Abstract: A thermodynamic cycle heat engine including a regenerator; a chamber in fluid communication with the regenerator; first and second rotors within the chamber, forming at least a pair of spaces within the chamber; and at least one actuator. The regenerator and the chamber form a portion of a closed space for a working fluid, the actuator is arranged to displace the rotors about an axis of rotation for the rotors, and at least a portion of the actuator is fixedly secured to the rotors. In some aspects, the actuator is arranged to receive energy from the rotors and operate as a generator, or a sensor is arranged to detect a condition associated with operation of the chamber and a controller is arranged to control the actuator responsive to the detected condition. In some aspects, the engine includes a heat exchanger in fluid communication between the regenerator and the chamber.

Abstract: A thermodynamic cycle heat engine comprising a regenerator housing with two bi-directional regenerators, compression and expansion chambers connected to different ends of the housing, and a gear train. Each of the bi-directional regenerators comprises a low pressure connection having a first volume and a high pressure connection having a second volume less than the first volume. The bi-directional regenerators, the compression chamber, and the expansion chamber form a closed space for a working fluid. The gear train is disposed within the regenerator housing and comprises a plurality of non-round gears, a center gear group, and two outer gear groups substantially opposed with respect to the center gear group. The gear train oscillatingly rotates rotors in the chambers to create cyclically varying volumes for compression and expansion spaces so that two thermodynamic cycles are completed by the engine for each rotation of the rotors.