US Patent 7819096 Cylinder valve operating system for reciprocating internal combustion engine

A cylinder valve operating system for an internal combustion engine includes a camshaft driving a number of intake and exhaust valve operators which may be selectively disabled through the operation of a valving system including a hydraulic phase shifter integrated with the camshaft and connected between a source of high pressure oil and at least the intake valve operators. The hydraulic phase shifter allows one group of valves, such as the exhaust valves, to be disabled before the other group of valves, typically the intake valves.