| 摘要 |
PROBLEM TO BE SOLVED: To enhance the ignition stability of self-igniting combustion of a compressive self-ignition type internal combustion engine without increasing the quantity of NOx discharged. SOLUTION: In a self-ignition combustion range, total injection period, number of injections, and the time to start injection are set according to engine load and engine speed which indicate ignitability. Multiple injections by which fuel is periodically injected twice or more during one cycle are carried out in accordance with the total injection period, number of injections and the time to start injection to create an air-fuel mixture with irregular variations in air-fuel ratio. The air-fuel mixture with the irregular variations in air-fuel ratio is easier to ignite than if a uniform air-fuel mixture is caused to self-ignite, because combustion is started from the rich portion of the mixture. Also, the air-fuel mixture can make smaller the quantity of NOx discharged than if it is stratified.
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