| 摘要 |
A vacuum pressure control apparatus includes a vacuum proportional opening and closing valve 18 which is disposed on a pipe connecting a vacuum chamber 11 and a vacuum pump 19 and changes its opening to control the vacuum pressure in the vacuum chamber 11, and a pressure sensor 17 which measures the current vacuum pressure in the chamber 11. The vacuum proportional opening and closing valve 18 has a valve seat 36 and a valve member 33 provided with an O-ring 35 which is made contact with or separate from the valve seat 36. The vacuum pressure control apparatus configured as above controls the pressure in the chamber 11 by changing an elastic deformation amount of the O-ring 35 which is in contact with the valve seat 36 and thereby changing the flow quantity of gas leaking between the valve seat 36 and the O-ring 35.
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