FRONT AIRBAG FOR A VECHILE OCCUPANT, VEHICLE OCCUPANT PROTECTION SYSTEM, AND METHOD FOR OPERATING A VEHICLE OCCUPANT PROTECTION SYSTEM

Abstract

A front airbag (10) for the protection of a vehicle occupant (12) in a vehicle which is specifically a passenger airbag for the protection of a passenger, in the installed and inflated state includes a contact wall (20) facing the vehicle occupant (12) and an opposite rear wall (22) as well as a first sidewall (24) facing the vehicle center as seen by the vehicle occupant (12) and an opposite second sidewall (26). The airbag (10) further includes a limiting device which, in the inflated state of the airbag (10), prevents the first sidewall (24) from further deploying so that the airbag (10) takes a first volume. The limiting device can be influenced when the head (14) of the vehicle occupant (12) contacts the airbag (10) such that it allows the first sidewall (24) to further deploy so that the airbag (10) takes a second volume larger as compared to the first volume. Accordingly, at least a major part of the volume of the airbag (10) increases in the direction of the vehicle center as seen by the vehicle occupant (12).

Claims

1-11. (canceled)

12. A front airbag for the protection of a vehicle occupant in a vehicle, specifically a passenger airbag for the protection of a passenger, wherein the airbag in the installed and inflated state includes a contact wall facing the vehicle occupant and an opposite rear wall as well as a first sidewall facing the vehicle center as seen by the vehicle occupant and an opposite second sidewall, wherein the airbag includes a limiting device which, in the inflated state of the airbag, prevents the first sidewall from further deploying so that the airbag takes a first volume, wherein the limiting device can be influenced when the head of the vehicle occupant contacts the airbag such that it allows the first sidewall to further deploy so that the airbag takes a second volume larger as compared to the first volume, wherein at least a major part of the volume of the airbag increases in the direction of the vehicle center as seen by the vehicle occupant.

13. The front airbag according to claim 12, wherein the second volume is about 20% larger than the first volume.

14. The front airbag according to claim 12, wherein the limiting device comprises a tether.

15. The front airbag according to claim 12, wherein the tether is connected, on the one hand, to the first sidewall and is coupled, on the other hand, to an activatable release unit.

16. The front airbag according to claim 12, wherein the limiting device includes a fold formed in the first sidewall which is temporarily secured.

17. The front airbag according to claim 12, wherein the limiting device includes a fold formed in the first sidewall which is temporarily secured by a tear seam or an adhesive.

18. The front airbag according to claim 16, wherein the temporary securing of the fold is designed so that in the inflated state of the airbag it withstands the internal pressure.

19. The front airbag according to claim 16, wherein for forming the fold a textile cutting is provided in addition to the first sidewall.

20. The front airbag according to claim 16, wherein the fold or the textile cutting, respectively, is coupled to an activatable release unit which can release the fold from the inner face of the sidewall.

21. A vehicle occupant protection system, comprising an airbag according to claim 12, a detection device, a control unit coupled to the detection device, and a release unit coupled to the control unit, the detection device being arranged so that after an oblique collision it detects a contact of the head of the vehicle occupant with the airbag and signals the contact to the control unit, wherein the control unit is arranged so that it then activates the release unit, and wherein the release unit is arranged to influence the limiting device such that the latter initiates the further deployment of the first sidewall.

22. The vehicle occupant protection system according to claim 12, wherein a single-stage inflator is provided to inflate the airbag.

23. A method of operating a vehicle occupant protection system according to claim 12, comprising the following steps of: detecting an oblique collision and a contact of the head of the vehicle occupant with the airbag caused by the oblique collision by way of the detection device; signaling the contact to the control unit; activating the release unit by the control unit; and influencing the limiting device of the airbag by the release unit such that the first sidewall further deploys.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0025] Further features and advantages of the invention will be evident from the following description and the attached drawings which are referred to, and wherein:

[0026] FIG. 1a shows a top view onto an inflated front airbag according to the invention as part of a vehicle occupant protection system according to the invention in the installed and inflated state as set forth in a first embodiment;

[0027] FIG. 1b shows the airbag of FIG. 1a after the impact of the vehicle occupant;

[0028] FIG. 2a shows a top view onto an inflated front airbag according to the invention as part of a vehicle occupant protection system according to the invention in the installed and inflated state as set forth in a second embodiment;

[0029] FIG. 2b shows the airbag of FIG. 2a just before the impact of the vehicle occupant; and

[0030] FIG. 2c shows the airbag of FIG. 2a after the impact of the vehicle occupant.

DESCRIPTION

[0031] FIG. 1a illustrates a first embodiment of a front airbag 10, more precisely a front passenger airbag, in a vehicle in the installed and inflated state. The vehicle occupant 12 (passenger) to be protected by the airbag is shown with his/her head 14 and his/her torso 16.

[0032] The airbag 10 is part of an airbag module which in turn is part of a vehicle occupant protection system. The airbag module comprises a module case in which, apart from the airbag 10, an inflator is accommodated. The inflator is a single-stage or multi-stage inflator having one or more discharge openings. When the inflator fills the initially folded airbag 10 with gas, the airbag 10 deploys out of the module case toward the vehicle occupant 12. Alternatively, a filling by plural inflators is also possible.

[0033] The airbag 10 has an outer wall 18 which can be divided into plural portions. The area facing the vehicle occupant 12 in the inflated state is referred to as contact wall 20 and the area opposite to the contact wall 20 which is fastened on the module side is referred to as rear wall 22. The areas between the contact wall 20 and the rear wall 22 are referred to as sidewalls 24, 26.

[0034] Hereinafter, the longitudinal direction of the vehicle in the driving direction is referred to as x-direction, the transverse direction of the vehicle perpendicular thereto in the direction of the vehicle center as seen by the passenger is referred to as y-direction, and the vertical direction of the vehicle perpendicular to the x- and y-directions and facing upwards is referred to as z-direction.

[0035] In the situation illustrated in FIG. 1a just after an oblique collision, the airbag 10 is inflated, to be sure, but not completely deployed. A limiting device prevents the airbag 10, specifically the first sidewall 24 thereof which, as seen by the vehicle occupant 12, faces the vehicle center in the y-direction, from completely deploying.

[0036] Here, the limiting device comprises a (symbolized) tether 28 which may be arranged outside or inside of the airbag 10. A first end of the tether 28 is connected to the first sidewall 24, while the second end or a central portion of the tether 28 is coupled to an activatable release unit (tether activation unit, TAU). The release unit is connected to a control unit of the vehicle occupant protection system which is also connected to a detection device capable of detecting the contact of the head 14 of the vehicle occupant 12 with the airbag 10 as a result of an oblique collision.

[0037] As soon as the detection device signals the control unit that the head 14 of the vehicle occupant 12 impacts on the contact wall 20 of the airbag 10, the tether 28 is released by the release unit so that the airbag 10 deploys completely, as illustrated in FIG. 1b. Accordingly, in particular the effective surface of the first sidewall 24 is increased.

[0038] The release of the tether 28 causes the volume of the airbag 10 to suddenly increase by about 20%. Accordingly, the pressure inside the airbag 10 is significantly reduced. The lower pressure of the airbag 10 allows, in contrast to a bulging airbag, the head 14 of the vehicle occupant 12 to penetrate the airbag 10 relatively unhindered particularly in the x-direction, without being allowed to rotate excessively about the z-axis, which would be basically possible in a bulging airbag due to the strong restraining effect on the contact wall 20. Therefore, despite the oblique collision, only a low angular acceleration is imparted to the head 14 so that the risk of brain lesion of the vehicle occupant 12 is relatively small.

[0039] In FIGS. 2a to 2c, a second embodiment of the airbag 10 is shown which offers a similar protective effect. In this embodiment, too, the deployment of the airbag 10 is initially restricted by a limiting device. As illustrated in FIG. 2a, a part of the first sidewall 24 which, as seen by the vehicle occupant 12, faces the vehicle center in the y-direction is not fully deployed before the impact of the vehicle occupant 12.

[0040] Here, the first sidewall 24 includes a (symbolized) fold 30 which is temporarily secured with the aid of a tear seam or an adhesive or the like and is retained in the initially inflated state of the airbag 10, i.e., before the impact of the vehicle occupant 12. The fold 30 may also formed by means of an additional (separate) textile cutting.

[0041] The fold 30 or the textile cutting, respectively, is coupled to a (symbolized) pyrotechnical release unit 32 which is adapted to cancel the temporary securing and to cause the fold 30 on the first sidewall 24 to unfold. As in the first embodiment, the release unit 32 is connected to a control unit of the vehicle occupant protection system. This is also applicable to a detection device.

[0042] The detection device signals the control unit that the head 14 of the vehicle occupant 12 has impacted on the airbag 10 (FIG. 2b), whereupon the control unit activates the release unit. FIG. 2c illustrates in which way the airbag deployment changes as soon as the fold 30 is released. The volume of the airbag 10 increases suddenly by about 20%, causing the pressure inside the airbag 10 to drop abruptly. Similar to FIG. 1b, also in this case it is clearly visible that after release of the fold 30 the airbag 10 expands particularly in the y-direction.

[0043] As in the first embodiment, the abrupt drop of pressure inside the airbag 10 results in the head 14 of the vehicle occupant 12 penetrating the airbag 10 relatively unhindered in the x-direction. In addition, the additional deployment of the airbag 10 in the y-direction which is adapted in time to the impact of the vehicle occupant 12 ensures that a torque counteracting the angular acceleration of the head 14 about the z-axis induced by the oblique collision is imparted to the head 14 of the occupant with respect to the z-direction. Thus, the risk of brain lesion of the vehicle occupant 12 is comparatively small.

LIST OF REFERENCE NUMERALS

[0044] 10 airbag [0045] 12 vehicle occupant [0046] 14 head [0047] 16 torso [0048] 18 outer wall [0049] 20 contact wall [0050] 22 rear wall [0051] 24 sidewall [0052] 26 sidewall [0053] 28 tether [0054] 30 fold [0055] 32 release unit