The role of hydraulic system relief valve

1) Used to keep the hydraulic system pressure constant. As a relief valve, it is connected with the throttling element and the load in the quantitative pump system. At this time, the valve is normally open and always overflows. With the different oil requirements of the working mechanism, the overflow of the valve varies from time to time, so as to save and balance the amount of oil entering the hydraulic system, so that the pressure in the hydraulic system can be maintained. constant. However, due to the loss rate of the overflow part, it is generally only used in low-power systems with quantitative pumps. The adjustment pressure of the relief valve should be equal to the working pressure of the system.

2) Used to prevent overloading of the hydraulic system. As a safety valve, the relief valve is normally closed when the overflow valve is used to prevent system overload. When the pressure before the valve does not exceed a preset limit, the valve is closed without oil spillage. When the pressure before the valve exceeds this limit value, the valve will open and the oil will flow back to the oil tank or low-pressure circuit, thus preventing the hydraulic system from overloading. Safety valves are mostly used in systems with variable displacement pumps, and the overload pressure controlled by them is generally 8% to 10% higher than the working pressure of the system.

3) For unloading. Use a reversing valve to connect the remote control port of the relief valve with the oil tank to unload the oil circuit.

4) For remote pressure regulation. Connect the oil inlet port of the remote pressure regulating valve with the remote control port (unloading port) of the relief valve, and realize remote pressure regulation within the set pressure range of the mainstream valve.

5) For high and low pressure multi-level control. When the reversing valve connects the remote control port of the overflow valve with several remote pressure regulating valves, the multi-stage control of high and low pressure can be realized.

6) Used as a sequence valve. An oil drain port is processed on the top cover of the relief valve, and the axial hole connecting the main valve and the top cover is blocked, and the oil spill port of the main valve is used as a secondary pressure oil outlet, which can be used as a sequence valve.

7) Used as an unloading relief valve. Generally used in pump and accumulator systems. When the pump is working normally, it supplies oil to the accumulator. When the oil pressure in the accumulator reaches the required pressure, the pressure of the hydraulic system is used to operate the overflow valve to unload the pump, and the system will be supplied with oil from the accumulator and work as usual. ; When the oil pressure of the accumulator drops to the ground, the overflow valve is closed, and the oil pump continues to supply oil to the accumulator, thus ensuring the normal operation of the system.