A commutator motor generally comprises a stator having a plurality of stator poles and a rotor having a rotor shaft, a rotor core fixed to the shaft, a commutator fixed to the shaft and a rotor windings wound about poles of the rotor core and electrically connected to segments of the commutator. Brushes transfer electrical power to the windings via the commutator. The number of brushes generally increases with an increase in the number of the stator poles. For example, a two pole motor usually has two brushes, and a four pole motor usually has four brushes. The increase in the number of brushes increases the cost as well as the size of the motor.
As is known, wave winding is one methods to reduce the number of brushes. However, traditional wave windings require the motor to have a rotor with an odd number of winding slots and a commutator with an odd number of segments, and also require the number of the winding slots (rotor poles) as well as the number of segments to be not a multiple of the number of stator poles. Therefore, wave windings are limited to some specific motors. Further more, traditional wave windings are wound by a winding machine using a single flyer due to the odd number of coils, which takes more time than using a dual flyer winding machine.
It is desired to develop an improved multi-pole motor, particularly a motor which has an even number of segments.