| 摘要 |
PROBLEM TO BE SOLVED: To minimize transient HC emission deterioration due to wall flow on an intake port wall surface in a period from cold start to warming-up completion of an engine. SOLUTION: Since this engine is a type injecting fuel to an intake port and is equipped with hydraulic drive variable valve gears, valve overlap is set to the minimum (-6°CA) at the time of start during which hydraulic pressure is low. An injection completion timing IT is delayed right after the engine starts at a time T0, and intake stroke injection is continued until a time T1. After drive of the variable valve gears 5, 6 is permitted at the time T1, the injection completion timing is controlled to a prescribed injection completion timing IT at which HC emission becomes the minimum under each intake valve open timing, corresponding to a sequentially changing intake valve open timing IVO. Thereby, the intake valve open timing IVO is advanced while keeping HC emission at the minimum, and overlap becomes 14°CA. After that, retardation of the injection completion timing is completed at a time T2 based on the cooling water temperature Tw, and the injection completion timing is returned to a standard injection completion timing IT0. The variable valve gears 5, 6 are shifted to normal control at a time T3 to reduce overlap. COPYRIGHT: (C)2010,JPO&INPIT
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