| 摘要 |
PROBLEM TO BE SOLVED: To rapidly quantify a relation between a combustion state and an air-fuel ratio and in turn, to improve control accuracy of an air-fuel ratio. SOLUTION: A CPU 31 in an ECU 30 performs F/B control of an air-fuel ratio, based on the output of an A/F sensor 20 disposed in the exhaust pipe 16 of an engine 10. The CPU 31 controls a combustion roughness value as a parameter, indicating the combustion state of an internal combustion engine, during a given period in a region equivalent to the lean region of an air-fuel ratio and calculates a representative value of an air-fuel ratio during the period, based on the detecting value (an actual air-fuel ratio) of the A/F sensor 20. After the CPU 31 learns the fundamental data on a target air-fuel ratio based on the representative value of the calculated air-fuel ratio after control of a combustion state for a given period is completed, and the learned value is stored at a backup RAM 34.
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