JP4742970B2 - Exhaust gas recirculation device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

  A turbocharger having a turbine in the exhaust passage and a compressor in the intake passage is provided. The exhaust passage downstream of the turbine and the intake passage upstream of the compressor are connected, and a part of the exhaust from the internal combustion engine is used as the intake passage. An exhaust gas recirculation device for an internal combustion engine having a low pressure EGR passage for recirculation is known. Since the exhaust gas that has passed through the turbine and the catalyst is introduced into the low pressure EGR passage, the temperature of the EGR gas flowing through the low pressure EGR passage is low. Therefore, when the exhaust gas that has entered the low-pressure EGR passage is cooled by the EGR cooler, water condenses in the EGR cooler, and water accumulates in the EGR cooler or the like. Here, since sulfur components and the like are included in the exhaust gas, these components are also included in the condensed water. Since these components corrode the EGR cooler, the performance of the EGR cooler is degraded.

  Further, if particulate matter (hereinafter referred to as PM) in the EGR gas adheres to the low-pressure EGR gas passage, the EGR cooler, the EGR valve, or the like, there is a possibility that the flow rate of the EGR gas or the cooling efficiency of the EGR cooler may decrease. is there.

  Hereinafter, substances adhering to the low pressure EGR gas passage such as condensed water and PM are collectively referred to as deposit.

  Further, if the deposit becomes a large lump and then the lump enters the intake passage from the low pressure EGR passage, the compressor may be deformed or the intercooler may be clogged.

Here, a technique is known in which a large amount of EGR gas is caused to flow through the EGR passage by opening the EGR valve during deceleration or idling of the vehicle, thereby scavenging the EGR passage (see, for example, Patent Document 1).
JP 2004-116402 A Japanese Patent Laid-Open No. 11-093781 JP 2003-193896 A JP 2004-150319 A

  However, since the pressure difference between the exhaust passage side and the intake passage side is small in the low pressure EGR passage, the flow rate of the EGR gas does not increase so much just by opening the EGR valve. For this reason, the effect of scavenging in the EGR passage is small. Therefore, deposits may not be removed in the low pressure EGR passage.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of more reliably removing deposits in an EGR passage in an exhaust gas recirculation apparatus for an internal combustion engine.

In order to achieve the above object, an exhaust gas recirculation apparatus for an internal combustion engine according to the present invention employs the following means. That is, the exhaust gas recirculation device for an internal combustion engine according to the present invention is:
A turbocharger having a turbine in the exhaust passage and a compressor in the intake passage;
A low-pressure EGR passage that connects an exhaust passage downstream of the turbine and an intake passage upstream of the compressor and recirculates part of the exhaust from the internal combustion engine to the intake passage;
EGR gas amount adjusting means for adjusting the amount of EGR gas flowing in the low pressure EGR passage according to the state of the internal combustion engine or the vehicle;
During deceleration of the vehicle, fuel cut of the internal combustion engine, or idling operation of the internal combustion engine, the flow rate of the EGR gas in the low pressure EGR passage is set higher than when the amount of EGR gas is adjusted by the EGR gas amount adjusting means. A flow rate increasing means for increasing,
It is characterized by providing.

  The EGR gas amount adjusting means adjusts the amount of EGR gas according to, for example, the rotational speed and load of the internal combustion engine. Usually, the amount of EGR gas is adjusted by the EGR gas amount adjusting means. The normal here is a time other than when the flow rate of the EGR gas is increased by the flow rate increasing means.

  The reason why the flow rate increasing means increases the flow rate of the EGR gas when the vehicle is decelerated, when the fuel cut of the internal combustion engine, or when the internal combustion engine is idling is because the influence on drivability or fuel consumption is small in such a state. is there. If the influence on drivability or fuel consumption is small, the flow rate of the EGR gas may be increased in other states. In addition, when priority is given to deposit removal over drivability or fuel consumption, the flow rate of EGR gas may be increased during deceleration of the vehicle, fuel cut of the internal combustion engine, or idle operation of the internal combustion engine.

  Since the EGR gas having a low temperature after passing through the turbine or the like flows through the low-pressure EGR passage, the condensed water generated in the EGR cooler is difficult to evaporate. Also, the flow rate of EGR gas is slow. On the other hand, the flow rate increasing means increases the flow rate of EGR gas. Thereby, since the deposit in the low pressure EGR passage can be scattered, the scattered deposit can be discharged into the intake passage. Deposits discharged into the intake passage are sucked into the internal combustion engine. Further, by increasing the flow rate of the EGR gas in the low-pressure EGR passage while the deposit is small, it is possible to suppress deterioration of the function of the compressor or the like due to the deposit.

In the present invention, a low pressure EGR valve that adjusts the amount of EGR gas flowing through the low pressure EGR passage;
An exhaust throttle valve that adjusts the amount of exhaust gas flowing through the exhaust passage downstream from the location where the low-pressure EGR passage is connected;
An exhaust throttle valve opening adjusting means for adjusting the opening of the exhaust throttle valve according to the state of the internal combustion engine or the vehicle;
Further comprising
The flow rate increasing means increases the flow rate of EGR gas so that the low pressure EGR valve is not fully closed and the opening of the exhaust throttle valve is closed compared to when the exhaust throttle valve opening adjusting means is adjusted. Can be made.

  The low-pressure EGR valve can be fully opened, fully closed, or any opening from fully open to fully closed, and the flow rate of EGR gas is adjusted by adjusting the opening. If the low-pressure EGR valve is set to an opening degree that is not fully closed, EGR gas can flow through the low-pressure EGR passage. By setting the exhaust throttle valve to the closed side or fully closed, the pressure in the exhaust passage closer to the internal combustion engine than the exhaust throttle valve can be increased. Thereby, since the pressure difference between the exhaust passage side and the intake passage side becomes large, the flow rate of the EGR gas flowing through the low pressure EGR passage can be increased.

In the present invention, a low pressure EGR valve that adjusts the amount of EGR gas flowing through the low pressure EGR passage;
An intake throttle valve that adjusts the amount of intake air that flows through the intake passage upstream from the point where the low-pressure EGR passage is connected;
An intake throttle valve opening adjusting means for adjusting the opening of the intake throttle valve according to the state of the internal combustion engine or the vehicle;
Further comprising
The flow rate increasing means increases the flow rate of EGR gas so that the low pressure EGR valve is not fully closed and the opening of the intake throttle valve is more closed than when the intake throttle valve opening adjusting means is adjusted. Can be made.

  As described above, if the low-pressure EGR valve is set to an opening degree that is not fully closed, EGR gas can flow through the low-pressure EGR passage. By setting the intake throttle valve to the closed side or fully closed, the pressure in the intake passage on the internal combustion engine side than the intake throttle valve can be lowered. Thereby, since the pressure difference between the exhaust passage side and the intake passage side becomes large, the flow rate of the EGR gas flowing through the low pressure EGR passage can be increased.

In the present invention, a high-pressure EGR passage that connects an exhaust passage upstream of the turbine and an intake passage downstream of the compressor and recirculates part of the exhaust from the internal combustion engine to the intake passage;
A high pressure EGR valve for adjusting the amount of EGR gas flowing through the high pressure EGR passage;
High pressure EGR valve opening degree adjusting means for adjusting the opening degree of the high pressure EGR valve according to the state of the internal combustion engine or the vehicle;
Further comprising
The flow rate increasing means may make the opening of the high pressure EGR valve closer to the closing side than when the high pressure EGR valve opening adjusting means is adjusted.

  In the high-pressure EGR passage, the pressure difference between the exhaust passage side and the intake passage side may become large, and thus the exhaust flow velocity may increase. Moreover, the temperature of EGR gas is also high. For these reasons, condensed water is less likely to be generated in the high pressure EGR passage than in the low pressure EGR passage. Further, even if condensed water is generated, it evaporates immediately, so that it is difficult for PM to adhere. Furthermore, even if the deposit adheres and becomes a large lump and is discharged into the intake passage, the lump does not pass through the compressor or the like, so that these functions are hardly deteriorated. Therefore, unlike the low pressure EGR passage, there is almost no need to increase the flow rate of the EGR gas.

  On the other hand, when the EGR gas flows through the high-pressure EGR passage, the amount of exhaust flowing into the exhaust passage downstream of the high-pressure EGR passage decreases. Therefore, the amount of EGR gas flowing through the low pressure EGR passage is also reduced. On the other hand, when increasing the flow rate of the EGR gas in the low pressure EGR passage, the EGR gas is prevented from flowing into the high pressure EGR gas passage. Thereby, since the reduction | decrease of the quantity of EGR gas which flows through a low pressure EGR channel | path can be suppressed, a deposit can be discharged | emitted more to an intake passage.

  In the present invention, the flow rate of the EGR gas may be increased by opening the low-pressure EGR valve more open than when the opening is adjusted in accordance with the state of the internal combustion engine or the vehicle.

  The exhaust gas recirculation device for an internal combustion engine according to the present invention can more reliably remove the deposit in the EGR passage.

  Hereinafter, specific embodiments of an exhaust gas recirculation device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the exhaust gas recirculation apparatus for an internal combustion engine according to this embodiment is applied and its intake / exhaust system. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders 2.

  An intake pipe 3 and an exhaust pipe 4 are connected to the internal combustion engine 1. In the middle of the intake pipe 3, a compressor housing 5a of a turbocharger 5 that operates using exhaust energy as a drive source is provided. An air flow meter 7 is provided in the intake pipe 3 upstream of the compressor housing 5a to output a signal corresponding to the flow rate of the intake air flowing through the intake pipe 3. The air flow meter 7 measures the intake air amount of the internal combustion engine 1.

  The intake pipe 3 downstream of the compressor housing 5a is provided with an intercooler 8 that exchanges heat between the intake air and the atmosphere. An intake throttle valve 9 for adjusting the flow rate of intake air flowing through the intake pipe 3 is provided in the intake pipe 3 downstream of the air flow meter 7 and upstream of the compressor housing 5a. The intake throttle valve 9 is opened and closed by an electric actuator.

  On the other hand, a turbine housing 5 b of the turbocharger 5 is provided in the middle of the exhaust pipe 4. Further, a particulate filter (hereinafter simply referred to as a filter) 10 is provided in the exhaust pipe 4 downstream of the turbine housing 5b. The filter 10 carries a NOx catalyst.

  The exhaust pipe 4 downstream of the filter 10 is provided with an exhaust throttle valve 11 that adjusts the flow rate of the exhaust gas flowing through the exhaust pipe 4. The exhaust throttle valve 11 is opened and closed by an electric actuator.

  The internal combustion engine 1 is provided with a low pressure EGR device 30 that recirculates a part of the exhaust gas flowing through the exhaust pipe 4 to the intake pipe 3 at a low pressure. The low pressure EGR device 30 includes a low pressure EGR passage 31, a low pressure EGR valve 32, and a low pressure EGR cooler 33.

  The low pressure EGR passage 31 connects the exhaust pipe 4 downstream of the filter 10 and upstream of the exhaust throttle valve 11 and the intake pipe 3 upstream of the compressor housing 5a and downstream of the intake throttle valve 9. Yes. Through this low pressure EGR passage 31, the exhaust gas is recirculated at a low pressure. In this embodiment, the exhaust gas recirculated through the low pressure EGR passage 31 is referred to as low pressure EGR gas. The low pressure EGR valve 32 changes the amount of the low pressure EGR gas flowing through the low pressure EGR passage 31 by changing the passage sectional area of the low pressure EGR passage 31. Further, the low pressure EGR cooler 33 exchanges heat between the low pressure EGR gas passing through the low pressure EGR cooler 33 and the cooling water of the internal combustion engine 1 to lower the temperature of the low pressure EGR gas.

  Further, the internal combustion engine 1 is provided with a high pressure EGR device 40 that recirculates a part of the exhaust gas flowing through the exhaust pipe 4 to the intake pipe 3 at a high pressure. The high pressure EGR device 40 includes a high pressure EGR passage 41, a high pressure EGR valve 42, and a high pressure EGR cooler 43.

The high-pressure EGR passage 41 connects the exhaust pipe 4 upstream of the turbine housing 5b and the intake pipe 3 downstream of the compressor housing 5a. Exhaust gas is recirculated at high pressure through the high pressure EGR passage 41. In this embodiment, the exhaust gas recirculated through the high pressure EGR passage 41 is referred to as high pressure EGR gas. The high pressure EGR valve 42 changes the amount of the high pressure EGR gas flowing through the high pressure EGR passage 41 by changing the passage cross-sectional area of the high pressure EGR passage 41. Further, the high-pressure EGR cooler 43 exchanges heat between the high-pressure EGR gas passing through the high-pressure EGR cooler 43 and the cooling water of the internal combustion engine 1 to reduce the temperature of the high-pressure EGR gas.

  The internal combustion engine 1 configured as described above is provided with an ECU 20 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 20 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver. In addition to the above sensor, the ECU 20 outputs an electric signal corresponding to the amount of depression of the accelerator pedal 14 by the driver, and an accelerator opening sensor 15 that can detect the engine load, and a crank position that detects the engine speed. Sensors 16 are connected via electric wiring, and output signals from these various sensors are input to the ECU 20. On the other hand, the intake throttle valve 9, the exhaust throttle valve 11, the low pressure EGR valve 32, and the high pressure EGR valve 42 are connected to the ECU 20 through electrical wiring, and these devices are controlled by the ECU 20.

For example, the ECU 20 normally controls the low pressure EGR valve 32 and the high pressure EGR valve 42 so that the intake air amount of the internal combustion engine 1 becomes a target value. That is, the opening degree of the low pressure EGR valve 32 and the high pressure EGR valve 42 is adjusted so that the intake air amount detected by the air flow meter 7 becomes a target value determined from the engine speed and the engine load. Further, for example, the relationship between the engine speed, the engine load, and the opening degrees of the low pressure EGR valve 32 and the high pressure EGR valve 42 that can suppress the generation of NOx is obtained in advance through experiments or the like, and is normally mapped. The opening degree of the low pressure EGR valve 32 and the high pressure EGR valve 42 may be adjusted based on the map. In this embodiment, the ECU 20 that adjusts the amount of the low-pressure EGR gas in this way corresponds to the EGR gas amount adjusting means in the present invention. In the present embodiment, the ECU 20 that adjusts the opening degree of the high pressure EGR valve 42 in this way corresponds to the high pressure EGR valve opening degree adjusting means in the present invention.

  Similarly, the ECU 20 normally adjusts the opening degree of the intake throttle valve 9 and the exhaust throttle valve 11 based on the operating state (for example, engine speed and engine load) of the internal combustion engine 1 or the state of the vehicle. In this embodiment, the ECU 20 that adjusts the opening of the exhaust throttle valve 11 in this way corresponds to the exhaust throttle valve opening adjusting means in the present invention. In this embodiment, the ECU 20 that adjusts the opening of the intake throttle valve 9 in this way corresponds to the intake throttle valve opening adjusting means in the present invention.

  In this embodiment, the exhaust throttle valve 11 is fully closed, the low pressure EGR valve is fully opened, and the high pressure EGR valve is when the vehicle is decelerated, the fuel cut of the internal combustion engine 1 or the idle operation of the internal combustion engine 1 is performed. 42 is fully closed.

  The reason why the vehicle is decelerated, the fuel cut of the internal combustion engine 1 or the idling operation of the internal combustion engine 1 is because the influence on drivability and fuel consumption is small in such a case. That is, if the exhaust throttle valve 11 is fully closed in a state other than this, the pressure loss in the exhaust pipe 4 increases, so that drivability and fuel consumption may be deteriorated.

Then, when the exhaust throttle valve 11 is fully closed in an operating state having a small influence on drivability and fuel consumption, the pressure in the exhaust pipe 4 upstream of the exhaust throttle valve 11 increases. Then, the pressure difference between the exhaust pipe 4 side of the low pressure EGR passage 31 and the intake pipe 3 side becomes large. Further, since the high pressure EGR valve 42 is fully closed, the exhaust in the exhaust pipe 4 can be prevented from flowing into the high pressure EGR passage 41. Thereby, the pressure in the exhaust pipe 4 can be further increased. Thus, the flow rate of the low pressure EGR gas in the low pressure EGR passage 31 is increased. Therefore, deposits adhering to the low pressure EGR passage 31, the low pressure EGR valve 32, and the low pressure EGR cooler 33 can be scattered and further discharged onto the intake pipe 3 on the exhaust flow.

  The exhaust throttle valve 11 may be closed instead of being fully closed. The closed side is a closed side with respect to the normal operation state, and when the deposit in the low pressure EGR passage 31 does not need to be discharged and when the vehicle is decelerated, when the fuel cut of the internal combustion engine 1 or when the internal combustion engine 1 is idle It shows that it is closer to the opening side than the opening of the exhaust throttle valve 11 adjusted during operation. Similarly, the low pressure EGR valve 32 may be on the open side, and the high pressure EGR valve 42 may be on the close side. Further, the opening of the low pressure EGR valve 32, the high pressure EGR valve 42, and the exhaust throttle valve 11 immediately before increasing the flow rate of the low pressure EGR gas may be set to the closed side or the open side. This is also because the pressure difference between the exhaust pipe 4 side and the intake pipe 3 side of the low pressure EGR passage 31 can be increased.

  Next, the flow of the flow rate increase control of the low pressure EGR gas according to the present embodiment will be described. FIG. 2 is a flowchart showing a flow of flow rate increase control of the low pressure EGR gas according to the present embodiment. This routine is repeatedly executed every predetermined time.

  In step S101, it is determined whether a condition for increasing the flow rate of the low-pressure EGR gas is satisfied.

  In this step, it is determined whether the vehicle is decelerating, the fuel cut of the internal combustion engine 1 or the idling operation of the internal combustion engine 1. That is, it is determined whether the influence on drivability and fuel consumption is small.

  If an affirmative determination is made in step S101, the process proceeds to step S102, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S102, it is determined whether or not a low pressure EGR passage cleaning condition is satisfied. The low pressure EGR passage cleaning condition is, for example, a case where the amount of deposit attached to the low pressure EGR passage 31 exceeds a threshold value. The threshold value is determined as a value that does not have these fears because if the deposit flows into the intake pipe 3 as a large lump, the functions of the turbocharger 5 and the intercooler 8 are reduced. It is also determined by the fact that the low pressure EGR passage 31 does not need to be frequently cleaned.

  For example, the amount of deposit may be simply obtained based on the elapsed time since the flow velocity of the low-pressure EGR gas was increased last time. Alternatively, the relationship between the engine speed and the engine load and the deposit amount may be obtained in advance and mapped, and the deposit amount obtained from the map may be integrated.

  If an affirmative determination is made in step S102, the process proceeds to step S103, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S103, the low pressure EGR valve 32 is opened or fully opened, and the high pressure EGR valve 42 is closed or fully closed rather than being adjusted by the ECU 20. That is, the low pressure EGR gas is easily flowed.

  In step S104, the exhaust throttle valve 11 is fully closed. If the exhaust passage is secured even when the exhaust throttle valve 11 is on the most closed side, the most closed side may be referred to as fully closed.

Due to the processing in step S104, the pressure difference between the exhaust pipe 4 side and the intake pipe 3 side of the low pressure EGR passage 31 is increased, so that the flow rate of the low pressure EGR gas is increased.

  In this way, the flow rate of the low-pressure EGR gas in the low-pressure EGR passage 31 can be increased, so that deposits adhering to the low-pressure EGR passage 31 can be quickly scattered and removed. Further, since the deposit is removed before the deposit increases, it is possible to suppress the functional deterioration of the members provided in the intake pipe 3. In this embodiment, the ECU 20 that executes this routine corresponds to the flow speed increasing means in the present invention.

  In this embodiment, the exhaust throttle valve 11 is closed when the flow rate of the low-pressure EGR gas is increased, but the intake throttle valve 9 may be closed instead of or together with this. That is, in step S104, the intake throttle valve 9 may be closed instead of the exhaust throttle valve 11, or both the exhaust throttle valve 11 and the intake throttle valve 9 may be closed. Also by closing the intake throttle valve 9, the pressure difference between the upstream side and the downstream side of the low pressure EGR passage 31 can be increased, so that the flow rate of the low pressure EGR gas can be increased. The conditions for closing the intake throttle valve 9 are the same as those for closing the exhaust throttle valve 11.

  Further, when only the intake throttle valve 9 is closed, it is not necessary to provide the exhaust throttle valve 11. Further, the exhaust throttle valve 11 may be attached to the exhaust pipe 4 closer to the internal combustion engine 1 than the location where the low pressure EGR passage 31 is connected to the exhaust pipe 4. Even if the exhaust throttle valve 11 is attached in such a place, the pressure difference in the low pressure EGR passage 31 can be increased. Moreover, the selection range of the attachment location of the exhaust throttle valve 11 can be widened.

  Further, when only the exhaust throttle valve 11 is closed, it is not necessary to provide the intake throttle valve 9. Further, the intake throttle valve 9 may be attached to the intake pipe 3 on the internal combustion engine 1 side than the portion where the low pressure EGR passage 31 is connected to the intake pipe 3. Even if the intake throttle valve 9 is attached in such a place, the pressure difference in the low pressure EGR passage 31 can be increased. Moreover, the selection range of the attachment location of the intake throttle valve 9 can be widened.

1 is a diagram illustrating a schematic configuration of an internal combustion engine to which an exhaust gas recirculation device for an internal combustion engine according to an embodiment is applied and an intake / exhaust system thereof. It is the flowchart which showed the flow of flow-rate raise control of the low pressure EGR gas which concerns on an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Intake pipe 4 Exhaust pipe 5 Turbocharger 5a Compressor housing 5b Turbine housing 7 Air flow meter 8 Intercooler 9 Intake throttle valve 10 Filter 11 Exhaust throttle valve 14 Accelerator pedal 15 Accelerator opening sensor 16 Crank position sensor 20 ECU
30 Low pressure EGR device 31 Low pressure EGR passage 32 Low pressure EGR valve 33 Low pressure EGR cooler 40 High pressure EGR device 41 High pressure EGR passage 42 High pressure EGR valve 43 High pressure EGR cooler

Claims (4)

A turbocharger having a turbine in the exhaust passage and a compressor in the intake passage;
A low-pressure EGR passage that connects an exhaust passage downstream of the turbine and an intake passage upstream of the compressor and recirculates part of the exhaust from the internal combustion engine to the intake passage;
EGR gas amount adjusting means for adjusting the amount of EGR gas flowing in the low pressure EGR passage according to the state of the internal combustion engine or the vehicle;
During deceleration of the vehicle, or during fuel cut of the engine, a flow rate rise means for raising than when the flow rate of EGR gas in the low-pressure EGR passage, the amount of EGR gas is adjusted by the EGR gas amount regulating means,
An exhaust gas recirculation device for an internal combustion engine, comprising: A low pressure EGR valve for adjusting the amount of EGR gas flowing through the low pressure EGR passage;
An exhaust throttle valve that adjusts the amount of exhaust gas flowing through the exhaust passage downstream from the location where the low-pressure EGR passage is connected;
An exhaust throttle valve opening adjusting means for adjusting the opening of the exhaust throttle valve according to the state of the internal combustion engine or the vehicle;
Further comprising
The flow rate increasing means increases the flow rate of EGR gas so that the low pressure EGR valve is not fully closed and the opening of the exhaust throttle valve is closed compared to when the exhaust throttle valve opening adjusting means is adjusted. The exhaust gas recirculation apparatus for an internal combustion engine according to claim 1, wherein A low pressure EGR valve for adjusting the amount of EGR gas flowing through the low pressure EGR passage;
An intake throttle valve that adjusts the amount of intake air that flows through the intake passage upstream from the point where the low-pressure EGR passage is connected;
An intake throttle valve opening adjusting means for adjusting the opening of the intake throttle valve according to the state of the internal combustion engine or the vehicle;
Further comprising
The flow rate increasing means increases the flow rate of EGR gas so that the low pressure EGR valve is not fully closed and the opening of the intake throttle valve is more closed than when the intake throttle valve opening adjusting means is adjusted. The exhaust gas recirculation apparatus for an internal combustion engine according to claim 1, wherein A high-pressure EGR passage that connects an exhaust passage upstream of the turbine and an intake passage downstream of the compressor and recirculates part of the exhaust from the internal combustion engine to the intake passage;
A high pressure EGR valve for adjusting the amount of EGR gas flowing through the high pressure EGR passage;
High pressure EGR valve opening degree adjusting means for adjusting the opening degree of the high pressure EGR valve according to the state of the internal combustion engine or the vehicle;
Further comprising
The exhaust of the internal combustion engine according to claim 2 or 3, wherein the flow rate increasing means makes the opening degree of the high pressure EGR valve closer to the closing side than when adjusted by the high pressure EGR valve opening degree adjusting means. Reflux apparatus.

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