| 摘要 |
PURPOSE:To make a layer of air reduce the blowing sound from a radial-flow type blower and achieve a lowering of the noise of operation by mounting a sound-absorbing material with the help of a guide rib projected in such a manner as to form a layer of air in a specified space bounded in part by an inner wall of a casing. CONSTITUTION:Radial-flow type blowers 25 set inside an outer body 15 are used in a pair, consisting of one functioning as an air-supplying blower 36 which is placed in an air-supplying passageway 23 and creates a flow of air to be supplied and the other functioning as an air-discharging blower 35 which is placed in an air-discharging passageway 24 and creates a flow of air to be discharged. Layers of air in void spaces 31 formed inside a casing 26 have a noise-attenuating effect on the blowing sound of a current of air from the air-supplying blower 34 or the air-discharging blower 35 in action and make a sound-absorbing material 30 more effective especially in the sound-absorbing characteristics in the low frequency region than where the casing 26 is lined directly with the sound-absorbing material 30, thus contributing to the reduction of the noise. A guide rib 29 formed in the casing 26 makes it easier to attach the sound-absorbing material 30 in place, helps to prevent the sound-absorbing characteristics from degradation that would occur from irregularities in shape of the passageway for air, and improves the casing 26 in mechanical strength. |
