| 摘要 |
A centrifugal fan driven by an electronic-commutation d.c. motor is provided with a housing (1) which defines a volute (2), an impeller (4) which is coupled for rotation with the motor shaft (7) being mounted within the fan housing. The motor is placed within a protective casing (13) which also contains at least one printed-circuit board (23) for supporting the motor control circuit (26), the casing being adjacent to the external face (36) of a closure disk (9) of the fan housing (1). The fan motor casing (13) has an annular extension (14) corresponding to the fan housing (1) and the printed-circuit board (23) is housed within said extension and placed in substantially parallel relation to the fan-housing closure disk (9) in sufficiently close proximity to said disk to be subjected primarily by thermal conduction to the cooling action produced by the fan impeller (4). |
