The reversing valve is a valve that changes the direction of movement of the actuator by changing the direction of oil flow. There are many types of reversing valves. Generally, they can be divided into manual reversing valves, motorized reversing valves, electromagnetic reversing valves, hydraulic reversing valves, and electro-hydraulic reversing valves according to different control methods. This article will briefly introduce the principles of these types of reversing valves.
1. Hydraulic reversing valve
This is the Directional Control Valve mainly provided by HANJIU. The hydraulic reversing valve is based on the control oil acting on the valve core, and when the control oil is under pressure, the reversing valve is controlled to change direction. Hydraulic reversing valves are usually used in conjunction with other reversing valves. As shown in the figure, when there is no pressure oil, the spring acts on the spool on the leftmost side, P to B and A to T; when there is pressure oil, the spool moves to the right so that the P, T, A, and B ports are all blocked.
2. Manual reversing valve
The operation mode of the manual reversing valve is the handle, which uses the principle of lever to push the valve core to move in the valve body to realize the reversal. When the handle is pulled to the left, the pressure oil P communicates with port A, the pressure oil enters the actuator, and the return oil of the actuator enters port B and flows back to the tank from port T; pull the handle to the right, P through B, A through T , The actuator will move in the opposite direction.
3. Motorized reversing valve
The motorized reversing valve is also called the stroke reversing valve. When the spool of the stroke reversing valve is touched by the stopper or cam movement on the actuator, the internal oil circuit of the reversing valve is changed to realize the reversal.
4. Electromagnetic reversing valve
The operation mode of the electromagnetic reversing valve is the attraction of the electromagnet. The spool is pushed to move in the valve body by the attraction of the armature after the electromagnet is energized, and the spool is reset by the spring after the power is cut off. The picture shows the Rexroth 4WE solenoid directional valve, which is a three-position four-way valve. When the electromagnet on the left is energized, push the spool to move to the right, P is connected to B, and A is connected to T; the electromagnet on the right is energized, P is connected to A, and B is connected to T.
5. Electro-hydraulic directional valve
The electro-hydraulic directional valve is suitable for large flow occasions, because the thrust provided by the electromagnet is limited. When the flow is large, the electromagnet will not be able to push the spool, while the electro-hydraulic directional valve is an electromagnetic reversing valve. The valve is used as the pilot valve, and the hydraulic control valve is used as the main valve. Through the reversing of the electromagnetic reversing valve, the flow direction of the control oil is changed, so that the main valve can realize reversing under the action of the control oil.
The upper end is the electromagnetic reversing valve as the pilot valve, and the lower end is the hydraulic reversing valve as the main valve. The two oil outlets of the pilot valve act on both sides of the spool of the main valve. The figure shows the form of external control leakage. The control oil X of the pilot valve is introduced from the outside and does not communicate with the main oil circuit; the oil return Y of the pilot valve is returned to the oil tank separately. When the electromagnet on the left is energized, the pilot spool moves to the right, and the control oil X enters the right side of the main spool, pushing the main spool to move to the left, so that the main oil circuit P is connected to A and B is connected to T; otherwise, the right solenoid When energized, P is connected to B and A is connected to T.