Patent ID: 7763092

Claim:
A filter for an air bag gas generator comprises: a first layer formed by helically winding a wire rod having a cross-sectional area of 0.03 to 0.8 mm 2 in such a way that a pitch angle of wire rods vertically superposed in the radial direction is symmetrical; a second layer disposed on the outer side of the first layer in the radial direction and formed to have a finer filter particle size than the first layer, and a third layer disposed on the outer side of the second layer in the radial direction, wherein the second layer is formed by winding a wire rod having a smaller cross-sectional area than the wire rod that forms the first layer to form a wire mesh, projects in an axial direction beyond the end surfaces of the first and third layers, and is formed by winding the wire mesh one to three times around the outer side of the first layer, the third layer is formed from a wire rod having a larger cross-sectional area than the wire rod of the second layer on the outer side of the second layer, the first layer, the second layer and the third layer are sintered to integrate the layers.