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INTRODUCTION
This project is about single cylinder fuel injection system in diesel engine. The fuel injection system of diesel engine consists of fuel filters, air cleaners; fuel feed pump, fuel injection pump ,fuel injector, and fuel tank. The main difference between a diesel injection system and a petrol injection system is a fuel injection pump is used in diesel system, Instead of a carburetor in a petrol system, and all other components are same. Fuel supply system in a diesel engine has to perform certain functions. They are given below:
• Filter the fuel.
• Meter or measure the correct quantity of fuel to be injected.
• Control the rate of fuel injection.
• Atomize or break up the fuel to fine particles.
• Properly distribute the fuel in the combustion chamber.
• The functions of the fuel injection system is to inject proper quantity of fuel in to the engine cylinder at the correct time and at a pre determined speed. The fuel injection system may be broadly classified in to solid injection system and air injection system .In solid injection system only liquid fuel is injected where as in air injection system liquid fuel is injected along with the compressed airThe air injection system is less reliable , less efficient, and requires an air compressor for supplying air at high pressure, due to which reasons it has become obsolete .Thus the solid injection system is most commonly used. The functional requirements of an injection systems are;
• Introduction of fuel into combustion chamber should take place with in a precisely defined period of time.
• The metering of the amount of fuel injected per cycle should be done very accurately
• The quantities of fuel meter should vary to meet the changing load and speed requirements
• The injected rate should be such that it results in desired heat release pattern.
• The injected fuel must be broken into very fine droplets.
• The pattern of spray should be such as to ensure rapid mixing of fuel and air.
• The beginning and end of the injection should be sharp.
• The timing of injection, if desired should change as per the requirments of load and speed.
• The distribution of the metered fuel, in the case of multi cylinders engines, should be uniform among various cylinders.
• Besides above requirments, the weight and the size of the injection system must be minimum.
• It should be cheaper to manufacture and least expensive.
CHAPTER 2
COMPONENTS OF FUEL INJECTION SYSTEM
The main components of fuel injection systems are
1. Fuel tank
2. Fuel feed pump
3. Filter
4. Injection pump
5. Injector
During the operation, the fuel from the tank enters the fuel feed pump .In feed pump, the pressure of fuel is raised slightly. There the fuel is drawn in to the filter where all the dust particles are removed. From the filter, the fuel enters in to the injection pump where the pressure of air in the cylinder at the end of compression. At this high pressure fuel is sprayed in to the engine cylinder by means of fuel injector. Any spill over fuel in the injector is returned to the filter.
Fig2.1: Out Sketch of FIS
2.1 DIESEL FUEL FEED PUMP
The purpose of the diesel fuel feed pump is to transfer the fuel from the tank to the fuel injection pump. Generally diesel fuel feed pump are used in engines. They are
1. Single acting fuel feed pump
2. Double acting fuel feed pump
1. Single acting fuel feed pump
In this single acting fuel feed pump consists of a barrel, plunger return spring, roller tappet, spindle, suction and delivery valves. The plunger is driven by cam provided on the cam shaft of the fuel injection pump through roller tappet.
2. Double acting fuel feed pump
The double acting fuel feed pump set up has four valves. Two suction valves and two delivery valves.