ACOUSTIC ABSORPTION DUCT STRUCTURAL BODY

摘要

PROBLEM TO BE SOLVED: To provide an excellent acoustic absorption characteristic in all frequency areas by specifying length in the duct direction of an extended duct part in a structural body consisting of an air cleaner and a duct part connected to it and forming an inner tube having an opening part by a skewer shaped projected thing to an acoustic absorption material. SOLUTION: An acoustic absorption duct part 2 is set on the side of an air suction port partitioned by an air filter 5. At this time, an acoustic absorption material 6 is pressurized by the skewer shaped projected thing 7 and devised not to be blown off by a current 8 of an air current. Such an acoustic absorption duct structural body forms a portion (extended duct) an inside diameter of which is extended in a 1.5-4 times rangein a 5-200cm range in the duct direction and in length of a range of 1-90% of 1/4 wavelength of sound of 50HzE169 in a duct (base duct). The acoustic absorption material 6 is constituted of a fiber aggregate, and this fiber aggregate uses a thing an average fiber diameter of which is in a range of 1-50μm and surface density of which is in a range of 50-2000g/m<2> .