There are many types of solenoid valves. Hydraulic solenoid valves are used in hydraulic control systems, and pneumatic solenoid valves are used in pneumatic control systems. The function of these solenoid valves is to control the flow, pressure, or flow of liquid or gas. Although there are many types of solenoid valves, their structures are all the same. They consist of three main parts. The first part is the valve body of the solenoid valve, the second part is the valve core of the solenoid valve, and the third part is the driving valve core. Electromagnet or spring, its working principle is shown in the figure below.
Pneumatic valves are also important components for controlling the pressure, flow and flow direction of air, so we can divide pneumatic valves into three categories. The first type controls the direction, which we call directional control valves, and the second type regulates pressure. , we call it the pressure control valve, and the third one controls the air flow, we call it the flow control valve.
Solenoid valve identification method
Whether it is a hydraulic valve or a pneumatic valve, their structure is the same, so when talking about solenoid valves, the term “several positions, several channels” is often used, so when we get the solenoid valve , how should we distinguish it? How many positions and channels does the solenoid valve have?
Below is the reversing valve. We assume that when the valve core moves to the right, the pressure output by the hydraulic pump will enter the left chamber of the hydraulic cylinder from the P port of the valve through the A port. At this time, the liquid in the hydraulic cylinder cavity valve will flow back to the tank through port B, causing the piston in the valve to move to the right. Of course, if the spool moves to the left, the flow direction of the liquid will be reversed and the piston will move to the left.
We can draw this reversing valve as a graphical symbol, as shown on the left side of the picture above. Because the valve core of this reversing valve has three working positions relative to the valve body, we generally use a thick solid line frame symbol to represent one working position of the valve. , so there are three boxes, so we call it a three-position valve.
And because the reversing valve has five oil ports P, A, B, T1, and T2, there are five intersection points between the channel representing the liquid and the box in each large box. This type of reversing valve is also called a five-way valve. In this way we can know that the valve is generally judged to be a three-position five-way valve.
From the picture above we can see that the oil port in the middle of the valve is not connected. We usually use a symbol like “T” to indicate that when the valve core moves to the left, it means that the reversing valve is working in the left position. At this time, P, A, B, and T2 are the same. If the valve core moves to the right, it means that the reversing valve is working in the left position. The valve works in the correct position, and P, A, B, and T1 are the same at this time. Through this explanation, we can determine that the valve is a three-position five-way directional valve.
Through the analysis of the oil circuit valve, the judgment of the solenoid valve is also the same. For example, the solenoid valve on the right side of the gas circuit diagram in the figure below can be obtained based on the analysis of the oil circuit valve. It has two large boxes. First, you can determine that it is a two-position solenoid valve, and then see how many air outlets it has. Through observation, we found that there are three air outlets on each square, so we can call this solenoid valve a two-position three-way solenoid valve.
In this way, through the analysis of the two valves, we can draw a conclusion, that is, we must first observe how many boxes there are in the symbol diagram of the solenoid valve, how many boxes represent the number of valves, and then look inside each box There are several inlets and outlets for oil or gas lines, and some are multi-way valves, so we can easily distinguish that the solenoid valve below is a two-position five-way solenoid valve, and its schematic diagram is shown below.
The identification of solenoid valves is mainly based on two points. One is to observe how many air ports the solenoid valve has to determine the number of valves. The other is to judge based on the graphic symbols marked on the nameplate on the solenoid valve body. There are several valves. It is not difficult to distinguish the number of digits and channels of the solenoid valve through the above two steps.