The present invention provides a
gas generator in which ignition and
combustion performance of a gas generating agent and operation performance are enhanced. An inner cylindrical member 4 is disposed in a cylindrical housing 3, an annular first
combustion chamber 5a is provided radially in the outside of the inner cylindrical member 4, and, in the
combustion chamber 5a, a ratio (D / L) of its radial average distance (D) to its axial average length (L) is adjusted to be in the range of 0.2 to 2.0. The invention provides a
gas generator for an air bag capable of reducing a size of the
gas generator and easily and reliably adjusting a capacity of a
combustion chamber which accommodates the gas generating agent, and also provides a
retainer for such a gas generator. The invention provides a
retainer which changes a flow of a gas ejected from a through-hole of an inner cylindrical member provided in the housing and has a cylindrical portion for collecting fluid and semifluid
combustion products included in the gas, and provides a gas generator for an air bag using such a
retainer. The invention provides a gas generator for an air bag comprising, in a housing having a gas discharging port, a inner cylindrical member having a cylindrical
peripheral wall, and two combustion chambers defined by the inner cylindrical member, in which a gas generating agent to be ignited for generating a working gas is charged in the respective combustion chambers, and working gases generated in the respective combustion chambers pass through different flow-paths and reach the gas discharging port. The present invention further provides a gas generator for an air bag in which, in a housing having a gas discharging port, an inner cylindrical member having a cylindrical
peripheral wall is disposed, two combustion chambers are defined by the inner cylindrical member, a gas generating agent which is burnt to generate a working gas is charged in each of the combustion chambers, and working gases generated in the respective combustion chambers pass through different flow-paths to reach a
coolant means.