Patent ID: 6779512
Filing Date: 2004-08-24
Classification: F02D

Abstract:
An apparatus for controlling the air-fuel ratio of air-fuel mixture drawn into a combustion chamber of an engine, wherein an intake passage of the engine is connected to a canister, wherein the canister adsorbs fuel vapor generated in a fuel tank, wherein gas containing fuel vapor is purged as purge gas from the canister to the intake passage through a purge control device by intake negative pressure generated in the intake passage, the apparatus comprising:a sensor for detecting the air-fuel ratio of the air-fuel mixture; and a computer, wherein, according to a deviation of a detected air-fuel ratio relative to a target air-fuel ratio, the computer renews a vapor concentration value representing the concentration of fuel vapor contained in the purge gas by a predetermined renew amount at a time, wherein the computer sets the amount of fuel supplied to the combustion chamber according to the renewed vapor concentration value such that the detected air-fuel ratio seeks the target air-fuel ratio, and wherein the computer sets a smaller value of the renew amount for a greater value of the load on the engine.