Heat insulating noise reducing duct

Abstract

A heat insulating noise reducing duct includes: an internal layer formed by helically winding a flat fibrous band and integrally bonding outer circumferential faces of adjacent joint parts of the band by resin reinforcing bands to thereby form a substantially smooth cylindrical shape; one or more resin linear bodies helically wound between these adjoining resin reinforcing bands and bonded to the fibrous band; an open-cell foam layer formed by helically winding an open-cell foam resin band onto an outer circumferential face of the inner layer while making its paired side edges abut each other; an intermediate sheet layer formed by helically winding a thin resin sheet-like band onto an outer circumferential face of the open-cell foam band while partially overlapping the resin sheet-like band, and by integrally bonding the overlapped parts; a closed-cell foam layer formed by helically winding a closed-cell foam resin band onto an outer circumferential face of the sheet layer while making its paired side edges abut each other; and an external layer formed by helically winding a thin resin sheet-like band onto an outer circumferential face of the closed-cell foam layer while partially overlapping the resin sheet-like band and by integrally bonding the overlapped parts. The fibrous band, the resin reinforcing band, the resin linear body, the open-cell foam resin band, the resin band forming the intermediate sheet layer, the closed-cell foam resin band, and the resin band forming the external layer are wound at an identical helical pitch.