An airbag assembly may include an airbag and an inflator that provides inflation gas to inflate the airbag. A filter module may be positioned such that inflation gas exiting the inflator must first pass through the filter module. The filter module may be formed of a sheet of metal that is wrapped into a generally spiraling tubular shape. The filter module may have an inner layer, an intermediate layer, and an outer layer. The intermediate layer generally encircles the inner layer, and the outer layer generally encircles the inner layer and the intermediate layer in a spiraling fashion. The inner layer, the intermediate layer, and the outer layer each may have a pattern of holes and dimples that are separate from and/or displaced from each other. The dimples may protrude toward an adjacent layer to maintain spacing to enable relatively unrestricted gas flow from the holes of the inner layer through unaligned holes of the intermediate layer and the outer layer. The resulting tortuous gas flow path may help to slow, cool, and/or purify the gas before it exits the inflator.

The invention relates to a gas generator (10) for a vehicle occupant safety system comprising an outer casing (20) and a filter structure (30) for purifying and/or cooling gas released inside the outer casing (20), wherein the filter structure (30) is integrated in the outer casing (20). The invention further relates to an airbag module and a vehicle occupant safety system comprising said gas generator as well as to a manufacturing method.

Expanded metal sheets (5) are used to produce tubular filters (13). The expanded metal sheet (5) has a multiplicity of rows of openings arranged to reduce nesting when the sheet (5) is rolled on itself. In particular, the pitch between the rows of openings, the sizes of the openings, or both the pitch between the rows of openings and the sizes of the openings are varied to reduce nesting when the expanded metal sheet (5) is rolled on itself. The filters (13) can include external circumferential grooves (3), rounded corners (19) produced by a point loading process, textured surfaces (37) between openings, and/or torturous internal paths produced by non-perforated areas of an expanded metal sheet. The expanded metal sheet (5) can be composed of carbon steel coated with a material having a higher heat conductivity, e.g., tin.

An object of the present invention is to make a joined portion of a metal wire less likely to catch on other components and the like. A hollow cylindrical filter 200 is formed by winding one or a plurality of metal wires 220 in a helical and multilayered manner so that metal wire portions adjacent to each other in a direction toward an inner or outer diameter side extend in directions crossing each other. The filter includes a deformed joining part 231 including a first metal wire portion 220A having been pressed and deformed and a second metal wire portion 220B having been pressed and deformed via the first metal wire portion and joined to the first metal wire portion by resistance spot welding, where the deformed joining part penetrates into a communication space positioned at an inner side of the deformed joining part. Since the metal wire is pressed and deformed at the deformed joining part, the deformed joining part is less likely to catch on other components and the like during handling of the filter.

A flattened expanded metal strip (9) is wrapped into an airbag inflator filter (21) with the strip oriented such that the flattened rough side (17) of the strip is pointing toward the inside diameter (ID) of the filter and the flattened smooth side (15) is pointing towards the outside diameter (OD). With this orientation, the filter (21) is able to capture more slag than filters made using the standard wrapping method in which the smooth side is oriented inward. The expanded metal can be of various types including, for example, variable expanded metal (VEM) or standard expanded metal (SEM).

A filter unit for a gas generator includes a filter and a filter housing coaxially positioning and fixing the filter in a filter accommodating space. The filter housing includes a first restraining end part disposed as a closing surface at one end of the filter housing and restraining a one axial end surface of the filter, a second restraining end part disposed at an other end of the filter housing, surrounding a gas inflow port, and restraining an other axial end surface of the filter, and a peripheral wall part connecting the first restraining end part and the second restraining end part and including a gas discharge port. The peripheral wall part includes a restraining peripheral wall part restraining a peripheral surface of the filter, and a non-restraining peripheral wall part in which the gas discharge port is disposed.

A flattened expanded metal strip (9) is wrapped into an airbag inflator filter (21) with the strip oriented such that the flattened rough side (17) of the strip is pointing toward the inside diameter (ID) of the filter and the flattened smooth side (15) is pointing towards the outside diameter (OD). With this orientation, the filter (21) is able to capture more slag than filters made using the standard wrapping method in which the smooth side is oriented inward. The expanded metal can be of various types including, for example, variable expanded metal (VEM) or standard expanded metal (SEM).

A cylindrical filter for a pyrotechnic device, including a gas generating agent or pressurized gas as a gas generation source, includes a first annular end surface, a second annular end surface positioned opposite to the first annular end surface, and a cylindrical wall surface between the first annular end surface and the second annular end surface. At least one of the first and second annular end surfaces includes a weakened portion. The weakened portion, when provided in the first annular end surface, includes a first annular wall portion protruding from the first annular end surface and has a thickness less than a thickness of the first annular end surface. The weakened portion, when provided in the second annular end surface, includes a second annular wall portion protruding from the second annular end surface and has a thickness less than a thickness of the second annular end surface.