Figure "Coolant Flow through the EGR Cooler" illustrates EGR coolant flow.
Exhaust gas enters the EGR cooler at high temperatures and is cooled by the engine coolant system to increase the density of the gas.
Figure 1. Coolant Flow through the EGR Cooler
See Figure "EGR Measurement" for EGR measurement.
Once exhaust gases begin flow through the EGR cooler and past the venturi, pressure levels are measured from the two venturi taps or ports. The delta pressure measurement, in conjunction with the EGR temperature determines the EGR flow rate.
Figure 2. EGR Measurement
See Figure "VNT Control Flow " for VNT control flow.
The VNT turbocharger is the mechanism used to change the EGR rate
The VNT is controlled via the DDEC PWM #4, see Figure "EGR Valve and VNT Control System" , which regulates the air pressure to change the VNT vane position.
Figure 3. EGR Valve and VNT Control System
Changes to the vane position, either closing or opening, result in an increase or decrease to the EGR flow rate. See Figure "VNT Control Flow " .
Red = Exhaust Gas
Yellow= Vehicle Air (VPODs)
Orange= Cooled Exhaust Gas
Green= Coolant Flow
Figure 4. VNT Control Flow
|Series 60 EGR Technician's Manual - 7SE60|
|Generated on 10-13-2008|