EXHAUST DEVICE FOR INTERNAL COMBUSTION ENGINE

Abstract

An exhaust device 39 for an internal combustion engine 10 mounted in a saddle-type vehicle 10 according to one embodiment of the present invention comprises: an exhaust purification catalyst 48a provided in an exhaust passage 52 of an internal combustion engine E; and an exhaust gas sensor 46 provided in a downstream exhaust passage 52b downstream of the exhaust purification catalyst 48a. The exhaust gas sensor 46 is provided in a connecting part 70 welded to an exhaust pipe 50 that compartmentally forms the downstream exhaust passage 52b, inclined at an angle to the exhaust flow direction EF. A weld start portion B1 of a weld 70 around the connecting part 70W with respect to the exhaust pipe 50 is located non-upstream of the exhaust gas sensor 46 in the exhaust flow direction EF.

Description

1 / 30 EXHAUST DEVICE FOR INTERNAL COMBUSTION ENGINE Technical field

[001] The present invention relates to an exhaust device for an internal combustion engine mounted on a ride-on type vehicle such as a motorcycle. prior technique

[002] Efforts to mitigate climate change or reduce its impact have been continuously and conventionally undertaken, and research and development on emissions improvement has been conducted with this aim. For example, in internal combustion engines for vehicles, including ride-on vehicles such as motorcycles, several studies have been conducted on providing an exhaust gas sensor in an exhaust passage of an internal combustion engine and controlling fuel injection according to an output from the exhaust gas sensor to purify the exhaust gas.

[003] For example, Patent Document 1 discloses that a fastening portion into which an oxygen concentration sensor is threaded is provided in a straight tube portion of an exhaust manifold of an internal combustion engine for a motorcycle that is a scooter-type vehicle. Such a fastening portion is welded to the straight tube portion of the exhaust manifold, and a threaded portion (a female thread) corresponding to a threading portion (a male thread) of the oxygen concentration sensor is provided on an inner circumferential surface of the fastening portion. Such a fastening portion is welded obliquely to the straight tube portion of the exhaust manifold, and in the fastened state, a protective side (an oxygen sensing side) of the oxygen concentration sensor is inserted obliquely into the exhaust manifold from an upstream side to a downstream side of the exhaust gas. That is, a side Petition 870250073563, dated 08 / 20 / 2025, pp. 65 / 94 2 / 30 of the output signal line (one wiring side) of the oxygen concentration sensor is located on one side of the engine cylinder head. This makes it possible to reduce exhaust gas flow path resistance in the exhaust manifold and perform accurate oxygen concentration measurement without impeding exhaust gas flow. State of the art document Patent document

[004] Patent document 1: JP 2006-170938 A Summary of the Invention Underlying problems to be solved by the invention

[005] In emissions improvement, incidentally, there is a demand for further improvement in the detection accuracy of the exhaust gas sensor such as the oxygen concentration sensor above. For example, when the above fastening portion is used to fix the exhaust gas sensor, in other words, a connecting portion is provided by welding it to the exhaust pipe, the welding is performed continuously over the entire circumference of this connecting portion, and the welding is performed to achieve a position that overlaps a welding start portion. That is, in welding, the welding start portion and a welding end portion overlap each other. For this reason, in the welding start portion (i.e., the welding end portion) a weld bead can be thicker than the other portions. Consequently, the weld bead, i.e., the weld bead, can easily appear inside the exhaust pipe.Depending on the amount of protrusion of this posterior cord, the flow of exhaust gas towards the exhaust gas sensor can be influenced. In particular, in a case where the exhaust gas sensor is arranged obliquely with respect to the exhaust flow direction, the amount of protrusion on one end of the tip can affect the flow. Petition 870250073563, dated 08 / 20 / 2025, pp. 66 / 94 3 / 30 A sensor detection unit inside the exhaust passage is smaller than that of a case where the exhaust gas sensor is positioned at a right angle to the exhaust flow direction. Therefore, the influence of the back bead on the exhaust gas flow can still significantly determine the detection capability.

[006] So, with regard to the influence of the downstream corrugation on the exhaust gas sensor, particular consideration is desirably given to the exhaust gas sensor provided on the downstream side of the exhaust gas purification catalyst in the exhaust passage of the internal combustion engine. This is because the exhaust gas passes through the exhaust gas purification catalyst, and therefore the exhaust gas flow is easily disturbed by the influence of exhaust pressure in some cases. The detection of exhaust gas components by the exhaust gas sensor provided on the downstream side of the exhaust gas purification catalyst may be more difficult than detection by the exhaust gas sensor provided on the downstream side of the exhaust gas purification catalyst.

[007] One object of the present invention is to provide, in an exhaust device for an internal combustion engine mounted on a vehicle of the type to be mounted such as a motorcycle, a configuration capable of reducing the influence of a weld bead of a connecting portion of an exhaust gas sensor on the detection accuracy of the exhaust gas sensor, in a case where the exhaust gas sensor is provided to be obliquely inclined with respect to an exhaust passage, on a downstream side of an exhaust gas purification catalyst. This contributes, therefore, to lessening the climatic changes or reducing the influence. A means to solve problems

[008] To achieve the above objective, according to an aspect of the present Petition 870250073563, dated 08 / 20 / 2025, pp. 67 / 94 4 / 30 invention, an exhaust device for an internal combustion engine mounted in a vehicle of the mounting type is provided, the exhaust device including: an exhaust gas purification catalyst provided in an exhaust passage of the internal combustion engine; and an exhaust gas sensor provided in a downstream exhaust passage on a downstream side of the exhaust gas purification catalyst, wherein the exhaust gas sensor is provided in a connecting portion welded to an exhaust pipe that defines and forms the downstream exhaust passage, such that the exhaust gas sensor is inclined obliquely with respect to an exhaust flow direction and a welding start portion in a weld portion around the connecting portion to be connected to the exhaust pipe is located on a non-upstream side in the exhaust flow direction of the exhaust gas sensor.

[009] According to the configuration above, the welding initiation portion is located on the non-upstream side in the exhaust flow direction of the exhaust gas sensor. Therefore, the welding initiation portion is not located on the upstream side of the exhaust gas sensor, and it becomes possible to suppress the weld bead on the upstream side of the downstream exhaust gas sensor from becoming thick, so that the exhaust gas flow from the exhaust gas purification catalyst towards the downstream exhaust gas sensor can be maintained more adequately. Therefore, in the vehicle-mounted internal combustion engine exhaust device of the mounting type, it becomes possible to reduce the influence of the weld bead of the downstream exhaust gas sensor connection portion on the detection accuracy of the downstream exhaust gas sensor on the downstream side of the catalyst. Petition 870250073563, dated 08 / 20 / 2025, pp. 68 / 94 5 / 30 of exhaust gas purification. Therefore, the detection accuracy of the exhaust gas sensor can be improved.

[010] In a case where a virtual plane is defined to pass through an intersection point between an extension plane of an exhaust pipe surface and an axis of the connection portion and is orthogonal to the exhaust flow direction, the welding start portion is preferably located on a downstream side in the exhaust flow direction of the virtual plane. According to this configuration, the welding start portion in the weld portion around the connection portion can be more safely located on the non-upstream side in the exhaust flow direction of the exhaust gas sensor.

[011] The welding initiation portion is preferably located in a region one width downstream of the connection portion. According to this configuration, the welding initiation portion in the weld portion around the connection portion can be more safely located on the downstream side in the exhaust gas sensor's exhaust flow direction. This allows for additional suppression of the exhaust gas flow impediment influence of the weld bead, and thus allows for further improvement in the downstream exhaust gas sensor's detection accuracy.

[012] In a case where a virtual plane is defined to pass through an intersection point between an extension plane of an exhaust pipe surface and an axis of the connecting portion and is orthogonal to the exhaust flow direction, an inclination of an axis of the exhaust gas sensor with respect to the virtual plane is preferably equal to or greater than 10 degrees and equal to or less than 45 degrees. According to this configuration, the sensor sensing unit of the exhaust gas sensor can be sufficiently separated from the inner wall surface of the exhaust pipe and the sensor sensing unit itself becoming the exhaust flow resistance can also be Petition 870250073563, dated 08 / 20 / 2025, pp. 69 / 94 6 / 30 effectively suppressed.

[013] The exhaust gas sensor preferably includes a sensor sensing unit located in the exhaust passage and a sensor body portion extending on the outside of the exhaust passage, and the sensor sensing unit may be located on a downstream side in the exhaust flow direction of the sensor body portion. According to this configuration, the sensor sensing unit of the exhaust gas sensor may be arranged along the exhaust flow direction. Therefore, even if the exhaust gas flow velocity around the exhaust gas sensor is very high, the exhaust gas pressure loss by the exhaust gas sensor may be reduced.

[014] The purification device preferably includes the exhaust gas purification catalyst in an interior, the purification device having a main body portion in which a carrier carrying the exhaust gas purification catalyst is disposed, and a reduced diameter portion connected to a downstream side in the exhaust flow direction of the main body portion and reducing in diameter towards the downstream side in the exhaust flow direction and the connection portion may be located on the downstream side in the exhaust flow direction of the reduced diameter portion, the exhaust gas sensor including a sensor sensing unit located in the exhaust passage and a sensor body portion extending into an exterior of the exhaust passage, the sensor sensing unit being located on the downstream side in the exhaust flow direction of the sensor body portion.According to this configuration, the exhaust gas sensor can be located on the downstream side of the reduced-diameter portion of the purification device, and the exhaust gas sensor's detection unit can be arranged along the exhaust flow direction. Petition 870250073563, dated 08 / 20 / 2025, pp. 70 / 94 7 / 30 Therefore, even if the flow velocity of the exhaust gas that has passed through the purification device and then flows around the downstream exhaust gas sensor is very high, the pressure loss of the exhaust gas through the downstream exhaust gas sensor can be reduced. Effects of the invention

[015] According to an aspect above of the present invention, with the provision of the above configuration, in the exhaust device for the internal combustion engine mounted on the vehicle of the mounting type, it becomes possible to reduce the influence of the weld bead of the connecting portion of the exhaust gas sensor on the detection accuracy of the exhaust gas sensor, in a case where the exhaust gas sensor is provided to be obliquely inclined with respect to an exhaust passage on a downstream side of an exhaust gas purification catalyst. Brief description of the drawings

[016] Figure 1 is a left side view of a motorcycle which is a ride-type vehicle according to an embodiment of the present invention.

[017] Figure 2 is a front view of a part of the motorcycle in Figure 1.

[018] Figure 3 is a bottom view of a part of the motorcycle in Figure 1.

[019] Figure 4 is a view illustrating a part of an exhaust device for an internal combustion engine of the motorcycle of Figure 1 according to a modification.

[020] Figure 5 is an enlarged perspective view of an exhaust gas sensor from the exhaust device for the internal combustion engine in the motorcycle of Figure 1 and a periphery of its mounting portion. Petition 870250073563, dated 08 / 20 / 2025, pp. 71 / 94 8 / 30

[021] Figure 6 is an enlarged view of the exhaust gas sensor and a periphery of its mounting portion on the exhaust device that is separated from the motorcycle in Figure 1.

[022] Figure 7 is an enlarged cross-sectional view of the periphery of the exhaust gas sensor illustrated in Figure 6.

[023] Figure 8 is a view of the exhaust gas sensor as viewed from a cut surface of an exhaust pipe that is cut on a downstream side of the exhaust gas sensor illustrated in Figure 6.

[024] Figure 9 is a schematic cross-sectional view of a weld portion when two plate members are welded together by arc welding.

[025] Figure 10 is a plan view of a periphery of a connection portion of the exhaust gas sensor illustrated in Figure 6 and is a schematic view illustrating a welding start portion in a welding portion around the connection portion and a welding direction from the welding start portion. Methods for carrying out the invention

[026] Next, a motorcycle 10, which is a ride-on type vehicle according to an embodiment of the present invention, will be described with reference to the attached drawings. Here, the upper, lower, front, rear, right and left sides of the vehicle body are defined based on the line of sight of a driver seated on the motorcycle 10. In the drawings, the reference sign “UP” is used for an upper side in an up-down direction, the reference sign DW is used for a lower side, the reference sign FR is used for a front side in a front-to-rear direction of a vehicle, the reference sign RR is used for a rear side, and the reference sign RH is used for a right side in a width direction. Petition 870250073563, dated 08 / 20 / 2025, pp. 72 / 94 9 / 30 vehicle and the reference sign “LH” is used for the left side.

[027] Figure 1 is a left side view of motorcycle 10, that is, a side view on the right side of the vehicle body. Figure 2 is a front view, that is, it illustrates a front surface of a part of motorcycle 10. Figure 3 is a bottom view of a part of motorcycle 10 from figure 1.

[028] The motorcycle 10 includes: a power unit; and a vehicle structural frame 12, on which electrical components are mounted. A main tube (not illustrated) on the vehicle structural frame 12 extends rearward from a collector tube 14, which is located on a front end portion. A fuel tank 18, inside which fuel is stored, is arranged on a rear side of the collector tube 14. A seat 20, on which a driver sits, is mounted on a rear side of the fuel tank 18. A footrest 22, which serves as a footrest for a driver to place their foot while driving, is provided below the seat 20.

[029] A brake pedal 24 for a rear wheel WR, which is a drive wheel, is provided in close proximity to the footrest 22, on the right side of the vehicle body illustrated in Figure 1. In the brake pedal 24, a rear end portion 24r, which is located on a rear side of the footrest 22, is pivotally supported, and a front end portion 24f, which is located on a front side relative to the footrest 22, is provided to be oscillating up and down. In a side view of the motorcycle 10 in Figure 1, the brake pedal 24 is shaped to extend first substantially horizontally from the rear end portion 24r towards the front end portion 24f and then be slightly inclined forward and upward. That is, the brake pedal 24 extends in a front-to-rear direction without being substantially Petition 870250073563, dated 08 / 20 / 2025, pp. 73 / 94 10 / 30 inclined in an up-down direction in a side view of the motorcycle 10. The front end portion 24f of the brake pedal 24 functions as a pedal portion, is located on a right side of a front end side portion of a crankcase 30 to be described later, is also located at substantially the same height as the footrest 22 and can be stepped on to be operated by the driver's foot placed on the footrest 22.

[030] Additionally, in the vicinity of the footrest 22 on the right side of the vehicle body illustrated in figure 1, in particular, a kickstart pedal 25 is provided on an upper side of the footrest 22. The kickstart pedal 25 includes a rear end portion 25r, which is located on a substantially upper side of the footrest 22; and a front end portion 25f, which is located in the vicinity of a rear portion of a cylinder head 34 of a main engine body 26 of an internal combustion engine E of the power unit. The kickstart pedal 25 first extends upwards towards the front end portion 25f from the rear end portion 25r, and is then curved forward. The kickstart pedal 25 is unfolded to extend outwards in the direction of the vehicle's width when used. The front end portion 25f of the kickstart pedal 25 functions as a pedal portion, and is stepped on by the driver's foot.Stepping on it in this way causes the kickstart pedal 25 to rotate within a predetermined range around the rear end portion 25f, and is able to start the internal combustion engine E.

[031] The main engine body 26 of the internal combustion engine E is suspended above the main tube in the vehicle structural frame 12. The main engine body 26 includes: the crankcase described above, 30; a cylinder block 32; a cylinder head 34; and a cylinder head cover 36, which are Petition 870250073563, dated 08 / 20 / 2025, pp. 74 / 94 11 / 30 sequentially supplied above the crankcase 30. The cylinder block 32 in a forward-inclined state is coupled to an upper side of the crankcase 30. Therefore, as illustrated in Figure 1, a cylinder shaft C of the main engine body cylinder 26 is obliquely forward-inclined from the crankshaft of the crankcase 30 towards the cylinder head 34. Note that the crankshaft extends in the width direction of the vehicle and is substantially orthogonal to the up-down and front-to-back directions. In Figure 1, a rotation axis 38 of the crankshaft is illustrated.

[032] An upper end (an upstream end) of an exhaust pipe 40 of the exhaust device 39 for the internal combustion engine E is connected to the cylinder head 34 of the main engine body 26. The exhaust gas discharged from the combustion chamber (not shown) flows through the exhaust pipe 40 and is discharged from a muffler 42 which is located on a right-hand side of the rear wheel WR, i.e., located on a right-hand side of the vehicle body. Exhaust gas sensors 44 and 46 and a purification device 48 are provided on the front end side, i.e., on a side upstream of the muffler 42. Note that a cylinder head exhaust port 34, exhaust pipe 40, purification device 48, an exhaust pipe 50, and the muffler 42 are connected in that order in an exhaust flow direction and each of them defines a part of an exhaust passage 52.

[033] Note that a front fork 54 is supported rotationally on a front end portion of the head tube via a steering shaft provided in the collector tube 14. A handlebar 56 is provided on an upper end portion of the steering shaft and grips 58 are respectively fixed on both end portions of the handlebar 56. A front wheel WF is supported rotationally by lower portions of the Petition 870250073563, dated 08 / 20 / 2025, pp. 75 / 94 12 / 30 front fork 54. One upper side of the WF front wheel is partially covered with a 60 front fender.

[034] Furthermore, the rear wheel WR, to which dynamic energy from the internal combustion engine E is transmitted, is rotationally supported on a rear side of the main engine body 26 by means of a swing arm. A suspension 62, which dampens an impact from a road surface, is arranged between the swing arm and the vehicle's structural frame 12. A rear fender 64 is arranged on a rear upper side of the rear wheel WR, that is, on a rear side of the seat 20.

[035] As described above, incidentally, the exhaust pipe 40 of the exhaust device 39 is connected to a front wall of the cylinder head 34 of the main engine body 26 and the purification device 48 and the silencer 42 are arranged on the downstream side sequentially from the upstream side. The purification device 48 is configured to have a function of purifying the exhaust gas and particularly accommodates an exhaust gas purification catalyst 48a within it, i.e., it includes a carrier 48b, which carries the catalyst 48a. Here, the carrier 48b includes a honeycomb base material in which a plurality of cells, extending from an influx end face (an upstream end face) to an exhaust gas outlet end face (a downstream end face), are divided and formed by porous partition walls.Catalyst 48a is transported in the partition walls of this honeycomb base material. Here, catalyst 48a is a three-way catalyst (TWC) and has a function (i.e., a three-way purification function) of purifying HC in the exhaust gas by oxidizing or reducing HC in the exhaust gas to H2O and CO2, CO to CO2, and NOx to N2. Carrier 48b is made, for example, of an oxide such as alumina, silica, zirconia, titania, ceria, or zeolite, and the catalyst is made of... Petition 870250073563, dated 08 / 20 / 2025, pp. 76 / 94 13 / 30 three-way alloys contain, for example, precious metals such as platinum, palladium, or rhodium.

[036] In exhaust passage 52, exhaust gas sensor 44 is provided in an exhaust passage (an upstream exhaust passage) 52a on the upstream side of the purification device 48 and exhaust gas sensor 46 is provided in an exhaust passage (a downstream exhaust passage) 52b on the downstream side of the purification device 48. Here, exhaust gas sensors 44 and 46 are each an oxygen (O2) sensor that emits a signal corresponding to the oxygen concentration in the exhaust gas, but it could be, for example, an LAF sensor (linear air-fuel ratio sensor) which is a type of air-fuel ratio sensor. The silencer 42 is configured to have a silencing function.

[037] As illustrated in Figure 1, the exhaust passage 52, which is continuous from the exhaust port of the cylinder head 34 of the main engine body 26, extends on a front side of the main engine body 26, that is, it extends outwards, then extends downwards, extends further backwards passing under the main engine body 26 and extends until it reaches the right side of the rear wheel WR. That is, the exhaust device 39 extends from the front side of the main engine body 26 of the internal combustion engine E to the lower side and extends on the right rear side passing on the lower right side of the main engine body 26. As illustrated in Figures 1 to 3, the purifier device 48 is located on the lower right side of the main engine body 26 in a lower part of the vehicle and is particularly located on the lower side of the crankcase 30.The purification device 48 is arranged to extend substantially horizontally below the main engine body 26 in Figure 1. Therefore, as illustrated in the front view of motorcycle 10 in Figure 2 and the bottom view of motorcycle 10 in Figure 3, in a case where a central virtual plane CIS extends into... Petition 870250073563, dated 08 / 20 / 2025, pp. 77 / 94 14 / 30 center in the left-right direction from the front towards the rear of the motorcycle 10 is defined, the purification device 48 is located on its right side and is provided on the motorcycle 10 so that a downstream portion of the purification device 48 is oriented slightly outwards in the direction of vehicle width than an upstream portion. Note that the central virtual plane CIS can be defined as being orthogonal to the direction of vehicle width and also divides each front wheel WF and rear wheel WR substantially into two parts.

[038] The exhaust pipe 50, which defines and forms the downstream exhaust passage 52b extending rearward from the purifier device 48, extends rearward from a downstream end portion of the purifier device 48 on the lower right rear side of the crankcase 30 of the main engine body 26. In the side view of Figure 1, the exhaust pipe 50 is provided to extend in the front-to-rear direction of the vehicle substantially along the brake pedal 24. As illustrated in Figures 1 to 3, the exhaust pipe 50 extends to be slightly inclined upward and also slightly inclined to the outside of the vehicle from the upstream end portion connected to the purifier device 48 towards the downstream side in the exhaust flow direction, i.e., the rear side of the vehicle, and is then connected to the muffler 42.The muffler 42 extends in the front-to-rear direction of the vehicle on the right side of the WR rear wheel and is arranged to be slightly angled upwards towards the downstream side in the direction of exhaust flow.

[039] The exhaust gas sensor described above (hereinafter, the downstream exhaust gas sensor) 46 on the downstream side of the purification device 48 is provided in the exhaust pipe 50, which defines and forms the downstream exhaust passage 52b which is an exhaust passage on the downstream side of the purification device 48. Here, as illustrated in figure 1, the exhaust gas sensor a Petition 870250073563, dated 08 / 20 / 2025, pp. 78 / 94 15 / 30 downstream 46 is disposed, on an upper side of the exhaust pipe 50, in a position closer to the rear end portion 24r between the rear end portion 24r and the front end portion 24f of the brake pedal 24. Furthermore, as illustrated in figures 2 and 3, the downstream exhaust gas sensor 46 is located on an upper inner side of the exhaust pipe 50. Therefore, in the front view of the motorcycle 10 in figure 2, a connecting portion 70 of the downstream exhaust gas sensor 46 to the exhaust pipe 50 is hidden behind the purifier device 48, and the downstream exhaust gas sensor 46 is also partially hidden behind the purifier device 48. Therefore, it becomes possible to adequately protect the downstream exhaust gas sensor 46 from a flying object such as a stone that has rapidly risen up past the front wheel WF.Additionally, as illustrated in Figure 1, the downstream exhaust gas sensor 46 is provided in the exhaust pipe 50 so as to be inclined obliquely with respect to the direction of exhaust flow. Thus, in the front view of the motorcycle 10 in Figure 2, the amount of protrusion of the downstream exhaust gas sensor 46 from the exhaust pipe 50 is less than that in the case of it being fixed in the exhaust pipe 50 at a right angle to the direction of exhaust flow. Therefore, it becomes possible to more adequately protect the downstream exhaust gas sensor 46 from a flying object.

[040] As illustrated in Figure 1, the downstream exhaust gas sensor 46, which is disposed on the upper inner side of the exhaust pipe 50 to be concealed on the rear side of the purification device 48, is located on the rear side of and slightly below the footrest 22, extending substantially parallel to the purification device 48 so as to project onto an outer right side of the purification device 48. Therefore, it becomes possible to adequately protect the downstream exhaust gas sensor 46 on an inner side of the driver's footrest without being influenced by the driver's operation. Petition 870250073563, dated 08 / 20 / 2025, pp. 79 / 94 16 / 30 on the brake pedal 24.

[041] Note that in figures 1 to 3, it is possible to visually recognize the exhaust gas sensor 46 from outside the vehicle body, so that the feasibility of fixing and feasibility of maintenance can be satisfactorily maintained.

[042] Here, the exhaust gas sensor described above (hereinafter, the upstream exhaust gas sensor) 44, which is provided in the exhaust passage 52a on the upstream side of the purification device 48, is fixed in the cylinder head 34. The upstream exhaust gas sensor 44 is capable of detecting the oxygen concentration of the exhaust gas in the exhaust port defined and formed in the cylinder head 34. However, the upstream exhaust gas sensor 44 is not limited to being provided for the exhaust port, and may be provided in the exhaust pipe 40 as illustrated in Figure 4. Figure 4 is a view illustrating the exhaust pipe 40, the purification device 48 and the exhaust pipe 50, which define and form, respectively, portions of the exhaust passage 52 extending from the main engine body 26 of the internal combustion engine E.Unlike the exhaust device 39 for the internal combustion engine E illustrated in figure 1, figure 4 illustrates the upstream exhaust gas sensor 44, which is provided in the exhaust pipe 40 according to a modification. Thus, the upstream exhaust gas sensor 44 can be provided in any position between the exhaust port position and an upstream end of a main body portion 48d of the purification device 48, in which the carrier 48b for carrying the exhaust gas purification catalyst 48a is accommodated.

[043] Note that a control device, i.e., an ECU (engine control unit) for the E internal combustion engine or similar is not illustrated, but it is mounted on the motorcycle 10 and has a configuration such as Petition 870250073563, dated 08 / 20 / 2025, pages 80 / 94 17 / 30 a computer. That is, the ECU includes a processor (e.g., CPU) and memory (e.g., ROM and RAM). Output signals from various sensors are entered into the ECU. For example, in addition to engine load sensors such as an engine speed sensor and a throttle opening sensor, the upstream exhaust gas sensor 44 and the downstream exhaust gas sensor 46, which were described above, are connected to the ECU. The ECU analyzes operating states based on the inputs from these sensors and controls, for example, the respective operations of a fuel injection valve, a spark plug, and a throttle valve, which are not illustrated, based on the analyzed operating states.For example, the ECU controls fuel injection from the fuel injection valve so that the purification device 48 properly purifies the exhaust gas, based on inputs respectively from the upstream exhaust gas sensor 44 and the downstream exhaust gas sensor 46 (or outputs from them). However, the throttle valve is not limited to an electronic control type and may have a mechanical operation type configuration.

[044] As described above, the downstream exhaust gas sensor 46 is provided in the exhaust pipe 50 so as to be obliquely inclined with respect to an exhaust flow direction EF. Figure 5 is an enlarged perspective view of the downstream exhaust gas sensor 46 and the periphery of its mounting portion. The downstream exhaust gas sensor 46 is provided in the connection portion 70, which is welded to the exhaust pipe 50 defining and forming the downstream exhaust passage 52b, so that the downstream exhaust gas sensor 46 is obliquely inclined with respect to the exhaust flow direction EF. The connection portion 70 indicates a connecting member, i.e., a connecting support, here more specifically, a raised member having a tubular shape, includes a direct bore 70h (see Figure 7) having a shaft Petition 870250073563, dated 08 / 20 / 2025, pp. 81 / 94 18 / 30 70a and serves as an insert member weld. As illustrated in Figure 5, the connecting portion 70 is connected to a fixing hole 50h of the exhaust pipe 50 by welding, here, arc welding. A weld bead 70b, extending over the entire circumference of the connecting portion 70, is formed around the connecting portion 70 so as not to leave a gap between the connecting portion 70 and the exhaust pipe 50.

[045] Here, Figure 6 is an enlarged view of the downstream exhaust gas sensor 46 and the periphery of its attachment portion on the exhaust device 39, which is removed from the motorcycle 10, and Figure 7 is an enlarged cross-sectional view of the periphery of the downstream exhaust gas sensor 46. However, in Figures 6 and 7, the weld bead 70b is omitted, and in Figure 7, the downstream exhaust gas sensor 46 is not illustrated in cross-section. Furthermore, Figure 8 is a view of the exhaust gas sensor 46 as seen from a cut surface of the exhaust pipe 50, which is cut at a position on a downstream side of the downstream exhaust gas sensor 46 illustrated in Figure 6.

[046] A threaded portion (a female threaded portion) 70c for securing the downstream exhaust gas sensor 46 is formed in the connecting portion 70 on an inner circumferential surface 70i, which defines and forms the direct bore 70h having a substantially cylindrical shape extending straight. A threaded portion (a male threaded portion) 46b corresponding to the threaded portion 70c is formed on an outer circumference of the downstream exhaust gas sensor 46. Thus, the downstream exhaust gas sensor 46 is threaded (tappled) into the connecting portion 70. In this situation, a stop portion 46c, which projects annularly in the radial direction of the downstream exhaust gas sensor 46, contacts and then rests on a stop portion 70d of the connecting portion 70. The downstream exhaust gas sensor 46 is fixed to the connecting portion 70 in this way, and thus a shaft 46a of the exhaust gas sensor is attached. Petition 870250073563, dated 08 / 20 / 2025, pp. 82 / 94 19 / 30 downstream exhaust 46 coincides with axis 70a of the straight bore 70h, which is defined and formed by the inner circumferential surface 70i of the connecting portion 70. Furthermore, its axes 46a and 70a intersect an axis 50a that extends in the exhaust flow direction EF of the exhaust pipe 50. Therefore, here, the portion of the exhaust pipe 50 over which the connecting portion 70 is provided is a pipe portion (a straight pipe portion) that extends substantially straight, and thus the axis 50a of the exhaust pipe 50, the axis 70a of the connecting portion 70, and the axis 46a of the downstream exhaust gas sensor 46 extend substantially in an identical plane. Note that axes 46a and 70a may extend so as not to intersect axis 50a of exhaust pipe 50, that is, not to intersect at a point and be separated by a distance within a certain permissible range.

[047] The connecting portion 70 is obliquely welded to the exhaust pipe 50 and includes a pointed end fastening portion 70e, which is formed so that the axis 70a is inclined with respect to the exhaust flow direction EF of the downstream exhaust passage 52b. The pointed end fastening portion 70e is curved along the curved shape of the exhaust pipe 50, having a substantially circular cross-section, and has a concave curved surface inclined with respect to the axis 70a. The pointed end fastening portion 70e is located to be closer to the exhaust pipe 50 than the abutting portion 70d in the direction of the axis 70a of the connecting portion 70 and is located in an end portion, i.e., a pointed end portion of the connecting portion 70 in the direction of the axis 70a. Note that the other end portion of the connecting portion 70 in the direction of axis 70a is the abutting portion described above 70d.The circumference of the end-tip fastening portion 70e is welded, and thus the connecting portion 70 is fixed to the hole 50h of the exhaust pipe 50 so that the connecting portion 70 does not project into the downstream exhaust passage 52b. Petition 870250073563, dated 08 / 20 / 2025, pages 83 / 94 20 / 30

[048] The exhaust gas sensor 46 is fixed to the connection portion 70 which is fixed to the exhaust pipe 50; thus, a sensor sensing unit 46d at its tip end is located in the downstream exhaust passage 52b and a sensor body portion 46e including the above-described backing portion 46c extends outside the downstream exhaust passage 52b. Then, the inclination of the downstream exhaust gas sensor 46 with respect to the exhaust flow direction EF is determined so that the sensor sensing unit 46d is located on a downstream side in the exhaust flow direction EF of the sensor body portion 46e. This allows the provision of the sensor sensing unit 46d in the downstream exhaust passage 52b of the exhaust pipe 50 so as to smoothly follow the exhaust gas flowing in the exhaust flow direction EF.

[049] With regard to the inclination of the downstream exhaust gas sensor 46, in a case where a virtual plane EIS is defined as being orthogonal to the exhaust flow direction EF as illustrated in figure 7, an inclination θ of the axis 46a of the downstream exhaust gas sensor 46 with respect to such virtual plane EIS may be equal to or greater than 10 degrees and equal to or less than 45 degrees. In consideration of the bore 50h of the exhaust pipe 50, the virtual plane EIS may be determined to pass through an intersection point CP between an extension plane of a surface 50s of the exhaust pipe 50 and the axis 70a of the connecting portion 70 and be orthogonal to the exhaust flow direction EF.By setting the slope θ to 10 degrees or more, it becomes possible to reduce the amount of protrusion of the sensor sensing unit 46d into the downstream exhaust passage 52b, compared to a case where the slope θ is less than 10 degrees, and it becomes possible to suppress the sensor sensing unit 46d from becoming resistant to the exhaust gas flow. Furthermore, by setting the slope θ to 45 degrees or more, it becomes possible... Petition 870250073563, dated 08 / 20 / 2025, pp. 84 / 94 21 / 30 ensure that the distance is equal to or longer than a predetermined distance between the sensor detection unit 46d and the exhaust pipe itself 50 or the weld bead 70b, i.e., a back bead B to be described later, compared to a case where the inclination θ is set at an angle greater than 45 degrees.

[050] Furthermore, as illustrated in figure 6, the connecting portion 70 is provided to locate the sensor sensing unit 46d of the downstream exhaust gas sensor 46 at a distance separated by a predetermined distance range (a first predetermined distance range) in the exhaust flow direction EF from a downstream end 48c of the carrier 48b carrying the exhaust gas purification catalyst 48a of the purification device 48. The first predetermined distance range can be defined as a range that allows the sensor sensing unit 46d of the downstream exhaust gas sensor 46 to be located in a region where the exhaust gas that has passed through the purification device 48, i.e., the exhaust gas purification catalyst 48a, is uniformly diffused to a certain point in the downstream exhaust passage 52b.Additionally, it is sufficient to determine the first predetermined distance range so that the heat from the exhaust gas purification catalyst 48a, i.e., the carrier 48b for transporting the purification device 48, does not affect the downstream exhaust gas sensor 46. Here, the purification device 48 includes: the main body portion 48d in which the carrier 48b carrying the exhaust gas purification catalyst 48a is arranged; and a reduced diameter portion 48e, which is connected to the downstream side in the exhaust flow direction EF of the main body portion 48d, and which is reduced in diameter towards the downstream side in the exhaust flow direction EF. Therefore, it is sufficient to define the first distance range. Petition 870250073563, dated 08 / 20 / 2025, pages 85 / 94 22 / 30 predetermined at a distance by which the sensor detection unit 46d of the downstream exhaust gas sensor 46 is located on a downstream side of the reduced diameter portion 48e. Note that the first predetermined distance range can be determined in association with the average diameter of the exhaust pipe 50, however, if limited to this, it can be determined according to, for example, the shape of the exhaust pipe 50, the size of the motorcycle 10 and / or the size of the internal combustion engine E.

[051] Additionally, connection portion 70 is provided to locate the sensor sensing unit 46d of the downstream exhaust gas sensor 46 at a position separated by a distance in a second predetermined distance range in the exhaust flow direction EF from a drain hole 51h to remove condensed water in the exhaust passage 52. As illustrated in Figure 1, the drain hole 51h is provided on a downstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46 and is provided in the vicinity of the upstream end of the muffler 42. Note that the drain hole 51h may be provided in the exhaust pipe 50. Atmosphere may enter from the drain hole 51h. If the downstream exhaust gas sensor 46 is too close to the drain hole 51h, the downstream exhaust gas sensor 46 will be influenced by the oxygen in the atmosphere that has entered. For this reason, the second predetermined distance range is determined to reduce this influence.The second predetermined distance range can be defined to allow for a compact arrangement of the downstream exhaust gas sensor 46 on the motorcycle 10. Note that the second predetermined distance range can be determined in association with the average diameter of the exhaust pipe 50, but without being limited to this, it can be determined according to, for example, the shape and / or arrangement of the exhaust pipe 50.

[052] In arc welding to connect the connecting portion 70 with the Petition 870250073563, dated 08 / 20 / 2025, pages 86 / 94 23 / 30 exhaust pipe 50, by the way, the weld bead 70b is normally generated not only on the front side (on the outside of the exhaust pipe 50) where the electrode is located, but also on the back side (on the inside of the exhaust pipe 50). For example, Figure 9 illustrates a schematic cross-sectional view of a weld portion in which two plate members M1 and M2 are welded together by arc welding. In Figure 9, plate members M1 and M2 are welded together by arc welding and a weld bead MB is formed between plate members M1 and M2. In Figure 9, in a case where an upper surface MU is defined as a front side, i.e., a welding operation side, it can be seen that the weld bead MB also projects onto a lower surface MD on the opposite side in Figure 9.

[053] Such a weld bead on the back side, that is, the back bead B, can also be formed when the connection portion 70 is welded to the exhaust pipe 50. In particular, when welding the connection portion 70 having a tubular shape, the weld bead 70b, which is continuous around the connection portion 70, is formed. As schematically illustrated in Figure 10, the weld bead 70b starts from a welding start portion B1, is formed continuously around the connection portion 70 from the welding start portion B1, and ends in a welding end portion B2 that overlaps the welding start portion B1.Thus, since the weld start portion B2 overlaps the weld end portion B2, there is a possibility that the weld bead 70b in the weld start portion B1 will be thicker than those in the other portions, the rear bead B in the weld start portion B1 will also be thicker than those in the other portions, and the amount of protrusion into the exhaust pipe 50 will be greater than in the other portions. For this reason, also in a case where the weld bead 70b is formed and the rear bead B is formed... Petition 870250073563, dated 08 / 20 / 2025, pages 87 / 94 24 / 30 projects around the connection portion 70, that is, in an internal region 50hi of the fixing hole 50h as illustrated in figure 8, here, the welding start portion B1 in a welding portion 70W around the connection portion 70 to be connected to the exhaust pipe 50 is located on a non-upstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46 to reduce the influence of the back bead B on the detection accuracy of the downstream exhaust gas sensor 46 (see figure 10). Note that “non-upstream side” indicates any side other than the upstream side of the downstream exhaust gas sensor 46 in the exhaust flow direction EF.For example, the welding start portion B1 on the non-upstream side of the downstream exhaust gas sensor 46 can be set in a position where the exhaust gas does not directly reach the sensor detection unit 46d when the exhaust gas passes around the back bead in the welding start portion B1 in the exhaust flow direction EF. Note that in Figure 10, the welding direction from the welding start portion B1 is indicated by a clockwise arrow A1, but without being limited to this, the welding direction can be counterclockwise.

[054] Specifically here, the welding start portion B1 passes through the intersection point CP between an extension plane of the exhaust pipe surface 50 and the axis 70a of the connection portion 70 and is located on the downstream side in the exhaust flow direction EF relative to the virtual plane above EIS (see figure 7) which is defined as being orthogonal to the exhaust flow direction EF. That is, in figure 10, in the exhaust flow direction EF, the welding start portion B1 is located on the downstream side of the virtual plane EIS.

[055] Furthermore, in the present embodiment, to more safely avoid the influence of the back bead B on the position of the welding start portion B1, the welding start portion B1 is located in a region Petition 870250073563, dated 08 / 20 / 2025, pages 88 / 94 25 / 30 within a downstream width 70r of the connection portion 70. As illustrated in Figure 10, in a case where the length of the connection portion 70 in the direction orthogonal to the exhaust flow direction EF is defined as the width of the connection portion 70, that is, the downstream width 70r, the region at the downstream width 70r of the connection portion 70 indicates a region that extends to the downstream side of the connection portion 70 at the width 70r of the connection portion 70, in the exhaust flow direction EF.

[056] A characteristic configuration of the exhaust device 39 for the internal combustion engine E in the motorcycle 10 having the above configuration, and its operation and effects will be described below.

[057] In the internal combustion engine E, which is mounted on the motorcycle 10 of a ride-on type vehicle, the exhaust device 39 is connected to the main engine body 26. The exhaust device 39 includes the exhaust gas purification catalyst 48a, which is provided in the exhaust passage 52, and the downstream exhaust gas sensor 46, which is provided in a downstream exhaust passage 52b on the downstream side of the exhaust gas purification catalyst 48a. The downstream exhaust gas sensor 46 is provided in the connection portion 70, which is welded to the downstream exhaust pipe 50, defining and forming the downstream exhaust passage 52b, so that the downstream exhaust gas sensor 46 is obliquely inclined with respect to the exhaust flow direction EF.Therefore, the welding start portion B1 on the welding portion 70W around the connection portion 70 to be connected with the exhaust pipe 50 is located on the non-upstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46. According to this configuration, the welding start portion B1 is located on the non-upstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46. Therefore, the welding start portion B1 is not located on the upstream side of the gas sensor. Petition 870250073563, dated 08 / 20 / 2025, pp. 89 / 94 26 / 30 of downstream exhaust 46 and it becomes possible to suppress the weld bead 70b on the upstream side of the downstream exhaust gas sensor 46 becoming thick, so that the exhaust gas flow from the exhaust gas purification catalyst 48a towards the downstream exhaust gas sensor 46 can be maintained more adequately. In this way, in the exhaust device 39 for the internal combustion engine E mounted on the motorcycle 10, it becomes possible to reduce the influence of the weld bead 70b of the connecting portion 70 of the downstream exhaust gas sensor 46 on the detection accuracy of the downstream exhaust gas sensor 46, on the downstream side of the exhaust gas purification catalyst 48a. Therefore, the detection accuracy of the downstream exhaust gas sensor 46 can be improved.

[058] In particular, in the present embodiment, the welding start portion B1 is located on the downstream side in the exhaust flow direction EF of the virtual plane EIS. According to this configuration, the welding start portion B1 in the welding portion 70W around the connection portion 70 can be more safely located on the non-upstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46. Therefore, the above operation and effects are obtainable.

[059] Furthermore, in the present embodiment, additionally, the welding start portion B1 is located in a region within the downstream width 70r of the connection portion 70. According to this configuration, the welding start portion B1 in the welding portion 70W around the connection portion 70 can be more safely located on the downstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46. This allows for additional suppression of the impeding influence of the exhaust gas flow by the weld bead 70b and thus allows for further improvement in the detection accuracy of the downstream exhaust gas sensor 46. Note that the starting portion of Petition 870250073563, dated 08 / 20 / 2025, pages 90 / 94 27 / 30 welding B1 is not limited to being located in the region within the downstream width 70r of the connection portion 70 and may be located in any position on the non-upstream side in the exhaust flow direction EF of the downstream exhaust gas sensor 46.

[060] Furthermore, the inclination θ of the axis 46a of the downstream exhaust gas sensor 46 with respect to the virtual plane EIS can be equal to or greater than 10 degrees and equal to or less than 45 degrees. According to this configuration, the sensor sensing unit 46d of the downstream exhaust gas sensor 46 can be sufficiently separated from the inner wall surface 50i of the exhaust pipe 50 (see figure 8) and the sensor sensing unit 46d itself, becoming exhaust flow resistance, can also be effectively suppressed.

[061] The connecting portion 70 is provided for locating the sensor detection unit 46d of the downstream exhaust gas sensor 46 at a position separate from the downstream end 48c of the carrier 48b carrying the exhaust gas purification catalyst 48a by a distance comprised within a first predetermined distance range in the exhaust flow direction. According to this configuration, the downstream exhaust gas sensor 46 can be provided in a place separate from the exhaust gas purification catalyst 48a by an appropriate distance. Therefore, the exhaust gas diffused uniformly to a certain extent in the exhaust pipe 50 can be easily applied to the sensor detection unit 46d, so that the detection accuracy of the downstream exhaust gas sensor 46 can be substantially improved.Furthermore, according to this configuration, although the exhaust gas purification catalyst 48a, i.e., the purification device 48, may have a high temperature, the downstream exhaust gas sensor 46 can be appropriately separated from the catalyst. Petition 870250073563, dated 08 / 20 / 2025, pages 91 / 94 28 / 30 exhaust gas purification 48a, so that the performance of the downstream exhaust gas sensor 46 can be properly maintained.

[062] Additionally, connection portion 70 is provided to locate the sensor detection unit 46d of the downstream exhaust gas sensor 46 in a position separate from the drain hole 51h to remove condensed water in the exhaust passage 52 by a distance comprised in a second predetermined distance range in the exhaust flow direction. According to this configuration, it becomes possible to suppress the influence of atmospheric oxygen that may enter from the drain hole 51h on the downstream exhaust gas sensor 46.

[063] Additionally, the downstream exhaust gas sensor 46 further includes: the sensor sensing unit 46d, which is located in the exhaust passage 52; and the sensor body portion 46e, which extends outside the exhaust passage 52. Thus, the sensor sensing unit 46d is located on the downstream side of the sensor body portion 46e in the exhaust flow direction EF. According to this configuration, the sensor sensing unit 46d of the downstream exhaust gas sensor 46 can be arranged along the exhaust flow direction EF. Therefore, even if the exhaust gas flow velocity around the downstream exhaust gas sensor 46 is very high, the exhaust gas pressure loss by the downstream exhaust gas sensor 46 can be reduced.

[064] In addition, the purification device 48 including, within it, the exhaust gas purification catalyst 48a includes: the main body portion 48d in which the carrier 48b carrying the exhaust gas purification catalyst 48a is arranged; and the reduced diameter portion 48e, which is connected to the downstream side in the exhaust flow direction EF of the main body portion 48d, and which is reduced in diameter towards the side Petition 870250073563, dated 08 / 20 / 2025, pages 92 / 94 29 / 30 downstream in the exhaust flow direction EF. Then, the connecting portion 70 is located on the downstream side of the reduced diameter portion 48e in the exhaust flow direction EF. As described above, the downstream exhaust gas sensor 46 includes: the sensor sensing unit 46d, which is located in the exhaust passage 52; and the sensor body portion 46e, which extends outside the exhaust passage 52. The sensor sensing unit 46d is located on the downstream side of the sensor body portion 46e in the exhaust flow direction EF. According to this configuration, the downstream exhaust gas sensor 46 can be located on the downstream side of the reduced diameter portion 48e of the purification device 48 and furthermore, the sensor detection unit 46d of the downstream exhaust gas sensor 46 can be arranged along the exhaust flow direction EF.Therefore, even if the flow velocity of the exhaust gas that has passed through the purification device 48 and then flows around the downstream exhaust gas sensor 46 is very high, the pressure loss of the exhaust gas through the downstream exhaust gas sensor 46 can be reduced.

[065] Up to the present, embodiments and modifications of the present invention have been described. However, the present invention is not limited to them. Various substitutions and alterations may be made without departing from the spirit and scope of the present invention as defined by the claims of this application.

[066] The number of cylinders in the internal combustion engine fitted to the vehicle of the type to which the invention is applied is not particularly limited and the number of cylinders in the internal combustion engine may be one, i.e., a single cylinder, or it may be two or more.

[067] Note that with regard to the downstream exhaust gas sensor 46, the position of the welding start portion B1 of the welding portion 70W on the connection portion 70 was described above. The above description of the downstream exhaust gas sensor 46, for example, the position of the welding start portion B1, may Petition 870250073563, dated 08 / 20 / 2025, pages 93 / 94 30 / 30 can be similarly applied to the upstream exhaust gas sensor 44. List of reference signs Motorcycle (riding vehicle) vehicle structural frame Collector pipe Footrest Brake pedal Kickstart pedal Main engine body Oil pan Crankshaft rotation axis Escape device Exhaust pipe Silencer Exhaust gas sensor Exhaust gas sensor (downstream exhaust gas sensor) Purification device 48a Exhaust gas purification catalyst Exhaust pipe Connection portion 70b Welding cord 70W Solder Portion B1 Welding start portion B2 Welding end portion Petition 870250073563, dated 08 / 20 / 2025, page 94 / 94

Claims

1 / 3 CLAIMS 1. Exhaust device (39) for an internal combustion engine (E) mounted in a vehicle of the mounting type (10), the exhaust device (39) characterized in that it comprises: an exhaust gas purification catalyst (48a) provided in an exhaust passage (52) of the internal combustion engine (E);and an exhaust gas sensor (46) provided in a downstream exhaust passage (52b) on a downstream side of the exhaust gas purification catalyst (48a), wherein the exhaust gas sensor (46) is provided in a connecting portion (70) welded to an exhaust pipe (50) defining and forming the downstream exhaust passage (52b), such that the exhaust gas sensor (46) is inclined obliquely with respect to an exhaust flow direction (EF) and a welding start portion (B1) in a weld portion (70W) around the connecting portion (70) to be connected to the exhaust pipe (50) is located on a non-upstream side in the exhaust flow direction (EF) of the exhaust gas sensor (46).

2. Exhaust device (39), according to claim 1, characterized in that in a case where a virtual plane (EIS) is defined to pass through an intersection point (CP) between an extension plane of a surface (50s) of the exhaust pipe (50) and an axis (70a) of the connecting portion (70), and is orthogonal to the exhaust flow direction (EF), the welding start portion (B1) is located on a downstream side in the exhaust flow direction (EF) of the virtual plane (EIS).

3. Escape device (39), according to claim 1 or 2, characterized in that Petition 870250073563, dated 20 / 08 / 2025, page 54 / 94 2 / 3 the welding start portion (B1) is located in a region within a downstream width (70r) of the connection portion (70).

4. Exhaust device (39), according to any one of claims 1 to 3, characterized in that in a case where the virtual plane (EIS) is defined to pass through an intersection point (CP) between an extension plane of a surface (50s) of the exhaust pipe (50) and an axis (70a) of the connecting portion (70), and is orthogonal to the exhaust flow direction (EF), an inclination (θ) of an axis (46a) of the exhaust gas sensor (46) with respect to the virtual plane (EIS) is equal to or greater than 10 degrees and equal to or less than 45 degrees.

5. Exhaust device (39), according to any one of claims 1 to 4, characterized in that the exhaust gas sensor (46) includes a sensor sensing unit (46d) located in the exhaust passage (52) and a sensor body portion (46e) extending outside the exhaust passage (52), and the sensor sensing unit (46d) is located on a downstream side in the exhaust flow direction (EF) of the sensor body portion (46e).

6. Exhaust device (39), according to any one of claims 1 to 4, characterized in that the purification device (48) includes the exhaust gas purification catalyst (48a) in an interior, the purification device (48) having a main body portion (48d) in which a carrier (48b) carrying the exhaust gas purification catalyst (48a) is arranged, and a reduced diameter portion (48e) connected to a downstream side in the exhaust flow direction (EF) of the main body portion (48d) and reducing in diameter towards the downstream side in the exhaust flow direction (EF), and the connection portion (70) is located on the downstream side in the direction of Petition 870250073563, dated 20 / 08 / 2025, page.55 / 94 3 / 3 exhaust flow (EF) of the reduced diameter portion (48e), the exhaust gas sensor (46) including a sensor sensing unit (46d) located in the exhaust passage (52) and a sensor body portion (46e) extending into an exterior of the exhaust passage (52), the sensor sensing unit (46d) being located on the downstream side in the exhaust flow (EF) direction of the sensor body portion (46e). Petition 870250073563, dated 20 / 08 / 2025, page 56 / 94.

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