Patent ID: 6828156
Filing Date: 2004-12-07
Classification: B01D,F01N,F02D,Y02T,Y10T

Abstract:
An evaluating method for catalyst which is installed in an exhaust gas system of an internal combustion engine; the catalyst including a NOx catalyst for purifying exhaust gas components with at least one of a three-way catalyst and an oxidizing catalyst which are evaluated based on any combination of output signals of at least two sensors for detecting specified components in the exhaust gas which are arranged at upstream, downstream, and intermediate points of said catalyst; comprisingproviding a first region for diagnosing said NOx catalyst different from a second region for diagnosing said three-way catalyst or said oxidizing catalyst wherein the first region for diagnosing said NOx catalyst is a lean driving region, and the second region for diagnosing said three-way catalyst or said oxidizing catalyst is a driving region which has an excess air ratio &lgr;=1.