Gas bag module

#This invention relates to a gas bag module comprising a gas bag.

#Known gas bags have a front wall for the impact of the occupant and an indentation starting from the front wall, which indentation is formed in that a center portion of the gas bag wall is prevented from moving freely during inflation and is restrained, the gas bag having an annular chamber to be filled with gas and provided around the indentation. In such ring-shaped gas bags, the center portion which in a conventional gas bag is presented to the occupant, is prevented from being inflated and from moving towards the occupant in that it remains attached to the module. In this arrangement, restraint is effected via the ring-shaped front wall around the indentation. The indentation is to be as small as possible so as to help the head of the occupant to be intercepted as safe as possible.

#The invention provides a gas bag module in which the indentation is closed at least in part, preferably completely. This is achieved in a gas bag module comprising a gas bag, an outer contour of the gas bag being defined by a gas bag wall which has a front wall for the impact of an occupant and an indentation starting from the front wall. The indentation is formed in that a center portion of the gas bag wall is prevented from freely moving during inflation and is restrained. The gas bag has a ring-shaped chamber to be filled with gas and extends around the indentation. Arranged in the indentation is at least one limiting strap which extends along the indentation and has an end pointing out of the indentation and, related to an inflated condition of the gas bag, is attached to the gas bag wall at least at the end pointing out of the indentation. By means of the at least one limiting strap arranged in the indentation, the indentation is preferably completely closed in the region of that end of the limiting strap which points out of the indentation. The gas bag itself preferably is a front gas bag accommodated in the steering wheel or in the dashboard, which front gas bag is inflated in the case of a frontal impact.

#FIG. 1 shows a cross-sectional view of a gas bag module according to the invention with an almost completely inflated gas bag,

#FIG. 2 shows a cross-sectional view of the gas bag module as shown in FIG. 1 with completely inflated gas bag,

#FIG. 3 shows a cross-sectional view of another embodiment, in which the gas bag is not yet completely inflated,

#FIG. 1 represents a gas bag module accommodated in the steering wheel, which gas bag module comprises a gas bag 3, a gas generator 5 and a module housing 7 with a module cover 9. The gas generator 5 is surrounded by a pot- or bell-shaped diffuser 10, which has been put over the gas generator 5 from above and is attached to the module, more precisely to the module housing 7. Instead of the diffuser 10 another holding member surrounding the gas generator 5 may, however, also be provided.

#The gas bag has a gas bag wall defining the outer contour of the gas bag which wall has several fabric parts. The gas bag has a front wall 11 which faces the occupant in the inflated condition and restrains the same. Moreover, a rear wall 12 is provided. The front wall 11 and the rear wall 12 consist of ring-shaped fabric parts which are connected with each other at a peripheral seam 13. In the middle of the gas bag, i.e. in the center, an indentation 17 open towards the top extends from the front wall 11 towards the gas generator 5. The indentation 17 which is not inflated by gas of the gas generator, is formed in that a portion of the gas bag wall, subsequently referred to as center portion 16, is prevented from an unrestricted, preferably from any kind of movement out of the module in the case of restraint. As a result, a ring-shaped chamber 18 to be inflated and to be filled with gas is obtained.

#The module cover has a disk-shaped middle part 100 (see FIGS. 3 and 4), which lies above the center portion 16 and is permanently attached to the diffuser 10 and in contrast to a ring-shaped flap is not even folded to the outside when the module is opened. The center portion 16 is also permanently attached to the diffuser 10 via the attachment of the middle part 100. Alternatively, the diffuser 10 and the middle part 100 might be omitted and the center portion 16 might directly be attached to the gas generator 5.