As an actuator of automation instruments, solenoid valves have seen a sharp increase in usage in recent years. This article analyzes the main characteristics of solenoid valves and provides a brief overview of the development trends of mature technologies in China from an application perspective. It examines the directions of simplification, intelligence, generalization, and specialization, and briefly discusses the social factors that affect the development of solenoid valve technology.
1、 The main characteristics of solenoid valves
(1) The system is simple, easy to connect to a computer, and the price is affordable. The solenoid valve itself has a simple structure and low price, making it easier to install and maintain compared to other types of actuators such as regulating valves. More significantly, the composed self-control system is much simpler and priced much lower. Due to the fact that the solenoid valve is controlled by switch signals, it is very convenient to connect with industrial control computers. In today's era of widespread computer use and significant price reductions, the advantages of solenoid valves are even more apparent.
(2) External leakage is blocked, internal leakage is easy to control, and safe to use. Internal and external leakage is a factor that endangers safety. Other self-control valves usually extend the valve stem and control the rotation or movement of the valve core through electric, pneumatic, or hydraulic actuators. All of this needs to solve the problem of long-term leakage of valve stem seals; Only solenoid valves use electromagnetic force to seal the iron core inside the magnetic isolation sleeve, without dynamic sealing, so external leakage is easily blocked. Electric valve torque control is not easy, which can easily cause internal leakage and even break the valve stem head; The structural type of solenoid valve is easy to control internal leakage until it is reduced to zero. So, the use of solenoid valves is particularly safe, especially suitable for corrosive, toxic, or high and low temperature media.
(3) Action express, with minimal power and lightweight appearance. The response time of solenoid valves can be as short as a few milliseconds, and even pilot operated solenoid valves can be controlled within tens of milliseconds. Due to its self-contained circuit, it responds more sensitively than other self-control valves. A well-designed solenoid valve coil has low power consumption and is considered an energy-saving product; It can also automatically maintain the valve position by triggering the action, without consuming any electricity during normal operation. The electromagnetic valve has a small external size, which saves space and is lightweight and beautiful.
(4) Diverse models and versatile applications. Although solenoid valves have inherent shortcomings, their advantages are still very prominent, so they are designed into a variety of products to meet different needs and have a wide range of applications. The progress of solenoid valve technology also revolves around how to overcome inherent shortcomings and better leverage inherent advantages.
(5) The adjustment accuracy is limited and the applicable medium is restricted. Electromagnetic valves usually have only two states: on/off, and the valve core can only be in two extreme positions, which cannot be continuously adjusted. (There are many new ideas trying to break through, but they are still in the experimental stage) Therefore, the adjustment accuracy is still limited to a certain extent. Electromagnetic valves have high requirements for the cleanliness of the medium, and are not suitable for media containing particles. If impurities are present, they must be filtered out first. In addition, viscous media are not suitable, and the viscosity range of media suitable for specific products is relatively narrow.
2、 Introduction to the Development of Electromagnetic Valve Technology More Electromagnetic Valve Technology
The development of the direction of refinement and simplification is essential, and only simplicity can be passed down for a long time. This is also the eternal pursuit of scientists and engineers.
(1) Simplify the control circuit. Previous actuators extensively used pneumatic and electric control circuits, which increased the complexity of the system. Pilot operated solenoid valves, on the other hand, form a control circuit inside the valve that utilizes the working medium itself, with a very simple structure. In the past, multiple technical parameters of solenoid valves at home and abroad were still limited, but now the diameter of solenoid valves in China has been expanded to 300000 mm; The medium temperature ranges from -200 ℃ to 450 ℃; The working pressure ranges from vacuum to 25MPa. The action time ranges from tens of seconds to a few milliseconds. The new development of these technologies can completely replace the bulky and expensive two position control quick shut-off valves, pneumatic switch valves, electric switch valves, and partially replace continuous adjustment pneumatic and electric control valves. (How to better meet the requirements of adjustment accuracy, which will be discussed in the following text). Foreign industries such as textiles, light industry, and urban construction have extensively adopted solenoid valves, while metallurgical and chemical industries have taken the lead in using more and more solenoid valves in auxiliary systems.
Domestic automation professionals are increasingly paying attention to solenoid valves.
(2) When simplifying the operation of the automatic control valve in the pipeline system, some auxiliary valves and fittings must also be equipped on the pipeline. This piping system takes up a large amount of space, is time-consuming to install, and is prone to leakage. The ZDF series multifunctional solenoid valve cleverly eliminates these additional accessories and still has the function of isolating bypass, thus winning the Geneva International New Technology Gold Award. A filter needs to be installed in front of the automatic control valve. When multiple self-control valves are used in combination, it is often necessary to install one-way valves to prevent interference between pipelines. Now, one-way solenoid valves, combination solenoid valves, and filtered solenoid valves have all played a role in simplifying pipelines.
