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 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.

A closed cycle engine power structure and a power generation method, includes a cylinder block and an inner shell. The inner shell is located at the cylinder block, and the inner enclosed cavity of the cylinder block is divided into an outer duct and an inner duct, and an electric coil is arranged in the inner shell. An Archimedes pump is arranged in the inner duct, the electric coil is in drive connection with the Archimedes pump to form a motor structure. Tension structures are arranged in the outer duct. The Archimedes pump is driven to rotate to form a pressure difference between the top and bottom of the cylinder block, generating airflow around the tension structures. According to Bernoulli principle, the pulling force is generated by tension structures. The tension structures concentrate on the cylinder block to form the power of the engine power structure.

A closed cycle engine power structure and a power generation method, includes a cylinder block and an inner shell. The inner shell is located at the cylinder block, and the inner enclosed cavity of the cylinder block is divided into an outer duct and an inner duct, and an electric coil is arranged in the inner shell. An Archimedes pump is arranged in the inner duct, the electric coil is in drive connection with the Archimedes pump to form a motor structure. Tension structures are arranged in the outer duct. The Archimedes pump is driven to rotate to form a pressure difference between the top and bottom of the cylinder block, generating airflow around the tension structures. According to Bernoulli principle, the pulling force is generated by tension structures. The tension structures concentrate on the cylinder block to form the power of the engine power structure.

An attitude-supporting apparatus of a wearable robot includes an actuator for generating a hydraulic pressure by a worker's direct manipulation, and a driving unit including, the driving unit including: an inner component and an outer component capable of relatively rotating, and control components for controlling the relative rotations of the inner component and the outer component, wherein a motion of the control components is controlled by receiving the hydraulic pressure generated from the actuator.

An attitude-supporting apparatus of a wearable robot includes an actuator for generating a hydraulic pressure by a worker's direct manipulation, and a driving unit including, the driving unit including: an inner component and an outer component capable of relatively rotating, and control components for controlling the relative rotations of the inner component and the outer component, wherein a motion of the control components is controlled by receiving the hydraulic pressure generated from the actuator.

A sliding component and its producing method are provided. The sliding component includes a base section made of steel or cast iron, and a sliding section having a sliding surface, made of copper alloy including hard particles, and joined to the base section. The hard particles in the sliding section are arranged such that those in a region including an outer periphery of the interface with the base section have their longitudinal directions coinciding with the directions along the outer periphery as compared to those in an inner peripheral side. This improves the durability of the sliding section in its region including the outer periphery of the interface with the base section.

A sliding component and its producing method are provided. The sliding component includes a base section made of steel or cast iron, and a sliding section having a sliding surface, made of copper alloy including hard particles, and joined to the base section. The hard particles in the sliding section are arranged such that those in a region including an outer periphery of the interface with the base section have their longitudinal directions coinciding with the directions along the outer periphery as compared to those in an inner peripheral side. This improves the durability of the sliding section in its region including the outer periphery of the interface with the base section.