Patent ID: 7717684

Claim:
A turbo vacuum pump comprising: a casing having an intake port; a pump section comprising rotor blades and stator blades housed in said casing; bearings for supporting said rotor blades; a motor for rotating said rotor blades; and a rotating shaft comprising a first rotating shaft to which said rotor blades are attached, a second rotating shaft to which a motor rotor of said motor is attached, and a shaft fastening portion for coupling said first rotating shaft and said second rotating shaft; wherein material of said first rotating shaft is different from material of said second rotating shaft; and said rotor blade attached to said first rotating shaft comprises a centrifugal drag blade having a plurality of spiral vanes, and the surface of said centrifugal drag blades faces the surface of said stator blade so that a gas is compressed and evacuated from an inner diameter side toward an outer diameter side of said centrifugal drag blade by the interaction of said centrifugal drag blade with said stator blade.