What are the main reasons for determining the quality factor of electric actuators?
Special motor, characterized by strong overload capability, large starting torque, small moment of inertia, short-term and intermittent operation.
A speed reduction mechanism for reducing the output speed of the motor.
A stroke control mechanism for adjusting and accurately controlling the opening and closing position of the electric actuator.
A torque limiting mechanism for adjusting the torque (or thrust) and not exceeding a predetermined value.
Manual, electric switching mechanism, interlocking mechanism for manual or electric operation.
The opening indicator is used to indicate the position during the opening and closing process.
The life of an electric actuator is the durability of an electric actuator. It is an important performance indicator for the finished electric actuator and has great practical economic significance. Usually expressed in terms of the number of opening and closing times that can guarantee the sealing requirements, it can also be expressed by the use time. The longer the use time of the electric actuator finished product proves that the electric actuator factory has a high level of electric actuator testing technology, and QTOT achieves this high quality. The electric actuator test standard, specializing in the production of advanced electric actuator test pressure testing equipment to improve the service life of electric actuator products. The connection type and size of the valve and the electric actuator should conform to the national standard: GB/T12222-1989 multi-turn valve drive connection, GB/T12223-1989 part of the rotary valve drive connection.
At present, some rotary valve electric actuators have mechanical limit to prevent the position of the valve disc from being judged. The correspondence between the screw holes and the keyway position between the valve and the electric actuator is strict.
The quality of the electric actuator is related to the output torque and speed of the equipment, the maximum number of revolutions of the stem nut, the allowable value of the stem diameter and the maximum thrust allowable value of the electric actuator.
The output torque value is one of the important technical parameters of the electric actuator, and it is also an important parameter to be selected in use. Excessive or insufficient output torque of the electric actuator selected when assembling the electric valve is not advisable. Because of the general situation, the electric actuator manufacturer needs to test and adjust the output torque value when the product leaves the factory, which is relatively accurate. If the excessive output torque margin is selected, the electric valve will have great potential danger. Once the control protection failure occurs, the valve will be easily damaged (the valve stem is bent and the valve body is broken), which is easy to cause. Pipeline system accident. Therefore, it is not advisable to select the output torque margin too large. If you can’t open the valve in actual work, it is unreasonable.
Regarding the determination of the output speed of the electric actuator, when the valve is not strictly required for its opening and closing time, the slower speed should be selected as much as possible.
Because of the unnecessary speed, the motor power will be increased under the same torque requirement, which not only wastes energy, increases engineering cost, but also causes the electric actuator to increase in volume and wastes many aspects.
At present, the electric actuators developed and developed in China have a small number of motor specifications designed in each frame number (generally 2-3 specifications), and the range ratio of the gear pair and the worm gear pair in the main drive is changed. Limited, so there is not much torque binning and speed binning for each frame number.
If the axial force of the valve is borne by the electric actuator (ie the stem nut is in the electric actuator), the thrust value must not exceed the permissible value of the electric actuator.
When using the multi-turn valve electric actuator, the maximum number of revolutions of the stem nut during valve operation must be stated, so that the relevant gear ratio of the position indication mechanism in the electric actuator can be correctly selected so that the position indication has sufficient accuracy to meet the valve. Observing the degree of opening and closing of the valve during the work process, otherwise it may cause illusion and affect normal work.
Lifting rod valve selection Electric actuator should pay attention to the diameter of the stem that is allowed to pass, the stem diameter must be less than this value. In addition, for multi-turn electric actuators, the height of the stem cover should be raised when selecting (related to the valve pain path). Rotary rod valves are not equipped with a stem cover.