JP2005083273A - Exhaust gas purification system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a PM accumulation amount of a filter with high accuracy in an internal combustion engine provided with a filter for collecting PM in exhaust gas in an exhaust passage.
SOLUTION: Based on the first accumulation amount estimation means for estimating the PM accumulation amount when the filter regeneration process is not performed, and the temperature of the exhaust gas flowing out from the filter when the filter regeneration process is performed. A second accumulation amount estimating means for estimating the PM accumulation amount, and the PM accumulation amount estimated by the first accumulation amount estimation means according to the PM accumulation amount estimated by the second accumulation amount estimation means. Correction is performed (S105 to S107).
[Selection] Figure 2

Description

  The present invention relates to an exhaust gas purification system for an internal combustion engine having a filter for collecting particulate matter in exhaust gas in an exhaust passage.

In an internal combustion engine equipped with an exhaust passage with a filter that collects particulate matter (hereinafter referred to as PM) in the exhaust, when the engine is decelerated, the EGR valve is opened at a predetermined opening, and the amount of fresh air is detected. A technique for estimating the amount of PM deposited on the filter (hereinafter referred to as PM deposition amount) from the detected amount of fresh air is disclosed (for example, refer to Patent Document 1). Further, there is a technique for determining that the PM accumulation amount is abnormal when the difference between the PM accumulation amount calculated from the operating state of the internal combustion engine and the PM accumulation amount calculated from the differential pressure of the exhaust before and after the filter is large. (For example, refer to Patent Document 2).
JP 2002-289234 A JP 7-317529 A Japanese Patent Laid-Open No. 3-11142

  In an internal combustion engine provided with a filter for collecting PM in exhaust gas in an exhaust passage, a filter regeneration process for oxidizing and removing the accumulated PM by raising the temperature of the filter is performed. When such a filter regeneration process is executed, if the PM accumulation amount is excessive, the temperature of the filter may be excessively increased, and the thermal deterioration of the filter may be promoted or the filter may be melted.

  The present invention has been made in view of the above problems, and in an internal combustion engine provided with a filter for collecting PM in exhaust gas in an exhaust passage, it is possible to detect the PM accumulation amount of the filter with higher accuracy. The issue is to provide technology.

  In the present invention, the following means are adopted in order to solve the above problems.

  That is, according to the present invention, the filter regeneration process is performed using the PM accumulation amount estimated when the filter regeneration process is not performed and the PM accumulation amount estimated when the filter regeneration process is performed. If there is a difference between the two, the PM accumulation amount estimated when the filter regeneration process is not performed according to the PM accumulation amount estimated when the filter regeneration process is performed Is to correct.

More specifically, the exhaust gas purification system for an internal combustion engine according to the present invention is:
A filter provided in the exhaust passage and collecting particulate matter in the exhaust;
First accumulation amount estimation means for estimating the amount of particulate matter deposited on the filter when particulate matter is not removed from the filter;
When the deposition amount of the particulate matter estimated by the first deposition amount estimation means becomes equal to or greater than a specified amount, the particulate matter deposition amount estimated by the first deposition amount estimation means depends on the deposition amount of the particulate matter. In an exhaust gas purification system for an internal combustion engine, comprising: a filter regeneration means that raises the temperature of the filter and oxidizes and removes particulate matter deposited on the filter.
Second deposition for estimating the amount of particulate matter deposited on the filter based on the temperature of the exhaust gas flowing out from the filter when the particulate matter is removed from the filter by the filter regeneration means. A quantity estimation means;
When the particulate matter is removed from the filter by the filter regeneration means,
The particulate matter deposition amount estimated by the first deposition amount estimation unit and the particulate matter deposition amount estimated by the second deposition amount estimation unit are compared, and the first deposition amount estimation unit is compared. When the amount of particulate matter deposited estimated by the second deposition amount estimation means is larger than the amount of particulate matter deposited estimated by the above, the particles estimated by the first deposition amount estimation means The amount of particulate matter deposited is corrected by increasing the amount, while the amount of particulate matter deposited estimated by the second deposition amount estimating means is greater than the amount of particulate matter deposited estimated by the first deposition amount estimating means. If the amount is smaller, estimated deposition amount correction means for reducing the particulate matter deposition amount estimated by the first deposition amount estimation means is further provided, and
When the estimated deposition amount correcting means corrects the particulate matter deposition amount estimated by the first deposition amount estimating means, the particulate matter deposition amount estimated by the first deposition amount estimating means. And the correction amount is increased as the difference between the deposition amount of the particulate matter estimated by the second deposition amount estimation means is larger.

  Here, the prescribed amount is an amount that is smaller than a PM accumulation amount that may cause the filter to overheat due to heat generated during PM oxidation when the filter regeneration process is performed, and is a predetermined amount. It is.

  In the present invention, when the PM accumulation amount estimated by the first accumulation amount estimation means (hereinafter referred to as the first estimated PM accumulation amount) becomes equal to or greater than a specified amount, the filter regeneration process is executed by the filter regeneration means. The Here, for example, when the first accumulation amount estimation means estimates the PM accumulation amount from the differential pressure of the exhaust before and after the filter (hereinafter referred to as the differential pressure before and after the filter), there are many in the vicinity of the outer periphery of the filter. When the amount of PM deposited is small and the amount of PM deposited near the center axis of the filter is small, the change in pressure occurring before and after the filter is small, and there is a risk of an error between the first estimated PM deposition amount and the actual PM deposition amount. is there. In addition, when the first accumulation amount estimation means estimates the PM accumulation amount from the operation state of the internal combustion engine using a map or the like, the accumulation is performed from the normal map or the like when the operation state of the internal combustion engine becomes a transient operation. Since the amount cannot be estimated, an error may occur between the first estimated PM deposition amount and the actual PM deposition amount as described above. Therefore, the actual PM deposition amount when the filter regeneration process is performed may be larger or smaller than the first estimated PM deposition amount.

  At this time, the filter regeneration process is performed according to the first estimated PM accumulation amount. Therefore, if the filter regeneration process is performed in a state where the actual PM accumulation amount is larger than the first estimated PM accumulation amount, the temperature of the filter increases excessively. There is a risk of doing. On the other hand, if the filter regeneration process is performed in a state where the actual PM accumulation amount is smaller than the first estimated PM accumulation amount, the execution time of the filter regeneration process may be longer than necessary.

  Therefore, in the present invention, when the filter regeneration process is performed, the PM accumulation amount estimated by the second accumulation amount estimation means (hereinafter referred to as the first accumulation amount) that estimates the PM accumulation amount based also on the temperature of the exhaust gas flowing out from the filter. 2 is referred to as an estimated PM accumulation amount), the first estimated PM accumulation amount is corrected.

  When the filter regeneration process is performed, the PM deposited on the filter is oxidized, and a heat amount corresponding to the actual PM deposition amount is generated. For this reason, the temperature of the exhaust gas discharged from the filter rises due to the amount of heat. Accordingly, the temperature of the exhaust gas discharged from the filter becomes a temperature corresponding to the actual PM deposition amount, and the PM deposition amount can be estimated from this temperature. Further, the error between the second estimated PM deposition amount and the actual PM deposition amount is smaller than the error between the first estimated PM deposition amount and the actual PM deposition amount.

In the present invention, when the first estimated PM deposition amount is corrected, if the second estimated PM deposition amount is larger than the first estimated PM deposition amount, the first estimated PM deposition amount is increased and corrected, while the second estimated PM deposition amount is corrected. When the PM accumulation amount is smaller than the first estimated PM accumulation amount, the first estimated PM accumulation amount is corrected to decrease. At this time, the correction amount is increased as the difference between the first estimated PM deposition amount and the second estimated PM deposition amount is larger.

  According to the present invention, the PM accumulation amount of the filter can be detected with higher accuracy by correcting the first estimated PM accumulation amount according to the second estimated PM accumulation amount. As a result, the excessive temperature rise of the filter during the filter regeneration process can be suppressed, and the time required for the filter regeneration process can be made more suitable. Furthermore, by correcting the first estimated PM accumulation amount, it is possible to make the next filter regeneration process start time more suitable.

  In the present invention, the first accumulation amount estimation means is other than a differential pressure sensor that detects the differential pressure before and after the filter, such as one that estimates the PM accumulation amount by a map or the like from the operating state of the internal combustion engine. Furthermore, a differential pressure sensor for detecting the differential pressure before and after the filter may be provided separately from the first accumulation amount estimating means. In such a case, if the PM accumulation amount is estimated from both the operating state of the internal combustion engine and the differential pressure before and after the filter detected by the differential pressure sensor, the PM accumulation amount can be estimated with higher accuracy. In such a case, it is important to detect a failure of the differential pressure sensor.

  Therefore, in the present invention, the first accumulation amount estimation means is other than the differential pressure sensor that detects the differential pressure before and after the filter, and a differential pressure sensor that detects the differential pressure before and after the filter is provided separately from the first accumulation amount estimation means. When the second estimated PM accumulation amount is larger than the first estimated PM accumulation amount and the first estimated PM accumulation amount is corrected to be increased, when the correction amount is equal to or greater than the specified correction amount, An over-deposition determination unit that determines that PM has been over-deposited on the filter is provided. When the over-deposition determination unit determines that PM has over-deposited on the filter, the output value of the differential pressure sensor is If the value does not correspond to when it is excessively deposited, it may be determined that the differential pressure sensor has failed.

  If there is an error between the first estimated PM accumulation amount and the actual PM accumulation amount, and the filter regeneration process is performed in a state where PM is excessively accumulated on the filter, the amount of heat generated during PM oxidation increases rapidly. The discharged temperature also rises rapidly. Along with this, the second estimated PM deposition amount increases rapidly, so the correction amount when the first estimated PM deposition amount is corrected to increase is increased.

  Here, the specified correction amount is a threshold value that can be used to determine that PM has excessively accumulated in the filter when the correction amount when the first estimated PM accumulation amount is increased is equal to or greater than the specified correction amount. This is an experimentally determined value.

  Therefore, if the correction amount when the first estimated PM accumulation amount is corrected to increase is equal to or greater than the specified correction amount, it can be determined that PM has excessively accumulated on the filter. At this time, the output value of the differential pressure sensor is Can be determined as a failure of the differential pressure sensor.

  In the present invention, when the second estimated PM accumulation amount is larger than the first estimated PM accumulation amount, and the first estimated PM accumulation amount is corrected to be increased, the correction amount is equal to or greater than the specified correction amount. In the case of further comprising overdeposition determination means for determining that PM has been excessively deposited, if the overdeposition determination means determines that PM has been excessively deposited on the filter, the temperature rise of the filter may be suppressed.

  As described above, when the filter regeneration process is performed in a state where PM is excessively deposited on the filter, the temperature of the filter rapidly increases. Therefore, if the filter regeneration process is continued as it is, the filter is excessively heated. There is a risk of warming.

  According to the control as described above, when it is determined that the PM is excessively deposited on the filter when the filter regeneration process is performed, the filter temperature rise is suppressed by suppressing the temperature rise of the filter. Can be suppressed.

  The control for suppressing the temperature rise of the filter includes, for example, control for reducing the amount of fuel (reducing agent) supplied to the cylinder or the exhaust passage in order to raise the temperature of the filter, and control for increasing the flow rate of the exhaust gas. Etc. can be illustrated. In addition, since such control is performed when the PM accumulation amount is large, it is preferable to increase the execution time of the filter regeneration process.

  According to the exhaust gas purification system for an internal combustion engine according to the present invention, the PM accumulation amount of the filter can be detected with higher accuracy in the internal combustion engine provided with the filter for collecting PM in the exhaust gas in the exhaust passage. As a result, the excessive temperature rise of the filter during the filter regeneration process can be suppressed, and the execution time of the filter regeneration process can be made more suitable.

  Hereinafter, specific embodiments of an exhaust gas purification system for an internal combustion engine according to the present invention will be described with reference to the drawings.

<Schematic configuration of internal combustion engine and its exhaust system and control system>
First, Embodiment 1 of an exhaust gas purification system for an internal combustion engine according to the present invention will be described. Here, the case where the present invention is applied to a diesel engine for driving a vehicle will be described as an example. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 1 according to the present embodiment and its exhaust system and control system.

  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, and a particulate filter 3 (hereinafter simply referred to as a filter 3) that collects PM such as soot contained in the exhaust is disposed in the middle of the exhaust passage 2. Is provided. The filter 3 according to this embodiment carries an oxidation catalyst.

  The exhaust passage 2 is provided with an exhaust differential pressure sensor 6 that outputs an electrical signal corresponding to the differential pressure across the filter before and after the filter 3. An exhaust temperature sensor 7 that outputs an electrical signal corresponding to the temperature of the exhaust gas flowing through the exhaust passage 2 is provided in the exhaust passage 2 downstream of the filter 3. In addition, a fuel addition valve 5 is provided in the exhaust passage 2 upstream of the filter 3 to add fuel into the exhaust gas as a reducing agent.

  The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 10 for controlling the internal combustion engine 1. The ECU 10 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver. The ECU 10 is electrically connected to various sensors such as the exhaust differential pressure sensor 6 and the exhaust temperature sensor 7, and output signals from the various sensors are input to the ECU 10. The ECU 10 is electrically connected to the fuel addition valve 5, the fuel injection valve of the internal combustion engine 1, and the like, and can control them.

<Filter regeneration control 1>
Next, filter regeneration control for performing filter regeneration processing in the present embodiment will be described. 2 and 3 are flowcharts showing a filter regeneration control routine according to this embodiment. This routine is executed every predetermined time during the operation of the internal combustion engine 1, and is stored in the ECU 10 in advance.

  First, in this routine, in S101, the ECU 10 calculates a first estimated PM accumulation amount that is a PM accumulation amount estimated when the filter regeneration process is not performed. Here, as a method of calculating the first estimated PM accumulation amount, (1) the PM emission amount from the internal combustion engine 1 is derived from a map based on the operating state (engine speed, engine load) of the internal combustion engine 1, Examples include a method of calculating by integrating the derived PM discharge amount, and (2) a method of calculating from the differential pressure across the filter detected by the exhaust differential pressure sensor 6. Moreover, you may calculate by both (1) and (2).

  Next, the ECU 10 proceeds to S102 and determines whether or not the first estimated PM accumulation amount is equal to or greater than a specified amount. The specified amount here is an amount smaller than the PM accumulation amount that may cause the filter 3 to overheat due to heat generated during PM oxidation when the filter regeneration process is performed. Amount. If an affirmative determination is made in S102, the ECU 10 proceeds to S103, and if a negative determination is made, the ECU 10 once ends the execution of this routine.

  In S103, the ECU 10 executes the temperature regeneration control of the filter 3 to execute the filter regeneration process. The temperature increase control of the filter 3 includes (1) adding fuel into the exhaust gas from the fuel addition valve 5, (2) retarding the fuel injection timing in the internal combustion engine 1, and (3) in the internal combustion engine 1. Examples of the control include performing sub fuel injection for injecting fuel at a time other than the main fuel injection.

  Next, the ECU 10 proceeds to S104, and calculates a second estimated PM deposition amount that is a PM deposition amount estimated when the filter regeneration process is being performed. At this time, the second estimated PM accumulation amount is calculated from the exhaust gas temperature detected by the exhaust gas temperature sensor 7.

  Next, the ECU 10 proceeds to S105 and determines whether or not the second estimated PM accumulation amount is larger than the first estimated PM accumulation amount. If an affirmative determination is made in S105, the ECU 10 proceeds to S106, and if a negative determination is made, the ECU 10 proceeds to S111.

  In S106, the ECU 10 calculates an increase correction amount for the first estimated PM accumulation amount from the difference between the first estimated PM accumulation amount and the second estimated PM accumulation amount.

  Next, the ECU 10 proceeds to S107 and corrects the first estimated PM accumulation amount by increasing.

  Next, the ECU 10 proceeds to S108, and determines whether or not the increase correction amount of the first estimated PM accumulation amount is equal to or greater than a specified correction amount. The prescribed correction amount here is a threshold value for determining that PM is excessively deposited on the filter 3 when the correction amount when the first estimated PM accumulation amount is corrected to increase is equal to or greater than the prescribed correction amount. The value is experimentally determined in advance. If an affirmative determination is made in S108, the ECU 10 proceeds to S109, and if a negative determination is made, the ECU 10 proceeds to S110.

  In S109, the ECU 10 executes filter temperature increase suppression control that suppresses the temperature increase of the filter 3. Here, as the filter temperature increase suppression control, the temperature increase control of the filter 3 reduces the amount of fuel added to the exhaust in the case of (1) above, and the fuel injection in the internal combustion engine 1 in the case of (2) above. In the case of the above (3), the control for reducing the amount of sub fuel injection in the internal combustion engine 1 can be exemplified. Further, control for increasing the exhaust gas flow rate by increasing the intake air amount may be used. When the filter temperature increase suppression control is executed, the execution time of the filter regeneration process may be increased. The ECU 10 that has executed the filter temperature increase suppression control proceeds to S110.

  In S110, the ECU 10 stores the increase correction amount of the first estimated PM accumulation amount, and temporarily ends the execution of this routine.

  On the other hand, the ECU 10 that has proceeded to S111 determines whether or not the second estimated PM accumulation amount is smaller than the first estimated PM accumulation amount. If an affirmative determination is made in S111, the ECU 10 proceeds to S112, and if a negative determination is made, the ECU 10 determines that there is almost no difference between the first estimated PM accumulation amount and the second estimated PM accumulation amount, and executes this routine. Exit once.

  In S112, the ECU 10 calculates a reduction correction amount for the first estimated PM accumulation amount from the difference between the first estimated PM accumulation amount and the second estimated PM accumulation amount.

  Next, the ECU 10 proceeds to S113 and corrects the first estimated PM accumulation amount by a decrease.

  Next, the ECU 10 proceeds to S114, executes filter temperature increase promotion control for increasing the temperature increase of the filter 3, and shortens the execution time of the filter regeneration process. Here, as the filter temperature increase promotion control, the temperature increase control of the filter 3 increases the amount of fuel added to the exhaust in the case of (1), and the fuel injection in the internal combustion engine 1 in the case of (2). In the case of the above (3), the control for increasing the auxiliary fuel injection amount in the internal combustion engine 1 can be exemplified. Further, control may be performed to reduce the exhaust flow rate by reducing the intake air amount.

  Next, the ECU 10 proceeds to S115, stores the decrease correction amount of the first estimated PM accumulation amount, and once ends the execution of this routine.

  According to the control described above, the PM accumulation amount of the filter 3 can be detected with higher accuracy by correcting the first estimated PM accumulation amount according to the second estimated PM accumulation amount. As a result, the excessive temperature rise of the filter 3 during the filter regeneration process can be suppressed, and the execution time of the filter regeneration process can be made more suitable. Further, the first estimated PM accumulation amount is corrected, the correction amount is stored in the ECU 10 and reflected in the determination of the start time of the next filter regeneration process, so that the next filter regeneration process start time is more suitable. It becomes possible.

  The filter 3 according to the present embodiment may have a configuration in which the filter itself does not carry an oxidation catalyst, and in addition to the filter, an oxidation catalyst is installed on the upstream side as a pre-stage catalyst.

  Next, a second embodiment of the exhaust gas purification system for an internal combustion engine according to the present invention will be described.

  Since the schematic configuration of the internal combustion engine 1 and its exhaust system and control system according to the present embodiment is the same as that of the first embodiment, the description thereof is omitted.

<Filter regeneration control 2>
Here, filter regeneration control for performing filter regeneration processing in the present embodiment will be described. FIG. 4 is a flowchart showing a filter regeneration control routine according to the present embodiment. Note that the steps after A in FIG. 4 are the same as those in the flowchart of FIG. Also, in the other steps, the same numbers are assigned to the same contents as those in the first embodiment, and the description thereof is omitted. This routine is executed every predetermined time during the operation of the internal combustion engine 1, and is stored in the ECU 10 in advance.

  First, in this routine, in S201, the ECU 10 derives the PM emission amount from the internal combustion engine 1 from a map based on the operating state (engine speed, engine load) of the internal combustion engine 1, and this derived PM emission amount. Is accumulated to calculate the first estimated PM deposition amount. The ECU 10 having calculated the first estimated PM accumulation amount proceeds to S102, and performs the processing after S102 in the same manner as in the first embodiment.

  If an affirmative determination is made in S108, that is, if the increase correction amount of the first estimated PM accumulation amount is determined to be equal to or greater than the specified correction amount, the ECU 10 proceeds to S208.

  In S208, the ECU 10 reads the output value of the differential pressure sensor 6, and determines whether or not the output value is a value corresponding to when PM is excessively deposited on the filter. If an affirmative determination is made in S208, the ECU 10 proceeds to S110, and if a negative determination is made, the ECU 10 proceeds to S209.

  In S108, when the increase correction amount of the first estimated PM accumulation amount is determined to be equal to or greater than the specified correction amount, it can be determined that PM has excessively accumulated on the filter. Therefore, when it is determined in S208 that the output value of the differential pressure sensor 6 does not correspond to a value when PM is excessively deposited on the filter, it can be determined that the differential pressure sensor 6 has failed. Therefore, in S209, the ECU 10 determines that the differential pressure sensor 6 has failed, and proceeds to S110.

  According to the control as described above, the PM accumulation amount of the filter 3 can be detected with higher accuracy, and further, the failure of the differential pressure sensor 6 can be detected.

The figure which shows schematic structure of the exhaust system and control system with the internal combustion engine which concerns on this invention. FIG. 3 is a flowchart showing a part of a filter regeneration control routine according to the first embodiment. FIG. 3 is a flowchart showing a part of a filter regeneration control routine according to the first embodiment. FIG. 9 is a flowchart showing a part of a filter regeneration control routine according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Exhaust passage 3 ... Filter 5 ... Fuel addition valve 6 ... Exhaust differential pressure sensor 7 ... Exhaust temperature sensor 10 ... ECU

Claims (3)

A filter provided in the exhaust passage and collecting particulate matter in the exhaust;
First accumulation amount estimation means for estimating the amount of particulate matter deposited on the filter when particulate matter is not removed from the filter;
When the deposition amount of the particulate matter estimated by the first deposition amount estimation means becomes equal to or greater than a specified amount, the particulate matter deposition amount estimated by the first deposition amount estimation means depends on the deposition amount of the particulate matter. In an exhaust gas purification system for an internal combustion engine, comprising: a filter regeneration means that raises the temperature of the filter and oxidizes and removes particulate matter deposited on the filter.
Second deposition for estimating the amount of particulate matter deposited on the filter based on the temperature of the exhaust gas flowing out from the filter when the particulate matter is removed from the filter by the filter regeneration means. A quantity estimation means;
When the particulate matter is removed from the filter by the filter regeneration means, the particulate matter accumulation amount estimated by the first accumulation amount estimation means and the second accumulation amount estimation means are estimated. The particulate matter deposition amount estimated by the second deposition amount estimation unit is compared with the particulate matter deposition amount estimated by the first deposition amount estimation unit. If the amount is larger, the particulate matter deposition amount estimated by the first deposition amount estimation means is corrected to be increased, while the particulate matter deposition estimated by the first deposition amount estimation means. If the amount of particulate matter deposited estimated by the second deposition amount estimating means is smaller than the amount, the particulate matter deposited amount estimated by the first deposition amount estimating means is reduced and corrected. Estimated deposit A positive means, further comprising a
When the estimated deposition amount correcting means corrects the particulate matter deposition amount estimated by the first deposition amount estimating means, the particulate matter deposition amount estimated by the first deposition amount estimating means. An exhaust gas purification system for an internal combustion engine, wherein the correction amount is increased as the difference between the particulate matter accumulation amount estimated by the second accumulation amount estimation means increases. The first accumulation amount estimation means is other than a differential pressure sensor that detects a differential pressure of exhaust before and after the filter,
Separately from the first accumulation amount estimating means, a differential pressure sensor provided in an exhaust passage for detecting a differential pressure of exhaust before and after the filter;
The particulate matter deposition amount estimated by the second deposition amount estimation unit is larger than the particulate matter deposition amount estimated by the first deposition amount estimation unit, and the estimated deposition amount correction unit When the amount of accumulated particulate matter estimated by the first amount-of-deposition estimation means is corrected to be increased, if the amount of correction is equal to or greater than a specified correction amount, it is determined that particulate matter has been excessively deposited on the filter. Overdeposition determination means to
When it is determined by the over-deposition determination means that particulate matter has been over-deposited on the filter, the output value of the differential pressure sensor becomes a value corresponding to when particulate matter has over-deposited on the filter. If not, a differential pressure sensor failure determination means for determining a failure of the differential pressure sensor,
The exhaust gas purification system for an internal combustion engine according to claim 1, further comprising: The particulate matter deposition amount estimated by the second deposition amount estimation unit is larger than the particulate matter deposition amount estimated by the first deposition amount estimation unit, and the estimated deposition amount correction unit When the amount of accumulated particulate matter estimated by the first amount-of-deposition estimation means is corrected to be increased, if the amount of correction is equal to or greater than a specified correction amount, it is determined that particulate matter has been excessively deposited on the filter. Overdeposition determination means to
When it is determined by the over-deposition determination means that particulate matter has been over-deposited on the filter, the temperature increase suppression means for suppressing the temperature increase of the filter;
The exhaust gas purification system for an internal combustion engine according to claim 1, further comprising:

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