A DIRECT CURRENT MOTOR HAVING E-SHAPED INTERPOLES AND MAIN POLES WITH UNSYMMETRICAL POLE PIECES

A direct current motor used, for example, in a machine tool, comprising an armature, n main magnetic poles disposed around the armature, each of the main magnetic poles consisting of a pole core on which a field winding is provided and a pole piece extending along the outer circumference of the armature, and n/2 E-shaped interpoles disposed at the intermediate position along the outer circumference of the armature between the adjacent main magnetic poles, and at the central axis of the armature, the angle spanning from the direct axis, which is electrically perpendicular to the interpole axis, to an end portion of a pole piece of a main magnetic pole is unequal to that from the direct axis to the other end portion of the pole piece of the main magnetic pole. Since the number of the E-shaped interpoles is decreased by half, the direct current motor according to the present invention has simple structure and high torque, and the heat generated by the interpoles is relatively decreased.