Patent ID: 7254478

Claim:
A method of estimating an airflow delivered to an exhaust manifold of an internal combustion engine by an air injection reaction system including a driven air pump and a plenum coupling an outlet of the air pump to the exhaust manifold, the method comprising the steps of: estimating an airflow through the pump based on an operating parameter of the pump, an inlet pressure of the pump, an inlet air temperature of the pump, and an estimate of an air pressure in said plenum; estimating the airflow delivered to the exhaust manifold based on a pressure in the exhaust manifold, an air temperature in the plenum, and the estimate of the air pressure in said plenum; and updating the estimate of the air pressure in said plenum based on a difference between the estimated airflow through the pump and the estimated airflow delivered to the exhaust manifold, and the air temperature in the plenum.