JPH06264720A - After-exhaust processing device for diesel engine - Google Patents

Abstract

PURPOSE:To improve accelerative property under such driving conditions as high load range and high engine speed range by discontinuing regeneration in such ranges even if it is in the course of regeneration. CONSTITUTION:Running gears 24A, 24B and temperature-up device. 25A, 25B are controlled so that a regeneration control means 29 may regenerate a filter, designated this time, in accordance with the preset regeneration order when regeneration time has come by the judgement result of a regeneration time judgement means 28. A setting means 30 has set the high engine load range or the high engine speed range as a regeneration discontinuation range and a judgement means 31 makes judgement whether it is in the course of regeneration and the driving conditions is within the regeneration discontinuation range or not. Based on this judgement result, a regeneration discontinuation instruction means 32 instructs the regeneration control means 29 to discontinue regeneration when it is in the course of regeneration and the driving conditions is in the regeneration discontinuation range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust aftertreatment device for a diesel engine.

[0002]

2. Description of the Related Art When particulate matter discharged from a diesel engine is collected by a filter provided in an exhaust passage, pressure loss in the exhaust passage increases as the particulate matter accumulates in the filter, and operation during acceleration is increased. Since the influence on the property becomes large, it is necessary to regenerate the filter when the pressure loss exceeds a predetermined value.

Therefore, as in Japanese Patent Laid-Open No. 59-126018, the pressure loss is actually detected to judge whether or not it is time to regenerate, or in Japanese Patent Laid-Open No. 58-13115, the operation is performed. There is one that determines the time of reproduction from the history. At the time of regeneration, the filter is heated by a heating device such as a heater to raise the particulates to the combustion temperature, and the particulates deposited on the filter are incinerated and removed. During this regeneration, it is possible to perform regeneration more efficiently by shutting off the exhaust so that the heat for heating the particulates is not taken away by the exhaust, so most of the exhaust flows in the passage that bypasses the filter during regeneration. Some filters have been proposed that allow only a small amount of exhaust gas to pass through.

However, since the exhaust gas passes through the bypass passage during the regeneration of the filter, the particulate matter in the exhaust gas cannot be collected. Therefore, there is one in which the exhaust passage is branched into two and a filter is arranged in each of the branch passages.
At the time of regeneration, one of the branch passages is blocked and most of the exhaust gas is allowed to flow to the other branch passage to regenerate the blocked filter on the passage side, and the particulate matter of the exhaust flowing during regeneration is not blocked. Collect with a filter on the aisle side. When the regeneration of the filter on the side where the exhaust gas is blocked ends, at the time of the next regeneration, the branch passage that was flowing the exhaust gas at the time of the previous regeneration is blocked and the filter of that passage is regenerated, and it flows during the regeneration of this filter. Exhaust particulates are collected by the filter that has finished playing last time.

By thus dividing the filter into two parts, the particulate matter is prevented from being discharged without being collected even during the regeneration of the filter.

[0006]

By the way, when the filter is divided into two parts as described above, the volume of each filter is reduced to one in each exhaust passage in order to reduce the pressure loss during regeneration. It should be equivalent to the filter volume when a filter is provided.

However, in a comparatively small vehicle such as a passenger car, unlike a large-sized bus or truck, due to space restrictions, one filter volume on one side is provided with one filter in one exhaust passage. Since it is smaller than the filter volume, the pressure loss during regeneration is considerably large. For this reason, especially in the high rotation range and the high load range where the exhaust gas flow rate is large, the pressure loss becomes larger and the desired acceleration cannot be obtained even if the acceleration is attempted during regeneration.
When not playing, you get good acceleration,
The feeling of acceleration is greatly different between when the vehicle is being regenerated and when it is not being regenerated, resulting in a poor driving feeling.

It is possible to avoid this disagreement in acceleration feeling by making the judgment of the regeneration time relatively early, but in that case, the energy required for regeneration increases and the fuel efficiency deteriorates, so it is a good idea. Not.

Therefore, the object of the present invention is to improve the acceleration performance under these operating conditions by interrupting the regeneration under operating conditions such as a high load region and a high rotation region even during regeneration.

[0010]

As shown in FIG. 1, a first aspect of the invention is to provide a plurality of exhaust passages 21 (two shown in the figure) for branching passages 21A and 21B and each branch passage 21.
Filters 22A and 22B arranged on A and 21B,
Throttle valves 23A and 23B that open and close each branch passage, and devices 24A that drive these throttle valves 23A and 23B, respectively.
24B, devices 25A and 25B for respectively raising the temperature of the filters 22A and 22B, sensors 26 and 27 for respectively detecting the load and rotational speed of the engine, and a regeneration timing based on operating conditions determined from these sensor detection values. Means 28 for judging whether or not the driving device 24A, 24B and the temperature raising device 25A are so arranged that the filter designated this time is regenerated in accordance with a predetermined regenerating order when the regeneration time comes from this determination result. , 25
Means 29 for controlling B, means 30 for setting a high load region or a high rotation region of the engine as a regeneration interruption region, and whether or not the operating condition during regeneration and which is determined from the sensor detection value is the regeneration interruption region. Means 31 for determining
Based on the result of this determination, a means 32 is provided for instructing the regeneration control means 29 to suspend the regeneration when the regeneration is in progress and the operating condition is in the regeneration interruption area.

As shown in FIG. 2, the second aspect of the present invention is to provide a plurality of exhaust passages 21 (two in the figure) for branching the passages 21A and 21B, and filters disposed in the respective branch passages 21A and 21B. 22A, 22B, throttle valves 23A, 23B for opening and closing each branch passage, and these throttle valves 23A, 23
Device 24A, 24B for respectively driving B and device 25 for raising the temperature of each of the filters 22A, 22B respectively
A and 25B, sensors 26 and 27 for respectively detecting the load and engine speed of the engine, means 28 for judging whether or not the regeneration time has come based on the operating conditions determined from these sensor detection values, and from this judgment result At the time of regeneration, the drive unit 24A, so that the filter designated this time is regenerated in accordance with a predetermined regeneration order.
24B and a means 29 for controlling the temperature raising devices 25A, 25B, a means 30 for setting a high load region or a high revolution region of the engine as a regeneration interruption region, and an operating condition during regeneration and determined by the sensor detection value. A means 31 for judging whether or not the reproduction interruption area has been reached, and a means 32 for instructing the reproduction control means 29 to interrupt the reproduction when the reproduction is in progress and the operating condition is in the reproduction interruption area based on the result of this judgment.
A means 41 for calculating the frequency of the reproduction interruption by the reproduction interruption instruction means 32, and a means 42 for instructing the reproduction interruption instruction means 32 to prohibit the reproduction interruption when the frequency is a predetermined value or more are provided. .

[0012]

In the first aspect of the present invention, when the filters 22A and 22B continue to collect the particulates when the number of branch passages is two, the particulates deposited on the filters 22A and 22B gradually increase and the pressure loss increases.

When it is determined that the regeneration time has come based on the engine speed and the load, the regeneration control means 29 causes the drive units 24A and 24B and the temperature raising units 25A and 25B.
The regeneration of the filters 22A and 22B is alternately performed via the. For example, if the filter 22A is designated as the playback side this time, the throttle valve 23A is closed,
The temperature raising device 25A is operated.

On the other hand, when the throttle valve 22A is closed at the time of regeneration, the exhaust gas flowing through the branch passages flows together with the exhaust gas flowing through the remaining branch passages.
Both A and 22B have higher pressure loss than when they are open. When the engine operating conditions are particularly in the high load range and the high rotation range, the exhaust flow rate increases, so the pressure loss further increases, and the drivability deteriorates more.

In this case, in the first aspect of the invention, since the reproduction is interrupted in the high load range and the high rotation range, the acceleration of the vehicle when the driver depresses the accelerator pedal is in the regenerating state and the non-regenerating state. The same acceleration feeling as when not playing is obtained.

In the second aspect of the invention, the frequency of reproduction interruption is further calculated, and when the reproduction interruption is prohibited and the reproduction is performed when the frequency is equal to or more than the predetermined value, the reproduction is surely performed while obtaining a good feeling of acceleration. By prohibiting the interruption of the reproduction, the collection of the particulates is always carried out, but the reproduction is prevented from being disabled.

[0017]

EXAMPLE In FIG. 3, an exhaust passage 2 is branched into two, and filters 3A and 3B for collecting particulates from the engine 1 are arranged in the respective branch passages 2A and 2B. The filters 3A and 3B are adhered and collected types formed in a three-dimensional mesh shape.

In the branch passage 2A, a butterfly type throttle valve 4A is provided downstream of the filter 3A, and the throttle valve 4A is opened and closed by a drive unit 5A. Drive device 5A
Is composed of, for example, a diaphragm actuator connected to the throttle valve 4A and a three-way solenoid valve for switching control pressure to the diaphragm actuator.
In the state of F, the throttle valve 4A is at the fully open position, but when the solenoid valve is turned from OFF to ON, a constant negative pressure is introduced into the pressure chamber of the diaphragm actuator instead of the atmospheric pressure, and the throttle valve 4A is almost fully closed. It is closed to the position.

A heater 6 is provided just in front of the filter 3A.
When A is provided and the heater 6A is turned on, the filter 3A is heated to a temperature at which the particulate matter deposited on the filter 3A can burn.

Similarly, a heater 6B, a throttle valve 4B, and a drive device 5B for the throttle valve 4B are provided also on the side of the remaining branch passage 2B, and the two branch passages 2A2B join downstream of the throttle valves 4A, 4B. Has been done.

Reference numeral 11 is a sensor for detecting the number of revolutions of the fuel injection pump, and 12 is an accelerator sensor (for example, composed of a potentiometer) for detecting an accelerator opening (engine load equivalent amount). The engine speed Ne is calculated from the pump speed.

The signals from these sensors are input to the control unit 15 consisting of a microcomputer,
In the control unit 15, drive signals (ON and OFF signals to the three-way solenoid valve) are sent to the heaters 6 to the two drive devices 5A and 5B as shown in FIGS.
Energization signals are output to A and 6B, respectively.

The flowcharts of FIGS. 4 and 5 are executed at regular intervals (for example, every 10 msec).

First, the engine speed and accelerator opening are read in as preprocessing, and the deposition rate of particulates is obtained from these by searching a map having the contents of FIG. 6 (steps 1, 2, 3 in FIG. 4).

Whether or not the reproduction is requested is checked from the reproduction request flag and the like, and when the reproduction is not requested, the reproduction time is calculated (steps 4 and 5 in FIG. 4). In the calculation of this regeneration time,
The map value of the deposition rate is multiplied by the calculation cycle to calculate the deposition amount, and this is integrated. Since the unit of the deposition rate in FIG. 6 is g / h, the map amount is calculated by multiplying the map value by a value obtained by converting the calculation cycle of 10 msec into a time unit. As shown in FIG. 6, the speed is used as a unit so that the same map can be used even if the calculation cycle is different.

It is checked whether or not this regeneration time data (that is, the accumulated value of the accumulated amount) exceeds a predetermined threshold value, and if it exceeds the threshold value, a regeneration request command is issued and a regeneration process is performed (see FIG. 4). Steps 6 and 7).

On the other hand, when the reproduction request is made, the reproduction continuation time K is incremented (step 9 in FIG. 4). This reproduction continuation time K is necessary to judge the reproduction end, and when the reproduction continuation time K becomes equal to or more than a predetermined value, the reproduction end processing is performed (steps 11 and 12 in FIG. 5) to determine the reproduction continuation time K. Clear (step 15 in FIG. 5). The skipped steps 8, 10, 13, 14, 16 will be described later.

This reproduction end processing and the above-mentioned reproduction processing are the same as in the conventional case. For example, it is stored which filter reproduction process was performed last time, and this time, the filter reproduction process opposite to the previous time is performed. Now in FIG.
If the regeneration side is the filter 3A this time, at the start of regeneration, the branch passage 2A is blocked by the throttle valve 4A and most of the exhaust gas is flown to the other branch passage 2B, and the blocked filter 3A on the passage side is heated. While being regenerated by heating, the particulate matter of the exhaust flowing during the regeneration is collected by the filter 3B on the passage side which is not blocked. After continuing this for a certain period of time, the power supply to the heater 6A is stopped and the throttle valve 4A is opened.

At the next regeneration time, the branch passage 2B is shut off by the throttle valve 4B to regenerate the filter 3B in the passage, and the particulate matter of the exhaust gas flowing during the regeneration of the filter 3B depends on the end of regeneration. Collect with filter 3A. After continuing this for a certain period of time, the power supply to the heater 6B is stopped and the throttle valve 4B is opened.

As described above, the reproduction request flag is set by the reproduction request command, and this time, which side of the filter is reproduced is also instructed.

Now, in a relatively small vehicle such as a passenger car,
Due to space limitations unlike large buses and trucks, the volume of two filters combined is larger than the volume of one filter provided in one exhaust passage, but each filter 3A or 3B
The volume is smaller than the filter volume when one filter is provided in one exhaust passage, and the pressure loss during regeneration is considerably large.

This pressure loss increases as the exhaust pressure increases, so under operating conditions such as high load and high rotation,
It is preferable to suspend the regeneration so that drivability such as acceleration is not deteriorated. On the other hand, if the reproduction is interrupted too often, the reproduction may not be performed at all.

To deal with this, step 8 in FIG.
In steps 10 and 17 to 29 of FIG. 5, regeneration is interrupted under operating conditions such as high load and high rotation even when the regeneration of the filter is requested, and the frequency of regeneration interruption is calculated. Prohibit playback interruption and start playback.

More specifically, when a reproduction request is made, the reproduction request time T is incremented separately from the reproduction continuation time K (step 8 in FIG. 4). Since the reproduction may be interrupted even during the reproduction request, T represents the time from the start of the reproduction request including the reproduction interruption time.

Turning to FIG. 5, it is checked whether the reproduction interruption is prohibited by the reproduction interruption prohibition flag or the like (step 10 in FIG. 5). For example, if a flag indicating that the reproduction interruption is prohibited when the value is "1" and a cancellation of the reproduction interruption prohibition when "0" is prepared, the value of the flag is "0" when the reproduction request is made for the first time. Proceed to the reproduction interruption process after step 17.

Conditions for interrupting the regeneration are as follows: <1> The operating condition is in the regeneration interrupted region (step 17 in FIG. 5), <2> The regeneration interrupted region time matches the predetermined time (step 19 in FIG. 5). ) Are both satisfied (steps 17, 19, 21 in FIG. 5).

Whether or not it is in the reproduction interruption area of the condition <1> is determined by searching the map having the contents of FIG. As shown in FIG. 7, the high load range and the high rotation range are the reproduction interruption areas, and the frequency of the reproduction interruption is 1 during the reproduction request during the reproduction interruption area.
The boundary between the reproduction interruption area and the reproduction area is determined so that the reproduction interruption area and the reproduction interruption area are controlled.

The reproduction interruption area time of the condition <2> is the time after the reproduction interruption area is entered, and is incremented by the timer (steps 17 and 18 in FIG. 5). The condition <2> is a requirement because the reproduction interruption is not performed until the reproduction interruption area is entered transiently (temporarily).

When the reproduction interruption area time matches the predetermined time, the reproduction interruption time t is incremented and a reproduction interruption request is issued (for example, the value of the reproduction interruption flag is set to "1" by the reproduction interruption request. Value is used in step 29 as described later), and the reproduction interruption process is started (steps 19, 20, 21 in FIG. 5). The process of interrupting the regeneration is stopping the energization of the heater and opening the throttle valve. The reproduction interruption area time which becomes unnecessary at the start of the reproduction interruption is cleared (step 22 in FIG. 5).

When the reproduction is interrupted, the reproduction continuation time K
Is cleared (step 23 in FIG. 5). This is because if the reproduction is interrupted before the time is up, the reproduction ends midway, and when the reproduction interruption is prohibited after that, the reproduction process is started again.

If the reproduction interruption area time is shorter than the predetermined time, it means that the reproduction interruption is not in progress (that is, the value of the reproduction interruption flag is "0"), so that steps 20 to 23 are skipped (step 19, FIG. 5). 29, 24) and when the above predetermined time is exceeded, the reproduction interruption time t is continuously incremented because the reproduction is being interrupted (step 1 in FIG. 5).
9, 29, 20, 21, 22, 23).

On the other hand, when the operating condition is no longer in the reproduction interruption area, the reproduction interruption area time is cleared, and a reproduction interruption cancellation request is issued (the above-mentioned reproduction interruption flag value is returned to "0") to reproduce. Execute interruption cancellation processing (Fig. 5
Steps 17, 27, 28). As a result, the value of the reproduction interruption flag is again "0" (that is, the reproduction interruption is not in progress), and therefore the reproduction interruption time t is not incremented any more (steps 29 and 2 in FIG. 5).
4).

In this way, the reproduction interruption time t is incremented, and the reproduction interruption frequency is calculated from the reproduction interruption time t and the reproduction request time T by the formula of reproduction interruption frequency = t / T. When this exceeds a predetermined value, a command for prohibiting reproduction interruption is issued to execute reproduction interruption prohibition processing (steps 24, 25, 26 in FIG. 5). The reproduction interruption prohibition flag used in step 10 is set to "1". The driving condition in which the interruption of the regeneration is prohibited is, for example, a case where climbing or high-speed high-load driving continues for a long time.

Since the interruption of reproduction is prohibited during the reproduction request, the reproduction interruption start processing starts the reproduction processing. Next time, the reproduction request is made, the reproduction continuation time K is incremented again, and the reproduction processing is continued (steps 4, 8, 9 in FIG. 4 and steps 10, 1 in FIG. 5).
1). At the end of reproduction, the reproduction interruption time t is cleared and the reproduction interruption prohibition flag is set to "0" to cancel the reproduction interruption prohibition (steps 14 and 16 in FIG. 5).

The operation of this example will be described.

When both the throttle valves 4A and 4B are open, the particulates in the exhaust gas discharged from the engine 1 are collected by the filters 3A and 3B, and the cleaned exhaust gas is discharged to the rear part of the vehicle. It

When the filters 3A and 3B continue this collecting operation, the particulate matter deposited on the filters 3A and 3B gradually increases and the pressure loss increases.

In the control unit 15, the filters 3A and 3A are controlled based on the engine speed and the accelerator opening.
The particulate deposition amount of B is calculated, and when the value reaches the threshold value, the filters 3A and 3B are regenerated alternately.

Reproduction is performed by a filter on the reproduction side (for example, 3
It is started by closing the throttle valve 4A to shut off the exhaust gas flowing to (A) and energizing the heater 6A, but since the particulates do not burn until the combustion temperature is reached, the regeneration is completed in a short time. Difficult to do,
Relatively long time to finish playback (for example, about 20 minutes)
Requires.

On the other hand, when the throttle valve 4A is closed at the time of regeneration, twice the flow rate of exhaust gas flows through the branch passage 2B.
The pressure loss increases by a factor of four compared to when both of the two throttle valves 4A and 4B are open.

In this case, when the engine operating conditions are particularly high load and high speed, the exhaust gas flow rate increases, so the pressure loss further increases and the drivability at the time of acceleration becomes worse. When the driver depresses the accelerator pedal during reproduction, the vehicle is not accelerated due to the pressure loss, and a big discomfort occurs when acceleration is performed during non-reproduction.

On the other hand, in this example, since the regeneration of the filter is interrupted at the time of high load or high rotation, the acceleration of the vehicle when the driver depresses the accelerator pedal is different from that during regeneration. This is the same as when playing back, and the above-mentioned discomfort does not occur.

For example, reproduction is rarely interrupted when driving in an urban area or on a congested road. However,
Even in urban areas, under conditions where the driver temporarily requests acceleration, such as when climbing uphill or suddenly starting from a stop, acceleration can be ensured by interrupting playback, and playback will resume after acceleration has stopped. Be seen.

On the other hand, if the interruption of the reproduction is repeated too much, the particulates are always collected, but the reproduction may not be turned to the one direction.

In this case, in this example, the frequency at which the reproduction is interrupted during the reproduction is calculated, and when the frequency exceeds the predetermined value, the reproduction interruption is prohibited and the reproduction is performed. If the frequency of regeneration interruption exceeds a predetermined value, it is judged that the particulate accumulation rate is higher than the rate at which the particulates are burned and removed by regeneration, and the regeneration interruption prohibition (that is, regeneration) is set as the regeneration interruption command. It gives priority. As a result, regeneration is ensured while ensuring drivability during acceleration.

In the embodiment, the case where the number of branch passages is two has been described, but the case where the number of branches is three or more can be similarly applied.

[0057]

According to the first aspect of the present invention, a filter is provided in each of the passages that branch the exhaust passage, and each throttle valve opens and closes, a device that drives each throttle valve, and each of the filters. While providing each with a device for raising the temperature, it is determined whether or not the regeneration time has come based on the operating conditions that are determined from the engine load and the sensor detection value of the number of revolutions. According to the regeneration order, the drive unit and the temperature raising unit are controlled so that the filter designated this time is regenerated, and the high load region or the high revolution region of the engine is set as the regeneration interruption region, and the regeneration is being performed. When the operating condition determined from the sensor detection value falls within this regeneration interruption area, regeneration is interrupted, so there is a space constraint. As a result, good acceleration can be obtained even in a relatively small vehicle such as a passenger car in which the volume of the filter remaining excluding the filter to be regenerated is smaller than the volume of one filter provided in one exhaust passage. .

In addition to the first aspect of the invention, the second aspect of the present invention is further configured to calculate the frequency of reproduction interruption and to inhibit the reproduction interruption when the frequency is equal to or higher than a predetermined value to perform reproduction.
Unlike the first invention, the reproduction can be surely performed while obtaining the same favorable acceleration performance as that of the first invention.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the first invention.

FIG. 2 is a diagram corresponding to claims of the second invention.

FIG. 3 is a system diagram of an embodiment.

FIG. 4 is a flowchart for explaining a reproduction process.

FIG. 5 is a flowchart for explaining a reproduction process.

FIG. 6 is a characteristic diagram of a deposition rate of particulates.

FIG. 7 is a characteristic diagram showing a reproduction interruption area.

[Explanation of symbols]

 2 Exhaust passage 2A, 2B Branch passage 3A, 3B Filter 4A, 4B Throttle valve 5A, 5B Drive device 6A, 6B Heater (heating device) 11 Pump speed sensor (engine speed sensor) 12 Accelerator sensor (engine load sensor) 15 Control Unit 21 Exhaust Passage 21A, 21B Branch Passage 22A, 22 Filter 23A, 23 Throttle Valve 24A, 24B Driving Device 25A, 25B Temperature Raising Device 26 Engine Load Sensor 27 Engine Speed Sensor 28 Regeneration Timing Judging Device 29 Regeneration Controlling Means 30 Reproduction interruption area setting means 31 Reproduction interruption determination means 32 Reproduction interruption instruction means 41 Reproduction interruption frequency calculation means 42 Reproduction interruption prohibition instruction means

Claims (2)

[Claims] 1. A passage in which an exhaust passage is branched into a plurality of parts, a filter arranged in each branch passage, a throttle valve for opening and closing each branch passage, and a device for driving each of these throttle valves.
A device for respectively raising the temperature of each of the filters, a sensor for detecting the load and an engine speed of the engine, a means for determining whether or not the regeneration time has come based on operating conditions determined from these sensor detection values, and this determination From the result, when it comes to the regeneration time, the means for controlling the drive unit and the temperature raising device so that the filter designated this time is regenerated in accordance with the predetermined regeneration order, and the high load range or the high rotation range of the engine are set. Means for setting as a reproduction interruption area, means for judging whether or not the operation condition during regeneration and which is determined from the sensor detection value is this reproduction interruption area, and means for reproducing from the judgment result and the operation condition is the reproduction interruption area Then, a means for instructing the regeneration control means to interrupt the regeneration is provided, and the exhaust gas of the diesel engine is characterized. Processing apparatus. 2. A passage having a plurality of exhaust passages, a filter arranged in each branch passage, a throttle valve for opening and closing each branch passage, and a device for driving each throttle valve.
A device for respectively raising the temperature of each of the filters, a sensor for detecting the load and an engine speed of the engine, a means for determining whether or not the regeneration time has come based on operating conditions determined from these sensor detection values, and this determination From the result, when it comes to the regeneration time, the means for controlling the drive unit and the temperature raising device so that the filter designated this time is regenerated in accordance with the predetermined regeneration order, and the high load range or the high rotation range of the engine are set. Means for setting as a reproduction interruption area, means for judging whether or not the operation condition during regeneration and which is determined from the sensor detection value is this reproduction interruption area, and means for reproducing from the judgment result and the operation condition is the reproduction interruption area Then, the means for instructing the reproduction control means to interrupt the reproduction and the frequency of the reproduction interruption by the reproduction interruption instruction means are calculated. That means the exhaust aftertreatment system for a diesel engine, characterized in that the frequency and a means for instructing prohibition of playback interruption to the playback interrupt instruction means when a predetermined value or more.