Patent ID: 6499293
Filing Date: 2002-12-31
Classification: F01N,F02D,Y02T

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 a catalyst, the method comprising:determining, during a lean engine operating condition, an incremental amount of NOx generated by the engine; determining an incremental amount of NOx being instantaneously stored in the catalyst, said amount of stored NOx based on an amount of SOx stored in the exhaust purification system; calculating an estimate of NOx exiting the exhaust purification system based on a difference between said incremental NOx generated by the engine and said incremental amount of NOx being stored in the catalyst; determining a distance traveled by the vehicle; calculating an average tailpipe NOx emissions per distance based on said estimate of NOx exiting and said determined distance traveled by the vehicle, said average tailpipe NOx emissions per distance being averaged over a lean/rich cycle; and discontinuing the lean engine operating condition based on said average tailpipe NOx emissions per distance.