Patent Document ID: 20020099493
Application ID: 10001817
Patent Flag: 0

Claim One:
1. An exhaust emission control system for an internal combustion engine having an exhaust system, comprising: an exhaust gas purifying means provided in said exhaust system and for storing at least one of oxygen and nitrogen oxides; an oxygen concentration sensor provided downstream of said exhaust gas purifying means; an air-fuel ratio control means for enriching an air-fuel ratio of an air-fuel mixture supplied to said engine with respect to the stoichiometric air-fuel ratio, to thereby reduce oxygen or nitrogen oxides stored in said exhaust gas purifying means; predicting means for calculating a predicted value of an output from said oxygen concentration sensor by using a predictor subroutine based on a fuzzy logic process; and determining means for determining the completion of reduction of the oxygen or nitrogen oxides stored in said exhaust gas purifying means, according to the predicted value calculated by said predicting means.