Patent ID: 6172442
Filing Date: 2001-01-09
Classification: H02K

Abstract:
A disk-type brushless single-phase DC motor comprising:a flat annular rotor magnet fixedly mounted to a rotor by a rotor magnet yoke and provided with a plurality of alternating N and S poles having the same area, the number of the poles corresponding to 2P, where P is an integer not less than 1;a stator interfacing with the rotor magnet, thereby generating an electromagnetic force, the stator comprising:a stator yoke arranged coaxially with the rotor magnet in such a fashion that it has a face-to-face relation with the rotor magnet, andan armature coil laid on the stator yoke, the armature coil having a closed loop structure extending over all of the poles of the rotor magnet and having apexes corresponding in number to 1/2 of the number of poles in the rotor magnet, the apexes being arranged near an outer peripheral surface of the rotor magnet; andat least one cogging generating protrusion, said protrusion protruding upwardly from the stator yoke and being integral with the stator yoke, the cogging generating protrusion being spaced from respective apexes of the armature coil by an angle corresponding to 1/4 of an angular width of one pole in the rotor magnet, the angular width of one pole in the rotor magnet corresponding to a value obtained by dividing 360.degree. by the number of poles in the rotor magnet, said cogging protrusion being positioned on the stator yoke to contact and guide the armature coil to a determined position on the stator yoke.