Solenoid valve working principle and classification

Solenoid valve is an automation basic element used to control fluid and belongs to actuator; it is not limited to hydraulic and pneumatic. Solenoid valves are used to control the direction of hydraulic flow. Plant machinery is generally controlled by hydraulic steel, so solenoid valves are used. Working principle: There are sealed chambers in the solenoid valve. There are through holes in different positions. Each hole leads to a different tubing. The middle of the chamber is a valve. The two sides are two electromagnets. Which side of the magnet coil energizes the valve body. Which side will be attracted, by controlling the movement of the valve body to block or leak out different oil discharge holes, and the oil inlet hole is normally open, the hydraulic oil will enter different drain pipes, and then pass through the oil pressure To promote the piston of oil, the piston also drives the piston rod, which drives the mechanical device to move. This controls the mechanical motion by controlling the electromagnet current.

classification:

1 direct-acting solenoid valve

Principle: When the power is turned on, the electromagnetic coil generates an electromagnetic force to lift the closing member from the valve seat and the valve opens. When the power is turned off, the electromagnetic force disappears. The spring presses the closing member against the valve seat and the valve closes.

Features: It can work normally under vacuum, negative pressure and zero pressure, but the diameter generally does not exceed 25mm.

2 distributed direct acting solenoid valve

Principle: It is a combination of direct acting and pilot type. When there is no pressure difference between the inlet and the outlet, the electromagnetic force directly lifts the pilot small valve and the main valve closing part and the valve opens. When the inlet and outlet reach the starting differential pressure, after the power is turned on, the electromagnetic force leads the small valve, the pressure in the lower chamber of the main valve rises, and the pressure in the upper chamber decreases, thereby pushing the main valve upwards by utilizing the pressure difference; when the power is off, the pilot valve utilizes the spring. Force or medium pressure pushes the closure and moves it downwards to close the valve.

Features: In the zero pressure difference or vacuum, high pressure can also be * action, but the power is relatively large, requires a horizontal installation.

3 pilot solenoid valve

Principle: When the power is turned on, the electromagnetic force opens the pilot hole, the pressure in the upper chamber drops rapidly, and a pressure difference between the lower part and the upper part is formed around the closing part. The fluid pressure pushes the closing part to move upwards and the valve opens; when the power is turned off, the spring force leads the pilot. The hole is closed and the inlet pressure quickly bypasses the chamber to form a lower, upper high pressure differential around the valve closing member. The fluid pressure pushes the closing member downward and closes the valve.

Features: The upper limit of the fluid pressure range is high and can be installed arbitrarily (customization is required) but the fluid pressure difference must be met. In use, it should consider some of its characteristics, such as the characteristics of the media, ambient temperature, operating frequency, power and other factors.

Electromagnetic valves at home and abroad are divided into three major categories (ie, direct-acting, step-by-step, and pilot-type), and the difference between the valve structure and material and the principle is divided into six. Sub-categories (straight-acting diaphragm structure, step-by-step structure, pilot diaphragm structure, direct-acting piston structure, step-by-step direct-acting piston structure, pilot piston structure).