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Hello everyone, I am Rose. Today I will introduce solenoid valve to you. A solenoid valve is a control device that uses the electromagnetic force generated by an electromagnetic coil to open or close the control fluid valve. In the pipeline control process, it is one of the most widely utilized actuators.
A solenoid valve is a control device that uses the electromagnetic force generated by an electromagnetic coil to open or close the control fluid valve. In the pipeline control process, it is one of the most widely utilized actuators. It is a piece of industrial machinery that isn't confined to hydraulics or pneumatics. Adjusts the direction, flow, speed, and other properties of the medium in industrial control systems. The solenoid valve can work with a variety of circuits to provide the necessary control, and the control's accuracy and flexibility may be assured. A solenoid valve is a valve that is controlled by electricity. A solenoid is an electric coil with a moveable ferromagnetic core (plunger) at the middle of the valve. The plunger plugs a small hole in the rest position. A magnetic field is created by the current going through the coil. The plunger that opens the aperture is pushed upward by the magnetic field. To open and close solenoid valves, is the essential idea. Solenoid valves come in a variety of shapes and sizes. In different parts of the control system, different solenoid valves are used. Check valves, safety valves, directional control valves, speed control valves. and other types are the most widely utilized. Solenoid valves are primarily used to control the flow of liquids and gases through pipelines. FESTO from Germany, SMC from Japan, Airtac from Taiwan, and others are popular brands.
In principle, solenoid valves are divided into three categories: direct-acting, stepwise direct-acting, and pilot-operated.
Now I have made a summary from three aspects: introduction, principle, and characteristics.
Direct Acting Solenoid Valve
There are two types: normally closed and normally open. When the electricity is turned off, the normally closed type closes. The movable iron core overcomes the spring force and attracts the static iron core to directly open the valve when the coil is energized, and the medium is in a path; when the coil is de-energized, the electromagnetic force disappears and the moving iron core attracts the static iron core to directly open the valve, and the medium is in a path; when the coil is de-energized, the electromagnetic force disappears and the moving iron core attracts the static iron core to directly open the valve, and the Under the influence of spring force, the core is reset, the valve port is directly closed, and the medium is blocked. The structure is straightforward, the action is dependable, and it functions normally under zero pressure differential and micro-vacuum. Normally, the open type is the polar opposite of the closed type. Such as a solenoid valve with a flow diameter smaller than φ6.
Principle:
Type that is normally closed When the solenoid is charged, it generates electromagnetic force, which lifts the open portion off the valve seat and opens the valve; when the power is turned off, the electromagnetic energy vanishes, the spring forces the open part against the valve seat, and the valve closes. (Open type is the polar opposite of this.)
Features:
It can work normally under vacuum, negative pressure, and zero pressure, but the diameter generally does not exceed 25mm.
Step-by-step direct-acting solenoid valve
The first opening valve and the second opening valve are coupled in this type of valve. Step by step, the main valve and pilot valve are opened, allowing the electromagnetic force and pressure difference to open the main valve port directly. When the coil is powered, electromagnetic force is generated, causing the moving iron core and the static iron core to attract. The pilot valve port is opened and the pilot valve port is positioned on the main valve port, and the moving iron core and the main valve core are connected. The cavity's pressure is released through the pilot valve port, and the main valve core moves upward due to the pressure difference and electromagnetic force acting simultaneously, opening the main valve's medium flow. The electromagnetic force vanishes when the coil is de-energized. The moveable iron core seals the pilot valve hole under its own weight and spring force at this point. To boost the pressure in the top cavity, the medium enters the upper cavity of the main valve core through the balance hole. The medium is cut off when the main valve is closed due to spring return and pressure. Even when the pressure difference is zero, the structure is appropriate, the action is trustworthy, and the work is reliable. ZQDF, ZS, 2W, and so forth.
Principle:
It is a hybrid of direct action and pilot projects. The electromagnetic force raises the pilot tiny valve and the main valve closing member upwards in turn when there is no pressure difference between the inlet and the outlet, and the valve opens. After energization, the electromagnetic force pilots the small valve, the pressure in the lower chamber of the main valve rises, and the pressure in the upper chamber drops, causing the pressure difference to push the main valve upward; when the power is turned off, the pilot valve uses a spring to push the main valve upward. The closing piece is pushed downward by the force or medium pressure, closing the valve.
Features:
It can also be operated under zero pressure difference, vacuum, or high pressure, but the power is large, and it must be installed horizontally.
Indirect pilot solenoid valve
The pilot valve and main valve core are connected to produce a channel combination in this type of solenoid valve; the normally closed type is closed when it is not powered. The created magnetic force attracts the moving iron core and the static iron core when the coil is powered, the pilot valve port opens, and the medium flows to the outlet. At this point, the pressure in the upper chamber of the main valve core falls below that on the intake side, resulting in a pressure difference large enough to overcome the spring. To achieve the goal of opening the primary valve port and allowing the medium to flow, the resistance increases upwards. When the coil is de-energized, the magnetic force dissipates, and the spring force causes the movable iron core to reset and close the pilot port. The medium flows in through the balance hole at this point, the pressure in the upper cavity of the main valve core rises, and the main valve core travels downward due to the spring force. The primary valve port should be closed. The generally open principle is the polar opposite.
Principle:
When the electromagnetic force is activated, the pilot hole is opened, the pressure in the upper chamber rapidly lowers, and a large pressure difference forms around the open section. The open part of the valve is pushed upward by the fluid pressure, and the valve opens; when the power is turned off, the spring force opens the pilot hole, and the valve closes. The fluid pressure forces the opening member downward and opens the valve when the intake pressure travels through the bypass hole and the chamber soon produces a low and high-pressure difference around the valve closing member.
Features:
Small size, low power, high fluid pressure range upper limit, can be installed arbitrarily (need to be customized) but must meet the fluid pressure difference conditions.
The solenoid valve consists of two main components: the solenoid valve and the valve body (G). Figure 2 shows these components. There is a solenoid around the movable core located in the center, also called the plunger (E). It is an electric coil (A). It also consists of an armature (B), a light-shielding ring (C), a spring (D) and a seal (F). When stationary, it can be normally open (NO) or normally closed (NC). In the power-off state, the normally open valve is opened and the normally closed valve is closed. When current flows through the solenoid, the coil is energized and generates a magnetic field. This creates a magnetic attraction with the plunger, moving it and overcoming the force of the spring (D). If the valve is normally closed, the plunger will be lifted so that the seal (F) will open the orifice and allow the medium to flow through the valve. If the valve is normally open, the plunger moves down so that the seal (F) blocks the orifice and prevents the medium from flowing through the valve. The shading ring (C) prevents vibration and humming of the AC coil.
The solenoid valve's main function is to control the flow of liquid or gas in a forward, fully closed, or fully open mode. They're typically utilized to replace manual valves or to regulate them remotely. A solenoid valve's role is to open or close an aperture in the valve body, allowing or preventing flow through the valve. By activating the coil, the plunger raises or lowers the orifice within the sleeve, opening or closing the orifice.
The coil, plunger, and sleeve assembly make up the solenoid valve, The plunger return spring in a normally closed valve holds the plunger on the opening and prevents flow. When the solenoid coil is energized, the resulting magnetic field elevates the plunger, allowing flow to occur. When the normally open valve's solenoid is energized, the plunger seals the aperture, blocking the flow.
1. External leakage is blocked, internal leakage is easy to control, safe to use
Internal and exterior leakage is a factor that puts people's lives in danger. Other automatic control valves commonly extend the valve stem, with an electric, pneumatic, or hydraulic actuator controlling the rotation or movement of the valve core. Only the solenoid valve is completed by employing electromagnetic force to work on the iron core enclosed in the magnetic isolation sleeve, which must solve the problem of external leakage of the dynamic seal of the long-term valve stem. Because there is no dynamic seal, exterior leakage is simple to stop. The electric valve's torque control is difficult, and internal leakage is common, even if the valve stem's head is removed off; the solenoid valve's structure makes it simple to control internal leakage until it reaches zero. As a result, the solenoid valve is extremely safe to use, and it's especially well-suited to corrosive, toxic, or high- or low-temperature media.
2. The system is simple, it can be connected to an industrial computer, and the price is low
The solenoid valve is a low-cost device with a simple form. Other forms of actuators, such as control valves, are more difficult to install and maintain. What's more clear is that the composed automatic control system is a lot easier to use and costs a lot less. The solenoid valve is easy to link to an industrial computer because it is controlled by a switch signal. The benefits of solenoid valves are even more clear in today's period when computers are widely used and prices are falling rapidly.
3. Tiny movements, power, light appearance
The solenoid valve's response time can be as little as a few milliseconds, and the pilot solenoid valve can be operated in tens of milliseconds. It is more sensitive than other automatic control valves since it is a self-contained circuit. A well-constructed solenoid valve coil consumes extremely little power and is an energy-saving product; it can also maintain the valve position automatically by just triggering the action, and it consumes no electricity. The solenoid valve is compact, saving space while still being light and attractive.
4. The adjustment accuracy is limited, and the applicable medium is limited
In most cases, solenoid valves have only two states: on and off. Only two extreme positions are possible for the spool, and it cannot be modified constantly. (Many new ideas are attempting to break through, but they are still in the testing stage), therefore the accuracy of the adjustment is still limited. The cleanliness of the medium for solenoid valves is extremely important, therefore granular medium cannot be used. If it's contaminants, they must first be cleaned out. Furthermore, viscous media cannot be used, and the media's viscosity range for certain goods is quite limited.
5. Various models and wide-ranging applications
Solenoid valves have inherent flaws, but their benefits outweigh them, therefore they're built into a number of goods to fulfill a variety of purposes and have a wide range of applications. The progress of solenoid valve technology is also focused on overcoming innate flaws and making greater use of inherent advantages.
1. Select the voltage level and voltage fluctuation range of the solenoid valve coil based on the voltage of the electrical control circuit. Products with DC 24V coils are frequently utilized in general automation control systems. In addition, solenoid valve coils come in a variety of voltages, including DC12V, AC24V, AC110V, and AC220V.
2. Select various solenoid valves with several ports based on the mechanical action control strategy (pneumatic loads that need to be powered off and air-retained can be selected according to actual needs). The electromechanical valve). For example, the 4V210-08 series of Airteck two-position five-way single-control solenoid valves, where 4V stands for the product's specification code for two-position five-way or three-position five-way, and 2 stands for the 200 series' series code. In the actual selection, you can refer to the catalog of various products to find the type of solenoid valve we need. 10 means single electric control (20 means double electric control, 30C means middle seal type, 30E means middle vent type, 30P means medium pressure type), 08 means solenoid valve connector diameter (06: 1/8, 08 means 1/4), in the actual selection, you can refer to the catalog of various products to find the type of solenoid valve we need.
3. Choose the solenoid valve's air source pressure range and operating frequency per second based on the mechanical work requirements (usually between 0.15 and 0.8Mpa) (the highest operating frequency of commonly used solenoid valves is generally 3 to 5 times per second) in common usage The requirement can be met. Temperature, humidity, dust, vibration, and other environmental factors can be used.
4. If electric sparks could cause dust, gas, or other materials to explode, an explosion-proof solenoid valve should be chosen; otherwise, a safety accident could occur owing to the electric spark pulse generated during solenoid valve coil operation.
Reasonable solenoid valve design and selection may simplify the circuit and gas path, minimize the variety and number of solenoid valves, ensure the accuracy and reliability of the pneumatic system, reduce compressed air consumption, and make the equipment's appearance and maintenance easier. It also saves money.
1. When both coils of a dual-coil solenoid valve are energized at the same time, the solenoid valve's state is unexpected. As a result, it is impossible to precisely estimate the action of a weight such as a cylinder. It should be forbidden for the dual control coils to energize at the same time.
2. If the dual-control solenoid valve has a self-retaining function, turn it off to avoid overheating the coil and shortening its service life. After power on, the direction may usually be reversed and maintained in around 0.3 seconds.
3. If the solenoid valve is directly controlled by a PLC programmable controller, etc., and the output control type is transistor output, it is necessary to increase the intermediate relay control or parallel freewheeling diodes because the solenoid valve is an inductive load that will affect the life of the PLC output components. To reduce the effect of the reverse electromotive force generated when the transistor device's coil is turned off. Both AC and DC are possible with a relay-style output. It is advised that an intermediate relay be used for relay to avoid damage to the PLC contact due to an irregular solenoid valve coil.
4. Ordinary solenoid valves need to prevent rainwater from entering the solenoid valve coil.
(1) The solenoid valve coil terminal is loose or the wire terminal is loose, and the solenoid valve must not be energized. Check the solenoid valve coil circuit connection.
(2) The solenoid valve coil is burned out. Remove the wiring of the solenoid valve and measure with a multimeter. If it is open, the solenoid valve coil has burned out.
(3) When the solenoid valve is controlled by the coil, the manual reversing button of the solenoid valve is pressed, and the reversing reset is not possible. Check to see if the reversing button has been released.
(4) The solenoid valve is leaking, the solenoid valve's internal sealing gasket is damaged, or the sliding valve is worn, causing many cavities to blow-by, or the solenoid valve and sealing gasket are not locked in place when the valve plate is mounted, causing several cavities to blow-by. Examine the status of the sealing gasket lock. Alternatively, a new solenoid valve can be used.
Tip: Turn off the coil's voltage supply. When the air supply is normal, press the solenoid valve's manual valve opening button. If the solenoid valve is open, the valve is functioning normally. If the valve button is routinely switched back to the position after you release it, the solenoid valve pneumatic actuator is working well. If the solenoid valve coil is controlled by an external voltage and has a problem that prevents it from being operated, the circuit part can be troubleshot to reduce the scope of the fault examination.
Catalogue
FPGA / CPLD
Memory
MOS 
MCU 
DSP
OCEP
Secondary 
Other 