Vacuum pump

A vacuum pump comprising:

• a casing, the casing having an inlet port for sucking gas from outside and an outlet port for exhausting the gas to the outside;
• a turbo-molecular-pump mechanism, the turbo-molecular-pump mechanism being disposed in the casing and including rotor blades and stator blades alternately arranged in multiple stages in an axial direction;
• a thread-groove-pump mechanism, the thread-groove-pump mechanism being disposed in the casing and being connectedly disposed on an exhaust side of the turbo-molecular-pump mechanism;
• a bearing, the bearing rotatably holding a rotating portion of the turbo-molecular-pump mechanism and a rotating portion of the thread-groove-pump mechanism;
• and
• a motor portion configured to rotate the rotating portions,
• the vacuum pump further comprising:
• first temperature regulating means configured to regulate cooling of the turbo-molecular-pump mechanism;
• and
• second temperature regulating means configured to regulate heating of the thread-groove-pump mechanism, wherein
• the turbo-molecular-pump mechanism is divided into an upper-stage-group gas transfer unit that is disposed downstream from the inlet port and is cooled by the first temperature regulating means, and a lower-stage-group gas transfer unit that is disposed upstream of the thread-groove-pump mechanism and is heated by the second temperature regulating means, and
• heat insulating means is provided between the first temperature regulating means and the lower-stage-group gas transfer unit, wherein a portion of the heat insulation means extends axially adjacent the lower-stage-group gas transfer unit.