The high-pressure common rail fuel supply system of excavator is a fuel supply mode that completely separates the production of injection pressure from the injection process. In the closed loop system composed of the high-pressure fuel pump, pressure sensor and electronic control device of the excavator, the high-pressure fuel pump delivers high-pressure fuel to the common fuel supply pipe. Precise control is realized through the oil pressure in the common oil supply pipe, so that the pressure of the high-pressure oil pipe is independent of the engine speed. The change of the diesel engine oil supply pressure with the engine speed is greatly reduced. Its size depends on the pressure of the common oil supply pipe and the opening time of the solenoid valve. According to the principle of high-pressure common rail oil supply system of excavator, the high-pressure oil circuit shall be checked from the following three aspects. For reference only.
1. Check whether the common rail pressure is normal
Open the oil outlet pipe of the oil supply pump. After starting the engine, the oil is injected at the oil outlet of the oil supply pump. Preliminary inspection confirmed that the fuel supply pump can work.
2. Inspection of fuel injector
Once the fuel injector of the excavator fails, the engine cannot be started. And different from mechanical fuel injector, the engine will not emit black smoke in case of failure. If the fuel injector is reinstalled on the engine after calibration, it still cannot be started. You need to unplug the common rail pressure sensor and restart the machine to start the engine. After that, you only need to plug in the common rail pressure sensor again to work normally for 20 minutes. Because the pressure of high-pressure common rail is very high. If the fuel quality is poor, the fuel injector will be stuck or worn, and the fuel injection of the fuel injector is realized by the pressure difference. As a result, the stuck fuel injector will not inject fuel, which makes it impossible to increase the fuel delivery as a multi-stage centrifugal pump of a mechanical pump before starting. The fuel supply can be increased by unplugging the common rail pressure sensor. Therefore, the engine can be started even if one or two injectors do not work well. Disconnect the battery electrode 1 every time the excavator is repaired. As the voltage of the fuel injector exceeds 100 V, failure to open it may cause accidents.
3. Inspection of excavator oil supply pump
Except for small faults such as stuck check valve, few major faults occur in plunger pump. The gear pump has more faults than the plunger pump. The main reason is that the lubricity of diesel oil is poor and the side face of the gear is easily worn and damaged, resulting in too low oil supply pressure and failure to start.
