Patent ID: 8519647

Claim:
An armature-and-exciter-windings series DC motor comprising: a stator including a shell, a main magnetic pole, and an exciting coil; a rotator disposed inside the stator; a brush holder disposed at an end of the shell; first and second carbon brushes disposed on the brush holder and contacted with the rotator respectively; a current direction controller disposed on the brush holder, connected with the first and second carbon brushes and first and second ends of the exciting coil respectively so as to control a direction of a current supplied to the exciting coil, and including first and second contractors, each of which has a pair of normally open contacts, a pair of normally closed contacts, and a contactor coil; and a cover disposed at the end of the shell so as to enclose the brush holder, wherein, when the contactor coil of the first contactor is energized and the contactor coil of the second contractor is deenergized, the pair of normally open contacts of the first contactor close, the pair of normally closed contacts thereof open, and the DC motor rotates in a first direction and, when the contactor coil of the second contactor is energized and the contactor coil of the first contactor is deenergized, the pair of normally open contacts of the second contactor close, the pair of normally closed contacts thereof open, and the DC motor rotates in a second direction opposite to the first direction; wherein one normally open contact of the first contactor is connected with one normally closed contact thereof and the first end of the exciting coil respectively and one normally open contact of the second contactor is connected with one normally closed contact thereof and the second end of the exciting coil respectively; wherein the other normally closed, contact of the first contactor is connected with the first carbon brush and the other normally closed contact of the second contactor respectively and the other normally open contact of the second contactor is connected with the second carbon brush, the other normally open contact of the first contactor, and an end of the contactor coil of each of the first and second contactors respectively; wherein each of the first and second carbon brushes comprises two sub-carbon brushes; wherein the two sub-carbon brushes of the first carbon brush are disposed opposite to each other in a radial direction on the brush holder; wherein the two sub-carbon brushes of the second carbon brush are disposed opposite to each other in the radial direction on the brush holder; wherein the two sub-carbon brushes of the first carbon brush are connected to each other in series and the two sub-carbon brushes of the second carbon brush are connected with the shell respectively; and wherein a first line connecting the two sub-carbon brushes of the first carbon brush is substantially perpendicular to a second line connecting the two sub-carbon brushes of the second carbon brush.