# US 9,378,721 B2 · Low frequency acoustic attenuator and process for making same

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- Number: US 9,378,721 B2
- Document ID: US9378721B2
- Status: Granted
- Kind: B2
- Application number: 14/534,804
- Filed: 2014-11-06
- Published: 2015-05-07
- Granted: 2016-06-28
- Earliest claimed: 2013-11-06
- Assignees: ZIN Technologies
- Applicants: Zin Technologies, Inc.
- Inventors: Bart F. Zalewski; William B. Dial
- Web page: https://patentgrep.com/patent/US9378721B2

## CPC

- G10K 11/172: using resonance effects
- B29K 2101/12: Thermoplastic materials
- B29L 2031/00: Other particular articles
- B33Y 10/00: Processes of additive manufacturing
- B33Y 80/00: Products made by additive manufacturing
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING

## Abstract

A method of manufacturing an acoustic attenuation device includes three-dimensionally printing a pair of sheets and webs that cooperate with the sheets to define attenuation chambers. Each chamber has at least one opening through which excited air resonates.

## Claims

### Claim 1

A method of manufacturing an acoustic attenuation device, the method comprising:
Three-dimensionally printing a pair of sheets and webs that cooperate with the sheets to define broadband sound attenuation chambers, each chamber having at least one opening through which excited air resonates, further comprising three-dimensionally printing a partition along the length of at least one chamber to divide the at least one chamber into a pair of chamber portions, each partition including an inner wall and an outer wall spaced from the inner wall by an annular space.

### Claim 2 (depends on 1)

The method recited in claim 1 wherein the annular space between the outer wall and the inner wall is empty.

### Claim 3 (depends on 1)

The method recited in claim 1 further comprising three-dimensionally printing mesh extending over at least one opening for damping the excited air through the opening.

### Claim 4 (depends on 1)

The method recited in claim 1 further comprising three-dimensionally printing a neck outside the chambers in fluid communication with at least one opening for varying an acoustic frequency of the chamber.

### Claim 5 (depends on 1)

The method recited in claim 1 further comprising three-dimensionally printing a partition along a longitudinal length of at least one chamber to divide the chamber into a pair of chamber portions for damping the excited air.

### Claim 6 (depends on 5)

The method recited in claim 5 wherein the chamber portions have different lengths.

### Claim 7 (depends on 5)

The method recited in claim 5 wherein the at least one opening comprises a pair of openings, each opening associated with one of the pair of chamber portions.

### Claim 8 (depends on 5)

The method recited in claim 5 wherein each partition includes an inner wall, an outer wall, and a powdered material between the inner wall and the outer wall.

### Claim 9 (depends on 5)

The method recited in claim 5, wherein the partition includes damping fibers that dissipate energy to provide resistance to the passage of the excited air through the partition.

### Claim 10 (depends on 1)

The method recited in claim 1, wherein multiple chambers are interconnected through an opening in a web between two or more adjacent chambers.

### Claim 11 (depends on 1)

The method recited in claim 1 further comprising three-dimensionally printing a partition along the length of each chamber to divide each chamber into a pair of chamber portions, each partition having a position along the length of the respective chamber different from each other partition.

### Claim 12 (depends on 11)

The method recited in claim 11 wherein each partition includes an inner wall, an outer wall, and a powdered material between the inner wall and the outer wall.

### Claim 13 (depends on 1)

The method recited in claim 1 wherein the chambers are centered about a common axis and concentric with one another.

### Claim 14

A method of manufacturing an acoustic attenuation device, the method comprising:
three-dimensionally printing a pair of sheets and webs that cooperate with the sheets to define attenuation chambers, each chamber having at least one opening through which excited air resonates, wherein the chambers include a plurality of first chambers in a first plane and a plurality of second chambers arranged in a second plane that is perpendicular to the first plane.

### Claim 15 (depends on 1)

The method recited in claim 1 wherein the step of three-dimensionally printing the pair of sheets and the webs comprises extrusion deposition.

### Claim 16 (depends on 1)

The method recited in claim 1 further comprising three-dimensionally printing a first panel into the sheets to close a first end of each chamber and three-dimensionally printing a second panel into the sheets to close a second end of each chamber.

### Claim 17

An acoustic attenuation device extending from a first end to a second end comprising:
first and second sheets;
a plurality of webs positioned between the first and second sheets and cooperating with the first and second sheets to form a series of sound attenuation chambers containing a volume and mass of air;
a partition positioned along the length of at least one chamber to divide the at least one chamber into a pair of chamber portions, each partition including an inner wall and an outer wall spaced from the inner wall by an annular space;
a first panel secured to the sheets and closing the chambers at the first end of the device;
a second panel secured to the sheets and closing the chambers at the second end of the device; and
an opening through which excited air resonates in fluid communication with each chamber.

### Claim 18 (depends on 17)

The acoustic attenuation device of claim 17 wherein the chamber partition has a cross section for damping the excited air, a powdered material being positioned in the annular space between the inner wall and outer wall.

### Claim 19 (depends on 17)

The acoustic attenuation device of claim 17 wherein at least one opening is covered by mesh for damping the excited air through the opening.

### Claim 20 (depends on 17)

The acoustic attenuation device of claim 17 wherein a cross-section of the partition includes damping fibers that dissipate energy to provide resistance to the passage of the excited air through the partition.

### Claim 21 (depends on 17)

The acoustic attenuation device of claim 17 wherein the chambers comprise a plurality of first chambers in a first plane and at least one second chamber in a second plane different from the first plane.

### Claim 22 (depends on 17)

The acoustic attenuation device of claim 17 wherein the chambers include a plurality of first chambers in a first plane and a plurality of second chambers arranged in a second plane perpendicular to the first plane.

### Claim 23 (depends on 17)

The acoustic attenuation device of claim 17 wherein the annular space between the outer wall and the inner wall is empty.