Straddled vehicle

Abstract

A straddled vehicle (1) is equipped with an EGR cooler (20) that is provided so that condensed water generated by cooling the exhaust gas is discharged from an exhaust-side port (21) and flows toward an exhaust path (12). At least a part of the EGR cooler is formed integrally with a cylinder part (3). A first bolt (33a) is one of a plurality of bolts (33) used for connecting the cylinder part and two frame parts (31) respectively disposed on the left part and the right part of the straddled vehicle, and the first bolt has a center axis line (Cb) along the left-right direction of the vehicle. In a first cross-section (X1a-X1p) that passes through the central axis (Cb) and is parallel to the central axis (Cb), at least a portion of the EGR cooler is disposed between two planes (SF1, SF2) that are orthogonal to the central axis (Cb) and respectively pass through the left end and the right end on the first cross-section of a first screw fastening structure (35) composed of the first bolt and a first screw hole (34) into which the first bolt is inserted.

Description

Straddled Vehicle

[0001] The present invention relates to a straddled vehicle having an EGR cooler.

[0002] Conventionally, an EGR (Exhaust Gas Recirculation) path that recirculates a portion of exhaust gas generated in an engine from the exhaust path to the intake path may be provided with an EGR cooler to cool the exhaust gas. For example, Patent Document 1 (JP-A-2005-102626) describes a motorcycle in which an EGR cooler is integrally provided in a gearbox housing. In the EGR cooler of Patent Document 1, the exhaust-side port through which the exhaust gas flows is located lower than the intake-side port through which the exhaust gas flows out. As a result, it is estimated that condensed water generated in the EGR cooler when the exhaust gas is cooled in the EGR cooler is discharged from the exhaust-side port and flows toward the exhaust path.

[0003] German Patent Application Publication No. 102018120800

[0004] Unlike automobiles, straddled vehicles have a characteristic in which the engine is connected to two frame sections located on the left and right sides of the vehicle, thereby functioning as a member that contributes to the rigidity of the vehicle body frame. Furthermore, straddled vehicles are smaller than automobiles and have less free space, which places restrictions on the placement of the EGR cooler. Furthermore, as in Patent Document 1, in order to direct condensed water generated in the EGR cooler toward the exhaust passage, strict restrictions are placed on the placement of the EGR cooler. There is a need to provide an EGR cooler in a straddled vehicle with a configuration different from that of Patent Document 1, which is restricted in its placement position in order to direct condensed water generated in the EGR cooler toward the exhaust passage while allowing the engine to function as a member that contributes to the rigidity of the vehicle body frame.

[0005] The present invention aims to provide a straddled vehicle in which the EGR cooler, whose placement position is restricted in order to channel condensed water generated within the EGR cooler toward the exhaust passage, is configured in a different manner from that of Patent Document 1, and in which the engine functions as a member that contributes to the rigidity of the vehicle frame.

[0006] (1) A straddled vehicle according to one embodiment of the present invention has the following configuration: A straddled vehicle equipped with an EGR cooler that is provided in an EGR path that recirculates a portion of exhaust gas generated in an engine from the exhaust path to the intake path, has an exhaust-side port through which the exhaust gas flows in and an intake-side port through which the exhaust gas flows out, and is configured so that a lower end of the exhaust-side port is located lower than the intake-side port in the vertical direction of the vehicle, cools the exhaust gas, and condensed water produced by the cooling of the exhaust gas is discharged from the exhaust-side port and flows toward the exhaust path, wherein the engine functions as a member that contributes to the rigidity of a body frame, (i) at least a portion of the EGR cooler is formed integrally with a cylinder portion that is included in the engine and is composed of a cylinder head portion and a cylinder body portion, and (ii) In a first cross section passing through the central axis of a first bolt, which is one of a plurality of bolts used to connect the cylinder section and two frame sections included in the body frame and located respectively on the left and right sides of the straddled vehicle without the use of a vibration absorbing member, along the left-right direction of the vehicle, and parallel to the central axis, at least a portion of the EGR cooler is arranged between two planes that pass through the left and right ends, respectively, on the first cross section of a first screw fastening structure consisting of the first bolt and a first screw hole into which the first bolt is inserted, and are perpendicular to the central axis of the first bolt.

[0007] According to this configuration, the EGR cooler is arranged so that condensed water generated by cooling the exhaust gas is discharged from the exhaust-side port and flows toward the exhaust path. The EGR cooler has the following two configurations so that the engine functions as a member contributing to the rigidity of the vehicle body frame. First, at least a portion of the EGR cooler is integrally formed with a cylinder section included in the engine and consisting of a cylinder head section and a cylinder body section. Second, at least a portion of the EGR cooler is arranged between two planes that pass through the left and right ends of the first bolt and the first screw fastening structure, respectively, on the first cross section and are perpendicular to the central axis of the first bolt, and that pass through the left and right ends of the first bolt and the first screw hole on the first cross section. The first bolt is one of multiple bolts used to connect two frame sections, located on the left and right sides of the straddled vehicle, to the cylinder section without using a vibration-absorbing member. In this way, the EGR cooler is installed using the cylinder section and the space surrounding the first screw fastening structure around the central axis of the first bolt, which is used to connect the frame section and the cylinder section. Therefore, although the EGR cooler is installed using the cylinder section, an increase in the vehicle's left-right length of the portion including the cylinder section and the EGR cooler can be suppressed. Therefore, the EGR cooler can be installed without affecting the function of the first screw fastening structure, and restrictions on the EGR cooler's placement can be alleviated. In this way, restrictions on the EGR cooler's placement can be alleviated without affecting the function of the first screw fastening structure, and the EGR cooler can be installed in a position where condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame by the engine. Therefore, an EGR cooler whose placement is restricted in order to allow condensed water generated in the EGR cooler to flow toward the exhaust passage can be installed in a straddled vehicle in which the engine functions as a member that contributes to the rigidity of the body frame, using a configuration different from that of Patent Document 1.

[0008] (2) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to the configuration described in (1) above: at least a portion of the EGR cooler is integrally formed with at least a portion of the cylinder section made of aluminum or an aluminum alloy so that the engine functions as a member that contributes to the rigidity of the body frame, and at least a portion of the EGR cooler is disposed between the two planes that pass through the left and right ends of the first screw fastening structure on the first cross section and are perpendicular to the central axis of the first bolt.

[0009] According to this configuration, the portion of the EGR cooler integrally formed with the cylinder portion is made of aluminum or an aluminum alloy. Aluminum has a high thermal conductivity, which allows heat from exhaust gases inside the EGR cooler to dissipate easily. Since the EGR cooler's cooling performance can be maintained while preventing its size from increasing, restrictions on the EGR cooler's placement location can be further alleviated. Furthermore, aluminum's excellent workability makes it easy to form at least a portion of the EGR cooler integrally with the cylinder portion, thereby improving design freedom for the EGR cooler. Since the increase in the lateral length of the engine portion including the cylinder portion and the EGR cooler can be further alleviated, restrictions on the EGR cooler's placement location can be further alleviated. Therefore, the EGR cooler can be positioned so that condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame due to the engine, without affecting the function of the first screw fastening structure.

[0010] (3) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to the configuration described in (1) or (2) above: an upper portion of a central axis of at least one cylinder bore formed by the cylinder portion is located forward of a lower portion in the vehicle longitudinal direction, a front portion of the cylinder portion forms part of the exhaust path, and a rear portion of the cylinder portion forms part of the intake path, at least a portion of the EGR cooler is formed integrally with the cylinder portion so that the engine functions as a member that contributes to the rigidity of the body frame, the exhaust-side opening of the EGR cooler is located forward of the intake-side opening in the vehicle longitudinal direction, and at least a portion of the EGR cooler is disposed between the two planes that pass through the left and right ends of the first screw fastening structure on the first cross section, respectively, and are perpendicular to the central axis of the first bolt.

[0011] According to this configuration, the upper portion of the central axis of at least one cylinder bore formed by the cylinder portion is located forward of the lower portion. In other words, the cylinder portion is tilted forward. The front portion of the cylinder portion forms part of the exhaust path, the rear portion of the cylinder portion forms part of the intake path, and the exhaust-side port of the EGR cooler is located forward of the intake-side port of the EGR cooler. Therefore, by utilizing the forward tilt of the cylinder portion, the EGR cooler can be installed so that condensed water generated in the EGR cooler flows toward the exhaust passage, thereby further reducing restrictions on the placement location of the EGR cooler. Therefore, the EGR cooler can be installed in a position where condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame by the engine and without affecting the function of the first screw fastening structure.

[0012] (4) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to any of the configurations (1) to (3) above: (i) at least a portion of the EGR cooler is integrally formed with the cylinder portion, and (ii) in the first cross section, at least a portion of the EGR cooler is disposed between the two planes that pass through the left end and the right end of the first screw fastening structure on the first cross section and are perpendicular to the central axis of the first bolt, and (iii-1) in the first cross section, an EGR cooler-related surface that is part of the left side of the engine and is formed by at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler is disposed to the right of a plane that passes through the left end of the first screw fastening structure on the first cross section and is perpendicular to the central axis of the first bolt, or (iii-2) In the first cross section, an EGR cooler-related surface, which is a part of the right side of the engine and is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler, is positioned to the left of a plane that passes through the right end of the first screw fastening structure on the first cross section and is perpendicular to the center axis of the first bolt.

[0013] According to this configuration, when the EGR cooler-related surface is a part of the left side of the engine and is composed of at least one of a surface located to the left of the EGR cooler and a surface formed by the EGR cooler, the leftmost end of the EGR cooler-related surface of the engine is located in the space surrounding the first screw fastening structure around the central axis of the first bolt in the first cross section. Also, when the EGR cooler-related surface is a part of the right side of the engine and is composed of at least one of a surface located to the right of the EGR cooler and a surface formed by the EGR cooler, the rightmost end of the EGR cooler-related surface of the engine is located in the space surrounding the first screw fastening structure around the central axis of the first bolt in the first cross section. Therefore, an increase in the length of the portion of the engine including the cylinder section and the EGR cooler in the left-right direction of the vehicle can be further suppressed, thereby further reducing restrictions on the placement position of the EGR cooler. Furthermore, with the above configuration, in the first cross section, the space surrounding the first threaded fastening structure around the central axis of the first bolt includes both the rightmost or leftmost end of the engine's EGR cooler-related surface and at least a portion of the EGR cooler. Therefore, the EGR cooler is located closer to the left or right side of the engine, or forms part of the left or right side of the engine. Therefore, airflow generated by the straddled vehicle's travel strikes the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler, thereby more efficiently dissipating a portion of the heat of the exhaust gas within the EGR cooler. This ensures the cooling performance of the EGR cooler while minimizing the need for an increased size of the EGR cooler, further easing restrictions on the placement of the EGR cooler. Therefore, the EGR cooler can be installed in a position where condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame by the engine, while further reducing restrictions on the placement location of the EGR cooler and without affecting the function of the first screw fastening structure.

[0014] (5) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to any of the configurations (1) to (4) above: two front fork sections disposed respectively on the left and right sides of the straddled vehicle, aligned along the vehicle up-down direction, and rotatably supporting at least one front wheel, when the first bolt is used to connect the frame section disposed on the left side of the straddled vehicle to the cylinder section, the EGR cooler is arranged so that, when the straddled vehicle is traveling, at least one of the airflow passing through the inside of the two front fork sections and the airflow passing through the outside of the two front fork sections hits an EGR cooler-related surface that is part of the left side of the engine and is composed of at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler, when the first bolt is used to connect the frame section disposed on the right side of the straddled vehicle to the cylinder section, The EGR cooler is arranged so that, when the straddled vehicle is traveling, at least one of the airflows passing through the inside of the two front fork sections and the airflows passing through the outside of the two front fork sections hits an EGR cooler-related surface, which is part of the right side of the engine and is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler.

[0015] This configuration achieves the following technical effects. A relatively large space is provided inside the two front fork sections because it is necessary to ensure space for the front wheel to stroke in the vehicle up-down direction relative to the body frame. Therefore, a large amount of airflow passes through the space inside the two front fork sections, and this large amount of airflow can be directed toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler. Furthermore, no other on-board components are typically located outside the two front fork sections, ensuring a large space for the airflow to pass through. Therefore, when the straddled vehicle is traveling, a large amount of airflow passes through the space outside the two front fork sections, and this large amount of airflow can be directed toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler. In this way, when the straddled vehicle is traveling, the airflow flowing around the front fork sections can be used to direct a larger amount of airflow toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler. This allows a portion of the heat of the exhaust gas inside the EGR cooler to be dissipated more efficiently. This prevents the EGR cooler from becoming too large while ensuring its cooling performance, thereby further reducing restrictions on the placement location of the EGR cooler. Therefore, the EGR cooler can be provided in a position where condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame by the engine and without affecting the function of the first screw fastening structure, while further reducing restrictions on the placement location of the EGR cooler.

[0016] (6) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to the configuration described in (5) above: a headlight unit consisting of at least one headlight, and the EGR cooler is disposed in a space above the center of rotation of the at least one front wheel in the vehicle vertical direction and below the lower end of the headlight unit so that, when the straddled vehicle is traveling, at least one of the airflows that have passed inside the two front fork units and the airflows that have passed outside the two front fork units hits an EGR cooler-related surface of the engine that is formed by at least one of (a) a surface located to the left or right of the EGR cooler and (b) a surface formed by the EGR cooler.

[0017] This configuration achieves the following technical effects. Because the front wheel is supported by the front fork at its rotation center, no space is formed between the front wheel and the front fork near the rotation center of the front wheel. However, above the rotation center, a clearance (space) is provided between the front wheel and the front fork because the front wheel rotates. This space functions as a passageway for airflow, allowing the airflow passing through the space to impinge on the EGR cooler-related surface, which is the outer surface of the engine portion including the cylinder section and the EGR cooler. Furthermore, the lower end of the headlight portion, which includes at least one headlight, is positioned below the headlight portion to ensure space for the front wheel to stroke in the vertical direction of the vehicle relative to the body frame. Therefore, a relatively large space is formed below the headlight portion, allowing a large amount of airflow to pass through this space and impinge on the EGR cooler-related surface, which is the outer surface of the engine portion including the cylinder section and the EGR cooler. In this way, when the straddled vehicle is traveling, the airflow flowing around the front fork portion in the space above the center of rotation of the front wheel and below the lower end of the headlight portion can be utilized to direct more airflow toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder portion and the EGR cooler. This allows a portion of the heat of the exhaust gas inside the EGR cooler to be more efficiently dissipated. This prevents the EGR cooler from becoming too large while maintaining its cooling performance, thereby further reducing restrictions on the EGR cooler's placement. Therefore, the EGR cooler can be positioned so that condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame due to the engine, without affecting the function of the first screw fastening structure.

[0018] (7) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to the configuration of (6) above: the EGR cooler is provided above the center of rotation of the at least one front wheel and below the lower end of the headlight in the vehicle up-down direction so that, during travel of the straddled vehicle, in a space above the center of rotation of the at least one front wheel and below the lower end of the headlight, at least one of the airflows that pass through the inside of the two front fork sections and the airflows that pass through the outside of the two front fork sections hits an EGR cooler-related surface of the engine, which is formed by at least one of (a) a surface located to the left or right of the EGR cooler and (b) a surface formed by the EGR cooler.

[0019] According to this configuration, the EGR cooler and the EGR cooler-related surface are located above the center of rotation of the front wheel and below the lower end of the headlight in the vehicle vertical direction. Therefore, when the straddled vehicle is traveling, the airflow flowing around the front fork in the space above the center of rotation of the front wheel and below the lower end of the headlight can be more reliably utilized to direct more airflow toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler. This allows a portion of the heat of the exhaust gas inside the EGR cooler to be more efficiently dissipated. This prevents the EGR cooler from becoming too large while maintaining its cooling performance, thereby further easing restrictions on the EGR cooler's placement. Therefore, the EGR cooler can be located in a position that allows condensed water generated in the EGR cooler to flow toward the exhaust passage while ensuring the rigidity of the body frame due to the engine, without affecting the function of the first screw fastening structure.

[0020] (8) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to any of the configurations (1) to (7) above. When the first bolt is used to connect the frame portion located on the left side of the straddled vehicle to the cylinder portion, at least a portion of an EGR cooler-related surface, which is a portion of the left side of the engine and is composed of at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler, is covered with a cover portion, and a gap is provided between the EGR cooler-related surface and the cover portion, through which airflow generated by the movement of the straddled vehicle passes; when the first bolt is used to connect the frame portion located on the right side of the straddled vehicle to the cylinder portion, at least a portion of an EGR cooler-related surface, which is a portion of the right side of the engine and is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler, is covered with a cover portion, and a gap is provided between the EGR cooler-related surface and the cover portion, through which airflow generated by the movement of the straddled vehicle passes.

[0021] This configuration makes it easier to ensure a gap between the EGR cooler-related surface and the cover portion. Therefore, when the straddled vehicle is traveling, a larger amount of airflow can be directed toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler. Therefore, by making better use of the airflow generated by the traveling of the straddled vehicle, a portion of the heat of the exhaust gas inside the EGR cooler can be more efficiently dissipated. This prevents the EGR cooler from becoming too large while maintaining its cooling performance, thereby further reducing restrictions on the EGR cooler's placement location. Therefore, the EGR cooler can be positioned so that condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the body frame by the engine and without affecting the function of the first screw fastening structure.

[0022] (9) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to any of the configurations (1) to (7) above: When the first bolt is used to connect the frame portion located on the left side of the straddled vehicle to the cylinder portion, an EGR cooler-related surface that is part of the left side of the engine and is composed of at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler is not covered with a cover and is exposed to the outside of the straddled vehicle; When the first bolt is used to connect the frame portion located on the right side of the straddled vehicle to the cylinder portion, an EGR cooler-related surface that is part of the right side of the engine and is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler is not covered with a cover and is exposed to the outside of the straddled vehicle.

[0023] With this configuration, because the EGR cooler-related surface is exposed to the outside, more airflow can be directed toward the EGR cooler-related surface, which is the outer surface of the portion of the engine that includes the cylinder section and the EGR cooler, when the straddled vehicle is traveling. Furthermore, as described above, the EGR cooler is located closer to the left or right side of the engine, or forms part of the left or right side of the engine. Therefore, by making better use of the airflow generated by the straddled vehicle traveling, a portion of the heat of the exhaust gas inside the EGR cooler can be more efficiently dissipated. This prevents the EGR cooler from becoming too large while maintaining its cooling performance, thereby further reducing restrictions on the EGR cooler's placement. Therefore, the EGR cooler can be located in a position that allows condensed water generated in the EGR cooler to flow toward the exhaust passage while ensuring the rigidity of the body frame due to the engine, without affecting the function of the first screw fastening structure.

[0024] (10) A straddled vehicle according to one embodiment of the present invention may have the following configuration in addition to any of the configurations (1) to (9) above: At least a portion of the EGR cooler is integrally formed with the cylinder portion so that the engine functions as a member that contributes to the rigidity of the body frame, and at least a portion of the EGR cooler is disposed between two planes in the first cross section that pass through the left and right ends of the first bolt on the first cross section, respectively, and are perpendicular to the central axis of the first bolt.

[0025] According to this configuration, the EGR cooler is installed using the cylinder section and the space surrounding the central axis of the first bolt used to connect the frame section and the cylinder section. Therefore, the EGR cooler is installed closer to the left or right side of the engine, or forms part of the left or right side of the engine. Therefore, the airflow generated by the straddled vehicle's movement hits the outer surface of the portion of the engine including the cylinder section and the EGR cooler, thereby more efficiently dissipating a portion of the heat of the exhaust gas within the EGR cooler. This prevents the EGR cooler from becoming too large while maintaining its cooling performance, thereby further easing restrictions on the EGR cooler's placement. Therefore, the EGR cooler can be installed in a position where condensed water generated in the EGR cooler can flow toward the exhaust passage while ensuring the rigidity of the vehicle body frame due to the engine, without affecting the function of the first screw fastening structure, and without affecting the placement restrictions of the EGR cooler.

[0026] In the present invention, the term "path" refers to a space through which an object such as a gas flows. This definition applies to the EGR path, the intake path, and the exhaust path in the present invention and embodiments.

[0027] In the present invention and its embodiments, the vehicle up-down direction is the direction perpendicular to a horizontal plane when the straddled vehicle is placed upright on the horizontal plane. In the present invention and its embodiments, the vehicle fore-aft direction is the direction parallel to the direction of travel of the straddled vehicle when the straddled vehicle moves straight. In the present invention and its embodiments, the vehicle left-right direction is the direction perpendicular to the vehicle up-down direction and the vehicle fore-aft direction, and is the left-right direction from the perspective of a rider riding the straddled vehicle.

[0028] In the present invention and its embodiments, a straddled vehicle refers to a vehicle on which a rider sits astride a saddle. Straddled vehicles include motorcycles, motor tricycles, all-terrain vehicles (ATVs), snowmobiles, and personal watercraft. Straddled vehicles include scooters, motorized bicycles, and mopeds. Motor tricycles have one or two front wheels. A straddled vehicle in the present invention and its embodiments may have at least one front wheel. A straddled vehicle in the present invention and its embodiments may be a lean vehicle in which the body frame leans to the right relative to the vertical direction of the vehicle when turning right and to the left relative to the vertical direction of the vehicle when turning left. In the present invention and its embodiments, the drive source of a straddled vehicle may be an engine alone, or both an engine and an electric motor. The electric motor as a drive source does not include a starter motor that is used only to start the engine.

[0029] In the present invention and embodiments, the left part of the straddled vehicle is the part to the left of the center of the straddled vehicle in the left-right direction of the vehicle, and the right part of the straddled vehicle is the part to the right of the center of the straddled vehicle in the left-right direction of the vehicle.

[0030] In the present invention and embodiments, the straddled vehicle has an engine. In the present invention and embodiments, the engine may be a four-stroke engine. The engine may be a multi-cylinder engine having multiple combustion chambers. The engine may be a parallel multi-cylinder engine having multiple combustion chambers aligned in the left-right direction of the vehicle. The engine may be a V-engine configured in a V-shape when viewed in the left-right direction of the vehicle. The engine may be a single-cylinder engine having one combustion chamber.

[0031] In the present invention and embodiments, the number of at least one cylinder hole formed by the cylinder portion may be one or more. The combustion chamber is formed by the cylinder hole, the piston disposed in the cylinder hole, and the cylinder head portion. When the cylinder portion forms multiple cylinder holes, the multiple cylinder holes formed by the cylinder portion may be arranged side by side on a straight line parallel to the left-right direction of the vehicle.

[0032] In the present invention and its embodiments, the central axis of the cylinder bore is not a line segment that exists only in the region where the cylinder bore exists, but a straight line that extends infinitely. The upper part of the central axis of the cylinder bore may be located further forward in the longitudinal direction of the vehicle than the lower part of the central axis of the cylinder bore. If the engine is a V-type engine having a front cylinder section that defines at least one cylinder bore and a rear cylinder section that is disposed rearward of the front cylinder section, the upper part of the central axis of the at least one cylinder bore defined by the front cylinder section is located further forward in the longitudinal direction of the vehicle than the lower part. The rear cylinder section does not have to be included in the cylinder section of the present invention.

[0033] In the present invention and its embodiments, a cylinder portion consisting of a cylinder head portion and a cylinder body portion refers to a cylinder portion consisting only of the cylinder head portion and the cylinder body portion. The cylinder head portion is configured to be separable from the cylinder body portion. The cylinder head portion may be configured with multiple separable parts, or may be configured with a single, inseparable part. For example, the cylinder head portion may be configured with multiple separable parts including a head cover. The cylinder body portion is connected to a crankcase portion of the engine. The cylinder body portion forms at least one cylinder hole. The crankcase portion houses a crankshaft. The crankcase portion has at least one of a portion protruding leftward from the left surface of the cylinder portion and a portion protruding rightward from the right surface of the cylinder portion. The crankcase portion corresponds to the gearbox housing of Patent Document 1. The cylinder body portion may be configured to be separable from the crankcase portion. Alternatively, the cylinder body portion and at least a portion of the crankcase portion may form a single part. In this case, the boundary between the cylinder body portion and the crankcase portion is located on a plane that passes through the end of at least one cylinder hole formed by the cylinder body portion and is perpendicular to at least one cylinder axis.

[0034] In the present invention and embodiments, the engine functioning as a member that contributes to the rigidity of the body frame means that the engine increases the rigidity of the portion of the body frame that includes the two frame portions compared to when the two frame portions and the cylinder portion are not connected. In other words, at least the cylinder portion of the engine functions as a member that contributes to the rigidity of the body frame.

[0035] In the present invention and embodiments, the two frame portions disposed on the left and right sides of the straddled vehicle may be disposed along the longitudinal direction of the vehicle, although "disposed along the longitudinal direction of the vehicle" does not necessarily mean "disposed parallel to the longitudinal direction of the vehicle."

[0036] In the present invention and its embodiments, connecting two frame portions and a cylinder portion without a vibration-absorbing member means connecting the two frame portions and the cylinder portion without a member for absorbing engine vibrations. In a typical automobile, the engine is supported on the vehicle frame via a vibration-absorbing member made of rubber or the like, called an engine mount. In the present invention and its embodiments, the multiple bolts used to connect the two frame portions and the cylinder portion refer to multiple bolts that directly connect the two frame portions and the cylinder portion, or multiple bolts that connect the two frame portions and the cylinder portion via multiple brackets. The number of bolts used to connect each frame portion to the cylinder portion may be one or more. When the two frame portions and the cylinder portion are directly connected, the central axes of the multiple bolts may be parallel or approximately parallel to each other. When the two frame portions and the cylinder portion are connected via multiple brackets, the central axes of the multiple bolts may be parallel or approximately parallel to each other. When two frame sections and a cylinder section are connected via multiple brackets, the central axes of some of the bolts may be parallel or approximately parallel to each other and perpendicular or approximately perpendicular to the central axes of the remaining bolts.

[0037] In the present invention and embodiments, the central axis of the first bolt along the vehicle left-right direction may be parallel or approximately parallel to the vehicle left-right direction. In the present invention and embodiments, the central axis of the first bolt is not a line segment that exists only in the area where the first bolt is present, but is a straight line that extends infinitely. When two frame portions and a cylinder portion are connected via multiple brackets, the first bolt may be a bolt that connects one of the two frame portions to the bracket. In the present invention and embodiments, the first bolt may be located on the left or right portion of the straddled vehicle.

[0038] In the present invention and embodiments, the first screw hole into which the first bolt is inserted may be formed in a bracket, a cylinder portion, or a nut for connecting one of two frame portions to the cylinder portion. When the two frame portions and the cylinder portion are directly connected, the first screw hole may be formed in the cylinder portion. When the two frame portions and the cylinder portion are connected via multiple brackets, the first screw hole may be formed in the cylinder portion, the bracket, or the nut. The first screw hole has a thread groove that threadably engages with the first bolt. The first screw hole may be a through hole or a non-through hole. The first screw hole refers to the entire hole into which the first bolt is inserted. In other words, the first screw hole may include a portion of the hole where the first bolt is not present.

[0039] In the present invention and embodiments, a first screw fastening structure consisting of a first bolt and a first screw hole refers to a first screw fastening structure consisting only of a first bolt and a first screw hole. In the present invention and embodiments, the first screw fastening structure may be disposed on the left or right part of the straddled vehicle. In the present invention and embodiments, the left and right ends of the first screw fastening structure on the first cross section are the leftmost and rightmost ends of the first screw fastening structure on the first cross section. The left and right ends of the first screw fastening structure on the first cross section are not necessarily the leftmost and rightmost ends of the first screw fastening structure in three-dimensional space. The left and right ends of the first screw fastening structure on the first cross section may be a combination of the left or right end of the first bolt on the first cross section and the left or right end of the first screw hole on the first cross section. When the first screw hole is formed in a nut, the left and right ends of the first screw fastening structure on the first cross section may be the left and right ends of the first bolt on the first cross section.

[0040] In the present invention and embodiments, the intake path is directly connected to at least one combustion chamber of the engine. Air supplied to at least one combustion chamber of the engine flows through the intake path. A portion of the intake path is formed inside the cylinder portion. A portion of the intake path is disposed outside the engine and is formed by an intake pipe or the like. A rear portion of the cylinder portion may form part of the intake path. The rear portion of the cylinder portion is a portion of the cylinder portion that is located rearward of a plane that passes through the central axis of the cylinder bore and is parallel to the left-right direction of the vehicle. The intake path has at least one downstream end in the air flow direction. The number of at least one downstream ends of the intake path may be the same as or greater than the number of combustion chambers.

[0041] In the present invention and embodiments, the exhaust path is directly connected to at least one combustion chamber of the engine. Exhaust gas discharged from at least one combustion chamber of the engine flows through the exhaust path. A portion of the exhaust path is formed inside the cylinder portion. A portion of the exhaust path is disposed outside the engine and is formed by an exhaust pipe or the like. A front portion of the cylinder portion may form part of the exhaust path. The front portion of the cylinder portion is a portion of the cylinder portion that is located forward of a plane that passes through the central axis of the cylinder bore and is parallel to the left-right direction of the vehicle. The exhaust path has at least one upstream end in the flow direction of the exhaust gas. The number of at least one upstream ends of the exhaust path may be the same as or greater than the number of combustion chambers.

[0042] In the present invention and embodiments, the EGR path is directly connected to the intake path and the exhaust path. The EGR path may be connected to the exhaust path and the intake path outside the engine. The EGR path may be connected to the exhaust path and the intake path inside the engine (cylinder portion). The EGR path may be connected to the exhaust path inside the engine (cylinder portion) and connected to the intake path outside the engine. The EGR path may be connected to the exhaust path outside the engine and connected to the intake path inside the engine (cylinder portion). In the present invention and embodiments, the EGR path may be connected to the exhaust path at one or more points. If the engine has multiple combustion chambers, the EGR path may be connected to the exhaust path such that a portion of exhaust gas discharged from each of the multiple combustion chambers flows into the EGR path. If the engine has multiple combustion chambers, the EGR path may be connected to the exhaust path such that only a portion of exhaust gas discharged from at least one of the multiple combustion chambers flows into the EGR path. In the present invention and embodiments, the number of points at which the EGR path is connected to the intake path may be one or more. In the present invention and embodiments, the EGR path may be provided with an EGR valve that adjusts the flow rate of exhaust gas flowing through the EGR path. The EGR valve may be disposed in the EGR path between the intake path and the EGR cooler.

[0043] In the present invention and embodiments, the EGR cooler is configured to cool exhaust gases flowing into the EGR cooler from the exhaust-side port. The EGR cooler may be configured to cool the exhaust gases using a coolant (e.g., water) that cools the cylinder section. In this case, the EGR cooler includes at least a wall located between the EGR path and a coolant path through which the coolant flows. The engine may have a coolant path dedicated to the EGR cooler, or a portion of the coolant path for cooling the cylinder section may also serve as a coolant path for the EGR cooler. Regardless of the engine cooling method, the EGR cooler may be configured to cool the exhaust gases using airflow generated by the movement of the straddled vehicle. In this case, the EGR cooler includes fins that increase the contact area with the airflow to improve heat exchange efficiency.

[0044] In the present invention and embodiments, "the EGR cooler is configured so that condensed water generated by cooling the exhaust gas is discharged from the exhaust-side port and flows toward the exhaust path" means that the EGR cooler and the EGR path are configured so that condensed water generated in the EGR cooler by cooling the exhaust gas flows toward the exhaust-side port of the EGR cooler and is discharged from the exhaust-side port, and the condensed water discharged from the exhaust-side port flows through the EGR path toward the exhaust path. Condensed water generated by cooling the exhaust gas by the EGR cooler is discharged from the exhaust-side port and flows toward the exhaust path by gravity. In the present invention and embodiments, "condensed water generated by cooling the exhaust gas is discharged from the exhaust-side port and flows toward the exhaust path" includes condensed water generated in the EGR cooler by cooling the exhaust gas by the EGR cooler being discharged from the exhaust-side port and flowing into the exhaust path. The condensed water discharged from the exhaust-side port may evaporate before reaching the exhaust path.

[0045] In the present invention and embodiments, the EGR path inside the EGR cooler may be located to the right or left of the center of the straddled vehicle in the left-right direction of the vehicle. In this specification, the term "EGR path inside the EGR cooler" refers to a portion of the EGR path that is located inside the EGR cooler. In the present invention and embodiments, the EGR cooler may be located to the right or left of the center of the straddled vehicle in the left-right direction of the vehicle. When viewed in a direction parallel to the central axis of at least one cylinder hole formed by the cylinder portion, the EGR path inside the EGR cooler may be located to the right of the central axis of the rightmost cylinder hole of the at least one cylinder hole formed by the cylinder portion, or to the left of the central axis of the leftmost cylinder hole of the at least one cylinder hole formed by the cylinder portion. The EGR cooler may be disposed to the right of the rightmost cylinder hole of the at least one cylinder hole formed by the cylinder portion, or to the left of the leftmost cylinder hole of the at least one cylinder hole formed by the cylinder portion, as viewed in a direction parallel to the central axis of the at least one cylinder hole formed by the cylinder portion. In the present invention and embodiments, the flow direction of exhaust gas in at least a portion of the EGR path inside the EGR cooler may be a direction perpendicular to the vehicle transverse direction. Note that the direction perpendicular to the vehicle transverse direction here is not limited to a direction parallel to the direction perpendicular to the vehicle transverse direction, but also includes a direction inclined within a range of ±45° in the vehicle transverse direction with respect to the direction perpendicular to the vehicle transverse direction. The EGR path may be configured to branch into multiple paths near the exhaust-side port inside the EGR cooler and then converge again near the intake-side port inside the EGR cooler. The EGR path may not branch or converge inside the EGR cooler.

[0046] In the present invention and embodiments, "at least a portion of the EGR cooler is integrally formed with the cylinder section" means that at least a portion of the EGR cooler is integrally formed with a portion of the cylinder section that has a function as a cylinder section other than the cooling function of the EGR cooler. The portion that functions as a cylinder section may be, for example, a portion that forms a cylinder bore. In the present invention and embodiments, when a portion of the EGR cooler is separate from the cylinder section, the portion of the EGR cooler that is separate from the cylinder section may be disposed at a position inside the cylinder section and away from the outer surface of the cylinder section, or may be attached to the outer surface of the cylinder section. In the present invention and embodiments, when the entire EGR cooler is integrally formed with the cylinder section, the EGR cooler may be provided at a position inside the cylinder section and away from the outer surface of the cylinder section, or may form the outer surface of the cylinder section. In the present invention and embodiments, at least a portion of a wall that forms an EGR path inside the EGR cooler may be integrally formed with the cylinder section. In the present invention and embodiments, the wall that forms the EGR path inside the EGR cooler may be formed of aluminum or an aluminum alloy.

[0047] Here, when the first bolt is used to connect a frame portion located on the left side of the straddled vehicle to a cylinder portion, a surface that is a part of the left side of the engine and is composed of at least one of a surface located to the left of the EGR cooler and a surface formed by the EGR cooler is referred to as the EGR cooler-related surface. Also, when the first bolt is used to connect a frame portion located on the right side of the straddled vehicle to a cylinder portion, a surface that is a part of the right side of the engine and is composed of at least one of a surface located to the right of the EGR cooler and a surface formed by the EGR cooler is referred to as the EGR cooler-related surface. The EGR cooler-related surface appears as a line in the above-mentioned first cross section. In the present invention and embodiments, the EGR cooler-related surface may be located in the first cross section between two planes that pass through the left and right ends of the first screw fastening structure on the first cross section, respectively, and are perpendicular to the central axis of the first bolt. The EGR cooler-related surface may be located between two planes in the first cross section that pass through a left end and a right end of the first bolt, respectively, on the first cross section and are perpendicular to the central axis of the first bolt. The EGR cooler-related surface may be located in the first cross section to the left of a line that passes through the left end of the first screw fastening structure and is perpendicular to the central axis of the first bolt, or to the right of a line that passes through the right end of the first screw fastening structure on the first cross section and is perpendicular to the central axis of the first bolt. In either the case where the entire EGR cooler is integrally formed with the cylinder section or the case where a portion of the EGR cooler is integrally formed with the cylinder section, the EGR cooler-related surface may be a surface located to the left or right of the EGR cooler, a surface formed by the EGR cooler, or a surface constituted by both a surface located to the left or right of the EGR cooler and a surface formed by the EGR cooler.

[0048] In the present invention and embodiments, the EGR path inside the EGR cooler may be disposed between two planes that pass through the left and right ends of the first screw fastening structure on the first cross section and are perpendicular to the central axis of the first bolt. The EGR path inside the EGR cooler may be disposed between two planes that pass through the left and right ends of the first bolt on the first cross section and are perpendicular to the central axis of the first bolt. Here, when the first bolt is used to connect a frame portion disposed on the left side of the straddled vehicle to a cylinder portion, a surface that is part of the left side of the engine and is located to the left of the EGR path inside the EGR cooler is referred to as the EGR cooler path-related surface. Furthermore, when the first bolt is used to connect a frame portion disposed on the right side of the straddled vehicle to a cylinder portion, a surface that is part of the right side of the engine and is located to the right of the EGR path inside the EGR cooler is referred to as the EGR cooler path-related surface. In the present invention and embodiments, the EGR cooler path-related surface may be disposed between two planes in the first cross section that pass through the left and right ends of the first screw fastening structure on the first cross section and are perpendicular to the central axis of the first bolt. The EGR cooler path-related surface may be disposed between two planes in the first cross section that pass through the left and right ends of the first bolt on the first cross section and are perpendicular to the central axis of the first bolt. The EGR cooler path-related surface may be disposed to the left of a plane that passes through the left end of the first screw fastening structure on the first cross section and is perpendicular to the central axis of the first bolt, or to the right of a plane that passes through the right end of the first screw fastening structure on the first cross section and is perpendicular to the central axis of the first bolt. The EGR cooler path-related surface is a part of the EGR cooler path-related surface. Therefore, when an airflow generated by the running of the straddled vehicle hits the EGR cooler path-related surface, a portion of the airflow hits the EGR cooler path-related surface.In the present invention and embodiments, the EGR path inside the EGR cooler may be located above the center of rotation of at least one front wheel in the vehicle up-down direction and below the lower end of the headlight so that, during travel of the straddled vehicle, at least one of the airflows passing through the inside of the two front fork sections and the airflows passing through the outside of the two front fork sections strikes the EGR cooler path-related surface in a space above the center of rotation of at least one front wheel in the vehicle up-down direction and below the lower end of the headlight section. In the present invention and embodiments, at least a portion of the EGR cooler path-related surface may be covered with a cover. In this case, a gap may be provided between the EGR cooler path-related surface and the cover, through which airflow generated by travel of the straddled vehicle can pass. In the present invention and embodiments, the EGR cooler path-related surface may be exposed to the outside of the straddled vehicle without being covered with the cover.

[0049] In the present invention and its embodiments, the front fork portion is made up of one or more front forks. The front fork is a rod-shaped member that extends in the vertical direction of the vehicle, and the front fork is not bifurcated (forked) by itself. The front fork portion is also not bifurcated (forked). If the straddled vehicle has one front wheel, the front fork portion may be made up of one front fork. If the straddled vehicle has two front wheels, the front fork portion may be made up of multiple front forks. Specifically, a pair of right front forks supporting the right front wheel and a pair of left front forks supporting the left front wheel may each constitute one front fork portion.

[0050] In the present invention and its embodiments, the straddled vehicle may have a headlight unit consisting of at least one headlight. The headlight unit may be composed of a single headlight located at the center of the straddled vehicle in the left-right direction, or may be composed of two headlights located on each of the left and right sides of the straddled vehicle. The center of the headlight unit in the left-right direction may be the center of the straddled vehicle in the left-right direction. The headlight unit may be a part that is visible when viewed from the front of the straddled vehicle. The headlight may be located in a hole formed in the front cover. In this case, when viewed from the front of the straddled vehicle, a space is provided below the lower end of the front cover located below the headlight unit to allow the front wheel to stroke in the vertical direction of the vehicle relative to the body frame. In this specification, the space formed below the lower end of the front cover located below the headlight unit may sometimes be referred to as the space below the headlight unit.

[0051] In the present invention and its embodiments, the cover portion forms part of the exterior of the straddled vehicle. The cover portion may be an independent member, a part of an independent member, or may be composed of multiple independent members. The cover portion may be a tank shroud that is provided so as to appear integrated with the tank alone in appearance. The cover portion may also be at least a part of a cover known as a front cowl or a side cowl. The cover portion may also be a protector provided to protect at least the EGR cooler.

[0052] In the present invention and embodiments, the engine cooling system may be air-cooled or liquid-cooled using a coolant other than lubricating oil, and lubricating oil cooling may be combined with an air-cooled or liquid-cooled engine.

[0053] In the present invention and embodiments, the engine may be provided with a fuel supply device that supplies fuel to a combustion chamber of the engine. The fuel supply device may be arranged to supply fuel directly to the combustion chamber of the engine. The fuel supply device may be arranged to supply fuel to an intake path.

[0054] In the present invention and its embodiments, the straddled vehicle may or may not have a forced induction device that pressurizes the air supplied to the combustion chamber of the engine. The forced induction device may be a turbocharger, a mechanical supercharger, or an electric supercharger. The turbocharger may be an electrically assisted turbocharger that can pressurize air using exhaust gas pressure and an electric motor, or a turbocharger that pressurizes air using exhaust gas pressure alone.

[0055] In the present invention and embodiments, the straddled vehicle may have a catalyst in the exhaust path that purifies exhaust gas. For example, the catalyst may be disposed in the exhaust path downstream in the flow direction of the exhaust gas from a position where the EGR path is connected.

[0056] In this specification, "A is to the left of B in the left-right direction" refers to the following state: The entirety of A is to the left of a plane that passes through the leftmost end of B and is perpendicular to the left-right direction. The rightmost end of A may or may not be on a plane that passes through the leftmost end of B and is perpendicular to the left-right direction. A and B may or may not be lined up on a straight line parallel to the left-right direction. The above definition also applies, with appropriate terminology replaced, to the expression "A is to the right of B in the left-right direction." The above definition also applies, with appropriate terminology replaced, to the expression "A is above or below B in the up-down direction." The above definition also applies, with appropriate terminology replaced, to the expression "A is forward or rearward of B in the front-to-back direction."

[0057] In this specification, unless otherwise specified, "A is to the left of B in the left-right direction" includes both the case where A is to the left of only a portion of B in the left-right direction and the case where A is to the left of all of B in the left-right direction. "A is to the left of B in the left-right direction" refers to the following state: when viewed left-right, all of A overlaps with at least a portion of B, and the right end of all of A faces the left end of at least a portion of B in the left-right direction. Note that the above definition also applies, with appropriate terminology replaced, to the expression "A is to the right of B in the left-right direction." Furthermore, the above definition also applies, with appropriate terminology replaced, to the expression "A is above or below B in the up-down direction." Furthermore, the above definition also applies, with appropriate terminology replaced, to the expression "A is in front of or behind B in the front-to-back direction."

[0058] In the present invention and embodiments, the terms including, comprising, having, and their derivatives are used to encompass additional items in addition to the listed items and their equivalents. In the present invention and embodiments, the terms mounted, connected, coupled, and supported are used broadly to specifically include not only direct mounting, connection, coupling, and support, but also indirect mounting, connection, coupling, and support. Furthermore, connected and coupled are not limited to physical or mechanical connections / couplings; they also include direct or indirect electrical connections / couplings.

[0059] Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification and claims have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Terms, such as those defined in commonly used dictionaries, should be interpreted to have a meaning consistent with the meaning in the context of the relevant technology and this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0060] It should be noted that in this specification, the term "may" is non-exclusive. "may" means "may, but is not limited to." In this specification, "may" implicitly includes the possibility that "may not."

[0061] Before describing embodiments of the present invention in detail, it is to be understood that the invention is not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present invention may be practiced in embodiments other than those described below. The present invention may also be practiced in embodiments with various variations on the embodiments described below.

[0062] According to the present invention, it is possible to provide a straddled vehicle in which the EGR cooler, whose placement position is restricted in order to flow condensed water generated in the EGR cooler toward the exhaust passage, is provided in a configuration different from that of Patent Document 1, and the engine functions as a member that contributes to the rigidity of the vehicle frame.

[0063] Fig. 1 is a diagram for explaining the configuration of a straddled vehicle according to a first embodiment of the present invention. Fig. 2 is a diagram for explaining the configuration of a straddled vehicle according to a second embodiment of the present invention. Fig. 3 is a diagram for explaining the configuration of a straddled vehicle according to a third embodiment of the present invention. Fig. 4 is a diagram for explaining the configuration of a straddled vehicle according to a fourth embodiment of the present invention. Fig. 5 is a diagram for explaining the configuration of a straddled vehicle according to a fifth embodiment of the present invention. Fig. 6 is a diagram for explaining the configuration of a straddled vehicle according to a sixth embodiment of the present invention.

[0064] Arrows F, Re, L, R, U, and D shown in each drawing represent the forward, backward, left, right, upward, and downward directions of the vehicle, respectively.

[0065] [First embodiment] A straddled vehicle 1 according to a first embodiment of the present invention will be described below with reference to Figures 1(a) to 1(p). Straddled vehicles 1 according to second to sixth embodiments, which will be described later, all have the same configuration as the first embodiment. Figures 1(c) to 1(p) show several specific examples of the first embodiment, but the specific examples of the first embodiment are not limited to these.

[0066] As shown in Figure 1(a), the straddled vehicle 1 comprises a body frame 30 and an engine 2. The engine 2 includes a cylinder section 3 consisting of a cylinder head section 4 and a cylinder body section 5. As shown in Figure 1(b), the body frame 30 has two frame sections 31 arranged on the left and right sides of the straddled vehicle 1, respectively.

[0067] The straddled vehicle 1 is equipped with an EGR cooler 20. FIGS. 1(c) to 1(j) show eight examples of the layout of the EGR cooler 20 included in the straddled vehicle 1 of the first embodiment. FIGS. 1(c) to 1(j) are partially enlarged views of FIG. 1(a). The EGR cooler 20 is provided in an EGR path 13 that recirculates a portion of exhaust gas generated in the engine 2 from the exhaust path 11 to the intake path 12. The EGR cooler 20 has an exhaust-side port 21 through which the exhaust gas flows in and an intake-side port 22 through which the exhaust gas flows out. The EGR cooler 51 is configured so that the lower end of the exhaust-side port 21 is located lower than the intake-side port 22 in the vehicle vertical direction. The EGR cooler 20 cools the exhaust gas that flows in through the exhaust-side port 21, and condensed water generated by cooling the exhaust gas is discharged from the exhaust-side port 21 and flows toward the exhaust path 11.

[0068] The straddled vehicle 1 of the first embodiment has the following configuration so that the engine 2 functions as a member that contributes to the rigidity of the vehicle body frame 30. At least a portion of the EGR cooler 20 is formed integrally with the cylinder section 3. The two frame sections 31 and the cylinder section 3 are connected using a plurality of bolts 33 without any vibration absorbing member interposed therebetween. In a first cross section X1 (X1a to X1p) that passes through a central axis Cb of a first bolt 33a, which is one of the plurality of bolts 33, in the left-right direction of the vehicle and is parallel to the central axis Cb, at least a portion of the EGR cooler 20 is disposed between two planes SF1 and SF2 that pass through left and right ends, respectively, on the first cross section X1 of a first screw fastening structure 35 that is made up of the first bolt 33a and a first screw hole 34 into which the first bolt 33a is inserted and are perpendicular to the central axis Cb of the first bolt 33a. The plane SF1 passes through the left end of the first screw fastening structure 35 on the first cross section X1, and the plane SF2 passes through the right end of the first screw fastening structure 35 on the first cross section X1.

[0069] Figures 1(c) to 1(f) show an example where at least a portion of the EGR cooler 20 is formed integrally with the cylinder head portion 4, and Figures 1(g) to 1(j) show an example where at least a portion of the EGR cooler 20 is formed integrally with the cylinder body portion 5. Figures 1(c) to 1(j) show an example where the first bolt 33a is used to connect the frame portion 31 located on the left side of the straddled vehicle 1 to the cylinder portion 3. The first bolt 33a may also be the bolt 33 used to connect the frame portion 31 located on the right side of the straddled vehicle 1 to the cylinder portion 3.

[0070] Figures 1(c) to 1(j) show examples in which the straddled vehicle 1 has two bolts 33 corresponding to the first bolt 33a. The first cross sections X1 corresponding to the two first bolts 33a in Figure 1(c) are designated X1a and X1b. The first cross sections X1 corresponding to a total of 14 first bolts 33a in Figures 1(d) to 1(j) are designated X1c to X1p. The first cross section X1 is a general term for the first cross sections X1a to X1p. In Figures 1(c) to 1(j), the first bolt 33a is either a bolt 33 that directly connects the frame portion 31 and the cylinder portion 3, or a bolt 33 used to connect the frame portion 31 and the cylinder portion 3 via a bracket 32.

[0071] 1(k) to 1(p) show examples of the first cross sections X1a to X1p in FIGS. 1(c) to 1(j). In FIGS. 1(k) to 1(p), the EGR cooler 20 is hatched with dots, and the EGR path 13 inside the EGR cooler 20 is not shown.

[0072] At least a portion of the EGR cooler 20 may be integrally formed with at least a portion of the cylinder portion 3 that is made of aluminum or an aluminum alloy.

[0073] [Second embodiment] A straddled vehicle 1 according to a second embodiment of the present invention will now be described with reference to Figures 2(a) and 2(b). Figures 2(a) and 2(b) show specific examples of the second embodiment, but the specific examples of the second embodiment are not limited to these. Figure 2(a) shows an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder head 4, and Figure 2(b) shows an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder body 5.

[0074] In the second embodiment, the engine 2 is disposed such that an upper portion of the central axis Cc of at least one cylinder bore 6 formed by the cylinder section 3 is located forward in the vehicle longitudinal direction relative to a lower portion. The front portion of the cylinder section 3 forms a part of the exhaust path 11, and the rear portion of the cylinder section 3 forms a part of the intake path 12. In the vehicle longitudinal direction, the exhaust-side opening 21 of the EGR cooler 20 is located forward of the intake-side opening 22.

[0075] [Third Embodiment] A straddled vehicle 1 according to a third embodiment of the present invention will now be described with reference to Figures 3(a) to 3(e). The straddled vehicle 1 according to the third embodiment may have the same configuration as the second embodiment. Figures 3(a) to 3(e) show several specific examples of the third embodiment, but the specific examples of the third embodiment are not limited to these. Figure 3(a) shows an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder head 4, and Figure 3(b) shows an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder body 5. Figure 3(c) shows an example of a first cross section X1 in Figures 3(a) and 3(b). Similarly, Figures 3(d) and 3(e) show examples of the first cross section X1 in Figures 3(a) and 3(b), respectively.

[0076] Here, the EGR cooler-related surface 23 is defined as follows. When the first bolt 33a is used to connect the frame portion 31 located on the left side of the straddled vehicle 1 to the cylinder portion 3, the EGR cooler-related surface 23 is a part of the left side of the engine 2 and is a surface formed by at least one of a surface located to the left of the EGR cooler 20 and a surface formed by the EGR cooler 20. When the first bolt 33a is used to connect the frame portion 31 located on the right side of the straddled vehicle 1 to the cylinder portion 3, the EGR cooler-related surface 23 is a part of the right side of the engine 2 and is a surface formed by at least one of a surface located to the right of the EGR cooler 20 and a surface formed by the EGR cooler 20. This definition of the EGR cooler-related surface 23 will also be used in the description of the fourth and fifth embodiments described later. Figures 3(a) to 3(e) show examples in which the EGR cooler-related surface 23 is a part of the left side of the engine 2. 3(a) and 3(b), the EGR cooler-related surface 23 is hatched with dots, while in Figures 3(c) to 3(e), the EGR cooler-related surface 23 is indicated by a thick line.

[0077] In the third embodiment, the EGR cooler-related surface 23 defined above has the following characteristics. When the EGR cooler-related surface 23 is a part of the left surface of the engine 2, in the first cross section X1, the EGR cooler-related surface 23 is positioned to the right of a plane SF1 that passes through the left end of the first screw fastening structure 35 in the first cross section X1 and is perpendicular to the central axis Cb of the first bolt 33 a. When the EGR cooler-related surface 23 is a part of the right surface of the engine 2, in the first cross section X1, the EGR cooler-related surface 23 is positioned to the left of a plane SF2 that passes through the right end of the first screw fastening structure 35 in the first cross section X1 and is perpendicular to the central axis Cb of the first bolt 33 a.

[0078] In Figures 3(c) to (e), the EGR cooler 20 is configured to cool the exhaust gas by using the coolant that cools the cylinder portion 3. In Figures 3(c) and (e), the EGR cooler 20 has a coolant path 24 dedicated to the EGR cooler. In Figure 3(d), the EGR cooler 20 is provided adjacent to the coolant path 7 for cooling the cylinder portion 3, and is configured to cool the exhaust gas by using the coolant that flows through this coolant path 7. In Figure 3(c), a portion 20a of the EGR cooler 20 is separate from the cylinder portion 3, and the remaining portion of the EGR cooler 20 is formed integrally with the cylinder portion 3. In Figures 3(d) and (e), the entire EGR cooler 20 is formed integrally with the cylinder portion 3.

[0079] [Fourth Embodiment] A straddled vehicle 1 according to a fourth embodiment of the present invention will be described below with reference to Figures 4(a) to 4(d). The straddled vehicle 1 according to the fourth embodiment may have the same configuration as at least one of the second and third embodiments. Figures 4(a) to 4(d) show several specific examples of the fourth embodiment, but the specific examples of the fourth embodiment are not limited to these. Figure 4(a) shows an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder head 4, and Figure 4(b) shows an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder body 5. Figures 4(c) and 4(b) are cross-sectional views taken along lines A-A in Figure 4(a) and B-B in Figure 4(b), respectively, and show two examples of the layout of the EGR cooler 20. The EGR cooler-related surface 23 is defined in the same manner as the EGR cooler-related surface 23 in the third embodiment. 4A to 4D show an example in which the EGR cooler-related surface 23 is a part of the left surface of the engine 2. FIG.

[0080] The straddled vehicle 1 of the fourth embodiment is provided with two front fork portions 40 that rotatably support at least one front wheel 50. Figures 4(a) to 4(d) show an example in which there is one front wheel 50. The two front fork portions 40 are disposed on the left and right sides of the straddled vehicle 1, respectively, and are aligned in the vertical direction of the vehicle.

[0081] In the fourth embodiment, the EGR cooler 20 is provided so that, when the straddled vehicle 1 is traveling, at least one of the airflow passing through the inside of the two front fork portions 40 and the airflow passing through the outside of the two front fork portions 40 hits the EGR cooler-related surface 23. In Figures 4(a) to 4(d), the airflow is indicated by thick arrows.

[0082] The straddled vehicle 1 of the fourth embodiment may have a headlight unit 60 consisting of at least one headlight. A plane that passes through the center of rotation of at least one front wheel 50 and is perpendicular to the vehicle vertical direction is defined as plane F1. A plane that passes through the lower end of the headlight unit 60 and is perpendicular to the vehicle vertical direction is defined as plane F2. In the fourth embodiment, the EGR cooler 20 may be provided in a space above plane F1 and below plane F2 in the vehicle vertical direction so that at least one of the airflow that passes inside the two front fork units 40 and the airflow that passes outside the two front fork units 40 hits the EGR-cooler-related surface 23 when the straddled vehicle 1 is traveling. In the fourth embodiment, the EGR cooler 20 may be provided above plane F1 and below plane F2 in the vehicle vertical direction.

[0083] Fifth Embodiment A straddled vehicle 1 according to a fifth embodiment of the present invention will be described below with reference to FIGS. 5( a) to 5(d). The straddled vehicle 1 according to the fifth embodiment may have the same configuration as at least one of the second to fourth embodiments. FIGS. 5( a) to 5(d) illustrate several specific examples of the fifth embodiment, but the specific examples of the fifth embodiment are not limited to these. FIG. 5(a) illustrates an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder head 4, and FIG. 5(b) illustrates an example in which at least a portion of the EGR cooler 20 is integrally formed with the cylinder body 5. FIGS. 5(c) and 5(d) are cross-sectional views taken along lines CC in FIG. 5(a) and DD in FIG. 5(b), respectively, and illustrate two examples of the layout of the EGR cooler 20. The EGR cooler-related surface 23 is defined in a manner similar to the definition of the EGR cooler-related surface 23 in the third embodiment. 5A to 5D show an example in which the EGR cooler-related surface 23 is a part of the left surface of the engine 2. FIG.

[0084] In the fifth embodiment, at least a portion of the EGR cooler-related surface 23 is covered with a cover portion 70. Furthermore, a gap is provided between the EGR cooler-related surface 23 and the cover portion 70, through which airflow generated by the movement of the straddled vehicle 1 passes. In Figures 5(a) to 5(d), the airflow is indicated by thick arrows.

[0085] Sixth Embodiment A straddled vehicle 1 according to a sixth embodiment of the present invention will be described below with reference to FIGS. 6( a) to 6(e). The straddled vehicle 1 according to the sixth embodiment may have the same configuration as at least one of the second to fifth embodiments. FIGS. 6(a) to 6(e) show several examples of the first cross section X1 according to the sixth embodiment. FIGS. 6(a) to 6(e) show examples in which the first bolt 33a is used to connect the frame portion 31 located on the left side of the straddled vehicle 1 to the cylinder portion 3. The representation of the EGR cooler 20 in FIGS. 6(a) to 6(e) is the same as the representation of the EGR cooler 20 in FIGS. 1(k) to 1(p). The EGR cooler 20 according to the sixth embodiment is not limited to the examples shown in FIGS. 6(a) to 6(e).

[0086] In the sixth embodiment, in the first cross section X1, at least a portion of the EGR cooler 20 is disposed between two planes SF3 and SF4 that pass through the left and right ends of the first bolt 33a on the first cross section X1, respectively, and are perpendicular to the central axis Cb of the first bolt 33a.

[0087] In the first to fourth and sixth embodiments, the EGR cooler-related surface 23 may not be covered by the cover portion 70 and may be exposed to the outside of the straddled vehicle 1, contrary to the fifth embodiment.

[0088] 1: straddled vehicle, 2: engine, 3: cylinder portion, 4: cylinder head portion, 5: cylinder body portion, 6: cylinder hole, 11: exhaust path, 12: intake path, 13: EGR path, 21: exhaust side port, 22: intake side port, 23: EGR cooler-related surface, 30: vehicle body frame, 31: frame portion, 33: bolt, 33a: first bolt, 34: first screw hole, 35: first screw fastening structure, 40: front fork portion, 50: front wheel, 60: headlight portion, 70: cover portion, Cb: central axis of first bolt, Cc: central axis of cylinder hole, SF1, SF2, SF3, SF4: plane, X1, X1a to X1p: first cross section

Claims

1. A straddled vehicle equipped with an EGR cooler that is provided in an EGR path that recirculates a portion of exhaust gas generated in an engine from the exhaust path to the intake path, has an exhaust side port through which the exhaust gas flows in and an intake side port through which the exhaust gas flows out, and is configured so that a lower end of the exhaust side port is located lower than the intake side port in the vertical direction of the vehicle, cools the exhaust gas, and condensed water generated by the cooling of the exhaust gas is discharged from the exhaust side port and flows toward the exhaust path, wherein: (i) at least a portion of the EGR cooler is formed integrally with a cylinder portion that is included in the engine and is composed of a cylinder head portion and a cylinder body portion, and (ii) A straddled vehicle characterized in that, in a first cross section passing through a central axis along the left-right direction of the vehicle and parallel to a central axis of a first bolt, which is one of a plurality of bolts used to connect the cylinder portion and two frame portions respectively located on the left and right sides of the straddled vehicle and included in the body frame without using a vibration absorbing member, at least a portion of the EGR cooler is positioned between two planes that pass through the left and right ends, respectively, on the first cross section of a first screw fastening structure consisting of the first bolt and a first screw hole into which the first bolt is inserted, and are perpendicular to the central axis of the first bolt.

2. A straddled vehicle as described in claim 1, characterized in that at least a portion of the EGR cooler is integrally formed with at least a portion of the cylinder portion, which is made of aluminum or an aluminum alloy, so that the engine functions as a member that contributes to the rigidity of the body frame, and in the first cross-section, at least a portion of the EGR cooler is positioned between the two planes that pass through the left and right ends, respectively, on the first cross-section of the first screw fastening structure and are perpendicular to the central axis of the first bolt.

3. A straddled vehicle as described in claim 1 or 2, characterized in that an upper part of the central axis of at least one cylinder hole formed by the cylinder portion is located forward of the lower part in the vehicle fore-and-aft direction, a front part of the cylinder portion forms part of the exhaust path, and a rear part of the cylinder portion forms part of the intake path, at least a part of the EGR cooler is formed integrally with the cylinder portion so that the engine functions as a member contributing to the rigidity of the body frame, and the exhaust side port of the EGR cooler is located forward of the intake side port in the vehicle fore-and-aft direction, and in the first cross section, at least a part of the EGR cooler is positioned between the two planes that pass through the left and right ends, respectively, on the first cross section of the first screw fastening structure and are perpendicular to the central axis of the first bolt.

4. In order for the engine to function as a member that contributes to the rigidity of the vehicle body frame, (i) at least a portion of the EGR cooler is integrally formed with the cylinder portion, and (ii) in the first cross section, at least a portion of the EGR cooler is disposed between the two planes that pass through the left end and the right end of the first screw fastening structure on the first cross section and are perpendicular to the central axis of the first bolt, and (iii-1) in the first cross section, a part of the left side of the engine, an EGR cooler-related surface constituted by at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler, is disposed to the right of a plane that passes through the left end of the first screw fastening structure on the first cross section and is perpendicular to the central axis of the first bolt, or (iii-2) A straddled vehicle as described in any one of claims 1 to 3, characterized in that in the first cross section, an EGR cooler-related surface, which is a part of the right side of the engine and is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler, is positioned to the left of a plane that passes through the right end of the first screw fastening structure on the first cross section and is perpendicular to the center axis of the first bolt.

5. The straddled vehicle comprises two front fork parts respectively disposed on the left and right parts of the straddled vehicle, aligned in the vertical direction of the vehicle, and rotatably supporting at least one front wheel; when the first bolt is used to connect the frame part disposed on the left part of the straddled vehicle to the cylinder part, the EGR cooler is arranged so that, when the straddled vehicle is traveling, at least one of the airflows passing through the inside of the two front fork parts and the airflows passing through the outside of the two front fork parts contact an EGR cooler-related surface which is a part of the left side of the engine and is composed of at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler; when the first bolt is used to connect the frame part disposed on the right part of the straddled vehicle to the cylinder part, A straddled vehicle as described in any one of claims 1 to 4, characterized in that when the straddled vehicle is traveling, at least one of the air flows passing through the inside of the two front fork parts and the air flows passing through the outside of the two front fork parts hits an EGR cooler-related surface which is a part of the right side of the engine and is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler.

6. A straddled vehicle as described in claim 5, characterized in that it has a headlight section consisting of at least one headlight, and the EGR cooler is arranged so that, when the straddled vehicle is traveling, within a space above the center of rotation of the at least one front wheel in the vertical direction of the vehicle and below the lower end of the headlight section, at least one of the air flows that pass through the inside of the two front fork sections and the air flows that pass through the outside of the two front fork sections hits the EGR cooler-related surface of the engine, which is composed of at least one of (a) a surface located to the left or right of the EGR cooler and (b) a surface formed by the EGR cooler.

7. A straddled vehicle as described in claim 6, characterized in that the EGR cooler is arranged above the center of rotation of the at least one front wheel and below the lower end of the headlight in the vertical direction of the vehicle so that, during travel of the straddled vehicle, in a space above the center of rotation of the at least one front wheel and below the lower end of the headlight, at least one of the air flows that pass through the inside of the two front fork parts and the air flows that pass through the outside of the two front fork parts hits the EGR cooler-related surface of the engine, which is composed of at least one of (a) a surface located to the left or right of the EGR cooler and (b) a surface formed by the EGR cooler.

8. A straddled vehicle as claimed in any one of claims 1 to 7, characterized in that when the first bolt is used to connect the frame part located on the left part of the straddled vehicle to the cylinder part, at least a part of an EGR cooler-related surface which is a part of the left side of the engine and which is constituted by at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler is covered with a cover part; and when the first bolt is used to connect the frame part located on the right part of the straddled vehicle to the cylinder part, at least a part of an EGR cooler-related surface which is a part of the right side of the engine and which is constituted by at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler is covered with a cover part; and a gap is provided between the EGR cooler-related surface and the cover part, through which airflow generated by the movement of the straddled vehicle can pass.

9. A straddled vehicle as claimed in any one of claims 1 to 7, characterized in that when the first bolt is used to connect the frame part located on the left part of the straddled vehicle to the cylinder part, an EGR cooler-related surface which is a part of the left side of the engine and which is composed of at least one of (a) a surface located to the left of the EGR cooler and (b) a surface formed by the EGR cooler is not covered by a cover part and is exposed to the outside of the straddled vehicle; and when the first bolt is used to connect the frame part located on the right part of the straddled vehicle to the cylinder part, an EGR cooler-related surface which is a part of the right side of the engine and which is composed of at least one of (a) a surface located to the right of the EGR cooler and (b) a surface formed by the EGR cooler is not covered by a cover part and is exposed to the outside of the straddled vehicle.

10. A straddled vehicle as described in any one of claims 1 to 9, characterized in that at least a portion of the EGR cooler is integrally formed with the cylinder section so that the engine functions as a member that contributes to the rigidity of the body frame, and in the first cross section, at least a portion of the EGR cooler is positioned between two planes that pass through the left and right ends of the first bolt on the first cross section, respectively, and are perpendicular to the central axis of the first bolt.

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