JP2012219770A - Particulate-matter processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a failure in a particulate-matter processing device.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; a deposited-matter determining device for determining whether or not deposited matter deposited on the electrode is present; and a failure determination device that determines the presence of a failure if the current to be detected by the detection device when determined by the deposited-matter determining device that deposited matter is not present on the electrode is larger than the threshold.

Description

  The present invention relates to a particulate matter processing apparatus.

  When the current passing through the discharge electrode is equal to or greater than a predetermined value, it is determined that particulate matter (hereinafter also referred to as PM) is attached to the discharge electrode, and the applied voltage is increased to remove PM from the discharge electrode. The technique to make is known (for example, refer patent document 1). The removal of deposits from the electrode is called electrode regeneration.

  In addition, a technique for determining a failure of the PM sensor based on a change in capacitance of the sensor electrode part due to the condensed water generated in the exhaust pipe immediately after the engine starts adheres to the sensor electrode part is known ( For example, see Patent Document 2.)

  In addition, 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 the PM to aggregate the PM (see, for example, Patent Document 3). 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.

  By the way, besides water and PM adhering to the electrode, the particulate matter processing apparatus may be broken down or deteriorated. In such a case, it may be difficult to aggregate PM even if the electrode is regenerated. Therefore, it is also important to detect a failure.

JP 2006-105081 A JP 2010-275917 A JP 2006-194116 A

  The present invention has been made in view of the above-described problems, and an object thereof is to detect a failure of a particulate matter processing apparatus.

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 adhering matter judgment device for judging whether or not there is an adhering matter adhering to the electrode;
A failure determination device that determines that a failure has occurred when the current detected by the detection device is greater than a threshold when it is determined by the attachment determination device that no deposit is present on the electrode;
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, if deposits such as water and PM are present on the electrode, electricity flows between the electrode and the exhaust passage through the deposits, so it becomes difficult to charge PM floating in the exhaust. . For this reason, it becomes difficult to aggregate PM. On the other hand, when electricity flows between the electrode and the exhaust passage through the electrode deposit, the current detected by the detection device increases. And the electric current which passes through the deposit | attachment of an electrode is larger than the electric current which passes when coagulating PM which is floating in exhaust_gas | exhaustion.

  In addition, the current detected by the detection device may increase due to a failure of the particulate matter processing device (for example, short circuit of the electrode, damage or deformation of the device). If there is any deposit on the electrode, the detected current will be small if the deposit is removed. However, in the case of the above failure, the detection is performed regardless of whether the deposit is present. Current is increased. For this reason, when the deposit exists on the electrode, it is necessary to determine whether the current is increased due to the deposit or whether the current is increased due to a failure. On the other hand, when there is no deposit on the electrode and the current is large, it can be determined that the device has failed. Here, when the detected current is larger than the threshold value, the threshold value is set to the upper limit value of the current detected when there is no deposit on the electrode and the particulate matter processing apparatus is normal. It can be determined that a failure has occurred.

  In addition, if water or PM adheres to the electrode or the above-described failure occurs, the electrical resistance decreases. This electrical resistance can be calculated based on the applied voltage and the detected current. And failure determination can also be performed based on the calculated electrical resistance. In this case, the detected electric resistance is smaller than the threshold value by setting the threshold value as the lower limit value of the electric resistance detected when there is no deposit on the electrode and the particulate matter processing apparatus is normal. Sometimes it can be determined that a failure has occurred.

  In the present invention, the threshold value is determined before the deposit determining device determines that there is no deposit on the electrode and when the deposit determining device determines that the deposit is present on the electrode. You may set based on the electric current detected by the said detection apparatus.

  Here, if the particulate matter processing apparatus is normal, the deposits are removed from the electrode, so that the current passing through the electrode becomes small. That is, the current detected when there is no deposit on the electrode is smaller than the current detected when the deposit is present on the electrode. Therefore, when there is almost no difference between the current detected when the deposit is present on the electrode and the current detected when the deposit is not present on the electrode, it can be determined that there is a failure. That is, the failure can be determined by comparing the current before and after the deposit is removed. Note that the current detected when it is determined by the adhering matter determination device that the adhering matter is present on the electrode may be used as a threshold value, or a value obtained by subtracting an allowance in consideration of detection error or the like may be used as the threshold value. . In this way, by considering the state before it is determined that there is no deposit on the electrode, it becomes difficult to be affected by individual differences between devices and aging, so that the accuracy of failure determination can be further increased.

  In the present invention, the attached matter determination device can determine whether water is present as an attached matter.

Here, when water adheres to the electrode, electricity flows through the water. The water adhering to the electrode is a condensed water in the exhaust. Therefore, it may be determined that water is attached to the electrode when in an operation state where condensed water can be generated. Even if water adheres to the electrode, if the temperature of the exhaust passage or the electrode subsequently increases, the water evaporates from the electrode. For example, when the internal combustion engine is started, water may adhere to the electrodes, and it may be determined that water is removed from the electrodes when a predetermined time has elapsed since the internal combustion engine was started.

  In the present invention, the adhering matter determination device can determine whether or not particulate matter exists as the adhering matter.

  Here, when particulate matter (PM) adheres to the electrode, electricity flows through the PM. The PM adhering to the electrode is discharged from the internal combustion engine. Therefore, for example, when the total amount of PM discharged from the internal combustion engine is greater than or equal to a predetermined amount, it may be determined that PM is attached to the electrode. In addition, even if PM adheres to the electrode, PM is removed from the electrode by regenerating the electrode thereafter. Here, the regeneration of the electrode is a process for removing deposits such as PM adhering to the electrode. For example, by short-circuiting the electrode, the temperature of the electrode is raised to oxidize and remove PM. If it is immediately after regeneration of this electrode, it will be determined that there is no deposit on the electrode.

  According to the present invention, it is possible to detect a failure of the particulate matter processing apparatus.

It is a figure which shows schematic structure of the particulate matter processing apparatus which concerns on an Example. 3 is a flowchart illustrating a flow of failure determination according to the first embodiment. 10 is a flowchart illustrating a flow of failure determination according to the second embodiment.

  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. 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.

  In this embodiment, the failure of the particulate matter processing device 1 is determined based on the current detected by the detection device 9. For example, when the housing 3 or the electrode 5 is damaged or deformed, the current passing through the circuit may increase. A case where such a large current passes is determined as a failure of the particulate matter processing apparatus 1.

  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. That is, as in the case where the particulate matter processing device 1 is out of order, the current detected by the detection device 9 increases. Such deposits on the electrode 5 may be able to be removed. In such a case, it is not necessary to determine that there is a failure. Therefore, in this embodiment, the failure determination is performed based on the detected current when there is no deposit on the electrode 5. Thereby, since it becomes difficult to receive the influence of the deposit | attachment of the electrode 5, the precision of failure detection determination can be improved.

  Next, FIG. 2 is a flowchart showing a flow of failure determination according to the present embodiment. This routine is repeatedly executed by the control device 7 every predetermined time. In this routine, the failure determination is performed by comparing the detected currents when the condensed water adheres to the electrode 5 and when the condensed water evaporates.

  In step S101, the operating state of the internal combustion engine is acquired. For example, values necessary for the subsequent processing, such as engine speed, engine load, and internal combustion engine temperature, are read. The engine speed is detected by a crank position sensor 72, and the engine load is detected by an accelerator opening sensor 71. Further, the temperature sensor 73 detects the temperature of the internal combustion engine (for example, the temperature of the lubricating oil or the temperature of the cooling water).

In step S102, the voltage applied to the electrode 5 is calculated. The applied voltage is set according to, for example, 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.

  A sensor for detecting the number of PM particles may be attached to the exhaust passage 2 on the upstream side 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. Furthermore, the applied voltage may be increased as much as possible within a range where no pulse current is generated.

  Then, after the applied voltage is calculated, this voltage is applied, the process proceeds to step S103, and the detected current is acquired. This detected current is a value detected by the detection device 9.

  In step S104, it is determined whether PM is attached to the electrode 5. Here, if PM adheres to the electrode 5, even after the condensed water evaporates, electricity flows through the PM, so that it is difficult to determine the failure. Therefore, failure determination is performed when PM is not attached to the electrode 5. Here, it takes a certain amount of time from the state in which no PM is attached to the electrode 5 until the PM is attached to the electrode 5 and electricity flows through the PM. For this reason, for example, if the operation time of the internal combustion engine after the regeneration of the electrode 5 is within a predetermined range, it is determined that PM is not attached to the electrode 5. Further, the amount of PM attached to the electrode 5 is estimated, and if the amount of PM is equal to or greater than a predetermined value, it is determined that PM is attached to the electrode 5.

  In this step, it may be determined whether or not the insulation resistance is reduced by PM adhering to the electrode 5. That is, even if PM is adhered to the electrode 5, if the insulation resistance is not lowered, this adhesion of PM can be ignored, so that it may be determined that PM is not adhered to the electrode 5.

  If an affirmative determination is made in step S104, it is difficult to determine a failure, and this routine is terminated. In this case, the electrode 5 may be regenerated. On the other hand, if a negative determination is made in step S104, the process proceeds to step S105.

  In step S105, it is estimated whether condensed water adheres to the electrode 5. For example, it is presumed that the condensed water adheres to the electrode 5 when the condition for generating the condensed water in the exhaust passage 2 is satisfied. Since condensed water is generated when the temperature of the exhaust passage 2 is relatively low, it can be estimated that condensed water is generated when the temperature of the exhaust passage 2 is equal to or lower than a threshold value. This threshold value is obtained in advance by experiments or the like as the upper limit value of the temperature of the exhaust passage 2 where condensed water is generated. Further, it may be estimated that condensed water is generated for a predetermined period from the start of the internal combustion engine. Further, whether or not water is condensed in the exhaust passage 2 is determined by the temperature of the exhaust, the temperature of the outside air, the operating state of the internal combustion engine, and the like, so the conditions for generating the condensed water may be mapped. Moreover, you may estimate whether condensed water is produced | generated by a known technique.

  Further, when condensed water exists in the exhaust passage 2 and the accelerator opening increases and the amount of exhaust gas increases, the condensed water adhering to the wall surface of the exhaust passage 2 scatters and the electrode 5 adheres. As described above, when both the condition that the condensed water exists and the condition that the condensed water reaches the electrode 5 may be established, it may be estimated that the water is attached to the electrode 5. Whether or not water reaches the electrode 5 is estimated based on the intake air amount detected by the air flow meter 74, for example. For example, it is determined that water reaches the electrode 5 when the intake air amount is equal to or greater than a threshold value. In this step, the amount of water adhering to the electrode 5 may be estimated. This amount can be estimated by a known technique based on the operating state of the internal combustion engine. For example, it may be assumed that water of droplets present in the exhaust adheres to the electrode 5 at a predetermined rate.

  Alternatively, the total amount of water adhering to the electrode 5 and the total amount of water evaporating from the electrode 5 may be estimated, and the amount of water adhering to the electrode 5 at the present time may be estimated from these values. These can be estimated by known techniques.

  In step S106, it is determined whether or not it is estimated that condensed water is attached to the electrode 5 in step S105. This may be determined whether water is attached to the electrode 5 or not. That is, if the particulate matter treatment apparatus 1 is normal, it is determined whether or not the current detected by the detection apparatus 9 is in a large state.

  In this step, it may be determined whether or not the insulation resistance is reduced by water adhering to the electrode 5. That is, even if water adheres to the electrode 5, if the insulation resistance is not lowered, the adhesion of this water can be ignored, so that it may be determined that no water adheres to the electrode 5. If an affirmative determination is made in step S106, the process proceeds to step S107. If a negative determination is made, failure determination cannot be performed, and thus this routine is terminated.

  In step S107, the current detected by the detection device 9 is acquired. In this step, a current when water is attached to the electrode 5, that is, a current before water is evaporated is detected. The current acquired in this step is defined as a flooded current I1.

  In step S108, it is determined whether or not the evaporation of water that has adhered to the electrode 5 has been completed. In this step, it is determined whether or not water has been removed from the electrode 5. It may be determined whether or not water is attached to the electrode 5. Since the time required for the water adhering to the electrode 5 to evaporate is, for example, about 5 to 10 seconds, it can be determined that the water has evaporated when a longer time has elapsed. In addition, the maximum amount of water that can adhere to the electrode 5 is obtained in advance by experiments or the like, and when the amount of water evaporated from the electrode 5 exceeds the maximum amount, the water that has adhered to the electrode 5 evaporates. You may determine that you did. Here, the evaporation amount of the water adhering to the electrode 5 is determined by the temperature of the exhaust, the temperature of the outside air, the operating state of the internal combustion engine, and the like. These relationships may be obtained in advance by experiments or the like, or these relationships may be mapped. Further, the evaporation amount of water may be obtained by a known technique. It is considered that the water has been removed from the electrode 5 when the amount of water evaporation has increased sufficiently.

  If an affirmative determination is made in step S108, the process proceeds to step S109, and if a negative determination is made, step S108 is executed again. In the present embodiment, the control device 7 that processes step S106 and step S108 corresponds to the adhering matter determination device of the present invention.

  In step S109, the current detected by the detection device 9 is acquired. In this step, the electric current after the water adhering to the electrode 5 evaporates is detected. The current acquired in this step is referred to as post-evaporation current I2.

  In step S110, it is determined whether or not the post-evaporation current I2 acquired in step S109 is larger than a value obtained by subtracting the predetermined value A from the submerged current I1 acquired in step S107. The predetermined value A is a value for providing a margin for an error in the current detected by the detection device 9. Here, if the particulate matter treatment apparatus 1 is normal, the post-evaporation current I2 is smaller than the flooded current I1. On the other hand, when the particulate matter processing apparatus 1 is out of order, the difference between the flooded current I1 and the post-evaporation current I2 becomes small. Therefore, when the particulate matter processing apparatus 1 is out of order, the post-evaporation current I2 becomes larger than the value obtained by subtracting the predetermined value A from the wet current I1. If an affirmative determination is made in step S110, the process proceeds to step S111. If a negative determination is made, there is no failure and the routine is terminated.

In the present embodiment, “a value obtained by subtracting the predetermined value A from the flooded current I1” corresponds to the threshold value in the present invention. Also, instead of “a value obtained by subtracting the predetermined value A from the flooded current I1”,
A preset threshold value can also be adopted. That is, if a threshold value is set as the upper limit value of the post-evaporation current I2 detected when the particulate matter processing apparatus 1 is normal, a failure can be determined by comparing the threshold value with the post-evaporation current I2.

  In step S111, the failure flag is turned ON. This failure flag is a flag that is turned on when the particulate matter processing apparatus 1 is out of order and is turned off when there is no failure. The initial value of the failure flag is OFF. When the failure flag is set to ON, for example, a warning lamp that informs the vehicle driver that there is a failure is turned on. In this embodiment, the control device 7 that processes step S110 and step S111 corresponds to the failure determination device in the present invention.

  As described above, according to the present embodiment, the particulate matter is obtained by comparing the detection current when water is attached to the electrode 5 and when the water attached to the electrode 5 is evaporated. It can be determined whether or not the processing apparatus 1 has failed.

  In the present embodiment, the current is a comparison target, but instead, the electrical resistance (insulation resistance) of the electrode 5 may be the comparison target. That is, when water adheres to the electrode 5, the electrical resistance decreases, and when water evaporates from the electrode 5, the electrical resistance increases. Therefore, when water adheres to the electrode 5 and when water adheres to the electrode 5 It is possible to determine whether or not the particulate matter processing apparatus 1 is out of order by comparing the electric resistances when evaporated.

(Example 2)
In the present embodiment, it is determined whether or not the particulate matter treatment apparatus 1 has failed by comparing the detected current when PM is attached to the electrode 5 and after the regeneration of the electrode 5. To do. Since other devices are the same as those in the first embodiment, the description thereof is omitted.

  Here, when PM adheres to the electrode 5 and electricity flows between the electrode 5 and the housing 3 through the PM, the detected current is similar to that when the particulate matter processing apparatus 1 is out of order. growing. On the other hand, after the electrode 5 is regenerated, electricity does not flow through the PM adhering to the electrode 5, and if the detected current is large at this time, the particulate matter treatment apparatus 1 fails. Can be determined.

  FIG. 3 is a flowchart illustrating a flow of failure determination according to the present embodiment. This routine is repeatedly executed by the control device 7 every predetermined time. In this routine, the failure determination is performed by comparing the detected currents when PM is attached to the electrode 5 and when PM is removed from the electrode 5. In addition, the same code | symbol is attached | subjected about the step in which the same process as the flow shown in FIG. 2 is made, and description is abbreviate | omitted.

  In step S201, it is determined whether or not condensed water adheres to the electrode 5. Here, if water adheres to the electrode 5, electricity flows through the water, so that failure determination becomes difficult. Therefore, failure determination is performed when condensed water is not attached to the electrode 5. In this step, determination is made in the same manner as in steps S105 and S106.

  In this step, it may be determined whether or not the insulation resistance is reduced by water adhering to the electrode 5. That is, even if water adheres to the electrode 5, if the insulation resistance is not lowered, the adhesion of this water can be ignored, so that it may be determined that no water adheres to the electrode 5.

  If an affirmative determination is made in step S201, it is difficult to determine a failure, and this routine is terminated. On the other hand, if a negative determination is made in step S201, the process proceeds to step S202.

  In step S202, it is estimated whether PM has adhered to the electrode 5. For example, it is estimated that PM has adhered to the electrode 5 when a predetermined operation time has elapsed since the previous regeneration of the electrode 5. Alternatively, the number of PM particles or the amount of PM discharged from the internal combustion engine may be integrated, and when this integrated value is equal to or greater than a threshold value, it may be estimated that PM is attached to the electrode 5. Since the number of PM particles or the amount of PM discharged from the internal combustion engine has a correlation with the operation state of the internal combustion engine (for example, the engine speed and the engine load), these relationships are obtained in advance through experiments and mapped. Also good. Alternatively, it may be estimated that PM is attached to the electrode 5 when the travel distance from the previous regeneration of the electrode 5 is a predetermined distance or more.

  In step S203, it is determined whether or not there is a request for regeneration of the electrode 5. That is, it is determined whether or not the electrode 5 needs to be regenerated. This may be determined whether or not PM is attached to the electrode 5. If it is estimated in step S202 that PM has adhered to the electrode 5, it is determined that there is a regeneration request for the electrode 5.

  In this step, it may be determined whether or not the insulation resistance is reduced by PM adhering to the electrode 5. That is, even if PM adheres to the electrode 5, if the insulation resistance is not lowered, the adhesion of this PM can be ignored, so it may be determined that there is no request for regeneration of the electrode 5. If an affirmative determination is made in step S203, the process proceeds to step S204. If a negative determination is made, failure determination cannot be performed, and thus this routine is terminated.

  In step S204, the current detected by the detection device 9 is acquired. In this step, the current when PM is attached to the electrode 5, that is, the current before the regeneration of the electrode 5 is detected. The current acquired in this step is defined as a pre-reproduction current I3.

  In step S205, the electrode 5 is regenerated. Here, the regeneration of the electrode 5 is a process for removing PM adhering to the electrode 5 including the insulator portions 51 and 55. In this embodiment, the electrode 5 is regenerated by applying a voltage from the power source 6 while the switch 57 is ON. That is, by short-circuiting the electrode 5, the temperature of the electrode 5 is raised and PM is burned and removed. 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.

  In step S206, it is determined whether or not the regeneration of the electrode 5 has been completed. In this step, it is determined whether PM has been removed from the electrode 5. It may be determined whether PM is not attached to the electrode 5. For example, the time until the regeneration of the electrode 5 is completed is obtained in advance by experiments or the like. Then, it is determined that the regeneration of the electrode 5 has been completed when the time from the start of the regeneration of the electrode 5 has reached a predetermined time. If an affirmative determination is made in step S206, the process proceeds to step S207, and if a negative determination is made, the process returns to step S205. In this embodiment, the control device 7 that processes step S203 and step S206 corresponds to the attached matter determination device of the present invention.

  In step S207, the current detected by the detection device 9 is acquired. In this step, the current after the PM adhering to the electrode 5 is removed is detected. The current acquired in this step is referred to as post-reproduction current I4.

  In step S208, it is determined whether the post-reproduction current I4 acquired in step S207 is larger than a value obtained by subtracting the predetermined value B from the pre-reproduction current I3 acquired in step S204. The predetermined value B is a value for providing a margin for an error in the current detected by the detection device 9. Here, if the particulate matter processing apparatus 1 is normal, the post-regeneration current I4 is smaller than the pre-regeneration current I3. On the other hand, when the particulate matter processing apparatus 1 is out of order, the difference between the pre-regeneration current I3 and the post-regeneration current I4 becomes small. Therefore, when the particulate matter processing apparatus 1 is out of order, the post-regeneration current I4 becomes larger than the value obtained by subtracting the predetermined value B from the pre-regeneration current I3. If an affirmative determination is made in step S208, the process proceeds to step S111. If a negative determination is made, there is no failure, and the routine is terminated.

  In the present embodiment, “a value obtained by subtracting the predetermined value B from the pre-reproduction current I3” corresponds to the threshold value in the present invention. In the present embodiment, the control device 7 that processes step S208 and step S111 corresponds to the failure determination device in the present invention. Instead of “a value obtained by subtracting the predetermined value B from the pre-reproduction current I3”, a preset threshold value may be employed. That is, if a threshold is set as the upper limit value of the post-regeneration current I4 detected when the particulate matter processing apparatus 1 is normal, a failure can be determined by comparing the threshold with the post-regeneration current I4.

  As described above, according to the present embodiment, by comparing the detection current between when the PM is attached to the electrode 5 and when the PM attached to the electrode 5 is removed, It can be determined whether or not the material processing apparatus 1 is out of order.

  In the present embodiment, the current is a comparison target, but instead, the electrical resistance (insulation resistance) of the electrode 5 may be the comparison target. That is, when PM adheres to the electrode 5, the electrical resistance decreases, and when PM is removed from the electrode 5, the electrical resistance increases. Therefore, when PM is adhered to the electrode 5, the electrical resistance is adhered to the electrode 5. By comparing the electrical resistance when PM is removed, it can be determined whether or not the particulate matter treatment apparatus 1 has failed.

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 (4)

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 adhering matter judgment device for judging whether or not there is an adhering matter adhering to the electrode;
A failure determination device that determines that a failure has occurred when the current detected by the detection device is greater than a threshold when it is determined by the attachment determination device that no deposit is present on the electrode;
A particulate matter processing apparatus comprising:   The threshold value is detected by the detection device before the adhering matter determination device determines that no adhering material is present on the electrode and when the adhering material determination device determines that the adhering material is present on the electrode. The particulate matter processing device according to claim 1, wherein the particulate matter processing device is set based on a current to be applied.   The particulate matter processing apparatus according to claim 1, wherein the attached matter determination device determines whether water is present as an attached matter.   The particulate matter processing apparatus according to any one of claims 1 to 3, wherein the attached matter determination device determines whether or not particulate matter is present as the attached matter.

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