Perkins 1106C Genset Systems Operation Testing And Adjusting page 12

12
Systems Operation Section
Illustration 13
Turbocharger with the wastegate
(12) Actuating lever
(13) Wastegate actuator
(14) Line (boost pressure)
Illustration 14
Typical example
(14) Line (boost pressure)
(15) Wastegate solenoid
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. This 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 that is spring loaded
in the wastegate actuator which varies the amount of
exhaust gas that flows into the turbine.
If a wastegate solenoid (15) is installed, then the
wastegate 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 solenoid
valve, which 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
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wastegate solenoid. This causes low pressure in
the air inlet pipe (14) to act on the diaphragm within
the wastegate actuator (13). The actuating rod (12)
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 solenoid. This causes high pressure in
the air inlet pipe (14) to act on the diaphragm within
the wastegate actuator (13). The actuating rod (12)
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 an decrease in
the speed of the turbocharger.
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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.
KENR6931