JP2989954B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, and more particularly, to regeneration of a filter in an apparatus for collecting and removing particulates contained in exhaust gas of a diesel engine by a filter provided in an exhaust passage. The present invention relates to an exhaust gas purifying apparatus capable of performing the above-described method irrespective of the residual amount of particulates in the filter after regeneration of the filter.

[0002]

2. Description of the Related Art Exhaust gas from an internal combustion engine such as an automobile, particularly a diesel engine contains exhaust particulates mainly composed of carbon, which causes black smoke. From the viewpoint of environmental pollution, it is desirable to remove the particulates. In recent years, it has been proposed to dispose a ceramic filter in an exhaust passage of a diesel engine and remove the diesel particulates with the filter.

FIG. 10 shows a conventional exhaust gas purifying apparatus 1 for an internal combustion engine.
0 shows a general configuration of a conventional exhaust gas purifying apparatus 10 of a reverse flow type, in which a regeneration gas flows from a direction opposite to a direction in which exhaust gas flows to regenerate a filter for collecting particulates. It is shown. In the figure, 1 is a diesel engine, 2 is an exhaust gas passage, 3 is a casing for storing a filter provided in a part of the exhaust gas passage 2, 4
Is a sealing material, 5 is a particulate filter for collecting particulates in exhaust gas contained in the casing 3, 6 is a secondary air supply passage, 7 is a combustion gas discharge passage, and 8 is a particulate filter 5. An exhaust bypass passage for bypassing, an air pump 9 for supplying secondary air,
H is an electric heater, V1 is a switching valve for switching between the exhaust passage 2 and the exhaust bypass passage 8, V2 is an outlet switching valve provided at the outlet of the exhaust bypass passage 8, V3 is an on-off valve for the combustion gas discharge passage 7, and V4 is 3 shows an on-off valve of a secondary air supply passage 6.

In the exhaust gas purifying apparatus 10 configured as described above, at the time of collecting particulates in normal exhaust gas,
Each of the valves V1 to V4 is located at a position indicated by a broken line, and the diesel engine 1
The exhaust gas discharged from is removed by the particulate filter 5 and released into the atmosphere via a muffler (not shown). On the other hand, when the amount of particulates collected inside the particulate filter 5 increases with the use of the particulate filter 5, the air permeability gradually decreases,
Engine performance will be reduced. Therefore, when the pressure difference between the pressure of the exhaust gas on the upstream side of the particulate filter 5 and the pressure on the downstream side becomes larger than a predetermined value, the pressure sensor detects the difference, and the particulate regeneration processing is performed. During this regeneration process, each of the valves V1 to V4 switches to the position indicated by the solid line. In this state, the exhaust gas from the diesel engine 1 is discharged into the air through the exhaust bypass passage 8. At this time, the heater H is energized, and secondary air is supplied from the air pump 9 to burn the particulates collected by the particulate filter 5. Then, the combustion gas is released from the combustion gas discharge passage 7 into the air.

However, in the exhaust gas purification apparatus 10 configured as described above, if there is unburned particulate matter in the particulate filter 5 after the regeneration process, the next trapping amount is affected by the unburned particulate matter, and Even if the same regeneration process is performed as in the state where there is no residue, unburned residue will remain forever, and there is a possibility that good collection cannot be performed.

Therefore, by measuring the temperature on the downstream side of the particulate filter 5 at the time of the regeneration processing, the remaining unburned portion is determined, and after the remaining unburned portion, the amount of trapped particulate in the next time is increased to reduce the unburned portion. It has been proposed to eliminate it (Japanese Patent Laid-Open No. Hei 3-18614).

[0007]

However, as described in Japanese Patent Application Laid-Open No. Hei 3-18614, when there is unburned particulate matter, simply increasing the amount of collected particulate matter at the next time increases the amount of unburned part. The trapping amount is increased, and the temperature of the part becomes high during the burning of the particulates, which may cause deterioration (melting damage or cracks) of the particulate filter.

Therefore, the present invention solves the above-mentioned problems of the conventional exhaust gas purifying apparatus for an internal combustion engine, and when the unburned portion remains after the regeneration of the particulate filter, the particulate filter deteriorates at the next regeneration process. It is an object of the present invention to provide an exhaust gas purifying apparatus for an internal combustion engine that can eliminate unburned fuel without causing the generation.

[0009]

According to a first aspect of the present invention, there is provided a device for purifying exhaust gas of an internal combustion engine, which traps particulates in the exhaust gas by a filter provided in an exhaust gas passage of the internal combustion engine. Collected, heated by the heating means to ignite the particulates, and at the same time, the regeneration gas is supplied by the regeneration gas supply means, and the exhaust gas is burned to regenerate the filter. A particulate remaining amount detecting means for detecting an unburned amount of particulates, and a heating means control means for reducing a heating amount of the heating means as the unburned amount near the heating means increases. I have.

In a second embodiment of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the particulates in the exhaust gas are collected by a filter provided in an exhaust gas passage of the internal combustion engine and heated. Means for heating the particulates to ignite the particulates, and at the same time, supplying the regeneration gas by the regeneration gas supply means and burning the same to regenerate the filter. Particulate remaining amount detecting means for detecting whether or not there is a residue; and regeneration gas supply means for reducing the amount of regeneration gas supplied from the regeneration gas supply means in the latter half of regeneration when particulates remain unburned. And control means are provided.

[0011]

According to the exhaust gas purifying apparatus for an internal combustion engine according to the first aspect of the present invention, the amount of unburned particulates in the particulate filter is detected, and the larger the amount of unburned fuel near the heating means, the more the heating means becomes. Control for reducing the heating amount is performed. Further, according to the exhaust gas purifying apparatus for an internal combustion engine of the second embodiment of the present invention, the amount of unburned particulates in the filter is detected. Is performed to reduce the supply amount of the regeneration gas. As a result, when collecting and performing a regeneration process after the occurrence of unburned residue, the particulate filter is less likely to deteriorate.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an exhaust gas purifying apparatus 20 for an internal combustion engine according to one embodiment of the present invention equipped with an electric heater H and having a particulate filter 5 for trapping particulates in exhaust gas. The same components as those of the conventional exhaust gas purifying apparatus 10 for an internal combustion engine shown in FIG. Therefore, in FIG.
3 is a casing for accommodating a particulate filter 5 provided in a part of the exhaust gas passage 2, 4 is a sealing material, 6 is a secondary air supply passage, 7 is a combustion gas discharge passage, 8
Is an exhaust bypass passage that bypasses the particulate filter 5, 9 is an electric air pump that supplies secondary air,
1 is a switching valve for switching between the exhaust passage 2 and the exhaust bypass passage 8, V2 is an outlet switching valve provided at the outlet of the exhaust bypass passage 8, V3 is an on-off valve for the combustion gas discharge passage 7, and V4 is a secondary air supply passage. 6 shows the on-off valve 6. The components newly added to FIG. 1 are a battery 11, a control circuit 10
0, a heater switch S for controlling energization to the electric heater H, a pressure sensor SP1 provided in the passage 2 on the exhaust gas inflow side of the particulate filter 5, and a passage in the passage 2 on the exhaust gas outflow side of the particulate filter 5. Is a pressure sensor SP2 provided in the.

The particulate filter 5 is a honeycomb filter having a honeycomb-shaped partition wall made of a porous material. The particulate filter 5 is generally cylindrical and has a large number of rectangular parallelepiped passages surrounded by partition walls. The adjacent passage is alternately plugged with a closing member made of ceramic on the exhaust gas inflow side and the exhaust gas outflow side to form a closed passage.

The control circuit 100 includes, for example, an interface INa for inputting an analog signal, an interface INd for inputting a digital signal, a converter A / D for converting an analog signal into a digital signal, a central processing unit CPU for performing various arithmetic processing, a random processing unit CPU, The microcomputer includes a microcomputer including an access memory RAM, a read-only memory ROM, an output circuit OUT, and a bus line 111 for connecting them, but a detailed description of the configuration is omitted. The interface INa for inputting an analog signal of the control circuit 100 includes pressure detection signals from pressure sensors SP1 and SP2 for detecting the pressure of exhaust gas on the upstream and downstream sides of the exhaust gas path of the particulate filter 5, and rotation (not shown). An engine speed signal Ne or the like from a number sensor is input, and a signal from a key switch or the like is input to a digital signal input interface INd.

At the time of collecting particulates in the normal exhaust gas, the valves V1 to V4 are controlled to the positions indicated by broken lines, and the exhaust gas discharged from the diesel engine 1 is supplied to the particulate filter built in the casing 3. The particulates are removed by 5 and released into the atmosphere via a muffler (not shown). On the other hand, the pressure on the exhaust gas inflow side (upstream side) of the particulate filter 5 becomes larger than the pressure on the exhaust gas outflow side (downstream side) beyond a predetermined value, and the differential pressure becomes higher than the predetermined value. Pressure sensor SP
1, when detected by SP2, the valves V1 to V4 are switched from the broken line position to the solid line position by the control circuit 100, and the regeneration operation of the particulate filter 5 is performed. When the particulate filter 5 is switched to the regenerating operation, the control circuit 100 performs on / off control of the heater switch S and control of the flow rate of the secondary air from the electric air pump 9 together.

FIG. 2 is a routine showing the control by the control circuit 100 during the reproduction of the particulate filter 5.
It is executed every predetermined time. In step 201, first, the differential pressure ΔP on the upstream and downstream sides of the particulate filter 5 is detected from the pressure values detected by the sensors SP1 and SP2. The next step 202 is to determine whether or not this time is immediately after the start of collection after the end of the regeneration. If it is determined that this time is immediately after the start of collection (YES), the process proceeds to step 203 and the collection time Tc
Is cleared and the differential pressure ΔP detected in step 201 is set as the initial differential pressure ΔPi, and the routine proceeds to step 205. On the other hand, if it is determined that this time is not immediately after the start of collection (NO), the collection time Tc is counted in step 204, and then the flow proceeds to step 205.

In step 205, it is determined whether or not the pressure difference ΔP detected in step 201 has reached the regeneration reference value ΔPc. If the differential pressure ΔP is equal to or less than the regeneration reference value ΔPc (NO), the routine proceeds to step 225 to end this routine, and if the differential pressure ΔP exceeds the regeneration reference value ΔPc, the routine proceeds to step 206 and thereafter, where the particulate filter 5 Reproduction processing is performed.

In step 206, counting of the reproduction time Tr is started, and in steps 208 to 212, the present reproduction mode is determined. First, at step 207, it is determined whether or not the previous reproduction time Tro is shorter than a predetermined time Ta. The predetermined time Ta in step 207 determines whether or not the particulate filter 5 has ignited during the previous regeneration. If the previous regeneration time Tro is shorter than the predetermined time Ta, the particulate filter is ignited during the previous regeneration. It is determined that it has not been done. This predetermined time Ta is:
For example, it is set to a value that is half of the energizing time to the heater H. Therefore, this determination is to determine that the previous playback mode has not been executed due to interruption of playback or the like. If the playback mode has been completed in an extremely short time, the same playback mode as the previous playback mode is repeated by step 208 or step 209. That's what we do.

In the processing in reproduction mode C in step 216 to be described later, the reproduction flag SFC becomes "1" at the time of this processing, and in the processing in reproduction mode B in step 219, the reproduction flag SFB becomes "1" in this processing. It has become. Therefore, when the answer is YES in step 207, it is determined in step 208 whether or not the last time was the reproduction mode B, and whether or not the last time was the reproduction mode C in step 209.
Checked by SFB and flag SFC, YE at step 208
In the case of S, the reproduction is performed in the reproduction mode B in Step 219. In the case of YES in Step 209, the reproduction is performed in the reproduction mode C. In the case of NO in Steps 208 and 209, the reproduction is performed in the reproduction mode A. The process proceeds to step 213.

On the other hand, in step 210, which proceeds when the determination in step 207 is NO, a flag SFB indicating the previous reproduction mode is set.
And the flag SFC are cleared. In the following step 211, it is determined whether or not the initial differential pressure ΔPi immediately after the start of collection obtained in step 203 is equal to or more than a predetermined value K.
The current collection time Tc counted in 204 is a predetermined time L
It is determined whether or not this is the case. The predetermined value K in step 211 is for determining the unburned amount, and the initial differential pressure ΔP
When i is equal to or larger than the predetermined value K, it is determined that the unburned amount at the time of the previous reproduction is large. The predetermined time L in step 212 is used to determine the magnitude of the particulate collection amount at the time of the current collection.

Then, according to the distribution of steps 207 to 212, the current reproduction processing mode is changed to steps 213 and 213.
The reproduction mode is determined to be any of the three types of reproduction mode A to reproduction mode C shown in steps 216 and 219. Each of the reproduction modes A to C will be described in detail with reference to FIG. 3, but the reproduction processing in each mode is as follows. (1) Regeneration mode A This is a normal regeneration mode in which the previous regeneration processing was performed normally or the regeneration processing was not executed in the previous regeneration mode A. Also, the reproduction process is performed normally.

Therefore, the reproduction process is performed in the reproduction mode A when the previous reproduction time Tro is determined to be shorter than the predetermined time Ta in step 207, and when both are NO in steps 208 and 209. In step 207, it is determined that the previous reproduction time Tro is longer than the predetermined time Ta,
This is the case where it is determined in Step 1 that the initial differential pressure ΔPi is smaller than the predetermined value K, and that the current collection time Tc is longer than the predetermined time L in Step 212.

If the reproduction process in the reproduction mode A is being executed in step 213, step 214
In step 215, it is determined whether the regeneration has been interrupted due to an engine stop or the like. In step 215, it is determined whether the regeneration has been completed. If it is determined in step 214 that the reproduction has been interrupted, the process proceeds to step 222, where the reproduction time Tr until the interruption is stored as the previous reproduction time Tro, and in step 224, the reproduction time Tr is cleared.
The routine ends at 225. Also step
If it is determined at 214 that the reproduction has not been interrupted and it is determined at step 215 that the reproduction has not been completed, the process returns to step 213 to continue the reproduction process.If it is determined at step 215 that the reproduction process has been completed, At step 223, a time longer than the above-mentioned predetermined time Ta, for example, Ta + α (α> 0) is stored as the previous reproduction time Tro. At step 224, the reproduction time Tr is cleared, and at step 225, this routine ends. (2) Regeneration mode B This is a regeneration mode in which particulates remain in the vicinity of the heater of the particulate filter in the previous regeneration process, in which the amount of electricity supplied to the heater is reduced and the amount of regeneration gas is also reduced. Is performed.

Therefore, the reason why the reproduction process is performed in the reproduction mode B is that the previous reproduction time Tro is determined to be shorter than the predetermined time Ta in step 207, and YES in step 208.
And the case where it is determined in step 207 that the previous reproduction time Tro is longer than the predetermined time Ta, and in step 211 it is determined that the initial differential pressure ΔPi is larger than the predetermined value K.

If the reproduction process in the reproduction mode B is being executed in step 219, the reproduction flag SF
B is set to "1", and it is determined in step 220 whether or not regeneration has been interrupted due to an engine stop or the like.
It is determined whether or not the reproduction has been completed. If it is determined in step 220 that playback has been interrupted, step 22
Then, the reproduction time Tr until interruption is stored as the previous reproduction time Tro, the reproduction time Tr is cleared in step 224, and this routine is terminated in step 225. If it is determined in step 221 that the reproduction has not been interrupted and that the reproduction has not been completed in step 221, the process returns to step 219 to continue the reproduction process, and in step 221 it is determined that the reproduction process has been completed. Then, at step 223, a time longer than the above-mentioned predetermined time Ta, for example, Ta + α (α> 0) is stored as the previous reproduction time Tro, the reproduction time Tr is cleared at step 224, and this routine is terminated at step 225. I do. (3) Reproduction mode C This is a reproduction mode in which the particulates remain uniformly on the part of the particulate filter farther from the heater in the previous reproduction processing. The regeneration process is performed with the gas amount reduced.

Therefore, the reason why the reproduction process is performed in the reproduction mode C is that the previous reproduction time Tro is determined to be shorter than the predetermined time Ta in step 207, and NO in step 208,
If YES in step 209, it is determined in step 207 that the previous reproduction time Tro is longer than the predetermined time Ta, and it is determined in step 211 that the initial differential pressure ΔPi is smaller than the predetermined value K. This is the collection time T at 212
This is the case where it is determined that c is shorter than the predetermined time L.

When the reproduction process in the reproduction mode C is being executed in step 216, the reproduction flag SF
C is set to "1", and it is determined in step 217 whether or not regeneration has been interrupted due to an engine stop or the like.
It is determined whether or not the reproduction has been completed. If it is determined in step 217 that the reproduction has been interrupted, step 22
Then, the reproduction time Tr until interruption is stored as the previous reproduction time Tro, the reproduction time Tr is cleared in step 224, and this routine is terminated in step 225. If it is determined in step 217 that the reproduction has not been interrupted and that the reproduction has not been completed in step 218, the process returns to step 216 to continue the reproduction process, and in step 218 it is determined that the reproduction process has been completed. Then, at step 223, a time longer than the above-mentioned predetermined time Ta, for example, Ta + α (α> 0) is stored as the previous reproduction time Tro, the reproduction time Tr is cleared at step 224, and this routine is terminated at step 225. I do.

FIG. 3 shows the supply amount of the secondary air from the air pump 9 and the heater H in the regeneration modes A to C described above.
This shows the state of energization to. In the normal regeneration mode A, the secondary air from the air pump 9 flows at a rate of 10
The heater H is supplied with 0 liter and the heater H is energized for a time tA. In the regeneration mode B, the secondary air from the air pump 9 is initially supplied at 100 liters per minute, and thereafter, the secondary air from the air pump 9 is supplied at 50 liters per minute until the time exceeds 20 minutes. . The heater H is energized for a time shorter than the time tA. Further, in the regeneration mode C, the secondary air from the air pump 9 is initially supplied at a rate of 100 liters per minute longer than in the regeneration mode B, and thereafter, the secondary air from the air pump 9 is supplied until more than 20 minutes. Supplied at 50 liters per minute. The heater H is energized for a time longer than the time tA.

With the above control, in the reproduction mode B, the particulates remaining around the particulate filter and the particulates remaining near the heater in the previous reproduction processing are reproduced without deterioration of the particulate filter. You. Further, in the reproduction mode C, the particulates uniformly remaining on the part of the particulate filter farther from the heater in the previous reproduction processing are reproduced without deterioration of the particulate filter.

FIG. 4 is a routine showing another control during reproduction of the particulate filter 5 by the control circuit 100. This is a processing in which another reproduction mode is added to the reproduction processing described in FIG. Is shown. This routine is also executed at predetermined time intervals. In the reproduction processing shown in FIG. 4, when the reproduction mode C in the processing of FIG. 2 is continuously processed a predetermined number of times, the processing is performed in another reproduction mode D to reliably reduce the possibility that the particulates will remain unburned. I am trying to do it.

The regeneration process in the regeneration mode D is for regenerating and removing particulates that may remain in the continuous regeneration process in the regeneration mode C. The heater energization amount is increased as much as possible, and the regeneration gas amount is reduced. The reproduction process is performed by supplying a small amount and a long time.
In the routine shown in FIG. 4, a step 402 is provided after the step 218, and the number N of times that the reproduction processing in the reproduction mode C is continuously executed is counted. Then, step 401 is provided before step 216 to determine whether or not the number N of continuous executions of the reproduction process in the reproduction mode C exceeds a predetermined number M, and the reproduction process in the reproduction mode C is executed M times in succession. Thereafter, the process proceeds to step 403, where the reproduction process is performed in the reproduction mode D. This playback mode D
Then, the reproduction flag SFC is set to "1". Then, in step 404, it is determined whether or not the reproduction is interrupted. When the reproduction is interrupted, the process proceeds to step 222 so that the next reproduction in the reproduction mode C is performed. If NO in step 404, it is determined in step 405 whether or not the reproduction is completed. If the reproduction is not completed, the process returns to step 403. If the reproduction is completed, the process proceeds to step 406, and the reproduction in the reproduction mode C is performed. The number N of consecutive executions of the process is cleared. Further, when the reproduction process in the reproduction mode A and the reproduction mode B in the steps 213 and 219 is executed in the middle of the reproduction mode C, the process proceeds to the step 406 before proceeding to the step 223, and the number N of continuous reproductions in the reproduction mode C is reduced. I try to be cleared.

In the above-described embodiment, the supply amount of the secondary air is adjusted according to the rotation of the air pump 9, but the supply amount of the secondary air may be increased or decreased other than the rotation of the air pump 9. Can be. An example is shown in FIG. FIG.
3A shows an example in which a branch passage 60 is provided in the secondary air supply passage 6 from the air pump 9, and an oxygen-enriched film 90 is provided in the branch passage 60. A switching valve V5 is provided at the entrance of the branch passage 60, and an air filter 9f is provided at the air intake of the air pump 9. Oxygen-enriched membrane 9
Numeral 0 indicates that the intake air has a high oxygen concentration and is released. The secondary air passing through the branch passage 60 has a high oxygen concentration, which is equivalent to supplying a large amount of secondary air. Therefore, the supply amount of the secondary air can be increased without increasing the supply capacity of the air pump 9. Further, by adjusting the position of the switching valve V5, the opening area of the secondary air supply passage 6 and the branch passage 60 is changed so that ordinary secondary air and secondary air having a high oxygen concentration are mixed. The degree of increase of the secondary air can be changed.

FIG. 5 (b) shows another air pump 91 provided in parallel with the air pump 9 and a nitrogen / oxygen separator 50 provided on the secondary air discharge side of the air pump 91 to separate the separated oxygen and nitrogen independently. This is an example of merging with the secondary air supply passage 6. The nitrogen and oxygen separator 50 uses a molecular sieve membrane (oxygen-enriched membrane) capable of separating nitrogen and oxygen,
This can be achieved by using an adsorbent that separates nitrogen and oxygen. Since nitrogen and oxygen can be separately taken out from the nitrogen and oxygen separator 50, an on-off valve VN2 is provided on the nitrogen discharge port side and an on-off valve VO2 is provided on the oxygen discharge port side, and both are independently provided. It is possible to join the secondary air supply passage 6. And if the amount of nitrogen from the separator 50 is increased, the amount of nitrogen in the secondary air is increased,
If the oxygen concentration is lowered and this is equivalent to a reduction in the secondary air, conversely if the amount of oxygen from the separator 50 is increased,
(4) The oxygen concentration in the air is increased, which is equivalent to supplying a large amount of secondary air. Therefore, the supply amount of the secondary air can be increased without increasing the supply capacity of the air pump 9. Also, by adjusting the positions of the on-off valves VN2 and VO2,
By changing the ratio of nitrogen and oxygen discharged from the separator 50, the degree of increase in the amount of secondary air can be changed.

The embodiment described above is an example of an exhaust gas purifying apparatus for an internal combustion engine in which one particulate filter 5 is provided in the exhaust passage of the internal combustion engine. The present invention relates to an internal combustion engine as shown in FIG. The present invention can also be applied to an exhaust gas purifying apparatus 30 for a dual filter type internal combustion engine in which two particulate filters 51 and 52 are provided by branching the exhaust passage.
The exhaust gas purifying apparatus 30 of the internal combustion engine shown in FIG. 6 includes heaters H1 and H1 provided on the end faces of the particulate filters 51 and 52.
This is a type in which side heaters H3 and H4 are provided on the outer periphery in addition to H2, but the other components are the same as those in the embodiment of FIG. 2 except for the particulate filters 51 and 52. The description is omitted by attaching the reference numerals,
Only different parts will be described.

In the exhaust purification apparatus 30 for a dual type internal combustion engine, the exhaust passage 2 is divided into branch passages 21 and 22, and switching valves V11 and V21 are provided at the branch points, respectively. Further, in the middle of the branch passages 21 and 22,
Particulate filters 51, 52 housed in casings 31, 32, and secondary air supply passages 61, 62
And combustion gas discharge passages 71 and 72, and open / close valves V41, V42, V31 and V32 are provided in the respective passages.

During normal collection of particulates in exhaust gas, the valves V11, V21, V31 and V41 are controlled to the positions indicated by solid lines, and the exhaust gas discharged from the diesel engine 1 is supplied to both particulate filters. 51,
The particulates are removed by 52 and released into the atmosphere via a muffler (not shown). On the other hand, when the pressure on the upstream side of the valve V11 becomes larger than the pressure on the downstream side of the valve V21 by more than a predetermined value, and the pressure sensors SP1 and SP2 detect that the differential pressure has become equal to or more than the predetermined value, Reproduction of the particulate filters 51 and 52 is performed alternately. That is, first, the control circuit 100 controls the valves V11 and V2.
1 closes the branch passage 22 side, the valves V31 and V41 open, and the secondary air from the air pump 9 is supplied to the secondary air supply passage 6
1 and the heaters H1 and H3 are energized to discharge the combustion gas from the combustion gas discharge passage 71.

FIG. 7 is a routine showing the control performed by the control circuit 100 during the reproduction of the particulate filters 51 and 52 of FIG. 6, and is executed at predetermined time intervals. Step 701
First, based on the pressure values detected by the sensors SP1 and SP2, upstream of the particulate filters 51 and 52,
The downstream differential pressure ΔP is detected. In the following step 702, the differential pressure ΔP detected in step 801 is reduced to the regeneration reference value ΔP
It is determined whether or not c has been reached. If the differential pressure ΔP is equal to or less than the regeneration reference value ΔPc (NO), the routine proceeds to step 705 to end this routine, and if the differential pressure ΔP exceeds the regeneration reference value ΔPc, the routine proceeds to step 703 and thereafter to proceed to the first particulate filter. When the reproduction process of the second particulate filter 52 is completed, the reproduction process of the second particulate filter 52 is performed in step 704, and the routine ends.

FIG. 8 shows each particulate filter 51,
52 shows an example of the procedure of the playback process of No. 52. In step 801, the counting of the reproduction time Tr is started.
From 2 to step 804, the current reproduction mode is determined. That is, in step 802, it is determined whether or not the previous reproduction time Tro is smaller than the predetermined time T1, and in step 803, it is determined whether or not the previous reproduction time Tro is smaller than the predetermined time T2. In, it is determined whether or not the previous reproduction time Tro is shorter than a predetermined time T3. The predetermined time T1 to T3 is set to a side heater H3 described later.
This is a time indicating halfway of the energization time to H4. In this embodiment, the side heaters H3 and H4 are initially energized with a large amount of power, and thereafter energized with a small amount of power for a predetermined time. Then, during energization with this small amount of power, energization to the end face heaters H1 and H2 is performed. T1, for example, as shown in FIG. 9, is the time from the start of energization to the side heaters H3, H4 with a large amount of power to the energization with a small amount of power, and T2 is the period from the start of energization to the side heaters H3, H4. T3 is a time from the start to the end of energization to the side heaters H3 and H4 until a predetermined time after the start of energization to the end face heaters H1 and H2.

Then, according to the distribution of steps 802 to 804, the current reproduction processing mode is changed to steps 805 and 804.
It is determined from the first reproduction mode shown in steps 808 and 811 to one of the three types of the third reproduction mode. The reproduction process in each mode is as follows. (1) First regeneration mode This is a regeneration mode in which the previous energization to the side heater was normally performed or the previous energization to the side heater was interrupted when the amount of power was large, and is shown in FIG. As described above, the regeneration process is performed with the end face heater power supply amount being normal.

Therefore, the reproduction process is performed in the first reproduction mode when it is determined in step 802 that the previous reproduction time Tro is shorter than the predetermined time T1,
This is a case where it is determined in 804 that the previous reproduction time Tro is longer than the predetermined time T3. When the reproduction process in the first reproduction mode is being executed in step 805,
At step 806, it is determined whether or not the regeneration has been interrupted due to an engine stop or the like. At step 807, it is determined whether or not the regeneration has been completed. If it is determined in step 806 that the reproduction has been interrupted, the process proceeds to step 814, where the reproduction time Tr until the interruption is stored as the previous reproduction time Tro, and the reproduction time Tr is cleared. To end. If it is determined in step 806 that the reproduction has not been interrupted and that the reproduction has not ended in step 807, the process returns to step 805 to continue the reproduction process, and in step 807 it is determined that the reproduction process has ended. Then, in step 814, the reproduction time Tr is stored as the previous reproduction time Tro, the reproduction time Tr is cleared, and in step 815, this routine ends. (2) Second regeneration mode This is a regeneration mode in the case where interruption is performed during energization of the side heater with low power in the previous regeneration process, and as shown in FIG. The reproduction process is performed with the volume reduced from the normal time.

Accordingly, the reproduction process is performed in the second reproduction mode when the previous reproduction time Tro is longer than the predetermined time T1 but shorter than the predetermined time T2 in steps 802 and 803. is there. Again step
When the reproduction process in the second reproduction mode is being executed in 808, it is determined in step 809 whether or not the reproduction has been interrupted due to an engine stop or the like, and in step 810, it is determined whether or not the reproduction has ended. If it is determined in step 809 that the reproduction has been interrupted, the process proceeds to step 814, where the reproduction time Tr until the interruption is stored as the previous reproduction time Tro, and the reproduction time Tr is cleared. To end. If it is determined in step 809 that the reproduction has not been interrupted and that the reproduction has not ended in step 810, the process returns to step 808 to continue the reproduction process, and in step 810, it is determined that the reproduction process has ended. Then, in step 814, the reproduction time Tr is stored as the previous reproduction time Tro, and the reproduction time Tr is stored.
Is cleared, and this routine ends in step 815. (3) Third regeneration mode This is a regeneration mode in the case where power is being supplied to the side heater with low power in the previous regeneration process and interruption has been performed after the power supply to the end face heater has been started, as shown in FIG. The regeneration process is performed with the end-face heater energization amount made larger than usual.

Accordingly, the reproduction process is performed in the second reproduction mode when it is determined in steps 802 to 804 that the previous reproduction time Tro is longer than the predetermined time T2 but shorter than the predetermined time T3. is there. Again step
When the regeneration process in the second regeneration mode is being executed in 811, it is determined in step 812 whether or not the regeneration has been interrupted due to an engine stop or the like, and in step 813, it is determined whether or not the regeneration has ended. If it is determined in step 812 that the reproduction has been interrupted, the process proceeds to step 814, where the reproduction time Tr until the interruption is stored as the previous reproduction time Tro, and the reproduction time Tr is cleared. To end. If it is determined in step 812 that the reproduction has not been interrupted and that the reproduction has not ended in step 813, the process returns to step 811 to continue the reproduction process, and in step 813 it is determined that the reproduction process has ended. Then, in step 814, the reproduction time Tr is stored as the previous reproduction time Tro, and the reproduction time Tr is stored.
Is cleared, and this routine ends in step 815.

With the above control, even if the particulates remain around the filter in the previous regeneration process, or evenly remain on the portion away from the end face heater, the particulate filter is reproduced without deterioration. It is processed.

[0044]

As described above, according to the present invention,
Even if there is unburned particulate matter during the previous regeneration, there is an effect that the regeneration of the particulate filter can be completed satisfactorily without deteriorating the filter at the next regeneration of the particulate filter.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an overall configuration of an embodiment of an exhaust gas purifying apparatus for a single type internal combustion engine according to the present invention.

FIG. 2 is a flowchart showing an example of a regeneration processing operation of a control circuit in the exhaust gas purification device for an internal combustion engine of FIG. 1;

3 is an operation waveform diagram of a heater and an air pump in regeneration modes A, B, and C of FIG. 2;

FIG. 4 is a partial flowchart of a modified example of the flowchart in FIG. 2;

5A is a diagram showing a configuration of a secondary air supply device using an oxygen-enriched membrane, and FIG. 5B is a diagram showing a configuration of a secondary air supply device using a nitrogen and oxygen separator. FIG.

FIG. 6 is a diagram showing a configuration of a dual type exhaust gas purifying apparatus to which the present invention is applied.

FIG. 7 is a flowchart illustrating a regeneration process of a control circuit in the exhaust gas purification device for an internal combustion engine of FIG. 6;

FIG. 8 is a detailed flowchart of a part of the flowchart of FIG. 7;

9 is an operation waveform diagram of the heater and the air pump in the first to third regeneration modes of FIG. 9;

FIG. 10 is a system diagram showing the overall configuration of a conventional exhaust gas purification device for an internal combustion engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine 2 ... Exhaust gas passage 5, 51, 52 ... Particulate filter 6, 61, 62 ... Secondary air supply passage 7, 71, 72 ... Combustion gas discharge passage 8 ... Bypass passage 9, 91 ... Air pump 20 ... Exhaust gas purifier of one embodiment of the present invention 30 ... Dual filter type exhaust gas purifier implementing the present invention 50 ... Separator of nitrogen and oxygen 90 ... Oxygen-enriched film 100 ... Control circuit H, H1-H4 ... Electric heater SP1, SP2: Pressure sensors V1 to V5, V11, V21, V31, V41, VN
2, VO2 ... valve

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Terutaka Kageyama 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside of Denso Co., Ltd. (56) References JP-A-3-199614 (JP, A) JP-A-5 JP-A-5-156929 (JP, A) JP-A-3-43524 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01N 3/02 301 -341

Claims (2)

(57) [Claims] A filter provided in an exhaust gas passage of an internal combustion engine collects particulates in exhaust gas,
In the exhaust gas purifying apparatus, in which the particulates are ignited by heating by the heating means, and the regeneration gas is supplied by the regeneration gas supply means and the filter is regenerated by burning and burning the particulates, An internal combustion engine comprising: a particulate remaining amount detecting unit that detects an unburned amount; and a heating unit control unit that reduces a heating amount of the heating unit as the unburned amount near the heating unit increases. Engine exhaust purification device. 2. A particulate filter in an exhaust gas is collected by a filter provided in an exhaust gas passage of an internal combustion engine.
In the exhaust gas purifying apparatus, in which the particulates are ignited by performing heating by the heating means, and the regeneration gas is supplied by the regeneration gas supply means and burned at the same time to regenerate the filter, the particulate matter is contained in the filter. Particulate remaining amount detecting means for detecting whether there is unburned gas, and regeneration gas supply for reducing the amount of regeneration gas supplied from the regeneration gas supply means in the latter half of regeneration when there is unburned particulate matter An exhaust gas purifying apparatus for an internal combustion engine, comprising: