Salient pole stator and slotted rotor machine - has interpolar and slot opening filling strips to give cylindrical surfaces to reduce windage noise

摘要

The motor is for domestic equipment, e.g. washing machines. Where salient pole machines are used, typically commutator motors, the interaction between the space between stator poles and the armature slot openings can give rise to considerable windage noise where the fundamental frequency is proportional to speed. To assist in suppressing the component of noise it is desirable to have smooth, cylindrical surfaces on stator and rotor. In order to achieve the required surface, the space between pole shoes is closed by fitting non-metallic plates between the pole tips. The plates are profiled to continue the contour of the pole face. Similarly the armature slots are closed with wedges whose profile is such that they extend to the armature periphery. The wedges preferably leave a minimum gap between the sides and the tooth tips.