The hottest new development of magnetic valve tech

New development of magnetic valve technology in China

as an actuator of automatic instruments, the consumption of magnetic valve has increased sharply in recent years. This paper analyzes the main characteristics of solenoid valve, and briefly summarizes the development trends of domestic mature technology from the perspective of application, investigates the directions of simplification, intelligence, generalization and specialization, and briefly discusses the social factors affecting the development of solenoid valve technology

I. main features of solenoid valve

(1) the external leakage is blocked, the internal leakage is easy to control, and the use is safe. Internal and external leakage is a factor endangering safety. Other automatic control valves usually extend the valve stem, and the rotation or movement of the valve core is controlled by electric, pneumatic and hydraulic actuators. It is necessary to solve the problem of leakage of long-term action valve stem dynamic seal; Only the solenoid valve is completed by using electromagnetic force on the iron core sealed in the magnetic isolation sleeve. There is no dynamic seal, so the external leakage is easy to be blocked. Electric valve torque control is not easy, easy to produce internal leakage, and even pull off the valve stem head; The structure of the solenoid valve is easy to control internal leakage until it is reduced to zero. Therefore, the solenoid valve is particularly safe to use, especially for corrosive, toxic or high and low temperature media

(2) the system is simple, easy to connect to the computer, and the price is low. The solenoid valve itself has simple structure and low price, which is easier to install and maintain than other types of actuators such as regulating valve. What is more remarkable is that the automatic control system is much simpler and the price is much lower. Because the solenoid valve is controlled by switching signal, it is very convenient to connect with industrial computer. In today's era when computers are popular and prices have fallen sharply, the advantages of solenoid valves are more obvious

(3) the action is express, with small power and light shape. The response time of the solenoid valve can be as short as a few milliseconds, and even the pilot solenoid valve can be controlled within tens of milliseconds. Because of its own circuit, it is more sensitive than other automatic control valves. The properly designed solenoid valve coil has low power consumption and is an energy-saving product; It can also automatically maintain the valve position by triggering the action, and it does not consume electricity at all at ordinary times. The size of the solenoid valve is small, which saves space and is light and beautiful

(4) the adjustment accuracy is limited, and the applicable medium is limited. The solenoid valve usually has only two states of opening and closing, and the valve core can only be in two limit positions and cannot be adjusted continuously. (there are many new ideas trying to break through, but they are still in the trial stage). Therefore, the adjustment accuracy is still limited

the solenoid valve has high requirements on the cleanliness of the medium, and the medium containing particles cannot be applied. If it is an impurity, it must be filtered first. In addition, viscous media cannot be applied, and the viscosity range of media applicable to specific products is relatively narrow

(5) solenoid valves have various models and wide applications. Although the solenoid valve has inherent shortcomings, its advantages are still very prominent, so it is designed into a variety of solenoid valve products to meet different needs and have a wide range of uses. The progress of solenoid valve technology also revolves around how to overcome (1) adopt sticky soft rubber on the surface in contact with the sample; To overcome the inherent shortcomings, how to give better play to the inherent advantages

II. Introduction to the development of solenoid valve technology more solenoid valve technology

2.1. The development in the direction of refinement and simplification must be as simple as possible, and only simple ones can be spread for a long time. This is also the permanent pursuit of scientists and engineers

(1) simplify the control circuit. In the past, a large number of actuators used pneumatic and electric control circuits, which increased the complexity of the system, while the pilot solenoid valve formed a control circuit using the working medium itself in the valve, with a very simple structure. In the past, many technical parameters of solenoid valves at home and abroad were also limited, and now the diameter of domestic solenoid valves has been expanded to 30ommm; The medium temperature is as low as --200 ℃ and as high as 450 ℃; The working pressure is from vacuum to 25MPa. The action time ranges from more than ten seconds to a few milliseconds. The new development of these technologies can completely replace the original bulky and expensive two position control fast shut-off valve and pneumatic on-off valve, electric on-off valve, and can also partially replace the pneumatic and electric control valves with continuous regulation. (how to better meet the requirements of adjustment accuracy is also discussed below). Foreign textile, light industry, urban construction and other industries have largely changed to solenoid valves, while metallurgy, chemical industry and other industries are the first to use more and more solenoid valves in auxiliary systems

domestic automatic control professionals have paid more and more attention to solenoid valves

(2) simplify the pipeline system. When the automatic control valve works, some auxiliary valves and pipe fittings must be equipped on the pipeline. For example, the isolation bypass shown in Figure 1 is a typical installation method, which must be equipped with three manual valves, of which manual valve 1 is a bypass valve, which is manually standby. Manual valves 2 and 3 are isolation valves to ensure the maintenance of automatic control valve 5. Of course, it must be equipped with two tees 4 and unions 6. This kind of pipeline system takes up a large space, takes a long time to install, and is easy to leak. ZDF series multi-function solenoid valve cleverly omits these additional accessories and still has the function of isolating bypass, so it won the gold medal of Geneva International new technology. A filter shall be installed in front of the automatic control valve. When multiple automatic control valves are used together, check valves are often installed to prevent interference between pipelines. Now, the one-way solenoid valve, combined solenoid valve and solenoid valve with filter have all played a role in simplifying the pipeline

(3) simplified valve structure and process solenoid valve are automatic control valves with simple principle and structure, but they need to be further simplified. The structure and technology of the components of the solenoid valves for washing machines and refrigerators in the household appliance industry are suitable for mass production. The coil components of ordinary solenoid valves have been encapsulated in plastic to reduce the failure of broken outgoing lines, and it is easy to meet the protection requirements of waterproof and explosion-proof. The valve body, bonnet and other components have adopted precision casting, forging and other processes, and engineering plastic magnetic valves have also been listed in batches. Domestic explosion-proof electric long glass fiber reinforced technology, that is, the incorporation of glass fiber magnetic valves into plastics, is not only explosion-proof, but also has cast-in-place and intrinsically safe types. High pressure and high temperature solenoid valves have also appeared, simplifying the structure and process

2.2. The development in the direction of intellectualization mainly refers to how to better cooperate the solenoid valve with the intelligent instrument to improve the control accuracy and reliability of the system. It is generally believed that the position adjustment is difficult to achieve high accuracy, but in many cases, the required high accuracy can be achieved by adopting appropriate methods, which greatly saves the cost. More solenoid valves. Detection of spring tightening under specific pressure: press the pressing plate down to the set pressure and stop the technology

(1) double combined solenoid valve. This is a combination of solenoid valves of different sizes. The oil metering accuracy of the widely used fuel dispensers is as high as 0.02%, and the double solenoid valve is adopted. The large valve is opened, so that the refueling is nearly completed in a short time; Then the large valve is closed, and the small valve is added to ensure the flow accuracy. This technology has been used abroad for many years, and the products are manufactured by ascohoneywell, a world-famous professional solenoid valve company. The dual solenoid valve has reached the index of imported products and has unique performance. By the way, it is pointed out that the measurement of large flow in domestic oil depots is also introducing or imitating foreign multi-stage shut-off valves with complex structure and unstable performance. This product is not made by world-famous professional companies, because the market demand is not enough to attract their interest. In fact, our oil depot will use domestic double combination valves with large flow, which will have a much better effect. Double combination valve is also often used to control temperature, pressure, liquid level and other parameters. The large valve guarantees the basic quantity, and the small valve provides the compensation quantity. In the system with relatively stable parameters, this position control can achieve quite high accuracy. For many systems with large parameter changes, the rate of change is still subject to certain constraints, such as the temperature control system, which is still affected by thermal inertia. Therefore, the properly used double combination valve can greatly reduce the cost compared with the control valve on the premise of meeting the control requirements

(2) the spool of three position solenoid valve and digital valve has three working positions, which are usually not powered on and in a slightly open state, and the valve provides initial flow; For an electrical signal, the solenoid valve is fully opened to provide large flow; Give another electrical signal and close the valve

the valve is also equipped with a manual device, so that there is no need to consume electricity when closing the valve for a long time. The three position solenoid valve can be regarded as a double solenoid valve with a more compact structure. It can easily realize three position regulation and has been widely used. The further idea of ZDF multi-function solenoid valve is that n solenoid valves with a certain proportion of size form 2n kinds of flow, which is similar to digital circuit, and this kind of combined valve is called digital valve. In fact, two double valves or three position valves with different sizes can produce 24=16 or 32=9 kinds of flow, which has achieved very high accuracy. In principle, it has advantages in matching with industrial computer, but because there is no large demand in the application field, this technology is still in the experimental stage

(3) self holding solenoid valve self holding solenoid valve is to complete the valve opening and closing action only by momentary energization, and the valve core position does not need electricity to maintain. Its advantage is to save energy, especially when batteries are used as power supply, and temperature rise can not be considered, so the coil has long service life and high safety in high and low temperature, explosion-proof and other occasions. The common ones are mechanical holding and permanent magnet holding, which are divided into double coil and single coil. The single coil magnetic holding structure is the simplest. It changes the polarity of the DC power supply to change the two states of the corresponding valve switch. This kind of solenoid valve has its own coil, and the external wiring needs to add a change-over switch, which is very convenient to match with the intelligent instrument. The solenoid valve equipped with IC card pre charge gas meter and water meter is one of the keys to the success or failure of the instrument, and the self-sustaining technology is an important factor for the success or failure of the solenoid valve. The domestic self-sustaining solenoid has become increasingly mature, and the company has provided supporting facilities for many smart meter factories

2.3. Development in the direction of generalization. Solenoid valves are widely used, but the use conditions are very different. Enhancing the general performance and reducing the cost of manufacturing, purchase and sale, storage, installation and maintenance have taken a big step in this regard in recent years

(1) the response time can be adjusted. The time from giving the electric signal to the completion of the valve core action is called the response time. Different occasions want different switching speeds, and there are four combinations: fast on and fast off ---- for fast response system; Fast opening and slow closing ---- used to prevent water hammer; Slow on and fast off --- used for slow start and emergency stop; Slow opening and slow closing - used for smooth transition. ZDF multi-function solenoid valve can be adjusted in any state, and its application is very flexible

(2) expansion media is applicable. The difference between solenoid valve and other automatic control valves is that the applicable range of medium viscosity is narrow, so the structural parameters of pilot solenoid valve are different from those of air, water, steam, oil and other media; Generally speaking, it is not universal. The ZDF multi-function solenoid valve only uses a small screw, but it achieves the versatility of gas, water and oil, and also greatly widens the application range of oil viscosity, which is very popular

(3) when using the solenoid valve with adjustable opening and in action and kiln, it is often hoped that it has manual function as a backup in case of power failure or failure. For more solenoid valve technology, generally, the manual device can only open or close the valve manually, and the one with both is called fully manual. The manual device can also preset the valve opening. Generally, manual can only preset the maximum or minimum opening of the valve, while full manual can preset the maximum or minimum opening respectively. ZDF multi-function solenoid valve is fully manual. Other types of solenoid valves can be equipped with simple general manual valves as required