DC brushless motor having an interior permanent magnet rotor with optimal magnet thickness/air gap relationship

摘要

A DC brushless motor 3 is provided which comprises armature 31 and rotor 32. Rotor 32 is provided with a rotor yoke that has four main poles 321 on its periphery. Slots with a radial-direction size of L.sub. m are formed on main poles 321 of the rotor yoke. Magnetic-field permanent magnet 323 with an approximate thickness of L.sub.m is embedded in each slot 322, such that the radial-direction size L.sub.m of slot 322 and the air gap length L.sub.g of the air gap formed between rotor 32 and armature 31 satisfy the relationship 0 L.sub.m +L.sub.g ≦2 mm.