A pneumatic actuator air flow control system, comprising:
- a pneumatic rotary actuator which includes an air reservoir and a vane housing which has an air-driven vane therein and the air reservoir has a larger volume ratio than the vane housing, wherein the pneumatic rotary actuator has a first positioning hole, a second positioning hole, a third positioning hole and a fourth positioning hole on its lateral surface, the first and second positioning holes connected to the air reservoir directly and the first positioning hole having a non-return valve;
- the third positioning hole connected with the vane housing through a first tube to drive the vane to an open position;
- and the fourth positioning hole connected with the vane housing through a second tube to drive the vane to a restored position to further close a valve body;
- and
- a solenoid air flow control valve, which is quickly switched between a fail-safe model and a double-acting mode under different circumstances;
- the solenoid air flow control valve including a flow control valve body, a pilot solenoid valve and a switch system to be formed as one unit, wherein the flow control valve body is connected with the pneumatic rotary actuator and directs air flow from an air source to the air reservoir of the pneumatic actuator, the pilot solenoid valve of the solenoid air flow control valve is adapted to control and change the air flow in and out the vane housing of the pneumatic rotary actuator to further change the rotating direction of the vane, and the switch system is adapted to manually switch between the fail-safe model and the double-acting model so that the solenoid air flow control valve has three controlling components;
- wherein the flow control valve body has an air reservoir air inlet port and an air reservoir outlet port to connect with the first and second positioning holes;
- a single-acting air flow path connected to the air reservoir air inlet port and a double-acting air flow path connected to the air reservoir outlet port, wherein the single-acting air flow path is connected with the switch system through a single-acting connector and the double-acting air flow path is connected with the switch system through a double-acting connector;
- and the flow control valve body further includes a first hole, a second hole, a third hole, a fourth hole, a fifth hole, an intermediate connecting port and a spool, wherein the first hole is an inlet hole while the third hole and the fifth hole are outlet holes, and the intermediate hole is located at the double-acting air flow path and according to whether the spool is compressed or not to change its position, the air flow from the air reservoir outlet port through the double-acting air flow path is determined to connect to the second hole or the fourth hole, wherein if the intermediate connecting port is connected to the second hole, the air flows through the second hole and the third positioning hole of the pneumatic rotary actuator into the pneumatic rotary actuator through the first tube to rotate the vane to its open position;
- and if the intermediate connecting port is connected with the fourth hole, the air flows through the fourth hole and the fourth positioning hole of the pneumatic rotary actuator through the second tube to rotate the vane to its restored position, wherein the pilot solenoid valve of the solenoid air flow control valve includes a first valve positioning hole, at least one second valve positioning hole and a plunger to control whether to open or close the first valve positioning hole, and the second valve positioning hole is located next to the first valve positioning hole, so that the air flows into the first valve positioning hole and is connected with the second valve positioning hole to a combining tube, and a ring-shape space directs the air in the combining tube to a compressed tube and the air flows from the compressed tube through the switch system into the flow control valve body to compress the spool, wherein the plunger is adapted to open or close the first valve positioning hole through the pilot solenoid valve or through a manual override and determine whether to connect the second valve positioning hole, to the compressed tube according to whether the first valve positioning hole is open or closed, and the switch system is connected with the first valve positioning hole in the pilot solenoid valve through a connecting path, and has a switch spool with axial movement to determine whether the air flows from the double-acting air flow path through the double-acting connector to the switch system of the double-acting model or the air flowing from the single-acting air flow path through the single-acting connector to the switch system of the fail-safe model.