Armature and electric motor having the same

An armature comprising:

• a shaft;
• a core that is installed to the shaft and includes a plurality of teeth, which are arranged one after another in a circumferential direction of the core at generally equal angular intervals and define a plurality of slots;
• an insulator that is installed to the core, wherein the insulator includes a plurality of winding guide portions, which are received in the plurality of slots, respectively, and each of the plurality of winding guide portions has a winding guide wall;
• and
• a plurality of windings, each of which is wound in the core through corresponding two of the plurality of slots, wherein:
• each of the plurality of windings is electrically insulated from the core by the winding guide wall of a corresponding one of the plurality of winding guide portions in each of the corresponding two of the plurality of slots;
• and
• the winding guide wall of at least one of the plurality of winding guide portions is configured differently from the winding guide wall of each of the rest of the plurality of winding guide portions and includes a radial bottom wall section, which is radially outwardly spaced from a radial bottom wall section of the corresponding one of the plurality of slots by a predetermined distance and contacts a corresponding one of the plurality of windings.