| 摘要 |
A fuel injection amount control apparatus (control apparatus) according to the present invention comprises an air-fuel ratio sensor 67 which is disposed between the exhaust gas merging portion HK and the upstream catalyst 53. The control apparatus performs a feedback correction on an amount of fuel (instructed fuel injection amount) to be injected by the fuel injection valve 39 in such a manner that an air-fuel ratio (detected air-fuel ratio abyfs) represented by the output value of the upstream air-fuel ratio sensor becomes equal to a target air-fuel ratio which is set at stoichiometric air-fuel ratio. Further, the control apparatus obtains an air-fuel ratio imbalance indicating value, which becomes larger as a difference in air-fuel ratio of each of the mixtures supplied to each of the combustion chambers among the cylinders becomes larger, and performs an increasing correction to the instructed fuel injection amount in such a manner that an "air-fuel ratio (instructed air-fuel ratio) determined by the instructed fuel injection amount" becomes a "richer air-fuel ratio" than the stoichiometric air-fuel ratio as the obtained air-fuel ratio imbalance indicating value becomes larger. |
