Engine intake and exhaust systems

Abstract

To suppress discharging of unburned fuel.SOLUTION: An intake / exhaust system 1 of an engine 100 includes an intake flow passage 200 communicating with a combustion chamber 108 of an engine 100 and provided with a fuel injection valve, a connection flow passage 500 connecting a first part P1 and second part P2 of the intake flow passage 200, and a gas delivery part (compressor 602) provided in the connection flow passage 500.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an intake and exhaust system for an engine. [Background technology]

[0002] There is an engine having a combustion chamber, an intake valve, and an exhaust valve. In such an engine, as disclosed in Patent Document 1, for example, an intake port communicating with the combustion chamber is opened and closed by the intake valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 049878 Summary of the Invention [Problem to be solved by the invention]

[0004] In a system in which a fuel injection valve is provided in the intake passage, some of the fuel injected from the fuel injection valve may remain in the intake port when the intake valve is closed. When switching from the exhaust stroke to the intake stroke, both the intake valve and the exhaust valve may be open. When both the intake valve and the exhaust valve are open, unburned fuel remaining in the intake port may be discharged through the exhaust port, a phenomenon known as "blow-by." From the perspective of improving thermal efficiency or reducing greenhouse gas emissions, it is desirable to reduce the discharge of unburned fuel due to blow-by.

[0005] An object of the present disclosure is to provide an engine intake and exhaust system that can suppress the emission of unburned fuel. [Means for solving the problem]

[0006] In order to solve the above problems, the intake and exhaust system of the engine of the present disclosure includes: an engine having a plurality of cylinders, each cylinder having a combustion chamber, an intake port and an exhaust port opening into the combustion chamber, an intake valve for opening and closing the intake port, and an exhaust valve for opening and closing the exhaust port; and a plurality of first branch flow paths respectively communicating with the plurality of combustion chambers;an intake passage in which a fuel injection valve is provided; a connecting passage connecting a first portion and a second portion of the intake passage; , and delivers gas from the first portion to the second portion. a gas delivery section; The first portion is each of a plurality of first branch flow paths, the connecting flow path has a plurality of second branch flow paths connected to the plurality of first branch flow paths, respectively, and each of the plurality of second branch flow paths is provided with an on-off valve, and the control device opens the on-off valve of the second branch flow path connected to the intake port of the cylinder whose intake valve is closed, and closes the on-off valve of the second branch flow path connected to the intake port of the cylinder whose intake valve is open. .

[0007] The gas delivery section may include a first supercharger having a first turbine and a first compressor provided in the connecting flow path, and the gas delivery section may be the first compressor.

[0008] The engine may include an exhaust flow path communicating with the combustion chamber, and the first turbine may be disposed in the exhaust flow path.

[0009] The engine may include a second turbocharger having a second turbine provided in the exhaust flow path and a second compressor provided in the intake flow path, the exhaust flow path connecting the upstream side and downstream side of the second turbine in the exhaust flow path and including a first wastegate flow path in which a first wastegate valve is provided, and the first turbine may be provided in the first wastegate flow path.

[0010] The first turbine may be provided in the intake flow path.

[0011] The upstream side and downstream side of the flow passage in which the first turbine is provided may be connected by a second wastegate flow passage in which a second wastegate valve is provided. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to suppress the emission of unburned fuel. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an intake and exhaust system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of each cylinder of the engine according to the embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic diagram showing the configuration of an intake and exhaust system according to a first modified example. [Figure 4]FIG. 4 is a schematic diagram showing the configuration of an intake and exhaust system according to a second modified example. [Figure 5] FIG. 5 is a schematic diagram showing the configuration of an intake and exhaust system according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and, unless otherwise specified, do not limit the present disclosure. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0015] Fig. 1 is a schematic diagram showing the configuration of an intake and exhaust system 1 according to this embodiment. The intake and exhaust system 1 is a system related to the intake and exhaust of an engine 100. As shown in Fig. 1, the intake and exhaust system 1 includes the engine 100, an intake passage 200, an exhaust passage 300, a supercharger 400, a connection passage 500, a reflux supercharger 600, and a control device 700.

[0016] Engine 100 has multiple cylinders. In the example of FIG. 1, engine 100 has a first cylinder #1, a second cylinder #2, a third cylinder #3, a fourth cylinder #4, a fifth cylinder #5, and a sixth cylinder #6. However, the number of cylinders in engine 100 may be other than six. FIG. 2 is a schematic diagram showing the configuration of each cylinder of engine 100 according to this embodiment. In FIG. 2, intake port 104a, exhaust port 104b, fuel injection valve 112, and ignition device 114 are illustrated on the same cross section. However, intake port 104a, exhaust port 104b, fuel injection valve 112, and ignition device 114 do not have to be located on the same cross section.

[0017] 2, the engine 100 includes a cylinder liner 102, a cylinder head 104, and a piston 106. The piston 106 is housed within the cylinder liner 102. The cylinder liner 102, the cylinder head 104, and the piston 106 form a combustion chamber 108.

[0018] An intake port 104a and an exhaust port 104b are formed in the cylinder head 104. The intake port 104a and the exhaust port 104b open to the combustion chamber 108. The intake valve 110a opens and closes the opening of the intake port 104a on the combustion chamber 108 side. The exhaust valve 110b opens and closes the opening of the exhaust port 104b on the combustion chamber 108 side. The opening and closing operations of the intake valve 110a and the exhaust valve 110b are performed in accordance with the rotation of a camshaft (not shown).

[0019] A pipe that forms a branch passage 202 of an intake passage 200 (described later) is connected to the intake port 104a. An air-fuel mixture flows into the combustion chamber 108 via the intake port 104a. A pipe that forms a branch passage 302 of an exhaust passage 300 (described later) is connected to the exhaust port 104b. Exhaust gas is discharged from the combustion chamber 108 via the exhaust port 104b.

[0020] The fuel injection valve 112 is connected to a fuel supply source. The fuel supply source is, for example, a fuel tank (not shown) or a pipeline for city gas or the like. The fuel injection valve 112 is provided in a branch flow path 202 of the intake flow path 200. The tip of the fuel injection valve 112 faces the intake port 104a. The fuel injection valve 112 injects fuel gas into the intake port 104a. The fuel gas is generated, for example, by gasifying LNG (liquefied natural gas). The fuel gas is not limited to LNG, and may be, for example, gasified LPG (liquefied petroleum gas), light oil, heavy oil, ammonia, hydrogen, or the like. The engine 100 is a gas engine that uses fuel gas as fuel. Hereinafter, fuel gas may also be simply referred to as fuel.

[0021] The ignition device 114 is provided in the cylinder head 104. The tip of the ignition device 114 protrudes into the combustion chamber .

[0022] The engine 100 is a four-stroke engine. During the intake stroke, fuel is injected from the fuel injector 112, the intake valve 110a opens, and the exhaust valve 110b closes. As the piston 106 moves toward bottom dead center, intake air and fuel are drawn into the combustion chamber 108 through the intake port 104a. During the compression stroke, the intake valve 110a and the exhaust valve 110b close. As the piston 106 moves toward top dead center, the air-fuel mixture in the combustion chamber 108 is compressed. The air-fuel mixture is ignited and combusted by the ignition device 114, and during the combustion stroke, the piston 106 is pressed toward the bottom dead center. During the exhaust stroke, the intake valve 110a closes and the exhaust valve 110b opens. As the piston 106 moves toward top dead center, the burned exhaust gas is discharged from the combustion chamber 108 through the exhaust port 104b. Returning to Figure 1, the explanation will be continued below.

[0023] The intake flow path 200 communicates with the combustion chambers 108 of the engine 100. Intake air, which is air supplied to the combustion chambers 108, flows through the intake flow path 200. An intake port (not shown) is provided at the upstream end of the intake flow path 200, through which air is taken in from the outside. The intake flow path 200 has a plurality of branch flow paths 202 that communicate with the plurality of combustion chambers 108, respectively. The plurality of branch flow paths 202 are provided downstream of the intake flow path 200. As described above, the piping that forms the branch flow paths 202 is connected to the intake port 104a of the engine 100. The intake port 104a corresponds to the downstream end of the branch flow paths 202. The intake port 104a is included in the intake flow path 200.

[0024] The exhaust flow path 300 communicates with the combustion chambers 108 of the engine 100. Exhaust gas discharged from the combustion chambers 108 flows through the exhaust flow path 300. An exhaust port (not shown) is provided at the downstream end of the exhaust flow path 300, through which the exhaust gas is discharged to the outside. The exhaust flow path 300 has a plurality of branch flow paths 302 that communicate with the plurality of combustion chambers 108, respectively. The plurality of branch flow paths 302 are provided on the upstream side of the exhaust flow path 300. As described above, the pipe that forms the branch flow path 302 is connected to the exhaust port 104b of the engine 100. The exhaust port 104b corresponds to the upstream end of the branch flow path 302. The exhaust port 104b is included in the exhaust flow path 300.

[0025] The supercharger 400 has a compressor 402 and a turbine 404. The impeller of the compressor 402 and the impeller of the turbine 404 rotate as a unit. The impeller of the compressor 402 and the impeller of the turbine 404 are connected by a shaft. The supercharger 400 corresponds to an example of a second supercharger. The compressor 402 corresponds to an example of a second compressor. The turbine 404 corresponds to an example of a second turbine.

[0026] The compressor 402 is provided in the intake air flow path 200, upstream of the branch flow path 202. The compressor 402 compresses the intake air taken in through the intake port and sends it downstream. An intercooler C1 is provided in the intake air flow path 200, upstream of the branch flow path 202 and downstream of the compressor 402. The intake air flowing through the intercooler C1 is cooled by heat exchange with air outside the intercooler C1. The intake air that has passed through the intercooler C1 is sent to each combustion chamber 108 via each branch flow path 202. Note that the intercooler C1 may also be one that uses cooling water, such as engine cooling water or industrial water, to cool the intake air.

[0027] The turbine 404 is provided in the exhaust flow path 300 downstream of the branch flow paths 302. The exhaust gas discharged from the engine 100 is sent to the turbine 404 via each branch flow path 302. The exhaust gas sent to the turbine 404 passes through the turbine 404 and is discharged from an exhaust port. The turbine 404 generates rotational power when an impeller of the turbine 404 is rotated by the exhaust gas. The rotational power generated by the turbine 404 is transmitted to the compressor 402 via a shaft.

[0028] The connection flow path 500 connects the first portion P1 and the second portion P2 of the intake flow path 200. As will be described later, the connection flow path 500 is provided to return fuel remaining in the intake port 104a of the engine 100 to another location in the intake flow path 200. In the connection flow path 500, gas flows from the first portion P1 to the second portion P2. Hereinafter, the upstream side of the connection flow path 500 refers to the first portion P1 side, and the downstream side of the connection flow path 500 refers to the second portion P2 side.

[0029] In the example of FIGS. 1 and 2, the intake port 104a of each cylinder corresponds to the first portion P1. In the example of FIGS. 1 and 2, the portion of the intake passage 200 upstream of the branch passage 202 and downstream of the intercooler C1 corresponds to the second portion P2. A plurality of branch passages 502 are provided upstream of the connection passage 500. Each branch passage 502 is connected to the intake port 104a of each cylinder. An on-off valve V1 is provided in each branch passage 502. The on-off valve V1 is capable of opening and closing the branch passage 502. The downstream end of the connection passage 500 is connected to the portion of the intake passage 200 upstream of the branch passage 202 and downstream of the intercooler C1. However, the positions of the first portion P1 and the second portion P2 in the intake passage 200 are not limited to those in the example of FIGS. 1 and 2, as will be described later. 1 and 2, the second portion P2 is located upstream of the first portion P1 in the intake flow path 200. However, the positional relationship between the first portion P1 and the second portion P2 in the intake flow path 200 is not limited to the example in FIGS. 1 and 2, as will be described later.

[0030] The reflux supercharger 600 has a compressor 602 and a turbine 604. The impeller of the compressor 602 and the impeller of the turbine 604 rotate as a unit. The impeller of the compressor 602 and the impeller of the turbine 604 are connected by a shaft. The reflux supercharger 600 is provided to realize the reflux of gas via the connecting flow path 500. The reflux supercharger 600 corresponds to an example of a first supercharger. The compressor 602 corresponds to an example of a first compressor. The turbine 604 corresponds to an example of a first turbine.

[0031] The compressor 602 is provided in the connecting flow path 500 downstream of the branch flow path 502. As will be described later, the impeller of the compressor 602 is rotationally driven using rotational power obtained by rotating the impeller of the turbine 604. The compressor 602 compresses the gas in the connecting flow path 500 and sends it downstream. Therefore, gas is drawn from the first portion P1 of the intake flow path 200 into the connecting flow path 500 through the branch flow path 502 whose on-off valve V1 is open. In other words, gas is drawn into the connecting flow path 500 from the intake port 104a.

[0032] Here, when the intake valve 110a is closed, some of the fuel injected from the fuel injection valve 112 may remain in the intake port 104a. In such a case, the fuel remaining in the intake port 104a can be sent to the connection flow path 500 by suctioning gas into the connection flow path 500. Specifically, the fuel remaining in the intake port 104a can be sent to the connection flow path 500 by opening the opening / closing valve V1 of the branch flow path 502 connected to the intake port 104a of the cylinder whose intake valve 110a is closed. This suppresses blow-by, in which unburned fuel is discharged through the exhaust port 104b when both the intake valve 110a and the exhaust valve 110b are open during the switch from the exhaust stroke to the intake stroke.

[0033] As described above, the compressor 602 corresponds to an example of a gas delivery unit that delivers gas from the first portion P1 to the second portion P2. However, as will be described later, a unit other than the compressor 602 of the reflux turbocharger 600 may be used as the gas delivery unit.

[0034] An intercooler C2 is provided in the connecting flow path 500 downstream of the compressor 602. The gas flowing through the intercooler C2 is cooled by heat exchange with the air outside the intercooler C2. The gas that has passed through the intercooler C2 is sent to the second portion P2 of the intake flow path 200. Note that the intercooler C2 may also be one that uses cooling water, such as engine cooling water or industrial water, to cool the intake air.

[0035] The turbine 604 is provided in the exhaust flow path 300 downstream of the turbine 404. The exhaust flow path 300 branches into a branch flow path 304 and a branch flow path 306 downstream of the turbine 404. The downstream ends of the branch flow path 304 and the branch flow path 306 merge. The turbine 604 is provided in the branch flow path 306. The exhaust gas sent to the turbine 404 is divided and sent to the branch flow path 304 and the branch flow path 306. The turbine 604 generates rotational power when the impeller of the turbine 604 is rotated by the exhaust gas sent to the branch flow path 306. The rotational power generated by the turbine 604 is transmitted to the compressor 602 via a shaft. The flow rate of the exhaust gas in each of the branch flow paths 304 and 306 can be adjusted using, for example, a flow control valve or the like.

[0036] The control device 700 includes a central processing unit (CPU), a ROM storing programs and the like, a RAM as a work area, and the like. The control device 700 controls the operation of each device in the intake and exhaust system 1. For example, the control device 700 controls the operation of the engine 100. For example, the control device 700 controls the operation of the on-off valve V1. Specifically, the control device 700 opens the on-off valve V1 of the branch passage 502 connected to the intake port 104a of the cylinder whose intake valve 110a is closed. On the other hand, the control device 700 closes the on-off valve V1 of the branch passage 502 connected to the intake port 104a of the cylinder whose intake valve 110a is open.

[0037] As described above, in the intake and exhaust system 1, the first portion P1 and the second portion P2 of the intake flow path 200 are connected by the connection flow path 500. The connection flow path 500 is provided with the compressor 602 as a gas delivery section. This allows the fuel remaining in the intake port 104a to be sent to the connection flow path 500. This prevents unburned fuel from being discharged through the exhaust port 104b, thereby improving thermal efficiency and reducing greenhouse gas emissions.

[0038] Furthermore, in the intake and exhaust system 1, the gas delivery section provided in the connecting flow path 500 is the compressor 602 of the reflux supercharger 600. In the reflux supercharger 600, the impeller of the turbine 604 is rotated by the gas flow in the intake and exhaust system 1, thereby driving the impeller of the compressor 602 to rotate. Therefore, the gas flow in the intake and exhaust system 1 can be used to deliver the gas in the connecting flow path 500. This allows the fuel remaining in the intake port 104a to be delivered to the connecting flow path 500 in an appropriate manner.

[0039] However, the gas delivery unit provided in the connection flow path 500 may be something other than the compressor 602 of the reflux turbocharger 600. For example, a gas delivery unit driven by electricity, such as an electric fan or an electric compressor, may be provided in the connection flow path 500.

[0040] Furthermore, in the intake and exhaust system 1, the turbine 604 of the recirculation turbocharger 600 is provided in the exhaust passage 300. As a result, the impeller of the compressor 602 is rotationally driven appropriately by utilizing the flow of exhaust gas flowing through the exhaust passage 300. Therefore, the gas in the connection passage 500 is sent appropriately by utilizing the flow of exhaust gas. In particular, the turbine 604 is provided in the branch passage 306 of the exhaust passage 300. As a result, a portion of the exhaust gas flowing through the exhaust passage 300 is sent to the turbine 604, thereby suppressing over-rotation of the turbine 604. However, the turbine 604 may be provided at a location other than the exhaust passage 300, as will be described later.

[0041] Furthermore, in the intake and exhaust system 1, an intercooler C2 is provided in the connection passage 500. This allows the high-temperature gas sent out by the compressor 602 to be cooled in the connection passage 500. This prevents the high-temperature gas containing fuel from being returned to the intake passage 200, thereby preventing abnormal combustion. However, the intercooler C2 does not necessarily have to be provided.

[0042] Furthermore, in the intake and exhaust system 1, an on-off valve V1 is provided in each branch passage 502. This allows the timing of sending fuel remaining in the intake port 104a to the connection passage 500 to be optimized for each cylinder. For example, for a cylinder in which the intake valve 110a is open, it is possible to prevent unnecessary fuel from being sent from the intake port 104a to the connection passage 500. However, the on-off valve V1 does not necessarily have to be provided.

[0043] In the above example, the intake port 104a corresponds to the first portion P1 of the intake passage 200. However, the position of the first portion P1 in the intake passage 200 is not limited to the above example. Here, from the viewpoint of effectively sending fuel remaining in the intake port 104a to the connection passage 500, it is preferable that the first portion P1 be as close to the intake port 104a as possible. However, if the first portion P1 is the intake port 104a, the connection passage 500 needs to pass through the cylinder head 104. If it is difficult to pass the connection passage 500 through the cylinder head 104 due to design considerations, for example, the first portion P1 may be a portion of the branch passage 202 of the intake passage 200 that is outside the cylinder head 104. In this case, the first portion P1 may be closer to the cylinder head 104 than the fuel injection valve 112, or may be on the opposite side of the cylinder head 104 than the fuel injection valve 112.

[0044] In the above example, the second portion P2 corresponds to the portion of the intake passage 200 upstream of the branch passage 202 and downstream of the intercooler C1. However, the position of the second portion P2 in the intake passage 200 is not limited to the above example. Here, fuel is returned to the second portion P2 of the intake passage 200 via the connecting passage 500, so from the viewpoint of suppressing flashback, it is desirable that the second portion P2 be as close as possible to the engine 100. However, the second portion P2 may be, for example, the portion of the intake passage 200 upstream of the intercooler C1 and downstream of the compressor 402.

[0045] Furthermore, the second portion P2 may be disposed in each branch passage 202, for example. In this case, in the flow direction of the intake passage 200, the second portion P2 may be located upstream of the first portion P1, downstream of the first portion P1, or at a flow direction position substantially coincident with the flow direction position of the first portion P1. Here, there is a time lag between the timing at which the fuel remaining in the intake port 104a is sent from the first portion P1 to the connection passage 500 and the timing at which the fuel sent to the connection passage 500 reaches the second portion P2. In other words, the fuel does not immediately reach the second portion P2 after being sent from the first portion P1 to the connection passage 500. Therefore, even if the second portion P2 is not located upstream of the first portion P1, sending the fuel remaining in the intake port 104a to the connection passage 500 suppresses blow-by of unburned fuel.

[0046] The intake and exhaust systems according to the respective modifications will be described below with reference to FIGS.

[0047] Fig. 3 is a schematic diagram showing the configuration of an intake and exhaust system 1A according to a first modified example. As shown in Fig. 3, the intake and exhaust system 1A according to the first modified example differs from the intake and exhaust system 1 described above in the arrangement of the turbine 604 of the reflux turbocharger 600.

[0048] As shown in FIG. 3, in the intake and exhaust system 1A, the upstream and downstream sides of the turbine 404 in the exhaust flow path 300 are connected by a wastegate flow path 308. The wastegate flow path 308 is included in the exhaust flow path 300. A wastegate valve V2 is provided in the wastegate flow path 308. The wastegate flow path 308 corresponds to an example of a first wastegate flow path. The wastegate valve V2 corresponds to an example of a first wastegate valve.

[0049] By adjusting the opening degree of the wastegate valve V2, it is possible to adjust the flow rate of exhaust gas flowing through the wastegate flow path 308. This adjusts the flow rate of exhaust gas passing through the turbine 404, thereby suppressing, for example, over-rotation of the turbine 404. The operation of the wastegate valve V2 is controlled by the control device 700.

[0050] In the intake and exhaust system 1A, the turbine 604 of the reflux turbocharger 600 is provided in the wastegate flow path 308. As a result, the impeller of the turbine 604 is rotated by the exhaust gas flowing through the wastegate flow path 308, which in turn drives the impeller of the compressor 602 to rotate. Therefore, the gas in the connection flow path 500 is appropriately discharged by utilizing the flow of the exhaust gas flowing through the wastegate flow path 308. Therefore, similar to the intake and exhaust system 1 described above, blow-by, in which unburned fuel is discharged through the exhaust port 104b, is suppressed.

[0051] Fig. 4 is a schematic diagram showing the configuration of an intake and exhaust system 1B according to a second modified example. As shown in Fig. 4, the intake and exhaust system 1B according to the second modified example differs from the intake and exhaust system 1 described above in the arrangement of the turbine 604 of the reflux turbocharger 600.

[0052] As shown in FIG. 4 , in the intake and exhaust system 1B, the downstream and upstream sides of the compressor 402 in the intake passage 200 are connected by a return passage 204. A portion of the intake air sent out from the compressor 402 passes through the return passage 204 and is returned to the upstream side of the compressor 402. The return passage 204 is included in the intake passage 200. A turbine 604 is provided in the return passage 204. The turbine 604 generates rotational power when an impeller of the turbine 604 is rotated by the intake air sent to the return passage 204. The rotational power generated by the turbine 604 is transmitted to the compressor 602 via a shaft. Note that the downstream end of the return passage 204, through which the intake air flows, may be connected to the exhaust passage 300 on the downstream side of the turbine 404. In this case, the intake air that has passed through the turbine 604 is sent to the exhaust passage 300 on the downstream side of the turbine 404.

[0053] As described above, in the intake and exhaust system 1B, the turbine 604 of the recirculation turbocharger 600 is provided in the intake air passage 200. As a result, the impeller of the turbine 604 is rotated by the intake air flowing through the intake air passage 200, which in turn rotates the impeller of the compressor 602. Therefore, the gas in the connection passage 500 is appropriately discharged by utilizing the flow of the intake air. Therefore, similar to the intake and exhaust system 1 described above, blow-by, in which unburned fuel is discharged through the exhaust port 104b, is suppressed.

[0054] As in the above-described intake and exhaust system 1, the turbine 604 of the reflux turbocharger 600 may be provided in the exhaust passage 300. In this case, the impeller of the turbine 604 is rotated by high-temperature gas, and therefore the rotational power transmitted to the impeller of the compressor 602 can be increased, compared to when the turbine 604 is provided in the intake passage 200. On the other hand, when the turbine 604 is provided in the intake passage 200, as in the intake and exhaust system 1B, the heat resistance of the turbine 604 can be lowered, compared to when the turbine 604 is provided in the exhaust passage 300.

[0055] In the above, an example has been described in which the turbine 604 is provided downstream of the compressor 402 and upstream of the intercooler C1 in the intake passage 200. However, the turbine 604 may also be provided downstream of the intercooler C1 in the intake passage 200.

[0056] Fig. 5 is a schematic diagram showing the configuration of an intake and exhaust system 1C according to a third modified example. As shown in Fig. 5, the intake and exhaust system 1C according to the third modified example differs from the intake and exhaust system 1 described above in that a wastegate flow path 800 is added.

[0057] As shown in Fig. 5, in the intake and exhaust system 1C, the upstream and downstream sides of the turbine 604 in the branch passage 306, which is a passage in which the turbine 604 is provided, are connected by a wastegate passage 800. A wastegate valve V3 is provided in the wastegate passage 800. The wastegate passage 800 corresponds to an example of a second wastegate passage. The wastegate valve V3 corresponds to an example of a second wastegate valve.

[0058] As described above, in the intake and exhaust system 1C, compared to the above-described intake and exhaust system 1, a wastegate passage 800 in which a wastegate valve V3 is provided is added. As a result, the flow rate of exhaust gas flowing through the wastegate passage 800 can be adjusted by adjusting the opening degree of the wastegate valve V3. This adjusts the flow rate of exhaust gas passing through the turbine 604, thereby suppressing over-rotation of the turbine 604. The operation of the wastegate valve V3 is controlled by the control device 700. Note that the flow rate of exhaust gas in each of the branch passages 304 and 306 can be adjusted using, for example, a flow rate adjustment valve (not shown) or the like.

[0059] In the above, a case has been described in which the turbine 604 of the recirculation turbocharger 600 is provided in the exhaust passage 300. However, when the turbine 604 is provided in the intake passage 200, the wastegate passage 800 may be provided. In this case, the upstream side and downstream side of the turbine 604 in the intake passage 200, which is the passage in which the turbine 604 is provided, are connected by the wastegate passage 800 in which a wastegate valve V3 is provided. Then, by adjusting the opening degree of the wastegate valve V3, it is possible to adjust the flow rate of the intake air flowing through the wastegate passage 800. This adjusts the flow rate of the intake air passing through the turbine 604, thereby suppressing over-rotation of the turbine 604.

[0060] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure. [Explanation of symbols]

[0061] 1. Intake and exhaust system 1A Intake and Exhaust System 1B intake and exhaust system 1C intake and exhaust system 100 Engine 108 Combustion chamber 112 Fuel injection valve 200 intake passage 300 Exhaust passage 308 Wastegate passage (1st wastegate passage) 400 turbocharger (second turbocharger) 402 Compressor (Second Compressor) 404 Turbine (2nd Turbine) 500 connecting channels 600 Reflux turbocharger (first turbocharger) 602 Compressor (first compressor, gas delivery section) 604 Turbine (No. 1 Turbine) 800 Wastegate passage (second wastegate passage) P1 Part 1 P2 2nd part V2 Wastegate valve (first wastegate valve) V3 Wastegate valve (second wastegate valve)

Claims

1. An engine having a plurality of cylinders, each cylinder having a combustion chamber, an intake port and an exhaust port opening into said combustion chamber, an intake valve for opening and closing said intake port, and an exhaust valve for opening and closing said exhaust port; an intake passage having a plurality of first branch passages respectively communicating with the plurality of combustion chambers, the intake passage being provided with a fuel injection valve; a connecting flow path connecting the first portion and the second portion of the intake flow path; a gas delivery section provided in the connection flow path and configured to deliver gas from the first section toward the second section; Equipped with the first portion is each of the plurality of first branch flow paths, the connecting flow path has a plurality of second branch flow paths connected to the plurality of first branch flow paths, respectively; an on-off valve is provided in each of the plurality of second branch flow paths, a control device that opens the on-off valve of the second branch flow path connected to the intake port of the cylinder whose intake valve is closed, and closes the on-off valve of the second branch flow path connected to the intake port of the cylinder whose intake valve is open, Engine intake and exhaust system.

2. a first turbocharger including a first turbine and a first compressor provided in the connecting flow path; The gas delivery unit is the first compressor.

2. The engine intake and exhaust system according to claim 1.

3. an exhaust passage communicating with the combustion chamber; The first turbine is provided in the exhaust flow path.

3. The engine intake and exhaust system according to claim 2.

4. a second turbocharger including a second turbine provided in the exhaust passage and a second compressor provided in the intake passage, the exhaust flow path includes a first wastegate flow path that connects an upstream side and a downstream side of the second turbine in the exhaust flow path and is provided with a first wastegate valve; The first turbine is provided in the first wastegate flow path.

4. The engine intake and exhaust system according to claim 3.

5. The first turbine is provided in the intake flow path.

3. The engine intake and exhaust system according to claim 2.

6. an upstream side and a downstream side of the first turbine in the flow path in which the first turbine is provided are connected by a second wastegate flow path in which a second wastegate valve is provided; 6. An intake and exhaust system for an engine according to claim 2, 3 or 5.

Images