Gas generator

A gas generator comprising:

• a housing including a cylindrical circumferential wall portion provided with a gas discharge opening and a top plate portion and a bottom plate portion which close one and the other axial ends of the circumferential wall portion, the housing containing a combustion chamber which accommodates a gas generating agent;
• an igniter assembled to the bottom plate portion, the igniter including an ignition portion which accommodates an ignition agent ignited at time of activation;
• a cup-shaped member containing an enhancer chamber which accommodates an enhancer agent, the cup-shaped member being arranged to protrude toward the combustion chamber such that the enhancer chamber faces the ignition portion, a whole portion of the cup-shaped member which defines the enhancer chamber bursting or melting by combustion of the enhancer agent with activation of the igniter;
• a cylindrical filter located in the housing and arranged along an inner circumferential surface of the circumferential wall portion to surround the combustion chamber;
• and
• a fixing member which fixes the filter to the housing, the fixing member not bursting or melting even by combustion of the enhancer agent with activation of the igniter,
• the cup-shaped member including a cylindrical sidewall portion which defines the enhancer chamber and a top wall portion which defines the enhancer chamber and closes an axial end portion of the sidewall portion located on a side of the top plate portion,
• the fixing member including a base portion applied to the bottom plate portion along an inner bottom surface of the bottom plate portion, an abutment portion which abuts on an inner circumferential surface of the filter close to the bottom plate portion, and a cylindrical partition wall portion erected from the base portion toward the top plate portion,
• Ra and Ha satisfying a condition of Ra/Ha≤1.00 where Ra represents an inner diameter of the sidewall portion and Ha represents a distance between the top wall portion and the ignition portion along an axial direction of the circumferential wall portion,
• the sidewall portion including a first region located on a side of the bottom plate portion and surrounded by the partition wall portion and a second region located on a side of the top plate portion and not surrounded by the partition wall portion, by arranging the partition wall portion to reach a position in the combustion chamber intermediate along the axial direction of the circumferential wall portion,
• an end portion of the partition wall portion on the side of the top plate portion being arranged closer to the top plate portion than the ignition portion in the axial direction of the circumferential wall portion,
• the gas generating agent being arranged to face at least the top wall portion, the second region of the sidewall portion, and an outer circumferential surface of the partition wall portion, and wherein
• the partition wall portion includes a tapered portion tapered toward the top plate portion.