JP7384112B2 - scarf - Google Patents

Description

The present invention relates to a muffler that discharges engine exhaust gas to the outside of the engine.

Generally, devices such as vehicles equipped with an engine are equipped with a muffler. The muffler has a function of reducing noise generated when exhaust gas from the engine is released to the outside of the engine. In some mufflers, the internal space of the muffler is divided into multiple chambers by partition walls for the purpose of improving the muffler's noise reduction performance, and a pipe is provided inside the muffler to communicate between each chamber. Some devices have a structure in which exhaust gas introduced into the interior moves between each chamber via a pipe. Further, some mufflers include a catalyst provided inside the muffler for purifying exhaust gas. Patent Document 1 listed below describes a muffler in which a plurality of expansion chambers are formed, a pipe for communicating between the expansion chambers is provided, and a catalyst is provided.

Patent No. 6426500

When a muffler has a structure in which multiple chambers are formed inside, pipes are provided to communicate between the chambers, and a catalyst is provided, there are many components such as the pipes, the catalyst, and the members that support them. The parts must be placed inside the muffler. Therefore, there is a risk that the muffler will become larger. As the muffler becomes larger, the appearance (design) of the vehicle in which it is installed may deteriorate. Furthermore, in the case of a muffler for a saddle type vehicle, the bank angle of the saddle type vehicle may be limited due to the increase in size of the muffler. Further, when many of the above-mentioned parts are arranged inside the muffler, the space through which exhaust gas flows becomes smaller inside the muffler, and there is a possibility that the muffler's muffling performance may deteriorate.

Furthermore, in many vehicles, the muffler is located away from the engine. For example, in a straddle-type vehicle, the engine is disposed approximately at the center in the longitudinal direction of the vehicle, and the muffler is disposed at the rear of the vehicle. Furthermore, in most four-wheeled motor vehicles, the engine is located at the front of the vehicle, and the muffler is located at the rear of the vehicle. The temperature of the catalyst increases as high-temperature exhaust gas flows through the catalyst, and the catalyst becomes activated. When a catalyst is installed inside a muffler located far from the engine, the temperature of the exhaust gas decreases while it reaches the muffler from the engine, and therefore the temperature of the exhaust gas flowing inside the catalyst decreases. As a result, activation of the catalyst may be delayed.

The present invention has been made in view of the above-mentioned problems, for example, and an object of the present invention is to provide a muffler that can be downsized and that can accelerate the activation of the catalyst provided inside. There is a particular thing.

In order to solve the above problems, a first muffler of the present invention includes a cylindrical muffler body having an internal space through which exhaust gas flows, and first muffler bodies arranged in the X direction within the muffler body by partitioning the internal space. a first wall portion forming a chamber and a second chamber; and a first wall portion forming a chamber and a second chamber; communicating with another chamber other than the second chamber, between the second chamber and the outside of the muffler body, or between the second chamber and the other chamber within the muffler body; A communication pipe and a catalyst provided in the internal space to purify the exhaust gas, a catalyst support hole is provided in a central portion of the first wall, and the catalyst is provided in the catalyst support hole. is supported, a notch is formed in the outer edge side of the first wall, and a gap between the first chamber and the second chamber is formed between the notch and the muffler body. An exhaust gas flow gap is formed between the first chamber and the second chamber to allow the exhaust gas to flow between the first chamber and the second chamber , one end of the communication tube is closed, and one end of the communication tube is closed. Punching holes are formed in the peripheral wall of the side portion, and the catalyst is adjacent to a portion of the communication pipe in which the punching holes are formed.
Further, the second muffler of the present invention includes a cylindrical muffler body having an internal space through which exhaust gas flows, and a first chamber and a second chamber arranged in the X direction within the muffler body by partitioning the internal space. A first wall forming a chamber, between the first chamber and the second chamber, and between the first chamber and the muffler body other than the first chamber or the second chamber. a communication pipe that communicates with another chamber, between the second chamber and the outside of the muffler body, or between the second chamber and the other chamber in the muffler body; a catalyst provided in a space to purify the exhaust gas; a catalyst support hole is provided in a central portion of the first wall; the catalyst is supported in the catalyst support hole; A notch is formed in an outer edge side portion of the wall portion of the first wall, and between the notch and the muffler body, the first chamber and the second chamber are communicated with each other, and the first chamber is connected to the second chamber. An exhaust gas flow gap is formed between the chamber and the second chamber to allow the exhaust gas to flow; in the muffler body, the second chamber is located on one side in the X direction; A chamber is located on the other side of the second chamber in the X direction, and a second chamber that closes the other side of the first chamber in the X direction is located on the other side of the first chamber in the X direction. The communication pipe is located on one side in the Y direction perpendicular to the X direction, the catalyst is located on the other side in the Y direction, and the outlet of the catalyst is located in the first chamber. The second wall is open and faces the second wall, and the second wall is connected to one end of the second wall in the Y direction and the first wall in the Y direction. the first wall so that the distance between the second wall and the first wall is greater than the distance between the second wall and the first wall in the Y direction; It is characterized by being inclined with respect to the wall of 1.

According to the present invention, the muffler can be made smaller and the catalyst provided inside the muffler can be activated more quickly.

FIG. 1 is an explanatory diagram showing a vehicle equipped with a muffler according to an embodiment of the present invention. It is an external view showing the muffler of the example of this invention seen from the back. It is an external view showing the muffler of the example of the present invention seen from above. 4 is a sectional view showing a cross section of the muffler taken along cutting line IV-IV in FIG. 3. FIG. 5 is a sectional view showing a cross section of the muffler taken along cutting line VV in FIG. 4. FIG. It is an explanatory view showing a partition in a muffler of an example of the present invention. It is a schematic diagram showing the flow of exhaust gas in the muffler of the example of the present invention.

A muffler according to an embodiment of the present invention includes a cylindrical muffler body having an internal space through which exhaust gas flows, and a first chamber and a second chamber arranged in the X direction within the muffler body by partitioning the internal space. between the first wall, the first chamber and the second chamber; between the first chamber and another chamber other than the first chamber or the second chamber in the muffler body; A communication pipe that communicates between the chamber and the outside of the muffler body or between the second chamber and another chamber in the muffler body, and a catalyst that is provided in the internal space and purifies exhaust gas. There is.

Furthermore, in the muffler of this embodiment, a catalyst support hole is provided in the central portion of the first wall portion, and a catalyst is supported within the catalyst support hole. Further, a notch is formed in the outer edge side portion of the first wall, and between the notch and the muffler body, the first chamber and the second chamber are communicated with each other, and the first chamber and the second chamber are connected to each other. An exhaust gas flow gap is formed between the first chamber and the second chamber to allow exhaust gas to flow therethrough.

In the muffler of this embodiment having such a configuration, the catalyst is supported by the central portion of the first wall, and the exhaust gas flow gap is formed between the notch formed in the outer edge portion of the first wall. It is formed between the muffler body. That is, the exhaust gas flow gap is located on the outer peripheral side of the catalyst. Therefore, the exhaust gas flowing through the exhaust gas flow gap and moving between the first chamber and the second chamber passes along the outer peripheral side of the catalyst. As a result, the exhaust gas just before flowing into the exhaust gas flow gap and the exhaust gas just after flowing out from the exhaust gas flow gap tend to hit the outer circumferential surface of the catalyst. Therefore, a large amount of exhaust gas can be applied to the outer peripheral surface of the catalyst. Therefore, the temperature of the catalyst can be increased in a short time using the heat of the exhaust gas, and activation of the catalyst can be accelerated.

Furthermore, in the muffler of the present embodiment, the exhaust gas flow gap between the notch in the first wall and the muffler body creates a flow path through which exhaust gas flows between the first chamber and the second chamber. is formed. Therefore, the structure of the muffler can be simplified compared to the case where a flow path for circulating exhaust gas is formed between the first chamber and the second chamber by using a member such as a pipe, The muffler can be downsized. Further, the number of parts installed inside the muffler can be reduced, and even though a catalyst is provided inside the muffler, a large space can be created in the muffler for the exhaust gas to flow, and the muffler's muffling performance can be improved.

FIG. 1 shows a vehicle 1 equipped with a muffler 21 according to an embodiment of the present invention. FIG. 2 shows the right muffler 21 viewed from the rear. FIG. 3 shows the right muffler 21 viewed from above. In addition, in the examples, when explaining the front (Fd), rear (Bd), upper (Ud), lower (Dd), left (Ld), and right (Rd) directions, the directions in FIGS. Follow the arrow drawn at the bottom left of.

In FIG. 1, a vehicle 1 is a straddle-type vehicle, for example, a motorcycle. A vehicle 1 has a body frame 2, and a steering shaft 3 is provided at the front of the body frame 2. Further, a front fork 4 is connected to the steering shaft 3, and a front wheel 5 is supported by the front fork 4. Further, a handle 6 is attached to the steering shaft 3. On the other hand, a swing arm 7 is provided at the rear of the vehicle body frame 2, and a rear wheel 8 is supported on the swing arm 7. Further, an engine 9 is provided approximately at the center of the vehicle body frame 2 in the longitudinal direction. The engine 9 has a crankcase 10, a cylinder block 11, and a cylinder head 12. Further, a driver seat 13 is provided behind and above the engine 9, and a tandem seat 14 is provided behind the driver seat 13. Note that in the vehicle 1 of this embodiment, the driver seat 13 and the tandem seat 14 are integrated.

The vehicle 1 is also provided with an exhaust device 15 that discharges exhaust gas from the engine 9 to the outside of the engine 9. The exhaust device 15 includes four exhaust pipes 16, two collecting pipes 17, one chamber 18, two connecting pipes 19, and two mufflers 21. In FIG. 1, among the components of the exhaust device 15, two exhaust pipes 16 placed on the right side, one collecting pipe 17 placed on the right side, a chamber 18, and one exhaust pipe placed on the right side. Only the connecting pipe 19 and one muffler 21 located on the right side are shown.

The engine 9 in this embodiment is a four-cylinder engine in parallel, and four exhaust ports are provided at the front of the cylinder head 12 to correspond to the respective cylinders. One end portion of the four exhaust pipes 16 is connected to each of the four exhaust ports. Each exhaust pipe 16 extends from the front of the engine 9 to the bottom. Below the engine 9, the other ends of the two exhaust pipes 16 on the right side are connected to the front ends of the collecting pipe 17 on the right side, and the other ends of the two exhaust pipes 16 on the left side are connected to the front end part of the collecting pipe 17 on the left side. Connected to the front end. The chamber 18 is disposed at the lower and rearward position of the engine 9 at approximately the center in the left-right direction, and the rear end portions of the two collecting pipes 17 are connected to the front portion of the chamber 18 . Further, the two mufflers 21 are arranged on the right side and the left side of the rear wheel 8 at the rear of the vehicle 1, respectively. One end of a right connecting pipe 19 is connected to the rear right part of the chamber 18, and the other end of this connecting pipe 19 is connected to the front end of the right muffler 21. Further, one end of a left connecting pipe 19 is connected to the rear left part of the chamber 18, and the other end of this connecting pipe 19 is connected to the front end of the left muffler 21.

Exhaust gas flowing out from each of the four exhaust ports of the engine 9 flows through four exhaust pipes 16 and two collecting pipes 17 and flows into the chamber 18 . The exhaust gas that has flowed into the chamber 18 flows through the chamber 18, flows through the two connecting pipes 19, and flows into the two mufflers 21, respectively. The exhaust gas that has flowed into each muffler 21 flows through each muffler 21 and is then released from each muffler 21 into the atmosphere behind it.

The two mufflers 21 have a symmetrical shape in appearance, and are arranged symmetrically with respect to the center of the vehicle 1 in the lateral direction. The right muffler 21 will mainly be described below.

The muffler 21 is formed into a cylindrical shape. In FIG. 1, a chain line P drawn on the muffler 21 indicates the axis of the muffler 21. The muffler 21 is arranged such that its axis P slopes upward from the front to the rear of the muffler 21. Further, the rear surface 22 of the muffler 21 (specifically, the rear surface of the tail cap 61) is inclined such that the upper portion of the rear surface 22 is located further back than the lower portion of the rear surface 22. Further, the front surface 23 (specifically, the front surface of the outer front wall 28) of the muffler 21 is also inclined in substantially the same direction as the rear surface 22. By providing the muffler 21 with such an inclination, the appearance (design) of the muffler 21 can be made sporty and full of dynamism.

Further, as shown in FIG. 2, when the muffler 21 is viewed from the rear, the rear surface 22 of the muffler 21 has a substantially inverted triangular shape. Similar to the shape of the rear surface 22 of the muffler 21, the cross-sectional shape of the muffler 21 is also approximately in the shape of an inverted triangle. Further, a dashed-dotted line Q in FIG. 2 is a straight line that divides the rear surface 22 or the cross section of the muffler 21 into two symmetrical parts, and is a reference line indicating the vertical direction of the muffler 21 itself. The muffler 21 is arranged so as to be inclined outward in the left-right direction of the vehicle 1 from the lower part to the upper part of the muffler 21. For example, as shown in FIG. 2, in the right muffler 21, the reference line Q is inclined clockwise by about 15 degrees with respect to the vertical direction. This means that when the right muffler 21 is viewed from the rear, the right muffler 21 is arranged so as to be inclined clockwise by about 15 degrees with respect to the vertical direction. Note that the left muffler 21 is arranged so as to be inclined by about 15 degrees counterclockwise with respect to the vertical direction when viewed from the rear. By making the cross-sectional shape of each muffler 21 substantially in the shape of an inverted triangle, and by arranging each muffler 21 so as to be inclined outward in the left-right direction of the vehicle 1 from the bottom to the top of the muffler 21, the bank angle of the vehicle 1 is can be made larger.

FIG. 4 shows a cross section of the muffler 21 cut along the cutting line IV-IV in FIG. 3, viewed from the right. FIG. 5 shows a cross section of the muffler 21 cut along the cutting line VV in FIG. 4, as seen from the rear. FIG. 6 shows only the partition wall 41 in FIG. 5 extracted. Here, an arrow X in FIG. 4 indicates a direction parallel to the axis P of the muffler 21. Hereinafter, this direction will be referred to as the X direction, one side (approximately the front) in the X direction will be referred to as the X1 direction or the X1 side, and the other side (approximately the rear) in the X direction will be referred to as the X2 direction or the X2 side. Further, arrow Y in FIGS. 4 to 6 indicates a direction perpendicular to the X direction. Hereinafter, this direction will be referred to as the Y direction, one direction (substantially upward) in the Y direction will be referred to as the Y1 direction or Y1 side, and the other direction (substantially downward) in the Y direction will be referred to as the Y2 direction or Y2 side. Note that the extension direction of the reference line Q in FIG. 2 is the Y direction. Further, arrow Z in FIGS. 5 and 6 indicates a direction perpendicular to both the X direction and the Y direction. Hereinafter, this direction will be referred to as the Z direction, one direction (approximately to the right) in the Z direction will be referred to as the Z1 direction or the Z1 side, and the other direction (approximately to the left) in the Z direction will be referred to as the Z2 direction or the Z2 side.

As shown in FIG. 4, the muffler 21 includes a muffler body 25, a partition wall 41, a connecting member 51, an introduction pipe 52, an enlarged diameter pipe 53, a catalyst 54, a reduced diameter pipe 55, a communication pipe 56, a discharge pipe 59, and a tail cap 61. and a bracket 63.

The muffler body 25 includes an outer circumferential wall 26, an inner circumferential wall 27 provided on the inner circumferential side of the outer circumferential wall 26, an outer front wall 28 that closes an end of the outer circumferential wall 26 in the X1 direction, and It has an inner front wall 29 provided, an outer rear wall 30 that closes the X2 direction end of the outer peripheral wall 26, and an inner rear wall 31 that closes the X2 direction end of the inner peripheral wall 27. The outer circumferential wall 26, the inner circumferential wall 27, the outer front wall 28, the inner front wall 29, the outer rear wall 30, and the inner rear wall 31 are each made of, for example, a metal material. Furthermore, an internal space 70 through which exhaust gas flows is formed within the muffler body 25. The internal space 70 is a space surrounded by the internal peripheral wall 27, the internal front wall 29, and the internal rear wall 31.

The outer circumferential wall 26 and the inner circumferential wall 27 are each formed into a substantially triangular tube shape, and the axes of the outer circumferential wall 26 and the inner circumferential wall 27 both coincide with the axis P. Furthermore, both the outer circumferential wall 26 and the inner circumferential wall 27 gradually expand in diameter from their X1 direction ends toward their X2 direction ends. Further, a gap is formed between the outer circumferential wall 26 and the inner circumferential wall 27 over the entire circumference.

The outer front wall 28 and the inner front wall 29 are formed in a cup shape whose diameter increases from the end of the muffler 21 in the X1 direction toward the X2 direction. The X2 direction end portions of the outer front wall 28 and the inner front wall 29 are joined to the X1 direction end portion of the outer peripheral wall 26 over the entire circumference by a joining means such as welding. Furthermore, introduction tube support holes 32 and 33 for inserting and supporting the introduction tube 52 are formed at the ends of the outer front wall 28 and the inner front wall 29 in the X1 direction, respectively.

The outer rear wall 30 and the inner rear wall 31 are each formed into a substantially flat plate shape. Further, the wall surface of the inner rear wall 31 is not perpendicular to the axis P. Specifically, the inner rear wall 31 is inclined such that the end of the inner rear wall 31 in the Y1 direction is located closer to the X2 side than the end of the inner rear wall 31 in the Y2 direction. The outer rear wall 30 is also inclined similarly to the inner rear wall 31. Further, the outer edge portion of the outer rear wall 30 is joined to the end portion of the outer peripheral wall 26 in the X2 direction over the entire circumference by a joining means such as welding. Further, the inner rear wall 31 is arranged on the X1 side of the outer rear wall 30, and the outer edge of the inner rear wall 31 is joined to the end of the inner peripheral wall 27 in the X2 direction over the entire circumference by a joining means such as welding. There is. In addition, exhaust pipe support holes 34 and 35 are formed in the outer rear wall 30 and the inner rear wall 31, respectively, through which the discharge pipe 59 is inserted and supported. Note that the inner rear wall 31 is a specific example of the second wall portion.

Furthermore, the protrusion 36 formed at the center of the inner rear wall 31 fits into the recess 37 formed at the center of the outer rear wall 30, so that the outer rear wall 30 and the inner rear wall 31 are mutually connected. Positioned. As a result, the X2 direction end of the outer peripheral wall 26 joined to the outer edge of the outer rear wall 30 and the X2 direction end of the inner peripheral wall 27 joined to the outer edge of the inner rear wall 31 are positioned. Further, a fixing member 38 is provided between the end portion of the outer peripheral wall 26 in the X1 direction and the end portion of the inner peripheral wall 27 in the X1 direction. The fixing member 38 supports the end portion of the inner peripheral wall 27 in the X1 direction inside the end portion of the outer peripheral wall 26 in the X1 direction.

The partition wall 41 is a wall that partitions the internal space 70 within the muffler body 25. The partition wall 41 is formed into a plate shape. Further, the partition wall 41 is arranged so that its wall surface is substantially orthogonal to the axis P. By partitioning the internal space 70 by the partition wall 41, a first chamber 71 and a second chamber 72 are formed in the muffler body 25, which are arranged next to each other in the X direction. In the muffler body 25, the first chamber 71 is located on the X2 side, and the second chamber 72 is located on the X1 side. Further, the partition wall 41 is arranged at a position closer to the X1 side than the center of the muffler body 25 in the X direction. The diameter of the inner peripheral wall 27 gradually increases from the end in the X1 direction to the end in the X2 direction, and the partition wall 41 is arranged at a position closer to the X1 side than the center of the muffler body 25 in the X direction. Therefore, the first chamber 71 has a larger volume than the second chamber 72. Note that the partition wall 41 is a specific example of the first wall portion.

Further, the first chamber 71 is a space surrounded by the X2 side portion of the inner circumferential wall 27, the inner rear wall 31, and the partition wall 41. The inner rear wall 31 has a distance between an end portion of the inner rear wall 31 in the Y1 direction and an end portion of the partition wall 41 in the Y1 direction. It is inclined with respect to the partition wall 41 so as to be larger than the distance. As a result, when the first chamber 71 is divided into two by a plane that includes the axis P and extends in the Z direction, the volume of the Y1 side region of the first chamber 71 is larger than the volume of the Y2 side region.

Further, the second chamber 72 is a space surrounded by the X1 side portion of the inner circumferential wall 27, the inner front wall 29, and the partition wall 41. The inner front wall 29 is configured such that the distance between the Y2 direction end portion of the inner front wall 29 and the Y2 direction end portion of the partition wall 41 is the same as the distance between the Y1 direction end portion of the inner front wall 29 and the Y1 direction end portion of the partition wall 41. It is inclined with respect to the partition wall 41 so as to be larger than the distance. As a result, when the second chamber 72 is divided into two by a plane that includes the axis P and extends in the Z direction, the volume of the Y2 side region of the second chamber 72 is larger than the volume of the Y1 side region.

Further, as shown in FIG. 5, the cross-sectional shape of the internal space 70 (the cross-sectional shape of the inner circumferential wall 27) is approximately an inverted triangular shape, and the partition wall 41 is approximately inverted triangular to match the cross-sectional shape of the internal space 70. formed into a shape. Furthermore, a portion of the outer edge of the partition wall 41 where a notch 45 (described later) is not formed is joined to the inner surface of the inner peripheral wall 27 by a joining means such as welding.

Furthermore, a catalyst support hole 42 and a communication tube support hole 43 are formed in the central portion of the partition wall 41 . The catalyst support hole 42 is a hole through which the catalyst 54 is inserted and supported. The communication tube support hole 43 is a hole through which the communication tube 56 is inserted and supported. The catalyst support hole 42 and the communication pipe support hole 43 are each arranged at the center of the wall surface of the partition wall 41 in the Z direction. Further, the catalyst support hole 42 and the communication pipe support hole 43 are arranged in the Y direction on the wall surface of the partition wall 41. In the wall surface of the partition wall 41, the communication pipe support hole 43 is located on the Y1 side, and the catalyst support hole 42 is located on the Y2 side. Further, the communication tube support hole 43 and the catalyst support hole 42 are adjacent to each other. Further, the diameter of the communication pipe support hole 43 is smaller than that of the catalyst support hole 42. Furthermore, notches 45 are formed at two locations on the outer edge side of the partition wall 41 . The cutout portion 45 will be explained in detail later.

In FIG. 4, the introduction pipe 52, the diameter-expanding pipe 53, the diameter-reducing pipe 55, the communication pipe 56, and the discharge pipe 59 are each formed of, for example, a metal pipe. The introduction pipe 52 is a pipe that introduces exhaust gas into the muffler body 25. As shown in FIG. 4, when the introduction tube 52 is viewed from the right, the introduction tube 52 extends in the X direction. The X1 direction end of the introduction tube 52 is inserted into the introduction tube support holes 32 and 33 of the outer front wall 28 and the inner front wall 29, and is joined to the introduction tube support holes 32 and 33 by a joining means such as welding. Supported. The opening on the end side in the X1 direction of the introduction pipe 52 corresponds to the exhaust gas inlet of the muffler 21. Further, the X2 side portion of the introduction pipe 52 extends toward the partition wall 41 in the Y2 side region within the second chamber 72. Further, a connecting member 51 formed in a cylindrical shape and made of, for example, a metal material is attached to the end of the introduction pipe 52 in the X1 direction. The connecting member 51 is a member that connects the connecting pipe 19 and the introduction pipe 52.

The enlarged diameter tube 53 is located in the Y2 side region within the second chamber 72. The enlarged diameter tube 53 extends in the X direction. The end of the enlarged diameter tube 53 in the X1 direction is connected to the end of the introduction tube 52 in the X2 direction, and both are joined together by a joining means such as welding. Further, the diameter of the X2 side portion of the enlarged diameter tube 53 increases as it goes in the X2 direction.

The catalyst 54 has a function of purifying exhaust gas. The catalyst 54 is, for example, a three-way catalyst. Catalyst 54 is located within interior space 70 . Further, the catalyst 54 has a cylindrical outer shape, and is arranged so that its axis is substantially parallel to the axis P of the muffler 21. The X1 side portion of the catalyst 54 (the inlet side of the catalyst 54) is located in the Y2 side region within the second chamber 72. Further, the X1 side end of the catalyst 54 is connected to the X2 side end of the expanded diameter tube 53, and both are joined to each other by a joining means such as welding. Further, the X2 side portion of the catalyst 54 (the exit side of the catalyst 54) is located in the Y2 side region within the first chamber 71. Further, the outlet of the catalyst 54 is open in the first chamber 71 and faces the inner rear wall 31.

Further, the catalyst 54 is inserted into the catalyst support hole 42 of the partition wall 41, and is supported by being joined to the catalyst support hole 42 by a joining means such as welding. The portion where the catalyst 54 is supported by the partition wall 41 is approximately at the center of the catalyst 54 in the X direction. The outer circumferential surface of the catalyst 54 at approximately the center in the X direction is located within the catalyst support hole 42, but most of the outer circumferential surface of the X1 side portion of the catalyst 54 is exposed in the second chamber 72, and the catalyst Most of the outer peripheral surface of the X2 side portion of 54 is exposed inside the first chamber 71.

The reduced diameter tube 55 is located in the Y2 side region within the first chamber 71. The reduced diameter tube 55 extends in the X direction. An end in the X1 direction of the reduced diameter tube 55 is connected to an end in the X2 direction of the catalyst 54, and both are joined together by a joining means such as welding. Further, the diameter of the X2 side portion of the reduced diameter tube 55 decreases in the X2 direction. Further, the outlet of the diameter-reducing tube 55, that is, the opening 55A on the X2 side of the diameter-reducing tube 55 opens in the first chamber 71 and faces the inner rear wall 31. Moreover, the diameter-expanding tube 53, the catalyst 54, and the diameter-reducing tube 55 are each arranged substantially coaxially and lined up in a straight line.

The communication pipe 56 is a pipe that communicates between the second chamber 72 and the outside of the muffler body 25 in cooperation with the discharge pipe 59 . The communication pipe 56 is arranged on the Y1 side of the catalyst 54 in the internal space 70 . The communication pipe 56 extends in the X direction. That is, the communication pipe 56 is arranged so that its axis is substantially parallel to the axis P of the muffler 21. Further, the communication pipe 56 is a pipe having a constant diameter from its end in the X1 direction to its end in the X2 direction. The X1 side portion of the communication tube 56 is located in the Y1 side region within the second chamber 72, and the X2 side portion of the communication tube 56 is located in the Y1 side region within the first chamber 71. Further, the communication pipe 56 is inserted into the communication pipe support hole 43 of the partition wall 41, and is supported by being joined to the communication pipe support hole 43 by a joining means such as welding.

A lid 57 is attached to the X1 side end of the communication tube 56, and the X1 side end of the communication tube 56 is closed by the lid 57. Further, a large number of punching holes 58 are formed in the peripheral wall of the X1 side portion of the communication pipe 56. Each punching hole 58 is a small hole that penetrates the peripheral wall of the communication tube 56. These punching holes 58 are formed over substantially the entire area of the peripheral wall of the communication pipe 56 located within the second chamber 72 . A large number of punching holes 58 are formed in the peripheral wall of the communication tube 56 from a position on the end side in the X1 direction to a position immediately in front of the partition wall 41.

Further, the communication pipe 56 and the catalyst 54 are adjacent to each other and are arranged substantially parallel to each other. The X1 side portion of the catalyst 54 is adjacent to the X1 side portion of the communication pipe 56 where the punched hole 58 is formed. Further, the outer diameter of the communication pipe 56 is smaller than the outer diameter of the catalyst 54.

The exhaust pipe 59 is a pipe that discharges exhaust gas to the outside of the muffler body 25. One end of the discharge pipe 59 is located in the Y1 side region within the first chamber 71. One end of the discharge pipe 59 is connected to the end of the communication pipe 56 in the X2 direction, and both are joined to each other by a joining means such as welding. The other side of the exhaust pipe 59 extends outside the muffler body 25 through exhaust pipe support holes 34 and 35 in the outer rear wall 30 and the inner rear wall 31. The opening 59A on the other side of the exhaust pipe 59 corresponds to the outlet of the exhaust gas in the muffler 21. Further, the discharge pipe 59 generally extends in the X direction, but in detail, it is bent in the Y direction at a point closer to one end than the center in the direction of extension. The other side of the muffler 21 extends linearly, but its direction of extension is inclined with respect to the axis P of the muffler 21. Further, the other side portion of the discharge pipe 59 is supported by being joined to the discharge pipe support holes 34 and 35 of the outer rear wall 30 and the inner rear wall 31 by a joining means such as welding.

Further, as shown in FIG. 6, notches 45 are formed at two locations on the outer edge side of the partition wall 41. As shown in FIG. The notches 45 are formed at two corners 41A, 41B located on the Y1 side among three corners 41A, 41B, 41C of the partition wall 41 formed in a substantially inverted triangular shape. Of the two notches 45, one notch 45 is formed by cutting off the end of the corner 41A on the Y1 side and Z1 side of the partition wall 41, and the other notch 45 is formed on the Y1 side and Z2 side of the partition wall 41. It is formed by cutting off the end of the side corner 41B. Note that the two-dot chain line in FIG. 6 indicates the outer shape of the partition wall 41 when the end of the corner 41A and the end of the corner 41B are not cut off.

Each notch 45 is formed at the outer edge side of the partition wall 41 from the outer circumferential side of the communicating tube support hole 43 (or the communicating tube 56) to the outer circumferential side of the catalyst supporting hole 42 (or the catalyst 54). Further, as shown in FIG. 5, the Y2 direction end portion 45A of each cutout portion 45 is located closer to the Y2 side than the portion 54A of the catalyst 54 that is closest to the Y1 side. That is, referring to the reference line Q in FIG. 2 that indicates the vertical direction of the muffler 21 itself, the lower end of each notch 45 is located below the top of the catalyst 54.

Further, between each notch 45 and the inner peripheral wall 27, the first chamber 71 and the second chamber 72 are communicated with each other, and an exhaust gas is provided between the first chamber 71 and the second chamber 72. An exhaust gas flow gap 46 is formed to allow gas to flow. The exhaust gas flow gaps 46 are formed at two locations on the Z1 side and the Z2 side of the boundary between the first chamber 71 and the second chamber 72 in the internal space 70. Each exhaust gas flow gap 46 is formed at the boundary between the first chamber 71 and the second chamber 72, extending from the outer circumferential side of the communication pipe 56 to the outer circumferential side of the catalyst 54. The Y2 direction end portion 46A of each exhaust gas flow gap 46 is located closer to the Y2 side than the portion 54A of the catalyst 54 that is closest to the Y1 side. That is, referring to the reference line Q in FIG. 2 that indicates the vertical direction of the muffler 21 itself, the lower end of each exhaust gas circulation gap 46 is located below the top of the catalyst 54. Further, as can be seen from FIGS. 4 and 5, the large number of punched holes 58 of the communication pipe 56 and the exhaust gas flow gap 46 are close to each other.

The tail cap 61 is a roughly bowl-shaped member that covers the end surface (rear surface) of the muffler body 25 in the X2 direction. The tail cap 61 is formed with a discharge pipe insertion hole 62 through which the discharge pipe 59 is inserted. Further, as shown in FIG. 3, a bracket 63 for attaching the muffler 21 to the vehicle 1 is provided on the Y1 side portion (upper part) of the muffler body 25.

FIG. 7 is a schematic diagram showing the flow of exhaust gas flowing through the internal space 70 of the muffler 21. As shown in FIG. Note that FIG. 7 shows the basic flow of exhaust gas within the internal space 70 in a very simplified manner, and the actual flow of exhaust gas is more complicated than this. In addition, in FIG. 7, the large white arrows with broken lines indicate the direction of exhaust gas flowing in the pipes provided in the muffler 21, such as the introduction pipe 52, the communication pipe 56, and the discharge pipe 59, and the large black arrows , indicating the direction of exhaust gas flowing outside these tubes within the interior space 70.

In FIG. 7, exhaust gas basically flows through the muffler 21 in approximately the order of arrows a, b, c, d, e, f, g, h, i, and j. That is, the exhaust gas flowing out from the chamber 18 flows into the introduction pipe 52 of the muffler 21 via the connecting pipe 19. The exhaust gas that has flowed into the introduction pipe 52 flows through the introduction pipe 52 in the direction of arrow a, then flows through the enlarged diameter pipe 53, and flows into the catalyst 54. The exhaust gas that has flowed into the catalyst 54 flows through the catalyst 54 and is purified, then flows out from the catalyst 54 in the direction of arrow b, and then flows through the diameter-reducing pipe 55 to the X2 side of the diameter-reducing pipe 55. The liquid flows out from the opening 55A to the Y2 side area in the first chamber 71.

Here, as described above, the outlet of the catalyst 54 and the opening 55A of the reduced diameter tube 55 face the inner rear wall 31. The inner rear wall 31 has a distance between the Y1 direction end portion of the inner rear wall 31 and the Y1 direction end portion of the partition wall 41 and the Y2 direction end portion of the inner rear wall 31 and the Y2 direction end portion of the partition wall 41. It is inclined with respect to the partition wall 41 so as to be larger than the distance between the partition wall 41 and the partition wall 41. With this structure, the exhaust gas flowing out from the opening 55A of the diameter-reducing pipe 55 hits the Y2 side portion of the inner surface of the inner rear wall 31, and moves toward the Y1 side in the direction of arrow c along the slope of the inner surface of the inner rear wall 31. Move to. Further, as described above, in the first chamber 71, the volume of the Y1 side region is larger than the volume of the Y2 side region. With this structure, the exhaust gas flowing out from the opening 55A of the diameter-reduced pipe 55 smoothly moves from the Y2 side region with a small volume to the Y1 side region with a large volume in the first chamber 71.

Subsequently, the exhaust gas that has moved to the Y1 side region in the first chamber 71 hits the Y1 side portion of the inner surface of the inner peripheral wall 27, changes direction in the direction of arrow d, and moves toward the partition wall 41. The exhaust gas that has moved toward the partition wall 41 flows in the direction of arrow e within the two exhaust gas flow gaps 46 and flows into the Y1 side region within the second chamber 72.

Here, as described above, the inner front wall 29 has a distance between the Y2 direction end portion of the inner front wall 29 and the Y2 direction end portion of the partition wall 41 and the Y1 direction end portion of the inner front wall 29 and the partition wall 41. It is inclined with respect to the partition wall 41 so as to be larger than the distance from the end portion in the Y1 direction. With this structure, the exhaust gas that has passed through each exhaust gas circulation gap 46 and flowed into the Y1 side region in the second chamber 72 hits the Y1 side portion of the inner surface of the inner front wall 29 and the inner surface of the inner front wall 29. Move toward the Y2 side in the direction of arrow f along the slope. Further, as described above, in the second chamber 72, the volume of the Y2 side region is larger than the volume of the Y1 side region. With this structure, the exhaust gas that has passed through each exhaust gas circulation gap 46 and flowed into the Y1 side region in the second chamber 72 is transferred from the Y1 side region with a small volume to the Y2 region with a large volume in the second chamber 72. Move smoothly to the side area.

Subsequently, the exhaust gas that has moved to the Y2 side region in the second chamber 72 hits the Y2 side portion of the inner surface of the inner peripheral wall 27, changes direction in the direction of arrow g, and moves toward the partition wall 41. The exhaust gas that has moved toward the partition wall 41 hits the Y2 side portion of the wall surface of the partition wall 41 facing the second chamber 72, and changes its direction in the direction of the arrow h. Thereafter, the exhaust gas in the second chamber 72 flows into the communication pipe 56 through the punched hole 58 of the communication pipe 56, flows in the communication pipe 56 in the direction of arrow i, and then flows into the exhaust pipe 59. The gas flows through the interior in the direction of arrow j and is discharged into the atmosphere from the opening 59A of the discharge pipe 59.

As explained above, in the muffler 21 according to the embodiment of the present invention, the catalyst support hole 42 is provided in the central portion of the partition wall 41 that divides the internal space 70 of the muffler body 25 into the first chamber 71 and the second chamber 72. A catalyst 54 is supported in the catalyst support hole 42, and a notch 45 is formed on the outer edge side of the partition wall 41. Between the notch 45 and the inner circumferential wall 27 of the muffler body 25, a An exhaust gas flow gap 46 is formed between the first chamber 71 and the second chamber 72 to allow exhaust gas to flow therethrough. In this configuration, the exhaust gas flow gap 46 is arranged on the outer peripheral side of the catalyst 54. Therefore, the exhaust gas flowing through the exhaust gas flow gap 46 and moving from the first chamber 71 to the second chamber 72 passes along the outer circumferential side of the catalyst 54 . As a result, the exhaust gas immediately before flowing into the exhaust gas distribution gap 46 and the exhaust gas immediately after flowing out from the exhaust gas distribution gap 46 tend to hit the outer circumferential surface of the catalyst 54. Therefore, a large amount of exhaust gas can be applied to the outer peripheral surface of the catalyst 54. Therefore, the temperature of the catalyst 54 can be raised in a short time using the heat of the exhaust gas, and the activation of the catalyst 54 can be accelerated. When the muffler 21 is arranged at a position away from the engine 9 as in the vehicle 1 shown in FIG. 1, the temperature of the exhaust gas decreases while the exhaust gas reaches the muffler 21 from the engine 9. However, by making it easier for the exhaust gas flowing through the muffler 21 to hit the outer peripheral surface of the catalyst 54 and increasing the amount of exhaust gas hitting the outer peripheral surface of the catalyst 54, the temperature rise of the catalyst 54 is accelerated, and the catalyst 54 is activated early. can be achieved.

Further, most of the outer circumferential surface of the X2 side portion of the catalyst 54 is exposed in the first chamber 71, and most of the outer circumferential surface of the X1 side portion of the catalyst 54 is exposed in the second chamber 72. There is. Therefore, the exhaust gas just before flowing into the exhaust gas distribution gap 46 tends to hit the outer peripheral surface of the X2 side portion of the catalyst 54, and the exhaust gas just after flowing out from the exhaust gas distribution gap 46 hits the outer peripheral surface of the X1 side portion of the catalyst 54. easy. Therefore, the exhaust gas can be applied to a wide range of the outer peripheral surface of the catalyst 54, and the temperature of the catalyst 54 can be increased quickly.

Furthermore, in the muffler 21 of this embodiment, a communication pipe support hole 43 is provided on the Y1 side of the catalyst support hole 42 in the central portion of the partition wall 41, a communication pipe 56 is supported in the communication pipe support hole 43, and a notch is provided. The portion 45 is formed on the outer edge side of the partition wall 41 from the outer circumferential side of the communication pipe 56 to the outer circumferential side of the catalyst 54 . According to this configuration, by supporting both the catalyst 54 and the communication pipe 56 by the partition wall 41, the support structure for the catalyst 54 and the communication pipe 56 can be simplified and the number of members for supporting them can be reduced. can. Furthermore, by forming the notch 45 from the outer circumferential side of the communication pipe 56 to the outer circumferential side of the catalyst 54, the exhaust gas circulation gap 46 can be enlarged, and the exhaust gas flow gap 46 can be enlarged. The area of the flow path for the flowing exhaust gas can be increased. Thereby, exhaust gas can be smoothly moved from the first chamber 71 to the second chamber 72. Further, the Y2 direction end portion 45A of the notch portion 45 is located closer to the Y2 side than the portion 54A of the catalyst 54 that is closest to the Y1 side. In this way, by extending the notch 45 to the outer circumferential side of the catalyst 54, the exhaust gas immediately before flowing through the exhaust gas circulation gap 46 and the exhaust gas immediately after flowing through the exhaust gas circulation gap 46 are directed to the outer circumferential surface of the catalyst 54. It can be made easier to hit.

Furthermore, in the muffler 21 of this embodiment, the partition wall 41 is formed in a substantially triangular shape to match the cross-sectional shape of the internal space 70, and the notches 45 are formed at the two corners 41A and 41B of the partition wall 41, respectively. There is. With this configuration, a large exhaust gas flow gap 46 can be easily formed, and the flow of exhaust gas from the first chamber 71 to the second chamber 72 can be facilitated.

Furthermore, in the muffler 21 of this embodiment, the outlet of the catalyst 54 and the opening 55A of the diameter-reducing tube 55 face the inner rear wall 31, and the inner rear wall 31 is located at the end portion of the inner rear wall 31 in the Y1 direction. and the end portion of the partition wall 41 in the Y1 direction is greater than the distance between the end portion of the inner rear wall 31 in the Y2 direction and the end portion of the partition wall 41 in the Y2 direction. There is. Further, in the first chamber 71, the volume of the Y1 side region is larger than the volume of the Y2 side region. With these structures, it is possible to easily create exhaust gas flows as shown by arrows b, c, d, and e in FIG. The exhaust gas flowing out to the Y2 side area in the chamber 71 is smoothly moved to the Y1 side area in the first chamber 71, and the exhaust gas is further passed through each exhaust gas circulation gap 46 into the second chamber 72. can be moved smoothly.

In the muffler 21 of this embodiment, the distance between the end portion of the inner front wall 29 in the Y2 direction and the end portion of the partition wall 41 in the Y2 direction is the same as the end portion of the inner front wall 29 in the Y1 direction. It is inclined with respect to the partition wall 41 so as to be larger than the distance from the end portion of the partition wall 41 in the Y1 direction. Further, in the second chamber 72, the volume of the Y2 side region is larger than the volume of the Y1 side region. With these structures, it is possible to easily create exhaust gas flows as shown by arrows f, g, and h in FIG. The exhaust gas that has entered the Y1 side region in the chamber 72 is smoothly moved to the Y2 side region in the second chamber 72, and then smoothly moved to the outer peripheral side of the X1 side portion of the catalyst 54, and further, It can be smoothly flowed into the communication pipe 56 through the punched hole 58 of the communication pipe 56. Further, when the exhaust gas flows through the Y1 side region in the second chamber 72 in the arrow g direction and the arrow h direction, the exhaust gas passes through the outer circumferential side of the X1 side portion of the catalyst 54. At this time, the exhaust gas hits the outer peripheral surface of the X1 side portion of the catalyst 54, and the temperature of the catalyst 54 increases due to the heat of the exhaust gas. Thereby, activation of the catalyst 54 can be accelerated.

Furthermore, in the muffler 21 of this embodiment, the X1 side end of the communication pipe 56 is closed, a punching hole 58 is formed in the peripheral wall of the X1 side portion of the communication pipe 56, and the catalyst 54 is inserted into the punched hole of the communication pipe 56. It is adjacent to the part where 58 is formed. As a result, as indicated by the arrow h in FIG. The temperature of the catalyst 54 can be quickly raised by the heat of the exhaust gas passing through the outer circumferential side of the portion.

Furthermore, in the muffler 21 of the present embodiment, the exhaust gas flow gap 46 between the notch 45 of the partition wall 41 and the inner circumferential wall 27 of the muffler body 25 allows exhaust gas to flow from the first chamber 71 to the second chamber 72. It forms a flow path. Therefore, the structure of the muffler 21 can be simplified compared to the case where a flow path for flowing exhaust gas from the first chamber 71 to the second chamber 72 is formed by using a member such as a pipe. 21 can be made smaller. In addition, the number of parts installed inside the muffler 21 can be reduced, and even though the catalyst 54 is installed inside the muffler 21, a large space can be created inside the muffler 21 to allow exhaust gas to flow, thereby improving the muffler 21's muffling performance. be able to.

Furthermore, the muffler 21 of this embodiment introduces exhaust gas from the outside of the muffler body 25 into the catalyst 54, causes it to flow from the catalyst 54 into the first chamber 71, and from the first chamber 71 into the exhaust gas distribution gap 46. It has a structure in which it flows into the second chamber 72 through the passageway and flows out from the second chamber 72 to the outside of the muffler body 25 through the communication pipe 56. With this structure, it is possible to obtain a good exhaust noise reduction effect while purifying exhaust gas.

In the above embodiment, cutouts 45 were formed in the two corners 41A and 41B of the partition wall 41, and exhaust gas flow gaps 46 were provided on the Z1 side and the Z2 side of the Y1 side of the internal space 70, respectively. However, the notch 45 may be formed only in one corner 41A of the partition 41, and the exhaust gas circulation gap 46 may be provided only on the Z1 side of the Y1 side of the internal space 70, or the other one of the partitions 41 may be The notch 45 may be formed only in the corner 41B, and the exhaust gas flow gap 46 may be provided only on the Z2 side of the Y1 side of the internal space 70.

Furthermore, the partition structure of the internal space of the muffler of the present invention is not limited to that of the above embodiment. For example, in the internal space 70 of the muffler 21 of the above embodiment, another chamber different from the first chamber 71 and the second chamber 72 is formed, and the exhaust gas that has passed through the catalyst flows into the other chamber, The exhaust gas that has flowed into the other chamber may be caused to flow from the other chamber into the first chamber 71 via a pipe or the like that communicates the other chamber with the first chamber 71 . In addition, instead of this, another chamber different from the first chamber 71 and the second chamber 72 is formed in the internal space 70 of the muffler 21 of the above embodiment between the communication pipe 56 and the discharge pipe 59, so that the communication The exhaust gas flowing through the pipe 56 may be made to flow into the other chamber, and the exhaust gas flowing into the other chamber may be made to flow into the exhaust pipe 59.

Further, in the above embodiment, the internal structure of the right muffler 21 has been explained by taking the vehicle 1 provided with two mufflers 21 as an example. In the vehicle 1 of the embodiment, the internal structure of the left muffler 21 may be the same (left-right symmetrical) as the internal structure of the right muffler 21, or the internal structure of the left muffler 21 may be the same as the internal structure of the right muffler 21. It is also possible to have a different structure. Alternatively, a single muffler 21 may be provided in the vehicle.

Furthermore, in the above embodiments, a muffler for a motorcycle was taken as an example, but the muffler of the present invention can also be applied to a straddle-type vehicle other than a motorcycle, and may even be applied to a vehicle other than a straddle-type vehicle. It can also be applied to devices other than vehicles having internal combustion engines.

Furthermore, the present invention can be modified as appropriate within the scope of the invention that does not contradict the gist or idea that can be read from the claims and the entire specification, and mufflers with such changes are also included in the technical idea of the present invention. It will be done.

21 Muffler 25 Muffler body 27 Inner peripheral wall 31 Inner rear wall (second wall)
41 Partition wall (first wall)
41A, 41B Corner 42 Catalyst support hole 43 Communication pipe support hole 45 Notch 46 Exhaust gas circulation gap 54 Catalyst 56 Communication pipe 57 Lid 58 Punching hole 70 Internal space 71 First chamber 72 Second chamber

Claims (6)

A cylindrical muffler body having an internal space through which exhaust gas flows;
a first wall portion forming a first chamber and a second chamber aligned in the X direction within the muffler body by partitioning the internal space;
between the first chamber and the second chamber; between the first chamber and another chamber in the muffler body other than the first chamber or the second chamber; between the second chamber; a communication pipe that communicates between the chamber and the outside of the muffler body or between the second chamber and the other chamber in the muffler body;
a catalyst provided in the internal space and purifying the exhaust gas,
A catalyst support hole is provided in the center side of the first wall, the catalyst is supported in the catalyst support hole, a notch is formed in the outer edge side of the first wall, and the catalyst is supported in the catalyst support hole. The first chamber and the second chamber are communicated between the notch and the muffler body, and the exhaust gas is circulated between the first chamber and the second chamber. An exhaust gas circulation gap is formed to
One end of the communication tube is closed, a punching hole is formed in a peripheral wall of the one end of the communication tube, and the catalyst is adjacent to a portion of the communication tube in which the punching hole is formed. A muffler characterized by: A communicating tube support hole is provided in the central portion of the first wall, the communicating tube is supported in the communicating tube supporting hole, and the catalyst supporting hole and the communicating tube supporting hole are connected to the first wall. The cutout portion is arranged in the Y direction perpendicular to the X direction in the central portion of the wall portion, and the notch portion is formed in the outer edge portion of the first wall portion from the outer circumferential side of the communication pipe to the outer circumferential side of the catalyst. The muffler according to claim 1, characterized in that: A cylindrical muffler body having an internal space through which exhaust gas flows;
a first wall portion forming a first chamber and a second chamber aligned in the X direction within the muffler body by partitioning the internal space;
between the first chamber and the second chamber; between the first chamber and another chamber in the muffler body other than the first chamber or the second chamber; between the second chamber; a communication pipe that communicates between the chamber and the outside of the muffler body or between the second chamber and the other chamber in the muffler body;
a catalyst provided in the internal space and purifying the exhaust gas,
A catalyst support hole is provided in the center side of the first wall, the catalyst is supported in the catalyst support hole, a notch is formed in the outer edge side of the first wall, and the catalyst is supported in the catalyst support hole. The first chamber and the second chamber are communicated between the notch and the muffler body, and the exhaust gas is circulated between the first chamber and the second chamber. An exhaust gas circulation gap is formed to
In the muffler body, the second chamber is located on one side of the X direction, the first chamber is located on the other side of the second chamber in the X direction, and the second chamber is located on the other side of the second chamber in the X direction. A second wall portion that closes the other side of the first chamber in the X direction is provided on the other side in the X direction, and the communication pipe is located on one side in the Y direction perpendicular to the X direction, The catalyst is located on the other side of the Y direction, the outlet of the catalyst is open in the first chamber and faces the second wall, and the second wall is located on the other side of the Y direction. The distance between the one end side portion of the second wall portion in the Y direction and the one end side portion of the first wall portion in the Y direction is the same as the distance between the other end side portion of the second wall portion in the Y direction and the first wall portion. A muffler, wherein the muffler is inclined with respect to the first wall portion so as to be greater than a distance from the other end side portion of the wall portion in the Y direction. A communicating tube support hole is provided in the central portion of the first wall, the communicating tube is supported in the communicating tube supporting hole, and the catalyst supporting hole and the communicating tube supporting hole are connected to the first wall. The notches are arranged in the Y direction in the central portion of the wall portion and are formed in the outer edge portion of the first wall portion from the outer circumferential side of the communication pipe to the outer circumferential side of the catalyst. The muffler according to claim 3, characterized in that: The muffler body has a substantially triangular cylindrical shape, the internal space has a substantially triangular cross-sectional shape, and the first wall portion has a substantially triangular cross-sectional shape to match the cross-sectional shape of the internal space. 5. The muffler according to claim 1, wherein the notch is formed at at least one corner of three corners of the first wall. The communication pipe communicates between the second chamber and the outside of the muffler body or between the second chamber and the other chamber in the muffler body, and the exhaust gas communicates with the outside of the muffler body. is introduced into the catalyst from the outside, flows from the catalyst into the first chamber, flows from the first chamber through the exhaust gas flow gap into the second chamber, and flows from the second chamber into the second chamber. The muffler according to any one of claims 1 to 5, wherein the flow flows through the communication pipe to the outside of the muffler body or to the other chamber within the muffler body.

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