Passenger automotive restraint generator

Abstract

An impact extruded perforated aluminum housing contains a two-stage gas generator having a perforated bulkhead positioned between the stages. Each stage includes a combustion chamber having an igniter and pyrotechnic charge therein with cooling and filter screens surrounding the combustion chamber. The igniter of the first stage is fired by a squib responsively to an external electrical signal. A rupturable barrier and a ball valve associated with the bulkhead control the flow of gas through the bulkhead and provide mechanical timing for ignition delay in the firing of the second stage after the first stage has been fired, and also provide pressure control after ignition of both stages to prevent repressurizing the first stage. A rupturable foil barrier surrounding the combustion chamber in the first stage promotes a rapid rise in pressure therein and thus breakout sooner therefrom of gas to an airbag to be inflated. A rupturable foil barrier surrounds the cooling and filter screens in the second stage and delays the breakout of gas therefrom to the airbag as the pressure rises, the rate of which pressure rise is less than that at which the pressure in the first stage rises. The thickness of the foil barrier surrounding the combustion and filter screens is selected to be sufficiently less than that of the foil barrier surrounding the first stage combustion chamber so as to achieve substantial equalization of pressure in the first and second stages.