Inflator capable of modulation air bag inflation rate in a vehicle occupant restraint apparatus

摘要

In an occupant restraint apparatus for installation in a vehicle, a smart airbag inflator is provided with a piston for regeneratively pumping liquid propellant from a reservoir into a combustion chamber for ignition and combustion to generate airbag inflation gases. To control the airbag inflation rate, the piston includes a piston head slidingly received in a damping chamber filled with a magneto-rheological fluid that is pumped through an orifice during the regenerative pumping stroke of the piston. An electromagnet is selectively energized to produce a varying magnetic field to adjust the viscosity of the magneto-rheological fluid flowing through the orifice and thus vary a damping force exerted on the piston stroke, thereby modulating the rate of liquid propellant combustion. Electromagnet current excitation is controlled in response to a particular accident scenario.