ABB HT576419 Operation Manual page 7

Operation Manual / TPL65-A32 / -A33 / -A36 + TPL69-A32 / -A33
1 Preliminary remarks / 1.2 Layout and function
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Mode of operation
The turbocharger is a turbomachine and consists of the following main
components:
¡
Turbine
¡
Compressor
These are both mounted on a common shaft.
The exhaust gases from the diesel engine flow through the gas inlet cas-
ing (07) and nozzle ring (08) to the turbine wheel.
The turbine wheel (09) uses the energy contained in the exhaust gas to
drive the compressor wheel (12). The compressor then draws in fresh air,
compresses it and then forces it into the cylinders.
The exhaust gases escape to free air through an exhaust gas pipe which
is connected to the gas outlet casing (06).
The air which is necessary for operation of the diesel engine and is com-
pressed in the turbocharger is drawn through the suction branch or the
filter silencer (01) into the compressor wheel (12). This air then passes
through the diffuser (11) and leaves the turbocharger through the com-
pressor casing (13).
The rotor runs in two radial plain bearings (02/05). One plain bearing is
in the bearing bush (04), and the second one is in the axial thrust bearing
(03) at the compressor end.
The plain bearings are connected to a central lubricating oil duct which is
fed with oil from the engine's lubricating oil circuit. The oil outlet is al-
ways at the lowest point of the bearing casing (10).
Turbocharger version with compressor wheel cooling system
Depending on its range of use, the turbocharger is
provided with a compressor wheel cooling system. Com-
pressor wheel cooling means that, after the charge air
cooler at the engine end, cooled compressor air is de-
livered to the turbocharger to cool the compressor
wheel.
In view of the respective operating conditions, it is ab-
solutely essential that the compressor wheel is cooled in
order to guarantee its reliability and replacement inter-
vals. In the case of the turbocharger version with com-
pressor wheel cooling, the cooling air is supplied
through the side connection (15) in the bearing casing.
HZTL2498_EN Revision C April 2018