This document is printed from SPI². Not for RESALE
Illustration 12 g02720981
Typical example
(15) Wastegate regulator
When the load on the engine increases, more fuel is
injected into the cylinders. The combustion of this
additional fuel produces more exhaust gases. The
additional exhaust gases cause the turbine and the
compressor wheels of the turbocharger to turn faster.
As the compressor wheel turns faster, air is
compressed to a higher pressure and more air is
forced into the cylinders. The increased flow of air into
the cylinders allows the fuel to be burnt with greater
efficiency. The more efficient burning of fuel produces
more power.
A wastegate is installed on the turbine housing of the
turbocharger. The wastegate is a valve that allows
exhaust gas to bypass the turbine wheel of the
turbocharger. The operation of the wastegate is
dependent on the pressurized air (boost pressure)
from the turbocharger compressor. The boost
pressure acts on a diaphragm. The diaphragm is
spring loaded in the wastegate actuator which varies
the amount of exhaust gas that flows into the turbine.
The wastegate regulator (15) is controlled by the
engine electronic control module (ECM). The ECM
uses inputs from a number of engine sensors to
determine the optimum boost pressure. This will
achieve the best exhaust emissions and fuel
consumption at any given engine operating condition.
The ECM controls the wastegate regulator, that
regulates the boost pressure to the wastegate
actuator.
When high boost pressure is needed for the engine
performance, a signal is sent from the ECM to the
wastegate regulator. This causes high pressure in the
inlet manifold to act on the diaphragm within the
wastegate actuator (13). The actuating rod (14) acts
upon the actuating lever to close the valve in the
wastegate. When the valve in the wastegate is
closed, more exhaust gas is able to pass over the
turbine wheel. This results in an increase in the speed
of the turbocharger.
When low boost pressure is needed for the engine
performance, a signal is sent from the ECM to the
wastegate regulator. This causes high pressure in the
air inlet pipe (12) to act on the diaphragm within the
wastegate actuator (13). The actuating rod (14) acts
upon the actuating lever to open the valve in the
wastegate. When the valve in the wastegate is
opened, more exhaust gas from the engine is able to
bypass the turbine wheel, resulting in a decrease in
the speed of the turbocharger.
The shaft that connects the turbine to the compressor
wheel rotates in bearings (4) and (6). The bearings
require oil under pressure for lubrication and cooling.
The oil that flows to the lubricating oil inlet port (5)
passes through the center of the turbocharger which
retains the bearings. The oil exits the turbocharger
from the lubricating oil outlet port (10) and returns to
the oil pan.
Crankcase Breather
NOTICE
The crankcase breather gases are part of the engines
measured emissions output. Any tampering with the
breather system could invalidate the engines emis-
sions compliance.
The crankcase breather has a centrifugal separator.
The centrifugal separator has a special coating.
Engine oil that has been separated from the breather
gas is returned to the timing case. The crankcase
breather is driven by the shaft of the fuel injection
pump.
A heated connection may be installed on the pipe for
the crankcase breather. The purpose of the heated
connection is to prevent the formation of ice in cold
climates, that could lead to an obstruction of the pipe.
Valve System Components
Illustration 13 g02720989
14 UENR0623
Engine Operation
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