METHOD OF MANUFACTURING AN AIRBAG MINI-PACK

Abstract

A method of manufacturing a folded airbag comprising the steps of: providing an airbag cushion; heating the airbag material, folding the heated airbag material; compressing the folded airbag material obtained in step c) and optionally cooling the compressed airbag.

Claims

1. A method of manufacturing a folded airbag comprising the steps of: a) providing an airbag cushion; b) heating the airbag material, c) folding the heated airbag material; and d) compressing the folded airbag material obtained in step c).

2. The method according to claim 1, wherein the heating of the airbag cushion is continued during the folding step, preferably up to the completion of the folding.

3. The method according to claim 1, wherein the heating is carried out at a temperature comprised within the range from +50 C. to 150 C.

4. The method according to claim 1, wherein the heating is carried out by at least one heating element selected from heat mats, heating foils, infrared sources or other heating devices.

5. The method according to claim 4, wherein the at least one heating element is selected form heating foils and IR sources.

6. The method of claim 5, wherein beams of the IR source are perpendicular to the airbag material.

7. The method according to claim 1, wherein the airbag cushion is made of a fabric material.

8. A system for packaging an airbag cushion comprising an airbag cushion, a folding device, a compressing device, and at least one heating element provided upstream said folding device.

9. The system for packing an airbag cushion according to claim 8, wherein the at least one heating element is selected from heating mats, heating foils, infrared sources and other heating devices.

10. The system of claim 8, wherein the airbag cushion is straightened by appropriate fastening means.

11. An apparatus for packaging an airbag cushion in a pack comprising a folding device, at least one heating element suitable to heat an airbag cushion, and a compressing device.

12. The apparatus for packaging an airbag cushion according to claim 11, wherein the heating element is provided at a location that is different from the location of the folding device for the airbag cushion.

13. The apparatus according to claim 11, wherein the heating element is selected from heating foils, infrared sources or combination thereof.

14. The apparatus according to claim 11, further comprising a cooling device suitable to cool a folded airbag cushion.

15. The system for packing an airbag cushion according to claim 8, further comprises a cooling device.

16. The method according to claim 1, further comprises the step of cooling the compressed airbag obtained in step d).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention will now be described in a non-limiting way with reference to the accompanying drawings, in which:

[0041] FIG. 1 is a schematic representation of heating the airbag cushion according to a first embodiment of the method of the present invention;

[0042] FIG. 1a is an alternate embodiment of the invention.

[0043] FIG. 2 is a schematic representation of heating the airbag cushion according to another embodiment of the method of the present invention;

[0044] FIG. 3 is a schematic representation of an apparatus according to the invention; and

[0045] FIG. 4 shows another view of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0046] Referring initially to FIG. 3, an apparatus 7 for folding air bag cushions 1 comprises a device 8 that can transfer heat to a cushion 1 to an extent sufficient to heat the cushion material. The material of the cushion is preferably a thermoplastic material, so that once heated it can become softer, i.e. more pliable, than when it is cold, e.g. at room temperature; the cushion may be made of a fabric, the fabric may be coated in a way known in the art. The invention provides for the cushion to be heated at least before it is folded, rather than after the folding step. The heated cushion 1 is then folded in a folding device 9, in a way known per se in the art; the folded airbag cushion is compressed in device 10, in a way known per se in the art and optionally cooled in cooling device 11.

[0047] FIG. 1 schematically shows the first embodiment of the method and system of the present invention, wherein an IR source 4 is used for heating or warming up the airbag cushion 1 to a specified temperature to change its material characteristics to sufficiently soft but not melted or tacky and with reduced stiffness. The airbag cushion 1 is straightened by fastening a first portion of the airbag to fastening means, such as a folding clamp 2 and by introducing a second portion thereof into a folding device 9 (not shown in FIG. 1). The airbag cushion 1 is heated at least before the folding step; in one embodiment the cushion may be heated also during the folding step. The IR source 4 is placed at a distance that allows projecting a sufficiently intense IR beam 4a to warm the airbag fabric material and the layers of cushion 1 to a temperature specified in function of the features of the material of the airbag fabric. As stated above, the heating time is a function of the IR intensity, the distance of the IR source from the external surface of the airbag cushion, the airbag material and the thickness of the airbag layers. The skilled person can easily select the values for the above parameters. As can be appreciated only an edge view of the airbag illustrating the height of the airbag is shown in these figures. FIG. 4 shows a plan view of the material 1 with two spaced IR sources 4 as well as the neck or inlet 1a of the airbag. To achieve the desired heat transfer across the entire airbag the airbag can be moved relative to the heating source or the heating source can be moved or the heating source can have sufficient length and depth to enable its radiation to impinge upon the entire airbag without much if any relative movement.

[0048] The folded airbag is compressed in device 10 by applying a predefined load 10a and, finally, the compressed airbag is left to cool or is cooled by appropriate cooling means 11. The obtained compressed and folded airbag is placed into an airbag housing 3 and it stably maintains its small volume.

[0049] FIG. 1a shows an alternate embodiment wherein the IR source is of approximately the same length as the fabric to be heated. In this embodiment the IR source is removed from the folding device 10 requiring the heated airbag to be transported to the folding device.

[0050] FIG. 2 shows another embodiment of the method and system of the present invention, wherein the heating source is a pair of heating foils 5 applied on carrier plates 6 that transmit heat to the airbag material by conduction. One extremity of said carrier plates 6 is inserted in the folding device (not shown) or can be positioned therein automatically when the airbag cushion 1 is straightened or held by clamps 2 in the system for packing the airbag. In the shown embodiment, both sides of the airbag cushion are directly heated by the heating foils 5 to the required temperature and the heated airbag material or layers are moved to the folding device 9 (not shown in FIG. 2). In a possible embodiment, the heating of the airbag cushion is continued during the folding step to further improve the efficiency of folding and compression to minimise the airbag package.

[0051] The method of the invention preferably provides that the heating is carried out at a temperature comprised within the range from +50 C. to 150 C. In a possible embodiment the heating is carried out by at least one heating element selected from heat mats, heating foils, infrared sources or other heating devices; preferred heating means are selected form heating foils and IR sources or a combination thereof. When IR is used, the beams of the IR source are preferably perpendicular to the airbag material.

[0052] The following examples are provided for illustrating the present invention without limiting its scope to these examples.

[0053] Several experiments were conducted in order to provide some examples for the use of IR emitters according to the present invention for heating, i.e. warming up, different types of airbag materials to improve folding of airbag fabric materials and compression of the folded airbag into a pack having very reduced dimensions.

EXAMPLE 1

Heating with IR Emitters

[0054] Some experiments were conducted with a short wave IR emitter manufactured by Optron GmbH, Type IRD S380SM powered by 2 kW. The IR emitter provided a maximum spectral emission of 1.2 gm for the airbag cushion and a heated length of 380 mm (beam apertures were 380 mm).

[0055] Different airbag fabric materials were tested in this experiment, which were coated, uncoated and partially coated. In particular, the tested airbag materials were made of the following yarns: 470 dtex PA66 coated fabric (nylon); 470 dtex PET coated fabric (polyethylene terephthalate); 350 dtex PA66 uncoated fabric and 350 dtex PA66 partially coated fabric.

[0056] The same experiments were repeated with the difference that the short IR emitter of Optron GmH, type IRD S750Z, powered by 6 kW and the heated length of airbag material was 750 mm (beam apertures were 750 mm).

[0057] In the above experiments using said two types of short wave IR emitters, the heating time was comprised within the range from 10 s to 50 s and the temperature on the external surface of the airbag material, which was in contact with the IR beams, was comprised within the range of 90 C.-140 C.

[0058] The heated airbag fabric was folded, compressed and cooled in a known way. The obtained airbag pack had a much reduced dimension with respect to the airbag packs manufactured by the known methods without applying heat or by the known methods wherein heat was applied to the already folded airbags.

EXAMPLE 2

Heating with Heating Foils

[0059] Some experiments were conducted with a pair of commercially available heating foils that allowed to heat up the different types of airbag materials identified in Example 1. A heat foil was applied on two opposed sides of a straightened airbag material and an airbag surface of 120 mm300 mm was heated on each side of the airbag by the heating foils, powered by 65 W at 220 V.

[0060] The results of these experiments confirm the invention is capable of achieving a significantly reduced folded and compressed airbag pack. In addition, the airbag pack obtained by means of the method of the present invention stably retains its compact a reduced dimension.

[0061] In a possible embodiment, the material of the airbag cushion may contain a material that can store heat during the folding step. Said heat storing material may be added as a filler to the cushion material, e.g. in the material that provides the coating to the fabric. Suitable materials are iron silicates, such as copper slag, as disclosed in KR application 10-2001-0058900 (KR2003-0028859) and in US2013/040082; iron silicates may also act as a heating means when irradiated by an electromagnetic field or electromagnetic waves, in particular by microwaves.

[0062] Many changes and modifications in the above-described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, that scope is intended to be limited only by the scope of the appended claims.