JP2018054402A - Sof (soluble organic fraction) amount calculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a SOF amount calculation device capable of accurately calculating a SOF amount.SOLUTION: A SOF amount calculation device is connected to a sensor which has: at least one accumulation section which is made of a porous material so as to allow particulate matters in exhaust gas to accumulate on a surface thereof; at least one pair of electrodes arranged to face each other with the accumulation section in between; and an exothermic body which heats at least one accumulation section. The SOF amount calculation device comprises: a temperature acquisition unit which acquires a signal corresponding to a temperature of at least one accumulation section; a power supply unit which controls power supply to the exothermic body in a manner that heats the accumulation section at a first temperature allowing a SOF contained in the particulate matters to be burnt but not allowing soot to be burnt on the basis of the signal acquired by the temperature acquisition unit; and a first derivation unit which derives a SOF amount on the basis of a period from a start of the power supply to the exothermic body until when electrostatic capacity between the pair of electrode becomes almost constant and a variation in the electrostatic capacity between the pair of electrodes.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an SOF amount calculation device.

  A conventional SOF amount calculation device is described in Patent Document 1, for example. In Patent Document 1, the ECU uses the temperature of the exhaust gas flowing through each exhaust pipe, the rotational speed of the diesel engine, and the fuel injection amount to each cylinder to determine the SOF adsorbed to each DPF for each fuel injection. The amount of adsorption is calculated.

JP 2011-163202 A

  However, the conventional SOF calculation apparatus has a problem that it is difficult to calculate a highly accurate SOF adsorption amount.

  An object of the present disclosure is to provide an SOF amount calculation apparatus that can calculate a more accurate SOF amount.

One aspect of the present disclosure is:
At least one deposition part made of a porous material and on which the particulate matter contained in the exhaust gas is deposited, at least a pair of electrodes facing each other across the at least one deposition part, and the at least one deposition An SOF amount calculating device connected to a sensor including a heating element that heats the unit,
A temperature acquisition unit for acquiring a signal according to the temperature of the at least one deposition unit;
Based on the signal acquired by the temperature acquisition unit, power is supplied to the heating element so as to heat the deposition unit at a first temperature at which soluble organic components contained in the particulate matter can be combusted but soot does not combust. A power supply to control;
Based on the time from the start of power supply to the heating element until the capacitance between the pair of electrodes becomes substantially constant, and the amount of change in capacitance between the pair of electrodes, A first deriving unit for deriving the amount of the soluble organic component;
Directed to.

  According to the present disclosure, it is possible to provide an SOF amount calculation apparatus that can calculate a more accurate SOF amount.

The figure which shows the SOF amount calculation apparatus which concerns on one Embodiment of this indication, and its periphery structure The figure which shows the detailed structure of PM sensor of FIG. The perspective view which shows the typical structure of the sensor part of FIG. 3A is an exploded perspective view of the sensor unit of FIG. 3A. FIG. 1 is a flowchart of the SOF amount calculation apparatus of FIG.

  Hereinafter, the SOF amount calculation apparatus 1 according to the present disclosure will be described in detail with reference to the drawings. Prior to that, terms are first defined.

<1. Definition>
Table 1 below shows the meaning of acronyms and abbreviations used in this embodiment.

  In some of the drawings, the L axis, the W axis, and the T axis that are orthogonal to each other are drawn. An L axis, a W axis, and a T axis indicate a length direction, a width direction, and a height direction of the sensor 7 to be described later. Hereinafter, the direction indicated by the L axis may be referred to as the length direction L, the direction indicated by the W axis as the width direction W, and the direction indicated by the T axis as the height direction T. Further, the positive direction side of the L axis may be referred to as the front end side, and the negative direction side thereof may be referred to as the rear end side.

<2. Configuration of SOF Quantity Calculation Device, etc.>
In FIG. 1, a vehicle V is equipped with an internal combustion engine 3, an exhaust system 5, and a sensor 7 in addition to the SOF amount calculation device 1.

  First, the internal combustion engine 3 will be described. The internal combustion engine 3 is, for example, a diesel engine, and includes a combustion chamber 301, an injector 303, an intake valve 305, and an exhaust valve 307.

  The combustion chamber 301 is a space surrounded by the top of the piston 311, the cylinder 313, the cylinder head 315, and the like.

  In the present disclosure, the injector 303 injects fuel into the combustion chamber 301. However, the present invention is not limited to this, and the injector 303 may inject fuel into the intake port of the combustion chamber 301.

  Each of the intake valve 305 and the exhaust valve 307 is configured to be openable and closable. When the intake valve 305 is opened, fresh air from the intake passage 317 is drawn into the combustion chamber 301. Further, when the exhaust valve 307 is opened, the exhaust gas generated by the combustion of fuel in the combustion chamber 301 is sent out to the exhaust system 5 (specifically, the exhaust passage 501).

Next, the basic configuration of the exhaust system 5 will be described.
The exhaust system 5 has an exhaust passage 501 that guides exhaust gas generated in the internal combustion engine 3 to the atmosphere (outside the vehicle). In the present disclosure, the exhaust flow path 501 is provided with a DOC 503A and a CSF 503B as examples of the post-processing device 503.

  The DOC 503A is an oxidation catalyst, and is provided on the most upstream side of the exhaust passage 501 in the example of the post-processing device 503. The DOC 503A has, for example, a cylindrical shape and includes a honeycomb carrier made of ceramic. A number of through holes are formed in this honeycomb carrier. The honeycomb wall surface surrounding these through holes is supported or coated with a noble metal catalyst such as platinum.

  The DOC 503A, for example, raises the temperature of the CSF 503B by reacting unburned fuel in the exhaust gas that has flowed into itself through the exhaust passage 501 with an oxidation catalyst, or at least a part of nitrogen oxide (hereinafter referred to as NOx). Or nitrogen dioxide to increase the ratio of nitrogen dioxide in the exhaust gas (NOx).

  The CSF 503B is provided on the downstream side of the DOC 503A in the exhaust passage 501. The CSF 503B is a so-called wall flow filter, which is made of ceramic and has a cylindrical honeycomb carrier.

  When the CSF 503B is manufactured, a large number of through holes penetrating both end faces are formed in the honeycomb carrier, and then the openings on the upstream end face and the downstream end face are alternately sealed to form half through holes (ie, cells). . As a result, from the opening on the upstream end face (that is, the opening of the cell) through the half through hole, the honeycomb wall surface (the partition wall of two adjacent cells) and the half through hole, the opening on the downstream end face (of the adjacent cell). An exhaust gas flow path to the opening) is formed. Here, the honeycomb wall surface is used as a filtration surface. A noble metal catalyst may be supported or coated on the honeycomb wall surface.

  The CSF 503B as described above is disposed on the downstream side of the DOC 503A in the exhaust passage 501. In the CSF 503B, the exhaust gas guided through the exhaust flow path 501 passes through the flow path. In the process, particulate matter (mainly soot) in the exhaust gas is deposited and collected on the upstream surface of the honeycomb wall surface.

  Further, if the temperature of the exhaust gas is equal to or higher than the self-regeneration temperature, the CSF 503B burns and removes the collected soot (so-called self-regeneration). Here, the weight ratio of nitrogen dioxide in the exhaust gas is important for self-regeneration (that is, soot combustion) in the CSF 503B. Therefore, the self-regeneration is performed by combining the DOC 503A and the CSF 503B.

  Note that the same oxidation catalyst as that of the DOC 503A may be added to the CSF 503B itself. Also in this case, the CSF 503B can self-regenerate in the same manner as described above.

  The exhaust gas that has passed through the CSF 503B is treated with a well-known SCR, RDOC, and the like, rendered harmless, and then discharged into the atmosphere through a muffler (not shown).

  The sensor 7 is disposed upstream of the CSF 503 </ b> B in the exhaust flow path 501, and outputs an electric signal indicating a capacitance that changes according to the amount of PM contained in the exhaust gas passing through the sensor 7 to the control device 1. Here, since the SOF amount calculation device 1 is intended to calculate the amount of SOF contained in the PM, the sensor 7 may be disposed upstream of the DOC 503A in the exhaust passage 501.

Hereinafter, the sensor 7 shown in FIG. 1 will be described with reference to FIGS. 2, 3A, and 3B.
In addition, in FIG. 2, regarding both cases 701 and 703, the cross-sectional shape when each part is cut | disconnected along the virtual plane parallel to WL plane is shown. As for the sensor unit 705, a cross-sectional shape when the sensor unit 705 is cut along the virtual plane is shown.

  2 to 3B, the sensor 7 includes, for example, an outer case 701 and an inner case 703, a sensor unit 705, at least one heating element 707, a temperature sensor 709, and a mounting unit 711.

  The outer case 701 has, for example, a cylindrical shape having a central axis extending in the length direction L. Both ends of the outer case 701 in the length direction L are not closed and are openings having an inner diameter of φa.

  The inner case 703 has, for example, a bottomed cylindrical shape having a central axis extending in the length direction L. In the present disclosure, the inner case 703 has a size larger than the outer case 701 in the length direction L. Further, the outer diameter φb of the inner case 703 is smaller than the inner diameter φa. Further, the rear end portion of the inner case 703 is not closed, but is an opening having an inner diameter φc.

  Further, in the vicinity of the rear end portion of the inner case 703, a plurality of intake ports (through holes) Hin are formed along the circumferential direction of the outer peripheral surface in order to take in the exhaust gas. In addition, from the viewpoint of the visibility of a figure, in FIG. 2, the reference sign Hin is attached | subjected only to one intake port.

  Moreover, the front-end | tip part of the inner case 703 becomes the bottom part in the length direction L, and is substantially closed although not perfect. More specifically, at approximately the center of the bottom portion, at least one discharge port (through hole) Hout having a smaller diameter than the inner diameter φc is provided in order to return the exhaust gas inside the inner case 703 to the exhaust passage 501. It is formed.

  As shown in FIGS. 3A and 3B, the sensor unit 705 includes a porous body 7051 and at least two electrodes 7053 (in the figure, five electrodes 7053A to 7053E) that form a pair.

  The porous body 7051 is a wall flow type filter similar to the CSF 503B, is made of a laminate of porous ceramic sheets having electrical insulation, and has a substantially rectangular parallelepiped shape extending in the length direction L.

  This porous body 7051 is also formed with a plurality of through-holes passing through opposite end faces (that is, the upstream end face and the downstream end face) opposed to each other in the length direction L, and then the upstream end face and the downstream end face are formed. The openings are alternately sealed to form half through holes (ie, cells). Thereby, inside the porous body 7051, from the opening on the upstream end face (that is, the opening of the cell), through the semi-through hole, the honeycomb wall surface (the partition wall of two adjacent cells) and the semi-through hole, A flow path for the exhaust gas reaching the opening on the downstream end face (opening of the adjacent cell) is formed. Here, the honeycomb wall surface is used as a filtration surface.

  In FIG. 3A, the upstream end face is drawn so as to be visible, and the reference numeral C1 is given to the three cells sealed at the upstream end face. Further, the reference cell C2 is attached to the two cells opened at the upstream end face.

  Each electrode 7053 is made of a planar conductor, and is embedded, for example, one by one in the honeycomb wall of the porous body 7051 substantially parallel to the LW plane. As a result, two electrodes 7053 adjacent in the T-axis direction face each other across, for example, one row of cells C1 and C2 arranged in the width direction W to form a capacitor.

  At least one heating element 707 is made of a linear conductor and is embedded in the honeycomb wall. In the present disclosure, two heating elements 707A and 709B are exemplified. Each heating element 707 generates heat by the electric power supplied under the control of the SOF amount calculating device 1 and burns PM deposited on the honeycomb wall surface constituting the porous body 7051. From this point of view, each heating element 707 is preferably made of a linear conductor having a narrow width as much as possible and meandering.

  Note that at least one electrode 7053 can have the function of the heating element 707.

  The temperature sensor 709 is, for example, a thermistor having a positive or negative temperature characteristic, and outputs a signal corresponding to the temperature of the porous body 7051 (particularly, a deposition portion) to the control device 1. Specifically, the temperature sensor 709 may be a chip type and mounted on the surface of the porous body 7051, or may be embedded in the honeycomb wall surface in the same manner as the electrodes 7053.

  In addition, from each electrode 7053 (in the present disclosure, electrodes 7053A to 7053E), a conducting wire 713 (in the present disclosure, conducting wires 713A to 713E) is drawn one by one (see FIG. 3A).

  In addition, a pair of conductors 715 (a pair of conductors 715A and 715B in the present disclosure) are drawn from both ends of each heating element 707 (in the present disclosure, the heaters 707A and 707B).

  Further, one lead wire 717 is drawn out from each of both external electrodes of the temperature sensor 709.

  Reference is again made to FIG. The attachment portion 711 generally has a ring shape. Both cases 701 and 703 are inserted and fixed to the front end side of the mounting portion 711. At the time of insertion, (1) the central axes of both cases 701 and 703 are parallel and aligned with the L axis, and (2) the inner case 703 is accommodated in the inner space of the outer case 701. Further, in the present disclosure, (3) the front end portion of the inner case 703 protrudes toward the positive direction side of the L axis from the front end portion of the outer case 701.

  The sensor unit 705 configured as described above is press-fitted into the inner space of the inner case 513 with the side surfaces except the upstream end surface and the downstream end surface wound with a heat-resistant mat. As a result, the porous body 7051 is arranged in the inner case 703 such that each half through hole is along the flow direction of the exhaust gas. In the porous body 7051, the exhaust gas guided to the inside of the inner case 513 passes through the flow path. In the process, particulate matter (including soot and SOF) in the exhaust gas is deposited and collected on the upstream surface of the honeycomb wall surface. Thus, the honeycomb wall surface is an example of a deposition portion.

  A male screw S <b> 2 is formed on the outer peripheral surface of the attachment portion 711. Further, a boss B2 is provided upstream of the CSF 503B in the exhaust passage 501, and a through-hole penetrating the exhaust passage 501 in the length direction L is formed in the boss B2. A female screw S4 into which the male screw S2 is screwed is cut on the inner peripheral surface of the through hole. The sensor 7 is attached to the exhaust passage 501 by the mounting portion 711 and the female screw S4 of the exhaust passage 501 as described above. At this time, the size of the sensor 7 is designed so that the discharge port Hout is located on or near the central axis of the exhaust flow path 501 at which a relatively large flow velocity is obtained in the exhaust flow path 501.

  The attachment portion 711 is formed with a through hole H2 that penetrates along the length direction L and through which a conductive wire 713 described later passes. Each of the conducting wires 713 to 717 is connected to the SOF amount calculating device 1 through the through hole H2.

  The SOF amount calculating device 1 supplies power to the heating element 707 based on the output signal of the temperature sensor 709 and burns SOF while maintaining the temperature of the porous body 7051 in the sensor 7 at the first temperature. Thus, the amount of soot accumulated on the porous body 7051 of the sensor 7 is detected.

  The SOF amount calculation device 1 is an ECU in which a connector, a measurement circuit, a microcomputer, a working memory, a program memory, and the like are mounted on a substrate.

The conductors 713, 715, and 717 are connected to the connector, and a known measurement circuit is connected to the connector.
The measurement circuit detects the combined capacitance of all pairs of the electrodes 7053 by a well-known method, and outputs it to the microcomputer. A method for measuring the composite capacity is described in, for example, Japanese Patent Application Laid-Open No. 2011-169205. In addition, the capacitance can be measured using a known LCR meter.

  The microcomputer executes a program stored in advance in the program memory using the working memory.

<3. Processing of SOF amount calculating apparatus 1>
Next, the process of the SOF amount calculating device 1 will be described with reference to FIG.
In FIG. 4, the microcomputer acquires the temperature of the exhaust gas by a well-known method (step S001).

  The temperature of the exhaust gas can be obtained from, for example, an output signal of a temperature sensor (not shown) provided on the upstream side of the CSF 503B in the exhaust passage 501. In addition, the temperature represented by the output signal of the temperature sensor 709 may be regarded as the exhaust gas temperature.

  Next, the microcomputer determines whether or not the temperature acquired in step S001 is equal to or lower than a temperature threshold (step S003). The temperature threshold value is derived by an experiment or the like at the design and development stage of the SOF amount calculating apparatus 1 and is selected to be a value obtained by adding a predetermined margin to the SOF oxidation temperature. That is, SOF is included in the exhaust gas generated in the internal combustion engine 3 when the vehicle is in a low load operation or the like, and can affect the detection accuracy of the soot amount using the sensor 7. However, since the SOF is oxidized when the exhaust gas reaches a high temperature of about 200 ° C. or higher, it does not affect the detection value of the soot amount using the sensor 7.

  If NO is determined in step S003, the microcomputer detects the combined capacitance of all pairs of electrodes 7053 by the above method. The microcomputer further derives the soot accumulation amount in the CSF 503B based on the detected combined capacity (step S005).

  If the accumulation amount of soot derived in step S005 is equal to or greater than the soot threshold (YES in step S007), the microcomputer performs forced regeneration of CSF 503B and sensor unit 705 to burn the soot deposited on CSF 503B and sensor unit 705. (Step S009). In step S009, for example, the temperature of the exhaust gas may be set to about 500 ° C. or higher at which soot burns by post injection.

  On the other hand, if NO is determined in step S007 or if step S009 ends, the microcomputer returns to step S001.

  If YES is determined in step S003, the microcomputer waits for a predetermined time (YES in step S011), and then performs the same processing as in steps S001 and S003 again to determine the current exhaust gas. It is determined whether or not the temperature is equal to or lower than the temperature threshold (steps S013 and S015).

  If it is determined NO in step S015, the microcomputer regards the SOF as combusted due to the temperature rise of the exhaust gas, and performs step S005.

  On the other hand, if YES is determined in step S015, the microcomputer obtains a signal corresponding to the temperature of the porous body 7051 from the temperature sensor 709 and derives the current temperature of the porous body 7051 (step S017). .

  Next, the microcomputer starts power supply to the heating element 707 based on feedback control such as PID control so that the temperature of the porous body 7051 varies approximately around the first temperature (step S019). As a result, the heating element 707 starts heating the porous body 7051. Here, the first temperature is designed to be equal to or higher than the combustion temperature (oxidation temperature) of SOF and lower than the temperature at which soot does not burn. As such 1st temperature, it is 300 to 400 degreeC in general, for example.

  Next, the microcomputer detects the combined capacitance of the electrode 7053 by the same method as in step S005, and holds the detected value as an initial value of the combined capacitance (step S021).

  Next, when a predetermined composite capacitance detection cycle has elapsed (step S023), the microcomputer detects and holds the composite capacitance of the electrode 7053 again by the same method as in step S021 (step S025).

  Next, the microcomputer determines whether or not n or more combined capacitance values are held (step S027). Here, n is a natural number of 2 or more.

If NO is determined in step S027, the microcomputer returns to step S023.
On the other hand, if YES is determined, the microcomputer determines whether or not the change in the n synthesized capacitance values has been substantially constant (step S029).

  In step S029, for example, the following processing is performed. The average value of the last n composite capacitance values is calculated. Thereafter, the average value is subtracted from each of the n composite capacitance values, and n difference values are calculated. If the absolute value of the n difference values is less than or equal to the predetermined reference value, YES is determined in step S029. The predetermined reference value is preferably as close to zero as possible.

If NO is determined in step S029, the microcomputer returns to step S023.
If YES is determined in step S029, the microcomputer considers that all of the SOF of the porous body 7051 has been burned, and ends the power supply to the heating element 707 (step S031).

  During steps S019 to S031 in FIG. 4, the temperature of the porous body 7051 is kept constant. In step S021, the initial value of the combined capacity is detected and held. In step S029, the combined capacity of the SOF after complete combustion is detected and held.

  Under the condition that the temperature of the porous body 7051 is constant, the difference value of the synthetic capacity after the SOF combustion from the initial value of the synthetic capacity correlates with the amount of SOF deposited. The correlation at the first temperature is derived in advance at the design and development stage of the SOF amount calculation apparatus 1, and a table indicating the SOF deposition amount for each difference value is held in the program memory.

  As shown in FIG. 4, after step S031, the microcomputer obtains the difference value of the composite capacity obtained in step S029 from the initial value of the composite capacity obtained in step S021 (step S033), and the difference obtained in step S033. The SOF deposition amount corresponding to the value is derived from the table (step S035). Based on the SOF accumulation amount derived in this way, white smoke countermeasures similar to those in the past are taken.

  When step S035 ends, the microcomputer performs step S005.

<3. Action / Effect of SOF Quantity Calculation Device 1>
In Patent Document 1, the SOF amount is calculated based on the engine speed and the fuel injection amount. However, for example, SOF is likely to occur during low load operation of the vehicle V, but it is difficult to obtain a highly accurate SOF amount during low load operation or the like from a combination of the engine speed and the fuel injection amount.

  On the other hand, as described above, the SOF amount calculating apparatus 1 calculates the SOF amount accumulated inside based on the change in the combined capacity of the sensor 7 that can be mounted on the vehicle V. As described above, the SOF amount calculated by the present SOF amount calculation device 1 is based on the combined capacity that varies depending on the actual SOF amount, and is therefore more accurate than the conventional SOF amount calculation device.

  As described above, according to the present disclosure, it is possible to provide the SOF amount calculation apparatus 1 that can calculate the SOF amount with high accuracy.

  Further, according to the present disclosure, the amount of SOF can be calculated with high accuracy by combining a small sensor 7 that can be attached to the exhaust flow path 501 and a so-called ECU. In other words, according to the present SOF calculation device 1, it is possible to calculate the SOF amount with high accuracy while being mounted on the vehicle V by using it together with the sensor 7.

  In the above embodiment, since the sensor unit 705 is a wall flow type, PM deposited on the porous body 7051 can be prevented from being affected by thermophoresis even if the above-described power supply is performed.

<4. Addendum>
In the above embodiment, when the exhaust gas temperature is equal to or lower than the temperature threshold, the microcomputer supplies power to the heating element 707 so that the temperature of the porous body 7051 (that is, the PM deposit portion) becomes the first temperature. I was in control. However, the present invention is not limited to this, and the microcomputer controls the power supply to the heating element 707 so that the temperature of the porous body 7051 (that is, the PM depositing portion) is always the first temperature regardless of the exhaust gas temperature. May be. Here, depending on the material of the porous body 7051, the capacitor has positive temperature characteristics (or negative temperature characteristics). However, since the temperature of the porous body 7051 is always kept constant, the temperature characteristics of the capacitor can be compensated, and thus the microcomputer can derive a highly accurate composite capacitance value.

  In the above embodiment, in the porous body 7051, the cells C1 and C2 are arranged in a matrix in the height direction T and the width direction W in a plan view from the length direction L. The porous body 7051 is provided with a plurality of heating elements 707A and 707B. Based on this premise, if it is known in advance at the design and development stage of the SOF amount calculation device 1 that there is a distribution in the PM accumulation amount in the plurality of cells C2, it is correlated with the distribution of the PM accumulation amount. In addition, the power supplied to the heating elements 707A and 707B may be individually controlled. More specifically, the amount of power supplied to the heating elements 707A and 707B may be controlled, or the voltage applied to the heating elements 707A and 707B may be controlled.

  In the present disclosure, as a preferred example, the microcomputer acquires a signal indicating the surface temperature of the porous body 7051 from the temperature sensor 709 in step S017. However, the present invention is not limited to this, and the temperature of the porous body 7051 may be estimated based on a signal from a temperature sensor provided at another location.

  As is well known, as a model for soot formation and oxidation, there is a soot model described in SAE paper 930612 (title “Approach to Low Nox and Smoke Emissions Engineering by Using Phenomenological Simulation”). The soot model may be corrected using the combined capacity obtained in the above embodiment.

  The SOF amount calculation device of the present disclosure can calculate the SOF amount with high accuracy, and is suitable for a passenger car, a commercial vehicle, or the like equipped with an internal combustion engine such as a diesel engine or a gasoline engine.

DESCRIPTION OF SYMBOLS 1 SOF amount calculation apparatus 3 Internal combustion engine 5 Exhaust system 501 Exhaust flow path 503B CSF
7 Sensor 705 Sensor part 7501 Porous body (deposition part)
7503 Electrode 707 Heating element 709 Temperature sensor

Claims (6)

At least one deposition part made of a porous material and on which the particulate matter contained in the exhaust gas is deposited, at least a pair of electrodes facing each other across the at least one deposition part, and the at least one deposition An SOF amount calculating device connected to a sensor including a heating element that heats the unit,
A temperature acquisition unit for acquiring a signal according to the temperature of the at least one deposition unit;
Based on the signal acquired by the temperature acquisition unit, power is supplied to the heating element so as to heat the deposition unit at a first temperature at which soluble organic components contained in the particulate matter can be combusted but soot does not combust. A power supply to control;
Based on the time from the start of power supply to the heating element until the capacitance between the pair of electrodes becomes substantially constant, and the amount of change in capacitance between the pair of electrodes, A SOF amount calculating apparatus comprising: a first deriving unit that derives the amount of the soluble organic component.   If the temperature of the exhaust gas is equal to or lower than a temperature threshold at which the soluble organic component burns, the power supply unit supplies the heating element with the temperature of the at least one deposition unit maintained at the first temperature. The SOF amount calculating apparatus according to claim 1, wherein the power supply of the SOF is controlled.   2. The SOF amount calculation device according to claim 1, wherein the power supply unit controls power supply to the heating element such that a temperature of the at least one deposition unit is constantly maintained at the first temperature. The at least one deposition part is a plurality of deposition parts arranged in a predetermined direction,
The at least one heating element is a plurality of heating elements provided at different positions in the plurality of deposition portions,
2. The SOF amount calculation device according to claim 1, wherein the power supply unit individually controls the temperatures of the plurality of heating elements based on a distribution of a deposition amount of particulate matter in the plurality of deposition units.   The SOF amount calculation device according to claim 1, further comprising: a second derivation unit that derives the amount of soot accumulated in the deposition unit based on a capacitance between the pair of electrodes.   The SOF amount calculating apparatus according to claim 1, wherein the at least one deposition portion is a wall flow type.

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