Patent ID: 6499474
Filing Date: 2002-12-31
Classification: F02D,Y02T

Abstract:
An air/fuel ratio control apparatus for an internal combustion engine, said apparatus comprising:fuel injectors respectively provided on a plurality of cylinders; an air/fuel ratio sensor disposed at a collective portion of an exhaust system at which exhaust gases from the respective cylinders are collected; a crank angle sensor for detecting a crank angle phase of each of said cylinders; an air/fuel ratio detection period setting section for setting an air/fuel ratio detection period in which an exhaust stroke of each cylinder is included; a peak phase detecting section for taking in an output of said air/fuel ratio sensor during said air/fuel ratio detection period and detecting peak phases which become a maximum on a rich side or on a lean side due to variations in the air/fuel ratio; an air/fuel ratio correction cylinder determining section for specifying, based on said peak phases, an air/fuel ratio correction target cylinder for which an air/fuel ratio is to be corrected; and a cylinder-specific air/fuel ratio correcting section for correcting an amount of fuel to be supplied to said air/fuel ratio correction target cylinder; wherein the amounts of fuel to be supplied to said respective cylinders are made uniform by means of said cylinder-specific air/fuel ratio correcting section.