Abstract: A direct current motor having interpoles mounted therein. The motor comprises a circular-shaped yoke, two main magnetic poles equidistantly disposed inside of the yoke and with their polarities different from each other, an armature, having armature windings wound thereon, which is actuated by an electromotive force caused by the main magnetic poles and which is rotated in the magnetic field generated by the main magnetic poles, and interpoles which are disposed at positions located between the two main magnetic poles so as to face the armature windings. Each of the interpoles comprises three small poles which are disposed inside of the yoke and are magnetically insulated from the yoke. As a result of this construction magnetic circuits are formed between the adjacent two small poles of each interpole and the armature.

Abstract: Disclosed is a direct current motor which comprises an armature, provided with armature windings thereon, and a plurality of field magnet devices, each of the field magnet devices being divided into three parts along the rotational direction of the armature. The parts are a main pole, which consists of a permanent magnet or an electromagnet activated by field windings wound thereon and which is disposed at a central portion of the field magnet device, and a pair of auxiliary poles, each of which consists of a permanent magnet. One of the auxiliary poles is disposed at one end of the main pole and the other auxiliary pole is disposed at the other end of the main pole. The permeability of the auxiliary poles is selected to be smaller than that of the main pole, and the polarity of the auxiliary poles is selected to be the same as that of the main pole.

Abstract: A drive circuit for a DC motor provided with an armature having an armature winding and a plurality of field poles. The field poles are each composed of a main pole excited by a field winding and an auxiliary pole formed with a permanent magnet of the same polarity as the main pole. An armature current is shunted to supply a field current to the field winding connected in series to the armature. The field current remains zero until the armature current reaches a predetermined value, and increases with an increase in the armature current after the latter exceeds the predetermined value. As a result of this, in the region in which the armature current is small, that is, in the high-speed region of the motor, a torque larger than that of a DC series motor is obtained, and in the region in which the armature current is large, that is, in the low-speed region of the motor, a torque larger than that of a permanent magnet type DC motor is provided.