US20200018204A1 - Anti-resonance muffler - Google Patents
Anti-resonance muffler Download PDFInfo
- Publication number
- US20200018204A1 US20200018204A1 US16/396,031 US201916396031A US2020018204A1 US 20200018204 A1 US20200018204 A1 US 20200018204A1 US 201916396031 A US201916396031 A US 201916396031A US 2020018204 A1 US2020018204 A1 US 2020018204A1
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- United States
- Prior art keywords
- resonance
- port
- exhaust system
- muffler
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N1/00—Silencing apparatus characterised by method of silencing
- F01N1/02—Silencing apparatus characterised by method of silencing by using resonance
- F01N1/023—Helmholtz resonators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N1/00—Silencing apparatus characterised by method of silencing
- F01N1/06—Silencing apparatus characterised by method of silencing by using interference effect
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2470/00—Structure or shape of gas passages, pipes or tubes
- F01N2470/24—Concentric tubes or tubes being concentric to housing, e.g. telescopically assembled
Definitions
- the field of the present disclosure generally relates to vehicle exhaust systems. More particularly, the field of the invention relates to an apparatus and a method for an anti-resonance muffler to attenuate vehicle exhaust system resonance in a narrow frequency range.
- the resonance can be excited at certain engine speeds, thereby amplifying the resonance and causing a potentially objectionable sound or noise.
- Said resonance is also known as drone and is a natural phenomenon of a vehicle exhaust system without some apparatus and method for attenuating or eliminating it.
- a high-flow type of muffler that is commonly used in vehicle exhaust systems is a wide-band attenuation device and has minimal effect on a strong resonance in a lower frequency range.
- a more effective means of attenuating a strong resonance is to employ the use of a Helmholtz resonator.
- a Helmholtz resonator that is tuned to substantially the same frequency as the exhaust system resonance acts to phase-cancel said resonance.
- Some commercially available exhaust systems employ the use of a Helmholtz resonator that is comprised of a chamber and a perpendicularly mounted port tube. Said perpendicularly mounted port tube is a conventional implementation of a Helmholtz resonator and does not maximize the attenuation of vehicle exhaust system resonance. What is needed, therefore, is a device and method for attenuating vehicle exhaust system resonance that maximizes the attenuation effect of a Helmholtz resonator.
- the anti-resonance muffler comprises a chamber having a specific volume, a port having a specific volume, an exhaust tube, an outlet and an inlet which is connected to a vehicle exhaust system.
- the combination of the chamber and port create a Helmholtz resonator that phase-cancels a narrow range of frequencies that are generated by the vehicle exhaust system.
- the chamber and port are mounted radially relative to the exhaust tube.
- the radially mounted Helmholtz resonator port exhibits improved resonance attenuating performance compared to a Helmholtz resonator port that is perpendicularly attached to an exhaust tube.
- FIG. 1A illustrates a cross section view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure.
- FIG. 1B illustrates a perspective cut-away view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure.
- FIG. 2 illustrates a perspective view of a conventional Helmholtz resonator, according to the present disclosure.
- FIG. 3 illustrates frequency response plots of an exemplary embodiment of an anti-resonance muffler as compared to a conventional Helmholtz resonator, according to the present disclosure.
- FIG. 4 illustrates frequency response plots of an exemplary embodiment of an anti-resonance muffler as compared to no muffler, according to the present disclosure.
- the present disclosure describes an apparatus and method for an anti-resonance muffler to reduce vehicle exhaust system resonance.
- the anti-resonance muffler comprises a chamber having a specific volume, a port having a specific volume, an exhaust tube, an outlet and an inlet which is connected to a vehicle exhaust system.
- the combination of the chamber and port create a Helmholtz resonator that phase-cancels a narrow range of frequencies that are generated by the vehicle exhaust system.
- Said chamber and port are mounted radially relative to the exhaust tube.
- FIG. 1A illustrates a cross section view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure.
- the anti-resonance muffler comprises an outer case 5 , comprising a length and a diameter, which creates a chamber 3 , which is mounted radially relative to an exhaust tube 1 , comprising a length and a diameter, and a port tube 2 , comprising a length and a diameter, which is mounted to the outer case 5 .
- the port tube 2 further is mounted radially relative to the exhaust tube 1 and creates a port area 4 between the exhaust tube 1 and the port tube 2 .
- the anti-resonance muffler further comprises an inlet 6 , which comprises a length and two diameters, which is connected to the exhaust system at the smaller diameter end and the port tube 2 at the larger diameter end, and an outlet 7 , which comprises a length and a diameter, which is connected to the exhaust tube 1 at a first end and the exhaust system at a second end.
- FIG. 1B illustrates a perspective cut-away view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure.
- the embodiment comprises components manufactured from 16 gauge stainless steel tube and sheet. Further, the outer case is substantially 12 inches in length and 6 inches in diameter.
- FIGS. 1A and 1B is similar to a Helmholtz resonator which generally comprises a chamber connected to the system of interest through one or more port tubes.
- the Helmholtz resonator generally operates to reflect sound waves back to the source, thereby cancelling out certain frequencies generated by said source.
- the tuning parameters of chamber volume, port area and port length predictably affect the natural frequency of the anti-resonance muffler.
- the anti-resonance muffler effectively attenuates vehicle exhaust system resonance. It will be further appreciated that the anti-resonance muffler exhibits improved attenuation performance compared to that of a conventional Helmholtz resonator which comprises a port tube 8 that is perpendicularly attached to an exhaust tube.
- FIG. 2 illustrates a perspective view of a conventional Helmholtz resonator which comprises a port tube 8 that is perpendicularly attached to an exhaust tube.
- FIG. 3 is a graph 9 illustrating acoustic data acquired during bench testing of the anti-resonance muffler illustrated in FIGS. 1A and 1B .
- the graph 9 illustrates acoustic data acquired during bench testing of a conventional Helmholtz resonator which comprises a port tube 8 that is perpendicularly attached to an exhaust tube.
- Said bench testing consisted of an acoustic source attached to the inlet of each device under test, a studio microphone placed substantially 12 inches from the outlet of each device under test, connected directly to a personal computer, and spectral analysis software operating on said personal computer. Further, all measurement parameters were identical during bench testing of each device under test. Further, the ambient temperature was substantially 72 degrees Fahrenheit during bench testing.
- the anti-resonance muffler was found to be tuned to an attenuation frequency of substantially 80 Hz. Further, using substantially the same tuning parameters as the anti-resonance muffler of chamber volume, port area, port length, the conventional Helmholtz resonator also was found to be tuned to an attenuation frequency of substantially 80 Hz. When the temperature is raised to a target operating temperature of substantially 400 degrees Fahrenheit, the attenuation frequency will rise to substantially 100 Hz.
- an operating temperature must also be taken into account during designing of an anti-resonance muffler.
- an optimal attenuation of sound pressure generally occurs when a natural frequency of the anti-resonance muffler is substantially equal to an excitation frequency of the vehicle exhaust system of interest.
- FIG. 4 is a graph 10 illustrating acoustic data acquired during vehicle testing with the anti-resonance muffler illustrated in FIGS. 1A and 1B . Further, the graph 10 illustrates acoustic data acquired during vehicle testing with no muffler.
- Said vehicle testing consisted of a test vehicle with a 6 cylinder engine, operated at speeds that resulted in an exhaust excitation frequency range of substantially 75 Hz to 200 Hz, and a studio microphone placed substantially in the center of the vehicle cabin connected directly to a portable recorder. Further, acoustic data recordings from said portable recorder were transferred to a personal computer and analyzed using spectral analysis software. Further, all measurement parameters were identical during vehicle testing of the anti-resonance muffler and no muffler. Further, the test vehicle speed was ramped up from a lower speed to a higher speed.
- the graph 9 illustrates a comparison, of relative amplitude (dB) as a function of frequency (Hz), of an anti-resonance muffler and a conventional Helmholtz resonator, based on acoustic data acquired during bench testing. Further, the graph 9 comprises two waveforms. Further, the waveform representing the anti-resonance muffler is depicted by a solid line B and the waveform representing the conventional Helmholtz resonator is depicted by a dashed line A.
- the anti-resonance muffler exhibits improved attenuation, substantially 4 dB on average, over the frequency range of 50 Hz to 250 Hz, as compared to the conventional Helmholtz resonator, with a peak attenuation improvement of substantially 12 dB at 80 Hz.
- the graph 10 illustrates a comparison, of relative amplitude (dB) as a function of frequency (Hz), of an anti-resonance muffler and no muffler, based on acoustic data acquired during vehicle testing. Further, the graph 10 comprises two waveforms. Further, the waveform representing the anti-resonance muffler is depicted by a solid line D and the waveform representing no muffler is depicted by a dashed line C.
- the anti-resonance muffler exhibits effective exhaust system resonance attenuation, substantially 12 dB on average, over the frequency range of 75 Hz to 200 Hz, as compared to no muffler, with a peak attenuation of substantially 20 dB at 105 Hz.
- the anti-resonance muffler effectively attenuates the sound level in the frequency range of interest with a peak attenuation improvement of substantially 12 dB as compared to a conventional Helmholtz resonator which comprises a port tube that is perpendicularly attached to an exhaust tube.
- a conventional Helmholtz resonator which comprises a port tube that is perpendicularly attached to an exhaust tube.
- the anti-resonance muffler effectively attenuates vehicle exhaust system resonance in the frequency range of interest with a peak attenuation of substantially 20 dB as compared to no muffler.
- the anti-resonance muffler may be made of materials that differ from the exemplary embodiment. Further, some embodiments may be constructed to resemble rectangular or oval shapes. Further, some embodiments may be constructed with conical shaped inlets or inlets enclosed within the muffler outer case. It should be understood, therefore, that the anti-resonance muffler may be practiced with a wide variety of shapes, sizes, inlets and materials without deviating from the scope of the present disclosure.
Abstract
An apparatus and method are provided for an anti-resonance muffler to attenuate vehicle exhaust system resonance. The anti-resonance muffler comprises a chamber having a specific volume, a port having a specific volume, an exhaust tube, an outlet and an inlet which is connected to a vehicle exhaust system. The combination of the chamber and port create a Helmholtz resonator device that acts to phase-cancel a narrow range of frequencies that are generated by the vehicle exhaust system. The chamber and port are mounted radially relative to the exhaust tube.
Description
- The field of the present disclosure generally relates to vehicle exhaust systems. More particularly, the field of the invention relates to an apparatus and a method for an anti-resonance muffler to attenuate vehicle exhaust system resonance in a narrow frequency range.
- A vehicle exhaust system that has been designed for minimal back pressure commonly exhibits a substantial resonance. The resonance can be excited at certain engine speeds, thereby amplifying the resonance and causing a potentially objectionable sound or noise. Said resonance is also known as drone and is a natural phenomenon of a vehicle exhaust system without some apparatus and method for attenuating or eliminating it.
- A high-flow type of muffler that is commonly used in vehicle exhaust systems is a wide-band attenuation device and has minimal effect on a strong resonance in a lower frequency range. A more effective means of attenuating a strong resonance is to employ the use of a Helmholtz resonator. A Helmholtz resonator that is tuned to substantially the same frequency as the exhaust system resonance acts to phase-cancel said resonance.
- Some commercially available exhaust systems employ the use of a Helmholtz resonator that is comprised of a chamber and a perpendicularly mounted port tube. Said perpendicularly mounted port tube is a conventional implementation of a Helmholtz resonator and does not maximize the attenuation of vehicle exhaust system resonance. What is needed, therefore, is a device and method for attenuating vehicle exhaust system resonance that maximizes the attenuation effect of a Helmholtz resonator.
- An apparatus and method are provided for an anti-resonance muffler to attenuate vehicle exhaust system resonance. The anti-resonance muffler comprises a chamber having a specific volume, a port having a specific volume, an exhaust tube, an outlet and an inlet which is connected to a vehicle exhaust system. The combination of the chamber and port create a Helmholtz resonator that phase-cancels a narrow range of frequencies that are generated by the vehicle exhaust system. The chamber and port are mounted radially relative to the exhaust tube. The radially mounted Helmholtz resonator port exhibits improved resonance attenuating performance compared to a Helmholtz resonator port that is perpendicularly attached to an exhaust tube.
- The drawings refer to embodiments of the present disclosure in which:
-
FIG. 1A illustrates a cross section view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure. -
FIG. 1B illustrates a perspective cut-away view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure. -
FIG. 2 illustrates a perspective view of a conventional Helmholtz resonator, according to the present disclosure. -
FIG. 3 illustrates frequency response plots of an exemplary embodiment of an anti-resonance muffler as compared to a conventional Helmholtz resonator, according to the present disclosure. -
FIG. 4 illustrates frequency response plots of an exemplary embodiment of an anti-resonance muffler as compared to no muffler, according to the present disclosure. - In general, the present disclosure describes an apparatus and method for an anti-resonance muffler to reduce vehicle exhaust system resonance. The anti-resonance muffler comprises a chamber having a specific volume, a port having a specific volume, an exhaust tube, an outlet and an inlet which is connected to a vehicle exhaust system. The combination of the chamber and port create a Helmholtz resonator that phase-cancels a narrow range of frequencies that are generated by the vehicle exhaust system. Said chamber and port are mounted radially relative to the exhaust tube.
-
FIG. 1A illustrates a cross section view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure. The anti-resonance muffler comprises anouter case 5, comprising a length and a diameter, which creates achamber 3, which is mounted radially relative to anexhaust tube 1, comprising a length and a diameter, and aport tube 2, comprising a length and a diameter, which is mounted to theouter case 5. Theport tube 2 further is mounted radially relative to theexhaust tube 1 and creates aport area 4 between theexhaust tube 1 and theport tube 2. The anti-resonance muffler further comprises aninlet 6, which comprises a length and two diameters, which is connected to the exhaust system at the smaller diameter end and theport tube 2 at the larger diameter end, and anoutlet 7, which comprises a length and a diameter, which is connected to theexhaust tube 1 at a first end and the exhaust system at a second end. -
FIG. 1B illustrates a perspective cut-away view of an exemplary embodiment of an anti-resonance muffler, according to the present disclosure. - In an exemplary embodiment of an anti-resonance muffler, the embodiment comprises components manufactured from 16 gauge stainless steel tube and sheet. Further, the outer case is substantially 12 inches in length and 6 inches in diameter.
- It will be appreciated by those skilled in the art that the exemplary embodiment illustrated in
FIGS. 1A and 1B is similar to a Helmholtz resonator which generally comprises a chamber connected to the system of interest through one or more port tubes. The Helmholtz resonator generally operates to reflect sound waves back to the source, thereby cancelling out certain frequencies generated by said source. It will be further appreciated that the tuning parameters of chamber volume, port area and port length predictably affect the natural frequency of the anti-resonance muffler. - As will be appreciated, the anti-resonance muffler effectively attenuates vehicle exhaust system resonance. It will be further appreciated that the anti-resonance muffler exhibits improved attenuation performance compared to that of a conventional Helmholtz resonator which comprises a
port tube 8 that is perpendicularly attached to an exhaust tube. -
FIG. 2 illustrates a perspective view of a conventional Helmholtz resonator which comprises aport tube 8 that is perpendicularly attached to an exhaust tube. -
FIG. 3 is agraph 9 illustrating acoustic data acquired during bench testing of the anti-resonance muffler illustrated inFIGS. 1A and 1B . Further, thegraph 9 illustrates acoustic data acquired during bench testing of a conventional Helmholtz resonator which comprises aport tube 8 that is perpendicularly attached to an exhaust tube. Said bench testing consisted of an acoustic source attached to the inlet of each device under test, a studio microphone placed substantially 12 inches from the outlet of each device under test, connected directly to a personal computer, and spectral analysis software operating on said personal computer. Further, all measurement parameters were identical during bench testing of each device under test. Further, the ambient temperature was substantially 72 degrees Fahrenheit during bench testing. - During said bench testing, the anti-resonance muffler was found to be tuned to an attenuation frequency of substantially 80 Hz. Further, using substantially the same tuning parameters as the anti-resonance muffler of chamber volume, port area, port length, the conventional Helmholtz resonator also was found to be tuned to an attenuation frequency of substantially 80 Hz. When the temperature is raised to a target operating temperature of substantially 400 degrees Fahrenheit, the attenuation frequency will rise to substantially 100 Hz.
- It will be appreciated, therefore, that in addition to the dimensions and shapes comprising an anti-resonance muffler, an operating temperature must also be taken into account during designing of an anti-resonance muffler. Further, it will be appreciated that an optimal attenuation of sound pressure generally occurs when a natural frequency of the anti-resonance muffler is substantially equal to an excitation frequency of the vehicle exhaust system of interest.
-
FIG. 4 is agraph 10 illustrating acoustic data acquired during vehicle testing with the anti-resonance muffler illustrated inFIGS. 1A and 1B . Further, thegraph 10 illustrates acoustic data acquired during vehicle testing with no muffler. Said vehicle testing consisted of a test vehicle with a 6 cylinder engine, operated at speeds that resulted in an exhaust excitation frequency range of substantially 75 Hz to 200 Hz, and a studio microphone placed substantially in the center of the vehicle cabin connected directly to a portable recorder. Further, acoustic data recordings from said portable recorder were transferred to a personal computer and analyzed using spectral analysis software. Further, all measurement parameters were identical during vehicle testing of the anti-resonance muffler and no muffler. Further, the test vehicle speed was ramped up from a lower speed to a higher speed. - With reference again to
FIG. 3 , thegraph 9 illustrates a comparison, of relative amplitude (dB) as a function of frequency (Hz), of an anti-resonance muffler and a conventional Helmholtz resonator, based on acoustic data acquired during bench testing. Further, thegraph 9 comprises two waveforms. Further, the waveform representing the anti-resonance muffler is depicted by a solid line B and the waveform representing the conventional Helmholtz resonator is depicted by a dashed line A. For the acoustic data shown in thegraph 9, the anti-resonance muffler exhibits improved attenuation, substantially 4 dB on average, over the frequency range of 50 Hz to 250 Hz, as compared to the conventional Helmholtz resonator, with a peak attenuation improvement of substantially 12 dB at 80 Hz. - With reference again to
FIG. 4 , thegraph 10 illustrates a comparison, of relative amplitude (dB) as a function of frequency (Hz), of an anti-resonance muffler and no muffler, based on acoustic data acquired during vehicle testing. Further, thegraph 10 comprises two waveforms. Further, the waveform representing the anti-resonance muffler is depicted by a solid line D and the waveform representing no muffler is depicted by a dashed line C. For the acoustic data shown in thegraph 10, the anti-resonance muffler exhibits effective exhaust system resonance attenuation, substantially 12 dB on average, over the frequency range of 75 Hz to 200 Hz, as compared to no muffler, with a peak attenuation of substantially 20 dB at 105 Hz. - On the basis of the acoustic data illustrated in
FIG. 3 , one skilled in the art will appreciate that the anti-resonance muffler effectively attenuates the sound level in the frequency range of interest with a peak attenuation improvement of substantially 12 dB as compared to a conventional Helmholtz resonator which comprises a port tube that is perpendicularly attached to an exhaust tube. Further, on the basis of the acoustic data illustrated inFIG. 4 , one skilled in the art will appreciate that the anti-resonance muffler effectively attenuates vehicle exhaust system resonance in the frequency range of interest with a peak attenuation of substantially 20 dB as compared to no muffler. - In some embodiments, the anti-resonance muffler may be made of materials that differ from the exemplary embodiment. Further, some embodiments may be constructed to resemble rectangular or oval shapes. Further, some embodiments may be constructed with conical shaped inlets or inlets enclosed within the muffler outer case. It should be understood, therefore, that the anti-resonance muffler may be practiced with a wide variety of shapes, sizes, inlets and materials without deviating from the scope of the present disclosure.
- While the invention has been described in terms of a particular variation, those of ordinary skill in the art will recognize that the invention is not limited to the variation described. To the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the invention found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiment described herein, but only by the scope of the appended claims.
Claims (7)
1. An anti-resonance muffler to attenuate vehicle exhaust system resonance, comprising a chamber with a specific volume, a port with a specific volume, an exhaust tube, an outlet and an inlet which is connected to the vehicle exhaust system of interest.
2. The anti-resonance muffler of claim 1 wherein the chamber and port create a Helmholtz resonator.
3. The anti-resonance muffler of claim 1 wherein the chamber and port are mounted radially relative to the exhaust tube.
4. The anti-resonance muffler of claim 1 wherein the chamber and port are in fluid communication with the vehicle exhaust system of interest.
5. A method for attenuating vehicle exhaust system resonance, comprising:
a chamber and port having suitable volumes for use in an anti-resonance muffler;
an anti-resonance muffler tuned to a suitable frequency to attenuate vehicle exhaust system resonance;
a chamber and port in fluid communication with the vehicle exhaust system of interest;
and a chamber and port mounted radially relative to an exhaust tube.
6. The method of claim 5 , wherein selecting the tuning frequency of the anti-resonance muffler further comprises accounting for effects due to an operating temperature of the vehicle exhaust system of interest.
7. The method of claim 5 , further comprising ensuring an anti-resonance muffler tuned frequency is substantially equal to an excitation frequency of the vehicle exhaust system of interest so as to optimize attenuation of resonance of said exhaust system.
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US16/396,031 US20200018204A1 (en) | 2018-07-16 | 2019-04-26 | Anti-resonance muffler |
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US201862698325P | 2018-07-16 | 2018-07-16 | |
US16/396,031 US20200018204A1 (en) | 2018-07-16 | 2019-04-26 | Anti-resonance muffler |
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US20200018204A1 true US20200018204A1 (en) | 2020-01-16 |
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US16/396,031 Abandoned US20200018204A1 (en) | 2018-07-16 | 2019-04-26 | Anti-resonance muffler |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20210231035A1 (en) * | 2020-01-24 | 2021-07-29 | K&N Engineering, Inc. | Sound attenuating engine exhaust system |
-
2019
- 2019-04-26 US US16/396,031 patent/US20200018204A1/en not_active Abandoned
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US20210231035A1 (en) * | 2020-01-24 | 2021-07-29 | K&N Engineering, Inc. | Sound attenuating engine exhaust system |
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