AIR CONDITIONING DUCT

摘要

PURPOSE:To provide an air conditioning duct having a high sound attenuation rate by a method wherein an inner pipe having a hollow pipe made of viscous resilient material is present in an inner pipe constituted by a hollow pipe of rigid material through an air layer. CONSTITUTION:An inner pipe 1 constituted by a hollow pipe made of viscous resilient material is placed at an outer pipe 2 comprised of a hollow pipe of rigid material through an air layer of a thickness of about 9.5mm. The outer pipe 2 is comprised of acrylic resin formed product having a thickness of about 2mm and an inner diameter of about 50mm. The inner pipe 1 forms a thickness of about 0.5mm and an inner diameter of about 30mm. It is comprised of silicone rubber having a resiliency of about 5.0X10<5>N/m<3> and a density of 1000kg/m<3>. Operation of the inner pipe is performed such that noise generated or transmitted in an air conditioning duct passes through the inner pipe 1 made of viscous resilient material and a pipe wall of the inner pipe 1 is vibrated in a radial direction and then a sound wave near a resonant frequency can be rapidly attenuated by a hysteresis loss of the pipe wall caused by the pipe wall.