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INTRODUCTION OF FUEL SYSTEM

SubjectField operation & Maintenance of Tractors & Farm

Machinery-I (FMP-206)

Presented by

KAUSHAL GADARIYA

WHAT IS FUEL ? PROPERTIES OF FUEL QUALITIES OF DIESEL FUEL FUEL TEST FUEL SUPPLY SYSTEM IN SI ENGINE COMPONENTS OF FUEL SYSTEM IN SI ENGINE CARBURETOR FUEL SUPPLY SYSTEM IN DIESEL ENGINE COMPONENTS OF FUEL SUPPLY SYSTEM OF DIESEL

ENGINE PRECAUTION IN HANDLING OF FUEL SYSTEM

CONTENTS

WHAT IS FUEL ?

It is a substance consumed by the engine to produce energy

There are some fuel used in I.C enginea. Petrol

b. Power kerosene

c. High speed diesel oil

d. Low speed diesel oil

PROPERTIES OF FUEL

In compression ignition engines, the fuel is injected at the end of the compression stroke.

The air alone compressed to a pressure of about 35 Kg/cm2

After this compression the temperature is about 600o c.

Sr.no.

Name of Fuel

A.P.I. degree

Specific gravity

Calorific value(kcal/kg)

1.Light diesel oil(L.D.O)

22 0.920 10300

2.High speed dieseloil(HSD)

31 0.820 10550

3. Power kerosine 40 0.827 10850

4. Petrol 63 0.730 11100

Table: Important properties of fuel

QUALITY OF FUEL

The quality of the fuel mainly depends upon the following properties:

1. Volatility of fuel

2. Calorific value of fuel

3. Ignition quality of fuel

a. Calorific value: Amount of heat liberated by combustion of fuel

b. Ignition quality: Ease to burning the oil in combustion chamber

c. Volatility of fuel: It has considerable effect on the performance of the engine by affecting the following

I. Ease of starting the engine

II. Degree of crankcase oil dilution

III. Formation of vapour lock

IV. Accelerating characteristics of the engine

V. Distribution of fuel in multi-cylinder engine

QUALITIES OF DIESEL FUEL

High speed diesel oil (HSD):-

High speed diesel oil is used for high speed diesel engines. It is lighter than light diesel oil. Light diesel oil (LDO):-

Light diesel oil is the main source of fuel for slow speed engines.

Contd…

For satisfactory operation, the diesel must satisfy the following requirements;

1) It must ignite readily and burn evenly.

2) It should have a low viscosity so that it can be atomized from the nozzle holes.

3) It must have some lubrication qualities to operate the valves and FI pump parts.

4) It should have minimum foreign materials, otherwise, the engine parts may rapidly wear out.

A few important tests are recommended to determine the suitability of fuels for an I.C. engine.

1) Gravity test

2) Distillation test

3) Vapour pressure test

4) Sulpher test

5) Carbon residue

6) Colour test

7) Gum test

8) Flash test

FUEL TEST

FUEL SUPPLY SYSTEM IN SI ENGINE

Diagram of fuel supply system in SI engine

WORKING PRINCIPLE OF FUEL SYSTEM IN SI ENGINE

In some spark ignition engine, the fuel tank is placed above the level of carburettor.

The fuel flows from the fuel tank to the carburetor under the action of gravity.

There are one or two filters between the fuel tank and the carburetor.

Carburetor mix the air and fuel at required air-fuel ratio according to speed and loads of the engine.

contd…

Carburetor supply air-fuel mixture into inlet manifold. Inlet manifold distribute air-fuel mixture into different

cylinder uniformly. At last the air-fuel mixture injected into the combustion

chamber. After combustion of fuel the unwanted exhaust gases flow

out through exhaust manifold

COMPONENTS OF FUEL SYSTEM IN SI ENGINE

The fuel supply system of SI Engine consists of;1. Fuel tank

2. Fuel lift pump

3. Fuel pipes

4. Sediment bowl (as a fuel filter)

5. carburetor

CARBURETOR

It is very important component of SI Engine fuel supply system.

The process of preparing air-fuel mixture away from the cylinders of an engine is called carburetion.

The device in which this process takes place is known as carburettor.

METHODS TO SETUP CARBURETOR

On the basis of ways of mounting the carburetor on the engine body, it may divided into two classes;

1. Downdraft carburetor

2. Updraft carburetor

DOWNDRAFT CARBURETOR

Mounted above the intake manifold. Air enters the upper part of carburetor. After the creation of air-fuel mixture, it flows downward

into manifold. Commonly used in automobile, trucks and stationery

engines

UPDRAFT CARBURETOR

It mounted below the engine block. The mixture flows upward into the engine.

FUNCTION OF CARBURETOR

To mix air and fuel thoroughly To atomise the fuel To regulate air-fuel ratio at different speeds and

loads To supply the correct amount of mixture at different

speeds and loads

COMPONENTS OF CARBURETOR

• It produce pressure difference in tube

• Due to low pressure, fuel sucked into tube

Venturi tube

• It maintain the constant level of fuel in carburetor

Float chamber

• To regulate the quantity of chargeThrottle

valve

• It regulate the air supply in carburetorChoke valve

• It regulate the fuel supply in the main jetEconomiser

• It is a small opening through which fuel passes from float chamber to throttleJet

FUEL SUPPLY SYSTEM IN DIESEL ENGINE

FUEL SUPPLY SYSTEM OF DIESEL ENGINE

Fuel is drawn from the fuel tank by feed pump and forced to the injection pump through fuel filter.

The injection pump supplies high pressure fuel to injection nozzles through delivery valve and high pressure pipes.

Fuel injected into the combustion chamber through injection nozzles.

contd…

The fuel that leaks out from the injection nozzles passes out through leakage pipe and returns to the fuel tank through overflow pipe.

The fuel pressure at the feed pump must be in the range of 1.5 to 2.5 kg/cm2

FLOW DIAGRAM OF FUEL IN DIESEL ENGINE

FUEL TANK

OVER FLOW PIPE

SEDIMENTALBOWL

LIFTPIMP

FILTER

INJECTIONPUMP

INJECTOR

COMBUSTIONCHAMBER

•To store the fuelFuel tank•Used as a secondary storageSediment bowl

•To force the fuel into filterLift pump•To remove the dirt materials (both P & S filter)Fuel filter

COMPONENTS OF FUEL SUPPLY SYSTEM OF DIESEL ENGINE

•Supply high pressurized fuel according to firing order of cylindersInjection pump

•To deliver the fuel into injectorsPressure pipe

•To inject the fuel into combustion chamberInjectors •Chamber in which combustion takes place

Combustion chamber

•To flow out the exhaust gases from engineExhaust manifold

There are some important components of fuel supply system;

1.Fuel filter

2.Fuel injection pump

3.Fuel injector

FUEL FILTERThere are two types of filters:

1. Primary filter :- It removes coarse material, water and dust

2. Secondary filter :- It removes fine dust particles

The filters are made of different materials like:-

3. Metal elements

4. Felt & cloth

5. Paper disc

6. Porous metal filter

FUEL INJECTION PUMP

It is a high pressure pump, which supplies fuel to the injectors according to the firing order of the engine.

It is used to create pressure varying pressure from 120 kg/cm² to 300 kg/cm².

It supply metered quantity of fuel each cylinder at proper time.

Types of fuel injection pump:

1. Multi element pump.

2. Distributer (Rotary) pump.

FUEL INJECTOR

It is the component which delivers finely atomised fuel under high pressure to the combustion chamber.

There are three types of injectors:1. Pintle type

2. Throttle type

3. Hole type

The fuel injector consists of the following components:-

1. A needle valve

2. A compression spring

3. A nozzle

4. An injector body

COMPONENTS OF FUEL INJETCTOR

PRECAUTION IN HANDLING OF FUEL SYSTEM

Fuel :1. High quality fuel is necessary to the fuel injection

pump.

2. Only filtered fuel should be supply to the fuel tank.

Fuel tank cleaning:1. Water and deposits should be drained from the fuel

tank at least every six month.

Thanks!Any questions?