WO2008008060A1

WO2008008060A1 - Airbag and process for manufacture of an airbag

Info

Publication number: WO2008008060A1
Application number: PCT/US2006/027002
Authority: WO
Inventors: Ian Taylor; Marc Phillips; Yves Puccetti; Alan Bradburn; Christopher Mchugh; Mark Hatfield
Original assignee: Autoliv ASP Inc
Current assignee: Autoliv ASP Inc
Priority date: 2006-07-11
Filing date: 2006-07-11
Publication date: 2008-01-17
Anticipated expiration: 2009-01-11

Abstract

The invention relates to an airbag, in particular an airbag for the head and shoulder area, with a distribution element for gas from a gas generator, to which at least one multi-layer chamber is connected, which can be filled with gas from the gas generator and which is connected from the point of view of flow with outflow openings of the distribution element. The distribution element exhibits an acceptance device for the gas generator. The distribution element is cut out of a basic material and is connected to form a hollow body and the layers of chambers are connected to the distribution element via two opposite connecting tracks.

Description

AIRBAG AND PROCESS FOR MANUFACTURE OF AN AIRBAG

Field of the invention: The invention relates to an airbag, particularly to an airbag for the head and shoulder area, with a distribution element for gas from a gas generator and with at least one inflatable chamber which exhibits at least two layers and is formed in the airbag and can be filled with gas from the gas generator. The gas chamber is connected from the point of view of flow with outflow openings of the distribution element, which exhibits at least one acceptance device for the gas generator and which is connected to the airbag. This type of airbag is particularly located in the roof area of a motor vehicle and serves to protect the head and shoulder area during a side impact or a roll over of a vehicle, and such airbags are also called "inflatable curtains". In other applications this type of airbag can also be located in the vehicle door and unfold upwards.

The invention also relates to a process for manufacturing an airbag, in particular an airbag for the head and shoulder area, with a distribution element for gas from a gas generator and with at least one inflatable, multi-layer chamber, which can be filled with gas from the gas generator and is connected from the point of view of flow with outflow openings of the distribution element, which exhibits at least one acceptance device for the gas generator and which is connected to the airbag.

Background of the invention:

A protective cushion for the head of a vehicle occupant is known from DE 199 39 618 Al which can guide gas into chambers simultaneously or which can guide gas between the chambers with a desired time delay. The cushion includes an inner layer and an outer layer on the vehicle body side, which are located above one another and are sewn together in order to create free chambers between the layers. A cylindrical element is located between the top sections of the layers. Gas which is delivered through a rear end of the cylindrical element is led into the chambers through outflow openings. The cylindrical element as well as the two layers of the chambers are closed with a common seam. A further airbag system is known from WO 2004/050424 A2. Here too, the chambers are formed of fabric pieces which are sewn to form a hollow body by means of a circumferential seam. The distribution element is completely sewn into the airbag.

A disadvantage of the airbag according to the state of the art is the fact that the circumferential seam of the chambers results in a high degree of elasticity and therefore a high leakage rate. Furthermore, the displacement of the filling nozzle to be connected to the gas generator from an outer to a central position also requires modification of the upper connecting seam as well as the upper section of the airbag layers.

The problem of the present invention is to avoid the disadvantages of the state of the art and to provide an improved airbag and a process for its manufacture with which the requirements placed on an airbag during an accident are better fulfilled.

Summary of the invention:

The airbag according to the invention provides for a distribution element for gas from a gas generator as well as at least one inflatable, multi-layer chamber. The chambers can be filled with gas from the gas generator and are connected from the point of view of flow with outflow openings which are provided in the distribution element, preferably near the chambers. The distribution element also provides an acceptance device for the gas generator and is connected to the airbag. The attachment of the distribution element can be done by form closure, by force closure or by adhesive bonding, in particular by sewing, glueing or welding. The distribution element is therefore manufactured using the "cut and sewn" method, where a hollow body is manufactured of a basic part or a section, made from a basic material, by connecting, so that gas from a gas generator can be led through the hollow body. This distribution element is connected to the layers of the chamber via two opposite connecting tracks to form an airbag, wherein the layers of the chamber. The chamber is manufactured using the "one-piece woven" method, which results in increased durability and improved sealing of the chambers, as the fabric layers are no longer joined by means of a sewing, but the join is created using the weaving method. Longer stand-up times can be achieved in the airbag because of the more gas- tight seal of seams of the one-piece-woven chamber which offer improved sealing. Alternatively to the use of fabric material foil or film material can be used for manufacture of the chamber and/ or the distribution element.

A further improvement of the invention is that the layers of the chamber are connected by form closure, by force closure or by adhesive bonding, in particular by sewing, glueing or welding. The distribution element or the hollow body can be formed of two parts, in particular from a membrane and a covering panel, wherein the hollow body being done form covering panel and membrane comprises outflow openings within the membrane, through which gas can flow from the hollow body into the chamber. In case of several chambers the outflow openings enable a simultaneous filling of the chambers with gas from the gas generator, which results in a quick filling behaviour of the air bag.

The membrane can be attached to the layers of the chamber, in particular by sewing, welding or glueing. The membrane is also connected to the second part of the hollow body via respective attachment means. The membrane can be coated, in particular with a thermal activatable coating in order to form a gas tight connection between the covering panel of the hollow body or the distribution element and the layers of the chamber.

An embodiment of the invention is that the membrane and the covering panel are connected to each layer of the chamber via a common connecting track in order to form a connection between the three layers of membrane, covering panel and layer of chamber via a single connecting track, for instance by a sewn seam, a welded seam or a gluing line.

Advantageously the connecting tracks of the layers of the chamber are connected separately to each layer of the distribution element. According to an embodiment a closing track can connect the layers of the distribution element, wherein the closing track is spaced apart from the connecting tracks. . It can be provided that the distribution element exhibits at least one closing track which joins the two layers of the distribution element. In the same way, at least two connecting tracks are present which are at a distance from the closing track and which join the respective separate layers of the chambers with one respective layer of the distribution element. Differently than in the state of the art, therefore, the distribution element is not completely accommodated inside the chamber or chambers of the airbag. Rather, the closing track which connects the layers of the distribution element, which are laid on top of one another, with each other, is implemented separately, so that only a part of the distribution element, most usefully the part with the outflow openings, is arranged inside the chambers or is covered by the layers of the chamber material. This results in reduction of material for the chamber fabric or foil material and reduction of costs. This means that the airbag can be easily adapted to different unfolding characteristics which can be different for each vehicle type and, if appropriate, can differ from one another for each type of vehicle and, if appropriate, depending on the accident or side collision. Furthermore, the position of the inlet portion of the distribution element can be selected at will, without influencing the connecting tracks to the layers of the chambers.

In order to achieve as fast and well-adapted unfolding of the chambers and filling with the gas of the gas generator as possible, several chambers are connected to the distribution element, preferably where a protective effect has to be provided. Within this, it can be useful to attach chambers onto the distribution element separately from one another, so that for example, in the case of the B pillar no chamber volume is to be filled, as no protective function is required there. In order to ensure sufficient stability of the airbag, if separate chambers are provided which are coupled with one another, connecting fabric is provided between the chambers, so that the airbag provides a more or less continuous "curtain". For this simple and cheap fabric material or foil or film can be used.

In a further embodiment of the invention it is provided for that the materials of which the distribution element and the chambers are made exhibit different physical characteristics in order to be able to adapt the airbag optimally to the conditions obtaining at any particular time. Relatively high temperatures and high pressure are implemented in the area of the gas generator, which have to be taken up by the distribution element or which the distribution element has to resist. Correspondingly, the material in this area is provided with a high degree of strength and temperature- resistance, for example by means of a special type of weave, particular yarns or by means of a coating. In the distant areas of the chambers, hot gas will be present at relatively low pressure, so that there, fabric with a lower degree of strength or thinner yarn can be used, so that the airbag is altogether lighter and can be designed to as to be smaller when folded.

In order to achieve improved adaptation of the airbag to the particular conditions of use, the distribution element is formed in several parts, whereby here too, different materials can be used depending on the operating conditions which apply. If, for example, the gas generator is located centrally on the distribution element, it is useful to provide the central area with a very strong, temperature-resistant material, while the edge areas of the distribution element which guide the gas to the chambers through the outflow openings can be manufactured of less stable, lighter and less expensive material. Alternatively, the gas generator can also be connected at one end of the distribution element and the distribution element can be formed in one piece.

One embodiment provides that the connecting tracks with which the chamber is attached to the distribution element extend over the entire length of the chamber or chambers, so that the chamber, which consists of one piece of fabric which is open at the side in order to accept the distribution element, forms a basically closed hollow space along with the connected distribution element, into which gas can be guided through the outflow openings of the distribution element.

It can be provided that the distribution element comprises straps or tabs in order to attach the airbag within the vehicle. The chambers, the distribution element and the membrane can be made from different materials, for instance different kinds of fabric and foil or film material. According to the invention it is provided to manufacture an airbag, in particular an airbag for the head and shoulder area, with a distribution element for gas from a gas generator and with at least one inflatable, multi-layer chamber that can be filled with gas from the gas generator and is connected from the point of view of flow with outflow openings of the distribution element, which exhibits at least one acceptance device for the gas generator and is connected to the airbag, each layer of the chamber is connected to the distribution element via an individual connecting track and the distribution element is closed forming a hollow body. Within this constellation it is possible that the distribution element can be manufactured of one or several material sections which are subsequently connected together. It is also possible to provide only one closing track which is located outside the chambers in order to form the fabric section of the distribution element which is folded once into a hollow body. It can be provided that the hollow body is closed via a single closing track and the connecting tracks are spaced apart from the closing track.

Further it is provided that the chamber is closed with a circumferential track after formation of the closing track.

The closing track, the connecting track and/ or the circumferential track can be done by sewing, glueing or welding, wherein a membrane with outflow openings can be inserted between the layers of the chamber and a covering panel of the distribution element, which is connected to said layers of the chamber and covering panel.

As an alternative to a one-piece woven design of the chambers, it is possible, that after implementation of the closing track the chambers are closed with a circumferential track, so that the chambers are also manufactured together with the distribution element and the complete airbag. In the following text, embodiments of the invention will be explained in more detail by means of the drawings. Brief description of the drawings:

Figure 1 - A birds-eye view of an airbag according to the invention;

Figure 2 - A sectional view along Line II - II;

Figure 3 - An alternative embodiment to Figure 2; as well as

Figure 4 - A cut view of a further embodiment of the invention.

Detailed description of the invention:

Figure 1 shows an airbag 1 with a distribution element 2 which is constructed of three partial elements 2', 2", 2'". The embodiment shown exhibits an acceptance device 5 in the form of an inlet opening for a gas generator not shown here, approximately in the middle of distribution element 2. Two side elements 2", 2'" are sewn onto the middle partial element 2', which together form a distribution lance for the gas produced by the gas generator. The two opposite ends of the distribution lance are closed by seams 37, 38. Outflow openings 22 are formed in the lower area of partial elements 2", 2"", through which the gas can stream into chambers 3, 4. In the embodiment shown, chambers 3, 4 are formed separately in the form of two-layer hollow bodies woven in one piece, which are sewn onto the respective partial elements 2", 2'" by means of connecting seams. Alternatively to the seams other attachment concepts can be used like welding or glueing. Further on the distribution element and the chambers can be manufactured from a foil or film material instead of fabric.

At the top end of distribution element 2 which lies opposite chambers 3, 4, connection points 21 are provided by means of which airbag 1 can be fixed to a roof frame or another part of the vehicle body. In the case of an airbag which lies in front of the window of a motor vehicle, fixing straps 30, 40 are formed on chambers 3, 4 in order to allow connection to parts of the vehicle body. It is provided that the front chamber 4 is connected to the A pillar by means of fixing strap 40 and the rear chamber 3 is fixed to the C pillar by means of fixing strap 30. The gas generator, not shown, and therefore also acceptance device 5 for the gas generator are located in the area of the B pillar. In so far as the gas generator is not located on the B pillar of the vehicle, acceptance device 5 is provided at an end area of distribution element 2.

In the embodiment which is shown, chambers 3, 4 are formed separately and connected by means of a connecting fabric 6, which consists of one layer and is therefore light and inexpensive. Because of connecting fabric 6, which is also located in the area of the B pillar and therefore in an area not to be covered by chambers 3,4, it is possible to cover a continuous surface by means of chambers 3,4 and connecting fabric 6, so that it is possible to effectively prevent chambers 3,4 from folding or flapping out by means of fixing straps 30, 40, if the side window is destroyed, or penetration of objects in the direction of the vehicle occupants can be hindered.

Within chambers 3, 4 sewings or seams 34, 35, 44, 45, 46 are formed which divide chambers 3, 4 into individual inflatable areas. It is possible that the sewings or seams 34, 35, 44, 45, 46 are formed so as to be continuous, so that compartments which are separate from one another are formed in chambers 3,4. Within this, the outflow openings 22 are arranged in such a way that each chamber 3, 4 and, if appropriate, each compartment can be filled as fast as possible.

In Figure 1 it is indicated that the fabric structure of the middle partial element 2' with the acceptance device 5 for the gas generator is different from the fabric structure of the side partial elements 2", 2'". This is indicates by different angular run of the yarns; while in the middle partial element 2' a 45° run of the yams is shown, a right- angular yarn run is provided for in side partial elements 2", 2'". The middle partial element 2' and side partial elements 2", 2'" can also be manufactured of fabrics of different yarn thicknesses.

In Figure 2 it can be seen that chamber 3 is formed of a one-piece fabric, which is sewn onto the side partial element 2'" via connecting seams 31, 32. The fabric of the side partial element 2'" is cut out of a basic fabric and closed so as to form a hollow body by means of a closing seam 20. Connecting seams 31.32 are implemented at a distance from closing seam 20, so that a part of distribution element 2 is located above chambers 3, 4. Only the lower section of distribution element 2 with outflow openings 22 is covered by the fabric of chambers 3, 4, so that two basically hollow bodies are formed by chambers 3,4 as well as side sections 2", 2'" of distribution element 2. Instead of a one-piece form of the side partial element 2'" it is possible to form this of two sections with two closing seams.

An alternative embodiment is shown in Figure 3 in which the closing seam 20 at the same time forms one of the connecting seams, so that only one further connecting seam

32 is necessary in order to connect the distribution element or partial element 2"' with chamber 3 or the corresponding fabric section. In a two-part form of side element 2'" or the distribution element the two connecting seams 31, 32 can form the closing seams at the same time, as shown in Figure 2, so that connecting seams and closing seams are the same.

One possibility of manufacturing an airbag 1 according to the invention provides that connecting seams 31, 32 are implemented first. After this, a first closing seam is formed to connect two layers of distribution element 2 or of side partial element 2'". After this, if necessary, the second closing seam of distribution element 2 or side partial element 2'" is formed. In so far as chamber 3 is also to be manufactured using the cut-and-sewn method, chamber 3 is closed by a circumferential seam while forming a hollow body. If chamber 3 is woven in one piece, the last work step is not carried out.

As an alternative, it is provided for that first only one connecting seam 32 is implemented and that then the second connecting seam is implemented in the form of closing seam 20, as shown in Figure 3, in order to complete airbag 1. By means of the airbag according to the invention it is possible that chambers 3, 4 exhibit a longer lifetime because of their improved sealing qualities if a piece of fabric woven in one piece is used. Because of the lower pressure loads in chambers 3,4 in comparison to the middle partial element 2' it is possible to use non-coated material for chambers 3,4, so that lighter and lower-cost implementation of airbag 1 is possible. The middle partial element 2' of distribution element 2 can be provided with reinforcement or can be manufactured of reinforced fabric, in order to be able to resist the high pressure from the gas generator as well as the high temperatures during unfolding of airbag 1. The side partial elements 2", 2'" are sewn onto the middle partial element 2' and preferably closed at the ends turned away from middle partial element T . The side partial elements 2", 2"' collect the gas which is generated and distribute it to the respective chambers 3, 4. Because of the size of the outflow openings 22 as well as the dimensions of side partial elements 2", 2'" the gas stream can be controlled and therefore the load on the seams in chambers 3, 4 or in the compartments formed in them can be reduced. Chambers 3, 4 themselves can be adapted to the unfolding characteristics which are required in the individual case and can also be woven into a one-section piece of material. The present invention makes possible a combination of coated and non-coated fabrics, whereby reinforcement need only be applied in those areas where it is needed. Elastic seams can be provided in areas of high loads, while woven hems or seams can be provided for areas with low loads and improved lifetimes. Airbag 1 according to the invention can be adapted to the respective application, which means that lighter textiles and thinner yarns can be used, which leads to a reduction in weight and packing size. Such an airbag can also be in the form of a side airbag.

In Figure 4 a cut view through an airbag 1 with a chamber 50 is shown, which is formed from two layers 51, 52 of a fabric or foil material. The layers 51, 52 can be connected to each other via sewing 53 or via a welding seam or a glueing seam, respectively a connecting track in order to create a contour and to divide the chamber 50 in several parts.

The upper end of chamber 50 is formed by a membrane 7 that is put on top of the folded upper portions of layers 51 and 52. In the membrane 7 outlet openings 22 are formed through which gas can flow from a not shown gas generator into the chamber 50 and further not shown chambers. The gas flow is shown in Figure 4 by the arrow. On top of the membrane 7 a covering panel 8 is provided that forms together with the membrane 7 a hollow body for accommodation of a gas generator or for guiding of the gas flow coming from the gas generator. Membrane 7 and covering panel 8 forming the distribution element 2. The layers 51, 52, the membrane 7 and the covering panel 8 are connected to each other via connecting tracks 31, 32. The connecting tracks 31, 32 can be formed as sewn seams having separate yarn or alternatively as welded seams or glued seams.

The membrane 7 can be coated on one or both side with plastic or adhesive material. The coating can be thermal activatable, so that a connection of the membrane 7 and layers 51, 52 and also the covering panel 8 is created under heat treatment of the sandwiched layers.

Alternatively the membrane 7 can be uncoated and can be formed from porous material. In such case there is no need for separate outflow openings 22 in order to guide the gas flow into the chamber 50.

The covering panel 8 can be provided with an acceptance device 5 for a gas generator unit that is either located at one of the ends of the distribution element 2 or located in the center thereof (shown schematically in Figure 4).

Also in this embodiment all connections between single layers can be sewn, welded or glued. In a sewing operation the sewn seams can be sealed by for instance a silicone strip which is applied on top of the seam or through which the sewing is done.

Claims

Claims:

1. An airbag, in particular an airbag for the head and shoulder area, with a distribution element for gas from a gas generator and at least one inflatable chamber that is formed so as to have at least two layers in the airbag and that can be filled with gas from the gas generator, the chamber is connected from the point of view of gas flow with outflow openings of the distribution element, which exhibits at least one acceptance device for the gas generator and which is connected to the airbag, the distribution element is cut from a basic material and is connected to form a hollow body, the layers of the chamber are connected to the distribution element via two opposite connecting tracks.

2. An airbag according to claim 1 wherein the layers of the chamber are connected to the distribution element by form closure, by force closure or by adhesive bonding, in particular by sewing, glueing or welding.

3. An airbag according to claim 1 wherein the hollow body is formed from two parts.

4. An airbag according to claim 3 wherein the hollow body comprises a membrane with outflow openings from the hollow body into the chamber.

5. An airbag according to claim 4 wherein the membrane is attached to the layers of the chamber, in particular by sewing, welding or glueing.

6. An airbag according to claim 4 wherein the membrane is coated.

7. An airbag according to claim 6 wherein the membrane comprises a thermal activatable coating.

8. An airbag according to claim 4 wherein the hollow body is formed from the membrane and a covering panel.

9. An airbag according to claim 8 wherein the membrane and the covering panel are connected to the layers of the chamber via a common connecting track.

10. An airbag according to claim 1 wherein the connecting tracks connect the layers of the chamber separately to each layer of the distribution element.

11. An airbag according to claim 1 wherein chambers are formed as to be woven in one piece.

12. An airbag according to claim 1 wherein a closing track connects the two layers of distribution element and that connecting tracks are at a distance from closing track.

13. An airbag according to claim 1 wherein several chambers are connected to the distribution element.

14. An airbag according to claim 13 wherein the chambers are connected to the distribution element separately from one another.

15. An airbag according to claim 13 wherein a connecting fabric is located between said chambers.

16. An airbag according to claim 13 wherein the distribution element and the chambers are manufactured of materials with different physical characteristics.

17. An airbag according to claim 1 wherein the distribution element is formed from several parts.

18. An airbag according to claim 17 wherein the parts of the distribution element are made of materials with different physical characteristics.

19. An airbag according to claim 1 wherein the connecting tracks extend over the entire length of chamber.

20. An airbag according to claim 1 wherein the distribution element exhibits a material of higher temperature resistance and/or tear-resistance in the area of the acceptance device than in the area of the outflow openings.

21. An airbag according to claim 1 wherein the distribution element is only covered with the bottom section of the chamber which exhibits the outflow openings and the top area of the distribution element projects from the chamber.

22. An airbag according to claim 1 wherein straps are provided on the distribution element for fixing the airbag inside the vehicle.

23. An airbag according to claim 4 wherein the chamber and/ or the hollow body and/ or the membrane are formed from fabric or foil or film material.

24. Process for manufacture of an airbag, in particular an airbag for the head and shoulder area, with a distribution element for gas from a gas generator and with at least one inflatable, multi-layer chamber that can be filled with gas from the gas generator and is connected from the point of view of flow with outflow openings of the distribution element, which exhibits at least one acceptance device for the gas generator and is connected to the airbag, each layer of the chamber is connected to the distribution element via an individual connecting track and the distribution element is closed forming a hollow body.

25. Process according to claim 24, wherein the hollow body is closed via a closing track and the connecting tracks are implemented at a distance from the closing track.

26. Process according to claim 24 wherein the chamber is closed with a circumferential track after formation of the closing track.

27. Process according to claim 26 wherein the closing track, the connecting track and/ or the circumferential track are done by sewing, glueing or welding.

28. Process according to claim 24 wherein a membrane with outflow openings is inserted between the layers of the chamber and a covering panel of the distribution element, which is connected to said layers of the chamber and covering panel.

29. Process according to claim 28 wherein the membrane is glued, welded or sewn.