Cartridge Pressure Relief Check Valve DLF08-00

I. Definition and Core Functions

Definition: The cartridge type pressure relief check valve is a composite valve with a cartridge unit as the main body, integrating a pressure relief valve (overflow function) and a check valve (unidirectional flow). It is installed by inserting it into the prefabricated hole of the hydraulic valve block and cooperating with the control cover plate.
Core functions:
Pressure relief protection: When the system pressure exceeds the set value, the overflow will be automatically activated to prevent damage to components due to excessive pressure.
Check control: It allows the oil to flow in one direction, prevents reverse flow, and avoids pressure fluctuations in the system or loss of control of the actuator.

Ii. Structure and Working Principle
1. Basic structure

Plug-in unit main body
Valve core: It is usually of a cone valve structure, with an oil flow channel at the bottom and a control chamber (C chamber) at the top.
Spring: Provides the reset force and sets the pressure relief opening pressure (the stiffness of the spring determines the pressure relief value).
Valve sleeve: It is equipped with oil inlet and outlet ports (cavity A and cavity B) and sealing grooves. After being inserted into the valve block, it forms an oil circuit connection.
Control cover plate: Integrates check valve assembly (check valve core or seat) and pressure relief control oil circuit. Some models include damping holes or pilot interfaces.
Check function component: A check valve structure (such as a ball valve or cone valve) is set inside the cover plate or cartridge unit to achieve unidirectional flow of oil.

2. Working Principle

Check pattern (positive flow) :
When the oil flows from chamber A to chamber B, the pressure pushes the check valve assembly to open (or directly lifts the cartridge valve core), and the oil passes through smoothly. If the pressure in Chamber B is higher than that in chamber A, the check valve assembly closes to prevent the reverse flow of the oil.
Pressure relief mode:
When the pressure in Chamber A (or the main oil circuit of the system) exceeds the set value of the spring, the cartridge valve core overcomes the spring force and moves upward. Chamber A is connected to the return oil port (Chamber T), and the oil overflows back to the oil tank, maintaining the system pressure at the set value. After the pressure drops, the valve core returns to its original position under the action of the spring and stops overflowing.

Iii. Functional Features and Classification
Core features

Integrated composite functions: One valve simultaneously achieves pressure relief and check, reducing the installation space of valve blocks and pipeline connections.
Fast response speed: The cartridge structure valve core has a short stroke. When the pressure exceeds the limit, it can open for pressure relief within 5 to 10ms.
Flexible pressure setting: By replacing springs of different stiffness or installing a pilot valve, the pressure relief can be adjusted (the range is usually 10 to 40MPa).
Strong anti-pollution ability: The sealing surface of the cone valve is not easily jammed by impurities, making it suitable for hydraulic systems with a high degree of contamination.