U.S. Philips Corporation

Jan Janson

Henricus M Van Hout

Johannes H Janssen

Robertus I Van Steen

An electrical multipole machine comprises a first machine section (1), a second machine section (3) and a machine shaft (5), about which one machine section is rotatable relative to the other machine section. The first machine section comprises an annular permanent-magnet body (11) having a plurality of adjacent pole pairs (N; S). The second machine section comprises a lamination assembly (25) having teeth (27-35) and coils (37-45). The teeth comprise tooth surfaces (47-55) which are geometrically spaced from one another by slots (57-65) and from the magnet body by an air gap (67). Near the air gap the slots extend in a tangential direction over at least 80 electrical degrees and at the most 90 electrical degrees, or over at least 130 electrical degrees and at the most 150 electrical degrees. The ratio between the number of poles and the number of teeth is either 4:3 or 2:3.

Three-phase electrical machine with reduced cogging torque

An electric motor comprises a rotor (20), an annular stator coils (44A, 44B), and a stator body having a central stator portion (24A, 24B) which is disposed coaxially around the rotor shaft (18) and a number of stator teeth. The stator teeth each have a proximal portion (28) secured to the central stator portion and a distal portion (30) having an axial pole face (30A) adapted to cooperate with an axially magnetized ring (20A) of the rotor. Half of the stator teeth also comprise an axial tooth portion (42) which extends between the proximal portion and the distal portion of the relevant stator tooth, because the proximal portions and the distal portions of these teeth are disposed in different axially spaced radial planes. The stator coils are disposed in the space between the central stator portion and all the axial tooth portions.

Electric motor having formed stator sections with coplanar teeth

A flat collectorless motor is described whose rotor has been provided with an axially magnetized annular magnet which cooperates with axial bounding surfaces of the stator poles outside the stator coil ends, which enables the axial height of the stator iron to be reduced without reducing the effective surface area of the stator teeth. This construction enables Hall elements to be mounted on a p.c. board, which Hall elements are arranged in the main field of the rotor magnet.

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Eindhoven, Netherlands

Jan Janson