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Air-fuel ratio control system for an automotive engine

Patent ·
OSTI ID:6888761
An air-fuel ratio control system is described for an automotive engine, comprising: an O/sub 2/-sensor for detecting oxygen concentration of exhaust gas and for producing a feedback signal; first means responsive to the feedback signal for producing an air-fuel ratio signal; second means for producing a deviation signal representing the air-fuel ratio dependent on the air-fuel ratio signal from a desired air-fuel ratio; a first lookup take storing basic fuel injection pulse widths from which one of pulse widths is derived in accordance with engine operating conditions; a second lookup table storing maximum correcting quantities for correcting a derived basic fuel injection pulse width in order to correct deviation of air-fuel ratio due to change of a characteristic of a device used in the engine; third means for producing a necessary correcting quantity by multiplying a learning coefficient and a derived maximum correcting quantity; fourth means for producing a desired fuel injection pulse width in accordance with the necessary correcting quantity and the derived basic fuel injection pulse width; fifth means for updating the learning coefficient with a correcting value when deviation represented by the deviation signal is out of an allowable range; the correcting value being gradually reduced at every updating.
Assignee:
Fuji Jukogyo Kabushiki, Kaisha, Tokyo
Patent Number(s):
US 4771753
OSTI ID:
6888761
Country of Publication:
United States
Language:
English