The invention relates to an airbag according to the preamble of claim 1 , to a method for producing such an airbag according to claim 7, to an airbag unit according to claim 8, to an airbag arrangement according to claim 9 and to a vehicle seat according to claim 10.

The invention especially relates to an airbag for being mounted to the backrest of a vehicle seat such that a part of this airbag serves as side airbag deploying laterally of an occupant’s upper body, but is not limited to that.

A traditional side airbag comprises a first layer and a second layer being connected via an edge connection such that at least parts of the two layers enclose a gas space. This gas space can be sub-divided into a plurality of chambers, such that the airbag can be said to comprise a plurality of parts, each of those parts enclosing a chamber. Such an airbag can be produced very economically since it has a “2D-structure” meaning that the two layers and the edge connection are in one plane during all the production process. Such an airbag can be produced in the one-piece-woven technique or at least a part of the edge connection must be applied separately, mostly in form of an edge seam.

A drawback of such side airbags is that they essentially keep their “2D-structure” also when deployed. This means that they can only protect the side of the person to be protected and that they usually need an external support (for example the side structure of the vehicle). Starting from that prior art this invention sets itself the task to provide an airbag that is essentially as easy to produce as a traditional side airbag but whose possibilities of application exceed the possibilities of a traditional side airbag.

This task is solved by an airbag having the features of claim 1 . A preferred method for producing such an airbag is defined in claim 7, an airbag unit comprising such an airbag is defined in claim 8, an arrangement of such an airbag unit in a vehicle seat is defined in claim 9 and a vehicle seat unit comprising a vehicle seat and such an airbag arrangement is defined in claim 10.

Like a common side airbag, the airbag according to the invention comprises a first layer, a second layer, and an edge connection connecting the two layers such that at least parts of the first layer and the second layer enclose a gas space. Both layers comprise a first area having a first outer border, a second area having a second outer boarder, and a third area having a third outer boarder. The respective areas of the two layers are usually congruent to each other. The first area of the first layer and the first area of the second layer form a first part of the airbag enclosing a first chamber of the gas space, the second area of the first layer and the second area of the second layer form a second part of the airbag enclosing a second chamber of the gas space, and the third area of the first layer and the third area of the second layer form a third part of the airbag enclosing a third chamber of the gas space.

Further, each layer comprises first inner connection area and a second inner connecting the first area, such that that also the airbag comprises a first inner connection area and a second inner connection area of the airbag, wherein the first inner connection area of the airbag connects the first part of the airbag and the second part of the airbag, and a second inner connection area of the airbag connects

(i) the first area of the airbag and the third area of the airbag or

(ii) the third area of the airbag and the second area of the airbag.

Each inner connection area shows an overflow between the neighbored chambers. According to the invention, in the case of (i) a section of at least one of the second outer boarders and a section of at least one of the third outer boarders are connected via at least one additional connection, and in the case of (ii) a section of at least one of the first outer boarders and a section of at least one of the third outer boarders are connected via at least one additional connection. Because of this, the deployed airbag is bent along the inner connection areas and forms a three dimensional, self-supporting structure, especially such that in the deployed state the first outer boarders define a first plane, the second outer borders define a second plane and the third outer boarders define a third plane. Those planes preferably enclose angles between 45° and 90°.

In order to form hinges along which the airbag easily bends, it is preferred that each inner connection area of the airbag comprises at least one non-inflatable area.

In one preferred embodiment the edge connection is closed, in another preferred embodiment it comprises an opening for inserting an inflator.

In a preferred method for manufacturing such an airbag, first a precursor of the airbag is manufactured. This precursor comprises the first layer, the second layer being arranged on top of the first layer and the edge connection. In a subsequent step, the additional connection is applied.

Of course, the airbag according to the invention is usually processed to an airbag unit further comprising an inflator. Since - as will be described later - the first part of the airbag preferably forms a side airbag, this inflator is in most cases located inside the first chamber enclosed by the first part.

In a preferred airbag arrangement, the airbag unit is attached to a vehicle seat, especially to the backrest of a vehicle seat. The first part of the airbag then forms a side airbag extending laterally of at least a section of the torso of a person sitting in the vehicle seat when the airbag is deployed. Further, the second part extends over the shoulder of this person and the third part extends in front of at least a sec- tion of the torso of this person, or the third part extends over the shoulder of this person and the second part extends in front of at least a section of the torso of this person. One main advantage is that the part forming a frontal airbag (either the second part or the third part) does not need an external support surface due to the self-supporting properties of the inventive airbag. The second main advantage is that the part of the airbag extending over the shoulder can keep the neck from bending too far by restraining the head.

The invention will now be described in more detail by means of preferred embodiments in view of the figures. The figures show:

Figure 1 : a first cutting forming a first layer of the airbag of the first embodiment,

Figure 2: a second cutting forming a second layer of this airbag,

Figure 3: the second layer of Figure 2 after it has been laid on top of the first layer and an edge seam forming an edge connection has been applied, such that an airbag precursor is formed,

Figure 4: the precursor shown in Figure 3 after turning around the precursor, wherein the positions of the additional seam are indicated,

Figure 5: a completely manufactured airbag, namely the precursor shown in Figure 4 after the additional seam has been applied,

Figure 6: substantially the airbag shown in Figure 5 in a deployed state,

Figure 7: what is shown in Figure 6 vied from another angle,

Figure 8: substantially the deployed airbag shown in Figure 6 in a state mounted to a backrest of a vehicle seat and a person sitting in this vehicle seat, Figure 9: substantially the same as shown in Figure 7,

Figure 10: a schematic representation of a second embodiment of the invention essentially in a representation according to Figure 4,

Figure 1 1 : a third embodiment of the invention in a representation according to Figure 10,

Figure 12: a single cutting comprising a first layer and a second layer of a fourth embodiment of the inventive airbag,

Figure 13: the single cutting of Figure 12 after it has been folded along its folding line and the edge connection seam has been applied, such that a precursor is generated,

Figure 14: the completely mounted airbag of the fourth embodiment, namely the items shown in Figure 13 after the additional seam has been applied, and

Figure 15: a variation to what is shown in Figure 13.

The structure of the inventive airbag is now described by means of various embodiments. In most of those embodiments, only the structure of the outer skin of this airbag is shown and described. Thus, the terms “airbag” and “outer skin of airbag” are sometimes used interchangeably. Despite that it is to be noted that a complete airbag can comprise more parts, especially inner tethers, outside tethers, reinforcement layers, inner gas guiding elements and the like. As an example, an inner tether will be shown in view of the fourth embodiment.

Figures 1 and 2 show a first layer 10 and a second layer 20 of the airbag (the outer skin of the airbag) in a schematic representation showing all details necessary for understanding this invention. In this first embodiment, these two layers 10, 20 are in form of separate cuttings, but as will especially be seen in view of a fourth embodiment, they could also be sections of a single cutting intended for being folded around a folding line.

The two layers 10, 20 of the first embodiment of the airbag are substantially congruent with one exception: The first layer 10 shows holes 18 for inflator studs and an opening 19 for insertion of an inflator. Both layers 10, 20 comprise a first area 11 , 21 , a second area 12, 22 and a third area 13, 23. Of course, each area has an outer boarder, said outer boarders being referred to as first outer boarder, second outer boarder, and third outer boarder. First areas 11 , 21 and second areas 12, 22 are connected via first inner connection areas 15, 25 and first areas 11 , 21 and third areas 13, 23 are connected via second inner connection areas 17, 27. As can directly be seen from the drawings, the inner connection areas each comprise indentions 15a, 17a, 25a and 27a at both ends thereof. Providing such indentions is usually preferred although not strictly mandatory. According to the definitions chosen in this application, the indentions form non-inflatable areas.

In one production step the two layers 10, 20 are placed on top of one another and an edge connection seam 30 is applied (Figures 3 and 4). In this embodiment this edge connection seam 30 alone forms the edge connection and is closed, such that the two layers 10, 20 and the edge connection 30 completely enclose the gas space of the airbag. Of course, other types of edge connections like bondings, weldings or the like could be used but a seam is most common. As will be seen later in view of the fourth embodiment, a part of the edge connection can also be in form of a fold. Further, the edge connection could be in form of an one-piece- woven (OPW) connection.

Additionally, a first hinge connection seam 31 connects the first inner connection area 15 of the first layer 10 with the first inner connection 25 of a second layer 20 and a second hinge connection seam 32 connects the second inner connection area 17 of the first layer 10 and the second inner connection area 27 of the second layer 20 such that inner non-inflatable inflatable areas 31 a and 32a are generated in the inner connection areas of the airbag. The first inner non-inflatable area 31 a is in line with the indentions 15a, 25a and the second inner non-inflatable area 32a is in line with the indentions 17a, 27a, such that hinges are created.

The airbag (in this stage called “precursor” 3) is now almost ready and one can see that it comprises a first part 41 - comprising the first part 1 1 of the first layer 10 and the first part 21 of the second layer 20 - enclosing a first chamber, a second part 42 - comprising the second part 12 of the first layer 10 and the second part 22 of the second layer 20 - enclosing a second chamber and a third part 43 - comprising the third part 13 of the first layer 10 and the third part 23 of the second layer 20 - enclosing a third chamber. The first part 41 is connected to the second part via the first inner connection 35 of the airbag comprising the first inner connection 15 of the first layer and the first inner connection 25 of the second layer and to the third part 43 via the second inner connection 37 of the airbag comprising the second inner connection 17 of the first layer 10 and the second inner connection 27 of the second layer 20. The first chamber is connected with the second chamber via two overflows 31 b next the first non-inflatable area 31 a and the first chamber is connected to the third chamber also via two overflows 32b next to the second non- inflatable area 32a. The overflows 31 b are (of course) located in the first inner connection area 35 and the overflows 32b are (of course) located in the second inner connection area 37.

In a final production step the second part 42 and the third part 43 of the airbag are connected to one another by means of an additional connection in form of an additional seam 34. The positions of this additional seam 34 along a section of the second outer borders 34c and a section of the third outer border 34c are indicated in Figure 4.

Figure 5 shows the result of this in a state in which the airbag is not inflated but folded along the hinges defined by the first inner connection area 35 and the second inner connection area 37, such that a three-dimensional structure is generated in which each of the parts 41 , 42 and 43 defines a plane. In the embodiment shown, the angle between the plane of the first part 41 and the plane of the third part 43 is about 90°, the angle between the plane of the second part 42 and the plane of the third part 43 is also about 90° and the angle between the plane of the first part 41 and the plane of the third part 43 is about 60°. Since the airbag and especially its outer skin of course is comprised of a traditional and thus flexible airbag material, the airbag can be folded flat (such that all parts are located basically in one plane) but this cannot be done along the hinges of the connection areas.

As a consequence, the airbag 5 “automatically” deploys to a three-dimensional structure when filled with gas since in this state the airbag can only bend along its predefined hinges. The deployed state is for example shown in Figures 6 and 7. The angles between the planes of the three parts are substantially as described above, but since most areas of the outer skin of the airbag cushion are convex in the deployed state, the planes are defined exclusively by the outer boarders which remain essentially flat.

In Figure 8 the deployed airbag as shown in Figure 6 is shown in a state when mounted to the backrest 64 of a vehicle seat 60. An inflator 50 is located inside the first part 41 and is attached to the frame of the backrest, for example in a traditional manner by means of inflator studs extending through the holes 18, such that the inflator also attaches the airbag 5 to the backrest 64 of the vehicle seat 60. An Indirect attachment of the inflator to the backrest, for example via brackets, is of course also possible.

The first part 41 extends substantially in the X-Z-plane like a traditional side airbag along at least a part of the torso of a person P sitting in the vehicle seat 60. The second part 42 extends from the upper end of the first part 41 over the shoulder of the occupant and the third part 43 forms a frontal airbag being located in front of at least a part of the torso of the occupant P. Because of the three-dimensional structure, the airbag 5 is to a large extent “self-supporting” and especially the frontal part (here the third part 43) does not need a support surface like an instrument panel or a steering wheel. Although only one airbag unit is shown in Figure 8, it is possible to provide such an airbag unit at both sides of the seat, such that the first part of a first airbag deploys left of the person and the first part of a second airbag deploys right of the person.

Figure 10 shows a second embodiment in a representation substantially as in Figure 3, but without showing the edge connection seam 30.

Like in the first embodiment, the first inner connection area 35 extends between the first part 41 and the second part 42, but the second inner connection area 37 extends between the second part 42 and the third part 43. Further, the additional seam (or other additional connection) connects sections of the first outer borders 34a and the third outer borders 34c. The positions of this additional seam are indicated via the reference numbers 34a and 34c.

Like in the first embodiment, in a common application the first part 41 forms a side airbag, the second part 42 forms a part extending over the shoulder and the third part 43 forms a frontal airbag and, also as in the first embodiment, the inflator is located in the first part 41 . The difference to the first embodiment is mainly that the airbag shows a serial deployment behavior with the third part 43 deploying last (in the first embodiment the second part 42 and the third part 43 deploy essentially at the same time).

In Figure 11 a third embodiment is shown which also has a serial configuration. According to the definition chosen in this application the first part 41 forms the side airbag part (like in all embodiments), the second part 42 forms the frontal part and the third part 43 forms the part extending over the shoulder. Taking this into account, the structure is like in the second embodiment: The first inner connection 35 extends between the first part 41 and the second part 42 and the second inner connection 37 extends between the second part 42 and the third part 43; the additional connection (additional seam) connects a section of the first outer border 34a and a section of the third outer border 34c. In this embodiment the frontal airbag part is deployed before the shoulder airbag part. So, one sees that despite the fact that the fully deployed airbag has the same shape in all of the first three embodiments, the deployment behavior can be chosen.

Figures 12 to 14 show a fourth embodiment in a representation which is a little more detailed. The main difference is that the outer skin of the airbag is made from a single cutting 7 meaning that the first layer 10 is a first section of this single cutting and the second layer 20 is the second section (in Figure 12 the left section). In contrast to the first embodiment, the two sections of the single cutting are not 100% congruent, because the second section comprises an additional mounting area 29 which is outside the edge connection seam 30 (see Figure 13).

It is also to be observed that the positions of the additional seam are here in form of protruding areas which makes the sewing process easier.

Figure 13 shows the situation after folding the single cutting 7 along the folding line FL and applying the edge connection seam 30. The complete edge connection is here comprised of this edge connection seam 30 and the fold F between the two sections. The edge connection is not completely closed, because an opening 19 for insertion of the inflator remains that can in this embodiment be closed by a closing section 8 of the single cutting 7; Figure 13 shows this. Additionally, an inner tether 70 is also shown in Figure 13.

Figure 14 shows the completely assembled airbag, including the additional seam 34. Once sees, that when the airbag is folded flat, the folding is not along the hinges defined by the inner connection areas. In the geometry of this embodiment the precursor 3 needs to be folded along two lines of folding LF, but in other geometries only one line of folding LF might be sufficient. This structure of this embodiment could of course also be applied to the geometry of the second and the third embodiment.

Figure 15 shows a variation to the fourth embodiment. Here, only one layer has protrusions for the additional seam. List of reference numbers

3 precursor

5 airbag

7 single cutting for outer skin of airbag

8 closing section for closing the opening for insertion of the inflator

10 first layer /first section of joint cutting

11 first area of first layer

12 second area of first layer

13 third area of first layer

15 first inner connection area of first layer

15a indention (part of non-inflatable area)

17 second inner connection area of first layer

17a indention (part of non-inflatable area)

18 hole for inflator studs

19 opening for insertion of inflator

20 second layer I second section of joint cutting

21 first area of second layer

22 second area of second layer

23 third area of second layer

25 first inner connection area of second layer

25a indention (part of non-inflatable area)

27 second inner connection area of second layer

27a indention (part of non-inflatable area)

29 additional mounting area

30 edge connection seam (edge connection)

31 , 32 hinge connection seam

31 a inner non-inflatable area

31 b overflow

32a inner non-inflatable area

32b overflow

34 additional seam (additional connection)

34a position of additional seam at first areas 34b position of additional seam at second areas

34c position of additional seam at third area

35 first inner connection area of airbag

37 second inner connection area of airbag 41 first part of airbag enclosing first chamber

42 second part of airbag enclosing second chamber

43 third part of airbag enclosing third chamber

50 inflator

60 vehicle seat 62 seating

64 backrest

66 headrest

70 inner tether

F fold FL folding line

LF line of folding

P person sitting in vehicle seat