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STP-H600/H1000 Series Instruction Manual
11 Operation Principle of the STP Pump
The STP-H600/H1000 is a series of magnetically-levitated turbomolecular pumps, featuring
the following:
l Oil free
l Low vibration
l High reliability
The STP pump is configured so that rotor blade (1) and stator blade (2) are aligned
alternately in the axial direction. Gas molecules are pumped from the inlet port to the
outlet port by the high speed rotation of the rotor.
By uniting the rotor blades and the sleeve lower, the STP pump has a large capacity
allowing it to be used in a wide variety of applications. Rotor blade (1) is supported by the
magnetic bearing without mechanical contact. Therefore, the STP pump requires no
lubrication oil unlike conventional turbomolecular pumps using ball bearings.
The magnetic bearing consists of 5 pairs of active magnetic bearings. The rotor is
supported in the radial direction by 4 pairs of radial direction active magnetic bearings that
consist of radial sensor (3) and radial electromagnet (4). A pair of axial direction active
magnetic bearings consists of axial sensor (5) and axial electromagnet (6) to support the
rotor in the axial direction. Because the rotor is supported without mechanical contact, it
can rotate at low vibration.
There is less heat generated from magnetic bearings because there is no friction. Therefore
the STP pump requires no cooling. However, the STP pump requires water cooling during
baking and gas suction. Taking into consideration a breakage of magnetic bearings, touch
down bearings (7) and (8) coated with solid lubrication have been installed. They do not
contact with the rotor during the rated operation.
A radial direction sensor, a rotation sensor and a temperature sensor always monitor the
magnetic bearing as well as the rotor. If an abnormality/error occurs, the rotor will stop.
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