Conventional brushed rotatory devices suffer the disadvantages of excessive noise due to the interaction between the brushes and the commutator. In addition, the debris generated by wear and tear of the brushes due to the interaction between the brushes and the commutator may also deposit in or migrate to undesired areas to cause such problems as contamination and short circuit. Conventional brushed rotatory devices often use impellers or fans to dissipate the heat generated during the operations of the rotatory devices via forced convection. The use of impellers or fans may nonetheless exacerbate the issues of having debris in undesired areas because the forced convection caused by the air flow from the impellers or fans may carry or cause such debris to migrate to such undesired areas.
For example, FIG. 7 illustrates a schematic diagram of the air flow paths in a conventional brushed motor. The brushed motor includes a stator 1, a rotor 2, and an impeller or fan 3. The brushed motor further includes an end cap 4 that also covers or houses the impeller or fan 3. The impeller or fan 3 intakes air from the bottom of the brushed motor through the area near the rotor 2 and the magnet 5 and generates air flow that may carry or cause debris from spent brushes due to commutation between the commutator 6 and brushes (not shown in FIG. 7) to migrate to undesired areas such as the area in which electronic components 7 are located. The deposit of the debris in such an area near the electronic components 7 may cause short circuits due to the electrical conductivity of the debris. In addition, the debris may be inadvertently vented to the atmosphere via, for example, one or more openings 8 in a part of the brushed motor.
Therefore, there exists a need for an improved rotatory device that may reduce the noise level during operation. There also exists a need for an improved rotatory device that may reduce or eliminate the possibility of having debris generated by the interaction between brushes and the commutator contaminating undesired areas.