Specific selection of hydraulic valve

Specific selection of hydraulic valve

1. Selection of directional control valve：

    The type of directional valve should be selected according to the requirements of the system work. For example, when the oil flow is required to flow in only one direction and cannot flow in the reverse direction, a one-way valve should be selected; if the actuator is required to complete the working cycle of forward, backward and stop , The three-position reversing valve should be selected; if only two working states are completed, that is, feed and retreat, the two-position reversing valve should be selected to connect or close the oil circuit; and if the actuator must complete the "fast forward one job" In the work cycle of "forward-rewind-stop" or frequent reciprocating motion, the reversing valve should usually be used to change the direction of oil flow. The directional valve can also be selected according to the working state of the system and the characteristics of the valve.

For example：

    The quality of the moving parts is small, and the reversing accuracy is not high. When the flow rate is less than 63 L/min, the electromagnetic reversing valve should be selected. Because this kind of valve has a large reversing impact, only a small flow is allowed to pass, and it is not suitable for a large flow; if The moving parts have a large mass, a large range of speed changes, and a smooth commutation requirement. When the flow rate is greater than 63 L/rain, an electro-hydraulic directional valve with stable commutation and no impact should be selected; if the system has a locking circuit, a seal should be selected The hydraulic control check valve with good performance is not selected for the reversing valve with poor sealing performance.

2. Selection of pressure control valve

    The pressure control valve controls the pressure of the hydraulic system, so it should be selected according to the working state of the hydraulic system, the pressure requirements and the function of the control valve in the system.

For example：

    In the quantitative pump throttling and speed regulation system, the movement speed of the actuator is controlled by the throttle valve; in order to keep the working pressure of the pump basically constant, an overflow valve should be used for stabilized overflow; in order to prevent the system from being overloaded, the A relief valve is connected in parallel at the outlet to protect the safety of the pump and the entire system; if there is a pressure reducing circuit in the system, a pressure reducing valve must be used to reduce the pressure of the high pressure circuit to low pressure; When performing sequential actions, sequence valves should be used to set the pressure of sequence valves to the required pressure values to control the sequence of actions of components. Pressure relays can also be used to convert hydraulic pressure into electrical signals to control the sequence of components. Sequential action; if the actuator is required to move smoothly, a back pressure valve should be installed on the circuit to form a certain oil return resistance, which can greatly improve the smoothness of the actuator. Relief valve, sequence valve, check valve and throttle valve can all be used as back pressure valve.

3. Selection of flow control valve

    The flow control valve is selected mainly according to the working state of the hydraulic system and the characteristics of the flow control valve to control the movement speed of the actuator. For example, if the actuator requires a stable speed and does not produce creep, the speed control valve should be selected. When selecting the specifications of the speed control valve, attention should be paid to the minimum stable flow of the speed control valve, which should meet the minimum speed requirements of the actuator, that is to say, adjust The minimum stable flow rate of the speed valve should be less than the minimum flow rate required by the actuator; if the flow stability requirements are particularly high, or in the case of micro-feeding, a temperature-compensated speed control valve should be selected.

    In short, the correct choice of hydraulic valve has a great bearing on the success or failure of the system. As a hydraulic designer, he should have a more comprehensive understanding of the production situation of hydraulic valves at home and abroad, especially the performance of various hydraulic valves, and the replacement and replacement of new and old products. It is also necessary to go to the use site to understand the working conditions of the hydraulic valve. Only in this way can the correct and reasonable selection of the hydraulic valve be achieved.