WO2022248447A1

WO2022248447A1 - Airbag with an adaptive ventilation device

Info

Publication number: WO2022248447A1
Application number: PCT/EP2022/064006
Authority: WO
Inventors: Laurent Hellot; Laurent BROGGINI; Fryderyk CHODOROWSKI; Wojciech Gidzinski; Malgorzata Wasilewska; Dorota JAKUBOWSKA
Original assignee: Autoliv Development Ab
Priority date: 2021-05-26
Filing date: 2022-05-24
Publication date: 2022-12-01
Also published as: DE102021113620A1

Abstract

An airbag (5) comprising a ventilation device is described. This airbag (5) has an outer skin (10) with a first opening (12). An additional layer (14) having a second opening (16) at least partially overlapping the first opening (12) is provided and a flap (20) being located between the outer skin (10) and the additional layer (14) at least in sections. Further, a tether element (30) for controlling the flap (20) is provided. This tether element (30) has having a first end portion (31) being attached to the flap (20), a second end portion (36), and a middle portion (34) connecting the first end portion (31) and the second portion (36). In order to improve the gas tightness and the reproducibility, at least a part of the middle portion (34) of the tether element (30) is guided in a tunnel extending along a section of the outer skin (10).

Description

Airbag with an adaptive ventilation device

Description

The invention relates to an airbag having an adaptive ventilation device according to the preamble of claim 1 and to an airbag module comprising such an airbag according to claim 14.

Airbags with an adaptive ventilation device are well known in the automotive technology. Usually, such an adaptive ventilation device comprises a hole in the outer skin of the airbag and a flap. This flap (and thus the ventilation device) has at least a first state and a second state such that the coverage of the hole in the second state is different from the coverage in the first state. It is further known to control this flap by means of a tether element.

Form generic WO 2020 011 634 A1 it is known to arrange the flap between a section of the outer skin of the airbag and an additional layer, wherein both, the outer skin of the airbag and the additional layer have an opening. When the airbag is deployed and the tether element is under tension, the flap covers at least one of the openings at least partially such that the ventilation device is in a closed or throttled first state, and when the airbag is deployed and the tether element is not under tension, the flap covers this opening less than in in the first state, such that the ventilation device is in a second state. The flap is substantially triangle-shaped and the tether extends from one apex of this triangle. The tether element has a first end portion being attached to the flap, a second end portion and a middle portion connecting the first end portion and the second end portion. This type of an adaptive ventilation device and especially the triangle-shape of the flap turned out as working very well. Starting from this prior art it is an object of the invention to further improve a generic ventilation device.

This task is solved by means of an airbag having the features of claim 1 . An airbag module comprising such an airbag is defined in claim 14.

According to the invention, at least a part of the middle portion of the tether element is guided in a tunnel extending along a section of the outer skin. By means of this tunnel, the position of the tether element is clearly defined in all states of the airbag, meaning in its folded state, during deployment and in the deployed state. This has several advantages: First of all, the defined position of the tether element can lead to improved gas tightness in the first state of the adaptive ventilation device. Further, it is surely prevented that the tether element gets caught by another element of the airbag module during deployment of the airbag.

In one embodiment, the tunnel is formed by the section of the outer skin along which the tunnel extends, and a tunnel layer attached to the outer skin of the airbag by means of a first attachment connection and a second attachment connection, such that a minimum of additional material is needed.

In this case it can be preferred that the tunnel layer is a section of the additional layer.

It can be further preferred that a section of the edge (14a) the tunnel layer forms a tunnel outlet for the tether element (30) and that this section of the edge (14a) is concave-shaped. By this measure, the friction between the tether element and the tunnel layer can be reduced, especially if at least the portion of the tether that extends through that tunnel outlet is in form of or comprises a strand.

In another embodiment, the tunnel is formed by a tunnel element forming a sleeve being attached to the outer skin. In this embodiment, the tunnel is displaceable rel- ative to the outer skin by a small amount. In some geometries this can be an advantage.

In the just mentioned embodiment, the tunnel element is usually closed by means of a closing connection, for example a closing seam. This closing connection can also connect the sleeve to the outer skin such that only one connection needs to be generated. Alternatively, the sleeve can be connected to the outer skin by an additional connection other than the closing connection. In some cases, this can ease the production, since the sub-assembly comprising the tether element and the sleeve can be prefabricated.

In order to reduce the friction inside the tunnel it is preferred that at least the middle portion of the tether element is made from at least one strand having an essentially circular or oval cross section, such that it has a small surface.

To ensure an even force transmittal between the tether element and the flap - especially in the just mentioned case of an essentially circular or oval cross section - it is further preferred that the first end portion comprises a first end section and a second end section wherein both end sections are connected to the flap, and wherein the end sections preferably define a first angle larger than 0°, more preferably larger than 30°, and even more preferably between 45° and 90°. In this case, the middle portion is preferably comprised of two parallel sections, wherein each of those sections is one-parted with an end section and even more preferably, the tether element comprises a joint strand with the end sections being the end sections of said joint strand such that the second end portion is loop-shaped and can easily be attached to an attachment means.

An especially preferred application of the invention is an airbag module comprising an attachment means to which the second end portion is releaseably attached, such that the ventilation device can be controlled actively. The invention will now be described by means of preferred embodiments in view of the figures. The figures show:

Figure 1 all parts of a first embodiment of an airbag which are relevant for the invention as well as a connection element which is used for an airbag module comprising the inventive airbag,

Figure 2 the flap and a tether element formed from the strand shown in Figure 1 after a first assembly step,

Figure 3 the additional layer and the cutting for a tunnel element shown in Figure 1 after another assembly step,

Figure 4 the sub-assembly shown in Figure 2 after another assembly step, namely after sewing the flap to the outer skin of the airbag,

Figure 5 what is shown in Figure 4 after the sub-assembly of Figure 3 has been sewn to the outer skin, Figure 6 a cutting along plane A-A in Figure 5,

Figure 6a a variation to what is shown in Figure 6,

Figure 6b another variation of what is shown in Figure 6,

Figure 6c a variation of what is shown in Figure 6b, Figure 7 a schematic representation of the complete airbag module in a state in which the airbag is fully deployed and its ventilation device is in its closed first state, Figure 8 what is shown in Figure 7 after the ventilation device has transferred to its open second state by means of de-attaching the second end portion of the tether element from the fixed part of the connection element,

Figure 9 a cutting for a flap of a second embodiment, Figure 10 the flap folded from the cutting of Figure 9 and the tether element being attached to it,

Figure 11 an alternative to the cutting shown in Figure 9, Figure 12 a second embodiment of the additional layer, Figure 13 a third embodiment of the additional layer, and Figure 14 a fourth embodiment of the additional layer, Figure 15 the elements (except the outer skin) of another embodiment of a ventilation device according to the invention,

Figure 16 the flap, the Y-shaped connecting element, and the pliable member shown in Figure 15 being sewn together via a single seam to form a sub-assembly,

Figure 16a a sectional view taken along plane A-A in Figure 16, and Figure 17 the ventilation device being manufactured from the elements shown in Figure 15. Figure 1 shows - strongly schematic - all relevant elements of a first embodiment of the inventive airbag as well as a connecting element which can be used in an airbag module comprising this airbag.

The airbag comprises - of course - an outer skin 10, from which only a section is shown in Figure 1. A first opening 12 is provided in this outer skin 10. This first opening 12 has a circular shape and this will often be preferred, but is not mandatory. Further, an additional layer 14 is provided; the cutting for this additional layer 14 is also shown in Figure 1. The cutting for this additional layer 14 has a second opening 16 which can have the same size and shape as the first opening 12. The additional layer 14 has an essentially triangular part in which the second opening 16 is provided and a connection part extending from this substantially triangular part. Further, a cutting for a flap 20 is provided. In the first embodiment, this flap and its cutting are identical and are comprised exclusively of an essentially triangular-shaped main portion, such that for the first embodiment the terms “cutting for flap” “flap” and “main portion of flap” can be used interchangeably. The triangle- shape of the flap 20 is similar to the triangular shaped part of the additional layer 14, but is smaller than this part. Since the cutting/ flap 20 is essentially triangular it has of course a first edge 21a and a second edge 21b which enclose a first angle a between 30° and 70°. Since the flap 20 is essentially triangle-shaped, the first edge 21a and the second edge 21b are connected by a third edge 21c. A cutting for a tunnel element 25 forming a tunnel layer has the same width as the connection part of the additional layer 14. It would also be possible to provide a single cutting for the additional layer and the tunnel layer, but for practical reasons it will often be preferred to provide two cuttings as shown. The outer skin 10 and the cuttings 14, 20 and 25 can all be made from the same type of material, especially a woven plastic material which is typically used for producing airbag cushions. Finally, a strand 30’ for a tether element is provided. In the first embodiment, this strand 30’ is in form of a rope having an essentially circular cross section. Of course, this strand 30’ extends for a first to a second end. Although not belonging to the airbag as such, a connecting element 50 is schematically shown in Figure 1. This connecting element 50 can be a part of an airbag module comprising the airbag made from the items described above in order to attach a second end of a tether element made from the strand 30’ to a housing in a releasable manner. This connection element 50 can for example be of the type described in DE 10 2011 014 869 B4. This connection element 50 comprises a fixed part 52 and a breakable part 54 (including a pyrotechnic strip) as it is described in detail in the just mentioned DE 10 2011 014869 B4.

In order to form the tether element 30, the first end section 32 of the strand 30‘ is sewn to the flap 20 along the first edge 21a of the flap 20 by means of a seam 42 and the second end section 33 of the strand is sewn to the cutting 20 along the second edge 21 b of the flap 20 by means of a seam 43, such that the first end section 32 and the second end section 33 also enclose the first angle a (Fig. 2). By this attachment process a first end portion 31 of the tether element 30 is created. This first end portion 31 is Y-shaped and includes a connection portion 31a which consists of the both end section 32 and 33 that are sewn to the flap 20 as just mentioned. This shape of the first end section 31 and especially its connection portion 31a leads to an even force distribution when the tether element is under tension and thus to a flat and well-closing flap. Additionally, a breakage of a seam, the tether element or the flap is prevented.

From this first end portion 31 a middle portion 34 of the tether element 30 extends in which two sections of the strand 30’ are parallel to one another. The second end portion 36 of the tether element following the middle portion 34 is loop-shaped and formed by the middle section of the strand. In the embodiment shown, inter-tether connections 38 are provided between the first end portion 31 and the middle portion 34 and between the middle portion 34 and the second end portion 36.

As is shown in Figure 3, the tunnel element 25 is sewn to the additional layer 14 by means of a seam 44. In the next step, the flap 20 is sewn to the outer skin 10 by means of a seam 45 extending along the third edge 21c of the flap 20 (Fig. 4).

Finally, the sub-assembly being comprised of the additional layer 14 and the tunnel element 25 is sewn to the outer skin 10. In this embodiment, this is done by a single seam 46. This sub-assembly covers the flap 20 and at least a part of the middle portion 34 of the tether element 30. The outcome of this is shown in Figures 5 and 6.

Although it is preferred to use a rope with an essentially circular cross section as a strand for the tether element (see Figure 6), it would also be possible to use a ribbon-shaped element for forming the tether element (Figure 6a) such that a doublelayered main section is formed. In this case, the two layers could be attached to one another by means of a seam.

As one can easily see from Figures 6 and 6a, the tunnel in which at least a part of the middle portion 34 of the tether element is guided can be formed between the tunnel element 25 and the outer skin 10 of the airbag being connected to one another by means of a first section 46a and a second section 46b of the seam 46. These two sections form a first and a second attachment connection. In another embodiment shown in Figure 6b, the tunnel could also be formed by the tunnel element 25 alone defining a sleeve. In this case the tunnel element forms a closed loop closed by a seam 47 forming a closing connection. The sleeve can be connected to the outer skin 10 by means of an additional seam 46 forming an additional connection. In a further alternative embodiment also having a sleeve forming the tunnel, the seam 47 forming the closing connection also connects the sleeve to the outer skin (Fig. 6c).

Figure 7 shows the airbag 5 just described as a part of an airbag module. The airbag module further comprises a housing 60, an inflator 62, and the connection el- ement 50 by means of which the loop-shaped second end portion 36 of the tether element 30 is connected to the housing 60. This connection element serves as attachment means. In the shown embodiment, the additional layer 14 is located on the inner side of the outer skin 10, but it would also be possible to locate the additional layer 14 on the outer surface of the outer skin 10. As is known from the prior art, the flap 20 is located between the outer skin 10 and the additional layer 14 and blocks the gas flow through the first opening 12 and the second opening 16 as long as it is held in place by means of the tether element 30. Most of the tether element 30 is guided in the tunnel which is formed by the tunnel element 25 and a section of the outer skin 10 (or in the variant of Figure 6b formed by the tunnel element alone), such that the position of the tether element is clearly defined. The loopshaped end section 36 of the tether element is held by the breakable part 54 of the connection element 50 as is for example known from DE 10 2011 014 869 B4. In this state the tether element 30 is under tension when the outer skin of the airbag is fully deployed.

If now the loop-shaped second end portion 36 is released, the tether element loses its tension and the flap 20 is pressed out of the first opening 12 and gas can stream out of the interior of the airbag 5, as is known in the prior art.

As has already been mentioned, it will often be preferred to use a rope-type strand for the tether element, especially because it causes much less friction in the tunnel. A drawback of such a rope-type strand is that it usually is less stretchable than a ribbon-type strand. So, when the airbag deploys, the peak tension stress is higher than in a ribbon-type strand. Depending on the overall geometry, additional measures must be taken in order to safely avoid a breakage. The second embodiment of the flap which is described now is especially useful for an airbag using a tether element made of a robe-type strand with low elasticity:

Figures 9 and 10 show a second embodiment of a flap 20. In contrast to the first embodiment, this flap 20 and its cutting 20’ are not identical, because a portion of the flap is multi-layered, namely three-layered. The cutting 20’ for the flap 20 has thus four sections, namely a section 20a’ for the main portion 21 and three sections 20b’ to 20d’ for a protruding portion. In a first step the sections 20c’ and 20d’ are folded onto a middle section 20b’ of the protruding portion such that the flap 20 comes into the shape shown in Figure 10 in which it has a substantially triangular main portion 21 and an also substantially triangular protruding portion 22. This protruding portion 22 is - as mentioned - multilayered. The main portion 21 has the same function as the flap 20 of the first embodiment, namely covering the openings 12, 16 in the outer skin 10 and in the additional layer 14. So, its shape is essentially the same as in the first embodiment and the first end section 32 of the tether element 30 is sewn along the first edge 21a and the second end section 33 of the tether element 30 is sewn along the second edge 21b. The protruding portion 22 is also used for sewing the tether element to the flap 20. So, the tether element 30 comprises a first additional connection section 32a extending from the first end section 32 and a second additional connection section 33a extending from the second end section 33. Those additional connection sections 32a, 33a, extend along the fourth and fifth edge 22a, 22b of the protruding portion 22 and thus enclose a second angle b which is smaller than the first angle a. By means of this geometry and the fact that the protruding section is multi-layered, the lack of elasticity of the rope-type strand can be compensated and a breakage of any of the involved elements can be prevented.

Figure 11 shows a variation of the cutting 20’ shown in Figure 9. The flap which is generated from this cutting 20’ is only double-layered in the protruding portion, meaning that the cutting 20’ has only two sections 20b’, 20c’ for this protruding portion.

In some cases, it might not be necessary to provide a multi-layered protruding portion: The shape of the flap 20 providing an elongated portion for attaching the tether alone can be useful. Further, the protruding portion, especially a double-layered as shown in Figure 11 , can replace a separate tether element. In this case, the protruding portion forms the tether element.

As is shown in Figure 12 it can be preferred to divide the hole 16 by means of a bridge 18 extending substantially perpendicular to the direction of the tether element in order to limit deformations. In the case that the additional layer 16 is located on the inner surface of the outer skin of the airbag, this bridge is an integral part or is attached to this additional layer 16, in case that the additional layer is located on the outer surface of the outer skin, this bridge would cross the hole in the outer skin of the airbag and would thus be a part of the outer skin or be attached to it. The outer hole should be free from such a bridge in order to allow the flap to pass through it.

Figures 13 and 14 show other possibilities how the inner hole can be stabilized: As shown in Figure 13, the hole can be non-circular and as is shown in Figure 14, a seam 19 can extend around the hole. All these stabilization measures can be used alone or in any combination and can also be applied to ventilation devices not showing a tunnel and/ or not showing a tether element of the described type.

In view of the Figures 15 to 17 a further embodiment of the ventilation device is described. Figure 15 shows all parts (except the outer skin with its first opening) in an unassembled state. As in the first embodiment, the ventilation device comprises a cutting for an additional layer 14, a cutting for a flap 20 as in the first embodiment, the flap is identical to its main portion), and a strand 30 of the tether element which forms a playable member of this embodiment. Additionally, this embodiment comprises a Y-shaped connecting element 39 of the tether element and a C- shaped member 49. In this embodiment the tunnel layer is a section of the additional layer 14 and consequently no separate tunnel element is provided. One difference to the embodiments described so far is that the tether element 30, namely its first end portion 31 is comprised of two elements, namely the just mentioned Y-shaped connecting element 39 and the strand 30’ which forms a pliable member of the tether element. The Y-shaped connecting element is a flat cutting (for example consisting of airbag material) and comprises two legs 39a, 39b.

As in the first embodiment, the strand 30’ is folded such that the middle portion of the tether element is comprised of two parallel sections of the strand 30’. Another difference is that (as mentioned) the tunnel layer is a section of the additional layer 14. As can be seen from Figure 15, the additional layer 14 is dropshaped in this embodiment such that it tapers towards the outlet of the tunnel.

As one can also see from Figure 15, the edge 14a at the tether outlet (this can also be seen in Figure 17) is concave because it turned out that this helps to reduce the friction of the tether element, namely its pliable member.

Finally, the C-shaped reinforcement member 49 is provided, which has no counterpart in the embodiments described so far.

In one production step (please see Figures 16 and 16a) the Y-shaped attachment element 39 and the strand 30^' forming the pliable member are sewn to the flap 20 to form a sub-assembly. This is preferably done by a single seam 40 connecting the pliable member (strand 30’), the Y-shaped attachment element 39 and the flap 20. It is to be noted that in this embodiment (and this is preferred) that the end sections 31, 32 of the tether element are exclusively formed by the legs 39a, 39b of the Y-shaped attachment element 39, not by the ends of the strand 30^'. This makes the attachment process easier and more reproducible. In a final assembly step the subassembly shown in Figure 16, the C-shaped reinforcement member 49 and the additional layer 16 are sewn to the outer skin of the airbag (not shown) by means of a single seam 40. The C-shaped reinforcement member is located on the end of the arrangement distal the tunnel outlet. At this location, the arrangement is four-layered with the outer skin, the flap 20, the additional layer 14 and the reinforcement member 49 or even five-layered with the out- er skin, the flap 20, a leg 39a, 39b of the attachment element 39, the additional layer 14 and the reinforcement member 49.

One can here even better see that the tunnel outlet formed by the edge 14a is concave. In the embodiments shown, all connections are seams which is often preferred, but it needs to be mentioned that other types of connections like gluing ort welding could also be used at least for some of the connections.

List of reference numbers

5 airbag

10 outer skin

12 first opening (opening in outer skin)

14 additional layer / cutting for additional layer

14a edge at tether outlet

16 second opening (opening in additional layer)

18 bridge

19 seam around opening

20 cutting for flap / flap 20’ cutting for flap 20a’ section of main portion 20b’-d’ sections of protruding portion 21 flap / main portion of flap 21a first edge 21b second edge 21c third edge 22 protruding portion 22a third edge 22b fourth edge 25 tunnel element / cutting for tunnel element

30 tether element 30’ strand of tether element / pliable member

31 first end portion 31a connection portion

32 first end section 32a first additional connection section

33 second end section 33a second additional connection section

34 middle portion 36 loop-shaped second end portion

38 inter-tether connection

39 Y-shaped attachment element of tether element 39a first leg 39b second leg

40 seam connecting pliable member and Y-shaped attachment element

42-49 connections (seams)

49 C-shaped reinforcement member

50 connecting element 52 fixed part

54 breakable part with pyrotechnic squib 60 housing 62 inflator 64 retainer ring a first angle b second angle

Claims

1 . Airbag (5) having a ventilation device, comprising: an outer skin (10) of the airbag, said outer skin (10) having a first opening

(12), and an additional layer (14) having a second opening (16) at least partially overlapping the first opening (12), a flap (20) being located between the outer skin (10) and the additional layer (14) at least in sections, a tether element (30) having a first end portion (31) being attached to the flap (20) at least in sections, a second end portion (36), and a middle portion (34) connecting the first end portion (31 ) and the second portion (36), characterized in that at least a part of the middle portion (34) of the tether element (30) is guided in a tunnel extending along a section of the outer skin (10).

2. Airbag according to claim 1 , characterized in that the tunnel is formed by the section of the outer skin (10) along which the tunnel extends and the tunnel layer (25) is attached to the outer skin (10) of the airbag by means of a first attachment connection and a second attachment connection.

3. Airbag according to claim 2, characterized in that the tunnel layer is a section of the additional layer (14).

4. Airbag according to claim 2 or claim 3, characterized in that a section of the edge (14a) the tunnel layer forms a tunnel outlet for the tether element (30) and that this section of the edge (14a) is concave-shaped.

5. Airbag according to claim 1 , characterized in that the tunnel is formed by a tunnel element (25) forming a sleeve being attached to the outer skin.

6. Airbag according to claim 5, characterized in that the tunnel element (25) is closed by means of a closing connection.

7. Airbag according to claim 6, characterized in that the closing connection also connects the sleeve to the outer skin.

8. Airbag according to claim 6, characterized in that the sleeve is connected to the outer skin by an additional connection other than the closing connection.

9. Airbag according to any one of the preceding claims, characterized in that at least the middle portion of the tether element is made from at least one strand having an essentially circular or oval cross section.

10. Airbag according to any one of the claims 1 to 9, characterized in that the first end portion (31) comprises a first end section (32) and a second end section (33) wherein both end sections (32, 33) are connected to the flap (20), wherein the end sections (32, 33) preferably define a first angle larger than 0°, more preferably larger than 30°.

11. Airbag according to claim 10, characterized in that the tether element (30) comprises a pliable member and a Y-shaped attachment element (39), wherein at least the Y-shaped attachment element (39) comprises the first end section (32) and the second end section (33) of the tether element (30).

12. Airbag according to claim 10 or to claim 11 , characterized in that the flap (20) comprises a triangle-shaped main portion (21) with a first edge (21a) and a second edge (21 b), wherein the first end section (32) extends along the first edge (21a) and the second end section (33) extends along the second edge (21b).

13. Airbag according toany one of claims 10 to 12, characterized in that the middle portion (34) is comprised of two parallel sections.

14. Airbag according to claim 13, characterized in that the tether element (30) comprises a joint strand (30’) such that the middle portion (34) is comprised of two parallel sections of the joint strand (30’).

15. Airbag according to one of claim 14, characterized in that the second end portion (36) is a loop-shaped.

16. Airbag according to any one of claims 1 to 15, characterized in that a stabilisation means is provided for the inner of the first and the second hole, said stabilisation means comprising at least one of: a bridge crossing the opening, a seam encircling the opening and a non-circular cross-section of the opening.

17. Airbag module comprising the airbag of any one of claims 1 to 16 and an attachment means to which the second end portion is releaseably attached.