JP2016211532A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that can suitably suppress leakage of intake air to an exhaust passage via an exhaust gas recirculation passage.SOLUTION: This device includes: a supercharger having an exhaust turbine; a bypass passage for communicating an exhaust upstream side portion and an exhaust downstream side portion of the exhaust turbine in an exhaust passage with each other; a waste gate valve for closing the bypass passage; an EGR passage for communicating the exhaust passage and an intake passage with each other; and an EGR valve for closing the EGR passage. When the electronic control device detects the start of a valve closing operation of the waste gate valve (t13), by starting a valve closing operation of the EGR valve, during supercharging by using the supercharger, the waste gate valve and the EGR valve are closed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device for an internal combustion engine provided with a supercharger and an exhaust gas recirculation device.

  Conventionally, it is often used to provide a supercharger having an exhaust turbine in an internal combustion engine (see, for example, Patent Document 1). The internal combustion engine described in Patent Literature 1 includes a bypass passage that communicates an exhaust upstream portion and an exhaust downstream portion of an exhaust turbine in an exhaust passage, and a waste gate valve that closes the bypass passage. The internal combustion engine described in Patent Document 1 includes an exhaust gas recirculation (EGR) device that recirculates exhaust gas in the exhaust passage to the intake passage. This EGR device includes an EGR passage that connects an exhaust passage and an intake passage of an internal combustion engine, and an EGR valve that closes the EGR passage.

JP 2012-97639 A

  In an internal combustion engine provided with a supercharger and an EGR device, the intake pressure (so-called intake manifold pressure) in the intake air downstream side of the compressor in the intake passage becomes higher than the compressor in the intake passage during supercharging by the turbocharger. As a result, part of the intake air in the intake passage may flow backward in the EGR passage and leak into the exhaust passage. In order to avoid such leakage of intake air, it is conceivable to close the EGR valve when the intake manifold pressure becomes high due to supercharging by the supercharger.

  It takes time until the EGR valve is in a state of closing the EGR passage (valve closed state) after the EGR valve closing operation is started. Therefore, even if the EGR valve closing operation is started when the intake manifold pressure becomes high, the leakage of the intake air to the exhaust passage through the EGR passage is not performed until the EGR valve is closed. It may occur.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for an internal combustion engine that can suitably suppress the leakage of intake air to the exhaust passage via the exhaust recirculation passage. is there.

  An internal combustion engine control apparatus for achieving the above object includes a supercharger having an exhaust turbine provided in an exhaust passage of the internal combustion engine, an exhaust upstream portion of the exhaust turbine and an exhaust downstream side of the exhaust passage. A bypass passage communicating with the portion, a waste gate valve closing the bypass passage, an exhaust recirculation passage communicating the exhaust passage and the intake passage of the internal combustion engine, and an exhaust recirculation closing the exhaust recirculation passage. A circulation valve. The control device includes: a valve closing detection unit that detects the start of the valve closing operation of the waste gate valve; and a valve closing detector that detects the start of the valve closing operation when the valve closing detection unit detects the valve closing operation. And a valve control unit that closes the waste gate valve and the exhaust gas recirculation valve at the time of supercharging by the supercharger by starting the operation.

  According to the above apparatus, when the start of the closing operation of the waste gate valve is detected, the closing operation of the exhaust gas recirculation (EGR) valve can be started without waiting for the subsequent increase in the intake pressure. . Therefore, if the EGR valve is in the open state, the EGR valve can be closed before the intake manifold pressure becomes high enough to cause leakage of intake air through the EGR passage. Therefore, it is possible to suitably suppress the intake air from leaking into the exhaust passage through the EGR passage when supercharging is performed by the supercharger.

  In the control apparatus, a pressure detection unit that detects an intake pressure downstream of the compressor of the supercharger in the intake passage is provided. When the intake pressure detected by the pressure detector during the closing operation of the exhaust gas recirculation valve is equal to or lower than a predetermined pressure, the valve control unit has a predetermined opening different from the fully closed opening When the intake pressure detected by the pressure detector during the closing operation of the exhaust recirculation valve is higher than the predetermined pressure, the opening of the exhaust gas recirculation valve is changed. Preferably, the opening degree of the exhaust gas recirculation valve is changed to the fully closed opening degree.

  When the timing at which the EGR valve is closed becomes earlier, the period for executing the exhaust gas recirculation to the intake passage through the EGR passage is shortened accordingly, so that the amount of exhaust gas recirculated into the intake passage (EGR Amount) will decrease.

  According to the above apparatus, when the intake manifold pressure is not so high during the closing operation of the EGR valve, that is, the exhaust gas can be recirculated to the intake passage through the EGR passage, and the exhaust passage through the EGR passage can be recirculated. When there is no risk of leakage of the intake air, the opening of the EGR valve is less than a predetermined opening that is different from the fully-closed opening (the opening at which the valve is closed) (predetermined opening or more than the predetermined opening). (The opening degree on the valve closing side). At this time, since the EGR valve can be opened with the predetermined opening as the limit opening on the valve opening side, the exhaust gas can be recirculated to the intake passage via the EGR passage. Therefore, the EGR amount can be increased as compared with a device that changes the opening degree of the EGR valve to the fully closed opening degree without using the intake manifold pressure. In addition, since the EGR valve can be closed to an opening equal to or less than a predetermined opening at this time, the opening of the EGR valve is subsequently operated when the EGR valve is operated to close the EGR valve. Can be promptly changed to the fully closed position. According to the above apparatus, when the intake manifold pressure is high during the closing operation of the EGR valve, the opening degree of the EGR valve is changed to the fully closed opening degree, and the leakage of the intake air to the exhaust passage through the EGR passage is prevented. It can suppress suitably.

1 is a schematic diagram showing a schematic configuration of a control device for an internal combustion engine according to a first embodiment. The flowchart which shows the execution procedure of the EGR valve closing process of the first embodiment. (A)-(d) is a timing chart which shows an example of the execution aspect of the EGR valve closing process of 1st Embodiment. The flowchart which shows the execution procedure of the EGR valve closing process of 2nd Embodiment. (A)-(e) is a timing chart which shows an example of the execution aspect of the EGR valve closing process of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment of a control device for an internal combustion engine will be described.
As shown in FIG. 1, in the intake passage 11 of the internal combustion engine 10, the compressor 21 of the supercharger 20, the intercooler 12 that cools the intake air, and the cross-sectional area of the intake passage 11 are changed in order from the intake upstream side. A throttle valve 13 is attached. An exhaust turbine 22 of the supercharger 20 and an exhaust purification device 15 for purifying exhaust are attached to the exhaust passage 14 of the internal combustion engine 10 in order from the exhaust upstream side. In the supercharger 20, a compressor wheel 21 </ b> A provided inside the compressor 21 and a turbine wheel 22 </ b> A provided inside the exhaust turbine 22 are connected.

  The internal combustion engine 10 is provided with an EGR device 30 for returning a part of the exhaust gas in the exhaust passage 14 to the intake passage 11 as exhaust gas recirculation (EGR) gas. The EGR device 30 is an EGR passage that communicates a portion of the exhaust passage 14 upstream of the exhaust turbine 22 with respect to the exhaust passage 22 and a portion of the intake passage 11 downstream of the intake side of the throttle valve 13 as a passage for recirculating EGR gas. 31 is provided. An EGR valve 32 for adjusting the amount of EGR gas passing through the EGR passage 31 and an EGR cooler 33 for cooling the EGR gas are attached to the EGR passage 31. Then, through the operation control of the EGR valve 32, the amount of EGR gas passing through the EGR passage 31, that is, the EGR amount by the EGR device 30 is adjusted.

  Further, the internal combustion engine 10 is provided with a waste gate valve mechanism 40 for bypassing the exhaust turbine 22. The waste gate valve mechanism 40 includes a bypass passage 41 that connects a portion of the exhaust passage 14 on the exhaust upstream side of the exhaust turbine 22 and a portion of the exhaust downstream side, and a waste gate valve 42 that closes the bypass passage 41. Yes. The waste gate valve 42 is connected to a diaphragm type actuator 43 that is operated by a differential pressure acting on a built-in diaphragm, and the actuator 43 has a differential pressure control for adjusting the differential pressure acting on the diaphragm. A valve 44 is connected. Then, through the operation control of the differential pressure control valve 44, the opening degree of the waste gate valve 42 is controlled, and the amount of exhaust discharged through the bypass passage 41 is adjusted.

  The internal combustion engine 10 is provided with various sensors for detecting the operating state. As various sensors, for example, a speed sensor 61 for detecting the rotational speed (engine rotational speed NE) of the output shaft (not shown) of the internal combustion engine 10 and the opening degree of the throttle valve 13 (throttle opening degree TA) are detected. And an opening sensor 63 for detecting the opening of the EGR valve 32 (EGR opening EA). Further, an accelerator sensor 64 for detecting the operation amount of the accelerator operation member 16 (accelerator operation amount ACC) and an intake pressure (intake manifold pressure P) in a portion of the intake passage 11 on the downstream side of the intake side of the throttle valve 13 are detected. A pressure sensor 65 is provided as a pressure detection unit. In addition, an opening sensor 66 for detecting the opening of the waste gate valve 42 (the waste gate opening WA) is also provided.

  The internal combustion engine 10 is provided with an electronic control device 60 that includes, for example, a microcomputer as a peripheral device. The electronic control device 60 takes in the output signals of various sensors and performs various calculations based on the output signals, and controls the operation of the throttle valve 13, the EGR valve 32, and the waste gate valve 42 according to the calculation results. Various controls relating to the operation of the internal combustion engine 10 are executed. In the present embodiment, the electronic control device 60 corresponds to a valve closing detection unit and a valve control unit.

  The operation control (throttle control) of the throttle valve 13 is executed as follows. That is, the control target value (target throttle opening degree Tta) of the opening degree of the throttle valve 13 is calculated based on the accelerator operation amount ACC and the engine speed NE. Then, the operation of the throttle valve 13 is controlled so that the target throttle opening degree Tta and the actual throttle opening degree TA coincide with each other.

  Further, the operation control (EGR control) of the EGR valve 32 is executed as follows. That is, the control target value (target EGR opening degree Tea) of the opening degree of the EGR valve 32 is calculated based on the engine load and the engine speed NE. Then, the operation of the EGR valve 32 is controlled so that the target EGR opening degree Tea matches the actual EGR opening degree EA. In the present embodiment, as the engine load, a value (= GA / NE) obtained by dividing the intake air amount GA of the internal combustion engine 10 calculated based on the intake manifold pressure P and the engine rotational speed NE by the engine rotational speed NE is used. . As the engine load, an intake air amount GA, a fuel injection amount Q, or a value obtained by dividing the fuel injection amount Q by the engine rotational speed NE (= Q / NE) can also be used.

  In the present embodiment, EGR is performed in an engine operation region in which supercharging by the supercharger 20 is not performed (specifically, a low load low rotation operation region in which the intake air amount GA is small and the engine rotational speed NE is low). The valve 32 is opened, and the EGR gas is recirculated to the intake passage 11 by the EGR device 30. On the other hand, in the engine operation region where the supercharger 20 performs supercharging (specifically, the high load operation region where the intake air amount GA is large and the high rotation operation region where the engine rotational speed NE is high), the EGR valve 32 is When the valve is closed, the EGR gas is not recirculated to the intake passage 11 by the EGR device 30.

  The operation control (waste gate valve control) of the waste gate valve 42 is executed as follows. That is, the control target value (target intake manifold pressure Tp) of the intake manifold pressure P is calculated based on the accelerator operation amount ACC and the engine rotational speed NE. Then, the operation amount of the differential pressure control valve 44 is feedback-controlled so that the target intake manifold pressure Tp and the intake manifold pressure P coincide with each other, and the opening degree of the waste gate valve 42 is adjusted. In this embodiment, in the engine operation region where the supercharger 20 performs supercharging (specifically, the high load operation region where the intake air amount is large or the high rotation operation region where the engine rotational speed NE is high), the waste gate is used. The valve 42 is closed, and the discharge of exhaust gas through the bypass passage 41 is stopped. On the other hand, in the engine operation region where the supercharger 20 is not supercharged (specifically, the low load low rotation operation region where the intake air amount is small and the engine rotational speed NE is low), the waste gate valve 42 is opened. The exhaust is allowed to be discharged through the bypass passage 41.

  In the present embodiment, the EGR valve 32 is closed in the operation region in which the supercharging by the supercharger 20 is performed and the intake manifold pressure P is increased through the execution of the EGR control. Accordingly, it is possible to prevent a part of the intake air in the intake passage 11 from flowing backward through the EGR passage 31 and leaking into the exhaust passage 14 due to the increased intake manifold pressure P.

  Here, it takes some time for the EGR valve 32 to be in a state of closing the EGR passage 31 (closed state) after the EGR valve 32 starts to close. Therefore, when the intake manifold pressure P suddenly rises at the time of acceleration or the like, the EGR valve 32 is closed even if the EGR valve 32 starts the closing operation at the timing when the intake manifold pressure P becomes high. The intake manifold pressure P rises until it reaches the state, and there is a risk that intake air leaks into the exhaust passage 14 via the EGR passage 31. Such leakage of the intake air into the exhaust passage 14 is not preferable because it causes various inconveniences such as occurrence of misfire in the internal combustion engine 10, deterioration of drivability, and acceleration failure.

  In the internal combustion engine 10, the waste gate valve 42 does not block the bypass passage 41 when the engine operating region shifts from the non-supercharging region to the supercharging region, for example, during acceleration due to the operation of the accelerator operation member 16. The state (valve open state) is shifted to a state (valve closed state) in which the bypass passage 41 is closed.

  In view of this point, in the present embodiment, it is detected whether or not the waste gate valve 42 has started to close when the engine operation region shifts from the non-supercharging region to the supercharging region. When the start of the closing operation of the waste gate valve 42 is detected, the closing operation of the EGR valve 32 is started. Through the execution of the waste gate valve control and the EGR control, the waste gate valve 42 and the EGR valve 32 are closed during supercharging by the supercharger 20.

Hereinafter, the process for closing the EGR valve 32 in this way (EGR valve closing process) will be described in detail.
FIG. 2 shows an execution procedure of the EGR valve closing process. The series of processes shown in the flowchart of FIG. 5 conceptually shows the execution procedure of the EGR valve closing process, and the actual process is executed by the electronic control unit 60 as an interrupt process at predetermined intervals. The EGR valve closing process is executed as a part of the EGR control process.

As shown in FIG. 2, in this process, first, the waste gate opening WA is detected by the opening sensor 66 (step S11), and whether or not both of the following (condition A) and (condition B) are satisfied. Is determined (step S12).
(Condition 1) The waste gate valve 42 is being closed. Specifically, the waste gate opening WA is changing to the opening on the valve closing side.
(Condition b) The opening degree of the waste gate valve 42 is changed from an opening degree larger than the judgment opening degree JV1 to an opening degree below the judgment opening degree JV1. Specifically, the waste gate opening WA detected at the previous execution of this process is larger than the determination opening JV1, and the waste gate opening WA detected at the previous execution of this process is equal to or less than the determination opening JV1. about. Note that, as the determination opening JV1, an opening that is slightly smaller than the maximum opening (full opening) in the opening control range is determined in advance.

  If both (Condition A) and (Condition B) are satisfied (Step S12: YES), it is determined that the closing operation of the waste gate valve 42 has been started, and the minimum opening (fully closed) in the opening control range is assumed. Opening) is set as the target EGR opening Tea (step S13). In this case, the fully closed opening is set as the target EGR opening Tea until the EGR valve 32 is closed.

On the other hand, if neither of (Condition A) and (Condition B) is satisfied (Step S12: NO), the process ends without executing the process of Step S13.
(Function)
Hereinafter, an operation by executing the EGR valve closing process will be described.

  In the example shown in FIG. 3, before the time t11, the operating state of the internal combustion engine 10 is a stable state in which the throttle opening TA (FIG. 3A) is constant. Further, the EGR valve 32 (FIG. 3C) is in a closed state, and the exhaust gas recirculation (FIG. 3B) through the EGR passage 31 is not executed. Furthermore, since the operating region of the internal combustion engine 10 is a region where supercharging by the supercharger 20 is not performed, the waste gate valve 42 (FIG. 3D) is fully opened.

  At time t11, when the engine operation region becomes an operation region in which the EGR valve 32 is opened, the EGR valve 32 is opened. After time t11, a target EGR opening degree Tea (shown by a one-dot chain line in FIG. 3) is calculated based on the engine operating state, and the operation of the EGR valve 32 is performed based on the target EGR opening degree Tea. Be controlled.

  At a subsequent time t12, the accelerator operation member 16 is operated for acceleration. As a result, the throttle opening degree TA increases after time t12. At this time, since the target intake manifold pressure Tp increases as the accelerator operation amount ACC increases, the valve closing operation of the waste gate valve 42 (FIG. 3D) is performed so as to increase the actual intake manifold pressure P accordingly. Is started.

  At time t13, the waste gate opening WA is an opening larger than the determination opening JV1 to an opening not more than the determination opening JV1 (determination opening JV1 or an opening closer to the valve closing side than the determination opening JV1). . At this time, it is detected that (Condition A) and (Condition B) are both satisfied, and that the closing operation of the waste gate valve 42 is started. Then, the fully closed opening degree is set as the target EGR opening degree Tea on the assumption that there is a high possibility that supercharging by the supercharger 20 will be actually started thereafter. Thereby, the valve closing operation of the EGR valve 32 is started. As described above, according to the present embodiment, when the start of the closing operation of the waste gate valve 42 is detected, the closing operation of the EGR valve 32 is started without waiting for the subsequent increase in the intake manifold pressure P. Can do.

  After time t13, the EGR valve 32 is quickly closed to the fully closed opening. Therefore, when it is assumed that the EGR valve 32 is in the open state, at a timing (time t14) before the intake manifold pressure P becomes high enough to cause leakage of intake air to the exhaust passage 14 via the EGR passage 31. The EGR valve 32 can be closed. Therefore, according to the present embodiment, it is possible to suitably prevent the intake air from leaking into the exhaust passage 14 via the EGR passage 31 when the supercharger 20 performs supercharging.

As described above, according to the present embodiment, the following effects can be obtained.
(1) During supercharging by the supercharger 20, it is possible to suitably suppress the intake air from leaking into the exhaust passage 14 via the EGR passage 31.

(Second Embodiment)
Hereinafter, a second embodiment of the control device for an internal combustion engine will be described focusing on differences from the first embodiment.

This embodiment differs from the first embodiment only in the execution procedure of the EGR valve closing process.
Hereinafter, the EGR valve closing process of the present embodiment will be described. In addition, below, the same code | symbol is attached | subjected and shown to the structure same as 1st Embodiment, and the detailed description is omitted.

  FIG. 4 shows an execution procedure of the EGR valve closing process. The series of processes shown in the flowchart of FIG. 5 conceptually shows the execution procedure of the EGR valve closing process, and the actual process is executed by the electronic control unit 60 as an interrupt process at predetermined intervals. The EGR valve closing process is executed as a part of the process related to EGR control.

  As shown in FIG. 4, in this process, first, the waste gate opening WA is detected by the opening sensor 66 and the intake manifold pressure P is detected by the pressure sensor 65 (step S21). It is determined whether or not both of the conditions (b) are satisfied (step S12).

  If both (Condition A) and (Condition B) are satisfied (Step S12: YES), it is determined whether the intake manifold pressure P is higher than the predetermined pressure JP, assuming that the closing operation of the waste gate valve 42 is started. Is determined (step S23). As the predetermined pressure JP, a constant pressure slightly lower than the atmospheric pressure is determined in advance and stored in the electronic control unit 60.

  When the intake manifold pressure P is equal to or lower than the predetermined pressure JP, the target EGR opening degree Tea is calculated based on the engine load and the engine rotational speed NE, and the calculated target EGR opening degree Tea is fully closed and opened. Guard processing is performed with a predetermined opening JV2 different from the degree as a limit opening on the valve opening side (step S24). Specifically, when the target EGR opening degree Tea calculated based on the engine load and the engine rotational speed NE is equal to or larger than the predetermined opening degree JV2, the predetermined opening degree JV2 is set as a new target EGR opening degree Tea. . On the other hand, when the target EGR opening degree Tea calculated based on the engine load and the engine speed NE is less than the predetermined opening degree JV2, the target EGR opening degree Tea calculated at this time is set as the target EGR opening degree Tea as it is. It is done.

  In the present embodiment, based on the results of various experiments and simulations, the waste gate opening WA is within a control range in which exhaust gas can be recirculated through the bypass passage 41, and the intake manifold pressure P is set to a predetermined value. When the pressure becomes higher than the pressure JP, a control range of the waste gate opening WA that can quickly close the EGR valve 32 and appropriately suppress the leakage of the intake air to the exhaust passage 14 is required. The opening corresponding to the upper limit of the control range is stored in advance in the electronic control unit 60 as the predetermined opening JV2.

  On the other hand, when the intake manifold pressure P is higher than the predetermined pressure JP, the minimum opening (fully closed opening) in the opening control range is set as the target EGR opening Tea (step S25). In this case, the fully closed opening is set as the target EGR opening Tea until the EGR valve 32 is closed.

  In addition, when one of (Condition A) and (Condition B) is not satisfied (Step S12: NO), the process ends without executing Steps S23 to S25.

(Function)
Hereinafter, an operation by executing the EGR valve closing process will be described.
In the example shown in FIG. 5, before the time t21, the operating state of the internal combustion engine 10 is a stable state in which the throttle opening degree TA (FIG. 5 (a)) is constant. Further, the EGR valve 32 (FIG. 5C) is in a closed state, and the exhaust gas recirculation (FIG. 5B) through the EGR passage 31 is not executed. Furthermore, since the operating region of the internal combustion engine 10 is a region where supercharging by the supercharger 20 is not performed, the waste gate valve 42 (FIG. 5 (d)) is fully opened. Further, since the supercharger 20 is not supercharged, the intake manifold pressure P (FIG. 5 (e)) is low.

  At time t21, when the engine operation region becomes an operation region in which the EGR valve 32 is opened, the EGR valve 32 is opened. After time t21, a target EGR opening degree Tea (indicated by a one-dot chain line in FIG. 5) is calculated based on the engine operating state, and the operation of the EGR valve 32 is performed based on the target EGR opening degree Tea. Be controlled.

  At a subsequent time t22, the accelerator operation member 16 is operated for acceleration. As a result, the throttle opening degree TA increases after time t22. At this time, since the target intake manifold pressure Tp increases as the accelerator operation amount ACC increases, the valve closing operation of the waste gate valve 42 is started so as to increase the actual intake manifold pressure P accordingly.

  At time t23, the waste gate opening WA becomes an opening smaller than the determination opening JV1 from an opening larger than the determination opening JV1. At this time, it is detected that (Condition A) and (Condition B) are both satisfied, and that the closing operation of the waste gate valve 42 is started. After that, it is highly likely that supercharging by the supercharger 20 will actually start, and the closing of the EGR valve 32 is started. Specifically, since the intake manifold pressure P is lower than the predetermined pressure JP at this time, the opening degree of the EGR valve 32 is changed with the predetermined opening degree JV2 as the limit opening degree on the valve opening side. Thus, in this example, after the EGR valve 32 is closed to the predetermined opening degree JV2 (time t23 to t24), the opening degree of the EGR valve 32 is maintained at the predetermined opening degree JV2 (after time t24).

  Here, if the timing at which the EGR valve 32 is closed becomes earlier, the period during which the exhaust gas is recirculated to the intake passage 11 via the EGR passage 31 is shortened accordingly, so that the EGR valve 32 is recirculated to the intake passage 11. The amount of exhaust gas (EGR amount) is reduced.

  According to the present embodiment, when the intake manifold pressure P is not so high during the closing operation of the EGR valve 32, that is, the exhaust gas can be recirculated to the intake passage 11 via the EGR passage 31, and the EGR passage When there is no risk of leakage of intake air to the exhaust passage 14 via 31, the opening of the EGR valve 32 is changed to an opening of a predetermined opening JV2 or less. At this time, since the EGR valve 32 can be opened with the predetermined opening JV2 as the limit opening on the valve opening side, the exhaust gas is recirculated to the intake passage 11 via the EGR passage 31. it can. Therefore, the EGR amount can be increased as compared with a device that changes the opening degree of the EGR valve 32 to the fully closed opening degree without using the intake manifold pressure P.

  When the intake manifold pressure P becomes higher than the predetermined pressure JP at time t25, the fully closed opening is set as the target EGR opening Tea. As a result, after time t25, the EGR valve 32 is quickly closed to the fully closed opening. In the present embodiment, when the intake manifold pressure P is lower than the predetermined pressure JP, the EGR valve 32 can be closed to an opening of the predetermined opening JV2 or less, and thereafter the intake manifold pressure P is equal to or higher than the predetermined pressure JP. Thus, when the EGR valve 32 is operated to close the EGR valve 32, the opening degree of the EGR valve 32 can be quickly changed to the fully closed opening degree.

  Then, by closing the EGR valve 32 in this manner, intake air leaks to the exhaust passage 14 via the EGR passage 31 when the EGR valve 32 is assumed to be open. At a timing (time t26) before the intake manifold pressure P increases, the EGR valve 32 can be closed. Therefore, according to the present embodiment, it is possible to suitably prevent the intake air from leaking into the exhaust passage 14 via the EGR passage 31 when the supercharger 20 performs supercharging.

As described above, according to the present embodiment, in addition to the effect described in (1) above, the effect described in (2) below can be obtained.
(2) When the intake manifold pressure P is equal to or lower than the predetermined pressure JP during the valve closing operation of the EGR valve 32, the EGR valve 32 has a predetermined opening JV2 different from the fully closed opening as a limit opening on the valve opening side. When the intake manifold pressure P is higher than the predetermined pressure JP during the closing operation of the EGR valve 32, the EGR valve 32 is closed to the fully closed opening degree. Therefore, the EGR amount can be increased as compared with a device that changes the opening degree of the EGR valve 32 to the fully closed opening degree without using the intake manifold pressure P. In addition, since the EGR valve 32 can be closed to an opening degree equal to or less than the predetermined opening degree JV2 when the intake manifold pressure P is equal to or lower than the predetermined pressure JP during the closing operation of the EGR valve 32, the EGR valve is thereafter closed. When operating to bring the valve 32 into the closed state, the opening degree of the EGR valve 32 can be quickly changed to the fully closed opening degree. When the intake manifold pressure P is high during the closing operation of the EGR valve 32, the opening degree of the EGR valve 32 is changed to the fully closed opening degree, and the leakage of the intake air to the exhaust passage 14 via the EGR passage 31 is prevented. It can suppress suitably.

(Other embodiments)
Each of the above embodiments may be modified as follows.
The start of the closing operation of the waste gate valve 42 may be determined based on the change in the waste gate opening WA from the fully closed opening. Specifically, in the process of step S12 of the EGR valve closing process, the waste gate opening WA at the previous execution of the process is the fully closed opening, and the waste gate opening WA at the current execution of the process. It may be determined whether or not the opening is on the valve opening side with respect to the fully closed opening.

  -The start of the closing operation of the waste gate valve 42 is detected by a change in a parameter other than the waste gate opening WA, such as a control command value of the differential pressure control valve 44 or a differential pressure of the diaphragm of the actuator 43. Can do. For example, the control command value of the differential pressure control valve 44 is smaller than a predetermined value (a value where the waste gate opening WA is smaller than the determination opening JV1), and a value greater than a predetermined value (the waste gate opening WA is determined open). It can be determined that the valve closing operation of the waste gate valve 42 has started. In addition, a value greater than a predetermined value (a waste gate opening WA is a determination opening JV1) from a value where the differential pressure of the diaphragm of the actuator 43 is smaller than a predetermined value (a value where the waste gate opening WA is smaller than the determination opening JV1). It can be determined that the valve closing operation of the waste gate valve 42 has started with the change to the above value.

  As the actuator of the waste gate valve 42, an electric rotary motor or the like can be adopted.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Intercooler, 13 ... Throttle valve, 14 ... Exhaust passage, 15 ... Exhaust gas purification device, 16 ... Accelerator operating member, 20 ... Supercharger, 21 ... Compressor, 21A ... Compressor Wheel, 22 ... Exhaust turbine, 22A ... Turbine wheel, 30 ... EGR device, 31 ... EGR passage, 32 ... EGR valve, 33 ... EGR cooler, 40 ... Waste gate valve mechanism, 41 ... Bypass passage, 42 ... Waste gate valve, DESCRIPTION OF SYMBOLS 43 ... Actuator, 44 ... Differential pressure control valve, 60 ... Electronic control unit, 61 ... Speed sensor, 62, 63, 66 ... Opening sensor, 64 ... Accelerator sensor, 65 ... Pressure sensor.

Claims (2)

A supercharger having an exhaust turbine provided in an exhaust passage of the internal combustion engine;
A bypass passage communicating the exhaust upstream portion and the exhaust downstream portion of the exhaust turbine in the exhaust passage;
A waste gate valve for closing the bypass passage;
An exhaust gas recirculation passage communicating the exhaust passage and the intake passage of the internal combustion engine;
An exhaust gas recirculation valve for closing the exhaust gas recirculation passage;
A valve closing detector for detecting the start of the valve closing operation of the waste gate valve;
By starting the valve closing operation of the exhaust gas recirculation valve when the valve closing detection unit detects the start of the valve closing operation, the waste gate valve and the exhaust gas recirculation at the time of supercharging by the supercharger. A control device for an internal combustion engine, comprising: a valve control unit that closes the valve. The control apparatus for an internal combustion engine according to claim 1,
A pressure detector that detects an intake air pressure downstream of the compressor of the supercharger in the intake passage;
The valve control unit opens a predetermined opening that is different from the fully closed opening when the intake pressure detected by the pressure detector during the closing operation of the exhaust gas recirculation valve is equal to or lower than a predetermined pressure. The opening of the exhaust gas recirculation valve is changed as a limit opening on the valve side, and when the intake pressure detected by the pressure detector during the closing operation of the exhaust gas recirculation valve is higher than the predetermined pressure, A control apparatus for an internal combustion engine, wherein the opening degree of the exhaust gas recirculation valve is changed to the fully closed opening degree.

Images