The choice of hydraulic valve affects the success or failure of the system

The choice of hydraulic valve affects the success or failure of the system

Correct selection of hydraulic valve：

     For any hydraulic system, the correct selection of hydraulic valves will be an important condition to make the hydraulic system design reasonable, excellent performance, easy to install, easy to maintain, and to ensure the normal operation of the system. The following is a brief description of how to select hydraulic valves reasonably from several aspects.

1. General principles of selection：

    First, determine the type of hydraulic valve according to the functional requirements of the system. Should try to choose the standard series of general products. According to the actual installation situation, choose different connection methods, such as tube type or plate type connection. Then, the rated pressure of the hydraulic valve is selected according to the maximum working pressure of the system design, and the flow specification of the hydraulic valve is selected according to the maximum flow through the hydraulic valve. For example, the overflow valve should be selected according to the maximum flow rate of the hydraulic pump; the flow valve should be selected according to the flow range controlled by the circuit, and the minimum stable flow rate should be less than the minimum stable flow rate required by the speed control range.

2. Selection of hydraulic valve installation method

     The installation method of the hydraulic valve has a decisive influence on the structure of the hydraulic device, so the appropriate installation method should be selected according to the specific situation. Generally speaking, when choosing a hydraulic valve installation method, it should be determined according to the size of the selected hydraulic valve, the complexity of the system and the layout characteristics. The several installation methods described above have their own characteristics. The threaded connection type is suitable for occasions where the system is relatively simple, the number of components is small, and the installation location is relatively spacious. Plate connection type is suitable for situations where the system is more complex, the number of components is large, and the installation location is relatively compact. Drilling holes can be drilled in the connecting plate to communicate the oil circuit, and multiple hydraulic components can be installed on this connecting plate, which can reduce the connecting pipes between hydraulic valves, reduce leakage points, and make installation and maintenance more convenient. Flange connection type is generally used for large diameter valves.

3. Selection of hydraulic valve rated pressure

     The rated pressure of the hydraulic valve is the basic performance parameter of the hydraulic valve, which indicates the pressure-bearing capacity of the hydraulic valve, and refers to the nominal pressure of the hydraulic valve in the rated working state. For the selection of the rated pressure of the hydraulic valve, the hydraulic valve of the corresponding pressure level should be selected according to the working pressure of the hydraulic system design. Generally speaking, the rated pressure value marked on the hydraulic valve should be appropriately greater than the working pressure of the system.

4. Selection of hydraulic valve flow specifications

     The rated flow rate of a hydraulic valve refers to the nominal flow rate that the hydraulic valve passes under rated conditions. The actual working flow of the hydraulic valve is related to the connection mode of the oil circuit in the system: the flow of all parts of the series circuit is equal, and the flow of the parallel circuit is equal to the sum of the flow of each oil circuit. When selecting the flow specification of a hydraulic valve, it is obviously the most economical if the rated flow of the valve is close to the working flow of the system. If the rated flow rate of the selected valve is smaller than the working flow rate, it is easy to cause hydraulic clamping and hydraulic power, and may adversely affect the working quality of the valve. In addition, the flow rate of the valve cannot be simply selected based on the rated output flow rate of the hydraulic pump, because for a hydraulic system, it is impossible for the flow rate through each circuit to be the same. Therefore, when selecting, the maximum flow that the hydraulic valve may pass through in the circuit should be considered.

For example：

     If a differential hydraulic cylinder is used in the primary circuit, when the hydraulic cylinder is reversing, the flow rate discharged from the rodless cavity is much larger than the flow rate discharged from the rod cavity, and may even exceed the maximum flow rate of the hydraulic pump. When selecting the reversing valve At the time, we should take this into consideration and achieve reasonable matching. Another example is that if some flow passes through a relatively large circuit, if a reversing valve with the same specification as the flow is selected, a greater hydraulic shock may occur when the reversing action is performed. In order to improve working performance, a directional valve with a larger specification can be used.

5. Selection of hydraulic valve control mode

     There are many control methods for hydraulic valves, which are generally selected according to the operating needs of the system and the configuration capabilities of the electrical system. For hydraulic systems with low automation requirements, small size or infrequent adjustments, manual control can be selected; for hydraulic systems with high automation requirements or control performance, electric, hydraulic, etc. can be selected.

6. Economic options

When selecting hydraulic valves, on the premise of meeting the work requirements, hydraulic valves with lower construction and cost should be selected as much as possible to improve the economic indicators of the main engine. For example, for a system that does not require high speed stability, you should choose a throttle valve instead of a speed control valve. In addition, when choosing a hydraulic valve, do not blindly choose a valve with a relatively cheap price. It is necessary to consider the reliability and working life of its work, that is, consider the overall cost. At the same time, the convenience and speed of its maintenance should also be considered, so as not to affect production.