US3700069A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wave interference silencer
Assignee: Motors Liquidation Co
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Filing: 1971-05-20
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Granted: 1972-10-24
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Expires: 1991-05-20
Abstract
Abstract A wave interference silencer includes a pair of coaxially disposed pipes which are separated by helical baffle and define an axial flow path through the inner pipe and an outer helical flow path between the pipes and the baffle. A plurality of inwardly projecting longitudinal ribs are formed on the outer pipe to radially space the baffle from the outer pipe and define a plurality of frequency independent annular acoustical and fluid leakage paths between adjacent turns of helical flow paths. The leakage paths provide parallel acoustical couplings which are effective upon increasing frequency to attenuate acoustical energy in the helical flow path thereby producing a reduced acoustical pressure at the exit end of the silencer such as the portion of the acoustical energy from the inner pipe reversely flows through the leakage paths for additional attenuation.
Inventors
- 👤 John T Rausch
- 👤 William J Parker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:19
CPC Classifications
F; F01; F01N; F01N1/00; F01N1/06
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
112 words
A wave interference attenuating device, comprising: means defining first and second flow paths having frequency dependent acoustical reactances, said second flow path having an inlet and an outlet acoustically coupled in parallel with the first flow path, said flow paths having conduits differing in acoustical lengths for placing sound waves traveling therethrough in phase opposition at said outlet; acoustical fluid leakage means between spaced sections of said second flow path having a frequency independent acoustical resistance, said leakage means providing parallel acoustical couplings between said spaced sections for attenuating the sound waves flowing through the second flow path without an appreciable phase shift thereby producing a reduced acoustical pressure at said outlet.
Claim 2
Dependent Claim
112 words
A wave interference attenuating device, comprising: means defining first and second flow paths having frequency dependent acoustical reactances, said second flow path having an inlet and an outlet acoustically coupled in parallel with the first flow path, said flow paths having conduits differing in acoustical lengths for placing sound waves traveling therethrough in phase opposition at said outlet; acoustical fluid leakage means between spaced sections of said second flow path having a frequency independent acoustical resistance, said leakage means providing parallel acoustical couplings between said spaced sections for attenuating the sound waves flowing through the second flow path without an appreciable phase shift thereby producing a reduced acoustical pressure at said outlet.
Claim 3
Dependent Claim
158 words
In a wave interference attenuating device having a pair of conduits acoustically coupled in parallel between an inlet and an outlet, one of the conduits including baffle means haVing multiple turns which defines a helical flow path and establishes differing acoustical lengths between the conduits so as to place the sound waves traveling through the conduits in phase opposition at the outlet wherein said helical flow path has a substantially frequency dependent reactance, the improvement comprising: acoustical and fluid leakage paths in the baffle means acoustically connecting successive turns of said helical flow path to provide parallel acoustical couplings, said leakage paths having frequency independent acoustical resistances whereby said leakage paths are effective upon increasing frequency to attenuate acoustical energy flowing through said helical flow path thereby producing a reduced acoustical pressure at said outlet such that a portion of the acoustical energy from the other of said conduits flows reversely through said leakage paths for additional attenuation.
Claim 4
Dependent Claim
158 words
In a wave interference attenuating device having a pair of conduits acoustically coupled in parallel between an inlet and an outlet, one of the conduits including baffle means haVing multiple turns which defines a helical flow path and establishes differing acoustical lengths between the conduits so as to place the sound waves traveling through the conduits in phase opposition at the outlet wherein said helical flow path has a substantially frequency dependent reactance, the improvement comprising: acoustical and fluid leakage paths in the baffle means acoustically connecting successive turns of said helical flow path to provide parallel acoustical couplings, said leakage paths having frequency independent acoustical resistances whereby said leakage paths are effective upon increasing frequency to attenuate acoustical energy flowing through said helical flow path thereby producing a reduced acoustical pressure at said outlet such that a portion of the acoustical energy from the other of said conduits flows reversely through said leakage paths for additional attenuation.
Claim 5
Dependent Claim
162 words
A broad band wave interference device comprising: a cylindrical inner pipe; a cylindrical outer pipe concentrically disposed with respect to said inner pipe; a helical baffle between said pipes, said baffle being connected to one of said pipes and having a clearance with respect to the other of said pipes, said pipes forming an inner axial flow path through inner pipe and an outer helical flow path between said pipes and said baffle, said helical flow path having an acoustical reactance substantially dependent on frequency; inlet means and outlet means fluidly and acoustically coupling said flow paths in parallel; connecting means structurally connecting said other of said pipes to said baffle and forming annular acoustical leakage passages between spaced sections of said helical flow path, said passages having an acoustical resistance substantially independent of frequency and being effective upon increasing sound wave frequencies for attenuating sound waves flowing through said helical flow path thereby producing reduced acoustical pressure at said outlet means.
Claim 6
Dependent Claim
162 words
A broad band wave interference device comprising: a cylindrical inner pipe; a cylindrical outer pipe concentrically disposed with respect to said inner pipe; a helical baffle between said pipes, said baffle being connected to one of said pipes and having a clearance with respect to the other of said pipes, said pipes forming an inner axial flow path through inner pipe and an outer helical flow path between said pipes and said baffle, said helical flow path having an acoustical reactance substantially dependent on frequency; inlet means and outlet means fluidly and acoustically coupling said flow paths in parallel; connecting means structurally connecting said other of said pipes to said baffle and forming annular acoustical leakage passages between spaced sections of said helical flow path, said passages having an acoustical resistance substantially independent of frequency and being effective upon increasing sound wave frequencies for attenuating sound waves flowing through said helical flow path thereby producing reduced acoustical pressure at said outlet means.
Claim 7
Dependent Claim
175 words
A broad band wave interference device comprising: a cylindrical inner pipe having an axial flow path; a cylindrical outer pipe concentrically disposed with respect to said inner pipe; a multiple turn helical baffle between said pipes, said baffle being connected to said inner pipe and having a diametral clearance with respect to said outer pipes, said pipes and said baffle forming outer flow paths having multiple turns and a substantially frequency dependent acoustical reactance; an inlet and an outlet fluidly and acoustically coupling said flow paths in parallel; a plurality of longitudinally extending inwardly projecting ribs formed on the outer pipe, said ribs engaging said baffle and forming annular acoustical leakage passages between adjacent turns of said outer flow path, said passages having a substantially frequency independent acoustical resistance and being effective upon increasing frequency to attenuating sound waves flowing through said outer flow path thereby producing reduced acoustical pressure at said outlet such that a portion of the acoustical energy from the axial flow path flows upstream through said leakage paths for additional attenuation.
Claim 8
Dependent Claim
175 words
A broad band wave interference device comprising: a cylindrical inner pipe having an axial flow path; a cylindrical outer pipe concentrically disposed with respect to said inner pipe; a multiple turn helical baffle between said pipes, said baffle being connected to said inner pipe and having a diametral clearance with respect to said outer pipes, said pipes and said baffle forming outer flow paths having multiple turns and a substantially frequency dependent acoustical reactance; an inlet and an outlet fluidly and acoustically coupling said flow paths in parallel; a plurality of longitudinally extending inwardly projecting ribs formed on the outer pipe, said ribs engaging said baffle and forming annular acoustical leakage passages between adjacent turns of said outer flow path, said passages having a substantially frequency independent acoustical resistance and being effective upon increasing frequency to attenuating sound waves flowing through said outer flow path thereby producing reduced acoustical pressure at said outlet such that a portion of the acoustical energy from the axial flow path flows upstream through said leakage paths for additional attenuation.
Claim 9
Dependent Claim
170 words
A broad band wave interference silencer comprising: a cylindrical inner pipe; a helical baffle connected to the inner pipe; a cylindrical outer pipe concentrically disposed with respect to said inner pipe and connected to said baffle, said pipes forming an inner axial flow path through inner pipe and an outer helical flow path between said pipes and said baffle, said helical flow path having an acoustical reactance substantially dependent on frequency; inlet means and outlet means fluidly and acoustically coupling said flow paths in parallel; acoustical and fluid leakage apertures formed in said baffle establishing acoustical couplings between spaced sections of said helical flow path having an acoustical resistance substantially independent of frequency, said apertures being effective upon increasing sound wave frequencies for attenuatinG sound waves flowing through said helical flow path thereby producing reduced acoustical pressure at said outlet means and a pressure imbalance between said flow paths whereby a portion of the acoustical energy from the axial flow path is conducted upstream through said apertures for additional attenuation.
Claim 10
Dependent Claim
170 words
A broad band wave interference silencer comprising: a cylindrical inner pipe; a helical baffle connected to the inner pipe; a cylindrical outer pipe concentrically disposed with respect to said inner pipe and connected to said baffle, said pipes forming an inner axial flow path through inner pipe and an outer helical flow path between said pipes and said baffle, said helical flow path having an acoustical reactance substantially dependent on frequency; inlet means and outlet means fluidly and acoustically coupling said flow paths in parallel; acoustical and fluid leakage apertures formed in said baffle establishing acoustical couplings between spaced sections of said helical flow path having an acoustical resistance substantially independent of frequency, said apertures being effective upon increasing sound wave frequencies for attenuatinG sound waves flowing through said helical flow path thereby producing reduced acoustical pressure at said outlet means and a pressure imbalance between said flow paths whereby a portion of the acoustical energy from the axial flow path is conducted upstream through said apertures for additional attenuation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |