Oxygen storage capacity estimation

摘要

A more precise method for determining the oxygen storage capacity of an exhaust gas aftertreatment device is presented. The most accurate capacity estimate is obtained while the engine is idling or during low load operation. The capacity is determined by integrating the output of an oxygen sensor located downstream of the device during a period of time that it takes to store more than a predetermined amount of oxygen in the device. The overall LNT efficiency can then be inferred from its oxygen storage capacity. This method allows for improved emission control and fuel economy.