An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

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 opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

An opposed piston engine has a driveshaft with a first combustion cylinder parallel with a driveshaft and disposed about the driveshaft at a first radius and a second combustion cylinder parallel with the driveshaft and disposed about the driveshaft at a second radius greater than the first radius. A first pair of curvilinear shaped cams are associated with the first combustion cylinder and disposed on the driveshaft and a second pair of curvilinear shaped cams are associated with the second combustion cylinder and disposed on the driveshaft outwardly of the first pair of cams.

An internal combustion engine provides a cylinder able to rotate about a rotational axis L, a combustion chamber defined in the cylinder, and drive parts. The drive parts provides pistons housed in the cylinder able to slide in the rotational axis direction and defining a combustion chamber, slots formed in the circumferential surface of the cylinder, and followers extending from the pistons through the slots to the cams. The slots are configured to limit relative movement of the followers with the pistons to the cylinder in a circumferential direction of the rotational axis, allowing relative movement of the followers with the pistons to the cylinder in a direction of the rotational axis. Combustion performed in the combustion chamber moves the pistons with the followers along profiles of the cams to rotate the cylinder about the rotational axis, and the rotation of the cylinder is taken out as engine output.

An opposed piston engine has a driveshaft with a spaced apart cams mounted thereon. Each cam has a circumferential cam shoulder of a curvilinear shape selected to enhance flow through intake and exhaust ports. The curvilinear shape may be a segmented polynomial shape forming lobes which lobes are asymmetrical so that the lobe wavelength distance from a first trough to the lobe peak of an ascending shoulder portion of the lobe is greater than the lobe wavelength distance from the peak to a second trough of a descending shoulder portion of the lobe. Opposing cam shoulders may be shaped so as to always be converging or diverging from one another.

In an axial piston motor in which fuel and compressed combustion medium are continuously burned in a combustion chamber so as to be turned into the working fluid and successively be delivered to working cylinders, at least one of the compressor discharge valves is closed in a positively controlled manner and is opened by a compressor pressure building up in the respective compressor cylinder.

In an axial piston motor in which fuel and compressed combustion medium are continuously burned in a combustion chamber so as to be turned into the working fluid and successively be delivered to working cylinders, at least one of the compressor discharge valves is closed in a positively controlled manner and is opened by a compressor pressure building up in the respective compressor cylinder.

An opposed piston engine has a driveshaft with at least two combustion cylinders serially aligned along a center cylinder axis so as to be coaxial, where the center cylinder axis is parallel with but spaced apart from the driveshaft axis. A cam is disposed between adjacent combustion cylinders, as well as adjacent the outermost end of each combustion cylinder in order to reciprocatingly drive piston pairs disposed in each combustion cylinder.

The present invention is helical follower internal combustion engine. The present invention has a smooth, cylindrical follower orthogonally attached to a piston rod. The follower fits into two connected half-cylindrical, helical grooves formed by a two-piece cylindrical sleeve. The two-piece cylindrical sleeve is attached to a rotating cylindrical hub. Reciprocal motion of the piston causes rotation of the rotating cylindrical hub. The present invention has a feature that prevents the piston from rotating. The present invention can create electricity by connecting a rotor coil to the rotating cylindrical hub and placing a stator coil in near proximity. In an alternative embodiment, the present invention has an external drive shaft attached to the rotating cylindrical hub.