Selection of lubricating oils for varied engine performance

Thesis Overview

<p> <strong>1.0 INTRODUCTION<br>1.1 DEFINITION OF LUBRICATING OILS</strong><br>Lubricating oils are those heavy fractions of fractional distillation of crude oil which is blended with additions and which are used to reduce friction between moving surfaces. They are distinguished from other fractions of crude oil by their high boiling point [which is greater than 4000c] and their high viscosity.<br>1.2 TYPES OF LUBRICATING OILS<br>Lubricating oils are of two types, namely<br>1. automotive lubricating oils<br>2. industrial lubricating oils<br>AUTOMOTIVE LUBRICATING OILS<br>Automotive lubricants are the fluid films applied mostly to the automotive parts it comprises of the following:<br>1. engine oils [petrol and diesel]<br>2. hydrolic oils<br>3. compressor oils<br>4. gear oils<br>INDUSTRIAL LUBRICATING OILS<br>Industrial lubricants are those lubricants that are used in heavy industrial equipment. It includes<br>1. heat transfer oils<br>2. transmission oils<br><strong>1.3 THE NEED FOR LUBRICATING OILS IN ENGINES</strong><br>When one solid surface is made to slide over another, the motion is resisted by friction between the surfaces. [friction is the force which tends to oppose the motion of two objects in contact with extent depending on the speed and the load. Example of this is the overheating and eventual seizure of a dry metal bearing and the primitive method of producing fire by melting two pieces of wood together.<br>Friction can be reduced, motion facilitated, and overheating prevented by interposing a fluid film between the two surfaces. The application of the fluid film on the moving surface is known as BUBRICATION.<br>Moreover, an engine consists of metal surfaces moving in relation to one another. No matter how a metal surface is machined and how smooth it appears to be , it presents an irregular pattern of aspenties and intervening troughs. When two such surfaces come together the contact is not over the whole area but is only where the aspen ties met and it is their interlocking that accounts for the frictional resistance to motion. If sliding is enforced, friction is high owing to the interlocking. Heat will also be generated enough to weld asperities together.<br>Hence, by applying a fluid film between the surface that are apart providing the thickness of the film is greater than the height of the asperities and the load is insufficient to disrupt the film. Resistance to motion is than due solely to that offered by the fluid [that is lubricating oil]. This resistance to the flow of fluid is known as VISCOSITY of the fluid. Friction and wear are negligible.<br>During the combustion of fuel in the engine, some reactions occur if not prevented. These reactions are oxidation of the oil which lead to formation of oil insoluble matter, generation of elements present in the fuel which are released during fuel combustion. Also high pressure produced by heavy loads can have an effect in the engine. These reactions above also have some effects on the engines, the acidic substance produce react with the metal surface thereby causing wear and corrosion on these surfaces. The high pressure produced by heavy loads also result in difficulty of the moving parts to move. This also lead to friction.<br>Consequently, lubricating oils are needed in engines to:<br>1. minimize friction and wear.<br>2. to keep the engine parts licings, piston ring groves oils ways and crank shapes] clean by preventing engines of contaminants.<br>3. to protect metal surfaces against corrosion<br>4. to cool the working parts of the engine by transferring heat to water jackets and crankcase and<br>5. it acts as a sealing medium between cylinder walls and piston rings.<br><strong>1.4 TYPES OF LUBRICATION</strong><br>Lubrication is the process of controlling friction and wear by the introduction of a friction-reducing film between two moving surfaces in contact with each other. It is of different types, namely<br>1. Hydrostatic lubrication<br>2. Hydrodynamic lubrication<br>3. Elastohydrodynamic lubrication<br>4. Boundary lubrication<br>HYDROSTATIC LUBRICATION<br>This is the application of lubricating oils on systems with high load under sufficient m pressure.<br>HYDRODYNAMIC LUBRICATION<br>This is type of lubrication which deals with the application of fluid film in between the moving surfaces with the help of the design of the system to form a wedge-shaped film in which sufficient pressure is generated to support the load.<br>ELASTOHYDRODYNAMIC LUBRICATION<br>This is the application of high viscous fluid film [lubricating oil] on machines which carry high loads.<br>The viscosity of the fluid helps in load bearing capcity.<br>BOUNDARY LUBRICATION<br>This is the type of lubrication characterized by the shearing action of the adsorbed layer which is provided by the polar molecules which the lubricating oils contain. The need for this type of lubrication arises when the system is operating at high loads and the thickness of the oil may be so reduced that it is easily ruptured. Hence contact between asperities occur.<br><strong>1.5 DEFINITION OF AN ENGINE</strong><br>An engine is a complex piece of machinery in which power is applied to do work.<br><strong>1.6 THE PURPOSE OF THIS WORK</strong><br>The aim of this project is to select lubricating of the oils like viscosity, flash point and specific gravity will guide us into the confirmation of the specification which the engine manufacturers give concerning the concerned engines. This project will be of much benefit to engine users especially cdr engine owners. It will help them to find out the engine manufacturers’ specification of their engines and then need to make use of it.<br><strong>1.7 THE SCOPE OF THE PROJECT</strong><br>The topic of this project is ‘selection of lubricating oils for the performance of various engines. This project covers the selection of four different engines of vehicles and their respective lubricating oils. The reason for the selection are specified. <br></p>