Optimized knee bag folding

Abstract

Method for assembling a knee gas bag (10) with a fastening section (14) having an inlet section (12), an inflation section (16) and an intermediate discharge section (18) having a width B having parallel opposite edges, the method comprising the following steps: - The knee gas bag (10) is spread out flat; - The ejection section (18) of the knee gas bag (10) is folded at least once; - The inflation section (16) of the knee airbag (10) is rolled up from a section (20) opposite the fastening section (14) in a first rolling direction (X) towards the fastening section (14); - The inflation section (16) of the knee airbag (10) is rolled up from at least one side edge (22, 24) in a second rolling direction (Y1, Y2) which does not coincide with the first rolling direction (X), whereby the rolling up of the at least one side section (22, 24) of the knee airbag (10) takes place up to the width of the inflation section (12); - The inflation section (16) of the knee airbag (10) is rolled up in the first rolling direction (X) to the folded discharge section (18).

Description

[0001] The invention relates to a method for folding a knee airbag for a motor vehicle, and to a knee airbag that is folded according to this method.

[0002] Knee airbags for vehicles are known from the prior art; these are installed in the vehicle in the area of ​​the lower extremities of the vehicle occupant and inflate when activated, protecting the vehicle occupant from an impact on the vehicle interior.

[0003] The knee airbags are typically located in a housing behind the vehicle's interior trim. When activated, the knee airbag inflates and is forced out of the housing. The interior trim has a predetermined breaking point or opening in the area of ​​the knee airbag, through which the airbag is pushed into the vehicle's interior and inflates. For the knee airbag to inflate properly, it is essential that it only deploys after it is outside the housing. Experience has shown that the deployment behavior of the knee airbag is significantly influenced by how it is folded.

[0004] German patent DE 694 01 767 T2, for example, shows a passenger airbag in which, among other things, the center of the airbag is folded towards the opening, creating an upper and a lower fold. These folds are then rolled up together before opposite sides of the rolled-up airbag fabric are folded between the upper and lower folds. These folds cause the passenger airbag to unfold relatively slowly in a downward trajectory. However, such a slow unfolding is neither desirable nor advantageous for a knee airbag.

[0005] US Patent 5,022,675 A also depicts a passenger airbag. In this design, opposite sides of the airbag cushion are folded multiple times between the outer sections of the airbag before a crease is formed at the end of the fold. This crease is initially filled when the passenger airbag is deployed, briefly acting as a restraint for the remaining folded and rolled sections. This, along with the folded sides, also results in the slow deployment of the airbag, which is neither desirable nor advantageous in a knee airbag.

[0006] The object of the invention is to create a method for folding a knee airbag, whereby the knee airbag has an optimized unfolding behavior.

[0007] To solve this problem, the invention provides a method for folding a knee airbag by means of the following steps: The knee airbag is laid flat. The knee airbag is then folded at least once in a discharge section located between the attachment section and the inflation section. Starting from a section opposite the attachment section, the inflation section of the knee airbag is partially rolled up in a first direction towards the attachment section. The inflation section of the knee airbag is then rolled up from at least one side edge in a second direction that does not coincide with the first direction. Finally, the inflation section of the knee airbag is rolled up in the first direction until it reaches the folded discharge section.

[0008] When the knee airbag is activated, the gas flows through the inlet section first into the folded discharge section of the knee airbag, before flowing into the inflation section and unfolding it. The incoming gas inflates the folded discharge section first. As the gas expands, the still-folded inflation section is forced out of the housing. The gas then flows into the inflation section and fills it. This process ensures that the inflation section of the knee airbag exits the housing before it inflates. This prevents the partially inflated knee airbag from becoming jammed in the housing or from inflating in an undesired position.

[0009] In a first embodiment, the first rolling direction, in which the section opposite the discharge section is rolled up, lies at right angles to the folded discharge section. The inflation section is thus rolled up around an axis parallel to the folded discharge section. The inflation section of the knee airbag can therefore be rolled up very close to the discharge section across its entire width. The folded knee airbag thus achieves the narrowest possible shape, enabling installation with a shallow installation depth.

[0010] In a second embodiment, the second rolling direction, in which at least one side section of the knee airbag is rolled up, is perpendicular to the first rolling direction of the inflation section. This gives the partially folded knee airbag a shape with side edges running parallel to the first rolling direction. When the knee airbag is rolled up further in the first rolling direction, these edges lie on top of each other, thus defining the width of the rolled-up knee airbag package, which corresponds, for example, to the installation width of the knee airbag in a housing. Together with a first rolling direction running perpendicular to the folded discharge section, this results, after the inflation section is rolled up, in an elongated package with its longitudinal axis parallel to the folded discharge section. This package can be rolled up close to the discharge section across its entire width.This gives the folded knee gasbag a very compact shape, which allows for space-saving installation of the knee gasbag.

[0011] The rolling up of at least one side section of the knee airbag in the second rolling direction preferably extends to the width of the blowing section. This gives the folded knee airbag the most compact shape possible, allowing it to be installed in a housing in a space-saving manner.

[0012] To solve the above-mentioned problem, a gasbag module is also provided according to the invention, which has a knee gasbag that is folded according to one of the described methods and has a gas generator in the injection section.

[0013] Preferably, the gas generator is a tubular gas generator, and its longitudinal axis lies parallel to the folded discharge section of the knee gas bag and / or perpendicular to the first rolling direction. This gives the gas bag module a space-saving shape.

[0014] In another embodiment of the gasbag module, a packing strip is provided which is placed around the knee gasbag and secured after it has been folded. This holds the gasbag module together with the folded knee gasbag and allows it to be easily transported and / or installed in its folded state.

[0015] Preferably, the packing strip is fixed to the mounting bolts of the gas generator. This eliminates the need for any additional fastening devices for the packing strip on the gas bag module.

[0016] In another embodiment, the gasbag module is housed in a casing, and the width of the folded discharge section is greater than the installation depth of the gasbag module in the casing. This ensures that the inflation section of the knee gasbag fully extends from the casing before it is inflated when activated.

[0017] Further features and advantages of the invention will become apparent from the following description in conjunction with the accompanying drawings. These show: - Fig. 1 a kneeling bag, in a flat, spread-out form, - Fig. 2 the knee bag out Fig. 1 after a first folding step, - Fig. 3. Remove the knee airbag Fig. 2 in a cross-section, - Fig. 4. Remove the knee bag Fig. 2 after a second folding step, - Fig. 5 the knee bag out Fig. 4 after a third folding step, - Fig. 6. Remove the knee bag Fig. 5 after a fourth folding step, - Fig. 7 a folded knee gasbag according to one design variant, - Fig. 8 a gasbag module with a knee gasbag in a fixed state, - Fig. 9 the gasbag module from Fig. 8 in a cross-section, - Fig. 10 a gasbag module that is installed in a housing, - Fig. 11 the gasbag module from Fig. 10, with the ejection section extended.

[0018] Fig. Figure 1 shows an extended knee airbag 10, with an inflation section 16, a fastening section 14, and a discharge section 18 located between the fastening section 14 and the inflation section 16, which has a width B. The fastening section 14 has fastening openings 28 and an inflation section 12 at one end. The inflation section 16 has a section 20 opposite the fastening section and two side edges 22 and 24.

[0019] In the event of activation, the gas flows through the inlet section 12 and first fills the discharge section 18 before flowing into and filling the inflation area 16 of the knee airbag. In the embodiments according to the invention, the discharge section 18 has parallel, opposing edges.

[0020] The ejection section 18 is folded once accordion-like, essentially parallel to the fastening section 14 ( Fig. 2 and Fig. 3) For this purpose, the discharge section 18 is folded in the area of ​​the transition from the discharge section 18 to the mounting section 14 and in the area of ​​the transition from the discharge section 18 to the inflation section 16, and folded in the opposite direction approximately in the middle of the discharge section 18. In the illustrated embodiment, the discharge section 18 is folded once in an accordion-like fashion, but it is also conceivable that the discharge section is folded several times. The fold runs essentially parallel to the mounting section 14 or to the inflation section 12. However, the discharge section 18 can also be folded in any other way.

[0021] The inflation section 16 is rolled up by means of the following steps: The inflation section 16 of the knee airbag 10 is partially rolled up in a first rolling direction X towards the fastening section 14 by a section 20 which is opposite the fastening section 14 ( Fig. 4).

[0022] Subsequently, the inflation section 16 of the knee airbag 10 is rolled up in a second rolling direction Y1 starting from a first side edge 22 ( Fig. 5).

[0023] Subsequently, the inflatable section 16 is partially rolled up from a second side edge 24 in a rolling direction Y2 ( Fig. 6).

[0024] In the illustrated embodiment, the first rolling direction X is perpendicular to the folded ejection section 18, and the second rolling direction Y1 or Y2 is perpendicular to the first rolling direction X or parallel to the folded ejection section 18, respectively. However, the rolling directions X, Y1, and Y2 can also be in other directions, depending, for example, on the shape of the knee airbag, the available space during installation, or the desired shape of the folded knee airbag. In particular, the rolling directions Y1 and Y2 do not have to be parallel to each other. Furthermore, it is conceivable that the knee airbag is rolled up in the second rolling direction Y1 only from one side edge, for example, if the knee airbag has a highly asymmetrical shape.

[0025] Fig. Figure 7 shows a knee gas bag 10, which was folded according to the described method, with an inflation section 16, which was rolled up according to one of the described methods, a folded ejection section 18, a fastening section 14, and a spread-out packing strip 32 arranged on the knee gas bag. The fastening section 14 is fixed by two bolts 30, which extend through the fastening openings 28.

[0026] Fig. 8 and Fig. Figure 9 shows a gasbag module with a knee gasbag 10, which is folded according to one of the described methods, with a gas generator 26 and a packing strip 32, which is placed around the gasbag module and fixed. In the embodiment shown, the packing strip 32 is fixed to the mounting bolt 30 of the gas generator. However, other variants for fixing the packing strip 32 are also conceivable.

[0027] Fig. 10 shows a gasbag module made of Fig. 8 and Fig. 9 in cross-section, which is installed in a housing. The gas bag module is attached to the housing by the mounting bolts 30 of the gas generator. The gas bag module is inserted into the housing with an installation depth D.

[0028] Fig. 11 shows the gasbag module Fig. 10 in a partially deployed state. The gas generator has filled the discharge section 18 of the knee airbag 10 with gas; the inflation section 16 is not yet filled. The discharge section 18 of the knee airbag 10 has a width B that is greater than the installation depth D of the knee airbag 10 in the housing 34. This ensures that the inflation section 16 of the knee airbag 10 is completely pushed out of the housing 34 when the discharge section 18 is deployed and can fully inflate.

Claims

[1] Method for assembling a knee gas bag (10) with a fastening section (14) having an inflation section (12), an inflation section (16) and an intermediate discharge section (18) having a width B having parallel opposite edges, the method comprising the following steps: - The knee gas bag (10) is spread out flat; - The ejection section (18) of the knee gas bag (10) is folded at least once; - The inflation section (16) of the knee airbag (10) is rolled up from a section (20) opposite the fastening section (14) in a first rolling direction (X) towards the fastening section (14); - The inflation section (16) of the knee airbag (10) is rolled up from at least one side edge (22, 24) in a second rolling direction (Y1, Y2) which does not coincide with the first rolling direction (X), whereby the rolling up of the at least one side section (22, 24) of the knee airbag (10) takes place up to the width of the inflation section (12); - The inflation section (16) of the knee airbag (10) is rolled up in the first rolling direction (X) to the folded discharge section (18). [2] Method according to claim 1, characterized by , that the first rolling direction (X) is perpendicular to at least one fold in the ejection section (18). [3] Method according to claim 1 or 2, characterized by , that the second rolling direction (Y1, Y2) is perpendicular to the first rolling direction (X). [4] Gasbag module with a knee gasbag (10), characterized by, that the knee gas bag (10) is folded according to one of the preceding claims and has a gas generator (26) in the injection section (12). [5] Gasbag module according to claim 4, characterized by , that the gas generator (26) is a tubular gas generator and the longitudinal axis is essentially parallel to the at least one fold and / or perpendicular to the first rolling direction (X). [6] Gasbag module according to claim 4 or 5, characterized by , that a packing strip (32) is provided which, after folding, is placed around the knee gas bag (10) and secured. [7] Gasbag module according to claim 6, characterized by , that the packing strip (32) is fixed to the fastening bolts (30) of the gas generator (26). [8] Gasbag module according to any one of claims 4 to 7, characterized by , that the gasbag module has a housing (34) and the width of the discharge section (B) is greater than the installation depth (D) of the gasbag module.

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