Patent ID: 6513321
Filing Date: 2003-02-04
Classification: F01N,F02D,Y02T

Abstract:
An exhaust gas purifying apparatus for an internal combustion engine having an exhaust system, comprising:a plurality of catalysts; a first detection unit, disposed in the upstream of said catalysts, which detects the concentration of a predetermined substance; a second detection unit, disposed in the downstream of said catalysts, which detects the concentration of a predetermined substance; a target air-fuel ratio setting unit, sets a target air-fuel ratio of a mixture to be supplied to the engine; a feedback control unit which controls an air-fuel ratio of an air-fuel mixture to be supplied to said engine to said target air-fuel ratio in a feedback manner responsive to the output of said first detection unit; and a first target air-fuel ratio correction unit which corrects said target air-fuel ratio responsive to the output of the second detection unit only when the output of the second detection unit exceeds a predetermined value and when the output of the second detection unit is less than the predetermined value, the target air-fuel ratio set by said target air-fuel ratio setting means is used in the feedback control.