Brushless external rotor motor - ensures small spacing between magnet and motor shaft with iron free coil around magnet

摘要

The motor has a magnet (1), an iron yoke (2) and a coil (3). The latter is surrounded by the yoke (2) and is fixed in a housing (8) so that it cannot rotate. A motor shaft (4) is rotatably positioned in the housing (8). The magnet(s) (1) and yoke (2) are fixedly connected to this shaft (4). The coil (3) contains no iron. It surrounds the magnet(s) (1) at least over most of its axial length with a space between the coil (3) and the magnet(s) (1). The coil (3) preferably extends into an annular space (9) between the yoke (2) and the magnets (1). ADVANTAGE - Reduces eddy current losses so increases motor efficiency. Has small moment of inertia.