US 20020005634 A1
A gas bag module comprises a gas bag, a first ejection channel, in which part of the gas bag is located, and a flexible cover surrounding the gas bag in areas which are not located within the ejection channel. The cover is provided with a tearing line which allows the gas bag to emerge from the cover.
1. A gab bag module comprising a gas bag, a first ejection channel, in which part of said gas bag is located, and a flexible cover surrounding said gas bag in areas which are not located within said ejection channel, said cover being provided with a tearing line which allows said gas bag to emerge from said cover.
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 Conventional gas bag modules comprise a gas bag, at least a first ejection channel, in which part of the gas bag is located, and in some cases a second ejection channel, which is separated from the first ejection channel by a space and in which another part of the gas bag is located. The gas bag of such a gas bag module serves to provide protection for a vehicle occupant, especially in the case of a side-impact collision. For this purpose, the gas bag is unfolded by means of compressed gas that flows into the gas bag after a gas generator has been activated. The ejection channel serves to receive the gas bag before its activation and to influence the unfolding process and the unfolding direction during the activation.
 Conventional gas bag modules for a side-impact collision extend from the A-column of the vehicle to the C-column In this manner, the passengers in the front seat of the car as well as those in the back seat can be protected in case of a side-impact collision. As a consequence, the gas bag module itself is relatively long, up to about 2.5 meters, so that handling problems arise before the assembly. In order to facilitate the handling, two separate ejection channels may be provided, one of which is mounted later, for example, onto the A-column and the other onto the roof edge of the vehicle. During the transportation of the gas bag module, the two ejection channels, along with the gas bag that has already been placed in them, can be folded together from their fully extended arrangement, so that they lie on each other in a space-saving manner. As an alternative to an embodiment with two ejection channels, a single ejection channel may be used with a length which is considerably smaller than the length of the gas bag. The gas bag then protrudes from either one end or from both ends of the ejection channel.
 A problematic aspect here is that the gas bag, can be damaged both during transportation as such and also by the folding in areas outside the ejection channel or between the two ejection channels.
 The objective of the invention is to prevent damage to the gas bag in the area between the two ejection channels.
 For this purpose, a gas bag module is provided which comprises a gas bag, a first ejection channel, in which part of the gas bag is located, and a flexible cover surrounding the gas bag in areas which are not located within the ejection channel. The cover is provided with a tearing line which allows the gas bag to emerge from the cover. The invention is based on the general notion of using a cover for the parts of the gas bag that are exposed during transportation of the gas bag and assembly in the vehicle, for example, because they protrude from a housing part of the gas bag module and consequently can easily be damaged. The cover especially offers mechanical protection for the gas bag that is exposed in the area between the ejection channels in case two ejection channels are used, so that damage during transportation or due to creasing of the gas bag in this area can be reliably prevented. The material for the cover can fundamentally be any flexible material that offers an adequate mechanical protection for the gas bag. An especially suited material is Tyvek.
 Advantageous embodiments of the invention are defined in the sub-claims.
 The invention is described below with reference to a preferred embodiment that is shown in the single appended drawing. This drawing shows a gas bag module according to the invention in a perspective view.
 The gas bag module 5 has a gas bag that is folded up in two ejection channels 12, 14. Each ejection channel has an outlet opening 16 through which the gas bag can emerge from the ejection channels when it is unfolded. In order to unfold, compressed gas flows into it via a gas lance 18 that is shown here in schematic form.
 A cover 20 is provided that is attached to the two ejection channels 12, 14 and that extends over the space located between them so that the gas bag extending through the space from one ejection channel to the other ejection channel is covered. The cover consists of a generally square piece of material that is folded in such a way as to form a tube. Each ejection channel 12, 14 is provided with a projection 22 that protrudes through the corresponding openings of the cover 20. Moreover, adhesive sites 24 are provided on which the cover is glued together and attached to the corresponding ejection channel.
 On the cover 20, there is a tear line 16 in the form of a perforated line that extends into the extension of the outlet opening 16. The tear line 26 is configured in such a way that it is destroyed when the gas bag unfolds, so that the gas bag can unfold freely.
 The term tear line is to be understood to designate any arrangement which allows the gas bag to escape from the cover when the gas bag is unfolded. Instead of a perforated line, the tear line may be formed from a tearing seam, an adhesive connection or any other suitable connection between two plies of the cover.
 It is to be noted that the cover may be used also for embodiments of the gas bag module in which a single ejection channel is provided, from which the gas bag protrudes at one end or at both ends. The cover is then attached at one of its ends only and covers the gas bag in the areas outside the ejection channel.