Control system
Patent
·
OSTI ID:6529559
An air-fuel ratio control system for an internal combustion engine comprises an intake passage, an air-fuel mixture supply means, electromagnetic means for correcting the air-fuel ratio of the air-fuel mixture supplied by the air-fuel mixture supply means, an exhaust passage, and a feedback control system. The error signal in the feedback control system is oscillated by a dither signal having a periodical pattern for oscillating the air -fuel ratio of the mixture. The dither signal comprises a plurality of positive excursions and negative excursions, and at least one of the positive excursions is lower than the other and at least one of the negative excursions is lower than the other. The dither signal is applied to the electromagnetic means for oscillating the air-fuel ratio of the mixture. A detector senses the concentration of exhaust gases. The detector produces an output signal in which the portion corresponding to the low positive excursion or low negative excursion of the dither signal is removed, when the air-fuel ratio of the mixture deviates from the stoichiometric ratio. A comparing circuit compares the shape of the waveform of the output signal of the detector with the dither signal for generating an output corresponding to the removed portion. The output signal is fed to a shift signal generating crcuit for shifting the dither signal for correcting the deviation of value of the controlled output. The period of the dither signal is reduced as the engine speed increases for accurate detection of the air-fuel ratio of the exhaust gases.
- Assignee:
- Fuji Jukogyo K K (Japan)
- Patent Number(s):
- US 4363305
- OSTI ID:
- 6529559
- Country of Publication:
- United States
- Language:
- English
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