Abstract: 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.

Abstract: To achieve a reduced inflation rate of an airbag in a vehicle occupant restraint apparatus, an airbag inflator is provided with a seal ring acting, in response to initial pressurization by a pyrotechnic initiator, to open injection ports, such that liquid propellant may be regeneratively pumped by a piston from a reservoir into a combustion chamber for combustion. The resulting combustion gases flow through a series of swirl chambers to increase residence time and through a plenum chamber where the combustion gases are cooled. The combustion gases exit the plenum chamber as an airbag inflation gas.

Abstract: An apparatus for deploying an inflatable member, such as a safety bag in a motor vehicle, includes a hydraulic actuator for amplifying the fluid pressure in a combustion chamber, initially generated by a pyrotechnic initiator, and applying the amplified fluid pressure to continuously pressurize a liquid propellant reservoir to magnitudes exceeding the combustion chamber fluid pressure. All of the liquid propellant in the reservoir is then rapidly injected as a continuous stream into the combustion chamber for ignition and sustained combustion, thereby generating the volume of combustion gases necessary to fully inflate the safety bag.

Abstract: To achieve programmed inflation of an airbag in a vehicle occupant restraint apparatus, movement of a piston, that separates a combustion chamber from a liquid propellant reservoir, is utilized to vary the opening size of an injection port through which liquid propellant is regeneratively pumped from the reservoir into the combustion chamber for combustion, such that the rate at which the bag inflation gas is generated during an inflation period may be controlled.