There are many types of hydraulic control valves, which can be divided into the highest pressure of the system and the actual flow through the valve according to different characteristics, and consider the control characteristics, stability and oil port size of the valve, overall size, equipment connection method, Operation methods, etc., are selected from product samples or catalogues. The selection of various hydraulic control valves in the hydraulic system from the factory is as follows:
The actual flow of the hydraulic valve is related to the series and parallel connection of the oil circuit: the flow of the series oil circuit is equal; the flow of the parallel oil circuit working together is equal to the sum of the flow of each oil circuit. In addition, regarding the selection of a single-piston rod hydraulic cylinder system, pay attention to the difference in the oil return flow rate when the piston is extended and retracted: the ratio of the oil return flow rate of the rod cavity when the piston is retracted and the oil return flow rate of the rod chamber when the piston is extended is the same as the ratio of the areas of the two chambers is equal.
The rated pressure and rated flow of each hydraulic control valve should generally be close to its operating pressure and flow. For systems with higher reliability requirements, the rated pressure of the valve should be much higher than its operating pressure. If the rated pressure and rated flow are less than the operating pressure and flow, it is easy to cause hydraulic clamping and hydraulic power and adversely affect the working quality of the valve; for the sequence valve and pressure reducing valve in the hydraulic system, the flow through the valve should not be much less than Rated flow rate, otherwise oscillation or other unstable phenomena are likely to occur. Regarding the flow valve, attention should be paid to its minimum steady flow.
Since the equipment connection method of the valve has a decisive influence on the structure type of the hydraulic equipment planned in the future, it is necessary to know the integration method of the hydraulic control equipment when selecting the hydraulic valve. For example, a plate type hydraulic connection valve is selected, because the valve can be installed on the oil circuit board or oil circuit block, which is convenient for system integration and rationalization of hydraulic equipment planning. ; For example, if a stack valve is selected, it is necessary to study the series spectrum of the stack valve for selection according to pressure and flow, and so on.
Regarding the general directional valve in hydraulic system with simple structure, we should firstly pay attention to the reasonable selection of its opening pressure; the lower opening pressure can reduce the resistance of the liquid flow through the hydraulic directional valve; however, for the hydraulic directional valve used as a back pressure valve , its opening pressure is generally high to ensure sufficient back pressure. Regarding the hydraulic control check valve, in order to avoid abnormal oscillation and noise of the system, attention should also be paid to the reasonable selection of its hydraulic method: when there is back pressure at the outlet of the hydraulic control check valve, the external leakage type should be used, and the internal leakage type can be used in other cases.
Regarding the reversing valve, attention should be paid to the requirements of the hydraulic system for automation and operation cycle, and its operation mode should be reasonably selected from manual, motor, electromagnetic, electro-hydraulic and other types.