Motor rotor assembly and method of aligning pole center of permanent magnet thereof

A motor rotor assembly comprising:

• a permanent magnet including a plurality of disc type magnet units which have center holes and are segmented in an axial direction;
• a first shaft and a second shaft coupled to both end portions of the permanent magnet;
• a rod which protrudes from a center of the first shaft in the axial direction, is coupled to a center of the second shaft, and passes through the center hole of each of the plurality of disc type magnet units to assemble the permanent magnet, the rod including a reference guide at a portion of the rod on which at least one disc type magnet unit among the plurality of disc type magnet units is fixed and the remaining disc type magnet units rotatable on the remaining portions of the rod;
• and
• a sleeve which surrounds an outer circumferential surface of the permanent magnet and fixes the permanent magnet to the first and second shafts,
• wherein, when the plurality of disc type magnet units are assembled, the plurality of disc type magnet units are formed to have a small amount of magnetic force relative to a preset maximum magnetic force, such that pole centers of the disc type magnet units adjacent to each other are aligned to each other due to an attractive force and a repulsive force therebetween, and
• after the assembly, the plurality of disc type magnet units are fully magnetized to have the preset maximum magnetic force, such that polarities of the disc type magnet units, which are adjacent to each other, are formed to be the same.