Patent Document ID: 20080040018
Application ID: 11819652
Patent Flag: 0

Claim One:
1. A cylinder air-fuel ratio controller for an internal combustion engine comprising: an estimation means for estimating an air-fuel ratio of each cylinder based on a detection value of an air-fuel ratio sensor disposed in an exhaust confluent portion into which an exhaust gas from a plurality of cylinder of the internal combustion engine flows, the air-fuel ratio sensor detecting an air-fuel ratio of the exhaust gas; a computation means for computing a cylinder air-fuel ratio correction quantity of each cylinder for correcting a variation in an air-fuel ratio between the plurality of cylinders for each cylinder; a learning means for learning the cylinder air-fuel ratio correction quantity; a control means for performing cylinder air-fuel ratio control for correcting a fuel injection quantity of each cylinder on the basis of the cylinder air-fuel ratio correction quantity and/or its learning value to reduce the variation in the air-fuel ratio between the cylinders; and a prohibition means for prohibiting the learning means from learning the cylinder air-fuel ratio correction quantity when the cylinder air-fuel ratio correction quantity of any cylinder is outside a specified range.