| US 7,595,577 B2 | ||
| Brushless motor and electric power steering apparatus incorporating the same | ||
| Noboru Niguchi, Nara (Japan); Hirohide Inayama, Nara (Japan); Naotake Kanda, Nara (Japan); and Masaru Horikawa, Nara (Japan) | ||
| Assigned to JTEKT Corporation, Osaka (Japan) | ||
| Filed on Sep. 26, 2007, as Appl. No. 11/861,752. | ||
| Claims priority of application No. 2006-260023 (JP), filed on Sep. 26, 2006. | ||
| Prior Publication US 2008/0073995 A1, Mar. 27, 2008 | ||
| Int. Cl. H02K 1/00 (2006.01) | ||
| U.S. Cl. 310—216 | 11 Claims |
| 1. A brushless motor comprising:
an annular stator; and
a rotor having a plurality of permanent magnets alternately arranged in circumferential direction on the rotor to form poles,
and disposed within the stator to be rotatable with respect to the stator; wherein the stator includes a cylindrical yoke
and a plurality of teeth which are equal in size, are connected to the yoke as to extend therefrom toward the rotor, and are
disposed at even intervals in the circumferential direction, and
wherein a cogging torque of the brushless motor is minimized by setting a value for the width of each of the teeth in the
circumferential direction substantially equal to the value which is obtained by dividing outer diameter of the rotor by the
number of the teeth and multiplying the result of dividing by π/2.
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