High pressure common rail electronic injection technology refers to a fuel supply mode that completely separates the injection pressure generation and injection process from each other in the closed-loop system composed of high pressure fuel pump, pressure sensor and electronic control unit. Its CPU can realize a number of control functions, greatly reducing the degree of fuel supply pressure changes with engine speed. Its control contents include fuel pressure control, injection timing control, injection rate control and injection quantity control. The high-pressure common rail electronically controlled fuel injection system is mainly composed of an electronic control unit, a high-pressure fuel pump, a pressure accumulator, an electronically controlled fuel injector and various sensors. In the closed loop system composed of the high-pressure fuel pump, pressure sensor and electronic control device of the excavator, the low-pressure fuel pump inputs fuel into the high-pressure fuel pump, which pressurizes the high-pressure fuel pump and delivers it to the common rail fuel supply pipe. Precise control is achieved through the oil pressure in the common fuel supply pipe. The electronic control unit measures the fuel rail pressure according to the pressure sensor of the common rail fuel supply pipe. According to the running state of the machine, the electronic control unit determines the appropriate injection period and controls the electronic injector to inject fuel into the cylinder. The high pressure fuel pipe pressure has nothing to do with the engine speed, which greatly reduces the variation of the diesel engine fuel supply pressure of the excavator with the engine speed. This will reduce the defect of traditional diesel engines. EcV controls the fuel injection volume of the injector, which depends on the dry fuel rail pressure and the solenoid valve opening time. In the process of excavator manufacturing, the traditional principle of pulsating oil supply by plunger pump is no longer used. Instead, constant high pressure fuel is directly or indirectly formed by the rail and distributed to each injector. With the help of the opening and closing of the high-speed electromagnetic on-off valve, the fuel quantity injected into the diesel engine combustion chamber by the injector is controlled regularly and quantitatively. Because the fuel pressure is extremely high and the injection hole is small, the diesel engine of the excavator can achieve the best combustion ratio and good atomization, as well as the best ignition time, sufficient energy and the least pollution emission. This is the reason why the excavator powered by the EFI diesel engine is more powerful than the direct injection excavator.
