Exhaust gas recirculation system

摘要

EGR system for an internal combustion engine comprises a stepper motor driven EGR valve (150) to control the rate of exhaust gas recirculation in the engine and an electronic controller (EEC 100) for determining a desired EGR percent mass flow rate as a function comprising a rotational speed value and an aircharge value of the engine, converting the EGR percent mass flow rate to an EGR mass flow rate value, adjusting the EGR mass flow rate value as a function of an exhaust gas temperature value and an absolute exhaust gas backpressure value using MAP values, determining a pressure ratio value across an EGR orifice (155) cooperating with the EGR valve, and determining a required number of motor steps as a function of the adjusted EGR mass flow rate value and the pressure ratio value to achieve the desired EGR percent mass flow rate.