High Quality Diesel Head Rotor 1 468 336 655 1468336655 VE Pump Parts Rotor Head Spare Part

When the pressure behind the fuel pump reaches the pre-pressure of the pressure regulating spring of the pilot valve, the pilot valve opens and the main valve spring chamber is passed to low pressure. Therefore, the pressure difference between the front and rear of the main valve increases. The main valve opens and releases the fuel after the pump into the diesel return chamber, reducing the pressure after the diesel pump ensures the safety of the system, that is, the opening and closing of the main valve is controlled by the pilot valve. Opening the main valve to drain diesel reduces the pressure after the pump and prevents the system from overloading. The opening process is that the pilot valve opens first, and then the main valve opens. In the closing process, the main valve is closed first, and then the pilot valve is closed. Due to the existence of friction resistance, friction resistance prevents the main valve and pilot valve from opening when opening, and friction resistance prevents the main valve and pilot valve from closing when closing. Therefore, regardless of the main valve or pilot valve, the opening pressure is greater than the closing pressure. When the nominal flow rate through the main valve is constant, if good opening characteristics are required, the pressure when passing the nominal flow rate needs to be relatively small while the opening pressure remains unchanged. The opening of the main valve is related to the pressure difference between the upper and lower chambers of the main valve. Reducing the diameter of the main valve damping hole or increasing the length of the main valve damping hole can increase the pressure difference between the upper and lower chambers of the main valve. Based on the above analysis, the opening and closing characteristics of the safety valve are mainly related to the diameter of the main valve, the size of the main valve damping hole, the main valve spring stiffness, the size of the pilot valve damping hole and the movement resistance of the main valve.