Abstract:
The invention relates to a gas flow distributor for a lateral airbag module. The distributor is used to distribute a gas flow leaving a gas generator by the outflow openings thereof, in a targeted manner, in a gas bag which is to be inflated by the gas generator. According to an embodiment, the gas flow distributor is formed by a dimensionally stable receiving element surrounding outflow openings of the gas generator.

Description:
BACKGROUND 
     The invention relates to a gas flow distributor for a lateral airbag module. 
     A lateral airbag module serves in the event of a crash to protect a vehicle occupant from colliding with lateral parts of the vehicle body, and is generally arranged in a vehicle door or laterally on a vehicle seat. In addition to a gas bag which can be inflated in the event of a crash to protect the particular vehicle occupant, the lateral airbag module comprises a gas generator for inflating the gas bag and a housing for holding the gas generator and gas bag. In order for an airbag module to be able to deploy the best possible restraining and therefore protective function for a vehicle occupant, a targeted, defined deployment of the gas bag during the inflation by means of the gas generator is of particular importance. 
     In lateral airbag modules, it is known to direct the gas flow within the gas bag by tucks or fabric flaps provided in or on the gas bag covering and to distribute it in a defined manner within the gas bag. In this case, the gas bag is divided by the tucks or fabric flaps into different regions which are intended to ensure a defined, predeterminable gas flow during the inflation of the gas bag. 
     SUMMARY OF THE INVENTION 
     The invention is based on the problem of providing a gas flow distributor of the type mentioned at the beginning, which contributes to a targeted, defined deployment and positioning of the gas bag to be inflated by the gas generator. 
     This problem is solved according to the invention by the provision of a gas flow distributor according the embodiments described herein. 
     According to them, the gas flow distributor is formed by a dimensionally stable holder surrounding the gas generator at least in the region of its outflow openings. 
     The solution according to the invention has the advantage that the gas flow distributor has an immediate, direct influence on the gas flow emerging from the gas generator, in order to achieve a defined deployment and positioning of the gas bag to be inflated. Thus, by suitable designing of that region of the gas flow distributor which holds the gas generator, the direction of deployment of the gas bag can be defined at an early point and durably in a predetermined manner. In this connection, the opening of the covering of the airbag module can also be positively influenced. Furthermore, by directing the gas flow, the inflation behavior of the gas bag in an oop situation (out-of-position situation), in which the occupant who is to be protected is outside his normal sitting position, can be influenced in such a manner that the risk of an occupant being injured is minimized. 
     Finally, a targeted distribution of the quantity of gas or of the gas flow enables the gas flowing out of the gas generator to be guided in a defined manner into the one or other chamber of a multi-chamber gas bag. 
     The above-described effects are achieved, in particular, by the fact that the gas emerging from the outflow openings of the gas generator is initially collected, immediately after it has emerged, in the holder formed by the gas flow distributor and then is guided on in a defined manner, along a predeterminable direction, into the interior of the gas bag to be inflated. 
     The gas flow distributor consists of such a dimensionally stable material, for example metal or a diecasting, that the holder formed by the gas flow distributor is not noticeably deformed by the gas flow emerging from the gas generator. Accordingly, in contrast with a gas flow distributor which is formed by tucks, fabric flaps, flexible tubing or the like provided in the gas bag covering, according to the present invention defined conditions, which cannot be adversely affected by the gas flow, are provided for the distribution of the gas flow. However, individual sections, for example in the form of a flap, may be provided on the holder of the gas flow distributor and can be moved in a targeted manner by the gas flow in order to release an outlet opening for the gas flow. 
     The holder of the gas flow distributor is designed in particular for the insertion of a tubular gas generator which, as part of a lateral airbag module, is to be arranged in a vehicle door or on a vehicle seat. For this purpose, the gas flow distributor has a holding region which surrounds the tubular gas generator and is of tubular design, for example is of polygonal or curved design in cross section. In one preferred embodiment, the holder of the gas flow distributor is designed to let a gas flow into a gas bag to be inflated, essentially along the circumferential surface of the holder, for example in the axial direction. In such a case, the gas flow which usually emerges vertically from a gas generator does not therefore pass simply along this direction into the gas bag, but rather is deflected beforehand, namely in a direction along the circumferential surface of the gas flow distributor which surrounds the gas generator at least in the region of its outflow openings. 
     In order to let the gas flow in a defined manner into the gas bag to be inflated, the holder forming the gas flow distributor has at least one outlet opening through which gas which has flowed into the interior of the holder can emerge from the gas generator and can flow into the gas bag to be inflated. In the case of a gas flow distributor having a tubular holding region, outlet openings of this type can be provided, in particular, in the casing of the holding region. 
     In one development of the invention, the size of the outlet openings can be set in order to match them to different circumstances. 
     Furthermore, the at least one outlet opening of the gas flow distributor can be at least partially closed by a covering which is opened by the gas flow emerging from the gas generator, and, as a result, the gas can flow into the gas bag to be inflated. In this case, the outlet openings are preferably arranged and designed to conduct the gas flow emerging from a tubular gas generator in the axial direction, i.e. along the direction of extent of the gas generator. In the opened state, the covering can serve at the same time as a directing element with which gas flowing through the outlet opening of the gas flow distributor is predetermined a direction of flow when flowing into the gas bag to be inflated. 
     The gas flow distributor is preferably designed in such a manner, i.e. is matched in such a manner to the outer shape, size and outflow openings of the gas generator, that the gas flowing out of the gas generator is at least in part initially reflected against a wall of the holding region before it emerges from the gas flow distributor. This prevents the hot gases flowing out of the gas generator from coming directly into contact with the fabric or the seams of the gas bag to be inflated or with other heat-sensitive parts. Instead, first of all the gas within the holding region of the gas flow distributor is cooled before the gas flows on into the gas bag to be inflated. In addition, the velocity of the gas flow is also retarded. This enables less exacting requirements to be made of the coating of the gas bag covering. Furthermore, the influencing of the gas flow by the walls of the holding region of the gas flow distributor can also serve for directing the gas flow per se, in particular in order to permit the gas flow to be deflected in the axial direction, along the direction of extent of a tubular gas generator, when it passes through the outlet openings of the gas flow distributor. 
     The gas pressure within the holding region can be influenced by varying the volume available for the gas within the holding region of the generator support, i.e. as a function of the distance of the outer wall of the gas generator from the inner wall of the holding region of the gas flow distributor. This in turn has an effect on the distribution of the quantity of gas via the corresponding outlet openings of the holding region. The size of the outlet openings of the holding region (outlet area of the openings) determines, inter alia, the inflation velocity of the airbag and the distribution of the quantity of gas within various airbag regions, which is of importance in particular in the case of multi-chamber systems in which different internal pressures are to be produced in different chambers. 
     In addition, the velocity of the program of deployment of the airbag can also be influenced by the shape of the holding region (hollow-cylindrical or different tube shape). 
     In one development of the invention, the gas flow distributor can serve at the same time as the generator support which holds the gas generator and is connected via a connecting region to a supporting part of a motor vehicle, in particular a supporting part of a vehicle door or of a vehicle seat. 
     The connecting region of the generator support, which is arranged and designed to provide an indirect or direct connection to a supporting part of a motor vehicle, can be configured, for example as a flange which protrudes from the holding region of the generator support. In one preferred embodiment, the generator support is of single-piece design, i.e. the connecting region of the generator support is integrally formed as a single piece on the holding region thereof. 
     It is advantageous to design at least one region of the holder as an impact element, so that at least one gas-guiding duct for guiding the gas flow runs between the impact element and the gas generator. This has the advantage that the gas flow distributor immediately and directly influences the gas flow emerging from the gas generator and, by means of the design of the gas-guiding duct, the gas flowing out can be guided in a defined manner into a certain region of the gas bag to be inflated. The guiding of the gas flow enables the inflation behavior of the gas bag to be influenced in such a manner, even in an oop situation, in which the occupant to be protected is outside his normal sitting position, that the risk of an injury to the motor vehicle occupant by the deploying gas bag is reduced. Furthermore, the targeted distribution of the quantity of gas or of the gas flow of the gas flowing out of the gas generator enables the gas to be guided in a defined manner into one or more chambers of a multi-chamber gas bag or into a plurality of gas bags. In this case, the gas flow distributor according to the invention can also serve for attaching a plurality of gas bags to a gas generator. 
     The gas-guiding duct can be formed here either between the outside of the gas generator and the inside of the holder, which is designed as an impact element, or else between the outside of a region of the holder that surrounds the gas generator and the inside of the impact element. 
     In one preferred embodiment of the invention, the impact element has an essentially circular cross section and is fitted in such a manner that the gas-guiding duct essentially has a circular ring-shaped or a crescent-shaped cross section. Appropriate dimensioning of the gas-guiding duct thus enables, owing to a small flow cross section, very high gas outflow velocities and therefore a very high impulse transmission to be transmitted to the gas bag covering to be deployed. 
     The impact element is advantageously designed in such a manner that, even during plastic deformation, as may occur, for example, during the installation process or during operation of the gas generator, the function of the impact element is maintained. Thus, for example, even local or temporal high-pressure maxima of the gas flow can be compensated for without the functioning of the gas flow distributor being adversely affected. 
     The gas outlet regions of the gas-guiding ducts advantageously lead into at least one gas bag or into different gas bag chambers. When a plurality of gas bag chambers or a plurality of gas bags are used, the impact element may serve to separate two gas bag chambers from each other or may serve as a single connection between two gas bags. In this case, a separating gap running between two gas bags may run in the region of the impact element, so that communication between the gas bags is possible only via the gas-guiding duct. Furthermore, it is advantageous to brace the separating gap in a gastight manner via the impact element. 
     A lateral airbag module having a gas generator for inflating a gas bag and a gas flow distributor designed in accordance with the invention is characterized by the features of claim  39 . 
     In one preferred embodiment of this airbag module, the holding region of the gas flow distributor is arranged within the gas bag to be inflated. This permits a particularly compact construction of the airbag module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention will become clear in the following description of an exemplary embodiment with reference to the figures, in which: 
         FIG. 1  shows a perspective illustration of a gas flow distributor for holding a gas generator; 
         FIG. 2  shows a perspective rear view of the gas flow distributor from  FIG. 1 ; 
         FIG. 3  shows a first modification of the exemplary embodiment from  FIGS. 1 and 2 ; 
         FIG. 4  shows a second modification of the exemplary embodiment from  FIGS. 1 and 2 ; 
         FIG. 5  shows a rear view of the gas flow distributor from  FIG. 4 ; 
         FIG. 6  shows a perspective illustration of a further embodiment of a gas flow distributor according to the invention; 
         FIG. 7  shows an exploded drawing of the gas flow distributor from  FIG. 6 ; 
         FIG. 8  shows a perspective illustration of a further embodiment of a gas flow distributor according to the invention; 
         FIG. 9  shows a plan view of the gas flow distributor from  FIG. 8 ; 
         FIG. 10  shows a lateral view of the gas flow distributor from  FIGS. 8 and 9 ; 
         FIG. 11  shows a cross section through the gas flow distributor from  FIGS. 8 ,  9  and  10 ; 
         FIG. 12  shows a perspective illustration of a further embodiment of a gas flow distributor according to the invention; 
         FIG. 13  shows a lateral view of the gas flow distributor from  FIG. 12  with the gas generator inserted; and 
         FIG. 14  shows a cross section through the gas flow distributor from  FIGS. 12 and 13 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective illustration of a gas flow distributor in the form of a generator support  1  for holding a gas generator. The generator support  1  forms part of a lateral airbag module and can support a gas generator with which a gas bag can be inflated in a sensor-controlled manner to protect a vehicle occupant in the event of a crash. The gas bag and the gas generator are usually arranged in a module housing which has a covering which opens during the inflation of the gas bag, so that the gas bag can be deployed in the direction of the vehicle occupant to be protected. 
     The gas generator is connected via the generator support  1  either to a supporting part of the airbag module, for example the housing of the airbag module, or directly to a supporting part of the vehicle body, for example a door panel or a seat frame in the case of a lateral airbag. By this means, the gas generator is coupled via the generator support to a supporting vehicle part. 
     According to  FIG. 1 , the holding region  10  of the generator support  1  is of tubular, in particular hollow-cylindrical, configuration, so that a tubular gas generator arranged within the holding region  10  is surrounded by the holding region  10 . The holding region  10  forms in cross section a slotted ring with a plate  21  and  22  protruding radially in each case from its ends placed on both sides of the slot. 
     The hollow-cylindrical holding region  10  has two open cover surfaces  11 ,  12  on its end sides, the cover surfaces permitting the introduction of a gas generator into the holding region  10  by said slot expanding, and two large recesses  16 ,  17  in its casing surface, the recesses serving to reduce the weight of the generator support  1 . Next to the one large recess  16 , an outlet opening  18  is additionally provided in the casing surface, said outlet opening being partially covered by an elevation  13  of the casing surface, which forms the outer wall  10   a  of the holding region, and said outlet opening being situated above the outflow openings of the gas generator leading into the generator support  1 , when the gas generator is introduced. The elevation  13  serves as guiding element with which the direction of the gas flow emerging from the outlet opening  18  can be influenced. 
     Gases which have flowed from a gas generator into the interior of the holding region  10  can pass on through the last-mentioned outlet opening  18  into the gas bag to be inflated. For this purpose, the holding region  10  of the generator support  1  is preferably arranged together with the gas generator arranged in it within the gas bag, which is to be inflated, of the airbag module. 
     The arrangement, shape and size of the outlet opening  18  of the holding region  10 , through which gas flowing from a gas generator can pass into the gas bag to be inflated, and the elevation  13  determine the direction and velocity at which the gas enters into the gas bag. 
     In the present case, the gas flow G flowing through the outlet opening  18  is directed by means of the elevation  13  along the casing surface of the receiving region  10 , in particular in the axial direction. 
     As becomes clear with reference to the rear view according to  FIG. 2 , two further outlet openings  19 a,  19 b are provided lying radially opposite each other on both sides of an elevation  13  in the casing of the holding region  10  and the above outlet opening  18 , with it being possible for a gas flow G to emerge through them along the surface of the outer wall  10   a  of the holding region  10 , specifically, in particular, in the axial direction of the longitudinally extended generator support  1 . 
     The gas generator to be held in the holding region  10  of the generator support  1  can be arranged there in particular in such a manner that gas flowing out of the outflow openings of this gas generator is directed toward the inner wall  10   b  of the holding region  10 . In this case, the outflow openings of the gas generator are preferably situated in the region of that section of the holding region  10  of the gas generator support  1  which is provided with the outlet openings  18 ,  19   a ,  19   b . The gas flowing from the gas generator into the interior of the generator support  1  is initially reflected against the inner wall  10   b  of the holding region  10  before it passes through the openings  18 ,  19   a ,  19   b , provided for this purpose, in the holding region  10  into the gas bag to be inflated. As a result, the gas flow is somewhat cooled and slowed down before it impacts against any heat-sensitive parts of the gas bag, for example the gas bag covering or seams. The risk of damage to the gas bag by hot gases can thereby be considerably reduced. 
     A connecting region  20  having fastening openings  23  is integrally formed as a single piece on the holding region  10  of the generator support  1  and can be used to connect the generator support to a supporting part of the airbag module or a motor vehicle body. The connecting region  20  is designed as a flange and comprises two plates  21 ,  22  which bear against each other and are integrally formed as a single piece on the holding region  10 . For this purpose, the holding region  10  forms in cross section a slotted ring with one of the plates  21 ,  22  integrally formed on each of its two ends. In order to stabilize the connecting region  20 , stiffening elements  25  via which the connecting region  20  is additionally connected to the holding region  10  are additionally provided. 
     The exemplary embodiment of a generator support that is illustrated in  FIG. 3  differs from the one illustrated in  FIGS. 1 and 2  merely in respect of the design of two outlet openings which are provided in the wall of the holding region  10 . Otherwise, the two exemplary embodiments correspond, and so reference is made in this regard to the details for  FIG. 1 . Components of the generator support which correspond are provided with identical reference numbers in the two figures. 
     According to  FIG. 3 , two outlet opening  14   a ,  14   b  placed next to the two large recesses  16 ,  17  are formed by the two open end sides of a duct  14  which is integrally formed as an elevation on the outer wall  10   a  of the holding region  10 . The gases G emerging through the open end sides  14   a ,  14   b  flow first of all parallel to the outer wall  10   a  of the holding region  10 , predominantly in the axial direction of the generator support  1 , and then pass into the gas bag to be inflated. 
     The generator support  1  is installed in a vehicle in such a manner that its longitudinal axis extends essentially along the vertical vehicle axis. The gas flow emerging from the gas flow distributor in the form of a generator support is therefore directed upward or downward essentially in the vertical direction through the respective outlet openings  14   a ,  14   b ,  18 ,  19   a ,  19   b.    
       FIGS. 4 and 5  illustrate a further modification of the exemplary embodiment from  FIGS. 1 and 2 , the difference residing exclusively in the design of the outlet openings through which gas which has flowed into the gas flow distributor (generator support  1 ) from a gas generator can flow on into a gas bag to be inflated. 
     According to  FIGS. 4 and 5 , an outlet opening  15  is arranged next to the large recesses  16 ,  17  in the holding region  10  of the generator support  1 , said outlet opening being partially closed by a covering in the form of tabs  150 . In this case, the recess  15  extends with slot-shaped runners along the lateral edges of the tabs  150 , so that the latter are connected only in an end section to the casing surface of the tubular holding region  10 . 
     In this case, the gas which emerges from the gas generator after the airbag module is triggered and flows, in particular, toward the inner wall  10   a  of the holding region  10  raises the tabs  150  which partially cover the outlet opening  15 , as indicated in  FIG. 5  with reference to the double arrow, so that the tabs  150  protrude obliquely from the casing surface of the tubular holding region  10 . This firstly enables the cross-sectional area of the outlet opening  15  through which the gas which has emerged from the gas generator can flow into the gas bag to be inflated to be enlarged. At the same time, after bending over outward, the tabs  150  form guiding elements which contribute to guiding the gas flow G, when it flows through the outlet opening  15 , along the casing surface of the tubular holding region  10  of the generator support  1 . In particular, the tabs  150  in this state counteract a radial and tangential outflow of the gases, so that the gas flow G has, above all, a component in the axial direction of the tubular holding region  10 . 
     The direction of flow of the gas passing through the outlet opening  15  can be influenced by varying the geometry of the outlet opening  15  and of the tabs  150  and by the specification associated therewith of the direction along which the tabs  150  are bent over outward by the pressure of the gas flow. 
       FIGS. 6 and 7  show a further embodiment of a gas flow distributor according to the invention. The gas flow distributor has a holder in the form of an impact element  3  which surrounds a tubular gas generator  6  in the region of the gas outflow openings  60  of the tubular gas generator  6 . In this case, the impact element  3  is in the form of a hose-clip-shaped holder which surrounds the tubular gas generator  6  largely without any contact. As a result, a gas-guiding duct  100  for guiding the gas flow emerging from the gas outflow openings  60  of the tubular gas generator  6  is formed between the hose-clip-shaped impact element  3  and the tubular gas generator  6 . 
     The tubular gas generator  6  is held in a fastening device  7 , which is likewise hose-clip-shaped, and can be fastened via said fastening device to a motor vehicle structure (not illustrated here). For fastening purposes, the tubular gas generator  6  is held here in a cylindrical recess  73  in the hose-clip-shaped fastening element  7 . In the region of the gas outlet openings  60  of the tubular gas generator  6 , the fastening element  7  has a cutout region  72 , so that the gas flowing from the gas outflow openings  60  is not obstructed by the hose-clip-shaped fastening element  7  from flowing out. 
     In addition, the fastening element  7  has a fastening region  70  which serves to attach the tubular gas generator  6  together with the impact element  3  to a motor vehicle structure via joining elements in the form of rivets and/or screws  401  which are guided in holes  701 ,  40 . At the fastening region  70 , an airbag can be placed between the fastening region  70  and a clamping rail  4  in such a manner that the gas-guiding device is surrounded by the airbag fabric. Tightening of the joining elements  401  causes the airbag to be tightened around the impact element and sealed or connected fixedly to the gas-guiding device and/or to a means of attaching it to the vehicle structure. 
     The impact element  3  likewise has a fastening section  30  into which rivet-shaped fastening means  401  can be guided, likewise through holes  301 , and result in the hose-clip-shaped impact element  3  being fastened to the hose-clip-shaped fastening element  7 . 
     A crescent-shaped gas-guiding duct  100  is formed between the gas generator  1  and the hose-clip-shaped impact element  3 . In this case, the gas flowing from the gas outflow opening  60  of the tubular gas generator  6  impacts initially against the hose-clip-shaped impact element  3  and is then guided in the gas-guiding duct  100  in the direction of two opposite gas outflow regions  101 ,  102 . In the embodiment illustrated here, the gas flows emerging from the two gas outlet regions  101 ,  102  emerge in directions essentially opposed to each other and along the tube axis R of the tubular gas generator. In this case, the gas-guiding duct  100  has a flow cross section which arises from the outside diameter D 2  of the hose-clip-shaped fastening element  7  and the inside diameter D 3  of the hose-clip-shaped impact element  3 . 
       FIGS. 8 to 11  show a further embodiment of the gas-guiding device according to the invention. The gas-guiding device has a holder in the form of an impact element  5  which can be arranged on a gas generator  6 . 
     The embodiment shown here integrates the impact element, which is realized separately in the embodiment of  FIGS. 8 and 9 , with a fastening element for the gas generator. The gas generator, which is designed as a tubular gas generator  6 , is surrounded by hose-clip-shaped regions  50  of the impact element  5 . The hose-clip-shaped regions  50  are situated in a region of the tubular gas generator  6  in which no gas outflow openings are provided. A further hose-clip-shaped region  51  of the impact element  5  is provided in the region of the gas outflow openings of the gas generator  6  and has a larger diameter D 5  than the hose-clip regions  50  securing the tubular gas generator  6 . This in turn forms, between the hose-clip-shaped region  51  of the impact element  5  and the tubular gas generator  6 , a gas-guiding duct  100  which leads into two mutually opposite gas outlet regions  101 ,  102 . 
     Since the two hose-clip-shaped regions  50 , which secure the tubular gas generator  6 , and also the hose-clip-shaped region  51  guiding the gas flow are formed as a single piece from a single metal sheet, they have a common “back” which lies opposite a fastening region  52  for attaching the gas-guiding device to a vehicle structure. The gas-guiding duct  100  therefore has a crescent-shaped cross section which arises from the eccentric position of the tubular gas generator  6 . 
     In the embodiment shown, the impact element  5  furthermore has a clamp  53  which keeps a gas bag opening arranged in this region open, so that a gas flow can flow unobstructed into the gas bag. 
       FIGS. 12 to 14  show a further embodiment of a gas-guiding device according to the invention, it being possible for the gas-guiding device to have in turn a holder in the form of an impact element  5  which can be arranged on a gas generator  6 . 
     The tubular gas generator  6  is surrounded and held by hose-clip-shaped regions  50  of the impact element  5 . In contrast with the embodiment shown in  FIGS. 8 to 11 , the impact element  5  here is configured in such a manner that the fastening region  52  is situated on that side of the impact element  5  which is opposite the gas-guiding duct  100 . The gas outflow openings  101 ,  102  are thereby likewise situated on that side of the gas-guiding device which is opposite the fastening region. The individual hose-clip-shaped regions  50 ,  51  completely surround the gas generator  6 . 
     In one embodiment (not illustrated here) two gas bags adjoin the impact element  3 ,  5  in such a manner that in each case at least one gas-guiding duct  100  leads into each gas bag. In this case, the impact element  3 ,  5  may also be arranged in the region of a separating gap between the two gas bags. The gas-guiding ducts formed by the impact element enable the two gas bags thus to be inflated uniformly or in a predetermined manner using a single gas generator.