Flexible muffler for use in aircraft environmental control systems and method of manufacture
View Patent ↗A flexible muffler for use in an aircraft environmental system includes a flexible body having a porous inner layer and an air impervious outer layer both supported by a helically wound adhesively attached reinforcing cord. The flexible body includes a pair of connecting end caps at opposed ends thereof which are joined to the flexible body in an air tight attachment. The resulting muffler provides acoustic energy absorptive and is readily flexed and bent to accommodate space restrictions within the environmental control system of the aircraft.
1. For use in an aircraft environmental control system, a flexible muffler comprising:
a pair of duct connectors;
an inner sleeve formed into a cylinder having a single length-wise seam and defining a first outer surface and formed of a sound pervious material having opposed ends joined to said duct connectors and defining a muffler passage therethrough;
a first helix of reinforcing cord wound solely upon and adhesively joined adhesively to said first outer surface of said inner sleeve;
a layer of acoustic absorptive material upon said inner sleeve and said first helix of reinforcing cord;
an outer sleeve formed into a cylinder having a single length-wise seam and defining a second outer surface and formed of an air impervious material having opposed ends joined to said duct connectors and forming a seal therewith; and
a second helix of reinforcing cord wound solely upon and adhesively joined solely to said second outer surface outer sleeve,
said inner and outer sleeves and said first and second helixes of reinforcing cord cooperating to maintain said muffler passage in an open state when said flexible muffler is flexed or bent.
2. The flexible muffler set forth in claim 1 wherein said outer sleeve is formed of a sheet of electrostatically etched fluoropolymer shaped to a generally cylindrical shape having said overlapping longitudinal seam joined by adhesive bonding.
3. The flexible muffler set forth in claim 2 wherein said inner sleeve is formed of an air pervious material.
4. The flexible muffler set forth in claim 3 wherein said inner sleeve is formed of a woven material.
5. The flexible muffler set forth in claim 4 wherein said outer sleeve is formed of FEP TEFLON.
6. The flexible muffler set forth in claim 5 wherein said first and second helixes of reinforcing cord are formed of polymer cord.
7. The flexible muffler set forth in claim 6 wherein said polymer cord is formed of a self-reinforcing thermoplastic polymer.
8. The flexible muffler set forth in claim 7 wherein said acoustic absorptive material includes a melamine foam.