GAS GENERATOR

The present invention provides a gas generator(10), including: a cylindrical ignition device chamber housing(20) provided with a gas discharge port(27), accommodating an igniter(25) and a gas generating agent(38) therein, a cylindrical pressurized gas chamber housing(40) filled with pressurized gas, the cylindrical pressurized gas chamber housing being joined to the ignition device chamber housing(40) to form an outer shell container; a closing member(12) being provided with a fragile portion(11) and closing between the ignition device chamber housing(20) and the pressurized gas chamber housing (40) ; a multifunctional member(30) that is movable in an axial direction during activation being arranged inside the ignition device chamber housing(20) together with the igniter(25) and the gas generating agent(38), the igniter(25) closing an opening portion of the ignition device chamber housing(20) and being fixed thereto; the multifunctional member(30) having, a base plate portion(31) and a cylindrical wall portion(32) extending from one surface of the base plate portion(31), the cylindrical wall portion(32) having an opening portion at a distal end thereof the base plate portion(31) abutting against an inner wall surface(21) of the ignition device chamber housing(20) and having a first through-hole(33) in a thickness direction, and the cylindrical wall portion(32) having a smaller outer diameter than an outer diameter of the base plate portion(31), and being provided with a second through-hole(34) in the thickness direction thereof, the opening portion abutting against the fragile portion(11) of the closing member(12); a first plenum chamber(35) enclosed by the base plate portion(31), the cylindrical wall portion(32) and the closing member(12); a second plenum chamber(36) formed by a cylindrical space between an outer wall surface of the cylindrical wall portion(32) and the inner wall surface(21) of the ignition device chamber housing, and the gas discharge port(27) being provided in a circumferential wall portion of the ignition device chamber housing(20), to face the second plenum chamber(36); a gas generating agent charging chamber(37) enclosed by the base plate portion(31), the igniter(25), and the inner wall surface(21) of the ignition device chamber housing and charged with the gas generating agent(38), by pressure increase inside the ignition device chamber housing(20) due to combustion gas generated by combustion of the gas generating agent(38), the mu