JP2012219674A - Particulate-matter processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve proper timing for regenerating an electrode.SOLUTION: A particulate-matter processing device includes: an electrode provided in an exhaust passage of an internal combustion engine; a power supply connected to the electrode in order to apply a voltage thereto; a detection device for detecting a current flowing through the electrode; an applied-voltage lower-limit-value detecting device that detects an applied voltage which becomes the boundary for determining whether or not a current is detected by the detection device when a voltage is applied to the electrode; an applied-voltage lower-limit-value learning device that learns the applied voltage to be detected by the applied-voltage lower-limit-value detecting device; a regeneration device for performing regeneration of the electrode; and a regeneration timing determining device that allows the regeneration device to perform regeneration of the electrode when the applied voltage to be learned by the applied-voltage lower-limit-value learning device is smaller than the applied voltage, learned by the applied-voltage lower-limit-value learning device in the past, by a prescribed amount.

Description

  The present invention relates to a particulate matter processing apparatus.

  A technique is known in which a discharge electrode is provided in an exhaust passage of an internal combustion engine, and corona discharge is generated from the discharge electrode to charge particulate matter (hereinafter also referred to as PM) to agglomerate PM (for example, (See Patent Document 1). By aggregating PM, the number of PM particles can be reduced. Moreover, since the particle diameter of PM becomes large, when a filter is provided on the downstream side, PM is easily collected by the filter.

  Further, a technique is known in which when the current passing through the discharge electrode is equal to or greater than a predetermined value, it is determined that PM is attached to the discharge electrode, and the applied voltage is increased in order to remove PM from the discharge electrode ( For example, see Patent Document 2.) The removal of deposits from the electrode is called electrode regeneration.

  In addition, an insulator is provided between the electrode and the housing to which the electrode is attached, so that an electric current does not flow, and an average of a predetermined period when an inspection voltage about a fraction of the voltage for corona discharge is applied to the electrode A technique is known in which when the current is greater than or equal to a predetermined value, it is determined that PM adheres to the insulator and the insulation performance is degraded (see, for example, Patent Document 3).

  However, even if the applied voltage is lower than that at which corona discharge occurs, if it reaches a certain level, a current passes through a substance such as PM contained in the exhaust gas. For this reason, it is difficult to determine whether the detected current passes through the electrode deposits or the PM floating in the exhaust gas. Conventionally, the current passing through the PM floating in the exhaust gas has not been considered. Therefore, if it is determined whether to regenerate the electrode based on the current passing through the electrode, the determination accuracy may be lowered.

JP 2006-194116 A JP 2006-105081 A Japanese Patent Laid-Open No. 06-173635

  The present invention has been made in view of the above-described problems, and an object thereof is to optimize the timing of electrode regeneration.

In order to achieve the above object, the particulate matter processing apparatus according to the present invention is:
An electrode provided in an exhaust passage of the internal combustion engine;
A power source connected to the electrode for applying a voltage;
A detection device for detecting a current through the electrode;
An applied voltage lower limit value detecting device for detecting an applied voltage serving as a boundary as to whether or not a current is detected by the detecting device when a voltage is applied to the electrode by the power source;
An applied voltage lower limit value learning device for learning an applied voltage detected by the applied voltage lower limit value detection device;
A regenerator that regenerates the electrode, which is a process for removing deposits on the electrode;
When the applied voltage learned by the applied voltage lower limit value learning device is smaller by a predetermined amount than the applied voltage learned by the applied voltage lower limit value learning device in the past, a regeneration time for regenerating the electrode by the regeneration device A determination device;
Is provided.

  Here, when voltage is applied to the electrodes, PM can be charged. The charged PM moves toward the inner wall of the exhaust passage due to the Coulomb force or the flow of exhaust. Since the PM that has reached the inner wall of the exhaust passage emits electrons to the exhaust passage, electricity flows to the ground side from the electrode. And since PM which emitted the electron aggregates with other PM which exists near, the number of particles can be decreased.

  By the way, when the voltage applied to the electrode is too small, the PM is not charged, so that the PM is not aggregated. For this reason, if the applied voltage is too small, current hardly passes. Therefore, in order to agglomerate PM, it is necessary to apply a certain large voltage. This applied voltage is an applied voltage through which a current can pass when PM is charged. The applied voltage lower limit value detection device detects an applied voltage (hereinafter also referred to as an applied voltage lower limit value) at the boundary of whether or not a current passes when a voltage is applied. The applied voltage lower limit value may be the maximum value of the applied voltage that does not pass current even when a voltage is applied, or the minimum value of the applied voltage that passes current when a voltage is applied. Moreover, it is good also as an applied voltage when an electric current begins to pass when increasing an applied voltage gradually. By applying a voltage larger than the lower limit value of the applied voltage detected in this way, PM can be aggregated.

  By the way, when a substance such as PM or water adheres to the electrode, electricity easily flows between the electrode and the exhaust passage through the attached substance. That is, the insulating property of the electrode is lowered. As described above, when there are deposits on the electrode, when a voltage is applied to the electrode, PM may not be aggregated even though a current flows through the electrode. When a substance such as PM adheres to the electrode, it becomes difficult to charge the PM floating in the exhaust gas, so that it is difficult to aggregate the PM. Therefore, when deposits such as PM are present on the electrode, the electrode is regenerated as a process for removing the deposits from the electrode. The regeneration of the electrode is performed by a regeneration device.

  The regeneration device oxidizes or evaporates a substance attached to the electrode, for example, by increasing the temperature of the electrode. Further, the temperature of the electrode may be increased and the oxygen concentration in the exhaust gas may be increased. Moreover, you may heat an electrode.

  This regeneration of the electrode is performed when the insulation of the electrode is lowered. Here, when the insulating property of the electrode is lowered, the applied voltage lower limit value detected by the applied voltage lower limit value detecting device is decreased. Therefore, by learning the application voltage lower limit value detected by the application voltage lower limit value detection device, and comparing the application voltage lower limit value learned in the past with the application voltage lower limit value learned at the present time, A decrease in the insulating properties of the electrode can be detected. That is, when the newly learned applied voltage lower limit value is smaller by a predetermined amount than the previously learned applied voltage lower limit value, it can be determined that the insulation of the electrode has decreased. In addition, when the newly learned applied voltage lower limit value is smaller than the applied voltage lower limit value learned in the past, it may be determined that the insulating property of the electrode has decreased. Then, when the electrode is regenerated when the insulating property of the electrode is lowered, the electrode can be regenerated at an appropriate time. The predetermined amount is set as a value having a margin in consideration of, for example, a current detection error. Further, the predetermined amount may be set as an allowable range of a decrease amount of the applied voltage lower limit value. That is, the electrode may be regenerated when the lowering amount of the applied voltage lower limit exceeds the allowable range.

  Further, “learning” may be “memory”. The applied voltage lower limit is hardly affected by the number of PM particles in the exhaust. For this reason, even if the number of PM particles in the exhaust gas is large, it can be determined with high accuracy whether PM or the like is attached to the electrode. Thereby, optimization of the regeneration time of an electrode can be achieved.

  In the present invention, the applied voltage learned by the applied voltage lower limit learning device in the past is an applied voltage learned by the applied voltage lower limit learning device when there is no deposit on the electrode. There may be.

  That is, when there is no deposit on the electrode, the applied voltage lower limit value is detected by the applied voltage lower limit value detection device, and the applied voltage lower limit value is further learned. In addition, when there is no deposit on the electrode, for example, when the particulate matter processing apparatus is new, or when the travel distance from the new is short, it travels a predetermined distance that is considered that PM does not adhere to the electrode. Or even immediately after the particulate matter processing apparatus is replaced. Further, it may be immediately after the electrode is regenerated, or when the travel distance is short after the electrode is regenerated and until a predetermined distance where PM is not attached to the electrode is traveled. .

  If there is no deposit on the electrode, no current passes through the deposit. If the applied voltage lower limit value detected at this time is learned, it can be determined that PM or the like has adhered to the electrode when the applied voltage lower limit value subsequently decreases. That is, if a decrease in the applied voltage lower limit value is detected, it can be easily determined whether or not the electrode needs to be regenerated.

Further, in the present invention, a processing unit provided in the exhaust passage and provided with the electrode;
An insulating part for insulating electricity between the processing part and the exhaust passage;
A grounding unit for grounding the processing unit;
With
The detection device can detect a current at the grounding portion.

  In this case, the detection device detects a current on the potential reference point side of the electrode. Generally, on the power supply side from the electrode, the wiring is longer or thicker than the electrode on the ground side. In addition, charges may be stored on the power supply side of the electrode. Then, if a current is detected on the power supply side of the electrode, even if a strong discharge occurs in the electrode, the current detected by the detection device rises and falls slowly. On the other hand, on the ground side from the electrode, the wiring can be made relatively short and thin. For this reason, an electric current can be detected more correctly. Moreover, it can suppress that electricity flows other than a grounding part by providing an insulating part. For this reason, an electric current can be detected more correctly.

  According to the present invention, it is possible to optimize the regeneration timing of the electrodes.

It is a figure which shows schematic structure of the particulate matter processing apparatus which concerns on an Example. It is the figure which showed the relationship between an applied voltage, pulse electric power, non-pulse electric power, PM particle number, and PM particle number reduction rate. It is the flowchart which showed the determination flow of the electrode regeneration time which concerns on an Example.

  Hereinafter, specific embodiments of the particulate matter processing apparatus according to the present invention will be described with reference to the drawings.

Example 1
FIG. 1 is a diagram illustrating a schematic configuration of a particulate matter processing apparatus 1 according to the present embodiment. The particulate matter processing apparatus 1 is provided in an exhaust passage 2 of a gasoline engine. It can also be provided in the exhaust passage of a diesel engine.

  The particulate matter processing apparatus 1 includes a housing 3 whose both ends are connected to an exhaust passage 2. The material of the housing 3 is a stainless steel material. The housing 3 is formed in a hollow cylindrical shape having a diameter larger than that of the exhaust passage 2. Both ends of the housing 3 are formed in a tapered shape in which the cross-sectional area decreases as the distance from the end increases. In FIG. 1, the exhaust flows through the exhaust passage 2 in the direction of the arrow and flows into the housing 3. For this reason, the housing 3 may be a part of the exhaust passage 2.

  The exhaust passage 2 and the housing 3 are connected via an insulating portion 4. The insulating part 4 is made of an electrical insulator. The insulating portion 4 is sandwiched between a flange 21 formed at the end of the exhaust passage 2 and a flange 31 formed at the end of the housing 3. The exhaust passage 2 and the housing 3 are fastened by bolts and nuts, for example. In addition, these bolts and nuts are also insulated so that electricity does not flow through these bolts and nuts. In this way, electricity is prevented from flowing between the exhaust passage 2 and the housing 3.

  An electrode 5 is attached to the housing 3. The electrode 5 penetrates the side surface of the housing 3, extends from the side surface of the housing 3 toward the central axis of the housing 3, bends in the vicinity of the central axis, and upstream of the flow of exhaust gas, and is parallel to the central axis It extends toward the upstream side of the exhaust flow. Further, it bends further to the side surface side of the housing 3 on the upstream side, passes through the side surface of the housing 3 and communicates with the outside.

  In order to prevent electricity from flowing between the electrode 5 and the housing 3, the electrode 5 is provided with insulator portions 51 and 55 made of an electrical insulator. The insulator portions 51 and 55 are located between the electrode 5 and the housing 3, and have a function of insulating electricity and fixing the electrode 5 to the housing 3.

  One end of the electrode 5 is connected to the power supply 6 via the power supply side electric wire 52. The power source 6 can energize the electrode 5 and change the applied voltage. The power source 6 is connected to the control device 7 and the battery 8 through electric wires. The control device 7 controls the voltage that the power source 6 applies to the electrode 5. The power supply 6 is connected to a ground wire 54 for connection to a potential reference point. The power source 6 is grounded by the ground wire 54.

  The other end of the electrode 5 is connected to the ground wire 54 via a short-circuit wire 56. A switch 57 for opening and closing the circuit is provided in the middle of the short-circuit wire 56. When the switch 57 is turned on while a voltage is applied by the power source 6, electricity flows through the short-circuited wire 56. At this time, since the electrode 5 is short-circuited, the temperature of the electrode 5 rises. In the present embodiment, the short-circuit wire 56 and the switch 57 correspond to the reproducing device in the present invention. Further, in this embodiment, the power supply side electric wire 52 is connected to the downstream side insulator 51 and the short-circuited wire 56 is connected to the upstream side insulator 55, but instead, the downstream side insulator 51 is connected. The short-circuited wire 56 may be connected to the power supply side electric wire 52 and the upstream side insulator portion 55 may be connected.

A ground side electric wire 53 is connected to the housing 3, and the housing 3 is grounded via the ground side electric wire 53. The ground side electric wire 53 is provided with a detection device 9 that detects a current passing through the ground side electric wire 53. For example, the detection device 9 detects a current by measuring a potential difference between both ends of a resistor provided in the middle of the ground-side electric wire 53. The detection device 9 is connected to the control device 7 via an electric wire. Then, the current detected by the detection device 9 is input to the control device 7. In addition, since the electric capacity of the ground side electric wire 53 is smaller than that of the power source side electric wire 52, the response when detecting the current is higher when the detection device 9 is provided in the ground side electric wire 53. However, the detection device 9 may be provided in the power supply side electric wire 52 instead of the ground side electric wire 53.

  Note that an accelerator opening sensor 71, a crank position sensor 72, a temperature sensor 73, and an air flow meter 74 are connected to the control device 7. The accelerator opening sensor 71 outputs an electrical signal corresponding to the amount of depression of the accelerator pedal by the driver of the vehicle on which the internal combustion engine is mounted, and detects the engine load. The crank position sensor 72 detects the engine speed. The temperature sensor 73 detects the temperature of the internal combustion engine by detecting the temperature of the cooling water of the internal combustion engine or the temperature of the lubricating oil. The air flow meter 74 detects the intake air amount of the internal combustion engine.

  In addition, a switch 57 is connected to the control device 7 via an electric wire, and the control device 7 performs an ON-OFF operation of the switch 57. Here, when the voltage is applied from the power source 6 to the electrode 5, the current passes through the short-circuited wire 56 by turning on the switch. On the other hand, when the switch is turned off, no current flows through the short-circuited wire 56.

  In the particulate matter processing apparatus 1 configured in this way, electrons are emitted from the electrode 5 by applying a negative high DC voltage from the power source 6 to the electrode 5 when the switch 57 is OFF. That is, electrons are emitted from the electrode 5 by making the potential of the electrode 5 lower than that of the housing 3. The electrons in the exhaust gas can be negatively charged by the electrons. Negatively charged PM moves due to Coulomb force and gas flow. When the PM reaches the housing 3, the electrons that have negatively charged the PM are emitted to the housing 3. The PM that has released electrons to the housing 3 aggregates to increase the particle size. Moreover, the number of PM particles is reduced due to aggregation of PM. That is, by applying a voltage to the electrode 5, the particle diameter of PM can be increased and the number of PM particles can be reduced.

  By the way, when a substance such as PM or water adheres to the electrode 5 including the insulator portion 51, the insulating property of the electrode 5 is lowered. And electricity can flow between the electrode 5 and the housing 3 through these deposits. Then, since electrons emitted from the electrode 5 are reduced, it is difficult to charge the PM floating in the exhaust gas, and it is difficult to aggregate the PM. For this reason, the regeneration process of the electrode 5 is implemented.

  Here, the regeneration process of the electrode 5 is a process for removing deposits such as PM and water adhering to the electrode 5 including the insulator parts 51 and 55. In this embodiment, the electrode 5 is regenerated by applying a voltage from the power source 6 while turning on the switch 57. That is, by short-circuiting the electrode 5, the temperature of the electrode 5 is raised and the deposits are removed by burning or evaporation. In order to oxidize PM quickly, it is better that the oxygen concentration in the exhaust gas is high. Therefore, the oxygen concentration in the exhaust gas may be increased before the electrode 5 is short-circuited or when the electrode 5 is short-circuited. In order to increase the oxygen concentration in the exhaust gas, for example, in a hybrid vehicle including an internal combustion engine and a motor as a vehicle drive source, the crankshaft of the internal combustion engine may be rotated by the motor without supplying fuel to the internal combustion engine. Good. Thereby, since air can be discharged | emitted from an internal combustion engine, the oxygen concentration in exhaust_gas | exhaustion can be raised. Further, by temporarily increasing the engine speed before stopping the internal combustion engine and stopping the fuel supply when the engine speed is high, air can be discharged into the exhaust passage. Then, the electrode 5 may be short-circuited when the internal combustion engine stops thereafter. Further, at the time of fuel cut during the deceleration operation, the oxygen concentration in the exhaust gas becomes high. Therefore, the electrode 5 may be short-circuited at this time.

The regeneration of the electrode 5 is performed when it is determined that the insulating property of the electrode 5 has decreased. That the insulating property of the electrode 5 has decreased is determined based on the minimum value of the applied voltage through which the current passes. Here, if the voltage applied from the power source 6 to the electrode 5 is too small, the number of PM particles may not change even when a voltage is applied. That is, there is an applied voltage (hereinafter referred to as a reactive voltage) in which PM hardly aggregates. For this reason, if the applied voltage is within the reactive voltage range, the number of PM particles does not change, and no current is detected by the detection device 9.

  Here, FIG. 2 is a diagram showing the relationship among applied voltage, pulse power, non-pulse power, PM particle number, and PM particle number reduction rate. This relationship varies depending on the engine speed, the engine load, the temperature of the internal combustion engine, and the like. Here, the pulse power is power when a pulse current is generated. This pulse current is detected when a strong discharge such as a corona discharge is occurring. Non-pulse power is power when no pulse current is generated. The number of PM particles is the number of PM particles per cubic centimeter in the exhaust. The PM particle number reduction rate is a value indicating the degree of reduction in the number of PM particles, and is obtained by subtracting “the number of PM particles flowing out of the housing 3” from the “number of PM particles flowing into the housing 3”. This is a value obtained by dividing the amount of decrease in the number of particles by “the number of PM particles flowing into the housing 3”.

  As shown in FIG. 2, the pulse power and the non-pulse power are 0 (W) when the applied voltage is from 0 to A. That is, almost no current flows. For this reason, there is almost no change in the number of PM particles and the PM particle number reduction rate. Therefore, in FIG. 2, the applied voltage from 0 to A corresponds to the reactive voltage. Since the reactive voltage has a large individual difference, it is necessary to obtain it for each particulate matter processing apparatus.

  In the present embodiment, when a voltage is applied to the electrode 5 by the power source 6, an applied voltage (that is, an applied voltage lower limit value) that becomes a boundary of whether or not a current is detected by the detection device 9 is detected and learned. This may be to detect and learn the applied voltage at which current begins to flow. Further, the maximum value of the reactive voltage or the minimum value of the applied voltage through which the current passes may be detected and learned.

  The lower limit value of the applied voltage becomes smaller when PM or the like adheres to the electrode 5. That is, since the current passes through the deposit such as PM, the current starts to pass at a lower applied voltage. Therefore, when the lower limit value of the applied voltage is lowered, the electrode 5 is regenerated. When there is no deposit on the electrode 5, the lower limit value of the applied voltage is a substantially constant value regardless of the number of PM particles in the exhaust gas. Therefore, when determining whether or not the electrode 5 needs to be regenerated, the influence of the current passing through the PM floating in the exhaust gas can be ignored.

  Next, FIG. 3 is a flowchart showing a determination flow of electrode regeneration timing according to the present embodiment. This routine is repeatedly executed by the control device 7 every predetermined time.

In step S101, the voltage applied to the electrode 5 is calculated. The applied voltage is set according to the estimated number of PM particles (number / cm ³ ). The number of PM particles is the number of PM particles discharged from the internal combustion engine, and is the number of PM particles before flowing into the housing 3. Since the number of PM particles is correlated with the engine speed, the engine load, and the temperature of the internal combustion engine (for example, the temperature of the lubricating oil or the temperature of the cooling water), the number of PM particles is calculated based on these values. A plurality of maps for calculating the number of PM particles may be stored according to the temperature of the internal combustion engine from the engine speed and the engine load, and the number of PM particles may be calculated based on the map.

  The engine speed is detected by a crank position sensor 72, and the engine load is detected by an accelerator opening sensor 71. The temperature of the internal combustion engine is detected by a temperature sensor 73. Alternatively, a sensor for detecting the number of PM particles may be attached to the exhaust passage 2 upstream of the housing 3 and the number of PM particles may be detected by the sensor.

Then, the applied voltage is calculated based on the number of PM particles and the exhaust gas amount (g / sec) of the internal combustion engine. This relationship may be obtained in advance by experiments or the like and mapped. Since the exhaust gas amount of the internal combustion engine has a correlation with the intake air amount of the internal combustion engine, it can be obtained based on the intake air amount detected by the air flow meter 74.

  Here, since the inertia force of PM becomes smaller as the amount of exhaust gas is smaller, the influence of electrostatic action becomes relatively larger. For this reason, PM tends to aggregate. Therefore, as the amount of exhaust gas decreases, PM aggregates with a smaller applied voltage. For this reason, the applied voltage is reduced as the amount of exhaust gas decreases. Also, the greater the number of PM particles, the shorter the distance between the PM particles, so that the influence of electrostatic action becomes relatively large. Therefore, as the number of PM particles increases, PM aggregates with a smaller applied voltage. For this reason, the applied voltage is decreased as the number of PM particles is increased. Further, the applied voltage may be a value such that the reduction rate of the number of PM particles becomes a predetermined value (for example, 40%). The applied voltage may be a predetermined value that is determined in advance. In this case, the minimum applied voltage that can detect the HC concentration may be used. That is, the applied voltage may be made smaller than when aggregating PM.

  Then, after the applied voltage is calculated, the applied voltage is applied to the electrode 5 and the process proceeds to step S102. In step S102, a current is detected by the detection device 9.

  In step S103, it is determined whether or not it is time to determine whether or not to perform the regeneration processing of the electrode 5. For example, the determination is made based on whether or not the integrated value of the operating time of the internal combustion engine since the determination as to whether or not the regeneration process of the electrode 5 is performed last time has reached a predetermined value. In this case, every time the integrated value of the operation time reaches a predetermined value, it is determined whether or not the regeneration process of the electrode 5 is performed. For example, when the integrated operation time of the internal combustion engine is a multiple of a predetermined value, it may be determined that it is time to make the above determination. Further, when the travel distance of the vehicle equipped with the internal combustion engine is a multiple of a predetermined value, it may be determined that it is time to make the above determination. These predetermined values are obtained by experiments or the like as values that allow PM or the like to adhere to the electrode 5. If an affirmative determination is made in step S103, the process proceeds to step S104. If a negative determination is made, this routine is terminated.

  In step S104, the applied voltage is set to 0 (V). That is, no voltage is applied to the electrode 5. In this routine, the applied voltage is gradually increased from 0 (V), and it is determined that the applied voltage has become larger than the reactive voltage when the detected current becomes larger than the threshold value. For this reason, in step S104, it is in the state before increasing the applied voltage. If a negative determination is made in step S103, the applied voltage calculated in step S101 is applied to the electrode 5.

  In step S105, the applied voltage is increased. The increase amount of the applied voltage at this time is set in advance as a value suitable for detecting the applied voltage lower limit value. In other words, if the increase amount of the applied voltage is too small, it takes time because the voltage must be increased many times before the current increases. On the other hand, if the increase amount of the applied voltage is too large, the time until the current increases can be shortened, but it is difficult to accurately obtain the lower limit value of the applied voltage. Therefore, the increase amount of the applied voltage may be determined based on the required time and the required accuracy.

  In step S106, a detected current is acquired. This detected current is a current detected by the detection device 9.

  In step S107, it is determined whether or not the detected current acquired in step S106 is greater than a predetermined value B. In this step, it is determined whether or not a current passes through the electrode 5. That is, it is determined whether or not the applied voltage is greater than the reactive voltage. The predetermined value B is a detection current that is considered not to aggregate PM, and is obtained in advance by experiments or the like.

  If an affirmative determination is made in step S107, the process proceeds to step S108, and if a negative determination is made, the process returns to step S105. In this embodiment, the control device 7 that processes step S104 to step S107 corresponds to the applied voltage lower limit value detection device in the present invention.

  In step S108, the current applied voltage is stored as the applied voltage lower limit value V1. That is, an applied voltage that is a boundary on whether or not a current is detected by the detection device 9 when a voltage is applied to the electrode 5 is learned. In this embodiment, the control device 7 for processing step S108 corresponds to the applied voltage lower limit value learning device in the present invention.

  In step S109, the applied voltage lower limit value V1 learned in step S108 is a value obtained by subtracting a predetermined value C from the reference value V0 of the applied voltage lower limit value learned in the past (hereinafter referred to as the reference applied voltage lower limit value V0). Or less is determined.

  Here, the reference applied voltage lower limit value V0 can be the applied voltage lower limit value when there is almost no deposit on the electrode 5. For example, the applied voltage lower limit value learned immediately after the previous regeneration of the electrode 5 can be set as the reference applied voltage lower limit value V0. Further, when the particulate matter treatment apparatus 1 is new, or when the particulate matter treatment apparatus 1 travels a predetermined distance where the travel distance from the new article is short and PM is not attached to the electrode, further, the particulate matter The applied voltage lower limit value learned immediately after replacing the processing apparatus 1 may be set as the reference applied voltage lower limit value V0. In addition, the applied voltage lower limit value learned until the traveling distance is short after the electrode 5 is regenerated and the PM 5 is not attached to the electrode 5 is used as the reference applied voltage lower limit value V0. It is good.

  The predetermined value C is a value for providing a margin for an error in the current detected by the detection device 9. Further, the predetermined value C may be set as an upper limit value of an allowable range of a decrease amount of the applied voltage lower limit value. In this case, when the amount of decrease from the reference applied voltage lower limit value V0 exceeds the predetermined value C, it is determined that the amount of PM or the like adhering to the electrode 5 has exceeded the allowable value.

  If an affirmative determination is made in step S109, the process proceeds to step S110, and if a negative determination is made, regeneration of the electrode 5 is not necessary, and thus this routine is terminated.

  In step S110, the electrode regeneration flag is turned ON. The electrode regeneration flag is a flag that is turned on when the electrode 5 needs to be regenerated and turned off when the electrode 5 is not regenerated. Note that the initial value of the electrode regeneration flag is OFF. When the electrode regeneration flag is turned ON, the regeneration process of the electrode 5 is performed in the operation state suitable for the regeneration of the electrode 5. In this embodiment, the control device 7 that processes step S109 and step S110 corresponds to the regeneration timing determination device in the present invention.

  In this manner, it is possible to determine whether or not the electrode 5 needs to be regenerated by learning the lower limit value of the applied voltage that can aggregate PM. Thereby, since the regeneration time of the electrode 5 can be optimized, the aggregation of PM can be promoted. Moreover, since it can suppress that regeneration of the electrode 5 is performed more than necessary, energy consumption can be reduced, so that deterioration of fuel consumption can be suppressed.

DESCRIPTION OF SYMBOLS 1 Particulate matter processing apparatus 2 Exhaust passage 3 Housing 4 Insulation part 5 Electrode 6 Power supply 7 Control apparatus 8 Battery 9 Detection apparatus 21 Flange 31 Flange 51 Insulator part 52 Power supply side electric wire 53 Ground side electric wire 54 Ground electric wire 55 Insulator part 56 Short circuit electric wire 57 Switch 71 Accelerator opening sensor 72 Crank position sensor 73 Temperature sensor 74 Air flow meter

Claims (3)

An electrode provided in an exhaust passage of the internal combustion engine;
A power source connected to the electrode for applying a voltage;
A detection device for detecting a current through the electrode;
An applied voltage lower limit value detecting device for detecting an applied voltage serving as a boundary as to whether or not a current is detected by the detecting device when a voltage is applied to the electrode by the power source;
An applied voltage lower limit value learning device for learning an applied voltage detected by the applied voltage lower limit value detection device;
A regenerator that regenerates the electrode, which is a process for removing deposits on the electrode;
When the applied voltage learned by the applied voltage lower limit value learning device is smaller by a predetermined amount than the applied voltage learned by the applied voltage lower limit value learning device in the past, a regeneration time for regenerating the electrode by the regeneration device A determination device;
A particulate matter processing apparatus comprising:   2. The applied voltage learned by the applied voltage lower limit learning device in the past is an applied voltage learned by the applied voltage lower limit learning device when no deposit is present on the electrode. Particulate matter treatment equipment. A processing section provided in the exhaust passage and provided with the electrode;
An insulating part for insulating electricity between the processing part and the exhaust passage;
A grounding unit for grounding the processing unit;
With
The particulate matter processing apparatus according to claim 1, wherein the detection device detects a current at the grounding unit.

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