JPH08326521A - Exhaust muffler - Google Patents

Abstract

PURPOSE: To weaken exciting force applied to a shell so as to reduce radiation sound by disposing a resonance chamber with low internal sound pressure on the outside of an expansion chamber with high internal sound pressure. CONSTITUTION: A cylindrical small diameter inner shell 2 is coaxially provided in a cylindrical large diameter outer shell 1, and both ends of the shells 1, 2 are respectively covered with end plates 3A, 3B. A large number of small holes 5 are bored in an exhaust pipe 4 provided in the inner shell 2 while piercing the respective end plates 3A, 3B. An expansion chamber 6 formed in the inner shell 2, and a resonance chamber 8 formed between the respective shells 1, 2 are connected to each other through a neck pipe 7. Since the peirpheral side of the expansion chamber 6 with high internal sound pressure is covered with the resonance chamber 8, exciting force applied to the outer shell 1 is lowered to reduce radiation sound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust muffler for reducing exhaust noise, and more particularly, an exhaust muffler having two types of muffler elements having different internal sound pressure levels inside a shell, such as an expansion chamber and a resonance chamber. The present invention relates to an improvement of a muffler, and more particularly to an exhaust muffler suitable for automobiles.

[0002]

2. Description of the Related Art In a vehicle equipped with an internal combustion engine, in order to reduce exhaust noise when exhaust gas burned in a cylinder of the engine body is released into the atmosphere, exhaust gas is exhausted midway through an exhaust pipe passing under the floor of the vehicle. A silencer is provided. Also, as the exhaust silencer, an expanded silencer structure (expansion silencer structure) that expands the volume in the middle of the exhaust system is adopted, a resonance silencer structure in which a resonator is connected in the middle of the exhaust system. In addition to the one adopting the above-mentioned method, a combination of these methods is known as described in, for example, Japanese Utility Model Laid-Open No. 59-102923.

Therefore, as a conventional vehicle exhaust muffler, the one described in the above publication will be described with reference to FIG.

That is, FIG. 8 is a cross-sectional view of a conventional exhaust muffler for an automobile, in which both end faces of a tubular shell 100 having a substantially elliptical cross section are welded to one end. 1
01A and the other end plate 101B welded to the other end, respectively, and the inside of the shell 100 is located at the left side in the drawing by an elliptical partition plate 102.
03 and a resonance chamber 104 located on the right side in the figure.

An inlet pipe 105 provided through the other end plate 101B communicates with the inside of the expansion chamber 103, and an outlet pipe 106 provided through the one end plate 101A and the partition plate 102. Also communicates with the expansion chamber 103. Therefore, the inlet pipe 105 and the outlet pipe 106 are connected to each other through the expansion chamber 103, so that an expansion type sound deadening element is configured. The inlet pipe 105 is connected to an exhaust port (not shown) of the engine body via an exhaust manifold, a catalytic converter and the like.

The partition plate 102 has an extension chamber 103 and a resonance chamber 10 adjacent to one end of the extension chamber 103 in the axial direction.
4 is provided with a neck tube 107 that communicates with each other, and the neck tube 107 and the resonance chamber 104 constitute a resonance-type silencing element.

An exhaust muffler for a vehicle according to the prior art is
With the above-mentioned configuration, the exhaust gas discharged from the exhaust port of the engine body flows into the inlet pipe 105 through the catalytic converter and the like, and flows out from the inlet pipe 105 into the expansion chamber 103 having a large volume. Is expanded by the outlet pipe 10
It is released from the rear of the vehicle body into the atmosphere via 6. In the exhaust gas outflow process in the shell 100 and the like, the acoustic energy of the exhaust gas is attenuated by the expansion-type silencing element and the resonance-type silencing element, whereby the exhaust sound is silenced.

[0008]

By the way, in the exhaust muffler for an automobile according to the above-mentioned prior art, the shell 100 is used.
By providing the expansion chamber 103 and the resonance chamber 104 therein, exhaust noise is eliminated and reduced, but the expansion chamber 103 and the resonance chamber 104 are simply arranged adjacent to each other in the axial direction of the shell 100. Since it is not too much, as shown in FIG.
There is a possibility that the radiated sound S radiated from the outer surface of the expansion chamber 103 becomes large and the noise is worsened. That is, as will be described later with reference to FIG. 3, the internal sound pressure inside the expansion chamber 103 where the exhaust gas expands rapidly becomes higher than the sound pressure inside the resonance chamber 104, and this high internal sound pressure causes the shell 1
00 (more accurately, the expansion chamber 103 of the shell 100)
The portion surrounding the) is directly and strongly vibrated, which may cause a large radiated sound. In other words, according to the prior art, even if the resonance chamber having a relatively low internal sound pressure is provided, it is used only for reducing exhaust noise, and is not used as a means for suppressing radiation noise. .

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide an exhaust silencer capable of reducing the radiated sound by weakening the vibration force applied to the shell. It is in.

[0010]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a shell by covering around or a specific portion of a sound deadening element such as an expansion chamber having a high internal sound pressure with a sound deadening element such as a resonance chamber having a low internal sound pressure. We decided to suppress the radiated sound by weakening the excitation force applied to. That is, the structure adopted by the exhaust silencer according to the present invention is different in the strength of the internal sound pressure formed in this shell from the cylindrical shell provided in the middle of the exhaust pipe and closed at both ends. In an exhaust silencer including two types of muffling elements, a specific part of the two types of muffling elements having a higher internal sound pressure is replaced by a muffling element having a relatively lower internal sound pressure. It is characterized by covering.

According to the second aspect of the present invention, the exhaust silencer is provided with a tubular shell provided in the middle of the exhaust pipe and closed at both ends, and an expansion chamber and a resonance chamber formed in the shell. In the above, the resonance chamber is provided so as to cover the outside of the expansion chamber.

Further, according to a third aspect of the present invention, the exhaust gas is provided with a cylindrical shell provided in the middle of the exhaust pipe and having both ends closed, and an expansion chamber and a resonance chamber formed in the shell. In the muffler, the resonance chamber is provided so as to cover the lower side of the expansion chamber.

Further, according to a fourth aspect of the present invention, a large-diameter cylindrical outer shell, a small-diameter cylindrical inner shell provided in the outer shell, and the outer shell and both end surfaces of the inner shell are closed. End plates provided in the inner shell, the exhaust pipe inserted through the end plates into the inner shell, and a large number of small holes formed in the inner shell, the outer shell and the inner shell. It comprises a neck tube which communicates with a first chamber defined between the shell and a second chamber defined in the inner shell.

According to a fifth aspect of the present invention, a large-diameter cylindrical outer shell, a small-diameter cylindrical inner shell provided in the outer shell, and one end surface and the other end surface of the outer shell and the inner shell are closed. The one end plate and the other end plate provided in the inner shell and the first chamber located in the inner shell at one end side and in the middle part A partition plate that divides into a second chamber and a third chamber located on the other end side, an inlet pipe that penetrates the other end plate and is inserted into the inner shell, and communicates with the first chamber, A tail pipe that penetrates through the one side end plate and is inserted into the inner shell and that communicates with the third chamber, and the partition plates are provided so as to respectively penetrate the first chamber and the second chamber. A communication for communicating with the chamber and between the second chamber and the third chamber And the tube is constituted by a neck tube for communicating image made a cylindrical chamber and a second chamber between the outer shell and the inner shell.

Further, according to a sixth aspect of the present invention, a tubular shell, one end plate and the other end plate provided by closing one end surface and the other end surface of the shell, and the lower side of the shell A partition plate for partitioning the inside of the shell into a first internal space located on the upper side and a second internal space located on the lower side; and a partition plate provided in the shell in an axially spaced manner, A partition plate that divides the first internal space into a first chamber located on one end side, a second chamber located on the middle part and a third chamber located on the other end side, and the other end plate An inlet pipe that penetrates through the first internal space and communicates with the first chamber and the one end plate through the first internal space, and then the third internal space. A tail pipe that communicates with the chamber and the partition plates are provided so as to pass through the space between the first chamber and the second chamber and the second chamber. A communicating pipe for communicating between the chamber and the third chamber are constituted by a neck tube for communicating the said second chamber and said second internal space.

[0016]

[Function] The specific part of the silencing element with the stronger internal sound pressure is
According to the structure of claim 1, which is covered by the muffling element having a relatively weak internal sound pressure, the exciting force applied to the portion of the wall surface of the shell covered by the muffling element having a weak sound pressure is weakened, and the radiated sound is emitted. Is reduced. Here, the “specific part” means a region in which radiation noise reduction is required. Therefore, for example, when it is necessary to reduce the radiated sound over the entire surface, the entire outer surface of the sound deadening element having a strong sound pressure becomes a “specific portion”, and the entire outer surface has a specific area such as the lower surface side. In the case where only the radiation sound reduction is sufficient, the specific region becomes the “specific part”.

According to the structure of claim 2, wherein the resonance chamber is provided so as to cover the outside of the expansion chamber, the resonance chamber having a low sound pressure is located immediately inside the shell, so that the force for exciting the shell is exerted. Is weakened, and the radiated sound can be suppressed.

According to the third aspect of the present invention, the resonance chamber is provided so as to cover the lower side of the expansion chamber. Among the radiated sounds, the radiated sound generated particularly in the lower part can be reduced and the radiated sound generated in the upper part. Sound can be absorbed by the vehicle body and other structures.

A double cylinder structure of an outer shell and an inner shell, wherein a second chamber, which is an expansion chamber defined in the inner shell, is covered with a second chamber, which is a resonance chamber defined between the shells. According to the configuration of Item 4, the radiated sound can be reduced as in the case of Claim 1.

A double cylinder structure of an outer shell and an inner shell is provided, and a first chamber and a second chamber which are expansion chambers are provided in the inner shell.
6. The chamber and the third chamber are defined, and each of these chambers is covered with a cylindrical chamber that is a resonance chamber formed between the shells.
According to this configuration, the exhaust sound can be silenced by the plurality of expansion chambers, and the internal sound pressure can be reduced to suppress the radiated sound as described above.

In addition, a first chamber, a second chamber and a third chamber which are expansion chambers are defined inside the shell, and a second internal space which is a resonance chamber is provided below each of these chambers. According to the structure of claim 6, the exhaust noise can be suppressed by the plurality of expansion chambers as in the case of claim 5, and the radiation sound radiated on the lower side can be reduced.

[0022]

Embodiments of the present invention will now be described in detail with reference to FIGS.

First, FIGS. 1 to 3 relate to a first embodiment of the present invention, and FIG. 1 is a sectional view of an exhaust silencer applied to an automobile according to this embodiment, as shown in FIG. Inside a large-diameter cylindrical outer shell 1 having a substantially elliptical cross-section, a small-diameter cylindrical inner shell 2 having a substantially elliptical cross-section is coaxially arranged. In addition, one end surface of each shell 1 and 2 has one end plate 3
In addition to being capped by A, the other end surfaces of the shells 1, 2 are capped by the other end plate 3B, and these end plates 3A, 3B are secured by welding or the like to the shell 1, 1.
It is fixed to the edge of the opening 2.

Further, one continuous exhaust pipe 4 passes through substantially the axial center of the inner shell 2 and one end plate 3A and the other end plate 3B.
And is fixed to the opening edge portions of the respective end plates 3A and 3B by fixing means such as welding. This exhaust pipe 4
Is connected to an exhaust port (not shown) of the engine body via an exhaust manifold, a catalytic converter, and the like. Further, in the middle of the exhaust pipe 4, a large number of small holes 5 are formed in the peripheral surface of the portion located inside the inner shell 2.

The interior of the inner shell 2 communicates with the exhaust pipe 4 through the large number of small holes 5, so that the chamber inside the inner shell 2 is an expansion chamber 6 as a "second chamber".
Is composed. In the illustrated example, the case where the small holes 5 are formed to have the same diameter is illustrated, but the invention is not limited to this.
A large number of small holes having different diameters may be formed in consideration of the frequency range to be attenuated.

A short neck pipe 7 is provided so as to pass through the inner shell 2 above the axially intermediate portion of the inner shell 2. The neck pipe 7 has an opening edge portion (the neck pipe 7 is It is fixed to the (penetrating portion) by fixing means such as welding. The tubular chamber between the outer shell 1 and the inner shell 2 is communicated with the expansion chamber 6 in the inner shell 2 via the neck pipe 7, so that the tubular chamber is the “first chamber”. The resonance chamber 8 as The shells 1 and 2, the end plates 3A and 3B, the exhaust pipe 4, and the neck pipe 7 are usually formed of steel plates and fixed by welding, but the invention is not limited to this, and the heat resistance and the like are not limited thereto. If the characteristics required for the exhaust silencer are satisfied, it may be formed of ceramics or the like, or other fixing means such as adhesion, welding, or caulking may be used.

Next, the operation of the vehicle exhaust muffler according to this embodiment will be described. Exhaust gas discharged from the exhaust port of the engine body enters the inner shell 2 through the exhaust pipe 4 in the direction of arrow A. Inflow. Then, the exhaust gas flowing in the exhaust pipe 4 flows into the expansion chamber 6 having a larger volume than the exhaust pipe 4 through the large number of small holes 5, and the acoustic energy is attenuated. The acoustic energy is also attenuated by the resonance chamber 8 provided on the outer peripheral side of the expansion chamber 5. And
Exhaust gas whose acoustic energy is weakened in this way
It is released into the atmosphere through the exhaust pipe 4.

Here, FIG. 3 is a characteristic diagram showing the levels of the near-field radiated sound when the interior of the exhaust silencer is constructed as an extended silencer and when it is constructed as a resonance silencer. Whichever type is used, the noise level increases as the engine speed increases, but the noise level is higher in the expanded type indicated by the solid line than in the resonance type indicated by the broken line. Is about 20 dB higher. Therefore,
In the embodiment, the expansion chamber 6 serves as a “silencing element having a stronger internal sound pressure” and the resonance chamber 8 serves as a “silencing element having a relatively weaker internal sound pressure”.

That is, it can be understood that when the exhaust silencer has an internal structure of resonance type, the internal sound pressure is lower than that of the expansion type, and the force for vibrating the outer shell 1 is smaller.

According to the present embodiment configured as described above,
The following effects are obtained.

First, since the resonance chamber 8 as a silencing element having a low internal sound pressure is provided so as to cover the outside of the expansion chamber 6 as a silencing element having a high internal sound pressure, the sound pressure inside the outer shell 1 is reduced. It is possible to arrange the low resonance chamber 8, whereby the vibration force applied to the outer shell 1 can be weakened and the radiated sound can be reduced. Specifically, since the outer peripheral side of the expansion chamber 6 is entirely covered with the resonance chamber 8, the radiated sound generated in the outer shell 1 can be suppressed. That is, by arranging the resonance chamber 8 which is a silencing element having a low internal sound pressure so as to cover the outside of the expansion chamber 6 which is a silencing element having a high internal sound pressure, the exciting force applied to the outer shell 1 which is the outermost shell is arranged. We can weaken and reduce radiated sound.

Secondly, a large-diameter cylindrical outer shell 1 and a small-diameter cylindrical inner shell 2 provided in the outer shell 1.
And a plurality of small holes 5 are formed in the middle of the exhaust pipe 4 inserted in the inner shell 2, and the expansion chamber 6 in the inner shell 2 and each shell 1, 2 are formed. Since the resonance chamber 8 communicates with the neck tube 7, the outer peripheral side of the expansion chamber 6 can be easily surrounded by the cylindrical resonance chamber 8, and the radiated sound can be effectively reduced with a relatively simple structure. be able to.

Next, a second embodiment of the present invention will be described with reference to FIGS. In each of the following embodiments, the same components as those in the first embodiment are designated by the same reference numerals,
The description will be omitted. The feature of this embodiment is that a plurality of expansion chambers are formed and the outside of all of these expansion chambers is covered with a resonance chamber.

That is, FIG. 4 is a cross-sectional view of an automobile exhaust muffler according to this embodiment. As in the case of the first embodiment, the large-diameter cylindrical shell 1 is coaxial with the small-diameter cylindrical shape. A shell 2 is provided, and both end faces of each of the shells 1 and 2 are covered with one end plate 11A and the other end plate 11B, but inside the inner shell 2, a plurality of expansion chambers 13, which will be described later,
This embodiment is different from the above embodiment in that 14 and 15 are formed.

Inside the inner shell 2, two partition plates 1 are formed in a substantially elliptical shape along the shape of the inner shell 2.
2A and 12B are separated from each other in the axial direction and fixed to each other by welding or the like. Inside of the inner shell 2 is defined as a "first chamber" located on one side in the axial direction by the partition plates 12A and 12B. First expansion chamber 13 and a second expansion chamber 14 as a "second chamber" located at an intermediate portion in the axial direction.
And a third expansion chamber 15 as a "third chamber" located on the other side in the axial direction are formed in the axial direction. More specifically, the first expansion chamber 13 is defined between the one side end plate 11A and the one side partition plate 12A, and the second expansion chamber 13 is formed between the one side partition plate 12A and the other side partition plate 12B. The expansion chamber 14 is defined, and the third expansion chamber 15 is defined between the other side partition plate 12B and the other side end plate 11B. Further, the first expansion chamber 13 and the third expansion chamber 15 located at both ends in the axial direction are formed with substantially the same volume, and the second expansion chamber 14 located in the middle portion has the expansion chambers 13 and 15 respectively. Is formed to have a volume approximately twice that of

Inlet pipe 16 connected to an exhaust port of the engine body via a catalytic converter (neither is shown) or the like
Is inserted into the inner shell 2 by penetrating the upper side of the other side end plate 11B and each of the partition plates 12A, 12B, and the tip 16A at one end side thereof is open in the first expansion chamber 13. Further, the inlet pipe 16, the other end plate 11B and each partition plate 12A,
It is fixed to the opening edge of 12B by fixing means such as welding.

The tail pipe 17 is inserted into the inner shell 2 by penetrating the lower side of the one end plate 11A and the partition plates 12A and 12B, and the tip 17A at the other end side is inside the third expansion chamber 15. It is open. In addition, like the inlet pipe 16, the tail pipe 17
The end plate 11A on one side and the opening edges of the partition plates 12A and 12B are fixed to each other by welding or the like.

Further, short communication pipes 18A and 18B are provided so as to penetrate through the partition plates 12A and 12B, respectively, so that the adjacent expansion chambers communicate with each other. More precisely, the inlet pipe 16 and the tail pipe 1 are provided on the one side partition plate 12A.
The one side communication pipe 18A is provided so as to be located between the first expansion chamber 13 and the second expansion chamber 14, and the one side communication pipe 18A communicates with the first expansion chamber 13 and the second expansion chamber 14. On the other hand, in the other side partition plate 12B, similarly, the other side communication pipe 18B is provided so as to be located between the inlet pipe 16 and the tail pipe 17, and the second expansion is performed by the other side communication pipe 18B. The chamber 14 and the third expansion chamber 15 communicate with each other. These communication pipes 18A, 18B
Is fixed to the opening edge portions of the partition plates 12A and 12B by a fixing means such as welding, and as shown in the sectional view of FIG. 5, the communication pipes 18A and 18B, the inlet pipe 16 and the tail pipe 17 are , Are separated from each other in the width direction (left and right direction in FIG. 5).

A short neck tube 19 is provided so as to penetrate through the axially intermediate portion of the inner shell 2, and the neck tube 19 is fixed to the opening edge portion of the inner shell 2 by welding or the like. The tubular chamber between the outer shell 1 and the inner shell 2 communicates with the second expansion chamber 14 via the neck pipe 19, so that the tubular chamber between the shells 1 and 2 is The resonance chamber 20 as a "chamber" is configured.

The exhaust silencer for a vehicle according to this embodiment is
With the above-described configuration, the exhaust gas that flows in through the inlet pipe 16 is the first expansion chamber 13 → the one-side communication pipe 18A →
2nd expansion chamber 14-> other side communication pipe 18B-> 3rd expansion chamber 1
It flows while repeating expansion and contraction to 5, and finally the tail tube 17
Is released into the atmosphere via.

Also in this embodiment having such a structure, the outer peripheral sides of the plurality of expansion chambers 13, 14, 15 having a high internal sound pressure are covered with the cylindrical resonance chamber 20 having a low internal sound pressure. 1
Similarly to the embodiment described above, the vibration force applied to the outer shell 1 can be weakened, and as a result, the radiated sound can be suppressed. In addition to this, in the present embodiment, since the plurality of expansion chambers 13, 14, 15 are arranged in series in the inner shell 2, the first embodiment is performed by the plurality of expansion chambers 13, 14, 15. Exhaust muffling performance can be made higher than in the example.

Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the same components as those in the second embodiment described above are designated by the same reference numerals, and the description thereof will be omitted. The feature of this embodiment is that a plurality of expansion chambers are formed in the shell and a resonance chamber is provided so as to cover the lower side of each expansion chamber.

That is, FIG. 6 is a cross-sectional view of an automobile exhaust muffler according to the present embodiment, in which both ends of a shell 31 having a substantially elliptical cross-section have one side end welded to one end thereof. The cover is covered by the plate 32A and the other end plate 32B welded to the other end.

Further, as shown in FIG. 7, below the shell 31, a flat plate-shaped dividing plate 33 is provided over the entire length of the shell 31, and both side edges of the dividing plate 33 are formed on the inner wall of the shell 31. It is fixed by fixing means such as welding. And
The partition plate 33 divides the inside of the shell 31 into a first internal space 34 located on the upper side and a second internal space 35 located on the lower side.

Inside the shell 31, the first internal space 3
Two partition plates 36A formed along the sectional shape of 4;
36B are separated from each other in the axial direction and are fixed to each other by welding or the like. As in the second embodiment, the partition plates 36A and 36B are positioned inside the shell 31 on one axial side. First expansion chamber 3 as the "first chamber"
7, a second expansion chamber 38 as a "second chamber" located in the middle portion in the axial direction, and a "third chamber" located on the other side in the axial direction.
And the third expansion chamber 39 is formed side by side in the axial direction. More specifically, the one side end plate 32A and the one side partition plate 3
6A, a first expansion chamber 37 is defined, a second expansion chamber 38 is defined between the one side partition plate 36A and the other side partition plate 36B, and the other side partition plate 36B and the other side partition plate 36B are defined. A third expansion chamber 39 is defined between the end plate 32B and the end plate 32B. Further, similar to the second embodiment, the first expansion chambers 3 located at both axial ends are provided.
The 7th and 3rd expansion chambers 39 are formed with substantially the same volume, and the 2nd expansion chamber 38 is each expansion chamber 37,3.
It is formed to have a volume that is approximately twice that of 9.

A short neck pipe 40 is provided penetrating the axially intermediate portion of the dividing plate 33 at the widthwise intermediate portion of the dividing plate 33. The neck pipe 40 is provided at the opening edge portion of the dividing plate 33. It is fixed by welding or the like. The second expansion chamber 38 and the second internal space 35 communicate with each other through the neck pipe 40, so that the second internal space 35 constitutes a resonance chamber which is a silencing element having a low internal sound pressure. ing.

The exhaust silencer for a vehicle according to this embodiment is
With the above-described configuration, the exhaust gas flowing in through the inlet pipe 16 has the first expansion chamber 37 → the one-side communication pipe 18A → the second expansion chamber 38 → as in the second embodiment. It flows while repeating expansion and contraction from the other side communication pipe 18B to the third expansion chamber 39, and finally is released into the atmosphere via the tail pipe 17.

Thus, also in this embodiment having such a configuration, since a plurality of expansion chambers 37, 38, 39 are provided in series in the shell 31, these expansion chambers 37, 38, 39 are formed.
As a result, exhaust noise reduction can be reduced more than in the first embodiment. In addition to this, in the present embodiment, a second internal space 35 that serves as a resonance chamber having a low internal sound pressure is provided so as to cover the lower side of each of the expansion chambers 37, 38, 39 having a high internal sound pressure. Therefore, the vibration force applied to the lower side of the shell 31 can be reduced and the radiation sound emitted downward can be suppressed.

In this embodiment, unlike the second embodiment, since the resonance chamber is not arranged above the expansion chambers 37, 38, 39, the radiation sound itself above the shell 31 is generated. Cannot be reduced. However, in the space above the shell 31, as shown in FIG. 7, in addition to the vehicle body (not shown), for example, the fuel tank 41 and the propeller shaft 4 are provided.
Since various structures such as 2 are arranged by effectively utilizing the narrow space, it is possible to form a pseudo muffling element by these vehicle bodies and the like, and thereby the radiation sound generated above the shell 31 can be generated. Can be absorbed to some extent.

That is, the lower side of the shell 31 directly faces the road surface 43, and the radiated sound generated on the lower side of the shell 31 collides with the road surface 43 as it is without being absorbed by any structure. Since the noise is aggravated if it is left as it is reflected, the vehicle body or the like is arranged in the space above the shell 31, so that the vehicle body or the like may vary depending on the arrangement relationship of the vehicle body or the like and the frequency of the radiated sound to be reduced. It is possible to utilize the damping effect of acoustic energy due to. In other words, depending on the arrangement relationship of various structures, an expansion-type silencing element, a resonance-type silencing element, or an element similar thereto is formed above the shell 31, so that the attenuation frequency of these incidental or additional exhaust silencing elements is reduced. If the range corresponds to the frequency of the radiated sound, the radiated sound can be reduced.

Therefore, in the present embodiment, the second inner space 35 as a resonance chamber formed below the shell 31 suppresses the radiated sound on the lower side, and at the same time, the vehicle body placed in the space above the shell 31. The radiated sound on the upper side is suppressed by effectively using pseudo muffling elements such as. As a result, the entire structure can be simplified and the radiated sound can be efficiently reduced as compared with the second embodiment. Further, in order to effectively use the pseudo and additional noise reduction elements such as the vehicle body, it is preferable to preset the shape and arrangement position of the structure by simulation or the like.

In each of the above-mentioned embodiments, the case where the cross-sectional shape of the shell is formed into a substantially elliptical shape is illustrated, but the present invention is not limited to this, and may be formed into another shape such as a circular shape.

In the second and third embodiments, the case where the three expansion chambers 13 and the like are provided in the shell has been exemplified.
Instead of this, for example, two or four or more expansion chambers may be arranged, and the small hole 5 described in the first embodiment and the expansion chamber 13 described in the second and third embodiments. Various modifications are possible, such as a combination of the above and a sound absorbing material such as glass wool.

Further, in each of the above-mentioned embodiments, the expansion chamber is mentioned as the "silencing element having a high internal sound pressure" and the resonance chamber is exemplified as the "silencing element having a relatively weak internal sound pressure". It is not limited to this.

In the third embodiment, the case where the flat plate-shaped dividing plate 33 is used has been described as an example. However, the present invention is not limited to this, and as shown by a chain double-dashed line in FIG. 7, for example. ,
Both sides 51 of the dividing plate 33 are curved obliquely upward so that the shell 3
A second internal space, which is a resonance chamber, may be arranged on the side of 1.

[0056]

As described in detail above, according to the exhaust silencer of the present invention, a specific portion of the silencing element having a higher internal sound pressure is covered with the silencing element having a relatively weaker internal sound pressure. Due to the configuration, it is possible to suppress the radiated sound by weakening the excitation force applied to the shell wall surface corresponding to the specific portion.

Further, in the structure of claim 2 in which the resonance chamber is provided so as to cover the outside of the expansion chamber, the force for vibrating the shell can be weakened and the radiated sound can be suppressed.

Further, in the structure of claim 3 in which the resonance chamber is provided so as to cover the lower side of the expansion chamber, the radiated sound generated below can be reduced and the radiated sound generated above can be absorbed by the vehicle body or the like. Therefore, the entire structure can be simplified.

A double cylinder structure of an outer shell and an inner shell, wherein a second chamber, which is an expansion chamber defined in the inner shell, is covered with a second chamber, which is a resonance chamber defined between the shells. With the configuration of Item 4, the radiated sound can be reduced as in the case of Claim 1.

A double cylinder structure of an outer shell and an inner shell is used, and a first chamber and a second chamber which are expansion chambers are provided in the inner shell.
6. The chamber and the third chamber are defined, and each of these chambers is covered with a cylindrical chamber that is a resonance chamber formed between the shells.
According to this configuration, the exhaust gas can be silenced by the plurality of expansion chambers, and the radiated sound can be suppressed by lowering the internal sound pressure.

In addition, a first chamber, a second chamber and a third chamber which are expansion chambers are defined inside the shell, and a second internal space which is a resonance chamber is provided below each of these chambers. According to the configuration of claim 6, the exhaust gas can be silenced by the plurality of expansion chambers as in the case of claim 5, and the radiation sound radiated on the lower side can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an exhaust silencer according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a characteristic diagram showing a relationship between a sound deadening structure inside a shell and a noise level.

FIG. 4 is a sectional view of an exhaust silencer according to a second embodiment of the present invention.

5 is a sectional view taken along the line VV in FIG.

FIG. 6 is a sectional view of an exhaust silencer according to a third embodiment of the present invention.

FIG. 7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is a cross-sectional view of an exhaust silencer according to the related art.

[Explanation of symbols]

 1 ... Outer shell 2 ... Inner shell 3A, 3B, 11A, 11B, 32A, 32B ... End plate 4 ... Exhaust pipe 5 ... Small hole 6, 13, 14, 15, 37, 38, 39 ... Expansion chamber 12A, 12B, 36A , 36B ... Partition plate 16 ... Inlet pipe 17 ... Tail pipe 18A, 18B ... Communication pipe 19, 40 ... Neck pipe 20 ... Resonance chamber 31 ... Shell 33 ... Dividing plate 34 ... First internal space 35 ... Second internal space

Claims (6)

[Claims] 1. An exhaust system comprising a tubular shell provided in the middle of an exhaust pipe, the ends of which are closed, and two types of silencing elements having different internal sound pressure intensities formed in the shell. In the silencer, the exhaust silencer is characterized in that, of the two types of silencer, a specific part of the silencer having a higher internal sound pressure is covered with the silencer having a relatively lower internal sound pressure. 2. An exhaust muffler comprising a tubular shell provided in the middle of an exhaust pipe, the ends of which are closed, and an expansion chamber and a resonance chamber formed in the shell. An exhaust silencer, wherein the resonance chamber is provided so as to cover the outside. 3. An exhaust silencer comprising a tubular shell provided in the middle of an exhaust pipe and having both ends closed, and an expansion chamber and a resonance chamber formed in the shell. An exhaust silencer, wherein the resonance chamber is provided so as to cover the lower side. 4. A large-diameter cylindrical outer shell, a small-diameter cylindrical inner shell provided in the outer shell, end plates provided by closing both end surfaces of the outer shell and the inner shell, and each of these. An exhaust pipe that penetrates through the end plate and is inserted into the inner shell, and has a large number of small holes formed in a portion located inside the inner shell; and a first partition defined between the outer shell and the inner shell. Exhaust muffler comprising a neck tube for communicating the chamber of No. 2 with a second chamber defined in the inner shell. 5. A large-diameter cylindrical outer shell, a small-diameter cylindrical inner shell provided in the outer shell, and one end plate provided by closing one end surface and the other end surface of the outer shell and the inner shell. And the other end plate and the first shell located at one end side and the second room located at the intermediate portion and the other end side that are provided in the inner shell so as to be separated from each other in the axial direction. A partition plate that divides into a third chamber that is located, an inlet pipe that penetrates the other side end plate and is inserted into the inner shell, and that communicates with the first chamber, and a one side end plate. And a tail pipe that is inserted into the inner shell and that communicates with the third chamber, and the partition plates, and that is provided between the first chamber and the second chamber and the second chamber. Communication pipe for communicating between the third chamber and the third chamber, and the outer shell and the inner pipe. An exhaust muffler comprising a tubular chamber defined between the shell and a nacelle and a neck pipe communicating the second chamber. 6. A tubular shell, one side end plate and the other side end plate that are provided by closing one end surface and the other end surface of the shell, and the inside of the shell that is provided below the shell. A partition plate that divides into a first internal space located on the upper side and a second internal space located on the lower side, and a partition plate provided in the shell in the axial direction so as to be separated from each other. A first chamber located on one side, a second chamber located on the middle side and a third chamber located on the other end side, and a partition plate penetrating the other end plate and the first interior The first is inserted into the space
Of the inlet pipe communicating with the chamber of No. 2, the tail pipe penetrating the one end plate and inserted into the first internal space, and communicating with the third chamber, and the partition plates. A communication pipe that is provided to communicate between the first chamber and the second chamber and between the second chamber and the third chamber; and the second internal space and the second chamber. An exhaust muffler that includes a neck pipe that communicates with each other.