Abstract: A commutator machine, in particular a small direct-current motor, has at least one pair of permanent magnets (11) retained on a magnetic short-circuit element (10), the permanent magnets being of a single-substance ferrite material or a multi-substance material having portions of high coercivity and high remanence along the periphery of an armature (15) rotating inside the stator (12). By selecting suitable ferrite materials, depending on the required excitation field intensity or the required demagnetization stability, and by the proposed dimensioning of armature diameter (d.sub.A), magnet thickness (D.sub.M) and thickness of the short-circuit element (D.sub.R), an optimal configuration of the motor is obtained by attaining the maximum possible capacity with the lowest possible weight.

Abstract: Three rotors disposed in axial succession on a common shaft are mounted to cooperate with a common stator having an annular laminated core coaxial with the shaft on which a three-phase stator winding is wound. The rotors are of two kinds, the middle one being of one kind and the outer ones of the other kind. These two kinds of rotors are, namely, the laminated core kind having a short-circuited squirrel cage conductor system and the synchronous having shell-shaped or ring-shaped permanent magnets mounted on a soft iron yoke which is in turn carried by a pierced hub of nonmagnetizable material. The squirrel cage rotor or rotors provide high starting torque, and the synchronous rotors provide good synchronous torque and a synchronous nominal speed. When the synchronous rotor is in the middle, the stator core may be subdivided into three parts to facilitate cooling.

Abstract: A permanent-magnet excited commutator motor, particularly a multipole small motor, has a stator yoke, an armature, two permanent magnet elements having a relatively low permeability, the permanent magnet elements having end tips with a gap formed between, the permanent magnet elements having one tip located forwardly as considered in the rotary direction of the armature, and a ferromagnetic auxiliary pole arranged on the stator yoke and having a relatively high permeability, the auxiliary pole being a U-shaped bracket having legs abutting against the end faces of the low permeability magnet elements, the bracket which forms the auxiliary pole being elastic and asymmetrical and formed as a holding spring, and legs of the bracket including a thicker leg and a thinner leg, where the thicker leg is formed as a stray web abutting against the permanent magnet tip lying forwardly in the rotary direction of the armature.

Abstract: A permanent magnet stator having two arcuate permanent magnet segments, each composed of two subsegments.

Abstract: An electric machine includes a flux-return yoke, a plurality of segmental permanent-magnet stator magnets mounted in the yoke with their outer peripheral surfaces engaging the inner peripheral surface of the flux-return yoke, and a wound rotor mounted for rotation in the space defined by the segmental stator magnets. Either the segmental stator magnets on their outer peripheral surfaces or else the flux-return yoke on its inner peripheral surface is provided with a structured surface portion adapted to properly position the stator magnets relative to the yoke. The structured surface portion has the form of a multitude of projections of identical height arranged in rows to form an array.

Abstract: A D.C. motor comprises a permanent-magnet stator including a flux-return structure and at least one permanent-magnet stator magnet mounted on the flux-return structure and also an armature mounted for rotation within the stator and having a circumferential succession of armature teeth. The rotary speed of the armature during operation of the D.C. motor is ascertained indirectly by sensing the variations in the stray flux of the motor at the exterior of the flux-return structure.

Abstract: To provide a magnet which has both the qualities of high remanence, or retentivity and coercive force, and is resistant to demagnetizing fields, the magnet is made in at least two zones of which the central or segmental zone is made of a magnetic material which has high remanence, whereas the end zone, or zones, is made of a magnetic material having high coercive force. This composite structure can be made by, for example, sequentially squeezing the different materials, in paste form, in a mold and then removing water, pressing, sintering and grinding the resulting structure.

Abstract: To test the flux of circular segmental permanent magnets for assembly in permanent magnet dynamo electric machines, typically electric motors, a gauge is made of soft iron having an inner segmentally circular soft iron core, on it a layer of non-magnetic material to simulate the air gap of the motor, space for the permanent magnet to be inserted, and a return soft iron yoke in magnetic circuit with the core. A measuring coil which is chorded is located on the gauge to sense the magnetic flux, and so placed on the core that it conforms, at least approximately, to the pitch angle of the armature winding of the dynamo electric machine with which the magnet is to be used.