Abstract: A method and apparatus for converting thermal energy to mechanical energy. Operating on a thermodynamic cycle of isentropic compression, isothermal expansion, isentropic expansion and finally constant pressure cooling and contraction, an external heat engine utilizes a heat exchanger carrying heat from an external energy source to the working parts of the engine. Apparatus and methods are disclosed for engine piston timing, such that during isothermal expansion, each unit angular rotation of a drive shaft results in the capture of a constant, unit amount of working fluid expansion energy. Thus, the amount of energy captured during each unit angular rotation of apparatus drive shaft is a constant. Timing the working fluid expansion and fluid flow assures that the working fluid undergoes isothermal expansion, regardless of the quantum of heat energy applied. The modulation of heat input to the heat exchanger results in an automatic modulation of engine speed.

Abstract: A method and apparatus for converting thermal energy to mechanical energy which can use a wide range of fuels and perform with a high efficiency. Operating on a little utilized thermodynamic cycle of isentropic compression, isothermal expansion, isentropic expansion and finally constant pressure cooling and contraction. The external heat engine utilizes a heat exchanger carrying heat from the external energy source to the working parts of the engine. Pistons and cylinders are activated by appropriate means to adiabatically compress the working fluid, for example ambient air, to transfer the entire mass of the air through the heat exchanger to accomplish isothermal expansion followed by adiabatic expansion and, finally, exhaust the air to ambient to allow for constant pressure cooling and contraction. Valve pistons in conjunction with the cylinders form valves that allow for the exchange of working fluid with ambient.

Abstract: A method and apparatus for converting thermal energy to mechanical energy which can use a wide range of fuels and perform with a high efficiency. Operating on a little utilized thermodynamic cycle of isentropic compression, isothermal expansion, isentropic expansion and finally constant pressure cooling and contraction. The external heat engine utilizes a heat exchanger carrying heat from the external energy source to the working parts of the engine. Pistons and cylinders are activated by appropriate means to adiabatically compress the working fluid, for example ambient air, to transfer the entire mass of the air through the heat exchanger to accomplish isothermal expansion followed by adiabatic expansion and, finally, exhaust the air to ambient to allow for constant pressure cooling and contraction. Valve pistons in conjunction with the cylinders form valves that allow for the exchange of working fluid with ambient.