Patent ID: 6075774
Filing Date: 2000-06-13
Classification: H03M,H04L

Abstract:
A self-starting brushless electric motor, comprisinga ferromagnetic first motor part including a plurality of first poles arranged in spaced-apart relation in a first pole row,a ferromagnetic second motor part including a plurality of second poles arranged in spaced-apart relation in a second pole row,a bearing supporting the first motor part and the second motor part for relative movement with the first pole row confronting the second pole row across an air gap, anda winding on the first motor part comprising for each winding phase a first winding coil arranged in association with a first pole group of the first pole row to produce a magnetic field linking the poles of the first pole row and the second pole row through said first pole group upon energization of said first winding coil,the first pole row and the second pole row constituting a pole system comprising first-type and second-type poles, a first-type pole being a reluctance pole and a second-type pole being a permanent-magnet pole which is polarized transversely to the air gap,at least one of the first poles and second poles including a magnetic asymmetry providing a preferential relative direction of movement of the motor parts upon energization of the winding,wherein the motor parts have magnetically unbalanced relative positions in which a first pole of the first pole row is magnetically aligned with a second pole of the second pole row, and there is no other pole on the first motor part which is polarized oppositely to the first pole of the first pole row, which belongs to the same winding phase as the first pole of the first pole row, and which is also aligned with any other pole of the second pole row,wherein the first motor part includes an auxiliary pole adjacent to the second motor part, andwherein said auxiliary pole in said unbalanced relative positions of the motor parts presents a path for returning to the first motor part magnetically unbalanced flux which is passed to the second motor part from said first-mentioned aligned pole of the first pole row.