DEVICE FOR AUTOMATICALLY OPENING AND CLOSING AIRTIGHT DOOR

摘要

PURPOSE:To simplify the adjusting operation of an airtight door by hydraulically opening or closing and sealing the door via a hydraulic circuit to thereby exactly airtightly seal the door against external pressure. CONSTITUTION:When a pump 6 is normally rotated to supply hydraulic oil to a pipe 12', a check valve 11 is opened to communicate the pilot unit 9a of a pilot control valve 9 with a tank to thereby switch the valve 9 and to open a ckeck valve 10 so as to move a piston 1c rightwardly to thus open a door. When the pump 6 is reversely rotated to supply the oil to a pipe 12, it moves the piston 1c leftwardly to thus close the door. A passage 15 communicates with a chamber 1b immediately before the piston 1c completes its closing stroke to thereby supply the oil to a door pushing cylinder 2 to cause its piston rod 2a to push the door into sealed state. When the door is thus sealed airthghtly, the cylinder 2 is shut off via a check valve 17 and second chock valve 11. Thus, even if large external pressure is applied to the door, the latter is still sealed due to non-compressibility of the oil.