Land vehicles – Wheeled – Attachment
Reexamination Certificate
2002-02-20
2004-03-16
Dunn, David R. (Department: 3616)
Land vehicles
Wheeled
Attachment
C280S735000
Reexamination Certificate
active
06705642
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for deflating a gas bag, in particular for deflating an airbag in an active passenger safety system in a vehicle.
BACKGROUND OF THE INVENTION
In order to reduce the risk of injury to passengers in a vehicle in the event of a traffic accident, modern vehicles are increasingly equipped with an active passenger safety system. An active passenger safety system of this kind generally comprises one or more airbags, which are inflated extremely quickly in the event of an impact of the vehicle, and which absorb the energy released by the passenger on impact.
The airbag, for example a frontal airbag, is released from the dashboard respectively the impact cup of the steering wheel at a very high velocity (200 to 300 km per hour). In order to avoid injuries to the passenger caused by the release of the airbag it is therefore advantageous to interrupt or control the complete inflation or unfolding of the airbag, as soon as the passenger has plunged sufficiently far into the airbag and an adequate pressure has built up in the airbag to absorb the energy of the passenger safely. Because the time at which the passenger has plunged sufficiently far into the airbag depends very strongly on the seating position of the passenger at the time of the accident, the interruption of the inflation procedure of the airbag may become necessary at any stage of its release.
Since an inflation device which functions on the basis of pyrotechnology, a so-called inflator, cannot, as a result of the system, be interrupted at any desired time in its function, a passenger safety system must consequently comprise a device for targeted deflation of said airbag in order to control the interruption of the release procedure of the airbag. A device of this kind must allow the gas introduced by the inflator into the airbag to be released at any desired time in order to prevent the continued inflation of the airbag.
A device is known from WO-A-98/01323, in which the gas bag comprises a deflation opening, which is closed at a predetermined breaking line. The breaking line is designed in such a manner that it remains intact below a predetermined target pressure within the airbag, and automatically breaks open under the influence of said pressure above the target pressure. A predetermined breaking line of this type is generally achieved through a careful, technically accurately dimensioned weakening of the material used. Such a weakening of the material can be achieved e.g. by a perforation, in which small incisions are made along the predetermined breaking line. In another embodiment, the predetermined breaking line is produced when closing said airbag by means of a seam produced by stitching, whereby the thread used for stitching and the spacing between stitches is adapted accurately to the requirements for the release of the airbag. Alternatively, the airbag skin may also be sealed by welding, e.g. by ultrasound welding, with exactly adapted welding patterns. In this case, the welding seam is the predetermined breaking line.
The problem with predetermined breaking lines of this kind, which break open automatically under the pressure from the airbag, is that, as a result of manufacturing tolerances, it is extremely difficult to accurately adjust the required target pressure at which the predetermined breaking line breaks open.
SUMMARY OF THE INVENTION
The object of the present invention is consequently to propose another device for the targeted deflation of a gas bag.
According to the present invention, this object is achieved with a device for deflating a gas bag, in particular an airbag, wherein said gas bag comprises at least one deflation opening, which is sealed at a breakable, predetermined breaking line, and wherein said predetermined breaking line comprises a closure element, which can be broken open by allowing said closure element to melt or sublime.
By contrast with the previously known devices, the device according to the present invention is released actively by the melting or burning of the closure element, and the predetermined breaking line is broken open. This means that the breaking open of the predetermined breaking line can be controlled accurately at any given time. The deflation device can, for example, be released by an airbag control module, after a sensor device has detected an inflation volume of the airbag adequate for the absorption of the energy released.
A further advantage of the device according to the invention is in the separation of the release function (melting or burning said closure element) and the breaking open function of the predetermined breaking line. Accordingly, the predetermined breaking line can be optimized to break open rapidly without expenditure of force and without impairing too extensively the mechanical strength of the predetermined breaking line in the closed condition of the deflation opening. In fact, on the one hand, the predetermined breaking line must break open easily and without the expenditure of force when the device is released, in order to release the deflation opening of the airbag within the shortest possible time. On the other hand, the folded airbag must be safely sealed in order to guarantee inflation in the event of an impact. Especially during production of the airbag and installation into the vehicle, the airbag must withstand deformations and loading arising in this context, without suffering damage which could reduce its proper function throughout its required operating life. The separation of the various functions in the device according to the invention allows these contradictory demands on the system to be met.
In a first advantageous embodiment, the predetermined breaking line comprises a closure seam produced through an appropriate manufacturing technique in the material of the gas bag, and the closure element comprises a seam fiber determined by the manufacturing technique and made from the material the gas bag. With this embodiment, an electrical element, especially an electrically conductive heating fiber is associated with the seam fiber, which heats the seam fiber at at least one position up to a temperature above the melting temperature of the material of the gas bag when an electrical current is passed through it. As soon as the seam fiber is broken through at at least one position, the closure seam can, if designed appropriately using special weaving respectively knitting techniques, be opened without the expenditure of force, thereby releasing the deflation opening.
In a second advantageous embodiment, the predetermined breaking line comprises a closure seam, and the closure element comprises a seam fiber made from electrically conductive material. The melting or sublimation of the closure element can, in this embodiment, be achieved directly by passing an electrical current through the closure element.
In a further advantageous embodiment, the predetermined breaking line comprises a first and second row of closure members, wherein the closure members of the first row are arranged at a first edge of the deflation opening of the gas bag, and the closure members of the second row are arranged in such a manner at a second edge of the deflation opening of the gas bag that the closure members of the first row and the closure members of the second row are offset in the direction of the predetermined breaking line, and wherein the closure members of the first row and the closure members of the second row interlock to form a keyed closure in the sealed condition of the gas bag, as is realized, for example, in the case of a zip fastener. The predetermined breaking line can, for example, be designed as a slide-less zip fastener, i.e. as a zip fastener in which the closure element for producing the keyed closure, the so-called slide or glide, is removed, wherein the zip fastener is worked into the deflation opening of the gas bag. In this case, the closure element preferably comprises an electrically conductive fiber, which holds together the first and second row of closure memb
Hauer Ernst Johann
Meyer Michael
Petri Volker
Rudolf Harald
Serban Bogdan
Dunn David R.
I.E.E. International Electronics & Engineering S.a r.l.
McCormick Paulding & Huber LLP
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