Arrangement for controlling the air-fuel ratio of an internal combustion engine

摘要

An arrangement for controlling the air-fuel ratio of an internal combustion engine has an intake port, an exhaust port, an air-fuel mixture feed device, an opening and closing solenoid valve for correcting the air-fuel mixture fed by the air-fuel mixture feed device, dither signal generating circuit devices for generating a periodic dither signal with a pattern containing a plurality of peaks and troughs, a shift control loop device for shifting the level of the centre of the dither signal, a driver circuit for generating a driver output signal corresponding to the dither signal and detection devices for detecting the oxygen concentration in the exhaust gases flowing through the exhaust port. The arrangement is provided with devices for determining the deviation of the dither signal detected by the detector device and with analysing devices for analysing the direction and the amount of deviation of the detected dither signal from the stoichiometric air-fuel ratio. The dither signal to be applied to the driver circuit is shifted in one direction by an amount corresponding to the direction and the amount analysed by the analysing device, by means of which the deviation of the dither signal can be corrected to the stoichiometric air-fuel ratio. <IMAGE>