| 摘要 |
PROBLEM TO BE SOLVED: To optimize injection start time of pilot injection and improve the ignition property when a diesel engine is started at a low temperature. SOLUTION: A small amount of fuel is injected as pilot injection prior to main injection in accordance with an operation condition of the engine. Although gas temperature in a cylinder rises in accordance with a crank angle in a compression process, the gas temperature in the cylinder is reduced on the whole if, for example, the number of cranking revolutions is small. Crank angles (CAA, CAB) at which the gas temperature in the cylinder reaches a predetermined temperature Th are calculated based on a suction air temperature, and the time when the gas temperature in the cylinder exceeds the predetermined temperature Th is set as injection start time of pilot injection. By setting the predetermined temperature Th close to a low temperature oxidation reaction start temperature of fuel, the injected fuel is securely ignited and satisfactory ignition property and low temperature start property are obtained.
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