Explosive and thermic compositions or charges – Structure or arrangement of component or product – Solid particles dispersed in solid solution or matrix
Reexamination Certificate
1999-02-17
2001-05-15
Nelson, Peter A. (Department: 3641)
Explosive and thermic compositions or charges
Structure or arrangement of component or product
Solid particles dispersed in solid solution or matrix
C149S045000, C149S046000
Reexamination Certificate
active
06231701
ABSTRACT:
BACKGROUND OF THE INVENTION
An inflator for inflating an inflatable vehicle occupant protection device, such as an air bag, contains an ignitable gas generating material. The inflator further includes an igniter. The igniter is actuated so as to ignite the gas generating material when the vehicle experiences a collision for which inflation of the air bag is desired. As the gas generating material burns, it generates a volume of inflation gas. The inflation gas is directed into the air bag to inflate the air bag. When the air bag is inflated, it expands into the vehicle occupant compartment and helps to protect the vehicle occupant.
U.S. Pat. No. 5,060,973 discloses a vehicle occupant restraint apparatus which comprises a liquid gas generating composition. The composition comprises 60% hydroxyl ammonium nitrate (HAN) as an oxidizer, 20% triethanol ammonium nitrate (TEAN) as a fuel, and 20% water. The HAN and TEAN are water soluble.
U.S. Pat. No. 5,223,057 discloses a liquid monopropellant suitable for underwater and surface propulsion of ordnance vehicles. The composition comprises a solution or emulsion of hydroxyl ammonium nitrate (HAN), a water soluble fuel, and water. A number of fuels are listed such as alcohols, glycols, and amines. The amount of water is about 5% to 100% of the combined weight of fuel and oxidant, and functions as a desensitizing agent for the HAN and serves to provide cooling to control the flame temperature of the combustion reaction.
U.S. Pat. No. 5,451,277 discloses a method for preparing solid energetic compositions using liquid oxidizers. Hydroxyl ammonium nitrate (HAN) is listed as a suitable liquid oxidizer. Solid fuel particles such as a metal fuel are coated with a polyvinyl alcohol coating. The polymer-coated particles are dried and then combined with the liquid oxidizer forming a dispersion. The dispersion is cast into a mold. The liquid oxidizer is absorbed by the polymer coating causing aggregation of the dispersion into a rubbery solid mass.
U.S. Pat. No. 5,684,269 discloses a liquid gas generating composition suitable for automotive restraint systems. The composition comprises HAN and a nitrate salt of an amine such as an amino tetrazole.
U.S. patent application Ser. No. 09/052413 discloses a gas generating material comprising a solid solution of a water soluble liquid oxidizer, a hyrophilic gelling agent, and water in an amount of up to about 25% based on the weight of the gas generating material. The gelling agent comprises an effective amount of carbon atoms to form a combustible mixture with the liquid oxidizer in the gas generating material.
SUMMARY OF THE INVENTION
An apparatus for inflating a vehicle occupant protection device comprises a gas generating material. The gas generating material comprises a solid solution of a water soluble liquid oxidizer, a cross-linked hydrophilic polymeric gelling agent, and water. The cross-linked hydrophilic polymeric gelling agent comprises an effective amount of carbon atoms to provide a combustible mixture with the liquid oxidizer. The cross-linked hydrophilic polymeric gelling agent forms a reticulated structure in which the liquid oxidizer and water are immobilized.
The water reduces the temperature of the gas which is produced by combustion of the combustible mixture and also increases the volume of gas, making the gas generating material of the present invention suitable for inflating a vehicle occupant protection device.
In a preferred embodiment of the present invention, the liquid oxidizer is hydroxyl ammonium nitrate and the cross-linked hydrophilic polymeric gelling agent is cross-linked polyvinyl alcohol.
Preferably, the body of gas generating material comprises about 50% to about 90% by weight of the liquid oxidizer, about 5% to about 25% by weight of cross-linked hydrophilic polymeric gelling agent and about 1% to about 5% by weight of water.
Preferably, the ratio of cross-linked polyvinyl alcohol to hydroxyl ammonium nitrate is that ratio which is effective for combustion of carbon in the cross-linked polyvinyl alcohol to carbon dioxide.
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Nelson Peter A.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
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