Catalyst based adaptive fuel control

摘要

An air/fuel control system and method for controlling an air/fuel ratio entering an engine are disclosed. The system comprises a controller and two sensors. In operation, a first feedback loop is created around the engine to control the oxygen concentration in the exhaust gas. A second feedback loop is created around the engine and emission control device to adjust the air/fuel ratio. An emission control device model is used to modify the air/fuel ratio adjustment. A learned integral bias table, responsive to engine speed and engine load, is provided in the second feedback loop. Entries in the learned integral bias table are modified, one at a time, based upon integrated measurements of the downstream oxygen concentration made while the engine and catalyst are under stable operating conditions.