JP2006291828A - Controller and exhaust gas temperature estimating method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller and an exhaust gas temperature estimating method for an internal combustion engine capable of accurately estimating an exhaust gas temperature. <P>SOLUTION: This controller for the internal combustion engine calculates the estimated value of a first exhaust gas temperature (exhaust gas temperature at an engine body 11) by using a rounded value set based on a fuel injection amount and an air suction amount, and the estimated value of a second exhaust gas temperature (exhaust gas temperature on the upstream side of an NOx catalytic converter 72) based on the estimated value of the first exhaust gas temperature. Furthermore, the controller determines whether it performs a temperature raising control treatment or not based on the catalyst floor temperature of the NOx catalytic converter 72 estimated through the estimated value of the second exhaust gas temperature in a PM regenerative control. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that calculates an estimated value of an exhaust temperature and performs engine control using the estimated value, and an exhaust temperature estimation method for an internal combustion engine that estimates an exhaust temperature.

As a control device for the internal combustion engine, for example, a control device that performs control (PM regeneration control) for purifying particulate matter in a diesel engine is known. The control device estimates the temperature of the catalyst device and the PM filter based on the estimated value of the exhaust temperature, and executes PM regeneration control using the estimated temperature. For example, a control device described in Patent Document 1 is known as a control device that executes PM regeneration control.
JP 2004-143988 A

By the way, the above control device is required to accurately estimate the output exhaust temperature in order to avoid problems such as PM regeneration failure.
Accordingly, the present inventor constructs a heat exchange model that simulates heat exchange between the exhaust and the exhaust system, and applies the estimated value of the exhaust temperature in the engine body to the heat exchange model to estimate the exhaust temperature. As a result, the estimation accuracy of the exhaust temperature was improved.

  However, when the estimated value calculated through the heat exchange model was compared with the actual exhaust temperature, it was confirmed that the estimated value and the measured value might be greatly different. In addition, if it is a control apparatus of the internal combustion engine which performs engine control using the estimated value of exhaust gas temperature, it is requested | required that the estimation accuracy of exhaust gas temperature should be raised like the control apparatus of the diesel engine.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an internal combustion engine control apparatus and an internal combustion engine exhaust temperature estimation method capable of accurately estimating the exhaust gas temperature. .

In the following, means for achieving the above object and its effects are described.
<Claim 1>
According to the first aspect of the present invention, an engine control means for performing engine control using the exhaust temperature as a parameter, an exhaust temperature at the engine body or an exhaust temperature corresponding to the temperature as an input exhaust temperature, and an estimated value of the input exhaust temperature is obtained. An internal combustion engine comprising: an input temperature estimating means for calculating; and an output temperature estimating means for calculating an estimated value of the output exhaust temperature based on the estimated value of the input exhaust temperature, using the exhaust temperature used for the engine control as an output exhaust temperature. The gist of the present invention is that the engine control device includes an estimation means for calculating an estimated value of the input exhaust gas temperature using an annealing value set with at least one of a fuel injection amount and an intake air amount as a parameter.

The present inventor has confirmed that the input exhaust temperature changes as follows through the test.
(A) When the operation state is switched from the operation state A to the operation state B and the operation state B is continued for a long period of time, the input exhaust temperature is changed to the input exhaust temperature (steady exhaust temperature) suitable for the operation state B with a certain delay. Converge.
(B) The time until the input exhaust temperature converges to the steady exhaust temperature has a correlation with the fuel injection amount and the intake air amount.

  Therefore, as in the first aspect of the present invention, the estimated value of the input exhaust temperature is calculated by using the smoothed value set based on at least one of the fuel injection amount and the intake air amount. The estimation accuracy can be improved. As a result, the exhaust gas temperature can be accurately estimated.

<Claim 2>
According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, the estimating means calculates the estimated value of the input exhaust gas temperature from the following calculation formula.

Y <-Y (n-1) + {Z (n) -Y (n-1)} / X

(A) The “Y” is an estimated value of the input exhaust temperature in the current control cycle. (B) The “Y (n−1)” is an estimated value of the input exhaust temperature calculated in the previous control cycle. (C) “Z (n)” is a reference value of the estimated value of the input exhaust temperature calculated based on the engine operating state of the current control cycle. (D) The “X” is a parameter with at least one of the fuel injection amount and the intake air amount as a parameter. Set annealing value

This is the gist.

<Claim 3>
According to a third aspect of the present invention, in the control device for an internal combustion engine according to the second aspect, the estimating means presets a relationship between at least one of the fuel injection amount and the intake air amount and the smoothing value. The gist is that the “X” is calculated from an arithmetic model.

<Claim 4>
According to a fourth aspect of the present invention, in the control apparatus for an internal combustion engine according to the second or third aspect, the estimating means is configured to calculate the “Z from a calculation model in which a relationship between an engine operating state and the input exhaust gas temperature is set in advance. (N) "is calculated.

<Claim 5>
According to a fifth aspect of the present invention, in the control device for an internal combustion engine according to any one of the first to fourth aspects, the estimation means increases the smoothing value as the fuel injection amount increases. There is a summary.

  The inventor has confirmed the following with respect to changes in the input exhaust gas temperature through the test. That is, as the fuel injection amount increases, the time for the input exhaust temperature to converge to the steady exhaust temperature becomes longer (the input exhaust temperature is less likely to converge to the steady exhaust temperature).

  Therefore, as in the invention described in claim 5, by increasing the smoothing value as the fuel injection amount increases, it is possible to calculate the estimated value of the input exhaust gas temperature and the estimated value of the output exhaust gas temperature more accurately. become able to.

<Claim 6>
According to a sixth aspect of the present invention, in the control device for an internal combustion engine according to any one of the first to fifth aspects, the estimation means decreases the smoothing value as the intake air amount increases. There is a summary.

  The inventor has confirmed the following with respect to changes in the input exhaust gas temperature through the test. That is, as the intake air amount increases, the time for the input exhaust temperature to converge to the steady exhaust temperature becomes shorter (the input exhaust temperature tends to converge to the steady exhaust temperature).

  Therefore, as in the sixth aspect of the invention, the estimated value of the input exhaust gas temperature, and hence the estimated value of the output exhaust gas temperature, can be calculated more accurately by decreasing the smoothing value as the intake air amount increases. become able to.

<Claim 7>
The invention according to claim 7 is the internal combustion engine control apparatus according to any one of claims 1 to 6, wherein the output temperature estimating means simulates heat exchange between the exhaust and the exhaust system. The gist is that the estimated value of the output exhaust gas temperature is calculated by applying the estimated value of the input exhaust gas temperature.

<Claim 8>
The invention according to claim 8 is the control apparatus for an internal combustion engine according to any one of claims 1 to 7, wherein the internal combustion engine includes an additive supply means for supplying the additive into the exhaust, A catalyst device that occludes the nitrogen oxide, and the control device, when a condition for reducing the nitrogen oxide occluded in the catalyst device is satisfied, the additive supply means At least that the estimated value of the temperature of the catalyst device is equal to or higher than a reduction temperature at which the reduction reaction of the nitrogen oxide by the additive can occur. It is included in the conditions, and further, the estimated value of the temperature of the catalyst device is calculated based on the estimated value of the output exhaust gas temperature.

  In an internal combustion engine that performs reduction of nitrogen oxides, when the additive is supplied into the exhaust gas even though the actual temperature of the catalyst device is lower than the reduction temperature, the oxidation reaction of the additive in the catalyst device May cause various problems due to insufficient generation. Therefore, in the control device for the internal combustion engine, in order to make it difficult to cause such a problem, it is required to accurately estimate the temperature of the catalyst device.

  According to the eighth aspect of the invention, the estimated value of the output exhaust gas temperature is calculated based on the estimated value of the input exhaust gas temperature, and the estimated value of the temperature of the catalyst device is calculated based on the estimated value. Thus, the estimation accuracy of the temperature of the catalyst device can be improved.

<Claim 9>
The invention according to claim 9 is the control apparatus for an internal combustion engine according to any one of claims 1 to 8, wherein the internal combustion engine includes an additive supply means for supplying the additive into the exhaust, and the exhaust A catalyst device that occludes the nitrogen oxide, and the control device, when a condition for reducing the sulfur oxide occluded in the catalyst device is satisfied, the additive supply means The process of reducing the sulfur oxide through the supply of the additive by means of, and the supply amount of the additive is set based on the estimated value of the temperature of the catalyst device and the target value of the temperature of the catalyst device Furthermore, the gist is that the estimated value of the temperature of the catalyst device is calculated based on the estimated value of the output exhaust gas temperature.

  In internal combustion engines that reduce sulfur oxides, if the supply amount of the additive is significantly lower than the appropriate value during the process of reducing sulfur oxides, nitrogen oxides are not obtained because sulfur oxides are not sufficiently reduced. There is a risk of reducing the storage capacity of objects. On the other hand, when the supply amount of the additive greatly exceeds an appropriate value, the temperature of the catalyst device becomes excessively high, which may cause damage to the device. Therefore, in the control device for the internal combustion engine, in order to make it difficult to cause such a problem, it is required to accurately estimate the temperature of the catalyst device.

  According to the ninth aspect of the invention, the estimated value of the output exhaust gas temperature is calculated based on the estimated value of the input exhaust gas temperature, and the estimated value of the temperature of the catalyst device is calculated based on the estimated value. Thus, the estimation accuracy of the temperature of the catalyst device can be improved.

<Claim 10>
The invention according to claim 10 is the control apparatus for an internal combustion engine according to any one of claims 1 to 9, wherein the internal combustion engine includes an additive supply means for supplying an additive into the exhaust, and the addition A catalyst device that promotes the oxidation reaction of the agent, and an exhaust filter that is disposed downstream of the catalyst device and captures particulate matter, and the control device includes particles captured by the exhaust filter When the conditions for purifying the particulate matter are satisfied, the particulate matter is purified through the supply of the additive by the additive supply means, and the estimated value of the exhaust filter temperature and the exhaust filter The supply amount of the additive is set based on the target value of temperature, and the estimated value of the temperature of the exhaust filter is calculated based on the estimated value of the output exhaust temperature. It is summarized in that.

  In an internal combustion engine that purifies particulate matter, if the supply amount of the additive is significantly lower than the appropriate value during the process of purifying the particulate matter, the exhaust filter may not be sufficiently purified. There is a risk of clogging. On the other hand, when the supply amount of the additive greatly exceeds an appropriate value, the temperature of the exhaust filter becomes excessively high, which may cause damage to the filter. Therefore, in the control device for the internal combustion engine, in order to make it difficult to cause such a problem, it is required to accurately estimate the temperature of the exhaust filter.

  According to the tenth aspect of the present invention, the estimated value of the output exhaust temperature is calculated based on the estimated value of the input exhaust temperature, and the estimated value of the temperature of the exhaust filter is calculated based on the estimated value. The accuracy of estimating the temperature of the exhaust filter can be improved.

<Claim 11>
According to an eleventh aspect of the present invention, in an internal combustion engine control apparatus that performs engine control using an estimated value of exhaust gas temperature, the smoothing value set based on at least one of a fuel injection amount and an intake air amount is used. The gist is that an estimation means for calculating an estimated value of the exhaust gas temperature is provided.

  As in the invention described in claim 11, the estimated value of the exhaust temperature is also calculated by using the smoothed value set based on at least one of the fuel injection amount and the intake air amount. The effect according to the effect of invention can be show | played.

<Claim 12>
According to the twelfth aspect of the present invention, the exhaust gas temperature in the engine body or the exhaust gas temperature corresponding to the exhaust temperature is used as the input exhaust gas temperature, and the exhaust gas temperature used for engine control is used as the output exhaust gas temperature. In the exhaust gas temperature estimation method of the internal combustion engine for calculating the estimated value of the output exhaust gas temperature based on the estimated value, at least one of the fuel injection amount and the intake air amount is calculated when calculating the estimated value of the input exhaust gas temperature. The gist is to use an annealing value set as a parameter.

  As in the twelfth aspect, the estimated accuracy of the input exhaust temperature is calculated by calculating the estimated value of the input exhaust temperature using the smoothed value set based on at least one of the fuel injection amount and the intake air amount. Is improved. As a result, the exhaust temperature in the exhaust system can be accurately estimated.

<Claim 13>
According to a thirteenth aspect of the present invention, in the exhaust gas temperature estimating method for an internal combustion engine according to the twelfth aspect, the estimated value of the input exhaust gas temperature is calculated from the following equation.

Y <-Y (n-1) + {Z (n) -Y (n-1)} / X

(A) The “Y” is an estimated value of the input exhaust temperature in the current estimation cycle. (B) The “Y (n−1)” is an estimated value of the input exhaust temperature calculated in the previous estimation cycle. (C) “Z (n)” is a reference value of the estimated value of the input exhaust gas temperature calculated based on the engine operating state of the current estimation cycle. (D) “X” is a parameter with at least one of the fuel injection amount and the intake air amount. Set annealing value

This is the gist.

<Claim 14>
A fourteenth aspect of the present invention is the exhaust gas temperature estimating method for an internal combustion engine according to the thirteenth aspect, wherein at least one of the fuel injection amount and the intake air amount and the smoothing value when calculating the “X”. The gist is to use a calculation model in which is set in advance.

<Claim 15>
According to a fifteenth aspect of the present invention, in the exhaust gas temperature estimating method for an internal combustion engine according to the thirteenth or fourteenth aspect, a relationship between the engine operating state and the input exhaust gas temperature is preset when calculating the “Z (n)”. The gist is to use the calculated model.

<Claim 16>
The gist of the invention described in claim 16 is the exhaust temperature estimating method for an internal combustion engine according to any one of claims 12 to 15, wherein the smoothing value is increased as the fuel injection amount increases. .

  As in the sixteenth aspect of the present invention, by increasing the smoothing value as the fuel injection amount increases, it is possible to calculate the estimated value of the input exhaust gas temperature and the estimated value of the output exhaust gas temperature with higher accuracy. become.

<Claim 17>
The gist of the invention described in claim 17 is that, in the exhaust temperature estimation method for an internal combustion engine according to any one of claims 12 to 16, the smoothing value is decreased as the intake air amount increases. .

  As in the seventeenth aspect of the present invention, the estimated value of the input exhaust gas temperature and thus the estimated value of the output exhaust gas temperature can be calculated with higher accuracy by decreasing the smoothing value as the intake air amount increases. become.

An embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the case where this invention is actualized as a control apparatus of a diesel engine is assumed.

<Diesel engine structure>
FIG. 1 shows a schematic structure of a diesel engine to which the present invention is applied.
The diesel engine 1 includes an engine body 11, a turbocharger 4, a common rail fuel supply device 5, an exhaust gas recirculation device 6, and an exhaust gas purification device 7. Various devices are controlled through the electronic control device 9.

The engine body 11 is provided with a plurality of cylinders 12.
A combustion chamber 13 for burning a mixture of air and fuel is formed in the cylinder 12.

  In the diesel engine 1, an intake passage 23 through which external air is circulated into the combustion chamber 13 is configured by the intake port of the engine body 11, the intake manifold 21, and the intake pipe 22.

  In the intake passage 23, an air cleaner 24, a compressor wheel 41 of the turbocharger 4, an intercooler 25, and a throttle valve 26 are arranged in this order from the upstream side in the air flow direction.

  In the diesel engine 1, an exhaust passage 33 through which the gas in the combustion chamber 13 circulates to the outside is configured by the exhaust port of the engine body 11, the exhaust manifold 31, and the exhaust pipe 32.

  In the exhaust passage 33, the fuel addition valve 71 of the exhaust purification device 7, the turbine wheel 42 of the turbocharger 4, the NOx catalytic converter 72 of the exhaust purification device 7, and the catalyst-carrying PM filter 73 are arranged in this order from the upstream side in the exhaust flow direction. Is arranged. In the present embodiment, the fuel addition valve 71 corresponds to the additive supply means. The NOx catalytic converter 72 corresponds to a catalyst device. The catalyst-carrying PM filter 73 corresponds to an exhaust filter.

[1] “Structure of turbocharger”
The turbocharger 4 increases the amount of air supplied into the combustion chamber 13 by compressing the air in the intake pipe 22 using the energy of the exhaust.

  The turbocharger 4 includes a compressor wheel 41 disposed in the intake passage 23, a turbine wheel 42 disposed in the exhaust passage 33, and a rotor shaft 43 connecting these wheels 41, 42. The intake air is compressed by rotating the compressor wheel 41 together with the turbine wheel 42 through the energy of the exhaust.

[2] “Structure of common rail fuel supply system”
The common rail fuel supply device 5 burns fuel in the combustion chamber 13 by injecting high-pressure fuel into the combustion chamber 13.

The common rail fuel supply device 5 includes a fuel injection valve 51, a fuel tank 52, a fuel pump 53, and a common rail 54.
The fuel injection valve 51 injects fuel into the combustion chamber of the corresponding cylinder 12.

The fuel pump 53 sucks the fuel in the fuel tank 52, pressurizes the sucked fuel to a predetermined pressure, and supplies it to the common rail 54.
The common rail 54 maintains the fuel supplied from the fuel pump 53 in a high pressure state. The fuel in the common rail 54 is injected from the fuel injection valve 51 into the combustion chamber of the cylinder 12 as each fuel injection valve 51 is opened.

[3] “Structure of exhaust gas recirculation device”
The exhaust gas recirculation device 6 supplies a part of the exhaust gas into the intake pipe 22, thereby lowering the combustion temperature of the air-fuel mixture and reducing the generation amount of nitrogen oxides (NOx).

The exhaust gas recirculation device 6 includes a communication pipe 61, an EGR cooler 62, and an EGR valve 63.
The communication pipe 61 communicates the exhaust passage 33 upstream of the turbine wheel 42 and the intake passage 23 downstream of the throttle valve 26. Further, an EGR cooler 62 and an EGR valve 63 are arranged in the communication pipe 61 in order from the upstream side in the exhaust flow direction.

The EGR cooler 62 cools the exhaust gas supplied to the intake pipe 22 via the communication pipe 61.
The EGR valve 63 adjusts the flow rate of exhaust gas supplied to the intake pipe 22 via the communication pipe 61.

[4] “Structure of exhaust emission control device”
The exhaust purification device 7 purifies particulate matter (PM), nitrogen oxides (NOx), hydrocarbons (HC) and carbon monoxide (CO) in the exhaust.

The exhaust purification device 7 includes a fuel addition valve 71, a NOx catalytic converter 72, and a catalyst-carrying PM filter 73.
The NOx catalytic converter 72 includes a catalyst carrier on which an NOx storage reduction catalyst is supported.

In the NOx catalytic converter 72, NOx purification is performed as follows.
(A) When the exhaust is in an oxidizing atmosphere (lean), NOx in the exhaust is stored in the NOx catalyst.
(B) When the exhaust is in a reducing atmosphere (stoichiometric or rich), NOx stored in the NOx catalyst is released as nitrogen monoxide (NO) and is reduced by HC or CO.

  “Stoichi” is the state where the air-fuel ratio of the exhaust corresponds to the stoichiometric air-fuel ratio, “Lean” is the state where the air-fuel ratio of the exhaust is larger than the stoichiometric air-fuel ratio, “Rich” is the state where the air-fuel ratio of the exhaust is the stoichiometric air-fuel ratio Each smaller state is shown.

  The catalyst-carrying PM filter 73 includes a porous ceramic structure (PM filter) that can capture PM in the exhaust gas. The PM filter carries a NOx storage reduction catalyst.

In the catalyst-carrying PM filter 73, PM is captured and purified as follows.
(A) When exhaust passes through the wall of the porous ceramic structure, PM in the exhaust is captured by the wall of the ceramic structure.
(B) When the exhaust gas is hot, the trapped PM is oxidized by oxygen in the exhaust gas.
(C) The trapped PM is oxidized by active oxygen generated during NOx storage and release.

The catalyst-carrying PM filter 73 purifies NOx in the same manner as the NOx catalytic converter 72.
The fuel addition valve 71 adds fuel into the exhaust through injection of fuel (additive). The fuel addition valve 71 is supplied with fuel having a lower pressure than the fuel supplied to the common rail 54 through the fuel pump 53.

  The fuel injected from the fuel addition valve 71 is supplied to the NOx catalytic converter 72 and the catalyst-carrying PM filter 73 together with the exhaust gas. In the diesel engine 1, fuel injection (fuel addition) is performed by the fuel addition valve 71 for the purpose of supplying fuel to the NOx catalytic converter 72 and the catalyst-carrying PM filter 73. Details of the fuel addition mode by the fuel addition valve 71 will be described later.

[5] "Control system structure"
The electronic control unit 9 temporarily stores a central processing unit that executes arithmetic processing related to engine control, a read-only memory in which programs and maps necessary for engine control are stored in advance, calculation results of the central processing unit, etc. A random access memory, an input port for inputting an external signal, an output port for outputting a signal to the outside, and the like.

  A rotation speed sensor 91, a cooling water temperature sensor 92, an air flow meter 93, an intake air temperature sensor 94, an atmospheric pressure sensor 95, and the like for detecting the engine operating state are connected to the input port of the electronic control unit 9.

  The rotational speed sensor 91 is provided in the vicinity of the crankshaft, and outputs an electrical signal corresponding to the rotational speed of the crankshaft (engine rotational speed NE). The output signal of the rotation speed sensor 91 is input to the electronic control unit 9 and then used as various engine rotation speed measurement values NEM for various controls.

  The cooling water temperature sensor 92 is provided around the cylinder 12 and outputs an electrical signal corresponding to the temperature of the cooling water in the water jacket (cooling water temperature THW). The output signal of the cooling water temperature sensor 92 is input to the electronic control unit 9 and then used for various controls as the cooling water temperature measurement value THWM.

  The air flow meter 93 is provided in the intake passage 23 downstream of the air cleaner 16 and upstream of the compressor wheel 41, and outputs an electrical signal corresponding to the flow rate of air flowing through the intake pipe 22 (intake air amount GA). After the output signal of the air flow meter 93 is input to the electronic control unit 9, it is used for various controls as an intake air amount measurement value GAM.

  The intake air temperature sensor 94 is provided in the intake passage 23 downstream of the air cleaner 16 and upstream of the compressor wheel 41, and outputs an electrical signal corresponding to the temperature of the air flowing through the intake pipe 22 (intake air temperature THA). The output signal of the intake air temperature sensor 94 is input to the electronic control unit 9, and then used as various measured values as the intake air temperature measurement value THAM.

  The atmospheric pressure sensor 95 is provided in the intake passage 23 in the vicinity of the air cleaner 16 and outputs an electrical signal corresponding to the atmospheric pressure (atmospheric pressure FPA). The output signal of the atmospheric pressure sensor 95 is input to the electronic control unit 9, and then used as various atmospheric pressure measurement values FPAM for various controls.

Drive circuits such as the throttle valve 26, the EGR valve 63, the fuel pump 53, the fuel injection valve 51, and the fuel addition valve 71 are connected to the output port of the electronic control unit 9.
The electronic control unit 9 determines the required value of each control parameter (for example, the fuel injection amount (fuel injection amount FI) by the fuel injection valve 51 or the fuel addition valve) based on the engine operation state grasped from the detection signal of each sensor. The fuel addition amount by 71 (fuel addition amount FA)) is set. Then, a command signal corresponding to the required value is output to the drive circuit of each device connected to the output port.

  The electronic control device 9 controls the drive circuit so that the throttle control for adjusting the opening of the throttle valve 26, the EGR control for adjusting the opening of the EGR valve 63, the discharge pressure control for adjusting the discharge pressure of the fuel pump 53, Various controls such as fuel injection control for injecting fuel from the fuel injection valve 51 and fuel addition control for injecting fuel from the fuel addition valve 71 are performed. Note that the control means includes the electronic control device 9.

<Exhaust gas purification control>
In this embodiment, as control for purifying exhaust, “PM regeneration control” for burning PM on the catalyst-carrying PM filter 73, and reducing and releasing sulfur oxide (SOx) stored in the NOx catalyst. “S poisoning recovery control” to be performed and “NOx reduction control” to reduce and release NOx stored in the NOx catalyst are performed.

  In order to perform PM regeneration that burns PM and S poison recovery that reduces and releases SOx, it is necessary to sufficiently raise the temperature (catalyst bed temperature) of the NOx catalytic converter 72 and the catalyst-carrying PM filter 73. Therefore, in PM regeneration control and S poison recovery control, temperature increase control is performed to increase the catalyst bed temperature to a temperature (for example, 600 to 700 ° C.) required for PM regeneration and S poison recovery.

  In the temperature raising control, fuel supply to the exhaust gas by the fuel addition valve 71 is continuously repeated at relatively short intervals to increase the amount of fuel supplied to the NOx catalyst (NOx catalyst converter 72 and catalyst-carrying PM filter 73). I try to let them. As a result, the catalyst bed temperature can be increased due to heat generated by the oxidation reaction of the fuel in the exhaust gas or on the catalyst.

[1] "PM regeneration control"
In the exhaust purification device 7, the pressure loss in the PM filter 73 increases as the amount of PM trapped in the catalyst-carrying PM filter 73 increases. Therefore, it is necessary to purify the PM accumulated on the filter before the pressure loss increases to such a degree as to deteriorate the engine operating condition.

Therefore, when it is estimated that the amount of PM accumulated on the catalyst-carrying PM filter 73 has reached the limit value, the electronic control unit 9 performs temperature increase control through PM regeneration control.
Since high-temperature exhaust gas is supplied to the catalyst-carrying PM filter 73 by the oxidation reaction of fuel in the NOx catalytic converter 72, PM is combusted through the high temperature of the catalyst-carrying PM filter 73. Further, since the fuel that has passed through the NOx catalytic converter 72 is oxidized by the catalyst-carrying PM filter 73, PM is combusted through heat generated by the oxidation reaction.

[2] "S poison recovery control"
The NOx catalyst of the NOx catalytic converter 72 and the catalyst-carrying PM filter 73 has the property of absorbing SOx generated from the sulfur content derived from fuel and lubricating oil together with NOx. On the other hand, since the storage amount of the NOx catalyst has a limit, when the SOx storage amount becomes excessively large, the NOx storage capacity is reduced (S poisoning). Therefore, the exhaust purification device 7 needs to reduce the SOx stored in the NOx catalyst before it interferes with NOx storage due to an increase in the SOx storage amount.

Therefore, when it is estimated that the amount of SOx occluded in the NOx catalyst has reached the limit value, the electronic control device 9 performs the temperature rise control and the SOx reduction control through the S poison recovery control.
As a result, after the NOx catalytic converter 72 and the catalyst-carrying PM filter 73 are heated through the temperature rise control, the exhaust air-fuel ratio is made rich through the SOx reduction control. The periphery of 73 is maintained in a high-temperature reducing atmosphere. Then, the SOx stored in the NOx catalyst is reduced and then released from the NOx catalyst.

[3] "NOx reduction control"
In the exhaust purification device 7, it is necessary to reduce and release the NOx stored in the NOx catalyst before the NOx storage amount of the NOx catalytic converter 72 and the catalyst-carrying PM filter 73 reaches the limit.

  Therefore, when it is estimated that the amount of NOx stored in the NOx catalyst has reached the limit value, the electronic control device 9 performs intermittent fuel addition by the fuel addition valve 71 through NOx reduction control.

  As a result, the air-fuel ratio of the exhaust gas surrounding the NOx catalyst is temporarily stoichiometric or rich, so that NOx in the NOx catalytic converter 72 and the catalyst-carrying PM filter 73 is reduced. During NOx reduction control, the catalyst bed temperature is maintained at a relatively low temperature (for example, 250 to 500 ° C.).

  Note that after-injection by the fuel injection valve 51 can be performed as necessary during the temperature increase control during the execution of the PM regeneration control and the S poison recovery control. This after injection is fuel injection executed during the compression stroke and exhaust stroke after the pilot injection and the main injection are performed, and is used for combustion in the combustion chamber 13 such as pilot injection and main injection. The fuel injection is different from the fuel injection. As a result, most of the fuel injected in the after injection is discharged into the exhaust system without being combusted in the combustion chamber 13, so that the amount of fuel in the exhaust is increased and the catalyst bed temperature is increased.

<PM regeneration control processing>
The “PM regeneration control process” will be described with reference to FIG. This process is repeatedly executed by the electronic control device 9 at regular intervals. Further, this processing corresponds to processing executed through the engine control means. In the following description, the converter catalyst bed temperature TC is the catalyst bed temperature of the NOx catalyst converter 72, the filter catalyst bed temperature TF is the catalyst bed temperature of the catalyst-carrying PM filter 73, and the target catalyst bed temperature TFT is the temperature rise control. The target values of the filter catalyst bed temperature TF are respectively shown.

[Step S110] It is determined whether or not “temperature increase control processing” (FIG. 3) for increasing the filter catalyst bed temperature TF to the target catalyst bed temperature TFT is being executed.
When the “temperature increase control process” is not executed, the process of step S120 is performed.
When the “temperature increase control process” is being executed, the process of step S130 is performed.

[Step S120] It is determined whether an execution condition (condition for purifying PM) of PM regeneration control is satisfied.
When the execution condition is satisfied, the process of step S122 is performed.
When the execution condition is not satisfied, the “PM regeneration control process” is temporarily terminated.

In the process of step S120, for example, it can be determined that the execution condition for PM regeneration control is satisfied when the following conditions [a] and [b] are satisfied.
[A] The amount of PM deposited on the catalyst-carrying PM filter 73 (PM accumulation amount) has reached a limit value.
[B] The estimated value of the converter catalyst bed temperature TC (estimated converter catalyst bed temperature TCE) is equal to or higher than the lower limit temperature TClmt required for causing the fuel oxidation reaction. The estimated converter catalyst bed temperature TCE is calculated through the “exhaust temperature estimation process” (FIGS. 4 and 5). Further, it is calculated as a value representative of the catalyst bed temperature of the NOx catalytic converter 72.

In the process of step S120, for example, it can be determined that the PM deposition amount has reached the limit value when either of the following conditions [c] and [d] is satisfied.
[C] The PM accumulation amount estimated based on the operation history (intake air amount and fuel injection amount) of the diesel engine 1 is greater than or equal to a predetermined value.
[D] The degree of deviation between the measured value of the pressure upstream of the catalyst-carrying PM filter 73 and the measured value of the downstream pressure is larger than a predetermined degree.

  [Step S122] The “temperature increase control process” (FIG. 3) is started. As a result, in the next control cycle of the “PM regeneration control process”, the process proceeds from step S110 to step S130.

[Step S130] It is determined whether a PM regeneration control end condition is satisfied.
When the end condition is satisfied, the process of step S132 is performed.
When the termination condition is not satisfied, the “PM regeneration control process” is temporarily terminated.

In the process of step S130, for example, it can be determined that the PM regeneration control end condition is satisfied when one of the following conditions [a] and [b] is satisfied.
[A] The PM accumulation amount estimated based on the operation history (intake air amount and fuel injection amount) of the diesel engine 1 is equal to or less than the initial value.
[B] The degree of deviation between the measured value of the upstream pressure of the catalyst-carrying PM filter 73 and the measured value of the downstream pressure is smaller than a predetermined degree.

  In the exhaust purification device 7 of the present embodiment, the period from when the execution condition for PM regeneration control is satisfied to when the end condition for PM regeneration control is satisfied corresponds to the execution of PM regeneration control. That is, the period of synchronization corresponds to one cycle of PM regeneration control.

  [Step S132] The “temperature increase control process” (FIG. 3) is terminated. Note that the execution condition and end condition of the PM regeneration control are not limited to the contents exemplified above, and can be changed as appropriate.

<Temperature control process>
The “temperature increase control process” will be described with reference to FIG. This process is repeatedly executed at regular intervals by the electronic control device 9 from when the execution condition for PM regeneration control is satisfied until the end condition for PM regeneration control is satisfied.

[Step S210] It is determined whether or not the target catalyst bed temperature TFT has been set after the “temperature increase control process” is started through the “PM regeneration control process”.
When the target catalyst bed temperature TFT is not set, the process of step S212 is performed.
When the target catalyst bed temperature TFT is set, the process of step S214 is performed.

  [Step S212] The target catalyst bed temperature TFT is calculated based on the engine operating state (for example, the engine rotation speed measurement value NEM and the fuel injection amount FI). Here, the target catalyst bed temperature TFT is calculated from a map in which the relationship between the engine operating state and the target catalyst bed temperature TFT is set in advance.

  The target catalyst bed temperature TFT is set as a temperature higher than the minimum catalyst bed temperature required for burning the PM on the catalyst-carrying PM filter 73 when the NOx catalyst converter 72 is normal. Accordingly, when the NOx catalytic converter 72 is normal, the filter catalyst bed temperature TF is maintained at the target catalyst bed temperature TFT through the “temperature rise control process”, so that the accumulated PM is sufficiently combusted.

  [Step S214] Based on the target catalyst bed temperature TFT, the amount of fuel added to the exhaust by the fuel addition valve 71 (fuel addition amount FA) is set. Here, it is necessary to maintain the filter catalyst bed temperature TF at the target catalyst bed temperature TFT based on the difference between the target catalyst bed temperature TFT and the estimated value of the filter catalyst bed temperature TF (estimated filter catalyst bed temperature TFE). A fuel addition amount FA is calculated. The estimated filter catalyst bed temperature TFE is calculated through “exhaust temperature estimation process” (FIGS. 4 and 5). Further, it is calculated as a value representative of the catalyst bed temperature of the catalyst-carrying type PM filter 73.

  In the fuel addition control separately executed in the electronic control unit 9, the addition valve 71 is controlled so that fuel of the same addition amount FA is injected from the fuel addition valve 71 every time the fuel addition amount FA is set through this step S214. To do. Thus, the fuel addition by the fuel addition valve 71 is repeatedly executed, so that the filter catalyst bed temperature TF is maintained at the target catalyst bed temperature TFT (or a nearby temperature).

<Exhaust temperature estimation process>
This process includes the following “first estimation process”, “second estimation process”, and “third estimation process”.

  (A) In the “first estimation process”, an exhaust temperature (first exhaust temperature TEA (input exhaust temperature)) in the engine body 11 is estimated. As the input exhaust temperature, an exhaust temperature corresponding to the exhaust temperature in the engine body 11 (for example, an exhaust temperature before heat exchange is performed in the exhaust system) may be employed.

  (B) In the “second estimation process”, the exhaust temperature (second exhaust temperature TEB (output) after heat exchange with the exhaust system is performed in the exhaust passage 33 downstream of the turbocharger 4 and upstream of the NOx catalytic converter 72. Estimate the exhaust temperature)).

  (C) In the “third estimation process”, the exhaust temperature (third exhaust temperature) after heat exchange with the exhaust system is performed in the exhaust passage 33 downstream of the NOx catalytic converter 72 and upstream of the catalyst-carrying PM filter 73. TEC (output exhaust temperature)) is estimated.

In the following, the estimated values of the exhaust temperatures calculated through this process are shown as follows.
The estimated value of the first exhaust temperature TEA is set as a first exhaust temperature estimated value eTEA.
The estimated value of the second exhaust temperature TEB is taken as the second exhaust temperature estimated value eTEB.
The estimated value of the third exhaust temperature TEC is taken as the third exhaust temperature estimated value eTEC.

  A detailed processing procedure of the “exhaust temperature estimation process” will be described with reference to FIGS. 4 and 5. This process is repeatedly executed by the electronic control device 9 at regular intervals. The “exhaust temperature estimation process” includes a process executed through the input temperature estimation means, a process executed through the output temperature estimation means, and a process executed through the estimation means.

  In this process, the process in step S312 corresponds to a “first estimation process”, the process in step S320 corresponds to a “second estimation process”, and the process in step S330 corresponds to a “third estimation process”.

  [Step S302] A steady exhaust temperature TEAbase is calculated based on the engine operating state (fuel injection amount FI and intake air amount GA) in the current control cycle. Here, the steady exhaust temperature TEAbase (reference value for the estimated value of the input exhaust temperature) is calculated by applying the fuel injection amount FI and the intake air amount measurement value GAM to the steady exhaust temperature calculation map (FIG. 6).

  In the diesel engine 1, the fuel supply mode is switched according to execution of “PM regeneration control”, “S poisoning recovery control”, and the like. Since the combustion state of the air-fuel mixture varies depending on each fuel supply mode, a steady exhaust temperature calculation map is set in the electronic control unit 9 for each fuel supply mode. When calculating the steady exhaust temperature TEAbase in the process of step S302, a map corresponding to the fuel supply mode of the current control cycle is selected.

  The steady exhaust temperature TEAbase corresponds to the first exhaust temperature TEA obtained under a steady operation state (a state in which the diesel engine 1 is operated for a long time under the same fuel injection amount FI and intake air amount GA). To do. That is, the first exhaust when the diesel engine 1 is operated for a long period of time while maintaining the fuel injection amount FI and the intake air amount GA at the fuel injection amount FI and the intake air amount GA in the current control cycle through the process of step S302. A steady exhaust temperature TEAbase is calculated as the temperature TEA.

  The steady exhaust temperature calculation map (FIG. 6) is configured by grasping in advance the relationship between the fuel injection amount FI and the intake air amount GA and the steady exhaust temperature TEAbase through a test. The following (a) and (b) show the relationship between each parameter and the steady exhaust temperature TEAbase.

  (A) The steady exhaust temperature TEAbase shows a tendency to change according to the fuel injection amount FI, and basically changes to a higher temperature side as the fuel injection amount FI increases. In the map, the relationship between the fuel injection amount FI and the steady exhaust temperature TEAbase is set in accordance with such a change tendency of the steady exhaust temperature TEAbase.

  (B) The steady exhaust temperature TEAbase shows a tendency to change according to the intake air amount GA, and basically changes to a higher temperature side as the intake air amount GA increases. In the map, the relationship between the intake air amount GA and the steady exhaust temperature TEAbase is set in accordance with the change tendency of the steady exhaust temperature TEAbase. In the present embodiment, the intake air amount GA is adopted as a parameter for calculating the steady exhaust temperature TEAbase, but the engine speed NE can also be adopted as an index value of the intake air amount GA.

  [Step S304] In order to correct the steady exhaust temperature TEAbase according to the difference between the measured value of the air flow meter 93 (measured value of intake air amount GAM) and the amount of intake air supplied to the combustion chamber 13 (supply intake air amount GAR). The intake air correction coefficient GM is calculated.

  In the process of step S304, a ratio (intake ratio GN) between the measured intake air amount GAM and the supplied intake air amount GAR is calculated. Then, the intake correction coefficient GM is calculated from a map in which the relationship between the intake ratio GN and the intake correction coefficient GM is set in advance. The supply intake air amount GAR can be calculated as follows, for example. In other words, the corrected value considering the flow rate of EGR gas, the degree of supercharging by the turbocharger 4 and the like can be applied to the measured intake air amount GAM, and the corrected value can be used as the supplied intake air amount GAR.

  [Step S306] Various correction amounts for correcting the deviation between the steady exhaust temperature TEAbase and the actual first exhaust temperature TEA due to the difference between the reference engine operating environment and the actual engine operating environment are calculated. Here, the following correction amounts (A) to (C) are calculated. The standard engine operating environment corresponds to the engine operating environment when the steady exhaust temperature calculation map (FIG. 6) is constructed.

(A) “Water temperature correction amount TEthw”
The water temperature correction amount TEthw is calculated as a value for correcting a deviation between the steady exhaust temperature TEAbase and the actual first exhaust temperature TEA due to the difference between the coolant temperature THW and the actual coolant temperature THW in the reference engine operating environment. .

  In the process of step S306, the coolant temperature measurement value THWM is applied to a map in which the relationship between the coolant temperature THW and the coolant temperature correction amount TEthw is set in advance to calculate the coolant temperature correction amount TEthw. Incidentally, the first exhaust temperature TEA shows a tendency to change according to the cooling water temperature THW, and basically changes to the low temperature side as the cooling water temperature THW decreases. In the map, the relationship between the cooling water temperature THW and the water temperature correction amount TEthw is set in accordance with such a change tendency of the first exhaust temperature TEA.

(B) “Intake temperature correction amount TEtha”
The intake air temperature correction amount TEtha is calculated as a value for correcting a difference between the steady exhaust temperature TEAbase and the actual first exhaust temperature TEA due to the difference between the intake air temperature THA and the actual intake air temperature THA in the reference engine operating environment.

  In the process of step S306, the intake air temperature correction amount TEtha is calculated by applying the intake air temperature measurement value THAM to a map in which the relationship between the intake air temperature THA and the intake air temperature correction amount TEtha is set in advance. Incidentally, the first exhaust temperature TEA shows a tendency to change according to the intake air temperature THA, and basically changes to a low temperature side as the intake air temperature THA decreases. In the map, the relationship between the intake air temperature THA and the intake air temperature correction amount TEtha is set in accordance with such a change tendency of the first exhaust gas temperature TEA.

(C) “Atmospheric pressure correction amount TEfpa”
The atmospheric pressure correction amount TEfpa is calculated as a value for correcting a deviation between the steady exhaust temperature TEAbase and the actual first exhaust temperature TEA due to the difference between the atmospheric pressure FPA in the reference engine operating environment and the actual atmospheric pressure FPA.

  In the process of step S306, the atmospheric pressure correction amount TEfpa is calculated by applying the atmospheric pressure measurement value FPAM to a map in which the relationship between the atmospheric pressure FPA and the atmospheric pressure correction amount TEfpa is set in advance. Incidentally, the first exhaust temperature TEA shows a tendency to change according to the atmospheric pressure FPA, and basically changes to a higher temperature side as the atmospheric pressure FPA decreases. In the map, the relationship between the atmospheric pressure FPA and the atmospheric pressure correction amount TEfpa is set in accordance with such a change tendency of the first exhaust temperature TEA.

[Step S308] The steady exhaust temperature TEAbase is corrected through the intake correction coefficient GM and the above correction amounts, and the corrected value is set as the environment corrected exhaust temperature TEeng. That is, the environment corrected exhaust temperature TEeng is calculated by the following [Equation 1].

[Formula 1]

TEeng ←

(TEAbase-THAM) x GM

+ THAM + TEthw + TEtha + TEfpa

In the above [Equation 1], the water temperature correction amount TEthw, the intake air temperature correction amount TEtha, and the atmospheric pressure correction amount TEfpa are used as correction amounts according to the engine operating environment. The environment-corrected exhaust temperature TEeng can also be calculated using a backpressure correction amount set according to the engine backpressure).

  [Step S310] The smoothing value SM is set based on the fuel injection amount FI and the intake air amount GA. Here, the smoothing value SM is calculated by applying the fuel injection amount FI and the intake air amount measurement value GAM to the smoothing value calculation map (FIG. 7).

  In the present embodiment, an annealing value calculation map is set based on a change mode of the first exhaust temperature TEA confirmed through a test by the present inventor. In the following [1] “Change Mode of the First Exhaust Temperature TEA”, items that serve as a basis for setting the annealing value calculation map will be described. In addition, in the following [2] “Mode of setting the smoothing value calculation map”, the mode of setting the smoothing value calculation map based on the matter of [1] will be described.

[1] “Change mode of first exhaust temperature TEA”
The present inventor has confirmed the following items (A) to (D) regarding the change mode of the first exhaust temperature TEA accompanying the change of the engine operating state through the test.

  (A) When the intake air amount GA is made constant and the fuel injection amount FI is changed from the previous fuel injection amount FIA to the current fuel injection amount FIB, the first exhaust temperature TEA changes to the previous fuel injection amount FIA with a certain response delay. The transition from the adapted steady exhaust temperature TEAbase (previous steady temperature TEAbaseA) to the steady exhaust temperature TEAbase (current steady temperature TEAbaseB) adapted to the current fuel injection amount FIB.

  The previous steady temperature TEAbaseA corresponds to the steady exhaust temperature TEAbase obtained by applying the previous fuel injection amount FIA and the intake air amount GA to the steady exhaust temperature calculation map. The current steady temperature TEAbaseB corresponds to the steady exhaust temperature TEAbase obtained by applying the current fuel injection amount FIA and the intake air amount GA to the steady exhaust temperature calculation map.

  (B) In the situation of (A) above, the degree of response delay of the first exhaust temperature TEA (the time (delay time) until the first exhaust temperature TEA reaches the current steady temperature TEAbaseB from the previous steady temperature TEAbaseA) is: It has a correlation with the fuel injection amount FI.

  (C) When the fuel injection amount FI is made constant and the intake air amount GA is changed from the previous intake air amount GAC to the current intake air amount GAD, the first exhaust temperature TEA changes to the previous intake air amount GAC with a certain response delay. The transition from the adapted steady exhaust temperature TEAbase (previous steady temperature TEAbaseC) to the steady exhaust temperature TEAbase (current steady temperature TEAbaseD) adapted to the current intake air amount GAD.

  The previous steady temperature TEAbaseC corresponds to the steady exhaust temperature TEAbase obtained by applying the previous intake air amount GAC and the fuel injection amount FI to the steady exhaust temperature calculation map. The current steady temperature TEAbaseD corresponds to the steady exhaust temperature TEAbase obtained by applying the current intake air amount GAD and the fuel injection amount FI to the steady exhaust temperature calculation map.

  (D) In the situation of (C), the degree of response delay of the first exhaust temperature TEA (the time (delay time) until the first exhaust temperature TEA reaches the current steady temperature TEAbaseD from the previous steady temperature TEAbaseC) is: It has a correlation with the intake air amount GA.

[2] “Setting mode of annealing value calculation map”
The delay time when the fuel injection amount FI changes while the intake air amount GA is constant shows a tendency to increase as the fuel injection amount FI increases. In the annealing value calculation map, the relationship between the fuel injection amount FI and the annealing value SM is set in accordance with the degree of response delay of the first exhaust temperature TEA. That is, the map is configured such that the smoothing value SM increases as the fuel injection amount FI changes to the increase side.

  The delay time when the intake air amount GA changes while the fuel injection amount FI is constant shows a tendency to become shorter as the intake air amount GA increases. In the annealing value calculation map, the relationship between the intake air amount GA and the annealing value SM is set in accordance with the degree of response delay of the first exhaust temperature TEA. That is, the map is configured such that the smoothed value SM decreases as the intake air amount GA changes to the increase side.

[Step S312] Based on the difference between the first exhaust temperature estimated value eTEA calculated in the previous control cycle and the environment corrected exhaust temperature TEeng calculated in the current control cycle and the smoothing value SM, An increase amount of the exhaust temperature TEA is calculated. Then, the first exhaust temperature estimated value eTEA in the current control cycle is calculated by adding this temperature rise amount to the first exhaust temperature estimated value eTEA in the previous control cycle. That is, the first exhaust temperature estimated value eTEA is calculated by the following [Equation 2].

[Formula 2]

eTEA ← eTEA (n-1)

+ {TEeng (n) −eTEA (n−1)} / SM

In the above [Formula 2], each term shows the following value.
“TEeng (n)”: Environment corrected exhaust temperature of the current control cycle.
“ETEA (n−1)”: the first estimated exhaust gas temperature value in the previous control cycle.

[Step S320] The first exhaust temperature estimated value eTEA is input to the heat exchange model to calculate the second exhaust temperature estimated value eTEB.
In the heat exchange model, heat exchange between the exhaust system and the exhaust can be simulated based on the heat capacity and heat dissipation characteristics of the exhaust system. In the present embodiment, a heat exchange model is constructed based on an exhaust system constituted by the exhaust manifold 31, the exhaust pipe 32, the turbocharger 4, the exhaust gas recirculation device 6, and the exhaust gas purification device 7. That is, the model is constructed in such a way that the exhaust port of the engine body 11 is not included in the exhaust system.

  [Step S322] An estimated value of the catalyst bed temperature of the NOx catalytic converter 72 (estimated converter catalyst bed temperature TCE) is calculated based on the second estimated exhaust gas temperature value eTEB. Here, the estimated converter catalyst bed temperature TCE is calculated by correcting the second exhaust temperature estimated value eTEB in consideration of the exhaust flow rate, the heat capacity of the NOx catalytic converter 72, the fuel addition amount FA, and the like.

[Step S330] The first exhaust temperature estimated value eTEA is input to the heat exchange model to calculate the third exhaust temperature estimated value eTEC.
[Step S332] An estimated value of the catalyst bed temperature of the catalyst-carrying PM filter 73 (estimated filter catalyst bed temperature TFE) is calculated based on the third estimated exhaust gas temperature value eTEC. Here, the estimated filter catalyst bed temperature TFE is calculated by correcting the third exhaust temperature estimated value eTEC in consideration of the exhaust flow rate, the heat capacity of the catalyst-carrying PM filter 73, the fuel addition amount FA, and the like.

<Effect of embodiment>
As described above in detail, according to the control apparatus for an internal combustion engine according to this embodiment, the following effects can be obtained.

  (1) In the control apparatus for an internal combustion engine of the present embodiment, the first exhaust temperature estimated value eTEA is calculated using the smoothed value SM set based on the fuel injection amount FI and the intake air amount GA. Thereby, since the estimation accuracy of the first exhaust temperature TEA is improved, the second exhaust temperature TEB can be accurately estimated.

  (2) In the diesel engine 1, when the fuel is added to the exhaust gas even though the converter catalyst bed temperature TC is lower than the lower limit temperature TClmt, the NOx catalytic converter 72 has a sufficient fuel oxidation reaction. There is a possibility that various problems (for example, the clogging of the converter occurs due to the fuel adhering to the NOx catalytic converter 72) due to the non-occurrence.

  In the control apparatus for an internal combustion engine of the present embodiment, the second exhaust temperature estimated value eTEB is calculated based on the first exhaust temperature estimated value eTEA, and the estimated converter catalyst bed temperature TCE is calculated based on the second exhaust temperature estimated value eTEB. Since the calculation is performed, the estimation accuracy of the converter catalyst bed temperature TC is improved. Thereby, since fuel addition by the fuel addition valve 71 is executed based on an appropriate determination result, the occurrence of the above problem can be suppressed.

  (3) In the diesel engine 1, when the fuel addition amount FA is greatly below the appropriate value during the execution of the PM regeneration control, the catalyst-carrying PM filter 73 may be clogged because PM is not sufficiently purified. is there. On the other hand, if the fuel addition amount FA is significantly higher than the appropriate value, the catalyst catalyst-type PM filter 73 may be damaged by the filter catalyst bed temperature TF becoming excessively high.

  In the control apparatus for an internal combustion engine of the present embodiment, the third exhaust temperature estimated value eTEC is calculated based on the first exhaust temperature estimated value eTEA, and the estimated filter catalyst bed temperature TFE is calculated based on the third exhaust temperature estimated value eTEC. Since the calculation is performed, the estimation accuracy of the filter catalyst bed temperature TF is improved. This makes it difficult for the fuel addition amount FA to be much lower or higher than the appropriate value, so that the above problem can be suppressed.

<Example of change>
In addition, the said embodiment can also be implemented as the following forms which changed this suitably, for example.

  In the above embodiment, the following configuration can also be adopted. That is, the estimated converter catalyst bed temperature TCE is calculated based on the third exhaust temperature estimated value eTEC, and the fuel addition amount FA can be set using the estimated converter catalyst bed temperature TCE in the S poison recovery control. .

  Incidentally, in the diesel engine 1, when the fuel addition amount FA is greatly lower than the appropriate value during the execution of the S poison recovery control, there is a possibility that the NOx occlusion ability is lowered because the SOx is not sufficiently reduced. . On the other hand, when the fuel addition amount FA greatly exceeds the appropriate value, the converter catalyst bed temperature TC and the filter catalyst bed temperature TF become excessively high, thereby causing damage to the NOx catalyst converter 72 and the catalyst-carrying PM filter 73. Sometimes.

  In this regard, when the above configuration is adopted, it is difficult to cause a state in which the fuel addition amount FA is significantly below or above the appropriate value, so that the above problem can be suppressed.

  In the above embodiment, the following configuration can also be adopted. That is, the estimated converter catalyst bed temperature TCE is calculated based on the second exhaust temperature estimated value eTEB, and whether or not the converter catalyst bed temperature TC is lower than the lower limit temperature TClmt based on the catalyst bed temperature TCE in the NOx reduction control. Can also be determined.

  Incidentally, in the diesel engine 1, when the fuel is added to the exhaust gas even though the converter catalyst bed temperature TC is lower than the lower limit temperature TClmt, the NOx catalytic converter 72 sufficiently generates an oxidation reaction of the fuel. There is a risk of various problems due to the absence.

  In this regard, when the above configuration is adopted, fuel addition by the fuel addition valve 71 is executed based on an appropriate determination result, so that the above problem can be suppressed.

  In the above embodiment, the present invention is embodied as a diesel engine control device, but the present invention is applied to an appropriate control device as long as it is an internal combustion engine control device that performs engine control using exhaust gas temperature as a parameter. be able to. Even in such a case, the operational effects according to the operational effects of the above-described embodiment can be achieved.

The block diagram which shows the whole structure of the diesel engine by which the control apparatus is mounted about embodiment which actualized the control apparatus of the internal combustion engine concerning this invention. 7 is a flowchart showing a processing procedure of “PM regeneration control processing” executed by the electronic control device in the embodiment. The flowchart which shows the process sequence of the "bed temperature control process" performed by the electronic controller in the same embodiment. 7 is a flowchart showing a processing procedure of “exhaust temperature estimation processing” executed by the electronic control unit in the embodiment. 7 is a flowchart showing a processing procedure of “exhaust temperature estimation processing” executed by the electronic control unit in the embodiment. The figure which shows the steady exhaust temperature calculation map used in the "exhaust temperature estimation process" of the embodiment. The figure which shows the annealing value calculation map used in the "exhaust temperature estimation process" of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 11 ... Engine main body, 12 ... Cylinder, 13 ... Combustion chamber.
21 ... Intake manifold, 22 ... Intake pipe, 23 ... Intake passage, 24 ... Air cleaner, 25 ... Intercooler, 26 ... Throttle valve.

31 ... Exhaust manifold, 32 ... Exhaust pipe, 33 ... Exhaust passage.
4 ... Turbocharger, 41 ... Compressor wheel, 42 ... Turbine wheel, 43 ... Rotor shaft.

DESCRIPTION OF SYMBOLS 5 ... Common rail type fuel supply apparatus, 51 ... Fuel injection valve, 52 ... Fuel tank, 53 ... Fuel pump, 54 ... Common rail.
6 ... Exhaust gas recirculation device, 61 ... Communication pipe, 62 ... EGR cooler, 63 ... EGR valve.

DESCRIPTION OF SYMBOLS 7 ... Exhaust gas purification apparatus, 71 ... Fuel addition valve, 72 ... NOx catalytic converter, 73 ... Catalyst carrying type PM filter
DESCRIPTION OF SYMBOLS 9 ... Electronic controller, 91 ... Rotational speed sensor, 92 ... Cooling water temperature sensor, 93 ... Air flow meter, 94 ... Intake temperature sensor, 95 ... Atmospheric pressure sensor.

Claims (17)

Engine control means for performing engine control using the exhaust temperature as a parameter;
An input temperature estimating means for calculating an estimated value of the input exhaust temperature using an exhaust temperature at the engine body or an exhaust temperature corresponding to the temperature as an input exhaust temperature;
In an internal combustion engine control device comprising output temperature estimating means for calculating an estimated value of the output exhaust temperature based on the estimated value of the input exhaust temperature, using the exhaust gas temperature used for the engine control as an output exhaust gas temperature,
An internal combustion engine control apparatus comprising: an estimation means for calculating an estimated value of the input exhaust gas temperature using an annealing value set with at least one of a fuel injection amount and an intake air amount as a parameter. The control apparatus for an internal combustion engine according to claim 1,
The estimation means calculates the estimated value of the input exhaust temperature from the following calculation formula:

Y <-Y (n-1) + {Z (n) -Y (n-1)} / X

(A) The “Y” is an estimated value of the input exhaust temperature in the current control cycle. (B) The “Y (n−1)” is an estimated value of the input exhaust temperature calculated in the previous control cycle. (C) “Z (n)” is a reference value of the estimated value of the input exhaust temperature calculated based on the engine operating state of the current control cycle. (D) The “X” is a parameter with at least one of the fuel injection amount and the intake air amount as a parameter. Set annealing value

A control device for an internal combustion engine. The control apparatus for an internal combustion engine according to claim 2,
The estimation means calculates the “X” from an arithmetic model in which a relationship between at least one of the fuel injection amount and intake air amount and the smoothed value is set in advance. apparatus. The control device for an internal combustion engine according to claim 2 or 3,
The control device for an internal combustion engine, wherein the estimation means calculates the “Z (n)” from a calculation model in which a relationship between an engine operating state and the input exhaust gas temperature is set in advance. In the control device for an internal combustion engine according to any one of claims 1 to 4,
The control device for an internal combustion engine, wherein the estimation means increases the smoothing value as the fuel injection amount increases. In the control device for an internal combustion engine according to any one of claims 1 to 5,
The control device for an internal combustion engine, wherein the estimation means decreases the smoothing value as the intake air amount increases. In the control device for an internal combustion engine according to any one of claims 1 to 6,
The output temperature estimation means calculates the estimated value of the output exhaust gas temperature by applying the estimated value of the input exhaust gas temperature to a heat exchange model that simulates heat exchange between the exhaust gas and the exhaust system. A control device for an internal combustion engine. In the control device for an internal combustion engine according to any one of claims 1 to 7,
The internal combustion engine includes an additive supply means for supplying an additive into the exhaust, and a catalyst device for storing nitrogen oxides in the exhaust.
The control device performs a process of reducing the nitrogen oxide through supply of the additive by the additive supply means when a condition for reducing the nitrogen oxide stored in the catalyst device is satisfied. In addition, the estimated value of the output exhaust temperature is included in at least the condition that the estimated value of the temperature of the catalyst device is equal to or higher than the reduction temperature at which the reduction reaction of nitrogen oxides by the additive can occur. An estimated value of the temperature of the catalyst device is calculated on the basis of the control device for the internal combustion engine. In the control device for an internal combustion engine according to any one of claims 1 to 8,
The internal combustion engine includes an additive supply means for supplying an additive into the exhaust, and a catalyst device for storing nitrogen oxides in the exhaust.
The control device performs a process of reducing the sulfur oxide through supply of the additive by the additive supply means when a condition for reducing the sulfur oxide stored in the catalyst device is satisfied. And the supply amount of the additive is set based on the estimated value of the temperature of the catalytic device and the target value of the temperature of the catalytic device, and further based on the estimated value of the output exhaust gas temperature. A control apparatus for an internal combustion engine, which calculates an estimated value of temperature. The control device for an internal combustion engine according to any one of claims 1 to 9,
The internal combustion engine includes an additive supply means for supplying an additive into the exhaust, a catalyst device that promotes an oxidation reaction of the additive, and an exhaust filter that is disposed downstream of the catalyst device and captures particulate matter With
The control device performs a process of purifying the particulate matter through supply of the additive by the additive supply means when a condition for purifying the particulate matter captured by the exhaust filter is satisfied. And the supply amount of the additive based on the estimated value of the temperature of the exhaust filter and the target value of the temperature of the exhaust filter, and further, based on the estimated value of the output exhaust temperature, A control apparatus for an internal combustion engine, which calculates an estimated value of temperature. In a control device for an internal combustion engine that performs engine control using an estimated value of exhaust temperature,
An internal combustion engine control apparatus comprising: an estimation unit that calculates an estimated value of the exhaust gas temperature using an annealing value set based on at least one of a fuel injection amount and an intake air amount. Based on the estimated value after calculating the estimated value of the input exhaust gas temperature using the exhaust gas temperature at the engine body or the exhaust gas temperature corresponding to the exhaust temperature as the input exhaust gas temperature and the exhaust gas temperature used for engine control as the output exhaust gas temperature. In the exhaust gas temperature estimation method of the internal combustion engine for calculating the estimated value of the output exhaust gas temperature,
An exhaust temperature estimation method for an internal combustion engine, characterized in that an annealing value in which at least one of a fuel injection amount and an intake air amount is set as a parameter is used in calculating the estimated value of the input exhaust temperature. The exhaust gas temperature estimating method for an internal combustion engine according to claim 12,
The estimated value of the input exhaust temperature is calculated from the following formula:

Y <-Y (n-1) + {Z (n) -Y (n-1)} / X

(A) The “Y” is an estimated value of the input exhaust temperature in the current estimation cycle. (B) The “Y (n−1)” is an estimated value of the input exhaust temperature calculated in the previous estimation cycle. (C) “Z (n)” is a reference value of the estimated value of the input exhaust gas temperature calculated based on the engine operating state of the current estimation cycle. (D) “X” is a parameter with at least one of the fuel injection amount and the intake air amount. Set annealing value

An exhaust gas temperature estimation method for an internal combustion engine. The exhaust gas temperature estimation method for an internal combustion engine according to claim 13,
An exhaust gas temperature estimation method for an internal combustion engine, wherein a calculation model in which a relationship between at least one of the fuel injection amount and the intake air amount and the smoothed value is set in advance is used for calculating the “X”. The exhaust gas temperature estimation method for an internal combustion engine according to claim 13 or 14,
An exhaust gas temperature estimation method for an internal combustion engine, wherein a calculation model in which a relationship between an engine operating state and the input exhaust gas temperature is set in advance is used for calculating the “Z (n)”. The exhaust gas temperature estimation method for an internal combustion engine according to any one of claims 12 to 15,
An exhaust temperature estimation method for an internal combustion engine, wherein the smoothing value is increased as the fuel injection amount increases. The exhaust gas temperature estimation method for an internal combustion engine according to any one of claims 12 to 16,
An exhaust temperature estimation method for an internal combustion engine, wherein the smoothing value is decreased as the intake air amount increases.

Images