On the other hand, in the brush motor 1 (with four poles and three slots) of the first example, the number of coils is three, and thus, the blade angle θW increases as illustrated in FIG. 6B. As a result, the area of the blade 13 facing the magnet magnetic pole 5 is secured, and thus, the magnet magnetic flux is easily picked up by the teeth 11, and the magnetic flux is effectively utilized.
FIG. 7A is a view illustrating a brush motor (having no commutating pole) as a comparative example. When a core 10 does not include a commutating pole 14, a flow of a magnetic flux applied from a magnet magnetic pole 5 to a core 10 becomes intermittent, and vibration (cogging) is likely to increase. For example, a magnetic flux indicated by a white arrow in FIG. 7A is not applied to the core 10 in a state where a relatively wide portion of the slit 17 faces the magnet magnetic pole 5. In addition, there is a possibility that an eddy current is generated in a housing 2 to increase a loss. Further, a permeance coefficient decreases, and there is a possibility that demagnetization easily occur.
