AIR-FUEL RATIO CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE USING ION CURRENT

摘要

PROBLEM TO BE SOLVED: To solve such a problem that it is difficult to accurately determine a combustion state from an air-fuel ratio on the basis of an ion current because there is a change in the magnitude of a detected ion current value due to an individual difference between structural elements of an ion current detection device for detecting the ion current.SOLUTION: An air-fuel ratio control device for an internal combustion engine includes peak average value calculating means for calculating a peak average value for an ion current detected by an ion current detection device 60 during activating an Osensor 160, storage means for storing an ion current peak value calculated by the peak average value calculating means as an ion peak reference value, computing means for calculating an ion peak theoretical value corresponding to the air-fuel ratio of the internal combustion engine 170 after activating the Osensor 160 from the ion peak reference value stored in the storage means, and comparing means for comparing the ion peak theoretical value calculated by the computing means with the ion current peak value detected by the ion current detection device 60 after activating the Osensor 160. It determines the combustion state of the internal combustion engine 170 in accordance with the result of the comparing means.