In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per piston per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per piston per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

The present invention is directed to a dual engine-compressor system having a crankcase enclosing a crankshaft and having engine cylinder housings and compressor cylinder housings linearly disposed on opposite sides of the crankcase. Combustion pistons are reciprocatingly disposed in the engine cylinder housings and defines alternating combustion chambers on opposite sides of the pistons. Compressor pistons are reciprocatingly disposed in the compressor housings and define alternating low and high pressure compressor chambers on opposite sides of the compressor pistons. The compressor pistons undergo a 4-cycle process to drawn in, re-distribute, and then compress fluid. The compressor cylinder and piston has a series of one-way intakes and reed valves to selectively draw or push fluid in response to movement of the compressor piston.

An internal combustion engine including at least two cylinders with parallel longitudinal axes, each cylinder including an opening and a piston capable of moving in translation inside the cylinder, the respective openings of the cylinders facing each other, the pistons being in kinematic relation with a connecting rod-crank mechanism including: a spacer connecting the pistons, suitable for maintaining a fixed spacing between the pistons, the pistons being respectively attached to the arms of the spacer, a crankshaft rotating about an axis, arranged between the openings of the cylinders and between the longitudinal axes of the cylinders, the crankshaft comprising a crank pin, a rocker rotating about the crank pin, at least one connecting rod including a first, small end, rigidly attached to the spacer and a second, big end, rigidly attached to one of the ends of the rocker.

An internal combustion engine including at least two cylinders with parallel longitudinal axes, each cylinder including an opening and a piston capable of moving in translation inside the cylinder, the respective openings of the cylinders facing each other, the pistons being in kinematic relation with a connecting rod-crank mechanism including: a spacer connecting the pistons, suitable for maintaining a fixed spacing between the pistons, the pistons being respectively attached to the arms of the spacer, a crankshaft rotating about an axis, arranged between the openings of the cylinders and between the longitudinal axes of the cylinders, the crankshaft comprising a crank pin, a rocker rotating about the crank pin, at least one connecting rod including a first, small end, rigidly attached to the spacer and a second, big end, rigidly attached to one of the ends of the rocker.

The present invention is directed to a process for operating a combustion engine having a double-sided piston in a piston cylinder, wherein every stroke of the double-sided piston is a power stroke. Every piston cylinder defines a combustion chamber on each side of the double-sided piston. The process includes igniting a fuel-air mixture in each combustion chamber on each side of double-sided piston during every compression, i.e., at about top dead center and at about bottom dead center. The process utilizes the double-sided piston to achieve two power strokes per piston for each engine cycle.

An operation system for a piston-type expander includes: a first engaging member which is fixed to an output shaft of the piston-type expander, rotates together with the output shaft, and has a first slanting surface; a second engaging member which is rotatably disposed on the output shaft, and has a second slanting surface; and a drive device which, while keeping a rotation direction of the second engaging member around the output shaft fixed, moves the second engaging member in an axial direction of the output shaft to press the second slanting surface onto the first slanting surface, converts a pressing force of the second engaging member in the axial direction into a rotational torque of the first engaging member and the output shaft at a contact surface of the first and second slanting surfaces, and causes the first engaging member to rotate together with the output shaft.

An operation system for a piston-type expander includes: a first engaging member which is fixed to an output shaft of the piston-type expander, rotates together with the output shaft, and has a first slanting surface; a second engaging member which is rotatably disposed on the output shaft, and has a second slanting surface; and a drive device which, while keeping a rotation direction of the second engaging member around the output shaft fixed, moves the second engaging member in an axial direction of the output shaft to press the second slanting surface onto the first slanting surface, converts a pressing force of the second engaging member in the axial direction into a rotational torque of the first engaging member and the output shaft at a contact surface of the first and second slanting surfaces, and causes the first engaging member to rotate together with the output shaft.

A combustion engine is disclosed having a cylinder with a piston travelling through same, coupled by means of a piston rod to a crankshaft, wherein the piston rod has: a first hub in its head for coupling with the crankshaft; a second hub in its foot substantially aligned with or parallel to the first hub in the longitudinal direction of the cylinder when the crankshaft is in the upper or lower position; and a third hub in its foot, which is offset laterally towards the front with respect to the second hub in the direction of rotation of the crankshaft; the piston being coupled with the third hub, having a guide for the travel of the piston rod coupled with the second hub, and the piston being coupled with the third hub via a link rod.