· Why are electric actuators becoming more and more popular?
· How did electric actuators develop?
· What are the categories of electric actuators?
· Working principle of electric actuator?
· What parts does an intelligent electric actuator consist of?
Why are electric actuators becoming more and more popular?
In the era of automation and high speed, there are many reasons why electric actuators are popular in many industries.
Diverse product types
Electric actuators are very rich in product types, including three major categories: quarter-turn, multi-turn, and linear-turn. Each category contains corresponding different models. According to the different models, there are on-off type, modulating type, intelligent type, explosion-proof type, etc.
Wide application areas.
In the future, through product updates to improve efficiency and expand the scope of application, electric actuators have a very wide range of applications, that is, they run through multiple industries, so the utilization rate in the application field is extremely high and powerful. The application areas of high-quality electric actuators include the use of oil and gas pipelines and platforms, nuclear heating and power generation in the power industry, and general use also includes food and air conditioning.
Electric actuators with high product performance occupy an extremely important position in the modern market, which is also due to their strong product performance. Intelligently control the rotation angle, control the speed and efficiency of the pipeline flow, and manage the position of the valve in the pipeline well. The product performance can be tested in many places. Reliable electric actuators can achieve multi-industry compatibility. With the continuous development of technology and the upgrading of products, electric actuators will have greater potential, enabling faster updates and improvements in product performance, further reducing the workload of technicians and improving work efficiency. Industry insiders are positive about the future development of electric actuators and hope to make greater contributions in more fields.
How did electric actuators develop?
With the rapid development of microelectronics, computers, communication network technology and mechatronics technology, intelligent electric actuators have appeared internationally since the 1990s. It is a new type of intelligent terminal actuator with a microprocessor. Since then, intelligence has formed the general trend of actuator development, and it is very necessary to understand the development status of intelligent electric actuators as soon as possible.
The automatic modulating system of industrial production process is composed of detectors, regulators, actuators and modulating objects. Among them, the actuator is always indispensable, generally composed of an actuator and a regulating mechanism (generally called a control valve). In addition, accessories such as valve positioners and handwheel mechanisms can be equipped as needed.
Actuators play a very important role in the automation of modern production processes and are often called the "hands and feet" to realize the automation of production processes. Electric actuators use electrical energy as power, accept standard signals (analog or digital) from regulators, and automatically change the operating variables (control valves, dampers etc.) by converting this signal into corresponding mechanical displacements (angles, straight lines or multiple turns) to achieve the purpose of automatically adjusting the adjusted parameters (temperature, pressure, flow, liquid level, etc.) so that the production process can be carried out according to predetermined requirements. Therefore, electric actuators have a great impact on the operation, reliability and quality of the automatic control system.
Compared with pneumatic and wave actuators, electric actuators have three main advantages:
(1) No special air source and air purification devices are required. Even if the power is off, the original execution position can be maintained;
(2) Signals can be transmitted over long distances, and cable laying is much more convenient than laying gas pipes and liquid pipelines, and it is easy to check the line;
(3) It is convenient and simple to connect to the computer, and is more suitable for the use of new electronic information technologies.
What are the categories of electric actuators?
Electric actuators are classified according to valve types:
1. Quarter-turn electric actuator; the rotation of the output shaft of the electric actuator is less than one circle, usually 90 degrees to achieve the opening and closing process control of the valve. This type of electric actuator is divided into two types according to the different installation interface methods: direct mounted type and foot-plate mounted type.
a) Direct mounted type: refers to the form in which the output shaft of the electric actuator is directly connected to the valve stem.
b) Foot-plate mounted type: refers to the form in which the output shaft is connected to the valve stem through a crank. This type of electric actuator is suitable for butterfly valves, ball valves, plug valves, etc.
2. Multi-turn electric actuator (rotation angle > 360 degrees); this type of electric actuator is suitable for gate valves, globe valves, diaphragm valves, etc.
3. Linear-turn electric actuator (linear motion); this type of electric actuator is suitable for single-seat control valves, double-seat control valves, etc.
According to the function of the valve, it is divided into two categories: switch type and regulating type:
1. On-off type - On-off type electric actuators generally realize the opening or closing control of the valve. The valve is either in the fully open position or in the fully closed position. This type of valve does not require precise control of the medium flow. It is particularly worth mentioning that switch type electric actuators can also be divided into split structure and integrated structure due to different structural forms.
-a) Split type (usually called ordinary type): The control unit is separated from the electric actuator. The electric actuator cannot control the valve alone. An external control unit must be added to achieve control. Generally, the external controller or control cabinet is used for matching. The disadvantage of this structure is that it is not convenient for the overall installation of the system, increases the wiring and installation costs, and is prone to failure. When a failure occurs, it is not convenient for diagnosis and maintenance.
-b) Integrated type (usually called integral type): The control unit and the electric actuator are packaged into one, and can be operated on the spot without an external control unit. Remote operation can be performed by simply outputting relevant control information. The advantages of this structure are that it is convenient for the overall installation of the system, reduces wiring and installation costs, and is easy to diagnose and troubleshoot.
2. Modulating type - The modulating type electric actuator not only has a on-off type integrated structure to accurately adjust the medium flow. It can also accurately control the valve.
-a) Control signal type (current, voltage); The control signal of the modulating type valve electric actuator generally has a current signal (4~20mA, 0~10mA) or a voltage signal (0~5V, 1~5V).
Working principle of electric actuator?
The electric actuator is a device in the automation technology tool that receives control information and exerts control on the controlled object. The actuator is also an instrument that directly changes the manipulated variable in the forward path of the control system, and is composed of an actuator and a regulating mechanism.
Working principle of electric actuator: At the gear stage, the engine speed can be transmitted to the output rod through two sets of gears. The main reducer is completed by planetary gears, and the auxiliary reducer is realized by a worm gear, which is fixed in the center position by a set of tightened springs. In the event of overload, that is, when the output rod exceeds the set torque of the spring, the worm gear will undergo axial displacement, and the switch and signal device will be fine-tuned, and the electric actuator provides protection for the system.
Affected by the coupling operated by the external variable control lever, the output rod is coupled with the worm gear when the engine is working, and is coupled with the handwheel when manually operated. When the engine is not working, the electric actuator can easily disconnect the motor drive and connect the handwheel by simply pressing the control lever. Since the motor drive takes precedence over manual operation, the reverse action will automatically occur when the engine is started again. This can avoid turning on the handwheel when the engine is running, which is beneficial to protecting the system.
Since the handwheel is directly coupled to the output rod, normal manual operation of the electric actuator can be guaranteed when the internal gear fails or is damaged.
What parts does an intelligent electric actuator consist of?
1. Shell: The shell is made of hard aluminum alloy, anodized and polyester powder coated, with strong corrosion resistance, the protection level is IP67, and IP68 and explosion-proof types are available.
2. Motor: Fully enclosed squirrel-cage motor, small size, large torque, low inertia force, insulation class F, built-in overheat protection switch, which can prevent overheating and damage to the motor.
3. Manual structure: The design of the handwheel ensures reliability, labor saving and small size. When the power is not turned on, the clutch handle can be manually operated. When the power is turned on, the clutch automatically resets.
4. Indicator: The indicator is installed on the central axis, and the position of the valve can be observed. The mirror surface is designed with a convex lens, which does not accumulate water and is more convenient to observe.
5. Dryer: used to control the temperature, prevent moisture condensation inside the actuator due to temperature and weather changes, and keep the internal electrical components dry.
6. Limit switch: mechanical and electronic double limit. The mechanical limit screw is adjustable, the electronic limit switch is controlled by the cam mechanism, and the simple adjustment mechanism can accurately and conveniently set the position without battery support.
7. Torque switch: It can provide overload protection. When the valve is stuck and there is foreign matter, it will automatically disconnect the motor power supply, which can more effectively protect the valve from damage.
8. Self-locking: Precise double worm gear mechanism can efficiently transmit large torque, high efficiency, low noise, long life, self-locking function, prevent reverse rotation, stable and reliable transmission part, has been filled with high-efficiency grease at the factory, no need to use it again. come on.
9. Anti-dropping bolts: When the shell is removed, the bolts are attached to the shell and will not fall off. The external bolts are made of stainless steel.
10. Digital display of valve position: During the opening or closing process of the electric actuator, the change of valve position is displayed in real time in large numbers on the LCD screen.
