Cooling and Lubrication of Engines

This is very useful for Automobile purpose.

1. COOLING AND LUBRICATION OF
ENGINES
Presented by:
MD. AZHAR SHERIFF
DEPARTMENT:-
MECHANICAL
ENGINEERING

2. INTRODUCTION
 COOLING OF ENGINE
The purpose of the Engine Cooling System is to
prevent the overheating of vehicle’s engine. With engine
combustion reaching extremely high temperatures, the
resulting heat needs to be dissipated.
 LUBRICATION OF ENGINE
Lubrication is the process or technique employed to
reduce friction between, and wear of one or both,
surfaces in proximity and moving relative to each other,
by interposing a substance called a lubrication.

3. PRINCIPLE
Principle Cooling of Engine
Most Internal Combustion (I.C) engines are fluid
cooled using either air cooled or a liquid cooled run
through a heat exchanger (radiator) cooled by air. In
Marine engines and some stationary engines have ready
access to a large volume of water at a suitable
temperature.

4.  Principle Lubrication of Engine
• Primary purpose is to reduce friction between moving
parts.
•No metal to metal contact occurs – cushioning (soften the
effect of an impact on).
•Friction & Abrasive wear held to a minimum.
•To absorbs shocks.
•To form a good seal between piston rings and cylinder
walls.
•To acts as cooling medium.
•Clean the engine parts.

5. CONSTRUCTION
Construction of Cooling Engine (Air cooled Engine)
Fig:- Air cooled Engine

6. Cooling Fins

7. Construction of Cooling Engine (liquid cooled
Engine)

9. Lubrication of Engine

10. WORKING
Air Cooled Engine:-
In air cooled system a current of air made to flow
past the outside of the cylinder barrel ,outer
surface area which has been considerably
increased by providing cooling fins.
The amount of heat dissipated to air depends upon :
(a) Amount of air flowing through the fins.
(b) Fin surface area.
(c) Thermal conductivity of metal used for fins.

11. Liquid Cooled System
•A liquid is circulated
around the cylinders and
absorb heat from the
cylinder walls and cylinder
head.
•Coolant absorbs heat as it
passes through the engine
and also lubricates the
water pump.
•Hot coolant enters the
radiator in which the heat
is passed on to air that is
flowing through the
radiator.

12. Working of lubricant
Lubrication is an art of admitting a lubricant (oil, grease,
etc.) between two surfaces that are in contact and in
relative motion. The purpose of lubrication in engine is to
perform one or several of the following function:-
•To reduce friction and wear between the moving parts and
thereby the energy loss and to increase the life of engine.
•To provide selling action e.g. the lubrication oil helps the piston
rings to maintain an effective seal against the high pressure
gasses in the cylinder from leaking out into the crankcase.
•To cool the surface by carrying away the heat generated in
engine components.
•To clean the surface by washing away carbon and the metal
particles caused by wear.

13. Lubrication of Engine Components
In the reciprocating engine there are many surfaces in the
contact with each other and therefore they should be
lubricated to reduce friction. The principal friction surfaces
requiring lubrication in an internal combustion engine are :-
• Piston and cylinder
•Crankshaft and their bearings
•Crank pin and their bearing
•Valve gear

14. Types of Lubrication system
The function of lubrication system is to provide sufficient
quantity of cool, filtered oil to give positive and adequate
lubrication to all the moving parts of an engine. The
various systems used for internal combustion engine
may be classified as:-
(i) Wet lubrication system
(ii) Dry lubrication system

15. (i) Wet Lubrication System
In the wet sump lubrication system, the bottom of the
crankcase contains an oil pan or sump from which the
lubricating oil is pumped to various engine components by
a pump. After lubrication these parts, the oil flow back to
the sump by gravity. Again it is picked by a pump and re-
circulated through the engine lubricating system. The main
types of wet sump lubrication system are
•splash lubrication system.
•Pressure lubrication system.
•semi pressure lubrication system.

17. (i) Dry Lubrication System
In this system, the supply of oil is carried in an external tank. An oil
pump draws oil from the supply tank and circulates it under pressure
to the various bearing of the engine. Oil dripping from the cylinder
and bearing into the sump is removed by the scavenging pump
which in turn the oil is pass through a filter, and is fed back to the
supply tank. Thus oil is prevented from accumulating in the base of
engine. The capacity of the scavenging pump is always greater than
the oil pump. In this system a filter with a bypass valve is placed in
between the scavenging pump and the supply tank. If a filter is
clogged, the pressure relief valve opens permitting oil to bypass the
filter and reaches the supply tank. A separate oil cooler with either
water or air as the cooling medium, is usually provided in the dry
sump system to remove the heat from the oil.

18. Fig:-Dry lubrication system

19. Properties of lubricants
The duties of the lubricant in an engine are many and
varied in a scope. The lubricant is called upon to limit and
control the following:
•Friction between the component and metal to metal
contact
•Overheating of the component
•Wear of component
•Corrosion
•Deposit

20. APPLICATIONS
•Lubricants are used for Automotive Engine oils,
tractors, marine and agricultural etc.,
•All types of bearings use the lubricants to
reduced the friction.
•Most useful lubricants includes hydraulic oil, air
compressor oils, gear oils, bearing and
circulating system oils, steam and turbine oils
etc.,

21. ADVANTAGES
Advantages of Cooling:-
•The advantages of using liquid cooling over air cooling
include water's higher specific heat capacity, density,
and thermal conductivity.
•A liquid cooled engine produces more power/torque
than an air-cooled one.
•A liquid cooled engine, since cooled by liquids,
maintains a better control temperature.
•Air-cooled engines are nosier and somewhat harsh than
liquid cooled engines.

22. Advantages of Lubrication:-
•Higher oil film strength with some synthetics.
•Higher viscosity index.
•improved engine reliability due to consistent oil
pressure.
•Having the pumps external to the engine makes them
easier to maintain or replace.

23. DISADVANTAGES
Disadvantages of Cooling:-
•At low engine temperature the starting of the engine
becomes difficult.
•The liquid cooling system is costlier as it has more
number of parts.
•Air cooled engines comparatively it is less efficient.
•Air cooled system is generally used in small engines.
•Cooling fins under certain conditions may vibrate and
amplify the noise level.

24. Disadvantages of Lubrication:-
•Cause heavy exhaust smoke due to burning of
lubricating oil.
•Forms deposit on piston crown and exhaust port which
affect engine efficiency.
•Requires a thorough mixing for effective lubrication.
This requires either separate mixing prior to use of
some additive to give the oil mixing characteristic.

25. CONCLUSION
 Cooling:-
A cooling system must be provide not only to prevent
damage to the vital parts of the engine(due o high
temperature), but the temperature of these components
must be maintained within the certain limits in order to
obtain maximum performance from the engine.
 Lubrication:-
In order to minimize friction between the moving parts
and hence wear, lubrication system in an engine. Is
designed to deliver clean oil at the correct temperature
and pressure to every part of the engine.

26. THANK YOU