| 摘要 |
PROBLEM TO BE SOLVED: To effectively reduce a hydrocarbon discharge quantity of an engine. SOLUTION: On starting the engine or immediately after starting the engine, when it is not yet in an intake pipe pressure drop state (a state in which the intake pipe pressure is lower than a predetermined pressureα), as a retraction effect of unburnt hydrocarbon due to descent of a piston after a top dead center is little, an unburnt hydrocarbon discharge quantity is decreased by trapping the unburnt hydrocarbon in a cylinder by executing an exhaust valve early closing control for advancing an angle of an exhaust valve timing and controlling a closing timing of the exhaust valve to be prior to the top dead center. Then, when the intake pipe pressure drops to be lower than the predetermined pressureαbringing about the intake pipe pressure lowering state, the retraction effect of the unburnt hydrocarbon increases due to descent of the piston after the top dead center and the unburnt hydrocarbon once discharged from the cylinder in an exhaust process is effectively retracted by descent of the piston after top dead center as an exhaust valve late closing control for controlling the closing timing of the exhaust valve after the top dead center is executed by delaying an angle of the exhaust valve timing. COPYRIGHT: (C)2009,JPO&INPIT
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