Land vehicles – Wheeled – Attachment
Reexamination Certificate
2002-12-27
2004-04-27
Dickson, Paul N. (Department: 3616)
Land vehicles
Wheeled
Attachment
C137S069000
Reexamination Certificate
active
06726241
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a cold gas generator for an airbag system comprising a storage device filled with a gas under pressure; a gas outlet opening which in the rest state is pressure-tightly closed by a thin-walled sealing disk; a support device for supporting the sealing disk against the gas pressure acting on it; and a triggering device for affecting the support device, wherein the support device comprises a pressure plate resting against the sealing disk and a support lever supporting the pressure plate as well as the sealing disk.
2. Description of the Related Art
Known cold gas generators have a storage device in which the gas is stored at ambient temperature under high pressure for filling an airbag, when needed. In the rest state, a gas outlet opening is closed in a gas-tight way so that the gas pressure is maintained over the service life of the cold gas generator. A control device which is activated in case of an accident produces a signal which actuates the triggering device for opening the gas outlet opening. The gas stored in the storage device can then flow through the gas outlet opening and a correlated supply path into the folded airbag. The airbag is inflated whereby the gas expands to the desired filling pressure because of the correlated volume increase. The desire for a light-weight construction in the automobile industry as well as for improved safety measures with optionally a plurality of airbags and cold gas generators has resulted in the demand that they be constructed smaller and lighter, and have a more reliable function. The small size results in a high storage pressure of the gas in the storage device which leads to complex requirements in particular in the area of the gas outlet opening and the triggering device. On the one hand, the closure of the gas outlet opening must be configured such that it withstands high gas pressure while sealing it permanently gas-tightly even with respect to diffusion processes. Moreover, the triggering mechanism must be configured such that an accidental erroneous triggering is prevented and a controlled triggering with an energy expenditure as little as possible can take place.
In this connection, different configurations are known from German patent application 195 40 61 8 A1 in which the gas outlet opening is closed by a gas-tight film. The gas tight film is sized such that by itself it cannot withstand the pressure force of the filled-in gas. In the rest state, a support device supports the sealing film against the gas pressure acting on it. The support device has a pressure plate resting against the sealing film and also comprises a support element. The pyrotechnical charge acts, when needed, onto the support device such that its support action is eliminated. The gas pressure then destroys the sealing film so that the stored gas can be released in order to fill an airbag.
In the aforementioned prior art reference different configurations of the support device are illustrated in which the support device is a unitary part and is plastically deformed by the pyrotechnical charge such that its support action is eliminated. For supporting the sealing film against high gas pressure the support device must be sized to be correspondingly strong. This has the result that for its plastic deformation a large amount of energy must be provided by the pyrotechnical charge.
In one variant the pressure plate is supported by an elbow lever whose elbow joint is angled and is supported against the pyrotechnical charge. In the triggering situation, the pyrotechnical charge must first stretch the elbow joint against the gas pressure acting on it which requires a high energy expenditure. The permanent support of the elbow joint on the pyrotechnical charge prevents maintenance and inspection work. Minimal mounting tolerances can result in an accidental tearing of the sealing film.
In a further variant, the support plate is configured as a unitary part of the support element. For opening the gas outlet opening, the pyrotechnical charge acts laterally on it wherein the support device carries out a pivot movement. When carrying out this pivot movement, the edge of the pressure plate facing the triggering device must be lifted against the sealing film and the gas pressure acting on it before triggering can occur. This also requires a correspondingly high energy expenditure. The illustrated embodiments are sensitive with regard to tolerances in the area of the support and of the triggering device. Minimal movements can result in an accidental tearing of the sealing film.
SUMMARY OF INVENTION
It is an object of the present invention to provide a cold gas generator with improved reliability and reduced actuation energy.
In accordance with the present invention, this is achieved in that the pressure plate and the support lever are configured separately from one another, in that the support lever is supported in a pivotable way on a bearing so as to receive forces in the pressure direction and to be force-free in a direction transverse thereto, and in that the triggering device acts on the support lever so as to pivot it about the bearing.
It is thus suggested to close the gas outlet opening with a sealing disk in a pressure-tight way and to support the sealing disk in the rest state on a support device which is comprised of a pressure plate resting against the sealing disk and a separately configured support lever. The support lever is supported on the bearing so as to be pivotable and receive forces in the pressure direction while being force-free in a direction transverse thereto. The corresponding triggering mechanism is configured such that in the release situation the support lever pivots about its bearing. With this configuration, the triggering device in the rest state is not loaded by the support device. Mounting tolerances of the triggering device have no effect on the support action of the support device. With the above described bearing and the type of actuation of the support lever, its actuation does not result in a lifting of the pressure plate or of the sealing disk counter to the gas pressure acting thereon. For the actuation to take place, only a minimal energy level for overcoming the occurring frictional forces is required. As a result, the triggering device can be small which, in addition to weight and space savings, also results in a reduction of the released amount of pollutants, particularly in the case of employing a pyrotechnical charge.
The pivotable end of the support lever has advantageously a rounded portion whose radius matches in particular approximately the spacing of the pivotable end from the bearing. In this way, the support lever can carry out a certain pivot stroke which leaves the support action unchanged. This enables generous positional tolerances for the support lever without impairing its support action; this contributes to the prevention of accidental erroneous triggering. Advantageously, a corresponding rounded recess is provided on the pressure plate and is engaged by the rounded pivotable end of the support lever. This provides a safe guiding and mutual adjustment.
A static gas pressure acts on a closed opening perpendicularly to its opening plane. A center axis of the opening extending perpendicularly to the opening plane and positioned at the center of gravity of the surface area of the opening therefore also defines the position and alignment of the resultant pressure force. By arranging the bearing on the center axis of the opening of the gas outlet opening, the resultant pressure force is oriented toward the bearing so that unsymmetrical loading of the support device is prevented; this contributes to a reduction of the triggering energy. Another contribution to the reduction of triggering energy is made by the configuration of the bearing of the support lever as a shaft journal by which the resultant frictional forces and, as a result of this, the required actuation energy can be kept minimal.
In an expedient configuration the pressure p
Dickson Paul N.
Dunn David R.
Huckett Gudrun E.
Welz Industrie-produkte GmbH
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