To stably retain the combustion condition of a compression stroke injection mode, by setting the reference ignition timing of an ignition plug on the basis of a fuel injection mode and a load correlation value, and correcting the reference ignition timing according to an operating condition, and also restricting correction when the fuel injection mode is in the compression stroke ignition mode.
When an engine 1 is operated, a target average effective pressure (load correlation value) is calculated in an ECU 70 on the basis of the output signals of a throttle opening sensor 29 and a crank angle sensor 17. Also, volumetric efficiency is calculated on the basis of the information of an intake air amount from an air flow sensor 32. Then, various combustion parameters of a target air-fuel ratio A/F, reference fuel injection finishing timing determining fuel injection timing, reference ignition timing and an EGR amount, are set according to these calculated results. Further, various combustion parameters are corrected according to an operating condition, however, at this time, when a fuel injection mode is a compression stroke injection mode, correction is restricted, and ignition timing is retained in the vicinity of the reference ignition timing, so that deterioration of combustion is prevented.
HATAYAMA KENJIROU
TAMURA HIROKI
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