JP2009250209A - Exhaust gas recirculating device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress pollution of a supercharger and to secure proper EGR amount, in an exhaust gas recirculating device of an internal combustion engine provided with a variable valve mechanism and the supercharger. <P>SOLUTION: This internal combustion engine 10 is provided with variable valve timing mechanisms 15 and 16 for varying valve opening/closing timing of intake valve and exhaust valve of the internal combustion engine 10, the supercharger 50 for supercharging intake air passing through an intake passage 20, and an EGR device 40 for introducing a part of exhaust gas into the intake passage 20. Upstream side EGR amount introduced into the intake passage 20 through an upstream side EGR passage 41 and downstream side EGR amount introduced into the intake passage 20 through a downstream side EGR passage 42 are adjusted based on the valve opening/closing timing of the variable valve timing mechanisms 15 and 16 to obtain target EGR amount set according to an operation state of the internal combustion engine 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine, which includes a variable valve mechanism that changes the valve opening / closing mode of at least one of an intake valve and an exhaust valve, and a supercharger.

  Conventionally, an internal combustion engine equipped with a supercharger is known to increase the amount of intake air supplied to the combustion chamber of the internal combustion engine. Such a supercharger includes a turbine that is provided in an exhaust passage and rotates by exhaust energy, and a compressor that is provided in an intake passage and rotates as the turbine rotates. The intake air is supercharged by the rotation of the compressor. The As a result, the amount of intake air supplied to the combustion chamber increases, and the engine output can be improved.

  In addition to the above-described supercharger, an internal combustion engine is known that includes an exhaust gas recirculation device (EGR device) that introduces a portion of exhaust gas from the exhaust passage to the intake passage in order to improve exhaust emission. This EGR device includes an exhaust gas recirculation passage (EGR passage) that communicates an exhaust passage and an intake passage of an internal combustion engine, and an exhaust amount control valve (EGR valve) that controls the amount of exhaust gas flowing through the EGR passage. Yes. Then, by adjusting the opening degree of the EGR valve, the amount of exhaust gas introduced into the intake passage (EGR amount) is adjusted based on the differential pressure between the exhaust pipe pressure and the intake pipe pressure. As a result, the EGR amount suitable for the engine operating state is adjusted to lower the combustion temperature in the combustion chamber, so that the amount of nitrogen oxide (NOx) emission can be suppressed.

Here, in an engine equipped with such a supercharger and an EGR device, an EGR passage that communicates an intake passage and an exhaust passage on the downstream side of the compressor is provided, and exhaust gas is exhausted through the EGR passage by using negative suction pressure. It is introduced into the intake passage. However, when the intake air in the intake passage is supercharged by the supercharger, the intake pipe pressure on the downstream side of the compressor rises, so that the exhaust introduction efficiency through the EGR passage decreases. Therefore, a configuration has been proposed in which an upstream EGR passage connected to the upstream side of the compressor in the intake passage and a downstream EGR passage connected to the downstream side of the compressor are provided. For example, in the configuration described in Patent Document 1, exhaust is introduced into the intake passage through the upstream EGR passage when the engine is in the supercharging operation region, and downstream EGR when the engine is in the non-supercharging operation region. By introducing the exhaust gas into the intake passage through the passage, an EGR amount is to be secured even in the supercharging operation region where the intake pipe pressure increases. In addition, by introducing the exhaust into the intake passage through the downstream EGR passage, the exhaust can be prevented from passing through the compressor and the compressor can be prevented from being contaminated.
JP-A-5-256213

  In recent years, variable valve mechanisms that variably set valve characteristics such as valve opening / closing timings and valve lift amounts of intake valves and exhaust valves have been widely adopted in internal combustion engines in order to improve engine output and exhaust emissions. By providing such a variable valve mechanism in an internal combustion engine provided with the above-described supercharger and EGR device, it is expected that further effects can be obtained in terms of engine output improvement and exhaust emission improvement. However, in the configuration in which such a variable valve mechanism is provided, in addition to the supercharging efficiency by the supercharger, the pressure in the intake passage and the pressure in the exhaust passage also vary depending on the valve opening / closing mode by the variable valve mechanism. For this reason, there is a possibility that control to an appropriate EGR amount cannot be performed.

  The present invention has been made in view of such circumstances, and the object thereof is to suppress contamination of the supercharger in an exhaust gas recirculation device for an internal combustion engine including a variable valve mechanism and a supercharger. The purpose is to secure an appropriate amount of EGR.

In the following, means for achieving the above object and its effects are described.
According to a first aspect of the present invention, there is provided a variable valve mechanism that can change a valve opening / closing mode of at least one of an intake valve and an exhaust valve of an internal combustion engine, and a rotary valve that is provided in an exhaust passage of the engine and is rotated by energy of exhaust. Exhaust gas recirculation of an internal combustion engine that is applied to an internal combustion engine that includes a turbine and a turbocharger that is provided in the intake passage and that rotates with the rotation of the turbine, and that introduces part of the exhaust gas into the intake passage In the apparatus, a target EGR amount setting means for setting a target EGR amount to be introduced into the intake passage according to an operating state of the engine, and an upstream side in communication between the upstream side of the compressor and the exhaust passage of the intake passage An EGR passage, a downstream EGR passage that communicates the exhaust passage downstream of the compressor and the exhaust passage, and the target EGR amount setting The upstream EGR amount introduced into the intake passage through the upstream EGR passage and the downstream EGR amount introduced into the intake passage through the downstream EGR passage are obtained in order to obtain the target EGR amount set by the stage. The gist of the present invention is to provide an adjusting means for adjusting based on the valve opening / closing mode by the variable valve mechanism.

  According to the above configuration, the upstream EGR passage that communicates the upstream side of the intake passage compressor and the exhaust passage, the downstream EGR passage that communicates the exhaust passage and the downstream side of the compressor of the intake passage, and the target EGR In order to obtain the target EGR amount set by the setting means, the upstream EGR amount introduced into the intake passage through the upstream EGR passage and the downstream EGR amount introduced into the intake passage through the downstream EGR passage are determined by the variable valve mechanism. Since the adjusting means for adjusting based on the valve opening / closing mode is provided, in an exhaust gas recirculation device applied to an internal combustion engine having a variable valve mechanism and a supercharger, supercharger contamination, particularly compressor contamination, is suppressed. At the same time, an appropriate amount of EGR can be secured.

  For example, even if the supercharging efficiency by the supercharger is the same, the pressure in the intake passage on the downstream side of the compressor may decrease based on the valve opening / closing mode by the variable valve mechanism. In such a case, the downstream EGR amount is increased to suppress contamination of the supercharger. On the other hand, when the pressure in the intake passage on the downstream side of the compressor increases based on the valve opening / closing mode by the variable valve mechanism, the upstream EGR amount can be increased to ensure an appropriate EGR amount. To do. The adjusting means for adjusting the upstream EGR amount and the downstream EGR amount may be a single valve that adjusts both the ratio and the amount of EGR gas flowing through the upstream EGR passage and the downstream EGR passage. The valve may be a combination of a valve that adjusts the ratio of EGR gas flowing through the upstream EGR passage and the downstream EGR passage and a valve that adjusts the amount of EGR gas.

  According to a second aspect of the present invention, in the exhaust gas recirculation apparatus for an internal combustion engine according to the first aspect, an upstream side intake pressure detection means for detecting an intake pressure at a portion of the intake passage where the upstream EGR passage is connected is provided. Further, the adjusting means further adjusts the upstream EGR amount and the downstream EGR amount based on the intake pressure detected by the upstream intake pressure detecting means.

  According to the above configuration, the intake air pressure detecting means for detecting the intake pressure of the portion of the intake air passage where the upstream EGR passage is connected is further provided, and the upstream EGR is based on the intake pressure detected by the upstream intake pressure detecting means. Since the amount and the downstream EGR amount are further adjusted, it is possible to more effectively suppress the contamination of the turbocharger and secure an appropriate EGR amount.

  According to a third aspect of the present invention, in the exhaust gas recirculation device for the internal combustion engine according to the first or second aspect, a downstream side intake pressure detection for detecting an intake pressure at a portion of the intake passage where the downstream EGR passage is connected. The adjusting means further adjusts the upstream EGR amount and the downstream EGR amount based on the intake pressure detected by the downstream intake pressure detecting means.

  According to the above configuration, the intake air passage further includes the downstream intake pressure detection means for detecting the intake pressure at the portion of the intake passage where the downstream EGR passage is connected, and the upstream EGR is based on the intake pressure detected by the downstream intake pressure detection means. Since the amount and the downstream EGR amount are further adjusted, it is possible to more effectively suppress the contamination of the turbocharger and secure an appropriate EGR amount.

  In particular, when the above configuration is applied to the configuration of claim 2, the upstream EGR amount and the downstream EGR amount may be adjusted in consideration of the upstream pressure and the downstream pressure of the compressor in the intake passage. become able to.

  According to a fourth aspect of the present invention, in the exhaust gas recirculation device for an internal combustion engine according to any one of the first to third aspects, the upstream EGR passage and the downstream EGR passage have a common upstream side and a downstream side. The exhaust passage further includes exhaust pressure detection means for detecting an exhaust pressure at a portion of the exhaust passage where a common portion of the upstream EGR passage and the downstream EGR passage is connected, and the adjustment means includes the exhaust pressure The gist is to further adjust the upstream EGR amount and the downstream EGR amount based on the exhaust pressure detected by the detecting means.

  According to the above configuration, the upstream EGR passage and the downstream EGR passage are common on the upstream side and divided on the downstream side, and the exhaust of the portion where the common portion of the upstream EGR passage and the downstream EGR passage connects in the exhaust passage. Exhaust pressure detection means for detecting the pressure is further provided. In order to further adjust the upstream EGR amount and the downstream EGR amount based on the exhaust pressure detected by the exhaust pressure detection means, it is possible to suppress the contamination of the turbocharger and the appropriate EGR amount. Can be more effectively secured.

  In particular, when the above configuration is applied to a configuration having both the configurations of claim 2 and claim 3, the exhaust pressure at the connecting portion of the common portion of the upstream EGR passage and the downstream EGR passage, and the downstream of each of these EGR passages The upstream EGR amount and the downstream EGR amount can be adjusted in consideration of the intake pressure at the connection portion on the side. That is, in addition to the valve opening / closing mode by the variable valve mechanism, the upstream EGR amount and the downstream EGR amount can be set more appropriately based on these pressures.

  Specifically, the variable valve mechanism is a mechanism that variably sets the valve opening / closing timing of at least one of the intake valve and the exhaust valve, as in claim 5, or according to claim 6. In addition, at least one of the intake valve and the exhaust valve may be a mechanism that variably sets the valve lift amount.

  The invention according to claim 7 is the exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 6, wherein the intercooler for cooling the gas flowing in the intake passage is provided in the intake passage. The gist is further provided on the downstream side of the compressor, and the downstream EGR passage is connected to the upstream side of the intercooler of the intake passage.

  According to the above configuration, the intake passage further includes an intercooler that cools the gas flowing in the passage on the downstream side of the compressor, and the downstream EGR passage is connected to the upstream side of the intercooler of the intake passage. Therefore, the exhaust gas introduced into the intake passage through the EGR passage can be cooled by the intercooler.

Hereinafter, an embodiment embodying an exhaust gas recirculation device for an internal combustion engine according to the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing an internal combustion engine to which an exhaust gas recirculation device for an internal combustion engine according to the present embodiment is applied and its peripheral configuration. As shown in the figure, an internal combustion engine 10 includes a supercharger 50 that supercharges intake air of the engine 10 and an exhaust gas recirculation device that introduces a part of the exhaust gas of the engine 10 into the intake passage 20 as EGR gas. (EGR device) 40.

  The internal combustion engine 10 is an in-line four-cylinder engine and is provided with a plurality of cylinders # 1 to # 4. The cylinder head 11 of the engine 10 is provided with fuel injection valves for injecting fuel into the combustion chambers 12 of the cylinders # 1 to # 4 corresponding to the cylinders # 1 to # 4 (not shown). ). Further, the cylinder head 11 is supplied with an intake manifold 21 that distributes intake air supplied through the intake passage 20 to the cylinders # 1 to # 4, and exhaust gas discharged from the combustion chambers 12 of the cylinders # 1 to # 4. An exhaust manifold 31 that is assembled and discharged to the exhaust passage 30 is attached.

  The supercharger 50 includes a compressor 51 provided in the intake passage 20, a turbine 52 provided in the exhaust passage of the exhaust passage 30 and rotated by the energy of the exhaust, and a drive shaft 53 connecting the compressor 51 and the turbine 52. It is configured with. The compressor 51 rotates with the rotation of the turbine 52, whereby the intake air in the intake passage 20 is supercharged. Further, an intercooler 22 for cooling the gas flowing through the intake passage 20 is provided downstream of the compressor 51 in the intake passage 20. As a result, the intake air supercharged by the compressor 51 is cooled by the intercooler 22 and then supplied to the combustion chambers 12 of the cylinders # 1 to # 4 of the engine 10 via the intake manifold 21. In this way, the air-fuel mixture of the intake air supplied to the combustion chambers 12 of the cylinders # 1 to # 4 and the fuel supplied from the fuel injection valves burns in the combustion chambers 12, and the exhaust after combustion becomes the exhaust manifold 31. To be discharged.

  The cylinder head 11 of the internal combustion engine 10 has an intake camshaft 13 provided with an intake cam for opening and closing the intake valve of the engine 10 and an exhaust camshaft 14 provided with an exhaust cam for opening and closing the exhaust valve of the engine 10. Is rotatably supported. At the end portions of the intake camshaft 13 and the exhaust camshaft 14, variable valve timing mechanisms 15 and 16 for variably setting the valve opening / closing timing of the intake valve and the exhaust valve are respectively provided. These variable valve timing mechanisms 15 and 16 are mechanisms for changing the relative rotational phases of the intake camshaft 13 and the exhaust camshaft 14 with respect to the crankshaft that is the engine output shaft, respectively, by hydraulic pressure. The valve opening / closing timings of the intake valve and the exhaust valve are continuously changed. An intake cam angle sensor 17 for detecting the rotation phase (intake cam angle) of the camshaft 13 is attached to the intake camshaft 13, and the rotation phase (exhaust gas) of the camshaft 14 is attached to the exhaust camshaft 14. An exhaust side cam angle sensor 18 for detecting a cam angle) is attached.

  The EGR device 40 introduces EGR gas into the intake passage 20 as an inlet for introducing EGR gas into the upstream side 20U from the compressor 51 and the EGR gas into the downstream side 20L from the compressor 51. A downstream EGR passage 42 is provided. The upstream EGR passage 41 and the downstream EGR passage 42 are common on the upstream side and divided on the downstream side. More specifically, the upstream EGR passage 41 is a passage that connects the upstream side 20U from the compressor 51 of the intake passage 20 to the upstream side 30U from the turbine 52 of the exhaust passage 30, and the downstream EGR passage 42 is This is a passage that communicates the downstream side 20L of the intake passage 20 with respect to the compressor 51 and the upstream side 30U of the exhaust passage 30 with respect to the turbine 52. The EGR passages 41 and 42 are both connected to the upstream side of the intercooler 22 in the intake passage 20. In addition, an EGR valve 43 that adjusts both the ratio and the amount of EGR gas that flows through the upstream EGR passage 41 and the downstream EGR passage 42 is provided at a portion where the upstream EGR passage 41 and the downstream EGR passage 42 are divided. Is provided. Specifically, the EGR valve 43 is a three-way valve that can adjust the opening degree of each opening of the divided parts (downstream side) of the EGR passages 41 and 42, and is a common part of the EGR passages 41 and 42. The amount of EGR gas supplied through (upstream side) is adjusted, and this EGR gas is distributed to the divided portions (downstream side) of the EGR passages 41 and 42. The EGR valve 43 corresponds to a configuration as an adjusting means.

  An air flow meter 23 that detects the amount of intake air flowing through the passage 20 is attached to the most upstream side of the intake passage 20. An upstream intake pressure sensor 24 for detecting an intake pressure (upstream intake pressure) Pinup of the portion 20U is attached to a portion 20U to which the upstream EGR passage 41 is connected in the intake passage 20. The upstream intake pressure sensor 24 corresponds to upstream intake pressure detection means. Further, a downstream intake pressure sensor 25 for detecting an intake pressure (downstream intake pressure) Pinlow of the intake pressure of the portion 20L is attached to a portion 20L of the intake passage 20 to which the downstream EGR passage 42 is connected. The downstream intake pressure sensor 25 corresponds to the downstream intake pressure detection means.

  An exhaust pressure sensor 32 for detecting the exhaust pressure Pex of this portion 30U is attached to a portion 30U where the common portion of the upstream EGR passage 41 and the downstream EGR passage 42 is connected in the exhaust passage 30. The exhaust pressure sensor 32 corresponds to an exhaust pressure detection means.

  In addition to the various sensors described above, the internal combustion engine 10 is provided with various sensors for grasping the operating state of the engine 10. For example, an accelerator pedal depression amount sensor 61 that detects the depression amount of an accelerator pedal (not shown) and a crank angle sensor 62 that detects the crank angle of the engine 10 and detects the engine speed are provided. Then, signals output from various sensors corresponding to the detected values are input to an electronic control device 60 that comprehensively controls various devices of the internal combustion engine 10.

  The electronic control device 60 includes a storage device that stores calculation results of various controls, a function map used for the calculation, and the like in addition to the calculation device and the drive circuit. The electronic control unit 60 grasps the operating state of the internal combustion engine 10 based on output signals from various sensors, controls the fuel injection mode of the fuel injection valve, and the intake valve and the exhaust according to the operating state of the internal combustion engine 10. Various controls such as variable valve timing control for respectively driving the variable valve timing mechanisms 15 and 16 are executed to adjust the valve opening / closing timing of the valves.

By the way, the relationship between the operating state of the internal combustion engine 10 and the EGR amount (requested EGR amount) required in accordance with the operating state is as conceptually shown in FIG.
An area A indicated by a dotted line in the figure is an area corresponding to an idle operation state or a low load operation state, and is a region where the required EGR amount is relatively small. A region C indicated by an alternate long and short dash line is a region corresponding to a low rotation / high load operation state to a high rotation operation state. Basically, the required EGR amount is not so much, but the required intake air amount increases. Thus, the suction negative pressure in the intake passage 20 is reduced.

  A region B indicated by a solid line is a region including mode travel that is relatively frequently used in daily driving, and is a region in which the improvement in fuel efficiency is regarded as important and the required EGR amount is maximized. In the boundary region (shaded region shown in the figure) with the above-described region C, it is required to secure both the intake air amount and the EGR amount. However, since the intake negative pressure is reduced, the introduction of EGR gas is required. Efficiency is reduced. Therefore, the electronic control unit 60 performs EGR gas adjustment control so as to appropriately supply the EGR amount required for the engine 10 to the combustion chamber 12.

  Hereinafter, the EGR gas adjustment control executed by the electronic control unit 60 will be described with reference to FIGS. 3 and 4. This EGR gas adjustment control corresponds to control as “adjustment means”.

  The flowchart shown in FIG. 3 is repeatedly executed by the electronic control device 60 with a predetermined period. In this series of processing, first, a target EGR amount is set (step S100). This target EGR amount corresponds to the above-described required EGR amount, and is determined by referring to the map based on the load of the engine 10 (engine load) and the rotation speed of the engine 10 (engine rotation speed). This map is a map showing the relationship between the engine load and engine speed and the required EGR amount, and is set in advance based on experiments and the like. The load (engine load) of the internal combustion engine 10 is based on the intake air amount detected based on the signal from the air flow meter 23, the accelerator pedal depression amount detected based on the signal from the accelerator pedal depression amount sensor 61, and the like. Be grasped. Further, the rotational speed (engine rotational speed) of the internal combustion engine 10 is detected based on a signal from the crank angle sensor 62. The processing in this step corresponds to processing as target EGR amount setting means.

  Next, the valve opening / closing timings of the intake valve and the exhaust valve are respectively grasped (step S200). Specifically, it is grasped based on signals respectively output from the intake side cam angle sensor 17 and the exhaust side cam angle sensor 18.

  Subsequently, the upstream intake pressure Pinup, the downstream intake pressure Pinlow, and the exhaust pressure Pex are grasped (step S300). Specifically, it is grasped based on signals output from the upstream side intake pressure sensor 24, the downstream side intake pressure sensor 25, and the exhaust pressure sensor 32, respectively.

  Based on the grasped information, the upstream EGR amount and the downstream EGR amount are adjusted (step S400). Specifically, the upstream EGR amount and the downstream EGR amount are adjusted by controlling the valve opening state of the EGR valve 43 so that the target EGR amount set in step S100 is obtained. As a result, the series of processes is completed.

Next, the process (adjustment process) executed in step S400 will be described in detail with reference to FIG.
In this series of processing, first, it is determined whether or not the EGR gas introduction efficiency is lower than the target EGR amount (step S410). Here, the introduction efficiency of EGR gas is low with respect to the target EGR amount, the current valve opening state of the EGR valve 43 introduces into the intake passage 20 an EGR amount that is equal to or larger than the target EGR amount set in step S100. This is equivalent to not being able to open the valve. Specifically, the introduction of EGR gas based on the valve opening / closing timings of the intake valve and the exhaust valve obtained in step S200, the upstream intake pressure Pinup, the downstream intake pressure Pinlow, and the exhaust pressure Pex obtained in step S300. It is determined whether the efficiency is low with respect to the target EGR amount. Such valve opening / closing timing and EGR gas introduction efficiency corresponding to each pressure are set in advance based on experiments and the like.

  By the way, the EGR gas is introduced by using a suction negative pressure in the intake passage 20, that is, a pressure difference between the pressure in the intake passage 20 (intake pipe pressure) and the pressure in the exhaust passage 30 (exhaust pipe pressure). Here, even if the supercharging efficiency of the intake air by the supercharger 50 is the same, if the valve opening / closing timing of the intake valve is changed, the pressure in the intake passage 20 changes, while the valve opening / closing timing of the exhaust valve is changed. As a result, the pressure in the exhaust passage 30 changes. For example, in order to improve the fuel efficiency of the internal combustion engine 10, the intake valve closing timing is substantially advanced or the intake valve closing timing is substantially retarded. In the case where the so-called Atkinson cycle in which the expansion volume is larger than that is employed, the pressure in the intake passage 20 increases while the pressure in the exhaust passage 30 decreases, so the suction negative pressure decreases. . Thereby, the introduction efficiency of EGR gas falls.

  In addition to the valve opening / closing timing of the intake valve and the exhaust valve, EGR gas introduction efficiency is calculated in consideration of the upstream intake pressure Pinup, the downstream intake pressure Pinlow, and the exhaust pressure Pex. That is, based on these pressures, in consideration of the differential pressure at the portion where the upstream EGR passage 41 communicates with the intake passage 20 and the exhaust passage 30, and the differential pressure at the portion where the downstream EGR passage 42 communicates, The introduction efficiency is calculated, and it is determined whether or not the introduction efficiency is lower than the target EGR amount.

  If it is determined through this determination processing that the EGR gas introduction efficiency is lower than the target EGR amount (step S410: YES), it is determined that the EGR amount introduced into the intake passage 20 has not reached the target EGR amount. Therefore, the ratio of the upstream EGR amount is set high (step S420). That is, the ratio of the upstream EGR amount to be introduced to the upstream side 20U from the compressor 51 of the intake passage 20 through the upstream side EGR passage 41 is set higher. The ratio set here is the ratio at which the total EGR amount introduced into the intake passage 20, that is, the EGR amount supplied to the combustion chamber 12 can reach the target EGR amount.

  The pressure on the downstream side 20L of the compressor 51 in the intake passage 20 becomes higher than the pressure on the upstream side 20U due to the operation of the supercharger 50. Here, when the EGR amount introduced into the upstream side 20U of the compressor 51 having the lower pressure, that is, the ratio of the upstream EGR amount is set high, the EGR gas introduction efficiency is improved. Therefore, the upstream EGR amount and the downstream EGR amount are increased. And the total EGR amount, that is, the EGR amount supplied to the combustion chamber 12 is increased. Thereby, an appropriate amount of EGR can be secured.

  On the other hand, if it is determined that the EGR gas introduction efficiency is not lower than the target EGR amount (step S410: NO), the current open state of the EGR valve 43 takes in an EGR amount that is greater than or equal to the target EGR amount. It can be determined that the state can be introduced into the passage 20. Therefore, the ratio of the downstream EGR amount is set high (step S430). That is, the ratio of the downstream EGR amount to be introduced to the downstream side 20L through the downstream side EGR passage 42 to the downstream side 20L of the compressor 51 of the intake passage 20 is set higher. Thereby, it can avoid that EGR gas passes through the compressor 51 of the supercharger 50, and contamination of the supercharger 50, especially the compressor 51, can be suppressed. The ratio set here is set such that the EGR amount introduced into the intake passage 20, that is, the total EGR amount supplied to the combustion chamber 12 can ensure the target EGR amount.

  In addition, since the introduction efficiency of the EGR gas is reduced by setting the ratio of the downstream EGR amount high in this way, the total EGR amount that combines the upstream EGR amount and the downstream EGR amount, that is, the combustion chamber 12 is increased. The amount of EGR supplied is reduced. Here, since the current open state of the EGR valve 43 is a state in which an EGR amount equal to or greater than the target EGR amount can be introduced into the intake passage 20, even if the overall EGR amount is reduced, the target EGR amount is reduced. Can be secured.

  And an EGR valve is adjusted so that it may become the ratio of the amount of EGR set in Step S420 or Step S430 (Step S440). Specifically, the upstream EGR passage 43 is appropriately adjusted by adjusting the valve opening state of the EGR valve 43, that is, the opening degree of each opening portion of the common portion of the upstream EGR passage 41 and the downstream EGR passage 42 and the divided portion. The ratio of the EGR gas flowing through 41 and the downstream EGR passage 42 is set to the set ratio. As a result, the series of processes is completed.

According to the embodiment described above, the following effects can be obtained.
(1) An upstream EGR passage 41 that connects the upstream side 20U of the intake passage 20 with respect to the compressor 51 and the exhaust passage 30, and a downstream side of the intake passage 20 that connects the downstream side 20L and the exhaust passage 30 with each other. And an EGR passage 42. Then, the upstream EGR amount introduced into the intake passage 20 through the upstream EGR passage 41 and the downstream EGR amount introduced into the intake passage 20 through the downstream EGR passage 42 are taken into account by the variable valve timing mechanisms 15, 16. In order to adjust so that the target EGR amount can be obtained based on each valve opening / closing timing, in the configuration including the variable valve timing mechanism (variable valve mechanism) and the supercharger 50, contamination of the supercharger 50, in particular, the compressor 51 Contamination can be suppressed and an appropriate amount of EGR can be secured.

  (2) The intake passage 20 includes an upstream intake pressure sensor 24 that detects an intake pressure (upstream intake pressure) Pinup of a portion 20U to which the upstream EGR passage 41 is connected, and is upstream based on the detected upstream intake pressure Pinup. Since the side EGR amount and the downstream EGR amount are further adjusted, it is possible to more effectively suppress the contamination of the supercharger 50 and ensure an appropriate amount of EGR.

  (3) The intake passage 20 includes a downstream intake pressure sensor 25 that detects an intake pressure (downstream intake pressure) Pinlow of a portion 20L to which the downstream EGR passage 42 is connected, and is upstream based on the detected downstream intake pressure Pinlow. Since the side EGR amount and the downstream EGR amount are further adjusted, it is possible to more effectively suppress the contamination of the supercharger 50 and ensure an appropriate amount of EGR. Further, the upstream EGR amount and the downstream EGR amount are adjusted in consideration of the upstream intake pressure Pinup that is the pressure on the upstream side 20U of the compressor 51 in the intake passage 20 and the downstream intake pressure Pinlow that is the pressure on the downstream side 20L. Will be able to.

  (4) The exhaust passage 30 includes an exhaust pressure sensor 32 that detects the exhaust pressure Pex of the portion 30U to which the common portion of the upstream EGR passage 41 and the downstream EGR passage 42 is connected, and the upstream side based on the detected exhaust pressure Pex. Since the EGR amount and the downstream EGR amount are further adjusted, it is possible to more effectively suppress the contamination of the supercharger 50 and ensure an appropriate EGR amount. Further, in the exhaust passage 30, the exhaust pressure Pex at the connection portion 30 U of the common portion of the upstream EGR passage 41 and the downstream EGR passage 42, the intake pressure at the connection portions 20 U and 20 L on the downstream side of these EGR passages 41 and 42 ( The upstream EGR amount and the downstream EGR amount can be adjusted in consideration of the upstream intake pressure Pinup and the downstream intake pressure Pinlow). In other words, in addition to the valve opening / closing timing by the variable valve timing mechanisms 15 and 16, the upstream EGR amount and the downstream EGR amount can be set more appropriately based on these pressures.

  (5) In the intake passage 20, an intercooler 22 that cools the gas flowing in the passage 20 is provided on the downstream side of the compressor 51, and the upstream EGR passage 41 and the downstream EGR passage 42 are both intake passages. Since the intercooler 22 is connected upstream of the 20 intercoolers 22, the exhaust gas introduced into the intake passage 20 through the EGR passages 41 and 42 can be cooled by the intercooler 22.

(Other embodiments)
The exhaust gas recirculation device for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above embodiment, and may be implemented as the following embodiment, which is appropriately modified from the embodiment. You can also.

  In the above embodiment, an example in which the EGR valve 43 that is a single valve that adjusts both the ratio and the amount of EGR gas flowing through the upstream EGR passage and the downstream EGR passage is provided. Any control valve that can adjust the upstream EGR amount and the downstream EGR amount may be used, and the present invention is not limited to this example. For example, as shown in FIG. 5, EGR valves 73 and 74 are provided in the upstream EGR passage 71 and the downstream EGR passage 72, respectively, and the upstream EGR amount and the downstream EGR amount are adjusted by adjusting the valves 73 and 74, respectively. It may be adjusted so that the target EGR amount is introduced into the intake passage 20.

  Furthermore, it may consist of a combination of a valve for adjusting the ratio of EGR gas flowing through the upstream EGR passage and the downstream EGR passage and a valve for adjusting the amount of EGR gas. Such a valve for adjusting the amount of EGR gas can be provided, for example, in a common part of the upstream EGR passage and the downstream EGR passage. Even in this case, the effects shown in the above (1) to (5) can be achieved.

  In the above embodiment, an example is shown in which both the upstream EGR passage 41 and the downstream EGR passage 42 are connected to the upstream side of the intercooler 22 in the intake passage 20, but only the upstream EGR passage 41 in the intake passage 20 is shown. You may employ | adopt the aspect connected to the upstream of the intercooler 22. FIG. Even in this case, the EGR gas introduced into the intake passage 20 through the upstream EGR passage 41 can be cooled by the intercooler 22.

  The supercharger 50 may be a known variable nozzle vane supercharger, or a supercharger including a bypass passage and a wastegate valve that exhausts exhaust by bypassing the turbine. In this case, the introduction efficiency of the EGR gas may be determined in consideration of the supercharging efficiency of the supercharger that changes depending on such a configuration.

  In the above embodiment, an example is shown in which the upstream side of the upstream EGR passage 41 and the downstream EGR passage 42 are common, but the whole may be formed as a separate passage. Further, the connection location in the exhaust passage 30 may be formed on the downstream side of the turbine 52. However, from the viewpoint of increasing the differential pressure between the intake passage side and the exhaust passage side in these EGR passages, it is desirable to form a connection location upstream of the turbine in the exhaust passage.

  -Although the example which provided the intercooler 22 in the intake passage 20 was shown in the said embodiment, the aspect which does not provide an intercooler is also employable. Even in this case, the effects shown in the above (1) to (4) can be achieved.

  Further, it is possible to adopt a mode in which the EGR gas flowing through the upstream EGR passage and the downstream EGR passage is cooled by the EGR cooler and then introduced into the intake passage. For example, as shown in FIG. 5, in the EGR device 70, an EGR cooler 75 can be provided at a common part of the upstream EGR passage 71 and the downstream EGR passage 72.

  In the above embodiment, the example in which the throttle valve for adjusting the amount of intake air flowing through the intake passage 20 is not provided is shown. However, the throttle valve is provided in the intake passage and another peripheral configuration provided in the intake passage May be changed as appropriate. For example, as shown in FIG. 5, in the intake passage 20, a throttle valve 19 for adjusting the amount of intake air flowing through the passage 20 is provided on the downstream side of the compressor 51, and the downstream EGR passage 72 is connected to the throttle valve 19. You may make it connect with the downstream 200L.

  In the above embodiment, the upstream side intake pressure sensor 24, the downstream side intake pressure sensor 25, and the exhaust pressure sensor 32 are provided, and the target EGR is taken into consideration in consideration of the upstream side intake pressure Pinup, the downstream side intake pressure Pinlow, and the exhaust pressure Pex. An example is shown in which the upstream EGR amount and the downstream EGR amount are adjusted so that the amount is obtained. However, some or all of these sensors can be omitted as appropriate. For example, as shown in FIG. 5, a mode in which these sensors are not provided can be adopted. Even in this case, by adjusting the upstream EGR amount and the downstream EGR amount based on the valve opening / closing timing by the variable valve timing mechanisms 15 and 16 so as to obtain the target EGR amount, the operation shown in the above (1). There is an effect.

  In the above embodiment, the variable valve timing mechanisms 15 and 16 for variably setting the valve opening / closing timings of the intake valve and the exhaust valve are provided as the variable valve mechanism. However, the variable valve mechanism is not limited to this example. A mode in which a variable valve lift amount mechanism for variably setting the valve lift amount of the intake valve and the exhaust valve may be employed. Further, it is possible to adopt a mode in which such a variable valve mechanism is provided in one of the intake valve and the exhaust valve, or a mode in which both the variable valve timing mechanism and the variable valve lift amount mechanism are provided. Even in this case, by adjusting the upstream side EGR amount and the downstream side EGR amount based on the valve opening / closing mode by the variable valve mechanism, it is possible to achieve an effect similar to the effect shown in the above (1).

  -The application object of the present invention may be either a gasoline engine or a diesel engine. In short, the present invention can be applied to any internal combustion engine provided with a variable valve mechanism, a supercharger, and an exhaust gas recirculation device, and it is possible to suppress contamination of the supercharger and ensure an appropriate amount of EGR. become able to.

The schematic diagram which shows an internal combustion engine and its periphery structure about one Embodiment which actualized the exhaust gas recirculation apparatus of the internal combustion engine concerning this invention. The conceptual diagram which divides into the area | region and shows the driving | running state of the internal combustion engine in the embodiment. The flowchart which shows the process sequence of EGR gas adjustment control in the embodiment. The flowchart which shows the process sequence about the adjustment process of the upstream EGR amount and downstream EGR amount in the embodiment. The schematic diagram which shows an internal combustion engine and its periphery structure about other embodiment which actualized the exhaust gas recirculation apparatus of the internal combustion engine concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, # 1- # 4 ... Cylinder, 11 ... Cylinder head, 12 ... Combustion chamber, 13 ... Intake cam shaft, 14 ... Exhaust cam shaft, 15, 16 ... Variable valve timing mechanism, 17 ... Intake side cam angle Sensor 18, exhaust cam angle sensor 19, throttle valve, 20 intake passage, 21 intake manifold, 22 intercooler, 23 air flow meter, 24 upstream intake pressure sensor, 25 downstream intake pressure sensor , 30 ... exhaust passage, 31 ... exhaust manifold, 32 ... exhaust pressure sensor, 40, 70 ... EGR device, 41, 71 ... upstream EGR passage, 42, 72 ... downstream EGR passage, 43, 73, 74 ... EGR valve , 50 ... supercharger, 51 ... compressor, 52 ... turbine, 53 ... drive shaft, 60 ... electronic control device, 61 ... accelerator depression amount sensor, 62 ... kura Click angle sensor.

Claims (7)

A variable valve mechanism for changing a valve opening / closing mode of at least one of an intake valve and an exhaust valve of an internal combustion engine, a turbine that is provided in an exhaust passage of the engine and is rotated by exhaust energy, and is provided in an intake passage. In an exhaust gas recirculation device for an internal combustion engine that is applied to an internal combustion engine that includes a supercharger that has a compressor that rotates as the turbine rotates, and that introduces a portion of exhaust gas into the intake passage.
Target EGR amount setting means for setting a target EGR amount to be introduced into the intake passage in accordance with the operating state of the engine;
An upstream EGR passage communicating the upstream side of the compressor with respect to the compressor and the exhaust passage;
A downstream EGR passage communicating the exhaust passage and the downstream side of the compressor of the intake passage;
The upstream EGR amount introduced into the intake passage through the upstream EGR passage and the downstream side introduced into the intake passage through the downstream EGR passage so that the target EGR amount set by the target EGR amount setting means is obtained. An exhaust gas recirculation device for an internal combustion engine, comprising: adjusting means for adjusting an EGR amount based on the valve opening / closing mode by the variable valve mechanism. The exhaust gas recirculation device for an internal combustion engine according to claim 1,
An upstream side intake pressure detecting means for detecting an intake pressure at a portion of the intake passage to which the upstream EGR passage is connected;
The exhaust gas recirculation apparatus for an internal combustion engine, wherein the adjusting means further adjusts the upstream EGR amount and the downstream EGR amount based on the intake pressure detected by the upstream intake pressure detecting means. The exhaust gas recirculation device for an internal combustion engine according to claim 1 or 2,
Further comprising a downstream side intake pressure detection means for detecting an intake pressure at a portion of the intake passage where the downstream EGR passage is connected;
The exhaust gas recirculation apparatus for an internal combustion engine, wherein the adjusting means further adjusts the upstream EGR amount and the downstream EGR amount based on the intake pressure detected by the downstream intake pressure detecting means. The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 3,
The upstream EGR passage and the downstream EGR passage are common on the upstream side and divided on the downstream side, and the exhaust pressure of the portion of the exhaust passage where the common portion of the upstream EGR passage and the downstream EGR passage is connected Exhaust pressure detection means for detecting
The exhaust gas recirculation device for an internal combustion engine, wherein the adjusting means further adjusts the upstream EGR amount and the downstream EGR amount based on the exhaust pressure detected by the exhaust pressure detecting means. The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 4,
The variable valve mechanism is a mechanism that variably sets the valve opening / closing timing of at least one of the intake valve and the exhaust valve. The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 5,
The variable valve mechanism is a mechanism that variably sets a valve lift amount of at least one of the intake valve and the exhaust valve. An exhaust gas recirculation device for an internal combustion engine, wherein: The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 6,
In the intake passage, further comprising an intercooler for cooling the gas flowing through the passage on the downstream side of the compressor,
The exhaust gas recirculation device for an internal combustion engine, wherein the downstream EGR passage is connected to an upstream side of the intercooler of the intake passage.

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