Exhaust device

Abstract

To install an exhaust gas sensor in the vicinity of a connection part while reinforcing the connection part of a muffler body and an exhaust pipe.SOLUTION: An exhaust device (30) guides exhaust gas discharged from an engine to the outside. The exhaust device includes: a catalyst case (32) installed downstream of the engine; a muffler body (52) installed downstream of the catalyst case; a first exhaust pipe (35) extending from the catalyst case to the downstream side; a second exhaust pipe (41) in which an upstream end part (42) projects from the muffler body; and an exhaust gas sensor installed on an outer peripheral surface of the first exhaust pipe. A downstream end part (36) of the first exhaust pipe enters into an inner side of the upstream end part of the second exhaust pipe, and an inclined end surface (43) slantly cut is formed in the upstream end part of the second exhaust pipe. At least part of the exhaust gas sensor is located downstream of a tip of the inclined end surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an exhaust system. [Background technology]

[0002] Conventionally, an exhaust system for a saddle-ride type vehicle has been known in which a catalyst case is installed near the engine (see, for example, Patent Document 1). In the exhaust system described in Patent Document 1, an exhaust pipe extends rearward from the cylinder head of the engine and is connected to the catalyst case below the engine. Furthermore, an exhaust pipe extends rearward from the catalyst case and is connected to a muffler body behind the engine. Exhaust gas flows from the engine through the exhaust pipe into the catalyst case, where it is purified, and exhaust noise is reduced by flowing from the catalyst case into the muffler body through the exhaust pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6571874 Summary of the Invention [Problem to be solved by the invention]

[0004] However, vibrations of the vehicle body and muffler body place a heavy load on the connection between the muffler body and the exhaust pipe. In particular, in the exhaust system of Patent Document 1, vibrations increase due to the catalyst, which is a heavy object, being installed inside the catalyst case. An exhaust gas sensor must be installed downstream of the catalyst case to diagnose catalyst deterioration, but depending on the vehicle layout, the installation location of the exhaust gas sensor is limited to near the connection between the muffler body and the exhaust pipe. For this reason, installing a reinforcing member or the like at the connection makes it impossible to install the exhaust gas sensor.

[0005] The present invention has been made in consideration of these points, and aims to provide an exhaust device that can reinforce the connection between the muffler body and the exhaust pipe while allowing an exhaust gas sensor to be installed near the connection. [Means for solving the problem]

[0006] An exhaust device of one embodiment of the present invention is an exhaust device that directs exhaust gas emitted from an engine to the outside, and comprises a catalyst case installed downstream of the engine, a muffler body installed downstream of the catalyst case, a first exhaust pipe extending downstream from the catalyst case, a second exhaust pipe whose upstream end protrudes from the muffler body, and an exhaust gas sensor installed on the outer surface of the first exhaust pipe, wherein the downstream end of the first exhaust pipe extends inside the upstream end of the second exhaust pipe, the upstream end of the second exhaust pipe forms an inclined end face that is cut at an angle, and at least a portion of the exhaust gas sensor is located downstream of the tip of the inclined end face, thereby solving the above-mentioned problem. [Effects of the Invention]

[0007] According to one aspect of the exhaust device of the present invention, the double-pipe structure of the first and second exhaust pipes is ensured to be long only in the truncated portion of the upstream end of the second exhaust pipe, thereby increasing the strength of the joint between the muffler body and the second exhaust pipe. Furthermore, by joining the inclined end face of the second exhaust pipe to the outer peripheral surface of the first exhaust pipe, a long joint length is ensured, thereby increasing the strength of the joint between the first and second exhaust pipes. Furthermore, by cutting the second exhaust pipe at an angle, space for installing an exhaust gas sensor is ensured on the outer peripheral surface of the first exhaust pipe. Therefore, the joint between the muffler body and the second exhaust pipe can be reinforced while the exhaust gas sensor can be installed near the joint. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a right side view of the saddle-ride type vehicle of the present embodiment. [Figure 2] FIG. 2 is a right side view of the exhaust device of the present embodiment. [Figure 3] FIG. 2 is a left side view of the exhaust device of the present embodiment. [Figure 4] FIG. 2 is a bottom view of the periphery of the muffler body of the present embodiment. [Figure 5] FIG. 2 is a right side view of the periphery of the muffler body of the present embodiment. [Figure 6] FIG. 2 is a rear view of the muffler body and its periphery according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An exhaust system according to one embodiment of the present invention guides exhaust gas emitted from an engine to the outside. The exhaust system includes a catalyst case disposed downstream of the engine and a muffler body disposed downstream of the catalyst case. A first exhaust pipe extends downstream from the catalyst case, and the upstream end of a second exhaust pipe protrudes from the muffler body. The downstream end of the first exhaust pipe is inserted into the upstream end of the second exhaust pipe, and the upstream end of the second exhaust pipe is formed with an obliquely cut inclined end face. An exhaust gas sensor is disposed on the outer peripheral surface of the first exhaust pipe, and at least a portion of the exhaust gas sensor is located downstream of the tip of the inclined end face. The double-pipe structure of the first and second exhaust pipes is ensured to be long only in the truncated portion of the upstream end of the second exhaust pipe, thereby increasing the strength of the joint between the muffler body and the second exhaust pipe. Furthermore, the inclined end face of the second exhaust pipe is joined to the outer peripheral surface of the first exhaust pipe, thereby ensuring a long joint length and increasing the strength of the joint between the first and second exhaust pipes. Furthermore, by cutting the second exhaust pipe at an angle, space is secured on the outer surface of the first exhaust pipe for installing an exhaust gas sensor, which allows the exhaust gas sensor to be installed near the connection between the muffler body and the second exhaust pipe while reinforcing the connection. [Example]

[0010] A saddle-riding type vehicle equipped with an exhaust system of this embodiment will be described below with reference to the accompanying drawings. Fig. 1 is a right side view of the saddle-riding type vehicle of this embodiment. In the following drawings, arrow Fr indicates the front of the vehicle, arrow Re indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle.

[0011] As shown in Fig. 1, a saddle-type vehicle 1 is configured by attaching various covers to an underbone-type body frame as the exterior of the vehicle. A front cover 11 is provided at the front of the vehicle, and a front leg shield 12 that protects the rider's legs is provided behind the front cover 11. A floor board 13 extends rearward from the lower end of the front leg shield 12, and a body cover 14 and a pair of side covers 15 are provided behind the floor board 13. A seat 16 consisting of a series of seating surfaces for the driver and passenger is provided above the side cover 15.

[0012] Handlebars 21 are provided above front cover 11, and a front wheel 23 is rotatably supported below front cover 11 via a pair of front forks 22. A unit swing-type engine 24 is provided below side cover 15. The engine 24 is swingably connected to the body frame, and a rear wheel 27 is rotatably supported at the rear of engine 24. Exhaust pipes 35, 41 extend from engine 24 toward the rear of the vehicle, and a muffler 51 is connected downstream of exhaust pipes 35, 41. Muffler 51 is supported on the right side of engine 24 via a support bracket 53.

[0013] However, in recent years, stricter exhaust gas regulations have made it necessary to install larger catalysts in the exhaust pipe. In order for the catalyst to demonstrate its purification performance immediately after starting, high-temperature exhaust gas must be passed through the catalyst, which requires that the catalyst be installed near the engine's exhaust port. Furthermore, in order to comply with stricter noise regulations, mufflers have become larger and more complex in structure, resulting in increased muffler weight. The catalyst and muffler increase the weight of the upstream and downstream sides of the exhaust pipe, which increases the vibration of the exhaust system and makes it more likely that a heavy load will be placed on the connection between the muffler body and the exhaust pipe.

[0014] In this case, it is possible to support the catalyst case with the engine upstream of the exhaust pipe, but adding brackets and other components would increase the number of parts and the assembly work. Another possible configuration is to interpose the catalyst case between the exhaust pipe and the muffler downstream of the exhaust pipe, using the catalyst case and catalyst as reinforcing members, but this would result in the catalyst being separated from the engine's exhaust port, reducing purification performance immediately after starting. Furthermore, an exhaust gas sensor for diagnosing catalyst deterioration must be installed in the exhaust pipe, but depending on the vehicle layout, the location where the exhaust gas sensor can be installed is limited to near the muffler.

[0015] Therefore, in this embodiment, the exhaust pipe is made into a double-pipe structure near the muffler, and the connection between the muffler body and the exhaust pipe is reinforced. In order to install an exhaust gas sensor near the muffler, a through-hole for the sensor must be formed in the outer and inner tubes of the exhaust pipe, but it is difficult to accurately align the through-holes of the outer and inner tubes of the exhaust pipe and join the tubes together. For this reason, a through-hole is formed only in the inner tube of the exhaust pipe, and the outer tube of the exhaust pipe is cut diagonally so that this through-hole is exposed to the outside, thereby ensuring a long reinforced area of ​​the double-pipe structure while also ensuring a location for installing the exhaust gas sensor near the muffler.

[0016] The exhaust device of this embodiment will be described with reference to Figures 2 and 3. Figure 2 is a right side view of the exhaust device of this embodiment, and Figure 3 is a left side view of the exhaust device of this embodiment.

[0017] As shown in Figures 2 and 3, the exhaust system 30 is formed by connecting an expanded diameter pipe 31, a catalyst case 32, a reduced diameter pipe 34, a first exhaust pipe 35, a second exhaust pipe 41, a muffler 51, and a tail pipe 55. These components form an exhaust passage extending from the engine 24 (see Figure 1) to the rear of the vehicle. The expanded diameter pipe 31 extends downward from the exhaust port of the engine 24 and then curves to the right. The expanded diameter pipe 31 expands in diameter toward the downstream side, and a mounting boss 37 for an exhaust gas sensor (not shown) is provided at the small diameter portion of the expanded diameter pipe 31. The expanded diameter pipe 31 has a bun-shaped structure consisting of front and rear pipe halves.

[0018] The catalyst case 32 and the reduced diameter pipe 34 are formed as a single unit. The catalyst case 32 extends rightward from the downstream end of the expanded diameter pipe 31, and the reduced diameter pipe 34 curves rearward from the downstream end of the catalyst case 32. The catalyst case 32 is located directly below the cylinder head, and a large catalyst 33 is housed inside the catalyst case 32. Air pollutants such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen compounds (NOx) in the exhaust gas are purified as the exhaust gas passes through the catalyst 33. The catalyst case 32 and the reduced diameter pipe 34 are formed in a sandwich structure consisting of upper and lower pipe halves.

[0019] The first exhaust pipe 35 extends rearward from the downstream end of the reduced-diameter pipe 34, passing to the right of the engine 24. A mounting boss 45 for an exhaust gas sensor 48 (see FIG. 4) is provided downstream of the first exhaust pipe 35. The mounting boss 45 protrudes inward in the vehicle width direction from the outer surface of the first exhaust pipe 35. An exhaust gas sensor 48 is installed in each of the mounting bosses 37, 45, and the exhaust gas sensor 48 detects the oxygen concentration in the exhaust gas. The detection result of the exhaust gas sensor upstream of the catalyst 33 is used for feedback control of the fuel injection amount, and the detection result of the exhaust gas sensor 48 downstream of the catalyst 33 is used for diagnosing deterioration of the catalyst 33.

[0020] The second exhaust pipe 41 fits inside the muffler body 52 of the muffler 51, and the truncated cylindrical upstream end 42 of the second exhaust pipe 41 protrudes forward from the muffler body 52. ​​The downstream end 36 of the first exhaust pipe 35 is inserted into the upstream end 42 of this second exhaust pipe 41, and the first and second exhaust pipes 35, 41 form a double-pipe exhaust pipe structure near the muffler 51. The upstream end 42 of the second exhaust pipe 41 is formed with an obliquely cut inclined end face 43, and this inclined end face 43 of the second exhaust pipe 41 is joined to the outer peripheral surface of the first exhaust pipe 35 by welding. A tip 44 of the inclined end face 43 is positioned outward in the vehicle width direction so as not to interfere with the mounting boss 45.

[0021] The muffler body 52 of the muffler 51 is formed into a cylindrical shape by left and right case halves. A front opening is formed in the muffler body 52, and the outer peripheral surface of the second exhaust pipe 41 is welded to the edge of the opening of the muffler body 52. ​​A silencing chamber is formed inside the muffler body 52, and exhaust gas flows from the second exhaust pipe 41 into the silencing chamber, causing the exhaust gas to expand and reducing exhaust noise. A rear opening is formed in the muffler body 52, and a tail pipe 55 protrudes rearward from the rear opening of the muffler body 52. ​​Exhaust gas in the silencing chamber is discharged to the outside through the tail pipe 55.

[0022] In this way, exhaust gas emitted from the engine 24 is guided to the outside by the exhaust system 30. A catalyst case 32 is installed downstream of the engine 24, and a muffler body 52 is installed downstream of the catalyst case 32. A first exhaust pipe 35 extends downstream from the catalyst case 32, and an upstream end 42 of a second exhaust pipe 41 protrudes from the muffler body 52, with the downstream end 36 of the first exhaust pipe 35 inserted inside the upstream end 42 of the second exhaust pipe 41, forming a double-pipe structure. The first and second exhaust pipes 35, 41 are joined near the muffler 51, and a downstream exhaust gas sensor 48 is installed near the joint.

[0023] A support bracket 53 is attached to the front of the muffler body 52. ​​A pair of upper and lower arms 54 extend forward from the support bracket 53, and the tip ends of the pair of arms 54 are screwed to the engine case 25 (see Figure 5) to attach the muffler body 52 to the vehicle body. The engine case 25 protrudes downward in front of the muffler body 52, so the exhaust gas sensor 48 cannot be installed where the first exhaust pipe 35 and the engine case 25 overlap in side view. For this reason, the installation location of the downstream exhaust gas sensor 48 is limited to near the muffler body 52.

[0024] The detailed configuration of the exhaust device will be described with reference to Figures 4 to 6. Figure 4 is a bottom view of the periphery of the muffler body of this embodiment. Figure 5 is a right side view of the periphery of the muffler body of this embodiment. Figure 6 is a rear view of the periphery of the muffler body of this embodiment.

[0025] As shown in Figure 4, the upstream end 42 of the second exhaust pipe 41 protrudes forward from the front opening of the muffler body 52, and the downstream end 36 of the first exhaust pipe 35 is inserted into the upstream end 42 of the second exhaust pipe 41. The upstream end 42 of the second exhaust pipe 41 extends to near the rear of the engine case 25, and an obliquely cut inclined end face 43 is formed at the upstream end 42. The inclined end face 43 is inclined so that it is positioned outward in the vehicle width direction as it approaches the upstream side. The outer peripheral surface of the first exhaust pipe 35 is exposed upstream of the inclined end face 43, and an exhaust gas sensor 48 is installed on the outer peripheral surface of the first exhaust pipe 35 so as not to interfere with the inclined end face 43.

[0026] In this case, at least a portion of the exhaust gas sensor 48 is located downstream of the tip 44 of the inclined end face 43. This portion is reinforced by the first and second exhaust pipes 35, 41 in a double-pipe structure, but by cutting the second exhaust pipe 41 at an angle, space for installing the exhaust gas sensor 48 is secured on the outer peripheral surface of the first exhaust pipe 35. In addition, the inclined end face 43 is formed in an elliptical shape, and the inclined end face 43 of the second exhaust pipe 41 is joined by welding to the outer peripheral surface of the first exhaust pipe 35 outside the muffler body 52. ​​A long weld length is secured between the first and second exhaust pipes 35, 41, increasing the strength of the joint between the first and second exhaust pipes 35, 41.

[0027] The downstream end 36 of the first exhaust pipe 35 extends into the inside of the muffler body 52, and the double-pipe structure of the first and second exhaust pipes 35, 41 is longer and stronger. Increasing the rigidity of the first and second exhaust pipes 35, 41 reduces the load acting on the joint between the first and second exhaust pipes 35, 41, as well as the load acting on the connection 57 between the muffler body 52 and the second exhaust pipe 41. In this way, the double-pipe structure of the first and second exhaust pipes 35, 41 reinforces the connection 57 between the muffler body 52 and the second exhaust pipe 41, and by cutting the second exhaust pipe 41 at an angle, the exhaust gas sensor 48 can be installed near the connection 57.

[0028] The tip 44 of the inclined end surface 43 is located on the outer side of the first exhaust pipe 35 in the vehicle width direction. As the inclined end surface 43 faces inward in the vehicle width direction, the joint between the first and second exhaust pipes 35, 41 is less noticeable, improving the appearance of the vehicle body. The exhaust gas sensor 48 is located on the opposite side of the first exhaust pipe 35 from the tip 44 of the inclined end surface 43. As the exhaust gas sensor 48 is located on the inner side of the first exhaust pipe 35 in the vehicle width direction, the exhaust gas sensor 48 is covered by the first and second exhaust pipes 35, 41 from the outer side in the vehicle width direction, and the exhaust gas sensor 48 is protected by the first and second exhaust pipes 35, 41. Furthermore, as the exhaust gas sensor 48 is installed in a location with high rigidity, damage to the exhaust gas sensor 48 due to vibration is reduced.

[0029] A support bracket 53 is provided on the muffler body 52, and extends forward from the muffler body 52. ​​The rear half of the support bracket 53 is joined to the muffler body 52, and the front half of the support bracket 53 is divided into upper and lower parts and forms a pair of arm portions 54 that extend forward (see FIG. 2 in particular). The tips of the pair of arm portions 54 are fixed to the engine case (vehicle body) 25 with a pair of bolts, and the muffler body 52 is supported on the engine case 25 via the support bracket 53. The first and second exhaust pipes 35, 41 pass outside the support bracket 53 in the vehicle width direction.

[0030] In this case, a fixed position P1 of the support bracket 53 relative to the engine 24 is offset outward in the vehicle width direction with respect to a center of gravity P2 of the muffler body 52. ​​The muffler body 52 is likely to move outward in the vehicle width direction with the fixed position P1 as a fulcrum, but the weld lengths of the first and second exhaust pipes 35, 41 are ensured to be long, thereby increasing the strength of the joint between the first and second exhaust pipes 35, 41. Furthermore, the tip 44 of the inclined end face 43 of the first exhaust pipe 35 is positioned on the side of the center of gravity P2 of the muffler body 52. ​​A compressive load is generated at the joint between the first and second exhaust pipes 35, 41 due to a force acting inward in the vehicle width direction, and a tensile load is generated at the joint between the first and second exhaust pipes 35, 41 due to a force acting outward in the vehicle width direction.

[0031] When the muffler body 52 moves outward in the vehicle width direction, a force acts on the tip 44 of the inclined end face 43 in the inward direction of the vehicle width, causing a compressive load at the joint between the first and second exhaust pipes 35, 41. When the muffler body 52 moves inward in the vehicle width direction, a force acts on the tip 44 of the inclined end face 43 in the outward direction of the vehicle width, causing a tensile load at the joint between the first and second exhaust pipes 35, 41. The muffler body 52 tends to move outward in the vehicle width direction, so the compressive load is greater than the tensile load at the joint between the first and second exhaust pipes 35, 41. Generally, the compressive strength is greater than the tensile strength at the joint, so damage to the joint between the first and second exhaust pipes 35, 41 can be reduced.

[0032] As shown in Figures 5 and 6, the inclined end surface 43 and the exhaust gas sensor 48 are located below the support bracket 53. The support bracket 53 covers the joint between the first and second exhaust pipes 35, 41 and the exhaust gas sensor 48 from above, protecting the joint between the first and second exhaust pipes 35, 41 and the exhaust gas sensor 48. The rider cannot touch the exhaust gas sensor 48 regardless of their riding position. In addition, a main stand 28 is attached to the engine case 25, and the exhaust gas sensor 48 is located above the main stand 28. The main stand 28 covers the exhaust gas sensor 48 from below, protecting the exhaust gas sensor 48.

[0033] The oil filler cap 26 of the engine 24 is positioned between a pair of arms 54 of the support bracket 53. The exhaust gas sensor 48 is positioned below the oil filler cap 26, and the lead wires 49 of the exhaust gas sensor 48 run further inward in the vehicle width direction than the oil filler cap 26 and the support bracket 53. Even if the oil filler cap 26 is brought close to the muffler body 52, the exhaust gas sensor 48 and lead wires 49 do not get in the way of cap operation. This improves the efficiency of the engine oil refueling operation and prevents damage to the lead wires 49.

[0034] As described above, according to the exhaust system 30 of this embodiment, the double-pipe structure of the first and second exhaust pipes 35, 41 is ensured to be long only in the truncated portion of the upstream end 42 of the second exhaust pipe 41, thereby increasing the strength of the connection portion 57 between the muffler body 52 and the second exhaust pipe 41. Furthermore, by joining the inclined end face 43 of the second exhaust pipe 41 to the outer peripheral surface of the first exhaust pipe 35, a long connection length is ensured, thereby increasing the strength of the connection portion between the first and second exhaust pipes 35, 41. Furthermore, by cutting the second exhaust pipe 41 at an angle, space for installing the exhaust gas sensor 48 is ensured on the outer peripheral surface of the first exhaust pipe 35. Therefore, the connection portion 57 between the muffler body 52 and the second exhaust pipe 41 is reinforced, and the exhaust gas sensor 48 can be installed near the connection portion 57.

[0035] In this embodiment, a single-cylinder engine is exemplified, but the type of engine is not particularly limited, and may be, for example, a multi-cylinder engine having two or more cylinders. Also, although a unit swing type engine is exemplified, the engine is not limited to the unit swing type.

[0036] In addition, in this embodiment, an oxygen sensor that detects oxygen concentration is used as an example of the exhaust gas sensor, but the exhaust gas sensor may be any sensor that can detect the average characteristics of the exhaust gas, and may be, for example, an exhaust temperature sensor that detects the exhaust temperature of the exhaust gas.

[0037] Furthermore, in this embodiment, exhaust gas sensors are installed on both the upstream and downstream sides of the catalyst, but it is sufficient to install at least one exhaust gas sensor on the downstream side of the catalyst.

[0038] Furthermore, in this embodiment, the muffler body is supported on the engine case via a support bracket, but the muffler body may also be supported on the vehicle frame via a support bracket.

[0039] In addition, in this embodiment, the inclined end face is directed inward in the vehicle width direction, and the exhaust gas sensor is installed on the inside of the first exhaust pipe in the vehicle width direction, but the inclined end face may also be directed outward in the vehicle width direction, and the exhaust gas sensor may be installed on the outside of the first exhaust pipe in the vehicle width direction.

[0040] Furthermore, the exhaust system of this embodiment is not limited to the saddle-ride type vehicle described above, and may be used in other types of saddle-ride type vehicles. Note that a saddle-ride type vehicle is not limited to all vehicles in which the rider sits astride the seat, but also includes scooter-type vehicles in which the rider does not sit astride the seat.

[0041] As described above, the first aspect is an exhaust system (30) that guides exhaust gas emitted from an engine (24) to the outside, and includes a catalyst case (32) located downstream of the engine, a muffler body (52) located downstream of the catalyst case, a first exhaust pipe (35) extending downstream from the catalyst case, a second exhaust pipe (41) whose upstream end (42) protrudes from the muffler body, and an exhaust gas sensor (48) located on the outer circumferential surface of the first exhaust pipe, wherein the downstream end (36) of the first exhaust pipe fits inside the upstream end of the second exhaust pipe, and the upstream end of the second exhaust pipe is formed with an obliquely cut inclined end face (43), and at least a portion of the exhaust gas sensor is located downstream of the tip (44) of the inclined end face. With this configuration, the double-pipe structure of the first and second exhaust pipes is ensured to be long only at the truncated portion of the upstream end of the second exhaust pipe, thereby increasing the strength of the connection between the muffler body and the second exhaust pipe. Furthermore, by joining the inclined end face of the second exhaust pipe to the outer peripheral surface of the first exhaust pipe, a long joint length is ensured, increasing the strength of the joint between the first and second exhaust pipes. Furthermore, by cutting the second exhaust pipe at an angle, space is ensured on the outer peripheral surface of the first exhaust pipe to install an exhaust gas sensor. This allows the exhaust gas sensor to be installed near the joint while reinforcing the connection between the muffler body and the second exhaust pipe.

[0042] In the second aspect, in the first aspect, the inclined end face faces inward in the vehicle width direction, and the exhaust gas sensor is installed on the inside of the first exhaust pipe in the vehicle width direction. With this configuration, the joint between the first and second exhaust pipes becomes less noticeable, improving the appearance of the vehicle body. The exhaust gas sensor is covered by the first and second exhaust pipes from the outside in the vehicle width direction, and is protected by the first and second exhaust pipes.

[0043] In the third aspect, in the first or second aspect, the downstream end of the first exhaust pipe extends into the inside of the muffler body. With this configuration, the double pipe structure of the first and second exhaust pipes can be lengthened and strengthened.

[0044] A fourth aspect is any one of the first to third aspects, further comprising a support bracket (53) for attaching the muffler body to the vehicle body, and the fixed position (P1) of the support bracket relative to the vehicle body is offset in the vehicle width direction from the center of gravity position (P2) of the muffler body, with the tip of the inclined end face of the first exhaust pipe positioned toward the center of gravity of the muffler body. With this configuration, the muffler body is more likely to move toward the offset side, and a strong load is generated in the compression direction at the tip of the second exhaust pipe. This can increase the strength of the joint between the first and second exhaust pipes compared to when a strong load is generated in the tension direction at the tip of the second exhaust pipe.

[0045] A fifth aspect is any one of the first to fourth aspects, and further includes a support bracket for attaching the muffler body to the vehicle body, the support bracket extending forward from the muffler body, and the inclined end surface and the exhaust gas sensor positioned below the support bracket. With this configuration, the support bracket covers the joint between the first and second exhaust pipes and the exhaust gas sensor from above, protecting the joint between the first and second exhaust pipes and the exhaust gas sensor. It is also possible to prevent the driver from touching the joint or the exhaust gas sensor.

[0046] In a sixth aspect, in the fourth or fifth aspect, the support bracket has a pair of arms (54) that extend forward from the muffler body, with the engine oil filler cap (26) positioned between the pair of arms and the exhaust gas sensor positioned below the oil filler cap, with the exhaust gas sensor lead wires (49) passing inward in the vehicle width direction from the oil filler cap. With this configuration, even if the oil filler cap is brought close to the muffler body, the exhaust gas sensor and lead wires do not get in the way of cap operation. This improves the efficiency of engine oil filling work and prevents damage to the lead wires.

[0047] Although the present embodiment has been described, other embodiments may be made by combining the above-described embodiments and modifications in whole or in part.

[0048] Furthermore, the technology of the present invention is not limited to the above-described embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea. Furthermore, if the technical idea can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of symbols]

[0049] 24: Engine 25: Engine case (body) 26: Oil filler cap 30: Exhaust system 32: Catalyst case 33: Catalyst 35: First exhaust pipe 36: Downstream end 41: Second exhaust pipe 42: Upstream end 43: Inclined end face 44: Tip 48: Exhaust gas sensor 49: Lead wire 51: Muffler 52: Muffler body 53: Support bracket 54: Arm section 57: Connection

Claims

1. An exhaust device that guides exhaust gas emitted from an engine to the outside, a catalyst case disposed downstream of the engine; a muffler body disposed downstream of the catalyst case; a first exhaust pipe extending downstream from the catalyst case; a second exhaust pipe having an upstream end protruding from the muffler body; an exhaust gas sensor installed on an outer peripheral surface of the first exhaust pipe, a downstream end of the first exhaust pipe is inserted into an inside of an upstream end of the second exhaust pipe, and an inclined end face is formed at the upstream end of the second exhaust pipe by being cut obliquely; An exhaust system characterized in that at least a portion of the exhaust gas sensor is located downstream of the tip of the inclined end surface.

2. 2. The exhaust system according to claim 1, wherein the inclined end surface faces inward in the vehicle width direction, and the exhaust gas sensor is installed on the inner side of the first exhaust pipe in the vehicle width direction.

3. 3. The exhaust system according to claim 1, wherein a downstream end of the first exhaust pipe extends into the inside of the muffler body.

4. a support bracket for attaching the muffler body to a vehicle body; 3. The exhaust device according to claim 1, wherein a fixed position of the support bracket relative to the vehicle body is offset in the vehicle width direction from a center of gravity of the muffler body, and a tip of the inclined end face of the first exhaust pipe is positioned toward the center of gravity of the muffler body.

5. a support bracket for attaching the muffler body to a vehicle body; The support bracket extends forward from the muffler body, 3. The exhaust system according to claim 1, wherein the inclined end surface and the exhaust gas sensor are located below the support bracket.

6. The support bracket has a pair of arms that extend forward from the muffler body, one above the other, an oil filler cap of the engine is positioned between the pair of arms, and the exhaust gas sensor is positioned below the oil filler cap; 5. The exhaust system according to claim 4, wherein the lead wires of the exhaust gas sensor are routed inward in the vehicle width direction relative to the oil filler cap.

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