What is the function of superimposed hydraulic control check valve

The superimposed hydraulic control check valve is an important control element in the hydraulic system. It combines the one-way conduction characteristics of the check valve and the reverse opening capability of the hydraulic control function, and simplifies installation and integration through the superimposed design. Its core role can be summarized into the following five aspects, detailed descriptions based on specific application scenarios:

1. Basic functions: One-way conduction and reverse controllable opening
forward flow freely.
When the oil flows from the valve inlet (P) to the oil outlet (A), the valve core automatically opens under the action of oil pressure, the oil can pass without hinderment, and the pressure loss is extremely small (usually ≤0.3MPa).
Application scenario: During the extension stroke of the hydraulic cylinder, oil flows from the pump to the rod-free cavity of the hydraulic cylinder. The superimposed hydraulic control check valve allows the oil to flow freely and drives the piston to move.
Reverse flow hydraulic control is turned on.
When oil is required to flow back from the oil outlet (A) back to the oil inlet (P), the control pressure oil must be passed through the control port (K). After the control pressure overcomes the spring force, the valve core is pushed open to achieve reverse conduction.
Control pressure requirements: Usually 30%-60% of the system working pressure (for example, when the system pressure is 20MPa, the control pressure requires 6-12MPa).
Application scenario: During the retraction stroke of the hydraulic cylinder, pressure oil must be inserted through the control port to open the valve core, so that the oil flows back to the oil tank from the rodless cavity of the hydraulic cylinder.
2. Core function: The principle of 'one-way lock' and 'safety valve'
pressure holding and locking function of hydraulic system
: When the control port (K) is relieved, the valve core is closed under the action of a spring, cutting off the reverse flow path of the oil, so that the hydraulic cylinder or load remains in the current position.
Effect: The system pressure can be maintained for a long time (the holding time depends on the sealing performance, usually for several hours to several days) to prevent the load from falling due to leakage.
Typical application:
crane boom: When lifting heavy objects, the hydraulic control check valve locks the hydraulic cylinder to prevent heavy objects from falling due to oil leakage.
Injection molding machine mold clamping: After the mold is closed, the valve core is closed to maintain the mold clamping force to prevent the mold from opening unexpectedly during high-pressure injection.
Safety protection scenarios to prevent load from falling
: In hydraulic systems with vertical loads (such as lifting platforms, elevators), if the reversing valve leaks or the pipeline breaks, the load may accelerate the sliding due to its own weight.
Function: The superimposed hydraulically controlled check valve can be closed instantly to block the return of oil. Even if the reversing valve fails, it can maintain the load position and avoid safety accidents.
Data support: The sealing performance of high-quality valve cores can ensure that the leakage amount is ≤1ml within 10 minutes under 10MPa pressure, meeting the safety standards requirements.
3. Advantages of superimposed design: Modular and integrated
simplified hydraulic circuit design
structure features: superimposed hydraulic control check valves are directly stacked on the bottom plate or reversing valve through standardized installation surfaces (such as ISO 4401 or DIN 24340), without the need for separate pipeline connections.
Comparative advantages: Compared with traditional pipe connections, the superimposed design can reduce the length of pipes and number of joints by more than 50%, reducing leakage risk (pipe joint leakage accounts for 30%-40% of hydraulic system failures).
Compact space, easy maintenance
and optimization: the superimposed valve body height is usually 80-150mm, and the area covers a small area, which is suitable for machine tools or automation equipment with limited space.
Convenient maintenance: The modular design allows quick replacement of single valve blocks without dismantling the entire hydraulic circuit, and the maintenance time is reduced to 1/3 of the traditional method.
Multifunctional integrated capability
combination application: It can be combined with other superimposed components (such as relief valves, throttle valves, one-way throttle valves) to form a multifunctional valve group to achieve composite functions such as pressure holding, speed regulation, and unloading.
Case: In a hydraulic punch, the superimposed hydraulic control check valve is combined with an overflow valve, which can not only lock the hydraulic cylinder, but also limit the maximum pressure of the system through the relief valve to protect the safety of the equipment.
4. Analysis of typical application scenarios
Hydraulic fixture system
requirements: The fixture needs to quickly clamp the workpiece and maintain clamping force, while allowing rapid release.
Solution: The superimposed hydraulically controlled check valve is combined with the change valve. When clamped, the reversing valve is energized, and the oil flows forward through the check valve to drive the clamp; when loosened, the control port is oiled, the valve core is opened, and the oil is reflowed to achieve rapid release.
Hydraulic motor braking
requirements: The hydraulic motor needs to be braked immediately when it stops to prevent inertia rotation and causing damage to the equipment.
Solution: Install a superimposed hydraulically controlled check valve on the motor oil return circuit to control the pressure relief of the port during braking, and close the valve core and lock the motor to achieve rapid shutdown.
Servo hydraulic system
requirements: The servo valve needs to control the hydraulic cylinder position with high precision while preventing load disturbances from affecting stability.
Solution: The superimposed hydraulic control check valve is used as a 'back pressure valve' to lock the hydraulic cylinder in the neutral position of the servo valve, eliminate position drift, and improve system rigidity.
5. Precautions for selection and use .
Key parameters matching
. Select the diameter of the valve according to the system flow rate (such as 6mm, 10mm, 16mm) to avoid excessive pressure loss or valve core stagnation due to too small diameter.
Pressure level: Ensure that the rated pressure of the valve (such as 16MPa, 31.5MPa) is higher than the maximum operating pressure of the system, and a safety margin of more than 20%.
Control oil circuit design
to control pressure stability: The control port must be equipped with pressure stabilization devices (such as energy accumulators or pressure reducing valves) to avoid pressure fluctuations causing frequent opening and closing of the valve core and shorten its service life.
Response time requirements: In high-speed systems, a valve type with a response time of ≤10ms must be selected to meet the dynamic control needs.
Maintenance and troubleshooting
Common faults:
Internal leaks: cause pressure maintenance failure, and it is necessary to check for wear on the valve core sealing surface or spring fatigue.
Stuck: caused by oil contamination, the filter element needs to be replaced regularly (the filter accuracy is ≤10μm).
Maintenance cycle: It is recommended to check the flexibility of the valve core every 500 hours and replace the seal every 2000 hours. The core functions of
superimposed
hydraulic control check valves through one-way conduction and reverse hydraulic control opening, combined with the modular advantages of superimposed design, realize key roles such as pressure holding, locking, and safety protection in the hydraulic system. Its typical applications cover engineering machinery, machine tools, automation equipment and other fields, and are an important component to improve system reliability and simplify loop design. When selecting the model, focus on parameters such as diameter, pressure level, control response, etc., and regular maintenance is required to ensure long-term and stable operation.