JP6162407B2 - Silencer - Google Patents

Description

  The present invention relates to a silencer for suppressing exhaust noise.

  The exhaust system for automobiles suppresses exhaust noise by a silencer provided in the exhaust passage. For example, low-frequency air column resonance generated in a long tubular section may cause deterioration of exhaust noise, so measures such as reducing the air column resonance by providing a sub-muffler in series with the main muffler. Has been taken. Patent Document 1 describes a configuration in which a side branch type resonance silencer is provided between a main muffler and a sub muffler.

JP 2005-105918 A

  Incidentally, as a resonance silencer, a Helmholtz resonance silencer is known in addition to the side branch resonance silencer described above. However, since the Helmholtz type silencer is realized by a structure that reaches a resonance chamber having a large volume via an elongated communication path, there is a problem that the structure becomes complicated.

  The present invention has been made in view of these problems, and an object thereof is to provide a silencer that realizes a Helmholtz resonance system with a simple structure.

  The silencer of the present invention includes a first tubular member that forms an exhaust passage of an internal combustion engine, and a second tubular member that is connected to the first tubular member and forms the exhaust passage together with the first tubular member. A tubular member, and a double tube portion is formed in which an end portion of the first tubular member is inserted inwardly from an end portion of the second tubular member, and a distal end portion of the second tubular member is The portion that is joined to the outer peripheral surface of the first tubular member and that forms the double tube portion of the second tubular member includes a first portion near the tip of the first tubular member, and the first tubular member. A second portion having a diameter larger than that of the first portion, the portion being close to the tip of the two tubular members, and between the first tubular member and the second portion Includes a resonance chamber, and the exhaust passage and the resonance chamber are provided between the first tubular member and the first portion. The communication passage is formed to be passing, Helmholtz resonance system is constituted by the resonance chamber and the communicating path.

  According to such a configuration, exhaust noise can be suppressed at the connection portion between the first tubular member and the second tubular member. In addition, a double tube portion is formed by two tubular members forming the exhaust flow path, and a resonance chamber and a communication path of the Helmholtz resonance system are formed using the double tube portion. Can be realized with a simple structure.

  In the above configuration, the communication path is provided with a spacer for preventing contact between the first tubular member and the second tubular member, and the spacer does not block the communication path. In addition, the air passage may be secured on the outer periphery of the first tubular member. According to such a configuration, the effect of suppressing the exhaust noise can be enhanced as much as the communication path is less likely to be blocked.

  In the above configuration, each of the first tubular member and the second tubular member may be formed of a single component. According to such a configuration, it is not necessary to separately use a dedicated component for configuring the Helmholtz resonance system, so that space saving and cost reduction can be achieved.

  In addition to the silencer described above, the present invention can be realized in various forms such as an exhaust system including a silencer and an exhaust silencer method.

It is a top view of the exhaust system of an embodiment. It is II-II sectional drawing of FIG. (A) is an exploded perspective view of the silencer, (B) is a transparent perspective view of the silencer. It is IV-IV sectional drawing of FIG.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
An exhaust system 1 shown in FIG. 1 forms an exhaust passage that serves as a passage for exhaust gas discharged from an internal combustion engine of an automobile. The exhaust system 1 is configured around a tubular channel member 2 that forms a long exhaust channel having a long actual length, and a plurality of components 3, 4, and 5 are arranged along the channel member 2 (exhaust channel). They are arranged in series. Specifically, the exhaust system 1 includes a catalytic converter 3, a sub muffler 4, and a main muffler 5 in order from the upstream side (the left side in FIG. 1) of the exhaust flow path.

  The portion of the flow path member 2 that connects the sub muffler 4 and the main muffler 5 is formed at the first tubular member 10 that forms the exhaust flow path downstream of the sub muffler 4 and the downstream end of the first tubular member 10. And a second tubular member 20 that forms an exhaust passage upstream of the main muffler 5.

  As shown in FIGS. 2, 3A and 3B, the first tubular member 10 is a member formed by processing a circular pipe component having an outer diameter R1 (for example, 60.5 mm). Consists of a single part. Specifically, the first tubular member 10 has an outer diameter at an end portion on the downstream side (right side in FIG. 2), specifically, a portion having a length L1 from the distal end of the circular pipe component having an outer diameter R1. The member is reduced in diameter to an outer diameter R2 (for example, 54.7 mm) smaller than R1. In the following description, a portion of the first tubular member 10 having a length L1 from the tip is referred to as a “reduced diameter portion 11”, and the remaining portion is referred to as a “main body portion 12”.

  Similar to the first tubular member 10, the second tubular member 20 is a member formed by processing a circular pipe component having an outer diameter R1 and, like the first tubular member 10, is composed of a single component. Has been. Specifically, the second tubular member 20 has an outer diameter R1 having an end on the upstream side (left side in FIG. 2), specifically, a portion having a length L2 from the tip. The member is expanded to an outer diameter larger than R1. Specifically, the outer diameter gradually increases from the position of the length L2 from the tip toward the tip side, and the largest outer diameter (for example, 120 mm) at the position of the length L3 (L3 <L2) from the tip. Become. Then, the outer diameter gradually decreases from the position of the length L4 from the tip (L4 <L3) toward the tip. Such a shape is realized, for example, by performing a process of expanding the diameter L2 from the tip and then performing a process of reducing the length L4 from the tip. In the following description, the portion of the second tubular member 20 having a length L2 from the distal end is referred to as “expanded diameter portion 21”, and the remaining portion is referred to as “main body portion 22”.

The downstream end portion of the first tubular member 10, specifically, the entire reduced diameter portion 11 and a part of the main body portion 12 are the upstream end portion of the second tubular member 20 (the distal end portion of the enlarged diameter portion 21). 23) to the inside of the second tubular member 20 so that the central axes thereof coincide with each other. As a result, the first tubular member 10 is connected to the inner tube and the second tubular member 20 is connected to the connecting portion between the first tubular member 10 and the second tubular member 20 (joint location described below and a portion in the vicinity thereof). A double tube portion (a portion where the first tubular member 10 and the second tubular member 20 overlap) is formed. As will be described below, the connecting portion between the first tubular member 10 and the second tubular member 20 functions as a Helmholtz resonance silencer 30.

  That is, the second tubular member 20, specifically, the distal end portion 23 of the enlarged diameter portion 21 is joined to the outer peripheral surface of the first tubular member 10, specifically the main body portion 12 (in this embodiment, all-around welding). ) As a result, a dead-end space communicating with the exhaust flow path is formed between the first tubular member 10 and the second tubular member 20 in the double tube portion. Specifically, a resonance chamber 31 having a large volume is formed between the main body portion 12 of the first tubular member 10 and the enlarged diameter portion 21 of the second tubular member 20. In other words, a volume necessary for the resonance chamber 31 is ensured by the enlarged diameter portion 21 of the second tubular member 20. Further, a space between the reduced diameter portion 11 of the first tubular member 10 and the main body portion 22 of the second tubular member 20 is a space in which the cross-sectional area perpendicular to the axial direction is smaller than that of the resonance chamber 31, A communication path 32 that connects the exhaust passage and the resonance chamber 31 is formed. The resonance chamber 31 and the communication path 32 are designed in a shape that constitutes a Helmholtz resonance system.

  The communication path 32 is provided with a wire mesh 40 that is a metal buffer member. The wire mesh 40 functions as a spacer for preventing contact between the first tubular member 10 and the second tubular member 20. The wire mesh 40 also has a function of reducing the stress due to the difference in thermal shrinkage between the first tubular member 10 and the second tubular member 20. The outer diameter of the wire mesh 40 is equal to or smaller than the outer diameter R1 of the main body 12 of the first tubular member 10.

  However, if the communication path 32 is blocked by the wire mesh 40, the excitation force of the sound pressure that causes the resonance phenomenon is hardly transmitted to the resonance chamber 31. Therefore, the wire mesh 40 is disposed so that an air passage is secured on the outer periphery of the first tubular member 10. Specifically, as shown in FIG. 4, in the present embodiment, along the outer peripheral surface of the first tubular member 10, a part of the entire outer periphery of the first tubular member 10 (range of 360 degrees). A plurality of arcuate (three in this example) wire meshes 40 are arranged. The three wire meshes 40 have a length that is less than the entire outer circumference of the first tubular member 10 even if they are all combined, and the three wire meshes 40 are arranged in the axial direction of the first tubular member 10. They are shifted (at different positions in the axial direction) (see FIG. 2). Therefore, a good ventilation path is secured on the outer periphery of the first tubular member 10.

  The silencer 30 is designed so that the resonance frequency matches the N-order mode (N is a natural number, 1 in the present embodiment) of the air column resonance frequency of the pipe. Are arranged so that the tip of the position is the position of the maximum sound pressure in the Nth order mode.

According to the embodiment detailed above, the following effects can be obtained.
[A1] The silencer 30 is connected to the first tubular member 10 that forms the exhaust passage of the internal combustion engine, and the second tubular member 10 that forms the exhaust passage together with the first tubular member 10. The tubular member 20 is provided. At the connection portion between the first tubular member 10 and the second tubular member 20, a double tube portion in which the end portion of the first tubular member 10 is inserted inward from the distal end portion 23 of the second tubular member 20. The tip 23 of the second tubular member 20 is joined to the outer peripheral surface of the first tubular member 10. The portions forming the double tube portion in the second tubular member 20 are the main body portion 22 near the tip of the first tubular member 10, and the portion near the tip of the second tubular member 20. And a diameter-expanded portion 21 whose diameter is increased in comparison. A resonance chamber 31 is formed between the first tubular member 10 and the enlarged diameter portion 21, and the exhaust passage and the resonance chamber 31 are communicated between the first tubular member 10 and the main body portion 22. A communication path 32 is formed, and the resonance chamber 31 and the communication path 32 constitute a Helmholtz resonance system.

  Therefore, according to the present embodiment, air column resonance noise can be suppressed at the connection portion between the first tubular member 10 and the second tubular member 20, and as a result, exhaust noise can be suppressed. . In addition, a double tube portion is formed by the first tubular member 10 and the second tubular member 20 forming the exhaust flow path, and the Helmholtz resonance system resonance chamber 31 and the communication passage are formed using the double tube portion. Since 32 is formed, the Helmholtz resonance system can be realized with a simple structure. In particular, since the Helmholtz resonance system is employed, the silencing effect can be enhanced by increasing the volume of the resonance chamber 31. Although it is possible to form a through hole in the first tubular member 10 and make this through hole function as a communication path of the Helmholtz type resonance system, in such a structure, the length of the communication path is equal to the plate thickness. However, it is difficult to obtain a sufficient effect. In this respect, in the present embodiment, a structure having a long communication path is realized, and the noise suppression effect can be enhanced.

  [A2] The communication path 32 is provided with a wire mesh 40 for preventing contact between the first tubular member 10 and the second tubular member 20. The wire mesh 40 is disposed so that a ventilation path is secured on the outer periphery of the first tubular member 10 so that the communication path 32 is not blocked. Therefore, according to the present embodiment, the effect of suppressing the exhaust noise can be enhanced as much as the communication path 32 is less likely to be blocked.

  [A3] Each of the first tubular member 10 and the second tubular member 20 is formed of a single component. Therefore, according to the present embodiment, it is not necessary to separately use a dedicated component for configuring the Helmholtz resonance system, so that space saving, cost reduction, and the like can be achieved. That is, in the configuration in which a dedicated part for forming the silencer (resonance chamber and communication path) is added to the part forming the exhaust flow path, the structure is complicated and the size is easily increased, and the number of parts is large. Since the number of joints (welding) increases, the cost tends to increase. On the other hand, the silencer 30 of the present embodiment is composed of the first tubular member 10 and the second tubular member 20 that form the exhaust flow path, and since there is one joining (welding) location, There is an advantage that it is easy to save space and cost. In addition, since it is composed of a tubular member, it can be bent and has the advantage of being easily adaptable to the layout of the exhaust system 1.

  [A4] The silencer 30 is designed so that the resonance frequency matches the Nth order mode of the air column resonance frequency of the pipe, and the tip of the first tubular member 10 is positioned at the position of the maximum sound pressure of the Nth order mode. It is arranged to be. Therefore, according to the present embodiment, it is possible to obtain the maximum reduction in the mode matched to the resonance frequency, and also suppress the air column resonance sound by reducing the sound pressure with a constant capacity in other modes. can do.

  [A5] Since the reduced diameter portion 11 is formed in the first tubular member 10 and the wire mesh 40 having an outer diameter equal to or less than the outer diameter R1 of the main body portion 12 is used, the first in a state where the wire mesh 40 is attached. The tubular member 10 can be easily inserted into the second tubular member 20. Therefore, according to this embodiment, the assembly of the first tubular member 10 and the second tubular member 20 can be facilitated.

As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment.
[B1] The wire mesh 40 shown in the above embodiment is an example, and the present invention is not limited to this. For example, the number of wire meshes 40 may be one, or two or more. Further, the position where the wire mesh 40 is arranged is not particularly limited. Specifically, for example, two C-shaped wire meshes having a shape in which a ring is divided in half may be shifted in the axial direction of the first tubular member 10. Further, a member other than the wire mesh 40 may be used as the spacer. Further, at least one of the first tubular member 10 and the second tubular member 20 may be processed (for example, a convex portion is formed) to form a spacer. Moreover, it is good also as a structure which does not have a spacer.

  [B2] The first tubular member 10 may be formed of a plurality of parts. For example, if a circular pipe component having an outer diameter R2 and a circular pipe component having an outer diameter R1 are used, the range of diameter reduction processing can be reduced, or the diameter reduction processing itself can be eliminated. Similarly, the second tubular member 20 may be formed of a plurality of parts.

  [B3] The first tubular member 10 may not have the reduced diameter portion 11. For example, the distal end portion 23 of the second tubular member 20 may be reduced in diameter after the first tubular member 10 with the wire mesh 40 mounted thereon is inserted into the second tubular member 20.

  [B4] In the above embodiment, the first tubular member 10 and the second tubular member 20 are formed using circular pipe components having the same outer diameter, but the present invention is not limited to this. For example, as the second tubular member 20, a circular pipe component having an outer diameter larger than that of the first tubular member 10 may be used. Moreover, the 1st tubular member 10 and the 2nd tubular member 20 may be formed using components (for example, a tubular member whose cross section is an ellipse or a polygon) other than a circular pipe component.

  [B5] The resonance chamber 31 shown in the above embodiment is an example, and the present invention is not limited to this. For example, in the above embodiment, the resonance chamber 31 is formed by the enlarged-diameter portion 21 swelled in a substantially trapezoidal shape when viewed from the side (viewed from a direction perpendicular to the axial direction). For example, the resonance chamber may be formed by an enlarged diameter portion that swells in a substantially triangular shape or a substantially rectangular shape.

  [B6] In the above embodiment, the configuration in which the silencer 30 is disposed in the exhaust flow path connecting the sub muffler 4 and the main muffler 5 is illustrated, but the present invention is not limited to this. Further, the configuration of the exhaust system as a premise is not limited to the above embodiment, and for example, a configuration without a sub-muffler may be employed. Also, the upstream / downstream positional relationship between the first tubular member (inner tube of the double tube portion) and the second tubular member (outer tube of the double tube portion) may be the reverse of the above embodiment. Good. That is, the second tubular member may be disposed on the upstream side of the exhaust flow path, and the first tubular member may be disposed on the downstream side thereof.

  [B7] Each component of the present invention is conceptual and is not limited to the above embodiment. For example, the functions of one component may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function.

  DESCRIPTION OF SYMBOLS 1 ... Exhaust system, 2 ... Flow path member, 3 ... Catalytic converter, 4 ... Sub muffler, 5 ... Main muffler, 10 ... 1st tubular member, 11 ... Reduced diameter part, 12 ... Main-body part, 20 ... 2nd tubular Member, 21 ... enlarged diameter part, 22 ... main body part, 23 ... tip part, 30 ... silencer, 31 ... resonance chamber, 32 ... communication path, 40 ... wire mesh

Claims (6)

A first tubular member forming an exhaust passage of the internal combustion engine;
A second tubular member connected to the first tubular member and forming the exhaust passage together with the first tubular member;
A plurality of spacers;
With
A double tube portion is formed in which an end portion of the first tubular member is inserted inward from an end portion of the second tubular member;
The distal end portion of the second tubular member is joined to the outer peripheral surface of the first tubular member,
The portion of the second tubular member forming the double tube portion is a first portion near the tip of the first tubular member and a portion near the tip of the second tubular member, A second portion whose diameter is enlarged compared to the first portion,
A resonance chamber is formed between the first tubular member and the second portion,
Between the first tubular member and the first portion, a communication path that connects the exhaust flow path and the resonance chamber is formed,
A Helmholtz resonance system is constituted by the resonance chamber and the communication path,
The plurality of spacers are arranged along the outer peripheral surface of the first tubular member in a part of the entire outer periphery of the first tubular member in the communication path, and even if all of them are combined, the first The length is less than the entire outer circumference of the tubular member, and they are arranged so as not to overlap each other when viewed from the axial direction of the first tubular member, and at different positions in the axial direction of the first tubular member. A muffler characterized by The muffler according to claim 1,
The plurality of spacers are provided to prevent contact between the first tubular member and the second tubular member, and an air passage is provided on an outer periphery of the first tubular member so that the communication passage is not blocked. A silencer characterized by being arranged so as to be secured. The muffler according to claim 1 or 2,
Each of the first tubular member and the second tubular member is formed of a single component. A muffler according to any one of claims 1 to 3, wherein
The second tubular member is connected to a downstream end portion of the first tubular member. A silencer, wherein: The muffler according to claim 4,
The first tubular member has a diameter-reduced portion of a predetermined length from the downstream end of the circular pipe component, a reduced diameter portion that is a reduced diameter portion, and a main body that is not reduced in diameter. And a member having
The second tubular member includes a main body that is a diameter-expanded portion in which a portion having a predetermined length is expanded from a tip on the upstream side of the circular pipe component, and a portion that is not expanded. And a member having
In the first tubular member, the downstream end portion including the whole of the reduced diameter portion and a part of the main body portion is inserted inside the second tubular member,
The resonance chamber which is a dead end space communicating with the exhaust flow path is formed between the main body portion of the first tubular member and the enlarged diameter portion of the second tubular member,
A space between the reduced diameter portion of the first tubular member and the main body portion of the second tubular member is a space having a smaller cross-sectional area perpendicular to the axial direction than the resonance chamber, and the exhaust flow The muffler is characterized in that the communication path, which is a space communicating the path and the resonance chamber, is formed. A muffler according to any one of claims 1 to 5,
The outer diameter of the second portion gradually increases from the position of the length L2 with the tip as the base point toward the tip side, and is the most at the position of the length L3 with the tip as the base point (L3 <L2). A muffler characterized by having a large outer diameter and a shape in which the outer diameter gradually decreases from the position of the length L4 (L4 <L3) starting from the tip toward the tip.

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