JP2017223193A - Engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve compact layout of a bypass passage while suppressing an in-cylinder difference of intake efficiency in an engine with a turbocharger having a bypass passage which bypasses the turbocharger.SOLUTION: In an engine 1, a supercharger 50 disposed on a lateral side of an attachment face 10a, an intercooler 60 disposed below the supercharger 50, and a distribution passage 70 are provided in an intake passage 30 in this order from upstream side. A bypass passage 80 which is formed so as to connect a branch part 34c positioned upstream of the supercharger 50 to a merging part 65 positioned between a core 61 and the distribution passage 70 is provided in the intake passage 30. The branch part 34c is positioned at one side in a cylinder row direction with respect to the supercharger 50 on a lateral side of the attachment face 10a. The merging part 65 is disposed on an outer surface of the branch part 34s in a cooler housing 63, and communicates with a downstream side portion S2 with respect to the core 61 in the cooler housing 63.SELECTED DRAWING: Figure 6

Description

  The technology disclosed herein relates to an engine with a supercharger.

  For example, Patent Document 1 describes an engine including a supercharger. Specifically, this Patent Document 1 describes a four-cylinder engine including a supercharger and a distribution passage (intake chamber). Both the supercharger and the distribution passage are provided on one side of the engine body. It is arranged on the side (rear side). The distribution passage according to Patent Document 1 functions as a chamber that temporarily stores supercharged air, and is configured to supply air to an independent passage for each cylinder.

  Patent Document 2 describes an air intake device including an intercooler. The intercooler according to Patent Document 2 is assembled on one side (front side) of the engine body, and includes a core having an air cooling function and a housing (chamber portion) that accommodates the core.

JP 2014-25476 A Japanese Unexamined Patent Publication No. 2013-147953

  By the way, in an engine with a supercharger, it is known that a portion on the upstream side of the supercharger and a portion on the downstream side of the intercooler in the intake passage are connected by a bypass passage configured to bypass the supercharger. It has been. In this case, since the number of parts increases by the amount of the bypass passage, it is required to lay out the bypass passage as compactly as possible so that the entire engine is not bulky.

  In order to satisfy such a requirement, for example, it is conceivable to connect the downstream end of the bypass passage to a distribution passage as described in Patent Document 1, but such a structure has an intake efficiency between cylinders. This is inconvenient in achieving both suppression of the difference and downsizing of the bypass passage.

  That is, the distribution passage is required to evenly distribute the intake air to each cylinder so that the intake efficiency is uniform among the cylinders, but depending on the connection location with the bypass passage, the intake air that has passed through the bypass passage There is a risk of being distributed to a specific cylinder.

  Therefore, in order to distribute the intake air evenly, the bypass passage may be connected to a specific portion in the distribution passage, for example, when the distribution passage extends in the cylinder row direction, to the central portion in the cylinder row direction. It is done. However, if the bypass passage is turned around from the lower side or side of the distribution passage in order to connect to such a location, it may interfere with the passage for intake air that has passed through the supercharger, or the engine may be bulky to the side. Is inconvenient. In particular, when the distribution passage is arranged in the gap between the supercharger and the engine body, the bypass passage also needs to be arranged in the gap. In this case, the supercharger is provided by the space for arranging the bypass passage. Since it is required that the clearance between the engine body and the engine body be wide, the turbocharger protrudes to the side and the engine becomes bulky to the side, which is inconvenient. In addition, the distribution passage is normally a member connected to the intake port in the vicinity of the upper end of the engine body. Therefore, if the bypass passage is turned from above the distribution passage, the bypass passage protrudes from the upper end of the engine body. This is inconvenient because the engine is bulky in the height direction.

  The technology disclosed herein has been made in view of such a point, and an object thereof is to provide an intake efficiency in an engine with a supercharger having a bypass passage configured to bypass the supercharger. It is to lay out the bypass passage in a compact manner while suppressing the difference between the cylinders.

  The technology disclosed herein comprises an engine body having a plurality of cylinders, and an intake passage disposed outside the engine body and connected to each of the plurality of cylinders via an intake port, The intake passage is provided with a supercharger and an intercooler disposed downstream in the flow direction of intake air with respect to the supercharger. The intercooler includes a core, and a cooler housing that houses the core. The present invention relates to an engine with a supercharger configured to include

  The supercharger is arranged on the side of the intake side that is the side of the engine body where the upstream end of the intake port is open, while the intercooler is The supercharger and the intercooler are arranged so that at least a part of each of the supercharger and the intercooler overlap each other when the engine main body is viewed from above, and the intercooler in the intake passage is disposed. A distribution passage configured to distribute the intake air that has passed through the intercooler to each of the plurality of cylinders is further provided in the downstream side portion.

  The air intake passage is also provided with a branch portion disposed in the upstream portion of the air intake passage from the turbocharger between the core and the distribution passage in the air intake passage. A bypass passage configured to be connected to the merging portion is provided, and the branch portion is disposed on one side of a cylinder row direction with respect to the supercharger on a side of the side surface on the intake side. The merging portion is disposed on the outer surface of the cooler housing on the branching portion side, and communicates with the downstream portion of the core in the cooler housing.

  Here, the “core” indicates a member configured to cool the intake air passing therethrough.

  According to this configuration, since the supercharger and the intercooler are disposed on the side surface on one side of the engine body, the bypass passage can be provided along the same side surface. This is effective in laying out the bypass passage in a compact manner.

  Further, according to the above configuration, the branch portion is disposed on one side in the cylinder row direction with respect to the supercharger. On the other hand, an intercooler is disposed below the supercharger, and the merging portion is disposed on the outer surface of the cooler housing on the branching portion side. Therefore, the bypass passage extends along the mounting surface in the space on one side in the cylinder row direction with respect to the supercharger. That is, the bypass passage is monotonically extended from the upper side to the lower side along the mounting surface starting from the branch portion, and then connected to the junction provided on the outer surface of the cooler housing. As described above, the configuration in which the bypass passage is connected to the outer surface on the side of the branching portion without turning around the cooler housing from the lower side, the side, or the upper side is particularly suitable for the bypass passage directly to the distribution passage. Compared to the connected configuration, this is effective in laying out the bypass passage in a compact manner.

  Further, such a configuration is effective in preventing the bypass passage from protruding from the upper end of the engine body, and thus making the entire engine compact in the height direction.

  Further, the passage connecting the intercooler and the distribution passage among the intake passages is usually configured in consideration of the distribution performance of the intake air. Since the merging portion communicates with a portion downstream of the core in the cooler housing, the intake air that has passed through the bypass passage passes through the passage configured in consideration of the distribution performance as described above. Will flow in. As a result, it is possible to suppress the difference between the cylinders in the intake efficiency due to the intake air that has passed through the bypass passage.

  Therefore, according to the above configuration, the bypass passage can be laid out in a compact manner while suppressing the difference in intake efficiency between the cylinders.

  Furthermore, the said junction part is good also as extending from the outer surface by the side of the said branch part in the said cooler housing to the outer surface on the opposite side to a supercharger.

  For example, when it is provided on the upper surface of the cooler housing at the junction, it is necessary to separate the intercooler and the supercharger up and down as much as a space for providing the junction is ensured. This is inconvenient when the engine is configured to be compact in the height direction.

  On the other hand, according to the above configuration, it is advantageous to bring the intercooler and the supercharger close up and down by providing the merging portion from the outer surface on the branching portion side to the outer surface on the opposite side of the supercharger. As a result, it is advantageous to make the engine compact in the height direction.

  Further, the engine body is provided with an intake opening that opens to each of the plurality of cylinders and a downstream end of the intake passage, and is formed for each cylinder so as to connect the downstream end to the intake opening. An intake port, and an upstream end of the intake port is opened along the cylinder row direction on the mounting surface, and the distribution passage covers the upstream end of the intake port, respectively. Thus, it is good also as extending in the cylinder row direction.

  Further, the intercooler is attached to the mounting surface at a predetermined interval, and an introduction passage that is a portion of the intake passage that connects the intercooler to the distribution passage is connected to the intercooler. It may be interposed between the engine body.

  According to this configuration, since the introduction passage is provided in the gap between the intercooler and the engine main body, it is advantageous to make the intake passage and thus the entire engine compact.

  Further, the introduction passage may be connected to a central portion of the distribution passage in the cylinder row direction.

  According to this configuration, the difference in intake efficiency between cylinders due to intake air that has passed through the introduction passage, that is, intake air that has been supercharged by the supercharger immediately after passing through the core, or intake air that has passed through the bypass passage is reduced. It becomes possible to do.

  Further, when the intake passage is viewed from the front along the intake / exhaust direction, the central axis of the flow path formed by the portion extending from the bypass passage to the introduction passage is convex downward. It may be curved.

  This configuration is advantageous in reducing the ventilation resistance of intake air that bypasses the supercharger.

  As described above, according to the above-described engine with a supercharger, the junction portion of the bypass passage is disposed on the outer surface on the branching portion side in the cooler housing, so that the bypass passage can be suppressed while suppressing the difference in intake efficiency between the cylinders. Can be laid out compactly.

It is the schematic which abbreviate | omits and shows a structure of an engine with a supercharger. It is a perspective view of an engine with a supercharger. It is a front view which shows the engine with a supercharger seeing from the front side. It is a top view of an engine with a supercharger. It is a perspective view which shows the whole structure of an intake passage. FIG. 3 is a front view showing a partially broken configuration of the rear side of the intake passage. It is a side view of an intake passage. It is a cross-sectional view of an intake passage. It is a longitudinal cross-sectional view of an intake passage. It is a front view which shows a 3rd channel | path and a distribution channel seen from the front side. It is a cross-sectional view of a distribution passage. It is a perspective view which shows a distribution channel partially across.

  Hereinafter, an embodiment of an engine with a supercharger will be described based on the drawings. The following description of preferred embodiments is exemplary.

<Overall engine configuration>
FIG. 1 shows a schematic configuration of a supercharged engine (hereinafter simply referred to as “engine”) according to an embodiment. 2 is a perspective view of the engine, FIG. 3 is a front view of the engine, and FIG. 4 is a plan view of the engine. The engine 1 is a gasoline engine mounted on a front engine / front drive type vehicle, and includes a mechanically driven supercharger (so-called supercharger) 50 as shown in FIGS. .

  As shown in FIG. 4, the engine 1 includes four cylinders 18 arranged in a row, and the so-called series is mounted so that the four cylinders 18 are arranged along the vehicle width direction. It is configured as a 4-cylinder horizontal engine. As a result, in the present embodiment, the engine longitudinal direction, which is the arrangement direction (cylinder row direction) of the four cylinders 18, substantially coincides with the vehicle width direction, and the engine width direction substantially coincides with the vehicle longitudinal direction. Hereinafter, unless otherwise specified, the front side is one side in the engine width direction (the intake side in the intake and exhaust directions, and in the case of a horizontally mounted engine, the front side in the vehicle longitudinal direction), and the rear side is the other side in the engine width direction. Side (exhaust side in the intake / exhaust direction, and in the case of a horizontally mounted engine, the rear side of the vehicle front-rear direction), and the left side is one side of the engine front-rear direction (one side in the cylinder row direction, which is a horizontally mounted engine) In this case, the right side refers to the other side in the longitudinal direction of the engine (the other side in the cylinder row direction, and in the case of a horizontally mounted engine, the right side in the vehicle width direction).

  As shown in FIG. 1, the engine 1 is mainly disposed in an engine body 10 having four cylinders 18 (only one cylinder is shown in FIG. 1), and on the front side (outside) of the engine body 10. An intake passage 30 connected to each cylinder 18 through 16, and an exhaust passage (shown only in FIG. 1) 40 disposed on the rear side of the engine body 10 and connected to each cylinder 18 through an exhaust port 17. (A so-called front intake rear exhaust engine). The supercharger 50 is disposed on the intake passage 30. As shown in FIGS. 2 to 3, on the intake side (front side) of the engine body 10, in addition to the intake passage 30, a drive pulley 53 for the supercharger 50 and an alternating current used in the electrical system are supplied. An alternator 91 that is generated, an air compressor 92 for air conditioning, a starter motor 93 that drives the engine main body 10 until a complete explosion at the start, a fuel pump 96 that constitutes a fuel supply system 95, and the like are arranged.

  The engine body 10 is configured to burn the air-fuel mixture of intake air and fuel supplied from the intake passage 30 in the cylinder 18. Specifically, the engine body 10 is disposed on a cylinder block 11 provided with four cylinders 18, a cylinder head 12 assembled on the cylinder block 11, and a lower side of the cylinder block 11. And a stored oil pan 13. A piston 14 connected to the crankshaft 15 via a connecting rod 141 is fitted in each cylinder 18 so as to be able to reciprocate.

  In the cylinder block 11, four cylinders 18 are arranged in series. In the following description, the four cylinders 18 shown in FIG. 4 may be referred to as the first cylinder 18a, the second cylinder 18b, the third cylinder 18c, and the fourth cylinder 18d in order from the right side along the cylinder row direction. .

  The cylinder head 12 is formed with two intake ports 16 and two exhaust ports 17 for each cylinder 18, and an intake valve 21 that opens and closes an opening on the cylinder 18 side in the intake port 16 and the exhaust port 17. And the exhaust valve 22 is arrange | positioned at each. FIG. 4 shows the configuration of the intake port 16 associated with the second cylinder 18b. Specifically, the cylinder head 12 according to the present embodiment is provided with an intake port 16a that opens to each of the four cylinders 18, and a downstream end (specifically, an independent passage 72) of the intake passage 30, and Two intake ports 16 formed for each cylinder 18 are provided for each cylinder 18 so as to connect the downstream end to the intake port 16a. The upstream end 16b of the intake port 16 is opened side by side along the cylinder row direction on a mounting surface 10a described later. The distribution passage 70 extends in the cylinder row direction so as to communicate with the upstream end 16b of the intake port 16 of each cylinder 18 and to cover the upstream end 16b. An intake valve 21 that opens and closes each of the eight intake ports 16 is driven by an intake camshaft provided in the cylinder head 12. Specifically, when the intake camshaft rotates, turning force acts on the upper end portion of the intake valve 21 via the cam of the intake camshaft. The intake valve 21 is driven to open and close the intake port by its rotational force. The same applies to the exhaust side.

  The cylinder head 12 is also provided with an injector 98 for injecting fuel supplied from the fuel tank into the cylinder 18 for each cylinder 18. The fuel tank and the injector 98 are connected to each other by a fuel supply path. A fuel supply system 95 including a fuel pump 96 and a common rail 97 and capable of supplying fuel to the injector 98 at a relatively high fuel pressure is provided on the fuel supply path. The fuel pump 96 pumps fuel from the fuel tank to the common rail 97, and the common rail 97 can store the pumped fuel at a relatively high fuel pressure. When the injector 98 is opened, the fuel stored in the common rail 97 is injected from the injection port of the injector 98.

  The intake passage 30 is configured to allow intake air (fresh air) introduced from the outside to pass through and to be supplied into the cylinder 18 of the engine body 10. Specifically, on the intake passage 30, an air cleaner 31 (illustrated only in FIG. 1) that purifies intake air introduced from the outside in order from the upstream side along the flow direction of intake air, and the flow rate of the intake air that passes therethrough is adjusted. There are provided a throttle valve 32 for performing the operation, a mechanically driven supercharger 50 configured to compress intake air, and an intercooler 60 configured to be able to adjust the temperature of the intake air.

  The downstream end of the intake passage 30 is constituted by a distribution passage 70 that supplies intake air to each cylinder 18. The distribution passage 70 includes a surge tank 71 that temporarily stores air and an independent passage 72 that distributes the air stored in the surge tank 71 to each cylinder 18.

  In addition, as a passage connecting the respective parts on the intake passage 30, the intake passage 30 is disposed on the downstream side of the air cleaner 31, and the first passage 34 that guides the intake air purified by the air cleaner 31 to the supercharger 50, The second passage 35 guides the intake air compressed by the feeder 50 to the intercooler 60, and the third passage 36 guides the air that has passed through the intercooler 60 to the distribution passage 70.

  Further, the intake passage 30 is configured to be branched upstream of the supercharger 50 and to merge downstream of the supercharger 50 and the intercooler 60. Specifically, the portion of the intake passage 30 between the throttle valve 32 and the supercharger 50 is connected to the portion of the intake passage 30 between the intercooler 60 and the distribution passage 70. A bypass passage 80 is provided. A bypass valve 81 that can open and close the bypass passage 80 is disposed in the bypass passage 80.

  The exhaust passage 40 is configured to exhaust the exhaust generated in the cylinder 18 to the outside. Specifically, the upstream portion of the exhaust passage 40 is an exhaust manifold having an independent passage branched for each cylinder 18 and connected to the outer end of the exhaust port 17 and a collecting portion where each of the independent passages gathers. (Not shown). On the downstream side of the exhaust manifold in the exhaust passage 40, exhaust purification catalysts 41 and 42 that purify harmful components in the exhaust are connected.

  Hereinafter, the configuration of the intake side (front side) of the engine 1, particularly, the three-dimensional structure of the intake passage 30 will be described.

<Intake side configuration>
5 is a perspective view showing the configuration of the intake passage 30, FIG. 6 is a front view showing a partially broken configuration of the rear side of the intake passage 30, and FIG. 7 is a side view of the intake passage 30. FIG. 8 is a transverse sectional view of the intake passage 30, and FIG. 9 is a longitudinal sectional view of the intake passage 30 (longitudinal sectional view when viewed in the crankshaft direction).

  Each part constituting the intake passage 30 is disposed on the front side of the engine body 10, specifically, on the side (front) of the front side surface 10a of the engine body 10 (FIGS. 2 to 4 and FIG. (See FIG. 12). Hereinafter, the side surface on the intake side of the engine body 10 (specifically, the side surface of the engine body 10 to which the intake passage 30 is connected) 10a is referred to as a mounting surface 10a. As shown in FIG. 3 and the like, the mounting surface 10a is configured by the cylinder block 11 and the front side surface of the cylinder head 12. As will be described later, the supercharger 50 is disposed at a predetermined interval I1 with respect to the mounting surface 10a. By providing such an interval I1, a gap is provided between the rear surface of the supercharger 50 and the mounting surface 10a. The first passage 34 extends along the cylinder row direction on the left side of the supercharger 50 and is connected to the left end of the supercharger 50. Further, the intercooler 60 is adjacent to the supercharger 50 in the vertical (gravity direction) downward direction, and is arranged with a predetermined interval I2 with respect to the mounting surface 10a, similarly to the supercharger 50. ing. The intercooler 60 is disposed so as to overlap the supercharger 50 when the engine body 10 is viewed from above. In the present embodiment, the intercooler 60 is disposed so as to be covered from above by the supercharger 50, but is not limited thereto. The supercharger 50 and the intercooler 60 should just be arrange | positioned so that each at least one part may mutually overlap when the engine main body 10 is seen from upper direction. Further, the intercooler 60 is arranged side by side with the fuel pump 96. The second passage 35 extends vertically so as to connect the front part of the supercharger 50 and the front part of the intercooler 60. The distribution passage 70 is located in the gap between the supercharger 50 and the mounting surface 10a, and the third passage 36 is connected from the intercooler 60 to the supercharger 50 so as to connect the distribution passage 70 to the intercooler 60. It is extended along the clearance gap between the part over and the attachment surface 10a. The bypass passage 80 extends downward from the middle of the first passage 34, extends inward (rightward) of the engine body 10, and is connected to the left side portion of the intercooler 60.

  Next, the structure and arrangement of each part will be described in detail.

  The first passage 34 is generally formed in a tubular shape extending in the cylinder row direction (left and right), and its upstream end (left end) is constituted by a throttle body 34a in which the throttle valve 32 is built. The throttle body 34a is formed in a metal short cylinder, and as shown in FIGS. 3 to 6 and the like, the throttle body 34a is positioned to the left and forward of the mounting surface 10a with the opening at both ends directed to the left and right. Are arranged to be. An air cleaner 31 is connected to the upstream end (left end) of the throttle body 34a through a passage (not shown), while the downstream end (right end) of the throttle body 34a is a second portion of the first passage 34. A one-passage body 34b is connected.

  As shown in FIGS. 3 to 6, the first passage main body 34 b is configured to connect the throttle body 34 a to the supercharger 50. Specifically, the first passage main body 34b is formed in a long tube shape made of resin with openings at both ends directed to the left and right. The first passage main body 34b is disposed so as to be positioned on the upper side of the mounting surface 10a and in front of the left side portion and coaxial with the throttle body 34a. More specifically, as shown in FIG. 6, the first passage body 34b is formed so as to expand in a substantially tapered shape from the outside in the cylinder row direction toward the inside (from the left side to the right side). The downstream end of the throttle body 34a is connected to the upstream end (left end) of the first passage body 34b, while the suction port of the supercharger 50 is connected to the downstream end (right end).

  The first passage body 34b has a branching portion 34c that branches to the bypass passage 80. As shown in FIG. 6, the branch portion 34 c is formed on the lower surface of the upstream side portion of the first passage body 34 b and is connected to the upstream end of the bypass passage 80. As shown in FIG. 4 to FIG. 6 and the like, the branch portion 34c is in the vehicle width direction with respect to the supercharger 50, the intercooler 60, the eight intake ports 16, and the distribution passage 70 connected to each intake port 16. Located outside (left side).

  Therefore, the intake air purified by the air cleaner 31 and flowing into the first passage 34 passes through the throttle valve 32 and is then sucked into the supercharger 50 from the downstream end of the first passage body 34b (see the arrow A1 in FIG. 6). Or flow into the bypass passage 80 via the branching portion 34c in the middle of the first passage main body 34b.

  The supercharger 50 is configured as a roots type supercharger. Specifically, the supercharger 50 includes a pair of rotors (not shown) having a rotation shaft extending along the cylinder row direction, a casing 52 that houses the rotor, and a drive pulley 53 that rotationally drives the rotor. It is connected to the crankshaft 15 via a drive belt (not shown) wound around the drive pulley 53.

  The casing 52 is formed so as to extend in the cylinder row direction (left and right) along the mounting surface 10a, and partitions the rotor accommodation space and the intake air flow path that passes through the supercharger 50. Specifically, the casing 52 is formed in a metal square tube shape whose left end and front surface are opened in the cylinder row direction, and as shown in FIG. Is arranged so as to be spaced from the first passage 34 by a predetermined distance (see FIG. 9) I1. At the left end of the casing 52 in the longitudinal direction, an intake port for sucking intake air compressed by the rotor is opened, and the downstream end (right end) of the first passage 34 is connected. On the other hand, as shown in FIG. 9, a discharge port 52b for discharging the intake air compressed by the rotor is opened on the front surface of the casing 52 (on the side opposite to the engine body 10). The upstream end (upper end) of 35 is connected.

  Here, as shown in FIGS. 4 to 6, one end side (right end side) and the other end side (left end side) of the supercharger 50 are fastened to the distribution passage 70. Specifically, a right end bracket 52R having a bolt insertion hole projects from the right end portion of the rear surface of the casing 52 (side surface on the engine body side), while the right end bracket 52R protrudes from the left end portion of the rear surface of the casing 52. A left end side bracket 52L configured in the same manner as in FIG. Both the bolt insertion hole of the right end side bracket 52R and the bolt insertion hole of the left end side bracket 52L are formed so that the bolts are inserted downward from above (see also FIG. 14).

  In addition, as shown in FIGS. 5 and 9, the supercharger 50 is also fastened to the third passage 36. Specifically, a pair of central brackets 52 </ b> C, each having a bolt insertion opening, are provided in a projecting manner at a substantially central portion in the left-right direction on the rear surface of the casing 52. The bolt insertion port of the central bracket 52C is formed so that the bolt is inserted in the cylinder row direction. One bracket 52C supports the base end side portion of the inserted bolt, while the other bracket 52C is The tip side portion of the same bolt is supported.

  The drive pulley 53 is configured to rotationally drive the rotor accommodated in the casing 52. Specifically, the drive pulley 53 is formed in an axial shape that protrudes from the right end of the casing 52 and extends substantially coaxially with respect to the first passage 34 and the casing 52. A drive belt is wound around the tip of the drive pulley 53, and the crankshaft 15 is configured to be drivingly connected to the supercharger 50 as described above.

  Therefore, during the operation of the engine 1, the output from the crankshaft 15 is transmitted through the drive belt and the drive pulley 53 to rotate the rotor. By rotating the rotor, the intake air sucked from the first passage 34 is compressed and discharged from the discharge port 52b. The discharged intake air flows into the second passage 35 disposed on the front side of the casing 52.

  The 2nd channel | path 35 is comprised so that the supercharger 50 may be connected to the intercooler 60, as shown in FIGS. As described above, since the supercharger 50 and the intercooler 60 are adjacent to each other in the vertical direction, the second passage 35 according to the present embodiment is formed so as to extend along the vertical direction of the engine. The second passage 35 is formed such that both upper and lower ends are curved toward the engine body side (rear side) when viewed in the cylinder row direction, and the upper end is a front portion of the casing 52 of the supercharger 50. While being connected to (discharge port 52b), the lower end is connected to the front part of intercooler 60. Specifically, the second passage 35 is formed as a resin curved pipe portion that is flat on the left and right (cylinder row direction), and from the discharge port 52b of the casing 52 to the engine as shown in FIGS. It extends downward while curving so as to protrude toward the opposite side (front side) of the main body 10, and is connected to the front part of the intercooler 60. More specifically, a portion near the upper end of the second passage 35 extends so as to cover a part of the front surface of the supercharger 50, so that the upper end of the second passage 35 is located in front of the supercharger 50. The space partitioned by is positioned. Similarly, a portion in the vicinity of the lower end of the second passage 35 extends so as to cover a part of the front surface of the intercooler 60, so that the lower portion of the second passage 35 is formed in front of the intercooler 60. Space is located.

  Therefore, as shown by an arrow A2 in FIG. 9, the intake air flowing into the second passage 35 from the supercharger 50 flows forward from the supercharger 50 side, and then flows downward along the second passage 35. It flows toward the intercooler 60 and then flows backward toward the intercooler 60. The intake air that has passed through the second passage 35 flows into the intercooler 60 from the front side.

  Further, since the supercharger 50 and the intercooler 60 are connected by the second passage 35, the vertical relative movement between the supercharger 50 and the intercooler 60 is regulated.

As shown in FIGS. 7 to 8 and the like, the intercooler 60 is configured as a water-cooled intercooler, and is attached to the side of the core 61 and the core 61 having a cooling function of the intake air. A water supply pipe 62 a for introducing cooling water, a core connecting part 62 configured to support a drain pipe 62 b for extracting cooling water from the core 61, and a cooler housing 63 for accommodating the core 61 are provided.
As shown in FIG. 6, the dimension Wi in the width direction (left-right direction) of the intercooler 60 is shorter than the dimension Ws in the width direction of the supercharger 50.

  As shown in FIGS. 8 to 9 and the like, the core 61 is formed in a rectangular shape, and is disposed so that one side surface (rear surface) thereof faces the mounting surface 10a. While the front surface of the core 61 forms an intake air inflow surface, the rear surface of the core 61 forms an intake air outflow surface, and each of the cores 61 is the widest surface. In the core 61, a plurality of water tubes having a flat cylindrical shape made of a thin plate material are arranged, and corrugated corrugated fins are connected to the outer wall surface of each water tube by brazing or the like. With this configuration, the cooling water introduced from the water supply pipe 62a is supplied to each water tube to cool the hot intake air, while the cooling water heated by cooling the intake air is The water tubes are led out through the drain pipes 62b. Further, by providing the corrugated fins, the surface area of each water tube is increased and the heat dissipation effect is improved.

  As shown in FIGS. 6 to 8, the core connecting portion 62 is a rectangular thin plate-like member, is attached to the right side surface of the core 61, and is configured to connect the water supply pipe 62 a and the drain pipe 62 b to the water tube. Has been. The core connection part 62 partitions the right side surface of the intercooler 60 and the right side wall part of the accommodation space S1 of the core 61.

  The cooler housing 63 is a flow that joins the housing space S1 of the core 61, the flow path interposed between the second path 35 and the third path 36 in the intake path 30, and the bypass path 80 to the intake path 30. The road is partitioned. Specifically, the cooler housing 63 is arranged at a position below the casing 52 of the supercharger 50 with a predetermined interval (see FIG. 9) I2 from the mounting surface 10a of the engine body 10 in the same manner as the casing 52. Has been. More specifically, the cooler housing 63 is formed in a substantially box shape, and its rear surface faces the mounting surface 10a. The cooler housing 63 is connected to the housing main body 64 that defines the housing space S1 of the core 61, the downstream end of the bypass passage 80, the intake air that has passed through the bypass passage 80, and the intake air that has been cooled by the core 61. And a merging portion 65 where the merging points are provided.

  The housing body 64 is formed in a rectangular thin box shape that extends along the mounting surface 10a and has an opening on the front surface side and the rear surface side. The downstream end of the second passage 35 is connected to the opening portion 64a on the front surface side. On the other hand, the upstream end of the third passage 36 is connected to the opening 64b on the rear surface side. The housing body 64 also has an opening on the right side. The opening 64 c is configured as an insertion opening when the core 61 is accommodated in the housing main body 64, and is closed by the core connection portion 62. The housing space S1 of the core 61 is defined by the top wall portion 64d, the bottom wall portion 64e, the left side wall portion 64f, and the core connection portion 62 of the housing body 64. As will be described below, the bottom wall portion 64e and the left side wall portion 64f also partition the inner wall portion of the merge portion 65.

  Therefore, as indicated by an arrow A3 in FIGS. 8 to 9, the intake air that has passed through the second passage 35 flows into the housing body 64 from the front opening 64a and flows from the front side toward the rear side. Yes. In that case, it passes through the core 61 while being cooled by the cooling water supplied to the water tube. The cooled intake air flows out from the opening 64 b on the rear surface side of the housing body 64 and flows into the third passage 36.

  As shown in FIG. 5 to FIG. 6 and FIG. 8 to FIG. 9, the merging portion 65 includes an inlet portion 66 to which the downstream end of the bypass passage 80 is connected, and intake air flowing in from the inlet portion 66, 63, a communication portion 67 that leads to a space S2 on the downstream side (rear side) of the housing space S1 of the core 61 is provided. The junction 65 according to the present embodiment is made of resin.

  As shown in FIGS. 5 to 6 and the like, the inlet portion 66 is provided at the lower portion of the left side surface of the intercooler 60 and is configured as a tubular portion protruding leftward from the lower portion. The upstream end (left end) of the inlet 66 is open toward the left, and the downstream end of the bypass passage 80 is connected thereto.

  The communication part 67 extends along the outer surface of the left side wall part 64f of the housing body 64 and the outer surface of the bottom wall part 64e, and is a passage that communicates with the space S2 downstream of the core 61 in the intercooler 60. It is partitioned. Specifically, in the communication portion 67, the left side wall portion 64f extends outward (leftward) and communicates with the downstream end (right end) of the inlet portion 66 and the left portion of the space S2 behind the core 61. While the first communication part 67a is configured, the outer side (downward) of the bottom wall part 64e extends to the left and right and communicates with the lower end of the first communication part 67a and the bottom part of the space S2 behind the core 61. A second communication part 67b is configured. The first communication part 67a and the second communication part 67b guide the intake air flowing from the inlet part 66 to the space S2 behind the core 61. A part of the second communication portion 67b is formed so as to bulge downward as shown in the longitudinal section of FIG. By bulging in such a manner, it is possible to reduce the ventilation resistance when the intake air flows through the second communication portion 67b.

  Therefore, as indicated by an arrow A6 in FIG. 6, the intake air that has passed through the bypass passage 80 flows into the merging portion 65 through the inlet portion 66 and reaches the communication portion 67. The intake air reaching the communication portion 67 flows so as to wrap around the rear side of the core 61 along the outer surface of the left side wall portion 64f and the bottom wall portion 64e of the housing body 64, and then in the space S2 behind the core 61. It is designed to merge with the intake air that has passed through. For example, the intake air from the bypass passage 80 to the communication portion 67 flows downward along the first communication portion 67a and then flows to the right along the second communication portion 67b, thereby entering the space S2 behind the core 61. Inflow (refer to arrow A8 in FIGS. 6 and 9), or flow into the space S2 by flowing forward along the first communication portion 67a (see arrow A7 in FIG. 8). It is supposed to be.

  The bypass passage 80 is formed in a curved tube shape extending from the upper side to the lower side and then extending to the right side, and its upstream end (upper end) is constituted by a valve body 80a in which a bypass valve 81 is built. On the other hand, the downstream portion of the valve body 80a is constituted by a bypass passage body 80b formed as a curved pipe portion.

The valve body 80a is formed in a metal short cylinder shape, and as shown in FIGS.
Under the 1st channel | path 34, it arrange | positions with the attitude | position which orient | assigned the opening of both ends up and down, and is arrange | positioned so that it may be located ahead of the part near the left end of the attachment surface 10a. The branch end 34c of the first passage 34 is connected to the upstream end (upper end) of the valve body 80a, while the upstream end of the bypass passage body 80b is connected to the downstream end (lower end) of the valve body 80a. Yes.

  The bypass passage main body 80 b is configured to connect the branch portion 34 c of the first passage 34 to the joining portion 65 of the cooler housing 63. Specifically, the bypass passage main body 80b is made of a resin and is configured as an elbow-shaped curved pipe portion. The bypass passage main body 80b is located below the first passage 34 and the valve body 80a and on the left side of the intercooler 60. It is arranged in a posture with the opening facing. Similarly to the valve body 80a, the bypass passage main body 80b is arranged to be positioned in front of the portion near the left end of the mounting surface 10a. The downstream end (lower end) of the valve body 80a is connected to the upstream end (upper end) of the bypass passage body 80b, while the inlet 66 of the merging portion 65 is connected to the downstream end (right end) of the bypass passage body 80b. It is connected.

  Therefore, as shown by an arrow A6 in FIG. 6, the intake air branched from the first passage 34 and flowing into the bypass passage 80 passes through the bypass valve 81 built in the valve body 80a, and then flows into the bypass passage body 80b. To do. The air that has flowed into the bypass passage main body 80 b flows downward, then flows to the right, and flows into the junction 65 through the inlet 66.

  10 is a front view showing the third passage 36 and the distribution passage 70 as viewed from the front side, FIG. 11 is a cross-sectional view of the distribution passage 70, and FIG. 12 partially crosses the distribution passage 70. It is a perspective view shown.

  The third passage 36 is a resin member molded integrally with the distribution passage 70 and is configured to connect the intercooler 60 to the distribution passage 70 as shown in FIGS. 6 and 9. . Specifically, the third passage 36 is fastened to the cooler housing 63 in order from the upstream side, and a collecting portion 36a into which intake air that has passed through the intercooler 60 or the bypass passage 80 flows, and a distribution passage for collecting the intake air collected in the collecting portion 36a. And an introduction portion 36 b leading to 70. Further, as shown in FIGS. 10 to 12, a support portion 37 that is fastened to the central brackets 52 </ b> C and 52 </ b> C of the casing 52 is provided on the front surface near the boundary between the collecting portion 36 a and the introduction portion 36 b. The third passage 36 constitutes an “introduction passage” according to the present embodiment.

  The gathering portion 36a is formed in a box shape with the front and back sides, that is, the cooler housing 63 side opened, and the front and rear depths being shallow, and the open portion is an opening on the rear side of the housing main body 64 as shown in FIG. 64b. As shown in FIG. 9 and the like, the collective portion 36a is positioned between the rear surface of the housing main body 64 and the mounting surface 10a of the engine main body 10. Further, the upstream end of the introducing portion 36b is connected to the rear surface of the collecting portion 36a.

  The introduction portion 36b is formed as a curved pipe portion extending substantially in the vertical direction, and its upstream end is connected to the rear surface of the collecting portion 36a, while its downstream end is the lower surface central portion 71a of the surge tank 71 (FIG. 11). To FIG. 12). As shown in FIG. 9 and the like, the introduction portion 36b is formed to extend along a gap between a portion from the rear surface of the collecting portion 36a to the rear surface of the casing 52 and the mounting surface 10a of the engine body 10. Yes.

  More specifically, as shown in FIG. 10, the upstream portion of the introduction portion 36b (corresponding to the section P1 in FIG. 10) extends obliquely upward to the right from the connection portion with the assembly portion 36a, while being downstream of the introduction portion 36b. The portion (corresponding to the section P2 in FIG. 10) is formed to extend directly upward from the upper end of the upstream portion to the connection portion with the surge tank 71.

  As shown in FIG. 9 and the like, the support portion 37 is formed so that bolts can be inserted in the cylinder row direction, and is configured to support the inserted bolts from below. When the supercharger 50 is disposed at a predetermined mounting position, the central bracket 52C of the casing 52 sandwiches the support portion 37 from both sides in the cylinder row direction. In such a state, the casing 52 and the supercharger 50 are fastened to the third passage 36 by screwing one bolt into the bolt insertion port of the central bracket 52C and the support portion 37. It is like that. The supercharger 50 can be supported by the third passage 36 via the screwed bolts.

  As shown in FIGS. 4 to 6 and FIGS. 10 to 12, the distribution passage 70 is formed on the rear side of the surge tank 71 and the surge tank 71 extending in the cylinder row direction (left-right direction). And eight independent passages 72 connected to 16. As shown in FIG. 4 and the like, the distribution passage 70 is located between the supercharger 50 and the engine main body 10, and specifically, the rear surface of the casing 52, the mounting surface 10a of the engine main body 10, and the like. It is interposed between. Further, on the side surface (front surface) opposite to the engine body 10 in the surge tank 71, a right end side fastening portion 71R to which a right end side bracket 52R provided on the casing 52 of the supercharger 50 is fastened, and a left end side bracket 52L. Is provided with a left end side fastening portion 71L.

  The surge tank 71 extends in the cylinder row direction from the position of the intake port 16 corresponding to the first cylinder 18a to the position of the intake port 16 corresponding to the fourth cylinder 18d, and is closed at both ends in the same direction. It is formed in a bottomed cylindrical shape. Moreover, as shown in FIG. 12, the downstream end of the introduction part 36b is connected to the lower surface of the surge tank 71. Specifically, the downstream portion of the introduction portion 36 b is formed such that the extending direction of the downstream portion is orthogonal to the extending direction of the surge tank 71. Further, the downstream portion of the introduction portion 36b is connected to the central portion in the cylinder row direction on the lower surface of the surge tank 71. In the surge tank 71, a dimension D1 from the connection portion with the introduction portion 36b to one end in the cylinder row direction is set. The dimension D2 from the connecting portion to the other end in the cylinder row direction is equal to D2 (D1 = D2). With such a configuration, it is possible to ensure intake distribution performance, which is advantageous in reducing the difference in intake efficiency between cylinders.

  Eight independent passages 72 are formed on a side surface (rear surface) of the surge tank 71 on the engine body side. Each of the eight independent passages 72 is formed as a passage extending along the front-rear direction, and one end side communicates with the space in the surge tank 71, while the other end side is the engine body side (rear side). Is open. Each of the eight independent passages 72 is formed at a position corresponding to each of the eight intake ports 16. By fastening the distribution passage 70 to the cylinder block 11, the distribution passage 70 is connected to the intake port 16 via the intake port 16. It becomes possible to connect to each cylinder 18.

  Therefore, the intake air flowing into the third passage 36 from the intercooler 60 passes through the collecting portion 36a (see arrow A4 in FIG. 9), and then obliquely upwards right along the upstream portion (section P1) of the introduction portion 36b. And then flows directly upward along the downstream portion (section P2) of the introduction portion 36b. The intake air that has passed through the introduction part 36b flows into the cylinder center of the surge tank 71 in the cylinder row direction, is temporarily stored in the surge tank 71, and then supplied to each cylinder 18 from the independent passage 72 (FIG. 9). (See arrow A5).

  Here, the right end side fastening portion 71R and the left end side fastening portion 71L have bolt insertion portions that extend in the cylinder axial direction (vertical direction) and open upward as shown in FIGS. Have. When the supercharger 50 is disposed at the aforementioned mounting position, the right end side bracket 52R is placed on the right end side fastening portion 71R, while the left end side bracket 52L is placed on the left end side fastening portion 71L. It has become so. In such a state, a bolt is inserted and screwed into the bolt insertion port of the right end side bracket 52R and the bolt insertion portion of the right end side fastening portion 71R, while the bolt insertion port of the left end side bracket 52L and the left end The casing 52 and, consequently, the supercharger 50 are fastened to the distribution passage 70 by inserting another bolt into the bolt insertion portion of the side fastening portion 71L and screwing it. The supercharger 50 can be supported by the distribution passage 70 via the screwed bolts.

  In the intake passage 30 according to the present embodiment, the intake air purified by the air cleaner 31 flows into the first passage 34. Here, by opening or closing the bypass valve 81, it is possible to switch whether or not intake air flows through the bypass passage 80. The intake air that has flowed into the first passage 34 is guided from the first passage 34 to the supercharger 50 and is compressed in the supercharger 50 when the bypass valve 81 is closed. The compressed intake air is discharged to the second passage 35 and then cooled when passing through the core 61 of the intercooler 60 and then reaches the third passage 36. On the other hand, when the bypass valve 81 is open, the intake air bypasses the supercharger 50 and the core 61 by passing through the bypass passage 80 branched from the middle of the first passage 34. The intake air that has passed through the supercharger 50 or the like, or the intake air that has bypassed the supercharger 50 or the like passes through the space S2 behind the core 61, and is then guided to the distribution passage 70 via the third passage 36. It is distributed to each of the independent passages 72.

  Here, the intake air guided to the distribution passage 70 via the bypass passage 80 flows along a flow path curved in an arc shape. Specifically, when the intake passage 30 is viewed from the front along the direction along the intake / exhaust direction (FIG. 6 illustrates the intake passage 30 viewed from the exhaust side as a front view), The central axis of the flow path formed by the portion extending to the passage 36 is curved so as to protrude obliquely downward as indicated by arrows A6 and A4 in FIG. Such a flow path is effective in reducing the ventilation resistance of the intake air.

  Here, when returning to the overall configuration of the intake passage 30, as shown in FIGS. 4 to 6, the supercharger 50 and the intercooler 60 are located on the side (front) of the mounting surface 10 a from above. They are arranged in order. The branch portion 34c is arranged on one side (left side) in the cylinder row direction with respect to the supercharger 50 on the side (front) of the mounting surface 10a. On the other hand, the merging portion 65 is disposed on the outer surface (the left side surface in FIG. 6) of the cooler housing 63 on the side of the branching portion 34 c, and the downstream portion (specifically, the core 61 in the cooler housing 63. Communicates with the space S2).

  According to such a configuration, since the supercharger 50 and the intercooler 60 are both disposed on the side of the mounting surface 10a, the bypass passage 80 can be provided along the same side surface 10a. . This is effective in laying out the bypass passage 80 in a compact manner.

  In addition, the branch portion 34 c is disposed on one side in the cylinder row direction with respect to the supercharger 50. On the other hand, an intercooler 60 is disposed below the supercharger 50, and the merging portion 65 is disposed on the outer surface of the cooler housing 63 on the branching portion 34 c side. Therefore, the bypass passage 80 extends along the attachment surface 10a in a space on one side in the cylinder row direction with respect to the supercharger 50. That is, the bypass passage 80 is monotonically extended from the upper side to the lower side along the mounting surface 10a starting from the branch portion 34c, and then connected to the branch portion 34c provided on the outer surface of the cooler housing 63. . In this way, the configuration in which the bypass passage 80 is connected to the outer surface on the side of the branching portion 34c without turning around the cooler housing 63 from the lower side, the side, and the upper side, in particular, the bypass passage 80 is connected to the distribution passage 70. Compared with a configuration in which the bypass passage 80 is directly connected, the bypass passage 80 is effective in a compact layout.

  Further, such a configuration is effective in preventing the bypass passage 80 from protruding from the upper end of the engine body 10 and thus making the entire engine compact in the height direction.

  In general, the third passage 36 connecting the intercooler 60 and the distribution passage 70 in the intake passage 30 is configured in consideration of the distribution performance of the intake air. Since the merging portion 65 communicates with the downstream portion S2 of the cooler housing 63 relative to the core 61, the intake air that has passed through the bypass passage 80 passes through the passage 36 configured in consideration of the distribution performance. Then, it flows into the distribution passage 70. As a result, it is possible to suppress the difference between the cylinders in the intake efficiency due to the intake air that has passed through the bypass passage 80.

  Therefore, according to the above configuration, the bypass passage 80 can be laid out in a compact manner while suppressing the difference in intake efficiency between the cylinders.

  Further, as shown by the arrangement positions of the first communication portion 67a and the second communication portion 67b, the merging portion 65 has an outer surface on the anti-supercharger 50 side from the outer surface on the branching portion 34c side in the cooler housing 63 (FIG. 6). Specifically, it extends over the outer surface on the side opposite to the supercharger 50.

  For example, when the merger 65 is provided on the upper surface of the cooler housing 63, it is necessary to vertically separate the intercooler 60 and the supercharger 50 as much as a space for providing the merger 65 is secured. This is inconvenient when the engine 1 is made compact in the height direction.

  On the other hand, as described above, by providing the merging portion 65 from the outer surface on the branching portion 34c side to the outer surface on the anti-supercharger 50 side, it is advantageous in bringing the intercooler 60 and the supercharger 50 closer to each other vertically. As a result, it is advantageous to make the engine 1 compact in the height direction.

  The third passage 36, which is a portion of the intake passage 30 that connects the intercooler 60 to the distribution passage 70, is interposed between the intercooler 60 and the engine body 10.

  Thus, since the third passage 36 is provided in the gap between the intercooler 60 and the engine body 10, it is advantageous to make the intake passage 30 and thus the entire engine compact.

  Furthermore, since the third passage 36 is connected to the central portion of the distribution passage 70 in the cylinder row direction, the intake air that has passed through the third passage 36, that is, the turbocharger 50 that has just passed through the core 61 is supercharged. Therefore, it is possible to reduce the difference in intake efficiency between the cylinders due to the intake air that has passed through or through the bypass passage 80.

  Further, when the intake passage 30 is viewed from the front along the intake / exhaust direction, the central axis of the flow path formed by the portion from the bypass passage 80 to the third passage 36 protrudes downward. Therefore, it is advantageous in reducing the airflow resistance of the intake air that bypasses the supercharger 50.

<< Other embodiments >>
About the said embodiment, it is good also as following structures.

  In the above-described embodiment, the engine 1 is configured as a 4-cylinder horizontal engine, but is not limited thereto, and may be configured as a 3-cylinder engine or an engine having 5 or more cylinders. Further, the engine 1 may be configured as a vertical engine. In that case, the intake passage 30 and the fuel pump 96 are arranged along one of the left and right side surfaces of the engine body 10.

  Moreover, in the said embodiment, although the supercharger 50 was comprised as a mechanical drive supercharger, you may comprise as an electric supercharger not only this.

  Moreover, in the said embodiment, although the bypass channel | path main body 80b was comprised as an elbow-shaped curved pipe part, it is not restricted to this, For example, it is extended from left to right as it goes downward from the upper part. You may comprise as a straight pipe part arrange | positioned in.

1 Engine 10 with a turbocharger Engine body 10a Mounting surface (side surface on the intake side)
16 Intake port 18 Cylinder 30 Intake passage 34c Branch portion 36 Third passage (introduction passage)
50 Supercharger 60 Intercooler 61 Core 63 Cooler housing 65 Merging portion 70 Distribution passage 80 Bypass passage

Claims (6)

An engine body having a plurality of cylinders;
An intake passage disposed outside the engine body and connected to each of the plurality of cylinders via an intake port,
The intake passage is provided with a supercharger and an intercooler disposed downstream of the supercharger in the direction of intake air flow,
In the engine with a supercharger, wherein the intercooler includes a core and a cooler housing that houses the core.
The supercharger is arranged on the side of the intake side that is the side of the engine body where the upstream end of the intake port is open, while the intercooler is Arranged in the lower direction,
The supercharger and the intercooler are arranged so that at least a part of each overlaps with each other when the engine body is viewed from above.
A distribution passage configured to distribute the intake air that has passed through the intercooler to each of the plurality of cylinders is further provided in a portion downstream of the intercooler in the intake passage.
The intake passage also includes a branch portion disposed in a portion upstream of the supercharger in the intake passage, and a merging portion disposed between the core and the distribution passage in the intake passage. A bypass passage configured to connect to the section is provided,
The branching portion is disposed on one side of the cylinder row direction with respect to the supercharger on the side of the side surface on the intake side,
The supercharger-equipped engine is disposed on the outer surface of the cooler housing on the branching portion side and communicates with a downstream portion of the cooler housing from the core. The supercharged engine according to claim 1,
The supercharger-equipped engine, wherein the merging portion extends from an outer surface on the branching portion side of the cooler housing to an outer surface opposite to the supercharger. The engine with a supercharger according to claim 1 or 2,
The upstream end of the intake port is opened side by side along the cylinder row direction on the side surface on the intake side,
The engine with a supercharger that extends in the cylinder row direction so that the distribution passage covers the upstream end of the intake port. The engine with a supercharger according to claim 3,
The intercooler is attached to the side surface on the intake side at a predetermined interval,
An engine with a supercharger, wherein an introduction passage, which is a portion connecting the intercooler to the distribution passage in the intake passage, is interposed between the intercooler and the engine body. The engine with a supercharger according to claim 4,
The turbocharged engine, wherein the introduction passage is connected to a central portion of the distribution passage in the cylinder row direction. The engine with a supercharger according to claim 4 or 5, wherein when the intake passage is viewed from the front along a direction along the intake and exhaust directions, a flow path formed by a portion extending from the bypass passage to the introduction passage. An engine with a supercharger whose center axis is curved so as to protrude downward.

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