generator and the second part and/or between the gas generator and the annular section. 
         [0021]    Such measures will enables the gas generator, in an efficient and constructively simple manner, to be utilized as a vibration damping mass. In particular, a compact and simple solution Is suggested for such application. 
         [0022]    The retaining section and/or the annular section and/or the second part can be arranged below the gas generator. Especially the gas generator can be arranged between the retaining section and the dome section. This, too, helps to further improve the compact design of the airbag module. 
         [0023]    The securing holes may be arranged outside a gas generator circumference (when viewed from above). Preferably, the securing holes are arranged inside the gas generator circumference, however. This, too, helps to further improve the compact arrangement. 
         [0024]    The foregoing object is further achieved by a safety system for vehicle passengers comprising a diffuser and, resp., an airbag module of the afore-described type. The foregoing object is further achieved by a steering wheel and/or motor vehicle comprising a diffuser and/or an airbag module and/or a safety system for vehicle passengers of the afore-described type. 
         [0025]    The diffuser and, resp., the airbag module and, resp., the vehicle passenger safety system can be adapted to be mounted in a steering wheel or can be mounted in a steering wheel. 
         [0026]    Basically, a design of the airbag module can be realized with an absorbing element, wherein the gas generator is supported preferably in an oscillating manner inside the diffuser, or without an absorbing element (wherein the gas generator is arranged to be preferably fixed in the diffuser). The gas generator may be secured directly to the retaining section and/or the annular section and/or the first part or via an absorbing element. Alternatively, the gas generator may be secured to the dome section of the diffuser. 
         [0027]    The airbag can be designed in a dimensionally stable manner by means of heat treatment wherein the following sequences of method steps for mounting the airbag module can be realized: 
         [0028]    In a first possible arrangement, the generator support can be secured to a module support. The module support is a component of the airbag module which is adapted to be coupled to an airbag module seat, especially to a steering wheel. Such module support is also referred to as “generator support”. 
         [0029]    In the first arrangement, furthermore an absorbing element may be provided, i.e. a resilient component, by which the gas generator can be supported in an oscillating manner. The absorbing element can be configured generally of silicone with or without any further components (e.g. metal inserts). 
         [0030]    The assembly can be carried out in the following order. At first the gas generator is arranged on the absorbing element then the absorbing element is arranged on the module support and then the diffuser is arranged on the module support. An airbag assembly may be carried out in the following order. At first the airbag is folded, then an optional heat treatment is performed, then the airbag is inserted in the module cap, then the diffuser is inserted in the airbag. After that, the module cap and the module support are connected and finally the diffuser is secured to the module support. The airbag assembly may also be carried out in the following alternative sequence. At first the dome section (the first part) is inserted in the airbag, then the airbag is folded, then an optional heat treatment is carried out, then the dome section or, resp., the first part is inserted in the module cap together with the airbag, then the dome section (the first part) is connected to the retaining section (the second part), then the diffuser and the module support are connected to each other. For the optional heat treatment of the airbag it is important that the gas generator is not mounted before the heat treatment. In the case of the absorbing element this might be possible, if it is heat-resistant. 
         [0031]    A second possible arrangement differs as to the sequence of assembly of the gas generator, the absorbing element and the diffuser from the first arrangement. At first the absorbing element is mounted to the module support, then the gas generator is mounted on the absorbing element and finally the diffuser is mounted on the module support. 
         [0032]    A third possible arrangement differs from the first arrangement in that no absorbing element is provided. The gas generator is first secured to the module support, then the diffuser is secured to the module support. The sequence of the airbag assembly corresponds to that of the first arrangement 
         [0033]    In a fourth arrangement, again an absorbing element is provided. In contrast to the first arrangement, however, the generator support is secured to the dome section (first part). The gas generator is first secured to the absorber, then the absorber is secured to the dome section (first part), then the dome section (the first part) is secured to the retaining section (second part) and finally the diffuser (the dome section and the retaining section or, resp., the first part and the second part) is secured to the module support. The sequence of the airbag assembly may correspond to that of the first arrangement. 
         [0034]    In a fifth arrangement, the gas generator is equally (just as in the fourth arrangement) secured to the dome section (or the first part). However, an absorbing element is provided. The assembly can be carried out in the following order. At first the absorbing element is mounted to the dome section or the first part, then the gas generator is mounted to the absorbing element, after that the dome section or the first part is mounted to the retaining section or the second part, and finally the diffuser (comprising the dome section and the retaining section or, resp., the first part and the second part) is mounted to the module support. The airbag assembly may be carried out corresponding to the first arrangement 
         [0035]    In a sixth arrangement, the gas generator may be secured to the retaining section or the second part. An absorbing element is provided. The assembly may be carried out in the following order. At first the gas generator is secured to the absorbing element then the absorbing element is secured to the retaining section or, resp., the second part, then the dome section or the first part is secured to the retaining section or the second part, then the diffuser (comprising the dome section and the retaining section or, resp., the first part and the second part) is secured to the module support. The airbag assembly may be carried out corresponding to the first arrangement. 
         [0036]    A seventh arrangement differs from the sixth arrangement by the order of assembly which may be carried out as follows. At first the absorbing element is secured to the retaining section or the second part, then the gas generator is secured to the absorbing element, then the dome section or the first part is secured to the retaining section or the second part and finally the diffuser (comprising the dome section and the retaining section or, resp., the first part and the second part) is secured to the module support. The airbag assembly may be carried out just as in the first arrangement. 
         [0037]    An eighth arrangement differs from the seventh arrangement by the fact that no absorbing element is provided. The mounting step for securing the absorber to the retaining section or, resp., the second part is thus omitted. Otherwise the assembly is carried out just as in the seventh arrangement. The airbag assembly, too, may be carried out corresponding to the seventh and, resp., first arrangement. 
     
    
     
         [0038]    Hereinafter the invention shall be illustrated in detail by way of embodiments with reference to the enclosed schematic figures, wherein: 
           [0039]      FIG. 1 : shows a first embodiment of the diffuser according to the invention in a first schematic oblique view; 
           [0040]      FIG. 2 : shows the diffuser according to  FIG. 1  in a second oblique view; 
           [0041]      FIG. 3 : shows the diffuser according to  FIGS. 1 and 2  in an exploded view; 
           [0042]      FIG. 4 : shows components of an embodiment of the airbag module in a schematic, partly cut oblique view; 
           [0043]      FIG. 5 : shows components of an embodiment of the airbag module according to the invention in a first schematic exploded view; and 
           [0044]      FIG. 6 : shows a second schematic exploded view of the embodiment according to  FIG. 5 . 
       
    
    
     DESCRIPTION 
       [0045]    Hereinafter like reference numerals will be used for like and equally acting parts. 
         [0046]      FIG. 1  shows a diffuser  10  comprising a first part  11  as well as a second part  12 . In securing openings  13  (of  FIG. 3 ) securing bolts  14  are arranged. Concretely, three securing bolts  14  are provided, but also a different number of securing bolts may be provided. 
         [0047]    The first part  11  includes (three) tabs  15  (cf.  FIGS. 2 and 3 ) which in the mounted state penetrate silts  16  (cf.  FIG. 3 ) and are bent for securing the first and second parts to each other (cf.  FIG. 2 ). 
         [0048]    The tabs  15  and slits  16 , resp., are arranged to face the securing bolts  14  in a radial direction and include seats  17  in which the securing bolts  14  can be received. In this way, an additional securing of the parts  11 ,  12  is achieved in a simple manner. 
         [0049]    The first part  11  at the same time forms a dome section  11  and acts as a diffuser. For this purpose, plural flow orifices  18  are provided through which the gas for inflating an airbag (not shown) can flow. The dome section  11  is domed and has a cylindrical section  19  as well as a tapering section  20  adjacent to the cylindrical section  19 . Both in the cylindrical section  19  and in the tapering section  20  flow orifices  18  are provided. The flow orifices in the concrete case have either a circular cross-section (in the cylindrical section  19 ) or a semi-elliptic cross-section (in the tapering section  20 ). The cross-sections may also have different geometries, however. 
         [0050]    The second pad  12  is arranged below a rim  21  of the first part. Furthermore, the second part has an annular shape. An underside  22  (cf.  FIG. 2 ) of the second part  12  clamps the airbag (not shown) (e.g. by interaction with the module support which is not shown either) so that the airbag is retained. Inside the diffuser  10  a gas generator (not shown) may be arranged. 
         [0051]    The securing bolts  14  serve for mounting the diffuser  10  as well as for manufacturing the clamping connection between the underside  22  and an adjacent counter-piece, especially a module support. 
         [0052]      FIG. 4  shows components of an airbag module according to an embodiment of the invention, wherein especially the first part  11  differs from the first part  11  according to  FIGS. 1-3 . Furthermore, in  FIG. 4  a gas generator  23  is evident which is arranged inside the diffuser  10 . Between the gas generator  23  and the second part  12  moreover an absorbing element  24  including absorbing feet  25  is provided so that the gas generator  23  is supported in an oscillating manner. The absorbing feet  25  are received in a generator support or module support (not shown). Further, also in  FIG. 4  tabs  15  serving for connecting the first part  11  and the second part  12  (together with silts not visible in detail) are indicated. 
         [0053]    A cross-section of the second part  12  according to  FIG. 4  is S-shaped. In an (annular) recess  26  the securing openings  13  are provided. 
         [0054]    Moreover, the second part  12  comprises openings  27  (equally in the annular recess  26 ) for receiving the absorbing feet  25 . The slits  16  are also arranged in the (annular) recess  26 . 
         [0055]    Furthermore, the recess  26  is raised vis-à-vis a (lower) rim  28  of the second part  12  so that a bearing surface (clamping surface) is defined by the rim  28 . Between the rim  28  and a facing part (especially the module support) the airbag (not shown) is maintained in a compressed manner. 
         [0056]    In the embodiment according to  FIG. 4  (just as in the embodiment according to  FIGS. 1-3 ), the securing openings  13  as well as the securing bolts  14  are arranged below the first part  11  and, resp., the dome section  11 . 
         [0057]      FIGS. 5 and 6  illustrate a schematic exploded view of components of another embodiment of the airbag module. In contrast to the embodiments according to  FIGS. 1-4 , in the embodiment according to  FIGS. 5 and 6  the securing openings  13  as well as the dedicated securing bolts  14  are not arranged below the first part  11  or, resp., the dome section  11 , but outside a projection of the first part  11  onto the plane in which the securing openings  13  are provided. The two-part design of the embodiments according to  FIGS. 5-6  of the diffuser  10  corresponds to the two-part design of the embodiments according to  FIGS. 1-4 , however. 
         [0058]    The second part  12  does not take a circular ring shape, however (as in the embodiment according to  FIGS. 1-3  and also  FIG. 4 ), but has an (approximately) triangular outer circumference, with the corners of the triangular outer circumference being rounded. A central opening  29  of the second part  12  takes a circular shape. In total the second part forms a ring. 
         [0059]    The absorbing element shown in  FIGS. 4-6  is made from elastic material, especially silicone. Reinforcing inserts (for example made from metal) may be provided. 
         [0060]    In general, in all embodiments the second part  12  is arranged between the airbag (not shown) and the first part  11 . The airbag thus is in (clamping) contact only with the second part  12  but not with the first part  11 . 
         [0061]    Basically, it is not excluded, however, that also the first part  11  (e.g. the tabs  15  thereof) is in contact with the airbag. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           10  diffuser 
           11  first part, dome section 
           12  second part, retaining section 
           13  securing opening 
           14  securing bolt 
           15  tab 
           16  slit 
           17  seat 
           18  flow orifice 
           19  cylindrical section 
           20  tapering section 
           21  rim 
           22  underside 
           23  gas generator 
           24  absorbing element 
           24  absorbing foot 
           26  recess 
           27  opening 
           28  rim 
           29  opening