JP2015190397A - Soot emission estimation device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine soot emission estimation device capable of reducing estimation errors in a soot emission by correcting input parameters in light of a deviation occurrence factor of air-fuel ratio information relating to the estimation of a soot emission from within each cylinder.SOLUTION: An internal combustion engine soot emission estimation device comprises an onboard Soot estimation model 40 calculating a soot emission that is a discharge quantity of soot discharged from within each cylinder using parameters including a quantity of intake air, an indicated injection quantity of fuel, and an estimated A/F as input values. An A/F learning control is executed to learn a difference between an actual A/F and the estimated A/F acquired using an air-fuel ratio sensor 28 and to control an internal combustion engine 10 so as to reduce the difference. The estimation model 40 changes the input parameters reflecting in an A/F learned value depending on what a factor of an air fuel ratio deviation corresponds to, among three factors of a deviation of the quantity of intake air, a deviation of the injection quantity of fuel, and the deviations of both quantity of intake air and the injection quantity of fuel.

Description

  The present invention relates to a soot emission estimating device for an internal combustion engine.

  Conventionally, for example, Patent Document 1 discloses a PM accumulation amount estimation device for a diesel engine. This conventional estimation device increases or decreases the PM emission amount according to the increase or decrease in the excess air ratio (corresponding to air-fuel ratio information), and the PM emission amount (basic value) map using the engine speed and the fuel injection amount as input values. The PM deposition amount is estimated using a model having a correction term to be used. Further, in the above estimation device, the learning value (corresponding to the air / fuel ratio learning value) of the error (corresponding to the deviation amount of the air / fuel ratio information) of the actual excess air ratio with respect to the target excess air ratio is reflected in the excess air ratio as the model input. By doing so, the above error is recognized by the model. Thereby, it is possible to estimate the PM emission amount according to the error.

Japanese Patent No. 4622719 JP2011-058487A Japanese Patent No. 4957431

  When the difference between the estimated air-fuel ratio information based on the intake air amount and the command fuel injection amount and the actual air-fuel ratio information (amount of deviation of the air-fuel ratio information) occurs, the difference between the measured value and the actual value of the intake air amount When a deviation occurs, a deviation may occur between the command fuel injection amount and the actual fuel injection amount, or there may be a deviation between both. However, in the method described in Patent Document 1, the determination of the model is performed without determining whether the cause (main cause) of the deviation of the air-fuel ratio information is the deviation of the intake air amount or the deviation of the fuel injection amount. The learning value relating to the deviation amount of the air-fuel ratio information is reflected only on the air-fuel ratio information (excess air ratio) as an input. As a result, when the cause of the deviation amount of the air-fuel ratio information is one of the deviation of the intake air amount and the deviation of the fuel injection amount, the deviation is included in the fuel injection amount and the intake air amount as the model input. It will not be reflected. This becomes an estimation error factor of the model.

  The present invention has been made to solve the above-described problems, and corrects the input parameters by taking into account the factors that cause the deviation of the air-fuel ratio information related to the estimation of the soot discharge amount from the cylinder. An object of the present invention is to provide a soot emission estimation device for an internal combustion engine that can reduce an estimation error of the emission amount.

A first invention is a soot emission estimating device for an internal combustion engine,
A fuel injection valve for supplying fuel to the internal combustion engine;
An air amount acquisition means for acquiring an intake air amount using an air flow meter disposed in the intake passage;
Real air-fuel ratio acquisition means for acquiring real air-fuel ratio information using an air-fuel ratio sensor disposed in the exhaust passage;
Estimated air-fuel ratio calculating means for calculating estimated air-fuel ratio information based on an intake air amount and a command fuel injection amount of the fuel injection valve;
Learning the difference between the actual air-fuel ratio information and the estimated air-fuel ratio information, and air-fuel ratio learning control means for controlling the internal combustion engine so that the difference becomes smaller;
Soot calculation means for calculating a soot discharge amount that is a discharge amount of soot discharged from the cylinder, using parameters including the intake air amount, command fuel injection amount, and estimated air-fuel ratio information as input values;
With
The soot calculating means includes
The command fuel injection amount is equal to or greater than a predetermined value, and the current operation region is an operation region specified using the EGR rate and the intake air amount, and the difference between the measured value of the intake air amount and the actual value is relative The intake air amount corrected using the air-fuel ratio learning value based on the learning of the difference by the air-fuel ratio learning control means is used as an input value for calculating the soot discharge amount. ,
The command fuel injection amount is less than the predetermined value, and the current operation region is an operation region specified using the EGR rate and the intake air amount, and the difference between the measured value of the intake air amount and the actual value is relative If the command fuel injection amount corrected using the air-fuel ratio learning value is used as an input value for calculating the soot discharge amount,
When the command fuel injection amount is less than the predetermined value and the current operation region is in the first operation region, or the command fuel injection amount is greater than or equal to the predetermined value and the current operation region is the second operation region. When in the operating region, the estimated air-fuel ratio information corrected using the air-fuel ratio learning value is used as an input value for calculating the soot discharge amount.

  According to the first aspect of the invention, the causes of the air-fuel ratio deviation are classified into three, namely the intake air quantity deviation, the fuel injection quantity deviation, and both the intake air quantity and fuel injection quantity deviation, and The input parameter that reflects the air-fuel ratio learning value is changed according to which of these three factors cause the deviation. More specifically, the input parameter that reflects the air-fuel ratio learning value is changed from the intake air amount, the command fuel injection amount, and the estimated air-fuel ratio information. Thereby, the estimation error of the soot discharge amount can be reduced.

It is a figure for demonstrating the system configuration | structure of the internal combustion engine in Embodiment 1 of this invention. It is a block diagram for demonstrating the outline | summary of a structure of the on-board Soot estimation model with which ECU is provided. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a figure showing the relationship between the index value (= command fuel injection amount / actual fuel injection amount) which shows the deviation | shift amount of fuel injection amount, and command fuel injection amount. It is the figure which divided and expressed A area | region with a large deviation | shift amount of intake air amount, and B area | region where it is small using the driving | operation area | region specified using the EGR rate and the intake air amount (AFM value).

Embodiment 1 FIG.
[Hardware configuration of internal combustion engine]
FIG. 1 is a diagram for explaining a system configuration of an internal combustion engine 10 according to Embodiment 1 of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10. Here, it is assumed that the internal combustion engine 10 is a diesel engine (compression ignition internal combustion engine), which is mounted on a vehicle and used as a power source. Although the internal combustion engine 10 of this embodiment is an in-line four-cylinder type, the number of cylinders and the cylinder arrangement of the internal combustion engine in the present invention are not limited to this.

  An intake passage 12 and an exhaust passage 14 communicate with each cylinder of the internal combustion engine 10. An air flow meter 16 for measuring the amount of intake air is installed in the vicinity of the inlet of the intake passage 12. A compressor 18 a of a turbocharger 18 with a variable nozzle is installed in the intake passage 12 on the downstream side of the air flow meter 16. An intercooler 20 for cooling the air compressed by the compressor 18a is provided in the intake passage 12 downstream of the compressor 18a. A diesel throttle valve 22 is installed in the intake passage 12 downstream of the intercooler 20.

  In order to purify the exhaust gas, an oxidation catalyst 24 and a DPF (Diesel Particulate Filter) 26 are installed in this order from the upstream side in the exhaust passage 14 downstream of the turbine 18b. An air-fuel ratio sensor 28 for detecting the actual air-fuel ratio (actual A / F) of the exhaust gas is attached to the exhaust passage 14 downstream of the DPF 26. Further, the internal combustion engine 10 includes an EGR passage 30 that connects the exhaust passage 14 upstream of the turbine 18 b and the intake passage 12 downstream of the diesel throttle valve 22. An EGR valve 32 for adjusting the flow rate of EGR gas introduced into the intake passage 12 is installed in the middle of the EGR passage 30.

  Further, the system shown in FIG. 1 includes an ECU (Electronic Control Unit) 34. In addition to the air flow meter 16 and the air-fuel ratio sensor 28 described above, various sensors for detecting the operating state of the internal combustion engine 10 such as a crank angle sensor 36 for detecting the engine speed are connected to the input portion of the ECU 34. ing. On the other hand, in addition to the diesel throttle valve 22 and the EGR valve 32 described above, the output of the ECU 34 controls the operation of the internal combustion engine 10 such as a fuel injection valve 38 for injecting fuel into the cylinder of the internal combustion engine 10. Various actuators are connected. The ECU 34 controls the operation of the internal combustion engine 10 by operating various actuators according to the outputs of the various sensors described above and a predetermined program.

[Onboard Soot estimation model]
(Outline of model structure)
FIG. 2 is a block diagram for explaining the outline of the configuration of the onboard Soot estimation model 40 provided in the ECU 34. For the purpose of grasping the amount of soot accumulated on the DPF 26, it is required to estimate the amount of soot discharged from each cylinder during operation. The ECU 34 is virtually constructed with an on-board soot estimation model 40 for estimating the soot discharge amount (discharge amount per unit time) for such a purpose.

More specifically, the onboard soot estimation model (hereinafter simply referred to as “estimation model”) 40 includes a base soot map 42, a base A / F map 44, a current A / F calculation unit 46, a base intake air O _2. A concentration map 48, a current A / F calculation unit 50, an EGR rate calculation unit 52, a current intake O ₂ concentration calculation unit 54, and a transient correction coefficient calculation unit 56 are provided.

  The base soot map 42 is defined by the current operation region (the fuel injection amount and the engine speed) with the engine speed detected using the crank angle sensor 36 and the command fuel injection quantity of the fuel injection valve 38 as input values. Base soot discharge amount which is a basic value (a value in a steady state) of the amount of soot discharged from the cylinder in the operation region).

  The base A / F map 44 uses the engine speed detected using the crank angle sensor 36 and the command fuel injection amount as input values, and is a reference in the current operation region (that is, when calculating the base soot discharge amount). Base A / F is calculated.

  The current A / F calculation unit 46 calculates an estimated A / F, which is an estimated value of the current air-fuel ratio, using the intake air amount measured by the air flow meter 16 and the command fuel injection amount as input values. For example, when the internal combustion engine 10 has deteriorated over time, the estimated A / F deviates from the actual A / F. Therefore, the ECU 34 uses the actual A / F acquired using the air-fuel ratio sensor 28 on the condition that a predetermined learning execution condition is satisfied during the operation of the internal combustion engine 10, and the current A / F calculation unit 46. A / F learning control for learning the difference between the estimated A / F calculated by the above and the actual A / F is executed.

More specifically, according to the A / F learning control, based on the difference between the actual A / F (air-fuel ratio sensor value) and the estimated A / F, the A / F for eliminating the difference. A learning value is calculated. Then, based on the calculated A / F learning value, control for eliminating the above difference (for example, adjustment of the O ₂ concentration in the cylinder by adjusting the opening of the EGR valve 32) is executed. This eliminates the difference between the estimated A / F and the actual A / F.

Next, the base intake O ₂ concentration map 48 uses the engine speed detected by the crank angle sensor 36 and the command fuel injection amount as input values, and calculates the current (that is, the base soot discharge amount). ) Calculate a base O ₂ concentration that is a basic value of the O ₂ concentration in the intake air in the operation region. The configuration of the current A / F calculation unit 50 is the same as the configuration of the current A / F calculation unit 46.

The EGR rate is a value defined as the ratio of the EGR gas amount to the in-cylinder gas amount (sum of the fresh air amount and the EGR gas amount) filled in the cylinder. The EGR rate calculation unit 52 calculates the EGR rate using the intake air amount measured by the air flow meter 16 and the in-cylinder gas amount acquired by any known method as input values. Further, the current intake O ₂ concentration calculating section 54, as an input value and an estimated air-fuel ratio and the EGR rate, and calculates the current intake O ₂ concentration.

Further, in the estimation model 40, the A / F ratio and the intake O ₂ concentration ratio used as inputs of the transient correction coefficient calculation unit 56 are calculated. The A / F ratio is calculated as a ratio between the base A / F calculated by the base A / F map 44 and the estimated A / F calculated by the current A / F calculation unit 46. Intake O ₂ concentration ratio is calculated as the ratio of the base O ₂ concentration calculated by the base intake O ₂ concentration map 48, and the current current intake O ₂ concentration was calculated by the intake O ₂ concentration calculation unit 54.

The transient correction coefficient calculation unit 56 uses the A / F ratio and the intake air O ₂ concentration ratio as input values as described above, and performs a soot at the time of transition with respect to a value when the internal combustion engine 10 is in a steady state (base soot emission amount). A transient correction coefficient for correcting an increase / decrease in the emission amount is calculated. In the estimation model 40, the final soot discharge estimated value is calculated by correcting the base soot discharge using such a transient correction coefficient. More specifically, while using a base correction amount based on the A / F ratio and the intake air O ₂ concentration ratio based on the base A / F and the base intake air O ₂ concentration, respectively, the base soot emission amount is used as a basis. It is possible to calculate the final soot discharge amount in consideration of the transient air-fuel ratio and the effect of changes in the intake O ₂ concentration.

(Characteristic reflection method of A / F learning value)
The conventional on-board soot estimation model can exhibit high accuracy for the internal combustion engine used at the time of model adaptation, but the estimation accuracy decreases when it is affected by aging deterioration of the internal combustion engine and machine difference variation. In the estimation model 40 of the present embodiment, the A / F learning value (learning value regarding the deviation amount of the air-fuel ratio) obtained by using the actual A / F detected by the air-fuel ratio sensor 28 is used as each input value of the model. Processing to reflect is performed.

  In addition, in the estimation model 40, the following method is used when the A / F learning value is reflected in the input value of the model. That is, in the estimation model 40, the factor (main cause) that causes the deviation of the air-fuel ratio is the deviation of the intake air amount, the deviation of the fuel injection amount, or the deviation of both the intake air amount and the fuel injection amount. Is determined. Then, the reflection destination of the A / F learning value is changed according to the determination result. Specifically, (1) when the difference in intake air amount is the main cause, the A / F learning value is reflected on the intake air amount as each input of the estimation model 40 as shown in FIG. The (2) When the deviation of the fuel injection amount is the main cause, the A / F learning value is reflected on the command fuel injection amount as each input of the estimation model 40. Also, (3) when the difference between both the intake air amount and the fuel injection amount is the main cause, the A / F learning value is reflected on the air-fuel ratio (estimated A / F) as each input of the estimation model 40. Is done.

  FIG. 3 is a flowchart showing a routine executed by the ECU 34 in order to realize the process of reflecting the A / F learning value to each model input described above. Note that this routine is repeatedly executed at predetermined control cycles in a situation where there is a deviation between the estimated A / F and the actual A / F due to the execution of the A / F learning control described above. Shall be.

  In the routine shown in FIG. 3, the ECU 34 first acquires the current command fuel injection amount, intake air amount, and EGR rate in step 100. More specifically, the ECU 34 stores a map (not shown) that defines the command fuel injection amount in relation to the operation region of the internal combustion engine 10 (specified by the intake air amount and the engine speed). The command fuel injection amount is acquired with reference to such a map. The intake air amount acquired here is a measured value (AFM value) of the air flow meter 16. The EGR rate is calculated using the EGR rate calculation unit 52.

  Next, the ECU 34 proceeds to step 102 and determines whether or not the current command fuel injection amount is less than a predetermined threshold value. FIG. 4 is a diagram showing the relationship between the index value (= command fuel injection amount / actual fuel injection amount) indicating the deviation amount of the fuel injection amount and the command fuel injection amount. As the index value increases with respect to 1 and decreases with respect to 1, the deviation of the command fuel injection amount from the actual fuel injection amount increases. Therefore, it can be seen from FIG. 4 that the deviation amount of the fuel injection amount tends to increase as the command fuel injection amount decreases. In consideration of the tendency shown in FIG. 4, the ECU 34 stores a threshold value of a command fuel injection amount (a value adapted in advance by an experiment) for determining the magnitude of the deviation amount of the fuel injection amount.

  If it is determined in step 102 that the command fuel injection amount is smaller than the threshold value, the ECU 34 proceeds to step 104, where the deviation amount between the measured value (AFM value) of the intake air amount and the actual value is large. Or if it is in a small situation. FIG. 5 is a diagram in which an A region where the amount of deviation of the intake air amount is large and a B region where the intake air amount is small are partitioned using the operation region specified using the EGR rate and the intake air amount (AFM value). It is. More specifically, the A region where the amount of deviation of the intake air amount is large tends to increase as the EGR rate increases under the condition where the AFM value is small. In consideration of such a tendency, the ECU 34 sets a threshold value that is a boundary of the operation region for determining the magnitude of the deviation amount of the intake air amount (a value that is previously adapted in an experiment and is set as shown in FIG. 5). Stored) is stored. In step 104, the ECU 34 determines that the amount of deviation of the intake air amount is large when the coordinates of the current values of the AFM value and the EGR rate acquired in step 100 are located in the A region. Is located in the region B, it is determined that the amount of deviation of the intake air amount is small.

  The ECU 34 proceeds to step 106 when the determination at step 104 is established. In this case, since the difference between the fuel injection amount and the intake air amount is both large, it is impossible to determine exactly which of the fuel injection amount and the intake air amount is the main cause of the air-fuel ratio difference. For this reason, in step 106, the ECU 34 determines that the main cause of the deviation of the air-fuel ratio is the deviation of both the intake air amount and the fuel injection amount, and then, the air-fuel ratio (estimated A / A process of reflecting the A / F learning value is performed on F). Specifically, as shown in FIG. 2, a process of reflecting the A / F learning value on the estimated A / F calculated by the current A / F calculation units 46 and 50 is performed. As a result, an estimated A / F that takes into account the influence of the deviation of the air-fuel ratio can be obtained.

On the other hand, if the determination in step 104 is not established, that is, if it can be determined that the amount of deviation of the intake air amount is small, the ECU 34 proceeds to step 108. In this case, only the deviation amount of the fuel injection amount is large. For this reason, in step 108, the ECU 34 determines that the main cause of the deviation of the air-fuel ratio is the deviation of the fuel injection amount, and then the A / F learning value for the command fuel injection amount as each input of the estimation model 40. Process to reflect. Specifically, as shown in FIG. 2, the command fuel injection amount input to the base soot map 42, the base A / F map 44, the current A / F calculation units 46 and 50, and the base intake O ₂ concentration map 48. Is processed to reflect the A / F learning value. In this case, the A / F learning value is reflected by, for example, a method of calculating the correction value of the fuel injection amount deviation by calculating backward from the A / F learning value and reflecting the correction value on the command fuel injection amount. Can do. As a result, the command fuel injection amount as the model input is corrected so that the influence of the air-fuel ratio shift is taken into consideration.

  If the determination in step 102 is not established, the ECU 34 proceeds to step 110 and determines the amount of deviation of the intake air amount by the same process as step 104. As a result, the ECU 34 proceeds to step 112 when the determination at step 110 is established. In this case, only the deviation of the intake air amount is large. For this reason, in step 112, the ECU 34 determines that the main cause of the air-fuel ratio deviation is the intake air amount deviation, and then sets the A / F learning value for the intake air amount as each input of the estimation model 40. Process to reflect. Specifically, as shown in FIG. 2, a process of reflecting the A / F learning value on the intake air amount currently input to the A / F calculation units 46 and 50 is performed. In this case, the A / F learning value is reflected by, for example, a method of calculating the correction value of the intake air amount deviation by calculating backward from the A / F learning value and reflecting the correction value on the intake air amount. it can. As a result, the intake air amount as the model input is corrected so as to have a value that takes into account the influence of the deviation of the air-fuel ratio.

  If the determination in step 110 is not established, the ECU 34 proceeds to step 114. In this case, since the difference between the fuel injection amount and the intake air amount is both small, it cannot be determined exactly which of the fuel injection amount and the intake air amount is the main cause of the air-fuel ratio difference. For this reason, in step 114, the ECU 34 determines that the main cause of the deviation of the air-fuel ratio is the deviation of both the intake air amount and the fuel injection amount, and then, as in step 108, as the respective inputs of the estimation model 40 Processing for reflecting the A / F learning value on the air-fuel ratio (estimated A / F) is performed.

Unlike the processing of the routine shown in FIG. 3 described above, the A / F learning value is uniformly reflected only on the estimated A / F without considering the cause of the deviation of the air-fuel ratio. The following problems occur. In other words, as an example, the case where the difference in fuel injection amount is the main cause of the difference in air-fuel ratio will be described as an example. In this case, the base soot map 42, the base A / F map 44, the current A / F calculation units 46 and 50, and the base intake air O ₂ , even though the fuel injection amount shift is the main cause of the air-fuel ratio shift. The A / F learning value is not reflected on the command fuel injection amount input to the concentration map 48. Among the components of the estimation model 40, regarding the current A / F calculation units 46 and 50, since the A / F learning value is reflected on the estimation A / F, the deviation of the air-fuel ratio with respect to the output value is determined. Is considered. However, in the other base soot map 42, base A / F map 44, and base intake O ₂ concentration map 48, the command fuel injection amount as an input remains shifted, so the base soot discharge amount, base A / F and the base intake O ₂ concentration, and the calculated value of the transient correction coefficient calculated on the basis thereof will cause an error. This becomes an estimation error factor of the soot discharge amount calculated by the estimation model 40.

  On the other hand, according to the routine shown in FIG. 3 described above, there are three causes of the deviation of the air-fuel ratio: the deviation of the intake air amount, the deviation of the fuel injection amount, and the deviation of both the intake air amount and the fuel injection amount. being classified. Then, the reflection destination of the A / F learning value is changed according to which of the three causes of the deviation of the air-fuel ratio. More specifically, the input parameter that reflects the air-fuel ratio learning value is changed from among the intake air amount, the command fuel injection amount, and the estimated A / F. Thereby, the estimation error of the soot discharge amount calculated by the estimation model 40 can be reduced.

  In the first embodiment described above, the “air amount acquisition means” in the first aspect of the present invention is realized by the ECU 34 executing the processing of step 100, and the ECU 34 uses the air-fuel ratio sensor 28. By acquiring the actual A / F, the “actual air / fuel ratio acquiring means” in the first aspect of the present invention is realized, and the ECU 34 calculates the estimated A / F using the current A / F calculation unit 46 or 50. Thus, the “estimated air-fuel ratio calculating means” in the first invention is realized, and the “air-fuel ratio learning control means” in the first invention is realized by the ECU 34 executing the A / F learning control described above. The ECU 34 uses the on-board soot estimation model 40 while using the method for reflecting the A / F learning value by the series of processes in steps 102 to 114 described above. "Soot calculation means" is realized in the invention by calculating the door emissions.

  By the way, in Embodiment 1 mentioned above, about the example which uses an air fuel ratio (A / F) as air fuel ratio information (actual air fuel ratio information and estimated air fuel ratio information) used for calculation of the soot discharge amount by the estimation model 40. Although described, the air-fuel ratio information used in the present invention is not limited to the air-fuel ratio itself, and may be an excess air ratio or an equivalence ratio.

Reference Signs List 10 internal combustion engine 12 intake passage 14 exhaust passage 16 air flow meter 18 turbocharger 20 intercooler 22 diesel throttle valve 24 oxidation catalyst 26 DPF
28 Air-fuel ratio sensor 30 EGR passage 32 EGR valve 34 ECU (Electronic Control Unit)
36 Crank angle sensor 38 Fuel injection valve 40 On-board soot estimation model 42 Base soot map 44 Base A / F map 46, 50 Current A / F calculation unit 48 Base intake O ₂ concentration map 52 EGR rate calculation unit 54 Current intake O ₂ Concentration calculator 56 Transient correction coefficient calculator

Claims (1)

A fuel injection valve for supplying fuel to the internal combustion engine;
An air amount acquisition means for acquiring an intake air amount using an air flow meter disposed in the intake passage;
Real air-fuel ratio acquisition means for acquiring real air-fuel ratio information using an air-fuel ratio sensor disposed in the exhaust passage;
Estimated air-fuel ratio calculating means for calculating estimated air-fuel ratio information based on an intake air amount and a command fuel injection amount of the fuel injection valve;
Learning the difference between the actual air-fuel ratio information and the estimated air-fuel ratio information, and air-fuel ratio learning control means for controlling the internal combustion engine so that the difference becomes smaller;
Soot calculation means for calculating a soot discharge amount that is a discharge amount of soot discharged from the cylinder, using parameters including the intake air amount, command fuel injection amount, and estimated air-fuel ratio information as input values;
With
The soot calculating means includes
The command fuel injection amount is equal to or greater than a predetermined value, and the current operation region is an operation region specified using the EGR rate and the intake air amount, and the difference between the measured value of the intake air amount and the actual value is relative The intake air amount corrected using the air-fuel ratio learning value based on the learning of the difference by the air-fuel ratio learning control means is used as an input value for calculating the soot discharge amount. ,
The command fuel injection amount is less than the predetermined value, and the current operation region is an operation region specified using the EGR rate and the intake air amount, and the difference between the measured value of the intake air amount and the actual value is relative If the command fuel injection amount corrected using the air-fuel ratio learning value is used as an input value for calculating the soot discharge amount,
When the command fuel injection amount is less than the predetermined value and the current operation region is in the first operation region, or the command fuel injection amount is greater than or equal to the predetermined value and the current operation region is the second operation region. A soot emission estimation device for an internal combustion engine, wherein the estimated air-fuel ratio information corrected using the air-fuel ratio learning value is used as an input value for calculating a soot emission amount when in the operating region.

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