The present invention relates to an airbag module for a motor vehicle comprising an inflatable airbag, the airbag having at least one flow opening as well as a cover element to alter the flow cross section through the flow opening and/or an airbag shaping element, a retaining portion connected to the cover element or to the airbag shaping element and being initially held in a retained state, and an actuator for releasing the retaining portion.

An airbag module with the above features is known from EP 1 772 323 B l . The retaining portion is held by a hook, which hook can be pivoted by the ignition element in order to release the retaining portion from the hook. According to DE 10 2017 108 176 A1 the retaining portion is held by the actuator directly, wherein for releasing the retaining portion the actuator is driven relatively to the retaining portion.

DE 10 2013 000 142 A1 discloses an airbag module, in which the retaining portion of a retaining strap is fixed to a retaining element initially connected to the housing, wherein the actuator is configured to release the retaining element from the housing. Accordingly, all of the prior art documents require that the actuator moves a retaining element relative to the retaining portion of the retaining strap or to actuate the retaining element directly. Accordingly, the retaining portion is only indirectly released by actuating a retaining element. It is also known that a retaining strap is cut in order to adjust the flow cross section or the airbag shaping element.

Accordingly, it is an object of the present invention to provide an alternative airbag module for releasing the retaining portion.

This object is achieved with an airbag module with the features of the independent claim, wherein preferred embodiments of the airbag module are disclosed in the subclaims and in the whole description, wherein single features of the preferred embodiments can be combined with each other in a technical meaningful manner.

In particular, the object is achieved with an airbag module comprising the above features, wherein in the retained state the retaining portion is held by at least one stationary retaining pin and in that the actuator is arranged in such a way that for releasing the retaining portion the actuator at least indirectly drives the retaining portion along the stationary retaining pin until the retaining portion is released from the retaining pin.

With other words, the present invention suggests that not the retaining element holding the retaining portion is at least indirectly moved relative to the stationary housing in order to release the retaining portion, but that the retaining portion is moved relatively to the stationary retaining pin so that the retaining portion is released.

Preferably, the retaining portion is part of a retaining strap (i.e. the retaining strap is formed by a rope or tether) or connected to the retaining strap, wherein the retaining strap is connected to the cover element or to the airbag shaping element on its one side (end) and has the retaining portion on its other side (end). The retaining portion may be embodied by a loop formed with the retaining strap or by a hole within the retaining strap.

The flow opening may be formed in an outer shell of an airbag, so that by altering the flow cross section the ventilation rate of the airbag can be adapted/adjusted. Alternatively, the flow opening may be embodied in an inner wall of the airbag, which inner wall separates two chambers of the airbag from each other, so that with altering the flow cross section the pressure equalization between the two chambers and thus the shape of the airbag can be adapted/adjusted. For example, the flow opening can be completely closed by the cover element in the retained (initial) state, wherein by releasing the retaining portion the flow cross section is at least partly opened. Alternatively, the flow opening may be opened in the retained state, wherein by releasing the retaining portion the flow opening is at least partly closed. Also, other configurations are possible since the invention is not directed to the embodiment of the flow opening.

The airbag shaping element can be for example embodied as a holding strap, which is secured with its one end to the airbag and therefore limits the unfolding/deployment of the airbag, thereby defining the geometrical shape of the airbag. If the retaining portion connected to the holding strap is released the airbag can continue to unfold (deploy) into a different geometric shape.

The at least one retaining pin is preferably extending in one extension direction and has an arbitrary, but preferably rounded cross section. During deployment of the airbag the retaining portion acts/would act with a force onto the retaining pin, wherein the direction of the force is perpendicular to the extension direction of the retaining pin. In particular, two, three or even more parallel extending retaining pins may be embodied. If desired, the actuator drives/moves the retaining portion along the retaining pin, which (at least after its assembly) is stationary with regard to the vehicle/housing of the airbag module. The actuator moves the retaining portion until the retaining portion is unengaged from the retaining pin, in particular the retaining portion is moved over the free end of the retaining pin.

While it is principally possible that the actuator directly drives the retaining portion, in a preferred embodiment a pushing element is provided, which is driven by the actuator along the retaining pin, so that the pushing element pushes the retaining portion along the retaining pin. Accordingly, in the assembled state the pushing element is arranged between the actuator and the retaining portion, which in turn is engaged with the retaining pin.

In this regard it is preferred, that the pushing element is geometrically adapted to be guided along the at least one retaining pin. For example, a portion of the pushing element may be adapted with its shape to the outer shape of the at least one retaining pin, so that, when the actuator drives the pushing element, the pushing element is guided along the at least one retaining pin. For example, if two parallel retaining pins are embodied, the pushing element may comprise a section, which is arranged in between the two retaining pin.

While it is possible that the pushing element is assembled as an individual part on the at least one retaining pin, in a preferred embodiment the pushing element is assembled in such a way, that it is elastically deflectable along the retaining pin. This way, the pushing element can absorb the kinetic energy of the actuator, while at the same time it is made sure, that the retaining portion is moved along the retaining pin in a prescribed manner. Additionally, after the retaining portion is released from the retaining pin the deflectable pushing element avoids that the actuator is released and may even move the actuator back towards its initial position. In a preferred embodiment, the pushing element is an integral part of an housing of the airbag module, wherein the housing and the pushing element are preferable made of plastic material.

The pushing element may be embodied as integral part of a spring, which itself can be integrally formed with the housing. Alternatively, the pushing element may be a separate part connected for example by a positive locking connection to a spring, which in turn might be embodied integrally with the housing. For example, the pushing element may be arranged on an end of a bendable/elastic section of a spring, which can be integrally formed with the housing.

For example, the spring may comprise an elastic section (bendable or deflectable section), i.e. formed by a meandering section or a spirally shaped section or by an appropriate material.

Additionally or optionally the spring may comprise a rigid rod extending perpendicular to a wall of the housing. The elastic section may either be formed (in particular integrally with the housing) within the plane of a wall of the housing, wherein the rod is connected to the elastic section, or at an end of the rod, wherein the elastic section connects the rod with the pushing element. The spring is embodied in such a way, that after deflection of the pushing element the spring force acts into the direction of the retained (initial) state.

It might also be possible that the elastic section of the spring extends for example from the rod along the front of the free end of the stationary pin.

It is also possible that the spring comprises a separate part, which forms the pushing element and which may be connected to the rod, for example by a positively locking connection. It is also suggested that a securing element is provided, which is arranged in the assembled (retained) state in such a way, that the retaining portion is held by the securing element against unintentional release from the retaining pin. For example, the securing element may be arranged on that side of the retaining portion which faces away from the actuator. Accordingly, in the initial assembled state, the securing element is arranged between the retaining portion and a free end of the retaining pin. This way, it is avoided that the retaining portion is unintentional released after its assembly.

As described for the pushing element, preferably the securing element is geometrically adapted to be guided along the at least one retaining pin, is elastically deflectable along the retaining pin, is integral part of the housing and/or is embodied as part of a spring integrally formed with the housing.

In one embodiment, it is suggested that the pushing element and the securing element are integrally formed in one part and preferable integrally with the housing. In this regard, the pushing element and the securing element may be arranged in a forklike manner, wherein in the initial retained state the retaining portion is arranged between the pushing element and the securing element, wherein the retaining portion is in engagement with the at least one retaining pin at the same time.

Basically, it is possible that the at least one retaining pin is a separate part connected to the housing. But it is also possible that the at least one retaining pin is an integral part of the housing. In a preferred embodiment, the at least one retaining pin is part of a subassembly comprising the actuator, so that the actuator and the at least one retaining pin are mutually mounted on the housing. In this case, the housing may comprise a receiving section in/at which the subassembly can be securely fixed. The at least one retaining pin may be shaped in such a way, that the actuator during its driving movement is guided along the retaining pins.

For assembling the airbag module it is suggested, that in a first step the retaining portion is arranged relative to the pushing element and preferably in between the pushing element and the securing element and that in a second step the subassembly is (or at least the retaining pin) is mounted, whereby the at least one retaining pin is brought into engagement with the retaining portion.

The invention and the technical background are now described with regard to the figures, which show an exemplary embodiment. The figures show schematically

Figure 1 : an exploded and perspective view of a part of an airbag module,

Figure 2: a perspective view of a subassembly of the airbag module, Figure 3 : a top view on the part depicted in figure 1 in the assembled state,

Figure 4: a perspective view of a second embodiment of a part of an airbag module,

Figure 5: a perspective view of a third embodiment of a part of an airbag module,

Figure 6: a perspective view of a fourth embodiment of a part of an airbag module and Figure 7: a perspective view of a fifth embodiment of a part of an airbag module.

In figures 1 and 3 a part of a housing 1 of an airbag module is shown. Furthermore, a subassembly 9 is shown, which is depicted in more detail in figure 2.

As can be seen from figure 2 the subassembly 9 comprises a housing with two retaining pins 5 which extend in an extension direction. Furthermore, a pyrotechnical charge is arranged in the subassembly 9, which can drive an actuator 4.

As can be seen from figure 1 a connector 11 for electrically contacting the pyrotechnical charge can be connected to the subassembly 9.

The housing 1 comprises a receiving section 10, in which the subassembly 9 can be fixedly mounted.

Furthermore, a spring 8 is integrally formed with the housing 1 , wherein the spring 8 is made of a rod 12 and an elastic section 13 and wherein at a free end of the elastic section 13 a pushing element 6 and a securing element 7 is formed. During assembly of the airbag module a retaining portion 3 of a retaining strap 2 is inserted in between the pushing element 6 and the securing element 7. Afterwards, the subassembly 9 is inserted into the receiving section 10, whereby the retaining pins 5 are brought into engagement with the retaining portion 3.

As can be seen from figure 3 the retaining portion 3 is arranged between the pushing element 6 and the securing element 7, while at the same time the retaining pins 5 retain the retaining portion 3 in its position. If the retaining portion 3 is to be released, the actuator 4 is pyrotechnically driven, so that the spring 8 is deflected in such a way, that the pushing element 6 and the securing element 7 are moved along the retaining pins 5, thereby pushing the retaining portion 3 along the retaining pins 5 until the retaining portion 3 is disengaged at the free end of the retaining pins 5 from the retaining pins 5. As the pushing element 6 and the securing element 7 have a protrusion, which extends in between the two retaining pins 5, the pushing element 6 and the securing element 7 are securely guided along the retaining pins 5.

The embodiment shown in figure 4 differs from the embodiment of figures 1 to 3 in that an elastic section 14 of the spring 8 extends from the rod 12 in front of a free end of the stationary retaining pins 5. The pushing element 6 and the securing element 7 are formed at the free end of the elastic section 13.

The embodiment shown in figure 5 differs from the embodiment of figures 1 to 3 in that the spring 8 is formed by an elastic section comprising a meandering section, which is formed integrally with the housing and which is arranged within a plane of a wall of the housing. The rod 12 extends perpendicular to the wall of the housing and is integrally connected to the elastic element 13. The pushing element 6 and the securing element 7 are more or less connected in a rigid manner with the rod 12. When the actuator is released the pushing element 6 and the securing element 7 swivel together with the rod 12, whereby the elastic section 13 is deformed.

The embodiment shown in figure 6 is similar to the embodiment of figure 5 in that the elastic section 13 is formed by a meandering part within a wall of the housing and in that the rod 12 extends from that elastic section 13. But, the pushing element 6 and the securing element 7 are formed on a separate part, which is connected to the rod 12 by a snap fit. The embodiment shown in figure 7 is also similar to the embodiment of figure 5, wherein the elastic section 13 is formed spirally and wherein the rod 12 is integrally connected to the free end of the spirally formed elastic section 13.

Reference signs housing retaining strap retaining portion actuator retaining pin pushing element securing element spring subassembly retaining section connector rod elastic section