| 摘要 |
PROBLEM TO BE SOLVED: To improve cleanliness of exhaust gas and fuel efficiency by calculating valve timing control amount based on advance angle amount and target advance angle amount both calculated via calculation means and thus controlling to reduce valve-overlapped amount if a combustion state immediately after an engine started is unstable. SOLUTION: When an internal combustion engine 1 is in operation, a present advance angle amount which is a phase difference between a cam angle sensor 15 and crank angle sensor 13 is calculated by an ECU 25. First and second maps with target angle amount settings based on an engine speed and charging efficiency are provided in this system. A target advance angle amount is calculated, until the elapsed time after the engine started reaches a prescribed value, by means of the second map in which a region with small target advance angle amount settings is large, rather than by means of the first map used for calculating a target advance angle amount in a normal condition. The valve timing control amount is calculated based on the present advance angle amount and target advance angle amount calculated thereby, enabling reducing valve-overlapped amount if a combustion state immediately after the engine started is unstable.
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