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.

There is presented various embodiments disclosed in this application, including an improved crankshaft system using a load connecting member which provides a greater maximum torque angle than a conventional system, thereby improving efficiency and power.

There is presented various embodiments disclosed in this application, including an improved crankshaft system using a load connecting member which provides a greater maximum torque angle than a conventional system, thereby improving efficiency and power.

An internal combustion engine, including a pair of opposed pistons, a pair of opposed cylinders, and an output shaft, wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft, wherein the coupling includes a connecting rod coupled to the opposed pistons, and the coupling further includes a crankshaft rotatably mounted within a slider bearing, the slider bearing being formed of separable parts and having unitary sides for sliding contact within the connecting rod.

An internal combustion engine, including a pair of opposed pistons, a pair of opposed cylinders, and an output shaft, wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft, wherein the coupling includes a connecting rod coupled to the opposed pistons, and the coupling further includes a crankshaft rotatably mounted within a slider bearing, the slider bearing being formed of separable parts and having unitary sides for sliding contact within the connecting rod.

An internal combustion engine, including a pair of opposed pistons, a pair of opposed cylinders, and an output shaft, wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft, wherein the coupling includes a unitary connecting rod coupled to the opposed pistons, the connecting rod having side guides for guiding a slider bearing located for reciprocating movement relative to the connecting rod, and the coupling further includes a crankshaft rotatably mounted within the slider bearing, the crankshaft having at least one guide shoulder for supporting axial location relative to the slider bearing.

An internal combustion engine, including a pair of opposed pistons, a pair of opposed cylinders, and an output shaft, wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft, wherein the coupling includes a unitary connecting rod coupled to the opposed pistons, the connecting rod having side guides for guiding a slider bearing located for reciprocating movement relative to the connecting rod, and the coupling further includes a crankshaft rotatably mounted within the slider bearing, the crankshaft having at least one guide shoulder for supporting axial location relative to the slider bearing.

An internal combustion engine, including a piston, a cylinder, and an output shaft, wherein the piston is arranged for reciprocating motion within the cylinder, driven by combustion, and the piston is coupled to the output shaft by a coupling such that said reciprocating motion of the piston drives rotation of the output shaft, wherein the engine further includes an oil pump arrangement having a multi-stage regulator.

An internal combustion engine, including a piston, a cylinder, and an output shaft, wherein the piston is arranged for reciprocating motion within the cylinder, driven by combustion, and the piston is coupled to the output shaft by a coupling such that said reciprocating motion of the piston drives rotation of the output shaft, the coupling being arranged such that the piston has sinusoidal motion when plotted against rotational angle of the output shaft.