Abstract: A rotary piston engine comprising two segregated body chambers of compression and expansion, and one separable combustion chamber, carrying out air suction and compression, combustion resultant expansion and exhaust, and fuel injection and constant-volume combustion process without any valve respectively: the compression and the expansion chamber both are arranged parallel adjacent to each other, both are formed by two partially overlapped body-bores provided respectively with cylindrical hubs at respective centers thereof, both have a pair of screwed rotors rotatably mounted on said respective hubs, and both communicate to each other by the combustion chamber and gas passageway means; it is characteristic in configuration that the closed space made by rotor projecting portions are progressively changed in geometry as rotors rotate, and that exhaust gases make no explosion noises.

Abstract: A rotary combustion engine has two segregated chambers which communicate with each other via passageways. Combustion occurs in the first chamber and expansion occurs in the second chamber. Each chamber includes two sidewise abutting cylinder lobes with a piston-like rotor and a cylindrical hub being rotatably mounted in each cylinder lobe. Compressed gas is ignited in the first chamber in a constant volume, the ignited gas then flows into the second chamber, where it expands, and thereafter the expanded gas is discharged under constant pressure.

Abstract: A rotary engine having combustion and expansion chambers provided respectively with a pair of cylindrical hubs, each chamber having a pair of pistonlike rotors with a configuration making it possible that any one of the combustion pockets continues to close during about a half turn of the rotor and also making the deadspace smaller than that of any other known rotor. This allows both burning of all fuels at a high compression ratio under a constant volume at slow speed and discharging of most of the exhaust gases expanded to 1 atm without mixing with high pressure burnt gases for the following expansion process. Consequently the engine is operated in the CVC/CPX cycle, which has a higher thermal efficiency than any other cycle in internal combustion engines operating at the same compression ratio.