| 摘要 |
PROBLEM TO BE SOLVED: To secure combustion stability of an engine in a very low load operation state such as idling while minimizing increase of pumping loss in a variable valve gear composed in such a way that lift quantity of intake valves 1 and 2 is changed in accordance with operation states of the engine by providing a lift variable mechanism in a valve system on the intake side. SOLUTION: Lift characteristics of the intake valves 1 and 2 are changed by the lift variable mechanism in such a way that so-called early closure with early valve closing timing is achieved as the lift quantity is relatively small on the lower load or lower rotation side basically. In the idling state when the lift quantity of the intake valves 1 and 2 is very small, a rotation phase of a camshaft 3 to a crankshaft is changed by a VCT 18, so that valve opening timing and valve closing timing are changed toward the delay side in such a way that the intake valves 1 and 2 have their lift peak in a crank angle period with the highest intake flow speed to a cylinder. COPYRIGHT: (C)2006,JPO&NCIPI
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