Filter unit for gas generator, gas generator, and method for manufacturing gas generator

A method for manufacturing a gas generator, the method comprising:

• preparing a filter unit for a gas generator, the filter unit including a filter having a columnar outer shape, and a filter housing accommodating the filter in a filter accommodating space formed inside the filter housing, the filter being accommodated in a coaxially positioned and fixed state;
• preparing a combustion chamber housing unit including a combustion chamber housing having a tubular shape in which a combustion chamber accommodating a gas generating agent is formed;
• and
• attaching the filter unit for a gas generator to one end of the combustion chamber housing, wherein
• the filter housing includes a first restraining end part, a second restraining end part, and a peripheral wall part connecting the first restraining end part and the second restraining end part, the first restraining end part, the second restraining end part, and the peripheral wall part being integrally formed,
• the peripheral wall part includes a non-restraining peripheral wall part in which a gas discharge port is disposed, and a restraining peripheral wall part restraining a peripheral surface of the filter, and
• when the filter unit for a gas generator is prepared, a one axial end surface of the filter is restrained by disposing the first restraining end part as a closing surface at one end of the filter housing, an other axial end surface of the filter is restrained by disposing the second restraining end part at an other end of the filter housing, surrounding a gas inflow port, the non-restraining peripheral wall part is disposed apart from the peripheral surface of the filter thereby forming an annular gap between the non-restraining peripheral wall part and the peripheral surface of the filter, and the peripheral surface of the filter is restrained by the restraining peripheral wall part, and
• wherein the restraining peripheral wall part is parallel to the non-restraining peripheral wall part, and an annular stepped part connects the restraining peripheral wall part and the non-restraining peripheral wall part.