Working principle of superimposed hydraulic control check valve

The superimposed hydraulic control check valve is a hydraulic component that realizes the reverse flow of the check valve by controlling the fluid pressure. Its working principle and characteristics are as follows:

1. Core structure

The superimposed hydraulically controlled check valve is mainly composed of the following components:

Steel valve body: As the main structure, it provides installation and connection foundation.

One-way valve assembly: Contains one or two check valves (such as check valves 2 and 3) to ensure one-way flow of oil.

Pilot piston: The piston moves by controlling the oil circuit pressure to enable the opening or closing of the check valve.

Pilot cone valve core: located in the main valve core of the one-way valve to ensure the accurate opening of the one-way valve and improve sealing.

2. Working principle

Forward flow (free circulation)

When oil flows from the oil inlet (such as A1) to the oil outlet (such as A2), the check-way valve 2 opens automatically under the action of oil pressure and the oil passes freely. At this time, the pilot piston 4 is pushed to the right position, and the one-way valve 3 is also opened simultaneously through the action of the pilot cone valve core 5 to ensure the smooth flow of the oil circuit.

Reverse flow (control flow)

When the oil is required to flow in reverse (such as from A2 to A1), pressure oil must be input through the control oil circuit. The pressure oil pushes the pilot piston 4 to move, overcomes the spring force, pushes open the check valve core (such as the check valve 3), releases the seal, and causes the oil to flow in reverse. At this time, the check valve 2 may remain closed due to pressure balance or control, or achieve bidirectional flow in conjunction with the check valve 3 .

Pressure maintenance and closure

When the oil inlets A1 and B1 are out of pressure, the spring force presses the valve core tightly on the valve seat, cutting off the oil path between the check valve and the actuator to prevent the oil from flowing backwards. This feature makes it useful for hydraulic systems' pressure holding and locking functions.

3. Control oil circuit type

The oil control circuit of the superimposed hydraulic control check valve is flexible, and common types include:

Oil circuit control: Opening of the check valve through port A pressure control.

Oil B circuit control: Opening of the check valve through port B pressure control.

AB parallel oil circuit (dual hydraulic control): commonly known as 'hydraulic lock'. When the oil of one check valve flows forward, the oil of another check valve flows backward, and there is no need to add a control oil circuit. When there is no pressure oil on ports A and B, the valve cores of the left and right check valves close the oil circuit under the action of spring force to achieve pressure-keeping locking in the two chambers of the hydraulic cylinder.

4. Key design details

Y-type functional reversing valve fit: To ensure that the cone valve is in place correctly, a Y-type functional reversing valve is required to enable the oil tank to be connected to the oil tank when the piston is in the middle to avoid residual pressure affecting the sealing property.

Materials and Process: The valve body is made of high-strength steel, and the valve core and valve seat are precision polished to ensure sealing and wear resistance.

Modular design: The superimposed structure allows it to be directly superimposed with other hydraulic valves (such as reversing valves and pressure reducing valves), simplifying hydraulic system design and saving space.

V. Typical application scenarios

Hydraulic cylinder support: In a vertical hydraulic cylinder, prevent the piston and piston rod from sliding down due to leakage of slide valves or pipes.

Pressure holding circuit: Use the tight sealing of the cone valve to achieve long-term pressure holding of the hydraulic system.

Bidirectional locking: Through the combination of dual hydraulic control check valves, the oil in both chambers of the hydraulic cylinder is strictly sealed to prevent the piston from moving due to external forces.

Large flow oil discharge: When the hydraulic cylinder piston is returned, the right chamber oil is quickly discharged through the hydraulic control check valve to avoid throttling restrictions.

Oil filling valve: Compensate for the vacuum suction caused by negative pressure during the high-speed descent of the vertical hydraulic cylinder.