Method and apparatus for accessing ability of lean NOx trap to store exhaust gas constitutent

摘要

A method and apparatus for controlling the operation of a "lean-burn" internal combustion engine (12) in co-operation with an emissions control device (36) capable of alternatively storing and releasing an exhaust gas constituent when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, determines an ability of the device (36) to store the exhaust gas constituent by initiating a lean engine operating condition immediately following a first purge event; discontinuing the first lean engine operating condition in favour of a second purge event when the instantaneous efficiency of the device falls below a reference value; and determining the amount of excess fuel necessary to release the thus-stored amount of exhaust gas constituent.