| 摘要 |
PURPOSE:To have rapid and accurate pressure control by incorporating an automatic adjusting valve to control the pressure in the pressure circulating passage always constant, where a by-pass is formed in accordance with the piston response to change of the pressure. CONSTITUTION:In normal pressure condition, the pressure of helium gas, P flowing through the low-pressure side circulating passage 2b and divergent passage 5b is balanced with the combination force of the atmospheric pressure with the elastic force of an elastic member 10 to press a piston 9 upward, so that the piston 9 and piston rod 14 do not act. When a pressure P1 on the low pressure side exceeding a certain set value acts on the piston 9, it is depressed against the elastic force of the elastic member 10 and, at the same time, the piston rod 14 is depressed. This fall of piston rod 14 will cause formation of No.1 by-pass 17 which puts No.1 communication hole 19 in the piston rod 14 in communication with the pressure P2 through a ring-shaped passage 26a in a pilot piece 23, and then the pressure on the high pressure side P2, is discharged into a slide hole 28a and acts on the disc head 31. |
