VEHICLE OCCUPANT RESTRAINT SYSTEM WITH A KNEE AIRBAG MODULE

Abstract

Vehicle occupant restraint system with a knee airbag module (12; 112) having an outer housing (20; 120) in which an airbag (16) folded together to form an airbag package (15) prior to its deployment and a gas generator (18) are accommodated, which generates filling gas for filling the airbag (16), wherein the outer housing (20; 120) has an outlet opening (36) through which the airbag (16) passes into a vehicle interior (34) and in front of an instrument panel (14; 114) upon its deployment, characterized in that the outer housing (20; 120) consists of a cover (24; 124) and a sleeve (26) made of a thin, flexible material surrounding the airbag package (15) and the gas generator (18), wherein the sleeve (26) is fixed to the cover (24; 124) and to the outer housing (20; 120) a rigid guide structure (38; 138) is provided which lies between the inflated gas bag (16) and the instrument panel (14; 114) and which has an edge (40;140) of a section of the instrument panel (14; 114) adjacent to the outlet opening (36);

Description

[0001] The invention relates to a vehicle occupant restraint system with a knee airbag module, in particular for a passenger car.

[0002] Knee airbag modules are located in the footwell of a vehicle. The airbag they contain typically deploys along the instrument panel and sits between the instrument panel and the knee / shin area of ​​the vehicle occupant. The geometry of the airbag is influenced, for example, by retaining straps located inside the airbag, which also control the movement of the airbag during deployment. In the first deployment step, the airbag, still partially folded, is designed to move in front of the instrument panel before unfolding along the instrument panel.

[0003] From DE 10 2010 007 677 A1, for example, a knee airbag module with a rigid module housing is known, which is pivotably arranged in a rigid holding frame in order to influence the exit and deployment behavior of the knee airbag.

[0004] Furthermore, US 2013 / 0 015 646 A1 shows a knee airbag module in which the airbag package of the folded knee airbag is wrapped in a cover in order to stabilize the folding of the airbag package, wherein the airbag package stabilized with the cover is inserted in a rigid housing.

[0005] The object of the invention is to improve the exit and deployment behavior of a gas bag from an outer housing of the knee gas bag module, which consists at least partially of a thin, flexible material.

[0006] For this purpose, in a vehicle occupant restraint system with a knee airbag module, the knee airbag module is provided with an outer housing containing a gas bag folded together to form a gas bag package before its deployment, and a gas generator which generates filling gas to fill the gas bag. The outer housing has an outlet opening through which the gas bag reaches the vehicle interior and in front of an instrument panel when it is deployed. A rigid guide structure is provided on the outer housing, which lies between the inflated gas bag and the instrument panel and overlaps an edge of a section of the instrument panel adjacent to the outlet opening. The guide structure arranged between the gas bag and the edge of the instrument panel guides the gas bag when it moves through the outlet opening into the vehicle interior. In this way, contact between the gas bag and the edge of the instrument panel is prevented.The guide structure is preferably located in front of the instrument panel as seen from the vehicle interior, so that the gas bag can be guided by the guide structure over the edge of the instrument panel.

[0007] The outer housing and thus the guide structure is part of the knee gas bag module and not part of the instrument panel or the vehicle-side installation space.

[0008] The direction of deployment of the gas bag is advantageously selected so that the gas bag package emerges from the outer housing into the vehicle interior while still partially folded and then the gas bag unfolds along the instrument panel towards the vehicle occupant.

[0009] The guide structure preferably adjoins the edge of the instrument panel essentially without a gap in order to ensure that the gas bag is guided safely over the edge of the instrument panel.

[0010] It is possible to position the guide structure relative to the instrument panel in such a way that, when the airbag deploys, the guide structure transmits a force directed away from the vehicle interior to the edge of the instrument panel. In this case, the guide structure can press against the edge of the instrument panel when the airbag deploys, thus keeping it out of the airbag's deployment path.

[0011] The outer housing preferably has a cover in which a weakened zone is provided, which defines a flap that closes the outlet opening before the airbag is deployed. During the deployment of the airbag, the filling gas flowing into the airbag builds up pressure in the outer housing, causing the weakened zone to yield. The part of the cover that forms the flap then pivots into the vehicle interior, thus exposing the outlet opening. The flap normally remains connected to the rest of the cover at a hinge zone, whereby this hinge zone is usually provided on a side of the outer housing facing away from the guide structure.

[0012] The guide structure can be arranged adjacent to the weakened zone in the direction of the vehicle occupant, so that the guide structure is in the immediate vicinity of the edge of the outlet opening.

[0013] However, the guide structure should always be located on a section of the outer casing that remains in its original position when the outlet opening is opened and released, and not on the flap that swings open when the gas bag is deployed. The guide structure should preferably change its position only slightly during the release of the outlet opening and during the deployment of the gas bag.

[0014] According to the invention, the outer housing essentially consists of the cover and a sheath made of a thin, flexible material that surrounds the airbag module and the gas generator. According to the invention, the sheath is fixed to the cover so that the cover and sheath completely seal off the knee airbag module from the outside. The sheath also serves to hold the airbag module together.

[0015] The cover may have raised edges that define a space for the gas bag package and that extend to approximately one-third or one-half of the height of the gas bag package.

[0016] As is known, the knee gas bag module can be fixed to the vehicle body by attaching the gas generator.

[0017] In a first preferred embodiment, the guide structure is formed by a rigid projection on the outer housing, which covers the edge of the instrument panel on the vehicle interior side.

[0018] This projection can extend on the outer casing, for example, as an extension of the flap that closes the outlet opening before the gas bag deploys. The guide structure is then advantageously arranged on the side of the cover facing the occupant.

[0019] According to a second preferred embodiment, the guide structure is formed by a rigid section of the outer housing running along the gas bag package and at an angle to the plane of the outlet opening.

[0020] In this embodiment, in particular the edge of the instrument panel runs at an angle and parallel to the guide structure, so that the guide structure also covers the edge of the instrument panel when viewed from the vehicle interior and ensures that the gas bag slides along the guide structure when it exits into the vehicle interior without coming into contact with the edge of the instrument panel.

[0021] The guide structure preferably lies on the edge of the instrument panel and, in this embodiment, can also transmit a force directed away from the vehicle interior to the edge of the instrument panel when the gas bag unfolds.

[0022] Generally, the guide structure can run transversely to the vehicle's longitudinal axis when the knee airbag module is installed. It is preferably located on the edge of the outer housing closest to the vehicle seat and adjacent to the footwell. Thus, it guides the airbag across its entire width, transversely to the vehicle's longitudinal axis, over the edge of the instrument panel.

[0023] The invention is described in more detail below using two exemplary embodiments with reference to the accompanying drawings. In the drawings: - Fig. 1 is a schematic sectional view of a vehicle occupant restraint system according to the invention in accordance with a first embodiment; and - Fig. 2 a schematic sectional view of a vehicle occupant restraint system according to the invention according to a second embodiment.

[0024] Fig. 1 shows a first embodiment of a vehicle occupant restraint system 10 according to the invention with a knee airbag module 12. The knee airbag module 12 is arranged in an opening of an instrument panel 14 or, if appropriate, adjacent to a lower end of the instrument panel 14.

[0025] The knee airbag module 12 has a gas bag 16 folded into a gas bag package 15, which is accommodated together with a gas generator 18 in an outer housing 20. In this example, the knee airbag module 12 is firmly connected to the vehicle body via fastening elements 22 of the gas generator 18 (not shown).

[0026] The knee airbag module 12 is positioned such that the airbag package 15 and the gas generator 18 are located behind the instrument panel 14, so that a front side of the outer housing 20 fits into the course of the instrument panel 14.

[0027] In this example, the front of the outer housing 20 is formed by a cover 24.

[0028] The remainder of the outer housing 20 consists of a thin, flexible cover 26, for example, a film or a coated fabric, which is tightly pulled over the gas generator 18 and the folded airbag package 15 and which is fixed to raised, circumferential edges 28 of the cover, for example by gluing or welding. The raised edges 28 of the cover 24 form a rigid frame that extends approximately over one-third to over half the height of the airbag package 15 in the direction away from the vehicle interior 34.

[0029] The cover 24 and the shell 26 completely surround the gas bag package 15 and the gas generator 18 and seal them off from the environment.

[0030] The outer casing 20 could of course also be designed differently.

[0031] One or more weakened zones 30 are formed in the cover 24, for example in the form of areas of thinner material thickness, which act as predetermined breaking points. These weakened zones 30 define a flap 32. At the beginning of the deployment of the gas bag 16, the weakened zones 30 open due to the gas pressure generated by the gas generator 18, and the flap 32 pivots outward, releasing an outlet opening 36 through which the gas bag 16 exits into the vehicle interior 34. Fig. 1 and Fig. 2, the flap 32 is indicated in the open state by dashed lines. In Fig. 1, the gas bag 16 is also shown schematically in the unfolded state with dashed lines.

[0032] A rigid guide structure 38 is provided on the outer housing 20, which overlaps an edge 40 of the instrument panel 14, which is arranged adjacent to the outlet opening 36. When the gas bag 16 is deployed, the guide structure 38 lies between the gas bag 16 and the edge 40 of the instrument panel 14. In this embodiment, the guide structure 38 is formed as an extension of the cover 24 in the direction of the instrument panel 14. Here, it is designed as a molded-on thickening on the cover 24, which merges into the raised edge 28 of the cover 24.

[0033] The guide structure 38 essentially adjoins the weakened zone 30, i.e., directly at the edge of the outlet opening 36. The guide structure 38 is arranged on the part of the cover 24 that does not belong to the flap 32, which pivots open when the outlet opening 36 is opened.

[0034] The guide structure 38 extends into the image plane with a substantially constant cross-section, for example over the entire width of the outer housing 20 transversely to the vehicle longitudinal axis, but at least over the entire width of the outlet opening 36.

[0035] The edge 40 of the instrument panel 14 and the guide structure 38 overlap each other, so that the edge of the edge 40 of the instrument panel 14 lies completely on the rear side of the guide structure 38 facing away from the vehicle interior 34.

[0036] The aim is for the guide structure 38 and the edge 40 of the instrument panel 14 to adjoin one another with as little gap as possible. In the example shown, the edge 40 of the instrument panel 14 and the guide structure 38 are already touching in the state before the gas bag 16 is deployed.

[0037] When the knee airbag module 12 is activated, the airbag package 15 exits the outer housing 20 in a still partially folded state through the outlet opening 36 into the vehicle interior. The airbag 16 then unfolds along the instrument panel 14 toward the knee / shin area of ​​the vehicle occupant, as shown in Fig. 1 is indicated by dashed lines.

[0038] The guide structure 38 lies between the unfolding gas bag 16 passing through the outlet opening 36 and the edge 40 of the instrument panel 14, so that the gas bag 16 is guided past the edge 40 of the instrument panel 14 by the guide structure 38 without coming into contact with the edge 40 of the instrument panel 14.

[0039] The guide structure 38 is designed to be so rigid that it essentially does not deform. However, the guide structure 38 can exert a force F on the edge 40 of the instrument panel 14 away from the interior, which moves the edge 40 of the instrument panel 14 a small distance, for example, a few millimeters, away from the vehicle interior 34, thus securely keeping the edge 40 of the instrument panel 14 out of the deployment path of the gas bag 16.

[0040] The side of the guide structure 38 facing away from the vehicle interior is concavely rounded here, and the edge 40 of the instrument panel 14 is adapted to the curvature of the guide structure 38 so that the edge 40 can lie flat against the side of the guide structure 38 facing away from the vehicle interior.

[0041] Fig. 2 shows a second embodiment of a vehicle occupant restraint system 100.

[0042] Components already known from the first embodiment, identical or only slightly modified, retain the reference symbols already introduced for reasons of clarity.

[0043] In contrast to the first embodiment, the guide structure 138 here is formed by a section of the outer housing 120 on the side of the outer housing 120 facing the vehicle occupant, more precisely by a section of the raised edge 128 of the cover 124. The guide structure 138 extends at an acute angle to the plane of the outlet opening 36, away from the outlet opening 36 in the direction away from the vehicle interior 34. This provides an inclined plane for guiding the gas bag package 15 as it passes through the outlet opening 36, which guides the gas bag 16 around the edge 140 of the instrument panel 114.

[0044] The edge 140 of the instrument panel 114 is configured to follow the guide structure 138 and run parallel to it essentially without a gap. Here, too, the guide structure 138 overlaps the edge 140 of the section of the instrument panel 114 adjacent to the outlet opening 36. In the direction away from the vehicle interior 34, the guide structure 138 projects beyond the edge 140 of the instrument panel 114. The guide structure 138 is also longer than the remaining raised edge 128 of the cover 124.

[0045] Also in this embodiment, the guide structure 138 is substantially rigid and is arranged on the portion of the outer housing 20 which does not belong to the flap 32 and which remains substantially in its original position when the weakened zone 30 is opened and the outlet opening 36 is released.

[0046] When the gas bag package 15 exits the outer housing 20 through the outlet opening 36, it exerts a force F on the guide structure 138, which is transferred to the edge 140 of the instrument panel 114 and pushes it away from the vehicle interior 34. In this way, the edge 140 of the instrument panel 114 is securely held out of the deployment path of the gas bag 16.

[0047] The individual features of the two embodiments can, of course, be combined with one another or, if necessary, exchanged for one another at the discretion of the person skilled in the art.

Claims

Vehicle occupant restraint system with a knee airbag module (12; 112) having an outer housing (20; 120) in which an airbag (16) folded together to form an airbag package (15) prior to its deployment and a gas generator (18) are accommodated, which generates filling gas for filling the airbag (16), wherein the outer housing (20; 120) has an outlet opening (36) through which the airbag (16) passes into a vehicle interior (34) and in front of an instrument panel (14; 114) upon its deployment, characterized in that the outer housing (20; 120) consists of a cover (24; 124) and a sleeve (26) made of a thin, flexible material surrounding the airbag package (15) and the gas generator (18), wherein the sleeve (26) is fixed to the cover (24; 124) and to the outer housing (20; 120) a rigid guide structure (38; 138) is provided which lies between the inflated gas bag (16) and the instrument panel (14; 114) and which has an edge (40;140) of a section of the instrument panel (14; 114) adjacent to the outlet opening (36); Vehicle occupant restraint system according to claim 1, characterized in that the guide structure (38; 138) adjoins the edge (40; 140) of the instrument panel (14; 114) essentially without a gap. Vehicle occupant restraint system according to one of the preceding claims, characterized in that the guide structure (38; 138) is arranged relative to the instrument panel (14; 114) in such a way that, when the gas bag (16) is deployed, it introduces a force (F) directed away from the vehicle interior (34) into the edge (40; 140) of the instrument panel (14; 114). Vehicle occupant restraint system according to one of the preceding claims, characterized in that the outer housing (20; 120) has the cover (24; 124) in which a weakened zone (30) is provided, wherein the cover (24; 124) defines a flap (32) closing the outlet opening (36) before the deployment of the gas bag (16). Vehicle occupant restraint system according to claim 4, characterized in that the guide structure (38; 138) is arranged adjacent to the weakened zone (30) in the direction of the vehicle occupant. Vehicle occupant restraint system according to one of the preceding claims, characterized in that the guide structure (38) is formed by a rigid projection on the outer housing (20) which covers the edge (40) of the instrument panel (14) on the vehicle interior side. Vehicle occupant restraint system according to one of claims 1 to 5, characterized in that the guide structure (138) is formed by a rigid section of the outer housing (120) running along the gas bag package (15) and at an angle to the plane of the outlet opening (36). Vehicle occupant restraint system according to claim 7, characterized in that the edge (140) of the instrument panel (114) is angled and runs parallel to the guide structure (138). Vehicle occupant restraint system according to one of the preceding claims, characterized in that the guide structure (38; 138) runs transversely to the vehicle longitudinal axis in the installed state of the knee gas bag module (12; 112) and is provided on the edge of the outer housing (20; 120) close to a vehicle seat and adjacent to a footwell.

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