Coreless and brushless direct-current motor, gifford mcmahon (gm) cryogenic cooler, pulse tube cryogenic cooler, cryopump, magnetic resonance imaging (mri) apparatus, superconducting magnet (scm) apparatus, nuclear magnetic resonance (nmr) apparatus, and cryogenic cooler for cooling semiconductor

Abstract

A coreless and brushless direct-current motor includes an armature coil wound without core and formed in the shape of a saddle; an outside rotor magnet formed by a permanent magnet, the outside rotor magnet being provided at an outside of the armature coil in the shape of a cylinder so as to face the armature coil, the outside rotor magnet being rotated by the magnetic field; an inside rotor magnet formed by a permanent magnet, the inside rotor magnet being provided in the shape of a cylinder at an inside of the armature coil so that the inside rotor magnet has a pole opposite to the outside rotor magnet and a rotational shaft is independently provided; an output shaft connected to the inside rotor magnet; and a sealing part of a barrier structure which sealing part partitions the armature coil and the outside rotor magnet to an outside of the inside rotor magnet and seals the armature coil and the outside rotor magnet.