Pulsed pressure source particularly adapted for vehicle occupant air bag

Abstract

An occupant passive restraint system for an automotive vehicle comprises an air bag and a pulsed pressure source in fluid flow relation with the air bag. The pulsed pressure source includes plural pulsed pressure sources sequentially energized in response to the deceleration sensor sensing a single crash impact. Each source includes plural chambers holding progressively larger masses of gas generant. The chambers are arranged so that each has an outlet coupled with the chamber having the next largest gas generant mass. The gas generant mass in each chamber is predominantly a non-explosive solid particulate material. The smallest chamber includes a fuse in contact with the generant. When a crash is sensed the fuse is supplied with a pulse having sufficient energy and duration to rupture the fuse and form a plasma discharge in the generant in the smallest chamber. The plasma discharge has sufficient energy to ignite the generant in the smallest chamber to a vapor. Gas from each chamber sequentially flows into the chamber having the next largest gas generant mass to sequentially activate the generant mass in the next largest chamber. A temperature sensor controls energization of the pressure pulse to control when each pulse is derived and/or how many pulses are derived.