Saddle-type vehicle

Abstract

To provide a catalyst device within a front part of an exhaust pipe in a saddle riding type vehicle having a structure in which the exhaust pipe passes through the side of an engine.SOLUTION: In a saddle-riding type vehicle 1, an exhaust port of an engine 31 is open to the front while inclining to the left side. An exhaust pipe 60 includes: a first portion 61 extending downward from the exhaust port of the engine 31 through a region located in front of the engine 31 and on a left side of a down frame 5; a second portion 62 extending upward through a region located in front of the engine 31 and on a right side of the down frame 5 after extending from a downstream side end portion of the first portion 61 to the right side of the down frame 5 through a region in front of and below the down frame 5; a third portion 63 extending rearward from a downstream side end portion of the second portion 62 through an area located at a right side of the engine 31; and a fourth portion 64 extending from a downstream side end portion of the third portion 63 to a muffler. A first catalyst device 71 is disposed within a portion, located in front of the engine 31 and on the right side of the down frame 5, of the second portion 62 of the exhaust pipe 60.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a straddle-type vehicle equipped with an internal combustion engine as an engine. [Background technology]

[0002] Generally, there are two types of saddle-type vehicles: those designed for on-road riding, i.e., on paved and level roads, and those designed for both on-road riding and off-road riding, i.e., on unpaved or rough roads. Saddle-type vehicles designed for on-road riding include naked bikes, super sports bikes, cruisers, etc. Saddle-type vehicles designed for both on-road and off-road riding include dual-purpose bikes, adventure bikes, on-off models, scramblers, etc. There are also saddle-type vehicles designed for off-road competitions such as motocross, trials, and enduro.

[0003] Hereinafter, a saddle-type vehicle designed for on-road riding will be referred to as an "on-road vehicle." Also, a saddle-type vehicle designed for both on-road and off-road riding, and a saddle-type vehicle designed for off-road competitions will be referred to as an "off-road vehicle."

[0004] Compared to on-road vehicles, off-road vehicles have a higher ground clearance and a longer suspension stroke. Furthermore, many off-road vehicles have exhaust pipes and mufflers located high above the ground.

[0005] Here, we will compare the exhaust pipe arrangements of on-road and off-road vehicles in detail. An exhaust pipe for an on-road vehicle typically extends from an exhaust port opening at the front of the engine's cylinder head, downward in front of the engine's cylinder head, cylinder, and crankcase, then curves rearward, and then extends approximately horizontally rearward below the crankcase (between the bottom of the crankcase and the ground), at least to a position beyond the crankcase. In contrast, an exhaust pipe for an off-road vehicle (especially a saddle-type vehicle for off-road racing) extends from an exhaust port opening at the front of the cylinder head, initially downward in front of the cylinder head, then immediately curves sideways, then curves rearward, and then extends approximately horizontally rearward along the cylinder head or the side of the cylinder, at least to a position beyond the cylinder or the cylinder head. A notable difference in the location of exhaust pipes between on-road and off-road vehicles is that the exhaust pipe of an on-road vehicle passes below the crankcase, while the exhaust pipe of an off-road vehicle passes along the side of the cylinder head or cylinder. When traveling off-road, stones and other debris from the ground are frequently kicked up by the wheels and thrown into the air. By locating the exhaust pipe at a high position away from the ground, it is possible to prevent such stones from hitting the exhaust pipe, thereby protecting the exhaust pipe. From this perspective, in many off-road vehicles, the exhaust pipe is routed so that it passes along the side of the cylinder head or cylinder, rather than passing below the crankcase.

[0006] On the other hand, in order to protect the global environment, there is a demand to reduce emissions of air pollutants such as nitrogen oxides from engines. In response to this demand, straddle-type vehicles are equipped with catalytic converters in which a catalyst is supported on a monolithic carrier having, for example, a honeycomb structure, in order to reduce the amount of air pollutants in the exhaust gas.

[0007] In many conventional saddle-ride type vehicles, the catalytic converter is installed inside the muffler or inside the rear (downstream) part of the exhaust pipe near the muffler. However, recently, an increasing number of saddle-ride type vehicles have installed the catalytic converter inside the front (upstream) part of the exhaust pipe.

[0008] The catalyst in a catalytic converter increases in temperature and becomes activated as exhaust gas from the engine flows through the catalytic converter. When the catalytic converter is installed far from the engine's exhaust port, such as inside a muffler, the temperature of the exhaust gas drops as it passes through the exhaust pipe and reaches the catalytic converter. As a result, low-temperature exhaust gas flows through the catalytic converter. This slows the temperature rise of the catalyst, which increases the time it takes for the catalyst to activate after the engine starts. As a result, the catalyst may not be able to sufficiently reduce air pollutants during engine startup. In contrast, when the catalytic converter is installed inside the front portion of the exhaust pipe, the distance between the catalytic converter and the engine's exhaust port is reduced. Therefore, high-temperature exhaust gas flows through the catalytic converter immediately after it is discharged from the exhaust port, allowing the catalyst's temperature to rise quickly and the catalyst to be activated quickly during engine startup. As a result, the catalyst can sufficiently reduce air pollutants even during engine startup. Recently, in response to the growing demand for global environmental conservation, straddle-type vehicles equipped with a catalytic converter mounted inside the front portion of the exhaust pipe are becoming increasingly popular in order to improve the catalytic converter's ability to purify exhaust gases when the engine is started.

[0009] Japanese Patent Application Laid-Open Publication No. 2008-64068 (Patent Document 1) describes a straddle-type vehicle that is an off-road vehicle. In this straddle-type vehicle, the exhaust pipe extends forward from the engine's exhaust port, then bends rearward, and then passes to the right of the engine, above the engine's crankcase, and extends rearward again. The straddle-type vehicle also has a main catalyst and a pre-catalyst, the main catalyst being located inside a silencer, and the pre-catalyst being located inside the exhaust pipe just after it passes above the crankcase. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-64068 Summary of the Invention [Problem to be solved by the invention]

[0011] In a saddle-type vehicle such as the off-road vehicle described above, in which the exhaust pipe does not pass below the engine but passes along the side of the engine, such as alongside the engine cylinder or cylinder head, it is not easy to properly install a catalytic converter inside the front portion of the exhaust pipe, as will be described below.

[0012] In a saddle-type vehicle in which the exhaust pipe passes along the side of the engine, the front of the exhaust pipe refers to the part of the exhaust pipe between the engine's exhaust port and the part of the exhaust pipe that passes along the side of the engine.

[0013] First, when a catalytic converter is provided inside the exhaust pipe between the engine exhaust port and the side of the engine, the following problems arise.

[0014] In saddle-type vehicles, such as the off-road vehicle described above, where the exhaust pipe runs along the side of the engine rather than underneath it, the exhaust pipe extends downward from the exhaust port opening at the front of the cylinder head, then immediately curves to the side, then curves rearward, and reaches the side of the engine. Therefore, the length of the exhaust pipe between the engine's exhaust port and the side of the engine is short. This makes it difficult to install a catalytic converter inside that section.

[0015] Next, when a catalytic converter is provided inside the portion of the exhaust pipe that passes beside the engine, the following problem arises.

[0016] In a saddle-ride type vehicle having an exhaust pipe that passes alongside the engine, the exhaust pipe passes alongside the engine and then passes on the inside side of the legs of a driver seated in the seat, in a position very close to those legs. For example, if the exhaust pipe passes to the right of the engine, the exhaust pipe passes to the right of the engine and then passes to the left of the knee or calf of the right leg of the driver seated in the seat, in a position very close to those knees or calves. Saddle-ride type vehicles having an exhaust pipe that passes alongside the engine are usually provided with a heat shield to protect the driver's legs from heat from the exhaust pipe. The heat shield is provided in the area between the part of the exhaust pipe that passes alongside the engine and the part immediately thereafter and the driver's legs, so as to block the gap between the exhaust pipe and the driver's legs.

[0017] If the diameter of the catalytic converter is larger than the normal diameter of the exhaust pipe, the diameter of the portion of the exhaust pipe where the catalytic converter is installed will be larger than the normal diameter of the exhaust pipe (the diameter of the portion of the exhaust pipe where the catalytic converter is not installed). Therefore, if such a catalytic converter is installed inside the portion of the exhaust pipe that passes beside the engine, the portion of the exhaust pipe that passes on the inside of the driver's legs may become larger in diameter. In this case, the portion of the saddle-type vehicle between the right and left legs of the driver seated in the seat will become wider, forcing the driver to ride the saddle-type vehicle with their legs spread apart, which will worsen the driver's driving posture. This worsening driving posture will result in a decrease in the maneuverability of the saddle-type vehicle.

[0018] Furthermore, when a catalytic converter with a diameter smaller than the normal diameter of the exhaust pipe is installed inside the exhaust pipe, the diameter of the portion of the exhaust pipe where the catalytic converter is installed may not be larger than the normal diameter of the exhaust pipe. However, installing a catalytic converter inside the exhaust pipe tends to cause the portion of the exhaust pipe where the catalytic converter is installed to be hotter than the portion without the catalytic converter. Therefore, even when a catalytic converter with a diameter smaller than the normal diameter of the exhaust pipe is installed inside the portion of the exhaust pipe that passes beside the engine, it is necessary to increase the distance between the exhaust pipe and the shielding plate to protect the driver's legs from the heat from the exhaust pipe. As a result, the driver's driving posture may be adversely affected, similar to when a catalytic converter with a diameter larger than the normal diameter of the exhaust pipe is installed inside the portion of the exhaust pipe that passes beside the engine. Furthermore, a catalytic converter with a diameter smaller than the normal diameter of the exhaust pipe has a lower exhaust gas purification capacity than a catalytic converter with a diameter larger than the normal diameter of the exhaust pipe, and therefore may not be able to sufficiently purify the exhaust gas.

[0019] Furthermore, in a straddle-type vehicle described in Japanese Patent Laid-Open Publication No. 2008-64068 (Patent Document 1), the exhaust pipe passes beside the engine cylinder or cylinder head, then passes closer to the center of the saddle-type vehicle in the left-right direction than the engine cylinder or cylinder head and extends rearward. A catalytic converter having a diameter larger than the normal diameter of an exhaust pipe is provided inside the exhaust pipe, passing closer to the center of the saddle-type vehicle in the left-right direction than the engine cylinder or cylinder head (see Figure 3 of the publication). With this configuration, by providing a catalytic converter inside the exhaust pipe, it is possible to prevent the portion of the exhaust pipe between the driver's right and left legs in the seat of the saddle-type vehicle from becoming wider to some extent, even if the diameter of the exhaust pipe is increased in the portion that passes on the inside sides of the driver's legs. However, in this configuration, in order to pass the exhaust pipe, which has a larger diameter due to the installation of the catalytic device, through the center of the saddle-ride type vehicle in the left-right direction, it is necessary to expand the space surrounded by the main frame, rear cushion, engine cylinder, etc., which could result in the saddle-ride type vehicle becoming larger.

[0020] The present invention has been made in consideration of the problems such as those described above, and an object of the present invention is to make it possible to appropriately install a catalytic converter inside the front part of the exhaust pipe in a saddle-type vehicle having a structure in which the exhaust pipe passes beside the engine rather than below the engine. [Means for solving the problem]

[0021] In order to solve the above problems, the present invention provides a straddle-type vehicle including: a head pipe; a main frame extending rearward from the head pipe; a down frame extending downward from the head pipe; an engine having a crankcase, a cylinder provided above the crankcase, and a cylinder head provided above the cylinder, and disposed below the main frame and behind the down frame; a silencer disposed behind the engine and for reducing exhaust noise of exhaust gas discharged from an exhaust port provided in the cylinder head; an exhaust pipe connecting the exhaust port and the silencer and sending the exhaust gas discharged from the exhaust port to the silencer; and a catalytic converter disposed midway through the exhaust pipe and for purifying the exhaust gas flowing inside the exhaust pipe, wherein the exhaust port is provided to reduce noise generated by the cylinder. the exhaust pipe has a first portion extending downward from the exhaust port through a region in front of the engine and on one side of the down frame in the left-right direction, a second portion extending from a downstream end of the first portion through a front or lower-front region of the down frame to the other side of the down frame in the left-right direction, and then extending upward through a region in front of the engine and on the other side of the down frame in the left-right direction, a third portion extending rearward from the downstream end of the second portion through a region on the other side of the engine in the left-right direction, and a fourth portion extending from the downstream end of the third portion to reach the muffler, and the catalytic device is disposed inside a portion of the second portion of the exhaust pipe that is located in front of the engine and on the other side of the down frame in the left-right direction. and is disposed at a portion higher than the lower end of the down frame and lower than the exhaust port. It is characterized by the fact that [Effects of the Invention]

[0022] According to the present invention, in a straddle-type vehicle having an exhaust pipe that passes beside the engine rather than below it, a catalytic converter can be appropriately provided inside the front portion of the exhaust pipe. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an external view showing the entire saddle-ride type vehicle according to an embodiment of the present invention as viewed from the right side; [Figure 2] 1 is an external view showing a portion of a saddle-ride type vehicle according to an embodiment of the present invention in which an engine is provided, as viewed from the right side. [Figure 3] 1 is an external view showing a portion of a saddle-ride type vehicle according to an embodiment of the present invention in which an engine is provided, as viewed from the front. [Figure 4] 1 is an external view showing a portion of a saddle-ride type vehicle according to an embodiment of the present invention in which an engine is provided, as viewed from the left side. [Figure 5] 1 is an external view showing a portion of a saddle-ride type vehicle according to an embodiment of the present invention in which an engine is provided, as viewed from above; [Figure 6] 1 is an external view showing a portion of a straddle-type vehicle according to an embodiment of the present invention in which an engine is provided, as viewed from below. [Figure 7] 1 is an external view showing an engine of a saddle-ride type vehicle according to an embodiment of the present invention as viewed from the front. [Figure 8] 1 is an explanatory view showing an exhaust pipe, a first catalytic converter housing, a muffler, etc. of a saddle-ride type vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] A saddle-ride type vehicle according to an embodiment of the present invention includes a head pipe, a main frame extending rearward from the head pipe, a down frame extending downward from the head pipe, and an engine disposed below the main frame and rearward of the down frame. The engine has a crankcase, cylinders disposed above the crankcase, and a cylinder head disposed above the cylinders. The saddle-ride type vehicle according to an embodiment of the present invention also includes a silencer that reduces exhaust noise from exhaust gases emitted from an exhaust port of the engine, an exhaust pipe that sends the exhaust gases emitted from the exhaust port to the silencer, and a catalytic converter that purifies the exhaust gases flowing through the exhaust pipe.

[0025] In a saddle-ride type vehicle according to an embodiment of the present invention, an engine exhaust port is disposed in front of the cylinder head and opens forward while tilting to one side in the left-right direction. The silencer is disposed behind the engine. An exhaust pipe connects the engine exhaust port to the silencer. The exhaust pipe has a first section extending downward from the engine exhaust port through a region in front of the engine and on one side of the down frame in the left-right direction; a second section extending from a downstream end of the first section through a region in front of or below-front of the down frame to the other side of the down frame in the left-right direction and then extending upward through a region in front of the engine and on the other side of the down frame in the left-right direction; a third section extending rearward from the downstream end of the second section through a region on the other side of the engine in the left-right direction; and a fourth section extending from the downstream end of the third section to the silencer. The catalytic converter is disposed midway through the exhaust pipe. Specifically, the catalytic converter is disposed within a portion of the second section of the exhaust pipe that is located in front of the engine and on the other side of the down frame in the left-right direction.

[0026] According to the straddle-type vehicle of the embodiment of the present invention, the catalytic device can be appropriately provided inside the front portion (upstream side) of the exhaust pipe.

[0027] That is, as described above, in conventional saddle-ride vehicles in which the exhaust pipe passes along the side of the engine, the length of the exhaust pipe from the engine exhaust port to the side of the engine is short, making it difficult to install a catalytic converter in this section. However, the exhaust pipe of the saddle-ride vehicle of this embodiment has a first section that extends downward from the engine exhaust port to a region forward of the engine and on one lateral side of the down frame, and a second section that extends from the downstream end of the first section through a region forward or below-forward of the down frame to the other lateral side of the down frame, and then extends upward through a region forward of the engine and on the other lateral side of the down frame. This configuration ensures a sufficient length of the exhaust pipe for installing a catalytic converter in the section of the exhaust pipe located in front of the engine and on the other lateral side of the down frame, making it easy to install a catalytic converter in that section. In particular, a large catalytic converter with a diameter larger than the normal diameter of the exhaust pipe and high exhaust gas purification capacity can be easily installed in the section of the exhaust pipe located in front of the engine and on the other lateral side of the down frame.

[0028] As described above, in a conventional saddle-ride vehicle having an exhaust pipe that passes beside the engine, if a catalytic converter with a diameter larger than the normal diameter of the exhaust pipe is provided inside the portion of the exhaust pipe that passes beside the engine, the portion between the right and left legs of the driver seated on the seat of the saddle-ride vehicle becomes wider, which can lead to poor driving posture. Furthermore, even if a catalytic converter with a diameter smaller than the normal diameter of the exhaust pipe is provided inside the portion of the exhaust pipe that passes beside the engine, it is necessary to increase the distance between the exhaust pipe and the shielding plate to protect the driver's legs from heat from the exhaust pipe, which can lead to poor driving posture. However, in the saddle-ride vehicle of this embodiment, the catalytic converter is provided inside the second portion of the exhaust pipe that is located in front of the engine and on the other lateral side of the down frame, so this problem does not arise. In other words, the saddle-ride vehicle of this embodiment can prevent the driver's driving posture from being poorly adjusted due to the catalytic converter being provided inside the front portion of the exhaust pipe.

[0029] Furthermore, as mentioned above, in the saddle-riding vehicle described in JP 2008-64068 A (Patent Document 1), by providing a catalytic device with a diameter larger than the normal diameter of the exhaust pipe inside a portion of the exhaust pipe that passes closer to the center of the saddle-riding vehicle in the left-right direction than the engine cylinder or cylinder head and extends rearward, it becomes necessary to expand the space surrounded by the main frame, rear cushion, engine cylinder, etc., which could result in a problem that the saddle-riding vehicle may become larger. However, because the catalytic device of the saddle-riding vehicle of this embodiment is located inside a portion of the second portion of the exhaust pipe that is located forward of the engine and on the other left-right side of the down frame, this problem does not arise.

[0030] In addition, in the saddle-ride type vehicle of this embodiment, the engine exhaust port is located in front of the cylinder head and opens forward while tilting to one side in the left-right direction. This allows the exhaust pipe to be easily connected to the exhaust port without providing a portion at the upstream end (first portion) of the exhaust pipe that is locally bent with a large curvature. Furthermore, the exhaust pipe can be extended from the exhaust port to a position in front of or below the down frame in front of the down frame in the upstream end (first portion) without providing a portion that is bent in a complex manner, such as an S-shape or crank shape. [Example]

[0031] An embodiment of a saddle-type vehicle of the present invention will be described with reference to the drawings. In the following embodiments, when describing the directions of front (Fd), rear (Bd), up (Ud), down (Dd), left (Ld), and right (Rd), they are based on the arrows drawn at the bottom right of each drawing.

[0032] (saddle-type vehicle) FIG. 1 shows an entire saddle-riding vehicle 1 according to an embodiment of the present invention, as viewed from the right. In FIG. 1, only the outlines of the seat and cowl are shown by two-dot chain lines, and some components provided on the saddle-riding vehicle 1, such as the fuel tank, brake calipers, rear cushion, and drive chain, are not shown. FIGS. 2 to 6 show the portion of the saddle-riding vehicle 1 where the engine 31 is provided. In detail, FIG. 2 shows the portion as viewed from the right, FIG. 3 shows the portion as viewed from the front, FIG. 4 shows the portion as viewed from the left, FIG. 5 shows the portion as viewed from above, and FIG. 6 shows the portion as viewed from below. In FIGS. 2 to 6, the steering shaft, front fork 15, handlebars 18, swing arm 19, and the like have been removed. In addition, in FIGS. 5 and 6, radiators 42 and 43 have been removed.

[0033] 1, saddle-riding vehicle 1 is an off-road vehicle, specifically a saddle-riding vehicle for off-road racing. Saddle-riding vehicle 1 includes a body frame 2 that forms the skeleton of the vehicle. Body frame 2 includes a head pipe 3, a pair of main frames 4, a down frame 5, a pair of under frames 6, and a pair of seat rails 7.

[0034] As shown in FIGS. 2 and 3, the head pipe 3 is disposed at the center in the left-right direction of the upper front part of the saddle riding type vehicle 1.

[0035] Of the pair of main frames 4, one main frame 4 extends over the right portion of the saddle-riding vehicle 1 from the upper front portion of the saddle-riding vehicle 1 to the lower midsection of the saddle-riding vehicle 1 in the longitudinal direction. Specifically, as shown in FIG. 5, the front portion 4A of the one main frame 4 extends rearward and to the right from the head pipe 3, then curves gently, and then extends rearward. As shown in FIG. 2, the front portion 4A of the one main frame 4 extends rearward and tilts downward from the upper right portion of the saddle-riding vehicle 1. As shown in FIG. 2, the rear portion 4B of the one main frame 4 extends downward and tilts slightly rearward from the right portion of the midsection of the saddle-riding vehicle 1 in the longitudinal direction. The other main frame 4 extends over the left portion of the saddle-riding vehicle 1 from the upper front portion of the saddle-riding vehicle 1 to the lower midsection of the saddle-riding vehicle 1 in the longitudinal direction. The shape and arrangement of the other main frame 4 are bilaterally symmetrical to the shape and arrangement of the one main frame 4, as shown in FIGS. 4 and 5. The front end of each main frame 4 is connected to a head pipe 3 .

[0036] 2 and 3, the down frame 5 extends downward while tilting slightly rearward from the upper front portion of the saddle riding type vehicle 1 to the lower front portion of the saddle riding type vehicle 1 in the left-right center of the saddle riding type vehicle 1. The upper end portion of the down frame 5 is connected to the head pipe 3. The lower end of the down frame 5 is positioned higher than the lower end of the rear portion 4B of the main frame 4.

[0037] Of the pair of underframes 6, one underframe 6 extends over the right portion of the saddle-riding vehicle 1 from the lower front portion of the saddle-riding vehicle 1 to the lower portion of the longitudinal middle portion of the saddle-riding vehicle 1. Specifically, as shown in FIGS. 3 and 6 , one underframe 6 extends from the lower end of the down frame 5 toward the lower right and rearward, then curves gently, and then, as shown in FIG. 2 , extends approximately horizontally rearward from the lower right portion of the saddle-riding vehicle 1. The other underframe 6 extends over the left portion of the saddle-riding vehicle 1 from the lower front portion of the saddle-riding vehicle 1 to the lower portion of the longitudinal middle portion of the saddle-riding vehicle 1. As shown in FIGS. 3 , 4 , and 6 , the shape and arrangement of the other underframe 6 are bilaterally symmetrical to the shape and arrangement of the first underframe 6. The front ends of each underframe 6 are connected to the lower ends of the down frame 5. The rear ends of each underframe 6 are connected to a bridge frame 8 that is installed between the lower ends of the rear portions 4B of the pair of main frames 4, as shown in FIG. 6 .

[0038] 1, 2 and 4, the pair of seat rails 7 extend on the left and right sides of the saddle riding type vehicle 1 from an upper part of the middle part in the fore-and-aft direction of the saddle riding type vehicle 1 to an upper part of the rear end of the saddle riding type vehicle 1. In addition, a reinforcing frame 9 that reinforces the front part of the body frame 2 is provided between the down frame 5 and the main frame 4 (see FIGS. 2 and 4), and a reinforcing frame 10 (see FIG. 1) that reinforces the rear part of the body frame 2 is provided between the lower part of the rear part 4B of the main frame 4 and the seat rails 7.

[0039] As shown in Fig. 1, a steering shaft is rotatably provided within the head pipe 3, and a front fork 15 is attached to the steering shaft via a bracket. A front wheel 16 is rotatably attached to the lower end of the front fork 15. A front fender 17 is provided above the front wheel 16. A handlebar 18 is provided above the head pipe 3, and the handlebar 18 is attached to the steering shaft via a bracket. A swing arm 19 is swingably attached to the lower portion of the rear section 4B of the pair of main frames 4, and a rear wheel 20 is rotatably attached to the rear end of the swing arm 19.

[0040] The saddle-riding type vehicle 1 also includes an engine 31, which is a power source for traveling. An internal combustion engine is used as the engine 31. In this embodiment, the engine 31 is a four-stroke, water-cooled, single-cylinder gasoline engine. The engine 31 is disposed approximately in the center of the saddle-riding type vehicle in the longitudinal direction and the lateral direction. The engine 31 is disposed so as to be surrounded by a pair of main frames 4, a down frame 5, and a pair of under frames 6. Specifically, the engine 31 is disposed below the front portions 4A of the pair of main frames 4, in front of the rear portions 4B of the pair of main frames 4, behind the down frame 5, and above the pair of under frames 6. The engine 31 is also supported by these frames via engine mounts.

[0041] As shown in FIG. 4, the engine 31 has a crankcase 32, a cylinder 33, a cylinder head 34, and a cylinder head cover 35. The crankcase 32 is located at the bottom of the engine 31, and a crankshaft is provided inside the crankcase 32. The engine 31 is a so-called power unit integrated with a transmission, and the transmission is provided at the rear of the crankcase 32. The cylinder 33 is located above the crankcase 32, and a piston is provided inside the cylinder 33. The cylinder head 34 is located above the cylinder 33. An intake port (not shown) is formed at the rear of the cylinder head 34, which sends an air-fuel mixture into the cylinder 33. An exhaust port 36 is formed at the front of the cylinder head 34, which discharges combustion gas (exhaust gas) out of the cylinder 33 (see FIG. 7). An intake valve, an exhaust valve, a camshaft, etc. are provided inside the cylinder head 34, and a spark plug (not shown) etc. are also attached to the cylinder head 34. A cylinder head cover 35 covers the upper part of the cylinder head 34 .

[0042] FIG. 7 shows the engine 31 as viewed from the front. As shown in FIG. 7, the exhaust port 36 of the engine 31 is located on the front surface of the cylinder head 34, at a position slightly to the left of the center in the left-right direction. In a front view of the saddle-riding type vehicle 1, only a portion of the right end of the exhaust port 36 overlaps with the down frame 5. The exhaust port 36 opens forward on the front surface of the cylinder head 34 while tilting to the left (to one side in the left-right direction). That is, the opening direction of the exhaust port 36 is toward the left front. The dash-dotted line L in FIG. 5 is a straight line that passes through the center in the left-right direction of the saddle-riding type vehicle 1 and extends in the front-rear direction. The dash-dotted line M in FIG. 5 is a straight line that passes through the center of the exhaust port 36 and extends in the opening direction of the exhaust port 36. The angle α formed by the dash-dotted line L and the dash-dotted line M indicates the tilt angle of the exhaust port 36 to the left. In this embodiment, the exhaust port 36 is tilted leftward by approximately 36 degrees, as shown in FIG. 5. The leftward tilt angle of the exhaust port 36 is not limited to 36 degrees, but is preferably equal to or greater than approximately 20 degrees and equal to or less than approximately 70 degrees. The minimum tilt angle of the exhaust port 36 that allows the upstream end of the exhaust pipe 60 to be easily connected to the exhaust port 36 from the left side of the down frame 5 is approximately 20 degrees, and the maximum angle that allows the first portion 61 of the exhaust pipe 60 to be easily routed so that it does not protrude to the left from the leftmost portion of the engine 31 (the left surface of the magneto cover 39) is approximately 70 degrees.

[0043] 2, a water pump 37 is provided on the outer surface of the front right portion of the crankcase 32 to circulate coolant, mainly for cooling the engine 31. A clutch is provided in the rear right portion of the crankcase 32, and a clutch cover 38 that covers the clutch is provided on the outer surface of the rear right portion of the crankcase 32. As shown in FIG. 4, a power generator that generates electricity using the rotation of the crankshaft is provided in the front left portion of the crankcase 32, and a magneto cover 39 that covers the power generator is provided on the outer surface of the front left portion of the crankcase 32.

[0044] In addition, in the saddle-type vehicle 1, an air cleaner 40 is provided above and behind the engine 31, as shown in Fig. 1, and an intake pipe 41 is provided between the air cleaner 40 and the intake port of the engine 31, as shown in Fig. 4. Although not shown in detail, a throttle device, a fuel injector, etc. are provided around the intake port of the engine 31.

[0045] Furthermore, in the saddle-ride type vehicle 1, two radiators 42, 43 are provided in front of the cylinder head 34 of the engine 31 as heat exchangers that use running wind to cool the cooling water that mainly cools the engine 31. As shown in Fig. 3, one radiator 42 is disposed on the right side of the upper part of the down frame 5, and the other radiator 43 is disposed on the left side of the upper part of the down frame 5. Each of the radiators 42, 43 is attached to the upper part of the down frame 5 via a radiator mount.

[0046] A step 44 for the right foot and a brake pedal 45 are provided at the bottom of the rear portion 4B of the right main frame 4 (see FIG. 2). A step 44 for the left foot and a shift pedal 46 are provided at the bottom of the rear portion 4B of the left main frame 4 (see FIG. 4). A seat 47 on which the driver sits is provided at the top of the middle portion in the fore-and-aft direction of the saddle riding type vehicle 1, and cowls 48 are provided in front of and behind the seat 47 (see FIG. 1).

[0047] (Exhaust pipes and silencers) The saddle-type vehicle 1 is provided with a silencer 51 that reduces the exhaust noise of exhaust gas discharged from the exhaust port 36 of the engine 31, and an exhaust pipe 60 that sends the exhaust gas discharged from the exhaust port 36 to the silencer 51.

[0048] The silencer 51 is disposed behind the engine 31, specifically, behind the air cleaner 40 which is disposed behind the engine 31 as shown in Fig. 1. The silencer 51 is disposed between the right seat rail 7 and the rear wheel 20 so that the outlet for discharging exhaust gas into the outside air faces rearward. The silencer 51 is supported by the right seat rail 7 via a stay.

[0049] The exhaust pipe 60 is a pipe that connects the exhaust port 36 formed in the cylinder head 34 of the engine 31 and the silencer 51, and is made of a metal material such as steel. As shown in Fig. 4, the exhaust pipe 60 has a first section 61 that extends downward from the exhaust port 36 to an area in front of the engine 31 and to the left of the down frame 5 (to one side in the left-right direction), a second section 62 that extends from the downstream end of the first section 61 through a lower-front area of ​​the down frame 5 to the right side of the down frame 5 (the other side in the left-right direction) and then extends upward through an area in front of the engine 31 and to the right of the down frame 5 (the other side in the left-right direction), as shown in Fig. 3, a third section 63 that extends rearward from the downstream end of the second section 62 to an area to the right of the engine 31, as shown in Fig. 2, and a fourth section 64 that extends from the downstream end of the third section 63 to the silencer 51, as shown in Fig. 1.

[0050] Figure 8 is a diagram showing the exhaust pipe 60, the silencer 51, and parts provided in the exhaust pipe 60 extracted from the saddle-riding vehicle 1. The dashed-dotted line K in Figure 8 is a line that passes through the center of the exhaust pipe 60. In the exhaust pipe 60 in Figure 8, the section from position a to position b is a first section 61, the section from position b to position c is a second section 62, the section from position c to position d is a third section 63, and the section from position c to position d is a fourth section.

[0051] Each part of the exhaust pipe 60 will be described in more detail. The upstream end of the first portion 61 of the exhaust pipe 60 is connected to the exhaust port 36, which opens to the front left, at a position toward the left of the front surface of the cylinder head 34. As shown in FIG. 3 , the first portion 61 of the exhaust pipe 60 is located to the left of the down frame 5. In a front view of the saddle-riding type vehicle 1, the first portion 61 of the exhaust pipe 60 extends from the exhaust port 36 downward and left, and then extends downward and right. In a front view of the saddle-riding type vehicle 1, the first portion 61 of the exhaust pipe 60 as a whole is gently curved so as to describe an arc-shaped path that bulges out to the left with the lower part of the down frame 5 as its diameter, and the upstream end and downstream end of the first portion 61 of the exhaust pipe 60 are close to the down frame 5, whereas the middle portion of the first portion 61 of the exhaust pipe 60 is distant from the down frame 5. Furthermore, the downstream end of the first portion 61 of the exhaust pipe 60 is located forward of the crankcase 32 and at the lower left and forward of the down frame 5. Specifically, the downstream end of the first portion 61 of the exhaust pipe 60 is located lower and left of the lower end of the down frame 5, and is located forward of the upper end portion of the left underframe 6 in a front view of the saddle-riding type vehicle 1. Furthermore, as shown in FIG. 4, in a left view of the saddle-riding type vehicle 1, the first portion 61 of the exhaust pipe 60 extends downward while inclining forward from the exhaust port 36, and the upstream end of the first portion 61 of the exhaust pipe 60 is located rearward of the down frame 5, but the downstream end of the first portion 61 of the exhaust pipe 60 is located forward of the down frame 5. Furthermore, as shown in FIG. 5, the middle portion of the first portion 61 of the exhaust pipe 60 protrudes to the left (outward in the left-right direction) of the left main frame 4, but is located to the right (inward in the left-right direction) of the leftmost portion of the engine 31 (the left surface of the magneto cover 39). The first portion 61 of the exhaust pipe 60 has a constant diameter over its entire length. The first portion 61 of the exhaust pipe 60 is formed by bending a pipe.

[0052] As shown in FIG. 3 , in a front view of the saddle-riding type vehicle 1, the second portion 62 of the exhaust pipe 60 extends from the downstream end of the first portion 61 of the exhaust pipe 60, which is located to the left of the down frame 5, to the right below and in front of the down frame 5, and then extends to the right of the lower part of the down frame 5 and to the upper right. The upstream portion of the second portion 62 of the exhaust pipe 60 is gently curved in an arc, and due to this curvature, the extending direction of the second portion 62 of the exhaust pipe 60 gradually changes from the right to the upper right. The upstream portion of the second portion 62 of the exhaust pipe 60 passes in front of the upper end portion of the right underframe 6. As shown in FIG. 2 , in a right view of the saddle-riding type vehicle 1, the middle portion of the second portion 62 of the exhaust pipe 60 extends to the upper rear below and to the right of the lower part of the down frame 5, and the downstream portion of the second portion 62 of the exhaust pipe 60 is curved so as to approach horizontal. Furthermore, the portion of the second portion 62 of the exhaust pipe 60 from the intermediate portion to the downstream portion extends in the vertical direction from approximately the middle of the crankcase 32, past the boundary between the crankcase 32 and the cylinder 33, to the boundary between the cylinder 33 and the cylinder head 34. Furthermore, the portion of the second portion 62 of the exhaust pipe 60 from the intermediate portion to the downstream portion extends in the longitudinal direction from a position forward of the down frame 5 to a position rearward of the down frame 5. Furthermore, as shown in FIG. 5 , in a top view of the saddle-riding type vehicle 1, the portion of the second portion 62 of the exhaust pipe 60 from the intermediate portion to the downstream portion is located right-front (outside) of the front portion 4A of the right main frame 4, and extends along the front portion 4A of the right main frame 4. Furthermore, the position of the downstream end of the second portion 62 of the exhaust pipe 60 in the vertical direction is approximately the same as the boundary between the cylinder 33 and the cylinder head 34, as shown in FIG. The position of the downstream end of the second portion 62 of the exhaust pipe 60 in the front-rear direction is approximately the same as the position of the front surface of the cylinder 33. The position of the downstream end of the second portion 62 of the exhaust pipe 60 in the left-right direction is to the right of the right surface of the cylinder 33 (outside in the left-right direction) and to the right of the right surface of the cylinder head 34, as shown in Fig. 3, and also to the right of the right main frame 4 but to the left of the rightmost part of the engine 31 (the rightmost part of the water pump 37) (inside in the left-right direction) as shown in Fig. 5.Furthermore, the second portion 62 of the exhaust pipe 60 is provided with a first catalyst device housing portion 73, as will be described later.

[0053] As shown in FIG. 2 , the third section 63 of the exhaust pipe 60 extends substantially horizontally rearward from the downstream end of the second section 62 of the exhaust pipe 60 to the right of the boundary between the cylinder 33 and the cylinder head 34. As shown in FIG. 5 , the upstream section of the third section 63 of the exhaust pipe 60 is located to the right of the front section 4A of the right main frame 4, but the downstream section of the third section 63 of the exhaust pipe 60 bends slightly to the right (inward in the left-right direction) after passing over the cylinder 33, and extends rearward by passing to the left (inward in the left-right direction) of the rear section 4B of the right main frame 4. The third section 63 of the exhaust pipe 60 has a constant diameter throughout its entire length. The diameter of the third section 63 of the exhaust pipe 60 is substantially equal to the diameter of the first section 61 of the exhaust pipe 60. The third section 63 of the exhaust pipe 60 is formed of a pipe. A heat shield 65 is provided to the right of the third portion 63 of the exhaust pipe 60 to prevent heat from the exhaust pipe 60 from being transmitted to the driver's right leg. The heat shield 65 covers a wide area of ​​the outer surface of the right portion of the third portion 63. The heat shield 65 is attached to the third portion 63 via a spacer or the like.

[0054] Furthermore, the fourth section 64 of the exhaust pipe 60 extends rearward from the downstream end of the third section 63 of the exhaust pipe 60, below the right section of the air cleaner 40. Furthermore, the upstream section of the fourth section 64 of the exhaust pipe 60 is formed integrally with the third section 63 of the exhaust pipe 60, and the section of the exhaust pipe 60 from the upstream end of the third section 63 to approximately the middle section of the fourth section 64 is formed by a single pipe. Furthermore, a second catalytic device housing 85 is provided in the downstream section of the fourth section 64 of the exhaust pipe 60, as will be described later. Furthermore, the downstream end of the fourth section 64 of the exhaust pipe 60 is connected to an inlet in the muffler 51 through which exhaust gas flows.

[0055] (catalytic device / catalytic device housing) The saddle-ride type vehicle 1 is equipped with two catalytic converters, namely a first catalytic converter 71 and a second catalytic converter 72, which purify the exhaust gas discharged from the exhaust port 36 of the engine 31 and flowing through the exhaust pipe 60. The first catalytic converter 71 and the second catalytic converter 72 are each a three-way catalyst, formed by supporting a catalyst on a monolithic carrier having a honeycomb structure, for example. The first catalytic converter 71 has a cylindrical outer shape, and its diameter is larger than the diameter of the first portion 61 of the exhaust pipe 60 and larger than the diameter of the third portion 63 of the exhaust pipe 60. The second catalytic converter 72 has a cylindrical outer shape, and its diameter is larger than the diameter of the upstream portion of the fourth portion 64 of the exhaust pipe 60.

[0056] The first catalytic converter 71 and the second catalytic converter 72 are both provided midway through the exhaust pipe 60. Specifically, as shown in FIGS. 2 and 3 , the first catalytic converter 71 is provided inside the second section 62 of the exhaust pipe 60. More specifically, the first catalytic converter 71 is provided inside a portion of the second section 62 of the exhaust pipe 60 that is located in front of the engine 31 and to the right of the down frame 5. The first catalytic converter 71 is also disposed in a position higher than the lower end of the down frame 5 and lower than the exhaust port 36 of the engine 31. The first catalytic converter 71 is also disposed above the underframe 6. On the other hand, the second catalytic converter 72 is provided inside a downstream portion of the fourth section 64 of the exhaust pipe 60, as shown in FIG. 1 . The first catalytic converter 71 is a specific example of a "catalytic converter" as defined in the claims.

[0057] The second section 62 of the exhaust pipe 60 is provided with a first catalytic device housing 73 that houses a first catalytic device 71. As shown in FIGS. 2 and 3 , the first catalytic device housing 73 has a cylindrical expanded diameter section 74 that expands in diameter from the upstream side to the downstream side of the second section 62 of the exhaust pipe 60, a cylindrical large diameter section 75 connected to the downstream end of the expanded diameter section 74, and a cylindrical reduced diameter section 76 that is connected to the downstream end of the large diameter section 75 and reduces in diameter from the upstream side to the downstream side of the second section 62 of the exhaust pipe 60. In this embodiment, the entire second section 62 forms the first catalytic device housing 73. That is, the upstream portion of the second section 62 of the exhaust pipe 60 is the expanded diameter section 74, the middle portion of the second section 62 of the exhaust pipe 60 is the large diameter section 75, and the downstream portion of the second section 62 of the exhaust pipe 60 is the reduced diameter section 76. The first catalyst device housing 73 is a specific example of a "catalyst device housing" in the claims.

[0058] The upstream end of the expanded diameter section 74 is connected to the downstream end of the first section 61 of the exhaust pipe 60. The downstream end of the reduced diameter section 76 is connected to the third section 63 of the exhaust pipe 60. The first catalytic device 71 is disposed inside the large diameter section 75 so that its axis coincides with the axis of the large diameter section 75.

[0059] The diameter of the large-diameter portion 75 is constant from its upstream end to its downstream end. The diameter of the large-diameter portion 75 is larger than the diameter of the first catalytic device 71. The diameter of the large-diameter portion 75 is also larger than the diameter of the first portion 61 of the exhaust pipe 60 and larger than the diameter of the third portion 63 of the exhaust pipe 60. For example, the diameter of the large-diameter portion 75 is set to a value slightly larger than the diameter of the first catalytic device 71 so that the first catalytic device 71 can be accommodated and fixed within the large-diameter portion 75. The diameter of the upstream end of the expanded-diameter portion 74 is equal to the diameter of the first portion 61 of the exhaust pipe 60, and the diameter of the downstream end of the expanded-diameter portion 74 is equal to the diameter of the large-diameter portion 75. The diameter of the upstream end of the reduced-diameter portion 76 is equal to the diameter of the large-diameter portion 75, and the diameter of the downstream end of the reduced-diameter portion 76 is equal to the diameter of the third portion 63 of the exhaust pipe 60.

[0060] The expanded diameter portion 74 extends from a region in front of the crankcase 32 and below the down frame 5 to a region in front of the crankcase 32 and to the right of the down frame 5, bending toward the upper right and rear while expanding in diameter. That is, as shown in FIG. 3 , the upstream end of the expanded diameter portion 74 is located in front of the crankcase 32 and at the lower left front of the down frame 5. Specifically, the upstream end of the expanded diameter portion 74 is located lower and left of the lower end of the down frame 5, and is located in front of the upper end portion of the left underframe 6 in a front view of the saddle-ride type vehicle 1. The expanded diameter portion 74 gradually expands in diameter while gently curving in an arc. The expanded diameter portion 74 also passes in front of the upper end portion of the right underframe 6. The downstream end of the expanded diameter portion 74 is located in front of the crankcase 32 and at the lower right front of the down frame 5.

[0061] The large diameter portion 75 extends linearly to the upper right and rear in an area in front of the crankcase 32 and to the right of the down frame 5. The large diameter portion 75 and the first catalytic device 71 in the large diameter portion 75 are located substantially directly to the right of the lower end portion of the down frame 5. The large diameter portion 75 and the first catalytic device 71 in the large diameter portion 75 are also located substantially directly below the radiator 42 on the right side.

[0062] The reduced diameter portion 76 extends from an area in front of the crankcase 32 and to the right of the down frame 5 toward an area to the right of the cylinder 33 or the cylinder head 34, bending rearward so as to approach horizontality and reducing in diameter. The reduced diameter portion 76 gradually reduces in diameter while gently curving like an arc. As shown in FIG. 2, the position of the downstream end of the reduced diameter portion 76 in the up-down direction is approximately equal to the position of the boundary between the cylinder 33 and the cylinder head 34, and the position of the downstream end of the reduced diameter portion 76 in the front-to-rear direction is approximately equal to the position of the front surface of the cylinder 33. As shown in FIG. 3, the position of the downstream end of the reduced diameter portion 76 in the left-right direction is to the right of (outside in the left-right direction) the right surface of the cylinder 33 and to the right of the right surface of the cylinder head 34, and also to the right of the right main frame 4 as shown in FIG. 5.

[0063] When the first catalytic converter housing 73 is viewed as a whole, the first catalytic converter housing 73 is inclined so that the downstream end of the reduced diameter portion 76 (the downstream end of the first catalytic converter housing 73) is located higher and rearward than the upstream end of the expanded diameter portion 74 (the upstream end of the first catalytic converter housing 73). The first catalytic converter housing 73 is also inclined so that the downstream end of the reduced diameter portion 76 is located higher and to the right of the upstream end of the expanded diameter portion 74. That is, as shown in FIG. 2 , the first catalytic converter housing 73 extends from a position forward of the down frame 5 to a position rearward of the down frame 5 in a right side view of the saddle-riding type vehicle 1. The first catalytic converter housing 73 also extends from approximately the middle of the crankcase 32, past the boundary between the crankcase 32 and the cylinder 33, to the boundary between the cylinder 33 and the cylinder head 34 in a right side view of the saddle-riding type vehicle 1. 3, the first catalytic converter housing 73 extends from a position to the left of the down frame 5 to a position to the right of the down frame 5 in a front view of the saddle-riding type vehicle 1. Furthermore, as shown in FIG. 5, the first catalytic converter housing 73 extends outward from the front portion 4A of the right main frame 4 so as to follow the front portion 4A of the right main frame 4 in a top view of the saddle-riding type vehicle 1.

[0064] In addition, in this embodiment, the rightmost portion of the first catalytic converter housing 73 is the right surface of the upstream portion of the reduced diameter portion 76. As can be seen from FIG. 3 or 6, the position of the rightmost portion of the first catalytic converter housing 73 is to the left of the rightmost portion of the engine 31 (the rightmost portion of the water pump 37) and to the left of the right surface of the clutch cover 38. In addition, in this embodiment, the bottommost portion of the first catalytic converter housing 73 is the underside of the middle portion of the expanded diameter portion 74. As can be seen from FIG. 2, the vertical position of the bottommost portion of the first catalytic converter housing 73 is approximately the same as the vertical position of the front end of the brake pedal 45 or the step 44.

[0065] The first catalytic converter housing 73 is disposed below the right radiator 42 and tilted in the front-to-rear direction so that the upstream end of the expanded diameter portion 74 is forward of the front surface of the right radiator 42 and the downstream end of the reduced diameter portion 76 is rearward of the rear surface of the right radiator 42. The rightmost portion of the first catalytic converter housing 73 is to the left of the right surface of the right radiator 42.

[0066] The lower left part of Fig. 8 illustrates the first catalytic converter housing 73 in an exploded state. The first catalytic converter housing 73 has a monaka (a square-shaped) structure and is formed by joining, for example, four metal plates 77-80, as shown in the lower left part of Fig. 8. In this embodiment, the expanded diameter portion 74 is formed by welding together two press-formed metal plates 77, 78. A structure in which the large diameter portion 75 and the reduced diameter portion 76 are integrated is formed by welding together two press-formed metal plates 79, 80. The first catalytic converter housing 73 is formed by welding together the expanded diameter portion 74 and the integrated structure in which the large diameter portion 75 and the reduced diameter portion 76 are integrated. The first catalytic converter 71 is sandwiched between the two metal plates 79, 80. Also, for example, the upstream end of the expanded diameter portion 74 of the first catalytic device housing portion 73 is welded to the downstream end of the first part 61 of the exhaust pipe 60, and the downstream end of the reduced diameter portion 76 of the first catalytic device housing portion 73 is welded to the upstream end of the third part 63 of the exhaust pipe 60.

[0067] A second catalytic converter housing 85 is provided in the downstream portion of the fourth portion 64 of the exhaust pipe 60. The second catalytic converter housing 85 is formed in a cylindrical shape with a diameter larger than the diameter of the second catalytic converter 72 and the diameter of the upstream portion of the fourth portion 64 of the exhaust pipe 60. The second catalytic converter 72 is provided inside the second catalytic converter housing 85.

[0068] Furthermore, a first exhaust gas sensor 91 is provided in the exhaust pipe 60 upstream of the first catalytic device 71, and a second exhaust gas sensor 92 is provided downstream of the first catalytic device 71. The first exhaust gas sensor 91 is a sensor, such as an oxygen sensor, that detects the state of exhaust gas inside a portion of the exhaust pipe 60 upstream of the first catalytic device 71. The second exhaust gas sensor 92 is a sensor, such as an oxygen sensor, that detects the state of exhaust gas inside a portion of the exhaust pipe 60 downstream of the first catalytic device 71. In order to increase the purification rate of exhaust gas by the first catalytic device 71, the saddle-riding type vehicle 1 performs fuel injection control and the like based on the detection signals output from the first exhaust gas sensor 91 and the second exhaust gas sensor 92. The first exhaust gas sensor 91 is a specific example of an "exhaust gas sensor" in the claims.

[0069] The first exhaust gas sensor 91 is provided in a portion of the exhaust pipe 60 that passes through the area in front of the down frame 5. Specifically, as shown in FIG. 3 , the first exhaust gas sensor 91 is provided in a downstream portion of the first section 61 of the exhaust pipe 60, and is provided so as to protrude upper right and rearward from the upper surface of the downstream portion of the first section 61. Furthermore, the first exhaust gas sensor 91 is disposed so that the entire first exhaust gas sensor 91 overlaps with the first catalytic converter housing 73 in a side view of the saddle riding type vehicle 1. As shown in FIG. 2 , the first exhaust gas sensor 91 is completely hidden by the first catalytic converter housing 73 in a right view of the saddle riding type vehicle 1. Furthermore, the first exhaust gas sensor 91 is disposed so that the entire first exhaust gas sensor 91 overlaps with the first section 61 of the exhaust pipe 60 in a side view of the saddle riding type vehicle 1. As shown in FIG. 4 , the first exhaust gas sensor 91 is completely hidden by the first section 61 of the exhaust pipe 60 in a left view of the saddle riding type vehicle 1. 3, the first exhaust gas sensor 91 is disposed so as to overlap with the upper end portion of the left underframe 6 when viewed from the front of the saddle riding type vehicle 1. As shown in FIG.

[0070] The second exhaust gas sensor 92 is provided in the upstream portion of the third section 63 of the exhaust pipe 60, and is provided so as to protrude upward from the upper surface of the upstream portion of the third section 63. The second exhaust gas sensor 92 is located to the right of the cylinder head 34, and the entire second exhaust gas sensor 92 overlaps with the cylinder head 34 in a side view of the saddle-riding type vehicle 1.

[0071] As described above, in the saddle-ride type vehicle 1 according to the embodiment of the present invention, the exhaust pipe 60 has a first section 61 that extends downward from the exhaust port 36 of the engine 31 through a region forward of the engine 31 and to the left of the down frame 5, a second section 62 that extends from the downstream end of the first section 61 through a region below and forward of the down frame 5 to the right of the down frame 5 and then extends upward through a region forward of the engine 31 and to the right of the down frame 5, a third section 63 that extends rearward from the downstream end of the second section 62 through a region to the right of the engine 31, and a fourth section 64 that extends from the downstream end of the third section 63 to the muffler 51. The first catalytic device 71 is disposed inside a portion of the second section 62 of the exhaust pipe 60 that is located forward of the engine 31 and to the right of the down frame 5. This allows the first catalytic device 71 to be appropriately provided inside the front portion of the exhaust pipe 60.

[0072] That is, in conventional saddle-ride type vehicles in which the exhaust pipe passes along the side of the engine, the length of the exhaust pipe from the engine exhaust port to the side of the engine is short, making it difficult to install a catalytic converter in this section. However, the exhaust pipe 60 of the saddle-ride type vehicle 1 of this embodiment has a first section 61 that extends downward from the exhaust port 36 to a region forward of the engine 31 and to the left of the down frame 5, and a second section 62 that extends from the downstream end of the first section 61 through a region below and forward of the down frame 5 to the right of the down frame 5, and then extends upward through a region forward of the engine 31 and to the right of the down frame 5. With this configuration, a sufficient length of pipe can be ensured in the section of the exhaust pipe 60 located forward of the engine 31 and to the right of the down frame 5, making it easy to install the first catalytic converter 71 in this section. In particular, a large first catalytic device 71 having a diameter larger than the diameter of either the first portion 61 or the third portion 63 of the exhaust pipe 60 and having a high exhaust gas purification capacity can be easily installed in a portion of the exhaust pipe 60 located in front of the engine 31 and to the right of the down frame 5.

[0073] To explain in more detail, by designing the path of the exhaust pipe 60 to run from the left side of the down frame 5, pass below and in front of the down frame 5, and reach the right side of the down frame 5, the orientation of the second portion 62 of the exhaust pipe 60 at the lower right of the down frame 5 can be made closer to a vertically upward direction in a front view of the saddle-riding type vehicle 1, without increasing the curvature of the curve of the upstream portion of the second portion 62 of the exhaust pipe 60. This makes it possible to extend the second portion 62 of the exhaust pipe 60 a long distance in a straight line from the lower right of the down frame 5 to the right front of the cylinder 33 of the engine 31, and also makes it possible to prevent the downstream end portion of the second portion 62 of the exhaust pipe 60 from protruding rightward from the rightmost part of the engine 31. As a result, in the second part 62 of the exhaust pipe 60, a large diameter section 75 extending linearly is provided in the part extending linearly from the lower right of the down frame 5 to the front right of the cylinder 33, and it becomes possible to accommodate a large first catalytic device 71 that has a large diameter and is somewhat long in the axial direction inside this large diameter section 75, and it becomes possible to position the first catalytic device accommodation section 73 that accommodates such a large first catalytic device 71 so that it does not protrude from the rightmost part of the engine 31 when viewed from the front of the saddle-type vehicle 1.

[0074] In a conventional saddle-type vehicle having an exhaust pipe that passes beside the engine, if a catalytic converter with a diameter larger than the normal diameter of the exhaust pipe is provided inside the portion of the exhaust pipe that passes beside the engine, the portion between the right and left legs of the driver seated on the seat of the saddle-type vehicle becomes wider, which can lead to a problem of poor driving posture for the driver. Furthermore, even if a catalytic converter with a diameter smaller than the normal diameter of the exhaust pipe is provided inside the portion of the exhaust pipe that passes beside the engine, it is necessary to increase the distance between the exhaust pipe and the shielding plate to protect the driver's legs from the heat from the exhaust pipe, which can lead to a problem of poor driving posture for the driver. However, in the saddle-type vehicle 1 of this embodiment, the first catalytic converter 71 is provided inside the second portion 62 of the exhaust pipe 60, in a portion that is located forward of the engine 31 and to the right of the down frame 5, so this problem does not arise. In other words, the saddle-type vehicle 1 of this embodiment can prevent the driver's driving posture from being poorly adjusted due to the provision of the first catalytic converter 71 inside the front portion of the exhaust pipe 60.

[0075] Furthermore, as mentioned above, in the saddle-riding vehicle described in JP 2008-64068 A (Patent Document 1), by providing a catalytic device with a diameter larger than the normal diameter of the exhaust pipe inside the portion of the exhaust pipe that passes closer to the center of the saddle-riding vehicle in the left-right direction than the engine cylinder or cylinder head and extends rearward, it becomes necessary to expand the space surrounded by the main frame, rear cushion, engine cylinder, etc., which could result in a problem that the saddle-riding vehicle becomes larger. However, because the first catalytic device 71 of the saddle-riding vehicle 1 of this embodiment is located inside the portion of the second portion 62 of the exhaust pipe 60 that is located forward of the engine 31 and to the right of the down frame 5, this problem does not arise.

[0076] Furthermore, in the saddle-ride type vehicle 1 of this embodiment, the exhaust port 36 of the engine 31 is disposed in front of the cylinder head 34 and opens forward while tilting to the left. This allows the exhaust pipe 60 to be easily connected to the exhaust port 36 without providing a portion at the upstream end side (first portion 61) of the exhaust pipe 60 that locally bends with a large curvature. Furthermore, the exhaust pipe 60 can be extended from the exhaust port 36 to a position below and forward of the down frame 5 without providing a portion at the upstream end side (first portion 61) of the exhaust pipe 60 that bends in a complex manner, such as an S-shape or crank-shape. Furthermore, if the exhaust port 36 of the engine 31 opens forward without tilting to the left or right and the down frame 5 is located beyond the opening direction of the exhaust port 36, a space must be secured between the front of the engine 31 and the down frame 5 in order to position the upstream end side of the exhaust pipe 60. However, in this embodiment, the exhaust port 36 of the engine 31 opens forward while tilting to the left, so the opening direction of the exhaust port 36 can be deviated from the down frame 5, and therefore the upstream end portion of the exhaust pipe 60 can be disposed without ensuring such a distance. Therefore, the distance between the front portion of the engine 31 and the down frame 5 can be reduced, and the saddle-riding type vehicle 1 can be made more compact. Furthermore, because the exhaust port 36 of the engine 31 opens forward while tilting to the left, it is possible to prevent the first portion 61 of the exhaust pipe 60 from protruding leftward beyond the leftmost portion of the engine 31.

[0077] Furthermore, in the saddle-ride type vehicle 1 of this embodiment, the first catalytic device 71 is disposed in front of the engine 31 and to the right of the down frame 5, at a position higher than the lower end of the down frame 5 and lower than the exhaust port 36 of the engine 31. Because the first catalytic device 71 is disposed at a position higher than the lower end of the down frame 5, it is possible to prevent the bottom surface of the second portion 62 of the exhaust pipe 60 from becoming lower. Therefore, even if the front wheel 16 goes over a large stone on uneven ground or a step on the road, causing the front fork 15 to retract and the front wheel 16 to move in a direction approaching the front fender 17, it is possible to prevent the front wheel 16 from contacting the second portion 62 of the exhaust pipe 60. Furthermore, because the first catalytic device 71 is disposed at a position lower than the exhaust port 36 of the engine 31, it is possible to prevent the top surface of the second portion 62 of the exhaust pipe 60 from becoming higher, and it is possible to keep the second portion 62 of the exhaust pipe 60 sufficiently away from parts of the body of the rider seated on the seat 47.

[0078] Furthermore, in the saddle-type vehicle 1 of this embodiment, the second portion 62 of the exhaust pipe 60 is provided with a first catalytic device housing portion 73 having an expanded diameter portion 74, a large diameter portion 75, and a reduced diameter portion 76. This allows a large first catalytic device 71, whose diameter is larger than both the diameters of the first portion 61 and the third portion 63 of the exhaust pipe 60 and which has a high exhaust gas purification capacity, to be provided in the second portion 62 of the exhaust pipe 60.

[0079] Furthermore, in the saddle-ride type vehicle 1 of this embodiment, the first catalytic converter housing 73 is inclined so that the downstream end of the reduced diameter portion 76 is located above and to the rear of the upstream end of the expanded diameter portion 74. This allows the curvature of the reduced diameter portion 76 to be small. The first catalytic converter housing 73 is inclined so that the downstream end of the reduced diameter portion 76 is located above and to the right of the upstream end of the expanded diameter portion 74. This allows the curvature of the expanded diameter portion 74 to be small. Furthermore, by inclining the first catalytic converter housing 73 so that the downstream end of the reduced diameter portion 76 is located above, to the rear, and to the right of the upstream end of the expanded diameter portion 74, the first catalytic converter housing 73, which can accommodate a large first catalytic converter 71, can be arranged in a region from the lower front of the down frame 5 to the right of the down frame 5, without forming a locally curved portion with a large curvature in the first catalytic converter housing 73. Furthermore, by tilting the first catalytic device housing portion 73 in this manner, the first catalytic device housing portion 73 can be located in front of the engine 31 and to the right of the down frame 5, while still preventing the saddle-type vehicle 1 from becoming larger.

[0080] Furthermore, in the saddle-ride type vehicle 1 of this embodiment, the expanded diameter portion 74 extends from a region in front of the crankcase 32 and below the front of the down frame 5 to a region in front of the crankcase 32 and to the right of the down frame 5, while bending and widening in diameter upward and rearward. This configuration makes it possible to easily connect, via the expanded diameter portion 74, the downstream end of the first section 61 of the exhaust pipe 60, which is located below and to the left of the lower end of the down frame 5, to the large diameter portion 75 of the first catalytic converter housing 73, which is located to the right of the down frame 5, higher than the lower end of the down frame 5, and lower than the exhaust port 36 of the engine 31, and which has a larger diameter than the downstream end of the first section 61 of the exhaust pipe 60. Furthermore, by forming the first catalytic converter housing 73 in a bunaka structure, it is possible to easily manufacture the expanded diameter portion 74, which is curved and widens in diameter.

[0081] Furthermore, in the saddle-ride type vehicle 1 of this embodiment, the reduced diameter portion 76 extends from an area in front of the crankcase 32 and to the right of the down frame 5 toward an area to the right of the boundary between the cylinder 33 and the cylinder head 34, while bending rearward so as to approach horizontality and while reducing in diameter. With this configuration, it is possible to easily connect, via the reduced diameter portion 76, the large diameter portion 75 of the first catalytic converter housing 73, which is disposed to the right of the down frame 5, higher than the lower end of the down frame 5, and lower than the exhaust port 36 of the engine 31, and which has a larger diameter than the upstream end of the third section 63 of the exhaust pipe 60, to the upstream end of the third section 63 of the exhaust pipe 60, which is located to the right of the boundary between the cylinder 33 and the cylinder head 34. Furthermore, by forming the first catalytic converter housing 73 in a bunaka structure, it is possible to easily manufacture the reduced diameter portion 76, which is curved and reduces in diameter.

[0082] Furthermore, in the saddle-ride type vehicle 1 of this embodiment, the first catalytic converter housing 73 is disposed below the right radiator 42 in a longitudinally inclined state so that the upstream end of the enlarged diameter portion 74 is forward of the front surface of the right radiator 42 and the downstream end of the reduced diameter portion 76 is rearward of the rear surface of the right radiator 42. This allows a radiator with a large vertical dimension and therefore a large core area to be used as the right radiator 42. This increases the cooling capacity of the radiator 42. In other words, if the first catalytic converter housing 73 were disposed vertically below the right radiator 42, a radiator with a small vertical dimension and therefore a small core area would have to be used as the right radiator 42 to avoid contact between the downstream end of the reduced diameter portion 76 provided at the top of the first catalytic converter housing 73 and the lower end of the right radiator 42. In contrast, in the saddle-ride type vehicle 1 of this embodiment, the first catalytic converter housing 73 is inclined so that the downstream end of the reduced diameter portion 76 is located further rearward than the rear surface of the right radiator 42. Therefore, even if the lower end of the right radiator 42 is located below the reduced diameter portion 76 of the first catalytic converter housing 73, contact between the lower end of the right radiator 42 and the first catalytic converter housing 73 can be avoided (for example, the lower end of the right radiator 42 can be extended downward to just before the large diameter portion 75 of the inclined first catalytic converter housing 73). Therefore, a radiator with a large vertical dimension and therefore a large core area can be used as the right radiator 42. Furthermore, if a radiator with a small vertical dimension is used as the right radiator 42, the right radiator 42 can be spaced apart from the first catalytic converter housing 73, making it difficult for radiant heat from the first catalytic converter housing 73 to be transmitted to the right radiator 42.

[0083] Furthermore, in the saddle-riding vehicle 1 of this embodiment, the first exhaust gas sensor 91 is provided in a portion of the exhaust pipe 60 that passes through the area in front of the down frame 5, and is disposed so that the entirety of the first exhaust gas sensor 91 overlaps with the first catalytic converter housing 73 in a side view of the saddle-riding vehicle 1. Because the first exhaust gas sensor 91 is provided in a portion of the exhaust pipe 60 that passes through the area in front of the down frame 5, the first exhaust gas sensor 91 can be easily attached to and detached from the exhaust pipe 60. Furthermore, because the first exhaust gas sensor 91 is disposed so that the entirety of the first exhaust gas sensor 91 overlaps with the first catalytic converter housing 73 in a side view of the saddle-riding vehicle 1, the first catalytic converter housing 73 can function as a partition that prevents flying stones from the right from hitting the first exhaust gas sensor 91, and the first exhaust gas sensor 91 can be protected by the first catalytic converter housing 73. Furthermore, in the saddle-riding vehicle 1 of this embodiment, the first exhaust gas sensor 91 is disposed so that the entire first exhaust gas sensor 91 overlaps with the first portion 61 of the exhaust pipe 60 in a side view of the saddle-riding vehicle 1. This allows the first portion 61 of the exhaust pipe 60 to function as a partition that prevents flying stones from the left from hitting the first exhaust gas sensor 91, and the first portion 61 of the exhaust pipe 60 can protect the first exhaust gas sensor 91.

[0084] Furthermore, in the saddle-type vehicle 1 of this embodiment, the first catalytic device housing 73 is located to the left of the rightmost part of the engine 31, and the first part 61 of the exhaust pipe 60 is located to the right of the leftmost part of the engine 31, so that the size of the saddle-type vehicle 1 can be prevented from increasing.

[0085] In the above embodiment, the second portion 62 of the exhaust pipe 60 (the expanded diameter portion 74 of the first catalytic device housing portion 73) extends from the downstream end of the first portion 61 of the exhaust pipe 60 through a lower front region of the down frame 5 to the right side of the down frame 5. However, when the present invention is applied to a saddle-ride type vehicle having a long down frame 5, the second portion 62 of the exhaust pipe 60 (the expanded diameter portion 74 of the first catalytic device housing portion 73) may also extend from the downstream end of the first portion 61 of the exhaust pipe 60 through a front region of the down frame 5 to the right side of the down frame 5.

[0086] Furthermore, in the above embodiment, the entire second portion 62 of the exhaust pipe 60 serves as the first catalytic device housing 73. However, the present invention is not limited to this, and a portion of the second portion 62 of the exhaust pipe 60 may serve as the first catalytic device housing 73. For example, the first catalytic device housing 73 may be provided so that the upstream end of the expanded diameter portion 74 of the first catalytic device housing 73 is located in a portion of the second portion 62 of the exhaust pipe 60 that is located to the right front or to the right and below front of the lower end of the down frame 5.

[0087] In the above embodiment, the first catalytic device 71 is disposed at a position higher than the lower end of the down frame 5. However, when the present invention is applied to a saddle-ride type vehicle having a short down frame 5, the first catalytic device 71 may be disposed so that the lower end of the first catalytic device 71 is lower than the lower end of the down frame 5.

[0088] The present invention can also be applied to a saddle-ride type vehicle that is not equipped with the second catalytic converter 72. The present invention can also be applied to a saddle-ride type vehicle that is not equipped with the first exhaust gas sensor 91 or the second exhaust gas sensor 92. The present invention can also be applied to a saddle-ride type vehicle that is not equipped with the left or right radiator 42.

[0089] Furthermore, the saddle-type vehicle of the present invention may have a configuration in which the engine exhaust port opens forward while tilting to the right, and the exhaust pipe has a first portion extending downward from the engine exhaust port through an area in front of the engine and to the right of the down frame, a second portion extending from the downstream end of the first portion through an area in front of or below-front of the down frame to the left side of the down frame and then extending upward through an area in front of the engine and to the left of the down frame, a third portion extending rearward from the downstream end of the second portion through an area to the left of the engine, and a fourth portion extending from the downstream end of the third portion to the muffler, and the catalytic device is disposed inside a portion of the second portion of the exhaust pipe that is located in front of the engine and to the left of the down frame.

[0090] Furthermore, in the above embodiment, the first catalytic device 71, whose diameter is larger than the diameters of both the first portion 61 and the third portion 63 of the exhaust pipe 60, is provided in the second portion 62 of the exhaust pipe 60. However, the present invention is not limited to this, and a catalytic device whose diameter is equal to the diameter of either the first portion 61 or the third portion 63 of the exhaust pipe 60, or a catalytic device whose diameter is smaller than the diameters of both the first portion 61 and the third portion 63 of the exhaust pipe 60, may be provided in the second portion 62 of the exhaust pipe 60. When a catalytic device whose diameter is smaller than the diameters of both the first portion 61 and the third portion 63 of the exhaust pipe 60 is provided in the second portion 62 of the exhaust pipe 60, the diameters of the first portion 61, the second portion 62, and the third portion 63 of the exhaust pipe 60 can be made equal, and in this case, the first catalytic device housing 73 having the expanded diameter portion 74, the large diameter portion 75, and the reduced diameter portion 76 does not need to be provided in the second portion 62 of the exhaust pipe 60.

[0091] Furthermore, in the above embodiment, the saddle-ride type vehicle 1 in which the third portion 63 of the exhaust pipe 60 passes to the right of the boundary between the cylinder 33 and the cylinder head 34 of the engine 31 is given as an example of a saddle-ride type vehicle having a structure in which the exhaust pipe passes beside the engine instead of below it, but the present invention is not limited to this. The present invention can also be applied to saddle-ride type vehicles in which the exhaust pipe passes to the side of the top of the engine crankcase, to the side of the cylinder, or to the side of the cylinder head.

[0092] The present invention is not limited to saddle-ride vehicles for off-road racing, but can also be applied to saddle-ride vehicles designed for both on-road and off-road driving. Furthermore, if there is a saddle-ride vehicle designed exclusively for on-road driving but with an exhaust pipe that passes to the side of the engine, the present invention can also be applied to such a saddle-ride vehicle.

[0093] Furthermore, the present invention can be modified as appropriate within the scope of the claims and the entire specification without departing from the gist or concept of the invention, and saddle-type vehicles incorporating such modifications are also included in the technical concept of the present invention. [Explanation of symbols]

[0094] 1. Saddle-type vehicle 3 Head pipe 4. Mainframe 5 Down Frame 31 Engine 32 Crankcase 33 cylinders 34 Cylinder head 36 Exhaust port 42 Radiator 51 Silencer 60 Exhaust pipe 61 Part 1 62 Part 2 63 Part 3 64 Part 4 71 First catalyst device (catalyst device) 73 First catalytic converter housing (catalytic converter housing) 74 Expanded diameter part 75 Large diameter section 76 Reduced diameter part 91 First exhaust gas sensor (exhaust gas sensor)

Claims

1. Head pipe and a main frame extending rearward from the head pipe; a down frame extending downward from the head pipe; an engine having a crankcase, a cylinder provided above the crankcase, and a cylinder head provided above the cylinder, the engine being disposed below the main frame and behind the down frame; a silencer disposed at the rear of the engine to reduce exhaust noise of exhaust gases discharged from an exhaust port provided in the cylinder head; an exhaust pipe connecting the exhaust port and the muffler and sending exhaust gas discharged from the exhaust port to the muffler; a catalytic converter provided in the exhaust pipe and configured to purify the exhaust gas flowing through the exhaust pipe, The exhaust port is disposed in a front portion of the cylinder head, and opens forward while tilting to one side in the left-right direction. the exhaust pipe has a first portion extending downward from the exhaust port through a region in front of the engine and on one side of the down frame in the left-right direction; a second portion extending from a downstream end of the first portion through a front or lower-front region of the down frame to the other side of the down frame in the left-right direction, and then extending upward through a region in front of the engine and on the other side of the down frame in the left-right direction; a third portion extending rearward from the downstream end of the second portion through a region on the other side of the engine in the left-right direction; and a fourth portion extending from the downstream end of the third portion to reach the muffler, the catalytic converter is disposed inside a portion of the second section of the exhaust pipe that is located in front of the engine and on the other lateral side of the down frame in the left-right direction, and that is higher than a lower end of the down frame and lower than the exhaust port.

2. a catalytic converter housing portion is provided in the second portion of the exhaust pipe, The catalyst device housing section is a cylindrical expanding portion whose diameter expands from the upstream side to the downstream side of the second portion; a cylindrical large diameter portion connected to a downstream end of the expanded diameter portion; a cylindrical reduced diameter portion connected to a downstream end of the large diameter portion and having a diameter reduced from the upstream side to the downstream side of the second portion, 2. The straddle-type vehicle according to claim 1, wherein the catalytic converter is disposed inside the large diameter portion.

3. 3. The straddle-type vehicle according to claim 2, wherein the catalytic converter housing is inclined so that a downstream end of the catalytic converter housing is positioned higher and rearward than an upstream end of the catalytic converter housing.

4. 4. The saddle-ride type vehicle according to claim 3, wherein the catalytic converter housing is inclined so that a downstream end of the catalytic converter housing is positioned higher than an upstream end of the catalytic converter housing and on the other side in the left-right direction.

5. 5. The saddle-ride type vehicle according to claim 3, wherein the expanded diameter portion extends from a region in front of the crankcase and in front or lower-front of the down frame to a region in front of the crankcase and on the other lateral side of the down frame in the left-right direction, bending upward and rearward while expanding in diameter.

6. 5. The saddle-ride type vehicle according to claim 3, wherein the reduced diameter portion extends from a region in front of the crankcase and on the other lateral side of the down frame toward a region on the other lateral side of the cylinder or the cylinder head in the lateral direction, while bending rearward so as to approach horizontal and reducing in diameter.

7. a heat exchanger provided on the other side of the upper portion of the down frame in the left-right direction, 5. The straddle-type vehicle according to claim 3, wherein the catalytic converter housing is disposed below the heat exchanger in a state inclined in the fore-and-aft direction so that an upstream end of the catalytic converter housing is forward of a front surface of the heat exchanger and a downstream end of the catalytic converter housing is rearward of a rear surface of the heat exchanger.

8. an exhaust gas sensor that detects the state of the exhaust gas inside a portion of the exhaust pipe upstream of the catalytic converter; 5. A saddle-ride type vehicle according to claim 2, wherein the exhaust gas sensor is provided in a portion of the exhaust pipe that passes through a region in front of the down frame, and the exhaust gas sensor is positioned so that the entirety of the exhaust gas sensor overlaps the catalytic converter housing portion in a side view of the saddle-ride type vehicle.

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