JP2009236040A - Exhaust muffler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a structure and an external shape, and to improve breaking resistance, in an exhaust muffler 1 reducing the exhaust sound of an engine. <P>SOLUTION: A resonance chamber 9 is provided adjacently to expansion chambers 7, 8 into which exhaust gas is introduced. In a delivery pipe 4 communicating with the expansion chamber 7, a partitioning wall 13 for forming a communicating passage 12 communicating a predetermined position in the delivery pipe 4 and the resonance chamber 9 is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust silencer for reducing exhaust noise of an engine mounted on, for example, a vehicle.

  In general, due to exhaust pulsation during operation of an engine mounted on a vehicle or the like, air column resonance corresponding to the passage length occurs in the exhaust system passage. Therefore, conventionally, the exhaust noise of the engine is reduced by an exhaust silencer provided in the exhaust system.

  As a conventional exhaust silencer of this type, for example, as shown in Patent Document 1, two expansion chambers are arranged in the muffler next to each other in the exhaust direction, and exhausted from the engine to the first expansion chamber located upstream in the exhaust direction. The exhaust gas is introduced and then sent to the second expansion chamber located downstream in the exhaust direction to lower the sound pressure and flow out from the second expansion chamber through the branch pipe to the outlet pipe. It is configured to reduce air column resonance generated in the tube.

  In Patent Document 1, in the configuration described above, a variable valve for adjusting the opening area is provided on the upstream side of the outlet pipe, so that the exhaust noise can be reduced according to the operating condition of the engine. .

  Further, as shown in Patent Document 2, an expansion chamber and a resonance chamber are provided in the muffler adjacent to each other in the exhaust direction, two necks having different lengths are connected to the resonance chamber and the exhaust pipe, and the inner pipe is provided in the exhaust pipe. The inner pipe is slid according to the exhaust pressure, the opening provided in the middle of the inner pipe is connected to one of the neck pipes, and the exhaust pipe communicates with the resonance chamber through the neck pipe. It is configured to make it.

In Patent Document 2, the resonance frequency of the resonance chamber can be automatically changed according to the exhaust pressure, thereby obtaining an effect of reducing the exhaust sound according to the exhaust pressure.
JP 2005-264900 A Japanese Utility Model Publication No. 4-47118

  In any of the above conventional examples, although it is possible to reduce the exhaust noise, it is pointed out that the configuration is complicated.

  For example, in the conventional example according to Patent Document 1, the U-shaped branch pipe connected to the outlet pipe is arranged inside the muffler, and there is a concern that the shape is complicated and the assembly work is troublesome.

  On the other hand, in the conventional example according to Patent Document 2, two neck pipes are attached to the outside of the muffler and the exhaust pipe, and the inner pipe is slidably housed inside the exhaust pipe. At the same time, there is a concern that the cost will increase due to complicated assembly work.

  In particular, in the conventional example according to Patent Document 2, since the two neck pipes that connect and connect the resonance chamber and the exhaust pipe are arranged outside the muffler, the outer shape becomes complicated, such as protruding outward. ing. Moreover, by disposing the two neck pipes on the outside of the muffler, and joining one end edge of the two neck pipes in a circumferential direction predetermined region of the outer peripheral surface of the exhaust pipe from the radial direction, Since the deviation of the surface temperature between the two neck pipes and the exhaust pipe becomes large and the difference in thermal expansion between the two neck pipes and the exhaust pipe becomes large, excessive stress is concentrated on the joint, and the joint may be easily damaged. There is. There is room for improvement here.

  It is an object of the present invention to achieve simplification of the configuration, simplification of the outer shape, and improvement of damage resistance in an exhaust silencer that reduces exhaust noise of an engine.

  According to the present invention, a resonance chamber is provided adjacent to an expansion chamber into which exhaust gas is introduced, and a communication path that connects a predetermined position in the extraction tube and the resonance chamber is provided in the extraction tube that communicates with the expansion chamber. A partition wall for forming is provided.

  According to this configuration, after the exhaust sound pressure is reduced by the expansion chamber, the air column resonance pressure wave due to the exhaust gas flowing out from the expansion chamber to the outlet pipe is propagated to the resonance chamber through the communication path. Since it is attenuated, air column resonance generated in the outlet pipe is reduced.

  In addition, as compared to the case where the communication path is provided as a pipe outside the case or the lead-out pipe as in the conventional example, the number of components can be reduced, and there is no extra projecting portion outward. The installation space can be made as small as possible, and an increase in the manufacturing cost of the exhaust silencer can be suppressed.

  Further, since the partition wall for forming the communication path is provided inside the outlet pipe, the deviation of the surface temperature between the outlet pipe and the partition wall can be reduced. As a result, the difference in thermal expansion between the two becomes small, so that even when the lead-out pipe and the partition wall are joined, excessive stress does not need to be concentrated at the joint, and the joint is less likely to be damaged. .

  As described above, it is possible to simplify the configuration and the outer shape of the exhaust silencer while ensuring the original exhaust noise reduction action, and to improve the damage resistance.

  The resonance chamber is set so as to have a volume (frequency) corresponding to the length of the outlet tube (wavelength of the air column resonance).

  Preferably, the partition wall is a plate-like member for partitioning and forming a spatial communication path in a necessary area of the outlet pipe, and can be joined to the outlet pipe.

  In this configuration, the specific configuration of the partition wall is specified, and it becomes clear that the specification enables simplification of the configuration, simplification of the outer shape, and improvement of breakage resistance.

  Preferably, the expansion chamber includes a first expansion chamber into which exhaust gas is introduced, and a second expansion chamber into which exhaust gas in the first expansion chamber flows and the outlet pipe is connected. The resonance chamber may be disposed adjacent to the second expansion chamber.

  In this configuration, since the plurality of expansion chambers are provided, the exhaust sound pressure is reduced stepwise. As a result, in order to sufficiently silence the air column resonance generated in the outlet tube, the adjustment range of the volume of the resonance chamber, the length of the communication path, the cross-sectional area, and the like is increased.

  According to the exhaust silencer according to the present invention, it is possible to reduce the manufacturing cost and improve the installability with a simple and simple configuration that eliminates the protruding portion to the outside while ensuring the exhaust noise reduction effect. It becomes possible to improve breakage resistance.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. 1 to 4 show an embodiment of the present invention.

  In this embodiment, an example in which the exhaust silencer according to the present invention is used in an exhaust system of an engine mounted on an automobile is given.

  First, an outline of the exhaust silencer of this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view schematically showing an embodiment of an exhaust silencer, and FIG. 2 is a cross-sectional view taken along line (2)-(2) in FIG.

  As shown in these drawings, the exhaust silencer 1 includes a muffler 2, an introduction pipe 3, and a lead-out pipe 4.

  The muffler 2 reduces exhaust noise of exhaust gas exhausted from an engine (not shown). The introduction pipe 3 introduces exhaust gas exhausted from an engine (not shown) into the muffler 2. The lead-out pipe 4 discharges exhaust gas from the muffler 2 to the atmosphere.

  Specifically, the muffler 2 is an expansion / resonance combination type, and the inside of the muffler 2 is partitioned into three adjacent spaces by providing two partition walls 5 and 6 therein.

  Of these three spaces, the space located in the middle of the exhaust direction is the first expansion chamber 7, the space located on the most upstream side is the second expansion chamber 8, and the space located on the most downstream side is the resonance chamber. It is set to 9.

  The partition wall 5 partitions the first extension chamber 7 and the second extension chamber 8, and the partition wall 6 partitions the first extension chamber 7 and the resonance chamber 9. The former partition wall 5 is provided with a large number of through holes 11, and the first extension chamber 7 and the second extension chamber 8 adjacent to each other are communicated with each other through the through holes 11.

  The resonance chamber 9 resonates with vibration of a specific frequency and reduces exhaust sound caused by the vibration. For example, in order to reduce air column resonance generated in the outlet pipe 4, the air column generated in the outlet pipe 4 Designed to have the same frequency as the resonance.

  The upstream end of the introduction pipe 3 is connected to an exhaust manifold of an engine (not shown), and the downstream end passes through the second expansion chamber 8 located on the most upstream side in the exhaust direction and passes through the first expansion chamber. 7 is open.

  The outlet pipe 4 has an upstream end that passes through the resonance chamber 9 and the first expansion chamber 7 and is opened in the second expansion chamber 8, and a downstream end that is open to the atmosphere. In the middle of the outlet pipe 4, a through hole 4 a that opens toward the resonance chamber 9 is provided.

  A partition wall 13 is provided inside the outlet pipe 4 to form a communication passage 12 that communicates a predetermined position in the outlet pipe 4 with the resonance chamber 9.

  In the partition wall 13, a through hole 14 that opens toward the inside of the outlet pipe 4 is provided at a predetermined position downstream of the communication path 12. The upstream side of the partition wall 13 is disposed so as to cover the through hole 4a of the outlet tube 4, and a predetermined position in the outlet tube 4 and the resonance chamber 9 are connected to each other through the through hole 4a and the through hole 14 of the partition wall 13. Communicated.

  As shown in FIG. 2, the partition wall 13 is made of, for example, a plate-like member having a corrugated shape in the radial cross section of the outlet tube 4. The outer peripheral edge of the partition wall 13 is slightly bent along the inner wall surface of the outlet tube 4, and the bent portion is joined to the inner wall surface of the outlet tube 4 by, for example, welding. In addition, the shape as shown in FIG. 6 shown later may be sufficient as the partition 13, and it does not specifically limit.

  By providing the partition wall 13 in the predetermined region in the outlet pipe 4 in this manner, the internal space of the predetermined region has an approximately half of its cross section serving as an exhaust gas passage and the other half serving as an interference sound propagation passage. .

  By the way, when the exhaust silencer 1 as described above is installed in the automobile, the second expansion chamber 8 and the introduction pipe 3 are on the front side of the automobile, and the resonance chamber 9 and the outlet pipe 4 are on the rear side of the automobile. Be positioned.

  Next, the operation of the exhaust silencer 1 configured as described above will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a chart showing the relationship between the length of the outlet pipe and the air column resonance frequency in the exhaust silencer of FIG. FIG. 4 is a chart for explaining the exhaust noise reduction effect of the exhaust silencer of FIG. 1, and shows the relationship between the engine speed and the sound pressure level.

  As shown by the arrow in FIG. 1, exhaust gas exhausted from an engine (not shown) is first introduced from the introduction pipe 3 into the first expansion chamber 7 to reduce the exhaust sound pressure, and then the partition wall 5 The exhaust sound pressure is further reduced by being introduced into the second expansion chamber 8 through the through hole 11.

  Thereafter, the exhaust gas in the second expansion chamber 8 is released into the atmosphere through the outlet pipe 4, and the pressure wave of the air column resonance generated with the passage of the exhaust gas in the outlet pipe 4 is Since it is propagated to the resonance chamber 9 through the communication path 12, air column resonance generated in the outlet pipe 4 due to the resonator action of the resonance chamber 9 is reduced.

  Generally, due to exhaust pulsation during engine operation, air column resonance corresponding to the tube length occurs in the lead-out tube 4, and the air column resonance is based on a frequency with the tube length as a half wavelength. .

  For reference, the frequency of the air column resonance generated in the outlet tube 4 has a correlation as shown in FIG. Therefore, the volume of the resonance chamber 9 and the dimensions and shape of the communication path 12 may be appropriately set based on the length of the outlet pipe 4.

  By the way, in general, the muffler 2 is arranged at a position where the pressure wave of the air column resonance generated between the upstream end of the exhaust manifold of the engine and the downstream end of the outlet pipe 4 reaches a peak, thereby reducing the pressure wave. It is said that it is ideal to divide, but in recent years, it is difficult to install the muffler 2 at the ideal position at the bottom of the car because of the priority given to the arrangement of the rear seats and gasoline tanks in the car. May be.

  In particular, when the muffler 2 must be installed in the middle part in the front-rear direction of the automobile, the length of the outlet pipe 4 becomes long. It is possible to obtain a sufficient exhaust noise reduction effect by appropriately designing the dimensions, shapes, etc. of 7, 8, the resonance chamber 9 and the communication passage 12.

  According to the method of such an embodiment, for example, the exhaust noise when the engine speed increases due to vehicle acceleration tends to be as shown in FIG. In the comparative example indicated by the broken line in the figure, the resonance chamber 9 is not used.

  In this comparative example, the sound pressure level reaches a peak in the middle engine speed range, and thereafter, gradually decreases in inverse proportion to the increase in engine speed. On the other hand, in the case of this embodiment, the engine speed at which the sound pressure level reaches a peak is close to the high engine speed range, and the peak of the sound pressure level decreases. Thus, in this embodiment, exhaust noise can be reduced.

  In short, in the above-described embodiment, the communication passage 12 that communicates and connects the outlet tube 4 and the resonance chamber 9 is not a pipe as in the conventional example, but is a space defined by the partition wall 13 inside the outlet tube 4. Therefore, compared with the conventional example, it is possible to reduce the number of component parts, and it is possible to suppress an increase in the manufacturing cost of the exhaust silencer 1, and it is possible to eliminate an extra protruding portion outward. Thus, the installation space for the exhaust silencer 1 can be made as small as possible.

  Further, since the partition wall 13 is provided inside the outlet tube 4, the deviation in surface temperature between the outlet tube 4 and the partition wall 13 can be reduced. As a result, the difference in thermal expansion between the two becomes small, so that excessive stress is not concentrated on the joint between the outlet tube 4 and the partition wall 13, and the joint is less likely to be damaged.

  Therefore, in this embodiment, it is possible to simplify the configuration and the outer shape of the exhaust silencer 1 while ensuring the original exhaust noise reduction action, and to improve the damage resistance. become.

  In addition, this invention is not limited only to the said embodiment, All the deformation | transformation and application included in the range equivalent to the claim and the said range are possible. Examples are given below.

  (1) In the above embodiment, an example is given in which the number of expansion chambers provided in the muffler 2 is two, but the number is arbitrary.

  (2) Another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the exhaust sound is reduced by causing the pressure wave of the exhaust gas passing through the outlet pipe 4 to interfere with the pressure wave of an appropriate frequency and phase.

  Specifically, the muffler 2 is an expansion type, and the inside of the muffler 2 is partitioned into three adjacent spaces by providing two partition walls 21 and 22 therein.

  Of these three spaces, the space located on the most downstream side in the exhaust direction is the first expansion chamber 23, the space located in the middle is the second expansion chamber 24, and the space located on the most upstream side is the third space. An extension room 25 is provided.

  The partition wall 21 partitions the first extension chamber 23 and the second extension chamber 24, and the partition wall 22 partitions the second extension chamber 24 and the third extension chamber 25. Both partition walls 21 and 22 are provided with a large number of through holes 26 and 27, respectively, and adjacent rooms communicate with each other through the through holes 26 and 27.

  The upstream end of the introduction pipe 3 is connected to an exhaust manifold (not shown) of the engine, and the downstream end passes through the third expansion chamber 25 and the second expansion chamber 24 and opens to the first expansion chamber 23. It has come to be.

  The outlet pipe 4 has an upstream end that passes through the second expansion chamber 24 and the third expansion chamber 25 and is opened in the first expansion chamber 23, and a downstream end that is open to the atmosphere. In the middle of the outlet pipe 4, a through hole 4 a that opens toward the inside of the first expansion chamber 23 is provided.

  A partition wall 29 is provided inside the outlet pipe 4 to form a communication path 28 that communicates a predetermined position in the outlet pipe 4 with the first expansion chamber 23.

  In the partition wall 29, a through hole 30 that opens toward the inside of the outlet pipe 4 is provided at a predetermined position downstream of the communication path 28. The upstream side of the partition wall 29 is disposed so as to cover the through hole 4 a of the outlet pipe 4, and a predetermined position in the outlet pipe 4 and the first expansion chamber 23 through the through hole 4 a and the through hole 30 of the partition wall 29. And communicated with each other.

  As shown in FIG. 6, the partition wall 29 is made of, for example, a flat plate member. The outer peripheral edge of the partition wall 29 is slightly bent along the inner wall surface of the outlet tube 4, and the bent portion is joined to the inner wall surface of the outlet tube 4 by, for example, welding. The partition wall 29 may have a shape as shown in FIG. 2 and is not particularly limited.

  Next, the operation of the exhaust silencer 1 configured as described above will be described.

  Exhaust gas discharged from an engine (not shown) is first introduced from the introduction pipe 3 into the first expansion chamber 23 as shown by an arrow in FIG. 5, and then passed through the through hole 26 of the partition wall 21 to be second. By sequentially introducing the expansion chamber 24 and the third expansion chamber 25 through the through hole 27 of the partition wall 22, the exhaust sound pressure is gradually reduced.

  Thereafter, the exhaust gas in the third expansion chamber 25 is released to the atmosphere through the outlet pipe 4, and a part of the exhaust gas introduced from the introduction pipe 3 into the first expansion chamber 23 is communicated with the communication path 28. Through this, the lead-out pipe 4 is introduced in a short circuit.

  In other words, the exhaust noise propagated to the lead-out pipe 4 through the communication path 28 interferes with the air column resonance generated by the passage of the exhaust gas introduced from the third expansion chamber 25 into the lead-out pipe 4. Will be. That is, since the exhaust sound having a different frequency and phase is made to interfere with the air column resonance sound, the air column resonance sound generated in the outlet tube 4 is reduced.

  Here, the frequency and phase of the exhaust sound propagated from the communication passage 28 to the outlet pipe 4 are air columns generated as the exhaust gas introduced into the outlet pipe 4 through the first to third expansion chambers 23 to 25 passes. In consideration of the frequency and phase of the resonance sound, the frequency is appropriately set so as to obtain a target exhaust noise reduction effect. For example, the frequency of the exhaust sound that interferes with the air column resonance sound is preferably ½ wavelength with respect to the frequency of the air column resonance sound. Based on this, the size and shape of each part of the muffler 2 and the ratio of the cross-sectional area of each flow path (see FIG. 2) for the region where the communication path 28 exists in the outlet pipe 4 are appropriately designed. ing.

  According to the method of such an embodiment, for example, the exhaust noise when the engine speed increases due to vehicle acceleration tends to be as shown in FIG. In the comparative example indicated by the broken line in the figure, it is assumed that interference is not performed as in the embodiment.

  In this comparative example, the sound pressure level reaches a peak in the middle engine speed range, and thereafter, gradually decreases in inverse proportion to the increase in engine speed. On the other hand, in the case of this embodiment, the sound pressure level from the low engine speed range to the medium engine speed range can be lowered, and the engine speed can be increased from the medium engine speed range to the high engine speed range. Accordingly, it is preferable that the sound pressure level can be gradually increased. Thus, in this embodiment, exhaust noise can be reduced.

  In short, in this embodiment, the communication passage 28 that communicates and connects the outlet pipe 4 and the first expansion chamber 23 is defined by a partition wall 29 inside the outlet pipe 4 without using a pipe as in the conventional example. Therefore, it is possible to reduce the number of components compared to the conventional example and to suppress an increase in the manufacturing cost of the exhaust silencer 1, and to eliminate an excessive protruding portion outward. Thus, the installation space for the exhaust silencer 1 can be made as small as possible.

  Further, since the partition wall 29 is provided inside the outlet pipe 4, the deviation in surface temperature between the outlet pipe 4 and the partition wall 29 can be reduced. As a result, the difference in thermal expansion between the two is reduced, so that excessive stress is not concentrated on the joint between the outlet tube 4 and the partition wall 29, and the joint is less likely to be damaged.

  Therefore, in this embodiment, it is possible to simplify the configuration and the outer shape of the exhaust silencer 1 while ensuring the original exhaust noise reduction action, and to improve the damage resistance. become.

It is sectional drawing which shows typically one Embodiment of the exhaust silencer which concerns on this invention. It is an arrow view of the (2)-(2) line cross section of FIG. It is a chart which shows the relationship between the length of the outlet tube in the exhaust silencer of FIG. 1, and an air column resonance frequency. FIG. 2 is a chart for explaining the exhaust noise reduction action of the exhaust silencer of FIG. 1 and shows the relationship between the engine speed and the sound pressure level. It is sectional drawing which shows typically the other example of the exhaust silencer which concerns on this invention. FIG. 6 is a cross sectional view taken along line (6)-(6) in FIG. 5. FIG. 5 is a chart for explaining the exhaust noise reduction effect of the exhaust silencer of FIG. 5 and shows the relationship between the engine speed and the sound pressure level.

Explanation of symbols

1 Exhaust silencer
2 Muffler
3 Introduction pipe
4 Outlet pipe
4a Lead-through hole
5 First extension room
6 Second expansion room
7 Resonance chamber 12 Communication passage 13 Bulkhead 14 Bulkhead passage

Claims (3)

  A resonance chamber is provided adjacent to the expansion chamber into which the exhaust gas is introduced, and a communication path for communicating a predetermined position in the discharge tube with the resonance chamber is formed in the discharge tube communicating with the expansion chamber. An exhaust silencer characterized in that a partition wall is provided. The exhaust silencer according to claim 1,
The exhaust silencer according to claim 1, wherein the partition wall is a plate-like member for partitioning and forming a spatial communication path in a necessary area of the outlet pipe, and is joined to the outlet pipe. The exhaust silencer according to claim 1 or 2,
The expansion chamber includes a first expansion chamber into which exhaust gas is introduced, and a second expansion chamber into which the exhaust gas in the first expansion chamber is introduced and the outlet pipe is connected in communication. An exhaust silencer, wherein the resonance chamber is disposed adjacent to the chamber.

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