JP2003343240A - Exhaust gas purifying device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas purifying device determining whether a reducing agent is properly supplied. <P>SOLUTION: An exhaust gas purifying system has an SCR catalyst 3 and a urea adding injector 5 for supplying the reducing agent to the SCR catalyst 3. It is judged that the exhaust gas purifying system is abnormal, when a vehicle travels for predetermined distance, in the case that an actual urea water consumption amount calculated from the urea water amount detected with a level sensor 11 does not meet the consumption judging value predicted from the travel of the predetermined distance. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

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

[0002]

Exhaust gas emitted from a diesel engine includes HC (hydrocarbon), CO (carbon monoxide), N
Contaminants such as Ox (nitrogen oxide) and PM (Particulate Matter) are included. Among these pollutants, NOx is difficult to purify with a three-way catalyst that is practically used in oxidation catalysts and gasoline automobiles, and selective reduction type NOx is a promising catalyst that can purify NOx.
x catalysts (hereinafter referred to as SCR catalysts) are being developed.

The SCR catalyst is a catalyst for purifying NOx in the presence of a reducing agent such as ammonia. The urea water added from the urea (urea) water tank to the exhaust system upstream of the SCR catalyst is hydrolyzed by the heat of the exhaust gas to generate ammonia. This ammonia is adsorbed on the catalyst surface of the SCR catalyst and reacts with NOx in the exhaust gas to purify NOx in the exhaust gas.

Here, as described above, NOx is purified by reacting NOx with ammonia. Therefore, if the supply of urea water is interrupted, the SCR catalyst will not exert its purification action. When the supply of urea water is cut off,
For example, the urea water stored in the tank may run out, and in such a case, the level sensor installed in the tank warns the driver to replenish the urea water.

[0005]

However, there is a risk that the driver will not notice even if the urea water is exhausted due to a malfunction of the level sensor itself, and there is no warning. In addition to the above-described cases where the supply of urea water is interrupted, there are cases where the urea water is clogged in the supply pipe through which the urea water passes from the tank until it is added to the exhaust system. This is because the urea dissolved in the urea water precipitates due to changes in temperature and concentration and blocks the supply pipe.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust gas purification apparatus for an internal combustion engine capable of determining whether or not urea water is appropriately supplied.

[0007]

In order to solve the above object, in the invention according to claim 1, a NOx catalyst for selectively reducing NOx in exhaust gas, and a reducing agent supply means for supplying urea water to the NOx catalyst. In the exhaust gas purification system having a control unit that controls the operation of the reducing agent supply unit according to the operating state of the internal combustion engine, a urea water consumption amount detection unit that detects the urea water consumption amount, and a travel distance of the vehicle The exhaust gas purification system is provided with a travel distance detecting means for detecting, and when the urea water consumption amount is smaller than a consumption amount determination value based on the travel distance, it is determined that the exhaust gas purification system has an abnormality.
Thus, the malfunction of the exhaust gas purification system can be detected and the occupant can be notified of the abnormality with a simple detection system.

The abnormality of the exhaust gas purification system includes, for example, clogging of the urea water supply passage due to urea deposition in urea water, failure of the level sensor of the urea water tank, and the like.

Further, the invention according to claim 2 is the same as the invention according to claim 1, further comprising temperature detecting means for detecting or estimating the exhaust gas temperature at the inlet of the NOx catalyst or the catalyst temperature of the NOx catalyst. The traveling distance detecting means detects the traveling distance in the operating state of the internal combustion engine in which the exhaust gas temperature or the catalyst temperature is equal to or higher than a predetermined temperature. Thereby, the malfunction of the exhaust gas purification system can be accurately detected with a simple detection system.

According to the third aspect of the invention, the NOx catalyst for selectively reducing NOx in the exhaust gas and the NOx.
In an exhaust gas purification system having a reducing agent supply means for supplying urea water to a catalyst and a control means for controlling the operation of the reducing agent supply means according to the operating state of an internal combustion engine, urea water for detecting the amount of urea water consumption A consumption amount detecting means and an operating state detecting means for detecting an operating state of the internal combustion engine,
When the urea water consumption amount is less than the consumption amount determination value based on the operating state, it is determined that the exhaust gas purification system has an abnormality. Thus, the malfunction of the exhaust gas purification system can be detected and the occupant can be notified of the abnormality with a simple detection system.

The invention according to claim 4 is the same as the invention according to claim 3, further comprising temperature detecting means for detecting or estimating the exhaust gas temperature at the inlet of the NOx catalyst or the catalyst temperature of the NOx catalyst. The operating state detection means detects an integrated operating time obtained by integrating the operating state time when the exhaust gas temperature or the catalyst temperature is equal to or higher than a predetermined temperature, and the integrated operating time is equal to or more than a predetermined time,
When the urea water consumption is less than the consumption determination value based on the predetermined time, it is determined that the exhaust gas purification system has an abnormality. Thereby, the malfunction of the exhaust gas purification system can be accurately detected with a simple detection system.

According to a fifth aspect of the present invention, in addition to the third aspect of the present invention, a fuel injection nozzle drive means for controlling the valve opening time of the fuel injection nozzle is further provided, and the operating state detection means is used for the operation. When the valve opening time is equal to or longer than the set time, the cumulative valve opening time is detected, and the cumulative valve opening time is equal to or longer than the predetermined time, and the urea water consumption is based on the predetermined time. When it is less than the determination value, it is determined that the exhaust gas purification system has an abnormality. Thereby, the malfunction of the exhaust gas purification system can be accurately detected with a simple detection system.

According to a sixth aspect of the invention, in the third aspect of the invention, there is further provided temperature detection means for detecting or estimating the exhaust gas temperature at the inlet of the NOx catalyst or the catalyst temperature of the NOx catalyst, A fuel injection nozzle driving means for controlling the valve opening time of the fuel injection nozzle, and the operating state detecting means integrates the valve opening time when the exhaust gas temperature or the catalyst temperature is equal to or higher than a predetermined temperature. Time is detected, and when the accumulated valve opening time is a predetermined time or more and the urea water consumption is less than the consumption determination value based on the predetermined time, it is determined that the exhaust gas purification system has an abnormality. As a result, the malfunction of the exhaust gas purification system can be detected more accurately with a simple detection system.

Further, in the invention according to any one of claims 1 to 6, the urea water consumption detected by the urea water consumption detecting means is the first urea just after the urea water is replenished to the urea water tank. The urea water consumption may be calculated by subtracting the second urea water amount immediately before the determination by the abnormality determining means from the water amount, and the determination may be performed by the abnormality determining means.

In some cases, the traveling distance of one operation is small, and the urea water consumption and traveling distance in a plurality of operations are integrated and used for the determination in the previous period abnormality determining means. In such a case, the correct judgment cannot be made if urea water is replenished to the urea water tank on the way, so if urea water is replenished before the judgment result comes out, the urea water consumption up to that point is consumed. Reset the accumulated value of amount and mileage, and make the judgment again from the beginning.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention. As shown in FIG. 1, the exhaust emission control device 1 includes an SCR catalyst 3, which is a NOx catalyst provided in the exhaust system of the engine 2, a urea water tank 4 for storing urea water, which is a reducing agent, and a urea water tank 4. Control valve 15 as a reducing agent supply means for supplying urea water to the supply pipe 14, the supply pipe 1
4, a urea-added injector 5 for supplying the urea water sent to the exhaust system to the exhaust system, a fuel injection nozzle 8 for supplying fuel to the combustion chamber of the engine, and a valve opening time of the fuel injection nozzle 8 for adjusting the fuel injection amount. The engine ECU 6 is a fuel injection nozzle driving means for controlling, a temperature sensor 7 is a temperature detecting means for detecting the temperature of the exhaust gas A before passing through the SCR catalyst 3, and a control unit 10 for controlling these devices. Further, the urea water tank 4 is provided with a level sensor 11 for detecting the amount of urea water and an electric heater 12 for preventing freezing of the urea water due to the outside temperature of the vehicle. In addition, information about the traveling distance of the vehicle detected by a traveling distance sensor (not shown), which is a traveling distance detecting means, is transmitted to the control unit 10, and the control unit 10 operates based on the transmission information to satisfy a certain condition. It is designed to calculate the mileage in the state.

The SCR catalyst 3 has a property that the NOx purification rate rapidly increases after the temperature of the exhaust gas A exceeds a predetermined temperature. For this reason, the control unit 10 which is a control means for controlling the operation of the control valve 15 includes the temperature sensor 7
Of the exhaust gas A detected by the engine ECU 6
The operating state of the engine, which is composed of information such as the valve opening time of the fuel injection nozzle 8 transmitted from the engine (functions as operating state detecting means), is detected, and the amount of NOx discharged from the engine 2 and the NOx catalyst are adsorbed. The supply amount of urea water is set according to the amount of ammonia present, and the operation of the control valve 15 is controlled.

The urea water supplied from the urea water tank 4 is mixed with the compressed air 13 in the mixing chamber 16 and, after passing through the supply pipe 14, is added from the urea addition injector 5 to the exhaust system on the upstream side of the SCR catalyst 3. It

Since the urea water passage in the mixing chamber 16 has a small diameter and the diameter of the injection hole of the urea-added injector 5 is small, urea in the urea water may be deposited at these locations and clogging may occur. Further, even if the level sensor 11 itself provided in the urea water tank 4 is out of order, for example, the occupant may not be aware that the urea water is exhausted, and as a result, the urea water may not be properly supplied. As described above, when the urea water is not properly supplied, the function of the SCR catalyst 3 for purifying NOx deteriorates or cannot be purified, as described above.

Therefore, the following five examples are used to determine whether or not the urea water is properly supplied. The control operations of the five embodiments will be specifically described below with reference to the drawings.

FIG. 2 is a flow chart showing the control operation by the control unit of the exhaust emission control device according to the first embodiment. As shown in the figure, first, step S20.
At 0, the mileage D is reset to zero and the current urea water amount Qf is read. That is, in determining whether or not urea water is appropriately supplied, the value of the traveling distance D recorded in the control unit 10 is set to zero and the level sensor 1 is set as an initial setting.
The current amount of urea water Qf in the urea water tank 4 detected by 1 is read and recorded in the control unit 10.

Next, in a series of controls starting from step S201, proceeding to steps S204 and S205 and returning to step S201 again, the traveling distance of the vehicle detected by the traveling distance sensor is measured and compared with the predetermined distance D0. At the same time, it is determined whether or not urea water has been replenished to the urea water tank 4 before the traveling distance D reaches the predetermined distance D0. That is, first, in step S201, it is determined whether or not urea water has been supplied to the urea water tank 4. If urea water is not replenished, the value of the travel distance D recorded in the control unit 10 is increased in accordance with the travel of the vehicle in step S204. Next, in step S205, the traveling distance D is compared with the predetermined distance D0. If the traveling distance D has not reached the predetermined distance D0, the process returns to step S201. Here, the predetermined distance D0 is a traveling distance where consumption of the predetermined amount Q0 of urea water is expected. Regarding the value of the predetermined distance D0, if the set value is made too large, it takes time to determine whether or not the urea water is appropriately supplied, while if it is made too small, the judgment error becomes large. Select an appropriate setting value.

On the other hand, in step S205, when the traveling distance D becomes equal to or more than the predetermined distance D0, step S2
Although the control proceeds to control after step 07, if it is determined in step S201 that the urea water is replenished by the time the predetermined distance D0 is reached, the process returns to step S200 and restarts from the initial setting. That is, when the urea water is replenished during the determination control, the determination control is restarted from the beginning.
The determination as to whether or not urea water has been replenished in step S201 is made, for example, by detecting removal of the cap of the urea water tank 4 or by detecting an increase in the amount of urea water by the level sensor 11.

After step S207, the predetermined distance D0
The urea water consumption expected based on the traveling of the vehicle is compared with the actual urea water consumption after traveling the predetermined distance D0, and it is determined whether or not the urea water is appropriately supplied. That is, first, the control unit 10, which is the urea water consumption amount detecting means, reads in the urea water amount Qr after traveling the predetermined distance D0 in step S207, and in step S208, the urea water amount Qf read in step S200 and the urea water amount Qr. The urea water consumption Qc is calculated from Next, in step S209, the control unit 10, which is the abnormality determining means, compares the urea water consumption amount Qc with the determination value Q. Here, the determination value Q is a value obtained by subtracting a constant threshold value from the urea water consumption amount Q0 (preliminarily set based on the results of a running test) expected when the vehicle travels the predetermined distance D0. In step S209, when the urea water consumption amount Qc is smaller than the determination value Q, it is determined that the urea water is not appropriately supplied for some reason, and in step S210, it is determined as “abnormal” and the occupant is warned. And so on. On the other hand, when the urea water consumption amount Qc is equal to or greater than the determination value Q, it is determined that the appropriate urea water supply is being performed, and the process ends.

FIG. 3 is a flow chart showing the control operation by the control unit of the exhaust purification system according to the second embodiment. As shown in the figure, first, in step S300, which is the initial setting, the traveling distance D is reset to zero and the current urea water amount Qf is read. The detailed description is similar to that of the first embodiment.

Next, in the series of controls in steps S301 to S305, the traveling distance of the vehicle under a certain condition is measured and compared with the predetermined distance D0, and the urea is reached before the traveling distance D reaches the predetermined distance D0. Determine if water has been replenished.

In step S301, it is determined whether or not urea water has been replenished. Without the supply of urea water,
In step S302, the exhaust gas temperature Gt detected by the temperature sensor 7 is read. Step S303
Then, the exhaust gas temperature Gt is compared with the predetermined temperature T1, and when the exhaust gas temperature Gt is equal to or higher than the predetermined temperature T1, the process proceeds to step S304, while when the exhaust gas temperature Gt is lower than the predetermined temperature T1, step S301. Return to. Here, the predetermined temperature T1 is a temperature at which the NOx purification of the SCR catalyst 3 has a predetermined purification rate, and is an exhaust gas temperature at which a certain amount of urea water is expected to be consumed. In step S304, the value of the traveling distance D recorded in the control unit 10 is increased according to the traveling of the vehicle. Next, in step S305, the traveling distance D and the predetermined distance D0 are compared, and if the traveling distance D has not reached the predetermined distance D0, the process returns to step S301. Here, the predetermined distance D0 is
It is a travel distance where consumption of a predetermined amount Q0 of urea water is expected.

On the other hand, in step S305, when the traveling distance D becomes equal to or greater than the predetermined distance D0, step S305
Although control proceeds to step 307 and thereafter, if it is determined in step S301 that urea water has been replenished by the time the predetermined distance D0 is reached, the process returns to step S300 and restarts from the initial setting.

That is, steps S301 to S305
In the above series of control, the traveling distance of the vehicle is measured in the driving state in which the exhaust gas temperature Gt is equal to or higher than the predetermined temperature T1, and when the traveling distance D is equal to or higher than the predetermined distance D0, step S3 is performed.
On the other hand, when the urea water is replenished before reaching the predetermined distance D0 while proceeding to 07, the determination control is performed again from the beginning.

After step S307, the control is the same as that after step S207 in the first embodiment. However,
In the first embodiment, the determination is made based on the amount of urea water consumed in traveling a certain distance regardless of the operating state of the engine, whereas in the second embodiment, the traveling is performed when the exhaust gas temperature is equal to or higher than a predetermined temperature. Judgment is based on the amount of urea water consumed for distance. Therefore, the determination accuracy is improved in the second embodiment, and the determination value Q in step S309 may be the consumption amount Q0 of urea water expected when the vehicle travels the predetermined distance D0, without providing a threshold value.

FIG. 4 is a flow chart showing the control operation by the control unit of the exhaust emission control device according to the third embodiment. As shown in the figure, first, as an initial setting, in step S400, the value of the operating time Td is reset to zero, and the current urea water amount Qf is read.
The operating time Td is an integrated operating time obtained by integrating the operating time of the engine under a certain condition.

Next, in the series of control from steps S401 to S405, the operating time of the engine under a certain condition is measured and compared with the predetermined time T0, and the operation time Td reaches the predetermined time T0. Determine if the urea water has been replenished.

In step S401, it is determined whether or not urea water has been replenished. Without the supply of urea water,
In step S402, the exhaust gas temperature Gt is read. In step S403, the exhaust gas temperature Gt is compared with the predetermined temperature T1, and the exhaust gas temperature Gt is compared with the predetermined temperature T.
If it is 1 or more, the process proceeds to step S404, while if the exhaust gas temperature Gt is lower than the predetermined temperature T1, the process returns to step S401. The predetermined temperature T1 is as described in the second embodiment. In step S404, the value of the operating time Td recorded in the control unit 10 is increased according to the operation of the engine. Then step S
In 405, the operating time Td is compared with the predetermined time T0, and if the operating time Td has not reached the predetermined time T0, the process returns to step S401. The predetermined time T0 is a predetermined amount Q0
It is the operating time of the engine that is expected to consume urea water.

On the other hand, in step S405, if the operating time Td is equal to or longer than the predetermined time T0, step S405
Although control proceeds to step 407 and thereafter, if it is determined in step S401 that urea water has been replenished by the time the predetermined time T0 is reached, the process returns to step S400 and restarts from the initial setting.

That is, steps S401 to S405
In the above series of control, the operating time in the operating state in which the exhaust gas temperature Gt is equal to or higher than the predetermined temperature T1 is measured, and the operating time Td
Is above the predetermined time T0, step S407
On the other hand, when the urea water is replenished before the predetermined time T0 is reached, the determination control is performed again from the beginning.

After step S407, the control is the same as that after step S207 in the first embodiment. However,
The determination value Q in step S409 may be the consumption amount Q0 of urea water expected when the engine is operated for the predetermined time T0 without setting a threshold value as in the second embodiment.

FIG. 5 is a flow chart showing the control operation by the control unit of the exhaust purification system according to the fourth embodiment. As shown in the figure, first, as an initial setting, in step S500, the value of the cumulative valve opening time T is reset to zero and the current urea water amount Qf is read. The cumulative valve opening time is a value obtained by integrating the valve opening time of the nozzle 8 that determines the injection amount when the fuel is injected from the fuel injection nozzle 8, and is a value that correlates with the fuel consumption amount.

Next, in a series of control from steps S501 to S505, the valve opening time Tn of the fuel injection nozzle 8 under a certain condition is integrated (integrated valve opening time T), and the predetermined time T
While comparing with 0, it is determined whether or not the urea water is replenished by the time the accumulated valve opening time T reaches the predetermined time T0.

In step S501, it is determined whether or not urea water has been replenished. Without the supply of urea water,
In step S502, the valve opening time Tn of the fuel injection nozzle 8 controlled by the engine ECU 6 is read. In step S503, the valve opening time Tn is compared with the set time T1, and if the valve opening time Tn is equal to or longer than the set time T1, the process proceeds to step S504, while if the valve open time Tn is shorter than the set time T1, the step is performed. Return to S501. Set time T
1 is a constant amount of urea water consumption (for example, an amount of about 5% of fuel consumption) that has a constant relationship with the fuel consumption amount (approximately proportional to the valve opening time Tn). Is the expected valve opening time of the fuel injection nozzle 8. Step S
At 504, the value of the integrated valve opening time T recorded in the control unit 10 is set to the valve opening time T of the fuel injection nozzle 8.
Increase according to n. Next, in step S505, the cumulative valve opening time T is compared with the predetermined time T0. If the cumulative valve opening time T has not reached the predetermined time T0, step S505
Return to 501. The predetermined time T0 is the “integrated value of the valve opening time” in which the consumption of the predetermined amount Q0 of urea water is expected.

On the other hand, in step S505, when the cumulative valve opening time T becomes equal to or longer than the predetermined time T0, the control proceeds to step S507 and thereafter, but it is determined that the urea water is replenished in step S501 before the predetermined time T0 is reached. If it is determined, the process returns to step S500 to restart from the initial setting.

That is, steps S501 to S505
In the above series of control, the valve opening time Tn of the fuel injection nozzle 8 is integrated with the valve opening time in the operating state of the set time T1 or more, and when the integrated valve opening time T becomes the predetermined time T0 or more, the process proceeds to step S507. On the other hand, if the urea water is replenished before the predetermined time T0 is reached, the determination control is restarted from the beginning.

After step S507, the control is similar to that after step S207 in the first embodiment. However,
The determination value Q in step S509 is the same as that in the second embodiment, without setting a threshold value, and as the consumption amount Q0 of urea water expected when the integrated value of the valve opening time Tn of the fuel injection nozzle 8 becomes the predetermined time T0. Good.

FIG. 6 is a flow chart showing the control operation by the control unit of the exhaust emission control device according to the fifth embodiment. As shown in the figure, first, as an initial setting, in step S600, the value of the cumulative valve opening time T is reset to zero, and the current urea water amount Qf is read. The detailed description is similar to that of the fourth embodiment.

Next, steps S601 to S6.
In a series of controls of 05, the valve opening time Tn of the fuel injection nozzle 8 under a constant condition is integrated (integrated valve opening time T) and compared with a predetermined time T0, and the integrated valve opening time T is set to the predetermined time T0. Determine whether or not the urea water was replenished before reaching.

In step S601, it is determined whether or not urea water has been replenished. Without the supply of urea water,
In step S602, the exhaust gas temperature Gt is read. In step S603, the exhaust gas temperature Gt is compared with the predetermined temperature T1, and the exhaust gas temperature Gt is compared with the predetermined temperature T.
If it is 1 or more, the process proceeds to step S604, while if the exhaust gas temperature Gt is lower than the predetermined temperature T1, the process returns to step S601. The predetermined temperature T1 is as described in the second embodiment. In step S604, the value of the integrated valve opening time T recorded in the control unit 10 is increased according to the valve opening time Tn of the fuel injection nozzle 8. Next, in step S605, the cumulative valve opening time T is compared with the predetermined time T0, and if the cumulative valve opening time T has not reached the predetermined time T0, the process returns to step S601. Predetermined time T0
Is the "integrated value of the valve opening time" in which the consumption of the predetermined amount Q0 of urea water is expected.

On the other hand, in step S605, when the cumulative valve opening time T becomes equal to or longer than the predetermined time T0, the control proceeds to step S607 and thereafter, but it is determined that the urea water is replenished in step S601 by the time the predetermined time T0 is reached. If it is determined, the process returns to step S600 to restart from the initial setting.

That is, steps S601 to S605
In the above series of control, the valve opening time Tn of the fuel injection nozzle 8 in the operating state where the exhaust gas temperature Gt is equal to or higher than the predetermined temperature T1
When the integrated valve opening time T is equal to or longer than the predetermined time T0, the process proceeds to step S607, while when the urea water is replenished before reaching the predetermined time T0, the determination control is performed again from the beginning.

After step S607, the control is the same as that after step S207 in the first embodiment. However,
The determination value Q in step S609 is the same as that of the second embodiment, and the threshold value is not set, and the amount of urea water consumption Q0 expected when the integrated value of the valve opening time Tn of the fuel injection nozzle 8 becomes the predetermined time T0 is set. Good.

The present invention is not limited to the above embodiment,
For example, the determination result obtained by the abnormality determining means may be recorded in a memory such as the engine ECU. This makes it possible to detect OBD during periodic inspections of vehicles.
It is possible to properly understand the failure of the exhaust gas purification system.

[0050]

According to the exhaust gas purifying apparatus for an internal combustion engine of the first aspect of the present invention, when the vehicle travels a predetermined distance (for example, a distance where consumption of urea water of a preset amount is expected), If the urea water consumption is less than the expected consumption value (for example, half the expected consumption value) from running a predetermined distance, it is determined that the exhaust gas purification system is abnormal. A simple detection system can detect a malfunction in the exhaust gas purification system.

Further, according to the exhaust gas purifying apparatus for an internal combustion engine of the second aspect of the present invention, when the exhaust gas temperature or the catalyst temperature is higher than or equal to a predetermined temperature, the vehicle is at a predetermined distance (that is, a constant urea water consumption is constant). If the actual consumption of urea water does not reach the expected consumption amount judgment value when traveling for a predetermined distance when traveling for a certain distance, it is determined that the exhaust gas purification system has an abnormality. It is possible to detect a malfunction of the exhaust gas purification system by using such a detection system.

Further, according to the exhaust gas purifying apparatus for an internal combustion engine according to the invention of claims 3 to 6, the actual urea water consumption amount is the exhaust gas temperature and the valve opening time of the fuel injection nozzle, or
When the consumption judgment value based on the operating state such as the valve opening period (fuel injection amount) and valve opening time of the fuel injection nozzle is not satisfied,
Since it is determined that there is an abnormality in the exhaust gas purification system, it is possible to detect a defect in the exhaust gas purification system with a simple detection system.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an exhaust emission control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control operation by a control unit of the exhaust emission control device according to the first embodiment.

FIG. 3 is a flowchart showing a control operation by a control unit of the exhaust emission control device according to the second embodiment.

FIG. 4 is a flowchart showing a control operation by a control unit of the exhaust emission control device according to the third embodiment.

FIG. 5 is a flowchart showing a control operation by a control unit of the exhaust emission control device according to the fourth embodiment.

FIG. 6 is a flowchart showing a control operation by a control unit of the exhaust emission control device according to the fifth embodiment.

[Explanation of symbols]

3 SCR catalyst 7 Temperature sensor 8 Fuel injection nozzle

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Claims (6)

[Claims] 1. NOx provided in an exhaust system of an internal combustion engine for adsorbing ammonia to selectively reduce NOx in exhaust gas.
A catalyst and a reducing agent supply means for supplying urea water as a reducing agent to the upstream side of the NOx catalyst in the exhaust system,
An exhaust gas purification system having a control unit that controls the operation of the reducing agent supply unit according to the operating state of the internal combustion engine, and urea water that is provided in a urea water tank that stores the urea water and that detects urea water consumption Consumption amount detecting means, mileage detecting means for detecting a mileage of a vehicle equipped with the internal combustion engine, and urea water consumption amount detected by the urea water consumption detecting means is detected by the mileage detecting means. An exhaust emission control device for an internal combustion engine, comprising: abnormality determination means for determining that the exhaust emission control system has an abnormality when the consumption amount is less than the determined consumption amount based on the traveled distance. 2. The exhaust emission control device for an internal combustion engine according to claim 1, further comprising temperature detection means for detecting or estimating an exhaust gas temperature at an upstream inlet of the NOx catalyst or a catalyst temperature of the NOx catalyst, The exhaust distance of the internal combustion engine, wherein the travel distance detecting means detects a travel distance in an operating state of the internal combustion engine in which the exhaust gas temperature or the catalyst temperature detected or estimated by the temperature detecting means is equal to or higher than a predetermined temperature. Purification device. 3. NOx provided in an exhaust system of an internal combustion engine to adsorb ammonia to selectively reduce NOx in exhaust gas.
A catalyst and a reducing agent supply means for supplying urea water as a reducing agent to the upstream side of the NOx catalyst in the exhaust system,
An exhaust gas purification system having a control unit that controls the operation of the reducing agent supply unit according to the operating state of the internal combustion engine, and urea water that is provided in a urea water tank that stores the urea water and that detects urea water consumption Consumption amount detecting means, operating state detecting means for detecting the operating state of the internal combustion engine, urea water consumption detected by the urea water consumption detecting means, in the operating state detected by the operating state detecting means An exhaust emission control device for an internal combustion engine, comprising: abnormality determination means for determining that the exhaust emission control system has an abnormality when the consumption amount is smaller than the consumption determination value. 4. The exhaust gas purification device for an internal combustion engine according to claim 3, further comprising temperature detection means for detecting or estimating the exhaust gas temperature at the upstream inlet of the NOx catalyst or the catalyst temperature of the NOx catalyst, The operating state detecting means detects an integrated operating time obtained by integrating the operating state time when the exhaust gas temperature or the catalyst temperature detected or estimated by the temperature detecting means is equal to or higher than a predetermined temperature, and the abnormality determining means is The exhaust gas of the internal combustion engine is determined to be abnormal when the urea water consumption amount is less than a consumption amount determination value based on the predetermined time period and the integrated operation time is a predetermined time period or more. Purification device. 5. The exhaust gas purification apparatus for an internal combustion engine according to claim 3, further comprising fuel injection nozzle drive means for controlling a valve opening time of a fuel injection nozzle that supplies fuel to a combustion chamber of the internal combustion engine, The operating state detecting means detects an integrated valve opening time obtained by integrating the valve opening time when the valve opening time by the fuel injection nozzle driving means is a set time or more, and the abnormality determining means determines the integrated valve opening time. Is a predetermined time or more and the urea water consumption is less than the consumption determination value based on the predetermined time, it is determined that the exhaust purification system is abnormal. 6. The exhaust gas purification device for an internal combustion engine according to claim 3, further comprising temperature detection means for detecting or estimating the exhaust gas temperature at the upstream inlet of the NOx catalyst or the catalyst temperature of the NOx catalyst, and A fuel injection nozzle driving means for controlling a valve opening time of a fuel injection nozzle for supplying fuel to a combustion chamber of the internal combustion engine, wherein the operating state detecting means is an exhaust gas temperature or a catalyst temperature detected by the temperature detecting means. Is equal to or higher than a predetermined temperature, the integrated valve opening time obtained by integrating the valve opening time by the fuel injection nozzle driving means is detected, and the abnormality determining means determines that the integrated valve opening time is equal to or longer than a predetermined time, and the urea water consumption An exhaust emission control device for an internal combustion engine, wherein when the amount is smaller than a consumption determination value based on the predetermined time, it is determined that the exhaust emission control system has an abnormality.