ZSF10-00 Direct Acting Sequence Valve LPS-10 Hydraulic Cartridge Valve

The working principle of the relief valve

(1) Direct acting relief valve.

      The liquid pressure acting on the spool is directly balanced with the spring force. When the liquid pressure exceeds the spring force, the valve port opens and the pressure oil overflows, so that the population pressure remains constant. When the pressure is reduced, the spring force causes the valve port to close.
The direct-acting relief valve has simple structure and high sensitivity, but its pressure is greatly affected by the change of overflow flow and the deviation of static pressure regulation is large. The dynamic characteristics are related to the structural type. It is not suitable for working under high pressure and large flow, and is commonly used as a safety valve or for occasions where the pressure regulation accuracy is not high.

(2) Pilot operated relief valve.

        It is composed of pilot valve and main valve. The pilot valve is used to regulate the pressure in the upper chamber of the main valve. When the liquid pressure on the pilot valve is greater than the pretightening force of the pilot valve spring, the pilot valve opens, and the damping hole on the main valve spool has liquid flow, so that the pressure difference between the upper and lower chambers of the main valve spool is generated. When the liquid pressure formed by this pressure difference exceeds the pretightening force of the main valve spring, the main valve opens and spills, the system pressure remains constant, and the oil return of the pilot valve flows through the center hole of the main valve spool to the relief chamber; When the pressure drops to the point that the liquid pressure is less than the pilot valve spring preload force, the pilot valve closes, the upper and lower chambers of the main valve spool are under the same pressure, and the main valve spring force closes the main valve port.
     

    The static pressure regulation deviation of the pilot relief valve is small, which is suitable for high pressure and large flow occasions, but the action is not as sensitive as the direct-acting relief valve.
   

  The pilot relief valve has a remote control port, which is located in the spring chamber of the main valve, and the port is connected to a remote pressure regulator (direct acting relief valve), which can realize remote pressure regulation. If the remote control port is connected back to the fuel tank through the solenoid valve, the electromagnetic relief valve is formed, which can enable the system to achieve unloading.