| 摘要 |
PROBLEM TO BE SOLVED: To properly correct an air-fuel ratio detection timing (sample timing of output from air-fuel ratio sensor) so that the air-fuel ratio of each cylinder can be accurately estimated based on the values detected by an air-fuel ratio sensor installed at the exhaust manifold part of an internal combustion engine. SOLUTION: When the air-fuel ratio is stoichiometric air-fuel ratio (theoretical air-fuel ratio), the deviation of the air-fuel ratio from the appropriate value of an air-fuel ratio detection timing is zero. When the air-fuel ratio is lean, it is deviated in the direction that the appropriate value of the air-fuel ratio detection timing is retarded (response of the air-fuel ratio sensor becomes slow). When the air-fuel ratio is rich, it is deviated in the direction that the appropriate value of the air-fuel ratio detection timing is advanced (response of the air-fuel ratio sensor becomes fast). With these characteristics taken into consideration, when a target air-fuel ratio is lean, the air-fuel ratio detection timing is corrected to be slower than when it is stoichiometric air-fuel ratio. When the target air-fuel ratio is rich, the air-fuel ratio detection timing is corrected to be faster than when it is stoichiometric air-fuel ratio. COPYRIGHT: (C)2007,JPO&INPIT
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