VACUUM PUMP UNIT

摘要

The present invention relates to a dry vacuum pump unit capable of achieving ultimate pressure of about 1 Pa. The vacuum pump unit includes a main pump (15) disposed at an outside-pressure side, and a booster pump (16) disposed at a vacuum side. The booster pump (16) and the main pump (15) are coupled in series. The booster pump (16) has a higher pumping speed than that of the main pump (15). Each of the main pump (15) and the booster pump (16) includes a pair of pump rotors (52a and 52b), a casing (50) having an inlet port and an outlet port, and a pair of magnet rotors (54 and 54) rotatable with the pair of pump rotors.