Injection system

1. Prepared By:
Upadhyay Ayush.
(150123119053)
GANDHINAGAR INSTITUTE
OF
TECHNOLOGY
ACTIVE LEARNING ASSIGNMENT
ON
“Type of Injection System”
INTERNAL COMBUTION ENGINE[2161902]
MECHANICAL 6 (D3)
GUIDED BY:-
Prof. HARDIK GOHEL

2. Introduction
 Fuel-Injection System is vital to the working and
performance of CI engine. This system serves the purpose
of initiating and controlling the combustion to meet the
demand requirements.
 Fuel is injected into combustion chamber towards the end
of compression. It is atomized as it enters under high
velocity and the droplets get vaporized to form a fuel-air
mixture. Due to continued heat transfer from hot air to fuel,
the fuel reaches to its self ignition temperature to ignite
spontaneously initiating combustion. Depending upon the
demand requirements the fuel injection system continues
to deliver the fuel during initial part of combustion.
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3. Classification
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Injection
System
Air
Injection
Solid Or
Airless
Injection
Common rail
system
Individual
pump and
injector system
Distributor
system

4. Air Injection System
 In this system fuel is injected along wit high pressure air into
combustion chamber. The pressure of this air is about 70 bar. A
multistage air compressor is required to supply the blast of air at
high pressures. A fuel pump draws fuel from fuel tank through a
filter and discharge a definite quantity into an injector. The high
pressure air from compressor is also led to the injector valve which
force the fuel, through the nozzle, when it is opened mechanically.
 This type of system is not used now-a-days in diesel engines.
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Advantages:-
 It provides good atomization and distribution of fuel.
 Fuel pump needs to develop less pressure.
 It requires high pressure multi stage compressor.
 Air compressor needs extra maintenance.
Disadvantages:-

6. Solid Injection
Or
Airless injection system
 In solid Injection system , fuel is directly injected into the
cylinder without aid of compressed air. That’s why this system
is called solid or airless injection system.
 Fuel is supplied at very high pressure (about 200 bar) from
fuel pump to fuel injector from where it is injected to the
combustion chamber with the help of injector.
 There are three types as:
1. Common rail system
2. Individual pump and injector
3. Distributor injection system
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7. Common Rail Injection
System
 In this system, single fuel pump supplies high pressure
diesel oil to common rail or header.
 High pressure in the header forces fuel to each of the
nozzle. At given instant, the fuel is injected in a specific
cylinder by a mechanically operated valve, by means of a
push rod and rocker arm.
 The amount of fuel is regulated by varying the length of
the push rod stroke. The pressure in header is as per
injector design for penetration & dispersion of fuel in
combustion chamber.
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8.  It can control fuel supply according to load and speed of the
engine.
 Only one pump is required for multi cylinder engine.
 The arrangement of system is very simple & Maintenance
cost is less.
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Advantages:-
Disadvantages:-
 Very accurate design and workmanship is required.

9. Individual Pump & Injector
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In this system , individual fuel pump is provided for each
nozzle. The metering of fuel quantity and control of injection
timing are done by the each pump for corresponding nozzle.
 The needle valve in nozzle is actuated by fuel oil pressure.
The amount of fuel entering the cylinders is regulated by
changing position of control rack.

10. Distributor Injection
System
 In this system, the pump is used to pressurizes, meters and times
the injection. Then fuel is supplied to central distributor block.
From distributor block fuel is distributed to each cylinder in correct
firing order by cam operated poppet valves which open to admit
fuel to nozzles.
 The amount of fuel to entering the cylinders is regulated by
changing position of control rack. The number of injection strokes
per cycle for the pump is equal to the number of cylinders.
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