Page 127 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

MODULE 5 : Fuel Supply System (Diesel)

LESSON 31 - 38: Fuel supply system in diesel engines

Objectives

At the end of this lesson you shall be able to
• explain fuel sypply system in diesel engine.

Introduction Fuel supply system in diesel engines
The main function of the diesel fuel injection system is to inject the appropriate amount of fuel into the engine
cylinders at the right time and at a predetermined rate. Diesel fuel injection system is classified into solid injection
system and air injection system. In solid injection system only liquid fuel can be injected, whereas in air injection
system only liquid fuel can be injected.
Liquid fuel can be injected with compressed air. Air injection systems are less reliable and efficient and require a
compressor to deliver air at a pressure of 7 mpa or more, which consumes 10% of the power output. Therefore,
air injection system is not used at present.
Gravity Feed
• A fuel tank is more than a rectifier or a FIP.
• Mounted slightly higher than the pump.
• So when the cock is released, the fuel automatically descends under its own weight.
• This is called gravity feed.
• This method was used on older cars.
• Now this method is used on scooters, motorcycles.
Pressure feed system
In this method, the fuel feed pump draws the fuel water through the fuel water separator ferrofilter in the fuel tank
and delivers it to the fuel injection pump FIP at low pressure through the primary pre and secondary e2micro
filters. And the FIP delivers high pressure fuel to the injectors (fuel valves, fuel nozzles, atomizers) as per engine
requirements. And the injector works to spray into the combustion chamber.
Water Separator - Ferrofilter

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