A multi-valve is an integrated hydraulic control component used for centralized control of multiple hydraulic actuators. In hydraulic systems of engineering machinery, agricultural machinery, mining equipment, etc., the multi-valve serves as the core control unit, directing the direction, pressure, and flow of hydraulic oil.

1.Structure and Working Principle of Multi-way Valves

The basic functions of a multi-way valve include:

(1) Directional control:

Changing the flow path of hydraulic oil to control the direction of movement of the actuator, such as the extension and retraction of a cylinder, or the forward and reverse rotation of a motor.

(2) Pressure control:

Limiting the working pressure of the system or branch circuit through built-in safety valves and other devices to prevent system overload and provide safety protection.

(3) Flow control:

Controlling the flow to the actuator by adjusting the valve core opening, thereby regulating the speed of the actuator.

Multi-way valves integrate the functions of multiple directional valves, safety valves, check valves, etc., into a single valve body, achieving compactness and centralized control of the hydraulic system, improving system reliability and operational efficiency.

Basic Structure

A typical multi-way valve mainly consists of the following components:

(1) Valve Body:

The main body of the valve, with complex oil passages cast or machined inside, forming the basic flow path for hydraulic oil.

(2) Valve Core:

The core control component of the multi-way valve, usually a precision-machined cylinder. Its axial movement within the valve body opens or closes different oil ports, realizing the switching of oil circuits.

(3) Operating Mechanism:

The component that drives the movement of the valve core. Depending on the control method, it can be divided into manual levers, hydraulic pistons, or electromagnets.

(4) Safety Valve Assembly:

Includes the main safety valve and overload valve. When the system pressure or the pressure of a certain circuit exceeds the set value, the valve opens to release pressure to protect the system safety.

(5) Auxiliary Valves:

Includes replenishing valves, check valves, etc., used to prevent the actuator from sucking in air, maintain the load, or achieve specific functions such as unidirectional oil flow in the circuit.

Working Principle

The working principle of a multi-way valve is based on the displacement of the valve core within the valve body.

(1) Neutral Position:

When there is no operating signal, all valve cores are in the neutral position. At this time, the hydraulic pump output oil usually flows directly back to the oil tank through the neutral channel of the multi-way valve, the system is in an unloaded state, and energy consumption is low.

(2) Working State:

When the operating mechanism drives the valve core of a certain section to move, the valve core is displaced from the neutral position. This displacement changes the connection relationship of the oil circuit within the valve body:

① The pressure port is connected to the port leading to one chamber of the actuator.

② The port of the other chamber of the actuator is connected to the return port.

③ The pressure oil pushes the actuator to move in one direction, while the return oil flows back to the oil tank.

④ Reversing the valve core operation switches the inlet and return oil paths, causing the actuator to move in the opposite direction.

⑤ The displacement of the valve core is usually proportional to the flow rate through that section, thereby controlling the speed of the actuator.

2. Classification of Multi-way Valves

Multi-way valves can be classified in several ways.

(1) Classification by Valve Core Mid-position Function

Mid-position function refers to the connection method of each port when the valve core is in the middle position. Common types include:

O-type: All ports are closed. The actuator is locked in the current position, and the pump is not unloaded.

H-type: All ports are interconnected. The actuator is in a floating state, and the pump is unloaded.

Y-type: The two chamber ports of the actuator are connected to the return port, and the pressure port is closed. The actuator floats.

P-type: The pressure port is connected to the two chamber ports of the actuator, and the return port is closed. Differential connection can be achieved.

M-type: The pressure port is connected to the return port, and the two chamber ports of the actuator are closed. The pump is unloaded, and the actuator is locked. This is one of the most common forms of mid-position function.

(2) Classification by Operation Method

Manual type: The valve core is directly operated by a mechanical lever or handle. Simple structure, low cost, but requires significant operating force and is difficult to remotely control.

Hydraulic control: The main valve core is moved by pilot pressure oil. Easy to operate, capable of large flow control, and is the mainstream control method for modern large-scale equipment.

Electro-hydraulic proportional control: A proportional electromagnet is controlled by an electrical signal to precisely control the pilot pressure or valve core displacement. Enables precise stepless control and is easy to integrate with automation systems.

(3) Classification by structural form

Integral type: All valve bodies are cast as a single unit. Compact structure, few leakage points, but complex manufacturing process, poor flexibility, and inconvenient maintenance.

Segmented type: Each valve body is an independent module, connected as a whole by bolts. High degree of modularity, the number of units can be increased or decreased as needed, convenient maintenance, and is currently the mainstream structure.

3. Key Technologies and Systems

(1) Load-Sensitive Technology

Load-sensitive technology is an advanced hydraulic control technology designed to improve system efficiency and operational performance. It consists of a load-sensitive pump and a load-sensitive multi-way valve.

Working Principle: The multi-way valve feeds back the highest load pressure signal from each actuator to the hydraulic pump in real time through a load-sensitive feedback oil circuit. Upon receiving this signal, the pump automatically adjusts its output pressure to ensure it is always a constant pressure difference higher than the highest load pressure.

Technical Advantages:

Flow Independence: The speed of the actuator depends only on the valve core opening, independent of load changes, resulting in stable operational performance.

Energy Saving and High Efficiency: The pump’s output pressure is only slightly higher than the load pressure, avoiding unnecessary throttling losses and heat generation.

Coordinated Compound Actions: When multiple actuators operate simultaneously, each circuit can distribute flow according to a predetermined ratio, reducing mutual interference.

(2) Electro-Hydraulic Proportional Technology

The electro-hydraulic proportional multi-way valve achieves precise and continuous control of the valve core displacement by receiving electrical signals from the controller.

Technical Advantages:

Easy to implement remote control and automation.

Enables precise speed regulation and positioning of actuators.

Provides a foundation for intelligent equipment functions such as adaptive operation and power matching.