JP2015218605A - Internal combustion engine exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine exhaust emission control device including a filter and an oxidation catalyst, capable of accurately grasping the situation of PM deposition on an exhaust-inlet-side end surface of the oxidation catalyst.SOLUTION: An exhaust emission control device including a filter provided in an exhaust passage of an internal combustion engine and collecting particulate matters in exhaust gas, and an oxidation catalyst provided in the exhaust passage of the internal combustion engine and located upstream of the filter, comprises: a first calculation unit calculating a PM discharge amount that is an integrated amount of the particulate matters contained in the exhaust gas discharged from the internal combustion engine and flowing into the filter on the basis of an engine rotation speed, an engine load, and an intake air quantity; a second calculation unit calculating a PM deposition amount that is a deposition amount of the particulate matters collected by the filter on the basis of an exhaust pressure difference between an upstream side and a downstream side of the filter and a flow volume and a temperature of the exhaust gas flowing into the filter; and a third calculation unit calculating an end surface clogging rate that is a clogging rate on an exhaust inlet-side end surface of the oxidation catalyst on the basis of the PM discharge amount calculated by the first calculation unit and the PM deposition amount calculated by the second calculation unit.

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

  In the internal combustion engine, a filter is provided in the exhaust passage in order to prevent particulate matter (hereinafter referred to as “PM”) in the exhaust from being discharged to the outside. Since the PM in the exhaust gas is collected and gradually accumulated in the filter with the operation of the internal combustion engine, a filter regeneration process is performed to prevent clogging. For example, in filter regeneration processing in a diesel engine, since the air-fuel ratio of exhaust gas is generally the lean air-fuel ratio, unburnt fuel is supplied into the exhaust gas and exhausted with an oxidation catalyst or the like provided in the exhaust passage. The temperature is raised, so that the collected PM is removed by oxidation. In order to appropriately execute such filter regeneration processing, it is necessary to grasp the PM accumulation amount in the filter. For example, the technique disclosed in Patent Document 1 can be employed.

  In addition to the filter, an exhaust gas purification catalyst for purifying NOx and the like in the exhaust gas is disposed in the exhaust passage of the internal combustion engine. There is a possibility that PM also accumulates in the exhaust purification catalyst, and the accumulation of PM may make it difficult to exhibit the original exhaust purification ability. In particular, PM accumulation is likely to occur in an exhaust purification catalyst arranged on the upstream side of the filter. Therefore, according to the technique disclosed in Patent Document 2, the exhaust gas temperature is further taken into consideration in the PM emission amount calculated from the engine speed of the internal combustion engine, the engine load and the intake air amount. Thus, the clogged state due to PM in the exhaust purification catalyst is grasped.

JP 2013-234595 A JP 2007-32533 A JP2013-234610A

  When a filter is disposed in the exhaust passage of the internal combustion engine, an oxidation catalyst may be disposed on the upstream side of the filter for the purpose of oxidizing and removing PM accumulated on the filter. Since this oxidation catalyst is located on the upstream side of the filter, it is often exposed to PM in the exhaust gas. As a result, PM accumulates on the end surface of the oxidation catalyst on the exhaust inflow side, causing the oxidation catalyst to become clogged. Cheap. If the oxidation catalyst is clogged with PM, the flow of exhaust gas in the exhaust passage is hindered or the oxidation ability of the oxidation catalyst is prevented from being exhibited, so that the clogged state is promptly eliminated.

  However, the above-described conventional technique calculates the clogging rate due to PM in the exhaust purification catalyst, and does not focus on clogging on the exhaust inflow side end face of the exhaust purification catalyst in which PM easily flows and accumulates. Since the transition of PM deposition on the exhaust inflow side end face is different from the deposition transition in other parts and the deposition transition in the entire catalyst when the exhaust purification catalyst is viewed for each part, in the prior art, the exhaust purification catalyst exhaust gas It is difficult to accurately grasp the state of PM deposition on the inflow side end face.

  The present invention has been made in view of the above-described problems. In an exhaust gas purification apparatus for an internal combustion engine having a filter and an oxidation catalyst, PM deposition on the exhaust gas inflow side end surface of the oxidation catalyst located upstream of the filter is performed. The purpose is to grasp the situation accurately.

  In the present invention, in order to solve the above-mentioned problem, the amount of PM emission calculated based on the operating state of the internal combustion engine and the upstream side and the downstream side of the filter reflecting the state of PM accumulation in the actual filter The difference from the PM accumulation amount calculated from the exhaust pressure difference was noted. This is because the present applicant has found that the difference increases as PM deposition progresses on the exhaust inflow side end face of the oxidation catalyst located on the upstream side of the filter.

  Specifically, the present invention is an exhaust gas purification apparatus for an internal combustion engine, which is provided in an exhaust passage of the internal combustion engine and collects particulate matter in the exhaust, and the exhaust passage upstream of the filter. And an integrated amount of particulate matter contained in the exhaust gas discharged from the internal combustion engine and flowing into the filter based on the engine speed of the internal combustion engine, the engine load in the internal combustion engine, and the intake air amount The particulate matter collected by the filter based on the first calculation unit for calculating the PM emission amount, the exhaust pressure difference between the upstream side and the downstream side of the filter, the flow rate and temperature of the exhaust gas flowing into the filter A second calculation unit that calculates a PM deposition amount that is a deposition amount of a substance; and a difference between the PM emission amount calculated by the first calculation unit and the PM deposition amount calculated by the second calculation unit. And Comprising serial and third calculation unit for calculating an end face clogging index is a clogging ratio of the end surface of the exhaust inlet side of the oxidation catalyst.

  The exhaust gas purification apparatus according to the present invention mainly collects PM in the exhaust gas by the configuration in which the filter is provided in the exhaust passage. Here, the first calculation unit calculates the integrated amount of PM contained in the exhaust gas discharged from the internal combustion engine and flowing into the filter. Since the PM amount in the exhaust gas depends on the combustion state of the fuel in the internal combustion engine, the calculation by the first calculation unit is performed based on the engine rotational speed, the engine load, and the intake air amount of the internal combustion engine.

  Further, the exhaust purification apparatus includes a second calculation unit, and unlike the first calculation unit, the second calculation unit calculates the amount of PM collected and accumulated in the filter. Specifically, based on the fact that the PM accumulation amount in the filter has a strong correlation with the exhaust pressure difference between the upstream side and the downstream side of the filter, the second calculation unit uses the exhaust pressure difference to perform PM deposition. The amount is calculated. The exhaust pressure difference is an exhaust pressure difference at a location across the entire filter, so the PM accumulation amount calculated by the second calculation unit is the PM amount accumulated in the entire filter. In addition, the second calculation unit uses the exhaust gas flow rate and the exhaust temperature in addition to the exhaust pressure difference, thereby making it possible to accurately calculate the PM deposition amount by eliminating the influence of the operating state of the internal combustion engine as much as possible. To do.

  Here, in the exhaust passage of the internal combustion engine, PM in the exhaust gas is collected by the filter, and its release to the outside is suppressed, but the exhaust gas flowing into the filter is raised to oxidize the PM collected in the filter. An oxidation catalyst is disposed upstream of the filter for removal and the like. However, since the oxidation catalyst is located on the upstream side of the filter, the exhaust before PM removal by the filter is performed flows, and there is a possibility that PM is deposited on the oxidation catalyst as well. In particular, PM deposition tends to be noticeable on the end surface of the oxidation catalyst on the exhaust inflow side. When PM accumulates on the oxidation catalyst in this way and its end face becomes clogged with PM, the flow of exhaust gas in the exhaust passage is obstructed and the combustion efficiency of the internal combustion engine is affected. Further, when the amount of PM deposited on the oxidation catalyst increases, it becomes difficult to effectively exhibit its oxidation ability. Therefore, it is preferable that the PM accumulation state on the end surface of the oxidation catalyst on the exhaust inflow side, that is, the clogged state due to PM on the end surface can be accurately detected. This makes it possible to grasp the clogged state at the exhaust inflow side end surface of the oxidation catalyst in a timely manner and to solve it.

Therefore, in the exhaust gas purification apparatus for an internal combustion engine according to the present invention, attention is paid to the difference between the PM emission amount calculated by the first calculation unit and the PM accumulation amount calculated by the second calculation unit. This is because the present applicant has found that the difference increases when PM deposition on the exhaust inflow side end face becomes significant in the oxidation catalyst. That is, assuming that the filter collects PM discharged from the internal combustion engine, if there is a difference between the amount of PM discharged from the internal combustion engine and the amount of PM deposited on the filter, the difference It can be reasonably considered that the corresponding PM is trapped by the oxidation catalyst. Therefore, the third calculation unit calculates the state of PM accumulation on the exhaust inflow side end surface of the oxidation catalyst, that is, the end surface clogging rate, which is the clogging rate due to PM, on the end surface based on the above difference. Composed. The end face clogging rate is a parameter indicating the ratio of the space volume occupied by PM in the space volume through which exhaust gas can flow on the end face of the oxidation catalyst. Therefore, the state where the end surface clogging rate is 100% means that the exhaust catalyst inflow end surface of the oxidation catalyst is completely blocked by PM.

  By adopting such a configuration, the exhaust gas purification apparatus for an internal combustion engine according to the present invention can suitably detect PM accumulation on the exhaust inflow side end face of the oxidation catalyst. As described above, if the clogging rate at the end face on the exhaust inflow side of the oxidation catalyst that is not originally installed for PM collection becomes higher, the resistance of the exhaust flow in the exhaust passage becomes higher. It is preferable to eliminate the above appropriately. In this case, a process of raising the temperature of the oxidation catalyst to a temperature suitable for PM removal can be employed.

  According to the present invention, in an exhaust gas purification apparatus for an internal combustion engine having a filter and an oxidation catalyst, it is possible to accurately grasp the state of PM deposition on the exhaust inflow side end face of the oxidation catalyst located upstream of the filter. .

It is a figure showing a schematic structure of an exhaust-air-purification device of an internal-combustion engine concerning the present invention. 2 is a flowchart of regeneration control that is executed by the exhaust gas purification apparatus for an internal combustion engine shown in FIG. 1. It is a figure which shows the correlation with the exhaust pressure difference of the upstream and downstream of a filter, and the amount of PM deposits in this filter. It is a figure which shows the correlation with the difference amount of PM amount discharged | emitted from the internal combustion engine, and the PM accumulation amount in a filter, and the clogging rate in the exhaust gas inflow side end surface of a filter.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

  FIG. 1 shows a schematic configuration of an exhaust emission control device for an internal combustion engine 1 according to the present invention. The internal combustion engine 1 is a diesel engine for driving a vehicle. An exhaust passage 2 is connected to the internal combustion engine 1. The exhaust passage 2 is provided with a particulate filter 4 (hereinafter simply referred to as “filter”) that collects PM in the exhaust. An oxidation catalyst 3 is provided upstream of the filter 4 in the exhaust passage 2. The oxidation catalyst 3 has a function of oxidizing unburned fuel components, NO, and the like in the inflowing exhaust gas.

A fuel supply valve 5 for supplying fuel (unburned fuel) to the exhaust gas flowing into the oxidation catalyst 3 is provided upstream of the oxidation catalyst 3. A temperature sensor 6 for measuring the temperature of the exhaust gas flowing into the oxidation catalyst 3 and a temperature sensor 7 for measuring the temperature of the exhaust gas flowing out of the oxidation catalyst 3 are provided upstream and downstream of the oxidation catalyst 3. . Further, in the vicinity of the filter 4, the difference between the exhaust pressure in the temperature sensor 9 that detects the temperature of the exhaust gas flowing in the exhaust passage 2 downstream of the filter 4 and the upstream and downstream exhaust passages sandwiching the filter 4 is calculated. A differential pressure sensor 8 for detection is also provided.

  An air flow meter 10 capable of measuring an intake air flow rate flowing through the intake passage 13 is disposed in the intake passage 13 of the internal combustion engine. The internal combustion engine 1 is provided with an electronic control unit (ECU) 20 that controls the operating state of the internal combustion engine 1 and the like. The ECU 20 is electrically connected to the above-described fuel supply valve 5, temperature sensors 6, 7, 9, differential pressure sensor 8, air flow meter 10, crank position sensor 11, accelerator opening sensor 12, and the like, and the fuel supply valve 5 performs fuel supply control to the exhaust gas in accordance with an instruction from the ECU 20, and detection values from the sensors are passed to the ECU 20. For example, the crank position sensor 11 detects the crank angle of the internal combustion engine 1, and the accelerator opening sensor 12 detects the accelerator opening of the vehicle on which the internal combustion engine 1 is mounted and sends it to the ECU 20. As a result, the ECU 20 derives the engine rotation speed of the internal combustion engine 1 based on the detection value of the crank position sensor 11 and derives the engine load of the internal combustion engine 1 based on the detection value of the accelerator opening sensor 12. The ECU 20 detects the exhaust temperature flowing into the oxidation catalyst 3 based on the detection value of the temperature sensor 6, estimates the temperature of the oxidation catalyst 3 based on the detection value of the temperature sensor 7, and Based on the detected value, the temperature of the filter 4 can be estimated. Further, the ECU 20 can grasp the PM accumulation state in the filter 4 based on the detection value of the differential pressure sensor 8, and the processing will be described later.

  In the exhaust emission control device of the internal combustion engine 1 configured as described above, roughly, PM (particulate matter) contained in the exhaust is collected by the filter 4 and is suppressed from being released to the outside. In addition, an exhaust purification catalyst (such as a NOx purification catalyst) (not shown) may be provided. Here, when PM collected by the filter 4 is accumulated up to the limit collection amount in the filter 4, the back pressure in the exhaust passage 2 rises, so that it is oxidized and removed by a method such as raising the exhaust temperature, and the filter 4 The collection ability is regenerated. In the present specification, the process for regeneration of the collection ability is referred to as “filter regeneration process”. Specifically, in the filter regeneration process, a predetermined amount of fuel is supplied into the exhaust gas from the fuel supply valve 5 and burned by the oxidation catalyst 3, whereby the exhaust gas temperature is raised and thereby accumulated on the filter. PM is removed by oxidation.

  By performing the filter regeneration process in a timely manner as described above, the PM trapping ability of the filter is maintained, and a large amount of PM in the exhaust gas is prevented from being released to the outside while suitably maintaining the operating state of the internal combustion engine. It becomes possible. Here, paying attention to the oxidation catalyst 3, since the oxidation catalyst 3 is disposed upstream of the filter 4, it is not originally intended to collect PM, but in particular to the exhaust inflow side of the oxidation catalyst 3. PM is likely to be clogged due to the accumulation of PM on the end face of the substrate. Such clogging at the exhaust inflow side end surface becomes a resistance against the exhaust flow in the exhaust passage 2, and therefore it is necessary to appropriately eliminate clogging at the exhaust inflow side end surface of the oxidation catalyst 3.

Therefore, in the exhaust emission control device for the internal combustion engine 1 according to the present invention, the regeneration control shown in FIG. 2 is executed. The regeneration control is control that is repeatedly executed when a predetermined control program is executed in the ECU 20. First, in S101, a PM emission amount X1, which is a PM amount in the exhaust discharged from the internal combustion engine 1, is calculated. The PM emission amount is an integrated value of the emission amount after the start of the regeneration control. Specifically, based on the engine speed of the internal combustion engine 1 detected by the crank position sensor 11 and the engine load of the internal combustion engine 1 detected by the accelerator opening sensor 12 (or the fuel injection amount in the internal combustion engine 1). Thus, the PM amount in the exhaust gas at the present time is calculated. Note that the correlation between the engine speed and the engine load and the PM amount is measured in advance through experiments or the like, and the correlation is stored in the memory in the ECU 20 in the form of a control map, thereby allowing access to the control map. The calculation is executed. Further, since the amount of PM in the exhaust gas depends on the amount of intake air in the combustion chamber of the internal combustion engine 1, the calculated PM emission amount is corrected based on the amount of intake air by the air flow meter 10, and the corrected PM emission amount is reduced. The final PM emission amount X1 is obtained by adding to the PM emission amount calculated in the process of S101 up to the previous time, that is, by integrating the corrected PM emission amount. When the process of S101 ends, the process proceeds to S102.

In S102, the PM accumulation amount X2 accumulated in the entire filter 4 is calculated based on the exhaust pressure difference between the upstream side and the downstream side of the filter 4 detected by the differential pressure sensor 8. Here, in the relationship between the PM accumulation amount in the filter 4 and the exhaust pressure difference, the exhaust pressure difference tends to increase as the PM accumulation amount increases. The exhaust pressure difference tends to increase as the exhaust flow rate flowing in increases. Further, it is known that the exhaust flow rate in the filter 4 depends on the exhaust temperature. Therefore, in calculating the PM accumulation amount X2, the exhaust pressure difference is corrected according to the following equation 1 in consideration of the dependency between the exhaust flow rate and the exhaust temperature.
Corrected exhaust pressure difference = detected exhaust pressure difference / (exhaust flow rate * (exhaust temperature / 573))
Here, the “exhaust flow rate” is a value obtained by adding the fuel injection amount provided for combustion in the internal combustion engine 1 to the intake air flow rate detected by the air flow meter 10, and its unit is g / s. The “exhaust temperature” uses the temperature of the filter 4 calculated based on the detection value of the temperature sensor 9, and its unit is K.

  By following Formula 1, the exhaust pressure difference detected by the differential pressure sensor 8 is calculated based on the current exhaust flow rate, and the internal temperature of the filter 4, which is a typical state during normal operation of the internal combustion engine 1, is 300 degrees Celsius (573 K). ), It is replaced with a corrected exhaust pressure difference corresponding to the detected pressure difference per unit flow rate. The corrected exhaust pressure difference is an exhaust pressure difference that excludes the influence on the exhaust pressure difference due to the change in the operating state of the internal combustion engine 1 and accurately reflects the PM accumulation amount.

  Based on the above-described corrected exhaust pressure difference, the PM accumulation amount in the filter 4 is calculated through a control map showing the correlation between the corrected exhaust pressure difference and the PM accumulation amount shown in FIG. The control map shown in FIG. 3 is obtained by measuring the correlation between the corrected exhaust pressure difference and the PM accumulation amount in advance by experiments or the like, and storing the correlation in the memory in the ECU 20 in the form of a control map. When the process of S102 ends, the process proceeds to S103.

  In S103, it is determined whether or not the PM accumulation amount X2 calculated in S102 is equal to or greater than the PM amount X0 that is a threshold for performing a normal filter regeneration process. The normal filter regeneration process is a regeneration process for removing PM, which is performed on the filter 4 that can be regarded as a state in which PM is accumulated in the entire filter 4 and its PM collection capability is reduced. is there. Accordingly, as the threshold value X0, a deposition amount that is determined to recover the PM trapping capacity by performing the removal process of the deposited PM after assuming the PM deposition state in the typical filter 4 is set. Become. If a positive determination is made in S103, the process proceeds to S104, and if a negative determination is made, the process proceeds to S105.

  In the normal filter regeneration process in S104, until the exhaust temperature flowing into the filter 4, that is, the exhaust temperature detected by the temperature sensor 7, reaches a temperature at which the PM accumulated on the filter 4 can be oxidized and removed. Fuel is added to the exhaust by the fuel supply valve 5. The fuel added to the exhaust is oxidized by the oxidation catalyst 3 to raise the exhaust temperature. The amount of fuel added by the fuel supply valve 5 is determined based on the temperature difference between the exhaust temperature detected by the temperature sensor 6 and the exhaust temperature to be reached for PM oxidation removal.

If a negative determination is made in S103, the process of the reproduction control proceeds to S105. In S105, the clogging rate (hereinafter referred to as “end-face clogging rate”) Rp at the exhaust inflow end surface of the oxidation catalyst 3 is calculated. This end face clogging rate Rp is defined as the occupancy rate of the deposited PM in the space volume into which exhaust can flow at the exhaust inflow side end face of the oxidation catalyst 3, and the exhaust enters the oxidation catalyst 3 as the end face clogging rate Rp increases. As a result, the back pressure in the exhaust passage 2 increases. When no PM is deposited on the exhaust inflow side end face of the oxidation catalyst 3, the end face clogging rate is 0%, and PM accumulation on the exhaust inflow side end face of PM proceeds and the end face clogging rate Rp is 100%. Then, it means reaching a completely closed state.

  Specifically, based on the difference amount (X1-X2) between the PM emission amount X1 calculated in S101 and the PM deposition amount X2 calculated in S102, the difference amount and the end face shown in FIG. The end face clogging rate Rp is calculated through a control map showing a correlation with the clogging rate Rp. The control map shown in FIG. 4 is obtained by measuring the correlation between the difference amount and the end face clogging rate Rp in advance through experiments or the like, and storing the correlation in the memory of the ECU 20 in the form of a control map. In the oxidation catalyst 3, when PM is accumulated on the end face on the exhaust inflow side, PM that should be collected by the filter 4 is collected in the oxidation catalyst, and the amount of PM discharged from the internal combustion engine 1 is increased. There is a deviation between X1 and the amount of PM deposited on the filter 4. The difference between the PM discharge amount and the PM accumulation amount appears as the difference amount X1-X2. Therefore, in S105, the end face clogging rate Rp can be reasonably calculated by accessing the control map shown in FIG. 4 based on the difference amount.

  In the control map shown in FIG. 4, when the difference amount exceeds a certain level, it is clear that the end face clogging rate Rp tends to increase as the difference amount increases. This is because, in the initial stage where PM is not collected so much in the oxidation catalyst 3, PM is also in a state where it tends to flow downstream on the exhaust flow, but PM is collected and deposited on the end face of the exhaust inflow side. Since the PM easily accumulates on the end face as the engine speed increases, it is considered that the end face clogging rate Rp is increased as the PM discharge amount from the internal combustion engine 1 increases and the difference amount increases. When the process of S105 ends, the process proceeds to S106.

  In S106, whether or not the end face clogging rate Rp calculated in S105 is equal to or higher than Rp0, which is a threshold value for performing a regeneration process (oxidation catalyst regeneration process) for eliminating the clogged state in the oxidation catalyst 3. Is determined. The oxidation catalyst regeneration process is a regeneration in which PM is deposited on the exhaust inflow side end surface of the oxidation catalyst 3 and the temperature of the oxidation catalyst 3 is increased to remove the deposited PM in a state where the exhaust does not easily flow into the interior. It is processing. Therefore, the threshold Rp0 is assumed to be a PM accumulation state on the exhaust inflow side end face of the oxidation catalyst 3, and the fuel added to the exhaust from the fuel supply valve 5 reaches the oxidation catalyst 3, where it is used for the oxidation reaction. It will be set to be able to. For example, if the threshold value Rp0 is set to a relatively high value, the oxidation catalyst regeneration process is performed in a state in which the exhaust gas containing the added fuel hardly flows inside the oxidation catalyst 3, thereby effectively eliminating clogging. It becomes difficult. Therefore, it is preferable to set the threshold value Rp0 from the viewpoint of efficiently eliminating clogging. If an affirmative determination is made in S106, the process proceeds to S107, and if a negative determination is made, the processing from S101 onward is repeated again.

  In S107, an oxidation catalyst regeneration process is executed. The oxidation catalyst regeneration process is performed mainly for the purpose of removing PM deposited on the exhaust inflow side end face of the oxidation catalyst 3. Specifically, the fuel addition from the fuel supply valve 5 is controlled so that the temperature of the oxidation catalyst 3 reaches a temperature (for example, 500 degrees) necessary for oxidizing and removing the PM accumulated therein. . In this case, the exhaust temperature flowing into the filter 4 is also raised, and the PM deposited on the filter 4 is removed by oxidation. Therefore, the process of S107 is performed until the clogging on the exhaust inflow side end face of the oxidation catalyst 3 is eliminated and the accumulated PM of the filter 4 is completely removed by oxidation.

  When the process of S107 ends, the reproduction control ends. At this time, the clogging of the end face of the oxidation catalyst 3 is eliminated, and the accumulated PM of the filter 4 is oxidized and removed. Therefore, parameters relating to the normal filter regeneration process and the oxidation catalyst regeneration process (PM discharge amount X1, PM deposition amount X2). The end face clogging rate Rp) is reset.

<Other examples>
The control shown in FIG. 2 performed in the exhaust emission control device for the internal combustion engine 1 according to the present invention includes regeneration processes (the process of S104 and the process of S107) related to the oxidation catalyst 3 and the filter 4, and these regeneration processes are performed. Of course, an exhaust purification device that performs only control for calculating the clogging rate Rp at the exhaust inflow side end face of the oxidation catalyst 3 also belongs to the category of the present invention.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust passage 3 Oxidation catalyst 4 Filter 5 Fuel supply valve 6, 7, 9 Exhaust temperature sensor 8 Differential pressure sensor 10 Air flow meter 11 Crank position sensor 12 Accelerator opening sensor 13 Intake passage 20 ECU

Claims (1)

A filter provided in an exhaust passage of the internal combustion engine for collecting particulate matter in the exhaust;
An oxidation catalyst provided in the exhaust passage upstream of the filter;
Based on the engine rotational speed of the internal combustion engine, the engine load in the internal combustion engine, and the intake air amount, a PM emission amount that is an integrated amount of particulate matter contained in the exhaust gas discharged from the internal combustion engine and flowing into the filter is calculated. A first calculation unit;
A PM deposition amount, which is a deposition amount of particulate matter collected in the filter, is calculated based on an exhaust pressure difference between the upstream side and the downstream side of the filter, and a flow rate and temperature of exhaust gas flowing into the filter. A calculation unit;
Based on the difference between the PM emission amount calculated by the first calculation unit and the PM deposition amount calculated by the second calculation unit, the clogging rate at the end face on the exhaust inflow side of the oxidation catalyst. A third calculation unit for calculating an end face clogging rate;
An exhaust purification device for an internal combustion engine, comprising:

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