hydraulic control valveComponents that control the pressure, flow and direction of liquid media.The valve that controls the pressure part is calledpressure controlValvewhile the one that controls the flow is calledflowControl valvewhich controls on, off and flow direction is calleddirectionControl valve.The specifications and models of various hydraulic control valves can be based on the higher pressure of the system and the actual flow through the valve (checked from the working condition diagram and system diagram) and consider the control characteristics, stability, oil port size and external dimensions of the valve , installation connection method, operation method, etc., selected from product catalogs or catalogs.
Precautions for selection of hydraulic control valve:
For ordinary one-way valves with simple structures, attention should be paid to the reasonable selection of their opening pressure: lower opening pressure can reduce the resistance loss of liquid flow through the one-way valve; however, for the one-way valve used as a back pressure valve , the opening pressure is higher to ensure sufficient back pressure. For hydraulically controlled check valves, in addition to the relevant precautions in this type of reversing valve, in order to avoid abnormal vibration and noise in the system, attention should also be paid to selecting a reasonable pressure relief method: When the pressure is high, the external leakage type should be selected, and the internal leakage type can be selected in other cases.
Installation and connection of hydraulic valve
Since the installation and connection method of the valve has a decisive influence on the structural type of the subsequent designed hydraulic device, when selecting a hydraulic valve, the integration method of the hydraulic control device should be well known. For example, the plate type connection hydraulic valve is used, because the valve can be installed on the oil circuit board or the oil circuit block, on the one hand, it is convenient for system integration and hydraulic device design rationalization, on the other hand, it is not necessary to dismantle the oil pipe when replacing the hydraulic valve, and the installation and maintenance are more convenient; If a superimposed valve is used, it is necessary to study the series spectrum of the superimposed valve according to the pressure and flow rate for selection, and so on.
Rated pressure and rated flow of hydraulic valves
The rated pressure and rated flow of each hydraulic control valve should generally be close to its operating pressure and flow. For systems with high reliability requirements, the rated pressure of the valve should be higher than its operating pressure. If the rated pressure and rated flow rate are lower than the operating pressure and flow rate, it will easily cause hydraulic clamping and hydraulic power and have an adverse effect on the working quality of the valve; for the sequence valve and pressure reducing valve in the system, the flow rate should not be much less than the rated flow, otherwise vibration or other unstable phenomena may easily occur. For the flow valve, attention should be paid to its small and stable flow.
Actual flow of hydraulic valve
The actual flow of the hydraulic valve is related to the series and parallel connection of the oil circuit: the flow of each part of the series oil circuit is equal; the flow of the parallel oil circuit working at the same time is equal to the sum of the flow of each oil circuit. In addition, for a system using a single-piston rod hydraulic cylinder, attention should be paid to the difference in the oil return flow when the piston is extended and retracted: the ratio of the oil return flow of the rodless cavity when the piston is retracted to the oil return flow of the rod cavity when the piston is extended is the same as The ratio of the areas of the two cavities is equal.
For the reversing valve, attention should be paid to satisfying the requirements of the system for automation and operation cycle, and its operation type should be reasonably selected from manual, mechanical, electromagnetic, electro-hydraulic and other types. Correctly select the median function of the spool valve and grasp its transition quasi-state function. For systems that use hydraulic locks (dual hydraulic control check valves) to lock hydraulic actuators, “H” and “Y” shaped spool valves with mid-position functions should be selected so that when the directional valve is in the neutral position, The control chambers of the two hydraulic control check valves are both connected to the oil tank to ensure the reliable reset of the hydraulic control check valve and the good locking state of the hydraulic actuator.
The above small valves are described from four aspects: the selection of directional control valves, the installation and connection methods of hydraulic valves, the rated pressure and flow rate of hydraulic valves, the actual flow rate of hydraulic valves, and various types of valves. After a comprehensive understanding of the precautions for selection, you must have a deeper understanding of the precautions for the selection of hydraulic control valves.