| 摘要 |
A switch and a motor-cooling device for an electric fan comprise a motor, a housing, a controller and a knob. The housing is defined with a concave portion in an end thereof, and on the bottom of the concave portion are provided plural assembling portions. The concave portion is formed with an outward-enlarged arc-shaped guiding surface around a periphery thereof and interiorly defined with plural inlet holes. The controller and the knob are assembled to the assembling portions. The knob is exteriorly provided with a tapered arc-shaped guiding surface. With the guiding surface of the housing and the guiding surface of the knob, the air within the angular scope of the concave portion and behind the knob can be completely sucked into the concave portion, thus increasing the amount of the air sucked into the housing and obtaining the optimal heat dissipation efficiency.
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