Air-fuel ratio control device of an internal combustion engine

摘要

An air-fuel ratio control device comprising an electric air bleed control valve which controls the amount of air fed into the fuel passage of the carburetor so that an air-fuel ratio becomes equal to the stoichiometric air-fuel ratio. The degree of opening of the air bleed control valve is increased as an electric current fed into the air bleed control valve is increased. Fuel vapor is fed into the intake passage from the canister. An auxiliary air is also fed into the intake passage via an electric auxiliary air bleed control valve. When the supply of fuel vapor to the intake passage is started, if the electric current fed into the air bleed control valve increases and reaches the upper limit, the auxiliary air bleed control valve is opened. As a result, the electric current fed into the air bleed control valve is lowered and can move up and down so that an air-fuel ratio becomes equal to the stoichiometric air-fuel ratio.