Patent ID: 7898125

Claim:
An electric motor, comprising: a yoke having a cylindrical shape with a bottom; an end bracket blocking an opening of the yoke; an armature core shaft supported so as to be freely rotatable via bearings between a yoke cylinder bottom portion and the end bracket, the yoke cylinder bottom portion being longitudinally mounted, wherein: a plurality of vent holes are formed on the yoke cylinder bottom portion in a direction around the armature core shaft as a shaft core in a scattered manner, all of the plurality of vent holes are formed at the yoke cylinder bottom portion by forming an upper half portion of the vent hole by cutting and stretching out toward an outside of the yoke with respect to a lower half portion so as to bulge out of the yoke cylinder bottom portion and divided at a right-and-left direction dividing line, and the right-and-left direction dividing line has a horizontal shape with right-and-left direction central portions intruding into a side of the upper half portion and an angular shape with right-and-left side portions inclining toward lower end sides.