Self-starting disk-type brushless motor with screw projection for generating cogging

摘要

A disk-type brushless motor comprises a 2p-pole magnet rotor (p represents an integer of 2 or more) having alternating N and S poles and a single position sensor element. A stator armature having an armature coil is formed on two conductors which contribute to the generation of torques and extend with an opening angle substantially equal to the width of each magnetic pole of the magnet rotor. A projection such as a screw for generating cogging to enable the self-start of the magnet rotor is disposed at a place somewhere short substantially by a width Pw4+nxPw wherein Pw is a width per pole of the magnet rotor, and n is a positive integer of 1 or more, from the conductor which contributes to the generation of torques toward the rotational direction of the magnet rotor.