Gas bag for a vehicle occupant restraint system

[0001] This invention relates to a gas bag for a vehicle occupant restraint system, which gas bag can be transferred from a folded condition into a deployed condition and comprises a first chamber which has an inflation opening, and a second chamber which is in flow connection with the first chamber. The invention also relates to an assembly consisting of such gas bag and a vehicle body.

[0002] Two-chamber gas bags of this type are known in a wide variety of embodiments. The first chamber can for instance be used as body chamber which restrains the torso of a vehicle occupant, and the second chamber can be allocated to other parts of the body.

[0003] The object of the invention consists in further developing a known two-chamber gas bag in such a manner that the restraining effect provided for the vehicle occupant is improved.

[0004] According to the invention there is provided a gas bag for a vehicle occupant restraint system, which gas bag can be transferred from a folded condition into a deployed condition and comprises a first chamber which has an inflation opening, and a second chamber which is in flow connection with the first chamber. The first chamber is generally elongate in the deployed condition and the second chamber is connected with the first chamber at a side face of the first chamber, so that the gas bag is asymmetrical. A limiting strap is provided which extends across an outside of the second chamber and across part of an outside of the first chamber. The second chamber, which is asymmetrically arranged as “ear” on the first chamber, offers a restraining effect especially for one side of the head of a vehicle occupant. The limiting strap, which extends approximately transverse to the longitudinal direction of the second chamber and, in the deployed condition of the gas bag, at least partly at a distance from the first chamber, forms a special impact surface for the head of the vehicle occupant, which after the impact of the head of the vehicle occupant draws the second chamber towards the head of this vehicle occupant.

[0005] The gas bag according to the invention is arranged in a vehicle in such a manner that the second chamber faces an A-pillar of the vehicle body. In the case of a driver gas bag for a vehicle with the steering wheel on the left side, the second chamber, as seen in direction of travel, is disposed on the left side of the gas bag, and in the case of a passenger gas bag, the second chamber is disposed on the right side of the gas bag. With this arrangement, the forces acting on the vehicle occupant in the case of an accident have been taken into account, in particular the movements resulting from the use of a usual 3-point safety belt and the movements resulting from a possible rotation of the vehicle during an accident. The safety belt extends at an angle from that shoulder of the vehicle occupant which faces the outside of the vehicle, and across the chest towards the pelvis. This results in a very large restraining effect for the shoulder facing the outer side of the vehicle, whereas the shoulder lying on the inner side is restrained less. In the case of a strong deceleration, the upper region of the chest experiences a movement which is slightly directed towards the outside of the vehicle. The result is that the head of the vehicle occupant tends to be displaced towards the A-pillar. The second chamber disposed on the outside of the first chamber of the gas bag according to the invention counteracts such displacement in a particularly advantageous manner.

[0006] Advantageous aspects of the invention can be taken from the sub-claims.

[0010] The gas bag 10 has a first chamber 12 and a second chamber 14. The first chamber generally is elongate and, as can be seen in particular in FIG. 2, slightly waisted, and the second chamber 14 is laterally attached to the first chamber 12 in the manner of an ear. With respect to the mounting position of the deployed gas bag shown in FIG. 2, the second chamber is placed against the upper end of the first chamber. There is a flow connection between the first chamber 12 and the second chamber 14 of the gas bag, so that compressed gas, which flows into the first chamber through an inlet opening 16, in part also flows into the second chamber and deploys the same.

[0011] In FIG. 2, the gas bag is shown installed in a vehicle, of which segments of a part of a dashboard 20, a part of a vehicle door 22 and an A-pillar 24 are shown here. The gas bag 10 is part of a driver gas bag module, which is mounted in a steering wheel 26. To ensure that in the deployed condition the gas bag is always positioned in the same orientation relative to the driver to be restrained, independent of a rotation of the steering wheel, the gas bag module is rotatably mounted on the steering wheel 26 such that the longitudinal direction of the first chamber of the deployed gas bag always extends vertically. Such gas bag module is described in the German Utility Model 297 02 441, to the disclosure of which reference is made in this connection.

[0012] The connecting line 30 between the first chamber 12 of the gas bag and the second chamber is designed like a hinge, so that the second chamber 14 can be folded down with respect to the first chamber to a limited extent. On the outside of the gas bag a limiting strap 32 is mounted, which is connected with the second chamber 14 on the outside thereof, extends across the side of the second chamber facing the driver and across part of the surface of the first chamber 12, and is sewn to the first chamber on the outside thereof. The limiting strap 32 is made so short that with the gas bag deployed it draws the second chamber 14 towards the first chamber 12. This can be clearly seen in FIG. 3; the limiting strap 32 is so short that the chamber 14 is slightly folded down and in the vicinity of the transition from the second chamber 14 to the first chamber 12 the limiting strap 32 extends at a distance from the wall of the gas bag.

[0013] The limiting strap 32 acts as an intercepting or impact surface for the head of a vehicle occupant, and during the impact of the head of the vehicle occupant onto the limiting strap 32, the second chamber is drawn even more towards the middle of the gas bag and the first chamber. There is thus obtained an improved support for the head of the vehicle occupant on the side facing the A-pillar 24, so that a contact between A-pillar and head of the vehicle occupant is reliably prevented.

[0014] In an alternative embodiment, the gas bag can also be used on the passenger side. In this case, the second chamber 14 is mounted mirror-inverted at the first chamber 12, so that it in turn lies on that side of the gas bag which faces the outside of the vehicle body and thus the A-pillar. In such passenger gas bag module, the attachment of the gas bag module is simplified, as the module can be mounted in the dashboard so as to be stationary.

[0015] In vehicles with the steering wheel on the right side of the vehicle, the gas bag is of course designed mirror-inverted with respect to the above embodiments, i.e. on the driver side with the second chamber 14 on the right side of the gas bag and on the passenger side with the second chamber on the left side of the gas bag.