Method and apparatus for controlling lean-burn engine based upon predicted performance impact and trap efficiency

摘要

A method and apparatus for controlling the operation of a “lean-burn” internal combustion engine in cooperation with an exhaust gas purification system having an emissions control device capable of alternatively storing and releasing NO_x when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, determines a performance impact, such as a fuel-economy benefit, of operating the engine at a selected lean operating condition, with due consideration of the periodic rich operating condition necessary to release stored NO_x from the device. The method and apparatus further determine a measure representative of the instantaneous NO_x-storing efficiency of the device. The method and apparatus enable the selected lean operating condition as long as the determined performance impact and the determined device efficiency are each above respective predetermined minimum levels.