A rotor for an electric motor or generator

Abstract

An external rotor for an electrical motor or generator (e.g. a wheel motor) has poles, each comprising a pair of rare earth permanent magnets 30 inclined towards each other in V formation. Soft ferromagnetic elements 32, 33 are arranged to retain the magnets, element 32 being mounted by its outer surface 35 to the inner rim of the rotor by means of adhesive or mechanical connectors, magnet surfaces 36 of each of the magnet pairs being adhesive mounted in V formation on the inclined inner surface of the element 32. Wedge shaped elements 33 are secured to the opposite face 37 of the magnets 30, and are arranged with respect to adjacent elements with an air gap 34 between respective end potions of the elements 33. Surface 38 of the element 33 forms the pole surface. The method of assembly may comprise magnetically holding the elements 33 to a former, securing the magnets 30 thereto, attaching the element 32 to the other faces of the magnets and subsequently mounting the circumferential potion of the rotor over element 32. The gap 34 may comprise a low reluctance material and the V assembly may be replaced by a single C shaped magnet.

Description

technical field [0001] The invention relates to rotors, in particular rotors for electric motors or generators. Background technique [0002] Motors work as follows, current carrying wires will experience a force in the presence of a magnetic field. When the current-carrying wire is placed perpendicular to the magnetic field, the force acting on the current-carrying wire is proportional to the magnetic flux density of the magnetic field. Typically, the force acting on a current-carrying wire is generated in an electric motor in the form of torque. [0003] Examples of known types of motors include induction motors, brushless permanent magnet motors, switched reluctance motors and synchronous slip ring motors, which have a rotor and a stator as is well known to those skilled in the art. [0004] Since the force acting on the current-carrying wires and thus the torque on the motor is proportional to the magnetic field flux density, it is best to use a motor with as high a to...

AI Technical Summary

Problems solved by technology

However, this design for an inner rotor that utilizes a V-shaped magnet configuration is not suitable for motors with outer rotors, where the rotor typically does not have enough radial space to utilize a one-piece rotor iron components to accommodate the angularly offset rare earth magnets used in the inner rotor design

Also, for these designs, flux leakage can be relatively high

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