JP2003286907A - Internal combustion engine abnormality determination method and apparatus - Google Patents

Abstract

(57) Abstract: In an internal combustion engine, EGR is performed using a pressure sensor.
An open / close abnormality of the valve and the intake throttle valve is determined. In an internal combustion engine (1) for reducing NOx by supplying a reducing agent to a particulate filter (12) carrying a storage reduction type NOx catalyst, a change in pressure upstream of the particulate filter (12) during reduction of NOx causes EGR.
An abnormality determination method for the internal combustion engine that determines whether the valve 15 or the intake throttle valve 7 is open or closed is employed. When the EGR valve 15 or the intake throttle valve 7 is opened or closed, the flow rate of the exhaust gas changes and the pressure upstream of the filter changes. Thus, since there is a correlation between the opening and closing of the EGR valve 15 or the intake throttle valve 7 and the pressure upstream of the filter 12, it is determined whether the EGR valve 15 or the intake throttle valve 7 is abnormally open or closed based on the pressure upstream of the filter 12. It is possible to do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality determining method and apparatus for an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, in order to suppress the generation of NOx itself, an EGR device is used which connects an exhaust system and an intake system and recirculates exhaust gas. In the EGR device, the recirculation amount of exhaust gas can be adjusted by opening and closing the EGR valve, and an appropriate amount of exhaust gas can be recirculated according to the operating state to suppress the generation of NOx.

In such an internal combustion engine, the intake throttle valve or the EGR valve may be stuck or the operating range may be restricted due to the adhesion of PM or the like contained in the exhaust gas. In such a state, there is a risk that the amount of NOx released and the amount of PM generated will increase.

To solve such a problem, for example, Japanese Patent Publication No.
In Japanese Patent Laid-Open No. 31572, the EGR valve is temporarily closed while the valve is opened according to the engine operating state, and the change in the intake air amount at that time is detected by an air flow meter, and the change amount is within a predetermined range. If it is within the range, it is determined that the EGR valve is abnormal.

On the other hand, in Japanese Patent Laid-Open No. 7-166971, when the deviation between the intake air amount detected by the air flow meter and the target intake air amount obtained from the engine operating state is outside a predetermined range, the intake throttle valve malfunctions. It has been determined.

[0006]

However, in each of the inventions described in the above publications, it is necessary to detect the intake air amount by an air flow meter or the like, but the air flow meter or the like is provided in all internal combustion engines. is not. Further, in the invention described in Japanese Patent Publication No. 6-31572, the EGR valve is forcedly opened and closed, which may affect the operating state.

The present invention has been made in view of the above problems, and provides a technique capable of determining whether the EGR valve and the intake throttle valve are open / closed abnormally by using a pressure sensor in an internal combustion engine. The purpose is to

[0008]

In order to achieve the above object, the internal combustion engine of the present invention employs the following method. That is,
According to a first aspect of the present invention, in an internal combustion engine that supplies a reducing agent to a particulate filter carrying a NOx storage reduction catalyst to reduce NOx, the EGR valve of the EGR valve changes due to a change in pressure upstream of the particulate filter during NOx reduction. It is characterized in that an abnormality in opening and closing is determined.

When the EGR gas is recirculated, the flow rate of the exhaust gas flowing into the filter is reduced accordingly, so that the pressure upstream of the filter is reduced. As described above, since there is a correlation between the pressure upstream of the filter and the EGR valve opening degree, it is possible to determine whether the EGR valve is normally opened or closed based on the change in the pressure upstream of the filter. Become.

In order to achieve the above object, the internal combustion engine of the present invention employs the following method. That is, the second aspect of the present invention is an internal combustion engine that supplies a reducing agent to a particulate filter carrying an occlusion reduction type NOx catalyst to reduce NOx, in which the pressure difference between the upstream and downstream of the particulate filter at the time of NOx reduction is reduced. It is characterized in that the opening / closing abnormality of the EGR valve is determined based on the change.

When the EGR gas is recirculated, the flow rate of the exhaust gas flowing into the filter is reduced accordingly, so that the pressure difference between the upstream side and the downstream side of the filter becomes small. As described above, since there is a correlation between the pressure difference before and after the filter and the EGR valve opening degree, E is based on the change in the pressure difference before and after the filter.
It becomes possible to judge whether the GR valve is normally opened or closed.

In order to achieve the above object, the internal combustion engine of the present invention employs the following method. That is, a third aspect of the present invention is an internal combustion engine that supplies a reducing agent to a particulate filter carrying an NOx storage reduction catalyst to reduce NOx, and intake air due to a change in pressure upstream of the particulate filter during NOx reduction. It is characterized by determining whether the throttle valve is open or closed abnormally.

When the intake throttle valve is controlled in the closing direction, the flow rate of the exhaust gas flowing into the filter is correspondingly decreased, so that the pressure upstream of the filter is decreased. As described above, since there is a correlation between the pressure upstream of the filter and the opening degree of the intake throttle valve, it can be determined whether or not the intake throttle valve is normally opened / closed based on the change in the pressure upstream of the filter. It will be possible.

In order to achieve the above object, the internal combustion engine of the present invention employs the following method. That is, a fourth aspect of the present invention is an internal combustion engine that supplies a reducing agent to a particulate filter that carries an NOx storage reduction catalyst to reduce NOx, in which the pressure difference between the upstream and downstream pressures of the particulate filter during NOx reduction is reduced. It is characterized in that the opening / closing abnormality of the intake throttle valve is determined based on the change.

When the intake throttle valve is controlled in the valve closing direction, the flow rate of the exhaust gas flowing into the filter is reduced accordingly, so that the pressure difference between the upstream side and the downstream side of the filter becomes small. In this way, since there is a correlation between the pressure difference before and after the filter and the intake throttle opening, it is determined whether the intake throttle valve is normally opened or closed based on the change in the pressure difference before and after the filter. It becomes possible.

In order to achieve the above object, the internal combustion engine of the present invention employs the following means. That is, a fifth aspect of the present invention includes an exhaust gas purification unit that purifies harmful substances contained in exhaust gas, a pressure detection unit that detects the pressure of exhaust gas upstream of the exhaust gas purification unit, and an exhaust system and an intake system of an internal combustion engine. An EGR passage for communicating a part of exhaust gas discharged from the internal combustion engine to the intake system of the internal combustion engine, an EGR valve for adjusting a flow rate of EGR gas flowing in the EGR passage, and an operating state of the internal combustion engine. According to the EGR valve control means for performing opening / closing control of the EGR valve, a pressure estimating means for estimating the pressure of the exhaust gas upstream of the exhaust gas purifying means from the opening degree of the EGR valve targeted by the EGR valve control means, and the pressure Allowable value calculating means for calculating a range of pressure at which the EGR valve can be considered to be normal based on the exhaust pressure estimated by the estimating means, and the allowable value calculation for the value detected by the pressure detecting means. Characterized in that it and a abnormality determining means for determining that the closing abnormality of the EGR valve when it is outside the range of pressure that is calculated by the stage.

The greatest feature of the present invention is that when the EGR gas is recirculated, the flow rate of the exhaust gas decreases accordingly. Therefore, the decrease in the flow rate of the exhaust gas is detected by the pressure detecting means as a change in the exhaust gas pressure. It is to determine whether or not an abnormality has occurred in the EGR valve.

In the internal combustion engine constructed as described above, the EG
When the R valve is opened and the exhaust gas is recirculated to the EGR passage, the amount of the exhaust gas flowing into the exhaust gas purification means is reduced, and the pressure of the exhaust gas upstream of the exhaust gas purification means is reduced. Such changes in pressure are
There is a correlation with the opening degree of the EGR valve. Therefore, the open / closed state of the EGR valve can be estimated by detecting the pressure value before the exhaust gas purification means that changes when the EGR valve is opened / closed, and it is possible to determine whether or not the EGR valve is abnormal. . Incidentally, the exhaust purification means is a particulate filter capable of temporarily collecting particulate matter contained in the exhaust, NOx stored when the air-fuel ratio of the exhaust is lean, and NOx stored in the presence of a reducing agent. Examples thereof include NOx catalysts for reduction and other catalysts having an oxidizing function.

In the present invention, the abnormality determining means is
When the value detected by the pressure detection means is larger than the pressure range calculated by the allowable value calculation means, the opening degree of the EGR valve is smaller than the opening degree requested by the EGR valve control means, On the other hand, when the value detected by the pressure detecting means is smaller than the range of pressure calculated by the allowable value calculating means, the opening degree of the EGR valve is larger than the opening degree requested by the EGR valve control means. It can be determined to be large.

Here, when the EGR valve has an abnormality that it does not open to the required opening degree, the recirculation amount of the exhaust gas decreases with respect to the required value. As a result, the amount of exhaust gas upstream of the exhaust gas purification unit increases, so the pressure of the exhaust gas detected by the pressure detection unit becomes larger than the pressure range calculated by the allowable value calculation unit. Therefore, when the pressure detected by the pressure detecting means is larger than the pressure range calculated by the allowable value calculating means, the abnormality determining means determines that the EGR valve has an abnormality of not opening to the required opening degree. Is possible. On the other hand, when the EGR valve is not closed to the required opening, the exhaust gas recirculation amount increases with respect to the required value. As a result, the amount of exhaust gas upstream of the exhaust gas purification unit decreases, so the pressure of the exhaust gas detected by the pressure detection unit becomes smaller than the pressure range calculated by the allowable value calculation unit. Therefore, when the pressure detected by the pressure detecting means is smaller than the pressure range calculated by the allowable value calculating means, the abnormality determining means determines that the EGR valve has an abnormality that it does not close to the required opening degree. Is possible.

In order to achieve the above object, the internal combustion engine of the present invention employs the following means. That is, a sixth aspect of the invention is an exhaust gas purification means for purifying harmful substances contained in exhaust gas, a differential pressure sensor for detecting a pressure difference between the exhaust gas upstream and downstream of the exhaust gas purification means, an exhaust system of an internal combustion engine, and an intake air. Of the internal combustion engine, an EGR passage for returning a part of exhaust gas discharged from the internal combustion engine to the intake system of the internal combustion engine, an EGR valve for adjusting a flow rate of the EGR gas flowing in the EGR passage, and EG for controlling the opening and closing of the EGR valve according to the operating state
R valve control means and E targeted by the EGR valve control means
It is determined that the EGR valve is normal based on the pressure difference estimation means for estimating the pressure difference between the exhaust gas upstream and downstream of the exhaust gas purification means from the opening degree of the GR valve and the exhaust gas pressure difference estimated by the pressure difference estimation means. A permissible value calculating means for calculating a range of pressure difference that can be performed, and an opening / closing abnormality of the EGR valve when the value detected by the differential pressure sensor is outside the range of the pressure difference calculated by the permissible value calculating means. And an abnormality determination unit that determines that

The greatest feature of the present invention is that when EGR gas is recirculated, the flow rate of exhaust gas decreases accordingly. Therefore, the decrease of the flow rate of exhaust gas is detected by a differential pressure sensor as a change in pressure difference, It is to determine whether or not an abnormality has occurred in the EGR valve.

In the internal combustion engine configured as described above, the EG
When the R valve is opened and the exhaust gas is recirculated to the EGR passage, the amount of the exhaust gas flowing into the exhaust gas purification unit is reduced, and the pressure difference between the exhaust gas upstream and the exhaust gas purification unit is reduced. Such a change in the pressure difference has a correlation with the opening degree of the EGR valve. Therefore, the open / closed state of the EGR valve can be estimated by detecting the pressure difference before and after the exhaust gas purification means that changes when the EGR valve is opened / closed, and it is possible to determine whether or not the EGR valve is abnormal. . Incidentally, the exhaust purification means is a particulate filter capable of temporarily collecting particulate matter contained in the exhaust, NOx stored when the air-fuel ratio of the exhaust is lean, and NOx stored in the presence of a reducing agent. Examples thereof include NOx catalysts for reduction and other catalysts having an oxidizing function.

In the present invention, the abnormality determining means is
When the value detected by the differential pressure sensor is larger than the range of the pressure difference calculated by the allowable value calculation means, the opening degree of the EGR valve is smaller than the opening degree requested by the EGR valve control means. On the other hand, when the value detected by the differential pressure sensor is smaller than the range of the pressure difference calculated by the allowable value calculation means, the opening degree of the EGR valve is the opening degree requested by the EGR valve control means. Can be determined to be greater than.

Here, when the EGR valve has an abnormality that it does not open to the required opening degree, the exhaust gas recirculation amount decreases with respect to the required value. As a result, the amount of exhaust gas upstream of the exhaust gas purification means increases, so that the pressure difference detected by the differential pressure sensor becomes larger than the pressure difference range calculated by the allowable value calculation means. Therefore, when the pressure difference detected by the differential pressure sensor is larger than the pressure difference range calculated by the allowable value calculation means, the abnormality determination means determines that the EGR valve has an abnormality that it does not open to the required opening degree. It becomes possible to judge. On the other hand, when the EGR valve is not closed to the required opening, the exhaust gas recirculation amount increases with respect to the required value. As a result, the amount of exhaust gas on the upstream side of the exhaust gas purification unit decreases, so that the pressure difference detected by the differential pressure sensor becomes smaller than the pressure difference range calculated by the allowable value calculation unit. Therefore, when the pressure difference detected by the differential pressure sensor is smaller than the pressure difference range calculated by the allowable value calculation means, the abnormality determination means determines that the EGR valve is not closed to the required opening degree. It becomes possible to judge.

In the fifth and sixth aspects of the present invention, after the amount of recirculated EGR gas is increased and the amount of soot is maximized, low temperature combustion is performed to further increase the amount of EGR gas and before the amount of EGR gas is increased. The combustion method selection means capable of switching between the normal combustion and the normal combustion is further provided, and the abnormality determination means can perform the abnormality determination when the normal combustion and the low temperature combustion are switched.

In the internal combustion engine configured as described above, when the low temperature combustion is selected by the combustion method selecting means, the recirculation amount of EGR gas is increased. As a result, the amount of exhaust gas flowing into the exhaust gas purification unit decreases, the pressure detected by the pressure detection unit decreases, or the pressure difference before and after the exhaust gas purification unit also decreases. Therefore, it is possible to determine the opening / closing abnormality of the EGR valve based on the pressure detected by the pressure detection means or the pressure difference detected by the differential pressure sensor when the low temperature combustion is selected. Similarly, when the low temperature combustion is switched to the normal combustion, the opening / closing abnormality of the EGR valve can be determined.

In order to achieve the above object, the internal combustion engine of the present invention employs the following means. That is, a seventh aspect of the present invention is an exhaust gas purification means for purifying harmful substances contained in exhaust gas, a pressure detection means for detecting a pressure of exhaust gas upstream of the exhaust gas purification means, and fresh air flowing in an intake system of an internal combustion engine. Of the intake throttle valve, an intake throttle valve control means for controlling the opening and closing of the intake throttle valve according to the operating state of the internal combustion engine, and an opening of the intake throttle valve targeted by the intake throttle valve control means. The pressure estimation means for estimating the pressure of the exhaust gas upstream of the exhaust gas purification means, and the range of the pressure at which the intake throttle valve can be considered normal based on the pressure of the exhaust gas estimated by the pressure estimation means. An allowable value calculating means, and an abnormality determining means for determining that the intake throttle valve is open / closed abnormally when the value detected by the pressure detecting means is outside the range of the pressure calculated by the allowable value calculating means, Be equipped with The features.

The most important feature of the present invention is that when the intake throttle valve is closed, the flow rate of exhaust gas decreases accordingly,
The decrease in the flow rate of the exhaust gas is detected by the pressure detecting means as a change in pressure to determine whether or not an abnormality has occurred in the intake throttle valve.

In the internal combustion engine configured as described above, when the intake throttle valve is closed to reduce the intake air amount, the amount of exhaust gas flowing into the exhaust gas purification means also decreases, and the pressure upstream of the exhaust gas purification means decreases. To do. Such a change in pressure correlates with the opening degree of the intake throttle valve. Therefore, the open / closed state of the intake throttle valve can be estimated by detecting the pressure value before the exhaust purification means that changes when the intake throttle valve is opened / closed, and it can be determined whether or not the intake throttle valve is abnormal. It will be possible. Incidentally, the exhaust purification means is a particulate filter capable of temporarily collecting particulate matter contained in the exhaust, NOx stored when the air-fuel ratio of the exhaust is lean, and NOx stored in the presence of a reducing agent. Examples thereof include NOx catalysts for reduction and other catalysts having an oxidizing function.

In the present invention, the abnormality determining means is
When the value detected by the pressure detecting means is larger than the pressure range calculated by the allowable value calculating means, the opening degree of the intake throttle valve is larger than the opening degree requested by the intake throttle valve control means. On the other hand, when the value detected by the pressure detecting means is smaller than the range of the pressure calculated by the allowable value calculating means, the opening of the intake throttle valve is requested by the intake throttle valve control means. It can be determined that the opening is smaller than the opening.

Here, when an abnormality occurs in which the intake throttle valve does not open to the required opening degree, the intake amount decreases with respect to the required value. As a result, the amount of exhaust gas upstream of the exhaust gas purification unit decreases, so the pressure of the exhaust gas detected by the pressure detection unit becomes smaller than the pressure range calculated by the allowable value calculation unit. Therefore, when the pressure detected by the pressure detecting means is smaller than the pressure range calculated by the allowable value calculating means, the abnormality determining means determines that there is an abnormality that the intake throttle valve does not open to the required opening degree. It becomes possible. On the other hand, when an abnormality occurs in which the intake throttle valve does not close to the required opening, the intake amount increases with respect to the required value. As a result, the amount of exhaust gas upstream of the exhaust gas purification unit increases, so the pressure of the exhaust gas detected by the pressure detection unit is
It becomes larger than the pressure range calculated by the allowable value calculation means.
Therefore, when the pressure detected by the pressure detecting means is larger than the pressure range calculated by the allowable value calculating means, the abnormality determining means determines that there is an abnormality that the intake throttle valve does not close to the required opening degree. It becomes possible.

In order to achieve the above object, the internal combustion engine of the present invention employs the following means. That is, the eighth invention is an exhaust gas purification means for purifying harmful substances contained in the exhaust gas, a differential pressure sensor for detecting a pressure difference between the exhaust gas upstream and downstream of the exhaust gas purification means, and an intake system for the internal combustion engine. An intake throttle valve for adjusting the amount of fresh air to be charged, an intake throttle valve control means for controlling the opening and closing of the intake throttle valve according to the operating state of the internal combustion engine, and an intake throttle target for the intake throttle valve control means. A pressure difference estimating means for estimating the pressure difference between the exhaust gas upstream and downstream of the exhaust gas purifying means from the opening of the valve, and that the intake throttle valve is normal based on the pressure difference between the exhaust gases estimated by the pressure difference estimating means. Allowable value calculating means for calculating the range of pressure difference that can be performed, and opening / closing of the intake throttle valve when the value detected by the differential pressure sensor is outside the range of pressure difference calculated by the allowable value calculating means. Determined to be abnormal A normally determining means, characterized in that it comprises a.

The most important feature of the present invention is that when the intake throttle valve is closed, the flow rate of exhaust gas decreases accordingly,
The decrease in the flow rate of the exhaust gas is detected by the differential pressure sensor as a change in the pressure difference, and it is determined whether or not there is an abnormality in the intake throttle valve.

In the internal combustion engine thus constructed, when the intake throttle valve is closed to reduce the intake air amount, the amount of exhaust gas flowing into the exhaust gas purification means also decreases, and the exhaust gas purification means upstream and downstream. The pressure difference is reduced. Such a change in the pressure difference has a correlation with the opening degree of the intake throttle valve. Therefore, the open / closed state of the intake throttle valve can be estimated by detecting the pressure difference before and after the exhaust gas purification means that changes when the intake throttle valve is opened / closed, and it can be determined whether or not the intake throttle valve is abnormal. It will be possible. Incidentally, the exhaust purification means is a particulate filter capable of temporarily collecting particulate matter contained in the exhaust, NOx stored when the air-fuel ratio of the exhaust is lean, and NOx stored in the presence of a reducing agent. NOx catalyst to reduce,
Other catalysts having an oxidizing function can be exemplified.

In the present invention, the abnormality determining means is
When the value detected by the differential pressure sensor is larger than the range of the pressure difference calculated by the allowable value calculation means, the opening degree of the intake throttle valve is larger than the opening degree requested by the intake throttle valve control means. Is larger, while the value detected by the differential pressure sensor is smaller than the range of the pressure difference calculated by the allowable value calculating means, the opening of the intake throttle valve is determined by the intake throttle valve control means. It can be determined that the opening is smaller than the requested opening.

If there is an abnormality that the intake throttle valve does not open to the required opening, the intake amount decreases with respect to the required value. As a result, the amount of exhaust gas on the upstream side of the exhaust gas purification unit decreases, so that the pressure difference detected by the differential pressure sensor becomes smaller than the pressure difference range calculated by the allowable value calculation unit. Therefore, when the pressure difference detected by the differential pressure sensor is smaller than the pressure difference range calculated by the allowable value calculating means, the abnormality determining means determines that there is an abnormality that the intake throttle valve does not open to the required opening degree. It becomes possible to judge.
On the other hand, when an abnormality occurs in which the intake throttle valve does not close to the required opening, the intake amount increases with respect to the required value.
As a result, the amount of exhaust gas upstream of the exhaust gas purification means increases, so that the pressure difference detected by the differential pressure sensor becomes larger than the pressure difference range calculated by the allowable value calculation means. Therefore,
When the pressure difference detected by the differential pressure sensor is larger than the pressure difference range calculated by the allowable value calculation means, the abnormality determination means determines that an abnormality has occurred in which the intake throttle valve does not close to the required opening degree. It becomes possible.

In the fifth to eighth aspects of the invention, the exhaust gas purification means includes a NOx catalyst which stores NOx when the air-fuel ratio of the exhaust gas is lean and which reduces the stored NOx in the presence of a reducing agent. A filter capable of temporarily collecting particulate matter contained in exhaust gas, wherein the internal combustion engine further comprises a reducing agent supply means for supplying a reducing agent to the filter,
The abnormality determination means can perform the abnormality determination when the reducing agent is being supplied from the reducing agent supply means to the filter.

In the internal combustion engine thus constructed, when the reducing agent is supplied, the EGR gas amount is reduced, for example, in the gasoline engine, while the EGR gas amount is increased in the diesel engine. Since the flow rate of the filter changes, the exhaust pressure upstream of the filter or the pressure difference before and after the filter changes. Therefore, it is possible to determine the abnormality of the EGR valve and the intake throttle valve by comparing the pressure or the differential pressure detected at this time with the pressure at the normal time.

In the fifth to eighth inventions, the exhaust gas purification means is a filter capable of temporarily collecting the particulate matter contained in the exhaust gas, and the collection amount of the particulate matter collected by the filter. Further comprises a collection amount detection means for detecting, and the abnormality determination means, the larger the amount of particulate matter detected by the collection amount detection means, the larger the calculated value of the allowable value calculation means The abnormality can be determined by correcting the error.

In the internal combustion engine thus constructed, the particulate matter in the exhaust gas is collected by the filter. Depending on the operating condition of the engine, the trapped particulate matter accumulates without being removed, and the flow resistance when the exhaust gas passes through the filter increases. As a result, the pressure of the exhaust gas upstream of the filter increases, or the pressure difference between the filter upstream and downstream increases,
If the opening / closing abnormality determination of the EGR valve and the intake throttle valve is performed in this state, an erroneous determination may occur. Therefore, it is possible to make a highly accurate abnormality determination by performing a correction such that the estimated value of the allowable value calculating means is increased according to the amount of particulate matter deposited.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> Specific embodiments of an internal combustion engine abnormality determination method and apparatus according to the present invention will be described below with reference to the drawings. Here, the case where the method and apparatus for determining an abnormality of an internal combustion engine according to the present invention are applied to a diesel engine for driving a vehicle that operates at a lean air-fuel ratio will be described as an example.

FIG. 1 is a diagram showing a schematic configuration of an engine to which the internal combustion engine according to the present embodiment is applied and its intake and exhaust system. In the present embodiment, an in-cylinder direct injection diesel engine equipped with four cylinders 2 is adopted.

An intake branch pipe 3 is connected to the engine 1, and each branch pipe of the intake branch pipe 3 communicates with a combustion chamber of each cylinder 2 through an intake port (not shown).

The intake branch pipe 3 is connected to one end of an intake pipe 4, and the other end of the intake pipe 4 is connected to an air cleaner box 5.

An intake throttle valve 7 for adjusting the flow rate of intake air flowing through the intake pipe 4 is provided at a portion of the intake pipe 4 located immediately upstream of the intake branch pipe 3. The intake throttle valve 7 is provided with an intake throttle actuator 8 configured by a step motor or the like to open and close the intake throttle valve 7. Further, the intake throttle valve 7 is provided with an intake throttle valve opening sensor 9 which outputs an electric signal according to the opening thereof.

In the intake system configured as described above, the intake air flowing into the air cleaner box 5 is cleaned by the filter (not shown) in the air cleaner box 5 to remove dust and the like from the intake air, and then the intake pipe 4 Through the intake branch pipe 3. The intake air that has flowed into the intake branch pipe 3 is distributed to the combustion chamber of each cylinder 2 through each branch pipe, and is burned using the fuel injected from the fuel injection valve (not shown) of each cylinder 2 as an ignition source. .

On the other hand, an exhaust branch pipe 10 is connected to the engine 1, and each branch pipe of the exhaust branch pipe 10 communicates with a combustion chamber of each cylinder 2 through an exhaust port (not shown).

The exhaust branch pipe 10 is connected to one end of an exhaust pipe 11, and the other end of the exhaust pipe 11 is connected downstream to a muffler (not shown).

In the middle of the exhaust pipe 11, a storage reduction type N
A particulate filter carrying an Ox catalyst (hereinafter,
Simply called a filter. ) 12 are provided. A pressure sensor 13 that outputs an electric signal corresponding to the pressure of the exhaust gas flowing through the exhaust pipe 11 is attached to the exhaust pipe 11 upstream of the filter 12.

In the exhaust system configured as described above, the air-fuel mixture (burnt gas) burned in each cylinder 2 of the engine 1 is discharged to the exhaust branch pipe 10 through the exhaust port and is exhausted through the exhaust pipe 11. The particulate matter (hereinafter, simply referred to as PM) in the exhaust gas flowing into the filter 12 is collected and harmful gas components are removed or purified. P with filter 12
The exhaust gas from which M has been collected and harmful gas components have been removed or purified is discharged into the atmosphere through the muffler.

The exhaust branch pipe 10 and the intake branch pipe 3 recirculate a part of the exhaust gas flowing in the exhaust branch pipe 10 to the intake branch pipe 3 (hereinafter referred to as EGR passage) 14.
Are communicated via. A flow rate adjusting valve configured of an electromagnetic valve or the like in the middle of the EGR passage 14 and changing the flow rate of exhaust gas (hereinafter, referred to as EGR gas) flowing in the EGR passage 14 according to the magnitude of applied power. (Hereafter, EG
Use R valve. ) 15 are provided.

In the EGR mechanism constructed as described above, E
When the GR valve 15 is opened, the EGR passage 14 is brought into conduction, and a part of the exhaust gas flowing through the exhaust branch pipe 10 is removed from the E
It flows into the GR passage 14 and is guided to the intake branch pipe 3. The EGR gas recirculated to the intake branch pipe 3 is introduced into the combustion chamber of each cylinder 2 while being mixed with the fresh air flowing from the upstream side of the intake branch pipe 3.

Here, the EGR gas contains an inert gas component such as water (H ₂ O) and carbon dioxide (CO ₂ ) which does not burn by itself and has a high heat capacity. Therefore, when EGR gas is contained in the air-fuel mixture, the combustion temperature of the air-fuel mixture is lowered, and thus nitrogen oxide (NOx)
Is suppressed.

Next, the filter 12 according to this embodiment will be described.

FIG. 2 is a sectional view of the filter 12. FIG. 2A is a diagram showing a cross section of the filter 12 in the lateral direction. FIG. 2B is a diagram showing a vertical cross section of the filter 12.

As shown in FIGS. 2A and 2B, the filter 12 is of a so-called wall flow type having a plurality of exhaust flow passages 50 and 51 extending in parallel with each other. These exhaust flow passages are composed of an exhaust inflow passage 50 whose downstream end is closed by a plug 52 and an exhaust outflow passage 51 whose upstream end is closed by a plug 53. The hatched portion in FIG. 2A indicates the plug 53. Therefore, the exhaust inflow passages 50 and the exhaust outflow passages 51 are alternately arranged via the thin partition walls 54. In other words, in the exhaust inflow passage 50 and the exhaust outflow passage 51, each exhaust inflow passage 50 is surrounded by four exhaust outflow passages 51, and each exhaust outflow passage 51 includes four exhaust inflow passages 50.
It is arranged to be surrounded by.

The filter 12 is made of a porous material such as cordierite. Therefore, the exhaust gas that has flowed into the exhaust gas inflow passage 50 flows through the surrounding partition wall 54 as indicated by the arrow in FIG. 2B. It flows out into the adjacent exhaust outflow passage 51.

In the present embodiment, a carrier layer made of alumina, for example, is provided on the peripheral wall surfaces of each exhaust inflow passage 50 and each exhaust outflow passage 51, that is, on both side surfaces of each partition wall 54 and on the inner wall surfaces of the pores in each partition wall 54. It is formed, and the NOx storage reduction catalyst is carried on this carrier.

Next, the function of the NOx storage reduction catalyst carried by the filter 12 according to the present embodiment will be described.

The filter 12 uses, for example, alumina as a carrier, and potassium (K) and sodium (N
a), an alkali metal such as lithium (Li) or cesium (Cs), an alkaline earth such as barium (Ba) or calcium (Ca), and a rare earth such as lanthanum (La) or yttrium (Y). And at least one of them is carried and a noble metal such as platinum (Pt). In the present embodiment, barium (Ba) and platinum (Pt) are supported on a carrier made of alumina, and ceria (Ce ₂ O ₃ ) having an O ₂ storage capacity is further supported.
An NOx storage reduction catalyst was added.

The NOx catalyst thus constructed is
When the exhaust gas flowing into the Ox catalyst has a high oxygen concentration, nitrogen oxides (NOx) in the exhaust gas are stored.

On the other hand, the NOx catalyst releases the nitrogen oxides (NOx) stored when the oxygen concentration of the exhaust gas flowing into the NOx catalyst decreases. At that time, if a reducing component such as hydrocarbon (HC) or carbon monoxide (CO) is present in the exhaust gas, the NOx catalyst converts the nitrogen oxide (NOx) released from the NOx catalyst into nitrogen (N). It can be reduced to ₂ ).

By the way, when the engine 1 is in the lean burn operation, the air-fuel ratio of the exhaust gas discharged from the engine 1 becomes a lean atmosphere and the oxygen concentration of the exhaust gas becomes high.
Nitrogen oxides (NOx) contained in the exhaust gas will be stored in the NOx catalyst, but if the lean burn operation of the engine 1 is continued for a long period of time, the NOx storage capacity of the NOx catalyst will be saturated, and Nitrogen oxides (NOx) are released into the atmosphere without being removed by the NOx catalyst.

Particularly, in a diesel engine such as the engine 1, a lean air-fuel ratio mixture is burned in most operating regions, and accordingly, the exhaust air-fuel ratio becomes lean air-fuel ratio in most operating regions. , N of NOx catalyst
Ox storage capacity is easily saturated. Incidentally, the lean air-fuel ratio here is, for example, 20 to 50 in a diesel engine,
It means a region where the three-way catalyst cannot purify NOx.

Therefore, when the engine 1 is in the lean burn operation, the concentration of oxygen in the exhaust flowing into the NOx catalyst is reduced and the concentration of the reducing agent is increased before the NOx storage capacity of the NOx catalyst is saturated, and the NOx concentration is increased. It is necessary to reduce the nitrogen oxides (NOx) stored in the catalyst.

As a method of lowering the oxygen concentration in this way, after the fuel is added to the exhaust gas or the amount of EGR gas to be recirculated is increased to increase the soot generation amount to the maximum,
Low temperature combustion that further increases the EGR gas amount (Patent No. 311
No. 6876), a method such as fuel injection during the expansion stroke into the cylinder 2 can be considered. In the present embodiment, the oxygen concentration of the exhaust gas flowing into the filter 12 is reduced by the low temperature combustion and the concentration of the reducing agent is increased.

The engine 1 configured as described above is provided with an electronic control unit (ECU) 6 for controlling the engine 1. The ECU 6 is a unit that controls the operating state of the engine 1 in accordance with the operating conditions of the engine 1 and the driver's request.

The ECU 6 includes an intake throttle valve opening sensor 9,
Various sensors such as the pressure sensor 13 are connected via electrical wiring, and the output signals of the various sensors described above are input to the ECU 6.

On the other hand, the intake throttle actuator 8, the EGR valve 15 and the like are connected to the ECU 6 via electrical wiring, and the ECU 6 can control the above-mentioned respective parts.

The ECU 6 has application programs such as a fuel injection control routine for controlling the fuel injection valve, an intake throttle control routine for controlling the intake throttle valve 7, an EGR control routine for controlling the EGR valve 15, and the like. I remember. Further, the ECU 6 stores various control maps in addition to the above application programs.

Next, a method for detecting an abnormality in the EGR valve 15 according to this embodiment will be described.

Here, if the EGR valve 15 is controlled to the open side, the EGR gas amount increases, so the filter 1 is correspondingly increased.
The amount of exhaust flowing into 2 is reduced. Therefore, the exhaust pressure upstream of the filter 12 (pre-filter pressure) detected by the pressure sensor 13 becomes small. On the other hand, when the EGR valve 15 is controlled to the closing side, the amount of EGR gas decreases, and the amount of exhaust gas flowing into the filter 12 increases accordingly. Therefore, the pressure of the exhaust gas upstream of the filter 12 detected by the pressure sensor 13 increases. As described above, since the opening degree of the EGR valve 15 and the pressure before the filter 12 have a correlation, it is possible to obtain the opening degree of the EGR valve 15 by detecting the pressure before the filter 12.

FIG. 3 is a diagram showing the relationship between the engine load when opening and closing the EGR valve, the pre-filter pressure and the intake air amount, and the abnormality determination value when the EGR valve is required to be fully opened. The solid line in FIG. 3 shows the value when the EGR valve 15 is normally fully opened or fully closed, while the broken line shows the determination value when the EGR valve 15 is not fully opened.

Here, when the engine load increases, the intake air amount increases accordingly, and the pressure before the filter 12 rises. The ECU 6 causes the EGR valve 1 to fully open the EGR valve 15.
If the EGR valve 15 does not fully open even though the signal is transmitted to 5, the amount of EGR that actually recirculates becomes smaller than the required amount, and the pressure before the filter 12 becomes high.

Therefore, in the present embodiment, the engine operating conditions and the pressure before the filter 12 when the EGR valve 15 is fully opened are previously obtained by an experiment or the like, and a value larger than this value by a predetermined amount or more is used as the determination value. Here, the reason why the value is larger than the predetermined amount is to consider the variation due to the individual difference of each member. The judgment value thus obtained is shown by the broken line in FIG. Then, the engine load and the filter 12
When the value obtained by substituting the front pressure into FIG. 3 is larger than the value indicated by the broken line in FIG. 3, it is determined that the EGR valve 15 has not been opened until it is fully opened. .

Next, FIG. 4 is a diagram showing the relationship between the engine load when opening and closing the EGR valve, the pre-filter pressure and the intake air amount, and the abnormality determination value when the EGR valve is required to be fully closed.
The solid line in FIG. 4 shows the value when the EGR valve 15 is normally fully opened or fully closed, while the broken line shows the determination value when the EGR valve 15 is not closed until fully closed.

Here, when the engine load increases, the intake air amount increases accordingly, and the pressure before the filter 12 rises. The ECU 6 causes the EGR valve 1 to fully close the EGR valve 15.
If the EGR valve 15 is not fully closed even though the signal is transmitted to 5, the amount of EGR that actually recirculates becomes larger than the required amount, and the pressure before the filter 12 becomes low.

Therefore, in the present embodiment, the engine operating conditions and the pressure before the filter 12 when the EGR valve 15 is fully closed are obtained in advance by experiments or the like, and a value smaller than this value by a predetermined amount or more is used as the determination value. . Here, the reason why the value is smaller than the predetermined amount is to consider the variation due to the individual difference of each member. The judgment value thus obtained is shown by the broken line in FIG. When the value obtained by substituting the engine load and the pre-filter pressure in FIG. 4 is smaller than the value indicated by the broken line in FIG. 4, the EGR valve 15 has not been closed until it is fully closed. It is determined that they are doing.

Even when the required opening degree of the EGR valve 15 is other than when the EGR valve 15 is fully open or fully closed, the opening / closing abnormality of the EGR valve 15 can be determined in the same manner by previously determining the determination value. .

As described above, when the pressure detected by the pressure sensor 13 is larger than the required pressure obtained by the experiment or the like by the predetermined value or more, the EGR valve 15 does not open to the required opening, and the abnormality on the open side does not occur. On the other hand, when it is smaller than the required pressure obtained by experiments or the like by a predetermined value or more, it can be determined that the EGR valve 15 is not closed to the required opening degree and the closing side is abnormal.

Here, in the conventional internal combustion engine abnormality determining method and device, the output signal of the air flow meter is required to determine the opening / closing abnormality of the EGR valve. Therefore, it was necessary to provide an air flow meter. Further, since the EGR valve needs to be forcibly opened and closed, there is a possibility that the operating state may be affected.

In this regard, in the internal combustion engine abnormality determination method and apparatus according to the present embodiment, in order to detect the amount of PM accumulated in the filter, the exhaust gas upstream of the filter, which is often employed in internal combustion engines equipped with the filter, is used. The opening / closing abnormality of the EGR valve can be determined by using the output signal of the pressure sensor that detects the pressure. Therefore, an air flow meter is not required and the operating condition of the engine is not deteriorated.

As described above, according to the present embodiment, it is possible to judge the opening / closing abnormality of the EGR valve based on the pressure before the filter. <Second Embodiment> This embodiment is different from the first embodiment in the following points.

In this embodiment, in order to reduce the NOx stored in the NOx storage reduction catalyst, the EGR is performed during the rich spike control in which the air-fuel ratio of the exhaust gas is reduced to the stoichiometric air-fuel ratio or less in a spike manner (temporarily). Determine whether the valve is open or closed.

Here, the case where the method and apparatus for determining an abnormality of an internal combustion engine according to the present invention are applied to an in-cylinder direct injection gasoline engine for driving a vehicle operated with a lean air-fuel ratio will be described as an example.

In the gasoline engine according to this embodiment, the rich spike control is performed by increasing the fuel injection amount. Further, in the gasoline engine according to the present embodiment, the amount of fresh air drawn into the engine 1 is reduced during the rich spike. In this way, the increase in fuel consumption is suppressed and the torque fluctuation due to the fuel increase is suppressed. On the other hand, when the engine is operated at a lean air-fuel ratio, it is difficult to purify NOx, so the EGR gas is recirculated to suppress the generation of NOx. However, if the EGR gas is recirculated at the time of the rich spike, the combustion state in the cylinder may be deteriorated, and the emission may be deteriorated or the torque may be changed. Therefore, in the present embodiment, the EGR gas is reduced or the recirculation is stopped during the rich spike.

Although the basic structure of other hardware is different from that of the gasoline engine and the diesel engine, the description is omitted because it is common to the first embodiment.

FIG. 5 shows the required air-fuel ratio of the exhaust gas during the rich spike, the intake throttle valve opening, the EGR valve required opening, and the actual EG.
It is a figure showing the relation of R valve opening and pre-filter pressure. The broken line in FIG. 5 indicates the required value.

Here, when the rich spike control is started during the normal operation at the lean air-fuel ratio, the intake throttle valve 7 is controlled to the closing side and the intake fresh air amount is reduced. As a result, the pressure of exhaust gas before the filter 12 is reduced.

At the same time, the EGR valve 15 is controlled to the closing side to reduce the recirculation amount of EGR gas. Where EG
When the R valve 15 is controlled to the closing side, the amount of exhaust flowing into the filter 12 increases and the exhaust pressure upstream of the filter 12 increases. However, if the EGR valve 15 is not closed to the required opening degree, more EGR gas than the required amount will be recirculated. Therefore, the amount of exhaust flowing into the filter 12 is reduced. As a result, the pressure before the filter 12 becomes lower and the deviation from the pressure before the filter 12 during normal operation becomes larger than when the EGR valve 15 is closed to the required opening.

Therefore, in this embodiment, the opening / closing abnormality of the EGR valve 15 is determined by the amount of change in the pressure before the filter 12 when the rich spike control is started from the state where the normal operation is performed. That is, when the deviation between the pressure before the filter 12 during the normal operation and the pressure before the filter 12 when the rich spike control is started is equal to or more than a predetermined value, the EG
It is determined that an abnormality has occurred in which the R valve 15 does not close to the required opening.

Here, the predetermined value used for the determination is EG
In the case where the R valve 15 is normal, the deviation of the pressure before the filter 12 before and after the rich spike is obtained by an experiment or the like in advance for each engine speed and engine load, and the variation due to individual difference of each member is added to this It has a value. This value is made into a map and stored in the ECU 6, and the ECU 6 calculates the determination value based on the engine speed and the engine load immediately before the start of the rich spike control. The engine speed can be obtained by a crank position sensor (not shown) that detects the rotation speed of the crankshaft, and the engine load can be obtained by an accelerator opening sensor (not shown) that detects the depression amount of the accelerator opening. .

In this embodiment, instead of the change amount of the pressure before the filter 12, only the pressure value before the filter 12 during the rich spike control is used to determine the opening / closing abnormality of the EGR valve 15. good. In this case, a determination value is set in advance for each engine speed and engine load from the pressure value before the filter 12 obtained by experiments or the like, and when the pressure lower than this determination value is detected, the EGR valve 15 is required to open. It is possible to determine that there is an abnormality that does not close the valve.

As described above, according to the present embodiment, the filter 12 before and after the rich spike control is started.
The opening / closing abnormality of the EGR valve can be determined based on the previous pressure.

In the present embodiment, the case where the present invention is applied to the direct injection gasoline engine of the cylinder is described as an example, but instead of this, the present invention may be applied to the lean burn gasoline engine of the port injection. it can.

Further, instead of the filter carrying the NOx storage reduction catalyst, a filter having an oxidizing function may be used. <Third Embodiment> This embodiment is different from the first embodiment in the following points.

In the present embodiment, in order to reduce the NOx stored in the NOx storage reduction catalyst, the EGR is performed during the rich spike control in which the air-fuel ratio of the exhaust gas is reduced (temporarily) to the stoichiometric air-fuel ratio or less. Determine whether the valve is open or closed.

Here, the case where the method and apparatus for determining an abnormality of an internal combustion engine according to the present invention are applied to a diesel engine for driving a vehicle which operates at a lean air-fuel ratio will be described as an example.

In the diesel engine according to the present embodiment, the amount of fresh air drawn into the engine 1 is reduced during the rich spike. In this way, an increase in the consumption of fuel that is a reducing agent is suppressed. On the other hand, in the present embodiment, low temperature combustion (Patent No. 3116876) is performed to further increase the EGR gas amount after increasing the recirculated EGR gas amount and increasing the soot generation amount to the maximum. . By thus increasing the EGR gas amount, it becomes possible to easily achieve the rich air-fuel ratio.

The basic structure of other hardware is the same as that of the first embodiment, and therefore its explanation is omitted.

FIG. 6 shows the required air-fuel ratio of the exhaust gas during the rich spike, the intake throttle valve opening, the EGR valve required opening, and the actual EG.
It is a figure showing the relation of R valve opening and pre-filter pressure. The broken line in FIG. 6 indicates the required value.

Here, when the rich spike control is started during the normal operation at the lean air-fuel ratio, the intake throttle valve 7 is controlled to the closing side and the intake fresh air amount is reduced. As a result, the pressure of exhaust gas before the filter 12 is reduced.

At the same time, the EGR valve 15 is controlled to the open side, and the recirculation amount of EGR gas is increased. Where EG
When the R valve 15 is controlled to the open side, the amount of exhaust gas flowing into the filter 12 decreases and the exhaust gas pressure upstream of the filter 12 decreases. However, when the EGR valve 15 does not open to the required opening degree, less EGR gas than the required amount is recirculated. Therefore, the amount of exhaust gas flowing into the filter 12 increases. As a result, the pressure before the filter 12 becomes higher and the deviation from the pressure before the filter 12 during normal operation becomes smaller than when the EGR valve 15 is opened to the required opening.

Therefore, in this embodiment, the opening / closing abnormality of the EGR valve 15 is determined by the change amount of the pressure before the filter 12 when the rich spike control is started from the state where the normal operation is performed. That is, when the deviation between the pressure before the filter 12 during normal operation and the pressure before the filter 12 when the rich spike control is started is less than or equal to a predetermined value, EG
It is determined that an abnormality has occurred in which the R valve 15 does not open to the required opening degree.

Here, the predetermined value used for the determination is EG
In the case where the R valve 15 is normal, the deviation of the pressure before the filter 12 before and after the rich spike is obtained by an experiment or the like in advance for each engine speed and engine load, and the variation due to the individual difference of each member is added to this. It has a value. This value is made into a map and stored in the ECU 6, and the ECU 6 calculates the determination value based on the engine speed and the engine load immediately before the start of the rich spike control. The engine speed can be obtained by a crank position sensor (not shown) that detects the rotation speed of the crankshaft, and the engine load can be obtained by an accelerator opening sensor (not shown) that detects the depression amount of the accelerator opening. .

In the present embodiment, instead of the change amount of the pressure before the filter 12, only the pressure value before the filter 12 during the rich spike control is used to determine the opening / closing abnormality of the EGR valve 15. good. In this case, a judgment value is set in advance for each engine speed and engine load from the pressure value before the filter 12 obtained by an experiment or the like, and when the pressure higher than this judgment value is detected, the EGR valve 15 is required to open. It can be determined that an abnormality has occurred in which the valve does not open frequently.

As described above, according to the present embodiment, the filter 12 before and after the start of rich spike control.
The opening / closing abnormality of the EGR valve can be determined based on the previous pressure.

In this embodiment, the case where the filter is provided has been described, but instead of this, a NOx catalyst may be provided. <Fourth Embodiment> In the present embodiment, it is determined whether the intake throttle valve is open or closed based on the engine load and the pre-filter pressure.

Here, the case where the method and apparatus for determining an abnormality of an internal combustion engine according to the present invention is applied to a diesel engine for driving a vehicle which operates at a lean air-fuel ratio will be described as an example.

The basic structure of other hardware is the same as that of the first embodiment, and the description thereof is omitted.

Next, a method for detecting an abnormality of the intake throttle valve according to this embodiment will be described.

Here, when the intake throttle valve 7 is controlled to the closing side, the amount of fresh intake air decreases, so the filter 12 is correspondingly reduced.
The amount of exhaust gas flowing into is reduced. Therefore, the pressure sensor 1
The pressure before the filter 12 detected at 3 becomes smaller. On the other hand, when the intake throttle valve 7 is controlled to the open side, the amount of fresh intake air increases, and the amount of exhaust gas flowing into the filter 12 increases accordingly. Therefore, the pressure before the filter 12 detected by the pressure sensor 13 becomes large. In this way, since the opening degree of the intake throttle valve 7 and the pressure before the filter 12 have a correlation, the opening degree of the intake throttle valve 7 can be obtained by detecting the pressure before the filter 12. .

FIG. 7 is a diagram showing the relationship between the engine load and the judgment value of the pre-filter pressure when the intake throttle valve does not open to the required opening degree. When the engine load increases, the intake air amount increases accordingly, and the pressure in front of the filter 12 increases. Here, when the intake throttle valve 7 does not open to the required opening degree, that is, when the amount of fresh air actually sucked into the engine is less than the required amount, the flow rate of the exhaust gas decreases, so The pressure becomes low (at the time of abnormality in FIG. 7).

Here, the pressure before the filter 12 when the intake throttle valve 7 is normal according to the required opening is previously obtained by an experiment or the like, and a value smaller than this value by a predetermined amount or more is set as a determination value. Here, the reason why the value is smaller than the predetermined amount is to consider the variation due to the individual difference of each member.
When the pressure before the filter 12 detected by the pressure sensor 13 is smaller than the determination value determined from the engine load,
It can be determined that the intake throttle valve 7 does not open to the required opening degree or more.

As described above, when the pressure detected by the pressure sensor 13 is smaller than the required pressure obtained by the experiment or the like by the predetermined value or more, the intake throttle valve 7 on the open side is not opened to the required opening degree. It can be determined to be abnormal.

In this embodiment, the filter 12 has P
When M is deposited, the determination value can be set high according to the amount of PM deposited.

FIG. 8 is a diagram showing the relationship between the engine load and the pressure before the filter when PM is deposited on the filter.
When a large amount of PM is deposited on the filter 12, the resistance of the exhaust gas passing through the filter 12 increases, and the pressure before the filter 12 increases. At this time, if the open / close abnormality of the intake throttle valve 7 is determined using the determination value when PM is not accumulated, it may be determined to be normal despite the occurrence of abnormality. .

Therefore, in the present embodiment, first, the amount of PM deposited on the filter 12 is detected, and the determination value is corrected based on this value. The accumulated amount of PM is detected by, for example, attaching a differential pressure sensor (not shown) that detects the differential pressure before and after the filter 12, and obtaining the PM amount corresponding to the differential pressure sensor in advance by experiments or the like. You can In addition, operating conditions that may cause soot (for example, during low temperature combustion)
The PM deposition amount may be estimated according to the vehicle travel distance or time.

The increment of the pre-filter 12 pressure corresponding to the PM deposition amount thus obtained is added to the determination value. The increment of the pressure before the filter 12 to be added at this time can be obtained in advance by experiments or the like based on the amount of PM deposited.

In this way, even if PM is deposited on the filter 12, it is possible to determine whether the intake throttle valve 7 is open or closed based on the pressure before the filter 12.

Further, in the present embodiment, when the pre-filter 12 pressure increases or decreases by a predetermined value or more in a short time (for example, within 1 second), it can be determined that an abnormality has occurred in the intake throttle valve 7. it can.

FIG. 9 is a diagram showing the relationship between the engine load and the abnormality determination value when the pre-filter pressure rises in a short time. Such a sudden change in pre-filter pressure causes PM
It does not occur due to the accumulation of For example, if contact failure or the like occurs in a connector for supplying power for operating the intake throttle valve actuator 8 due to vibration during traveling,
The pressure before the filter 12 may change in a short time. In the present embodiment, the amount of pressure change when an abnormality occurs in the intake throttle valve 7 is obtained by experiments or the like for each engine load, and is stored in the ECU 6 as a determination value. Then, for example, if the pressure change amount for one second is equal to or greater than the determination value, it can be determined that the intake throttle valve 7 has the above.

As described above, according to the present embodiment, it is possible to determine whether the intake throttle valve is open / closed abnormally based on the pre-filter pressure. <Fifth Embodiment> In the present embodiment, the opening / closing abnormality of the intake throttle valve is determined based on the pre-filter pressure.

Here, a case where the method and apparatus for determining an abnormality of an internal combustion engine according to the present invention is applied to a diesel engine for driving a vehicle which operates at a lean air-fuel ratio will be described as an example.

The basic structure of other hardware is the same as that of the first embodiment, and therefore its explanation is omitted.

Next, a method for detecting an abnormality of the intake throttle valve according to this embodiment will be described.

When the driver of the vehicle depresses an accelerator pedal (not shown), the accelerator opening sensor (not shown) which transmits a signal corresponding to the accelerator opening detects the accelerator opening. Then, the ECU 6 controls the intake throttle valve actuator 8 based on the output signal of the accelerator opening sensor. Here, the intake throttle valve 7 is provided with an intake throttle valve opening sensor 9 that outputs a signal according to the opening thereof, and the opening degree of the intake throttle valve 7 is monitored by the ECU 6. In the present embodiment, an abnormality occurs in the intake throttle valve opening sensor 9 and the intake throttle actuator 8, which causes the intake throttle valve 7 to open excessively with respect to the driver's accelerator depression amount. The determination is made regardless of the degree sensor 9.

FIG. 10 is a diagram showing the pre-filter pressure, the intake throttle valve actual opening, and the intake throttle valve required opening when the intake throttle valve opening is normal and when an abnormality occurs.
The intake throttle valve required opening degree is the amount by which the driver actually depresses the accelerator pedal.

Here, if the intake throttle valve 7 opens too much with respect to the required opening degree, the amount of fresh intake air increases, and the amount of exhaust gas flowing into the filter 12 increases accordingly. Therefore, the pressure before the filter 12 detected by the pressure sensor 13 increases. Thus, the actual opening of the intake throttle valve 7 and the filter 12
Since there is a correlation with the previous pressure, the actual opening of the intake throttle valve 7 can be obtained by detecting the pressure before the filter 12, and the intake throttle valve 7 is controlled to reach the required opening. It can be determined whether or not it has been done.

In the present embodiment, the pressure before the filter 12 with respect to the required opening degree of the intake throttle valve 7 is previously obtained by an experiment or the like and mapped using the engine speed and the engine load as parameters. Then, when the detected pre-filter 12 pressure is higher than the pre-filter 12 pressure with respect to the required opening by a predetermined ratio or more, it can be determined that the intake throttle valve 7 is too open above the required opening. Similarly, if the detected pre-filter 12 pressure is smaller than the pre-filter 12 pressure with respect to the required opening by a predetermined ratio or more, it can be determined that the intake throttle valve 7 has not been opened to the required opening.

In this embodiment, when the response speed of the intake throttle valve 7 decreases with respect to the required opening degree of the intake throttle valve 7, an abnormality occurs in which the responsiveness of the intake throttle valve 7 deteriorates. It can be determined that

FIG. 11 is a diagram showing an example of the pressure before the filter 12, the intake throttle valve actual opening, and the intake throttle valve required opening when the response of the intake throttle valve deteriorates when the intake throttle valve is closed. is there. In the case of this example, the intake throttle valve can be opened at the normal speed, but the valve closing speed is slower than that at the normal time.

In such a case, the ECU 6 obtains the required valve closing speed obtained from the required opening degree of the intake throttle valve 7, while obtaining the actual valve closing speed obtained from the temporal change of the pressure before the filter 12. When the actual valve closing speed is smaller than the required valve closing speed by a predetermined value or more, it can be determined that an abnormality that the response is poor occurs when the intake throttle valve 7 is closed. In addition, when the time before the pressure before the filter 12 detected when the intake throttle valve 7 is closed to the pressure according to the required opening degree that is previously obtained by experiments or the like is a predetermined time or more, the intake throttle valve 7 It may be determined that an abnormality that deteriorates the responsiveness has occurred.

Next, FIG. 12 shows an example of the pressure before the filter 12, the actual intake throttle valve opening, and the required intake throttle valve opening when the response of the intake throttle valve deteriorates when the intake throttle valve is opened. It is a figure.

Similar to the above-described valve closing, the required valve opening speed obtained from the required opening degree of the intake throttle valve 7 is obtained, while the actual valve opening speed obtained from the temporal change of the pressure before the filter 12 is obtained, When the actual valve opening speed is smaller than the required valve opening speed by a predetermined value or more, it can be determined that an abnormality that the response is poor occurs when the intake throttle valve 7 is opened. Further, if it takes a predetermined time or more after the driver depresses the accelerator pedal to increase the pressure before the filter 12 to the predetermined pressure, the responsiveness until the intake throttle valve 7 is opened deteriorates. You may decide that there is. Here, the predetermined pressure is the pressure before the filter 12 that corresponds to the accelerator depression amount, and is determined in advance by experiments or the like. Therefore, according to the present embodiment, the intake throttle is determined based on the pressure upstream of the filter 12. Deterioration of valve responsiveness can be determined. <Sixth Embodiment> In the present embodiment, the storage reduction type N
In order to reduce the NOx stored in the Ox catalyst, during the rich spike control in which the air-fuel ratio of the exhaust gas is reduced to the stoichiometric air-fuel ratio or less in a spike manner (temporary), the opening / closing abnormality of the intake throttle valve is determined.

Here, the case where the method and apparatus for determining an abnormality of an internal combustion engine according to the present invention are applied to an in-cylinder direct injection gasoline engine for driving a vehicle which is operated at a lean air-fuel ratio will be described as an example.

The basic structure of other hardware is the same as that of the second embodiment, and therefore its explanation is omitted.

FIG. 13 is a diagram showing the relationship among the required air-fuel ratio of the exhaust gas, the intake throttle valve opening, and the pre-filter pressure at the time of rich spike. The broken line shows the required value, and the solid line shows the actual value.

Here, when the rich spike control is started during the normal operation at the lean air-fuel ratio, the intake throttle valve 7 is controlled to the closing side and the intake fresh air amount is reduced. As a result, the pressure of exhaust gas before the filter 12 is reduced.

However, if the intake throttle valve 7 is not closed to the required opening degree, more fresh air than the required amount will be sucked into the engine. Therefore, the amount of exhaust gas flowing into the filter 12 increases. As a result, the pressure before the filter 12 becomes higher and the deviation from the pressure before the filter 12 during normal operation becomes smaller than when the intake throttle valve 7 is closed to the required opening.

Therefore, in the present embodiment, the opening / closing abnormality of the intake throttle valve 7 is determined by the change amount of the pressure before the filter 12 when the rich spike control is started from the state where the normal operation is performed. That is, when the deviation between the pressure before the filter 12 during normal operation and the pressure before the filter 12 when the rich spike control is started is less than or equal to a predetermined value, an abnormality occurs in which the intake throttle valve 7 does not close to the required opening degree. It is determined that

Here, the predetermined value used for the determination is obtained when the intake throttle valve 7 is normal and the deviation of the pressure before the filter 12 before and after the rich spike is obtained by an experiment or the like in advance for each engine speed and engine load. This is a value obtained by adding the variation amount due to the individual difference of each member. This value is made into a map and stored in the ECU 6, and the ECU 6 calculates the determination value based on the engine speed and the engine load immediately before the start of the rich spike control. The engine speed can be obtained by a crank position sensor (not shown) that detects the rotation speed of the crankshaft, and the engine load can be obtained by an accelerator opening sensor (not shown) that detects the depression amount of the accelerator opening. .

In the present embodiment, the open / close abnormality of the intake throttle valve 7 is determined using only the pressure value before the filter 12 during the rich spike control, instead of the change amount of the pressure before the filter 12. Is also good. In this case, a determination value is set in advance for each engine speed and engine load from the pressure value before the filter 12 obtained by experiments or the like, and the intake throttle valve 7 is requested when a pressure higher than this determination value is detected. It can be determined that an abnormality has occurred in which the valve does not close to the opening.

In the present embodiment, the response of the intake throttle valve 7 is abnormal when the response speed of the intake throttle valve 7 decreases with respect to the required opening degree of the intake throttle valve 7 during the rich spike. Can be determined.

FIG. 14 shows an example of the pre-filter pressure, the intake throttle valve actual opening, and the intake throttle valve required opening degree when the response of the intake throttle valve is deteriorated when the intake throttle valve is closed during the rich spike. It is a figure. The broken line shows the required value, and the solid line shows the actual value.

In the case of this example, a response delay occurs when the intake throttle valve 7 is opened and closed, and the opening and closing speed is slower than in the normal state.

In such a case, the ECU 6 obtains the required valve closing speed obtained from the required opening degree of the intake throttle valve 7, while obtaining the actual valve closing speed obtained from the temporal change of the pressure before the filter 12, When the actual valve closing speed is smaller than the required valve closing speed by a predetermined value or more, it can be determined that the responsiveness is deteriorated when the intake throttle valve 7 is opened and closed. Further, the pressure before the filter 12 which is obtained from the required opening degree of the intake throttle valve 7 is previously obtained by an experiment or the like, and the responsiveness of the intake throttle valve 7 is deteriorated when the time to reach this pressure is a predetermined time or more. It can be determined that they are doing.

As described above, according to the present embodiment, it is possible to determine whether the intake throttle valve is open / closed abnormally based on the pre-filter pressure before and after the start of the rich spike control.

In the present embodiment, the case where the present invention is applied to the direct injection gasoline engine of the cylinder is described as an example, but instead of this, the present invention can be applied to a lean burn gasoline engine of the port injection. Further, it can be applied to a diesel engine.

Further, instead of the filter carrying the NOx storage reduction catalyst, a filter having an oxidizing function may be used. <Other Embodiments> In the first to sixth embodiments, a change in the flow rate of exhaust gas is detected as a change in pressure upstream of the filter to determine whether the EGR valve or the intake throttle valve is open / closed abnormally. Here, the opening / closing abnormality of the EGR valve and the intake throttle valve can be determined even if the pressure difference upstream of the filter is replaced with the pressure difference before and after the filter.

That is, when the flow rate of exhaust gas decreases, the pressure upstream of the filter decreases, and at the same time, the pressure difference before and after the filter also decreases. On the other hand, when the flow rate of exhaust increases, the pressure upstream of the filter rises, and at the same time, the pressure difference before and after the filter also increases.

Therefore, when the EGR valve does not open to a predetermined opening or the intake throttle valve does not close to a predetermined opening, and the exhaust flow rate increases,
The pressure difference before and after the filter becomes large, and it becomes possible to determine whether the EGR valve or the intake throttle valve is open / closed abnormally. Similarly, when the EGR valve does not close to a predetermined opening or the intake throttle valve does not open to a predetermined opening and the exhaust flow rate decreases, the pressure before and after the filter is reduced. The difference becomes small, and it becomes possible to determine whether the EGR valve or the intake throttle valve is open / closed abnormally.

A differential pressure sensor for detecting the pressure difference before and after the filter may be provided in order to estimate the amount of PM trapped in the filter in an engine equipped with the filter. Therefore, a new sensor is provided. The cost can be reduced without the need.

[0155]

According to the present invention, it is possible to determine whether or not the opening / closing abnormality has occurred in the intake throttle valve and the EGR valve based on the pressure of the exhaust gas upstream of the filter.

Further, according to the present invention, it is possible to determine whether or not the opening / closing abnormality has occurred in the intake throttle valve and the EGR valve based on the pressure difference between the exhaust gas upstream and downstream of the filter.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an engine to which an internal combustion engine according to an embodiment of the present invention is applied and an intake / exhaust system thereof.

FIG. 2A is a diagram showing a lateral cross section of a particulate filter. (B) is a figure which shows the longitudinal cross section of a particulate filter.

FIG. 3 is a diagram showing a relationship among an engine load, a pre-filter pressure and an intake air amount when the EGR valve is opened and closed, and an abnormality determination value when the EGR valve is required to be fully opened.

FIG. 4 is a diagram showing a relationship among an engine load when opening and closing an EGR valve, a pre-filter pressure, an intake air amount, and an abnormality determination value when the EGR valve is required to be fully closed.

[Fig. 5] A required air-fuel ratio of exhaust gas during a rich spike, an intake throttle valve opening degree, an EGR valve required opening degree, an actual EGR valve opening degree,
It is a figure showing the relation of pre-filter pressure.

FIG. 6 shows a required air-fuel ratio of exhaust gas during a rich spike, an intake throttle valve opening degree, an EGR valve required opening degree, an actual EGR valve opening degree,
It is a figure showing the relation of pre-filter pressure.

FIG. 7 is a diagram showing a relationship between an engine load and a determination value of pre-filter pressure when an intake throttle valve does not open to a required opening.

FIG. 8 is a diagram showing the relationship between the engine load and the pressure before the filter when PM is deposited on the filter.

FIG. 9 is a diagram showing a relationship between an engine load and an abnormality determination value when the pre-filter pressure rises in a short time.

FIG. 10 is a diagram showing the pre-filter pressure, the intake throttle valve actual opening, and the intake throttle valve required opening when the intake throttle valve opening is normal and when an abnormality occurs.

FIG. 11 is a diagram showing an example of the pressure before the filter 12, the intake throttle actual opening, and the intake throttle required opening when the response of the intake throttle is deteriorated when the intake throttle is closed.

FIG. 12 is a diagram showing an example of the pressure before the filter 12, the actual intake throttle valve opening, and the intake throttle required opening when the response of the intake throttle valve deteriorates when the intake throttle valve is opened.

FIG. 13 is a diagram showing a relationship among a required air-fuel ratio of exhaust gas, an intake throttle valve opening degree, and a pre-filter pressure during a rich spike.

FIG. 14 is a view showing an example of pre-filter pressure, intake throttle actual opening, intake throttle required opening when the response of the intake throttle is deteriorated when the intake throttle is closed during rich spike. .

[Explanation of symbols]

1 ... Engine 2 ... Cylinder 3 ... Intake branch pipe 4 ... Intake pipe 5 ... Air cleaner box 6 ... ECU 7 ... Intake throttle valve 8 ... Intake throttle actuator 9 ... Intake throttle valve opening sensor 10 ... Exhaust branch pipe 11 ... Exhaust pipe 12 ... Particulate filter 13 ... Pressure sensor 14 ... EGR passage 15 ... EGR valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/24 F01N 3/24 E 3G301 S 3/28 301 3/28 301N F02D 9/02 341 F02D 9 / 02 341A 21/08 301 21/08 301H 41/22 360 360 41/22 360 F Term (reference) 3G062 AA01 AA03 BA04 BA06 CA06 DA01 DA02 EA10 ED01 ED04 ED10 FA02 FA05 FA06 FA19 GA04 GA06 GA22 3G065 AA01 AA04 CA36 GA06 DA15 DA15 DA15 DA15 GA10 GA41 GA46 HA06 HA21 HA22 JA04 JA09 JA11 KA02 3G090 AA02 EA06 3G091 AA11 AA17 AA18 AA24 AB06 AB13 BA07 BA14 BA21 BA31 CB07 DB10 EA01 EA03 EA07 EA32 FB12 GB03A05 A08 DC05 A08 DC03 A05 AK12 A03 A05 A17 A09 A05 A17 A09 A08 A03 A05 A03 A09 A08 A03 A05 A03 A09 A08 A09 A08 A05 A03 A09 A08 A09 A08 A03 A08 A05 DC03 GA03 HA06Z HD08Z HE01Z HF08Z 3G301 HA02 HA06 HA13 JB02 JB09 KA06 LA03 LB11 NA08 NB03 NC02 PA11Z PD14Z PE01Z PF03Z

Claims (15)

[Claims] 1. In an internal combustion engine for reducing NOx by supplying a reducing agent to a particulate filter carrying a NOx storage reduction catalyst, the EGR valve is opened / closed by a change in pressure upstream of the particulate filter during NOx reduction. An internal combustion engine abnormality determination method for determining an abnormality. 2. In an internal combustion engine that supplies a reducing agent to a particulate filter carrying an NOx storage reduction catalyst to reduce NOx, an EGR is caused by a change in pressure difference between the upstream side and the downstream side of the particulate filter during NOx reduction.
A method for determining abnormality of an internal combustion engine for determining abnormality of valve opening and closing. 3. An internal combustion engine for reducing NOx by supplying a reducing agent to a particulate filter carrying an occlusion reduction type NOx catalyst, wherein the intake throttle valve of the intake throttle valve changes due to a change in pressure upstream of the particulate filter during NOx reduction. An abnormality determination method for an internal combustion engine, which determines an opening / closing abnormality. 4. An internal combustion engine for reducing NOx by supplying a reducing agent to a particulate filter carrying an occlusion-reduction type NOx catalyst, and intake air due to a change in pressure difference between the upstream side and the downstream side of the particulate filter during NOx reduction. A method for determining abnormality of an internal combustion engine for determining abnormality of opening / closing of a throttle valve. 5. An exhaust gas purification means for purifying harmful substances contained in exhaust gas, a pressure detection means for detecting a pressure of exhaust gas upstream of the exhaust gas purification means, and an internal combustion engine for communicating an exhaust system and an intake system of an internal combustion engine. EG that recirculates a part of the exhaust gas discharged from the engine to the intake system of the internal combustion engine
An R passage, an EGR valve that adjusts a flow rate of EGR gas flowing in the EGR passage, an EGR valve control unit that controls opening and closing of the EGR valve according to an operating state of the internal combustion engine, and the EGR valve control unit The pressure estimating means for estimating the pressure of the exhaust gas upstream of the exhaust gas purifying means from the target opening degree of the EGR valve, and that the EGR valve is normal based on the pressure of the exhaust gas estimated by the pressure estimating means. Allowable value calculating means for calculating the range of pressure that can be obtained, and EGR when the value detected by the pressure detecting means is outside the range of pressure calculated by the allowable value calculating means.
An abnormality determination device for an internal combustion engine, comprising: an abnormality determination unit that determines that the valve is abnormally opened and closed. 6. The abnormality determining means, when the value detected by the pressure detecting means is larger than the range of pressure calculated by the allowable value calculating means, the opening degree of the EGR valve is the EGR valve. When the value detected by the pressure detecting means is smaller than the range of pressure calculated by the allowable value calculating means, the opening degree of the EGR valve is smaller than the opening degree requested by the control means. The abnormality determination device for an internal combustion engine according to claim 5, wherein the EGR valve control means determines that the opening degree is larger than the requested opening degree. 7. An exhaust gas purification means for purifying harmful substances contained in exhaust gas, a differential pressure sensor for detecting a pressure difference between exhaust gas upstream and downstream of said exhaust gas purification means, and an exhaust system and an intake system of an internal combustion engine. EG for communicating a part of exhaust gas discharged from the internal combustion engine to the intake system of the internal combustion engine
An R passage, an EGR valve that adjusts a flow rate of EGR gas flowing in the EGR passage, an EGR valve control unit that controls opening and closing of the EGR valve according to an operating state of the internal combustion engine, and an EGR valve control unit A pressure difference estimating means for estimating a pressure difference between exhaust gas upstream and downstream of the exhaust gas purifying means from the target EGR valve opening degree, and an EGR valve based on the exhaust gas pressure difference estimated by the pressure difference estimating means. Allowable value calculating means for calculating a range of pressure difference that can be considered normal, and EGR when the value detected by the differential pressure sensor is outside the range of pressure difference calculated by the allowable value calculating means.
An abnormality determination device for an internal combustion engine, comprising: an abnormality determination unit that determines that the valve is abnormally opened and closed. 8. If the value detected by the differential pressure sensor is larger than the range of the pressure difference calculated by the allowable value calculating means, the abnormality determining means determines that the opening degree of the EGR valve is the EGR valve. If the value detected by the differential pressure sensor is smaller than the pressure difference range calculated by the allowable value calculation means, the opening degree of the EGR valve is smaller than the opening degree requested by the valve control means. The abnormality determination device for an internal combustion engine according to claim 7, wherein is determined to be larger than the opening degree requested by the EGR valve control means. 9. A low temperature combustion in which the amount of soot generated is maximized by increasing the amount of recirculated EGR gas, and a normal combustion before increasing the amount of EGR gas can be switched over. The abnormality determination of the internal combustion engine according to any one of claims 5 to 8, further comprising combustion method selection means, wherein the abnormality determination means makes an abnormality determination when the normal combustion and the low temperature combustion are switched. apparatus. 10. An exhaust gas purifying unit for purifying harmful substances contained in exhaust gas, a pressure detecting unit for detecting a pressure of exhaust gas upstream of the exhaust gas purifying unit, and an amount of fresh air flowing in an intake system of an internal combustion engine. An intake throttle valve to be adjusted; an intake throttle valve control means for controlling the opening and closing of the intake throttle valve in accordance with the operating state of the internal combustion engine; and an opening degree of the intake throttle valve targeted by the intake throttle valve control means. Pressure estimating means for estimating the pressure of the exhaust gas upstream of the exhaust gas purifying means, and an allowable value for calculating a range of pressures at which the intake throttle valve can be considered normal based on the pressure of the exhaust gas estimated by the pressure estimating means. And an abnormality determining unit that determines that the intake throttle valve is open / closed abnormally when the value detected by the pressure detecting unit is outside the range of the pressure calculated by the allowable value calculating unit. Abnormality determination device for an internal combustion engine, characterized. 11. When the value detected by the pressure detecting means is larger than the pressure range calculated by the allowable value calculating means, the abnormality determining means determines that the opening of the intake throttle valve is the intake air. When the opening degree required by the throttle valve control means is larger, while the value detected by the pressure detection means is smaller than the pressure range calculated by the allowable value calculation means, the intake throttle valve is opened. The abnormality determination device for an internal combustion engine according to claim 10, wherein the degree is determined to be smaller than the opening degree requested by the intake throttle valve control means. 12. Exhaust gas purification means for purifying harmful substances contained in exhaust gas, a differential pressure sensor for detecting a pressure difference between exhaust gas upstream and downstream of said exhaust gas purification means, and fresh air flowing in an intake system of an internal combustion engine. Of the intake throttle valve, an intake throttle valve control unit that controls the opening and closing of the intake throttle valve according to the operating state of the internal combustion engine, and an intake throttle valve that is targeted by the intake throttle valve control unit. And a pressure difference estimating means for estimating the pressure difference between the exhaust gas upstream and downstream of the exhaust gas purifying means, and the intake throttle valve is normal based on the pressure difference between the exhaust gases estimated by the pressure difference estimating means. Allowable value calculating means for calculating the range of possible pressure difference, and abnormal opening and closing of the intake throttle valve when the value detected by the differential pressure sensor is outside the range of pressure difference calculated by the allowable value calculating means. Difference to judge Abnormality determination device for an internal combustion engine, characterized in that it comprises a determining means. 13. When the value detected by the differential pressure sensor is larger than the range of the pressure difference calculated by the allowable value calculating means, the abnormality determining means determines that the opening degree of the intake throttle valve is the above-mentioned value. The intake throttle valve is larger than the opening degree requested by the intake throttle valve control means, while the value detected by the differential pressure sensor is smaller than the range of the pressure difference calculated by the allowable value calculation means. 13. The abnormality determination device for an internal combustion engine according to claim 12, wherein the opening degree is determined to be smaller than the opening degree requested by the intake throttle valve control means. 14. The particulate matter contained in the exhaust gas, wherein the exhaust gas purification means carries an NOx catalyst which stores NOx when the air-fuel ratio of the exhaust gas is lean and which reduces the stored NOx in the presence of a reducing agent. The internal combustion engine further comprises a reducing agent supply means for supplying a reducing agent to the filter, and the abnormality determining means supplies the reducing agent to the filter from the reducing agent supply means. The abnormality determination device for an internal combustion engine according to any one of claims 5 to 13, wherein the abnormality determination is performed when the abnormality is present. 15. The exhaust gas purification means is a filter capable of temporarily collecting the particulate matter contained in the exhaust gas, and the collection amount detecting means for detecting the collection amount of the particulate matter collected by the filter. Further, the abnormality determination means, the larger the amount of the particulate matter detected by the collection amount detection means, the larger the calculated value of the allowable value calculation means, the correction is made to determine the abnormality The abnormality determination device for an internal combustion engine according to any one of claims 5 to 14, which is performed.