Operation Section
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7.2 E-EGR System (Electric-Exhaust Gas Recirculation)
(1) General Description
• The E-EGR system is an electronically controlled EGR system. The EGR system recirculates a portion of the exhaust
gases into the intake manifold in order to lower the combustion chamber temperature and reduce NOx emissions.
However, operation of the EGR system may reduce engine power output and affect drivability. For this reason, in the
E-EGR system, the engine ECU controls the EGR to achieve an optimal EGR amount.
Operation Conditions Example
- This operates in the operation region fulfilling the starting conditions below (one example).
(2) Operation
• After the vacuum pump generates a vacuum, the E-VRV (electric-vacuum regulation valve) regulates the vacuum and
directs it to the diaphragm chamber of the EGR valve. In response to this vacuum, the diaphragm pushes the spring
downward, which determines the opening of the EGR valve and controls the EGR volume.
• The EGR cooler, which is provided in the EGR passage between the cylinder head and the intake passage, cools the
EGR in order to increase the EGR volume.
• The EGR cutoff VSV, which opens the diaphragm chamber to the atmosphere when the EGR valve is closed, helps
to improve response.
Injection Quantity
Engine Speed
· Engine Operating Conditions
· · · · · Except during engine warm-up and startup,
does not overheat, etc.
· EGR Operating Range
· · · · · · · · For Engine Medium Load
Q000501E
Q000903E
EGR Cooler
EGR Valve
Coolant
Diaphragm
Vacuum Damper
Spring
EGR Shut-Off VSV
Vacuum Pump
E-VRV
Control Unit
Engine Speed
Accelerator Opening
Intake Air Pressure And
Atmospheric Pressure
Coolant Temperature
Intake Air
Relationship Between Vacuum and EGR Valve Opening
Low
Small
High
Large
Vacuum
EGR Valve Opening
Engine
Exhaust
Manifold
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