JP2009287434A - Exhaust recirculation device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust recirculation device for an internal combustion engine capable of appropriately achieving high supercharging by means of, for example, a twin scroll type turbocharger. <P>SOLUTION: The exhaust recirculation device (10) for an internal combustion engine includes, in its exhaust system, the turbocharger (100 or the like) having a turbine, a first exhaust passage (209) including a first confluence portion (209a) where first exhaust gas from a first cylinder group (#1 and #4) joins and introducing the first exhaust gas to the turbocharger, a second exhaust passage (210) including a second confluence portion (210a) where second exhaust gas from a second cylinder group (#3 and #4) joins and introducing the second exhaust gas to the turbocharger, a first scroll section (121) for introducing the first exhaust gas from the first exhaust passage to the turbine (170), a second scroll section (122) for introducing the second exhaust gas from the second exhaust passage to the turbine, a first bypass passage (131) for causing the first exhaust gas introduced to the first scroll section to bypass the turbine and also communicating with an EGR passage (310) for recirculating the first exhaust gas as EGR gas to an intake system, and a second bypass passage (132) for causing the second exhaust gas to bypass the turbine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technical field of an exhaust gas recirculation device for an internal combustion engine such as an EGR (Exhaust Gas Recirculation) device.

  As an exhaust gas recirculation device of this type of internal combustion engine, in order to suppress the occurrence of knocking in an operation region where the exhaust gas exhausted through the waste gate valve is recirculated to EGR gas or in a high-load operation region of a gasoline engine. Has been proposed to recirculate external EGR gas (see, for example, Patent Document 1).

  Further, as an exhaust gas recirculation device of this type of internal combustion engine, EGR gas is extracted from turbine scroll passages that are continuously connected to exhaust manifolds partitioned by partition walls so that exhaust interference of each cylinder does not occur. There has been proposed one that reduces the cross-sectional area of the channel on the side (see, for example, Patent Document 2).

  Further, as an exhaust gas recirculation device for this type of internal combustion engine, an exhaust manifold is divided for each cylinder group in which the exhaust strokes do not overlap, and a turbocharger is provided at the junction of these exhaust manifolds. One provided with an EGR gas attachment port has been proposed (see, for example, Patent Document 3).

  In addition, for example, when high supercharging is performed by a turbocharger under a condition where a downsizing concept is recommended, knocking is assumed to occur particularly in a state where the speed of the internal combustion engine is low. The For this reason, in order to avoid the occurrence of knocking, it is necessary to shift the ignition timing to the delay side (that is, the top dead center side of the compression stroke). However, since the ignition timing shifts to the top dead center side of the compression stroke, it is necessary to ignite in a state where the in-cylinder pressure (that is, the gas pressure in the combustion chamber) is increased. As a result, the voltage required for ignition is reduced. It will be high. For this reason, if the voltage required for ignition cannot be maintained due to some factor, a technical problem that ignition cannot be performed may occur. Thus, a method has been proposed in which the ignition timing is changed to the advance side by recirculating the EGR gas as disclosed in Patent Documents 1 to 3 described above in the entire operation region where supercharging is performed.

Japanese Patent Laid-Open No. 2001-073884 JP 2005-344676 A JP 2007-064042 A

  However, when high supercharging is performed in the above-described twin scroll type supercharger (see, for example, Patent Document 2), the heat load of the exhaust system increases. For this reason, in order to reduce the influence of the increase in the heat load in the catalyst (so-called Start Catalyst) that purifies the harmful gas in the exhaust when it is cold immediately after the engine is started, it becomes necessary to bypass the catalyst. Alternatively, in order to reduce the residual gas, a means for reducing the pressure loss of the muffler is required. For this reason, in the conventional method of recirculating EGR gas from the downstream side of the turbocharger turbine section to the intake system in order to suppress exhaust interference, the exhaust pressure in the intake system is more than the exhaust pressure downstream of the turbocharger turbine section. A technical problem arises that the supply pressure becomes higher and it becomes difficult to recirculate the EGR gas.

  Accordingly, the present invention has been made in view of the above-mentioned problems, for example, and provides an exhaust gas recirculation device for an internal combustion engine that can realize high supercharging more appropriately in, for example, a twin scroll type supercharger. The task is to do.

  In order to solve the above problems, an exhaust gas recirculation apparatus for an internal combustion engine according to the present invention has a turbine in an exhaust system of an internal combustion engine having a plurality of cylinders and performs supercharging in the intake system of the internal combustion engine. And a first merging portion where the first exhaust from the first cylinder group of the plurality of cylinders merges, and the first exhaust is guided to the supercharger via the first merging portion. The exhaust passage includes a second merging portion where second exhaust from the second cylinder group among the plurality of cylinders merges, and guides the second exhaust to the supercharger via the second merging portion. A second scroll passage, a first scroll portion for continuously guiding the first exhaust from the first exhaust passage to the turbine, and a second for continuously guiding the second exhaust from the second exhaust passage to the turbine. A scroll portion and the first exhaust led to the first scroll portion. In addition to being able to bypass the turbine and be introduced downstream from the turbine, an EGR passage that recirculates a part of the first exhaust gas guided to the first scroll portion to the intake system as EGR gas And a first bypass passage communicating with the upstream side of the turbine, and the second exhaust gas guided to the second scroll part can bypass the turbine and be introduced downstream from the turbine. A detour passage.

  The “internal combustion engine” according to the present invention has one or a plurality of cylinders, and an air-fuel mixture that is a mixture of fuel such as gasoline, light oil or various alcohols and intake air in each of the cylinders. It is a concept that encompasses an engine that is configured to be able to take out the power generated when it burns, for example, through a mechanical transmission path such as a piston, a connecting rod, and a crankshaft, for example, This refers to a 2-cycle or 4-cycle reciprocating engine.

  According to the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the first exhaust passage includes a first merging portion where the first exhaust from the first cylinder group among the plurality of cylinders merges. In addition, the first exhaust passage is guided to the supercharger via the first junction by the first exhaust passage. The second exhaust passage includes a second merging portion where the second exhaust from the second cylinder group among the plurality of cylinders merges. In addition, the second exhaust passage guides the second exhaust to the supercharger via the second junction. As a result, the first exhaust of the first cylinder group and the second exhaust of the second cylinder group are respectively guided to the supercharger via the first and second merging portions described above. It is possible to effectively suppress the occurrence of exhaust interference in which one exhaust and the second exhaust of the second cylinder group collide with each other to reduce the flow speed of the exhaust. As a result, an increase in exhaust pressure due to exhaust interference can be suppressed, and the first exhaust and the second exhaust can be discharged appropriately and quickly. It is possible to effectively suppress the combustion failure of the fuel, and to effectively suppress the deterioration of fuel consumption. If the exhaust gas from a plurality of cylinders merges into one merging section, the exhaust gas discharged from each of the plurality of cylinders collides with each other, and the degree of occurrence of exhaust interference that reduces the flow speed of the exhaust gas increases. This raises a technical problem that exhaust from a plurality of cylinders is not smoothly discharged.

  The first scroll portion continuously guides the first exhaust gas from the first exhaust passage to the turbine. The second scroll continuously guides the second exhaust from the second exhaust passage to the turbine.

  The first bypass passage can introduce the first exhaust gas guided to the first scroll portion to the downstream side of the turbine while bypassing the turbine. The second bypass passage can introduce the second exhaust gas guided to the second scroll portion to the downstream side of the turbine while bypassing the turbine. As a result, the flow rates of the first exhaust gas and the second exhaust gas guided to the turbine and the flow rates of the first exhaust gas and the second exhaust gas bypassing the turbine can be changed, and the supercharging pressure and exhaust pressure of the intake system can be changed. Can be set to an appropriate value. Thereby, the compression ratio in the cylinder can be set to an appropriate value, combustion failure in the cylinder such as knocking can be effectively suppressed, and deterioration of fuel consumption can be effectively suppressed. .

  In particular, the first bypass passage communicates with an EGR passage that recirculates a part of the first exhaust gas guided to the first scroll portion as EGR gas to the intake system on the upstream side of the turbine. Here, the “EGR passage” according to the present invention is a passage that branches from an exhaust system as a concept that may appropriately include, for example, an exhaust port, an exhaust manifold, an exhaust pipe, and the like, and recirculates part of the exhaust to the intake system. means. Qualitatively speaking, the EGR gas is somewhat mixed with the intake air supplied to the intake system, and thus includes, for example, NOx or the like (PM (Particulate Matter: particulate matter) depending on the form of the internal combustion engine). ), The generation of various target substances is somewhat suppressed. Typically, the EGR passage is preferably provided with a cooling system for cooling the recirculated exhaust gas in order to reduce the expansion of the exhaust gas.

  As a result, compared with the case where the first bypass passage communicates with the EGR passage on the downstream side of the turbine, the EGR gas is recirculated and supplied to the intake system in a state higher than the supercharging pressure of the intake system. Therefore, EGR gas can be supplied at a more appropriate pressure.

  As a result, (i) effective suppression of the occurrence of exhaust interference, (ii) appropriate adjustment of the ratio of supercharging pressure and exhaust pressure in the intake system, and (iii) appropriate supply pressure of EGR gas It is possible to more appropriately realize the balance between the three adjustments. As a result, the EGR gas cooled more effectively can reduce the temperature of the intake air, and the intake air that is reduced in temperature increases the amount of intake air that is drawn into the cylinder. The output can be improved.

  In one aspect of the exhaust gas recirculation device for an internal combustion engine according to the present invention, the length of the flow path between one cylinder (for example, cylinder # 1) included in the first cylinder group and the first merging portion is: It is larger than the length of the flow path between another cylinder (for example, cylinder # 2) included in the second cylinder group and the second merging portion.

  According to this aspect, the time until the first exhaust from the first cylinder group is merged can be made longer than the time until the second exhaust from the second cylinder group is merged. Accordingly, the oxygen contained in the exhaust gas by causing the first exhaust gas to burn in an exhaust system other than the combustion chamber of the cylinder (so-called afterburning) in a larger amount than the second exhaust gas, and the first exhaust gas merges. Can be effectively suppressed. As a result, the temperature of the first exhaust led to the EGR passage via the first exhaust passage, the first scroll portion, and the first bypass passage is guided to the second exhaust passage, the second scroll portion, and the second bypass passage. It can be made lower than the temperature of the second exhaust.

  As a result, the thermal load applied to the cooling system provided in the EGR passage can be effectively reduced. As a result, it is possible to reduce the temperature of the intake air by the EGR gas cooled more effectively. Since the intake air that has been reduced in temperature increases the amount of intake air taken into the cylinder, The output can be improved.

  Temporarily, the length of the flow path between one cylinder included in the first cylinder group and the first merging portion is set to the length of the flow path between the other cylinders included in the second cylinder group and the second merging portion. When the length is smaller than the length, the time until the first exhaust from the first cylinder group merges is shorter than the time until the second exhaust from the second cylinder group merges. For this reason, since the afterburning of the first exhaust is performed in a smaller amount than the afterburning of the second exhaust, the oxygen contained in the exhaust increases when the first exhaust joins, and the first exhaust The combustion reaction of afterburning after merging becomes active. Therefore, the temperature of the first exhaust led to the EGR passage via the first exhaust passage, the first scroll portion, and the first bypass passage is guided to the second exhaust passage, the second scroll portion, and the second bypass passage. The temperature becomes higher than the temperature of the second exhaust, and the heat load applied to the cooling system of the EGR passage increases.

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, a flow passage cross-sectional area of the first bypass passage is smaller than a flow passage cross-sectional area of the second bypass passage.

  According to this aspect, in the first bypass passage where the exhaust pressure tends to be lower than that of the second bypass passage by communicating with the EGR passage, the exhaust pressure of the first bypass passage is determined according to the cross-sectional area of the flow path. Can be increased. Thereby, the difference between the exhaust pressure of the first bypass passage and the exhaust pressure of the second bypass passage can be effectively reduced. As a result, the difference between the pressure in the cylinder of the first cylinder group that discharges the first exhaust gas to the first bypass path and the pressure in the cylinder of the second cylinder group that discharges the second exhaust gas to the second bypass path is effective. Can be reduced. As a result, the difference between the residual gas amount in the cylinders of the first cylinder group and the residual gas amount in the cylinders of the second cylinder group can be effectively reduced. The difference between the combustion state and the combustion state in the cylinders of the second cylinder group can be effectively reduced.

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the flow path cross-sectional area of the first bypass passage and the flow path cross-sectional area of the second bypass path are operations in which the load of the internal combustion engine is maximum. Under the state, the exhaust flow rate flowing through the first scroll portion and the exhaust flow rate flowing through the second scroll portion are set to be equal.

  According to this aspect, in general, the residual gas amount in the cylinders of the first cylinder group that supplies the first exhaust to the first exhaust passage, the first scroll portion, and the first bypass passage, the second exhaust passage, The difference from the residual gas amount in the cylinders of the second cylinder group that supplies the second exhaust gas to the two scroll portions and the second bypass passage increases as the load (typically, the intake air amount) of the internal combustion engine increases. Become. Therefore, according to this aspect, the difference between the residual gas amount in the cylinders of the first cylinder group and the residual gas amount in the cylinders of the second cylinder group is determined in a wide range of the load of the internal combustion engine. The difference between the residual gas amount in the cylinder and the residual gas amount in the cylinders of the second cylinder group can be reduced more effectively. As a result, the combustion state in the cylinders of the first cylinder group and the second cylinder group can be reduced. The difference from the combustion state in the cylinder can be reduced more effectively.

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the first bypass passage and the second bypass passage can be blocked by a valve body, and the first opening of the valve body in the first bypass passage is provided. The area is smaller than the second opening area of the valve body in the second bypass passage.

  According to this aspect, the exhaust pressure of the first bypass passage is reduced according to the first opening area in the first bypass passage in which the exhaust pressure tends to decrease more than the second bypass passage by communicating with the EGR passage. Can be increased. Thereby, the difference between the exhaust pressure of the first bypass passage and the exhaust pressure of the second bypass passage can be effectively reduced. As a result, the difference between the pressure in the cylinder of the first cylinder group that discharges the first exhaust gas to the first bypass path and the pressure in the cylinder of the second cylinder group that discharges the second exhaust gas to the second bypass path is effective. Can be reduced. As a result, the difference between the residual gas amount in the cylinders of the first cylinder group and the residual gas amount in the cylinders of the second cylinder group can be effectively reduced. The difference between the combustion state and the combustion state in the cylinders of the second cylinder group can be effectively reduced.

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the first opening area and the second opening area are determined by the first scroll portion under an operating state in which the load of the internal combustion engine is maximum. The exhaust flow rate flowing through the second scroll portion is set to be equal to the exhaust flow rate flowing through the second scroll portion.

  According to this aspect, as described above, generally, the amount of residual gas in the cylinders of the first cylinder group that supplies the first exhaust to the first exhaust passage, the first scroll portion, and the first bypass passage, The difference from the residual gas amount in the cylinders of the second cylinder group that supplies the second exhaust gas to the two exhaust passages, the second scroll portion, and the second bypass passage is the load of the internal combustion engine (typically, the intake air amount). Increases as becomes larger. Therefore, according to this aspect, the difference between the residual gas amount in the cylinders of the first cylinder group and the residual gas amount in the cylinders of the second cylinder group is determined in a wide range of the load of the internal combustion engine. The difference between the residual gas amount in the cylinder and the residual gas amount in the cylinders of the second cylinder group can be reduced more effectively. As a result, the combustion state in the cylinders of the first cylinder group and the second cylinder group can be reduced. The difference from the combustion state in the cylinder can be reduced more effectively.

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the first bypass passage is a first valve capable of changing a flow rate of the first exhaust that bypasses the turbine and is guided downstream from the turbine. The second bypass passage has a second valve that can change the flow rate of the second exhaust gas that is bypassed the turbine and guided downstream from the turbine.

  According to this aspect, the flow rates of the first exhaust gas and the second exhaust gas guided to the turbine and the flow rates of the first exhaust gas and the second exhaust gas that bypass the turbine can be changed by the first valve and the second valve. The ratio between the supercharging pressure and the exhaust pressure in the intake system can be set to an appropriate value. Thereby, the compression ratio in the cylinder can be set to an appropriate value, combustion failure in the cylinder such as knocking can be effectively suppressed, and deterioration of fuel consumption can be effectively suppressed. .

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the timing of performing an exhaust stroke of one cylinder included in the first cylinder group and the exhaust stroke of another cylinder included in the first cylinder group. The time interval between the execution times is longer than the time interval between the execution timing of the exhaust stroke of the one cylinder and the execution timing of the exhaust strokes of the other cylinders included in the second cylinder group.

  According to this aspect, the first exhaust exhausted in the exhaust stroke of one cylinder included in the first cylinder group and the other exhaust discharged in the exhaust stroke of the other cylinders included in the first cylinder group. It is possible to more effectively suppress the occurrence of exhaust interference that collides with one exhaust and reduces the flow rate of the exhaust. As a result, an increase in exhaust pressure due to exhaust interference can be suppressed, and the first exhaust can be discharged appropriately and quickly, so that intake air is sucked into a plurality of cylinders appropriately and quickly, and combustion failure in the cylinders is prevented. It is possible to effectively suppress the deterioration of the fuel consumption.

  In another aspect of the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, the timing of exhaust strokes of one cylinder included in the second cylinder group and the exhaust strokes of other cylinders included in the second cylinder group. The time interval between the execution times is longer than the time interval between the execution timing of the exhaust stroke of the one cylinder and the execution timing of the exhaust stroke of the other cylinders included in the first cylinder group.

  According to this aspect, one second exhaust exhausted in the exhaust stroke of one cylinder included in the second cylinder group and another second exhaust exhausted in the exhaust stroke of another cylinder included in the second cylinder group. It is possible to more effectively suppress the occurrence of exhaust interference that causes the two exhausts to collide with each other and reduce the flow rate of the exhaust. As a result, an increase in exhaust pressure due to exhaust interference can be suppressed and the second exhaust can be discharged appropriately and quickly, so that intake air is sucked into a plurality of cylinders appropriately and quickly, and combustion failure in the cylinders is prevented. It is possible to effectively suppress the deterioration of the fuel consumption.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Various preferred embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
(Basic configuration)
First, with reference to FIG. 1, the structure of the engine system 10 which concerns on 1st Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10 according to the present embodiment.

  In FIG. 1, an engine system 10 is mounted on a vehicle (not shown) and includes an ECU (Electronic Control Unit) 1, an engine 200, and an EGR device 300.

  The engine 200 is an in-line four-cylinder gasoline engine that is an example of an “internal combustion engine” according to the present invention that uses gasoline as fuel. The outline of the engine 200 will be described. The engine 200 has a configuration in which four cylinders # 1 to # 4 are arranged in parallel in a cylinder block 201. The thermal energy generated when the air-fuel mixture containing fuel is ignited by ignition in each cylinder causes a reciprocating motion of a piston (not shown), and further connected to the piston via a connecting rod (both (Not shown). Below, the principal part structure of the engine 200 is demonstrated with a part of the operation | movement.

  The engine 200 according to this embodiment is an in-line four-cylinder gasoline engine in which four cylinders # 1 to # 4 are arranged in parallel in a direction perpendicular to the paper surface in FIG. Since these configurations are equal to each other, only one cylinder # 1 will be described here.

  During combustion of the air-fuel mixture in the cylinder # 1, the air sucked from the outside is led to the intake manifold 203 that is commonly installed for each cylinder, and then the intake port (not shown) provided independently for each cylinder. When the intake valve (not shown) configured to allow communication between the intake port and the inside of the cylinder is opened, the air is drawn into the cylinder # 1. In cylinder # 1, gasoline as fuel is injected from an in-cylinder direct injection type injector (not shown), and the injected fuel is sucked into each cylinder (hereinafter referred to as “ Abbreviated as “intake”) to form the above-described mixture.

  In engine 200, fuel is stored in a fuel tank (not shown). The fuel stored in the fuel tank is pumped out of the fuel tank by the action of a feed pump (not shown) and is pumped to a high pressure pump (not shown) through a low pressure pipe (not shown). The high-pressure pump is configured to be able to supply fuel to a common rail (not shown). Note that the high-pressure pump and the common rail can take various known modes, and details thereof are omitted here.

  Here, to supplement the configuration of the injector, the injector includes an electromagnetic valve that operates based on a command supplied from an ECU (Electronic Control Unit) 1 and a nozzle that injects fuel when the electromagnetic valve is energized (both of which are inactive). As shown). The ECU is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is configured to be able to control the entire operation of the engine 200. The ECU is configured to be able to execute various controls according to a control program stored in the ROM. The solenoid valve is configured to be able to control a communication state between a pressure chamber to which a high-pressure fuel of a common rail is applied and a low-pressure side low-pressure passage connected to the pressure chamber. The pressurization chamber and the low-pressure passage are communicated with each other, and the pressurization chamber and the low-pressure passage are shut off from each other when energization is stopped. On the other hand, the nozzle has a built-in needle for opening and closing the nozzle hole, and the fuel pressure in the pressure chamber urges the needle in the valve closing direction (direction in which the nozzle hole is closed). Therefore, when the solenoid chamber is energized, the pressurization chamber communicates with the low-pressure passage, and when the fuel pressure in the pressure chamber decreases, the needle rises in the nozzle and opens (opens the nozzle hole). The supplied high-pressure fuel can be injected from the injection hole. In addition, when the energization of the solenoid valve is stopped, the pressurization chamber and the low pressure passage are cut off from each other and the fuel pressure in the pressure chamber rises, and the needle is lowered in the nozzle to close the valve, thereby terminating the injection. It has become. The fuel is configured such that fuel corresponding to the target injection amount is injected into each cylinder # 1 to # 4 via an injector.

  In particular, focusing on the exhaust manifold 209, the cylinder # 1 and the cylinder # 4 of the engine 200 communicate with each other at the junction 209a. In addition, paying attention to the exhaust manifold 210, the cylinder # 2 and the cylinder # 3 of the engine 200 communicate with each other at the junction 210a. Note that the firing order of each cylinder is the order of cylinder # 1, cylinder # 3, cylinder # 4, and cylinder # 2.

  Generally, the distance of the flow path on the exhaust manifold 209 from the exhaust valve of the cylinder # 1 to the merging portion 209a, the distance of the flow path on the exhaust manifold 209 from the exhaust valve of the cylinder # 4 to the merging portion 209a, The distance of the flow path on the exhaust manifold 210 from the exhaust valve of the cylinder # 2 to the merge part 210a and the distance of the flow path on the exhaust manifold 210 from the exhaust valve of the cylinder # 3 to the merge part 210a are mounted on the vehicle. The length of the flow path is different depending on the spatial restrictions and economic cost when doing so. In addition, the shape of the exhaust manifold 209 and the shape of the exhaust manifold 210 in FIG. 1 are examples, and various forms can be taken.

  The air-fuel mixture sucked into the cylinders # 1 and # 4 is ignited and burned by ignition in the compression stroke, and is burnt gas or partially unburned air-fuel mixture in conjunction with opening and closing of the intake valve. The exhaust valve (not shown) that opens and closes is guided to the exhaust manifold 209 via an exhaust port (not shown) when the valve is opened. In substantially the same manner, the air-fuel mixture sucked into the cylinders # 2 and # 3 is ignited and burned by ignition in the compression stroke, and becomes a burned gas or a partially unburned air-fuel mixture. When the exhaust valve that opens and closes in conjunction with opening and closing is opened, the exhaust manifold 210 is guided through the exhaust port. The exhaust manifold 209 according to the present embodiment constitutes one specific example of the “first exhaust passage” according to the present invention. Further, the exhaust manifold 210 according to the present embodiment constitutes one specific example of the “second exhaust passage” according to the present invention.

  The exhaust manifold 209 communicates with the exhaust pipe 211 via a bypass passage 131 and a valve 141, which will be described later, and a part of the exhaust discharged from the cylinders # 1 and # 4 is guided to the exhaust pipe 211. It is configured to be written. In general, the exhaust manifold 210 communicates with the exhaust pipe 211 via a bypass passage 132 and a valve 142, which will be described later, and part of the exhaust discharged from the cylinders # 2 and # 3 The exhaust pipe 211 is guided.

  The exhaust pipe 211 is provided with a catalyst (so-called Start Catalyst) 217, a bypass passage that bypasses the catalyst 217, and a valve 218 that can change the flow rate of the bypass passage. The catalyst 217 is provided on the downstream side of a turbine 170 described later, and quickly cleans harmful gases in the exhaust when it is cold immediately after the engine is started. Further, the exhaust pipe 211 may be provided with a muffler on the downstream side of the turbine 170 described later. Furthermore, a device for reducing pressure loss when exhaust flows through the muffler may be provided.

  On the other hand, a turbine 170 is installed in the exhaust pipe 211 so as to be accommodated in the turbine housing 100. The turbine 170 is configured to be rotatable about a predetermined rotation axis by the pressure of the exhaust led to the exhaust pipe 211. The rotating shaft of the turbine 170 is shared with the compressor 215 installed in the intake pipe 214 so as to be accommodated in the compressor housing 216. When the turbine 170 is rotated by exhaust pressure, the compressor 215 is also centered on the rotating shaft. It becomes the composition which rotates as. A specific example of the “supercharger” according to the present invention is configured by the turbine rising 100, the components in the turbine rising 100, and the components in the compressor housing 216 and the compressor housing 216.

  The compressor 215 is configured to be able to pump the intake air guided to the intake pipe 214 from the outside through an air cleaner (not shown) to the above-described intake manifold 203 by the pressure accompanying the rotation. So-called supercharging is realized by the pumping effect of the intake air. The intake manifold 203 may be provided with a surge tank. In other words, the turbine 170 and the compressor 215 constitute a kind of turbocharger. An intercooler 217 is installed between the compressor 215 and the intake manifold 203, and is configured to cool the supercharged intake air. The supercharging efficiency is improved by the cooling effect of the intercooler 217.

  The intake pipe 214 is provided with a throttle valve 218 capable of adjusting the amount of intake air. The throttle valve 218 is a rotary valve that is electrically connected to the ECU described above and is configured to be rotatable by a driving force supplied from a throttle valve motor 219 that is controlled by the ECU above. The rotation position is continuously controlled from the fully closed position where the upstream portion and the downstream portion of the intake pipe 214 at the boundary are substantially blocked to the fully opened position where the intake pipe 214 communicates almost entirely. The engine 200 is controlled through air-fuel ratio control (intake air amount control).

  A water jacket for circulating and supplying cooling water such as LLC is provided at the outer peripheral portion of the cylinders # 1 to # 4 in the cylinder block 201 that accommodates the cylinders # 1 to # 4. The whole engine 200 including # 4 is configured to be cooled.

  In this embodiment, the engine 200 is configured as a gasoline engine. However, the internal combustion engine according to the present invention can be similarly applied to an engine using diesel or alcohol as fuel. Furthermore, the cylinder arrangement may be varied.

  Next, the EGR device 300 will be described. The EGR device 300 includes an EGR passage 310, an EGR cooler 320, and an EGR valve 360, and is configured to be able to circulate a part of the exhaust gas to the intake pipe 214.

  One end of the EGR passage 310 is communicated with the exhaust manifold 209 via an EGR passage port 151, a bypass passage 131, and a scroll portion 121, which will be described later, and the inside thereof is a hollow and metal made communicating with the exhaust manifold 209. It is piping and is an example of the “EGR passage” according to the present invention. The other end of the EGR passage 310 is connected to the intake pipe 214 in the vicinity of the connection portion with the intake manifold 203, and communicates with the intake pipe 214 therein. The intake manifold 203 or the intake pipe 214 described above is an example of the “intake system” according to the present invention.

  The EGR cooler 320 is a cooling system or a cooling device provided in the EGR passage 310. The EGR cooler 320 has a configuration in which the cooling water piping of the engine 200 is stretched around the outer periphery, and the exhaust gas that is guided to the EGR passage 310 and passes through the EGR cooler 320 (that is, the “EGR gas” according to the present embodiment). This is an example, and hereinafter, referred to as “EGR gas”) is cooled by heat exchange with the cooling water and guided to the downstream side (that is, the intake pipe 214 side). Specifically, the EGR cooler 320 is connected to an inlet pipe and an outlet pipe, each of which communicates with the above-described water jacket. Cooling water flows from the inlet pipe 321 into the cooling water pipe, and passes through the outlet pipe. Are discharged outside the cooling water pipe. The discharged cooling water is returned to the cooling water circulation system of the engine 200, and is supplied again from the inlet pipe through a predetermined path.

  The EGR valve 360 is an electromagnetic on-off valve that is installed in the EGR passage 310 and configured to variably control the amount of EGR gas by opening degree control. The EGR valve 360 is electrically connected to the ECU 1 described above, and its opening degree is controlled by the ECU.

  Note that the EGR gas amount itself including whether or not the EGR gas is introduced is variably controlled by the opening degree control of the EGR valve 360, and the opening degree of the EGR valve 360 is controlled by the ECU described above. For example, based on experimental, empirical, theoretical, or simulation in advance, there is a practical problem with various performance requirements different from emissions, including power performance that affects drivability in steady state. It is adapted to suppress the generation of NOx and PM as efficiently as possible within a range that does not decrease so much as it occurs.

(Detailed configuration)
Next, the detailed configuration inside the turbine housing 100 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view conceptually showing the structure of the turbine housing according to the present embodiment.

  As shown in FIG. 2, exhaust passage ports 111 and 112, scroll chambers 121 and 122, bypass passages 131 and 132, valves (so-called waste gate valves) 141 and 142, EGR passage ports are provided inside the turbine housing 100. 151 and a turbine 170.

  Exhaust gas is led to the exhaust passage port 111 from an exhaust manifold 209 communicating with the cylinders # 1 and # 4. Exhaust gas is guided to the exhaust passage port 112 from an exhaust manifold 210 communicating with the cylinders # 2 and # 3.

  The scroll chamber 121 continuously supplies the exhaust led from the exhaust passage port 111 to the turbine 170. At the same time or in succession, the scroll chamber 122 continuously supplies the exhaust guided from the exhaust passage port 112 to the turbine 170. The scroll chamber 121 according to the present embodiment constitutes a specific example of the “first scroll portion” according to the present invention. Further, the scroll chamber 122 according to the present embodiment constitutes one specific example of the “second scroll part” according to the present invention. Specifically, the scroll chambers 121 and 122 constitute a so-called twin scroll.

  In particular, the bypass passage 131 can introduce the exhaust led to the scroll chamber 121 into the exhaust pipe 211 downstream of the turbine 170 while bypassing the turbine 170. The flow rate of the exhaust gas flowing through the bypass passage 131 can be changed by the opening degree of the valve 141. In substantially the same manner, the bypass passage 132 can introduce the exhaust gas guided to the scroll chamber 122 into the exhaust pipe 211 downstream of the turbine 170 while bypassing the turbine 170. The flow rate of the exhaust gas flowing through the bypass passage 132 can be changed by the opening degree of the valve 142. In addition, the opening / closing operation | movement of the valve 141 and the valve 142 may be performed simultaneously via a common member, or may be performed separately.

Thereby, the flow rate of the exhaust gas from the cylinders # 1 to # 4 guided to the turbine 170 and the flow rate of the exhaust gas from the cylinders # 1 to # 4 bypassing the turbine can be changed by the valve 141 and the valve 142. The ratio between the supercharging pressure and the exhaust pressure in the intake system can be set to an appropriate value. Thereby, the compression ratio in the cylinder can be set to an appropriate value, combustion failure in the cylinder such as knocking can be effectively suppressed, and deterioration of fuel consumption can be effectively suppressed. In particular, the bypass passage 131 communicates via an EGR passage 310 that recirculates a part of the exhaust gas guided to the scroll chamber 121 to the intake system as EGR gas, and an EGR passage port 151 located upstream of the turbine 170. is doing. Here, the “EGR passage” according to the present embodiment is a passage that branches from an exhaust system as a concept that may appropriately include, for example, an exhaust port, an exhaust manifold, an exhaust pipe, and the like, and recirculates part of the exhaust to the intake system. Means. Typically, this EGR passage can control the flow rate of EGR gas directly or indirectly to an intake system as a concept that can appropriately include, for example, an intake port, an intake manifold and an intake pipe, or an EGR valve. The exhaust system led to the EGR passage and exhausted to the exhaust system contains a relatively large amount of inactive CO 2. The EGR gas may be recirculated to the intake system. Qualitatively speaking, the EGR gas is somewhat mixed with the intake air supplied to the intake system, and thus includes, for example, NOx or the like (PM (Particulate Matter: particulate matter) depending on the form of the internal combustion engine). ), The generation of various target substances is somewhat suppressed. As a result, compared with the case where the bypass passage 131 communicates with the EGR passage 310 on the downstream side of the turbine 170, the EGR gas is recirculated to the intake system in a state higher than the supercharging pressure of the intake system. Therefore, EGR gas can be supplied at a more appropriate pressure. The detour passage 131 according to the present embodiment constitutes a specific example of the “first detour passage” according to the present invention. The detour passage 132 according to the present embodiment constitutes a specific example of the “second detour passage” according to the present invention.

  Specifically, the cross-sectional area of the bypass passage 131 is preferably smaller than the cross-sectional area of the bypass passage 132. In addition to or instead of making the flow passage cross-sectional area of the bypass passage 131 smaller than the flow passage cross-sectional area of the bypass passage 132, the opening area of the valve 141 of the bypass passage 131 is set to the opening of the valve 142 of the bypass passage 132. You may make it smaller than an area. As a result, the exhaust pressure of the bypass passage 131 can be increased according to the cross-sectional area of the bypass passage 131 in the bypass passage 131 in which the exhaust pressure tends to decrease as compared with the bypass passage 132 by communicating with the EGR passage 310. . Thereby, the difference between the exhaust pressure of the bypass passage 131 and the exhaust pressure of the bypass passage 132 can be effectively reduced. This effectively reduces the difference between the pressure inside the cylinders # 1 and # 4 that exhaust the exhaust gas to the bypass passage 131 and the pressure inside the cylinders # 2 and # 3 that exhaust the exhaust gas to the bypass passage 132. be able to. As a result, the difference between the residual gas amount in the cylinders # 1 and # 4 and the residual gas amount in the cylinders # 2 and # 3 can be effectively reduced. The difference between the combustion state and the combustion state in the cylinders # 2 and # 3 can be effectively reduced. If the cross-sectional area of the bypass passage 131 is equal to the cross-sectional area of the bypass passage 132, or if the cross-sectional area of the bypass passage 131 is larger than the cross-sectional area of the bypass passage 132, Since the passage 131 communicates with the EGR passage, the pressure of the exhaust gas decreases, and the exhaust pressure that affects the pressure in the cylinders # 1 and # 4 and the pressure in the cylinders # 2 and # 3 are affected. There is a difference between the exhaust pressure to be applied and there is a possibility that problems such as abnormal vibration of the engine may occur.

  Generally, the amount of residual gas in cylinders # 1 and # 4 that exhausts exhaust to exhaust manifold 209, scroll chamber 121, and bypass passage 131, and the cylinder that exhausts exhaust to exhaust manifold 210, scroll chamber 122, and bypass passage 132 The difference from the amount of residual gas in # 2 and # 3 increases as the load (typically intake air amount) of the internal combustion engine increases. Therefore, in addition to or instead of the flow path cross-sectional area of the bypass path 131 being smaller than the flow path cross-sectional area of the bypass path 132, the flow path cross-sectional area of the bypass path 131 and the flow path cross-sectional area of the bypass path 132 are Is preferably set so that the exhaust flow rate flowing through the scroll chamber 121 and the exhaust flow rate flowing through the scroll chamber 122 become equal under an operating condition in which the load of the internal combustion engine is maximum. More specifically, the exhaust flow rate flowing through the scroll chamber 121 and the exhaust flow rate flowing through the scroll chamber 122 are equal under the engine operating state where the maximum amount of air is obtained with the EGR gas recirculated or recirculated. It is preferable to set so as to be. As a result, the difference between the residual gas amount in the cylinders # 1 and # 4 and the residual gas amount in the cylinders # 2 and # 3 is determined over a wide range of the load of the internal combustion engine, and the residual gas amount in the cylinders # 1 and # 4. And the residual gas amount in the cylinders # 2 and # 3 can be reduced more effectively. As a result, the combustion state in the cylinders # 1 and # 4 and the combustion in the cylinders # 2 and # 3 can be reduced. The difference from the state can be reduced more effectively. Thereby, the residual gas amounts in the cylinders # 1 to # 4 can be effectively equalized, and consequently the combustion states in the cylinders # 1 to # 4 can be effectively equalized.

  As a result, according to the present embodiment, in the twin scroll type supercharger, (i) appropriate adjustment of the ratio between the supercharging pressure and the exhaust pressure in the intake system, and (ii) the supply pressure of EGR gas Therefore, it is possible to achieve high supercharging in a low speed operation region.

(Examination of actions and effects according to this embodiment)
Next, in addition to FIGS. 3 and 4, the operation and effects according to the present embodiment will be examined with reference to FIG. 2 described above as appropriate. FIG. 3 is a schematic diagram conceptually showing the exhaust manifold according to the present embodiment focusing on the flow path (FIG. 3A) and the exhaust manifold according to the comparative example. It is the schematic diagram (FIG.3 (b)) shown conceptually paying attention to. FIG. 4 is a timing chart conceptually showing the timing of each stroke in the cylinders # 1 to # 4 according to the present embodiment. For convenience of explanation, each stroke in FIG. 4 corresponds to a crank angle of 180 degrees, and the time of each stroke can be uniquely defined by the crank angle and the engine rotation speed.

(Reducing the thermal load of the EGR gas cooling system)
First, the principle of reducing the thermal load of the cooling system that cools the EGR gas will be described. As shown in FIG. 3A and FIG. 2 described above, the length of the flow path between the cylinder # 1 and the merging portion 209a where the exhaust discharged from the cylinders # 1 and # 4 merges is the cylinder In addition to being larger than the length of the flow path between # 2 and the merge section 210a where the exhaust discharged from the cylinders # 2 and # 3 merges, the flow path between the cylinder # 3 and the merge section 210a It is preferable that the length is larger. Further, the length of the flow path between the cylinder # 4 and the merging portion 209a is larger than the length of the flow path between the cylinder # 2 and the merging portion 210a. It is preferable that it is larger than the length of the flow path between the part 210a. Thereby, the time until the exhaust discharged from the cylinders # 1 and # 4 joins can be made longer than the time until the exhaust discharged from the cylinders # 2 and # 3 joins. Therefore, the exhaust discharged from the cylinders # 1 and # 4 is burned in the exhaust system other than the cylinder combustion chamber (so-called afterburning) in a larger amount than the exhaust discharged from the cylinders # 2 and # 3. Therefore, it is possible to effectively suppress an increase in oxygen contained in the exhaust gas by joining the exhaust gases discharged from the cylinders # 1 and # 4. Accordingly, the temperature of the exhaust gas guided to the EGR passage 310 via the exhaust manifold 209, the scroll chamber 121, the bypass passage 131, and the EGR passage port 151 is changed to the exhaust manifold 210, the scroll chamber 122, and the bypass passage 132. It can be made lower than the temperature. As a result, the heat load applied to the cooling system provided in the EGR passage 310 can be effectively reduced. As a result of the above, it is possible to reduce the temperature of the intake air by the EGR gas cooled more effectively, and this reduced intake air increases the amount of intake air that is taken into the cylinder. Can be improved.

  Generally, the exhaust gas (or exhaust gas) burned in each cylinder is burned by the residual oxygen and unburned substances in the exhaust gas even after being discharged from the exhaust valve. That is, if the length of the flow path until the exhaust discharged from the cylinders # 1 and # 4 merges is smaller than the length of the flow path until the exhaust discharged from the cylinders # 2 and # 3 merges Technology that exhausts merge and oxygen and unburned substances are added in a state where there are a lot of oxygen and unburned substances, so that the combustion reaction is activated and the temperature of the exhaust gas is likely to rise. Problems arise.

(Suppression of exhaust interference (part 1))
Next, the principle (part 1) for suppressing the occurrence of exhaust interference will be described. As shown in FIG. 2 and FIG. 3A, the above-described one exhaust system in which exhaust gas is supplied from the cylinders # 1 and # 4 to the exhaust manifold 209 and exhaust gas from the cylinders # 2 and # 3 to the exhaust manifold 210 are exhausted. Is physically separated from the other exhaust system supplied with the exhaust gas discharged from the cylinders # 1 and # 4 via the merging portion 209a and the merging portion 210a. The exhaust discharged from the cylinders # 2 and # 3 can be physically separated and guided to the supercharger. This effectively suppresses the occurrence of exhaust interference that causes the exhaust exhausted from cylinders # 1 and # 4 and the exhaust exhausted from cylinders # 2 and # 3 to collide with each other and reduce the exhaust flow velocity. it can. As a result, an increase in exhaust pressure caused by exhaust interference can be suppressed, and exhaust exhausted from cylinders # 1 and # 4 and exhaust exhausted from cylinders # 2 and # 3 can be appropriately and quickly exhausted. The intake air can be sucked into a plurality of cylinders appropriately and quickly, and combustion failure in the cylinders can be effectively suppressed, and deterioration of fuel consumption can be effectively suppressed. As shown in FIG. 3B, when the exhaust from the cylinders # 1 to # 4 merges into one merging portion, the exhaust discharged from the cylinders # 1 to # 4 collides with each other and The degree of occurrence of exhaust interference that reduces the flow velocity increases, exhaust pressure increases, and technical problems arise that exhaust from a plurality of cylinders cannot be discharged smoothly.

(Suppression of exhaust interference (part 2))
Next, the principle (part 2) for suppressing the occurrence of exhaust interference will be described. As shown in FIG. 4, the exhaust time of cylinder # 1 (see time T4 in FIG. 4) and the exhaust time of cylinder # 4 (see time T2 in FIG. 4). The time interval between them is based on the time interval between the timing of exhaust stroke of cylinder # 1 and the timing of exhaust stroke of cylinder # 2 or # 3 (see time T3, T5 or T1 in FIG. 4). It is preferable to set the length to be long. Typically, it is preferable to shift the crank angle between the execution timing of the exhaust stroke of cylinder # 1 and the execution timing of the exhaust stroke of cylinder # 4 by 360 degrees. As a result, the exhaust discharged in the exhaust stroke of cylinder # 1 (see the exhaust at time T4 in FIGS. 3 and 4) and the exhaust discharged in the exhaust stroke of cylinder # 4 (in FIGS. 3 and 4). Occurrence of exhaust interference that collides with each other and reduces the flow rate of exhaust gas can be more effectively suppressed. As a result, an increase in exhaust pressure due to exhaust interference can be suppressed, and exhaust exhausted from cylinders # 1 and # 4 can be exhausted appropriately and quickly. In addition, it is possible to effectively suppress the combustion failure in the cylinder, and thus it is possible to effectively suppress the deterioration of the fuel consumption. For the same reason, the timing of exhaust stroke of cylinder # 2 (see time T3 in FIG. 4) and the timing of exhaust stroke of cylinder # 3 (see time T5 or T1 in FIG. 4). Is a time interval between the timing of exhausting the cylinder # 2 and the timing of exhausting the cylinder # 1 or # 4 (see time T4 or T2 in FIG. 4). It is preferable to set the length to be long.

  As a result of the above, according to the present embodiment, in the twin scroll type supercharger, (i) appropriate adjustment of the ratio of the supercharging pressure and exhaust pressure in the intake system, and (ii) the EGR gas In addition to the appropriate adjustment of the supply pressure, (iii) effective reduction of the heat load of the EGR gas cooling system, and (iv) effective suppression of the occurrence of exhaust interference, High supercharging can be realized.

  In the above-described embodiment, a four-cylinder engine has been described. However, the present invention can be applied to a multi-cylinder engine such as a six-cylinder engine.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. A reflux apparatus is also included in the technical scope of the present invention.

1 is a schematic configuration diagram conceptually showing a configuration of an engine system 10 according to the present embodiment. It is a schematic sectional drawing which expresses the composition of the turbine housing concerning this embodiment notionally. The schematic diagram (FIG. 3A) conceptually showing the exhaust manifold according to the present embodiment focusing on the flow path and the exhaust manifold according to the comparative example conceptually focusing on the length of the flow path. It is the schematic diagram shown (FIG.3 (b)). It is a timing chart which showed notionally the time of each stroke in cylinders # 1 to # 4 concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... ECU, 10 ... Engine system, 100 ... Turbine housing, 111 and 112 ... Exhaust passage port, 121 and 122 ... Scroll chamber, 131 and 132 ... Detour passage, 141 and 142 ... Valve (so-called waste gate valve), 151 ... EGR passage port, 170 ... turbine, 200 ... engine, 300 ... EGR device, 310 ... EGR passage, 320 ... EGR cooler, 360 ... EGR valve.

Claims (9)

A turbocharger having a turbine in an exhaust system of an internal combustion engine having a plurality of cylinders and supercharging in an intake system of the internal combustion engine;
A first exhaust passage that includes a first merging portion where the first exhaust from the first cylinder group of the plurality of cylinders merges, and that guides the first exhaust to the supercharger via the first merging portion. When,
A second exhaust passage that includes a second merging portion where the second exhaust from the second cylinder group of the plurality of cylinders merges, and guides the second exhaust to the supercharger via the second merging portion. When,
A first scroll portion for continuously guiding the first exhaust from the first exhaust passage to the turbine;
A second scroll portion for continuously guiding the second exhaust from the second exhaust passage to the turbine;
In addition to being able to introduce the first exhaust gas guided to the first scroll part to the downstream side of the turbine by bypassing the turbine, the first exhaust gas guided to the first scroll part An EGR passage for recirculating a part of the EGR gas to the intake system and a first bypass passage communicating with the upstream side of the turbine;
An exhaust gas recirculation device for an internal combustion engine, comprising: a second bypass passage capable of bypassing the second exhaust gas guided to the second scroll portion and introducing the second exhaust gas downstream from the turbine.   The length of the flow path between one cylinder included in the first cylinder group and the first merging portion is the flow between another cylinder included in the second cylinder group and the second merging portion. 2. The exhaust gas recirculation device for an internal combustion engine according to claim 1, wherein the exhaust gas recirculation device is longer than a length of the path.   3. The exhaust gas recirculation apparatus for an internal combustion engine according to claim 1, wherein a flow passage cross-sectional area of the first bypass passage is smaller than a flow passage cross-sectional area of the second bypass passage.   The flow passage cross-sectional area of the first bypass passage and the flow passage cross-sectional area of the second bypass passage are the exhaust flow rate flowing through the first scroll portion under the operating condition where the load of the internal combustion engine is maximum, and The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 3, wherein the exhaust gas flow rate flowing through the second scroll portion is set to be equal. The first bypass passage and the second bypass passage can be blocked by a valve body,
The first opening area of the valve body in the first bypass path is smaller than the second opening area of the valve body in the second bypass path. An exhaust gas recirculation device for an internal combustion engine.   The first opening area and the second opening area are defined as an exhaust flow rate flowing through the first scroll portion and an exhaust flow rate flowing through the second scroll portion under an operating state in which the load of the internal combustion engine is maximum. The exhaust gas recirculation apparatus for an internal combustion engine according to any one of claims 1 to 5, wherein the exhaust gas recirculation apparatus is set to be equal. The first bypass passage has a first valve capable of changing the flow rate of the first exhaust gas that bypasses the turbine and is guided downstream from the turbine;
The said 2nd bypass path has a 2nd valve which can change the flow volume of the said 2nd exhaust gas which bypasses the said turbine and is guide | induced to the downstream from the said turbine. The exhaust gas recirculation device for an internal combustion engine according to one item.   The time interval between the execution timing of the exhaust stroke of one cylinder included in the first cylinder group and the execution timing of the exhaust stroke of other cylinders included in the first cylinder group is the exhaust time of the one cylinder. The time interval between the execution timing of the stroke and the execution timing of the exhaust stroke of another cylinder included in the second cylinder group is longer than any one of claims 1 to 7. An exhaust gas recirculation device for an internal combustion engine.   The time interval between the execution timing of the exhaust stroke of one cylinder included in the second cylinder group and the execution timing of the exhaust stroke of other cylinders included in the second cylinder group is the exhaust time of the one cylinder. 9. The method according to claim 1, wherein a time interval between an execution time of a stroke and an execution time of an exhaust stroke of another cylinder included in the first cylinder group is longer. An exhaust gas recirculation device for an internal combustion engine.

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