Patent ID: 7591240

Claim:
A method for providing a mixture of inlet air and exhaust gas in a cylinder of an internal combustion engine, in which fluid flow between the cylinder and a cylinder head associated therewith is controlled by one or more rotary valves accommodated in the cylinder head, the method comprising: rotating the one or more rotary valves to allow a fluid flow between the cylinder and the cylinder head in a first direction and to allow a fluid flow between the cylinder and the cylinder head in a second direction, opposite the first direction, wherein the fluid flow in the first direction and the fluid flow in the second direction are allowed during a single combustion cycle of the engine; and successively overlapping at least two openings of one of the one or more rotary valves with a flow passage in the cylinder head during rotation of the one rotary valve; wherein the fluid flows in the first direction and the second direction are respectively allowed by at least partially overlapping at least two different openings with respective flow openings in the cylinder head, the at least two openings being defined in a curved portion of the one rotary valve, which curved portion is rotationally symmetric with respect to an axis of rotation of the one rotary valve; and wherein the at least two openings are rotationally offset from one another and define different flow areas.