EXPANDABLE SPIRAL FILTER

A filter or trap especially adapted for removing lint and other foreign material from a liquid, such as wash water in an automatic domestic washing machine having wash and drain cycles, includes a circular flow path along a housing surface, and a generally spiral segment flexible filter element cooperates with said surface responsive to the liquid flowing in one direction to close in filtering relation toward the surface and movable into spaced flushing relation to the surface during reverse flow of the liquid. By anchoring the filter element adjacent a port from which filtered liquid passes in operation, the element controls the liquid flow compelling substantially all of the liquid to traverse the filter before reaching the port. Conversely, liquid entering the housing through such port is compelled to sweep the filter element in flushing, cleaning relation.