Ammunition and explosives – Jacketed or cartridge gas generator
Reexamination Certificate
1999-11-23
2001-10-09
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Jacketed or cartridge gas generator
C102S531000, C280S737000, C280S741000, C280S740000, C149S001000, C149S074000
Reexamination Certificate
active
06298789
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention refers to a gas generator, preferably for an inflatable airbag for the protection of vehicle occupants, consisting of a container holding a combustible gas mixture and provided with a closure which opens into a combustion chamber provided with a as outlet in which the gas mixture is ignited by an ignition device.
In a gas generator of said kind which is known from DE 41 35 776 C1, the container contains a liquid gas consisting of a mixture of one or several short-chain hydrocarbons and dinitrogen monoxide as an oxidizing agent, which is injected into the combustion chamber after the initiation of the gas generator and is ignited therein by an ignition device with an ignition charge. Thereby the ignition clouds and the hot combustion gases ignite the liquid gas which vaporizes and volatilizes due to the occurring expansion in the combustion chamber. In the known gas generator, the ignited gas mixture shows an explosion-like reaction so that gas pressure peaks destroying the combustion chamber may occur. Thus, in order to reduce the high reaction velocity, in the known gas generator an inert gas of carbon dioxide and/or xenon is added to the gas mixture in an amount of preferably 10 through 80% in weight.
The known gas generator is not only detrimental because of the high reaction velocity which is only mitigated by the addition of inert gas, but also because of the use of liquid gas which has to evaporate prior to its ignition so that the supply of additional energy is necessesary. Said evaporation is time-consuming. Furthermore, the high concentration of fuel gas results in a very high temperature of the combustion gases, which is an additional risk if leaks should occur.
SUMMARY OF THE INVENTION
Consequently, it is the object of the invention to provide a gas generator of the kind mentioned at the beginning which, after the initiation of the ignition device, shows a fast reaction, generates a controllable flow of pressurized gas at a relatively low temperature and also is completely safe.
In order to obtain an even better and more efficient combustion, a catalytic coating (for instance Pt or Rh) can be provided at sections of the combustion chamber.
According to the invention, said problem is solved by the fact that the container is mainly filled with a pressurized inert gas and contains 0.1 to 5.0% vol. of a gaseous fuel and 0.5 through 20% vol. of a gaseous oxidizing agent, and that the ignition device, on being actuated, opens the container closure, ignites the gas flowing into the combustion chamber and maintains combustion by a continuous supply of energy. The upper limit values are chosen so that at no time an explosive mixture is obtained.
Due to the low concentration of the amounts of combustible gas and gaseous oxidizing agent in the total mixture of gases, the combustion of the gas mixture flowing into the combustion chamber is not automatically maintained after the initiating ignition so that the ignition device has to maintain the combustion of the gas mixture in the combustion chamber. Nevertheless, the inventive gas generator generates a gas flow with the required flow rate, as the gas flowing into the combustion chamber is ignited immediately and needs not to be evaporated first, in order to form an ignitable mixture. Due to the high amount of inert gas in the gas mixture and due to the use of a catalyst, the temperature of the combustion gas can be kept low, for instance in the range of 400° C. or less.
According to a preferred embodiment it is provided that at least half of the gaseous fuel is hydrocarbon or hydrogen. The combustible gas may consist of CH
4
, C
2
H
6
, C
3
H
8
, C
2
H
10
, or H
2
or of a mixture thereof, but preferably consists of CH
4
or C
3
H
8
.
The gaseous oxidizing agent advantageously consists of O
2
, N
2
O or H
2
O
2
.
Advantageously, the oxidizing agent is O
2
.
The inert gas preferably is Ar, but also N
2
may be used.
According to a particularly favorable embodiment it is provided that the gaseous fuel contains 0 through 70% vol., preferably approximately 50% vol., of saturated hydrocarbon, and in addition an unsaturated hydrocarbon, for instance C
2
H
2
or C
2
H
4
.
The addition of unsaturated hydrocarbons results in a better ignition of the gas mixture so that it is used for the initiation and the acceleration of the combustion of the gas mixture which contains alkanes and oxidizing agents.
Advantageously, the pressure of the gas mixture in the container amounts to 100 through 300 bar and preferably to approximately 180 through 280 bar.
The ignition device may consist of a solid or liquid pyrotechnic charge arranged externally of the container.
As an ignition device also a laser can be used.
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Ericsson Dan
Gastiger Michel
Karinthi Pierre
Autoflator AB
Dilworth & Barrese LLP
Jordan Charles T.
Sanchez Glenda L.
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