【正文】 dules, such as sensors, the electronic control unit, and key ponents of the monrail system are the are fitted with a rapidaction valve(solenoid valve or piezotriggered actuator)which opens and closes the permits control of the injection process for each the injectors are fed by a mon fuel rail, this being the origin of the term “mon rail”.In the monrail fuelinjection system, the function of pressure generation and fuel injection are injection pressure is generated independent of the engine speed and the injected fuel electronic diesel control(EDC)controls each of the ponents.(1)Pressure generation and fuel injection are separated by means of an accumulator under pressure is supplied to the accumulator volume of the monrail ready for continuously operating highpressure pump driven by the engine produces the desired injection in the fuel rail is maintained irrespective of engine speed or injected fuel to the almost uniform injection pattern, the highpressure pump design can be much smaller and its drivesystem torque can be lower than conventional fuelinjection results in a much lower load on the pump highpressure pump is a radialpiston mercial vehicles, an inline fuelinjection pump is sometimes fitted.(2)Pressure Control The pressure control method applied is largely dependent on the way of controlling rail pressure is to control the highpressure side by a pressurecontrol not required for injection flows back to the lowpressure circuit via the pressurecontrol type of control loop allows rail pressure to react rapidly to changes in operating point( the event of load changes).Control on the highpressure side was adopted on the first monrail pressurecontrol valve is mounted preferably on the fuel some applications, however, it is mounted directly on the highpressure way of controlling rail pressure is to control fuel delivery on the suction metering unit flanged on the highpressure pump makes sure that the pump delivers exactly the right quantity of fuel rail in order to maintain the injection pressure required by the a fault situation, the pressurerelief valve prevents rail pressure from exceeding a control on the suction side reduces the quantity of fuel under high pressure and lowers the power input of the has a positive impact on fuel the same time, the temperature of the fuel flowing back to the fuel tank is reduced in contrast to the control method on the highpressure twoactuator system is also a way of controlling rail pressure, which bines pressure control on the suction side via the metering unit and control on the highpressure side via the pressurecontrol valve, thus marrying the advantages of highpressureside control and suctionside fueldelivery control.(3)Fuel injectors spray fuel directly into the engine’s bustion are supplied by short highpressure fuel lines connected to the fuel engine control unit controls the switching valve integrated in the injector to open and closethe injector injector opening times and system pressure determine the quantity of fuel a constant pressure, the fuel quantity delivered is proportional to the switching time of the solenoid is, therefore, independent of engine or pump speed(timebased fuel injection).(4)Potential Hydraulic the functions of pressure generation an