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The Temperature Compensated Stored Gas inflator provides output gas which is completely clean and cool, with significantly narrower temperature dependence than a traditional stored gas inflator. During discharge, the exiting gas which has been cooled by decompression can be reheated by flowing through a passive thermal reservoir. A valving device maximizes this heat addition at cold initial conditions and minimizes heat addition at hot initial conditions. The inflator is simple in principle with few parts, completely free of particulate emissions, and environmentally attractive. Pulse-shaping is also provided by mechanical means.

An analytical model is described which predicts the performance of a pyrotechnic airbag inflator by accounting for the heat transfer, filtration, combustion, fluid flow and thermodynamic processes occurring during operation. The dynamic system has many interrelationships among the variables describing these processes and also their histories. A detailed energy accounting highlights the role of the filter as a heat exchanger. The role of filter clogging is also discussed. The nonlinear variation of tank pressure with mass of gas generating material is explained, as is the phenomenon where inflators having similar tank pressures produce different airbag pressures even in an unvented airbag.