International VT 365 Service Manual page 62

ELECTRONICALLY CONTROLLED VARIABLE GEOMETRY
58
movement occurs when either side of the actuator
piston is pressurized by engine oil.
Exhaust gas flow can be regulated depending on
required exhaust back pressure for engine speed and
load.
The VGT is an exhaust driven centrifugal air
compressor that uses signals from the ECM to control
intake manifold pressure. The VGT uses a set of
moveable vanes in the turbine housing to change the
flow of exhaust gases through the VGT. These vanes
can be positioned to change the angle or direction
of flow to the turbine wheel depending on engine
operating conditions. As power demands increase,
exhaust gas velocity increases in direct relation, as
does intake manifold boost pressure. Conversely, as
the flow of exhaust gas diminishes, intake manifold
boost pressure is also reduced at the same rate.
Vanes mounted around the internal circumference
of the turbine housing are connected to a unison
ring. When the unison ring moves, all vanes move
to the same position. The unison ring moves, when
either side of the actuator piston receives pressurized
engine oil, regulated by the control valve, part of
a Pulse Width Modulated (PWM) circuit regulated
by the ECM. An increase in duty cycle of the PWM
circuit routes oil through the control valve in a way
that will cause piston movement that increases
manifold pressure. Decreasing the pulse width will
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
TURBOCHARGER (VGT)
direct oil such that the manifold pressure will be
decreased. The VGT control is a closed loop system
using the EBP sensor to provide feedback to the
ECM. The ECM provides a duty cycle in response to
engine speed, engine load, manifold pressure, and
barometric pressure in order to adjust the duty cycle
to match the requirements of the engine.
The VGT increases power output by supplying
compressed air to the engine.
components are oil and air cooled.
circulated through the housing, which acts as a
heat barrier between the "hot" turbine and the "cold"
compressor.
engine oil. Oil is pumped directly from the oil filter
base, circulates to the VGT housing, and returns
to the sump through an oil drain in the VGT center
housing.
Expanding exhaust gases drive the turbine shaft
assembly to speeds over 100,000 rpm.
air entering the compressor side of the VGT is
compressed and delivered through a charge air
cooler. Hot compressed air is cooled, filling the intake
manifold at a pressure higher than atmospheric
pressure. Because considerably more air is forced
into the intake manifold, the results are increased
power, fuel efficiency and the ability to maintain
power at higher altitudes.
EGES295-2
Follow all warnings, cautions, and notes.
© 2006 International Truck and Engine Corporation
The internal
Engine oil is
Sleeve Bearings are lubricated by
Filtered