Patent Document ID: 5465703
Application ID: 08079909
Patent Flag: 1

Claim One:
1. A method for controlling canister purge of an internal combustion engine having a purge control system for purging fuel vapor vaporized in a fuel tank into the engine, an air-fuel feedback control system having an O.sub.2 sensor for controlling a fuel injection amount at a desired value according to a basic fuel injection amount based on detected engine operating conditions and an air-fuel ratio correcting coefficient based on a signal from said O.sub.2 sensor, the method comprising: changing an amount of purging fuel during a predetermined period; calculating a variation of said air fuel-ratio correcting coefficient corresponding to said changing of purging fuel; assuming a canister loading rate according to said variation of said air-fuel ratio correcting coefficient; determining the purge amount of fuel vapor based on said assumed canister loading rate; and controlling a canister purge according to said assumed canister loading rate.