Abstract:
An airbag for a motor vehicle, having a housing and at least one restraining element, which has at least one receptacle space for a gaseous medium, in particular air, and which can be moved, in the case of an accident-induced application of force to the motor vehicle, into a restraining position by the flowing of medium into the receptacle space from a storage position within the housing. At least one wall of the housing has at least one inflow opening for the medium.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to an airbag for a motor vehicle. 
     Such airbags are known and comprise an inflatable volume element for restraining occupants of the motor vehicle. The volume element comprises an inner space, into which a gaseous medium is introduced in order to move the volume element from a storage position into a restraint position to restrain the occupants. In order to guarantee optimum protection of occupants it is advantageous to inflate the volume element in a particularly short time. The faster it is inflated from its storage position into its restraint position the better the restraining function, as it can then take up a particularly large volume in an inner space of the motor vehicle in order to restrain the occupants. 
     Exemplary embodiments of the present invention are directed to an airbag for a motor vehicle that guarantees very good occupant protection. 
     In accordance with exemplary embodiments of the present invention an airbag for a motor vehicle comprises a housing and at least one restraint element comprising at least one receiving area for a gaseous medium, in particular air, said restraint element being movable in case of an accident-related force impact of the motor vehicle from a storage position within the housing into a restraint position through inflow of the medium into the receiving area. This means that the restraint element in the storage position is housed at least in areas in the housing, from which it can be moved from the storage position into the restraint position, in which the restraint element takes up a particularly large volume in an inner space of the motor vehicle in order to thus guarantee a very good restraint of occupants in case of an accident. 
     If at least one wall of the housing comprises at least one inflow opening for the medium, through which the medium can flow into the receiving area of the restraint element, the restraint element can thereby be moved particularly quickly, i.e., in a particularly short time, from its storage position into its restraint position. This means that the restraint element, in case of an accident, can take up a particularly large space or a particularly large volume in the inner space of the motor vehicle in order to protect occupants from collision with hard components causing injury. This has a particularly good effect upon occupant protection in the motor vehicle. The probability of the occupants suffering serious injuries is thus lower. 
     The restraint element can thereby be designed as a large, cohesive air sack that can be inflated by medium flowing into the receiving area for movement from the storage position into the restraint position. The medium can be actively blown into the receiving area, for example, by means of a gas generator. Alternatively, the medium can be sucked into the receiving area through the airbag unfolding upon movement from the storage position into the receiving position. 
     In addition, the restraint element can be formed by a lattice-like supporting structure, which is optionally provided with a shell at least in areas, whereby the receiving area is formed. The lattice-like supporting structure is thereby formed, for example, from a plurality of tube elements that also have a respective further receiving area, into which a medium can flow, wherein the medium is actively introduced, in particular blown, for example by means of a gas generator, into the respective further receiving area of the tube elements. Through the inflation of the tube elements the lattice-like supporting structure unfolds from the storage position into the restraint position and takes up a particularly large volume in the inner space of the motor vehicle. A so-called lattice-like bag with this supporting structure has the advantage that the receiving areas of the tube elements in sum have a smaller total volume to be inflated than the whole supporting structure ultimately takes up in the inner space. This lattice-like bag can thus take up a particularly high volume in the inner space, wherein a relatively small volume must be actively inflated. The receiving area of the airbag, formed by the supporting structure and possibly the shell, is thereby likewise filled with a gaseous medium, in particular ambient air, in order to achieve a good supporting effect of the lattice-like bag. Through the inflow opening in the wall of the housing the medium for this receiving area can flow particularly well and particularly rapidly into the receiving area of the restraint element formed by the supporting structure and optionally the shell, wherein this restraint element can likewise be moved particularly rapidly, i.e., in a short time, from the storage position into the restraint position. This is also particularly beneficial for occupant protection as the lattice-like bag can then prevent contact of the occupants with solid components that may cause injury in many cases. Through the inflow opening in the wall a possible under-pressure in the restraint element or in the receiving area, which could impede unfolding of the restraint element and thus lengthen an inflation time, can be prevented or at least reduced. 
     In an advantageous embodiment of the invention the airbag comprises at least one valve mechanism, by means of which a through-flow of the medium through the inflow opening can be adjusted. The valve mechanism preferably comprises at least one passage position exposing the inflow opening at least in areas, in which passage position the medium can flow into the receiving area. Likewise, the valve mechanism preferably has a closed position closing the inflow opening at least in areas, in which closed position an outflow of the medium from the receiving area is at least substantially prevented. Thus, the valve mechanism facilitates a particularly rapid movement of the restraint element from the storage position into the restraint position while also providing a very long useful life of the restraint element. 
     If, in case of an accident, an occupant comes into contact with the restraint element the receiving area is compressed, which causes or would cause initially an outflow of the medium from the receiving area. Due to the fact that the valve mechanism at least substantially prevents such an outflow in the closed position, the restraint element offers a certain useful life that depends upon a cross-section of the inflow opening that is opened or closed by the valve mechanism. The occupant can thus be protected in case of an accident and accelerations causing injuries can be reduced, as the medium can flow more slowly out of the receiving area than it can or could flow into the receiving area in case of movement of the restraint element into the restraint position. The inflow opening can also optionally be closed by the valve mechanism to such an extent that the medium can at least virtually no longer flow from the receiving area. It is understood that in case of a large cross-section of the inflow opening exposed by the valve mechanism more air can flow out of the receiving area. This results in a shorter useful life than in a case in which the valve mechanism exposes a smaller cross-section of the inflow opening. This results in a longer useful life of the restraint element. 
     The valve mechanism comprises for example at least one flap element, by means of which the inflow opening can be at least partially exposed or closed. The flap element is formed for example at least substantially as a film, as a textile layer and/or at least substantially from plastic. If the flap element exposes the inflow opening in the passage position it closes it at least in areas in the closed position, whereby it is supported for example on the wall of the housing delimiting the inflow opening. A failure of the flap element is thereby avoided. 
     It should be noted at this point that a ventilation, i.e., an inflow of the medium into the receiving area and possibly a valve mechanism, by means of which the through-flow of the medium through the inflow opening can be adjusted, is realized particularly in case of airbags without housing in such a way that at least one such inflow opening is integrated into a textile layer as a fabric of the airbag and thus directly into the restraint element, thus for example into the large cohesive airbag or the supporting structure or the shell thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       Further advantages, features and details of the invention follow from the following description of a plurality of preferred embodiments and by reference to the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned in the following description of the drawings and/or shown solely in the drawings can be used not only in the respectively indicated combination but also in other combinations or alone without going outside of the scope of the invention. The drawings show: 
         FIG. 1  a schematic cross-sectional view of an airbag for a motor vehicle with a housing, wherein walls of the housing comprise inflow openings for a gaseous medium; 
         FIG. 2  in a cut-out, a schematic and perspective cross-sectional view of a housing of an alternative embodiment of an airbag according to  FIG. 1 ; 
         FIG. 3  in a cut-out, a schematic and perspective cross-sectional view of a further embodiment of a housing according to  FIG. 2 ; 
         FIG. 4  in a cut-out, a schematic cross-sectional view of a further embodiment of an airbag according to  FIG. 1 ; 
         FIG. 5  a schematic and perspective view of a housing for an airbag according to  FIGS. 2 and 3 ; 
         FIG. 6  in a cut-out, a schematic and perspective view of a further embodiment of an airbag according to  FIGS. 1 and 4  with the housing according to  FIG. 5 ; and 
         FIG. 7  in a cut-out, a schematic and perspective view of a further embodiment of an airbag according to  FIGS. 1 ,  4  and  6 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an airbag  10  which comprises a housing  12  and a restraint element  14 . The restraint element  14  is thereby shown in  FIG. 1  in a restraint position, in which it takes up a very large volume in an inner space of a motor vehicle, whereby the restraint element  14  can restrain occupants particularly well and thus protect them in most cases from impact against components. The restraint element  14  can thereby be moved from a storage position into the restraint position shown in  FIG. 1 . In the storage position the restraint element  14  is received in the housing  12 . In order to ensure particularly good occupant protection the restraint element  14  can be moved particularly rapidly, i.e., in a particularly short time, from the storage position into the restraint position. In this connection the restraint element  14  comprises a receiving area  16  that is delimited in areas through the restraint element  14  and in areas through the housing  12 . Ambient air can flow into the receiving area  16  for movement of the restraint element  14  from the storage position into the restraint position. In order to ensure that a particularly large amount of ambient air can flow into the receiving area  16  in a particularly short time, both side walls  18  and  20  and also a bottom  22  of the housing  12  comprise inflow openings  24 ,  26  and  28 , through which the ambient air can flow according to direction arrows  30 ,  32 ,  34  and  36  into the receiving area  16 . 
     In order to guarantee this inflow the airbag  10  comprises valve mechanisms  38 ,  40  and  42  with respective valve flaps  44 ,  46 ,  48  and  50 . The valve mechanisms  38 ,  40  and  42  have a closed position, in which an outflow of the ambient air contrary to the direction arrows  30 ,  32 ,  34  and  36  is at least substantially prevented. Likewise they have an open position shown in  FIG. 1 , in which the inflow of air according to the direction arrows  30 ,  32 ,  34  and  36  is facilitated. 
     The valve mechanisms  38 ,  40  and  42  thus facilitate not only an inflow of a particularly large quantity of ambient air in a particularly short time into the receiving area  16  but also facilitate a long and advantageous useful life of the restraint element  14 . This occurs because when an occupant impacts against the restraint element  10  the air in the receiving area  16  cannot flow or cannot flow unhindered out of the receiving area  16  contrary to the direction arrows  30 ,  32 ,  34  and  36 . Unhindered outflow of the ambient air via the inflow openings  24 ,  26  and  28  is at least substantially prevented through the valve flaps  44 ,  46 ,  48  and  50  in the closed position. 
     As can be seen from  FIG. 1 , the valve flaps  44 ,  46 ,  48  and  50  lift in the open position from the side walls  24  and  26  and the bottom  22 . If an inflow process of the ambient air into the receiving area has ended due to the unfolding restraint element  14  the valve flaps  44 ,  46 ,  48  and  50  again lie against the side walls  18  and  20  and the bottom  22 , as the valve flaps  44 ,  46 ,  48 ,  50  are, for example, elastically formed and seek without force a state in which they lie against the side walls  24  and  26  and the bottom  22  and thus cover and close the inflow openings  24 ,  26  and  28 . If an occupant contacts the restraint element  14  the inner pressure in the receiving area  16  increases and the valve flaps  44 ,  46 ,  48  and  50  are pressed even more greatly against the side walls  18  and  20  and the bottom  22 . A controlled and defined outflow of the ambient air out of the receiving area  16 , wherein a certain volume flow of the ambient air can flow out, is optionally desired in order to remove accelerations acting on the occupants. Such a volume flow is realized, for example, in that the inlet flows  24 ,  26  and  28  are only covered in areas by the valve flaps  44 ,  46 ,  48 ,  50  and these thus expose a certain cross-section of the inflow openings  24 ,  26  and  28 . It is also possible to allow such an outflow of the ambient air out of the receiving area  16  through other openings, valve mechanisms or similar which are integrated for example into the restraint element  16 . 
       FIG. 2  shows an alternative embodiment of the housing  12  which is formed from a metal grid and thus provides a plurality of inflow openings for the ambient air. A valve function for the plurality of inflow openings according to the valve mechanisms  38 ,  40  and  42  is provided, for example, by valve flaps which are formed from a film or films, fabric or fabrics or similar. It is also possible to form the housing  12  as a grill element or other perforated material. Plastic, sheet metal or other materials may be used 
       FIG. 3  shows a further embodiment of the housing  12  with the side walls  18  and  20  and the bottom  22 , wherein the side wall  20  comprises three inflow openings  26 ,  26 ′ and  26 ″. The bottom  22  comprises four inflow openings  26 ′″,  26 ″″,  26 ′″″ and  26 ″″″. A particularly large amount of ambient air can thereby flow according to direction arrows  32  into the receiving area  16 . 
       FIG. 4  shows a further embodiment of the airbag  10 , wherein the airbag  10  comprises gas generators  52  and  54 . The restraint element  14  comprising the receiving area  16  is formed as a so-called lattice-like bag which comprises a lattice-like-like supporting structure that is provided with a shell formed as fabric. In other words, the receiving area  16  is delimited by the supporting structure and by the shell as well as by the housing  12 . The lattice-like supporting structure is in turn formed from a plurality of tube elements, which respectively comprise a receiving area, into which a gaseous medium is to flow or be blown in order to thus inflate the tube elements and thus the lattice-like supporting structure, whereby the restraint element  14  can be unfolded from the storage position received in the housing  12  into the restraint position shown in  FIG. 4 . For particularly rapid inflation of the tube elements, and thus of the supporting structure, the gas generator  52  blows the gaseous medium into the further receiving areas of the tube elements. In order to further support the unfolding of the restraint element  14  the gas generator  54  blows a gaseous medium via an inflow opening  24 ′ of the side wall  20  of the housing  12  into the receiving area  16 . 
       FIG. 5  shows a further embodiment of the housing  12  that comprises the side walls  18  and  20 , the bottom  22  and end walls  56  and  58 . As can be seen from the drawing, a plurality of inflow openings  24  are provided respectively in the side walls  18  and  20  and in the end wall  56 , via which the gaseous medium, in particular ambient air, can flow into the receiving area  16  according to direction arrows  32 , whereby this can be seen from  FIG. 6 . 
       FIG. 6  thereby shows a further embodiment of the airbag  10  with the housing  12  according to  FIG. 5 . As can be seen in  FIG. 6 , the bottom  22  of the housing  12  also comprises a plurality of inflow openings  24 , through which ambient air can flow into the receiving area  16  upon movement of the restraint element  14  from the storage position into the restraint position. 
       FIG. 7  shows a further embodiment of the airbag  10  that comprises the housing  12  and the restraint element  14 . Furthermore, the airbag  10  according to  FIG. 4  comprises a gas generator  60 , by means of which a gaseous medium can be blown both into the receiving area  16  and also into the tube elements described in connection with the airbag according to  FIG. 4  in order to inflate the supporting structure which is in particular lattice-like. 
     It is understood that the indications concerning the restraint element  14  according to  FIG. 4  also apply similarly to the airbags  10  according to  FIG. 1 ,  FIG. 6  and  FIG. 7  and can be transferred and applied to their respective restraint elements  14 . 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.