Excavator accessories SK200-5 excavator main control safety valve YN22V00002F1

     In the daily construction production, excavator is a commonly used construction machinery, which is widely used in the foundation excavation of housing buildings and cleaning after completion, urban pipeline laying, farmland water conservancy construction and other occasions, with the advantages of flexible construction and high efficiency. Excavator is generally composed of working device, rotating device, cab, walking device and hydraulic control system, which is inevitable in the hydraulic control system to use the relief valve, the relief valve in the hydraulic system mainly plays the role of constant pressure overflow and safety protection. At present, the relief valve used in excavator is pilot relief valve, as shown in Figure 1 and Figure 2. It is mainly composed of lifting head 1, main valve core 2, main valve sleeve 3, pilot valve core 4, pressure regulating spring 5 and pilot valve sleeve 6. The lifting head, main valve sleeve and pilot valve sleeve are provided with holes, and the pressure oil enters the main valve core cavity through the damping hole of the lifting head and acts on the pilot valve core. When the system pressure is less than the opening pressure of the first pilot spool, the pilot valve is in the closed state, and the inner and outer pressures of the main spool are equal. Due to the difference in internal and external areas, the main spool remains closed under the action of liquid pressure; When the system pressure is greater than the opening pressure of the pilot valve spool, the pilot valve spool is pushed away by the pressure oil, and the pressure oil flows back to the tank through the pilot valve sleeve hole and the main valve sleeve hole. At this time, the pressure drop is generated when the liquid flows through the damping hole of the lift head, so that the inner pressure of the master valve spool is greater than the outer chamber pressure, which pushes the main valve spool to open, and the hydraulic oil flows back to the tank through the main valve sleeve hole. When the system pressure drops to less than the opening pressure of the pilot spool, the pilot spool closes, and when the pressure difference between the inside and outside of the main spool is small, the opening is closed under the action of the reset spring. However, in actual use, it is found that when the above relief valve is used, the pilot valve core needs to open and close frequently, and the opening and closing performance of the pilot valve determines the performance of the relief valve, so the part of the pilot valve sleeve hole in contact with the pilot valve core cone is very important. In order to ensure the stability of the relief valve performance, the pilot valve sleeve area often requires high machining accuracy. The pilot valve sleeve hole is long, the pilot valve sleeve in the area of processing and testing are more difficult, processing accuracy is difficult to ensure, resulting in the pilot valve performance can not be effectively guaranteed, the stability of the relief valve is greatly affected, in addition, the main valve core and the main valve sleeve between the coaxiality mainly rely on the pilot valve sleeve screw positioning to ensure, because the pilot valve sleeve is longer, The slight deviation of thread positioning will also affect the fit of the main spool and the main valve sleeve, resulting in poor sealing and leakage.