The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Dec. 21, 1999

Filed:

Mar. 06, 1998
Applicant:
Inventors:

Hiroshi Ikuta, Chiba, JP;

Fumiharu Sudo, Chiba, JP;

Toru Nakahara, Chiba, JP;

Mitsuhiro Ueno, Chiba, JP;

Yuji Shishido, Kanagawa, JP;

Assignee:
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B / ; H02K / ;
U.S. Cl.
CPC ...
360 9912 ; 310 51 ;
Abstract

A magnet is provided which holds spherical balancers in the central portion of a rotor when the rotation of the rotor is stopped. When rotations of the rotor is started, a larger torque T.sub.0 is transmitted from the rotor to the balancers. Thus, the balancers quickly start rotating. When the rotor rotates at high speed, the centrifugal force separates the balancers from the magnet and moves the same to the outer wall portion of the rotor. At this time, a torque T.sub.0 which is transmitted from the rotor to the balancer is reduced so that the balancers are moved in the circumferential direction. Thus, the automatic aligning operation is performed. The number (n) of the balancers is made to be a value obtained by the following equation:


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