JP2018031279A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable combustion of an air-fuel mixture without lowering temperature in a cylinder.SOLUTION: An engine (1) comprises a plurality of intake valves (18), a plurality of exhaust valves (19), a variable valve gear (25, 26) capable of changing the valve characteristics of the plurality of intake valves and the plurality of exhaust valves, and an exhaust gas recirculation device (27) for returning exhaust gas to the intake side. An ECU (32) controls the variable valve gear such that in an intake stroke, when returning the exhaust gas to the intake side by the exhaust gas recirculation device, the lift of at least one intake valve (18a) among the plurality of intake valves is increased larger than that of the other intake valves (18b) and, among the plurality of exhaust valves, the lift of the other exhaust valve (19b) different from one exhaust valve (19a) situated on the downstream side of one intake valve is increased larger than that of the one exhaust valve.SELECTED DRAWING: Figure 2

Description

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

  In recent engines, for the purpose of further improving fuel consumption, a gasoline engine of a premixed compression ignition (HCCI) type has been studied (for example, see Patent Document 1). In the premixed pressure ignition type engine, for example, internal EGR (Exhaust Gas Recirculation) is used to promote self-ignition of the air-fuel mixture by increasing the temperature in the cylinder after compression.

  In the engine described in Patent Document 1, a swirl flow is generated when fresh air is introduced into a cylinder. As a result, a fresh air layer is formed along the cylinder wall surface, while an internal EGR gas layer is formed at the center of the cylinder.

JP 2001-164997 A

  However, in patent document 1, the temperature of a cylinder wall surface falls because fresh air exists in the vicinity of a cylinder wall surface. As a result, the air-fuel mixture does not reach the temperature required for self-ignition, and there is a risk that the stability of combustion may not be ensured.

  The present invention has been made in view of this point, and an object of the present invention is to provide a control device for an internal combustion engine that can stably burn an air-fuel mixture without lowering the temperature in the cylinder.

  An internal combustion engine control apparatus according to the present invention includes a plurality of intake valves and a plurality of exhaust valves, a variable valve mechanism capable of changing valve characteristics of the plurality of intake valves and the plurality of exhaust valves, and exhaust gas to the intake side. And an exhaust gas recirculation device that returns the exhaust gas to the intake side during the intake stroke when the exhaust gas is returned to the intake side by the exhaust gas recirculation device. The lift amount of the other exhaust valve is different from the one exhaust valve located downstream of the one intake valve among the plurality of exhaust valves. The variable valve mechanism is controlled to be larger than the valve.

  According to this configuration, when the exhaust gas is returned to the intake side by the exhaust gas recirculation device during the intake stroke, the valve characteristics are changed so that the lift amount of one intake valve and the other exhaust valve is increased, thereby Inside, a swirl flow of exhaust gas from one intake valve to another exhaust valve is generated. Thereby, exhaust gas can be distributed along a cylinder wall surface. The exhaust gas can suppress the approach of the air-fuel mixture that contributes to combustion to the cylinder wall surface, and can suppress the occurrence of cooling loss of the combusted air-fuel mixture. Further, since fresh air can be introduced into the center of the cylinder, combustion of the air-fuel mixture can be promoted at the center of the cylinder. Thus, the air-fuel mixture can be stably burned without lowering the temperature in the cylinder.

  In the control device for an internal combustion engine according to the present invention, it is preferable that the other exhaust valve is provided at a position facing the one intake valve with a center of a cylinder interposed therebetween. According to this configuration, by providing another exhaust valve at a position away from one intake valve, it is easy to generate a swirl flow of exhaust gas along the cylinder wall surface from one intake valve toward the other exhaust valve. can do.

  In the control device for an internal combustion engine according to the present invention, the exhaust gas recirculation device includes an exhaust gas inlet port connected to an exhaust port and an exhaust gas outlet port connected to the intake port, and the exhaust gas The discharge port is preferably connected to the intake port on the one intake valve side. According to this configuration, the exhaust gas discharge port is provided on the side of one intake valve in which the lift amount is greatly changed, so that the exhaust gas can be easily taken into the cylinder from one intake valve.

  In the control device for an internal combustion engine according to the present invention, the internal combustion engine further includes an on-off valve that opens and closes the intake port upstream of the exhaust gas discharge port, and the on-off valve supplies exhaust gas to the intake side. It is preferable that it is closed when it is returned to. According to this configuration, when the exhaust gas is returned to the intake side, the on-off valve is closed, so that the exhaust gas returned to the intake side and fresh air are prevented from being mixed before being introduced into the cylinder. can do. Therefore, the exhaust gas can be easily taken into the cylinder.

  In the control device for an internal combustion engine according to the present invention, it is preferable that the other exhaust valve is opened during an intake stroke when the exhaust gas is returned to the intake side. According to this configuration, the other exhaust valve is opened during the intake stroke, so that a part of the exhaust gas discharged from the other exhaust valve in the previous exhaust stroke can be reintroduced into the cylinder. As a result, the exhaust gas can be easily distributed along the cylinder wall surface.

  In the control device for an internal combustion engine according to the present invention, it is preferable that the other exhaust valve is closed at a later timing than the one exhaust valve during the intake stroke when the exhaust gas is returned to the intake side. . According to this configuration, since the closing timing of one exhaust valve and the other exhaust valve is different, the flow rate of the exhaust gas reintroduced from one exhaust valve and the exhaust gas reintroduced from the other exhaust valve are reduced. A difference in flow rate can be provided. Therefore, a swirl flow is generated in the exhaust gas reintroduced from the exhaust valve, and the exhaust gas can be distributed over a wide range along the cylinder wall surface.

  In the control device for an internal combustion engine according to the present invention, it is preferable that the one intake valve is opened during an exhaust stroke when exhaust gas is returned to the intake side. According to this configuration, the exhaust gas is introduced into the intake port from the one intake valve during the exhaust stroke, and the exhaust gas introduced into the intake port during the subsequent intake stroke is combined with the exhaust gas returned from the exhaust gas discharge port in the cylinder. Therefore, it is possible to easily generate a swirl flow in the cylinder.

  In the control device for an internal combustion engine according to the present invention, it is preferable that the one intake valve is opened earlier than the other intake valves during the exhaust stroke when the exhaust gas is returned to the intake side. . According to this configuration, since the closing timing of one intake valve and the other intake valve is different, the exhaust gas from the exhaust gas discharge port can be first introduced along the cylinder wall surface from one intake valve. it can. Thereafter, fresh air can be introduced from the other intake valves toward the center of the cylinder.

  According to the present invention, by generating a swirl flow in the exhaust gas introduced from the exhaust gas recirculation device, the air-fuel mixture can be stably burned without lowering the temperature in the cylinder.

It is a conceptual diagram of the engine which concerns on this Embodiment. FIG. 3 is a schematic plan view around one cylinder in the multi-cylinder engine according to the present embodiment. It is a graph which shows the opening / closing timing of the intake valve and exhaust valve which concern on this Embodiment. It is a plane schematic diagram which shows the distribution of the exhaust gas and fresh air in the cylinder which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, an example in which the internal combustion engine (engine) and the control device (ECU) for the internal combustion engine according to the present invention are applied to a four-wheeled vehicle will be described. It is. For example, the internal combustion engine and the control device for the internal combustion engine according to the present invention may be applied to other types of vehicles (for example, motorcycles). In the following drawings, a part of the configuration is omitted for convenience of explanation.

  With reference to FIG.1 and FIG.2, schematic structure of the engine which concerns on this Embodiment is demonstrated. FIG. 1 is a conceptual diagram of an engine according to the present embodiment. FIG. 2 is a schematic plan view of the periphery of one cylinder in the multi-cylinder engine according to the present embodiment. In the present embodiment, it is assumed that the configuration normally provided in the automobile is provided, and the description thereof is omitted. In FIG. 2, the left side of the paper is the intake side, the right side of the paper is the exhaust side, the upper side of the paper is one side, and the lower side is the other side.

  The engine 1 as the internal combustion engine according to the present embodiment compresses the air-fuel mixture in which air and fuel are mixed in advance without using the spark ignition (SI: Spark Ignition) of the air-fuel mixture by the ignition device 17 and the ignition device 17. It is configured to be able to switch between premixed compression ignition (HCCI) for self-ignition. The engine 1 is, for example, an in-line multi-cylinder gasoline engine.

  As shown in FIG. 1, the engine 1 is a direct acting DOHC (Double OverHead Camshaft) engine. The engine 1 includes a crankshaft 10, a cylinder 11, a cylinder head 12, and the like in a crankcase (not shown). A piston 13 is accommodated in the cylinder 11 so as to reciprocate up and down. The crankshaft 10 and the piston 13 are connected by a connecting rod 14. In the engine 1, the crankshaft 10 is rotated via the connecting rod 14 as the piston 13 reciprocates in the vertical direction.

  The internal space of the cylinder head 12 constitutes a combustion chamber 15. The cylinder head 12 is provided with a fuel injection device 16 that directly injects fuel into each cylinder and an ignition device 17 that ignites the air-fuel mixture. The fuel injection device 16 injects fuel into the combustion chamber 15 in accordance with a command from the ECU 32 described later. The ignition device 17 is provided above the combustion chamber 15. The ignition device 17 generates a spark at a predetermined timing according to a command from the ECU 32. Thereby, the air-fuel mixture in the combustion chamber 15 is ignited.

  The cylinder head 12 is provided with an intake valve 18 and an exhaust valve 19. In particular, as shown in FIG. 2, the cylinder head 12 is provided with a plurality of intake valves 18a and 18b and a plurality of exhaust valves 19a and 19b for each cylinder (in this embodiment, intake and exhaust respectively. 4 in total, 2 each). An intake port 20 and an exhaust port 21 provided for each cylinder are branched into a plurality of portions corresponding to the intake valves 18 and the exhaust valves 19 (intake ports 20a and 20b and exhaust ports 21a and 21b). In addition to the intake valve 18a, the intake port 20a is provided with an on-off valve 22 that opens and closes the intake port 20a. The on-off valve 22 is provided on the upstream side of an exhaust gas discharge port 30 described later.

  An intake camshaft 23 and an exhaust camshaft 24 are provided above the intake valve 18 and the exhaust valve 19. A cam chain (not shown) is bridged around the crankshaft 10, the intake camshaft 23, and the exhaust camshaft 24. The rotation of the crankshaft 10 is transmitted to the intake camshaft 23 and the exhaust camshaft 24 via the cam chain. The intake valve 18 and the exhaust valve 19 are reciprocated toward the combustion chamber 15 by rotating the intake camshaft 23 and the exhaust camshaft 24. In this way, opening and closing of the intake valve 18 and the exhaust valve 19 are controlled.

  The engine 1 is also provided with an intake variable valve mechanism 25 that can change the valve characteristics of the intake valve 18 and an exhaust variable valve mechanism 26 that can change the valve characteristics of the exhaust valve 19. As will be described in detail later, the intake variable valve mechanism 25 and the exhaust variable valve mechanism 26 independently change the opening / closing timings and lift amounts of the intake valve 18 and the exhaust valve 19 in accordance with commands from the ECU 32.

  Further, the engine 1 is provided with an exhaust gas recirculation device 27 as an external EGR system (Exhaust Gas Recirculation system) for returning a part of the exhaust gas to the intake side and reburning it. Specifically, the exhaust gas recirculation device 27 has a bypass path 28 that forms an exhaust gas recirculation path. The bypass path 28 is arranged to be biased to one side (the intake valve 18a and the exhaust valve 19a side) in the direction in which the two intake valves 18 and the exhaust valve 19 are adjacent to each other.

  The upstream end of the bypass path 28 constitutes an exhaust gas inlet 29 connected to the exhaust port 21. The exhaust gas suction port 29 is provided on the one exhaust port 21a side. The downstream end of the bypass path 28 constitutes an exhaust gas discharge port 30 connected to the intake port 20. The exhaust gas discharge port 30 is provided on one intake port 20 side. Further, an EGR valve 31 that adjusts the intake amount of exhaust gas is provided in the middle of the bypass passage 28.

  In the exhaust gas recirculation device 27, a part of the exhaust gas after combustion discharged from the cylinder 11 is led to the intake port 20 via the bypass path 28 during intake and is recirculated into the cylinder 11. Thereby, nitrogen oxides in the exhaust gas can be reduced and fuel consumption can be improved.

  Various operations in the engine 1 are comprehensively controlled by the ECU 32. The ECU 32 includes a processor that executes various processes in the engine 1, a memory, and the like. The memory is configured by a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) according to the application. The memory stores a control program for controlling each part of the engine 1. The ECU 32 performs drive control of the intake variable valve mechanism 25 and exhaust variable valve mechanism 26, operation control of the fuel injection device 16 and ignition device 17, and open / close control of the open / close valve 22 and the EGR valve 31.

  By the way, in the conventional HCCI engine, when introducing fresh air into the cylinder by adjusting the valve characteristics (for example, valve timing) of the intake valve and the exhaust valve, the swirl flow around the central axis of the cylinder, that is, A swirl flow is generated. Thereby, since the air-fuel mixture of fresh air (intake air) and fuel is evenly distributed to the cylinder wall surface 11a, the flame propagation during combustion is uniform and a good combustion state is obtained.

  However, when fresh air close to room temperature comes into contact with the cylinder wall surface 11a, the heat of the cylinder wall surface 11a is taken away by the fresh air (cooling loss), and the temperature of the cylinder wall surface 11a is lowered. As a result, the stability of the combustion of the air-fuel mixture is impaired, and in some cases, it is assumed that good combustion cannot be continued and misfire occurs. As described above, the contact of fresh air with the cylinder wall surface 11a in the intake stroke has been an important issue in the HCCI engine.

  Therefore, in the present embodiment, when introducing the external EGR, the swirl flow is generated in the exhaust gas by adjusting the valve characteristics (valve lift amount) of the specific intake valve 18 and the exhaust valve 19. Specifically, the lift amount of another exhaust valve 19b different from the exhaust valve 19a located on the downstream side of the intake valve 18a is made larger than that of the exhaust valve 19a. Thereby, exhaust gas can be distributed along the cylinder wall surface 11a, and it can suppress that fresh air contacts the cylinder wall surface 11a. The exhaust gas after combustion is hotter than fresh air. For this reason, even if exhaust gas contacts the cylinder wall surface 11a, the temperature fall of the cylinder wall surface 11a can be suppressed.

  In addition, an air-fuel mixture mainly composed of fresh air can be distributed on the center side of the cylinder 11, that is, inside the exhaust gas. For this reason, the air-fuel mixture can be intensively burned at the center of the cylinder 11 and it is possible to prevent a delay in the combustion speed. Thus, the air-fuel mixture can be stably burned without lowering the temperature in the cylinder.

  Next, the valve characteristics of the intake and exhaust valves according to the present embodiment and the flow of intake and exhaust in the engine will be described with reference to FIGS. FIG. 3 is a graph showing the opening / closing timing and lift amount of the intake valve and the exhaust valve according to the present embodiment. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the lift amount. FIG. 4 is a schematic plan view showing the distribution of exhaust gas and fresh air in the cylinder according to the present embodiment.

  First, the valve characteristics (opening / closing timing and lift amount) of the intake valves 18a and 18b and the exhaust valves 19a and 19b at the time from the exhaust stroke to the intake stroke will be described. As shown in FIG. 2 and FIG. 3, in the exhaust stroke, one exhaust valve 19a (exhaust valve 19a on the exhaust recirculation device 27 side: hereinafter simply referred to as exhaust valve 19a) is connected to the other exhaust valve 19b (hereinafter referred to as exhaust valve 19a). The exhaust valve 19b is simply opened first. In the exhaust stroke, the lift amount of the exhaust valve 19b is changed to be larger than the lift amount of the exhaust valve 19a. Further, in the intake stroke, the exhaust valve 19b is closed at a later timing than the exhaust valve 19a.

  Also, one intake valve 18a (intake valve 18a on the exhaust gas recirculation device 27 side, hereinafter simply referred to as the intake valve 18a) is connected to the other intake valve 18b (hereinafter simply referred to as the intake valve 18b) before the exhaust stroke ends. It will be opened before. In the intake stroke, the lift amount of the intake valve 18a is changed to be larger than the lift amount of the intake valve 18b. Further, the intake valve 18a is closed at a later time than the intake valve 18b.

  Thus, in the transition period from the exhaust stroke to the intake stroke, a period (valve overlap period) in which both the exhaust valve 19b and the intake valve 18a are opened with a relatively large lift amount is provided. By providing the valve overlap period, a swirl flow can be generated in the cylinder 11.

  Next, the flow of intake and exhaust in the engine 1 (see FIG. 1) from the exhaust stroke to the intake stroke will be described. As shown in FIG. 2, the EGR valve 31 is opened while the on-off valve 22 is closed. Exhaust gas after combustion is sucked from the exhaust gas inlet 29 and introduced into the intake port 20 from the exhaust gas outlet 30 through the bypass 28. In particular, since the exhaust gas discharge port 30 is provided on the intake valve 18a side, the exhaust gas can be easily taken into the cylinder 11 from the intake valve 18a. At this time, since the on-off valve 22 is closed, fresh air is not introduced into the intake port 20a.

  Before the exhaust stroke when exhaust gas is recirculated by the exhaust gas recirculation device 27 ends, the intake valve 18a is opened as described above. This makes it easy to introduce the exhaust gas (external EGR) returned from the exhaust gas discharge port 30 into the cylinder 11 from the intake valve 18a using the inertia of the exhaust gas discharged from the exhaust valves 19a and 19b during the exhaust stroke. can do.

  In the above case, the intake valve 18a is opened earlier than the intake valve 18b. In this case, since the closing timing of the intake valve 18a and the intake valve 18b is different, the exhaust gas from the exhaust gas discharge port 30 can be introduced from the intake valve 18a first along the cylinder wall surface 11a. Thereafter, fresh air can be introduced from the intake valve 18 b toward the center of the cylinder 11.

  In the intake stroke when exhaust gas is recirculated by the exhaust gas recirculation device 27, the exhaust valve 19b is opened with a high lift amount, and the intake valve 18a is also opened with a high lift amount. As a result, a swirl flow of exhaust gas (external EGR) is generated in the cylinder 11 from the intake valve 18a toward the exhaust valve 19b. As a result, the exhaust gas can be distributed along the cylinder wall surface 11a.

  In particular, in the present embodiment, the exhaust valve 19b changed to a large lift amount is provided at a position facing the intake valve 18a across the center C of the cylinder 11. In this case, since the exhaust valve 19b is provided at a position away from the intake valve 18a, it is possible to easily generate a swirl flow of exhaust gas along the cylinder wall surface 11a from the intake valve 18a toward the exhaust valve 19b.

  Further, by opening the exhaust valve 19b during the intake stroke, part of the exhaust gas discharged from the exhaust valve 19b during the previous exhaust stroke can be reintroduced into the cylinder 11. In this case, the intake valve 18a is opened with a large lift amount. The exhaust valve 19b is closed at a later time than the exhaust valve 19a. Thus, a swirl flow of exhaust gas (internal EGR) can be generated from the exhaust valve 19b toward the intake valve 18a. As a result, the exhaust gas can be easily distributed along the cylinder wall surface 11a. In this way, exhaust gas can be distributed along the cylinder wall surface 11a using not only the external EGR but also the internal EGR.

  The exhaust valve 19b is closed at a later time than the exhaust valve 19a. In this case, the closing timing of the exhaust valve 19a and the exhaust valve 19b is different, so that the flow rate of the exhaust gas reintroduced from the exhaust valve 19a and the flow rate of the exhaust gas reintroduced from the exhaust valve 19b are made different. Can do. That is, the flow rate of the exhaust gas reintroduced from the exhaust valve 19b is larger than the flow rate of the exhaust gas reintroduced from the exhaust valve 19a. As a result, a swirl flow is generated in the exhaust gas (internal EGR) reintroduced into the cylinder 11, and the exhaust gas can be distributed over a wide range along the cylinder wall surface 11a.

  Further, by opening the intake valve 18b during the intake stroke, fresh air can be introduced into the cylinder 11 through the intake port 20b. As described above, since exhaust gas is distributed on the cylinder wall surface 11 a, fresh air is introduced into the center of the cylinder 11. In particular, the on-off valve 22 is closed while the exhaust gas is returned to the intake side. For this reason, it is possible to prevent the exhaust gas (external EGR) returned to the intake side and fresh air from being mixed before being introduced into the cylinder 11. Therefore, it is possible to easily take the exhaust gas into the cylinder.

  As a result of introducing the exhaust gas and the fresh air into the cylinder 11 in this way, a cylindrical exhaust gas layer G is formed along the cylinder wall surface 11a in the cylinder 11 as shown in FIG. Further, the air-fuel mixture M mainly composed of fresh air can be distributed inside the exhaust gas layer G, that is, in the center of the cylinder 11. The exhaust gas layer G can suppress the approach of fresh air (mixed gas M) contributing to combustion to the cylinder wall surface, and can suppress the occurrence of cooling loss of the burned mixed gas. Further, since fresh air can be introduced into the center of the cylinder 11, combustion of the air-fuel mixture can be promoted at the center of the cylinder 11.

  In particular, in the present embodiment, it is possible to suppress the combustion speed delay caused by the external EGR by generating a strong swirl flow in the exhaust gas. For example, when there is no swirl flow in the exhaust gas, the exhaust gas is unevenly distributed in the cylinder 11. In this case, since it is difficult to burn in a place where there is a lot of exhaust gas, the combustion speed becomes uneven. As a result, the combustion speed of the air-fuel mixture in the cylinder 11 decreases.

  On the other hand, in the present embodiment, the exhaust gas is distributed along the cylinder wall surface 11 a and the stratification is performed, whereby the air-fuel mixture mainly including fresh air can be distributed in the center of the cylinder 11. As a result, it is possible to prevent the combustion rate of the air-fuel mixture from decreasing. Moreover, since the internal pressure of the cylinder 11 increases as the combustion speed of the air-fuel mixture increases, the engine output can be easily obtained, and the fuel consumption can be improved.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above-described embodiment, the premixed compression ignition type engine 1 has been described as an example, but the present invention is not limited to this configuration. The engine 1 may be a spark ignition engine or a diesel engine.

  In the above-described embodiment, two intake valves 18 and two exhaust valves 19 are provided for each cylinder. However, the present invention is not limited to this configuration. Three or more intake valves 18 and three exhaust valves 19 may be provided.

  As described above, the present invention has an effect that the air-fuel mixture can be stably burned without lowering the temperature in the cylinder, and is particularly useful for a control device for an internal combustion engine.

1 engine (internal combustion engine)
11 Cylinder 11a Cylinder wall 18 Intake valve 18a One intake valve (one intake valve)
18b The other intake valve (other intake valve)
19 Exhaust valve 19a One exhaust valve (one exhaust valve)
19b The other exhaust valve (other exhaust valve)
20 Intake port 21 Exhaust port 22 On-off valve 25 Intake variable valve mechanism (variable valve mechanism)
26 Exhaust variable valve mechanism (variable valve mechanism)
27 Exhaust gas recirculation device 28 Bypass path 29 Exhaust gas suction port 30 Exhaust gas discharge port 32 ECU (control device)
C Center of cylinder

Claims (8)

A plurality of intake valves and a plurality of exhaust valves;
A variable valve mechanism capable of changing valve characteristics of the plurality of intake valves and the plurality of exhaust valves;
An internal combustion engine control device comprising an exhaust gas recirculation device for returning exhaust gas to the intake side,
In the intake stroke, when the exhaust gas is returned to the intake side by the exhaust gas recirculation device, the lift amount of at least one intake valve of the plurality of intake valves is made larger than the other intake valves, and the exhaust valves of the plurality of exhaust valves are Of these, the variable valve mechanism is controlled so that the lift amount of another exhaust valve different from one exhaust valve located downstream of the one intake valve is larger than that of the one exhaust valve. A control device for an internal combustion engine.   2. The control device for an internal combustion engine according to claim 1, wherein the other exhaust valve is provided at a position facing the one intake valve across a center of a cylinder. The exhaust gas recirculation device has an exhaust gas inlet connected to the exhaust port, and an exhaust gas outlet connected to the intake port,
The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the exhaust gas discharge port is connected to the intake port on the one intake valve side. The internal combustion engine further includes an on-off valve that opens and closes the intake port upstream of the exhaust gas discharge port,
The control device for an internal combustion engine according to claim 3, wherein the on-off valve is closed when exhaust gas is returned to the intake side.   The control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the other exhaust valve is opened during an intake stroke when the exhaust gas is returned to the intake side.   6. The control apparatus for an internal combustion engine according to claim 5, wherein the other exhaust valve is closed at a later timing than the one exhaust valve during an intake stroke when the exhaust gas is returned to the intake side.   The control apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the one intake valve is opened during an exhaust stroke when the exhaust gas is returned to the intake side.   8. The control apparatus for an internal combustion engine according to claim 7, wherein the one intake valve is opened earlier than the other intake valve during an exhaust stroke when exhaust gas is returned to the intake side.

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