| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a means which forcedly radiates a quantity of heat generated in coils. <P>SOLUTION: Radiating layers 381 with high thermal conductivity are formed on an upper face of a circuit board 38. Each coil 37 and each radiating layer 381 are confronted in an axial direction, and a heat conductive material 39 intervenes at a gap formed by each coil 37 and each radiating layer 381. The outline of the circuit board 38 is projected outward in a radial direction more than an outside diameter of an impeller cup 20. Heat generated in the coils 37 is transmitted to the radiating layers 381 through the heat conductive materials 39. A radiating surface becomes wider as the heat is transferred to the radiating layers 381, and the heat is naturally radiated to fresh air. Moreover, as the outline of the circuit board 38 is projected outward in the radial direction more than the outside diameter of the impeller cup 20, airflow generated by rotation of an impeller 2 is directed onto vicinity of an outer periphery of the circuit board 38, and the heat transmitted to the radiating layers 381 is forcedly radiated. <P>COPYRIGHT: (C)2007,JPO&INPIT |
