Iveco Stralis AT/AD. Manual — part 29
Compressed air (hot)
Intake air
Engine exhaust gas
Compressed air (cooled)
Figure 206
The turbocharging system consists of:
- air filter;
- variable geometry turbocharger;
- “intercooler” radiator.
44916
TURBOCHARGING DIAGRAM
TURBOCHARGER
Operating principle
The variable geometry turbocharger (VGT) consists of a
centrifugal compressor and a turbine, equipped with a
mobile device which adjusts the speed by changing the area
of the passing section of exhaust gases to the turbine.
Thanks to this solution, gas velocity and turbine speed can
be high even when the engine is idling.
If the gas is made to go through a narrow passage, in fact,
it flows faster, so that the turbine rotates more quickly.
The movement of the device, choking the exhaust gas
flowing section, is carried out by a mechanism, activated by
a pneumatic actuator.
This actuator is directly controlled by the electronic control
unit by a proportional solenoid valve.
The device is in maximum closing condition at idle speed.
At high engine operating speed, the electronic control
system is activated and increases the passing section, in
order to allow the in-coming gases to flow without
increasing their speed.
A toroidal chamber is obtained during the casting process
in the central body for the passage of the coolant.
102
ENGINE F2B
S
TRALIS
AT/AD
Base - January 2003
TURBOCHARGING
Figure 207
1
2
3
4
5
6
1) Service tank
2) Shut-off solenoid valve
3) Air filter
4) VGT control solenoid valve
5) Actuator pressure sensor
6) Turbine actuator
CONTROL AIR SYSTEM DIAGRAM
ENGINE F2B
103
S
TRALIS
AT/AD
CROSS-SECTION OF TURBOCHARGER
1. Air delivery to the intake manifold - 2. Compressor - 3. Air inlet - 4. Actuator - 5. Exhaust gas flow-rate adjustment ring -
6. Exhaust gas inlet - 7. Exhaust gas outlet - 8. Turbine - 9. Exhaust gas flow-rate control fork
71759
Figure 208
1. Air delivery to the intake manifold - 2. Compressor - 3. Air inlet - 4. Actuator -
5. Exhaust gas speed governor - 6. Exhaust gas inlet - 7. Exhaust gas outlet - 8. Turbine
71734
CROSS-SECTION OF MAXIMUM FLOW
71733
CROSS-SECTION OF MINIMUM
FLOW
104
ENGINE F2B
S
TRALIS
AT/AD
Base - January 2003
Figure 209
60754
60753
1. Slide guide - 2. Compressor - 3. Slide rods - 4. Compressor fan - 5. Lubrication bushings -
6. Exhaust gas flow-rate adjustment ring - 7. Exhaust gas fan - 8. Gas exhaust body -
9. Locking rings - 10. Oil delivery - 11. Oil outlet - 12. Actuator drive shaft
Figure 210
ENGINE F2B
105
S
TRALIS
AT/AD
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