lubricating system.docx

Lubricating system 1.1 Defi nition: 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

1.2 Lubricating of Engine Componen t: . i) Piston and cylinders.

ii) Crankshaft and their bearings .

iii) Crankpin and their bearings.

iv) Wristpin and their bearing.

iiv) Valve gear.

Combustion chambers

i)Combustion chambers of CI engines 1. Direct injection (DI) chambers. 2. Indirect injection (IDI) chambers.

2.2 Combustion chambers of direct injection engines (DI)

Fig. 1 Hemispherical chamber

Fig. 3 Toroidal chamber

Fig. 2 Hemispherical chamber

Fig. 4 Shallow depth chamber

2.3 Combustion chamber of indirect injection (IDI)

Nozzle

Spherical shaped swirl chamber Glow plug Throat

Piston Fig.5 Ricardo Swirl Camber Comet, Mark II

Nozzle

Prechambe Orifice

Piston

Fig. 6 Precombustion chamber

Two-part energy cell Inlet and exhaust valve Cylinder head

Injector Cylinder

Piston

Two-lobed main combustion chamber

Fig. 7 Lanova Air-cell combustion chamber

ii)Combustion chambers of SI engines

Inlet and exhaust T-head type

I-head type

L-head type

L-head type

F-head type

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 System Air 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

3.3 WATER COOLING SYSTEM Types of Water Cooling System There are two types of water cooling system : Thermo Siphon System In 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 System In this system circulation of water is obtained b y a pump. This pump is driven by means of engine output shaft through V-belts.

Figure 3.3 : Pump Circulation System

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.

3.5 Water Jackets

Figure 3.6 : Water Jackets

Republic of Yemen University of Aden Faculty of Engineering Mechanical of Engineering Department