Saddle type vehicle

Abstract

Disclosed is a saddle vehicle comprising: a power unit P including an internal combustion engine 20 and a transmission 60; a fan 56; and an exhaust pipe 51 and a catalyst device 53 that discharge exhaust gas from an atmosphere opening 52a, in which at least a part of a downstream-side exhaust pipe 51b that is positioned downstream of the catalyst converter 53 and extends rearward of the vehicle body is disposed outward in the vehicle width direction in a vehicle upward view, beyond a unit case Pc of the power unit P, and in a side view of the vehicle, the downstream-side exhaust pipe 51b is disposed outward in the vehicle width direction in the vehicle upward view. The downstream side exhaust pipe 51b is provided with an exhaust gas sensor 54 in front of and below a rotation center C1 of the fan 56, the unit housing Pc has a fan cover 57 covering the fan 56 in a vehicle width direction, and the exhaust gas sensor 54 is disposed so as to at least partially overlap the fan cover 57 in a vehicle side view. According to the saddle type vehicle, the exhaust gas sensor can be preheated in advance, exhaust gas disturbance in a pipeline is restrained, and the precision of the exhaust gas sensor is improved.

Description

Technical Field

[0001] The present utility model relates to a saddle-type vehicle in which an exhaust gas sensor is arranged on an exhaust pipe connected to an internal combustion engine. Background Art

[0002] Traditionally, there is a saddle-type vehicle in which an exhaust gas sensor is provided on an exhaust pipe to measure the oxygen concentration of exhaust gas passing through the exhaust pipe connected to an internal combustion engine. In such a saddle-type vehicle, a cover (such as a fan cover, a muffler cover, etc.) prevents traveling air from hitting the exhaust gas sensor attached to the exhaust pipe, prevents the temperature of the exhaust gas sensor from decreasing, and also prevents an obstacle from hitting the exhaust gas sensor to protect the exhaust gas sensor (Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: JP2019-190355A Summary of the Utility Model

[0006] Technical Problem to be Solved by the Utility Model

[0007] However, in such a saddle-type vehicle, the exhaust gas sensor arranged on the downstream side of the catalyst device is attached to the exhaust pipe near the muffler far from the internal combustion engine, and there is a problem that it is difficult to rapidly preheat in a state where the temperature of the exhaust gas sensor is low when the internal combustion engine or the like is started. In addition, the exhaust gas sensor is attached to the exhaust pipe near the muffler. Therefore, there is a problem that the flow of the exhaust gas in the exhaust pipe is affected by the interference of the external air flowing in from the atmospheric opening port of the muffler.

[0008] Technical Means for Solving the Technical Problem

[0009] The present utility model is made in view of the above problems, and a saddle-type vehicle includes: a power unit including an internal combustion engine and a transmission; a fan that sends external air into the power unit; an exhaust pipe that is connected to the power unit and discharges exhaust gas from an atmospheric opening port; and a catalyst device that purifies exhaust gas, wherein

[0010] the exhaust pipe includes: an upstream side exhaust pipe located on the upstream side of the catalyst device; and a downstream side exhaust pipe located on the downstream side of the catalyst device,

[0011] in a vehicle bottom view, at least a part of the downstream side exhaust pipe extending rearward in the vehicle body is arranged at a position more outward in the vehicle width direction than the unit housing of the power unit,

[0012] in a vehicle side view, the exhaust gas sensor is arranged on the downstream side exhaust pipe at the front lower side of the rotation center of the fan.

[0013] The unit housing includes a fan cover that faces the vehicle width direction and covers the fan, and

[0014] In a side view of the vehicle, the exhaust gas sensor is arranged to at least partially overlap with the fan cover.

[0015] According to the above configuration, the exhaust gas sensor arranged on the downstream side exhaust pipe is arranged near the internal combustion engine, making it easy to quickly preheat using the heat of the internal combustion engine and enabling accurate detection. In addition, the exhaust gas sensor arranged on the downstream side exhaust pipe is arranged at a position immediately upstream of the catalyst device in the exhaust gas flow in the downstream side exhaust pipe. Therefore, the distance between the exhaust gas sensor and the atmospheric opening port of the muffler is relatively long. Thus, when the pressure in the exhaust pipe becomes negative, the influence of the exhaust gas disturbance in the pipe caused by the external air flowing in from the atmospheric opening port can be reduced, and the accuracy of the exhaust gas sensor can be improved.

[0016] In addition, in the present utility model, in a side view of the vehicle, the exhaust gas sensor overlaps with the lower side cover that covers the lower side of the vehicle.

[0017] According to the above configuration, the side surface of the exhaust gas sensor is covered by the lower side cover. Therefore, even when the exhaust gas sensor is arranged on the exhaust pipe that is more outward than the crankcase in the vehicle width direction, the traveling air can be prevented from directly hitting the exhaust gas sensor, and a decrease in the detection accuracy caused by the rapid cooling of the exhaust gas sensor can be prevented.

[0018] In addition, in the present utility model, the fan cover includes an eaves portion that covers the downstream side exhaust pipe.

[0019] According to the above configuration, the occupant can be protected from the influence of the exhaust pipe heated to a high temperature by the exhaust heat, and the clothes of the occupant can be prevented from touching the heated exhaust pipe.

[0020] In addition, in the present utility model, the eaves portion of the fan cover includes a cutout portion that opens in the vehicle front-rear direction, and

[0021] In a side view of the vehicle, the cutout portion overlaps with the exhaust gas sensor.

[0022] According to the above configuration, the cutout portion is provided in the eaves portion of the fan cover. Therefore, when attaching the exhaust gas sensor or the like, tools or the like can be inserted, improving the installation performance and maintenance performance.

[0023] Technical effects of the present utility model

[0024] According to the present utility model, an exhaust gas sensor arranged on the downstream side exhaust pipe is arranged near the internal combustion engine, making it easy to rapidly preheat using the heat of the internal combustion engine and enabling precise detection. In addition, the exhaust gas sensor arranged on the downstream side exhaust pipe is arranged at a position immediately upstream of the catalyst device in the exhaust gas flow in the downstream side exhaust pipe. Therefore, the distance between the exhaust gas sensor and the atmospheric opening port of the muffler is relatively long. Thus, when the pressure in the exhaust pipe becomes negative, the influence of the exhaust gas disturbance in the pipe caused by the external air flowing in from the atmospheric opening port can be reduced, and the accuracy of the exhaust gas sensor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. 6 is a left side view of an entire motorcycle incorporating an intake structure of an internal combustion engine according to an embodiment of the present utility model.

[0026] Figure 2 is Figure 1 an enlarged right side view of a main part of the vehicle.

[0027] Figure 3 is Figure 1 a left side view of a power unit, an intake structure device, and an exhaust device in FIG. 6.

[0028] Figure 4 is Figure 2 a top view of FIG. 18;

[0029] Figure 5 is a bottom view of a main part of the motorcycle.

[0030] Figure 6 is a partial cross-sectional view taken along the crankshaft of the internal combustion engine of the power unit.

[0031] Figure 7 is Figure 1 a right side view of the entire motorcycle in FIG. 36.

[0032] Figure 8 is Figure 2 a view in which a fan cover in FIG. 42 is partially cut away.

[0033] Figure 9 is a perspective view of the fan cover;

[0034] Figure 10 is a perspective view showing the periphery of a cut portion of the fan cover. DETAILED DESCRIPTION OF THE EMBODIMENT

[0035] Hereinafter, a saddle type vehicle according to an embodiment of the present utility model will be described with reference to Figures 1 - 10 FIGS.

[0036] The saddle-type vehicle according to the present embodiment is a step-through motorcycle 1, and a right side view of the motorcycle 1 is shown in Figure 1 .

[0037] Note that in the description of this specification, the front, rear, left, right, upper, and lower directions correspond to normal reference, and the straight-ahead direction of the motorcycle 1 according to the present embodiment is the front side. In the drawings, FR indicates the front side, RE indicates the rear side, LH indicates the left side, RH indicates the right side, UP indicates the upper side, and DW indicates the lower side.

[0038] As Figure 1 shown, a front body portion 1F and a rear body portion 1R of the vehicle body are interconnected by a floor portion 1C, and a body frame F of the frame of the vehicle body mainly includes a down tube 3 and a main tube 4.

[0039] That is to say, the down tube 3 extends downward from a head tube 2 of the front body portion 1F, the down tube 3 is horizontally bent at its lower end, and extends rearward under the floor portion 1C, and at its rear end, a pair of left and right main tubes 4 are connected. In each main tube 4, an inclined portion 4a extending obliquely upward and backward from such a connection portion is formed, and an upper portion of the inclined portion 4a is further bent to form a horizontal portion 4b extending substantially horizontally rearward.

[0040] In the front body portion 1F, the vertically oriented portions of the head tube 2 and the down tube 3 are covered from the front and rear sides by a front cowl 1a and leg guards 1b. In the floor portion 1C, the front and rear oriented portions of the down tube 3 are covered by a lower cowl 1c. In the rear body portion 1R, the left, right, and rear sides of the main tube 4 are covered by a body cowl 1d. As Figure 2 and Figure 7 shown, the lower cowl 1c covering the lower side of the vehicle extends rearward in the vehicle from under the front cowl 1a and partially covers the right side of the power unit P.

[0041] A storage box 5 and a fuel tank (not shown) are supported between a pair of main tubes 4 in the front-rear direction, and a seat 7 is arranged to cover the upper sides of the storage box 5 and the fuel tank.

[0042] On the other hand, in the front body portion 1F, a handlebar 8 is provided on the upper side to be pivotally supported by the head tube 2, a front fork 9 extends downward, and a front wheel 10 is pivotally supported at the lower end of the front fork 9.

[0043] A support bracket 11 is provided to project rearward at approximately half of the longitudinal direction of the inclined portion 4a of the main tube 4. As Figure 2 shown, a hanger 22h projects obliquely upward at the upper portion of the power unit P. The support bracket 11 of the main tube 4 and the hanger 22h are connected via a link member 12, and the power unit P is swingably connected to and supported by the main tube 4 in such a link mechanism.

[0044] Refer to Figure 3, at the front of the power unit P, a single-cylinder, four-stroke, air-cooled internal combustion engine 20 is arranged to project forward to a substantially horizontal state in a generally forwardly inclined posture by overlapping in sequence from the crankcase 22, the cylinder block 23, the cylinder head 24, and the valve cover 25. The crankcase 22 pivotally supports the crankshaft 21 to be oriented in the vehicle width direction.

[0045] Refer to Figure 6 , the crankcase 22 includes a left crankcase portion 22L and a right crankcase portion 22R that are divided into left and right. The left crankcase portion 22L and the right crankcase portion 22R respectively pivotally support the crankshaft 21 oriented in the vehicle width direction rotatably via main bearings 21b and 21b.

[0046] An alternator 55 is provided on the right shaft portion of the crankshaft 21, and a centrifugal cooling fan 56 is integrally attached to the outer rotor 55r of the alternator 55.

[0047] A fan cover 57 that covers the right crankcase portion 22R from the right side houses the centrifugal cooling fan 56 inside. Also refer to Figure 2 , a grille 57g that faces the centrifugal cooling fan 56 and serves as an external air inlet is formed on the fan cover 57.

[0048] As Figure 6 shown, the left crankcase portion 22L extends rearward and also serves as a transmission case portion. A transmission case cover 65 covers this transmission case portion (left crankcase member) 22L from the left side, and a belt-type continuously variable transmission 60 as a transmission device is arranged inside. A drive sprocket 58 is arranged adjacent to the main bearing 21b in the left shaft portion of the crankshaft 21, and a drive pulley 61 of the belt-type continuously variable transmission 60 is arranged in the left shaft end portion.

[0049] Power is transmitted to the valve mechanism on the cylinder head 24 side through a cam chain 59, and the cam chain 59 is wound around the drive sprocket 58.

[0050] Refer to Figure 1 and Figure 3 , the reduction gear output shaft of a reduction mechanism 64 provided at the rear of the belt-type continuously variable transmission 60 serves as a rear wheel shaft 28a, and a rear wheel 28 is provided on the rear wheel shaft 28a.

[0051] A rear buffer (not shown) is interposed between the upper end of the rear portion of the transmission case portion 22L that houses the reduction mechanism 64 and the upper bent portion of the main pipe 4.

[0052] As Figure 3As shown, the driven pulley 63 of the belt-type continuously variable transmission 60 is pivotally supported by the reduction gear input shaft 64a of the reduction mechanism 64. The belt 62 is wound around the drive pulley 61 provided on the crankshaft 21 and the driven pulley 63 provided on the reduction gear input shaft 64a. The power of the internal combustion engine 20 is transmitted to the driven pulley 63 through the belt 62. The rotation of the driven pulley 63 is transmitted to the reduction gear input shaft 64a of the reduction mechanism 64 through a centrifugal clutch (not shown), decelerated by the reduction mechanism 64, and the power is transmitted to the rear wheel 28. As Figure 6 shown, an external intake fan 61F is formed in the pulley half on the left side of the drive pulley 61.

[0053] As Figure 6 shown, the shroud 70 surrounds the cylinder block 23 and the cylinder head 24, and the shroud 70 is coupled to the fan shroud 57 on the right side.

[0054] Referring to FIG. 3, an intake port 24a is formed on the upper surface side of the cylinder head 24 of the internal combustion engine 20 in the front part of the power unit P, and an intake pipe 31 serving as an intake pipe extends upward from the intake port 24a. An exhaust port 24b is formed on the lower surface side of the cylinder head 24, and an exhaust pipe 51 extends downward from the exhaust port 24b.

[0055] In addition, a spark plug 26 is mounted and inserted into the cylinder head 24 so as to be close to the center cover 25. In addition, an oxygen concentration sensor 27 is mounted and inserted at the position where the exhaust pipe 51 extends.

[0056] The intake device 30 is connected to the intake port 24a of the internal combustion engine 20. The intake device 30 sucks in external air and sends the external air into the internal combustion engine 20. The inside of the intake device 30 serves as an intake passage, and the intake air is sent into the internal combustion engine 20 through this intake passage. The internal combustion engine 20 introduces the intake air into the combustion chamber 20a of the internal combustion engine 20.

[0057] The intake device 30 includes: an air filter device 40 that sucks in and purifies external air; a connecting pipe 36 that is coupled to the air filter device 40; a throttle body 33 that is coupled to the downstream side of the connecting pipe 36; and an intake pipe 31 that is connected to the upstream side of the throttle body 33. A butterfly throttle valve (not shown) is provided inside the throttle body 33, so that these components constitute an intake system.

[0058] As Figure 4As shown, in the air cleaner device 40 of the intake device 30, the air cleaner housing 41 (where the unpurified chamber housing 42 on the left and the purified chamber housing 43 on the right are integrated with each other) is separated by a partition portion 45. The partition portion 45 is provided between the unpurified chamber housing 42 and the purified chamber housing 43, and an air cleaner element 44 is provided therein such that the air cleaner element 44 is divided into an unpurified chamber Ca on the unpurified chamber housing 42 side and a purified chamber Cb on the purified chamber housing 43 side.

[0059] As Figure 3 shown, in the unpurified chamber housing 42, an air introduction pipe 47 is provided with an opening 47a facing forward, and running air or the like is sucked into the air introduction pipe 47. The intake air that has been introduced from the opening 47a passes through the air cleaner element 44 inside the unpurified chamber Ca and is purified, and then is sent to the purified chamber Cb. The purified chamber Cb of the air cleaner device 40 communicates with the throttle body 33 through a connecting pipe 36 made of rubber and elastically deformable. The fuel injection valve 37 is attached to the corresponding upper surfaces of the throttle body 33 and the intake pipe 31, and fuel is injected into the intake passage.

[0060] As Figure 5 shown, the exhaust device 50 is connected to the exhaust port 24b of the cylinder head 24. The exhaust device 50 includes: an exhaust pipe 51 connected to the exhaust port 24b; a muffler 52 connected to the rear end of the exhaust pipe 51 and including an atmospheric opening port 52a facing the rear side of the vehicle; and a catalyst device 53 integrated in the middle of the exhaust pipe 51.

[0061] The exhaust gas discharged from the internal combustion engine 20 flows from the exhaust port 24b into the exhaust pipe 51, is purified by the catalyst device 53 provided in the middle of the exhaust pipe 51, passes through the muffler 52, and is discharged into the atmosphere from the atmospheric opening port 52a.

[0062] The exhaust pipe 51 communicates with the exhaust port 24b, extends downward from the lower surface of the cylinder head 24, bends obliquely forward to the left, further bends from the rear side to the rear side, bends from the left side to the right side under the crankcase 22, extends backward, and is connected to the muffler 52 arranged on the right side of the rear wheel 28.

[0063] The exhaust pipe 51 includes: an exhaust pipe 51c that houses the catalyst device, and the catalyst device 53 is integrated in the middle of the exhaust pipe 51c; an upstream side exhaust pipe 51a connected to the upstream side of the exhaust pipe 51c that houses the catalyst device; and a downstream side exhaust pipe 51b connected to the downstream side of the exhaust pipe 51c that houses the catalyst device.

[0064] The upstream side exhaust pipe 51a communicates with the exhaust port 24b and extends downward from the lower surface of the cylinder head 24 (also refer to Figure 3), then bends obliquely forward to the left, further bends from the rear side to the right side, and is connected to the exhaust pipe 51c that houses the catalyst device.

[0065] The exhaust pipe 51c that houses the catalyst device is located below the internal combustion engine 20, is oriented in the vehicle width direction, and is arranged such that the exhaust gas flows from the right side to the left side of the vehicle.

[0066] The exhaust pipe 51c that houses the catalyst device is arranged in such a way that the upstream end is located on the left side in the vehicle width direction and the downstream end is located on the right side in the vehicle width direction. The upstream end is connected to the upstream side exhaust pipe 51a, and the downstream end is connected to the downstream side exhaust pipe 51b.

[0067] The catalyst device 53 is housed inside the exhaust pipe 51c that houses the catalyst device such that its axis is oriented in the vehicle width direction. The catalyst device 53 is a honeycomb porous structure having a large number of holes extending in its axial direction, and carries components such as platinum, rhodium, palladium, etc. as components for decomposing exhaust gas.

[0068] As Figure 5 shown, the downstream side exhaust pipe 51b is connected to the downstream side of the exhaust pipe 51c that houses the catalyst device, extends in the vehicle width direction, and then bends backward. In the vehicle bottom view, the downstream side exhaust pipe 51b extends backward along the vehicle longitudinal direction at a position more outside in the vehicle width direction than the crankcase 22, which constitutes the unit housing Pc. In addition, as Figure 2 and Figure 7 shown, in the vehicle right side view, the downstream side exhaust pipe 51b extends backward from the left side of the lower side of the power unit P, then bends and extends obliquely upward, and is coupled to the muffler 52 arranged on the right side of the rear wheel 28.

[0069] Figure 8 is a right side view of the main part near the power unit P in a state where the front side of the fan shroud 57 is partially cut away. The downstream side exhaust pipe 51b includes two bending portions 51d located on the upstream side and the downstream side in the side view. The downstream side exhaust pipe 51b is formed in such a way that the upstream side bending portion 51d of the bending portion 51d closest to the exhaust pipe 51c that houses the catalyst device 1 is located on the front side with respect to the rotation center C1 of the cooling fan in the vehicle longitudinal direction in the vehicle side view.

[0070] The saddle-type vehicle in this embodiment includes two bending portions 51d. However, it is sufficient to include at least one bending portion 51d, or two or more bending portions 51d may be included.

[0071] An exhaust gas sensor 54 is attached to the downstream side exhaust pipe 51b and detects the oxygen concentration in the exhaust gas that has passed through the catalyst device 53. The exhaust gas sensor 54 is a LAF sensor or an O 2 sensor.

[0072] As Figure 2 and Figure 6 shown, a fan shroud 57 is provided to be located near the downstream side exhaust pipe 51b and the exhaust gas sensor 54, and forms a part of the unit housing Pc to cover the right side of the centrifugal cooling fan 56. The fan shroud 57 is integrally coupled with a shroud 70 that covers a part of the periphery of the internal combustion engine 20 and covers the right side surface of the internal combustion engine 20.

[0073] The fan shroud 57 will be described in detail. Figure 9 is a perspective view of the fan shroud 57; the fan shroud 57 includes a side wall portion 57a that covers the right side surface of the fan shroud. In the side wall portion 57a, a grille 57g is formed in a circular shape centered on the rotation center C1 of the centrifugal cooling fan 56 (refer to Figure 6 ), and the rotation of the centrifugal cooling fan 56 causes external air to pass through the grille 57g and be sucked into the power unit P.

[0074] At the upper and rear portions of the circumferential edge of the side wall portion 57a, a circumferential wall portion 57b stands upright from the side wall portion 57a toward the internal combustion engine 20 side. The front edge of the side wall portion 57a and the circumferential wall portion 57b serves as a shroud engaging edge portion 57c that engages with the shroud 70.

[0075] An eaves portion 57d that substantially covers the upper half of the downstream side exhaust pipe 51b is formed at the lower portion of the side wall portion 57a along the downstream side exhaust pipe 51b. In addition, as Figure 2 shown, in the vehicle longitudinal direction, the eaves portion 57d is formed to be longer than the width of the side wall portion 57a and extends in the vehicle longitudinal direction. The eaves portion 57d is formed in such a manner that its front end extends to cover the upstream side bent portion 51d of the downstream side exhaust pipe 51b 1 , and its rear end extends to the vicinity of the bent portion 51d on the rear side of the downstream side exhaust pipe 51b.

[0076] Referring to Figure 9 , the eaves portion 57d includes: an extension portion 57d 1 , which extends outward from the side wall portion 57a in the vehicle width direction; a bent portion 57d 2 , which extends downward from the extension portion 57d in a bent shape 1 ; and a side wall portion 57d 3 , which extends downward from the bent portion 57d 2 and is formed to cover the right side surface of the downstream side exhaust pipe 51b.

[0077] The extension portion 57d1 is formed to extend toward the rear side of the vehicle, such that the width of the rear end edge thereof increases. Also referring to Figure 2 , the bent portion 57d 2 and the side wall portion 57d 3 extend toward the rear side of the vehicle, such that the width of their rear end edges increases, and the downstream end of the side wall portion 57d 3 extends to the vicinity of the bent portion 51d behind the downstream side exhaust pipe 51b. Further, the front portion of the side wall portion 57d 3 bends inward in the vehicle width direction along the downstream side exhaust pipe 51b.

[0078] As Figure 9 shown, a cutout portion 57e that opens forward in the vehicle front-rear direction is formed in the extending portion 57d of the eaves portion 57d 1 and the front side end edge of the bent portion 57d 2 . As Figure 10 shown, the cutout portion 57e is formed so as to avoid the exhaust gas sensor 54 attached to the downstream side exhaust pipe 51b, and as Figure 2 and Figure 9 shown, the cutout portion 57e and the exhaust gas sensor 54 overlap each other in the vehicle side view.

[0079] As Figure 9 shown, an inclined portion 57f is provided in the cutout portion 57e, and the inclined portion 57f inclines toward the depth side such that the opening gradually expands. When the fan cover 57 is detached from the vehicle, it prevents the exhaust gas sensor 54 from hitting the fan cover 57 and makes it difficult to detach the fan cover 57. The temperature of the exhaust gas sensor 54 becomes high, and the fan cover 57 is arranged to be spaced from the exhaust gas sensor 54 by about 10 mm.

[0080] Figure 8 is a view in which a part of the eaves portion 57d of the fan cover 57 is cut away so that the exhaust gas sensor 54 attached to the downstream side exhaust pipe 51b can be seen. As Figure 8 and Figure 10 shown, the exhaust gas sensor 54 is attached to the downstream side exhaust pipe 51b so as to be inserted downward from its upper surface. As Figure 8 shown, in the vehicle side view, the exhaust gas sensor 54 is located at the front lower side of the rotation center C1 of the centrifugal cooling fan 56, and is arranged to at least partially overlap the fan cover 57, as Figure 2 shown.

[0081] Further, as Figure 7 and Figure 8 shown, in the vehicle side view, the exhaust gas sensor 54 at least partially overlaps the lower side cover 1c, and prevents impacts from flying stones etc. from the lateral side of the vehicle.

[0082] In addition, in the side view of the vehicle, the exhaust gas sensor 54 is attached to the area surrounded by the dotted line L1, the dotted line L2, and the dotted line L3 in the upstream side exhaust pipe 51a, where the dotted line L1 connects the rotation center C1 of the centrifugal cooling fan 56 to the upstream side bent portion 51d 1 , the dotted line L2 connects the catalyst center point C2 to the rotation center C1 in the side view of the catalyst device 53, and the dotted line L3 connects the catalyst center point C2 to the upstream side bent portion 51d 1 .

[0083] The exhaust gas sensor 54 is arranged as described above. The exhaust gas sensor 54 is arranged close to the catalyst device 53 having a high temperature, and the exhaust gas sensor 54 is quickly preheated and activated, so that the accuracy of the exhaust gas sensor 54 can be improved.

[0084] In addition, as Figure 8 shown, the exhaust gas sensor 54 is positioned at a distance from the atmospheric opening port 52a of the muffler 52. Therefore, when the pressure in the exhaust pipe 51 becomes negative pressure, the exhaust gas disturbance caused by the outside air flowing into the exhaust pipe is less likely to affect the exhaust gas sensor 54.

[0085] As Figure 1 shown, in the motorcycle 1 of the present embodiment, the power unit P is swingably supported by the main pipe 4 of the body frame F via the link member 12 above the power unit P. However, the power unit P can be swingably supported by the body frame F via the link member 12 below the power unit P. On the other hand, from the viewpoint of the assembling performance of the power unit and from the viewpoint of arranging the catalyst device and the exhaust gas sensor in a compact manner, the power unit is swingably supported by the body frame F above the power unit.

[0086] The saddle-type vehicle according to an embodiment of the present invention is configured as described above and achieves the following effects.

[0087] The motorcycle 1 of the present embodiment includes: a power unit P including an internal combustion engine 20 and a belt-type continuously variable transmission 60; a centrifugal cooling fan 56 that sends outside air into the power unit P; an exhaust pipe 51 that is connected to the power unit P and discharges exhaust gas from the atmospheric opening port 52a of the muffler 52; and a catalyst device 53 that purifies the exhaust gas. The exhaust pipe 51 includes: an upstream side exhaust pipe 51a on the upstream side of the catalyst device 53 and a downstream side exhaust pipe 51b on the downstream side of the catalyst device 53. In the bottom view of the vehicle, the downstream side exhaust pipe 51b extending rearward in the vehicle body is at least partially arranged at a position outside the unit housing Pc in the vehicle width direction. The unit housing Pc includes a fan cover 57 that faces the vehicle width direction and covers the centrifugal cooling fan 56, and in the side view of the vehicle, the exhaust gas sensor 54 is arranged to at least partially overlap with the fan cover 57.

[0088] According to the above configuration, the exhaust gas sensor 54 disposed on the downstream side exhaust pipe 51b is disposed near the internal combustion engine 20, making it easy to quickly preheat using the heat of the internal combustion engine 20 and enabling accurate detection. Further, the exhaust gas sensor 54 provided on the downstream side exhaust pipe 51b is disposed at a position immediately upstream of the catalyst device 53 in the exhaust gas flow in the downstream side exhaust pipe 51b, and thus the distance between the exhaust gas sensor 54 and the atmospheric opening port 52a of the muffler 52 is long. Therefore, when the pressure in the exhaust pipe 51 becomes negative, the influence of the exhaust gas disturbance in the pipe caused by the outside air flowing in from the atmospheric opening port 52a can be reduced, and the accuracy of the exhaust gas sensor 54 can be improved.

[0089] In addition, in a side view of the vehicle, the exhaust gas sensor 54 overlaps with the lower side cover 1c covering the lower side of the vehicle, and thus the side surface of the exhaust gas sensor 54 is covered by the lower side cover 1c. Therefore, even when the exhaust gas sensor 54 is disposed on the exhaust pipe 51 located more outside than the crankcase 22 in the vehicle width direction, it is possible to prevent the running air from directly hitting the exhaust gas sensor 54 and to prevent a decrease in the detection accuracy caused by rapid cooling of the exhaust gas sensor 54.

[0090] In addition, the fan cover 57 includes an eaves portion 57d covering the downstream side exhaust pipe 51b. Therefore, it is possible to protect the occupant from the influence of the exhaust pipe 51 heated to a high temperature by the exhaust heat and to prevent the occupant's clothes or the like from coming into contact with the heated exhaust pipe 51.

[0091] In addition, the eaves portion 57d of the fan cover 57 includes a cutout portion 57e that is open in the vehicle front-rear direction, and in a side view of the vehicle, the cutout portion 57e overlaps with the exhaust gas sensor 54. Therefore, since the cutout portion 57e is provided in the eaves portion 57d of the fan cover 57, it is possible to insert a tool or the like when attaching the exhaust gas sensor 54 or the like, thereby improving the installation performance and the maintenance performance.

[0092] As described above, the intake structure of the internal combustion engine according to an embodiment of the present invention has been described. However, each aspect of the present invention is not limited to the above-described embodiment, and also includes implementation modes of each aspect within the scope of the gist of the present invention.

[0093] List of reference signs

[0094] P Power unit

[0095] Pc Unit housing

[0096] C1 Center of rotation

[0097] 1c Lower side cover

[0098] 20 Internal combustion engine

[0099] 51 Exhaust pipe

[0100] 51a Upstream exhaust pipe

[0101] 51b Downstream exhaust pipe

[0102] 52a Atmosphere opening port

[0103] 53 Catalyst device

[0104] 54 Exhaust gas sensor

[0105] 56 Centrifugal cooling fan

[0106] 57 Fan cover

[0107] 57d Eaves

[0108] 57e Notch portion

[0109] 60 Belt-type continuously variable transmission

Claims

1. A saddle-type vehicle, characterized in that, comprising: a power unit (P) including an internal combustion engine (20) and a transmission (60); a fan (56) for sending external air into the power unit (P); an exhaust pipe (51) connected to the power unit (P) and discharging exhaust gas from an atmospheric opening port (52a); and a catalyst device (53) for purifying the exhaust gas, wherein the exhaust pipe (51) includes: an upstream exhaust pipe (51a) located on the upstream side of the catalyst device (53); and a downstream exhaust pipe (51b) located on the downstream side of the catalyst device (53), in a plan view of the vehicle, the downstream exhaust pipe (51b) extending rearward in the vehicle body is at least partially disposed at a position outside the unit housing (Pc) of the power unit (P) in the vehicle width direction, in a side view of the vehicle, an exhaust gas sensor (54) is disposed on the downstream exhaust pipe (51b) at the front lower side of the rotation center (C1) of the fan (56), the unit housing (Pc) includes a fan cover (57) facing the vehicle width direction and covering the fan (56), and in a side view of the vehicle, the exhaust gas sensor (54) is disposed so as to at least partially overlap the fan cover (57).

2. The saddle-type vehicle according to claim 1, characterized in that, in the side view of the vehicle, the exhaust gas sensor (54) overlaps a lower cover (1c) covering the lower side of the vehicle.

3. The saddle-type vehicle according to claim 1 or 2, characterized in that, the fan cover (57) includes an eaves portion (57d) covering the downstream exhaust pipe (51b).

4. The saddle-type vehicle according to claim 3, characterized in that, the eaves portion (57d) of the fan cover (57) includes a cutout portion (57e) opening in the vehicle front-rear direction, and in the side view of the vehicle, the cutout portion (57e) overlaps the exhaust gas sensor (54).

Images