Airbag module with horn switch

p0001The invention relates to a arranged on the steering wheel of a motor vehicle airbag module with a horn switch designed as a pressure-sensitive switching film.

p0002An air bag device having a pressure-sensitive horn switch is known from DE 43 10 625th In this known device is the horn switch part of a pad assembly, consisting of a top layer of an elastic synthetic resin, a rigid insert which is embedded in the side wall of the cushion, a composite of sheet metal switch, wherein the metal sheets have a stabilizing shape and to the rigid insert are supported. The contact tongues of the horn switch are located between the elastic covering layer and the package of the folded air bag, which rests in turn on the diffuser of the gas generator. The height of the package of the folded airbag can not be made uniform in mass production. Rather, it must be expected with a significant tolerance for the height dimension of this package. Since it but support the contact tongues of the horn switch, the actuating travel of the horn switch is dependent on the real height of the airbag package and thus also subject within a series with the corresponding large tolerance. This may result in that within a group of motor vehicles having the horn actuation very different distances. Moreover, the construction of such a device is complicated and therefore expensive.

p0003It is also known, as described in the aforementioned publication with the prior art to incorporate the horn switch as a switching film in a top layer of the airbag cover or to be located between a top layer and a liner. However, these embodiments have the disadvantage that a definite shift force is hardly feasible, as it lacks a uniform support of the pliable sheet switch due to the very different high airbag package.

p0004The object of the invention is to provide an arranged on the steering wheel of a motor vehicle airbag module with a horn switch, which is designed as a pressure-sensitive switching film and in which the actuating and the shift force is independent of the Pack-tolerance of the airbag consistently.

p0005This object is achieved by the characterizing features of claim 1.

p0006Since the thickness of the bag material is unique and based on a situation is closely tolerated, and the switching path for operating the horn switch can be set accurately and repeatably within a series. The horn switch can thus be easily formed by a switching film which responds with a defined pressure and low switching travel.

p0007Advantageous embodiments are given by the other claims.

p0008Two embodiments of the invention are described below with reference to a drawing. The single figure shows an air bag module mountable on a steering wheel, in section, the left and right of the center line of a separate embodiment.

p0009In a housing 1 of the airbag module a gas generator 2 is fixed which carries at its upper side, a cap-shaped diffuser third A ring around the gas generator 2 and diffuser 3, a folded air bag 4 is arranged, which is fastened with its rim 5 in a conventional manner at the bottom of the housing first A single layer 6 of the airbag 4 forms the bottom thereof and extends over the gas generator 2 and thus through the diffuser 3 time. A cap 7 with elastic wall 8 covers the airbag module to the vehicle interior from back. In the elastic wall 8 of a pressure-sensitive switching film 9 is incorporated and connected by means of not shown electrical wires to a voltage source and to a horn such that when pressure on the switching film 9, a contact is closed and current flows from the voltage source to the horn flows.

p0010In the embodiment shown in the drawing to the left of the center line 8 of the cap 7 supporting ribs 10 are attached to the underside of the elastic wall, which extend to near the boundary of the diffuser third Between the ends of the support ribs 10 and the diffuser 3 to the bottom of the air bag 4 forming single layer is 6. The upper lid of the diffuser 3 therefore acts as a supporting body 11, on which at an outer pressure on the outer side of the elastic wall 8, namely supported at a horn actuation, the inner side on the support ribs 10th The single layer 6 of the air bag 4 between the supporting ribs 10 and the supporting body 11 does not distort the predetermined switching travel of the horn switch. The space between the support ribs 10 is filled with a foam material 12, so that, in a head impact on the wall 8 in the case of a crash, the required power consumption is ensured.

p0011A second embodiment of the invention is shown in the drawing on the right of the center line, wherein like parts are provided with the same reference numerals as the previously described embodiment.

p0012The bottom of the airbag 4 'is as a single layer 6' directly along under the elastic wall 8 'of the cap 7'. There is a rib body 13, which is fixed with resilient hooks 14 on the support body 3 between a position 6 'and the supporting body formed by the diffuser 3 eleventh The fin body 13 has supporting ribs 10 ', which are supported on the supporting body 11th The space between the supporting ribs 10 'is provided with a foam material 12' filled in, the 'attenuates a head impact with the airbag module, together with the support ribs 10th Such a design can with respect to the first-described type then have advantages, when the hardness of the support ribs of the elastic material of the wall 8 is not sufficient to absorb the kinetic energy of an impacting body portion by deformation energy.