JP2014185542A - Filter abnormality detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance determination accuracy when determining an abnormality of a filter by using a PM sensor.SOLUTION: A filter abnormality detection device comprises: a filter arranged in an exhaust gas passage of an internal combustion engine and collecting particulate substances in an exhaust gas; a PM sensor for detecting an amount of the particulate substances in the exhaust gas at a downstream side of the filter; a PM sensor regeneration part which performs PM sensor regeneration processing which is the processing for removing the particulate substances from the PM sensor when the amount of the particulate substances deposited at the PM sensor reaches a prescribed amount or larger; and a determination part which determines that the filter is abnormal when a difference between an integrated value of the amount of the particulate substances flowing into the filter by a time point at which the next PM sensor regeneration processing is started from a time point at which the PM sensor regeneration processing is completed and a reference value is not smaller than a threshold.

Description

  The present invention relates to a filter abnormality detection device.

  A filter provided in the exhaust passage of the internal combustion engine for collecting particulate matter (hereinafter also referred to as PM) in the exhaust, and a PM sensor for detecting PM in the exhaust in the exhaust passage downstream of the filter; , May be provided. The PM sensor is a sensor that outputs an electrical signal corresponding to the amount of PM deposited on the PM sensor itself. For this reason, when the amount of PM deposited on the PM sensor reaches a predetermined value, regeneration of the PM sensor, which is a process of removing PM from the PM sensor, is performed. It is known that when the filter is abnormally cracked or chipped, the amount of PM deposited on the PM sensor changes according to the amount of PM discharged from the internal combustion engine. Further, it is known that even if the integrated value of the PM amount discharged from the internal combustion engine is the same, the amount of PM deposited on the PM sensor differs between when the filter is abnormal and when the filter is normal. (For example, refer to Patent Document 1).

By the way, if the operation state in which PM accumulated in the filter is oxidized by NO ₂ in the exhaust continues, the amount of PM flowing out downstream is reduced even if the filter is abnormal. For this reason, since the amount of PM flowing out from the filter is reduced, even if the filter is abnormal, the amount of PM reaching the PM sensor can be reduced. Then, the relationship between the integrated value of the PM amount discharged from the internal combustion engine and the PM amount accumulated on the PM sensor changes.

Further, although it is conceivable to determine the abnormality of the filter based on the number of regeneration times of the PM sensor, NO ₂ may reduce the number of regeneration times of the PM sensor. Further, when a transient operation in which the amount of PM flowing into the filter changes is performed, the number of regenerations of the PM sensor also changes. Therefore, if it is determined that the filter is abnormal based only on the number of regenerations of the PM sensor, the determination accuracy may be lowered. Further, the abnormality of the filter can be determined by the differential pressure between the upstream side and the downstream side of the filter. However, since the differential pressure changes depending on the amount of PM accumulated on the filter, the determination accuracy may be lowered. . In addition, when determining the abnormality of the filter based on the detection value of the PM sensor downstream from the filter, it is necessary to obtain the amount of PM accumulated in the PM sensor with high accuracy. The effect of. For this reason, if the detection value of the PM sensor varies, the determination accuracy of the filter abnormality may be lowered.

JP 2012-017678 A JP 2012-122399 A

  The present invention has been made in view of the above-described problems, and an object thereof is to improve the determination accuracy when determining a filter abnormality using a PM sensor.

In order to achieve the above object, the present invention provides:
A filter provided in an exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust;
A PM sensor for detecting the amount of particulate matter in the exhaust gas downstream of the filter;
A filter inflow PM amount detection device that detects or estimates the amount of particulate matter in the exhaust gas upstream of the filter;
In the filter abnormality detection device comprising:
A PM sensor regeneration unit that performs a PM sensor regeneration process, which is a process of removing particulate matter from the PM sensor when the amount of particulate matter deposited on the PM sensor exceeds a predetermined amount;
The integrated value of the amount of particulate matter detected or estimated by the filter inflow PM amount detection device from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started, and a reference value A determination unit that determines that the filter is abnormal when the difference is equal to or greater than a threshold;
Is provided.

  Here, when an abnormality such as a crack or a chip occurs in the filter, the amount of PM passing through the filter changes according to the amount of PM accumulated in the filter. That is, as the amount of accumulated PM in the filter increases, the resistance of a portion where no abnormality such as cracking or chipping occurs is relatively increased, so that more exhaust gas flows into the portion where the abnormality occurs. For this reason, more PM comes to flow out from the location where the abnormality has occurred. On the other hand, when the filter is normal, the amount of PM passing through the filter hardly changes even if the amount of accumulated PM in the filter changes. For this reason, the ratio of PM passing through the filter (ratio of the amount of PM flowing out of the filter to the amount of PM flowing into the filter; hereinafter also referred to as PM passing rate) is substantially constant when the filter is normal. However, when the filter is abnormal, it changes according to the amount of accumulated PM in the filter.

  By the way, the PM sensor outputs an output corresponding to the amount of PM deposited on the PM sensor itself. If the amount of PM accumulated on the PM sensor becomes too large, output according to the PM amount becomes difficult. Therefore, when the amount of PM accumulated on the PM sensor exceeds a predetermined amount, the PM sensor is regenerated. The process removes PM from the PM sensor. Note that the predetermined amount is a PM accumulation amount that requires PM sensor regeneration processing.

  Here, regardless of whether or not the filter is normal, the PM amount flowing out from the filter increases as the amount of PM flowing into the filter increases. However, the ratio of PM passing through the filter is larger when the filter is abnormal than when the filter is normal.

  If the filter is normal, the ratio of PM passing through the filter is constant regardless of the PM accumulation amount in the filter, so the PM amount reaching the PM sensor changes according to the PM amount flowing into the filter. Therefore, if the filter is normal, the integrated value of the PM amount flowing into the filter from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started (hereinafter also referred to as the PM inflow amount integrated value). .), The amount of accumulated PM in the PM sensor changes. For this reason, the PM inflow amount integrated value until the PM accumulation amount in the PM sensor reaches a predetermined amount becomes a substantially constant value.

  On the other hand, if the filter is abnormal, the ratio of PM passing through the filter changes depending on the amount of PM accumulated in the filter. Therefore, the amount of PM reaching the PM sensor depends on the amount of PM flowing into the filter and the ratio of PM passing through the filter. Change. Therefore, if the filter is abnormal, the PM accumulation amount in the PM sensor changes according to the PM inflow integrated value and the PM passing rate. For this reason, the PM inflow amount integrated value until the PM accumulation amount in the PM sensor reaches a predetermined amount changes according to the PM passing rate.

Therefore, the PM value integrated value (PM inflow integrated value) flowing into the filter from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started is compared with the reference value, and PM If it is known that the integrated amount of inflow has changed, it can be determined that the filter is abnormal. Thus, by determining the abnormality of the filter based on the integrated value of the PM amount flowing into the filter, it is possible to determine the abnormality of the filter even during the transient operation.

  The reference value is, for example, the amount of particulate matter detected or estimated by the filter inflow PM amount detection device from the previous “PM sensor regeneration process is completed until the next PM sensor regeneration process is started. It is good also as "integrated value of". The reference value is, for example, the amount of particulate matter detected or estimated by the filter inflow PM amount detection device from the time when the previous PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started. It is good also as "integrated value of". Further, the reference value is detected or estimated in the filter inflow PM amount detection device from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started when the filter is in a normal range. The integrated value of the amount of the particulate matter ”. The threshold value can be the difference when the filter is abnormal.

  It should be noted that the period “from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started” may be an interval of the PM sensor regeneration process. The period may be time or travel distance.

In the present invention, when the amount of NO ₂ in the exhaust gas flowing into the filter is larger than a predetermined amount, the determination unit starts the next PM sensor regeneration process from the time when the PM sensor regeneration process is completed. When the value obtained by subtracting the integrated value of the amount of particulate matter detected or estimated by the filter inflow PM amount detection device up to the reference value by the time point is equal to or less than a negative threshold value, the filter is abnormal. It can be determined that there is.

Here, the predetermined amount can be the amount of NO ₂ that reduces the amount of PM deposited on the filter. Note that the NO ₂ amount may be an amount per unit time or may be an amount in a predetermined period. Further, the NO ₂ amount may be the NO ₂ concentration. Here, when NO ₂ flows into the filter, PM accumulated in the filter is oxidized, so that the amount of PM accumulated in the filter can be reduced. Even if the amount of accumulated PM in the filter decreases, the ratio of PM passing through the filter does not change when the filter is normal. If the filter is normal, the integrated value of the PM amount flowing into the filter (PM inflow integrated value) does not change from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started. .

  On the other hand, when the filter is abnormal, the ratio of PM passing through the filter decreases as the amount of PM deposited on the filter decreases. For this reason, the PM inflow amount integrated value until the PM accumulation amount in the PM sensor reaches a predetermined amount increases. Therefore, a value obtained by subtracting the PM inflow integrated value from the reference value becomes a negative value. The smaller this value (the larger the absolute value), the greater the amount of change in the amount of PM that flows out of the filter. Therefore, the threshold value is set to a negative value, and the difference between the threshold value and the difference becomes abnormal. It can be determined whether or not.

  In the present invention, the determination unit detects or estimates the reference value in the filter inflow PM amount detection device from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started. It can be the integrated value of the amount of the particulate matter that has been detected or estimated last time.

That is, the previous value and the current value of the PM inflow integrated value are compared. If the filter is normal, the PM inflow integrated value hardly changes, so the previous value and the current value of the PM inflow integrated value are almost the same. For this reason, the difference between the previous value and the current value of the PM inflow integrated value is small. On the other hand, if the filter is abnormal, the PM inflow integrated value changes, so a difference occurs between the previous value and the current value of the PM inflow integrated value. Therefore, if this difference is greater than or equal to the threshold, it can be determined that the filter is abnormal. Note that the integrated value of the amount of particulate matter detected or estimated last time may be an integrated value of the amount of particulate matter detected or estimated during the previous operation of the internal combustion engine.

  ADVANTAGE OF THE INVENTION According to this invention, the determination precision when determining abnormality of a filter using PM sensor can be improved.

It is a figure which shows schematic structure of the internal combustion engine which concerns on an Example. It is the figure which showed the relationship between the accumulation amount of PM in a filter, and the ratio (PM passage rate) of PM which passes a filter with respect to PM which flows into this filter. 3 is a time chart showing transitions of the vehicle speed, the PM accumulation amount in the filter 3, and the PM amount flowing into the filter (PM inflow amount) according to the first embodiment. It is the figure which showed the relationship between the detection value of PM sensor when the filter which concerns on Example 1 is normal, and a filter is abnormal, and the integrated value of PM amount which flows into a filter. It is the figure which showed the relationship of the variation | change_quantity of PM inflow amount integrated value with the case where the filter which concerns on Example 1 is normal, and abnormal. 6 is a flowchart illustrating a flow of filter abnormality detection according to the first embodiment. 6 is a time chart showing transitions of a vehicle speed, a PM accumulation amount in the filter 3, and a PM amount flowing into the filter (PM inflow amount) according to the second embodiment. It is the figure which showed the relationship between the detection value of PM sensor when the filter which concerns on Example 2 is normal, and a filter is abnormal, and the integrated value of PM amount which flows into a filter. It is the figure which showed the relationship of the variation | change_quantity of PM inflow amount integrated value with the case where the filter which concerns on Example 2 is normal, and abnormal. 12 is a flowchart illustrating a flow of filter abnormality detection according to the second embodiment. 12 is a flowchart illustrating a flow of filter abnormality detection according to the third embodiment. 10 is a time chart showing changes in vehicle speed, PM accumulation amount in the filter 3, and PM amount flowing into the filter (PM inflow amount) according to the fourth embodiment. It is the figure which showed the relationship between the detection value of PM sensor when the filter which concerns on Example 4 is normal, and a filter is abnormal, and the integrated value of PM amount which flows into a filter. It is the figure which showed the relationship of the variation | change_quantity of PM inflow amount integrated value with the case where the filter which concerns on Example 4 is normal, and abnormal. 12 is a flowchart illustrating a flow of filter abnormality detection according to the fourth embodiment. 10 is a time chart showing changes in vehicle speed, PM accumulation amount in the filter 3, and PM amount flowing into the filter (PM inflow amount) according to the fifth embodiment. It is the figure which showed the relationship between the detection value of PM sensor when the filter which concerns on Example 5 is normal, and a filter is abnormal, and the integrated value of PM amount which flows into a filter. It is the figure which showed the relationship of the variation | change_quantity of PM inflow amount integrated value with the case where the filter which concerns on Example 5 is normal, and abnormal. 10 is a flowchart illustrating a flow of filter abnormality detection according to the fifth embodiment. 10 is a flowchart showing a flow of filter abnormality detection according to Embodiment 6.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

<Example 1>
FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine according to an embodiment. Although the internal combustion engine 1 in the present embodiment is a gasoline engine, a diesel engine may be used. An exhaust passage 2 is connected to the internal combustion engine 1. The exhaust passage 2 is provided with a filter 3 that collects particulate matter (PM) in the exhaust.

  A PM sensor 4 for detecting the amount of PM in the exhaust gas flowing out from the filter 3 is provided in the exhaust passage 2 downstream of the filter 3. The PM sensor 4 has a pair of electrodes, and outputs a signal corresponding to the amount of PM by utilizing the change in resistance between the electrodes according to the amount of PM attached (deposited) between the electrodes. To do. Based on this signal, the amount of PM passing through the filter 3 per unit time can be detected. Note that the PM amount passing through the filter 3 in a predetermined period may be detected.

  A PM sensor 5 is also provided in the exhaust passage 2 upstream of the filter 3. According to this PM sensor 5, the amount of PM flowing into the filter 3 per unit time can be detected. Note that the amount of PM flowing into the filter 3 in a predetermined period may be detected. In this embodiment, the PM amount flowing into the filter 3 is detected by the PM sensor 5, but instead, the amount of PM discharged from the internal combustion engine 1 based on the operating state of the internal combustion engine 1 is detected. The PM amount may be used as the PM amount flowing into the filter 3. The relationship between the operating state of the internal combustion engine 1 (for example, engine speed and engine load) and the amount of PM discharged from the internal combustion engine 1 can be obtained in advance by experiments or simulations. In this embodiment, the PM sensor 5 corresponds to the filter inflow PM amount detection device in the present invention.

  The exhaust passage 2 is provided with a differential pressure sensor 14 that detects the difference between the pressure in the exhaust passage 2 upstream of the filter 3 and the pressure in the exhaust passage 2 downstream of the filter 3. . According to the differential pressure sensor 14, it is possible to detect a pressure difference between the upstream side and the downstream side of the filter 3 (hereinafter also referred to as filter differential pressure).

  The internal combustion engine 1 configured as described above is provided with an ECU 10 that is an electronic control unit for controlling the internal combustion engine 1. In addition to the above sensors, the ECU 10 includes an accelerator opening sensor 12 for detecting an engine load by outputting an electric signal corresponding to the amount of depression of the accelerator pedal 11, and a crank position sensor 13 for detecting the engine speed. Connected via electric wiring, the output signals of these various sensors are input to the ECU 10.

  Moreover, ECU10 controls the internal combustion engine 1 based on the detection value by each input sensor. For example, the ECU 10 calculates the amount of PM flowing out from the filter 3 per unit time based on the output signal of the PM sensor 4. The relationship between the output signal of the PM sensor 4 and the PM amount flowing out from the filter 3 may be mapped in advance. In this embodiment, the abnormality of the filter 3 is detected based on the output signal of the PM sensor 4.

  Here, when an abnormality such as a crack or a chip occurs in the filter 3, the PM passes through the part where the crack or the chip is generated, so that the amount of PM flowing out to the downstream side of the filter 3 increases. For this reason, the amount of PM per unit time detected downstream of the filter 3 increases. That is, the detection value of the PM sensor 4 varies depending on the state of the filter 3.

  FIG. 2 is a diagram showing the relationship between the amount of PM accumulated in the filter 3 and the ratio of PM passing through the filter 3 to the PM flowing into the filter 3 (PM passing rate). A solid line indicates a case where the filter 3 is normal, and a broken line indicates a case where the filter 3 is abnormal. When the filter 3 is normal, the PM passing rate is substantially constant at a relatively low value regardless of the amount of PM accumulated in the filter 3. On the other hand, when the filter 3 is abnormal, the PM passing through rate increases as the PM accumulation amount in the filter 3 increases. Here, when an abnormality such as a crack occurs in the filter 3, PM passes through the cracked portion. And if PM accumulation amount increases, since exhaust will pass through the cracked part where resistance is smaller, PM amount which passes the filter 3 will increase.

  For this reason, when the filter 3 is abnormal, the amount of PM deposited on the PM sensor 4 per unit time (hereinafter also referred to as PM deposition rate) increases. Here, when the amount of accumulated PM in the PM sensor 4 exceeds a predetermined amount, a PM sensor regeneration process, which is a process for removing PM from the PM sensor 4, is performed. This PM sensor regeneration process is performed by raising the temperature of the PM sensor 4 to a temperature at which PM is oxidized. The predetermined amount here is determined so as to maintain the accuracy of the detection value of the PM sensor within an allowable range.

  When the filter 3 is abnormal, as shown in FIG. 2, the PM passing rate increases as the PM deposition amount in the filter 3 increases. Therefore, the PM deposition rate on the PM sensor 4 with time elapses. Can be large. For this reason, when the filter 3 is abnormal, the frequency of performing the PM sensor regeneration process may gradually increase. On the other hand, when the filter 3 is normal, the PM passing rate hardly changes, so the PM deposition rate on the PM sensor 4 is also substantially constant. For this reason, when the filter 3 is normal, the frequency of performing the PM sensor regeneration processing is constant.

  Here, FIG. 3 is a time chart showing transitions of the vehicle speed, the PM accumulation amount in the filter 3, and the PM amount (PM inflow amount) flowing into the filter 3 according to the present embodiment. FIG. 4 is a diagram showing the relationship between the detected value of the PM sensor 4 when the filter 3 according to the present embodiment is normal and when the filter 3 is abnormal, and the integrated value of the PM amount flowing into the filter 3. It is. In FIG. 3, the PM inflow amount changes in accordance with the vehicle speed. Further, the PM accumulation amount in the filter 3 increases due to the PM discharged from the internal combustion engine 1. In FIG. 4, the PM sensor regeneration process is performed at the time indicated by “regeneration”.

  When the detection value of the PM sensor 4 is equal to or greater than the threshold value, the PM sensor regeneration process is performed, so that the detection value of the PM sensor 4 returns to zero. Note that until a certain amount of PM is deposited on the PM sensor 4, no current flows between the pair of electrodes included in the PM sensor, so the detection value does not increase. That is, the detection value starts increasing after a certain amount of PM is accumulated and current flows between the pair of electrodes provided in the PM sensor 4. Thereafter, the detected value increases in accordance with the amount of PM in the exhaust gas. Further, after the internal combustion engine 1 is started, a PM sensor regeneration process for removing PM accumulated on the PM sensor 4 when the internal combustion engine 1 was operated last time is performed once. In this embodiment, the ECU 10 that performs the PM sensor regeneration process corresponds to the PM sensor regeneration section in the present invention.

  Here, regardless of whether or not the filter 3 is normal, the PM amount flowing out from the filter 3 increases as the PM amount flowing into the filter 3 (PM inflow amount) increases. However, the PM passing rate is larger when the filter 3 is abnormal than when the filter 3 is normal.

If the filter 3 is normal, the PM passing rate is constant regardless of the PM accumulation amount in the filter 3, so the PM amount reaching the PM sensor 4 changes according to the PM inflow amount. Therefore, if the filter 3 is normal, the PM accumulation amount in the PM sensor 4 is the sum of the PM amount flowing into the filter 3 from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started. It changes according to the value (PM inflow amount integrated value). For this reason, the PM inflow amount integrated value until the PM accumulation amount in the PM sensor 4 reaches a predetermined amount becomes a substantially constant value. Therefore, in FIG. 4, when the filter 3 is normal, the PM sensor regeneration process is performed at substantially the same interval.

  On the other hand, if the filter 3 is abnormal, the PM passing rate changes depending on the amount of PM accumulated in the filter 3. For this reason, the amount of PM reaching the PM sensor 4 changes according to the PM inflow amount and the PM passing rate. Therefore, if the filter 3 is abnormal, the PM accumulation amount in the PM sensor changes in accordance with the PM inflow amount integrated value and the PM passing rate. For this reason, the PM inflow amount integrated value until the PM accumulation amount in the PM sensor reaches a predetermined amount changes according to the PM passing rate. Therefore, in FIG. 4, when the filter 3 is abnormal, the interval at which the PM sensor regeneration process is performed gradually decreases.

  From the above, the integrated value of the PM amount that has flowed into the filter 3 from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started (PM inflow amount integrated value) is the case where the filter 3 is normal. However, when the filter 3 is abnormal, it becomes gradually smaller.

  Therefore, if the PM inflow integrated value is compared with the reference value and it is known that the PM inflow integrated value has changed during this period, it can be determined that the filter 3 is abnormal.

  The reference value may be, for example, the PM inflow integrated value obtained last time. Further, the reference value may be a PM inflow integrated value when the filter 3 is in a normal range. The reference value in this case is obtained in advance by experiments or simulations and stored in the ECU 10. The reference value is not limited to the PM inflow integrated value obtained last time, but may be the PM inflow integrated value obtained before that. In this case, it may be the PM inflow amount integrated value obtained when the operating state of the internal combustion engine 1 is different, or may be the PM inflow amount integrated value obtained when the PM inflow amount is different. Furthermore, the PM accumulation amount in the filter 3 may be different. If the filter 3 is normal, even if the operation state of the internal combustion engine 1 is different, the operation state in which the PM inflow amount is different, or even if the PM accumulation amount in the filter 3 is different, the PM Since the inflow amount integrated values are substantially equal, the PM inflow amount integrated value obtained previously can be used as the reference value.

  In this embodiment, every time the PM sensor regeneration process is performed, the amount of PM flowing into the filter 3 from the time when the previous PM sensor regeneration process is completed to the time when the current PM sensor regeneration process is started is calculated. An integrated value (PM inflow amount integrated value) is obtained, the previous PM inflow amount integrated value is compared with the current PM inflow amount integrated value, and if the decrease amount of the PM inflow amount integrated value is less than the threshold, the filter 3 is If it is determined that the amount of decrease in the PM inflow integrated value is equal to or greater than the threshold value, it is determined that the filter 3 is abnormal. This threshold value is obtained in advance by experiment or simulation as a lower limit value of the decrease amount of the PM inflow integrated value when the filter 3 is abnormal, and is stored in the ECU 10.

  FIG. 5 is a diagram illustrating the relationship between the amount of change in the PM inflow integrated value when the filter 3 according to the present embodiment is normal and when it is abnormal. A value obtained by subtracting the current PM inflow integrated value from the previous PM inflow integrated value is used as the amount of change in the PM inflow integrated value. If the filter 3 is normal, the change amount of the PM inflow amount integrated value is close to 0, but if the filter 3 is abnormal, the change amount of the PM inflow amount integrated value is equal to or greater than the threshold value.

FIG. 6 is a flowchart showing a flow of abnormality detection of the filter 3 according to the present embodiment. This routine is executed by the ECU 10 every predetermined time.

  In step S101, it is determined whether a precondition for performing abnormality detection of the filter 3 is satisfied. For example, it is determined whether the PM sensor 4 is normal. A known technique can be used to determine whether the PM sensor 4 is normal. If an affirmative determination is made in step S101, the process proceeds to step S102. On the other hand, if a negative determination is made, this routine is terminated.

  In step S102, it is determined whether the PM sensor 4 is active. In this step, it is determined whether or not the temperature of the PM sensor 4 is a temperature suitable for PM detection. For this, a known technique can be used. In this step, it may be determined whether the PM sensor regeneration process has been completed and the temperature of the PM sensor 4 has decreased to a temperature at which PM can be detected. If an affirmative determination is made in step S102, the process proceeds to step S103. On the other hand, if a negative determination is made, step S102 is executed again.

  In step S103, integration of the PM amount flowing into the filter 3 is started. The PM amount flowing into the filter 3 from this step is defined as the first PM inflow amount, and the integrated value thereof is defined as the first PM inflow amount integrated value. The amount of PM flowing into the filter 3 may be detected by the PM sensor 5 or may be estimated based on the operating state of the internal combustion engine 1.

  In step S104, it is determined whether PM sensor regeneration processing has been performed. If an affirmative determination is made in step S104, the process proceeds to step S105. On the other hand, if a negative determination is made, step S104 is executed again.

  In step S105, the integration of the first PM inflow amount is terminated, and the integration of the next PM inflow amount is started. In addition, let PM amount which flows in into the filter 3 from this step be 2nd PM inflow amount, and let the integrated value be 2nd PM inflow amount integrated value.

  In step S106, it is determined whether PM sensor regeneration processing has been performed. If an affirmative determination is made in step S106, the process proceeds to step S107. On the other hand, if a negative determination is made, step S106 is executed again.

  In step S107, the integration of the second PM inflow amount ends.

  In step S108, it is determined whether or not a value obtained by subtracting the second PM inflow integrated value from the first PM inflow integrated value is less than a threshold value. This threshold value is obtained in advance by experiment or simulation or the like and stored in the ECU 10 as a lower limit value obtained by subtracting the second PM inflow integrated value from the first PM inflow integrated value when the filter 3 is abnormal. . In this step, it is determined whether or not the change amount of the PM inflow amount integrated value is less than the threshold value.

  If an affirmative determination is made in step S108, the process proceeds to step S109 and it is determined that the filter 3 is normal. On the other hand, if a negative determination is made in step S108, the process proceeds to step S110, where it is determined that the filter 3 is abnormal. In this embodiment, the ECU 10 that processes step S108 and subsequent steps corresponds to the determination unit in the present invention.

As described above, according to the present embodiment, the abnormality of the filter 3 can be determined with high accuracy by comparing the amount of change in the PM inflow amount integrated value with the threshold value. Further, since it is not necessary to accurately determine the amount of PM deposited on the PM sensor 4, it is difficult to be affected by variations in the detection value of the PM sensor 4. Further, by determining the abnormality of the filter 3 based on the integrated value of the PM amount flowing into the filter 3, the abnormality of the filter 3 is determined even during transient operation in which the PM amount flowing into the filter 3 can change. can do.

<Example 2>
In this embodiment, the abnormality of the filter 3 is detected based on the change amount of the PM inflow integrated value when the PM collected by the filter 3 is oxidized by NO ₂ or the like. Other devices and the like are the same as those in the first embodiment, and thus description thereof is omitted.

Here, the PM collected by the filter 3 is oxidized and removed depending on the state of the exhaust. For example, when the temperature of the filter 3 is high to some extent, PM is oxidized by NO ₂ in the exhaust gas flowing into the filter 3. Even in such a case, if the filter 3 is normal, the PM amount passing through the filter 3 is hardly changed, and therefore the PM inflow amount integrated value is also substantially constant. On the other hand, if the filter 3 is abnormal, the PM amount passing through the filter 3 decreases due to the decrease in the PM accumulation amount in the filter 3, and the PM inflow integrated value increases.

Here, FIG. 7 is a time chart showing transitions of the vehicle speed, the PM accumulation amount in the filter 3, and the PM amount (PM inflow amount) flowing into the filter 3 according to the present embodiment. FIG. 8 is a diagram showing the relationship between the detected value of the PM sensor 4 when the filter 3 is normal and when the filter 3 is abnormal, and the integrated value of the PM amount flowing into the filter 3 according to the present embodiment. It is. In FIG. 7, the PM inflow amount changes in accordance with the vehicle speed. Further, the amount of PM deposited on the filter 3 decreases due to oxidation by NO ₂ .

  Thus, the integrated value of the PM amount that has flowed into the filter 3 from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started (PM inflow amount integrated value) is normal for the filter 3. In this case, it becomes substantially constant, but gradually increases when the filter 3 is abnormal. Therefore, it can be determined that the filter 3 is abnormal because the PM inflow integrated value has increased.

  In this embodiment, every time the PM sensor regeneration process is performed, the amount of PM flowing into the filter 3 from the time when the previous PM sensor regeneration process is completed to the time when the current PM sensor regeneration process is started is calculated. An integrated value (PM inflow integrated value) is obtained. Further, the difference between the previous PM inflow amount integrated value and the current PM inflow amount integrated value is obtained. If this difference is larger than the threshold value, it is determined that the filter 3 is normal. It is determined that the filter 3 is abnormal. This threshold value is obtained in advance by experiment or simulation as an upper limit value of the difference between the previous PM inflow amount integrated value and the current PM inflow amount integrated value when the filter 3 is abnormal, and is stored in the ECU 10. Note that the threshold according to the present embodiment is a negative value. Similarly to the first embodiment, the PM inflow amount integrated value when the filter 3 is in a normal range may be compared with the current PM inflow amount integrated value. Further, not only the PM inflow amount integrated value obtained last time but also the PM inflow amount integrated value obtained before that time may be compared with the current PM inflow amount integrated value.

  FIG. 9 is a diagram illustrating the relationship between the amount of change in the PM inflow integrated value when the filter 3 according to the present embodiment is normal and when it is abnormal. A value obtained by subtracting the current PM inflow integrated value from the previous PM inflow integrated value is used as the amount of change in the PM inflow integrated value. If the filter 3 is normal, the change amount of the PM inflow amount integrated value is close to 0, but if the filter 3 is abnormal, the change amount of the PM inflow amount integrated value is equal to or less than the threshold value.

FIG. 10 is a flowchart showing a flow of abnormality detection of the filter 3 according to the present embodiment. This routine is executed by the ECU 10 every predetermined time. In addition, about the step where the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted. Further, this routine may be executed only when the amount of NO ₂ in the exhaust gas flowing into the filter is larger than a predetermined amount. That is, this routine may be executed only when the PM accumulation amount in the filter 3 is in a decreasing state.

  In the present embodiment, step S201 is processed after step S107. In step S201, it is determined whether or not a value obtained by subtracting the second PM inflow amount integrated value from the first PM inflow amount integrated value is larger than a threshold value. This threshold value is obtained in advance by experiment or simulation as an upper limit value obtained by subtracting the second PM inflow integrated value from the first PM inflow integrated value when the filter 3 is abnormal, and is stored in the ECU 10. . The threshold value is a negative value. In this step, it is determined whether or not the change amount of the PM inflow amount integrated value is larger than the threshold value.

  When an affirmative determination is made in step S201, the process proceeds to step S109 and it is determined that the filter 3 is normal. On the other hand, if a negative determination is made in step S201, the process proceeds to step S110, where it is determined that the filter 3 is abnormal. In this embodiment, the ECU 10 that processes step S201 and subsequent steps corresponds to the determination unit in the present invention.

  As described above, according to the present embodiment, the abnormality of the filter 3 can be determined with high accuracy by comparing the amount of change in the PM inflow amount integrated value with the threshold value. Further, since it is not necessary to accurately determine the amount of PM deposited on the PM sensor 4, it is difficult to be affected by variations in the detection value of the PM sensor 4. Further, even when the PM accumulation amount in the filter 3 is reduced, it is possible to determine the abnormality of the filter 3 with high accuracy. Further, by determining the abnormality of the filter 3 based on the integrated value of the PM amount flowing into the filter 3, the abnormality of the filter 3 is determined even during transient operation in which the PM amount flowing into the filter 3 can change. can do.

<Example 3>
In the present embodiment, the case described in the first embodiment and the case described in the second embodiment are considered together. Other devices and the like are the same as those in the first embodiment, and thus description thereof is omitted.

  Considering both the case of Example 1 and the case of Example 2, if the absolute value of the change amount of the PM inflow integrated value is less than the threshold, the filter 3 is normal, and if it is equal to or greater than the threshold, the filter 3 Can be said to be abnormal. This threshold value is obtained in advance by experiment or simulation as the lower limit value of the absolute value of the change amount of the PM inflow integrated value when the filter 3 is abnormal, and is stored in the ECU 10.

  That is, if the filter 3 is normal, the PM inflow amount integrated value is substantially constant regardless of the increase / decrease in the PM accumulation amount. If the filter 3 is abnormal, the PM inflow amount is increased / decreased. The integrated value changes. Therefore, it can be determined that the filter 3 is abnormal because the PM inflow integrated value has changed.

  FIG. 11 is a flowchart showing a flow of abnormality detection of the filter 3 according to the present embodiment. This routine is executed by the ECU 10 every predetermined time. In addition, about the step where the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In this embodiment, step S301 is processed after step S107. In step S301, it is determined whether or not the absolute value of a value obtained by subtracting the second PM inflow amount integrated value from the first PM inflow amount integrated value is less than a threshold value. This threshold value is obtained in advance by experiment or simulation as a lower limit value of an absolute value obtained by subtracting the second PM inflow integrated value from the first PM inflow integrated value when the filter 3 is abnormal, and is stored in the ECU 10. Keep it. The threshold value is a positive value. In this step, it is determined whether or not the absolute value of the change amount of the PM inflow amount integrated value is larger than a threshold value.

  If an affirmative determination is made in step S301, the process proceeds to step S109, and it is determined that the filter 3 is normal. On the other hand, if a negative determination is made in step S301, the process proceeds to step S110, where it is determined that the filter 3 is abnormal. In this embodiment, the ECU 10 that processes step S301 and the subsequent steps corresponds to the determination unit in the present invention.

  As described above, according to the present embodiment, the abnormality of the filter 3 can be determined with high accuracy by comparing the amount of change in the PM inflow amount integrated value with the threshold value. Further, since it is not necessary to accurately determine the amount of PM deposited on the PM sensor 4, it is difficult to be affected by variations in the detection value of the PM sensor 4. Further, even when the PM accumulation amount in the filter 3 is reduced, it is possible to determine the abnormality of the filter 3 with high accuracy. Further, in this embodiment, it is possible to determine the abnormality of the filter 3 regardless of the increase or decrease of the PM accumulation amount in the filter 3. Further, by determining the abnormality of the filter 3 based on the integrated value of the PM amount flowing into the filter 3, the abnormality of the filter 3 is determined even during transient operation in which the PM amount flowing into the filter 3 can change. can do.

<Example 4>
In Example 1-3, the abnormality of the filter 3 cannot be detected unless the PM inflow integrated value is obtained at least twice in one driving of the vehicle. For this reason, when the vehicle repeats traveling for a short time or a short distance, the abnormality of the filter 3 may not be detected because the number of PM sensor regeneration processes is insufficient.

  On the other hand, in the present embodiment, the amount of change in the PM inflow integrated value is obtained not only during one run. For this reason, the previous PM inflow amount integrated value is stored in the ECU 10, and when the PM inflow amount integrated value is obtained next time, it is compared with the stored previous PM inflow amount integrated value. Other devices and the like are the same as those in the first embodiment, and thus description thereof is omitted.

  Here, FIG. 12 is a time chart showing transitions of the vehicle speed, the PM accumulation amount in the filter 3, and the PM amount flowing into the filter 3 (PM inflow amount) according to the present embodiment. FIG. 13 is a diagram showing the relationship between the detection value of the PM sensor 4 when the filter 3 according to the present embodiment is normal and when the filter 3 is abnormal, and the integrated value of the PM amount flowing into the filter 3. It is. In FIG. 12, the PM inflow amount changes in accordance with the vehicle speed. Further, the PM accumulation amount in the filter 3 increases due to the PM discharged from the internal combustion engine 1. In FIG. 13, PM sensor regeneration processing is performed at a time point indicated by “regeneration”. In addition, the previous travel is before the “vehicle stop” and the current travel is after.

  When the detection value of the PM sensor 4 is equal to or greater than the threshold value, the PM sensor regeneration process is performed. However, in the first run, the PM sensor regeneration process is performed only once. It is only required. In the second run, the second PM inflow integrated value is obtained.

  Even in such a case, as in the first embodiment, when the filter 3 is abnormal, the PM inflow amount integrated value is smaller than when it is normal. In addition, when the filter 3 is abnormal, the PM inflow amount integrated value decreases as the PM accumulation amount in the filter 3 increases. In addition, when the filter 3 is abnormal, the period from when the detection value of the PM sensor 4 starts to increase until the threshold is reached is shorter than when the filter 3 is normal.

As described above, the PM inflow integrated value is substantially constant even when the internal combustion engine 1 is stopped once when the filter 3 is normal, but gradually decreases when the filter 3 is abnormal.

  Therefore, even if the internal combustion engine 1 is stopped, it can be determined that the filter 3 is abnormal because the PM inflow amount integrated value has decreased.

  In this embodiment, each time the PM sensor regeneration process is performed, the PM inflow amount integrated value is stored, the stored value of the previous PM inflow amount integrated value is compared with the current PM inflow amount integrated value, and PM If the amount of decrease in the inflow amount integrated value is less than the threshold value, it is determined that the filter 3 is normal, and if the amount of decrease in the PM inflow amount integrated value is equal to or greater than the threshold value, it is determined that the filter 3 is abnormal. This threshold value is obtained in advance by experiment or simulation as a lower limit value of the decrease amount of the PM inflow integrated value when the filter 3 is abnormal, and is stored in the ECU 10. Further, not only the stored value of the previous PM inflow amount integrated value but also the previous PM inflow amount integrated value obtained during the operation of the internal combustion engine 1 is compared with the current PM inflow amount integrated value. May be.

  FIG. 14 is a diagram illustrating the relationship between the amount of change in the PM inflow integrated value when the filter 3 according to the present embodiment is normal and when it is abnormal. A value obtained by subtracting the current PM inflow integrated value from the previous PM inflow integrated value is used as the amount of change in the PM inflow integrated value. If the filter 3 is normal, the change amount of the PM inflow amount integrated value is close to 0, but if the filter 3 is abnormal, the change amount of the PM inflow amount integrated value is equal to or greater than the threshold value.

  FIG. 15 is a flowchart illustrating a flow of abnormality detection of the filter 3 according to the present embodiment. This routine is executed by the ECU 10 every predetermined time. In addition, about the step where the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In this embodiment, when an affirmative determination is made in step S102, the process proceeds to step S401. In step S401, the integration of the PM inflow amount is started. Then, the process proceeds to step S104. If an affirmative determination is made in step S104, the process proceeds to step S402. In step S402, the integration of the PM inflow amount ends.

  Next, in step S403, it is determined whether or not the previous PM inflow integrated value is stored in the ECU 10. In this step, it is determined whether or not the PM inflow integrated value is stored in step S405 described later in the previous routine. If an affirmative determination is made in step S403, the process proceeds to step S404. On the other hand, if a negative determination is made, the process proceeds to step S405.

  In step S404, it is determined whether or not a value obtained by subtracting the PM inflow integrated value obtained this time from the PM inflow integrated value stored last time is less than a threshold value. This threshold value is obtained in advance through experiments or simulations as a lower limit value obtained by subtracting the PM inflow amount integrated value obtained this time from the PM inflow amount integrated value stored last time when the filter 3 is abnormal. Remember it. In this step, it is determined whether or not the decrease amount of the PM inflow amount integrated value is less than the threshold value.

  If an affirmative determination is made in step S404, the process proceeds to step S109 and it is determined that the filter 3 is normal. On the other hand, if a negative determination is made in step S404, the process proceeds to step S110, where it is determined that the filter 3 is abnormal. In this embodiment, the ECU 10 that processes step S404 and subsequent steps corresponds to the determination unit in the present invention.

In step S405, the ECU 10 stores the PM inflow amount integrated value obtained this time in the ECU 10. The PM inflow integrated value stored here is compared with the next PM inflow integrated value.

  As described above, according to the present embodiment, the abnormality of the filter 3 can be determined with high accuracy by comparing the amount of change in the PM inflow amount integrated value with the threshold value. Further, since it is not necessary to accurately determine the amount of PM deposited on the PM sensor 4, it is difficult to be affected by variations in the detection value of the PM sensor 4. Further, by determining the abnormality of the filter 3 based on the integrated value of the PM amount flowing into the filter 3, the abnormality of the filter 3 is determined even during transient operation in which the PM amount flowing into the filter 3 can change. can do.

<Example 5>
In the present embodiment, as in the fourth embodiment, when the amount of change in the PM inflow integrated value is obtained, it is obtained not only during one run. For this reason, the previous PM inflow amount integrated value is stored in the ECU 10, and when the PM inflow amount integrated value is obtained next time, it is compared with the stored previous PM inflow amount integrated value.

In the present embodiment, as in the second embodiment, the abnormality of the filter 3 is determined based on the amount of change in the PM inflow integrated value when the PM collected in the filter 3 is oxidized by NO ₂ or the like. Is detected. Other devices and the like are the same as those in the first embodiment, and thus description thereof is omitted.

Here, FIG. 16 is a time chart showing transitions of the vehicle speed, the PM accumulation amount in the filter 3, and the PM amount (PM inflow amount) flowing into the filter 3 according to the present embodiment. FIG. 17 is a diagram showing the relationship between the detected value of the PM sensor 4 when the filter 3 according to the present embodiment is normal and when the filter 3 is abnormal, and the integrated value of the PM amount flowing into the filter 3. It is. In FIG. 16, the PM inflow amount changes in accordance with the vehicle speed. Further, the amount of PM deposited on the filter 3 decreases due to oxidation by NO ₂ . In FIG. 17, PM sensor regeneration processing is performed at the time indicated by “regeneration”. In addition, the previous travel is before the “vehicle stop” and the current travel is after.

  When the detection value of the PM sensor 4 is equal to or greater than the threshold value, the PM sensor regeneration process is performed. However, in the first run, the PM sensor regeneration process is performed only once. It is only required. In the second run, the second PM inflow integrated value is obtained.

  Even in such a case, as in the second embodiment, when the filter 3 is abnormal, the PM inflow amount integrated value is smaller than when it is normal. Further, when the filter 3 is abnormal, the PM inflow integrated value increases as the PM accumulation amount in the filter 3 decreases. In addition, when the filter 3 is abnormal, the period from when the detection value of the PM sensor 4 starts to increase until the threshold is reached is shorter than when the filter 3 is normal.

  As described above, the PM inflow integrated value becomes substantially constant even when the internal combustion engine 1 is stopped once when the filter 3 is normal, but gradually increases when the filter 3 is abnormal.

  Therefore, even if the internal combustion engine 1 is stopped, it can be determined that the filter 3 is abnormal because the PM inflow integrated value has increased.

In this embodiment, the PM inflow integrated value is stored every time the PM sensor regeneration process is performed. Furthermore, the difference between the stored value of the previous PM inflow amount integrated value and the current PM inflow amount integrated value is obtained. If this difference is larger than the threshold value, it is determined that the filter 3 is normal, and this difference is less than the threshold value. If so, it is determined that the filter 3 is abnormal. This threshold is an upper limit value of the difference between the previous PM inflow amount integrated value and the current PM inflow amount integrated value when the filter 3 is abnormal,
It is obtained in advance by experiments or simulations and stored in the ECU 10. Note that the threshold according to the present embodiment is a negative value. Further, not only the stored value of the previous PM inflow amount integrated value but also the previous PM inflow amount integrated value obtained during the operation of the internal combustion engine 1 is compared with the current PM inflow amount integrated value. May be.

  FIG. 18 is a diagram illustrating the relationship between the amount of change in the PM inflow integrated value when the filter 3 according to the present embodiment is normal and when it is abnormal. A value obtained by subtracting the current PM inflow integrated value from the previous PM inflow integrated value is used as the amount of change in the PM inflow integrated value. If the filter 3 is normal, the change amount of the PM inflow amount integrated value is close to 0, but if the filter 3 is abnormal, the change amount of the PM inflow amount integrated value is equal to or less than the threshold value.

FIG. 19 is a flowchart showing a flow of abnormality detection of the filter 3 according to the present embodiment. This routine is executed by the ECU 10 every predetermined time. In addition, about the step where the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted. Further, this routine may be executed only when the amount of NO ₂ in the exhaust gas flowing into the filter is larger than a predetermined amount. That is, this routine may be executed only when the PM accumulation amount in the filter 3 is in a decreasing state.

  In this embodiment, if an affirmative determination is made in step S403, the process proceeds to step S501. In step S501, it is determined whether or not a value obtained by subtracting the PM inflow amount integrated value obtained this time from the PM inflow amount integrated value stored last time is larger than a threshold value. This threshold value is obtained in advance through experiments or simulations as an upper limit value obtained by subtracting the PM inflow amount integrated value obtained this time from the PM inflow amount integrated value stored last time when the filter 3 is abnormal. Remember it. The threshold value is a negative value. In this step, it is determined whether or not the change amount of the PM inflow amount integrated value is larger than the threshold value.

  When an affirmative determination is made in step S501, the process proceeds to step S109 and it is determined that the filter 3 is normal. On the other hand, if a negative determination is made in step S501, the process proceeds to step S110 and it is determined that the filter 3 is abnormal. In this embodiment, the ECU 10 that processes step S501 and subsequent steps corresponds to the determination unit in the present invention.

  As described above, according to the present embodiment, the abnormality of the filter 3 can be determined with high accuracy by comparing the amount of change in the PM inflow amount integrated value with the threshold value. Further, since it is not necessary to accurately determine the amount of PM deposited on the PM sensor 4, it is difficult to be affected by variations in the detection value of the PM sensor 4. Further, even when the PM accumulation amount in the filter 3 is reduced, it is possible to determine the abnormality of the filter 3 with high accuracy. Further, by determining the abnormality of the filter 3 based on the integrated value of the PM amount flowing into the filter 3, the abnormality of the filter 3 is determined even during transient operation in which the PM amount flowing into the filter 3 can change. can do.

<Example 6>
In the present embodiment, the case described in the fourth embodiment and the case described in the fifth embodiment are considered together. Other devices and the like are the same as those in the first embodiment, and thus description thereof is omitted.

  Considering both the case of the fourth embodiment and the case of the fifth embodiment, even if the change amount of the PM inflow amount integrated value is determined not only during one run, the PM inflow amount integrated value If the absolute value of the change amount is less than the threshold value, the filter 3 is normal, and if it is greater than or equal to the threshold value, it can be said that the filter 3 is abnormal. This threshold value is obtained in advance by experiment or simulation as the lower limit value of the absolute value of the change amount of the PM inflow integrated value when the filter 3 is abnormal, and is stored in the ECU 10.

  That is, when the amount of change in the PM inflow integrated value is obtained not only during one run, but if the filter 3 is normal, the PM inflow does not depend on the increase or decrease in the amount of accumulated PM. Although the integrated value is substantially constant, if the filter 3 is abnormal, the PM inflow amount integrated value changes due to the increase or decrease of the PM accumulation amount. Therefore, it can be determined that the filter 3 is abnormal because the PM inflow integrated value has changed.

  FIG. 20 is a flowchart illustrating a flow of abnormality detection of the filter 3 according to the present embodiment. This routine is executed by the ECU 10 every predetermined time. In addition, about the step where the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In this embodiment, if an affirmative determination is made in step S403, the process proceeds to step S601. In step S601, it is determined whether or not the absolute value of a value obtained by subtracting the PM inflow amount integrated value obtained this time from the PM inflow amount integrated value stored last time is less than a threshold value. This threshold value is set as a lower limit value of an absolute value of a value obtained by subtracting the PM inflow amount integrated value obtained this time from the PM inflow amount integrated value stored last time when the filter 3 is abnormal. Obtained and stored in the ECU 10. The threshold value is a positive value. In this step, it is determined whether or not the absolute value of the change amount of the PM inflow amount integrated value is less than a threshold value.

  When an affirmative determination is made in step S601, the process proceeds to step S109, and it is determined that the filter 3 is normal. On the other hand, if a negative determination is made in step S601, the process proceeds to step S110 and it is determined that the filter 3 is abnormal. In this embodiment, the ECU 10 that processes step S601 and subsequent steps corresponds to the determination unit in the present invention.

  As described above, according to the present embodiment, the abnormality of the filter 3 can be determined with high accuracy by comparing the amount of change in the PM inflow amount integrated value with the threshold value. Further, since it is not necessary to accurately determine the amount of PM deposited on the PM sensor 4, it is difficult to be affected by variations in the detection value of the PM sensor 4. Further, even when the PM accumulation amount in the filter 3 is reduced, it is possible to determine the abnormality of the filter 3 with high accuracy. Further, in this embodiment, it is possible to determine the abnormality of the filter 3 regardless of the increase or decrease of the PM accumulation amount in the filter 3. Further, by determining the abnormality of the filter 3 based on the integrated value of the PM amount flowing into the filter 3, the abnormality of the filter 3 is determined even during transient operation in which the PM amount flowing into the filter 3 can change. can do.

1 Internal combustion engine 2 Exhaust passage 3 Filter 4 PM sensor 5 PM sensor 10 ECU
11 Accelerator pedal 12 Accelerator opening sensor 13 Crank position sensor 14 Differential pressure sensor

Claims (3)

A filter provided in an exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust;
A PM sensor for detecting the amount of particulate matter in the exhaust gas downstream of the filter;
A filter inflow PM amount detection device that detects or estimates the amount of particulate matter in the exhaust gas upstream of the filter;
In the filter abnormality detection device comprising:
A PM sensor regeneration unit that performs a PM sensor regeneration process, which is a process of removing particulate matter from the PM sensor when the amount of particulate matter deposited on the PM sensor exceeds a predetermined amount;
The integrated value of the amount of particulate matter detected or estimated by the filter inflow PM amount detection device from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started, and a reference value A determination unit that determines that the filter is abnormal when the difference is equal to or greater than a threshold;
An abnormality detection device for a filter comprising: When the amount of NO ₂ in the exhaust gas flowing into the filter is greater than a predetermined amount, the determination unit is configured to perform the PM sensor regeneration process from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started. Claim that when the value obtained by subtracting the integrated value of the amount of particulate matter detected or estimated by the filter inflow PM amount detection device from the reference value is equal to or less than a negative threshold value, the filter is determined to be abnormal. Item 6. The filter abnormality detection device according to Item 1.   The determination unit determines the reference value of the particulate matter detected or estimated by the filter inflow PM amount detection device from the time when the PM sensor regeneration process is completed to the time when the next PM sensor regeneration process is started. The filter abnormality detection device according to claim 1 or 2, wherein the filter is an integrated value of the amount, and is an integrated value of the amount of particulate matter detected or estimated last time.

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