Positioning control mechanism for double-acting air cylinder

A positioning control mechanism for a double-acting air cylinder comprising:

• a double-acting main cylinder having a first pressure chamber and a second pressure chamber on both sides of a piston in that the piston is reciprocated by supplying air to these pressure chambers;
• a length measurement sensor for measuring an acting position of the piston along the entire stroke of the piston;
• an air supply section having an air source;
• a main air circuit interposed between the air supply section and the main cylinder;
• and
• a controller for electrically controlling the main air circuit,
• wherein the main air circuit includes a first air flow path and a second air flow path connecting between the air supply section and the first and second pressure chambers of the main cylinder, respectively;
• a two-port first supply solenoid valve and a two-port second supply solenoid valve connected to the first and second air flow paths so as to intersect them, respectively;
• and a two-port first exhaust solenoid valve and a two-port second exhaust solenoid valve connected to the first and second pressure chambers so as to intersect the flow paths between the atmosphere and the first and second pressure chambers, respectively, and
• wherein the controller includes inputting means electrically connected to the length measurement sensor and the solenoid valves for inputting a target acting position of the piston, and the controller is configured to move the piston to the target acting position and stop it at the position by on-off controlling the solenoid valves on the basis of the compared results between target position information inputted by the inputting means and measured position information measured by the length measurement sensor:
• when the piston is advanced, the first supply solenoid valve and the second exhaust solenoid valve are turned on, while the second supply solenoid valve and the first exhaust solenoid valve are turned off, so that the air supply section is communicated with the first pressure chamber, and the second pressure chamber is opened to the atmosphere;
• when the piston is backed, the second supply solenoid valve and the first exhaust solenoid valve are turned on, while the first supply solenoid valve and the second exhaust solenoid valve are turned off, so that the air supply section is communicated with the second pressure chamber, and the first pressure chamber is opened to the atmosphere;
• and when the piston is stopped at the target position and maintained at the stopped position, the entire solenoid valves are turned off so as to confine air within the both pressure chambers.