Theory of Operation 1—EGR Valve 8—From Air Cleaner B2—Camshaft Position Sensor B12—Fuel Rail Temperature 2—Exhaust Manifold 9—To Aftercooler B3—Barometric Pressure Sensor 3—Intake Manifold 10—Exhaust Sensor B60—EGR Position Sensor 4—EGR Cooler 11—Engine Coolant In B4—Engine Coolant M3—EGR Valve Actuator 5—Lead Valve 12—Engine Coolant Out Temperature Sensor 6—Engine A1—Engine Control Module B7—Intake Air Temperature 7—Intake Air from Aftercooler B1—Crankshaft Position Sensor Sensor EGR recirculates a portion of the engine exhaust gas into the intake manifold to mix with intake air.
The recirculation of exhaust gas helps lower the combustion temperature, which limits emissions of nitrogen oxide (NOx). close the EGR valve. The ECM uses the EGR position sensor (B60) to detect the EGR valve position. The EGR cooler (4), through which EGR gas passes, cools down high temperature EGR gas. The cooled EGR gas mixes with intake air in the intake manifold to lower the combustion temperature, which limits NOx emissions. The amount of EGR is controlled by opening and closing the EGR valve (1), installed between the exhaust manifold (2) and intake manifold (3).
The engine control module (ECM) (A1) operates the EGR valve based on engine speed, engine coolant temperature, intake air temperature, fuel injection amount, and barometric pressure. The ECM supplies power to the EGR valve actuator (M3) to open and The lead valve (5) in the EGR system is a check valve that stops backward flow of EGR gas and prevents intake air from entering the EGR gas passage. The valve increases the amount of EGR by keeping the EGR gas flowing in the same direction. 9010 05 17 JC89288,0000038 –19–30JAN06–2/2 TM2361 (24JUN08) 9010-05-17 450DLC Excavator Operation and Tests 062608 PN=265