Patent ID: 6708681
Filing Date: 2004-03-23
Classification: F02D

Abstract:
A device for feedback controlling an air-fuel ratio of an internal combustion engine comprising:an air-fuel ratio sensor installed in an exhaust pipe of said engine; a cylinder air-fuel ratio estimation unit for estimating an air-fuel ratio of an air-fuel mixture formed inside a cylinder of said engine; an air-fuel ratio detection value estimation unit for estimating an air-fuel ratio detected by said air-fuel ratio sensor, based on the cylinder air-fuel ratio estimated by said cylinder air-fuel ratio estimation unit; a cylinder air-fuel ratio correction unit for correcting the cylinder air-fuel ratio estimated by said cylinder air-fuel ratio estimation unit, based on the air-fuel ratio estimated by said air-fuel ratio detection value estimation unit and the air-fuel ratio detected by said air-fuel ratio sensor; an air-fuel ratio correction value computation unit for computing an air-fuel ratio correction value for correcting a fuel injection quantity based on the cylinder air-fuel ratio corrected by said cylinder air-fuel ratio correction unit; and a fuel injection quantity computation unit for computing a fuel injection quantity based on the air-fuel ratio correction value computed by said air-fuel ratio correction value computation unit.