| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a catalyst degradation diagnostic device for an internal combustion engine, which considers degradation levels of both upstream catalyst and downstream catalyst. <P>SOLUTION: An ECU 4 calculates an accumulated degradation level of the upstream catalyst 38 disposed on the upstream side of an exhaust passage 36, calculates an accumulated degradation level of the downstream catalyst 40 disposed on the downstream side from the upstream catalyst 38, calculates an oxygen storage capacity of the upstream catalyst 38, calculates an oxygen storage capacity of the downstream catalyst 40 based on the accumulated degradation levels of the upstream catalyst 38 and the downstream catalyst 40 and the oxygen storage capacity of the upstream catalyst 38, and diagnoses degradation of the upstream catalyst 38 and the downstream catalyst 40 based on the oxygen storage capacities of the upstream catalyst 38 and the downstream catalyst 40. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
