Patent Grant
7712577
The present invention relates to air induction housings used in the automotive arts for air intake and air filtration for supplying intake air to an internal combustion engine. More particularly, the present invention relates to an air induction housing having a perforated wall for simultaneously providing air intake and sound (acoustic) attenuation.
Internal combustion engines rely upon an ample source of clean air for proper combustion therewithin of the oxygen in the air mixed with a supplied fuel. In this regard, an air induction housing is provided which is connected with the intake manifold of the engine, wherein the air induction housing has at least one air induction opening for the drawing-in of air, and further has a filter disposed thereinside such that the drawn-in air must pass therethrough and thereby be cleaned prior to exiting the air induction housing on its way to the intake manifold.
Problematically, a consequence of the combustion of the fuel-air mixture within the internal combustion engine is the generation of noise (i.e., unwanted sound). A component of this noise is intake noise which travels through the intake manifold, into the air induction housing, and then radiates out from the at least one air induction opening. The intake noise varies in amplitude across a wide frequency spectrum dependent upon the operational characteristics of the internal combustion engine, and to the extent that it is audible to passengers of the motor vehicle, it is undesirable.
As shown at
One end of the snorkel 14 is connected to the induction duct 20 adjacent the air intake opening 22. The other end of the snorkel 14 is connected to the resonator 12, which is essentially an enclosed chamber. Each end of the snorkel 14 is open so that intake noise may travel between the induction duct 20 and the resonator 12. The resonator 12 is shaped and the snorkel 14 configured (as for example as two snorkel tubes 14a, 14b) such that the intake noise passing through the induction duct toward the air intake opening in part passes into the resonator and then back into the induction duct so as to attenuate the intake noise by frequency interference such that the audibility of the intake noise exiting the air intake opening is minimized.
While the prior art solution to provide attenuation of intake noise does work, it does so by requiring the inclusion of an externally disposed snorkel and resonator combination which adds expense, installation complexity and packaging volume accommodation.
Accordingly, what is needed is to somehow provide attenuation of intake noise as an inherent feature of the air induction housing so as to thereby minimize expense, complexity and packaging volume.
The present invention is an air induction housing having a perforated wall which simultaneously provides ample air entry into the air induction housing and excellent intake noise attenuation, while attendantly minimizing expense and complexity of fabrication and assembly, as well as packaging volume.
The air induction housing having a perforated sound attenuation wall according to the present invention includes an air induction housing having an internally disposed filtration media, and is preferably characterized by mutually selectively sealable and separable housing components; an intake manifold duct interfaced therewith adapted for connection to the intake manifold of an internal combustion engine; and a perforated sound attenuation wall integrated with the air induction housing and characterized by a plurality of perforations formed of the air induction housing, itself. The air induction housing may be of any configuration and is suitably shaped to suit a particular motor vehicle application.
The size, number and arrangement of the perforations is selected, per the configuration of the air induction housing and the airflow requirements of the internal combustion engine, such that a multi-faceted synergy is achieved whereby: 1) ample airflow is provided through the perforations to supply the internal combustion engine with required aspiration over a predetermined range of engine operation, and 2) audibility of intake noise is minimized. The multi-faceted synergy is based upon simultaneous optimization of three facets: 1) providing a plurality of perforations which collectively have an area that accommodates all anticipated airflow (aspiration) requirements of a selected internal combustion engine; 2) minimizing the diameter while simultaneously adjusting the area of the perforations such that the airflow demand of the internal combustion engine involves an airflow speed through each perforation that is below a predetermined threshold at which the perforation airflow noise generated by the flow of the air through the perforations is acceptably inaudible; and 3) arranging the perforation distribution in cooperation with configuring of the air induction housing to provide a highest level of intake noise attenuation (i.e., minimal audibility).
A significant aspect of the present invention is that the intake noise attenuation is accomplished inherently by the air induction housing, itself, obviating need for any external components of any kind (as for example an external snorkel and resonator combination of the prior art).
Accordingly, it is an object of the present invention to provide an air induction housing having a perforated wall which simultaneously provides ample air entry into the air induction housing and excellent intake noise attenuation, while attendantly minimized are expense and complexity of fabrication and assembly, as well as packaging volume.
This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment.
Referring now to the Drawing,
Turning attention next to
Further, under another principle, it is believed that to the extent the diameter D of the perforations 112 is less than any acoustic wave length λ of the noise (see
A mathematical theory believed to describe the foregoing description is as follows.
A reflection coefficient, R, is used to describe the ratio of the reflected wave to that of the incident wave (see Acoustics of Ducts and Mufflers with Application to Exhaust and Ventilation System Design, by M. L. Munjal, published by John Wiley & Sons, 1987:
R≡|R|ejθ, (1)
where |R| and θ are the amplitude and phase of the reflection coefficient, respectively.
The amplitude and phase of the reflection coefficient at an opening, i.e., the perforations, is described by the following equations:
|R|≅1−0.14ko2ro2 (2)
θ=π−tan−1(1.2koro), (3)
where ko is an initial wave number in a non-viscous fluid (i.e., air) and ro is the radius of the enclosure (i.e., the air induction housing, itself).
From equations (2) and (3), it is determined that the perforations of the perforated wall reflect the incident acoustic wave (of the engine intake noise) almost fully but with opposite phase as a reflected acoustic wave. Therefore, very little sound is emitted from the perforations because the reflected acoustic wave and subsequent incoming acoustic wave cancel one another by destructive interference.
Further, given a diameter, D, of the perforations, and given a smallest acoustic wave length, λmin, of the vast majority of the noise N, to the extent that D<λmin, all the acoustic waves having λ satisfying λmin<λ cannot exit the perforations. Accordingly, a minimum perforation diameter, D, is preferred.
However, a minimum diameter, D, of the perforations can produce noise as the airflow swiftly passes therethrough, as for example audibly detected as a howl, hiss or whistle. It is preferable that the Mach number, M, through the perforations be less than about 0.125, where M is defined by:
M=v/s, (4)
where s is the speed of sound in air and v is defined by:
v=Ψ/(ρAP), (5)
where Ψ is the maximum intake air mass flow rate of an internal combustion engine operational range divided by the number of perforations, ρ is the density of air, and AP is the area of each perforation.
Referring now to
The air induction housing 102′ has upper and lower housing components 104, 106 which are selectively sealable and separable with respect to each other (as for example via peripherally disposed clips) for servicing a filter media (not shown, but indicated at
Turning attention to
Turning attention next to
Table I shows data taken for various internal combustion engines, various selected perforation numbers and diameters for each engine, and the resulting Mach numbers associated with each of the perforation diameters and numbers selected.
It is seen from Table I that a wide range of perforation diameters can achieve a desired small Mach number. It is to be further noted that, per the above theoretical discussion, for purposes of acoustic (sound) attenuation, the smaller the perforation diameter the better. However, as mentioned hereinabove, it is necessary to adjust the area of the perforations so that the airflow (more specifically, the maximum airflow demanded of the internal combustion engine) passing through the perforations does not, itself, create undesirable noise, wherein it is preferred that the Mach number be under about 0.125 in order to achieve this result.
Thus, from Table I, it is possible to find best perforation parameters (by “best” is meant relative to the test results summarized in Table I, in that other tests may provide other “best” results): for the 4 cylinder engine is a perforated wall having 152 perforations of 5 mm diameter and having a Mach number equal to 0.111, best for the 6 cylinder engine is a perforated wall having 304 perforations of 5 mm diameter and having a Mach number equal to 0.095, best for the 8 cylinder engine is a perforated wall having 420 perforations of 5 mm diameter and having a Mach number equal to 0.086. The best for the high performance 8 cylinder engine may be a perforated wall having 420 perforations of 5 mm diameter and having a Mach number equal to 0.129, in that a Mach number of 0.129 may be acceptable (as empirically ascertained) in that engine application.
Turning attention now to
At Block 202, the algorithm is initialized. At Block 204, the engine airflow rate requirement of a selected internal combustion engine is determined. At Block 206, the necessary inlet area, AI, is determined such that back pressure is not an issue for the operation of the internal combustion engine, per the determination at Block 204. Once this area is determined, preferably about one percent (1%) is added thereto in order to account for entrance/exit airflow losses. This inlet area is the starting point for determining the number of perforations (based on average perforation area) of the perforated wall of the air induction housing.
Next, at Block 208, a minimum perforation diameter is selected using an empirical best estimation to provide a perforation area, AP. Next, at Block 210, the number, n, of perforations is calculated, wherein n=AI/AP. The smaller the perforation diameter, the better the noise attenuation benefit, as there are more waves reflected back into the box, as discussed hereinabove. However, the minimum area (and therefore diameter) of the perforations is limited by the Mach number, M, of the airflow through the perforations when at the maximum airflow rate, as discussed hereinabove.
Next, at Block 212, the Mach number, M, for the airflow through the perforations when at the maximum mass flow rate is calculated using, for example, equations (4) and (5). At Decision Block 214, inquiry is made whether the Mach number is less than, by way of preference, about 0.125. If the answer to the inquiry is no, then the algorithm returns to Block 208, whereat a new minimum perforation diameter is selected, larger than that previously selected (that is, assuming the first chosen minimum diameter was a true minimum, otherwise various larger and smaller diameters can be tried to find the minimum). However, if the answer to the inquiry is yes, then the algorithm advances to Block 216.
At Block 216, the configuration of the air induction housing is determined. In so doing, taken into account are the packaging requirements for accommodation within the engine compartment, as well as a best estimation for providing acoustic attenuation, for example, per equations (2) and (3). The shape may be any suitable and/or necessary shape, as for example an irregular polygonal shape as for example shown at
Next, at Decision Block 220, inquiry is made, for example by use of empirical testing of a modeled air induction housing, whether the sound attenuation is a maximum (i.e., sound emission at the perforations is a minimum). If the answer to the inquiry is no, then the algorithm returns to Block 218, wherein any possible reconfiguration of the air induction housing is made (if packaging constraints allow), and the perforation distribution is again reselected. However, if the answer to the inquiry at Decision Block 220 is yes, then the algorithm advances to Decision Block 224.
At Decision Block 224, inquiry is made whether the amount of sound attenuation is acceptable based upon a predetermined base line (as for example plot 122 of
It is to be understood that the perforations may have any shape or differing shapes, any area or differing areas, any diameter or differing diameters, and have uniform or non-uniform spacing therebetween, the perforated wall may be located anywhere or generally everywhere of the air induction housing, and that multiple layers of the perforated wall my be utilized, all for the purpose of tuning the intake noise emitted from the air induction system to a desired level of attenuation (acceptably inaudible) at the perforations.
To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4236597 | Kiss et al. | Dec 1980 | A |
| 4326865 | Siebels | Apr 1982 | A |
| 5260524 | Schroeder et al. | Nov 1993 | A |
| 5679931 | Furse et al. | Oct 1997 | A |
| 5681075 | Komori et al. | Oct 1997 | A |
| 5696361 | Chen | Dec 1997 | A |
| 5979598 | Wolf et al. | Nov 1999 | A |
| 6105716 | Morehead et al. | Aug 2000 | A |
| 6662892 | Falk et al. | Dec 2003 | B2 |
| 6881237 | Storz et al. | Apr 2005 | B2 |
| 20040011011 | Storz et al. | Jan 2004 | A1 |
| 20060032700 | Vizanko | Feb 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| 2003002292 | Jan 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20080210188 A1 | Sep 2008 | US |
