Small power DC motor - has permanent magnet excitation system with laminated rear circuit and rotor core with iron filling factor smaller than 0.9

摘要

The small d.c. motor has a permanent magnet excitation system surrounding the rotor. Its permanent magnet(s) have a soft ferromagnetic back circuit, and a laminated rotor core supports the armature windings. The excitation system's (14) permanent magnets have a relatively small-w.r.t. iron-natural remanent induction, and the rotor's laminated core(23) and/or the rear circuit(14) have an iron filling factor(f) much smaller than 0.9, and/or the tooth heads of the rotor core(23) are at least partly reduced. The laminations of the stator block can be at least partially separated from each other by a material of limited specific gravity. The magnetically-inactive intermediate spaces between the rotor plates can be formed as distancing discs.