STP-H803/H1303 Series Instruction Manual
2
Operation Principle of the STP Pump
Installation
The STP series pump is a series of a magnetically-levitated turbomolecular
pumps, featuring the following:
•
Oil free
•
Low vibration
•
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.
The STP pump is configured with a screw channel pump and turbine blade
together in the lower side of rotor blade (1) for high-throughput even at a low
vacuum range (a few hundred Pa (a few Torr)).
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 or air cooling during baking and gas pumping. Taking into consideration
a breakage of magnetic bearings, touch down bearings (7) coated with solid
lubrication have been installed. They do not contact with the rotor during the
rated operation.
A radial sensor, an axial sensor, a rotational speed 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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