Gas bag module for a vehicle occupant restraint system

Abstract

Gasbag module with an assembly (20), in particular for a vehicle occupant restraint system, comprising a gas generator (16) with a fastening flange (32) and a generator bearing part (18) for elastically mounting the gas generator (16), and with a generator carrier (12), wherein the generator bearing part (18) has a holding part (24) made of a metal sheet and at least one fastening foot (26) made of an elastic material attached to the holding part (24) for connection to the generator support (12), wherein the holding part (24) and the fastening flange (32) are fastened to one another by plastic deformation of at least one of the two parts, and wherein a plurality of fastening feet (26) are provided which fasten the gas generator (16) to the generator support (12), characterized in that that the fastening feet (26) each have a mounting tongue (38) before being mounted on the generator support (12), which forms the free end of the associated fastening foot (26).

Description

The invention relates to an airbag module for a vehicle occupant restraint system, comprising an assembly of a gas generator with a fastening flange and a generator bearing part for the elastic mounting of the gas generator, having the features in the preamble of claims 1 and 2.A gas bag module of the generic type is already known from DE 10 2007 054 056 A1, in which the gas generator is fastened to a body part via a plurality of support arms, wherein the support arms are formed from an elastomer body.DE 101 31 830 A1 discloses a fastening of a pot gas generator to a frustoconical elastomer spring which surrounds the gas generator in an annular manner.In the case of airbag modules arranged in the steering wheel, vehicle movements which cause oscillations of the steering wheel can lead to undesired effects. This applies all the more if a so-called floating horn module is used, in which the entire airbag module including the relatively heavy gas generator is movably fastened for actuating the horn. There are solutions in which the mass of the gas generator is decoupled from the rest of the airbag module via an interposed elastic element. Such decoupling is complicated, in particular because the space in the steering wheel is very limited. There is therefore a need for a simple, inexpensive and space-saving decoupling of the oscillations of the gas generator.This object is achieved according to the invention by an airbag module having the features of claims 1 and 2.The invention allows a widely used, conventional type of gas generator to be used, so that the gas generator does not have to be tuned specifically to the generator bearing part, as is often the case with conventional bearings for vibration decoupling. Instead, according to the invention, the holding part is preferably plastically deformed in order to permanently fasten the generator bearing part to the flange of the gas generator. Alternatively, the fastening flange can also be formed, or both components can be completely or partially formed. The fastening of the gas generator to the generator carrier and also the decoupling of the gas generator from the elastic material. These prevent a direct transmission of vibrations from the generator support to the gas generator.Optionally, the gas generator can also act as a vibration damper.The holding part is preferably of annular design, so that it can surround the fastening flange.The holding part can be locked on the fastening flange, for example, by crimping, stamping or flanging, wherein both the holding part and the fastening flange can be deformed. Of course, however, any other suitable method of plastic forming can also be used.In order to achieve a stable fastening in a simple manner, the holding part is preferably fastened circumferentially on the gas generator. However, it is also possible to provide a fastening only in sections.According to a preferred embodiment of the invention, the generator bearing part comprises at least one abutment lip made of the elastic material, which extends substantially in an axial direction of the assembly. The stop lip comes into contact with the generator carrier during a vertical movement, i.e. during a movement in the axial direction, and limits the movement path of the gas generator in this direction. Advantageously, in a normal state of the assembly, when it is installed in an airbag module, there is a distance between the stop lip and the generator carrier.In order to ensure a reliable and simple limitation of even vigorous movements of the gas generator, an extension of the holding part protruding in the axial direction can be provided in the region of the stop lip, so that the stability of the stop lip is increased by the metal sheet of the holding part.Preferably, the extension is embedded in the stop lip, wherein advantageously the axially free end of the stop lip is formed only from the elastic material.The extension can be realized, for example, by at least one tongue protruding from the holding part. In this way, simple production of the holding part, for example as a stamped and bent part, is possible.The stop lip is preferably designed to be circumferentially closed at least largely circumferentially, wherein it is advantageously circumferentially closed as far as the geometry of the generator bearing part and of the fastening feet allows.Silicone is preferably used as elastic material, and the fastening foot is preferably injection-molded onto the holding part.The stop lip is also preferably injection-molded onto the holding part. In this way, a stable connection of the parts made of the elastic material to the metal sheet of the holding part is possible with a very flexible geometry in simple production.According to the invention, a plurality of fastening feet are provided which fasten the gas generator to the generator carrier. The fastening feet serve as the only fastening between the assembly and the generator carrier.Each mounting foot has a mounting tongue before being mounted on the generator support, which tongue forms the free end of the mounting foot. The fastening foot can be pulled on this fastening tongue, for example, through an opening in the generator carrier, at which it latches. The mounting tongue is removed after the assembly has been mounted, but it can also remain on the fastening foot.Alternatively, each of the fastening feet has a circumferential groove, in which an edge of the opening in the generator carrier engages, so that the fastening foot latches in the opening and is thus securely fastened to the opening.The stop lip preferably lies opposite an axial and / or a radial stop on the generator carrier, which limit a movement of the gas generator in the axial direction and / or radial direction. By forming the stop in the axial and / or radial direction, a range of movement of the gas generator can be individually predefined. The stop in the axial direction can be formed simply by a surface section of the generator carrier.When the gas generator is activated, the stop lip preferably comes into contact with the generator carrier and brings about a seal between the gas generator and the generator carrier. Due to the impulse of the outflowing gas and the internal pressure of the airbag, the gas generator is pressed in the axial direction in the direction of the generator carrier, so that the stop lip comes into contact with the generator carrier. In this way, it is achieved that the inflation gas for a gas bag provided by the gas generator cannot escape through the gap between the gas generator and the generator carrier. In this case, it is advantageous if the stop lip is designed to be as completely circumferentially encircling as possible. However, it has been found that small gaps in the stop lip do not have a negative effect.Further features and advantages of the invention will become apparent from the following description of an exemplary embodiment, with reference to the attached drawings. In these show:FIG. 1 shows a partially cut-away view of an airbag module according to the invention with an assembly according to the invention; andFIG. 2 shows a section of the airbag module in FIG. 1 in a sectional view.FIG. 1 shows an airbag module 10 which is intended for use in a steering wheel of a passenger car. In a module housing consisting of a generator carrier 12 and a covering cap 14, which is only indicated, an airbag 15 is accommodated in a folded manner. The inflation gas for the airbag 15 is supplied by a here pot-shaped gas generator 16.The gas generator 16 is elastically supported on the generator support 12 via a generator bearing part 18 and together with the generator bearing part 18 forms a prefabricated assembly 20. This provides a certain limited range of movement for the gas generator 16 in all spatial directions.The generator bearing part 18 consists of a holding part 24 made of a metal sheet and of a plurality of fastening feet 26 and a stop lip 28 made of an elastic material. Silicone is used as the elastic material in this example. The fastening feet 26 and the stop lip 28 are injection-molded onto the holding part 24.The holding part 24 is designed here in the form of a circumferential ring which has an L-shaped cross section with a raised outer edge 30. In order to fasten the generator bearing part 18 and the gas generator 16 to one another, the gas generator 16 is inserted into the holding part 24 in such a way that a radially protruding fastening flange 32 which is formed integrally with the gas generator 16 and surrounds the latter in the circumferential direction is arranged within the outer edge 30 of the holding part 24 and rests on the holding part 24.The outer edge 30 is then mechanically formed in such a way that a firm connection to the fastening flange 32 takes place. The forming can be effected, for example, by crimping, embossing or flanging, but also by another suitable deformation. Here, it would also be possible to fully or partially deform the fastening flange 32 instead of the holding part 24. As a result of this measure, the generator bearing part 18 is firmly connected to the gas generator 16, so that the assembly 20 can be prefabricated and handled as a separate unit.In this example, four fastening feet 26 extend in the axial direction perpendicular to the plane defined by the holding part 24, which is designated as the Z direction in FIG. 1. Each of the fastening feet 26 is made entirely of the elastic material and has a circumferential groove 34 formed therein. An edge of an opening 36 in the generator support 12 engages in this groove 34, so that each fastening foot, 26 is firmly fastened to the generator support 12.As an assembly aid, each of the fastening feet 26 has an assembly tongue 38 which initially forms the free end of the fastening foot 26. To fasten the assembly 20 to the generator carrier 12, the mounting tongues 38 are inserted through the openings 36 and then moved by traction on the mounting tongues 38 in the axial direction Z in the direction of the generator carrier 12 until the groove 34 of each of the fastening feet 26 engages in the respective edge of the opening 36. Now, the mounting tabs 38 can be removed, if desired. They do not contribute to the further function of the assembly.The stop lip 28 consists of several segments of circle made of silicone arranged along the circumference of the holding part 24. At the four locations at which the fastening feet 26 are injection-molded onto the holding part 24, the stop lip 28 is interrupted for manufacturing reasons, so that small gaps exist between the stop lip 28 and the fastening feet 26. Alternatively, the stop lip 28 could also merge integrally into the respective fastening foot 26 and thus circulate in a circumferentially closed manner integrally.The generator bearing part 18 is designed such that in the normal state, i.e. without a movement of the gas generator 16 and before it is activated, a small distance in the axial direction Z is formed between the end of the stop lip 28 which is lower in the axial direction and a surface of the generator carrier 12. If the gas generator 16 moves in the axial direction Z, then, with a greater amplitude, the stop lip 28 comes into contact with the generator carrier 12, as a result of which the movement of the gas generator 16 is limited. The surface of the generator carrier 12 serves as an axial stop 39 (see FIG. 2 ).In order to ensure sufficient resistance, particularly in the case of severe movements of the gas generator 16, a plurality of axially protruding extensions 40 of the holding part 24 in the form of angled tongues are embedded in the stop lip 28 along the circumference. The extensions 40 end in front of the free axial end of the stop lip 28, so that the elastic material always comes into contact with the generator carrier 12.A limitation of the movement of the gas generator 16 in the radial direction R is ensured by a stop 42 formed on the generator carrier 12 and provided radially inside the stop lip 28. The stop 42 can be a circumferentially encircling ring or else individual projections on the generator carrier 12 distributed over the circumference.The stop 42 extends in the axial direction Z so far in the direction of the gas generator 16 that there is an overlap with the extension 40. In the normal state, the stop lip 28 is spaced apart from both the axial stop 39 and the radial stop 42. In this case, the stop 42 is formed integrally with the generator carrier 12.During normal driving operation, the elastic material of the fastening feet 26 ensures decoupling of the gas generator 16 from the oscillations of the steering wheel into which the airbag module 10 is inserted. The inflator 16 is free to move within the clearance between the stopper lip 28 and the stoppers 39 and 40. A greater movement is prevented by these stops 39, 40.It is possible to tune the frequency of the vibration system comprising the gas generator 16 and the fastening feet 26 in such a way that the mainly occurring interference frequencies are attenuated or completely attenuated. However, this is not necessary; a pure vibration decoupling can also be provided.If the gas generator 16 is activated so that filling gas flows out of the gas bag, the pressure of the gas flowing out and the increasing filling pressure in the gas bag cause the gas generator 16 to move in the direction of the generator carrier 12, wherein the stop lip 28 comes into flat, largely circumferential contact with the generator carrier 12. In this way, a seal is achieved which prevents gas from flowing out of the airbag 15 through the generator carrier 12. The gaps present here for structural reasons in the periphery of the stop lip 28 have proven to be non-disturbing.It would also be conceivable to provide a plurality of separate holding parts which are arranged distributed along the circumference of the gas generator 16 and which each have one or more fastening feet.Instead of silicone, any other suitable elastic material such as rubber or an elastomer can also be used.

Claims

Airbag module with an assembly (20), in particular for a vehicle occupant restraint system, comprising a gas generator (16) with a fastening flange (32) and a generator bearing part (18) for the elastic mounting of the gas generator (16), and with a generator carrier (12), wherein the generator bearing part (18) has a holding part (24) made of a metal sheet and at least one fastening foot (26) made of an elastic material attached to the holding part (24) for connection to the generator carrier (12), wherein the holding part (24) and the fastening flange (32) are fastened to one another by plastic deformation of at least one of the two parts, and wherein a plurality of fastening feet (26) are provided which fasten the gas generator (16) to the generator carrier (12), characterized in that the fastening feet (26) each have a mounting tongue (38) before mounting on the generator carrier (12), which forms the free end of the associated fastening foot (26).Airbag module with an assembly (20), in particular for a vehicle occupant restraint system, comprising a gas generator (16) with a fastening flange (32) and a generator bearing part (18) for the elastic mounting of the gas generator (16), and with a generator carrier (12), wherein the generator bearing part (18) has a holding part (24) made of a metal sheet and at least one fastening foot (26) made of an elastic material attached to the holding part (24) for connection to the generator carrier (12), wherein the holding part (24) and the fastening flange (32) are fastened to one another by plastic deformation of at least one of the two parts, and wherein a plurality of fastening feet (26) are provided which fasten the gas generator (16) to the generator carrier (12), characterized in that each fastening foot (26) has a circumferential groove (34), into which an edge of an opening (36) in the generator carrier (12) engages.The airbag module according to claim 1 or 2, characterized in that the holding part (24) is annular.The airbag module according to any one of the preceding claims, characterized in that the holding part (24) is locked on the fastening flange (32) by crimping, stamping or flanging.The airbag module according to claim 4, characterized in that the holding part (24) is fastened circumferentially on the gas generator (16).The airbag module according to any one of the preceding claims, characterized in that the generator bearing part (18) comprises at least one stop lip (28) made of the elastic material, which extends substantially in an axial direction (Z) of the assembly (20).The airbag module according to claim 6, characterized in that at least one extension (40) of the holding part (24) protruding in the axial direction (Z) is provided in the region of the stop lip (28).The airbag module according to claim 7, characterized in that the extension (40) is embedded in the stop lip (28).The airbag module according to one of claims 7 and 8, characterized in that the extension (40) is formed by at least one tongue protruding from the holding part (24).The airbag module according to any one of claims 6 to 9, characterized in that the stop lip (28) is designed to be at least largely circumferentially closed circumferentially.The airbag module according to any one of claims 6 to 10, characterized in that the stop lip (28) is opposite an axial and / or a radial stop (42) on the generator carrier (12), which limits a movement of the gas generator (16) in the axial direction (Z) and / or radial direction (R).The airbag module according to any one of claims 6 to 11, characterized in that the stop lip (28) comes into contact with the generator carrier (12) upon activation of the gas generator (16) and brings about a seal between the gas generator (16) and the generator carrier (12).The airbag module according to any one of the preceding claims, characterized in that the elastic material is silicone and the fastening foot (26) is preferably injection-molded onto the holding part (24).

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