US3726359A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Muffler for flowing gases
Assignee: IT- ISOLIER- TECHNIK und SCHALLSCHUTA GmbH
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Filing: 1971-04-21
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Granted: 1973-04-10
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Expires: 1991-04-21
Abstract
Abstract A muffler for flowing gases, particularly for ventilation and air conditioning installations, in the form of a tubular duct of preferably rectangular or square cross section, for the reactive and dissipative absorption of sound, having an externally gastight shell which in its interior contains at least one and preferably a plurality of baffles for muffling the sound, said baffles extending substantially in planes parallel to the direction of flow of the gas and consisting of at least one plate of solid material, such as steel sheet, and of at least one layer of a porous material suitable for absorbing sound, the surfaces of the baffles exposed to the flowing has being of abrasionresistant construction, wherein the two external cross sectional regions of a baffle which are exposed to the gas stream each consist of a plate provided with perforated areas disposed in bands, the perforated surface area of the bands being smaller than the remaining unperforated surface area and the two plates being so coordinated that across the direction of gas flow the perforated band-like surface areas of the two plates are relatively staggered.
Inventors
- 👤 R Dierl
- 👤 P Rontgen
- 👤 G Hinners
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:23
CPC Classifications
F; F16; F16L; F16L55/00; F16L55/02; A; A22; A22C; A22C17/00; A22C17/10; F01; F01N; F01N1/00; F01N1/02; F01N1/04; F02; F02C; F02C7/00; F02C7/24; F16L9/00; F16L9/21; F24; F24F; F24F13/00; F24F13/24
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
168 words
A muffler for flowing gases, particularly for ventilations and air conditioning installations in the form of a tubular duct, for the reactive and dissipative absorption of sound, comprising at least one baffle in said tubular duct extending in a plane substantially parallel to the direction of flow of the gas therethrough, said baffle comprising two plates spaced from each other a distance which is a multiple of the thickness of each plate and a layer of porous sound absorbing material between said two plates, each of said plates being provided with perforated areas arranged in bands spaced in the direction of the flow of gas from each other and extending transverse to said direction and separated from each other by band-like areas which are not perforated, the perforated areas of one plate being offset in said direction with respect to those in the other plate, the perforated surface area being smaller than the non-perforated surface area but is at least 15% of the total area of each plate.
Claim 2
Dependent Claim
168 words
A muffler for flowing gases, particularly for ventilations and air conditioning installations in the form of a tubular duct, for the reactive and dissipative absorption of sound, comprising at least one baffle in said tubular duct extending in a plane substantially parallel to the direction of flow of the gas therethrough, said baffle comprising two plates spaced from each other a distance which is a multiple of the thickness of each plate and a layer of porous sound absorbing material between said two plates, each of said plates being provided with perforated areas arranged in bands spaced in the direction of the flow of gas from each other and extending transverse to said direction and separated from each other by band-like areas which are not perforated, the perforated areas of one plate being offset in said direction with respect to those in the other plate, the perforated surface area being smaller than the non-perforated surface area but is at least 15% of the total area of each plate.
Claim 3
Dependent Claim
34 words
A muffler as set forth in claim 1, wherein the outsides of the plates exposed to the gas stream being each provided with a layer of sound absorbing material which has an abrasion-resistant surface.
Claim 4
Dependent Claim
33 words
A muffler as set forth in claim 2, wherein said layer of sound absorbing material comprises mineral wool, and wherein said abrasion resistant surface is in the form of fleece of mineral wool.
Claim 5
Dependent Claim
23 words
A muffler as set forth in claim 1, wherein the width of the perforated band-liKe surface area is between 10 and 100 mm.
Claim 6
Dependent Claim
23 words
A muffler as set forth in claim 1, wherein the perforated band-like surface areas extend substantially perpendicularly to the direction of gas flow.
Claim 7
Dependent Claim
28 words
A muffler as set forth in claim 1, wherein the perforated band-like surface areas extend at an angle of up to 45* to the direction of gas flow.
Claim 8
Dependent Claim
25 words
A muffler as set forth in claim 1, wherein the perforations in the band-like perforated area have the form of a plurality of round holes.
Claim 9
Dependent Claim
25 words
A muffler as set forth in claim 7, wherein the holes have a diameter between 1 and 10 mm, preferably between 3 and 5 mm.
Claim 10
Dependent Claim
26 words
A muffler as set forth in claim 1, wherein the perforations in the region of the band-like surface areas consist of a plurality of polygonal holes.
Claim 11
Dependent Claim
24 words
A muffler as set forth in claim 9, wherein said holes each cover an open cross sectional area of about 1 to 80 sq.mm.
Claim 12
Dependent Claim
24 words
A muffler as set forth in claim 1, wherein the perforations in the region of the perforated bands consist of elongated narrow open slots.
Claim 13
Dependent Claim
26 words
A muffler as set forth in claim 11, wherein the slots are bridged along their length at least once and preferably several times by a web.
Claim 14
Dependent Claim
20 words
A muffler as set forth in claim 11, wherein an acoustically transparent, but abrasion-resistant surface is present behind the slots.
Claim 15
Dependent Claim
46 words
A muffler as set forth in claim 1, wherein the distance between the two plates of a baffle which is exposed to the gas stream on both sides is to about one quarter of the wave length of the sound it is principally desired to muffle.
Claim 16
Dependent Claim
24 words
A muffler as set forth in claim 1, wherein the two plates of the baffles provided with perforated band-like surface areas consist of plastics.
Claim 17
Dependent Claim
24 words
A muffler as set forth in claim 1, wherein the two plates of the baffles provided with perforated band-like surface areas consist of metal.
Claim 18
Dependent Claim
30 words
A muffler as set forth in claim 1, wherein the two plates of the baffles provided with perforated band-like surface areas have a thickness of about 0.5 to 2 mm.
Claim 19
Dependent Claim
36 words
A muffler as set forth in claim 1, wherein the width of the band-like perforated surface areas for muffling primarily the low sound frequencies is about 1/10 of that for muffling primarily the high sound frequencies.
Claim 20
Dependent Claim
23 words
A muffler as set forth in claim 1, wherein the perforated surface area is 15-40 percent of the total area of each plate.
Claim 21
Dependent Claim
23 words
A muffler as set forth in claim 25, wherein the perforated surface area is 20-30 percent of the total area of each plate.
Claim 22
Dependent Claim
32 words
A muffler as set forth in claim 1, wherein the cross section of the perforations in each band of perforations constitutes at least 20 percent of the total area of each band.
Claim 23
Dependent Claim
18 words
A muffler as set forth in claim 1, wherein said layer of sound absorbing material comprises mineral wool.
Claim 24
Dependent Claim
32 words
A muffler as set forth in claim 1, wherein a plurality of said baffles are arranged in said duct spaced in a direction normal to the stream of gases from each other.
Claim 25
Dependent Claim
61 words
A muffler as set forth in claim 23, wherein said duct is of rectangular cross section, and wherein a layer of sound absorbing material is applied to each wall of said duct which extends parallel to said baffles and a plate with spaced band-like perforated surface areas is applied to the surface of said layer facing away from the duct wall.
Claim 26
Dependent Claim
38 words
A muffler as set forth in claim 24, wherein the thickness of the layer between the duct wall and said plate is about one-eighth of the wave length of the sound which is principally desired to be muffled.
References Cited (Backward Citations)
US1974665A
Cited
US2270825A
Cited
US2966954A
Cited
GB907872A
Cited
US3103987A
Cited
FR1391884A
Cited
US3507355A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-09 | 1976-10-09 | 1977-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-09 | 1980-10-09 | 1981-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-09 | 1984-10-09 | 1985-04-10 | $7700.00 | Window Closed / Lapsed |