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AIR MAnAgeMent SySteM
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EGR Valve
• The ECM controlled EGR (Exhaust Gas Recirculation)
valve adds cooled exhaust gases to the intake
manifold to reduce NOx emissions.
• The EGR valve is opened during steady state
throttle positions when exhaust back pressures are
higher than intake manifold pressures (boost).
EGR Flow
• The EGR valve has two valves connected by a
common shaft.
• Cooled exhaust gas enters the lower opening of the
EGR valve after leaving the vertical EGR cooler.
• When the valve opens it allows the cooled exhaust gas to
flow through two passages, one passage is through the
upper opening of the EGR valve (upper valve) and the other
is through a passage below the EGR valve (lower valve).
• Both passages merge together prior to being
mixed with the filtered incoming air before
being sent to the intake manifold.
Dual EGR Cooling System
• The EGR cooling system is an air to coolant
heat exchanger that is used to cool the exhaust
gases before they are sent to the EGR valve.
• The exhaust is routed into the EGR coolers from
the exhaust up pipes at the rear of the engine.
• The exhaust is cooled by passing through metal
tubes that are surrounded by engine coolant.
Depending on conditions, the temperature drop
across the coolers could be as much as 850°F.
• The cooled exhaust is then routed to the EGR valve
that is mounted to the inlet mixing chamber.
EGR Valve
EGR Cooler
Horizontal
EGR Cooler Vertical
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