| 摘要 |
The present invention provides a vacuum pump capable of preventing dropping of a pump at the time of occurrence of an abnormality of the pump, and performing a rapid pump changing operation. A step (1a) is provided at a peripheral end portion of an upper surface of a pump case to form a flange portion (20), and the vacuum pump comprises: an auxiliary ring (22) attached and fitted to the upper surface of the flange portion, the surface of which is integrated with the upper surface of the pump case; a bolt insertion hole (34) formed so as to pass through the upper surface and the lower surface of the auxiliary ring; a first bolt insertion hole (28) and a second bolt insertion hole (26) formed so as to pass through the upper surface and the lower surface of the flange portion; a bolt (36) inserted into the bolt insertion hole of the auxiliary ring, screwed in and fixed to the lower portion opening peripheral end of a chamber positioned at the side opposing the upper surface of the pump case; a bolt (40) inserted into the first bolt insertion hole of the flange portion, screwed in and fixed to the auxiliary ring; and a bolt (38) inserted into the second bolt insertion hole of the flange portion, screwed in and fixed to the auxiliary ring, and a shaft diameter of which being set small as compared with the bolts. <IMAGE> |
