| 摘要 |
PURPOSE:To decrease the noises radiated from the above carrier which is superposed and joined with metallic flat foil and metallic corrugated foil and is inserted into a metallic outside cylinder and to decrease the uncomfortable noises of high frequencies by constituting the above-mentioned outside cylinder of double layers of metallic plates in contact with each other and specifying the thickness of the outside cylinder to a specific thickness or above. CONSTITUTION:The above-mentioned carrier 1 which is superposed and joined with the metallic flat foil 3 and the metallic corrugated foil 4 is inserted into the metallic outside cylinder 6. This outside cylinder 6 is constituted of the double layers of the metallic plates 7, 8 in contact with each other and the thickness of the outside cylinder 6 is specified to >=1.6mm in total. Namely, the outside cylinder 6 is formed as thick as >=1.6mm in total and, therefore, the transmission sounds are drastically attenuated at the time of passing the outside cylinder 6. In addition, the outside cylinder 6 is made into the plural layers, by which the natural frequencies of the outside cylinder are lowered and the frequencies of the resonance sounds are lowered. Consequently, the noises radiated from the metal carrier are decreased and the uncomfortable noises of the high frequencies are decreased as well. |
