| 摘要 |
PURPOSE:To provide a ventilating fan capable of reducing noise sound generated by a blower while restricting an increment of aeration resistance. CONSTITUTION:A blower 6 having an aeration casing 5 having a fan suction port 4 adjacent to a main body suction port 3 of a ceiling surface 2 is installed within a main body 1 having the main body suction port 3 at its lower surface. A sound-proof device 9 having an inner aeration passage 10 with a larger aeration area than that of the fan suction port 4 and formed with a plurality of air layers 14 directed in a crossing direction in respect to a direction of a rotary shaft 13 of the blower 6 from the inner aeration passage 10 is disposed within a space between the fan suction port 4 within the main body 1 and the main body suction port 3. Since there is scarcely aeration resistance even if air passes through the sound-proof device 9, there is no opportunity to reduce an efficiency of ventilation and noise entered into a plurality of air layers vigorously repeats its reflection and sound absorption and then sound is efficiently reduced. |
