Dual stage air bag inflator

An inflator for providing inflation fluid for inflating an inflatable vehicle occupant protection device, said inflator comprising:

• a primary housing having an upper wall and a lower wall opposite said upper wall, said primary housing being constructed from sheet metal by stamping;
• a primary inflation fluid source disposed within said primary housing actuatable to deform said primary housing to move said upper wall and said lower wall away from each other;
• a secondary housing constructed from sheet metal by stamping, said secondary housing being disposed within said primary housing, said secondary housing having an upper portion abutting said upper wall of said primary housing and a lower portion abutting said lower wall of said primary housing prior to actuation of said primary inflation fluid source;
• and
• a secondary inflation fluid source disposed within said secondary housing actuatable to move said upper portion of said secondary housing at least partially out of engagement with said lower portion of said secondary housing subsequent to said primary housing being deformed by said primary inflation fluid source.