JP4561652B2 - Control device for internal combustion engine - Google Patents

Description

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

  2. Description of the Related Art An internal combustion engine having an EGR (exhaust gas recirculation) device that recirculates part of exhaust gas to an intake system in order to improve exhaust characteristics is well known. The EGR device includes an EGR passage that communicates an exhaust system and an intake system of an internal combustion engine, and an EGR valve that adjusts the flow area of the EGR passage. Then, by operating the opening degree of the EGR valve, the exhaust amount (EGR amount) recirculated to the intake system via the EGR passage is controlled. When a part of the exhaust gas is recirculated to the intake system by the EGR device, the balance between the amount of air sucked through the intake pipe and the EGR amount (that is, the EGR rate) is adjusted, thereby improving the exhaust characteristics.

  In the control of the EGR amount, a state amount indicating the operating state of the internal combustion engine is detected, and feedback control is performed so that the detected actual state amount becomes the target state amount. For example, an intake air amount, exhaust O2 concentration, or the like is used as a state quantity indicating an operation state. At this time, the target values of these state quantities are set according to parameters correlated with the load of the internal combustion engine, such as required torque and fuel injection quantity.

  By the way, in the fuel injection valve, operation variation may occur, and when the operation variation occurs, the fuel injection amount varies. Here, when the target value of the state quantity is set according to the fuel injection quantity, the target value of the state quantity deviates from an accurate value due to variations in the fuel injection quantity. If the target value of the state quantity deviates from an accurate value, an error occurs in the operation amount of the EGR valve controlled based on the state quantity. Therefore, the control accuracy of the EGR amount is lowered, and the exhaust emission is deteriorated. The magnitude of the state quantity deviation with respect to the fuel injection quantity differs depending on which state quantity is used as the control parameter, and if the state quantity deviation is different, the EGR valve operating quantity error is large. Is different.

  Therefore, in Patent Document 1, the EGR amount is controlled using a state quantity that reduces an error in the operation amount of the EGR valve. For example, when the required torque is large, that is, when the fuel injection amount is large, the EGR amount is controlled with the state amount as the exhaust O2 concentration, and in other cases, the EGR amount is controlled with the state amount as the intake air amount. Yes. Thereby, the fall of the control precision of the amount of EGR is suppressed, and the deterioration of exhaust emission is suppressed.

In such a case, for example, when a sensor for detecting the exhaust O2 concentration fails, EGR control using the state quantity as the exhaust O2 concentration cannot be performed, and instead, the EGR control is performed using the state quantity as the intake air amount. Is called. At this time, since the fuel injection amount is large, the control accuracy of the EGR amount using the state amount as the intake air amount is lower than the accuracy of the normal EGR control using the state amount as the exhaust O2 concentration. As a result, PM (particulate matter) and the like in the exhaust gas may increase and exhaust emission may deteriorate.
JP 2005-188392 A

  The main object of the present invention is to provide a control device for an internal combustion engine that can appropriately control the amount of air flowing into the cylinder of the internal combustion engine, and thus can achieve optimization of exhaust emission.

In the first aspect of the invention, an air amount adjusting means (for example, an EGR device) for adjusting the amount of air flowing into the cylinder from the intake system of the internal combustion engine, and an air amount detecting means (air flow) for detecting the air amount of the intake system. Meter) and oxygen concentration detection means (A / F sensor) for detecting the oxygen concentration in the exhaust gas discharged from the internal combustion engine. In addition, as control means for performing air amount control, first control means for performing air amount control using a first control characteristic using the amount of air flowing into the intake system as a parameter, and oxygen concentration in the exhaust gas Second control means for performing air amount control using a second control characteristic as a parameter, and the air amount is selectively used according to the operating region of the internal combustion engine. Execute control. In particular, when the air amount control is performed by either the first or second control means , the control for the non-executed control means of the first or second control means is performed in parallel with the control. Learn the characteristics. Further, when the abnormality relating to the first and second control means is determined, respectively, and it is determined that there is an abnormality relating to one of the first and second control means, the control characteristic learned by the learning means is obtained. The air amount control by the other control means is executed.

  Here, when either the first or second control means is selectively used, the control accuracy of the other control means may be lower than that of the one control means normally used preferentially. Conceivable. At this time, by executing the above learning, it is possible to define an appropriate control characteristic even in the control means that is not normally selected. In this case, the control characteristics after learning can eliminate control variations due to individual differences and changes with time.

  Even if the air amount control of one of the first and second control means cannot be executed, and the other control means is executed as a compensation, the reduction in the accuracy of the air amount control is suppressed. Can do. Therefore, it is possible to appropriately control the amount of air flowing into the cylinder of the internal combustion engine, and thus to achieve optimization of exhaust emission.

Further , the air amount control is executed by selectively using the first or second control means in accordance with the operating region of the internal combustion engine.

The accuracy of the air amount control by the first or second control means varies depending on the operating region of the internal combustion engine. Therefore, it is preferable to switch the control means in accordance with the operating region of the internal combustion engine. By executing the air amount control by the control means suitable for the operation region, the air amount control can be appropriately executed.
Furthermore, it has a means for judging each abnormality regarding the 1st and 2nd control means. Then, when it is determined that either the first or second control means is abnormal, the air amount control is executed using the control characteristics learned by the learning means.
It is considered that the air amount control by the control means in which an abnormality has occurred is not properly executed. Therefore, when one of the control means for executing the air amount control is abnormal, it is desirable that the air amount control by the other control means is executed using the learned control characteristic. Thereby, even if either the 1st or 2nd control means is abnormal, air quantity control can be performed appropriately.

According to the second aspect of the invention, the air amount control by the first control means is executed in the low load region of the internal combustion engine, and the air amount control by the second control means is executed in the other load regions.

  Comparing the air amount control by the first control means (control using the intake air amount as a parameter) and the air amount control by the second control means (control using the exhaust oxygen concentration as a parameter), The first control means has higher control accuracy, and the second control means has higher control accuracy in regions other than the low load region. Therefore, it is preferable that the air amount control is executed by the first control unit in the low load region, and the air amount control is executed by the second control unit in the other load regions.

According to the third aspect of the present invention, when the air amount is controlled by the first control unit, the second control characteristic is learned based on the detection value of the oxygen concentration detection unit, and when the air amount is controlled by the second control unit, the air Learning about the second control characteristic is performed based on the detection value of the amount detection means.

  When the air amount control is executed by the first control means, the exhaust oxygen concentration detected by the oxygen concentration detection means is executed by the second control means instead of the first control means. Corresponds to the exhaust oxygen concentration to be controlled. When learning about the second control characteristic is performed based on the detected exhaust oxygen concentration, the second learning is performed when the air amount control is executed by the second control unit instead of the first control unit. If this control characteristic is used, the air amount control can be appropriately executed.

  Further, when the air amount control is executed by the second control means, the intake air amount detected by the air amount detection means is controlled by the first control means instead of the second control means. When executed, this corresponds to the amount of intake air to be controlled. When learning about the first control characteristic is performed based on the detected intake air amount, the learning is performed when the air amount control is executed by the first control unit instead of the second control unit. If this control characteristic is used, the air amount control can be appropriately executed.

According to a fourth aspect of the present invention, an EGR valve for adjusting the amount of EGR flowing through the EGR passage of the internal combustion engine is provided. Then, air amount control is executed using an EGR valve as the air amount adjusting means. The amount of air can be adjusted by adjusting the EGR amount by adjusting the opening of the EGR valve and adjusting the EGR amount. For this reason, air amount control can be performed by performing EGR amount control by an EGR valve.

According to a fifth aspect of the present invention, there is provided a throttle valve for adjusting the amount of air flowing through the intake passage of the internal combustion engine. Air amount control is executed using a throttle valve as the air amount adjusting means. The amount of air can be adjusted by adjusting the opening of the throttle valve. For this reason, the air amount control can be executed by executing the throttle valve opening control.

The invention described in claim 6 is provided with a variable supercharging device that makes the supercharging state variable. And air quantity control is performed using a variable supercharging device as the air quantity adjusting means. The amount of air can be adjusted by adjusting the supercharging state. For this reason, air quantity control can be performed by performing control of a supercharging state with a variable supercharging device.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the present embodiment, an engine control system is constructed for a diesel engine that is an internal combustion engine. In this control system, an electronic control unit (hereinafter referred to as ECU) is used as a center to control the fuel injection amount. We are going to carry out. First, an overall schematic configuration diagram of the engine control system will be described with reference to FIG.

  In the engine 10 shown in FIG. 1, the intake pipe 11 is provided with a throttle valve 12 whose opening is adjusted by an actuator such as a DC motor, and a throttle opening sensor 13 for detecting the throttle opening. An intake valve 21 and an exhaust valve 22 are respectively provided at the intake port leading to the intake pipe 11 and the exhaust port leading to the exhaust pipe 14, and when the intake valve 21 is opened, a mixed gas of air and EGR gas is discharged into the combustion chamber. The exhaust after combustion is discharged into the exhaust pipe 14 by the opening operation of the exhaust valve 22. An electromagnetically driven fuel injection valve 24 for supplying and supplying fuel is attached to the combustion chamber 23.

  The exhaust pipe 14 is provided with a DPF (diesel particulate filter) 31 for collecting PM in the exhaust. In addition to the DPF 31, an NOx catalyst that purifies NOx in the exhaust, an oxidation catalyst that purifies HC and CO in the exhaust, and the like may be provided as the exhaust purification device. An A / F sensor 32 is provided on the downstream side of the DPF 31 to detect the oxygen concentration (hereinafter referred to as exhaust O2 concentration) using exhaust as a detection target.

  The engine 10 is provided with a turbocharger for supercharging using exhaust power. As a turbocharger, an intake air compressor 33 is provided in the intake pipe 11, and an exhaust turbine 34 is provided in the exhaust pipe 14. In the turbocharger, the exhaust turbine 34 is rotated by the exhaust gas flowing through the exhaust pipe 14, and the rotational force is transmitted to the intake compressor 33. Then, the intake air flowing through the intake pipe 11 is compressed by the intake air compressor 33 and supercharging is performed.

  On the upstream side of the intake compressor 33, an air flow meter 35 for detecting the intake air amount sucked through an air cleaner (not shown) at the most upstream portion of the intake pipe 11 is provided. In addition, this control system is provided with a rotation speed sensor 38 that detects the rotation speed of the engine 10 and an accelerator sensor 39 that detects the amount of depression of the accelerator pedal (accelerator opening) by the driver.

  Further, the engine 10 is provided with an EGR device for recirculating a part of the exhaust gas as EGR gas to the intake system. As an EGR device, an EGR pipe 41 is provided between the intake pipe 11 and the exhaust pipe 14, and the EGR pipe 41 is provided with an EGR valve 42 formed of an electromagnetic valve or the like. By adjusting the opening degree of the EGR valve 42, the exhaust amount (EGR amount) recirculated to the intake system through the EGR pipe 41 is adjusted. That is, the intake air amount sucked into the intake port of the engine 10 is adjusted. The EGR pipe 41 may be provided with an EGR cooler for cooling the EGR gas passing through the pipe.

  The ECU 50 is an electronic control unit that includes a known microcomputer including a CPU, ROM, RAM, EEPROM, and the like. Detection signals of the various sensors described above are sequentially input to the ECU 50. The ECU 50 executes various control programs stored in the ROM, thereby appropriately performing fuel injection control of the fuel injection valve 24 according to the engine operating state. That is, the ECU 50 determines the optimum fuel injection amount and injection timing based on engine operation information such as the engine rotation speed and the accelerator operation amount detected from various sensors, and drives the fuel injection valve 24 by an injection control signal corresponding thereto. To control. Moreover, the function which determines the presence or absence of the failure of the air flow meter 35 or the A / F sensor 32 is provided.

  Further, the ECU 50 performs EGR control for controlling the EGR amount by adjusting the opening of the EGR valve 42 in order to optimally control the balance between the intake air amount sucked into the cylinder and the EGR amount (that is, the EGR rate). . In the present embodiment, “air amount EGR control” for controlling the EGR opening with the intake air amount as a parameter and “O2 concentration EGR control” for controlling the EGR opening with the exhaust O2 concentration as a parameter are selectively executed. To do.

  Here, in the air amount EGR control, a normal air amount map that defines a target value of the intake air amount (hereinafter referred to as a target air amount) using the command injection amount of the fuel injection valve 24 and the engine speed as parameters is used. The amount of air is calculated. Then, EGR feedback control is performed so that the actual intake air amount (hereinafter referred to as the actual air amount) calculated from the detection signal of the air flow meter 35 becomes the target air amount. Similarly, in the O2 concentration EGR control, a target O2 concentration is calculated using a normal O2 concentration map that defines a target value of exhaust O2 concentration (hereinafter referred to as a target O2 concentration) using the command injection amount and the engine speed as parameters. The Then, EGR feedback control is performed so that the actual exhaust O2 concentration (hereinafter referred to as the actual O2 concentration) calculated from the detection signal of the A / F sensor becomes the target O2 concentration. The normal air amount map and the normal O2 concentration map are defined by conformance and the like, and are stored in the ROM in the ECU 50.

  FIG. 2A shows the characteristics of the command injection amount, the target air amount, and the target O2 concentration. According to FIG. 2A, the target O2 concentration is substantially constant in the high injection amount region where the command injection amount is relatively large. Corresponding to the fact that the target O2 concentration is substantially constant, the target air amount is increased as the command injection amount increases.

  On the other hand, in the low injection amount region where the command injection amount is relatively small, if the target O2 concentration is kept constant, the target air amount must be reduced accordingly, and if the intake air amount is reduced too much at that time, There is a risk that the amount of air is insufficient and the combustion state deteriorates. For this reason, the target air amount is substantially constant at a predetermined value with respect to the decrease in the command injection amount. Corresponding to the fact that the target air amount is substantially constant, the target O2 concentration is increased as the command injection amount decreases.

  Here, in the fuel injection valve 24, operation variations due to individual differences and changes with time occur, and the fuel injection amount from the fuel injection valve 24 may vary. In this case, according to the characteristic shown in FIG. 2A, when the injection amount varies, the intake air amount varies in the high injection amount region, and the injection amount variation occurs in the low injection amount region. Variation in density occurs. Therefore, the exhaust emission may vary due to the injection amount variation. In addition, since variation in injection amount cannot be detected, variation in intake air amount and variation in exhaust O2 concentration are problematic.

  FIG. 2B shows the relationship between the command injection amount and the variation in exhaust emission. In FIG. 2B, regarding the O2 concentration EGR control, since the target O2 concentration is substantially constant in the high injection amount region, the exhaust emission does not vary even if the injection amount varies. On the other hand, since the target O2 concentration changes in the low injection amount region, exhaust emission varies when the injection amount variation occurs. With regard to the air amount EGR control, the target air amount is almost constant in the low injection amount region, so that the exhaust emission does not vary even if the injection amount varies, but the target air amount changes in the high injection amount region. When the injection amount varies, the exhaust emission varies.

  Therefore, air amount EGR control is executed in the low injection amount region, and O2 concentration EGR control is executed in the middle and high injection amount regions. Specifically, the command injection amount at the point where the characteristic of the exhaust emission variation when the air amount EGR control is executed intersects the characteristic of the exhaust emission variation when the O2 concentration EGR control is executed is the injection amount A. If the injection amount is less than the injection amount A, the air amount EGR control is executed, and if the command injection amount is the injection amount A or more, the O2 concentration EGR control is executed. As described above, by selectively using either the air amount EGR control or the O2 concentration EGR control according to the magnitude of the command injection amount, it is possible to suppress a decrease in the accuracy of the EGR control.

  For example, when a trouble such as a failure occurs in the air flow meter 35, the air amount EGR control cannot be executed properly. Therefore, the O2 concentration EGR control is executed not only in the middle and high injection amount regions but also in the low injection amount region. . However, the accuracy of O2 concentration EGR control is lower in the low injection amount region than in the middle and high injection amount regions. In addition, when trouble such as a failure occurs in the A / F sensor 32 and the O2 concentration EGR control cannot be executed properly, the air amount EGR control is performed not only in the low injection amount region but also in the middle and high injection amount regions. Execute. However, the accuracy of the air amount EGR control is lower in the middle and high injection regions than in the low injection amount region. When the accuracy of the EGR control is lowered, fuel consumption may be deteriorated, or exhaust emission may vary and PM and NOx in the exhaust may increase. Incidentally, when PM in the exhaust gas increases, PM combustion removal (DPF regeneration processing) is frequently performed. For this reason, there is a possibility that inconvenience such as deterioration of fuel consumption and burning of the DPF 31 may occur.

  Therefore, in the present embodiment, a learning map in which a learning value can be written is created in addition to a normal map (normal air amount map, normal O2 concentration map) set in advance. The learning map is created corresponding to each of the air amount EGR control and the O2 concentration EGR control, and if a problem occurs in either the air amount EGR control or the O2 concentration EGR control that is being executed, a problem occurs. Used for EGR control that has not been performed.

  Specifically, the learning air amount map defines the target air amount using the fuel injection amount and the engine speed as parameters, as in the normal air amount map described above. The learning O2 concentration map includes the fuel injection amount and the fuel injection amount. The target O2 concentration is defined using the engine speed as a parameter. The learning air amount map and the learning O2 concentration map are stored in an EEPROM or the like in the ECU 50, and are appropriately written and read.

  When the air amount EGR control is executed in the low injection amount region, the actual O2 concentration is detected by the A / F sensor 32. At this time, the detected value of the actual O2 concentration corresponds to the target O2 concentration to be controlled when the O2 concentration EGR control is executed instead of the air amount EGR control. Therefore, by learning the learning O2 concentration map based on the actual O2 concentration, the learning O2 concentration map can be made to correspond to the injection amount variation.

  On the other hand, when the O2 concentration EGR control is executed in the high injection amount region, the air flow meter 35 detects the actual air amount. At this time, the detected value of the actual air amount corresponds to the target air amount to be controlled when the air amount EGR control is executed instead of the O2 concentration EGR control. Therefore, by learning the learning air amount map based on the actual air amount, the learning O2 concentration map can be made to correspond to the injection amount variation.

  FIG. 3 is a flowchart showing the EGR control process. This process is repeatedly executed by the ECU 50 at a predetermined time period. In the following description, normal EGR control when the air flow meter 35 and the A / F sensor 32 are normal will be described first, and then EGR when an abnormality occurs in the air flow meter and the A / F sensor 32 is described. Control will be described.

  In FIG. 3, in step S101, it is determined whether or not EGR control is being executed. In step S102, it is determined whether or not the command injection amount is less than the injection amount A. Here, for example, if the command fuel injection amount during full load operation of the engine 10 is 50 to 60 mm 3 / st, the injection amount A is set to 10 mm 3 / st. If the command injection amount is less than the injection amount A, that is, if it is in the low injection amount region, the process proceeds to step S103.

  In step S103, it is determined whether or not the intake air amount is normally detected by the air flow meter 35. At this time, the process for determining whether or not the air flow meter 35 is normal is performed by a separate process (not shown). For example, when the opening degree of the throttle valve 12 is adjusted, the air flow meter 35 follows the change in the opening degree. If the detected value does not change, it is determined that the air flow meter 35 is not normal. If the air flow meter 35 is normal, the process proceeds to step S104.

  In step S104, normal air amount EGR control is executed. Here, the target air amount is calculated using the normal air amount map, and the actual air amount is calculated from the detection signal of the air flow meter 35. Then, the duty ratio of EGR control is calculated based on the air amount deviation between the target air amount and the actual air amount, and the opening degree of the EGR valve 42 is controlled by the control duty ratio. In this way, normal EGR feedback control is performed.

  In step S105, learning O2 concentration map is learned. Specifically, as shown in FIG. 4A, the actual O2 concentration is calculated from the detection signal of the A / F sensor 32 in step S201. That is, the actual O2 concentration in a state where the air amount EGR control is being executed is calculated. In step S202, the actual O2 concentration annealing process is performed, and the value after the annealing process is set as a learning value to be updated this time. In step S203, the learning O2 concentration map is updated. By updating the learning map with the values after annealing, it is possible to obtain a learning map that is not affected by noise.

  If NO in step S102, that is, if the injection range is the middle or high injection amount, the process proceeds to step S110, where it is determined whether the exhaust gas O2 concentration is normally detected by the A / F sensor 32 or not. At this time, the determination process of whether the A / F sensor 32 is normal is performed by a separate process (not shown). For example, when the command injection amount is changed or the opening degree of the throttle valve 12 is adjusted, If the detection value of the A / F sensor does not change following this change, it is determined that the A / F sensor 32 is not normal. If the A / F sensor 32 is normal, the process proceeds to step S111.

  In step S111, normal O2 concentration EGR control is executed. Here, the target O2 concentration is calculated using the normal O2 concentration map, and the actual O2 concentration is calculated by the A / F sensor 32. Then, the duty ratio of EGR control is calculated based on the O2 concentration deviation between the target O2 concentration and the actual O2 concentration, and the opening degree of the EGR valve 42 is controlled by the control duty ratio. In this way, normal EGR feedback control is performed.

  Next, in step S112, learning of the learning air amount map is performed. Specifically, as shown in FIG. 4B, the actual air amount is calculated from the detection signal of the air flow meter 35 in step S301. That is, the actual air amount when the O2 concentration EGR control is being executed is calculated. In step S302, the actual air amount is smoothed, and the value after the smoothing is set as a learning value to be updated this time. In step S303, the learning air amount map is updated.

  Next, EGR control when an abnormality occurs in the air flow meter 35 will be described. If step S103 is NO, that is, if an abnormality has occurred in the air flow meter 35, the process proceeds to step S106, where the learning O2 concentration map is read. In the subsequent step S107, the O2 concentration EGR control is executed using the learning O2 concentration map. Here, the target O2 concentration is calculated using the learning O2 concentration map, and EGR feedback control is performed based on the calculated target O2 concentration.

  Next, EGR control when an abnormality occurs in the A / F sensor 32 will be described. If step S110 is NO, that is, if an abnormality has occurred in the A / F sensor 32, the process proceeds to step S113, and the learning air amount map is read. In the following step S114, air amount EGR control is executed using the learning air amount map. Here, the target air amount is calculated using the learning air amount map, and EGR feedback control is performed on the calculated target air amount.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

  The intake air amount EGR control or the O2 concentration EGR control is selectively used according to the operation region of the engine 10 to execute the EGR control. Thereby, EGR control can be appropriately executed in any operation region. Therefore, it is possible to appropriately control the amount of air flowing into the cylinder of the engine 10 and thus to achieve proper exhaust emission.

  The learning O2 concentration map is learned when the intake air amount EGR control is executed, and the learning air amount map is learned when the O2 concentration EGR control is executed. By executing the O2 concentration EGR control using the learning O2 concentration map instead of the intake air amount EGR control in the low injection amount region, the O2 concentration EGR control can be appropriately executed even in the low injection amount region. In addition, the air amount EGR control is appropriately executed even in the middle and high injection regions by executing the air amount EGR control using the learning air amount map instead of the O2 concentration EGR control in the middle and high injection amount regions. be able to.

  When it is determined that the air flow meter 35 is abnormal, the O2 concentration EGR control is executed using the learning O2 concentration map in the low injection amount region, and when it is determined that the A / F sensor 32 is abnormal, In the high injection amount region, the air amount EGR control is executed using the learning air amount map. Thereby, even if either the air flow meter 35 or the A / F sensor 32 is abnormal, the EGR control can be appropriately executed.

  In the above embodiment, in the air amount EGR control and the O2 concentration EGR control, a map (normal air amount map and normal O2 concentration map) defined in advance by adaptation or the like and a map (learning air amount map and Two types of maps (learning O2 concentration map) were prepared. Of these, only the former map may be prepared, and learning may be performed on the map.

  In the above embodiment, the abnormality determination for the air flow meter 35 and the A / F sensor 32 is performed as the abnormality determination for each of the air amount EGR control and the O2 concentration EGR control. However, the present invention is not limited to this. For example, you may perform abnormality determination about EGR control, such as abnormality determination about the learning process of a learning map.

  In the above embodiment, the intake air amount is controlled by adjusting the opening of the EGR valve 42. However, the intake air amount may be controlled by adjusting the opening of the throttle valve 12.

  Further, as the turbocharger, a variable nozzle turbo (VNT) having a variable turbine capacity can be used. In such a configuration, the blade angle of the exhaust turbine 34 can be adjusted, and the supercharging state can be adjusted by changing the blade angle. For this reason, the amount of intake air can be controlled.

It is a block diagram which shows the outline of the engine control system in this Embodiment. It is a figure which shows the characteristic of intake air amount and exhaust gas O2 density | concentration. It is a flowchart which shows an EGR control process. It is a flowchart which shows a learning process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Throttle valve, 23 ... Combustion chamber, 32 ... A / F sensor, 33 ... Intake compressor, 34 ... Exhaust turbine, 35 ... Air flow meter, 41 ... EGR piping, 42 ... EGR valve, 50 ... 1st Control means, second control means, ECU as learning means.

Claims (6)

An air amount adjusting means for adjusting the amount of air flowing into the cylinder from the intake system of the internal combustion engine;
An air amount detecting means for detecting the air amount of the intake system;
Oxygen concentration detection means for detecting the oxygen concentration in the exhaust discharged from the internal combustion engine;
First control means for performing air amount control by the air amount adjusting means using a first control characteristic having the air amount detected by the air amount detecting means as a parameter;
Using a second control characteristic using the oxygen concentration detected by the oxygen concentration detection means as a parameter, and a second control means for executing air amount control by the air amount adjustment means,
In the control apparatus for an internal combustion engine, the air amount control is executed by selectively using either the first or the second control means in accordance with an operation region of the internal combustion engine.
When the air amount control is executed by either the first control means or the second control means, the non-executed control of the first or second control means is performed in parallel with the control by the control means. Learning means for learning control characteristics for the means ;
Means for respectively determining an abnormality relating to the first and second control means,
When it is determined that there is an abnormality related to one of the first and second control means, the air amount control by the other control means is executed using the control characteristic learned by the learning means. An internal combustion engine control device.   The air amount control by the first control means is executed in a low load region of the internal combustion engine, and the air amount control by the second control means is executed in other load regions. 2. A control device for an internal combustion engine according to 1.   The learning means learns the second control characteristic based on a detection value of the oxygen concentration detecting means when the air amount is controlled by the first control means, and when the air amount is controlled by the second control means, The control apparatus for an internal combustion engine according to claim 1 or 2, wherein learning about the first control characteristic is performed based on a detection value of an air amount detection means.   An EGR valve for adjusting the amount of EGR flowing through the EGR passage of the internal combustion engine;
  The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the air amount control is executed using the EGR valve as the air amount adjusting means.   A throttle valve for adjusting the amount of air flowing through the intake passage of the internal combustion engine;
  4. The control apparatus for an internal combustion engine according to claim 1, wherein the air amount control is executed by using the throttle valve as the air amount adjusting means.   The variable amount supercharging device which makes a supercharging state variable is provided, The air amount control is performed using the variable type supercharging device as the air amount adjusting means. The control apparatus of the internal combustion engine described in 1.

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