| 摘要 |
PURPOSE:To improve durability of both pressure contact members with less wear by providing a valve seat having a beltlike passage port at the position facing the circumference of each of both the pressure contact members and having the curved face approximately equal to the radius of curvature of roll of each pressure contact member. CONSTITUTION:Each contact member 6 is brought into close contact with a beltlike member 2 by reciprocating each support member 5 to carry out vacuum seal at the circumference of the beltlike member 2. In this case, until the circumferential face 10 of the pressure contact member 6 is brought into contact with the curved face of a valve seat 13, the member 6 moves while turning smoothly along the valve seat 13 while being supported playably in each long hole of a support member 5. When the circumferential face 10 of the member 6 comes to contact with the curved face 12 of the valve seat 13, the member moves being guided by the long hole 8 so that the circumferential face 10 and the curved face 12 are brought into contact with each other. The part between the circumferential face 10 of the pressure contact member 6 and beltlike member 2, and the circumferential face 10 and the valve seat 13 can be shut completely without difficulty, and thereby the part between the atmospheric side (a) and the vacuum side (b) is vacuum sealed. |
