Saddle type vehicle

Abstract

The invention provides a saddle type vehicle. In a saddle-type vehicle, an engine unit including a unit-type swing engine, a catalyst device, and an exhaust gas sensor is made compact. A saddled vehicle is provided with: a unit swing engine (13) that has a crankcase (43) and a cylinder section (44) that extends from the crankcase (43) such that the cylinder axis extends in the front-rear direction of the vehicle, the unit swing engine (13) being swingably supported by a vehicle body frame (12); a radiator (60) disposed on the side of the crankcase (43); an exhaust pipe (77) connected to the cylinder section (44); a catalyst device (121) provided in the exhaust pipe (77); and an exhaust gas sensor (141) provided to the exhaust pipe (77), the catalyst device (121) and the exhaust gas sensor (141) being disposed apart from the radiator in the vehicle front-rear direction in a side view.

Description

[0001] This application is a divisional application of the invention patent application filed on January 31, 2019, with application number 201910095455.9 and invention title "Saddle-type Vehicle". Technical Field

[0002] This invention relates to saddle-type vehicles. Background Technology

[0003] Previously, it was known that in a saddle-type vehicle having a single-cylinder oscillating engine with the cylinder section extending in the longitudinal direction and a radiator disposed on the side of the single-cylinder oscillating engine, a catalyst device and an exhaust gas sensor were disposed below the radiator when viewed from the side (for example, see Figures 29 and 30 of Patent Document 1).

[0004] Patent Document 1: International Publication No. 2016 / 002955 Summary of the Invention

[0005] The object of the present invention is to enable easy access to the swing shaft in a saddle-type vehicle in which the unit swing engine can swing via the swing shaft located at the top of the unit swing engine.

[0006] The saddle-type vehicle of the present invention comprises: a unit-type oscillating engine 13 having a crankcase 43 and a cylinder section 44, the cylinder section 44 extending from the crankcase 43 along a cylinder axis 44a in the longitudinal direction of the vehicle, the unit-type oscillating engine 13 being supported on a body frame 12 in an oscillating manner; a radiator 60 disposed to the side of the crankcase 43; an exhaust pipe 77 connected to the cylinder section 44; a catalyst device 121 disposed on the exhaust pipe 77; and exhaust gas sensors 141, 241, and 341 disposed on the exhaust pipe 77, characterized in that, when viewed from the side, the catalyst device 121 and the exhaust gas sensors 141, 241, and 341 are separately disposed relative to the radiator 60 in the longitudinal direction of the vehicle.

[0007] Furthermore, the invention described above can be configured such that the unit-type oscillating engine 13 is supported on the vehicle frame 12 in an oscillating manner by a connecting portion 48 provided above the unit-type oscillating engine 13, and the catalyst device 121 is disposed in front of the crankcase 43 and below the cylinder portion 44.

[0008] Furthermore, the invention described above can be configured such that the exhaust pipe 77 has a downstream exhaust pipe 122 located downstream of the catalyst device 121, and the exhaust gas sensors 141, 241, and 341 are disposed at the downstream exhaust pipe 122.

[0009] Furthermore, the invention described above can be configured such that the radiator 60 is tilted so that its leading edge 107a is tilted backward when viewed from the side, the uppermost end of the front end 122a of the downstream exhaust pipe 122 is located above the lowermost end 60a of the radiator 60, and the exhaust gas sensor 241 is located at the front end 122a of the downstream exhaust pipe 122 above the lowermost end 60a of the radiator 60.

[0010] Furthermore, the invention described above can be configured such that the downstream exhaust pipe 122 has a bend 128 that bends rearward from the downstream end of the catalyst device 121, the exhaust gas sensor 241 is disposed in front of the radiator 60 at the bend 128, and the exhaust gas sensor 241 coincides with the catalyst device 121 when viewed from the side.

[0011] Furthermore, the invention described above can be configured such that the crankcase 43 has an oil inlet 150 and a cover 151 that closes the oil inlet 150, and the exhaust gas sensors 141 and 341 are disposed below the cover 151 behind the radiator 60.

[0012] Furthermore, the invention described above can be configured such that the axis 141d of the exhaust gas sensors 141 and 341 intersects with the axis 151a of the cover 151 when viewed from the side.

[0013] Furthermore, the above invention can be configured such that the exhaust gas sensors 141, 241, and 341 have a detection portion 141a for detecting exhaust gas and a terminal portion 141b protruding to the outside of the downstream exhaust pipe 122, and the exhaust gas sensors (141, 241, and 341) are configured with the terminal portion 141b positioned above the detection portion 141a.

[0014] Furthermore, the invention described above can be configured such that the exhaust gas sensor 141 is arranged along the direction of the exhaust flow.

[0015] Invention Effects

[0016] According to the present invention, a saddle-type vehicle comprises: a single-unit oscillating engine having a crankcase and a cylinder section extending from the crankcase along the longitudinal direction of the vehicle via a cylinder axis; the single-unit oscillating engine being supported on a vehicle frame in an oscillating manner; a radiator disposed to the side of the crankcase; an exhaust pipe connected to the cylinder section; a catalyst device disposed in the exhaust pipe; and an exhaust gas sensor disposed in the exhaust pipe, wherein, when viewed from the side, the catalyst device and the exhaust gas sensor are separately disposed relative to the radiator in the longitudinal direction of the vehicle.

[0017] According to this structure, the catalyst unit and the exhaust gas sensor are positioned away from the radiator in the front-rear direction of the vehicle, thus enabling the catalyst unit, exhaust gas sensor and radiator to be compactly arranged in the vertical direction.

[0018] Furthermore, the invention described above can be configured such that the unitary oscillating engine is supported on the vehicle frame in an oscillating manner via a connecting portion located above the unitary oscillating engine, and the catalyst device is positioned below the cylinder head in front of the crankcase. According to this structure, the connecting portion is located above the unitary oscillating engine, thus easily ensuring space below the cylinder head. Therefore, the catalyst device can be efficiently positioned using the space below the cylinder head.

[0019] Furthermore, the invention can be configured such that the exhaust pipe has a downstream exhaust pipe located downstream of the catalyst unit, and the exhaust gas sensor is disposed at the downstream exhaust pipe. According to this configuration, the exhaust gas sensor can be used to detect the exhaust gas passing through the catalyst unit.

[0020] Furthermore, the invention can be configured such that the radiator is tilted backwards at its leading edge when viewed from the side, the uppermost end of the front end of the downstream exhaust pipe is positioned above the lowermost end of the radiator, and the exhaust gas sensor is positioned above the lowermost end of the radiator at the front end of the downstream exhaust pipe. According to this structure, the exhaust gas sensor can be compactly arranged at the front end of the downstream exhaust pipe in the vertical direction.

[0021] Furthermore, the invention described above can be configured such that the downstream exhaust pipe has a bend that curves rearward from the downstream end of the catalyst unit, and the exhaust gas sensor is disposed at the bend in front of the radiator, and the exhaust gas sensor coincides with the catalyst unit when viewed from the side. According to this structure, the exhaust gas sensor can be disposed at the bend in front of the radiator in a manner that moves away from the radiator. Furthermore, the exhaust gas sensor can be compactly configured so that it coincides with the catalyst unit when viewed from the side.

[0022] Furthermore, the invention described above can be configured such that the crankcase has an oil filler port and a cover that seals the oil filler port, with the exhaust gas sensor positioned below the cover behind the radiator. According to this structure, the exhaust gas sensor can be efficiently positioned behind the radiator using the space below the cover.

[0023] Furthermore, the invention can be configured such that the axis of the exhaust gas sensor intersects the axis of the cover when viewed from the side. According to this structure, the exhaust gas sensor is less likely to obstruct contact with the cover, making it easier to access the cover.

[0024] Furthermore, the above-described invention can be configured such that the exhaust gas sensor has a detection section for detecting exhaust gas and a terminal section protruding to the outside of the downstream exhaust pipe, with the exhaust gas sensor arranged such that the terminal section is positioned above the detection section. According to this structure, downward protrusion of the exhaust gas sensor can be suppressed, allowing for a compact configuration of the exhaust gas sensor.

[0025] Furthermore, the above invention can be configured such that the exhaust gas sensor is arranged along the direction of the exhaust flow. According to this structure, the exhaust gas sensor's ability to disrupt the exhaust flow can be suppressed, making it easier to detect exhaust gas using the exhaust gas sensor. Attached Figure Description

[0026] Figure 1 This is a right-side view of the automatic two-wheeled vehicle according to the first embodiment of the present invention.

[0027] Figure 2 This is a right-side view of the rear of an automatic two-wheeled vehicle.

[0028] Figure 3 This is a right-side view of a unit-type oscillating engine.

[0029] Figure 4 This is a three-dimensional diagram of a unit-type oscillating engine.

[0030] Figure 5 This is a cross-sectional view of a unit-type oscillating engine.

[0031] Figure 6 This is a right-side view showing the cooling structure of the engine block.

[0032] Figure 7 This is a right-side view of the cylinder head.

[0033] Figure 8 This is a view of the cylinder head from the rear crankcase side.

[0034] Figure 9 It is along Figure 3 A cross-sectional view of the IX-IX line.

[0035] Figure 10 This is a top view of the cylinder head.

[0036] Figure 11 This is a diagram showing the pump cover as viewed from the pump housing side.

[0037] Figure 12 This is a three-dimensional view of the pump housing viewed from the cylinder head side.

[0038] Figure 13 This is a diagram showing the unit-type oscillating engine and its peripheral parts from below.

[0039] Figure 14This is a top view of the exhaust pipe from above.

[0040] Figure 15 This is a three-dimensional view of the exhaust pipe from the right side.

[0041] Figure 16 This is a right-side view of the periphery of the radiator and linkage mechanism.

[0042] Figure 17 This is a view of the periphery of the radiator and linkage mechanism from above.

[0043] Figure 18 This is a three-dimensional view of the periphery of the oil filler port as seen from above.

[0044] Figure 19 This is a top view of the exhaust pipe viewed from above in a variation of the first embodiment.

[0045] Figure 20 This is a three-dimensional view of the exhaust pipe viewed from the right side in a modified example.

[0046] Figure 21 This is a right-side view of the periphery of the radiator and linkage mechanism in the second embodiment.

[0047] Figure 22 This is a diagram of the unit-type oscillating engine and its peripheral portion as viewed from below in the second embodiment.

[0048] Label Explanation

[0049] 1: Automatic two-wheeled vehicle (saddle-riding type vehicle); 12: Frame; 13: Unit-type oscillating engine; 43: Crankcase; 44: Cylinder section; 44a: Cylinder axis; 48: Connecting rod mechanism (connecting part); 60: Radiator; 60a: Lowermost end; 77: Exhaust pipe; 107a: Leading edge; 121: Catalyst device; 122: Downstream exhaust pipe; 122a: Front end; 128: Bent section; 141, 241, 341: Downstream exhaust gas sensor (exhaust gas sensor); 141a: Detection part; 141b: Terminal part; 141d: Axis; 150: Oil filler port; 151: Cover; 151a: Axis (axis of the cover). Detailed Implementation

[0050] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description, unless otherwise specified, directions such as front, back, left, right, and up / down refer to directions relative to the vehicle body. Furthermore, in each figure, the reference numeral "front" indicates the front of the vehicle body, "up" indicates the top of the vehicle body, and "right" indicates the right side of the vehicle body.

[0051] (First Embodiment)

[0052] Figure 1 This is a right-side view of the automatic two-wheeled vehicle according to the first embodiment of the present invention. Additionally, in Figure 1 In the image, only the left-side component is shown for components that are arranged in pairs on the left and right.

[0053] The automatic two-wheeled vehicle 1 is a pedal-type saddle-riding vehicle with a low-floor footrest 11 for the occupant to place their feet on the seat 10. The automatic two-wheeled vehicle 1 has a front wheel 2 at the front of the body frame 12 (body), and the rear wheel 3, which serves as the drive wheel, is mounted on a single-unit swing engine 13 (internal combustion engine, motor) axle at the rear of the vehicle.

[0054] The automatic two-wheeled vehicle 1 has a front fork 14 that is axled on the front end of the vehicle frame 12, and a front wheel 2 that is axled on the lower end of the front fork 14. The handlebars 15 operated by the rider are mounted on the upper end of the front fork 14.

[0055] The automatic two-wheeled vehicle 1 is equipped with a body cover 16 that covers the vehicle body, including the vehicle frame 12.

[0056] The vehicle frame 12 has: a front riser 17 disposed at the front end; a lower frame 18 extending rearward and downward from the front riser 17; a pair of left and right bottom frames 19, 19 extending generally horizontally rearward from the lower end of the lower frame 18; and a pair of left and right seat frames 20, 20 extending from the rear end of the bottom frames 19, 19 in a low-front-high-rear manner.

[0057] The bottom frame 19, 19 and the seat frame 20, 20 are tubular, extending in the front-to-back direction.

[0058] Each seat frame 20 has: an upright portion 21 that extends from the rear end of each bottom frame 19 in a forward-lower, rear-higher manner; and a rear extension portion 22 that extends from the upper end of the upright portion 21 to the rear end of the body frame 12. The rear extension portion 22 extends at a gentler slope than the upright portion 21, in a forward-lower, rear-higher manner.

[0059] The vehicle frame 12 has: a crossbeam 23 connecting the rear ends of the bottom frames 19, 19 in the vehicle width direction; an upper crossbeam 24 connecting the upper parts of the uprights 21, 21 in the vehicle width direction; and a pair of left and right support frames 25, 25 extending rearward from the uprights 21, 21.

[0060] In addition, the vehicle frame 12 has a pair of engine brackets 26, 26 protruding rearward from the upright portion 21 of the seat frames 20, 20.

[0061] Above the unit-type oscillating motor 13 and between the left and right seat frames 20, a storage box 27 is provided to hold items such as helmets. The seat 10 is supported on the upper surface of the storage box 27 and covers the opening of the upper surface of the storage box 27.

[0062] The vehicle cover 16 has: an upper cover 30 covering the periphery of the handlebars 15; a front cover 31 covering the front head tube 17 and the underframe 18 from the front and sides; and a leg guard 32 covering the front head tube 17 and the underframe 18 from the rear, in close contact with the front cover 31.

[0063] In addition, the body cover 16 has: a bottom cover 33 that covers the bottom frame 19, 19 from below; foot pedals 11 that cover the bottom frame 19, 19 from above; a pair of left and right side covers 34 that cover the seat frame 20, 20 and housing 27 from the side below the seat 10; and a central bottom cover 35 that covers the housing 27 and unit swing engine 13 from the front below the seat 10.

[0064] In addition, the automatic two-wheeled vehicle 1 has a front fender 36 that covers the front wheel 2 from above.

[0065] Figure 2 This is a right-side view of the rear of the automatic two-wheeled vehicle 1. Figure 3 This is a right-side view of the unit-type oscillating engine 13. Figure 4 This is a three-dimensional view of the unit-type oscillating engine 13.

[0066] The unit-type oscillating engine 13 is a combined oscillating power unit that integrates the engine body 40, which serves as the drive source, with the arm 41 that supports the rear wheel 3.

[0067] The rear wheel 3 is supported by the rear wheel axle 3a at the rear end of the arm 41.

[0068] The engine body 40 has: a crankcase 43 that houses a crankshaft 42 extending in the vehicle width direction; and a cylinder section 44 extending forward from the crankcase 43.

[0069] The cylinder section 44 includes, from the crankcase 43 side, a cylinder 45, a cylinder head 46, and a cover 47 in sequence.

[0070] The engine body 40 is a horizontal engine in which the cylinder axis 44a of the cylinder section 44 extends approximately horizontally in the longitudinal direction of the vehicle. In detail, when viewed from the side, the cylinder section 44 extends approximately horizontally forward of the vehicle with a slightly higher front and lower rear.

[0071] The unit-type oscillating engine 13 is supported on the vehicle frame 12 in an oscillating manner by means of a linkage mechanism 48 (connecting part) disposed above the unit-type oscillating engine 13.

[0072] The linkage mechanism 48 includes: a swing shaft 48a connected to the upper part of the crankcase 43; a pair of left and right body-side swing shafts 48b, 48b connected to the engine brackets 26, 26 of the seat frames 20, 20; and a connecting rod member 48c connecting the swing shaft 48a to the body-side swing shafts 48b, 48b. In other words, the swing shaft 48a is provided at the upper part of the crankcase 43 above the cylinder axis 44a of the cylinder section 44, and the swing shaft 48a is connected to the body-side swing shafts 48b, 48b by the connecting rod member 48c, so that the unit swing engine 13 is supported on the body frame 12 in a swinging manner.

[0073] The swing shaft 48a and the body-side swing shaft 48b are horizontal shafts extending in the vehicle width direction. The unit-type swing engine 13 is capable of swinging around the swing shaft 48a and the body-side swing shafts 48b, 48b.

[0074] A rear suspension 29 is mounted between the rear end of the unit-type swing motor 13 and the rear of the seat frames 20, 20. Figure 1 ).

[0075] The fuel tank 38 is positioned between the left and right bottom frames 19, 19 in front of the crossbeam 23 and is covered vertically by the foot pedal 11 and the bottom cover 33.

[0076] Figure 5 This is a cross-sectional view of the unit-type oscillating engine 13.

[0077] Reference Figures 2 to 5 The crankcase 43 has a support wall 51 and a support wall 52 perpendicular to the crankshaft 42, and the crankshaft 42 is supported by bearings on the support wall 51 and the support wall 52. A crankshaft chamber 53 is formed between the support wall 51 and the support wall 52.

[0078] The piston 54, which reciprocates within the cylinder 45, is connected to the crankshaft 42 within the crankshaft chamber 53 via the connecting rod 55.

[0079] The crankcase 43 has a generator compartment 56 on the left or right side of the crankcase 53.

[0080] A generator 58, which generates electricity by rotating the crankshaft 42, is provided at one end of the crankshaft 42 that extends into the generator compartment 56. The generator 58 and the crankshaft 42 rotate as a unit. A blower fan 59 is provided on the outer surface of the generator 58. The blower fan 59 is surrounded by a fan shroud 57.

[0081] A radiator 60 is provided on the outside of the air blower 59 for the passage of cooling water from the engine block 40. The radiator 60 is fixed to the outer surface of the generator compartment 56. The radiator 60 is covered from the outside in the vehicle width direction by a radiator cover 61 having a vent 61a.

[0082] A water jacket 40a is provided inside the wall of the cylinder head 46 for cooling water to pass through. A water jacket 40b is provided inside the wall of the cylinder 45 for cooling water to pass through. The water jackets 40a and 40b are connected.

[0083] A valve train 63, which drives an intake valve and an exhaust valve (not shown), is provided on the cylinder head 46. The valve train 63 has a camshaft 64 arranged parallel to the crankshaft 42, and an intake valve and an exhaust valve driven by the camshaft 64. A cover 47 covers the valve train 63.

[0084] The camshaft 64 is driven by the crankshaft 42 via a cam chain 65 that connects the camshaft 64 to the crankshaft 42.

[0085] The cylinder section 44 has a cam chain chamber 66 through which the cam chain 65 passes. The cam chain chamber 66 is disposed across the crankcase 43, the cylinder 45, and the cylinder head 46, and extends axially in the cylinder section 44. The cam chain chamber 66 is located between the crankcase 53 and the generator compartment 56 in the vehicle width direction, and is disposed on one side (right side) of the side wall portion 67R of the cylinder section 44 in the left-right direction (vehicle width direction). The side wall portions 67L and 67R include the side wall portion (side) of the cylinder head 46.

[0086] Spark plug 68 is disposed on the cylinder head 46 on the other side (left side) side wall portion 67L.

[0087] The crankcase 43 integrally has a transmission housing portion 70 extending rearward from a side portion opposite to the generator compartment 56. The transmission housing portion 70 extends from the side portion of the crankcase 53 to the left side of the rear wheel 3.

[0088] The transmission box section 70 is formed as a box with an open outer side in the vehicle width direction, and the open part is closed by the transmission box cover 71.

[0089] The transmission housing cover 71 is fixed to the transmission housing portion 70, thereby forming the arm portion 41 described above.

[0090] In addition, a rearwardly extending auxiliary arm 72 is fixed to the rear of one side (right side) of the crankcase 43 in the vehicle width direction.

[0091] The two ends of the rear wheel axle 3a are supported by the rear end of the arm 41 and the rear end of the auxiliary arm 72, and the rear wheel 3 is disposed between the arm 41 and the auxiliary arm 72.

[0092] The hollow arm 41 is equipped with a belt-type continuously variable transmission 73, a centrifugal clutch mechanism 74, and a reduction mechanism 75 consisting of multiple gears.

[0093] The driving force of the crankshaft 42 is transmitted to the rear wheel 3 via a belt continuously variable transmission 73, a clutch mechanism 74, and a reduction mechanism 75.

[0094] like Figure 3 As shown, the exhaust pipe 77 of the engine body 40 is led out from the lower surface 46a of the cylinder head 46, passes through one side (right side) in the vehicle width direction and extends rearward to the side of the rear wheel 3.

[0095] The intake system of the engine body 40 includes: an air filter box 78; a throttle body 79 connected to an air intake port 46I on the upper surface 46b of the cylinder head 46; and a connecting pipe 80 connecting the air filter box 78 to the throttle body 79. The air filter box 78 is supported by an arm 41.

[0096] When the unit-type swing engine 13 swings via the linkage mechanism 48, the engine body 40, exhaust pipe 77, intake device and radiator 60 swing together as a whole.

[0097] The central support 28, which enables the automatic two-wheeled vehicle 1 to be parked in an upright position, is mounted on the lower surface of the rear part of the crankcase 43. The central support 28 is supported on the crankcase 43 by the central support rotation shaft 28a, and can be rotated about the central support rotation shaft 28a to be in a stowed or parked state.

[0098] Figure 6 This is a right-side view showing the cooling structure of the engine body 40.

[0099] Reference Figures 3 to 6 In the automatic two-wheeled vehicle 1, as a cooling structure for cooling the engine body 40 with cooling water, it includes: a water pump unit 81 for supplying cooling water; a radiator 60; a delivery side hose 82 (radiator hose) through which cooling water flows from the engine body 40 side to the radiator 60; a return side hose 83 through which cooling water returns from the radiator 60 to the engine body 40 side; and a thermal actuator 84 for switching the flow path of the cooling water.

[0100] The water pump unit 81 is installed on one side (right side) of the side wall 67R of the cylinder section 44 in the left-right direction (vehicle width direction). In addition, the radiator 60 is also installed on one side (right side) of the crankcase 43 in the left-right direction (vehicle width direction).

[0101] Through the air supply fan 59 ( Figure 5 The air drawn in through the vent 61a of the radiator cover 61 by the rotation of the radiator 60 undergoes heat exchange with the radiator 60. This promotes the dissipation of cooling water.

[0102] The cylinder section 44 has a cooling water inlet section 85 as an inlet for cooling water flowing into the cylinder section 44; and a cooling water outlet section 86 as an outlet for cooling water flowing out of the cylinder section 44.

[0103] Cooling water inlet 85 and cooling water outlet 86 are located on cylinder head 46.

[0104] Figure 7 This is a right-side view of cylinder head 46. Figure 7 The image shows the state with the pump cover 90 (described later) removed. Figure 8 This is a view of the cylinder head 46 from the rear crankcase 43 side. Figure 9 It is along Figure 3 A cross-sectional view of the IX-IX line.

[0105] Reference Figures 7 to 9 The coolant inlet 85 protrudes downward from the rear of the lower surface 46a of the cylinder head 46. The coolant inlet 85 is formed as a tubular (channel-shaped) portion extending outward in the vehicle width direction from the center of the lower surface 46a toward the water pump unit 81, and has an inlet opening 85a (opening) at its outer end in the vehicle width direction. The coolant inlet 85 communicates with the water jacket 40a of the cylinder head 46. The lower surface 46a is the lower wall surface of the cylinder head 46.

[0106] An exhaust pipe connection portion 46E, which connects to the upstream end of the exhaust pipe 77, is provided at the rear of the lower surface 46a of the cylinder head 46. The exhaust pipe connection portion 46E protrudes downward from the lower surface 46a.

[0107] The base end portion 85b of the cooling water inlet 85 is integrally formed with the outer periphery of the exhaust pipe connection portion 46E. That is, the cooling water inlet 85 and the exhaust pipe connection portion 46E are disposed close to each other. Therefore, the periphery of the exhaust pipe connection portion 46E can be efficiently cooled by using cooling water.

[0108] The exhaust pipe connection 46E and the cooling water inlet 85 are integrally formed with the cylinder head 46 during the casting of the cylinder head 46.

[0109] Figure 10 This is a top view of the cylinder head 46.

[0110] Reference Figure 7 , Figure 8 and Figure 10 The coolant outlet 86 protrudes upward from the rear of the upper surface 46b of the cylinder head 46. The coolant outlet 86 is formed as a tube (channel) extending outward in the vehicle width direction from the center of the upper surface 46b toward the water pump unit 81, and has an outlet opening 86a at its outer end in the vehicle width direction. The coolant outlet 86 communicates with the water jacket 40a of the cylinder head 46.

[0111] An air intake port 46I protruding upward from the upper surface 46b is provided at the rear of the upper surface 46b of the cylinder head 46.

[0112] The base end portion 86b of the cooling water outlet 86 is integrally formed on the outer periphery of the air inlet 46I. That is, the cooling water outlet 86 is disposed close to the air inlet 46I.

[0113] The air intake 46I and the cooling water outlet 86 are integrally formed with the cylinder head 46 during the casting process.

[0114] like Figure 9 and Figure 10 As shown, an actuator 69 for a variable valve timing mechanism of a valve train 63 is provided on a portion of the side wall 67L of the cylinder head 46 of the cylinder section 44. In this variable valve timing mechanism, the operating characteristics of the intake valve and exhaust valve can be changed by the operation of the actuator 69. The actuator 69 is disposed together with the spark plug 68 on the side wall 67L, which is located on the opposite side to the side wall 67R, which is the side where the water pump unit 81 is located.

[0115] like Figure 7 As shown, when viewed from the side facing the side wall portion 67R of the cylinder head 46, the coolant inlet portion 85 protrudes downward from the lower surface 46a of the cylinder head 46, and the coolant outlet portion 86 protrudes upward from the upper surface 46b of the cylinder head 46.

[0116] Additionally, refer to Figure 7 and Figure 8 The coolant inlet 85 and coolant outlet 86, located at the same position as the camshaft chain chamber 66 in the vehicle width direction, are separated vertically from the camshaft chain chamber 66. That is, when viewed from the side facing the side wall portion 67R of the cylinder head 46, the coolant inlet 85 and coolant outlet 86 are outwardly separated from the camshaft chain chamber 66 and do not coincide with it. When viewed from the side, the inlet opening 85a and the outlet opening 86a do not coincide with the camshaft chain chamber 66. Therefore, the coolant inlet 85 and coolant outlet 86 can be provided without affecting the layout of the camshaft chain chamber 66.

[0117] In addition, such as Figure 8 As shown, the inlet opening 85a and the outlet opening 86a are offset from the side wall portion 67R of the cylinder head 46 in the vehicle width direction (towards the cylinder axis 44a).

[0118] like Figure 6 As shown, the water pump unit 81 has an impeller 87 as a rotor and a housing 88 that houses the impeller 87.

[0119] See Figure 5and Figure 6 The impeller 87 has a shaft portion 87a connected to the end of the camshaft 64, and a blade portion 87b disposed on the outer periphery of the shaft portion 87a. The shaft portion 87a is coaxially configured with the camshaft 64, and the shaft portion 87a rotates integrally with the camshaft 64. The blade portion 87b is disposed on the outer side of the side wall portion 67R of the cylinder head 46. That is, the impeller 87 is driven by the crankshaft 42 via the camshaft 64.

[0120] Reference Figure 6 and Figure 7 The housing 88 of the pump unit 81 has a pump housing 89 that supports the impeller 87 and a pump cover 90 that closes the pump housing 89.

[0121] Figure 11 This is a view of the pump cover 90 from the pump housing 89 side. Figure 11 The image shows the state in which a thermal actuator 84 is mounted on the pump housing 90. Figure 12 This is a three-dimensional view of the pump housing 89 as seen from the cylinder head 46 side.

[0122] Reference Figure 6 , Figure 7 and Figure 11 The housing 88 includes: a pump housing 91 for accommodating an impeller 87; a discharge water passage 92 for passing through which cooling water discharged by means of the rotation of the impeller 87 passes; a discharge outlet 93 provided at the end of the discharge water passage 92; a suction inlet 94 for drawing in cooling water; a connecting water passage 95 connected to the cooling water outlet 86 of the cylinder head 46; a bypass water passage 96 connecting the connecting water passage 95 to the thermal actuator 84; and an exhaust passage 97 connecting the pump housing 91 to the bypass water passage 96.

[0123] In the pump housing 91, the discharge water passage 92, the bypass water passage 96, and the exhaust passage 97, cooling water or air passes through the passage formed between the pump housing 89 and the pump cover 90.

[0124] The pump housing 91 is located at the center of the upper and lower parts of the side wall 67R of the cylinder head 46. Figure 7 When viewed from the side, it is housed within the area of ​​the side wall portion 67R. When viewed from the side, the impeller 87 supported by the pump housing 91 is located between the cooling water inlet portion 85 and the cooling water outlet portion 86 in the vertical direction, and is located in front of the cooling water inlet portion 85 and the cooling water outlet portion 86.

[0125] When viewed from the side, the drain water passage 92 extends obliquely downward and rearward from the pump housing 91, and when viewed from the side, its lower end coincides with the inlet opening 85a of the cooling water inlet 85 from the outside. That is, the drain water passage 92 is a protrusion that protrudes downward beyond the lower surface 46a of the cylinder head 46.

[0126] The outlet 93 is a pipe portion provided in the pump housing 89. The outlet 93 extends inward in the vehicle width direction from the lower end of the water discharge passage 92 and is fitted into the inlet opening 85a of the coolant inlet 85. When viewed from the side, the outlet 93 is located below the lower surface 46a of the cylinder head 46.

[0127] When viewed from the side, the bypass water passage 96 extends upward from a position close to the upper part of the rear portion of the pump housing 91, and when viewed from the side, the upper end of the bypass water passage 96 coincides with the outlet opening 86a of the coolant outlet 86 from the outside. That is, the bypass water passage 96 is a protrusion that protrudes upward from the upper surface 46b of the cylinder head 46. The bypass water passage 96 is not directly connected to the pump housing 91.

[0128] The connecting water passage 95 is a pipe section provided in the pump housing 89. The connecting water passage 95 extends inward in the vehicle width direction from the upper end of the bypass water passage 96 and is fitted into the outlet opening 86a of the coolant outlet 86. When viewed from the side, the connecting water passage 95 is located above the upper surface 46b of the cylinder head 46.

[0129] The pump housing 89 has a cylindrical sensor mounting portion 98 extending forward from the water connection portion 95. A water temperature sensor 99, which measures the temperature of the cooling water, is inserted from the front and fixed to the sensor mounting portion 98. When viewed from the side, the water temperature sensor 99 is configured to coincide with the cylinder head 46.

[0130] Reference Figure 11 The suction port 94 is a cylindrical part located at the rear of the pump cover 90. The suction port 94 makes the rear of the pump housing 91 open at the rear.

[0131] In addition, the pump cover 90 has a bypass cylinder 96a that opens at the rear at the lower end of the bypass water passage 96.

[0132] The intake port 94 and the bypass cylinder 96a are arranged parallel to each other and extend in the front-rear direction.

[0133] The thermal actuator unit 84 is mounted from the rear of the pump housing 90 to the suction port 94 and the bypass cylinder portion 96a. That is, the thermal actuator unit 84 is fixed to the pump housing 90.

[0134] Furthermore, the pump cover 90 has a tubular hose connection 100 extending rearward and upward from the upper end of the bypass water passage 96.

[0135] The housing 88 of the water pump unit 81 is fastened to the cylinder head 46 by a plurality of housing fixing bolts 101 that extend from the outside of the pump housing 91 in the vehicle width direction. At the portion of the housing fixing bolts 101, the pump cover 90 and the pump housing 89 are together fixed to the cylinder head 46.

[0136] In addition, the pump cover 90 is fastened to the pump housing 89 by pump cover fixing bolts 102 that penetrate from the outside of the vehicle width direction and pass through the outer periphery of the discharge water passage section 92 and the bypass water passage section 96.

[0137] Reference Figure 7 and Figure 11 The thermal actuator unit 84 includes: a vertically extending cylindrical portion 84a; a bypass connecting pipe 84b and an intake connecting pipe 84c extending forward from the cylindrical portion 84a; and a hose connecting pipe 84d disposed at the lower end. The hose connecting pipe 84d is connected to the downstream end of the return side hose 83.

[0138] In addition, the thermal actuator unit 84 has: an actuator internal bypass water passage 84e (bypass water passage) that connects the bypass connection pipe 84b to the suction inlet connection pipe 84c; and an actuator internal return water passage 84f (water passage through which cooling water in the normal path passes) that connects the hose connection pipe 84d to the suction inlet connection pipe 84c.

[0139] The return water path 84f and the bypass water path 84e inside the actuator are coaxially arranged and interconnected.

[0140] The cylindrical section 84a has a straight switching channel 84g formed by the return water path 84f inside the actuator and the bypass water path 84e inside the actuator.

[0141] A bypass connection pipe 84b is inserted into the bypass cylinder 96a, and a suction inlet connection pipe 84c is inserted into the suction inlet 94, thereby connecting the thermal actuator unit 84 to the pump housing 90. That is, the thermal actuator unit 84 is connected to the water pump unit 81 through the pump housing 90.

[0142] The switching channel 84g is equipped with a switching valve 84h consisting of a thermal actuator (thermostat). Here, the aforementioned thermal actuator is a component that expands and contracts with temperature changes, for example, it contains wax that expands with temperature changes.

[0143] The switching valve 84h moves within the switching channel 84g according to the temperature of the cooling water. Specifically, the switching valve 84h is in either a "normal position" or a "bypass position". The "normal position" is when the return hose 83 is connected to the suction port 94 and the connection between the bypass water passage 96 and the suction port 94 is cut off. The "bypass position" is when the bypass water passage 96 is connected to the suction port 94 and the connection between the return hose 83 and the suction port 94 is cut off.

[0144] like Figure 6 As shown, the radiator 60 is positioned behind the water pump unit 81 and on the outside of the crankcase 43.

[0145] The radiator 60 includes: an upper box 105 disposed at the upper end of the radiator 60; a lower box 106 disposed at the lower end of the radiator 60; and a radiator core 107 connecting the upper box 105 and the lower box 106 vertically.

[0146] Cooling water is stored in the upper box 105 and the lower box 106. The radiator core 107 is formed in the shape of a plate and has a plurality of cooling water pipes that connect the upper box 105 and the lower box 106, and a plurality of cooling fins disposed around the cooling water pipes.

[0147] The radiator core 107 is roughly rectangular when viewed from the side. The radiator 60 is oriented with the thickness of the radiator core 107 pointing towards the width of the vehicle.

[0148] The radiator 60 has a filler port 108 at its upper front portion, protruding upward from the front of the upper surface of the upper housing 105. Cooling water can be replenished through the filler port 108. The filler port 108 is closed by the radiator cover 109. The upper housing 105 has an upper connecting pipe 110 extending forward from a position below and in front of the filler port 108.

[0149] The downstream end of the delivery hose 82 (radiator inflow hose) is connected to the upper connecting pipe 110. The upstream end of the delivery hose 82 is connected to the hose connection portion 100 of the pump cover 90. When viewed from the side, the delivery hose 82 extends from the hose connection portion 100 with a lower front and higher rear to the upper connecting pipe 110.

[0150] The lower housing 106 has a lower connecting pipe 111 extending obliquely forward and upward from the lower part of the front surface. The upstream end of the return side hose 83 (radiator outlet hose) is connected to the lower connecting pipe 111. The downstream end of the return side hose 83 is connected to the hose connecting pipe 84d of the thermal actuator unit 84. Figure 11 )connect.

[0151] When viewed from the side, the return hose 83 extends from the lower connecting pipe 111 at a higher front and lower rear to the hose connecting pipe 84d.

[0152] Here, refer to Figure 6 , Figure 7 and Figure 11 This indicates the flow of cooling water. Figure 7 and Figure 11 In the diagram, the normal path N represents the flow of cooling water in the "normal position" case, and the bypass path B represents the flow of cooling water in the "bypass position" case.

[0153] When the switching valve 84h of the thermal actuator unit 84 is in the "normal position", the cooling water path is the normal path that passes through the water pump unit 81, cylinder head 46, cooling water outlet 86, radiator 60 and thermal actuator unit 84 in sequence and returns to the water pump unit 81.

[0154] In detail, in the normal path, the cooling water pressurized and delivered by the impeller 87 flows from the discharge water passage 92 through the discharge port 93 and directly into the cooling water inlet 85 of the cylinder head 46 from the water pump unit 81.

[0155] Cooling water flowing into the cooling water inlet 85 passes through the water jackets 40a and 40b and moves upward inside the cylinder head 46, flowing from the cooling water outlet 86 to the outside of the cylinder head 46.

[0156] Cooling water from the cooling water outlet 86 flows to the connecting water passage 95 of the water pump unit 81, passes through the delivery hose 82 and flows into the upper box 105 of the radiator 60, passes through the radiator core 107 and then flows into the lower box 106.

[0157] Cooling water in the lower tank 106 flows to the thermal actuator unit 84 through the return hose 83, passes through the return water passage 84f and the suction inlet connecting pipe 84c in the actuator, and returns to the pump housing 91 from the suction inlet 94.

[0158] In the normal path, the radiator 60 is used to dissipate heat from the cooling water, thereby efficiently cooling the engine block 40.

[0159] When the switching valve 84h of the thermal actuator unit 84 is in the "bypass position", the path of the cooling water is a bypass path that passes through the water pump unit 81, cylinder head 46, cooling water outlet 86 and thermal actuator unit 84 in sequence and returns to the water pump unit 81.

[0160] In detail, within the bypass path, the cooling water pressurized and delivered by the impeller 87 flows directly from the water pump unit 81 into the cooling water inlet 85 of the cylinder head 46 through the outlet 93 from the outlet water passage 92.

[0161] Cooling water flowing into the cooling water inlet 85 passes through the water jackets 40a and 40b and moves upward inside the cylinder head 46, and flows out of the cooling water outlet 86 to the outside of the cylinder head 46.

[0162] Cooling water from the cooling water outlet section 86 flows from the connecting water passage section 95 of the water pump unit 81 to the bypass water passage section 96, and returns to the pump housing section 91 from the suction port 94 through the bypass connecting pipe 84, the bypass water passage 84e in the actuator and the suction port connecting pipe 84c.

[0163] In the bypass path, the cooling water flowing from the cooling water outlet 86 bypasses the radiator 60 and returns to the water pump unit 81. When the cooling water temperature is lower than the specified temperature and the engine body 40 needs to be warmed up, the switching valve 84h is in the "bypass position".

[0164] In this way, when warm-up is required, the cooling water bypasses the radiator 60, thus enabling the cooling water temperature to rise rapidly and efficiently warm up the machine.

[0165] Air accumulated in the pump housing 91 flows upward from the upper part of the pump housing 91 through the exhaust passage 97 and into the bypass water passage 96. Thereafter, it flows through the delivery hose 82 to the upper box 105 of the radiator 60. Therefore, air can be efficiently discharged from the supply port 108 of the radiator 60.

[0166] Figure 13 This is a view of the unit-type oscillating engine 13 and its peripheral portion from below.

[0167] Reference Figure 2 , Figure 3 and Figure 13 The cylinder section 44 extends forward from the front surface of the crankcase 43 and is located between the upright sections 21, 21 of the left and right seat frames 20, 20.

[0168] An oil pan 43a is provided at the lower part of the crankcase 43 to store oil from the engine body 40. The oil pan 43a protrudes downward relative to the cylinder section 44 and the exhaust pipe connection section 46E.

[0169] The front end 43b of the crankcase 43 is the front end of the oil pan section 43a. The lower surface 43c of the crankcase 43 is the lower surface of the oil pan section 43a, located below the lower end of the radiator 60.

[0170] like Figure 13 As shown, the exhaust pipe connection 46E of the cylinder head 46 is located within the width range of the rear wheel 3 in the vehicle width direction, and is located at the center in the vehicle width direction. The centerline C in the vehicle width direction passes through the center of the rear wheel 3.

[0171] Reference Figure 2 , Figure 3 and Figure 13 The exhaust pipe 77 has: an upstream exhaust pipe 120 connected to the exhaust pipe connection portion 46E of the cylinder head 46; a catalyst device 121 connected to the downstream end of the upstream exhaust pipe 120; and a downstream exhaust pipe 122 connected to the downstream end of the catalyst device 121.

[0172] The catalyst device 121 is located between the upstream exhaust pipe 120 and the downstream exhaust pipe 122 in the direction of exhaust flow, and is positioned in the middle of the exhaust pipe 77.

[0173] The downstream exhaust pipe 122 has an exhaust pipe section 123 extending rearward from the catalyst device 121, and a muffler section 124 connected to the downstream end of the exhaust pipe section 123.

[0174] The muffler section 124 is positioned on one side (right side) of the vehicle width direction relative to the rear wheel 3. That is, the muffler section 124 is positioned on one side of the vehicle width direction relative to the rear wheel 3 located on the center line C in the vehicle width direction, while the arm section 41 is positioned on the other side (left side) of the vehicle width direction relative to the rear wheel 3.

[0175] Figure 14 This is a top view of the exhaust pipe 77 from above. Figure 15 This is a three-dimensional view of the exhaust pipe 77 viewed from the right side.

[0176] Reference Figures 13 to 15 The upstream exhaust pipe 120 has: a lower extension 125 extending downward from the exhaust pipe connection 46E in the forward direction of the catalyst device 121; a lateral extension 126 extending from the lower end of the lower extension 125 outward in the vehicle width direction to the side opposite to the muffler section 124 (the other side in the vehicle width direction); and a curved section 127 extending rearward from the outer end of the lateral extension 126 and turning back in a U-shape in the vehicle width direction.

[0177] The outer surface 127a of the curved portion 127 is located inside the seat frame 20, 20, the raised portions 21, 21.

[0178] Catalyst device 121 has a cylindrical outer cylinder 121a that is longer in the vehicle width direction, and a cylindrical catalyst carrier 121e housed inside the outer cylinder 121a (see reference). Figure 9 , Figure 13 The catalyst support is a honeycomb-shaped porous structure with multiple fine pores extending along its axis. Platinum, rhodium, and palladium are mounted on the catalyst support as catalysts for decomposing the components of the exhaust gas.

[0179] The diameter of the catalyst device 121 is larger than the diameter of the exhaust pipe portion 123 of the upstream exhaust pipe 120 and the downstream exhaust pipe 122. The catalyst device 121 is configured such that its length direction is oriented towards the vehicle width direction.

[0180] The catalyst device 121 and the upstream exhaust pipe 120 are disposed within a space R, which is located in front of the front end 43b of the crankcase 43 and below the cylinder section 44. The catalyst device 121 is disposed approximately horizontally within the space R with its axis 121b pointing in the vehicle width direction, i.e., when viewed from below, the axis 121b is approximately perpendicular to the centerline C in the vehicle width direction. Furthermore, the axis 121b of the catalyst device 121 pointing in the length direction is parallel to the crankshaft 42. Moreover, the axis 121b of the catalyst device 121 does not necessarily have to be completely parallel to the crankshaft 42; as long as the length direction of the catalyst device 121 points in the vehicle width direction, it can also be disposed at a slight angle relative to the crankshaft 42.

[0181] The upstream end of the catalyst device 121, located at the outer end in the vehicle width direction, is connected to the downstream end of the curved portion 127.

[0182] In detail, the catalyst device 121 is positioned below the cylinder 45, in front of the front end 43b of the crankcase 43 and behind the exhaust pipe connection 46E of the cylinder head 46. In a side view, the catalyst device 121 is located behind the upstream exhaust pipe 120 and in front of the front end 43b of the crankcase 43.

[0183] Furthermore, the catalyst device 121 is located above the front end of the lower surface 43c of the crankcase 43 and below the cylinder 45. Moreover, when viewed from below, the catalyst device 121 is located between the left and right upright portions 21, 21 of the seat frames 20, 20. Furthermore, as... Figure 2 As shown, the catalyst device 121 is positioned above the imaginary straight line U1, which connects the lower surface of the rear of the bottom cover 33 to the lower surface 43c of the crankcase 43.

[0184] The catalyst device 121 is offset in the vehicle width direction as follows: the center 121c of the catalyst device 121 in the vehicle width direction (in Figure 13 (As shown in the diagram) The centerline C in the width direction relative to the automatic two-wheeled vehicle 1 is located on one side in the width direction, that is, on the side where the muffler section 124 is located. Here, the center 121c in the width direction of the catalyst device 121 is the center in the length direction of the catalyst device 121.

[0185] like Figure 14As shown, a constricted portion (recess) 127c, recessed inwards towards the inner side of the bend 127, is provided on the rear surface of the downstream end of the bend 127 of the upstream exhaust pipe 120. The imaginary axis 127b of the bend 127, passing through its center, is offset radially outwards from the line passing through the radial center of the catalyst device 121 (the axis of the catalyst device 121) by a distance D. Therefore, even when the bend 127 is provided upstream of the catalyst device 121, the exhaust gas can still contact the center of the catalyst device 121, resulting in good exhaust gas contact and suppressing localized deterioration of the catalyst device 121.

[0186] In addition, such as Figure 3 As shown in the side view, the catalyst device 121 is disposed in the region between imaginary line L1 and imaginary line L2. Imaginary line L1 connects the vehicle-side swing shafts 48b, 48b of the linkage mechanism 48 to the front end 43b of the crankcase 43, and imaginary line L2 connects the vehicle-side swing shafts 48b, 48b to the exhaust pipe connection 46E. Here, imaginary line L2 is configured to pass through the front end of the exhaust pipe connection 46E.

[0187] Furthermore, from another perspective, the catalyst device 121 is positioned in front of the front end 43b of the crankcase 43, such that at least a portion of it overlaps with the cylinder 45 from below when viewed from above. When viewed from above, the catalyst device 121 can be entirely overlapped with the cylinder 45 from below; however, the front end or the outer end in the vehicle width direction can also be positioned further outward than the cylinder 45.

[0188] In this first embodiment, the connecting rod mechanism 48 is positioned above the crankcase 43, thus ensuring space below the cylinder 45 and in the area between imaginary lines L1 and L2, allowing the catalyst device 121 to be positioned within this space. Therefore, the catalyst device 121 can be compactly positioned so that it does not collide with other components surrounding it.

[0189] Specifically, the catalyst device 121 is disposed between the exhaust pipe connection 46E of the cylinder head 46 and the front end 43b of the crankcase 43. Therefore, while ensuring the placement space of the upstream exhaust pipe 120 extending from the exhaust pipe connection 46E, the space between the upstream exhaust pipe 120 and the front end 43b can be effectively utilized, thereby compactly arranging the catalyst device 121.

[0190] Furthermore, the upstream exhaust pipe 120 has a lateral extension 126 and a bend 127, and extends in the vehicle width direction to the side opposite to the catalyst device 124 and then turns back to connect with the catalyst device 121. Therefore, the length of the upstream exhaust pipe 120 can be ensured to be longer, and the upstream exhaust pipe 120 can be increased according to the required characteristics of the engine body 40.

[0191] Furthermore, the center 121c of the catalyst device 121 in the vehicle width direction is offset towards the muffler section 124 compared to the center line C in the vehicle width direction of the automatic two-wheeled vehicle 1, thus ensuring a longer pipe length for the upstream exhaust pipe 120.

[0192] The exhaust pipe section 123 of the downstream exhaust pipe 122 has: a bent section 128 that bends rearward from the downstream end of the catalyst device 121; and a rearward extension section 129 that extends rearward from the rear end of the bent section 128.

[0193] The muffler section 124 is connected to the rear end of the rear extension section 129.

[0194] The bend 128 is located in front of the front end 43b of the crankcase 43, below the left-side upright portion 21. The front end of the bend 128 is the front end 122a of the downstream exhaust pipe 122. This front end 122a is the portion that connects to the downstream end of the catalyst device 121 and is located in front of and below the front end of the radiator 60.

[0195] The rear extension 129 extends rearward beyond the outer side of the oil pan portion 43a of the crankcase 43. The rear extension 129 passes below the radiator 60, and when viewed from below, a portion of the rear extension 129 overlaps with the radiator 60 from below.

[0196] The muffler section 124, which serves as a muffler, is located behind the radiator 60 on the right side of the rear wheel 3 and extends in the longitudinal direction. The muffler section 124 is fixed to the auxiliary arm 72. The muffler section 124 is a pipe with a diameter larger than that of the exhaust pipe section 123, and has multiple expansion chambers inside that are divided by baffles.

[0197] like Figure 1 As shown, the lower end 28b of the central support 28, when in its accommodated state, serves as the reference point for the lowest ground clearance of the automatic two-wheeled vehicle 1. The lower end 28b is located on the left and right sides relative to the rear wheels 3, and is the part that initially contacts the road surface when the automatic two-wheeled vehicle 1 tilts to the left or right.

[0198] The catalyst device 121 is positioned above the lower end 28b of the central support 28. Therefore, even with a structure that positions the catalyst device 121 below the cylinder 45, the catalyst device 121 can be positioned sufficiently high relative to the road surface.

[0199] like Figure 2 and Figure 13 As shown, the crossbeam 23 and the fuel tank 38 are positioned at approximately the same height as the upstream exhaust pipe 120 and the catalyst device 121, in front of them. That is, when viewed from the front, the crossbeam 23 and the fuel tank 38 coincide with the upstream exhaust pipe 120 and the catalyst device 121 from the front. Therefore, the crossbeam 23 and the fuel tank 38 effectively protect the upstream exhaust pipe 120 and the catalyst device 121.

[0200] Furthermore, the catalyst device 121 is located at the outer end 60b of the radiator 60 in the vehicle width direction. Figure 13 (The location is on the inside side in the direction of vehicle width.)

[0201] like Figure 3 and Figure 9 As shown, the coolant inlet 85 on the lower surface 46a of the cylinder head 46 is positioned above the catalyst device 121 and is offset (staggered) forward relative to the catalyst device 121. Therefore, even with the structure of providing the coolant inlet 85 on the lower surface 46a of the cylinder head 46, the catalyst device 121 does not easily obstruct the configuration of the coolant inlet 85.

[0202] Figure 16 This is a right-side view of the periphery of the radiator 60 and the linkage mechanism 48. Figure 17 This is a view of the periphery of the radiator 60 and the linkage mechanism 48 from above. Here, the linkage mechanism 48 is arranged in a roughly symmetrical manner. Figure 16 Only the right side of linkage 48 is shown in the image.

[0203] Reference Figure 16 and Figure 17 The linkage component 48c of the linkage mechanism 48 has: a first pivot portion 130, 130 (outer end) supported by the vehicle body side swing shafts 48b, 48b; a rod-shaped left and right connecting portion 131 connecting the rear portions of the first pivot portions 130, 130 in the vehicle width direction; and a second pivot portion 132 extending downward from the left and right connecting portion 131 and supported by the swing shaft 48a.

[0204] Reference Figure 10 A swing shaft connecting part 43d is provided on the upper part of the front end of the crankcase 43 to support both ends of the swing shaft 48a. The second pivot part 132 is located between the left and right first pivot parts 130 and 130 in the vehicle width direction, and its lower end is connected to the swing shaft 48a.

[0205] When viewed from the side, the swing shaft 48a is located below and behind the swing shafts 48b and 48b on the side of the vehicle body, and is located on the inside side of the vehicle width direction compared to the left and right swing shafts 48b and 48b on the side of the vehicle body.

[0206] Reference Figure 16 When viewed from the side, the radiator 60 has a roughly rectangular radiator core 107 whose upper end is connected to the upper box 105, while the lower edge of the radiator core 107 is connected to the lower box 106.

[0207] The radiator 60 is configured with its leading edge 107a (the leading edge of the radiator) tilted backward relative to the vertical line when viewed from the side. Therefore, when viewed from the side, the trailing edge 107b of the radiator core 107 is tilted backward in the same way as the leading edge 107a, and the upper casing 105 and the lower casing 106 are configured with the front higher than the rear.

[0208] When viewed from the side, the catalyst device 121 is positioned below the front end of the lower housing 106. More specifically, when viewed from the side, the catalyst device 121 is positioned below the lower connecting pipe 111 at the front end of the lower housing 106. Therefore, by utilizing the space below the front end of the lower housing 106, which is positioned with a higher front and lower rear, the catalyst device 121 can be efficiently positioned.

[0209] When viewed from the side, the lower box 106 is located behind the catalyst device 121 and is positioned vertically between the catalyst device 121 and the cylinder section 44.

[0210] like Figure 16 As shown, the uppermost end 121d of the catalyst device 121 is located above the lowermost end 60a of the radiator 60. The uppermost end 121d is the upper surface of the outer cylinder 121a. The lowermost end 60a is the lowermost end of the lower casing 106. Furthermore, the uppermost end 121d of the catalyst device 121 is located above the rear end of the lower casing 106 of the radiator 60.

[0211] In this way, by arranging at least a portion of the catalyst device 121 to overlap with the lower part of the radiator 60 in the vertical direction, the catalyst device 121 and the radiator 60 can be compactly arranged in the vertical direction.

[0212] When viewed from the side, the swing shaft 48a of the linkage mechanism 48 is positioned in front of the front edge 107a, below the upper end 107c of the front edge 107a of the radiator core 107.

[0213] In detail, the swing shaft 48a is located in front of the upper part of the leading edge 107a and is located behind the lower end 107d of the leading edge 107a.

[0214] That is, the swing shaft 48a is positioned in the space secured in front of the upper part of the radiator core 107 by tilting the radiator core 107 backward.

[0215] In addition, the swing shaft 48a is located below the delivery side hose 82 and behind the erected part 21.

[0216] The swing shaft 48a is not covered by the radiator core 107 because it is offset forward from the front edge 107a of the radiator core 107, but is exposed on the outside. Therefore, the swing shaft 48a can be accessed from the outside even without removing the radiator 60, making maintenance and assembly of the swing shaft 48a easier. Furthermore, the swing shaft 48a is located below the upper end 107c of the front edge 107a of the radiator core 107, thus reducing the vertical length of the swing shaft connection portion 43d of the crankcase 43 and making the crankcase 43 more compact in the vertical direction. In addition, the swing shaft 48a is positioned so that, when viewed from the side, it does not coincide with the pair of left and right support frames 25, 25 extending rearward from the upright portions 21, 21 of the body frame 12.

[0217] like Figure 16 As shown, the radiator 60 is offset (staggered) from the crankshaft 42 such that the center 107e of the radiator core 107 is located behind and below the rotation center 42a of the crankshaft 42 when viewed from the side.

[0218] The rotation center 42a of crankshaft 42 and the blower fan 59 ( Figure 5 The rotation center of the heat sink 60 is aligned with that of the fan 59. That is, the heat sink 60 is arranged such that the center 107e of the heat sink core 107 is located behind the rotation center of the fan 59. Therefore, space can be ensured in front of the front edge 107a of the heat sink core 107, and the swing shaft 48a can be arranged in front of the front edge 107a of the heat sink core 107.

[0219] When viewed from the side, the upper connecting pipe 110 of the radiator 60 is located directly above the swing shaft 48a.

[0220] like Figure 17 As shown, the upper connecting pipe 110 extends diagonally from the upper box 105 in the width direction of the vehicle and towards the front.

[0221] Furthermore, the upper connecting pipe 110 is located inside the vehicle width direction of the first pivot portion 130, which is the outer end of the linkage mechanism 48 in the vehicle width direction. Therefore, the upper connecting pipe 110 can be protected by the first pivot portion 130.

[0222] The conveying hose 82, which is connected to the upper connecting pipe 110, passes inside the upright part 21 in the vehicle width direction, and when viewed from the side, it passes between the swing shaft 48a and the vehicle body side swing shaft 48b and is positioned forward. Therefore, the conveying hose 82 can be configured compactly.

[0223] Reference Figures 13 to 16 An upstream exhaust gas sensor 140 is installed in the upstream exhaust pipe 120 to detect the exhaust gas flowing in the upstream exhaust pipe 120.

[0224] In addition, a downstream exhaust gas sensor 141 for detecting the exhaust gas flowing in the downstream exhaust pipe 122 is provided in the downstream exhaust pipe 122.

[0225] Here, the upstream exhaust gas sensor 140 and the downstream exhaust gas sensor 141 are oxygen sensors that detect the oxygen concentration in the exhaust gas.

[0226] Alternatively, the upstream exhaust gas sensor 140 and the downstream exhaust gas sensor 141 can also be, for example, temperature sensors that detect the temperature of the exhaust gas.

[0227] The upstream exhaust gas sensor 140 is formed in the shape of a rod, with a detection part 140a for detecting oxygen at one end in the axial direction and a terminal part 140b at the other end in the axial direction. The information detected by the detection part 140a is output through a wire harness 140c extending from the terminal part 140b.

[0228] The downstream exhaust gas sensor 141 is formed in the shape of a rod, with a detection part 141a for detecting oxygen at one end in the axial direction and a terminal part 141b at the other end in the axial direction. The information detected by the detection part 141a is output through a wire harness 141c extending from the terminal part 141b.

[0229] Wiring harnesses 140c and 141c are connected to an electronic control unit (not shown) that controls the unit-type oscillating motor 13 of the automatic two-wheeled vehicle 1.

[0230] The upstream exhaust gas sensor 140 is installed on the lower extension 125 of the upstream exhaust pipe 120.

[0231] In detail, the upstream exhaust gas sensor 140 is installed obliquely upward and forward from the front surface of the lower extension 125 and outward in the vehicle width direction. The upstream exhaust gas sensor 140 is installed on the side opposite to the side of the curved portion 127 in the vehicle width direction.

[0232] The upstream exhaust gas sensor 140 is inserted obliquely from the front top and the outside in the vehicle width direction into the front surface of the lower extension 125 and thus fixed to the lower extension 125.

[0233] The upstream exhaust gas sensor 140 is fixed to the lower extension 125 with the detection section 140a as its lower end. The terminal section 140b becomes the upper end of the upstream exhaust gas sensor 140.

[0234] The detection part 140a is located inside the upstream exhaust pipe 120, and the terminal part 140b is exposed on the outside of the upstream exhaust pipe 120.

[0235] The upstream exhaust gas sensor 140 is configured to run along the direction of the exhaust gas flow passing through the lower extension 125. More specifically, the upstream exhaust gas sensor 140 is configured such that the axis 140d of the detection unit 140a intersects at an acute angle with the flow direction of the exhaust gas in the portion where the detection unit 140a is located.

[0236] In the lower extension 125, the exhaust gas flows downwards, so the upstream exhaust gas sensor 140 is configured with its end detection section 140a pointing downwards. This suppresses turbulence in the exhaust gas flow around the detection section 140a, thus enabling efficient detection of oxygen concentration using the detection section 140a.

[0237] The upstream exhaust gas sensor 140 is located in front of the catalyst unit 121, in the lower extension 125. When viewed from below, the upstream exhaust gas sensor 140 coincides with the cylinder section 44 and is located below the cylinder section 44.

[0238] The upstream exhaust gas sensor 140 is inserted from the front into the lower extension 125 located in front of the catalyst unit 121, so that it is not easy to interfere with the catalyst unit 121 when the upstream exhaust gas sensor 140 is inserted. Therefore, the upstream exhaust gas sensor 140 can be easily installed in the lower extension 125.

[0239] When viewed from above, the upstream exhaust gas sensor 140 is located between the upright portions 21, 21 of the seat frames 20, 20. Furthermore, a crossbeam 23 and a fuel tank 38 are arranged on the front of the upstream exhaust gas sensor 140. Therefore, the upstream exhaust gas sensor 140 can be protected by the upright portions 21, 21, the crossbeam 23, and the fuel tank 38.

[0240] In addition, such as Figure 2 As shown, the upstream exhaust gas sensor 140 is covered from the outside by the lower end 34a of the side cover 34.

[0241] like Figure 13 As shown, the bottom cover 33 has a notch 33a at its rear end, in front of the upstream exhaust pipe 120, formed by cutting it out to the forward side. A portion of the crossbeam 23 and the fuel tank 38 are exposed downwards from the notch 33a.

[0242] The wiring harness 140c of the upstream exhaust gas sensor 140 is led forward and outward in the vehicle width direction from the terminal portion 140b. The notch portion 33a is missing forward in a manner that avoids the wiring harness 140c of the upstream exhaust gas sensor 140.

[0243] Reference Figures 13 to 16 The downstream exhaust gas sensor 141 is disposed on the rear extension 129 of the exhaust pipe portion 123 of the downstream exhaust pipe 122. In detail, the rear part of the rear extension 129 becomes an inclined portion 129a that is inclined from the front to the rear when viewed from the side, and the downstream exhaust gas sensor 141 is mounted on the upper surface of the inclined portion 129a.

[0244] When viewed from the side, the downstream exhaust gas sensor 141 is installed obliquely upward from the upper surface of the inclined portion 129a. The downstream exhaust gas sensor 141 is inserted obliquely from the front and upper surface into the upper surface of the inclined portion 129a, which is lower at the front and higher at the rear, and is thus fixed to the inclined portion 129a.

[0245] The downstream exhaust gas sensor 141 is fixed to the inclined portion 129a of the downstream exhaust pipe 122 with the detection portion 141a as its lower end. The terminal portion 141b becomes the upper end of the downstream exhaust gas sensor 141.

[0246] The detection part 141a is located inside the downstream exhaust pipe 122, and the terminal part 141b is exposed on the outside of the downstream exhaust pipe 122.

[0247] The downstream exhaust gas sensor 141 is configured along the direction of the exhaust gas flow passing through the inclined section 129a. More specifically, the downstream exhaust gas sensor 141 is configured such that the axis 141d of the detection section 141a intersects at an acute angle with the flow direction of the exhaust gas in the portion where the detection section 141a is configured.

[0248] In the inclined section 129a, the exhaust gas flows backward and upward, so the downstream exhaust gas sensor 141 is configured with its end detection section 141a pointing backward. As a result, turbulence in the flow of exhaust gas around the detection section 141a can be suppressed, thus enabling efficient detection of oxygen concentration using the detection section 141a.

[0249] like Figure 16 As shown, the downstream exhaust gas sensor 141, when viewed from the side, is positioned rearward from the rear edge 107b of the radiator core 107. Specifically, the downstream exhaust gas sensor 141 is located vertically between the upper and lower ends of the rear edge 107b of the radiator core 107. The downstream exhaust gas sensor 141 coincides with the radiator core 107 in the vertical direction.

[0250] In addition, the downstream exhaust gas sensor 141 is located in the vehicle longitudinal direction between the rear edge 107b of the radiator core 107 and the front wall 124a of the front end of the muffler section 124.

[0251] When viewed from the side, the catalyst device 121 is located in front of and below the lower housing 106 of the radiator 60, positioned forward relative to the radiator 60. The upper part of the catalyst device 121 coincides with the lower housing 106 in the vertical direction.

[0252] That is, the catalyst device 121 and the downstream exhaust gas sensor 141 are disposed apart from the radiator 60 in the front-rear direction. Therefore, the catalyst device 121, the radiator 60 and the downstream exhaust gas sensor 141 can be compactly arranged in the vertical direction.

[0253] An oil filler port 150 for injecting lubricating oil into the engine block 40 is provided at the rear end of the crankcase 43. The oil filler port 150 is sealed by a cover 151. The cover 151 has a rod-shaped oil level gauge (not shown) that extends into the oil filler port 150 to detect the oil level.

[0254] Figure 18 This is a three-dimensional view of the periphery of the oil inlet 150 as viewed from above.

[0255] Reference Figure 16 and Figure 18 The oil filler port 150 is located behind the rear edge 107b of the radiator core 107, and between the rear edge 107b and the front edge 72a of the auxiliary arm 72. Furthermore, the oil filler port 150 is located between the upper and lower ends of the rear edge 107b of the radiator core 107 in the vertical direction. The oil filler port 150 and the cover 151 are located inside the inclined portion 129a in the vehicle width direction.

[0256] The oil filler port 150 is formed as a cylindrical shape extending rearward and upward and outward in the vehicle width direction, and has an opening on its upper surface. The cover 151 is screwed into the threaded portion provided on the inner circumference of the upper end of the oil filler port 150 to close the opening of the oil filler port 150.

[0257] The axis 151a of the cover 151 extends with a lower front and higher rear when viewed from the side.

[0258] The downstream exhaust gas sensor 141 is located directly below the oil filler port 150 and the cap 151. The axis 141d of the detection part 141a of the downstream exhaust gas sensor 141 extends with a higher front and lower rear when viewed from the side, and is approximately perpendicular to the axis 151a of the oil filler port 150 and the cap 151.

[0259] In this way, the axis 141d of the downstream exhaust gas sensor 141 located below the cover 151 intersects with the axis 151a of the cover 151, so interference is less likely to occur when the cover 151 is loaded or unloaded, thus improving the efficiency of operation.

[0260] In the exhaust pipe 77, an upstream exhaust gas sensor 140 is installed upstream of the catalyst device 121, and a downstream exhaust gas sensor 141 is installed downstream of the catalyst device 121. Thus, the oxygen concentration of the exhaust gas before and after passing through the catalyst device 121 can be detected using the upstream and downstream exhaust gas sensors 140 and 141. Therefore, the purification performance of the exhaust gas from the catalyst device 121 can be monitored.

[0261] As described above, according to the first embodiment of the present invention, the single-unit oscillating engine 13 includes: a cylinder section 44 having a cylinder 45 and a cylinder head 46; and a water pump unit 81 mounted on a side wall portion 67R of the cylinder head 46. The cylinder section 44 has a cooling water inlet portion 85 directly connected to the outlet 93 of the water pump unit 81. When viewed from the side facing the side wall portion 67R of the cylinder head 46, the cooling water inlet portion 85 protrudes outward from the lower surface 46a, which is a wall surface of the cylinder section 44. With this structure, the outlet 93 of the water pump unit 81 mounted on the side wall portion 67R of the cylinder head 46 is directly connected to the cooling water inlet portion 85 of the cylinder section 44. Therefore, a hose-like component connecting the water pump unit 81 to the cooling water inlet portion 85 is not required, simplifying the construction of the cooling passage. Furthermore, when viewed from the side facing the side wall portion 67R of the cylinder head 46, the coolant inlet portion 85 protrudes outward from the lower surface 46a of the cylinder portion 44. Therefore, the coolant inlet portion 85 can be provided without complicating the structure of the cylinder head 46 which is located inward from the lower surface 46a, thus simplifying the structure of the cylinder head 46.

[0262] Furthermore, the cylinder section 44 has a cooling water outlet section 86 that serves as an outlet for cooling water to flow out from the cylinder section 44. When viewed from the side facing the side wall section 67R of the cylinder head 46, the cooling water outlet section 86 protrudes outward from the upper surface 46b, which is the wall surface of the cylinder head 46. With this structure, the cooling water outlet section 86 can be provided without complicating the construction of the cylinder head 46 that is located inward from the upper surface 46b, thus simplifying the construction of the cylinder head 46.

[0263] Furthermore, the cylinder section 44 includes: a cam chain 65 that transmits the rotation of the crankshaft 42 to the valve train 63 of the cylinder head 46; and a cam chain chamber 66 through which the cam chain 65 passes, wherein, when viewed from the side facing the side wall section 67R, the coolant inlet section 85 and the coolant outlet section 86 do not coincide with the cam chain chamber 66. According to this structure, even in a configuration where the coolant inlet section 85 and the coolant outlet section 86 are located within the cylinder section 44, the cam chain chamber 66 can still be appropriately positioned.

[0264] Furthermore, the unit-type oscillating engine 13 has a thermal actuator unit 84 that switches the flow path of the cooling water. The thermal actuator unit 84 switches between the normal path N and the bypass path B. The normal path N runs from the cooling water outlet 86 through the radiator 60 and the thermal actuator unit 84 and returns to the water pump unit 81. The bypass path B runs directly from the cooling water outlet 86 through the thermal actuator unit 84 and returns to the water pump unit 81. With this structure, the thermal actuator unit 84 can easily switch between the normal path N (from the cooling water outlet 86 through the radiator 60) and the bypass path B (from the cooling water outlet 86 bypassing the radiator 60).

[0265] Furthermore, the thermal actuator unit 84 includes: an internal return water passage 84f through which cooling water for the normal path N passes; and an internal bypass water passage 84e through which cooling water for the bypass path B passes. The internal return water passage 84f and the internal bypass water passage 84e are coaxially arranged and interconnected. The thermal actuator unit 84 is fixed to the water pump unit 81. This structure simplifies the thermal actuator unit 84 and simplifies its installation.

[0266] Furthermore, the cylinder axis 44a of the cylinder section 44 extends in the longitudinal direction of the vehicle. When viewed from the side facing the side wall portion 67R of the cylinder head 46, the catalyst device 121 of the exhaust pipe 77 connected to the cylinder head 46 is positioned below the cylinder 45, and the coolant inlet portion 85 is provided on the lower surface 46a of the cylinder head 46. With this structure, the space below the longitudinally extending cylinder section 44 can be utilized efficiently, and the catalyst device 121 and the coolant inlet portion 85 can be compactly arranged.

[0267] Furthermore, the water pump unit 81 has an exhaust passage 97 extending toward the cooling water outlet 86. With this structure, gas inside the water pump unit 81 can be efficiently discharged to the cooling water outlet 86 through the exhaust passage 97.

[0268] Furthermore, a spark plug 68 is provided on the cylinder head 46, and a water pump unit 81 is provided on a side wall portion 67R of the cylinder head 46, which is located on the opposite side as the side wall portion 67L on which the spark plug 68 is provided. With this structure, the water pump unit 81 is provided on the side wall portion 67R, which is located on the opposite side of the side wall portion 67L on which the spark plug 68 is provided, thus allowing the water pump unit 81 and the spark plug 68 to be efficiently provided on the side walls 67R and 67L of the cylinder head 46.

[0269] Furthermore, the cylinder axis 44a of the cylinder section 44 extends in the longitudinal direction of the vehicle. A coolant inlet 85 is provided on the lower surface 46a of the cylinder section 44, and a coolant outlet 86 is provided on the upper surface 46b of the cylinder section 44. The coolant inlet 85, the water pump unit 81, and the coolant outlet 86 are arranged vertically. Due to this structure, the vertical arrangement of the coolant inlet 85, the water pump unit 81, and the coolant outlet 86 allows for a simpler cooling water passage configuration.

[0270] Furthermore, the water pump unit 81 has a discharge water passage 92 as a protrusion. When viewed from the side facing the side wall 67R of the cylinder head 46, the discharge water passage 92 protrudes outward from the lower surface 46a of the cylinder section 44, and a discharge outlet 93 is provided in the discharge water passage 92. According to this structure, since the discharge outlet 93 is provided in the discharge water passage 92 of the water pump unit 81, the discharge outlet 93 can be connected to the cooling water inlet 85 with a simple structure.

[0271] Furthermore, according to the first embodiment of the present invention, the automatic two-wheeled vehicle 1 includes: a water-cooled unit-type oscillating engine 13 having a cylinder section 44 having a cylinder 45 and a cylinder head 46; an exhaust pipe 77 connected to the cylinder section 44; and a catalyst device 121 disposed in the exhaust pipe 77. The cylinder axis 44a of the cylinder section 44 extends in the longitudinal direction when viewed from the side. The catalyst device 121 is disposed below the cylinder section 44. The cylinder section 44 has a cooling water inlet 85 on its lower surface, which serves as an inlet for cooling water to flow into the cylinder section 44. The cooling water inlet 85 is offset (staggered) relative to the catalyst device 121 in the longitudinal direction. According to this structure, the catalyst device 121 and the cooling water inlet 85 are staggered in the longitudinal direction on the lower side of the cylinder section 44 extending in the longitudinal direction, thus enabling efficient configuration of the catalyst device 121 and the cooling water inlet 85.

[0272] Furthermore, a cooling water inlet 85 is provided on the lower surface 46a of the cylinder head 46. This structure allows for efficient use of the space below the front-to-back extending cylinder section 44, enabling a compact arrangement of the catalyst device 121 and the cooling water inlet 85.

[0273] Furthermore, the cylinder head 46 has an exhaust pipe connection portion 46E that connects to the exhaust pipe 77, and a cooling water inlet portion 85 is adjacent to the exhaust pipe connection portion 46E. According to this structure, the exhaust pipe connection portion 46E can be efficiently cooled using cooling water.

[0274] Furthermore, the unit-type oscillating engine 13 is an upper-suspension unit-type oscillating engine 13 that is oscillating freely on the vehicle frame 12 via a linkage mechanism 48 provided above the unit-type oscillating engine 13 as a connecting part. The catalyst device 121 is configured such that its length direction faces the vehicle width direction, and when viewed from above, the catalyst device 121 coincides with the cylinder 45. According to this structure, the engine is an upper-suspension unit-type oscillating engine 13, which easily ensures space below the cylinder section 44, thus allowing the catalyst device 121 to be positioned below the cylinder section 44 with its length direction facing the vehicle width direction. In addition, since the catalyst device 121 coincides with the cylinder 45 when viewed from above, the catalyst device 121 can be efficiently positioned to avoid the coolant inlet 85 provided on the lower surface of the cylinder head 46.

[0275] Furthermore, when viewed from the side, the cooling water inlet 85 protrudes downward from the lower surface 46a, which serves as the lower wall of the cylinder section 44. With this structure, the cooling water inlet 85 can be provided without complicating the construction of the cylinder section 44 that is located inside the lower surface 46a, thus simplifying the construction of the cylinder section 44.

[0276] Furthermore, the cooling water inlet 85 has an inlet opening 85a that serves as an inlet for cooling water to flow into the cooling water inlet 85, and the inlet opening 85a opens outward in the vehicle width direction. According to this structure, cooling water can flow into the inlet opening 85a of the cooling water inlet 85 from the outside in the vehicle width direction, and space can be ensured below the cooling water inlet 85, thus facilitating the placement of the catalyst device 121.

[0277] Furthermore, the cylinder section 44 has a cooling water outlet section 86 on its upper surface 46b, which serves as an outlet for cooling water to flow out from the cylinder section 44. According to this structure, cooling water flowing in from the cooling water inlet section 85 on the lower surface 46a of the cylinder section 44 can be discharged from the cooling water outlet section 86 on the upper surface 46b of the cylinder section 44, thereby efficiently cooling the cylinder section 44.

[0278] Furthermore, a water pump unit 81 for supplying cooling water is provided on the side wall portion 67R, which is the side of the cylinder head 46, and the outlet 93 of the water pump unit 81 is directly connected to the inlet opening 85a. According to this structure, the outlet 93 of the water pump unit 81 can be connected to the cooling water inlet portion 85 with a simple construction.

[0279] Furthermore, the cylinder section 44 extends from the crankcase 43 in the longitudinal direction of the vehicle, and the connecting rod mechanism 48 is disposed above the crankcase 43. When viewed from the side, at least a portion of the catalyst device 121 is disposed below the cylinder 45 and is located in the area between imaginary lines L1 and L2. The imaginary line L1 connects the vehicle side swing shafts 48b and 48b to the front end 43d of the crankcase 43. The vehicle side swing shafts 48b and 48b connect the connecting rod mechanism 48 to the vehicle frame 12. The imaginary line L2 connects the exhaust pipe connection portion 46E of the cylinder section 44 to the vehicle side swing shafts 48b and 48b. The exhaust pipe connection portion 46E of the cylinder section 44 is connected to the end of the exhaust pipe 77. According to this structure, the catalyst device 121 can be efficiently configured in the area between the imaginary line L1 and the imaginary line L2. The imaginary line L1 connects the vehicle side swing shafts 48b and 48b to the front end 43b of the crankcase 43, and the imaginary line L2 connects the exhaust pipe connection 46E to the vehicle side swing shafts 48b and 48b.

[0280] Furthermore, according to the first embodiment of the present invention, the automatic two-wheeled vehicle 1 includes: a unit-type oscillating engine 13 having a crankcase 43 and a cylinder section 44, the cylinder section 44 extending from the crankcase 43 along the longitudinal direction of the vehicle via a cylinder axis 44a, the unit-type oscillating engine 13 being supported on a vehicle frame 12 in an oscillating manner; an exhaust pipe 77 connected to the cylinder section 44; a catalyst device 121 disposed in the exhaust pipe 77; and a radiator 60 disposed to the side of the crankcase 43, wherein, when viewed from the side, at least a portion of the catalyst device 121 is disposed in front of the crankcase 43 below the cylinder section 44, and the uppermost end 121d of the catalyst device 121 is located above the lowermost end 60a of the radiator 60.

[0281] According to this structure, at least a portion of the catalyst device 121 is positioned in front of the crankcase 43 and below the cylinder section 44, and the uppermost end 121d of the catalyst device 121 is located above the lowermost end 60a of the radiator 60, which is positioned to the side of the crankcase 43. This structure allows the radiator 60 and the catalyst device 121 to be compactly arranged vertically.

[0282] Furthermore, the radiator 60 has a lower housing 106 at its lower part, which is positioned higher at the front and lower at the rear when viewed from the side. When viewed from the side, a catalyst device 121 is disposed below the front end of the lower housing 106. According to this structure, the catalyst device 121 can be compactly disposed in the space below the lower housing 106, which is positioned higher at the front and lower at the rear when viewed from the side.

[0283] Furthermore, when viewed from the side, the lower housing 106 is positioned vertically between the catalyst unit 121 and the cylinder section 44. This configuration allows the lower housing 106 to be compactly positioned between the catalyst unit 121 and the cylinder section 44.

[0284] Furthermore, the lower housing 106 has a lower connecting pipe 111 protruding forward at its front end, and when viewed from the side, the catalyst device 121 is positioned below the lower connecting pipe 111. According to this structure, the catalyst device 121 can be compactly arranged using the space below the lower connecting pipe 111.

[0285] Furthermore, the unit-type oscillating motor 13 is supported by an oscillating shaft 48a disposed at the upper part of the unit-type oscillating motor 13, enabling it to oscillate. The radiator 60 has a radiator core 107 that is rectangular when viewed from the side. The radiator 60 is configured such that the center 107e of the radiator core 107 when viewed from the side is located behind the rotation center 42a of the crankshaft of the crankcase 43. The oscillating shaft 48a is disposed in front of the leading edge 107a of the radiator 60. According to this structure, the oscillating shaft 48a of the unit-type oscillating motor 13 is disposed in front of the leading edge 107a of the radiator 60, thus enabling the unit-type oscillating motor 13 to be compact in the vertical direction.

[0286] Furthermore, the catalyst device 121 is arranged with its length direction pointing towards the vehicle width direction, and the catalyst device 121 is offset to one side in the vehicle width direction relative to the centerline C, which is the central part of the automatic two-wheeled vehicle 1. According to this structure, it is easy to ensure space in the vehicle width direction for the catalyst device 121, thus making it easy to arrange the catalyst device 121.

[0287] Furthermore, the catalyst device 121 is positioned inside the vehicle width direction of the outer end 60b of the radiator 60. With this configuration, the catalyst device 121 can be compactly arranged, bypassing the radiator 60 in the vehicle width direction.

[0288] Furthermore, according to the first embodiment of the present invention, the automatic two-wheeled vehicle 1 includes: a unit-type swing motor 13, which is supported on the vehicle frame 12 in a swingable manner by means of a swing shaft 48a; and a radiator 60 disposed on the side of the unit-type swing motor 13, wherein the swing shaft 48a is disposed on the upper part of the unit-type swing motor 13, and when viewed from the side, the swing shaft 48a is disposed in front of the leading edge 107a of the radiator 60.

[0289] According to this structure, the swing shaft 48a is located on the upper part of the unit swing motor 13. When viewed from the side, it is positioned in front of the leading edge 107a of the radiator 60. Therefore, the unit swing motor 13 can be made compact in the vertical direction, and the swing shaft 48a can be easily accessed.

[0290] Furthermore, the radiator 60 is tilted so that its leading edge 107a is tilted backward when viewed from the side, and the swing shaft 48a is positioned rearward than the lower end 107d of the leading edge 107a when viewed from the side. With this structure, the swing shaft 48a can be compactly arranged within the space formed above the lower end 107d of the leading edge 107a of the radiator 60 due to its tilt.

[0291] Furthermore, the unit-type swing engine 13 is supported on the vehicle frame 12 in a swinging manner via a linkage mechanism 48. The linkage mechanism 48 has a swing shaft 48a, vehicle-side swing shafts 48b and 48b disposed on the vehicle frame 12, and a linkage component 48c connecting the vehicle-side swing shafts 48b and 48b with the swing shaft 48a. An upper connecting pipe 110 connected to the delivery-side hose 82 is disposed on the upper part of the radiator 60. The upper connecting pipe 110 is disposed directly above the swing shaft 48a. When viewed from the side, the delivery-side hose 82 is disposed between the swing shaft 48a and the vehicle-side swing shafts 48b and 48b.

[0292] According to this structure, the upper connecting pipe 110 and the delivery side hose 82 can be compactly configured by utilizing the space between the swing shaft 48a and the vehicle body side swing shafts 48b, 48b.

[0293] Furthermore, the upper connecting pipe 110 extends from the upper part of the radiator 60 inward and forward in the vehicle width direction, and is positioned inside the first pivot portion 130, which serves as the outer end of the linkage mechanism 48 in the vehicle width direction. With this structure, the upper connecting pipe 110 and the delivery-side hose 82 can be compactly arranged in the vehicle width direction, and the first pivot portion 130 can protect both the upper connecting pipe 110 and the delivery-side hose 82.

[0294] Furthermore, according to the first embodiment of the present invention, the automatic two-wheeled vehicle 1 includes: a unit-type oscillating engine 13 having a crankcase 43 and a cylinder section 44, the cylinder section 44 extending from the crankcase 43 along the vehicle's longitudinal direction via a cylinder axis 44a, the unit-type oscillating engine 13 being supported on a vehicle frame 12 in an oscillating manner; an exhaust pipe 77 connected to the cylinder section 44; a catalyst device 121 disposed in the exhaust pipe 77; and an exhaust gas sensor 140 disposed on the upstream side of the exhaust pipe 77. The unit-type oscillating engine 13 is supported on the vehicle frame 12 by a body-side oscillating shaft 48b disposed above the unit-type oscillating engine 13. At least a portion of the catalyst device 121 is positioned below the cylinder section 44 in a side view and is located in the area between imaginary lines L1 and L2. The imaginary line L1 connects the body-side oscillating shaft 48b to the front end 43b of the crankcase 43. The imaginary line L2 connects the exhaust pipe connection 46E of the cylinder section 44 to the body-side oscillating shaft 48b. The exhaust pipe connection 46E of the cylinder section 44 is connected to the end of the exhaust pipe 77. The exhaust pipe 77 has an upstream exhaust pipe 120 located upstream of the catalyst device 121. An upstream exhaust gas sensor 140 is disposed in the upstream exhaust pipe 120 below the cylinder section 44.

[0295] According to this structure, the catalyst device 121 can be positioned below the cylinder section 44 in the region between imaginary lines L1 and L2. Imaginary line L1 connects the vehicle-side swing shaft 48b to the front end 43b of the crankcase 43, and imaginary line L2 connects the exhaust pipe connection 46E to the vehicle-side swing shaft 48b. Furthermore, an upstream exhaust gas sensor 140 can be installed in the upstream exhaust pipe 120 below the cylinder section 44. Therefore, the catalyst device 121 and the upstream exhaust gas sensor 140 can be efficiently positioned below the cylinder section 44. Additionally, exhaust gas upstream of the catalyst device 121 can be detected.

[0296] Furthermore, the catalyst unit 121 and the upstream exhaust gas sensor 140 are positioned inside the upright portions 21, 21 of the vehicle body frame 12 when viewed from above. This structure allows the catalyst unit 121 and the upstream exhaust gas sensor 140 to be protected by the vehicle body frame 12, and also enables mass concentration in the vehicle width direction.

[0297] Furthermore, the upstream exhaust gas sensor 140 is disposed in the upstream exhaust pipe 120 at a position forward of the catalyst device 121, and is positioned from the front in the upstream exhaust pipe 120. With this configuration, the upstream exhaust gas sensor 140 is positioned from the front in the upstream exhaust pipe 120 at a position forward of the catalyst device 121, thus suppressing interference between the catalyst device 121 and the upstream exhaust gas sensor 140. Therefore, the upstream exhaust gas sensor 140 can be easily installed.

[0298] Furthermore, the upstream exhaust gas sensor 140 has a detection section 140a for detecting exhaust gas and a terminal section 140b protruding to the outside of the upstream exhaust pipe 120, and the upstream exhaust gas sensor 140 is arranged with the terminal section 140b positioned above the detection section 140a. With this structure, downward protrusion of the upstream exhaust gas sensor 140 can be suppressed, and the upstream exhaust gas sensor 140 can be compactly configured.

[0299] Furthermore, the upstream exhaust gas sensor 140 is configured along the direction of the exhaust flow. This configuration suppresses the upstream exhaust gas sensor 140 from disrupting the exhaust flow, making it easier to detect exhaust gas using the upstream exhaust gas sensor 140.

[0300] Furthermore, when viewed from the side, the upstream exhaust gas sensor 140 is covered from the outside by a side cover 34, which covers the vehicle body from the side. This configuration allows the side cover 34 to protect the upstream exhaust gas sensor 140 and improves the vehicle's appearance.

[0301] Furthermore, a fuel tank 38 is disposed in front of the upstream exhaust gas sensor 140. This configuration allows the fuel tank 38 to protect the upstream exhaust gas sensor 140.

[0302] In addition, a bottom cover 33 is provided to cover the vehicle body from below. The bottom cover 33 has a notch 33a that avoids the wiring harness 140c of the upstream exhaust gas sensor 140. According to this structure, the bottom cover 33 can protect the vehicle body, and the wiring harness 140c of the upstream exhaust gas sensor 140 can be easily arranged by avoiding the bottom cover 33 through the notch 33a.

[0303] In addition, the upstream exhaust pipe 120 has: a lower extension 125 extending downward from the exhaust pipe connection 46E; a lateral extension 126 extending outward in the vehicle width direction from the lower end of the lower extension 125; and a bend 127 that bends back in the vehicle width direction from the outer end of the lateral extension 126 and is connected to a catalyst device 121 disposed behind the lower extension 125, and an upstream exhaust gas sensor 140 is disposed in the lower extension 125.

[0304] According to this structure, since the upstream exhaust gas sensor 140 is provided in the lower extension 125, the exhaust gas near the exhaust pipe connection 46E can be detected by the upstream exhaust gas sensor 140.

[0305] Furthermore, according to the first embodiment of the present invention, the automatic two-wheeled vehicle 1 includes: a unit-type oscillating engine 13 having a crankcase 43 and a cylinder section 44, the cylinder section 44 extending from the crankcase 43 along the vehicle's longitudinal direction via a cylinder axis 44a, the unit-type oscillating engine 13 being supported on a vehicle frame 12 in an oscillating manner; a radiator 60 disposed to the side of the crankcase 43; an exhaust pipe 77 connected to the cylinder section 44; a catalyst device 121 disposed in the exhaust pipe 77; and a downstream exhaust gas sensor 141 disposed in the exhaust pipe 77, wherein, when viewed from the side, the catalyst device 121 and the downstream exhaust gas sensor 141 are separately disposed relative to the radiator 60 in the vehicle's longitudinal direction.

[0306] According to this structure, the catalyst device 121 and the downstream exhaust gas sensor 141 are positioned away from the radiator 60 in the vehicle longitudinal direction, thus enabling the catalyst device 121, the downstream exhaust gas sensor 141 and the radiator 60 to be compactly arranged in the vertical direction.

[0307] Furthermore, the unit-type oscillating engine 13 is supported on the vehicle frame 12 in an oscillating manner via a connecting rod mechanism 48, which is located above the unit-type oscillating engine 13 as a connecting part. The catalyst device 121 is positioned below the cylinder section 44 in front of the crankcase 43. With this structure, the connecting rod mechanism 48 is positioned above the unit-type oscillating engine 13, thus easily securing space below the cylinder section 44. Therefore, the catalyst device 121 can be efficiently positioned using the space below the cylinder section 44.

[0308] Furthermore, the exhaust pipe 77 has a downstream exhaust pipe 122 located downstream of the catalyst unit 121, and a downstream exhaust gas sensor 141 is disposed in the downstream exhaust pipe 122. According to this configuration, the exhaust gas passing through the catalyst unit 121 can be detected using the downstream exhaust gas sensor 141.

[0309] Furthermore, the crankcase 43 has an oil filler port 150 and a cover 151 that closes the oil filler port 150. The downstream exhaust gas sensor 141 is disposed below the cover 151 behind the radiator 60. According to this structure, the downstream exhaust gas sensor 141 can be efficiently disposed behind the radiator 60 using the space below the cover 151.

[0310] Furthermore, the axis 141d of the downstream exhaust gas sensor 141 intersects the axis 151a of the cover 151 when viewed from the side. According to this structure, the downstream exhaust gas sensor 141 is less likely to obstruct contact with the cover 151, making it easier to contact the cover 151.

[0311] Furthermore, the downstream exhaust gas sensor 141 has a detection section 141a for detecting exhaust gas and a terminal section 141b protruding outward from the downstream exhaust pipe 122. The downstream exhaust gas sensor 141 is configured such that the terminal section 141b is positioned above the detection section 141a.

[0312] According to this structure, the downward protrusion of the downstream exhaust gas sensor 141 can be suppressed, and the downstream exhaust gas sensor 141 can be compactly configured.

[0313] Furthermore, the downstream exhaust gas sensor 141 is configured along the direction of the exhaust flow. This configuration suppresses the downstream exhaust gas sensor 141 from disrupting the exhaust flow, making it easier to detect exhaust gas using the downstream exhaust gas sensor 141.

[0314] (Modified example)

[0315] Figure 19 This is a top view of the exhaust pipe 77 viewed from above in a variation of the first embodiment. Figure 20 This is a perspective view of the exhaust pipe 77 viewed from the right side in a modified example.

[0316] In the modified examples, the parts that are constructed in the same way as in the first embodiment described above are given the same reference numerals and the descriptions are omitted.

[0317] In this variation, the configuration positions of the upstream and downstream exhaust gas sensors are shown to be changed.

[0318] exist Figure 13 and Figure 16 In the diagram, the configuration positions of the upstream and downstream exhaust gas sensors in the modified example are shown using imaginary lines.

[0319] The upstream exhaust gas sensors 240, 340, and 440 described below are the same sensors as the upstream exhaust gas sensor 140, and have a detection section 140a and a terminal section 140b.

[0320] Furthermore, the downstream exhaust gas sensors 241, 341, and 441 described below are the same sensors as the downstream exhaust gas sensor 141, and have a detection section 141a and a terminal section 141b.

[0321] Reference Figure 13 , Figure 16 , Figure 19 and Figure 20Instead of the upstream exhaust gas sensor 140 in the first embodiment described above, the upstream exhaust gas sensor 240 can be disposed in the bend 127 of the upstream exhaust pipe 120. When viewed from the side, the upstream exhaust gas sensor 240 is located below the cylinder section 44.

[0322] The upstream exhaust gas sensor 240 is disposed in the upstream exhaust pipe 120 at a position forward of the catalyst device 121. The upstream exhaust gas sensor 240 is mounted on the upper surface of the outer portion 127a of the bend 127.

[0323] The upstream exhaust gas sensor 240 is configured to run along the exhaust flow of the bend 127 and is arranged with the terminal portion 140b positioned above the detection portion 140a.

[0324] The upstream exhaust gas sensor 240 is installed obliquely upward and forward from the outer surface 127a of the bend 127 and outward in the vehicle width direction.

[0325] When the exhaust gas passing through the bend 127 is referenced to an imaginary axis 12b passing through the center of the bend 127, the amount of exhaust gas passing through the outer surface of the bend 127 is greater than the amount passing through the inner surface of the bend due to centrifugal force. An upstream exhaust gas sensor 240 is provided on the outer surface of the bend 127. Therefore, the upstream exhaust gas sensor 240 can be used to efficiently detect the exhaust gas.

[0326] The bend 127 is located on the outer side of the exhaust pipe connection 46E in the vehicle width direction, making it easy to access the upstream exhaust gas sensor 240 from the outside. Therefore, the upstream exhaust gas sensor 240 has excellent maintainability.

[0327] Alternatively, the upstream exhaust gas sensor 340 can be provided in the lower extension 125 of the upstream exhaust pipe 120 instead of the upstream exhaust gas sensor 140 in the first embodiment described above.

[0328] The upstream exhaust gas sensor 340 is disposed in the upstream exhaust pipe 120, located in a position forward of the catalyst device 121. The upstream exhaust gas sensor 340 is disposed on the side of the lower extension 125 opposite to the side of the bend 127. When viewed from below, the upstream exhaust gas sensor 340 coincides with the cylinder section 44 and is located below the cylinder section 44. When viewed from above, the upstream exhaust gas sensor 340 is located between the upright sections 21, 21. The upstream exhaust gas sensor 340 is enclosed by the lower end 34a of the side cover 34. Figure 2 (Cover from the outside)

[0329] The upstream exhaust gas sensor 340 is configured to run along the exhaust flow in the lower extension 125 and is arranged with the terminal portion 140b positioned above the detection portion 140a.

[0330] The upstream exhaust gas sensor 340 is installed obliquely upwards and outwards from the side of the lower extension 125 in the vehicle width direction.

[0331] Alternatively, the upstream exhaust gas sensor 440 can be provided in the lateral extension 126 of the upstream exhaust pipe 120 instead of the upstream exhaust gas sensor 140 in the first embodiment described above.

[0332] The upstream exhaust gas sensor 440 is disposed in the upstream exhaust pipe 120, located in a position forward of the catalyst unit 121. The upstream exhaust gas sensor 440 is inserted from the front side onto the front surface of the side extension 126. When viewed from below, the upstream exhaust gas sensor 440 coincides with the cylinder section 44 and is located below the cylinder section 44. When viewed from above, the upstream exhaust gas sensor 440 is located between the upright sections 21, 21. The upstream exhaust gas sensor 440 is covered from the outside by the lower end 34a of the side cover 34.

[0333] The upstream exhaust gas sensor 440 is configured to run along the exhaust flow in the lateral extension 126 and is arranged with the terminal portion 140b positioned above the detection portion 140a.

[0334] The upstream exhaust gas sensor 440 is obliquely erected on the outside of the vehicle width direction from the front surface of the side extension 126 and upward, on the side opposite to the side of the curved portion 127.

[0335] Alternatively, the downstream exhaust gas sensor 241 can be provided in the bend 128 of the downstream exhaust pipe 122 instead of the downstream exhaust gas sensor 141 in the first embodiment described above.

[0336] The downstream exhaust gas sensor 241 is inserted from the front upper side into the upper surface of the front part of the buckling portion 128.

[0337] The downstream exhaust gas sensor 241 is configured with its terminal portion 141b positioned above the detection portion 141a.

[0338] The downstream exhaust gas sensor 241 is obliquely erected from the upper surface of the front part of the buckled portion 128. The radiator 60 is tilted so that the leading edge 107a is tilted backward when viewed from the side, and the downstream exhaust gas sensor 241 is disposed below the return hose 83.

[0339] exist Figure 16In the side view shown, the downstream exhaust gas sensor 241 and catalyst device 121 are positioned forward relative to the radiator 60. Therefore, the downstream exhaust gas sensor 241, catalyst device 121, and radiator 60 can be arranged compactly in the vertical direction.

[0340] Furthermore, the lower part of the downstream exhaust gas sensor 241 coincides with the catalyst device 121 when viewed from the side. Therefore, the downstream exhaust gas sensor 241 can be compactly arranged in the vertical direction.

[0341] When viewed from the side, the front part of the downstream exhaust pipe 122 extends forward along the lower box 106 of the radiator 60, which is inclined from front to back. The front end 122a of the downstream exhaust pipe 122 is located below the front end of the lower box 106, and the upper part of the front end 122a, including the uppermost part, is located above the lowermost end 60a of the radiator 60.

[0342] The downstream exhaust gas sensor 241 is disposed at the upper part of the front end 122a of the downstream exhaust pipe 122, and is positioned in front of the radiator 60 at a position above the lowermost end 60a of the radiator 60. Therefore, the downstream exhaust gas sensor 241 can be compactly arranged in the vertical direction.

[0343] Alternatively, the downstream exhaust gas sensor 341 can be installed in the muffler section 124 of the downstream exhaust pipe 122 instead of the downstream exhaust gas sensor 141 in the first embodiment described above.

[0344] The downstream exhaust gas sensor 341 is inserted into the upper surface of the front end of the muffler section 124 from the upper front side. The front end of the muffler section 124, on which the downstream exhaust gas sensor 341 is mounted, is formed into a cone shape whose diameter increases as it moves toward the rear.

[0345] The downstream exhaust gas sensor 341 is configured with its terminal portion 141b positioned above the detection portion 141a.

[0346] The downstream exhaust gas sensor 341 is installed obliquely upward and forward from the upper surface of the front part of the buckling portion 128 and inside the vehicle width direction.

[0347] exist Figure 16 In the side view shown, the downstream exhaust gas sensor 341 is positioned rearward relative to the radiator 60. That is, the downstream exhaust gas sensor 341 and the catalyst device 121 are positioned apart from the radiator 60 in the front-rear direction. Therefore, the downstream exhaust gas sensor 341, the catalyst device 121, and the radiator 60 can be compactly arranged in the vertical direction.

[0348] The downstream exhaust gas sensor 341 is disposed below the cover 151. The axis 141d of the detection part 141a of the downstream exhaust gas sensor 341 intersects the axis 151a of the cover 151.

[0349] Alternatively, the downstream exhaust gas sensor 441 can be provided in the bend 128 of the downstream exhaust pipe 122 instead of the downstream exhaust gas sensor 141 in the first embodiment described above.

[0350] The downstream exhaust gas sensor 441 is inserted from the upper side of the outer side in the vehicle width direction into the upper surface of the rear part of the buckling portion 128.

[0351] The downstream exhaust gas sensor 441 is configured with its terminal portion 141b positioned above the detection portion 141a.

[0352] The downstream exhaust gas sensor 441 is installed obliquely upward from the upper surface of the rear part of the buckled portion 128 in the vehicle width direction.

[0353] (Second Implementation)

[0354] Below, refer to Figure 21 and Figure 22 The second embodiment of the present invention will now be described. In this second embodiment, parts that are identical in structure to those in the first embodiment are given the same reference numerals and their descriptions are omitted.

[0355] The difference between this second embodiment and the first embodiment described above lies in the structure of the exhaust pipe 277 and the linkage mechanism 248.

[0356] Figure 21 This is a right-side view of the periphery of the radiator 60 and the linkage mechanism 248 in the second embodiment. Figure 22 This is a view of the unit-type oscillating engine 213 and its peripheral portion from below in the second embodiment.

[0357] like Figure 21 and Figure 22 As shown, in the second embodiment, the unit-type swing engine 213 is supported on the vehicle frame 12 in a swinging manner by means of a linkage mechanism 248 provided at the lower part of the crankcase 43.

[0358] The linkage mechanism 248 includes: a body-side connecting portion 248a mounted on the body frame 12; an engine-side connecting portion 248b extending forward from the front of the lower part of the crankcase 43; and a pivot 248c connecting the body-side connecting portion 248a and the engine-side connecting portion 248b. The single-unit oscillating engine 213 oscillates around the pivot 248c extending in the vehicle width direction. The engine-side connecting portion 248b is located in the crankcase 43 at a position lower than the cylinder axis 44a of the cylinder section 44.

[0359] The exhaust pipe 277 includes: a first exhaust pipe 220 connected to the exhaust pipe connection portion 46E of the cylinder head 46; a catalyst device 221 connected to the downstream end of the first exhaust pipe 220; and a second exhaust pipe 222 connected to the downstream end of the catalyst device 221.

[0360] The catalyst device 221 is located between the first exhaust pipe 220 and the second exhaust pipe 222 in the direction of exhaust flow, and is positioned in the middle of the exhaust pipe 277.

[0361] The first exhaust pipe 220 extends outward in the vehicle width direction from the exhaust pipe connector 46E, passing below the cylinder section 44. The downstream end of the first exhaust pipe 220 bends backward below the right-side upright section 21.

[0362] Catalyst unit 221 is a cylindrical component containing a catalyst carrier. Catalyst unit 221 extends rearward from the downstream end of the first exhaust pipe 220. Catalyst unit 221 is arranged with its length direction facing forward and backward, and when viewed from the side, catalyst unit 221 is configured with the front higher than the rear.

[0363] The catalyst device 221 is located below the right-side upright portion 21, on the outer side of the cylinder portion 44 in the vehicle width direction. The catalyst device 221 has... Figure 22 When viewed from below, the overlapping part 221a is the part that overlaps with the front of the radiator 60 from below.

[0364] When viewed from the side, the catalyst device 221 is positioned in front of the front end 43b of the crankcase 43, below the cylinder section 44. When viewed from the side, the rear of the catalyst device 221 is positioned below the lower connecting pipe 111, which is the lower part of the front end of the radiator 60.

[0365] The uppermost end 221d of the catalyst device 221 is located above the lowermost end 60a of the radiator 60.

[0366] In this way, by setting the catalyst device 221 to coincide with the lower part of the radiator 60 in the vertical direction, the catalyst device 221 and the radiator 60 can be compactly arranged in the vertical direction.

[0367] The second exhaust pipe 222 extends rearward from the downstream end of the catalyst unit 221. The second exhaust pipe 222 has a muffler section 224 at its rear end.

[0368] Furthermore, the first and second embodiments described above are used to illustrate one way of applying the present invention, and the present invention is not limited to the first and second embodiments described above.

[0369] In the above embodiments, the cooling water inlet 85 and cooling water outlet 86 are described as being located on the cylinder head 46; however, the present invention is not limited thereto. For example, the cooling water inlet may be located on the lower surface of the cylinder 45, and the cooling water outlet may be located on the upper surface of the cylinder 45.

[0370] In the above embodiments, an automatic two-wheeled vehicle 1 was described as an example of a saddle-riding vehicle. However, the present invention is not limited thereto. The present invention can also be applied to saddle-riding vehicles such as three-wheeled saddle-riding vehicles with two front wheels or two rear wheels, and saddle-riding vehicles with four or more wheels.

Claims

1. A saddle-type vehicle comprising: a unit-type oscillating engine (13) supported on a body frame (12) in an oscillating manner by means of an oscillating shaft (48a); and a radiator (60) disposed to the side of the unit-type oscillating engine (13); the oscillating shaft (48a) being disposed on the upper part of the unit-type oscillating engine (13), characterized in that, The unit-type oscillating engine (13) is supported by a oscillating shaft (48b) on the side of the vehicle body frame (12) and a oscillating shaft (48a) on the oscillating shaft connection (43d) at the top of the unit-type oscillating engine (13) to enable it to oscillate. The radiator (60) has a radiator core (107) that is rectangular when viewed from the side. When viewed from the side, the swing shaft (48a) is positioned below the upper end (107c) of the leading edge (107a) of the radiator core (107) and above the lower end (107d) of the leading edge (107a). The radiator (60) is tilted so that the leading edge (107a) is tilted backward when viewed from the side.

2. The saddle-type vehicle according to claim 1, characterized in that, When viewed from the side, the swing shaft (48a) is positioned behind the lower end (107d) of the leading edge (107a).

3. The saddle-type vehicle according to claim 1 or 2, characterized in that, The radiator (60) is configured such that the center (107e) of the radiator core (107) when viewed from the side is located behind the rotation center (42a) of the crankshaft (42) of the unitary oscillating engine (13).

4. The saddle-type vehicle according to claim 1 or 2, characterized in that, The unit-type swing engine (13) is supported on the vehicle frame (12) in a swingable manner via a linkage mechanism (48), the linkage mechanism (48) having: the swing shaft (48a); and a linkage member (48c) that connects the vehicle-side swing shaft (48b) to the swing shaft (48a). An upper connecting pipe (110) connected to the radiator hose (82) is provided on the upper part of the radiator (60). The radiator hose (82) is positioned between the swing shaft (48a) and the vehicle body side swing shaft (48b) when viewed from the side.

5. The saddle-type vehicle according to claim 4, characterized in that, The upper connecting pipe (110) extends from the upper part of the radiator (60) inward and forward in the vehicle width direction.

6. The saddle-type vehicle according to claim 1 or 2, characterized in that, The unit-type oscillating engine (13) includes: a water pump unit (81) disposed on one side of the cylinder section (44) of the unit-type oscillating engine (13) in the vehicle width direction; and a thermal actuator unit (84) disposed behind the water pump unit (81). The radiator (60) is positioned behind the water pump unit (81) and on the outside of the unit-type oscillating engine (13).

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