Patent ID: 6076348
Filing Date: 2000-06-20
Classification: F01N,F02D,Y02T

Abstract:
An engine operating system including an exhaust aftertreatment device, with said system comprising:a fuel delivery system for providing fuel to the engine so as to cause the engine's air/fuel ratio to vary on a periodic basis;an exhaust aftertreatment device having a window of maximum operating efficiency, with said window being characterized by storage of an exhaust constituent within the aftertreatment device when the aftertreatment device is operating in the window;a sensor, located downstream from the exhaust aftertreatment device, for measuring the concentration of the stored exhaust constituent in exhaust gas flowing from the aftertreatment device and for generating a concentration signal having a value which is proportional to said concentration;a controller for operating the fuel delivery system and for receiving the concentration signals and for determining the mode of the concentration signals, as well as a measure of variation of the concentration signals from the mode, with the controller biasing the fuel delivery system to minimize variation from the mode;and with the controller outputting a signal indicating that the aftertreatment device is defective in the event that the variation of the concentration signals exceeds a predetermined threshold.