| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve catalyst deterioration detecting accuracy by detecting deterioration of a catalyst in consideration of an increase of emission before the catalyst activates. <P>SOLUTION: After the catalyst temperature TCAT exceeds 150°C, change width of output voltage VOX2 of an oxygen sensor provided downstream of the catalyst is added with the predetermined sampling cycle (for example, 64 ms) to obtain dataΣV reflecting purifying gas component quantity, and a deviation from a target A/F of an air-fuel ratio (A/F) detected by an air-fuel ratio sensor provided upstream of the catalyst is multiplied with the exhaust flow rate (= intake air flow rate Q), and multiplication values are added to obtain dataΣΔA/(F×Q) of fluctuation of catalyst flow-in gas component (steps 100-160). When the catalyst temperature TCAT reaches the predetermined temperature (for example, 550°C), the addedΣV is compared with a set deterioration determination value in response toΣΔA/(F×Q) to determine whether the catalyst is deteriorated or not (steps 180-210). <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
