To continuously carry out combustion and exhaust of a power engine, to reduce vibration and noise comparatively small, to improve heat efficiency and to reduce generation of a harmful matter.

A compressor 1 and an expander 2 are connected to each other through a heater 3. The expander 2 is provided with a distributor 11 to change inflow of gas to the expander 2 in stages on its inlet port 9a. A pressure detector 13 is provided in a pressure regulating chamber 7 communicated to a compression chamber 1a. The distributor 11 opens valves 11a, 11b to increase a suction air flow rate to the expander 2 when the pressure detector 13 detects specified pressure, and it is controlled by a controller 15 so as to increase inflow of gas to an expansion chamber in stages. The heater 3 is connected to the pressure regulating chamber 7 through a regulating valve 14. The regulating valve 14 throttles an air flow by being interlocked with a brake and increases pressure in the compression chamber 1a. A supplementary valve 9d to prevent suction air shortage is provided at a position in front of a discharge port 9b of a casing 9.