Hydraulic Directional Valves

Hydraulic directional valve has accurate action, high degree of automation, stable and reliable work, and is widely used in petroleum, chemical, mining and metallurgical industries.

The main performance of hydraulic directional valves

1. Work reliability

It refers to whether the electromagnet can be reliably commutated after power-on, and whether it can be reliably reset after power-off. Solenoid valves can only work normally within a certain flow and pressure range. The limit of this operating range is called the commutation limit.

2. Pressure loss

Due to the small opening of the solenoid valve, a large pressure loss occurs when the liquid flows through the valve port.

3. Internal leakage

In different working positions, under the specified working pressure, the leakage from the high-pressure cavity to the low-pressure cavity is the internal leakage amount. Excessive internal leakage will not only reduce the efficiency of the system, but also cause overheating. It will also affect the normal operation of the implementing agencies.

4. Commutation and reset time

The reversing time of the AC solenoid valve is generally 0.03~0.05s, and the reversing impact is large: while the reversing time of the DC solenoid valve is 0.1~0.3s, the reversing impact is small. Usually the reset time is slightly longer than the commutation time.

5. Commutation frequency

The reversing frequency is the number of reversing times the valve is allowed per unit time. At present, the reversing frequency of the solenoid valve of the solenoid is generally 60 times/min.

6. Service life

The service life of solenoid valves depends mainly on the solenoid. Wet electromagnets have a longer life than dry ones, and DC electromagnets have a longer life than AC ones.

7. Hydraulic clamping phenomenon of spool valve

The hydraulic clamping phenomenon of the spool valve is not only in the reversing valve, other hydraulic valves are also prevalent, more prominent in the high-pressure system, especially the longer the residence time of the spool valve, the greater the hydraulic clamping force, so that the thrust of the mobile spool valve (such as solenoid thrust) can not overcome the clamping resistance, so that the spool valve can not be reset. The reasons for hydraulic clamping are that it is difficult for the valve core to move due to dirt entering the gap, and some are due to the small gap and the valve core expands and jams when the oil temperature rises, but the main reason is the radial unbalanced fluid pressure caused by the geometry error and concentricity change of the spool valve. In order to reduce the radial unbalanced force, the manufacturing accuracy of the valve core and the valve bore should be strictly controlled, and when assembling, it should be made into a conical form as much as possible, on the other hand, the annular equalization groove is opened on the cutting core, which can also greatly reduce the radial unbalanced force.

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