Directional valve working principle


With the development of the economy, directional valves are more and more widely used in our daily life, so do you know what is a directional valve? How does it work? Let's find out together!


The directional valve is a directional control valve with more than two flow forms and more than two oil ports, which is a valve that realizes the communication, shut-off and reversing of hydraulic oil flow, as well as pressure unloading and sequential action control, and is a directional control valve by the relative movement of the valve core and the valve body. The directional valve mainly has two types: rotary valve type and spool valve type, which are divided into two positions and three positions according to the number of working positions where the valve core stays in the valve body; According to the number of oil circuits connected to the valve body, it is divided into two-way, three-way, four-way and six-way; The way to operate the movement of the valve spool is manual, motorized, electric, hydraulic, electro-hydraulic and other forms.


1. Manual directional valve

The operation mode of manual reversing valve is the handle, using the lever principle to push the valve core in the valve body to do movement to achieve reversing, when the handle is pulled to the left, the pressure oil port P communicates with A, the pressure oil enters the actuator, and the return oil of the actuator enters port B and flows back to the oil tank from port T; Pull the handle to the right, P through B, A through T, and the actuator will move in the opposite direction.


2. Motorized directional valve

The motorized directional valve is also called the stroke directional valve, and when the retaining iron or cam movement on the actuator touches the spool of the travel directional valve, the internal oil circuit of the directional valve is changed to achieve reversing.


3. Hydraulic directional valve

Hydraulic directional valve is to control the oil acting on the valve core, when the control oil is pressured to control the directional valve reversing, hydraulic directional valve is usually used in conjunction with other directional valves. When there is no pressure oil, the spring acts on the far left of the spool; When there is pressure oil, the spool moves to the right.


4. Electro-hydraulic directional valve

The electro-hydraulic directional valve is energized through the windings of the two solenoid valves, so that the balance hole circuit is closed, the discharge hole circuit is opened, the upper cavity of the piston releases pressure, the piston rises, and the valve body is opened. Conversely, the piston descends and the valve body closes. In the process of opening and closing the valve, the flow rate signal and the valve plug position signal can be transmitted to the computer, and after processing by the computer, the corresponding command is issued to change the hydraulic difference between the upper and lower chambers of the piston through the energized and off-state of the two solenoid pilot valves, so as to control the piston at the required opening height and achieve the purpose of controlling the flow of pipeline medium.


5. Electromagnetic directional valve

There are many types of solenoid valves, but they work on roughly the same principle. The electromagnetic directional valve is mainly composed of valve body, valve core, spring, armature and solenoid coil. After the electromagnetic power is turned on, the direction, flow, speed and other parameters of the fluid medium such as gas and liquid can be controlled. The valve body of the electromagnetic directional valve has a closed cavity, according to the actual needs, will be in different positions of the cavity to open holes and communicate with the outside world, each hole will be connected to the corresponding pipeline, in the middle of the cavity to install a valve core, the valve core will be connected with the armature, both sides are installed with solenoids and springs, which side of the solenoid coil is energized will produce a certain electromagnetic force, when this electromagnetic force exceeds the spring of the spring, it will attract the valve core, through the movement of the valve core to control the opening or closing of the outer hole. When the solenoid coil is energized or powered off, the valve core will move left and right, and the spring plays a certain buffer role during the movement process to prevent the valve core from having too much impact on the valve body.


The above is the working principle of several directional valves, hope it will help you, if you have any interest or doubts about the topic, welcome to contact us!



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