JP4930396B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus suitable as an apparatus for controlling an internal combustion engine having an exhaust throttle valve in an exhaust passage downstream of an exhaust purification catalyst.

  Conventionally, for example, Patent Document 1 discloses an intake control device for an engine that includes an intake throttle valve in an intake passage and an exhaust throttle valve in an exhaust passage. More specifically, in this conventional control device, when the exhaust gas flow rate is restricted by the exhaust throttle valve, the intake amount restriction region by the intake throttle valve is expanded compared to when the exhaust gas flow rate is not restricted. I am doing so.

Japanese Patent Laid-Open No. 6-108884 JP 2001-355462 A

  When the exhaust gas flow rate is limited by the exhaust throttle valve during the cold time as in the conventional control device described above, the exhaust gas temperature is likely to rise, and as a result, the exhaust purification catalyst that is not yet in an active state can be obtained. It becomes possible to promote warm-up. However, there is a time delay from when the exhaust gas flow rate is limited until the exhaust pressure at which the catalyst warm-up effect is expected is reached. In the conventional technique, the exhaust emission cannot be reduced during a period in which such a time delay is recognized. For this reason, the conventional technique does not reduce exhaust emission by promoting warm-up of the exhaust purification catalyst. In order to obtain the emission reduction effect of emissions (particularly HC), there was still room for improvement.

  The present invention has been made in order to solve the above-described problems. In an internal combustion engine that restricts the flow rate of exhaust gas by an exhaust throttle valve during start-up when the exhaust purification catalyst is in an inactive state, It is an object of the present invention to provide a control device for an internal combustion engine that can reduce exhaust emissions without impairing the warm-up effect of the purification catalyst.

A first invention is a control device for an internal combustion engine,
An exhaust throttle valve disposed in the exhaust passage downstream of the exhaust purification catalyst;
An exhaust variable valve mechanism that makes it possible to change the closing timing of the exhaust valve;
Exhaust gas flow rate limiting means for limiting the flow rate of exhaust gas by the exhaust throttle valve when starting the internal combustion engine in a state where the exhaust purification catalyst is determined to be in an inactive state;
Based on the temperature of the exhaust gas purification catalyst during the execution period of the flow rate restriction and the exhaust pressure during the execution period, the early closing control for making the closing timing of the exhaust valve earlier than the exhaust top dead center during the execution period Exhaust valve early closing necessity determination means for determining whether or not to perform,
An exhaust valve early closing execution means for executing the early closing control when the exhaust valve early closing necessity determination means determines that the early closing control should be performed;
It is characterized by providing.

The second invention is the first invention, wherein
The exhaust valve early closing necessity judging means judges that the early closing control should be performed in an initial stage of starting the flow restriction.

The third invention is the first invention, wherein
The exhaust valve early closing necessity determining means determines whether the exhaust pressure early closing is determined to have reached an exhaust pressure at which the warming-up effect of the exhaust purification catalyst accompanying the execution of the flow restriction is expected after the start of the flow restriction. It is characterized by determining that closing control should be performed.

In addition, the fourth aspect of the present invention, Oite to third inventions,
The exhaust valve top dead center closing execution means is further provided for setting the exhaust valve closing timing to the exhaust top dead center when it is determined that the exhaust pressure at which the warm-up effect is expected is reached.

According to a fifth invention, in any one of the first to fourth inventions,
The opening timing of the intake valve is set so that a valve overlap period in which the valve opening period of the exhaust valve overlaps with the valve opening period of the intake valve does not occur during the execution period of the flow restriction. .

  According to the first aspect of the present invention, in the internal combustion engine that restricts the flow rate of the exhaust gas by the exhaust throttle valve at start-up when the exhaust purification catalyst is in an inactive state, the warming-up effect of the exhaust purification catalyst by the flow rate restriction is not hindered. It is possible to reduce exhaust emissions. Further, according to the present invention, when performing the flow rate restriction, the period for performing the early closing control of the exhaust valve can be made appropriate, and the catalyst warm-up effect accompanying the execution of the flow rate restriction can be maximized. Become.

  According to the second aspect of the invention, the early closing control of the exhaust valve is executed in the initial stage of starting the flow restriction. Thereby, in a stage where the exhaust pressure at which sufficient catalyst warm-up effect is expected has not been reached, without lowering the exhaust pressure (that is, without hindering the catalyst warm-up effect associated with execution of the flow rate restriction), It becomes possible to reduce the exhaust emission before the exhaust purification catalyst is activated.

  According to the third aspect of the invention, in a stage where the exhaust pressure at which sufficient catalyst warm-up effect is expected is not reached, the exhaust pressure is not lowered (that is, the catalyst warm-up effect associated with the execution of the flow rate restriction is inhibited). Without this, it is possible to reduce the exhaust emission before the exhaust purification catalyst is activated.

  According to the fourth aspect of the present invention, the catalyst accompanying the execution of the flow rate restriction is performed by reliably exhausting the gas subjected to combustion to the exhaust passage 18 without leaving the combustion chamber 14 while avoiding the backflow of the exhaust gas. The warm-up effect can be fully exploited.

  According to the fifth aspect of the invention, the catalyst warm-up effect is reduced by preventing the exhaust gas from being blown back from the exhaust passage side to the intake passage side through the combustion chamber during the flow rate restriction execution period. Thus, the catalyst warm-up effect can be sufficiently brought out.

Embodiment 1 FIG.
[System configuration]
FIG. 1 is a diagram for explaining a configuration of an internal combustion engine 10 according to a first embodiment of the present invention. The system of this embodiment includes an internal combustion engine 10. A piston 12 is provided in the cylinder of the internal combustion engine 10. A combustion chamber 14 is formed in the cylinder of the internal combustion engine 10 on the top side of the piston 12. An intake passage 16 and an exhaust passage 18 communicate with the combustion chamber 14.

  An air flow meter 20 that outputs a signal corresponding to the flow rate of air sucked into the intake passage 16 is provided in the vicinity of the inlet of the intake passage 16. A throttle valve 22 is provided downstream of the air flow meter 20. The throttle valve 22 is an electronically controlled throttle valve that can control the throttle opening independently of the accelerator opening. In the vicinity of the throttle valve 22, a throttle sensor 24 for detecting the throttle opening is disposed.

  A fuel injection valve 26 for injecting fuel into the intake port of the internal combustion engine 10 is disposed downstream of the throttle valve 22. A spark plug 28 is attached to the cylinder head of the internal combustion engine 10 so as to protrude from the top of the combustion chamber 14 into the combustion chamber 14. The intake port and the exhaust port are respectively provided with an intake valve 30 and an exhaust valve 32 for bringing the combustion chamber 14 and the intake passage 16 or the combustion chamber 14 and the exhaust passage 18 into a conductive state or a cut-off state.

  The system shown in FIG. 1 includes an intake variable valve mechanism 34 that can change the opening timing of the intake valve 30 and an exhaust variable valve mechanism 36 that can change the closing timing of the exhaust valve 32. The specific configurations of these variable valve mechanisms 34 and 36 are not particularly limited. Here, however, the VVT that continuously varies the phase of cams (not shown) that drive the intake valve 30 and the exhaust valve 32, respectively. It shall be a mechanism.

  FIG. 2 is a diagram for explaining a variable range of opening / closing timings of the exhaust valve 32 and the intake valve 30 by the variable valve mechanisms 34 and 36 shown in FIG. According to the variable valve mechanisms 34 and 36 having the VVT mechanism, by adjusting the advance amounts of the exhaust camshaft and the intake camshaft (each not shown) with respect to the crankshaft, the working angle remains fixed, The opening / closing timing of the exhaust valve 32 and the intake valve 30 can be adjusted within a variable range shown in FIG.

  More specifically, in the example of the valve timing shown in FIG. 2, when the opening / closing timing of the exhaust valve 32 is most advanced, the exhaust valve 32 is opened at about 100 ° CA after compression top dead center. Later, it is closed at a predetermined time before exhaust top dead center. Further, when the opening / closing timing of the exhaust valve 32 is most retarded, the exhaust valve 32 is opened at a predetermined time before the expansion bottom dead center, and then a predetermined time after the exhaust top dead center. It will be closed with. As shown in FIG. 2, in this embodiment, the variable range of the opening / closing timing of the intake valve 30 is adjusted so that the intake valve 30 can be opened at the exhaust top dead center.

  In FIG. 1 again, the internal combustion engine 10 includes a crank angle sensor 38 in the vicinity of the crankshaft. The crank angle sensor 38 is a sensor that reverses the Hi output and the Lo output each time the crankshaft rotates by a predetermined rotation angle. According to the output of the crank angle sensor 38, it is possible to detect the rotational position and rotational speed of the crankshaft, and further the engine speed and the like. The internal combustion engine 10 includes an intake cam angle sensor 40 in the vicinity of the intake cam shaft, and an exhaust cam angle sensor 42 in the vicinity of the exhaust cam shaft. These cam angle sensors 40 and 42 are sensors having the same configuration as the crank angle sensor 38. According to the outputs of the cam angle sensors 40 and 42, the rotational positions (advance amounts) of the intake cam shaft and the exhaust cam shaft can be detected.

  In the exhaust passage 18 of the internal combustion engine 10, an upstream catalyst (SC) 44 and a downstream catalyst (UF) 46 are arranged in series as exhaust purification catalysts for purifying exhaust gas. Further, an air-fuel ratio sensor 48 for detecting the exhaust air-fuel ratio at that position is disposed upstream of the upstream catalyst 44. Further, an oxygen sensor 50 that generates a signal corresponding to whether the air-fuel ratio at that position is rich or lean is disposed between the upstream catalyst 44 and the downstream catalyst 46. Further, an exhaust throttle valve 52 for limiting the flow rate of the exhaust gas flowing through the exhaust passage 18 is disposed in the exhaust passage 18 on the downstream side of the downstream catalyst 46.

The system shown in FIG. 1 includes an ECU (Electronic Control Unit) 60. In addition to the various sensors described above, the ECU 60 is connected to an accelerator position sensor 62 for detecting the accelerator opening, a water temperature sensor 64 for detecting the engine coolant temperature, and the various actuators described above. The ECU 60 can control the operating state of the internal combustion engine 10 based on those sensor outputs.
[Characteristics of Embodiment 1]
By the way, in order for the catalysts 44 and 46 to perform the purification function, the temperature of the catalysts 44 and 46 needs to be a predetermined temperature (for example, 350 ° C.). For this reason, at the time of cold start when the catalysts 44 and 46 are in an inactive state, the gas discharged from the cylinder of the internal combustion engine 10 is the catalyst until the catalysts 44 and 46 are activated and perform the purification function. 44 and 46 are discharged into the atmosphere without being purified. Therefore, at the time of cold start, it is necessary to raise the temperature of the catalysts 44 and 46 to the activation temperature as soon as possible. If the exhaust passage 18 is throttled by the exhaust throttle valve 52 described above, the exhaust gas flow rate is limited, so that the exhaust pressure can be increased, thereby increasing the temperature of the exhaust gas. Therefore, if the exhaust throttle valve 52 restricts the flow rate of the exhaust gas at the cold start, the warm-up of the catalysts 44 and 46 can be promoted.

  However, in the initial stage of starting the exhaust gas flow restriction by the exhaust throttle valve 52, the exhaust pressure is close to the atmospheric pressure, and it is expected that the warming-up of the catalysts 44 and 46 is promoted as the exhaust gas temperature rises. I can't. In other words, there is a time delay from when the exhaust gas flow rate is limited by the exhaust throttle valve 52 until the exhaust pressure at which the catalyst warm-up effect is expected is reached. During a period in which such a time delay is recognized, exhaust emission (particularly HC) cannot be reduced.

  Therefore, in this embodiment, when restricting the exhaust gas flow rate by the exhaust throttle valve 52 during start-up when the catalysts 44 and 46 are in an inactive state, the warm-up effect of the catalysts 44 and 46 due to the flow rate restriction is inhibited. In order to reduce exhaust emissions (particularly HC) before the activation of the catalysts 44 and 46, more specifically, the following control is performed. I did it. That is, based on the temperature of the catalysts 44 and 46 and the exhaust pressure during the flow restriction execution period, should the early closing control be performed so that the closing timing of the exhaust valve 32 is earlier than the exhaust top dead center during the execution period? If it is determined whether or not the early closing control should be performed, the early closing control is performed. More specifically, in the initial stage of starting the flow rate restriction, that is, until reaching the exhaust pressure at which the warming-up effect of the catalysts 44 and 46 accompanying the execution of the flow rate restriction is expected, the early stage of the exhaust valve 32 is performed. Closed control was performed.

  Further, in this embodiment, when it is determined that the exhaust pressure at which the warming-up effect of the catalysts 44 and 46 is expected after starting the execution of the flow restriction by the exhaust throttle valve 52, the gas subjected to combustion is burned. In order to ensure that the catalyst warm-up effect accompanying the rise in exhaust pressure can be obtained more quickly and sufficiently by reliably discharging the exhaust gas into the exhaust passage 18 without leaving it in the chamber 14, the exhaust valve 32 is closed at the top. The point is set at a point, and the setting of such closing time is continued during the subsequent execution of the flow restriction.

  Further, in the present embodiment, the intake valve 30 is opened so that a valve overlap period in which the valve opening period of the exhaust valve 32 overlaps the valve opening period of the intake valve 30 does not occur during the flow rate restriction execution period. The time was set.

FIG. 3 is a flowchart of a routine executed by the ECU 60 in the first embodiment in order to realize the above function. The routine shown in FIG. 3 is started when the internal combustion engine 10 is started.
In the routine shown in FIG. 3, first, it is determined whether or not the conditions for limiting the exhaust gas flow rate by the exhaust throttle valve 52 are satisfied (step 100). More specifically, in this step 100, for example, whether or not the above-described flow restriction condition is satisfied based on whether or not the engine coolant temperature at the start is lower than 25 ° C., in other words, the catalyst 44. , 46 is cold and inactive.

  As a result, if the determination in step 100 is not established, that is, if it is determined that the catalysts 44 and 46 are warmed up and in the active state, the exhaust throttle valve 52 is set to fully open (step 102). On the other hand, when the determination in step 100 is satisfied, that is, when it is determined that the catalysts 44 and 46 are cold and in an inactive state, the exhaust throttle valve 52 is closed to a predetermined opening and the exhaust gas is exhausted. Gas flow restriction is started (step 104).

  Next, it is determined whether or not a warm-up condition for the catalysts 44 and 46 is satisfied after the internal combustion engine 10 is started (step 106). Here, whether or not the warming-up condition of the catalysts 44 and 46 is satisfied, in other words, whether the catalysts 44 and 46 are satisfied, is determined based on whether or not the accumulated air amount after starting the internal combustion engine 10 has reached 100 g. It is determined whether or not the situation requires warm-up.

  As a result, if it is determined in step 106 that the catalyst 44, 46 still needs to be warmed up, it is then determined whether the exhaust pressure initial condition is satisfied (step 108). ). Here, based on whether or not the accumulated air amount after starting the internal combustion engine 10 has reached 30 g, whether or not the exhaust gas pressure initial condition is satisfied, that is, the initial stage of execution of the flow rate restriction. For this reason, it is determined whether or not the exhaust pressure at which the warm-up effect of the catalysts 44 and 46 associated with the execution of the flow restriction is expected has been reached.

  As a result, if it is determined in step 108 that the exhaust pressure at which the warming-up effect of the catalysts 44 and 46 is not yet reached has been reached, then the opening / closing timing of the exhaust valve 32 is set to the most advanced angle in the variable range. By controlling to the position, the closing timing of the exhaust valve 32 is sufficiently advanced with respect to the exhaust top dead center (step 110).

  Next, it is determined whether or not the valve overlap period is provided at the current opening and closing timing of the intake and exhaust valves 30 and 32 and the opening timing of the intake valve 30 is the exhaust top dead center (0 TDC). (Step 112). Specifically, here, it is determined whether or not the advance amount of the opening timing of the intake valve 30 is a predetermined value 1 with reference to the most retarded position. The predetermined value 1 is a value corresponding to an angle from the most retarded position of the opening timing of the intake valve 30 to the exhaust top dead center, as shown in FIG.

  As a result, when the determination in step 112 is established, the current settings of the intake and exhaust valves 30 and 32 are maintained, and the process of step 108 is executed again. On the other hand, if the determination in step 112 is not established, the opening timing of the intake valve 30 is set (adjusted) to the exhaust top dead center (0 TDC) (step 114), and the processing of step 108 is executed again. The

  On the other hand, if it is determined in step 108 that the exhaust pressure at which the warming-up effect of the catalysts 44 and 46 is expected is reached, then the backflow of exhaust gas from the exhaust passage 18 to the combustion chamber 14 is prevented. It is determined whether a backflow prevention condition is satisfied (step 116). Here, whether or not the backflow prevention condition is satisfied is determined based on whether or not the closing timing of the exhaust valve 32 is not set to the exhaust top dead center (exhaust valve closing timing ≠ 0 TDC). .

  As a result, if the determination in step 116 is not established, the current setting of the closing timing of the exhaust valve 32 is maintained, and the processing of step 106 is executed again. On the other hand, when the determination in step 116 is established, the closing timing of the exhaust valve 32 is set (adjusted) to the exhaust top dead center (0 TDC), and the process of step 106 is executed again.

According to the routine shown in FIG. 3 described above, when the exhaust gas restricting valve 52 restricts the flow rate of the exhaust gas during start-up when the catalysts 44 and 46 are in an inactive state, the catalyst 44 during the flow rate restriction execution period is used. , 46 based on the temperature and the exhaust pressure, it is determined whether or not the early closing control of the exhaust valve 32 should be performed during the execution period, and the early closing control is performed as necessary. More specifically, according to the above routine, the early closing control is performed at the initial stage when the flow restriction is started, that is, at the exhaust pressure at which the warm-up effect of the catalysts 44 and 46 accompanying the execution of the flow restriction is expected. It will be done in the stage to reach.
According to the technique for reducing the exhaust emission (particularly HC) by increasing the internal EGR gas amount by the early closing control of the exhaust valve 32, the closing timing of the exhaust valve 32 is delayed from the exhaust top dead center. Compared to the control for increasing the internal EGR gas amount, the catalysts 44 and 46 are activated without causing a decrease in exhaust pressure (that is, without hindering the catalyst warm-up effect associated with the execution of the flow restriction). It becomes possible to reduce the exhaust emission at the time before conversion. Further, in the stage where the exhaust pressure at which a sufficient catalyst warm-up effect is expected has not been reached, exhaust emission reduction is actively performed by the early closing control, so that the inside of the catalysts 44 and 46 is completed before the warm-up is completed. Therefore, it is possible to satisfactorily avoid the amount of purification treatment of the catalysts 44 and 46 from catching up after the warm-up is completed.
On the other hand, after the exhaust pressure reaches a value at which a sufficient catalyst warm-up effect is expected during the flow rate restriction execution period, the exhaust gas is surely discharged without performing the early closing control. It is desirable to be able to discharge to 18. According to the above routine, it is determined whether or not the early closing control of the exhaust valve 32 should be performed during the execution period based on the temperature and exhaust pressure of the catalysts 44 and 46 during the execution period of the flow rate restriction. Thus, the period for performing the early closing control can be made appropriate, and the catalyst warm-up effect associated with the execution of the flow rate restriction can be maximized.

  Further, according to the above routine, after the exhaust pressure reaches the value at which the catalyst warm-up effect is expected, the closing timing of the exhaust valve 32 is set to the exhaust top dead center. If the closing timing of the exhaust valve 32 is retarded from the exhaust top dead center under such an exhaust pressure condition, a backflow of exhaust gas from the exhaust passage 18 to the combustion chamber 14 occurs. On the other hand, when the exhaust valve 32 is closed at the exhaust top dead center or earlier than the exhaust top dead center, such back flow can be prevented. Further, if the exhaust valve 32 is closed at the exhaust top dead center, the gas subjected to combustion is reliably discharged into the exhaust passage 18 without remaining in the combustion chamber 14, thereby warming up the catalyst as the exhaust pressure increases. The machine effect can be obtained more quickly and sufficiently. In other words, at the stage after the exhaust pressure reaches the value at which the catalyst warm-up effect is expected, the exhaust valve backflow is set by setting the closing timing of the exhaust valve 32 to the exhaust top dead center as in the routine processing described above. The catalyst warm-up effect associated with the execution of the flow rate restriction can be sufficiently brought out.

  Further, according to the routine, the opening timing of the intake valve 30 is set to the intake top dead center so that the valve overlap period does not occur during the flow rate restriction execution period. In a situation where the exhaust pressure is increased by the flow restriction by the exhaust throttle valve 52, if there is a valve overlap period, the exhaust pressure is higher than the intake pressure (negative pressure). As a result, the exhaust gas is blown back from the exhaust passage 18 side to the intake passage 16 side. As a result, the exhaust pressure cannot be sufficiently increased using the exhaust throttle valve 52, and the catalyst warm-up effect is diminished. On the other hand, according to the processing of the above routine, such a situation can be avoided and the catalyst warm-up effect can be sufficiently brought out.

  By the way, in the first embodiment described above, the catalysts 44 and 46 need to be warmed up by comparing the integrated air amount with predetermined threshold values (100 g and 30 g) during the flow rate restriction execution period. It is determined whether or not the situation is present, and whether or not the exhaust pressure has not reached a value at which the catalyst warm-up effect is expected. However, the method used for determining whether or not the early closing control of the exhaust valve 32 should be performed in the present invention is not limited to such a method. That is, for example, the catalyst temperature and the exhaust pressure may be directly measured.

  Further, in the first embodiment described above, the advance amount of the opening timing of the intake valve 30 is set by the intake variable valve mechanism 34 so that the valve overlap period does not occur during the flow rate restriction execution period. I try to adjust it. However, in the present invention, the setting of the opening timing of the intake valve 30 so that the valve overlap period does not occur is not limited to that realized by adjusting the opening timing by the intake variable valve mechanism 34. That is, in a system that does not include the intake variable valve mechanism 34, the opening timing of the intake valve 30 may be set in advance to a timing after exhaust top dead center.

In the first embodiment described above, the ECU 60 executes the processing of steps 100 and 104, so that the “exhaust gas flow rate limiting means” in the first invention executes the processing of steps 106 and 108. By doing so, the “exhaust valve early closing necessity determining means” in the first invention is realized, and the “exhaust valve early closing executing means” in the first invention is realized by executing the processing of step 110. ing.
In addition, the “exhaust valve top dead center closing execution means” according to the fourth aspect of the present invention is implemented when the ECU 60 executes the processing of steps 108, 116, and 118 described above.

It is a figure for demonstrating the structure of the internal combustion engine of Embodiment 1 of this invention. It is a figure for demonstrating the variable range of the opening / closing timing of the exhaust valve and intake valve by the variable valve mechanism shown in FIG. It is a flowchart of the routine performed in Embodiment 1 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 14 Combustion chamber 16 Intake passage 18 Exhaust passage 30 Intake valve 32 Exhaust valve 34 Intake variable valve mechanism 36 Exhaust variable valve mechanism 44 Upstream catalyst 46 Downstream catalyst 52 Exhaust throttle valve 60 ECU (Electronic Control Unit)

Claims (5)

An exhaust throttle valve disposed in the exhaust passage downstream of the exhaust purification catalyst;
An exhaust variable valve mechanism that makes it possible to change the closing timing of the exhaust valve;
Exhaust gas flow rate limiting means for limiting the flow rate of exhaust gas by the exhaust throttle valve when starting the internal combustion engine in a state where the exhaust purification catalyst is determined to be in an inactive state;
Based on the temperature of the exhaust gas purification catalyst during the execution period of the flow rate restriction and the exhaust pressure during the execution period, the early closing control for making the closing timing of the exhaust valve earlier than the exhaust top dead center during the execution period Exhaust valve early closing necessity determination means for determining whether or not to perform,
An exhaust valve early closing execution means for executing the early closing control when the exhaust valve early closing necessity determination means determines that the early closing control should be performed;
A control device for an internal combustion engine, comprising:   2. The control device for an internal combustion engine according to claim 1, wherein the exhaust valve early closing necessity determination unit determines that the early closing control should be performed in an initial stage of execution of the flow rate restriction. 3.   The exhaust valve early closing necessity determining means determines whether the exhaust pressure early closing is determined to have reached an exhaust pressure at which the warming-up effect of the exhaust purification catalyst accompanying the execution of the flow restriction is expected after the start of the flow restriction. 2. The control apparatus for an internal combustion engine according to claim 1, wherein it is determined that the closing control should be performed. The exhaust valve top dead center closing execution means for setting the exhaust valve closing timing to an exhaust top dead center when it is determined that the exhaust pressure at which the warm-up effect is expected is reached. Item 5. A control device for an internal combustion engine according to Item 3 .   The opening timing of the intake valve is set so that a valve overlap period in which the valve opening period of the exhaust valve overlaps with the valve opening period of the intake valve does not occur during the execution period of the flow restriction. The control device for an internal combustion engine according to any one of claims 1 to 4.

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