Patent ID: 6564543
Filing Date: 2003-05-20
Classification: F01N,F02D,Y02T

Abstract:
A method for monitoring a conditioning catalyst positioned upstream of a control exhaust gas oxygen sensor used for feedback control of an internal combustion engine using a monitoring sensor positioned upstream of the conditioning catalyst, the method comprising:sampling signals generated by the control exhaust gas oxygen sensor and the monitoring exhaust gas oxygen sensor, wherein the step of sampling signals comprises sampling the monitoring exhaust gas oxygen sensor signal for a first period of time; and sampling the control exhaust gas oxygen sensor signal for a second period of time, wherein the first and second periods are substantially equal and the second period begins after the first period, wherein the second period begins after a predetermined delay; adjusting signal samples to reduce the effect of any difference in signal amplitudes and mean values on a subsequent comparison of the signals; and comparing shapes of the signals based on the adjusted signal samples to determine operational efficiency of the conditioning catalyst, wherein the predetermined delay is based on an air/fuel ratio for the internal combustion engine.