What is the composition and working principle of the diesel common rail system?

The diesel common rail fuel supply system is a closed-loop control system composed of an electronic control unit ECU, a fuel flow metering unit (including a fuel flow regulating solenoid valve), and a common rail pressure sensor.

The electronic control unit analyzes and calculates various sensor information collected based on the operating conditions of the engine, and timely and accurately controls the operation of the high-pressure fuel pump. By adjusting the flow metering valve, the high-pressure fuel in the common rail pipe reaches the required pressure value and maintains the pressure required for the corresponding working conditions set by the program, achieving adjustable injection pressure control. At the same time, the electronic control unit sends pulse commands to the electronic fuel injectors controlled by the electro-hydraulic system, Through the pulse width, the injector can be accurately controlled to inject the high-pressure fuel in the common rail into the engine combustion chamber at the best injection time, the most appropriate injection amount, the most appropriate injection rate and good spray state, so as to ensure that the engine can work in the best performance state under any working conditions.

Diesel common rail fuel supply system.