Abstract: A columnar solid body rotor for DC dynamo electric machines in which a cylindrical dust core, obtained by solidifying a finely powdered magnetic material with an insulating material such as a synthetic resin or the like is mounted on the rotor shaft and a closely wound winding is disposed on the outer periphery of the dust core. The volume-conversion permeability of the rotor is selected several times higher than the space permeability, thereby to increase the effective flux of the rotor.

Abstract: A direct current dynamo electric machine comprising a non-magnetic cylindrical rotor wherein a small-diameter sleeve-like insulating cylinder is secured to a rotor shaft, a winding is disposed around the outer periphery of said insulating cylinder and most of the volume of the rotor is occupied by the winding, a mechanism for rotatably supporting the rotor, and a stator having permanent magnets for equalizing the leakage flux of the field of permanent magnets by means of a reverse magnetic field, a large magnetic field being applied to the non-magnetic cylindrical rotor.

Abstract: A permanently magnetic stator for a DC dynamo electric machine which is adapted to define an extremely large air gap between pole pieces disposed face to face with a non-magnetic or substantially non-magnetic columnar solid body rotor. Two main permanent magnets, rectangular in cross section, are disposed opposite to each other on the inside of a square-shaped stator yoke to set up a double-pole magnetic field in the air gap. The pole pieces are plate-like and respectively mounted on the opposed surfaces of the main magnets so that the magnetic field along the center line of the air gap defined between the pole pieces is parallel to leakage magnetic fields formed on both sides of the extremely large air gap between the main magnets.