| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device capable of accurately controlling the air-fuel ratio of an air-fuel mixture in the desired ratio, in an internal combustion engine having a lift quantity change mechanism. SOLUTION: When a feedback control execution condition is realized, a steady separation quantity of a feedback correction quantity and its reference value is respectively separately learnt as a separation quantity learning value, when being a large lift area including an upper limit lift quantity used when the execution condition is not realized and when being a lower limit lift quantity used only when the execution condition is realized. A separation quantity correction value is determined based on a lift quantity VL and the separation quantity leaning value, and a fuel injection quantity command value is increasingly-decreasingly corrected by the separation quantity correction value. When there is no history of completing learning of the separation quantity when being the large lift area (S301:NO), transfer to a lift quantity area from the large lift area is prohibited, and change control of the lift quantity VL is executed in a range of not transferring to an area except for the large lift area (S302-S304). COPYRIGHT: (C)2009,JPO&INPIT
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