# US 12,222,128 B2 · Sound absorbing duct for environmental control system

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- Number: US 12,222,128 B2
- Document ID: US12222128B2
- Status: Granted
- Kind: B2
- Application number: 18/346,447
- Filed: 2023-07-03
- Published: 2023-11-09
- Granted: 2025-02-11
- Earliest claimed: 2018-08-20
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Bryce A. Vandyke; John Erik West; Douglas D. Maben; Andrew K. Fung; David R. C. Cannal
- Web page: https://patentgrep.com/patent/US12222128B2

## CPC

- B32B 5/18: characterised by features of a layer {of} foamed material
- F24F 13/0263: {Insulation for air ducts}
- B32B 1/08: Tubular products
- B32B 3/08: characterised by added members at particular parts {(layer formed of separate pieces of material which are juxtaposed side-by-side B32B3/14, B32B3/18)}
- B32B 3/12: characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
- B32B 3/266: {characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12}
- B32B 5/022: {Non-woven fabric}
- B32B 5/024: {Woven fabric}
- B32B 5/245: {another layer next to it being a foam layer}
- B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)}
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 27/065: {of foam}
- B32B 27/08: of synthetic resin
- B32B 27/12: next to a fibrous or filamentary layer
- B32B 27/286: {comprising polysulphones; polysulfides}
- B32B 27/288: {comprising polyketones}
- B32B 27/304: {comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF}
- B32B 2250/20: All layers being fibrous or filamentary
- B32B 2266/0285: Condensation resins of aldehydes, e.g. with phenols, ureas, melamines
- B32B 2266/06: Open cell foam
- B32B 2307/102: Insulating
- B32B 2307/304: Insulating
- B32B 2307/3065: Flame resistant or retardant, fire resistant or retardant
- B32B 2307/718: Weight, e.g. weight per square meter
- B32B 2307/724: Permeability to gases, adsorption
- B32B 2307/7242: Non-permeable
- B32B 2597/00: Tubular articles, e.g. hoses, pipes
- B32B 2605/18: Aircraft
- B64D 2013/0603: {Environmental Control Systems}
- F24F 13/0245: {Manufacturing or assembly of air ducts; Methods therefor}
- F24F 13/0281: {Multilayer duct}
- F24F 2013/242: {Sound-absorbing material}
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT

## Abstract

A duct includes a rigid air-permeable tube of composite material. The duct also includes a layer of insulation coupled to an exterior surface of the rigid air-permeable tube. The duct further includes a non-rigid insulation layer in contact with the layer of insulation. The non-rigid insulation layer forms an air-impermeable duct wall.

## Claims

### Claim 1

A duct comprising:
a rigid tube of composite material;
an insulation layer disposed within the rigid tube; and
a biasing member disposed within the rigid tube, the biasing member configured to restrain the insulation layer against an interior surface of the rigid tube, wherein the insulation layer is coupled to the biasing member by the biasing member being threaded through the insulation layer.

### Claim 2 (depends on 1)

The duct of claim 1, wherein the biasing member comprises a spring, and wherein the insulation layer comprises open cell foam or aramid felt.

### Claim 3 (depends on 1)

The duct of claim 1, further comprising an adhesive material coupled to coupling the insulation layer to the rigid tube of composite material and configured to restrain the insulation layer, wherein the adhesive material includes adhesive tape, and wherein the adhesive tape includes metallized polyether ether ketone (MPEEK).

### Claim 4 (depends on 1)

The duct of claim 1, further comprising a sleeve coupled to an exterior surface of the rigid tube via an adhesive material, the sleeve configured to overlap a portion of an end of the rigid tube and to overlap a portion of an end of a second duct to couple the duct and the second duct in fluid communication.

### Claim 5 (depends on 1)

The duct of claim 1, further comprising an internal coupler coupled to an interior surface of the rigid tube, the internal coupler configured to overlap a portion of an end of the rigid tube and to overlap a portion of an end of a second duct to couple the duct and the second duct in fluid communication.

### Claim 6 (depends on 1)

A vehicle including the duct of claim 1, the vehicle comprising:
an environmental control system, the environmental control system including:
an air conditioning unit;
first zone ducts;
second zone ducts; and
riser ducts coupled to the first zone ducts and the second zone ducts, wherein one of the first zone ducts, the second zone ducts, or the riser ducts comprises the duct of claim 1.

### Claim 7 (depends on 6)

The vehicle of claim 6, wherein the first zone ducts do not include a noise attenuating muffler.

### Claim 8

A method of manufacturing a duct, the method comprising:
inserting insulation into a rigid tube of composite material to form a layer of insulation within the rigid tube, the layer of insulation in contact with an inner surface of the rigid tube; and
inserting a biasing member into the rigid tube of composite material to secure the layer of insulation within the rigid tube, wherein the layer of insulation is coupled to the biasing member by the biasing member being threaded through the layer of insulation.

### Claim 9 (depends on 8)

The method of claim 8, further comprising, prior to inserting the insulation, coupling the insulation to the biasing member, and wherein the insulation and the biasing member are inserted into the rigid tube as a unitary piece.

### Claim 10 (depends on 8)

The method of claim 8, wherein the insulation, the biasing member, or both are inserted into the rigid tube via an inlet of the rigid tube, an outlet of the rigid tube, or both.

### Claim 11 (depends on 1)

The duct of claim 1, wherein the composite material of the rigid tube is non-permeable and forms an air impermeable exterior duct wall.

### Claim 12 (depends on 1)

The duct of claim 1, wherein the biasing member is a helical compression spring.

### Claim 13 (depends on 1)

The duct of claim 1, wherein the insulation layer comprises open cell foam, aramid felt, or high mass fabric, and combinations thereof.

### Claim 14 (depends on 1)

The duct of claim 1, wherein the insulation layer comprises open cell foam, and said open cell foam is melamine foam.

### Claim 15 (depends on 1)

The duct of claim 1, wherein the insulation layer comprises aramid felt, and said aramid felt is aramid fibers, para-aramid fibers, or a combination thereof.

### Claim 16 (depends on 15)

The duct of claim 15, wherein the insulation layer comprises aramid fibers, selected from meta-aramid fibers, para-aramid fibers, or a combination thereof; and wherein said aramid fibers are matted, condensed, and/or pressed together.

### Claim 17 (depends on 16)

The duct of claim 16, wherein the insulation layer comprises meta-aramid fibers.

### Claim 18 (depends on 8)

The method of claim 8, wherein the composite material of the rigid tube is non-permeable and forms an air impermeable exterior duct wall.

### Claim 19 (depends on 8)

The method of claim 8, wherein the biasing member is a helical compression spring.

### Claim 20 (depends on 8)

The method of claim 8, wherein the layer of insulation comprises open cell foam, aramid felt, or high mass fabric, and combinations thereof.

### Claim 21 (depends on 8)

The method of claim 8, wherein the layer of insulation comprises open cell foam, and said open cell foam is melamine foam.

### Claim 22 (depends on 8)

The method of claim 8, wherein the layer of insulation comprises aramid felt, and said aramid felt is aramid fibers, para-aramid fibers, or a combination thereof.

### Claim 23 (depends on 22)

The method of claim 22, wherein the layer of insulation comprises aramid fibers, selected from meta-aramid fibers, para-aramid fibers, or a combination thereof; and wherein said aramid fibers are matted, condensed, and/or pressed together.

### Claim 24 (depends on 23)

The method of claim 23, wherein the layer of insulation comprises meta-aramid fibers.