Solenoid valve is a solenoid-controlled industrial equipment, in the refrigeration system to adjust the direction of the media, flow, speed and other parameters. For the characteristics of the solenoid valve, solenoid valve should be how to choose? In order to extend the life of the solenoid valve, but also how to maintain it?
Interpretation | Solenoid valve structure principle know?
(1. Body 2. Air Inlet 3. Air Outlet 4. Wire 5. Plunger)
After reading the dynamic diagram, is not found that the working principle of the solenoid valve is very simple too! When the solenoid valve is not energized, the valve pin will bet the channel of the valve body under the action of the spring, and the solenoid valve will be in the off state. When the coil is connected to the power supply, the coil generates a magnetic force, and the valve core is lifted upward against the spring force, the valve passage is opened, and the solenoid valve is in an on state.
Simple point, the solenoid valve is divided into three categories
Solenoid valve principle is divided into three categories: direct-acting, step-by-step, pilot-type.
Small seven from the introduction, principles, characteristics of a summary made in three aspects:
Direct-acting solenoid valve
Introduction:
There are two types of normally closed and normally open. Normally closed when the power is turned off, when the coil is energized to produce electromagnetic force, so that the moving core overcomes the spring force with the static iron core pull directly open the valve, the medium was access; electromagnetic force disappeared when the coil power off, moving iron Under the action of the spring force, the core is reset and the valve port is closed directly. The medium can not be connected. Simple structure, reliable action, zero pressure and micro-vacuum work properly. Normally open type is the opposite. Such as less than φ6 flow path solenoid valve.
principle
Normally closed type power, the electromagnetic coil electromagnetic force to open parts from the valve seat lift, the valve opens; power failure, the electromagnetic force disappears, the spring pressure to open the valve seat, the valve open. (Normally open type on the contrary)
Features
In the vacuum, negative pressure, zero pressure can work properly, but the path is generally not more than 25mm.
Step by step direct-acting solenoid valve
Introduction
This valve uses a valve and the second open valve connected in one, the main valve and pilot step by step so that the electromagnetic force and pressure directly open the main valve port. When the coil is energized, the electromagnetic force is generated so that the moving iron core and the static iron core are closed, the pilot valve port is opened and the pilot valve port is arranged on the main valve port, and the moving iron core is connected with the main valve spool. At this time, Cavity pressure unloading through the pilot valve port, the pressure difference and the electromagnetic force at the same time under the action of the main spool upward movement, open the main valve medium circulation. When the coil power is lost when the electromagnetic force disappears, then move the core in the weight and spring force under the action of closing the pilot valve hole, then the medium in the balance hole into the main spool on the cavity, so that the pressure on the cavity, this time The main valve is closed by spring return and pressure and the medium is shut off. Reasonable structure, reliable action, work at zero pressure difference is also reliable. Such as: ZQDF, ZS, 2W and so on.
principle
It is a direct acting and pilot-based combination of principles, when there is no pressure difference between the inlet and outlet, the electricity, the electromagnetic force directly to the pilot valve and the main valve closing member in turn lift up, the valve opens. When the inlet and outlet to achieve the start of the pressure difference, the electricity, the solenoid pilot small valve, the main valve lower chamber pressure rises, the pressure on the chamber down, so that the use of pressure to push the main valve up; power off, the pilot valve spring Force or media pressure to push the closure, move down, the valve closed.
Features
In zero pressure or vacuum, high pressure can also be action, but the power is larger, requiring horizontal installation.
Indirect pilot solenoid valve
Introduction
This solenoid valve by the pilot valve and the main valve connected to form a combination of channels; normally closed in the absence of electricity, was closed. When the coil is energized, the magnetic force generated so that the moving core and the static iron core pull, open the pilot valve port, medium flow to the outlet, then the pressure on the main spool to reduce the pressure on the inlet side of the formation of pressure to overcome the spring Resistance and then move up to achieve the purpose of opening the main valve port, medium circulation. When the coil is de-energized, the magnetic force disappears. The movable iron core is reset to close the pilot port under the action of the spring force. At this time, the medium flows in from the balance hole, the pressure in the upper cavity of the main valve increases and moves downward under the spring force, Close the main valve port. The principle of normally open is the opposite.
principle
When the power is on, the electromagnetic force opens the pilot hole and the pressure in the upper chamber drops rapidly, forming a high pressure drop across the open part. The fluid pressure pushes the open part to move upward and the valve opens. When the power is off, the spring force opens the pilot port , The inlet pressure through the bypass hole quickly chamber in the valve around the formation of the next high pressure drop, the fluid pressure to promote the open piece to move down to open the valve.
Features
Small size, low power, high fluid pressure range high, can be installed (to be customized), but must meet the fluid pressure conditions.
Information | Analysis of the characteristics of the solenoid valve
1 leakage blocked, internal leakage easily controlled, safe to use
Internal and external leaks are elements that endanger safety. Other self-control valve stem usually stick out by the electric, pneumatic, hydraulic actuator control spool rotation or movement. This must solve the long-term action of the valve stem seal leakage problems; only the electromagnetic valve is the role of electromagnetic force sealed in the magnetic separation within the sleeve to complete the core, there is no dynamic seal, so easy to block leakage. Electric valve torque control is not easy, prone to internal leakage, and even pulled off the stem head; structure of the solenoid valve easy to control the internal leakage until it drops to zero. Therefore, the use of special safety solenoid valve, especially for corrosive, toxic or high temperature medium.
2 system is simple, then connect the computer, the price is low
Solenoid valve itself is simple, the price is low, compared to other types of actuators such as regulating valve easy to install and maintain. Even more remarkable is the composition of the control system is much simpler, the price is much lower. As the solenoid valve is the switch signal control, and industrial computer connection is very convenient. In today's popularization of computers, the price plummeted era, the advantages of the solenoid valve even more pronounced.
3 action, power is small, lightweight appearance
Solenoid valve response time can be as short as a few milliseconds, even the pilot solenoid valve can be controlled within a few tens of milliseconds. Since the self loop, more responsive than other self-controlled valves. Well-designed solenoid valve coil power consumption is very low, is an energy-saving products; can also be done only trigger action, automatically maintain the valve position, usually do not consume electricity. Solenoid valve small size, saving space, but also lightweight and beautiful.
4 adjustment accuracy is limited, the applicable medium is limited
Solenoid valve usually only switch two states, the spool can only be in two extreme positions, can not be adjusted continuously (trying to break a lot of new ideas, but are still in the trial stage of the trial) so the regulation accuracy is subject to certain restrictions. Solenoid valve on the media have high cleanliness requirements, including granular media can not be applied, in the case of impurities must be filtered out. In addition, viscous media can not be applied, and the range of media viscosities for a particular product is relatively narrow.
5 models are diverse and versatile
Although solenoid valve inherent deficiencies, the advantages are still very prominent, so it is designed into a wide range of products to meet a variety of different needs, the use of a very wide range. Solenoid valve technology is also progress around how to overcome the inherent deficiencies, how to better play its inherent advantages and expand.
Hot | Solenoid valve selection
1, economy
There are many solenoid valves can be universal, in the choice of the process should choose the most economical product.
2, safety
The general solenoid valve is not waterproof, please do not allow the waterproof conditions, the factory can be customized. The highest nominal pressure solenoid valve nominal pressure must exceed the maximum pressure within the pipeline, otherwise the service life will be shortened or other unexpected situations.
A corrosive liquid should be used in all stainless steel, corrosive fluids should use the plastic king (SLF) solenoid valve. Explosive environment must choose the appropriate explosion-proof products.
3, reliability
Solenoid valve is divided into two types of normally closed and normally open; generally use normally closed type, power open, power off; but a very long time to open a very short time to use the normally open type.
Life test, the factory generally belongs to the type test project, to be exact, our country does not have the professional standard of the solenoid valve, so carefully choose the solenoid valve manufacturer. Action time is very short When the frequency is high, choose direct acting large-caliber quick selection.
4, applicability
The fluid in the pipeline must be consistent with the medium calibrated in the selected solenoid valve series models. Fluid temperature must be less than the selected solenoid valve calibration temperature. Solenoid valve to allow liquid viscosity generally below 20CST, greater than 20CST should be noted.
Working pressure, the highest pipeline pressure is less than 0.04MPa should be used, such as ZS, 2W, ZQDF, ZCM series, such as direct acting and stepper direct acting. Minimum working pressure greater than 0.04MPa can choose pilot (differential pressure) solenoid valve, the maximum working pressure should be less than the maximum solenoid valve calibration pressure.
General solenoid valve are one-way work, so pay attention to whether there is anti-pressure difference, if installed check valve.
The fluid cleanliness is not high should be installed in front of the solenoid valve filter, the general requirements of the solenoid valve cleanliness is better. Pay attention to the flow aperture and take over the caliber, the solenoid valve is generally only two switches control; conditions permit installation of the bypass pipe, easy maintenance; water hammer phenomenon to be customized when the solenoid valve opening and closing time adjustment.
Note that the ambient temperature on the solenoid valve power supply current and power consumption should be selected according to the output capacity, the power supply voltage is generally allowed ± 10%, we must pay attention to AC starting VA value is higher.
Note | Solenoid valve maintenance
Matters needing attention
Pilot solenoid valve, to check whether the pressure difference within the pipeline is too small, the pressure is too small solenoid valve can not work, in this case, you need to use direct-acting solenoid valve. The pressure is too large, far beyond the design value of the solenoid valve can not work, it should be used high-pressure solenoid valve.
Matters needing attention II
Solenoid valves are generally installed horizontally, if the pepper side of the installed, it may cause the valve closed lax, that is, due to leakage, as far as possible to avoid the side equipment.
Matters needing attention three
Use a longer time, such as the piston and the seat between the seal is not good, the piston seal surface can be re-polished, and then seat grinding.
Matters needing attention four
Work, pay attention to the valve before and after the pressure gauge, the working pressure must not exceed the rated pressure, working pressure must be within the rated pressure range. When the working pressure exceeds the rated pressure or working pressure exceeds the rated pressure difference, the solenoid valve to stop using, close before and after the manual valve to prevent the solenoid valve explosion and leakage.
Note five
Solenoid valve installation, access to the media must be tested several times to confirm the normal before they can be put into formal use.
Note six
Should be regularly cleaned inside and outside the valve and the armature pull the dirt surface. Be careful not to damage the sealing surface.
Note seven
Solenoid valve longer time not to be closed before the valve manual valve, re-enable, the steam solenoid valve should be excluded from the condensate clean, and try to move several times until the normal switch before re-put into use.
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