| 摘要 |
PURPOSE:To improve heat radiation effect and to reduce radio noise by providing a protrusion integrally with the casing composed of material having high thermal and electrical conductivity and utilizing the protrusion as the heat sink for a power element. CONSTITUTION:A printed board 40 constituting a speed control circuit is supported on a DC motor 5 through a casing body 34 composed of material having high thermal and electrical conductivity. The heat radiating section of a switching element 9 is fixed tightly to a protrusion 41 formed integrally with the casing body 34. Since the casing body 34 is composed of material having high thermal and electrical conductivity, the entirety of the casing body 34 including the protrusion 41 functions as the heat sink for the switching element 9. Furthermore, the casing body 34 shields the electromagnetic noise produced in the printed board 40 because it is composed of material having high electrical conductivity. |
