| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To diagnose deterioration of a catalyst provided in each gas discharging group, in an engine having an independent gas discharging group for each cylinder group. <P>SOLUTION: Air-fuel ratio sensors 24a and 25a are provided on the upstream and downstream sides of a first catalyst 13a respectively, and on the upstream side of a position of confluence, and air-fuel ratio sensors 24b and 25b are provided on the upstream and downstream sides of a second catalyst 13b respectively, and on the upstream side of the position of confluence. An operation part works out a diagnosing value for the first catalyst 13a, based on values detected by the sensors 24a and 25a, and a diagnosing value for the second catalyst, based on values detected by the second sensors 24b and 25b. A diagnosing part diagnoses the deterioration of the catalysts, regarding the first and second catalysts as different objects to be diagnosed. Further, regarding a catalyst group including the first and second catalysts 13a and 13b as an object to be diagnosed, the deterioration as the group is diagnosed, based on a third diagnosing value worked out with the diagnosing value for the first catalyst and that for the second catalyst. <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
