Electromagnetic rotary machinery

An electromagnetic rotary machinery comprising:

• a rotor;
• and
• a stator disposed across a gap from the rotor, wherein
• the electromagnetic rotary machinery is configured to generate a bearing force that causes the rotor to levitate without contact, by an electromagnetic force or a magnetic force,
• at least one of the rotor and the stator includes a plurality of teeth formed of a plurality of tiers of iron cores around which a winding is wound, and
• permeance of at least one of the gap and the iron cores in a magnetic circuit that goes around the stator and the rotor along a radial direction and a circumferential direction decreases in one direction from one end side to another end side in an axial direction by changing at least one of:
• a circumferential width of a tooth tip of each of the teeth;
• a circumferential width of a tooth body;
• a radial width of a back yoke disposed on an outer peripheral side of the tooth body:
• a circumferential width or a radial length of a groove in the tooth tip;
• and
• permeability of the teeth, where the permeance is an amount that represents ease of flowing of magnetic flux.