Vacuum pump with pump rotor pairs and permanent magnet motor

摘要

A vacuum pump has a casing having an inlet port and an outlet port, and a pair of confronting pump rotors which are provided inside the casing and synchronously rotatable for drawing in a gas from the inlet port and discharging the gas from the outlet port. A motor for rotating the confronting pump rotors is a permanent magnet motor having a stator and a motor rotor. The motor rotor has an iron core and permanent magnets disposed within the iron core.