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Lubricating system

:nitionDefi1.1

Is essential to reduce friction and wear between the components in an engine.

Function of Lubricating:

i) To reduce friction and wear between the moving part and there by energy loss and

to increase the live of the engine.

ii) To provide sealing action .

iii) To cool the surfaces by carrying away the heat generation in engine components .

iv) To clean the surfaces by washing away carbon and metal particles caused by wear

t:Lubricating of Engine Componen1.2

ii) Crankshaft and their bearings .i) Piston and cylinders..

iii) Crankpin and their bearings. iv) Wristpin and their bearing. iiv) Valve gear.

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Combustion chambers

Combustion chambers of CI engines)i

chambers.(DI)1. Direct injection

(IDI) chambers.2. Indirect injection

Combustion chambers of direct injection engines (DI)2.2

Fig. 2 Hemispherical chamber

Fig. 1 Hemispherical chamber

Fig. 3 Toroidal chamber

Fig. 4 Shallow depth chamber

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(IDI)nindirect injectioCombustion chamber of2.3

Fig.5 Ricardo Swirl Camber Comet, Mark II

Fig. 6 Precombustion chamber

Piston

Orifice

Prechambe

Nozzle

Piston

Glow plug

Throat

Nozzle

Spherical shaped

swirl chamber

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Fig. 7 Lanova Air-cell combustion chamber

Two-part energy cell

Inlet and exhaust valve

Cylinder

Cylinder

head

Injector

Piston

Two-lobed main combustion chamber

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I enginesSCombustion chambers ofii)

Inlet and exhaust

I-head type

L-head type

L-head type

T-head type

F-head type

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COOLING SYSTEMS OF IC ENGINES

3.1 INTRODUCTION

It is to be noted that the engine is quite inefficient when it is cold and hence the

cooling system is designed in such a way that it prevents cooling when the engine is

warming up and till it attains to maximum efficient operating temperature, then it

starts cooling.

It is also to be noted that :

(a) About 20-25% of total heat generated is used for producing brake power

(useful work).

(b) Cooling system is designed to remove 30-35% of total heat.

(c) Remaining heat is lost in friction and carried away by exhaust gases.

There are mainly two types of cooling systems :

(a) Air cooled system, and(b) Water cooled system

3.2 Air Cooled SystemAir cooled system is generally used in small engines say up to 15-20 kW and in

aero plane engines.

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.

Fig.3.1 Cylinder with Fins

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3.3 WATER COOLING SYSTEM

Types of Water Cooling SystemThere are two types of water cooling system :

Thermo Siphon SystemIn this system the circulation of water is due to difference in temperature

(i.e. difference in densities) of water. So in this system pump is not required

but water is circulated because of density difference only.

Figure 3.2 Thermo Siphon System of Cooling

Pump Circulation SystemIn this system circulation of water is obtained by a pump. This pump is

driven by means of engine output shaft through V-belts.

Figure 3.3 : Pump Circulation System

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3.4 Components of Water Cooling System

Figure 3.4 : Water Cooling System using Thermostat Valve

Figure 3.5 : Water Cooling System of a 4-cylinder Engine

Water cooling system mainly consists of :

(a) Radiator,

(b) Thermostat valve,

(c) Water pump,

(d) Fan,

(e) Water Jackets, and

(f) Antifreeze mixtures.

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3.5 Water Jackets

Figure 3.6 : Water Jackets

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Republic of Yemen

University of Aden

Faculty of Engineering

Mechanical of Engineering Department