Donald Richard Hoggatt, 682060 Chaparral Cir, Lake Havasu City, AZ 86403

4318720, Mar 9, 1982

Jul 19, 1979

6/059076

Donald L. Hoggatt - Los Angeles CA

B01D 4600

55276

A combined muffler and engine exhaust filter comprises a fixed outer shell and an inner shell. The inner shell is formed from two concentric perforated tubes held in fixed relationship to each other. Granulated or powdered filtering material fills the space between the concentric tubes. The engine exhaust is connected to one end of the combined muffler and filter. An exhaust pipe is connected to the other end. The structure which holds the inner shell and outer shell in fixed relationship to each other also causes the engine exhaust to pass through the perforations in one tube and move in a radial direction through the filter material and through the perforations in the other tube. The length of the concentric tubes, the size and number of perforations, and the thickness of the filtering material between the concentric tubes selected to adequately filter the engine exhaust without incurring an objectionable increase in back pressure. The spacing between the inner and outer shell is selected to provide the volume necessary for the required muffling action.