1. Field of the Invention
The invention relates to a silencing apparatus for a vehicle, which includes a muffler having a flattened sectional shape in which the width is greater than the height, an inlet pipe through which exhaust gas flows into an inside of the muffler, an outlet pipe through which the exhaust gas flows out of the inside of the muffler, a partition plate that divides the inside of the muffler into sound-deadening chambers, and a communication hole that extends through the partition plate.
2. Description of Related Art
As a silencing apparatus for a vehicle, there is a muffler provided in an exhaust system of an internal combustion engine. The muffler disposed beneath the floor of a vehicle generally has a flattened sectional shape in which the width is greater than the height, for example, an elliptical sectional shape, en elongated circular sectional shape, etc., for the sake of mountability.
A muffler having a flattened sectional shape that has a width W as shown in
In related art, as a countermeasure against high-frequency exhaust sound as in the air column resonance in the width direction of a muffler, a sub-muffler that has a high-frequency resonance structure or that is filled with a sound absorbing material is provided in the exhaust system, as in Japanese Patent Application Publication No. 2009-062922 (JP-A-2009-062922).
If the sub-muffler is appropriately designed, it is certainly possible to restrain increase of the exhaust sound that results from the air column resonances in the width direction of the muffler. However, if the sub-muffler is installed, corresponding increases in cost and mass are inevitable. Therefore, it is demanded to provide a vehicle silencing apparatus that effectively restrains the increase of exhaust sound caused by the air column resonances in the muffler width direction at a reduced cost.
The invention provides a silencing apparatus for a vehicle, which effectively restrains the increase of exhaust sound caused by air column resonances in the width direction of a muffler.
Firstly, the principle of the invention will be explained.
When focus is placed on the opening 52 provided at the position that is apart from the end by the length of W/2, a space to the right of the opening 52 in
When focus is placed on the opening 53 provided at the position that is apart from the end by the length of W/4, a space to the left side of the opening 53 is a space that is open to the outside through the opening 52 as shown in
Thus, the sound-deadening chamber 51 of the muffler 50 in which the openings 52 and 53 are formed at the above-described positions achieves the sound-absorbing effect, that is, the effect of reducing sound caused by the most conspicuous air column resonances among the air column resonances in the width direction of the muffler 50, that is, the air column resonances with the wavelength of λ=2W and the wavelength of λ=W. Therefore, by providing the muffler 50 in which openings (communication holes) leading to the outside are formed respectively at the position that is apart by the length equal to a half of the width W of the muffler 50 from one end of the muffler 50 in the width direction and the position that is apart by the length equal to a quarter of the width W from one end of the muffler 50 in the width direction, it is possible to effectively restrain the increase of exhaust sound caused by the air column resonances in the width direction of the muffler, without a need to provide a sub-muffler.
A first aspect of the invention relates to a silencing apparatus for a vehicle. This silencing apparatus includes: a muffler having a flattened sectional shape in which a width is greater than a height; an inlet pipe through which exhaust gas flows into an inside of the muffler; an outlet pipe through which the exhaust gas flows out of the inside of the muffler; and at least one partition plate that divides the inside of the muffler into a plurality of sound-deadening chambers. Each of the at least one partition plate has at least one communication hole that extends through the partition plate. Within the muffler, at least one among an opening of the inlet pipe, an opening of the outlet pipe, and the at least one communication hole is disposed at a position that is apart by a length equal to a half of the width of the muffler from one end of the muffler in a width direction of the muffler, and at least one among the opening of the inlet pipe, the opening of the outlet pipe, and the at least one communication hole is disposed at a position that is apart by a length equal to a quarter of the width of the muffler from one end of the muffler in the width direction.
As described above, within the muffler, the opening or the communication hole, which leads to the outside of the sound-deadening chamber, is disposed at each of the position that is apart by the length equal to a half of the width W of the muffler from one end of the muffler in the width direction of the muffler and the position that is apart by the length equal to a quarter or the width W from one end in the width direction. This muffler achieves a sound absorbing effect, that is, the effect of reducing sound caused by the air column resonances with a wavelength λ of 2W (λ=2W) and a wavelength λ of W (λ=W), which most conspicuously appear among the air column resonances in the width direction of the muffler. Therefore, according to the foregoing configuration, it is possible to effectively restrain the increase of exhaust sound caused by the air column resonances in the width direction of the muffler, without a need to provide a sub-muffler.
In order to more reliably achieve the effect of reducing the exhaust sound, each of the opening of the inlet pipe, the opening of the outlet pipe, and the at least one communication hole may be disposed at either the position that is apart by the length equal to a half of the width of the muffler from one end of the muffler in the width direction, or the position that is apart by the length equal to a quarter of the width of the muffler from one end of the muffler in the width direction.
In each of the sound-deadening chambers, each of the position that is apart by the length equal to a half of the width of the muffler from one end of the muffler in the width direction of the muffler and the position that is apart by the length equal to a quarter of the width of the muffler from the same end in the width direction may be a position at which the opening of the inlet pipe, the opening of the outlet pipe, or one of the at least one communication hole is disposed. In this case, in all the sound-deadening chambers, the sound absorbing effect, that is, the effect of reducing sound caused by the air column resonances with the wavelength λ of 2W (λ=2W) and the wavelength λ of W (λ=W) is achieved, so that the increase of exhaust sound caused by the air column resonances can be more reliably restrained.
A second aspect of the invention relates to a silencing apparatus for a vehicle. This silencing apparatus includes: a muffler having a flattened sectional shape in which a width is greater than a height; an inlet pipe through which exhaust gas flows into an inside of the muffler; an outlet pipe through which the exhaust gas flows out of the inside of the muffler; and at least one partition plate that divides the inside of the muffler into a plurality of sound-deadening chambers. Each of the at least one partition plate has at least one communication hole that extends through the partition plate. An opening of the inlet pipe, an opening of the outlet pipe, and the at least one communication hole are disposed within the muffler. In each of the sound-deadening chambers, at least one among the opening of the inlet pipe, the opening of the outlet pipe, and the at least one communication hole is disposed at a position that is apart by a length equal to a half of the width of the muffler from one end of the muffler in a width direction of the muffler, and at least one among the opening of the inlet pipe, the opening of the outlet pipe, and the at least one communication hole is disposed at a position that is apart by a length equal to a quarter of the width from the same end in the width direction.
In the muffler in which the opening of the inlet pipe, the opening of the outlet pipe, and the at least one communication hole are disposed as described above, the sound absorbing effect, that is, the effect of reducing sound caused by the air column resonances with the wavelength λ of 2W (λ=2W) and the wavelength λ of W (λ=W) is achieved in all the sound-deadening chambers, so that the increase of exhaust sound caused by the air column resonances can be more reliably restrained.
In a fore-aft direction of the muffler, the inside of the muffler may be divided by the at least one partition plate into the sound-deadening chambers each of which has a length in the fore-aft direction of the muffler, which is greater than or equal to a quarter of the width of the muffler. In this muffler, the air column resonance in the width direction of the muffler appears particularly conspicuously. Hence, the foregoing aspects of the invention are particularly suitably applied to a vehicle silencing apparatus that includes the muffler.
Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
Hereinafter, a silencing apparatus for a vehicle in accordance with a first embodiment of the invention will be described with reference to
As shown in
An inlet pipe 7, through which exhaust gas flows into the inside of the muffler 1, is disposed at a position that is apart by a length (W/4) equal to a quarter of the width W of the muffler 1 from a right-side end (in
In the first partition plate 2, a communication hole 9 that extends through the first partition plate 2 is formed at a center of the muffler 1 in the width direction, that is, a position that is apart by a length (W/2) equal to a half of the width W of the muffler 1 from the two opposite ends thereof in the width direction. Through the communication hole 9, the first sound-deadening chamber 4 and the second sound-deadening chamber 5 communicate with each other. The second partition plate 3 is provided with communication pipes 10 and 11 that extend through the second partition plate 3, at a position that is apart by the length (W/4) equal to a quarter of the width W of the muffler 1 from the right-side end (in
As shown in
On the other hand, as shown in
As shown in
As described above, in this muffler 1, each of the opening of the inlet pipe 7, the opening of the outlet pipe 8, the first communication pipe 10, the second communication pipe 11, and the communication hole 9 is disposed at either the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler 1 in the width direction or the position that is apart by the length equal to a quarter of the width W from one end of the muffler 1 in the width direction. In other words, in each of the first to third sound-deadening chambers 4 to 6, at least one among the opening of the inlet pipe 7, the opening of the outlet pipe 8, the communication hole formed by the first communication pipe 10, the communication hole formed by the second communication pipe 11, and the communication hole 9 is disposed at the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler 1 in the width direction, and at least one among the opening of the inlet pipe 7, the opening of the outlet pipe 8, the communication hole formed by the first communication pipe 10, the communication hole formed by the second communication pipe 11, and the communication hole 9 is disposed at the position that is apart by the length equal to a quarter of the width W of the muffler 1 from the same end of the muffler 1 in the width direction.
As described above, a sound-deadening effect, that is, the effect of reducing sound caused by the air column resonances can be achieved in a sound-deadening chamber in which openings leading to the outside of the sound-deadening chamber are formed respectively at the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler 1 in the width direction and the position that is apart by the length equal to a quarter of the width W of the muffler 1 from the same end of the muffler 1 in the width direction. Therefore, in the muffler 1 in which the openings are disposed as described above, the sound-deadening effect, that is, the effect of reducing sound caused by the air column resonances can be achieved in each sound-deadening chamber.
The following mathematical expression (1) represents a sound deadening characteristic of a sound-deadening chamber that has two openings. The left side of the expression (1) represents the sound deadening characteristic of the muffler 1, and the first term on the right side represents the sound deadening performance of the sound-deadening chamber as a closed space. The second term on the right side represents the sound deadening performance of an acoustic tube that is formed by a closed space extending from one opening to the other opening. Each of the third and fourth terms on the right side represents the sound deadening characteristic of an acoustic tube that is formed by a closed space extending from one opening to a closed end.
20 log|Z3Yf|=20 log m23+20 log|sin kW|−20 log|cos kWa|−20 log|kWb| (1)
where S2 is the sectional area of the muffler, S3 is the sectional area of the opening, m23 is an expansion ratio (=S2/S3), m is an integer equal to or greater than 1, C is 20×√T, T is the gas temperature, W is the width of the muffler, each of Wa and Wb is the length from one end of the muffler in the width direction to one opening, k is a wavelength constant (=2πf/c), Z3 is the characteristic impedance of an acoustic tube, and Yf is the equivalent open transfer admittance of a cavity portion.
On the other hand, in the case where Wa is set at a half of the width W of the muffler 1 and Wb is set at a quarter of the width W of the muffler 1, there is no region where the amount of sound deadening greatly declines, as shown in a thick solid line. This is because the frequency of the air column resonance coincides with the frequency at which the sound deadening effect of the acoustic tube formed by the closed space is achieved. The resonance frequencies when the inside of the muffler 1 is a space whose two ends are closed are represented by the following expression (2), and the resonance frequency when the inside of the muffler 1 is a space in which only one of the two ends is closed is represented by each of the following expressions (3) and (4). As is apparent from these expressions, if Wa is set at W/2 (Wa=W/2) and Wb is set at W/4 (Wb=W/4), the resonance frequencies when both ends are closed coincide with the resonance frequencies when one end is closed, so that the standing waves due to the air column resonance are reduced.
According to the silencing apparatus for a vehicle of the foregoing embodiment, the following effects can be achieved.
(1) In this embodiment, within the muffler 1, at least one among the opening of the inlet pipe 7, the opening of the outlet pipe 8, the communication hole 9, and the communication holes formed in the second partition plate 3 by the first and second communication pipes 10 and 11 is disposed at the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler 1 in the width direction. At least one among the opening of the opening of the inlet pipe 7, the opening of the outlet pipe 8, the communication hole 9, and the communication holes formed in the second partition plate 3 is disposed at the position that is apart by the length equal to a quarter of the width W from one end of the muffler 1 in the width direction. Therefore, according to the foregoing configuration, it is possible to effectively restrain the increase of exhaust sound that is caused by the air column resonances in the width direction of the muffler, without a need to provide a sub-muffler.
(2) In this embodiment, each of the opening of the inlet pipe 7, the opening of the outlet pipe 8, the communication hole 9, and the communication holes formed in the second partition plate 3 by the first and second communication pipes 10 and 11 is disposed at either the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler 1 in the width direction or the position that is apart by the length equal a quarter of the width W of the muffler 1 from one end of the muffler 1 in the width direction. Therefore, the effect of reducing exhaust sound can be more reliably obtained.
(3) In the foregoing embodiment, in each of the first to third sound-deadening chambers 4 to 6, each of the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler 1 in the width direction and the position that is apart by the length equal to a quarter of the width W of the muffler 1 from the same end in the width direction is the position at which the opening of the inlet pipe, the opening of the outlet pipe, or the communication hole is disposed. That is, in the embodiment, in each of the first to third sound-deadening chambers 4 to 6, at least one among the opening of the inlet pipe, the opening of the outlet pipe, and the plurality of communication holes is disposed at the position that is apart by the length equal to a half of the width W of the muffler 1 from one end of the muffler in the width direction, and at least one among the opening of the inlet pipe, the opening of the outlet pipe, and the plurality of communication holes is disposed at the position that is apart by the length equal to a quarter of the width W from the same end in the width direction. In the muffler in which the openings and the communication holes are disposed as described above, the sound absorbing effect, that is, the effect of reducing sound caused by the air column resonances with a wavelength λ of 2W (λ=2W) and a wavelength λ of W (λ=W) is achieved in all the sound-deadening chambers, so that the increase of exhaust sound caused by the air column resonances can be more reliably restrained.
Next, a silencing apparatus for a vehicle in accordance with a second embodiment of the invention will be described in detail below with reference to
As shown in
An inlet pipe 26, through which exhaust gas flows into the inside of the muffler 20, is disposed at a position that is apart by a length (W/2) equal to a half of a width W of the muffler 20 from an upper-side end (in
The first partition plate 21 is provided with a first communication pipe 28 that extends through the first partition plate 21, at a position that is apart by a length (W/4) equal to a quarter of the width W of the muffler 20 from the upper-side end (in
As shown in
As shown in
Furthermore, as shown in
As described above, in this muffler 20, each of the opening of the inlet pipe 26, the opening of the outlet pipe 27, the first communication pipe 28, and the second communication pipe 29 is disposed at either the position that is apart by the length equal to a half of the width W of the muffler 20 from one end of the muffler 20 in the width direction or the position that is apart by the length equal to a quarter of the width W from one end of the muffler 20 in the width direction. In other words, in each of the first to third sound-deadening chambers 23 to 25, at least one among the opening of the inlet pipe 26, the opening of the outlet pipe 27, the communication hole formed by the first communication pipe 28, and the communication hole formed by the second communication pipe 29 is disposed at the position that is apart by the length equal to a half of the width W of the muffler 20 from one end of the muffler 20 in the width direction, and at least one among the opening of the inlet pipe 26, the opening of the outlet pipe 27, the communication hole formed by the first communication pipe 28, and the communication hole formed by the second communication pipe 29 is disposed at the position that is apart by the length equal to a quarter of the width W of the muffler 20 from the same end of the muffler 20 in the width direction. Therefore, in this embodiment, too, the effects described above as (1) to (3) can be achieved.
Next, a silencing apparatus for a vehicle in accordance with a third embodiment of the invention will be described in detail below with reference to
As shown in
An inlet pipe 36, through which exhaust gas flows into the inside of the muffler 30, is disposed at a position that is apart by a length (W/2) equal to a half of the width W of the muffler 30 from an upper-side end (in
The first partition plate 31 is provided with a first communication pipe 38 that extends through the first partition plate 31, at the position that is apart by the length (W/2) equal to a half of the width W of the muffler 30 from the upper-side end (
As shown in
As shown in
Furthermore, as shown in
As described above, in this muffler 30, each of the opening of the inlet pipe 36, the opening of the outlet pipe 37, the first communication pipe 38, and the second communication pipe 39 is disposed at either the position that is apart by the length equal to a half of the width W of the muffler 30 from one end of the muffler 30 in the width direction or the position that is apart by the length equal to a quarter of the width W from one end of the muffler 30 in the width direction. In other words, in each of the first to third sound-deadening chambers 33 to 35, at least one among the opening of the inlet pipe 36, the opening of the outlet pipe 37, the communication hole formed by the first communication pipe 38, and the communication hole formed by the second communication pipe 39 is disposed at the position that is apart by the length equal to a half of the width W of the muffler 30 from one end of the muffler 30 in the width direction, and at least one among the opening of the inlet pipe 36, the opening of the outlet pipe 37, the communication hole formed by the first communication pipe 38, and the communication hole formed by the second communication pipe 39 is disposed at the position that is apart by the length equal to a quarter of the width W of the muffler 30 from the same end of the muffler 30 in the width direction. Therefore, in this embodiment, too, the effects described above as (1) to (3) can be achieved.
Next, a silencing apparatus for a vehicle in accordance with a fourth embodiment of the invention will be described in detail below with reference to
As shown in
An inlet pipe 46, through which exhaust gas flows into the inside of the muffler 40, is disposed at a position that is apart by a length (W/4) equal to a quarter of the width W of the muffler 40 from an upper-side end (in
The first partition plate 41 is provided with a first communication pipe 48 that extends through the first partition plate 41, at a position that is apart by the length (W/4) equal to a quarter of the width W of the muffler 40 from a lower-side end (
As shown in
As shown in
Furthermore, as shown in
As described above, in this muffler 40, each of the opening of the inlet pipe 46, the opening of the outlet pipe 47, the first communication pipe 48, and the second communication pipe 49 is disposed at either the position that is apart by the length equal to a half of the width W of the muffler 40 from one end of the muffler 40 in the width direction or the position that is apart by the length equal to a quarter of the width W from one end of the muffler 40 in the width direction. In other words, in each of the first to third sound-deadening chambers 43 to 45, at least one among the opening of the inlet pipe 46, the opening of the outlet pipe 47, the communication hole formed by the first communication pipe 48, and the communication hole formed by the second communication pipe 49 is disposed at the position that is apart by the length equal to a half of the width W of the muffler 40 from one end of the muffler 40 in the width direction, and at least one among the opening of the inlet pipe 46, the opening of the outlet pipe 47, the communication hole formed by the first communication pipe 48, and the communication hole formed by the second communication pipe 49 is disposed at the position that is apart by the length equal to a quarter of the width W of the muffler 40 from the same end of the muffler 40 in the width direction. Therefore, in this embodiment, too, the effects described above as (1) to (3) can be achieved.
The following modifications or changes may be made to the foregoing embodiments. The arrangements of the openings of the inlet and outlet pipes and the communication holes may be made different from those in the foregoing embodiments. In such cases as well, it is possible to effectively reduce the exhaust sound caused by the air column resonances in the width direction of the muffler, as long as in each sound-deadening chamber, at least one among the opening of the inlet pipe, the opening of the outlet pipe, and at least one communication hole (opening) is disposed at a position that is apart by a length equal to a half of the width W of the muffler from one end of the muffler in the width direction, and at least one among the opening of the inlet pipe, the opening of the outlet pipe, and at least one communication hole (opening) is disposed at a position that is apart by a length equal to a quarter of the width W of the muffler from the same end in the width direction.
Although in each of the foregoing embodiments, the inside of the muffler is divided into three sound-deadening chambers, the number of sound-deadening chambers formed in the muffler may be appropriately changed. Also, the number of communication pipes and the number of communication holes may be changed. In any case, as long as in each sound-deadening chamber, at least one among the opening of the inlet pipe, the opening of the outlet pipe, and at least one communication hole (opening) is disposed at a position that is apart by a length equal to a half of the width W of the muffler from one end of the muffler in the width direction, and at least one among the opening of the inlet pipe, the opening of the outlet pipe, and at least one communication hole (opening) is disposed at a position that is apart by a length equal to a quarter of the width W of the muffler from the same end in the width direction, it is possible to effectively reduce the exhaust sound caused by the air column resonances in the width direction of the muffler.
Although in the foregoing embodiments, each sound-deadening chamber is formed so that the length thereof in the fore-aft direction of the muffler is greater than or equal to a quarter of the width W of the muffler, one or more or all of the sound-deadening chambers may be formed so that the length of each of the sound-deadening chambers in the fore-aft direction of the muffler is less than a quarter of the width W of the muffler.
In the foregoing embodiments, in each sound-deadening chamber, at least one among the opening of the inlet pipe, the opening of the outlet pipe, and at least one communication hole (opening) is disposed at a position that is apart by a length equal to a half of the width W of the muffler from one end of the muffler in the width direction, and at least one among the opening of the inlet pipe, the opening of the outlet pipe, and at least one communication hole (opening) is disposed at a position that is apart by a length equal to a quarter of the width W of the muffler from the same end in the width direction. However, if in at least one sound-deadening chamber, the air column resonance in the width direction of the muffler does not conspicuously appear, the arrangement of openings and communication holes in the at least one sound-deadening chamber may be made different from the above-described arrangements thereof.
Number | Date | Country | Kind |
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2010-287468 | Dec 2010 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB2011/003054 | 12/15/2011 | WO | 00 | 6/13/2013 |
Publishing Document | Publishing Date | Country | Kind |
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WO2012/085636 | 6/28/2012 | WO | A |
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Number | Date | Country | |
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20130270034 A1 | Oct 2013 | US |