JP2018017142A - Pm purifier of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably purify PMs according to an exhaust temperature after maximally suppressing power consumption, in a PM purifier.SOLUTION: This PM purifier of an internal combustion engine comprises control means having a first calculation part for calculating a first parameter corresponding to an amount of collected PMs, a first processing execution part for executing first processing for oxidizing and removing the collected PMs when the first parameter is not smaller than a first prescribed value, a second calculation part for calculating a second parameter corresponding to an amount of discharged electrode accumulated PMs, and a second processing execution part for executing second processing for oxidizing and removing the discharged electrode accumulated PMs when the second parameter is not smaller than a second prescribed value. The first calculation part and the second calculation part calculate the first parameter and the second parameter so as to be larger when an exhaust temperature is high than the case that the exhaust temperature is low, or in the first processing and the second processing, the first prescribed value and the second prescribed value are set to be smaller when the exhaust temperature is high than the case that the exhaust temperature is low.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a PM purification device for an internal combustion engine.

  In the internal combustion engine, a filter is provided in the exhaust passage in order to prevent particulate matter (hereinafter also referred to as “PM”) in the exhaust from being discharged to the outside.

  Patent Document 1 discloses a technique using an electric dust collector as a filter for collecting PM. In this technique, PM charged by corona discharge performed in the exhaust passage is collected by a dust collection filter device including a dust collection electrode and a dust collection filter provided in the exhaust passage by Coulomb force. And in such an electric dust collector, PM collected by heating a heater is oxidized and removed (refer patent document 2).

JP 2009-1112916 A JP 2009-127442 A JP 2012-219673 A JP 2012-219770 A

  In the prior art relating to a PM purification device having a discharge electrode for performing corona discharge and a collection electrode for collecting charged PM that is paired with the discharge electrode, voltage application for oxidation removal of PM is always performed. If it is done, power consumption will become excessive. In the related art, when PM is deposited on the discharge electrode, there is a possibility that a short circuit occurs between the discharge electrode and the collection electrode. And if a short circuit arises between these electrodes, the PM purification rate in a PM purification apparatus will fall significantly.

  The present invention has been made in view of the above problems, and in the PM purification device, after suppressing the consumption of electric power as much as possible, the PM is suitably purified according to the exhaust temperature. Objective.

In order to solve the above problems, a PM purification apparatus for an internal combustion engine according to the present invention includes a discharge electrode disposed in an exhaust passage of the internal combustion engine, and the discharge electrode disposed so as to surround the discharge electrode in the exhaust passage. A collecting electrode that forms an electrode paired with the electrode, the collecting device from the discharge electrode side for particulate matter in the exhaust gas by applying a voltage to the discharge electrode A flow generating device that collects particulate matter on the collecting electrode by causing a flow of the particulate matter to the electrode for collecting, the discharge electrode and the collecting electrode of the flow generating device, And a dielectric disposed to surround at least a part of the processing electrode between the discharge electrode and the collecting electrode, and the collected PM removal. An apparatus for supplying power to the processing electrode. A collection PM removing device that oxidizes and removes collected PM, which is particulate matter collected by the collection electrode, by generating an oxidation promoting component outside the dielectric in the exhaust passage by application; A discharge electrode deposition PM removing apparatus having a heating means disposed on the discharge electrode, the discharge electrode deposition PM being particulate matter in exhaust gas deposited on the discharge electrode by heating the heating means. A discharge electrode deposition PM removal device that oxidizes and removes, a first purification unit that calculates a first parameter that is a parameter corresponding to the amount of the collected PM, and the first parameter is A first processing execution unit for executing a first processing for oxidizing and removing the collected PM by the collected PM removal device when the first predetermined value is exceeded, and a parameter corresponding to the amount of the discharge electrode deposition PM. A second calculation unit for calculating the second parameter, and a second process for oxidizing and removing the discharge electrode deposition PM by the discharge electrode deposition PM removal device when the second parameter is equal to or greater than a second predetermined value. A control means having a second process execution unit to execute, wherein the first calculation unit and the second calculation unit increase the first parameter and the second parameter when the exhaust gas temperature is high than when the exhaust temperature is low. In the first process and the second process, the first predetermined value and the second predetermined value are made smaller when the exhaust temperature is high than when the exhaust temperature is low.

  According to the present invention, in the PM purification device, it is possible to suitably purify PM according to the exhaust gas temperature while suppressing power consumption as much as possible.

It is a figure which shows schematic structure of the PM purification apparatus which concerns on the Example of this invention. The schematic diagram which looked at the discharge member of the PM purification apparatus shown in FIG. 1 from the vertical direction upper side is shown. The cross-sectional schematic diagram of the discharge member of PM purification apparatus shown in FIG. 1 is shown. It is a figure which shows the correlation with the 1st parameter and PM collection efficiency in the PM purification apparatus which concerns on a present Example. It is a figure which shows the correlation with the 2nd parameter and PM collection efficiency in the PM purification apparatus which concerns on a present Example. It is a figure which shows the time transition of PM collection efficiency when PM is collected by the flow generator of the PM purification apparatus which concerns on a present Example. It is a figure which shows the concept of the change of the particle diameter distribution of PM corresponding to the line L1 shown in FIG. It is a figure which shows the concept of the change of particle diameter distribution of PM corresponding to the line L3 shown in FIG. It is a block diagram which shows the function of the 1st parameter calculation part in ECU of a present Example. It is a block diagram which shows the function of the 2nd parameter calculation part in ECU of a present Example. It is a flowchart which shows the control flow at the time of the 1st process which concerns on a present Example being performed. It is a flowchart which shows the control flow at the time of the 2nd process which concerns on a present Example being performed. It is a flowchart which shows the control flow at the time of performing the 1st process which concerns on this modification. It is a block diagram which shows the function of the 1st parameter calculation part in ECU of this modification. It is a flowchart which shows the control flow at the time of the 2nd process which concerns on this modification being performed. It is a block diagram which shows the function of the 2nd parameter calculation part in ECU of this modification.

Hereinafter, specific embodiments of a PM purification apparatus for an internal combustion engine according to the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

<Example 1>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a PM purification device 1 according to the present embodiment. The PM purification device 1 is provided in the exhaust passage 2 of the diesel engine. It can also be provided in the exhaust passage of a gasoline engine. Here, in FIG. 1, the flow of exhaust is represented by an arrow 2a, the left side in FIG. 1 is the upstream side in the exhaust flow direction, and the right side in FIG. 1 is the downstream side in the exhaust flow direction.

  The PM purification device 1 includes a flow generation device 10 and a collected PM removal device 20. Since the flow generator 10 collects PM by generating a flow of PM charged by corona discharge, it may be referred to as a collector. Then, the PM collected by the flow generator 10 is oxidized and removed by the collected PM removal device 20.

  The flow generator 10 includes a discharge electrode 11. The discharge electrode 11 has a main portion 11a extending along the longitudinal direction of the exhaust passage 2, and a plurality of discharge protrusions each projecting from the main portion 11a so as to extend in a direction perpendicular to the longitudinal direction of the exhaust passage 2. 11b. The plurality of discharge protrusions 11b are provided at substantially constant intervals along the axial direction of the main portion 11a from the upstream side to the downstream side in the exhaust flow direction. Further, at the same position along the axial direction of the main portion 11a, a plurality of discharge projecting portions 11b are provided at substantially equal intervals. For example, when the number of the discharge protrusions 11b at the same position along the axial direction of the main part 11a is four, the discharge protrusions 11b are provided radially around the main part 11a at approximately 90 ° intervals. Furthermore, the discharge electrode 11 includes an insulator 11c and a silicone plug 11d, and an upstream end of the main portion 11a in the exhaust flow direction is connected to the insulator 11c. The insulator 11c is fixed to the exhaust pipe 3 forming the exhaust passage 2 with a silicone plug 11d. However, the insulator 11c may be fixed by a stopper composed of various insulating materials other than the silicone stopper. Further, the insulator 11c is configured such that an insulating member surrounds the conductive member, and the insulating member is fixed to the exhaust pipe 3 by a silicone plug 11d. The said insulating member is a product made from a ceramic or glass, for example, and can also be comprised with a various insulating material.

  In addition, the flow generator 10 includes an exhaust pipe 3 that forms a collection electrode 12 that is paired with the discharge electrode 11. In the present embodiment, since the exhaust pipe 3 has conductivity, the exhaust pipe 3 not only forms the exhaust passage 2 but also functions as a collecting electrode 12. Here, the exhaust pipe 3 may be formed so as to have conductivity as a whole, or may be formed so that only a part thereof has conductivity. When only a part of the exhaust pipe 3 is used as the collecting electrode 12 having conductivity, the tip of the discharge projecting portion 11b of the discharging electrode 11 is directed to the portion corresponding to the collecting electrode 12. It is good to be located in the position where it was, and it is good to locate at least in the portion of the exhaust pipe 3 in the perpendicular direction.

The flow generator 10 further includes a first voltage generator 13 in order to apply a voltage between the discharge electrode 11 and the collection electrode 12. The first voltage generator 13 is configured to generate a DC voltage. Note that the magnitude of the voltage is determined in advance by experiment or the like as a voltage that can negatively charge PM in the exhaust gas, and may be, for example, 7.5 kV or more. However, in this embodiment, there is no intention to limit the magnitude of the voltage within this range. And the 1st voltage generator 13 is connected to the insulator 11c of the electrode 11 for discharge through the conducting wire 13a, and on the other hand (the part not shown) is earth | grounded. Here, in the insulator 11c configured with the insulating member surrounding the conductive member, the main portion 11a of the discharge electrode 11 and the exhaust pipe 3 forming the collecting electrode 12 are insulated by the insulating member, A voltage is applied from the first voltage generator 13 to the main portion 11a and the discharge protrusion 11b by the conductive member. The first
While the voltage generator 13 is grounded, the exhaust pipe 3 forming the collecting electrode 12 is also grounded. Thus, a potential difference can be reliably generated between the discharge electrode 11 and the collection electrode 12 by applying a high voltage by the first voltage generator 13.

  Next, the collected PM removal device 20 includes a discharge member 21. The discharge member 21 includes a processing electrode 21a, a dielectric 21b, an insulator 21c, a silicone plug 21d, and a fibrous body 21e (see FIG. 3). The processing electrode 21a is covered with the dielectric 21b. The processing electrode 21a is a conductor member, and extends along the longitudinal direction of the exhaust passage 2, and is disposed so as to be substantially parallel to the longitudinal direction of the exhaust passage 2 except for a bent portion in FIG. Further, the processing electrode 21 a is provided in a portion of the exhaust pipe 3 that is vertically below, and a region where the plurality of discharge protrusions 11 b are arranged in the direction along the longitudinal direction of the exhaust passage 2. It is provided to cover at least. In the exhaust passage 2, PM may have a tendency to flow downstream due to the influence of the exhaust flow, so that the processing electrode 21 a is extended further downstream than the discharge projection 11 b on the most downstream side. Good. Here, the schematic diagram which looked at the discharge member 21 in FIG. 1 from the perpendicular direction upper side is shown in FIG. As shown in FIG. 2, the discharge member 21 has two processing units 22A and 22B. These processing units are composed of processing electrodes 21a and dielectrics 21b, and the first processing unit 22A is arranged adjacent to the second processing unit 22B, which is another processing unit. The first processing unit 22A is configured as one bent band-like part, and the second processing unit 22B is the same. Each processing electrode 21a included in these processing units is connected to an insulator 21c. The insulator 21c is fixed to the exhaust pipe 3 with a silicone plug 21d. However, the insulator 21c may be fixed by a stopper composed of various insulating materials other than the silicone stopper. Further, the insulator 21c is configured such that an insulating member surrounds the conductive member, and the insulating member is fixed to the exhaust pipe 3 by a silicone plug 21d. The said insulating member is a product made from a ceramic or glass, for example, and can also be comprised with a various insulating material.

  Furthermore, the cross-sectional schematic diagram of the discharge member 21 is shown in FIG. FIG. 3 is a schematic cross-sectional view of the first processing unit 22A and the second processing unit 22B along the line SS in FIG. As shown in FIG. 3, the processing electrode 21a and the dielectric 21b have a substantially circular cross section. A fibrous body 21e is provided on the surface of the dielectric 21b. The fibrous body 21e can be attached by directing a plurality of fibers using a so-called electrostatic flocking device. Further, the fibrous body 21e may be provided by other methods, for example, a plurality of fibers may be embedded in a predetermined position by hand or machine. As described above, each fiber of the fibrous body 21e configured with a plurality of fibers is made of ceramic whiskers, and the ceramic whiskers in this embodiment are SiC whiskers, but are made of other materials. May be. The fibrous body 21e has a moisture retention function and a PM trapping function.

  The discharge member 21 having the above-described configuration is arranged such that the dielectric 21b is in contact with the inner surface of the exhaust pipe 3. As described above, the exhaust pipe 3 has conductivity, and functions as an electrode (hereinafter, also referred to as “discharge member counter electrode”) as a pair of the processing electrode 21a. Thus, in the present embodiment, the exhaust pipe 3 functions not only as the collection electrode 12 paired with the discharge electrode 11 but also as the discharge member counter electrode paired with the processing electrode 21a. . When only a part of the exhaust pipe 3 is used as a discharge member counter electrode having conductivity, a portion corresponding to the discharge member counter electrode is preferably located at a position in contact with the dielectric 21b.

In addition, the collected PM removal device 20 further includes a second voltage generator 23 in order to apply a voltage between the processing electrode 21a and the discharge member counter electrode. The second voltage generator 23 is configured to generate an alternating voltage. Note that the magnitude of the voltage is determined in advance by experiments or the like, and may be, for example, about 12 kV and a frequency of 1 kHz. However, the present embodiment is not intended to be limited to this. And the 2nd voltage generator 23 is connected to the insulator 21c of the discharge member 21 via the conducting wire 23a and the switching device 23b, and on the other hand (the part not shown) is earth | grounded. Here, the first processing unit 22A and the second processing unit 22B illustrated in FIG. 2 are selectively connected to the second voltage generator 23 by switching the connection with the switching device 23b. Further, the insulator 21c formed by surrounding the conductive member with the insulating member is insulated from the processing electrode 21a and the exhaust pipe 3 forming the discharge member counter electrode by the insulating member. A voltage is applied from the two-voltage generator 23 to the processing electrode 21a. In addition, while the second voltage generator 23 is grounded, the exhaust pipe 3 that forms the discharge member counter electrode is also grounded. Therefore, when the voltage is applied by the second voltage generator 23, the processing electrode 21a and the discharge electrode 3 are discharged. A potential difference can be generated between the member counter electrode. Note that the second voltage generator 23 may be configured to generate a pulsed DC voltage.

  The PM purification device 1 further includes a discharge electrode deposition PM removal device 30. The discharge electrode deposition PM removal apparatus 30 has a heating wire 31 and a power source 32, and the heating wire 31 is connected to the power source 32 through a conducting wire 32a. Here, the heating wire 31 is wound around the surface of the insulator 11 c of the discharge electrode 11, and is provided in the vicinity of the fixing portion of the insulator 11 c to the exhaust pipe 3 in the exhaust passage 2. Yes.

  Here, the first voltage generator 13, the second voltage generator 23, and the power source 32 described above are a diesel engine (hereinafter referred to as “diesel engine of the present embodiment”) in which the PM purification device 1 according to the present embodiment is provided. It is electrically connected to an electronic control unit (ECU) 40 provided in the diesel engine as a unit for controlling the operation state of the diesel engine. The various devices are controlled by the ECU 40.

  The ECU 40 includes an accelerator position sensor 41, a crank position sensor 42, an air flow meter 43 provided in an intake passage (not shown), an exhaust temperature sensor 44 provided in the exhaust passage 2 upstream of the PM purification device 1, and the like. These various sensors are electrically connected. The accelerator position sensor 41 is a sensor that outputs an electrical signal correlated with an operation amount (accelerator opening) of an accelerator pedal (not shown). The crank position sensor 42 is a sensor that outputs an electrical signal correlated with the rotational position of the engine output shaft (crankshaft) of the diesel engine of this embodiment. The air flow meter 43 is a sensor that outputs an electrical signal corresponding to the amount (mass) of intake air (air) flowing in an intake passage (not shown). The exhaust temperature sensor 44 is a sensor that outputs an electrical signal corresponding to the temperature of the exhaust flowing in the exhaust passage 2 upstream of the PM purification device 1. The output signals of these sensors are input to the ECU 40. The ECU 40 derives the engine load of the diesel engine of this embodiment based on the output signal of the accelerator position sensor 41. Further, the ECU 40 derives the engine speed of the diesel engine of this embodiment based on the output signal of the crank position sensor 42. Further, the ECU 40 estimates the flow rate of the exhaust gas flowing into the PM purification device 1 based on the output signal of the air flow meter 43. Further, the ECU 40 detects the temperature of the exhaust gas flowing into the PM purification device 1 (hereinafter also referred to as “exhaust temperature”) based on the output signal of the exhaust gas temperature sensor 44.

  Here, the operation of the PM purification apparatus 1 having the above configuration will be described below. First, in the flow generator 10, when a high voltage from the first voltage generator 13 is applied to the discharge electrode 11, ions jump out from the discharge electrode 11, preferably the discharge protrusion 11 b toward the exhaust pipe 3. The PM flowing through the exhaust passage 2 in the exhaust pipe 3 is negatively charged. Then, an ion wind (not shown) induced by the ions is generated, and a flow from the discharge electrode 11 side to the exhaust pipe 3 side is generated. As a result, most of the PM contained in the exhaust is guided toward the exhaust pipe 3 in the exhaust passage 2, and most of the PM is collected on the inner surface of the exhaust pipe 3. The PM collected in this way preferably reaches the first processing unit 22A and the second processing unit 22B. Part of PM is affected by gravity and can be guided to these processing units on the lower side in the vertical direction. Part of the PM is captured by the fibrous body 21e.

  Next, in the collected PM removal device 20, when the AC high voltage from the second voltage generator 23 is applied to the processing electrode 21 a of the discharge member 21, particularly between the discharge member 21 and the exhaust pipe 3. A discharge phenomenon occurs near the contact portion between the dielectric 21b and the exhaust pipe 3. As a result, in the exhaust passage 2 in the exhaust pipe 3, PM oxidation promoting components such as ozone and active oxygen are generated around the dielectric 21 b and collected by the flow generator 10 on the inner surface of the exhaust pipe 3 for the first treatment. Oxidation of PM reaching the part 22A and the second processing part 22B is promoted. That is, the PM can be removed by oxidation (combustion removal). Here, as described above, the fibrous body 21e has a moisture holding function, and moisture in the exhaust gas that can be held by the fibrous body 21e can spread on the surface of the dielectric 21b. When moisture spreads around the dielectric 21b, the above discharge phenomenon can occur not only in the vicinity of the contact portion between the dielectric 21b and the exhaust pipe 3, but also in a wider range along this moisture presence region. That is, the discharge area is expanded by the moisture around the dielectric 21b.

  Further, in such a discharge phenomenon, an ion flow can occur. Here, as described above, the fibrous body 21e is oriented and provided on the surface of the dielectric 21b. As shown in FIG. 3, at least a part of the fibers of the dielectric 21b is adjacent to the processing unit side. It is oriented and provided. Therefore, for example, even when the PM is scattered on the ion flow generated by the discharge phenomenon in the first processing unit 22A, the PM can be directed to the adjacent second processing unit 22B by the fibrous body 21e. It will be. That is, after the voltage application to the first processing unit 22A by the second voltage generating device 23 is performed for a predetermined time, the switching device 23b connects the second voltage generating device 23 from the first processing unit 22A to the second processing unit 22B. By switching the PM, the PM scattered on the ion flow generated by the discharge phenomenon in the first processing unit 22A can be oxidized and removed as described above by the discharge phenomenon in the second processing unit 22B. And in the collection PM removal apparatus 20 which concerns on a present Example, the connection of the 1st process part 22A to the 2nd voltage generator 23 and the 2nd process part 22B to the 2nd voltage generator 23 by the switching apparatus 23b The PM collected by the flow generator 10 is oxidized and removed stepwise by the first processing unit 22A and the second processing unit 22B. Furthermore, by switching the processing unit in this way, the portion corresponding to the discharge member counter electrode of the processing unit that is not in the operating state in the exhaust pipe 3 collects PM as the collection electrode 12 in the flow generator 10. You can continue. Therefore, in the vicinity of the processing unit, PM collection by the flow generator 10 and PM oxidation removal by the collected PM removal device 20 can be performed in parallel.

  Here, as described above, in this embodiment, an oxidation promoting component is generated by applying a voltage to the processing electrode 21a included in the collected PM removing device 20, and the PM collected by the flow generating device 10 is oxidized and removed. However, if voltage application for PM oxidation removal is always executed, power consumption becomes excessive. Therefore, in the PM purification device 1 according to the present embodiment, the estimated amount of PM (hereinafter also referred to as “collected PM”) collected by the flow generator 10 on the inner surface of the exhaust pipe 3 by the ECU 40. (Hereinafter also referred to as “collected PM estimated amount”). Further, the ECU 40 calculates a “first parameter” that is a parameter corresponding to the collected PM estimated amount. As will be described later, the first parameter is calculated by multiplying the collected PM estimated amount by a first correction coefficient that changes according to the exhaust gas temperature. When the first parameter is equal to or greater than the first predetermined value, the ECU 40 applies a voltage to the processing electrode 21a using the second voltage generator 23 to generate an oxidation promoting component around the dielectric 21b. By doing so, the collected PM around the first processing unit 22A and the second processing unit 22B is oxidized and removed. In the following description, a process in which the ECU 40 oxidizes and removes the collected PM using the collected PM removing device 20 is referred to as a “first process”. In this embodiment, the ECU 40 functions as a first calculation unit according to the present invention by calculating the first parameter. In addition, the ECU 40 executes the first process, thereby functioning as a first process execution unit according to the present invention.

And in PM purification device 1 concerning this example, the 1st parameter and PM purification device 1
The ratio of the amount of PM collected per unit time by the flow generator 10 (hereinafter referred to as “PM collection efficiency”) to the amount of PM that flows in per unit time (hereinafter also referred to as “inflow PM amount”). 4) is shown in FIG. As shown in FIG. 4, the PM collection efficiency decreases as the first parameter increases. This means that when the first parameter is large, the amount of PM that flows into the PM purification device 1 and is not collected by the flow generator 10 becomes relatively large. PM that is not collected by the flow generator 10 flows out from the PM purification device 1 to the exhaust passage 2 on the downstream side, and the PM purification rate decreases. Therefore, in the PM purification apparatus 1 according to the present embodiment, when the first parameter is equal to or greater than the first predetermined value, the ECU 40 performs the first process to oxidize and remove the collected PM. As a result, the collected PM estimated amount becomes relatively small, and the first parameter correlated with the collected PM estimated amount becomes relatively small. At this time, the decrease in PM collection efficiency is recovered. Here, the value Q1 in FIG. 4 indicates the threshold value of the first parameter corresponding to the first predetermined value, and the first predetermined value is allowed as the emission of the vehicle on which the diesel engine of this embodiment is mounted. The first parameter corresponding to the PM collection efficiency (efficiency R1 shown in FIG. 4) determined based on the discharged PM amount is a value determined in advance based on experiments or the like. Thus, by performing the first process, voltage application to the processing electrode 21a of the collection PM removal device 20 is performed at an appropriate time, and the power consumption is suppressed as much as possible. In addition, PM can be purified.

  Further, in the PM purification apparatus 1 according to the present embodiment, the heating wire 31 is heated by the power supply from the power source 32 included in the discharge electrode deposition PM removal device 30 to the heating wire 31 and is deposited on the insulator 11 c of the discharge electrode 11. PM is oxidized and removed. In the present embodiment, the heating wire 31 corresponds to the heating means in the present invention.

  Here, as described above, when PM is deposited on the discharge electrode 11, a short circuit may occur between the discharge electrode 11 and the collection electrode 12. In the PM purification apparatus 1 according to the present embodiment, in particular, PM is present in the vicinity of the insulator 11c of the discharge electrode 11 that connects the main portion 11a of the discharge electrode 11 and the exhaust pipe 3 that forms the collection electrode 12. Easy to deposit. And if a short circuit arises between these electrodes, since the PM collection ability by the flow generator 10 may be lost, PM purification rate will fall significantly. Therefore, in the PM purification apparatus 1 according to the present embodiment, the estimated amount (hereinafter, “deposited PM estimation”) of the PM deposited on the discharge electrode 11 (hereinafter also referred to as “discharge electrode deposition PM”) by the ECU 40 is described. May be referred to as “amount”). Further, the ECU 40 calculates a “second parameter” that is a parameter corresponding to the accumulated PM estimation amount. As will be described later, the second parameter is calculated by multiplying the accumulated PM estimated amount by a second correction coefficient that changes according to the exhaust gas temperature. When the second parameter is equal to or greater than the second predetermined value, the ECU 40 heats the heating wire 31 using the power source 32 to oxidize and remove the discharge electrode deposition PM. In the following description, a process in which the ECU 40 oxidizes and removes the discharge electrode deposition PM using the discharge electrode deposition PM removal device 30 is referred to as a “second process”. In the present embodiment, the ECU 40 functions as a second calculation unit according to the present invention by calculating the second parameter. Further, the ECU 40 executes the second process, thereby functioning as a second process execution unit according to the present invention.

And the correlation of the 2nd parameter and PM collection efficiency in PM purification device 1 concerning this example is shown in FIG. As shown in FIG. 5, when the second parameter exceeds a certain value (value Q2 shown in FIG. 5), the PM collection efficiency is significantly reduced. That is, in such a case, the emission of the vehicle on which the diesel engine of this embodiment is mounted is greatly deteriorated. Therefore, in the PM purification apparatus 1 according to the present embodiment, when the second parameter is equal to or greater than the second predetermined value, the ECU 40 executes the second process to oxidize and remove the discharge electrode deposition PM. As a result, the estimated amount of accumulated PM becomes relatively small, and the second parameter correlated with the estimated amount of accumulated PM becomes relatively small. At this time, a significant decrease in PM collection efficiency is avoided. Here, the value Q2 in FIG. 5 indicates the threshold value of the second parameter corresponding to the second predetermined value, and the second predetermined value is determined in advance based on experiments or the like. Thus, by performing the 2nd process, it is avoided that a short circuit arises between the electrode 11 for discharge and the electrode 12 for collection, and the significant fall of PM purification rate is suppressed.

  Moreover, the time transition of PM collection efficiency when PM is collected by the flow generator 10 is shown in FIG. Here, in FIG. 6, the PM collection efficiency over time (line L1 shown in FIG. 6) when the exhaust temperature is low (low exhaust temperature), and the PM collection when the exhaust temperature is high (high exhaust temperature). The time transition of efficiency (line L3 shown in FIG. 6) and the time transition of PM collection efficiency when the exhaust temperature is between the low exhaust temperature and the high exhaust temperature (line L2 shown in FIG. 6) ) Comparison is also shown. As shown in FIG. 6, the PM collection efficiency decreases with the passage of time, and the PM collection efficiency at time t3 is lower than the PM collection efficiency at time t1, as illustrated by line L1. The line L2 also shows the same tendency as the line L1 in the period from the time t1 to the time t3. This is because when the exhaust gas temperature is the same, the first parameter increases with time, and as shown in FIG. 4 above, the PM collection efficiency decreases as the first parameter increases. ing. Here, in the flow generator 10, the PM charged by corona discharge from the discharge electrode 11 and guided toward the exhaust pipe 3 by the flow of ion wind has already been collected on the inner surface of the exhaust pipe 3. Colliding with the PM, the collected PM will re-scatter. And when there is much collection PM estimated amount, since the re-scattering of collection PM resulting from the collision of PM will occur easily, PM collection efficiency will become comparatively low.

  Here, as a result of intensive studies, the inventors of the present invention have found that the likelihood of re-scattering of the collected PM changes under the influence of the exhaust temperature. In order to explain this, the concept of the change in the particle size distribution of PM in the PM purification apparatus 1 according to the present embodiment will be described with reference to FIGS. 7A and 7B. FIG. 7A shows the concept of change in the particle size distribution of PM corresponding to the line L1 shown in FIG. 6, and the particle size distribution of PM at time t1, time t2, and time t3 is expressed as the particle size and the particle size. Expressed as a correlation with the number. As shown in FIG. 7A, the correlation between the particle diameter and the number of particles at time t1, time t2, and time t3 has the largest number of particles in the vicinity of the particle diameter d1. Thus, when the exhaust temperature is low, the particle diameter with the largest number of particles hardly changes with time. On the other hand, FIG. 7B shows the concept of change in the particle size distribution of PM corresponding to the line L3 shown in FIG. As shown in FIG. 7B, in the correlation between the particle diameter and the number of particles at time t1, the number of particles in the vicinity of the particle diameter d2 is the largest, and in the correlation between the particle diameter and the number of particles at time t3, The number of particles is the highest. Thus, when the exhaust gas temperature is high, there are many PMs having a relatively small particle diameter at the initial stage of PM collection by the flow generator 10, and particles are collected as PM collection by the flow generator 10 proceeds. There are many PMs with relatively large diameters. This indicates that when the exhaust gas temperature is high, the particle diameter of PM when flowing into the PM purification device 1 is relatively small. At this time, the PMs easily collide with each other in the process of collecting the PM by the flow generator 10, and the re-scattering of the collected PM occurs at a relatively high frequency due to the collision between the PMs. Conceivable. Thus, FIG. 7B shows that the re-scattering of the collected PM is likely to occur when the exhaust gas temperature is high. And PM is aggregated by repeating PM collection, a collision, and re-scattering, and the particle diameter of PM becomes relatively large. In summary, when the exhaust gas temperature is low, the particle diameter of the PM flowing into the PM purification device 1 is relatively large, and the occurrence frequency of re-scattering of the collected PM is considered to be relatively low. On the other hand, when the exhaust gas temperature is high, it is considered that the re-scattering of the collected PM occurs at a relatively high frequency due to the collision between PMs having relatively small particle diameters. When the exhaust temperature is high, re-scattering of the collected PM can occur at a higher frequency than when the exhaust temperature is low. Therefore, as shown in FIG. 6, the decrease in PM collection efficiency during the period from time t1 to time t3 is The line L2 and further the line L3 are larger than the line L1.

  Further, as indicated by a line L3 in FIG. 6, when the exhaust gas temperature is high, the PM collection efficiency sharply decreases at a certain time. At this time, a short circuit occurs between the discharge electrode 11 and the collection electrode 12. And this is also considered to be influenced by the ease of re-scattering of the collected PM described above. That is, when the exhaust gas temperature is high, re-scattering of the collected PM is likely to occur, and the re-scattered PM can accumulate on the insulator 11c of the discharge electrode 11, so that the discharge is caused by the re-scattered PM. When the electrode deposition PM increases and the second parameter exceeds the second predetermined value, the PM collection efficiency is significantly reduced. Note that when the exhaust temperature is low, the frequency of re-scattering of the collected PM is considered to be relatively low. Therefore, the discharge electrode deposition PM is unlikely to increase, and between the discharge electrode 11 and the collection electrode 12. Is less likely to occur (line L1 shown in FIG. 6), or even if a short circuit occurs, the time until the occurrence of the short circuit becomes longer (line L2 shown in FIG. 6).

  Therefore, in the PM purification apparatus 1 according to the present embodiment, the ECU 40 calculates the first parameter and the second parameter to be larger when the exhaust temperature is high than when the exhaust temperature is low. Below, the calculation method of a 1st parameter and a 2nd parameter is each demonstrated.

  FIG. 8 is a block diagram illustrating the function of the first parameter calculation unit in the ECU 40. The first parameter calculation unit 110 corresponding to the first calculation unit in the present invention is a functional unit for calculating the first parameter, and is realized by executing a predetermined program in the ECU 40.

  In the first parameter calculation unit 110, first, the amount of PM collected per unit time in the PM purification device 1 (hereinafter sometimes referred to as “PM collection amount”) is calculated. Specifically, the PM collection amount is calculated by multiplying the inflow PM amount by the PM collection efficiency. Here, the inflow PM amount is related to the operating state (engine rotational speed and engine load) of the diesel engine of the present embodiment. Therefore, if this relationship is obtained in advance by experiments or simulations, the inflow PM can be calculated from the operating state. The inflow PM amount can also be detected by a sensor. Further, the PM collection efficiency has a correlation with the collected PM estimated amount, and may reflect a tendency that, for example, the larger the collected PM estimated amount, the lower the PM collecting efficiency. Further, the PM collection efficiency has a correlation with the exhaust temperature, and may reflect a tendency that the PM collection efficiency becomes lower as the exhaust temperature is higher, for example. This is because the re-scattering of the collected PM described above has an effect, and the re-scattering of the collected PM becomes easier as the estimated amount of collected PM is larger or the exhaust gas temperature is higher. It tends to be less efficient. Such correlation is stored in advance in the ROM of the ECU 40 as a map or function, and the PM collection efficiency is calculated using this map or function. Then, in the first parameter calculation unit 110, the value of the collected PM estimated amount is then integrated by adding the previous value of the collected PM estimated amount to the value of the PM collected amount calculated in this way. Updated.

  Furthermore, the first parameter calculation unit 110 includes a first correction coefficient calculation unit 111, and the first correction coefficient calculation unit 111 has a first correction coefficient that is a coefficient for correcting the collected PM estimated amount. Calculated. Here, the first correction coefficient is a coefficient having a correlation with the exhaust temperature, and the likelihood of re-scattering of the collected PM changes according to the exhaust temperature described with reference to FIGS. 7A and 7B. Is a coefficient that takes into account That is, when the exhaust gas temperature is high, re-scattering of the collected PM is likely to occur, and the PM collection efficiency is lowered. Therefore, the first correction coefficient calculation unit 111 is more effective when the exhaust gas temperature is high than when the exhaust gas temperature is low. One correction coefficient is calculated so as to increase. Then, the first parameter is calculated by multiplying the collected PM estimated amount by the first correction coefficient. Therefore, the first parameter corrected by the first correction coefficient is larger when the exhaust gas temperature is high than when it is low even when the collected PM estimation amount is the same.

As described above, by calculating the first parameter, the first process that is executed when the first parameter is equal to or greater than the first predetermined value is executed at a more appropriate time according to the exhaust gas temperature. Thus, it is possible to suitably purify PM while suppressing power consumption as much as possible.

  FIG. 9 is a block diagram showing the function of the second parameter calculation unit in the ECU 40. The second parameter calculation unit 210 corresponding to the second calculation unit in the present invention is a functional unit for calculating the second parameter, and is realized by executing a predetermined program in the ECU 40.

  First, the second parameter calculation unit 210 calculates the amount of PM deposited on the discharge electrode 11 per unit time in the PM purification device 1 (hereinafter also referred to as “PM deposition amount”). Specifically, the PM accumulation amount is calculated by multiplying the inflow PM amount by the PM accumulation rate. Here, the inflow PM amount is calculated in the same manner as the first parameter calculation unit 110. The PM deposition rate is calculated using a correlation between the PM deposition rate stored in advance in the ROM of the ECU 40 as a map or function, and the collected PM estimated amount and the exhaust gas temperature. Then, in the second parameter calculation unit 210, the value of the accumulated PM estimated amount is updated by adding the previous value of the accumulated PM estimated amount to the value of the PM accumulated amount calculated in this way. .

  Furthermore, the second parameter calculation unit 210 includes a second correction coefficient calculation unit 211, and the second correction coefficient calculation unit 211 calculates a second correction coefficient that is a coefficient for correcting the estimated amount of accumulated PM. Is done. Here, the second correction coefficient is a coefficient having a correlation with the exhaust gas temperature, similar to the first correction coefficient described above, and the second correction coefficient calculator 211 re-scatters the collected PM according to the exhaust gas temperature. In consideration of the change in the likelihood of occurrence, the second correction coefficient is calculated to be larger when the exhaust temperature is high than when it is low. Then, the second parameter is calculated by multiplying the accumulated PM estimated amount by the second correction coefficient. Therefore, the second parameter corrected by the second correction coefficient is larger when the exhaust gas temperature is high than when it is low even when the estimated amount of accumulated PM is the same.

  As described above, by calculating the second parameter, the second process executed when the second parameter is equal to or greater than the second predetermined value is executed at a more appropriate time according to the exhaust gas temperature. Thus, the occurrence of a short circuit between the discharge electrode 11 and the collection electrode 12 is avoided, and a significant reduction in the PM purification rate is suppressed.

  Here, the control flow executed in the PM purification apparatus 1 according to the present embodiment will be described with reference to FIGS. 10 and 11.

  FIG. 10 is a flowchart illustrating a control flow when the first process according to the present embodiment is executed. In this embodiment, this flow is repeatedly executed by the ECU 40 at a predetermined calculation cycle during operation of the diesel engine of this embodiment.

  In this flow, first, in S101, the ECU 40 acquires the engine rotation speed of the diesel engine of the present embodiment based on the output signal of the crank position sensor 42, and based on the output signal of the accelerator position sensor 41 of the present embodiment. The engine load of the diesel engine is acquired, and the exhaust temperature is acquired based on the output signal of the exhaust temperature sensor 44.

  Next, in S102, the first parameter Pr1 is calculated. In S102, the first parameter Pr1 is calculated by the first parameter calculation unit 110 described above.

Next, in S103, the threshold Pr1th of the first parameter stored in the ROM of the ECU 40 is read. The threshold value Pr1th is a value corresponding to the first predetermined value described above, and is determined in advance based on experiments or the like and stored in the ROM of the ECU 40. Then, after the process of S103, in S104, it is determined whether or not the first parameter Pr1 is greater than or equal to the threshold value Pr1th. If an affirmative determination is made in S104, the ECU 40 proceeds to the process of S105, and if a negative determination is made in S104, the execution of this flow is terminated.

  If an affirmative determination is made in S104, then a first process execution time ts1 is calculated in S105. In S105, the first processing execution time ts1 is calculated so that the collected PM can be oxidized and removed. This value is the collected PM estimated amount Qtr calculated by the first parameter calculating unit 110 in the process of calculating the first parameter Pr1 in S102, the collected PM estimated amount Qtr0 at the end of the first process, and the first process. Calculated based on the oxidation rate of the collected PM and the amount of PM collected, which is the amount of PM collected per unit time in the PM purification device 1. For example, these correlations are stored in advance in the ROM of the ECU 40. Yes.

  Next, in S106, the first process is executed. The collected PM is oxidized and removed by executing the first process, but in S106, the collected PM removing device 20 is set so that the oxidation rate of the collected PM by the first process is larger than the amount of collected PM. The magnitude of the voltage applied to the processing electrode 21a of the is controlled. As a result, the collected PM can be reliably reduced.

  Next, in S107, it is determined whether or not the first process execution time ts1 has elapsed since the execution of the first process was started. If an affirmative determination is made in S107, the ECU 40 proceeds to the process of S108, and if a negative determination is made in S107, the ECU 40 returns to the process of S106.

  If an affirmative determination is made in S107, then in S108, the value of the collected PM estimated amount Qtr is updated to the value of the collected PM estimated amount Qtr0 at the end of the first process. The execution of is terminated.

  FIG. 11 is a flowchart showing a control flow when the second process according to the present embodiment is executed. In this embodiment, this flow is repeatedly executed by the ECU 40 at a predetermined calculation cycle during operation of the diesel engine of this embodiment.

  In this flow, first, in S201, the ECU 40 acquires the engine rotation speed of the diesel engine of the present embodiment based on the output signal of the crank position sensor 42, and based on the output signal of the accelerator position sensor 41 of the present embodiment. The engine load of the diesel engine is acquired, and the exhaust temperature is acquired based on the output signal of the exhaust temperature sensor 44.

  Next, in S202, the second parameter Pr2 is calculated. In S202, the second parameter Pr2 is calculated by the second parameter calculation unit 210 described above.

  Next, in S203, the second parameter threshold value Pr2th stored in the ROM of the ECU 40 is read. This threshold value Pr2th is a value corresponding to the second predetermined value described above, and is determined in advance based on experiments or the like and stored in the ROM of the ECU 40. Then, after the process of S203, in S204, it is determined whether or not the second parameter Pr2 is greater than or equal to the threshold value Pr2th. If an affirmative determination is made in S204, the ECU 40 proceeds to the process of S205. If a negative determination is made in S204, the execution of this flow is terminated.

If an affirmative determination is made in S204, the second process execution time ts2 is then calculated in S205. In S205, the second processing execution time ts2 is calculated so that the discharge electrode deposition PM can be oxidized and removed. This value is the accumulated PM estimated amount Qdp calculated by the second parameter calculating unit 210 in the process of calculating the second parameter Pr2 in S202, the accumulated PM estimated amount Qdp0 at the end of the second process, and the discharge electrode by the second process. It is calculated on the basis of the oxidation rate of the deposited PM and the PM deposition amount that is the PM amount deposited on the discharge electrode 11 per unit time in the PM purification apparatus 1. For example, these correlations are stored in advance in the ROM of the ECU 40. ing.

  Next, in S206, the second process is executed. The discharge electrode deposition PM is removed by oxidation by executing the second process, but in S206, the discharge electrode deposition PM removal is performed so that the oxidation rate of the discharge electrode deposition PM by the second process is larger than the PM deposition amount. The magnitude | size of the voltage applied to the heating wire 31 which the apparatus 30 has is controlled. As a result, the discharge electrode deposition PM can be reliably reduced.

  Next, in S207, it is determined whether or not the second process execution time ts2 has elapsed since the execution of the second process was started. If an affirmative determination is made in S207, the ECU 40 proceeds to the process of S208, and if a negative determination is made in S207, the ECU 40 returns to the process of S206.

  If an affirmative determination is made in S207, then, in S208, the value of the accumulated PM estimated amount Qdp is updated to the value of the accumulated PM estimated amount Qdp0 at the end of the second process, and after the process of S208, execution of this flow is performed. Is terminated.

  According to the present embodiment, when the first process is executed in the control flow shown in FIG. 10, the voltage application to the processing electrode 21a of the collection PM removal device 20 is low when the exhaust temperature is high. It is executed earlier, and it is possible to suitably purify the PM while suppressing power consumption as much as possible. Further, in this embodiment, the second process is executed independently of the first process. However, since the discharge electrode deposition PM that is oxidized and removed by the execution of the second process can be caused by re-scattering of the collected PM that can be oxidized and removed by the execution of the first process, the execution of the second process is performed. It can be said that the execution status of the first process has an effect on. Then, by executing the second process in the control flow shown in FIG. 11, the second process is performed earlier when the exhaust gas temperature is high than when the exhaust temperature is low. A short circuit with the working electrode 12 is avoided, and a significant reduction in the PM purification rate is suppressed.

<Modification 1>
In the first embodiment, when the exhaust temperature is high, the first parameter and the second parameter are calculated to be larger than when the exhaust temperature is low. On the other hand, this modification is an example in which the first predetermined value and the second predetermined value are made smaller when the exhaust gas temperature is high than when it is low. In this modification, the detailed description of the substantially same configuration and substantially the same control processing as in the first embodiment will be omitted.

  Here, the control flow executed in the PM purification apparatus 1 according to this modification will be described based on FIGS. 12 and 14.

  FIG. 12 is a flowchart showing a control flow when the first process according to this modification is executed. In this modification, this flow is repeatedly executed by the ECU 40 at a predetermined calculation cycle during operation of the diesel engine provided with the PM purification device 1 according to this modification.

In this flow, after the process of S101, the first parameter Pr1 ′ is calculated in S302. In S302, the first parameter Pr1 ′ is calculated by the first parameter calculation unit 310 corresponding to the first parameter calculation unit 110 of the first embodiment. Here, a block diagram showing the function of the first parameter calculation unit 310 is shown in FIG. As shown in FIG. 13, unlike the first parameter calculation unit 110 of the first embodiment, the first parameter calculation unit 310 does not correct the collected PM estimated amount. That is, the collected PM estimated amount is calculated as the first parameter.

  Next, in S303, a threshold Pr1′th of the first parameter is calculated. In S303, the first parameter threshold value Pr1th is read in the same manner as in the first embodiment. Then, the threshold value Pr1′th of the first parameter is calculated by correcting the threshold value Pr1th with a third correction coefficient that is a correction coefficient that changes according to the exhaust gas temperature. Specifically, the threshold value Pr1′th of the first parameter is calculated by multiplying the threshold value Pr1th stored in the ROM of the ECU 40 by the third correction coefficient. Here, the third correction coefficient has a correlation with the exhaust gas temperature, and is made smaller when the exhaust gas temperature is high than when it is low. Therefore, the threshold value Pr1′th corrected by the third correction coefficient is smaller when the exhaust temperature is high than when it is low. Then, after the process of S303, in S304, it is determined whether or not the first parameter Pr1 ′ is greater than or equal to the threshold value Pr1′th. If an affirmative determination is made in S304, the ECU 40 proceeds to the process of S105, and if a negative determination is made in S304, the execution of this flow is terminated.

  FIG. 14 is a flowchart showing a control flow when the second process according to this modification is executed. In this modification, this flow is repeatedly executed by the ECU 40 at a predetermined calculation cycle during operation of the diesel engine provided with the PM purification device 1 according to this modification.

  In this flow, after the process of S201, the second parameter Pr2 ′ is calculated in S402. In S402, the second parameter Pr2 ′ is calculated by the second parameter calculation unit 410 corresponding to the second parameter calculation unit 210 of the first embodiment. Here, a block diagram showing the function of the second parameter calculation unit 410 is shown in FIG. As shown in FIG. 15, in the second parameter calculation unit 410, unlike the second parameter calculation unit 210 of the first embodiment, the accumulated PM estimated amount is not corrected. That is, the accumulated PM estimated amount is calculated as the second parameter.

  In step S403, a second parameter threshold value Pr2′th is calculated. In S403, the second parameter threshold value Pr2th is read in the same manner as in the first embodiment. Then, the threshold value Pr2′th of the second parameter is calculated by correcting the threshold value Pr2th with a fourth correction coefficient that is a correction coefficient that changes according to the exhaust gas temperature. Specifically, the threshold value Pr2′th of the second parameter is calculated by multiplying the threshold value Pr2th stored in the ROM of the ECU 40 by the fourth correction coefficient. Here, the fourth correction coefficient is a coefficient having a correlation with the exhaust gas temperature, and is made smaller when the exhaust gas temperature is high than when it is low. Therefore, the threshold value Pr2′th corrected by the fourth correction coefficient is smaller when the exhaust temperature is high than when it is low. Then, after the process of S403, in S404, it is determined whether or not the second parameter Pr2 ′ is greater than or equal to the threshold value Pr2′th. If an affirmative determination is made in S404, the ECU 40 proceeds to the process of S205. If a negative determination is made in S404, the execution of this flow is terminated.

  Also according to this modification, voltage application to the processing electrode 21a of the collection PM removal device 20 is executed earlier when the exhaust gas temperature is high than when it is low, thereby consuming as much power as possible. It becomes possible to purify PM suitably after suppressing. Further, when the exhaust gas temperature is high, the second treatment is performed earlier than when the exhaust temperature is low, and it is avoided that a short circuit occurs between the discharge electrode 11 and the collection electrode 12, and the PM purification rate Is significantly reduced.

DESCRIPTION OF SYMBOLS 1 ... PM purification apparatus 2 ... Exhaust passage 3 ... Exhaust pipe 10 ... Flow generator 11 ... Discharge electrode 12 ... Collection electrode 13 ... First voltage generator 20 ... Trap Collecting PM removal device 21 .. Discharge member 21a .Processing electrode 21b .Dielectric 22A .First treatment unit 22B .Second treatment unit 23 ..Second voltage generator 30 ..Discharge electrode deposition PM removal device 31. Heating wire 32 ・ ・ Power supply 40 ・ ・ ECU

Claims (1)

A flow generator comprising: a discharge electrode disposed in an exhaust passage of an internal combustion engine; and a collection electrode disposed so as to surround the discharge electrode in the exhaust passage and forming an electrode paired with the discharge electrode An apparatus for applying the voltage to the discharge electrode to cause the particulate matter in the exhaust gas to flow from the discharge electrode side to the collection electrode side, thereby collecting the collection material. A flow generator that collects particulate matter on the electrodes for use;
A processing electrode disposed between the discharge electrode and the collecting electrode of the flow generator; and at least a part of the processing electrode between the discharge electrode and the collecting electrode. A collecting PM removing device including a dielectric disposed so as to surround, and generating an oxidation promoting component outside the dielectric in the exhaust passage by applying a voltage to the processing electrode. A collected PM removal device that oxidizes and removes collected PM that is particulate matter collected by the collecting electrode;
A discharge electrode deposition PM removing apparatus having a heating means disposed on the discharge electrode, the discharge electrode deposition PM being particulate matter in exhaust gas deposited on the discharge electrode by heating the heating means. A PM purification device having a discharge electrode deposition PM removal device for oxidizing and removing
A first calculator that calculates a first parameter that is a parameter corresponding to the amount of the collected PM;
When the first parameter is equal to or greater than a first predetermined value, a first process execution unit that executes a first process of oxidizing and removing the collected PM by the collected PM removal device;
A second calculation unit that calculates a second parameter that is a parameter corresponding to the amount of the discharge electrode deposition PM;
And a second process execution unit that executes a second process of oxidizing and removing the discharge electrode deposition PM by the discharge electrode deposition PM removal device when the second parameter is equal to or greater than a second predetermined value. Prepared,
The first calculation unit and the second calculation unit calculate the first parameter and the second parameter to be larger when the exhaust temperature is high than when the exhaust temperature is low, or the first process and the second parameter In the processing, when the exhaust temperature is high, the first predetermined value and the second predetermined value are made smaller than when the exhaust temperature is low.
PM purification device for internal combustion engine.

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