Filter device for filtering a gas flow

A filter device for filtering a gas flow, especially for filtering the gases produced by a gas generator for an impact protection cushion, comprises a filter element exhibiting several filter material plies of varying permeability lying in series in the flow direction. The filter element is fashioned as a wrapped member produced by winding up a length of filter material. The length of filter material has sectionally different filter materials, preferably wire mesh of differing mesh widths and metal fiber mats. A wrapped member is formed by winding up this filter material web, the wrapping plies of which consist of different materials with varying filter effects. This filter element wrap is inserted, for example, in the annular interspace between the two tubes of a double-tube gas generator. Owing to the rising pressure of the gas to be cleaned, the wrapped member is compacted with the consequence that its filtering function is improved.