4/23/2013
Cooled Exhaust Gas Recirculation
2002 ISX/M/B Engines Equipped
With EGR
 What is cooled exhaust gas recirculation?
– Exhaust gas recirculation (EGR) is where a portion of the exhaust
gas is rerouted through a cooler, and then the cooled exhaust gas
is reintroduced into fresh charge air. This mixture contains fewer
oxygen atoms per volume of charge, which reduces the flame
temperature during combustion, thus reducing emissions.
EGR System Flow
EGR Hardware - EGR Valve
 The EGR valve
regulates the amount
of exhaust gas that is
recirculated into the
intake system.
VG Control Valve
VG Turbocharger
EGR Control Valve
Charge Air Cooler
EGR Cooler
Mixing Device
Venturi
)(
 The EGR valve is
controlled by a high
speed electric motor
that is infinitely variable
between fully open and
fully closed.
EGR Measurement
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EGR Valve Internal Components
Gear
reduction
with clutch
Motor Gear mates with
gear reduction
Sector Gear
(Hidden in
this view)
Shaft for sector
gear and position
sensor
Output of
“Gear
reduction
with clutch”
- mates
with Sector
Gear
Return spring to close
valve if failure occurs
Coolant
passage for
valve guide
Flow of
Exhaust
Gas
Poppet Valve
EGR Cooler
• Tube-and-shell design
• Stainless steel
• Self-cleaning tube
design
Click the image above to play the video.
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Mixing Devices
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Variable Geometry Turbocharging
 Integrated electronic controls
 Improves performance
Variable Geometry Turbocharger
Turbine
Speed
Sensor
– vehicle acceleration from low
speeds
– Reduces turbo-lag
Compressor
Fresh Air
Shroud Plate
– Increases engine braking
power
– Allows for higher power from
smaller engines
Yoke Mechanism
– Reduces driver shifts
 Improves fuel economy
Nozzle Ring
VG Actuation
(either pneumatic or electric)
 Lowers emission levels
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VG Turbocharger Operation
“Heron Valve” Turbo Actuator
( Latter Engines )
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EGR System Flow
New EGR System Sensors
 Turbo Intake Air Temperature
 Turbo Speed
 EGR Valve Position
 Exhaust Pressure
 Exhaust Temperature
 Delta Pressure Sensor (EGR Flow Rate)
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EGR Gas Flow Measurement
 The EGR Differential
Pressure Sensor (EGR
Flow Sensor) will be
located on the air intake
connection or in the
exhaust transfer tube
depending on the engine
family.
 The EGR Differential
Pressure Sensor is used
to calculate the mass flow
of exhaust gas mixing with
the fresh air from the
charge air cooler.
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Oxygen as a function of EGR
Running Engine Demo
1.00
16% O2
0.90
17% O2
EGR rate (by mass)
0.80
18% O2
19% O2
0.70
20% O2
0.60
0.50
0.40
0.30
0.20
0.10
0.00
15
25
35
45
55
65
75
85
fresh A/F
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2002 ISX Engine Equipped with EGR
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