Abstract: Valve assembly and method in which a valve member is connected to an elongated lever arm for controlling communication between two chambers in an internal combustion engine. The valve assembly is disposed at least partially within one of the chambers, and the valve member is moved between open and closed by an actuator connected to the lever arm. In some disclosed embodiments, a pilot valve is opened to equalize pressure on both sides of the valve member prior to moving the valve member toward the open position. In others, where a piston in an expansion cylinder is driven by hot, expanding gases from a separate combustion chamber, the exhaust valve is closed before the piston has completed its exhaust stroke, and pressure is allowed to build up in the expansion cylinder to a level corresponding to the pressure in the combustion chamber before the valve member is moved toward the open position.

Abstract: A method includes operating an internal combustion engine according to a four-stroke combustion cycle. The four-stroke combustion cycle includes a combustion stroke, an exhaust stroke, an intake stroke and a compression stroke. A valve associated with a cylinder of the internal combustion engine is opened at a first time during the four-stroke combustion cycle. The valve is closed at a second time during the four-stroke combustion cycle. The valve is opened at a third time during the four-stroke combustion cycle. The valve is closed at a fourth time during the four-stroke combustion cycle.

Abstract: An internal combustion engine includes slidable valves. Horizontal valve seats of tapered design are associated with inlet and exhaust ports at the top of the engine's combustion chambers. The slidable valves are generally planar and tapered to conform to the valve seats. A rod is engaged to the rear of each valve and is spring-loaded. Movement of the slidable valves is effected through mechanical coupling of the rotation of the crankshaft to a rocker arm that is oriented substantially orthogonal to the rod whereby crankshaft rotation is translated into horizontal, sliding movements of the planar valves.