# US 2008/0185220 A1 · Method of using syntactic foam to reduce noise and machine using same

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- Number: US 2008/0185220 A1
- Document ID: US20080185220A1
- Status: Published application
- Kind: A1
- Application number: 11/985,220
- Filed: 2007-11-14
- Published: 2008-08-07
- Earliest claimed: 2006-11-14
- Assignees: Caterpillar Inc.
- Inventors: Thomas J. Grabenstetter
- Web page: https://patentgrep.com/patent/US20080185220A1

## CPC

- F02B 77/13: Acoustic insulation
- G10K 11/165: Particles in a matrix
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- 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

## Abstract

A method of decreasing engine noise in machines, such as internal combustion engines, by replacing metallic engine components that serve as noise transmission pathways such as oil pans, valve covers, gear covers with similar components made of syntactic foam with a density of at least 0.5 g/cm3 and a hardness at least about equal to that of an equivalent metallic engine part which it is replacing. The syntactic foam is comprised of fluid-filled microballoons in a foam matrix. The microballoons have an outer shell harder than that of the surrounding foam matrix, and a majority of the microballoons are out of contact with one another.

## Claims

### Claim 1

A machine comprising:
a plurality of machine components being attached to one another, and at least one of the components being comprised of syntactic foam;
the syntactic foam including a polymer matrix and a plurality of fluid-filled microballoons, a density of 0.5 g/cm3 or greater, and a hardness of at least about Shore D 74; and
a majority of the microballoons being out of contact with one another, and each microballoon including fluid surrounded by a shell more rigid than the matrix, and the fluid being a majority of a volume of each microballoon.

### Claim 2 (depends on 1)

The machine of claim 1 wherein the machine being an engine, and the at least one component includes a valve cover.

### Claim 3 (depends on 1)

The machine of claim 1 wherein the at least one component includes a gear cover.

### Claim 4 (depends on 1)

The machine of claim 1 wherein the at least one component includes an oil pan.

### Claim 5

An engine comprising:
a plurality of engine components being attached to one another and including a portion being metallic components and a portion being comprised of a syntactic foam component.

### Claim 6 (depends on 5)

The engine of claim 5 wherein the syntactic foam component includes a valve cover.

### Claim 7 (depends on 5)

The engine of claim 5 wherein the syntactic foam component includes a gear cover.

### Claim 8 (depends on 5)

The engine of claim 5 wherein the syntactic foam component includes an oil pan.

### Claim 9 (depends on 5)

The engine of claim 5 wherein the syntactic foam includes a density of 0.5 g/cm3 or greater.

### Claim 10 (depends on 5)

The engine of claim 5 wherein the syntactic foam includes a hardness of at least about Shore D 74.

### Claim 11 (depends on 5)

The engine of claim 5 wherein the syntactic foam includes a polymer matrix and a plurality of fluid-filled microballoons, and a majority of the microballoons being out of contact with one another.

### Claim 12 (depends on 5)

The engine of claim 5 wherein the syntactic foam includes a polymer matrix and a plurality of fluid-filled microballoons, and each microballoon includes a fluid surrounded by a shell more rigid than the matrix and the fluid being a majority of a volume of each microballoon.

### Claim 13 (depends on 12)

The engine of claim 12 wherein the syntactic foam components include at least one of a valve cover, a gear cover, and an oil pan; and
the syntactic foam includes a density of 0.5 g/cm3 or greater, a hardness of at least about Shore D 74, and a majority of the microballoons being out of contact with one another.

### Claim 14

A method of reducing sound emitted from a machine comprising a step of:
substituting a syntactic foam machine component for a metallic machine component.

### Claim 15 (depends on 14)

The method of claim 14 wherein the machine being an engine, and the machine component including at least one of a valve cover, a gear cover, and an oil pan.

### Claim 16 (depends on 14)

The method of claim 14 wherein the syntactic foam component includes a polymer matrix and a plurality of fluid-filled microballoons, a density of 0.5 g/cm3 or greater, and a hardness of at least about Shore D 74; and
a majority of the microballoons being out of contact with one another, and each microballoon including fluid surrounded by a shell more rigid than the matrix, and the fluid being a majority of a volume of each microballoon.