Operating torque The operating torque is the most important parameter for purchasing the valve electric device. The output torque of the electric device should be 1.2 to 1.5 times the maximum working torque of the valve electric device.
The main engine structure has two electric devices for operating the thrust valve:
One is that the thrust plate is not equipped, and the torque is directly output;
The second is to configure the thrust plate to convert the output torque from the stem nut on the thrust plate into output thrust.
The number of rotations of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem, the number of thread heads, etc., calculated according to M=H/ZS (M is the total number of rotations that the electric device should meet, and H is the valve Opening height, S is the number of valve drive thread heads, Z is the number of valve drive thread heads).
For the stem diameter of the multi-turn type rising stem valve, if the maximum stem diameter allowed by the electric device cannot pass through the stem of the equipped valve, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the rising stem valve. For the air-conditioning solenoid valve part-turn valve and the dark-stem valve of the multi-turn valve, although there is no need to consider the diameter of the valve stem, the diameter of the valve stem and the size of the keyway should be fully considered when selecting, so that it can be normal after assembly jobs.
If the opening and closing speed of the output speed regulating valve is too fast, water hammer is likely to occur. The appropriate opening and closing speed should be selected according to different conditions of use. The electric actuator of this kind of valve has a special requirement, that is, it must be able to limit the torque or axial force. The electric actuator of the valve generally uses a torque limiting coupling. After the technical indicators of the electric drive device are determined, its control torque is also determined. Usually it runs within the predetermined time of the refrigerator solenoid valve, and the motor will not be overloaded. But if the following situations occur, it will cause overload:
First of all, the power supply voltage is low, and the required torque cannot be obtained, so that the motor stops rotating;
Second, the torque limiting mechanism was adjusted incorrectly to make it greater than the stopping torque, which resulted in the continuous generation of excessive torque, which caused the motor to stop rotating;
Third, during intermittent use, the accumulated heat energy exceeds the allowable temperature value of the motor;
Fourth, due to some reasons, the circuit of the torque limiting mechanism has failed, resulting in excessive torque;
Fifth, the use environment temperature is too high, so that the thermal capacity of the motor is relatively reduced.