1. Core driving mechanism
Pneumatic actuator function
The piston in the cylinder is driven by compressed air, and the output shaft drives the ball to rotate 90° to open and close the valve or switch the flow direction.
Pneumatic actuators are divided into double-acting (requires two-way air supply) and single-acting (spring reset), and the direction of action is controlled by switching the air path through the solenoid valve.
Ball rotation and flow channel control
The ball is equipped with an L-shaped or T-shaped channel. When rotating, the alignment direction of the channel and the valve body is changed to achieve the diversion, confluence or flow direction switching of the medium.
L-type three-way ball valve: connects two vertical channels and cuts off the third channel, which is suitable for medium flow direction switching (such as A→B or A→C).
T-type three-way ball valve: can realize any combination of three channels (such as A+B→C or A→B+C), suitable for diversion or confluence control.
2. Structural characteristics and sealing principle
Valve body and sealing structure
The valve body is made of stainless steel (such as 304, 316L), which has strong corrosion resistance and is suitable for acid and alkali media and high temperature environments (maximum ≤450℃).
The sealing surface adopts metal hard seal (such as stainless steel + hard alloy) or soft seal (such as PTFE), and the ball is pressed by the mechanical force of the valve seat to achieve zero leakage.
Friction control and self-cleaning design
When opening, the ball instantly leaves the valve seat, and when closing, it only needs to press the final position to reduce the wear of the sealing surface.
During the flow of the medium, the fluid is evenly flushed along the surface of the ball 360° to remove impurities and prevent local erosion.
3. Control process and performance advantages
Signal input and action response
After receiving the control signal (such as 4~20mA or switch quantity), the solenoid valve switches the gas path and drives the actuator to complete the opening and closing action, with a response time of ≤1 second.
When equipped with a positioner, the opening can be accurately adjusted (error ≤±1%) to meet the flow ratio control requirements.