Air bag inflator

An air bag inflator comprising

• a cup shaped body having an annular wall defining a combustion chamber;
• a pump piston mounted in said body;
• an injection piston slidably mounted in said wail and slidably mounted on said pump piston to define a propellant chamber therewith, said injection piston having at least one nozzle communicating said propellant chamber with said combustion chamber to deliver liquid propellant thereto, and means for releasably closing said nozzle to prevent communication between said propellant chamber and said combustion chamber;
• a magnetic control unit for controlling movement of said injection piston relative to said pump piston, said magnetic control unit including a sleeve disposed concentrically of said wall, a core disposed in and concentrically spaced from said sleeve to define a gap therebetween, a reservoir for magneto-rheological fluid between said injection piston and said gap and communicating with said gap to deliver the fluid thereto in response to said injection piston moving from said initial position towards said second position, and at least one electromagnetic coil for producing an electromagnetic field across said gap to affect the rheological properties of a magneto-rheological fluid in said gap whereby an increase in the electromagnetic field effects an increase in the flow resistance of the magneto-rheological fluid in said gap;
• a contoured plate secured to said annular wall of said cup shaped body at one end thereof, said plate having at least one exhaust port for expelling combustion gasses therefrom;
• and
• an initiator mounted in said plate for introducing a combustion gas into said combustion chamber.

An air bag inflator comprising

• means defining a first combustion chamber;
• an initiator for introducing a combustion gas into said first combustion chamber;
• a housing having an annular wail defining an annular combustion chamber about and in communication with said first combustion chamber to receive hot combustion gases therefrom;
• an annular pump piston mounted in said annular combustion chamber;
• an annular injection piston slidably mounted on said pump piston to define an annular liquid propellant chamber therebetween, said injection piston being slidably mounted in said annular wall and slideably mounted on said means defining a first combustion chamber, said injection piston having at least one nozzle communicating said propellant chamber with said annular combustion chamber to deliver liquid propellant thereto, and means for releasably closing said nozzle to prevent communication between said propellant chamber and said annular combustion chamber;
• a magnetic control unit for controlling movement of said injection piston relative to said pump piston, said magnetic control unit including a sleeve disposed concentrically of said wall of said housing, a core disposed in and concentrically spaced from said sleeve to define a gap therebetween, a reservoir for magneto-rheological fluid between said annular injection piston and said gap and communicating with said gap to deliver the fluid thereto in response to said injection piston moving over said pump piston, and at least one electromagnetic coil for producing an electromagnetic field across said gap to affect the rheological properties of a magneto-rheological fluid in said gap whereby an increase in the electromagnetic field effects an increase in the flow resistance of the magneto-rheological fluid in said gap;
• and
• an annular plate secured between said means and said housing to close said annular combustion chamber, said plate having at least one exhaust port therein communicating with said annular combustion chamber to exhaust combustion gases therefrom.

An air bag inflator having

• a diameter larger than the thickness thereof;
• means defining a combustion chamber;
• an initiator for introducing a combustion gas into said combustion chamber;
• an injection piston slidably mounted in said combustion chamber for movement from an initial position towards a second position in response to the introduction of a combustion gas into said combustion chamber from said initiator;
• and
• a magnetic control unit concentrically disposed about said injection piston for controlling movement of said injection piston from said initial position towards said second position.

An air bag inflator comprising

• means defining a combustion chamber;
• an initiator far introducing a combustion gas into said combustion chamber;
• an injection piston slidably mounted in said combustion chamber for movement from an initial position towards a second position in response to the introduction of a combustion gas into said combustion chamber from said initiator, said piston including a propellant chamber therein for containing a charge of liquid propellant therein at least one nozzle communicating said propellant chamber with said combustion chamber to deliver liquid propellant thereto, and means for releasably closing said nozzle to prevent communication between said propellant chamber and said combustion chamber;
• a pump piston fixedly mounted in said injection piston for sliding of said injection piston thereon to pressurize a liquid propellant in said propellant chamber in response to sliding of said injection piston towards said second position;
• and a magnetic control unit concentric to said injection piston for controlling movement of said injection piston from said initial position towards said second position.