Electronic Injection Systems

ContentsBackground• Why Gasoline Injection instead of Carburetion• Type of Injection systems• Components of Injection System• EFI• Sensors for EFI• Merits and Demerits of EFI• Multi-Point fuel injection• Port Injection and Throttle Body Injection• D-MPFI and L-MPFI• Functional Divisions of MPFI• Cold Start injector• Injection Timing• Group Gasoline Injection System

BackgroundIn 1903 Wright Brothers used SI powered

Engine in which gear pump mounted for injection.

In 1906 Brazilian Santos Dumont made his first flight in Europe with Plunger Pump injector.

The last Carburetor that was installed in an American automobile was in 1990

Ford, Fiat, Mitsubishi, Daewoo and Honda etc have come out with gasoline injection systems in their models

Why Gasoline Injection instead of Carburetion?

In carburetor, uniformity of mixture is not same for multi-cylinder engine.

To overcome MaldistributionTo improve breathing capacity( Vol.

Efficiency).To eliminate Detonation or knock ( auto-

ignition).To prevent fuel loss due to scavenging.Fuel Economy

Type of Injection systems

1. Diect injection: Injection in the inlet port directly.

2. Indirect injection ( port and Manifold injection)

Continuous injection system: The air Fuel Mixture is continuously made by sreamly injection

Timed injection system: When the appropriate pressure or requirement is achieved, injection takes place.

Components of Injection System

Electronic Fuel Injector (EFI)

A usually electronically-controlled system for injecting a precise amount of atomized fuel into the cylinders or the intake airstream of an internal combustion engine.

In EFI sensors, computer systems and solenoid operated fuel injectors are used.

Injector Pulse: All modern automotive engines use fuel injectors to deliver fuel to the combustion chamber. It is simply the amount of time, measured in milliseconds (ms), a fuel injector stays open (delivers fuel) during a cylinder intake cycle.

Sensors for EFIEngine Temperature SensorAir flow sensorAir inlet temperature sensorThrottle position sensorManifold Pressure sensorCam Shaft Position sensorKnock sensor

Multi-Point fuel injectionDivisions

Port InjectionThrottle Body Injection

Port Injection

Throttle Body Injection

D-MPFI

L-MPFI

Functional Divisions of MPFI

1. Electronic control system2. Fuel system3. Air induction system

Electronic control system

Fuel system

Injection TimingThe timing at which injection takes place

inside the intake manifold is called the injection timing.

For four cyliner engine, each intake manifold will be fuel injected at specific times.

If more power or acceleration is required, injection will take more time for enough fuel.

Graphs

0.600000000000001 0.700000000000001 0.800000000000001 0.900000000000001 1 1.10

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Power vs. Discharge Coefficient

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Discharge Coefficient

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Power vs. Flow Area of Nozzle

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Power vs. Pressure Differential

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Pressure Differential (Pa)

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ConclusionsInjection is superior to carburetionIndirect injection is easier and therefore

more common to implementDirect injection is more efficientIncreasing the pressure differential across a

fuel injector is the most effective way to improve performance

Increasing the nozzle area is the easiest

Referenceshttp://en.wikipedia.org/wiki/Fuel_injectionalternativefuels.about.com/od/glossary/g/

injecpulsewidth.htmIC Engines By V Ganesan