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MBE 900 OPERATOR'S MANUAL
Exhaust gases from the front three
cylinders on six cylinder engines
(all four cylinders on four cylinder
engines) are routed from the exhaust
manifold through the EGR cooler,
past control and reed valves, and
mixed with the intake manifold charge
air. The addition of cooled exhaust
gases back into the combustion
air
fl
ow reduces the peak in cylinder
combustion temperature. Less oxides
of nitrogen (NOx) are produced at
lower combustion temperatures.
Exhaust
Brake/Constant-Throttle
Valves, Optional
To increase braking performance,
the engine can be equipped with an
exhaust brake on the turbocharger
in conjunction with constant-throttle
valves in the cylinder head. See Figure
15.
Figure 15 Constant — Throttle
Activation
The two systems operate
independently of each other and
in combination.
Exhaust back pressure is used by the
exhaust brake to increase braking
performance. The constant-throttle
valves use the air that escapes through
them on the compression stroke to
provide braking force.
The constant-throttles valves are
small valves which are built into the
cylinder head and positioned opposite
the exhaust valve. When open, a link
is created between the combustion
chamber and the exhaust port.
When the engine brake is switched
on, the constant-throttle valves are put
under pressure, which in turn opens
the valves.
On the 6-cylinder model, the
constant-throttle valves are activated
by engine oil pressure. On 4-cylinder
engines, the constant-throttle valves
are activated by compressor air
pressure.
The engine brake is activated by the
DDEC-VCU and can be activated
only at engine speeds up to 2700 rpm.
All information subject to change without notice.
(Rev. )
23
DDC-SVC-MAN-0055
Copyright © 2009 DETROIT DIESEL CORPORATION
Содержание EPA04 MBE 900
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