PURPOSE: To realize a Carnot cycle in the form of a practical engine by converting thermal energy into potential energy first and then into kinetic energy.

CONSTITUTION: Operation of a spray pump 38 makes liquid that is cooled by a heat exchanger 39 to gush out in order to cool the gas. And the oil of a pump 31 is pressed into a cylinder 21 gradually at first by both a hydraulic cylinder 26 and a cam 50 and abruptly next by the rapid operation of a cylinder 27 so that the gas undergoes adiabatic compression. Next, the gas is moved to a cylinder 22 by the operation of a cylinder 37. And the liquid heated by both a pump 43 and a heat exchanger 44 is sprayed to heat the gas. Next the liquid is introduced into a cylinder 28 for isothermal expansion of the gas then the gas undergoes abrupt adiabatic expansion owing to a cylinder 29. This drives hydraulic pumps 32 and 33 via cams 52 and 53, and compressed oil is sent to a accumulator 34. thus created potential energy rotates a generator 36 via a hydraulic motor 35. The gas reiterates the Carnot cycle; expansion-compression-expansion.