An air bag inflator providing a source of gas, releasable upon command, to inflate a supplemental inflation restraint (SIR)
system commonly known as an automobile air bag. Provided is a
pressure vessel containing one or more separate chambers for the purpose of storing gaseous fuel(s) and gaseous oxidizer(s) or
liquid fuel(s) and liquid oxidizer(s) under pressure with
helium as the primary filler gas. The primary function of the
helium gas is to serve as a kinetic
damper to modulate and control the
reaction rate of the fuel(s) and oxidizer(s). Because of its
low mass, high
thermal conductivity and
high heat capacity for its
mass,
helium is an excellent filler gas. In the case of the gaseous fuel(s) and oxidizer(s) a
single chamber is provided. In the case of
liquid fuel(s) and oxidizer(s), two or more separate housings are provided for storing the
liquid fuel(s) and oxidizer(s). Along with the liquid fuel(s) and oxidizer(s) housings, two separate chambers containing pressurized helium are provided within the
pressure vessel. The first helium chamber rapidly pressurizes upon
initiation of a gas producing pyrotechnic igniter. This pressure acts on thin membranes on the first chamber side of the separate
liquid storage housings to force the liquid fuel(s) and oxidizer(s) into the second chamber where the materials are atomized and mixed. The mixture is ignited by the arrival of hot gases from the igniter directed into the second chamber via the small
diameter tube or orifice. The fuel(s) oxidizer(s) mixture burns to produce gaseous reaction products that are released into the air bag by
bursting a controlled rupture burst disc.