SAFETY DEVICE FOR AN AIRBAG-SYSTEM

Abstract: A safety device for an airbag-system which has not been triggered during an accident, comprising a fabric which is suitable for surrounding a steering wheel of a motorcar which is provided with the airbag-system. The fabric is suitable for tightening at the side of the steering column on which the steering wheel is mounted, such that if the airbag-system is activated during a rescue operation, inflation of the airbag is hindered by the fabric.

Description: Safety device for an airbag-system The present invention relates to a safety device for an airbag-system. It is known from the Dutch newspaper De Volkskrant of October 3 1995, that a good 25 years ago already an airbag was designed which would instantly pop out from the middle of the steering wheel of a motorcar the moment sen¬ sors in the motorcar perceive a collision. Such airbags prevent serious injuries to occupants of the motorcar, especially if they were not wearing a safety belt at the time of the collision. Actually, airbags are still subject to constant development, taking better into account the kind of collision and the situation in which the occupants of the motorcar find themselves at the moment of the collision and inflation of the airbag. Practical experience has shown, however, that after an accident or collision one may face the problem that the airbag is not yet activated and assistance to the occu¬ pants takes place while the risk exists that the airbag will still inflate. This is a danger for both the helpers and occupants needing assistance. It is the aim of the invention to avoid this prob¬ lem. According to the invention this is achieved by providing the safety device with a fabric which is suit¬ able for surrounding a steering wheel of a motorcar provided with the airbag-system, and the fabric being suitable to be tightened at the side of the steering column on which the steering wheel is mounted, such that when the airbag-system is activated, inflation of the air¬ bag is hindered by the fabric. Surprisingly this measure proved to provide very effective protection against untimely activation of the airbags, so that neither helpers nor occupants of a car in a crash run the risk of contracting the consequential injuries. When laid out, the fabric is preferably round. This allows the fabric to be fitted around the steering wheel of the motorcar and to fit the fabric tightly around the steering column at the side of the steering wheel where it is directed toward the steering column. The reliable action of the safety device is particularly enhanced by providing the outer edge of the fabric with a cord or ribbon for gathering the outer edge. The fabric can be secured particularly effectively around the steering wheel if the cord or the ribbon is connected at a first extremity with the outer edge of the fabric and is provided at a second extremity with a hook means for the detachable connection of the second extremity to a permanent point. The chosen hook means may, for instance, be a securable carabine hook such as the clog screwgate kind, which has a tensile strength of about 2400 kg. To allow the safety device to function properly, it is desirable that a space of 10 to 15 cm is left between the steering wheel and the fabric fitted around it. In the case of untimely inflation this leaves the airbag suffi¬ cient space for a controlled pressure build-up which, due to the fitted fabric actually mounts up more than without such a fitted fabric. In a first embodiment of the safety device according to the invention at least part of the fabric takes the form of a meshed net . The dimensions of the net may vary. However about 9 x 9 cm has been shown to be a preferred mesh size. This provides the airbag with enough space to allow it to still extend somewhat through the mesh of the net, so that tensions of too great a force in the cords of the net are avoided. The net can be made sufficiently strong by using aramide cords having a diameter of about 7 to 8 mm. Of course, other cords providing sufficient tensile strength are also possible, but especially the use of aramide pro¬ vides a lightweight, yet strong product which is quite suited for the intended safety function. Moreover, this function is maintained over an extensive temperature range. In another embodiment of the safety device according to the invention at least part of the fabric is closely woven and is provided with one or more openings near the outer edge. In general, using a closely woven fabric affords the advantage of halving the sound pressure produced by an activated airbag. The sound pressure of an exploding airbag ranges from 120-150 dB. In addition, very adequate protection is provided against dust production caused by the exploding airbag, which would otherwise cause irritation of the eyes. One may choose, for instance, to make the fabric from the fire-resistant Νomex III ® material made by Ten Cate Protect B.V., Νijverdal, or from metal. Further, when using a fabric, it is desirable to reinforce the openings which serve to limit the pressure build-up when the airbag is activated, by means of, preferably metal rings. A very favourable embodiment is characterized in that at least part of the fabric is formed from closely woven aramide fibres such as, for instance, Kevlar ® . Apart from the above-mentioned advan¬ tages for using aramide there is the further advantage that the fabric - though closely woven - is gas-permeable, affording better control of the pressure build-up from the airbag. The invention will now be further elucidated with reference to the drawing in which Fig. 1 shows a first embodiment of the safety device according to the invention in the spread out state; Fig. 2 shows the safety device in the first embodiment according to the invention fitted around a steering wheel of a motorcar before inflation of the airbag; Fig. 3 shows the safety device in the first embodi- ment according to the invention fitted around a steering wheel of a motor car after inflation of the airbag; Fig. 4 shows the safety device in a second embodi¬ ment according to the invention in the spread out state; and Fig. 5 shows the safety device in a third embodiment according to the invention in the spread out state. Corresponding parts are indicated by the same ref¬ erence numbers. Fig. 1 shows a safety device according to the invention comprising a net 1 provided with mesh 2. The shape of the net 1 is round and its outer edge is provided with a cord 3 which preferably is attached at one extremity 4 to the net 1, and is provided at the other extremity 5 with a hook means 6 for the detachable connection of this second extremity 5 to a permanent point. As shown in Fig. 2, the net 1 is fitted over the steering wheel 7 and tightened at the side of the steering column 8 by drawing tight the cord 3 which, in order to secure the net 1 around the steering wheel 7, may be wrapped several times around the steering column 8 and be fastened by means of the hook 6 into one of the loops 9 or a mesh 2 of the net 1. Fig. 3 shows the situation where the airbag 10 has been activated and the net 1 envelopes the airbag 10, while the airbag 10 can be seen to form bulges 11 through the mesh 2 of the net 1. In this situation, the space between the net 1 and the steering wheel 7 is maximally 10 to 15 cm. Making the net 1 from aramide cords having a diameter of about 7 to 8 mm, provides a reliable safety device which can also be used under fire-hazardous condi¬ tions due to the fact that aramide retains its tensile strength over a wide temperature range. The hook means 6 is preferably a securable carabine hook of the clog screwgate kind, which has a tensile strength of about 2400 kg. Fig. 4 shows a second embodiment of the safety device according to the invention, in which the fabric in its totality is closely woven and is provided with openings 15 near the outer edge. This closely woven fabric can thus be fitted over the steering wheel like a sack. The fabric may be made from fire-resistant Νomex III ® material or possibly from metal. With Νomex III ® or other fabric the openings 15 are preferably to be provided with metal rings for reenforcement . By employing openings 15, the pressure build-up on activation of the airbag is con¬ trolled and does not reach such high values as when such openings are not employed. The closely woven fabric 12 may also be made from aramide fibres, for instance from Kevlar ® . This has the advantage that the openings 15, though useful, are less crucial, because such an aramide fabric is gas-permeable. Fig. 5 shows a third embodiment of the safety device according to the invention, namely a combination of the embodiments shown in Fig. 1 and Fig. 4. In this embodiment part 14, which will be positioned over the steering wheel, is executed as closely woven fabric in order to retain the best possible protection against dust for the benefit of both the occupants of the motorcar and the helpers, which protection is optimal in the embodiment according to Fig. 4. The part 13 surrounding the closely woven part 14 of the fabric takes the shape of a net as shown in the embodiment of Fig. 1. Thus, in addition to the good protection against dust, this embodiment offers very adequate control of the pressure build-up.

Claims: CLAIMS 1. A safety device for an airbag-system, character¬ ized in that the safety device is provided with a fabric which is suitable for surrounding a steering wheel of a motorcar provided with the airbag-system, and which fabric is suitable to be tightened at the side of the steering column on which the steering wheel is mounted, such that when the airbag-system is activated, inflation of the air¬ bag is hindered by the f bric. 2. A safety device according to claim 1, character- ized in that in the spread out state the fabric is round. 3. A safety device according to claim 1 or 2, char¬ acterized in that the outer edge of the fabric is provided with a cord or ribbon for gathering the outer edge of the fabric. 4. A safety device according to any one of claims 1-3, characterized in that a first extremity of the cord or the ribbon is connected with the outer edge of the fabric and is provided at a second extremity with a hook means for the detachable connection of the second extremity to a permanent point. 5. A safety device according to any one of the pre¬ ceding claims, characterized in that a space of 10 to 15 cm is left between the steering wheel and the fabric fitted around it. 6. A safety device according to any one of the pre¬ ceding claims, characterized in that at least part of the fabric takes the form of a meshed net. 7. A safety device according to claim 6, character¬ ized in that the mesh size is about 9 x 9 cm. 8. A safety device according to claim 6 or 7, char¬ acterized in that the net is made from aramide cords having a diameter of about 7-8 mm. 9. A safety device according to any one of claims 1-6, characterized in that at least part of the fabric is closely woven and near the outer edge is provided with one or more openings which are preferably reinforced by means of metal rings. 10. A safety device according to any one of claims 1-6 or 9, characterized in that at least part of the fabric is made from closely woven aramide fibres.

Inventors: MOUWS RAYMOND JOHANNES ADRIANU, MOUWS, RAYMOND, JOHANNES, ADRIANUS
Applicants: MOUWS RAYMOND JOHANNES ADRIANU, SPECAMON B V, MOUWS, RAYMOND, JOHANNES, ADRIANUS, SPECAMON B.V.
Application year: 1996
Main classification: B60R21
IPC codes: B60R21