Ammunition and explosives – Jacketed or cartridge gas generator
Reexamination Certificate
1998-08-17
2001-07-03
Carone, Michael J. (Department: 3643)
Ammunition and explosives
Jacketed or cartridge gas generator
C280S737000, C280S741000
Reexamination Certificate
active
06253683
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a gas generator for an air bag that protects a driver or a passenger from an impact, and more particularly to a hybrid-type gas generator that seals pressurized gas therein.
DESCRIPTION OF THE PRIOR ART
For the purpose of protecting a driver or a passenger from an impact of a vehicle collision, a vehicle is equipped with an air bag device. The air bag device includes a sensor, a control unit, gas generator, an air bag, etc. The gas generator includes an igniter and gas generating means. In the hybrid-type gas generator, the gas generating means includes a gas generating agent and a pressurized gas.
Upon detection of an impact by the sensor, a detection signal is supplied to the control unit, which conducts arithmetic operation in response to the detection signal. The control unit generates an output signal representative of the result of the arithmetic operation to the igniter. The igniter is thus operated. With this operation, the gas generating agent of the gas generating means is burned to generate a gas having a high temperature and a high pressure. The combustion gas heats the pressurized gas and mixes with the pressurized gas, and the mixed gas is injected into the air bag (bag body). As a result, the air bag is inflated to form a cushion that absorbs an impact between a solid structure and the driver or passenger.
Because of the rapid combustion of the gas generating agent, the mixed gas generated by the combustion inflates the air bag rapidly. The rapid inflation of the air bag may apply a sudden and large impact to a small child when he or she is not in a regular seating posture.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a gas generator for an air bag which can change the inflation pattern of the air bag in accordance with circumstances.
There is provided a gas generator for an air bag of the present invention including two gas generating units being connected axially, each of said gas generating units, comprising: a cylindrical housing; an igniter disposed in one end of said cylindrical housing and operates upon receiving an operation signal; a gas generating agent ignited by the igniter to generate a combustion gas; a pressurized gas sealed within the housing and heated by the combustion gas of the gas generating agent to generate a mixture gas together with the combustion gas; and a diffuser having a gas exhaust outlet disposed at the other end of the housing and from which the mixture gas within the housing is exhausted, wherein the two gas generating units are joined together at the diffuser sides of the housings of the respective gas generating units by welding.
Also, it is preferable that each of the diffusers of the gas generating units are made of a cylindrical member including an end wall portion having a joint surface and a peripheral wall portion having the gas exhaust outlet.
Further, these two gas generating units may have the same structure.
Still further, both of the amount of the gas generating agent and the volume of the pressurized gas or either of them may be different between the two gas generating units.
The gas generator for an air bag is so arranged that two gas generating units are connected to each other in their axial direction. Each of the two gas generating units includes the cylindrical housing, the igniters, the gas generating means, that is, the gas generating agent and the pressurized gas, and the gas exhaust outlet. Those two gas generating units are joined together by welding the respective other ends together at which the respective gas exhaust outlets are defined.
The gas generator of the present invention can change an inflating (deploying) rate of the air bag by operating the two igniter at the same time or with a time lag.
When the degree of an impact is small, two igniters operate with a time lag, thereby decreasing the inflating rate of the air bag at an initial state of deployment. As a result, a small force is applied to a driver or a passenger who is not at a regular seating posture, and a large force is thereafter applied so that he returns to the regular seating posture. Thus, a cushion can be formed in front of the driver or the passenger.
Moreover, when the degree of an impact is large, two igniters operate simultaneously, thereby increasing the inflating rate of the air bag. As a result, the air bag is inflated rapidly, thereby forming a cushion in front of the driver or the passenger.
Furthermore, in the gas generator of the present invention, when only one of two igniters operate, the amount of gas supplied to the air bag can be reduced.
For example, when a room temperature of the vehicle is high, the air bag is inflated by an excessive internal pressure. In such a case, only one igniter operates so that one of two gas generating units operates, thereby reducing the amount of gas supplied to the air bag. By operating the gas generating unit in this matter, the air bag can be inflated with an appropriate internal pressure.
The igniter may be disposed at the one end of the housing opposite to the gas exhaust outlet or at the other end of the housing that is at the same side as the gas exhaust outlet.
The joining of two gas generating units can be conducted by a variety of welding techniques, for example, gas welding, arc welding, inert gas arc welding, friction welding, etc. It is preferable that the end of the housing to which welding is conducted is made of a cylindrical member including an end wall portion having a joint surface and a peripheral wall portion having the gas exhaust outlet. Those two generating units are put together on the above-mentioned joint surfaces to be welded.
The pressurized gas provided in the gas generator of the present invention may be an inert gas, such as argon, helium, or the like.
As stated in the foregoing, according to the present invention, a gas generator for an air bag capable of changing deployment patterns of the air bag is realized. In other words, the gas generator of the present invention can vary gas providing speed and gas providing amount by controlling the operation of the igniters, thereby changing the deployment patterns of the air bag.
Further, since, in the gas generator of the present invention, the gas exhaust outlet is provided in the center portion of the gas generator assembly, an even deployment of the air bag can be achieved resulting in a safe protection of the driver/passenger.
REFERENCES:
patent: 5219178 (1993-06-01), Kobari et al.
patent: 5516147 (1996-05-01), Clark et al.
patent: 5533751 (1996-07-01), Kort et al.
patent: 5582428 (1996-12-01), Buchanan et al.
patent: 5630619 (1997-05-01), Buchanan et al.
patent: 5709406 (1998-01-01), Buchanan
patent: 5794973 (1998-08-01), O'Loughlin et al.
Research Disclosure, Apr. 1998, The Int. Journal for Co.'s seekin an alternative or supp. to obtaining patents, p. 361.
Carone Michael J.
Daicel Chemical Industries Ltd.
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