WO2009018884A1

WO2009018884A1 - An adhesive bonded airbag for motor vehicles

Info

Publication number: WO2009018884A1
Application number: PCT/EP2008/005456
Authority: WO
Inventors: Detlev Guthke; Helmut Maiwald
Original assignee: Delphi Technologies, Inc.
Priority date: 2007-08-03
Filing date: 2008-07-03
Publication date: 2009-02-12
Also published as: EP2020344A1; EP2020344B1

Abstract

The invention relates to an airbag for motor vehicles comprising an airbag envelope (13) having at least one adhesive bond (19,31) by which material layers of the airbag envelope are adhesively bonded to one another, wherein the adhesive bond is made in linear or strip form and extends such that stresses of the adhesive bond occurring on the inflation of the airbag and with an inflated airbag are distributed over the length of said adhesive bond such that stress peaks are avoided.

Description

008/005456

Delphi Technologies, Inc. D 10419PWO - Jr

AN ADHESIVE BONDED AIRBAG FOR MOTOR VEHICLES

The invention relates to an airbag for motor vehicles comprising an airbag envelope which has at least one adhesive bond by which material layers of the airbag envelope are adhered to one another.

In airbags of this type, the adhesive bonds serve, for example, to close the airbag envelope, on the one hand, and to form chambers within the airbag envelope, on the other hand, which are largely separately from one another in a technical flow aspect and to which the gas made available by a gas generator is distributed via a gas distributor for the inflation of the airbag.

Generally, i.e. independently of the respective purpose of the adhesive bond, the spacing of the material layers tends toward zero at the adhesive points, which brings about relatively high loads on the adhesive points. To design the adhesive bond as simply as possible from a technical flow aspect, the material layers contact one another simply areally in the region of the adhesive points. A so-called "peeling" stress hereby results for the adhesive points on the inflation of the airbag and with an inflated airbag which can result in a release of the adhesive connection - i.e. in a separation of the mutually adhesively bonded material layers either with or without destruction of one or both material layers - even with relatively low loads. To increase the load capacity of the connection points, the material layers of the airbag envelope are therefore additionally sewn to one another in practice. The adhesive bonds are therefore reinforced or secured by one or more seams. In connection with connections of material layers provided for the formation of chambers, one also speaks of so-called "darts", and indeed in allusion to the seams additionally connecting the material layers to one another. By the combination of adhesive bonding, on the one hand, and sewing, on the other hand, the demands nowadays made on airbags can in particular easily be satisfied with respect to the load capacity. These demands are in particular determined by the inflation conditions and, in this context, above all by the temperature of the gas flowing into the airbag on inflation and by the gas pressure prevailing inside the airbag on inflation. However, in the mentioned known types of connection, the relatively high production costs are disadvantageous which result in that two different manufacturing steps, which cost approximately the same, are required with the adhesive bonding and the sewing.

It is the object of the invention to provide an airbag which can be manufactured as cost effectively as possible and which simultaneously satisfies all the demands made in practice.

This object is satisfied by the features of claim 1.

Provision is made in accordance with the invention for the adhesive bond to be made in linear form or in strip form and to extend such that stresses of the adhesive bond occurring on the inflation of the airbag and with an inflated airbag are distributed over the length of said adhesive bond such that stress peaks are avoided.

The invention makes use of the recognition not predictable for the person of ordinary skill in the art that it is not the peeling stress of the adhesive bonds per se which sets relative low limits for their load capacity, but rather that the load capacity is substantially increased by adhesive bonds which are not reinforced or secured by seams or other measures if the adhesive bonds have a suitable extent and e.g. extend from margin to margin or from connection region to connection region (see below), i.e. do not end "at the middle of the airbag" or - in other words - not with a spacing from a marginal region or from a connection region of the airbag envelope such as is the case e.g. with known darts of airbags divided into a plurality of chambers to enable a flowing over of the gas from chamber to chamber.

It has been found that, e.g. by adhesive bonds extending from margin to margin or by adhesive bonds which extend between regions or points of the airbag envelope at which the material layers of the airbag envelope are connected to one another in one piece or by other means, stress peaks or tension peaks can be avoided which result in a reduction of the load capacity of the adhesive bonds. In order to nevertheless allow the gas to enter into the individual chambers in the case of an airbag with a plurality of chambers which are separated from one another by one or more separation adhesive bonds, an at least partly inwardly disposed gas distributor can be provided. In this further development of the invention, an inwardly disposed gas distributor and one or more "throughgoing" adhesive bonds, i.e. adhesive bonds extending from marginal region to marginal region or from connection region to connection region of the airbag envelope, are consequently combined with one another.

It has been found that, if the principle in accordance with the invention of avoiding stress peaks is consistently applied, additional securing seams can be completely dispensed with. All the required connections between the material layers can thus be realized by adhesive bonding. It must, however, be emphasized in this connection that the invention is not restricted to airbags exclusively including adhesive bonds. The invention rather also includes e.g. those arrangements in which seams are provided in addition to the adhesive darts, in particular seams which are short in comparison with the length of he separation adhesive bonds and which can provide additional reinforcement or security of the adhesive bond at specific points or can serve for other purposes.

An advantage of the possibility provided by the invention of working with seam-free adhesive bonds comprises forming the adhesive bonds directly as "desired separation points" at which the connection between the material layers releases in a controlled manner without the material layers being damaged and the airbag becoming leaky when loads occur which exceed a predetermined degree. If e.g. it is ensured that a marginal adhesive bond closing the airbag envelope withstands those loads which result in a releasing of one or more separation adhesive bonds, it can be achieved by the embodiment of the separation adhesive bonds in accordance with the invention that the separation adhesive bonds can release on an excessive load and thus the airbag can yield in a controlled manner to such a load, with the retention function of the airbag being maintained. An excessive load can e.g. be caused by an excessively high temperature and/ or an excessively high gas pressure which the separation adhesive bonds are exposed to on inflation by the inflowing gas. "Release of the adhesive bond" is to be understood here such that the mutually adhesively bonded material layers are not destroyed, but are maintained, i.e. that so-to-say the adhesive medium releases or disintegrates or is separated or torn. A controlled separation of the material layers previously adhesively bonded to one another can thus be achieved.

Possible embodiments of the invention are also set forth in the dependent claims, in the description and in the drawing. In a possible embodiment of the invention, provision is made for the adhesive bond to be provided in the form of a closed line or of a closed strip or for the adhesive bond to start and end in region or at points of the airbag envelope at which the material layers of the airbag envelope are connected to one another. It is in particular hereby avoided that the adhesive bond ends "in the middle of the airbag", that is in regions at which the material layers of the airbag envelope lie on one another or contact one another without connection in the uninflated state. The adhesive bonds are consequently lines or strips which "never end", i.e. there is no "end point" at which forces could engage and cause excessive stresses or strains for the adhesive bonds. The adhesive bonds thus extend free of end points or without a free end point, i.e. without an engageable end point.

The adhesive bond can be a separation adhesive bond which forms an adhesive dart separating two chambers of the airbag envelope from one another and is formed between material layers of the airbag envelope bounding the chambers or it can be a marginal adhesive bond by which material layers of the airbag envelope are adhesively bonded to one another to close the airbag envelope in regions which are marginal regions of the spread out airbag envelope with an uninflated airbag. An airbag in accordance with the invention can have both one or more such separation adhesive bonds and also at the same time one or more such marginal adhesive bonds.

Provision can furthermore be made for the airbag envelope to be divided into a plurality of chambers and to include a gas distributor which is located at least partly in the airbag envelope and via which gas generated by a gas generator for the inflation of the airbag can move into the chambers, with the chambers being separated from one another by at least one adhesive dart which includes a linear or strip-shaped separation adhesive bond which is formed between material layers of the airbag envelope bounding the chambers and extends between two regions which are marginal regions of the spread out airbag envelope with an uninflated airbag.

The separation adhesive bond in particular extends in a straight line, with this, however, not being compulsory. However, a separation adhesive bond not extending in a straight line preferably has an only slight curvature, and indeed in the sense of a consistent application of the principle of avoiding stress peaks wherever this is possible and sensible.

Provision can be made for the spacing between the material layers of the airbag envelope adhesively bonded to one another along the separation adhesive bond also to tend toward zero on the inflation of the airbag and with an inflated airbag.

In a possible embodiment, the gas distributor is included in the separation adhesive bonding.

Provision can furthermore be made for the gas distributor to be formed by at least one flexible and /or bendable material layer.

Material layers of the airbag envelope bounding the chambers can be adhesively bonded to one another in at least one first section and to at least one material layer forming the gas distributor in at least one second section for the formation of the adhesive dart.

A further embodiment proposes that the separation adhesive bond has at least one branch at which a first section, along which material layers bounding the chambers are adhesively bonded to one another, merges into a second section which includes at least two part sections, along which at least one respective material layer bounding the chambers is adhesively bonded to at least one material layer forming the gas distributor.

Provision can furthermore be made for the material layers to be arranged in the region of the separation adhesive bond such that the separation adhesive bond is substantially only exposed to a peeling load on the inflation of the airbag and with an inflated airbag.

In accordance with an embodiment, material layers of the airbag envelope are adhesively bonded to one another by at least one marginal adhesive bond for the closing of the airbag envelope in regions which are marginal regions of the spread out airbag envelope with an uninflated airbag.

The marginal regions can in particular extend in linear or strip shape.

In accordance with a further development, it is possible that the material layers are arranged at least regionally in the region of the marginal adhesive bond such that the marginal bond is substantially only exposed to a shearing load on the inflation of the airbag and with an inflated airbag.

Adhesive bonds onto which shearing forces act can be exposed to higher loads than adhesive bonds which are loaded in a peeling manner before the adhesive bond releases. Separation adhesive bonds loaded in a peeling manner can thus be used in connection with a marginal adhesive bond loaded in a sheering manner, said adhesive bonds loaded in a peeling manner being configured in dependence on expected loads such that they release in a controlled manner before the airbag therefore becomes leaky, because e.g. the marginal adhesive bond releases or the airbag envelope yields to the respectively acting load at a different point.

Provision can be made for the material layers to be brought into a shearing load configuration at least regionally in the region of the marginal adhesive bond by single or multiple flipping over, turning over and/ or folding of at least one material layer.

Provision is furthermore made in accordance with a further development for the airbag envelope to include at least two material layers which are disposed above one another with an uninflated airbag and a spread apart airbag envelope with mutually facing inner sides, with a marginal region of the one material layer being flipped over, turned over and /or folded around a marginal region of the other material layer and being bonded at its inner side to the outer side of the other material layer at least regionally for the formation of the marginal adhesive bond.

Such an "engaging around" or "wrapping around" of the one material layer by the other material layer is, however, not compulsory. Alternatively, a marginal region of the one material layer can be flipped over, turned over and/ or folded for the formation of the marginal adhesive bond without the inclusion of the other material layer such that the marginal region is then adhesively bonded at its inner side to the inner side of the same material layer and at its outer side to the inner side of the other material layer. A marginal adhesive bond with a shearing load also hereby arises.

In accordance with a further embodiment, the spread out airbag envelope has a basic shape with an uninflated airbag whose marginal region is formed at least in regions closed by a marginal adhesive bond only by straight sections and/ or - with the exception of optionally provided corner regions - slightly curved sections.

Such an embodiment in turn represents a consistent application of the principle of avoiding stress peaks and thus permits a further simplification and thus a cost reduction in the manufacture of the airbag.

Furthermore, the separation adhesive bonding can be configured such that, when a presettable load dependent on the inflation conditions is exceeded, the connection between the mutually adhesively bonded material layers releases while maintaining the gas tightness of the airbag envelope.

The gas distributor is arranged close to the margin in accordance with an embodiment.

The gas distributor can be made in hose form, in pipe form or in passage form.

Furthermore, the gas distributor can be provided with a plurality of gas discharge openings of which at least two do not open into the same chamber.

The invention additionally relates to an airbag module for motor vehicles having at least one inflatable airbag in accordance with the invention and at least one gas generator for the inflation of the airbag.

The invention will be described in the following by way of example with reference to the drawing whose only Figure schematically shows an embodiment of an airbag module in accordance with the invention in a side view and two cross-sectional views.

The airbag module includes an airbag envelope 13 shown in the spread out state and a gas generator 17. The airbag envelope 13 includes two material layers 21, 23 which have substantially the same shape and the same size and which are adhesively bonded to one another for the formation of the airbag envelope 13 in a manner explained in more detail below.

Furthermore, an inwardly disposed gas distributor 15 or passage is provided which includes a material layer 25 and in integrated into the airbag envelope 13 or forms a component of the airbag envelope 13. The layers 21, 23 of the airbag envelope 13, on the one hand, and the layer 25 of the gas distributor 15 can consist of the same material or of different materials. The gas distributor 15 can be a separate component which is connected to the material layers 21 , 23 of the airbag envelope on the manufacture of the airbag. Alternatively, the gas distributor 15 can be formed by a section of at least one material layer 21 , 23 of the airbag envelope 13 correspondingly cut to size.

The gas distributor 15 is made in hose shape and is arranged directly at a marginal region of the airbag envelope 13 as can in particular be seen from the sectional representations A-A and B-B. A kind of pocket 43 is formed outside the airbag envelope 13 at this marginal region and can be formed by a separate material layer or by at least one material layer 21, 23 of the airbag envelope 13 correspondingly cut to size. The pocket 43 serves for the reception of a gas generator 17 which projects beyond the pocket 43 into the gas distributor 15. The gas generator 17 is made thrust- neutral in this embodiment, i.e. the gas flows out of the ejector end of the gas generator 17 located inside the gas distributor 15 in opposite directions into the gas distributor 15.

The material layers 21, 23 of the airbag envelope 13 are connected to one another at the marginal region of the airbag envelope 13 at the top in the Figure, that is at the marginal region at which the gas distributor 15 is arranged here, with this being able to be done either by generally any- desired connection means or with the material layers 21, 23 also being able to be connected to one another in one piece, i.e. the airbag envelope 13 includes a single piece of material which is folded over at the upper marginal region for the forming of the material layers 21, 23.

The gas distributor 15 is provided with a multiple of gas outlet openings 39 which are arranged such that each of a plurality of chambers 11 of the airbag can be supplied with gas practically simultaneously. In the embodiment shown, three chambers 11 are provided, with the left hand and right hand chambers 11 each being able to be filled with gas via a respective one of the end faces of the gas distributor 15 provided with one or more gas outlet openings 39, whereas the middle chamber 11 is in communication with the gas distributor 15 via a plurality of gas outlet openings 39 which are formed in the jacket surface of the gas distributor 15. A section of the airbag provided between the middle chamber 11 and the right hand chamber 11 forms a passive region 41 which is not filled with gas on the inflation of the airbag.

The formation of the chambers 11 in the airbag envelope 13 and of the airbag envelope 13 per se takes place by adhesive bonding of the respective material layers. A marginal adhesive bond 31 is provided in the marginal region for the closing of the airbag envelope 13. The material layers 21, 23 are disposed on one another in a simple area! manner in the corner regions 37 and are adhesively bonded to one another in linear or strip shape. These regions of the marginal adhesive bond 31 are consequently exposed to a peeling stress on loading, i.e. on the inflation of the airbag and with an inflated airbag. The straight-line regions 35 of the airbag boundary are formed in a different manner: One material layer 21 is provided with strip- shaped tabs 45 which are flipped over for the establishing of the airbag envelope 13and are folded over the other material layer 23 such that the inner sides of the tabs 45 are disposed on the outer side of the other material layer 23 and can be adhesively bonded to it. The straight- line regions 35 of the marginal adhesive bond 31 are consequently exposed to a shearing stress on loading.

The material layers 21, 23 are either connected to one another by any desired means, e.g. by adhesive bonding and/or by sewing at the marginal region which is at the top in the Figure and at which the gas distributor 15 and outwardly - at least regionally - the pocket 43 for the gas generator 17 are located or the material layers 21, 23 form sections of a single material layer which are formed in one piece with one another, said material layer being used for the manufacture of the airbag envelope 13 after a corresponding cutting to size and being folded to form the two (part) layers 21, 23.

Since the stress of the marginal adhesive bond 31 is less in the corner regions 37 under load than in the straight line regions 35, the marginal adhesive bond 31 can be exposed to comparatively high loads due to the shearing load configuration provided in the straight-line regions 35, i.e. the sealing tightness of the airbag envelope 13 is also ensured at relatively high loads. As the Figure shows, the shape or contour of the spread out airbag envelope 13 can be selected such that, with the exception of the corner regions 37, only straight-line or slightly curved regions 35 are present which can be brought relatively simply into a shearing load configuration in the manner explained above. The load capacity of the airbag can consequently be increased by a skilful selection of the airbag contour.

For the formation of the chambers 11 of the airbag envelope 13, a plurality of linear or strip-shaped separation adhesive bonds 19 are provided at which the material layers 21, 23 of the airbag envelope 13 are - as in the corner regions 37 - only adhesively bonded to one another disposed on one another and which are consequently exposed to a peeling stress under load. The separation adhesive bonds 19 extend from marginal region to marginal region while including the gas distributor 15 such that no adhesive darts are present which end inside the airbag volume and an overflowing of gas from chamber 11 to chamber 11 is not possible. The gas can consequently only enter into the chambers 11 via the gas distributor 15 and can therefore not enter into the passive region 41 of the airbag envelope 15 which is thus not also inflated.

As the cross-sectional representation B-B shows, the two respective material layers 21, 23 of the airbag envelope 13 are directly adhesively bonded to one another in a first section 27 of the separation adhesive bonds 19 so that the mutual spacing of the material layers 21, 23 tends toward zero at the adhesive darts. A second section of the separation adhesive bonds 19 includes two respective part sections 29a, 29b in which a respective one of the material layers 21, 23 of the airbag envelope 13 is connected to the material layer 25 of the gas distributor 15. The separation adhesive bonds 19 consequently have a branch at the gas distributor 15, with it having been found that the load capacity of the separation adhesive bonds 19 is considerably larger than originally expected in the region of the branches.

The separation adhesive bonds 19 exposed to a peeling stress under load are less loadable than the marginal adhesive bond 31. When the separation adhesive bonds 19 release due to a load exceeding a specific degree without destruction or damage of the material layers, the airbag nevertheless remains gastight and thus generally operable - however, without the original camera division - since the marginal adhesive bond 31 continues to withstand the load and thus a protective gas volume continues to be available. As already initially mentioned, a controlled yielding of the airbag can thereby be realized in that the separation adhesive bonds 19 are configured so-to-say as "desired separation points".

In the embodiment shown here, the material layers 21, 23 are rounded in the corner regions 37 such that they substantially follow the shape of the marginal adhesive bond 31. Less material consequently remains outside the marginal adhesive bond 31. Deviating from this embodiment, the corner regions 37 can be made angled, as is indicated in the Figure by the example of the top right corner by a dashed line. The additional material, i.e. the material tab hereby arising, can be utilized for the tying of the airbag in the vehicle, for example for guy lines or other fastening devices.

It must furthermore be mentioned that the airbag is here shown as a so- called center module in which the inflation by the gas generator 17 takes place in a central region - viewed in a direction from the front to the rear. Alternatively, the airbag can also be a so-called end fill module in which the gas generator is arranged at least slightly remote from the airbag at the end of a gas line, e.g. in the form of a tube or of a hose, which extends along the airbag and is provided with gas outlet openings. In a further alternative to the embodiment shown, the airbag can likewise be provided with one or more inwardly disposed passages at its longitudinal side disposed opposite the gas distributor or the passage 15, that is at the lower side in the Figure, which enables an overflowing of gas from one chamber 11 into an adjacent chamber 11. Two respective adjacent chambers 11 are in particular connected to one another by one passage. This permits a balance equalization between the chambers 11. Pressure equalization passages of this type preferably substantially correspond to the gas distributor 15, i.e. they consist of at least one flexible and/ or bendable material layer and are in particular formed as a hose. The shape of the separation adhesive bonds 19 in the region of the pressure equalization passages then preferably corresponds to the shape of the separation adhesive bonds 19 in the region of the gas distributor 15, i.e. the separation adhesive bonds 19 continue to extend from margin to margin.

Reference numeral list

11 chamber

13 airbag envelope 15 gas distributor, passage

17 gas generator

19 separation adhesive bond

21 material layer of the airbag envelope

23 material layer of the airbag envelope 25 material layer of the gas distributor

27 first section of the separation adhesive bond

29a part section of the second section of the separation adhesive bond

31 marginal adhesive bond

33 shearing load configuration

35 straight section of the marginal region

37 corner region 39 gas outlet opening

41 passive region

43 pocket

45 tab

Claims

1. An airbag for motor vehicles comprising an airbag envelope (13) having at least one adhesive bond

(19, 31) by which material layers (21, 23) of the airbag envelope (13) are adhesively bonded to one another, wherein the adhesive bond (19, 31) is made in linear form or in strip form and extends such that stresses of the adhesive bond (19, 31) occurring on the inflation of the airbag and with an inflated airbag are distributed over the length of said adhesive bond such that stress peaks are avoided.

2. An airbag in accordance with claim 1, characterized in that the adhesive bond (19, 31) extends free of an end point or without a free end point.

3. An airbag in accordance with claim 1 or claim 2, characterized in that the adhesive bond (19, 31) is provided in the form of a closed line or of a closed strip; or in that the adhesive bond (19, 31) starts and ends in regions or at points of the airbag envelope (13) at which the material layers (21, 23) of the airbag envelope (13) are connected to one another, in particular by connection means or in one piece.

4. An airbag in accordance with any one of the preceding claims, characterized in that the adhesive bond is a separation adhesive bond (19) which forms an adhesive dart separating two chambers (11) of the airbag envelope (13) from one another and is formed between material layers (21, 23) of the airbag envelope (13) bounding the chambers (11); and/or in that the adhesive bond is a marginal adhesive bond (31) by which material layers (21, 23) of the airbag envelope (13) are adhesively bonded to one another for the closing of the airbag envelope (13) in regions which are marginal regions of the spread out airbag envelope (13) with an uninflated airbag.

5. An airbag in accordance with any one of the preceding claims, characterized in that the airbag envelope (13) is divided into a plurality of chambers (11) and includes a gas distributor (15) which is located at least partly in the airbag envelope (13) and via which gas generated by a gas generator (!7) for the inflation of the airbag can enter into the chambers (11), wherein the chambers (11) are separated from one another by at least one adhesive dart which includes a linear or strip-shaped separation adhesive bond (19) which is formed between material layers (21, 23) of the airbag envelope (13) bounding the chambers (11) and extends between two regions which are marginal regions of the spread out airbag envelope (13) with an uninflated airbag.

6. An airbag in accordance with claim 5, characterized in that the spacing between the material layers (21 , 23) of the airbag envelope

(13) adhesively bonded to one another along the separation adhesive bond (19) also tends toward zero on the inflation of the airbag and with an inflated airbag.

7. An airbag in accordance with claim 5 or claim 6, characterized in that the gas distributor (15) is also included in the separation adhesive bond (19).

8. An airbag in accordance with any one of the claims 5 to 7, characterized in that the gas distributor (15) is formed by at least one flexible and/or bendable material layer (25).

9. An airbag in accordance with any one of the claims 5 to 8, characterized in that material layers (21 , 23) of the airbag envelope (13) bounding the chambers (11) are adhesively bonded to one another in at least one first section (27) and are bonded to at least one material layer (25) forming the gas distributor (15) in at least one second section (29a, 29b) to form the adhesive dart.

10. An airbag in accordance with any one of the claims 5 to 9, characterized in that the separation adhesive bond (19) has at least one branch at which a first section (27), along which material layers (21, 23) bounding the chambers (11) are adhesively bonded to one another, merges into a second section which includes at least two part sections (29a, 29b), along which at least one respective material layer (21, 23) bounding the chambers (11) is adhesively bonded to at least one material layer (25) forming the gas distributor.

11. An airbag in accordance with any one of the claims 4 to 10, characterized in that the material layers (21, 23, 25) are arranged in the region of the separation adhesive bond (19) such that the separation adhesive bond (19) is substantially only exposed to a peeling load on the inflation of the airbag and with an inflated airbag.

12. An airbag in accordance with any one of the preceding claims, characterized in that material layers (21 , 23) of the airbag envelope (13) are adhesively bonded to one another by at least one marginal adhesive bond (31) in regions which are marginal regions of the spread out airbag envelope (13) with an uninflated airbag for the closing of the airbag envelope (13).

13. An airbag in accordance with claim 12, characterized in that the marginal adhesive bond (31) extends in linear form or in strip form.

14. An airbag in accordance with claim 12 or claim 13, characterized in that the material layers (21 , 23) are arranged at least regionally in the region of the marginal adhesive bond (31) such that the marginal adhesive bond (31) is substantially only exposed to a shearing load on the inflation of the airbag and with an inflated airbag.

15. An airbag in accordance with any one of the claims 12 to 14, characterized in that the material layers are brought into a shearing load configuration (33) at least regionally in the region of the marginal adhesive bond (31) by single or multiple flipping over, turning over and/ or folding of at least one material layer.

16. An airbag in accordance with any one of the claims 12 to 15, characterized in that the airbag envelope (13) includes at least two material layers (21 , 23) which are disposed over one another with mutually facing inner sides with an uninflated airbag and a spread out airbag envelope (13), with a marginal region of the one material layer (21) being flipped over, turned over and/or folded around a marginal region of the other material layer (23) at least regionally for the formation of the marginal adhesive bond (31) and its inner side is adhesively bonded to the outer side of the other material layer (23).

17. An airbag in accordance with any one of the preceding claims, characterized in that the spread out airbag envelope (13) has a basic shape with an uninflated airbag whose marginal region is formed at least in regions closed by a marginal adhesive bond only by straight sections (35) and /or - with the exception of optionally provided corner regions (37) - slightly curved sections.

18. An airbag in accordance with any one of the claims 4 to 17, characterized in that the separation adhesive bond (19) is configured such that, when a presettable load dependent on the inflation conditions is exceeded, the connection between the mutually adhesively bonded material layers (21, 23) releases while maintaining the gas tightness of the airbag envelope (13), in particular without any destruction or damage of the material layers (21, 23).

19. An airbag in accordance with any one of the claims 5 to 18, characterized in that the gas distributor (15) is arranged close to the margin.

20. An airbag in accordance with any one of the claims 5 to 19, characterized in that the gas distributor (15) is made in hose form, in tube form or in passage form.

21. An airbag in accordance with any one of the claims 5 to 20, characterized in that the gas distributor (15) is provided with a plurality of gas outlet openings (39) of which at least two do not open into the same chamber (11).

22. An airbag module for motor vehicles comprising at least one inflatable airbag in accordance with any one of the preceding claims and at least one gas generator (17) for the inflation of the airbag.