Electric motor

An electric motor comprising:

• a yoke having a cylindrical section about an axial direction;
• two pairs of permanent magnets fixed to an inner circumferential surface of the cylindrical section and arranged such that magnetic N poles and S poles are alternately disposed in a circumferential direction;
• an armature rotatably supported about the axial direction further inside in a radial direction than the permanent magnets;
• and
• an armature core constituted by a plurality of core plates, which are stacked, each having a core main body fitted and fixed onto the rotary shaft and ten teeth protruding from the core main body outward in the radial direction, and on which a winding is wound between two of the teeth neighboring the circumferential direction,
• wherein the cylindrical section has first flat sections and transition sections, each of the transition sections being configured to connect two of the first flat sections in the circumferential direction,
• the permanent magnets are disposed at positions corresponding to the transition sections, respectively, in the circumferential direction,
• wherein the teeth comprise two tooth groups, each constituted by five deformed teeth neighboring the circumferential direction,
• the two tooth groups are disposed to be point-symmetrical to each other about the rotary shaft,
• the five deformed teeth are constituted by:
• a first-type deformed tooth formed extending from the core main body and substantially inclined toward an opposite side of the winding direction of the winding with respect to a virtual standard tooth extending along the radial direction;
• and
• four second-type deformed teeth formed in the circumferential direction at the winding direction side of the first-type deformed tooth, the four second-type deformed teeth each extending from the core main body and substantially inclined in the winding direction with respect to a virtual standard tooth extending along the radial direction,
• a first-type deformed slot is formed between the second-type deformed teeth and the first-type deformed tooth of the other tooth group adjacent to the second-type deformed teeth at the winding direction side of the second-type deformed teeth,
• a second-type deformed slot is formed between the first-type deformed tooth and one of the second-type deformed teeth closest to the first-type deformed tooth at the winding direction side of the first-type deformed tooth, and
• three third-type deformed slots are formed between the second deformed teeth neighboring each other in the circumferential direction, and
• the first deformed slot, the second deformed slot, and the third deformed slots are sequentially formed in the winding direction.