JP6756531B2 - Internal combustion engine control method and control device - Google Patents

Description

The present invention relates to the control of an internal combustion engine.

In internal combustion engines for vehicles, especially gasoline internal combustion engines, so-called downsizing turbo internal combustion engines, which improve fuel efficiency by reducing the displacement with a supercharger and achieve both output performance, are becoming mainstream these days. .. In such an internal combustion engine, a technology is known to improve fuel efficiency by improving pump loss and knocking in a high load range by using an EGR device that returns a part of exhaust gas as EGR gas to an intake passage. Has been done. Especially in recent years, the demand for an increase in the EGR rate (ratio of the amount of EGR gas to the amount of fresh air) has increased more and more from the viewpoint of improving fuel efficiency, and in order to obtain a high EGR rate in a wide engine operation range (engine speed / load range). Technology is required.

Here, when shifting from the EGR region to which the EGR gas is supplied to the non-EGR region to which the EGR gas is not supplied, for example, during deceleration, the EGR control valve is controlled to close as the target EGR rate decreases. Since the EGR gas already remaining in the intake system is introduced into the combustion chamber, the combustion stability may be temporarily deteriorated.

Therefore, in Patent Document 1, an airflow control valve is provided so that the concentration of EGR gas introduced into the combustion chamber of each cylinder has a height difference, and combustion of cylinders # 3 and # 4 having a high EGR concentration is stopped during deceleration. , A technique has been proposed in which the deterioration of combustion stability due to the influence of EGR gas is suppressed by continuing the combustion of # 1 and # 2 cylinders having a low EGR concentration.

JP-A-2009-162172

The firing order of the in-line 4-cylinder internal combustion engine is generally # 1, # 3, # 4, # 2 in consideration of vibration suppression. Here, in the technique described in Patent Document 1, two # 1 and # 2 cylinders having a continuous firing order continue combustion, and two # 3 and # 4 cylinders having a continuous firing order stop combustion. As a result, the torque fluctuation during one cycle becomes large, and the drivability deteriorates. Further, since EGR gas is introduced into the # 1 and # 2 cylinders that continue combustion even though the concentration is low, there is a possibility that combustion becomes unstable due to the influence of EGR gas.

The present invention has been made in view of such circumstances, and while surely suppressing the instability of combustion due to the influence of the EGR gas remaining in the intake passage when the EGR decreases when the target EGR rate decreases. The purpose is to continue combustion and to minimize torque fluctuations while stopping the combustion of some cylinders.

A fresh air supply device capable of supplying fresh air containing no EGR gas to one of the cylinder groups having an odd-numbered combustion sequence or an even-numbered cylinder group is provided. The fresh air supply device includes a fresh air supply passage that introduces fresh air into one of the cylinder groups without passing through the EGR introduction port that connects the EGR passage to the intake passage, and fresh air that opens and closes the fresh air supply passage. It has a flow control valve . When the target EGR rate set according to the engine operating state decreases, the EGR control valve is controlled in the closing direction according to the decrease in the target EGR rate. At this time, fresh air is supplied from the fresh air supply passage to the one cylinder group to continue combustion, while combustion is stopped in the other cylinder group.

According to the present invention, when the target EGR rate decreases, such as during deceleration, combustion tends to become unstable if a large amount of EGR gas remains in the intake passage. However, when the EGR decreases. Combustion stability can be ensured by introducing fresh air that does not contain EGR gas into one cylinder group that continues combustion by means of a fresh air supply device.

On the other hand, scavenging by the other cylinder group that stops combustion allows the EGR gas remaining in the intake passage to be quickly discharged, so that combustion stability should be ensured when combustion is resumed thereafter. Can be done.

In addition, since combustion is performed in the odd-numbered or even-numbered cylinder group in the combustion order, the combustion interval is constant and torque fluctuation is minimized even though the cylinders that stop combustion are provided. be able to.

Further, since fresh air containing no EGR gas can be sufficiently supplied to one cylinder group that continues combustion through the fresh air supply device, the torque is reduced by the other cylinder group that stops combustion. You can make up for the minute.

The block diagram which shows the system configuration of the internal combustion engine to which the control method and the control device which concerns on 1st Embodiment of this invention are applied simply, and shows the state which the switching valve is closed. Similarly, a configuration diagram showing a system configuration of the internal combustion engine of the first embodiment simply and showing a state in which the switching valve is open. The flowchart which shows the control flow of the said 1st Embodiment. The timing chart which shows the mode at the time of EGR lowering of the said 1st Example. The block diagram which shows simply the system structure of the internal combustion engine to which the control method and control device which concerns on 2nd Embodiment of this invention are applied.

Hereinafter, the present invention will be described with reference to the illustrated examples. FIG. 1 simply shows the system configuration of an internal combustion engine to which the control device and the control method according to the first embodiment of the present invention are applied.

The internal combustion engine 10 is an in-line 4-cylinder spark-ignition gasoline internal combustion engine, and an intake passage 12 and an exhaust passage 13 are connected to a combustion chamber 11 of each cylinder. The intake passage 12 is connected to the intake port of each cylinder via the four intake branch passages 16 connected to the intake collector 14 having a predetermined volume, and the exhaust passage 13 is the four exhaust branch passages of the exhaust manifold 17. It is connected to the exhaust port of each cylinder via 18.

The internal combustion engine 10 is provided with a turbocharger 20. In this supercharger 20, a turbine 21 provided in the exhaust passage 13 and a compressor 22 provided in the intake passage 12 are provided back to back on one shaft 23 coaxially, and the turbine 21 is provided by exhaust energy. Supercharges by driving the compressor 22 to rotate. The exhaust passage 13 is provided with a bypass passage 24 that bypasses the turbine 21, and the bypass passage 24 is provided with a wastegate valve 25 that adjusts the boost pressure.

Further, the internal combustion engine 10 is provided with an EGR device (external EGR) that returns a part of the exhaust gas as EGR gas to the intake passage 12. This EGR device is provided in the EGR passage 27 that connects the intake passage 12 and the exhaust passage 13, and the EGR ratio, which is the ratio of the EGR gas to the fresh air, by opening and closing the EGR passage 27. An EGR control valve 28 that controls the flow rate of the EGR gas and an EGR cooler 29 that cools the EGR gas flowing in the EGR passage 27 are provided.

Further, this EGR device is a so-called low pressure type EGR device in which the EGR introduction port 30 in which the EGR passage 27 is connected to the intake passage 12 is arranged on the upstream side of the compressor 22. The EGR outlet 31 in which the EGR passage 27 is connected to the exhaust passage 13 is arranged further downstream than the catalyst 32 such as a three-way catalyst provided on the downstream side of the turbine 21.

In the intake passage 12, an electronically controlled throttle valve 33 for adjusting the intake air amount and an intercooler 34 for cooling the intake air are arranged on the downstream side of the turbine 21.

The firing order of the internal combustion engine 10 is # 1, # 3, # 4, # 2. Then, in this embodiment, of the odd-numbered cylinder groups # 1 and # 4 having an odd-numbered combustion order and the even-numbered cylinder groups # 2 and # 3 having an even-numbered combustion order, the odd-numbered cylinder groups # 1 and # 4 are one of the cylinder groups. , A fresh air supply device capable of supplying fresh air containing no EGR gas is provided.

Specifically, this fresh air supply device includes a fresh air supply passage 41 that introduces fresh air into each cylinder of the odd-numbered cylinder groups # 1 and # 4 without passing through the EGR introduction port 30, and this fresh air supply. It is provided with a fresh air flow rate control valve 42 that opens and closes the passage 41. The fresh air supply passage 41 is connected to the intake passage 12 on the upstream side of the EGR introduction port 30 and to the intake collector 14 located on the downstream side of the intercooler 34 on the downstream side. ..

The fresh air supply passage 41 and the intake branch passages 16 of the odd-numbered cylinder groups # 1 and # 4 are connected to the intake collector 14 on one side 14A (right side in FIG. 1), and the other side 14B (left side in FIG. 1). ) Is connected to the intake passage 12 and the intake branch passage 16 of the even-numbered cylinder groups # 2 and # 3, and a switching valve 43 for switching communication / interruption between the one side 14A and the other side 14B is provided in the middle. ing.

As shown in FIG. 1, when the switching valve 43 is closed, the internal space of the intake collector 14 is divided into one side 14A and the other side 14B. Therefore, the fresh air containing no EGR gas supplied from the fresh air supply passage 41 to one side 14A of the intake collector 14 is directly introduced into the odd-numbered cylinder groups # 1 and # 4 via the intake branch passage 16. , These series of routes constitute the fresh air introduction route 44 shown by the broken line in the figure. Further, the intake gas including the EGR gas supplied from the intake passage 12 to which the EGR passage 27 is connected to the other side 14B of the intake collector 14 goes directly to the even cylinder groups # 2 and # 3 via the intake branch passage 16. These series of routes constitute the EGR introduction route 45 shown by the broken line in the figure. That is, when the switching valve 43 is closed, the fresh air introduction path 44 and the EGR introduction path 45 are shut off.

On the other hand, as shown in FIG. 2, when the switching valve 43 is closed, one side 14A and the other side 14B in the intake collector 14 communicate with each other. Therefore, the intake gas including the EGR gas supplied from the intake passage 12 to which the EGR passage 27 is connected to the other side 14B of the intake collector 14 is substantially evenly supplied to all the cylinders via all the intake branch passages 16. To.

Further, the internal combustion engine 10 is provided with a valve timing changing device 51 capable of changing the valve timing of the intake valve (or exhaust valve). The control unit 50 can store and execute various controls, and although not shown, the throttle valve 33, described above, is based on detection signals of various sensors that detect the engine operating state such as a crank angle sensor and an air flow meter. A control signal is output to the actuators of the wastegate valve 25, the fresh air flow control valve 42, the EGR control valve 28, the switching valve 43, and the valve timing changing device 51 to control their operation.

FIG. 3 is a flowchart showing a flow of control executed by the control unit 40. In step S11, the target EGR rate is read. This target EGR rate corresponds to the ratio of the target flow rate of the EGR gas (external EGR) to the intake air amount, and refers to a preset target EGR rate setting map based on the engine speed and the engine load. Set.

In step S12, it is determined whether or not the target EGR rate is in an EGR decrease (transition) state in which the target EGR rate decreases by a predetermined threshold value or more. For example, it is determined whether or not the current target EGR rate is lower than the threshold value with respect to the target EGR rate before a predetermined period. The determination of the EGR lowering state is not limited to this. For example, when the deceleration state is reached during operation in the EGR region, it is determined that the target EGR rate is lowered and the transition state is a transition state from the EGR region to the non-EGR region. Therefore, it may be determined that the EGR is in a lowered state.

If it is determined in step S12 that the EGR is lowered, the control process (steps S13 to S18) at the time of EGR lowering, which is a main part of this embodiment, is executed. First, in step S13, the fuel injection of the even-numbered cylinder groups # 2 and # 3 having an even combustion order is stopped, and the combustion is stopped. In step S14, the throttle valve 33 is controlled in the opening direction. Specifically, the throttle valve 33 is fully opened. As a result, the scavenging of the even cylinder groups # 2 and # 3 that stop combustion is promoted, the EGR gas remaining in the intake passage 12 is quickly discharged to the exhaust passage 13, and the combustion stability at the time of restarting combustion is improved. Can be made to.

In step S15, the switching valve 43 shuts off the fresh air introduction path 44 and the EGR introduction path 45. As a result, only the fresh air containing no EGR gas is introduced into the odd-numbered cylinder groups # 1 and # 4 that continue to burn via the fresh air introduction path 44, and remains in the intake passage 12. The EGR gas is supplied to the even cylinder groups # 2 and # 3 that stop combustion through the EGR introduction path 45.

In step S16, the fresh air flow rate control valve 42 is controlled in the opening direction. Specifically, the fresh air flow rate control valve 42 is controlled in the opening direction so as to compensate for the decrease in torque of the even-numbered cylinder group that stops combustion, and the amount of fresh air introduced into the odd-numbered cylinder groups # 1 and # 4 is controlled. increase.

In step S17, it is determined whether or not the vehicle is in a supercharged state. In the supercharged state, the valve timing changing device 51 increases the valve overlap. As a result, the scavenging of the even-numbered cylinder groups # 2 and # 3 that have stopped combustion is promoted, and the EGR gas remaining in the intake passage 12 is quickly discharged.

Step S19 and step S20 are conditions for ending the control process (steps S13 to S18) in the EGR lowering state. In step S19, it is determined whether or not the actual EGR rate has decreased to less than a predetermined value. The actual EGR rate is estimated based on the engine operating state such as the engine speed and the engine load. When the actual EGR rate is less than a predetermined value, it is determined that the EGR gas remaining in the intake passage 12 is sufficiently reduced and stable combustion can be performed, and the process proceeds to step S21 or later to control the EGR decrease. Execute the termination process. Further, in step S20, it is determined whether or not there is an acceleration request. For example, when the accelerator pedal is depressed by the driver, it is determined that an acceleration request is required. Even when it is determined in step S20 that there is an acceleration request, the process proceeds to step S21 and subsequent steps so that the torque corresponding to the acceleration request can be obtained, and the control termination process when the EGR is lowered is executed.

In step S21, the fuel injection of the even-numbered cylinder groups # 2 and # 3 that have stopped combustion is restarted, and the combustion is restarted. In step S22, the throttle valve 33, which has been fully opened for scavenging, is controlled in the closing direction. That is, the throttle valve 33 is controlled so that the target intake air amount can be obtained. In step S23, the switching valve 43 is opened to communicate the fresh air introduction path 44 and the EGR introduction path 45. As a result, the intake air introduced into the intake collector 14 from the intake passage 12 is supplied to all the cylinders substantially evenly. Then, in step S24, the fresh air flow rate control valve 42 is closed to end this routine.

FIG. 4 is a timing chart at the time of EGR decrease when the control of this embodiment is applied. When the driver reduces the opening degree of the accelerator pedal from the so-called R / L running state with a partial load (see FIG. 4 (A)) and shifts to the deceleration state (time t1), it is shown in FIG. 4 (G). As described above, the target EGR rate decreases to the EGR decrease state, and the above-mentioned control at the time of EGR decrease (steps S13 to S18) is executed. That is, as shown in FIG. 4 (B), the switching valve 43 is closed to shut off the fresh air introduction path 44 and the EGR introduction path 45, and as shown in FIG. 4 (F), the even-numbered cylinder groups # 2 and # 3 Set the fuel cut flag to stop combustion. At this time, as shown in FIG. 4 (E), the throttle valve 33 is fully opened to promote scavenging for the even-numbered cylinder groups # 2 and # 3 that have stopped combustion, so that the throttle valve 33 remains in the EGR introduction path 45. EGR gas can be discharged quickly.

Further, when the EGR is lowered (t1), the fresh air flow rate control valve 42 is controlled in the opening direction to increase the amount of fresh air introduced into the odd-numbered cylinder groups # 1 and # 4 through the fresh air introduction path 44. This makes it possible to compensate for the torque drop of even-numbered cylinder groups # 2 and # 3 where combustion is stopped.

When the target EGR rate decreases, the actual EGR rate temporarily increases with respect to the decrease in the intake air amount due to the influence of the EGR gas remaining in the intake passage 12, and the actual EGR rate increases in FIGS. 4 (H) and 4 (I). As shown by the characteristics of the broken line, the actual EGR rate may exceed the misfire limit and the combustion stability may deteriorate. On the other hand, in the present embodiment, by performing the above control, fresh air containing no EGR gas is introduced into the odd-numbered cylinder groups # 1 and # 4 through the fresh air introduction path 44. As shown by the characteristics of the solid line in 4 (H), the actual EGR rate rapidly decreases from t1 when the EGR decreases, and there is no possibility that the actual EGR rate will increase beyond the misfire limit, so stable combustion is realized. it can.

Further, as shown in FIG. 4 (I), in the even cylinder groups # 2 and # 3, since combustion is stopped, the internal EGR (exhaust gas flowing back from the exhaust port to the combustion chamber) does not increase. As the EGR gas remaining in the fresh air introduction path 44 is discharged by the scavenging air, the actual EGR rate rapidly decreases. Therefore, it is possible to improve the combustion stability when resuming combustion.

Next, a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, duplicated description is omitted, and different parts will be mainly described.

Like the exhaust passage 13, the intake passage 12 is connected to the combustion chamber 11 of each cylinder via the four intake branch passages 16 of the intake manifold 15. The fresh air supply passage 41 is bifurcated on the downstream side of the fresh air flow rate control valve 42, and the branch portion 41A is divided into the intake branch passages 16 of the # 1 cylinder and the # 4 cylinder forming an odd number cylinder group, respectively. You are connected. Therefore, when the fresh air flow rate control valve 42 is opened when the EGR is lowered, the fresh air containing no EGR gas is odd from the fresh air supply passage 41 and its branch portion 41A through the intake branch passages 16 of the # 1 cylinder and the # 4 cylinder. It is introduced into the combustion chamber 11 of the cylinder groups # 1 and # 4.

In this second embodiment, since the switching valve for shutting off the fresh air introduction path and the EGR introduction path is not provided, a part of the intake air containing the EGR gas continues to burn when the EGR is lowered. It may also be supplied to cylinder groups # 1 and # 4. However, since a large amount of fresh air is introduced into the odd-numbered cylinder groups # 1 and # 4 through the fresh air supply passage 41, most of the intake air containing the EGR gas supplied from the intake passage 12 to the intake manifold 15 is mostly. It will be supplied to the even-numbered cylinder groups # 2 and # 3 that have stopped combustion, and the amount of EGR gas supplied to the odd-numbered cylinder groups # 1 and # 4 will be small.

Next, the characteristic configurations and actions and effects of the above-mentioned first and second examples are listed below.

[1] An EGR passage 27 that connects an even number of cylinders, an exhaust passage 13 and an intake passage 12, and returns EGR gas that is a part of exhaust gas to the intake passage 12, and an EGR that opens and closes the EGR passage 27. A control valve 28 and a fresh air supply device capable of supplying fresh air containing no EGR gas to one of the cylinder groups having an odd-order combustion sequence or an even-order cylinder group are provided. When the target EGR rate set according to the engine operating state decreases, the EGR control valve 28 is controlled in the closing direction according to the decrease in the target EGR rate. At this time, fresh air is supplied from the fresh air supply device to the one cylinder group to continue combustion, while combustion is stopped in the other cylinder group.

For example, when decelerating from the supercharging state, a large amount of EGR gas remains in the intake passage 12 during the transition period (when the EGR decreases) when the target EGR rate decreases and the EGR region shifts to the non-EGR region. In addition, combustion tends to be unstable, but when the EGR drops, combustion stability can be improved by introducing fresh air that does not contain EGR gas to one of the cylinder groups that continues to burn with a fresh air supply device. Can be secured.

On the other hand, the EGR gas remaining in the intake passage 12 can be quickly discharged by scavenging by the other cylinder group that stops combustion. Therefore, the combustion stability after the resumption of combustion can be reliably ensured.

In addition, since combustion is performed in either the odd-numbered or even-numbered cylinder group in the combustion order, the combustion interval is constant and the torque fluctuation is minimized even though the cylinders that stop combustion are provided. It can be suppressed to the limit.

Furthermore, in order to compensate for the torque drop caused by the cylinder group that stops combustion, the cylinder group that continues combustion requires approximately twice the amount of air, but fresh air is introduced via the fresh air supply passage 41. Therefore, it is possible to secure a sufficient amount of fresh air. Moreover, by increasing the amount of fresh air in this way, the internal EGR is reduced, and the external EGR rate can be set higher by that amount, so that the fuel efficiency performance can be further improved.

[2] The fresh air supply device introduces fresh air into one cylinder group without passing through the EGR introduction port 30 in which the EGR passage 27 connects to the intake passage 12, for example, as in the above embodiment. It has a supply passage 41 and a fresh air flow rate control valve 42 that opens and closes the fresh air supply passage 41. In this way, by providing the fresh air supply passage 41, which is a passage different from the original intake passage 12, the cylinder group that continues combustion when the EGR is lowered does not contain EGR gas through the fresh air supply passage 41. It can supply enough fresh air.

[3] Specifically, by controlling the fresh air flow rate control valve 42 in the opening direction when the EGR is lowered, fresh air that does not contain EGR gas is sufficiently provided to the cylinder group that continues combustion only when the EGR is lowered. Can be supplied to.

[4] A supercharger 20 provided in the intake passage 12 on the downstream side of the EGR introduction port 30 and provided with a compressor 22 for supercharging the intake air, and an intake passage 12 on the downstream side of the compressor 22. In the case of a configuration including an electronically controlled throttle valve 33 that opens and closes the intake passage 12, when the EGR is lowered, the throttle valve 33 is controlled in the opening direction.

In this way, by controlling the throttle valve 33 in the direction of opening when the EGR is lowered, scavenging in the cylinder group that stops combustion is promoted, and the EGR gas remaining in the intake passage 12 is quickly discharged, and then the EGR gas remains. Combustion stability can be ensured when combustion is restarted.

In order to obtain the EGR gas discharge effect due to such scavenging, the piston stroke motion stop and the intake / exhaust valve stop are not performed even for the cylinder group that stops combustion.

[5] When the EGR rate drops below a predetermined value when the EGR drops, it is determined that the EGR gas remaining in the intake passage 12 has been sufficiently discharged, and the control is switched to the normal control. That is, the combustion of the cylinder group that has stopped combustion is restarted, the throttle valve 33 is controlled in the closing direction, and the fresh air flow rate control valve 42 is controlled in the closing direction.

[6] Alternatively, even if an acceleration request is detected when the EGR is lowered, the normal operation is switched so that the torque corresponding to the acceleration request can be obtained. That is, the combustion of the cylinder group that has stopped combustion is restarted, the opening degree of the throttle valve 33 is controlled in response to the acceleration request, the wastegate valve 25 is controlled in the closing direction, and the fresh air flow rate control valve is used. The 42 is controlled in the closing direction.

[7] In the first embodiment, the fresh air introduction path 44 for introducing fresh air into one cylinder group via the fresh air supply passage 41 and the intake passage 12 on the downstream side of the EGR passage 27 are used. It has a switching valve 43 for switching communication / shutoff with an EGR introduction path 45 for introducing EGR gas into the other cylinder group. When the EGR is lowered, the switching valve 43 shuts off the fresh air introduction path 44 and the EGR introduction path 45.

By shutting off by the switching valve 43, it is possible to more reliably suppress EGR gas from being mixed into the fresh air introduction path 44, and further improve the combustion stability of the cylinder group that continues combustion.

[8] In the case of a configuration including a valve timing changing device 51 capable of changing the valve timing of the intake valve or the exhaust valve, the valve timing changing device 51 increases the valve overlap when the EGR is lowered, especially in the supercharging state. To control. As a result, scavenging of the cylinder that stops combustion can be promoted, and the EGR gas remaining in the intake passage 12 can be discharged more quickly.

As described above, the present invention has been described based on specific examples, but the present invention is not limited to the above examples, and includes various modifications and modifications. For example, a valve timing changing device capable of changing the valve timing of the exhaust valve may be used. Further, the present invention can be similarly applied not only to an in-line 4-cylinder type internal combustion engine but also to an internal combustion engine of another number and type such as a V-type 6-cylinder engine and a V-type 8-cylinder engine.

Further, a check valve may be provided in the fresh air supply passage 41 to reliably prevent backflow in the direction from the combustion chamber 11 side toward the intake passage 12.

Further, contrary to the above embodiment, the combustion may be stopped in the even-numbered cylinder group having an even-numbered combustion order and continued in the odd-numbered cylinder group having an odd-numbered combustion order.

10 ... Internal combustion engine 11 ... Combustion chamber 12 ... Intake passage 13 ... Exhaust passage 14 ... Intake collector 20 ... Supercharger 22 ... Compressor 25 ... Wastegate valve 27 ... EGR passage (EGR device)
28 ... EGR control valve (EGR device)
30 ... EGR introduction port 33 ... Throttle valve 41 ... Fresh air supply passage (fresh air supply device)
42 ... Fresh air flow rate control valve (fresh air supply device)
43 ... Switching valve 50 ... Control unit 51 ... Valve timing changing device

Claims (8)

With an even number of cylinders,
An EGR passage that connects the exhaust passage and the intake passage and returns the EGR gas that is a part of the exhaust gas to the intake passage.
It is equipped with an EGR control valve that opens and closes this EGR passage.
A control method for an internal combustion engine that controls the EGR control valve in the closing direction in response to the decrease in the target EGR rate when the EGR decreases, which is set according to the engine operating state.
To one cylinder group of the combustion order odd cylinder group or even-numbered cylinder group comprising a fresh air supply equipment capable of supplying fresh air that does not contain the EGR gas,
The fresh air supply device includes a fresh air supply passage that introduces fresh air into one of the cylinder groups without passing through the EGR introduction port that connects the EGR passage to the intake passage, and a new air supply passage that opens and closes the fresh air supply passage. Has an air flow control valve ,
A control method for an internal combustion engine, characterized in that fresh air is supplied from the fresh air supply device to one of the cylinder groups to continue combustion, while combustion is stopped in the other cylinder group. The method for controlling an internal combustion engine according to claim 1 , wherein when the EGR is lowered, the fresh air flow rate control valve is controlled in the opening direction. A turbocharger equipped with a compressor that is installed in the intake passage on the downstream side of the EGR inlet and supercharges the intake air.
It is provided in the intake passage on the downstream side of the compressor, and is equipped with a throttle valve that opens and closes this intake passage.
The method for controlling an internal combustion engine according to claim 1 or 2 , wherein when the EGR is lowered, the throttle valve is controlled in the opening direction. When the EGR rate drops below a predetermined value when the EGR drops, combustion of the other cylinder group is restarted, the throttle valve is controlled in the closing direction, and the fresh air flow rate control valve is closed. The control method for an internal combustion engine according to claim 3 , wherein the method is to be used. The supercharger is provided in an exhaust passage and includes a turbine that is driven by exhaust energy to rotate and drive the compressor.
A wastegate valve that adjusts the boost pressure is provided in the bypass passage that bypasses the turbine.
When an acceleration request is detected when the EGR is lowered, combustion of the other cylinder group is restarted, and the opening of the throttle valve is controlled in response to the acceleration request, and the wastegate valve is controlled in the closing direction. The method for controlling an internal combustion engine according to claim 3 or 4 , wherein the fresh air flow control valve is controlled in a closing direction. A fresh air introduction route for introducing fresh air to one of the cylinder groups via the fresh air supply passage, and
It has a switching valve that switches between communication and interruption with the EGR introduction path that introduces EGR gas from the EGR passage to the other cylinder group via the intake passage.
The method for controlling an internal combustion engine according to any one of claims 1 to 5 , wherein when the EGR is lowered, the fresh air introduction path and the EGR introduction path are cut off by the switching valve. Equipped with a valve timing changer that can change the valve timing of the intake valve or exhaust valve
When the EGR decreases, fresh air is supplied from the fresh air supply device to one of the cylinder groups to continue combustion, while combustion is stopped in the other cylinder group and the valve overlap tends to increase. The method for controlling an internal combustion engine according to any one of claims 1 to 6 , wherein the valve timing changing device is controlled. With an even number of cylinders,
An EGR passage that connects the exhaust passage and the intake passage and returns the EGR gas that is a part of the exhaust gas to the intake passage.
An EGR control valve that opens and closes this EGR passage,
A fresh air supply device capable of supplying fresh air containing no EGR gas to one of the cylinder groups having an odd-numbered combustion sequence or an even-numbered cylinder group,
When the target EGR rate set according to the engine operating state decreases, the EGR control valve is controlled in the direction of closing according to the decrease in the target EGR rate, and the new cylinder group is used. It is equipped with a control unit that supplies fresh air from the air supply device to continue combustion, while the other cylinder group stops combustion.
The fresh air supply device includes a fresh air supply passage that introduces fresh air into one of the cylinder groups without passing through the EGR introduction port that connects the EGR passage to the intake passage, and a new air supply passage that opens and closes the fresh air supply passage. A control device for an internal combustion engine , which comprises an air flow rate control valve .

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