Image Number 4 for United States Patent #5441302.
The invention is a low cost inflator having a thin-walled hermetic liner, filled with either a stored gas or a flammable fluid mixture, and having a minimal number of joints required for sealing. Structural support is provided by parts that are not required to be hermetic. To activate the inflator, a small amount of pyrotechnic is used to move a piston, crushing the thin-walled liner and compressing the stored inert gas, or alternatively compressing and igniting the stored flammable fluid mixture, causing the gas to escape into the air bag. Optionally, the stored inert gas or flammable fluid mixture can be augmented by hot gases produced by the pyrotechnic. The piston-driving material may be composed of a wide variety of pyrotechnic materials, combustible mixtures of fluid fuels and oxidants, or compatible combinations of both. The inflator design incorporating a stored combustible fluid mixture will, upon ignition of the mixture, produce a heated gas able to more quickly inflate the air bag, as compared to a cold gas or blow down system of the same size and pressure. The combustible fluid mixture is selected so that while production of undesirable incomplete products of combustion and particulate matter are minimized, the fluid mixture must be compressed to ignite, thereby eliminating storage and handling issues problematic to some inflators featuring combustible fluid mixtures.