| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device of an internal combustion engine capable of preventing an emission from being deteriorated owing to the deviation in the output value of a downstream side sensor to detect the air-fuel ratio state at the downstream side of an exhaust gas purifying catalyst. SOLUTION: When the output value of an oxygen sensor is deviated to the lean side than the output value equivalent to a theoretical air-fuel ratio, it is judged that a lean stack abnormal occurs in the oxygen sensor (S100). When it is judged that the lean stack abnormal occurs in the oxygen sensor, an upper limit guard value Gmax to restrict the maximum value of a sub feedback correction amount SFB is changed into a smaller value (S110). On the other hand, when the output value of the oxygen sensor is deviated to the rich side than the output value equivalent to the theoretical air-fuel ratio, it is judged that the rich stack abnormal occurs in the oxygen sensor (S120). When it is judged that the rich stack abnormal occurs in the oxygen sensor, a lower limit guard Gmin to restrict the minimum value of a sub feedback correction value SFB is changed into a larger value (S130). COPYRIGHT: (C)2006,JPO&NCIPI
|
