Structural features of superimposed hydraulic control check valve

The superimposed hydraulic control check valve is a hydraulic component that combines the function of the hydraulic control check valve with the design concept of the superimposed valve. It has the characteristics of compact structure, convenient installation, high integration and flexible control. It is widely used in hydraulic systems where one-way locking, pressure holding or reverse opening is required. The following is a detailed analysis of its structural characteristics:

1. Overall structural characteristics

Overlay design

Modular structure: consists of valve body, control cover plate, spring, valve core, seal and other components. Each functional module (such as one-way valve, control oil circuit) is integrated into one valve body and is installed vertically through a standard mounting surface (such as ISO 4401 or DIN 24340) with other superimposed valves (such as reversing valves, pressure valves).

Installation convenience: No separate pipe is required, it is directly fixed to the bottom plate of the valve group by bolts, reducing leakage points and shortening system assembly time.

Multi-port configuration

Standard ports: Usually, they include oil inlet (P), oil outlet (A), control port (X) and oil drain port (L). Some models may integrate the oil return port (B) of the check valve.

Functional expansion: Composite control function can be achieved by superimposing valve plates with different functions (such as pressure reducing valves and throttle valves).

2. Core component structure

1. Valve body

Materials and technology: It is made of high-strength alloy steel (such as 45# steel) or stainless steel, and is forged, heat-treated and precision-processed to ensure that it does not deform under high pressure.

Oil passage design: The internal oil passage is formed by drilling or casting, and the surface is plated with hard chromium to reduce the corrosion and wear of hydraulic oil.

Sealing structure: O-rings or combined seals (such as Steel seals) are used at the opening to prevent external leakage; tapered or spherical seals are used between the internal valve core and the valve seat to achieve zero leakage.

2. Valve core

Types and structures:

One-way valve core: usually a conical valve or ball valve structure, pressed on the valve seat by spring force to achieve forward cutoff and reverse conduction.

Hydraulic valve core: Add a control piston to the one-way valve core, and push the valve core to open the reverse path by controlling the oil pressure.

Material selection: The valve core is made of high-hard, wear-resistant materials (such as carburized steel or ceramic coating), and the valve seat is made of cemented carbide (such as YG8), which improves the sealing life.

3. Control cover

Functional integration: Integrate control of oil circuits, check valves, throttling orifices and other components to simplify the valve body structure.

Structural features:

Control oil circuit: The control oil port (X) is connected to the hydraulic piston cavity through internal drilling.

Oil drain channel: Independent oil drain port (L) leads the leaking oil from the hydraulic piston chamber back to the oil tank to avoid back pressure affecting the control accuracy.

Adjustable components: Some models are equipped with adjustable flow valves or damping plugs to adjust the response speed of the oil pressure control.

4. Spring assembly

Forward spring: Located behind the one-way valve core, it provides preloading force to ensure reliable sealing when forward cuts.

Reverse spring (optional): Some models add reverse springs after the hydraulically controlled valve core to assist the valve core reset and improve the response speed.

Spring material: High fatigue strength spring steel (such as 60Si2Mn) is used, and is pre-pressed to ensure that it does not deform for a long time.

3. Key structural innovation

Zero-leak seal design

Cone valve seal: The one-way valve core and the valve seat are matched with a 60° cone surface, and the contact stress is evenly distributed, and the sealing pressure can reach 1.5 times the maximum working pressure of the system.

Soft seal compensation: Some models add polytetrafluoroethylene (PTFE) soft seal ring to the sealing surface of the cone valve to compensate for processing errors and achieve slight leakage (≤1 drop/min).

Quick response structure

Lightweight spool: Reduce motion inertia and improve the opening/closing speed (response time ≤10ms) by optimizing the shape of the spool (such as streamlined head) and material (such as aluminum alloy).

Pilot control: adopts a two-stage control structure (such as pilot valve + main valve), and drives a large flow main valve through small flow control oil to reduce the control pressure requirement.

Anti-pollution design

Large flow filter: Integrate a 100μm filter at the control oil port (X) inlet to intercept particulate pollutants and prevent valve core from being stuck.

Wear-resistant coating: hard chromium is plated on the valve core surface or sprayed with tungsten carbide to improve wear resistance and extend service life.

IV. Typical structure examples

Taking a brand of superimposed hydraulic control check valve as an example:

Valve body: Hexahedral structure, with upper and lower mounting surfaces, front and back oil ports, and left and right oil circuit interfaces.

Spool assembly:

Forward direction: conical valve core + spring, sealing pressure ≥31.5MPa.

Reverse: hydraulically controlled piston + conical valve core, opening pressure ≤0.5MPa (control oil pressure).

Control cover plate: Integrated check valve and throttle hole, the diameter of the throttle hole φ0.8mm can be adjusted to control oil response speed.

Seals: All dynamic seals are made of St. seals, and the static seals are made of O-rings, with working temperature range of -30℃~+120℃.