Ammunition and explosives – Jacketed or cartridge gas generator
Reexamination Certificate
1999-06-30
2001-03-27
Carone, Michael J. (Department: 3641)
Ammunition and explosives
Jacketed or cartridge gas generator
C102S531000, C280S737000, C280S740000, C280S741000, C280S742000, C280S735000
Reexamination Certificate
active
06205928
ABSTRACT:
The invention relates to a gas generator, comprising a first gas-generating stage and at least one gas-generating stage arranged downstream thereof.
BACKGROUND OF THE INVENTION
A two-stage gas generator can be seen in the European Patent Application EP-A2 0 502 630. This describes a hybrid gas generator in which after the mechanical opening of a rupture membrane, cold gas flows out from a compressed gas chamber. The first gas-generating stage is therefore a cold gas stage. As a second gas-generating stage, a propellant charge is provided, which is automatically activated by the change in pressure inside the gas generator. This activation takes place by means of a percussion igniter arrangement connected with a reference pressure chamber.
A disadvantage of the arrangement according to EP-A2 0 502 630 is that this arrangement must compulsorily operate at a reference pressure, which corresponds approximately to the pressure in the compressed gas chamber. A simple adaptation of the generated gas volume is not possible by simple means, in particular not by reducing the pressure inside the gas generator without adapting the reference pressure. The mechanical ignition arrangement provided for the second gas-generating stage is extremely costly, requires several movable parts and the arrangement of striker and percussion igniter, in particular when filling the gas generator, represents a considerable safety risk, because an accidental activation of the percussion igniter can not be absolutely ruled out.
It is an object of the invention to provide a gas generator which makes possible an activation of the second gas-generating stage as a function of a pressure change in the gas generator, however independently of the extent of the pressure inside the gas generator.
SUMMARY OF THE INVENTION
The invention provides a gas generator, comprising a first gas-generating stage and at least one gas-generating stage arranged downstream of the first stage, and also comprising a device for detecting a pressure change in the gas generator, wherein the device for detecting the pressure change comprises a chamber divided by a movable part into two partial chambers which are gas-tight with respect to each other, the partial chambers having openings which are in flow connection with the first stage and each have different cross-sectional areas, so that the pressure change spreads at different speeds in the two partial chambers and brings about a movement of the movable part, and the movable part being connected with a movement meter, which due to the movement of the movable part generates an electrical impulse to activate the second stage.
The basic idea of the invention is to carry out a dynamic pressure comparison instead of the static pressure comparison according to EP 0 502 630 A2, i.e. to detect a chronological change of the pressure. For this, a chamber is provided for measuring the chronological pressure change, which is divided by a movable part into two partial chambers which are gas-tight with respect to each other. Openings in flow connection respectively with the first stage are provided for the two partial chambers, the cross-sectional area of the openings being different. Thereby, a pressure change brought about by the activation of the first stage can spread at different speeds in the two partial chambers. The pressure change can be both a drop in pressure, such as for example with a first cold-gas-generating stage, or a pressure rise, such as for example with the deflagration of a first combustion-gas-generating stage.
A movement meter is connected with the movable part between the air-tight partial chambers, which meter, owing to the movement of the movable part caused by the pressure change, generates an electrical impulse which activates the second stage. e.g. an electric, ignitable propellant charge. The electrically ignitable propellant charge can in turn ignite further propellant.
A particularly preferred further development of the invention is to be seen in that a piezo-element is used as movement meter, which converts the movement or the force onto the movable part by means of the piezoelectric effect directly into an electric impulse, which is sufficiently great to activate an electrically ignitable propellant charge. For the automatic activation of the second gas-generating stage, therefore no additional electrical connection cables or other elements have to be introduced into the interior of the gas generator. The risk of penetration of air and moisture can therefore be avoided. An adaptation of the gas generator output to customers wishes is possible without costly changes to the construction.
REFERENCES:
patent: 5604338 (1997-02-01), Paxton et al.
patent: 5670718 (1997-09-01), Nagahara
patent: 5695216 (1997-12-01), Sandstrom et al.
patent: 5799973 (1998-09-01), Bauer et al.
patent: 5931495 (1999-08-01), Rink et al.
patent: 0502630 A2 (1992-09-01), None
Carone Michael J.
Sanchez Glenda L.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Airbag Systems GmbH & Co. KG
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