25-07-2014, 02:27 PM
FUEL INJECTION SYSTEM
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INTRODUCTION :
Fuel injection is a system for mixing fuel with air in an Internal Combustion Engine.
Fuel ignition is one of the important feature in an engine operating system.
The operation and efficiency of an internal combustion (IC) engine is strongly linked to its ignition timing.
It has become the primary fuel delivery system used in gasoline automotive engines, having almost completely replaced carburetors in the late 1980s.
With the advent of electronic fuel injection (EFI), the diesel and gasoline hardware has become similar.
CONTD…
It is mainly done by the usage of spark plugs in case of petrol engine ,while in case of a diesel engine the charge is compressed and ignited.
One of the first commercial fuel injection systems was a mechanical system developed by Bosch and introduced in 1955 on the Mercedes-Benz 300SL.
FUEL INJECTION SYSTEM
The function of fuel injection system is to inject proper quantity of fuel into the engine cylinders at the correct time and at a predetermined rate.
Types of fuel injection system:-
Common rail fuel injection system.
Individual pump fuel injection system
COMMON RAIL FUEL INJECTION SYSTEM
This type of fuel supply system is used in the detroit diesel engine, commonly known as Jimmy diesel. In this a single injector pump with injector known as unit injector is employed on each cylinder.
INDIVIDUAL PUMP FUEL INJECTION SYSTEM
In this fuel is drawn from the fuel tank via fuel feed pump which is operated from the injection pump camshaft.
The pump is provided with hand-priming lever so that the diesel oil can be forced into the system and the air bled out without turning the engine.
The fuel injection pump then injects definite quantity of fuel into individual cylinders, through injectors fitted on them.
THE MECHANICAL FUEL INJECTOR
It is used in continuous –injection systems.
The injector is basically a fixed orifice with a mechanical needle valve operated by fuel pressure. The amount of fuel injected depends on the pressure applied to the fuel.
It consists of mainly two parts-the nozzle and the nozzle holder connected by screwed cap, this facilitates the change of nozzle valve whenever needed.