Patent ID: 8151552
Filing Date: 2012-04-10
Classification: F01N,Y02T

Abstract:
1. A deterioration determination device for an exhaust emission reduction device including an upstream catalyst that purifies exhaust gases flowing through an exhaust passage of an internal combustion engine and has an oxygen storage capability, and a downstream catalyst that purifies exhaust gases in the exhaust passage downstream of the upstream catalyst and has an oxygen storage capability, the deterioration determination device determining deterioration of the downstream catalyst, comprising: upstream oxygen concentration parameter-detecting means for detecting an oxygen concentration parameter indicative of an oxygen concentration in exhaust gases upstream of the upstream catalyst, as an upstream oxygen concentration parameter; intermediate oxygen concentration parameter-detecting means for detecting an oxygen concentration parameter indicative of an oxygen concentration in exhaust gases between the upstream catalyst and the downstream catalyst, as an intermediate oxygen concentration parameter; downstream oxygen concentration parameter-detecting means for detecting an oxygen concentration parameter indicative of an oxygen concentration in exhaust gases downstream of the downstream catalyst, as a downstream oxygen concentration parameter; control means for controlling exhaust gases flowing into the upstream catalyst by switching between an oxidation atmosphere and a reduction atmosphere; upstream OSC parameter-calculating means for calculating an upstream OSC parameter indicative of the oxygen storage capability of the upstream catalyst, using the upstream oxygen concentration parameter and the intermediate oxygen concentration parameter which are detected on the exhaust gases after the exhaust gases are switched by said control means from the oxidation atmosphere to the reduction atmosphere; downstream OSC parameter-calculating means for calculating a downstream OSC parameter indicative of the oxygen storage capability of the downstream catalyst, using the intermediate oxygen concentration parameter and the downstream oxygen concentration parameter which are detected on the exhaust gases after the exhaust gases are switched by said control means from the oxidation atmosphere to the reduction atmosphere; corrected downstream OSC parameter-calculating means for calculating a corrected downstream OSC parameter by correcting the calculated downstream OSC parameter according to the calculated upstream OSC parameter; and deterioration determination means for executing deterioration determination of the downstream catalyst, using the calculated corrected downstream OSC parameter.