JPH05288039A - Exhaust gas purifying device for diesel engine - Google Patents

Abstract

PURPOSE:To lighten the burden of an electric heater for regeneration process of a filter to collect particulates and execute efficient regeneration, concerning an exhaust gas purifying device of a diesel engine. CONSTITUTION:An elapsed time T from stop during regeneration to restart is measured by means of the timer clock 12g of an ECU 12, and only when the time is shorter than a prescribed time Ta, regeneration of the filter is executed after restart, and when the time is longer than it, re-collecting is executed. Hereby waste of a heat quantity is reduced. Meanwhile, because the shorter the elapsed time T is, the higher the temperature of the filters 2, 3 is, electrifying time of a heater at restart can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device provided in a diesel engine, and more particularly to an exhaust gas purification device having an exhaust system provided with a filter for collecting particulates in exhaust gas.

[0002]

2. Description of the Related Art In general, exhaust gas of a diesel engine contains a large amount of exhaust particulates, that is, particulates. Therefore, the exhaust system of the engine has a particulate filter (hereinafter referred to as a filter) for collecting the particulates. Called) is installed.

Further, in this filter, if the amount of particulates accumulated inside the filter increases with use, the air permeability is gradually deteriorated and the engine performance deteriorates. Therefore, depending on the particulate collection amount. It is played back regularly. The filter regeneration is performed by activating the so-called regeneration heating means such as an electric heater provided in the vicinity of the end face of the filter or an electric air pump for supplying the air required for particulate combustion. And again to ensure the breathability of the filter.

Therefore, if the engine operation is stopped (engine key-off) during filter regeneration, the operation of the regeneration heating means described above is also stopped, and the filter is in an incomplete regeneration state. Therefore, at the time of restart, if the particulate collection is restarted in this state, a problem such as a reduction in collection efficiency will occur.

In order to deal with such a problem as described above,
In Japanese Utility Model Laid-Open No. 1-139015, a timer is started along with the start of filter regeneration, and if the engine operation is stopped during regeneration, the remaining time of the timer is stored, and at the time of restart, the regeneration operation is performed by the remaining time. An apparatus for performing is disclosed.

[0006]

However, when the engine operation is stopped in the middle of the regeneration as described above, after the engine is restarted,
In the case of a device that immediately starts the regenerating operation, there may be a case where it is difficult to regenerate because the load on the regenerating heating means is large.
Also, depending on the length of time from the time of operation stop to the time of restart, if the filter is heated with the same amount of heat generation as at the time of restart, useless heat will be consumed, and regeneration will be inefficient. Not preferred.

In view of such problems of the exhaust gas purification device, the present invention provides an exhaust gas purification device which can reduce the load on the regeneration heating means and reduce the waste of heat quantity to achieve efficient regeneration. The purpose is that.

[0008]

In order to achieve the above object, according to the present invention, a filter provided in an exhaust system of a diesel engine for collecting particulates in exhaust gas and a filter is heated during filter regeneration. Regeneration heating means for igniting and burning the particulates, means for detecting the passage of time from when the engine is stopped during engine regeneration until engine restart, and when the elapsed time is shorter than the predetermined time, There is provided an exhaust gas purification device which has filter regeneration control means for continuing filter regeneration after startup and for collecting particulates again after restart when the elapsed time is longer than a predetermined time.

Further, according to the present invention, in the above exhaust emission control device, further, there is provided means for detecting a temperature of the filter, and the filter operation control means has a short elapsed time and when the filter temperature at engine restart is equal to or higher than a predetermined temperature. Provided is an exhaust gas purification device which continues filter regeneration and collects particulates when the temperature is below a predetermined temperature.

In order to solve the same problem in the present invention, in addition to the above exhaust gas purification device, an exhaust gas purification device further comprising a filter for collecting particulates and a regeneration heating means for heating the filter at the time of regeneration of the filter, A means for detecting the passage of time from when the engine is stopped during filter regeneration until the engine is restarted, and a regeneration heating control that reduces the heating amount of the regeneration heating means after restart as the detected elapsed time becomes shorter. An exhaust emission control device is provided which is provided with a means.

[0011]

When the elapsed time from the stop of the engine during regeneration to the restart is short, the temperature of the filter is expected to be relatively high, and it is possible to easily regenerate even with a small amount of heat. Therefore, in the former exhaust emission control device, regeneration is performed after restart only when the elapsed time is shorter than the predetermined time, and when it is long, it is recollected without being regenerated, so that the amount of heat is not wasted.

Further, in the present invention as set forth in claim 2, finer control becomes possible by adding the filter temperature in addition to the conditions of the above apparatus, the waste of heat quantity can be further reduced, and the collection can be continued. In this case, defective reproduction is prevented.

Further, in the exhaust gas purification device according to the third aspect, the shorter the elapsed time is, the smaller the heating amount of the regenerative heating means is, so that the waste of the heat amount is small.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. With reference to FIG. 1 showing a schematic configuration of an exhaust emission control device according to the present invention, 1 is an exhaust pipe through which exhaust gas from an engine body (not shown) to be located on the left side in the drawing flows, 2
Reference numerals 3 and 3 denote a first filter and a second filter for collecting particulates in the exhaust gas, and reference numerals 4 and 5 branch the exhaust gas flowing in the exhaust pipe 1 into two parts, the first filter 2 and the second filter 3. It is the 1st and 2nd branch pipe which leads to.

In this embodiment, the exhaust gas passage defined by the exhaust pipe 1 is used as the exhaust passage 6, and the exhaust gas passage defined by the first branch pipe 4 and the second branch pipe 5 is branched. We will call them passages 7 and 8.

As a means for regenerating and heating the filters, an electric heater near the end faces on the exhaust gas upstream side of each of the filters 2 and 3 or near the end thereof is used to heat the filters 2 and 3 during filter regeneration to ignite particulates. 9 and 10 are provided, electric power is supplied to the electric heaters 9 and 10 from a battery 11, and energization is controlled by a heater relay 13 operated by a control circuit (ECU) 12.

Further, in this embodiment, the filter 2 or 3 to be regenerated at the time of regenerating the filter is provided in each of the first branch pipe 4 and the second branch pipe 5 located on the exhaust upstream side of the filters 2 and 3.
Against the regeneration gas for particulate combustion (2
Gas supply pipes 14a and 14b for supplying (secondary air) are connected, and they are joined to form a supply pipe 14 and connected to an electric air pump 15. Like the electric heater, the electric air pump 15 is also driven and controlled by the ECU 12, and the supply pipe 14 is provided with an opening / closing valve 16 that opens the pipe passage when the filter is regenerated.

Gas supply pipes 14a, 14b and branch pipes 4,
At the time of regeneration of the corresponding filter, the branch passages 7 and 8 are cut off from the exhaust passage 6 and the gas supply pipes 14a and 14b are opened to the branch passages 7 and 8 at the respective connection portions with the corresponding filter 5. The first to send regeneration gas to
The exhaust control valve 17 and the second exhaust control valve 18 are provided. The exhaust control valves 17 and 18 are respectively connected to the ECU 12
The actuators 19 and 20 are driven and controlled by

The ECU 12 is constructed as a microcomputer, for example, and outputs signals for driving the above-mentioned control valves, electric heaters, electric air pumps, etc., and A / D signals from respective sensors for detecting operating conditions described later. Input / output port (I /
O) 12b, and the CPU 12
c, ROM 12d, RAM 12e, B-RAM (backup ram) 12f that holds information even after the key switch 21 is turned off, and timer clock 12g are provided.
These are interconnected by a bus 12h.

On the input side of the above-mentioned input / output port 12b, in addition to the sensor shown, various sensors for providing information necessary for normal engine operation control are connected. Only the sensors related to are described.

That is, at this port 12b, a pressure sensor 22 for detecting the differential pressure across the filter ΔP necessary for determining the filter regeneration timing, a temperature sensor 23 for detecting the temperature t of the exhaust gas entering the filter, and a heater. Temperature sensors 24a, 24b for detecting the filter temperature tf in the vicinity are connected, and in addition, a rotation speed sensor for detecting the engine rotation speed Ne,
Output signals are also input from an air amount sensor that detects the intake air amount Ga, a water temperature sensor that detects the engine water temperature Thw, and an accelerator opening sensor. Of these signals, the analog signal is converted into a digital signal by the A / D converter 12a.

The operation of the exhaust gas purifying apparatus having the above-described structure at the time of filter regeneration is the same as that of the conventional one,
The differential pressure ΔP 'across the filter standardized under predetermined operating conditions by the intake air amount Ga, the engine speed Ne, and the exhaust temperature t.
Exceeds a predetermined value, and the ECU 12 determines that it is the time to regenerate the filter, the first exhaust control valve 17 of the first filter 2 is first closed, then the electric heater 9 is energized to heat the filter 2, and substantially at the same time. The electric air pump 15 is started to be driven, the regeneration gas is supplied to the filter 2, and the particulates are ignited and burned. When the regeneration process of the first filter 2 is completed, the regeneration of the second filter 3 is executed in the same manner.

The operation of the ECU 12, which is a feature of the present invention, will be described below with reference to FIGS. 2 and 3. FIG. 2 is a flowchart showing the operation of the ECU until the timer clock 12g in the ECU 12 is operated when the engine key is turned off and the operation of the engine is stopped during the series of filter regeneration described above. Therefore, it is premised that the ECU 12 that executes this program continues to operate even if the key is turned off.

Referring to FIG. 2, first, in step S1, it is determined whether or not the filter is currently being regenerated. The specific processing content here corresponds to, for example, detecting the presence or absence of the drive signal output of the electric air pump 15 or the exhaust control valves 17 and 18, and in the case of the dual filter as in the present embodiment, which one is used? It also includes the identification of whether the filter 2 or 3 of 1 is being reproduced. In the case of No, the following steps are skipped and this routine is finished.

If Yes in step S1, that is, if the filter is being regenerated, the routine proceeds to step S2,
This time, it is determined whether or not the corresponding electric heater 9 or 10 is being energized. Then, if the electric heater is being energized (corresponding to the previous period of the filter regeneration processing), the electric heater energization flag Fa is set to 1 in the subsequent step S3, and conversely it is estimated that the filter regeneration processing is in the latter half because it is not energized. If so (No), the filter regeneration flag F is set to 1 in step S4. Incidentally, these flags are used when executing the program of FIG. 3 described later.

Step S5 following step S3 or S4
Then, it is determined whether or not the engine key is currently turned off. When the engine key is off, that is, when the engine is stopped (Yes), the process proceeds to step S6, where the timer clock 12
If the engine key is not turned off by executing the process for starting g, the steps S3 and S4 are executed in step S7.
This resets the flags Fa and F set in step 1 to 0 and ends this routine.

That is, this routine described above determines whether or not the engine operation is stopped during filter regeneration, and if it is stopped, a flag set indicates at what point in the regeneration process the engine was stopped. As long as the elapsed time is measured from the time of stopping to the time of restarting, it is provided for two purposes.

Next, the flow chart shown in FIG. 3 will be described. This flow chart shows
The operation is executed when the engine key 21 is turned on, and the operation of the ECU 12 that determines and executes the filter operation mode at the time of restart based on the information provided by the above-described program will be described.

When the engine key 21 is turned on and the program starts, first in step S11, the above-mentioned flag Fa or F is set to 1 to determine whether or not this engine stop was performed during filter regeneration. It is determined by whether or not

If No is determined in this step, that is, if the flags Fa and F are both set to 0, the previous filter regeneration has been completed, and the following steps are skipped. To end this program. In this case, the filters 2 and 3 continue to perform the particulate trapping process.

On the other hand, if Yes at step S11, the routine next proceeds to step S12, where the value of the timer T started at the previous step S6, that is, the elapsed time T from the stop to the current restart is read. .. Then, in a succeeding step S13, it is determined whether or not the period from the engine stop to the restart is extremely short depending on whether the elapsed time T is within a first predetermined time Ta (for example, 60 seconds). judge.

If it is determined Yes in step S13 and the present start is performed in a short time after the engine operation is stopped, the process proceeds to step S14, and conversely, if No is determined, the filter regeneration is performed. Since it has been determined that the filters 2 and 3 have already been cooled since the elapse of time from, the electric heater 9,
Since it is expected that the load on 10 will be heavy, the following steps are skipped and this program ends.

In step S14 subsequent to step S13, it is determined whether or not the filter regeneration process interrupted during regeneration as described above is in the process of energizing the electric heater.
That is, the determination here is to see whether or not Yes in step S11 is due to the flag Fa = 1,
If Yes in step S14, that is, if the engine operation is stopped while the electric heater is energized, the electric heaters 9 and 10 still reach particulate ignition (in most cases, although it depends on the set heater energization time). Since it is expected that the particulates are not sufficiently heated and the particulates are not burned, the routine proceeds to step S15 to restart the energization as it is, and the reenergization time Th to the electric heaters 9 and 10 is calculated here. ..

Regarding the energization time calculation formula, a predetermined energization time for continuously energizing for one regeneration of the filter is T
t, where Ts is the energization time until the reproduction interruption, for example, [Equation 1] Th = 0.5 · Ts + (Tt-Ts) (Equation 1), with respect to the remaining energization time Tt-Ts, Half of the time Ts that has already been energized may be increased to compensate for the heater cooling amount while the engine is stopped, or the shorter the engine stop time T is, as shown in the following equation (2). It is also possible to correct the energization time Th according to the length of the time T such that the amount of decrease in the filter temperature is small and therefore the energization time also decreases.

[Equation 2] Th = aT (Tt-Ts) (Equation 2) where a: heater energization correction coefficient, T ≠ 0

In order to calculate the re-energization time, as a matter of course, the heater energization time Ts in the filter regeneration process which has been interrupted is B- of the ECU 12.
It must be stored in RAM 12f.

When the re-energization time Th is obtained as described above, the routine continues to step S16, where the input / output port 12b of the ECU 12 causes the corresponding electric heaters 9 and 10 of the filters 2 and 3 to be regenerated. On the other hand, when the energization is restarted, the corresponding exhaust control valves 17 and 18 are driven,
At the same time, the electric air pump 15 is restarted to restart a series of filter regeneration processes, and the present routine ends.

On the other hand, if it is determined No in step S14 and the interrupted filter regeneration process is after the electric heater energization is completed, and it is estimated that the particulates have already been ignited at the time of the interrupt. The routine then proceeds to step S17, where it is determined whether the engine stop time T is smaller than the second predetermined time Tb which is shorter than the first predetermined time Ta, and whether or not the time elapses. It is determined whether or not it is a short period (for example, less than 20 seconds) so that the curated flame does not disappear.

Then, it is determined No in step S17,
If it is estimated that the particulate flame has already disappeared, the distance between the electric heaters 9 and 10 and the unburned particulates is long even if the filter regeneration process is restarted, and a large amount of electric power is required for the ignition. Since it is expected to be consumed, the following steps are skipped and the present routine is ended without executing the regeneration processing (particulate collecting operation).

On the contrary, if it is determined Yes in step S17 and it is estimated that the particulate flame has not disappeared yet, the routine proceeds to step S18 and the electric air pump is not energized to the electric heaters 9 and 10. 15
Is output again to restart the filter regeneration process (continue filter regeneration operation). This step S
The re-driving of the electric air pump in 18 is executed for a time substantially equal to the remaining regeneration time of the previous time, and in supplying the secondary air, the supply amount of the secondary air is gradually increased to rapidly supply the secondary air. Care should be taken so that the particulate flame does not blow out.

As described above, according to this flowchart, the elapsed time T from the stop of the engine during the filter regeneration to the restart of the engine is detected by the clock timer 12g in the ECU 12, and this time T is set to the first value in step S13. Predetermined time Ta
When it is longer, the regeneration process at restart is stopped and the particulate collection process is executed again. On the contrary, when it is shorter than the predetermined time Ta, the filters 2, 3 and the electric heater 9, which have not been lowered so much, Since the temperature of 10 is used and the filter regeneration process is continued again in steps S16 and S18, the so-called efficient filter regeneration process can be performed with less waste of heat.

In addition, in this flowchart, the elapsed time T is shorter than the first predetermined time Ta, as shown in the electric heater energization time calculation execution process (steps S15 and S16) when it is determined Yes in step S13. In the regeneration process in this case, the time Ts which has already been energized is subtracted, or the shorter the engine stop time T is, the shorter the energization time during regeneration is to reduce the waste of heater energization. When the stop time T at that time is shorter than the second predetermined time Tb, the energization itself is stopped, so that the power consumption can be reduced as a whole, and in this sense, the regeneration is more efficient than in the past. Processing can be achieved.

Next, another embodiment different from the embodiments described with reference to FIGS. 2 and 3 will be described. In this embodiment, the filter regeneration progress state at the time of engine shutdown due to engine key-off or engine stall is subdivided and distinguished from the previous embodiment,
In accordance with this, the processing content at the time of stop or the processing content at the time of restart is regulated to a more specific low level.In addition to the elapsed time from the operation stop to the restart as a control parameter, The filter temperature at that time is also added to the processing content.

FIG. 4 is a time chart of a series of filter regeneration processes in the above-described exhaust gas purification apparatus. Here, as shown in the figure, a pre-treatment period in which secondary air is supplied to each filter prior to energization of the heater, It is divided into a total of 6 periods: heater energization period and combustion propagation period,
The present embodiment defines the regeneration period when the engine is stopped, the subsequent processing in each, and the processing operation at the time of restart.

The flow chart shown in FIG. 5 corresponds to the flow chart of FIG. 2 of the previous embodiment, and when the engine key is off or the engine stalls unintentionally during the filter regeneration, the timer clock 12 of the ECU 12 is set.
It is a program for operating g and storing for what kind of regeneration period the engine operation was stopped for the processing at the time of the next restart.

Explaining this program, first, in step S21, it is determined whether or not the filter is currently being reproduced. If No, the following steps are skipped and this routine is terminated (return). If YES is determined in the step S21 and the filter regeneration is currently being performed, the routine proceeds to a step S22, and it is determined which period is currently in the chart of FIG. 4 by, for example, the elapsed time from the start of the regeneration or the ECU 12. Is determined from the output signal or the like and stored by a method such as flag setting (for example, in the case of a period, flag F ₁ = 1).

Then, in the subsequent step S23, during such filter regeneration, the engine speed N is read, and it is determined whether or not N = 0 rpm at present, that is, whether or not the operation is stopped by the engine key-off or the engine stall. To be judged. And when the engine is stopped (Yes),
In step S24, it is determined whether or not the filter regeneration period shown in FIG.

On the other hand, if Yes in this step S24, that is, if the particulate ignition has already been achieved, it is better to continue the regeneration as it is, so step S25.
Then, the regeneration is continued, that is, the secondary air is supplied for a predetermined time, and the regeneration completion of the entire apparatus is stored (for example, the flag F ₆ is reset) only when the regeneration is continued during the regeneration period, and this routine is terminated.

On the other hand, if No is determined in step S24, it means that the operation stop has occurred at any one of the periods, and, so the routine proceeds to step S26, and at the time of restart described later. Because of each processing of
The timer clock 12g is started to perform processing for measuring the elapsed time T from engine stop to restart, and in step S27, the filter temperature tfs at the time of operation stop is detected, and this routine is ended.

On the contrary, in step S23, No,
That is, if the engine operation is not currently stopped, the routine proceeds to step S28, where the processing for clearing the regeneration period stored in the previous step S22 (for example, resetting the flag) is executed and this routine is ended. .. Figure 6
Explains the exhaust purification device operation mode executed at the time of engine (re) starting, based on the information on the filter regeneration provided by the above-mentioned program.

When the engine key 21 is turned on and the program starts, step S3 is started.
In 1, it is determined whether EC is currently in the filter regeneration suspended state or not.
Reading from U12 of B-RAM 12f, for example, it determines one of the flags F ₁ to F ₅ described above (corresponds to the period of FIG. 4) is in whether or not it is set to 1. Then, in the case of No in the present step S31, since the filter regeneration is not suspended, the following steps are skipped and the present program is terminated (restart of the particulate collection mode).

On the other hand, if Yes in step S31, the routine proceeds to step S32, where the value of the timer T started in step S24, that is, the elapsed time from stop to restart is read, Further, in step S33, the current filter temperature tf is detected, and in subsequent step S34, filter regeneration according to the time T and the magnitude of the temperature tf in each of the filter regeneration periods previously interrupted,
Alternatively, particulates and a collection process are performed.

Hereinafter, the specific processing contents of step S34 will be described in order from period to period of FIG. FIG. 7 shows a process executed at restart when the interrupted reproduction is for a period. First, in step S341, it is countered whether the elapsed time T is within a predetermined time Ta (for example, 1 minute). If Yes in this step S341, since there is no problem in continuing the regeneration as it is because the operation stop time is short, the process proceeds to step S342, and the regeneration control is restarted from the interrupted state. In this case, the routine of FIG. 5 also starts to operate.

On the other hand, if No is determined in step S341, it is determined that the time elapsed from the stop of operation is long, and the process proceeds to step S343, where the flag F ₁ is reset and the interrupted regeneration process is performed. Return to a blank sheet, then proceed to step S344, where the read engine speed N,
From the water temperature Thw and the filter temperature tf, the regeneration start condition in which the current engine state is predetermined (for example, N ≠ 0; Thw
≧ 65 ° C .; tf ≧ 150 ° C.) is determined, and if satisfied (Yes), step S
At 345, reproduction is started from the first filter 2. In addition, when it is determined No in step S344, the reproduction is waited until the reproduction start condition is satisfied.
The device may be temporarily returned to the particulate collection mode.

Next, FIG. 8 shows that when the interrupted regeneration is the heater energization period of the first filter 2, that is, when the flag F ₂ = 1
This is a process executed at the time of restart, and first, step S35.
At 1, it is determined whether the elapsed time T is within a predetermined period Ta (for example, 1 minute). Then, in the present step S351, Yes
In the case of, the routine proceeds to step S352, and it is determined whether or not the current filter temperature tf detected in the previous step S33 is much lower than the filter temperature Ts at the time of the regeneration interruption (for example, tf > Tfa-10
0 ℃? ), If Yes in this step S352, the routine proceeds to step S353 to restart the reproduction control from the suspended state. In this case, it is preferable that the heater energization time be the remaining time obtained by subtracting the actual energization time from the preset heater energization time and the elapsed time T added (at the same time, the routine of FIG. 5 is started). ..

On the other hand, step S351 and step
If No in S352, the filter temperature is low.
It is determined that the degree of lowering is large, and the process proceeds to step S354
Gu F ₂To reset the playback process to a blank page.
Return, and then proceed to step S355, where the previous period is
Engine speed N and water temperature Th read in the same way
w, the filter temperature tf, the current engine state
It is judged whether the start condition is satisfied, and the condition is satisfied.
If yes (Yes), the first filter is selected in step S356.
Playback starts from 2. Incidentally, in step S355, No
If so, wait for playback.

In the restart process for the regeneration interruption in the above-mentioned period, the filter temperature tf at the time of the restart is also used as the regeneration control parameter in addition to the interruption time T from the engine stop to the restart. If the temperature in the vicinity of the heater is low, the possibility that particulate ignition cannot occur even if the interruption time t is short cannot be said to be zero. Therefore, it is an attempt to avoid defective regeneration due to such a cause. Since there is a close relationship with the interruption time, as another embodiment, step S352 in FIG.
You may make it depend only on the judgment of the interruption time T simply.

Next, reproduction is suspended for a period (flag F ₃ = 1)
The restart-time processing in the case of will be described. As described in steps S24 and S25 of the flowchart of FIG.
_{In the} state in which ₃ is set to 1, since the regeneration of the first filter 2 is completed, the regeneration shifts to the second step 3 regardless of the magnitude of the regeneration interruption time T when restarting. Preferably.

Therefore, in this embodiment, the condition for starting the filter regeneration after the restart (for example, N ≠ 0; Thw ≧ 65)
C .; tf.gtoreq.150.degree. C.), the regeneration of the remaining second filter 3 is started, and the routine of FIG. 5 is also started along with the resumption of the regeneration. Regarding the reproduction interruption during the period, the situation is exactly the same as in the case of the period in the first filter 2. That is, in the present embodiment, in the case of the pre-processing interruption of the second filter 3, each processing corresponding to the interruption time t is executed, which is exactly the same as the processing described in FIG. 7, except that step S343 is different. It is only that the flag F ₄ is reset to 0 and the reproduction is restarted from the preprocessing of the second filter 3 in step S345.

Similarly, regarding the period as well,
The content exactly matches the case of the period described in FIG. Immediately
If the heater energization of the second filter 3 is interrupted, restart
Is dependent on the interruption time T and the filter temperature tf at that time.
The heater energization is restarted only after both conditions are cleared.
Otherwise, the flag F corresponding to step S354
_FiveHas been reset and the above playback start conditions have been met.
In this case, the regeneration process of the second filter 3 from the period is started.
Will be done.

As described above, the filter regeneration interruption state is subdivided,
In each of them, an example in which the content of the regeneration process after the restart is changed according to the length of the interruption time has been described, but according to this example, the filter temperature is further set as the resumption parameter of the regeneration interruption while the heater is energized. By taking into consideration, the filter state at the time of restart can be detected more clearly, the regeneration can be ensured without wasting the heat amount, and the regeneration failure can be prevented.

Further, each of the above-mentioned embodiments is a dual-flow exhaust gas purifying apparatus of the forward flow regeneration system in which two filters 2 and 3 are arranged in parallel in the exhaust passage, but the concept of the present invention is not limited to this embodiment. Of course, it can be applied to an exhaust gas purification device with only a single filter that is not arranged in parallel, and it can also be applied to a backflow regeneration type exhaust gas purification device that supplies regeneration gas from the filter downstream side during filter regeneration. Can also be applied.

[0063]

As described above, according to the present invention, when the engine operation is stopped during the filter regeneration, the regeneration after the restart is performed when the elapsed time from the stop to the restart is shorter than the predetermined time. Since it is carried out and is re-collected without being regenerated when it is long, the amount of heat generated by the regenerative heating means is less than that of the conventional device which regenerates after restarting regardless of the elapsed time.

Further, in the apparatus according to the second aspect, when the elapsed time from the stop of the engine during regeneration to the restart is short and the filter temperature at the restart after the stop of the engine during regeneration is equal to or higher than a predetermined temperature. , Regeneration is performed at the time of restart, it is possible to surely reproduce without wasting heat amount, and when the temperature is lower than the predetermined temperature, by re-collecting, even if the time until restart is short, If the filter temperature is equal to or lower than the predetermined temperature, the regeneration can be prohibited and the regeneration failure can be prevented.

On the other hand, as the elapsed time is shorter, the heating amount of the regeneration heating means is reduced, so that the amount of heat is less wasted, and therefore efficient regeneration can be carried out.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exhaust emission control device as an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the ECU of FIG. 1 when the engine operation is stopped during filter regeneration.

FIG. 3 is a flow chart diagram illustrating a program executed when the engine is restarted regarding the operation of the ECU of FIG. 1.

FIG. 4 is a specific time chart diagram in a filter regeneration process of the exhaust emission control device shown in FIG.

FIG. 5 is a flowchart similar to FIG. 2, illustrating an ECU operation according to a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating a program executed when the engine is restarted with respect to the ECU operation described in FIG.

FIG. 7 is a flowchart showing specific processing content following step S33 of FIG. 6 and dealing with reproduction interruption during the period of FIG. 4;

FIG. 8 is a flowchart diagram, similar to FIG. 7, for coping with reproduction interruption during the period of FIG.

[Explanation of symbols]

 2, 3 ... Filter 9, 10 ... Electric heater (regeneration heating means) 12 ... Control circuit (ECU) 12c ... CPU 12g ... Timer clock

Claims (3)

[Claims] 1. Exhaust gas purification having a filter provided in an exhaust system of a diesel engine for collecting particulates in exhaust gas, and regeneration heating means for heating the filter to ignite and burn the particulates when the filter is regenerated. In the device, further, means for detecting the passage of time from the time the engine is stopped during engine regeneration to the time of engine restart, and if the elapsed time is shorter than a predetermined time, while continuing filter regeneration after restart, An exhaust emission control device comprising: filter operation control means for collecting particulates again after restart when the elapsed time is longer than a predetermined time. 2. A means for detecting the temperature of the filter, wherein the filter operation control means continues the filter regeneration when the elapsed time is short and the filter temperature at the time of engine restart is equal to or higher than a predetermined temperature. The exhaust gas purification device according to claim 1, wherein particulates are collected when the temperature is equal to or lower than a temperature. 3. Exhaust gas purification comprising a filter provided in an exhaust system of a diesel engine for collecting particulates in exhaust gas, and regeneration heating means for heating the filter to ignite and burn the particulates during regeneration of the filter. In the apparatus, further, the means for detecting the time elapsed from the time when the engine is stopped during the filter regeneration to the time when the engine is restarted, and the shorter the detected elapsed time, the more the heating amount of the regeneration heating means after the restart. An exhaust gas purification device, characterized by being provided with a regeneration heating control means for reducing.