JP2015121156A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can prevent or suppress the corrosion of a component which is exposed in a combustion chamber while alleviating a malfunction accompanied by the suppression of the stay of a burnt gas in a cylinder.SOLUTION: An ECU 1A comprises a stop indication detection part which functions as a part for detecting a stop indication of an internal combustion engine 50A. The ECU also comprises a determination part which functions as a part of determining whether or not a temperature Tnzl of a nozzle 56a lowers below a dew point Td at a stop of the internal combustion engine 50A, and whether or not dew condensation is generated in the nozzle 56a. Furthermore, the ECU comprises a control part which functions as a part for performing control for suppressing the stay of a burnt gas in a combustion chamber E when it is determined that the dew condensation is generated, and postpones the execution of the control when it is determined that the dew condensation is not generated.

Description

  The present invention relates to a control device for an internal combustion engine.

  In an internal combustion engine, a part exposed to a combustion chamber may be corroded after the engine is stopped due to a component (for example, sulfur oxide) contained in burned gas. In view of such a case, Patent Document 1 describes that scavenging of the cylinder is performed by performing throttle valve opening control when the engine is stopped. Patent Document 2 discloses a technique for reducing exhaust gas remaining in a cylinder by performing valve opening timing of an exhaust valve and controlling an air pump.

JP2013-11228A Japanese Patent Laid-Open No. 2004-27914

  When scavenging in the cylinder is performed by controlling the opening of the throttle valve when the engine is stopped, the engine stop may be delayed every time due to the operation of the throttle valve. Further, when exhaust gas remaining in the cylinder is reduced by controlling the opening timing of the exhaust valve and the air pump, there is a risk that the burden of power energy consumption increases every time the engine is stopped. Thus, there is a possibility that some inconvenience is accompanied by suppressing the in-cylinder residue of burned gas.

  In view of the above problems, the present invention provides an internal combustion engine control device capable of preventing or suppressing corrosion of components exposed to a combustion chamber while reducing inconvenience associated with suppression of in-cylinder residue of burned gas. Objective.

  The present invention relates to a stop instruction detection unit for detecting a stop instruction for an internal combustion engine, and a temperature of a part exposed to a combustion chamber of the internal combustion engine when the stop instruction detection unit detects a stop instruction. A determination unit that determines whether or not condensation occurs below the dew point during stoppage and whether or not condensation occurs on the relevant part, and suppresses remaining burned gas in the combustion chamber when the determination unit determines that condensation occurs The control device of the internal combustion engine includes a control unit that forgoes the execution of the control when the determination unit determines that condensation does not occur.

  ADVANTAGE OF THE INVENTION According to this invention, corrosion of the components exposed to a combustion chamber can be prevented or suppressed, reducing the problem accompanying suppression of the in-cylinder residue of burned gas.

It is a figure which shows 1st ECU with a related structure. It is a schematic block diagram of an internal combustion engine. It is a figure which shows an example of control operation with a flowchart. It is a 1st figure which shows an example of the change of various parameters. It is a 2nd figure which shows an example of the change of various parameters. It is explanatory drawing of 1st residual suppression control. It is a figure which shows 2nd ECU with a related structure. It is explanatory drawing of 2nd residual suppression control.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an ECU 1A that is a first ECU together with related configurations. FIG. 2 is a schematic configuration diagram of the internal combustion engine 50A. FIG. 2 shows a main part of one cylinder of the internal combustion engine 50A. The internal combustion engine 50A is provided with an intake system 10A and an exhaust system 20. The intake system 10A circulates intake air supplied to the combustion chamber E of the internal combustion engine 50A. The intake system 10 </ b> A includes an air flow meter 11, a throttle valve 12, an intercooler 13, a throttle valve 14, and an intake manifold 15.

  The air flow meter 11 measures the amount of intake air. The throttle valve 12 is a first throttle valve and adjusts the intake air amount. The intercooler 13 cools the intake air. The throttle valve 14 is a second throttle valve and adjusts the intake air amount. The intake manifold 15 distributes intake air to each cylinder of the internal combustion engine 50A. The throttle valve 12 and the throttle valve 14 can adjust the intake air amount in consideration of exhaust gas recirculation (hereinafter referred to as EGR).

  The air flow meter 11 is provided upstream of the throttle valve 12. The throttle valve 12 is provided upstream of the intercooler 13. The intercooler 13 is provided upstream of the throttle valve 14. The throttle valve 14 is provided upstream of the intake manifold 15. The intake manifold 15 is connected to the internal combustion engine 50A.

  The exhaust system 20 circulates the exhaust discharged from the combustion chamber E. The exhaust system 20 includes an exhaust manifold 21 and a catalyst device 22. The exhaust manifold 21 collects exhaust discharged from each cylinder of the internal combustion engine 50A. The catalyst device 22 purifies the exhaust gas. The exhaust manifold 21 is connected to the internal combustion engine 50A. The catalyst device 22 is provided downstream of the exhaust manifold 21.

  The catalyst device 22 includes a diesel oxidation catalyst (hereinafter referred to as DOC) 22a and a diesel particulate filter (hereinafter referred to as DPF) 22b. The DOC 22a oxidizes exhaust components such as HC and CO. The DPF 22b collects particulate matter (hereinafter referred to as PM) and oxidizes the collected PM. The DPF 22b is provided downstream of the DOC 22a. For this reason, the exhaust gas whose temperature has been raised by oxidation at the DOC 22a flows into the DPF 22b, whereby the temperature of the DPF 22b is raised.

  The internal combustion engine 50A is provided with a supercharger 30A. The supercharger 30A is provided in the internal combustion engine 50A indirectly by being provided in the intake system 10A and the exhaust system 20. The supercharger 30A is an exhaust driving supercharger, and includes a compressor 31A and a turbine 32.

  The compressor 31A is provided in the intake system 10A. The compressor 31A constitutes a part of the intake system 10A. In the intake system 10 </ b> A, the compressor 31 </ b> A is provided between the throttle valve 12 and the intercooler 13. The turbine 32 is provided in the exhaust system 20. The turbine 32 constitutes a part of the exhaust system 20. In the exhaust system 20, the turbine 32 is provided between the exhaust manifold 21 and the catalyst device 22.

  The compressor 31A compresses intake air by a built-in compressor wheel. The turbine 32 rotates a built-in turbine wheel by exhaust. The compressor wheel and the turbine wheel are connected to each other via a rotating shaft. For this reason, a compressor wheel compresses intake air by rotating according to rotation of a turbine wheel.

  The internal combustion engine 50A is provided with an EGR device 60. The EGR device 60 is provided indirectly to the internal combustion engine 50A by connecting the exhaust system 20 and the intake system 10A. The EGR device 60 is a first external EGR device that recirculates exhaust gas from the exhaust system 20 to the intake system 10A. The EGR device 60 includes an EGR passage 61 and an EGR valve 62.

  The EGR passage 61 connects the exhaust system 20 and the intake system 10A. Specifically, the EGR passage 61 connects a portion of the exhaust system 20 upstream of the turbine 32 and a portion of the intake system 10A downstream of the compressor 31A. A portion of the exhaust system 20 upstream of the turbine 32 is, for example, an exhaust manifold 21. A portion of the intake system 10A downstream of the compressor 31A is, for example, a portion between the throttle valve 14 and the intake manifold 15 in the intake system 10A.

  The EGR valve 62 controls the flow state of the exhaust gas that flows through the EGR passage 61. Specifically, the EGR valve 62 is a flow rate adjusting valve. The EGR valve 62 may be an on-off valve. The EGR valve 62 is provided so as to be interposed in the EGR passage 61.

  An EGR device 70 is provided in the internal combustion engine 50A. The EGR device 70 is provided indirectly to the internal combustion engine 50A by connecting the exhaust system 20 and the intake system 10A. The EGR device 70 is a second external EGR device that recirculates exhaust gas from the exhaust system 20 to the intake system 10A. The EGR device 70 includes an EGR passage 71, an EGR valve 72, and an EGR cooler 73.

  The EGR passage 71 connects the exhaust system 20 and the intake system 10A. Specifically, the EGR passage 71 connects a portion of the exhaust system 20 downstream of the turbine 32 and a portion of the intake system 10A upstream of the compressor 31A. A portion of the exhaust system 20 downstream of the turbine 32 is, for example, a portion of the exhaust system 20 downstream of the catalyst device 22. A portion of the intake system 10A upstream of the compressor 31A is, for example, a portion of the intake system 10A downstream of the throttle valve 12.

  The EGR valve 72 controls the flow state of the exhaust gas that flows through the EGR passage 71. Specifically, the EGR valve 72 is a flow rate adjusting valve. The EGR valve 72 may be an on-off valve. The EGR valve 72 is provided so as to be interposed in the EGR passage 71. The EGR cooler 73 cools the exhaust gas flowing through the EGR passage 71. The EGR cooler 73 is provided in a portion upstream of the EGR valve 72 in the EGR passage 71. The EGR cooler 73 is provided so as to be interposed in the EGR passage 71.

  The EGR device 60 is configured as an external EGR device of high pressure loop specifications by being connected to a portion of the intake system 10A on the downstream side of the compressor 31A. The EGR device 70 is configured as an external EGR device of a ropeless loop specification by being connected to a portion upstream of the compressor 31A in the intake system 10A.

  The internal combustion engine 50A is a multi-cylinder internal combustion engine, specifically a 4-cylinder internal combustion engine. The internal combustion engine 50A is a compression ignition type internal combustion engine. The internal combustion engine 50A may be a spark ignition type internal combustion engine. The internal combustion engine 50A includes a cylinder block 51, a cylinder head 52, a piston 53, an intake valve 54, an exhaust valve 55, an injector 56, and a variable valve operating device 80A.

  A cylinder 51 a is formed in the cylinder block 51. A piston 53 is accommodated in the cylinder 51a. A cylinder head 52 is fixed to the upper surface of the cylinder block 51. The combustion chamber E is formed as a space surrounded by the cylinder block 51, the cylinder head 52 and the piston 53. The cylinder head 52 is formed with an intake port 52a and an exhaust port 52b. The intake port 52 a guides intake air to the combustion chamber E. The exhaust port 52 b discharges burned gas from the combustion chamber E.

  The intake valve 54 and the exhaust valve 55 are provided in the cylinder head 52. The intake valve 54 opens and closes the intake port 52a. The exhaust valve 55 opens and closes the exhaust port 52b. The injector 56 is provided in the cylinder head 52. The injector 56 includes a nozzle 56a. The nozzle 56a has an injection hole for injecting fuel. The nozzle 56 a is exposed to the combustion chamber E. The nozzle 56 a is an example of a component that is exposed to the combustion chamber E.

  The variable valve operating device 80A is provided in the cylinder head 52. The variable valve operating device 80A is configured to be able to change the valve opening timing of the exhaust valve 55. As the variable valve operating device 80A, for example, a valve operating device that changes the opening / closing timing of the exhaust valve 55 by changing the phase of the exhaust camshaft with respect to the phase of the crankshaft can be applied. The variable valve operating device 80A may be a valve operating device that changes the valve opening timing of the exhaust valve 55 by other methods.

  The ECU 1A is an electronic control device, and is an example of a control device for an internal combustion engine. The ECU 1A is electrically connected to the throttle valve 12, the throttle valve 14, the injector 56, the EGR valve 62, the EGR valve 72, and the variable valve operating device 80A as control targets. In addition to the air flow meter 11, a sensor group 90 is electrically connected to the ECU 1A as sensors and switches. The sensor group 90 includes a crank angle sensor used to detect the rotational speed NE of the internal combustion engine 50A, an accelerator opening sensor that makes an acceleration request to the internal combustion engine 50A, a water temperature sensor that detects the cooling water temperature THW of the internal combustion engine 50A, Includes an ignition switch (hereinafter referred to as IGSW). The cooling water temperature THW is, for example, the cooling water temperature at the cooling water outlet of the internal combustion engine 50A. The sensor group 90 further includes sensors that detect atmospheric temperature, pressure, and humidity.

  Next, an example of the control operation of the ECU 1A will be described using the flowchart shown in FIG. The ECU 1A determines whether or not the IGSW has changed from ON to OFF (step S1). In step S1, it is detected through such a determination that the IGSW has changed from ON to OFF. The fact that the IGSW has changed from ON to OFF is an example of an instruction to stop the internal combustion engine 50A. If a negative determination is made, the process returns to step S1. If the determination is affirmative, an instruction to stop the internal combustion engine 50A is detected. The stop of the internal combustion engine 50A is started when an instruction to stop the internal combustion engine 50A is detected.

  If the determination in step S1 is affirmative, the ECU 1A closes the throttle valve 14 and the EGR valve 62 (step S2). This prevents the exhaust from flowing into the cylinder by EGR while the internal combustion engine 50A is stopped. The internal combustion engine 50A is stopped until the rotational speed NE becomes zero after the internal combustion engine 50A is stopped. In step S2, for example, the EGR valve 62 may be already closed. In this case, the valve closing operation of the EGR valve 62 is unnecessary.

  Following step S2, the ECU 1A calculates a dew point Td in the combustion chamber E (step S3). Further, the temperature Tnzl of the nozzle 56a is calculated (step S4). The dew point Td may be a dew point of water, or may be a dew point of an acid generated by condensation of an acid component contained in exhaust gas together with moisture. In calculating the dew point Td, atmospheric temperature, pressure, humidity, and EGR rate can be considered as parameters affecting the dew point Td. The EGR rate is the ratio of the amount of exhaust gas recirculated by EGR to the total amount of gas sucked into the cylinder. In calculating the temperature Tnzl, the load of the internal combustion engine 50A, the cooling water temperature THW, and the distance from the water jacket of the cooling water can be considered as parameters affecting the temperature Tnzl. The dew point Td and the temperature Tnzl may be calculated (estimated) by an appropriate method in addition to a known technique.

  Following step S4, the ECU 1A determines whether or not the temperature Tnzl is lower than the dew point Td (step S5). The determination in step S5 is performed while the internal combustion engine 50A is stopped. The determination in step S5 is an example of a determination that determines whether or not the temperature Tnzl falls below the dew point Td while the internal combustion engine 50A is stopped and condensation occurs on the nozzle 56a. In step S5, for example, it may be determined whether or not the coolant temperature THW is lower than the dew point Td.

  If an affirmative determination is made in step S5, the ECU 1A executes residual suppression control (step S6). The residual suppression control is control for suppressing the combustion gas from remaining in the combustion chamber E. The residual suppression control can be started while the internal combustion engine 50A is stopped. The residual suppression control will be described in detail later. After step S6, this flowchart ends. If a negative determination is made in step S5, this flowchart is terminated. In this case, execution of the residual suppression control is postponed.

  FIG. 4 is a first diagram illustrating an example of changes in various parameters. FIG. 4 shows an example of changes in various parameters when the internal combustion engine 50A is started and stopped when the engine is cold. FIG. 4 shows the temperature Tnzl, the rotational speed NE, and the cooling water temperature THW as various parameters. The predetermined value α indicates the coolant temperature THW when the engine warm-up is completed. When the engine is cold, the cooling water temperature THW is lower than the predetermined value α.

  The internal combustion engine 50A starts at timing t1. For this reason, the rotational speed NE starts to rise from the timing t1. The rotational speed NE rises until the timing t2, and then is kept constant. The temperature Tnzl and the cooling water temperature THW also start to rise from the timing t1. The temperature Tnzl rises rapidly until the timing t2, and then gradually rises at a substantially constant rate. The temperature Tnzl exceeds the dew point Td at the timing t3. Cooling water temperature THW gradually increases at a substantially constant rate from timing t1.

  At timing t4, IGSW is turned from ON to OFF. As a result, the rotational speed NE starts to decrease at timing t4 and becomes zero at timing t5. Between timing t4 and timing t5, the internal combustion engine 50A is stopped. The temperature Tnzl starts to decrease rapidly from the timing t4, and falls below the dew point Td before reaching the timing t5. This is because the thermal capacity of the nozzle 56a is small. Cooling water temperature THW starts to decrease from timing t4.

  FIG. 5 is a second diagram illustrating an example of changes in various parameters. FIG. 5 shows an example of changes in various parameters while the internal combustion engine 50A is stopped. In FIG. 5, the rotational speed NE, the opening degree Ot of the throttle valve 14, the opening degree Oe of the EGR valve 62, and the intake pressure P are shown as various parameters. The intake pressure P is the intake pressure in the intake manifold 15. FIG. 5 shows changes in various parameters in the vicinity of timing t4 after the scale on the horizontal axis is enlarged as compared with the timing chart shown in FIG.

  The EGR valve 62 adjusts the EGR amount according to the opening degree Oe. The throttle valve 14 adjusts the intake air amount according to the opening degree Oe of the EGR valve 62. In this example, the EGR valve 62 is closed before the timing t4. As a result, the opening degree Ot of the throttle valve 14 is also changed. The intake pressure P changes according to the opening degree Ot of the EGR valve 62 and the throttle valve 14. The rotational speed NE starts to gradually decrease from the timing t4. At timing t4, the EGR valve 62 and the throttle valve 14 are closed. As a result, the intake pressure P rapidly decreases from timing t4 and becomes negative pressure.

  FIG. 6 is an explanatory diagram of the first residual suppression control. In step S6 of the flowchart shown in FIG. 3 described above, the ECU 1A specifically executes the first residual suppression control. In the first residual suppression control, the variable valve apparatus 80A is controlled so as to retard the valve opening timing of the exhaust valve 55. The opening timing of the exhaust valve 55 can be retarded so that the exhaust valve 55 does not open until the pressure of the combustion chamber E becomes positive in the exhaust stroke. According to the first residual suppression control, the backflow of burned gas from the exhaust system 20 can be prevented or suppressed. Therefore, the scavenging efficiency of the burned gas from the combustion chamber E can be increased. As a result, it is possible to suppress the combustion gas from remaining in the combustion chamber E.

  As described above with reference to FIG. 3, the ECU 1 </ b> A performs the residual suppression control and defers execution according to the determination result of whether or not condensation occurs. As a result, it is possible to prevent or suppress the corrosion of the nozzle 56a while reducing the inconvenience associated with the suppression of the in-cylinder residual burned gas.

  The internal combustion engine 50A performs EGR with the EGR device 60 and the EGR device 70. EGR is also performed when the engine is cold to improve exhaust emissions. However, when performing EGR, burned gas tends to remain in the cylinder as much as the exhaust gas is introduced into the cylinder by EGR. The internal combustion engine 50A is also stopped when the engine is cold. When the internal combustion engine 50A is stopped when the engine is cold, the temperature Tnzl tends to fall below the dew point Td while the internal combustion engine 50A is stopped due to the heat capacity. As a result, in this case, the probability that acid condensation occurs on the nozzle 56a increases, and the probability that the corrosion of the nozzle 56a occurs increases.

  Therefore, the ECU 1A is suitable when the internal combustion engine 50A provided with the EGR device 60 and the EGR device 70 is an internal combustion engine. The internal combustion engine in this case may be an internal combustion engine provided with an external EGR device, and may be an internal combustion engine provided with at least one of the EGR device 60 and the EGR device 70, for example.

  When the temperature Tnzl falls below the dew point Td during a relatively short period such as when the internal combustion engine 50A is stopped, the temperature Tnzl tends to fall below the dew point Td before the wall temperature of the combustion chamber E due to the heat capacity. As a result, condensation is likely to occur in the nozzle 56a. On the other hand, the rate of decrease in the wall temperature of the combustion chamber E (for example, the surface temperature of the cylinder 51a) is larger than the rate of decrease in the temperature Tnzl due to the large influence of the cooling water.

  For this reason, when the temperature Tnzl does not fall below the dew point Td while the internal combustion engine 50A is stopped, the wall temperature of the combustion chamber E decreases. As a result, the wall temperature of the combustion chamber E is likely to fall below the dew point Td prior to the temperature Tnzl, and condensation is unlikely to occur in the nozzle 56a. In light of the occurrence of such condensation, the ECU 1A is suitable when the part exposed to the combustion chamber E is the nozzle 56a.

  In the flowchart shown in FIG. 3 described above, the ECU 1A functions as a stop instruction detection unit by executing the process shown in step S1. Moreover, it functions as a determination unit by executing the process shown in step S5. Moreover, it functions as a control unit by executing the processing shown in step S6.

  As shown in the case of a negative determination in step S5, the ECU 1A as the control unit defers execution of the residual suppression control when the ECU 1A as the determination unit determines that no condensation occurs. Specifically, the ECU 1A as the control unit performs the first residual suppression control as the residual suppression control.

  ECU1A is equipped with these structures by functioning as a stop instruction | indication detection part, a determination part, and a control part. These configurations may be realized in a plurality of electronic control devices, for example. Therefore, the control device for the internal combustion engine may be realized by a plurality of electronic control devices, for example.

  FIG. 7 is a diagram showing an ECU 1B that is a second ECU together with related components. The configuration related to the ECU 1B is substantially the same as that of the ECU 1A except for the following points. That is, in the case of the ECU 1B, an intake system 10B is provided instead of the intake system 10A. Further, a supercharger 30B is provided instead of the supercharger 30A. An internal combustion engine 50B is provided instead of the internal combustion engine 50A.

  The intake system 10B is substantially the same as the intake system 10A except for the following points. That is, the intake system 10 </ b> B further includes a bypass passage 16, a switching valve 17, and a switching valve 18. The intake system 10B is provided with a compressor 31B instead of the compressor 31A.

  The bypass passage 16 bypasses the intercooler 13. The bypass passage 16 connects a portion on the upstream side of the intercooler 13 and a portion on the downstream side of the intercooler 13 in the intake system 10B. Specifically, the bypass passage 16 connects a portion of the intake system 10B between the compressor 31B and the intercooler 13 and a portion between the throttle valve 14 and the intake manifold 15.

  The switching valve 17 is a first switching valve and is provided so as to be interposed in the bypass passage 16. The switching valve 18 is a second switching valve, and is provided in a portion between the upstream side connecting portion of the bypass passage 16 and the intercooler 13 in the intake system 10B. The switching valve 17 and the switching valve 18 set the distribution destination of intake air to the intercooler 13 or the bypass passage 16. The switching valve 17 and the switching valve 18 may further set the distribution destination of the intake air to the intercooler 13 and the bypass passage 16. Specifically, the switching valve 17 and the switching valve 18 are flow control valves. The switching valve 17 may be an on-off valve. The same applies to the switching valve 18.

  The supercharger 30B is substantially the same as the supercharger 30A, except that the compressor 31B is provided instead of the compressor 31A. The compressor 31B is substantially the same as the compressor 31A except that the compressor 31B is configured as follows. That is, the compressor 31B is configured to compress the air, which is a gas, and supply it to the internal combustion engine 50B by further rotating the compressor wheel with the supplied power.

  The compressor 31B, which also serves as the compressor of the exhaust drive supercharger, is advantageous in terms of cost because it does not require a new compressor. However, the compressor 31B does not necessarily have to be configured so as to also serve as a compressor of an exhaust driving supercharger. The compressor 31B may be an electric compressor that compresses a gas by operating with supplied power and supplies the compressed gas to the internal combustion engine 50B.

  The internal combustion engine 50B is substantially the same as the internal combustion engine 50A, except that the variable valve device 80B is provided instead of the variable valve device 80A. The variable valve apparatus 80B is substantially the same as the variable valve apparatus 80A except that the valve opening timing of the intake valve 54 can be changed. The variable valve operating device 80B can be a variable valve operating device 80A that further includes a valve operating device that changes the opening / closing timing of the intake valve 54, for example, by changing the phase of the intake camshaft with respect to the phase of the crankshaft. . The variable valve operating device 80B may be a valve operating device that changes the valve opening timing of the intake valve 54 and the exhaust valve 55 by other methods.

  The ECU 1B is an example of a control device for an internal combustion engine. The ECU 1B is substantially the same as the ECU 1A except for the following points. In other words, the compressor 31B, the switching valve 17 and the switching valve 18 are further electrically connected as control objects to the ECU 1B. Further, a variable valve apparatus 80B is electrically connected as a control object instead of the variable valve apparatus 80A.

  The ECU 1B can operate according to the flowchart shown in FIG. For this reason, illustration of an example of the control operation of the ECU 1B is omitted. Similarly to ECU 1A, ECU 1B also functions as a stop instruction detection unit, a determination unit, and a control unit. In the case of the ECU 1B, the second residual suppression control described below is executed in step S6 of the flowchart shown in FIG. Therefore, ECU1B as a control part performs 2nd residual suppression control specifically, as residual suppression control.

  FIG. 8 is an explanatory diagram of the second residual suppression control. In the second residual suppression control, when a stop instruction is detected, the internal combustion engine 50B is set such that the piston 53 stops at a position where it does not interfere with the intake valve 54 and the exhaust valve 55 in all cylinders of the internal combustion engine 50B. Stop. The position that does not interfere with the intake valve 54 and the exhaust valve 55 is, for example, the center position of the top dead center and the bottom dead center of the piston 53. In the second residual suppression control, the variable valve apparatus 80B is controlled so that the intake valve 54 and the exhaust valve 55 are opened after the internal combustion engine 50B is stopped. Further, the switching valve 17 is opened, the switching valve 18 is closed, and the compressor 31B is operated.

  According to the second residual suppression control, compressed air can be supplied to the combustion chamber E. And it can suppress that burnt gas remains in the combustion chamber E by scavenging the combustion chamber E with the supplied compressed air. According to the second residual suppression control, the temperature of the nozzle 56 a can be increased by supplying the compressed air heated by the compression to the combustion chamber E.

  Similar to the ECU 1A, the ECU 1B performs the residual suppression control and postpones the execution according to the determination result of whether or not condensation occurs. As a result, it is possible to reduce inconveniences associated with suppression of in-cylinder residue of burned gas while preventing or suppressing corrosion of the nozzle 56a. The ECU 1B can also prevent or suppress the corrosion of the nozzle 56a by preventing or suppressing the occurrence of condensation itself by the temperature rise by the compressed air.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

  The part exposed to the combustion chamber may be, for example, an intake valve or an exhaust valve.

ECU 1A, 1B
Intake system 10A, 10B
Exhaust system 20
Supercharger 30A, 30B
Compressor 31A, 31B
Internal combustion engine 50A, 50B
Intake valve 54
Exhaust valve 55
Injector 56
Nozzle 56a
Variable valve gear 80A, 80B

Claims (1)

A stop instruction detector for detecting a stop instruction of the internal combustion engine;
Whether or not the temperature of the part exposed to the combustion chamber of the internal combustion engine falls below the dew point during the stop of the internal combustion engine and condensation occurs on the part when the stop instruction detection unit detects the stop instruction A determination unit for determining
When the determination unit determines that condensation occurs, the control is performed to suppress the combustion gas from remaining in the combustion chamber, and when the determination unit determines that no condensation occurs, the control is performed. A control device for an internal combustion engine, comprising:

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