| 摘要 |
It is an object of the invention to provide an effective technique for making compact power tool having an electric motor (121). A representative power tool may include a tool bit (109), housing (103,105) and an electric motor. The electric motor is housed in the housing and drives the tool bit. The electric motor includes an output shaft (122), a commutator (137), an armature (133), brushes (145), brush holders (143), a brush holder base (141), a cooling fan (151) and a cooling-fan facing surface (141b). The cooling-fan facing surface is formed on the brush holder base. The cooling-fan facing surface faces the cooling fan and extends flat in the centrifugal direction to guide the discharged cooling air from the cooling fan in the centrifugal direction. Because the brush holder base not only secures the brush holder but also smoothly guides the cooling air by means of the cooling-fan facing surface, the size of the electric motor in the axial direction of the output shaft can be reduced. |
