Abstract
It is provided a gas-bag unit for a motor vehicle, having an inflatable gas bag which comprises at least two material layers that are fastened to one another by means of a circumferential seam in such a manner that the at least two material layers surround a gas-bag interior. A first portion of the gas bag is folded down to form a fold in such a manner that a first portion of the circumferential seam, which is located in the first portion of the gas bag, and the first portion of the gas bag are separated from the gas-bag interior by the fold.
Claims
1. A gas-bag unit for a motor vehicle, having an inflatable gas bag which comprises at least two material layers that are fastened to one another by means of a circumferential seam in such a manner that the at least two material layers surround a gas-bag interior, wherein a first portion of the gas bag is folded down to form a fold in such a manner that a first portion of the circumferential seam, which is located in the first portion of the gas bag, and the first portion of the gas bag are separated from the gas-bag interior by the fold.
2. The gas-bag unit according to claim 1, wherein a gas generator is provided and is configured to provide gas for filling the gas bag, wherein the gas generator has at least one outlet opening, through which the gas flows from the gas generator into the gas-bag interior, and wherein the fold is arranged in such a manner in relation to the at least one outlet opening that the gas emerging from the gas generator is directed onto the fold.
3. The gas-bag unit according to claim 2, wherein the at least one outlet opening of the gas generator is oriented in such a manner that the gas emerging from the gas generator is not directed onto the circumferential seam.
4. The gas-bag unit according to claim 1, wherein the fold is formed in the inflated and in the non-inflated state of the gas bag.
5. The gas-bag unit according to claim 2, wherein the first portion of the gas bag cannot be inflated or can only be inflated slightly by the gas flowing from the gas generator.
6. The gas-bag unit according to claim 1, wherein the first portion of the gas bag is fixed in relation to the rest of the gas bag.
7. The gas-bag unit according to claim 1, wherein the first portion of the gas bag comprises a portion of each of the at least two material layers, which are fastened to one another by the first portion of the circumferential seam.
8. The gas-bag unit according to claim 1, wherein a plurality of first portions of the gas bag are folded down to form one or more fold(s).
9. The gas-bag unit according to claim 1, wherein a gas-conducting device is provided and is configured to conduct gas for filling the gas bag into the gas-bag interior, wherein the gas-conducting apparatus is formed in particular as a hose feed.
10. A vehicle occupant restraint system having a gas-bag unit which comprises an inflatable gas bag, wherein the gas-bag unit is a gas-bag unit according to claim 1.
11. An apparatus for changing a seat contour of a vehicle seat having a gas-bag unit which comprises an inflatable gas bag, wherein the gas-bag unit is a gas-bag unit according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention will be explained in more detail hereinbelow on the basis of exemplary embodiments and with reference to the figures.
[0016] FIG. 1 shows a plan view onto a gas-bag unit according to one embodiment of the invention.
[0017] FIG. 2 shows a section of a side view of the gas-bag unit according to the embodiment of the invention shown in FIG. 1.
DETAILED DESCRIPTION
[0018] FIG. 1 shows a plan view of a gas-bag unit 1 for an airbag module. The gas-bag unit 1 comprises an inflatable gas bag 11, which comprises two material layers of a woven fabric. FIG. 1 shows the gas bag 11 in the non-inflated state. The two material layers 111 are fastened to one another by means of a circumferential seam 112 in the marginal region of the material layers 111. The material layers 111 are formed from a woven fabric portion which is turned down. Along the free circumferential edge (outside the circumferential edge formed by the turning-down), the material layers 111 are fastened to one another by the circumferential seam 112. Here, the circumferential seam 112 is a sewn seam. Alternatively, two separate material layers may be provided, these being fastened to one another along their entire circumferential edge by a circumferential seam (in the form of a sewn seam). The two material layers enclose a gas-bag interior. A gas generator 12 having at least one outlet opening 121 is provided, a gas stream 122 flowing through said outlet opening into the gas-bag interior 113 and inflating the latter. Here, the gas stream 122 is directed onto a fold 114. The fold is formed by folding down a first portion 11a of the gas bag 11. In this case, the first portion 11a of the gas bag 11 comprises in each case a portion of the two material layers 111. The material layers 111 of the first portion 11a are held together by a first portion 112a of the circumferential seam 112. The fold 114 separates the first portion 112a of the circumferential seam 112, which is located in the first portion 11a of the gas bag 11, and the first portion 11a of the gas bag 11 from the gas-bag interior 113. The fold 114 makes it possible to prevent the gas stream 122 from impinging directly on the first portion 112a of the circumferential seam 112 (and thus on the region which is originally at risk in terms of strength), and from damaging the circumferential seam under certain circumstances by virtue of it impulse and/or its temperature. Instead, the gas stream 122 impinges on the fold 114, the latter protecting the first portion 112a of the circumferential seam 112 located therebehind (as considered in the direction of flow of the gas stream) by virtue of the fact that the thermal and/or mechanical energy of the gas stream is distributed over the woven fabric and the rest of the circumferential seam outside the first portion 112a of the circumferential seam 112. The fold 114 moreover prevents the first portion 11a of the gas bag 11 from being inflated, and the material layers 111 from being displaced significantly in said first portion 11a with respect to one another and with respect to the first portion 112a of the circumferential seam. The fold 114 thus separates the inflatable or inflated gas-bag interior 113 from the non-inflatable first portion 11a of the gas bag 11. The gas-bag interior should be defined only as being that part which is inflatable or inflated by gas. By way of example, the size of the fold 114 can vary depending on the size of the gas bag, the way in which the gas stream is directed, or the nature of the gas stream. Therefore, the fold may extend over a few millimetres or over the entire extent of the gas bag along one direction. Similarly, the number of folds 114 formed may vary in order to protect further portions of the gas bag which are subjected to mechanical loading. That is to say that one or more folds 114 may be present for each gas bag 11, it also being possible for these to overlap or intersect for example. The folds 114 can thus be arranged in such a manner that they substantially determine the shape of the circumferential edge of the gas bag 11 and therefore the design of the gas bag 11. FIG. 2 shows a section of the gas-bag unit shown in FIG. 1 in an inflated state, the gas generator not being arranged in the section depicted.
[0019] The gas-bag unit shown in FIGS. 1 and 2 is similarly suitable for an apparatus for changing a seat contour of a vehicle seat. Instead of a gas generator, the gas-bag unit for an apparatus for changing a seat contour of a vehicle seat may have a gas-conducting device (not shown), this being designed to conduct gas into the gas-bag interior. The gas- conducting device can be connected to a gas source arranged outside the gas bag. By way of example, the gas-conducting device can be configured in the form of a hose feed protruding through an opening of the gas bag into the gas-bag interior. Furthermore, the material layers can be manufactured from a plastics material, the circumferential seam being a welded seam for example. The fold 114 protects the first portion 112a of the circumferential seam 112 against permanent movement of the material layers and the associated gradual destruction (material cracking, seam fracture) of the first portion 112a of the circumferential seam.
