| 摘要 |
<p>An air/fuel ratio feedback control system for an internal combustion engine sets an air/fuel ratio feedback correction coefficient on the basis of an air/fuel ratio for an air/fuel mixture introduced into a combustion chamber of the engine, to causes the air/fuel ratio to approach a set point thereof. The correction coefficient consists of a rich control proportional component PR, a lean control proportional component PL and an integral component I. When the air/fuel ratio set by the feedback control system deviates from an initial set point (the stoichiometric value) due to deterioration of an oxygen sensor for detecting the air/fuel ratio, the feedback control system compensates for the deviation to cause the air/fuel ratio to approach the initial set point, by varying a ratio of the rich control proportional component PR to the lean control proportional component PL in accordance with magnitudes of rich and lean detection levels, or by correcting a balance between the rich and lean control proportional components PR and PL on the basis of a relationship between signal level varying speeds of the proportional components PR and PL. a relationship between rich and lean control times, a relationship between rich and lean detection levels or the like. <IMAGE></p> |
