| 摘要 |
PROBLEM TO BE SOLVED: To uniformalize sound pressure distribution and to reduce the generation of humming sound by a method wherein generating noise at a tongue part is brought into a reverse phase in a spot right below a filter air outlet surface. SOLUTION: A fan filter until comprises a chamber 1 having a filter 12 to purify air; a turbo fan 5 having the even number of blades 4 arranged at equal pitches nipped between a main plate 2 and a side plate 3 in the chamber; and a motor 6 for driving the turbo fan 5. Further, the fan filter unit comprises a scroll casing 9 having a tongue part 8 and an air outlet 7 in two directions, arranged rotationally symmetrically in a 180 deg. arc; and a shield plate 10 provided approximately at a central part with an opening part 10a and this constitution brings generating noise (NZ noise) into a reverse phase at a tongue part in a spot at right below a filter air outlet surface, uniformalizes sound pressure distribution, and provides a fan filter unit to reduce the generation of humming sound. |
