Direct current motor

Abstract

A direct-current motor comprises: 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 and connected with the first and second carbon brushes and first and second ends of the exciting coil, respectively, to control a direction of a current supplied to the exciting coil; and a cover disposed at the end of the shell to enclose the brush holder. The motor is compact in structure, small in volume, and occupies a small mounting space, and the work load of sealing and insulating is reduced, thus reducing the cost and improving the manufacture efficiency.

What is claimed is: 
     
         1 . A direct-current 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 and connected with the first and second carbon brushes and first and second ends of the exciting coil, respectively, to control a direction of a current supplied to the exciting coil; and   a cover disposed at the end of the shell to enclose the brush holder.   
     
     
         2 . The direct-current motor as set forth in  claim 1 , wherein the motor is a “series excited” motor such that the motor defines a series arrangement of an armature and exciter windings. 
     
     
         3 . The direct-current motor as set forth in  claim 2 , wherein the current-direction controller includes first and second contactors each of which has a pair of normally open contacts, a pair of normally closed contacts, and a contactor coil,
 when the contactor coil of the first contactor is energized and the contactor coil of the second contactor is de-energized, the pair of normally open contacts of the first contactor close, the pair of normally dosed contacts thereof open, and the 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 de-energized, the pair of normally open contacts of the second contactor close, the pair of normally closed contacts thereof open, and the motor rotates in a second direction substantially opposite to the first direction.   
     
     
         4 . The direct-current motor as set forth in  claim 3 , 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, and
 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.   
     
     
         5 . The direct-current motor as set forth in  claim 4 , wherein each of the first and second carbon brushes includes two sub-carbon brushes, the two sub-carbon brushes of the first carbon brush are disposed substantially opposite to each other in a substantially radial direction on the brush holder, and the two sub-carbon brushes of the second carbon brush are disposed substantially opposite to each other in the radial direction on the brush holder. 
     
     
         6 . The direct-current motor as set forth in  claim 4 , wherein each of the other ends of the contactor coils of the first and second contactors is adapted to connect with an external control switch.