JP6544379B2 - Multi-cylinder engine intake system - Google Patents

Description

  The technology disclosed herein relates to a multi-cylinder engine intake system.

  Patent Document 1 discloses an intake system for an in-line three-cylinder engine having three cylinders arranged in a row and two intake ports for each cylinder as an example of an intake system of a multi-cylinder engine (intake manifold) Is disclosed. In this intake system, a total of six independent passages (dividing pipes) connected two by two for each of three cylinders, and the upstream ends of the six independent passages are arranged in a row according to the order in which the corresponding cylinders are arranged. A surge tank (collecting pipe) connected side by side, and two branch passages (branch pipes) each having a downstream end connected to the surge tank for introducing a gas to 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.

  The patent document 1 also discloses that two branch passages are connected at intervals in the cylinder row direction. Specifically, in the intake system disclosed in Patent Document 1, one of the two branch passages is connected to a portion facing the section from the first cylinder to the second cylinder, and two upstream sides are provided. 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 Application Laid-Open No. 10-068361

  By the way, when a tournament type intake passage as described in Patent Document 1 is used, a portion corresponding to the common passage before the branch is directed in the cylinder row direction 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 thus extended is branched into a plurality of branch passages immediately after being bent toward the surge tank, and each branched branch is connected to the surge tank at an interval in the cylinder row direction. It will be

  However, when configured in this manner, the inventors of the present invention can vary the amount of gas introduced between the branch passage connected to one side in the cylinder row direction and the branch passage connected to the other side. I noticed.

  That is, the gas flowing through the intake passage is directed from one side to the other side in the cylinder row direction when passing through the common passage. Then, of the plurality of branch passages, with respect to the branch passage positioned on the other side (for example, the front side of the engine) in the cylinder row direction, gas easily flows relatively, while the one side in the cylinder row direction For example, with regard to the branch passage located on the rear side of the engine, the gas can not flow more easily. Such a situation is undesirable for evenly distributing gas to each cylinder.

  Therefore, the common passage bent toward the surge tank is not branched immediately after being bent, but once it is orthogonal to the cylinder row direction and in the direction toward the surge tank (hereinafter, also referred to as “surge tank direction”) It is conceivable to branch into a plurality of branch paths after extending straight along. In this case, the gas flowing in the common passage flows along the wall surface that divides the portion extending in the surge tank direction, whereby the directivity from one side to the other side in the cylinder row direction is reduced, and the surge tank direction Will be directed to As a result, the gas can be evenly distributed to each branch passage, and hence to each cylinder, on one side and the other side in the cylinder row direction.

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

  The technology disclosed herein has been made in view of such a point, and the purpose thereof is to equalize the gas to each cylinder while compactly arranging the intake passage in the intake system of a multi-cylinder engine. To distribute to.

  The technology disclosed herein includes 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 connected to each of the plurality of intake ports. And an intake system for a multi-cylinder engine having a passage.

The intake passage includes a plurality of downstream independent passages respectively connected to the plurality of intake ports, and upstream ends of the plurality of downstream independent passages arranged in a row according to the order in which the corresponding cylinders are arranged. One surge tank connected in parallel, a plurality of upstream independent passages each having a downstream end connected to the surge tank and introducing a gas into the surge tank, and a plurality of upstream independent passages from the downstream end And the upstream shared passage from which the

The downstream ends of the plurality of upstream independent passages extend in a direction of a surge tank which is orthogonal to the cylinder row direction and which indicates a direction toward the surge tank, and make intervals in the cylinder row direction in the surge tank. The plurality of downstream independent passages are disposed at positions opposite to each other and connected to the upstream end of each of the plurality of downstream independent passages.

  The upstream shared passage is provided with a branch passage portion extending in a direction from one side to the other side in the cylinder row direction and formed to branch the plurality of upstream independent passages from the downstream end. The upstream end portions of the plurality of upstream independent passages extend from the one downstream side to the other side of the cylinder row direction, respectively, after the upstream end portion continuing from the downstream end portion of the branched passage portion extends A portion downstream of the end portion is formed to be curved toward the surge tank.

  According to this configuration, the gas flowing through the intake passage is directed from one side to the other side in the cylinder row direction when passing through the branch passage. Here, while the upstream ends of the respective upstream independent passages are continuous from the downstream end of the branch passage portion, the upstream ends are all directed from one side to the other side in the cylinder row direction. It extends. Then, the gas having the directivity as described above flows smoothly to each upstream end.

  For example, one of the upstream ends of the two upstream independent passages extends in the direction from one side to the other in the cylinder row direction, while the other extends in the direction orthogonal to the same direction. For example, the gas directed from one side to the other side in the cylinder row direction is likely to flow into the upstream end of the former as compared to the upstream end of the latter.

  On the other hand, according to the above configuration, the downstream end of the branch passage and the upstream end of each upstream independent passage extend in the same direction, so the directivity given when passing through the branch passage As a result, it is possible to avoid a situation in which more gas flows into the upstream end of any one of the upstream independent passages. Since the influence of directivity is suppressed, it is advantageous to evenly distribute the gas to each upstream independent passage, and hence to each cylinder.

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

  Thus, the intake passage distributes the gas to each upstream independent passage and reduces the directivity after distributing the gas so that the directivity provided in the branch passage portion is not affected. Is configured as.

  In addition, the above-described configuration allows the entire intake passage to be laid out compactly as compared with, for example, a configuration in which a passage extending in the surge tank direction is interposed between the upstream common passage and each upstream independent passage. .

  Thus, the gas can be evenly distributed to each cylinder while the intake passage is laid out compactly.

  Further, upstream ends 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 to uniformly distribute the gas having directivity given from one side to the other side in the cylinder row direction to the respective upstream independent passages.

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

  According to this configuration, the flow path is smoothly changed while the cross-sectional area is made as large as possible from the downstream end of the branch passage to the upstream end of the first and second upstream independent passages. Can. This makes it possible to distribute the gas smoothly and to suppress the flow passage resistance of each passage.

  The upstream shared passage has a bent portion that is bent so as to point 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 may be extended in a direction orthogonal to the alignment direction of the upstream ends of the upstream independent passages.

  According to this configuration, since the portion on the upstream side of the bent portion extends in the direction orthogonal to the direction in which the upstream ends of the upstream independent passages are aligned, at least the gas passing through this portion is It is not directed in that direction.

  If the directivity passing from one side to the other side is given to the gas passing through the upstream side of the bent portion, the gas is generated by each of the plurality of upstream independent passages. It becomes easy to flow in into the upstream end located in the other side of a row direction among the upstream end of the. Such a situation is undesirable for evenly distributing gas to each upstream independent passage and thus to each cylinder.

  On the other hand, according to the above configuration, the portion upstream of the bending portion is not provided with directivity in the line direction, which is advantageous in evenly distributing gas to each cylinder. become.

  Further, the multi-cylinder engine connects an exhaust passage through which the 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 corresponds to the intake passage. The downstream end portion of the EGR passage may be connected to the upstream side of at least the bent portion in the intake passage.

  According to this configuration, by connecting the downstream end of the EGR passage to at least the upstream side of the bending portion, the burned gas flowing into the intake passage from the EGR passage is the same as other gases such as fresh air The bent portion, the branch passage portion, and the upstream independent passage are sequentially passed. Thereby, the burnt gas can be equally distributed to each cylinder.

In addition, 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 provided on the upstream side of the surge tank. Is branched into a supercharging passage in which the machine is interposed, a plurality of upstream independent passages and the upstream common passage, and a bypass passage bypassing the supercharger, and the downstream end of the EGR passage The portion may be connected in the vicinity of a branch portion where the bypass passage in the intake passage branches .

  According to this configuration, burned gas can be introduced into both the supercharging passage and the bypass passage. Further, for example, the EGR passage can be laid out more compactly as compared with the configuration in which the downstream end of the EGR passage is separated upstream with respect to the branch portion.

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

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

  As described above, according to the intake system of the multi-cylinder engine, the gas can be evenly distributed to the cylinders while the intake passage is laid out compactly.

FIG. 1 is a schematic view illustrating the configuration of a multi-cylinder engine. FIG. 2 is a perspective view showing a configuration of a multi-cylinder engine with a part thereof omitted. FIG. 3 is a plan view schematically showing the configuration around four cylinders. FIG. 4 is a perspective view showing the entire configuration of the intake device as viewed from the front side. FIG. 5 is a perspective view showing the entire configuration of the intake device as viewed from the rear side. FIG. 6 is a cross-sectional view showing the passage structure on the turbocharger side. FIG. 7 is a longitudinal sectional view showing the passage structure on the turbocharger side. FIG. 8 is a perspective view showing a longitudinal cross section around the surge tank. FIG. 9 is a perspective view showing a vertical cross section different from FIG. FIG. 10 is a perspective view showing a 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 viewed from the front side. FIG. 12 is a view showing a passage structure related to the bypass passage as viewed from the rear side. FIG. 13 is a view showing a passage structure related to the bypass passage from above. FIG. 14 is a partially enlarged view of the bypass passage. FIG. 15A is a view showing a cross section of the bypass passage. FIG. 15B is a view showing a cross section different from FIG. 15A. FIG. 15C shows a cross section different from FIGS. 15A and 15B. FIG. 16 is a cross-sectional view showing a connection structure of 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 view corresponding to FIG. 15B showing 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 showing a second modification of the bypass passage. FIG. 20 is a view corresponding to FIG. 13 showing a second modification of the bypass passage.

  Hereinafter, an embodiment of a multi-cylinder engine intake system will be described in detail based on the drawings. The following description is an example. FIG. 1 is a diagram illustrating an engine 1 configured with an intake system of a multi-cylinder engine disclosed herein. Moreover, FIG. 2 is a perspective view which partially abbreviate | omits and shows the structure, and FIG. 3 is a top view which shows roughly the structure of four cylinders 11 periphery.

  The engine 1 is a gasoline engine (in particular, a four-stroke internal combustion engine) mounted on an FF type vehicle and, as shown in FIG. 1, has a mechanically driven supercharger (so-called supercharger) 34 It has composition.

  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 in the vehicle width direction. It is configured as a so-called in-line four-cylinder horizontal engine mounted in a posture. Thus, in the present embodiment, the longitudinal direction of the engine, which is the arrangement direction (cylinder row direction) of the four cylinders 11, substantially coincides with the vehicle width direction, and the transverse direction of the engine substantially coincides with the longitudinal direction .

  Hereinafter, unless otherwise specified, the front side means one side in the engine width direction (the front side in the vehicle longitudinal direction), the rear side the other side in the engine width direction (the rear side in the vehicle longitudinal direction), and the left side One side (left side in the vehicle width direction and the engine front side) of the direction (cylinder row direction) is the right side is the other side (right side in the vehicle width direction) of the engine longitudinal direction (cylinder row direction) Point to the rear).

  Further, in the following description, the upper side refers to the upper side in a state where the engine 1 is mounted on a 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 engine)
The engine 1 is configured to have a front intake air and a rear exhaust system. That is, as shown in FIG. 3, the engine 1 is disposed on the engine body 10 having four cylinders 11 (only one cylinder is shown in FIG. 1) and on the front side of the engine body 10 An intake passage 30 in communication with each cylinder 11 and an exhaust passage 50 disposed on the rear side of the engine body 10 and in communication with each cylinder 11 via an exhaust port 19 are provided.

  In the intake passage 30 according to the present embodiment, a plurality of passages for guiding gas, devices such as the turbocharger 34 and the intercooler 36, and a bypass passage 40 bypassing these devices are combined into a unitized intake Configure the device.

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

  Four cylinders 11 are formed in 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 central axes (hereinafter referred to as "cylinder axes") of the cylinders 11 extend parallel to one another and perpendicular to the cylinder row direction. Hereinafter, the four cylinders 11 shown in FIG. 3 may be referred to as No. 1 cylinder 11 A, No. 2 cylinder 11 B, No. 3 cylinder 11 C, and No. 4 cylinder 11 D sequentially 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 defines 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. The engine 1 is configured such that the ceiling surface of the combustion chamber 16 is lower than in the conventional case in order to increase the geometric compression ratio. The pent roof shape of the ceiling surface is almost flat.

  In the cylinder head 13, two intake ports 17 and 18 are formed for each cylinder 11. The two intake ports 17 and 18 communicate with the combustion chamber 16, and for each cylinder 11, 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 respectively open to the outer surface (mounting surface) 10 a of the engine body 10, and the downstream end of the intake passage 30 is connected. On the other hand, the downstream end of each of the ports 17 and 18 respectively opens to the ceiling surface of the combustion chamber 16.

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

  Also, the two intake ports 17, 18 include SCV ports configured such that, for each cylinder 11, the flow rate of the passing gas is throttled through a swirl control valve (SCV) 80. In the present embodiment, the second port 18 described above 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, as shown in FIG. 1, the intake valve operating mechanism has an intake electric motor VVT (Variable Valve Timing) 23 which is a variable valve operating mechanism. The intake electric motor VVT 23 is configured to continuously change the rotational phase of the intake camshaft within a predetermined angular range. As a result, the opening timing and 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 provided with two exhaust ports 19, 19 for each cylinder 11. The two exhaust ports 19 19 communicate with the combustion chamber 16 respectively.

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

  As shown in FIG. 1, the exhaust valve mechanism has an exhaust motor VVT (Variable Valve Timing) 24 which is a variable valve mechanism in this configuration example. The exhaust motor VVT 24 is configured to continuously change the rotational phase of the exhaust camshaft within a predetermined angular range. Thereby, the valve opening timing and the valve closing timing of the exhaust valve 22 change continuously. The exhaust valve mechanism may have a hydraulic VVT instead of the electric VVT.

  Although details will be 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 burnt 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 motor VVT 23 and the exhaust motor VVT 24 constitute an internal EGR system. The internal EGR system is not necessarily configured by VVT.

  An injector 6 is attached to the cylinder head 13 for each cylinder 11. The injector 6 is a multi-injection-type fuel injection valve in this configuration example, 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 passage 62 connecting 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 passage 62. The fuel pump 65 pumps fuel to the common rail 64. The fuel pump 65 is a plunger type pump driven by the crankshaft 15 in this configuration example. The common rail 64 is configured to store the fuel pumped by 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 from the injection port of the injector 6 into the combustion chamber 16.

  A spark plug 25 is attached to the cylinder head 13 for each cylinder 11. The spark plug 25 is attached in such a position that its tip is in the combustion chamber 16 and forcibly ignites the 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 of the engine body 10 and communicates with the intake ports 17 and 18 of the cylinders 11. The intake passage 30 is a passage through which the gas introduced into the combustion chamber 16 flows. An air cleaner 31 for filtering fresh air is disposed at the upstream end of the intake passage 30. In the vicinity of the downstream end of the intake passage 30, one surge tank 38 is disposed. As shown in FIG. 3, the intake passage 30 downstream of the surge tank 38 constitutes an independent passage 39 branched into two cylinders for each cylinder 11.

  Although details will be described later, one of the two independent paths 39 is connected to the first port 17 and the other is connected to the second port 18. Hereinafter, while the code “391” is given to the former independent passage 39, the code “392” may be given to the latter. Thus, the downstream end of the independent passage 39 is connected to the intake port 17, 18 of each cylinder 11. The independent passage 39 is an example of the “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 degree of opening thereof.

  A supercharger 34 is also disposed downstream of the throttle valve 32 in the intake passage 30. 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. The supercharger 34 according to the present embodiment is configured as a Roots-type supercharger, but this configuration may be any. For example, a Lysholm 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 34 a transmits the driving force between the supercharger 34 and the engine 1 and blocks the transmission of the driving force. When the control means (not shown) such as an ECU (Engine Control Unit) switches between disconnection and connection of the electromagnetic clutch 34a, the supercharger 34 is switched on and off. That is, the engine 1 switches between the operation of supercharging the gas introduced into the combustion chamber 16 and the 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 turbocharger 34 in the intake passage 30. The intercooler 36 is configured to cool the gas compressed in the turbocharger 34. The intercooler 36 in this configuration example is configured to be water-cooled.

  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 is a first passage for guiding the intake air cleaned by the air cleaner 31 to the turbocharger 34. 33, a second passage 35 for guiding the intake air compressed by the turbocharger 34 to the intercooler 36, and a third passage 37 for guiding the gas cooled by the intercooler 36 to the surge tank 38. The surge tank 38 is disposed in the vicinity of the inlets (upstream ends) 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 turbocharger 34 and the intercooler 36, constitute a "supercharging passage".

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

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

  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 turbocharger 34 in the intake passage 30 flows back through the bypass passage 40 upstream of the turbocharger 34. 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, a supercharging system is configured by the supercharger 34, the bypass passage 40, and the bypass valve 41.

  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 the exhaust gas discharged from the combustion chamber 16 flows. The upstream portion of the exhaust passage 50 constitutes an independent passage which branches for each cylinder 11, although detailed illustration is omitted. 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 is configured to include a three-way catalyst. The exhaust gas purification system is not limited to one including only the 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 recirculating a part of the burned gas to the intake passage 30. The upstream end of the EGR passage 52 is connected to the downstream of the catalytic converter 51 in the exhaust passage 50. The downstream end of the EGR passage 52 is connected upstream of the turbocharger 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 the burnt gas flowing through the EGR passage 52. By adjusting the opening degree of the EGR valve 54, it is possible to adjust the reflux amount of the cooled burned gas, that is, the external EGR gas.

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

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

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

  Each component constituting the intake passage 30 is disposed on the front side of the engine main body 10, specifically, on the front side of the mounting surface 10a described above. The mounting surface 10 a is configured by the outer surface on the front side of the cylinder head 13 and the cylinder block 12 as shown in FIGS. 6 to 7.

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

  As shown in FIGS. 2 and 4 to 8, the supercharger 34 is disposed opposite to the four cylinders 11 with the surge tank 38 interposed therebetween. Between the rear surface of the turbocharger 34 and the mounting surface 10a, a gap (space) corresponding to the size of the surge tank 38 is open. The first passage 33 extends in the cylinder row direction on the left side of the turbocharger 34 and is connected to the left end of the turbocharger 34. Moreover, the intercooler 36 is arrange | positioned downward with respect to the supercharger 34, and the supercharger 34 is arrange | positioned at predetermined intervals with respect to the attachment surface 10a similarly to the supercharger 34. As shown in FIG. The turbocharger 34 and the intercooler 36 are vertically adjacent to each other. The second passage 35 extends up and down so as to connect the front of the turbocharger 34 and the front of the intercooler 36. The surge tank 38 is disposed in a gap between the turbocharger 34 and the mounting surface 10 a, and a plurality of independent passages 39 are interposed between the non-cylinder end portions (inlets) of the intake ports 17 and 18. It is disposed opposite 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 10 a, and the intercooler 36 is positioned below the surge tank 38, The rear of the intercooler 36 and the bottom of the surge tank 38 are connected. The bypass passage 40 is formed to extend upward from the middle of the first passage 33 and to extend inward (rightward) of the engine body 10 and is connected to the upper portion of the surge tank 38. There is.

  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 and 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 short cylindrical shape made of metal, and as shown in FIGS. 4 to 6, in a posture in which the openings at both ends are directed to the left and right, it is positioned leftward and forward with respect to the mounting surface 10a. It is arranged to be. The 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 side) of the first passage 33 is connected to the downstream end (right end) of the throttle body 33a. A first passage main body 33b which is a portion is connected.

  The first passage main body 33b is configured to connect the throttle body 33a to the supercharger 34, as shown in FIG. Specifically, the first passage main body 33b is formed in a long cylindrical shape with the 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 to gradually increase in diameter from the outside in the cylinder row direction toward the inside (from the left side to the right side). While the downstream end of the throttle body 33a is connected to the upstream end (left end) of the first passage main body 33b as described above, the suction port of the turbocharger 34 is connected to the downstream end (right end) thereof. ing.

  Further, in the first passage main body 33b, a merging portion 33c where the EGR passage 52 merges is opened. 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. The merging portion 33 c is formed at least downstream of the throttle valve 32.

  Further, in the first passage main body 33b, a branched portion 33d branched to the bypass passage 40 is also opened. In the first passage body 33b, the branch portion 33d is formed on the top surface near the junction portion 33c (substantially the same position in the gas flow direction), and is connected to the upstream end of the bypass passage 40 (see FIG. See also 10). The branch portion 33d is connected to the supercharger 34, the intercooler 36, the four pairs of intake ports 17 and 18, and the respective intake ports 17 and 18 through independent passages 39, as shown in FIG. 10 and the like. It is located on the outer side (left side) in the cylinder row direction than the surge tank 38.

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

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

-Passageway structure on the turbocharger side-
First, the passage structure on the suction side of the turbocharger 34 will be described in detail.

  As described above, the turbocharger 34 according to the present embodiment is configured as a roots-type supercharger. Specifically, the supercharger 34 includes a pair of rotors (not shown) provided with a rotating shaft extending along the cylinder row direction, a casing 34b accommodating the rotor, and a drive pulley 34d for rotationally driving the rotor. The drive pulley 34d is connected to the crankshaft 15 via a drive belt (not shown) wound around the drive pulley 34d. The aforementioned electromagnetic clutch 34a is interposed between the drive pulley 34d and the rotor, and the driving force is transmitted to the turbocharger 34 via the crankshaft 15 by switching the electromagnetic clutch 34a off and on. Transmit and block transmission of driving force.

  The casing 34 b is formed in a cylindrical shape extending in the cylinder row direction, and divides the housing space of the rotor and the flow path of the gas passing through the turbocharger 34. More specifically, the casing 34b is formed in a cylindrical shape in which the left end and the front face are opened in the cylinder direction, and as shown in FIG. 6 etc., a predetermined center portion of the mounting surface 10a in the cylinder row direction is provided. It is arranged to be spaced apart and coaxial with the first passage 33.

  At the left end in the longitudinal direction of the casing 34b, a suction port for taking in the gas compressed by the rotor is opened, 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 34 c for discharging the gas compressed by the rotor is opened at the front of the casing 34 b (the side opposite to the engine body 10). The upstream end (upper end) of the second passage 35 is connected.

  The drive pulley 34d is configured to rotationally drive the rotor housed in the casing 34b. Specifically, the drive pulley 34d is formed in an axial shape that protrudes from the right end of the casing 34b and extends substantially coaxially with 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 drivingly connected to the supercharger 34 according to 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. In order to make the turbocharger 34 and the intercooler 36 vertically adjacent to each other, the second passage 35 according to the present embodiment is formed to extend along the vertical direction of the engine 1. Further, as shown in FIG. 7, the upper and lower ends of the second passage 35 are respectively opened rearward (toward the engine main body 10). Here, the upper opening 35a is connected to the front (specifically, the discharge port 34c) of the casing 34b, and the lower opening 35b is the front of the intercooler 36 (the front of the cooler housing 36c) )It is connected to the.

  Specifically, the second passage 35 extends in the vertical direction and is formed as a rectangular tube portion which is flat in the lateral direction, and the upper and lower end portions thereof are respectively bent rearward. That is, as shown in FIG. 7, the second passage 35 is configured to form a substantially U-shaped flow passage 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 36 a having a gas cooling function and the side of the core 36 a as shown in FIGS. 4 to 7. A core connection portion 36b and a cooler housing 36c for accommodating the core 36a are provided. Although details will be omitted, a water supply pipe for supplying cooling water to the core 36a and a drainage pipe for discharging the cooling water from the core 36a are connected to the core connection portion 36b.

  The core 36a is formed in a rectangular shape, and is supported in a posture in which one side surface (rear surface) and the mounting surface 10a face each other. The front surface of the core 36a constitutes the inflow surface of the gas, while the rear surface of the core 36a constitutes the outflow surface of the gas, which is the widest surface of the core 36a. Although not shown, a plurality of water tubes each having a flat cylindrical thin plate material are arranged in the core 36a, and corrugated corrugated fins are connected to the outer wall surfaces of the water tubes by brazing or the like. . With this configuration, the cooling water supplied from the water supply pipe is introduced into each water tube to cool the high-temperature gas. Cooling water warmed by cooling the gas is drained from each water tube through a drain. Further, by providing the corrugated fins, the surface area of each water tube is increased to improve the heat radiation effect.

  As shown in FIG. 4, the core connection 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 and the drainage pipe, and the water tube are mutually connected via the core connection portion 36b. The core connection portion 36 b constitutes a right side wall portion of the intercooler 36 and, together with the cooler housing 36 c, divides the housing space of the core 36 a.

  The cooler housing 36 c is disposed below the casing 34 b and defines a storage space of the core 36 a and is a flow interposed between the second passage 35 and the third passage 37 in the intake passage 30. It constitutes a road.

  Specifically, the cooler housing 36c is formed in the shape of a rectangular thin box in which the front surface and the rear surface are open, and is supported in a posture in which the rear surface and the mounting surface 10a face each other at the lower position of the casing 34b. There is. The rear surface is disposed at a predetermined distance (see FIG. 7) with respect to the mounting surface 10a of the engine body 10, similarly to the casing 34b.

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

  The third passage 37 is a member integrally formed with the surge tank 38 and the independent passage 39 and configured to connect the intercooler 36 to the surge tank 38 as shown in FIGS. 7 and 8. There is. More specifically, the third passage 37 is fastened to the cooler housing 36c sequentially from the upstream side, and the introduction portion 37a for collecting the gas having passed through the intercooler 36 and the introduction for introducing the gas collected in the collection portion 37a to the surge tank 38 And a portion 37b. The third passage 37 is disposed below the surge tank 38 at least in a vehicle mounted state.

  The collecting portion 37a is formed in the front side, that is, in the form of a shallow box having a depth in the front and rear, in which the cooler housing 36c side is open. The opening is an opening on the rear side of the cooler housing 36c as shown in FIG. Connected to 36e. The collecting portion 37 a is positioned in a gap between the rear surface of the cooler housing 36 c and the mounting surface 10 a of the engine body 10. Further, the upstream end of the introducing unit 37b is connected to the rear surface of the collecting unit 37a.

  The introduction portion 37b is formed as a curved pipe portion extending substantially in the vertical direction, and the upstream end thereof is connected to the rear surface of the collective portion 37a, while the downstream end thereof is the central portion of the bottom surface of the surge tank (FIG. 9) are connected. As shown in FIG. 7 and the like, the introduction portion 37b sews a gap between a region from the rear surface of the collecting portion 37a to the rear surface of the casing 34b of the turbocharger 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 introducing portion 37 b extends obliquely upward and to the right from the connecting portion with the collecting portion 37 a, while the downstream portion thereof extends from the connecting portion with the surge tank 38. It is formed to extend directly upward to the connection portion. As a result of this formation, the downstream end of the introducing 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 (see FIG. 7).

  The surge tank 38 is formed in a substantially cylindrical shape extending in the cylinder row direction and closing both ends in the same direction. As described above, the surge tank 38 is disposed opposite to the opposite end of the intake ports 17 and 18 with the plurality of independent passages 39 interposed therebetween (see FIG. 7). As described later, when the plurality of independent passages 39 are respectively formed in a short cylindrical shape, the surge tank 38 is located in the vicinity of the inlets (upstream ends) 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 part 37 b) is connected to the bottom of the surge tank 38. An inlet 38b having a substantially circular cross section is opened at a central portion (specifically, a central portion in the cylinder row direction) of the inner bottom surface 38a of the surge tank 38, and a downstream end of the inlet 37b is Is connected to the surge tank 38 via the inlet 38b.

  The inlet 38 b is larger in diameter than the intake ports 17 and 18.

  Furthermore, in the surge tank 38, the dimension from the inlet 38b to one end (end on the first cylinder 11A side) in the cylinder row direction and the dimension from the other end (end on the fourth cylinder 11D) are substantially equal. It has become. With such a configuration, it is possible to secure the distribution performance of the intake air, which is advantageous in reducing the inter-cylinder difference in the filling efficiency.

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

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

  Four sets of independent passages 39 are disposed to correspond to each of the four sets of intake ports 17 and 18, respectively, and integrally formed third passage 37, surge tank 38 and independent passages 39 are provided. When assembled in the engine body 10, each independent passage 39 and the corresponding intake ports 17, 18 constitute one passage.

  As described above, the independent passages 39 are composed of an independent passage 391 corresponding to the first port 17 and an independent passage 392 corresponding to the second port 18 in one 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, while the second The port 18 and the corresponding independent passage 392 constitute a single independent passage. In this way, eight independent paths are constructed.

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

  By the way, as described later, the downstream side 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 tank Connected to the top of 38. The branch passages 44R and 44L are examples of the "upstream independent passage".

  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 the outside of the surge tank 38. The parts 38c and 38d are provided.

  Then, one branch passage (hereinafter referred to as “first branch passage”) is provided to the first introduction portion 38c located on one side (right side) in the cylinder row direction of the two first and second introduction portions 38c and 38d. And the second introduction portion 38d located on the other side (left side) is connected to the downstream end of the other branch passage (hereinafter also referred to as “second branch passage”) 44L. The ends are connected (see also FIG. 13).

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

  As shown in FIG. 8, the first introduction portion 38c is disposed to face a portion near 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 to face a portion near 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" configured as described above.

  That is, at the time of supercharging, while the engine 1 is operating, the output from the crankshaft 15 is transmitted through 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 discharges it from the discharge port 34c. The exhaled gas flows into the second passage 35 disposed in front of the casing 34b.

  As shown by arrow A2 in FIG. 7, the gas discharged from the turbocharger 34 and flowing into the second passage 35 flows from the discharge port 34c of the turbocharger 34 toward the front, and then flows to the second passage 35. It flows downward along. The gas that has flowed downward flows downward toward the intercooler 36 after reaching the lower part of the second passage 35.

  Subsequently, as shown by 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 side, and flows from the front to the rear. 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 of the opening 36 e on the rear side of the cooler housing 36 c and flows into the third passage 37.

  Then, as shown by arrow A4 in FIG. 7, the gas flowing from the intercooler 36 into the third passage 37 flows obliquely upward to the right along the upstream portion of the introduction portion 37b after passing through the collecting portion 37a ( The section S1 in FIG. 8 is also referred to), and thereafter, the flow flows directly upward along the downstream side portion of the introducing portion 37b (also refer to section S2 in FIG. 8). As shown by the arrow A5 in the figure, the gas that has passed through the introduction portion 37b flows into the space substantially at the center in the cylinder row direction in the surge tank 38, is temporarily stored in the surge tank 38, and then becomes independent. It is supplied to each cylinder 11 through the passage 39.

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

  FIG. 10 is a perspective view showing the passage structure relating to the bypass passage 40 as viewed obliquely from the rear, FIG. 11 is a view showing it as viewed from the front, and FIG. 12 is shown as viewed from the rear It is a figure and FIG. 13 is a figure which sees it from an upper side. And FIG. 14 is a figure which expands and shows FIG. 13 partially. 15A to 15C are diagrams showing cross sections of the bypass passage 40. FIG. 16 is a cross-sectional view showing a connection structure of the surge tank 38 and the bypass passage 40. As shown in FIG.

  The bypass passage 40 is formed as a so-called tournament-type passage, and in order from the upstream side along the gas flow direction, the gas flowing from the first passage 33 is guided from one side to the other side in the cylinder row direction. Including the configured upstream shared passage 41a, 42 to 43, and first and second branched passages 44R and 44L as upstream independent passages branched from the downstream end of the upstream shared passage 41a and 42 to 43 It is configured. The “direction from one side to the other side in the cylinder row direction” refers to the 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 sequentially connected to the branch 33d from the upstream side along the gas flow direction, and the valve body 41a in which the bypass valve 41 is incorporated, and the downstream of the valve body 41a. A bent portion 42 which is continuous from the end and bent rightward and is continuous from the downstream end of the bent portion 42 and extends rightward and first and second branch passages from the downstream end A straight pipe portion 43 formed to branch 44R, 44L is provided. The straight pipe portion 43 is an example of the “branch passage portion”.

  Specifically, the valve body 41 a is formed in a short cylindrical shape, and as shown in FIGS. 10 to 12, the valve body 41 a is disposed with the openings at both ends up and down at the upper position of the first passage 33. There is. Further, similarly to the first passage 33, the valve body 41a is located forward of the portion near the left end of the mounting surface 10a. The upstream end (lower end) of the valve body 41a is connected to the branched portion 33d of the first passage 33, while the downstream end (upper 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 (up and down direction) orthogonal to the alignment direction (front and back direction) of the upstream end portions of the first and second branch passages 44R and 44L.

  Further, the bypass valve 41 incorporated 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 arranging direction (in this example, the front-rear direction in this example) of the upstream ends. That is, when the bypass valve 41 is opened, the gas passing through the valve body 41 a flows on both sides (in this example, left and right sides) across the bypass valve 41. At this time, as a result of the gas flow along the bypass valve 41 being separated at the end of the valve 41, different flows may occur on the front side and the back side of the bypass valve 41. However, in this configuration example, since the bypass valve 41 is opened symmetrically in the front-rear direction, even if different flows occur on the front side and the back side, the first and second branch passages 44R, The influence can be suppressed with respect to the alignment direction of the upstream ends of 44L.

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

  The straight pipe portion 43 extends in the left-right direction and is formed into a flat rectangular tube shape 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 is opened 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 widens in a substantially tapered shape as it goes from the upstream end to the downstream side. The downstream end of the straight pipe portion 43 opens toward the right, and as shown in FIG. 15A, divides the rectangular opening C1 in a horizontally long longitudinal dimension with respect to the vertical dimension. doing. On the other hand, the upstream end (left end) of the first and second branch passages 44R and 44L is branched from this downstream end.

  The straight pipe portion 43 is configured to be shorter than the conventional straight pipe portion 1043 (see FIG. 17). In the present embodiment, the downstream end of the straight pipe portion 43 is positioned at least to the left of the second introduction portion 38 d of the surge tank 38 in the cylinder row direction. More specifically, the downstream end of the straight pipe portion 43 extends near the left end of the surge tank 38 in the cylinder row direction when viewed in the cylinder axial direction.

  The first and second branch passages 44R and 44L respectively extend in the right direction at the upstream end continuing from the downstream end of the straight pipe portion 43, and then the portion downstream of the upstream end is in the surge tank direction It is formed to be curved towards. Here, the “surge tank direction” indicates a direction orthogonal to the cylinder row direction and directed to the surge tank 38. Further, the upstream end portions of the first and second branch passages 44R and 44L are aligned in the front-rear direction.

  Specifically, the upstream end portions of the first and second branch passages 44R and 44L are divided so as to divide the downstream end portion of the straight pipe portion 43 in the front-rear direction. As shown in FIG. 15B, the upstream ends of the first and second branch passages 44R and 44L are aligned in the front-rear direction in a state of being separated by wall portions extending in the vertical direction and the left-right direction. With this configuration, it is possible to suppress pressure loss occurring in the vicinity of the central portion in the front-rear direction in the portion continuing from the downstream end of the straight pipe portion 43 to the upstream end of the first and second branch passages 44R and 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 opens toward the left, and divides vertically long rectangular openings C2 and C3 whose dimensions in the front-rear direction are smaller than the dimensions in the vertical direction. 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 size of the width W1 of the opening C2 on the side of the first branch passage 44R is the same as the size of the width W2 of the opening C3 on the side of the second branch passage 44L.

  In addition, the first branch passage 44R is curved so as to extend diagonally downward and rearward after extending from the upstream end configured as described above diagonally to the right and rearward. On the other hand, the second branch passage 44L is bent at a substantially right angle to form a convex toward the right front in the cylinder axial direction view (when viewed from the viewpoint shown in FIGS. 13 to 14) from the upstream end thereof. It is curved so that it goes diagonally downward and back.

  As described above, the downstream end of the straight pipe portion 43 is positioned to the left of the second introduction portion 38 d 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 and 44L both extend in the direction of the aforementioned surge tank, and as shown in FIG. 14 and the like, a plurality of independent passages 391 in the surge tank 38, It is connected to the opposite site to each upstream end of 392. Further, as shown in FIG. 15C, the downstream end portions of the first and second branch passages 44R, 44L are connected at intervals in the cylinder row direction, and respectively define circular openings C4, C5. ing.

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

  At the time of natural intake, the gas flowing into the bypass passage 40 passes through each portion constituting the passage 40 and reaches the cylinders 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 opening / closing condition of the bypass valve 41.

  As shown by arrow A6 in FIG. 13 to FIG. 14, the gas that has passed through the valve body 41a and flowed into the bending portion 42 flows toward the upper right, and then flows to the right while slightly going backward. Flow.

  Subsequently, the gas having 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. 13 to 14. The gas passing through the straight pipe portion 43 is directed from the left to the right.

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

  Then, as indicated by an arrow A8 in FIG. 13 to FIG. 14, the gas flowing into the first branch passage 44R 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 (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 Do.

  On the other hand, as indicated by an arrow A9 in FIG. 13 to FIG. 14, the gas flowing into the second branch passage 44L flows toward the right according to the directivity given when passing through the straight pipe portion 43. Then, it is led to the downstream end along the outer (left side in this example) wall surface of 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 Do.

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

(About the difference in the amount of gas introduced between cylinders)
The engine 1 is provided with 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 converts the control signal corresponding to the calculated control amount into the electromagnetic waves of the injector 6, the spark plug 25, the intake electric VVT 23, the exhaust electric VVT 24, the fuel supply system 61, the throttle valve 32, the EGR valve 54, and the turbocharger 34. The engine 1 is operated by outputting to the clutch 34 a and the bypass valve 41.

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

  For example, in an operating area on a lower load side than the predetermined load (hereinafter referred to as “fuel efficiency area”), the engine 1 is operated by natural intake while an operating area on a higher load side than the predetermined load (hereinafter referred to as “supercharged In the region “), the gas introduced into each cylinder 11 is supercharged by driving the supercharger 34.

  In addition, the ECU closes the SCV 80 to promote the generation of swirl in the fuel consumption area. As a result, the flow rate of the gas passing through the first port 17 can be increased to facilitate the mixing of the gases. 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 secure the introduction amount of gas.

  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 includes a curved pipe portion 1042 for guiding the gas upward, and a straight pipe portion 1043 for guiding the gas having passed through the curved pipe portion 1042 to the right. And a bent pipe portion 1044 which is bent obliquely backward and guides the gas passing through the straight pipe portion 1043 backward, and branched into two branches from the downstream end of the bent pipe portion 1044 and connected to the surge tank 38 And the branched 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 inventors of the present application realized that there is a possibility that the introduction amount of gas may vary with the branch pipe portion 1045L to be connected.

  That is, the gas flowing through the bypass passage 1040 is directed from the left to the right in the cylinder row direction when passing through the straight pipe portion 1043. Then, of the plurality of branch pipe portions 1045R and 1045L, the branch pipe portion 1045R positioned on the right side in the cylinder row direction is relatively easy to flow gas, while the branch pipe portion 1045L positioned on the left side in the cylinder row direction As for the gas, it is more difficult for it to flow. Such a situation is undesirable for evenly distributing the gas to each cylinder 11.

  Therefore, it is conceivable to provide a passage extending in the surge tank direction 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 in the bypass passage 1040 flows along the wall surface of the passage extending in the surge tank direction, whereby the directivity from the left side to the right side in the cylinder row direction is reduced and directed to the surge tank direction. Become so. As a result, the gas can be evenly distributed to the branch pipe portions 1045R and 1045L and hence to the cylinders 11 on the right and left sides in the cylinder row direction.

  However, if a passage extending in the direction of the surge tank is provided in the middle of the bypass passage 1040, depending on the size of the passage, there is a risk that it will be difficult to lay out the intake passage compactly.

  On the other hand, in the present embodiment, the gas flowing through the bypass passage 40 is directed from one side to the other side in the cylinder row direction when passing through the straight pipe portion 43 as shown in FIGS. In this example, it is directed to the right). Here, from the downstream end of the straight pipe portion 43, the upstream ends of the first and second branch passages 44R and 44L are continuous, and the upstream ends are all from one side in the cylinder row direction. It extends in the direction towards the other side. Then, the gas having the directivity as described above flows smoothly to 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. For example, the gas directed from one side to the other side in the cylinder row direction is likely to flow into the upstream end of the former as compared to the upstream end of the latter.

  In the bypass passage 40, the downstream end of the straight pipe portion 43 and the upstream ends of the first and second branch passages 44R and 44L extend in the same direction, as shown in FIGS. Therefore, due to the directivity given when passing through the straight pipe portion 43, it is possible to avoid a situation in which more gas flows into the upstream end of one of the branch passages. Become. It is advantageous in evenly distributing the gas to the first and second branch passages 44R, 44L and hence to the cylinders 11 by the amount of suppressing the influence of directivity.

  Also, when the gas that has flowed into each of the first and second branch passages 44R and 44L passes a portion downstream of the upstream end of each of the first and second branch passages 44R and 44L, as shown by arrows A8 to A9 in FIGS. Flow 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 and distributes the gas so that the directivity given in the straight pipe portion 43 has no influence. It is later configured to reduce its directivity.

  In addition, the bypass passage 40 can have a compact layout of the entire intake passage 30 as compared with the passage extending in the direction of the surge tank in the middle of the bypass passage 40 'as described above.

  Further, the bypass passage 40 is, for example, compared to the configuration in which the downstream end of the straight pipe portion 43 and the upstream end of the first and second branch passages 44R and 44L are extended in different directions, respectively. The area around the branch portion (the portion where the first and second branch passages 44R and 44L branch from the straight pipe portion 43) can be made compact.

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

  Further, as shown in FIGS. 10 to 13, etc., the upstream end portions of the first and second branch passages 44R and 44L are arranged in a direction (front-rear direction) orthogonal to the cylinder row direction, so straight pipes When passing through the portion 43, it is advantageous in evenly distributing the gas to which directivity is given from one side to the other side in the cylinder row direction to each of the first and second branch passages 44R, 44L. become.

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

  That is, if directivity is given to the gas passing through the valve body 41a from the rear side to the front side in the arranging direction, the gas is transmitted to the first and second branch passages 44R and 44L. It becomes easy to flow in into the upstream end of the 1st branch passage 44R located in the front side of a row direction among the upstream ends. Such a situation is undesirable for evenly distributing the gas to each cylinder 11.

  On the other hand, although the valve body 41a according to this embodiment imparts directivity in the direction orthogonal to the alignment direction, it does not impart directivity in the alignment direction. This is advantageous in evenly distributing the gas.

  Further, as shown in FIG. 13 to FIG. 14 and the like, by connecting the downstream end of the EGR passage 52 to at least the upstream side of the bending portion 42, burned gas flowing into the bypass passage 40 from the EGR passage 52 Similarly to the other gases such as fresh air, the bent portion 42, the straight pipe portion 43, and the first and second branch passages 44R and 44L are sequentially passed. Thereby, the burnt gas can be equally distributed to the cylinders 11.

  Further, as shown in FIG. 13 and the like, since the merging portion 33c of the EGR passage 52 is disposed in the vicinity of the branch portion 33d in the intake passage 30, the supercharging passage (supercharger 34, second passage 35, inter Burned gas can be introduced into both the cooler 36 and the third passage 37) and the bypass passage 40. In addition, for example, the EGR passage 52 can be laid out in a compact layout as compared with a configuration in which the merging portion 33c is separated 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 in the vertical direction in the vehicle mounted state, and then opens at the central portion of the surge tank 38 in the cylinder row direction. It is connected to the surge tank 38 via the inlet 38b.

  According to this configuration, with regard to the bypass passage 40, the priority is given to the gas distribution performance as described above, while a layout simpler than the bypass passage 40 can be realized with respect to the supercharging passage.

  Further, as shown in FIGS. 10 and 14, since the bypass valve 41 is opened and closed by the rotation shaft extending in the direction in which the upstream ends of the first and second branch passages 44R and 44L are aligned, the bypass valve is Even if the gas passing through the valve 41 generates different flows on the front side and the back side of the valve 41, the influence can be suppressed with respect to the direction in which the upstream ends are aligned. This is effective in evenly distributing the gas to each of the first and second branch passages 44R, 44L.

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

  If a part of the second branch passage 44L is curved from the right to the left, the bending direction is opposite to the direction directed in the straight pipe portion 43, so the pressure in the second branch passage 44L It is disadvantageous to control the loss.

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

  Further, the engine 1 has a cylinder by providing a negative overlap period (hereinafter referred to as “NVO”) in which both the intake valve 21 and the exhaust valve 22 close with the exhaust top dead center in the above-described fuel consumption region. In addition to confining the internal EGR gas inside, setting the closing timing of the intake valve 21 during the compression stroke according to the setting of NVO (hereinafter referred to as “slow closing”) realizes a mirror cycle of the late closing method It is supposed to

  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 the internal EGR introduced into the cylinder 11 along with the rise of the piston 14 Gas will be blown back to the intake side.

  In the case of a four-cylinder engine, 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 left and right in the cylinder row direction. The gases 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, can be sufficiently diffused because there is only a place to go to the left or right of the cylinder row direction. I can not do it.

  Therefore, in the surge tank 38, the blown back gas tends to be stagnant in the space on both ends in the cylinder row direction, as compared with the space on the center side.

  Therefore, it is conceivable to flush the internal EGR gas accumulated on the end side by the fresh air introduced from the intake passage 30. In order to realize such a measure, it is required to uniformly introduce fresh air to each part of the surge tank 38.

  The above-described configuration is effective in satisfying such a requirement in that fresh air can be introduced in a well-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 illustrated about the in-line 4-cylinder engine, it is not restricted to this structure. For example, it may be an engine having at least three or more cylinders, such as an in-line three-cylinder engine or an in-line six-cylinder engine. Further, the number of passages branched as the upstream independent passages may be changed according to the number of cylinders.

  Further, in the above embodiment, the rotation shaft 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 arranged in order to suppress the influence of flow separation. However, it is not limited to this configuration. For example, the rotation axis of the bypass valve 41 may be extended in a direction perpendicular to both the direction in which the upstream ends of the first and second branch passages 44R and 44L are aligned and the vertical direction, that is, in the left-right direction. In consideration of making the bypass valve 41 fully open at the time of natural intake, the bypass valve 41 is opened symmetrically in the front-rear direction even if configured in this way. Thus, as in the above embodiment, the influence of flow separation can be suppressed.

  Further, in the above embodiment, the downstream end of the straight pipe portion 43 and the upstream end of the first and second branch passages 44R and 44L are both configured to partition the rectangular openings C1 to C3. Although this has been done, 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 figures, the bypass passage 40 'is configured such that the first and second branch passages 44R' and 44L 'branch from the downstream end of the straight pipe portion 43', as in the previous embodiment. ing.

  The inner wall surface of the downstream end 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 of the straight pipe portion 43 defines an oblong opening C1 'extending in the front-rear direction.

  The inner wall surface (inner wall surface on the front side) 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 (the inner wall surface on the rear side) on the side of the second branch passage 44L 'is formed in a rectangular shape in the same cross sectional view. Specifically, as shown in FIG. 18B, the upstream end of the first branch passage 44R ′ defines an opening C2 ′ having a shape in which the letter “D” is inverted back and forth as viewed from the left side. doing.

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

  Furthermore, the inner wall surfaces downstream of the upstream end in the first and second branch passages 44R ′ and 44L ′ both have a cross-sectional view perpendicular to the gas flow direction from the respective upstream end toward the downstream side. Are gradually deformed so as to approach a circular shape, and each downstream end is formed so as to reach a circular shape in the same sectional view as shown in openings C4 'and C5' in FIG. 15C. . The cross-sectional areas of the first and second branch passages 44R 'and 44L' are formed to be minimum at the downstream end shown in FIG. 15C.

  In this configuration, each flow path is smoothed while taking as large a cross-sectional area as possible from the downstream end of the straight pipe portion 43 'to the upstream end of the first and second branch passages 44R' and 44L '. Can be changed to This makes it possible to distribute the gas smoothly and to suppress the flow passage resistance of each passage.

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

  FIG. 19 is a view corresponding to FIG. 10 showing a second modified example of the bypass passage, and FIG. 20 is a view 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 from one side to the other side (left to right) sequentially from the upstream side along the gas flow direction First and second branch passages 44R "as upstream independent passages branched from the downstream ends of the upstream side shared passages 41a" and 42 "to 43" and the upstream side shared passages 41a "and 42" to 43 " , 44 L ".

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

  The upstream shared passage 41a ′ ′, 42 ′ ′-43 ′ ′ is connected to the branch 33d and is continuous with the valve body 41a ′ ′ containing the bypass valve and the downstream end of the valve body 41a ′ ′, A bent portion 42 ′ ′ bent in a direction-directed direction and a downstream end of the bent portion 42 ′ ′ continue from the one side to the other side in the cylinder row direction (right direction), and further downstream A straight pipe portion 43 ′ ′ is provided as a branch passage portion formed such that the first and second branch passages 44R ′ ′ and 44L ′ ′ branch from the end.

  The first and second branch passages 44R ′ ′ and 44L ′ ′ each have an upstream end portion continuing from the downstream end portion of the straight pipe portion 43 ′ ′ extending from one side to the other side in the cylinder row direction A portion downstream of the upstream end is formed to be curved toward the surge tank.

  Therefore, at the time of natural intake, the gas which has flowed into the bypass passage 40 ′ ′ passes through each portion constituting the passage 40 ′ ′ and reaches the cylinders 11. Specifically, 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 opening / closing condition of the bypass valve 41 as shown by arrow A 6 ′ ′ in FIG. The gas that has passed through the valve body 41 a ′ ′ and has flowed into the bent portion 42 ′ ′ flows toward the upper right, and then flows toward the right. Subsequently, the gas having passed through the bent portion 42 ′ ′ flows into the straight pipe portion 43 ′ ′ and flows to the right as shown by the arrow A7 ′ ′. The gas passing through the straight pipe portion 43 ′ ′ is from the left to the right You will be directed towards you. Subsequently, as shown by the arrows A8 ′ ′ and A9 ′ ′, one of the gases having passed through the straight pipe portion 43 ′ ′, which flows on the front side, flows into the first branch passage 44R ′ ′ while it flows on the rear side. The other flows into the second branch passage 44L ′ ′.

  In this configuration, the downstream end of the straight pipe portion 43 ′ ′ and the upstream end of the first and second branch passages 44R ′ ′ and 44L ′ ′ extend in the same direction, and the like, for various reasons. As in the embodiment, the gas can be evenly distributed to the cylinders 11 while the bypass passage 40 ′ ′ is compactly laid out.

  The bypass passage 40 ′ ′ according to the second modification has the same function and effect as those of the embodiment, but is closer to the conventional bypass passage 1040 than the embodiment from the viewpoint of the overall layout.

  That is, the first and second branch passages 44R ′ ′, 44L ′ ′ according to the second modification can be seen from the downstream end of the straight pipe portion 1043 according to the conventional bypass passage 1040, as can be seen by comparing FIGS. The whole of the bent tube portion 1044 can be configured by dividing the wall portion extending in the vertical direction into two in the front and rear or left and right.

  Thus, the layout similar to that of the conventional bypass passage 1040 can be diverted to parts around the surge tank 38 including the bypass passage 40 ′ ′. This ensures the assembly performance of the entire intake passage 30. In addition, it is effective in achieving the compactification.

1 Engine (multi-cylinder engine)
11 cylinders
17 First port (intake port)
18 2nd port (intake port)
30 intake passage 33c merging portion 33d branching portion 34 supercharger (supercharging passage)
35 second passage (supercharged passage)
36 Intercooler (supercharged aisle)
37 third aisle (supercharged aisle)
38 Surge tank 38b Inlet 39 Independent passage (downstream independent passage)
40 bypass passage 41a valve body (upstream common passage)
42 bend (upstream shared path)
43 Straight pipe (upstream common passage, branch passage)
44R 1st branch passage (upstream independent passage)
44L 2nd branch passage (upstream independent passage)
50 exhaust passage 52 EGR passage

Claims (7)

A plurality of cylinders including at least three or more cylinders arranged in a row, a plurality of intake ports respectively communicating with each of the plurality of cylinders, and an intake passage connected to each of the plurality of intake ports An intake system for a cylinder engine,
The intake passage is
A plurality of downstream independent passages respectively connected to each of the plurality of intake ports;
One upstream end of each of the plurality of downstream independent passages is connected in a row according to the order of the corresponding cylinders, and one surge tank;
A plurality of upstream independent passages, each having a downstream end connected to the surge tank for introducing a gas into the surge tank;
An upstream shared passage where the plurality of upstream independent passages branch from the downstream end;
The downstream ends of the plurality of upstream independent passages extend in a direction of a surge tank which is orthogonal to the cylinder row direction and which indicates a direction toward the surge tank, and make intervals in the cylinder row direction in the surge tank. Are disposed and connected to the opposite site to the upstream end of each of the plurality of downstream independent passages,
The upstream shared passage is provided with a branch passage portion which extends in a direction from one side to the other side in the cylinder row direction and is formed to branch the plurality of upstream independent passages from the downstream end portion Yes,
Each of the plurality of upstream independent passages has an upstream end continued from the downstream end of the branch passage extending from one side to the other side in the cylinder row direction, and then the upstream end. An intake system of a multi-cylinder engine, wherein a downstream portion is formed to be curved toward the surge tank. In the multi-cylinder engine intake system according to claim 1,
An intake system of a multi-cylinder engine, wherein upstream ends of the plurality of upstream independent passages are arranged in a direction orthogonal to a direction from one side to the other side in the cylinder row direction. In the multi-cylinder engine intake system according to claim 2,
The plurality of upstream independent passages are composed of first and second upstream independent passages,
The inner wall surface of the downstream end of the upstream shared passage is formed in a circular shape in a cross-sectional view perpendicular to the gas flow direction,
The 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 cross sectional view,
Both the inner wall surfaces of the first and second upstream independent passages on the downstream side from the upstream end gradually become smaller in a cross-sectional view perpendicular to the flow direction of the gas from the respective upstream ends toward the downstream side. An intake system of a multi-cylinder engine, which is deformed so as to approach a circular shape and is formed so as to reach a circular shape in the same cross sectional view at each downstream end. In the multi-cylinder engine intake system according to claim 2 or 3,
The upstream shared passage has a bent portion that is bent so as to point 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 of a multi-cylinder engine extending in a direction orthogonal to a direction in which upstream ends of the upstream independent passages are aligned. In the multi-cylinder engine intake system according to claim 4,
The multi-cylinder engine includes: an exhaust passage through which burned gas discharged from each of the plurality of cylinders flows;
And an EGR passage for connecting the exhaust passage and the intake passage and returning a portion of the burned gas to the intake passage.
An intake system of a multi-cylinder engine, wherein a downstream end of the EGR passage is connected to an upstream side of at least the bending portion in the intake passage. In the intake system of a multi-cylinder engine according to claim 5,
The multi-cylinder engine includes a supercharger disposed on the opposite side of the plurality of cylinders across the surge tank,
The intake passage is configured, on the upstream side of the surge tank, including a supercharging passage in which the supercharger is interposed, the plurality of upstream independent passages, and the upstream shared passage, Bifurcated into a bypass passage that bypasses the
An intake system of a multi-cylinder engine in which a downstream end of the EGR passage is connected in the vicinity of a branch portion where the bypass passage in the intake passage branches . In the multi-cylinder engine intake system according to claim 6,
The supercharging passage extends in the vertical direction in a vehicle mounted state, and then the intake of the multi-cylinder engine is connected to the surge tank via an inlet port opened at a central portion in the cylinder row direction of the surge tank. apparatus.

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