| 摘要 |
PROBLEM TO BE SOLVED: To control a fuel amount remaining in a cylinder to a proper value even if fuel is returned into a suction system from the cylinder when a suction valve is controlled so as to close during a compression process. SOLUTION: An engine control circuit 21 delays valve closing timing of the suction valve 13 up to the compression process to reduce pumping loss and improve fuel consumption. At this time, the engine control circuit 21 calculates a fuel return rate (a ratio of fuel amount returned into the suction system from the cylinder during the compression process for a total fuel amount sucked into the cylinder in a suction process) based on the valve closing timing of the suction valve 13, calculates a demand fuel amount in accordance with an engine operation condition, and calculates a fuel injection amount using the fuel return rate so that fuel amount remaining in the cylinder agrees with the demand fuel amount. When the fuel return rate is calculated, the compensation may be done so that the fuel return rate increases as a cylinder temperature or a cooling water temperature which is its substitute information increases.
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