Abstract:
The present invention includes an airbag arrangement which includes an airbag, a gas tube connected to the airbag, a gas generator having at least one gas outlet, and a jointed connection designed as a ball and socket joint for connecting the gas outlet with the gas tube.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a gas generator comprising at least one gas outlet to which a gas tube is connected. 
     Gas generators of this kind are for example used in motor vehicles and serve to inflate the airbag in the event of an accident via the gas tube which is plugged into the interior of a folded airbag and which can be provided with a plurality of gas outlet openings. The positions at which the gas generator and the airbag are arranged in the vehicle are predetermined so that the gas generator and the gas tube are to be mounted at a relative orientation which is matched to the respective vehicle. In this it must also be taken into account that relative movements between the gas tube and the gas generator can be produced through vehicle body movements which arise during the operation of the vehicle. 
     The problem (object) on which the invention is based is to provide a gas generator of the initially named kind which is as simple to mount as possible and the capability of functioning of which in the mounted state is lastingly ensured. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention a jointedly connected component consisting of a gas generator and a gas tube is created which can be adapted in a simple manner to the circumstances of the respective vehicle. The invention is advantageous in particular for applications in which long gas tubes are used to inflate side airbags which expand downwardly starting from the vehicle roof in the manner of a curtain in the event of an accident. In particular in gas tubes with a great length, which e.g. can amount to more than 1 m, the invention prevents small angular movements during the mounting of the gas generator from resulting in large deviations in the desired position of the gas tube in the vehicle, since the angular position of the gas tube can be matched exactly to the circumstances of the respective vehicle. Low and in principal acceptable installation tolerances in the region of the gas generator can thus not lead to unacceptable deviations from the predetermined installation position of the gas tube and of the airbag. 
     The jointed connection which is provided in accordance with the invention between the gas outlet of the gas generator and the gas tube thus enables installation tolerances in the region of the gas generator to be compensated already at the gas generator through a corresponding displacement of the gas tube, and thus a correct position of the gas tube and the airbag in the vehicle always to be ensured. In this way the mounting of airbag modules is considerably simplified through the invention. 
     A further advantage of the jointed connection in accordance with the invention consists in that movements of the vehicle body, which arise during the operation of the vehicle and which lead to a relative movement between the gas generator and the gas tube, are compensated, whereby the occurrence of damages and leaks in the region of the connection between the gas tube and the gas generator is avoided. 
     In accordance with a preferred embodiment of the invention the jointed connection is designed as a ball and socket joint. 
     Through this the gas tube can be adjusted continuously in any desired direction. 
     In accordance with a further preferred exemplary embodiment of the invention the gas tube is secured with a clamping ring to the gas outlet, with a run-up inclination being provided at the gas outlet and/or at the clamping ring. 
     Through this a relative movement between the clamping ring and the gas outlet in a direction which is predetermined by the run-up inclination can be produced during the clamping of the clamping ring in order to draw the gas tube towards the gas outlet and to fix it between the clamping ring and the gas outlet by means of the clamping ring. 
     If in accordance with a further preferred embodiment of the invention the clamping ring is held by a clamp and an airbag is clamped between the clamping ring and the clamp, the gas tube can be held at the gas outlet and the airbag at the clamping ring at the same time by a tightening of the clamp. In this way the pre-mounting of the component comprising a gas generator, the gas tube, the airbag and the clamping ring can be considerably simplified. 
     In accordance with a further preferred exemplary embodiment of the invention a line contact is provided between a clamping ring and the gas tube. 
     In this way, the friction between the clamping ring and the gas tube is minimized so that the gas tube can be easily adjusted and nevertheless be held securely at the gas outlet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in the following in an exemplary manner with reference to the drawings. Shown are: 
     FIG. 1 a  a side view of an arrangement consisting of a gas tube, a clamping ring and a gas outlet of a partly illustrated gas generator in accordance with an embodiment of the invention, 
     FIG. 1 b  a sectioned view in accordance with line B/B of FIG. 1 a,    
     FIG. 1 c  a view corresponding to FIG. 1 b  with a gas tube at an inclination with respect to the gas outlet, and 
     FIGS. 2-4 various possibilities in accordance with the invention of the attachment of a gas outlet to a partly illustrated gas generator. 
    
    
     FIGS. 1 a ,  1   b  and  1   c  each show a pre-mounting state in which a gas tube  14  is fixed by means of a cylindrical clamping ring  16  to a gas generator in accordance with the invention, of which in each case only a gas outlet  12  is illustrated which is formed as a separate component. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 a  only a part of the gas outlet  12  of the gas generator can be seen. As the sectional view of FIG. 1 b  shows, the gas outlet  12  is surrounded by the clamping ring  16 , which can be contracted by means of the clamp  18  and which serves to fix the gas tube  14 , which is jointedly connected to the gas outlet  12 , to the gas outlet  12 . The clamp  18  is a flat metal strip and is arranged in a correspondingly designed peripheral cut-out on the outer side of the clamping ring  16 . 
     The gas outlet  12  can be attached via a coupling section  52  to the gas generator. The end of the gas outlet  12  which cooperates with the gas tube  14  is designed as a spherical region and comprises at its outer side a convexly curved support surface  20  which merges into a ring shoulder  22 . The transition region between the support surface  20  and the ring shoulder  22  is cut free or, respectively, provided with an undercut  24 . 
     At its side facing away from the convex support surface  20 , the ring shoulder  22  has a run-up inclination  28  which extends at an inclination with respect to a middle axis  26  of the gas outlet  12 . 
     The clamping ring  16  comprises a ring-shaped section  30 , from which legs  32  project which are uniformly distributedly arranged in the peripheral direction. In FIG. 1 a  only end regions of the legs  32  can be seen which in each case are provided with a radially inwardly projecting holder section  34 . The clamping ring  16  is designed in a single piece and consists of a plastic material of high strength so that a comparatively large force is required for pressing the legs  32  together or apart, respectively. 
     The holder sections  34  of the legs  32  are in each case provided with a run-up inclination  36  which cooperates with the run-up inclination  28  of the ring shoulder  22 . The clamping ring  16  is latched to the gas outlet  12  in such a manner that the legs  32  engage with their holder sections  34  behind the ring shoulder  22  in a locking manner. 
     The inner side of the clamping ring  16  has a support surface  38  comprising a planar region  40  which extends at an inclination with respect to the middle axis  26  of the gas outlet  12  and a spherical, concavely curved region  42 , with the concave region  42  being less strongly curved than the convex support surface  20  of the gas outlet  12 . The support surface  38  is formed by the inner side of the ring section  30  as well as by the inner sides of the legs  32 , with it being possible for the ratio of the respective contributions to vary in dependence on the length of the legs  32 . The legs  32  preferably form the planar region  40 , and the ring section  30  preferably forms the concave region  42  of the support surface  38 . 
     In the pre-mounting state in accordance with FIGS. 1 a ,  1   b  and  1   c , the ring section  30  of the clamping ring  16  extends beyond the free end of the gas outlet  12  and has a flange  50 . In the region of the flange  50 , the gas outlet  12  is designed conically with an inner wall extending towards the coupling section  52  at an inclination with respect to the middle axis  26 . 
     At its end cooperating with the gas outlet  12 , the gas tube  14 , which is manufactured from aluminum, has a spherical region  44  which forms a transition region between a tube section  46  of smaller diameter and a circular cylindrical end section  48  of larger diameter. The length of the tube section  46  varies in dependence on the circumstances in the respective vehicle and can for example amount to more than 1 m. Furthermore, the tube section  46  can be provided with gas outlet holes via which gas, which is pressed into the gas tube  14  by means of the gas generator, can flow into a non-illustrated airbag. 
     The curvature of the spherical region  44  of the gas tube  14  corresponds to the curvature of the concave support surface  20 . As a result the gas tube  14  is more strongly curved in the spherical region  44  than the concave region  42  of the clamping ring  16  so that a line contact is present between the clamping ring  16  and the gas tube  14 . 
     The inner diameter of the gas tube  14  in the region of its circular cylindrical end section  48  is slightly smaller than the maximum diameter of the gas outlet  12  in the region provided with the spherical support surface  20 . As a result, a resistance is to be overcome in plugging the gas tube  14  onto the gas outlet  12 , with the gas outlet  12  being non-losably held at the gas outlet  12  and thus at the gas generator in the state of being plugged on and not yet secured by the clamping ring  16 . 
     Between the gas tube  14  and the gas outlet  12  there is a jointed connection when plugged together, with the spherical region  44  of the gas tube  14  and the spherical support surface  20  of the gas outlet  12  cooperating in the manner of a ball and socket joint. The gas tube  14  can therefore be tilted in any desired direction with respect to the gas generator. The maximum adjustment angle, that is, the maximum angle between the middle axis  26  of the gas outlet  12  and the middle axis of the gas tube  14 , is determined by the flange  50  of the clamping ring  16 . 
     In FIG. 1 c , the gas tube  14  is illustrated at an inclination with respect to the middle axis  26  of the gas outlet  12 , with the maximum adjustment angle not yet being achieved. From FIG. 1 c  it can be seen that the undercut  24  of the gas outlet  12  serves to enable a movement of the front-end tube end along the spherical support surface  20  towards the middle axis  26  of the gas outlet  12  during angular adjustment of the gas tube  14 . 
     For the manufacture of the jointed connection, the gas tube  14  is first plugged onto the gas outlet  12  so that the inner side of the spherical region  44  of the gas tube  14  lies in contact at the spherical support surface  20  of the gas outlet  12 . 
     Then, the clamping ring  16  is pushed over the gas tube  14  and pressed onto the gas outlet  12 , with the legs  32  being pressed out vardly due the ring shoulder  22  and finally snapping with their holder sections  34  behind the ring shoulder  22 , so that the run-up inclinations  28 ,  36  make contact with one another and the clamping ring  16  is latched to the gas outlet  12 . 
     The clamping ring  16  can already be pushed over the gas tube  14  prior to plugging the gas tube  14  onto the gas outlet  12 , with the clamping ring  16  lying loosely in contact with its legs  32  on the spherical region  44  and with it not being possible for the clamping ring  16  to get lost. 
     Airbag  60  can be secured to the clamping ring  16  for example by being drawn over the gas tube  14  and being arranged with its mouthpiece between the clamping ring  16  and the clamp  18  prior to tightening the clamp  28 . 
     By tightening of the clamp  18 , the free end regions of the legs  32  which are provided with the holder sections  34 , are pressed radially inwardly so that the holder sections  34  slide with their run-up inclinations  36  along the run-up inclination  28  of the ring shoulder  22  and in this provide for a movement of the clamping ring  16  parallel to the middle axis  26  towards the coupling section  52  of the gas outlet  12 . 
     As a result, the gas tube  14  is clamped with its spherical region  44  between the support surface  20  of the gas outlet  12  and the support surface  38  of the clamping ring  16  through tightening of the clamp  18 . 
     In this the clamp  18  can first be tightened only slightly in order to exert a comparatively low clamping force on the gas tube  14 , which certainly permits the setting of the desired angular position, but prevents the gas tube  14  from subsequently changing the adjusted position by itself. As a result of the line contact between the clamping ring  16  and the gas tube  14 , the frictional forces which are to be overcome for moving the gas tube  14 , are relatively low. By tightening the clamp  18 , the gas tube  14  can then be fixed in its final position. 
     Through the mutually matched shapes of the spherical support surface  20  of the gas outlet  12  and the spherical region  44  of the gas tube  14 , the gas imperviousness in the region of the transition between the gas outlet  12  and the gas tube  14  is ensured even when a change of angular position takes place between the gas tube  14  and the gas outlet  12  while the clamping ring  16  is tightened. 
     It can be seen in particular in FIG. 1 c  that only at maximum inclination of the gas tube  14 —which has not yet been reached in FIG. 1 c —, when the gas tube  14  lies in contact with its tube section  46  at the flange  50  of the gas outlet  12 , does the circular cylindrical end section  48  of the gas tube  14  extend approximately parallel to the planar region  40  of the support surface  38  of the clamping ring  16 . 
     The maximum clamping force which can be exerted on the gas tube  14  by means of the clamping ring  16 , is determined by the maximum diameter of the ring shoulder  22 , which in the pre-mounting state in accordance with FIGS. 1 a ,  1   b  and  1   c  lies in contact at the inner wall of the clamping ring  16  in the region of the transition between the planar region  40  and the holder sections  34  of the legs  32 . Thus, the legs  32  cannot be pressed together any further, so that the clamping ring  16  can not be moved any further towards the coupling section  52  through further tightening of the clamp  18 , and the clamping force which is exerted on the gas tube  14  can not be increased any further. 
     Following the mounting of the gas generator in the vehicle, first the desired angular position of the gas tube  14  is set. The gas tube  14  may previously be subjected to a comparatively low clamping force through tightening of the clamp  18 , in order that the gas tube  14  remains in the respective set position and does not change the adjusted position by itself, in particular due to its own weight. Once the gas tube  14  has been brought into the predetermined position, it is fixed by tightening the clamp  18 . The maximum force which can be achieved can be dimensioned in such a manner that a relative movement between the gas tube  14  and the gas generator is still possible in order to be able to compensate movements of the vehicle body. 
     In accordance with FIG. 2, the gas outlet  12  is designed as a separate component and is welded via a welding seam  54  with its coupling section  52  to the merely partly illustrated gas generator  10 . In FIG. 2 a sieve unit  56  can also be seen which prevents the intrusion of particles into the gas tube  14  which could lead to damage to the non-illustrated airbag. 
     In the embodiment in accordance with FIG. 3, the gas outlet  12 , which is again designed as a separate component, is screwed to the gas generator  10 . The gas generator  10  is provided with a threaded extension  58  of reduced diameter which has an outer thread and onto which the gas outlet  12  is screwed with its coupling section  52 . The threaded extension  58  is welded to the gas generator  10  via a welding seam  54 . In the embodiment in accordance with FIG. 3, the gas generator  10  is provided with a sieve unit  56 , too. 
     In the embodiment of FIG. 4, the coupling section  52  of the gas outlet  12  is provided with a thread on its outer side and is screwed into the threaded extension  58  of the gas generator  10 . The gas generator  10  is welded to the threaded extension  58  via a welding seam  54  and is provided with a sieve unit  56 . 
     In principle the threaded extension  58  may also be designed in each case in a single piece with the gas generator  10 . 
     In deviation from the embodiments described above, the gas outlet  12  may also be designed as an integral constituent of the gas generator  10 . 
     List of Reference Symbols 
       10  gas generator 
       12  gas outlet 
       14  gas tube 
       16  clamping ring 
       18  clamp 
       20  support surface 
       22  ring shoulder 
       24  undercut 
       26  middle axis 
       28  run-up inclination 
       30  ring section 
       32  legs 
       34  holder sections 
       36  run-up inclinations 
       38  support surface 
       40  planar region 
       42  concave region 
       44  spherical region 
       46  tube section 
       48  end section 
       50  flange 
       52  coupling section 
       54  welding seam 
       56  sieve unit 
       58  threaded extension