4 ms·
It is not the force that changes, it is the rate of gas generation (burn rate). You need to generate airbag gasses fast enough to inflate before your face hits
by gvb 10y ago
It is not the force that changes, it is the rate of gas generation (burn rate). You need to generate airbag gasses fast enough to inflate before your face hits the airbag, but slow enough not to tear itself apart (especially the metal forming the gas generator).
As the ammonium nitrate based gas generator mix ages, becomes less stable in that it burns faster, generates its gasses faster, and crosses the threshold between gas generation and explosion (RUD).
Ref: https://en.wikipedia.org/wiki/Gas_generator https://en.wikipedia.org/wiki/Gas_generator
- hga 10y agoDoes it become less "stable", or just much higher in speed of detonation? I don't remember reading any accounts of these airbags going off when they shouldn't have, just bad results once the system triggered them.
- gvb 10y agoStability here is being used in the chemical sense, as in "how fast it oxidizes". https://en.wikipedia.org/wiki/Chemical_stability https://en.wikipedia.org/wiki/Chemical_stability A gas generator (airbag inflater) does not detonate, it generates a large volume of gas very rapidly but at a designed (predictable) rate - the faulty airbags are detonating. Spontaneous ("accidental") deployment would be the ultimate bad instability, but I don't believe this was a major problem (yet). IIRC, there was one reference to an "accidental" deployment which could be instability-related or a fault elsewhere, e.g. in the sensor/trigger circuitry. The instability that is causing the major problems is causing faster combustion than designed.