| 摘要 |
PROBLEM TO BE SOLVED: To enhance durability in a vacuum opening and closing valve having a gap between the peripheral surface of a piston and the inside circumferential surface of a cylinder sealed tightly with a bellofram following operation of a piston motions and opened and closed by driving the piston with fluid. SOLUTION: The vacuum opening and closing valve 10 is connected between a vacuum vessel 2 and a vacuum pump 5, and controls the vacuum pressure in the vacuum chamber 2 by changing the degree of opening of an O-ring 79 as a valve element relative to a valve seat 73. The specified gap between the peripheral surface of the piston 40 and the inside surface of the cylinder 30 is tightly sealed with the bellofram 50 following movement of the piston 40, and can be opened and closed by driving the piston 40 with fluid. The bellofram 50 is formed with a prescribed inclination angleθ2, the periphery of the piston 40 is formed with a prescribed inclination angleθ, and the inside diameter of the bellofram abutting to the piston when the valve element is positioned abutting to the valve seat is equal to the outside diameter of the piston. COPYRIGHT: (C)2009,JPO&INPIT
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