JP2014206103A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that can improve accuracy in estimating a NOx amount.SOLUTION: In a control device for an internal combustion engine that includes a cylinder internal pressure sensor and a fuel injection valve, a NOx amount generated by combustion is estimated based on an operational state of an internal combustion engine. After that, a cylinder internal temperature is calculated based on an internal pressure, a difference between a reference cylinder internal temperature that is set based on an operational state of the internal combustion engine and an actual cylinder internal temperature is calculated for each operation region of the internal combustion engine, and based on the difference, a NOx correction amount is calculated. Based on the NOx correction amount, an estimated NOx amount is corrected.

Description

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

  Conventionally, for the purpose of reducing the number of sensors in an internal combustion engine, a method for estimating the amount of NOx contained in exhaust gas (hereinafter simply referred to as NOx amount) based on the operating state is known. For example, Patent Document 1 discloses a method of calculating the in-cylinder temperature during combustion based on the engine speed and the fuel injection amount, and estimating the NOx amount using this in-cylinder temperature. The reason for using the in-cylinder temperature during combustion in this method is that the NOx amount increases as the in-cylinder temperature during combustion increases, and the NOx amount decreases as the in-cylinder temperature during combustion decreases (enlarged Zeldovic mechanism). Because there is. By utilizing this characteristic, an estimated value of the NOx amount can be calculated.

  Patent Document 1 discloses control for correcting the fuel injection timing so that the estimated value becomes a predetermined target value. Specifically, when the estimated value is higher than the target value, the fuel injection timing is retarded. As a result, the in-cylinder temperature decreases and the amount of NOx decreases. On the other hand, when the estimated value is lower than the target value, the fuel injection timing is advanced. As a result, the in-cylinder temperature rises and the amount of NOx increases. By correcting the fuel injection timing in this way, the in-cylinder temperature is changed, and the NOx amount is brought close to the target value. As a result, it is possible to suppress deterioration in fuel consumption and increase in the amount of particulate matter generated in the diesel engine caused by the NOx amount being away from the target value.

JP 2005-139984 A JP 2008-309006 A JP 2008-286019 A JP 2007-127004 A

  By the way, factors that affect the amount of NOx include the amount of moisture contained in fresh air (hereinafter referred to as humidity), differences in fuel properties, and variations in the injection characteristics of the fuel injection valve. However, these factors are not reflected in the above method for estimating the amount of NOx. For this reason, there is a possibility that a deviation will occur between the actual NOx amount and the estimated value.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can improve the estimation accuracy of the NOx amount.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
An in-cylinder pressure sensor for detecting an in-cylinder pressure of the internal combustion engine;
A control device for an internal combustion engine comprising: a fuel injection valve that injects fuel into the internal combustion engine;
NOx amount estimating means for estimating the amount of NOx generated by combustion based on the operating state of the internal combustion engine;
In-cylinder temperature calculating means for calculating an in-cylinder temperature based on the in-cylinder pressure;
In-cylinder temperature difference amount calculating means for calculating a difference between a reference in-cylinder temperature set based on an operating state of the internal combustion engine and an actual in-cylinder temperature for each operation region of the internal combustion engine;
NOx correction amount calculating means for calculating a NOx correction amount based on the difference;
Estimated NOx amount correcting means for correcting the NOx amount estimated by the NOx amount estimating means by the NOx correction amount;
It is characterized by providing.

The second invention is the first invention, wherein
The in-cylinder temperature difference amount calculating means calculates the difference in the operation region at the time of the deceleration fuel cut and the difference in the light load operation region,
The NOx correction amount calculating means calculates a first NOx correction amount from a difference in the operation region at the time of the deceleration fuel cut, and a second NOx correction amount is calculated based on the first NOx correction amount and the difference in the light load operation region. NOx correction amount of
The estimated NOx amount correcting means corrects the NOx amount estimated by the NOx amount estimating means by at least one of the first NOx correction amount and the second NOx correction amount.

The third invention is the second invention, wherein
The in-cylinder temperature difference amount calculating means includes means for calculating a difference in the middle and high load operation region,
The estimated NOx amount correction means includes means for calculating the second NOx correction amount from the difference in the medium-high load operation region instead of the first NOx correction amount and the difference in the light load operation region. It is characterized by.

Moreover, 4th invention is 2nd or 3rd invention,
Injection timing determining means for determining the fuel injection timing based on the operating state of the internal combustion engine;
Injection timing advance means for advancing the fuel injection timing determined by the injection timing determination means based on the second NOx correction amount;
The estimated NOx amount correcting means corrects the NOx amount estimated by the NOx amount estimating means with the first NOx correction amount.

  According to the first to third inventions, the estimated NOx amount can be directly corrected. As a result, the estimated NOx amount and the actual NOx amount can be brought close to each other.

  According to the fourth invention, the in-cylinder temperature can be raised by advancing the fuel injection timing. If the in-cylinder temperature is raised, the amount of NOx contained in the exhaust gas can be increased, and the amount of NOx contained in the exhaust gas can be set to an appropriate ratio.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram for demonstrating the structure of the system of Embodiment 1 of this invention. It is a figure shown about the driving | operation area | region of the engine in this embodiment. It is a figure which shows having separated the factor which affects the amount of NOx for every driving | running area. It is the figure which compared the in-cylinder temperature in 1 combustion cycle, and the estimation base in the driving | operation area | region at the time of a deceleration fuel cut. It is the figure which compared the in-cylinder temperature in 1 combustion cycle, and the estimation base in a light load operation area | region. It is the figure which compared the in-cylinder temperature in 1 combustion cycle, and the estimation base in a medium and high load operation area | region. It is an image figure showing the relationship between the in-cylinder temperature change amount X and the first advance angle correction amount. It is an image figure showing the relationship between the 1st NOx correction amount and the 1st advance angle correction amount. It is an image figure showing the relationship between the in-cylinder temperature change amount Y and the 2nd advance angle correction amount. It is an image figure showing the relationship between the 2nd NOx correction amount and the 2nd advance angle correction amount. 4 is a flowchart of first and second advance angle correction amount calculation routines executed by the ECU in the first embodiment.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram for explaining the configuration of the system according to the first embodiment of the present invention. The system shown in FIG. 1 includes an engine 10. The engine 10 is a diesel engine having four cylinders 27. The number of cylinders and the cylinder arrangement of the engine 10 are not particularly limited.

  An intake manifold 20 is connected to the intake port of each cylinder 27 of the engine 10. The intake manifold 20 is provided with an intercooler 18, a compressor 16, and an air flow sensor 14 sequentially from the cylinder 27 toward the upstream. Fresh air is taken in from the air flow sensor 14 side, and fresh air is supplied to each cylinder 27 via the intake manifold 20.

  The engine 10 includes a fuel tank 22 and a common rail system 24. One fuel injection valve 26 of the common rail system 24 is disposed in each cylinder 27 of the engine 10. The fuel obtained from the fuel tank 22 is injected into each cylinder by the common rail system 24. The common rail system 24 is a system that can perform fuel injection at a plurality of timings during one combustion cycle (so-called multi-injection in which each timing is referred to as pilot, main, etc.). The common rail system 24 is configured to be able to change the injection amount, advance / retard the injection timing, and change the number of injections.

  Each cylinder 27 of the engine 10 is provided with one in-cylinder pressure sensor 28 for measuring the pressure in the cylinder 27 during combustion.

  An exhaust manifold 30 is connected to the exhaust port of each cylinder 27 of the engine 10. The exhaust manifold 30 is connected to the exhaust passage 33 via the turbine 32. In the exhaust passage 33, from the turbine 32, the DOC (Diesel Oxidation Catalyst) 34, the DPR (Diesel Particulate active-Reduction) 36, the first SCR (Selective Catalytic Reduction) 38, the second SCR 48, and ammonia An oxidation catalyst (ASC) 50 is provided. The DOC 34 is provided to oxidize HC, CO, and NO in the exhaust gas. The DPR 36 is provided for collecting and removing particulate matter (hereinafter referred to as PM) in the exhaust gas. The first SCR 38 and the second SCR 48 are provided to remove NOx contained in the exhaust gas. The ASC 50 is provided to prevent ammonia from being discharged to the outside.

  A urea water injection valve 42 is provided between the DPR 36 and the first SCR 38. The urea water injection valve 42 is connected to a urea water tank 44 that stores urea water therein via a supply pump (not shown). The urea water in the urea water tank 44 is injected from the urea water injection valve 42 toward the first SCR 38 by driving the supply pump. Urea contained in the injected urea water is hydrolyzed into ammonia in the first SCR 38. This ammonia reacts with NOx in the exhaust gas to generate water and nitrogen. In this way, NOx can be purified in the first SCR 38. A NOx sensor 40 is provided in the exhaust passage 33 downstream of the ASC 50. The NOx sensor 40 is provided to perform feedback control of the urea water injection amount. Further, exhaust temperature sensors 46 are attached to the exhaust passage 33 at various places.

  The system configuration of this embodiment includes an ECU (Engine Control Unit) 100. An airflow sensor 14, an in-cylinder pressure sensor 28, a NOx sensor 40, and an exhaust temperature sensor 46 are connected to the input side of the ECU 100. The air flow sensor 14 outputs a signal corresponding to the intake air amount. The in-cylinder pressure sensor 28 outputs a signal corresponding to the pressure in the cylinder 27 (in-cylinder pressure). The NOx sensor 40 outputs a signal corresponding to the NOx concentration in the exhaust gas after passing through the first ASC 50. In addition, a crank angle sensor (not shown) that is a sensor provided in the engine 10 is connected to the input side of the ECU 100. The crank angle sensor outputs a signal corresponding to the engine speed.

  A fuel injection valve 26 and a urea water injection valve 42 are connected to the output side of the ECU 100. The ECU 100 can control the fuel injection amount and the fuel injection timing by adjusting the opening timing of the fuel injection valve 26. The ECU 100 can control the urea water injection amount by adjusting the opening timing of the urea water injection valve 42.

  In the engine 10 of the present embodiment, the fuel injection timing is controlled in order to adjust the ratio of NOx and PM contained in the exhaust gas. Hereinafter, it will be described in detail how NOx and PM contained in the exhaust gas change by controlling the fuel injection timing.

  As ECU 100 advances the fuel injection timing, the in-cylinder temperature during combustion rises. As a result, the amount of NOx (NOx amount) contained in the exhaust gas increases, and the amount of PM (PM amount) contained in the gas decreases. On the other hand, the ECU 100 retards the fuel injection timing, so that the in-cylinder temperature during combustion decreases. As a result, the NOx amount decreases and the PM amount increases. As described above, the ECU 100 controls the fuel injection timing to change the in-cylinder temperature, thereby adjusting NOx and PM contained in the exhaust gas.

  Therefore, a target value for the NOx amount is set in the ECU 100 as an index for controlling the fuel injection timing. By bringing the actual NOx amount close to this target value, it is possible to prevent either the NOx amount or the PM amount contained in the exhaust gas from becoming excessive. However, the sensor that can detect the actual amount of NOx is not attached to the engine 10. The NOx sensor 40 is provided downstream of the first SCR 38 and the second SCR 48. For this reason, the NOx amount in the exhaust gas detected by the NOx sensor 40 is detected after the NOx is removed. Therefore, the NOx sensor 40 cannot detect the amount of NOx contained in the gas generated by combustion.

  Therefore, the engine 10 in the present embodiment employs a method of estimating the amount of NOx contained in the gas generated by combustion based on the operating state. According to this method, the NOx amount can be estimated based on, for example, the engine speed, the fuel injection amount, the intake air amount, and the like.

  However, in the above method, the amount of moisture (humidity) contained in the fresh air sucked into the cylinder 27, which is a factor affecting the amount of NOx, the property of the fuel supplied to the fuel tank 22, for example, cetane of light oil The difference in price and the injection system variation in the fuel injection valve 26 cannot be reflected. For this reason, when these factors affect the NOx amount, there is a possibility that a deviation occurs between the actual NOx amount and the estimated NOx amount. Here, the injection system variation is variation due to the injection characteristic of the fuel injection valve 26. Specifically, there are variations in the injection amount, variations in the injection timing, and the like.

  As a result of considering the factors causing the above-described deviation, it has been found that the degree of influence of each factor differs depending on the operating region of the engine 10. This consideration will be described in detail below with reference to FIGS.

  FIG. 2 is a diagram illustrating an operation region of the engine 10 in the present embodiment. In FIG. 2, the vertical axis indicates the shaft torque Te, and the horizontal axis indicates the engine speed Ne.

  A region indicated by A in FIG. 2 is an operation region during deceleration fuel cut. The operation region at the time of deceleration fuel cut is a region when the vehicle is decelerating, and fuel injection from the fuel injection valve 26 is not performed.

  A region indicated by B in FIG. 2 is a light load operation region. In the light load operation region, premixed combustion is performed according to the advance angle of the fuel injection timing. The light load operation region includes an operation region during idling.

  A region indicated by C in FIG. 2 is a medium to high load operation region. In the middle and high load operation region, diffusion combustion is performed by the advance angle of the fuel injection timing. During diffusion combustion, pilot injection is performed as necessary separately from the main injection.

  Next, with reference to FIG. 3, it will be described in which operating region the humidity, fuel properties, and injection system variation affect the NOx amount. FIG. 3 is a diagram showing that factors that affect the NOx amount are separated for each operation region.

  As shown in FIG. 3, it was found that the influence of humidity becomes significant in the operation region (region A in FIG. 2) at the time of deceleration fuel cut. This is because fuel injection is not performed at the time of the deceleration fuel cut, so that the influence of moisture contained in fresh air becomes high.

  As shown in FIG. 3, it was found that in the light load operation region (region B in FIG. 2), the influence of humidity and the influence of cetane number and injection system variation become significant.

  As shown in FIG. 3, it was found that the influence of the cetane number and the variation in the injection system becomes significant in the medium and high load operation region (region C in FIG. 2).

  Thus, it has been found that the influence of humidity, which is an influence on the amount of NOx, and the influence of cetane number and injection system variation can be separated for each operation region. Therefore, in the present embodiment, in-cylinder temperature is calculated from the in-cylinder pressure detected by the in-cylinder pressure sensor 28 for each of the three operating regions in order to grasp the influence of humidity and the influence of cetane number and hardware variation. . Then, using this in-cylinder temperature, finally, a process for bringing the actual NOx amount close to the estimated NOx amount is performed. The specific contents of this process will be described below with reference to FIGS.

  FIG. 4 is a diagram comparing the in-cylinder temperature during one combustion cycle and the estimated base in the operation region at the time of deceleration fuel cut. In FIG. 4, the vertical axis represents the in-cylinder temperature, and the horizontal axis represents the crank angle. A solid line in FIG. 4 shows an estimation base. The estimated base is a reference in-cylinder temperature in the operation region set in advance in the ECU 100. What is indicated by a broken line in FIG. 4 is the actual in-cylinder temperature calculated from the in-cylinder pressure detected at the time of deceleration fuel cut.

  In FIG. 4, X represents the difference in each peak between the reference in-cylinder temperature and the actual in-cylinder temperature. This difference indicated by X is an in-cylinder temperature change amount X that is a difference between the reference in-cylinder temperature and the actual in-cylinder temperature. The in-cylinder temperature change amount X calculated in the operation region at the time of deceleration fuel cut corresponds to a value obtained by quantifying the influence of humidity. This is because, as described with reference to FIG. 3, the influence of humidity becomes significant as a cause of the deviation of the NOx amount at the time of deceleration fuel cut. By calculating the in-cylinder temperature change amount X, it is possible to grasp the influence of humidity among the deviations in the NOx amount.

  FIG. 5 is a diagram comparing the in-cylinder temperature during one combustion cycle and the estimated base in the light load operation region. In FIG. 5, the difference in peak between the reference in-cylinder temperature and the actual in-cylinder temperature is indicated by X and Y. This difference indicated by X and Y is the in-cylinder temperature change amount X and the in-cylinder temperature change amount Y. The in-cylinder temperature change amount X corresponds to the influence of humidity, and the in-cylinder temperature change amount Y corresponds to the numerical value of the influence of cetane number and injection system variation. This is because, as described with reference to FIG. 3, in the light load operation region, the influence of humidity and the influence of cetane number and injection system variation become significant. In addition, as shown in FIG. 5, the in-cylinder temperature change amount X corresponding to the influence of humidity and the in-cylinder temperature change amount Y corresponding to the cetane number and the injection system variation each independently influence the in-cylinder temperature. Is given. For this reason, the numerical value of the entire in-cylinder temperature change amount calculated in the light load operation region can be calculated as the sum of the in-cylinder temperature change amount X and the in-cylinder temperature change amount Y.

  FIG. 6 is a diagram comparing the in-cylinder temperature during one combustion cycle with the estimated base in the medium and high load operation region. In the middle and high load operation region, as described with reference to FIG. 3, the influence of the cetane number and the variation in the injection system becomes significant as a cause of the deviation of the NOx amount. Therefore, by calculating the difference Y (in-cylinder temperature change amount Y) in the same manner as in FIG. 4, it is possible to grasp the influence of the cetane number and the injection system variation among the NOx amount deviations.

  The difference between the in-cylinder temperature change amount X and the in-cylinder temperature change amount Y calculated in the light load operation region and the in-cylinder temperature change amount X calculated in the operation region at the time of deceleration fuel cut is the in-cylinder temperature change amount. Y. Therefore, the in-cylinder temperature change amount Y is calculated by subtracting the in-cylinder temperature change amount X calculated in the operation region at the time of deceleration fuel cut from the entire in-cylinder temperature change amount calculated in the light load operation region. be able to. Thereby, it is possible to grasp the influence of the cetane number and the variation in the injection system among the deviation of the NOx amount.

  As described above, by obtaining the in-cylinder temperature change amount in any two of the above three operation regions, the amount of NOx displacement due to the influence of humidity, the cetane number, and the influence of the injection system variation Thus, it is possible to grasp both of the amount of deviation of the NOx amount.

  Next, a method for calculating a correction amount for bringing the estimated NOx amount close to the actual NOx amount using the calculated in-cylinder temperature change amount will be described. In the present embodiment, the ECU 100 calculates two types of correction amounts. The first is an advance correction amount for advancing the timing of main injection in the medium and high load operation region. The second is a NOx correction amount for correcting the estimated value of the NOx amount. The calculation of the two types of correction amounts will be described below with reference to FIGS.

  FIG. 7 is an image diagram showing the relationship between the in-cylinder temperature change amount X and the first advance angle correction amount. If the relationship shown in FIG. 7 is used, the first advance angle correction amount can be calculated from the in-cylinder temperature change amount X. The first advance angle correction amount is a value calculated for advancing the fuel injection timing by the influence of humidity.

  FIG. 8 is an image diagram showing the relationship between the first NOx correction amount and the first advance angle correction amount. If the relationship shown in FIG. 8 is used, the first NOx correction amount can be calculated from the first advance angle correction amount. The first NOx correction amount is a value calculated for correcting the estimated value of the NOx amount due to the influence of humidity.

  FIG. 9 is an image diagram showing the relationship between the in-cylinder temperature change amount Y and the second advance angle correction amount. If the relationship shown in FIG. 9 is used, the second advance angle correction amount can be calculated from the in-cylinder temperature change amount Y. The second advance angle correction amount is a value calculated to advance the fuel injection timing by the influence of the cetane number and the injection system variation.

  FIG. 10 is an image diagram showing the relationship between the second NOx correction amount and the second advance angle correction amount. If the relationship shown in FIG. 10 is used, the second NOx correction amount can be calculated from the second advance correction amount. The second NOx correction amount is a value calculated in order to correct the estimated value of the NOx amount and the influence of cetane number and injection system variation.

[First and second advance angle correction amount calculation routines]
FIG. 11 is a flowchart of first and second advance angle correction amount calculation routines executed by ECU 100 in the first embodiment. The ECU 100 has a memory for storing this routine. The ECU 100 has a processor for executing the stored routine.

  In this routine, first, an initial value is read (S100). The initial value is the first advance angle correction amount and the second advance angle correction amount stored last time.

  Next, it is determined whether or not a deceleration fuel cut is in progress (S102). The ECU 100 determines whether or not the current operation region is the region A shown in FIG. If it is determined in S102 that the vehicle is not decelerating, then the process of S106 is executed.

  On the other hand, if it is determined in S102 that the vehicle is decelerating, a first advance angle correction amount is calculated (S104). First, as shown in FIG. 4, the ECU 100 calculates the in-cylinder temperature change amount X from the difference between the reference in-cylinder temperature and the actual in-cylinder temperature. Next, the ECU 100 calculates a first advance correction amount based on the in-cylinder temperature change amount X. ECU 100 stores the calculated first advance correction amount as an initial value.

  Next, it is determined whether or not a light load operation is being performed (S106). The ECU 100 determines whether or not the current operation area is the area B shown in FIG. In S106, when it is determined that the light load operation is not being performed, the process of S110 is executed next.

  On the other hand, when it is determined in S106 that the vehicle is operating at a light load, a first advance angle correction amount and a second advance angle correction amount are calculated (S108). First, as shown in FIG. 5, the ECU 100 calculates the in-cylinder temperature change amount from the difference between the reference in-cylinder temperature and the actual in-cylinder temperature. The in-cylinder temperature change amount calculated here includes both the in-cylinder temperature change amount X and the in-cylinder temperature change amount Y. Therefore, the ECU 100 calculates either the in-cylinder temperature change amount X or the in-cylinder temperature change amount Y based on the initial value read in S100. Then, either the in-cylinder temperature change amount X or the in-cylinder temperature change amount Y calculated based on the initial value from the in-cylinder temperature change amount calculated from the difference between the reference in-cylinder temperature and the actual in-cylinder temperature. pull. Thereby, both numerical values of the in-cylinder temperature change amount X and the in-cylinder temperature change amount Y can be obtained. Then, the first advance angle correction amount and the second advance angle correction amount are calculated from these numerical values. In S108, either the in-cylinder temperature change amount X or the in-cylinder temperature change amount Y is calculated based on the initial value read in S100. This is because the time stored as the initial value is new. Priority is given to the calculation.

  Next, it is determined whether or not the middle / high load operation is being performed (S110). The ECU 100 determines whether or not the current operation area is the area C shown in FIG. In S110, when it is determined that the middle / high load operation is not being performed, this routine ends.

  On the other hand, if it is determined in S110 that the vehicle is operating at a medium to high load, a second advance angle correction amount is calculated (S112). First, as shown in FIG. 6, the ECU 100 calculates the in-cylinder temperature change amount Y from the difference between the reference in-cylinder temperature and the actual in-cylinder temperature. Next, the ECU 100 calculates a second advance angle correction amount based on the in-cylinder temperature change amount Y. Then, ECU 100 stores the calculated second advance angle correction amount as an initial value. Thereafter, this routine ends.

[How to use the correction amount]
There are the following three methods of using the first and second advance angle correction amounts and the first and second NOx correction amounts described above.

  As a first method, there is a method in which the timing of the main injection of fuel is advanced by an amount corresponding to the first and second advance angle correction amounts. Thereby, the in-cylinder temperature can be raised. For this reason, the actual in-cylinder temperature can be brought close to the reference in-cylinder temperature. As a result, it is possible to suppress deterioration in fuel consumption and increase in the amount of particulate matter (PM) generated in the diesel engine.

  As a second method, there is a method of correcting the estimated value of the NOx amount by the amount of the first and second NOx correction amounts. As a result, the influence of humidity, the influence of cetane number and injection system variation, and the estimated value of the NOx amount can be directly corrected.

  As a third method, there is a method of correcting the estimated value of NOx by the first NOx correction amount and advancing the fuel injection timing by the second advance correction amount.

  The in-cylinder temperature change amount Y calculated in the middle and high load operation region indicates the cetane number and the injection system variation before the advance angle correction, and indicates the remainder that cannot be corrected after the advance angle correction. ing. Therefore, if the in-cylinder temperature change amount Y is used before the advance angle correction, the influence of the cetane number and the injection system variation can be corrected, and if the in-cylinder temperature change amount Y is used after the advance angle correction, it cannot be corrected. The affected part can be corrected.

  8 and 10, the first and second NOx correction amounts are calculated based on the first and second advance angle correction amounts, but are not limited thereto. The first and second NOx correction amounts can also be calculated based on the in-cylinder temperature change amount X and the in-cylinder temperature change amount Y.

10 Engine 22 Fuel tank 24 Common rail system 26 Fuel injection valve 27 Cylinder 28 In-cylinder pressure sensor 100 ECU

Claims (4)

An in-cylinder pressure sensor for detecting an in-cylinder pressure of the internal combustion engine;
A control device for an internal combustion engine comprising: a fuel injection valve that injects fuel into the internal combustion engine;
NOx amount estimating means for estimating the amount of NOx generated by combustion based on the operating state of the internal combustion engine;
In-cylinder temperature calculating means for calculating an in-cylinder temperature based on the in-cylinder pressure;
In-cylinder temperature difference amount calculating means for calculating a difference between a reference in-cylinder temperature set based on an operating state of the internal combustion engine and an actual in-cylinder temperature for each operation region of the internal combustion engine;
NOx correction amount calculating means for calculating a NOx correction amount based on the difference;
Estimated NOx amount correcting means for correcting the NOx amount estimated by the NOx amount estimating means by the NOx correction amount;
A control device for an internal combustion engine, comprising: The in-cylinder temperature difference amount calculating means calculates the difference in the operation region at the time of the deceleration fuel cut and the difference in the light load operation region,
The NOx correction amount calculating means calculates a first NOx correction amount from a difference in the operation region at the time of the deceleration fuel cut, and a second NOx correction amount is calculated based on the first NOx correction amount and the difference in the light load operation region. NOx correction amount of
The estimated NOx amount correcting means corrects the NOx amount estimated by the NOx amount estimating means by at least one of the first NOx correction amount and the second NOx correction amount. Item 2. A control device for an internal combustion engine according to Item 1. The in-cylinder temperature difference amount calculating means includes means for calculating a difference in the middle and high load operation region,
The estimated NOx amount correction means includes means for calculating the second NOx correction amount from the difference in the medium-high load operation region instead of the first NOx correction amount and the difference in the light load operation region. The control apparatus for an internal combustion engine according to claim 2. Injection timing determining means for determining the fuel injection timing based on the operating state of the internal combustion engine;
Injection timing advance means for advancing the fuel injection timing determined by the injection timing determination means based on the second NOx correction amount;
The control apparatus for an internal combustion engine according to claim 2 or 3, wherein the estimated NOx amount correcting means corrects the NOx amount estimated by the NOx amount estimating means with the first NOx correction amount.

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