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WO2016052734A1 - Dispositif de détection de défaut de filtre, et dispositif de détection de matière particulaire - Google Patents

Dispositif de détection de défaut de filtre, et dispositif de détection de matière particulaire Download PDF

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Publication number
WO2016052734A1
WO2016052734A1 PCT/JP2015/078060 JP2015078060W WO2016052734A1 WO 2016052734 A1 WO2016052734 A1 WO 2016052734A1 JP 2015078060 W JP2015078060 W JP 2015078060W WO 2016052734 A1 WO2016052734 A1 WO 2016052734A1
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WIPO (PCT)
Prior art keywords
sensor
output value
value
heating
unit
Prior art date
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Ceased
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PCT/JP2015/078060
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English (en)
Japanese (ja)
Inventor
弘宣 下川
小池　和彦
健介 瀧澤
学 吉留
田村　昌之
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Denso Corp
Original Assignee
Denso Corp
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Publication date
Priority claimed from JP2015184870A external-priority patent/JP6426072B2/ja
Application filed by Denso Corp filed Critical Denso Corp
Priority to EP15845761.4A priority Critical patent/EP3203220B1/fr
Priority to US15/516,163 priority patent/US10578518B2/en
Priority to CN201580053457.1A priority patent/CN107076690B/zh
Publication of WO2016052734A1 publication Critical patent/WO2016052734A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/022—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance

Definitions

  • the present invention relates to a filter failure detection device that collects particulate matter in exhaust gas discharged from an internal combustion engine and a particulate matter detection device that detects the amount of particulate matter in exhaust gas.
  • Patent Document 1 discloses correcting an output value of an electrical resistance type sensor that outputs a value corresponding to the amount of particulate matter in exhaust gas using an exhaust temperature, a sensor temperature, and an exhaust flow rate. Yes. According to this, the amount of particulate matter can be detected with high accuracy without being affected by the temperature and the exhaust flow rate with respect to the output value of the sensor.
  • the output value of the sensor greatly varies depending on the particle diameter of the particulate matter discharged from the internal combustion engine.
  • Patent Document 1 since the particle diameter of the particulate matter is not taken into consideration, variation in output value due to the particle diameter cannot be suppressed.
  • the output value of the sensor may vary. The diagnosis results also vary.
  • the present invention has been made in view of the above-described problem, and can suppress variation in the filter failure diagnosis result due to the particle diameter of the particulate matter, and filter output variation due to the particle diameter. It is an object to provide a particulate matter detection device.
  • a filter failure detection apparatus is provided in an exhaust passage (3) of an internal combustion engine (2), and a filter (4) for collecting particulate matter in exhaust gas;
  • a sensor (5) provided downstream of the filter in the exhaust passage and outputting a value corresponding to the amount of particulate matter in the exhaust gas, and a particle size for estimating an average particle size of the particulate matter in the exhaust gas Estimator (S4 to S8, S24 to S28, S44 to S48, S64 to S69, S85 to S90, S104 to S109, S125 to S130, S144 to S149, S165 to S170, 61), the output value and threshold value of the sensor Failure determination unit (S2, S3, S10 to S12, S22, S23, S30 to S32, S42, S43, S50 to S52, S 2, S63, S71 to S73, S82, S83, S92 to S94, S102, S103, S111 to S113, S122, S123, S132
  • the sensor output value tends to decrease as the average particle size of the particulate matter decreases.
  • the present invention has been made based on the results of this investigation, and estimates the average particle diameter of the particulate matter, and corrects the output value of the sensor (sensor output correction) and corrects the threshold value according to the average particle diameter ( At least one of threshold correction).
  • the output value of the sensor is corrected so that the smaller the average particle size is, the more the amount of particulate matter is, so that the output value when the average particle size is small is the average particle size. Can be close to the output value when.
  • the threshold correction the threshold is corrected so as to be a value indicating that the amount of the particulate matter is smaller as the average particle diameter is smaller. That is, the threshold value is corrected in the same direction as the direction in which the output value of the sensor varies depending on the particle diameter. As a result, the influence of the particle diameter can be suppressed in the comparison between the output value of the sensor and the threshold value.
  • the filter failure determination since at least one of sensor output correction and threshold value correction is performed and then the filter failure determination is performed, it is possible to suppress variation in the diagnosis result of the filter failure due to the particle diameter of the particulate matter.
  • the particulate matter detection device of the present invention includes a sensor (5) provided in the exhaust passage (3) of the internal combustion engine (2) and outputting a value corresponding to the amount of particulate matter in the exhaust gas, A particle size estimation unit (S4 to S8, S44 to S48, S64 to S69, S85 to S90, S144 to S149, S165 to S170, 61) for estimating the average particle size of the particulate matter in the exhaust gas, and the sensor A correction unit (S9, S49, S70, S91, S150, correcting the output value to be a value indicating that the amount of the particulate matter is larger as the average particle size estimated by the particle size estimation unit is smaller. S171).
  • a particle size estimation unit S4 to S8, S44 to S48, S64 to S69, S85 to S90, S144 to S149, S165 to S170, 61
  • the sensor A correction unit S9, S49, S70, S91, S150, correcting the output value to be a value
  • the output value of the sensor is corrected so as to be a value indicating that the amount of the particulate matter is larger as the average particle size is smaller, the output value when the average particle size is small is larger. It can be close to the output value. That is, variation in output value due to particle diameter can be suppressed.
  • FIG. 1 is a configuration diagram of an engine system to which a filter failure detection device and a particulate matter detection device according to the present invention are applied.
  • FIG. It is the figure which showed typically the structure of PM sensor used in FIG.
  • FIG. 2 is a diagram illustrating a state in the vicinity of a pair of counter electrodes in a sensor element in the PM sensor used in FIG. 1, illustrating the principle of PM amount detection by the PM sensor. It is the figure which showed the change of the output of PM sensor with respect to collection time. It is a figure of the experimental result of the relationship between the average particle diameter of PM, and the output of PM sensor. It is a flowchart of the failure determination process which concerns on 1st Embodiment.
  • FIG. 6 is a diagram showing a relationship between an output change rate and an average particle diameter in the first to third embodiments. It is the figure which showed the relationship between an average particle diameter and the correction coefficient of a sensor output. It is a flowchart of the failure determination process which concerns on 2nd Embodiment. It is the figure which showed the relationship between an average particle diameter and the correction coefficient of a threshold value. It is a flowchart of the failure determination process which concerns on 3rd Embodiment. It is a flowchart of the failure determination process which concerns on 4th Embodiment.
  • FIG. 6 is a diagram showing a relationship between an output change rate and an average particle diameter in the first to third embodiments. It is the figure which showed the relationship between an average particle diameter and the correction coefficient of a sensor output. It is a flowchart of the failure determination process which concerns on 2nd Embodiment. It is the figure which showed the relationship between an average particle diameter and the correction coefficient of a threshold value. It is a flowchart of the failure determination process which
  • FIG. 8 is a diagram showing the change in element temperature with respect to the elapsed time from the start of PM collection, and the change in sensor output in the lower part.
  • Heating control of the sensor element used in the fourth to eleventh embodiments and the heating It is a figure explaining the change of the sensor output by control. It is the figure which showed the output change rate of PM sensor with respect to 1st temperature in the equivalent PM average particle diameter.
  • the relationship between the rate of change between the sensor output value E1 at the first temperature at which the SOF evaporates but the soot does not burn, and the sensor output value E2 at the second temperature at which the soot burns, and the average particle diameter of PM FIG. It is a flowchart of the failure determination process which concerns on 5th Embodiment.
  • FIG. 1 is a block diagram of a vehicle engine system 1 to which a filter failure detection apparatus and a particulate matter detection apparatus according to the present invention are applied.
  • the engine system 1 includes a diesel engine 2 (hereinafter simply referred to as an engine) as an internal combustion engine.
  • the engine 2 is provided with an injector that injects fuel into the combustion chamber.
  • the engine 2 generates power for driving the vehicle by the fuel injected from the injector self-igniting in the combustion chamber.
  • a diesel particulate filter (DPF) 4 as a filter of the present invention is installed in the exhaust passage 3 of the engine 2.
  • the DPF 4 is a ceramic filter having a known structure. For example, heat resistant ceramics such as cordierite is formed into a honeycomb structure so that a large number of cells serving as gas flow paths are staggered on the inlet side or the outlet side. Contained and configured. Exhaust gas discharged from the engine 2 flows downstream while passing through the porous partition walls of the DPF 4, and PM (particulate matter, particulate matter) contained in the exhaust gas is collected and gradually accumulated.
  • PM partate matter, particulate matter
  • FIG. 2 is a diagram schematically showing the structure of the PM sensor 5.
  • the PM sensor 5 includes, for example, a metal cylindrical cover 51 (hereinafter referred to as a cover 51) whose inside is hollow, and a sensor element 52 disposed in the cover 51.
  • a number of holes 511 are formed in the cover 51, and a part of the exhaust gas flowing through the exhaust passage 3 can enter the cover 51 from the holes 511.
  • the cover 51 is formed with a discharge hole 512 for discharging the exhaust gas that has entered the cover 51.
  • FIG. 2 shows an example in which the discharge hole 512 is formed at the tip of the cover 51.
  • the sensor element 52 is composed of an insulating substrate such as ceramics. On one surface of the sensor element 52 (insulator substrate), a pair of opposed electrodes 53 spaced apart from each other and opposed to each other are provided.
  • FIG. 3 is a diagram for explaining the principle of detection of the PM amount by the PM sensor 5 and shows the state of PM adhesion in the vicinity of the pair of counter electrodes 53.
  • the sensor element 52 is connected to a voltage application circuit 55 that applies a predetermined DC voltage between a pair of counter electrodes 53 based on a command from the control unit 6 described later. Part of the PM in the exhaust gas that has entered the cover 51 is collected (attached) to the sensor element 52 due to its own adhesiveness. PM that has not been collected by the sensor element 52 is discharged from the discharge hole 512.
  • each counter electrode 53 is charged positively and negatively, respectively.
  • PM passing through the vicinity of the counter electrode 53 is charged, and collection into the sensor element 52 is promoted.
  • electrostatic collection PM collection on the sensor element 52 by applying a voltage between the counter electrodes 53 is referred to as electrostatic collection.
  • the PM sensor 5 utilizes the fact that the resistance between the counter electrodes 53 changes according to the amount of PM collected by the sensor element 52, and the PM collected by the sensor element 52. Generate output according to quantity. That is, the PM sensor 5 outputs a value corresponding to the resistance value between the counter electrodes 53 as the PM amount. Specifically, when the amount of PM trapped in the sensor element 52 is small, no sensor output is generated (strictly speaking, only an output smaller than a threshold output that can be considered that the sensor output has risen is generated).
  • the soot component contained in the PM is composed of carbon particles and has conductivity, when the amount of trapped PM becomes a certain amount or more, the pair of counter electrodes 53 are electrically connected and the sensor output rises (threshold value). Output more than output).
  • the engine system 1 includes an ammeter 56 (see FIG. 3) that measures the current flowing between the counter electrodes 53, and the measured value of the ammeter 56 becomes the output of the PM sensor 5.
  • a resistance value (voltage) between the pair of counter electrodes 53 may be measured as a value correlated with the current flowing between the counter electrodes 53, and the resistance value may be used as the output of the PM sensor 5.
  • the voltage application circuit 55 and the ammeter 56 are provided, for example, in the control unit 6 described later.
  • the sensor element 52 is provided with a heater 54 for heating the sensor element 52.
  • the heater 54 is used, for example, to regenerate the PM sensor 5 by burning and removing PM collected by the sensor element 52.
  • the heater 54 is used for obtaining the average particle diameter of PM in addition to the regeneration of the PM sensor 5 (details will be described later).
  • the heater 54 is provided, for example, on the surface of the sensor element 52 (insulator substrate) where the counter electrode 53 is not provided or inside the sensor element 52.
  • the heater 54 is composed of a heating wire such as platinum (Pt).
  • the sensor element 52 is set to a temperature at which all the components (Soot component, SOF component, etc.) constituting the PM can be burned and removed, specifically, for example, a temperature of 600 ° C. or higher (eg, 700 ° C.).
  • the heater 54 is controlled.
  • the heater 54 is connected to the control unit 6 described later.
  • the sensor element 52 corresponds to the adherend portion in the present invention.
  • the heater 54 corresponds to the heating unit in the present invention.
  • the engine system 1 is provided with various sensors necessary for the operation of the engine 2 in addition to the PM sensor 5. Specifically, for example, a rotational speed sensor 71 for detecting the rotational speed of the engine 2, an accelerator pedal sensor 72 for detecting an operation amount (depression amount) of an accelerator pedal for notifying the vehicle side of a required torque of the driver of the vehicle, etc. Is provided.
  • the engine system 1 includes a control unit 6 that controls the entire engine system 1.
  • the control unit 6 has a normal computer structure, and includes a CPU (not shown) for performing various calculations and a memory 61 for storing various information.
  • the control unit 6 detects the operating state of the engine 2 based on detection signals from the various sensors, for example, calculates the optimal fuel injection amount, injection timing, injection pressure, etc. according to the operating state, Control fuel injection.
  • the control unit 6 also has a function as a sensor control unit that controls the operation of the PM sensor 5 in addition to the control of the engine 2. Specifically, the control unit 6 is connected to the PM sensor 5 and performs electrostatic collection from the voltage application circuit 55 or measures the current flowing between the counter electrodes 53 by the ammeter 56. The control unit 6 controls the operation of the heater 54, and controls the temperature of the heater 54 (the temperature of the sensor element 52) by adjusting the current (energization amount) flowing through the heater 54 and the energization time when the heater 54 is operated. To do.
  • FIG. 4 is a diagram showing a change in the output of the PM sensor 5 with respect to the time (collection time) after the start of electrostatic collection.
  • the one-dot chain line in FIG. 4 indicates the estimated output value Ee of the PM sensor 5 when the DPF 4 is a filter that serves as a criterion for failure determination (hereinafter referred to as a reference failure filter). That is, the lines indicated by (1), (2), and (3) indicate the actual output value of the PM sensor 5.
  • the output value Ee of the PM sensor 5 when the DPF 4 is a reference failure filter is estimated.
  • the estimated output value Ee is used as a threshold value, and based on a comparison between this threshold value (estimated output value Ee) and the actual output value of the PM sensor 5, the presence or absence of a failure of the DPF 4 is determined. Specifically, if the actual output value of the PM sensor 5 is larger than the threshold value (estimated output value Ee), it is determined that the DPF 4 is out of order. If the actual output value is smaller than the threshold value, the DPF 4 is normal. judge.
  • the estimated output value Ee (that is, the predetermined value K) at the timing when the estimated output value Ee reaches the predetermined value K (failure determination timing) is set as a threshold value. If the actual output value of the PM sensor 5 at the failure determination timing is larger than the threshold value K, it is determined that the DPF 4 is malfunctioning. If the actual output value is smaller than the threshold value K, the DPF 4 is normal. Is determined. In the example of FIG. 4, when the actual output value is the lines (1) and (2), the DPF 4 is determined to be faulty, and when the actual output value is the line (3), the DPF 4 is determined to be normal.
  • the processing content up to the above in the failure determination method is the same as the processing described in Japanese Patent No. 5115873.
  • correction processing described later is executed in addition to the above processing. That is, when the output of the PM sensor 5 rises (reference time) (corresponding to the failure determination timing shown in FIG. 4) when the DPF 4 is a reference failure filter. Then, when the time when the output of the PM sensor 5 actually rises (actual time) is earlier than the reference time, it is determined that the DPF 4 has failed, and in the latter case, it is determined that the DPF 4 is normal. means.
  • the output value of the PM sensor 5 varies greatly depending on the particle diameter of PM.
  • the lines (1), (2), and (3) shown in FIG. 4 indicate sensor outputs when the PM amount is the same but the average particle diameter of PM is different.
  • the output value of the PM sensor 5 varies greatly due to the influence of the difference in the average particle diameter even though the PM amount is the same.
  • FIG. 5 shows the experimental results of the relationship between the average particle diameter of PM and the output of the PM sensor 5.
  • Each point in FIG. 5 is when the time (starting time) after the start of electrostatic collection is a predetermined time, that is, when the amount of PM collected by the PM sensor 5 is the same between the points.
  • the output value E1 of the PM sensor 5 is shown.
  • Each point indicated by (1), (2), and (3) in FIG. 5 represents an output value at a predetermined collection time in the lines (1), (2), and (3) shown in FIG. Show.
  • the average particle size used in the first embodiment is TSI Inc. In the particle size distribution of PM measured by the Engineer Exhaust Particle Sizer (EEPS) Spectrometer manufactured by the company, it indicates the median particle size in the number cumulative distribution, that is, the median diameter d50.
  • EEPS Engineer Exhaust Particle Sizer
  • the smaller the average particle diameter of PM the smaller the output value of the PM sensor 5. More specifically, in FIG. 5, the smaller the average particle diameter, the larger the change in the sensor output with respect to the change in the average particle diameter.
  • the sensor output changes with respect to the particle diameter. This is because PM is in an amorphous state with lower crystallinity as the particle size is smaller, and PM (amorphous carbon) in an amorphous state has lower conductivity than PM (graphite carbon) in a graphite state. Conceivable.
  • FIG. 6 shows a flowchart of this failure determination process. The process of FIG. 6 is started at the same time as the engine 2 is started, for example, and thereafter repeatedly executed until the engine 2 is stopped. It is assumed that PM is not yet collected by the PM sensor 5 at the start of the process of FIG.
  • control unit 6 first performs electrostatic collection by applying a voltage between the counter electrodes 53 from the voltage application circuit 55 (see FIG. 3) (S1). Thereby, the PM sensor 5 begins to collect PM in the exhaust gas, and PM collection is started.
  • the output value Ee of the PM sensor 5 when the DPF 4 is the reference failure DPF is estimated (S2). That is, the one-dot chain line of FIG. 4 is estimated.
  • the reference failure DPF in the present embodiment specifically means that the collection rate of the DPF 4 is remarkably lowered due to the failure, and the amount of PM passing through the DPF 4 is determined by self-failure diagnosis (On-board-diagnostics, abbreviated as OBD). ) Is the amount corresponding to the regulation value of DPF.
  • the amount f at each time point (per unit time) of PM passing through the DPF 4 when the DPF 4 is the reference failure DPF is estimated and estimated.
  • An integrated amount B of the PM amount f at each time point is obtained.
  • the amount of PM discharged from the engine 2 based on the operating state of the engine 2 such as the rotational speed and torque (fuel injection amount) of the engine 2, in other words, The amount of PM flowing into the reference failure DPF (inflow PM amount) is estimated.
  • the rotational speed of the engine 2 is obtained from the rotational speed sensor 71.
  • the torque (fuel injection amount) is obtained from the detection value of the accelerator pedal sensor 72, the engine speed, and the like.
  • a map of the inflow PM amount with respect to the operating state (rotation speed, torque, etc.) of the engine 2 is stored in advance in the memory 61 (see FIG. 1). Then, the inflow PM amount corresponding to the current operating state of the engine 2 may be read from the map.
  • estimate the PM collection rate of the reference failure DPF Specifically, for example, a predetermined value ⁇ is used as the PM collection rate of the reference failure DPF. Further, the PM collection rate of the DPF also varies depending on the amount of PM deposited in the DPF (PM deposition amount) and the exhaust flow rate. Therefore, the PM collection rate depends on the PM deposition amount and the exhaust flow rate. ⁇ may be corrected. Note that the PM accumulation amount may be estimated based on, for example, the differential pressure across the DPF 4. The exhaust flow rate may be estimated based on, for example, a fresh air amount detected by an air flow meter (not shown) that detects a fresh air amount sucked into the engine 2. At this time, considering the amount of exhaust gas expansion corresponding to the exhaust temperature detected by the exhaust temperature sensor (not shown) and the amount of exhaust gas compression corresponding to the pressure detected by the pressure sensor (not shown), Estimate the exhaust gas flow rate.
  • the PM amount f (outflow PM amount) per unit time flowing out from the reference failure DPF is obtained.
  • the integrated amount B of the PM amount downstream of the DPF 4 at the current time point (i) is obtained. can get.
  • the amount of PM collected by the PM sensor 5 in the obtained integrated amount B is estimated. Specifically, for example, how much of the PM flowing outside the PM sensor 5 enters the cover 51 from the hole 511 (see FIG. 2), or how much PM of the PM that has entered the cover 51
  • the PM collection rate ⁇ to the PM sensor 5 is estimated in consideration of whether the sensor element 52 is attached to the sensor element 52 or the like.
  • a constant predetermined value may be used regardless of various states such as the exhaust gas flow rate, ⁇ (excess air ratio), the exhaust temperature, the temperature of the sensor element 52, and the like. A value corrected accordingly may be used.
  • the larger the exhaust gas flow rate the more difficult it is for PM to enter the cover 51, and PM that has entered the cover 51 is less likely to adhere to the sensor element 52, and even if it adheres, it is likely to be detached from the sensor element 52.
  • the smaller ⁇ is, that is, the richer the PM concentration becomes, the higher the ratio of PM not collected by the PM sensor 5 becomes. Therefore, for example, the PM collection rate ⁇ is estimated such that the larger the exhaust gas flow rate or the smaller ⁇ , the smaller the value.
  • the PM collection rate ⁇ changes since the permanent thermal power acting on the sensor element 52 changes according to the exhaust temperature or the temperature of the sensor element 52, the PM collection rate ⁇ changes.
  • the PM amount collected by the PM sensor 5 is obtained based on the integrated amount B and the PM collection rate ⁇ . Since the output of the PM sensor 5 increases as the amount of PM increases, the relationship between the amount of PM and the output of the PM sensor 5 is examined in advance and stored in the memory 61. Based on this relationship and the PM amount obtained this time, an estimated value of the output of the PM sensor 5 when the DPF 4 is the reference failure DPF is obtained.
  • the output of the PM sensor 5 increases as the accumulated amount B of the PM amount downstream of the DPF 4 increases, the relationship between the accumulated amount B and the output of the PM sensor 5 is examined in advance and stored in the memory 61. . Then, the output of the PM sensor 5 may be estimated based on this relationship and the integrated amount B obtained this time.
  • the timing (failure determination timing) for determining the failure of the DPF 4 has been reached by determining whether or not the output value Ee of the PM sensor 5 estimated in S2 exceeds a predetermined value K (see FIG. 4). It is determined whether or not (S3).
  • the predetermined value K is set to a value that can be regarded as the output of the PM sensor 5 rising. Note that, in S3, it is synonymous with determining whether or not the timing at which the output of the PM sensor 5 rises when the DPF 4 is the reference failure DPF is reached.
  • FIG. 7 and 8 are diagrams for explaining a method for estimating the average particle diameter d50 of PM.
  • FIG. 7 shows changes in sensor output with respect to the collection time before and after heating the sensor element 52.
  • FIG. 8 shows the relationship between the change rate E2 / E1 of the sensor output before and after heating the sensor element 52 and the average particle diameter d50.
  • shaft of FIG. 8 has shown the reciprocal number of the average particle diameter d50.
  • each point in FIG. 8 indicates a point of an experimental result based on the above-described EPS Spectrometer.
  • the output change rate E2 / E1 has a substantially positive correlation (proportional relationship) with the inverse of the average particle diameter d50. That is, the larger the output change rate E2 / E1, the smaller the average particle diameter d50 (the reciprocal of the average particle diameter d50 increases). This is because PM with a smaller particle diameter is in an amorphous state and has a low original conductivity, and therefore, the amount of change in conductivity when graphitized by heating increases.
  • the smaller the particle size the smaller the output value E1 before heating, while the output value E2 after heating becomes almost the same value regardless of the particle size. Therefore, the smaller the average particle diameter, the larger the output change rate E2 / E1.
  • the relation 100 in FIG. 8 is examined in advance and stored in the memory 61 as the storage unit according to the present invention.
  • the average particle diameter d50 is estimated based on the relationship 100 and the current output change rate E2 / E1. That is, first, the output value E1 (pre-heating output value) of the PM sensor 5 before heating by the heater 54 is detected (S4).
  • the sensor element 52 is heated by the heater 54 (S5).
  • the sensor element 52 may be heated at a temperature at which PM burns (600 ° C. or higher), or the sensor element 52 may be heated at a temperature at which PM does not burn (for example, about 400 ° C.).
  • FIG. 7 shows an example in which the sensor element 52 is heated at a temperature at which PM burns. Therefore, in FIG. 7, as the temperature of the sensor element 52 gradually rises due to heating, the sensor output first increases, and after a certain value E2 reaches its peak, the sensor output decreases due to PM burning at a subsequent time. To go. This is because the temperature of the sensor element 52 is a temperature at which PM does not burn from the start of heating to the peak value E2, and becomes a temperature at which PM burns after the peak value E2.
  • the peak value E2 (output value after heating) of the sensor output increased by heating the sensor element 52 is detected (S6).
  • the peak value E2 may be detected by monitoring the sensor output from the start of heating, or the time from the start of heating at which the sensor output exhibits a peak is examined in advance, and the sensor at that time is detected.
  • the output value may be detected as a peak value.
  • the sensor output value E2 detected in S6 is also an output value when the temperature of the sensor element 52 is a temperature at which PM does not burn (for example, 400 ° C.).
  • the difference between the output change rate E2 / E1 when the average particle size is small and the output change rate E2 / E1 when the average particle size is large can be made significant.
  • the rate of change E2 / E1 of the output values E1, E2 of the PM sensor 5 detected in S4, S6 rate of change of the output value E2 after heating with respect to the output value E1 before heating
  • S7 rate of change of the output value E2 after heating with respect to the output value E1 before heating
  • S8 rate of change of the output value E2 after heating with respect to the output value E1 before heating
  • S8 average particle diameter d50 is estimated based on the relationship 100 in FIG. 8 and the output change rate E2 / E1 calculated in S7 (S8).
  • the average particle diameter d50 obtained by the process of S8 is the average particle of PM discharged downstream of the DPF 4 during the collection period from the start of electrostatic collection by the process of S1 to the arrival of the failure determination timing by the process of S3. Means diameter.
  • the sensor output value E1 (pre-heating output value) detected in S4 is corrected (S9).
  • the relationship (map) between the average particle diameter d50 and the sensor output correction coefficient A1 is stored in the memory 61.
  • the correction coefficient A1 increases as the average particle diameter d50 decreases.
  • the average particle diameter d50 and the correction coefficient A1 are shown in a proportional relationship. However, the proportional relationship is not necessarily obtained, and an upward convex curve or a downward convex curve may be obtained. obtain.
  • the correction coefficient A1 is 1 when the average particle diameter d50 is a predetermined reference value d0 (for example, 60 nm), and is larger than 1 when the average particle diameter d50 is smaller than the reference value d0. It is determined to be a value smaller than 1 in a large area. In other words, the correction coefficient A1 is determined so that the sensor output after the correction in S9 becomes the sensor output when the average particle diameter d50 is the reference value d0.
  • the corrected sensor output value Er obtained in S9 is larger than a predetermined value K (see FIG. 4) (S10).
  • the predetermined value K is also an estimated output value Ee at the failure determination timing.
  • the sensor output value Er is larger than the predetermined value K (S10: YES)
  • the sensor output value Er is equal to or less than the predetermined value K (S10: NO)
  • it is determined that the DPF 4 is a normal DPF having a better DPF collection capability than the reference failure DPF (S12).
  • the average particle diameter of PM is estimated, and the sensor output is corrected based on the average particle diameter. Variations in the sensor output due to the influence of the average particle diameter can be suppressed, and further, the DPF failure determination is performed based on the sensor output in which the variation is suppressed, so that variations in the determination result can be suppressed. That is, it is possible to suppress the determination that the DPF is normal even though the DPF is normal, or that the DPF is normal despite the failure.
  • the present inventors have found that there is a correlation between the output change rate E2 / E1 of the PM sensor due to heating and the average particle diameter of PM (see FIG. 8).
  • the average particle size is estimated based on the above-described correlation, the average particle size of the particulate matter in the exhaust gas can be obtained with high accuracy. Can do.
  • FIG. 10 shows a flowchart of the failure determination process according to the second embodiment.
  • the control unit 6 executes the process of FIG. 10 instead of the process of FIG.
  • the processes of S29 and S30 shown in FIG. 10 are different from the processes of S9 and S10 according to the first embodiment shown in FIG. 6, and other processes (the processes of S21 to S28, S31, and S32) are shown in FIG. This is the same as the processing of S1 to S8, S11, and S12 according to the first embodiment shown.
  • the failure determination threshold value K (predetermined value K in FIG. 4 (also the estimated output value Ee at the failure determination timing) in FIG. 4) is corrected based on the average particle diameter d50 estimated in S28 (S29).
  • the relationship (map) between the average particle diameter d50 and the threshold correction coefficient A2 is stored in the memory 61.
  • the correction coefficient A2 decreases as the average particle diameter d50 decreases.
  • the average particle diameter d50 and the correction coefficient A2 are shown in a proportional relationship. However, in addition to the proportional relationship, there may be a case of an upward convex curve or a downward convex curve. .
  • the correction coefficient A2 is 1 when the average particle diameter d50 is a predetermined reference value d0 (for example, 60 nm), and is a value smaller than 1 when the average particle diameter d50 is smaller than the reference value d0. It is determined to be a value larger than 1 in a large region. In other words, the correction coefficient A2 is determined so that the threshold value after correction in S29 is the threshold value when the average particle diameter d50 is the reference value d0.
  • the current correction coefficient A2 is obtained based on the relationship shown in FIG. 11 and the average particle diameter d50 estimated in S28.
  • the threshold value is corrected so that the smaller the average particle diameter d50 is, the smaller the PM amount is, that is, the smaller the value is.
  • the threshold value is corrected in the same direction as the direction in which the sensor output varies depending on the average particle diameter d50. For example, when the sensor output is small due to the small average particle diameter d50, the threshold value is also corrected to a small value.
  • the DPF 4 is determined to be faulty (S31), and if it is equal to or less than the threshold Er (S30: NO), the DPF 4 is determined to be normal (S30: NO). S32).
  • threshold value correction is performed instead of sensor output correction.
  • the failure determination process executed by the control unit 6 is different from that of the first embodiment, and the other processes are the same as those of the first embodiment.
  • the failure determination process according to the third embodiment will be described below.
  • the output value Ee of the PM sensor 5 when the DPF 4 is the reference failure DPF is estimated (S2), and the failure is determined based on whether or not the estimated output value Ee has reached a predetermined value K. It has been determined whether or not the determination timing has been reached (S3).
  • the process shown in FIG. 12 is executed instead of the process of FIG. That is, the processing of S42 and S43 in FIG. 12 is different from the processing of S2 and S3 shown in FIG. 6, and the other processing (the processing of S41, S44 to S52) is the processing of S1, S4 to S12 shown in FIG. Same as processing.
  • the amount of each time point (per unit time) of PM passing through the DPF 4 when the DPF 4 is the reference failure DPF based on the operating state of the engine 2 f is estimated, and the accumulated amount B of the estimated PM amount f at each time point is estimated (S42).
  • the estimation method of the integration amount B is the same as the estimation method of the integration amount B obtained for calculating the estimated output value Ee shown in S2 of FIG. As described above, in S42, the estimated output value Ee is not estimated, but the integrated amount B correlated with the estimated output value Ee at the stage before obtaining the estimated output value Ee is estimated.
  • this predetermined amount is a value determined to be the predetermined value K (the threshold value K of S50) in FIG.
  • the integrated amount B is less than the predetermined amount (S43: NO)
  • the processing after S44 is executed assuming that the failure determination timing has been reached.
  • the processes of S42 and S43 of FIG. 12 may be executed instead of the processes of S22 and S23.
  • the amount of PM collected by the PM sensor 5 when the DPF 4 is the reference failure DPF is estimated, and the failure is determined based on whether or not the amount of PM exceeds a predetermined amount. It may be determined whether or not the determination timing has been reached. This PM amount may be estimated based on the integrated amount B. This also provides the same effect as the above embodiment.
  • PM is mainly composed of a soot component (Soot) that constitutes soot, an organic solvent soluble component (Solution Organic Fraction, SOF for short), and a sulfate component.
  • Soot soot component
  • SOF organic solvent soluble component
  • Sulfate is a product in which the oxidation product (sulfide) of sulfur in the fuel is dissolved in water in the exhaust gas and atomized.
  • ⁇ SOF content varies depending on engine operating conditions. Since the conductivity of SOF is lower than that of Soot, the resistance of PM changes depending on the SOF content. Even if the same PM amount is collected by the PM sensor with the same average particle diameter, the output of the PM sensor Will be different. Therefore, in the fourth embodiment, the average particle diameter of PM is obtained in a form that excludes the influence of SOF contained in PM.
  • a DPF failure determination process that reflects the method of estimating the average particle diameter of PM in a form that eliminates the influence of SOF will be described with reference to FIGS.
  • control unit 6 executes the process shown in FIG. 13 instead of the process shown in FIG. 6 executed in the first embodiment. Note that at the start of the process of FIG. 13, it is assumed that PM has not yet been collected by the PM sensor 5.
  • the control unit 6 When the processing of FIG. 13 is started, the control unit 6 performs electrostatic collection (S61), similarly to the processing of S1 to S3 shown in FIG. 6, and the PM sensor in the case where the DPF 4 is the reference failure DPF. 5 is estimated (S62), and it is determined whether or not the output value Ee exceeds a predetermined value K (S63). If the output value Ee is less than the predetermined value K (S63: NO), it is determined that the failure determination timing has not yet been reached, the process returns to S61, and electrostatic collection and estimation of the output value Ee are continued (S61, S62). ).
  • the average particle diameter d50 (median diameter) of PM in the exhaust gas is determined by the processing of S64 to S69, assuming that the failure determination timing has been reached.
  • the SOF volatilizes the sensor element 52 by the heater 54.
  • the soot is heated to the first temperature at which it does not burn (S64).
  • FIG. 15 is a diagram for explaining a preferable range of the first temperature.
  • the output change rate (E2 / E1) on the vertical axis in FIG. 15 is obtained by heating the sensor output value E1 when the sensor element 52 is heated to the first temperature to the first output value and the second temperature at which the soot burns.
  • the change rate of the second output value E2 with respect to the first output value E1 is shown with the sensor output value E2 at that time as the second output value. Further, in FIG.
  • the points indicated by ⁇ show the results under the conditions where the engine speed is 1654 rpm, the torque is 24 Nm, and the SOF ratio (weight percent concentration) in PM is 7.7 wt%.
  • the points indicated by ⁇ show the results under conditions where the engine speed is 2117 rpm, the torque is 83 Nm, and the SOF ratio is 1.3 wt%.
  • the first temperature is less than 200 ° C.
  • the influence of SOF on the output change rate cannot be excluded.
  • the output change rate changes according to the SOF ratio.
  • the inventor has confirmed that when the first temperature exceeds 400 ° C., the sensor output gradually decreases while being heated to the first temperature. This is probably because when the first temperature exceeds 400 ° C., the combustion of the Soot has started. From the above, the first temperature is preferably 200 ° C. or higher and 400 ° C. or lower.
  • FIG. 14 illustrates the case where the first temperature is 350 ° C.
  • the heating and holding time at the first temperature is, for example, 30 seconds or longer. If it is less than 30 seconds, the heating temperature is not stable, and the volatilization of SOF may be insufficient. However, the heating time may be less than 30 seconds as long as the SOF can be sufficiently volatilized. The heating and holding time may be long, but it takes a long time to measure, so it is preferably 3 minutes or less. FIG. 14 shows an example in which the heating and holding time is 60 seconds.
  • the influence of the SOF can be eliminated in the sensor output.
  • the PM temperature varies, and therefore the sensor output changes depending on the temperature characteristics of the PM resistance.
  • the temperature of PM collected by the sensor element 52 can be made constant regardless of the exhaust temperature by the heat treatment of S64, the influence of the exhaust temperature on the sensor output can be eliminated.
  • the first output value E1 of the PM sensor 5 when it is heated to the first temperature is detected (S65). At this time, the peak value of the sensor output during the period of heating and holding to the first temperature is detected as the first output value E1.
  • the sensor element 52 is heated to the second temperature at which the soot burns (S66), following the heating at the first temperature.
  • the second temperature is preferably 600 ° C. or higher and 1000 ° C. or lower. If it is less than 600 degreeC, there exists a possibility that combustion of Soot may become inadequate. If the temperature exceeds 1000 ° C., the sensor element 52 and the counter electrode 53 may not be able to withstand heat, and may be damaged by heat, for example.
  • FIG. 14 shows an example in which the second temperature is 800 ° C.
  • the heating and holding time at the second temperature is preferably 30 seconds or more, for example. If it is less than 30 seconds, the heating temperature is not stable, soot combustion is insufficient, and the accurate peak value E2 of the sensor output may not be detected in S67 described later. However, the heating time of less than 30 seconds may be used as long as the accurate peak value E2 can be detected. Moreover, although the time of the heating and holding to 2nd temperature may be long, since measurement takes time, 3 minutes or less are preferable.
  • the sensor output further increases from the first output value E ⁇ b> 1 by heating to the second temperature.
  • the sensor output first increases with the lapse of time from the start of heating to the second temperature, and the sensor output decreases due to the combustion of the soot at a time after peaking at a certain value E2.
  • the temperature of the sensor element 52 is a temperature at which the soot does not burn from the start of heating to the second temperature until the peak value E2, and the temperature at which the soot burns after the peak value E2. .
  • the sensor output further increases from the first output value E1 to heat the sensor element 52 to a second temperature higher than the first temperature. This is because the change of the crystalline structure of PM collected by the sensor element 52 to the graphite state that improves the conductivity is further promoted.
  • the peak value E2 of the sensor output increased by heating the sensor element 52 to the second temperature is detected as the second output value (S67).
  • the peak value E2 may be detected by monitoring the sensor output from the start of heating, or the time from the start of heating at which the sensor output exhibits a peak is examined in advance, and the sensor at that time is detected.
  • the output value may be detected as a peak value.
  • the rate of change E2 / E1 (the rate of change of the second output value E2 with respect to the first output value E1) of the output values E1 and E2 of the PM sensor 5 detected in S65 and S67 is calculated (S68).
  • the average particle diameter d50 of PM in the exhaust gas is estimated based on the output change rate E2 / E1 calculated in S68 (S69).
  • FIG. 16 shows the relationship between the change rate E2 / E1 of the sensor output value E2 at the second temperature heating and the average particle diameter d50 with respect to the sensor output value E1 at the first temperature heating.
  • shaft of FIG. 16 has shown the reciprocal number of the average particle diameter d50.
  • each point shown in FIG. 16 has shown the experimental result obtained using Engine Exhaust Particle Sizer (EEPS) Spectrometer.
  • EEPS Engine Exhaust Particle Sizer
  • the rate of change E2 / E1 between the sensor output value E1 at the first temperature and the sensor output value E2 at the second temperature correlates with the average particle diameter d50.
  • the output change rate E2 / E1 has a substantially positive correlation (proportional relationship) with the inverse of the average particle diameter d50. Therefore, the relationship 101 in FIG. 16 is examined in advance and stored in the memory 61. As shown in FIG. 15, even if the average particle diameter is the same, the output change rate changes when the first temperature changes. Therefore, the first temperature when obtaining the relationship 101 in FIG. 16 and the process of S64 It is necessary to make the first temperature at the same value.
  • the average particle diameter d50 is estimated based on the relationship 101 shown in FIG. 16 and the current output change rate E2 / E1 calculated in S68.
  • the average particle diameter d50 obtained by the process of S69 is the average particle of PM discharged downstream of the DPF 4 during the collection period from the start of electrostatic collection by the process of S61 to the arrival of the failure determination timing by the process of S63. Means diameter.
  • the SOF is volatilized but the soot is not combusted based on the output change rate E2 / E1 based on the sensor output value E1 when the sensor element 52 is heated to the first temperature at which the soot does not burn.
  • the average particle size is estimated. Thereby, it is possible to obtain a highly accurate average particle diameter excluding both the influence of SOF and the influence of exhaust temperature.
  • the sensor output value E1 at the first temperature excluding the influence of the SOF and the exhaust temperature is corrected, and the failure determination of the DPF is performed based on the corrected sensor output value Er.
  • the influence of SOF and exhaust temperature can be further eliminated.
  • the control unit 6 executes the process of FIG. 17 as the failure determination process.
  • the processing shown in FIG. 17 differs from the processing of FIG. 13 in the processing of S84 and S91, and the other processing (processing of S81 to S83, S85 to S90, and S92 to S94) is S61 to S61 shown in FIG. This is the same as the processing of S69 and S71 to S73.
  • the sensor output value E1 at the first temperature at which SOF evaporates but the soot does not burn and the sensor output value E2 at the second temperature at which the soot burns.
  • the average particle diameter d50 of PM is estimated (S85 to S90).
  • the sensor output value E0 detected in S84 is corrected based on the average particle diameter d50 of PM (S90). Specifically, the correction coefficient A1 corresponding to the current average particle diameter d50 is obtained from the map shown in FIG. 9 in the same manner as the process of S9 shown in FIG.
  • the sensor output value E1 at the first temperature is corrected, whereas in the process of the fifth embodiment, before heating to the first temperature (heating to the first temperature is started). Sensor output value E0 at the time) is corrected. This also makes it possible to determine the failure of the DPF while eliminating the influence of the SOF.
  • the control unit 6 executes the process shown in the flowchart of FIG. 18 as the failure determination process.
  • the processes in S110 and S111 shown in FIG. 18 are different from the processes in S70 and S71 in FIG. 13, and the other processes (the processes in S101 to S109, S112 and S113) are the same as those in S61 to S61 shown in FIG. This is the same as the processing of S69, S72, and S73.
  • the sensor output value E1 at the first temperature and the second temperature when the failure determination timing is reached as in the processing of S61 to S69 shown in FIG.
  • the average particle diameter d50 of PM is estimated based on the rate of change E2 / E1 with the sensor output value E2 (S101 to S109).
  • threshold correction is performed instead of sensor output correction, as in the case of the second embodiment.
  • the SOF evaporates but the soot does not burn.
  • the PM of Since the average particle diameter is estimated the average particle diameter can be obtained in a form that excludes the influence of SOF and exhaust temperature.
  • the threshold value is corrected based on the obtained average particle diameter, and the failure determination of the DPF is performed based on the comparison between the corrected threshold value and the sensor output. While being able to suppress, the influence of SOF and the influence of engine operating conditions (exhaust temperature) can be eliminated.
  • the DPF failure determination is performed based on the sensor output value E1 at the first temperature excluding the influence of the SOF and the exhaust temperature, the influence of the SOF and the exhaust temperature can be further eliminated in the failure determination.
  • failure determination processing according to a seventh embodiment of the present invention will be described.
  • the failure determination process executed by the control unit 6 is different from that in the above embodiment, and the other processes are the same as those in the above embodiments.
  • the failure determination process according to the seventh embodiment will be described below.
  • the control unit 6 executes the process of FIG. 19 as the failure determination process.
  • the process of S124 is added to the process shown in FIG. 18, and the process of S132 is different from the process of S111 shown in FIG.
  • the other processes are the same as the processes of S101 to 110, S112, and S113 shown in FIG.
  • electrostatic collection is performed (S121), similarly to the processing of S101 to S102 shown in FIG. 18, and the PM sensor 5 in the case where the DPF 4 is the reference failure DPF.
  • the output value Ee is estimated (S122), and it is determined whether or not the output value Ee exceeds a predetermined value K (S123). If the output value Ee is less than the predetermined value K (S123: NO), it is determined that the failure determination timing has not yet been reached, the process returns to S121, and electrostatic collection and estimation of the output value Ee are continued (S121, S122). ).
  • the sensor output value E0 before heating the sensor element 52 to the first temperature is detected in the next S125 (S124).
  • This sensor output value E0 is also the sensor output at the start of heating to the first temperature, as shown in the lower part of FIG.
  • the sensor output value E1 at the first temperature at which the SOF evaporates but the soot does not burn and the sensor output value E2 at the second temperature at which the soot burns.
  • the PM average particle diameter d50 is estimated, and the failure determination threshold value K is corrected based on the average particle diameter d50 (S125 to S131).
  • threshold correction is performed in the same manner as in the sixth embodiment, but the sensor output value to be compared with the corrected threshold is the sensor output value E1 at the first temperature in the sixth embodiment. On the other hand, in the seventh embodiment, it is the sensor output value E0 before heating. This also makes it possible to execute DPF failure determination in a manner that eliminates the influence of SOF.
  • failure determination processing according to an eighth embodiment of the present invention will be described. Below, it demonstrates centering on the process different from the process of each above-mentioned embodiment.
  • the failure determination process executed by the control unit 6 is different from the process executed in the above embodiment, and the other processes are the same as those in the above embodiments.
  • a failure determination process according to the eighth embodiment will be described.
  • the control unit 6 executes the process shown in the flowchart of FIG. 20 as the failure determination process.
  • the processes shown in S142 and S143 are different from the processes in S62 and S63 shown in FIG. 13, and the other processes (the processes of S141 and S144 to S153) are S61 and S64 shown in FIG. This is the same as the process of S73.
  • the processes shown in S142 and S143 are the same as the processes in S42 and S43 shown in FIG. That is, in the eighth embodiment, similarly to the third embodiment, the PM accumulated amount B passing through the DPF 4 when the DPF 4 is the reference failure DPF is estimated, and the failure determination timing is reached based on the accumulated amount B. Is judged.
  • the processing after reaching the failure determination timing is the same as the processing shown in FIG. Also by this, the same effect as the case of each above-mentioned embodiment can be acquired.
  • the control unit 6 executes the process shown in the flowchart of FIG. 21 as the failure determination process.
  • the processing of S162 and S163 in FIG. 21 is different from the processing of S82 and S83 shown in FIG. 17, and the other processing (the processing of S161, S164 to S174) is S81, S84 to S94 shown in FIG. It is the same as the process.
  • the processing of S162 and S163 is the same as the processing of S42 and S43 shown in FIG. That is, in the ninth embodiment, as in the third embodiment, the PM accumulated amount B passing through the DPF 4 when the DPF 4 is the reference failure DPF is estimated, and the failure determination timing is reached based on the accumulated amount B. Is judged.
  • the processing after reaching the failure determination timing is the same as the processing shown in FIG. Also by this, the same effect as each above-mentioned embodiment can be acquired.
  • the configurations of the filter failure detection device and the particulate matter detection device according to the tenth embodiment are the same as those according to the above-described embodiments.
  • the process executed by the control unit 6 is different from the failure determination process executed in each embodiment described above.
  • the control unit 6 executes the process shown in the flowchart of FIG.
  • the process of FIG. 22 is a process executed in addition to or in place of the DPF failure determination process shown in FIGS. 6, 10, 12, 13, and 17 to 21. It is assumed that PM has not yet been collected by the PM sensor 5 at the start of processing shown in the flowchart of FIG.
  • the control unit 6 first performs electrostatic collection of PM on the PM sensor 5 (S181). Next, it is determined whether or not the output of the PM sensor 5 has reached a predetermined output value E0 (S182). If not reached yet (S182: NO), the process returns to S181 to continue monitoring of electrostatic collection and sensor output.
  • the average particle diameter of PM is estimated (S183 to S188) in the same manner as the processing of S64 to S69 shown in FIG. That is, the average particle diameter of PM based on the rate of change E2 / E1 between the sensor output value E1 at the first temperature at which the SOF evaporates but the soot does not burn and the sensor output value E2 at the second temperature at which the soot burns. Is estimated.
  • the mass of PM discharged downstream of the DPF 4 during the collection period is estimated (S189). This mass is the sum of the masses of all PM particles.
  • the PM sensor 5 outputs a value correlated with the mass of PM collected by the sensor element 52.
  • the mass of PM collected by the sensor element 52 correlates with the mass of PM discharged downstream of the DPF 4. That is, the sensor output correlates with the integrated value of the PM mass discharged downstream of the DPF 4 in the period from the start of collection to the PM sensor 5 to the output of the current sensor output value.
  • the mass of PM discharged downstream of the DPF 4 can be estimated based on the sensor output.
  • the PM mass can be obtained in a form excluding the influence of the SOF and the exhaust temperature.
  • the relationship between the sensor output and the PM mass in the exhaust gas is examined in advance and stored in the memory 61.
  • This relationship is a relationship in which the PM mass increases as the sensor output increases.
  • the PM mass corresponding to the first output value E1 is estimated based on the relationship stored in the memory 61.
  • the PM mass is estimated in S189.
  • the process of S189 is performed at any timing as long as the first output value E1 is detected. It may be executed.
  • the number of PM particles is calculated by the following equation 2.
  • the PM specific gravity in Equation 2 is set to a predetermined value, specifically, for example, 1 g / cm 3 .
  • the PM specific gravity may be stored in the memory 61.
  • PM average volume x PM specific gravity in the denominator of Equation 2 means an average mass per PM discharged downstream of the DPF 4 in the collection period.
  • PM particle number PM mass / (PM average volume ⁇ PM specific gravity). . . (Formula 2).
  • the number of PM particles discharged downstream of the DPF 4 in a specific period (collection period) can be obtained. Based on this number of particles, for example, the failure of the DPF 4 Judgment can be made. Further, since the number of PM particles is estimated based on the average particle diameter from which the influence of the SOF and the exhaust temperature has been eliminated, it is possible to obtain a highly accurate number of PM particles from which the influence of the SOF and the exhaust temperature has been eliminated.
  • the control unit 6 executes the process shown in the flowchart of FIG. 23 in place of the process shown in FIG. In FIG. 23, the process of S209 is different from the process of S189 of FIG. 22, and the other processes (the processes of S201 to S208 and S210) are the same as the processes of S181 to S188 and S190 shown in FIG. is there.
  • the PM mass is estimated based on the first output value E1, but in S209 shown in FIG. 23, a predetermined value before heating to the first temperature (in other words, at the start of heating to the first temperature) is obtained.
  • the PM mass is estimated based on the sensor output value E0. Specifically, the PM mass corresponding to the predetermined sensor output value E0 is examined in advance and stored in the memory 61. Then, the PM mass stored in the memory 61 may be read in S209. Note that the process of S209 may be executed at any timing as long as the sensor output reaches the predetermined output value E0.
  • the PM mass is estimated based on the sensor output value E0 before heating, and the number of PM particles is calculated based on the PM mass. Also by this, the same effect as in the tenth embodiment can be obtained.
  • the present invention is not limited to the contents described in the above embodiments and claims, and various modifications can be made without departing from the concept of the present invention.
  • either one of the sensor output correction and the threshold correction is performed, but both may be performed.
  • the process of S29 shown in FIG. 10 is executed after S9 shown in FIG. 6 or before S9.
  • a weight is set between the sensor output correction in S9 and the threshold correction in S29, and the sensor output and the threshold are corrected by this weighting. For example, if the sensor output correction weight is 70% (0.7) and the threshold correction weight is 30% (0.3), in S9, only 70% of the sensor output correction is executed.
  • the output is corrected, and in S29, the threshold value is corrected by 30% when only threshold value correction is executed. Then, instead of S10 shown in FIG. 6, it is determined whether or not the corrected sensor output value Er is larger than the corrected threshold value Kr. Also by this, the same effect as each above-mentioned embodiment can be acquired.
  • the average particle diameter is estimated based on the output change rate E2 / E1, but the PM particle diameter depends on the operating state of the engine 2 (engine speed, fuel injection amount). Etc.), the average particle diameter of PM may be estimated based on the operating state. In this case, the relationship (map) between the operating state of the engine 2 and the average particle diameter is examined in advance and stored in the memory 61. And based on this relationship and the driving
  • the average particle diameter may be estimated based on the rate of change E1 / E2 of the output value E1 before heating with respect to the output value E2 after heating. In this case, the smaller the rate of change E1 / E2, the smaller the average particle size.
  • the average particle diameter is estimated based on the rate of change E1 / E2 of the sensor output value E1 at the first temperature with respect to the sensor output value E2 at the second temperature. good. In this case, the smaller the rate of change E1 / E2, the smaller the average particle size.
  • the PM sensor is used for the purpose of detecting the failure of the DPF.
  • the PM sensor may be used for purposes other than detecting the failure.
  • a PM sensor may be disposed upstream of the DPF, and this PM sensor may be used for detecting the amount of PM discharged from the engine (the amount of PM flowing into the DPF).
  • the sensor output by correcting the sensor output according to the present invention, a highly accurate PM amount in which the influence of the average particle diameter is suppressed can be obtained.
  • the DPF failure determination is performed based on the comparison between the estimated output value of the PM sensor and the actual output value at a certain collection time.
  • the failure is determined based on the inclination of the sensor output. Judgment may be made.
  • the output change (slope) of the PM sensor when the DPF is the reference failure DPF is estimated, and the estimated output change (slope) is set as a failure determination threshold value.
  • the threshold is compared with the actual output change (slope), and if the actual output change is larger than the threshold, it is determined that the DPF has failed, and if it is smaller, it is determined that the DPF is normal.
  • the actual output change and threshold value are corrected based on the average particle diameter of PM. Also by this, the same effect as each above-mentioned embodiment can be acquired.
  • the counter electrode 53 is formed on the surface of the sensor element 52 shown in FIG. 24 that extends in the longitudinal direction, as shown in FIG.
  • An example of a PM sensor configured so that the counter electrode 53 faces the side surface of the cover 51 is shown.
  • the PM sensor may have a configuration as shown in FIGS. That is, the counter electrode 53 is formed on the surface on one end side in the longitudinal direction of the sensor element 52 as in the structure shown in FIG. 25, or the counter electrode 53 is covered in the cover 51 as in the structure shown in FIG. You may employ
  • S4 to S8, S24 to S28, S44 to S48, S64 to S69, S85 to S90, and S104 to S109 in FIGS. 6, 10, 12, 13, and 17 to 23 are used.
  • the particle size estimation unit corresponds to the particle size estimation unit.
  • the control unit 6 that executes the processing of S82, S83, S92 to S94, S102, S103, S111 to S113, S122, S123, S132 to S134, S142, S143, S151 to S153, S162, S163, S172 to S174 This corresponds to the failure determination unit in the invention.
  • the control unit 6 that executes the processes of S9, S29, S49, S70, S91, S110, S131, S150, and S171 of FIGS.
  • 6, 10, 12, 13, and 17 to 21 is the correction unit in the present invention. Equivalent to.
  • the control unit 6 that executes the processes of S185, S203, and S205 corresponds to the heating control unit in the present invention.
  • the control unit 6 that executes the processing of S107, S108, S126, S128, S129, S145, S147, S148, S166, S168, S169, S184, S186, S187, S204, S206, and S207 corresponds to the acquisition unit in the present invention. To do.
  • the control unit 6 that executes the processes of S189 and S209 of FIGS. 22 and 23 corresponds to the mass estimation unit in the present invention.
  • the control unit 6 that executes the processes of S190 and S210 in FIGS. 22 and 23 corresponds to the particle number calculation unit in the present invention.

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Abstract

　Selon la présente invention, lorsqu'un DPF est le filtre servant de critère d'évaluation de défaut, une unité de commande (6) estime la valeur de sortie d'un capteur MP situé en aval du DPF (S2), et décide si la valeur de sortie estimée dépasse une valeur prescrite (S3). Lorsque la valeur prescrite a été dépassée (S3 : OUI), l'unité de commande détecte la valeur de sortie du capteur MP (S4), et ensuite chauffe le capteur MP avec un dispositif de chauffage (S5). De plus, l'unité de commande détecte la valeur de sortie du capteur MP chauffé par chauffage (S6), calcule le taux de changement de la valeur de sortie avant et après chauffage (S7), et sur la base du taux de changement obtenu ainsi, estime le diamètre de particule moyen de la MP (S8), et corrige la sortie du capteur sur la base du diamètre de particule moyen (S9). Sur la base d'une comparaison de la sortie de capteurs corrigée et d'une valeur de seuil, l'unité de commande détermine s'il existe un défaut du DPF (S10-S12).
PCT/JP2015/078060 2014-10-02 2015-10-02 Dispositif de détection de défaut de filtre, et dispositif de détection de matière particulaire Ceased WO2016052734A1 (fr)

Priority Applications (3)

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EP15845761.4A EP3203220B1 (fr) 2014-10-02 2015-10-02 Dispositif de détection de particules
US15/516,163 US10578518B2 (en) 2014-10-02 2015-10-02 Filter failure detection device and particulate matter detection device
CN201580053457.1A CN107076690B (zh) 2014-10-02 2015-10-02 过滤器的故障检测装置、颗粒状物质检测装置

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JP2015184870A JP6426072B2 (ja) 2014-10-02 2015-09-18 フィルタの故障検出装置、粒子状物質検出装置

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WO2017163650A1 (fr) * 2016-03-22 2017-09-28 株式会社デンソー Dispositif de détection de matière particulaire
JP2017173289A (ja) * 2016-03-22 2017-09-28 株式会社Ｓｏｋｅｎ 粒子状物質検出装置
EP3853452A1 (fr) * 2018-09-20 2021-07-28 Robert Bosch GmbH Procédé de détection sélective de tailles de particule de nombres de particules dans les gaz d'échappement d'un dispositif de combustion
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JP2012092700A (ja) * 2010-10-26 2012-05-17 Toyota Motor Corp フィルタ故障検出装置及び方法
JP2012189049A (ja) * 2011-03-14 2012-10-04 Denso Corp 粒子状物質検出装置及びパティキュレートフィルタの故障検出装置
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WO2017163650A1 (fr) * 2016-03-22 2017-09-28 株式会社デンソー Dispositif de détection de matière particulaire
JP2017173289A (ja) * 2016-03-22 2017-09-28 株式会社Ｓｏｋｅｎ 粒子状物質検出装置
CN108885163A (zh) * 2016-03-22 2018-11-23 株式会社电装 颗粒状物质检测装置
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CN108885163B (zh) * 2016-03-22 2021-04-30 株式会社电装 颗粒状物质检测装置
EP3853452A1 (fr) * 2018-09-20 2021-07-28 Robert Bosch GmbH Procédé de détection sélective de tailles de particule de nombres de particules dans les gaz d'échappement d'un dispositif de combustion
US12239933B2 (en) * 2020-09-29 2025-03-04 Daikin Industries, Ltd. Correcting system, and correcting method

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