This High pressure in the header forces the fuel to each of the nozzle situated in the cylinders.In the beginning a pump supplies fuel under high pressure to a fuel header.It allows flexibility in the controlling both the fuel injection quantity and injection timing and because of this the better penetration and mixing of the fuel even at low engine speed and load. The factor which differentiates the common rail injection system from other injection system is that the fuel pressure is independent of the engine speed and the load condition. In this system the liquid fuel is injected directly into the combustion chamber without the aid of compressed air. Each injection system is different from each other. Many fuel injection systems are now available in the field of automobile. The quantity of the fuel and atomization are controlled electronically using a programmable control module. In this system the fuel is distributed to the injector from a high pressure accumulator and through a rail and this rail is common to all the cylinder, because of this only it is called as common rail injection system.
A spring loaded bypass valve on the header maintains the constant pressure of 330 to 530 kg.cm in the system and returns all excess fuel to the supply tank. The injection system has to perform the important role of initiating and controlling the whole combustion process.Common rail injection system is one of the types of solid injection system. Overall performance of the engine depends on the many factors but the some of the important are, power output, economy etc, and it greatly depends on the effectiveness of the fuel injection system. The fuel injection system is the most important component in the working of C.I.