What is the working principle of a solenoid valve? Once you understand it, you will no longer be afraid of solenoid valve malfunctions.

From the diagram below, we can see that these solenoid directional valves are bundled into a single unit, and the air inlets and outlets of each valve inside are interconnected. We call this dual-coil solenoid valve and single-coil solenoid valve a valve group. When connecting the air circuits, only one air supply tube is needed to connect to the inlet.

The coil of the electromagnetic directional valve has two wires: one is a red wire, which is connected to the positive pole of a 24V DC power supply, and the other is a blue wire, connected to the negative pole of the DC power supply. The red indicator light inside the solenoid valve has a positive and negative polarity. If the wires are reversed, the indicator light of the solenoid valve will not turn on, but it can still operate the valve. In a real control circuit, the solenoid valve can be controlled by various relays, or it can be controlled using the output terminals of a PLC.

Solenoid valves can be divided into one-way solenoid valves and two-way solenoid valves. A one-way solenoid valve is used to control a cylinder's movement in a single direction, enabling the cylinder to extend and retract. A two-way solenoid valve can control the cylinder's air intake and exhaust, thereby enabling the cylinder to extend and retract. On a sorting mechanism production line, the solenoid valves used for pneumatic manipulators are two-way, while the solenoid valves used to sort materials on the conveyor belt are one-way.

The difference between a one-way solenoid valve and a two-way solenoid valve is that the initial position of a two-way solenoid valve is arbitrary, and it can freely control two positions. The initial position of a one-way solenoid valve is fixed, and it can only control one direction.