US Patent 7201140 Increased engine braking with adjustable valve timing

A system and method for operating at least an intake and exhaust valve in a cylinder with a piston of an engine in a vehicle are described. In one aspect, the method comprises maintaining at least one of the intake and exhaust valves in a closed position during a period. Further, during said period where said at least one valve is in said closed position, the method may also include opening the other of the intake and exhaust valve, then closing the other of the intake and exhaust valve, and then opening the other of the intake and exhaust valve.