Patent ID: 7162860
Filing Date: 2007-01-16
Classification: F01N,F02B,F02D,F02M,Y02T

Abstract:
1. An exhaust-aftertreatment-apparatus diagnosis system for an internal combustion engine, comprising: an exhaust ambience varying section varying a ratio between an oxidizing agent and a reducing agent in exhaust gas of the engine; an exhaust aftertreatment apparatus disposed in an exhaust passage of the engine, the exhaust aftertreatment apparatus selectively executing an adsorbing operation and a reducing operation of the exhaust gas according to the ratio; a first exhaust ambience detector disposed upstream of the exhaust aftertreatment apparatus, the first exhaust ambience detector detecting a first ratio between the oxidizing agent and the reducing agent of the exhaust gas upstream of the exhaust aftertreatment apparatus; a second exhaust ambience detector disposed downstream of the exhaust aftertreatment apparatus, the second exhaust ambience detector detecting a second ratio of the oxidizing agent and the reducing agent of the exhaust gas downstream of the exhaust aftertreatment apparatus; a first deterioration diagnosing section diagnosing a deterioration of the exhaust aftertreatment apparatus on the basis of the first and second ratios obtained during an engine operating condition change from a lean burn operation to a rich burn operation or from the rich burn operation to the lean burn operation; and a second deterioration diagnosing section diagnosing the deterioration of the exhaust aftertreatment apparatus on the basis of the second ratio obtained by transiting the engine operating condition to a stoichiometric air/fuel ratio operating condition, when the first deterioration diagnosing section diagnoses that the exhaust aftertreatment apparatus is deteriorated.