| 摘要 |
PROBLEM TO BE SOLVED: To stratify an air-fuel mixture flowing into a cylinder so as to enlarge the lean limit of the air-fuel mixture. SOLUTION: An air assisted injector 18 is disposed at an intake pipe 2 of an engine 1, and fuel injected by the injector 18 flows into a combustion chamber 3 (into a cylinder) through an intake valve 14. At this time, the grain diameter of the fuel injected by the injector 18 is atomized to about 10-30μm. A CPU 33 in an ECU 30 controls driving of the injector 18 so that the fuel inflow quantity into the cylinder per hour is increased toward the latter period of an intake stroke. Since a large quantity of injection fuel is taken in immediately before closing of the intake valve 14, a stratified airfuel mixture is formed in the cylinder, that is, a part around a spark plug is in an air-fuel ratio atmosphere sufficient for combustion so as to make stable combustion possible even in a lean atmosphere on the whole.
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