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:
Nov. 24, 2009

Filed:

Jul. 13, 2007
Applicants:

Hirofumi Atarashi, Wako, JP;

Hiromitsu Sato, Wako, JP;

Masanari Fukuchi, Wako, JP;

Masaaki Kaizuka, Wako, JP;

Inventors:

Hirofumi Atarashi, Wako, JP;

Hiromitsu Sato, Wako, JP;

Masanari Fukuchi, Wako, JP;

Masaaki Kaizuka, Wako, JP;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02P 25/00 (2006.01);
U.S. Cl.
CPC ...
Abstract

A change in torque produced by a motor having two rotors is reduced when the motor operates in a low-velocity and low-torque operational state. The motor has a first rotor and a second rotor, each of which has a permanent magnet, and an output shaft capable of rotating integrally with the first rotor. The second rotor can relatively rotate with respect to the first rotor by a driving force from a phase difference changing driving device, and the phase difference between the rotors (rotor phase difference) can be changed by the relative rotation of the second rotor with respect to the first rotor. When the values of the torque and the rotational velocity of the motor lie within a predetermined region in the proximity of 0, the phase difference changing driving device adjusts the rotor phase difference to a predetermined phase difference for which the strength of a composite field of the permanent magnets is lower than a maximum strength.


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