Patent Publication Number: US-2004041372-A1

Title: Gas bag module

Description:
TECHNICAL FIELD  
       [0001] The invention relates to a gas bag module for a vehicle occupant restraint system.  
       BACKGROUND OF THE INVENTION  
       [0002] A typical gas bag module comprises a housing, a gas bag held in the housing, a gas generator and a holding ring.  
       [0003] To fasten a gas bag and/or a gas generator to the module housing, a so-called holding ring or retainer ring is used as standard practice, which is placed into the inflation opening of the gas generator and which is provided for example with threaded pins which project through into openings provided on the gas bag and on the housing, so that by means of a screw coupling the gas bag can be securely connected with the housing. In so doing, the holding ring secures the fabric all around the inflation opening of the gas bag on the housing. The holding ring can additionally grasp a flange of the gas generator, so that the latter can also be secured on the housing by means of the holding ring.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004] It is an object of the invention to provide a secure fastening of the gas bag on the housing, which, at the same time, can be carried out quickly.  
       [0005] This is successfully achieved by a gas bag module comprising a housing, a gas bag held in the housing, a gas generator and a holding ring, by means of which at least one of the gas bag and the gas generator is fastened to the housing. At least one separate fastener (i.e. the fastener defines a separate part) is provided, which has at least one wedge-shaped section. The holding ring has push-in sections for inserting the fastener. The wedge-shaped section of the fastener is pushed into the push-in section to be wedged therein.  
       [0006] The fixing of the holding ring on the housing takes place by means of the pushed-in fastener, so that a saving of time can be achieved compared with a conventional screw connection.  
       [0007] The “wedge-shaped” section is to be understood as a section of the fastener with a wedge-shaped, trapezoidal or tapered cross-section viewed in longitudinal direction of the fastener.  
       [0008] The push-in direction of the fastener can lie substantially perpendicular or substantially parallel to an axial direction of the gas bag module.  
       [0009] According to a first preferred embodiment of the invention, the push-in section is formed by a curved tongue. This tongue can be produced for example by two preferably parallel slits being introduced into the holding ring and the material situated between the slits being bent out perpendicularly from the ring plane.  
       [0010] The fastening of the holding ring on the housing takes place in this embodiment in that the tongue projects through an opening formed in the housing and the fastener, pushed through the tongue, lies against the holding ring and against the housing, the fastener being wedged between the inner side of the tongue and the housing base.  
       [0011] According to a second preferred embodiment, the push-in section is formed in at least one detent pin arranged on the holding ring. The detent pin can be constructed in one piece with the holding ring. Here, the detent pin is spread open through the fastener, which fixes the holding ring on the housing and prevents an unintentional loosening of the detent connection.  
       [0012] The fastener is preferably a pin-shaped component which is separate from the holding ring and the housing.  
       [0013] It is conceivable to arrange several fasteners on one component.  
       [0014] The push-in section has preferably at least partially a trapezoidal, tapered or wedge-shaped cross-section, which is advantageously adapted to the cross-section of the fastener, in order to increase the wedging effect. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIG. 1 shows a diagrammatic semilateral section of a gas bag module according to the invention in accordance with a first embodiment;  
     [0016]FIG. 2 shows the cutout designated by X of FIG. 1 in an enlarged illustration;  
     [0017]FIG. 3 shows a section along the line III-III of FIG. 2;  
     [0018]FIG. 4 shows a diagrammatic semilateral section of a gas bag module according to the invention in accordance with a second embodiment;  
     [0019]FIG. 5 shows the cutout designated by X of FIG. 4 in an enlarged illustration;  
     [0020]FIG. 6 shows a diagrammatic semilateral section of a gas bag module;  
     [0021]FIG. 7 shows a cutout of the assembly of gas bag holding ring and module housing of FIG. 6 in a top view;  
     [0022]FIG. 8 shows a section along the line VIII-VIII of FIG. 7;  
     [0023]FIG. 9 shows a diagrammatic semilateral section of a further gas bag module; and  
     [0024]FIG. 10 shows the cutout designated by X of FIG. 9 in an enlarged illustration. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0025] The gas bag module  10  shown in FIG. 1 according to a first embodiment of the invention, which is provided for installation in a steering wheel  12 , has a module housing  14  with a covering cap  16  arranged thereon, a folded gas bag  18  arranged in the module housing  14 , a gas generator  20  likewise arranged in the module housing, and a holding ring  22  fastening the gas bag  18  and the gas generator  20  on the module housing  14 .  
     [0026] The gas bag module  10  is connected with the steering wheel  12  in a known manner, e.g. by means of a detent connection  24 .  
     [0027] The direction A shown in the Figures corresponds to an axial direction of the gas bag module  10  and is usually conform to a direction in which the gas bag exits the module on inflation. In a steering wheel gas bag module, the direction A coincides with the axis of the steering wheel.  
     [0028] The holding ring  22  is placed into the gas bag, so that the gas bag  18  is clamped around the inflation opening between the holding ring  22  and the module housing  14 .  
     [0029] The holding ring  22  has several, e.g. four, curved tongues  26  at intervals along its periphery, which are formed here by parallel notches in the holding ring  22 , the ring section lying between the notches being bent outwards from the ring plane. The tongues  26  form push-in sections  28  for wedge-shaped sections of fasteners  30 , the fasteners  30  forming separate parts.  
     [0030] The holding ring  22  is arranged so that the tongues  26  project through openings  32 , provided in the module housing  14 , to the exterior of the gas bag module. The wedge-shaped sections of the fasteners  30  are pushed into the push-in sections  28  so that they lie both against the inner sides of the tongues  26  and also on the base of the module housing  14 .  
     [0031] The fasteners  30  are pushed so far into the push-in sections  28  that they are securely wedged therein. By means of this wedging effect, the holding ring  22  is fixed to the module housing  14 .  
     [0032] In this embodiment, the push-in direction E of the fasteners  30  is perpendicular to the axial direction A of the gas bag module.  
     [0033] Viewed in axial direction of the fasteners  30 , i.e. in the Figures in a section along the direction of arrow E, the latter have a wedge-shaped, tapered or trapezoidal cross-section. The cross-section of the tongues  26  is adapted in longitudinal direction to the cross-section of the fasteners  30 , the cross-section of the tongues being also wedge-shaped, tapered or trapezoidal (see FIG. 3).  
     [0034] In FIGS. 4 and 5, a second embodiment is shown of a gas bag module  10  according to the invention. Here, the principle of fastening the holding ring  222  on the housing  14  is realized by the wedging of a wedge-shaped fasteners  230  in a different manner.  
     [0035] As can be seen in FIG. 5, several detent pins  250  are formed on the holding ring  222  in one piece therewith, e.g. four of them, which respectively have a push-in section  228  in longitudinal direction. The longitudinal direction of the detent pins  250  coincides with the axial direction A of the gas bag module, when the holding ring is inserted into the gas bag module. The detent pins  250  are provided with contact surfaces  252  which lie against the underside of the module housing  14 . The fasteners  230  are pushed in after the detent pins  250  have been inserted through the openings  32  provided for this in the gas bag  18  and in the module housing  14 . By the pushing in of the wedge-shaped fasteners  230  from the underside of the module, the walls of the push-in sections  228  and hence of the detent pins  250  are pressed apart and thus the detent pins  250  are secured in the openings  32  of the module housing  14  against traction in axial direction A.  
     [0036] In this embodiment, the push-in direction E of the fasteners is parallel to the axial direction A of the gas bag module.  
     [0037] A further gas bag module is shown in FIGS.  4  to  7 .  
     [0038] In this gas bag module, the connection between the holding ring  322  and the housing  314  is formed by an interweaving of tongues  330  arranged on the holding ring  322  and cross-pieces  340  constructed on the housing  314 .  
     [0039] As can be seen in FIG. 7, two oppositely directed tongues  330  are formed in the holding ring  322  by the formation of an S-shaped slit  342 . In the module housing  314 , at the same site two cross-pieces  340 , running perpendicularly to the tongues  330 , are constructed, likewise by the provision of slits in the module housing  314 .  
     [0040] Several such slit/tongue pairs  330 ,  340 , e.g. four of them, are distributed along the periphery of the ring  322 .  
     [0041] The tongues  330  engage through openings in the gas bag  18  and are interwoven with the cross-pieces  340 .  
     [0042] A different geometry of tongues and cross-pieces is of course also conceivable, just as it is possible to construct the tongues, in reverse, on the housing, and the cross-pieces on the holding ring.  
     [0043] The advantage in such a connection lies inter alia in the small space requirement in axial direction A and also in that no additional components are required.  
     [0044] In FIGS. 9 and 10, a different type of fastening of a holding ring  422  on a module housing  414  is shown.  
     [0045] On the holding ring  422 , several bent detent arms  430  are constructed distributed along the periphery, the extent of which in radial direction is greater than the extent of the openings  32  of the module housing  414 .  
     [0046] The detent arms  430  have such a high elasticity that they are able to slide in one direction through the openings  32  under elastic deformation. After sliding through, detent surfaces  432  arrive in abutment against the base of the housing  414  and thus prevent a return movement of the detent arms  430 . Hereby, the holding ring  422  is fixed to the module housing  414 . Also in this case, the detent arms  430  extend through openings in the gas bag  18  and thus fix the gas bag  18 .  
     [0047] The described connections can of course also be used for fastening a gas bag and/or a gas generator on a gas generator carrier.