Pyrotechnic linear inflator

Abstract

An inflator () for use in an inflatable vehicle occupant protection system. The inflator () includes a longitudinal enclosure () and a first gas generant () positioned along the enclosure (). Enclosure gas exit apertures () are arranged along the enclosure () to enable fluid communication between the enclosure () and an exterior of the enclosure. And to provide controlled venting of combustion gases from the enclosure () as the first gas generant composition () burns, thereby controlling the speed and direction of combustion propagation of the first gas generant. Combustion of the first gas generant () results in an inflator housing internal pressure of at least a first predetermined minimum internal pressure. The second gas generant composition () is also configured to combust to generate inflation gas providing at least a second predetermined minimum internal pressure in the housing, the second predetermined minimum internal pressure being higher than the first predetermined minimum internal pressure. As combustion of first gas generant () nears completion, flame from combustion of the first gas generant composition () reaches the end () of the enclosure () and contacts the second gas generant composition (), igniting the second gas generant () and producing a burst of gas and a resulting in an increase in inflator housing internal pressure. Gas exit apertures () along the housing () are sized such that the housing internal pressure is maintained at at least the first predetermined minimum level after passage of a predetermined time period after inflator activation.