13
Design and function
Engine, general
The engines are straight 6-cylinder, 4-stroke diesel en-
gines with overhead valves. They have direct fuel in-
jection and turbocharging.
The engines have wet, replaceable cylinder liners and
two separate cylinder blocks, each of which contains
three cylinders. The cylinder blocks are mutually inter-
changeable.
Engine lubrication is by means of a pressure lubrica-
tion system containing an efficient oil pump which
pumps out oil to two galleries in the cylinder block.
Oil is pumped out via the lubrication filter to the lubri-
cation points in the engine and via a piston cooling
valve to the oil cooler and pistons.
The piston cooling valve opens when the oil pressure
has reached a certain level, and oil is squirted into a
duct underneath the piston crown. The jet of oil is then
led via a cooling loop in the upper part of the piston.
In the oil cooler, the heat is transferred from the oil to
the cooling system of the engine.
The oil is cleaned by means of a full flow oil filter.
The cooling system is divided up into a fresh water
system and a sea water system.
The fresh water system is thermostatically controlled
and cools the cylinder block and cylinder head.
The sea water cools the fresh water via a heat ex-
changer.
Some engines can be equipped with a 1-circuit or
2-circuit hull cooling system as follows:
TAMD63 1-circuit system
TAMD71 1-circuit or 2-circuit system
TAMD72 2-circuit system
The engine version with hull cooling does not have a
heat exchanger.
The turbo compressor supplies fresh air under pres-
sure to the engine, which gives a large surplus of air.
This allows the amount of fuel injected to be in-
creased, and this gives increased engine power.
The engines are provided with sea water cooled after-
coolers, which lowers the temperature of the induction
air after turbocharging. This reduces the volume of the
air and more air (oxygen) can be supplied to the en-
gine. The additional air allows a further increase in the
amount of fuel injected, which increases engine pow-
er.
Since the induction air is cooled, the combustion and
exhaust temperatures are kept at a suitable level, de-
spite the higher power output.
Intercooling also gives lower exhaust emissions,
since combustion becomes more complete thanks to
the greater oxygen content of the induction air.
The turbine housing of the turbocharger is fresh
water cooled, the rest of the turbocharger is cooled by
the engine oil.
TAMD63-P and TAMD72 have turbochargers with
wastegates for greater low speed power. All engines
apart from TAMD63-P and TAMD72P-A, WJ-A have
an electric starting heater to facilitate starting and re-
duce exhaust smoke during starting in cold weather.
In order to further reduce exhaust emissions, the
TAMD61, TAMD62 and TAMD71 engines have a by-
pass valve for induction air. At low loading, the pas-
sage through the aftercooler is shut off and the air
which has been heated by the turbocompressor is led
directly (through the starting heater) into the induction
manifold.
On the TAMD63 and TAMD72, which have higher
compression ratios, other combustion chambers and
modified injection systems, this equipment is not
needed
The TAMD72P-A(EDC) is equipped with EDC (Elec-
tronic Diesel Control), a system which electronically
controls the regulator in the engine’s injection pump.
This system offers a reduction in exhaust emissions.
In the EDC system, the centrifugal regulator in the in-
jection pump is replaced by an electromagnetic actua-
tor.
The actuator in the regulator is operated by a control
unit which obtains information from a number of sen-
sors located on the engine and controls. The control
unit then calculates the amount of fuel to be injected
for every loading case, on the basis of this informa-
tion.
Note. On the TAMD72P-A, the EDC system controls
the starting sequence so as to reduce the exhaust
emissions to an even lower level. In order to increase
the combustion temperature before starting, the
start motor cranks the engine 4 turns before fuel is in-
jected.
To Next Page
Loading...
Need help?
General
