A compact and efficient Z-twin internal combustion engine is described herein. The Z-twin internal combustion engine comprises horizontally opposed cylinder arrangement that allows for vibration cancellation. The Z-twin engine comprises a central shared cam that drives angled side valves of both the opposing cylinders, thereby greatly reducing moving parts and thus provides a significantly more efficient angled valve approach.

An internal combustion engine is provided using parts that can be produced simply and inexpensively, in which internal combustion engine the fuel is burned optimally by adjustments of compression ratio and valve control times and thus the least possible harmful exhaust gases are emitted while maximum effective power is achieved. Furthermore, all liquid and gaseous fuels can be used.

An internal combustion engine has at least one piston which performs stroke movements in a cylinder crankcase. Via two connecting rods, the piston interacts with two parallel crankshafts which rotate synchronously in opposite directions. The connecting rods have, on a side facing toward a piston crown of the piston, bearing eyelets which, via piston pins, are operatively connected to the first and second bearings provided at opposite first and second sides of the piston, which bearings and piston pins act as a device for compensating an asymmetry of the profile of the crankshafts. To optimize the internal combustion engine, the first and the second bearings have cylindrical bearing disks which, firstly, are rotatably mounted in piston bores and which, secondly, include disk bores for receiving first and second pin sections of the piston pins.

An opposed piston engine includes a cylinder having a cylinder wall, and a pair of opposed pistons, Each face of each piston of the pair of opposed pistons has a top plane and a recess formed therein, each recess comprising a first surface defining part of a cone, the cone defined by the first surface of at least one of the recesses having a longitudinal axis that defines an angle equal to at least one half of a cone angle of the cone with the top plane.

A Rankine Expander System that converts low quality heat (heat usually at temperatures below 400 degrees Celsius) to electricity by using the properties of trans-critical CO.sub.2. The system is comprised of a compressor, an expander, three heat exchangers, and a permanent magnet alternator (PMA). It operates at pressures and temperatures that hold the CO.sub.2 above its critical point for the full cycle, and as such, attains high efficiencies even at low power. Under some conditions the efficiency can exceed 50%.

A combustible fluid-operated orbital engine having sets of cooperating cylinder and piston members with respective parallel axes of rotation. Respective cylinder and piston carrier wheels with respective axes of rotation parallel to the piston/cylinder axes of rotation carrying the pistons/cylinders orbitally and at all times in opposed relation on a common longitudinal axis along intersecting counter paths. Redundant belts/sprockets supported by the cylinder and piston carrier wheels rotate the pistons/cylinders counter to their circular motion direction to maintain their opposed relation for their periodic interfittment when their respective paths intersect. A combustible fluid supply is provided to the cylinder member for combustion coincident with the periodic interfittment. An air supply is provided to the cylinder member for purging exhaust gases and/or supercharging combustion gases. A sealing system that includes a non-metallic flexible seal is located either proximate the entry of each cylinder or proximate an end portion of each piston.

An internal combustion engine with two arced cylinders, with movement of the pistons in first and second cylinders takes place in the same direction. An arcing connecting rod on each of the sides of the pistons are averted from the combustion chambers. A freewheel is associated with each cylinder. An axis of the shaft represents the center of the arced shape of the cylinders and connecting rods. A side of the connecting rod opposite the piston connects to the outer side of a freewheel, and inner sides of the freewheels each connect to the shaft. Movement produced by the combustion is transmitted by the connecting rod to the outer side of the freewheel and the shaft. Outer sides of the freewheels are coupled to move in opposite directions, so the pistons in the first and the second cylinder run oppositely. A method operates such an internal combustion engine.