Abstract:
The invention relates to an airbag arrangement in vehicles, which is preferably secured at the steering wheel ( 11 ) of the vehicle and which comprises a gas generator ( 12 ) which is secured to a generator carrier ( 14 ) and which can be ignited in the event of an accident, an inflatable gas bag ( 13 ) which is at least largely tightly connected to the latter via an opening ( 17 ), which is folded together and which can be inflated by the gas from the gas generator ( 12 ), and securing means ( 15, 16 ) for the edge ( 18 ) of the gas generator ( 12 ) surrounding the opening ( 17 ) which are attached to the vehicle, in particular at the steering wheel ( 11 ). The invention consists in that the gas generator ( 12 ) is attached in a resiliently yielding manner at least in one direction, preferably in all directions at least substantially perpendicular to the central axis ( 19 ) of the gas generator ( 12 ) or the generator carrier ( 14 ) or, respectively, of the steering column independently of the securing means ( 15, 16 ) for the gas bag ( 13 ).

Description:
BACKGROUND 
     The invention relates to an airbag arrangement in vehicles which is preferably secured to the steering wheel of the vehicle as well as to an oscillation absorber for a motor vehicle steering wheel. 
     In motor vehicle steering wheels, oscillation absorbers are often used in order to absorb low frequency oscillations of the airbag-steering wheel/steering column system. Oscillation absorbers of this kind consist substantially of additional masses which are resiliently suspended in a separately mountable frame and which have eigen-frequencies which are matched to the steering system and a compulsorily limited deflection. 
     SUMMARY OF THE INVENTION 
     The object of the invention consists in reducing the mass required for the creation of an oscillation absorber. 
     For satisfying this object the invention provides that the oscillation absorber mass is formed by all or a portion of the components of an airbag arrangement with the exception of the cover. 
     For this, in accordance with the invention and in contrast to conventional airbag modules in which the gas generator is firmly mounted, the latter is decoupled alone or together with further module parts from the gas bag holder and cover and seated in the steering wheel in a manner such that it is capable of oscillating with a limited deflection. 
     A further object of the invention consists in creating an airbag arrangement of the initially named kind which is particularly suitable for the absorption of oscillations in the steering column of motor vehicles. 
     The basic idea of the present invention is thus to be seen in that the entire airbag arrangement or a portion of it with the exception of the cover closing it off is used as an oscillation absorber mass which is in particular capable of oscillation transverse to the steering axis. The cover only should not participate in the oscillation because the steering wheel should also be closed off from the outside in the region of the airbag arrangement by a through-going, non oscillating surface. 
     Whereas in principle the gas bag holder means can also be designed as a constituent of the oscillation absorber mass, it is nevertheless preferred when only the generator carrier with the components which hold it forms the oscillation absorber mass, since otherwise sufficient oscillatory spaces would have to be made available inside the steering column for the gas bag holding means, which could lead to space difficulties. If, on the other hand, only the gas generator with the parts secured to it oscillates, then the outer dimensions of the airbag arrangement and in particular the installation indentations in the steering wheel can remain unchanged with respect to non-oscillating airbag arrangements because the oscillatory space for the generator and the components secured to it can be made available inside the airbag arrangement. 
     In so far as only the generator carrier with the components secured to it is seated in a manner such that it is capable of oscillating, the catcher prongs can be secured either to the steering wheel or at the oscillating module part, whereas on the contrary the elastic bearings are secured at the module part and the steering wheel respectively. 
     To avoid an interaction of the oscillating subsystems with the non-oscillating module constituents, the latter are brought to a definite minimum distance outside the permissible deflection. 
     Preferred embodiments of the non-oscillating parts of the airbag module include the holder basket which serves as a collision protection in the event of a failure of the airbag. 
     For an ideal cooperation of oscillating and non-oscillating constituents of the airbag module, the present invention provides for tightness during the ignition of the gas generator. A particular importance is taken on here by the ring seal which effectively avoids leakage losses during the ignition of the gas generator. 
     In order to take up axial tangential forces which arise between the gas bag holder means and the gas generator during the ignition of the gas generator special holder means are provided which determine the maximum possible, not too great distance between the gas bag holder means and the gas generator in particular during the ignition of the gas generator. 
     In accordance with the present invention the gas bag holder means can also be resiliently axially movable in order e.g. to actuate a horn switch which is arranged in the steering wheel. 
     The most important advantages of the idea of the oscillation absorber in accordance with the invention lie in the saving in weight, because additional masses can be omitted. Through the saving in weight, a lower total mass of the steering system which must be counteracted by the oscillation absorber is also present. Substantial cost savings are thus possible through the function transfer to fewer components. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in the following in an exemplary manner with reference to the drawings; in these are shown: 
     FIG. 1 a schematic, broken open perspective view of an airbag arrangement in accordance with the invention which is arranged at a vehicle steering wheel which is merely indicated, 
     FIG. 2 a view similar to that of FIG. 1, with the steering wheel however not being indicated and only the oscillating parts of the airbag arrangement being reproduced, and 
     FIG. 3 a perspective view similar to that of FIG. 1, with the steering wheel however not being indicated and only the non-oscillating parts of the airbag arrangement being reproduced. 
    
    
     DETAILED DESCRIPTION 
     In accordance with FIG. 1 a gas bag  13 , which is merely indicated purely schematically in dotted lines, is provided with a central opening  17  and a clamping edge  18  surrounding the latter. The edge  18  is clamped in between an outer ring-shaped holder sheet metal lamina  15  having a circular cylindrical part  15 ′ and an inwardly pointing planar part  15 ″ as well as a gas bag holder ring  16  with a circular cylindrical part  16 ′ and an inwardly pointing planar part  16 ″. The two planar parts  15 ″ and  16 ″ are axially tensioned with one another through rivet connections  30  which are distributed over the periphery, with the edge  18  of the gas bag  13  being included between them. 
     The outer holder sheet metal lamina  15  is secured via securing elements  28  which are only schematically illustrated in FIG. 1 at a suitable part of the likewise only schematically indicated steering wheel  11  of the vehicle. The securing elements  28  are preferably axially resiliently movable so that through an axial pressing onto the non-illustrated cover of the gas bag  13 , for example the horn of the vehicle can be actuated via a suitably arranged switch. 
     At the periphery of the outer holder sheet metal lamina  15  at least three downwardly protruding holder bows  33  are secured with a uniform distribution over the periphery, and indeed in such a manner that a radial bow opening  41  is available below the cylindrical part  15 ′ of the holder sheet metal lamina  15  for holding purposes which are described further below. 
     As can be seen in FIG. 3, a gas bag holder basket  29  on which the folded together gas bag  13  lies extends upwardly from the radially inner edge of the planar part  16 ″ of the gas bag holder ring  16 . The numerous apertures in the gas bag holder basket  29  are primarily for the purpose of a weight saving. In addition the gas required for the inflation of the gas bag  13  should flow in largely without hindrance through the apertures. 
     At the top the module consisting of the gas bag  13  as well as the holder sheet metal lamina  15  and the gas bag holder ring  16  is closed by a cover  40  which is only indicated in broken lines in FIG.  1  and which can break open or fold open during the inflation of the gas bag  13  for the release of the gas bag  13 . The cover  40  is secured in any case at the steering wheel  11  and does not participate in the oscillations of any oscillation absorber masses even when the holder sheet metal lamina  15  and the gas bag holder ring  16  are intended to belong to it. 
     Beneath the gas bag holder basket  29  and radially inside the ring-shaped holder sheet metal lamina  15  or the gas bag holder ring  16  respectively there is located a gas generator  12  which—as can also be seen from FIG.  2 —has a substantially circular cylindrical form with a central axis  19  and is provided at its periphery with a row of gas outlet openings  20  which are distributed as uniformly as possible over the periphery. The central axis  19  of the gas generator  12  should coincide with the axis of rotation of the steering wheel  11  or at least be near the latter and parallel to it. 
     Round about the gas generator  12  a plate-shaped generator carrier  14  is secured to the latter which in accordance with FIG. 2 is designed in the shape of a rectangle and has bores  35  at its corners. Beneath the generator carrier  14  is located an adapter ring  24  which is concentric with the central axis  19  and which preferably consists of sheet metal and has securing holes  36  which align with the bores  35  of the generator carrier  14 . Bolts  26  are pushed through the bores  35  and the securing holes  36  onto which nuts  27  are screwed which serve for the securing of the generator carrier  14  at the adapter ring  24 . 
     The adapter ring  24  is used in order to be able to connect standard gas generators to special steering wheels of a motor vehicle. Accordingly, the outer dimensions of the adapter ring  24  are matched to the vehicle in which the airbag arrangement is to be installed, the inner dimensions to the generator carrier  14 . 
     In accordance with FIGS. 1 and 2 the adapter ring  24  has radially outwardly an upwardly pointing edge which corresponds to a plate edge and which in the assembled state in accordance with FIG. 1 lies axially at a slight distance opposite to the lower radially outward region of the planar part  15 ″ of the outer holder sheet metal lamina  15 . Through this a free lateral oscillation of the gas generator  12  is ensured. A bulge-like ring seal  32  is provided radially inwardly from the edge  31  at the adapter ring  24  which is axially braced in the assembled state both at the adapter ring  24  and at the planar part  15 ″ of the holder sheet metal lamina  15  so that an elastic distance holder is present between the relevant components here which however permits a relative movement of the two components perpendicular to the central axis  19  without further ado. 
     Furthermore, the ring seal  32  is designed in such a manner that it can pivot in the presence of pressure stressing radially from inside about a ring line  37  which is indicated in FIG. 2 radially outwardly into the gap between the edge  31  and the planar part  15 ″ of the holder sheet metal lamina  15  in order to seal off the gap between these two constructional elements. 
     Since in a pressure stressing by the gas generator  12  the adapter ring  24  and the gas bag holder means  15 ,  16  are pressed apart axially, radial holder projections  34  which are visible in FIGS. 1 and 2 reach into the radial openings  41  of the bow  33  in such a manner that the axial moving apart of the gas generator  12  and the holder means  15 ,  16  is limited to a value such that in particular in the region of the radially outwardly pressed ring seal  32  an unobjectionable tightness is still maintained. 
     In order to be able to exploit the mass of the gas generator  12  and the components  14 ,  24  attached to it for the oscillation absorption in accordance with the invention, bores  23  which are distributed over the periphery of the adapter ring  24  are provided at which in each case an elastic sleeve  21  which extends in the direction towards the steering wheel  11  is secured. The elastic sleeve  21  is provided below with a contraction  21 ′ and a radially inwardly pointing ring bulge  21 ″ which engages into a ring groove  22 ″ which is provided at a catcher prong  22 . At the ring groove  22 ″ there adjoins upwardly a contracting conical region  22 ′″ which merges upwardly into a cylindrical upper end region  22 ′. The diameter of the upper end region  22 ′ and of the conical region  22 ′″ is chosen in such a manner that in this region the catcher prong  22  has a significant distance on all sides from the elastic sleeve  21 . A ring pocket  25  which ensures an oscillation clearance is thus present between the catcher prong  22  and the elastic sleeve  21 . 
     Beneath the ring groove  22 ″ is located a hexagon  22 ″″ which is intended for the application of a tool and from which e.g. a securing pin  22 ″″′ which is provided with a thread and which is secured at a suitable location in the steering wheel  11  extends downwardly. 
     In the sense of a kinematic reversal the catcher prongs  22  can also be attached firmly to the adapter ring  24 , and the elastic sleeves  21  which extend downwardly from the catcher prongs  22  can engage into corresponding bores of the steering wheel  11 . 
     The mounting and the functioning of the described airbag arrangement are as follows: 
     The airbag module with a loosely hung in absorber module (gas generator  12  with generator carrier  14  and adapter ring  24 ) is introduced into the steering wheel  11  in the direction of the steering wheel axis, and indeed in such a manner that the bores  23  are oriented with the catcher prongs  22 . In this the ring bulges  21 ″ of the elastic sleeves  21  slide on the conical region  22 ′″ of the catcher prongs  22  while downwardly widening elastically until they finally snap in radially into the ring grooves  22 ″ of the catcher prongs  22 . Then the non-oscillating part of the airbag module, consisting of the gas bag securing means  15 ,  16  and the parts attached thereto are secured separately to the steering wheel via the schematically indicated securing elements  28 . 
     A removal of the airbag module is also possible without further ado, with the fastening of the gas bag securing means  15  to the steering wheel  11  first being eliminated and then the module being axially drawn off without damage from the catcher prongs  22 . 
     After the mounting the gas generator  12  with the generator carrier  14  and the adapter ring  24  can oscillate freely in the direction perpendicular to the steering wheel axis  19  to an extent which is limited by the dimensions of the ring pockets  25 . Since the gas bag  13  lies in contact on the upper side of the holder basket  29 , which represents a constituent of the non-oscillating part of the airbag module, the free oscillation of the gas generator  12  is not hindered by the gas bag  13  lying on it. The preferred oscillatory directions in the x, y plane are shown in FIG.  2 . In the z direction, on the other hand, no noticeable oscillation takes place. 
     In the event of an accident, gas flows out of the gas outlet openings  20  of the gas generator  12  into the opening  17  of the gas bag  13  and inflates the latter after a breaking open of the cover  40  (FIG.  1 ). 
     Since however a distance is present between the periphery of the gas generator  12  and the inner edge of the gas bag holder ring  16  which permits the lateral oscillatory movements of the gas generator  12 , the gas can also enter from the gas outlet openings  20  through this ring gap  38  into the space between the adapter ring  24  and the gas bag holder means  15 ,  16 . In this the gas pressure stresses the ring seals  32  which are located between these two parts and presses them radially outwardly into the contracting gap  39  between the adapter ring  24  and the planar part  15 ″ of the outer holder sheet metal lamina  15 . Through this the only non-tightness which is provided as a result of the oscillatory movability of the gas generator  12  is eliminated and it is provided for that the gas from the gas generator  12  is available at least predominantly for the inflation of the gas bag  13 . 
     The ring seal bulge  32  thus wedges itself in the gap  39  through the outflowing gas. Since the gas bag securing means  15 ,  16  and the adapter ring  24  are also pressed apart by the gas pressure it is necessary to limit this movement apart in the axial direction, which takes place through abutment of the radial holder projections  34  of the adapter ring  24  which engages into the radial opening  41  of the bow  33  at the web  33 ′ of the bow  33 . 
     The invention thus exploits the mass of the gas generator  12  and the components  14 ,  24  which are secured to it as an oscillation absorber mass in a steering system, with an unobjectionable as well as a gas-loss-free inflation of the gas bag  13  being ensured in spite of the oscillatory decoupling of the gas generator  12  from the gas bag securing means  15 ,  16 . 
     For the sake of clarity the oscillating parts of the described airbag module are illustrated in FIG.  2  and the non-oscillating parts of the described airbag module are illustrated separately in FIG. 3, with the gas bag  13  and the cover  40  not being indicated, in contrast to FIG.  1 . 
     LIST OF REFERENCE NUMERALS 
       11  steering wheel 
       12  gas generator 
       13  gas bag 
       14  generator carrier 
       15  outer holder sheet metal lamina 
       15 ′ circular cylindrical part of the outer holder sheet metal lamina 
       15 ″ planar part of the outer holder sheet metal lamina 
       16  gas bag holder ring 
       16 ′ circular cylindrical part of the gas bag holder ring 
       16 ″ planar part of the gas bag holder ring 
       17  opening of the gas bag 
       18  edge of the gas bag 
       19  central axis of the gas generator 
       20  gas outlet opening 
       21 ′ elastic bearing (elastic sleeve) 
       22  catcher prong 
       22 ′ upper end 
       22 ″ ring groove 
       22 ″′ conical region 
       22 ″″ hexagon 
       24 ″″′ securing pin 
       23  bore 
       24  adapter ring 
       25  ring pocket 
       26  bolt 
       27  nut 
       28  securing element 
       29  gas bag holder basket 
       30  rivet connection 
       31  edge 
       32  movable ring seal 
       33  holder bow 
       33 ′ web 
       34  holder projections 
       35  bore 
       36  securing holes 
       37  ring line 
       38  ring gap 
       39  gap 
       40  cover 
       41  bow opening