Patent ID: 6477458
Filing Date: 2002-11-05
Classification: F01N,F02D,Y02T

Abstract:
An apparatus for controlling the air-fuel ratio of an internal combustion engine, comprising:an exhaust gas sensor for detecting the concentration of a particular component in an exhaust gas purified by a catalytic converter which is disposed in an exhaust passage of the internal combustion engine, said exhaust gas sensor being disposed downstream of said catalytic converter; identifying means for identifying the values of parameters of a nonlinear function representing correlating characteristics of the detected concentration of the particular component with respect to an air-fuel ratio of the particular component upstream of said catalytic converter, using data representing the air-fuel ratio of the exhaust gas upstream of said catalytic converter and output data of said exhaust gas sensor; target air-fuel ratio calculating means for determining the value of an air-fuel ratio at which the concentration of the particular component that is represented by a function value of said nonlinear function whose parameters are identified by said identifying means is of a value satisfying a predetermined condition, using the identified values of the parameters of said nonlinear function, and obtaining the determined value of the air-fuel ratio as a target air-fuel ratio for the exhaust gas upstream of said catalytic converter; and air-fuel ratio manipulating means for manipulating the air-fuel ratio of an air-fuel mixture combusted by said internal combustion engine depending on the target air-fuel ratio determined by said target air-fuel ratio calculating means.