Airbag module having an elastically mounted gas generator

An airbag module having an elastically mounted gas generator. An easily fittable, elastic mounting is provided for mounting the the gas generator in such a manner that it can be used irrespective of the shape of the diffuser or of another housing surrounding the gas generator. The gas generator is mounted by means of an elastic subassembly, which has retaining element running obliquely upward, i.e., obliquely in the direction of the covering, and retaining element running obliquely downward, i.e., obliquely in the direction opposed to the aforementioned direction. The two retaining elements are fastened to the gas generator or to a section of the airbag module.

BACKGROUND

The invention relates to an airbag module having an elastically mounted gas generator and, in particular, to an airbag module having an elastically mounted gas generator with an airbag and with a covering facing the passenger compartment, in particular for steering wheels.

Airbag modules having elastically mounted gas generators are preferably provided in steering wheels in order to reduce the tendency of the steering wheel to vibrate. The elastic mounting of the gas generator enables vibrations to be decoupled from the steering wheel. Given appropriate dimensioning of the gas generator, the gas generator may also be used as a vibration damper.

European Patent No. EP 1 020 332, hereby incorporated by reference, discloses an airbag module in which elastic bushings are provided in the region of the fastening screws of the gas generator. German Patent No. DE 201 08 594 U1, hereby incorporated by reference, discloses an airbag module in which the gas generator is retained by an elastic element without screwed connections being provided in the region of the element. The elastic element provided in this airbag module is a cross-sectionally closed hollow profile with a circumferential wall. The radial outer side of the wall rests on one side on the gas generator and on the other side on a retaining part on the module.

One way of securing the gas generator is achieved by the gas generator having a retaining flange with a respective elastic element resting on the upper and lower sides thereof, and by the elastic elements being pressed against each other by retaining parts.

Another way of securing the gas generator is by the gas generator having a retaining flange and an elastic element extending from the upper side of the flange and along the circumferential edge as far as the lower side of the flange, and by the elastic element being pressed against the upper and lower sides of the flange by retaining parts.

A disadvantage of this known airbag module is that a step-shaped diffuser must be provided in order to have a bearing surface for the upper elastic element or for the upper region of the single-part elastic element. However, in comparison to a cylindrical diffuser, a diffuser of this type is more difficult to produce and, in addition, the airbag loses structural space. A further disadvantage is that the annular elastic elements cannot be fixed in place.

SUMMARY

An object of the present invention is to design an easily fittable, elastic mounting of the gas generator in such a manner that it can be used irrespective of the shape of the diffuser or of the shape of the housing surrounding the gas generator.

According to an embodiment of the present invention, an airbag module having an elastically mounted gas generator is provided. The airbag module includes an airbag and a covering facing a passenger compartment. The gas generator is mounted by means of elastic subassembly, which has a retaining element running obliquely upward, i.e., obliquely in the direction of the covering. The elastic subassembly further includes a retaining element running obliquely downward, i.e., obliquely in the direction opposed to the aforementioned direction. The two retaining elements are fastened to the gas generator or to a section of the airbag module that is assigned to the gas generator and rest on the respectively other subassembly, i.e., the associated section of the airbag module or on the gas generator.

The advantage of this arrangement is that it can be used in the case of a conventional diffuser having a cylindrical wall, with it being ensured that it can be fitted easily. This diffuser can be produced more easily than a step-shaped diffuser. The airbag does not lose any structural space or folds. This arrangement also permits the airbag module to be constructed in a flat manner.

A plurality of segment-like, elastic subassemblies can be provided which are arranged at the same angular spacing from one another. When a plurality of elastic subassemblies are used, it is preferable to arrange at least three elastic subassemblies.

However, it is possible to provide an annular, elastic subassembly. A design of this type additionally ensures that there is a seal between the gas generator and the surrounding housing, with the result that no gas in the region of the securing of the gas generator can escape from the airbag module.

The retaining elements preferably have a finger-shaped cross section.

In another embodiment of the present invention, the elastic subassembly has the cross-sectional shape of a Y where the obliquely running branches of the Y constitute the retaining elements, which bear by means of the conventionally vertical section of the Y on the gas generator or are fastened to another component of the airbag module.

The elastic subassembly is preferably arranged in the lower part of the gas generator, the lower, conventionally vertical section of the Y running in the plane of a generator carrier or parallel to this plane, an oblique section of the Y being the retaining element which runs obliquely upward, and the other oblique section of the Y being the retaining element which runs obliquely downward. The elastic subassembly thus has a cross section in the form of a horizontal Y.

According to another embodiment of the present invention, the retaining element that runs obliquely upward engages in a depression of the generator carrier, and the retaining element which runs obliquely downward engages in a depression of a retaining plate connected to the generator carrier. In this embodiment, the elastic subassembly is arranged below the diffuser housing, with the result that the latter can be designed irrespective of the fastening of the gas generator.

The elastic subassembly may be fastened to flange connected to the gas generator. This flange may annularly surround the gas generator housing or, if a plurality of segment-shaped, elastic subassemblies are used, corresponding flange segments may also be provided.

The elastic subassembly may include, for example, rubber or silicone and is preferably injection molded onto the gas generator and/or onto the flange connected to the latter.

According to yet another embodiment of the present invention, the elastic subassembly is connected to a generator carrier, and the obliquely running branches of the Y engage in recess on the gas generator. According to this embodiment the elastic subassembly may have a cross section in the form of a horizontal Y.

According to still another embodiment of the present invention, provision is made for retaining element to be provided in the upper and lower regions of the gas generator. In this embodiment, the retaining elements are fastened to the gas generator, with the retaining element arranged in the upper region of the gas generator resting on a housing surrounding the gas generator, and with the retaining element arranged in the lower region of the gas generator resting on the housing and on a retaining plate. In particular, a diffuser housing is provided as the housing. The elastic subassembly is preferably designed in such a manner that it can be pulled over the gas generator. For example, the elastic subassembly may be in the form of a hood in which retaining elements are integrated. This embodiment affords the further advantage of it being possible to design the gas generator without a flange.

Since, in the case of this type of elastic mounting of the gas generator there is no conductive connection between the latter and other vehicle parts, i.e., the gas generator is no longer grounded, a flexible grounding cable is arranged between the gas generator and ground in order to ground it.

DESCRIPTION

FIG. 1illustrates an airbag module1which has a cup-shaped gas generator2, a diffuser housing3with apertures4for the escape of the gas generator gases, an airbag5, and a covering cap6. The gas generator is mounted elastically in the lower section of the airbag module. For this purpose, the gas generator has an annular flange7onto which an annular, elastic subassembly8(FIG. 4) or a plurality of segment-like, elastic subassemblies9(FIG.3), for example made of silicone, may be injection molded. For the fastening of the segment-like, elastic subassemblies, it is possible, instead of the annular flange7, also for flange segments to be arranged in the region of the elastic subassemblies.

The elastic subassemblies have the cross-sectional shape of a generally horizontal Y with an upper retaining element10running obliquely upward, i.e., obliquely in the direction of the covering cap6, and with a lower retaining element11aforementioned direction. The retaining elements have a finger-shaped cross section. The diffuser housing3is fastened to a generator carrier12to which a retaining plate13is fitted from below. All three parts3,12, and13may be connected to one another in one working step by bolts14and nuts15.

As shown inFIG. 2, the generator carrier12has a depression16in which the upper retaining element10engages. The retaining plate13has a depression17in which the lower retaining element11engages. During the installation of the parts3,12, and13, the upper retaining element10is pressed onto the generator carrier12, and the lower retaining element11is pressed onto the retaining plate13, as a result of which a secure, elastic fastening of the gas generator is obtained.

As shown inFIG. 5, according to another embodiment of the present invention, the airbag module may include an elastic subassembly18which is in the form of a hood and is pulled over the gas generator2. The subassembly18includes a section18athat extends under the bottom of the gas generator, securely connecting the subassembly to the gas generator. The subassembly18includes at least one opening19for gases to escape after the gas generator2has been fired. The subassembly18has, in the lower section, a retaining element21which runs or extends obliquely downward, has a finger-like cross section and annularly surrounds the gas generator2. In the upper section, the subassembly18has a retaining element20which runs obliquely upward, has a finger-like cross section and likewise annularly surrounds the gas generator2. Instead of the annular retaining elements20,21, spaced apart segment-like retaining elements may be provided. The spaced apart retaining elements may be spaced at regular intervals around the gas generator2and the subassembly18.FIG. 5also depicts these segment-like retaining elements because the subassembly18has the same cross-section in the region of the spaced apart segments.

As shown inFIG. 5, the retaining elements20,21interact with a retaining plate22and a diffuser housing23, which are connected to each other by bolts24and nuts25. During the installation, the gas generator2, which is provided with the subassembly18, is placed onto the retaining plate22, and then covered by the diffuser housing23. After connection of the diffuser housing23to the retaining plate22, the lower retaining element21is pressed against the plate22and against the side wall26of the diffuser housing23while the upper retaining element20is pressed against the side wall26and the upper wall27of the diffuser housing23. The gas generator2is thus mounted securely and elastically.

According to the embodiment of the present invention shown inFIG. 6, unlike in the preceding exemplary embodiments, the elastic subassemblies are fastened between a generator carrier28and a retaining plate29. Four segment-like, elastic subassemblies are provided, of which two subassemblies30can be seen in FIG.6. The subassemblies have a cross-sectional shape of a horizontal Y. As shown inFIG. 7, each elastic subassembly30has an upper retaining element31orientated obliquely upward and a lower retaining element32orientated obliquely downward. The retaining elements31,32engage in a recess33of a retaining part34fastened to the gas generator2. The elastic subassemblies also have a section35fastened between the generator carrier28and the retaining plate29.

During assembly of the module, the gas generator2together with the elastic subassemblies30is placed onto the retaining plate29. The generator carrier28and the diffuser housing3with the lower section of the airbag5interposed there-between, are then connected to the retaining plate29by screws and nuts (not shown). The elastic subassemblies30are thus anchored fixedly between the generator carrier28and the retaining plate29, and the retaining elements31and32are pressed in the recess33fixedly onto the retaining part34.

The priority document, DE 102 15 330.2, filed Apr. 3, 2002, is incorporated by reference herein in its entirety.