Various embodiments are described herein for methods and devices that relate to a drive mechanism that can be used in an external heat engine to control the motion of the pistons and obtain increased engine power and/or efficiency. Through control of the piston motion a non-sinusoidal piston motion can be generated which can improve engine performance by enabling an engine to more closely follow an ideal thermodynamic cycle.

The present invention refers to the technical field of thermodynamic engines, and more specifically to a heat engine that operates with gas in closed loop in differential configuration which is characterized by performing a thermodynamic cycle eight transformations or otherwise explain, it performs two thermodynamic cycles simultaneously, each with four interdependent, additional transformations, two of these transformations isothermal and two adiabatic in mass transfer in phases of adiabatic processing to provide a new performance curve no longer dependent solely on temperature but the mass transfer rate which allows the construction of machines with high yields and low thermal differentials.