JP2009191745A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily reduce emission of white smoke during a cold engine state in a control device for an internal combustion engine. <P>SOLUTION: A sufficient valve overlap period is set while increasing back pressure by closing an exhaust throttle valve 24 and a variable nozzle 22c during start of a diesel engine 10. The valve overlap period is set to a period shorter than that during start after completion of start (after complete explosion determination). The exhaust throttle valve 24 is opened and opening of the variable nozzle 22c is reduced after the completion of start. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  Conventionally, for example, Patent Document 1 discloses a start control device for an internal combustion engine with a turbocharger that includes a variable nozzle mechanism that adjusts an exhaust flow rate to a turbine. In this conventional control device, at the time of cold start, the variable nozzle mechanism is adjusted so as to reduce the nozzle passage area, and the back pressure is increased so that a large amount of combustion gas exists in the cylinder of the internal combustion engine. At this time, the valve overlap amount is increased.

Japanese Patent Laid-Open No. 2007-100700 JP 2005-240750 A JP 11-294219 A

  However, even after the internal combustion engine starts to rotate stably after the complete explosion (after the start is completed), the back pressure is increased with the valve overlap amount increased as in the conventional technique described above. The adverse effect of worsening combustion due to the lack of new air amount due to the increase in the internal EGR gas amount may be greater than the effect of increasing the in-cylinder temperature due to the increase in the internal EGR gas amount. In other words, an excessive increase in the internal EGR gas after the start is completed causes a worsening of combustion, and increases the emission of white smoke (THC) when cold.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can satisfactorily reduce the emission of white smoke during cold weather.

A first invention is a control device for an internal combustion engine,
A variable valve mechanism for varying a valve overlap period in which an intake valve opening period and an exhaust valve opening period overlap;
Back pressure variable means for changing the back pressure of the internal combustion engine;
A starting overlap period setting means for controlling the variable valve mechanism to set the valve overlap period during the start of the internal combustion engine;
A starting back pressure control means for increasing back pressure using the back pressure variable means during the start;
Start completion time determination means for determining the start completion time of the internal combustion engine;
A post-startup overlap period setting means for setting the valve overlap period in a shorter period than before reaching the start completion time after reaching the start completion time;
It is characterized by providing.

The second invention is the first invention, wherein
A supercharger capable of supercharging an internal combustion engine;
A post-startup supercharging pressure control means for increasing the supercharging pressure of the internal combustion engine by using the supercharger after reaching the start completion time, compared with before reaching the start completion time;
Is further provided.

The third invention is the second invention, wherein
The turbocharger is a turbocharger having a variable nozzle for adjusting the flow rate of exhaust gas supplied to a turbine,
The post-startup supercharging pressure control means includes post-startup nozzle opening degree control means for controlling at least the opening degree of the variable nozzle after reaching the start completion time point.

Moreover, 4th invention is set in 3rd invention,
The back pressure variable means is the variable nozzle,
The starting back pressure control means includes a starting nozzle opening control means for controlling the opening of the variable nozzle to be small during the starting.

According to a fifth invention, in any one of the second to fourth inventions,
The supercharger is a turbocharger,
The back pressure variable means is disposed in an exhaust passage downstream of the turbine of the turbocharger, and includes an exhaust throttle valve that adjusts an exhaust gas flow rate,
The starting back pressure control means is means for increasing back pressure by performing at least control for closing the exhaust throttle valve during the starting,
The post-startup supercharging pressure control means sets the opening of the exhaust throttle valve to an opening on the opening side as compared with before reaching the start completion time after reaching the start completion time. It includes valve opening setting means.

According to a sixth invention, in any one of the first to fifth inventions,
The after-start overlap period setting means controls at least one of the opening timing of the intake valve and the closing timing of the exhaust valve so that the opening timing of the intake valve is a timing after exhaust top dead center, and the exhaust valve The valve overlap period after reaching the start completion time is set by creating a state in which the closing timing of the engine is later than the opening timing of the intake valve.

  According to the first aspect, after reaching the start completion time point, the valve overlap period is set shorter than that during the start. As a result, the amount of internal EGR gas can be reduced as compared with that during start-up, a decrease in the amount of new air can be prevented, and the supercharging pressure can be increased. For this reason, it is possible to increase the actual compression ratio of the internal combustion engine, and it is possible to increase the in-cylinder temperature (compression end temperature) while avoiding deterioration of combustion after the start is completed. Thereby, generation | occurrence | production of white smoke can be reduced favorably at the time of cold.

  According to the second invention, the actual compression ratio can be increased by increasing the supercharging pressure after reaching the start completion point, and the in-cylinder temperature (compression end temperature) is increased while avoiding deterioration of combustion. It becomes possible. Thereby, it is possible to prevent white smoke during the cold after the start is completed.

  According to the third aspect, by controlling the opening of the variable nozzle after reaching the start completion time, the turbo rotational speed can be increased and the boost pressure can be increased after the start is completed.

  According to the fourth aspect of the invention, the internal EGR gas amount can be sufficiently increased during the start-up by sufficiently controlling the opening of the variable nozzle while the valve overlap period is set. Also, it is possible to prevent the deterioration of combustion accompanying the decrease in the compression end temperature.

  According to the fifth aspect, the turbo rotation speed can be increased by lowering the exhaust pressure downstream of the turbocharger by opening the exhaust throttle valve after reaching the start completion point. Thereby, after completion of starting, the supercharging pressure can be increased while reducing the amount of internal EGR gas.

  According to the sixth aspect of the present invention, the internal EGR gas is prevented from being cooled by avoiding the burned gas from being blown back into the intake passage, and only the warm gas remaining in the cylinder is used as the internal EGR gas. be able to. For this reason, it is possible to increase the supercharging pressure by increasing the new air amount while ensuring only the internal EGR gas that contributes to the increase in the in-cylinder temperature after the start is completed.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes a four-cycle diesel engine (compression ignition internal combustion engine) 10. It is assumed that the diesel engine 10 is mounted on a vehicle and used as a power source. Although the diesel engine 10 of the present embodiment is an in-line four-cylinder type, the number of cylinders and the cylinder arrangement of the diesel engine in the present invention are not limited to this.

  Each cylinder of the diesel engine 10 is provided with an injector 12 that injects fuel directly into the cylinder. The injectors 12 of each cylinder are connected to a common common rail 14. In the common rail 14, high-pressure fuel pressurized by the supply pump 16 is stored. Then, fuel is supplied from the common rail 14 to the injectors 12 of each cylinder. The exhaust gas discharged from each cylinder is collected by the exhaust manifold 18 and flows into the exhaust passage 20.

  The diesel engine 10 includes a variable nozzle type turbocharger 22. The turbocharger 22 includes a turbine 22a that is operated by the exhaust energy of the exhaust gas, and a compressor 22b that is integrally connected to the turbine 22a and is driven to rotate by the exhaust energy of the exhaust gas that is input to the turbine 22a. ing. Further, the turbocharger 22 has a variable nozzle (VN) 22c for adjusting the flow rate of the exhaust gas supplied to the turbine 22a.

  The variable nozzle 22c can be opened and closed by an actuator (not shown) (for example, an electric motor). When the opening of the variable nozzle 22c is reduced, the inlet area of the turbine 22a is reduced, and the flow rate of the exhaust gas blown to the turbine 22a can be increased. As a result, the rotational speeds of the compressor 22b and the turbine 22a (hereinafter referred to as “turbo rotational speed”) are increased, so that the supercharging pressure can be increased. Conversely, when the opening of the variable nozzle 22c is increased, the inlet area of the turbine 22a is increased, and the flow rate of the exhaust gas blown to the turbine 22a is decreased. As a result, the turbo rotation speed decreases, so that the supercharging pressure can be reduced.

  The turbine 22 a of the turbocharger 22 is disposed in the exhaust passage 20. An exhaust throttle valve 24 for limiting the flow rate of the exhaust gas flowing through the exhaust passage 20 is disposed in the exhaust passage 20 on the downstream side of the turbine 22a.

  An air cleaner 28 is provided near the inlet of the intake passage 26 of the diesel engine 10. The air sucked through the air cleaner 28 is compressed by the compressor 22 b of the turbocharger 22 and then cooled by the intercooler 30. The intake air that has passed through the intercooler 30 is distributed by the intake manifold 32 and flows into each cylinder.

  An intake throttle valve 34 is installed between the intercooler 30 and the intake manifold 32 in the intake passage 26. An air flow meter 36 for detecting the intake air amount is installed in the intake passage 26 near the downstream of the air cleaner 28.

  One end of an EGR passage 38 is connected to the intake passage 26 in the vicinity of the intake manifold 32. The other end of the EGR passage 38 is connected to the exhaust manifold 18 of the exhaust passage 20. In the present system, a part of the exhaust gas (burned gas) can be recirculated to the intake passage 26 through the EGR passage 38, that is, external EGR (Exhaust Gas Recirculation) can be performed.

  An EGR cooler 40 for cooling the exhaust gas (EGR gas) passing through the EGR passage 38 is provided in the middle of the EGR passage 38. An EGR valve 42 is provided downstream of the EGR cooler 40 in the EGR passage 38. By changing the opening degree of the EGR valve 42, the amount of exhaust gas passing through the EGR passage 38, that is, the amount of external EGR gas can be adjusted.

  Further, the system of the present embodiment includes an accelerator opening sensor 44 that detects the amount of depression of the accelerator pedal (accelerator opening) of the vehicle on which the diesel engine 10 is mounted, a water temperature sensor 46 that detects the engine coolant temperature, An intake pressure sensor 48 that detects an intake manifold pressure (intake pressure), an exhaust pressure sensor 50 that detects an exhaust manifold pressure (exhaust pressure), and an ECU (Electronic Control Unit) 60 are further provided. The ECU 60 is connected to the various sensors and actuators described above. The ECU 60 controls the operating state of the diesel engine 10 by operating each actuator according to a predetermined program based on the output of each sensor.

  FIG. 2 is a view showing a cross section of one cylinder of the diesel engine 10 in the system shown in FIG. Hereinafter, the diesel engine 10 will be further described. As shown in FIG. 2, a crank angle sensor 72 that detects a rotation angle of the crankshaft 70, that is, a crank angle, is attached in the vicinity of the crankshaft 70 of the diesel engine 10. The crank angle sensor 72 is connected to the ECU 60. The ECU 60 can also calculate the engine speed based on the detection signal of the crank angle sensor 72.

  The diesel engine 10 also includes an intake variable valve mechanism 76 that varies the valve opening characteristic of the intake valve 74 and an exhaust variable valve mechanism 80 that varies the valve opening characteristic of the exhaust valve 78. The specific configurations of the intake variable valve mechanism 76 and the exhaust variable valve mechanism 80 are not particularly limited, and the phase variable mechanism of the phase variable mechanism that continuously varies the opening / closing timing by changing the phase of the camshaft. In addition, a mechanism for driving the cam with an electric motor, an electromagnetically driven valve, a hydraulically driven valve, or the like can be used. Further, an intake cam angle sensor 82 and an exhaust cam angle sensor 84 for detecting the rotation angles of the respective cam shafts, that is, the intake cam angle and the exhaust cam angle, are arranged in the vicinity of the intake cam shaft and the exhaust cam shaft, respectively. Has been. These sensors 82 and 84 are connected to the ECU 60. The ECU 60 can also calculate the advance amount of the opening / closing timing of the intake valve 74 and the exhaust valve 78 based on the detection signals of these sensors 82 and 84.

  According to the intake variable valve mechanism 76 and the exhaust variable valve mechanism 80, a valve overlap period (hereinafter simply referred to as a “valve overlap period”) in which the valve opening period of the exhaust valve 78 and the valve opening period of the intake valve 74 overlap. ) Can be changed.

  In the system of the present embodiment configured as described above, the back pressure of the diesel engine 10 is reduced by narrowing the opening of the variable nozzle (VN) 22c of the turbocharger 22 and the opening of the exhaust throttle valve 24. Can be increased. If the VN 22c and the exhaust throttle valve 24 are throttled in a state where the valve overlap period is secured by the variable valve mechanisms 76 and 80, the exhaust gas recirculation from the exhaust passage 20 into the cylinder is utilized. The amount of internal EGR gas can be increased. Moreover, if such internal EGR gas is increased, the in-cylinder temperature of the diesel engine 10 can be increased satisfactorily.

[Operation when starting internal combustion engine]
FIG. 3 is a diagram showing how the engine speed changes when the diesel engine 10 is started. When starting the diesel engine 10, as shown in FIG. 3, first, cranking is performed by the operation of a starter motor (not shown). Then, as the combustion of the diesel engine 10 is started after the first explosion during cranking, the engine speed increases. Thereafter, when the diesel engine 10 reaches a complete explosion state (a state in which the diesel engine 10 is capable of independently and stably rotating), the starting operation of the diesel engine 10 is completed. It should be noted that the engine speed is maintained at the idling speed while a request to increase the load of the diesel engine 10 is not issued after the start operation is completed.
In addition, as shown in FIG. 3, the period from the cranking start time (that is, the start time) to the complete explosion determination time (that is, the start time) of the diesel engine 10 is referred to as “starting”. ing.

[Challenges during cold operation in low compression ratio diesel engines]
By the way, there is an attempt to improve fuel efficiency by reducing the friction (friction loss) of the diesel engine by reducing the compression ratio of the diesel engine to 16 or less, for example. The diesel engine 10 of the present embodiment is also a diesel engine with such a low compression ratio. In such a low compression ratio diesel engine, there is a problem that the amount of white smoke (THC) emission is likely to increase during cold including start-up. The problem will be described below with reference to FIG.

FIG. 4 is a graph showing the in-cylinder temperature and the new air amount of the diesel engine in relation to the residual gas amount (internal EGR gas amount).
In the diesel engine having a low compression ratio as described above, as shown in FIG. 4A, the in-cylinder temperature (compression end temperature) decreases due to the low compression ratio (ε). For this reason, during start-up (particularly during cold start), combustion becomes unstable, and the amount of white smoke (THC) emission tends to increase. Further, from FIG. 4A, in the diesel engine having a low compression ratio, in order to obtain the same in-cylinder temperature as that of the conventional high compression ratio diesel engine, the compression ratio has been increased. It can be seen that more residual gas (internal EGR gas) is required than a diesel engine. The “necessary in-cylinder temperature” referred to here means an in-cylinder temperature that can stabilize the combustion of the diesel engine.

  The new air amount decreases as the residual gas amount in the cylinder increases. For this reason, in a diesel engine with a low compression ratio, in a state where the in-cylinder temperature necessary for combustion is secured by increasing the internal EGR gas, the compression ratio is increased as shown in FIG. Compared to a diesel engine, new air volume tends to be insufficient.

  For this reason, in a diesel engine with a low compression ratio, a valve overlap period is required to ensure the required in-cylinder temperature at light loads such as idling after the diesel engine 10 starts to rotate stably after a complete explosion. When the back pressure is increased in a sufficiently set state, the combustion worsens due to the shortage of new air amount due to the increase in the internal EGR gas amount, rather than the effect of increasing the in-cylinder temperature due to the increase in the residual gas (internal EGR gas) amount The harmful effect of this may become larger. In other words, an excessive increase in the internal EGR gas after the start is completed causes a worsening of combustion, and increases the emission of white smoke (THC) when cold.

[Characteristics of Embodiment 1]
FIG. 5 is a time chart for explaining characteristic control executed when the diesel engine 10 is started in the cold state in the first embodiment of the present invention.
In the present embodiment, first, during start-up (that is, before reaching the start-up completion time), as shown in FIG. 5B, the opening degree (VNT opening degree) of the variable nozzle 22c is sufficiently closed (for example, all As shown in FIG. 5C, the exhaust throttle valve 24 is closed to a predetermined opening. Further, during start-up, the valve overlap period is set sufficiently long as shown in FIG.

  On the other hand, after the start (that is, after reaching the start completion point), as shown in FIG. 5C, the exhaust throttle valve 24 is opened to the fully open position, and then as shown in FIG. In addition, in order to obtain a sufficient boost pressure increase effect, the opening of the variable nozzle 22c is maintained at a sufficiently closed opening (for example, a fully closed opening). Further, after the start, as shown in FIG. 5D, the valve overlap period is made shorter than the valve overlap period during the start.

FIG. 6 is a flowchart of a routine executed by the ECU 60 in order to realize the above function.
In the routine shown in FIG. 6, first, the engine speed Ne and the engine coolant temperature are read based on the outputs of the crank angle sensor 72 and the water temperature sensor 46, respectively (step 100).

  Next, based on the engine coolant temperature, it is determined whether or not the current operation state of the diesel engine 10 is a cold state (step 102). As a result, if it is determined that the engine is not in the cold state, that is, if it is determined that the diesel engine 10 is already warmed up, this routine is immediately terminated.

  On the other hand, if it is determined in step 102 that the engine is cold, it is then determined whether or not the diesel engine 10 is being started (step 104). More specifically, in step 104, after the start of the starting operation of the diesel engine 10, the diesel engine 10 is completed when the engine speed Ne is maintained at a speed equal to or higher than the predetermined speed over a predetermined time. It is determined that it is in an explosion state (that is, in a start completion state), and a state in which this complete explosion determination has not yet been made is considered as starting.

  If it is determined in step 104 that the diesel engine 10 is being started, the exhaust throttle valve 24 is closed to a predetermined opening in order to increase the in-cylinder temperature by increasing the residual gas (internal EGR gas). At the same time, the opening of the variable nozzle 22c is controlled to the fully closed opening (step 106). In step 106, the valve overlap period is set to be sufficiently long. By such control, in this step 106, the residual gas is greatly increased so that the in-cylinder temperature can be increased until the temperature at which combustion deterioration is eliminated.

  On the other hand, when it is determined in step 104 that the diesel engine 10 is not being started, that is, when it is a light load at which it is determined that the start (complete explosion) has been completed, the turbo speed is increased. Thus, in order to increase the supercharging pressure, the exhaust throttle valve 24 is controlled to a fully open position, and the opening of the variable nozzle 22c is controlled to a small opening (for example, a fully closed position) as in the start. (Step 108). In step 108, the valve overlap period is set to a shorter period than the valve overlap period set during start-up in order to increase the new air amount by reducing the internal EGR gas amount.

  In step 108, the internal EGR gas amount is reduced in the following manner. That is, the valve overlap period is set by a method in which the closing timing of the exhaust valve 78 is delayed from the opening timing of the intake valve 74 while the opening timing of the intake valve 74 is set to a timing after exhaust top dead center. .

  According to the routine shown in FIG. 6 described above, the opening of the exhaust throttle valve 24 and the opening of the variable nozzle 22c are respectively throttled during startup when the diesel engine 10 is in a cold state. The valve overlap period is set longer. As a result, in the diesel engine 10 with a reduced compression ratio, the amount of internal EGR gas can be sufficiently increased during start-up, and it is possible to prevent the deterioration of combustion caused by the decrease in the compression end temperature. Generation of (THC) can be reduced.

  Further, according to the above routine, the valve overlap period is set shorter after completion of the start (during cold light load) than during start. As a result, the amount of internal EGR gas can be reduced as compared with that during start-up, a decrease in the amount of new air can be prevented, and the supercharging pressure can be increased. For this reason, it is possible to increase the actual compression ratio of the diesel engine 10 and to increase the in-cylinder temperature (compression end temperature) while avoiding deterioration of combustion after the start is completed. Thereby, generation | occurrence | production of white smoke can be reduced favorably at the time of cold.

  Further, according to the above routine, after the start is completed, the closing timing of the exhaust valve 78 is delayed from the opening timing of the intake valve 74 in a state where the opening timing of the intake valve 74 is a timing after exhaust top dead center. In the method, the valve overlap period is set short. Thereby, it is possible to prevent the internal EGR gas from being cooled by preventing the burned gas from being blown back to the intake manifold 32, and only the warm gas remaining in the cylinder can be used as the internal EGR gas. For this reason, it is possible to increase the supercharging pressure by increasing the new air amount while securing only the internal EGR gas that contributes to the rise in the in-cylinder temperature.

  Further, according to the above routine, after the start is completed, the exhaust throttle valve 24 is set to the fully open position. Thereby, the turbo rotation speed can be increased by lowering the exhaust pressure downstream of the turbocharger 22. Thereby, after completion of starting, the supercharging pressure can be increased while reducing the amount of internal EGR gas. By increasing the supercharging pressure by such control, it is possible to prevent white smoke due to an increase in the actual compression ratio in the cold state, as described above.

  Further, according to the above routine, even after the start is completed, the opening of the variable nozzle 22c is sufficiently throttled as in the start. Thereby, turbo rotation speed can be raised and a supercharging pressure can be raised. By increasing the supercharging pressure by such control, it is possible to prevent white smoke due to an increase in the actual compression ratio in the cold state, as described above.

  By the way, in the first embodiment described above, both the exhaust throttle valve 24 and the variable nozzle 22c are throttled in order to increase the back pressure during startup. However, the actuator controlled to increase the back pressure during startup may be either the exhaust throttle valve 24 or the variable nozzle 22c.

  In Embodiment 1 described above, the boost pressure is increased by making the amount of exhaust energy given to the turbine 22a of the turbocharger 22 different from that during start-up after the start-up is completed. However, the method of increasing the supercharging pressure after reaching the start completion point in the present invention is not limited to this. For example, the method of electrically driving the compressor of the turbocharger or the shaft torque of the internal combustion engine It may be a supercharger used.

  In the first embodiment described above, the valve overlap period is adjusted by using both the intake variable valve mechanism 76 and the exhaust variable valve mechanism 80. The adjustment may be performed by adjusting either the opening timing of the intake valve 74 or the closing timing of the exhaust valve 78.

In the first embodiment described above, the variable nozzle 22c and the exhaust throttle valve 24 of the turbocharger 22 correspond to the “back pressure variable means” in the first invention. Further, when the ECU 60 executes the processing of step 106, the “starting overlap period setting means” and the “starting back pressure control means” in the first invention execute the processing of step 104. Thus, the “start completion point determination means” in the first invention realizes the “post-startup overlap period setting means” in the first invention by executing the processing of step 108.
Further, the “starting boost pressure control means” according to the second aspect of the present invention is realized by the ECU 60 executing the processing of step 108.
Further, the “starting nozzle opening control means” in the third aspect of the present invention is realized by the ECU 60 executing the processing of step 108.
Further, the “starting nozzle opening control means” according to the fourth aspect of the present invention is implemented by the ECU 60 executing the process 106.
Further, the ECU 60 executes the processing of step 108, thereby realizing the “post-start throttle valve opening setting means” in the fifth aspect of the invention.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure which shows the cross section of one cylinder of the diesel engine in the system shown in FIG. It is a figure showing the mode of change of the engine speed at the time of starting of a diesel engine. It is the figure which each represented the in-cylinder temperature of a diesel engine, and the new air quantity in relation to the residual gas quantity (internal EGR gas quantity). In Embodiment 1 of this invention, it is a time chart for demonstrating the characteristic control performed when starting a diesel engine at the time of cold. It is a flowchart of the routine performed in Embodiment 1 of the present invention.

Explanation of symbols

10 Diesel engine 18 Exhaust manifold 20 Exhaust passage 22 Variable nozzle turbocharger (VNT)
22a Turbine 22b Compressor 22c Variable nozzle (VN)
24 Exhaust throttle valve 26 Intake passage 32 Intake manifold 46 Water temperature sensor 60 ECU (Electronic Control Unit)
72 Crank angle sensor 74 Intake valve 76 Intake variable valve mechanism 78 Exhaust valve 80 Exhaust variable valve mechanism

Claims (6)

A variable valve mechanism for varying a valve overlap period in which an intake valve opening period and an exhaust valve opening period overlap;
Back pressure variable means for changing the back pressure of the internal combustion engine;
A starting overlap period setting means for controlling the variable valve mechanism to set the valve overlap period during the start of the internal combustion engine;
A starting back pressure control means for increasing back pressure using the back pressure variable means during the start;
Start completion time determination means for determining the start completion time of the internal combustion engine;
A post-startup overlap period setting means for setting the valve overlap period in a shorter period than before reaching the start completion time after reaching the start completion time;
A control device for an internal combustion engine, comprising: A supercharger capable of supercharging an internal combustion engine;
A post-startup supercharging pressure control means for increasing the supercharging pressure of the internal combustion engine by using the supercharger after reaching the start completion time, compared with before reaching the start completion time;
The control apparatus for an internal combustion engine according to claim 1, further comprising: The turbocharger is a turbocharger having a variable nozzle for adjusting the flow rate of exhaust gas supplied to a turbine,
3. The internal combustion engine according to claim 2, wherein the post-startup supercharging pressure control means includes a post-startup nozzle opening control means that controls at least the opening degree of the variable nozzle after reaching the start completion time point. Engine control device. The back pressure variable means is the variable nozzle,
4. The control apparatus for an internal combustion engine according to claim 3, wherein the starting back pressure control means includes a starting nozzle opening control means for controlling the opening of the variable nozzle to be small during the starting. The supercharger is a turbocharger,
The back pressure variable means is disposed in an exhaust passage downstream of the turbine of the turbocharger, and includes an exhaust throttle valve that adjusts an exhaust gas flow rate,
The starting back pressure control means is means for increasing back pressure by performing at least control for closing the exhaust throttle valve during the starting,
The post-startup supercharging pressure control means sets the opening of the exhaust throttle valve to an opening on the opening side as compared with before reaching the start completion time after reaching the start completion time. The control device for an internal combustion engine according to any one of claims 2 to 4, further comprising valve opening setting means.   The after-start overlap period setting means controls at least one of the opening timing of the intake valve and the closing timing of the exhaust valve so that the opening timing of the intake valve is a timing after exhaust top dead center, and the exhaust valve 6. The valve overlap period after reaching the start completion time is set by creating a state in which the closing timing of the engine is later than the opening timing of the intake valve. The control device for an internal combustion engine according to any one of the preceding claims.

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