JP5163553B2 - Diesel engine control device - Google Patents

Description

  The present invention controls the opening of the intake throttle valve to control the temperature of the exhaust purification catalyst during deceleration operation of the diesel engine, and forcibly opens and closes the EGR valve during deceleration operation of the diesel engine. The present invention relates to a control device for a diesel engine for diagnosing the presence or absence of an abnormality of an EGR device based on the degree of change in intake pipe pressure and the like.

  Conventionally, as a control device of this type of diesel engine, for example, there is one described in Patent Document 1. A conventional diesel engine of a control device including the one described in Patent Document 1 is provided with an EGR device for introducing exhaust gas from an exhaust passage to an intake passage. The intake passage is provided with an intake throttle valve that makes the flow area of intake air variable. The flow rate of the exhaust gas introduced into the intake passage is adjusted by controlling the opening degree of the EGR valve and the opening degree control of the intake throttle valve provided in the EGR passage by the control device.

  By the way, in such a diesel engine, the malfunction of the EGR valve occurs or the EGR passage is clogged, so that the flow rate of the exhaust gas introduced into the intake passage cannot be suitably controlled. May occur.

  Therefore, the EGR valve is forcibly opened and closed during the deceleration operation of the diesel engine which does not need to execute the EGR valve operation control for the combustion control of the diesel engine 10, and the change in the intake pipe pressure PIM accompanying the opening and closing thereof. An amount ΔPIM is obtained, and the presence / absence of an abnormality in the EGR device is diagnosed based on the change amount ΔPIM. That is, paying attention to the fact that the amount of change ΔPIM of the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve becomes smaller as the degree of clogging of the EGR passage becomes larger, the EGR device is informed that the amount of change ΔPIM falls below the predetermined amount C1. It is determined that an abnormality has occurred.

  On the other hand, during the deceleration operation of the diesel engine, the opening degree of the intake throttle valve is controlled so as to suppress a decrease in the catalyst temperature.

JP 2002-227727 A

  By the way, in the conventional diesel engine control device, an abnormality of the EGR device occurs while the intake throttle valve is controlled to an opening degree for suppressing a decrease in the catalyst temperature during the deceleration operation of the diesel engine. Diagnosis is performed. Here, the EGR valve malfunctions, such as when the EGR valve is stuck almost fully closed, or the EGR passage is clogged, and the exhaust flow area in the EGR passage is considerably small. If the degree of is large, the amount of change ΔPIM of the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve is sufficiently small as compared to the normal time, so that abnormality diagnosis can be performed with a certain degree of accuracy.

  However, for example, when the malfunction of the EGR valve occurs and the operation range is limited from the fully closed position to an intermediate opening between the fully closed position and the fully opened position, or the EGR valve is normal but the EGR passage is clogged. Therefore, when the degree of abnormality of the EGR device is relatively small, such as when the exhaust circulation area in the EGR passage is about half, the abnormality diagnosis can be performed accurately for the following reason. Can not. That is, in this case, the degree of divergence of the change amount ΔPIM of the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve between when the abnormality has occurred and when it is normal is small. Moreover, since the intake pipe pressure PIM constantly varies, the amount of change ΔPIM also constantly varies. Therefore, it becomes difficult for a significant difference to occur in the amount of change ΔPIM in the intake pipe pressure PIM between when the abnormality occurs in the EGR device and when it is normal. As a result, it is diagnosed that the EGR device is normal even though the EGR device is abnormal, or is diagnosed as abnormal even though the EGR device is normal. I can't do it well.

  This problem is not limited to diagnosing the presence / absence of an abnormality in the EGR device based on the amount of change in the intake pipe pressure accompanying opening / closing of the EGR valve, but the amount of change in intake air amount accompanying opening / closing of the EGR valve. This can also occur generally in common in the case where a division value obtained by dividing the engine rotation speed is obtained and the presence or absence of an abnormality in the EGR device is diagnosed based on the amount of change in the division value. In addition to diagnosing the presence or absence of an abnormality in the EGR device based on the amount of change in the intake pipe pressure accompanying the opening and closing of the EGR valve and the amount of change in the above-mentioned division value, in short, the change in the intake pipe pressure accompanying the opening and closing of the EGR valve If it is possible to diagnose the presence or absence of an abnormality of the EGR device based on the degree or the change degree of the division value, it can occur in general.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a control device for a diesel engine that can accurately perform abnormality diagnosis even when the degree of abnormality of the EGR device is small. It is in.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
(1) The invention according to claim 1 is an intake throttle valve that is provided in the intake passage to change the flow area of the intake air, an exhaust purification catalyst that is provided in the exhaust passage and purifies exhaust, and intake air from the exhaust passage. The present invention is applied to a diesel engine including an EGR passage for introducing exhaust gas into the passage and an EGR device that is provided in the passage and has an EGR valve that changes the flow area of the exhaust gas. An intake throttle valve control means for controlling the opening degree of the intake throttle valve to control the temperature of the purification catalyst; and the EGR valve is forcibly opened and closed during deceleration operation of the diesel engine, and the intake pipe pressure associated with the opening and closing is controlled. A control unit for diagnosing whether there is an abnormality in the EGR device based on the degree of change; And with forced changing means for forcibly changing the closing side of the opening than the opening degree controlled by the intake throttle valve control means, the forced change section the intake throttle based on the state of the exhaust gas purifying catalyst The gist is to set a change mode of the opening degree of the valve .

  According to this configuration, when diagnosing the presence or absence of abnormality in the EGR device, the intake throttle valve has an opening closer to the closing side than the opening controlled by the intake throttle valve control means to control the temperature of the exhaust purification catalyst. Is done. Here, the closer the opening of the intake throttle valve is to the close side, the greater the degree of change in the intake pipe pressure that accompanies the opening and closing of the EGR valve. For this reason, in comparison with the case where the diagnosis of the EGR device is performed with the intake throttle valve being controlled by the intake throttle valve control means, the intake air in the case where the abnormality occurs in the EGR device and in the normal case The deviation degree of the change degree of the tube pressure can be increased. Therefore, even when the degree of abnormality of the EGR device is small, abnormality diagnosis can be performed with high accuracy.

Here, if the opening degree of the intake throttle valve is forcibly changed, the state of the exhaust purification catalyst, such as the temperature of the exhaust purification catalyst, the degree of deterioration, the amount of particulate matter accumulated in the exhaust, etc. will be affected accordingly. Will be affected. In this respect, according to the above-described configuration, it is possible to accurately set the change mode of the opening degree of the intake throttle valve by taking into account the state of the exhaust purification catalyst.

(2) The invention of claim 1, such as by the invention of claim 2, wherein the force changing means sets the degree of opening of the modification of the intake throttle valve based on the temperature of the exhaust gas purifying catalyst It can be embodied in such a manner.

(3) an invention according to claim 3, in the control device for a diesel engine according to claim 2, wherein the force changing means, prior Symbol exhaust gas purifying catalyst wherein the intake throttle valve than when higher when the temperature is low The gist of this is to set the opening degree to the closed side.

  Normally, when the opening of the intake throttle valve is closed from the opening controlled by the control means, the amount of air flowing into the exhaust purification catalyst decreases, so that the temperature of the exhaust purification catalyst is unlikely to decrease. According to the above configuration, when the temperature of the exhaust purification catalyst is relatively low, the opening degree of the intake throttle valve is set to a relatively closed side, so that it is preferable to reduce the temperature of the exhaust purification catalyst during the deceleration operation of the diesel engine. The degree of change in the intake pipe pressure accompanying opening / closing of the EGR valve can be further increased. Therefore, the accuracy of abnormality diagnosis of the EGR device can be further improved.

On the other hand, if the opening of the intake throttle valve is excessively closed when the temperature of the exhaust purification catalyst is relatively high, the temperature of the exhaust purification catalyst may increase excessively and deterioration of the exhaust purification catalyst may progress.
In this respect, according to the above configuration, when the temperature of the exhaust purification catalyst is relatively high, the opening degree of the intake throttle valve is set to a relatively open side, so that the opening degree of the intake throttle valve is forcibly closed. Due to the change, it is possible to suppress the temperature of the exhaust purification catalyst from rising excessively, and consequently the progress of the deterioration of the exhaust purification catalyst.

(4) According to a fourth aspect of the invention, in the control device for a diesel engine according to claim 2 or claim 3, wherein the force changing means, when the temperature of the pre-Symbol exhaust purification catalyst is higher than a predetermined temperature The gist is to prohibit the forced change of the opening of the intake throttle valve.

  If the opening degree of the intake throttle valve is excessively closed when the temperature of the exhaust purification catalyst is high to some extent, the temperature of the exhaust purification catalyst may excessively increase and deterioration of the exhaust purification catalyst may progress.

  In this regard, according to the above configuration, when the temperature of the exhaust purification catalyst is higher than the predetermined temperature, forcibly changing the opening of the intake throttle valve is prohibited. Therefore, it is possible to avoid that the temperature of the exhaust purification catalyst rises excessively due to the change to the closed side, and that the deterioration of the exhaust purification catalyst proceeds.

(5) an invention according to any one of claims 1 to 4, such as by the invention of claim 5, heating agent supply means for supplying a heating agent to the exhaust gas purifying catalyst And the forcible change means can be embodied with a mode in which a change mode of the opening degree of the intake throttle valve is set based on a control state of the temperature raising agent supply means.

( 6 ) The invention according to claim 6 is the diesel engine control device according to claim 5 , wherein the forcible change means is configured to raise the temperature of the exhaust purification catalyst by the temperature raising agent supply means. The gist of the present invention is to set the opening of the intake throttle valve to the closed side as compared to when not.

  In the configuration in which the opening degree of the intake throttle valve is closer to the opening degree controlled by the control means, the amount of air flowing into the exhaust purification catalyst due to the forced change of the opening degree of the intake throttle valve is reduced. Therefore, if the opening degree of the intake throttle valve is forcibly changed while the temperature of the exhaust purification catalyst is raised through the control of the temperature raising agent supply means, the temperature increase of the exhaust purification catalyst is promoted. . According to the above configuration, when the temperature of the exhaust purification catalyst is raised through the control of the temperature raising agent supply means, the degree of change in the intake pipe pressure accompanying the opening / closing of the EGR valve is preferably promoted while favorably promoting the temperature rise of the exhaust purification catalyst. Can be made even larger. Therefore, the accuracy of abnormality diagnosis of the EGR device can be further improved.

  On the other hand, in the configuration in which the opening degree of the intake throttle valve is opened more than the opening degree controlled by the control means, the air flowing into the exhaust purification catalyst due to the forced change of the opening degree of the intake throttle valve is reduced. Therefore, if the opening of the intake throttle valve is forcibly changed while the exhaust purification catalyst is being heated through the control of the temperature raising agent supply means, the temperature increase of the exhaust purification catalyst will proceed appropriately. There is a risk of disappearing.

  In this regard, according to the above configuration, when the temperature of the exhaust purification catalyst is raised through the control of the temperature raising agent supply means, the opening degree of the intake throttle valve is set to the closed side compared to when it is not, It is possible to suppress the temperature increase of the exhaust purification catalyst from not proceeding favorably due to forcibly changing the opening of the intake throttle valve to the open side.

(7) The invention according to any one of claims 1 to 6, such as by the invention of claim 7, deposited for estimating the amount of particulate matter deposited on the exhaust purifying catalyst An amount estimating means is provided, and the forcible changing means can be embodied in such a manner that the opening degree of the intake throttle valve is set based on the accumulation amount of the particulate matter estimated by the accumulation amount estimating means.

(8) an invention according to claim 8, in the control device for a diesel engine according to claim 7, wherein the force changing means, the deposition amount of the particulate matter Tokoro estimated by pre Symbol accumulation amount estimating means The gist is to prohibit the forced change of the opening degree of the intake throttle valve when the amount exceeds the fixed amount and the temperature of the exhaust purification catalyst exceeds a predetermined temperature.

  Usually, in a state where the amount of particulate matter deposited on the exhaust purification catalyst is large to some extent and the temperature of the exhaust purification catalyst is high to some extent, the temperature of the exhaust purification catalyst is prevented from excessively rising. Therefore, the opening degree of the intake throttle valve is controlled so as to cool the exhaust purification catalyst by adjusting the air flowing into the exhaust purification catalyst. At this time, if the amount of air flowing into the exhaust purification catalyst decreases excessively by forcibly changing the opening of the intake throttle valve to the closed side, the temperature of the exhaust purification catalyst will excessively rise, and the exhaust purification catalyst There is a possibility that deterioration of the catalyst proceeds.

  In this regard, according to the above configuration, when the estimated amount of accumulated particulate matter exceeds a predetermined amount and the temperature of the exhaust purification catalyst exceeds the predetermined temperature, forcibly changing the opening of the intake throttle valve is prohibited. Is done. As a result, it is possible to avoid an excessive increase in the temperature of the exhaust purification catalyst due to forcibly changing the opening of the intake throttle valve to the closed side, and thus the progress of the deterioration of the exhaust purification catalyst. become able to.

( 9 ) The invention according to claim 9 is the control apparatus for a diesel engine according to any one of claims 1 to 8 , wherein the forcible change means is based on a state of an external environment of the diesel engine. The gist is to set a change mode of the opening of the intake throttle valve.

  The closer the opening of the intake throttle valve is to the close side, the greater the degree of change in the intake pipe pressure that accompanies the opening and closing of the EGR valve. Further, as the opening of the intake throttle valve is opened, the degree of change in the intake air amount per unit engine rotational speed with the opening and closing of the EGR valve becomes larger. However, the relationship between the opening degree of the intake throttle valve and the change degree of the intake pipe pressure, and the relationship between the opening degree of the intake throttle valve and the change degree of the intake air amount per unit engine rotational speed are, for example, the outside air temperature and It depends on the external environment of the diesel engine, such as atmospheric pressure. Therefore, according to the above configuration, the target opening of the intake throttle valve can be accurately set when the opening of the intake throttle valve is forcibly changed.

( 10 ) According to a ninth aspect of the present invention, as in the tenth aspect of the present invention, in the control device for a diesel engine, the forcible change means changes the opening degree of the intake throttle valve based on the outside air temperature. It can be embodied with a mode such as setting.

(11) The invention according to claim 11, in the control device for a diesel engine according to any one of claims 1 to 10, wherein the force changing means of the intake throttle valve based on the engine rotational speed The gist is to set the change mode of the opening.

  The closer the opening of the intake throttle valve is to the close side, the greater the degree of change in the intake pipe pressure that accompanies the opening and closing of the EGR valve. Further, as the opening of the intake throttle valve is opened, the degree of change in the intake air amount per unit engine rotational speed with the opening and closing of the EGR valve becomes larger. However, the relationship between the opening of the intake throttle valve and the degree of change in the intake pipe pressure, and the relationship between the opening of the intake throttle valve and the degree of change in the intake air amount per unit engine speed depend on the engine speed. It will be different. Therefore, according to the above configuration, the target opening of the intake throttle valve can be accurately set when the opening of the intake throttle valve is forcibly changed.

( 12 ) The invention according to claim 12 is the control apparatus for a diesel engine according to any one of claims 1 to 11 , wherein the forcible changing means is forcing the opening of the intake throttle valve. When the magnitude of at least one of the abnormal noise and the impact generated by the change is estimated in advance, and the magnitude of at least one of the estimated abnormal noise and the impact exceeds the upper limit value of the allowable range, the intake air The gist is to prohibit the forced change of the opening of the throttle valve.

If the opening degree of the intake throttle valve is forcibly changed, there is a possibility that an abnormal noise or an impact caused by this change becomes a problem.
In this regard, according to the above-described configuration, the magnitude of at least one of the abnormal noise and the impact that occurs due to the forced change of the opening of the intake throttle valve is estimated in advance, and at least the estimated abnormal noise and the impact are at least If one of the sizes exceeds the upper limit of the allowable range, forcibly changing the opening of the intake throttle valve is prohibited. As a result, it is possible to avoid abnormal noise and impact that are caused by the forced change of the opening of the intake throttle valve.

( 13 ) The invention according to claim 13 is the diesel engine control device according to claim 12 , wherein the forcible change means sets the upper limit value of the allowable range based on the engine operating state. It is said.

  Even if the noise and impact generated by forcibly changing the opening of the intake throttle valve are the same, the more the noise and impact generated by other factors are, the larger the intake throttle valve becomes. The influence of the abnormal noise and impact generated by forcibly changing the opening degree of the motor on the overall abnormal noise and impact is reduced. According to the above configuration, since the upper limit value of the allowable range is set based on the engine operating state, abnormal noise and impact that occur when the opening of the intake throttle valve is forcibly changed are totally different. The upper limit value can be accurately set according to the magnitude of the influence on the sound and impact.

( 14 ) The invention according to claim 14 is the control apparatus for a diesel engine according to claim 12 or claim 13 , wherein the diesel engine is mounted on a vehicle, and the forcible changing means is in a running state of the vehicle. The gist is to set the upper limit value of the allowable range based on the above.

  Even if the noise and impact generated by forcibly changing the opening of the intake throttle valve are the same, the more the noise and impact generated by other factors are, the larger the intake throttle valve becomes. The influence of the abnormal noise and impact generated by forcibly changing the opening degree of the motor on the overall abnormal noise and impact is reduced. According to the above configuration, since the upper limit value of the allowable range is set based on the running state of the vehicle, the abnormal noise and impact that occur when the opening degree of the intake throttle valve is forcibly changed are totally reduced. The upper limit value can be accurately set according to the magnitude of the influence on the abnormal noise and impact.

( 15 ) The invention according to claim 15 is the diesel engine control device according to any one of claims 1 to 14 , wherein the forcible change means forcibly opens the opening of the intake throttle valve. The gist of the change is to gradually change the opening of the intake throttle valve.

If this is abruptly performed when the opening of the intake throttle valve is forcibly changed, there may be a problem with abnormal noise or impact generated.
In this regard, according to the above configuration, when the opening degree of the intake throttle valve is forcibly changed, the opening degree of the intake throttle valve is gradually changed, so that the opening degree of the intake throttle valve is forcibly changed. As a result, it is possible to reduce the magnitude of abnormal noise and impact generated.

The schematic block diagram which shows schematic structure of the diesel engine and the electronic controller which controls this about 1st Embodiment of the control apparatus of the diesel engine which concerns on this invention. The flowchart which shows the process sequence of the basic opening degree control of the intake throttle valve in the embodiment. (A) A graph showing the relationship between the opening of the intake throttle valve and the intake pipe pressure, (b) A relationship between the opening of the intake throttle valve and the amount of change in the intake pipe pressure accompanying opening and closing of the EGR valve. Graph. The flowchart which shows the process sequence of abnormality diagnosis control of the EGR apparatus in the embodiment. The flowchart which shows the process sequence of the forced opening change of the intake throttle valve in the embodiment. The map which prescribed | regulated the relationship between the catalyst temperature and the opening degree change amount of an intake throttle valve in the embodiment. (A) A graph showing the relationship between the opening of the intake throttle valve and the amount of intake air per unit engine speed, (b) per unit engine speed per opening of the intake throttle valve and opening / closing of the EGR valve The graph which showed the relationship with the variation | change_quantity of intake air amount. The flowchart which shows the process sequence of abnormality diagnosis control of the EGR apparatus in 2nd Embodiment. The flowchart which shows the process sequence of the forced opening change of the intake throttle valve in the embodiment. The map which prescribed | regulated the relationship between the catalyst temperature and the opening degree change amount of an intake throttle valve in the embodiment.

<First Embodiment>
Hereinafter, with reference to FIGS. 1-6, 1st Embodiment which actualized the control apparatus of the diesel engine which concerns on this invention as a control apparatus of the vehicle-mounted diesel engine 10 is described.

In FIG. 1, schematic structure of the diesel engine 10 which concerns on this embodiment, and the electronic controller 50 which controls this is shown.
As shown in the figure, the diesel engine 10 includes an engine body 11, an intake passage 21, and an exhaust passage 31. The intake passage 21 is provided with an intake throttle valve 22 for metering intake air by changing the flow area of intake air in the passage 21. The intake throttle valve 22 is driven by a motor (not shown). In the operation control of the intake throttle valve 22, the operation of the motor is controlled according to the engine operating state and the opening degree TA of the intake throttle valve 22 is controlled, so that the intake throttle valve 22 is introduced into the combustion chamber 12 of the engine body 11. The flow rate of intake air (hereinafter referred to as “intake air amount”) GA is adjusted. The engine body 11 is provided with a fuel injection valve 13 for directly injecting fuel into the combustion chamber 12. Then, the air that is metered by the intake throttle valve 22 and supplied to the combustion chamber 12 and the fuel injected from the fuel injection valve 13 are mixed, and the mixture thus mixed is used for combustion in the combustion chamber 12. Is done. Then, the engine output shaft (not shown) is rotationally driven by the expansion energy due to the combustion, whereby the driving wheels of the vehicle are rotationally driven. Further, the exhaust gas generated by the combustion in the combustion chamber 12 is discharged to the exhaust passage 31 and purified when passing through the exhaust purification catalyst 32 provided in the passage 31. Here, the exhaust purification catalyst 32 includes a filter 32a that collects particulate matter (hereinafter referred to as “PM”) in the exhaust. The filter 32a collects PM in the exhaust gas by passing the exhaust gas through a porous partition made of ceramics or the like. The filter 32a carries an NOx storage reduction catalyst. When the NOx catalyst is activated, the trapped PM is combusted (oxidized) through a reaction triggered by the NOx catalyst. It is supposed to be removed.

  The diesel engine 10 is provided with an EGR device 40 for introducing a part of the exhaust gas into the intake passage 21. The EGR device 40 is provided in the middle of the EGR passage 41 and the EGR passage 41 that connect a portion of the intake passage 21 downstream of the intake throttle valve 22 and a portion of the exhaust passage 31 upstream of the exhaust purification catalyst 32. And an EGR valve 42 that can change the flow area of the exhaust gas. The EGR valve 42 is driven by a step motor (not shown). In the operation control of the EGR valve 42 (hereinafter referred to as “EGR control”), the operation of the step motor is controlled in accordance with the engine operating state to control the opening of the EGR valve 42 (hereinafter referred to as “EGR opening”). Thus, the flow rate of exhaust gas (hereinafter, “EGR amount”) introduced into the intake passage 21 through the EGR passage 41 is adjusted.

  The electronic control unit 50 that controls the diesel engine 10 includes a microcomputer. The electronic control device 50 receives detection signals from various sensors for detecting the engine operating state and the vehicle traveling state.

  As various sensors, for example, an engine rotation speed sensor 61 for detecting an engine rotation speed NE that is the rotation speed of the engine output shaft, and an accelerator opening ACCP that is a depression amount of an accelerator pedal (not shown). An opening degree sensor 62 and an intake air amount sensor 63 for detecting the intake air amount GA are provided. Further, an intake throttle valve opening sensor 64 for detecting the opening degree TA of the intake throttle valve 22 and a pressure (hereinafter referred to as “intake pipe pressure”) PIM on the downstream side of the intake throttle valve 22 in the intake passage 21 are detected. Intake pipe pressure sensor 65 is provided. Further, a catalyst temperature sensor 66 for detecting a catalyst temperature TC that is the temperature of the exhaust purification catalyst 32 is provided. A vehicle speed sensor 67 for detecting the vehicle speed V and a shift position sensor 68 for detecting a shift position SHIFT of an automatic transmission (not shown) are provided.

  The electronic control unit 50 performs various calculations based on detection signals from various sensors, and performs engine control such as operation control of the intake throttle valve 22, operation control of the fuel injection valve 13, and EGR control based on the calculation results. Run.

  Further, the electronic control unit 50 estimates the accumulation amount D of the particulate matter accumulated on the filter 32a of the exhaust purification catalyst 32 based on the engine operating state such as the engine rotation speed NE and the fuel injection amount Q. .

  Next, the basic opening degree control of the intake throttle valve 22 will be described with reference to FIG. FIG. 2 is a flowchart showing a processing procedure for basic opening degree control of the intake throttle valve 22. A series of processing shown in this flowchart is repeatedly executed by the electronic control unit 50 during operation of the diesel engine 10.

  In this process, first, it is determined whether or not the diesel engine 10 is decelerating (step S101). Here, when the diesel engine 10 is not decelerating (step S101: “NO”), next, the target value of the EGR amount is based on the engine operating state such as the engine rotational speed NE and the fuel injection amount Q. A target EGR amount EGtrg is derived (step S102). Next, a target opening degree TAE, which is a target value of the opening degree of the intake throttle valve 22, is set based on the target EGR amount EGtrg and the EGR opening degree set through the EGR control (step S103). Here, in the EGR control of the present embodiment, the intake pipe pressure PIM decreases with respect to the exhaust pipe pressure and the EGR amount increases as the opening of the intake throttle valve 22 is closed. The EGR amount is controlled by controlling both the opening and the opening of the intake throttle valve 22.

  On the other hand, when the diesel engine 10 is decelerating in step S101 (step S101: “YES”), next, a target catalyst temperature TCtrg which is a target value of the catalyst temperature TC is derived (step S104). Next, the catalyst temperature TC is read (step S105), and the target opening TAC of the intake throttle valve 22 is set based on the target catalyst temperature TCtrg and the catalyst temperature TC (step S106). That is, during the deceleration operation of the diesel engine 10, a fuel cut that stops fuel injection through the fuel injection valve 13 is performed, and the catalyst temperature TC tends to decrease accordingly. Therefore, for example, when the catalyst temperature TC is lower than the target catalyst temperature TCtrg, the target opening TAC of the intake throttle valve 22 is set closer to the close side as the degree of deviation between the catalyst temperature TC and the target catalyst temperature TCtrg is larger. The amount of air flowing into the exhaust purification catalyst 32 is reduced to suppress a decrease in the catalyst temperature TC.

  When the target openings TAE, TAC of the intake throttle valve 22 are set in the above-described steps S103 and S106, the intake throttle valve 22 is then driven to achieve the target openings TAE, TAC, and this series of processing is performed. Is temporarily terminated. The processing from step S104 to step S107 is referred to as “deceleration basic opening degree control”.

  By the way, in such a diesel engine 10, the flow rate of the exhaust gas introduced into the intake passage 21 can be suitably controlled by clogging in the EGR passage 41 or malfunction of the EGR valve 42. Problems such as being unable to do so may occur.

  Therefore, in the present embodiment, the EGR valve 42 is forcibly opened and closed during the deceleration operation of the diesel engine 10 that does not need to execute the EGR control for the combustion control of the diesel engine 10, and the intake pipe accompanying the opening and closing thereof A change amount ΔPIM of the pressure PIM is obtained, and the presence or absence of abnormality of the EGR device 40 is diagnosed based on the change amount ΔPIM. Specifically, the intake pipe pressure PIMcls when the operation command for fully closing the EGR valve 42 is output, and the intake pipe pressure PIMopn when the operation command for fully opening the EGR valve 42 is output. The absolute value ΔPIM (= | PIMcls−PIMpn |) of the deviation is calculated, and when the absolute value ΔPIM of the deviation falls below the predetermined value A1, it is determined that an abnormality has occurred in the EGR device 40. This is because the amount of change ΔPIM in the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve 42 decreases as the degree of clogging of the EGR passage 41 increases.

  Incidentally, as described above, in the conventional diesel engine control device, the intake throttle valve 22 remains at the opening degree TAC set through the basic opening degree control during deceleration during the deceleration operation of the diesel engine 10. An abnormality diagnosis of the EGR device 40 is performed. However, even if the degree of abnormality of the EGR device 40 is large, such as when the EGR valve 42 is fixed almost completely closed or the EGR passage 41 is clogged and the exhaust flow area is almost lost. For example, the amount of change ΔPIM in the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve 42 is sufficiently small compared to the normal time, so that abnormality diagnosis can be performed with a certain degree of accuracy.

  However, for example, when the operation failure of the EGR valve 42 occurs and the operation range is limited to an opening between the fully closed state and the fully closed and fully opened state, or the EGR passage 42 is normal but the EGR passage When the degree of abnormality of the EGR device 40 is relatively small as in the case where the exhaust flow area is halved due to clogging of 41, abnormality diagnosis cannot be performed with high accuracy for the following reason. That is, in this case, the degree of divergence of the change amount ΔPIM of the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve 42 between when the abnormality has occurred and when it is normal is small. Moreover, since the intake pipe pressure PIM constantly varies, the amount of change ΔPIM also constantly varies. Therefore, it becomes difficult for a significant difference to occur in the change amount ΔPIM of the intake pipe pressure PIM between when the abnormality occurs in the EGR device 40 and when it is normal. As a result, it is diagnosed that the EGR device 40 is normal even though the EGR device 40 is abnormal, or is diagnosed as abnormal even though the EGR device 40 is normal. Diagnosis cannot be made with high accuracy.

  Therefore, in the present embodiment, when the abnormality of the EGR device 40 is diagnosed through the electronic control device 50, the intake throttle valve can be used so that the abnormality diagnosis can be accurately performed even when the degree of abnormality of the EGR device 40 is small. 22 is forcibly changed to the opening degree TAD on the closing side with respect to the opening degree TAC controlled by the basic opening degree control at the time of deceleration.

  Here, the principle of the present invention will be described with reference to FIG. 3A is a graph showing the relationship between the opening degree TA of the intake throttle valve 22 and the intake pipe pressure PIM, and FIG. 3B is a graph showing the opening degree TA of the intake throttle valve 22 and EGR. 6 is a graph showing a relationship with a change amount ΔPIM of intake pipe pressure PIM that accompanies opening and closing of a valve 42. All of these assume the case where the EGR device 40 is normal.

  First, as shown in FIG. 3A, the intake pipe pressure PIMopn when the EGR valve 42 is fully opened is higher than the intake pipe pressure PIMcls when the EGR valve 42 is fully closed. This is because air in the exhaust passage 31 is introduced into the intake passage 21 through the opened EGR valve 42 when the EGR valve 42 is fully opened. Here, the intake pipe pressures PIMopn and PIMcls both decrease as the opening of the intake throttle valve 22 is closed, but the intake pipe pressures PIMopn and PIMcls decrease with respect to the change in the opening of the intake throttle valve 22 at this time. The amount is greater when the EGR valve 42 is fully closed than when the EGR valve 42 is fully open. This is because when the EGR valve 42 is fully closed, the air in the exhaust passage 31 is not introduced into the intake passage 21, and the intake pipe pressure PIM is increased by the amount that the opening of the intake throttle valve 22 is closed. It is because it falls. Therefore, as shown in FIG. 3B, the amount of change ΔPIM in the intake pipe pressure PIM that accompanies the opening and closing of the EGR valve 42 increases as the opening of the intake throttle valve 22 is closed. Therefore, when the abnormality of the EGR device 40 is diagnosed, the intake throttle valve 22 is forcibly changed to the opening degree TAD closer to the opening degree TAC than the opening degree TAC controlled by the basic opening degree control at the time of deceleration. Compared with the case where the diagnosis of the EGR device 40 is performed with the valve 22 kept at the opening degree TAC, the difference in the change ΔPIM in the intake pipe pressure PIM between when the EGR device 40 is abnormal and when it is normal The degree can be increased.

  Next, the abnormality diagnosis control of the EGR device 40 will be described with reference to FIGS. FIG. 4 is a flowchart showing a processing procedure for abnormality diagnosis control of the EGR device 40. A series of processing shown in this flowchart is repeatedly executed by the electronic control unit 50 during operation of the diesel engine 10. FIG. 5 is a flowchart showing a processing procedure for forcibly opening the intake throttle valve 22. The series of processes shown in this flowchart is executed when the process proceeds to step S202 in the flowchart shown in FIG. FIG. 6 is a map that defines the relationship between the catalyst temperature TC and the change amount ΔTAD of the opening degree of the intake throttle valve 22.

  As shown in FIG. 4, in this process, first, it is determined whether or not an execution condition for abnormality diagnosis of the EGR device 40 is satisfied (step S201). Here, as the diagnosis execution condition, the elapsed period after the deceleration operation of the diesel engine 10 is started is equal to or longer than a predetermined period, and the abnormality determination of the EGR device 40 is not made by the previous control cycle. Can be mentioned. If the diagnosis execution condition is not satisfied (step S201: “NO”), the series of processes is temporarily terminated.

  On the other hand, when the diagnosis execution condition is satisfied in step S201 (step S201: “YES”), the routine proceeds to a forced opening degree changing process of the intake throttle valve 22 (step S202).

  As shown in FIG. 5, in the forced opening change process of the intake throttle valve 22, first, the catalyst temperature TC at that time is read, and the estimated accumulation amount D of PM in the filter 32a of the exhaust purification catalyst 32 is derived (step). S221). Next, it is determined whether or not the catalyst temperature TC is lower than the predetermined temperature TCth1 (step S222), and it is determined whether or not the estimated PM accumulation amount D is lower than the predetermined amount Dth1 (step S223). The predetermined temperature TCth1 and the predetermined amount Dth1 here are values set in advance through experiments or the like. If the catalyst temperature TC is not less than the predetermined temperature TCth1 in step S223 and the estimated PM accumulation amount D is not less than the predetermined amount Dth1 in step S224 (step S222: “NO”, step S223 “NO”), the next step In addition, the forced drive of the intake throttle valve 22 is prohibited (step S229), and this series of processing ends. That is, in a state where the amount of accumulated PM is somewhat high and the catalyst temperature TC is high to some extent, the air flowing into the exhaust purification catalyst 32 is normally adjusted through the basic opening degree control of the intake throttle valve 22, Thus, the exhaust purification catalyst 32 is cooled. However, if the opening degree of the intake throttle valve 22 is forcibly changed to the closed side at this time, the amount of air flowing into the exhaust purification catalyst 32 is excessively decreased, and the catalyst temperature TC is excessively increased. As a result, the possibility of deterioration of the exhaust purification catalyst 32 increases. Therefore, in the present embodiment, when the opening degree of the intake throttle valve 22 is forcibly changed to the closed side, the catalyst temperature TC rises excessively due to this, and the deterioration of the exhaust purification catalyst 32 progresses. When it is determined that the possibility is high, forcible change of the opening degree of the intake throttle valve 22 is prohibited.

  On the other hand, when the catalyst temperature TC is less than the predetermined temperature TCth1 and the estimated accumulation amount D of PM is less than the predetermined amount Dth1 (step S222: “YES”, step S223 “YES”), FIG. With reference to the map shown, the opening change amount ΔTAD of the intake throttle valve 22 is derived (step S224). In this map, as shown in FIG. 6, the lower the catalyst temperature TC, the larger the opening change amount ΔTAD of the intake throttle valve 22 becomes. In other words, when the opening of the intake throttle valve 22 is closed from the opening TAC controlled by the basic opening degree control during deceleration, the amount of air flowing into the exhaust purification catalyst 32 decreases and the catalyst temperature TC decreases. It becomes difficult to do. Here, when the catalyst temperature TC is relatively low, the opening degree of the intake throttle valve 22 is set to a relatively closed side, thereby suitably suppressing a decrease in the catalyst temperature TC during the deceleration operation of the diesel engine 10. Therefore, the change amount ΔPIM of the intake pipe pressure PIM accompanying the opening / closing of the EGR valve 42 can be made larger. On the other hand, if the opening degree of the intake throttle valve 22 is excessively closed when the catalyst temperature TC is relatively high, the catalyst temperature TC may increase excessively and the exhaust purification catalyst 32 may deteriorate. Here, when the catalyst temperature TC is relatively high, the opening of the intake throttle valve 22 is set to a relatively open side, thereby forcibly changing the opening of the intake throttle valve 22 to the closed side. As a result, it is possible to suppress the catalyst temperature TC from rising excessively, and further, the deterioration of the exhaust purification catalyst 32 from proceeding. In this embodiment, the opening change amount ΔTAD of the intake throttle valve 22 is set based on the same map (see FIG. 6) regardless of the engine speed NE. Here, the relationship that the amount of change ΔPIM of the intake pipe pressure PIM increases as the opening degree of the intake throttle valve 22 is closed becomes greater regardless of the engine speed NE. The magnitude of the change amount ΔPIM of the intake pipe pressure PIM with respect to the opening degree change amount ΔTAD of the intake throttle valve 22 varies depending on the engine speed NE. Accordingly, a map for defining the relationship between the opening change amount ΔTAD of the intake throttle valve 22 and the change amount ΔPIM of the intake pipe pressure PIM is provided for each of a plurality of engine rotational speed regions, and a map corresponding to the engine rotational speed NE. Can be selected as appropriate.

  When the opening change amount ΔTAD of the intake throttle valve 22 is set in this way, next, the engine operating state such as the engine speed NE and the fuel injection amount Q at that time, the vehicle running such as the vehicle speed V and the shift position SHIFT of the automatic transmission, etc. Based on the state, the upper limit value SNDth of the range in which the magnitude of the abnormal noise generated with the forced drive of the intake throttle valve 22 is allowed and the magnitude of the impact generated with the forced drive of the intake throttle valve 22 are allowed. The upper limit value SHKth of the range is derived (step S225). Here, the magnitude of the abnormal noise and the magnitude of the impact caused by factors other than the forced drive of the intake throttle valve 22 are estimated based on the engine operating state and the running state of the vehicle, and the abnormal noise magnitude and the impact thus estimated are estimated. The upper limit values SNDth and SHKth are set so as to increase as the size of. Then, on the basis of the engine operation state such as the engine speed NE and the fuel injection amount Q at that time and the opening change amount ΔTAD of the intake throttle valve 22, abnormal noise generated due to the forced drive of the intake throttle valve 22 is generated. The magnitude SND and the magnitude of shock SHK are each estimated (step S226). Here, the larger the opening change amount ΔTAD of the intake throttle valve 22 is, the larger the noise SND and the shock magnitude SHK are estimated to be larger values. Next, it is determined whether the estimated abnormal noise magnitude SND is less than the upper limit value SNDth and whether the estimated impact magnitude SHK is less than the upper limit value SHKth (step S227). ). As a result, if the estimated abnormal noise magnitude SND is less than the upper limit value SNDth and the estimated impact magnitude SHK is less than the upper limit value SHKth (step S227: “YES”). Then, the intake throttle valve 22 is forcibly driven (step S228), and this series of processing is terminated.

  On the other hand, if the estimated noise magnitude SND is not less than the upper limit value SNDth or the estimated impact magnitude SHK is not less than the upper limit value SHKth (step S227: “NO”), the intake throttle valve 22 is prohibited (step S229), and this series of processing ends. That is, if the intake throttle valve 22 is forcibly driven, there is a risk that abnormal noise or impact generated by the intake throttle valve 22 may be a problem. The larger the noise and impact generated by the above, the smaller the influence of the noise and impact generated by the forced drive of the intake throttle valve 22 on the overall noise and impact. Therefore, in the present embodiment, the magnitudes SND and SHK of both the abnormal noise and the shock that occur due to the forced drive of the intake throttle valve 22 are estimated in advance, and the magnitude of at least one of the estimated abnormal noise and the impact is determined. When the upper limit values SNDth and SHKth of the allowable range are exceeded, forcible change of the opening degree of the intake throttle valve 22 is prohibited. As a result, it is possible to avoid abnormal noise or impact that may be caused by the forced drive of the intake throttle valve 22.

  Incidentally, if the intake throttle valve 22 is forcibly driven when it is suddenly performed, there is a possibility that abnormal noises or impacts caused by this will become a problem. Therefore, in the present embodiment, when the intake throttle valve 22 is forcibly driven, the opening degree of the intake throttle valve 22 is gradually changed. As a result, it is possible to reduce the size of the abnormal noise or impact that occurs when the opening of the intake throttle valve 22 is forcibly changed.

  When the forced opening change process of the intake throttle valve 22 is completed as described above, next, as shown in FIG. 4, the intake pipe pressure at that time, that is, the EGR valve 42 is fully closed. The intake pipe pressure PIMcls in a state where the operation command is output is read (step S203). Next, an operation command for fully opening the EGR valve 42 is output (step S204). Next, the intake pipe pressure PIMopn is read (step S205). When the intake pipe pressures PIMcls and PIMopn are read in this way, next, it is determined whether or not the absolute value ΔPIM (= | PIMcls−PIMopn |) of the deviation of the intake pipe pressures PIMcls and PIMopn is equal to or greater than a predetermined value A1 ( Step S206). The predetermined value A1 here is an abnormality such that the EGR valve 42 is fixed at an intermediate opening degree between the fully closed state and the fully opened state, or the exhaust gas flow area is halved due to the clogging of the EGR passage 41. Is set as a value between the absolute value ΔPIM of the change amount of the intake pipe pressure when the EGR device 40 is generated and the absolute value ΔPIM of the change amount of the intake pipe pressure when it is normal. As a result, when the absolute value ΔPIM of the change amount of the intake pipe pressure is equal to or larger than the predetermined value A1 (step S206: “YES”), it is determined that the EGR device 40 is normal (step S207). This series of processes is temporarily terminated.

  On the other hand, when the absolute value ΔPIM of the change amount of the intake pipe pressure is not equal to or greater than the predetermined value A1 (step S206: “NO”), it is determined that an abnormality has occurred in the EGR device 40 (step S208). This series of processes is temporarily terminated.

According to the control device for a diesel engine according to the present embodiment described above, the following effects can be obtained.
(1) Through the electronic control unit 50, while performing deceleration basic opening degree control for controlling the opening degree of the intake throttle valve 22 to control the catalyst temperature TC during the deceleration operation of the diesel engine 10, the deceleration of the diesel engine 10 is performed. During the operation, the EGR valve 42 is forcibly opened and closed, and the presence or absence of an abnormality in the EGR device 40 is diagnosed based on the absolute value ΔPIM of the change amount of the intake pipe pressure PIM accompanying the opening and closing. Further, when diagnosing abnormality of the EGR device 40, the intake throttle valve 22 is forcibly changed to the opening degree TAD closer to the opening degree TAC than the opening degree TAC controlled by the basic opening degree control during deceleration. Thereby, compared with the case where the diagnosis of the EGR device 40 is performed with the intake throttle valve 22 kept at the opening degree TAC controlled by the basic opening degree control at the time of deceleration, it is normal when the EGR device 40 is abnormal. The degree of divergence of the change amount ΔPIM of the intake pipe pressure PIM with the case can be increased. Therefore, even when the degree of abnormality of the EGR device 40 is small, abnormality diagnosis can be performed with high accuracy.

  (2) Through the electronic control unit 50, the opening degree of the intake throttle valve 22 is set based on the catalyst temperature TC. Specifically, when the catalyst temperature TC is low, the opening degree of the intake throttle valve 22 is set closer to the closing side than when the catalyst temperature TC is high. As a result, the amount of change ΔPIM in the intake pipe pressure PIM that accompanies the opening / closing of the EGR valve 42 can be further increased while suitably suppressing the decrease in the catalyst temperature TC during the deceleration operation of the diesel engine 10. Therefore, the accuracy of abnormality diagnosis of the EGR device 40 can be further improved. In addition, it is possible to suppress the catalyst temperature TC from excessively increasing due to the forced change of the opening of the intake throttle valve 22 to the closed side, and hence the progress of the deterioration of the exhaust purification catalyst 32. It becomes like this.

  (3) Forcibly changing the opening degree of the intake throttle valve 22 is prohibited when the estimated PM accumulation amount D exceeds the predetermined amount Dth1 and the catalyst temperature TC exceeds the predetermined temperature TCth1 through the electronic control unit 50. It was. As a result, it is possible to avoid the catalyst temperature TC from excessively rising due to forcibly changing the opening degree of the intake throttle valve 22 to the closed side, and thus the deterioration of the exhaust purification catalyst 32 from proceeding. become able to.

  (4) Through the electronic control unit 50, the magnitudes SND and SHK of both the abnormal noise and the shock that occur due to the forced change of the opening of the intake throttle valve 22 are estimated in advance, and the estimated abnormal noise and When the magnitude of at least one of the impacts exceeds the upper limits SNDth and SHKth of the allowable range, the forced change of the opening of the intake throttle valve 22 is prohibited. As a result, it is possible to avoid abnormal noise and impact that may be caused by the forced change of the opening of the intake throttle valve 22.

  (5) The upper limit values SNDth and SHKth of the allowable range are set through the electronic control unit 50 based on both the engine operating state and the vehicle traveling state. Thus, the upper limit value can be accurately set according to the magnitude of the influence of the abnormal noise or impact generated by forcibly changing the opening of the intake throttle valve 22 on the overall abnormal noise or impact. become able to.

(6) When the opening degree of the intake throttle valve 22 is forcibly changed through the electronic control unit 50, the opening degree of the intake throttle valve 22 is gradually changed. As a result, it is possible to reduce the size of the abnormal noise or impact that occurs when the opening of the intake throttle valve 22 is forcibly changed.
Second Embodiment
Hereinafter, with reference to FIGS. 7-10, 2nd Embodiment of the control apparatus of the diesel engine which concerns on this invention is described.

  In the present embodiment, the presence / absence of abnormality of the EGR device 40 is diagnosed based on “amount of change ΔGN in intake air amount GN (= GA / NE) per unit engine rotational speed” associated with forced opening / closing of the EGR valve 42. The point that the intake throttle valve 22 is forcibly changed to the opening degree TAD of the “open side” rather than the opening degree TAC controlled by the basic opening degree control at the time of deceleration when the abnormality of the EGR device 40 is diagnosed. This is different from the first embodiment.

Hereinafter, the difference from the first embodiment will be mainly described.
In the present embodiment, the EGR valve 42 is forcibly opened and closed during the deceleration operation of the diesel engine 10 that does not need to execute the EGR control for the combustion control of the diesel engine 10, and the unit engine rotational speed associated with the opening and closing thereof. The amount of change ΔGN of the winning intake air amount GN is obtained, and the presence or absence of an abnormality in the EGR device 40 is diagnosed based on the amount of change ΔGN. Specifically, the intake air amount GNcls per unit engine rotation speed in the state where the operation command for fully closing the EGR valve 42 is output, and the operation command for fully opening the EGR valve 42 are output. A deviation ΔGN (= GNcls−GNopn) with respect to the intake air amount GNpnn per unit engine rotation speed is calculated, and it is determined that an abnormality has occurred in the EGR device 40 when the deviation ΔGN falls below a predetermined value B1. I have to. This is because the amount of change ΔGN of the intake air amount GN per unit engine rotation speed associated with the opening and closing of the EGR valve 42 becomes smaller as the degree of clogging of the EGR passage 41 becomes larger.

  However, as described above, for example, when the operation failure of the EGR valve 42 occurs and the operation range is limited to an opening between the fully closed state and the fully closed and fully open state, or the EGR valve 42 is normal. However, when the degree of abnormality of the EGR device 40 is relatively small as in the case where the exhaust flow area is halved due to clogging of the EGR passage 41, the abnormality diagnosis can be performed accurately for the following reason. Can not. That is, in this case, the degree of divergence of the change amount ΔGN of the intake air amount GN per unit engine rotational speed due to the opening and closing of the EGR valve 42 between the case where the abnormality has occurred and the case where it is normal is small. In addition, since the intake air amount GA and the engine rotational speed NE always change, the intake air amount change ΔGN per unit engine rotational speed also always changes. Therefore, it becomes difficult for a significant difference to occur in the change amount ΔGN of the intake air amount GN per unit engine rotation speed between when the abnormality occurs in the EGR device 40 and when it is normal. As a result, it is diagnosed that the EGR device 40 is normal even though the EGR device 40 is abnormal, or is diagnosed as abnormal even though the EGR device 40 is normal. Diagnosis cannot be made with high accuracy.

  Therefore, in the present embodiment, when the abnormality of the EGR device 40 is diagnosed through the electronic control device 50, the intake throttle valve can be used so that the abnormality diagnosis can be accurately performed even when the degree of abnormality of the EGR device 40 is small. 22 is forcibly changed to the opening degree TAD on the opening side with respect to the opening degree TAC controlled by the basic opening degree control at the time of deceleration.

  Here, the principle of the present invention will be described with reference to FIG. FIG. 7A is a graph showing the relationship between the opening degree TA of the intake throttle valve 22 and the intake air amount GN per unit engine speed, and FIG. 7B is a graph showing the intake throttle valve 22. Is a graph showing the relationship between the degree of opening TA and the amount of change ΔGN of the intake air amount GN per unit engine speed associated with opening and closing of the EGR valve 42. All of these assume the case where the EGR device 40 is normal.

  First, as shown in FIG. 7A, the intake air amount GNpn per unit engine rotation speed when the EGR valve 42 is fully opened is the unit engine rotation when the EGR valve 42 is fully closed. It becomes smaller than the intake air amount GNcls per speed. This is because when the EGR valve 42 is fully opened, the air in the exhaust passage 31 is introduced into the intake passage 21 through the opened EGR valve 42, so that the air passes through the intake throttle valve 22 correspondingly. This is because the amount of air to be discharged, that is, the intake air amount GA detected by the intake air amount sensor 63 is reduced. Here, both the intake air amounts GNpn and GNcls per unit engine rotation speed increase as the opening of the intake throttle valve 22 is opened, but the unit engine with respect to the opening change amount of the intake throttle valve 22 at this time The amount of increase in the intake air amounts GNpn, GNcls per rotation speed is greater when the EGR valve 42 is fully closed than when the EGR valve 42 is fully open. This is because when the EGR valve 42 is fully closed, the air in the exhaust passage 31 is not introduced into the intake passage 21, and the intake throttle valve 22 is opened by the opening degree of the intake throttle valve 22. This is because the amount of air passing through increases. Therefore, as shown in FIG. 7B, the change amount ΔGN of the intake air amount GN per unit engine rotation speed due to the opening and closing of the EGR valve 42 becomes larger as the opening degree of the intake throttle valve 22 is opened. . From this, when the abnormality of the EGR device 40 is diagnosed, the intake throttle valve 22 is forcibly changed to the opening degree TAD on the opening side with respect to the opening degree TAC controlled by the basic opening degree control at the time of deceleration. Compared to the diagnosis of the EGR device 40 with the valve 22 kept at the opening TAC, the intake air amount GN per unit engine rotational speed when the EGR device 40 is abnormal and when it is normal The degree of divergence of the change amount ΔGN can be increased.

  Next, abnormality diagnosis control of the EGR device 40 will be described with reference to FIGS. FIG. 8 is a flowchart showing a processing procedure for abnormality diagnosis control of the EGR device 40. A series of processing shown in this flowchart is repeatedly executed by the electronic control unit 50 during operation of the diesel engine 10. FIG. 9 is a flowchart showing a processing procedure for forcibly opening the intake throttle valve 22. The series of processes shown in this flowchart is executed when the process proceeds to step S302 in the flowchart shown in FIG. FIG. 10 is a map that defines the relationship between the catalyst temperature TC and the change amount ΔTAD of the opening degree of the intake throttle valve 22.

  As shown in FIG. 8, in this process, first, it is determined whether or not an execution condition for abnormality diagnosis of the EGR device 40 is satisfied (step S301). The diagnosis execution conditions here are the same as the conditions exemplified in step S201 in the flowchart of FIG. If the diagnosis execution condition is not satisfied (step S301: “NO”), the series of processes is temporarily terminated.

  On the other hand, when the diagnosis execution condition is satisfied in step S301 (step S301: “YES”), the routine proceeds to a forced opening degree changing process of the intake throttle valve 22 (step S302).

  As shown in FIG. 9, in the forced opening change process of the intake throttle valve 22, first, the catalyst temperature TC at that time is read (step S321). Next, it is determined whether or not the catalyst temperature TC is equal to or higher than a predetermined temperature TCth2 (step S322). The predetermined temperature TCth2 here is a temperature sufficiently lower than the predetermined temperature TCth1 exemplified in the first embodiment (TCth2 << TCth1), and is a value set in advance through experiments or the like. In step S322, if the catalyst temperature TC is not equal to or higher than the predetermined temperature TCth2 (step S322: “NO”), then the forced drive of the intake throttle valve 22 is prohibited (step S325), and this series of processes is performed. Exit. That is, normally, when the opening of the intake throttle valve 22 is opened more than the opening TAC controlled by the basic opening degree control during deceleration, the amount of air flowing into the exhaust purification catalyst 32 increases, so that the catalyst temperature TC Tends to decrease. For this reason, if the opening degree of the intake throttle valve 22 is excessively opened when the catalyst temperature TC is low to some extent, the catalyst temperature TC may be excessively decreased and the exhaust purification efficiency through the exhaust purification catalyst 32 may be excessively decreased. Increases nature. Therefore, in the present embodiment, the catalyst temperature TC is excessively decreased due to forcibly changing the opening of the intake throttle valve 22 to the open side, and thus the exhaust purification efficiency through the exhaust purification catalyst 32 is excessively decreased. When it is determined that there is a high possibility that the intake throttle valve 22 is open, forcible change of the opening of the intake throttle valve 22 is prohibited.

  On the other hand, when the catalyst temperature TC is equal to or higher than the predetermined temperature TCth2 (step S322: “YES”), an opening change amount ΔTAD of the intake throttle valve 22 is derived with reference to a map shown in FIG. (Step S323). In this map, as shown in FIG. 10, the opening degree change amount ΔTAD of the intake throttle valve 22 is set to be larger as the catalyst temperature TC is higher. That is, when the opening of the intake throttle valve 22 is opened more than the opening TAC controlled by the basic opening degree control at the time of deceleration, the amount of air flowing into the exhaust purification catalyst 32 increases and the catalyst temperature TC decreases. It becomes easy to do. Here, when the catalyst temperature TC is relatively high, the opening degree of the intake throttle valve 22 is set to a relatively open side, so that the change in the intake air amount GN per unit engine rotational speed accompanying the opening and closing of the EGR valve 42. The quantity ΔGN can be made larger. Moreover, since the catalyst temperature TC is relatively high, the catalyst temperature TC does not excessively decrease even if the opening degree of the intake throttle valve 22 is forcibly changed to the open side. On the other hand, if the opening degree of the intake throttle valve 22 is excessively opened when the catalyst temperature TC is relatively low, the catalyst temperature TC may be excessively decreased and the exhaust purification efficiency through the exhaust purification catalyst 32 may be decreased. . Here, when the catalyst temperature TC is relatively low, the opening of the intake throttle valve 22 is set to a relatively closed side, thereby forcibly changing the opening of the intake throttle valve 22 to the open side. As a result, it is possible to suppress the catalyst temperature TC from being excessively lowered, and hence the exhaust purification efficiency through the exhaust purification catalyst 32 from being lowered. In this embodiment, the opening change amount ΔTAD of the intake throttle valve 22 is set based on the same map (see FIG. 10) regardless of the engine speed NE. Here, the relationship that the amount of change ΔGN in the intake air amount per unit engine rotational speed increases with the opening and closing of the EGR valve 42 as the opening of the intake throttle valve 22 is opened is related to the engine rotational speed NE. However, the magnitude of the change amount ΔGN of the intake air amount per unit engine rotation speed with respect to the opening change amount ΔTAD of the intake throttle valve 22 differs depending on the engine rotation speed NE. Therefore, a map for defining the relationship between the opening change amount ΔTAD of the intake throttle valve 22 and the intake air amount change amount ΔGN per unit engine rotational speed is provided for each of a plurality of engine rotational speed regions, and the engine rotational speed is set. It is also possible to appropriately select a map corresponding to NE.

When the opening change amount ΔTAD of the intake throttle valve 22 is set in this way, next, the intake throttle valve 22 is forcibly driven (step S324), and this series of processing ends.
Incidentally, if the intake throttle valve 22 is forcibly driven when it is suddenly performed, there is a possibility that abnormal noises or impacts caused by this will become a problem. Therefore, in the present embodiment, when the intake throttle valve 22 is forcibly driven, the opening degree of the intake throttle valve 22 is gradually changed. As a result, it is possible to reduce the size of the abnormal noise or impact that occurs when the opening of the intake throttle valve 22 is forcibly changed.

  When the forced opening change processing of the intake throttle valve 22 is completed as described above, next, as shown in FIG. 8, the engine rotational speed NE and the intake air amount GA at that time, that is, the EGR valve 42 are set. On the other hand, the engine rotational speed NEcls and the intake air amount GAcls in a state where the operation command for fully closing is output are read (step S303). Next, an operation command for fully opening the EGR valve 42 is output (step S304). Next, the engine speed NEopn and the intake air amount GAopn are read (step S305). When the engine speed, NEcls, NEopn, and intake air amounts GAcls, GAopn are read in this way, next, deviation ΔGN (= GAcls / NEcls− It is determined whether or not (GAopn / NEopn) is equal to or greater than a predetermined value B1 (step S306). The predetermined value B1 here is an abnormality such that the EGR valve 42 is fixed at an intermediate opening degree between the fully closed state and the fully opened state, or the exhaust gas flow area is halved due to the clogging of the EGR passage 41. Is set as a value between the change amount ΔGN of the intake air amount per unit engine rotation speed when the EGR device 40 is generated and the change amount ΔGN of the intake air amount per unit engine rotation speed when it is normal Has been. As a result, when the change amount ΔGN of the intake air amount per unit engine speed is equal to or greater than the predetermined value B1 (step S406: “YES”), it is then determined that the EGR device 40 is normal. (Step S407), and this series of processes is temporarily terminated.

  On the other hand, if the change amount ΔGN of the intake air amount per unit engine rotational speed is not equal to or greater than the predetermined value B1 (step S406: “NO”), it is then determined that an abnormality has occurred in the EGR device 40. (Step S208), and this series of processes is temporarily terminated.

According to the control device for a diesel engine according to the present embodiment described above, the following effects can be obtained.
(1) Through the electronic control unit 50, while performing deceleration basic opening degree control for controlling the opening degree of the intake throttle valve 22 to control the catalyst temperature TC during the deceleration operation of the diesel engine 10, the deceleration of the diesel engine 10 is performed. During operation, the EGR valve 42 is forcibly opened and closed, and the presence or absence of an abnormality in the EGR device 40 is diagnosed based on the change amount ΔGN of the intake air amount GN (= GA / NE) per unit engine rotation speed associated with the opening and closing. It was decided. Further, when diagnosing the abnormality of the EGR device 40, the intake throttle valve 22 is forcibly changed to the opening degree TAD on the opening side with respect to the opening degree TAC controlled by the basic opening degree control during deceleration. As a result, the amount of change ΔGN in the intake air amount GN per unit engine rotation speed is compared with the case where the diagnosis of the EGR device 40 is performed with the intake throttle valve 22 kept at the opening degree TAC controlled by the basic opening degree control at the time of deceleration. The degree of divergence of can be made large. Therefore, even when the degree of abnormality of the EGR device 40 is small, abnormality diagnosis can be performed with high accuracy.

  (2) Through the electronic control unit 50, the opening degree of the intake throttle valve 22 is set based on the catalyst temperature TC. Specifically, the opening degree of the intake throttle valve 22 is set to the open side when the catalyst temperature TC is high compared to when the catalyst temperature TC is low. Thus, when the catalyst temperature TC is relatively high, the opening degree of the intake throttle valve 22 is set to a relatively open side, so that the amount of change in the intake air amount GN per unit engine speed due to the opening and closing of the EGR valve 42 is set. ΔGN can be further increased. Moreover, since the catalyst temperature TC is relatively high, the catalyst temperature TC does not excessively decrease even if the opening degree of the intake throttle valve 22 is forcibly changed to the open side. Therefore, the accuracy of abnormality diagnosis of the EGR device 40 can be further improved. Further, when the catalyst temperature TC is relatively low, the opening degree of the intake throttle valve 22 is set to the relatively closed side, and therefore, the opening degree of the intake throttle valve 22 is forcibly changed to the open side. It is possible to suppress the catalyst temperature TC from being excessively lowered, and hence the exhaust purification efficiency through the exhaust purification catalyst 32 from being lowered.

  (3) When the catalyst temperature TC is lower than the predetermined temperature TCth2 through the electronic control unit 50, the forced change of the opening degree of the intake throttle valve 22 is prohibited. As a result, the catalyst temperature TC is excessively decreased due to forcibly changing the opening of the intake throttle valve 22 to the open side, and the exhaust purification efficiency through the exhaust purification catalyst 32 is excessively decreased. Will be able to avoid.

  In addition, the control apparatus of the diesel engine concerning this invention is not limited to the structure illustrated in the said embodiment, For example, it can also implement as the following forms which changed this suitably.

  In each of the above embodiments, the deviation ΔPIM of the intake pipe pressure PIM accompanying the forced opening / closing of the EGR valve 42 and the deviation ΔGN of the intake air amount GN per unit engine rotation speed accompanying the forced opening / closing of the EGR valve 42 are set. An example of performing an abnormality diagnosis of the EGR device 40 based on the above is illustrated. However, the diagnostic aspect of the diagnostic means according to the present invention is not limited to this. In addition, for example, the EGR device 40 is based on the ratio of the intake pipe pressure PIM associated with the forced opening / closing of the EGR valve 42 or the ratio of the intake air amount GN per unit engine rotational speed associated with the forced opening / closing of the EGR valve 42. The abnormality diagnosis may be performed.

  In each of the above embodiments, in the abnormality diagnosis of the EGR device 40, the operation command for fully closing the EGR valve 42 is forcibly changed from the state in which the operation command for full opening is made. However, instead of this, from the state in which the operation command for the predetermined opening degree that is closer to the open side than the fully closed state is given, the operation command for the predetermined opening degree that is closer to the open side than the fully open state is issued. You may make it switch to the state currently made compulsorily.

  -As in the first embodiment, when the opening degree of the intake throttle valve 22 is forcibly changed, gradually changing the opening degree of the intake throttle valve 22 forces the opening degree of the intake throttle valve 22 This is desirable in order to reduce the size of the abnormal noise and impact generated with the change. However, the opening degree of the intake throttle valve 22 may be abruptly changed when the amount of noise or impact generated can be ignored, for example, when the opening degree change amount ΔTAD of the intake throttle valve 22 is small. . In addition, the opening degree of the intake throttle valve can always be suddenly changed if there is no problem with the size of the generated abnormal noise or impact.

  In the first embodiment, the upper limit values SNDth and SHKth within the range in which the abnormal noise and the magnitude of impact that are generated by the forced drive of the intake throttle valve 22 are allowed are set in both the engine operating state and the vehicle traveling state. The variable setting is made based on this. However, the forcible change means according to the present invention is not limited to this. For example, if the diesel engine is not mounted on the vehicle, the upper limit values SNDth and SHKth are variably set based only on the engine operating state. do it.

  In the first embodiment, the upper limit values SNDth and SHKth of the allowable ranges are variably set based on the engine operating state and the vehicle traveling state, but the forcible changing means according to the present invention is limited to this. These upper limit values SNDth and SHKth can be fixed values.

  In the first embodiment, the magnitudes SND and SHK of both the abnormal noise and the shock that occur due to the forced change of the opening of the intake throttle valve 22 are estimated in advance, and the estimated abnormal noise and shock are estimated. When at least one of the values exceeds the upper limit values SNDth and SHKth of the allowable range, the forced change of the opening of the intake throttle valve 22 is prohibited. However, the forcible change means according to the present invention is not limited to this, and the opening degree of the intake throttle valve 22 is forcibly only when the abnormal noise and the magnitude of impact exceed both the upper limit values SNDth and SHKth of the allowable range. Changes may be prohibited. Further, for example, only the abnormal noise magnitude SND that occurs due to the forced change of the opening of the intake throttle valve 22 is estimated in advance, and the estimated abnormal noise magnitude exceeds the upper limit value SNDth of the allowable range. In this case, forcible change of the opening degree of the intake throttle valve 22 may be prohibited. In addition, these configurations can be applied in the second embodiment, and in the first embodiment, these configurations can be omitted as in the second embodiment.

  The amount of change ΔPIM in the intake pipe pressure PIM that accompanies opening and closing of the EGR valve 42 increases as the opening of the intake throttle valve 22 is closed. Further, as the opening degree of the intake throttle valve 22 is increased, the change amount ΔGN of the intake air amount GN per unit engine rotation speed associated with the opening / closing of the EGR valve 42 becomes larger. However, the relationship between the opening degree of the intake throttle valve 22 and the change amount ΔPIM of the intake pipe pressure PIM, and the relationship between the opening degree of the intake throttle valve 22 and the change amount ΔGN of the intake air amount GN per unit engine speed. Is different depending on the state of the external environment of the diesel engine 10 such as outside air temperature or atmospheric pressure. Further, for example, the manner in which the temperature of the exhaust purification catalyst 32 changes and the magnitude of the noise and impact that occur when the intake throttle valve 22 is forcibly driven also vary depending on the state of the external environment of the diesel engine 10 such as the outside air temperature and atmospheric pressure. It becomes. Therefore, if the opening degree of the intake throttle valve 22 is set based on the external environment state of the diesel engine 10 such as the outside air temperature or atmospheric pressure, the opening degree of the intake throttle valve 22 is forcibly changed. At this time, the target opening degree of the intake throttle valve can be set accurately.

  In the first embodiment, when the estimated PM accumulation amount D exceeds the predetermined amount Dth1 and the catalyst temperature TC exceeds the predetermined temperature TCth1, forcibly changing the opening of the intake throttle valve 22 is prohibited. Thus, it is avoided to excessively increase the catalyst temperature TC due to forcibly changing the opening of the intake throttle valve 22 to the closed side, and thus the deterioration of the exhaust purification catalyst 32 proceeds. Yes. However, the forcible change means according to the present invention is not limited to this. For example, when the estimated accumulation amount D of PM exceeds a predetermined amount Dth1, the intake throttle is increased as the estimated accumulation amount D of PM is larger. The opening degree change amount ΔTAD of the valve 22 can be set small. Even in this case, the catalyst temperature TC rises excessively due to forcibly changing the opening of the intake throttle valve 22 to the closed side, and further deterioration of the exhaust purification catalyst 32 proceeds. It will be possible to avoid.

  In each of the above embodiments, the regeneration control of the filter 32a of the exhaust purification catalyst 32 and the relationship between the regeneration control and the forced drive of the intake throttle valve 22 are not shown, but based on the control state of the regeneration control of the filter 32a. The opening degree of the intake throttle valve 22 may be set.

Hereinafter, an example of the mode of forced driving of the intake throttle valve 22 based on the control state of the regeneration control of the filter 32a will be described.
When the amount of PM collected by the filter 32a of the exhaust purification catalyst 32 becomes excessive, the back pressure of the diesel engine 10 increases due to clogging of the filter. Therefore, when the estimated PM accumulation amount D exceeds a predetermined amount, regeneration control for removing the particulate matter deposited on the filter 32a and preventing clogging is executed. In this regeneration control, so-called post-injection is performed in which fuel that does not contribute to combustion is injected into the combustion chamber 12 during the expansion stroke or exhaust stroke of the diesel engine 10. Alternatively, a fuel addition valve is provided in the exhaust passage 31 on the exhaust upstream side of the exhaust purification catalyst 32, and fuel is injected from the fuel addition valve into the exhaust passage 31. Then, an unburned fuel component serving as a reducing agent is supplied to the filter 32a to cause an exothermic reaction on the NOx catalyst, thereby increasing the catalyst temperature TC. By increasing the catalyst temperature TC in this way, the NOx catalyst is activated and the oxidation reaction of PM on the NOx catalyst is promoted, so that the particulate matter deposited on the filter 32a is burned and removed. Can do.

  Here, in the configuration in which the opening degree of the intake throttle valve 22 is set closer to the opening degree TAC controlled by the basic opening degree control during deceleration, the opening degree of the intake throttle valve 22 is forcibly changed. The amount of air flowing into the exhaust purification catalyst 32 will decrease. Accordingly, if the opening degree of the intake throttle valve 22 is forcibly changed while the temperature of the exhaust purification catalyst 32 is being raised by regeneration control, the temperature rise of the exhaust purification catalyst 32 is preferably promoted.

  On the other hand, in the configuration in which the opening degree of the intake throttle valve 22 is opened more than the opening degree TAC controlled by the basic opening degree control at the time of deceleration, the exhaust gas is exhausted with the forced change of the opening degree of the intake throttle valve 22. Since the amount of air flowing into the purification catalyst 32 increases, if the opening degree of the intake throttle valve 22 is forcibly changed when the temperature of the exhaust purification catalyst 32 is raised through regeneration control, the exhaust purification catalyst 32 will rise. There exists a possibility that temperature may not advance suitably. Therefore, when the temperature of the exhaust purification catalyst 32 is raised through the regeneration control, the opening degree of the intake throttle valve 22 is set to the closed side as compared with the case where it is not. As a result, it is possible to suppress the temperature increase of the exhaust purification catalyst 32 from proceeding favorably due to forcibly changing the opening of the intake throttle valve 22 to the open side. Alternatively, forcibly changing the opening of the intake throttle valve 22 is prohibited when the temperature of the exhaust purification catalyst 32 is raised through regeneration control. As a result, it is possible to avoid that the temperature increase of the exhaust purification catalyst 32 does not proceed favorably due to forcibly changing the opening of the intake throttle valve 22 to the open side. The fuel injection valve 13 and the fuel addition valve that perform post injection correspond to the temperature raising agent supply means according to the present invention, and the unburned fuel component supplied from the fuel injection valve 13 and the fuel addition valve relates to the present invention. It corresponds to a temperature raising agent.

  In the first embodiment, when the estimated PM accumulation amount D exceeds the predetermined amount Dth1 and the catalyst temperature TC exceeds the predetermined temperature TCth1, forcibly changing the opening of the intake throttle valve 22 is prohibited. However, instead of this, when the catalyst temperature TC is higher than the predetermined temperature TCth1 regardless of the estimated accumulation amount D of PM, forcibly changing the opening of the intake throttle valve 22 is prohibited. May be. That is, the configuration for estimating the PM accumulation amount D may be omitted. Even in this case, the catalyst temperature TC rises excessively due to forcibly changing the opening of the intake throttle valve 22 to the closed side, and further deterioration of the exhaust purification catalyst 32 proceeds. It will be possible to avoid.

  In each of the above embodiments, during deceleration operation of the diesel engine 10, the basic opening control at the time of deceleration, that is, the control processing (particularly, step S104 to step S107) of the flowchart shown in FIG. 2 is performed. The configuration of the intake throttle valve control means according to the present invention is not limited to this. In short, what is necessary is just to control the opening degree of the intake throttle valve so as to control the temperature of the exhaust purification catalyst during the deceleration operation of the diesel engine.

  The first embodiment exemplifies the case where the abnormality diagnosis of the EGR device 40 is performed based only on the change degree of the intake pipe pressure accompanying the forced opening / closing of the EGR valve 42, and the EGR valve is used in the second embodiment. An example in which abnormality diagnosis of the EGR device 40 is performed based only on the degree of change in the intake air amount per unit engine rotational speed accompanying the forced opening and closing of 42 is shown. However, the diagnostic means according to the present invention is not limited to this, and may include both of the diagnostic means exemplified in these embodiments. In this case, the change mode of the opening degree of the intake throttle valve 22 is set based on at least one of the state of the exhaust purification catalyst 32, the state of the external environment of the diesel engine 10, and the engine operating state. That's fine. In this way, by taking into account at least one of the state of the exhaust purification catalyst 32, the state of the external environment of the diesel engine 10, and the engine operating state, the intake throttle valve such as the direction and amount of change of the opening degree of the intake throttle valve 22 is taken into account. It is possible to accurately set the change mode of the opening degree of 22.

  In the first embodiment, the opening degree of the intake throttle valve 22 is set based on the catalyst temperature TC, but the configuration of the forcible changing means according to the present invention is not limited to this. In short, what is necessary is that the intake throttle valve is forcibly changed to an opening closer to the closing side than the opening controlled by the intake throttle valve control means in the diagnosis by the diagnosis means.

  In the second embodiment, the opening degree of the intake throttle valve 22 is set based on the catalyst temperature TC. However, the configuration of the forced change unit according to the present invention is not limited to this. In short, it is only necessary that the intake throttle valve is forcibly changed to an opening on the opening side with respect to the opening controlled by the intake throttle valve control means in the diagnosis by the diagnosis means.

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 11 ... Engine main body, 12 ... Combustion chamber, 13 ... Fuel injection valve, 21 ... Intake passage, 22 ... Intake throttle valve, 31 ... Exhaust passage, 32 ... Exhaust purification catalyst, 32a ... Filter, 40 ... EGR , 41 ... EGR passage, 42 ... EGR valve, 50 ... electronic control device (intake throttle valve control means, diagnostic means, forced change means, accumulation amount estimation means), 61 ... engine speed sensor, 62 ... accelerator opening sensor , 63 ... intake air amount sensor, 64 ... intake throttle valve opening sensor, 65 ... intake pipe pressure sensor, 66 ... catalyst temperature sensor, 67 ... vehicle speed sensor, 68 ... shift position sensor.

Claims (15)

An intake throttle valve that is provided in the intake passage to change the flow area of intake air, an exhaust purification catalyst that is provided in the exhaust passage and purifies exhaust, an EGR passage for introducing exhaust gas from the exhaust passage into the intake passage, and the same The intake throttle valve is applied to a diesel engine provided with an EGR device including an EGR valve provided in a passage and having a variable exhaust flow area, and controls the temperature of the exhaust purification catalyst during a deceleration operation of the diesel engine. An intake throttle valve control means for controlling the opening degree of the engine, and whether or not the EGR valve is forcibly opened and closed during the deceleration operation of the diesel engine and whether or not the EGR device is abnormal based on the degree of change in the intake pipe pressure accompanying the opening and closing A diesel engine control device comprising:
For diagnosis by the diagnostic means, comprising a forcible change means for forcibly changing the intake throttle valve to an opening closer to the closing side than the opening controlled by the intake throttle valve control means ;
The control device for a diesel engine, wherein the forcible change means sets a change mode of the opening degree of the intake throttle valve based on a state of the exhaust purification catalyst . The control device for a diesel engine according to claim 1 ,
The control device for a diesel engine, wherein the forcible change means sets a change mode of the opening degree of the intake throttle valve based on a temperature of the exhaust purification catalyst. The control device for a diesel engine according to claim 2 ,
The forced modification means, the control device of the diesel engine, wherein the setting the opening degree of the intake throttle valve to the closing side than when higher when temperature before Symbol exhaust purification catalyst is low. In the control apparatus of the diesel engine according to claim 2 or claim 3 ,
The forced change means, when the temperature of the pre-Symbol exhaust purification catalyst is higher than a predetermined temperature, the control device of the diesel engine, characterized in that prohibiting forced change of the opening degree of the intake throttle valve. The control device for a diesel engine according to any one of claims 1 to 4,
Comprising a temperature raising agent supply means for supplying a temperature raising agent to the exhaust purification catalyst;
The control device for a diesel engine, wherein the forcible change means sets a change mode of the opening degree of the intake throttle valve based on a control state of the temperature raising agent supply means. The control device for a diesel engine according to claim 5 ,
The diesel engine characterized in that the forcible change means sets the opening of the intake throttle valve to a closed side when the temperature of the exhaust purification catalyst is raised by the temperature raising agent supply means compared to when the temperature is not Control device. The control device for a diesel engine according to any one of claims 1 to 6,
A deposition amount estimating means for estimating the amount of particulate matter deposited on the exhaust purification catalyst;
The control device for a diesel engine, wherein the forcible change means sets the opening of the intake throttle valve based on the accumulation amount of the particulate matter estimated by the accumulation amount estimation means. The control device for a diesel engine according to claim 7 ,
The forced change section deposition amount of the particulate matter estimated by the pre-Symbol accumulation amount estimating means exceeds a predetermined amount, and the when the temperature of the exhaust purification catalyst is above the predetermined temperature, the opening degree of the intake throttle valve A control device for a diesel engine characterized by prohibiting forced change of the engine. In the control apparatus of the diesel engine as described in any one of Claims 1-8 ,
The said forced change means sets the change aspect of the opening degree of the said intake throttle valve based on the state of the external environment of a diesel engine. The control apparatus of the diesel engine characterized by the above-mentioned. The control device for a diesel engine according to claim 9 ,
The control device for a diesel engine, wherein the forcible change means sets a change mode of the opening degree of the intake throttle valve based on an outside air temperature. In the control apparatus of the diesel engine as described in any one of Claims 1-10 ,
The control device for a diesel engine, wherein the forcible change means sets a change mode of the opening degree of the intake throttle valve based on an engine speed. The control device for a diesel engine according to any one of claims 1 to 11,
The forcible change means preliminarily estimates the magnitude of at least one of an abnormal noise and an impact that occur due to a forced change in the opening of the intake throttle valve, and at least one of the estimated abnormal noise and an impact. A control device for a diesel engine, wherein when the size exceeds an upper limit value of an allowable range, forcibly changing the opening of the intake throttle valve is prohibited. The control device for a diesel engine according to claim 12 ,
The said forced change means sets the upper limit of the said tolerance | permissible_range based on an engine operation state. The control apparatus of the diesel engine characterized by the above-mentioned. The control device for a diesel engine according to claim 12 or claim 13 ,
The diesel engine is mounted on the vehicle,
The said forced change means sets the upper limit of the said tolerance | permissible_range based on the driving state of a vehicle. The control apparatus of the diesel engine characterized by the above-mentioned. The control device for a diesel engine according to any one of claims 1 to 14,
The control device for a diesel engine, wherein the forcible change means gradually changes the opening of the intake throttle valve when forcibly changing the opening of the intake throttle valve.

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