muffler

Abstract

To provide a muffler capable of simplifying assembling work.SOLUTION: The silencing device 20 of the present disclosure includes the outer shell member 31 in which the silencing space SP is formed, and the internal pipe 51 disposed in the silencing space SP. An outer shell opening 60 is formed in the peripheral wall of the outer shell member 31, and a pipe opening 68 is formed in the peripheral wall of the internal pipe 51. The internal pipe 51 has a cylindrical protruding portion 69 protruding radially outward from the peripheral wall. The protruding portion 69 is provided around the axis of the pipe opening 68. The oxygen sensor 64 is disposed so as to close the pipe opening 68. The muffling device 20 further includes a cap 72 that covers the shell opening 66. The cap 72 is joined to a peripheral portion of the outer shell opening 66 in the outer shell member 31 and the protrusion 69 of the internal pipe 51. The outside diameter d1 of the projection 69 is set to be smaller than the inside diameter d2 of the outer shell member 31.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a silencer that silences engine exhaust gases. [Background technology]

[0002] For example, engines used as a driving source for vehicles such as motorcycles are provided with a silencer that silences noise while purifying exhaust gas (see, for example, Patent Document 1). The silencer in Patent Document 1 includes a casing with a silencer chamber formed therein, and a pipe member that is disposed within the silencer chamber and through which exhaust gas flows, and is provided with an exhaust gas sensor that detects the oxygen concentration of the exhaust gas flowing inside the pipe member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-110616 Summary of the Invention [Problem to be solved by the invention]

[0004] In a silencer such as that described in Patent Document 1, the exhaust gas sensor penetrates both the casing and the pipe member in the radial direction. Therefore, assembly errors between the casing and the pipe member may make it difficult to install the exhaust gas sensor, raising concerns that the assembly work may become more complicated.

[0005] The disclosure of the present application provides a silencer that can simplify assembly work. [Means for solving the problem]

[0006] The silencer of the present disclosure is a silencer that silences engine exhaust gas, an outer shell member having a sound-absorbing chamber formed therein and an outer shell opening formed in a part of a peripheral wall thereof so as to penetrate in a radial direction; an internal pipe disposed in the silencing chamber, the internal pipe radially penetrating a portion of the peripheral wall, the internal pipe having a pipe opening facing the outer shell opening, and the internal pipe having a cylindrical protruding portion that goes around the pipe opening around its axis and protrudes radially relative to the remaining portion; an internal component disposed to close the pipe opening; a cap that is joined to a peripheral portion of the outer shell member around the outer shell opening and to the protruding portion of the internal pipe to cover the outer shell opening, The outer diameter of the protrusion is set smaller than the inner diameter of the outer shell member. Here, "the pipe opening faces the outer shell opening" means that the axis of the pipe opening of the inner pipe passes through the outer shell opening of the outer shell member. [Effects of the Invention]

[0007] According to the silencer for a saddle-ride type vehicle of the present disclosure, by using a cap separate from the outer shell member and the internal pipe, it is possible to absorb assembly errors between the outer shell member and the internal pipe and prevent exhaust gas from leaking from the silencer chamber through the shell opening. Furthermore, the outer diameter of the protruding portion of the internal pipe is formed smaller than the inner diameter of the outer shell member. This prevents the protruding portion from getting caught during the assembly process of the silencer, allowing the internal pipe with the protruding portion to be inserted axially into the outer shell member. Therefore, the assembly process can be simplified compared to when the protruding portion is formed after the internal pipe body, before the protruding portion, is inserted into the outer shell member. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view showing a motorcycle equipped with a silencer according to a first embodiment of the present disclosure. [Figure 2] FIG. [Figure 3] FIG. 3 is a side view showing a state in which the silencer cover is removed from FIG. 2. [Figure 4] FIG. 2 is a vertical cross-sectional view showing the silencer. [Figure 5]FIG. 5 is an enlarged longitudinal sectional view showing a sensor mounting portion of FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will be described below with reference to the drawings. In the following description, "front" and "rear" refer to the "front" and "rear" as seen from the direction of travel of the vehicle. In other words, the front-to-rear direction coincides with the longitudinal direction of the vehicle. "Left" and "right" refer to the "left" and "right" as seen from the driver's perspective while seated in the vehicle. In other words, the "left-to-right direction" coincides with the width direction of the vehicle. In the vehicle width direction, the inner side in the vehicle width direction refers to the side facing the vehicle body centerline extending in the front-to-rear direction, and the outer side in the vehicle width direction refers to the side facing away from the vehicle body centerline.

[0010] Fig. 1 is a side view showing a motorcycle equipped with a silencer 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. The silencer according to the present disclosure can also be applied to vehicles other than motorcycles, such as tricycles, four-wheeled buggies, and small personal watercraft. The silencer according to the present disclosure can also be applied to engines other than the drive source of vehicles.

[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 almost downward.

[0012] The rear frame 2 has an upper rear frame piece 2a and a lower rear frame piece 2b. The front end of the upper rear frame piece 2a is 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 front end of the lower rear frame piece 2b is 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 on 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 1a of the main frame 1. A swing arm 12 is journaled 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 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 on the rear surface of the engine E, and an exhaust port 18 is formed on the front surface. The mixture of air and fuel introduced through the intake port 16 is burned in the 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, which is then supplied 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 on the right side of the engine E and is connected to an exhaust muffler 20 that is located above and to the right of the rear wheel 14. The exhaust muffler 20 is a type of silencer that silences exhaust gases from the engine E.

[0018] A portion of the exhaust muffler 20, specifically the upper half thereof, 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. Covering the exhaust muffler 20 with the muffler cover 24 prevents the rider in a riding position 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.

[0019] A fuel tank 25 is supported on the main frame 1. The fuel tank 25 stores fuel for the engine E. The fuel tank 25 is disposed above the engine E. Behind the fuel tank 25, a seat 26 on which a driver sits is supported on the upper rear frame piece 2a.

[0020] [Exhaust muffler] The following describes exhaust muffler 20, which is one type of silencer of the present disclosure. Fig. 2 is a side view of exhaust muffler 20, Fig. 3 is a side view showing the state with muffler cover 24 removed, and Fig. 4 is a vertical cross-sectional view of exhaust muffler 20. In the following description, "upstream" and "downstream" refer to "upstream" and "downstream" in the flow direction of exhaust gas G, respectively.

[0021] The exhaust muffler 20 of the present disclosure has a silencing function that reduces exhaust noise. The exhaust muffler 20 also has a so-called purification function that suppresses the atmospheric emission of harmful substances contained in exhaust gas. Here, the "silencing function" refers to the suppression of exhaust pressure energy by forming multiple chambers that repeatedly expand and contract, or by using a resonant structure.

[0022] For the "purification function," platinum group elements (catalytic materials) such as rare precious metals platinum (Pt), palladium (Pd), and rhodium (Rh) are used, and harmful substances contained in the exhaust gas are converted into harmless substances through an oxidation-reduction reaction between the platinum group elements and the exhaust gas. Specifically, by exposing the exhaust gas to platinum group elements, harmful substances contained in the exhaust gas, such as nitrogen oxides (NO X), carbon monoxide (CO), and hydrocarbons (CH) are converted into harmless substances N2, CO2, and H2O, respectively.

[0023] 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.

[0024] The exhaust muffler 20 has a cylindrical muffler main body 28 and a muffler inlet 30 that is connected to the connecting pipe 27 at its upstream end (front end) and continues to the muffler main body 28 at its downstream end (rear end). A silencing space SP is formed inside the muffler main body 28 and the muffler inlet 30. In other words, the muffler main body 28 and the muffler inlet 30 form an outer shell member 31 of the exhaust muffler 20.

[0025] As shown in FIG. 3, the muffler main body 28 has an outer peripheral surface provided with mounting portions 28a to which the muffler cover 24 (FIG. 2) is fastened. The mounting portions 28a in this embodiment are arranged to sandwich a downstream sensor, which will be described later. Specifically, the mounting portions 28a have weld nuts onto which fastening members such as bolts are threadedly engaged. In this embodiment, two mounting portions 28a are provided spaced apart in the front-rear direction. However, the structure, arrangement, and number of the mounting portions 28a are not limited to those in the embodiment. In this embodiment, the muffler main body 28 is tubular 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.

[0026] The muffler main body 28 has an inner cylinder 32 in which a silencing space SP is formed, and an outer cylinder 34 disposed radially outside the inner cylinder 32. In other words, the muffler main body 28 has a double structure having the inner cylinder 32 and the outer cylinder 34 covering the radially outside of the inner cylinder 32.

[0027] In this embodiment, a sound-absorbing material 36 is interposed between the inner tube 32 and the outer tube 34. The sound-absorbing material 36 is, for example, glass wool. However, the sound-absorbing material 36 is not limited to this. Punched holes are formed in the peripheral wall of the inner tube 32, and the exhaust gas G in the silencing space SP comes into contact with the sound-absorbing material 36 through the punched holes. By providing the sound-absorbing material 36 in the exhaust muffler 20, it is possible to reduce the sound radiated from the outer tube 34 of the exhaust gas G. In addition, an air layer is formed by the sound-absorbing material 36, which makes it possible to suppress an increase in the surface temperature of the outer tube 34 of the exhaust muffler 20.

[0028] The muffler inlet portion 30 is a cone-shaped member whose diameter gradually increases from its upstream end connected to the connecting pipe 27 toward its downstream end connected to the muffler main body 28. Specifically, 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 upstream end of the muffler main body 28, specifically, into the inner circumferential surface of the upstream end of the outer cylinder 34, and joined by welding.

[0029] The silencing space SP of the exhaust muffler 20 may be divided into a plurality of silencing chambers. As shown in Fig. 4, in this embodiment, the silencing space SP is divided into three silencing chambers, namely, first to third silencing chambers 41, 42, and 43. More specifically, the rear end of the silencing space SP is closed by a lid member 38, and the front end of the silencing space SP is closed by a front wall 30a of the muffler inlet 30. The silencing space SP is defined by a front first partition wall 44 and a rear second partition wall 46. The lid member 38 is joined by welding to the inner circumferential surface of the rear part of the outer cylinder 34, and the first and second partition walls 44, 46 are joined by welding to the inner circumferential surface of the inner cylinder 32.

[0030] 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. More specifically, the first silencing chamber 41 is formed in the space inside the inner cylinder 32, between the cover member 38 and the second partition wall 46. The second silencing chamber 42 is formed in the space inside the inner cylinder 32 and the muffler inlet 30, by the first partition wall 44 and the front end wall 30a of the muffler inlet 30. The third silencing chamber 43 is formed in the space inside the inner cylinder 32, by the first partition wall 44 and the second partition wall 46.

[0031] Internal pipes 51-53 through which exhaust gas G flows are arranged in the silencing space SP of the exhaust muffler 20. The exhaust muffler 20 of this embodiment includes three internal pipes, namely, first to third internal pipes 51-53.

[0032] The first internal pipe 51 has an upstream end 51a that communicates with the downstream end of the connecting pipe 27. The first internal pipe 51 extends from the upstream end 51a downstream in the flow direction, penetrates the first and second partition walls 44, 46, and has a downstream end 51b that opens into the first silencing chamber 41.

[0033] The first internal pipe 51 is joined by welding to the first and second partition walls 44, 46 at a penetrating portion 51c that penetrates the first and second partition walls 44, 46. In other words, the first internal pipe 51 is supported on the inner diameter surface of the inner cylinder 32 via the first and second partition walls 44, 46. In other words, the portions 44a, 46a of the first and second partition walls 44, 46 that are welded to the inner cylinder 32 of the outer shell member 31 form support portions that support the first internal pipe 51 to the outer shell member 31. The structure of the first internal pipe 51 will be described in detail later.

[0034] The second internal pipe 52 has an upstream end 52a that opens into the first silencing chamber 41. The second internal pipe 52 extends forward from the upstream end 52a, passes through the second partition wall 46 and the first partition wall 44, and has a downstream end 52b that opens into the second silencing chamber 42. The first partition wall 44 is also provided with a through-hole 54 that connects the second silencing chamber 42 and the third silencing chamber 43.

[0035] The third internal pipe 53 has an upstream end 53a that opens into the third silencing chamber 43. The third internal pipe 53 extends rearward from the upstream end 53a, passes through the second partition wall 46, and has a downstream end 53b that opens to the outside of the exhaust muffler 20.

[0036] The exhaust gas G that flows from the connecting pipe 27 into the first internal pipe 51 of the exhaust muffler 20 flows inside the first internal pipe 51 and is led 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 internal pipe 52 and is led 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 internal pipe 53.

[0037] 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. Alternatively, a through-hole that communicates the first silencing chamber 41 and the third silencing chamber 43 may be provided in the second partition wall 46, and exhaust interference (resonance) may occur between the exhaust gas G flowing from the second silencing chamber 42 and the third silencing chamber 43, thereby silencing the exhaust gas G.

[0038] [catalyst] A catalyst 56 is disposed in the first internal pipe 51. The catalyst 56 purifies harmful exhaust components contained in the exhaust gas G. In detail, the first internal pipe 51 has, from the upstream side, a catalyst containing section 58, a straight pipe section 60, and a reduced diameter section 62. The catalyst containing section 58 is the largest diameter section of the first internal pipe 51, and the catalyst 56 is contained therein.

[0039] In this embodiment, the catalyst storage section 58 stores two catalysts 56 lined up in the flow direction of the exhaust gas G. However, the number of catalysts 56 is not limited to two, and may be one, or three or more. Also, in this embodiment, the downstream catalyst 56 has a larger diameter than the upstream catalyst 56. However, the size relationship between the two catalysts 56 is not limited to this, and the upstream catalyst 56 may have a larger diameter, or both may have the same diameter.

[0040] The straight pipe section 60 has a smaller diameter than the catalyst containing section 74 and extends straight in the front-to-rear direction. The reduced diameter section 62 connects the catalyst containing section 58 and the opening 60, and its diameter gradually decreases toward the downstream side. The catalyst containing section 58, straight pipe section 60, and reduced diameter section 62 are configured as separate pipes and are integrated by welding.

[0041] The catalyst containing section 58 has an upstream end 58a joined to the downstream end of the connecting pipe 27, and is in communication with the connecting pipe 27 at the upstream end 58a. In other words, the upstream end 58a of the catalyst containing section 58 constitutes the upstream end 51a of the first internal pipe 51. In addition, the downstream end 58b of the catalyst containing section 58 is joined to the upstream end 62a of the reduced diameter section 62.

[0042] The downstream end 62b of the reduced diameter section 62 is joined to the upstream end 60a of the straight pipe section 60. The downstream end 60b of the straight pipe section 60 opens to the first silencing chamber 41. In other words, the downstream end 60b of the straight pipe section 60 constitutes the downstream end 51b of the first internal pipe 51.

[0043] A straight section of a certain length is required downstream of the catalyst 56, and in this embodiment, this straight section is ensured by the straight pipe section 60. The length of the straight pipe section 60 may be formed to be longer than the diameter of the catalyst 56, for example.

[0044] [Sensor] A downstream sensor 64 is attached to the exhaust muffler 20. The downstream sensor 64 detects the state of the exhaust gas G flowing through the first internal pipe 51. In this embodiment, the downstream sensor 64 is an oxygen sensor that detects the amount of oxygen in the exhaust gas G.

[0045] As shown in Fig. 2, the downstream sensor 64 is covered from the outside by the muffler cover 24. This makes it possible to prevent the downstream sensor 64 from colliding with an obstacle. Covering the downstream sensor 64 with the muffler cover 24 eliminates the need for a dedicated part for covering the downstream sensor 64. Furthermore, although an off-road vehicle such as that of this embodiment is prone to being covered with mud, water, and the like, in this embodiment, the downstream sensor 64 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 (Fig. 3) is disposed upstream of the catalyst 56, and the downstream sensor 64 is disposed downstream of the catalyst 56. The upstream sensor 35 is used, for example, for fuel injection control (air-fuel ratio control). The downstream sensor 64 is used, for example, for fault diagnosis of the catalyst 56.

[0047] The downstream sensor 64 is inserted into the straight pipe portion 60 of the first internal pipe 51. In this embodiment, the portion of the first internal pipe 51 into which the downstream sensor 64 is inserted is the portion of the first internal pipe 51 that is closest to the inner cylinder 32 and the outer cylinder 34, and has a smaller diameter than the catalyst accommodating portion 58. In other words, the downstream sensor 64 is disposed at a position where the passage area is narrowed downstream of the catalyst 56. In this way, by disposing the downstream sensor 64 in an area where the exhaust gas G is concentrated downstream of the catalyst 56, the exhaust gas G that has concentrated in the radial direction can be brought into contact with the sensor, and detection variability can be reduced.

[0048] [Downstream sensor mounting structure] Next, the mounting structure of the downstream sensor 64 will be described with reference to Figure 5. In the following description, the terms "axial direction," "radial direction," and "axial direction" respectively refer to the "axial direction," "radial direction," and "axial direction" of the exhaust muffler 20. The downstream sensor 64 extends radially, penetrating the peripheral walls of the first internal pipe 51, the inner cylinder 32, and the outer cylinder 34.

[0049] An outer shell opening 66 is formed radially through a portion of the peripheral wall of the outer shell member 31. More specifically, an inner cylinder opening 66i is formed radially through a portion of the peripheral wall of the inner cylinder 32, and an outer cylinder opening 66o is formed radially through a portion of the peripheral wall of the outer cylinder 34. In this embodiment, the inner cylinder opening 66i and the outer cylinder opening 66o are formed substantially concentrically, and the outer cylinder opening 66o has a larger diameter than the inner cylinder opening 66i. The inner cylinder opening 66i and the outer cylinder opening 66o form the outer shell opening 66.

[0050] A pipe opening 68 that penetrates radially is formed in a portion of the peripheral wall of the first internal pipe 51. The pipe opening 68 is formed opposite the outer shell opening 66. Here, "the pipe opening 68 is opposite the outer shell opening 66" means that the axis of the pipe opening 68 of the first internal pipe 51 passes through the outer shell opening 66 of the outer shell member 31. In this embodiment, the pipe opening 68 and the outer shell opening 66 are formed to be approximately concentric.

[0051] More specifically, the pipe opening 68 is formed in the straight pipe section 60 of the first internal pipe 51. That is, the straight pipe section 60 constitutes an opening where the pipe opening 68 is formed in the first internal pipe 51. In other words, the pipe opening 68 is formed downstream of the catalyst 56 in the first internal pipe 51.

[0052] In this embodiment, the support portions (penetrating portions) 51c of the first internal pipe 51 are formed on both axial sides of the pipe opening 68. In other words, the first internal pipe 51 is supported by the outer shell member 31 on both axial sides of the pipe opening 68.

[0053] A cylindrical protrusion 69 that protrudes radially is formed on the peripheral wall of the first internal pipe 51. The protrusion 69 is formed around the axis of the pipe opening 68 and protrudes radially outward from the peripheral wall of the first internal pipe 51. In this embodiment, the protrusion 69 is formed separately from the first internal pipe 51 and joined to the outer peripheral surface of the first internal pipe 51 by welding. However, the configuration of the protrusion 69 is not limited to this, and it may be formed integrally with the first internal pipe 51.

[0054] The protruding portion 69 in this embodiment is formed by bending a metal plate. Specifically, the protruding portion 69 has a joint portion 69a joined to the peripheral wall of the first internal pipe 51 and a cylindrical peripheral wall portion 69b extending radially outward from the joint portion 69a. In this embodiment, the protruding portion 69 further has a top wall 69c extending inward from the protruding end of the peripheral wall portion 69b. That is, an internal space S1 is formed in the protruding portion 69 by the peripheral wall portion 69b and the top wall 69c. The internal space S1 is in communication with the pipe opening 68.

[0055] The downstream sensor 64 is disposed so as to block the pipe opening 68. That is, in this embodiment, the oxygen sensor 64 constitutes an internal component that blocks the pipe opening 68. However, the internal component is not limited to the oxygen sensor 64, 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 a component other than a sensor, such as an actuator.

[0056] In this embodiment, the downstream sensor 64 passes through the outer cylinder opening 66o and the inner cylinder opening 66i of the exhaust muffler 20 and is attached to the protruding portion 69. More specifically, a through hole 69d is formed in a top wall 69c of the protruding portion 69, and an attachment portion 70 is provided in the through hole 69d. The downstream sensor 64 is attached to the attachment portion 70.

[0057] In this embodiment, the mounting portion 70 is a cylindrical boss portion having an internal thread 70a formed therein. The outer peripheral surface of the boss portion 70 is joined to the through-hole 69d of the protrusion 69, and the downstream sensor 64 is screwed into the internal thread 70a of the boss portion 70. However, the mounting portion 70 is not limited to a boss portion.

[0058] In this embodiment, the protrusion 69 and the mounting portion 70 are formed separately and joined by welding, but the protrusion 69 and the mounting portion 70 may be formed integrally. Also, in this embodiment, the mounting portion 70 is joined to the through hole 69d of the protrusion 69, but it may be attached to the pipe opening 68 of the first internal pipe 51.

[0059] The sensing portion 64a of the downstream sensor 64 is disposed in the internal space S1 of the protruding portion 69. The sensing portion 64a is a portion that comes into contact with the exhaust gas G flowing through the first internal pipe 51 and acquires the state of the exhaust gas G. However, the sensing portion 64a of the downstream sensor 64 may be disposed inside the first internal pipe 51. In this manner, in this embodiment, the downstream sensor 64 is supported by the protruding portion 69 with the sensing portion 64a disposed in the internal space S1 of the protruding portion 69.

[0060] The outer diameter dimension d1 of the protruding portion 69 is set to be smaller than the inner diameter dimension d2 of the outer shell member 31. Here, the "outer diameter dimension d1 of the protruding portion 69" refers to the dimension from the central line C1 of the muffler to the radially outermost portion of the protruding portion 69. When the protruding portion 69 has an attachment portion 70 as in this embodiment, the "outer diameter dimension d1 of the protruding portion 69" is the dimension of the radially outermost portion of the attachment portion 70.

[0061] Furthermore, "inner diameter dimension d2 of outer shell member 31" refers to the dimension from the central line C1 of the muffler to the radially innermost portion on the inner diameter surface of outer shell member 31. When outer shell member 31 has a double structure consisting of inner cylinder 32 and outer cylinder 34, as in this embodiment, "inner diameter dimension d2 of outer shell member 31" refers to the dimension of the radially innermost portion on the inner diameter surface of inner cylinder 32.

[0062] In this embodiment, the outer diameter dimension d1 of the protrusion 69 is set to be smaller than the outer diameter dimension d3 of the support portions 44a, 46a. Here, the "outer diameter dimension d3 of the support portions 44a, 46a" refers to the dimension from the central line C1 of the muffler to the radially outer portion of the support portions 44a, 46a. When there are multiple support portions 44a, 46a, the "outer diameter dimension d3 of the support portions 44a, 46a" refers to the dimension of the support portion with the smallest diameter. In this embodiment, the outer diameter dimensions d3 of the two support portions 44a, 46a are the same.

[0063] [cap] The exhaust muffler 20 includes a cap 72 that covers the outer shell opening 66 of the outer shell member 31. As shown in Fig. 3, the cap 72 is disposed around the downstream sensor 64 and prevents exhaust gas G from flowing outward from the silencing space SP. The cap 72 of this embodiment is formed by bending a metal plate, and has an elliptical shape with its major axis in the longitudinal direction LD of the exhaust muffler 20 when viewed from the direction of the axis X2 of the downstream sensor 64. In this embodiment, the cap 72 is made of a metal material, but the material and shape are not limited to those of this embodiment as long as it has a structure that closes the opening formed for inserting the sensor.

[0064] The cap 72 has a recess 74 in its center that recesses toward the silencing space SP. More specifically, the cap 72 has an inclined surface 76 that gradually recesses from its outer edge toward its center, and the inclined surface 76 is continuous with the recess 74. The amount of recession of the cap 72 from the outer tube 34 is not constant but varies depending on its circumferential position. In this embodiment, when the cap 72 is attached to a vehicle, the amount of recession of the cap 72 from the outer tube 34 decreases toward the outer side in the vehicle width direction (to the right in this embodiment). This makes it possible to prevent water from accumulating in the recess 74 when the vehicle is upright on the side stand.

[0065] 5, the cap 72 has a pipe-side connection portion 78 connected to the first internal pipe 51 and an outer-cylinder-side connection portion 80 connected to the outer cylinder 34. In this manner, the cap 72 is connected to the radially innermost first internal pipe 51 and the radially outermost outer cylinder 34, but is not connected to the intermediate inner cylinder 32. In this embodiment, the pipe-side connection portion 78 forms the radially inner portion of the cap 72, and the outer-cylinder-side connection portion 80 forms the radially outer inner portion of the cap 72.

[0066] The pipe-side connection portion 78 is joined to a portion of the first internal pipe 51 adjacent to the pipe opening 68. In this embodiment, the pipe-side connection portion 78 is joined to the protruding portion 69 of the first internal pipe 51. In detail, the pipe-side connection portion 78 is joined to the peripheral wall portion 69b of the protruding portion 69 in a state where it overlaps with the peripheral wall portion 69b in the radial direction.

[0067] On the other hand, the outer cylinder side connection portion 80 is joined to the peripheral portion of the outer shell opening 66 of the outer shell member 31. More specifically, the outer cylinder side connection portion 80 is joined to the outer shell member 31 in a state where it overlaps with the outer shell member 31 in the axial direction. In this embodiment, the outer cylinder side connection portion 80 is joined to the peripheral portion of the outer shell opening 66o of the outer cylinder 34. More specifically, the outer cylinder side connection portion 80 is joined to the outer cylinder 34 in a state where it overlaps with the outer shell member 31 in the axial direction.

[0068] The peripheral wall 69b of the protruding portion 69 of the first internal pipe 51 has an outer surface 69ba that is parallel to the axis X2 (FIG. 3) of the downstream sensor 64, i.e., the radial direction of the first internal pipe 51. Meanwhile, the pipe-side connection portion 78 has an inner surface 78a that conforms to the outer surface 69ba of the peripheral wall 69b. The outer surface 69ba of the peripheral wall 69b of the protruding portion 69 and the inner surface 78a of the pipe-side connection portion 78 are joined by welding in a radially overlapping state. At this time, the first internal pipe 51 and the pipe-side connection portion 78 of the cap 72 are relatively movable in directions along the outer surface 69ba and the inner surface 78a, thereby absorbing radial misalignment. In other words, the pipe-side connection portion 78 functions as a radial joint margin during joining.

[0069] The outer tube side connection part 80 is formed by bending the outer end part of the cap 72 in the axial direction and extending it in the axial direction. The outer tube side connection part 80 extends in the axial direction along the outer peripheral surface of the outer tube 34, and the outer tube side connection part 80 and the outer peripheral surface of the outer tube 34 are joined by welding while overlapping in the axial direction. At this time, the outer tube side connection part 80 and the outer tube 34 are movable relative to each other in the axial direction, so that axial misalignment is absorbed. In other words, the outer tube side connection part 80 of the cap 72 functions as an axial joint margin when joined.

[0070] As described above, the cap 72 is welded to the protruding portion 69 of the first internal pipe 51 at the pipe-side connection portion 78. The cap 72 is also welded to the outer cylinder 34 at the outer cylinder-side connection portion 80. The first internal pipe 51 and the outer cylinder 34 are welded all around and sealed via the cap 72, thereby preventing gas from leaking outward from the silencing space SP. The internal cylinder 32 is not welded to the cap 72, and there may be a gap between the internal cylinder 32 and the cap 72. Such a gap absorbs assembly errors.

[0071] The cap 72 is not limited to the structure of this embodiment as long as it is configured to absorb radial and axial misalignment between the outer shell member 31 and the first internal pipe 51 .

[0072] [Regulatory barriers] A restricting wall 82 is provided between the inner cylinder 32 and the outer cylinder 34 near the portion where the downstream sensor 64 is attached. The restricting wall 82 is a member with an L-shaped cross section, and restricts the filler 36 from moving toward the outer shell opening 66. The restricting wall 82 is provided along the downstream sensor 64, i.e., along the outer shell opening 66, and prevents the filler 36 between the inner cylinder 32 and the outer cylinder 34 from shifting toward the outer shell opening 66.

[0073] In this embodiment, an example has been described in which an exhaust muffler 20 is used as the silencer of the present disclosure, but the silencer of the present disclosure is not limited to the exhaust muffler 20, and may be, for example, an exhaust chamber that is arranged upstream of the exhaust muffler 20 and expands the exhaust gas.

[0074] According to the above configuration, by using cap 72 that is separate from outer shell member 31 and first internal pipe 51 shown in FIG. 4 , an assembly error between outer shell member 31 and first internal pipe 51 can be absorbed, preventing exhaust gas G in muffler chamber SP from leaking from outer shell opening 66. Furthermore, the outer diameter dimension d1 of protruding portion 69 of first internal pipe 51 is formed smaller than the inner diameter dimension d2 of outer shell member 31. This prevents protruding portion 69 from getting caught during the process of assembling exhaust muffler 20, and allows first internal pipe 51 with protruding portion 69 to be inserted axially into outer shell member 31. Therefore, the assembly work can be simplified compared to when protruding portion 69 is formed after a pipe main body, before being formed, is inserted into outer shell member 31.

[0075] In this embodiment, a radially outer portion 80 of the cap 72 is joined to the outer shell member 31 while overlapping the first internal pipe 51 in the axial direction, and a radially inner portion 78 of the cap 72 is joined to the protruding portion 69 while overlapping the first internal pipe 51 in the radial direction. With this configuration, the cap 72 can absorb misalignment between the first internal pipe 51 and the outer shell member 31 in both the axial and radial directions.

[0076] In this embodiment, the outer shell member 31 has an inner cylinder 32 in which a silencing chamber SP is formed, and an outer cylinder 34 arranged radially outward of the inner cylinder 32, and a radially outer portion 80 of the cap 72 is joined to the outer cylinder 34 in a state where it overlaps with the axial direction, and the outer diameter dimension d1 of the protruding portion 69 is set to be smaller than the inner diameter dimension d2 of the inner cylinder 32. In this way, the structure of the present disclosure can also be applied to a silencer with a double-cylinder structure.

[0077] In this embodiment, the first internal pipe 51 is supported by the support portions 44a, 46a on the inner diameter surface of the outer shell member 31, and the outer diameter dimension d1 of the protruding portion 69 is set smaller than the outer diameter dimension d3 of the support portions 44a, 46a. With this configuration, the protruding portion 69 is formed to have a smaller diameter than the support portions 44a, 46a, thereby preventing the protruding portion 69 from impeding the support function.

[0078] In the present embodiment, the support portions 44a, 46a are formed on both axial sides of the pipe opening 68. With this configuration, the first internal pipe 51 is supported by the support portions 44a, 46a on both axial ends, thereby increasing the support rigidity in the vicinity of the pipe opening 68 and facilitating the joining operation of the cap 72 to the first internal pipe 51.

[0079] In this embodiment, the protrusion 69 has an attachment portion 70 that supports the internal component 64 inserted into the pipe opening 68. With this configuration, the protrusion 69 has the function of supporting the internal component 64, so there is no need to provide the internal pipe body with a structure to support the internal component, thus simplifying the structure.

[0080] In this embodiment, the diameter of the first internal pipe 51 gradually decreases from a portion located upstream of the pipe opening 68 toward the downstream side. This configuration prevents the portion of the first internal pipe 51 where the protrusion 69 is formed from becoming larger in diameter. As a result, the first internal pipe 51 can be easily inserted into the outer shell member 31.

[0081] In this embodiment, the catalyst 56 is housed in the first internal pipe 51, a pipe opening 68 is formed in the first internal pipe 51 downstream of the catalyst 56, and an oxygen sensor 64 is inserted into the pipe opening 68. With this configuration, the oxygen sensor 64 can detect deterioration of the catalyst 56.

[0082] In this embodiment, the first internal pipe 51 includes a catalyst storage section 58 that stores the catalyst 56, a straight pipe section (opening) 60 in which a pipe opening 68 is formed, and a reduced diameter section 62 that connects the catalyst storage section 58 and the straight pipe section 60 and gradually reduces in diameter toward the downstream side. The catalyst storage section 58, straight pipe section 60, and reduced diameter section 62 are integrated into separate pipes. With this configuration, the catalyst storage section 58 has a large diameter, ensuring a sufficient capacity for the catalyst 56. Furthermore, the straight pipe section 60 has a small diameter, ensuring sufficient space within the silencing chamber SP, thereby improving the flexibility of component placement within the silencing chamber SP. By providing the catalyst storage section 58, straight pipe section 60, and reduced diameter section 62 as separate pipes and integrating them, the first internal pipe 51 can be easily formed into a complex shape.

[0083] In this embodiment, an internal space S1 communicating with the pipe opening 68 is formed inside the protruding portion 69, and the sensing portion 64a of the oxygen sensor 64 is disposed in this internal space S1. This configuration prevents the exhaust gas G from directly colliding with the sensing portion 64a of the oxygen sensor 64, thereby suppressing deterioration of the oxygen sensor 64.

[0084] The structure of the present disclosure is not limited to silencers, but can also be applied to a double-pipe structure having an outer pipe and an inner pipe, thereby achieving both absorption of assembly errors of the double-pipe structure and improvement of assembly ease.

[0085] The vehicle exhaust muffler of the present disclosure includes the following aspects 1 to 11. [Aspect 1] A silencer for silencing engine exhaust gas, an outer shell member having a sound-absorbing chamber formed therein and an outer shell opening formed in a part of a peripheral wall thereof so as to penetrate in a radial direction; an internal pipe disposed in the silencing chamber, the internal pipe radially penetrating a portion of the peripheral wall, the internal pipe having a pipe opening facing the outer shell opening, and the internal pipe having a cylindrical protruding portion that goes around the pipe opening around its axis and protrudes radially relative to the remaining portion; an internal component disposed to close the pipe opening; a cap that is joined to a peripheral portion of the outer shell member around the outer shell opening and to the protruding portion of the internal pipe to cover the outer shell opening, The outer diameter of the protrusion is set smaller than the inner diameter of the outer shell member. [Aspect 2] In the noise suppressor according to aspect 1, a radially outer portion of the cap is joined to the outer shell member in a state where the radially outer portion overlaps the inner pipe in an axial direction, A silencer in which a radially inner portion of the cap is joined to the protrusion in a state where the radially inner portion overlaps the internal pipe. [Aspect 3] In the noise reduction device according to aspect 1 or 2, the outer shell member has an inner cylinder having a noise reduction chamber formed therein and an outer cylinder disposed radially outward of the inner cylinder, a radially outer portion of the cap is joined to the outer cylinder in a state where the radially outer portion overlaps the inner pipe in an axial direction; The outer diameter of the protruding portion is set smaller than the inner diameter of the inner cylinder. [Aspect 4] In the noise reduction device according to any one of Aspects 1 to 3, the internal pipe includes a support portion supported on an inner diameter surface of the outer shell member, The noise suppressor has an outer diameter dimension of the protruding portion set smaller than an outer diameter dimension of the support portion. [Aspect 5] In the noise reduction device according to any one of Aspects 1 to 4, the internal pipe includes a support portion supported by the outer shell member, The support portions are formed on both axial sides of the pipe opening. [Aspect 6] A noise suppressor according to any one of aspects 1 to 5, wherein the protrusion has a mounting portion that supports the internal component. [Aspect 7] A noise suppressor according to any one of aspects 1 to 6, wherein the internal pipe gradually narrows in diameter from a portion away from the pipe opening on the upstream side toward the downstream side. [Aspect 8] 8. The silencer of any one of the first to seventh aspects, wherein the inner pipe contains a catalyst; Furthermore, the internal component includes an oxygen sensor that detects the oxygen concentration of the exhaust gas, The silencer has the pipe opening formed in the internal pipe downstream of the catalyst. [Aspect 9] In the silencer according to aspect 8, the internal pipe has a catalyst storage section in which the catalyst is stored, an opening section in which the pipe opening is formed, and a reduced diameter section that connects the catalyst storage section and the opening section and gradually reduces in diameter downstream, The catalyst storage section, the opening section, and the reduced diameter section are separate pipes that are integrated into the silencer. [Aspect 10] In the silencer according to aspect 8 or 9, the protrusion has an internal space therein that communicates with the pipe opening, The silencer has a sensing portion of the oxygen sensor disposed in the internal space. [Aspect 11] an outer pipe having an outer shell opening formed in a part of a circumferential surface thereof so as to penetrate in a radial direction; an internal pipe disposed in the silencing chamber, the internal pipe having a pipe opening formed therein that radially penetrates a portion of a peripheral surface thereof and faces the outer opening, and the internal pipe having a cylindrical protruding portion that goes around the pipe opening around its axis and protrudes radially relative to the remaining portion; an internal component disposed to close the pipe opening; a cap joined to a peripheral portion of the outer pipe around the outer shell opening and to the protruding portion of the inner pipe to cover the outer shell opening, A double-pipe structure in which the outer diameter of the portion of the inner pipe where the protrusion is formed is set smaller than the inner diameter of the outer shell member.

[0086] The present disclosure is not limited to the above embodiments, and various additions, modifications, or deletions are possible without departing from the spirit and scope of the present disclosure. For example, the vehicle on which the noise reduction device of the present disclosure is installed may be, but is not limited to, a relatively small saddle-ride vehicle in which the driver straddles a seat. For example, the vehicle may be applied to a four-wheel vehicle in which passengers ride side by side in the width direction. The noise reduction device of the present disclosure may also be applied to a hybrid vehicle having an internal combustion engine and an electric motor. The noise reduction device of the present disclosure is preferably applicable to a vehicle in which at least a portion of the outer cylinder of a muffler is exposed to the outside. The noise reduction device of the present disclosure can also be applied to an engine other than the drive source of the vehicle.

[0087] The noise suppressor of the present disclosure can be suitably applied to a double-structure noise suppressor having an inner cylinder and an outer cylinder. In other words, the noise suppressor of the present disclosure can be applied to a triple-structure noise suppressor having a pipe member, an inner cylinder, and an outer cylinder. Therefore, the layout relative to the vehicle is not limited.

[0088] When the silencer of the present disclosure is applied to a motorcycle, the silencer may be disposed on one of the outer sides of the rear wheel in the vehicle width direction, or on both outer sides of the rear wheel in the vehicle width direction. The silencer may also be disposed directly above the rear wheel, or may be disposed between the rear wheel and the engine as an exhaust chamber. Regarding the structure partitioned within the silencer chamber, the above embodiment is merely an example, and any other existing structure may be used as long as it has at least a double structure of an outer shell member and a pipe member. Therefore, such structures are also included within the scope of the present disclosure. [Explanation of symbols]

[0089] 20 Exhaust muffler (silencer) 31 Outer shell member (outer pipe) 32 Inner cylinder 34 outer cylinder 44a,46a Support part 51 First internal pipe (internal pipe) 56 Catalyst 58 Catalyst storage section 60 Straight pipe section (opening) 62 Reduced diameter part 64 Downstream sensor (oxygen sensor (internal part)) 64a Sensing section 66 Shell Opening 68 Pipe Opening 69 Protrusion 70 Boss part (mounting part) 72 Cap d1 Outer diameter of protrusion d2 Inner diameter of outer shell d3 Outer diameter of support part E-Engine S1 Internal space (inside the protrusion)

Claims

1. A silencer for silencing engine exhaust gas, an outer shell member having a sound-absorbing chamber formed therein and an outer shell opening formed in a part of a peripheral wall thereof so as to penetrate in a radial direction; an internal pipe disposed in the silencing chamber, the internal pipe radially penetrating a portion of the peripheral wall, the internal pipe having a pipe opening facing the outer shell opening, and the internal pipe having a cylindrical protruding portion that goes around the pipe opening around its axis and protrudes radially relative to the remaining portion; an internal component disposed to close the pipe opening; a cap that is joined to a peripheral portion of the outer shell member around the outer shell opening and to the protruding portion of the internal pipe to cover the outer shell opening, The outer diameter of the protrusion is set smaller than the inner diameter of the outer shell member.

2. 2. The silencer according to claim 1, wherein a radially outer portion of the cap is joined to the outer shell member in a state where the radially outer portion overlaps the inner pipe in an axial direction, A silencer in which a radially inner portion of the cap is joined to the protrusion in a state where the radially inner portion overlaps the internal pipe.

3. 3. The noise suppressor according to claim 1, wherein the outer shell member has an inner cylinder having a noise suppression chamber formed therein, and an outer cylinder disposed radially outward of the inner cylinder, a radially outer portion of the cap is joined to the outer cylinder in a state where the radially outer portion overlaps the inner pipe in an axial direction; The outer diameter of the protruding portion is set smaller than the inner diameter of the inner cylinder.

4. 3. The silencer according to claim 1, wherein the internal pipe includes a support portion supported on an inner diameter surface of the outer shell member, The noise suppressor has an outer diameter dimension of the protruding portion set smaller than an outer diameter dimension of the support portion.

5. 3. The silencer according to claim 1, wherein the internal pipe includes a support portion supported by the outer shell member, The support portions are formed on both axial sides of the pipe opening.

6. 3. A silencer according to claim 1, wherein said protrusion has a mounting portion for supporting said internal component.

7. 3. The silencer according to claim 1, wherein the internal pipe has a diameter that gradually decreases from a portion located upstream of the pipe opening toward the downstream side.

8. 3. The silencer according to claim 1, wherein a catalyst is accommodated in the internal pipe, Furthermore, the internal component includes an oxygen sensor that detects the oxygen concentration of the exhaust gas, The silencer has the pipe opening formed in the internal pipe downstream of the catalyst.

9. 9. The silencer according to claim 8, wherein the internal pipe has a catalyst storage section in which the catalyst is stored, an opening section in which the pipe opening is formed, and a reduced diameter section that connects the catalyst storage section and the opening section and gradually reduces in diameter downstream, The catalyst storage section, the opening section, and the reduced diameter section are separate pipes that are integrated into the silencer.

10. 9. The silencer according to claim 8, wherein the protrusion has an internal space therein that communicates with the pipe opening, The silencer has a sensing portion of the oxygen sensor disposed in the internal space.

11. an outer pipe having an outer shell opening formed in a part of a circumferential surface thereof so as to penetrate in a radial direction; an internal pipe disposed in the silencing chamber, the internal pipe having a pipe opening formed therein that radially penetrates a portion of a peripheral surface thereof and faces the outer opening, and the internal pipe having a cylindrical protruding portion that goes around the pipe opening around its axis and protrudes radially relative to the remaining portion; an internal component disposed to close the pipe opening; a cap joined to a peripheral portion of the outer pipe around the outer shell opening and to the protruding portion of the inner pipe to cover the outer shell opening, A double-pipe structure in which the outer diameter of the portion of the inner pipe where the protrusion is formed is set smaller than the inner diameter of the outer shell member.

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