Air-fuel ratio feedback control apparatus and method of internal combustion engine

摘要

A non-linear term UNL is computed as UNL=gain GNLx(air-fuel ratio detection value-target air-fuel ratio)/(|air-fuel ratio detection value-target air-fuel ratio|)+previous value UNL (OLD), and a linear term UL is computed as UL=gain GLx(air-fuel ratio detection value-target air-fuel ratio)/air-fuel ratio detection value. An addition of UNL and UL is set as an air-fuel ratio feedback correction coefficient to correct a fuel injection quantity. The gain GL is set a greater value as |air-fuel ratio detection value-target air-fuel ratio| becomes greater.