The electric actuator is generally divided into rotary actuators and linear actuators according to their motion modes. Both of them are composed of servo amplifier and actuator, one of which outputs angle (torque) and one of which outputs displacement (thrust) . The function of the linear actuators and rotary actuators electric actuators is to receive the standard current signal of 0~10, 4~20 mA or 1~5 V voltage sent by the regulator or other instruments, which will become displacement thrust or angle torque after passing through the actuator to operate switches, valves, etc. to complete the task of automatic adjustment.
Most of the rotary electric actuators and linear electric actuators are modified on the basis of the multi turn electric actuator type: based on the multi turn type, a 0~90 °rotary electric actuator is composed of a worm gear two-stage reduction box; A linear electric actuator is composed of a screw rod component.
Difference:
1. Different industries: The rotary actuators electric valve is used to control the 90 degree rotation so as to achieve the on-off of the valve. The rotary electric actuator is used together with the ball valve, plug valve and butterfly valve, and can rotate for a quarter or more of a turn from opening to closing. Rotary electric valve controllers are used in power industry, high-power switch gear and packaging applications.
Linear actuators is to realize the up and down movement of the valve plate, which is usually used on equipment with high degree of automation.
2. Different types: Rotary actuators valves include electric ball valves, plug valves, electric butterfly valves, and other rotary actuators valves. Linear actuators valve includes stop valve, electric gate valve, slide valve, etc.
3.The movement mode of the valve core is different: the valve core of the rotary actuators valve rotates with the valve stem at an angle perpendicular to the valve stem. The linear actuators valve drives the valve core to rise and fall vertically to the valve stem through the valve stem.
Flow resistance and kv value
The medium flow path of the linear actuators valve is complex and S-shaped, so the flow resistance is large and the flow capacity is small, so the flow coefficient Kv is small. The medium flow path of Rotary Actuators valve is simple, so the flow resistance is small, the flow capacity is large, and the Kv value is large (the kv value is 1.5-3 times larger than that of linear actuators valve).
Sealing performance
The linear actuators double seal valve has upper and lower valve seats, but the axial size of the double seal valve core cannot be absolutely equal to the axial size of the two valve seats. When the upper valve core and valve seat contact, there is still a gap between the lower valve core and valve seat, or when the lower valve core and valve seat contact, there is still a gap between the upper valve core and valve seat. As a result, the leakage of the double seal valve is large, coupled with the impact of thermal expansion, this situation is more serious. For rotary actuators valves, especially ball valves, the leakage is small because the valve core is spherical, tangent to the sealing surface and in good contact. Packing with better sealing performance can also be used to improve the sealing performance of rotary actuators by 2-3 times compared with that of linear actuators.
