Exhaust Gas Recirculation: Description and Operation

Exhaust Gas Recirculation (EGR) System Description







The EGR system recirculates a part of the exhaust gas back into the intake manifold. Which results in reducing nitrogen oxide (NOx) emissions. The EGR control system uses an electronic control system to ensure both driveability and low emission. The control current from the engine control module (ECM) operates the motor to control the lift amount of the EGR valve. Also, a EGR position sensor is provided at the rear of the motor to feed actual valve lift amount back to the ECM for more precision control of the EGR amount.

The EGR control starts when the conditions for engine speed, engine coolant temperature, and barometric pressure are satisfied. Then, the valve opening is calculated according to the engine speed, and target fuel injection quantity. Based on this valve opening, the drive duty of the motor is determined and the motor is driven accordingly.

A potentiometer (variable resistor) type EGR valve position sensor is employed and installed on the EGR valve body. The EGR valve position sensor is supplied reference voltage (5V) and ground at all times from the ECM. The ECM reads the EGR position sensor voltage input and determines the EGR lift position.

Explanations On Functions And Operation
Re-circulate a part of the exhaust gas of the EGR system in the intake manifold. Reduce the combustion temperature and inhibit NOx generation since inert gases may be mixed up in the intake air.

An electronic control system is used in this EGR to balance the requirements of operability and low emissions. A DC motor is operated using the control current of the Engine Control Module (ECM) to control the EGR.