Air induction housing having a perforated wall and interfacing sound attenuation chamber
An air induction housing having a perforated wall which provides a first intake noise attenuation modality and further having a sound attenuation chamber interfaced with the perforated wall which provides a second intake noise attenuation modality. Multiply apertured tubes of the sound attenuation chamber provide a Helmholtz resonator, wherein the tubes are superposed the wall perforations so that, attendant to the noise attenuation, ample air entry into the air induction housing is provided. The size, number and arrangement of the perforations is selected such that ample airflow is provided and audibility of intake noise is minimized in conjunction with the corresponding tubes of the sound attenuation chamber.
1. An air induction housing providing sound attenuation of engine intake noise, comprising:
a housing having a predetermined configuration;
a perforated wall, wherein a plurality of perforations are formed in said perforated wall, said plurality of perforations collectively providing a predetermined intake opening size for said housing, said housing further comprising an engine air intake connection; and
a sound attenuation chamber connected with said perforated wall and said housing, wherein said sound attenuation chamber comprises a plurality of selectively apertured tubes passing through an internal space of said sound attenuation chamber, wherein each tube is disposed superposed a respective perforation of said perforated wall, wherein each tube is free of layering externally therearound, and wherein the internal space is free of absorbent filling material such that the internal space is filled only with air;
wherein said plurality of perforations have a distribution selected in relation to said configuration such that the engine intake noise is first attenuated at said plurality of perforations; and wherein the engine intake noise is secondly attenuated at said sound attenuation chamber.
2. The air induction housing of claim 1 , wherein said sound attenuation chamber further comprises:
each tube having a sidewall defining a central opening superposed its respective perforation, wherein each sidewall of each tube has a selected number of apertures formed therein; and
an internal space having thereinside air which is sealed except for said apertures.
3. The air intake housing of claim 2 , wherein each perforation of said plurality of perforations has a minimum area in which sound created by a predetermined maximum airflow rate therethrough is below a predetermined level; and wherein said maximum airflow rate has a Mach number through said plurality of perforations less than substantially 0.125.
4. The air intake housing of claim 3 , wherein said sound attenuation chamber further comprises baffling disposed within said internal space.
5. The air intake housing of claim 3 , wherein a number, n, of said perforations ranges substantially between 10,000 and 5; and wherein each said perforation has an average diameter of substantially between 1 and 50 millimeters.
6. The air induction housing of claim 5 , wherein said number, n, ranges substantially between 420 and 10.
7. The air intake housing of claim 5 , wherein said distribution provides a maximum spacing between adjacent perforations limited by said predetermined configuration.
8. The air intake housing of claim 7 , wherein said number, n, ranges substantially between 420 and 10.
9. The air intake housing of claim 8 , wherein said sound attenuation chamber further comprises baffling disposed within said internal space.
10. A method for optimizing engine intake noise attenuation at an air induction housing, comprising the steps of:
determining an engine airflow rate requirement;
determining an inlet area responsive to the determined airflow rate requirement;
selecting a perforation area for each perforation of a selected plurality of perforations of a perforated wall wherein the area and number of the perforations is selected responsive to said step of determining an inlet area;
determining a first configuration of an air induction housing, the configuration including the perforated wall;
selecting a distribution of the perforations; and
determining a second configuration of a sound attenuation chamber, wherein a plurality of apertured tubes thereof are disposed such that each tube is superposed a respective perforation;
wherein the distribution and the first configuration provide a selected first attenuation of the intake noise at the perforations; and
wherein the distribution and the second configuration provide a selected second attenuation of the intake noise at the sound attenuation chamber.
11. The method of claim 10 , wherein said step of determining the second configuration comprises:
selecting each tube to have a sidewall defining a central opening superposed its respective perforation, wherein each sidewall of each tube has a selected number of apertures formed therein; and
selecting an internal space having thereinside air which is sealed except for said apertures.
12. The method of claim 11 , wherein said step of determining the second configuration further comprises selecting the tubes, the apertures of the tubes and the internal space of the sound attenuation chamber to collectively provide selectively optimal Helmholtz resonations of the intake noise passing through the tubes with respect to the air within the internal space.
13. The method of claim 12 , wherein said step of determining the second configuration further comprises selecting baffling disposed within said internal space to thereby further optimize the Helmholtz resonations.
14. The method of claim 11 , wherein said step of selecting a distribution comprises providing a maximum spacing between adjacent perforations, said maximum spacing being limited by said step of determining the configuration; and wherein said step of selecting a perforation area comprises maximizing acoustic wave destructive interference adjacent said plurality of perforations.
15. The method of claim 14 , wherein said step of selecting a perforation area further comprises selecting a minimum perforation area in which sound created by the airflow therethrough responsive to the determined engine airflow rate requirement is below a predetermined level; wherein said step of selecting a perforation diameter further comprises selecting a perforation area such that a Mach number of the airflow rate through the perforations is less than substantially 0.125.
16. The method of claim 11 , wherein said step of determining the second configuration further comprises selecting the tubes, the apertures of the tubes and the internal space of the sound attenuation chamber to collectively provide selectively optimal Helmholtz resonations of the intake noise passing through the tubes with respect to the air within the internal space.
17. The method of claim 16 , wherein said step of determining the second configuration further comprises selecting baffling disposed within said internal space to thereby further optimize the Helmholtz resonations.
18. The method of claim 11 , wherein said step of selecting a perforation area comprises selecting a minimum perforation area in which sound created by the airflow therethrough responsive to the determined engine airflow rate requirement is below a predetermined level; wherein said step of selecting a perforation diameter further comprises selecting a perforation area such that a Mach number of the airflow rate through the perforations is less than substantially 0.125.
19. An air induction housing made according to the method of claim 18 .
20. An air induction housing made according to the method of claim 17 .