Gas seal means for rotary piston engines

Rotary piston engine including a casing which is comprised of a rotor housing having an inner wall surface of trochoidal configuration and a pair of side housings respectively having inner surfaces and secured to the opposite sides of the rotor housing, a substantially polygonal rotor disposed in said casing for rotation with apex portions in sliding contact with the inner wall surface of the rotor housing, said rotor having opposite side surfaces respectively confronting with the inner surfaces of the side housings and provided at radially central portions thereof with axially projecting lands adapted to engage slidably with the inner surfaces of the side housings to maintain clearances between the rotor side surfaces and the inner surfaces of the side housings radially outwardly of said lands, said rotor further having flanks defined between respective two of the apex portions and confronting to the inner wall surface of the rotor housing, side seal means provided on each side surface of the rotor and extending substantially along the flanks of the rotor at portions radially inwardly of the flanks to leave circumferential areas on each of the rotor side surfaces between the flanks and the side seal means, and filler means comprised of a fluoride resin and applied to each of the rotor side surfaces at areas at least radially outwardly of said side seal means for substantially filling said clearance between the rotor side surfaces and the inner surfaces of the side housings in said areas.