AIR-FUEL RATIO CONTROLLER FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To allow an engine operation air-fuel ratio to easily and accurately maintain a target air-fuel ratio by excluding the influence on the engine air-fuel ratio by purge. SOLUTION: An engine fuel injection amount in purging the evaporated fuel is corrected on the basis of the output of an intake oxygen concentration sensor 31 mounted on an intake passage of an internal combustion engine 1. An electronic control unit(ECU) 30 controlling the engine determines a sensor output ratioαas a ratio of the output of the intake oxygen concentration sensor in purging, and the output of the intake oxygen concentration sensor under the same intake pressure in stopping the purge, and calculatesλas a ratio of the target air-fuel ratio and a stoichiometric air-fuel ratio. The ECU further reduces and corrects the engine fuel injection amount in purging to (1-(1-α)×λ) times by usingαandλ. Whereby the engine air-fuel ratio can maintain the target air-fuel ratio regardless of the mixture of the vapor into the intake by purging.