| 摘要 |
PURPOSE:To prolong the life of a bearing in a standing-type vacuum pump being operated while the same is atmospherically pressured at its discharge side, by providing the drive shaft of a rotor in a pump mechanism portion with a balance ring wherein a permanent magnet opposed to another one set on a bearing fitting seat is embedded. CONSTITUTION:A standing-type vacuum pump has a drive shaft 4 rotatably supported through bearings 7, 8 vertically penetrating the inside of a housing 1 having an intake port 2 and a discharge 3. Said drive shaft 4 is provided with a motor-rotor 6a and respective upper and lower balance rings 15, 16, arranged with micro clearances to upper/lower bearing fitting seats 9, 10. Centrifugal compression pump rotor 11/stator 12 and circumferential flow compression pump rotor 13/stator 14 are provided in the housing 1, and the respective rotors 11, 13 are connected to the drive shaft 4. In this case, on each of the faces of the upper/lower bearing fitting positions 9, 10 opposite to each of the faces of the upper/lower balance rings 15, 16 is arranged each of paired permanent magnets A, B opposed to each other so that the magnet poles may attract each other. |
