Air-fuel ratio control device of an internal combustion engine
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsKouji Uranishi, Takaaki Itou
Life of this patent
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Abstract
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. When the electric current fed into the air bleed control valve is increased and reaches a predetermined upper limit due to the supply of purge gas, the current fed into the air bleed control valve is instantaneously increased by a fixed amount.
Claims23
An internal combustion engine having at least one cylinder, an intake passage and an exhaust passage, said engine comprising:
- a charcoal canister containing activated carbon therein and connected to the intake passage via a purge passage;
- fuel supply means arranged in the intake passage to feed fuel into the intake passage;
- an oxygen concentration detector arranged in the exhaust passage to produce a lean signal when an air-fuel ratio of an air-fuel mixture fed into the cylinder is larger than a predetermined air-fuel ratio and to produce a rich signal when said air-fuel ratio of the air-fuel mixture is smaller than the predetermined air-fuel ratio;
- first means producing an electric correction signal for correcting the amount of fuel fed from said fuel supply means in response to said lean signal and said rich signal to equalize said air-fuel ratio of said air-fuel mixture with the predetermined air-fuel ratio, said electric correction signal having a level which normally varies between a predetermined upper limit and a predetermined lower limit and reaches either one of said predetermined upper limit and said predetermined lower limit when the air-fuel mixture fed into the cylinder becomes excessively rich;
- determining means for determining whether or not the level of said electric correction signal reaches either one of said predetermined upper limit and said predetermined lower limit;
- and
- second control means operated on the basis of a determination by said determining means to increase the air-fuel ratio of the air-fuel mixture fed into the cylinder until said air-fuel ratio becomes approximately equal to the predetermined air-fuel ratio when the level of said electric correction signal reaches either one of said predetermined upper limit and said predetermined lower limit.
Dependencies are inferred from the claim text.