Patent ID: 6453666
Filing Date: 2002-09-24
Classification: F01N,F02D

Abstract:
A method for controlling the operation of a lean-burn internal combustion engine, the exhaust gas from the engine being directed through an exhaust purification system including an emission control device that stores a constituent of the exhaust gas when the exhaust gas is lean of stoichiometry and that releases stored exhaust gas constituent when the exhaust gas is at or rich of stoichiometry, the method comprising:determining, during a lean engine operating condition, a first value representing an incremental amount of the exhaust gas constituent generated by the engine; determining a second value representing an incremental amount of the exhaust gas constituent being instantaneously stored in the device; calculating a third value based on a difference between the first value and the second value; averaging the third value over a first time period; and discontinuing the lean engine operating condition when the third value exceeds a predetermined threshold level.