Inflatable air-bag and method formanufacturing the same

SWEDEN (12) PATENTS US) C2 (11) 523 328

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(19) SE (51)

International class ⁷

B60R 21/16, 21/24

PATENT AND REGISTRATION (45) (41) (22) (24) (62) (86) (86) (83)

Patent granted 2004-04 '

Application widely available 2002-08 The patent application was filed 2001-02

Running day 2001-02

Tribal application number

International filing date Filing date for European patent application Deposit of microorganism (21)

<td colspan="2"> 13</td><td>number 0100352 4</td>

<td colspan="3"> 07</td>

<td> 06</td><td colspan="2">Application received as:</td>

<td colspan="3"> 06</td>

<td></td><td>X</td><td>Swedish patent application</td>

<td></td><td></td><td>completed international patent application</td>

<td></td><td></td><td>with number</td>

<td colspan="2"> □</td><td>converted European patent application with number</td>

(30) Priority information (73) (72) (74) (54) (56) (57)

PATENT HOLDER FOV Fabrics AB, Box 165 503 08 Borås SE

INVENTOR Mats Johansson, Aplared SE

OMBUD AWAPATENT AB

NAME Inflatable air bag and method of manufacture

CALLED PUBLICATIONS:

EP A2 1 044 803 (B32B 27/12), US A 5 653 464 (280 / 743.1), US A 5 480 181 (280 / 730.2)

SUMMARY:

The invention relates to an inflatable air bag (5) for vehicles. The air bag (5) comprises at least one seam (1) through which the fabric layers (2) in the air bag (5) are connected, as well as a gas-tight bag. Said bag comprises two gas-tight layers (3) joined together, the gas-tight layers (3) being joined at a portion between the seam (1) and the middle of the air bag (5) to form an airtight volume within the seam (1).

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The numbers in brackets indicate international identification code, INID code. Letters in clamps indicate international document code.

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SUMMARY

The invention relates to an inflatable air bag (5) for vehicles. The air bag (5) comprises at least one seam (1) through which the fabric layers (2) in the air bag (5) are connected, as well as a gas-tight bag. Said bag comprises two gas-tight layers (3) joined together, the gas-tight layers (3) being joined at a portion between the seam (1) and the middle of the air bag (5) to form an airtight volume within the seam (1).

Publication figure: 1

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Technical area

The present invention relates to an inflatable air bag for vehicles, the air bag comprising at least one seam through which the fabric layers in the air bag are connected.

Technical background

Inflatable air bags or airbags are now generally standard in all new cars. This is particularly the case with airbags designed to protect in the event of a frontal collision. However, safety requirements have increased and this has resulted in collision protection which protects in side collisions, side curtains, and when cars turn around, so-called role over-protection.

In all types of collisions, it is important that the air bag is filled quickly. In the event of a frontal collision, it is also important that the air pressure that is quickly built up also decreases quickly after the collision in order to as softly as possible capture the driver or passengers and for them to be able to move and get out of the vehicle after the collision. This type of airbags has usually been sewn by fabrics or woven in one piece, jacquard fabric, which fabric has in many cases been coated on the inside or outside with, for example, silicone to reduce gas flow.

On the contrary, for side curtains and roll-over protection, it is important that an overpressure can be maintained in the inflatable air bag for as long as possible, preferably more than five seconds in that the time it takes for a car to turn around is often longer than the time. for a frontal collision. One of the known techniques for coping with holding the overpressure for an extended period of time in an inflatable air bag, in addition to the fully woven air bag with

523 328 silicone-clad inside or outside, consists of silicone-coated fabric layers being joined to an inflatable air bag with the coated side facing inward. To prevent air from leaking at the seams, the two layers of fabric are joined together with glue along the seams and on both sides of the seams. In this way, it is the adhesive joints that are loaded when inflating the air bag and not the seams. An example of this is described in DE 19852232-A1 where the glue joint also covers the seams on the outside of the inflatable air bag.

GB 2343868-A describes a similar solution where glue joints are combined with seams.

Coating fabrics with silicone or any other material is time-consuming and very costly. Adhesion of two silicone coated fabric layers is also difficult as few materials adhere to a silicone coated surface. Ironing the glue at the seams is also an extra work step that requires high precision. In these cases, the pouring time for the overpressure in an air bag is often at the minimum required.

Summary of the Invention

The object of the present invention is therefore to provide an inflatable air bag which is capable of sustaining an overpressure during inflation for a longer period of time, and a method of manufacturing such an inflatable air bag.

The object has now been achieved by the invention by means of an inflatable air bag having the features set forth in the following claim 1 with preferred embodiments in the following claims 2 and 3.

The inflatable air bag according to the invention thus utilizes a gas-tight bag which lies inside the sewn bag of fabric. In the traditional solutions and in the present invention there is a great burden on the seams. In the present invention, the seam has no sealing function, which means that it is not critical for air bag tightness if the load is large on the seams. Also, the fabric does not need to be coated with silicone or the like to keep the air bag tight. The need

ΟΖό όΖ8 of bonding is eliminated as the dense portion of the air sac is a bag. The gas-tight bag is preferably made of two joined gas-tight layers. The gas-tight layers are preferably fixed in their planes relative to the layers of fabric. Also important for the invention is that the gas-tight layers are joined at a distance from the seam that holds all the layers together. The advantage of this is that the load becomes focused on the seam with no impact on the tightness. The gas-tight layers are preferably welded together, which has the advantage that no extra material needs to be added.

The invention is also based on the idea that an inflatable air bag is made by sealing a gas-tight bag between two layers of fabric. The advantages of this procedure are the fabric does not need to be laminated to become gas tight which means that the fabrication becomes both simpler and cheaper.

In a second method, two gas-tight layers are sewn in between the fabric layers instead. The advantage of this procedure is that a finished bag of a certain shape does not need to be produced in advance and fitted. Preferably, the gas-tight layers are joined together at the same time as all the constituent layers of the inflatable air bag are sewn together. The advantage is that everything is done in one step. In an alternative process, the gas-tight layers are joined together in a work step after the ingoing layers are stitched together. Preferably, the gas-tight layers are welded together. This can be done with, for example, heat, laser or high frequency welding. The heat is adjusted so that it does not affect the surrounding tissue in the inflatable air bag, ie. it is high enough to fuse the gas-tight layers but not high enough to affect the weave layers.

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Brief description of the figures

The invention will henceforth be further described by an exemplary embodiment with reference to the accompanying figures.

Figure 1 shows a cross-section of the seam and layers in a preferred embodiment of an inflatable air bag according to the present invention.

Figure 2 shows a cross section of an inflated air bag.

Description of preferred embodiment

Figure 1 shows a section of a cross-section of the inflatable air bag 5. Two fabric layers 2 and two gas-tight layers 3 are sewn together with a seam 1. The gas-tight layers can, for example, be any polymer that is heat-resistant when high heat develops when inflating the air bag. 5. The gas-tight layers are joined by a weld 4 at a small distance from the seam 1. For example, the welding could be done with a presser foot which is provided with a heating element which welds together the gas-tight layers 3 at a distance from the seam 1 while all layers 2, 3 are sewn together. Preferably, however, the jointing takes place with high frequency welding.

A multi-channel inflated air bag 5 is shown in cross-section in Figure 2. The figure illustrates that the density is not affected by strain on the seams 1 which is one of the main ideas of the invention. As the gas-tight layer expands upon inflation due to pressure and / or heat, the seams will eventually be loaded. With the present invention, it is of no importance for the tightness of the air bag 5 that the seams are loaded as the weld 4 is separate from the seam. Alternatively, the seam 1 and the weld 4 may be arranged in such a way that the weld 4 covers the seam 1, which means that the seam 1 is not loaded when inflating the air bag. However, this requires that the weld 4 is sufficiently wide on the inside of the seam 1 to be able to absorb the load.

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It will be appreciated that a variety of modifications to the above-described embodiment of the invention are possible within the scope of the invention, as defined by the appended claims. For example, as described, the gas-tight layers 3 can be welded together before being placed between the fabric layers 2 to be sewn together. A further alternative may be to attach the gas-tight layers 3 to the fabric layers 2 before the gas-tight layers are welded together and before all layers are sewn together. This can be done as a laminate but where the adhesion of the gas-tight layers 3 to the fabric layers 2 is weaker than the weld 4 of the gas-tight layers 3.

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