Sound Attenuating Baffle Including a Non-Eroding Liner Sheet

Abstract

A sound attenuating baffle device used in a duct receiving a gaseous flow in a flow direction therethrough, includes a baffle casing supported within the duct and a fibrous sound absorbing material occupying the hollow interior of the baffle casing. One or more perforated sheet members at least partially defines the exterior of the baffle casing across which the gaseous flow of the duct is arranged to be directed. A liner sheet of a non-eroding, sound absorbing foam material is supported within the hollow interior of the baffle casing against an interior surface of the perforated sheet member(s) so as to span across each of the perforations and prevent direct communication of the fibrous sound absorbing material with the perforations to prevent erosion of the fibrous sound absorbing material into the gaseous flow through the duct.

1 . A sound attenuating baffle device for use in a duct receiving a gaseous flow in a flow direction therethrough, the baffle device comprising:
 a baffle casing having a hollow interior and being adapted to be supported within the duct such that the gaseous flow is directed across an exterior of the baffle casing;   the baffle casing including at least one perforated sheet member having a plurality of perforations therein which at least partially defines the exterior of the baffle casing across which the gaseous flow of the duct is arranged to be directed;   a sound absorbing layer formed of fibrous sound absorbing material occupying the hollow interior of the baffle casing; and   a liner sheet supported within the hollow interior of the baffle casing against an interior surface of said at least one perforated sheet member so as to span across each of the perforations and prevent direct communication of the fibrous sound absorbing material with the perforations;   wherein the liner sheet is formed of a non-eroding, sound absorbing material.   
     
     
         2 . The baffle device according to  claim 1  wherein the liner sheet is formed of a sound absorbing foam material. 
     
     
         3 . The baffle device according to  claim 2  wherein a thickness of the foam material in a direction perpendicular to said at least one perforated sheet is between 0.125 and 2 inches. 
     
     
         4 . The baffle device according to  claim 2  wherein a thickness of the foam material in a direction perpendicular to said at least one perforated sheet which is less than 40% of a thickness of the sound absorbing layer in a direction perpendicular to said at least one perforated sheet. 
     
     
         5 . The baffle device according to  claim 2  wherein the sound absorbing foam material comprises an open-cell foam. 
     
     
         6 . The baffle device according to  claim 2  wherein the sound absorbing foam material comprises a closed-cell foam. 
     
     
         7 . The baffle device according to  claim 2  wherein the sound absorbing foam material comprises a melamine resin. 
     
     
         8 . The baffle device according to  claim 2  wherein the sound absorbing foam material comprises a thermoset polymer. 
     
     
         9 . The baffle device according to  claim 2  wherein the sound absorbing foam material comprises polyethylene. 
     
     
         10 . The baffle device according to  claim 1  wherein the liner sheet fully spans said at least one perforated sheet member. 
     
     
         11 . The baffle device according to  claim 1  wherein the fibrous sound absorbing material is supported within the hollow interior of the baffle casing under resilient compression and wherein the liner sheet is supported against the interior surface of said at least one perforated sheet member by the resilient compression of the fibrous sound absorbing material. 
     
     
         12 . The baffle device according to  claim 1  wherein the baffle casing includes at least one support flange overlapping at least a portion of a perimeter edge of the liner sheet so as to retain the liner against the interior surface of said at least one perforated sheet member. 
     
     
         13 . The baffle device according to  claim 1  wherein the baffle casing comprises two opposed faces having i) a length spanning in a longitudinal direction between a leading end and a trailing end of the baffle casing, ii) a width spanning in a lateral direction between opposing sides of the baffle casing, and iii) a thickness between the two opposed faces which is reduced in dimension relative to the length and the width, the baffle casing being adapted to be supported within the duct such that the longitudinal direction is aligned with the flow direction;
 and wherein said at least one perforated sheet member comprises two perforated sheet members defining the two opposed faces of the baffle casing respectively such that the liner sheet spans the interior surface of each of the two opposed faces of the baffle casing. 
 
     
     
         14 . A sound attenuating baffle device for use in a duct receiving a gaseous flow in a flow direction therethrough, the baffle device comprising:
 a baffle casing having a hollow interior and being adapted to be supported within the duct such that the gaseous flow is directed across an exterior of the baffle casing;   the baffle casing including at least one perforated sheet member having a plurality of perforations therein which at least partially defines the exterior of the baffle casing across which the gaseous flow of the duct is arranged to be directed;   a sound absorbing layer formed of fibrous sound absorbing material occupying the hollow interior of the baffle casing; and   a liner sheet supported within the hollow interior of the baffle casing against an interior surface of said at least one perforated sheet member so as to span across each of the perforations and prevent direct communication of the fibrous sound absorbing material with the perforations;   wherein the liner sheet is a membrane of sound absorbing material.   
     
     
         15 . A sound attenuating baffle device for use in a duct receiving a gaseous flow in a flow direction therethrough, the baffle device comprising:
 a baffle casing having a hollow interior and being adapted to be supported within the duct such that the gaseous flow is directed across an exterior of the baffle casing;   the baffle casing including at least one perforated sheet member having a plurality of perforations therein which at least partially defines the exterior of the baffle casing across which the gaseous flow of the duct is arranged to be directed;   a sound absorbing layer formed of fibrous sound absorbing material occupying the hollow interior of the baffle casing; and   a liner sheet supported within the hollow interior of the baffle casing against an interior surface of said at least one perforated sheet member so as to span across each of the perforations and prevent direct communication of the fibrous sound absorbing material with the perforations;   wherein the liner sheet is formed of a sound absorbing foam material.