What is the working principle of 4WEH16 electro-hydraulic reversing valve?

4WEH16 electro-hydraulic reversing valve is a combination device of an electromagnetic reversing valve and a hydraulically controlled reversing valve. The pilot oil circuit is controlled through the solenoid valve, and the main valve core is driven to move, realizing the switching of the direction of large flow liquid flow. Its working principle can be divided into the following steps:

1. Structural composition

Pilot solenoid valve: As a control unit, it is usually a two-position four-way or three-position four-way solenoid valve, and the valve core position is changed by energizing/disconnecting the solenoid.

Main valve: Hydraulic reversing valve, with control chambers at both ends of the valve core, which pushes the valve core to move through pressure oil.

Control oil circuit: includes two methods: internal oil supply (take oil from port P of the main valve) and external oil supply (through independent oil circuit). The return oil is returned to the oil tank through port T or port Y.

2. Median state (both electromagnets are powered off)

Pilot valve status: The valve core is in the middle position under the action of the centering spring, and the oil supply to the main valve control chamber is cut off.

Main valve status:

The pressure oil of the control chamber is returned to the oil tank through the T-port of the pilot valve, and the pressures at both ends of the main valve core are equal.

The main valve core remains in the middle position under the action of the centering spring, the oil ports of P, A, B and T are blocked, and the actuator is stopped.

3. Commutation process (one-side solenoid is energized)

Take the electromagnet on the left as an example:

Pilot valve action:

The solenoid on the left pushes the valve core to move the right, and the pressure oil on the port P enters the control chamber at the right end of the main valve through the pilot valve.

The oil in the left end of the main valve returns to the oil tank through the pilot valve, and the pressure is reduced.

Main valve core movement:

The pressure of the right end control chamber increases, pushing the main valve core to move to the left.

After the main valve core moves, port P and port A are in communication, port B and port T are in communication, and the actuator moves forward.

steady state:

After the main valve core is moved to the new position, the pressure of the control chamber at both ends is rebalanced, and the valve core is stable at this position.

When the electromagnet on the right is energized, the process is opposite: port P and port B are connected, port A and port T are connected, and the actuator moves in reverse.

4. Key Features

Large flow control: The main valve core is driven by the pilot oil circuit, and a small flow solenoid valve is needed to control the large flow flow.

Buffer function: The movement speed of the main valve core can be adjusted by a one-way throttle valve to avoid reversing impact.

Reset method:

Spring centering: The main valve core relies on the spring force to return to the middle position.

Hydraulic centering: Maintaining the central position through pressure oil balance, suitable for high-pressure systems.

Control method: Supports internal control (oil supply from the main valve port P) and external control (oil supply from the independent oil circuit) to meet different system needs.

5. Application scenarios

4WEH16 electro-hydraulic reversing valve is widely used in high flow hydraulic systems, such as:

Construction machinery (cranes, excavators)

Industrial equipment (died casting machine, injection molding machine)

Metallurgical machinery (rolling mill, continuous casting machine)