Proper fuel Injection in Engine is most important fact in any Diesel Engine.Mostly two methods are in use for Fuel Injection.
01)Air Blast Injection:-
This is old method which is obsolete now a days.In this method Air is Compressed at very high pressure by means of a Air Compressor.A blast of this Air is then injected carrying the Fuel along with it into the Cylinder.
Due to varying Pressure of Injection Air the rate at which the fuel is admitted can be effectively controlled.The combustion takes place nearly at constant Pressure.Due to high Pressure Air Compressor weight increase and net output of Engine is decrease.
This Air less Injection System.The Fuel under Pressure is directly injected into the combustion Chamber at Atomised State.This is useful for small and big Diesel Engines.It requires a Pump to deliver the fuel at High Pressure.This Fuel Injection System further divided into two system.
A)Individual Pump System:-
In this system each cylinder has its own individuals High pressure Pump and a metering unit.This is quite compact system.It has a higher manufacturing cost due to close tolerance are required at production.
B)Common Rail System:-
The Fuel is pumped by a Multi-Cylinder Pump into a common rail,the pressure in which is controlled by a Relief Valve.
The Advantages of Solid Injection System.
01)Simple in construction.
02)Lighter in weight.
03)Lower Fuel consumption.
04)Lower initial cost.
05)No High Pressure Air compressor required to start the Engine.