Leaning vehicle

Abstract

An entire EGR path (50) including an EGR cooler path (52) of this leaning vehicle (1) is disposed above the uppermost end of a cylinder body portion (13) disposed such that an upper portion of the cylinder axis (Cy) is positioned further forward than a lower portion. A thermostat (41) provided in the EGR cooler path and an engine coolant path (40) is disposed on the inside of a bifurcated main frame part (3) when viewed in the axial direction of a head pipe (4) and above the lowermost end of the cylinder part and below the uppermost end of the cylinder part such that condensed water generated in the EGR cooler path returns to an exhaust path, and such that any two side surfaces among three side surfaces excluding a right side surface (11r) or a left side surface (11l) close to a camshaft drive mechanism (17) of a cylinder part (11) arranged such that the lowermost end of a rear surface (11b) forming a part of an intake path (20) is positioned above the lowermost end of a front surface (11f) forming a part of the exhaust path (30) are the closest side surfaces.

Description

Lean vehicle

[0001] The present invention relates to a lean vehicle having an EGR path.

[0002] Conventionally, an exhaust gas recirculation (EGR) path is known that recirculates a portion of exhaust gas discharged from an engine combustion chamber back into an intake path. For example, Patent Document 1 discloses a motorcycle having an EGR path. In Patent Document 1, a portion of the EGR path is formed in a body frame to efficiently supply cooled exhaust gas to the intake path, and the body frame dissipates heat from the exhaust gas. Patent Document 1 describes that by using the body frame to cool the exhaust gas, an EGR cooler provided in the EGR path can be downsized or eliminated.

[0003] Patent No. 5283898

[0004] Lean vehicles such as motorcycles are required to have an EGR path equipped with an EGR cooler while suppressing an increase in size in the left-right direction of the lean vehicle.

[0005] An object of the present invention is to provide a lean vehicle that has an EGR path provided with an EGR cooler, while preventing the lean vehicle from becoming larger in the left-right direction.

[0006] (1) A lean vehicle according to one embodiment of the present invention has the following configuration: (A) (A1) a body frame including a head pipe extending in the vertical direction of the vehicle and having a main frame portion bifurcated from the head pipe as viewed in the axial direction of the head pipe, (A2) which leans to the right of the vehicle when turning right and to the left of the vehicle when turning left, (B) the engine including (B1) a cylinder portion including a cylinder body portion forming at least one cylinder hole and a cylinder head portion connected to the cylinder body portion and constituting an end of the engine in the direction of at least one cylinder axis that is the central axis of the at least one cylinder hole, and which forms at least one combustion chamber, (B2) a crankshaft that rotates about an axis extending in the left-right direction of the vehicle, and (B3) a camshaft drive mechanism that is disposed inside the engine so as to be located to the right or left of the at least one cylinder hole formed in the cylinder body portion in the left-right direction of the vehicle, and that transmits a driving force of the crankshaft to at least one camshaft disposed inside the cylinder head portion, and (C) a vehicle body frame including a main frame portion bifurcated from the head pipe when turning right and left, (B2) a body frame including a main frame portion bifurcated from the head pipe when turning right and left, (B2) a body frame including a main frame portion bifurcated from the head pipe when turning left, (B2) a body frame including a main frame portion bifurcated from the head pipe when turning right, (B2) a body frame including a main frame portion bifurcated from the head pipe when turning left, (B2) a body frame including a main frame portion bifurcated from the head pipe when turning right, and (B2) a body frame including a main frame portion bifurcated from the head pipe when turning left, and (B2) a body frame including a main frame portion bifurcated from the head pipe when turning left, and (B2) a body frame including a main frame portion bifurcated from the head pipe when turning right, and (B2) a body frame including a main frame portion bifu a lean-fuel vehicle including an intake path connected to a combustion chamber and an exhaust path connected to the at least one combustion chamber, and an EGR path connecting the intake path and the exhaust path to recirculate a portion of exhaust gas passing through the exhaust path to the intake path, the lean-fuel vehicle further including an engine coolant path provided with a thermostat and through which a coolant other than lubricating oil flows, the thermostat being disposed inside the main frame portion having a bifurcated shape as viewed in the axial direction of the head pipe, and the EGR path being an EGR path disposed inside the main frame portion having a bifurcated shape as viewed in the axial direction of the head pipe. an EGR cooler path formed within a cooler and having a lowermost end located above a lowermost end of at least one EGR path exhaust side end connected to the exhaust path in the EGR path, the entire EGR path including the EGR cooler path being disposed above a first plane that passes through the uppermost end of the cylinder body portion disposed so that an upper portion of the at least one cylinder axis is located forward of a lower portion in the vehicle longitudinal direction and is perpendicular to the at least one cylinder axis, and the EGR cooler path and the thermostat areThe cylinder section is arranged so that (i) condensed water generated in at least the EGR cooler path returns to the exhaust path, and (ii) an upper part of the at least one cylinder axis is located forward of a lower part and the lowermost end of a rear side surface forming a part of the intake path is located higher than the lowermost end of a front side surface forming a part of the exhaust path, and any two of three side surfaces excluding the right side surface or the left side surface close to the camshaft drive mechanism are the side closest to the EGR cooler path and the side closest to the thermostat, respectively, above a second plane passing through the lowermost end of the cylinder section and perpendicular to the at least one cylinder axis, below a third plane passing through the uppermost end of the cylinder section and perpendicular to the at least one cylinder axis, and inside the bifurcated main frame section when viewed in the axial direction of the head pipe.

[0007] According to this configuration, the entire EGR path, including the EGR cooler path, is positioned above a first plane that passes through the uppermost end of the cylinder body portion, which is positioned so that the upper portion of at least one cylinder axis is located forward of the lower portion in the vehicle longitudinal direction, and is perpendicular to at least one cylinder axis. Therefore, space can be secured around the cylinder body portion for arranging piping (e.g., coolant piping or an exhaust pipe) and electrical components other than the EGR path while minimizing interference with the EGR path. Furthermore, the EGR path can be positioned around the cylinder head portion while minimizing interference with piping and electrical components arranged around the cylinder body portion. Furthermore, the EGR cooler path and the thermostat are arranged above a second plane that passes through the bottom end of the cylinder portion and is perpendicular to at least one cylinder axis, below a third plane that passes through the top end of the cylinder portion and is perpendicular to at least one cylinder axis, and inside the bifurcated main frame portion when viewed in the axial direction of the head pipe, so that (i) condensed water generated in at least the EGR cooler path returns to the exhaust path, and (ii) the cylinder portion is arranged so that the upper part of at least one cylinder axis is located forward of the lower part and the lowermost end of the rear side surface that forms part of the intake path is located higher than the lowermost end of the front side surface that forms part of the exhaust path, and any two of the three side surfaces, excluding the right side surface or the left side surface that is close to the camshaft drive mechanism, are the side closest to the EGR cooler path and the side closest to the thermostat, respectively. Therefore, by utilizing the fact that the cylinder section is arranged so that the upper part of at least one cylinder axis is located forward of the lower part and the lowest end of the rear surface that forms a part of the intake path is located higher than the lowest end of the front surface that forms a part of the exhaust path, the EGR cooler path can be arranged so that condensed water generated in the EGR cooler path returns to the exhaust path, thereby simplifying the EGR cooler path.Furthermore, the EGR cooler path and the thermostat are disposed above a second plane passing through the bottom end of the cylinder section and perpendicular to at least one cylinder axis, below a third plane passing through the top end of the cylinder section and perpendicular to at least one cylinder axis, and inside the bifurcated main frame section as viewed in the axial direction of the head pipe, so that two of the three side surfaces of the cylinder section, excluding the right side surface or the left side surface near the camshaft drive mechanism, are the side surface closest to the EGR cooler path and the side surface closest to the thermostat, respectively. This allows the EGR cooler path and the thermostat to be disposed around the cylinder head section while suppressing interference between the EGR cooler path and the thermostat. Furthermore, the main frame section can be prevented from becoming larger in the left-right direction than if one of the EGR cooler path and the thermostat were disposed near the right side surface or the left side surface near the camshaft drive mechanism of the cylinder section and inside the bifurcated main frame section as viewed in the axial direction of the head pipe. As a result, the lean vehicle has an EGR path equipped with an EGR cooler, while preventing the lean vehicle from becoming larger in the left-right direction.

[0008] (2) In addition to the configuration of (1) above, a lean-fuel vehicle according to one embodiment of the present invention may have the following configuration: the entire EGR path including the EGR cooler path is disposed above the first plane that passes through an uppermost end of the cylinder body portion that is disposed so that an upper portion of the at least one cylinder axis is located forward of a lower portion of the at least one cylinder axis and is perpendicular to the at least one cylinder axis, and is disposed below the third plane that passes through the uppermost end of the cylinder portion and is perpendicular to the at least one cylinder axis.

[0009] With this configuration, the entire EGR path, including the EGR cooler path, is positioned below the third plane that passes through the uppermost end of the cylinder section and is perpendicular to at least one cylinder axis, so the EGR path can be positioned while minimizing interference with piping (e.g., intake piping) and electrical equipment that are positioned above the upper surface of the cylinder section. This makes it easier to prevent the lean vehicle from becoming larger in the lateral direction above the upper surface of the cylinder section.

[0010] (3) In addition to the configuration of (2) above, a lean vehicle according to one embodiment of the present invention may have the following configuration: The EGR cooler path is arranged to face the first cylinder head side surface of the cylinder head portion in a direction perpendicular to the at least one cylinder axis, or is arranged at a position inside the cylinder head portion close to the first cylinder head side surface, so that a first cylinder head side surface, which is one of three side surfaces excluding the right side surface or the left side surface close to the camshaft drive mechanism, of the cylinder head portion included in the cylinder portion arranged so that an upper portion of the at least one cylinder axis is located forward of a lower portion of the at least one cylinder axis, is the side surface closest to the EGR cooler path.

[0011] According to this configuration, when the EGR cooler path is arranged to face the first cylinder head side surface of the cylinder head portion in a direction perpendicular to at least one cylinder axis so that the first cylinder head side surface of the cylinder head portion is the side surface closest to the EGR cooler path, the design flexibility of the EGR path is high. Therefore, even if an EGR path equipped with an EGR cooler is arranged, it is easy to suppress an increase in the left-right dimension of a lean-engine vehicle. Furthermore, when the EGR cooler path is arranged in a position close to the first cylinder head side surface inside the cylinder head portion so that the first cylinder head side surface of the cylinder head portion is the side surface closest to the EGR cooler path, it is easy to shorten the path length of the EGR path. Therefore, even if an EGR path equipped with an EGR cooler is arranged, it is easy to suppress an increase in the left-right dimension of a lean-engine vehicle.

[0012] 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, intake path, exhaust path, and engine coolant path in the present invention and the embodiments.

[0013] In the present invention and the embodiments, the vehicle up-down direction is the direction perpendicular to a horizontal plane when the lean vehicle is placed upright on the horizontal plane. The vehicle left-right direction is the left-right direction for a rider riding on the lean vehicle. The vehicle front-rear direction is the direction perpendicular to the vehicle up-down direction and the vehicle left-right direction, and is the front-rear direction for a rider riding on the lean vehicle. The vehicle forward direction is the direction in which the lean vehicle travels straight.

[0014] In the present invention and the embodiments, the body frame tilting to the right of the vehicle means that the body frame tilts to the right of the vehicle relative to the vertical direction of the vehicle. In other words, it means that the upper part of the body frame tilts so that it is positioned further to the right of the vehicle than the lower part. The definition of the body frame tilting to the left of the vehicle is the same as above.

[0015] In the present invention and the embodiments, the main frame portion is a part of the body frame. The main frame portion does not have to be a single independent part, as long as it has a head pipe and a bifurcated portion from the head pipe. A steering shaft is disposed inside the head pipe of the main frame portion. In the present invention and the embodiments, a head pipe aligned along the vertical direction of the vehicle means a head pipe positioned so that the angle of the axial direction of the head pipe with respect to the vertical direction of the vehicle is greater than −45° and less than +45°.

[0016] In the present invention and the embodiments, the rotation axis of the crankshaft is aligned with the left-right direction of the vehicle. The rotation axis of the crankshaft may be parallel to the left-right direction of the vehicle when the lean vehicle is in an upright position.

[0017] In the present invention and the embodiments, the number of at least one combustion chamber formed by the cylinder section may be one or more. When the cylinder section forms multiple combustion chambers, the multiple combustion chambers formed by the cylinder section are arranged side by side in the left-right direction of the vehicle. In the present invention and the embodiments, the engine may be a single-cylinder engine or a multi-cylinder engine. The engine may be an in-line multi-cylinder engine having multiple combustion chambers arranged side by side in the left-right direction of the vehicle. The engine may be a V-type engine having a cylinder section having at least one combustion chamber and a rear cylinder section arranged rearward of the cylinder section. The rear cylinder section is not included in the cylinder section of the present invention.

[0018] In the present invention and its embodiments, the number of at least one cylinder hole formed by the cylinder body portion is the same as the number of at least one combustion chamber formed by the cylinder portion. The combustion chamber is formed by the cylinder hole, the piston disposed in the cylinder hole, and the cylinder head portion. When the cylinder body portion forms multiple cylinder holes, the multiple cylinder axes, which are the central axes of the multiple cylinder holes, are parallel to each other. In the present invention and its embodiments, the cylinder axis is not a line segment that exists only in the region where the cylinder hole exists, but a straight line that extends infinitely.

[0019] In the present invention and in the embodiments, the cylinder portion is configured so that the cylinder head portion and the cylinder body portion can be separated. The cylinder portion may include a gasket disposed between the cylinder head portion and the cylinder body portion. At least one cylinder axial end of the cylinder portion is at least one cylinder axial end of the cylinder head portion and at least one cylinder axial end of the cylinder body portion. In the present invention and in the embodiments, the cylinder portion has four side surfaces. The four side surfaces of the cylinder portion do not include at least one end surface in the cylinder axial direction. The four side surfaces of the cylinder portion intersect with at least one cylinder axial direction. The four side surfaces of the cylinder portion are a side surface (right side surface) seen when the cylinder portion is viewed to the left of the vehicle, a side surface (left side surface) seen when the cylinder portion is viewed to the right of the vehicle, a side surface (front side surface) seen when the cylinder portion is viewed in a direction perpendicular to the direction perpendicular to at least one cylinder axis and along the vehicle rearward direction, and a side surface (rear side surface) seen when the cylinder portion is viewed in a direction perpendicular to the direction perpendicular to at least one cylinder axis and along the vehicle frontward direction.

[0020] In the present invention and its embodiments, the cylinder head portion may be composed of multiple separable parts, or may be composed of a single, inseparable part. For example, the cylinder head portion may be composed of multiple parts including a head cover. The cylinder head portion has four side surfaces. The definition of the four side surfaces of the cylinder head portion is the same as the definition of the four side surfaces of the cylinder portion described above. In the present invention and its embodiments, the cylinder body portion may be composed of multiple separable parts, may be composed of a single, inseparable part, or may be composed of a part of a single, inseparable part. For example, 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 in the cylinder body portion and is perpendicular to at least one cylinder axis. The cylinder body portion has four side surfaces. The definition of the four side surfaces of the cylinder body portion is the same as the definition of the four side surfaces of the cylinder portion described above.

[0021] In the present invention and its embodiments, "the upper part of at least one cylinder axis is located forward of the lower part" means that, when at least one cylinder axis is divided into an upper part and a lower part by a plane perpendicular to the vehicle vertical direction, the upper part of at least one cylinder axis is located forward of the lower part of at least one cylinder axis in the vehicle longitudinal direction. In the present invention and its embodiments, "arranging a cylinder section so that the lowermost end of its rear side surface, which forms part of the intake path, is located higher than the lowermost end of its front side surface, which forms part of the exhaust path" means that the cylinder section has a rear side surface, which forms part of the intake path, and a front side surface, which forms part of the exhaust path, and the lowermost end of the rear side surface of the cylinder section is located higher in the vehicle vertical direction than the lowermost end of its front side surface. In the present invention and its embodiments, "arranging an object above a plane perpendicular to at least one cylinder axis" means that the object is located in the upper space of two spaces separated by a plane perpendicular to at least one cylinder axis. The definition of "arranging below a plane perpendicular to at least one cylinder axis" is the same as above.

[0022] In the present invention and embodiments, the camshaft drive mechanism may be composed of, for example, a crankshaft, multiple sprockets or multiple pulleys provided on at least one camshaft, and a chain or belt wound around the multiple sprockets or multiple pulleys. The camshaft is provided to drive an intake valve that opens and closes the intake path and an exhaust valve that opens and closes the exhaust path. The camshaft drive mechanism is disposed inside the engine so as to be located to the right or left of at least one cylinder hole formed in the cylinder body in the vehicle transverse direction. A portion of the camshaft drive mechanism is disposed inside the cylinder portion so as to follow the right or left side surface of the cylinder portion. A portion of the camshaft drive mechanism is disposed inside the cylinder body so as to follow the right or left side surface of the cylinder body. The camshaft drive mechanism is closer to either the right or left side surface of the cylinder portion. When the camshaft drive mechanism is located to the left of at least one cylinder hole formed in the cylinder body in the vehicle transverse direction, the camshaft drive mechanism is closer to the left side of the right or left side surface of the cylinder portion. When the camshaft drive mechanism is located to the right of at least one cylinder hole formed in the cylinder body portion in the left-right direction of the vehicle, the camshaft drive mechanism is closer to the right side of the right and left side surfaces of the cylinder portion.

[0023] In the present invention and the embodiments, the engine coolant path is provided to at least cool the engine. The coolant flowing through the engine coolant path is not particularly limited as long as it is a liquid that is not lubricating oil and has a cooling function. The coolant may be, for example, water. In addition to a thermostat, the engine coolant path may be provided with a coolant pump and a radiator.

[0024] A portion of the engine coolant path is formed within the thermostat. The thermostat includes a valve and controls the flow of coolant depending on the coolant temperature. The thermostat adjusts the flow rate of coolant sent to the radiator depending on the coolant temperature, for example. The thermostat is, for example, a three-way valve. The thermostat may also be a two-way or four-way valve. The thermostat may be directly attached to the cylinder section or may be connected to the cylinder section via a coolant pipe.

[0025] In the present invention and embodiments, the intake path is directly connected to at least one combustion chamber. Air supplied to at least one combustion chamber flows through the intake path. A portion of the intake path is formed inside the cylinder head. A portion of the intake path is arranged outside the engine and is formed by an intake pipe or the like. 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. One or two downstream ends of the intake path may be provided for one combustion chamber. When the number of downstream ends of the intake path is multiple, the portion of the intake path including the multiple downstream ends may have a branch shape that divides the air flow.

[0026] In the present invention and embodiments, the exhaust path is directly connected to at least one combustion chamber. Exhaust gas discharged from at least one combustion chamber flows through the exhaust path. A portion of the exhaust path is formed inside the cylinder head. A portion of the exhaust path is disposed outside the engine and is formed by an exhaust pipe or the like. 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. One or two upstream ends of the exhaust path may be provided for one combustion chamber. When the number of upstream ends of the exhaust path is multiple, the portion of the exhaust path including the multiple upstream ends may be formed to collect exhaust gas flowing in from the multiple upstream ends.

[0027] In the present invention and embodiments, the EGR path is directly connected to the intake path and the exhaust path. In the present invention and embodiments, the EGR path has at least one EGR path exhaust end connected to the exhaust path. The number of the at least one EGR path exhaust end of the EGR path may be one or more. When the number of at least one upstream end of the exhaust path is one, the number of the at least one EGR path exhaust end of the EGR path is one. When the number of at least one upstream end of the exhaust path is multiple, the number of the at least one EGR path exhaust end of the EGR path may be one or more. When the number of at least one exhaust path is multiple and the number of at least one EGR path exhaust end of the EGR path is multiple, the multiple EGR path exhaust ends of the EGR path are located upstream of a position where exhaust gases flowing in from the multiple upstream ends of the exhaust path gather. When the number of upstream ends of at least one exhaust path is multiple and the number of exhaust-side ends of at least one EGR path is single, the exhaust-side end of one EGR path may be located downstream of or upstream from a position where exhaust gases flowing in from the multiple upstream ends of the exhaust path gather. When the cylinder unit has multiple combustion chambers, the EGR path may be connected to the exhaust path so that a portion of exhaust gas discharged from each of the multiple combustion chambers flows into the EGR path. When the cylinder unit has multiple combustion chambers, the EGR path may be connected to the exhaust path so 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 EGR path has at least one EGR path intake-side end connected to the intake path. The number of EGR path intake-side ends of the at least one EGR path may be one or multiple. In the present invention and the 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, for example, between at least one EGR path intake end of the EGR path and the EGR cooler path.

[0028] In the present invention and in the embodiments, the EGR cooler is configured to cool the exhaust gas flowing through the EGR path. The EGR cooler may be configured to cool the exhaust gas using the coolant flowing through the engine coolant path. The EGR cooler may be configured to cool the exhaust gas using the airflow generated by running a lean vehicle. In the present invention and in the embodiments, the EGR cooler path is the portion of the EGR path formed within the EGR cooler.

[0029] In the present invention and the embodiments, the phrase "the lowermost end of the EGR cooler passage is located above the lowermost end of at least one EGR passage exhaust-side end of the EGR passage" does not relate to whether the EGR cooler passage is aligned with the at least one EGR passage exhaust-side end in the vertical direction of the vehicle. When there are multiple at least one EGR passage exhaust-side ends, the lowermost end of the EGR cooler passage is located above the lowermost end of the EGR passage exhaust-side end that is located lowest among the multiple EGR passage exhaust-side ends of the EGR passage. The lowermost end of the EGR cooler passage may be located above or below the uppermost end of the at least one EGR passage exhaust-side end of the EGR passage.

[0030] In the present invention and embodiments, the EGR cooler passage is arranged so that at least condensed water generated in the EGR cooler passage returns to the exhaust passage. This sentence means that the EGR cooler passage is arranged so that condensed water generated in the EGR cooler passage returns to the exhaust passage. Furthermore, this sentence means that the EGR cooler passage may be arranged so that condensed water generated in a portion of the EGR passage other than the EGR cooler passage returns to the exhaust passage. "Condensed water generated in the EGR cooler passage returning to the exhaust passage" means that condensed water generated in the EGR cooler passage returns to the exhaust passage by gravity. Condensed water is generated when water vapor in the exhaust gas is cooled and condensed.

[0031] In the present invention and embodiments, the EGR cooler path and the thermostat are arranged so that two of the three sides of the cylinder section, excluding the right or left side close to the camshaft drive mechanism, are the sides closest to the EGR cooler path and the sides closest to the thermostat, respectively. Here, "the three sides of the cylinder section, excluding the right or left side close to the camshaft drive mechanism" refers to the three sides of the four sides of the cylinder section, excluding the right or left side close to the camshaft drive mechanism. Also, here, "the side closest to the EGR cooler path" refers to the side of the four sides of the cylinder section that is closest to the EGR cooler path. Similarly, here, "the side closest to the thermostat" refers to the side of the four sides of the cylinder section that is closest to the thermostat. When the EGR cooler passage is arranged so that a first side surface of the cylinder section is the side closest to the EGR cooler passage, the EGR cooler passage is arranged so as to face the first side surface of the cylinder section in a direction perpendicular to at least one cylinder axis, or is arranged at a position inside the cylinder section close to the first side surface. "Arrangement of the EGR cooler passage so as to face the first side surface of the cylinder section in a direction perpendicular to at least one cylinder axis" includes not only cases where the EGR cooler is located away from the first side surface of the cylinder section, but also cases where the EGR cooler is in contact with the first side surface of the cylinder section. The phrase "arrangement of the EGR cooler passage so as to face the first side surface of the cylinder section in a direction perpendicular to at least one cylinder axis" does not matter, regardless of the flow direction of exhaust gas in the EGR cooler passage. When the thermostat is arranged so that the second side surface of the four side surfaces of the cylinder portion is the side closest to the thermostat, the thermostat is arranged so as to face the second side surface of the cylinder portion, or is arranged at a position inside the cylinder portion close to the second side surface. "Arrangement of the thermostat so as to face the second side surface of the cylinder portion" includes not only cases where the thermostat is arranged away from the second side surface of the cylinder portion, but also cases where the thermostat is in contact with the second side surface of the cylinder portion.

[0032] In the present invention and the embodiments, the lean vehicle may be, for example, a motorcycle or a three-wheeled motor vehicle having one or two front wheels. In the present invention and the embodiments, the lean vehicle may have, as a drive source, at least one of an electric motor that generates a drive force transmitted to a crankshaft and an electric motor that generates a drive force that is transmitted to drive wheels without passing through a crankshaft. The electric motor as a drive source does not include a starter motor that is used only to start the engine.

[0033] In the present invention and embodiments, the engine may be provided with a fuel supply device that supplies fuel. The fuel supply device may be arranged to supply fuel directly to the combustion chamber. In this case, at least a portion of the fuel supply device may be arranged in a hole formed in a rear side surface of the cylinder section, or in a hole formed in at least one end surface of the cylinder section in the cylinder axis direction. The fuel supply device may also be arranged to supply fuel to the intake path.

[0034] In the present invention and embodiments, the lean-fuel vehicle may or may not have a forced induction device that pressurizes air to supply the compressed air to the combustion chamber. 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. For example, the turbine wheel of the turbocharger may be disposed downstream in the exhaust gas flow direction from a position where the exhaust gas recirculation (EGR) path is connected to the exhaust side end of at least one EGR path. The turbine wheel of the turbocharger may be disposed upstream in the exhaust gas flow direction from a position where the exhaust gas recirculation (EGR) path is connected to the exhaust side end of at least one EGR path.

[0035] In the present invention and the embodiments, a lean 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 exhaust gas flow direction from a position where the exhaust side end of at least one EGR path of the EGR path is connected.

[0036] In the present invention and the 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 the 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.

[0037] 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.

[0038] 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."

[0039] Before describing the embodiments of the present invention in detail, it should be understood that the present invention is not limited to the details of construction and 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 incorporating various modifications of the embodiments described below. Furthermore, the present invention may be practiced by appropriately combining the embodiments and modifications described below.

[0040] According to the lean vehicle of the present invention, it is possible to prevent the lean vehicle from becoming large in size in the left-right direction while having an EGR path provided with an EGR cooler.

[0041] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments and is not to be limited to the disclosed exemplary embodiments.

[0042] Arrows F, Re, U, D, L, and R shown in Figures 1 to 3 represent the forward, rearward, upward, downward, leftward, and rightward directions of the vehicle, respectively.

[0043] <First embodiment> A lean-fuel vehicle 1 according to a first embodiment of the present invention will be described below with reference to Fig. 1. Fig. 1 shows several examples of the layout of an EGR cooler path 52 and a thermostat 41 (described later) that the lean-fuel vehicle 1 according to the first embodiment has. However, the lean-fuel vehicle 1 according to the first embodiment is not limited to the example shown in Fig. 1.

[0044] The lean vehicle 1 has a body frame 2. The body frame 2 leans to the right of the vehicle when the lean vehicle 1 turns right, and leans to the left of the vehicle when the lean vehicle 1 turns left. The body frame 2 has a main frame portion 3 including a head pipe 4 that extends along the vertical direction of the vehicle. When viewed in the axial direction of the head pipe 4, the main frame portion 3 has a bifurcated shape that branches off from the head pipe 4. The axial direction of the head pipe 4 is the direction of the central axis P of the head pipe 4. FIG. 1 includes a view seen in a direction parallel to the central axis P of the head pipe 4 and along the downward direction of the vehicle. The central axis P of the head pipe 4 is located in the center of the lean vehicle 1 in the left-right direction of the vehicle.

[0045] The lean-fuel vehicle 1 has an engine 10. The engine 10 has a cylinder section 11 that defines at least one combustion chamber 12. The cylinder section 11 includes a cylinder body section 13 and a cylinder head section 14. The cylinder body section 13 defines at least one cylinder bore 15. The cylinder head section 14 is connected to the cylinder body section 13 and defines an end of the engine 10 in the direction of at least one cylinder axis Cy, which is the central axis of the at least one cylinder bore 15. The engine 10 also has a crankshaft 16 that rotates about an axis Cl that extends along the left-right direction of the vehicle. The engine 10 also has a camshaft drive mechanism 17. The camshaft drive mechanism 17 is configured to transmit the driving force of the crankshaft 16 to at least one camshaft 18 disposed inside the cylinder head section 14. While FIG. 1 illustrates the camshaft drive mechanism 17 having one at least one camshaft 18, the camshaft drive mechanism 17 may have multiple camshafts 18. The camshaft drive mechanism 17 is disposed inside the engine 10 so as to be located to the right or left in the vehicle left-right direction of at least one cylinder hole 15 formed in the cylinder body portion 13. In the example of Fig. 1, the camshaft drive mechanism 17 is located to the right of the at least one cylinder hole 15, but this is not limiting.

[0046] The cylinder section 11 is arranged such that an upper portion of at least one cylinder axis Cy is located forward of a lower portion in the vehicle longitudinal direction. At least one combustion chamber 12 is connected to an intake path 20 and an exhaust path 30. The cylinder section 11 is arranged such that a lowermost end of a rear side surface 11b, which forms a part of the intake path 20, is located above a lowermost end of a front side surface 11f, which forms a part of the exhaust path 30.

[0047] The lean vehicle 1 has an engine coolant path 40. A portion of the engine coolant path 40 is formed inside the engine 10. Note that FIG. 1 shows only a portion of the engine coolant path 40 that is formed inside the cylinder body portion 13, and most of the engine coolant path 40 is not shown. A coolant other than lubricating oil flows through the engine coolant path 40. A thermostat 41 is provided in the engine coolant path 40. The thermostat 41 is disposed inside the bifurcated main frame portion 3 when viewed in the axial direction of the head pipe 4 (the direction of the axis P). FIG. 1 shows thermostats 41a to 41f, which are six examples of the placement of one thermostat 41 provided in the engine coolant path 40.

[0048] The lean-fuel vehicle 1 has an EGR path 50. The EGR path 50 connects the intake path 20 and the exhaust path 30 and is configured to recirculate a portion of exhaust gas passing through the exhaust path 30 back to the intake path 20. The EGR path 50 includes an EGR cooler path 52 formed within an EGR cooler 51. The EGR path 50 may be provided with an EGR valve (not shown) that adjusts the flow rate of exhaust gas flowing through the EGR path 50. The EGR cooler 51 is disposed inside the bifurcated main frame portion 3 as viewed in the axial direction (direction of the axis P) of the head pipe 4. The lowermost end of the EGR cooler path 52 is located above the lowermost end of at least one EGR path exhaust-side end 50a of the EGR path 50 that is connected to the exhaust path 30. Although FIG. 1 illustrates the EGR path 50 having one at least EGR path exhaust-side end 50a, the EGR path 50 may have multiple EGR path exhaust-side ends 50a.

[0049] The entire EGR path 50, including the EGR cooler path 52, is positioned above a first plane S1 that passes through the uppermost end of the cylinder body portion 13, which is positioned so that the upper part of at least one cylinder axis Cy is located forward in the vehicle fore-and-aft direction relative to the lower part, and is perpendicular to at least one cylinder axis Cy.

[0050] The EGR cooler path 52 and the thermostat 41 are arranged so that (i) at least condensed water generated in the EGR cooler path 52 returns to the exhaust path 30, and (ii) the upper part of at least one cylinder axis Cy is located forward of the lower part and the lowermost end of the rear side surface 11b forming a part of the intake path 20 is located above the lowermost end of the front side surface 11f forming a part of the exhaust path 30, among the four side surfaces 11f, 11b, 11r, and 11l of the cylinder portion 11. The cylinder section 11 is disposed above a second plane S2 that passes through the bottom end of the cylinder section 11 and is perpendicular to at least one cylinder axis Cy, below a third plane S3 that passes through the top end of the cylinder section 11 and is perpendicular to at least one cylinder axis Cy, and inside the bifurcated main frame section 3 as viewed in the axial direction of the head pipe 4 (direction of the axis P), so that any two of the three side surfaces excluding the left side surface 11l and the right side surface 11l are the side closest to the EGR cooler path 52 and the side closest to the thermostat 41, respectively. The following pattern A, pattern B, and pattern C are available as combinations of the positions of the EGR cooler path 52 and the thermostat 41 in this embodiment.

[0051] In pattern A, the EGR cooler path 52 is disposed such that the rear side surface 11b of the cylinder portion 11 is the side closest to the EGR cooler path 52. Note that the position of the EGR cooler path 52 in pattern A is not limited to the position of the EGR cooler path 52 shown in FIG. 1 . In pattern A, the thermostat 41 is disposed such that the side of the right side surface 11r or the left side surface 11l of the cylinder portion 11 that is closer to the camshaft drive mechanism 17, other than the right side surface 11r or the left side surface 11l, is the side closest to the thermostat 41, as in the thermostat 41a and the thermostat 41b shown in FIG. 1 . Alternatively, in pattern A, the thermostat 41 is disposed such that the front side surface 11f of the cylinder portion 11 is the side closest to the thermostat 41, as in the thermostat 41c and the thermostat 41d shown in FIG. 1 . In the side view of pattern A in Fig. 1, thermostat 41a is indicated by a solid line, and thermostats 41b, 41c, and 41d are indicated by two-dot chain lines. Thermostat 41a is directly attached to cylinder portion 11, and thermostats 41b, 41c, and 41d are connected to cylinder portion 11 via coolant piping (not shown). Note that the positions of thermostats 41 in pattern A are not limited to the positions of thermostats 41a, 41b, 41c, and 41d shown in Fig. 1.

[0052] In pattern B, the EGR cooler path 52 is arranged such that one of the right side surface 11r and the left side surface 11l of the cylinder portion 11, other than the right side surface 11r or the left side surface 11l that is closer to the camshaft drive mechanism 17, is the side closest to the EGR cooler path 52. Note that the position of the EGR cooler path 52 in pattern B is not limited to the position of the EGR cooler path 52 shown in FIG. 1. In pattern B, the thermostat 41 is arranged such that the front side surface 11f of the cylinder portion 11 is the side closest to the thermostat 41, for example, as in the thermostat 41c and the thermostat 41d shown in FIG. 1. Alternatively, in pattern B, the thermostat 41 is arranged such that the rear side surface 11b of the cylinder portion 11 is the side closest to the thermostat 41, for example, as in the thermostat 41e and the thermostat 41f shown in FIG. 1. In the side view of pattern B in Fig. 1, thermostat 41e is indicated by a solid line, and thermostats 41c, 41d, and 41f are indicated by two-dot chain lines. Thermostats 41c, 41d, 41e, and 41f are connected to cylinder portion 11 via coolant piping (not shown). Note that the positions of thermostats 41 in pattern B are not limited to the positions of thermostats 41c, 41d, 41e, and 41f shown in Fig. 1.

[0053] In pattern C, the EGR cooler path 52 is disposed such that the front side surface 11f of the cylinder portion 11 is the side closest to the EGR cooler path 52. Note that the position of the EGR cooler path 52 in pattern C is not limited to the position of the EGR cooler path 52 shown in FIG. 1 . In pattern C, the thermostat 41 is disposed such that the side of the right side surface 11r or the left side surface 11l of the cylinder portion 11 that is closer to the camshaft drive mechanism 17, other than the right side surface 11r or the left side surface 11l, is the side closest to the thermostat 41, as in the thermostat 41a and the thermostat 41b shown in FIG. 1 . Alternatively, in pattern C, the thermostat 41 is disposed such that the rear side surface 11b of the cylinder portion 11 is the side closest to the thermostat 41, as in the thermostat 41e and the thermostat 41f shown in FIG. 1 . In the side view of pattern C in Fig. 1, thermostat 41a is indicated by a solid line, and thermostats 41b, 41c, and 41d are indicated by two-dot chain lines. Thermostat 41a is directly attached to cylinder portion 11, and thermostats 41b, 41e, and 41f are connected to cylinder portion 11 via coolant piping (not shown). Note that the positions of thermostats 41 in pattern C are not limited to the positions of thermostats 41a, 41b, 41e, and 41f shown in Fig. 1.

[0054] In patterns A to C, when the thermostat 41 is connected to the cylinder portion 11 via a coolant pipe (not shown), the thermostat 41 may be connected to the cylinder head portion 14, may be connected to the cylinder body portion 13, or may be connected to both the cylinder head portion 14 and the cylinder body portion 13.

[0055] In FIG. 1 , the thermostat 41a is attached directly to the left side surface of the cylinder head portion 14. In patterns A and C, when the thermostat 41 is arranged so that the side surface of the right side surface 11r or the left side surface 11l of the cylinder portion 11 other than the right side surface 11r or the left side surface 11l closer to the camshaft drive mechanism 17 is the side surface closest to the thermostat 41, the thermostat 41 may be attached directly to the right side surface or the left side surface of the cylinder body portion 13. Also, in patterns A to C, when the thermostat 41 is arranged so that the front side surface 11f or the rear side surface 11b of the cylinder portion 11 is the side surface closest to the thermostat 41, the thermostat 41 may be attached directly to the cylinder body portion 13 or the cylinder head portion 14. Also, in patterns A to C, the thermostat 41 may be arranged inside the cylinder portion 11 without being exposed to the outside.

[0056] 1, the thermostats 41a, 41c, and 41e are located above the first plane S1, and the thermostats 41b, 41d, and 41f are located below the first plane S1. In patterns A to C, when the thermostat 41 is connected to the cylinder portion 11 via a coolant pipe, the thermostat 41 may be disposed so as to intersect with the first plane S1.

[0057] 1, the camshaft drive mechanism 17 is arranged in a space to the right of the center of the lean vehicle 1 in the left-right direction, and the thermostats 41c, 41d, 41e, and 41f, which are arranged so that the front side surface 11f or the rear side surface 11b of the cylinder portion 11 is the closest side, are arranged in a space to the left of the center of the lean vehicle 1 in the left-right direction. In patterns A to C, when the thermostat 41 is arranged so that the front side surface 11f or the rear side surface 11b of the cylinder portion 11 is the closest side to the thermostat 41, the thermostat 41 may be arranged in a position that passes through the center of the lean vehicle 1 in the left-right direction, or may be arranged in the space where the camshaft drive mechanism 17 is arranged, either in the space to the right or the space to the left of the center of the lean vehicle 1 in the left-right direction.

[0058] 1, the entire EGR path 50 including the EGR cooler path 52 is disposed above the first plane S1 and below the third plane S3. A portion of the EGR path 50 may be disposed above the third plane S3.

[0059] 1 , the EGR cooler path 52 in patterns A to C is arranged to face the first cylinder head side surface of the cylinder head portion 14 in a direction perpendicular to at least one cylinder axis Cy, so that a first cylinder head side surface, which is one of three side surfaces of the cylinder head portion 14 excluding the right side surface or the left side surface close to the camshaft drive mechanism 17, is the side surface closest to the EGR cooler path 52. The EGR cooler path 52 in patterns A to C may be arranged at a position close to the first cylinder head side surface inside the cylinder head portion 14, so that the first cylinder head side surface, which is one of three side surfaces of the cylinder head portion 14 excluding the right side surface or the left side surface close to the camshaft drive mechanism 17, is the side surface closest to the EGR cooler path 52. For example, as shown in Fig. 2 , in pattern B, the EGR cooler path 52 may be arranged inside the cylinder head 14 so that one of the right side surface 11r and the left side surface 11l of the cylinder portion 11 other than the right side surface 11r or the left side surface 11l closer to the camshaft drive mechanism 17 is the side closest to the EGR cooler path 52. In Fig. 2 , the EGR path 50 is connected to the exhaust path 30 inside the cylinder head 14, but it may also be connected to the exhaust path 30 outside the cylinder head 14. Furthermore, although not shown, in patterns A and C, the EGR cooler path 52 may be arranged inside the cylinder head 14 so that the front side surface 11f or the rear side surface 11b of the cylinder portion 11 is the side closest to the EGR cooler path 52.

[0060] 1, at least one EGR path exhaust side end 50a of the EGR path 50 is connected to the exhaust path 30 outside the cylinder head portion 14, but may be connected to the exhaust path 30 inside the cylinder head portion 14. In FIG. 1, the EGR path 50 is connected to the intake path 20 outside the cylinder head portion 14, but may be connected to the intake path 20 inside the cylinder head portion 14.

[0061] Second Embodiment Next, a lean-fuel vehicle 1 according to a second embodiment of the present invention will be described with reference to FIG. 3 . The lean-fuel vehicle 1 according to the second embodiment has all of the configurations of the first embodiment. The positions of the EGR cooler path 52 and the thermostat 41 in the second embodiment are not limited to those shown in FIG. 3 . In FIG. 3 , the thermostat 41 is connected to a radiator 42 disposed forward of at least one cylinder axis Cy in the vehicle longitudinal direction. While FIG. 3 is a side view of the lean-fuel vehicle 1, the main frame 3 is shown in cross section cut along a plane passing through the center of the lean vehicle 1 in the vehicle transverse direction.

[0062] The lean-fuel vehicle 1 of the second embodiment has a turbocharger 61. The turbocharger 61 may be an electrically assisted turbocharger that can pressurize air using exhaust gas pressure and an electric motor. A portion of the intake path 20 is formed inside the turbocharger 61. A portion of the exhaust path 30 is formed inside the turbocharger 61. An intercooler 62 that cools the air pressurized by the turbocharger 61 is provided in the intake path 20. The turbocharger 61 and the intercooler 62 are disposed forward of at least one cylinder axis Cy in the vehicle longitudinal direction. A portion of the intake path 20 downstream of the intercooler 62 is disposed above the engine 10 in the vehicle vertical direction.

[0063] A throttle valve 63 is disposed in the intake path 20 to adjust the amount of air supplied to at least one combustion chamber 12. The throttle valve 63 is disposed downstream of the intercooler 62 in the airflow direction. The intake path 20 is also provided with a first pressure sensor 64 and a second pressure sensor 65 for detecting the pressure of the air in the intake path 20. The first pressure sensor 64 is disposed downstream of the throttle valve 63 in the airflow direction. The second pressure sensor 65 is disposed upstream of the throttle valve 63 and downstream of the intercooler 62 in the airflow direction. A control device (not shown) provided in the lean-fuel vehicle 1 may detect a pressure difference between the air upstream of the throttle valve 63 and the air downstream of the throttle valve 63 based on signals from the two pressure sensors 64 and 65. The control device may estimate the amount of air supplied to at least one combustion chamber 12 from this pressure difference. The second pressure sensor 65 may be configured to detect temperature in addition to pressure. The throttle valve 63, the first pressure sensor 64, and the second pressure sensor 65 are disposed above the engine 10 in the vehicle vertical direction. When the lean vehicle 1 is viewed in the vehicle left-right direction, a portion of the intake path 20 downstream of the intercooler 62 overlaps with the main frame portion 3. This portion of the intake path 20 is disposed inside the bifurcated main frame portion 3.

[0064] The above-described layout of the turbocharger 61 and the portion of the intake path 20 downstream of the intercooler 62 in the second embodiment may be applied to a lean vehicle having a turbocharger that is not included in the lean vehicle of the present invention. For example, it may be applied to a lean vehicle that does not have an EGR path.

[0065] 1: lean vehicle, 2: body frame, 3: main frame portion, 4: head pipe, 10: engine, 11: cylinder portion, 11b, 11f, 11l, 11r: side surface of cylinder portion, 12: combustion chamber, 13: cylinder body portion, 14: cylinder head portion, 15: cylinder bore, 16: crankshaft, 17: camshaft drive mechanism, 18: camshaft, 20: intake path, 30: exhaust path, 40: engine coolant path, 41, 41a, 41b, 41c, 41d, 41e, 41f: thermostat, 50: EGR path, 50a: exhaust side end of EGR path, 51: EGR cooler, 52: EGR cooler path, Cy: cylinder axis, S1: first plane, S2: second plane, S3: third plane

Claims

1. (A) (A1) an engine having a head pipe aligned in the vertical direction of the vehicle, a main frame portion having a bifurcated shape from the head pipe when viewed in the axial direction of the head pipe, (A2) a body frame that tilts to the right of the vehicle when turning right and tilts to the left of the vehicle when turning left; (B) (B1) an engine having a cylinder portion that includes a cylinder body portion that forms at least one cylinder hole, and a cylinder head portion that is connected to the cylinder body portion and constitutes an end of the engine in the direction of at least one cylinder axis that is the central axis of the at least one cylinder hole, and that forms at least one combustion chamber; (B2) a crankshaft that rotates around an axis that is aligned in the left-right direction of the vehicle; and (B3) a camshaft drive mechanism that is disposed inside the engine so as to be located to the right or left of the at least one cylinder hole formed in the cylinder body portion in the left-right direction of the vehicle, and that transmits the drive force of the crankshaft to at least one camshaft disposed inside the cylinder head portion; (C) A lean-fuel vehicle comprising: an intake path connected to the at least one combustion chamber and an exhaust path connected to the at least one combustion chamber, and an EGR path connecting the intake path and the exhaust path for returning a portion of exhaust gas passing through the exhaust path to the intake path, the lean-fuel vehicle further comprising an engine coolant path provided with a thermostat and through which a coolant other than lubricating oil flows, the thermostat being disposed inside the main frame portion having a bifurcated shape as viewed in the axial direction of the head pipe, the EGR path including an EGR cooler path formed within an EGR cooler disposed inside the main frame portion having a bifurcated shape as viewed in the axial direction of the head pipe, the EGR path including an EGR cooler path having a lowermost end located above a lowermost end of at least one exhaust side end of the EGR path connected to the exhaust path in the EGR path, the entire EGR path including the EGR cooler path being disposed above a first plane that passes through an uppermost end of the cylinder body portion disposed such that an upper portion of the at least one cylinder axis is located forward in the vehicle longitudinal direction relative to a lower portion, The EGR cooler path and the thermostat area cylinder section arranged so that (i) at least the EGR cooler path returns to the exhaust path, and (ii) an upper part of the at least one cylinder axis is located forward of a lower part and a lowermost end of a rear side surface forming a part of the intake path is located higher than a lowermost end of a front side surface forming a part of the exhaust path, and any two of three side surfaces, excluding a right side surface or a left side surface close to the camshaft drive mechanism, are the side closest to the EGR cooler path and the side closest to the thermostat, respectively, above a second plane passing through the bottom end of the cylinder section and perpendicular to the at least one cylinder axis, below a third plane passing through the top end of the cylinder section and perpendicular to the at least one cylinder axis, and inside the main frame section which is bifurcated when viewed in the axial direction of the head pipe.

2. The lean vehicle described in claim 1, characterized in that the entire EGR path including the EGR cooler path is positioned above the first plane that passes through the uppermost end of the cylinder body section arranged so that the upper part of the at least one cylinder axis is located forward of the lower part, and is perpendicular to the at least one cylinder axis, and is positioned below the third plane that passes through the uppermost end of the cylinder section and is perpendicular to the at least one cylinder axis.

3. The lean vehicle described in claim 2, characterized in that the EGR cooler path is arranged to face the first cylinder head side surface of the cylinder head portion in a direction perpendicular to the at least one cylinder axis, or is arranged in a position close to the first cylinder head side surface inside the cylinder head portion, so that a first cylinder head side surface, which is one of three side surfaces excluding the right side surface or the left side surface close to the camshaft drive mechanism, of the cylinder head portion included in the cylinder portion arranged so that the upper part of the at least one cylinder axis is located forward of the lower part, is the side surface closest to the EGR cooler path.

Images