Hybrid or pressurized inflation devices, commonly referred to as inflators, have been used to inflate airbags for years. These devices can be combined with gas generant to form a hybrid inflator that releases pressurized gas and simultaneously burns propellant to generate additional inflation gas.
Alternatively, no propellant or generant can be used in the inflation device and only the pressurized gas stored will be used.
In both these style inflators, an igniter or squib receives an electrical signal from a crash sensor and the igniter fires to rupture a seal to release the gas and optionally to ignite generant in the hybrid inflators.
To improve reliability, mechanical devices can be used to break a seal as taught in U.S. Pat. No. 5,076,607; U.S. Pat. No. 5,462,307 and U.S. Pat. No. 5,584,505; all using a mechanical piston. These pistons will reliably break a seal during impact, but can cause an erratic release of gases when the piston is moved into an opening blocking arrangement with the diffuser passages. This can cause an obstruction in one or more openings which can result in a problem with uniform gas flow and create thrust effects not anticipated in a normally thrust neutral diffuser. To avoid this, the diffuser has been positioned on a side or even at a far end. However, this makes the inflator bulky or longer than otherwise needed.
The present invention overcomes these short comings in a simpler and more efficient manner, that not only avoids any chance of an obstruction of flow openings, it also allows the inflator to use higher pressures and less expensive gases.