| 摘要 |
A suction type road sweeping vehicle utilizes a suction fan for generating a vacuum within an air tight container mounted on the chassis. Suction conduits extend at one end into the container and are provided at the other end with nozzles. A sound attenuation system connected to an outlet duct of the fan comprises an expansion duct inside which is mounted a perforated panel connected to an attenuation duct, whose outlet exhausts to the atmosphere. Air expelled from the fan passes into the expansion duct, through the perforated panel which acts to raise the frequency of the sound of the air and through the attenuated duct, which has a noise absorbing lining which absorbs the sound as the air passes through the duct before being exhausted to atmosphere. Thus, the noise emitted by such road sweepers which, by the very nature of their construction and operation, are noisy vehicles, may be substantially reduced without hindering the flow of discharged air.
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