| 摘要 |
PURPOSE: To stabilize a shaft rotating speed at a high speed by surrounding a shaft rotatable at a high speed by a first multistage seal, constituting so as to endure the whole pressure drop between a first high pressure environment and a second high-vacuum environment, and arranging a second single-stage seal in series to the first seal on the shaft. CONSTITUTION: A multistage seal is designed and constituted so as to have sufficient pressure performance to endure the whole pressure drop between an environment under first pressure such as atmospheric pressure or a high- pressure area 16 and an environment under second pressure such as a high vacuum in a vacuum chamber 14. A second single-stage ferrofluidic seal includes a magnet 43, polar pieces 44, 45, a magnetically permeable shaft 15 and annular gaps 46, 47, and surrounds the shaft 15 on the high-vacuum side of a first mutistage seal. A region between the first multistage seal and a second single- stage seal becomes an annular sealed intermediate area 50 so that air is released to atmospheric pressure or pressure between the high pressure area 16 and a high vacuum of the vacuum chamber 14. |
