JP2006207548A - Exhaust device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust device for a vehicle capable of accelerating activation of a catalyst from a cold state without increasing the number of parts even in the case of arranging the catalyst in a muffler while allowing the arrangement of a plurality of communicating pipes by effectively using a limited partition wall surface. <P>SOLUTION: The exhaust device for the vehicle is provided with partition walls 61, 62 and the plurality of communicating pipes 63, 64, 65 in the muffler 26 connected to an exhaust pipe extending from an engine, wherein the partition walls 61, 62 partition the inside of the muffler 26 into a plurality of expansion chambers X, Y, Z, and the plurality of communicating pipes 63, 64, 65 pass through the partition walls 61, 62. Out of the plurality of communicating pipes 63, 64, 65, the communicating pipe 65 is disposed passing through the inside of the communicating pipe 64. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust device for a vehicle including a partition wall and a communication pipe in a muffler connected to an exhaust pipe extending from an engine.

In general, inside a muffler connected to an exhaust pipe extending from the engine, a partition wall that divides the inside of the muffler into a plurality of expansion chambers, and the expansion chambers communicate with each other between the expansion chambers and the space outside the muffler. 2. Description of the Related Art A motorcycle exhaust system including a plurality of communication pipes is known.
In this type of vehicle exhaust system, in order to reverse the flow of exhaust gas in the muffler and enhance the silencing effect, a type in which a plurality of communication pipes are arranged at regular intervals on the partition wall separating the expansion chambers is known. (For example, refer to Patent Document 1).
Further, in the technique of the above-mentioned patent document, a U-shaped communication pipe connected to the exhaust pipe is arranged in the muffler, and a catalyst body is arranged close to the outlet portion of the U-shaped communication pipe, and the activity of the catalyst In order to promote the conversion, there has been proposed an arrangement in which a heat transfer component for transmitting the heat of the upstream portion of the U-shaped communication pipe to the outer peripheral portion of the catalyst body is arranged.
JP 2002-195027 A

However, in the conventional exhaust system, a plurality of communication pipes are arranged on the partition wall at regular intervals, so that when the number of passes increases, the number of communication pipes penetrating the partition wall increases and the communication pipe can be arranged freely. The degree may be limited. For example, in the case of an elliptical partition wall, when the number of penetrating communication pipes is increased to 3 or more, it is difficult to arrange the communication pipes at regular intervals as compared to a perfect circular partition wall.
In addition, when a catalyst body is disposed in the muffler, the number of parts increases if a heat transfer component that conducts heat is disposed in the catalyst body. Furthermore, when the heat transfer component is arranged, heat unevenness occurs between the contact portion and the non-contact portion of the heat transfer component, and it may take time until the entire catalyst body is activated. .

  Accordingly, an object of the present invention is to provide a vehicle exhaust device that can solve the above-described problems of the prior art and can arrange a plurality of communication pipes by effectively using a limited partition wall surface. . It is another object of the present invention to provide an exhaust device for a vehicle that can promote activation of a catalyst from a cold state without increasing the number of parts even when the catalyst is arranged in a muffler.

In order to solve the above-described problems, the present invention provides a vehicle including a muffler connected to an exhaust pipe extending from an engine, a partition wall that partitions the muffler into a plurality of expansion chambers, and a plurality of communication pipes that pass through the partition wall. In the exhaust apparatus, the other communication pipes are disposed inside the one communication pipe among the plurality of communication pipes.
According to the present invention, among the plurality of communication pipes penetrating the partition walls, the other communication pipes are arranged inside the one communication pipe so that the plurality of communication pipes are arranged at regular intervals and arranged in a partition wall. Compared with the case of arranging in the above, the space for arranging the communication pipes can be reduced, and a plurality of communication pipes can be arranged by effectively using the limited partition wall surface. improves.

  In this case, the one communication pipe may communicate between adjacent expansion chambers, and the other communication pipe may pass through another partition across at least one of the adjacent expansion chambers. . According to this configuration, a three-pass structure effective for sound reduction can be realized with a simple pipe arrangement. Further, the other communication pipe is a tail pipe that discharges the exhaust gas to the outside of the muffler, so that options for the arrangement of the tail pipe can be expanded.

  Further, an upstream opening end of the other communication pipe opens upstream from the opening end of the one communication pipe, and a catalyst body is disposed between the other communication pipe and the one communication pipe. May be. According to this configuration, the catalyst body is warmed by heat radiation from the other communication pipe through which the exhaust gas upstream of the exhaust gas passing through the catalyst body passes, so that heat from the exhaust pipe is transmitted to the catalyst body. Even if no heat transfer component is provided, the catalyst body can be warmed by heat radiation from other communication pipes, and the exhaust gas can be exhausted as compared with the case where the catalyst body is arranged immediately after the extension pipe of the exhaust pipe. The activation of the catalyst body can be promoted without increasing the resistance. Further, in this configuration, by using the other communication pipe as an extension pipe of the exhaust pipe, the catalyst body can be warmed by heat radiation from the extension pipe heated by the high-temperature exhaust gas. Is more promoted.

In the present invention, among the plurality of communication pipes penetrating the partition wall dividing the inside of the muffler into a plurality of expansion chambers, the other communication pipe is disposed inside the one communication pipe, so that the limited partition wall surface A plurality of communication pipes can be arranged effectively and the degree of freedom of arrangement of the communication pipes is improved.
Further, the upstream end of the other communication pipe is opened upstream from the open end of the one communication pipe, and the catalyst body is disposed between the other communication pipe and the one communication pipe, thereby providing a catalyst body. Without the need for heat transfer parts to transfer heat from the exhaust pipe, the catalyst body can be warmed by heat dissipation from other communication pipes, and the catalyst body is placed immediately after the extension pipe of the exhaust pipe. The activation of the catalyst body can be promoted without increasing the exhaust resistance as compared with the case of doing so. In this case, by using another communication pipe as an extension pipe of the exhaust pipe, the catalyst body can be warmed by heat radiation from the extension pipe heated by the high-temperature exhaust gas, and the activation of the catalyst body is further promoted. The

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description, descriptions of directions such as front and rear and left and right are for the vehicle body.
FIG. 1 shows a side view of the overall configuration of the motorcycle according to the present embodiment. The motorcycle 1 includes a body frame 2, a pair of left and right front forks 3 rotatably supported on a front end portion of the body frame 2, and attached to the upper end portions of the front forks 3 so as to be placed on the upper portion of the front portion of the vehicle body. A pair of left and right steering bar handles 4 arranged, a front wheel 5 rotatably supported by the front fork 3, an engine 6 supported by the vehicle body frame 2, and a radiator 7 disposed in front of the engine 6; A rear fork 8 that is swingably supported in the vertical direction by the rear end of the engine 6 and the vehicle body frame 2, a rear wheel 9 that is rotatably supported by the rear end portion of the rear fork 8, and the vehicle body frame 2. A fuel tank 10 disposed at the top, a passenger seat 11 on which a driver is disposed behind the fuel tank 10 and a pillion seat 12 on which the passenger is seated. Eteori, substantially the entire vehicle body front is covered by the front cowl 15. The pillion seat 12 is provided on a rear cowl 13 disposed on the rear side of the riding seat 11.

  The vehicle body frame 2 includes a head pipe 16 at the front end, a front engine hanger 17a and a rear engine hanger 17b that extend rearward and obliquely downward from the head pipe 16 to the left and right, and extend downwardly forward and backward. A pair of left and right main frames 17 provided, a pair of left and right connecting plates 19 connected to the rear upper side of the main frame 17, and a pair of left and right connecting to the main frames 17 and the connecting plates 19 and extending diagonally upward rearward. And a seat rail 18. The seat rail 18 is connected to the connecting plate 19 and extends rearward and obliquely upward, and the left and right upper pipes 18a are connected to the connecting portion 20 at the rear end of the main frame 17 and extend leftward and obliquely upward. The upper pipe 18a and the lower pipe 18b are welded to each other at their rear ends. The front end portion of the rear cowl 13 is connected to the connecting portion 20 of the main frame 17.

  The engine 6 includes a cylinder block 22 having a cylinder head 21 and a crankcase 23 continuously provided below the cylinder block 22, and four cylinders (cylinders) are provided in the cylinder block 22 in the left-right direction. This is a parallel 4-cylinder 4-cycle engine arranged in parallel. In the engine 6, the cylinder block 22 is tilted slightly forward, the cylinder block 22 is placed on the front engine hanger 17 a of the main frame 17, and the rear upper end of the crankcase 23 is located on the rear side of the rear end of the main frame 17. It is supported by the vehicle body frame 2 by being bolted to the engine hanger 17b.

  Further, an exhaust pipe 25 (only one is shown in FIG. 1) is connected to the front part of the cylinder block 22 for every four cylinders, and the four exhaust pipes 25 are connected end portions to the cylinder block 22. The exhaust pipe 25 extends downward from the engine 25a and is aligned with the exhaust pipes 25 at the lower side of the engine 6, and further extends rearward along the lower surface of the crankcase 23. One collective exhaust pipe 25b extends rearward of the crankcase 23. It is summarized in. The collective exhaust pipe 25b is disposed along the right side of the rear wheel 9 while rising diagonally right rearward, and a true cylindrical muffler 26 is connected to the rear end portion thereof. A muffler band 26a is attached to the muffler 26, and the muffler band 26a is fixed to the lower pipe 18b of the seat rail 18 via a muffler stay 26b.

  The rear fork 8 has a pair of left and right fork portions 31 extending rearward from a base portion 30 at the front end thereof, and the base portion 30 is pivotally supported by a pivot 6A provided at the rear end portion of the engine 6. The pivot 6A can swing in the vertical direction. A rear cushion unit 32 is interposed between the base 30 of the rear fork 8 and the rear end of the main frame 17, thereby relaxing and absorbing vibrations received by the rear wheel 9 from the road surface. A front rear fender 33 that covers the upper front part of the rear wheel 9 is attached to the upper part of the fork part 31, and an upper rear fender 34 that covers the middle upper part of the rear wheel is also attached to the lower part of the rear cowl 13. A rear rear fender 35 covering the rear upper part of the rear wheel is also attached to the rear part of the upper rear fender 34.

  In addition, a pair of left and right front winkers 36 are attached to the front cowl 15, and a pair of left and right rear winkers 37 are attached to a boundary portion between the upper rear fender 34 and the rear rear fender 35. Further, the tail lamp unit 40 is disposed inside a portion surrounded by the rear end portion of the rear cowl 13 and the rear end portion of the upper rear fender 34 attached to the lower side of the rear cowl 13.

  The rear cowl 13 covers the outside of the seat rail 18 composed of the upper pipe 18a on the upper side and the lower pipe 18b on the lower side, and particularly covers the lower pipe 18b. That is, even when the motorcycle is viewed from the side, the lower pipe 18b cannot be seen at all. The rear end of the rear cowl 13 is connected to the connecting portion 20 of the main frame 17.

Now, in this embodiment, as shown in FIG. 2, the muffler 26 has a cylindrical main body 60, and the inside of the main body 60 is divided into three parts via a first circular partition wall 61 and a second partition wall 62. It is partitioned into expansion chambers X, Y, and Z. Hereinafter, the expansion chamber X is referred to as a first expansion chamber, the expansion chamber Z is referred to as a second expansion chamber, and the expansion chamber Y is referred to as a third expansion chamber.
An extension pipe 25c of the collective exhaust pipe 25b is fixed through the front end wall (partition wall) 63 of the muffler 26, and an outlet 25d of the extension pipe 25c communicates with the first expansion chamber X.
A communication pipe 63 is fixed to the first partition wall 61 at a position slightly deviated from the center of the first partition wall 61, and the front opening end 63 a of the communication pipe 63 communicates with the first expansion chamber X. At the same time, the first expansion chamber X and the second expansion chamber Z communicate with each other by passing through the second partition wall 62 across the third expansion chamber Y and the rear opening end 63b communicating with the second expansion chamber Z. Has been.

Further, as shown in FIG. 3A, a communication pipe 64 having a diameter larger than that of the communication pipe 63 is fixed to the second partition wall 62 at a position where it does not interfere with the communication pipe 63. As shown in FIG. 2, the communication pipe 64 has a front opening end 64 a communicating with the third expansion chamber Y and a rear opening end 64 b communicating with the second expansion chamber Z. Z is in communication.
Inside the communication pipe 64, a communication pipe 65 that is smaller in diameter than the communication pipe 64 and that is fixed through the rear end wall (partition wall) 66 of the muffler 26 is disposed therethrough. The communication pipe 65 communicates with the third expansion chamber Y at a position where the front opening end 65a crosses the second expansion chamber Z and the front opening end 65a protrudes from the front opening end 64a of the communication pipe 64, and the rear opening end. When 65b communicates with the space outside the muffler 26, it functions as a tail pipe that communicates the third expansion chamber Y in the muffler 26 and the space outside the muffler 26.
A tail cover 67 is fixed to the rear end portion of the muffler 26, and the tail cover 67 is formed in a bowl shape covering the rear end portion 65b of the communication pipe 65, that is, the periphery of the outlet portion of the tail pipe. .

With the above configuration, the exhaust gas discharged from the engine 6 passes through the communication pipe 63 after passing through the extension pipe 25c and entering the first expansion chamber X in the muffler 26 as shown by the arrow in FIG. And enters the second expansion chamber Z, where the exhaust gas flow is reversed in the muffler 26 by passing through the gap between the communication pipe 65 and the communication pipe 64 and enters the third expansion chamber Y. Thereafter, the flow direction is reversed again, passes through the communication pipe 65, and is discharged out of the muffler 26.
In this way, the exhaust gas passes through the three expansion chambers X, Y, and Z and is expanded in each expansion chamber, and the flow of the exhaust gas is reversed a plurality of times in the muffler 26 to increase the exhaust path length. Since the three-pass structure is employed, the exhaust gas can be reduced in the muffler 26 to reduce the exhaust noise.

In this configuration, the communication pipes 64 and 65 penetrating the second partition wall 62 are arranged inside the one communication pipe 64 so as to penetrate the other communication pipe 65, so that the communication pipes 64 and 65 are spaced at regular intervals. The arrangement space of the communication pipes 64 and 65 can be reduced as compared with the case where they are arranged side by side and arranged on the partition wall 62, and the degree of freedom of arrangement of the communication pipes is improved.
In particular, in this configuration, a communication pipe (tail pipe) that connects the expansion chamber Y and the outside of the muffler 26 across the one expansion chamber Z inside the communication pipe 64 that communicates between the adjacent expansion chambers Y and Z. ) 65 is arranged, so that a three-pass structure that is effective for sound reduction is simple pipe arrangement compared to the case where the three communication pipes 63 to 65 penetrating the partition wall 62 are arranged at regular intervals. In addition, the options for the arrangement of the tail pipe (communication pipe 65) can be expanded.
In this embodiment, as shown in FIG. 3A, the tail pipe (communication pipe 65) is arranged coaxially with the communication pipe 64, and is fixed to the rear end wall 66 only and cantilevered. However, as shown in FIG. 3B, the tail pipe is spot welded by bringing the tail pipe close to the inner peripheral surface of the communication pipe 64 and spot welding the tail pipe and the communication pipe 64. Both ends may be supported by the portion and the rear end wall 66.

FIG. 4A shows another embodiment. This figure shows a sectional view of the vicinity of the second partition wall 62a when the muffler 26 is formed in an elliptical cylindrical shape. In the following description, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.
In this configuration, the second partition wall 62a is formed in an elliptical shape, and the communication pipes 63 and 64 are arranged at intervals in the longitudinal direction of the second partition wall 62a, and a tail pipe is provided inside the communication pipe 64. A functioning communication pipe 65 is disposed so as to penetrate therethrough. Thereby, even if the length of the longitudinal direction of the 2nd partition 62a is comparatively shortened, the three communicating pipes 63, 64, and 65 can be efficiently arrange | positioned using a partition surface effectively.
In this case as well, as shown in FIG. 4B, the communication pipe 65 functioning as a tail pipe is brought close to the inner peripheral surface of the communication pipe 64, and the tail pipe and the communication pipe 64 are spot-welded. Thus, the tail pipe may be supported at both ends by the spot weld and the rear end wall 66. Moreover, the shape of the muffler and the partition is an example, and is not limited thereto, and may be another irregular shape.

FIG. 5 shows another embodiment.
In this embodiment, the expansion chamber Y corresponds to the first expansion chamber, the expansion chamber X corresponds to the second expansion chamber, and the expansion chamber Z corresponds to the third expansion chamber.
In the muffler 126, a communication pipe 70 having a diameter larger than that of the extension pipe (communication pipe) 125c of the exhaust pipe 125b is fixed to the first partition wall 61 at a position slightly shifted from the center of the first partition wall 61. The extension pipe 125c is disposed through the communication pipe 70, and the outlet 125d of the extension pipe 125c communicates with the first expansion chamber Y.
The front opening end 70a of the communication pipe 70 communicates with the second expansion chamber X, and the rear opening end 70b communicates with the first expansion chamber Y so that the adjacent expansion chambers X and Y communicate with each other. The outlet 125d of the pipe 125c communicates with the first expansion chamber Y at a position protruding from the rear opening end 70b of the communication pipe 70.

Further, in the gap between the communication pipe 70 and the extension pipe 125c, a catalyst body 100 that removes hydrocarbons, carbon monoxide, and nitrogen oxide in the exhaust gas by oxidation and reduction reactions is disposed.
The catalyst body 100 is applied with a honeycomb three-way catalyst formed by coating a porous honeycomb structure with platinum, palladium, rhodium, etc., and the inner peripheral side portion 101 of the catalyst body 100 is an extension pipe. It is arranged in close contact with the outer peripheral surface 125e of 125c. As another configuration of the catalyst body 100, as shown in FIG. 6, a heat pipe carrying platinum, palladium, rhodium or the like is applied to the punching pipe 110 whose both ends are in close contact with the outer peripheral surface 125e of the extension pipe 125c. May be. In addition, these structures are examples, Comprising: It is not limited to this, Other structures may be sufficient.

Further, the first partition wall 61 is fixed with a communication pipe 71 penetrating at a position where it does not interfere with the communication pipe 70, and the communication pipe 71 has a front opening end 71 a communicating with the second expansion chamber X, and The second expansion chamber X and the third expansion chamber Z are communicated with each other by passing through the second partition wall 62 across the first expansion chamber Y and the rear opening end 71b communicating with the third expansion chamber Z. Yes.
A communication pipe 72 is fixed through the rear end wall 66 of the muffler 126, the front opening end 72 a of the communication pipe 72 communicates with the third expansion chamber Z, and the rear opening end 72 b is a space outside the muffler 126. Thus, the communication pipe 72 functions as a so-called tail pipe.

  With the above configuration, the exhaust gas discharged from the engine 6 passes through the extension pipe 125c and enters the first expansion chamber Y in the muffler 126 as shown by an arrow in FIG. By reversing and passing through the gap between the communication pipe 70 and the extension pipe 125c, it passes through the catalyst body 100, and hydrocarbons, carbon monoxide, and nitrogen oxide in the exhaust gas are removed by oxidation and reduction reactions. Then, it enters the second expansion chamber X, reverses the flow direction again there, passes through the communication pipe 71 and enters the third expansion chamber Z, then passes through the communication pipe (tail pipe) 72 and goes through the muffler 126. Discharged outside.

Here, the catalyst body 100 generally exhibits its ability by reaching an activation temperature (about 300 ° C.).
In this configuration, the catalyst body 100 is communicated with the extension pipe 125c located on the most upstream side in the exhaust path in the muffler 126 and the exhaust gas immediately after entering the first expansion chamber Y from the extension pipe 125c. Since the catalyst body 100 is disposed in the gap with the pipe 70, the catalyst body 100 is not only heated by the heat of the exhaust gas passing through the catalyst body 100, but also radiated from the extension pipe 125c through which the high-temperature exhaust gas passes. As a result, the inner peripheral portion 101 is also warmed.
For this reason, the catalyst body is also warmed by heat radiation from the extension pipe 125c without increasing the number of parts as compared with the case where a heat transfer component that conducts heat of the upstream portion of the communication pipe is arranged on the outer periphery of the catalyst body. In addition, since the inner peripheral portion 101 corresponding to the substantially central portion of the catalyst body 100 is warmed, for example, even when the engine is cold, the entire catalyst body can be recovered in a relatively short time immediately after the engine 6 is started. The temperature can be the activation temperature.

By the way, conventionally, in order to promote the activation of the catalyst body, the catalyst body may be arranged immediately after the extension pipe of the exhaust pipe. However, if the catalyst body is disposed immediately after the extension pipe, the exhaust resistance increases, which may affect the engine output.
In this configuration, as described above, since the relatively high temperature exhaust gas immediately after being discharged from the extension pipe 125c and entering the first expansion chamber Y passes through the catalyst body 100, the catalyst body is disposed immediately after the extension pipe. The activation of the catalyst body can be promoted by the heat of the high-temperature exhaust gas while reducing the influence on the engine output as compared with the case of doing so.

Further, since the catalyst body 100 is arranged in the gap between the extension pipe 125 and the communication pipe 70, it is not necessary to provide a space for arranging the catalyst body 100 separately from the space for arranging the communication pipe, and the catalyst body 100 is limited. Further, it can be easily arranged in the space of the muffler 126, and the degree of freedom of arrangement of the communication pipe is improved.
Further, since the communication pipe 70 and the extension pipe 125c penetrating the first partition wall 61 are arranged inside the one communication pipe 70 so as to penetrate the other extension pipe 12c, the pipes 70 and 125c are spaced apart from each other. Therefore, compared with the case where the first partition wall 61 is disposed, the space for arranging these pipes can be reduced, and the degree of freedom in arranging the communication pipes is improved.

FIG. 7 shows another embodiment.
In this embodiment, the expansion chamber Y corresponds to the first expansion chamber, the expansion chamber Z corresponds to the second expansion chamber, and the expansion chamber X corresponds to the third expansion chamber.
In the muffler 226, the extension pipe 225c of the exhaust pipe 125b is fixed to the first partition 61 at a position slightly shifted from the center of the first partition 61, and the outlet 225d of the extension pipe 225c is connected to the first partition 61. It communicates with the expansion chamber Y.
In addition, a relatively large-diameter communication pipe 80 is fixed to the first partition wall 61 at a position where it does not interfere with the extension pipe 225c, and the front opening end 80a of the communication pipe 80 communicates with the third expansion chamber X. In addition, the second expansion chamber Y passes through the second partition wall 62 and the rear opening end 80b communicates with the second expansion chamber Z, so that the second expansion chamber Z and the third expansion chamber X are connected to each other. It is communicated.

A communication pipe 81 having a smaller diameter than the communication pipe 80 is disposed inside the communication pipe 80. The communication pipe 81 is fixed through the rear end wall 66 of the muffler 226, and the front opening end 81a communicates with the third expansion chamber X at a position protruding from the front opening end 80a of the communication pipe 80. The rear opening end 81b communicates with a space outside the muffler 226, so that the communication pipe 81 functions as a so-called tail pipe.
In addition, a communication pipe 82 is fixed to the second partition wall 62 at a position where it does not interfere with the communication pipe 80, and a front opening end 82 a of the communication pipe 82 communicates with the first expansion chamber Y, and a rear opening. The end 82 b communicates with the second expansion chamber Z, and the adjacent expansion chambers Y and Z communicate with each other by the communication pipe 82. In this configuration, a double pipe composed of the communication pipes 80 and 81 is disposed in the first partition wall 61 and the second partition wall 62.

  With the above configuration, the exhaust gas discharged from the engine 6 passes through the extension pipe 225c and enters the first expansion chamber Y in the muffler 226 and then passes through the communication pipe 82 as shown by the arrow in FIG. And enters the second expansion chamber Z, where it passes through the gap between the communication pipe 80 and the communication pipe 81, thereby reversing the flow of the exhaust gas in the muffler 226 and entering the third expansion chamber X. Thereafter, the flow direction is reversed again, passes through the communication pipe 81, and is discharged outside the muffler 226.

  In this configuration, the communication pipes 80 and 81 penetrating the partition walls 61 and 62 are disposed inside the one communication pipe 80 so as to penetrate the other communication pipe 81, so that the communication pipes 80 and 81 are arranged at a constant interval. The arrangement space of the communication pipes can be reduced as compared with the case where they are arranged side by side and arranged on the partition walls 61 and 62, and the degree of freedom of arrangement of the communication pipes is improved.

FIG. 8 shows another embodiment.
In the muffler 326, the cylindrical main body 60 is partitioned into four expansion chambers W, X, Y, and Z through a first partition wall 61, a second partition wall 62, and a third partition wall 90. In this embodiment, the expansion chamber Y corresponds to the first expansion chamber, the expansion chamber X corresponds to the second expansion chamber, the expansion chamber Z corresponds to the third expansion chamber, and the expansion chamber W corresponds to the fourth expansion chamber. It corresponds.
The extension pipe 325c of the exhaust pipe 125b is fixed so as to pass through positions shifted from the centers of the first partition wall 61 and the second partition wall 62, and the outlet 325d of the extension pipe 325c communicates with the first expansion chamber Y.
A large-diameter communication pipe 91 penetrates and is fixed to the second partition wall 62 in a substantially central region that does not interfere with the extension pipe 325c, and the front opening end 91a of the communication pipe 91 communicates with the second expansion chamber X. The rear opening end 91b communicates with the first expansion chamber Y so that the adjacent expansion chambers X and Y communicate with each other.

A communication pipe 92 having a smaller diameter than that of the communication pipe 91 is disposed inside the communication pipe 91. The communication pipe 92 is fixed through the third partition wall 90, crosses the first expansion chamber Y, and the front opening end 92 a is located at a position where the front opening end 92 a protrudes from the front opening end 91 a of the communication pipe 91. The rear opening end 92b communicates with the third expansion chamber Z, and the second expansion chamber X and the third expansion chamber Z communicate with each other.
Further, a communication pipe 93 having a diameter smaller than that of the communication pipe 92 is disposed inside the communication pipe 92. The communication pipe 93 is fixed through the first partition wall 61 and has a front opening end 93a. Communicates with the fourth expansion chamber W, and the rear opening 93b communicates with the third expansion chamber Z, whereby the third expansion chamber Z and the fourth expansion chamber W communicate with each other.

  Further, the first partition wall 61 has a communication pipe 94 penetrating and fixed at a position where it does not interfere with the extension pipe 325 c and the communication pipe 93, and the communication pipe 94 includes the second expansion chamber X, the first expansion chamber Y, and the like. The second partition 62, the third partition 90, and the rear end wall 66 of the muffler 326 are fixed so as to cross the third expansion chamber Z, and the front opening end 94a thereof opens to the fourth expansion chamber W. The rear opening end 94b communicates with the space outside the muffler 326, and functions as a tail pipe that communicates the fourth expansion chamber W and the space outside the muffler 326.

With the above configuration, the exhaust gas discharged from the engine 6 passes through the extension pipe 325c and enters the first expansion chamber Y in the muffler 326 as shown by an arrow in FIG. By passing through the gap between the pipe 92 and the exhaust gas flow in the muffler 326 and entering the second expansion chamber X, the flow direction is reversed again, and the communication pipe 92 and the communication pipe 93 are reversed. And enters the third expansion chamber Z.
The exhaust gas that has entered the third expansion chamber Z then reverses the flow direction again, passes through the communication pipe 93 and enters the fourth expansion chamber W, and then reverses the flow direction to communicate with the communication pipe 94. And is discharged out of the muffler 326.

In this configuration, the exhaust gas passes through the four expansion chambers W, X, Y, and Z and is expanded in each expansion chamber, and the flow of the exhaust gas is reversed a plurality of times in the muffler 326 to increase the exhaust path length. Since a so-called double three-pass structure is adopted, the exhaust noise can be reduced by lowering the exhaust gas pressure.
In addition, the three communication pipes 91, 92, and 93 that penetrate the partition wall 62 are arranged inside the communication pipe 91 so as to penetrate the communication pipe 92, and the communication pipe 93 is penetrated inside the communication pipe 92. Since the three communication pipes 91 to 93 are arranged at regular intervals, the space for arranging the communication pipes can be reduced, and the communication pipes can be arranged freely. The degree is improved.

  As mentioned above, although this invention was demonstrated based on one Embodiment, it is clear that this invention is not limited to this. For example, in the above embodiment, the communication pipe is a double pipe or a triple pipe, but is not limited to this, and may be a multiple pipe beyond that. Moreover, in the said embodiment, although the case where the inside of a muffler was divided into three rooms or four rooms was illustrated, it is not limited to this, You may make it partition into two rooms or five or more rooms. Moreover, although the exhaust structure of the motorcycle has been described in the above embodiment, the present invention can be applied to other exhaust structures such as three-wheeled vehicles and four-wheeled vehicles classified as ATV (rough terrain vehicle).

1 is a side view of an overall configuration of a motorcycle according to an embodiment. It is a structural diagram of a muffler. A is a cross-sectional view in the vicinity of the second partition wall of the muffler, and B is a cross-sectional view in the vicinity of the second partition wall when the tail pipe is spot welded to the communication pipe. A is a cross-sectional view in the vicinity of the second partition wall of the muffler showing another embodiment, and B is a cross-sectional view in the vicinity of the second partition wall when the tail pipe is spot welded to the communication pipe. It is a structural diagram of a muffler showing another embodiment. It is a figure which shows the other structural example of a catalyst body. It is a structural diagram of a muffler showing another embodiment. It is a structural diagram of a muffler showing another embodiment.

Explanation of symbols

1 Motorcycle (vehicle)
6 Engine 25c, 125c, 225c, 325c Extension pipe (communication pipe)
26, 126, 226, 326 Muffler (exhaust system)
60 cylindrical body 61 first partition 62, 62a second partition 63-65, 70-72, 80-82, 91-94, P1-P3 communication pipe 90 third partition 100 catalyst body 110 punching pipe W, X, Y , Z Expansion chamber

Claims (5)

In a vehicle exhaust system comprising a partition wall that divides the inside of the muffler into a plurality of expansion chambers and a plurality of communication tubes that pass through the partition wall, in a muffler connected to an exhaust pipe extending from the engine,
An exhaust system for a vehicle, wherein, among the plurality of communication pipes, another communication pipe is disposed inside one communication pipe.   The one communication pipe communicates between adjacent expansion chambers, and the other communication pipe passes through at least one of the adjacent expansion chambers and penetrates another partition wall. The vehicle exhaust system as described.   The exhaust system for a vehicle according to claim 2, wherein the other communication pipe is a tail pipe that discharges exhaust gas to the outside of the muffler.   The upstream open end of the other communication pipe is opened upstream from the open end of the one communication pipe, and the catalyst body is disposed between the other communication pipe and the one communication pipe. The exhaust system for a vehicle according to claim 1, wherein 5. The vehicle exhaust device according to claim 4, wherein the other communication pipe is an extension pipe of the exhaust pipe.

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