Lubrication System of a Automotive Engine
Why lubricating oil?
An automobile's lubrication system refers to
the set of interacting automotive parts which are designed to supply clean oil
(the lubricant) at the correct temp and pr to different parts of the engine.
Thus preventing any damage to the engine due to overheating by the continuous
metal-to-metal contact between its parts. The main function an
automobile lubrication system is to circulate and deliver oil to all the moving
parts of an engine in order to lessen friction between surfaces that comes in
contact with each other. The lubrication system of an automobile acts to reduce
engine wear caused by the friction of its metal parts, as well as to carry off
heat.
What is Lubricating Oil?
Engine/Lubricating oil is one of the many
product that comes from crude oil. Engine oil must have certain properties so
that it can efficiently work within the engine moving parts. The API classifies
engine oil as standard or S-class for passenger car and as commercial or
C-class for heavy duty.
Lubricating oil Properties
l
Gravity
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Flash Point
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Viscosity
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Cloud Point
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Pour Point
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Carbon-Residue Test
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Ash Test
Type of Lubricating System
q
Wet
sump system
q
Dry
sump system
Wet Sump System
Oil pump sucks oil from
the bottom of the oil pan through a tube, and then forced through an oil filter
and pr feed to the main oil galleries. From the main oil galleries, the oil
passes through feed-holes into drilled passages in the crankshaft and on to the
big-end bearings of the connecting rod.
Dry sump system
In a
dry sump system, extra oil is stored in a tank outside the engine rather than
in the oil pan. There are at least two oil pumps in a dry sump - one pulls oil
from the sump and sends it to the tank, and the other takes oil from the tank
and sends it to lubricate the engine. The minimum amount of oil possible
remains in the engine.
In a
dry sump system, the oil falls to the bottom of the engine into an oil
collection pan. A scavenge pump then pumps it to an oil tank where it is stored
until the normal oil pump collects it and pumps it through the filter and
engine in the normal way.
Crankcase Ventilation
During normal operation, a small amount
of unburned fuel and exhaust gases escape around the piston rings and enter the
crankcase, referred to as "blow-by".
If
these gases had no controlled escape mechanism, the gasket joints would leak
(as they "found their own way out").also, if the gases remained in
the crankcase and condensed, the oil would become diluted and chemically
degraded over time, decreasing its ability to lubricate. Condensed water would
also cause parts of the engine to rust.
To counter this, a crankcase ventilation system exists. In all modern
vehicles, this consists of a channel to expel the gases out of the crankcase,
through an oil-separating baffle, to the PCV valve, into the intake manifold.
In a non-turbo engine, the intake manifold
is at a lower pressure than the crankcase, providing the suction to keep the
ventilation system going. A turbo engine usually has a check valve somewhere in
the tubing to avoid pressurizing the crankcase when the turbo