Patent ID: 6343466
Filing Date: 2002-02-05
Classification: F01N,F02D,Y02T

Abstract:
A catalyst-deterioration diagnostic system for diagnosing a deterioration state of a catalyst, comprising:index means for obtaining an index value which is used for deciding the deterioration state of the catalyst; catalyst state estimation means for estimating a state of said catalyst at a time at which said index means has obtained the index value, as to a physical quantity which affects a catalytic action of said catalyst; correction means for correcting said index value obtained by said index means, to a value in a standard state of said catalyst previously set as to the physical quantity, by the use of an estimated result of said catalyst state estimation means; decision means having a preset criterion value, and for deciding said deterioration state of said catalyst by comparing the index value corrected by said correction means with the preset criterion value; and a generator for generating deterioration warning in accordance with a decision result by said decision means except at a temperature lower than a catalyst activation temperature.