Patent ID: 6199905
Filing Date: 2001-03-13
Classification: B60R,C06D

Abstract:
A high thermal efficiency inflator having a thermal efficiency of at least about 90 percent, the high thermal efficiency inflator comprising:a housing having an inner surface, and defining an interior volume, the housing containing a pressurized gas at a first pressure in the interior volume;a pyrotechnic material for producing heat upon combustion, having a burn rate that is accelerated at the first pressure in comparison to the burn rate at a pressure of one atmosphere, the pyrotechnic material stored within the interior volume of the housing at a distance from the inner surface of the housing, wherein the stored pyrotechnic material is subjected to the first pressure of the pressurized gas, wherein the pyrotechnic material in and of itself is free of thermal contact with the housing before the combustion thereof;an ignitor for initiating combustion of the pyrotechnic material upon receipt of an initiation signal; andmeans for maintaining the pressurized gas at the first pressure within the interior volume, and to open when the gas attains a predetermined second, higher pressure upon heating of the pressurized gas by combustion of the pyrotechnic material to allow an inflation gas to pass from the housing; whereinthe pyrotechnic material is present in an amount sufficient to produce at least about 10 mole percent of the inflation gas, and the pressurized gas is present in an amount sufficient to produce up to about 90 mole percent of the inflation gas; and whereinthe first pressure of the pressurized gas is sufficiently high to produce an aerodynamic drag on burning pyrotechnic material passing through the pressurized gas, thereby slowing the burning pyrotechnic material; whereinthe drag produced on the burning pyrotechnic material and the distance between the stored pyrotechnic material and the inner surface of the housing are sufficiently great that, upon combustion of the pyrotechnic material, contact between a sufficient amount of the burning pyrotechnic material and the inner surface of the housing is prevented to allow at least about 90 percent of the heat produced by the combustion of the pyrotechnic material to be transferred to the inflation gas, so that no more than about 10 percent of the heat is transferred to the housing, resulting in a thermal efficiency of the high thermal efficiency inflator of at least about 90 percent.