JP2018173012A - 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 44R, 44L having lower ends each connected with the surge tank 38; and a straight pipe 43 which extends in a direction from one side to the other side of a cylinder row direction and is formed so that the first and the second branch passages 44R, 44L are branched from a downstream side end thereof. The first and the second branch passages 44R, 44L are formed in such a manner that an upstream side end continued from the downstream side end of the straight pipe 43 extends from one side to the other side of the cylinder row direction, and after that, a portion downstream of the upstream side end is curved toward a direction of the surge tank.SELECTED DRAWING: Figure 13

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 in the shared passage flows along the wall surface defining the portion extending in the surge tank direction, thereby reducing the 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.

  However, if a straight extending portion is interposed between a portion bent toward the surge tank and a portion branched into a plurality of branch passages, it will hinder the layout of the intake passage in a compact manner. There is a fear.

  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 provided with a branch passage portion that extends in a direction from one side to the other side in the cylinder row direction and is formed such that the plurality of upstream independent passages branch from the downstream end portion. Each of the plurality of upstream independent passages extends from the downstream end portion of the branch passage portion in a direction from one side to the other side in the cylinder row direction, and A portion on the downstream side of the end portion is formed to bend toward the surge tank.

  According to this configuration, the gas flowing through the intake passage is directed in a direction from one side of the cylinder row direction to the other side when passing through the branch passage portion. Here, from the downstream end portion of the branch passage portion, the upstream end portion of each upstream side independent passage is continuous, and these upstream end portions are all in a direction from one side to the other side in the cylinder row direction. It extends. If it does so, the gas to which the above directivity was provided will flow smoothly into each upstream end.

  For example, one of the upstream end portions of the two upstream independent passages extends in a direction from one side to the other side in the cylinder row direction, while the other extends in a direction orthogonal to the same direction. Assuming that the gas directed from one side to the other side in the cylinder row direction is more likely to flow into the former upstream end than the latter upstream end.

  On the other hand, according to the above configuration, since the downstream end portion of the branch passage portion and the upstream end portion of each upstream independent passage extend in the same direction, the directivity imparted when passing through the branch passage portion is provided. Therefore, it is possible to avoid a situation in which a large amount of gas flows into the upstream end portion of any upstream independent passage. As much as the influence of directivity is suppressed, it is advantageous in distributing gas evenly to each upstream side independent passage and thus to each cylinder.

  Further, the gas flowing into each upstream independent passage flows in the surge tank direction when passing through a portion downstream from each upstream end. As a result, the directivity from one side to the other side in the cylinder row direction can be reduced.

  As described above, the intake passage distributes the gas to each upstream independent passage so that the directivity imparted in the branch passage portion does not affect, and reduces the directivity after distributing the gas. It is configured as follows.

  In addition, the above configuration can lay out the entire intake passage more compactly than, for example, a configuration in which a passage extending in the surge tank direction is interposed between the upstream shared passage and each upstream independent passage. .

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

  The upstream end portions of the plurality of upstream independent passages may be arranged in a direction orthogonal to a direction from one side to the other side in the cylinder row direction.

  According to this configuration, it is advantageous for evenly distributing the gas imparted with directivity from one side to the other side in the cylinder row direction to the respective upstream independent passages.

  The plurality of upstream independent passages include first and second upstream independent passages, and the inner wall surface of the downstream end portion of the upstream shared passage has a cross-sectional view perpendicular to the gas flow direction. The inner wall surface on the opposite side to the second upstream independent passage at the upstream end of the first upstream independent passage is a cross section perpendicular to the gas flow direction. The inner wall surface on the second upstream independent passage side is formed in a rectangular shape in the same cross sectional view, and the upstream end portion of the second upstream independent passage is formed in a semicircular shape when viewed. The inner wall surface on the opposite side to the first upstream independent passage is formed in a semicircular shape in a cross-sectional view perpendicular to the gas flow direction, while on the first upstream independent passage side The inner wall surface is formed in a rectangular shape in the same sectional view, The inner wall surfaces downstream of the upstream end portions in the first and second upstream independent passages are both gradually circular in a cross-sectional view perpendicular to the gas flow direction from the respective upstream end portions toward the downstream side. The shape may be deformed so as to approach the shape, and each downstream end portion may be formed to have a circular shape in the same cross-sectional view.

  According to this configuration, each flow path can be smoothly changed while increasing the cross-sectional area as much as possible from the downstream end portion of the branch passage portion to the upstream end portions of the first and second upstream independent passages. Can do. Thereby, while distributing gas smoothly, it becomes possible to suppress channel resistance of each passage.

  The upstream shared passage has a bent portion that is bent so as to be directed in a direction from one side to the other side in the cylinder row direction, and a portion on the upstream side of the bent portion includes the plurality of It is good also as extending in the direction orthogonal to the arrangement direction of the upstream end part of an upstream independent passage.

  According to this configuration, since the portion upstream from the bent portion extends in a direction orthogonal to the arrangement direction of the upstream end of each upstream independent passage, the gas passing through this portion is at least It is not oriented in the line direction.

  If the gas passing through the upstream portion of the bent portion is given directivity that goes from one side to the other side of the arrangement direction, the gas flows in each of the plurality of upstream independent passages. It becomes easy to flow into the upstream end part located in the other side of the arrangement direction among the upstream end parts. Such a situation is not desirable for evenly distributing the gas to each upstream side independent passage and thus to each cylinder.

  On the other hand, according to the above-described configuration, the portion upstream of the bent portion does not give the directivity in the arrangement direction, which is advantageous for evenly distributing the gas to each cylinder. become.

  The multi-cylinder engine connects an exhaust passage through which burned gas discharged from each of the plurality of cylinders flows, the exhaust passage and the intake passage, and a part of the burned gas passes through the intake passage. And an EGR passage that recirculates to the exhaust passage, and a downstream end portion of the EGR passage may be connected to an upstream side of at least the bent portion of the intake passage.

  According to this configuration, the burned gas flowing into the intake passage from the EGR passage is connected to the upstream end of at least the bent portion of the EGR passage in the same manner as other gases such as fresh air. The bent portion, the branch passage portion, and the upstream independent passage are sequentially passed. Thereby, the burned gas 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.

  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 perspective view showing the passage structure related to the bypass passage as viewed obliquely from the rear. FIG. 11 is a view showing a passage structure related to the bypass passage as seen from the front side. FIG. 12 is a view showing the passage structure related to the bypass passage as seen from the rear side. FIG. 13 is a view showing a passage structure related to the bypass passage as viewed from above. FIG. 14 is a partially enlarged view of the bypass passage. FIG. 15A is a diagram showing a cross section of the bypass passage. FIG. 15B is a diagram showing a cross section different from FIG. 15A. FIG. 15C is a diagram showing a cross section different from FIGS. 15A and 15B. FIG. 16 is a cross-sectional view showing a connection structure between the surge tank and the bypass passage. FIG. 17 is a view corresponding to FIG. 13 showing a conventional bypass passage. FIG. 18A is a view corresponding to FIG. 15A showing a first modification of the bypass passage. FIG. 18B is a diagram corresponding to FIG. 15B illustrating a first modification of the bypass passage. FIG. 18C is a view corresponding to FIG. 15C showing a first modification of the bypass passage. FIG. 19 is a view corresponding to FIG. 10 illustrating a second modification of the bypass passage. FIG. 20 is a view corresponding to FIG. 13 illustrating a second modification of the 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 ends of the branched passages (hereinafter also referred to as “branch passages” 44R and 44L) are both surge tanks. 38 is connected to the upper surface. The branch passages 44R and 44L are examples of “upstream independent passages”.

  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 44R 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”) 44L. 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 perspective view showing the passage structure according to the bypass passage 40 as viewed obliquely from the rear, FIG. 11 is a view showing it from the front side, and FIG. 12 is a view showing it from the rear side. FIG. 13 is a view showing the same as viewed from above. FIG. 14 is a partially enlarged view of FIG. 15A to 15C are cross-sectional views of the bypass passage 40. FIG. 16 is a cross-sectional view showing a connection structure between the surge tank 38 and the bypass passage 40.

  The bypass passage 40 is formed as a so-called tournament-type passage, and guides the gas flowing in from the first passage 33 from one side to the other side in the cylinder row direction in order from the upstream side along the gas flow direction. The upstream shared passages 41a, 42 to 43 configured, and the first and second branch passages 44R and 44L as upstream independent passages branched from the downstream ends of the upstream shared passages 41a and 42 to 43 are included. It is configured. The “direction from one side to the other side in the cylinder row direction” refers to a direction from the left side to the right side in the cylinder row direction in the engine 1. Hereinafter, this direction may be simply referred to as “right direction (right direction)”.

  The upstream shared passages 41a and 42 to 43 are connected to the branch portion 33d in order from the upstream side along the gas flow direction, and the valve body 41a in which the bypass valve 41 is built, and the downstream of the valve body 41a. A bent portion 42 which is continuous from the end portion and is bent so as to be directed in the right direction, and is continuous from the downstream end portion of the bent portion 42 and extends in the right direction, and the first and second branch passages from the downstream end portion. 44R, 44L and the straight pipe part 43 formed so that it may branch are provided. The straight pipe portion 43 is an example of a “branch passage portion”.

  Specifically, the valve body 41a is formed in a short cylindrical shape, and is disposed in a position in which the openings at both ends are directed vertically above the first passage 33 as shown in FIGS. Yes. 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 bent portion 42 is connected to the downstream end (upper end) of the valve body 41a. It is connected.

  The valve body 41a extends in a direction (vertical direction) perpendicular to the arrangement direction (front-rear direction) of the upstream end portions of the first and second branch passages 44R, 44L.

  Further, the bypass valve 41 built in the valve body 41a is configured as a so-called butterfly type air bypass valve, and as shown by broken lines in FIGS. 10 and 14, the first and second branch passages 44R, 44L. The valve body 41a is opened and closed by being driven by a rotating shaft extending in the direction in which the upstream end portions are aligned (in this example, the front-rear direction). That is, when the bypass valve 41 is opened, the gas passing through the valve body 41a flows on both the front and back sides (in this example, both the left and right sides) with the bypass valve 41 interposed therebetween. At this time, as a result of the gas flow along the bypass valve 41 being peeled off at the end of the valve 41, different flows may occur between the front side and the back side of the bypass valve 41. However, in this configuration example, the bypass valve 41 opens symmetrically in the front-rear direction, so even if different flows occur between the front side and the back side, the first and second branch passages 44R, Regarding the arrangement direction of the upstream end portions of 44L, the influence can be suppressed.

  The bent portion 42 is configured as an elbow-shaped pipe joint, and is arranged in a posture in which the opening is directed downward and rightward at an upper position of the valve body 41a. Specifically, the bent portion 42 is bent on a plane including the up-down direction and the cylinder row direction (left-right direction), extends upward, and then is bent rightward. As described above, the downstream end (upper end) of the valve body 41a is connected to the upstream end (lower end) of the bent portion 42, while the straight pipe portion is connected to the downstream end (right end) of the bent portion 42. The upstream end (left end) of 43 is connected.

  The straight pipe portion 43 is formed in a rectangular tube shape that extends in the left-right direction and is flat in the up-down direction, and is disposed above the first passage 33 in the same manner as the bent portion 42. The upstream end (left end) of the straight pipe portion 43 opens toward the left, and the downstream end (right end) of the bent portion 42 is connected as described above. As shown in FIGS. 13 to 14, the straight pipe portion 43 is widened in a substantially tapered shape from the upstream end toward the downstream side. The downstream end portion of the straight pipe portion 43 opens toward the right, and as shown in FIG. 15A, a horizontally long and rectangular opening portion C1 having a long longitudinal dimension with respect to the vertical dimension is defined. doing. On the other hand, the upstream end (left end) of the first and second branch passages 44R and 44L branches from the downstream end.

  In addition, the straight pipe part 43 is comprised shorter than the conventional straight pipe part 1043 (refer FIG. 17). In the present embodiment, the downstream end portion of the straight pipe portion 43 is positioned to the left of the second introduction portion 38d of the surge tank 38 at least in the cylinder row direction. More specifically, the downstream end portion of the straight pipe portion 43 extends to the vicinity of the left end portion of the surge tank 38 in the cylinder row direction when viewed in the cylinder axis direction.

  Each of the first and second branch passages 44R and 44L has an upstream end portion extending from the downstream end portion of the straight pipe portion 43 extending in the right direction, and a portion downstream of the upstream end portion is directed to the surge tank. It is formed so as to be curved toward. Here, the “surge tank direction” indicates a direction orthogonal to the cylinder row direction and toward the surge tank 38. Further, the upstream end portions of the first and second branch passages 44R and 44L are arranged in the front-rear direction.

  Specifically, the upstream end portions of the first and second branch passages 44R and 44L are partitioned so as to divide the downstream end portion of the straight pipe portion 43 into two in the front-rear direction. As shown in FIG. 15B, the upstream ends of the first and second branch passages 44R and 44L are arranged in the front-rear direction in a state of being separated by walls extending in the up-down direction and the left-right direction. If comprised in this way, the pressure loss which arises in the front-back direction center part can be suppressed in the part which continues from the downstream end part of the straight pipe part 43 to the upstream end part of 1st and 2nd branch passage 44R, 44L. .

  Specifically, the upstream end of the first branch passage 44R is disposed on the front side, while the upstream end of the second branch passage 44L is adjacent to the rear thereof. Each upstream end portion opens toward the left, and defines vertically long and rectangular openings C2 and C3 whose front-rear dimension is shorter than the vertical dimension. As shown in FIG. 15B, the opening C2 on the first branch passage 44R side and the opening C3 on the second branch passage 44L side have substantially the same shape. For example, as shown in FIG. 14, the width W1 of the opening C2 on the first branch passage 44R side and the width W2 of the opening C3 on the second branch passage 44L side are the same.

  Further, the first branch passage 44R extends from the upstream end portion configured as described above to the right diagonally rearward direction, and is then curved to be inclined diagonally downward and rearward. On the other hand, the second branch passage 44L is bent at a substantially right angle from the upstream end thereof so as to protrude forward and obliquely forward in the cylinder axial direction (when viewed from the viewpoint shown in FIGS. 13 to 14). After being bent, it is curved so as to go diagonally downward and rearward.

  As described above, the downstream end portion of the straight pipe portion 43 is positioned to the left of the second introduction portion 38d of the surge tank 38. Thereby, as shown in FIG. 13, the second branch passage 44L is formed without bending from the right side to the left side.

  The downstream ends of the first and second branch passages 44R, 44L are both extended in the surge tank direction, and as shown in FIG. 14 and the like, the surge tank 38 includes a plurality of independent passages 391, It is connected to the part which opposes each upstream end part of 392. Further, as shown in FIG. 15C, the downstream ends of the first and second branch passages 44R and 44L are connected with an interval in the cylinder row direction, and define circular openings C4 and C5, respectively. ing.

  That is, the inner wall surfaces on the downstream side of the upstream end portions of the first and second branch passages 44R and 44L both gradually in the cross-sectional view perpendicular to the gas flow direction from the respective upstream end portions toward the downstream side. As shown in the openings C4 and C5 in FIG. 15C, the respective downstream end portions are formed so as to reach a circular shape in the same cross-sectional view. Note that the flow path cross-sectional areas of the first and second branch passages 44R and 44L are formed to be minimum at the downstream end portion shown in FIG. 15C.

  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 FIGS. 13 to 14, the gas that has passed through the valve body 41a and has flowed into the bent portion 42 flows rightward and then slightly toward the rear, but then toward the right. Flowing.

  Subsequently, the gas that has passed through the bent portion 42 flows into the straight pipe portion 43 and flows to the right as indicated by an arrow A7 in FIGS. The gas passing through the straight pipe portion 43 is directed from the left side to the right side.

  Subsequently, as shown by arrows A8 and A9 in FIGS. 13 to 14, one of the gases that have passed through the straight pipe portion 43 that flows through the front side flows into the first branch passage 44R, whereas the rear side. The other that flows through flows into the second branch passage 44L.

  And as shown to arrow A8 of FIGS. 13-14, the gas which flowed in into the 1st branch channel | path 44R flows toward the right according to the directivity provided when passing the straight pipe | tube part 43. FIG. Then, it is led to the downstream end along the outer (right side in this example) wall surface of the first branch passage 44R, and is directed to flow toward the surge tank near the downstream end and flows into the surge tank 38. To do.

  On the other hand, as shown by an arrow A9 in FIGS. 13 to 14, the gas flowing into the second branch passage 44 </ b> L flows toward the right according to the directivity imparted when passing through the straight pipe portion 43. Then, it is guided to the downstream end along the outer wall surface (left side in this example) in the second branch passage 44L, and is directed to flow in the surge tank direction near the downstream end and flows into the surge tank 38. To do.

  The gas flowing into the surge tank 38 from the first and second branch passages 44R and 44L is sucked into the cylinders 11 via the independent passages 391 and 392 (see also FIG. 16).

(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. 17 is a view corresponding to FIG. 13 showing a conventional bypass passage 1040. The bypass passage 1040 shown in FIG. 17 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. 17 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.

  However, if a passage extending in the surge tank direction is provided in the middle of the bypass passage 1040, depending on the size of the passage, there is a risk of hindering a compact layout of the intake passage.

  On the other hand, in this embodiment, as shown in FIGS. 13 to 14, when the gas flowing through the bypass passage 40 passes through the straight pipe portion 43, a direction (from one side to the other side in the cylinder row direction) ( In this example, it is directed in the right direction). Here, the upstream end portions of the first and second branch passages 44R and 44L are continuous from the downstream end portion of the straight pipe portion 43, and these upstream end portions are both from one side in the cylinder row direction. It extends in the direction toward the other side. If it does so, the gas to which the above directivity was provided will flow smoothly into each upstream end.

  For example, one of the first and second branch passages 44R and 44L extends in a direction from one side to the other side in the cylinder row direction, while the other extends in a direction orthogonal to the same direction. Assuming that the gas directed from one side to the other side in the cylinder row direction is more likely to flow into the former upstream end than the latter upstream end.

  On the other hand, in the bypass passage 40, as shown in FIGS. 13 to 14 and the like, the downstream end portion of the straight pipe portion 43 and the upstream end portions of the first and second branch passages 44R and 44L extend in the same direction. Therefore, it is possible to avoid a situation in which a large amount of gas flows into the upstream end portion of one of the branch passages due to the directivity imparted when passing through the straight pipe portion 43. Become. As much as the influence of directivity is suppressed, it is advantageous to distribute the gas evenly to the first and second branch passages 44R and 44L, and thus to each cylinder 11.

  Further, when the gas flowing into each of the first and second branch passages 44R and 44L passes through the downstream portion of each upstream end as shown by arrows A8 to A9 in FIGS. In addition, it flows toward the surge tank. As a result, the directivity from one side to the other side in the cylinder row direction can be reduced.

  Thus, the bypass passage 40 distributes the gas to each of the first and second branch passages 44R and 44L so that the directivity imparted in the straight pipe portion 43 does not affect the bypass passage 40. Later, the directivity is configured to be reduced.

  In addition, the bypass passage 40 can be laid out more compactly than the bypass passage 40 ', as compared with the passage extending in the surge tank direction in the middle of the bypass passage 40' as described above.

  In addition, the bypass passage 40 has, for example, a configuration in which the downstream end portion of the straight pipe portion 43 and the upstream end portions of the first and second branch passages 44R and 44L extend in different directions, respectively. The periphery of the branch portion (the portion where the first and second branch passages 44R and 44L branch from the straight pipe portion 43) can be configured compactly.

  Thus, the gas can be evenly distributed to each cylinder 11 while the bypass passage 40 is laid out in a compact manner.

  Further, as shown in FIGS. 10 to 13 and the like, the upstream ends of the first and second branch passages 44R and 44L are arranged in a direction (front-rear direction) orthogonal to the cylinder row direction. When passing through the portion 43, it is advantageous for evenly distributing the gas imparted with directivity from one side to the other side in the cylinder row direction to each of the first and second branch passages 44R and 44L. become.

  In addition, the arrangement direction of the upstream end portions of the first and second branch passages 44R and 44L is not only in the cylinder row direction but also in the extending direction (vertical direction) of the valve body 41a and the bending direction of the bent portion 42. Even they are orthogonal. This is also effective for evenly distributing the gas to each of the first and second branch passages 44R and 44L.

  In other words, if the gas passing through the valve body 41a is given directivity such as going from the rear side to the front side in the arrangement direction, the gas flows in the first and second branch passages 44R and 44L. Of the upstream end portion, the air easily flows into the upstream end portion of the first branch passage 44R located on the front side in the arrangement direction. Such a situation is not desirable for evenly distributing the gas to each cylinder 11.

  On the other hand, the valve body 41a according to this embodiment provides directivity in a direction orthogonal to the arrangement direction, but does not provide directivity in the arrangement direction. This is advantageous for evenly distributing the gas.

  Further, as shown in FIGS. 13 to 14 and the like, 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 bent portion 42. As with other gases such as fresh air, the gas passes through the bent portion 42, the straight pipe portion 43, and the first and second branch passages 44R and 44L in order. Thereby, the burned gas can be evenly distributed to each cylinder 11.

  Further, as shown in FIG. 13 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 (the supercharger 34, the second passage 35, the interface) 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 FIGS. 7 to 8 and the like, the third passage 37 constituting the supercharging passage extends along the vertical direction in the vehicle mounted state, and then opens at the center of the surge tank 38 in the cylinder row direction. It is connected to the surge tank 38 through the introduction port 38b.

  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.

  As shown in FIGS. 10 and 14, the bypass valve 41 is opened and closed by a rotating shaft extending in the direction in which the upstream ends of the first and second branch passages 44R and 44L are aligned. Even if the gas passing through 41 has different flows on the front side and the back side of the valve 41, the influence on the arrangement direction of the upstream end portions can be suppressed. This is effective for evenly distributing the gas to each of the first and second branch passages 44R and 44L.

  Further, as shown in FIG. 13, the straight pipe portion 43 is formed shorter than the conventional straight pipe portion 1043. Specifically, the downstream end portion of the straight pipe portion 43 is positioned to the left of the second introduction portion 38d of the surge tank 38 as described above. Thereby, as shown in FIG. 13, the second branch passage 44L is formed without bending from the right side to the left side.

  If a part of the second branch passage 44L is bent from the right side to the left side, the bending direction is opposite to the direction directed at the straight pipe portion 43. Therefore, the pressure in the second branch passage 44L This is a disadvantage in controlling losses.

  On the other hand, as in the present embodiment, it is advantageous to suppress the pressure loss by forming the straight pipe portion 43 to be short so that the second branch passage 44L is not curved from the right side to the left side. It is.

  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.

<< 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 above embodiment, the rotational axis of the bypass valve 41 is configured to extend in the direction in which the upstream ends of the first and second branch passages 44R and 44L are aligned in order to suppress the influence of flow separation. However, it is not limited to this configuration. For example, the rotational axis of the bypass valve 41 may extend in a direction orthogonal to both the arrangement direction of the upstream ends of the first and second branch passages 44R and 44L and the vertical direction, that is, the horizontal direction. Considering that the bypass valve 41 is fully opened at the time of natural intake, the bypass valve 41 opens symmetrically even if configured in this way. As a result, the influence of flow separation can be suppressed as in the above embodiment.

  In the above-described embodiment, the downstream end portion of the straight pipe portion 43 and the upstream end portions of the first and second branch passages 44R and 44L are both configured to define rectangular openings C1 to C3. However, it is not limited to this configuration.

  18A to 18C are diagrams corresponding to FIGS. 15A to 15C showing a first modification of the bypass passage. As shown in the drawings, the bypass passage 40 'is configured such that the first and second branch passages 44R' and 44L 'branch from the downstream end portion of the straight pipe portion 43', as in the above-described embodiment. ing.

  The inner wall surface of the downstream end portion of the straight pipe portion 43 ′ is formed in a circular shape in a cross-sectional view perpendicular to the gas flow direction (right direction). Specifically, as shown in FIG. 18A, the downstream end portion of the straight pipe portion 43 defines an oval opening C1 'extending in the front-rear direction.

  On the other hand, the inner wall surface (front wall surface) opposite to the second branch passage 44L ′ at the upstream end of the first branch passage 44R ′ has a semicircular shape in a cross-sectional view perpendicular to the gas flow direction. On the other hand, the inner wall surface (rear inner wall surface) on the second branch passage 44L ′ side is formed in a rectangular shape in the same sectional view. Specifically, as shown in FIG. 18B, the upstream end portion of the first branch passage 44R ′ defines an opening C2 ′ having a shape obtained by inverting the substantially D-shape back and forth when viewed from the left. doing.

  Similarly, an inner wall surface (an inner wall surface on the rear side) opposite to the first branch passage 44R ′ at the upstream end portion of the second branch passage 44L ′ is a semicircle in a cross-sectional view perpendicular to the gas flow direction. On the other hand, the inner wall surface (front inner wall surface) on the first branch passage 44R ′ side is formed in a rectangular shape in the same sectional view. Specifically, as shown in FIG. 18B, the upstream end of the second branch passage 44L 'defines a substantially D-shaped opening C3' when viewed from the left.

  Further, the inner wall surfaces downstream of the upstream end portions in the first and second branch passages 44R ′ and 44L ′ are both cross-sectional views perpendicular to the gas flow direction from the respective upstream end portions toward the downstream side. As shown in the openings C4 ′ and C5 ′ in FIG. 15C, the respective downstream end portions are formed so as to reach a circular shape in the same sectional view. . Note that the flow path cross-sectional areas of the first and second branch passages 44R 'and 44L' are formed to be minimum at the downstream end portion shown in FIG. 15C.

  If comprised in this way, each flow path is made smooth, taking the largest possible cross-sectional area from the downstream end part of straight pipe | tube part 43 'to the upstream end part of 1st and 2nd branch channel | path 44R', 44L '. Can be changed. Thereby, while distributing gas smoothly, it becomes possible to suppress channel resistance of each passage.

  Further, the shape of the entire bypass passage can be appropriately modified.

  19 is a diagram corresponding to FIG. 10 illustrating a second modification of the bypass passage, and FIG. 20 is a diagram corresponding to FIG. The bypass passage 40 ″ according to the second modification is formed as a tournament-type passage, similarly to the bypass passage 40 according to the above-described embodiment.

  Specifically, the bypass passage 40 ″ is configured to guide the gas flowing in from the first passage 33 in order from the upstream side along the gas flow direction from one side of the cylinder row direction to the other side (from the left side to the right side). The upstream shared passages 41a ", 42" -43 "and the first and second branch passages 44R" as upstream independent passages branched from the downstream ends of the upstream shared passages 41a ", 42" -43 " , 44L ″.

  Here, the downstream ends of the first and second branch passages 44R ″ and 44L ″ extend in the surge tank direction, respectively, and the upstream ends of the independent passages 39 as the downstream independent passages in the surge tank 38, respectively. It is connected to the part facing the part.

  The upstream shared passages 41a ″, 42 ″ to 43 ″ are connected to the branch portion 33d and include a bypass valve, and are connected to the right end of the valve body 41a ″ from the downstream end. A bent portion 42 "bent so as to be directed in the direction and a downstream end portion of the bent portion 42", extending in a direction from one side to the other side (right direction) in the cylinder row direction, and downstream A straight pipe portion 43 ″ as a branch passage portion formed so that the first and second branch passages 44R ″ and 44L ″ branch from the end portion is provided.

  The first and second branch passages 44R ″ and 44L ″ are respectively formed after the upstream end continuous from the downstream end of the straight pipe portion 43 ″ extends in the direction from one side to the other side in the cylinder row direction. The portion on the downstream side of the upstream end portion is formed to bend toward the surge tank.

  Therefore, during natural intake, the gas flowing into the bypass passage 40 "passes through each part constituting the passage 40" and reaches each cylinder 11. Specifically, the gas that has passed through the throttle valve 32 flows into the valve body 41a ″ 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. In addition, the gas that has passed through the valve body 41a "and has flowed into the bent portion 42" flows rightward and then flows rightward. Subsequently, as shown by an arrow A7 ″, the gas that has passed through the bent portion 42 ″ flows into the straight pipe portion 43 ″ and flows to the right. The gas that passes through the straight pipe portion 43 ″ passes from the left to the right. Oriented to head towards. Subsequently, as indicated by arrows A8 "and A9", one of the gases passing through the straight pipe portion 43 "flows through the front side, while flowing into the first branch passage 44R" flows through the rear side. The other flows into the second branch passage 44L ″.

  With this configuration, the downstream end portion of the straight pipe portion 43 ″ and the upstream end portions of the first and second branch passages 44R ″ and 44L ″ extend in the same direction. Similar to the embodiment, the gas can be evenly distributed to each cylinder 11 while the bypass passage 40 ″ is laid out in a compact layout.

  The bypass passage 40 ″ according to the second modified example has the same effect as that of the above embodiment, but is closer to the conventional bypass passage 1040 than the above embodiment from the viewpoint of the overall layout.

  That is, the first and second branch passages 44R ″ and 44L ″ according to the second modified example can be seen from the downstream end portion of the straight pipe portion 1043 related to the conventional bypass passage 1040, as can be seen by comparing FIG. 17 and FIG. The entire bent pipe portion 1044 can be divided into front and rear or left and right by a wall portion extending in the vertical direction.

  As a result, the layout around the surge tank 38 including the bypass passage 40 ″ can be diverted to the same layout as the conventional bypass passage 1040. This ensures the assembly performance of the entire intake passage 30. In addition, it is effective in reducing the size.

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 41a Valve body (upstream shared passage)
42 Folding part (upstream shared passage)
43 Straight pipe (upstream shared passage, branch passage)
44R First branch passage (upstream independent passage)
44L 2nd branch passage (upstream independent passage)
50 Exhaust passage 52 EGR passage

Claims (7)

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 provided with a branch passage portion that extends in a direction from one side to the other side in the cylinder row direction and is formed such that the plurality of upstream independent passages branch from the downstream end portion. And
Each of the plurality of upstream independent passages has an upstream end continuous from the downstream end of the branch passage extending in a direction from one side to the other side in the cylinder row direction, and then is more than the upstream end. An intake system for a multi-cylinder engine, wherein a downstream portion is formed to bend toward the surge tank. The intake device for a multi-cylinder engine according to claim 1,
The upstream end of the plurality of upstream independent passages is an intake device for a multi-cylinder engine arranged in a direction orthogonal to a direction from one side to the other side in the cylinder row direction. The intake device for a multi-cylinder engine according to claim 2,
The plurality of upstream independent passages are composed of first and second upstream independent passages,
While the inner wall surface of the downstream end portion of the upstream shared passage is formed in a circular shape in a cross-sectional view perpendicular to the gas flow direction,
An inner wall surface opposite to the second upstream independent passage at the upstream end of the first upstream independent passage is formed in a semicircular shape in a cross-sectional view perpendicular to the gas flow direction. On the other hand, the inner wall surface on the second upstream independent passage side is formed in a rectangular shape in the same sectional view,
The inner wall surface opposite to the first upstream independent passage at the upstream end of the second upstream independent passage is formed in a semicircular shape in a cross-sectional view perpendicular to the gas flow direction. On the other hand, the inner wall surface on the first upstream independent passage side is formed in a rectangular shape in the same sectional view,
The inner wall surfaces downstream of the upstream end portions in the first and second upstream side independent passages gradually from the upstream end portion toward the downstream side in a cross-sectional view perpendicular to the gas flow direction. The multi-cylinder engine intake device is deformed so as to approach a circular shape, and is formed so that each downstream end portion has a circular shape in the same sectional view. The multi-cylinder engine intake device according to claim 2 or 3,
The upstream shared passage has a bent portion that is bent so as to be directed in a direction from one side to the other side in the cylinder row direction, and a portion on the upstream side of the bent portion includes the plurality of An intake system for a multi-cylinder engine that extends in a direction orthogonal to an arrangement direction of upstream end portions of an upstream independent passage. The intake device for a multi-cylinder engine according to claim 4,
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;
A downstream end portion of the EGR passage is an intake device for a multi-cylinder engine connected to at least an upstream side of the bent portion in the intake passage. The multi-cylinder engine intake device according to claim 5,
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 device for a multi-cylinder engine according to claim 6,
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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