JP4930332B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that controls a variable valve mechanism that changes the opening / closing characteristics of an intake valve and an external EGR device.

  2. Description of the Related Art As a variable valve mechanism for an internal combustion engine, a valve operating angle variable mechanism that changes a valve opening period (valve operating angle) that is an opening / closing characteristic of an intake valve is known. There is also known an external EGR device that takes a part of exhaust gas as an external EGR gas from an exhaust passage of the internal combustion engine and recirculates the external EGR gas to the intake passage of the internal combustion engine.

When the operating state of the internal combustion engine is on the low load region side, the valve operating angle of the intake valve is set to a small operating angle to improve fuel consumption, and when the operating state of the internal combustion engine is on the high load region side. Discloses a technique for increasing the valve operating angle of the intake valve and introducing external EGR gas to improve fuel efficiency and reduce NOx (see, for example, Patent Document 1).
JP 2002-89341 A JP 2000-73803 A JP-A-2005-351154

  By the way, when the operating state of the internal combustion engine shifts from the low load region side to the high load region side, the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle. At this time, a large amount of external EGR gas is required simultaneously with switching of the valve operating angle of the intake valve. However, since the external EGR gas has a long recirculation path until it is recirculated to the internal combustion engine, it takes time until the external EGR gas actually reaches the internal combustion engine even after the introduction of the external EGR gas is started. There is a recirculation delay until the required amount of external EGR gas is supplied to the internal combustion engine when the operating state is on the high load region side.

  Therefore, immediately after the operating state of the internal combustion engine shifts to the high load region side, that is, immediately after the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle, the external EGR gas becomes insufficient. Then, due to the shortage of external EGR gas, the heat capacity of the in-cylinder gas of the internal combustion engine does not increase, the combustion temperature does not decrease, and the cooling loss does not decrease. For this reason, the effect of the improvement of the fuel consumption obtained when cooling loss falls cannot be acquired. In addition, the control of the intake air amount fluctuates while a recirculation delay occurs until the required amount of external EGR gas is supplied to the internal combustion engine when the operating state of the internal combustion engine is on the high load region side. Therefore, the control becomes difficult because the amount of external EGR gas introduced must be accommodated, and this also makes it impossible to improve fuel consumption.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to control the amount of external EGR gas when a valve operating angle of an intake valve is switched from a small operating angle to a large operating angle in a control device for an internal combustion engine. The purpose is to provide a technique for improving fuel efficiency without causing abrupt changes.

In the present invention, the following configuration is adopted. That is, the present invention
An intake valve valve operating angle variable mechanism capable of switching the valve operating angle of the intake valve in at least two stages;
An intake valve valve timing variable mechanism capable of changing the valve timing of the intake valve;
An external EGR device that takes in a part of the exhaust gas from the exhaust passage of the internal combustion engine as an external EGR gas and recirculates the external EGR gas to the intake passage of the internal combustion engine;
With
When the operating state of the internal combustion engine is on the low load region side, the valve operating angle of the intake valve is set to a small operating angle, and the valve timing of the intake valve is set to the closing timing of the intake valve from the bottom dead center. As soon as possible the timing of early closing,
When the operating state of the internal combustion engine is on the high load region side, the valve operating angle of the intake valve is set to a large operating angle and the operating state of the internal combustion engine is on the low load region side. A control device for an internal combustion engine that recirculates more than the case,
When the operating state of the internal combustion engine shifts to a predetermined region within the low load region side and before the high load region side, the valve timing of the intake valve is determined according to the opening / closing timing of the intake valve. At a timing that is retarded from the case of being on the low load region side, introduction of the external EGR gas toward the required amount required when the operating state of the internal combustion engine is on the high load region side is started. This is a control device for an internal combustion engine.

  When the operating state of the internal combustion engine shifts from the low load region side to the high load region side, the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle. Further, at this time, a large amount of external EGR gas is required at the same time when the valve operating angle of the intake valve is switched, as compared with the case where the operating state of the internal combustion engine is on the low load region side. However, since the external EGR gas has a long recirculation path until it is recirculated to the internal combustion engine, it takes time until the external EGR gas actually reaches the internal combustion engine even after the introduction of the external EGR gas is started. There is a recirculation delay until the required amount of external EGR gas is supplied to the internal combustion engine when the operating state is on the high load region side.

  Therefore, immediately after the operating state of the internal combustion engine shifts to the high load region side, that is, immediately after the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle, the external EGR gas becomes insufficient. Then, due to the shortage of external EGR gas, the heat capacity of the in-cylinder gas of the internal combustion engine does not increase, the combustion temperature does not decrease, and the cooling loss does not decrease. For this reason, the effect of the improvement of the fuel consumption obtained when cooling loss falls cannot be acquired. In addition, the control of the intake air amount fluctuates while a recirculation delay occurs until the required amount of external EGR gas is supplied to the internal combustion engine when the operating state of the internal combustion engine is on the high load region side. Therefore, the control becomes difficult because the amount of external EGR gas introduced must be accommodated, and this also makes it impossible to improve fuel consumption.

  In contrast, when the operating state of the internal combustion engine is on the low load region side, the external EGR gas is gradually introduced, and the operating state of the internal combustion engine is switched when the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle. It is also conceivable that the required amount of external EGR gas required when the engine is on the high load region side can be supplied to the internal combustion engine. However, when the operating state of the internal combustion engine is on the low load region side, the valve operating angle of the intake valve is a small operating angle, and the intake flow disappears early, so there is little turbulence in the cylinder gas of the internal combustion engine. It cannot be formed. For this reason, the tolerance with respect to a combustion deterioration factor is low. Since the introduction of the external EGR gas is a combustion deterioration factor, a large amount of the external EGR gas cannot be introduced in a state where resistance to the combustion deterioration factor is low. Therefore, when the valve operating angle of the intake valve is a small operating angle, it is considered difficult to introduce the required amount of external EGR gas required when the operating state of the internal combustion engine is on the high load region side. It was.

  Therefore, in the present invention, when the operating state of the internal combustion engine shifts to a predetermined region before the high load region side within the low load region side, the valve timing of the intake valve is determined based on the opening / closing timing of the intake valve. The timing is delayed more than when the engine is on the low load region side, and introduction of the external EGR gas is started toward the required amount when the operating state of the internal combustion engine is on the high load region side.

Here, the predetermined region is a state in which the operation state of the internal combustion engine is in the low load region side, and when the operation state shifts to a higher load direction than that, the operation state shifts to the high load region side. This is the area in front of the load area.

  According to the present invention, when the operating state of the internal combustion engine shifts to a predetermined region in the low load region side, the external EGR gas is directed to the required amount required when the internal combustion engine is in the high load region side. The introduction is started and the amount of external EGR gas is increased. For this reason, when the operating state of the internal combustion engine actually shifts from the predetermined region to the high load region side, an amount of external EGR gas that is close to the required amount required when the operating state of the internal combustion engine is on the high load region side is It is already installed. Therefore, there is no shortage of external EGR gas immediately after the operating state of the internal combustion engine shifts to the high load region side, that is, immediately after the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle. Therefore, sufficient external EGR gas is introduced, the heat capacity of the in-cylinder gas of the internal combustion engine increases, the combustion temperature decreases, and the cooling loss decreases. For this reason, the effect of the improvement of a fuel consumption is acquired because cooling loss falls. In addition, since there is no recirculation delay until the required amount of external EGR gas is supplied to the internal combustion engine when the operating state of the internal combustion engine is on the high load region side, the intake air amount can be easily controlled. This can also improve fuel consumption.

  However, when the operating state of the internal combustion engine shifts to a predetermined region within the low load region as described above, increasing the amount of external EGR gas is a cause of combustion deterioration, and there is a risk that combustion will deteriorate if this condition remains unchanged. Therefore, according to the present invention, when the operating state of the internal combustion engine shifts to a predetermined region within the low load region side, the valve timing of the intake valve is changed so that the opening / closing timing of the intake valve is changed to the low load region side. The timing is delayed more than in some cases. According to this, the opening timing of the intake valve can be delayed, and the closing timing of the intake valve can be closed near the bottom dead center. For this reason, by delaying the opening timing of the intake valve, the friction loss due to the intake air passing through the intake valve when the intake valve is opened is converted into temperature, and the in-cylinder temperature of the internal combustion engine rises. Further, by closing the closing timing of the intake valve near the bottom dead center, the actual compression ratio is increased and the in-cylinder temperature of the internal combustion engine is increased. By increasing the in-cylinder temperature of the internal combustion engine due to these two factors, combustion is improved and resistance to the deterioration factor of combustion is increased. Therefore, in the present invention, since the resistance to the combustion deterioration factor is high, the combustion does not deteriorate even if the external EGR gas that is the combustion deterioration factor is increased, and a large amount of external EGR gas close to the required amount can be introduced.

  As described above, according to the present invention, when the valve working angle of the intake valve is switched from the small working angle to the large working angle, the amount of external EGR gas can be smoothly introduced without abruptly changing the external EGR gas amount. The fuel efficiency can be improved immediately after switching the valve operating angle to the large operating angle.

  When the operating state of the internal combustion engine shifts to a predetermined region before the high load region within the low load region side, the valve timing of the intake valve is determined based on the valve opening timing of the intake valve. Is delayed later than when the engine is on the low load region side, and the closing timing of the intake valve is close to the bottom dead center when the operating state of the internal combustion engine is on the low load region side. Good.

  According to the present invention, when the operating state of the internal combustion engine shifts to a predetermined region within the low load region side, the opening timing of the intake valve is delayed and the closing timing of the intake valve is closed near the bottom dead center. . Therefore, by delaying the opening timing of the intake valve, the friction loss due to the intake air passing through the intake valve when the intake valve is opened is converted into temperature, and the in-cylinder temperature of the internal combustion engine rises. Further, by closing the closing timing of the intake valve near the bottom dead center, the actual compression ratio is increased and the in-cylinder temperature of the internal combustion engine is increased. By increasing the in-cylinder temperature of the internal combustion engine due to these two factors, the combustion is improved and the resistance to the combustion deterioration factor can be increased.

When the operating state of the internal combustion engine shifts to a predetermined region within the low load region side and before the high load region side, the valve timing of the intake valve is determined according to the opening / closing timing of the intake valve. The retard amount of the opening / closing timing of the intake valve when the timing is retarded relative to that in the low load region side may be changed according to the engine speed of the internal combustion engine.

  According to the present invention, the retard amount of the opening / closing timing of the intake valve is changed according to the engine speed of the internal combustion engine.

  When the operating state of the internal combustion engine shifts to a predetermined region, when the engine speed of the internal combustion engine is high, the in-cylinder gas of the internal combustion engine is likely to be turbulent and has high resistance to combustion deterioration factors. For this reason, in this case, the retard amount of the opening / closing timing of the intake valve for increasing the resistance to the combustion deterioration factor can be reduced. Therefore, by reducing the retard amount of the opening / closing timing of the intake valve and making the closing timing of the intake valve as close as possible, the pump loss can be reduced and the reduction in fuel consumption can be suppressed.

  On the other hand, when the operating state of the internal combustion engine shifts to a predetermined region, when the engine speed of the internal combustion engine is low, the in-cylinder gas of the internal combustion engine is less likely to be disturbed, and the resistance to the combustion deterioration factor is low. In addition, when the operating state of the internal combustion engine shifts to the high load region side from this case, the operating state of the internal combustion engine becomes a state in which knocking at a low rotation and high load is likely to occur immediately after the transition, so that the occurrence of knocking is suppressed. A larger amount of external EGR gas is required. Therefore, in this case, in order to maximize the resistance against the cause of combustion deterioration, the retard amount of the intake valve opening / closing timing is delayed, the intake valve opening timing is delayed, and the intake valve closing timing is lowered. I want to increase it as close as possible to the point close. Therefore, by increasing the retard amount of the opening and closing timing of the intake valve, delaying the opening timing of the intake valve and making the closing timing of the intake valve as close as possible to closing near the bottom dead center, resistance to combustion deterioration factors can be obtained. Can be increased.

  As described above, according to the present invention, when the engine speed of the internal combustion engine is high, a reduction in fuel consumption can be suppressed even slightly, and the resistance to combustion deterioration factors for introducing the external EGR gas can be maintained at a high level. .

  The retard amount may be increased as the engine speed of the internal combustion engine is lowered.

  According to the present invention, when the engine speed of the internal combustion engine is high, the retard amount of the opening / closing timing of the intake valve is decreased, and the closing timing of the intake valve is made as close as possible to reduce the pump loss. , Can reduce fuel consumption. Also, when the engine speed of the internal combustion engine is low, the retard amount of the opening / closing timing of the intake valve is increased so that the opening timing of the intake valve is delayed and the closing timing of the intake valve is made as close as possible to close near the bottom dead center. Thereby, the tolerance with respect to a combustion deterioration factor can be improved more.

  When the operating state of the internal combustion engine shifts to a predetermined region within the low load region side and before the high load region side, the valve timing of the intake valve is determined according to the opening / closing timing of the intake valve. The retard amount of the opening / closing timing of the intake valve when the timing is retarded compared to the case where it is on the low load region side may be changed according to the required amount of external EGR gas.

  According to the present invention, the retard amount of the opening / closing timing of the intake valve is changed according to the required amount of external EGR gas.

  When the required amount of external EGR gas is small, the amount of increase in external EGR gas that is a cause of combustion deterioration is small, and the resistance to the combustion deterioration factor may be relatively low. For this reason, in this case, the retard amount of the opening / closing timing of the intake valve for increasing the resistance to the combustion deterioration factor can be reduced. Therefore, by reducing the retard amount of the opening / closing timing of the intake valve and making the closing timing of the intake valve as close as possible, the pump loss can be reduced and the reduction in fuel consumption can be suppressed.

  On the other hand, when the required amount of external EGR gas is large, the amount of increase in external EGR gas, which is a cause of combustion deterioration, is large, and it is preferable that resistance to the deterioration factor of combustion is as high as possible. Therefore, in this case, in order to maximize the resistance against the cause of combustion deterioration, the retard amount of the intake valve opening / closing timing is delayed, the intake valve opening timing is delayed, and the intake valve closing timing is lowered. I want to increase it as close as possible to the point close. Therefore, by increasing the retard amount of the opening and closing timing of the intake valve, delaying the opening timing of the intake valve and making the closing timing of the intake valve as close as possible to closing near the bottom dead center, resistance to combustion deterioration factors can be obtained. Can be increased.

  As described above, according to the present invention, when the required amount of the external EGR gas is small, it is possible to suppress a reduction in fuel consumption even slightly.

  The retard amount may be increased as the required amount of external EGR gas increases.

  According to the present invention, when the required amount of external EGR gas is small, the retard amount of the opening / closing timing of the intake valve is decreased, and the closing timing of the intake valve is made as close as possible to reduce the pump loss. , Can reduce fuel consumption. When the required amount of external EGR gas is large, the retard amount of the opening / closing timing of the intake valve is increased so that the opening timing of the intake valve is delayed and the closing timing of the intake valve is as close as possible to closing near the bottom dead center. Thereby, the tolerance with respect to a combustion deterioration factor can be improved more.

In the present invention, the following configuration is adopted. That is, the present invention
An intake valve valve operating angle variable mechanism capable of switching the valve operating angle of the intake valve in at least two stages;
An intake valve valve timing variable mechanism capable of changing the valve timing of the intake valve;
An external EGR device that takes in a part of the exhaust gas from the exhaust passage of the internal combustion engine as an external EGR gas and recirculates the external EGR gas to the intake passage of the internal combustion engine;
With
When the operating state of the internal combustion engine is on the low load region side, the valve operating angle of the intake valve is set to a small operating angle, and the valve timing of the intake valve is set to the closing timing of the intake valve from the bottom dead center. As soon as possible the timing of early closing,
When the operating state of the internal combustion engine is on the high load region side, the valve operating angle of the intake valve is set to a large operating angle and the operating state of the internal combustion engine is on the low load region side. A control device for an internal combustion engine that recirculates more than the case,
The external EGR device includes an EGR cooler that cools the external EGR gas that circulates in the external EGR device, a bypass passage that bypasses the EGR cooler to the external EGR gas that circulates in the external EGR device, and the bypass A bypass valve for opening and closing the passage,
When the operating state of the internal combustion engine is shifted to a predetermined region within the low load region side and before the high load region side, the external EGR gas is used when the operating state of the internal combustion engine is on the high load region side. The introduction starts toward the required amount, and the amount of the introduced external EGR gas reaches a predetermined amount that becomes a threshold value that requires the temperature of the external EGR gas to be raised so as not to deteriorate the combustion state of the internal combustion engine. Then, the internal combustion engine control apparatus is characterized in that the bypass valve is opened.

  In the present invention, the external EGR gas is required when the operating state of the internal combustion engine is on the high load region side when the operating state of the internal combustion engine shifts to a predetermined region in the low load region side and before the high load region side. When the introduced external EGR gas amount reaches a predetermined amount that becomes a threshold value that requires the temperature of the external EGR gas to be increased so as not to deteriorate the combustion state of the internal combustion engine, the bypass valve Was decided to open.

  Here, the predetermined amount means that when an external EGR gas amount larger than that is introduced, the introduced external EGR gas amount does not deteriorate the combustion state of the internal combustion engine, so that the temperature of the external EGR gas needs to be raised. This is the amount of external EGR gas that becomes the threshold value.

  According to the present invention, when the operating state of the internal combustion engine shifts to a predetermined region in the low load region side, the external EGR gas is directed to the required amount required when the internal combustion engine is in the high load region side. The introduction is started and the amount of external EGR gas is increased. For this reason, when the operating state of the internal combustion engine actually shifts from the predetermined region to the high load region side, an amount of external EGR gas that is close to the required amount required when the operating state of the internal combustion engine is on the high load region side is It is already installed. Therefore, there is no shortage of external EGR gas immediately after the operating state of the internal combustion engine shifts to the high load region side, that is, immediately after the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle. Therefore, sufficient external EGR gas is introduced, the heat capacity of the in-cylinder gas of the internal combustion engine increases, the combustion temperature decreases, and the cooling loss decreases. For this reason, the effect of the improvement of a fuel consumption is acquired because cooling loss falls. In addition, since there is no recirculation delay until the required amount of external EGR gas is supplied to the internal combustion engine when the operating state of the internal combustion engine is on the high load region side, the intake air amount can be easily controlled. This can also improve fuel consumption.

  However, when the operating state of the internal combustion engine shifts to a predetermined region within the low load region as described above, increasing the amount of external EGR gas is a cause of combustion deterioration, and there is a risk that combustion will deteriorate if this condition remains unchanged. Therefore, according to the present invention, when the introduced external EGR gas amount reaches a predetermined amount, the bypass valve is opened. According to this, the EGR cooler is bypassed by the external EGR gas, and the external EGR gas passes through the bypass passage. The external EGR gas that bypasses the EGR cooler in this way is high temperature because it is not cooled by the EGR cooler. Therefore, high temperature external EGR gas is introduced into the internal combustion engine. When the high-temperature external EGR gas is introduced, the in-cylinder temperature of the internal combustion engine increases because the heat capacity of the high-temperature external EGR gas is small. As a result, the in-cylinder temperature of the internal combustion engine rises, so that combustion is improved and resistance to combustion deterioration factors is increased. Therefore, in the present invention, since the resistance to the combustion deterioration factor is high, the combustion does not deteriorate even if the external EGR gas that is the combustion deterioration factor is increased, and a large amount of external EGR gas close to the required amount can be introduced.

  Here, in the present invention, when the operating state of the internal combustion engine shifts to a predetermined region within the low load region side, the valve timing of the intake valve is set to the timing of early closing when the closing timing of the intake valve is earlier than the bottom dead center. Is maintained. For this reason, even when the operating state of the internal combustion engine shifts to a predetermined region in the low load region side, the pump loss is reduced by closing the intake valve earlier than the bottom dead center. In addition, fuel consumption can be improved.

  As described above, according to the present invention, when the valve working angle of the intake valve is switched from the small working angle to the large working angle, the amount of external EGR gas can be smoothly introduced without abruptly changing the external EGR gas amount. It is possible to improve fuel efficiency before and after switching the valve operating angle to a large operating angle.

  According to the present invention, in the control device for an internal combustion engine, when the valve operating angle of the intake valve is switched from a small operating angle to a large operating angle, the external EGR gas amount is not changed suddenly, and fuel consumption can be improved.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the control device for an internal combustion engine according to the present embodiment is applied. An internal combustion engine 1 shown in FIG. 1 is a spark ignition internal combustion engine (gasoline engine) using gasoline as fuel.

  The cylinder head 2 of the internal combustion engine 1 is provided with an intake port 4 and an exhaust port 5 that communicate with the combustion chamber 3. The cylinder head 2 is provided with an intake valve 6 that opens and closes the intake port 4 and an exhaust valve 7 that opens and closes the exhaust port 5.

  The intake valve 6 is provided with a variable valve mechanism that changes the opening / closing characteristics of the intake valve 6. As this variable valve mechanism, an intake valve valve operating angle variable mechanism 8 that changes a valve opening period (valve operating angle), which is an opening / closing characteristic of the intake valve 6, and an opening / closing timing (valve timing), which is an opening / closing characteristic of the intake valve 6. And an intake valve valve timing variable mechanism 9 for changing the above.

  The intake valve valve operating angle variable mechanism 8 in the present embodiment is a mechanism that changes the valve operating angle in two stages together with the lift amount of the intake valve 6. Here, the smaller lift angle and the valve operating angle of the intake valve 6 are referred to as a small operating angle, and the larger lift amount and the valve operating angle of the intake valve 6 are referred to as a large operating angle.

  In the present embodiment, the intake valve valve operating angle variable mechanism 8 is a mechanism that only changes the valve operating angle in two stages together with the lift amount of the intake valve 6. It is only necessary to be able to change it to at least two stages. For example, it can be applied to those in which the valve working angle can be changed to three or more stages, and even if the valve working angle can be changed continuously, the valve working angle is instantaneously increased. This can be applied when changing to a farther working angle.

  On the other hand, the intake valve valve timing variable mechanism 9 in the present embodiment is a mechanism that continuously changes the opening / closing timing of the intake valve 6 while keeping the valve operating angle of the intake valve 6 constant.

  The cylinder head 2 is provided with a spark plug 10 that generates a spark in the cylinder of the internal combustion engine 1.

  An intake pipe 11 that communicates with the intake port 4 and an exhaust pipe 12 that communicates with the exhaust port 5 are connected to the cylinder head 2. The intake pipe 11 is provided with a fuel injection valve 13 that injects fuel toward the intake port 4. An air flow meter 14 is provided in the intake pipe 11.

  The internal combustion engine 1 is provided with an external EGR device 30 that recirculates a part of the exhaust gas flowing through the exhaust pipe 12 to the intake pipe 11. The external EGR device 30 includes an external EGR passage 31, an external EGR valve 32, and an external EGR cooler 33.

  The external EGR passage 31 connects the exhaust pipe 12 and the intake pipe 11. Exhaust gas is fed into the internal combustion engine 1 through the external EGR passage 31. In this embodiment, the exhaust gas recirculated through the external EGR passage 31 is referred to as external EGR gas.

  The external EGR valve 32 is disposed in the external EGR passage 31 and adjusts the amount of external EGR gas flowing through the external EGR passage 31 by adjusting the passage cross-sectional area of the external EGR passage 31.

The external EGR cooler 33 is disposed in the external EGR passage 31 and exchanges heat between the external EGR gas passing through the external EGR cooler 33 and the engine coolant of the internal combustion engine 1 to lower the temperature of the external EGR gas. . The external EGR cooler 33 in this embodiment corresponds to the EGR cooler of the present invention.

  The internal combustion engine 1 configured as described above is provided with an ECU 15 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 15 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  Various sensors such as an air flow meter 14, a water temperature sensor 16 attached to the internal combustion engine 1, and a crank position sensor 17 are connected to the ECU 15 through electrical wiring, and output signals of these various sensors are input to the ECU 15. It has become.

  The ECU 15 electrically controls the intake valve valve operating angle variable mechanism 8, the intake valve valve timing variable mechanism 9, the ignition plug 10, the fuel injection valve 13, and the external EGR valve 32 based on the output signals of various sensors. Is possible.

  Next, control according to the operation state of the conventional internal combustion engine 1 will be described. FIG. 2 is a schematic view illustrating a control state according to the operation state of the internal combustion engine 1 in the related art. 2 represents the engine speed of the internal combustion engine 1, and the vertical axis represents the engine load of the internal combustion engine 1.

  In FIG. 2, when the operating state of the internal combustion engine 1 is in the low load region side L, the amount of intake air can be reduced, so a small operating angle is selected as the valve operating angle of the intake valve 6. At the same time, in order to reduce pump loss and improve fuel efficiency, the valve timing of the intake valve is set to an early closing timing at which the intake valve closes earlier than the bottom dead center. In order to further improve fuel efficiency, external EGR gas may be supplied to the internal combustion engine 1 in some cases.

  On the other hand, when the operating state of the internal combustion engine 1 is in the high load region side H, a large amount of intake air is required, so a large operating angle is selected as the valve operating angle of the intake valve 6. At the same time, when the operating state of the internal combustion engine 1 is on the low load region side L in order to increase the heat capacity of the in-cylinder gas of the internal combustion engine 1 and lower the combustion temperature to reduce the cooling loss and improve the fuel efficiency. In comparison, a large amount of external EGR gas is supplied to the internal combustion engine 1.

  In order to realize such a control state shown in FIG. 2, the intake valve valve operating angle variable mechanism 8, the intake valve valve timing variable mechanism 9, and the external EGR valve 32 are appropriately controlled according to the operating state of the internal combustion engine 1. I am doing so.

  By the way, when the operating state of the internal combustion engine 1 shifts from the low load region side L to the high load region side H, the valve operating angle of the intake valve 6 is changed from a small operating angle using the intake valve valve operating angle variable mechanism 8. Switch to large working angle. At this time, simultaneously with switching of the valve operating angle of the intake valve 6, a larger amount of external EGR gas is required than when the operating state of the internal combustion engine 1 is on the low load region side L.

  FIG. 3 is a diagram showing a time change of the external EGR gas amount when the valve operating angle of the intake valve 6 is switched from a small operating angle to a large operating angle in the related art. In FIG. 3, the solid thin line is the required amount (target amount) of the external EGR gas, and the solid thick line is the actual external EGR gas amount.

As shown in FIG. 3, simultaneously with the switching of the valve operating angle of the intake valve 6, a larger amount of external EGR gas is required than when the operating state of the internal combustion engine 1 is on the low load region side L. However, since the external EGR gas has a long recirculation path until it is recirculated to the internal combustion engine 1, the external EGR gas is actually supplied to the internal combustion engine 1 even after the external EGR valve 32 is controlled to open and the introduction of the external EGR gas is started. It takes time for the gas to reach, and a recirculation delay occurs until the required amount of external EGR gas is supplied to the internal combustion engine 1 when the operating state of the internal combustion engine 1 is on the high load region side H. ing. For this reason, as shown in FIG. 3, the external EGR gas amount gradually increases toward the required amount after the switching time of the valve operating angle of the intake valve 6.

  Therefore, immediately after the operating state of the internal combustion engine 1 shifts to the high load region side H, that is, immediately after the valve operating angle of the intake valve 6 is switched from the small operating angle to the large operating angle, the external EGR gas becomes insufficient. Then, due to the shortage of external EGR gas, the heat capacity of the in-cylinder gas of the internal combustion engine 1 does not increase, the combustion temperature does not decrease, and the cooling loss does not decrease. For this reason, the effect of the improvement of the fuel consumption obtained when cooling loss falls cannot be acquired. In addition, while there is a recirculation delay until the required amount of external EGR gas is supplied to the internal combustion engine 1 when the operating state of the internal combustion engine 1 is on the high load region side H, the intake air amount Since it is necessary to cope with the amount of external EGR gas introduced that fluctuates, the control becomes difficult, and this also makes it impossible to improve the fuel consumption. In addition, there is a concern that torque shock may occur due to a shortage of external EGR gas.

  On the other hand, when the operating state of the internal combustion engine 1 is on the low load region side L, external EGR gas is gradually introduced, and the internal combustion engine is switched when the valve operating angle of the intake valve 6 is switched from a small operating angle to a large operating angle. It is also conceivable to allow the required amount of external EGR gas to be supplied to the internal combustion engine 1 when the operating state of 1 is on the high load region side H. However, when the operating state of the internal combustion engine 1 is on the low load region side L, the valve operating angle of the intake valve 6 is a small operating angle, and the intake air flow disappears at an early stage. Only a little turbulence can be formed. For this reason, the tolerance with respect to a combustion deterioration factor is low. Since the introduction of the external EGR gas is a combustion deterioration factor, a large amount of the external EGR gas cannot be introduced in a state where resistance to the combustion deterioration factor is low. Nevertheless, if a large amount of external EGR gas is introduced in a state where the resistance to the deterioration factor of the combustion is low, the fluctuation of combustion becomes large, and in the worst case, there is a possibility that the engine may be misfired and the engine is stopped. Therefore, when the valve operating angle of the intake valve 6 is a small operating angle, it is difficult to introduce the required amount of external EGR gas required when the operating state of the internal combustion engine 1 is on the high load region side H. It was thought.

  Therefore, in this embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P before the high load region side H within the low load region side L, the intake valve 6 is changed using the intake valve valve timing variable mechanism 9. When the opening timing of the intake valve 6 is later than when the operating state of the internal combustion engine 1 is in the low load region L, the closing timing of the intake valve 6 is low when the operating state of the internal combustion engine 1 is low. The closing timing is close to the bottom dead center, which is later than that in the region L. At the same time, the external EGR valve 32 is controlled to open to start introducing the external EGR gas toward the required amount when the operating state of the internal combustion engine 1 is on the high load region side H. .

  A specific control according to the operating state of the internal combustion engine 1 in this embodiment will be described. FIG. 4 is a schematic view illustrating a control state according to the operation state of the internal combustion engine 1 in the present embodiment. The horizontal axis of FIG. 4 represents the engine speed of the internal combustion engine 1, and the vertical axis represents the engine load of the internal combustion engine 1.

  As shown in FIG. 4, the predetermined region P is one in which the operation state of the internal combustion engine 1 is in the low load region side L, and when the operation state shifts to a higher load direction than that, the operation state becomes high load. This is a region before the high load region side H that shifts to the region side H.

In FIG. 4, when the operating state of the internal combustion engine 1 is on the low load region side L, which is on the low load side than the predetermined region P, the amount of intake air can be reduced as in the conventional case. A small working angle is selected. At the same time, in order to reduce pump loss and improve fuel efficiency, the valve timing of the intake valve 6 is set to an early closing timing at which the intake valve 6 is closed earlier than the bottom dead center. In order to further improve fuel efficiency, external EGR gas may be supplied to the internal combustion engine 1 in some cases.

  On the other hand, when the operating state of the internal combustion engine 1 is in the high load region side H, a large amount of intake air is required as in the conventional case, so a large operating angle is selected as the valve operating angle of the intake valve 6. At the same time, when the operating state of the internal combustion engine 1 is on the low load region side L in order to increase the heat capacity of the in-cylinder gas of the internal combustion engine 1 and lower the combustion temperature to reduce the cooling loss and improve the fuel efficiency. In comparison, a large amount of external EGR gas is supplied to the internal combustion engine 1.

  In the present embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region L, the intake valve 6 remains selected with the small operation angle selected as the valve operation angle of the intake valve 6. When the opening timing of the intake valve 6 is later than when the operating state of the internal combustion engine 1 is in the low load region L, the closing timing of the intake valve 6 is low when the operating state of the internal combustion engine 1 is low. The timing is set to close in the vicinity of the bottom dead center, which is later than that in the region side L. At the same time, introduction of the external EGR gas toward the required amount required when the operating state of the internal combustion engine 1 is on the high load region side H is started.

  FIG. 5 is a diagram for explaining how the valve timing of the intake valve 6 is changed when the operating state of the internal combustion engine 1 shifts to the predetermined region P within the low load region L. In this embodiment, as shown in FIG. 5, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the valve timing of the intake valve 6 is controlled by the intake valve valve timing variable mechanism 9. From the early closing of the valve closing timing (IVC) of the intake valve 6 before the transition earlier than the bottom dead center, the valve opening timing (IVO) of the intake valve 6 after the transition is delayed and the valve closing timing of the intake valve 6 is closed. The valve timing is controlled so that (IVC) is closed near the bottom dead center.

  That is, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region L, the opening timing of the intake valve 6 is delayed and the closing timing of the intake valve 6 is closed near the bottom dead center. Become. Thus, by delaying the opening timing of the intake valve 6, the friction loss due to the intake air passing through the intake valve 6 when the intake valve is opened is converted to temperature, and the in-cylinder temperature of the internal combustion engine 1 is increased. Further, by closing the intake valve 6 close to the bottom dead center, the actual compression ratio is increased and the in-cylinder temperature of the internal combustion engine 1 is increased. By increasing the in-cylinder temperature of the internal combustion engine 1 due to these two factors, the combustion is improved and the resistance to the combustion deterioration factor is increased.

  FIG. 6 shows the case where the closing timing (IVC) of the intake valve 6 is closed earlier than the bottom dead center, and the opening timing (IVO) of the intake valve 6 is delayed and the intake valve 6 is opened as in this embodiment. It is a figure which shows the external EGR gas amount until the combustion fluctuation | variation becomes large in the case where the valve closing time (IVC) of this is made close to a bottom dead center. The broken line in FIG. 6 indicates the characteristics when the closing timing of the intake valve 6 is early closed earlier than the bottom dead center, and the solid line delays the opening timing of the intake valve 6 and lowers the closing timing of the intake valve 6. The characteristics when closing near the dead center are shown.

  As shown in FIG. 6, when the opening timing of the intake valve 6 is delayed and the closing timing of the intake valve 6 is closed near the bottom dead center, the closing timing of the intake valve 6 is closed earlier than the bottom dead center. Compared with the case of making it, even if the external EGR gas, which is a cause of deterioration of combustion, is greatly increased, the fluctuation of combustion is hardly increased. In this way, when the opening timing of the intake valve 6 is delayed and the closing timing of the intake valve 6 is closed near the bottom dead center, since the resistance to combustion deterioration is high, a large amount near the required amount is required. External EGR gas can be introduced.

  Since a large amount of external EGR gas close to the required amount can be introduced as described above, in this embodiment, when the operating state of the internal combustion engine 1 is in the predetermined region P in the low load region side L, the external EGR gas is The introduction starts toward the required amount required when the operating state of the engine 1 is on the high load region side H.

  FIG. 7 is a diagram showing the time change of the external EGR gas amount when the valve operating angle of the intake valve 6 is switched from the small operating angle to the large operating angle in the present embodiment. In FIG. 7, the solid thin line is the required amount (target amount) of the external EGR gas, and the solid thick line is the actual external EGR gas amount.

  As shown in FIG. 7, in this embodiment, when the operating state of the internal combustion engine 1 is in the predetermined region P, that is, before the operating state of the internal combustion engine 1 shifts to the high load region side H, the amount of external EGR gas is increased. Is done. Therefore, when the operating state of the internal combustion engine 1 actually shifts from the predetermined region P to the high load region side H, an amount close to the required amount required when the operating state of the internal combustion engine 1 is on the high load region side H. The external EGR gas is already introduced. Therefore, when the operating state of the internal combustion engine 1 shifts to the high load region side H, that is, when the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle, the required amount and the actual external EGR gas amount There is almost no deviation. Therefore, immediately after the operating state of the internal combustion engine 1 shifts to the high load region side H, that is, immediately after the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle, there is no shortage of external EGR gas. Therefore, sufficient external EGR gas is introduced, the heat capacity of the in-cylinder gas of the internal combustion engine 1 is increased, the combustion temperature is lowered, and the cooling loss is lowered. For this reason, a fuel consumption can be improved because cooling loss falls. In addition, since there is no reflux delay until the required amount of external EGR gas is supplied to the internal combustion engine 1 when the operating state of the internal combustion engine 1 is on the high load region side H, control of the intake air amount can be performed. This also makes it possible to improve fuel consumption. In addition, there is no concern about torque shock due to the lack of external EGR gas.

  Next, a control routine when the operating state of the internal combustion engine 1 according to this embodiment shifts from the low load region side L to the high load region side H will be described. FIG. 8 is a flowchart showing a control routine when the operating state of the internal combustion engine 1 according to this embodiment shifts from the low load region side L to the high load region side H. This routine is repeatedly executed every predetermined time.

  In step S101, the ECU 15 determines whether or not the operating state of the internal combustion engine 1 exists on the low load region side L that does not include the predetermined region P.

  Specifically, the operating state of the internal combustion engine 1 is applied to the map of FIG. 4 obtained in advance by experiments or the like, and it is determined whether the operating state of the internal combustion engine 1 exists on the low load region side L not including the predetermined region P.

  If it is determined in step S101 that the operating state of the internal combustion engine 1 is in the low load region side L not including the predetermined region P, the process proceeds to step S102. If it is determined in step S101 that the operating state of the internal combustion engine 1 does not exist on the low load region side L that does not include the predetermined region P, this routine is temporarily terminated.

  In step S102, the ECU 15 performs the control in the low load region side mode when the operating state of the internal combustion engine 1 is the low load region side L not including the predetermined region P.

  In the low load region side mode, the valve operating angle of the intake valve 6 is set to a small operating angle using the intake valve valve operating angle variable mechanism 8. Along with this, the intake valve valve timing variable mechanism 9 is used to set the valve timing of the intake valve 6 to the timing of early closing when the intake valve 6 is closed earlier than the bottom dead center. Even in the low load region side mode, the external EGR valve 32 is controlled to be slightly opened so that the required amount of external EGR gas required in accordance with the operating state of the internal combustion engine 1 is increased. The engine 1 may be supplied.

  In step S103, the ECU 15 determines whether or not the operating state of the internal combustion engine 1 has shifted to the predetermined region P within the low load region L.

  Specifically, the operating state of the internal combustion engine 1 is applied to the map of FIG. 4 obtained in advance by experiments or the like, and it is determined whether the operating state of the internal combustion engine 1 has shifted to the predetermined region P within the low load region L.

  If it is determined in step S103 that the operating state of the internal combustion engine 1 has shifted to the predetermined region P, the process proceeds to step S104. If it is determined in step S103 that the operating state of the internal combustion engine 1 does not shift to the predetermined region P, the process returns to step S102.

  In step S104, the ECU 15 performs control in a predetermined region mode when the operating state of the internal combustion engine 1 is the predetermined region P.

  In the predetermined area mode, the intake valve valve timing variable mechanism 9 is used to set the valve timing of the intake valve 6 to a timing at which the opening timing of the intake valve 6 is delayed and the closing timing of the intake valve 6 is closed near the bottom dead center. . At the same time, the external EGR valve 32 is controlled to the open side so that the operation state of the internal combustion engine 1 is higher than that in the case where the operation state of the internal combustion engine 1 is on the low load region side L. The introduction of the required amount of external EGR gas required when it is on the load region side H is started. In the predetermined region mode, the valve operating angle of the intake valve 6 is maintained at a small operating angle.

  In step S105, the ECU 15 determines whether or not the operating state of the internal combustion engine 1 has shifted to a high load region side H that is higher than the predetermined region P.

  Specifically, the operating state of the internal combustion engine 1 is applied to the map of FIG. 4 obtained in advance through experiments or the like, and whether the operating state of the internal combustion engine 1 has shifted to the high load region side H that is higher than the predetermined region P. to decide.

  If it is determined in step S105 that the operating state of the internal combustion engine 1 has shifted to the high load region side H, the process proceeds to step S106. If it is determined in step S105 that the operating state of the internal combustion engine 1 does not shift to the high load region side H, this routine is temporarily terminated.

  In step S106, the ECU 15 controls the high load region side mode when the operating state of the internal combustion engine 1 is the high load region side H.

  In the high load region side mode, the valve operating angle of the intake valve 6 is set to a large operating angle by using the intake valve valve operating angle variable mechanism 8. At the same time, the external EGR valve 32 is controlled to the open side so that the amount of external EGR gas is larger than that in the case where the operating state of the internal combustion engine 1 is on the low load region side L and the internal E1 is in response to the operating state of the internal combustion engine 1. The required amount of external EGR gas is supplied to the internal combustion engine 1. The external EGR gas is introduced from the time when the operating state of the internal combustion engine 1 is in the predetermined region P and the external EGR valve 32 is controlled to be opened, so that the external EGR gas is sufficiently external immediately after the mode transition to the high load region side. An amount of EGR gas is supplied to the internal combustion engine. After the processing of this step, this routine is once ended.

  By executing the above control routine, when the valve operating angle of the intake valve 6 is switched from the small operating angle to the large operating angle, the amount of external EGR gas can be smoothly introduced without abruptly changing the amount of external EGR gas, It is possible to improve fuel efficiency immediately after switching the valve operating angle of the intake valve 6 to a large operating angle.

In this embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P before the high load region side H within the low load region side L, the intake valve 6 is changed using the intake valve valve timing variable mechanism 9. When the opening timing of the intake valve 6 is later than when the operating state of the internal combustion engine 1 is in the low load region L, the closing timing of the intake valve 6 is low when the operating state of the internal combustion engine 1 is low. Region side L
The timing of closing near the bottom dead center is slower than in the case of. However, the present invention is not limited to this, and if resistance to combustion deterioration factors can be increased so that a large amount of external EGR gas can be introduced, the valve timing of the intake valve 6 depends on the opening / closing timing of the intake valve 6. Any timing may be used as long as the timing is retarded as compared with the case of the low load region L.

<Example 2>
Next, Example 2 will be described. Here, a configuration different from the above-described embodiment will be described, and description of the same configuration will be omitted.

  When the operating state of the internal combustion engine 1 is in the low load region side L, if possible, the closing timing of the intake valve 6 should be closed earlier than the bottom dead center to reduce pump loss and improve fuel efficiency. . However, in the first embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the valve opening timing of the intake valve 6 is delayed to increase the resistance against combustion deterioration factors. In addition, the closing timing of the intake valve is closed near the bottom dead center. For this reason, in Example 1, pump loss cannot be reduced and the effect of improving fuel consumption cannot be obtained uniformly.

  However, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, when the engine speed of the internal combustion engine 1 is high, turbulence of the in-cylinder gas of the internal combustion engine 1 is likely to occur, High resistance to burning deterioration factors. For this reason, in this case, the retard amount of the opening / closing timing of the intake valve 6 for enhancing the resistance against the deterioration factor of combustion is decreased, and the closing timing of the intake valve 6 is set to the closing side as soon as possible, whereby the pump I want to reduce the loss and suppress the reduction in fuel consumption as much as possible.

  On the other hand, when the operating state shifts to the predetermined region P in the low load region side L of the internal combustion engine 1, when the engine speed of the internal combustion engine 1 is low, turbulence of the in-cylinder gas of the internal combustion engine 1 is difficult to occur. Low resistance to deterioration factors. Further, when the operating state of the internal combustion engine 1 shifts to the high load region side H from this case, the operating state of the internal combustion engine 1 becomes a state in which knocking at a low rotation and high load is likely to occur immediately after the transition. A greater amount of external EGR gas is required to suppress. Therefore, in this case, in order to maximize the resistance to the combustion deterioration factor, the retard amount of the opening / closing timing of the intake valve 6 is delayed, the opening timing of the intake valve 6 is delayed, and the closing timing of the intake valve 6 is closed. I want to increase as close as possible to close near the bottom dead center.

  Therefore, in this embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the intake valve valve timing variable mechanism 9 is used to change the valve timing of the intake valve 6 to the intake valve 6. The amount of retardation of the opening / closing timing of the intake valve 6 when the opening / closing timing of the internal combustion engine 1 is retarded from the timing when the operating state of the internal combustion engine 1 is in the low load region side L is the engine rotational speed of the internal combustion engine 1. The lower the value, the higher the value.

  According to the present embodiment, when the operating state of the internal combustion engine 1 shifts to a predetermined region in the low load region side L, the turbulence of the in-cylinder gas of the internal combustion engine 1 occurs when the engine speed of the internal combustion engine 1 is high. It is easy to do and has high resistance to the cause of deterioration of combustion. For this reason, in this case, the retard amount of the opening / closing timing of the intake valve 6 for enhancing the resistance against the deterioration factor of combustion is decreased, and the closing timing of the intake valve 6 is set to the closing side as soon as possible, whereby the pump Loss can be reduced and reduction in fuel consumption can be suppressed.

On the other hand, according to the present embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region L, when the engine speed of the internal combustion engine 1 is low, the in-cylinder gas of the internal combustion engine 1 is reduced. Disturbance hardly occurs and resistance to combustion deterioration factors is low. Further, when the operating state of the internal combustion engine 1 shifts to the high load region side H from this case, the operating state of the internal combustion engine 1 becomes a state in which knocking at a low rotation and high load is likely to occur immediately after the transition. A greater amount of external EGR gas is required to suppress. Therefore, in this case, in order to maximize the resistance against the combustion deterioration factor, the retard amount of the opening / closing timing of the intake valve 6 is increased, the opening timing of the intake valve 6 is delayed and the intake valve 6 is opened. By making the valve closing timing as close as possible to closing near the bottom dead center, it is possible to further enhance the resistance against the cause of combustion deterioration.

  Next, a control routine when the operating state of the internal combustion engine 1 according to this embodiment shifts from the low load region side L to the high load region side H will be described. The control routine when the operating state of the internal combustion engine 1 according to the present embodiment shifts from the low load region side L to the high load region side H is the same as that in FIG. 8 of the first embodiment. In the following description, only step S104 different from the first embodiment will be described.

  In step S104, the ECU 15 controls the predetermined region mode when the operating state of the internal combustion engine 1 is the predetermined region P.

  The predetermined region mode in the present embodiment uses the variable valve timing mechanism 9 of the intake valve 6 to set the valve timing of the intake valve 6 as compared with the case where the opening / closing timing of the intake valve 6 is in the low load region side L. The timing is retarded and the amount of retardation increases as the engine speed of the internal combustion engine 1 decreases. Here, the retard amount of the opening / closing timing of the intake valve 6 is a correlation between the engine speed of the internal combustion engine 1 and the retard amount of the opening / closing timing of the intake valve 6 as shown in FIG. It can be obtained by incorporating the engine speed of the internal combustion engine 1 into a map representing the relationship. At the same time, the external EGR valve 32 is controlled to the open side so that the operation state of the internal combustion engine 1 is higher than that in the case where the operation state of the internal combustion engine 1 is on the low load region side L. The introduction of the required amount of external EGR gas required when it is on the load region side H is started. In the predetermined region mode, the valve operating angle of the intake valve 6 is maintained at a small operating angle.

  As described above, according to this embodiment, when the engine speed of the internal combustion engine 1 is high, it is possible to suppress a slight decrease in fuel consumption, and to maintain a state in which the resistance to the combustion deterioration factor for introducing the external EGR gas is enhanced. be able to.

<Example 3>
Next, Example 3 will be described. Here, a configuration different from the above-described embodiment will be described, and description of the same configuration will be omitted.

  When the operating state of the internal combustion engine 1 is in the low load region side L, if possible, the closing timing of the intake valve 6 should be closed earlier than the bottom dead center to reduce pump loss and improve fuel efficiency. . However, in the first embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the valve opening timing of the intake valve 6 is delayed to increase the resistance against combustion deterioration factors. In addition, the closing timing of the intake valve 6 is closed near the bottom dead center. For this reason, in Example 1, pump loss cannot be reduced and the effect of improving fuel consumption cannot be obtained uniformly.

  Here, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the required amount of external EGR gas required on the high load region side H that shifts from the predetermined region P varies. To do. And when the request | requirement amount of external EGR gas is small, the increase amount of external EGR gas which is a combustion deterioration factor is small, and tolerance with respect to a combustion deterioration factor may be comparatively low. For this reason, in this case, the retard amount of the opening / closing timing of the intake valve 6 for enhancing the resistance against the deterioration factor of combustion is decreased, and the closing timing of the intake valve 6 is set to the closing side as soon as possible, whereby the pump I want to reduce the loss and suppress the reduction in fuel consumption as much as possible.

On the other hand, when the required amount of external EGR gas is large, the amount of increase in external EGR gas, which is a cause of combustion deterioration, is large, and it is preferable that resistance to the deterioration factor of combustion is as high as possible. Therefore, in this case, in order to maximize the resistance to the combustion deterioration factor, the retard amount of the opening / closing timing of the intake valve 6 is delayed, the opening timing of the intake valve 6 is delayed, and the closing timing of the intake valve 6 is closed. I want to increase as close as possible to close near the bottom dead center.

  Therefore, in this embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the intake valve valve timing variable mechanism 9 is used to change the valve timing of the intake valve 6 to the intake valve 6. The amount of delay of the opening / closing timing of the intake valve 6 when the opening / closing timing of the engine is set to be delayed more than when the operating state of the internal combustion engine 1 is in the low load region L is further increased from the predetermined region P to the higher load direction. When the required amount of external EGR gas required on the high load region side H when shifting to is increased, it is increased.

  According to this embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P within the low load region L, when the required amount of external EGR gas is small, the amount of increase in external EGR gas that is a cause of deterioration in combustion. The resistance to combustion deterioration factors may be relatively low. For this reason, in this case, the retard amount of the opening / closing timing of the intake valve 6 for enhancing the resistance against the deterioration factor of combustion is decreased, and the closing timing of the intake valve 6 is set to the closing side as soon as possible, whereby the pump Loss can be reduced and reduction in fuel consumption can be suppressed.

  On the other hand, according to the present embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P within the low load region L, when the required amount of external EGR gas is large, the external EGR gas that is a cause of combustion deterioration The amount of increase is large, and it is better that the resistance to combustion deterioration factors is as high as possible. Therefore, in this case, in order to maximize the resistance against the combustion deterioration factor, the retard amount of the opening / closing timing of the intake valve 6 is increased, the opening timing of the intake valve 6 is delayed and the intake valve 6 is opened. By making the valve closing timing as close as possible to closing near the bottom dead center, it is possible to further enhance the resistance against the cause of combustion deterioration.

  Next, a control routine when the operating state of the internal combustion engine 1 according to this embodiment shifts from the low load region side L to the high load region side H will be described. The control routine when the operating state of the internal combustion engine 1 according to the present embodiment shifts from the low load region side L to the high load region side H is the same as that in FIG. 8 of the first embodiment. In the following description, only step S104 different from the first embodiment will be described.

  In step S104, the ECU 15 controls the predetermined region mode when the operating state of the internal combustion engine 1 is the predetermined region P.

  The predetermined region mode in the present embodiment uses the variable valve timing mechanism 9 of the intake valve 6 to set the valve timing of the intake valve 6 as compared with the case where the opening / closing timing of the intake valve 6 is in the low load region side L. The timing is set so as to increase as the required amount of external EGR gas required on the high load region side H increases when the retarded amount and the amount of retardation shift from the predetermined region P to the higher load direction. Here, the retard amount of the opening / closing timing of the intake valve 6 is a correlation between the required amount of external EGR gas and the retard amount of the opening / closing timing of the intake valve 6 as shown in FIG. Can be obtained by taking the required amount of the external EGR gas into the map representing. At the same time, the external EGR valve 32 is controlled to open, and the required amount of external EGR gas is started to be introduced. In the predetermined region mode, the valve operating angle of the intake valve 6 is maintained at a small operating angle.

  As described above, according to the present embodiment, when the required amount of external EGR gas is small, it is possible to suppress a slight decrease in fuel consumption.

<Example 4>
Next, Example 4 will be described. Here, a configuration different from the above-described embodiment will be described, and description of the same configuration will be omitted.

  FIG. 11 is a diagram illustrating a schematic configuration of an internal combustion engine to which the control device for an internal combustion engine according to the present embodiment is applied.

  In the present embodiment, the external EGR device 30 includes a bypass passage 34 that bypasses the external EGR cooler 33 by the external EGR gas that circulates in the external EGR device 30, and a bypass valve 35 that opens and closes the bypass passage 34. Yes.

  The bypass passage 34 is connected to the external EGR passage 31 directly upstream and downstream of the external EGR cooler 33, and can bypass the external EGR cooler 33 by the external EGR gas.

  The bypass valve 35 is disposed in the bypass passage 34, opens to allow the external EGR gas to flow through the bypass passage 34, and closes to prevent the flow of the external EGR gas in the bypass passage 34. The ECU 15 can electrically control the bypass valve 35 based on output signals from various sensors.

  By the way, when the operating state of the internal combustion engine 1 is in the low load region side L, if possible, the closing timing of the intake valve is closed earlier than the bottom dead center to reduce pump loss and improve fuel efficiency. Want to. However, in the first embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the valve opening timing of the intake valve 6 is delayed to increase the resistance against combustion deterioration factors. In addition, the closing timing of the intake valve 6 is closed near the bottom dead center. For this reason, in Example 1, pump loss cannot be reduced and the effect of improving fuel consumption cannot be obtained uniformly.

  Here, if the temperature of the external EGR gas recirculated to the internal combustion engine 1 is high, the in-cylinder temperature of the internal combustion engine 1 increases because the heat capacity of the high-temperature external EGR gas is small. As a result, the in-cylinder temperature of the internal combustion engine 1 rises, so that combustion is improved and resistance to combustion deterioration factors is increased. For this reason, if the temperature of the external EGR gas is high, it is necessary to delay the opening timing of the intake valve 6 and close the closing timing of the intake valve 6 in the vicinity of the bottom dead center in order to increase the resistance to the combustion deterioration factor. Disappears.

  Therefore, in this embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the external EGR gas is used when the operating state of the internal combustion engine 1 is on the high load region side H. When the introduction starts toward the required amount and the introduced external EGR gas amount reaches a predetermined amount that is a threshold value that requires the temperature of the external EGR gas to be increased so as not to deteriorate the combustion state of the internal combustion engine 1. The bypass valve 35 is opened.

  Here, the predetermined amount means that when an external EGR gas amount larger than that is introduced, the introduced external EGR gas amount does not deteriorate the combustion state of the internal combustion engine 1, so that the temperature of the external EGR gas needs to be raised. This is the amount of external EGR gas that is the threshold value that occurs.

  According to the present embodiment, when the introduced external EGR gas amount reaches a predetermined amount, the bypass valve 35 is opened. According to this, the external EGR gas bypasses the external EGR cooler 33, and the external EGR gas passes through the bypass passage 34. Thus, the external EGR gas that bypasses the external EGR cooler 33 is not cooled by the EGR cooler 33 and thus has a high temperature. Therefore, high temperature external EGR gas is introduced into the internal combustion engine 1. When the high-temperature external EGR gas is introduced, the in-cylinder temperature of the internal combustion engine 1 increases because the heat capacity of the high-temperature external EGR gas is small. As a result, the in-cylinder temperature of the internal combustion engine 1 rises, so that combustion is improved and resistance to combustion deterioration factors is increased.

  FIG. 12 shows a case where the temperature of the external EGR gas through which the external EGR gas passes through the external EGR cooler 33 is low, and a case where the external EGR gas through which the external EGR gas passes through the bypass passage 34 is high as in this embodiment. It is a figure which shows the external EGR gas amount until combustion fluctuation | variation becomes large. The broken line in FIG. 12 indicates the characteristics when the temperature of the external EGR gas through which the external EGR gas passes through the external EGR cooler 33 is low, and the solid line indicates the case when the external EGR gas through which the external EGR gas passes through the bypass passage 34 is hot. Show the characteristics.

  As shown in FIG. 12, when the external EGR gas is high in temperature, combustion is unlikely to deteriorate even when the amount of external EGR gas, which is a cause of combustion deterioration, is significantly increased compared to when the external EGR gas is low in temperature. In the present embodiment, when the external EGR gas amount reaches a predetermined amount, the characteristic changes due to the transition from the broken line A position to the solid B position, and the resistance to the combustion deterioration factor increases. Even if the amount of EGR gas is increased, combustion does not deteriorate, and a large amount of external EGR gas close to the required amount can be introduced.

  Since a large amount of external EGR gas close to the required amount can be introduced as described above, in this embodiment, when the operating state of the internal combustion engine 1 is in the predetermined region P in the low load region side L, the external EGR gas is The introduction starts toward the required amount required when the operating state of the engine 1 is on the high load region side H.

  Then, in the present embodiment, the external EGR gas is increased when the operating state of the internal combustion engine 1 is in the predetermined region P, that is, before the operating state of the internal combustion engine 1 is shifted to the high load region side H. Therefore, when the operating state of the internal combustion engine 1 actually shifts from the predetermined region P to the high load region side H, an amount close to the required amount required when the operating state of the internal combustion engine 1 is on the high load region side H. The external EGR gas is already introduced. Therefore, when the operating state of the internal combustion engine 1 shifts to the high load region side H, that is, when the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle, the required amount and the actual external EGR gas amount There is almost no deviation. Therefore, immediately after the operating state of the internal combustion engine 1 shifts to the high load region side H, that is, immediately after the valve operating angle of the intake valve is switched from the small operating angle to the large operating angle, there is no shortage of external EGR gas. Therefore, sufficient external EGR gas is introduced, the heat capacity of the in-cylinder gas of the internal combustion engine 1 is increased, the combustion temperature is lowered, and the cooling loss is lowered. For this reason, a fuel consumption can be improved because cooling loss falls. In addition, since there is no reflux delay until the required amount of external EGR gas is supplied to the internal combustion engine 1 when the operating state of the internal combustion engine 1 is on the high load region side H, control of the intake air amount can be performed. This also makes it possible to improve fuel consumption. In addition, there is no concern about torque shock due to the lack of external EGR gas.

  Here, in the present embodiment, when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the valve timing of the intake valve 6 is set to the closing timing of the intake valve 6 from the bottom dead center. It is maintained at the timing of early closing. For this reason, even when the operating state of the internal combustion engine 1 shifts to the predetermined region P in the low load region side L, the closing timing of the intake valve 6 is set earlier than the bottom dead center, Pump loss can be reduced and fuel consumption can be improved.

  Next, a control routine when the operating state of the internal combustion engine 1 according to this embodiment shifts from the low load region side L to the high load region side H will be described. FIG. 13 is a flowchart showing a control routine when the operating state of the internal combustion engine 1 according to this embodiment shifts from the low load region side L to the high load region side H. This routine is repeatedly executed every predetermined time. In this routine, steps S101 to S106 (no S104) are the same as those in the control routine of FIG. 8, and thus description thereof will be omitted, and steps S201 to S203 will be described.

If it is determined in step S103 that the operating state of the internal combustion engine 1 has shifted to the predetermined region P, the process proceeds to step S201. If it is determined in step S103 that the operating state of the internal combustion engine 1 does not shift to the predetermined region P, the process returns to step S102.

  In step S201, the ECU 15 controls the second predetermined region mode when the operating state of the internal combustion engine 1 is the predetermined region P.

  In the second predetermined region mode, the external EGR valve 32 is controlled to the open side so that the amount of external EGR gas is larger than that in the case where the operation state of the internal combustion engine 1 is on the low load region side L, and the operation of the internal combustion engine 1 is performed. The introduction of the required amount of external EGR gas required when the state is on the high load region side H is started. In the second predetermined region mode, the valve operating angle of the intake valve 6 is maintained at a small operating angle, and the valve timing of the intake valve 6 is that the valve closing timing of the intake valve 6 is closed earlier than the bottom dead center. Stays in timing.

  In step S202, the ECU 15 determines whether or not the introduced external EGR gas amount has reached a predetermined amount.

  Specifically, the operating state of the internal combustion engine 1 is applied to a map (not shown) obtained beforehand through experiments or the like, and it is determined whether the amount of introduced external EGR gas has reached a predetermined amount.

  When it is determined positive in step S202 that the amount of external EGR gas introduced has reached a predetermined amount, the process proceeds to step S203. When it is determined negative in step S202 that the amount of external EGR gas introduced does not reach the predetermined amount, the process returns to step S201.

  In step S203, the ECU 15 opens the bypass valve 35.

  Opening the bypass valve 35 in this manner causes the external EGR gas to bypass the external EGR cooler 33 in the external EGR device 30, and the external EGR gas flows through the bypass passage 34, and the temperature of the external EGR gas becomes high. Become.

  After step S203, the process proceeds to step S105.

  By executing the above control routine, when the valve operating angle of the intake valve 6 is switched from the small operating angle to the large operating angle, the amount of external EGR gas can be smoothly introduced without abruptly changing the amount of external EGR gas, It is possible to improve the fuel consumption before and after switching the valve operating angle of the intake valve 6 to a large operating angle.

  The control device for an internal combustion engine according to the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the gist of the present invention.

1 is a diagram illustrating a schematic configuration of an internal combustion engine according to a first embodiment. It is the schematic which shows the control state according to the driving | running state of the conventional internal combustion engine. It is a figure which shows the time change of the external EGR gas amount at the time of switching the valve working angle of the conventional intake valve from a small working angle to a large working angle. 1 is a schematic diagram illustrating a control state according to an operating state of an internal combustion engine 1 according to a first embodiment. It is a figure explaining a mode that the valve timing of an intake valve is changed when the driving | running state of the internal combustion engine which concerns on Example 1 transfers to the predetermined area | region within the low load area | region side. It is a figure which shows the amount of external EGR gas until combustion fluctuation | variation becomes large when the opening / closing timing of an intake valve differs. It is a figure which shows the time change of the external EGR gas amount at the time of switching the valve working angle of the intake valve which concerns on Example 1 from a small working angle to a large working angle. 3 is a flowchart illustrating a control routine when the operating state of the internal combustion engine according to the first embodiment shifts from a low load region side to a high load region side. 7 is a map showing a correlation between an engine speed of an internal combustion engine according to a second embodiment and a retard amount of the opening / closing timing of the intake valve. 10 is a map showing a correlation between a required amount of external EGR gas according to a third embodiment and a retard amount of the opening / closing timing of the intake valve. FIG. 6 is a diagram illustrating a schematic configuration of an internal combustion engine according to a fourth embodiment. It is a figure which shows the amount of external EGR gas until combustion fluctuation | variation becomes large when the temperature of external EGR gas differs. 12 is a flowchart illustrating a control routine when an operating state of an internal combustion engine according to a fourth embodiment shifts from a low load region side to a high load region side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder head 3 Combustion chamber 4 Intake port 5 Exhaust port 6 Intake valve 7 Exhaust valve 8 Intake valve valve working angle variable mechanism 9 Intake valve valve timing variable mechanism 10 Spark plug 11 Intake pipe 12 Exhaust pipe 13 Fuel injection valve 14 Air flow meter 15 ECU
16 Water temperature sensor 17 Crank position sensor 30 External EGR device 31 External EGR passage 32 External EGR valve 33 External EGR cooler 34 Bypass passage 35 Bypass valve

Claims (7)

An intake valve valve operating angle variable mechanism capable of switching the valve operating angle of the intake valve in at least two stages;
An intake valve valve timing variable mechanism capable of changing the valve timing of the intake valve;
An external EGR device that takes in a part of the exhaust gas from the exhaust passage of the internal combustion engine as an external EGR gas and recirculates the external EGR gas to the intake passage of the internal combustion engine;
With
When the operating state of the internal combustion engine is on the low load region side, the valve operating angle of the intake valve is set to a small operating angle, and the valve timing of the intake valve is set to the closing timing of the intake valve from the bottom dead center. As soon as possible the timing of early closing,
When the operating state of the internal combustion engine is on the high load region side, the valve operating angle of the intake valve is set to a large operating angle and the operating state of the internal combustion engine is on the low load region side. A control device for an internal combustion engine that recirculates more than the case,
When the operating state of the internal combustion engine shifts to a predetermined region within the low load region side and before the high load region side, the valve timing of the intake valve is determined according to the opening / closing timing of the intake valve. At a timing that is retarded from the case of being on the low load region side, introduction of the external EGR gas toward the required amount required when the operating state of the internal combustion engine is on the high load region side is started. A control device for an internal combustion engine.   When the operating state of the internal combustion engine shifts to a predetermined region before the high load region within the low load region side, the valve timing of the intake valve is determined based on the valve opening timing of the intake valve. Is delayed later than when the engine is on the low load region side, and the closing timing of the intake valve is set to close near the bottom dead center later than when the operating state of the internal combustion engine is on the low load region side. The control apparatus for an internal combustion engine according to claim 1.   When the operating state of the internal combustion engine shifts to a predetermined region within the low load region side and before the high load region side, the valve timing of the intake valve is determined according to the opening / closing timing of the intake valve. The retard amount of the opening / closing timing of the intake valve when the timing is retarded from that in the low load region side is changed according to the engine speed of the internal combustion engine. Item 2. A control device for an internal combustion engine according to Item 1.   The control apparatus for an internal combustion engine according to claim 3, wherein the retard amount increases as the engine speed of the internal combustion engine decreases.   When the operating state of the internal combustion engine shifts to a predetermined region within the low load region side and before the high load region side, the valve timing of the intake valve is determined according to the opening / closing timing of the intake valve. The retard amount of the opening / closing timing of the intake valve when the timing is retarded from that in the low load region side is changed according to the required amount of external EGR gas. Item 2. A control device for an internal combustion engine according to Item 1.   6. The control apparatus for an internal combustion engine according to claim 5, wherein the retard amount increases as the required amount of external EGR gas increases. An intake valve valve operating angle variable mechanism capable of switching the valve operating angle of the intake valve in at least two stages;
An intake valve valve timing variable mechanism capable of changing the valve timing of the intake valve;
An external EGR device that takes in a part of the exhaust gas from the exhaust passage of the internal combustion engine as an external EGR gas and recirculates the external EGR gas to the intake passage of the internal combustion engine;
With
When the operating state of the internal combustion engine is on the low load region side, the valve operating angle of the intake valve is set to a small operating angle, and the valve timing of the intake valve is set to the closing timing of the intake valve from the bottom dead center. As soon as possible the timing of early closing,
When the operating state of the internal combustion engine is on the high load region side, the valve operating angle of the intake valve is set to a large operating angle and the operating state of the internal combustion engine is on the low load region side. A control device for an internal combustion engine that recirculates more than the case,
The external EGR device includes an EGR cooler that cools the external EGR gas that circulates in the external EGR device, a bypass passage that bypasses the EGR cooler to the external EGR gas that circulates in the external EGR device, and the bypass A bypass valve for opening and closing the passage,
When the operating state of the internal combustion engine is shifted to a predetermined region within the low load region side and before the high load region side, the external EGR gas is used when the operating state of the internal combustion engine is on the high load region side. The introduction starts toward the required amount, and the amount of the introduced external EGR gas reaches a predetermined amount that becomes a threshold value that requires the temperature of the external EGR gas to be raised so as not to deteriorate the combustion state of the internal combustion engine. Then, the control device for the internal combustion engine, wherein the bypass valve is opened.

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