Patent ID: 6880541
Filing Date: 2005-04-19
Classification: F02D

Abstract:
1. An air-fuel ratio control apparatus for an internal combustion engine, comprising: sensor means of various types for detecting operation states of said internal combustion engine installed on a motor vehicle; an air-fuel ratio sensor for detecting an air-fuel ratio of an air-fuel mixture gas supplied to said internal combustion engine; a fuel injector for injecting a fuel contained in a fuel tank into an intake system of said internal combustion engine; a canister for adsorbing a fuel vapor from said fuel tank; a purge control valve for introducing the adsorbed fuel of said canister into said intake system of said internal combustion engine; and an engine control unit for activating said canister and driving said purge control valve on the basis of detection signals of said various sensor means and said air-fuel ratio sensor, wherein said engine control unit is comprised of: acceleration decision means for making decision as to accelerating state of said motor vehicle on the basis of said engine operation state; air-fuel ratio control means for arithmetically determining a fuel injection quantity on the basis of said engine operation state to thereby drive said fuel injector while controlling said air-fuel ratio to a desired value thereof through a feedback control on the basis of said detection signal of said air-fuel ratio sensor; purge control means for driving said purge control valve on the basis of said engine operation state; and fuel correction arithmetic means for arithmetically determining a purge air concentration correcting coefficient for correcting said fuel injection quantity on the basis of the control quantity for said purge control valve validated by said purge control means and said engine operation state, wherein said fuel correction arithmetic means is so designed as to reset said purge air concentration correcting coefficient to an initial value when said purge air concentration correcting coefficient becomes smaller than a predetermined value inclusive thereof, indicating leanness of said air-fuel mixture and when it is determined that said motor vehicle is in the accelerating state.