METHOD AND APPARATUS FOR CONTINUOUSLY VARIABLE DIFFERENTIAL PHASING OF ENGINE VALVE OPERATION

摘要

An internal combustion engine includes a crankshaft and first and second cam actuated intake valves. A method for operating the engine includes providing a first intake cam configured to actuate the first cam actuated intake valve, and providing a second intake cam configured to actuate the second cam actuated intake valve. The second intake cam is phase adjustable relative to the crankshaft independently of the phase of the first intake cam relative to the crankshaft. A controller is provided and configured to selectively retard the phase of the second intake cam to effect later closing of the second cam actuated intake valve sufficiently to reduce the effective compression ratio of the engine. Additionally, the first intake cam may be phase adjustable relative to the crankshaft independently of the phase of the second intake cam relative to the crankshaft and the controller may additionally be configured to selectively advance the phase of the first intake cam to effect earlier opening of the first cam actuated intake valve sufficiently to increase internal exhaust gas recirculation.