22 ENGINE SYSTEMS The VGT is a closed loop system that uses the Exhaust Back Pressure (EBP) sensor to provide feedback to the ECM. The ECM uses the EBP sensor to continuously monitor EBP and adjust the duty cycle to the VGT to match engine requirements. links all the vanes. When the unison ring moves, all vanes move to the same position. Unison ring movement occurs when either side of the actuator piston is pressurized by engine oil. Exhaust gas flow can be regulated depending on required exhaust back pressure for engine speed and load. VGT control Exhaust Gas Recirculation (EGR) System The EGR system includes the following:
EGR drive module EGR valve EGR cooler Air intake manifold Exhaust tube assembly, right The Exhaust Gas Recirculation (EGR) system reduces Nitrogen Oxide (NOx) emissions. NO X forms during a reaction between nitrogen and oxygen at high temperature during combustion. Combustion starts when fuel is injected into the cylinder before or slightly after the piston reaches top-dead-center. EGR flow Some exhaust from the right exhaust tube assembly flows into the EGR cooler. Exhaust from the EGR cooler flows into a passage in the air intake manifold that intersects with the EGR valve.
Figure 16 VGT control The solenoid receives a pulse width modulated signal from the ECM that indicates the on / off time that the control valve is energized. The control valve directs lube oil flow to both sides of the piston in the actuator housing. Directing oil to different sides of the piston increases or decreases exhaust back pressure. When EGR is commanded, the EGR control valve opens allowing cooled exhaust gases to enter the intake manifold to be mixed with filtered intake air then recycled through the combustion process. Actuated vanes are mounted around the inside circumference of the turbine housing.
A unison ring EGES295-2 Read all safety instructions in the "Safety Information" section of this manual before doing any procedures. Follow all warnings, cautions, and notes. ©2006 International Truck and Engine Corporation