Airbag with active ventilation device

Abstract

An airbag with an active ventilation device is described. The airbag has a first skin surrounding a first gas space. The first skin's first layer (10) has an inner surface (10b) facing the first gas space and an outer surface (10a) facing away from the first gas space. The active ventilation device includes a penetration (14) in the first layer (10) and a cover element (52) disposed on the outer surface (10a) of the first layer (10), the cover element (52) at least partially covering the penetration (14) and permanently connected to the first layer (10) by a cover element connection (62), which is not closed, resulting in an open area between the first layer (10) and the cover element (52). The active venting device further comprises an expansion assembly having a second skin (42) enclosing a second gas space (47) and a gas generator. The second skin is disposed on the inner surface (10b) of the first layer (10) and at least partially overlaps the cover element (52). A tear seam (66) is provided as a further element of the active venting assembly. The tear seam has a portion that extends through the cover element (52), the first layer (10), and the second skin (42), thus preventing or limiting leakage of gas through the opening area in the first state of the venting device (FIG. 13).

Description

[Technical Field]

[0001] The present invention relates to an airbag comprising an active ventilation device according to claim 1 and to an airbag unit comprising such an airbag and a primary inflator according to claim 12. [Background technology]

[0002] Each airbag used to protect a vehicle occupant in the event of an accident has an outer skin (hereinafter also referred to as the first skin) surrounding a first gas space, the first skin having at least one first layer with an inner surface facing the first gas space and an outer surface facing away from the first gas space.

[0003] It is known to equip such airbags with an active venting device having a first, constricted or closed state and a second, open state, wherein the first layer has perforations through which gas can escape in at least the second state.

[0004] Such an airbag with a ventilation device is known from DE 10 2012 016 460 B4. Here, a sleeve is provided that extends around the penetration and is connected to a first skin, from which a tension element extends. The end of the tension element facing away from the sleeve is connected to a second skin ("microbag") via a tear seam, which can be filled with a gas generator to tear the tear seam. The first skin and the associated gas generator form an expanded assembly. When the first skin is fully inflated but the second skin is not, the tension element is under tensile stress and holds the sleeve in tension within the first gas space, resulting in the ventilation device being in its first, constricted state. When the gas generator is ignited, the second skin expands and the tear seam ruptures. This releases the second end of the tear seam and causes the sleeve to be forced outward by gas pressure in the first gas space, causing the venting device to assume its open second condition.

[0005] A drawback of this prior art technique is that there is a certain time delay between the activation of the gas generator of the expansion element and the full attainment of the second state, since the sleeve must first be rotated outwards. Summary of the Invention

[0006] Based on this, the present invention aims in particular to provide an airbag with an alternatively designed venting device, which is able to achieve a very short time delay between ignition of the gas generator of the expansion element and full achievement of the second state.

[0007] This problem is solved by an airbag having the features of claim 1. An airbag unit comprising such an airbag and a main inflator is described in claim 12.

[0008] The airbag according to the present invention has a cover element arranged on the outer surface of the first layer and firmly connected to the first layer, which at least partially, preferably completely, covers the penetration. The connection between the first layer and the cover element is made by an open cover element connection, which results in an open area between the first layer and the cover element. For this purpose, the cover element connection can be designed in a U-shape.

[0009] Similar to the airbag of DE 10 2012 016 460 B4, an expansion assembly is provided, including a second skin surrounding the second gas space and a gas generator. However, this expansion assembly is not used to hold and release the pulling element; rather, it directly influences the state of the penetration and the state of the cover element. For this purpose, the second skin is arranged inside the first layer and at least partially overlaps the cover element, particularly in the opening area. The airbag according to the present invention also includes a tear seam. This tear seam has a portion extending through the cover element, the first layer, and the second skin. The tear seam at least partially, preferably completely, blocks gas leakage through the opening area and maintains the ventilation device in the first state, which can be completely sealed.

[0010] When the gas generator is ignited, the expansion of the first skin causes the tear seam to rupture and the open area to be released, allowing gas from the first gas space to flow through the penetration into the area between the first layer and the cover element, from where it can escape through the now open open area.

[0011] The ventilation device according to the invention has the following advantages in particular: Due to the arrangement of the second skin and the tear seam, the time delay between the activation of the gas generator and the reaching of the second state is very short. This also means that the ventilation device has practically no undefined intermediate states between the first and second states, resulting in a very reproducible behavior. Finally, both the completely closed first state and the second state with a large opening cross-section, i.e., strong ventilation, can be achieved.

[0012] Preferably, the penetration has at least one slit-shaped portion or is designed as a slit overall. This measure allows the pressure acting between the first layer and the cover element in the first state to be kept low, allowing the cover element to be released. A slit is a structure in which opposing edges are in contact, or at least nearly in contact, i.e., there is essentially no "missing" material between the opposing edges. Only when the slit is open can significant gas passage occur, which is where a slit is significantly distinguished from an elongated hole.

[0013] In order to increase the free cross-section in the second state, the cover element may be folded in the first state and may preferably be at least partially at least three-layered, and in the second state the cover element expands so that the free cross-section between the cover element and the first layer increases at least in the opening region.

[0014] In a first preferred embodiment, the first (outer) skin of the airbag further comprises a second layer, and the ventilation device is located in the region of the edge of the first layer, i.e., the region where the two layers meet. Furthermore, the penetration extends to the edge of the first layer, which is permanently connected to the second layer along its edge by an edge connection, and at least the region of the ventilation device where the penetration terminates at the edge, preferably the entire opening region, is free of permanent connections. A tear seam crosses the penetration. This type of airbag is easy to manufacture and provides a large ventilation cross-section in the second state, especially if the penetration is slit-shaped.

[0015] In the above-described embodiments, it is generally advantageous for the gas generator of the expansion assembly to be located outside the first gas space. Therefore, it is preferred that a portion of the second skin protrudes beyond the edge of the first skin, and this portion is located outside the first gas space. For ease of assembly, the second layer may have a bulge located outside the first gas space, so that the bulge at least partially overlaps with the portion of the second skin.

[0016] Also, for ease of assembly, the second skin may be connected to the second layer by an assembly connection that connects only the second skin to the second layer of the first skin.

[0017] In a second preferred embodiment, the ventilation device is arranged in a region of the first layer that is spaced apart from the edge, and the second layer is not included in the ventilation device, in which case it is particularly advantageous to design the openings in the first layer in a T-, V- or U-shape.

[0018] Preferably, only the tear seam extends through the second gas space so as not to impede expansion of the second skin.

[0019] Preferably, at least one layer of the second skin is gas permeable to allow gas to escape from the second skin after expansion of the second skin and resulting at least partial tearing of the tear seam, thereby preventing the expanded second skin from impeding ventilation in the second state of the venting device. Gas permeability can be achieved, for example, by microperforations. [Brief explanation of the drawings]

[0020] The invention will now be described in more detail with reference to preferred embodiments in the light of the figures, which show: [Figure 1] FIG. 1 is a schematic diagram of all components (excluding seams) of a first embodiment of an airbag unit. [Figure 2] FIG. 2 shows detail D1 of FIG. 1 on an enlarged scale, but from a rearward perspective relative to FIG. [Figure 3] FIG. 3 shows detail D2 of FIG. [Figure 4] FIG. 4 shows detail D3 of FIG. 1, ie the second skin and the gas generator. [Figure 4a] FIG. 4a is a cross-sectional view along plane AA of FIG. [Figure 4b]FIG. 4b shows an expanded assembly consisting of the second skin and gas generator of FIG. [Figure 5] FIG. 5 shows detail D4 of FIG. 1, namely the cutting of the cover element. [Figure 6] FIG. 6 shows the cover element folded from the cut of FIG. [Figure 6a] 6a is a side view of the cover element of FIG. 6 from direction R in FIG. [Figure 7] FIG. 7 is a view of the second layer of the first skin shown in FIG. 2 and the portion of the expansion assembly shown in FIG. 4b attached to the first skin by an assembly seam. [Figure 8] 8 is a view of the first layer of the first skin shown in FIG. 3 and a portion of the folded cover element shown in FIG. 6 attached to the first skin by a cover element seam. [Figure 9] FIG. 9 shows the article shown in FIG. 7 and the article shown in FIG. 8 after the first skin has been folded along its fold line. [Figure 10] FIG. 10 shows the article shown in FIG. 9 after the edge seam portions have been attached. [Figure 11] FIG. 11 shows the article shown in FIG. 10 after the tear seam has been attached. [Figure 12] FIG. 12 shows the article shown in FIG. 11, with hidden elements not shown. [Figure 13] FIG. 13 shows a highly schematic representation of the layer structure of the venting device. [Figure 14] FIG. 14 shows the ventilation device in a configuration corresponding to FIG. 12 after activation of the gas generator of the expansion element. [Figure 15] FIG. 15 shows the article shown in FIG. 13 in a state after activation of the gas generator (corresponding to the state shown in FIG. 14). [Figure 16] FIG. 16 shows a schematic diagram of all components (excluding seams) of a second embodiment of an airbag unit. [Figure 17] FIG. 17 is a diagram showing detail D5 of FIG. [Figure 18] 18 shows the first layer of the first skin shown in FIG. 17 and a portion of the folded cover element shown in FIG. 6 fastened to the outer surface of the first skin by a cover element seam. [Figure 19] FIG. 19 illustrates the article shown in FIG. 18 and an expansion unit disposed on the inner surface of the first layer of the first skin. [Figure 20] FIG. 20 shows the article shown in FIG. 19 after a tear seam has been applied. [Figure 21] FIG. 21 shows the article shown in FIG. 20, with hidden elements not shown. [Figure 22] FIG. 22 shows an alternative design of the tear seam in the representation according to FIG. [Figure 23] FIG. 23 shows in a schematic representation all the components (except the seams) of the second embodiment variant of the airbag unit according to FIG. [Figure 24] FIG. 24 is a diagram showing detail D6 of FIG. [Figure 25] FIG. 25 shows the detail shown in FIG. 24 and the cover element shown in FIG. 23 (corresponding to FIG. 8) which is sewn to the first layer in the folded state and covers the penetration. [Figure 26] FIG. 26 is the detail shown in FIG. 25 with the expansion assembly disposed on the inner surface of the first layer. [Figure 27] FIG. 27 shows the article shown in FIG. 26 after assembly seams and tear seams have been applied (corresponding to FIG. 20). [Figure 28] FIG. 28 is a view of the arrangement shown in FIG. 27, but without the expansion assembly. [Figure 29] FIG. 29 shows the arrangement shown in FIG. 28 with an alternative tear seam design. DETAILED DESCRIPTION OF THE INVENTION

[0021] The invention will now be explained by way of the example of an airbag unit, which comprises an airbag and a primary inflator. In the described example, the airbag is a side airbag (a so-called 2D airbag) whose outer skin (hereinafter referred to as the first skin) has a simple basic structure with only two layers. However, this should be understood as an example only. The invention can in principle be applied to any airbag or airbag unit. The only important feature is that the airbag has an actively controllable ventilation device.

[0022] To better understand the structure of the airbag according to the invention, and in particular its venting device, the manufacture of the airbag from its components will first be described. Only the components absolutely necessary for this embodiment of the invention are shown and described, but it will be appreciated that an airbag according to the invention may have further components (such as an inner tether or an outer tether). However, for simplicity of explanation, such further (optional) components are not shown or described.

[0023] 1 shows all components of a side airbag unit according to the present invention, namely the airbag components (excluding connections, especially seams) and the primary inflator 30. Like any airbag, the airbag has a first skin (also called the outer skin) that surrounds a first gas space. The primary inflator 30 is used to fill this first gas space.

[0024] In the illustrated embodiment, the first skin (outer skin) has two layers 10, 20, which are made from a joint cut 5' by folding along a fold line F (so-called butterfly design). However, this is not essential to the invention; the two layers can also be made from separate cuts.

[0025] In the illustrated exemplary embodiment of the first embodiment, the venting device is located in the edge region where the two layers are connected to one another. While it is possible to locate the venting device away from such edge region, this is generally not preferred.

[0026] With this in mind, the components shown in FIG. 1 are described below. The first skin joint section 5' has a first portion for the first layer 10 and a second portion for the second layer 20. These two portions are folded onto each other along the fold line F to form the first skin, as is known in the art. As mentioned above, separate cuts for the two layers can also be provided. The first layer 10 (obviously) has an outer surface 10a and an inner surface 10b. In this regard, inner surface means that, when the airbag is fully assembled, this inner surface 10b faces, at least in part, the first gas space enclosed by the outer skin. Of course, the same applies to the second layer 20, which has an inner surface 20b and an outer surface 20a that at least in part face the gas space. In the state of the first skin shown in FIG. 1, the outer surfaces 10a, 20a of the two layers 10, 20 are visible.

[0027] In the edge region (in the embodiment shown, in the region of the edge opposite the fold line F), the first layer 10 has a slit-shaped penetration 14 extending to the edge (detail D2 in FIG. 3). A first end 14a (inner end) of the slit-shaped penetration 14 opposite the edge is widened and is approximately circular in shape. Opposite the region of the first layer 10 described above, the second layer 20 has a bulge 22 in the edge region (detail D1 in FIG. 2). The slit 14 and the bulge 22 are components of the active ventilation device according to the invention.

[0028] Figure 1 also shows components of the expansion assembly 40 (detail D3 in Figure 4) and the cutout portion 50 of the cover element (detail D4 in Figure 5), which are essential components of the venting device and will now be described in more detail with reference to Figures 4-4b and 5-6a, respectively. FIG. 4 shows detail D3 of FIG. 1 , i.e., the components of the expansion assembly. These are a second skin 42 surrounding a second gas space 47 and an associated gas generator 48 for filling this second gas space. Such an expansion element 40 is described in detail, for example, in WO 2014 / 029473 A1. The second skin 42 (often referred to as a “microbag”) has a first layer 43 and a second layer 44 in the area of ​​the second gas space 47, with these two layers connected to each other at an edge region 46 (see, in particular, FIG. 4 a). The second skin 42 is preferably manufactured in a one-piece weaving process. Furthermore, at least one of the two layers of the second skin, here the first layer 43, preferably has a gas-permeable vent region 43 a, so that gas can escape from the second gas space 47 after it has been filled. The edge region 46 is preferably relatively wide and, as will be seen later, a seam is arranged which extends through this edge region 46 but not through the second gas space 47 .

[0029] As is known in the art, a gas generator 48 protrudes into the second skin through an opening therein (FIG. 4b), thereby filling the second gas space upon ignition. The gas generator is typically in the form of a pyrotechnic ignition element ("squib").

[0030] Figure 5 shows detail D4 from Figure 1, i.e., cutout 50 of the cover element of the ventilation device. Figure 5 depicts dotted fold lines along which cutout 50 is folded to form folded cover element 52 (see Figures 6 and 6a). The folding results in folded cover element 52 having at least three layers in part (Figure 6a).

[0031] Next, we will discuss the installation of the airbag 5. The primary inflator is typically placed on or in the first skin after the airbag is fully assembled, which is not shown here.

[0032] 7, in one assembly step, the expansion assembly 40, i.e. its second skin 42, is fastened to the inner surface 20b of the second layer 20 in the region of the bulge 22 by an assembly seam 60. The assembly seam 60 does not pass through the second gas space 47, but extends only through the edge region 46 of the second skin. This assembly seam serves primarily as a preliminary fastening and can be replaced by alternative connection techniques, such as gluing.

[0033] The folded cover element 52 is placed on the outer surface 10a of the first layer 10 so that the slit-shaped opening 14 is completely covered and the edge region of the folded cover element 52 is flush with the edge region of the first layer 10 where the slit-shaped opening 14 terminates. A U-shaped cover element seam 62, which serves as a cover element connection, is used for fastening. The lateral legs 62a, 62b of the U extend outward from the fold line, and the transverse leg 63c of the U, of course, extends across the entire width of the folded cover element. Thus, the cover element is held in its folded form by the cover element seam (i.e., by the transverse leg 63c) but can still unfold. In the edge region, the cover element is not connected to the first layer by the cover element seam 63, resulting in an open region O.

[0034] In the next production step (see FIG. 9), the cut portion 5′ of the first skin 5 is folded along the fold line so that the first layer 10 and the second layer 20 lie on top of each other. As a result, the slit-shaped penetration 14 now lies partly on the expansion element 40.

[0035] In a next step, an edge seam 64 is applied as an edge connection connecting the edges of the two layers 10, 20 to one another, thus enclosing the first gas space (in the embodiment shown, together with the fold line F). It is important that the edge seam does not cross the penetration 14 and close the opening area O, which is achieved in the embodiment shown by the edge seam 64 having two portions 64a and 64b that also extend through the edge area 46 of the second skin. Furthermore, the edge seam 64 should not extend through the second gas space 47. The edge seam 64 after installation is shown in Figure 10.

[0036] In a final step (FIG. 11), a tear seam 66 is placed, which cuts the two portions 64a and 64b of the edge seam and the two lateral legs 62a, 62b of the cover element seam 62, thereby closing the opening area O so that gas cannot flow from the first gas space through the space between the first layer and the cover element through the opening area. This tear seam 66 also penetrates the second gas space 47.

[0037] This results in the layer structure shown diagrammatically in FIG. 13. The second skin 42, also partially two-layered, is located between the first layer 10 and the second layer 20, and the cover element 52, partially three-layered, is located on the outer surface 10a of the first layer 10. It is important to note which layers the seams described above extend through; only the tear seam 66 extends through all layers and also crosses the second gas space 47. Note that the cover element seam 62 connects only the outer edge of the cover element 52 to the first layer 10, thereby allowing the lateral legs 62c of the U-shaped cover element seam 62 to extend through all layers of the cover element (this is not shown in FIG. 13). Portions of the edge seam 64 extend through both layers 10, 20 and the edge region 46 of the second skin 42. This assembly seam connects the edge region of the second skin 42 to the second layer 20.

[0038] When the gas generator is ignited, the second skin 42 expands and the tear seam is broken in the area of ​​the second skin 42. This frees the opening area O, opens the originally slit-shaped penetration 14, and causes the cover element 52 to bulge, allowing gas to escape from the first gas space through this penetration and the opening area (Figures 14 and 15).

[0039] 16 to 21 show an exemplary embodiment of the second embodiment of the present invention, which differs from the first embodiment in that the active ventilation device is not located in the edge region of the first layer, and in particular does not extend to the edge.

[0040] As can be seen in Figure 16, the second embodiment consists of the same components as the first embodiment, except that the penetrations in the first layer are designed and positioned differently, as can be seen, for example, in Figures 16 and 17. As in the first embodiment, the penetration has a first slit-shaped portion 14 extending from a first end 14a. However, this first slit-shaped portion 14 does not extend to the edge, but terminates at a second end 14b. From there, a second slit-shaped portion 15 preferably extends perpendicularly, so that the penetration is T-shaped. The second slit-shaped portion "replaces" (with respect to the vent device) the opening edge region of the first embodiment.

[0041] 18, similar to the first embodiment, the folded cover element 52 is initially positioned on the outer surface 10 of the first layer 10 by the cover element seam 62 so as to cover the first slit-shaped portion 14. The front end of the cover element 52 is essentially aligned with the second slit-shaped portion 15 of the penetration.

[0042] Here, the expansion assembly 40 is positioned on the inner surface of the first layer 10 so that its second skin 42 can be fastened to the first layer by an attachment seam 60. With respect to the first embodiment, the inflator end of the expansion assembly is further away from the penetration (shifted to the right in the selected view).

[0043] Finally, a tear seam 66 is positioned (as in the first embodiment), extending through the first slit-shaped portion 14. Since there are no edge seams in the area of ​​the ventilation device, the tear seam 66 completely surrounds the second slit-shaped region 15 and is located in the second skin 42 to separate the second slit-shaped region 15 from the first gas space. Figure 22 shows an alternative design of the tear seam 66, here designed as a zigzag seam, to which the second slit-shaped portion 15 is directly sewn.

[0044] In a second embodiment, the second layer of the first skin is not included in the ventilation device, so that the folding of the joint cuts and placement of the edge seams occurs after the ventilation device has been produced.

[0045] 23 to 29 show variants of the second embodiment. The differences lie in the shape of the penetration, as well as the shape of the cover element 52 and the number of folds. As can be seen, for example, in FIG. 24, the penetration also has two slit-shaped portions 14 and 15, but these do not form a T-shape, but rather a V-shape, which also forms a gap. In this context, it should be mentioned that other shapes of penetration are of course also possible, such as, for example, a U-shape.

[0046] As can be seen in Figure 25, the cover element 52 follows the V-shape of the penetration by decreasing its width towards the tip of the V (i.e. towards the opening area O). As can be seen in Figure 27, the assembly seam 60 and tear seam can be designed as in the embodiment of Figure 20. Figure 29 shows this variant.

[0047] The operation mode is the same as in the first embodiment.

[0048] The above-described embodiments demonstrate all the advantages of the venting device according to the invention, namely that it is simple to manufacture, changes from a first state to a second state almost instantaneously when the gas generator is activated, and can achieve a completely sealed first state and a highly vented second state. [Explanation of symbols]

[0049] 5. First Skin 5' First skin joint cut 10 First Layer 10a: Outer surface of the first layer 10b Inner surface of first layer 12 Outer layer of the first layer (to be precise, the outer edge of the first layer) 14 Slit-shaped penetration in first layer / first slit-shaped portion of penetration in first layer 14a Inner end of slit-shaped penetration / first end of first slit-shaped portion 14b second end of the first slit-shaped portion 15 Second slit-shaped portion of penetration 20 Second Layer 20a Outer surface of second layer 20b Inner surface of second layer 22 Second layer bulge 30 Main inflator 40 Extended Assembly 42 Second Skin 43 First Layer of Second Skin 43a Ventilation area 44 Second Layer of Second Skin 46 Edge region of second skin 47 Second gas space 48 expansion element gas generator 50 Cutting of cover element 52 Cover Elements 60 Assembly Seam 62 Cover element seam 64 Edge seam 66 Tea Seam F fold line O Opening area

Claims

1. An airbag, a first skin (5) surrounding a first gas space, the first skin (5) having a first layer (10) with an inner surface (10b) facing said first gas space and an outer surface (10a) facing away from said first gas space; an active ventilation device having a first throttled or closed state and a second open state, - a penetration (14) in said first layer (10); a cover element (52) arranged on the outer surface (10a) of the first layer (10), at least partially covering the penetration (14) and permanently connected to the first layer (10) by a cover element connection (62), the cover element connection (62) being not closed, so that an open area (O) is formed between the first layer (10) and the cover element (52); an expansion assembly (40) comprising a second skin (42) enclosing a second gas space (47) and a gas generator (48), said second skin (62) being arranged on said inner surface (10b) of said first layer (10) and at least partially overlapping said cover element (52); an active ventilation device comprising a tear seam (66) having a portion that extends through said cover element (52), said first layer (10) and said second skin (42), thus preventing or limiting leakage of gas through said opening area (O) in said first state of said ventilation device.

2. 2. The airbag according to claim 1, wherein the penetration (14) comprises at least one slit-shaped portion (14).

3. 3. Airbag according to claim 1 or 2, characterized in that the cover element (52) is folded and at least partially formed in at least three layers.

4. - said first skin (5) further comprises a second layer (20); - said ventilation device is arranged in the edge region of said first layer (10); - said penetrations (14) extend to said edge of said first layer (10); An airbag according to any one of claims 1 to 3, characterized in that the first layer (10) is permanently connected to the second layer (20) along its edge by an edge connection (64), at least in the area of ​​the ventilation device where the penetration (14) terminates at the edge, without any permanent connection.

5. 5. The airbag of claim 4, wherein a portion of the second skin (20) projects beyond the edge of the first skin, whereby this portion is located outside the first gas space.

6. 6. The airbag of claim 5, wherein the second layer (20) has a bulge (22), and the portion of the second skin (42) located outside the first gas space and the bulge (22) at least partially overlap.

7. 7. The airbag according to claim 4, wherein the second skin (42) is connected to the second layer (20) by an attachment connection (60) that connects only the second skin (42) and the second layer (20).

8. An airbag according to any one of claims 1 to 3, characterized in that the venting device is spaced from the edge of the first layer.

9. 9. Airbag according to claim 8, characterized in that, as far as claim 3 is concerned, the penetration is T-shaped or V-shaped with two slit-shaped portions (14, 15) or U-shaped.

10. An airbag according to any one of claims 1 to 9, characterized in that only the tear seam (66) extends through the second gas space (47).

11. Airbag according to any one of claims 1 to 10, characterized in that at least one layer (43) of the second skin is at least partially gas permeable.

12. An airbag unit comprising: an airbag according to any one of claims 1 to 9; and a main inflator (30) for filling the first gas space.

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