Patent ID: 7055855

Claim:
A multistage gas generator for an air bag, comprising: a cylindrical housing having at least one first gas discharging port and at least one second gas discharging port; a first inner cylindrical member disposed inside the cylindrical housing and provided, in a peripheral wall thereof, with first flame-transferring holes, both end portions of the first inner cylindrical member being in contact with the cylindrical housing; a second inner cylindrical member disposed inside the cylindrical housing and provided, in a peripheral wall thereof, with second flame transferring holes, both end portions of the second inner cylindrical member being in contact with the cylindrical housing; a first combustion chamber provided inside the cylindrical housing and accommodating a first gas generating agent therein; a second combustion chamber provided inside the cylindrical housing and on top of the first combustion chamber with respect to an axial direction of the cylindrical housing and accommodating a second gas generating agent therein, the second combustion chamber being defined separately and without communication with the first combustion chamber, such that a first gas generated in the first combustion chamber is discharged only through the at least one first gas discharging port and a second gas generated inside the second combustion chamber is discharged only through the at least one second gas discharging port; first igniting means adapted to ignite the first gas generating agent accommodated inside the first combustion chamber; and second igniting means adapted to ignite the second gas generating agent accommodated inside the second combustion chamber.