Exhaust muffler for vehicle

Abstract

To provide an exhaust muffler for a vehicle capable of suppressing influence of assembly errors to mount an exhaust gas sensor.SOLUTION: An exhaust muffler 20 for a vehicle of the present disclosure comprises: an inner cylinder 32 in which a silencing space SP is formed; an outer cylinder 34 constituting an outer shell of the muffler 20; a pipe member 51 that is arranged in the silencing space SP, and through which exhaust gas G flows; a sensor 84 that detects a state of the exhaust gas G flowing through the pipe member 51; and a blockage body 88 that is arranged around the sensor 84, and blocks the outward flow of gas in the silencing space SP. The blockage body 88 has a pipe side connection portion 100 connected to the pipe member 51, and an outer cylinder side connection portion 102 connected to the outer cylinder 34.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] SUMMARY The present disclosure relates to a vehicle exhaust muffler having a sensor mounted thereon for detecting exhaust gases. [Background technology]

[0002] Some motorcycles are provided with a catalytic converter in an exhaust passage for purifying exhaust gas (see, for example, Patent Document 1). The motorcycle of Patent Document 1 is provided with exhaust gas sensors upstream and downstream of the catalytic converter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-110616 A Summary of the Invention [Problem to be solved by the invention]

[0004] When an exhaust gas sensor is provided in an exhaust muffler having an inner cylinder in which a sound absorbing space is formed and an outer cylinder that constitutes the outer shell of the muffler, assembly errors between the inner and outer cylinders can make it difficult to install the exhaust gas sensor.

[0005] The disclosure of the present application provides an exhaust muffler for a vehicle to which an exhaust gas sensor can be attached while reducing the effects of assembly errors. [Means for solving the problem]

[0006] The vehicle exhaust muffler of the present disclosure includes an inner tube in which a silencing space is formed, an outer tube constituting the outer shell of the muffler, a pipe member disposed in the silencing space through which exhaust gas flows, a sensor for detecting the state of exhaust gas flowing through the pipe member, and a blocking body disposed around the sensor for blocking the outward flow of gas in the silencing space. The blocking body has a pipe-side connection part connected to the pipe member and an outer-tube-side connection part connected to the outer tube. The sensor is a sensor for detecting components, temperature, flow rate, etc. of exhaust gas, for example, an oxygen sensor for detecting the amount of oxygen in exhaust gas. Effect of the Invention

[0007] According to the exhaust muffler for a saddle-type vehicle of the present disclosure, the blocking body is connected to the pipe member and the outer tube without the inner tube, so that the exhaust gas sensor can be attached without being affected by the assembly error of the muffler between the inner tube and the outer tube. Also, by connecting the pipe member and the outer tube via the blocking body, it is possible to eliminate the need for a structure for connecting the blocking body to the inner tube, which is larger than the pipe member, and it is possible to simplify the structure of the inner tube. [Brief description of the drawings]

[0008] [Figure 1] 1 is a side view showing a motorcycle, which is a type of saddle-ride type vehicle, equipped with an exhaust muffler according to a first embodiment of the present disclosure. [Diagram 2] FIG. [Diagram 3] FIG. 3 is a side view showing a state in which a muffler cover is removed from FIG. 2. [Figure 4] FIG. 2 is a vertical cross-sectional view showing the exhaust muffler. [Diagram 5] FIG. 2 is a horizontal cross-sectional view showing the exhaust muffler. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] 4 is a cross-sectional view showing a mounting structure of a downstream sensor of the exhaust muffler. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. In the following description, "front" and "rear" refer to the "front" and "rear" as seen from the traveling direction of the vehicle. In other words, the front-rear direction coincides with the longitudinal direction of the vehicle. "Left" and "right" refer to the "left" and "right" as seen from the driver who is in the vehicle. In other words, the "left-right direction" coincides with the width direction of the vehicle.

[0010] Fig. 1 is a side view showing a motorcycle, which is a type of saddle-type vehicle, equipped with an exhaust muffler according to a first embodiment of the present disclosure. The motorcycle in Fig. 1 is a vehicle for off-road driving. However, motorcycles are not limited to vehicles for off-road driving. In addition, the exhaust muffler of the present disclosure can also be applied to saddle-type vehicles other than motorcycles, such as three-wheeled vehicles, four-wheeled buggies, and small planing boats.

[0011] The body frame FR of this motorcycle has a main frame 1 that forms the front half, and a rear frame 2 that forms the rear half. The main frame 1 extends obliquely downward and rearward from a head pipe 4 at its front end. The main frame 1 curves downward at its rear end 1a and extends substantially downward.

[0012] The rear frame 2 has an upper rear frame piece 2a and a lower rear frame piece 2b. The upper rear frame piece 2a has its front end connected to the front and upper part of the rear end part 1a of the main frame 1, and extends rearward from the main frame 1. The lower rear frame piece 2b has its front end connected to a position slightly below the rear end part 1a of the main frame 1. The lower rear frame piece 2b extends diagonally upward and rearward from the main frame 1, and its rear end is connected to the rear part of the upper rear frame piece 2a.

[0013] A front fork 8 is rotatably supported by the head pipe 4 via a steering shaft (not shown). A steering handle 7 is fixed to the upper end of the front fork 8. A front wheel 10 is attached to the lower end of the front fork 8.

[0014] A swing arm bracket 9 is provided below the rear end portion 1a of the main frame 1. A swing arm 12 is supported around a pivot shaft 11 attached to the swing arm bracket 9 so as to be able to swing up and down freely. A rear wheel 14 is supported on the rear end portion of the swing arm 12.

[0015] An engine E, which is a drive source for the motorcycle, is disposed below and in front of the main frame 1 and attached to the main frame 1. The engine E drives the rear wheel 14 via a power transmission member (not shown) such as a drive chain. The engine E in this embodiment is a single-cylinder four-stroke engine E, but is not limited to this.

[0016] An intake port 16 is formed at the rear surface of the engine E, and an exhaust port 18 is formed at the front surface. A mixture of air and fuel introduced from the intake port 16 is burned in a combustion chamber and discharged from the exhaust port 18. An intake device ID is connected to the intake port 16. The intake device ID mixes the taken-in outside air with fuel to generate an air-fuel mixture, and supplies it to the intake port 16 of the engine E as intake air.

[0017] An exhaust pipe 22 is connected to the exhaust port 18. The exhaust pipe 22 extends rearward from the right side of the engine E and is connected to an exhaust muffler 20 disposed above the right side of the rear wheel 14. A part of the exhaust muffler 20, specifically the upper half, is covered from the outside by a muffler cover 24. The muffler cover 24 is disposed with a radial gap from the exhaust muffler 20. By covering the exhaust muffler 20 with the muffler cover 24, a driver in a riding position is prevented from directly contacting the exhaust muffler 20. The muffler cover 24 is made of, for example, sheet metal, and is detachably attached to the exhaust muffler 20. However, the arrangement of the exhaust pipe 22 and the exhaust muffler 20 is not limited to this. Details of the exhaust muffler 20 will be described later.

[0018] A fuel tank 25 is supported on the main frame 1. Fuel for the engine E is stored in the fuel tank 25. The fuel tank 25 is disposed above the engine E. Behind the fuel tank 25, a seat 26 for a driver to sit on is supported on the upper rear frame piece 2a.

[0019] [Exhaust muffler] The exhaust muffler 20 of the present disclosure will be described below. Fig. 2 is a side view of the exhaust muffler 20, Fig. 3 is a side view showing the state with the muffler cover 24 removed, Fig. 4 is a vertical cross-sectional view of the exhaust muffler 20, Fig. 5 is a horizontal cross-sectional view of the exhaust muffler 20, and Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 4. In the following description, "upstream" and "downstream" refer to "upstream" and "downstream" in the flow direction of the exhaust gas G, respectively.

[0020] The exhaust muffler 20 of the present disclosure has a silencing function that reduces exhaust noise. In addition, the exhaust muffler 20 has a so-called purification function that suppresses the emission of harmful substances contained in the exhaust gas into the atmosphere. Here, the "silencing function" refers to suppressing the pressure energy of the exhaust gas by forming multiple chambers that expand and contract repeatedly or by using a resonance structure. In addition, for example, platinum group elements (catalyst materials) such as platinum (Pt), palladium (Pd), and rhodium (Rh), which are rare precious metals, are used for the "purification function", and harmful substances contained in the exhaust gas are converted into harmless substances by an oxidation-reduction reaction between the platinum group elements and the exhaust gas. Specifically, by exposing the exhaust gas to a platinum-based element, nitrogen oxides (NO X ), carbon monoxide (CO), and hydrocarbons (CH) are converted into non-hazardous substances such as N 2 , CO 2 , H 2 Convert each to O.

[0021] The exhaust muffler 20 is a device that reduces exhaust noise from the engine E of the motorcycle and adjusts engine characteristics. As shown in Fig. 2, the exhaust muffler 20 is connected to the exhaust pipe 22 via a connecting pipe 27. The connecting pipe 27 is a pipe through which the exhaust gas G flows, and its upstream end (front end) is detachably connected to the exhaust pipe 22 by a band or the like, and its downstream end (rear end) is joined to the exhaust muffler 20 by welding. An upstream sensor 35 that detects the state of the exhaust gas G flowing through the connecting pipe 27 is attached to the downstream end of the connecting pipe 27. In this embodiment, the upstream sensor 35 is an oxygen sensor that detects the amount of oxygen in the exhaust gas G.

[0022] The exhaust muffler 20 has a cylindrical muffler main body 28 and a muffler inlet 30 connected to the connecting pipe 27 at an upstream end (front end) and connected to the muffler main body 28 at a downstream end (rear end). As shown in FIG. 3, an attachment portion 28a to which the muffler cover 24 (FIG. 2) is fastened is provided on the outer circumferential surface of the muffler main body 28. The attachment portion 28a in this embodiment is disposed to sandwich a downstream sensor described later. Specifically, the attachment portion 28a has a welded nut to which a fastening member such as a bolt is screwed. In this embodiment, two attachment portions 28a are provided spaced apart in the front-rear direction. However, the structure, arrangement, and number of the attachment portions 28a are not limited to those in the embodiment. In this embodiment, the muffler main body 28 is cylindrical with an elliptical cross section. The cross-sectional shape of the muffler main body is not limited to an elliptical shape, and may be a perfect circle or a substantially polygonal shape.

[0023] The muffler 20 has an outer cylinder 34 that constitutes the outer shell of the muffler 20. That is, the muffler body 28 has a double structure that includes an inner cylinder 32 and an outer cylinder 34 that covers the radial outside of the inner cylinder 32. In this embodiment, a sound absorbing material 36 is interposed between the inner cylinder 32 and the outer cylinder 34. The sound absorbing material 36 is realized by a porous material in which a large number of fine holes and gaps are formed. For example, glass wool is used as the sound absorbing material 36. Punching holes are formed in the peripheral wall of the inner cylinder 32, and the exhaust gas G in the sound silencing space SP comes into contact with the sound absorbing material 36 through the punching holes. By providing the sound absorbing material 36 in the exhaust muffler 20, it is possible to reduce the radiated sound of the exhaust gas G radiated from the outer cylinder 34. In addition, by forming an air layer by the sound absorbing material 36, it is possible to suppress the surface temperature of the outer cylinder 34 of the exhaust muffler 20 from increasing.

[0024] The muffler inlet portion 30 is a cone-shaped member whose diameter gradually increases from the upstream end connected to the connecting pipe 27 toward the downstream end connected to the muffler main body portion 28. In detail, the downstream end of the connecting pipe 27 is inserted into the inner circumferential surface of the upstream end of the muffler inlet portion 30 and joined by welding. The downstream end of the muffler inlet portion 30 is inserted into the inner circumferential surface of the upstream end of the muffler main body portion 28 and joined by welding. In this embodiment, the inside of the muffler inlet portion 30 also constitutes a part of the silencing space SP of the exhaust muffler 20. In other words, the front end of the silencing space SP is closed by the front end wall 30a of the muffler inlet portion 30.

[0025] The downstream end of the muffler inlet portion 30 is connected to the upstream end of the outer cylinder 34. The muffler inlet portion 30 accommodates the upstream portion of the pipe member in its internal space. The muffler inlet portion 30 has a double structure with the pipe member provided in the internal space. This prevents exhaust gas G from flowing directly from the connecting pipe 27 to the muffler inlet portion 30. The internal space of the muffler inlet portion 30 communicates with the internal space of the inner cylinder 32 at its downstream end. This allows the internal space of the muffler inlet portion 30 to function as a silencing space.

[0026] The silencing space SP of the exhaust muffler 20 may be divided into a plurality of silencing chambers. In this embodiment, the silencing space SP is divided into three, first to third silencing chambers 41, 42, and 43. In detail, the rear end of the silencing space SP is closed by the cover member 38, and the front end of the silencing space SP is closed by the muffler inlet portion 30. The silencing space SP is defined by a first partition wall 44 on the front side and a second partition wall 46 on the rear side. The cover member 38 is joined to the inner peripheral surface of the rear part of the outer cylinder 34 by welding, and the first and second partition walls 44, 46 are joined to the inner peripheral surface of the inner cylinder 32 by welding.

[0027] The silencing chambers 41, 42, 43 are arranged in the order of the second silencing chamber 42, the third silencing chamber 43, and the first silencing chamber 41 from the front. In detail, the first silencing chamber 41 is formed in the inner space of the inner cylinder 32 between the cover member 38 and the second partition wall 46, the second silencing chamber 42 is formed in the inner space of the inner cylinder 32 and the muffler inlet portion 30 by the first partition wall 44 and the front end wall 30a of the muffler inlet portion 30, and the third silencing chamber 43 is formed in the inner space of the inner cylinder 32 by the first partition wall 44 and the second partition wall 46.

[0028] Pipe members 51-53, through which exhaust gas G flows, are disposed in the silencing space SP of the exhaust muffler 20. The exhaust muffler 20 of the present embodiment includes three pipe members, namely, first to third pipe members 51-53.

[0029] The first pipe member 51 has an upstream end 51a communicating with the downstream end of the connecting pipe 27. The first pipe member 51 extends from the upstream end 51a to the downstream side in the flow direction, penetrates the first and second partition walls 44, 46, and has a downstream end 51b opening into the first silencing chamber 41. The first pipe member 51 will be described in detail later.

[0030] 5 has an upstream end 52a that opens into the first silencing chamber 41. The second pipe member 52 extends forward from the upstream end 52a, penetrates the second partition 46 and the first partition 44, and has a downstream end 52b that opens into the second silencing chamber 42. The first partition 44 is also provided with a through hole 54 (FIG. 4) that connects the second silencing chamber 42 and the third silencing chamber 43.

[0031] The third pipe member 53 has an introduction portion 53a that opens into the third silencing chamber 43. In this embodiment, the front end of the third pipe member 53 is closed, and the introduction portion 53a is formed on the outer circumferential surface of the third pipe member 53. The third pipe member 53 extends rearward through the second partition wall 46, and a downstream end 53b opens to the outside of the exhaust muffler 50. In this embodiment, the downstream end 53b of the third pipe member 53 communicates with an outlet pipe 56 that penetrates the cover member 38. The outer periphery of the outlet pipe 56 is covered by an outlet cover 58 that is detachably attached to the cover member 38.

[0032] The exhaust gas G that flows from the connecting pipe 27 into the first pipe member 51 of the exhaust muffler 20 flows inside the first pipe member 51 and is discharged to the first silencing chamber 41 where it expands. The exhaust gas G in the first silencing chamber 41 contracts as it flows through the second pipe member 52 and is discharged to the second silencing chamber 42 where it expands. The exhaust gas G in the second silencing chamber 42 contracts as it passes through the through hole 54 and flows into the third silencing chamber 43 where it expands. The exhaust gas G in the third silencing chamber 43 is discharged to the outside of the muffler via the third pipe member 53 and the outlet pipe 56.

[0033] In this way, the pressure energy of the exhaust gas G is consumed by repeated expansion and contraction within the exhaust muffler 20. This silences the exhaust gas G when it is discharged to the outside of the exhaust muffler 20. In addition, the second partition 46 may be provided with a through hole that communicates between the first silencing chamber 41 and the third silencing chamber 43, and exhaust interference (resonance) may occur between the exhaust gas G flowing from the second silencing chamber 42 to the third silencing chamber 43, thereby silencing the exhaust gas G.

[0034] [Flame arrester] In this embodiment, a flame arrester 60 is provided in the third pipe member 53. The flame arrester 60 blocks flames and allows only gas to pass through, and in this embodiment, is a wire mesh 60 attached to the introduction portion 53a of the third pipe member 53.

[0035] In this embodiment, the third pipe member 53 is provided detachably so as to enable maintenance of the flame arrestor 60. In detail, a flange member 66 expanding in diameter toward the rear is joined to a connecting member 64 that connects the third pipe member 53 and the outlet pipe 56. This flange member 66 and the cover member 38 are connected from the rear by bolts 70 in a state where they are stacked in the front-to-rear direction with the cover member 38 in front.

[0036] Further, an insertion tube 62 having a larger diameter than the third pipe member 53 is provided so as to penetrate the second partition wall 46. The small-diameter third pipe member 53 is inserted into the insertion tube 62 by loosening a bolt 70 so as to be movable in the front-rear direction. A seal member 69 is attached to the outer circumferential surface of the third pipe member 53 and adjacent to the inner circumferential surface of the insertion tube 62. The seal member 69 can prevent the exhaust gas G from flowing from the first silencing chamber 41 into the third silencing chamber 43 through a gap between the outer circumferential surface of the third pipe member 53 and the inner circumferential surface of the insertion tube 62.

[0037] However, the flame arrestor 60 does not have to be provided to the third pipe member 53. In this case, the insertion tube 62 is omitted, and the third pipe member 53 and the outlet pipe 56 can be joined to the second partition wall 46 and the cover member 38 by welding, respectively.

[0038] [Catalytic converter] A catalytic converter 72 is disposed in the first pipe member 51. The catalytic converter 72 purifies harmful exhaust components contained in the exhaust gas G. In detail, the first pipe member 51 has a large-diameter catalyst storage section 74 that stores the catalytic converter 72. The catalyst storage section 74 is the largest diameter portion of the first pipe member 51. The first pipe member 51 has an upstream section 76 upstream of the catalyst storage section 74. The first pipe member 51 also has a downstream section 80 downstream of the catalyst storage section 74.

[0039] An upstream portion 76 of the first pipe member 51, which is located upstream of the catalyst containing portion 74, communicates with the connecting pipe 27 at its upstream end. In other words, the upstream end of the upstream portion 76 constitutes the upstream end 51a of the first pipe member 51. The upstream portion 76 gradually increases in diameter from the upstream end 51a toward the catalyst containing portion 74.

[0040] The axes of the upstream section 76 and the catalyst storage section 74 are inclined radially outward relative to the outer cylinder 34 as they proceed rearward. The upstream section 76 is formed into a "bun-shaped structure" formed by joining upper and lower halves, resulting in an asymmetric shape between the top and bottom. The lower section of the upstream section 76 is formed so that the amount of expansion of its diameter as it proceeds downstream is smaller than that of the upper section of the upstream section 76. By forming the lower section of the upstream section 76 to have a gentle inclination in this way, it is possible to suppress the change in cross-sectional area in the flow direction, and thus suppress turbulence of the exhaust gas G.

[0041] An inlet pipe 75 is disposed inside the upstream portion 76. The inlet pipe 75 is joined to the inner peripheral surface of the upstream portion 76 by welding. A front end portion 75a of the inlet pipe 75 faces the connecting pipe 27. That is, the exhaust gas G from the connecting pipe 27 is introduced into the inlet pipe 75. A rear end portion 75b of the inlet pipe 75 is closed, and a plurality of punching holes 75c are formed in the peripheral wall of the inlet pipe 75. Therefore, the exhaust gas G introduced into the inlet pipe 75 is discharged in the radial direction from the punching holes 75c. That is, the inlet pipe 75 constitutes a deflection portion that directs the flow of the exhaust gas G in the radial direction on the upstream side of the catalytic converter 72.

[0042] The downstream portion 78 of the first pipe member 51 downstream of the catalyst storage portion 74 has a reduced diameter portion 80 whose diameter is reduced toward the downstream side, and an extension portion 82 connected to the downstream end of the reduced diameter portion 80. The reduced diameter portion 80 is formed in a "monaka structure" formed by joining upper and lower divided bodies, and is formed in an asymmetric shape from top to bottom. The upper portion of the reduced diameter portion 80 is formed so that the amount of expansion of the diameter is smaller as it proceeds downstream than the lower portion of the reduced diameter portion 80. In this way, the upper portion of the reduced diameter portion 80 is formed with a gentle slope, which makes it possible to suppress the change in cross-sectional area in the flow direction, and to suppress turbulence of the exhaust gas G. In addition, the upper portion of the reduced diameter portion 80 is formed with a gentle slope, in other words, flat, which makes it easier to connect it to a blocking body, which will be described later.

[0043] Specifically, the downstream portion 78 is disposed closer to the inner wall of the outer cylinder 34 than the upstream portion 76. More specifically, the reduced diameter portion 80 has a portion closer to the inner wall of the outer cylinder 34 extending along the outer cylinder 32, and a portion farther from the inner wall of the outer cylinder 34 inclined downstream in a direction radially approaching the outer cylinder 32. Therefore, the axis of the reduced diameter portion 80 as a whole is also inclined downstream in a direction radially approaching the inner wall of the outer cylinder.

[0044] The downstream section 78 has the largest diameter at the upstream end of the reduced diameter section 80. The downstream end of the reduced diameter section 80 and the extension section 82 connected to the downstream end have the same passage area. The extension section 82 extends downstream from the reduced diameter section 80 with a constant passage area. In other words, the extension section 82 extending along the outer tube 34 is formed downstream of the reduced diameter section 80 in the first pipe member 51. The downstream end of the extension section 82 opens to the second muffler chamber 42. That is, the downstream end of the downstream section 78 constitutes the downstream end 51b of the first pipe member 51. A straight section of a certain length is required downstream of the catalytic converter 72, and in this embodiment, the straight section is secured by the extension section 82. For example, the volume of the extension section 82 may be formed to be larger than the combustion volume of one cylinder. Also, the length of the extension section 82 may be formed to be longer than the diameter of the catalytic converter 72.

[0045] [Sensor] As shown in FIG. 4, a downstream sensor 84 is attached to the exhaust muffler 20. The downstream sensor 84 detects the state of the exhaust gas G flowing through the first pipe member 51. In this embodiment, the downstream sensor 84 is an oxygen sensor that detects the amount of oxygen in the exhaust gas G. As shown in FIG. 2, the downstream sensor 84 is covered from the outside by the muffler cover 24. This makes it possible to prevent the downstream sensor 84 from colliding with an obstacle. By covering the downstream sensor 84 with the muffler cover 24, a dedicated part for covering the downstream sensor 84 can be eliminated. In addition, an off-road vehicle such as that of this embodiment is prone to being covered with mud, water, and the like, but in this embodiment, the downstream sensor 84 is covered with the muffler cover 24 and is therefore protected from mud and water.

[0046] In this embodiment, as shown in Fig. 4, the upstream sensor 35 is disposed upstream of the catalytic converter 72, and the downstream sensor 84 is disposed downstream of the catalytic converter 72. The upstream sensor 35 is used, for example, for fuel injection control (air-fuel ratio control). The downstream sensor 84 is used, for example, for fault diagnosis of the catalytic converter 72.

[0047] The downstream sensor 84 is inserted into the reduced diameter portion 80 of the first pipe member 51. More specifically, the downstream sensor 84 is inserted into a pipe portion downstream of the downstream end of the catalyst containing portion 74 and having a smaller diameter than the catalyst containing portion 74. In this embodiment, the insertion portion 86 into which the downstream sensor 84 is inserted in the first pipe member 51 is the portion closest to the inner tube 32 and the outer tube 34 in the first pipe member 51, and has a smaller diameter than the catalyst containing portion 74. In other words, the downstream sensor 84 is disposed at a position where the passage area is narrowed downstream of the catalytic converter 72. In this way, by disposing the downstream sensor 84 in the area where the exhaust gas G is collected downstream of the catalytic converter 72, the exhaust gas G collected in the radial direction can be brought into contact with the sensor, and the detection variation can be suppressed.

[0048] Moreover, the passage area is narrowed toward the side where the downstream sensor 84 is inserted. In detail, the axis X1 of the downstream section 78 is inclined toward the downstream side with respect to the axis AX of the exhaust muffler 22 so as to approach the downstream sensor 84. Moreover, the center point O1 of the insertion portion 86 is located radially outward of the center point of the outer cylinder 34 (the axis AX of the exhaust muffler 22).

[0049] [Downstream sensor mounting structure] Next, the mounting structure of the downstream sensor 84 will be described with reference to FIG. 7. The downstream sensor 84 is formed in an axial shape. A detection portion is provided at one axial end of the downstream sensor 84. The detection portion of the downstream sensor 84 passes through the outer tube 34 and the inner tube 32 of the exhaust muffler 20 and is disposed in the reduced diameter portion 80 of the first pipe member 51. The downstream sensor 84 is attached to the reduced diameter portion 80 with the detection portion disposed in the internal space of the reduced diameter portion 80. In detail, the detection portion of the downstream sensor 84 passes through a muffler opening 90 formed in the outer tube 34 of the exhaust muffler 20 and is attached to a pipe opening 92 formed in the insertion portion 86 of the first pipe member 51. In more detail, the downstream sensor 84 is screwed into a cylindrical boss portion 94 joined to the pipe opening 92 by welding.

[0050] A radial gap is formed between the extension portion 82 and the inner cylinder 32. The exhaust gas G may pass through the gap and head toward an opening for inserting a sensor formed in the inner cylinder 32. In this embodiment, even if the exhaust gas G flows out of the inner cylinder 32 from the opening of the inner cylinder 32, the exhaust gas G is prevented from flowing out from the vicinity of the sensor 84 by being blocked by the outer cylinder 34 and a blocking body 88 (described later).

[0051] An opening through which the detection portion of the downstream sensor 84 is inserted is also formed in the inner cylinder 32. The inner cylinder 32 has an opening large enough to accommodate the obstruction body 88 (described later). In other words, an opening larger than the welded region of the obstruction body 88 (described later) to the first pipe member 51 is formed.

[0052] The exhaust muffler 20 includes a blocking body 88 that blocks the muffler opening 90 of the outer cylinder 34. As shown in Fig. 3, the blocking body 88 is disposed around the downstream sensor 84 and blocks the exhaust gas G in the silencing space SP from flowing outward. The blocking body 88 in this embodiment is formed by bending a metal plate, and has an elliptical shape with a major axis in the longitudinal direction D1 of the exhaust muffler 20 when viewed from the direction of the axis X2 of the downstream sensor 84. In this embodiment, the blocking body 88 is made of a metal material, but the material and shape are not limited to those in this embodiment as long as the blocking body 88 has a structure that blocks the opening formed for inserting the sensor.

[0053] The blocking body 88 has a recess 96 at its center that recesses toward the sound deadening space SP. In detail, the blocking body 88 has an inclined surface 98 that gradually recesses from its outer edge toward its center, and the inclined surface 98 is connected to the recess 96. The amount of recession of the blocking body 88 from the outer tube 34 is not constant, but varies depending on its circumferential position. In this embodiment, when the blocking body 88 is attached to the vehicle, the amount of recession of the blocking body 88 from the outer tube 34 decreases toward the outside in the vehicle width direction (the right side in this embodiment). This makes it possible to prevent water from accumulating in the recess 96 when the vehicle is upright on the side stand.

[0054] 6, the obstruction body 88 has a pipe side connection part 100 connected to the first pipe member 51, and an outer tube side connection part 102 connected to the outer tube 34. In other words, the obstruction body 88 is connected to the first pipe member 51 which is the innermost in the radial direction, and the outer tube 34 which is the outermost in the radial direction, but is not connected to the inner tube 32 which is in between.

[0055] The pipe side connection part 100 is connected to a portion of the first pipe member 51 adjacent to the pipe opening 92 in a radially overlapping manner. On the other hand, the outer tube side connection part 102 is connected to a portion of the outer tube 34 adjacent to the muffler opening 90 in a radially overlapping manner. In other words, the outer tube side connection part 102 constitutes a first member 102 connected to a portion adjacent to the muffler opening 90 in a radially overlapping manner, and the pipe side connection part 100 constitutes a second member connected to a portion adjacent to the pipe opening 92 in a radially overlapping manner.

[0056] In this embodiment, the obstruction body 88 is processed by bending a single piece of sheet metal, but the outer tube side connection part (first member) 102 and the pipe side connection part (second member) 100 may be constructed as separate bodies and connected at the part where they overlap in the axial direction.

[0057] The insertion portion 86 of the first pipe member 51, i.e., the portion where the pipe opening 92 is formed, has a flat surface perpendicular to the axis X2 of the downstream sensor 84. The pipe side connection portion 100 has a plane along this flat surface, and is joined by welding with the flat surface of the first pipe member 51 and the flat surface of the pipe side connection portion 100 overlapping in the radial direction. At this time, the first pipe member 51 and the pipe side connection portion 100 of the obstruction body 88 can move relatively in the direction along the flat surface and the plane, so that deviation in the axial direction (the direction perpendicular to the paper surface of FIG. 6) is absorbed. In other words, the pipe side connection portion 100 functions as a joint margin in the axial direction when joining.

[0058] The outer tube side connection part 102 is formed by bending the outer end of the blocking body 88 radially inward and extending toward the silencing space SP. In this embodiment, the outer tube side connection part 102 is connected to the outer tube 34 via a connection member 104. The connection member 104 is formed by bending a metal plate so that its cross-sectional shape is V-shaped.

[0059] One side portion 104a of the connecting member 104 bent into a V-shape is joined to the outer circumferential surface of the outer tube 34 by welding. In detail, the one side portion 104a extends in the circumferential direction along the outer circumferential surface of the outer tube 34, and the one side portion 104a and the outer circumferential surface of the outer tube 34 are joined by welding in a state where they are overlapped in the radial direction. At this time, the one side portion 104a of the connecting member 104 and the outer tube 34 are relatively movable in the circumferential direction, so that deviation in the circumferential direction is absorbed. In other words, the one side portion 104a of the connecting member 104 functions as a circumferential joint margin at the time of joining.

[0060] The other side portion 104b of the connecting member 104 bent into a V-shape is joined to the outer tube side connecting portion 102 of the blocking body 88 by welding. In detail, the other side portion 104b extends radially toward the silencing space SP, and the other side portion 104b and the outer tube side connecting portion 102 extending radially are joined by welding in a state where they are overlapped in the circumferential direction. At this time, the other side portion 104b of the connecting member 104 and the outer tube side connecting portion 102 of the blocking body 88 are relatively movable in the radial direction, so that radial deviation is absorbed. In other words, the other side portion 104b of the outer tube side connecting portion 102 functions as a radial joint margin at the time of joining.

[0061] The blocking body 88 is not limited to the structure of this embodiment as long as it is configured to absorb radial, circumferential and axial misalignment between the outer tube 34 and the first pipe member 51 .

[0062] 4, a restricting wall 106 is provided near a portion between the inner cylinder 32 and the outer cylinder 34 where the downstream sensor 84 is attached. The restricting wall 106 is a member having an L-shaped cross section, and restricts the filler 36 from moving toward the muffler opening 90. The restricting wall 106 is provided along the downstream sensor 84, i.e., along the muffler opening 90, and prevents the filler 36 between the inner cylinder 32 and the outer cylinder 34 from shifting toward the muffler opening 90.

[0063] As shown in FIG. 7, the blocking body 88 is welded to the first pipe member 51 at a welded portion W1. The blocking body 88 is also welded to the outer tube 34 at a welded portion W2. The first pipe member 51 and the outer tube 34 are welded all around and sealed with the blocking body 88, thereby preventing the gas in the silencing space SP from leaking outward. The inner tube 32 is not welded to the blocking body 88, and there may be a gap between the blocking body 88 and the inner tube 32. Such a gap allows assembly errors to be absorbed. The catalytic converter 74 and the first pipe member 51 may have a sliding structure.

[0064] According to the above configuration, the blocking body 88 is connected to the first pipe member 51 and the outer cylinder 34 without the inner cylinder 32, so that the downstream sensor 84 can be attached by absorbing assembly errors between the inner cylinder 32 and the outer cylinder 34 of the exhaust muffler 20 and the thermal expansion difference between the inner cylinder 32 and the outer cylinder 34. In detail, even if an assembly error occurs when joining the inner cylinder 32 and the outer cylinder 34, the relative position between the first pipe member 51 and the outer cylinder 34 can be adjusted by the joint margin provided in the blocking body 88. As a result, the downstream sensor 84 can be stably attached to the double-structure exhaust muffler 22.

[0065] Also, by connecting the first pipe member 51 and the outer cylinder 34 with the blocking body 88, it is possible to eliminate the need for a structure for connecting the blocking body 88 to the inner cylinder 32, which is larger than the first pipe member 51, and it is possible to simplify the structure of the inner cylinder 32. Furthermore, by attaching the downstream sensor 84 to the first pipe member 51 and detecting the state of the exhaust gas G flowing through the first pipe member 51, it is possible to prevent the flow of the exhaust gas G from being disturbed and improve the detection accuracy compared to the case where the downstream sensor 84 is provided in the inner cylinder 32.

[0066] 4, in this embodiment, the axis AX2 of the insertion portion 86 of the first pipe member 51, into which the downstream sensor 84 is inserted, is located radially outward of the axis AX of the outer cylinder 34. According to this configuration, the first pipe member 51 can be disposed close to the circumferential surface of the outer cylinder 34, and the insertion amount of the downstream sensor 84 from the outer cylinder can be reduced.

[0067] 6, the blocking body 88 has a first member (outer cylinder side connection portion) 102 that is connected to a portion of the outer cylinder 32 adjacent to the muffler opening 90 while overlapping in the circumferential direction, and a second member (pipe side connection portion) 100 that is connected to a portion of the first pipe member 51 adjacent to the pipe opening 92 while overlapping in the radial direction. According to this configuration, the outer cylinder side connection portion 102 functions as a radial joint margin, and the pipe side connection portion 100 functions as an axial joint margin.

[0068] In addition, in this embodiment, the obstruction body 88 is formed in a structure in which it is overlapped in the radial direction on the circumferential surfaces of the first pipe member 51 and the outer tube 34. Alternatively, for example, a structure in which ribs protruding in the axial direction are formed on the first pipe member 51 and the outer tube 34 and the obstruction body 88 is overlapped in the axial direction on the protruding rib may be used. However, by forming the obstruction body 88 in a structure in which it is overlapped in the radial direction as in this embodiment, it is not necessary to form a rib portion protruding in the radial direction on the outer tube 34 and the first pipe member 51, and the structure of the outer tube 34 and the first pipe member 51 can be easily simplified.

[0069] 4, in the first pipe member 51, a portion upstream of the insertion portion 86 into which the downstream sensor 84 is inserted has its axis X1 inclined radially toward the insertion portion 86 in a direction approaching the opening 102 of the outer cylinder 32. According to this configuration, the first pipe member 51 can be disposed close to the outer cylinder 34, and the insertion amount of the downstream sensor 84 from the outer cylinder 34 can be reduced.

[0070] In the present embodiment, an insertion portion 86 of the first pipe member 51, into which the downstream sensor 84 is inserted, has a smaller diameter than the inlet portion 76 of the first pipe member 51. According to this configuration, the exhaust gas G in the first pipe member 51 can be concentrated near the downstream sensor 84, and the detection accuracy can be improved.

[0071] In this embodiment, an extension portion 82 extending in the direction of the axis AX of the exhaust muffler 20 is formed downstream of an insertion portion 86 into which a downstream sensor 84 is inserted in the first pipe member 51. With this configuration, the outlet 51b of the first pipe member 51 and the insertion portion 86 can be separated, and exhaust gas G that flows back from the outlet 51b due to exhaust pulsation can be prevented from reaching the downstream sensor 84, thereby improving detection accuracy.

[0072] In this embodiment, the catalytic converter 72 is disposed upstream of an insertion portion 86 into which the downstream sensor 84 is inserted in the first pipe member 51. With this configuration, the catalytic converter 72 and the downstream sensor 84 can be supported by the common first pipe member 51.

[0073] In this embodiment, a deflection portion 75 that directs the flow of exhaust gas G in a radial direction is provided on the upstream side of the catalytic converter 72 in the first pipe member 51. According to this configuration, the exhaust gas G is prevented from directly colliding with the catalytic converter 72, and the catalytic converter 72 is protected.

[0074] In this embodiment, the silencing space SP is smaller by the amount of the catalytic converter 72, but the inside of the muffler inlet 30 upstream of the muffler main body 28 is also used as the silencing space SP, and a part of the catalytic converter 72 is disposed in the muffler inlet 30. Furthermore, an inlet pipe 75 having punched holes 75c is disposed upstream of the catalytic converter 72 inside the muffler inlet 30 to diffuse the exhaust gas G in the radial direction. This ensures the silencing space SP, and the exhaust gas G is diffused and flows evenly into the catalytic converter 72.

[0075] In this embodiment, when the obstruction body 88 is attached to the vehicle body shown in Fig. 3, the amount of recession of the obstruction body 88 from the outer tube 34 decreases toward one side in the vehicle width direction. With this configuration, it is possible to prevent water from accumulating in the recess 96 when the vehicle is upright on the side stand.

[0076] In this embodiment, a muffler cover 24 is provided to cover at least a portion of the outer cylinder 34 from the outside, and the downstream sensor 84 is covered from the outside by the muffler cover 24. According to this configuration, since the downstream sensor 84 is covered by the muffler cover 24, there is no need to provide a dedicated part for protecting the downstream sensor 84, so the downstream sensor 84 can be protected and the number of parts can be reduced.

[0077] 4, the sound absorbing material 36 is filled between the inner tube 32 and the outer tube 34, and a restricting wall 106 that restricts the movement of the sound absorbing material 36 is provided near the attachment portion of the downstream sensor 84. With this configuration, the restricting wall 106 can prevent the sound absorbing material 36 from becoming displaced due to the formation of an opening in the inner tube 32.

[0078] The number and position of the catalytic converters 72 are not limited to those in the above embodiment. In the above embodiment, only one catalytic converter 72 is provided and is disposed inside the exhaust muffler 20, but there may be two or more catalytic converters 72, at least one of which may be provided outside the muffler. In addition, the catalytic converter 72 does not have to be disposed inside the exhaust muffler 20.

[0079] As a modified example, the blocking body 88 may be non-circular, for example, rectangular. Also, the blocking body 88 may penetrate inside the first pipe member 51. Furthermore, the first pipe member 51 may also have a "monaka structure" split into upper and lower parts. Also, instead of a boss for fixing a sensor being fixed to the first pipe member 51, a boss for fixing a sensor may be formed on the blocking body 88A side. Even in this case, the blocking body 88A and the first pipe member 51 are welded all around to prevent the outflow of exhaust gas G.

[0080] The vehicle exhaust muffler of the present disclosure includes the following aspects 1 to 11. [Aspect 1] An inner cylinder in which a sound-absorbing space is formed; An outer tube that constitutes the outer shell of the muffler; a pipe member disposed in the silencing space and through which exhaust gas flows; A sensor that detects a state of exhaust gas flowing through the pipe member; a blocking body disposed around the sensor to block outflow of gas from within the sound absorbing space; Equipped with The obstruction body is an exhaust muffler for a saddle-type vehicle, the obstruction body having a pipe-side connection portion connected to the pipe member, and an outer cylinder-side connection portion connected to the outer cylinder. [Aspect 2] In the vehicle exhaust muffler according to aspect 1, the axis of the insertion portion of the pipe member into which the sensor is inserted is located radially outward from the axis of the outer cylinder. [Aspect 3] In the vehicle exhaust muffler according to the first or second aspect, the obstruction body is a first member that is connected to a portion of the outer cylinder adjacent to the opening in a circumferential direction and overlaps the first member; a second member that is radially overlapped and connected to a portion of the pipe member adjacent to the opening, An exhaust muffler for a vehicle, wherein the first member and the second member are connected to each other at an axially overlapping portion. [Aspect 4] In a vehicle exhaust muffler described in any one of aspects 1 to 3, a portion of the pipe member upstream of the insertion portion into which the sensor is inserted has an axis that is inclined radially toward the insertion portion in a direction approaching the opening of the outer tube. [Aspect 5] In the vehicle exhaust muffler according to any one of aspects 1 to 4, an insertion portion of the pipe member into which the sensor is inserted has a smaller diameter than an inlet of the pipe member. [Aspect 6] In the vehicle exhaust muffler described in any one of aspects 1 to 5, an extension portion is formed that extends downstream of an insertion portion of the pipe member into which the sensor is inserted. [Aspect 7] In the vehicle exhaust muffler according to any one of the first to sixth aspects, a catalytic converter is disposed upstream of an insertion portion of the pipe member into which the sensor is inserted. [Aspect 8] In the vehicle exhaust muffler according to aspect 7, a deflection portion that directs the flow of exhaust gas radially is provided on the pipe member upstream of the catalytic converter. [Aspect 9] In a vehicle exhaust muffler described in any one of aspects 1 to 8, when attached to a vehicle, the obstruction body has a recession amount from the outer tube that becomes smaller toward one side in the width direction of the vehicle. [Aspect 10] The vehicle exhaust muffler according to any one of the first to ninth aspects further includes a muffler cover that covers at least a portion of the outer cylinder from the outside, An exhaust muffler for a vehicle, wherein the sensor is covered from the outside by the muffler cover. [Aspect 11] The vehicle exhaust muffler of any one of the first to tenth aspects, further comprising: A sound absorbing material filled between the inner cylinder and the outer cylinder; a restricting wall provided near an attachment portion of the sensor to restrict movement of the sound absorbing material; A vehicle exhaust muffler comprising:

[0081] The present disclosure is not limited to the above-mentioned embodiments, and various additions, modifications, or deletions are possible within the scope of the gist of the present disclosure. For example, in the above-mentioned embodiment, an oxygen sensor that detects the amount of oxygen in the exhaust gas is used as the exhaust gas sensor, but the present disclosure is not limited to this, and may be, for example, a temperature sensor that detects the temperature of the exhaust gas, a flow velocity sensor that detects the flow velocity of the exhaust gas, a pressure sensor that detects the pressure of the exhaust gas, or the like.

[0082] In the above embodiment, an example has been described in which the downstream sensor 84 is disposed inside the exhaust muffler 22, but when the upstream sensor 35 is disposed inside the exhaust muffler 22, the above-mentioned structure can be applied as a fixing structure for the upstream sensor 35. In addition, the same can be applied to other sensors, for example structures, other than the exhaust gas sensor.

[0083] The vehicle on which the exhaust muffler of the present disclosure is mounted may be, but is not limited to, a relatively small saddle-type vehicle in which a driver straddles a seat. For example, the vehicle may be applied to a four-wheeled vehicle in which passengers ride side by side in the width direction. The exhaust muffler of the present disclosure may also be applied to a hybrid vehicle having an internal combustion engine and an electric motor. The exhaust muffler of the present disclosure is preferably applicable to a vehicle in which at least a portion of the outer cylinder is exposed to the outside among mufflers.

[0084] The exhaust muffler of the present disclosure can be applied to a double-structure exhaust muffler having an inner tube and an outer tube. In other words, the exhaust muffler of the present disclosure can be applied to a triple-structure exhaust muffler having a pipe member, an inner tube, and an outer tube. Therefore, the muffler layout for the vehicle is not limited. The exhaust muffler may be disposed on one of the vehicle width direction outer sides of the rear wheel, or on both vehicle width direction outer sides of the rear wheel. In addition, the exhaust muffler may be disposed directly above the rear wheel, or may be disposed between the rear wheel and the engine as an exhaust chamber. As for the structure partitioned in the muffler chamber, the above embodiment is only one example, and it is sufficient to have a triple structure of an outer tube, an inner tube, and a pipe member, and other existing structures may be used. Therefore, such structures are also included in the scope of the present disclosure. [Explanation of symbols]

[0085] 20 Exhaust muffler 24 Muffler cover 32 Inner cylinder 34 Outer cylinder 36 Filling material 51 First pipe member 72 Catalytic converter 75 Inlet pipe (deflection part) 82 Extension part 84 Downstream sensor (sensor) 86 Insertion 88 Obstruction body 90 Muffler opening (opening of outer cylinder) 92 Pipe opening (opening in pipe component) 100 Pipe side connection part (second member) 102 Outer tube side connection part (first member) 106 Regulatory Wall G. Exhaust gas SP sound deadening space

Claims

1. An inner cylinder in which a sound-absorbing space is formed; An outer tube that constitutes the outer shell of the muffler; a pipe member disposed in the silencing space and through which exhaust gas flows; A sensor that detects a state of exhaust gas flowing through the pipe member; a blocking body disposed around the sensor to block outflow of gas from within the sound absorbing space; Equipped with The obstruction body is an exhaust muffler for a vehicle having a pipe side connection portion connected to the pipe member and an outer cylinder side connection portion connected to the outer cylinder.

2. 2. The vehicle exhaust muffler according to claim 1, wherein an axis of the pipe member at an insertion portion into which the sensor is inserted is located radially outwardly of an axis of the outer cylinder.

3. 3. The vehicle exhaust muffler according to claim 1, wherein the obstruction is a first member connected to a portion of the outer cylinder adjacent to the opening in a circumferential direction; a second member connected to the portion of the pipe member adjacent to the opening in a radial direction and overlapping the second member; An exhaust muffler for a vehicle, wherein the first member and the second member are connected to each other at an axially overlapping portion.

4. 3. A vehicle exhaust muffler as described in claim 1 or 2, wherein a portion of the pipe member upstream of an insertion portion into which the sensor is inserted has an axis that is inclined radially toward the insertion portion in a direction approaching the opening of the outer tube.

5. 3. The vehicle exhaust muffler according to claim 1, wherein an insertion portion of said pipe member into which said sensor is inserted has a diameter smaller than an inlet of said pipe member.

6. 3. The vehicle exhaust muffler according to claim 1, wherein the pipe member has an extension portion extending downstream of an insertion portion into which the sensor is inserted.

7. 3. The vehicle exhaust muffler according to claim 1, wherein a catalytic converter is disposed upstream of an insertion portion of said pipe member into which said sensor is inserted.

8. 8. The vehicle exhaust muffler according to claim 7, wherein a deflection portion for directing the flow of exhaust gas in a radial direction is provided on the pipe member upstream of the catalytic converter.

9. 3. The vehicle exhaust muffler according to claim 1, wherein, when the muffler is attached to the vehicle, the amount of recess of the obstruction body from the outer cylinder decreases toward one side in the width direction of the vehicle.

10. 3. The vehicle exhaust muffler according to claim 1, further comprising a muffler cover that covers at least a portion of the outer cylinder from the outside, An exhaust muffler for a vehicle, wherein the sensor is covered from the outside by the muffler cover.

11. 3. The vehicle exhaust muffler according to claim 1 or 2, further comprising: A filler material filled between the inner cylinder and the outer cylinder; a restricting wall provided near an attachment portion of the sensor to restrict movement of the filler; A vehicle exhaust muffler comprising:

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