JP2009519394A - Silencer with sound absorbing material - Google Patents

Abstract

  Disclosed is a silencer including a casing, an inlet pipe, an outlet pipe, a first partition plate having a first opening, and a second partition plate having a second opening. A first chamber communicating with the inlet pipe is defined by the first partition plate and the housing. A second chamber communicating with the outlet pipe is defined by the second partition plate and the housing. The second divider plate is spaced apart from the first divider plate to define an intermediate chamber. The silencer also includes a sound absorbing material enclosed in the intermediate chamber. Exhaust noise entering from the inlet pipe enters the first chamber, enters the intermediate chamber through the first opening, enters the second chamber through the second opening, and exits through the outlet pipe. Exhaust noise is reduced when passing through the sound absorbing material.

Description

Detailed Description of the Invention

The present invention relates to a silencer, and more specifically, to a silencer including a sound absorbing material.
BACKGROUND The descriptions in this section merely provide background information related to the present invention and do not constitute prior art.

  In order to reduce engine exhaust noise, it is known to provide a silencer in the exhaust system. However, in the case of the conventional silencer, the exhaust noise cannot be sufficiently reduced depending on the operating state. For example, the exhaust noise in the exhaust system may be low frequency when the engine speed is low, but the conventional silencer design cannot sufficiently reduce the low frequency sound. Further, excessive noise may be generated by standing waves, that is, resonance in the exhaust system. Reducing such standing waves with a silencer can be difficult because standard reflective silencer tuning techniques are generally not useful for such purposes.

  Accordingly, there is a need for a silencer that more effectively reduces exhaust noise including low frequency exhaust noise and / or standing waves within the exhaust system.

SUMMARY A vehicle exhaust system silencer includes a housing having an input wall and an output wall. A partition plate having first and second openings in the housing defines one of the input wall and the output wall and an input chamber, and defines the other of the input wall and the output wall and an output chamber. The intermediate chamber is located between the first and second partition plates and is defined by the housing. A silencer is disposed in the intermediate chamber. The inlet pipe penetrates the input wall and enters the housing and terminates in the input chamber. One end of the outlet pipe is in the output chamber, and the other end passes through the output wall and comes out of the casing.

  Other scopes of application will be apparent from the description herein. It will be understood that this description and specific examples are for illustrative purposes only and are not intended to limit the scope of the invention.

Drawings The drawings attached hereto are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

DETAILED DESCRIPTION The following description is merely exemplary in nature and is not intended to limit the invention, application, or use.

  A part of the vehicle 10 is shown in FIGS. More specifically, a part of the exhaust system 12 of the vehicle 10 is shown. The exhaust system 12 includes a silencer 14. As a matter of course, the exhaust system 12 and the silencer 14 may be included in devices other than the vehicle 10 as long as they do not depart from the scope of the present invention. As will be discussed in more detail below, the silencer 14 reduces exhaust noise in the exhaust system 12.

  The silencer 14 includes a housing 16. The housing 16 includes a first wall 18, a second wall 20, and an outer wall 22. The first wall 18, the second wall 20, and the outer wall 22 can each be made from a metal plate. The first and second walls 18 and 20 are substantially flat and have an oval shape as shown in FIG. 2, and the outer wall 22 has a tubular shape. One end of the outer wall 22 is connected to the outer periphery of the first wall 18. The other end of the outer wall 22 is connected to the outer periphery of the second wall 20. Thus, the first and second walls 18 and 20 are spaced apart from each other and arranged substantially in parallel. Further, the housing 16 defines an internal space 24 of the silencer 14 between the first and second walls 18 and 20 and the outer wall 22. The first wall 18 has an inlet opening 23 and the second wall 20 has an outlet opening 25.

  The silencer 14 also includes an inlet pipe 26. The inlet pipe 26 extends in a straight line in the axial direction and can be made from a metal pipe. Inlet pipe 26 includes a first end 28 and a second end 30. The first end 28 extends through the inlet opening 23. The first end 28 is in fluid communication with an engine (not shown) of the vehicle 10 and receives exhaust gas therefrom. The second end 30 of the inlet pipe 26 is disposed in the housing 16. As described above, the exhaust gas flows from the engine of the vehicle 10 through the inlet pipe 26 into the internal space 24 of the silencer 14 as indicated by the broken line arrows in FIG.

  Furthermore, the silencer 14 includes an outlet pipe 32. The outlet pipe 32 extends in a straight line in the axial direction and can be made from a metal tube. The outlet pipe 32 includes a first end 34 and a second end 36. The first end 34 is disposed in the housing 16. The second end 36 extends through the outlet opening 25. The second end 36 may also be in fluid communication with a tail pipe (not shown) of the vehicle 10. Therefore, the exhaust gas emitted from the engine of the vehicle 10 enters the silencer 14 through the inlet pipe 26 and exits the silencer through the outlet pipe 32, as indicated by the broken arrow in FIG.

  The silencer 14 further includes a first partition plate 38. The first partition plate 38 is substantially flat and has an oval shape as shown in FIG. The first partition plate 38 can be made from a metal plate. The outer periphery of the first partition plate 38 is connected to the outer wall 22 and seals the first partition plate 38 and the outer wall 22. In the illustrated embodiment, the first divider plate 38 is substantially parallel to both the first wall 18 and the second wall 20. Further, the first partition plate 38 is disposed separately from each of the first wall 18 and the second wall 20. In the illustrated embodiment, the first partition plate 38 is closer to the second wall 20 than the first wall 18. Accordingly, the first partition plate 38 and the housing 16 cooperate to define the first chamber 40 between the first partition plate 38, the second wall 20, and the outer wall 22. The first partition plate 38 also includes an inlet opening 42 and an outlet opening 44. The outlet pipe 32 extends through the outlet opening 44. The second end 30 of the inlet pipe 26 extends through the inlet opening 42, and the second end 30 of the inlet pipe 26 terminates in the first chamber 40. Accordingly, the inlet pipe 26 is in fluid communication with the first chamber 40.

  Furthermore, the silencer 14 includes a second partition plate 46. The second partition plate 46 is substantially flat and has an oval shape as shown in FIG. The second partition plate 46 can be made from a metal plate. The outer periphery of the second partition plate 46 is connected to the outer wall 22 and seals the second partition plate 46 and the outer wall 22. In the illustrated embodiment, the second partition plate 46 is substantially parallel to the first wall 18, the second wall 20, and the first partition plate 38. Further, the second partition plate 46 is arranged to be separated from the first wall 18, the second wall 20, and the first partition plate 38. More specifically, the second partition plate 46 is disposed between the first wall 18 and the first partition plate 38. Therefore, the second partition plate 46 and the housing 16 cooperate to define the second chamber 48 between the second partition plate 46, the first wall 18, and the outer wall 22. The second partition plate 46 includes an inlet opening 50 and an outlet opening 52. The inlet pipe 26 extends through the inlet opening 50. The first end 34 of the outlet pipe 32 extends through the outlet opening 52, and the first end 34 of the outlet pipe 32 terminates in the second chamber 48. Accordingly, the outlet pipe 32 is in fluid communication with the second chamber 48.

  As above-mentioned, the 1st and 2nd partition plates 38 and 46 are arrange | positioned mutually spaced apart. In this way, the first partition plate 38, the second partition plate 46, and the housing 16 cooperate to define the intermediate chamber 54 between the first partition plate 38, the second partition plate 46, and the outer wall 22. .

  The first partition plate 38 includes a plurality of first openings 56 as shown in FIG. As such, the first chamber 40 is in fluid communication with the intermediate chamber 54. The second partition plate 46 includes a plurality of second openings 58. As such, the intermediate chamber 54 is in fluid communication with the second chamber 48. The first and second openings 56, 58 may be any size and shape as appropriate. Further, the first opening 56 may be arranged in any composition as long as it is at an appropriate position on the first partition plate 38. Further, the second opening 58 may be arranged in any composition as long as the second opening 58 is in an appropriate position on the second partition plate 46. In addition, any number of the first and second openings 56 and 58 may be provided as long as it is an appropriate number.

  Further, the silencer 14 includes a sound absorbing material 60 indicated by cross hatching in FIG. The sound absorbing material 60 may be made of any material as long as it is a suitable material. In one embodiment, the sound absorbing material 60 is a collection of fiber bundles of a plurality of fiberglasses. Suitable fiberglass materials include, but are not limited to, ADVANTEX ™ fiberglass from Owens Corning and / or POWERTEX ™ fiberglass from DBW. The fiberglass material of the sound absorbing material 60 is often referred to in the art as a “roving” material. The individual fibers of the fiber glass of the sound absorbing material 60 are arranged apart from each other in order to improve the sound absorbing characteristics of the sound absorbing material 60.

  As shown in FIG. 1, the sound absorbing material 60 is disposed in the intermediate chamber 54 and substantially enclosed. As described above, the exhaust gas entering the muffler 14 through the inlet pipe 26 enters the first chamber 40 and then flows into the intermediate chamber 54 through the first opening 56 of the first partition plate 38. Thereafter, the exhaust gas passes through the intermediate chamber 54 and the sound absorbing material 60. Next, the exhaust gas flows into the second chamber 48 through the second opening 58, enters the outlet pipe 32, and is discharged from the vehicle 10.

  As a matter of course, a sound (exhaust noise) generated by the engine is transmitted through the exhaust system along a substantially similar route. More specifically, exhaust noise enters the silencer 14 through the inlet pipe 26. Then, this sound enters the first chamber 40 and is transmitted to the inside of the intermediate chamber 54 through the first opening 56 of the first partition plate 38. Thereafter, this sound passes through the intermediate chamber 54 and the sound absorbing material 60. Next, this sound moves through the second opening 58 into the second chamber 48, enters the outlet pipe 32, and is emitted from the vehicle 10.

  Therefore, the sound absorbing material 60 is disposed directly in a path through which most of the exhaust noise passes. It is preferable that the exhaust noise is substantially reduced when passing through the sound absorbing material 60. The sound absorbing material 60 is particularly effective in reducing low frequency sound from the engine. Furthermore, the sound absorbing material 60 also reduces standing waves generated by the engine.

  As a matter of course, exhaust noise can be further reduced by increasing the density of the sound absorbing material 60 in the intermediate chamber 54. However, the increase in the density of the sound absorbing material 60 also increases the back pressure of the exhaust system 12. Therefore, the density of the sound absorbing material 60 is adjusted so as to reduce the exhaust noise while keeping the back pressure in the exhaust system 12 within an allowable range. In one embodiment, if the volume of the intermediate chamber 54 is about 5.7 L and the mass of the sound absorbing material 60 is about 500 g, the density of the sound absorbing material 60 is about 88 g / L.

  In one embodiment, the sound absorbing material 60 is provided in the intermediate chamber 54 by blowing the fibers of the sound absorbing material 60 directly onto the intermediate chamber 54. In another embodiment, first, the sound absorbing material 60 is enclosed in a processing container such as a polyethylene bag. This container is disposed between the first and second partition plates 38 and 46, and then the first and second partition plates 38 and 46 and the container are inserted into the housing 16. This container is reduced by burning or the like during operation, and the sound absorbing material 60 remains in the intermediate chamber 54.

  In the illustrated embodiment, the inlet pipe 26 includes a plurality of side holes 62. These lateral holes 62 extend through the second end 30 of the inlet pipe 26 so as to be in fluid communication with the intermediate chamber 54. The number, size, and arrangement of the horizontal holes 62 are not limited as long as they are appropriate. The outlet pipe 32 also includes a plurality of lateral holes 64. These lateral holes 64 extend through the first end 34 of the outlet pipe 32 so as to be in fluid communication with the intermediate chamber 54. Thus, exhaust gas and exhaust noise can enter the silencer 14 through the inlet pipe 26 and travel through the side hole 62 of the inlet pipe 26, the intermediate chamber 54, and the side hole 64 of the outlet pipe 32, It goes out of the silencer 14 through the inlet pipe 32. As described above, the exhaust noise is further reduced by bypassing the first and second chambers 40 and 48 for a part of the exhaust gas and the exhaust noise. In one embodiment, as described above, most of the exhaust gas and exhaust noise passes through the first and second chambers 40, so that only a small percentage bypasses the first and second chambers 40,48. Of course, the lateral hole 62 of the inlet pipe 26 and the lateral hole 64 of the outlet pipe 32 are arbitrarily added, and the silencer 14 can function without the lateral holes 62, 64.

  Here, FIG. 3 shows a graph 63 illustrating the performance of one embodiment of the silencer 14. The data of the graph 63 is obtained by repeatedly testing the same silencer 14. The sound absorbing material 60 had different densities for each test. The graph 63 has the insertion loss, that is, the reduction or attenuation of the exhaust noise on the vertical axis. The horizontal axis represents the frequency of exhaust noise. Line 67 shows the performance of the silencer 14 including the sound absorbing material 60 having a mass of about 200 grams and a density of 32 g / L. Line 69 shows the performance of the silencer 14 with the sound absorbing material 60 having a mass of about 600 grams and a density of 96 g / L. Line 71 shows the performance of the silencer 14 including the sound absorbing material 60 having a mass of about 800 grams and a density of 128 g / L. Since the silencer 14 used in each test is the same, the volume of the intermediate chamber 54 is naturally constant. In general, the exhaust noise produced by the silencer 14 having the 200-gram sound-absorbing material 60 is maximum throughout the frequency, as indicated by the line 67. Exhaust noise produced by the silencer 14 with 600 grams of sound absorbing material 60 is smaller than this, as shown by line 69. Exhaust noise produced by the silencer 14 including the 800-gram sound-absorbing material 60 is even smaller, as indicated by the line 71. Therefore, it can be seen from FIG. 3 that the silencer 14 reduces the exhaust noise as the density of the sound absorbing material 60 increases. During the test, the exhaust system 12 was operated at about 4000 RPM by standing waves. However, when the mass of the sound absorbing material 60 was 600 grams or 800 grams, the standing waves were significantly reduced by the silencer 14. I also know. Although the graph 63 shows the performance according to only one embodiment of the silencer 14, it is understood that the silencer 14 can be adjusted so that any desired performance can be exhibited.

  Here, FIG. 4 shows a silencer 114 according to another embodiment, and the same features as the embodiment shown in FIG. 1 and FIG. The silencer 114 is substantially similar to the embodiment of FIGS. 1 and 2 except that it includes a flow through or bypass pipe 166. The once-through pipe 166 can be made from a metal pipe. The entire once-through pipe 166 is disposed in the casing 116 of the silencer 114. The first and second partition plates 138 and 146 include through-flow ports 168a and 168b, respectively. A through-flow pipe 166 extends between the through-flow ports 168a and 168b. The through-flow pipe 166 also includes a first end 170 in fluid communication with the first chamber 140 and a second end 172 in fluid communication with the second chamber 148. Therefore, the exhaust gas and the exhaust noise can pass through the through-flow or bypass pipe 166 without passing through the sound absorbing material 160.

  As shown in FIG. 4, the silencer 114 also includes a valve 174. The valve 174 is operated to connect to the second end 172 of the flow-through pipe 166 to selectively limit the flow of exhaust gas and exhaust noise through the flow-through pipe 166. The valve 174 in one embodiment includes a flap 176 that is pivotally attached to the flow-through pipe 166, for example. The valve 174 also includes a biasing member 178 such as a torsion spring. The biasing member 178 is held using pins 180 that extend into the biasing member 178 and are attached to the ends of the flanges 182a, 182b of the flow-through pipe 166. The flap 176 is sized to substantially cover the opening at the second end 172 of the flow-through pipe 166. The urging member 178 urges the flap 176 toward the opening at the second end 172 to cover the opening of the cross-flow pipe 166.

  Accordingly, the exhaust gas moves from the inlet pipe 126 to the first chamber 140 as described above. When the pressure in the first chamber 140 is relatively low, the biasing member 178 biases the flap 176 so that the flap 176 remains in a position that covers the opening at the second end 172 of the flow-through pipe 166. Therefore, as described above, substantially all the exhaust gas and exhaust noise pass through the sound absorbing material 160 and are released from the outlet pipe 132 to the outside of the silencer 114. On the other hand, when the pressure in the first chamber 140 is relatively high, the flap 176 rotates against the force of the biasing member 178, so that the exhaust gas and the exhaust noise pass through the through-flow pipe 166 and the first chamber. 140 is transmitted to the second chamber 148 and bypasses the sound absorbing material 160.

  In one embodiment, when the vehicle engine is operating at a relatively low RPM, the interior of the first chamber 140 is kept low enough to keep the flap 176 closed. In this way, the low frequency and / or standing wave due to the low engine RPM is suppressed by the sound absorbing material 160. If the vehicle RPM increases, the pressure in the first chamber 140 is increased until the flap 176 is opened. Of course, the biasing member 178 may be configured to open the valve 174 when the engine exhaust gas reaches a desired flow rate. Thus, even if the RPM increases, the back pressure in the exhaust system 112 can be suppressed and the engine performance can be improved. Also, as a matter of course, when the RPM is high as described above, the exhaust noise is not much concerned by other external noise such as wind noise.

  FIG. 5 shows a graph 184 showing the performance of the silencer 114 of FIG. The graph 184 has “tail pipe sound pressure level” (TPSPL), that is, the exhaust noise level on the vertical axis. The horizontal axis is the engine speed. The first line 186 indicates the desired maximum exhaust noise level. The second line 188 shows the performance of the silencer 114 when the valve 174 is pinned and does not open in the closed state. The third line 190 shows the performance of the silencer 114 when the valve 174 opens and closes normally. As the second line 188 shows, the exhaust noise is generally lower than the maximum exhaust noise level throughout the engine speed. However, since the valve 174 is in a closed state, it is considered that the back pressure of the exhaust system 112 has an adverse effect on the engine performance. In the illustrated embodiment, valve 174 opens at approximately 3500 RPM, as shown by line 190. Before valve 174 opens, i.e., when the engine speed is less than about 3500 RPM, the exhaust noise has not reached the desired maximum level. When the valve 174 is opened, that is, when the engine speed exceeds about 3500 RPM, the exhaust noise exceeds the maximum exhaust noise level. However, as described above, when the valve 174 is opened, the back pressure in the exhaust system 112 is lowered, so that the engine performance is improved. Further, although the exhaust noise generated when the valve 174 is open is increased, it is not bothered because it is included in external noise such as wind noise. The graph 184 represents only one embodiment of the silencer 114, and it is believed that the silencer 114 can be adjusted to provide the desired performance.

  Here, FIG. 6 shows an exhaust system 212 according to another embodiment, and components having the same characteristics as those of the embodiment shown in FIGS. As shown in the figure, the silencer 214 is connected to the inlet pipe 226 and the outlet pipe 232. More specifically, the housing 216 of the silencer 214 is disposed between the inlet pipe 226 and the outlet pipe 232. The silencer 214 is divided into a first chamber 240, a second chamber 248, and an intermediate chamber 254 located between the first and second chambers 240, 248 by the first and second partition plates 238, 246. . The first partition plate 238 includes a plurality of first openings 256, and the second partition plate 246 includes a plurality of second openings 258. Inlet pipe 226 terminates in first chamber 240 so as to be in fluid communication with first chamber 240. Outlet pipe 232 terminates in second chamber 248 so as to be in fluid communication with second chamber 248. The sound absorbing material 260 is enclosed in the intermediate chamber 254.

  Therefore, exhaust gas and exhaust noise enter the first chamber 240 from the inlet pipe 226, enter the intermediate chamber 254 through the first opening 256, pass through the sound absorbing material 260, and pass through the second opening 258 to the second chamber. Enter 248 and exit through outlet pipe 232. Of course, the exhaust noise is reduced when passing through the sound absorbing material 60. Of course, the cross-sectional area of the housing 216 of the silencer 214 is substantially larger than the cross-sectional areas of the inlet pipe 226 and the outlet pipe 232. This reduces the back pressure generated within the exhaust system 212 during operation.

  Here, FIG. 7 shows an exhaust system 312 according to another embodiment, and components similar to those of the embodiment shown in FIG. 1 and FIG. The exhaust system 312 is substantially similar to the embodiment shown in FIG. 7 except that the silencer 314 includes a flow-through or bypass pipe 366 similar to the embodiment shown in FIG. The through-flow pipe 366 extends through the first partition plate 338 and the second partition plate 346 so as to be in fluid communication with both the first and second chambers 340 and 348. The valve 374 is disposed in the second chamber 348. Therefore, during operation, when the engine speed is low, the valve 374 is kept closed, and the exhaust gas and the exhaust noise substantially pass through the sound absorbing material 360. However, if the pressure in the first chamber 340 is sufficiently high, the pressure causes the valve 374 to open, so that a part of the exhaust gas and the exhaust noise moves through the through-flow pipe 366. The back pressure drops.

  Here, FIG. 8 shows an exhaust system 412 according to another embodiment, and components similar to those of the embodiment shown in FIG. 1 and FIG. As illustrated, the silencer 414 includes a first partition plate 438 and a second partition plate 446. The first partition plate 438 includes a plurality of first openings 456, and the second partition plate 446 includes a plurality of second openings 458. The intermediate chamber 454 is defined between the first and second partition plates 438 and 446. The sound absorbing material 460 is disposed in the intermediate chamber 454.

  The silencer 414 also includes a third partition plate 491 disposed in the housing 416 so that the third partition plate 491, the first wall 418, and the outer wall 422 define the sound absorption chamber 492. The second sound absorbing material 461 is disposed in the sound absorbing chamber 492.

  The silencer 414 also includes a fourth partition plate 493 that divides the first chamber 440 into an input chamber 494 and a return chamber 495. The silencer 414 further includes a return pipe 496 extending through the fourth partition plate 493 so that the input chamber 494 and the return chamber 495 are in fluid communication.

  The inlet pipe 426 extends through the outer wall 423 to the inside of the input chamber 494. Inlet pipe 426 terminates in input chamber 494. The outlet pipe 432 extends through the first wall 418, the third partition plate 491, the first partition plate 438, and the second partition plate 446. Outlet pipe 432 terminates in second chamber 448. The outlet pipe 432 includes a plurality of lateral holes 464 so that the outlet pipe 432 and the sound absorption chamber 492 are in fluid communication. Of course, the sound absorbing chamber 492 is completely sealed except for the side holes 464.

  During operation, exhaust gas and exhaust noise flow in the silencer 416 as indicated by the dashed arrows in FIG. More specifically, exhaust gas and exhaust noise travel through the inlet pipe 426 and into the input chamber 494 and enter the silencer 416. Some of the gas and noise flows into the intermediate chamber 454 through the first opening 456. The remaining gas and noise portions flow through the return pipe 496 into the return chamber 495 and then into the intermediate chamber 454 through the first opening 456. As described above, the exhaust noise is reduced when passing through the sound absorbing material 460. The gas and noise then enter the second chamber 448 through the second opening 458 and enter the outlet pipe 432. Then, substantially all the exhaust gas is discharged out of the silencer 414 through the outlet pipe 432. On the other hand, the exhaust noise is further reduced by the second sound absorbing material 461 because some of the noise goes out of the silencer 414 through the outlet pipe 432 and some enters the sound absorbing chamber 492 through the side hole 464. . Therefore, exhaust noise can be significantly reduced by the effects of both the sound absorbing materials 460 and 461.

  In short, the silencer 14, 114, 214, 314, 414 effectively exhausts the exhaust noise by allowing most of the exhaust noise to move through the sound absorbing material 60, 160, 260, 360, 460, 461. Reduce. As a result, undesired low-frequency exhaust noise and / or standing waves in the exhaust systems 12, 112, 212, 312, and 412 can be reduced.

It is a plane sectional view of an exhaust system including a silencer. FIG. 2 is a cross-sectional view of the exhaust system taken along line 2-2 of FIG. It is a graph which shows the state which reduced the exhaust noise using the silencer of FIG. 1 and FIG. It is a plane sectional view of another embodiment of an exhaust system containing a silencer. It is a graph which shows the state which reduced the exhaust noise using the silencer of FIG. 6 is a schematic diagram of another embodiment of an exhaust system including a silencer. 6 is a schematic diagram of another embodiment of an exhaust system including a silencer. 2 is a schematic diagram of another view of an exhaust system including a silencer.

Claims (13)

A muffler for a vehicle exhaust system,
A housing having an input wall and an output wall;
A first and a second partition plate having an opening, which define an input chamber and one of the input wall and the output wall in the housing, define an output chamber and the other of the input wall and the output wall; And first and second partition plates defining an intermediate chamber between the first and second partition plates;
A sound absorbing material positioned in the intermediate chamber;
An inlet pipe that penetrates the input wall, enters the housing, and terminates in the input chamber;
A muffler for a vehicle exhaust system, comprising: an outlet pipe having one end positioned in the output chamber and the other end penetrating the output wall and outside the housing.   The input chamber is adjacent to the output wall, and the inlet pipe extends from the input wall through the output chamber and the intermediate chamber and terminates in the input chamber, and the inlet pipe has a space between the inlet pipe and the intermediate chamber. The silencer according to claim 1, further comprising an opening that allows fluid communication in the chamber.   The output chamber is adjacent to the input wall, the outlet pipe extends from the output chamber through the intermediate chamber and the input chamber to the output wall, and the outlet pipe communicates fluid between the intermediate chamber and the outlet pipe. The muffler according to claim 2, further comprising an opening that enables the operation.   A flow-through pipe extending from the input chamber through the intermediate chamber to the output chamber, further comprising a flow-through pipe having a valve at one end thereof that operates so that an open area at one end thereof changes according to the pressure of the exhaust flow. The muffler according to claim 1, wherein   The silencer according to claim 1, wherein the sound absorbing material includes a roving material.   The muffler according to claim 5, wherein the roving material includes a fiber bundle of fiber glass.   The silencer according to claim 5, wherein the roving material includes a basalt wool bundle.   A solid third partition plate that defines an auxiliary sound absorbing chamber for housing the auxiliary sound absorbing material together with the housing; an outlet pipe extending through the auxiliary sound absorbing chamber and the intermediate chamber; and the outlet pipe, the auxiliary sound absorbing chamber, 2. A muffler according to claim 1, characterized in that perforations allowing fluid communication between them are drilled in the outlet pipe.   The silencer according to claim 8, wherein the sound absorbing material includes a first density roving material, and the auxiliary sound absorbing material includes a second density roving material.   The silencer according to claim 9, wherein the first density is lower than the second density.   The silencer according to claim 1, wherein the input chamber is adjacent to the input wall, and the inlet pipe passes through the input wall and terminates in the input chamber.   12. The muffler according to claim 11, wherein the output chamber is adjacent to the output wall.   The flow-through pipe further extends from the input chamber to the output chamber, and further includes a flow-through pipe having a valve at one end thereof that operates so that an open area of the one end changes according to the pressure of the exhaust flow. The muffler according to claim 12.

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