ANTI-RESONANCE MUFFLER
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.
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.
BRIEF SUMMARY OF THE INVENTIONAn 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:
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.
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
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.
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.
With reference again to
With reference again to
On the basis of the acoustic data illustrated in
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
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.
Type: Application
Filed: Apr 26, 2019
Publication Date: Jan 16, 2020
Inventor: Eric Brockway (Fenton, MI)
Application Number: 16/396,031