Patent ID: 8471431
Filing Date: 2013-06-25
Classification: H02K

Abstract:
1. A motor comprising: at least one magnet forming four or more magnetic pole portions; an armature including a rotation shaft, an armature core fixed to the rotation shaft and having a plurality of teeth, a coil wound around the teeth, and a commutator fixed to the rotation shaft and having a plurality of segments arranged in a circumferential direction of the rotation shaft; and a common brush, a low-speed drive brush, and a high-speed drive brush spaced apart and arranged along the circumferential direction of the rotation shaft to slidably contact the commutator, with each brush having a width in the circumferential direction of the rotation shaft; wherein the number of the teeth is the same as the number of segments; when the number of the magnetic pole portions formed by the magnet is represented by P and the number of the teeth is represented by S, (2S/P) is an odd number; the width and location of each brush in the circumferential direction of the rotation shaft are set so that the three types of the brushes, which are the common brush, the low-speed drive brush, and the high-speed drive brush, all do not simultaneously short-circuit two of the segments that are adjacent to each other in the circumferential direction; and each of the three types of the brushes has a timing at which the brush starts to short-circuit the two of the segments, and the timings of the three types of the brushes differ from each other.