Degradation diagnostic manner of the emission gas measure device and

摘要

PROBLEM TO BE SOLVED: To provide the highly accurate and practicable method and apparatus for diagnosing the deterioration of a catalyst of an exhaust gas countermeasure device in which the exhaust gas from a gasoline engine is cleaned by the three way catalyst to be discharged outside, and applicable in a wide range of operation condition including an accelerated operation region.;SOLUTION: This diagnosing apparatus is provided with the O₂ sensors 11a and 11b for measuring an air/fuel ratio (A/F) changing with time at both inlet and outlet sides of the catalyst, a calculation part 12 for calculating the power spectrum of variation in the air/fuel ratio measured by the O₂ sensors 11a and 11b, a diagnosing part 13 for diagnosing the deterioration of the catalyst based on the coefficient (y-segment) of a linear expression to which the power spectrum obtained by the calculation part 12 is approximated, and a display 14 for displaying a diagnosis result.;COPYRIGHT: (C)2003,JPO