Power plants – Internal combustion engine with treatment or handling of... – Having means analyzing composition of exhaust gas
Patent
1995-05-26
1996-12-03
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Having means analyzing composition of exhaust gas
60277, 60285, F01N 328
Patent
active
055796370
ABSTRACT:
An air-fuel ratio control apparatus for an engine for reliably converging an air-fuel ratio around a stoichiometric air-fuel ratio to prevent harmful exhaust components from being discharged into the air is described. The apparatus includes a CPU which determines an inversion direction of an output of an O.sub.2 sensor on the downstream side of a catalytic converter, corrects a target air-fuel ratio .lambda.TG in a step-like fashion in the opposite direction by a skip amount and calculates a fuel injection amount every injection timing on the basis of a difference between the corrected target air-fuel ratio .lambda.TG and an air-fuel ratio .lambda. detected by an O.sub.2 sensor on the upstream side of the exhaust flow. The target air-fuel ratio is reflected immediately in the fuel injection amount at an updating rate of every ilnjection timing, so that the fuel injection amount may be controlled with an excellent responsiveness to turbulence in the air-fuel ratio. Further, upper and lower limit guard values .lambda.TGL and .lambda.TGR for the target air-fuel ratio .lambda.TG are set based on a mass of absorbed substances in the catalytic converter after learning variations in the operating parameters of the downstream side O.sub.2 sensor and the like, so that large turbulence of the air-fuel ratio on the downstream side of the catalytic converter is suppressed and the air-fuel ratio may be reliably controlled around a stoichiometric air-fuel ratio.
REFERENCES:
patent: 4693076 (1987-09-01), Chujo et al.
patent: 5359852 (1994-11-01), Curran
patent: 5491975 (1996-02-01), Yamashita
Hasegawa Jun
Yamashita Yukihiro
Hart Douglas
Nippondenso Co. Ltd.
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