Saddle seat vehicle

Abstract

Saddle-seat vehicle that features: a motor (11); a multitude of exhaust pipes (51, 52, 53 and 54) connected to the engine (11); a merging area (60 and 260) where the multiple exhaust pipes (51, 52, 53 and 54) are joined; and an exhaust gas sensor (59), wherein the merging area (60 and 260) is arranged offset outwards in a vehicle width direction with respect to the center of a vehicle width, wherein the respective exhaust pipes (51, 52, 53 and 54) are arranged with at least three of the pipes in a bundle in order to be in contact with at least the two adjacent exhaust pipes in the merging area (60 and 260), a merging tube (55 and 255) covering the entire circumference of the merging area (60 and 260) is arranged, wherein the merging tube (55 and 255) runs in a longitudinal direction of the vehicle, Viewed from a front view of the saddle seat vehicle in an upright state, an outer surface (74) of the merging tube (55 and 255) is an inclined surface which is inclined outwards and upwards in the direction of the width of the vehicle, the merging pipe (55 and 255) is provided with the one exhaust gas sensor (59), viewed in an axial direction of the merging pipe (55 and 255), the merging pipe (55 and 255) has a first surface (71) that connects two adjacent exhaust pipes (51 and 54), and a second surface (72 and 272) that is opposite the first surface (71), and where the exhaust gas sensor (59) is attached to the first surface (71), a curved area (80b and 81b) which bends towards the exhaust gas sensor (59) is positioned at an end area on a downstream side of the exhaust pipe (52 and 53) on the side of the second surface (72 and 272).

Description

[0001] The present invention relates to a saddle seat vehicle.

[0002] Conventionally, a technique is known for detecting exhaust air with an exhaust gas sensor by disposing the exhaust gas sensor on a pipe where exhaust air from a plurality of exhaust pipes is collected (see, for example, JP 2003-83061 A). In JP 2003-83061 A, the detection accuracy with the exhaust gas sensor is improved by straightening the flow of exhaust gas from the plurality of exhaust pipes with a straightening rib and ensuring uniformity of the exhaust air that comes into contact with the exhaust gas sensor.

[0003] JP 2012-97616 A discloses an exhaust device for a saddle-seat vehicle, comprising first and second exhaust pipes and a connecting portion. The connecting portion includes first and second connecting ports and a flow straightening member. The connecting portion is formed by welding a plurality of plate members.

[0004] In a saddle-seat vehicle, mounting space for components is limited, and a vehicle body is inclined transversely. Accordingly, when a conventional exhaust gas sensor is mounted on a saddle-seat vehicle, it is preferable to arrange the exhaust gas sensor and an exhaust pipe in a compact manner and to ensure a stable transverse inclination angle of the vehicle body. Furthermore, even in a structure in which the exhaust gas sensor and the exhaust pipe are arranged compactly, it is preferable that the exhaust gas can be detected with high accuracy using a small number of exhaust gas sensors.

[0005] The present invention has been achieved in view of the above-mentioned circumstances, and an object thereof is to provide a saddle-seat vehicle in which an exhaust gas sensor and an exhaust pipe are arranged in a compact manner while ensuring a bank angle, and the exhaust air can be detected with high accuracy using a small number of exhaust gas sensors.

[0006] A saddle-seat vehicle includes an engine (11), a plurality of exhaust pipes (51, 52, 53, and 54) connected to the engine (11), a merging portion (60 and 260) at which the plurality of exhaust pipes (51, 52, 53, and 54) are merged, and an exhaust gas sensor (59). In the saddle-seat vehicle, the merging portion (60 and 260) is arranged offset outward in a vehicle width direction with respect to a center of the vehicle width. The respective exhaust pipes (51, 52, 53, and 54) are arranged with at least three of the pipes in a bundle so as to be in contact with at least the two adjacent exhaust pipes in the merging portion (60 and 260). A merging pipe (55 and 255) covering an entire circumference of the merging portion (60 and 260) is arranged. The merging pipe (55 and 255) runs in a longitudinal direction of the vehicle.When viewed in a front view of the saddle-seat vehicle in an upright state, an outer surface (74) of the merging pipe (55 and 255) is an inclined surface that is inclined outward and upward in the vehicle width direction. The merging pipe (55 and 255) is provided with an exhaust gas sensor (59). When viewed in an axial direction of the merging pipe (55 and 255), the merging pipe (55 and 255) has a first surface (71) connecting two adjacent exhaust pipes (51 and 54) and a second surface (72 and 272) opposite to the first surface (71). The exhaust gas sensor (59) is attached to the first surface (71). A bent portion (80b and 81b) which bends toward the exhaust gas sensor (59) is arranged at an end portion on a downstream side of the exhaust pipe (52 and 53) positioned on the side of the second surface (72 and 272).

[0007] Furthermore, in the configuration described above, the bent portion (80b and 81b) may be a portion in which a pipe (80 and 81) has circular cross-sectional area bends.

[0008] Furthermore, the above-described configuration may be configured as follows. The plurality of exhaust pipes (51, 52, 53, and 54) are arranged with four of the pipes in a bundle, so that an outer shape of the junction pipe (55) becomes approximately a parallelogram when viewed in the axial direction of the junction pipe (55). A bottom portion (72) of the junction pipe (55) is arranged approximately parallel to the floor (G).

[0009] Furthermore, the above-described configuration can be configured as follows. The exhaust pipes (51, 52, 53, and 54) are four pipes bundled into pipes (51c, 52c, 53c, and 54c), each having a polygonal cross-sectional area in the junction region (60). Each of the two polygonal pipes (51c, 52c, 53c, and 54c), positioned diagonally adjacent to each other, has an identical cross-sectional shape.

[0010] Furthermore, the above-described configuration may be configured as follows. The exhaust pipes (51, 52, 53, and 54), a plurality of which are bundled, are pipes (51c, 52c, 53c, and 54c) having respective polygonal cross-sectional areas in the merging portion (60 and 260). The exhaust pipe (52 and 53) positioned on the second surface (72 and 272) side is provided with a circular pipe (80 and 81) extending from the polygonal pipes (52c and 53c) into the merging pipe (55 and 255). The bent portion (80b and 81b) is disposed in the circular pipe (80 and 81).

[0011] Furthermore, the above-described configuration can be configured as follows. The first surface (71) is an upper surface portion of the merging pipe (55 and 255). The second surface (72 and 272) is a lower side portion of the merging pipe (55 and 255). The exhaust pipes (51, 52, 53, and 54) include a pair of upper exhaust pipes (51 and 54) arranged side by side on the left and right in the merging portion (60 and 260), and a lower exhaust pipe (52 and 53) arranged below the upper exhaust pipes (51 and 54) in the merging portion (60 and 260). The circular pipe (80 and 81) is arranged in the lower exhaust pipe (52 and 53).

[0012] Furthermore, in the configuration described above, the first surface (71) may be an upper surface portion of the merging tube (55 and 255).

[0013] Furthermore, the above-described configuration may be configured as follows. The converging pipe (55 and 255) has a narrowed portion (75) in which a diameter is narrowed. The exhaust gas sensor (59) is arranged at the narrowed portion (75) or at a downstream side of the narrowed portion (75) in a flow of exhaust air. A body frame (10) overlaps the exhaust gas sensor (59) from an outer side in the vehicle width direction.

[0014] Furthermore, the above-described configuration may be configured as follows. A catalyst device (56) is arranged at a rear side of the converging pipe (55 and 255). The exhaust gas sensor (59) is positioned below the engine (11) and between a crankshaft (30) of the engine (11) and a clutch shaft (34), as viewed from a side view of the vehicle.

[0015] Furthermore, the above-described configuration may be configured as follows. An oil pan (83) is arranged at a lower portion of the engine (11). The oil pan (83) has a pair of left and right recessed portions (83c) that open downward and toward outer lateral sides as viewed from a front view of the vehicle. The merging pipe (55 and 255) is arranged at one of the recessed portions (83c).

[0016] Furthermore, in the design described above, the merging pipe (55 and 255) can be provided with only one exhaust gas sensor (59).

[0017] Furthermore, in the configuration described above, the exhaust gas sensor (59) may be arranged at an end portion on a downstream side of the merging pipe (55 and 255).

[0018] A saddle-seat vehicle includes an engine, a plurality of exhaust pipes connected to the engine, a merging portion where the plurality of exhaust pipes are merged, and an exhaust gas sensor. The merging portion is offset outward in a vehicle width direction from a vehicle width center. The respective exhaust pipes are arranged with at least three of the pipes in a bundle so as to contact at least the two adjacent exhaust pipes in the merging portion. A merging pipe covering an entire circumference of the merging portion is arranged. The merging pipe extends in a vehicle longitudinal direction. In a front view of the saddle-seat vehicle in an upright state, an outer surface of the merging pipe is an inclined surface inclined outward and upward in the vehicle width direction. The merging pipe is provided with an exhaust gas sensor.Viewed in an axial direction of the junction pipe, the junction pipe has a first surface connecting two adjacent exhaust pipes and a second surface opposite the first surface. The exhaust gas sensor is mounted on the first surface. A bent portion, which bends toward the exhaust gas sensor, is arranged at an end portion on a downstream side of the exhaust pipe, positioned on the side of the second surface.

[0019] In this configuration, in the merging portion, the plurality of exhaust pipes are arranged with at least three of the pipes in a bundle such that the respective exhaust pipes are in contact with at least the two adjacent exhaust pipes, and an exhaust gas sensor is arranged. Accordingly, the exhaust pipes and the exhaust gas sensor can be arranged in a compact manner. Moreover, since the outer surface of the merging pipe is the inclined surface inclined outward and upward in the vehicle width direction, a clearance can be ensured between the merging pipe and a ground when the saddle-seat vehicle rolls sideways, and a large roll angle of the saddle-seat vehicle can be ensured. Furthermore, since the exhaust gas sensor is arranged on the first surface of the merging pipe, the exhaust pipe among the two exhaust pipes on the first side surface can be detected with high accuracy by the exhaust gas sensor.Furthermore, exhaust air from the exhaust pipe positioned on the second surface side can be guided through the bent portion of the exhaust pipe to be forwarded toward the exhaust gas sensor. Therefore, even if an exhaust gas sensor is arranged on the merging pipe, the exhaust air can be detected with high accuracy.

[0020] Furthermore, in the design described above, the bent region may be a region where a pipe with a circular cross-sectional area bends.

[0021] In this design, a circular tube, which is relatively easily deformed, is bent to easily form the bent area.

[0022] Furthermore, the above-described configuration can be configured as follows: The plurality of exhaust pipes are arranged with four of the pipes in a bundle, so that an outer shape of the junction pipe becomes approximately a parallelogram when viewed in the axial direction of the junction pipe. A lower surface area of ​​the junction pipe is arranged approximately parallel to the ground.

[0023] With this design, the exhaust pipes can be arranged in a bundle in a compact manner and a large distance between the lower surface area of ​​the merging pipe and the ground can be ensured.

[0024] In addition, the design described above can be configured as follows: The exhaust pipes, as four pipes to be bundled, are pipes that have corresponding polygonal cross-sectional areas in the junction area. Each of the two polygonal pipes, positioned diagonally next to each other, has an identical cross-sectional shape.

[0025] With this design, since the exhaust pipes are polygonal, the exhaust pipes can be tightly bundled and arranged in a compact manner. Furthermore, since the diagonally positioned pipes have an identical cross-sectional shape, the pipes can be formed simply.

[0026] Furthermore, the above-described configuration may be configured as follows. The exhaust pipes, a plurality of which are bundled, are pipes having respective polygonal cross-sectional surfaces in the converging portion. The exhaust pipe positioned on the second surface side is provided with a circular pipe extending from the polygonal pipes into the converging pipe. The bent portion is arranged in the circular pipe.

[0027] Since the exhaust pipes are polygonal in the junction area in this design, the exhaust pipes can be tightly bundled and arranged in a compact manner. Furthermore, even if the junction area is formed by polygonal pipes, the bent portion can be easily formed on the circular pipe extending from the polygonal pipe into the junction pipe.

[0028] Furthermore, the above-described configuration can be configured as follows. The first surface is an upper surface portion of the merging pipe. The second surface is a lower surface portion of the merging pipe. The exhaust pipes include a pair of upper exhaust pipes arranged side by side on the left and right sides in the merging portion, and a lower exhaust pipe arranged below the upper exhaust pipes in the merging portion. The circular pipe is arranged in the lower exhaust pipe.

[0029] With this design, since the first surface to which the exhaust gas sensor is mounted is the upper surface of the converging pipe, the converging pipe can protect the exhaust gas sensor from below. Furthermore, since the circular pipe is located in the lower exhaust pipe, the center of gravity can be lowered.

[0030] Furthermore, in the configuration described above, the first surface may be an upper surface region of the merging pipe.

[0031] In this design, since the first surface to which the exhaust gas sensor is attached is the upper surface area of ​​the merging pipe, the merging pipe can protect the exhaust gas sensor from below.

[0032] Furthermore, the above-described configuration may be configured as follows. The converging pipe has a constricted portion in which a diameter is constricted. The exhaust gas sensor is arranged at the constricted portion or at a downstream side of the constricted portion in a flow of exhaust air. A body frame overlaps the exhaust gas sensor from an outer side in the vehicle width direction.

[0033] With this design, the exhaust air for the exhaust sensor can be collected through the constricted area, and the exhaust air can be detected by the exhaust sensor with high accuracy. Furthermore, the body frame can protect the exhaust sensor from the outside in the vehicle width direction.

[0034] Furthermore, the above-described configuration may be configured as follows. A catalyst device is arranged at a rear side of the converging pipe. The exhaust gas sensor is positioned below the engine and between a crankshaft of the engine and a clutch shaft, as viewed from a side view of the vehicle.

[0035] With this design, the exhaust gas sensor and the catalyst device can be arranged efficiently.

[0036] Furthermore, the above-described configuration may be configured as follows. An oil pan is arranged at a lower portion of the engine. The oil pan has a pair of left and right recessed portions that open downward and toward the outer lateral sides as viewed from the front of the vehicle. The converging pipe is arranged at one of the recessed portions.

[0037] With this design, the oil pan can be correctly balanced on the left and right sides, and the oil pan's upright position can be improved. Furthermore, the recessed area of ​​the oil pan allows the converging pipe to be arranged in a compact manner.

[0038] Furthermore, in the design described above, the merging pipe can be provided with only one exhaust gas sensor.

[0039] With this design, the exhaust air can be detected with high accuracy by only one exhaust gas sensor.

[0040] Furthermore, in the configuration described above, the exhaust gas sensor may be arranged at an end portion on a downstream side of the merging pipe.

[0041] With this design, a distance between the bent portion and the exhaust gas sensor can be ensured. Accordingly, the exhaust air is easily guided to the exhaust gas sensor through the bent portion, and the bend of the bent portion can be extended, resulting in good exhaust efficiency. Fig. 1 is a right side view of a motorcycle according to a first embodiment of the present invention. Fig. 2 is a perspective view of an exhaust device viewed from the right side. Fig. 3 is an exploded perspective view of a portion of a merging pipe in the exhaust device. Fig. 4 is a view of a merge area viewed from a downstream side. Fig. 5 is a cross-sectional view taken along the line VV of Fig. 2 was created. Fig. 6 is a cross-sectional view taken along the line VI-VI of Fig. 2 was created. Fig. Figure 7 is a right side view of the merging area and merging tube. Fig. 8 is a view of the merging portion and an exhaust gas sensor in an axial direction of the polygonal tube portions as viewed from the downstream side. Fig. 9 is a view of the merging portion and the exhaust gas sensor in an axial direction of an axis of a circular pipe as viewed from the downstream side. Fig. 10 is a view of the merging portion and the exhaust gas sensor in an axial direction of an axis of the circular pipe as viewed from the downstream side. Fig. 11 is a right side view illustrating a structure of a lower portion of the motorcycle and the peripheral portion thereof. Fig. 12 is a front view of the structure of the lower portion of the engine and the peripheral portion thereof viewed from a front side of the vehicle. Fig. 13 is a cross-sectional view taken along the line XIII-XIII of Fig. 11 was created. Fig. 14 is a view of a merging portion and an exhaust gas sensor in an axial direction of the polygonal tube portions as viewed from a downstream side according to a second embodiment.

[0042] Embodiments of the present invention will be described below with reference to the drawings. In the description, descriptions of directions such as front and rear, left and right, and up and down are identical to directions with respect to a vehicle body unless specifically stated. Reference character FR shown in each drawing indicates a front side of the vehicle body, reference character UP indicates an upper side of the vehicle body, and reference character LH indicates a left side of the vehicle body.

[0043] Fig. 1 is a right side view of a motorcycle 1 according to a first embodiment of the present invention.

[0044] The motorcycle 1 is a vehicle in which an engine 11 as a power unit is supported by a vehicle body frame 10, a front fork 12 is steerably supported by a front end of the body frame 10, and a swing arm 13 is disposed at a rear portion of the vehicle body frame 10. The front fork 12 steerably supports a front wheel 2. The swing arm 13 supports a rear wheel 3 (wheel).

[0045] The motorcycle 1 is a saddle-seat vehicle having a seat 14 on which a rider sits astride. The seat 14 is arranged at a rear portion of the vehicle body frame 10.

[0046] The vehicle body frame 10 includes a head tube 15, a pair of left and right main frames 16, a pair of left and right down frames 17, and a pair of left and right lower frames 18. The head tube 15 is disposed at the front end of the vehicle body frame 10. The pair of left and right main frames 16 extend rearward and downward from the head tube 15. The pair of left and right down main frames 17 extend downward from the head tube 15. The pair of left and right lower frames 18 extend rearward from rear ends of the down frames 17 and are connected to the lower end portions of the main frames 16.

[0047] The vehicle body frame 10 also includes a pair of left and right seat frames 19 extending rearward from the main frames 16. The main frames 16 have lower end portions at which pivot portions 20 supporting the swing arm 13 are disposed.

[0048] In detail, lower end portions of the downward frames 17 bend rearward and extend rearward. The lower frames 18 have front end portions combined with rear end portions of the downward frames 17 by welding portions 18a provided at these front end portions. The lower frames 18 have rearward extending portions 18b and upward extending portions 18c. The rearward extending portions 18b extend rearward passing under the engine 11. The upward extending portions 18c extend rearward and upward from rear ends of the rearward extending portions 18b and are connected to the seat frames 19. The main frames 16 have lower ends connected to intermediate portions in a vertical direction of the upward extending portions 18c.

[0049] The front fork 12 is rotatably supported by the body frame 10 via a steering shaft (not shown) inserted into the head pipe 15. The front fork 12 has an upper end portion on which a steering handlebar 22 is disposed. The front wheel 2 is rotatably supported by an axle 2a mounted on a lower end portion of the front fork 12.

[0050] The swing arm 13 is pivotally supported by a pivot shaft 23, which is supported by left and right pivot sections 20. The pivot shaft 23 extends horizontally in a vehicle width direction. The swing arm 13 has a front end portion pivotally supported by the pivot shaft 23 and swings vertically centrally on the pivot shaft 23.

[0051] The rear wheel 3 is rotatably supported by an axle 3a which is held at a rear end portion of the swing arm 13.

[0052] The motorcycle 1 has a rear suspension 24 which bridges between the rear end region of the swing arm 13 and the seat frame 19.

[0053] The engine 11 is arranged on the rear sides of the downwardly extending frames 17 and between the main frames 16 and the lower frames 18 and is fastened to the body frame 10.

[0054] The engine 11 includes a crankcase 31 and a cylinder portion 32. The crankcase 31 supports a crankshaft 30 extending horizontally in the vehicle width direction (left and right directions). The cylinder portion 32 extends upward from a top surface of a front portion of the crankcase 31. The cylinder portion 32 includes a cylinder 32a, a cylinder head 32b, and a cylinder head cover 32c in this order from the crankcase 31 side.

[0055] A piston 32d, which reciprocates in the cylinder 32a, is connected to the crankshaft 30 via a connecting rod (not shown).

[0056] A cylinder axis 32e of the cylinder 32a is inclined forward with respect to a vertical direction.

[0057] The engine 11 is a multi-cylinder in-line engine in which a plurality of cylinders, in which pistons 32d are arranged, are arranged side by side in an axial direction (vehicle width direction) of the crankshaft 30. In this first embodiment, an engine 11 is a four-cylinder in-line engine, and four cylinders are arranged side by side in the axial direction of the crankshaft 30.

[0058] Overall, the engine 11 has a first cylinder, a second cylinder, a third cylinder, and a fourth cylinder in the order from one side (left side of the vehicle) in the vehicle width direction. Fig. 1 shows an outer surface of the fourth cylinder.

[0059] The crankcase 31 has a rear portion which is a gear case portion 31a which accommodates a gear (not shown).

[0060] The transmission housing portion 31a is provided with a clutch device 33 that switches the connection and connection of the rotation of the transmission between the crankshaft 30 and the above-described transmission. The clutch device 33 is a friction clutch device and is held by a clutch shaft 34 disposed in the transmission housing portion 31a. The clutch shaft 34 is arranged parallel to the crankshaft 30 at a rear side of the crankshaft 30.

[0061] The output from the engine 11 is transmitted to the rear wheel 3 via a drive chain 35 which connects an output shaft of the transmission described above to the rear wheel 3.

[0062] The engine 11 has an exhaust device 36 connected to exhaust ports on a front side of the cylinder head 32b.

[0063] The engine 11 has an intake device 37 connected to intake ports at a rear side of the cylinder head 32b.

[0064] A fuel tank 38 is arranged on the upper sides of the main frame 16 and between the head pipe 15 and the seat 14. The seat 14 is arranged on the upper sides of the seat frames 19.

[0065] The motorcycle 1 has a front fairing 39 and side fairings 40. The front fairing 39 covers an upper portion of the front fork 12 and the head pipe 15 from the front and the left and right sides. The side fairings 40 cover a lower side portion of the seat 14 from the sides.

[0066] The front fork 12 holds a front fender 41.

[0067] The left and right pivoting portions 20 have rear sides on which a pair of left and right footsteps 42 are arranged, on which feet of a driver of the seat 14 are placed.

[0068] The motorcycle 1 has lateral sides at the rear portion to which a pair of left and right luggage cases 43 are attached.

[0069] Fig. 2 is a perspective view of the exhaust device 36 viewed from a right side.

[0070] With reference to Fig. 1 and Fig. 2, the exhaust device 36 includes a first exhaust pipe 51 (exhaust pipe, two adjacent exhaust pipes), a second exhaust pipe 52 (exhaust pipe, exhaust pipe positioned on a second surface side), a third exhaust pipe 53 (exhaust pipe, exhaust pipe positioned on a second surface side), and a fourth exhaust pipe 54 (exhaust pipe, two adjacent exhaust pipes). The first exhaust pipe 51 is connected to an exhaust port of the above-described first cylinder in the cylinder head 32b. The second exhaust pipe 52 is connected to an exhaust port of the above-described second cylinder in the cylinder head 32b. The third exhaust pipe 53 is connected to an exhaust port of the above-described third cylinder in the cylinder head 32b. The fourth exhaust pipe 54 is connected to an exhaust port of the above-described fourth cylinder in the cylinder head 32b.

[0071] The exhaust device 36 also includes a merging pipe 55, a catalyst device 56, a connecting pipe 57 and a muffler 58 ( Fig. 1). The converging pipe 55 is connected to end portions on a downstream side of the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54. The catalyst device 56 is connected to a downstream end of the converging pipe 55. The connecting pipe 57 extends from a downstream end of the catalyst device 56. The muffler 58 is connected to a downstream end of the connecting pipe 57.

[0072] In addition, the exhaust device 36 has an exhaust sensor 59 that detects exhaust air flowing in the exhaust device 36.

[0073] The exhaust air flowing in the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53 and the fourth exhaust pipe 54 flows in order through the merging pipe 55, the catalyst device 56, the connecting pipe 57 and the muffler 58 and is discharged to the outside from the muffler 58.

[0074] The first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 have engine connection portions 51a, 52a, 53a, and 54a at upstream ends, which are connected to the respective exhaust ports of the cylinder head 32b. That is, the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 are arranged side by side in the vehicle width direction in an order from one side (left side) in the vehicle width direction.

[0075] The first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 have downwardly extending portions 51b, 52b, 53b, and 54b that extend in front of the engine 11 from the engine connection portions 51a, 52a, 53a, and 54a and extend downwardly. The downwardly extending portions 51b, 52b, 53b, and 54b have lower end portions that bend rearward and are positioned on a lower side of the front portion of the crankcase 31.

[0076] Fig. 3 is an exploded perspective view of a portion of the merge tube 55 in the exhaust device 36.

[0077] In the downward portions 51b, 52b, 53b, and 54b, polygonal tube portions 51c, 52c, 53c, and 54c (polygonal tubes) having polygonal cross-sectional areas are respectively arranged at end portions on a downstream side in an exhaust air flow.

[0078] The exhaust device 36 has a merging portion 60 where the polygonal tube portions 51c, 52c, 53c, and 54c are bundled together. The merging portion 60 is positioned at the lower side of the front portion of the crankcase 31 and extends in a vehicle longitudinal direction.

[0079] Fig. 4 is a view of the merging area 60 viewed from a downstream side (rear side). Fig. 4, a circular tube 80 and a circular tube 81, which will be described below, are not shown.

[0080] The polygonal tube portion 51c of the first exhaust pipe 51 is a tube having a pentagonal cross-sectional area. Specifically, the polygonal tube portion 51c is formed by radially expanding the end portion of the downwardly extending portion 51b to form a pentagonal portion and fitting an outer tube 51d having a pentagonal cross-sectional area on an outer periphery of the pentagonal portion. The first exhaust pipe 51 is the tube having a circular cross-sectional area on an upstream side relative to the polygonal tube portion 51c.

[0081] The polygonal tube portion 52c of the second exhaust pipe 52 is a tube having a quadrangular cross-sectional area. The polygonal tube portion 52c is formed by radially expanding the end portion of the downwardly extending portion 52b to form a quadrangular portion and fitting an outer tube 52d having a quadrangular cross-sectional area on an outer periphery of the quadrangular portion. The second exhaust pipe 52 is the tube having a circular cross-sectional area on an upstream side relative to the polygonal tube portion 52c.

[0082] The polygonal tube portion 53c of the third exhaust pipe 53 is a tube having a pentagonal cross-sectional area. The polygonal tube portion 53c is formed by radially expanding the end portion of the downwardly extending portion 53b to form a pentagonal portion and fitting an outer tube 53d having a pentagonal cross-sectional area on an outer periphery of the pentagonal portion. The third exhaust pipe 53 is the tube having a circular cross-sectional area on an upstream side relative to the polygonal tube portion 53c.

[0083] The polygonal tube portion 54c of the fourth exhaust pipe 54 is a tube having a quadrangular cross-sectional area. The polygonal tube portion 54c is formed by radially expanding the end portion of the downwardly extending portion 54b to form a quadrangular portion and fitting an outer tube 54d having a quadrangular cross-sectional area to an outer periphery of the quadrangular portion. The fourth exhaust pipe 54 is the tube having a circular cross-sectional area on an upstream side relative to the polygonal tube portion 54c.

[0084] In detail, as in the Fig. 4, the polygonal tube portion 51c of the first exhaust pipe 51 includes a lower surface 61a, a pair of side surfaces 61b and 61c, and a pair of upper surfaces 61d and 61e. The pair of side surfaces 61b and 61c are arranged upright from both ends of the lower surface 61a. The pair of upper surfaces 61d and 61e extend from ends of the side surfaces 61b and 61c so as to approach each other to intersect at an apex portion 61f. Thus, the polygonal tube portion 51c of the first exhaust pipe 51 is formed into a pentagon.

[0085] The apex region 61f is a vertex opposite the lower surface 61a. The side surfaces 61b and 61c increase a mutual distance as they approach the side of the apex region 61f from the lower surface 61a.

[0086] The polygonal tube portion 51c is the symmetrical pentagon centered on a center line 61g of a bisector of the lower surface 61a.

[0087] The polygonal pipe portion 53c of the third exhaust pipe 53 has the same shape as the polygonal pipe portion 51c and has a lower surface 63a, a pair of side surfaces 63b and 63c, and a pair of upper surfaces 63d and 63e intersecting at the apex portion 63f, thereby being formed into a pentagon.

[0088] The polygonal tube portion 51c and the polygonal tube portion 53c are arranged such that the lower surface 61a and the lower surface 63a abut each other. The polygonal tube portion 51c and the polygonal tube portion 53c are arranged symmetrically centrally along an axis of symmetry 65 that passes through a contact surface between the lower surface 61a and the lower surface 63a and runs parallel to the contact surface. The axis of symmetry 65 is perpendicular to the center line 61g.

[0089] The center line 61g of the polygonal tube area 51c corresponds to a center line 63g of the polygonal tube area 53c.

[0090] The side surface 61b and the side surface 63b are surfaces in the vehicle width direction. The side surfaces 61c and 63c are outer surfaces in the vehicle width direction.

[0091] The polygonal tube portion 52c of the second exhaust pipe 52 has a lower surface 62a, a lower surface 62b, an upper surface 62c, and an upper surface 62d. The lower surface 62a abuts the side surface 61b. The lower surface 62b abuts the side surface 63b. The upper surface 62c is opposite the lower surface 62a. The upper surface 62d is opposite the lower surface 62b. Thus, the polygonal tube portion 52c of the second exhaust pipe 52 is formed as a quadrilateral.

[0092] The polygonal tube portion 52c is the quadrilateral having a symmetrical shape centered on the symmetry axis 65. A vertex portion 62e, where the lower surface 62a and the lower surface 62b intersect, and a vertex portion 62f, where the upper surface 62c and the upper surface 62d intersect, are positioned on the symmetry axis 65.

[0093] The polygonal tube portion 54c of the fourth exhaust pipe 54 has a shape identical to the polygonal tube portion 52c of the second exhaust pipe 52. The polygonal tube portion 54c and the polygonal tube portion 52c are arranged symmetrically at the center of the center line 61g.

[0094] The polygonal tube portion 54c of the fourth exhaust pipe 54 has a lower surface 64a, a lower surface 64b, an upper surface 64c, and an upper surface 64d. The lower surface 64a abuts the side surface 61c. The lower surface 64b abuts the side surface 63c. The upper surface 64c is opposite the lower surface 64a. The upper surface 64d is opposite the lower surface 64b. Thus, the polygonal tube portion 54c of the first exhaust pipe 54 is formed into a quadrilateral.

[0095] The polygonal tube portion 54c is the quadrilateral having a symmetrical shape centered on the symmetry axis 65. A vertex portion 64e, where the lower surface 64a and the upper surface 64b intersect, and a vertex portion 64f, where the upper surface 64c and the upper surface 64d intersect, are positioned on the symmetry axis 65.

[0096] The merging portion 60 is a portion where the four of the polygonal tube portion 51c, the polygonal tube portion 52c, the polygonal tube portion 53c, and the polygonal tube portion 54c are arranged in a bundle, so that an external shape of the merging portion 60 becomes a parallelogram when viewed in an axial direction of the merging portion 60.

[0097] In detail, the polygonal tube portion 51c and the polygonal tube portion 54c are arranged side by side on the left and right in a state where they abut against each other.

[0098] The polygonal tube portion 52c and the polygonal tube portion 53c are arranged in a state of abutting against each other below the polygonal tube portion 51c and the polygonal tube portion 54c.

[0099] The polygonal tube portion 51c and the polygonal tube portion 54c are upper exhaust pipes arranged above the polygonal tube portion 52c and the polygonal tube portion 53c. The polygonal tube portion 52c and the polygonal tube portion 53c are lower exhaust pipes arranged below the polygonal tube portion 51c and the polygonal tube portion 54c.

[0100] An outer peripheral surface 66 of the merging portion 60 is defined by the upper surface 61e, the upper surface 64d, the upper surface 64c, the upper surface 63e, the upper surface 63d, the upper surface 62c, the upper surface 62d, and the upper surface 61d. An outer shape of this outer peripheral surface 66 is a parallelogram. In detail, the outer shape of the outer peripheral surface 66 is a diamond shape, in which the axis of symmetry 65 and the center line 61g are diagonal lines. If the axis of symmetry 65 and the center line 61g are considered diagonal lines of this diamond shape, the axis of symmetry 65 is the diagonal line longer than the center line 61g. The merging portion 60 is arranged such that the symmetry axis 65 is an oblique line inclined so as to be positioned upward as a head portion in the vehicle width direction.

[0101] Since the outer peripheral surface 66 has the diamond shape, an upper surface 66a and a lower surface 66b of the outer peripheral surface 66 are parallel, and an inner surface 66c and an outer surface 66d of the outer peripheral surface 66 are parallel.

[0102] The upper surface 66a and the lower surface 66b are approximately horizontal and approximately parallel to a floor when viewed in the axial direction of the merging portion 60.

[0103] When viewed in the axial direction of the merging portion 60, the inner surface 66c and the outer surface 66d are inclined surfaces inclined so as to be positioned upward as an outer area in the vehicle width direction.

[0104] In the merging region 60, the polygonal pipe region 51c abuts the three exhaust pipes of the polygonal pipe region 52c, the polygonal pipe region 53c and the polygonal pipe region 54c.

[0105] In the merging region 60, the polygonal pipe region 52c abuts the two exhaust pipes of the polygonal pipe region 51c and the polygonal pipe region 53c.

[0106] In the merging region 60, the polygonal pipe region 53c abuts the three exhaust pipes of the polygonal pipe region 51c, the polygonal pipe region 52c and the polygonal pipe region 54c.

[0107] In the merging region 60, the polygonal pipe region 54c abuts the two exhaust pipes of the polygonal pipe region 51c and the polygonal pipe region 53c.

[0108] That is, in the merging portion 60, respective polygonal pipe portions 51c, 52c, 53c and 54c are arranged with the four pipes in a bundle so as to be in contact with at least two adjacent exhaust pipes.

[0109] Fig. 5 is a cross-sectional view taken along the line VV of Fig. 2 was created. Fig. 6 is a sectional view taken along the line VI-VI of Fig. 2 was created. Fig. 7 is a right side view of the merging area 60 and the merging tube 55. In Fig. 7, a lower half body 69 described below is not shown.

[0110] With reference to Fig. 1 to Fig. 7, the merging pipe 55 is a pipe extending in the vehicle longitudinal direction under the crankcase 31. The merging pipe 55 has an upstream end 55a on a front end side connected to the merging portion 60, and a downstream end 55b on a rear end side connected to the catalyst device 56.

[0111] The merging pipe 55 is formed in a tubular shape combining an upper half body 68 and the lower half body 69. The upper half body 68 and the lower half body 69 have plate shapes and are vertically divided.

[0112] The merging pipe 55 is connected to the merging portion 60 by having an inner peripheral surface of the upstream end 55a fitted to the outer peripheral surface 66 of the merging portion 60.

[0113] The merging tube 55 covers an entire circumference of the outer peripheral surface 66 of the merging portion 60. The merging tube 55 is formed according to the outer peripheral surface 66 of the merging portion 60. Viewed in an axial direction of the merging tube 55, an outer shape of the merging tube 55 is a diamond shape similar to the outer peripheral surface 66.

[0114] In detail, as in Fig. 6, the merging pipe 55 has a first surface 71, a second surface 72, a third surface 73, and a fourth surface 74. As viewed in the axial direction of the merging pipe 55, the first surface 71 connects the polygonal pipe portion 51c and the polygonal pipe portion 54c, which are adjacent to each other, in a left and right direction. The second surface 72 connects the polygonal pipe portion 52c and the polygonal pipe portion 53c, which are adjacent to each other, in the left and right direction. The third surface 73 connects the polygonal pipe portion 51c and the polygonal pipe portion 52c, which are adjacent to each other, in a vertical direction. The fourth surface 74 connects the polygonal pipe portion 54c and the polygonal pipe portion 53c, which are adjacent to each other, in the vertical direction.

[0115] The second surface 72 is a lower surface portion of the diamond-shaped merging tube 55 and is approximately horizontal. Specifically, the second surface 72 is slightly inclined to be positioned downward in the vehicle width direction as a head portion. The second surface 72 covers the lower surface 66b of the outer peripheral surface 66.

[0116] The first surface 71 is an upper surface portion of the diamond-shaped merging tube 55 and parallel to the second surface 72. The first surface 71 covers the upper surface 66a of the outer peripheral surface 66.

[0117] The fourth surface 74 is an outer surface portion of the diamond-shaped merging pipe 55 and is an inclined surface that slopes outward and upward in the vehicle width direction when viewed from a front view of the motorcycle 1 in an upright state. The fourth surface 74 covers the upper surface 66d of the outer peripheral surface 66.

[0118] The third surface 73 is an inner surface portion of the diamond-shaped merging tube 55 and parallel to the fourth surface 74. The third surface 73 covers the inner surface 66c of the outer peripheral surface 66.

[0119] The first surface 71 and the third surface 73 are arranged on the upper half body 68 and the second surface 72 and the fourth surface 74 are arranged on the lower half body 69.

[0120] With reference to Fig. 5 and Fig. 7, the merging tube 55 has a rear portion where a narrowed portion 75 is arranged. The narrowed portion 75 is a region where a diameter of the merging tube 55 is narrowed. An inner diameter of the narrowed portion 75 is smaller than an inner diameter of the upstream end 55a of the merging tube 55 and an inner diameter of the downstream end 55b of the merging tube 55.

[0121] The catalyst device 56 includes an outer tube portion 56a and a catalyst body (not shown) housed in the outer tube portion 56a. The downstream end 55b of the merging tube 55 is fitted to an upstream end of the outer tube portion 56a of the catalyst device 56 to be connected to the catalyst device 56. The downstream end 55b is formed in a circular shape when viewed in an axial direction according to a shape of the outer tube portion 56a.

[0122] The first surface 71 of the merging pipe 55 is provided with a sensor mounting portion 76 to which the exhaust gas sensor 59 is mounted. The sensor mounting portion 56 is a tubular portion that passes through the first surface 71 in the vertical direction.

[0123] With reference to Fig. 5, the exhaust gas sensor 59 has a rod shape and includes a detection portion 59a that detects an oxygen concentration in the exhaust air at a distal end portion. The exhaust gas sensor 59 has a base end portion to which an electric wire 59b is connected. The electric wire 59b transmits a detection result of the detection portion 59a to a control unit (not shown) of the motorcycle 1.

[0124] The exhaust gas sensor 59 is inserted into the sensor mounting portion 56 from an outside, and the detection portion 59a is arranged in the converging pipe 55. The exhaust gas sensor 59 is arranged to be inclined so that an axis 59c of the exhaust gas sensor 59 is directed outward and upward in the vehicle width direction as viewed in the axial direction of the converging pipe 55.

[0125] The exhaust gas sensor 59 is arranged downstream of the narrowed region 75 on the first surface 71 and at the end region on the downstream side of the merging pipe 55.

[0126] With reference to Fig. 6, the joining portion 60 is integrated by welding with each of the lower surface 61a and the lower surface 63a, the side surface 61b and the lower surface 62a, the side surface 61c and the lower surface 64a, the lower surface 64b and the side surface 63c, and the side surface 63b and the lower surface 62b.

[0127] In addition, the merging tube 55 is welded to the outer peripheral surface 66 of the merging region 60 approximately over an entire circumference of the upstream end 55a.

[0128] The polygonal tube portion 51c and the polygonal tube portion 53c are arranged so that they are positioned diagonally adjacent to each other. The polygonal tube portion 51c and the polygonal tube portion 53c have the same shape and are formed by plastic deformation into an identical pentagonal shape. Therefore, the mold can be used together to simplify the manufacturing of the polygonal tube portion 51c and the polygonal tube portion 53c.

[0129] The polygonal tube portion 52c and the polygonal tube portion 54c are arranged so that they are positioned diagonally adjacent to each other. The polygonal tube portion 52c and the polygonal tube portion 54c have the same shape and are formed into an identical quadrilateral shape by plastic deformation. Therefore, the mold can be used together to simplify the manufacturing of the polygonal tube portion 52c and the polygonal tube portion 54c.

[0130] Fig. Fig. 8 is a view of the merging portion 60 and the exhaust gas sensor 59 in the axial direction of the polygonal tube portion 51c and the polygonal tube portion 54c viewed from the downstream side. Fig. 8, the merging pipe 55 is shown as a virtual line.

[0131] With reference to Fig. 3 and Fig. 5 to Fig. 8, in the junction region 60, the polygonal tube region 52c and the polygonal tube region 53c, positioned on the second surface 72 side, are provided with circular tubes 80 and 81, respectively. The circular tubes 80 and 81 extend to a downstream side toward an inside of the junction tube 55. The circular tubes 80 and 81 have circular cross-sectional areas.

[0132] The circular tube 80 is inserted into the polygonal tube portion 52c from the downstream side, fitted to an inner peripheral portion of the portion on the upstream side with respect to the polygonal tube portion 52c in the downward portion 52b, and fixed to the downward portion 52b by welding.

[0133] With reference to Fig. 7 and Fig. 8, the circular tube 80 is positioned in the vehicle width direction and on a lower side with respect to the detection area 59a of the exhaust gas sensor 59. The circular tube 80 is also positioned on the upstream side with respect to the detection area 59a.

[0134] The circular tube 80 has a bent portion 80b that is bent such that an opening 80a at a downstream end of the circular tube 80 faces the detection portion 59a. That is, the bent portion 80b bends the circular tube 80 outward and upward in the vehicle width direction.

[0135] As in Fig. 7, an axis 80c of the circular tube 80 extending from the opening 80a to the downstream side overlaps the detection area 59a.

[0136] The circular tube 81 is inserted into the polygonal tube portion 53c from the downstream side, fitted to an inner peripheral portion of the portion on the upstream side with respect to the polygonal tube portion 53c in the downward portion 53b, and fixed to the downward portion 53b by welding.

[0137] With reference to Fig. 7 and Fig. 8, the circular tube 81 is positioned on the upstream side and a lower side with respect to the detection area 59a of the exhaust gas sensor 59.

[0138] The circular tube 81 has a bent portion 81b that is bent such that an opening 81a at a downstream end of the circular tube 81 faces the detection portion 59a. That is, the bent portion 81b bends the circular tube 81 upward.

[0139] As in Fig. 7, an axis 81c of the circular tube 81 extending from the opening 81a to the downstream side overlaps the detection area 59a.

[0140] As in Fig. 8, when the merging portion 60 and the exhaust gas sensor 59 are viewed from the downstream side in the axial direction of the polygonal tube portion 51c and the polygonal tube portion 54c, the detection portion 59a overlaps an opening 51e at a downstream end of the polygonal tube portion 51c and an opening 54e at a downstream end of the polygonal tube portion 54c.

[0141] This causes exhaust air flowing from the polygonal pipe section 51c to the merging pipe 55 and exhaust air flowing from the polygonal pipe section 54c to the merging pipe section 55 to directly contact the detection section 59a. Therefore, exhaust air from the first exhaust pipe 51 and the fourth exhaust pipe 54 can be detected by the exhaust sensor 59 with high accuracy.

[0142] Furthermore, when the exhaust gas sensor 59 is viewed from the downstream side in the axial direction of the polygonal tube portion 51c and the polygonal tube portion 54c, the detection area 59a is positioned on an upper side with respect to the polygonal tube portion 52c and the polygonal tube portion 53c, and does not overlap the polygonal tube portion 52c or the polygonal tube portion 53c. Therefore, it is not necessary to extend the detection area 59a in any special way, and a general exhaust gas sensor 59 can be used.

[0143] Fig. 9 is a view of the merging portion 60 and the exhaust gas sensor 59 in an axial direction of the axis 80c of the circular pipe 80 as viewed from the downstream side.

[0144] As in Fig. 9, the detection area 59a overlaps the opening 80a of the circular tube 80 in the polygonal tube area 52c in the axial direction of the axis 80c of the circular tube 80.

[0145] This causes air flowing from the polygonal pipe portion 52c through the circular pipe 80 to the merging pipe 55 to directly contact the detection portion 59a. Therefore, exhaust air from the second exhaust pipe 52 can be detected by the exhaust sensor 59 with high accuracy.

[0146] Fig. 10 is a view of the merging portion 60 and the exhaust gas sensor 59 in an axial direction of the axis 81c of the circular pipe 81 viewed from the downstream side.

[0147] As in Fig. 10, the detection area 59a overlaps the opening 81a of the circular tube 81 in the polygonal tube area 53c when viewed in the axial direction of the axis 81c of the circular tube 81.

[0148] This causes exhaust air flowing from the polygonal pipe portion 53c through the circular pipe 81 to the merging pipe 55 to directly contact the detection portion 59a. Therefore, the third exhaust pipe 53 can be detected by the exhaust sensor 59 with high accuracy.

[0149] That is, in this first embodiment, the exhaust air from the first exhaust pipe 51, the exhaust air from the second exhaust pipe 52, the exhaust air from the third exhaust pipe 53, and the exhaust air from the fourth exhaust pipe 54 directly contact the detection area 59a. Therefore, the exhaust air can be detected with high accuracy by the exhaust sensor 59.

[0150] The exhaust air flowing from the merging portion 60 to the merging pipe 55 passes through the constricted portion 75 to become a converged stream, and then contacts the exhaust gas sensor 59 downstream of the constricted portion 75. Therefore, the exhaust air can be efficiently brought into contact with the exhaust gas sensor 59, and the exhaust gas can be detected by the exhaust gas sensor 59 with high accuracy.

[0151] Furthermore, the circular tube 80 and the circular tube 81 have circular cross-sectional areas, and thus, compared to, for example, a tube having a polygonal cross-sectional area, they are easily processed by bending. Therefore, the bent portion 80b and the bent portion 81b can be easily formed.

[0152] As in Fig. 8, the polygonal tube portion 51c and the polygonal tube portion 54c abut each other by a contact surface 86 between the side surface 61c and the lower surface 64a.

[0153] The polygonal tube portion 52c and the polygonal tube portion 53c abut each other by a contact surface 87 between the lower surface 62b and the side surface 63b.

[0154] The abutment surface 86 and the abutment surface 87 are parallel to each other. The abutment surface 86 and the abutment surface 87 extend vertically in the axial direction of the merging tube 55 and are arranged in a direction perpendicular to the first surface 71 of the merging tube 55.

[0155] In addition, the polygonal tube portion 52c and the polygonal tube portion 51c abut each other through an abutment surface 88 between the lower surface 62a and the side surface 61b.

[0156] The polygonal tube portion 53c and the polygonal tube portion 54c abut each other by a contact surface 89 between the lower surface 63c and the lower surface 64b.

[0157] The abutment surface 88 and the abutment surface 89 are parallel to each other and are arranged in a direction perpendicular to the fourth surface 74 of the merging tube 55 as viewed in the axial direction of the merging tube 55.

[0158] Fig. 11 is a right side view illustrating a structure of a lower portion of the engine 11 and the peripheral portion thereof. Fig. 12 is a front view of the structure of the lower portion of the engine 11 and the peripheral portion thereof as viewed from a front side of the vehicle. Fig. 13 is a cross-sectional view taken along the line XIII-XIII of Fig. 11 was created.

[0159] With reference to Fig. 11 to Fig. 13, the engine 11 has an oil pan 83 mounted on a bottom side 31b of the crankcase 31. The oil pan 83 collects oil from the engine 11.

[0160] The oil pan 83 is arranged in a center region in the vehicle width direction and overlaps a center line C in the vehicle width direction of the motorcycle 1. The center line C is a vertical line passing through a floor region 3b ( Fig. 12) of the rear wheel 3 with respect to the ground G in a state in which the motorcycle 1 is upright.

[0161] The oil pan 83 has attachment portions 83a which are fixed to the underside 31b of the crankcase 31 with bolts and an oil storage portion 83b which curves downward with respect to the attachment portions 83a when viewed from the front.

[0162] The oil storage portion 83b is arranged in the center portion in the vehicle width direction, and fixing portions 83a are arranged on the left and right sides of the oil storage portion 83b, respectively.

[0163] The oil storage portion 83b protrudes downward, and thus, a pair of left and right recess portions 83c are formed on the oil pan 83 at the outer lateral sides of the oil storage portion 83b and the lower sides of the mounting portions 83a. The recess portions 83c open downward and toward the outer lateral sides when viewed from the front of the vehicle.

[0164] The oil pan 83 is formed approximately symmetrically in the center of the center line C. In view of this, an ability of the oil pan 83 to stand upright is good when the oil pan 83 is arranged during work such as maintenance, and work is simplified.

[0165] The merging portion 60 and the merging pipe 55 are positioned outward in the vehicle width direction with respect to the center line C and offset outward in the vehicle width direction with respect to a center of the vehicle width.

[0166] In detail, the merging portion 60, the merging pipe 55, and a front end portion of the catalyst device 56 are arranged on one side of the recessed portions 83c (right side) in the vehicle width direction and overlap the oil storage portion 83b in the vehicle width direction in a side view of the vehicle as viewed from the outside. In addition, the exhaust muffler 58 ( Fig. 1) is arranged on a rear side of the catalyst device 56 and an outer lateral side of the rear wheel 3.

[0167] The merging portion 60 and the merging pipe 55 have upper portions located at the recess portion 83c, and the merging portion 60 and the merging pipe 55 have lower portions positioned at a lower side with respect to a lower surface 83d of the oil storage portion 83b.

[0168] Moreover, the merging pipe 55 is disposed inward in the vehicle width direction with respect to the lower frame 18 on one side (right side) in the vehicle width direction and is disposed between the rearward extending portion 18b of the lower frame 18 and the oil storage portion 83b in the vehicle width direction.

[0169] With reference to Fig. 11 and Fig. 13, as viewed from the side view of the vehicle, the rearward extending portion 18b of the lower frame 18 overlaps on one side the upper portion of the merging portion 60 and the exhaust gas sensor 59 in the vehicle width direction from the outside and covers the upper portion of the merging portion 60 and the exhaust gas sensor 59. In view of this, the lower frame 18 can protect the exhaust gas sensor 59 and can improve the appearance in a manner that the exhaust gas sensor 59 is hidden by the lower frame 18.

[0170] Furthermore, the exhaust gas sensor 59 is arranged offset rearward with respect to the welding portion 18a between the downwardly extending frame 17 and the lower frame 18. This prevents the welding portion 18a from interfering with the arrangement of the exhaust gas sensor 59, and a degree of freedom in the arrangement of the exhaust gas sensor 59 is high.

[0171] In addition, since the exhaust gas sensor 59 is arranged on the first surface 71 as the upper surface portion of the merging pipe 55, the merging pipe 55 can protect the exhaust gas sensor 59 from the lower side.

[0172] In addition, the exhaust gas sensor 59 is covered from a top side with the crankcase 31. In view of this, the crankcase 31 can protect the exhaust gas sensor 59 from the top side.

[0173] Furthermore, the circular tube 80 and the circular tube 81 are arranged in the polygonal tube portion 52c and the polygonal tube portion 53c, which are located below the polygonal tube portion 51c and the polygonal tube portion 54c. This can lower the center of gravity of the merging portion 60.

[0174] The crankcase 31 has an outer surface at a lower portion to which a pressure sensor 84 is mounted on an upper side relative to the exhaust gas sensor 59 and the rearward portion 18b of the lower frame 18. The pressure sensor 84 detects an oil pressure in the crankcase 31.

[0175] With reference to Fig. 6 and Fig. 12, the second surface 72 as a lower surface portion of the diamond-shaped merging pipe 55 is approximately parallel to the ground G in a state where the motorcycle 1 stands upright. This can ensure a large distance between the second surface 72 and the ground G, whereby a lowest ground height of the motorcycle 1 can be slightly higher.

[0176] As in Fig. As shown in Figure 12, the footrest 42 has a bank sensor portion 42a projecting downward. The bank sensor portion 42a has a lower end portion, which is a first ground portion 42b that first comes into contact with the ground G when the motorcycle 1 banked left and right.

[0177] The first floor portion 42b is positioned outward in the vehicle direction and at an upper side with respect to the merging pipe 55.

[0178] In Fig. 12, a straight line L1 is shown. The straight line L1 connects the ground area 3b in a center of the rear wheel 3 with the first ground area 42b. In Fig. 12, a straight line L2 is also shown. The straight line L2 connects a lateral end portion 3c of the rear wheel 3 and the first ground portion 42b. The lateral end portion 3c is a ground point between the rear wheel 3 and the ground G when the motorcycle 1 banked left and right. The straight line L1 and the straight line L2 are inclined outward and upward in the vehicle width direction.

[0179] The fourth surface 74, as the outer surface portion of the merging pipe 55, is arranged in the vehicle width direction with respect to the straight line L1 and the straight line L2, and is approximately parallel to the straight line L2. Therefore, when the motorcycle 1 banked in conjunction with a turning operation, a clearance can be ensured between the ground G and the fourth surface 74 of the merging pipe 55, and a large bank angle of the motorcycle 1 can be configured.

[0180] In Fig. 1 and Fig. 11, a vertical line 34a and a vertical line 30a are shown. The vertical line 34a indicates a position in the vehicle width direction of the clutch shaft 34. The vertical line 30a indicates a position in the vehicle length direction of the crankshaft 30.

[0181] The merging pipe 55 and the catalyst device 56 are arranged under the crankcase 31 in a front-to-rear direction, and the catalyst device 56 is positioned at a rear side of the merging pipe 55.

[0182] The exhaust gas sensor 59, which is arranged on a first surface 71 of the merging pipe 55, is positioned below the crankcase 31 and at a front side relative to the clutch shaft 34 and at a rear side of the crankshaft 30. The exhaust gas sensor 59 is positioned between the clutch shaft 34 and the crankshaft 30 in the vehicle longitudinal direction.

[0183] As described above, according to the first embodiment to which the present invention is applied, the motorcycle 1 includes the engine 11, the plurality of the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54, the merging portion 60, and the exhaust gas sensor 59. The plurality of the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 are connected to the engine 11 and merged at the merging portion 60. The merging portion 60 is arranged offset outward in the vehicle width direction with respect to the vehicle width center.The respective exhaust pipes of the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 are arranged with at least three of the pipes in a bundle (four pipes in the first embodiment) so as to be in contact with at least two adjacent exhaust pipes in the converging portion 60. The converging pipe 55 covering the entire circumference of the converging portion 60 is arranged. The converging pipe 55 extends in the vehicle longitudinal direction. In the front view of the motorcycle 1 in an upright state, a fourth surface 74 as the outer surface of the converging pipe 55 is the inclined surface inclined outward and upward in the vehicle width direction. The converging pipe 55 is provided with an exhaust gas sensor 59.Viewed in an axial direction of the merging pipe 55, the merging pipe 55 includes the first surface 71 connecting the two adjacent ones of the first exhaust pipe 51 and the fourth exhaust pipe 54, and the second surface 72 opposite the first surface 71. The exhaust gas sensor 59 is attached to the first surface 71. The bent portion 80b and the bent portion 81b, which bend toward the exhaust gas sensor 59, are positioned at end portions on the downstream side of the second exhaust pipe 52 and the third exhaust pipe 53 on the second surface 72 side.

[0184] With this configuration, in the converging portion 60, at least three of the plurality of the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 are arranged in a bundle such that the respective exhaust pipes contact at least two adjacent exhaust pipes, and the exhaust gas sensor 59 is disposed. Accordingly, the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54, and the exhaust gas sensor 59 can be arranged compactly. Furthermore, since the fourth surface 74 of the converging pipe 55 is the inclined surface inclined outward and upward in the vehicle width direction, a clearance can be ensured between the converging pipe 55 and a ground G when the motorcycle 1 banked, and the large bank angle of the motorcycle 1 can be ensured.Furthermore, since the exhaust gas sensor 59 is disposed on the first surface 71 of the merging pipe 55, the exhaust air from the first exhaust pipe 51 and the fourth exhaust pipe 54, the two pipes on the first surface 71 side, can be detected with high accuracy by the exhaust gas sensor 59. Furthermore, exhaust air from the second exhaust pipe 52 and the third exhaust pipe 53, which are positioned on the second surface 72 side, can be guided through the bent portion 80b and the bent portion 81b to pass toward the exhaust gas sensor 59. In view of this, even if an exhaust gas sensor 59 is disposed on the merging pipe 55, the exhaust air can be detected with high accuracy.

[0185] In addition, the bent portion 80b and the bent portion 81b are portions where the circular tube 80 and the circular tube 81 have bent circular cross-sectional areas.

[0186] In this configuration, a circular tube which is relatively easily deformed is bent to easily form the bent portion 80b and the bent portion 81b.

[0187] Furthermore, the plurality of the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 are arranged in a bundle, so that the outer shape of the merging pipe 55 becomes approximately a parallelogram when viewed in the axial direction of the merging pipe 55. The second surface 72, as the lower surface portion of the merging pipe 55, is arranged approximately parallel to the floor G.

[0188] With this configuration, the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 can be arranged in a bundle in a compact manner, and a large distance between the lower surface portion of the merging pipe 55 and the floor G can be ensured.

[0189] Furthermore, the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54, as the four pipes to be bundled, have the polygonal pipe portion 51c, the polygonal pipe portion 52c, the polygonal pipe portion 53c, and the polygonal pipe portion 54c in the merging portion 60. The polygonal pipe portion 51c, the polygonal pipe portion 52c, the polygonal pipe portion 53c, and the polygonal pipe portion 54c are the pipes each having a polygonal cross-sectional area. The polygonal pipe portion 51c and the polygonal pipe portion 53c, which are positioned diagonally adjacent to each other, have an identical cross-sectional shape. Furthermore, the polygonal pipe portion 52c and the polygonal pipe portion 54c, which are positioned diagonally adjacent to each other, have an identical cross-sectional shape.

[0190] With this configuration, since the polygonal tube portion 51c, the polygonal tube portion 52c, the polygonal tube portion 53c, and the polygonal tube portion 54c are polygonal, the polygonal tube portion 51c, the polygonal tube portion 52c, the polygonal tube portion 53c, and the polygonal tube portion 54c can be densely bundled, and the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 54, and the fourth exhaust pipe 54 can be arranged in a compact manner. Moreover, the polygonal tube portion 51c and the polygonal tube portion 53c have an identical cross-sectional shape, and the polygonal tube portion 52c and the polygonal tube portion 54c have an identical cross-sectional shape. Thus, the polygonal tubes can be easily formed.

[0191] Moreover, the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54, a plurality of which are bundled, are the pipes having respective polygonal cross-sectional areas in the merging portion 60. The second exhaust pipe 52 and the third exhaust pipe 53, positioned on the second side surface 72 side, are provided with the circular pipe 80 and the circular pipe 81 extending from the polygonal pipe portion 52c and the polygonal pipe portion 53c into the merging pipe 55. The bent portion 80b and the bent portion 81b are disposed in the circular pipe 80 and the circular pipe 81.

[0192] With this configuration, since the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 are polygonal in the merging portion 60, the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 can be tightly bundled, and the first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 can be arranged in a compact manner. Moreover, even if the merging portion 60 is formed by polygonal tubes, the bent portion 80b and the bent portion 81b can be easily formed on the circular tube 80 and the circular tube 81 extending from the polygonal tubes into the merging pipe 55.

[0193] Furthermore, the first surface 71 is the upper surface portion of the merging pipe 55. The second surface 72 is the lower surface portion of the merging pipe 55. The first exhaust pipe 51, the second exhaust pipe 52, the third exhaust pipe 53, and the fourth exhaust pipe 54 include the polygonal pipe portion 51c and the polygonal pipe portion 54c as a pair of upper exhaust pipes, and the polygonal pipe portion 52c and the polygonal pipe portion 53c as the lower exhaust pipes. The polygonal pipe portion 51c and the polygonal pipe portion 54c are arranged side by side to the left and right in the merging portion 60. The polygonal pipe portion 52c and the polygonal pipe portion 53c are arranged below the upper exhaust pipes in the merging portion 60. The circular pipe 80 and the circular pipe 81 are arranged at the lower exhaust pipes.

[0194] With this configuration, since the first surface 71 to which the exhaust sensor 59 is mounted is the upper surface of the merging pipe 55, the merging pipe 55 can protect the exhaust sensor 59 from a lower side. Furthermore, since the circular pipe 80 and the circular pipe 81 are arranged in the lower exhaust pipes, a center of gravity can be lowered.

[0195] Furthermore, the junction pipe 55 has the constricted portion 75 where a diameter is narrowed. The reinforcement member 59 is arranged on the downstream side of the constricted connecting portion 75 in the exhaust air flow. The body frame 10 overlaps the exhaust sensor 59 from the outside in the vehicle width direction.

[0196] With this configuration, the exhaust air for the exhaust sensor 59 can be collected through the constricted portion 75, and the exhaust air can be detected with high accuracy by the exhaust sensor 59. Furthermore, the body frame 10 can protect the exhaust sensor 59 from the outside in the vehicle width direction.

[0197] The catalyst device 56 is further arranged at the rear of the converging pipe 55. The exhaust gas sensor 59 is positioned below the engine 11 and between the engine 11 and the crankshaft 30 of the engine 11 and the clutch shaft 34, as viewed from the side of the vehicle.

[0198] With this configuration, the exhaust gas sensor 59 and the catalyst device 56 can be arranged efficiently.

[0199] In addition, the merging pipe 55 is provided with only one exhaust gas sensor 59.

[0200] With this design, the exhaust air can be detected with high accuracy by only one exhaust gas sensor 59.

[0201] In addition, the exhaust gas sensor 59 can be arranged at the end region on a downstream side of the merging pipe 55.

[0202] With this configuration, a distance from the bent portion 80b and the bent portion 81b to the exhaust gas sensor 59 can be ensured. Accordingly, the exhaust air is easily guided to the exhaust gas sensor 59 through the bent portion 80b and the bent portion 81b, and bends of the bent portion 80b and the bent portion 81b can be expanded, resulting in good exhaust efficiency.

[0203] Furthermore, the oil pan 83 is arranged at a lower portion of the engine 11. The oil pan 83 has a pair of left and right recessed portions 83c that open downward and toward the outer lateral sides as viewed from the front of the vehicle. The merging pipe 55 is arranged at one of the recessed portions 83c.

[0204] With this configuration, the oil pan 83 can be properly balanced left and right, and the upright standing ability of the oil pan 83 can be improved. Furthermore, by means of the recessed portion 83c of the oil pan 83, the converging pipe 55 can be arranged in a compact manner.

[0205] In the following, a second embodiment to which the present invention is applied will be described with reference to Fig. 14 is applied. In this second embodiment, identical reference numerals are used for portions similar to the above-described first embodiment, and the description thereof will be omitted.

[0206] While in the above-described first embodiment, it was described that the four of the polygonal tube portion 51c, the polygonal tube portion 52c, the polygonal tube portion 53c, and the polygonal tube portion 54c are arranged in a bundle in the merging portion 60, this second embodiment differs from the above-described first embodiment in that the three of the polygonal tube portion 51c, the polygonal tube portion 53c, and the polygonal tube portion 54c are bundled.

[0207] Fig. 14 is a view in the second embodiment of a merging portion 260 and the exhaust gas sensor 59 in the axial direction of the polygonal tube portion 51c and the polygonal tube portion 54c, viewed from the downstream side. In Fig. 14, a merging pipe 255 is shown as a virtual line.

[0208] In the second embodiment, a three-cylinder in-line engine is mounted in place of the engine 11, and an exhaust device 236 is connected to the engine.

[0209] The exhaust pipe 236 comprises the first exhaust pipe 51, the third exhaust pipe 53, the fourth exhaust pipe 54, a merging pipe 255, the catalyst device 56 ( Fig. 2), the connecting pipe 57 ( Fig. 2) and the exhaust silencer 58 ( Fig. 1). The converging pipe 255 is connected to the downstream end portions of the first exhaust pipe 51, the third exhaust pipe 53, and the fourth exhaust pipe 54. The catalyst device 56 is connected to a downstream end of the converging pipe 255. The connecting pipe 57 extends from a downstream end of the catalyst device 56. The muffler 58 is connected to the downstream end of the connecting pipe 57.

[0210] In addition, the exhaust device 236 has the exhaust sensor 59.

[0211] That is, the exhaust device 236 has a structure that excludes the second exhaust pipe 52 from the exhaust device 36 of the first embodiment described above.

[0212] The first exhaust pipe 51, the third exhaust pipe 53 and the fourth exhaust pipe 54 are bundled in the merging area 260.

[0213] The merging portion 260 is a portion where the three of the polygonal tube portion 51c, the polygonal tube portion 53c, and the polygonal tube portion 54c are arranged in a bundle, so that an outer shape of the merging portion 260 becomes approximately a triangle when viewed in an axial direction of the merging portion 260.

[0214] In detail, the polygonal tube portion 51c and the polygonal tube portion 54c are arranged on the left and right in a state where they abut against each other.

[0215] The polygonal tube portion 53c is disposed below the polygonal tube portion 51c and the polygonal tube portion 54c, and disposed to abut against the polygonal tube portion 51c and the polygonal tube portion 54c.

[0216] The polygonal tube portion 51c and the polygonal tube portion 54c are upper exhaust pipes located above the polygonal tube portion 52c and the polygonal tube portion 53c. The polygonal tube portion 53c is the lower exhaust pipe located below the polygonal tube portion 51c and the polygonal tube portion 54c.

[0217] An outer peripheral surface 266 of the collecting area 260 is formed by the upper surface 61e, the upper surface 64d, the upper surface 64c, the upper surface 63e, the upper surface 63d, the side surface 63b, the side surface 61b, and the upper surface 61d. An outer shape of this outer peripheral surface 266 is approximately triangular.

[0218] The merging region 260 is arranged with a vertex region of the triangle described above oriented downwards.

[0219] The outer peripheral surface 266 includes the upper surface 66a, a lower surface 266b, the outer surface 66d, and an inner surface 266c, which are to be formed in the approximate triangle.

[0220] The upper surface 66a and the lower surface 266b are parallel. Since the merging portion 260 is a triangle with one vertex facing downward, the lower surface 266b is shorter in the vehicle width direction than the upper surface 66a when viewed in the axial direction of the merging portion 260.

[0221] In the merging region 260, the polygonal pipe region 51c abuts the two exhaust pipes of the polygonal pipe region 53c and the polygonal pipe region 54c.

[0222] In the merging region 260, the polygonal pipe region 53c abuts the two exhaust pipes of the polygonal pipe region 51c and the polygonal pipe region 54c.

[0223] In the merging region 260, the polygonal pipe region 54c abuts the two exhaust pipes of the polygonal pipe region 51c and the polygonal pipe region 53c.

[0224] That is, in the merging portion 260, respective polygonal pipe portions 51c, 53c, and 54c are arranged with the three pipes in a bundle so as to be in contact with at least two adjacent exhaust pipes.

[0225] The merging pipe 255 is connected to the merging portion 260 by having an inner peripheral surface at an upstream end of the merging pipe 255 fitted to the outer peripheral surface 266 of the collecting portion 260.

[0226] The merging tube 255 covers an entire circumference of the outer peripheral surface 266 of the merging region 260. The merging tube 255 is formed according to the outer peripheral surface 266 of the merging region 260. Viewed in an axial direction of the merging tube 255, an outer shape of the merging tube 255 is an approximately triangular shape similar to the outer peripheral surface 266.

[0227] In detail, the merging tube 255 includes the first surface 71, a second surface 272, a third surface 273, and the fourth surface 74. As viewed in the axial direction of the merging tube 255, the first surface 71 connects the polygonal tube portion 51c and the polygonal tube portion 54c, which are adjacent to each other, in a left and right direction. The second surface 272 covers the lower surface 266b of the merging portion 260. The third surface 273 covers the inner surface 266c of the merging portion 260. The fourth surface 74 connects the polygonal tube portion 54c and the polygonal tube portion 53c, which are adjacent to each other, in the vertical direction.

[0228] The second surface 272 is a lower side portion of the approximately triangular junction tube 255 and is approximately horizontal. In detail, the second surface 272 is slightly inclined so as to be positioned downwards in the vehicle width direction as a head portion.

[0229] The first surface 71 is an upper surface portion of the approximately triangular merging tube 255 and parallel to the second surface 272. The first surface 71 covers the upper surface 66a of the outer peripheral surface 266.

[0230] The fourth surface 74 is an outer surface portion of the approximately triangular merging pipe 255 and is an inclined surface that slopes outward and upward in the vehicle width direction when viewed from the front. The fourth surface 74 covers the upper surface 66d of the outer peripheral surface 266.

[0231] The third surface 273 is an upper surface portion of the approximately triangular merging tube 255 and covers the inner surface 266c of the outer peripheral surface 266.

[0232] On the first surface 71 of the merging pipe 255, the exhaust gas sensor 59 is mounted according to a structure similar to that of the sensor mounting portion 76 ( Fig. 3) attached.

[0233] The polygonal pipe portion 53c is provided like the lower exhaust pipe with the circular pipe 81, which extends to the downstream side into the merging pipe 55.

[0234] The merging tube 255 has a narrowed portion similar to the narrowed portion 75 ( Fig. 7) of the first embodiment described above, on the first surface 71. The exhaust gas sensor 59 is arranged at a rear side of this narrowed area.

[0235] The merging pipe 255 is arranged at the recess area 83c (Fig. 13).

[0236] Exhaust air flowing from the polygonal pipe section 51c to the merging pipe 255 and exhaust air flowing from the polygonal pipe section 54c to the merging pipe 255 directly contact the detection section 59a. Therefore, exhaust air from the first exhaust pipe 51 and the fourth exhaust pipe 54 can be detected by the exhaust sensor 59 with high accuracy.

[0237] Exhaust air flowing from the polygonal pipe portion 53c through the circular pipe 81 to the merging pipe 255 is guided through the circular pipe 81 so as to be aligned with the detection portion 59a and directly contact the detection portion 59a. Therefore, the third exhaust pipe 53 can be detected by the exhaust sensor 59 with high accuracy.

[0238] According to the second embodiment, the motorcycle 1 includes the plurality of the first exhaust pipe 51, the third exhaust pipe 53, and the fourth exhaust pipe 54, the converging portion 260, and the exhaust gas sensor 59. The plurality of the first exhaust pipe 51, the third exhaust pipe 53, and the fourth exhaust pipe 54 are connected to the engine and converged at the converging portion 260. The converging portion 260 is offset outward in the vehicle width direction with respect to the vehicle width center. The respective exhaust pipes of the first exhaust pipe 51, the third exhaust pipe 53, and the fourth exhaust pipe 54 are arranged with the three pipes in a bundle so as to be in contact with two adjacent exhaust pipes in the converging portion 260. The converging pipe 255 covering the entire circumference of the converging portion 260 is arranged. The header pipe 255 extends in the vehicle longitudinal direction.In the front view of the motorcycle 1 in an upright state, a fourth surface 74 as the outer surface of the header pipe 255 is the inclined surface inclined outward and upward in the vehicle width direction. The merging pipe 255 is provided with an exhaust gas sensor 59. Viewed in an axial direction of the merging pipe 255, the merging pipe 255 includes the first surface 71 connecting the two adjacent ones of the first exhaust pipe 51 and the fourth exhaust pipe 54, and a second surface 272 opposite to the first surface 71. The exhaust gas sensor 59 is attached to the first surface 71. The bent portion 81b, which bends toward the exhaust gas sensor 59, is arranged at the end portion on the downstream side of the third exhaust pipe 53, positioned on the second surface 272 side.

[0239] With this configuration, in the converging portion 260, the respective exhaust pipes of the first exhaust pipe 51, the third exhaust pipe 53, and the fourth exhaust pipe 54 are arranged with the three pipes in a bundle so as to be in contact with two adjacent exhaust pipes, and an exhaust gas sensor 59 is disposed. Accordingly, the first exhaust pipe 51, the third exhaust pipe 53, the fourth exhaust pipe 54, and the exhaust gas sensor 59 can be arranged compactly. Moreover, since the fourth surface 74 of the converging pipe 255 is the inclined surface inclined outward and upward in the vehicle width direction, a clearance can be ensured between the converging pipe 255 and a ground G when the motorcycle 1 is banked, and a large bank angle of the motorcycle 1 can be ensured.Furthermore, since the exhaust gas sensor 59 is disposed on the first surface 71 of the converging pipe 255, the exhaust air from the two exhaust pipes 51 and 54 on the first surface 71 side can be detected with high accuracy by the exhaust gas sensor 59. Furthermore, exhaust air from the third exhaust pipe 53 positioned on the second surface 272 side can be guided through the bent portion 81b to pass toward the exhaust gas sensor 59. In view of this, even if an exhaust gas sensor 59 is disposed on the converging pipe 55, the exhaust air can be detected with high accuracy.

[0240] It should be understood that the above-described first and second embodiments are set forth to illustrate one aspect to which the present invention is applied, and the present invention is not limited to the above-described first or second embodiment.

[0241] While it was stated in the first and second embodiments described above that the exhaust gas sensor 59 is arranged downstream of the constricted region 75, the present invention is not limited thereto. The exhaust gas sensor 59 may be arranged at the constricted region 75.

[0242] Furthermore, while only one exhaust gas sensor 59 is provided in the first and second embodiments, the present invention is not limited thereto. Other exhaust gas sensors may be added and arranged on the merging pipes 55 and 255.

[0243] Furthermore, while in the first and second embodiments described above, an example of the motorcycle 1 was presented as the saddle-seat vehicle, the present invention is not limited thereto. The present invention is also applicable to a three-wheeled saddle-seat vehicle having two front wheels or two rear wheels, and a saddle-seat vehicle having four or more wheels. List of reference symbols: 1 motorcycle (saddle-seat vehicle) 3 Rear wheel (wheel) 10 body frames 11 Engine 30 Crankshaft 34 Clutch shaft 51 First exhaust pipe (exhaust pipe, two adjacent exhaust pipes) 51c Polygonal pipe area (polygonal pipe, upper exhaust pipe) 52 Second exhaust pipe (exhaust pipe, exhaust pipe positioned on a second surface side) 52c Polygonal pipe area (polygonal pipe, lower exhaust pipe) 53 Third exhaust pipe (exhaust pipe, exhaust pipe positioned on a second surface side) 53c Polygonal pipe area (polygonal pipe, lower exhaust pipe) 54 Fourth exhaust pipe (exhaust pipe, two adjacent exhaust pipes) 54c Polygonal pipe area (polygonal pipe, upper exhaust pipe) 56 Catalyst device 55, 255 junction pipe 59 exhaust gas sensor 60, 260 merging area 71 First surface (upper surface area) 72, 272 Second surface (lower surface area) 74 Fourth surface (outer surface) 75 Narrowed area 80 Circular pipe (pipe that has a circular cross-sectional area) 80b Curved area 81 Circular pipe (pipe that has a circular cross-sectional area) 81b Curved area 83 Oil pan 83c Recess area

Claims

[1] Saddle-seat vehicle which has: an engine (11); a plurality of exhaust pipes (51, 52, 53 and 54) connected to the engine (11); a merging region (60 and 260) at which the plurality of exhaust pipes (51, 52, 53 and 54) are merged; and an exhaust gas sensor (59), wherein the merging region (60 and 260) is arranged offset outward in a vehicle width direction with respect to a center of a vehicle width, wherein the respective exhaust pipes (51, 52, 53 and 54) are arranged with at least three of the pipes in a bundle so as to be in contact with at least the two adjacent exhaust pipes in the merging region (60 and 260), a merging pipe (55 and 255) covering an entire circumference of the merging area (60 and 260) is arranged, wherein the merging pipe (55 and 255) extends in a vehicle longitudinal direction, in a front view of the saddle-seat vehicle viewed in an upright state, an outer surface (74) of the merging pipe (55 and 255) is an inclined surface inclined outward and upward in the vehicle width direction, the merging pipe (55 and 255) is provided with an exhaust gas sensor (59), viewed in an axial direction of the merging pipe (55 and 255), the merging pipe (55 and 255) has a first surface (71) connecting two adjacent exhaust pipes (51 and 54) and a second surface (72 and 272) opposite to the first surface (71), and the exhaust gas sensor (59) is attached to the first surface (71), a bent portion (80b and 81b) which bends towards the exhaust gas sensor (59) is arranged at an end portion on a downstream side of the exhaust pipe (52 and 53) positioned on the side of the second surface (72 and 72). [2] A saddle seat vehicle according to claim 1, wherein the bent portion (80b and 81b) is a portion where a pipe (80 and 81) having a circular cross-sectional area bends. [3] Saddle-seat vehicle according to claim 1 or 2, wherein the plurality of exhaust pipes (51, 52, 53 and 54) are arranged with four of the pipes in a bundle so that an outer shape of the merging pipe (55) becomes approximately a parallelogram when viewed in the axial direction of the merging pipe (55), and a lower surface area (72) of the merging tube (55) is arranged approximately parallel to the bottom (G). [4] Saddle-seat vehicle according to claim 3, wherein the exhaust pipes (51, 52, 53 and 54) are four pipes to be bundled, the pipes (51c, 52c, 53c and 54c) having respective polygonal cross-sectional areas in the merging region (60), and each of the two polygonal tubes (51c, 52c, 53c and 54c), which are positioned diagonally next to each other, have an identical cross-sectional shape. [5] Saddle-seat vehicle according to one of claims 1 to 4, wherein the exhaust pipes (51, 52, 53 and 54), a plurality of which are bundled, are pipes (51c, 52c, 53c, and 54c) having respective polygonal cross-sectional areas in the merging region (60 and 260), the exhaust pipe (52 and 53) positioned on the side of the second surface (72 and 272) is provided with a circular pipe (80 and 81) extending from polygonal pipes (52c and 53c) into the merging pipe (55 and 255), and the bent portion (80b and 81b) is arranged in the circular tube (80 and 81). [6] Saddle-seat vehicle according to claim 5, wherein the first surface (71) is an upper surface area of ​​the merging tube (55 and 255), and the second surface (72 and 272) is a lower surface area of ​​the merging tube (55 and 255), the exhaust pipes (51, 52, 53 and 54) comprise a pair of upper exhaust pipes (51 and 54) arranged side by side to the left and right in the merging region (60 and 260), and a lower exhaust pipe (52 and 53) arranged below the upper exhaust pipes (51 and 54) in the merging region (60 and 260), and the circular pipe (80 and 81) is arranged in the lower exhaust pipe (52 and 53). [7] Saddle seat vehicle according to one of claims 1 to 5, wherein the first surface (71) is a surface area of ​​the merging tube (55 and 255). [8] Saddle-seat vehicle according to one of claims 1 to 7, wherein the merging pipe (55 and 255) has a narrowed portion (75) in which a diameter is narrowed, and the exhaust gas sensor (59) is arranged at the narrowed portion (75) or at a downstream side of the narrowed portion (75) in a flow of exhaust air, and a body frame (10) overlaps the exhaust gas sensor (59) from an outer side in the vehicle width direction. [9] A saddle-seat vehicle according to any one of claims 1 to 8, wherein a catalyst device (56) is arranged at a rear side of the merging pipe (55 and 255), and the exhaust gas sensor (59) is positioned below the engine (11) and between a crankshaft (30) of the engine (11) and a clutch shaft (34) as viewed in a side view of the vehicle. [10] Saddle-seat vehicle according to one of claims 1 to 9, wherein an oil pan (83) is arranged at a lower region of the engine (11), and the oil pan (83) has a pair of left and right recess portions (83c) opening downward and to outer lateral sides in a front view of the vehicle, and the merging pipe (55 and 255) is arranged at one of the recess areas (83c). [11] Saddle-seat vehicle according to one of claims 1 to 10, wherein the merging pipe (55 and 255) is provided with only one exhaust gas sensor (59). [12] Saddle-seat vehicle according to one of claims 1 to 11, wherein the exhaust gas sensor (59) is arranged at an end portion on a downstream side of the merging pipe (55 and 255).

Images