Abstract: A rotary valve, having a cylindrical rotor mounted within a cylindrical bore in a casing with a predetermined clearance defined between the cylindrical surface of the rotor and the cylindrical edge surface of the bore, a first seal sealing posible leaks of a gas from a selectively fluidly connecting arrangement in the rotor in the axial direction of the rotor, and a second means seal sealing possible leaks of the gas from the connecting arrangement in the radial direction of the rotor. The casing has part of the first and second seals which is attached thereto. A combination of the clearance and the first and second seals enables the rotor to rotate with a low friction.

Abstract: A rotary piston type internal combustion engine comprising a casing which includes a rotor housing having cavity defined by a trochoidal inner peripheral wall having a major and a minor axes, and a pair of side housings sealingly secured to the opposite sides of the rotor housing, a substantially polygonal rotor disposed in said cavity for rotation with apices in sliding contact with the inner peripheral wall of the rotor housing to define working chambers of variable volume with the trochoidal inner peripheral wall of the casing, said casing having an air intake port and an exhaust port, a primary combustion chamber disposed outside the cavity in the casing, a communication passage connecting the primary combustion chamber with the cavity in the casing, a fuel injection nozzle provided in said primary combustion chamber, and an ignition plug provided in said primary combustion chamber, said primary combustion chamber having a volume which is 35 to 65 percent of the sum of volume of the primary combustion cha