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What is a Solenoid Valve?

Solenoid valves are the basic components of automation used to control fluids and belong to actuators: not limited to hydraulics and pneumatics. To control the direction of hydraulic flow, the mechanical devices of the factory are generally controlled by hydraulic steel, so solenoid valves are used.
The working principle of the solenoid valve: there is a closed cavity in the solenoid valve, and there are through holes in different positions. Each hole leads to a different oil pipe. There is a valve in the middle of the cavity, and two electromagnets on both sides. When the valve body is energized, it will be attracted to which side. The valve blocks or leaks different oil discharge holes by controlling the movement of the valve body, and the oil inlet hole is normally open, and the hydraulic oil will enter different oil discharge pipes, and then The piston of the oil is pushed by the pressure of the oil, the piston drives the piston rod, and the piston rod drives the mechanical device to move. In this way, the mechanical movement is controlled by controlling the current of the electromagnet. Looking at the solenoid valves at home and abroad, so far, they can be divided into three categories from the action mode: direct-acting, recoil, and pilot.

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Direct-acting solenoid valve

Principle: When the normally closed direct-acting solenoid valve is energized, the solenoid coil generates electromagnetic suction to lift the valve core, so that the closing part is far away from the valve seat and the sealing pair is opened: when the power is off, the electromagnetic force disappears, and the closing element is pressed by the spring force. The valve is closed on the seat. (Normally open is the opposite of this)
Features: It can work normally in a vacuum, under negative pressure, and with zero differential pressure. It can be installed arbitrarily below DN50, but the volume of the electromagnetic head is large. For example, the Yanmar 119515 engine introduced by our company is applicable.

Step-by-step direct acting solenoid valve

Principle: Its principle is a combination of direct action and pilot. When energized, the solenoid valve first opens the auxiliary valve, the pressure in the lower chamber of the main valve is greater than the pressure in the upper chamber, and the valve is opened by the simultaneous action of the differential pressure and the electromagnetic network; When electrified, the auxiliary valve uses the spring force or the medium force to push the closing member and moves the toilet door down to close.
Features: It can work reliably even at zero pressure difference or high pressure, but the power and volume are large and require vertical installation.

Pilot operated solenoid valve

Principle: When the power is turned on, the electromagnetic force drives the pilot valve to open the pilot valve, the pressure in the upper chamber of the main valve drops rapidly, and a pressure difference is formed in the upper and lower chambers of the main valve. The spring force closes the pilot valve, and the inlet medium pressure quickly enters the upper chamber of the main valve through the pilot hole to form a pressure difference in the upper chamber, thereby closing the main valve.
Features: Small size, low power, but the medium pressure difference range is properly limited, and the pressure difference conditions must be met.
Matters needing attention in the selection of solenoid valves

Solenoid valve reliability

Solenoid valves are divided into two types: normally closed and normally open: normally closed type is generally used, which is opened when energized, and closed when power is off; The life test is generally a type test project in the factory. To be precise, there is no professional standard for solenoid valves in my country, so be careful when choosing solenoid valve manufacturers. When the action time is very short and the frequency is high, the direct-acting type is generally selected, and the fast-acting series is selected for large diameters. If you need such a safe and high-quality electromagnetic, you can choose LandTopMall, not only that, we also provide various accessories such as Yanmar 4tnv98 engine parts for you to choose.

Solenoid Valve Safety

Generally, the solenoid valve is not waterproof. If the conditions do not allow it, please choose the waterproof type. The factory can customize it. The highest-rated nominal pressure of the solenoid valve must exceed the highest pressure in the pipeline, otherwise, the service life will be shortened or other unexpected situations will occur. All stainless steel types should be used for corrosive liquid, and a plastic king (SLF) solenoid valve should be used for strong corrosive fluid. Explosive environments must use appropriate explosion-proof products.


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