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FUEL SUPPLY SYSTEM IN SIENGINE

By. Amit S. Niwalkar

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Fuel supply system in Spark Ignition InternalCombustion Engines plays an important role in the outputpower of an engine as well as its performance in terms offuel consumption. In a way to further improve the performance of

the SI Engine and better control of pollutants, an improvedfuel injection method called !I " asoline !irect Injection#has been focused for the development of SI Engines. In the

!I method, fuel is been directly injected into the cylinderlike in CI Engines.

Introduction :-

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Float chamber (function :-

Part! from fuel !u""l# :-

Fuel tan$ :- $he fuel tank made be made from pressed steel andcoated inside to prevent corrosion, or a synthetic rubbercompound or flame resistant plastic.

Fuel "i"e! :- $hese can be made from steel or plastic and aresecured by clips at several points along the underside of thevehicle.

Fuel filter! :- $o prevent dirt and fluff entering the fuel pump afilter is fitted on the suction side of the pump.

%ir filter! :- Its most important function is to prevent dust andabrasive particles from entering the engine and causing rapidwear.Fuel "um" :- $his supplies fuel under high pressure to the fuelinjection system, or under low pressure to a carburettor.

&arburettor :- $his device which atomi%es the fuel and mi&es itwhich the correct amount of air.

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"'ays#

Carburettor Fuel injection

(ulti point fuel injection

asoline directinjection

Electronic fuelinjection

$hrottle bodyinjection

)ortinjection

FUEL SUPPLY

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Carburetor System is a proven technology for manyyears and is adopted is almost all SI Engines until *++ -s. In this method air and fuel are mi&ed in there uired uantities in a device called carburettor beforesupplying to the engine cylinder. (any comple& subsystems

are re uired for the effective working of the engine as theengine is subjected to various operating conditions inpractice.

&arburettor :-

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fi' &arburettor

/ir in /ir filter

Choke valveFuel in

as and Fuel mi&ture

0enturiFloat

$hrottle valveFloat chamber

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*. $he carburettor has many wearing part. /fter wear itoperates less efficiently.1. 0apor lock in the fuel systems may result in hot weather.2. Carburettors, with their choke tubes, jets, throttle valves,inlet pipe bends, etc., do not give a free flow passage for themi&ture. $hus there is loss of volumetric efficiency on this

account.

*. It is economical.1. Its air fuel mi&ture is easily set by mechanical.

%d)anta'e! of carburettor :-

*i!ad)anta'e! of carburettor :-

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fi' Port in+ection

/ir in

Injector

Fuel spray

$his ()FI system is to supply the proper ratio ofgasoline and air to cylinders.

Multi Point Fuel In+ection :-

In the port injectionarrangement the injector isplaced on the side of intakemanifold near the intakeport. $he injector sprays

gasoline into the air, insideintake manifold.

Port in+ection :-

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fi' Throttle bod# in+ection

Injector

/ir /ir

$hrottle body Fuel spray Intake manifold

Throttle bod# in+ection :-

In the throttle body injection system an injectoris placed slightly above the throat of the throttle body. $heinjector sprays gasoline into the air in the intake manifold.

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*. Increased volumetric efficiency and hence increasedpower and tor ue, due to the absence of any restrictionsuch as ventures and other metering elements in the airpassage.1. 3etter distribution of mi&ture to each cylinder and hence

lower specific fuel consumption.2. Even in ()FI Engines there are limits to fuel supplyresponse and the combustion control because the fuelmi&es with air before entering the cylinder.

%d)anta'e! of MPFI :-

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asoline engines work by inhaling a mi&ture of

gasoline and air into a cylinder, compressing it with a piston,and igniting it with a spark4 the resulting e&plosion drives thepiston downwards, producing power. $raditional "indirect#fuel injection systems pre5mi& the gasoline and air in achamber just outside the cylinder called the intake manifold.In a direct5injection system, the air and gasoline are not pre5mi&ed4 air comes in via the intake manifold, while thegasoline is injected directly into the cylinder.

Ga!oline *irect In+ection (G*I :-

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*. 6pright straight intake ports for optimal airflow control in the cylinder.1. Curved5top pistons for better

combustion.2. 7igh5pressure fuel pump to feed pressuri%ed fuel into the injector.

fi' Ga!oline direct in+ection

$he re uired technical features to incorporate !I systemare as follows 85

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/ fuel injector "may be1# located in a throttle bodyassembly that sits on top ofthe inlet manifold. Fuel issprayed into the inletmanifold from above thethrottle valve, mi&ing withincoming air. Fuel uantity,how much fuel is injected iscontrolled by an EC6.

EC6

Fuel in

Inlet manifold

/ir in

$3 injector

fi' Electronic fuel in+ection

Electronic Fuel In+ection (EFI :-

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/n injector sprays fuel into the inlet manifold by use of asolenoid coil.'hen the coil is switch on by the EC6, it pulls the armature9needlevalve away from the no%%le, allowing pressuri%ed fuel into theengine.'hen the coil is not switched on, the spring pushes thearmature9needle against the no%%le, no fuel is injected into the inletmanifoldInjectors are more precise and efficient than carburettors.

Electricalconnector

Solenoidcoil

:eedle valve

:o%%le /rmature Spring Fuel filter

Fuel in

Electronic Fuel In+ector ,"eration :-