What Is The Difference Between An Overflow Valve And A Pressure Reducing Valve In A Hydraulic System?
2023-12-11
What is the difference between an overflow valve and a pressure reducing valve in a hydraulic system?
What is the difference between an overflow valve and a pressure reducing valve in a hydraulic system? I found that many of the mechanical assembly masters in our workshop always feel a little silly and confused. So today we will talk about the similarities and differences.
Pressure control valves are used to limit the maximum pressure in hydraulic systems; such as safety valves, relief valves, etc.; used to adjust pressure, such as pressure reducing valves; used to control the sequential actions of cylinders or hydraulic motors, such as sequence valves. Used to control a certain unit or action, such as pressure relay and electric connection pressure gauge. Do you know the difference through the above understanding? not yet? Then we will focus on the characteristics of the relief valve and the directional valve.
Relief valve
In fact, the relief valve is divided into two types: direct-acting and pilot-operated. The direct-acting structure is simple, the manufacturing accuracy is not high, and the cost is low. The resistance is small and the movement is sensitive. The disadvantage is that the pressure lag is more serious, it is prone to vibration, and the control pressure is greatly affected by the overflow, so it cannot be used in high-pressure and large-flow systems, while the pilot-operated overflow valve is the opposite. The relief valve is generally used in parallel in the oil bypass of the system to regulate, stabilize and reduce the pressure; prevent the system from overloading and ensure safety.
Pressure reducing valve
The pressure reducing valve is divided into three types: fixed value, fixed difference and fixed ratio; the most common one is the fixed value pressure reducing valve. If it is not specified, the pressure reducing valve is usually a fixed value pressure reducing valve. According to the installation structure, it can be divided into superposition type, direct installation type and tube type pressure reducing valve; in general, the tube type is less used. According to the working form, it can be divided into two types: pilot type and direct-acting type. The pressure reducing valve is generally located at the branch interface of the actuator; the pressure reducing valve is mainly used to reduce the pressure of a branch oil circuit of the hydraulic system, so that the branch pressure is lower and stable than the main oil circuit pressure, within the range of the set pressure , The pressure reducing valve is also closed like a relief valve. However, as the system pressure increases, when the pressure set by the pressure reducing valve is reached, the pressure reducing valve opens, and part of the oil will pass through it and return to the fuel tank (at this time, when the oil with a certain pressure returns to the fuel tank, the temperature of the fuel tank will rise) , The oil pressure of this branch will not rise. It plays a role in reducing and stabilizing the branch
in conclusion
The structure of the pilot relief valve is different from that of the pilot pressure reducing valve:
1. The pressure reducing valve keeps the outlet pressure basically unchanged, while the overflow valve keeps the inlet pressure basically unchanged;
2. When not working, the inlet and outlet pressures of the pressure reducing valve are communicated with each other, but the inlet and outlet of the relief valve are different.
3. In order to ensure the constant setting value of the outlet pressure of the pressure reducing valve, its pilot spring cavity needs to be separately connected to the oil return tank through the oil discharge port. The overflow valve is the opposite.
The pressure reducing valve and the relief valve have different functions and different functions.
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