US Patent 7805934 Displacer motion control within air engines

Methods and apparatus are disclosed for generating power. A thermodynamic air engine is configured to convert heat provided in the form of a temperature differential to mechanical energy. The thermodynamic air engine has a working fluid and a displacer adapted to move through the working fluid. The temperature differential is established across the thermodynamic air engine between a first side of the engine and a second side of the engine. The displacer is directly actuated to move the displacer cyclically through the working fluid in accordance with a defined motion pattern.