AIRBAG OF A VEHICLE OCCUPANT RESTRAINT SYSTEM

Abstract

An airbag of a vehicle occupant restraint system has an actively releasable tether element (14) disposed in an interior (16) of the airbag (10) which is connected, at an airbag-side fixation (18), permanently to the airbag (10) in the region of a contact zone (20) for the occupant, and which comprises a detachable fixing point (22) for the release. The airbag (10) can take up a smaller first filled volume (V.sub.1) in which the tether element (14) and the detachable fixing point (22) are not released, and a larger second filled volume (V.sub.2) in which the tether element (14) is released at the actively detachable fixing point (22). In addition to the tether element (14), a tether element restrainer (26) disposed in the interior (16) of the airbag (10) is provided which acts upon a point of action (28) on a vehicle-side portion (34) of the tether element (14) distant from the airbag-side permanent fixation (18) of the tether element (14) and which is permanently fixed to a coupling point (30) distant from the contact zone (20) so that the vehicle-side portion (34) of the released tether element (14) remains connected fixedly to the vehicle via the tether element restrainer (26).

Claims

1. An airbag of a vehicle occupant restraint system, comprising an actively releasable tether element (14) disposed in an interior (16) of the airbag (10) which is connected, at an airbag-side fixation (18), permanently to the airbag (10) in the region of a contact zone (20) for the occupant, and which for the release comprises a detachable fixing point (22), and wherein the airbag (10) can take up a smaller first filled volume (V.sub.1) in which the tether element (14) and the detachable fixing point (22) are not released, and a larger second filled volume (V.sub.2) in which the tether element (14) is released at the actively detachable fixing point (22), and wherein, in addition to the tether element (14), a tether element restrainer (26) is provided in the interior (16) of the airbag (10), the tether element restrainer (26) acting upon a point of action (28) on a vehicle-side portion (34) of the tether element (14) distant from the airbag-side permanent fixation (18) of the tether element (14) and being permanently fixed, distant from the contact zone (20), to a coupling point (30) so that the vehicle-side portion (34) of the released tether element (14) remains connected fixedly to the vehicle via the tether element restrainer (26) when the second volume is provided.

2. The airbag according to claim 1, wherein the tether element (14) is coupled, at the actively detachable fixing point (22), to an electronically controllable release unit (24) so that the tether element (14) can be optionally released, wherein the tether element (14) is tightly coupled to the release unit (24) when the tether element (14) is not released, and is detached from the release unit (24) when the tether element (14) is released.

3. The airbag according to claim 1, wherein the tether element restrainer (26) has such a large length that it is located, when the airbag (10) takes up the second filled volume (V.sub.2), in the interior (16) of the airbag (10) without tensile stress, but is so short that the point of action (28) of the tether element restrainer (16) on the tether element (14) and/or the vehicle-side portion (34) of the tether element (14) cannot reach the contact zone (20) for the occupant.

4. The airbag according to claim 1, wherein the tether element (14) is tightly fixed to the inside in the region of the contact zone (20) of the airbag (10).

5. The airbag according to claim 1, wherein a vehicle-side end of the tether element restrainer (26) is fixed to the coupling point (30) and wherein the coupling point (30) is located on a wall (19) of the airbag (10).

6. The airbag according to claim 1, wherein the tether element (14) comprises a multi-arm structure (36), wherein plural arms (40) are attached to a respective permanent airbag-side fixation on the airbag wall (19).

7. The airbag according to claim 6, wherein the tether element (14) comprises a connecting element (38) which acts upon the multi-arm structure (36) and on which the actively detachable fixing point (22) of the tether element (14) is provided.

8. The airbag according to claim 1, wherein the point of action (28) of the tether element restrainer (26) also forms the actively detachable fixing point (22) of the tether element (14).

9. The airbag according to claim 1, wherein the tether element restrainer (26) is a component merging integrally into the tether element (14) at the actively detachable fixing point (22) and, thus, is an extension of the tether element (14).

10. The airbag according to claim 1, wherein the tether element restrainer (26) is provided as a component additional to the tether element (14) and wherein the point of action (28) of the tether element restrainer (26) is disposed on the tether element (14) distant from the actively detachable fixing point (22).

11. The airbag according to claim 1, wherein the airbag (10) is a driver airbag or a passenger airbag.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the following, the invention shall be illustrated in detail based on plural embodiments with reference to the attached figures, wherein:

[0041] FIG. 1 shows a schematic sectional view of an airbag according to the invention as set forth in a first embodiment which is inflated to a first fillable volume;

[0042] FIG. 2 shows the airbag of FIG. 1 which is inflated to a second fillable volume;

[0043] FIG. 3 shows a schematic sectional view of an airbag according to the invention inflated to a second fillable volume as set forth in a second embodiment; and

[0044] FIG. 4 shows a schematic sectional view of an airbag according to the invention inflated to a second fillable volume as set forth in a third embodiment.

DESCRIPTION

[0045] For better clarity, in the following the same reference symbols will be used for identical or similar features for all embodiments.

[0046] FIG. 1 illustrates an airbag 10 of a vehicle occupant restraint system not shown in detail which is a passenger airbag for a passenger car in this case. The airbag 10 could also be any other airbag for any suitable vehicle, however.

[0047] Via an inflator 12 connected to an inflation mouth (not shown) of the airbag 10, in a situation of restraint filling gas is introduced into the airbag 10 so that the latter is inflated from its state initially folded in an airbag module 13 (not shown), the airbag 10 exiting into a vehicle interior and then being located between a dashboard 15 and a windscreen 17 in an inflated state.

[0048] The airbag 10 can take up two different defined restraining states, wherein it is inflated either to a smaller first filled volume V1 only (see FIG. 1) or to a larger second filled volume V2 (see FIG. 2), the second filled volume V2 corresponding to a fully inflated state of the airbag 10. The first filled volume V1 is indicated by a broken line in FIGS. 3 and 4.

[0049] In order to maintain the airbag 10 in the first filled volume V1 in a predetermined shape and to prevent the airbag 10 from further expanding into the vehicle interior, a tether element 14 is provided which is disposed in the interior 16 of the airbag 10.

[0050] The tether element 14 is tightly secured at its airbag-side end to an airbag-side permanent fixation 18 on the inside of a wall 19 of the airbag 10, in this case in the region of a baffle of the airbag 10 which forms a contact zone 20 of the airbag 10 for cushioning an occupant.

[0051] The tether element 14 is basically fastened, before a situation of restraint occurs, at its vehicle-side end on an actively detachable fixing point 22, in this case on a release unit 24 fixed to the vehicle (see FIG. 1).

[0052] In a situation of restraint in which the airbag 10 is intended to take up only the first filled volume V1, the tether element 14 remains fixed to the vehicle with its detachable fixing point 22 on the release unit 24 so that it is tensioned between the release unit 24 and its airbag-side permanent fixation 18. This state is shown in FIG. 1. The maintained connection between the release unit 24 and the actively detachable fixing point 22 allows to build up tensile stress that acts against the inner pressure of the airbag 10 and that maintains the contact zone 20 at a predetermined distance from the inflator 12. In each of FIGS. 3 and 4, said state is indicated by the broken line.

[0053] In this case, the tether element 14 remains tightly connected to the release unit 24 during the whole situation of restraint. The tether element 14 is designed so that it withstands the prevailing tensile forces. The forces acting upon the tether element 14 are derived into the vehicle via the release unit 24.

[0054] If the airbag 10 is intended to take up its second restraining state with the second filled volume V2, however, the release unit 24 is activated, for example upon reaching the first filled volume V1, so that the actively detachable fixing point 22 detaches from the release unit 24. Upon triggering of the release unit 24, the detachable fixing point 22 is provided freely in the interior 16 of the airbag 10. The tether element 14 remains connected to the airbag wall at its airbag-side fixation 18.

[0055] The release unit 24 is an electronic release unit in this case which is activated by a controller (not shown) transmitting an electronic release signal and which comprises, for example, an electronically triggerable explosive stud or an electronically controllable release mechanism (not shown in detail). In this example, the release unit 24 is shown in the vicinity of the inflator 12, but it could be provided at any suitable position fixed to the vehicle, wherein it is suitable, of course, to provide the release unit 24 as part of the airbag module 13 of the airbag 10.

[0056] Since, upon activation of the release unit 24, the contact zone 20 is no longer restrained, the airbag 10 inflates to its full volume, i.e., the second filled volume V2, and the contact zone 20 moves further into the vehicle interior than in the first filled volume V1. This state is shown in FIGS. 2, 3 and 4.

[0057] The tether element 14 initially moves along with the contact zone 20 and also into the interior 16 of the airbag 10.

[0058] In order to prevent the tether element 14 from moving completely freely in the interior 16 of the airbag 10, the tether element 14 is permanently connected to the airbag 10 (as shown here) or to the vehicle via a tether element restrainer 26.

[0059] In this example, the tether element restrainer 26 is connected, such as sewn up, at a first end at a point of action 28 permanently to the tether element 14 and, at a second end at a coupling point 30, permanently to the wall 19 of the airbag 10.

[0060] The total length of the combination of the tether element 14 and the tether element restrainer 26, based on the point of action 28, is selected so that it is larger than a distance I between the coupling point 30 and the contact zone 20 of the airbag 10 (in an imaginary fully inflated airbag 10 without a tether element restrainer 26) so that the tether element 14 and the tether element restrainer 26 are located loosely and without tensile stress in the interior 16 of the airbag 10, when the latter takes up its second filled volume V2.

[0061] However, the total length of the combination of the tether element 14 and the tether element restrainer 26, based on the point of action 28, is also selected so that it is smaller than the distance I plus a length between the point of action 28 and the permanent airbag-side fixation 18 in order to ensure that the tether element 14, specifically a vehicle-side portion 34 of the tether element 14, cannot get in touch from inside with the contact zone 20 of the airbag 10.

[0062] The exact configuration of the tether element 14 and the arrangement of the tether element restrainer 26 on the tether element 14 are possible to be varied within a broad range at the discretion of those skilled in the art.

[0063] The tether element restrainer 26 may be configured to be generally weaker than the tether element 14, as the forces acting upon the former are definitely lower than the forces which the tether element 14 must withstand in the first situation of restraint.

[0064] In the embodiment shown in FIGS. 1 and 2, the tether element 14 substantially consists of a multi-arm structure 36. The multi-arm structure 36 is formed of plural fabric cuts tightly connected to each other which form plural, such as five, arms 40. In the example shown here, all but one of the arms 40 are secured on the surface or on the edge of the contact zone 20 of the airbag 10 and form the airbag-side fixation 18. The still free arm 40 constitutes the vehicle-side portion 34 of the tether element 14.

[0065] The tether element restrainer 26 is a separate component and in this case is a tape or a cord of lower material thickness than the tether element 14.

[0066] The coupling point 28 to which the tether element restrainer 26 is secured on the vehicle-side portion 34 in this example is at a distance of several centimeters from the actively detachable fixing point 22 which is provided at the free end of the vehicle-side portion 34 here. It would also be imaginable to spatially combine the point of action 28 and the detachable fixing point 22.

[0067] Since, when the actively detachable fixing point 22 is released, the length of the tether element restrainer 26 between the coupling point 30 and the point of action 28 is additionally available, the airbag 10 can expand up to its second filled volume V2 without tensile forces acting upon the tether element 14. However, the tether element 14, and especially the vehicle-side portion 34 thereof, cannot move so far toward the contact zone 20 through the interior 16 of the airbag 10 that it could reach the contact zone 20, as the tether element 14 is prevented before from a further movement by the tether element restrainer 26.

[0068] FIGS. 3 and 4 show possible variants, but the invention is not limited to the shown examples.

[0069] In both shown variants, the tether element 14 is composed of two single components tightly connected to each other, namely the multi-arm structure 36 and a connecting element 38 which are permanently fixed to each other at a connecting point 42.

[0070] The connecting element 38 is a narrow tape or a rope or cord, for example. At one end, the connecting element 38 is connected to the free end of the vehicle-side portion 34 of the tether element 14, while an opposite end of the connecting element 38 forms the actively detachable fixing point 22 and, prior to the release of the tether element 14, is coupled to the release unit 24.

[0071] As a matter of course, it would be generally possible to make use of a different complex structure or else of a simple linear tether as tether element 14.

[0072] In FIG. 3, the tether element restrainer 26 extends in extension of the connecting element 38, the actively detachable fixing point 22 being formed at the transition from the connecting element 38 to the tether element restrainer 26.

[0073] The division between the tether element restrainer 26 and the connecting element 38 is made, for example, solely by the position of the actively detachable fixing point 22, when the connecting element 38 and the tether element restrainer 26 are formed integrally with each other and the tether element restrainer 26 substantially forms the vehicle-side end of the connecting element 38.

[0074] In this case, the detachable fixing point 22 forms at the same time the point of action 28.

[0075] Prior to the release of the tether element 14, the tether element restrainer 26 extends from the coupling point 30 to the actively detachable fixing point 22 which is fixed to the release unit 24. From there, the connecting element 38 extends to the vehicle-side portion 34 of the multi-arm structure 36 which is fixed, in turn, at its arms 40 to the airbag-side fixations 18 in the region of the contact zone 20 on the inside of the wall of the airbag 10.

[0076] When the release unit 24 is triggered, merely the connection between the release unit 24 and the actively detachable fixing point 22 is disconnected so that from then on, the actively detachable fixing point 22 hangs freely in the interior 16 of the airbag 10. All other connections are maintained.

[0077] The actively detachable fixing point 22 is thus located in the direct path between the coupling point 30 and the vehicle-side portion 34 of the tether element 14.

[0078] The embodiment shown in FIG. 4 differs from the above-described embodiment merely by the position of the point of action 28 of the tether element restrainer 26 and the actively detachable fixing point 22.

[0079] In this embodiment, the actively detachable fixing point 22 is not located in the path of the tether element restrainer 26 from the coupling point 30 to the vehicle-side portion 34 of the tether element 14. The tether element restrainer 26 is, e.g., a component provided in addition to the tether element 14 that extends in portions in parallel to the tether element 14 and here particularly in parallel to the connecting element 38. The point of action 28 is somewhat offset against the free end of the vehicle-side portion 34 of the tether element 14 toward the permanent airbag-side fixation 18 thereof.

[0080] FIG. 4 also illustrates an example in which the point of action 28 is located at the transition from the multi-arm structure 36 to the connecting element 38, i.e., at the connecting point 42.

[0081] When the tether element 14 is released, a free end 44 of the tether element 14 that includes the detachable fixing point 22 (in this case the whole connecting element 38) hangs freely in the interior 16 of the airbag 10. Therefore, the length of said free end 44 and the length of the tether element restrainer 26 should be selected to be so short that also the free end 44 cannot reach the contact zone 20. This is also applicable to the first embodiment, when the free end 44 is formed by a portion of the multi-arm structure 36 itself.