JP2019027393A - Engine intake passage structure - Google Patents

Abstract

To smoothly introduce gas to a combustion chamber in an engine with a flow control valve.SOLUTION: An intake passage 30 of an engine 1 comprises an upstream side passage 71, a downstream side passage 72 including a second port (suction port) 18, connected to the upstream side passage 71 via a surge tank 38, and connected to a combustion chamber 16 via the second port 18, and a swirl control valve 81 provided on the downstream side passage 72 and controlling fluidization of gas through opening degree adjustment of a valve body 81a. A downstream end of the upstream side passage 71 is constituted so that it is opposed to at least one part of the valve body 81a, when the valve body 81a is operated to open to a predetermined opening degree.SELECTED DRAWING: Figure 14

Description

  The technology disclosed herein relates to an intake passage structure of an engine.

  In Patent Document 1, as an example of an intake passage structure of an engine, a downstream passage (passage) communicating with a combustion chamber via an intake port and an upstream passage (intake pipe) connected to the upstream side of the downstream passage are disclosed. ) And a flow control valve provided on the way from the upstream side passage to the downstream side passage. This flow control valve is a so-called tumble control valve (hereinafter sometimes referred to as “TCV”), and can open to a predetermined opening to promote the generation of tumble.

JP 2012-219657 A

  By the way, in the engine as described in the said patent document 1, not a TCV but a swirl control valve (henceforth "SCV") may be provided as a flow control valve. In this case, generation of swirl can be promoted through adjustment of the opening degree of the SCV.

  In recent years, an engine equipped with such a flow control valve has been required to reduce pump loss from the viewpoint of improving thermal efficiency, for example. In order to reduce the pump loss, it is required to smoothly guide the gas reaching the combustion chamber through various passages.

  As a result of intensive studies, the inventors of the present application have found that there is room for improvement in guiding the gas to the combustion chamber regarding the configuration and layout of the flow control valves such as TCV and SCV.

  The technology disclosed herein has been made in view of such a point, and an object thereof is to smoothly guide gas to a combustion chamber in an intake passage structure of an engine provided with a flow control valve.

  The technology disclosed herein includes an intake passage connected to a combustion chamber, and the intake passage includes an upstream passage and an intake port, and the upstream passage is connected via a relay portion. On the other hand, a flow control valve that is provided in the downstream side passage connected to the combustion chamber via the intake port and the downstream side passage and controls the flow of the gas through the opening degree adjustment of the valve body And an intake passage structure for an engine.

  The downstream end portion of the upstream passage is configured to face at least a part of the valve body when the valve body is opened to a predetermined opening degree.

  Here, the flow control valve may be a so-called butterfly valve having a disc-like valve body, for example, a swirl control valve for promoting the generation of swirl, or for promoting the generation of tumble. It may be a tumble control valve.

  According to the above configuration, the gas flowing out from the downstream end portion of the upstream passage reaches the combustion chamber via the relay portion and the downstream passage. Here, the relay unit may be a surge tank, for example.

  For example, when the operating state of the engine is in a predetermined operating region, the valve body of the flow control valve opens to a predetermined opening. At that time, at least a part of the valve body faces the downstream end of the upstream passage.

  That is, for example, when the downstream end of the upstream passage and the upstream end of the downstream passage do not face each other, the gas flowing out of the upstream passage does not flow smoothly into the downstream passage, and the upstream end thereof It will collide with the wall near. This is inconvenient for guiding the gas smoothly.

  On the other hand, according to the above configuration, the gas flowing out from the upstream passage collides with a valve body configured to face the downstream end portion thereof. The valve body is provided in the downstream passage, the downstream passage is opened with the opening operation of the valve body, and the downstream passage has a relatively negative pressure in the intake stroke. Considering this, the gas colliding with the valve body flows smoothly through the opened downstream passage. As a result, the gas can be smoothly guided to the combustion chamber.

  The downstream end of the upstream passage may be connected to the relay unit at a predetermined angle with respect to the upstream end of the downstream passage.

  In this case, although the downstream end of the upstream passage and the upstream end of the downstream end passage do not face each other, according to the above configuration, the gas flowing out from the upstream passage is still in such a case. Is guided to the downstream passage through a valve body facing the downstream end of the upstream passage. This is advantageous for smoothly guiding the gas to the combustion chamber.

  When the valve body is opened to the predetermined opening, at least a part of the valve body protrudes from the downstream passage and enters the relay portion, and the downstream end portion of the upstream passage is The valve body may be configured to face a portion protruding from the downstream side passage.

  According to this configuration, the gas flowing out from the upstream passage flows into the downstream passage through the valve body protruding from the downstream passage without reaching the downstream passage. This is advantageous in determining the layout of the entire intake passage in that the gas can be smoothly guided to the combustion chamber while maintaining the degree of freedom of the relative positional relationship between the upstream passage and the downstream passage. Become.

  Further, if a relay portion is interposed between the upstream side passage and the downstream side passage, depending on the shape and layout of the relay portion, there is a possibility that it may be disadvantageous in guiding the gas to the combustion chamber.

  However, according to the above configuration, a part of the valve body protrudes from the downstream passage and enters the relay portion. Since this portion faces the downstream end of the upstream passage, it is advantageous for smoothly guiding the gas to the combustion chamber.

  The engine further includes an intake valve that is provided in the intake port and configured to open and close an intake port that is open to a ceiling surface of the combustion chamber, and the intake valve is a shaft portion that reciprocates up and down. And an umbrella portion connected to the lower end portion of the shaft portion and configured to close the intake port by coming into contact with the intake port from the inner side of the combustion chamber. The downstream end portion of the port is the umbrella back of a portion of the umbrella portion that is located closer to the cylinder shaft than the shaft portion in a cross-sectional view perpendicular to the engine output shaft when the intake valve opens the intake port. And the flow control valve is configured to actuate the valve body by a valve shaft extending in the engine output shaft direction, and extending to direct between the ceiling surface facing the back of the umbrella, The inner wall surface of the downstream passage in the cylinder axis direction When the valve body is opened to the predetermined opening degree in two minutes, one side close to the combustion chamber and the other side separated from the combustion chamber, the upstream side along the gas flow direction It is good also as extending toward the inner wall surface of the said other side in the said downstream channel | path as it goes downstream.

  According to this configuration, the intake port has a tumble port shape. When the intake valve opens the intake port, the downstream end of the intake port is directed between the umbrella back of the portion of the intake valve located inside the combustion chamber and the ceiling surface facing the umbrella back. It extends like so. Therefore, the intake air flowing in from the intake port is guided to flow between the umbrella back and the ceiling surface. The intake air thus guided flows from the cylinder inner surface on the opposite side of the intake valve across the cylinder shaft toward the lower side in the vertical direction (cylinder axis direction) and then toward the intake valve in the vertical direction. Flows upward. Thus, the intake air flowing into the combustion chamber generates a swirling flow around the central axis parallel to the engine output shaft. Therefore, the strength of the tumble flow is increased in the combustion chamber.

  Here, in order to further increase the strength of the tumble flow, it is required to increase the flow of the gas in the vertical direction. As a measure for this, it is conceivable that gas flows along the inner wall surface on the other side spaced apart from the combustion chamber in the cylinder axial direction in the downstream passage including the intake port. With this configuration, it is possible to increase the flow in the vertical direction by the distance from the combustion chamber as compared with the case where gas flows along the inner wall surface on one side close to the combustion chamber in the cylinder axial direction. become.

  Therefore, according to the above configuration, when the valve body is opened to a predetermined opening degree, the inner wall surface on the other side in the downstream passage as it goes from the upstream side to the downstream side along the gas flow direction. Extends to be oriented. If comprised in this way, the gas which flows along a valve body will flow toward the inner wall surface of the other side mentioned above, and will flow along the inner wall surface of the other side. Thereby, the strength of the tumble flow can be further increased.

  The engine has a plurality of cylinders arranged in a row, and is provided in the engine body configured to perform combustion according to a predetermined combustion order in each of the plurality of cylinders, A plurality of intake ports communicating with each of the plurality of cylinders, a plurality of intake valves that open and close each of the plurality of intake ports, and a variable valve mechanism that changes opening and closing timings of the plurality of intake valves. The variable valve mechanism is configured to set the closing timing of the plurality of intake valves during a compression stroke when the operating state of the engine body is in a predetermined operating region, and the downstream passage Each of the plurality of intake ports and a plurality of independent passages connected to each of the plurality of intake ports, and the relay portion is provided at the end of the plurality of intake ports on the non-cylinder side. And configured as a surge tank that is arranged opposite to the opposite side across the plurality of independent passages, and in which the upstream ends of the plurality of independent passages are connected in a line according to the order in which the corresponding cylinders are arranged. The upstream side passage is connected to the surge tank at the downstream end thereof, and is configured to introduce gas into the surge tank. When two cylinders adjacent to each other in the cylinder row direction are referred to as a first cylinder and a second cylinder in the order in which combustion occurs, the connection point between the downstream end of the upstream passage and the surge tank is the plurality of cylinders in the cylinder row direction. Of the independent passage is set to face the section from the upstream end portion of the independent passage corresponding to the preceding cylinder to the upstream end portion of the independent passage corresponding to the succeeding cylinder, and the upstream passage is The gas flowing through the upstream passage, of said subsequent cylinder and the starting cylinder is formed so as to direct the rear onset cylinder closer may be.

  According to this configuration, the engine is a multi-cylinder engine having a plurality of cylinders, and closes the intake valve during the compression stroke in a predetermined operation region. When such slow closing is performed, when the piston rises in the compression stroke, the gas side charged in the cylinder blows back to the intake side.

  Moreover, according to the said structure, the surge tank is arrange | positioned so as to oppose the intake port across each independent passage. With such an arrangement, the surge tank can be brought close to the intake port, and the flow path length (runner length) from the surge tank to the intake port can be shortened. By shortening the runner length, the entire engine can be laid out compactly, the volume of the intake passage can be reduced, and as a result, the response to intake can be improved.

  By the way, in an engine with a short runner length, if the above-described slow closing is executed, the gas blown back to the intake side may flow back to the surge tank via the intake port.

  In particular, in a four-cylinder engine, when the gas is blown back from the preceding cylinder during the compression stroke, the inside of the succeeding cylinder during the intake stroke becomes negative pressure, so the starting cylinder and the succeeding cylinder are adjacent in the cylinder row direction. In view of this, the gas that has flowed back from the preceding cylinder to the surge tank may be sucked into the subsequent function.

  Here, depending on the connection point between the upstream passage and the surge tank, the gas blown back from the preceding cylinder is swept away by the gas flowing in from the upstream passage, and as a result, more gas than is necessary for the succeeding cylinder is generated. There is a possibility that pre-ignition (hereinafter, also referred to as “play”) may occur.

  On the other hand, according to the above configuration, the upstream passage and the surge tank are connected at the upstream end of the independent passage leading to the succeeding cylinder from the upstream end of the independent passage leading to the preceding cylinder in the cylinder row direction. It is set within the interval between. With this setting, when the succeeding cylinder is in the intake stroke (that is, when the vicinity of the upstream end corresponding to the succeeding cylinder has a negative pressure), the gas flowing from the upstream passage into the surge tank Coupled with the direction toward the later cylinder, a flow toward the later cylinder is formed without joining the gas blown back from the earlier cylinder.

  Thus, for example, a configuration in which the connection portion between the upstream passage and the surge tank, the upstream end portion of the independent passage leading to the preceding cylinder, and the upstream end portion of the independent passage leading to the succeeding cylinder are arranged in this order in the cylinder row direction. As compared with, for the gas blown back from the starting cylinder, the gas flowing in from the upstream passage is less likely to become “tailing wind”. As a result, it is possible to suppress the intake of the gas blown back from the preceding cylinder into the subsequent cylinder, thereby suppressing the occurrence of pre-ignition.

  Moreover, if the connection point between the upstream passage and the surge tank is set as described above, for example, the upstream end of the independent passage corresponding to the preceding cylinder, the upstream end of the independent passage corresponding to the subsequent cylinder, and the upstream side Compared with the configuration in which the passage and surge tank connection points are arranged in this order in the cylinder row direction, the difference between cylinders such as filling efficiency is reduced, and the responsiveness is comparable between the starting cylinder and the succeeding cylinder Can be secured.

  As described above, according to the above-described configuration, it is possible to suppress the occurrence of plague due to gas blowback while ensuring the responsiveness of each cylinder.

  As described above, according to the intake passage structure of the engine, gas can be smoothly guided to the combustion chamber.

FIG. 1 is a schematic view illustrating the configuration of an engine. FIG. 2 is a perspective view showing the configuration of the engine with a part omitted. FIG. 3 is a plan view schematically showing a configuration around four cylinders. FIG. 4 is a perspective view showing the overall configuration of the intake device as viewed from the front side. FIG. 5 is a perspective view showing the overall configuration of the intake device as seen from the rear side. FIG. 6 is a cross-sectional view showing a passage structure on the supercharger side. FIG. 7 is a longitudinal sectional view showing a passage structure on the supercharger side. FIG. 8 is a perspective view showing a longitudinal section around the surge tank. FIG. 9 is a perspective view showing a vertical section different from FIG. FIG. 10 is a view showing the passage structure on the bypass passage side as viewed from above. FIG. 11 is a longitudinal sectional view showing a connection structure between the surge tank and the bypass passage. FIG. 12 is a cross-sectional view showing the passage structure from the bypass passage to the combustion chamber via the surge tank, together with the SCV in the closed state. FIG. 13 is a diagram for explaining an intake port structure having a tumble port shape and a structure of a combustion chamber. FIG. 14 is a cross-sectional view showing the passage structure from the bypass passage to the combustion chamber through the surge tank, together with the SCV in the open state. FIG. 15 is a view showing the passage structure from the bypass passage to the combustion chamber via the surge tank as viewed from above. FIG. 16 is a view showing the passage structure from the bypass passage to the combustion chamber via the surge tank as seen from the rear side.

  Hereinafter, an embodiment of an intake passage structure of an engine will be described in detail based on the drawings. In addition, the following description is an illustration. FIG. 1 is a schematic view illustrating an engine 1 to which an engine intake passage structure disclosed herein is applied. FIG. 2 is a perspective view in which a part of the configuration of the engine 1 is omitted, and FIG. 3 is a plan view schematically showing the configuration around the four cylinders 11.

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

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

  Hereinafter, unless otherwise specified, the front side refers to one side in the engine width direction (front side in the vehicle front-rear direction), the rear side refers to the other side in the engine width direction (rear side in the vehicle front-rear direction), and the left side refers to This refers to one side of the engine longitudinal direction (cylinder row direction) (the left side in the vehicle width direction and the engine front side), and the right side refers to the other side of the engine longitudinal direction (cylinder row direction) (the right side in the vehicle width direction). And the engine rear side).

  Further, in the following description, the upper side refers to the upper side in the vehicle height direction when the engine 1 is mounted on the vehicle (hereinafter also referred to as “vehicle mounted state”), and the lower side refers to the vehicle height direction in the vehicle mounted state. Point to the bottom.

(Schematic configuration of the engine)
In this configuration example, the engine 1 is configured as a front intake rear exhaust type. That is, as shown in FIG. 3, the engine 1 includes an engine main body 10 having four cylinders 11, and an intake passage 30 that is disposed on the front side of the engine main body 10 and communicates with each cylinder 11 via the intake ports 17 and 18. And an exhaust passage 50 that is disposed on the rear side of the engine body 10 and communicates with each cylinder 11 via exhaust ports 19 and 19. In FIG. 1, only one cylinder 11 is shown.

  In this configuration example, the intake passage 30 includes a plurality of passages for guiding gas, devices such as a supercharger 34 and an intercooler 36, and an air bypass passage that bypasses these devices (hereinafter simply referred to as “bypass passage”). 40 constitutes a unitized intake device.

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

  The aforementioned 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 the central axes (hereinafter referred to as “cylinder axes”) of the cylinders 11 extend in parallel to each other and extend perpendicular to the cylinder row direction. Hereinafter, the four cylinders 11 shown in FIG. 3 may be referred to as the first cylinder 11A, the second cylinder 11B, the third cylinder 11C, and the fourth cylinder 11D in order from the right side along the cylinder row direction.

  A piston 14 is slidably inserted into each cylinder 11. The piston 14 is connected to the crankshaft 15 via a connecting rod 141. The piston 14 divides the combustion chamber 16 together with the cylinder 11 and the cylinder head 13. The ceiling surface 90 of the combustion chamber 16 has a so-called pent roof shape (details will be described later). The “combustion chamber” here is not limited to the meaning of the space formed when the piston 14 reaches compression top dead center. The term “combustion chamber” is used in a broad sense.

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

  The upstream end of each intake port 17, 18 is opened to an outer surface (a front outer surface, hereinafter also referred to as “mounting surface”) 10 a on one side of the engine body 10, and a duct constituting the intake passage 30. Is connected at the downstream end. On the other hand, the downstream end of each intake port 17, 18 opens to the ceiling surface 90 of the combustion chamber 16.

  Hereinafter, “17A” instead of “17” is attached to the first port leading to the first cylinder 11A, and “18A” is attached instead of “18” to the second port leading to the cylinder 11A. There is. The same applies to the second cylinder 11B to the fourth cylinder 11D. For example, “18C” may be attached to the second port leading to the third cylinder 11C instead of “18”.

  The two intake ports 17 and 18 have a so-called tumble port shape, and are configured such that the gas flowing into the combustion chamber 16 generates a tumble flow in the combustion chamber 16. This configuration will be described later.

  Further, the two intake ports 17 and 18 include SCV ports configured so that the flow rate of the gas passing through each cylinder 11 is throttled via a swirl control valve (SCV) 81. In the present embodiment, the aforementioned second port 18 is configured as an SCV port. The SCV 81 constitutes a flow control device 80 for controlling the flow of gas (see FIG. 7).

  That is, the intake ports 17 and 18 according to this configuration example have a shape that promotes the generation of the tumble flow, and is configured to control the generation of the swirl flow via the SCV 81.

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

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

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

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

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

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

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

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

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

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

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

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

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

  An electromagnetic clutch 34 a is interposed between the supercharger 34 and the engine body 10. The electromagnetic clutch 34a transmits driving force between the supercharger 34 and the engine 1 or interrupts transmission of driving force. As will be described later, when a control unit (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 an operation of supercharging the gas introduced into the combustion chamber 16 and an operation of not supercharging the gas introduced into the combustion chamber 16 by switching the supercharger 34 on and off. It is configured to be able to.

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

  Further, as a passage connecting various devices incorporated in the intake passage 30, the intake passage 30 is disposed downstream of the air cleaner 31, and a first passage that guides the gas purified by the air cleaner 31 to the supercharger 34. 33, a second passage 35 that guides the gas compressed by the supercharger 34 to the intercooler 36, and a third passage 37 that guides the gas cooled by the intercooler 36 to the surge tank 38. The surge tank 38 is disposed near the inlet (upstream end) of the intake ports 17 and 18 in order to shorten the flow path length (runner length) from the surge tank 38 to the intake ports 17 and 18. The surge tank 38 exemplifies a “relay unit” in that it is interposed between an upstream passage 71 and a downstream passage 72, which will be described later, and relays the gas flow. The second passage 35 and the third passage 37 together with the supercharger 34 and the intercooler 36 constitute a “supercharging passage”.

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

  When the supercharger 34 is turned off (that is, when the electromagnetic clutch 34a is disconnected), the bypass valve 41 is fully opened. As a result, the gas flowing through the intake passage 30 bypasses the supercharger 34 and flows into the surge tank 38 and is introduced into the combustion chamber 16 via the independent passage 39. The engine 1 is operated by non-supercharging, that is, by 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 supercharger 34 in the intake passage 30 flows back upstream of the supercharger 34 through the bypass passage 40. Since the reverse flow rate can be adjusted by adjusting the opening degree of the bypass valve 41, the supercharging pressure of the gas introduced into the combustion chamber 16 can be adjusted. In this configuration example, the supercharger 34, the bypass passage 40, and the bypass valve 41 constitute a supercharging system.

  The exhaust passage 50 is connected to the rear outer surface of the engine body 10 and communicates with the exhaust port 19 of each cylinder 11. The exhaust passage 50 is a passage through which exhaust gas discharged from the combustion chamber 16 flows. Although the detailed illustration is omitted, the upstream portion of the exhaust passage 50 constitutes an independent passage branched for each cylinder 11. The upstream ends of these independent passages are connected to the exhaust port 19 of each cylinder 11. An exhaust gas purification system having one or more catalytic converters 51 is disposed in the exhaust passage 50. The catalytic converter 51 includes a three-way catalyst. Note that the exhaust gas purification system is not limited to the 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 returning a part of the burned gas to the intake passage 30. The upstream end of the EGR passage 52 is connected downstream of the catalytic converter 51 in the exhaust passage 50. The downstream end of the EGR passage 52 is connected to the intake passage 30 upstream of the supercharger 34 and downstream of the throttle valve 32.

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

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

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

  4 is a perspective view showing the entire configuration of the unitized intake passage 30 as seen from the front side, and FIG. 5 is a perspective view showing the overall configuration of the intake passage 30 as seen from the rear side. 6 is a transverse sectional view showing a passage structure on the supercharger 34 side in 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 a vertical cross section different from FIG.

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

  As described above, the intake passage 30 includes a plurality of passages for guiding gas (specifically, the first passage 33, the second passage 35, the third passage 37, the surge tank 38, and the independent passage 39), the supercharger 34, the intercooler 36, and the like, and a bypass passage 40 that bypasses these devices are combined.

  First, a schematic layout of these components will be described.

  As shown in FIG. 2 and FIGS. 4 to 8, the supercharger 34 is disposed opposite to the four cylinders 11 across the surge tank 38. A gap corresponding to the dimension of the surge tank 38 is provided between the rear surface of the supercharger 34 and the mounting surface 10a. The first passage 33 extends along the cylinder row direction on the left side of the supercharger 34 and is connected to the left end of the supercharger 34. The supercharger 34 and the intercooler 36 are arranged vertically in this order and are adjacent to each other in the same direction. The second passage 35 extends vertically so as to connect the front part of the supercharger 34 and the front part of the intercooler 36. The surge tank 38 is disposed in the gap between the supercharger 34 and the mounting surface 10a, and is opposed to the upstream end of the intake ports 17 and 18 on the opposite side across the plurality of independent passages 39. Are arranged. The third passage 37 extends so as to sew a gap between the intercooler 36 and the supercharger 34 and the mounting surface 10a, and connects the rear portion of the intercooler 36 and the bottom portion of the surge tank 38. Yes. The bypass passage 40 is formed so as to branch from the middle of the first passage 33 and extend upward, and then to extend inward (rightward) of the engine body 10, and is branched into two branches on the downstream side. It is connected to the upper part of the surge tank 38 above.

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

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

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

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

  In addition, a branch portion (not shown) that branches to the bypass passage 40 is also opened in the first passage body 33b. This branch portion is formed on the upper surface of the first passage body 33b in the vicinity of the merging portion 33c (substantially the same position with respect to the gas flow direction), and an upstream end portion (a valve body 41a described later) of the bypass passage 40. ) Are connected (see also FIGS. 4 to 5). The upstream end of the bypass passage 40 has an independent passage 39 for the supercharger 34, the intercooler 36, the four sets of intake ports 17, 18 and the intake ports 17, 18 as shown in FIG. It is located on the outer side (left side) in the cylinder row direction with respect to the surge tank 38 connected thereto.

  Therefore, the fresh air purified by the air cleaner 31 and flowing into the first passage 33 passes through the throttle valve 32 and then merges with the external EGR gas flowing in from the merging portion 33c. And the gas which the fresh air and the external EGR gas merged flows into the bypass passage 40 via the aforementioned branching part at the time of natural intake, while at the time of supercharging, it merges with the gas which flows back through the bypass passage 40, The supercharger 34 is sucked from the downstream end of the first passage main body 33b (see arrow A1 in FIG. 6).

  Hereinafter, the passage structure on the supercharger 34 side, the passage structure on the bypass passage 40 side, and the structure of the intake ports 17 and 18 closely related to each passage structure will be described in order.

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

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

  The casing 34b is formed in a cylindrical shape extending in the cylinder row direction, and divides the housing space of the rotor and the gas flow path passing through the supercharger 34. Specifically, the casing 34b is formed in a substantially cylindrical shape extending in the cylinder row direction and having an opening at the left end and the front surface. As shown in FIG. 6 and the like, the casing 34b has a substantially central portion in the cylinder row direction. The first passage 33 and the first passage 33 are arranged so as to have a predetermined interval.

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

  The drive pulley 34d is configured to rotationally drive the rotor accommodated in the casing 34b. Specifically, the drive pulley 34d is formed in a shaft shape that protrudes from the right end of the casing 34b and extends substantially coaxially with respect to both the first passage 33 and the casing 34b. A driving belt is wound around the tip of the driving pulley 34d, and as described above, the crankshaft 15 is configured to be drivingly connected to the supercharger 34 in accordance with the switching state of the electromagnetic clutch 34a. .

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

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

  The core 36a is formed in a rectangular shape, and is supported in such a posture that one side surface (rear surface) of the core 36a faces the mounting surface 10a. The front surface of the core 36a constitutes a gas inflow surface, while the rear surface of the core 36a constitutes a gas outflow surface, each being the widest surface of the core 36a. Although not shown, the core 36a has a plurality of water tubes in which a thin plate material is formed into a flat cylindrical shape, and a corrugated fin corrugated fin is connected to the outer wall surface of each water tube by brazing or the like. . By comprising in this way, the cooling water supplied from the water supply pipe is introduce | transduced into each water tube, and cools high temperature gas. The cooling water warmed by cooling the gas is discharged from each water tube through the drain pipe. Further, by providing the corrugated fins, the surface area of each water tube is increased and the heat dissipation effect is improved.

  As shown in FIG. 4, the core connecting portion 36b is a rectangular thin plate-like member, and is attached to the right side surface of the core 36a. The water supply pipe, the drain pipe, and the water tube are connected to each other through the core connection portion 36b. The core connecting part 36b constitutes the right side wall part of the intercooler 36, and partitions the accommodation space for the core 36a together with the cooler housing 36c.

  The cooler housing 36 c is disposed below the casing 34 b that constitutes the supercharger 34, defines an accommodation space for the core 36 a, and includes a second passage 35 and a third passage 37 in the intake passage 30. A flow path interposed therebetween is configured.

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

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

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

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

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

  More specifically, as shown in FIG. 8, the upstream portion of the introduction portion 37 b extends obliquely upward to the right from the connection portion with the assembly portion 37 a (see section S <b> 2), while the downstream portion thereof is It is formed to extend directly upward toward the connection portion with the surge tank 38 (see section S1). As a result of this formation, the downstream end portion of the introduction portion 37b extends in a direction substantially orthogonal to the gas flow direction in the independent passage 39 when viewed from one side in the cylinder row direction (FIG. 7).

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

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

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

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

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

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

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

  As described above, the independent passage 39 is composed of the independent passage 391 corresponding to the first port 17 and the independent passage 392 corresponding to the second port 18 for each set. Therefore, when the parts constituting the third passage 37, the surge tank 38, the independent passage 39 and the like are assembled to the engine body 10, the first port 17 and the corresponding independent passage 391 constitute one passage. On the other hand, the second port 18 and the corresponding independent passage 392 constitute one independent passage. In this way, a total of eight independent passages are configured.

  In the independent passage 392 connected to the second port 18, as shown in FIG. 7, the SCV 81 constituting the flow control device 80 is disposed. Of the eight independent passages in total, the passage including the second port 18 serving as the SCV port and connected to the combustion chamber 16 via the second port 18 is an example of the “downstream passage”. doing. In this configuration example, a sign “72” is attached to the downstream passage, and the downstream passage 72 corresponding to the first cylinder 11A is referred to as a first downstream passage 72A, and the downstream passage 72 corresponding to the second cylinder 11B. Is called the second downstream passage 72B, the downstream passage 72 corresponding to the third cylinder 11C is called the third downstream passage 72C, and the downstream passage 72 corresponding to the fourth cylinder 11D is the second downstream passage. May be referred to as 72D. The SCV 81 is an example of a “flow control valve”.

  As shown in FIGS. 6 to 7, the SCV 81 is configured to open at least to a predetermined opening (in this example, an opening that is substantially perpendicular to the cylinder axis direction, preferably an opening that is perpendicular). It has a plate-like valve body 81a, and is configured to control the flow of gas flowing through the downstream side passage 72 by adjusting the opening degree of the valve body 81a. Since the flow rate of the gas passing through the second port 18 is reduced by reducing the opening degree of the valve body 81a, the four first ports 17 connected to the same cylinder 11 as the second port 18 are connected. The flow rate of the gas passing through the 1 port 17 can be relatively increased. Note that the SCV 81 may be disposed in the second port 18 connected to the independent passage 392 instead of the independent passage 392.

  The SCV 81 is configured such that the valve body 81a is opened by a valve shaft 82 extending in the engine output shaft direction. The valve body 81a is attached to the outer surface of the surge tank 38 on one side (right side) in the cylinder row direction. The actuator 83 is operated. The SCV 81, the valve shaft 82, and the actuator 83 constitute the flow control device 80 in this configuration example.

  As described above, the downstream portion of the bypass passage 40 is bifurcated, and the downstream ends of the branched passages (hereinafter referred to as “branch passages” 44 b and 44 c) are both the upper surface of the surge tank 38. It is connected to the.

  In order to realize such a connection structure, the first and second introduction portions arranged on the upper surface of the surge tank 38 with a space in the cylinder row direction and configured to communicate the inside and outside of the surge tank 38. 38c and 38d are provided.

  Of the first and second introduction portions 38c and 38d, the first introduction portion 38c located on one side (right side) in the cylinder row direction is also referred to as one branch passage (hereinafter referred to as “first branch passage”). ) The downstream end of 44 b is connected to the second introduction portion 38 d located on the other side (left side), and the downstream end of the other branch passage (hereinafter also referred to as “second branch passage”) 44 c. Are connected (see also FIG. 10).

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

  As shown in FIG. 8, the first introduction portion 38c is a portion in the surge tank 38 near the independent passage 392 corresponding to the second port 18B of the second cylinder 11B (near the upstream end portion of the second downstream passage 72B). It is arrange | positioned so that it may oppose. On the other hand, the second introduction portion 38d is disposed so as to face a portion in the vicinity of the independent passage 392 corresponding to the second port 18D of the fourth cylinder 11D (a portion in the vicinity of the upstream end portion of the fourth downstream passage 72D). Has been. The configuration of the first and second introduction portions 38 c and 38 d defines the connection location between the first and second branch passages 44 b and 44 c and the surge tank 38.

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

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

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

  As shown by an arrow A4 in FIG. 7, the gas flowing into the third passage 37 from the intercooler 36 passes through the collecting portion 37a and then flows obliquely upward to the right along the upstream portion of the introducing portion 37b ( 8 (see also section S1 in FIG. 8), and then flows directly upward along the downstream portion of the introduction portion 37b (see also section S2 in FIG. 8). As indicated by an arrow A5 in FIG. 7, the gas that has passed through the introduction portion 37b flows into a substantially central space in the surge tank 38 in the cylinder row direction, and is temporarily stored in the surge tank 38 before being independently stored. The air is supplied to the intake ports 17 and 18 of each cylinder 11 through the passage 39.

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

  10 is a view showing the passage structure on the bypass passage 40 side as viewed from above, FIG. 11 is a longitudinal sectional view showing a connection structure between the surge tank 38 and the bypass passage 40, and FIG. 12 is a view showing the bypass passage. It is a cross-sectional view which shows the channel | path structure from 40 to the combustion chamber 16 via the surge tank 38 in combination with SCV81 in a closed state.

  The bypass passage 40 extends upward from a branch portion provided on the upper surface of the first passage body 33b, and then extends substantially straight toward the right (see also FIGS. 4 and 5). When the portion of the bypass passage 40 extending rightward reaches the vicinity of the center of the surge tank 38 (specifically, the center in the cylinder row direction), the direction of the bypass passage 40 is changed so as to be obliquely downward and rearward. Branch to the crotch. Each of the branched branches is connected to the upper surface of the surge tank 38.

  Specifically, the bypass passage 40 includes, in order from the upstream side in the flow direction, a valve body 41a in which a bypass valve 41 is built, a curved pipe portion 42 that changes the flow direction of the gas that has passed through the valve body 41a, The straight pipe portion 43 that guides the gas that has passed through the curved pipe portion 42 to the right, and the gas that has passed through the straight pipe portion 43 are led obliquely downward and rearward, and then branched into two branches into the surge tank 38. It is comprised from the branch pipe part 44 connected.

  The valve body 41a is formed in a short cylinder shape, and as shown in FIG. 5, the openings at both ends are directed upward and downward on the first passage 33 and on the left side of the supercharger 34. Arranged in posture. Further, like the first passage 33, the valve body 41a is located in front of the portion near the left end of the mounting surface 10a. A branch portion of the first passage 33 is connected to the upstream end (lower end) of the valve body 41a, while an upstream end of the curved pipe portion 42 is connected to the downstream end (upper end) of the valve body 41a. .

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

  The straight pipe portion 43 is formed in a long cylindrical shape (specifically, a cylindrical shape extending in a direction from one side (left side) to the other side (right side) in the cylinder row direction). As can be seen, at the positions above the first passage 33 or the supercharger 34, the openings at both ends are arranged in a posture directed to the left and right. As described above, the downstream end (right end) of the curved pipe portion 42 is connected to the upstream end (left end) of the straight pipe portion 43, while the branch pipe is connected to the downstream end (right end) of the straight pipe portion 43. The upstream end of the portion 44 is connected.

  The branch pipe portion 44 includes a bent passage 44a bent in an elbow shape, and two branch passages 44b and 44c branched in a tournament form from the downstream end of the bent passage 44a. At a position above the surge tank 38, the bent passage 44a is disposed in such a posture that the upstream end of the bent passage 44a is directed leftward, and the two branched passages 44b, 44c are both directed obliquely downward and rearward.

  Specifically, the bent passage 44a is bent at a substantially right angle so as to go obliquely downward and rearward from the front as it goes from the left to the right. As shown in FIG. 10, the rear end portion of the bent passage 44a branches into two branch passages 44b and 44c in a substantially T shape when viewed in the cylinder axial direction.

  The flow path lengths of the two branch passages 44b and 44c are substantially the same, and the first branch passage 44b, which is one of the branched branch passages, extends rightward from the branch location along the cylinder row direction. After that, it is bent so as to go diagonally downward and rearward. On the other hand, the second branch passage 44c, which is the other branch passage branched, extends to the left along the cylinder row direction from the branch portion, and is then bent obliquely downward and rearward. As described above, the downstream end portions of the two branch passages 44b and 44c are connected to the first introduction portion 38c and the second introduction portion 38d formed on the upper surface of the surge tank 38, respectively.

  When the components constituting the bypass passage 40 are attached to the surge tank 38, each of the two branch passages 44b and 44c and each of the first introduction portion 38c and the second introduction portion 38d pass through one passage. It is configured. Each of these two passages has a downstream end portion (that is, each of the first introduction portion 38c and the second introduction portion 38d) connected to the upstream side of the downstream passage 72, and the surge tank 38 as a relay portion. The gas is supplied to the combustion chamber 16 via the two, and both illustrate “upstream passages”. In this configuration example, the upstream passage is denoted by reference numeral “71”, and the upstream passage 71 corresponding to the first branch passage 44b and the first introduction portion 38c is referred to as a first upstream passage 71A, and the second branch passage. The upstream passage 71 corresponding to 44c and the second introduction portion 38d may be referred to as a second upstream passage 71B.

  The downstream passage 72 is connected to the upstream passage 71 via a surge tank 38 serving as a relay unit.

  During natural intake, the gas flowing into the bypass passage 40 passes through the respective parts 41 to 44 constituting the bypass passage 40 and reaches each cylinder 11.

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

  As shown by an arrow A6 in FIG. 10, the gas that has passed through the valve body 41a and has flowed into the curved pipe portion 42 flows rightward, and then flows to the right while slightly moving backward.

  Subsequently, the gas that has passed through the curved pipe portion 42 flows to the right along the straight pipe portion 43 and then flows into the branch pipe portion 44 as indicated by an arrow A7 in FIG. Then, as shown by arrows A8 to A10 in the figure, the gas flowing into the branch pipe portion 44 passes through the bending passage 44a and is then distributed to the first branch passage 44b and the second branch passage 44c. Each flowed into the surge tank 38 (see also arrows A9 to A10 in FIGS. 11 to 12). The gas flowing into the surge tank 38 is supplied to the intake ports 17 and 18 of each cylinder 11 through the independent passage 39.

  On the other hand, at the time of supercharging, the gas flowing backward from the surge tank 38 to the bypass passage 40 passes through the respective portions 41 to 44 of the bypass passage 40 in the direction opposite to that during natural intake and flows out to the first passage 33. .

−Intake port configuration−
Hereinafter, the structure of the intake ports 17 and 18 will be described in detail. As described above, both the first port 17 and the second port 18 as the intake ports 17 and 18 have a so-called tumble port shape. Since the tumble port shape is closely related to the configuration around the combustion chamber 16, the configuration around the combustion chamber 16 will be described in detail first. FIG. 13 is a diagram for explaining an intake port structure having a tumble port shape and a structure of a combustion chamber.

  The ceiling surface 90 of the combustion chamber 16 has a pent roof shape as described above, and is constituted by the lower surface of the cylinder head 13. Specifically, as shown in FIG. 13, when the combustion chamber 16 is viewed in the direction of the engine output shaft, the ceiling surface 90 has a cylinder axis (reference numeral “C” only in FIGS. 12 to 14 for the sake of simplicity). The intake-side inclined surface is inclined upward toward the cylinder axis C, and the exhaust-side inclined surface is inclined upward from the exhaust side toward the cylinder axis C.

  Two intake ports 93 are opened on the intake side inclined surface (only one is shown in FIG. 13). Although not shown in detail, the two intake ports 93 are arranged side by side in the engine output shaft direction. A ring-shaped valve seat is disposed on the peripheral edge of each intake port 93.

  The first port 17 and the second port 18 are connected to each of the two intake ports 93. For convenience, only the configuration related to the second port 18 will be described below, but the configuration of the first port 17 is the same.

  The second intake port 18 is provided with the aforementioned intake valve 21. The intake valve 21 is configured to be driven by a valve mechanism (not shown) (for example, a DOHC type mechanism), and opens and closes the intake port 93 by reciprocating up and down.

  Specifically, the intake valve 21 is configured as a so-called poppet valve. Specifically, the intake valve 21 is connected to a valve stem (shaft portion) 211 that reciprocates up and down, and a lower end portion of the valve stem 211 and contacts the intake port 93 from the inside (inward side) of the combustion chamber 16. It has a valve head (umbrella part) 212 configured to close the intake port 93 from the combustion chamber 16 by being in contact therewith.

  The valve stem 211 is inserted through a cylindrical valve guide (not shown) and moves up and down in the axial direction. The lower end portion of the valve stem 211 is connected to the umbrella back 212 a of the valve head 212. On the other hand, the upper end portion of the valve stem 211 is connected to the aforementioned valve mechanism.

  The valve head 212 closes the intake port 93 from the inside of the combustion chamber 16 by bringing the umbrella back 212 a into close contact with the valve seat 94 provided in the intake port 93. When the intake valve 21 moves downward from this state, the umbrella back 212a and the valve seat 94 are separated from each other, and the intake port 93 is opened. At this time, the flow rate of the intake air flowing into the combustion chamber 16 from the second port 18 is adjusted according to the distance between the umbrella back 212a and the valve seat 94 (so-called valve lift amount).

  Next, the tumble port shape of the second port 18 will be described. This description is the same for the first port 17.

  The downstream portion of the second port 18 is inclined with respect to the cylinder axis C in a cross-sectional view perpendicular to the engine output shaft. Specifically, as shown in FIG. 13, the downstream end of the second port 18 is located with respect to the combustion chamber 16 from the intake side toward the cylinder axis C when the combustion chamber 16 is viewed in the engine output shaft direction. It extends toward the lower side (combustion chamber 16 side in the cylinder axis C direction) from a position away from the upper side, and is connected to the air inlet 93 of the ceiling surface 90.

  Here, the downstream end of the second port 18, particularly the lower half of the downstream end, is opened when the intake valve 21 corresponding to the second port 18 opens the intake port 93 (at least, When the valve lift amount reaches the maximum amount), in the cross-sectional view perpendicular to the engine output shaft, the umbrella back 212a of the valve head 212 that is located on the cylinder axis C side with respect to the valve stem 211, It extends so as to be directed to the ceiling surface 90 facing the umbrella back 212a (see arrows a1 to a2 in FIG. 13).

  With this configuration, when the intake valve 21 opens the intake port 93, the intake air that flows into the combustion chamber 16 from the second port 18 flows between the umbrella back 212a and the ceiling surface 90 that faces the umbrella back 212a. Led to. The intake air thus guided flows from the inner peripheral surface of the cylinder 11 on the side opposite to the intake valve 21 across the cylinder axis C (that is, the exhaust side) toward the lower side in the vertical direction (cylinder axis C direction). After that, it flows upward in the vertical direction toward the intake valve 21. Thus, the intake air flowing into the combustion chamber 16 generates a swirling flow around the central axis parallel to the engine output shaft. Therefore, the strength of the tumble flow is increased in the combustion chamber 16.

(Configuration related to gas introduction)
FIG. 14 is a cross-sectional view showing a passage structure from the bypass passage 40 to the combustion chamber 16 through the surge tank 38 together with the SCV 81 in an open state. 15 is a plan view showing the flow path structure around the surge tank 38 as viewed from above, and FIG. 16 is a rear view showing the flow path structure as viewed from the rear side. 15 to 16 both correspond to the shape of the core when the members around the surge tank 38 are cast.

  The engine 1 includes an ECU for operating the engine 1. The ECU determines the operating state of the engine 1 based on detection signals output from various sensors, and calculates control amounts of various actuators. Then, the ECU sends control signals corresponding to the calculated control amounts to the electromagnetic waves of the injector 6, spark plug 25, intake electric VVT 23, exhaust electric VVT 24, fuel supply system 61, throttle valve 32, EGR valve 54, and supercharger 34. The engine 1 is operated by outputting to the clutch 34a, the bypass valve 41, the flow control device 80, and the like.

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

  For example, the ECU operates the engine 1 by natural intake air in an operation region (hereinafter referred to as a “fuel consumption region”) on a lower load side than a predetermined load. Specifically, the ECU disconnects the electromagnetic clutch 34a and fully opens the bypass valve 41.

  On the other hand, the ECU supercharges the gas introduced into each cylinder 11 by driving the supercharger 34 in an operation region (hereinafter referred to as “supercharging region”) higher than the predetermined load. . Specifically, the ECU connects the electromagnetic clutch 34a and adjusts the opening degree of the bypass valve 41 as appropriate.

  In addition, the ECU generates swirl in the low load side in the fuel consumption region (low load side when the fuel consumption region is divided into a low load side and a high load side by a predetermined value different from the predetermined load). In order to promote this, the SCV 81 is closed by closing the valve body 81a. As a result, the flow rate of the gas passing through the first port 17 is relatively increased, and gas mixing can be promoted.

  On the other hand, the ECU opens the SCV 81 by opening the valve body 81a to the aforementioned predetermined opening degree in order to ensure the amount of gas introduced from the high load side region to the supercharging region in the fuel efficiency region. Since the SCV 81 is opened, the total flow rate of the gas passing through the two intake ports 17 and 18 is relatively increased, and a large amount of air-fuel mixture can be formed in the combustion chamber 16.

-Configuration related to flow control valve-
In recent years, in the engine 1 provided with the flow control valve such as the SCV 81 or the tumble control valve (TCV) described above, reduction of pump loss is required from the viewpoint of improving thermal efficiency, for example. In order to reduce the pump loss, it is required to smoothly guide the gas reaching the combustion chamber 16 through various passages such as the bypass passage 40.

  As a result of intensive studies, the inventors of the present application have found that there is room for improvement in guiding the gas to the combustion chamber 16 regarding the configuration and layout of the flow control valve including the SCV81.

  Hereinafter, the structure relevant to SCV81 as a flow control valve is demonstrated in detail.

  Here, for convenience, the configuration related to the first upstream passage 71A and the second downstream passage 72B will be described. However, for example, the configuration related to the second upstream passage 71B and the fourth downstream passage 72D is also described. It is the same.

  As shown in FIGS. 12 to 14, the downstream end portion of the first upstream passage 71 </ b> A (in this configuration example, it corresponds to the first introduction portion 38 c, and will be denoted by “38 c” below), The upstream end portion of the downstream passage 72B (which corresponds to the independent passage 392 in this configuration example, is denoted by the reference numeral “392” below) is configured to be directed in different directions. Specifically, the downstream end 38c of the first upstream passage 71A is directed obliquely downward and rearward, while the upstream end 392 of the second downstream passage 72B is directed substantially rearward. This is equivalent to the downstream end 38c of the first upstream passage 71A being connected to the surge tank 38 at a predetermined angle with respect to the upstream end 392 of the second downstream passage 72B.

  Further, as shown in FIG. 12, when the valve body 81a closes the second downstream passage 72B, the downstream end portion 38c of the first upstream passage 71A is configured not to face the valve body 81a. ing.

  Specifically, when the valve body 81a of the SCV 81 is in the closed state, the upper end side is positioned rearward, and the lower end side is inclined so as to protrude forward, and corresponds to the second downstream side passage 72B. The independent passage 392 is closed.

  And the extension lines L1 and L2 extending along the gas flow direction from the inner wall surface of the downstream end portion 38c of the first upstream passage 71A do not intersect with the valve body 81a in the closed state. Yes. These extension lines L1 and L2 are extension lines in a cross-sectional view perpendicular to the engine output shaft in the illustrated example, but are not limited thereto. At least, it may be an extension line in a cross-sectional view perpendicular to the valve shaft 82.

  In this case, for example, in the fuel efficiency region, the gas that has flowed into the surge tank 38 via the downstream end 38c of the first upstream passage 71A is blown to the inner bottom surface 38a of the surge tank 38, and then passes through the independent passages 391 and 392. Then, the air is sucked into the cylinder 11 in the intake stroke (that is, the cylinder 11 having a negative pressure relative to the surge tank 38).

  As can be seen from a comparison between FIG. 12 and FIG. 14, the valve body 81 a of the SCV 81 rotates counterclockwise in a cross-sectional view perpendicular to the engine output shaft when opening from the closed state to a predetermined opening.

  Thus, when the valve body 81a is opened to a predetermined opening, the downstream end portion 38c of the first upstream passage 71A faces at least a part of the valve body 81a (particularly, the front surface or the back surface of the valve body 81a). It is configured as follows.

  Specifically, when the valve body 81a of the SCV 81 is opened to a predetermined opening, the portion of the valve body 81a that is on the upper end side in the closed state protrudes rearward from the independent passage 392 and enters the second port 18B. On the other hand, the portion of the valve body 81a that is on the lower end side in the closed state protrudes forward from the independent passage 392 (that is, the second downstream passage 72B itself) and enters the surge tank 38.

  And at least one of the extension lines L1 and L2 extending along the gas flow direction from the inner wall surface of the downstream end portion 38c of the first upstream passage 71A intersects with the portion that has entered the surge tank 38 along with the opening operation. It will be. This is because the downstream end 38c of the first upstream passage 71A and at least a part of the valve body 81a (particularly, the front surface or the back surface of the valve body 81a), in particular, a part protruding from the independent passage 392 are opposed to each other. It is equivalent to doing.

  In this case, for example, in the fuel efficiency region, at least a part of the gas flowing into the surge tank 38 via the downstream end 38c of the first upstream passage 71A is a portion protruding from the second downstream passage 72B in the valve body 81a. If the cylinder 11 corresponding to the valve body 81a to which the gas is blown is in the intake stroke after being blown, the second downstream passage 72B is introduced.

  Further, the inner wall surface of the second downstream passage 72B is arranged such that one side close to the combustion chamber 16 in the cylinder axis C direction (lower side in this configuration example) and the other side separated from the combustion chamber 16 (in this configuration example). When the valve body 81a is opened to a predetermined opening degree, the valve body 81a moves in the downstream passage 72 from the upstream side to the downstream side (front side to rear side) along the gas flow direction. It extends so as to be directed toward the other inner wall surface (in this configuration example, the upper inner wall surface).

  Therefore, the gas blown to the valve body 81a and introduced into the second downstream passage 72B flows along the upper inner wall surface directed to the valve body 81a, and is then introduced into the combustion chamber 16.

  As described above, for example, when the operating state of the engine 1 is in the fuel consumption range, the valve body 81a of the SCV 81 as the flow control valve opens to a predetermined opening. At that time, as shown in FIG. 14, at least a part of the valve body 81a (particularly, the front surface or the back surface of the valve body 81a) faces the downstream end portion 38c of the first upstream passage 71A.

  That is, for example, when the downstream end 38c of the first upstream passage 71A and the upstream end 392 of the second downstream passage 72B are directed in different directions, the gas flowing out of the first upstream passage 71A is The second downstream passage 72B does not flow smoothly but collides with the wall 38a near the upstream end 392. This is inconvenient for guiding the gas smoothly.

  On the other hand, as shown in FIG. 14, the gas flowing out from the first upstream passage 71A collides with the valve body 81a configured to face the downstream end portion 38c. The valve body 81a is provided in the second downstream side passage 72B, the second downstream side passage 72B is opened along with the opening operation of the valve body 81a, and the second downstream side passage 72B is In consideration of a relatively negative pressure in the intake stroke, the gas colliding with the valve body 81a flows smoothly through the open second downstream passage 72B. As a result, the gas can be smoothly guided to the combustion chamber 16.

  Further, as shown in FIG. 14, the downstream end 38c of the first upstream passage 71A and the upstream end 392 of the second downstream passage 72B do not face each other. The gas flowing out from the first upstream passage 71A is guided to the second downstream passage 72B through the valve body 81a facing the downstream end portion 38c. This is advantageous in smoothly leading the gas to the combustion chamber 16.

  Further, as shown in FIG. 14, the gas flowing out from the first upstream passage 71A does not reach the inside of the second downstream passage 72B, but passes through the valve body 81a protruding from the second downstream passage 72B. Will flow into. This means that the gas can be smoothly guided to the combustion chamber 16 while maintaining the degree of freedom of the relative positional relationship between the first upstream passage 71A and the second downstream passage 72B. This is advantageous in determining the layout.

  In addition, if the surge tank 38 is interposed between the first upstream side passage 71A and the second downstream side passage 72B, there is a possibility that it may be disadvantageous to guide the gas to the combustion chamber 16 depending on the shape and layout of the surge tank 38. There is.

  However, as shown in FIG. 14, a part of the valve body 81a protrudes from the second downstream passage 72B and enters the surge tank 38. Since this portion faces the downstream end portion 38c of the first upstream passage 71A, it is advantageous for smoothly guiding the gas to the combustion chamber 16 as described above.

  Further, according to the embodiment, the second port 18 has a tumble port shape. Therefore, the strength of the tumble flow can be increased in the combustion chamber 16.

  Here, in order to further increase the strength of the tumble flow, it is required to increase the flow of the gas in the vertical direction. As a measure for this, it is conceivable that gas flows along the upper inner wall surface spaced from the combustion chamber 16 in the cylinder axial direction in the second downstream passage 72B including the second port 18. With this configuration, the flow in the vertical direction is strengthened by the distance away from the combustion chamber 16 as compared with the case where the gas flows along the lower inner wall surface close to the combustion chamber 16 in the cylinder axial direction. Is possible.

  Therefore, as shown in FIG. 14, when the valve body 81a is opened to a predetermined opening degree, the inner side of the upper side in the second downstream passage 72B increases from the upstream side to the downstream side along the gas flow direction. It extends to face the wall. If comprised in this way, the gas which flows along the valve body 81a will flow toward an upper inner wall face as shown by arrow A9 'of FIG. 14, and will flow along the upper inner wall face. Thereby, the strength of the tumble flow can be further increased.

-Configuration related to gas blowback-
As described above, the engine 1 performs combustion in the order of the first cylinder 11A, the third cylinder 11C, the fourth cylinder 11D, and the second cylinder 11B during operation.

  Hereinafter, the two cylinders 11 that are in the order of combustion and are adjacent to each other in the cylinder row direction may be referred to as a first cylinder and a second cylinder in the order in which combustion occurs. In other words, in the case of the engine 1, the second cylinder 11B is the first set of the first cylinder, the first cylinder 11A is the first set of the subsequent cylinder, and the third cylinder 11C is the second set of the first cylinder. In addition, a pair in which the fourth cylinder 11D is a second set of subsequent cylinders is configured. Hereinafter, unless otherwise specified, the first set of the first and second cylinders will be described. In this case, the same reference numeral “11B” as that of the second cylinder 11B is assigned to the first cylinder, while the same reference numeral “11A” as that of the first cylinder 11A is assigned to the subsequent cylinder.

  By the way, in the engine 1 as in the above-described embodiment, for example, from the viewpoint of securing in-cylinder temperature and reducing pump loss, a negative overlap period (NVO) is provided through the internal EGR system in the above-described fuel consumption region. Can be considered.

  Specifically, the exhaust electric VVT 24 maintains the closing timing of the exhaust valve 22 (hereinafter referred to as “EVC”) at a predetermined crank angle before the exhaust top dead center in accordance with a control signal received from the ECU in the fuel consumption range. To do. Since the EVC is adjusted by the exhaust electric VVT 24, when the EVC is kept substantially constant, the EVO is also kept substantially constant. In this way, the exhaust electric VVT 24 sets EVC during the exhaust stroke.

  In contrast, intake electric VVT 23 sets the opening timing of intake valve 21 (hereinafter referred to as “IVO”) to a predetermined crank angle after exhaust top dead center in accordance with a control signal received from the ECU in the fuel consumption range. . Therefore, in this fuel consumption region, a negative overlap period in which both the intake valve 21 and the exhaust valve 22 are closed across the exhaust top dead center is provided.

  In this engine 1, the intake electric VVT 23 sets IVC between the first half and the middle half of the compression stroke. That is, in the engine 1, so-called “slow closing” of the intake valve 21 can be performed. By performing the slow closing, the gas filling amount can be reduced.

  By providing the negative overlap period, the burned gas is confined in the combustion chamber 16 (in other words, the internal EGR gas is introduced). As a result, the temperature in the combustion chamber 16, particularly the temperature before ignition, increases. Thereby, for example, when compression ignition combustion is performed instead of general spark ignition combustion in order to improve fuel efficiency, the combustion can be stably performed. Moreover, since IVC is delayed, the filling amount of gas is reduced. Although the filling amount is reduced in the fuel consumption region, the mirror cycle is realized with the provision of the negative overlap period, so that throttling can be omitted or suppressed. As a result, pump loss is reduced.

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

  In particular, when the surge tank 38 is disposed in the vicinity of the inlets of the intake ports 17 and 18 as in the above embodiment, the gas blown back to the intake side passes through the intake ports 17 and 18 and the independent passages 391 and 392. Therefore, there is a possibility that the surge tank 38 flows backward.

  On the other hand, in the case of a four-cylinder engine, when the preceding cylinder 11B defined as described above is in the compression stroke, the subsequent cylinder 11A is in the middle of the intake stroke. Therefore, when gas is blown back from the preceding cylinder 11B, the interior of the succeeding cylinder 11A becomes negative pressure. Therefore, considering that the leading cylinder 11B and the succeeding cylinder 11A are adjacent to each other in the cylinder row direction, the runner length is The inventors of the present application have noticed that the gas blown back from the starting cylinder 11B may be sucked into the succeeding cylinder 11A during the intake stroke via the surge tank 38 because of the short configuration.

  As a result of further studies, the inventors of the present application have accelerated the suction of the gas blown back from the preceding cylinder 11B into the succeeding cylinder 11A, depending on the connection location between the bypass passage 40 and the surge tank 38. As a result, it has been found that there is a risk of reaching so-called pre-ignition (hereinafter also referred to as “pre-ignition”).

  For example, as is well known, it is conceivable to connect the bypass passage 40 to the central portion of the surge tank 38 in the cylinder row direction (between the second cylinder 11B and the third cylinder 11C in this configuration example).

  In this case, the connection portion of the bypass passage 40 and the surge tank 38, the upstream end portion of the independent passage 39 that communicates with the starting cylinder 11B, and the upstream end portion of the independent passage 39 that communicates with the succeeding cylinder 11A are arranged in the cylinder row direction. They will be arranged in order. As a result, the gas flowing into the surge tank 38 from the bypass passage 40 is located inside the surge tank 38 in the space near the upstream end of the independent passage 39 corresponding to the preceding cylinder 11B and the independent passage 39 corresponding to the succeeding cylinder 11A. A flow is formed so as to pass through the space near the upstream end in this order. As a result, the gas flowing into the surge tank 38 from the bypass passage 40 becomes “trailing wind”, and the gas blown back from the preceding cylinder is pushed away to the succeeding cylinder. Specifically, when such a tailwind is generated, the gas blown back from the starting cylinder 11B is pushed away toward the succeeding cylinder 11A.

  As a result of the gas blown back from the starting cylinder 11B being pushed away by the gas flowing in from the bypass passage 40, the inventors of the present application may inhale the gas excessively in the succeeding cylinder 11A, and as a result, there is a risk of reaching the pre-ignition. I noticed that there is.

  In order to suppress the plague, the bypass passage 40 is connected to the end of the surge tank 38 in the cylinder row direction (in this configuration example, from the first cylinder 11A so that the gas flowing in from the bypass passage 40 becomes a “heading wind”. Can also be connected to the right side or the left side of the fourth cylinder 11D.

  In this case, the connecting portion of the bypass passage 40 and the surge tank 38, the upstream end portion of the independent passage 39 communicating with the succeeding cylinder 11A, and the upstream end portion of the independent passage 39 communicating with the starting cylinder 11B are arranged in this order in the cylinder row direction. Will be lined up. However, with such a configuration, although the suction of the blown-back gas is suppressed, the flow from the bypass passage 40 to the preceding cylinder 11B with respect to the passage length from the bypass passage 40 to the succeeding cylinder 11A. Since the road length becomes long, the responsiveness may be deteriorated in the starting cylinder 11B. Also, if the flow path length differs between cylinders, there is a possibility that the difference between cylinders may increase in the state quantity such as the charging efficiency.

  As another measure for suppressing the plague, for example, it is conceivable to increase the capacity of the surge tank 38. In this case, however, the volume of the entire intake passage 30 is increased by the increase in the capacity of the surge tank 38. For this reason, it is not preferable in that it may cause a decrease in the supercharging response particularly when configured in combination with the supercharger 34. In addition, such a configuration is inconvenient because the layout of peripheral parts of the intake passage 30 may be hindered.

  However, in this configuration example, as described above, the first introduction portion 38c to which the surge tank 38 and the bypass passage 40 are connected corresponds to the second port 18B of the second cylinder 11B as shown in FIG. It is disposed at a location near the independent passage 392. As a result, the connection location between the bypass passage 40 and the surge tank 38 is independent from the upstream end of the independent passage 392 corresponding to the starting cylinder 11B among the plurality of independent passages 39 in the cylinder row direction. It is set so as to face the section extending to the upstream end of the passage 391.

  Moreover, the gas passing through the first branch passage 44b connected to the first introduction portion 38c is directed to the right in the cylinder row direction in accordance with the extending direction of the first branch passage 44b. Considering that the first cylinder 11A as the next cylinder is adjacent to the right side with respect to the second cylinder 11B as the first cylinder, the first branch passage 44b allows the gas flowing through the first branch passage 44b to flow. It is equivalent to being formed so as to be directed toward the succeeding cylinder 11A out of the starting cylinder 11B and the succeeding cylinder 11A.

  More specifically, as shown in FIG. 16, the downstream end of the first branch passage 44b is an independent passage 392 connected to the second port 18B of the second cylinder 11B when the intake passage 30 is viewed from the rear. Are arranged so as to overlap each other (see region O1 in FIG. 16).

  With this configuration, when the succeeding cylinder 11A is in the intake stroke (that is, when the vicinity of the upstream end corresponding to the succeeding cylinder 11A is negative in the surge tank 38), the surge tank 38 is connected to the bypass passage 40. The gas that has flowed into the cylinder is coupled with the gas blown back from the preceding cylinder 11B (see the arrow A11 in FIG. 15) in combination with the fact that the gas is directed toward the succeeding cylinder 11A. A flow toward the 11A side (see arrow A9 in FIG. 15) is formed.

  Therefore, for the gas blown back from the starting cylinder 11B, the gas flowing in from the bypass passage 40 is less likely to become “trailing wind”. As a result, it is possible to suppress the suction of the gas blown back from the preceding cylinder 11B into the succeeding cylinder 11A, and thus suppress the occurrence of pre-ignition.

  Moreover, as compared with the configuration in which the bypass passage 40 is connected to the right end of the surge tank 38, the difference between the cylinders such as the charging efficiency is reduced, and the same level of responsiveness is secured in the starting cylinder 11B and the starting cylinder 11A. Is possible.

  The same applies to the second set of the first cylinder (third cylinder 11C) and the second cylinder (fourth cylinder 11D). In this case, the bypass passage 40 and the surge tank 38 are connected to the succeeding cylinder from the upstream end of the independent passage 39 corresponding to the starting cylinder (third cylinder) 11C among the plurality of independent passages 39 in the cylinder row direction. (4th cylinder) It is set to oppose in the section to the upstream end part of independent passage 39 corresponding to 11D. In addition, the second branch passage 44c connected to the second introduction portion 38d directs the gas flowing through the second branch passage 44c toward the succeeding cylinder 11D out of the preceding cylinder 11C and the succeeding cylinder 11D (that is, Equal to the left side).

  As shown in FIG. 16, the downstream end of the second branch passage 44c is upstream of the independent passage 392 connected to the second port 18D of the fourth cylinder 11D when the intake passage 30 is viewed from the front. It arrange | positions so that it may mutually overlap with an edge part (refer area | region O2 of FIG. 16).

  By configuring in this way, also in the third cylinder 11C and the fourth cylinder 11D, it is possible to suppress the occurrence of pre-age due to gas blowback while ensuring the responsiveness of each cylinder 11.

<< Other embodiments >>
In the said embodiment, although illustrated about the horizontal engine 1 mounted in the vehicle of FF system, it is not restricted to this structure. For example, it may be a vertical engine mounted on an FR vehicle.

  Moreover, in the said embodiment, although illustrated about the inline 4 cylinder engine, it is not restricted to this structure. For example, a 1-cylinder engine or an in-line 6-cylinder engine may be used. Further, the number of passages branched in the bypass passage 40 may be changed according to the number of cylinders.

  Moreover, in the said embodiment, although the flow control device 80 was comprised using the common valve shaft 82 and the actuator 83 with respect to all the four SCV81, it is not restricted to this structure. For example, for each SCV 81, a valve shaft extending in the vertical direction and an actuator for driving each valve shaft may be provided. Further, the opening direction of the valve body 81a is also changed according to the extending direction of the valve shaft 82, and the connection structure between the bypass passage 40 and the surge tank 38 may be modified so as to correspond to the change.

  Further, the supercharging passage constituted by the second passage 35 and the third passage 37 may be regarded as the upstream passage. In this case, the opening direction of the valve body 81a may be changed according to the shape and layout of the third passage 37 in particular.

  In the above embodiment, the supercharger 34 configured as a so-called supercharger is illustrated, but a turbocharger may be used. In the first place, the supercharger 34 is not essential.

1 Engine 10 Engine body 11 Cylinder
11A No. 1 cylinder (the first set of subsequent cylinders)
11B No. 2 cylinder (first cylinder of the first set)
11C 3rd cylinder (2nd set starting cylinder)
11D 4th cylinder (2nd set of succeeding cylinders)
16 Combustion chamber 17 1st port (intake port)
18 Second port (intake port, downstream passage)
21 Intake valve 211 Valve stem (shaft)
212 Valve head (umbrella)
212a Umbrella 23 Intake electric VVT (Variable valve mechanism)
30 Intake passage 38 Surge tank (relay part)
38c 1st introduction part (upstream passage)
38d 2nd introduction part (upstream passage)
39 Independent passage 391 Independent passage 392 Independent passage (upstream end of downstream passage)
40 Bypass passage 44b First branch passage (downstream end of upstream passage)
44c Second branch passage (downstream end of upstream passage)
71 Upstream passage 72 Downstream passage 80 Flow control device 81 Swirl control valve 81a Valve body 82 Valve shaft 90 Ceiling surface 93 Air inlet C Cylinder shaft

Claims (5)

An intake passage connected to a combustion chamber, the intake passage including an upstream side passage and an intake port, and connected to the upstream side passage via a relay portion; Intake of an engine having a downstream passage connected to the chamber via the intake port, and a flow control valve provided in the downstream passage and controlling the flow of gas through adjusting the opening of the valve body A passage structure,
An intake passage structure for an engine, wherein a downstream end portion of the upstream passage is configured to face at least a part of the valve body when the valve body is opened to a predetermined opening degree. The intake passage structure for an engine according to claim 1,
An intake passage structure for an engine, wherein a downstream end portion of the upstream passage is connected to the relay portion at a predetermined angle with respect to an upstream end portion of the downstream passage. The engine intake passage structure according to claim 1 or 2,
When the valve body opens to the predetermined opening,
At least a portion of the valve body protrudes from the downstream passage and enters the relay portion,
An intake passage structure for an engine, wherein a downstream end portion of the upstream passage is configured to face a portion of the valve body protruding from the downstream passage. The intake passage structure for an engine according to any one of claims 1 to 3,
The engine further includes an intake valve that is provided in the intake port and configured to open and close an intake port that is open to a ceiling surface of the combustion chamber.
The intake valve is connected to a shaft portion that reciprocates up and down, and a lower end portion of the shaft portion, and is configured to close the intake port by contacting the intake port from the inner side of the combustion chamber. An umbrella part, and
The downstream end portion of the intake port is a portion of the umbrella portion that is located closer to the cylinder shaft than the shaft portion in a cross-sectional view perpendicular to the engine output shaft when the intake valve opens the intake port. It extends to point between the back of the umbrella and the ceiling surface facing the back of the umbrella,
The flow control valve is configured such that the valve element is opened by a valve shaft extending in the engine output shaft direction.
When the inner wall surface in the downstream passage is divided into one side close to the combustion chamber in the cylinder axis direction and the other side separated from the combustion chamber, the valve element opens to the predetermined opening degree. An intake passage structure for an engine, wherein the intake passage structure extends toward an inner wall surface on the other side of the downstream passage as it goes from the upstream side to the downstream side along the gas flow direction. The intake passage structure for an engine according to any one of claims 1 to 4,
The engine is
An engine body having a plurality of cylinders arranged in a row and configured to perform combustion in a predetermined combustion order in each of the plurality of cylinders;
A plurality of intake ports provided in the engine body, each communicating with each of the plurality of cylinders;
A plurality of intake valves each for opening and closing each of the plurality of intake ports;
A variable valve mechanism that changes the opening and closing timing of the plurality of intake valves,
The variable valve mechanism is configured to set the closing timing of the plurality of intake valves during a compression stroke when the operating state of the engine body is in a predetermined operating region,
The downstream passage is
Each of the plurality of intake ports;
A plurality of independent passages each connected to each of the plurality of intake ports,
The relay portion is disposed to face the opposite side across the plurality of independent passages with respect to the opposite cylinder side ends of the plurality of intake ports, and the upstream ends of the plurality of independent passages correspond to each other. It is configured as a surge tank connected in a line according to the order of cylinders,
The upstream side passage is configured such that a downstream end thereof is connected to the surge tank and gas is introduced into the surge tank,
Of the plurality of cylinders, two cylinders whose combustion order is adjacent and adjacent in the cylinder row direction are referred to as a first cylinder and a second cylinder in the order in which combustion occurs. Is connected in the cylinder row direction in the section from the upstream end of the independent passage corresponding to the preceding cylinder to the upstream end of the independent passage corresponding to the succeeding cylinder in the plurality of independent passages. Is set as
The engine intake passage structure according to claim 1, wherein the upstream passage is formed so as to direct the gas flowing through the upstream passage toward the succeeding cylinder of the preceding cylinder and the succeeding cylinder.

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