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Title:
BRUSHLESS DC MOTOR, MAGNETIC BEARING DEVICE AND TURBOMOLECULAR PUMP
Document Type and Number:
Japanese Patent JP3169892
Kind Code:
B2
Abstract:

PROBLEM TO BE SOLVED: To provide a turbomolecular pump having a DC brushless motor provided with a detecting mechanism for number of revolution of a simple structure.
SOLUTION: A pickup coil 303 for detecting the magnetic flux generated by a permanent magnet 301 of a DC brushless motor 30 is incorporated in the motor. Specifically, a small-sized, low-cost, simple and sturdy pickup coil is arranged in the space between the permanent magnet (rotor) 301 of the DC brushless motor 30 and a motor drive coil (stator coil) 302. When the magnetic flux generated by the permanent magnet 301 is detected with the pickup coil 303, it is converted into the number of revolution signals of the DC brushless motor in a sequence control circuit to and monitors whether it is excessive in speed. If excess speeding is detected, a breaking command is given to a power supply breaker. By forcibly stopping the supply of electric power, the DC brushless motor is forced to stop.


Inventors:
Kawashima, Toshiaki
Application Number:
JP1998000134405
Publication Date:
March 16, 2001
Filing Date:
April 28, 1998
Export Citation:
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Assignee:
SEIKO SEIKI CO LTD
International Classes:
F04D27/00; F04D19/04; F16C32/04; H02K7/09; H02K29/08; H02P1/04; H02P3/04; H02P6/00; H02P6/06; H02H7/093; (IPC1-7): H02K29/08; F04D19/04; F04D27/00; F16C32/04; H02K7/09; H02P3/04
Attorney, Agent or Firm:
川井 隆 (外1名)



 
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