Patent ID: 6668545
Filing Date: 2003-12-30
Classification: F01N,F02D,Y02A,Y02T

Abstract:
A method of assessing a catalyst warm up rate of a catalytic converter connected in an exhaust system of a motor vehicle internal combustion engine downstream of a first exhaust gas sensor and upstream of a second exhaust gas sensor, the method comprising the steps of:specifying a warm-up rate of said first and second exhaust gas sensors that is faster than a nominal warm-up rate of said catalytic converter; periodically measuring a first response rate of said first exhaust gas sensor and a second response rate of said second exhaust gas sensor during a warm-up period of said catalytic converter, and computing an oxygen storage characteristic of said catalytic converter based on a ratio of switching frequencies between said first and second exhaust gas sensors; determining an oxygen storage threshold corresponding to a minimum desired catalyst warm-up rate; and indicating that the catalyst warm-up rate is good if the computed oxygen storage characteristics is greater than the oxygen storage threshold, and that the catalyst warm-up rate is bad if the computed oxygen storage characteristic is less than the oxygen storage threshold.