Patent ID: 6308515
Filing Date: 2001-10-30
Classification: F01N,F02D,Y02T

Abstract:
A method for accessing the ability of an emissions control device to releasably store a quantity of a constituent of exhaust gas generated by lean-burn operation of an internal combustion engine, wherein the device stores the quantity of the exhaust gas constituent when the exhaust gas directed through the device is lean of stoichiometry and the device releases a previously-stored amount of the exhaust gas constituent when the exhaust gas directed through the device is rich of stoichiometry, the method comprising:determining that the engine is operating at a first lean operating condition immediately following a first rich engine operating condition, the first rich engine operating condition having been sufficient to release substantially all of the previously-stored amount of the exhaust gas constituent from the device, the first lean operating condition operating to store an additional amount of the exhaust gas constituent in the device;determining, during the first lean operating condition, a first measure representative of the instantaneous efficiency of the device to remove the exhaust gas constituent from the exhaust gas;initiating a second rich operating condition when the first measure falls below a reference value, the second rich operating condition being characterized by the combustion of a quantity of fuel in excess of a stoichiometric quantity of fuel sufficient to release substantially all of the additional amount of the exhaust gas constituent from the device; anddetermining an ability of the device based on the quantity of excess fuel.