What is the working principle of Exhaust Gas Recirculation?
1 Answers
Exhaust Gas Recirculation (EGR) system works to reduce the emission of nitrogen oxides (NOX) in the exhaust gases. Below is an introduction to the EGR system: 1. The EGR valve controls the amount of exhaust gas flowing back from the exhaust manifold to the intake manifold through three metering orifices of increasing diameters, creating seven different flow combinations. Each metering orifice consists of a solenoid valve and a needle valve. When the solenoid is energized, the armature is pulled upward by the magnet, opening the metering orifice. The rotary needle valve ensures good sealing when the EGR valve is closed. 2. The EGR valve typically opens under the following conditions: (1) When the engine is warm and running. (2) When the engine speed exceeds idle. 3. The ECM controls the EGR system based on inputs from the engine coolant temperature sensor, throttle position sensor, and air flow sensor.