Patent ID: 7175197

Claim:
A gas generator for an air bag, comprising: a cylindrical housing having a gas discharging port; an inner cylindrical member disposed inside the cylindrical housing; ignition means disposed inside the inner cylindrical member; and a first combustion chamber provided outside the inner cylindrical member to accommodate a first gas generating agent; a retainer provided inside the housing and extending from the inner cylindrical member in a radial direction of the gas generator without making contact with the housing, the retainer being provided with a partition wall surface that defines an average length of the first combustion chamber in an axial direction of the gas generator; and a partition wall that divides an inside of the inner cylindrical member into an ignition means accommodating chamber and a second combustion chamber that accommodates a second gas generating agent, wherein, a ratio (D/L) of an average distance (D) in a radial direction of the first combustion chamber to the average length (L) is in a range of 0.2 to 2.0, and wherein a gas generated by the second gas generating agent is discharged from the gas discharge port without passing through the first combustion chamber.