JP2018173013A - Intake device for multiple cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evenly distribute gas to each of cylinders while compactly laying out an intake passage in an intake device for a multiple cylinder engine.SOLUTION: An intake passage 30 includes: a plurality of independent passages 39 connected with each of intake ports 17, 18; a surge tank 38 to which an upstream side end of the independent passage 39 is connected; first and second branch passages 46R, 46L having lower ends connected with the surge tank 38; and upstream side common passages 43-45 having a downstream side end from which the first and the second branch passages 46R, 46L are branched. The upstream side common passages 43-45 include a first passage 43 which extends in a direction from one side to the other side of a cylinder row direction, a second passage 44 which is bent to direct in a direction of the surge tank after extending to separate from the surge tank 38, and a third passage 45 from which the first and the second branch passages 46R, 46L are branched after extending along the direction of the surge tank, in order from the upstream side.SELECTED DRAWING: Figure 12

Description

  The technology disclosed herein relates to an intake device for a multi-cylinder engine.

  In Patent Document 1, as an example of an intake device of a multi-cylinder engine, an intake device (intake manifold) for an in-line three-cylinder engine having three cylinders arranged in a row and two intake ports for each cylinder. ) Is disclosed. In this intake device, a total of six independent passages (distribution pipes) connected to two of each of the three cylinders, and upstream ends of the six independent passages are arranged in the order in which the corresponding cylinders are arranged. A surge tank (collection pipe) connected side by side, and two branch passages (branch pipes) each having a downstream end connected to the surge tank and introducing gas into the surge tank. It is configured. The two branch passages are branched from one common passage and constitute a so-called tournament type intake passage.

  This Patent Document 1 also discloses that two branch passages are connected at an interval in the cylinder row direction. Specifically, the intake device disclosed in Patent Document 1 connects one of the two branch passages to a portion facing a section from the first cylinder to the second cylinder and two upstream sides. The other of the passages is connected to a portion facing the section from the second cylinder to the third cylinder. This connection is advantageous in introducing fresh air evenly to each cylinder.

Japanese Patent Laid-Open No. 10-068361

  By the way, when the tournament type intake passage as described in Patent Document 1 is used, the portion corresponding to the shared passage before branching is arranged in the cylinder row direction so as to be along the outer surface of the engine for the sake of layout. It is conceivable to extend in a direction from one side to the other side (for example, a direction from the rear side to the front side of the engine). The shared passage extended in this way is branched into a plurality of branch passages immediately after being bent toward the surge tank, and each branch is connected to the surge tank at intervals in the cylinder row direction. Will be.

  However, in the case of such a configuration, there is a possibility that the gas introduction amount may vary between the branch passage connected to one side in the cylinder row direction and the branch passage connected to the other side. Noticed.

  That is, the gas flowing through the intake passage is directed in a direction from one side to the other side in the cylinder row direction when passing through the shared passage. Then, among the plurality of branch passages, the gas is relatively easy to flow with respect to the branch passage located on the other side in the cylinder row direction (for example, the front side of the engine), while the one side in the cylinder row direction ( For example, regarding the branch passage located on the rear side of the engine, the gas is less likely to flow. Such a situation is undesirable for evenly distributing gas to each cylinder.

  Therefore, the shared passage bent toward the surge tank is not branched immediately after being bent, but once in a direction perpendicular to the cylinder row direction and toward the surge tank (hereinafter also referred to as “surge tank direction”). After extending straight along, it is possible to branch into a plurality of branch passages. In this case, the gas flowing through the shared passage flows along the wall surface defining the portion extending in the surge tank direction, thereby reducing directivity from one side to the other side in the cylinder row direction, and the surge tank direction. To become oriented. As a result, gas can be evenly distributed to each branch passage and thus to each cylinder on one side and the other side in the cylinder row direction.

  Thus, in order to equalize the gas flowing through each branch passage, it is required to flow the gas along the wall surface of the portion extending in the surge tank direction. In that respect, simply installing a portion extending in the surge tank direction does not necessarily satisfy such a requirement, and there is room for improvement.

  In the first place, if a part extending in the direction of the surge tank is newly installed, the shared passage will be separated from the surge tank according to the size of the part, which may cause trouble in laying out the intake passage in a compact manner. . On the other hand, in order to reliably reduce the directivity of the gas, it is required to extend the portion extending in such a direction as long as possible.

  The technology disclosed herein has been made in view of the above points, and the object of the technology is to provide a uniform layout of the intake passage in a multi-cylinder engine intake device and to distribute gas evenly to each cylinder. To distribute to.

  The technology disclosed herein includes a plurality of at least three or more cylinders arranged in a row, a plurality of intake ports communicating with each of the plurality of cylinders, and an intake air connected to each of the plurality of intake ports. A multi-cylinder engine including a passage.

  The intake passage includes a plurality of downstream independent passages connected to each of the plurality of intake ports, and upstream ends of the plurality of downstream independent passages arranged in a line according to the order in which the corresponding cylinders are arranged. The surge tanks connected side by side, each downstream end portion connected to the surge tank, a plurality of upstream independent passages for introducing gas into the surge tank, and the plurality of upstream independent passages branch from the downstream end portions And an upstream shared passage.

  The downstream end portions of the plurality of upstream independent passages extend in a surge tank direction perpendicular to the cylinder row direction and indicate a direction toward the surge tank, and the plurality of downstream independent passages in the surge tank. Are connected to portions facing the respective upstream end portions.

  The upstream shared passage is continuous from the upstream side in order from the first passage portion extending in the direction from one side to the other side in the cylinder row direction, and the downstream end portion of the first passage portion, After extending away from the surge tank, when viewed in the cylinder axial direction, the second passage portion is bent so as to be directed in the surge tank direction, and is connected to the downstream end portion of the second passage portion. And a third passage portion where the plurality of upstream independent passages branch from the downstream end portion after extending along the tank direction.

  According to this configuration, the gas flowing through the intake passage is directed in the direction from one side to the other side in the cylinder row direction when passing through the first passage portion. Here, the gas flowing into the second passage portion from the first passage portion is guided in a direction away from the surge tank. At least a part of the gas thus guided flows along the wall surface on the side away from the surge tank among the wall surfaces defining the second passage portion.

  And since the 3rd channel | path part is extended in the surge tank direction before branching, when considering that the 2nd channel | path part and the 3rd channel | path part are continuing, it is 3rd from a 2nd channel | path part. Of the gas flowing into the passage portion, the gas flowing along the wall surface of the second passage portion is guided as it flows along the wall surface of the portion extending in the surge tank direction. As a result, the directivity from one side to the other side in the cylinder row direction can be reduced and the direction can be directed in the surge tank direction. As a result, the gas can be evenly distributed to the upstream independent passages as the branch passages, and to the respective cylinders.

  Moreover, according to the said structure, it becomes possible to extend a 3rd channel | path part long in a surge tank direction by the part which extended the 2nd channel | path part so that it might space apart from a surge tank. This is effective in directing the gas toward the surge tank. In addition, with respect to the first passage portion, for example, it is possible to maintain an arrangement along the outer surface of the engine. Therefore, the intake passage can be laid out more compactly compared with a configuration in which a portion extending in the surge tank direction is simply provided.

  Therefore, the gas can be evenly distributed to each cylinder while the intake passage is laid out in a compact layout.

  Further, a portion of the second passage portion that is bent so as to be directed in the surge tank direction has the other side in the cylinder row direction than a portion of the third passage portion that extends along the surge tank direction. It is good also as the bulging part which bulged to the side is formed.

  According to this configuration, at least a part of the gas flowing into the second passage portion from the first passage portion is guided in a direction away from the surge tank as described above, and then defines the second passage portion. It flows along the wall surface on the side away from the surge tank among the wall surfaces. The gas flowing along such a wall surface once passes through the bulging portion before flowing into the third passage portion from the second passage portion.

  As a result of intensive studies by the inventors of the present application, according to the obtained knowledge, the directivity due to the gas being guided away from the surge tank can be reduced by passing the bulging portion.

  The multi-cylinder engine connects an exhaust passage through which burned gas discharged from each of the cylinders flows, the exhaust passage and the intake passage, and a part of the burned gas is recirculated to the intake passage. An EGR passage to be provided, and a downstream end portion of the EGR passage may be connected to an upstream side of at least an upstream end portion of the second passage portion in the intake passage.

  According to this configuration, the burned gas flowing into the intake passage from the EGR passage is similar to other gases such as fresh air by connecting the downstream end portion of the EGR passage to at least the upstream side of the second passage portion. In addition, the second passage portion is passed. As a result, the burned gas is also guided in a direction away from the surge tank, so that it can be evenly distributed to each cylinder.

  The multi-cylinder engine includes a supercharger disposed on the opposite side of the plurality of cylinders with the surge tank interposed therebetween, and the intake passage is located on the upstream side of the surge tank. A supercharging passage provided with a machine, and a plurality of upstream independent passages and the upstream shared passage, and is branched into a bypass passage that bypasses the supercharger, and is downstream of the EGR passage. The portion may be connected to the vicinity of the branch portion in the intake passage.

  According to this configuration, the burned gas can be introduced into both the supercharging passage and the bypass passage. In addition, for example, the EGR passage can be laid out more compactly compared to a configuration in which the downstream end portion of the EGR passage is spaced upstream from the branch portion.

  The multi-cylinder engine includes a supercharger disposed on the opposite side of the plurality of cylinders with the surge tank interposed therebetween, and the intake passage includes a supercharge passage provided with the supercharger And a bypass passage that includes the plurality of upstream independent passages and the upstream shared passage, and bypasses the supercharger, and the bypass passage, when viewed in the cylinder axial direction, It is good also as arrange | positioning above a supercharger.

  According to this configuration, the bypass passage is made of, for example, resin, so that when the vehicle on which the multi-cylinder engine is mounted has a front collision, the bypass passage is not directly collided with the collision target and the supercharger. It can be used as a cushion.

  Further, the supercharging passage extends in the vertical direction in a vehicle-mounted state, and then is connected to the surge tank via an introduction port opened at a central portion in the cylinder row direction of the surge tank. Good.

  According to this configuration, with regard to the bypass passage, priority is given to the gas distribution performance as described above, while regarding the supercharging passage, a simpler layout than the bypass passage can be realized.

  As described above, according to the above-described intake device for a multi-cylinder engine, gas can be evenly distributed to each cylinder while the intake passage is laid out in a compact layout.

FIG. 1 is a schematic view illustrating the configuration of a multi-cylinder engine. FIG. 2 is a perspective view showing the multi-cylinder engine with a part thereof omitted. FIG. 3 is a plan view schematically showing a configuration around four cylinders. FIG. 4 is a perspective view showing the overall configuration of the intake device as viewed from the front side. FIG. 5 is a perspective view showing the overall configuration of the intake device as seen from the rear side. FIG. 6 is a cross-sectional view showing a passage structure on the supercharger side. FIG. 7 is a longitudinal sectional view showing a passage structure on the supercharger side. FIG. 8 is a perspective view showing a longitudinal section around the surge tank. FIG. 9 is a perspective view showing a vertical section different from FIG. FIG. 10 is a view showing a passage structure related to the bypass passage as seen from the front side. FIG. 11 is a view showing the passage structure according to the bypass passage as seen from the rear side. FIG. 12 is a view showing a passage structure related to the bypass passage as viewed from above. FIG. 13 is a partially enlarged view of the bypass passage. FIG. 14 is a longitudinal sectional view showing a connection structure between the surge tank and the bypass passage. FIG. 15 is a cross-sectional view showing a connection structure between the surge tank and the bypass passage. FIG. 16 is a view corresponding to FIG. 12 showing a conventional bypass passage.

  Hereinafter, an embodiment of an intake device of a multi-cylinder engine will be described in detail based on the drawings. In addition, the following description is an illustration. FIG. 1 is a diagram illustrating an engine 1 configured to include an intake device for a multi-cylinder engine disclosed herein. FIG. 2 is a perspective view in which the configuration is partially omitted, and FIG. 3 is a plan view schematically showing the configuration around the four cylinders 11.

  The engine 1 is a gasoline engine (particularly a 4-stroke internal combustion engine) mounted on an FF vehicle, and includes a mechanically driven supercharger (so-called supercharger) 34 as shown in FIG. It is configured.

  Further, as shown in FIG. 3, the engine 1 according to the present embodiment includes four cylinders (cylinders) 11 arranged in a row, and the four cylinders 11 are arranged along the vehicle width direction. It is configured as a so-called in-line 4-cylinder horizontal engine mounted in a posture. Thus, in the present embodiment, the engine longitudinal direction, which is the arrangement direction (cylinder row direction) of the four cylinders 11, substantially matches the vehicle width direction, and the engine width direction substantially matches the vehicle longitudinal direction. .

  Hereinafter, unless otherwise specified, the front side is one side in the engine width direction (the front side in the vehicle front-rear direction), the rear side is the other side in the engine width direction (the rear side in the vehicle front-rear direction), and the left side is the engine front-rear direction Direction (cylinder row direction) on one side (left side in the vehicle width direction and engine front side), and the right side is the other side in the engine longitudinal direction (cylinder row direction) (right side in the vehicle width direction and engine) Points to the rear).

  In the following description, the upper side refers to the upper side in a state where the engine 1 is mounted on the vehicle (hereinafter also referred to as “vehicle mounted state”), and the lower side refers to the lower side in the vehicle mounted state.

(Schematic configuration of the engine)
The engine 1 is configured as a front intake rear exhaust type. That is, the engine 1 is arranged on the front side of the engine body 10 having four cylinders 11 (only one cylinder is shown in FIG. 1) and the intake ports 17 and 18 as shown in FIG. And an exhaust passage 50 disposed on the rear side of the engine body 10 and communicating with each cylinder 11 via the exhaust port 19.

  The intake passage 30 according to the present embodiment includes a plurality of passages that guide gas, devices such as a supercharger 34 and an intercooler 36, and a bypass passage 40 that bypasses these devices in a unitized intake air. Configure the device.

  The engine main body 10 is configured to burn the mixture of gas and fuel supplied from the intake passage 30 in each cylinder 11 according to a predetermined combustion order. Specifically, the engine main body 10 includes a cylinder block 12 and a cylinder head 13 placed thereon.

  Four cylinders 11 are formed inside the cylinder block 12. The four cylinders 11 are arranged in a row along the central axis direction of the crankshaft 15 (that is, the cylinder row direction). The four cylinders 11 are each formed in a cylindrical shape, and the central axes (hereinafter referred to as “cylinder axes”) of the cylinders 11 extend parallel to each other and perpendicular to the cylinder row direction. Hereinafter, the four cylinders 11 shown in FIG. 3 may be referred to as the first cylinder 11A, the second cylinder 11B, the third cylinder 11C, and the fourth cylinder 11D in order from the right side along the cylinder row direction.

  A piston 14 is slidably inserted into each cylinder 11. The piston 14 is connected to the crankshaft 15 via a connecting rod 141. The piston 14 divides the combustion chamber 16 together with the cylinder 11 and the cylinder head 13.

  The ceiling surface of the combustion chamber 16 has a so-called pent roof shape and is constituted by the lower surface of the cylinder head 13. This engine 1 is configured such that the ceiling surface of the combustion chamber 16 is lower than before in order to increase the geometric compression ratio. The pent roof shape of the ceiling surface is close to a flat shape.

  Two intake ports 17 and 18 are formed in the cylinder head 13 for each cylinder 11. The two intake ports 17, 18 communicate with the combustion chamber 16, and each cylinder 11 has a first port 17 and a second port 18 adjacent to the first port 17 in the cylinder row direction. Have. In any of the first cylinder 11A to the fourth cylinder 11D, the first port 17 and the second port 18 are arranged in the same order. Specifically, as shown in FIG. 3, in each cylinder 11, the second port 18 and the first port 17 are arranged in order from the right side along the cylinder row direction.

  The upstream ends of the intake ports 17 and 18 open to the outer surface (mounting surface) 10 a of the engine body 10, respectively, and the downstream ends of the intake passages 30 are connected. On the other hand, the downstream ends of the ports 17 and 18 are respectively open to the ceiling surface of the combustion chamber 16.

  Hereinafter, in some drawings, “17A” is attached to the first port leading to the first cylinder 11A instead of “17”, and “18” is not attached to the second port leading to the cylinder 11A. “18A” may be attached. The same applies to the second cylinder 11B to the fourth cylinder 11D. For example, “18C” may be attached to the second port leading to the third cylinder 11C instead of “18”.

  Further, the two intake ports 17 and 18 include SCV ports configured so that the flow rate of the gas passing through each cylinder 11 is throttled through a swirl control valve (SCV) 80. In the present embodiment, the aforementioned second port 18 is configured as an SCV port.

  An intake valve 21 is disposed in each of the two intake ports 17 and 18. The intake valve 21 opens and closes between the combustion chamber 16 and each of the intake ports 17 and 18. The intake valve 21 is opened and closed at a predetermined timing by an intake valve mechanism.

  In this configuration example, the intake valve mechanism has an intake electric VVT (Variable Valve Timing) 23 which is a variable valve mechanism as shown in FIG. The intake electric VVT 23 is configured to continuously change the rotation phase of the intake camshaft within a predetermined angle range. Thereby, the valve opening timing and the valve closing timing of the intake valve 21 change continuously. The intake valve mechanism may have a hydraulic VVT instead of the electric VVT.

  The cylinder head 13 is also formed with two exhaust ports 19, 19 for each cylinder 11. The two exhaust ports 19, 19 communicate with the combustion chamber 16.

  Exhaust valves 22 are disposed in the two exhaust ports 19, 19, respectively. The exhaust valve 22 opens and closes between the combustion chamber 16 and the exhaust ports 19 and 19. The exhaust valve 22 is opened and closed at a predetermined timing by an exhaust valve mechanism.

  In this configuration example, the exhaust valve mechanism has an exhaust electric VVT (Variable Valve Timing) 24 that is a variable valve mechanism as shown in FIG. The exhaust electric VVT 24 is configured to continuously change the rotation phase of the exhaust camshaft within a predetermined angle range. Thereby, the valve opening timing and the valve closing timing of the exhaust valve 22 continuously change. The exhaust valve mechanism may have a hydraulic VVT instead of the electric VVT.

  Although details are omitted, the engine 1 adjusts the length of the overlap period related to the opening timing of the intake valve 21 and the closing timing of the exhaust valve 22 by the intake electric VVT 23 and the exhaust electric VVT 24. As a result, residual gas in the combustion chamber 16 is scavenged, hot burned gas is confined in the combustion chamber 16 (that is, internal EGR (Exhaust Gas Recirculation) gas is introduced into the combustion chamber 16). ) In this configuration example, the intake electric VVT 23 and the exhaust electric VVT 24 constitute an internal EGR system. Note that the internal EGR system is not necessarily configured by VVT.

  An injector 6 is attached to the cylinder head 13 for each cylinder 11. In this configuration example, the injector 6 is a multi-injection type fuel injection valve, and is configured to inject fuel directly into the combustion chamber 16.

  A fuel supply system 61 is connected to the injector 6. The fuel supply system 61 includes a fuel tank 63 configured to store fuel, and a fuel supply path 62 that connects the fuel tank 63 and the injector 6 to each other. A fuel pump 65 and a common rail 64 are interposed in the fuel supply path 62. The fuel pump 65 pumps fuel to the common rail 64. In this configuration example, the fuel pump 65 is a plunger-type pump driven by the crankshaft 15. The common rail 64 is configured to store the fuel pumped from the fuel pump 65 at a high fuel pressure. When the injector 6 is opened, the fuel stored in the common rail 64 is injected into the combustion chamber 16 from the injection port of the injector 6.

  A spark plug 25 is attached to the cylinder head 13 for each cylinder 11. The spark plug 25 is attached in such a posture that its tip faces the combustion chamber 16 and forcibly ignites the air-fuel mixture in the combustion chamber 16.

  As shown in FIG. 2, the intake passage 30 is connected to a front side surface (hereinafter referred to as “mounting surface”) 10 a in the engine body 10 and communicates with the intake ports 17 and 18 of each cylinder 11. The intake passage 30 is a passage through which gas introduced into the combustion chamber 16 flows. An air cleaner 31 that filters fresh air is disposed at the upstream end of the intake passage 30. A surge tank 38 is disposed near the downstream end of the intake passage 30. As shown in FIG. 3, the intake passage 30 downstream of the surge tank 38 constitutes an independent passage 39 that branches into two for each cylinder 11.

  Although details will be described later, one of the two independent passages 39 is connected to the first port 17 and the other is connected to the second port 18. Hereinafter, the former independent passage 39 may be denoted by reference numeral “391” while the latter may be denoted by reference numeral “392”. In this way, the downstream end of the independent passage 39 is connected to the intake ports 17 and 18 of each cylinder 11. The independent passage 39 is an example of a “downstream independent passage”.

  A throttle valve 32 is disposed between the air cleaner 31 and the surge tank 38 in the intake passage 30. The throttle valve 32 is configured to adjust the amount of fresh air introduced into the combustion chamber 16 by adjusting the opening thereof.

  A supercharger 34 is also disposed in the intake passage 30 downstream of the throttle valve 32. The supercharger 34 is configured to supercharge the gas introduced into the combustion chamber 16. In this configuration example, the supercharger 34 is a mechanical supercharger driven by the engine 1. Although the supercharger 34 according to the present embodiment is configured as a roots-type supercharger, this configuration may be anything. For example, a re-sholm type or a centrifugal type may be used.

  An electromagnetic clutch 34 a is interposed between the supercharger 34 and the engine 1. The electromagnetic clutch 34a transmits driving force between the supercharger 34 and the engine 1 or interrupts transmission of driving force. An unillustrated control means such as an ECU (Engine Control Unit) switches between disconnection and connection of the electromagnetic clutch 34a, whereby the supercharger 34 is switched on and off. That is, the engine 1 switches between an operation of supercharging the gas introduced into the combustion chamber 16 and an operation of not supercharging the gas introduced into the combustion chamber 16 by switching the supercharger 34 on and off. It is configured to be able to.

  An intercooler 36 is disposed downstream of the supercharger 34 in the intake passage 30. The intercooler 36 is configured to cool the gas compressed in the supercharger 34. The intercooler 36 in this configuration example is configured as a water-cooled type.

  Further, as a passage connecting various devices incorporated in the intake passage 30, the intake passage 30 is disposed downstream of the air cleaner 31, and a first passage that guides the intake air purified by the air cleaner 31 to the supercharger 34. 33, a second passage 35 that guides the intake air compressed by the supercharger 34 to the intercooler 36, and a third passage 37 that guides the gas cooled by the intercooler 36 to the surge tank 38. The surge tank 38 is disposed in the vicinity of the inlet (upstream end) of the intake ports 17 and 18 in order to shorten the flow path length (runner length) from the surge tank 38 to the intake ports 17 and 18. The second passage 35 and the third passage 37 together with the supercharger 34 and the intercooler 36 constitute a “supercharging passage”.

  The intake passage 30 is provided with a bypass passage 40 that bypasses the supercharger 34 and the intercooler 36. The bypass passage 40 connects the portion of the intake passage 30 from the downstream portion of the throttle valve 32 to the upstream portion of the supercharger 34 and the surge tank 38. The bypass passage 40 is provided with a bypass valve 41 configured to adjust the flow rate of the gas flowing through the bypass passage 40.

  When the supercharger 34 is turned off (that is, when the electromagnetic clutch 34a is disconnected), the bypass valve 41 is fully opened. As a result, the gas flowing through the intake passage 30 bypasses the supercharger 34 and flows into the surge tank 38 and is introduced into the combustion chamber 16 via the independent passage 39. The engine 1 is operated in a non-supercharged state, that is, in a natural intake state.

  When the supercharger 34 is turned on (that is, when the electromagnetic clutch 34a is connected), the opening degree of the bypass valve 41 is appropriately adjusted. As a result, part of the gas that has passed through the supercharger 34 in the intake passage 30 flows back upstream of the supercharger 34 through the bypass passage 40. Since the reverse flow rate can be adjusted by adjusting the opening degree of the bypass valve 41, the supercharging pressure of the gas introduced into the combustion chamber 16 can be adjusted. In this configuration example, the supercharger 34, the bypass passage 40, and the bypass valve 41 constitute a supercharging system.

  The exhaust passage 50 is connected to the rear side surface of the engine body 10 and communicates with the exhaust port 19 of each cylinder 11. The exhaust passage 50 is a passage through which exhaust gas discharged from the combustion chamber 16 flows. Although the detailed illustration is omitted, the upstream portion of the exhaust passage 50 constitutes an independent passage branched for each cylinder 11. The upstream end of the independent passage is connected to the exhaust port 19 of each cylinder 11. An exhaust gas purification system having one or more catalytic converters 51 is disposed in the exhaust passage 50. The catalytic converter 51 includes a three-way catalyst. Note that the exhaust gas purification system is not limited to one including only a three-way catalyst.

  An EGR passage 52 constituting an external EGR system is connected between the intake passage 30 and the exhaust passage 50. The EGR passage 52 is a passage for returning a part of the burned gas to the intake passage 30. The upstream end of the EGR passage 52 is connected downstream of the catalytic converter 51 in the exhaust passage 50. The downstream end of the EGR passage 52 is connected upstream of the supercharger 34 in the intake passage 30 and upstream of the upstream end of the bypass passage 40.

  A water-cooled EGR cooler 53 is disposed in the EGR passage 52. The EGR cooler 53 is configured to cool the burned gas. An EGR valve 54 is also disposed in the EGR passage 52. The EGR valve 54 is configured to adjust the flow rate of burned gas flowing through the EGR passage 52. By adjusting the opening degree of the EGR valve 54, the recirculation amount of the cooled burned gas, that is, the external EGR gas can be adjusted.

  In this configuration example, the EGR system 55 includes an external EGR system that includes an EGR passage 52 and an EGR valve 54, and an internal EGR system that includes the above-described intake electric VVT 23 and exhaust electric VVT 24. It is configured.

(Configuration of intake passage)
Hereinafter, the configuration of the intake passage 30 will be described in detail.

  4 is a perspective view showing the entire configuration of the unitized intake passage 30 as seen from the front side, and FIG. 5 is a perspective view showing the overall configuration of the intake passage 30 as seen from the rear side. FIG. 6 is a transverse sectional view showing a supercharger side passage structure in the intake passage 30, and FIG. 7 is a longitudinal sectional view thereof. FIG. 8 is a perspective view showing a vertical section around the surge tank 38, and FIG. 9 is a perspective view showing another vertical section.

  Each part constituting the intake passage 30 is arranged on the front side of the engine body 10, specifically, in front of the mounting surface 10a. Note that the mounting surface 10a is configured by a front outer surface of the cylinder head 13 and the cylinder block 12, as shown in FIGS.

  First, a schematic arrangement of each part constituting the intake passage 30 will be described.

  As shown in FIG. 2 and FIGS. 4 to 8, the supercharger 34 is disposed opposite to the four cylinders 11 across the surge tank 38. A gap (interval) corresponding to the dimension of the surge tank 38 is provided between the rear surface of the supercharger 34 and the mounting surface 10a. The first passage 33 extends along the cylinder row direction on the left side of the supercharger 34 and is connected to the left end of the supercharger 34. Further, the intercooler 36 is disposed below the supercharger 34, and is disposed at a predetermined interval with respect to the mounting surface 10 a, similarly to the supercharger 34. The supercharger 34 and the intercooler 36 are adjacent to each other in the vertical direction. The second passage 35 extends vertically so as to connect the front part of the supercharger 34 and the front part of the intercooler 36. The surge tank 38 is disposed in a gap between the supercharger 34 and the mounting surface 10a, and sandwiches a plurality of independent passages 39 with respect to the end portions (inlet) of the intake ports 17 and 18 on the non-cylinder side. Opposed to the opposite side. The third passage 37 is extended so as to sew a gap between the intercooler 36 and the supercharger 34 and the mounting surface 10a, so that the intercooler 36 is positioned below the surge tank 38. The rear part of the intercooler 36 and the bottom part of the surge tank 38 are connected. The bypass passage 40 is formed so as to extend upward from the middle of the first passage 33 and then extend inward (rightward) of the engine body 10 and is connected to the upper portion of the surge tank 38. Yes.

  Next, the structure of each part constituting the intake passage 30 will be described.

  The first passage 33 is formed in a tubular shape extending substantially in the cylinder row direction (left-right direction), and an upstream side (left side) portion thereof is constituted by a throttle body 33a in which the throttle valve 32 is built. The throttle body 33a is formed in a metal short cylinder shape, and as shown in FIGS. 4 to 6, the throttle body 33a is positioned leftward and forward with respect to the mounting surface 10a in a posture in which the openings at both ends are directed left and right. Are arranged to be. An air cleaner 31 is connected to the upstream end (left end) of the throttle body 33a via a passage (not shown), while the downstream end (right end) of the throttle body 33a is connected to the downstream side (right side) of the first passage 33. The first passage body 33b, which is a part, is connected.

  As shown in FIG. 6, the first passage body 33 b is configured to connect the throttle body 33 a to the supercharger 34. Specifically, the first passage body 33b is formed in a long cylindrical shape with openings at both ends directed to the left and right. The first passage body 33b is disposed in front of the mounting surface 10a so as to be coaxial with the throttle body 33a. More specifically, the first passage body 33b is formed so as to gradually increase in diameter from the outside in the cylinder row direction toward the inside (from the left side to the right side). As described above, the downstream end of the throttle body 33a is connected to the upstream end (left end) of the first passage body 33b, while the suction port of the supercharger 34 is connected to the downstream end (right end) thereof. ing.

  Further, the first passage body 33b has a junction 33c where the EGR passage 52 joins. As shown in FIG. 6, the merging portion 33 c is formed on the rear surface of the upstream portion of the first passage body 33 b, and the downstream end of the EGR passage 52 is connected thereto. The junction 33c is formed at least downstream of the throttle valve 32.

  In addition, a branch portion 33d that branches to the bypass passage 40 is also opened in the first passage body 33b. The branch portion 33d is formed on the upper surface of the first passage body 33b in the vicinity of the junction portion 33c (substantially the same position with respect to the gas flow direction) and is connected to the upstream end of the bypass passage 40 (see FIG. 10). As shown in FIG. 10 and the like, the branch portion 33d is connected to the supercharger 34, the intercooler 36, the four sets of intake ports 17 and 18, and the intake ports 17 and 18 through an independent passage 39. It is located on the outer side (left side) in the cylinder row direction than the surge tank 38.

  Therefore, the fresh air purified by the air cleaner 31 and flowing into the first passage 33 passes through the throttle valve 32 and then merges with the external EGR gas flowing in from the merging portion 33c. Then, the gas in which the fresh air and the external EGR gas are merged flows into the bypass passage 40 via the branch portion 33d during natural intake, while it is merged with the gas that has flowed back in the bypass passage 40 during supercharging. The supercharger 34 is sucked from the downstream end of the one passage body 33b (see arrow A1 in FIG. 6).

  Hereinafter, the passage structure on the supercharger 34 side and the passage structure on the bypass passage 40 side will be described in order.

-Passage structure on the turbocharger side-
First, the passage structure on the side sucked into the supercharger 34 will be described in detail.

  As described above, the supercharger 34 according to this embodiment is configured as a roots-type supercharger. Specifically, the supercharger 34 includes a pair of rotors (not shown) provided with a rotation shaft extending along the cylinder row direction, a casing 34b that houses the rotor, and a drive pulley 34d that rotationally drives the rotor. The drive shaft 34d is connected to the crankshaft 15 via a drive belt (not shown) wound around the drive pulley 34d. The above-described electromagnetic clutch 34a is interposed between the drive pulley 34d and the rotor, and the driving force is supplied to the supercharger 34 via the crankshaft 15 by switching the cutoff and connection of the electromagnetic clutch 34a. Transmits or interrupts transmission of driving force.

  The casing 34b is formed in a cylindrical shape extending in the cylinder row direction, and divides the housing space of the rotor and the gas flow path passing through the supercharger 34. Specifically, the casing 34b is formed in a cylindrical shape having an opening at the left end and the front surface in the cylinder direction, and as shown in FIG. The first passage 33 and the first passage 33 are arranged so as to be spaced apart from each other.

  A suction port for sucking gas compressed by the rotor is opened at the left end of the casing 34b in the longitudinal direction, and the downstream end (right end) of the first passage 33 is connected. On the other hand, as shown in FIGS. 6 to 7, a discharge port 34c for discharging the gas compressed by the rotor is opened at the front portion (side portion opposite to the engine body 10) of the casing 34b. The upstream end (upper end) of the second passage 35 is connected.

  The drive pulley 34d is configured to rotationally drive the rotor accommodated in the casing 34b. Specifically, the drive pulley 34d is formed in a shaft shape that protrudes from the right end of the casing 34b and extends substantially coaxially with respect to both the first passage 33 and the casing 34b. A drive belt (not shown) is wound around the tip of the drive pulley 34d, and as described above, the crankshaft 15 is connected to the supercharger 34 in accordance with the switching state of the electromagnetic clutch 34a. It is configured.

  The second passage 35 is configured to connect the supercharger 34 to the intercooler 36, as shown in FIG. 4 and FIGS. The second passage 35 according to this embodiment is formed so as to extend along the vertical direction of the engine 1 so that the supercharger 34 and the intercooler 36 are vertically adjacent. Further, as shown in FIG. 7, the upper and lower ends of the second passage 35 are each open toward the rear (the engine body 10 side). Here, the upper opening 35a is connected to the front part of the casing 34b (specifically, the discharge port 34c), and the lower opening 35b is the front part of the intercooler 36 (the front surface of the cooler housing 36c). )It is connected to the.

  Specifically, the second passage 35 is formed as a rectangular tube portion that extends in the up-down direction and is flat in the left-right direction, and both upper and lower end portions are bent toward the rear. That is, as shown in FIG. 7, the second passage 35 is configured to form a substantially U-shaped flow path when viewed in the cylinder row direction (particularly when viewed from the right direction). .

  As described above, the intercooler 36 according to the present embodiment is configured to be water-cooled, and is attached to the core 36a having a gas cooling function and the side portion of the core 36a as shown in FIGS. A core connecting portion 36b and a cooler housing 36c that accommodates the core 36a are provided. Although details are omitted, a water supply pipe for supplying cooling water to the core 36a and a drain pipe for discharging cooling water from the core 36a are connected to the core connecting portion 36b.

  The core 36a is formed in a rectangular shape, and is supported in such a posture that one side surface (rear surface) thereof faces the mounting surface 10a. The front surface of the core 36a constitutes a gas inflow surface, while the rear surface of the core 36a constitutes a gas outflow surface, each being the widest surface of the core 36a. Although not shown, the core 36a has a plurality of water tubes in which a thin plate material is formed into a flat cylindrical shape, and a corrugated fin corrugated fin is connected to the outer wall surface of each water tube by brazing or the like. . By comprising in this way, the cooling water supplied from the water supply pipe is introduce | transduced into each water tube, and cools high temperature gas. The cooling water warmed by cooling the gas is discharged from each water tube through the drain pipe. 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 FIG. 4, the core connecting portion 36b is a rectangular thin plate-like member, and is attached to the right side surface of the core 36a. The water supply pipe, the drain pipe, and the water tube are connected to each other through the core connection portion 36b. The core connecting part 36b constitutes the right side wall part of the intercooler 36, and partitions the accommodation space for the core 36a together with the cooler housing 36c.

  The cooler housing 36 c is disposed below the casing 34 b, defines a housing space for the core 36 a, and flows between the second passage 35 and the third passage 37 in the intake passage 30. Constitutes the road.

  Specifically, the cooler housing 36c is formed in a rectangular thin box shape in which a front surface and a rear surface are opened, and is supported in a posture where the rear surface and the mounting surface 10a face each other at a position below the casing 34b. Yes. Similar to the casing 34b, the rear surface is disposed at a predetermined interval (see FIG. 7) with respect to the mounting surface 10a of the engine body 10.

  The downstream end of the second passage 35 is connected to the opening 36d on the front side of the cooler housing 36c, while the upstream end of the third passage 37 is connected to the opening 36e on the rear side. . The cooler housing 36c also has an opening on the right side. The opening is configured as an insertion port when the core 36a is accommodated in the cooler housing 36c, and is closed by the core connecting portion 36b.

  The third passage 37 is a member formed integrally with the surge tank 38 and the independent passage 39, and is configured to connect the intercooler 36 to the surge tank 38 as shown in FIGS. Yes. Specifically, the third passage 37 is fastened to the cooler housing 36c in order from the upstream side, and a collecting portion 37a where the gas that has passed through the intercooler 36 gathers, and an introduction that guides the gas gathered in the collecting portion 37a to the surge tank 38. Part 37b. The third passage 37 is disposed below the surge tank 38 at least in a vehicle-mounted state.

  The collective portion 37a is formed in a shallow box shape with front and rear depths opened on the front side, that is, the cooler housing 36c side, and the open portion is an opening on the rear side of the cooler housing 36c as shown in FIG. 36e. The collective portion 37a is positioned in the gap between the rear surface of the cooler housing 36c and the mounting surface 10a of the engine body 10. Moreover, the upstream end of the introduction part 37b is further connected to the rear surface of the gathering part 37a.

  The introduction portion 37b 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 37a, while its downstream end is the central portion of the bottom surface of the surge tank (FIGS. 8 to 8). 9). As shown in FIG. 7 and the like, the introducing portion 37b sews a gap between the region from the rear surface of the collecting portion 37a to the rear surface of the casing 34b of the supercharger 34 and the mounting surface 10a of the engine body 10. It is extended.

  More specifically, as shown in FIG. 8, the upstream portion of the introduction portion 37b extends obliquely upward to the right from the connecting portion with the collecting portion 37a, while the downstream portion thereof is connected to the surge tank 38. It is formed to extend directly upward toward the connecting portion. As a result of this formation, the downstream end portion of the introduction portion 37b extends in a direction substantially orthogonal to the gas flow direction in the independent passage 39 when viewed from one side in the cylinder row direction (FIG. 7).

  The surge tank 38 is formed in a substantially cylindrical shape extending in the cylinder row direction and closed at both ends in the same direction. As described above, the surge tank 38 is disposed opposite to the opposite ends of the intake ports 17 and 18 on the opposite side of the plurality of independent passages 39 (see FIG. 7). As will be described later, when each of the plurality of independent passages 39 is formed in a short cylindrical shape, the surge tank 38 is positioned near the inlets (upstream end portions) of the intake ports 17 and 18 in combination with such an arrangement. It will be. This is effective in shortening the flow path length (runner length) from the surge tank 38 to the intake ports 17 and 18.

  Further, as shown in FIG. 9, the downstream end of the third passage 37 (introduction portion 37 b) is connected to the bottom of the surge tank 38. An introduction port 38b having a substantially circular cross section is opened at the center portion of the inner bottom surface 38a of the surge tank 38 (specifically, the center portion in the cylinder row direction), and the downstream end portion of the introduction portion 37b is And, it is connected to the surge tank 38 through the introduction port 38b.

  The introduction port 38b is formed to have a larger diameter than the intake ports 17 and 18.

  In the surge tank 38, the dimension from the introduction port 38b to one end (the end on the first cylinder 11A side) in the cylinder row direction is substantially equal to the dimension from the other end (the end on the fourth cylinder 11D side). It has become. By adopting such a configuration, it becomes possible to ensure the distribution performance of intake air, which is advantageous in reducing the difference in charging efficiency between cylinders.

  Further, as shown in FIG. 9, the upstream end of each of the plurality of independent passages 39 is connected to the surge tank 38 in a line in the order in which the corresponding intake ports 17 and 18 are arranged.

  Specifically, on the side surface (rear surface) of the surge tank 38 on the engine body 10 side, four sets (that is, a total of eight) with two independent passages 39 forming one set along the cylinder row direction are arranged. Is formed. Each of the eight independent passages 39 is formed as a short cylindrical passage extending substantially straight rearward in the vehicle mounted state, and one end side (upstream side) thereof communicates with the space in the surge tank 38. On the other hand, the other end side (downstream side) is open to the engine body 10 side (rear side).

  The four sets of independent passages 39 are arranged so as to correspond to the four sets of intake ports 17, 18, respectively, and include the integrally formed third passage 37, surge tank 38, and independent passage 39. When assembled to the engine body 10, each independent passage 39 and the corresponding intake ports 17 and 18 constitute a single passage.

  As described above, the independent passage 39 is composed of the independent passage 391 corresponding to the first port 17 and the independent passage 392 corresponding to the second port 18 for each set. When the third passage 37, the surge tank 38, and the independent passage 39 are assembled to the cylinder block 12, the first port 17 and the corresponding independent passage 391 constitute one independent passage, The port 18 and the independent passage 392 corresponding to the port 18 constitute an independent passage. In this way, eight independent passages are configured.

  The SCV 80 is disposed in the independent passage 392 connected to the second port 18 (see FIG. 7 and FIG. 11). Since the flow rate of the gas passing through the second port 18 is reduced by reducing the opening of the SCV 80, the flow rate passing through the other first port 17 can be relatively increased.

  By the way, as will be described later, the downstream portion of the bypass passage 40 is bifurcated, and the downstream end portions of the branched passages (hereinafter also referred to as “branch passages” 46R and 46L) are both surge tanks. The branch passages 46R and 46L are examples of “upstream independent passages”, respectively.

  In order to realize such a structure, two first and second introductions are arranged on the upper surface of the surge tank 38 at intervals in the cylinder row direction and configured to communicate the inside and outside of the surge tank 38. Portions 38c and 38d are provided.

  Of the two first and second introduction portions 38c and 38d, the first introduction portion 38c located on one side (right side) in the cylinder row direction has one branch passage (hereinafter referred to as "first branch passage"). The downstream end portion of 46R is connected to the second introduction portion 38d located on the other side (left side), and downstream of the other branch passage (hereinafter also referred to as “second branch passage”) 46L. The ends are connected (see also FIG. 13).

  Specifically, the first and second introduction portions 38c and 38d are both formed in a short cylinder shape, and as shown in FIG. 8, are perpendicular to the cylinder row direction from the upper surface of the surge tank 38 and , Extending obliquely upward and forward.

  As shown in FIG. 8, the first introduction portion 38c is disposed so as to face a portion in the vicinity of the independent passage 392 corresponding to the second port 18B of the second cylinder 11B. On the other hand, the second introduction portion 38d is disposed so as to face a portion in the vicinity of the independent passage 392 corresponding to the second port 18D of the fourth cylinder 11D.

  The gas sucked into the supercharger 34 reaches each cylinder 11 through the “supercharge passage” thus configured.

  That is, during supercharging, while the engine 1 is operating, the output from the crankshaft 15 is transmitted via the drive belt and the drive pulley 34d to rotate the rotor. As the rotor rotates, the supercharger 34 compresses the gas sucked from the first passage 33 and then discharges it from the discharge port 34c. The discharged gas flows into the second passage 35 disposed in front of the casing 34b.

  As indicated by an arrow A2 in FIG. 7, the gas discharged from the supercharger 34 and flowing into the second passage 35 flows forward from the discharge port 34c of the supercharger 34 and then flows into the second passage 35. It flows down along. The gas flowing downward reaches the lower portion of the second passage 35 and then flows backward toward the intercooler 36.

  Subsequently, as shown by an arrow A3 in FIG. 7, the gas that has passed through the second passage 35 flows into the inside of the cooler housing 36c from the opening 36d on the front surface side, and flows backward from the front side thereof. The gas flowing into the cooler housing 36c is cooled by the cooling water supplied to the water tube when passing through the core 36a. The cooled gas flows out from the opening 36e on the rear surface side in the cooler housing 36c and flows into the third passage 37.

  As shown by an arrow A4 in FIG. 7, the gas flowing into the third passage 37 from the intercooler 36 passes through the collecting portion 37a and then flows obliquely upward to the right along the upstream portion of the introducing portion 37b ( 8 (see also section S1 in FIG. 8), and then flows directly upward along the downstream portion of the introduction portion 37b (see also section S2 in FIG. 8). As shown by an arrow A5 in the figure, the gas that has passed through the introduction portion 37b flows into a substantially central space in the surge tank 38 in the cylinder row direction, and is temporarily stored in the surge tank 38, and then independently. It is supplied to each cylinder 11 through a passage 39.

-Passage structure on the bypass side-
Next, the configuration on the bypass passage 40 side will be described in detail.

  10 is a view showing the passage structure according to the bypass passage 40 as seen from the front side, FIG. 11 is a view showing it from the rear side, and FIG. 12 is a view showing it from the upper side. is there. FIG. 13 is a partially enlarged view of FIG. 14 is a longitudinal sectional view showing a connection structure between the surge tank 38 and the bypass passage 40, and FIG. 15 is a transverse sectional view thereof.

  The bypass passage 40 is formed as a so-called tournament-type passage, and in order from the upstream side along the gas flow direction, the valve body 41a in which the bypass valve 41 is incorporated, and the flow direction of the gas that has passed through the valve body 41a As an upstream independent passage that branches from the downstream end of the upstream shared passage 45, and the upstream shared passages 43 to 45 configured to guide the gas that has passed through the curved pipe portion 42. The first and second branch passages 46R and 46L are included. In the present embodiment, the upstream side shared passages 43 to 45 are all configured as resin pipe portions. The material of the upstream shared passages 43 to 45 is not limited to this.

  Specifically, the valve body 41a is formed in a short cylindrical shape, and is disposed in a posture in which the openings at both ends are directed vertically above the first passage 33 as shown in FIGS. . Further, like the first passage 33, the valve body 41a is located in front of the portion near the left end of the mounting surface 10a. The branch end 33d of the first passage 33 is connected to the upstream end (lower end) of the valve body 41a, while the upstream end (lower end) of the curved pipe portion 42 is connected to the downstream end (upper end) of the valve body 41a. It is connected.

  The curved pipe portion 42 is configured as an elbow-shaped pipe joint, and is arranged in a posture in which the opening is directed downward and to the right in the upper position of the first passage 33 and eventually the valve body 41a. Therefore, the gas flowing into the curved pipe portion 42 flows in a direction perpendicular to the main flow of gas in the first passage 33 (directly above), and then the flow direction is adjusted according to the bending direction of the curved pipe portion 42. It is done. As a result, the gas flowing through the curved pipe portion 42 flows slightly rearward from the outside in the cylinder row direction (from the left side to the right side) when viewed in the cylinder axial direction (see FIG. 12). Flowing. Further, similarly to the first passage 33 and the valve body 41a, the curved pipe portion 42 is located in front of the portion near the left end of the mounting surface 10a. As described above, the downstream end (upper end) of the valve body 41a is connected to the upstream end (lower end) of the curved pipe portion 42, while the first passage is connected to the downstream end (right end) of the curved pipe portion 42. The upstream end (left end) of the portion 43 is connected.

  The upstream shared passages 43 to 45 are continuous from the first passage portion 43 extending along the direction from one side to the other side in the cylinder row direction, and the downstream end portion of the first passage portion 43, and are separated from the surge tank 38. After extending in such a manner, when viewed in the cylinder axial direction (that is, when viewed as shown in FIG. 12), it is bent so as to be directed in the surge tank direction indicating the direction perpendicular to the cylinder row direction and toward the surge tank 38. After the second passage 44 and the downstream end of the second passage 44 are continuous and extend along the surge tank direction, the first and second branch passages 46R and 46L branch off from the downstream end. 3 passage portions 45. In this configuration example, the surge tank direction is equal to the direction from the front side to the rear side.

  Specifically, the first passage portion 43 is formed in a long cylindrical shape extending in the left-right direction, and is disposed above the first passage 33 or the supercharger 34 as can be seen from FIGS. 4 to 5. Yes. The upstream end (left end) of the first passage portion 43 opens toward the left, and the downstream end (right end) of the curved pipe portion 42 is connected as described above. On the other hand, the downstream end (right end) of the first passage portion 43 opens forward, and the upstream end (left end) of the second passage portion 44 is connected.

  The second passage portion 44 is formed in a cylindrical shape extending coaxially with the first passage portion 43, and is disposed above the supercharger 34 as viewed in the cylinder axial direction, as shown in FIG. The upstream end (left end) of the second passage portion 44 opens toward the rear, and the downstream end (right end) of the first passage portion 43 is connected as described above. On the other hand, the downstream end (right end) of the second passage portion 44 also opens rearward, and the upstream end (front end) of the third passage portion 45 is connected.

  The second passage portion 44 is offset by a predetermined amount forward from the first passage portion 43. In the present embodiment, the offset amount is set to a value that is half or more of the passage width of the first passage portion 43, as shown by the interval W in FIG.

  Further, in the vicinity of the downstream end of the second passage portion 44, a bulging portion 44b bulging to the right is formed. As shown in FIGS. 10 to 12, the bulging portion 44 b is configured as a semicircular curved surface projecting to the right side, and the wall surface of the portion of the third passage portion 45 extending along the surge tank direction. It bulges to the right of 45a.

  The 3rd channel | path part 45 is formed in the cylinder shape flat in the left-right direction, and is extended toward diagonally lower back. The upstream end (front end) of the third passage portion 45 opens toward the front, and the downstream end (right end) of the second passage portion 44 is connected as described above. On the other hand, from the downstream end (rear end) of the third passage portion 45, the first and second branch passages 46R and 46L branch in a tournament shape.

  The first branch passage 46R extends rightward along the cylinder row direction from the downstream end of the third passage portion 45, and is then bent obliquely downward and rearward. On the other hand, the second branch passage 46L extends from the downstream end of the third passage portion 45 to the left along the cylinder row direction, and is then bent obliquely downward and rearward. The downstream end portions of the first and second branch passages 46R and 46L both extend in the surge tank direction. As shown in FIG. 14 and the like, the surge tank 38 includes a plurality of independent passages 391 and 392, respectively. It is connected to the site | part which opposes with respect to the upstream edge part.

  During natural intake, the gas flowing into the bypass passage 40 passes through each part constituting the passage 40 and reaches each cylinder 11.

  That is, the gas that has passed through the throttle valve 32 flows into the valve body 41 a of the bypass valve 41 from the middle of the first passage 33 according to the open / close state of the bypass valve 41.

  As shown by an arrow A6 in FIG. 12, the gas that has passed through the valve body 41a and has flowed into the curved pipe portion 42 flows rightward, and then flows to the right while slightly moving backward.

  Subsequently, the gas that has passed through the curved pipe portion 42 flows to the right along the first passage portion 43 as shown by an arrow A <b> 7 in FIG. 12, and then flows into the second passage portion 44. The gas passing through the first passage portion 43 is directed from the left side to the right side.

  Subsequently, as indicated by an arrow A8 in FIGS. 12 to 13, the gas flowing into the second passage portion 44 from the first passage portion 43 is being guided forward (that is, in a direction away from the surge tank 38). According to the directivity imparted when passing through the first passage portion 43, it flows toward the right. At this time, as shown in FIG. 13, at least a part of the gas guided forward is a wall surface that separates from the surge tank 38 among the wall surfaces that define the second passage portion 44 (that is, the front side gas). Wall surface) 44a. Other gases also flow so as to be dragged by the gas depending on the flow rate of the gas flowing along the wall surface 44a.

  Subsequently, as indicated by an arrow A9 in FIGS. 12 to 13, among the gases that have flown to the vicinity of the downstream end of the second passage portion 44, the gas that has flowed along at least the front wall surface 44 a Before flowing into the third passage portion 45 from 44, it once passes through the bulging portion 44b. For other gases, there are both gases that pass through the bulging portion 44b and those that do not pass.

  Subsequently, as indicated by an arrow A9 in FIGS. 12 to 13, the gas flowing into the third passage portion 45 flows at least along the front wall surface 44a in the second passage portion 44, and then bulges 44b. Is passed along the wall surface 45a located on the right side in the cylinder row direction among the wall surfaces defining the third passage portion 45. The gas flowing along the wall surface 45a is directed to flow toward the surge tank according to the so-called Wall-guided effect. The gas flow velocity vector so directed will be directed toward the surge tank. For other gases, depending on the flow rate of the gas flowing along the wall surface 45a, the same directivity is imparted by being dragged by the gas.

  Then, as shown by arrows A10 and A11 in FIGS. 12 to 13, the gas that has passed through the third passage portion 45 is distributed to the first branch passage 46R and the second branch passage 46L. It flows into the surge tank 38 (see also FIGS. 14 to 15). The gas flowing into the surge tank 38 is sucked into each cylinder 11 through the independent passages 391 and 392.

(Regarding differences in the amount of gas introduced between cylinders)
The engine 1 includes an ECU for operating the engine 1. The ECU determines the operating state of the engine 1 based on detection signals output from various sensors, and calculates control amounts of various actuators. Then, the ECU sends control signals corresponding to the calculated control amount to the electromagnetic waves of the injector 6, spark plug 25, intake electric VVT 23, exhaust electric VVT 24, fuel supply system 61, throttle valve 32, EGR valve 54, and supercharger 34. The power is output to the clutch 34a and the bypass valve 41, and the engine 1 is operated.

  The operation region of the engine 1 is divided by, for example, the engine speed and the load, and the ECU controls each actuator so as to realize an operation state suitable for each region.

  For example, in an operation region on the lower load side than a predetermined load (hereinafter referred to as “fuel consumption region”), the engine 1 is operated by natural intake, while an operation region on the higher load side than the predetermined load (hereinafter referred to as “supercharging”). In the “zone”), the supercharger 34 is driven to supercharge the gas introduced into each cylinder 11.

  Further, the ECU closes the SCV 80 in order to promote the generation of swirl in the fuel efficiency region. As a result, the flow rate of the gas passing through the first port 17 is increased, and gas mixing can be promoted. On the other hand, in the supercharging region, the ECU gradually opens the SCV 80 as the load on the engine 1 increases in order to ensure the amount of gas introduced.

  FIG. 16 is a view corresponding to FIG. 12 showing a conventional bypass passage 1040. The bypass passage 1040 shown in FIG. 16 is also configured as a tournament-type passage, and a curved pipe portion 1042 that guides gas upward, and a straight pipe portion 1043 that guides the gas that has passed through the curved pipe portion 1042 to the right. The bent pipe portion 1044 that is bent obliquely downward and rearward and guides the gas that has passed through the straight pipe portion 1043 toward the rear, and is branched into two branches from the downstream end of the bent pipe portion 1044 and connected to the surge tank 38. Branch pipe sections 1045R and 1045L.

  Here, when the tournament-type bypass passage 1040 as shown in FIG. 16 is used, if the engine 1 is operated as described above, the branch pipe portion 1045R connected to the right side in the cylinder row direction, and the left side The inventors of the present application have found that there is a possibility that the amount of gas introduced may vary between the branch pipe portion 1045L to be connected.

  That is, the gas flowing through the bypass passage 1040 is directed in the direction from the left side to the right side in the cylinder row direction when passing through the straight pipe portion 1043. Then, among the plurality of branch pipe portions 1045R and 1045L, the branch pipe portion 1045R located on the right side in the cylinder row direction is relatively easy to flow gas, while the branch pipe portion 1045L located on the left side in the cylinder row direction. As for, it becomes harder for gas to flow. Such a situation is not desirable for evenly distributing the gas to each cylinder 11.

  Accordingly, it is conceivable that a passage extending in the surge tank direction is interposed between the bent pipe portion 1044 and the branch pipe portions 1045R and 1045L, instead of branching from the downstream end of the bent pipe portion 1044. In this case, the gas flowing through the bypass passage 1040 flows along the wall surface of the passage extending in the surge tank direction, so that directivity from the left side to the right side in the cylinder row direction is reduced and directed in the surge tank direction. Become so. As a result, the gas can be evenly distributed to the branch pipe portions 1045R, 1045L, and eventually to the cylinders 11, on the right and left sides in the cylinder row direction.

  In order to distribute the gas evenly to the branch pipe portions 1045R and 1045L, it is required to flow the gas along the wall surface of the portion extending in the surge tank direction. In that respect, simply providing a passage extending in the direction of the surge tank does not necessarily satisfy such a requirement, and there is room for improvement.

  In the first place, if a passage extending in the surge tank direction is provided in the middle of the bypass passage 1040, the straight pipe portion 1043 and the bent pipe portion 1044 are separated from the surge tank 38 in accordance with the dimensions of the passage. For this reason, there is a risk of hindering the layout of the intake passage in a compact manner. On the other hand, in order to reliably reduce the gas directivity, it is required to extend the passage extending in such a direction as long as possible.

  On the other hand, in the present embodiment, the gas flowing through the bypass passage 40 is directed from the left side in the cylinder row direction to the right side when passing through the first passage portion 43, but the arrow A8 in FIG. As shown, when flowing from the first passage portion 43 to the second passage portion 44, it is guided in a direction away from the surge tank 38. At least a part of the gas thus guided flows along the wall surface 44 a on the side away from the surge tank 38 among the wall surfaces defining the second passage portion 44.

  As shown in FIG. 12 and the like, at least a part of the third passage portion 45 includes a portion extending in the surge tank direction, so that the second passage portion 44 and the third passage portion 45 are continuous. Of the gas flowing from the second passage portion 44 to the third passage portion 45, the gas flowing along the wall surface 44a in the second passage portion 44 is indicated by an arrow A9 in FIG. As shown, it is guided so as to flow along the wall surface 45a of the portion extending in the surge tank direction, particularly the portion located on the right side in the cylinder row direction. As a result, the directivity from the left side to the right side in the cylinder row direction can be reduced and directed in the surge tank direction. As a result, the gas can be evenly distributed to the first and second branch passages 46R and 46L, and thus to each cylinder 11.

  Further, as shown in FIG. 12 and the like, the third passage portion 45 can be extended in the surge tank direction by the amount that the second passage portion 44 is once extended away from the surge tank 38. This is effective in directing the gas toward the surge tank. In addition, with respect to the first passage portion 43, for example, an arrangement can be maintained so as to be along the mounting surface 10a of the engine body 10. Therefore, the intake passage 30 can be laid out more compactly compared with a configuration in which a portion extending in the surge tank direction is simply provided.

  Therefore, the gas can be evenly distributed to each cylinder 11 while the intake passage 30 is laid out in a compact manner.

  Further, as described above, at least a part of the gas flowing from the first passage portion 43 to the second passage portion 44 is guided in a direction away from the surge tank 38, and then the second passage portion 44 is partitioned. Of the wall surfaces to be flowed, it flows along the wall surface 44a on the side away from the surge tank 38. The gas flowing along such a wall surface 44 a once passes through the bulging portion 44 b before flowing into the third passage portion 45 from the second passage portion 44.

  As a result of intensive studies by the inventors of the present application, according to the obtained knowledge, it is possible to reduce the directivity due to the gas being guided away from the surge tank 38 by passing the bulging portion 44b. it can.

  As shown in FIGS. 10 to 12, the burned gas that flows into the bypass passage 40 from the EGR passage 52 by connecting the downstream end portion of the EGR passage 52 to at least the upstream side of the second passage portion 44. Will pass through the second passage 44 in the same manner as other gases such as fresh air. As a result, the burned gas is also guided in a direction away from the surge tank 38, so that it can be evenly distributed to the cylinders 11.

  Further, as shown in FIG. 11 and the like, the merging portion 33c of the EGR passage 52 is disposed in the vicinity of the branch portion 33d in the intake passage 30, so that the supercharging passage (supercharger 34, second passage 35, interfacing) Burned gas can be introduced into both the cooler 36 and the third passage 37) and the bypass passage 40. Further, for example, the EGR passage 52 can be laid out more compactly as compared with a configuration in which the joining portion 33c is spaced upstream from the branching portion 33d.

  Further, as shown in FIG. 12 and the like, since the second passage portion 44 is disposed above the supercharger 34, considering that the second passage portion 44 is made of resin, for example, the engine 1 When the vehicle on which the vehicle is mounted collides, the second passage portion 44 can be used as a cushion without causing the collision object and the supercharger 34 to directly collide with each other.

  The third passage 37 constituting the supercharging passage instead of the bypass passage 40 extends through the vertical direction in the vehicle mounted state, and then passes through the introduction port 38b opened at the center in the cylinder row direction of the surge tank 38. It is connected to the surge tank 38.

  With this configuration, the gas distribution performance is given priority for the bypass passage 40 as described above, while a simpler layout than the bypass passage 40 can be realized for the supercharging passage.

  The bypass passage 40 is also effective from the viewpoint that the curved pipe portion 42 can be freely configured. That is, depending on the shape of the curved pipe portion 42, directivity is imparted to the gas passing through the curved pipe portion 42, as described above, by the second passage portion 44 and the third passage portion 45, Such directivity can be eliminated. As a result, the bending direction of the curved pipe portion 42 can be freely changed. This is effective in various aspects including downsizing of the intake passage 30.

  Further, the engine 1 is provided with a negative overlap period (hereinafter referred to as “NVO”) in which both the intake valve 21 and the exhaust valve 22 are closed with the exhaust top dead center interposed therebetween in the above-described fuel consumption region. The internal EGR gas is confined in the interior, and the closing timing of the intake valve 21 is set during the compression stroke (hereinafter referred to as “slow closing”) in accordance with the setting of NVO, thereby realizing a delayed closing type mirror cycle. It is supposed to be.

  However, when such control is executed, the intake valve 21 remains open immediately after the transition from the intake stroke to the compression stroke, so that the internal EGR introduced into the cylinder 11 as the piston 14 moves up. Gas comes back to the intake side.

  In the case of a four-cylinder engine, the gas blown back from the cylinder 11 located inside the cylinder row direction, such as the second cylinder 11B and the third cylinder 11C, can be diffused to both the left and right in the cylinder row direction. Since the gas blown back from the cylinders 11 located at both ends in the cylinder direction, such as the first cylinder 11A and the fourth cylinder 11D, has only a place on the left and right sides in the cylinder row direction, it can be sufficiently diffused. I can't.

  Therefore, in the surge tank 38, the blown-back gas tends to stay in the space on both end sides in the cylinder row direction as compared with the space on the central side.

  Therefore, it can be considered that the internal EGR gas staying at the end side is swept away by the fresh air introduced from the intake passage 30. In order to realize such a measure, it is required to introduce fresh air evenly to each part of the surge tank 38.

  The above-described configuration is effective in satisfying such a demand in that fresh air can be introduced in a balanced manner on one side (right side) and the other side (left side) of the surge tank 38.

  Further, even in the fuel economy region, in the relatively high load operation region, the flow rate of the gas flowing along the wall surface 45a of the third passage portion 45 is relatively small, while the central axis of the third passage portion 45 is The flow rate of the gas flowing in the vicinity increases relatively. As described above, by being dragged by the gas flowing along the wall surface 45a, the directivity of the gas flowing near the central axis can be adjusted appropriately. Therefore, as shown in FIG. 12, even if the wall surface 45a is disposed on the right side, the flow rate of the gas flowing in the vicinity of the central axis is relatively increased, so that the gas can be distributed in a balanced manner on the left and right.

<< Other embodiments >>
In the said embodiment, although the inline 4 cylinder engine was illustrated, it is not restricted to this structure. For example, an engine having at least three or more cylinders such as an in-line 3-cylinder engine or an in-line 6-cylinder engine may be used. Further, the number of passages branched as upstream independent passages may be changed according to the number of cylinders.

  In the said embodiment, although the 1st channel | path part 43-the 3rd channel | path part 45 were all formed from resin, it is not limited to this structure. For example, you may comprise the 1st channel | path part 43 with a hose.

  The configuration around the second passage portion 44 can also be changed as appropriate. For example, the portion from the downstream end of the first passage portion 43 to the upstream end of the second passage portion 44 need not be parallel to the surge tank direction. As long as it is a direction away from the surge tank 38, it may extend obliquely with respect to the front-rear direction.

1 engine (multi-cylinder engine)
11 cylinders
17 First port (intake port)
18 Second port (intake port)
30 Intake passage 33c Merging portion 33d Branching portion 34 Supercharger (supercharging passage)
35 Second passage (supercharging passage)
36 Intercooler (supercharged passage)
37 3rd passage (supercharging passage)
38 Surge tank 38b Inlet 39 Independent passage (downstream independent passage)
40 Bypass passage 43 1st passage part (upstream side common passage)
44 Second passage (upstream shared passage)
44b bulging portion 45 third passage portion (upstream side common passage)
46R 1st branch passage (branch passage, upstream independent passage)
46L 2nd branch passage (branch passage, upstream independent passage)
50 Exhaust passage 52 EGR passage

Claims (6)

A plurality of cylinders each including at least three or more cylinders arranged in a row, a plurality of intake ports communicating with each of the plurality of cylinders, and an intake passage connected to each of the plurality of intake ports. An intake device for a cylinder engine,
The intake passage is
A plurality of downstream independent passages each connected to each of the plurality of intake ports;
A surge tank in which each upstream end of the plurality of downstream independent passages is connected in a line according to the order in which the corresponding cylinders are arranged;
A plurality of upstream independent passages each having a downstream end connected to the surge tank and introducing gas into the surge tank;
An upstream shared passage from which the plurality of upstream independent passages branch from a downstream end, and
The downstream end portions of the plurality of upstream independent passages extend in a surge tank direction perpendicular to the cylinder row direction and indicate a direction toward the surge tank, and the plurality of downstream independent passages in the surge tank. Is connected to a portion facing each upstream end of
The upstream shared passage is in order from the upstream side,
A first passage portion extending along a direction from one side to the other side in the cylinder row direction;
A second passage portion which is continuous from the downstream end portion of the first passage portion and extends so as to be separated from the surge tank, and then bent so as to be directed in the surge tank direction in a cylinder axial view;
Intake of a multi-cylinder engine having a third passage portion that is continuous from the downstream end portion of the second passage portion and extends along the surge tank direction and then the plurality of upstream independent passages branch from the downstream end portion. apparatus. The intake device for a multi-cylinder engine according to claim 1,
A portion of the second passage portion that is bent so as to be directed in the surge tank direction expands to the other side in the cylinder row direction from a portion of the third passage portion that extends along the surge tank direction. An intake device of a multi-cylinder engine in which a protruding bulge is formed. The intake system for a multi-cylinder engine according to claim 1 or 2,
The multi-cylinder engine is
An exhaust passage through which burned gas discharged from each of the plurality of cylinders flows;
An EGR passage that connects the exhaust passage and the intake passage and recirculates a part of the burned gas to the intake passage;
The downstream end portion of the EGR passage is an intake device for a multi-cylinder engine connected to the upstream side of at least the upstream end portion of the second passage portion in the intake passage. The intake device for a multi-cylinder engine according to claim 3,
The multi-cylinder engine includes a supercharger disposed on the opposite side across the surge tank with respect to the plurality of cylinders,
The intake passage includes, on the upstream side of the surge tank, a supercharging passage in which the supercharger is interposed, the plurality of upstream independent passages, and the upstream shared passage, Branched to the bypass passage that bypasses the machine,
A downstream end portion of the EGR passage is an intake device of a multi-cylinder engine connected to the vicinity of the branch portion in the intake passage. The intake system for a multi-cylinder engine according to claim 1 or 2,
The multi-cylinder engine includes a supercharger disposed on the opposite side across the surge tank with respect to the plurality of cylinders,
The intake passage includes, on the upstream side of the surge tank, a supercharging passage in which the supercharger is interposed, the plurality of upstream independent passages, and the upstream shared passage, Branched to the bypass passage that bypasses the machine,
The bypass passage is an intake device for a multi-cylinder engine disposed above the supercharger when viewed in the cylinder axial direction. The multi-cylinder engine intake device according to claim 5,
The supercharging passage extends in the up-down direction in a vehicle-mounted state, and then is an intake of a multi-cylinder engine connected to the surge tank through an inlet port that is open at the center in the cylinder row direction of the surge tank. apparatus.

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