US Patent RE40481 Air filtration device for internal combustion engine

Filtration method and device for filtering solid contaminants from a stream of a flowing fluid such as internal combustion engine intake air. An imperforate housing has a tubular inlet exiting at its downstream end into a conically divergent first wall section terminating in a maximum diameter apex. A convergent second wall section terminates at a housing outlet opening of greater diameter than that of the housing inlet. A perforate filter element disposed within the housing conical portions has an exterior configuration generally complimental to the housing interior, and thus has a first generally conical divergent section, and a second generally conical downstream section convergent from a maximum diameter apex of the filter element and defining the filter device outlet. The housing and filter element define therebetween first and second frustoconical annular fluid flow chambers of successively diminishing cross-sectional radial thickness in the direction of downstream fluid flow.