Principle of pneumatically controlled three-way valves

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Three-way valves are widely used in the chemical, plastics, and casting industries; in the past, they were mostly operated manually. With the development of science and technology, automatic control technology has been widely applied in various production fields, and the pneumatically controlled three-way valve was developed under such circumstances. Pneumatically controlled three-way valves can achieve automatic control during the production process through electro-pneumatic control technology. 1. Cylinder block 2. Piston 3. Piston rod 4. Cylinder head 5. Roller assembly 6. Screw guide sleeve 7. Protection cover 8. Valve stem 9. Adjustment screw sleeve 10. Screw sleeve housing 11. Valve body 12. Valve port 13. Valve core. The working principle of the pneumatically controlled three-way valve is as follows: The pneumatically controlled three-way valve consists of three parts – the upper part, the middle part, and the lower part. The upper part is a double-acting cylinder; the middle part is a rotating component; and the lower part is a three-way ball valve. When piston 2 is at the upper end of the cylinder, chamber I is connected to chamber II. When air enters the cylinder from P1, piston 2 moves downward under the effect of air pressure; piston rod 3 drives roller 5 to move downward along the guide groove in the spiral guide sleeve, thereby causing spiral guide sleeve 6 to rotate. When piston 2 moves downward to the lower end of the cylinder, the spiral guide sleeve rotates by 90°, which in turn causes the ball valve stem 8 to rotate by 90° as well, and valve core 13 also rotates by 90°. As a result, chamber I becomes isolated from chamber II, while chamber I becomes connected to chamber III. Conversely, when the air source enters the cylinder from P2, the piston 2 inside the cylinder moves upward under the action of air pressure; the piston rod 3 drives the roller 5 to move upward, causing the screw guide sleeve 6 to rotate. When the piston 2 moves upward to the upper end of the cylinder, the screw guide sleeve rotates 90° in the opposite direction, which in turn causes the ball valve stem 8 to rotate 90° in the opposite direction as well, and the valve core 13 also rotates 90° in the opposite direction. As a result, chamber I is separated from chamber III, while chamber I becomes connected to chamber II. The pneumatically controlled three-way valve can be controlled by a pneumatic solenoid directional valve to regulate the direction of air flow in and out of ports P1 and P2. Pneumatically controlled three-way valves can handle fluids, gas-liquid mixtures, and semi-fluids.