METHOD OF OPERATING TWO SPINDLE TYPE VACUUM PUMP BASED ON NORCY PRINCIPLE AND TWO SPINDLE TYPE VACUUM PUMP ADAPTED FOR EXECUTING SAID METHOD

摘要

PURPOSE: To effect pump scavenging reasonably by supplying scavenging gas to a suction volume transported to an opening of a scavenging gas conduit after an inlet opening of the vacuum pump is closed, and effecting supply control by using the rotors at the outlet side of the rotor pairs. CONSTITUTION: In a three-staged vacuum pump 1 with three pairs of rotors 6, 7 arranged axially on two shafts 2, 3, each pair of rotors 6, 7 comprises a protrusion 38 and a notch 39 respectively supported in a suction chamber 12 for rotating synchronously in a non-contact manner. The rotors 6 are controlled by an inlet opening 35 and the other rotors 7 are controlled by an outlet opening 42. In this case, scavenging gas (nitrogen gas, etc.), is supplied into a suction volume 44 transported to an opening 45 of a scavenging gas conduit leading to a gas bomb after the inlet opening 35 is closed. After that, the outlet opening 42 is opened, the supply of scavenging gas is controlled by using the rotors at the outlet side.