JP2010236516A - Abnormality diagnostic device of exhaust recirculation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality diagnostic device of an exhaust recirculation device executing abnormality diagnosis without causing an excessive temperature rise of an exhaust purifying catalyst and instability of combustion. <P>SOLUTION: This EGR device includes an EGR passage connecting an intake system and an exhaust system of an engine, and an EGR valve provided in the EGR passage for controlling the EGR flow rate returned from the exhaust system to the intake system. The exhaust system includes the exhaust purifying catalyst. When an execution condition of abnormality diagnosis of the EGR device is established, after the EGR valve is temporary driven to close (step S210), it is started to be driven to open (step S240). Assuming that a change amount ΔFegr of the EGR flow rate accompanying opening drive of the EGR valve is a determination value ΔFegrp or more, and it its determined that abnormality is not occurring in the EGR device (step S290), forcible drive of the EGR valve is interrupted, and the opening of the EGR valve is set to an opening based on the engine operation state (step S300). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis device for diagnosing the presence or absence of an abnormality in an exhaust gas recirculation device that recirculates part of exhaust gas in an exhaust system to an intake system.

  In an exhaust gas recirculation device for an internal combustion engine, for example, as described in Patent Document 1, by changing the opening degree of an exhaust gas recirculation valve provided in an exhaust gas recirculation passage, the recirculation amount of exhaust gas is an amount suitable for the engine operating state. I try to control it.

  By the way, in the exhaust gas recirculation device as described above, abnormalities such as malfunction of the exhaust gas recirculation valve and blockage of the exhaust gas recirculation passage may occur. In this case, the exhaust gas recirculation amount is set to an appropriate amount corresponding to the engine operating state. It becomes difficult to control.

  Therefore, in order to diagnose the presence or absence of such an abnormality, for example, in the one described in Patent Document 1, an abnormality diagnosis is performed as follows. That is, in this abnormality diagnosis, when the internal combustion engine is in idling operation, the exhaust gas recirculation valve is forcibly opened, and the amount of change in the exhaust gas recirculation amount that accompanies this open driving is calculated. Is determined to be less than or equal to the determination value, it is diagnosed that an abnormality has occurred in the exhaust gas recirculation device.

JP-A-9-158787

  However, if the opening of the exhaust gas recirculation valve is forcibly opened from the opening set in accordance with the engine operating state in this way, the exhaust gas recirculation amount will increase if there is no abnormality in the exhaust gas recirculation device. As the intake air amount is decreased, the temperature of the intake air including the exhaust gas to be recirculated increases. For this reason, the temperature of the exhaust gas flowing into the exhaust purification catalyst provided in the exhaust system also increases, and the exhaust purification catalyst may excessively increase in temperature. Further, when there is an acceleration request while the exhaust gas recirculation valve is forced to open, and the engine load increases, the exhaust gas recirculation valve is driven to close to increase the intake air amount, but there is a response delay. For this reason, the intake air amount is temporarily insufficient and the combustion becomes unstable, and drivability may be deteriorated or smoke may be generated. In particular, such inconvenience is likely to occur in an environment where the density of intake air is low, such as at high altitudes.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an abnormality of the exhaust gas recirculation device that can perform an abnormality diagnosis without causing an excessive temperature rise or combustion instability of the exhaust purification catalyst. It is to provide a diagnostic device.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is provided in the exhaust gas recirculation passage connecting the intake system of the on-vehicle internal combustion engine and the exhaust system provided with the exhaust purification catalyst, and is returned from the exhaust system to the intake system. An exhaust gas recirculation device having an exhaust gas recirculation valve that adjusts the exhaust gas recirculation amount. In the abnormality diagnosis device for an exhaust gas recirculation device that diagnoses the presence or absence of abnormality, the exhaust gas recirculation device is executed when an abnormality diagnosis execution condition is satisfied. A valve drive means for executing a forced drive process of driving the valve once closed and then opening, a change amount detection means for detecting a change amount of the exhaust gas recirculation amount accompanying the drive of the exhaust gas recirculation valve during the forced drive process; Diagnosing means for diagnosing that there is no abnormality when the amount of change in the exhaust gas recirculation amount due to the open driving of the exhaust gas recirculation valve in the forced drive processing is greater than or equal to a predetermined determination value, the valve drive means comprising the diagnostic hand When the exhaust gas recirculation valve is driven so that the opening degree of the exhaust gas recirculation valve becomes an opening degree based on the engine operating state by interrupting the forcible driving process when diagnosis of no abnormality is made by To do.

  In the above configuration, the exhaust gas recirculation valve is once closed and then opened, and when the amount of change in the exhaust gas recirculation amount due to the open driving is equal to or greater than a predetermined determination value, it is diagnosed that there is no abnormality and there is no abnormality When the diagnosis is made, the forced drive process is interrupted, and the exhaust gas recirculation valve is driven so that the opening degree of the exhaust gas recirculation valve becomes an opening degree set based on the engine operating state. For this reason, the abnormality diagnosis is performed at a stage where the opening degree of the exhaust gas recirculation valve is relatively small, compared to the case where the exhaust gas recirculation valve is simply opened from the opening degree based on the engine operating state and the abnormality diagnosis of the exhaust gas recirculation apparatus is executed. It can be completed. Further, when the abnormality diagnosis of the exhaust gas recirculation device is completed in this way, the opening degree of the exhaust gas recirculation valve is promptly changed to an opening degree set based on the engine operating state. Therefore, the exhaust gas recirculation valve is not opened more than necessary when the abnormality diagnosis is performed, and excessive exhaust gas recirculation is suppressed. Therefore, the abnormality diagnosis can be executed without causing an excessive temperature rise of the exhaust purification catalyst or instability of combustion.

  According to a second aspect of the present invention, in the abnormality diagnosis device for the exhaust gas recirculation apparatus according to the first aspect, the diagnosis means is configured to drive the exhaust gas recirculation valve to be closed prior to the abnormality diagnosis when the exhaust gas recirculation valve is opened. When the amount of change in the exhaust gas recirculation amount is equal to or greater than a predetermined determination value, it is diagnosed that there is no abnormality, and when the valve driving means is diagnosed as having no abnormality in the abnormality diagnosis when the diagnostic means is closed, The forced drive process is interrupted and the exhaust gas recirculation valve is driven so that the opening degree of the exhaust gas recirculation valve is set based on the engine operating state. The gist of the present invention is to continue the forcible driving process so as to execute an abnormality diagnosis at the time of open driving.

  As described above, when the opening degree of the exhaust gas recirculation valve is increased at the time of abnormality diagnosis, the temperature of the intake air including the exhaust gas rises, so the temperature of the exhaust gas flowing into the exhaust gas purification catalyst also rises and the temperature of the exhaust gas purification catalyst excessively increases. There is a fear. On the other hand, if the opening degree of the exhaust gas recirculation valve is reduced, the exhaust gas recirculation amount decreases, and the temperature of the exhaust gas flowing into the exhaust gas purification catalyst is lowered. Therefore, there is a concern that the temperature of the exhaust gas purification catalyst is lowered.

  In this regard, according to the above-described configuration, the abnormality diagnosis of the exhaust gas recirculation device is executed even when the exhaust gas recirculation valve is closed before the abnormality diagnosis during the open driving. When the exhaust gas recirculation apparatus is diagnosed as having no abnormality during the abnormality diagnosis during the closed drive, the forced recirculation valve opening degree is stopped without interrupting the forced drive process and further driving the exhaust gas recirculation valve to be closed. Is quickly changed to the opening degree set based on the engine operating state. For this reason, the time required for abnormality diagnosis can be shortened, and the temperature drop of the catalyst can be suppressed.

  In addition, when the opening degree of the exhaust gas recirculation valve before executing the forced drive processing, that is, the opening degree of the exhaust gas recirculation valve set based on the engine operating state is small, the change in the exhaust gas recirculation amount accompanying the closing drive of the exhaust gas recirculation valve The amount becomes smaller. For this reason, even when there is no abnormality in the exhaust gas recirculation device, there is a case where no abnormality is diagnosed in the abnormality diagnosis during the closed drive. However, in such a case, it can be diagnosed that there is no abnormality in the abnormality diagnosis performed when the exhaust gas recirculation valve is opened thereafter. It should be noted that the determination value used for the abnormality diagnosis during the closed drive and the determination value used for the abnormality diagnosis during the open drive may be set to the same value or different values.

  According to a third aspect of the present invention, in the exhaust gas recirculation apparatus abnormality diagnosis device according to the first or second aspect, the valve driving means performs a predetermined operation after the exhaust recirculation valve is once closed and closed during the forced drive processing. The gist of the invention is to further open the drive until reaching the upper limit opening, and further include setting means for variably setting the upper limit opening and the determination value according to the traveling environment of the vehicle.

  For example, when performing an abnormality diagnosis with a fuel cut during deceleration as an execution condition, the abnormality diagnosis is interrupted when the fuel cut is stopped due to an acceleration request, so the exhaust gas recirculation valve is set based on the engine operating state It is controlled so as to have an opening. Here, since there is a response delay from when the abnormality diagnosis is interrupted until the exhaust gas recirculation amount becomes an amount suitable for the engine operation state, the exhaust gas exceeding the amount suitable for the engine operation state during this response delay period There is a risk of reflux. In particular, in an environment with low air density, such as high altitudes, the amount of intake air that is introduced into the cylinder is smaller than that on flat land, and thus misfire may occur if excessive exhaust gas recirculation is performed as described above. is there.

  In this regard, according to the above configuration, since the upper limit opening degree when the exhaust gas recirculation valve is opened is set according to the traveling environment of the vehicle, for example, when the vehicle is traveling in a highland where the air density is low. However, it is possible to suppress misfire as described above by performing abnormality diagnosis in a state where the upper limit opening is set small and the exhaust gas recirculation amount is limited.

  In the above configuration, in addition to variably setting the upper limit opening of the exhaust gas recirculation valve in accordance with the traveling environment of the vehicle, the determination value used for the abnormality diagnosis is also variable in accordance with the traveling environment of the vehicle. I am trying to set it. For this reason, for example, when the vehicle is traveling on a high altitude or the like, the upper limit opening degree of the exhaust gas recirculation valve is set to be small and the determination value is set to be small so that the abnormality diagnosis of the exhaust gas recirculation device can be appropriately executed. It becomes possible.

  According to a fourth aspect of the present invention, in the abnormality diagnosis device for the exhaust gas recirculation apparatus according to the third aspect, the setting means includes an atmospheric pressure detecting means for detecting an atmospheric pressure as a traveling environment of the vehicle, and the atmospheric pressure detecting means The gist of the invention is to variably set the upper limit opening and the determination value so that the lower the atmospheric pressure detected by (1), the smaller the upper limit opening and the determination value.

  According to the above configuration, it can be determined based on the fact that the atmospheric pressure is low that the vehicle is traveling on a highland. And, when the atmospheric pressure is lower, the upper limit opening degree and the judgment value of the exhaust gas recirculation valve are variably set so that the exhaust gas is suppressed while suppressing misfire even when the vehicle travels on high altitude. An abnormality diagnosis of the reflux device can be executed.

  According to a fifth aspect of the present invention, in the exhaust gas recirculation apparatus abnormality diagnosis device according to the first or second aspect, the valve driving means performs a predetermined operation after the exhaust recirculation valve is once closed and closed during the forced driving process. The gist of the invention is to further open the drive to an upper limit opening, and further include setting means for variably setting the upper limit opening and the determination value according to the operating state of the in-vehicle internal combustion engine.

  According to the above configuration, the upper limit opening when the exhaust gas recirculation valve is opened is set according to the operating state of the in-vehicle internal combustion engine. Even if the catalyst regeneration process that temporarily raises the temperature is performed before the start of the abnormality diagnosis, the abnormality diagnosis is performed with the upper limit opening set small and the exhaust gas recirculation amount limited. The abnormality diagnosis can be executed while suppressing the temperature of the exhaust purification catalyst from rising more than necessary.

  In the above configuration, the upper limit opening of the exhaust gas recirculation valve is variably set according to the operating state of the in-vehicle internal combustion engine, and the determination value used for the abnormality diagnosis is also set in the operating state of the in-vehicle internal combustion engine. Variable settings are made accordingly. For this reason, for example, even when the catalyst regeneration process is executed before the start of the abnormality diagnosis, the exhaust gas recirculation is set by setting the upper limit opening of the exhaust gas recirculation valve to a small value and setting the above determination value small. It is possible to properly execute the abnormality diagnosis of the apparatus.

  The invention according to claim 6 is the abnormality diagnosis device for the exhaust gas recirculation apparatus according to claim 5, wherein the setting means raises the temperature of the exhaust purification catalyst to restore the purification function of the exhaust purification catalyst. When the regeneration process is executed prior to the abnormality diagnosis, the gist is to variably set these so that the upper limit opening and the determination value become smaller.

  According to the above configuration, even if the catalyst regeneration process is performed before the start of the abnormality diagnosis, misfire can be performed by variably setting these so that the upper limit opening degree and the determination value of the exhaust gas recirculation valve become small. It is possible to appropriately execute the abnormality diagnosis of the exhaust gas recirculation device while suppressing the above.

  The invention according to claim 7 is the abnormality diagnosis apparatus for the exhaust gas recirculation apparatus according to any one of claims 1 to 6, further comprising temperature detection means for detecting a temperature of the exhaust purification catalyst, wherein the valve drive The means sets the drive mode of the exhaust gas recirculation valve based on the detected temperature of the exhaust purification catalyst so that the temperature of the exhaust purification catalyst changes in a predetermined temperature range during the forced drive processing. To do.

  According to the above configuration, by setting the driving mode of the exhaust gas recirculation valve when executing the forced driving process based on the temperature of the exhaust purification catalyst, the temperature of the exhaust purification catalyst is changed within a predetermined temperature range. Yes. Therefore, an excessive temperature rise or temperature drop of the exhaust purification catalyst can be suppressed. When estimating the temperature of the exhaust purification catalyst, the temperature may be detected directly, or the temperature may be detected indirectly based on the engine operating state.

  According to an eighth aspect of the present invention, in the abnormality diagnosis device for the exhaust gas recirculation apparatus according to the seventh aspect, the valve drive means has a predetermined opening degree after completing the closed drive of the exhaust gas recirculation valve during the forced drive processing. The opening operation is started after holding the opening until the holding period elapses, and the opening holding period is changed as the detected temperature of the exhaust purification catalyst is lower. Is the gist.

  Here, when the exhaust gas recirculation valve is once closed and then immediately opened, there is a response delay in the change in the exhaust gas recirculation amount, so that the exhaust gas recirculation amount corresponds to the opening after the closed drive. The exhaust gas recirculation valve may be driven to open before the amount drops. For this reason, in consideration of such a response delay of the exhaust gas recirculation amount, it is desirable to maintain the opening degree until the predetermined opening degree holding period has elapsed after completing the closing driving of the exhaust gas recirculation valve as described above. . However, if the opening after the closing drive is maintained in this way, the state in which the opening of the exhaust gas recirculation valve is reduced, that is, the state in which the exhaust gas temperature is lowered continues, so depending on the temperature condition of the exhaust purification catalyst There is a concern that the temperature will drop more than necessary. Therefore, it is desirable to suppress a decrease in the temperature of the exhaust purification catalyst, particularly in a situation where the temperature of the exhaust purification catalyst is low, such as at the start of engine operation or low load operation.

  In this regard, in the configuration according to claim 8, the opening degree holding period for holding the opening degree from the completion of the closing driving of the exhaust gas recirculation valve until the start of the opening driving becomes shorter as the temperature of the exhaust purification catalyst becomes lower. This is changed so that the exhaust gas recirculation valve is driven based on the opening degree holding period after the change. Therefore, the temperature reduction of the exhaust purification catalyst can be appropriately suppressed according to the temperature of the exhaust purification catalyst. Note that if the opening degree holding period is changed to be shorter, the amount of change in the exhaust gas recirculation amount may be reduced. Therefore, it is desirable to set the determination value used for abnormality diagnosis to a small value in consideration of this. .

  According to a ninth aspect of the present invention, in the abnormality diagnosis device for the exhaust gas recirculation apparatus according to the seventh or eighth aspect, the valve driving means is configured to perform the operation when the detected temperature of the exhaust purification catalyst is equal to or lower than a predetermined temperature. The gist of the invention is to drive the exhaust gas recirculation valve so that the forcible driving process is prohibited and the exhaust gas recirculation valve has an opening degree set based on the engine operating state.

According to the above configuration, it is possible to suppress an excessive temperature decrease of the exhaust purification catalyst due to the execution of the forced driving process of the exhaust gas recirculation valve.
A tenth aspect of the present invention is the abnormality diagnosis apparatus for the exhaust gas recirculation apparatus according to any one of the seventh to ninth aspects, wherein the valve driving means is a target opening degree when the exhaust gas recirculation valve is driven to be closed. The gist of the present invention is to set the lower limit opening so as to increase as the detected temperature of the exhaust purification catalyst decreases.

  According to the above configuration, when the exhaust gas recirculation valve is driven to close to the lower limit opening that is the target opening, the lower opening is set to be larger as the temperature of the exhaust purification catalyst is lower. Therefore, the lower the temperature of the exhaust purification catalyst, the more exhaust gas is allowed to flow into the catalyst, so that the temperature decrease of the catalyst can be appropriately suppressed.

  An eleventh aspect of the present invention is the exhaust gas recirculation apparatus abnormality diagnosis device according to any one of the first to tenth aspects, wherein the valve driving means has a predetermined opening degree of the exhaust gas recirculation valve during the forced driving process. The exhaust recirculation valve is driven to close until the opening becomes, and the detected amount of change in the exhaust gas recirculation amount is monitored, and the opening of the exhaust gas recirculation valve is delayed until the amount of change in the exhaust gas recirculation amount stabilizes. On the other hand, when the amount of change in the exhaust gas recirculation amount is not stable even after a predetermined period of time has elapsed, the forced drive processing is interrupted and the opening of the exhaust gas recirculation valve becomes an opening set based on the engine operating state The main point is to drive the exhaust gas recirculation valve.

  According to the above configuration, since the exhaust recirculation valve opening drive is delayed until the exhaust gas recirculation amount is stabilized after the exhaust recirculation valve closing drive is completed, the exhaust recirculation amount associated with the open drive is stabilized. Abnormalities can be diagnosed under the circumstances, and the diagnostic accuracy can be improved. Also, if the exhaust gas recirculation amount is not stable after a predetermined period of time, the forced drive process is interrupted and the exhaust gas recirculation valve is driven so that the opening of the exhaust gas recirculation valve becomes an opening based on the engine operating state. Therefore, it is possible to suppress the temperature of the exhaust purification catalyst from being lowered because the opening degree of the exhaust gas recirculation valve remains small for a long period of time.

  According to a twelfth aspect of the present invention, an exhaust gas recirculation passage that connects an exhaust system and an intake system of an in-vehicle internal combustion engine is provided in the exhaust gas recirculation passage, and an exhaust gas recirculation amount that is returned from the exhaust system to the intake system is adjusted. An exhaust gas recirculation apparatus having an exhaust gas recirculation valve that forcibly diagnoses the presence or absence of an abnormality in the exhaust gas recirculation apparatus abnormality diagnosis device is forced to drive the exhaust gas recirculation valve to be closed when an abnormality diagnosis execution condition is satisfied A valve driving means for executing a driving process; a change amount detecting means for detecting a change amount of the exhaust gas recirculation amount accompanying the driving of the exhaust gas recirculation valve during the forced driving process; and a closed drive of the exhaust gas recirculation valve in the forced driving process A diagnostic means for diagnosing that there is no abnormality when the amount of change in the exhaust gas recirculation amount associated with is greater than or equal to a predetermined determination value. That opening of the exhaust gas recirculation valve to interrupt the forced driving process for driving the exhaust gas recirculation valve so that the opening degree based on the engine operating state as its gist.

  In the above configuration, the exhaust gas recirculation valve is driven to close, and when the amount of change in the exhaust gas recirculation amount due to the closed driving is equal to or greater than a predetermined determination value, a diagnosis is made that there is no abnormality and a diagnosis is made that there is no abnormality. Sometimes, the forced drive process is interrupted, and the exhaust gas recirculation valve is driven so that the opening degree of the exhaust gas recirculation valve becomes an opening degree set based on the engine operating state. For this reason, it is possible to complete the abnormality diagnosis when the opening degree of the exhaust gas recirculation valve is small as compared with the case where the abnormality diagnosis of the exhaust gas recirculation device is executed simply by opening from the opening degree based on the engine operating state. Become. Further, when the abnormality diagnosis of the exhaust gas recirculation device is completed in this way, the opening degree of the exhaust gas recirculation valve is promptly changed to an opening degree set based on the engine operating state. Therefore, the exhaust gas recirculation valve is not opened more than necessary when the abnormality diagnosis is performed, and excessive exhaust gas recirculation is suppressed. Therefore, the abnormality diagnosis can be executed without causing an excessive temperature rise of the exhaust purification catalyst or instability of combustion.

  A thirteenth aspect of the present invention is the exhaust gas recirculation apparatus abnormality diagnosis device according to any one of the first to twelfth aspects, wherein the change amount detecting means includes an intake pressure sensor that detects an intake pressure. The amount of change in the exhaust gas recirculation amount is estimated based on the detection value of the atmospheric pressure sensor, and the diagnostic means changes this so that the determination value decreases as the detection value of the intake pressure sensor decreases, and after the change The gist is to execute an abnormality diagnosis based on the determination value.

  Further, the accuracy of the intake pressure sensor varies depending on the intake pressure, and the accuracy decreases as the intake pressure decreases. Therefore, when the amount of change in the exhaust gas recirculation amount is estimated based on the detection value of the intake pressure sensor, a decrease in the accuracy of the intake pressure sensor affects the estimation.

  In this regard, according to the structure described in claim 13, the abnormality diagnosis is executed using the determination value that is changed so as to decrease as the detection value of the intake pressure sensor decreases. Therefore, when there is a concern about a decrease in accuracy of the intake pressure sensor, that is, there is a deviation between the change amount of the exhaust gas recirculation amount and its true value, and the change amount is smaller than the true value. Even if it is assumed, it can be avoided that a misdiagnosis indicating an abnormality is made due to the decrease in accuracy.

  According to a fourteenth aspect of the present invention, in the abnormality diagnosis device for the exhaust gas recirculation apparatus according to any one of the first to thirteenth aspects, the change amount detecting means includes an intake pressure sensor that detects an intake pressure. The amount of change in the exhaust gas recirculation amount is estimated based on the detection value of the atmospheric pressure sensor, and the valve driving means performs the forced driving process of the exhaust gas recirculation valve when the detection value of the intake pressure sensor is less than a predetermined pressure. The gist is to drive the exhaust gas recirculation valve so that the opening degree is prohibited and the opening degree is set based on the engine operating state.

  According to the above configuration, when the detected value of the intake pressure sensor is less than the predetermined pressure, the accuracy of the sensor is low and abnormality diagnosis cannot be performed with the predetermined accuracy. Abnormal diagnosis is not executed. Therefore, it is possible to avoid making a wrong diagnosis due to a decrease in accuracy of the intake pressure sensor.

  According to a fifteenth aspect of the present invention, in the exhaust gas recirculation apparatus abnormality diagnosis device according to any one of the first to twelfth aspects, the intake pressure is adjusted so as to become a predetermined pressure value during the forced drive processing. The change amount detection means includes an intake pressure sensor for detecting intake pressure, and estimates the change amount of the exhaust gas recirculation amount based on a detection value of the intake pressure sensor. The gist of the present invention is that an abnormality diagnosis of the exhaust gas recirculation device is executed under the intake pressure of the intake system adjusted to a predetermined pressure value by the adjusting means.

  Also, the lower the intake pressure in the intake system, the greater the amount of change in the exhaust gas recirculation amount, so the detectability of abnormality diagnosis is improved. On the other hand, as described above, the lower the intake pressure of the intake system, there is a concern that the accuracy of the intake pressure sensor will decrease. For this reason, abnormality diagnosis is performed under the condition that the intake pressure of the intake system is low enough to improve the detectability of abnormality diagnosis and high enough that there is no concern about deterioration of the accuracy of the intake pressure sensor. It is desirable to execute.

  In this regard, in the configuration of the fifteenth aspect, the intake pressure of the intake system is adjusted to a predetermined pressure value by the adjusting means, and the abnormality diagnosis is executed under the adjusted intake pressure. For this reason, the abnormality diagnosis can be executed under conditions where an improvement in the detectability of the abnormality diagnosis can be expected and a decrease in the accuracy of the intake pressure sensor is not a concern.

  Specifically, as in the configuration described in claim 16, the adjustment means includes a throttle valve that regulates the intake air amount, and in the configuration according to claim 17, the adjustment means exceeds the intake air. It is possible to adopt a configuration including a supercharging pressure variable supercharger for supplying.

  The invention according to claim 18 is the exhaust gas recirculation apparatus abnormality diagnosis device according to any one of claims 1 to 17, wherein the valve drive means has a slow change in the exhaust gas recirculation amount during the forced drive processing. The gist is to gradually change the opening of the exhaust gas recirculation valve so as to become.

  According to the above configuration, since the opening degree of the exhaust gas recirculation valve is gradually changed so as to slow down the change in the exhaust gas recirculation amount, the intake system pressure is rapidly increased with the change in the exhaust gas recirculation valve opening degree. It can suppress that a change arises. Accordingly, it is possible to avoid an increase in operating sound such as a seating sound of the exhaust gas recirculation valve and a deterioration in drivability.

  The invention according to claim 19 is the abnormality diagnosis device for the exhaust gas recirculation apparatus according to any one of claims 1 to 18, wherein the abnormality diagnosis indicates that the vehicle is decelerating and fuel cut is being executed. The gist is to include it as an execution condition.

  According to the above configuration, the abnormality diagnosis is executed when the vehicle is decelerating and the fuel cut is being executed. Therefore, the abnormality diagnosis can be executed under a situation where the influence on the engine operation is small.

The schematic diagram which shows the structure of the diesel engine used as the application object about 1st Embodiment of this invention. The flowchart which shows the process sequence of the abnormality diagnosis control concerning the embodiment. 7 is a flowchart showing a processing procedure of abnormality diagnosis processing according to the embodiment. The conceptual diagram which shows the relationship between an EGR flow volume and intake pressure. The timing chart which shows transition of the EGR valve opening degree and EGR flow volume in case the abnormality diagnosis process concerning the embodiment is performed. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 2nd Embodiment of this invention. The timing chart which shows transition of the EGR valve opening degree and EGR flow volume in case the abnormality diagnosis process concerning the embodiment is performed. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 3rd Embodiment of this invention. In the abnormality diagnosis processing according to the embodiment, the EGR valve opening degree and EGR when it is diagnosed that there is no abnormality in the EGR device when the vehicle is traveling in a lowland and when traveling in a highland The timing chart which shows transition of flow volume. In the abnormality diagnosis processing according to the embodiment, the EGR valve opening degree and EGR when it is diagnosed that an abnormality has occurred in the EGR device when the vehicle is traveling in a lowland and when traveling in a highland The timing chart which shows transition of flow volume. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 4th Embodiment of this invention. The conceptual diagram which shows the relationship between the opening degree holding | maintenance period and determination value in the same embodiment, and catalyst bed temperature. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 5th Embodiment of this invention. The conceptual diagram which shows the relationship between the lower limit opening degree and catalyst bed temperature in the same embodiment. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 6th Embodiment of this invention. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 7th Embodiment of this invention. The conceptual diagram which shows the relationship between the determination value in the same embodiment, the intake pressure sensor precision, and intake pressure. The flowchart which shows a part of the process sequence about the abnormality diagnosis process concerning 8th Embodiment of this invention. The conceptual diagram which shows the relationship between the detectability of the abnormality diagnosis in the same embodiment, the intake pressure sensor precision, and intake pressure.

(First embodiment)
Hereinafter, a first embodiment of an abnormality diagnosis device for an exhaust gas recirculation device according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing a diesel engine (hereinafter simply referred to as “engine”) as an in-vehicle internal combustion engine to which an abnormality diagnosis device for an exhaust gas recirculation apparatus according to the present embodiment is applied, and a peripheral configuration thereof.

  The engine 1 is provided with a plurality of cylinders # 1 to # 4, and the cylinder head 2 is provided with a plurality of fuel injection valves 4a to 4d. These fuel injection valves 4a to 4d inject fuel into the combustion chambers of the respective cylinders # 1 to # 4. The cylinder head 2 is provided with intake ports for introducing air into the combustion chamber and exhaust ports 6a to 6d for discharging exhaust gas from the combustion chamber corresponding to the cylinders # 1 to # 4. Yes.

  The fuel injection valves 4a to 4d are connected to a common rail 9 that accumulates high-pressure fuel, and fuel in the fuel tank pressurized by the supply pump 10 is supplied to the common rail 9 as high-pressure fuel.

  An intake manifold 7 is connected to the intake port. A throttle valve 16 for adjusting the intake air amount and the intake pressure is provided in the intake passage 3 connected to the intake manifold 7. On the other hand, an exhaust manifold 8 is connected to the exhaust ports 6 a to 6 d, and an exhaust passage 28 is connected to the exhaust manifold 8.

  In the middle of the exhaust passage 28, there is provided a supercharger 11 of a variable supercharging pressure type that supercharges intake air introduced into the combustion chamber using exhaust pressure. In the supercharger 11, a plurality of nozzle valves for changing the exhaust flow velocity when blowing exhaust gas to the turbine wheel are provided around the turbine wheel, and supercharging is performed by changing the opening of the nozzle valve. The target supercharging pressure of the machine 11 can be changed. An intercooler 18 is provided in the intake passage 3 between the intake side compressor wheel of the supercharger 11 and the throttle valve 16. The intercooler 18 cools the intake air whose temperature has increased due to the supercharging of the supercharger 11.

  An exhaust purification catalyst 30 that purifies exhaust components is provided in the middle of the exhaust passage 28 and downstream of the exhaust side turbine of the supercharger 11. Inside the exhaust purification catalyst 30, an oxidation catalyst 31 and a filter 32 are sequentially arranged in the exhaust flow direction.

  The oxidation catalyst 31 carries a catalyst for oxidizing HC in the exhaust. The filter 32 is a member that collects PM (particulate matter) in the exhaust gas and is composed of a porous ceramic structure. When the PM in the exhaust gas passes through the porous wall, It is collected.

  The cylinder head 2 is provided with a fuel addition valve 5 for supplying fuel as an additive to the oxidation catalyst 31 and the filter 32. The fuel addition valve 5 is connected to the supply pump 10 via a fuel supply pipe 27, and fuel is injected from the fuel addition valve 5 into the exhaust port 6d of the fourth cylinder # 4. The injected fuel is supplied to the oxidation catalyst 31 and the filter 32 together with the exhaust gas.

  In addition, the engine 1 is provided with an exhaust gas recirculation device 22 (hereinafter referred to as an EGR device). The EGR device 22 is provided in an exhaust gas recirculation passage 23 (hereinafter referred to as an EGR passage) that connects an intake passage 3 that is an intake system of the engine 1 and an exhaust manifold 8 that is an exhaust system, and the EGR passage 23. An exhaust gas recirculation valve 25 (hereinafter referred to as an EGR valve) for adjusting the recirculation amount of the exhaust gas returned from the exhaust passage 28 to the intake passage 3 is provided. By changing the opening degree of the EGR valve 25, the recirculation amount of the exhaust gas returned to the intake passage 3 is adjusted. Further, in the EGR passage 23, an EGR cooler 24 for cooling the exhaust is provided on the exhaust upstream side of the EGR valve 25, and the exhaust gas flowing in the EGR passage 23 is cooled by the EGR cooler 24.

  The engine 1 is provided with various sensors for detecting the engine operating state. For example, an air flow meter 19 that detects the amount of intake air in the intake passage 3 and an intake pressure sensor 21 that detects the intake pressure PIM in the intake passage 3 are provided. Further, an opening sensor 26 for detecting the opening of the EGR valve 25 and a throttle opening sensor 20 for detecting the opening of the throttle valve 16 are provided. The exhaust purification catalyst 30 is provided with a temperature sensor 33 that directly detects the catalyst bed temperature T, which is the temperature of the catalyst. Then, an atmospheric pressure sensor 41 that detects an atmospheric pressure Patm outside the vehicle as a traveling environment of the vehicle, an outside air temperature sensor 42 that also detects an outside air temperature as a traveling environment of the vehicle, and a traveling speed of the vehicle as an operating state of the engine 1. A vehicle speed sensor 43 that detects a certain vehicle speed SP is provided.

  In addition, the engine 1 includes an engine rotation speed sensor that detects the rotation speed of the crankshaft, that is, the engine rotation speed NE, an accelerator sensor that detects the depression amount of the accelerator pedal, that is, the accelerator operation amount ACCP, and an engine that is the engine water temperature. A water temperature sensor or the like for detecting the water temperature THW is provided.

  Outputs of these various sensors are input to the control device 40. The control device 40 is mainly composed of a central processing control device (CPU), a read-only memory (ROM) that stores various programs and maps in advance, and a random access memory (RAM) that temporarily stores calculation results of the CPU. ing.

  The control device 40 controls the fuel injection amount control / fuel injection timing control of the fuel injection valves 4 a to 4 d and the fuel addition valve 5, the discharge pressure control of the supply pump 10, and the drive amount of the actuator 17 that opens and closes the throttle valve 16. Various controls of the engine 1 such as control and filter regeneration control for burning the PM collected by the filter 32 are performed. The opening degree control of the EGR valve 25 and the like are also performed by the control device 40. In the opening degree control of the EGR valve 25, the recirculation amount of the exhaust gas is controlled by changing the opening degree of the EGR valve 25 based on the engine operating state estimated from the engine rotational speed NE, the accelerator operation amount ACCP, and the like. The amount is controlled so as to suit the condition.

  By the way, in the EGR device as in the present embodiment, abnormalities such as malfunction of the EGR valve and blockage of the EGR passage may occur, and in this case, the exhaust gas recirculation amount (EGR flow rate) matches the engine operating state. It becomes difficult to control to an appropriate amount.

  Therefore, in order to diagnose the presence or absence of such an abnormality, for example, it is conceivable to perform an abnormality diagnosis as follows. That is, when the engine is idling, the EGR valve is forcibly opened, and the amount of change in the EGR flow rate that accompanies this opening is calculated, and it is determined that the amount of change is equal to or less than a determination value. When it is done, it is diagnosed that an abnormality has occurred in the EGR device.

  However, if the opening of the EGR valve is forcibly opened from the opening set in accordance with the engine operating state in this way, the intake air amount decreases by the amount of increase in the EGR flow rate, so that the recirculated exhaust gas is reduced. The temperature of the intake air including it will rise. For this reason, the temperature of the exhaust gas flowing into the exhaust purification catalyst provided in the exhaust system also increases, and the exhaust purification catalyst may excessively increase in temperature. Incidentally, such an increase in the temperature of the exhaust purification catalyst can occur not only during engine combustion but also when abnormality diagnosis is performed when engine combustion is stopped during fuel cut. That is, the intake air flowing into the combustion chamber is discharged as exhaust gas after the temperature rises due to compression by the piston during the compression stroke and heat exchange with the combustion chamber wall and the piston top surface, but this is recirculated to the intake passage 3 and again When the temperature rises, the temperature becomes extremely high. For this reason, even when the engine combustion is stopped, the temperature of the exhaust purification catalyst may excessively rise when the EGR flow rate increases.

  In addition, when there is an acceleration request while the EGR valve is forced to open, the engine load increases, the EGR valve is driven to close and the intake amount is increased, but this has a response delay, There is a risk that combustion becomes unstable due to a shortage of intake air, drivability may deteriorate, and smoke may be generated. In particular, such inconvenience is likely to occur in an environment where the density of intake air is low, such as at high altitudes.

  Therefore, in the control device 40 of the present embodiment, the abnormality diagnosis control of the EGR device 22 is executed so as to execute the abnormality diagnosis without causing an excessive temperature rise of the exhaust purification catalyst 30 or instability of combustion. Yes. Hereinafter, this abnormality diagnosis control will be described with reference to FIGS.

  FIG. 2 shows a processing procedure of abnormality diagnosis control employed in the present embodiment. This process is repeatedly executed during engine operation by the control device 40 corresponding to the abnormality diagnosis device.

  When the process of this control is started, it is first determined whether or not the vehicle is decelerating (step S110). Here, it is determined that the vehicle is decelerating when the accelerator operation amount ACCP is “0” and the vehicle speed SP is equal to or higher than a predetermined speed. If it is determined that the vehicle is decelerating (step S110: YES), it is then determined whether or not a fuel cut is being performed (step S120). If it is determined that the fuel is being cut (step S120: YES), the process proceeds to the next step. Thus, since the engine combustion is stopped when the vehicle is decelerating and the fuel cut is in progress, even if the abnormality diagnosis control accompanied by the change in the opening degree of the EGR valve 25 is executed, the execution is not performed in the engine. The effect on driving is extremely small. Therefore, the execution condition of the abnormality diagnosis control is that the vehicle is decelerating and fuel cut. On the other hand, if it is determined that the vehicle is not decelerating (step S110: NO), or if it is determined that the vehicle is not being fuel cut (step S120: NO), the condition for executing the abnormality diagnosis control is not satisfied, and the above-described condition is not satisfied. As described above, the influence of the execution of the abnormality diagnosis control on the engine operation cannot be ignored, and this process is temporarily terminated.

  Subsequently, the abnormality diagnosis process is started (step S130). The abnormality diagnosis process is continuously executed after the start of the abnormality diagnosis until the fuel injection is not resumed (step S140: NO). On the other hand, when the fuel injection is resumed (step S140: YES), the abnormality diagnosis process is stopped (step S150), and this process is temporarily terminated.

  Next, the processing procedure of the abnormality diagnosis process (FIG. 2: S130) will be described with reference to the flowchart shown in FIG. In this process, a forced drive process is executed in which the EGR valve 25 is once closed and then opened. That is, when this process is started, first, the EGR valve 25 is started to be closed (step S210). The EGR valve 25 is continuously closed until the EGR valve 25 is closed to the lower limit opening degree Aegrd (step S220: NO). In addition, the lower limit opening degree Aegrd in the present embodiment is set in advance to a fully closed opening degree (minimum opening degree). Similarly, the lower limit opening degree Aegrd in other embodiments to be described later is also set in advance to the fully closed opening degree.

  When it is determined that the EGR valve 25 is closed to the lower limit opening degree Aegrd (step S220: YES), the opening degree of the EGR valve 25 is maintained for the opening degree holding period Tc while keeping the lower limit opening degree Aegrd. (Step S230), the opening driving of the EGR valve 25 is started (Step S240).

  Here, when the EGR valve 25 is once closed and then opened immediately, the change in the EGR flow rate due to the drive of the EGR valve 25 has a response delay. The EGR valve 25 may be driven to open before being reduced to an amount corresponding to the opening degree. Therefore, in this embodiment, in consideration of such a response delay period of the EGR flow rate, the opening degree is held until a predetermined opening degree holding period Tc elapses after the EGR valve 25 is closed. ing. The opening holding period Tc is a period in which the response delay of the EGR flow rate described above is eliminated, and is set in advance.

  Then, it is determined whether or not the EGR valve 25 has been opened to the upper limit opening degree Aegru (step S250). In addition, the upper limit opening degree Aegru in the present embodiment is set in advance to a fully open opening degree (maximum opening degree). In addition, the upper limit opening degree Aegru in other embodiments to be described later is also set in advance to the fully open degree.

  If it is determined that the EGR valve 25 has not been opened to the upper limit opening degree Aegru (step S250: NO), the change amount ΔFegr (absolute value) of the EGR flow rate since the opening of the EGR valve 25 is started. Is determined to be greater than or equal to a determination value ΔFegrp (step S260).

  Here, the change amount ΔFegr of the EGR flow rate is estimated based on the intake pressure PIM in the intake passage 3 detected from the intake pressure sensor 21. Specifically, the change amount ΔFegr of the EGR flow rate is estimated with reference to the map shown in FIG. The map shown in FIG. 4 shows the relationship between the intake pressure PIM and the EGR flow rate when the EGR valve 25 is changed between the fully closed state and the fully open state. In this map, the EGR flow rate is set to increase as the intake pressure PIM increases. In the map of FIG. 4, the relationship between the intake pressure PIM and the EGR flow rate shown is determined in advance, and this map is stored in advance in the memory of the control device 40.

  Further, the determination value ΔFegrp is a change amount of the EGR flow rate detected when the EGR device 22 has no abnormality, and is a change amount of the EGR flow rate detected by an experiment or the like. is there.

  If the estimated change amount ΔFegr of the EGR flow is less than the determination value ΔFegrp (step S260: NO), if the EGR valve 25 is not opened to the upper limit opening Aegru, the change amount ΔFegr of the EGR flow rate is determined. It is continuously determined whether or not the value ΔFegrp is exceeded.

  When it is determined that the change amount ΔFegr of the EGR flow rate is equal to or greater than the determination value ΔFegrp (step S260: YES), it is diagnosed that no abnormality has occurred in the EGR device 22 (step S290).

  On the other hand, if it is determined that the EGR valve 25 has been opened to the upper limit opening Aegru before the change amount ΔFegr of the EGR flow rate becomes equal to or larger than the determination value ΔFegrp (step S250: YES), the opening degree of the EGR valve 25 is increased to the upper limit. The opening degree Aegru is maintained (step S265). In this manner, it is determined whether or not the change amount ΔFegr of the EGR flow rate is equal to or larger than the determination value ΔFegrp while maintaining the opening degree of the EGR valve 25 (step S270). The determination value ΔFegrp here is the same value as the determination value ΔFegrp in step S260.

  If it is determined that the change amount ΔFegr of the EGR flow rate is less than the determination value ΔFegrp (step S270: NO), has the predetermined time Td elapsed since the opening of the EGR valve 25 was maintained at the upper limit opening Aegru? It is determined whether or not (step S280). Here, the predetermined time Td is a period during which the response delay of the EGR flow rate is eliminated, as in the opening degree holding period Tc described above, and is set in advance.

  Then, while the opening degree of the EGR valve 25 is maintained at the upper limit opening degree Aegru, while the predetermined time Td has not elapsed (step S280: NO), whether or not the change amount ΔFegr of the EGR flow rate is equal to or larger than the determination value ΔFegrp. Judgment continues.

  If it is determined that the change amount ΔFegr of the EGR flow rate is equal to or greater than the determination value ΔFegrp (step S270: YES), it is diagnosed that no abnormality has occurred in the EGR device 22 (step S290).

  Thus, when the EGR valve 25 is opened to the upper limit opening Aegru and the EGR flow rate change amount ΔFegr is equal to or larger than the determination value ΔFegrp during the period in which the upper limit opening Aegru is maintained for the predetermined time Td (step S260, step S270: YES), it is diagnosed that there is no abnormality in the EGR device 22, and the forced drive processing of the EGR valve 25 is interrupted.

  On the other hand, if it is determined that the predetermined time Td has elapsed since the opening of the EGR valve 25 is maintained at the upper limit opening Aegru (step S280: YES), it is diagnosed that an abnormality has occurred in the EGR device 22 ( Step S295).

  Thus, when the EGR valve 25 is opened to the upper limit opening Aegru while the change amount ΔFegr of the EGR flow rate does not become the determination value ΔFegrp or more, and when the predetermined time Td has elapsed since the opening degree is maintained at the upper limit opening Aegru. The EGR device 22 is diagnosed as having an abnormality.

  After the diagnosis that no abnormality has occurred in the EGR device 22 (step S290) or the diagnosis that the abnormality has occurred in the EGR device 22 (step S295), the opening degree of the EGR valve 25 is determined based on the engine operating state. Is set to an opening based on (step S300). Specifically, the opening degree of the EGR valve 25 is changed based on the engine operating state by the opening degree control of the EGR valve 25 described above. And this process is once complete | finished.

Next, state transition when the abnormality diagnosis control of the present embodiment is executed will be described with reference to FIG.
When the condition for executing the abnormality diagnosis is satisfied, as shown in FIG. 5, the abnormality diagnosis process is started, and the EGR valve 25 is started to be closed (timing t1). When the EGR valve 25 is closed to the lower limit opening degree Aegrd (fully closed) (timing t2), the opening degree of the EGR valve is maintained for the opening degree holding period Tc while keeping the lower limit opening degree Aegrd. Here, when it is diagnosed that there is no abnormality in the EGR device 22, as shown by a solid line in FIG. 5, the response delay of the EGR flow rate is eliminated during the opening holding period Tc, and the EGR flow rate is also reduced. The amount corresponds to the lower limit opening degree Aegrd (“0” in the figure).

  Then, when the same opening degree holding period Tc elapses, the EGR valve 25 is started to open toward the upper limit opening degree Aegru (fully open) (timing t3). As the EGR valve 25 is opened, the EGR flow rate change amount ΔFegr increases. Here, as shown in FIG. 5, when the EGR flow rate change ΔFegr is equal to or greater than the determination value ΔFegrp before the EGR valve 25 is opened to the upper limit opening degree Aegru, no abnormality has occurred in the EGR device 22. (Timing t4), the forced drive process for forcibly opening the EGR valve 25 is interrupted. Then, the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state.

  On the other hand, when it is diagnosed that an abnormality has occurred in the EGR device 22, after the EGR valve 25 is maintained for the opening degree holding period Tc with the lower limit opening degree Aegrd as shown by a one-dot chain line in FIG. Even when the opening driving of the EGR valve 25 is started toward the upper limit opening degree Aegru, the change amount ΔFegr of the EGR flow rate does not become the determination value ΔFegrp or more. Then, the EGR valve 25 is opened to the upper limit opening Aegru without changing the EGR flow rate change amount ΔFegr to the determination value ΔFegrp (timing t5), and when the upper limit opening Aegru is maintained at the predetermined time Td (timing). At t6), it is diagnosed that an abnormality has occurred in the EGR device 22, and the forced driving process is interrupted. Then, the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state.

  In addition, although not shown, the EGR valve 25 is opened to the upper limit opening Aegru and maintained at the upper limit opening Aegru for a predetermined time Td (corresponding to timing t5 to timing t6). Even when the change amount ΔFegr of the above becomes equal to or larger than the determination value ΔFegrp, it is diagnosed that no abnormality has occurred in the EGR device 22. And the said forced drive process is interrupted and the opening degree of the EGR valve 25 is set to the opening degree based on an engine operating state.

  In the present embodiment, the EGR valve 25 is closed until the opening degree reaches the lower limit opening degree Aegrd (timing t1 to timing t2) or the opening period until the EGR valve 25 reaches the upper limit opening degree Aegru (timing t3 to t4). When the EGR valve 25 is driven, the opening degree of the EGR valve 25 is gradually changed so that the change in the EGR flow rate becomes slow. By changing the opening degree of the EGR valve 25 in this way, it is possible to suppress a sudden change in the pressure of the intake system such as the intake passage 3 or the like. Note that the manner of changing the opening degree of the EGR valve 25 in which the opening degree of the EGR valve 25 is gradually changed in this way is the same in other embodiments described later.

According to the embodiment described above, the following effects can be obtained.
(1) The EGR valve 25 is once closed and then opened, and when the change amount ΔFegr in the EGR flow resulting from the opening is equal to or greater than a predetermined determination value ΔFegrp, it is diagnosed that there is no abnormality and there is no abnormality When the diagnosis is made, the forcible drive process is interrupted and the EGR valve 25 is driven so that the opening of the EGR valve 25 becomes an opening set based on the engine operating state. Therefore, the abnormality diagnosis is performed at a stage where the opening degree of the EGR valve 25 is relatively small as compared with the case where the abnormality diagnosis of the EGR device 22 is executed by simply opening the EGR valve 25 from the opening degree based on the engine operating state. It can be completed. Further, when the abnormality diagnosis of the EGR device 22 is completed in this way, the opening degree of the EGR valve 25 is promptly changed to an opening degree set based on the engine operating state. Therefore, the EGR valve 25 is not opened more than necessary when the abnormality diagnosis is performed, and excessive exhaust gas recirculation is suppressed. Therefore, the abnormality diagnosis can be executed without causing an excessive temperature rise of the exhaust purification catalyst 30 or instability of combustion.

  (2) Since the opening degree of the EGR valve 25 is gradually changed so as to slow the change in the recirculation amount of the exhaust gas, a sudden change in the pressure of the intake system occurs with the change in the opening degree of the EGR valve 25. It is possible to suppress the occurrence. Accordingly, it is possible to avoid an increase in operating sound such as a seating sound of the EGR valve 25 and a deterioration in drivability.

(3) Since the abnormality diagnosis is executed when the vehicle is decelerating and the fuel cut is being executed, the abnormality diagnosis can be executed under a situation where the influence on the engine operation is small.
(Second Embodiment)
A second embodiment that embodies an abnormality diagnosis device for an exhaust gas recirculation device according to the present invention will be described below with reference to FIGS. 6 and 7. The present embodiment and the first embodiment are partially different from each other in the abnormality diagnosis process shown in FIG. Hereinafter, the present embodiment will be described focusing on such differences.

  Here, as described above, when the opening degree of the EGR valve 25 is increased at the time of abnormality diagnosis, the temperature of the intake air including the exhaust rises, so the temperature of the exhaust gas flowing into the exhaust purification catalyst 30 also rises and the exhaust purification catalyst 30 The temperature may rise excessively. On the other hand, if the opening degree of the EGR valve 25 is reduced, the exhaust gas recirculation amount decreases and the temperature of the exhaust gas flowing into the exhaust purification catalyst 30 decreases. is there. In particular, when the exhaust purification catalyst 30 before executing the abnormality diagnosis is extremely low, such as when the warm-up is completed or when the low load operation is continued for a long period of time, the exhaust purification catalyst 30 during the abnormality diagnosis is being executed. In some cases, the temperature drop cannot be ignored.

  Therefore, in the present embodiment, prior to the abnormality diagnosis at the time of opening drive, the abnormality diagnosis of the EGR device 22 is executed even when the EGR valve 25 is closed, and the opening degree of the EGR valve 25 is set to the lower limit opening degree Aegrd. If it is diagnosed that there is no abnormality before reaching the EGR valve 25, the EGR valve 25 is not further closed and the forced driving process of the EGR valve 25 is interrupted at that point to end the abnormality diagnosis.

  FIG. 6 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In this process, the abnormality diagnosis process is started when the above-described abnormality diagnosis execution condition is satisfied (FIG. 2: step S130). It should be noted that an abnormality diagnosis process in another embodiment to be described later is also executed when the abnormality diagnosis process is started in accordance with the establishment of such an abnormality diagnosis execution condition.

  First, as shown in FIG. 6, in the abnormality diagnosis process, the EGR valve 25 is started to be closed in the same manner as the process procedure shown in FIG. 3 (step S310). In the present embodiment, it is determined whether or not the EGR valve 25 is closed to the lower limit opening degree Aegrd (step S320).

  When it is determined that the EGR valve 25 has not been closed to the lower limit opening degree Aegrd (step S320: NO), the change amount ΔFegr of the EGR flow rate after the EGR valve 25 starts to be closed is determined as the determination value ΔFegrp. It is determined whether or not the above has been reached (step S325).

  Here, it is assumed that the change amount ΔFegr of the EGR flow rate is estimated based on the intake pressure PIM in the intake passage 3 detected from the intake pressure sensor 21 as in the first embodiment. Further, the determination value ΔFegrp of the present embodiment is the same as the determination value ΔFegrp of the first embodiment, and is detected when the EGR device 22 is not abnormal and is detected as the opening degree of the EGR valve 25 is changed. This is a value of the flow rate, and is a value set in advance by experiments or the like.

  If the estimated change amount ΔFegr of the EGR flow rate is less than the determination value ΔFegrp (step S325: NO), the EGR flow rate is maintained until the opening degree of the EGR valve 25 becomes the lower limit opening degree Aegrd. It is continuously determined whether or not the amount of change ΔFegr has become equal to or greater than the determination value ΔFegrp.

  When it is determined that the change amount ΔFegr of the EGR flow rate is equal to or greater than the determination value ΔFegrp (step S325: YES), it is diagnosed that no abnormality has occurred in the EGR device 22 as shown in FIG. FIG. 3: Step S290). Therefore, in this case, the forced driving process of the EGR valve 25 is interrupted, and the opening degree of the EGR valve 25 is not further reduced, so that the temperature reduction of the exhaust purification catalyst 30 is suppressed.

  If it is determined that the EGR valve 25 is closed to the lower limit opening degree Aegrd (step S320: YES), the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd (step S330). Then, it is determined whether or not the change amount ΔFegr of the EGR flow rate is equal to or larger than the determination value ΔFegrp (step S332). The determination value ΔFegrp here is the same value as the determination value ΔFegrp in step S325.

  When it is determined that the change amount ΔFegr of the EGR flow rate is less than the determination value ΔFegrp (step S332: NO), the opening holding period Tc has elapsed since the opening of the EGR valve 25 is maintained at the lower limit opening Aegrd. It is determined whether or not it has been done (step S334). Here, the opening degree holding period Tc is a period in which the response delay of the EGR flow rate is eliminated, similarly to the opening degree holding period Tc employed in step S230 of FIG. 3, and is set in advance.

  Then, while the opening degree holding period Tc does not elapse after the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd (step S334: NO), whether or not the change amount ΔFegr of the EGR flow amount is equal to or larger than the determination value ΔFegrp. This judgment is continued.

  If it is determined that the change amount ΔFegr of the EGR flow rate is equal to or greater than the determination value ΔFegrp (step S332: YES), it is diagnosed that no abnormality has occurred in the EGR device 22 as shown in FIG. 3 (FIG. 3). : Step S290). Therefore, in this case, the forced drive processing of the EGR valve 25 is interrupted, and the period during which the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd is shortened, so that the temperature reduction of the exhaust purification catalyst 30 is suppressed. become.

  Thus, while the EGR valve 25 is closed to the lower limit opening degree Aegrd and the forced drive processing that is maintained for the opening degree holding period Tc at the lower limit opening degree Aegrd is executed, the amount of change in the EGR flow rate When ΔFegr becomes equal to or larger than the determination value ΔFegrp (step S325, step S332: YES), it is diagnosed that there is no abnormality in the EGR device 22, the forced drive processing of the EGR valve 25 is interrupted, and the EGR valve 25 The opening is set to an opening based on the engine operating state. That is, in this case, the abnormality diagnosis is completed without opening the EGR valve 25.

  On the other hand, if it is determined that the opening degree holding period Tc has elapsed since the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd (step S334: YES), the process proceeds to step S240 in FIG. Then, opening driving of the EGR valve 25 is started. Then, as in the first embodiment, an abnormality diagnosis of the EGR device 22 is performed as the EGR valve 25 is driven to open. When the opening degree of the EGR valve 25 before executing the forcible driving process, that is, the opening degree of the EGR valve 25 set based on the engine operating state is small, the change amount ΔFegr of the EGR flow amount accompanying the closing driving of the EGR valve 25 is Get smaller. For this reason, even when there is no abnormality in the EGR device 22, there is a case where no abnormality is diagnosed in the abnormality diagnosis during the closed drive. However, in such a case, it can be diagnosed that there is no abnormality in the abnormality diagnosis performed when the EGR valve 25 is opened thereafter.

  In the present embodiment, the determination value ΔFegrp (step S325, step S332) used for the above-described abnormality diagnosis during the closed drive and the determination value ΔFegrp (step S260, step S270) used for the abnormality diagnosis during the open drive described above. Are set to the same value.

  Next, state transition when the abnormality diagnosis control of the present embodiment is executed will be described with reference to FIG. In FIG. 7, a case will be described in which an abnormality diagnosis execution condition is established such that the vehicle is decelerating and the fuel is being cut.

  When the execution condition is satisfied, as shown in FIG. 7, an abnormality diagnosis process is started, and the EGR valve 25 is started to be closed (timing t1). If no abnormality occurs in the EGR device 22, the EGR flow rate decreases as the EGR valve 25 is closed toward the lower limit opening Aegrd (fully closed) as shown by the solid line in FIG. To do. Here, as shown in FIG. 7, if the EGR flow rate change ΔFegr is equal to or greater than the determination value ΔFegrp before the EGR valve 25 is closed to the lower limit opening degree Aegrd, no abnormality has occurred in the EGR device 22. (Timing t7), the forcible drive process for forcibly closing the EGR valve 25 is interrupted. Then, the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state (timing t8).

  When the opening degree of the EGR valve 25 before the forced driving process is executed, that is, when the opening degree of the EGR valve 25 set based on the engine operating state is small, as indicated by a one-dot chain line in FIG. Furthermore, the change amount ΔFegr of the EGR flow rate accompanying the closing drive of the EGR valve 25 becomes small. For this reason, even when no abnormality has occurred in the EGR device 22, there is a case where no abnormality is diagnosed in the abnormality diagnosis during the closed drive.

However, in such a case, it can be diagnosed that there is no abnormality in the abnormality diagnosis when the EGR valve 25 is opened, which is executed after the EGR valve 25 is driven to close.
In addition, although not shown, while the EGR valve 25 is closed to the lower limit opening degree Aegrd and the opening degree holding period Tc is maintained while the lower limit opening degree Aegrd is maintained, the change amount ΔFegr of the EGR flow rate is a determination value. Even when ΔFegrp is exceeded, it is diagnosed that there is no abnormality in the EGR device 22. And the said forced drive process is interrupted and the opening degree of the EGR valve 25 is set to the opening degree based on an engine operating state.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(4) According to the present embodiment, prior to the abnormality diagnosis at the time of open driving, the abnormality diagnosis of the EGR device 22 is executed even when the EGR valve 25 is driven to close. If the EGR device 22 is diagnosed as having no abnormality during the abnormality diagnosis during the closed drive, the opening of the EGR valve 25 is stopped without interrupting the forced drive process and further driving the EGR valve 25 to be closed. Is quickly changed to the opening degree set based on the engine operating state. For this reason, the time required for abnormality diagnosis can be shortened, and the temperature reduction of the exhaust purification catalyst 30 can be suppressed.

(Third embodiment)
A third embodiment of the exhaust gas recirculation device abnormality diagnosis device according to the present invention will be described below with reference to FIGS. The present embodiment and the first embodiment are partially different from each other in the abnormality diagnosis process shown in FIG. In the following, this embodiment will be described focusing on such differences.

  Here, for example, when an abnormality diagnosis is performed with the fuel cut during deceleration as an execution condition, the abnormality diagnosis is interrupted when the fuel cut is stopped due to an acceleration request. Therefore, the EGR valve 25 is based on the engine operating state. It is controlled so that the opening is set. Here, since there is a response delay from when the abnormality diagnosis is interrupted until the EGR flow rate becomes an amount suitable for the engine operating state, the opening degree of the EGR valve 25 is, for example, due to the forced driving of the EGR valve 25 at the time of abnormality diagnosis. For example, when the opening is fully open, exhaust exceeding the amount suitable for the engine operating state may return to the intake system during the response delay period. In particular, in an environment such as high altitudes where atmospheric pressure is low and air density is low, the amount of intake air that is introduced into the cylinder is smaller than that on flat ground. May occur.

  Therefore, in the present embodiment, the lower the atmospheric pressure as the running environment of the vehicle, the smaller the upper limit opening degree Aegru and the determination value ΔFegrp for the EGR flow rate change ΔFegr when the EGR valve 25 is opened. These are set to be variably set.

  FIG. 8 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In the present embodiment, when the abnormality diagnosis process is started, first, the upper limit opening degree Aegru and the determination value ΔFegrp are set according to the atmospheric pressure Patm detected from the atmospheric pressure sensor 41 (step S405).

That is, as the atmospheric pressure Patm is lower, the upper limit opening Aegru and the determination value ΔFegrp are set to be smaller, assuming that the vehicle is traveling on a highland.
After the upper limit opening Aegru and the determination value ΔFegrp are set in this way, the process proceeds to step S210 shown in FIG. 3 and the EGR valve 25 is started to be closed. In the present embodiment, as in the first embodiment, abnormality diagnosis of the EGR device 22 is performed only when the EGR valve 25 is opened. Then, the EGR valve 25 is driven to open toward the upper limit opening Aegru set as described above, and an abnormality diagnosis of the EGR device 22 is performed with the determination value ΔFegrp.

  Next, state transition when the abnormality diagnosis control of the present embodiment is executed will be described with reference to FIGS. 9 and 10. 9 and 10, a case will be described in which an abnormality diagnosis execution condition is established such that the vehicle is decelerating and the fuel cut is in progress. 9 shows a case where it is diagnosed that there is no abnormality in the EGR device 22, and FIG. 10 shows a case where it is diagnosed that there is an abnormality in the EGR device 22.

  First, a description will be given with reference to FIG. When the execution condition is satisfied, similarly to the first embodiment, after the abnormality diagnosis process is started (timing t1), the EGR valve 25 is closed to the lower limit opening degree Aegrd (fully closed) (timing t2). The opening degree of the EGR valve 25 is maintained during the opening degree holding period Tc with the same lower limit opening degree Aegrd (timing t2 to timing t3).

  Then, opening driving of the EGR valve 25 is started (timing t3). Here, when the vehicle is traveling on a highland, a relatively low value is detected as the atmospheric pressure Patm, so the determination value ΔFegrp is set to a small value. Therefore, when the vehicle is traveling on a highland (shown by a solid line in FIG. 9), the EGR valve 25 is compared to when the vehicle is traveling on a lowland (illustrated by a one-dot chain line in FIG. 9). A change amount ΔFegr of the EGR flow rate that is equal to or greater than the determination value ΔFegrp is detected while the opening degree is relatively small (timing t9). Thus, when it is determined that the change amount ΔFegr of the EGR flow rate is equal to or larger than the determination value ΔFegrp, it is diagnosed that there is no abnormality in the EGR device 22, and the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state. The

  Next, a description will be given with reference to FIG. When the execution condition is satisfied, the EGR valve 25 is driven to close as in the case shown in FIG. Then, opening driving of the EGR valve 25 is started.

  Here, when the vehicle is traveling on a highland, the upper limit opening degree Aegru is also set to a small opening degree, similar to the determination value ΔFegrp. Therefore, when the vehicle is traveling on a highland (shown by a solid line in FIG. 10), the EGR valve 25 is compared with a case where the vehicle is traveling on a lowland (illustrated by a dashed line in FIG. 10). This reaches the upper limit opening degree Aegru before the opening degree increases significantly (timing t10). Thus, when the EGR valve 25 is opened to the upper limit opening degree Aegru and is maintained at the upper limit opening degree Aegru for a predetermined time Td, when the change amount ΔFegr of the EGR flow remains less than the determination value ΔFegrp (timing t11) ), It is diagnosed that an abnormality has occurred in the EGR device 22, and the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(5) The upper limit opening Aegru when opening the EGR valve 25 is set to a smaller value as the atmospheric pressure is lower. For this reason, even when the vehicle is traveling in a high altitude area where the atmospheric pressure is low and the air density is low, the occurrence of misfire as described above can be suppressed by performing abnormality diagnosis with the EGR flow rate limited. become.

  In the present embodiment, the upper limit opening Aegru of the EGR valve 25 is variably set according to the atmospheric pressure, and the determination value ΔFegrp used for the abnormality diagnosis is also variably set according to the atmospheric pressure. ing. For this reason, for example, when the vehicle is traveling on a high altitude or the like, the upper limit opening degree of the EGR valve 25 is set to be small, and the determination value ΔFegrp is set to be small so that the abnormality diagnosis of the EGR device 22 is appropriately executed. Is possible.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the exhaust gas recirculation device abnormality diagnosis device according to the present invention will be described with reference to FIGS. 11 and 12. The present embodiment and the first embodiment are partially different from each other in the abnormality diagnosis process shown in FIG. In the following, this embodiment will be described focusing on such differences.

  Here, when the EGR valve 25 is once closed and then opened immediately, there is a response delay in the change in the EGR flow rate, so that the EGR flow rate becomes an amount corresponding to the opening after the closed drive. In some cases, the EGR valve 25 is driven to open before the pressure decreases. Therefore, in consideration of such a response delay of the EGR flow rate, the opening degree is maintained until a predetermined opening degree holding period Tc elapses after the EGR valve closing drive is completed as in the first embodiment. It is desirable. However, if the opening degree after the closing drive is maintained in this way, the state in which the opening degree of the EGR valve 25 is reduced, that is, the state in which the exhaust gas temperature is lowered, continues. There is a concern that the temperature will drop more than necessary. Therefore, it is desirable to suppress a decrease in the temperature of the exhaust purification catalyst 30 particularly in a situation where the temperature of the exhaust purification catalyst 30 is low, such as at the start of engine operation or low load operation.

Therefore, in the present embodiment, the opening degree holding period Tc is changed to be shorter as the temperature of the exhaust purification catalyst 30 is lower.
FIG. 11 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In the present embodiment, when the abnormality diagnosis process is started, it is first determined whether or not the catalyst bed temperature T, which is the temperature of the exhaust purification catalyst 30, is equal to or lower than a predetermined temperature Tm (step S502). Here, the catalyst bed temperature T is directly detected from the temperature sensor 33 as described above. The predetermined temperature Tm will be described later.

  When it is determined that the catalyst bed temperature T is higher than the predetermined temperature Tm (step S502: NO), the opening holding period Tc and the determination value ΔFegrp are changed according to the catalyst bed temperature T (step S504). .

  Here, the opening holding period Tc and the determination value ΔFegrp are set based on a map (FIG. 12) showing the relationship between the catalyst bed temperature T, the opening holding period Tc, and the determination value ΔFegrp. In this map, when the catalyst bed temperature T is higher than the predetermined temperature Tm, the opening degree holding period Tc is set to be shorter as the catalyst bed temperature T is lower. In addition, if the opening degree holding period Tc is changed in this way, the change amount ΔFegr of the EGR flow rate may be reduced. Therefore, considering this, the determination value ΔFegrp used for abnormality diagnosis is set to a small value. It is set. Therefore, in the present embodiment, in the map shown in FIG. 12, when the catalyst bed temperature T is higher than the predetermined temperature Tm, the determination value ΔFegrp is set to a smaller value as the catalyst bed temperature T is lower.

  After the opening degree holding period Tc and the determination value ΔFegrp are thus changed according to the catalyst bed temperature T, the process proceeds to step S210 shown in FIG. 3 and the EGR valve 25 is started to be closed. In the abnormality diagnosis process, the opening degree of the EGR valve 25 is maintained during the opening degree holding period Tc changed as described above until the opening driving is started after the closing driving of the EGR valve 25 is completed. The Further, the abnormality diagnosis of the EGR device 22 is executed by determining whether or not the change amount ΔFegr of the EGR flow rate is equal to or larger than the determination value ΔFegrp changed as described above.

  On the other hand, when it is determined that the catalyst bed temperature T is equal to or lower than the predetermined temperature Tm (step S502: YES), the EGR valve 25 corresponding to the forced drive process is prohibited from being closed (step S506). Then, the process proceeds to step S300 shown in FIG. 3, and the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state. And this process is once complete | finished. For example, when the opening temperature holding period Tc is set short to suppress the temperature reduction of the exhaust purification catalyst 30 when the catalyst bed temperature T is equal to or lower than the predetermined temperature Tm, the predetermined temperature Tm is The temperature is set to a temperature at which it becomes difficult to eliminate the response delay of the above-described EGR flow rate to the extent that there is no problem in executing the abnormality diagnosis. The predetermined temperature Tm is a value set in advance by experiments or the like.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(6) The driving mode of the EGR valve 25 when performing the forced driving process is set based on the catalyst bed temperature T, so that the temperature of the exhaust purification catalyst 30 is changed within a predetermined temperature range. That is, the opening holding period Tc for holding the opening until the opening driving is started after completing the closing driving of the EGR valve 25 is changed so as to be shorter as the catalyst bed temperature T is lower. The EGR valve 25 is driven based on the opening degree holding period Tc. Therefore, the temperature reduction of the exhaust purification catalyst 30 can be appropriately suppressed according to the catalyst bed temperature T.

  (7) When the catalyst bed temperature T is equal to or lower than the predetermined temperature Tm, the forced drive process is prohibited and the EGR valve 25 is set so that the opening of the EGR valve 25 becomes an opening set based on the engine operating state. I try to drive it. Therefore, an excessive temperature decrease of the exhaust purification catalyst 30 due to the execution of the forced drive process of the EGR valve 25 can be suppressed.

(Fifth embodiment)
A fifth embodiment of the exhaust gas recirculation apparatus abnormality diagnosis apparatus according to the present invention will be described below with reference to FIGS. The present embodiment and the first embodiment are partially different from each other in the abnormality diagnosis process shown in FIG. In the following, this embodiment will be described focusing on such differences.

  Here, in the forcible drive processing of the EGR valve 25, if the lower limit opening Aegrd is set to be small, the state in which the exhaust gas temperature is lowered continues. Therefore, depending on the temperature condition of the exhaust gas purification catalyst 30, the temperature decreases more than necessary. There is concern.

Therefore, in the present embodiment, the lower limit opening degree Aegrd of the EGR valve 25 is set according to the temperature of the exhaust purification catalyst 30.
FIG. 13 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In the present embodiment, when the abnormality diagnosis process is started, first, the lower limit opening degree Aegrd is set according to the catalyst bed temperature T that is the temperature of the exhaust purification catalyst 30 (step S602).

  Here, the lower limit opening degree Aegrd is set based on a map (FIG. 14) showing the relationship between the catalyst bed temperature T and the lower limit opening degree Aegrd. In this map, the lower limit opening degree Aegrd is set to be larger as the catalyst bed temperature T is lower.

  Thus, after the lower limit opening degree Aegrd is set according to the catalyst bed temperature T, the present process proceeds to step S210 shown in FIG. 3, and the EGR valve 25 is started to be closed. In the abnormality diagnosis process, the lower limit opening degree Aegrd set as described above is used as the target opening degree when the EGR valve 25 is driven to close.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(8) When the EGR valve 25 is driven to close to the lower limit opening Aegrd that is the target opening, the lower opening Aegrd is set to a larger opening as the catalyst bed temperature T is lower. Therefore, the lower the temperature of the exhaust purification catalyst 30 is, the more exhaust gas is allowed to flow into the catalyst, so that the temperature decrease of the catalyst can be appropriately suppressed.

(Sixth embodiment)
A sixth embodiment of the exhaust gas recirculation device abnormality diagnosis device according to the present invention will be described below with reference to FIG. The present embodiment and the first embodiment are partially different from each other in the abnormality diagnosis process shown in FIG. In the following, this embodiment will be described focusing on such differences.

  Here, when the opening degree of the EGR valve 25 is decreased to the lower limit opening degree, and the opening degree is maintained for a predetermined period (opening holding period Tc), normally, the EGR flow rate is constant corresponding to the lower limit opening degree. It will converge to the value. However, when the vehicle is in an unstable traveling state, for example, when the vehicle travels on a cobblestone road, the EGR flow rate may fluctuate without converging to a constant value. If the abnormality diagnosis is executed under such a situation where the EGR flow rate is fluctuating, there is a concern that the diagnosis accuracy may be lowered.

  Therefore, in the present embodiment, the opening of the EGR valve 25 is delayed until the EGR flow rate converges and reaches a stable state after the opening degree of the EGR valve 25 is reduced to the lower limit opening degree.

  FIG. 15 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In the present embodiment, when the abnormality diagnosis process is started, the EGR valve 25 is first started to be closed as in the abnormality diagnosis process in the first embodiment shown in FIG. 3 (step S710). . The EGR valve 25 is continuously closed until the EGR valve 25 is closed to the lower limit opening Aegrd which is a predetermined opening degree (step S720: NO), and when the EGR valve 25 is closed to the lower limit opening Aegrd ( Step S720: YES), the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd (Step S730). After the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd, the opening degree of the EGR valve 25 is maintained until the opening degree holding period Tc elapses (step S732: NO), and when the opening degree holding period Tc elapses. (Step S732: YES), it is determined whether or not the change amount ΔFegr of the EGR flow rate is stable (Step S734). Then, until the predetermined period Te has elapsed after the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd (step S736: NO), the determination as to whether or not the change amount ΔFegr of the EGR flow rate is stable continues. Done. Thus, the opening of the EGR valve 25 is delayed until the change amount ΔFegr of the EGR flow rate is stabilized. The predetermined period Te is set to a time when the temperature of the exhaust purification catalyst 30 may be lowered when the EGR valve 25 remains small for a predetermined period Te or longer, and is longer than the opening holding period Tc. Is set in advance.

  If the detected value of the change amount ΔFegr of the EGR flow rate is substantially constant, it is determined that the change amount ΔFegr of the EGR flow rate is stable (step S734: YES), and this processing is the previous step of FIG. The process proceeds to S240, and the opening driving of the EGR valve 25 is started.

  On the other hand, if the predetermined period Te elapses after the opening degree of the EGR valve 25 is maintained at the lower limit opening degree Aegrd while the change amount ΔFegr of the EGR flow rate is not stable (step S736: YES), the temperature of the exhaust purification catalyst 30 described above. Since there is a concern about the decrease, the closing drive of the EGR valve 25 is interrupted (step S738). Then, the present process is shifted to step S300 of FIG. 3 and the opening degree of the EGR valve 25 is set to the opening degree based on the engine operating state, and then the present process is temporarily ended.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(9) Since the opening of the EGR valve 25 is delayed until the EGR flow is stabilized after the EGR valve 25 is closed, the EGR flow associated with the opening is stabilized. Abnormalities can be diagnosed, and the diagnostic accuracy can be improved. Further, if the EGR flow rate is not stable after the predetermined period Te has elapsed, the forcible driving process is interrupted and the EGR valve 25 is driven so that the opening degree of the EGR valve 25 becomes an opening degree based on the engine operating state. Therefore, it is possible to prevent the temperature of the exhaust purification catalyst 30 from being lowered due to the opening degree of the EGR valve 25 remaining small for a long period of time.

(Seventh embodiment)
A seventh embodiment that embodies an abnormality diagnosis device for an exhaust gas recirculation device according to the present invention will be described below with reference to FIGS. 16 and 17. Note that this embodiment is different from the first embodiment in part of the abnormality diagnosis process shown in FIG. In the following, this embodiment will be described focusing on such differences.

  In general, the accuracy of the intake pressure sensor varies depending on the intake pressure, and the accuracy decreases as the intake pressure decreases. Therefore, when the amount of change in the EGR flow rate is estimated based on the detection value of the intake pressure sensor, a decrease in the accuracy of the intake pressure sensor affects the estimation.

Therefore, in this embodiment, the determination value ΔFegrp used for abnormality diagnosis of the EGR device 22 is changed according to the detection value of the intake pressure sensor 21.
FIG. 16 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In the present embodiment, when the abnormality diagnosis process is started, it is first determined whether or not the intake pressure PIM detected from the intake pressure sensor 21 is less than a predetermined pressure Pm (step S902). The predetermined pressure Pm will be described later.

  When it is determined that the intake pressure PIM detected from the intake pressure sensor 21 is equal to or higher than the predetermined pressure Pm (step S902: NO), the determination value ΔFegrp is changed according to the intake pressure PIM (step S904).

  Here, the determination value ΔFegrp is set based on a map (FIG. 17) showing the relationship between the intake pressure PIM and the determination value ΔFegrp. In this map, when the intake pressure PIM is equal to or higher than the predetermined pressure Pm, the smaller the intake pressure PIM, that is, the lower the accuracy of the intake pressure sensor 21 (shown by a dashed line in FIG. 17), the smaller the determination value ΔFegrp. Will be changed as follows. For example, even if it is assumed that the change amount ΔFegr of the EGR flow rate is smaller than the true value due to a decrease in accuracy of the intake pressure sensor 21, the determination value ΔFegrp according to the decrease in accuracy of the intake pressure sensor 21 in this way. By changing, it is possible to avoid making a false diagnosis of an abnormality due to a decrease in accuracy.

  Thus, after the determination value ΔFegrp is changed according to the intake pressure PIM, the present process proceeds to step S210 shown in FIG. 3 and the EGR valve 25 starts to be closed. In the abnormality diagnosis process, abnormality diagnosis of the EGR device 22 is executed by determining whether or not the change amount ΔFegr of the EGR flow rate is equal to or larger than the determination value ΔFegrp changed as described above.

  On the other hand, when it is determined that the intake pressure PIM is less than the predetermined pressure Pm (step S902: YES), the EGR valve 25 is prohibited from being closed (step S906). Then, the process proceeds to step S300 shown in FIG. 3, and the opening degree of the EGR valve 25 is set to an opening degree based on the engine operating state. And this process is once complete | finished. The predetermined pressure Pm is set to a pressure that is assumed that the accuracy of the intake pressure sensor 21 is low and abnormality diagnosis cannot be executed with a predetermined accuracy when the detected value of the intake pressure sensor 21 is less than the predetermined pressure Pm. The value is set in advance by experiment or the like.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(10) The abnormality diagnosis is executed using the determination value ΔFegrp that is changed so as to decrease as the intake pressure PIM, which is the detection value of the intake pressure sensor 21, decreases. Therefore, when there is a concern about a decrease in accuracy of the intake pressure sensor 21, that is, there is a deviation between the change amount ΔFegr of the EGR flow rate and its true value, and the change amount ΔFegr becomes smaller than the true value. Even if it is assumed that there is an error, it is possible to avoid making a misdiagnosis that indicates an abnormality due to the decrease in accuracy.

  (11) When the intake pressure PIM is less than the predetermined pressure Pm, the accuracy of the intake pressure sensor 21 is low, and the abnormality diagnosis cannot be executed with the predetermined accuracy. Therefore, the drive of the EGR valve 25 is stopped and the abnormality diagnosis is performed. Do not run. Accordingly, it is possible to avoid making a wrong diagnosis due to a decrease in accuracy of the intake pressure sensor 21.

(Eighth embodiment)
The eighth embodiment of the exhaust gas recirculation apparatus abnormality diagnosis apparatus according to the present invention will be described below with reference to FIGS. 18 and 19. FIG. Note that this embodiment is different from the first embodiment in part of the abnormality diagnosis process shown in FIG. In the following, this embodiment will be described focusing on such differences.

  FIG. 18 shows a processing procedure of abnormality diagnosis processing in the present embodiment. In this embodiment, when the abnormality diagnosis process is started, first, the throttle valve 16 and the supercharger 11 are driven so that the intake pressure PIM detected from the intake pressure sensor 21 becomes a predetermined pressure value Pu (step S1002). ). That is, the opening degree of the throttle valve 16 and the target supercharging pressure of the supercharger 11 are changed so that the intake pressure PIM becomes a predetermined pressure value Pu. Here, as the opening degree of the throttle valve 16 is reduced and the target supercharging pressure of the turbocharger 11 is reduced, the intake pressure PIM is reduced. The intake pressure PIM increases as the target supercharging pressure of the charger 11 increases.

FIG. 19 is a conceptual diagram showing the relationship between intake pressure PIM, intake pressure sensor accuracy, and detectability of abnormality diagnosis. The predetermined pressure value Pu is set based on the relationship shown in this conceptual diagram.
Here, as shown by a solid line in FIG. 19, the lower the intake pressure PIM, the larger the change amount ΔFegr of the EGR flow rate, and the EGR flow rate change amount ΔFegr greatly differs between when there is an abnormality and when there is no abnormality. Therefore, the detectability of abnormality diagnosis is improved. On the other hand, as described above, there is a concern that the accuracy of the intake pressure sensor 21 is reduced as the intake pressure PIM is lower (the chain line in FIG. 19). For this reason, the intake pressure PIM is low enough to improve the detectability of abnormality diagnosis, and is a predetermined pressure value Pu that is high enough to prevent the accuracy of the intake pressure sensor 21 from being reduced. It is desirable to perform abnormality diagnosis.

  Therefore, in the present embodiment, in order to adjust to the predetermined pressure value Pu that is the pressure of the intake system that is expected to improve the detectability of the abnormality diagnosis described above and that does not cause a decrease in the accuracy of the intake pressure sensor 21, The valve 16 and the supercharger 11 are driven.

  More specifically, when the intake pressure PIM is higher than the pressure value Pu, for example, the throttle valve 16 is driven to the closed side, while the target boost pressure of the supercharger 11 is decreased to reduce the intake pressure PIM. Reduce. On the other hand, when the intake pressure PIM is lower than the pressure value Pu, for example, the throttle valve 16 is driven to the open side, while the target boost pressure of the supercharger 11 is increased to reduce the intake pressure PIM. Raise.

  Then, after the intake pressure PIM is adjusted to the predetermined pressure value Pu, the present process proceeds to step S210 shown in FIG. 3, and the EGR valve 25 starts to be closed. The abnormality diagnosis process is executed in a state where the intake pressure of the intake system is the pressure value Pu.

According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) in the first embodiment.
(12) The intake air pressure of the intake system is adjusted to a predetermined pressure value Pu by the throttle valve 16 and the supercharger 11, and an abnormality diagnosis is executed under the adjusted intake pressure. Therefore, the abnormality diagnosis can be executed under conditions where the improvement of the detection performance of the abnormality diagnosis can be expected and the accuracy of the intake pressure sensor 21 is not a concern.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the third embodiment, the upper limit opening Aegru and the determination value ΔFegrp are variably set according to the atmospheric pressure Patm that is the traveling environment of the vehicle. In addition, the upper limit opening degree Aegru and the determination value ΔFegrp may be variably set according to the operating state of the engine. For example, when the catalyst regeneration process for recovering the purification function of the exhaust purification catalyst has been executed prior to the abnormality diagnosis, the upper limit opening Aegru and the determination value ΔFegrp are variably set so as to become smaller. To do. In such a form, the following effects can be obtained.

  (13) Since the upper limit opening degree Aegru when opening the EGR valve is set according to the operating state of the engine, the temperature is temporarily raised in order to recover the purification function of the exhaust purification catalyst. Even when the catalyst regeneration process is executed before the start of the abnormality diagnosis, the exhaust purification catalyst is more than necessary by performing the abnormality diagnosis in a state where the upper limit opening Aegru is set small and the EGR flow rate is limited. Thus, it is possible to execute an abnormality diagnosis while suppressing a temperature rise.

  Further, in this embodiment, in addition to variably setting the upper limit opening of the EGR valve according to the engine operating state as described above, the determination value ΔFegrp used for abnormality diagnosis is also variably set according to the engine operating state. Like to do. For this reason, even when the catalyst regeneration process is executed before the start of the abnormality diagnosis, the upper limit opening degree of the EGR valve is set to be small and the determination value ΔFegrp is set to be small so that the abnormality of the EGR device is set. Diagnosis can be performed appropriately.

  (14) Even if the catalyst regeneration process is executed before the start of the abnormality diagnosis, the misfire is suppressed by variably setting the upper limit opening Aegru and the determination value ΔFegrp of the EGR valve to be small. However, it is possible to appropriately execute the abnormality diagnosis of the EGR device.

  In the seventh and eighth embodiments, the abnormality diagnosis of the EGR device 22 is performed when the EGR valve 25 is opened. However, the EGR device is used only when the EGR valve 25 is closed instead of the opening drive. You may make it implement 22 abnormality diagnosis. Specifically, in the abnormality diagnosis process shown in FIG. 6, if the EGR flow rate change amount ΔFegr is equal to or greater than the determination value ΔFegrp (step 325: YES), it is diagnosed that no abnormality has occurred in the EGR device. To. On the other hand, when the opening holding period Tc has elapsed since the opening of the EGR valve was maintained at the lower limit opening Aegrd (step S334: YES), it is diagnosed that an abnormality has occurred in the EGR device. After diagnosing whether or not an abnormality has occurred in the EGR device in this way, the opening degree of the EGR valve is set to an opening degree based on the engine operating state, and the abnormality diagnosis process in this embodiment is ended. In such a form, an effect equivalent to the effect of (1) in the first embodiment can be obtained.

  In the second embodiment, the determination value ΔFegrp used for the abnormality diagnosis during the closed drive and the determination value ΔFegrp used for the abnormality diagnosis during the open drive are set to the same value, but are set to different values. May be.

  In the third embodiment, the upper limit opening degree Aegru and the determination value ΔFegrp are variably set according to the atmospheric pressure Patm. In addition, the upper limit opening degree Aegru and the determination value ΔFegrp may be variably set according to the traveling environment of the vehicle other than the atmospheric pressure Patm, such as the outside air temperature, and the atmospheric pressure Patm. It may be variably set according to the traveling environment of the vehicle other than the atmospheric pressure Patm. When the upper limit opening degree Aegru and the determination value ΔFegrp are variably set according to the outside air temperature, for example, the upper limit opening degree Aegru and the determination value ΔFegrp are set to be smaller as the outside air temperature is lower. Variable setting.

  In the third embodiment, the atmospheric pressure is directly detected by the atmospheric pressure sensor 41. However, the atmospheric pressure may be estimated based on the opening degree of the throttle valve and the intake pressure.

  In the third embodiment, the upper limit opening Aegru and the determination value ΔFegrp of the EGR valve 25 are variably set so that the lower the atmospheric pressure, the more the configuration is the first or It can also be adopted in the second embodiment.

  In the fourth embodiment, when the catalyst bed temperature T is higher than the predetermined temperature Tm, the lower the catalyst bed temperature T, the shorter the opening holding period Tc is changed and the smaller the determination value ΔFegrp is. Had to be set to. In addition, when the catalyst bed temperature T is higher than the predetermined temperature Tm, the determination value ΔFegrp is not changed as it is set in advance, and only the opening retention period Tc is changed as the catalyst bed temperature T is lower. You may make it do.

  In the fourth embodiment, when the catalyst bed temperature T is higher than the predetermined temperature Tm, the opening degree holding period Tc is changed, while when the catalyst bed temperature T is equal to or lower than the predetermined temperature Tm, the EGR valve 25 The open drive of was prohibited. In addition, it is possible to change only the opening holding period Tc based on the catalyst bed temperature T, and not to prohibit the EGR valve 25 from being opened. In such a form, an effect equivalent to the effect (6) in the fourth embodiment can be obtained. Further, when the catalyst bed temperature T is equal to or lower than the predetermined temperature Tm, only the prohibition of the opening drive of the EGR valve 25 may be performed, and the opening degree holding period Tc may not be changed. In such a form, an effect equivalent to the effect of (7) in the fourth embodiment can be obtained.

  In the fourth embodiment, the catalyst bed temperature T, which is the temperature of the exhaust purification catalyst 30, is detected directly from the temperature sensor 33. In addition, the catalyst bed temperature T may be estimated, for example, by providing an exhaust temperature sensor in the exhaust passage and estimating the catalyst bed temperature T based on the exhaust temperature detected by the exhaust temperature sensor. Good.

  In the fourth embodiment, the opening degree holding period Tc is changed to be shorter as the temperature of the exhaust purification catalyst 30 is lower, but such a configuration is used in the first to third embodiments. Can also be employed.

  In the fifth embodiment, the lower limit opening degree Aegrd is set to be larger as the catalyst bed temperature T is lower, but such a configuration can also be adopted in the first to fourth embodiments.

  In the sixth embodiment, after the EGR valve 25 has been closed, the EGR valve 25 is delayed until the EGR flow rate is stabilized, and the EGR flow rate is not stabilized even after a predetermined period Te has elapsed. In some cases, the forcible driving process is interrupted and the EGR valve 25 is driven so that the opening of the EGR valve 25 becomes the opening based on the engine operating state. Such a configuration may also be adopted in the first to fifth embodiments.

  In the seventh embodiment, when the intake pressure PIM is equal to or higher than the predetermined pressure Pm, the determination value ΔFegrp is changed so as to decrease as the intake pressure PIM decreases, and the intake pressure PIM is less than the predetermined pressure Pm. In some cases, the forced drive process of the EGR valve 25 is prohibited. In addition, it is not limited to the case where the intake pressure PIM is equal to or higher than the predetermined pressure Pm, and only the determination value ΔFegrp may be changed, and the forced drive processing of the EGR valve may not be prohibited. In such a form, an effect similar to the effect of (10) in the seventh embodiment can be obtained. Further, when the intake pressure PIM is less than the predetermined pressure Pm, only the prohibition of the EGR valve forced drive process may be performed, and the determination value ΔFegrp may not be changed. In such a form, an effect equivalent to the effect of (11) in the seventh embodiment can be obtained.

  In the seventh embodiment, the determination value ΔFegrp is changed to be smaller as the intake pressure PIM is lower, and when the intake pressure PIM is less than the predetermined pressure Pm, the drive of the EGR valve 25 is stopped to diagnose an abnormality. Was not executed. Such a configuration can also be employed in the first to sixth embodiments.

  In the eighth embodiment, the throttle valve 16 and the supercharger 11 are employed as adjusting means for adjusting the pressure of the intake system to the predetermined pressure value Pu. Only the throttle valve or the supercharger may be employed as the adjusting means.

  In the eighth embodiment, the intake pressure of the intake system is adjusted to the predetermined pressure value Pu by the throttle valve 16 and the supercharger 11, and the abnormality diagnosis is executed under the adjusted intake pressure. However, such a configuration can also be adopted in the first to sixth embodiments.

  The change amount ΔFegr of the EGR flow rate is calculated based on the intake pressure PIM that is a detection value from the intake pressure sensor 21. In addition, the change amount ΔFegr of the EGR flow rate may be calculated based on a detected value other than the intake pressure PIM, such as an intake air temperature detected from an intake air temperature sensor provided in the intake passage, and the intake pressure PIM. .

  In the first to sixth embodiments, the change amount ΔFegr of the EGR flow rate is detected based on the change of the intake pressure PIM detected by the intake pressure sensor 21, but the intake detected by the air flow meter 19 The change amount ΔFegr of the EGR flow rate can also be detected based on the change of the air amount. The change amount ΔFegr of the EGR flow rate may be detected based on changes in both the intake pressure PIM and the intake air amount.

  In the first to eighth embodiments, the opening degree of the EGR valve 25 is gradually changed so that the change in the EGR flow rate becomes slow during the forced driving process of the EGR valve 25. However, the EGR valve You may make it change the opening degree of swiftly. In such a form, effects other than the effect of (2) can be obtained in the first to eighth embodiments.

  -In the said 1st-8th embodiment, the conditions that the vehicle is decelerating and the fuel cut is performed are employ | adopted as execution conditions of the abnormality diagnosis of the EGR apparatus 22. FIG. In addition to these conditions, the execution condition may further include new conditions such as that the engine is in a steady operation state and that the engine is estimated to be completely warmed up from the engine water temperature. Good.

  In the first to eighth embodiments, the condition for executing the abnormality diagnosis is that the vehicle is decelerating and fuel cut is being executed. Instead, the engine is in steady operation. It is good also as an execution condition of abnormality diagnosis that it is in a state. In such a form, in the said 1st-8th embodiment, the effect according to the effect of (3) can be acquired.

  -Although this invention was actualized to the diesel engine, it is not restricted to this, For example, it can also apply to a gasoline engine. Even in such a case, an effect similar to the effect of the above embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Cylinder head, 3 ... Intake passage, 4a-4d ... Fuel injection valve, 5 ... Fuel addition valve, 6a-6d ... Exhaust port, 7 ... Intake manifold, 8 ... Exhaust manifold, 9 ... Common rail, 10 DESCRIPTION OF SYMBOLS ... Supply pump, 11 ... Supercharger (adjustment means), 16 ... Throttle valve (adjustment means), 17 ... Actuator, 18 ... Intercooler, 19 ... Air flow meter, 20 ... Throttle opening sensor, 21 ... Intake pressure sensor ( Change amount detecting means), 22 ... exhaust recirculation device (EGR device), 23 ... exhaust recirculation passage (EGR passage), 24 ... EGR cooler, 25 ... exhaust recirculation valve (EGR valve), 26 ... opening sensor, 27 ... fuel Supply pipe, 28 ... exhaust passage, 30 ... exhaust purification catalyst, 31 ... oxidation catalyst, 32 ... filter, 33 ... temperature sensor (temperature detection means), 40 ... control Location (valve drive means, variation detection means, diagnostic means, setting means), 41 ... atmospheric pressure sensor (atmospheric pressure detecting means), 42 ... outside air temperature sensor, 43 ... vehicle speed sensor.

Claims (19)

Exhaust gas recirculation is provided in the exhaust gas recirculation passage that connects the intake system of the in-vehicle internal combustion engine and the exhaust system provided with the exhaust purification catalyst, and adjusts the recirculation amount of the exhaust gas that is returned from the exhaust system to the intake system. About the exhaust gas recirculation device having a valve, in the exhaust gas recirculation device abnormality diagnosis device for diagnosing the presence or absence of the abnormality,
Valve drive means for executing forced drive processing for driving the exhaust gas recirculation valve to open once after the exhaust gas recirculation valve is driven to be closed when an abnormality diagnosis execution condition is satisfied;
A change amount detecting means for detecting a change amount of the exhaust gas recirculation amount associated with driving of the exhaust gas recirculation valve during the forced drive processing;
Diagnostic means for diagnosing that there is no abnormality when the amount of change in the exhaust gas recirculation amount due to the opening drive of the exhaust gas recirculation valve in the forced drive processing is greater than or equal to a predetermined determination value;
The valve driving means interrupts the forced driving process when the diagnosis means diagnoses that there is no abnormality, and the exhaust recirculation valve is opened based on the engine operating state so that the forced recirculation process is interrupted. An abnormality diagnosis device for an exhaust gas recirculation device, characterized by comprising: The abnormality diagnosis device for an exhaust gas recirculation device according to claim 1,
Prior to the abnormality diagnosis when the exhaust gas recirculation valve is opened, the diagnosis means diagnoses that there is no abnormality when the amount of change in the exhaust gas recirculation amount due to the closing operation of the exhaust gas recirculation valve is equal to or greater than a predetermined determination value. Yes,
When the valve drive means is diagnosed as having no abnormality in the abnormality diagnosis when the diagnosis means is closed, the forced drive process is interrupted and the opening of the exhaust gas recirculation valve is set based on the engine operating state. The exhaust gas recirculation valve is driven so that the abnormality is not diagnosed as being abnormal, and the forced drive processing is continued to perform an abnormality diagnosis at the time of open driving by the diagnostic means. Abnormality diagnosis device. In the exhaust gas recirculation apparatus abnormality diagnosis device according to claim 1 or 2,
The valve driving means is configured to open the exhaust gas recirculation valve until the predetermined upper limit opening degree is reached after the exhaust recirculation valve is once closed during the forced driving process,
An abnormality diagnosis device for an exhaust gas recirculation device, further comprising setting means for variably setting the upper limit opening and the determination value according to a traveling environment of a vehicle. The abnormality diagnosis device for an exhaust gas recirculation device according to claim 3,
The setting means includes an atmospheric pressure detecting means for detecting atmospheric pressure as a running environment of the vehicle, and the upper limit opening degree and the determination value are reduced as the atmospheric pressure detected by the atmospheric pressure detecting means is lower. An abnormality diagnosis device for an exhaust gas recirculation device, wherein these are variably set. In the exhaust gas recirculation apparatus abnormality diagnosis device according to claim 1 or 2,
The valve driving means is configured to open the exhaust gas recirculation valve to a predetermined upper limit opening degree after the exhaust recirculation valve is once closed and closed during the forced driving process,
An abnormality diagnosis device for an exhaust gas recirculation device, further comprising setting means for variably setting the upper limit opening and the determination value in accordance with an operating state of the in-vehicle internal combustion engine. In the exhaust gas recirculation apparatus abnormality diagnosis device according to claim 5,
When the catalyst regeneration process for recovering the purification function of the exhaust purification catalyst by increasing the temperature of the exhaust purification catalyst has been executed prior to the abnormality diagnosis, the upper limit opening degree and the determination value are respectively reduced. An abnormality diagnosis device for an exhaust gas recirculation device, characterized in that these are variably set. In the abnormality diagnosis apparatus for the exhaust gas recirculation apparatus according to any one of claims 1 to 6,
Temperature detection means for detecting the temperature of the exhaust purification catalyst,
The valve drive means sets the drive mode of the exhaust gas recirculation valve based on the detected temperature of the exhaust purification catalyst so that the temperature of the exhaust purification catalyst changes in a predetermined temperature range during the forced drive processing. An abnormality diagnosis device for an exhaust gas recirculation device. The abnormality diagnosis device for an exhaust gas recirculation device according to claim 7,
The valve driving means starts opening driving after holding the opening until a predetermined opening holding period elapses after completing the closing driving of the exhaust gas recirculation valve in the forced driving processing, An abnormality diagnosis device for an exhaust gas recirculation device, characterized in that this is changed so that the opening degree holding period becomes shorter as the temperature of the exhaust purification catalyst is lower. In the exhaust gas recirculation apparatus abnormality diagnosis device according to claim 7 or claim 8,
The valve drive means prohibits the forced drive process when the detected temperature of the exhaust purification catalyst is equal to or lower than a predetermined temperature, and the opening degree of the exhaust gas recirculation valve becomes an opening degree set based on the engine operating state. The exhaust gas recirculation valve is driven in the same manner as described above. In the abnormality diagnosis device for an exhaust gas recirculation device according to any one of claims 7 to 9,
The exhaust gas recirculation is characterized in that the valve driving means sets a lower limit opening, which is a target opening when the exhaust gas recirculation valve is closed, so that the lower the temperature of the detected exhaust purification catalyst is, the larger the lower limit opening is. Device abnormality diagnosis device. In the abnormality diagnosis apparatus of the exhaust gas recirculation apparatus according to any one of claims 1 to 10,
The valve drive means closes the exhaust recirculation valve until the opening degree of the exhaust gas recirculation valve reaches a predetermined opening degree during the forced driving process, and monitors the detected amount of change of the exhaust gas recirculation amount. While the opening of the exhaust gas recirculation valve is delayed until the change amount of the recirculation amount is stabilized, the forced driving process is interrupted when the change amount of the exhaust gas recirculation amount is not stable even after a predetermined period of time has elapsed. An abnormality diagnosis device for an exhaust gas recirculation apparatus, wherein the exhaust gas recirculation valve is driven so that the opening degree of the recirculation valve becomes an opening degree set based on an engine operating state. Exhaust gas provided with an exhaust gas recirculation passage that connects an exhaust system and an intake system of an on-vehicle internal combustion engine, and an exhaust gas recirculation valve that is provided in the exhaust gas recirculation passage and adjusts the recirculation amount of exhaust gas that is returned from the exhaust system to the intake system In the abnormality diagnosis device of the exhaust gas recirculation device that diagnoses the presence or absence of the abnormality of the recirculation device,
Valve drive means for executing a forced drive process for closing the exhaust gas recirculation valve when an abnormality diagnosis execution condition is satisfied;
A change amount detecting means for detecting a change amount of the exhaust gas recirculation amount associated with driving of the exhaust gas recirculation valve during the forced drive processing;
Diagnostic means for diagnosing that there is no abnormality when the amount of change in the exhaust gas recirculation amount accompanying the closed drive of the exhaust gas recirculation valve in the forced drive processing is equal to or greater than a predetermined determination value;
The valve driving means interrupts the forced driving process when the diagnosis means diagnoses that there is no abnormality, and the exhaust recirculation valve is opened based on the engine operating state so that the forced recirculation process is interrupted. An abnormality diagnosis device for an exhaust gas recirculation device, characterized by comprising: In the abnormality diagnosis apparatus of the exhaust gas recirculation apparatus according to any one of claims 1 to 12,
The change amount detection means includes an intake pressure sensor that detects an intake pressure, and estimates a change amount of the exhaust gas recirculation amount based on a detection value of the intake pressure sensor.
The diagnosis means changes the determination value so that the determination value becomes smaller as the detection value of the intake pressure sensor becomes smaller, and performs abnormality diagnosis based on the changed determination value. Diagnostic device. The abnormality diagnosis device for an exhaust gas recirculation device according to any one of claims 1 to 13,
The change amount detection means includes an intake pressure sensor that detects an intake pressure, and estimates a change amount of the exhaust gas recirculation amount based on a detection value of the intake pressure sensor.
The valve drive means prohibits the forced drive processing of the exhaust gas recirculation valve when the detected value of the intake pressure sensor is less than a predetermined pressure, so that the opening is set based on the engine operating state. An exhaust gas recirculation apparatus abnormality diagnosis device characterized in that the exhaust gas recirculation valve is driven. In the abnormality diagnosis apparatus of the exhaust gas recirculation apparatus according to any one of claims 1 to 12,
An adjustment means for adjusting the intake pressure so that the intake pressure becomes a predetermined pressure value in the forced drive processing;
The change amount detection means includes an intake pressure sensor that detects an intake pressure, and estimates a change amount of the exhaust gas recirculation amount based on a detection value of the intake pressure sensor.
An abnormality diagnosis of the exhaust gas recirculation apparatus is characterized in that the diagnosis means executes an abnormality diagnosis of the exhaust gas recirculation apparatus under the intake pressure of the intake system adjusted to have a predetermined pressure value by the adjusting means. apparatus. The abnormality diagnosis device for an exhaust gas recirculation device according to claim 15,
An abnormality diagnosis device for an exhaust gas recirculation device, wherein the adjusting means includes a throttle valve for adjusting an intake air amount. The abnormality diagnosis device for an exhaust gas recirculation device according to claim 15 or 16,
The abnormality diagnosis device for an exhaust gas recirculation device, wherein the adjustment means includes a supercharging pressure variable supercharger that supercharges intake air. In the exhaust gas recirculation device abnormality diagnosis device according to any one of claims 1 to 17,
The abnormality diagnosis device for an exhaust gas recirculation device, wherein the valve driving means gradually changes the opening degree of the exhaust gas recirculation valve so that the change in the exhaust gas recirculation amount becomes slow during the forced drive processing. The abnormality diagnosis device for an exhaust gas recirculation device according to any one of claims 1 to 18,
An abnormality diagnosis device for an exhaust gas recirculation apparatus, characterized in that the condition for executing the abnormality diagnosis includes that the vehicle is decelerating and fuel cut is being executed.

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