Pneumatic actuators

Valve adopts pneumatic actuator has the advantage of closing fast, when the moment is small can be. S within the opening and closing. Pneumatic actuators does not damage to the environment, leakage, good adaptability to the work environment, in the inflammable, explosive, harsh environments, such as strong magnetic and strong radiation is not affected. Pneumatic actuators can be in power, oil source, fault signal to reset the valve to a safe location in advance, make the valve in the system are protected. However, due to the low air pressure is generally so actuator is bigger. Due to the compressibility of air, the action of pneumatic stability is a bit poor. Types and application of pneumatic actuators according to the transmission mode can be divided into gear and rack type and fork type. According to the air supply mode can be divided into single acting, double-acting, in single acting and gas can be divided into open type and close type. According to the principle of pneumatic types can be divided into external regulation and switch, switch type and can be divided into the normal, fast clearance ( Open) Type. Pneumatic actuators should be chosen according to the condition of different demand. Pneumatic actuator of A cavity into gas pressure to push the piston compression spring, rack drive gear for counterclockwise movement drive valve opens at the same time, when the actuator of A cavity pressure gas expelled the spring release can promote piston rack and driven gear clockwise motion, drive the valve closed. Because it is a pressure valve opens, so this drive form is also known as open. When the system needs the valve closed when loss of air pressure, can choose this way. When the system in the loss of air pressure to open the valve, the actuator spring around the cylinder and the cylinder exchange can be realized. Due to the pressure valve is closed at this time, this kind of drive form also known as gas type. When double acting type actuator bubbled into A cavity when the gas pressure to push the piston rack and pinion drive A counterclockwise movement valve open, when B pass into the cavity of the actuator gas pushes the piston rack and pinion for clockwise motion drive valve shut off. Double-acting actuators can only realize the loss of electricity and signal back to the safety valve position or stay in situ, when loss of air pressure does not guarantee the location of the valve. But the actuators with double acting and single acting actuators, compared to small volume under the condition of the same output torque. Fork type actuator pneumatic principle and gear rack type is the same, but the fork type actuator output torque curve and the gear rack type actuator output torque curve are different. Gear rack type actuator output torque is a constant value, and fork type actuator output torque is a curve, the output torque is bigger when ° and °. Appropriate change fork centerline with the centerline of the sliding block fork groove Angle Q torque curve of different shapes can be obtained.