The Working Principle And common Faults of Solenoid Valves

The solenoid valve is an industrial device that is controlled by electromagnetic force. It is an automatic basic component used to control fluids. It is an actuator; it is not limited to hydraulic and pneumatic. It is widely used in our daily life. First of all, we have a preliminary understanding of the solenoid valve. The solenoid valve is composed of a solenoid coil and a magnetic core. It is a valve body containing one or several holes. When the coil is energized or de-energized, the operation of the core will cause fluid to pass through the valve body or be severed to achieve the purpose of changing the direction of the fluid.

Solenoid valve working principle: There are closed chambers in the solenoid valve. There are through holes in different positions. Each hole leads to different oil pipes. The middle of the cavity is a valve. On both sides are two electromagnets. Which side of the magnet coil is energized? The body will be attracted to which side, by controlling the movement of the valve body to block or leak different oil drain holes, and the oil inlet hole is normally open, the hydraulic oil will enter different oil drain pipes, and then through the oil The pressure pushes the piston of the cylinder, which in turn drives the piston rod, which moves the mechanical device. This controls the mechanical motion by controlling the current of the electromagnet.
Solenoid valves are divided into three categories according to the principle: direct-acting type, distributed direct-acting type and pilot-type type; according to the structure, they are divided into diaphragm type solenoid valve and piston type solenoid valve.

The failure of the solenoid valve will directly affect the action of the switching valve and the regulating valve. For common faults, the solenoid valve does not operate. The following four aspects should be checked:

(1) Air leakage: Air leakage will cause insufficient air pressure, which makes the forced valve open and close difficult. The reason is that the gasket is damaged or the spool is worn out, causing several cavity helium. When dealing with the solenoid valve failure of the switching system, the appropriate timing should be selected, and the solenoid valve should be processed when the power is lost. If the processing is not completed within one switching gap, the switching system can be suspended and taken care of.

(2) The solenoid valve is stuck: the clearance between the sliding valve sleeve and the valve core of the solenoid valve is very small (less than 0.008 mm), and it is generally a one-piece assembly. When mechanical impurities are introduced or the lubricating oil is too small, it is easy to card. live. The treatment method can use a steel wire to break in from the small hole of the head to make it bounce back. The fundamental solution is to remove the solenoid valve, take out the valve plug and the valve core sleeve, and clean it with CCI4, so that the valve core can move flexibly in the valve sleeve. When disassembling, pay attention to the assembly sequence of each component and the external wiring position, so as to reassemble and wire correctly, and check whether the oil mist injection hole is blocked and the lubricating oil is sufficient.

(3) The solenoid valve terminal is loose or the wire head is off, the solenoid valve is not allowed to be energized, and the wire end can be tightened.

(4) When the solenoid valve coil is burnt out, the wiring of the solenoid valve can be removed and measured with a multimeter. If the circuit is open, the solenoid valve coil is burned out. The reason is that the coil is damp, causing poor insulation and magnetic leakage, causing the current in the coil to be too large and burning, so it is necessary to prevent rainwater from entering the solenoid valve. In addition, the spring is too hard, the reaction force is too large, the number of turns of the coil is too small, and the suction force is insufficient to cause the coil to burn. During emergency handling, the manual button on the coil can be turned from the “0” position to the “1” position during normal operation, so that the valve opens.