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The hydraulic control check valve is a valve that can reverse the flow of the check valve by controlling the fluid pressure. This kind of valve occupies an important position in the hydraulic support equipment of coal mining machinery. The difference between the hydraulic control check valve and the ordinary check valve is that there is an additional control oil circuit. When the control oil circuit is not connected to the pressure oil, the hydraulic control check valve works like an ordinary check valve, and the pressure oil only Flow from inlet to outlet, not reverse flow. When the control oil circuit has control pressure input, the piston top rod moves to the right under the action of the pressure oil, and the one-way valve is opened by the top rod to connect the oil inlet and outlet. If the oil outlet is larger than the oil inlet, the oil can flow in the opposite direction.
The difference between hydraulic control check valve and ordinary check valve
1. The effect is different
Ordinary one-way valve is also known as check valve, its function is to control the flow of oil in one direction, and cut off when it is reversed.
Hydraulic check valve:
(1) Keep the pressure.
The spool type reversing valve has gap leakage and can only maintain pressure for a short time. When there is a pressure maintenance requirement, a hydraulic control check valve can be added to the oil circuit, and the tightness of the poppet valve can be used to keep the oil circuit pressure for a long time.
(2) The “support” of the hydraulic cylinder.
In a vertical hydraulic cylinder, due to the leakage of the spool valve and pipe, the piston and piston rod may slide down under the gravity of the piston and piston rod. Connecting the hydraulic control check valve to the oil circuit of the lower chamber of the hydraulic cylinder can prevent the movable parts such as the piston and the slider of the hydraulic cylinder from sliding down.
2. The structure is different
The difference between the hydraulic control check valve and the ordinary check valve is that there is an additional control oil circuit. When the control oil circuit is not connected to the pressure oil, the hydraulic control check valve works like an ordinary check valve, and the pressure oil only Flow from inlet to outlet, not reverse flow.
Field practice has proved that the hydraulic control check valve is prone to problems during the use and maintenance process. The following are the precautions.
(1) It must be ensured that the hydraulic control check valve has sufficient control pressure, and the control pressure is absolutely not allowed to lose pressure. Attention should be paid to whether the control pressure meets the requirements for reverse opening. If the control of the hydraulic control check valve is led to the main system, the influence of the change of the main system pressure on the control oil circuit pressure should be analyzed to avoid the malfunction of the hydraulic control check valve.
(2) According to the position of the hydraulic control check valve in the hydraulic system or the liquid flow resistance (back pressure) after the reverse oil outlet, the structure of the hydraulic control check valve (simple or double) and the oil drain should be reasonably selected. method (internal or external). For the internal leakage hydraulic control check valve, when the reverse oil outlet pressure exceeds a certain value, the hydraulic control part will lose control, so the internal leakage hydraulic control check valve is generally used for the reverse oil outlet cavity without back The hydraulic control check valve can be used in the occasions where the back pressure of the reverse oil outlet is relatively high, so as to reduce the smaller control pressure and save the control power.If the system adopts the internal unloading type, the plunger cylinder will drop intermittently to emit vibration and noise.
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