Magnetic bearing, drive device equipped with the same, and pump

A drive device comprising:

• a rotor,
• a magnetic bearing supporting the rotor by magnetic force, and
• a drive mechanism rotatably driving the rotor, wherein the magnetic bearing includes:
• a bearing rotor member made of a magnetic material disposed in the rotor;
• and
• a bearing stator member arranged around the bearing rotor member, wherein
• the bearing stator member includes a core made of a magnetic material and a coil wound around the core, and
• a longitudinal cross-sectional shape of the core has:
• a first part extending in a first direction orthogonal to a direction opposed to the bearing rotor member, and wound around with the coil;
• a pair of second parts extending from both end portions in the first direction of the first part toward the bearing rotor member side and subsequently extending in a direction approaching each other in the first direction;
• and
• a pair of third parts extending from respective distal end portions of the pair of second parts toward the bearing rotor member side, wherein
• the bearing rotor member includes a permanent magnet supplying a bias magnetic flux to a magnetic circuit formed by the bearing rotor member and the core, and
• a length in the first direction of the coil wound around the first part is greater than a distance between opposed surfaces in the first direction of the pair of third parts.

A pump comprising:

• a rotor;
• a magnetic bearing supporting the rotor by magnetic force;
• a drive mechanism rotatably driving the rotor;
• and
• a pump mechanism that includes an impeller attached to the rotor, wherein the magnetic bearing includes:
• a bearing rotor member made of a magnetic material disposed in the rotor;
• and
• a bearing stator member arranged around the bearing rotor member, wherein
• the bearing stator member includes a core made of a magnetic material and a coil wound around the core,
• a longitudinal cross-sectional shape of the core has:
• a first part extending in a first direction orthogonal to a direction opposed to the bearing rotor member, and wound around with the coil;
• a pair of second parts extending from both end portions in the first direction of the first part toward the bearing rotor member side and subsequently extending in a direction approaching each other in the first direction;
• and
• a pair of third parts extending from respective distal end portions of the pair of second parts toward the bearing rotor member side, wherein
• the bearing rotor member includes a permanent magnet supplying a bias magnetic flux to a magnetic circuit formed by the bearing rotor member and the core, and
• a length in the first direction of the coil wound around the first part is greater than a distance between opposed surfaces in the first direction of the pair of third parts.