Integration of the overall structure.
The intelligent process of electric valves is inseparable from the integrated design of valve and electric actuator. The overall structure is adopted, and the entire control loop of the valve is installed on a field instrument, which greatly simplifies the design, installation, operation and maintenance of the control system, and also reduces system failures caused by leakage and interference during signal transmission. , Improve the reliability of the system.
The valve position has only three positions: switch position and intermediate position. The valve position is controlled by the output torque of the valve motor. In China, the general solenoid valve wiring uses a stroke switch to control the valve motor, and a torque switch plays a protective role. However, travel switches and torque switches are usually installed on electric actuators, so the valve position signal cannot be directly obtained from the valve shaft, which makes the valve position indication value only a large value, which leads to the valve being closed or improperly opened.
If the output torque of the controlled valve is selected too small, it is easy to cause the solenoid valve of the car to be electrically driven and burned; if the output torque is selected too large, once the control of the electric actuator fails, it is easy to cause partial structural damage of the valve. This control method cannot directly control the opening and closing and adjustment of the valve, and the control accuracy is low.
On the other hand, in this working mode, the long-term action of the straight-stroke stop valve and the gate presses the inner wall of the pipeline to form a micro-groove, which will cause the valve to close poorly and cause leakage. Leakage is one of the sources of industrial pollution. The leakage of valves will increase consumption, cause medium loss, and reduce the economic benefits of enterprises. If the leaked medium is flammable, explosive, toxic, and harmful, it is prone to fire, explosion, poisoning, and personal injury accidents. The leakage of strong corrosive medium will accelerate the corrosion of plant and equipment and shorten its service life.