The valve drive is a device that uses external power to start and close the valve. The transmission device is used to make the valve operation labor-saving, convenient, fast and reliable, and realize automatic control and remote control. The basic requirements of the valve transmission device are: torque or thrust can meet the opening and closing requirements of the valve, the stroke and torque control is accurate and reliable, the selection of the power source is suitable for the site conditions, the opening and closing actions meet the control requirements, and the device itself is light in weight.
According to the movement mode of the output shaft, the valve drive device is divided into three types: multi-turn rotation, two-way solenoid valve partial rotation and linear reciprocating type. The multi-turn type is suitable for valves whose stem or stem nut needs to be turned multiple times to fully open or fully close, such as gate valves, globe valves, etc. The output torque series of pressure solenoid valves are generally 40~10000 Nm (thrust 20~ 1100 kN). The partial rotary type is suitable for valves whose stem can be fully opened or fully closed within a circle, such as ball valves, butterfly valves, etc. The output torque is generally 125~125000 Nm. The linear type is suitable for valves that can be fully opened or fully closed only by linear reciprocating motion, such as solenoid valves. According to the power source, the transmission device of the valve can be divided into manual device, pneumatic device, hydraulic device, electric device, gas-liquid linkage and electro-hydraulic linkage, etc.
The first and simplest driving device of the valve is the hand wheel (handle). Due to the large-scale valve manufacturers and the automation of the production process, the demand for various valve actuators is also increasing. Valve transmission is an important part of industrial production automation.