Patent ID: 6438944
Filing Date: 2002-08-27
Classification: F01N,F02D

Abstract:
A controller for controlling an engine operating in combination with an emissions control device that releases a previously-stored first exhaust gas constituent when the engine is operated at a rich operating condition for a predetermined duration, wherein the controller is arranged to determine a value related at least in part to the presence of a second exhaust gas constituent in the exhaust gas downstream of the device upon discontinuance of the rich operating condition,the controller being further arranged to calculate the difference, if any, by which the determined value exceeds a reference value approximating a stoichiometric air-fuel ratio; to accumulate the difference until the determined value is substantially equal to the reference value; and to adjust the duration of the rich engine operating condition based upon the accumulated difference, and to reduce the duration until the accumulated difference is less than a predetermined threshold value.