Patent ID: 6367459
Filing Date: 2002-04-09
Classification: F02D,F02M

Abstract:
An air-fuel ratio variation limiting apparatus for an internal combustion engine, the apparatus being equipped with an evaporation fuel processing mechanism for supplying fuel vapor in a fuel tank to a canister via a vapor passage and for purging fuel in the canister to an air-intake passage of the internal combustion engine via a purge passage provided with a purge control valve when the internal combustion engine is operated, the apparatus supplying the fuel vapor in the fuel tank during refueling to the canister via a breather passage provided with a pressure sensitive valve that opens in response to a variation in pressure in the fuel tank during refueling, the apparatus comprising:determination means for determining whether the pressure sensitive valve is open at times other than refueling; and limiting means for limiting variation in the air-fuel ratio when the determination means determines that the pressure sensitive valve is open.