JP2009103043A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of determining abnormality when the abnormality is generated in a filter even if a degree of the abnormality is small. <P>SOLUTION: The exhaust emission control device of the engine 1 estimates a deposition amount of PM depositing on the filter 35 provided on an exhaust passage 33 for collecting the PM in exhaust gas, based on an engine operation status. When the estimated value Ax becomes equal to or higher than a predetermined determination value AS for executing regeneration processing, the device executes the regeneration processing of raising temperature of the filter 35 to a predetermined temperature or higher, burning the PM, and removing the PM from the filter 35. Differential pressure between pressure on an exhaust upstream side and pressure on an exhaust downstream side of the filter 35 is detected by a differential pressure sensor 64. When the differential pressure ΔPS when the estimated value Ax of the PM deposition amount is equal to or higher than the regeneration processing execution determination value AS becomes equal to or lower than a predetermined threshold value R, the device determines that the filter 35 has abnormality. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine in which a filter is provided in an exhaust passage of the internal combustion engine so as to collect particulate matter in the exhaust gas.

  Conventionally, as an exhaust emission control device for this type of internal combustion engine, for example, the one described in Patent Document 1 is known. In conventional exhaust gas purification apparatuses for internal combustion engines, including those described in Patent Document 1, a filter for collecting particulate matter (PM) in the exhaust gas is provided in the exhaust passage, Thereby, the amount of PM discharged to the outside is reduced. In such an exhaust purification device, as the amount of accumulated PM collected by the filter increases, the exhaust pressure on the upstream side of the filter, that is, the back pressure rises, causing a problem such as deterioration of fuel consumption. Therefore, the PM accumulation amount is estimated based on the engine operation state such as the fuel injection amount, and when the estimated value of the PM accumulation amount exceeds a predetermined value, the PM is burned and removed from the filter. I try to play it. Specifically, for example, an unburned fuel component is supplied to a filter carrying an oxidation catalyst, the unburned fuel component is oxidized in the exhaust or on the catalyst, and the oxidation catalyst is activated by the heat generated thereby. To promote the combustion of PM.

  By the way, for example, if the filter is regenerated in a state where the amount of accumulated PM is excessively large, the heat generated when the PM burns may become too large, and the filter may be melted. In addition, cracks may occur due to stress concentration on a part of the filter. When an abnormality occurs in the filter in this way, a part of the PM that should be collected by the filter is discharged to the outside through the damaged part of the filter.

Therefore, conventionally, in order to detect such a filter abnormality, the differential pressure immediately after the regeneration of the filter is completed is detected by a differential pressure sensor that detects the differential pressure between the pressure upstream of the exhaust of the filter and the pressure downstream of the exhaust. When the differential pressure becomes a predetermined threshold value or less, it is determined that an abnormality has occurred in the filter. This is because when there is an abnormality in the filter, that is, when there is a space in the filter that connects the exhaust upstream side of the filter and the exhaust downstream side due to melting damage or the like, the filter abnormality occurs. Since the flow rate of the exhaust gas flowing out from the upstream side of the filter to the downstream side of the exhaust through such a communication space increases compared with the case where the pressure is not, the differential pressure between the pressure on the upstream side of the filter and the pressure on the downstream side of the exhaust is small. It pays attention to becoming.
JP-A-6-323127

  By the way, in the conventional exhaust purification device, when the degree of abnormality of the filter is large, for example, when most of the filter is melted, it is certainly determined that the abnormality has occurred in the filter. Can do. However, when the degree of abnormality of the filter is small, for example, when melting damage occurs only in a part of the filter, the flow rate of the exhaust gas flowing from the upstream side of the filter to the downstream side of the exhaust through the damaged part of the filter is not so much. Since the pressure does not increase, the differential pressure between the pressure on the upstream side of the filter and the pressure on the downstream side of the exhaust gas hardly decreases as compared with the case where no abnormality occurs in the filter. For this reason, in the conventional exhaust purification apparatus that determines that an abnormality has occurred in the filter when the differential pressure immediately after the regeneration of the filter has become equal to or less than a predetermined threshold value, the abnormality has occurred in the filter. Even when the level of the abnormality is small, there is a problem that this cannot be detected.

  The present invention has been made in view of such circumstances, and an object of the present invention is to purify exhaust gas of an internal combustion engine that can determine even when the degree of abnormality is small when abnormality occurs in the filter. To provide an apparatus.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a filter provided in an exhaust passage of an internal combustion engine for collecting particulate matter in the exhaust, and an amount of particulate matter deposited on the filter based on an engine operating state. An estimation means for estimating the accumulated amount of particulate matter, and when the estimated amount of accumulated particulate matter is equal to or higher than a predetermined regeneration processing execution determination value, the temperature of the filter is increased to a predetermined temperature or more to burn the particulate matter. In the exhaust gas purification apparatus for an internal combustion engine having a regeneration process control means for executing a regeneration process to be removed from the filter, a differential pressure for detecting a differential pressure between the pressure upstream of the exhaust of the filter and the pressure downstream of the exhaust An abnormality that determines that the filter has an abnormality when the differential pressure when the accumulated amount estimated value of the particulate matter estimated by the estimation unit and the estimation unit is equal to or greater than a predetermined value is equal to or less than a predetermined threshold value Judge Further comprising bets as its gist.

  When damage such as erosion or cracking occurs in the filter, the exhaust upstream of the filter flows into the exhaust downstream of the filter through the damaged part. Therefore, the pressure upstream of the filter and the downstream of the exhaust The differential pressure ΔP1 with respect to the pressure on the side is smaller than the differential pressure ΔP2 when such an abnormality does not occur. However, when the amount of the particulate matter deposited on the filter is small, the exhaust gas easily passes through the portion other than the damaged portion of the filter, so that the difference between the differential pressures ΔP1 and ΔP2 is relatively small. . On the other hand, when the amount of the particulate matter deposited on the filter is large, the flow passage resistance when the exhaust gas passes through a portion other than the damaged portion of the filter is increased by the deposited particulate matter. The difference between the differential pressures ΔP1 and ΔP2 is relatively large.

  Focusing on this point, in the above configuration, when the estimated amount of particulate matter accumulated by the estimating means is greater than or equal to a predetermined value, that is, the amount of particulate matter deposited on the filter is large, the above-described differential pressure When the difference between ΔP1 and ΔP2 becomes relatively large, it is determined that there is an abnormality in the filter on the condition that the differential pressure at that time is equal to or less than a predetermined threshold value. As a result, when an abnormality occurs in the filter, it can be determined even when the degree of the abnormality is small.

  According to a second aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the first aspect, the abnormality determining means determines that the estimated accumulation amount of the particulate matter estimated by the estimating means is the execution of the regeneration process. The gist is to perform abnormality determination based on the differential pressure when the value is equal to or greater than the value.

  In the exhaust gas purification apparatus for an internal combustion engine, when the regeneration process is stopped, the amount of particulate matter accumulated increases until the next regeneration process is performed. The differential pressure from the pressure increases. In addition, when the regeneration process is executed, the amount of particulate matter deposited decreases until the regeneration process is stopped next time, and thus the above-described differential pressure decreases. For this reason, the differential pressure described above when the estimated amount of particulate matter accumulated estimated by the estimation means is equal to or greater than the regeneration process execution determination value is the next regeneration process stopped after the regeneration process was last stopped. It becomes the maximum value in the period until it reaches or a value in the vicinity thereof.

  Paying attention to this point, in the above configuration, when the estimated amount of particulate matter estimated by the estimating means is equal to or greater than the regeneration processing execution determination value, that is, the amount of particulate matter deposited on the filter is at or near the maximum. Therefore, when the difference between the above-described differential pressures ΔP1 and ΔP2 is maximized or close to it, the abnormality determination is performed based on the differential pressure. As a result, the abnormality determination can be performed with higher accuracy.

  According to a third aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the first aspect, the abnormality determining means monitors the differential pressure, and the amount of particulate matter deposited estimated by the estimating means The gist of performing abnormality determination based on the maximum value of the differential pressure in a period from when the estimated value becomes equal to or greater than the regeneration process execution determination value and when the regeneration process is started until the regeneration process is stopped. To do.

  When the amount of particulate matter deposited on the filter is estimated based on the engine operating condition, the estimated amount of accumulation is the maximum when the regeneration processing execution judgment value is reached, that is, at the start of the regeneration processing. It becomes. On the other hand, the actual deposition amount of the particulate matter may change with a delay with respect to the start timing of such regeneration processing.

  Focusing on this point, in the above configuration, the differential pressure is monitored, and the accumulated amount estimated value of the particulate matter estimated by the estimation means is equal to or higher than the regeneration processing execution determination value, and the regeneration processing is started. The abnormality determination is performed based on the maximum value of the differential pressure during the period until the regeneration process is stopped. As a result, even when the actual amount of particulate matter deposited changes with a delay with respect to the start timing of such regeneration processing, abnormality determination can be performed with higher accuracy.

  According to a fourth aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to any one of the first to third aspects, the intake air amount when the differential pressure is detected in the abnormality determination by the abnormality determination means is The gist of the invention is that it further includes a threshold value setting means for setting the threshold value to a larger value when the intake air amount is larger than when the intake air amount is small.

  When the intake air amount is large, the flow rate of the exhaust gas is larger than when the intake air amount is small, so that the differential pressure between the pressure on the exhaust upstream side of the filter and the pressure on the downstream side of the exhaust gas becomes large. For this reason, when the abnormality is determined, if the threshold value used for the abnormality determination is set without considering the relationship between the intake air amount and the above-described differential pressure, for example, the following problem may occur. That is, when the abnormality is determined, if the threshold value is set to a relatively large value even though the intake amount at that time is small, the above-described differential pressure is set to a predetermined value even when no abnormality occurs in the filter. There is a possibility that an erroneous determination is made that an abnormality has occurred in the filter because the threshold value is not exceeded.

  In this regard, according to the above configuration, when determining the abnormality, the threshold value is set to a larger value when the intake air amount when the differential pressure is detected is larger than when the intake air amount is small. In other words, a threshold value used for abnormality determination is set in accordance with the relationship between the intake air amount and the above-described differential pressure. As a result, it is possible to avoid an erroneous determination that an abnormality has occurred in the filter.

  According to a fifth aspect of the present invention, in the exhaust gas purification device for an internal combustion engine according to any one of the first to fourth aspects, an exhaust gas temperature detecting means for detecting a temperature of the exhaust gas flowing into the filter, and the abnormality determination In the abnormality determination by the means, the regeneration process is a period from when the regeneration process was last stopped until the differential pressure is detected when the particulate matter accumulation amount estimated value is greater than or equal to the predetermined value. And a threshold value setting means for calculating an integral value of the exhaust temperature during a period when the engine is stopped and setting the threshold value to a smaller value when the calculated integral value is larger than when the integral value is small. Is the gist.

  The period during which the regeneration process is stopped differs from the period during which the regeneration process is being executed, and the exhaust temperature varies greatly depending on the engine operating state at that time, for example, when the exhaust temperature is high for a long time. Thus, when the integrated value of the exhaust temperature is large, the oxidation of the particulate matter deposited on the filter is promoted more than usual. As a result, the amount of particulate matter actually deposited on the filter is less than the amount estimated by the estimation means, and the upstream side pressure of the filter when the estimated amount of accumulation exceeds a predetermined value. And the pressure downstream of the exhaust gas are small. Therefore, when the oxidation of the particulate matter is promoted in this way, even if no abnormality occurs in the filter, the above-described differential pressure becomes equal to or less than the threshold value, and the filter is abnormal. May be misjudged.

  In this regard, according to the above-described configuration, in the abnormality determination, the period from when the regeneration process is last stopped until the above-described differential pressure is detected when the estimated amount of accumulated particulate matter is equal to or greater than a predetermined value. When the integral value of the exhaust gas temperature during the period when the regeneration process is stopped is large, the threshold value is set to a smaller value than when the integral value of the exhaust gas temperature is small. In other words, the threshold used for abnormality determination is set in accordance with the degree of oxidation promotion of the particulate matter. As a result, it is possible to avoid an erroneous determination that an abnormality has occurred in the filter.

  According to a sixth aspect of the present invention, there is provided a filter provided in an exhaust passage of an internal combustion engine for collecting particulate matter in the exhaust, and an accumulation amount of particulate matter deposited on the filter based on an engine operating state. An estimation means for estimating the accumulated amount of particulate matter, and when the estimated amount of accumulated particulate matter is equal to or higher than a predetermined regeneration processing execution determination value, the temperature of the filter is increased to a predetermined temperature or more to burn the particulate matter. The regeneration process to remove from the filter is executed, and when the regeneration process is being executed, the particulate matter accumulation amount estimated value is equal to or less than a predetermined regeneration process stop judgment value smaller than the regeneration process execution judgment value. In the exhaust gas purification apparatus for an internal combustion engine, which includes a regeneration process control means for sometimes stopping the regeneration process, a differential pressure detecting means for detecting a differential pressure between the pressure on the exhaust upstream side of the filter and the pressure on the downstream side of the exhaust gas And before The differential pressure when the accumulation amount estimated value of the particulate matter estimated by the estimation means is greater than or equal to a first predetermined value, and the second predetermined value where the accumulation amount estimated value is smaller than the first predetermined value. The gist of the present invention is to include an abnormality determining means that compares the differential pressure when the difference is below, and determines that the filter is abnormal when the degree of divergence between the differential pressures is equal to or less than a predetermined threshold. .

  The flow resistance when the exhaust gas passes through the filter varies from filter to filter due to individual differences. In this case, the differential pressure ΔP1 when there is no abnormality in the filter and the differential pressure ΔP2 when there is an abnormality in the filter deviate from the values when the filter is assumed to be standard. . That is, in the case of a filter whose flow resistance is larger than that of a standard filter, for example, the differential pressures ΔP1 and ΔP2 are larger than the standard differential pressures ΔP1 and ΔP2. For this reason, there is a concern that the reliability of the abnormality determination is lowered due to the influence of the individual differences of the filters.

  Focusing on this point, in the above-described configuration, the differential pressure when the estimated amount of particulate matter estimated by the estimating means is equal to or greater than the first predetermined value and the estimated amount of deposit are more than the first predetermined value. Are compared with the differential pressure when the difference is less than the second predetermined value, and when the degree of divergence between these differential pressures is less than or equal to a predetermined threshold, it is determined that there is an abnormality in the filter. As a result, even if each differential pressure shows a different value from the standard filter due to individual differences in the filter, the effect of such individual differences is offset by detecting the degree of divergence between the differential pressures. Therefore, when an abnormality occurs in the filter, it can be determined with higher accuracy.

  According to a seventh aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the sixth aspect, the abnormality determining means determines that the estimated accumulation amount of the particulate matter estimated by the estimating means is the execution of the regeneration process. The gist is that abnormality determination is performed based on the differential pressure when the value is equal to or greater than the value and the differential pressure when the estimated accumulation amount is equal to or less than the regeneration process stop determination value.

  The above-mentioned differential pressure when the estimated amount of particulate matter accumulated estimated by the estimation means is equal to or greater than the regeneration process execution determination value is from when the regeneration process was last stopped until the next regeneration process is stopped. It becomes the maximum value in the period of or the value near it. In addition, the above-described differential pressure when the estimated amount of particulate matter accumulated estimated by the estimating means is equal to or less than the regeneration process stop determination value is the next regeneration process started from when the regeneration process was last started. It becomes the minimum value in the period until it reaches or a value in the vicinity thereof.

  Focusing on this point, in the above-described configuration, the differential pressure when the estimated accumulation amount of the particulate matter estimated by the estimation means is equal to or greater than the regeneration process execution determination value and the estimated accumulation amount are determined as the regeneration process stop determination. The abnormality determination is performed based on the differential pressure when the difference is equal to or less than the value, that is, based on the maximum value of the difference degree of the differential pressure or a value close thereto. As a result, the abnormality determination can be performed with higher accuracy.

  According to an eighth aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the sixth aspect, the abnormality determining means monitors the differential pressure, and accumulates the particulate matter estimated by the estimating means. The maximum value of the differential pressure in the period from when the estimated value becomes equal to or higher than the regeneration process execution determination value to the next time equal to or smaller than the regeneration process stop determination value, and the accumulation amount estimated value is equal to or less than the regeneration process stop determination value The gist of the present invention is that abnormality determination is performed based on the minimum value of the differential pressure in a period from the time when the value becomes equal to or higher than the regeneration processing execution determination value.

  When the amount of particulate matter deposited on the filter is estimated based on the engine operating condition, the estimated amount of accumulation is the maximum when the regeneration processing execution judgment value is reached, that is, at the start of the regeneration processing. After that, when the reproduction process stop determination value is reached, that is, at the end of the reproduction process, it becomes the minimum. On the other hand, the actual deposition amount of the particulate matter may change with a delay with respect to the start / end timing of such regeneration processing.

  Focusing on this point, in the above configuration, the differential pressure is monitored, and the particulate matter accumulation amount estimated value estimated by the estimation means becomes equal to or greater than the regeneration processing execution determination value, and then the regeneration processing stop determination value is reached. The maximum value of the differential pressure in the period until the following and the minimum value of the differential pressure in the period until the accumulated amount estimated value becomes less than the regeneration process stop judgment value and then becomes the regeneration process execution judgment value or more Based on the above, abnormality determination is performed. As a result, even when the actual amount of particulate matter deposited changes with a delay with respect to the start / end timing of such regeneration processing, the abnormality determination can be performed with higher accuracy.

  The invention according to claim 9 is the exhaust gas purification apparatus for an internal combustion engine according to any one of claims 6 to 8, wherein the exhaust gas temperature detecting means for detecting the temperature of the exhaust gas flowing into the filter, and the abnormality determination In the abnormality determination by the means, a period from when the regeneration process is last stopped until the differential pressure is detected when the estimated amount of particulate matter accumulated is greater than or equal to the first predetermined value. A threshold value setting means for calculating an integral value of the exhaust gas temperature during a period when the regeneration process is stopped, and setting the threshold value to a smaller value when the calculated integral value is larger than when the integral value is small; The gist is to provide further.

  The period during which the regeneration process is stopped differs from the period during which the regeneration process is being executed, and the exhaust temperature varies greatly depending on the engine operating state at that time, for example, when the exhaust temperature is high for a long time. Thus, when the integrated value of the exhaust temperature is large, the oxidation of the particulate matter deposited on the filter is promoted more than usual. As a result, the amount of particulate matter actually deposited on the filter is less than the amount estimated by the estimating means, and the exhaust of the filter when the estimated amount of deposit is equal to or greater than the first predetermined value. The differential pressure between the upstream pressure and the pressure downstream of the exhaust gas is small. Therefore, when the oxidation of the particulate matter is promoted in this way, even if no abnormality occurs in the filter, the above-described differential pressure becomes equal to or less than the threshold value, and the filter is abnormal. May be misjudged.

  In this regard, according to the above-described configuration, in the abnormality determination, the period from when the regeneration process is last stopped until the differential pressure when the particulate matter accumulation amount estimated value is equal to or greater than the first predetermined value is detected. When the integral value of the exhaust temperature during the period when the regeneration process is stopped is large, the threshold value is set to a smaller value than when the integral value of the exhaust temperature is small. In other words, the threshold used for abnormality determination is set in accordance with the degree of oxidation promotion of the particulate matter. As a result, it is possible to avoid an erroneous determination that an abnormality has occurred in the filter.

  According to a tenth aspect of the present invention, there is provided a filter provided in an exhaust passage of an internal combustion engine for collecting particulate matter in the exhaust, and an accumulation amount of the particulate matter deposited on the filter based on an engine operating state. An estimation means for estimating the accumulated amount of particulate matter, and when the estimated amount of accumulated particulate matter is equal to or higher than a predetermined regeneration processing execution determination value, the temperature of the filter is increased to a predetermined temperature or more to burn the particulate matter. In the exhaust gas purification apparatus for an internal combustion engine having a regeneration process control means for executing a regeneration process to be removed from the filter, a differential pressure for detecting a differential pressure between the pressure upstream of the exhaust of the filter and the pressure downstream of the exhaust The latest value of the differential pressure when the estimation amount of the particulate matter estimated by the estimation unit and the estimation unit is equal to or greater than a predetermined value is compared with the past value, and the divergence degree of these differential pressures is predetermined. Over the threshold of As its gist in that it comprises an abnormality determination means for determining that there is an abnormality in the filter when the.

  According to the above configuration, the latest value of the differential pressure when the estimated amount of particulate matter accumulated estimated by the estimating means is equal to or greater than a predetermined value is compared with the past value, and the difference between these differential pressures is predetermined. It is determined that there is an abnormality in the filter when the threshold is exceeded. Thereby, in addition to the effect of the invention according to claim 1, even when the flow path resistance differs for each filter due to individual differences of the filters, when the abnormality occurs in the filters, this is more accurately performed. It becomes possible to judge. That is, the same effect as that of the invention according to claim 6 can be obtained.

  According to an eleventh aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the tenth aspect, the abnormality determining means determines that the estimated accumulation amount of the particulate matter estimated by the estimating means is the execution of the regeneration process. The gist is that abnormality determination is performed based on the latest value of the differential pressure and the past value when the value is equal to or greater than the value.

According to this configuration, in addition to the effect of the invention according to the tenth aspect, the same effect as the effect of the invention according to the seventh aspect can be achieved.
According to a twelfth aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the tenth aspect, the abnormality determination unit monitors the differential pressure and also accumulates the particulate matter estimated by the estimation unit. Abnormality based on the latest value and the past value of the maximum value of the differential pressure in the period from the start of the regeneration process when the estimated value is equal to or greater than the regeneration process execution determination value until the regeneration process is stopped The gist is to make the determination.

According to this configuration, in addition to the effect of the invention according to the tenth aspect, the same effect as the effect of the invention according to the eighth aspect can be achieved.
According to a thirteenth aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to any one of the tenth to twelfth aspects, when the abnormality determination is performed by the abnormality determination means, the latest value of the differential pressure is detected. The gist of the invention is that it includes a threshold value setting means for setting the threshold value to a smaller value when the intake amount is large than when the intake amount is small.

  When the intake air amount is large, the flow rate of the exhaust gas is larger than when the intake air amount is small, so that the differential pressure between the pressure on the exhaust upstream side of the filter and the pressure on the downstream side of the exhaust gas becomes large. For this reason, when the abnormality is determined, if the threshold value used for the abnormality determination is set without considering the relationship between the intake air amount and the above-described differential pressure, for example, the following problem may occur. That is, when the abnormality is determined, if the threshold value is set to a relatively small value even though the intake amount when the latest value of the differential pressure is detected is small, even if the filter is not abnormal. There is a concern that the degree of divergence between the latest value of the differential pressure and the past value becomes equal to or less than a predetermined threshold value, and an erroneous determination is made that an abnormality has occurred in the filter.

  In this regard, according to the above configuration, when the abnormality is determined, the threshold value is set to a smaller value when the intake amount when the latest value of the differential pressure is detected is larger than when the intake amount is small. In other words, a threshold value used for abnormality determination is set in accordance with the relationship between the intake air amount and the above-described differential pressure. As a result, it is possible to avoid an erroneous determination that an abnormality has occurred in the filter.

  According to a fourteenth aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to any one of the tenth to thirteenth aspects, an exhaust gas temperature detecting means for detecting a temperature of the exhaust gas flowing into the filter, and the abnormality determination In the abnormality determination by the means, the period from when the regeneration process was last stopped until the latest value of the differential pressure when the estimated amount of particulate matter deposition amount is equal to or greater than the predetermined value is detected. A threshold value setting means for calculating an integral value of the exhaust temperature during a period when the regeneration process is stopped and setting the threshold value to a larger value when the calculated integral value is larger than when the integral value is small; The gist is to provide further.

  The period during which the regeneration process is stopped differs from the period during which the regeneration process is being executed, and the exhaust temperature varies greatly depending on the engine operating state at that time, for example, when the exhaust temperature is high for a long time. Thus, when the integrated value of the exhaust temperature is large, the oxidation of the particulate matter deposited on the filter is promoted more than usual. As a result, the amount of particulate matter actually deposited on the filter is less than the amount estimated by the estimation means, and the upstream side pressure of the filter when the estimated amount of accumulation exceeds a predetermined value. The latest value of the differential pressure between the pressure and the pressure downstream of the exhaust gas is small. Therefore, when the oxidation of the particulate matter is promoted in this way, the degree of deviation between the latest value of the differential pressure and its past value is equal to or greater than the threshold value even when no abnormality occurs in the filter. Therefore, there is a possibility that an erroneous determination that an abnormality has occurred in the filter is made.

  In this regard, according to the above-described configuration, when abnormality is determined, the period from when the regeneration process is last stopped until the latest value of the differential pressure when the estimated amount of particulate matter accumulation is greater than or equal to a predetermined value is detected. When the integrated value of the exhaust temperature during the period when the regeneration process is stopped is large, the threshold value is set to a larger value than when the integrated value of the exhaust temperature is small. In other words, the threshold used for abnormality determination is set in accordance with the degree of oxidation promotion of the particulate matter. As a result, it is possible to avoid an erroneous determination that an abnormality has occurred in the filter.

<First Embodiment>
Hereinafter, a first embodiment in which the present invention is applied to an exhaust emission control device for an in-vehicle diesel engine will be described with reference to FIGS.

FIG. 1 is a block diagram showing a diesel engine equipped with an exhaust emission control device according to this embodiment and its peripheral configuration.
The engine 1 includes a plurality of cylinders #N (N = 1 to 4) and a plurality of fuel injection valves 41 for injecting and supplying high-pressure fuel to the combustion chambers 5 of the respective cylinders #N. It has been. An intake port 21 for introducing outside air into each combustion chamber 5 and an exhaust port 31 for discharging combustion gas generated in each combustion chamber 5 are connected to each cylinder #N.

  The intake port 21 is provided with an intake valve 22 for opening and closing the intake port 21. An intake passage 23 is connected to the intake port 21 via an intake manifold. The intake passage 23 is provided with a throttle valve 24 for metering intake air. The throttle valve 24 is driven to open and close by a motor 25.

  The exhaust port 31 is provided with an exhaust valve 32 for opening and closing the exhaust port 31. An exhaust passage 33 is connected to the exhaust port 31 via an exhaust manifold. The exhaust passage 33 is provided with a catalytic converter 34 for purifying exhaust. Inside the catalytic converter 34, a filter 35 for collecting PM in the exhaust gas is provided. The filter 35 is formed of a porous material, and an oxidation catalyst that oxidizes and purifies hydrocarbon (HC) and carbon monoxide (CO) in exhaust gas is supported on the surface of the filter 35. Due to the reaction triggered by the oxidation catalyst, PM deposited on the filter 35 is burned (oxidized) and removed from the filter 35. A fuel addition valve 42 for injecting low-pressure fuel and supplying it to the filter 35 is attached to the exhaust passage 33.

  The engine 1 is provided with various sensors for detecting the engine operating state. For example, the mass flow rate of air flowing into the combustion chamber 5 (hereinafter referred to as the intake air amount GA) is detected by the air flow meter 61 provided in the intake passage 23. Further, the opening degree of the throttle valve 24 (throttle opening degree TA) is detected by a throttle opening degree sensor 62 provided in the motor 25 that opens and closes the throttle valve 24. Further, the exhaust gas temperature sensor 63 provided on the exhaust gas upstream side of the filter 35 in the exhaust passage 33 detects the temperature Te of the exhaust gas flowing into the filter 35 (hereinafter referred to as the exhaust gas temperature Te). A differential pressure sensor 64 provided in the exhaust passage 33 detects a differential pressure ΔP (hereinafter abbreviated as differential pressure ΔP) between the exhaust upstream side of the filter 35 and the exhaust downstream side thereof. The differential pressure sensor 64 corresponds to the differential pressure detection means according to the present invention, and the exhaust temperature sensor 63 corresponds to the exhaust temperature detection means according to the present invention.

  Outputs of these various sensors are input to the electronic control unit 7. The electronic control unit 7 includes a central processing control unit (CPU), a read only memory (ROM) that stores various programs and maps in advance, a random access memory (RAM) that temporarily stores calculation results of the CPU, a timer counter, The microcomputer is mainly configured with an input interface, an output interface, and the like.

  The electronic control unit 7 performs various controls of the engine 1 such as fuel injection amount control of the fuel injection valve 41, fuel injection timing control, throttle valve 24 opening control, and the like. The electronic control unit 7 also performs regeneration processing control for regenerating the function of the filter 35 by burning PM removed from the filter 35 and removing it from the filter 35. The electronic control device 7 corresponds to the reproduction processing control means according to the present invention.

  In this regeneration processing, the amount of PM deposited on the filter 35 is estimated based on the engine operating state, and when the estimated value Ax of this PM deposition amount becomes equal to or greater than a predetermined regeneration processing execution determination value AS. The fuel is injected from the fuel addition valve 42 into the exhaust passage 33 and the fuel is supplied to the filter 35. Thus, the catalyst bed temperature of the filter 35 is raised to a predetermined temperature, whereby PM is combusted (oxidized) and removed from the filter 35. Further, when the regeneration process is being performed, the regeneration process is stopped when the estimated value Ax of the PM accumulation amount becomes equal to or less than a predetermined regeneration process stop determination value AE that is smaller than the regeneration process execution determination value AS. I have to. Note that the regeneration process execution determination value AS and the regeneration process stop determination value AE are determined based on experiments or the like.

Here, the calculation process of the estimated value Ax of the PM accumulation amount executed through the electronic control unit 7 will be described.
First, when the regeneration process is not executed, the estimated value Ax of the PM accumulation amount is calculated by (Equation 1).

(Formula 1)
Ax = Axold + Ainc
The previous estimated value Axold on the right side is the estimated value Ax of the PM accumulation amount calculated in the previous control cycle. The estimated value increase amount Ainc corresponds to the amount of PM accumulated on the filter 35 during the period from the previous control cycle to the current control cycle. This estimated value increase amount Ainc is calculated based on the fuel injection amount from the fuel injection valve 41 and the fuel addition amount from the fuel addition valve 42. Incidentally, the estimated value increase amount Ainc increases as the fuel injection amount from the fuel injection valve 41 increases and as the fuel addition amount from the fuel addition valve 42 increases. When the regeneration process is not executed, the estimated value increase amount Ainc is normally calculated assuming that the fuel addition amount of the fuel addition valve 42 is “0”.

Next, when the regeneration process is being performed, the estimated value Ax of the PM accumulation amount is calculated by (Equation 2).
(Formula 2)
Ax = Axold + Ainc-Adec
The previous estimated value Axold and estimated value increase Ainc on the right side are the same as in the above (Equation 1). Further, the estimated value decrease amount Adec corresponds to the amount of PM removed from the filter 35 in the period from the previous control cycle to the current control cycle. This estimated value reduction amount Adec is calculated based on the exhaust temperature Te, in other words, the catalyst bed temperature of the filter 35. Incidentally, the estimated value decrease amount Adec tends to increase as the exhaust gas temperature Te increases. When the regeneration process is being executed, the estimated value decrease amount Adec becomes larger than the estimated value increase amount Ainc (Adec> Ainc), and the PM deposition amount estimated value Ax decreases. The electronic control unit 7 corresponds to the estimation means according to the present invention, and the PM deposition amount estimated value Ax corresponds to the deposition amount estimated value according to the present invention.

  By the way, for example, if the regeneration of the filter 35 is performed in a state where the amount of accumulated PM is excessively large, the filter 35 may be melted due to excessive heat generated when the PM burns. In addition, cracks may occur due to stress concentration on a part of the filter 35. When an abnormality occurs in the filter 35 in this way, a part of the PM that should be collected by the filter 35 is discharged to the outside through the damaged portion of the filter 35.

  Here, the relationship between the actual value B of the PM accumulation amount and the differential pressure ΔP will be described with reference to the graph of FIG. In the figure, the relationship when the filter 35 is not damaged is indicated by a solid line, and the relationship when the filter 35 is damaged is indicated by a one-dot chain line.

  As described above, when damage such as melting or cracking occurs in the filter 35, the exhaust gas upstream of the filter 35 flows into the exhaust gas downstream side of the filter 35 through the damaged portion. As shown, the differential pressure ΔP1 is smaller than the differential pressure ΔP2 when such an abnormality does not occur. However, when the actual value B of the PM accumulation amount is small, the exhaust gas easily passes through the portion other than the damaged portion of the filter 35, and therefore the difference between these differential pressures ΔP1 and ΔP2 is relatively small. On the other hand, when the actual value B of the PM accumulation amount is large, the flow path resistance when the exhaust gas passes through the portion other than the damaged portion of the filter 35 increases due to the accumulated PM, and thus the above-described differential pressure ΔP1. , ΔP2 is relatively large.

  Focusing on this point, in this embodiment, it is determined that there is an abnormality in the filter 35 when the differential pressure ΔP when the estimated value Ax of the PM accumulation amount is equal to or greater than a predetermined value is equal to or less than a predetermined threshold R. I am doing so. In this embodiment, the predetermined value is set to the reproduction process execution determination value AS, which is the reproduction process execution condition. The electronic control unit 7 corresponds to an abnormality determination unit and a threshold setting unit according to the present invention.

Here, the relationship between the intake air amount GA and the differential pressure ΔP will be described with reference to the graph of FIG.
As shown in FIG. 3, when the intake air amount GA is large, the flow rate of the exhaust gas discharged from the combustion chamber 5 is larger than when the intake air amount GA is small, so that the differential pressure ΔP is also large. For this reason, when the threshold value R used for the abnormality determination is set without considering the relationship between the intake air amount GA and the differential pressure ΔP in the abnormality determination, for example, the following problem may occur. That is, when the abnormality is determined, if the threshold value R is set to a relatively large value in spite of the small intake air amount GA at that time, the differential pressure ΔP is increased even when the filter 35 is not abnormal. There is a possibility that an erroneous determination that an abnormality has occurred in the filter 35 is made below the threshold value R.

  Therefore, in this embodiment, when determining the abnormality, the threshold value R is set to a larger value when the intake air amount GA when the differential pressure ΔP is detected is larger than when the intake air amount GA is small.

  FIG. 4 is a flowchart showing a specific processing procedure when performing the above-described abnormality determination processing executed through the electronic control unit 7. This series of processing is repeatedly executed by the electronic control unit 7 with a predetermined period.

  As shown in FIG. 4, in this series of processes, first, it is determined whether or not the PM accumulation amount estimated value Ax is equal to or greater than the regeneration process execution determination value AS (step S11). Here, when the estimated value Ax of the PM accumulation amount is equal to or greater than the regeneration process execution determination value AS (step S11: “YES”), the intake air amount GA and the differential pressure ΔP at that time are read (step S11). S12). Then, a threshold value R is set based on the intake air amount GA with reference to the map shown in FIG. 5 (step S13).

Here, the relationship between the intake air amount GA and the threshold value R will be described with reference to the map of FIG.
As shown in FIG. 5, in this map, the threshold value R is set to a larger value when the intake air amount GA is large than when the intake air amount GA is small. In other words, the threshold value R is set in accordance with the relationship between the intake air amount GA and the differential pressure ΔP shown in FIG.

  When the threshold value R is set in this way, it is determined whether or not the differential pressure ΔP is equal to or less than the threshold value R as shown in FIG. 4 (step S14). As a result, if the differential pressure ΔP is equal to or less than the threshold value R (step S14: “YES”), it is determined that an abnormality has occurred in the filter 35 (step S15), and this process is temporarily terminated.

  On the other hand, when the estimated value Ax of the PM accumulation amount is less than the regeneration process execution determination value AS (step S11: “NO”) or when the differential pressure ΔP is larger than the threshold value R (step S14: “NO”). This processing is once terminated.

  Next, referring to the timing chart of FIG. 6, when the series of processing shown in FIG. 4 is executed, the transition of the estimated value Ax of the PM accumulation amount, the transition of the execution state of the regeneration processing, the transition of the intake air amount GA, The transition of the differential pressure ΔP and the abnormality determination result will be described. It is assumed that no abnormality has occurred in the filter 35 during the period from time t10 to time t15, and abnormality has occurred in the filter 35 at time 15.

  As shown in FIG. 6A, when the PM accumulation amount estimated value Ax becomes the regeneration process stop determination value AE at times t10, t12, t14, and t17, the regeneration is performed as shown in FIG. 6B. Processing will be stopped. When the regeneration process is stopped in this way, as shown in FIG. 6A, the estimated value Ax of the PM accumulation amount gradually increases until the next regeneration process is executed at times t11, t13, t16, and t18. It will be. Further, as shown in FIG. 6E, the differential pressure ΔP gradually increases with an increase in the actual PM deposition amount.

  On the other hand, as shown in FIG. 6A, when the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS at times t11, t13, t16, and t18, as shown in FIG. The reproduction process is started. When the regeneration process is started in this way, as shown in FIG. 6A, the estimated value Ax of the PM accumulation amount gradually decreases until the regeneration process is stopped next at times t12, t14, and t17. . Further, as shown in FIG. 6E, the differential pressure ΔP gradually decreases as the actual amount of accumulated PM decreases.

  Here, when the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS at time t11, abnormality determination is performed by comparing the differential pressure ΔP at this time with the threshold value R. Prior to this, Referring to the map of FIG. 5, a threshold value R used for abnormality determination is set based on the intake air amount GA at that time. Specifically, as shown in FIG. 6C, the intake air amount GAa at time t11, that is, the intake air amount GAa when the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS is relatively small. As shown in FIG. 5, the threshold value R is set to a relatively small value Ra. Since the differential pressure ΔP13 is larger than the threshold value Ra (ΔP13> Ra), as shown in FIG. 6 (f), it is determined that no abnormality has occurred in the filter 35.

  Also, at time t13, the abnormality determination similar to the abnormality determination at the previous time t11 is performed. However, since the intake air amount GAb at time t13 is relatively large as shown in FIG. 6C, the threshold value R is set to a relatively large value Rb according to the intake air amount GAb as shown in FIG. Is done. At this time, since the differential pressure ΔP14 is larger than the threshold value Rb (ΔP14> Rb), it is determined that no abnormality has occurred in the filter 35 as shown in FIG.

  Also, at time t16, the same abnormality determination as that at the previous time t11 and time t13 is performed. Here, as shown in FIG. 6A, in the period from time t14 to time t16, PM is the same as the period from time t10 to time t11 or the period from time t12 to time t13. Although the estimated value Ax of the accumulation amount gradually increases, since an abnormality has occurred in the filter 35 at time t15, as shown in FIG. 6 (e), the differential pressure ΔP is obtained when there is no abnormality in the filter 35. The rate of increase is slower than that. Then, since the differential pressure ΔP12 when the estimated value Ax of the PM accumulation amount reaches the regeneration processing execution determination value AS at time t16 is smaller than the threshold value Rb (ΔP12 <Rb), as shown in FIG. Therefore, it is determined that an abnormality has occurred in the filter 35. Since the intake air amount GAb at time t16 is equal to the intake air amount GAb at time t13, the threshold value R at time t16 is set to a value Rb equal to the threshold value Rb at time t13.

  Also at time t18, the abnormality determination similar to the abnormality determination at the previous time t11, time t13, and time t16 is performed. However, since the intake air amount GAa at time t18 is relatively small as shown in FIG. 6C, the threshold value R is set to a relatively small value Ra according to the intake air amount GAb as shown in FIG. Is done. As in the case of time t16, since the differential pressure ΔP22 is smaller than the threshold Ra (ΔP11 <Ra), it is determined that an abnormality has occurred in the filter 35 as shown in FIG. Become so.

According to the exhaust gas purification apparatus for an internal combustion engine according to the first embodiment described above, the effects listed below can be obtained.
(1) It is determined that there is an abnormality in the filter 35 when the differential pressure ΔPS when the estimated value Ax of the PM accumulation amount is equal to or greater than a predetermined value (= AS). Accordingly, when the estimated value Ax of the PM accumulation amount is equal to or greater than a predetermined value, that is, as shown in FIG. 2, the difference in the case where the filter 35 is abnormal due to the large amount of PM accumulated on the filter 35 is different. The abnormality determination is performed when the difference D between the pressure ΔP1 and the differential pressure ΔP2 when such an abnormality does not occur is relatively large. Therefore, when an abnormality occurs in the filter 35, it can be determined even when the degree of the abnormality is small.

  (2) When the estimated value Ax of the PM accumulation amount is equal to or greater than the regeneration processing execution determination value AS, that is, when the difference between the above-described differential pressures ΔP1 and ΔP2 is at or near the maximum because the PM accumulation amount is at or near the maximum. In addition, the abnormality determination is performed based on the differential pressure ΔP. Thereby, abnormality determination can be performed with higher accuracy.

(3) When determining the abnormality, the threshold value R is set to a larger value when the intake air amount GA when the differential pressure ΔP is detected is larger than when the intake air amount GA is small. As a result, the threshold value R used for abnormality determination is set in accordance with the relationship between the intake air amount GA and the differential pressure ΔP as shown in FIG. For this reason, it can be avoided that an erroneous determination that an abnormality has occurred in the filter 35 is made.
<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.

  In the first embodiment, it is assumed that the flow path resistance of the filter 35 depends only on the amount of accumulated PM and whether or not there is an abnormality. However, in actuality, the filter 35 has individual differences. The flow path resistance when passing through the filter 35 is different for each filter 35. In this case, the differential pressure ΔP1 when there is no abnormality in the filter 35 and the differential pressure ΔP2 when there is an abnormality in the filter 35 deviate from the values when the filter 35 is assumed to be standard. It will be. That is, in the case of the filter 35 whose flow path resistance is larger than that of the standard filter 35, for example, the differential pressures ΔP1 and ΔP2 are larger than the standard differential pressures ΔP1 and ΔP2. For this reason, there is a concern that the reliability of the abnormality determination is lowered due to the influence of individual differences of the filters 35.

  Focusing on this point, in this embodiment, the estimated value Ax of the PM accumulation amount is larger than the first predetermined value from the differential pressure ΔPS when the estimated value Ax of the PM accumulation amount is equal to or greater than the first predetermined value. When the deviation (= ΔPS−ΔPE) obtained by subtracting the differential pressure ΔPE when it is equal to or smaller than the small second predetermined value becomes equal to or smaller than the predetermined threshold R, it is determined that there is an abnormality in the filter 35. In this embodiment, the first predetermined value is set as the reproduction process execution determination value AS, and the second predetermined value is set as the reproduction process stop determination value AE.

  Also, the period during which the regeneration process is stopped is different from the period during which the regeneration process is being executed, and the exhaust temperature may vary greatly depending on which engine operating state at that time, for example, the state where the exhaust temperature Te is high is long. When the integrated value S of the exhaust gas temperature Te is large as in the subsequent case, the oxidation of PM deposited on the filter 35 is promoted more than usual. As a result, the accumulation amount of PM actually deposited on the filter 35, that is, the actual value B of the PM accumulation amount becomes smaller than the estimated value Ax of the PM accumulation amount, and as shown in FIG. It will be small. Therefore, when the oxidation of PM is promoted in this way, even if no abnormality has occurred in the filter 35, the differential pressure ΔP becomes equal to or less than the threshold value R, and the abnormality has occurred in the filter 35. May be misjudged.

  Therefore, in this embodiment, the abnormality determination is a period from when the regeneration process is last stopped until the differential pressure is detected when the estimated value Ax of the PM accumulation amount is equal to or greater than the first predetermined value. When the integral value S of the exhaust gas temperature Te (hereinafter simply referred to as the integral value S of the exhaust gas temperature Te) during the period when the regeneration process is stopped is large, the threshold value R is larger than when the integral value S of the exhaust gas temperature Te is small. Is set to a small value.

  FIG. 8 is a flowchart showing a specific processing procedure for the calculation process of the integral value S of the exhaust temperature Te executed through the electronic control unit 7. FIG. 9 is a flowchart showing a specific processing procedure of the above-described abnormality determination processing that is also executed through the electronic control unit 7. These series of processes are also repeatedly executed by the electronic control unit 7 with a predetermined period.

First, the calculation process of the integral value S of the exhaust temperature Te will be described with reference to FIG.
As shown in FIG. 8, in this series of processes, it is first determined whether or not the reproduction process is stopped (step S201). If the regeneration process is stopped (step S201: “YES”), then the exhaust temperature Te at that time is read (step S202). Next, by adding the current exhaust temperature Te to the integrated value S of the exhaust temperature Te in the previous control cycle, the integrated value S of the exhaust temperature in the current control cycle is calculated (step S203). Is temporarily terminated.

On the other hand, when the reproduction process is being executed (step S201: “NO”), this process is temporarily terminated.
Next, an abnormality determination processing procedure will be described with reference to FIG.

  As shown in FIG. 9, in this series of processes, first, it is determined whether or not the estimated value Ax of the PM accumulation amount is equal to or greater than the regeneration process execution determination value AS (step S21). Here, when the estimated value Ax of the PM accumulation amount is equal to or greater than the regeneration processing execution determination value AS (step S21: “YES”), the integrated value S of the exhaust gas temperature Te and the differential pressure ΔPS at that time are next. Read (step S22). Next, a threshold value R is set based on the integral value S of the exhaust gas temperature Te with reference to the map shown in FIG. 10 (step S23).

Here, the relationship between the integrated value S of the exhaust temperature Te and the threshold value R will be described with reference to the map of FIG.
As shown in FIG. 10, in this map, when the integrated value S of the exhaust temperature Te is large, the threshold value R is set to a smaller value than when the integrated value S of the exhaust temperature Te is small. In other words, the threshold value R is set in accordance with the degree of PM oxidation promotion.

  When the threshold value R is set in this way, the regeneration process is started as shown in FIG. 9 (step S24). Next, the estimated value Ax of the PM accumulation amount is equal to or less than the regeneration process stop determination value AE. Is determined (step S25). The above determination process is repeatedly executed until this condition is satisfied. When the estimated value Ax of the PM accumulation amount becomes equal to or less than the regeneration process stop determination value AE (step S25: “YES”), the differential pressure ΔPE at that time is read. When the differential pressure ΔPE is read in this way, it is determined whether or not a deviation (= ΔPS−ΔPE) obtained by subtracting the differential pressure ΔPE from the differential pressure ΔPS is equal to or less than the threshold value R (step S27). As a result, if the deviation is equal to or less than the threshold value R (step S27: “YES”), it is then determined that an abnormality has occurred in the filter 35 (step S28), and this process is temporarily terminated. To do.

  On the other hand, when the estimated value Ax of the PM accumulation amount is less than the regeneration process execution determination value AS (step S21: “NO”) or when the deviation is larger than the threshold R (step S27: “NO”). This processing is once terminated.

  Next, with reference to the timing chart of FIG. 11, the transition of the estimated value Ax of the PM accumulation amount, the transition of the execution state of the regeneration process, and the integral value of the exhaust gas temperature Te when the series of processes shown in FIG. 9 is performed. The transition of S, the transition of the differential pressure ΔP, and the abnormality determination result will be described. It is assumed that no abnormality has occurred in the filter 35 during the period from time t20 to time t25, and abnormality has occurred in the filter 35 at time 25.

  As shown in FIG. 11E, when the estimated value Ax of the PM accumulation amount becomes the regeneration process stop determination value AE at time t22, the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS at time t21. An abnormality determination is performed by comparing a difference (= ΔP25−ΔP22) obtained by subtracting the differential pressure ΔP22 at time 22 from the differential pressure ΔP25 at which the current value becomes and the threshold value R. Prior to this, the threshold value R is set based on the integrated value S of the exhaust gas temperature Te used for abnormality determination with reference to the map of FIG. Specifically, as shown in FIG. 11C, the integral value S2 of the exhaust temperature Te in the period from the time t20 to the time t21 is relatively large. Therefore, as shown in FIG. The threshold value R is set to a relatively small value R4 according to the value S2. Then, as shown in FIG. 11 (e), the deviation is larger than the threshold value R4 (ΔP25−ΔP22> R4), so that no abnormality has occurred in the filter 35 as shown in FIG. 11 (f). It will be judged.

  Also, at time t24, the abnormality determination similar to the abnormality determination at the previous time t22 is performed. However, as shown in FIG. 11C, the integrated value S1 of the exhaust temperature Te in the period from the time t22 to the time t23 is relatively small. Therefore, as shown in FIG. 10, such an integrated value of the exhaust temperature Te. The threshold value R is set to a relatively large value R3 according to S1. Then, as shown in FIG. 11 (e), the deviation is larger than the threshold value R3 (ΔP26−ΔP22> R3), so that no abnormality has occurred in the filter 35 as shown in FIG. 11 (f). It will be judged.

  Also, at time t27, the abnormality determination similar to the abnormality determination at the previous time t22 and time t24 is performed. Here, as shown in FIG. 11B, in the period from time t24 to time t26, PM deposition is performed as in the period from time t20 to time t21 and the period from time t22 to time t23. Although the estimated value Ax of the quantity increases, since an abnormality has occurred in the filter 35 at time t25, as shown in FIG. 11 (e), the differential pressure ΔP is larger than when no abnormality has occurred in the filter 35. The rate of increase is moderate. Here, the differential pressure ΔP24 when the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS at time t26 is much smaller than the differential pressures ΔP25 and ΔP26 when no abnormality has occurred in the filter 35. Become. On the other hand, the differential pressure ΔP21 when the estimated value Ax of the PM accumulation amount becomes the regeneration process stop determination value AE at time t27 is only slightly smaller than the differential pressure ΔP22 when no abnormality occurs in the filter 35. is there. Then, as shown in FIG. 11 (e), the deviation is equal to or smaller than the threshold value R3 (ΔP24−ΔP21 ≦ R3), and it is determined that an abnormality has occurred in the filter 35 as shown in FIG. 11 (f). The Rukoto.

  At time t29, the same abnormality determination as that at the previous time t22, time t24, and time t27 is performed. However, as shown in FIG. 11C, the integrated value S2 of the exhaust temperature Te in the period from the time t27 to the time t28 is relatively large. Therefore, as shown in FIG. 10, such an integrated value of the exhaust temperature Te. The threshold value R is set to a relatively small value R4 according to S2. As shown in FIG. 11 (e), since the deviation is equal to or less than the threshold value R4 (ΔP23−ΔP21 ≦ R4) as in the case of time t27, the filter 35 is shown in FIG. 11 (f). It is determined that an abnormality has occurred.

According to the exhaust gas purification apparatus for an internal combustion engine according to the second embodiment described above, the following effects can be obtained in addition to the effect (1) of the first embodiment.
(4) From the differential pressure ΔPS when the estimated value Ax of the PM accumulation amount is equal to or greater than the first predetermined value, the estimated value Ax of the PM accumulation amount is equal to or less than a second predetermined value that is smaller than the first predetermined value. When the deviation (= ΔPS−ΔPE) obtained by subtracting the differential pressure ΔPE at that time becomes equal to or less than the predetermined threshold value R, it is determined that the filter 35 is abnormal. Thus, even if the differential pressures ΔPS and ΔPE show different values from the standard filter 35 due to individual differences in the filters 35, by detecting the deviation of the differential pressures ΔPS and ΔPE, Since the influence of such individual differences is canceled out, when an abnormality occurs in the filter 35, it can be determined with higher accuracy.

  (5) In particular, the first predetermined value and the second predetermined value are set to the regeneration process execution determination value AS and the regeneration process stop determination value AE, respectively, and the estimated PM accumulation amount Ax is equal to or greater than the regeneration process execution determination value AS. On the basis of the differential pressure ΔPS when the value becomes equal to or the differential pressure ΔPE when the estimated value Ax of the PM accumulation amount becomes equal to or less than the regeneration processing stop determination value AE, that is, the maximum value of the deviation between the differential pressures ΔPS and ΔPE. Alternatively, the abnormality is determined based on a value close to that. Thereby, abnormality determination can be performed with higher accuracy.

(6) Upon abnormality determination, the regeneration process is stopped during a period from when the regeneration process is last stopped until a differential pressure is detected when the estimated value Ax of the PM accumulation amount is equal to or greater than the first predetermined value. When the integral value S of the exhaust gas temperature Te is large during this period, the threshold value R is set to a smaller value than when the integral value S of the exhaust gas temperature Te is small. In other words, the threshold value R used for abnormality determination is set in accordance with the degree of PM oxidation promotion. As a result, it is possible to avoid an erroneous determination that an abnormality has occurred in the filter 35.
<Third Embodiment>
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. FIG. 12 is a timing chart showing the transition of the estimated value Ax of the PM accumulation amount, the transition of the execution state of the regeneration process, the transition of the actual value B of the PM deposition amount, and the transition of the differential pressure ΔP.

  This embodiment differs from the second embodiment in the following points. That is, as shown in FIG. 12A, when the PM accumulation amount is estimated based on the integrated value of the fuel injection amount, the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS. At the start of the reproduction process, and then at the reproduction process stop determination value AE, that is, at the end of the reproduction process. On the other hand, as shown in FIG. 12C, the actual value B of the PM accumulation amount may change with a delay with respect to the start / end timing of such regeneration processing. Specifically, as shown in FIG. 12A, even when the estimated value Ax of the PM accumulation amount reaches the maximum value AS at time t31, as shown in FIG. 12C, the PM accumulation amount at this time The actual value BS is increasing, and the actual value B of the PM accumulation amount becomes the maximum value Bmax at the subsequent time t32. Further, even if the estimated value Ax of the PM deposition amount becomes the minimum value AE at time t33, as shown in FIG. 12C, the actual value BE of the PM deposition amount at this time is in the process of decreasing, and thereafter At time t34, the actual value B of the PM accumulation amount becomes the minimum value Bmin. Further, since the differential pressure ΔP changes according to the actual value B of the PM accumulation amount, as shown in FIG. 12D, the differential pressure ΔP is the time at which the actual value B of the PM accumulation amount becomes the maximum value Bmax. The maximum value ΔPmax is reached at t32, and the minimum value ΔPmin is reached at time t34 when the actual value B of the PM deposition amount becomes the minimum value Bmin.

  Focusing on this point, in this embodiment, the differential pressure ΔP in the period from when the estimated value Ax of the PM accumulation amount becomes equal to or higher than the regeneration process execution determination value AS to the next time equal to or less than the regeneration process stop determination value AE. Abnormality based on the maximum value ΔPmax and the minimum value ΔPmin of the differential pressure ΔP in the period from when the estimated value Ax of the PM accumulation amount becomes equal to or less than the regeneration process stop determination value AE to the next regeneration process execution determination value AS Judgment is made. In this embodiment, the differential pressure ΔP used for abnormality determination is different from that of the second embodiment, but other configurations are basically the same as those of the second embodiment. For this reason, redundant explanation is omitted here.

  According to the exhaust gas purification apparatus for an internal combustion engine according to the third embodiment described above, the effect (1) of the first embodiment, the effects (4), (5) and (2) of the second embodiment In addition to 6), the following effects can be obtained.

(7) While monitoring the differential pressure ΔP, the maximum of the differential pressure ΔP in the period from when the estimated value Ax of the PM accumulation amount becomes equal to or higher than the regeneration process execution determination value AS to the next lower than the regeneration process stop determination value AE Abnormality based on the value ΔPmax and the minimum value ΔPmin of the differential pressure ΔP in the period from when the estimated value Ax of the PM accumulation amount becomes equal to or less than the regeneration process stop determination value AE to when it next becomes equal to or greater than the regeneration process execution determination value AS Judgment was made. Thereby, even when the actual value B of the PM accumulation amount changes with a delay with respect to the start / end timing of such regeneration processing, the abnormality determination can be performed with higher accuracy.
<Fourth embodiment>
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the following points are different from those of the second embodiment. That is, when the deviation (= ΔPSP−ΔPST) obtained by subtracting the latest value ΔPST from the past value ΔPSP of the differential pressure ΔPS when the estimated value Ax of the PM accumulation amount is equal to or greater than the predetermined value AS becomes equal to or greater than the predetermined threshold Rc. It is determined that the filter 35 is abnormal. Here, the past value ΔPSP of the differential pressure ΔP is the differential pressure ΔPS when there is no abnormality in the filter 35. More specifically, the estimated value Ax of the PM accumulation amount is the regeneration process execution determination value AS for the first time immediately after the engine 1 is manufactured. This is the differential pressure ΔPS when the above is reached.

  FIG. 13 is a flowchart showing a specific processing procedure of the above-described abnormality determination process executed through the electronic control unit 7. FIG. 14 is a timing chart showing the transition of the estimated value Ax of the PM deposition amount, the transition of the execution state of the regeneration process, the transition of the actual value B of the PM deposition amount, the transition of the differential pressure ΔP, and the abnormality determination result. is there. These series of processes are also repeatedly executed by the electronic control unit 7 with a predetermined period.

  As shown in FIG. 13, in this series of processes, first, it is determined whether or not the estimated value Ax of the PM accumulation amount is equal to or greater than the regeneration process execution determination value AS (step S41). Here, when the estimated value Ax of the PM accumulation amount is equal to or greater than the regeneration processing execution determination value AS (step S41: “YES”), next, the differential pressure ΔPST at that time, that is, the latest value ΔPST of the differential pressure ΔPS. Is read (step S42). Next, it is determined whether or not a deviation (= ΔPSP−ΔPST) obtained by subtracting the current differential pressure ΔPST from the past value ΔPSP of the differential pressure ΔPS is equal to or smaller than a predetermined threshold value Rc (step S43). Here, the predetermined threshold value Rc is a fixed value set in advance through experiments. As a result, if the deviation is equal to or greater than the threshold value Rc (step S43: “YES”), it is then determined that an abnormality has occurred in the filter 35 (step S44), and this process is temporarily terminated. To do. On the other hand, when the estimated value Ax of the PM accumulation amount is less than the regeneration process execution determination value AS (step S41: “NO”) or when the deviation is smaller than the threshold R (step S43: “NO”). This processing is once terminated.

  Next, referring to the timing chart of FIG. 14, when the series of processes shown in FIG. 13 is executed, the transition of the estimated value Ax of the PM accumulation amount, the transition of the execution state of the regeneration process, the transition of the differential pressure ΔP, The abnormality determination result will be described. It is assumed that no abnormality has occurred in the filter 35 during the period from time t40 to time t45, and abnormality has occurred in the filter 35 at time 45. Here, the description will be made assuming that the past value ΔPSP of the differential pressure ΔP is the differential pressure ΔP41.

  As shown in FIG. 14A, when the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS at time t41, the differential pressure ΔP41 at this time, that is, the difference from the past value ΔP41 of the differential pressure ΔP. The abnormality determination is performed by comparing a deviation (= ΔP41−ΔP41) obtained by subtracting the latest value ΔP41 of the pressure ΔP with the threshold value Rc. Then, as shown in FIG. 14D, the deviation is “0”, which is smaller than the threshold value Rc (ΔP41−ΔP41 <Rc). Therefore, as shown in FIG. It is determined that it has not occurred.

  Also, at time t43, the abnormality determination similar to the abnormality determination at the previous time t41 is performed. As shown in FIG. 14 (d), since the deviation is smaller than the threshold value Rc in this case as well (ΔP41−ΔP42 <Rc), there is an abnormality in the filter 35 as shown in FIG. 14 (f). It is determined that it has not occurred.

  Also, at time t46, the abnormality determination similar to the abnormality determination at the previous time t41 and time t43 is performed. In this case, as shown in FIG. 14D, the deviation is equal to or greater than the threshold value Rc (ΔP41−ΔP43 ≧ Rc), so that the filter 35 has an abnormality as shown in FIG. It is determined that it has occurred.

  Also, at time t48, the abnormality determination similar to the abnormality determination at the previous time t41, time t43, and time t46 is performed. Then, as shown in FIG. 14 (d), the deviation is equal to or greater than the threshold value Rc (ΔP41−ΔP44 ≧ R4), so that an abnormality has occurred in the filter 35 as shown in FIG. 14 (f). It will be judged.

According to the exhaust gas purification apparatus for an internal combustion engine according to the fourth embodiment described above, the following effects can be obtained in addition to the effect (1) of the first embodiment.
(8) A deviation (= ΔPSP−ΔPST) obtained by subtracting the latest value ΔPST of the differential pressure ΔP from the past value ΔPSP of the differential pressure ΔP when the estimated value Ax of the PM accumulation amount becomes equal to or greater than the first predetermined value. It is determined that there is an abnormality in the filter 35 when the predetermined threshold value Rc is exceeded. Thereby, even when the flow path resistance differs for each filter 35 due to individual differences of the filters 35, it is possible to determine this with higher accuracy when an abnormality occurs in the filter 35.

(9) In particular, the first predetermined value is set to the reproduction process execution determination value AS. Thereby, abnormality determination can be performed with higher accuracy.
Note that the exhaust gas purification apparatus for an internal combustion engine according to the present invention can be implemented as, for example, the following forms in which the above-described embodiments are appropriately changed.

  In the first embodiment, the threshold value R is set based on the intake air amount GA with reference to the map of FIG. 5 when determining abnormality, but the setting mode of the threshold value R is not limited to this. Absent. In short, the threshold R may be set to a larger value (provided with a threshold setting means) when the intake air amount GA when the differential pressure ΔP is detected is larger than when the intake air amount GA is small.

  In addition to or in place of the threshold value setting means of the first embodiment, when the integral value S of the exhaust temperature Te is large in the abnormality determination as in the second embodiment, the same exhaust temperature The threshold value R may be set to a smaller value than when the integrated value S of Te is small. Further, the threshold value R may be a fixed value as in the fourth embodiment.

  In the first embodiment, the predetermined value used in the abnormality determination is set as the reproduction process execution determination value AS. However, the predetermined value is not limited to this, and the predetermined value is reproduced. It is also possible to set a value smaller than the execution determination value AS. Further, if the abnormality determination is performed based on the maximum value ΔPmax of the differential pressure ΔP as in the third embodiment, the abnormality determination can be performed with higher accuracy. In short, what is necessary is just to determine that there is an abnormality in the filter when the differential pressure when the estimated value Ax of the PM accumulation amount is equal to or greater than a predetermined value is equal to or less than a predetermined threshold value.

  In the second embodiment, the estimated value Ax of the PM deposition amount is equal to or less than the regeneration processing stop determination value AE from the differential pressure ΔPS when the estimated value Ax of the PM deposition amount is equal to or higher than the regeneration processing execution determination value AS. The deviation (= ΔPS−ΔPE) obtained by subtracting the differential pressure ΔPE at the time of becoming is adopted as a parameter indicating the divergence degree of these differential pressures ΔPS, ΔPE, but this divergence degree is not limited to this. . In addition, for example, the degree of divergence may be calculated based on the ratio between the differential pressures ΔPS and ΔPE.

  In the second and third embodiments, the threshold value R is set based on the integral value S of the exhaust gas temperature Te with reference to the map of FIG. Is not limited to this. In short, what is necessary is just to include a threshold setting means for setting the threshold R to a smaller value when the integrated value S of the exhaust temperature Te is larger than when the integrated value S of the exhaust temperature Te is small.

  In the second and third embodiments, since the first predetermined value used for the abnormality determination is set as the regeneration process execution determination value AS, the PM accumulation after the regeneration process is finally stopped The threshold value R is set based on the integral value S of the exhaust gas temperature Te in a period until the estimated value Ax of the amount becomes equal to or higher than the regeneration process execution determination value AS. However, for example, when the first predetermined value used in the abnormality determination is set to a value smaller than the regeneration process execution determination value AS, the estimated value Ax of the PM accumulation amount becomes the regeneration process execution determination value AS, and thereafter In the configuration in which an abnormality is determined when the above value is reached, the integration period for calculating the integrated value of the exhaust gas temperature Te may be changed as follows. That is, a period until an abnormality determination is further made may be added to a period until the estimated value Ax of the PM accumulation amount becomes equal to or higher than the regeneration process execution determination value AS after the regeneration process is stopped last. In short, at the time of abnormality determination, when the integral value S of the exhaust gas temperature Te during the same period is large during at least the period from the time when the regeneration process is stopped to the time when the abnormality determination is made and the regeneration process is stopped. What is necessary is just to have a threshold value setting means for setting the threshold value R to a smaller value than when the integrated value S of the exhaust temperature Te is small.

  In addition to or instead of the threshold value setting means of the second and third embodiments, when the integral value S of the exhaust temperature Te is large at the time of abnormality determination as in the first embodiment, The threshold value R may be set to a smaller value than when the integrated value S of the exhaust temperature Te is small. When the intake air amount GA is large when the differential pressure ΔP is detected, the threshold value R may be set to a larger value than when the intake air amount GA is small. Further, the threshold value R may be a fixed value as in the fourth embodiment.

  In the second and third embodiments, the first predetermined value used for the abnormality determination is set as the reproduction process execution determination value AS, and the second predetermined value is set as the reproduction process stop determination value AE. However, the first predetermined value and the second predetermined value are not limited to this, and can be arbitrarily changed. That is, the first predetermined value may be set to a value smaller than the reproduction process execution determination value AS, and the second predetermined value may be set to a value larger than the reproduction process stop determination value AE. In short, the differential pressure when the estimated value of the PM accumulation amount is equal to or greater than the first predetermined value and the estimated value of the PM accumulation amount is equal to or less than the second predetermined value that is smaller than the first predetermined value. Any method may be used as long as it compares with the differential pressure and determines that there is an abnormality in the filter when the divergence degree of these differential pressures is equal to or less than a predetermined threshold.

  In the fourth embodiment, the threshold value Rc is a fixed value, but the threshold value is based on the intake air amount GA when the latest value ΔPST of the differential pressure ΔP is detected, for example, as in the first embodiment. R may be variably set, and the threshold value R is variably set based on the integral value S of the exhaust gas temperature Te in the stop period immediately before the regeneration processing, as in the second and third embodiments. You may do it. Further, the maximum value of the differential pressure ΔP when the estimated value Ax of the PM accumulation amount is equal to or greater than the predetermined value AS is learned and updated, and the maximum value of the differential pressure ΔP that is appropriately updated is set as the past value ΔPSP. You may make it do.

  In the fourth embodiment, the deviation (= ΔPSP) obtained by subtracting the latest value ΔPST of the differential pressure ΔPS from the past value ΔPSP of the differential pressure ΔPS when the estimated value Ax of the PM accumulation amount is equal to or greater than the predetermined value AS. −ΔPST) is employed as a parameter indicating the degree of deviation between these differential pressures ΔPSP and ΔPST, but the degree of deviation according to the present invention is not limited to this. Alternatively, for example, the degree of divergence may be calculated based on the ratio between the differential pressures ΔPSP and ΔPST.

  In the fourth embodiment, the reproduction process execution determination value AS is adopted as the predetermined value AS used for abnormality determination. However, the predetermined value is not limited to this, and the predetermined value is reproduced. It is also possible to set a value smaller than the process execution determination value AS. Further, if the abnormality determination is performed based on the maximum value ΔPmax of the differential pressure ΔP as in the third embodiment, the abnormality determination can be performed with higher accuracy. In short, the latest value of the differential pressure when the estimated value of the PM accumulation amount is equal to or greater than a predetermined value is compared with the past value of the differential pressure, and the degree of divergence between these differential pressures is greater than or equal to a predetermined threshold. It may be anything that determines that there is an abnormality in the filter.

  In each of the above embodiments, the differential pressure ΔP between the pressure on the exhaust upstream side of the filter 35 and the pressure on the downstream side of the exhaust is directly detected by the differential pressure sensor 64. The pressure difference detecting means to detect is not limited to this. For example, the pressure upstream of the filter 35 and the pressure on the downstream side of the filter 35 are separately detected, and the difference between them is calculated indirectly. May be detected automatically. Further, in this case, the pressure upstream of the filter 35 may be directly detected by a pressure sensor, and the pressure downstream of the filter 35 may be estimated based on the engine operating state. Specifically, the exhaust flow rate is directly detected, and the absolute pressure on the exhaust downstream side of the filter 35 is estimated based on the detected exhaust flow rate and the flow path resistance on the exhaust downstream side of the filter 35. The gauge pressure on the exhaust downstream side of the filter 35 is calculated by subtracting the atmospheric pressure from the absolute pressure. Then, the differential pressure ΔP may be detected by calculating the difference between the gauge pressure on the exhaust upstream side of the filter 35 and the gauge pressure on the exhaust downstream side.

  In each of the above embodiments, the temperature of the filter 35 is raised by fuel injection into the exhaust passage 33 by the fuel addition valve 42. However, instead of the fuel injection by the fuel addition valve 42, or the fuel addition valve 42 In addition to the fuel injection by 42, the temperature of the filter 35 may be raised by executing post fuel injection by injecting fuel during the exhaust stroke by the fuel injection valve 41.

  In each of the above embodiments, the temperature of the filter 35 is raised to a predetermined temperature or higher through addition injection by the fuel addition valve 42 or post injection by the fuel injection valve 41, but the temperature of the filter 35 is higher than the predetermined temperature. The configuration for raising the filter 35 is not limited to this, and the filter 35 may be heated by an electric heater or the like, for example. In short, when the estimated value Ax of the PM accumulation amount becomes equal to or higher than the predetermined regeneration process execution determination value AS, the regeneration process of raising the temperature of the filter 35 to a predetermined temperature or higher and burning the PM to remove it from the filter 35. What is necessary is just to perform.

  In each of the above embodiments, the PM accumulation amount accumulated on the filter 35 is estimated based on the integrated value of the fuel injection amount and the fuel addition amount. It is not limited to. In short, this can be arbitrarily changed as long as the PM accumulation amount accumulated on the filter 35 is estimated based on the engine operation state.

  In each of the above embodiments, a diesel engine is illustrated, but the engine is not limited to this, and the present invention can also be applied to a gasoline engine. Further, the present invention can be applied to an exhaust gas purification device for a marine engine or a stationary power internal combustion engine in addition to an in-vehicle engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a diesel engine control device, an engine to which the diesel engine control device is applied, and peripheral configurations thereof for an internal combustion engine exhaust gas purification apparatus according to a first embodiment of the present invention; The graph which showed the relationship between the actual value B of PM deposition amount, and differential pressure (DELTA) P. The graph which showed the relationship between intake air amount GA and differential pressure (DELTA) P. The flowchart which showed the specific process sequence of the abnormality determination process performed through the electronic controller in the same embodiment. A map showing the relationship between the intake air amount GA and the threshold value R. (A) Transition of estimated value Ax of PM accumulation amount, (b) Transition of execution state of regeneration processing, (c) Transition of intake air amount GA, (d) Presence / absence of abnormality of filter 35, (e) Difference in pressure ΔP The timing chart which shows transition and (f) abnormality determination result. The graph which showed the relationship between the integral value S of the exhaust temperature Te in the stop period of a regeneration process, and the pressure difference (DELTA) P when the estimated value Ax of PM deposition amount turns into the regeneration process execution determination value AS. The flowchart which showed the specific process sequence of the calculation process of the integral value S of the exhaust temperature Te performed through the electronic controller in 2nd Embodiment of this invention. The flowchart which showed the specific process sequence of the abnormality determination process performed through the electronic controller in the same embodiment. The map which showed the relationship between the integral value S and the threshold value R of exhaust temperature Te in the stop period of a regeneration process. (A) Transition of estimated value Ax of PM accumulation amount, (b) Transition of execution state of regeneration processing, (c) Transition of intake air amount GA, (d) Presence / absence of abnormality of filter 35, (e) Difference in pressure ΔP The timing chart which shows transition and (f) abnormality determination result. Regarding the exhaust gas purification apparatus for an internal combustion engine according to the third embodiment of the present invention, (a) the transition of the estimated value Ax of the PM deposition amount, (b) the transition of the execution state of the regeneration process, (c) the PM deposition amount 9 is a timing chart showing a transition of an actual value B and (d) a transition of a differential pressure ΔP. The flowchart which showed the specific process sequence of the abnormality determination process performed through an electronic controller about the exhaust gas purification apparatus of the internal combustion engine concerning 4th Embodiment of this invention. (A) Transition of estimated value Ax of PM accumulation amount, (b) Transition of execution state of regeneration process, (c) Presence / absence of abnormality of filter 35, (e) Transition of differential pressure ΔP, and (f) Abnormality determination result The timing chart which shows.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine, 21 ... Intake port, 22 ... Intake valve, 23 ... Intake passage, 24 ... Throttle valve, 25 ... Motor, 31 ... Exhaust port, 32 ... Exhaust valve, 33 ... Exhaust passage, 34 ... Catalytic converter, 35 ... Filter, 41 ... Fuel injection valve, 42 ... Fuel addition valve, 5 ... Combustion chamber, 61 ... Air flow meter, 62 ... Throttle opening sensor, 63 ... Exhaust temperature sensor, 64 ... Differential pressure sensor, 7 ... Electronic control device.

Claims (14)

A filter provided in the exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust; an estimation means for estimating the amount of particulate matter deposited on the filter based on the engine operating state; When the estimated amount of deposited material reaches or exceeds the predetermined regeneration processing execution judgment value, the regeneration temperature is increased to the predetermined temperature or higher to burn particulate matter and remove it from the filter. In an exhaust gas purification apparatus for an internal combustion engine comprising a regeneration processing control means for
Differential pressure detection means for detecting a differential pressure between the pressure on the exhaust upstream side of the filter and the pressure on the downstream side of the exhaust;
Abnormality determining means for determining that the filter is abnormal when the differential pressure when the estimated amount of particulate matter estimated by the estimating means is equal to or greater than a predetermined value is equal to or less than a predetermined threshold; An exhaust emission control device for an internal combustion engine, comprising: The exhaust gas purification apparatus for an internal combustion engine according to claim 1,
The internal combustion engine characterized in that the abnormality determination means performs abnormality determination based on the differential pressure when an estimated amount of particulate matter accumulation estimated by the estimation means is equal to or greater than the regeneration processing execution determination value. Exhaust purification equipment. The exhaust gas purification apparatus for an internal combustion engine according to claim 1,
The abnormality determination unit monitors the differential pressure, and performs the regeneration after the estimated amount of particulate matter accumulated estimated by the estimation unit becomes equal to or greater than the regeneration process execution determination value and the regeneration process is started. An exhaust gas purification apparatus for an internal combustion engine, wherein abnormality determination is performed based on a maximum value of the differential pressure during a period until processing is stopped. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3,
In the abnormality determination by the abnormality determination means, the apparatus further comprises threshold setting means for setting the threshold value to a larger value when the intake air amount when the differential pressure is detected is larger than when the intake air amount is small. An exhaust purification device for an internal combustion engine. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 4,
Exhaust temperature detecting means for detecting the temperature of the exhaust gas flowing into the filter;
In the abnormality determination by the abnormality determination means, it is a period from when the regeneration process is last stopped until the differential pressure is detected when the estimated amount of accumulated particulate matter is equal to or greater than the predetermined value. A threshold value setting means for calculating an integral value of the exhaust gas temperature during a period when the regeneration process is stopped, and setting the threshold value to a smaller value when the calculated integral value is larger than when the integral value is small; An exhaust emission control device for an internal combustion engine, further comprising: A filter provided in the exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust; an estimation means for estimating the amount of particulate matter deposited on the filter based on the engine operating state; When the estimated amount of deposited material reaches or exceeds the predetermined regeneration processing execution judgment value, the regeneration temperature is increased to the predetermined temperature or higher to burn particulate matter and remove it from the filter. When the regeneration process is being performed, the regeneration process is stopped when the estimated amount of particulate matter accumulated becomes equal to or less than a predetermined regeneration process stop determination value that is smaller than the regeneration process execution determination value. In an exhaust gas purification apparatus for an internal combustion engine comprising a processing control means,
Differential pressure detection means for detecting a differential pressure between the pressure on the exhaust upstream side of the filter and the pressure on the downstream side of the exhaust;
The differential pressure when the estimated amount of particulate matter estimated by the estimating means is greater than or equal to a first predetermined value, and a second predetermined value that is less than the first predetermined value. An abnormality determining means that compares the differential pressure when the difference is less than or equal to a value, and determines that the filter is abnormal when the degree of divergence between the differential pressures is less than or equal to a predetermined threshold value. An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to claim 6,
The abnormality determination means includes the differential pressure when the particulate matter accumulation amount estimated value estimated by the estimation means is greater than or equal to the regeneration processing execution determination value, and the accumulation amount estimation value is the regeneration processing stop determination value. An exhaust gas purification apparatus for an internal combustion engine, wherein abnormality determination is performed based on the differential pressure when: The exhaust gas purification apparatus for an internal combustion engine according to claim 6,
The abnormality determination means monitors the differential pressure, and then the particulate matter accumulation amount estimated value estimated by the estimation means becomes equal to or higher than the regeneration process execution determination value and then the regeneration process stop determination value or less. The maximum value of the differential pressure in the period until the value becomes and the estimated value of the differential pressure in the period until the accumulated amount estimated value becomes less than the regeneration process stop judgment value and then becomes the regeneration process execution judgment value or more. An exhaust gas purification apparatus for an internal combustion engine, wherein abnormality determination is performed based on the minimum value. The exhaust emission control device for an internal combustion engine according to any one of claims 6 to 8,
Exhaust temperature detecting means for detecting the temperature of the exhaust gas flowing into the filter;
During the abnormality determination by the abnormality determination means, the period from when the regeneration process was last stopped until the differential pressure is detected when the particulate matter accumulation amount estimated value is greater than or equal to the first predetermined value A threshold value setting for calculating an integral value of the exhaust gas temperature during a period when the regeneration process is stopped, and setting the threshold value to a smaller value when the calculated integral value is larger than when the integral value is small An exhaust purification device for an internal combustion engine, further comprising: means. A filter provided in the exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust; an estimation means for estimating the amount of particulate matter deposited on the filter based on the engine operating state; When the estimated amount of deposited material reaches or exceeds the predetermined regeneration processing execution judgment value, the regeneration temperature is increased to the predetermined temperature or higher to burn particulate matter and remove it from the filter. In an exhaust gas purification apparatus for an internal combustion engine comprising a regeneration processing control means for
Differential pressure detection means for detecting a differential pressure between the pressure on the exhaust upstream side of the filter and the pressure on the downstream side of the exhaust;
The latest value of the differential pressure when the estimated amount of particulate matter estimated by the estimating means is equal to or greater than a predetermined value is compared with the past value, and the difference between these differential pressures is equal to or greater than a predetermined threshold. An exhaust gas purifying device for an internal combustion engine, comprising: an abnormality determining unit that determines that the filter has an abnormality when the engine becomes abnormal. The exhaust gas purification apparatus for an internal combustion engine according to claim 10,
The abnormality determination means performs an abnormality determination based on the latest value of the differential pressure and the past value when the accumulated amount estimated value of the particulate matter estimated by the estimation means is equal to or greater than the regeneration processing execution determination value. An exhaust emission control device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to claim 10,
The abnormality determination unit monitors the differential pressure, and performs the regeneration after the estimated amount of particulate matter accumulated estimated by the estimation unit becomes equal to or greater than the regeneration process execution determination value and the regeneration process is started. An exhaust gas purification apparatus for an internal combustion engine, wherein abnormality determination is performed based on a latest value and a past value of the maximum value of the differential pressure in a period until processing is stopped. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 10 to 12,
In the abnormality determination by the abnormality determination means, the apparatus includes a threshold setting means for setting the threshold to a smaller value when the intake amount when the latest value of the differential pressure is detected is larger than when the intake amount is small. An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 10 to 13,
Exhaust temperature detecting means for detecting the temperature of the exhaust gas flowing into the filter;
During the abnormality determination by the abnormality determination means, a period from when the regeneration process was last stopped until the latest value of the differential pressure when the particulate matter accumulation amount estimated value is equal to or greater than the predetermined value is detected. A threshold value setting for calculating an integral value of the exhaust temperature during a period when the regeneration process is stopped, and setting the threshold value to a larger value when the calculated integral value is larger than when the integral value is small An exhaust purification device for an internal combustion engine, further comprising: means.

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