Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-03-17
2001-08-14
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Attachment
C280S736000, C280S741000
Reexamination Certificate
active
06273453
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an occupant impact protection system, in particular for a motor vehicle, with an airbag that when triggered is to be inflated from its folded installed condition and furthermore with at least one gas generator, which is to be activated by means of an ignition apparatus and which contains a gas-producing material for producing the quantity of gas required to inflate the airbag.
Such occupant impact protection systems are known in a multiplicity of embodiments and today are installed in great numbers in mass-produced automobiles. During driving operations, when a critical accident situation occurs, sensors arranged appropriately in the vehicle trigger the gas generators, which then inflate the airbags, which are installed at different positions in the vehicle, by introducing therein the gas produced by the gas generators.
With a view especially toward multiple collisions or a vehicle rolling over several times during a prolonged accident period, the occupant impact protection system should have a sufficient service life, especially the airbags, and for this reason in many areas of the vehicle there are solid impact elements made of foamed plastics. Secondly, the inflated airbags should dampen the impact of the occupant on the airbag by intentionally discharging the gas that has been introduced (ventilation). Embodying a hose-like side airbag is known from U.S. Pat. No. 5,322,322; the airbag has an internal rubber bladder and an external airbag material. The known airbag is thus very dense and consequently does have a prolonged service life. However, in the case of head impact, it is so hard that it can only absorb a limited amount of energy and therefore causes the rebound effect, which is to be avoided.
The object of the present invention is therefore to embody an occupant protection system with the aforesaid features such that the protective effect of an inflated airbag is maintained beyond the service life of the gas-inflated airbag.
SUMMARY OF THE INVENTION
This object is achieved, including advantageous embodiments and further developments of the invention, from the contents of the patent claims that follow this specification.
The basic idea of the invention is that the airbag is foamable in at least part of its volume by means of particles introduced therein that are made of plastic or polymeric material that foam when activated and that are activated together with the introduction of the gas produced by the gas generator and a solid structure is formed for impact protection after the plastic foam hardens.
Known from DE-U-297 03 360 is providing a sealant in a liquid or solid form in a separate container, which sealant is absorbed by the gases produced upon ignition and is transported into the inflating airbag so that the sealant seals the interior surfaces of the inflated airbag and enhances its service life. A sustained improvement in the protective effect of the airbag is not associated therewith, in particular when the airbag is vented when there is an impact.
Furthermore known from DE 295 16 703 A1 and DE 196 24 328 A1 is arranging inflatable bodies on the exterior of a vehicle for damping the impact energy, which bodies are also to be filled with a foam.
Only the present invention is associated with the advantage that, in addition to the protective function of a gas-filled airbag in the interior of a vehicle, due to its partial foaming, the airbag has permanent stability under load, even after the gas introduced has been discharged (vented), and thus the elasticity of the plastic foam that has been introduced is available for further energy absorption so that it offers effective protection, in particular in multiple collisions.
In accordance with one exemplary embodiment of the invention, it is provided that the plastic particles are stored in the airbag and are activatable by means of the in-flowing gas, whereby preferably the plastic particles stored in the airbag form an internal coating on the airbag material that upon activation of the plastic particles constitute a solid foam structure that is separate from the airbag material. In this embodiment of the invention it can be provided that the gas produced by the gas generator contains an activating reagent for the plastic particles stored in the airbag.
An alternative option is for the plastic particles to be stored in the gas generator and to be taken up or absorbed by the gas flow produced in the gas generator and introduced into the airbag and activated for foaming therein. The plastic particles can be stored in liquid form or in solid form in the gas generator.
Such storage of the plastic particles in the gas generator is associated with the advantage that the stored plastic particles are activated in the airbag and they absorb energy, first from the heat that occurs from burning off the gas-producing material and second from the pressure of the gas flowing out of the pressure chamber so that a foam forms in the airbag that hardens after a short period of time and constitutes a permanent solid structure. Thus, even after the gas has been vented out of the airbag, a shape-stable protective body remains that continues to offer good and sufficient protection for the vehicle occupant during multiple impact or if the vehicle rolls over.
The plastic particles are to be selected and designed such that the plastic particles stored in the gas generator are small and light so that there are no rattling noises in the moving vehicle in the gas generator that has not yet been triggered. Furthermore, the plastic particles must be dimensioned such that they can flow through any discharge openings, even those provided with filter elements. In addition, during the discharge process, the particles must not be accelerated such that they damage the material of the airbag when they impact thereupon, thus bursting the airbag. Furthermore, when the plastic particles are activated, no smoke should occur that flows via any ventilation devices into the interior of the vehicle, and finally, the plastic particles must be of a quality that ensures a reliable foaming process both at very low and at very high temperatures.
In accordance with one exemplary embodiment of the invention, it can first be provided that the stored plastic particles are disposed in the gas generator together with the gas-producing material. Alternatively, a separate pressure chamber for storing the plastic particles cam be provided in the gas generator.
In accordance with one exemplary embodiment of the invention, it is provided that, in addition to the chamber containing the gas-producing material and the pressure chamber for receiving the plastic particles, the invention has a mixing chamber, whereby the discharge openings leading to the airbag are associated with the mixing chamber.
In a first exemplary embodiment the plastic particles present as granules and stored in the allocated chamber of the gas generator are stored in an inert gas atmosphere that is under pressure, whereby the particles preferably comprise polypropylene. When such a plastic is employed, a principle of the extrusion/injection process is used that is known in plastics engineering.
In an alternative embodiment the pressure chamber for receiving at least two components of a thermosetting plastic is set up in an inert gas atmosphere that is under pressure, whereby a polyurethane can be employed as such a thermosetting plastic, so that in this case the principle of a Duromer casting process is used, which is known in plastics engineering.
If the plastic particles are stored in an inert gas atmosphere that is under pressure, the inert gas used can be, for example, argon.
In accordance with one exemplary embodiment of the invention, the discharge openings are provided with filter elements that permit the plastic particles to flow through them.
With regard to the design of the airbag, in accordance with one exemplary embodiment the airbag is a single-chamber airbag, whereby the airbag filled with gas first provides the occupant lateral
Juchem Alois
Rau Sven
Satzger Guido
Tiefenthaler Peter
Autoliv Development AB
Divine David
Robert W. Becker & Associates
Swann J. J.
LandOfFree
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