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.
Patent No.:
Date of Patent:
Jun. 13, 2000
Filed:
Nov. 18, 1997
Gary D Lorenz, Acton, MA (US);
Charles Lee, Ashland, MA (US);
3Com Corporation, , US;
Abstract
A self-starting brushless electric motor having: a first motor part (stator) (11) with poles (15S, 16A) arranged in a first pole row, said poles comprising for each winding phase a pole group (13) including a pole pair consisting of a reluctance pole (15S) and a permanent-magnet pole (16A), only one such pole group being provided for each winding phase; a second motor part (rotor) (12) movable with respect to the first motor part (11) and provided with reluctance poles (18A) arranged in a second row of poles opposite to the first row of poles; and a magnetizing winding (17) on the first motor part (11). At least one of the pole rows exhibits a magnetic asymmetry providing a preferential relative direction of movement of the motor parts (11, 12) upon energization of the winding. The poles (15S, 16A) of the pole pair of the first pole row are spaced-apart such that whenever a pole of the pair is magnetically aligned with a pole (18A) of the second pole row, the other pole of the pair is magnetically misaligned with the next adjacent pole of the second pole row. A ferromagnetic auxiliary pole means (20) is provided on the first motor part (11) and positioned such that whenever the permanent-magnet pole (16A) of said pair is magnetically aligned with a pole (18A) of the second pole row, the auxiliary pole means (20) confronts at least one of the other poles of the second pole row across an air gap (19) which separates the pole rows.