Abstract: An external combustion rotary engine includes a piston arranged to travel around a toroidal chamber in an engine block. Intake and exhaust ports extend into the chamber at radially separated positions. A gate hinged at a top edge extend across the chamber between the intake and exhaust ports. A driveshaft is aligned with the center of the toroidal chamber, and a tubular cam is coaxially and slidably positioned on the driveshaft within the engine block. The cam includes a protruding cam surface with a spiral leading edge. The piston is attached to the edge of a disc concentric with and attached to the driveshaft. The cam is slidable along the driveshaft for advancing or retracting the spiral leading edge from an intake valve for varying the timing thereof. When the valve is opened, the piston is pushed around the chamber by a pressurized gas introduced through the intake port. Exhaust gas is pushed ahead of the piston through the exhaust port. The gate is opened when struck by the piston.

Abstract: An engine comprises at least one cylinder and preferably several cylinders side-by-side. Each cylinder comprises a toroidal cylinder and has a piston which revolves around the cylinder. The piston is fixed to the periphery of a disk fixed to the main shaft which coincides with the axis of the cylinder. At one position of the cylinder a gate is installed which seals the cylinder into two sections. On one side of the gate is an inlet port and on the opposite side an exhaust port. A valve controlled by a cam shaft timed from the main shaft controls the inlet port. A gaseous medium is externally heated in a heater and is introduced under pressure through the inlet port and drives the piston around the cylinder; the medium in the cylinder ahead of the piston from the previous cycle is discharged through the exhaust port and cooled and then reheated. The valve is manually (or pedally) controlled to cut off to maintain proper speed for the load on the main shaft.