WO2020036092A1 - Détecteur de particules fines - Google Patents

Détecteur de particules fines Download PDF

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Publication number
WO2020036092A1
WO2020036092A1 PCT/JP2019/030817 JP2019030817W WO2020036092A1 WO 2020036092 A1 WO2020036092 A1 WO 2020036092A1 JP 2019030817 W JP2019030817 W JP 2019030817W WO 2020036092 A1 WO2020036092 A1 WO 2020036092A1
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Prior art keywords
electrode
electric field
fine particles
charge
removal
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PCT/JP2019/030817
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English (en)
Japanese (ja)
Inventor
英正 奥村
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日本碍子株式会社
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Publication of WO2020036092A1 publication Critical patent/WO2020036092A1/fr

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    • 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
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/68—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H05F3/02—Carrying-off electrostatic charges by means of earthing connections

Definitions

  • the present invention relates to a particle detector.
  • ions are generated by corona discharge with a charge generating element, and the ions are used to charge fine particles in a gas into charged fine particles.
  • Patent Document 1 a removing electrode is provided between the charge generating element and the collecting electrode, an electric power is connected to the removing electrode to generate an electric field on the removing electrode, and the electric field is used to generate fine particles. It has also been proposed to improve the detection accuracy of the number of fine particles by collecting and removing uncharged charges (excess charges) with a removal electrode.
  • the present invention has been made to solve such a problem, and has as its main object to simplify the configuration of a particle detector as compared with the related art.
  • the particle detector of the present invention A fine particle detector used to detect fine particles in a gas, A housing having a gas flow path through which the gas passes, A charge generation unit that generates a charge by discharging when a discharge voltage is applied, and adds the charge to the fine particles in the gas introduced into the gas flow path to make the charged fine particles; A removing electrode provided in the gas flow path on the downstream side of the flow of the gas from the charge generation unit, for removing an excess charge not charged to the fine particles, A collecting electrode provided in the gas flow path on the downstream side of the gas flow from the removing electrode, for collecting the charged fine particles, A detection unit that detects the amount of the fine particles based on a physical amount that changes according to the charged fine particles collected by the collection electrode, With The removal electrode is connected to ground, does not have its own power supply for generating an electric field on the removal electrode, and has an electric field generated between the removal electrode and a voltage application electrode disposed around the removal electrode. Removing the excess charge using Things.
  • the charge generation unit generates charges to convert fine particles in the gas introduced into the gas flow path into charged fine particles, and a removal electrode removes excess charge not added to the fine particles. Is collected by the collecting electrode.
  • the detection unit detects the amount of the fine particles based on a physical amount that changes according to the charged fine particles collected by the collection electrode.
  • the removal electrode is connected to the ground, does not have its own power supply for generating an electric field on the removal electrode, and generates an electric field generated between the removal electrode and a voltage application electrode arranged around the removal electrode. Utilize to remove excess charge. Therefore, the configuration can be simplified as compared with a conventional fine particle detector having a unique power supply for generating an electric field at the removal electrode.
  • charge includes ions in addition to positive charges and negative charges.
  • physical quantity may be a parameter that changes according to the collection target, and includes, for example, current.
  • amount of fine particles includes, for example, the number, mass, and surface area of the fine particles.
  • the voltage application electrode is a discharge electrode of the charge generation unit to which a discharge voltage is applied by a discharge power supply, and the removal electrode is provided between the removal electrode and the discharge electrode.
  • the surplus electric charge may be removed by using an electric field generated in the above.
  • a power supply for discharge can be used instead of a power supply unique to the removal electrode.
  • the removal electrode may be provided on a surface different from the surface on which the discharge electrode is provided. In this case, an electric field is easily generated between the removal electrode and the discharge electrode.
  • the discharge voltage is preferably a periodic voltage (a voltage having periodicity). This makes it possible to generate charges intermittently.
  • the collecting electrode collects the charged fine particles using an electric field generated on the collecting electrode by a collecting voltage applied to an electric field generating electrode by a collecting power supply.
  • the voltage applying electrode is the electric field generating electrode
  • the removing electrode removes the surplus charge by using an electric field generated between the removing electrode and the electric field generating electrode.
  • a power supply for collection can be used instead of a power supply unique to the removal electrode.
  • the removal electrode may be provided on a surface different from the surface on which the electric field generating electrode is provided. In this case, an electric field is easily generated between the removal electrode and the electric field generating electrode.
  • the collection voltage may be a DC voltage. This makes it possible to continuously remove excess charges during the period of detecting fine particles.
  • both the discharge electrode and the electric field generating electrode may be used as the voltage application electrode, or either one of them may be used.
  • FIG. 3 is an explanatory diagram of the particle detector 10.
  • FIG. 2 is a perspective view of the particle detection element 20. AA sectional drawing of FIG. FIG. 3 is a sectional view taken along line BB of FIG. 2.
  • FIG. 2 is an exploded perspective view of the particle detection element 20.
  • FIG. 4 is an explanatory diagram of a sine wave voltage.
  • FIG. 2 is a cross-sectional view of the particle detector 110.
  • FIG. 3 is a cross-sectional view of the particle detector 210.
  • FIG. 4 is an explanatory diagram of a pulse voltage.
  • FIG. 3 is a cross-sectional view of the particle detector 310.
  • FIG. 4 is a cross-sectional view of the particle detector 410.
  • FIG. 1 is an explanatory view of a particle detector 10 according to one embodiment of the present invention
  • FIG. 2 is a perspective view of a particle detection element 20
  • FIG. 3 is a cross-sectional view taken along line AA of FIG. 2
  • FIG. 5 is an exploded perspective view of the particle detecting element 20.
  • the vertical direction, the horizontal direction, and the front-back direction are as shown in FIGS.
  • the particle detector 10 detects the number of particles 26 (see FIG. 4) contained in exhaust gas flowing through the exhaust pipe 12 of the engine.
  • the particle detector 10 includes a particle detection element 20 and an attached unit 80 including various power supplies 36 and 56 and a number detection unit 60.
  • the fine particle detection element 20 is attached to a ring-shaped pedestal 16 fixed to the exhaust pipe 12 while being inserted into a columnar support 14.
  • the particle detecting element 20 is protected by the protective cover 18.
  • a hole (not shown) is provided in the protective cover 18, and the exhaust gas flowing through the exhaust pipe 12 passes through the gas passage 24 provided at the lower end of the particle detection element 20 through the hole.
  • the holes in the protective cover 18 are adjusted so that the speed of the exhaust gas introduced into the gas flow path 24 is substantially constant regardless of the speed of the exhaust gas flowing through the exhaust pipe 12.
  • the fine particle detection element 20 includes a housing 22 including a charge generation unit 30, a surplus charge removal unit 40, a collection unit 50, and a heater electrode 72.
  • the casing 22 is a long rectangular parallelepiped that is long in a direction intersecting with the axial direction of the exhaust pipe 12 (here, a direction substantially orthogonal to the axis).
  • the housing 22 is an insulator, and is made of, for example, ceramics such as alumina.
  • the lower end 22 a of the housing 22 is arranged inside the exhaust pipe 12, and the upper end 22 b is arranged outside the exhaust pipe 12.
  • a gas flow path 24 is provided at a lower end 22 a of the housing 22.
  • Various terminals are provided on the upper end 22 b of the housing 22.
  • the axial direction of the gas flow path 24 matches the axial direction of the exhaust pipe 12.
  • the gas flow path 24 extends from a rectangular gas inlet 24 a provided on the front surface of the housing 22 to a rectangular gas outlet 24 b provided on the rear surface of the housing 22. It is a continuous rectangular parallelepiped space.
  • the housing 22 includes a pair of left and right flow path walls 22c and 22d that form the gas flow path 24 (see FIG. 2).
  • the charge generation section 30 is provided on the flow path wall 22c so that charges are generated in the gas flow path 24 near the gas inlet 24a.
  • the charge generation section 30 has a discharge electrode 32 and two ground electrodes 34.
  • the discharge electrode 32 is provided along the inner surface of the flow path wall 22c, and has a plurality of fine protrusions around a rectangle as shown in FIG.
  • the two ground electrodes 34, 34 are rectangular electrodes, and are embedded in the flow path wall 22c so as to be parallel to the discharge electrodes 32 at intervals.
  • a high-frequency high voltage (periodic voltage) of the discharge power source 36 (one of the attached units 80) is applied between the discharge electrode 32 and the two ground electrodes 34, 34, so that both of the two are connected. Air discharge occurs due to a potential difference between the electrodes. At this time, a portion of the housing 22 between the discharge electrode 32 and the ground electrodes 34, 34 serves as a dielectric layer. By this air discharge, the gas existing around the discharge electrode 32 is ionized and a positive charge 28 is generated.
  • the ground electrodes 34, 34 are connected to ground (earth).
  • the fine particles 26 contained in the gas enter the gas flow path 24 from the gas inlet 24 a, and charge 28 generated by air discharge of the charge generation unit 30 when passing through the charge generation unit 30. Are added to form the charged fine particles P, and then move backward. Further, of the generated electric charges 28, those not added to the fine particles 26 move backward with the electric charges 28. Of the generated charges 28, those not added to the fine particles 26 are referred to as surplus charges.
  • the surplus charge removing unit 40 is provided downstream of the charge generating unit 30 and upstream of the collecting unit 50.
  • the surplus charge removing section 40 has a pair of removing electrodes 42 and 44.
  • One removal electrode 44 is provided along the inner surface of the left channel wall 22 c and is exposed in the gas channel 24.
  • the other removal electrode 42 is provided along the inner surface of the right channel wall 22 d and is exposed in the gas channel 24.
  • the pair of removal electrodes 42 and 44 are disposed at positions facing each other, and both are connected to ground (earth).
  • the collection unit 50 is provided downstream of the charge generation unit 30 and the surplus charge removal unit 40 in the gas flow path 24.
  • the collecting section 50 is for collecting the charged fine particles P, and has an electric field generating electrode 52 and a collecting electrode 54.
  • the electric field generating electrode 52 is provided along the inner surface of the left channel wall 22 c and is exposed in the gas channel 24.
  • the collecting electrode 54 is provided along the inner surface of the right channel wall 22 d and is exposed in the gas channel 24.
  • the electric field generating electrode 52 and the collecting electrode 54 are provided at positions facing each other.
  • the electric field generating electrode 52 is an electrode to which a DC voltage V1 (positive potential, for example, about 2 kV) is applied by a trapping power supply 56 (one of the attached units 80).
  • the collection electrode 54 is an electrode connected to the ground (earth) via the ammeter 62. Thereby, a relatively strong electric field is generated between the electric field generation electrode 52 and the collection electrode 54 of the collection unit 50. Therefore, the charged fine particles P flowing through the gas flow path 24 are attracted to and collected by the collection electrode 54 by the relatively strong electric field.
  • the surplus charge 28 not added to the fine particles 26 is attracted to and captured by the removal electrode 42 by the electric field generated between the discharge electrode 32 and the removal electrode 42, and is grounded. Or is attracted to the removal electrode 42 by an electric field generated between the electric field generating electrode 52 and the removal electrode 42, is captured and discarded by the ground, or is removed by an electric field generated between the discharge electrode 32 and the removal electrode 44. It is attracted to the electrode 44 and captured and discarded to the ground, or it is attracted to the removal electrode 44 by an electric field generated between the electric field generating electrode 52 and the removal electrode 44 and captured and discarded to the ground.
  • the removal electrodes 42 and 44 remove the surplus electric charge 28 by using the discharge power supply 36 and the collection power supply 56, and have their own power supply for generating an electric field in the removal electrodes 42 and 44. Absent. In this way, the surplus charge removing unit 40 prevents the surplus charge 28 from being collected by the collecting electrode 54 of the collecting unit 50 and being counted as the number of the fine particles 26.
  • each of the removing electrodes 42 and 44 of the surplus charge removing section 40 The size of each of the removing electrodes 42 and 44 of the surplus charge removing section 40, the strength of the electric field between the discharge electrode 32 and the removing electrode 42, the strength of the electric field between the discharge electrode 32 and the removing electrode 44, The size of each electrode 52, 54 of the collecting part 50, the intensity of the electric field generated between the two electrodes 52, 54, the distance between the removal electrode 42 and the discharge electrode 32, the distance between the removal electrode 44 and the discharge electrode 32, the removal The distance between the electrode 42 and the electric field generating electrode 52 and the distance between the removing electrode 44 and the electric field generating electrode 52 are set such that the charged fine particles P are collected by the collecting electrode 54 without being collected by the removing electrode 44.
  • the electric charge 28 not added to the fine particles 26 is removed by the removing electrode 44.
  • the mobility ⁇ i [m 2 / V ⁇ s] of the electric charge 28 is 10 times or more the mobility ⁇ p [m 2 / V ⁇ s] of the charged fine particles P, and the electric field required for collection is Can be easily reduced by one digit or more.
  • a plurality of sets of the electric field generation electrode 52 and the collection electrode 54 may be provided.
  • the number detection unit 60 is one of the attached units 80, and includes an ammeter 62 and a number measurement device 64 as shown in FIG.
  • the ammeter 62 has one terminal connected to the collecting electrode 54 and the other terminal connected to the ground.
  • the ammeter 62 measures a current based on the electric charge 28 of the charged fine particles P collected by the collecting electrode 54.
  • the number measuring device 64 calculates the number of the fine particles 26 based on the current of the ammeter 62.
  • the heater electrode 72 is embedded in the housing 22.
  • the heater electrode 72 is a belt-like heating element (see FIG. 5) drawn in zigzag.
  • the heater electrode 72 is connected to a power supply device (not shown), and generates heat when energized by the power supply device.
  • the heater electrode 72 heats each electrode such as the housing 22, the removal electrodes 42 and 44, the electric field generation electrode 52, and the collection electrode 54.
  • the fine particle detecting element 20 is composed of seven sheets S1 to S7.
  • Each of the sheets S1 to S7 is formed of the same material as that of the housing 22.
  • the first sheet S1, the second sheet S2,... are referred to from left to right
  • the right side of each of the sheets S1 to S7 is referred to as the front side
  • the left side is referred to as the back side.
  • the thickness of each of the sheets S1 to S7 may be set as appropriate, and may be, for example, all the same or different.
  • a heater electrode 72 is provided on the surface of the first sheet S1. One end and the other end of the heater electrode 72 are disposed above the front surface of the first sheet S1, and the heater electrode terminals 75 provided above the back surface of the first sheet S1 through through holes in the first sheet S1. , 75 respectively.
  • Ground electrodes 34, 34 are provided on the surface of the second sheet S2.
  • the ground electrodes 34, 34 are combined into one wiring 34a.
  • the end of the wiring 34a is arranged above the front surface of the second sheet S2, and is provided above the back surface of the first sheet S1 through through holes of the second sheet S2 and the first sheet S1. It is connected to the electrode terminal 35.
  • the wiring 44a of the removing electrode 44 and the wiring 54a of the collecting electrode 54 are provided along the vertical direction.
  • the upper ends of the wirings 44a and 54a are connected to the removal electrode terminal 45 and the collection electrode terminal 55 provided above the back surface of the first sheet S1 through through holes in the second sheet S2 and the first sheet S1, respectively. ing.
  • the discharge electrode 32, the removal electrode 44, and the electric field generation electrode 52 are provided on the surface of the third sheet S3.
  • the removal electrode 44 is connected to the wiring 44a of the second sheet S2 via the through hole of the third sheet S3, and further connected to the removal electrode terminal 45 via this wiring 44a.
  • a gas flow path 24, that is, a rectangular parallelepiped space is provided at the lower end side of the fourth sheet S4.
  • the removal electrode 42 and the collection electrode 54 are provided on the back surface of the fifth sheet S5.
  • the removal electrode 42 is connected to the wiring 34a of the second sheet S2 through each through hole of the fourth sheet S4 and the third sheet S3, and is connected to the removal electrode terminal 45 via the wiring 34a.
  • the collecting electrode 54 is connected to the wiring 44a of the second sheet S2 through each through hole of the fourth sheet S4 and the third sheet S3, and is connected to the collecting electrode terminal 55 via the wiring 44a.
  • the sixth sheet S6 has no electrodes or wires.
  • the wiring 32a of the discharge electrode 32 and the wiring 52a of the electric field generating electrode 52 are provided along the vertical direction.
  • the lower end of the wiring 32a is connected to the discharge electrode 32 provided on the third sheet S3 through the through holes of the fourth to sixth sheets S4 to S6.
  • the lower end of the wiring 52a is connected to the electric field generating electrode 52 provided on the third sheet S3 through the through holes of the fourth to sixth sheets S4 to S6.
  • the upper ends of the wirings 32a and 52a are connected to the discharge electrode terminals 33 and the electric field generating electrode terminals 53 provided above the surface of the seventh sheet S7 through through holes in the seventh sheet S7, respectively.
  • the fine particle detection element 20 can be manufactured using a plurality of ceramic green sheets. Specifically, for each of the plurality of ceramic green sheets, cutouts, through holes and grooves are provided as necessary, electrodes and wiring patterns are screen-printed, and then laminated and fired. Note that the notch, the through hole, and the groove may be filled with a material (for example, an organic material) that burns out during firing. Thus, the fine particle detection element 20 is obtained. Subsequently, the discharge electrode terminal 33 and the electric field generation electrode terminal 53 of the fine particle detection element 20 are connected to the discharge power source 36 and the collection power source 56 of the attached unit 80, respectively.
  • a material for example, an organic material
  • the ground electrode terminal 35 and the removal electrode terminal 45 of the fine particle detection element 20 are connected to the ground, and the collection electrode terminal 55 is connected to the number measuring device 64 via the ammeter 62. Further, the heater electrode terminals 75, 75 are connected to a power supply device (not shown). By doing so, the fine particle detector 10 can be manufactured.
  • the fine particle detection element 20 is attached to the exhaust pipe 12 of the engine as described above (see FIG. 1).
  • the fine particles 26 contained in the exhaust gas introduced into the housing 22 from the gas inlet 24 a are charged with the charges 28 (positive charges in this case) generated by the discharge of the charge generating unit 30 and are charged fine particles. It becomes P.
  • the charged fine particles P pass through the surplus charge removing unit 40 as they are and reach the collecting unit 50.
  • the electric charge 28 not added to the fine particles 26 is attracted to the removing electrodes 42 and 44 of the surplus charge removing section 40 and is discarded to the ground via the removing electrodes 42 and 44.
  • the unnecessary charges 28 not added to the fine particles 26 hardly reach the collection unit 50.
  • the charged fine particles P reaching the collection unit 50 are collected by the collection electrode 54 by the collection electric field generated by the electric field generation electrode 52. Then, a current based on the charge 28 of the charged fine particles P collected by the collecting electrode 54 is measured by the ammeter 62, and the number measuring device 64 calculates the number of the fine particles 26 based on the current.
  • the number measuring device 64 integrates (accumulates) the current value over a predetermined period, obtains the integrated value (accumulated charge amount), divides the accumulated charge amount by the elementary charge, and calculates the total number of charges (the number of collected charges).
  • the number Nt of the fine particles 26 collected by the collecting electrode 54 is obtained by dividing the number of collected electric charges by the average value of the number of electric charges added to one fine particle 26 (the average number of charges) (see below). Equation (1)).
  • the collecting electrode 54 is heated by the heater electrode 72 by heating the collecting electrode 54 by the heater electrode 72 at regular intervals or at a timing when the amount of deposition reaches a predetermined amount. Refresh the electrode surface.
  • the heater electrode 72 can also incinerate the fine particles 26 attached to the inner peripheral surface of the housing 22.
  • the electric charge is generated by the charge generation unit 30 so that the fine particles 26 in the gas introduced into the gas flow path 24 are converted into the charged fine particles P, and the surplus electric charge not added to the fine particles 26 is generated. 28 are removed by the removal electrodes 42 and 44, and the charged fine particles P are collected by the collection electrode 54.
  • the number detecting unit 60 detects the number of the fine particles 26 based on a current that changes according to the charged fine particles P collected by the collecting electrode 54.
  • the removal electrodes 42 and 44 are connected to the ground, do not have a unique power supply for generating an electric field on the removal electrodes 42 and 44, and have the removal electrodes 42 and 44 and the voltage application electrodes ( The surplus electric charge 28 is removed using an electric field generated between the discharge electrode 32 and the electric field generating electrode 52). Therefore, the configuration can be simplified as compared with a conventional particle detector having a unique power supply for generating an electric field at the removal electrodes 42 and 44.
  • the removal electrode 42 is provided on a surface different from the surface on which the discharge electrode 32 and the electric field generating electrode 52 are provided (here, the surface facing the electrode). Therefore, an electric field is easily generated between the removal electrode 42 and the discharge electrode 32 or between the removal electrode 42 and the electric field generating electrode 52.
  • the collecting electrode 54 uses the electric field to collect the charged fine particles P, the collected fine particles P can be efficiently collected by the collecting electrode 54.
  • the housing 22 incorporates the heater electrode 72, the temperature of the housing 22 can be controlled by the heater electrode 72.
  • the fine particles 26 attached to the collecting electrode 54 and the like can be incinerated by heating the heater electrode 72 with the use of the fine particle detecting element 20 to refresh the collecting electrode 54 and the like.
  • the charge 28 can be generated intermittently.
  • the periodic voltage preferably has an absolute value of the peak voltage of 2 to 5 kV. By doing so, the charges 28 can be sufficiently generated by the charge generation unit 30, and the surplus charges 28 can be sufficiently removed by the removal electrodes 42 and 44 using the electric field generated when the charge generation unit 30 discharges. You can also.
  • the periodic voltage is preferably a pulse wave or a sine wave. This makes it easier to prevent the charge 28 generated by the discharge from accumulating on the charge generation unit 30 for a long time. Sine waves are more preferable because noise is less likely to be generated during discharge than pulse waves. Further, the sine wave alternates between positive and negative, and it is preferable that the absolute value of one of the positive and negative peak voltages is larger than the absolute value of the other peak voltage.
  • FIG. 6 shows a sine wave voltage as an example of the high frequency high voltage of the discharge power supply 36.
  • the zero volt is not a dotted line but a solid line (a line below the middle line (dashed line) of the sine wave). Therefore, the absolute value of the positive peak voltage is larger than the absolute value of the negative peak voltage.
  • Part of the charge generated by the positive voltage is deposited on the discharge electrode 32, but if the deposited charge remains, the charge 28 is less likely to be generated at the next discharge.
  • the sinusoidal voltage of FIG. 6 the accumulated charge disappears during the period of the negative voltage. Therefore, charges 28 can be continuously and efficiently generated.
  • each of the pair of removing electrodes 42 and 44 of the surplus charge removing unit 40 is connected to the ground, but the removing electrode 44 may be omitted as in the fine particle detector 110 shown in FIG. . 7, the same components as those in the above-described embodiment are denoted by the same reference numerals. Also in the fine particle detector 110, the same effect as in the above-described embodiment can be obtained except that the surplus electric charge 28 is not removed by the removing electrode 44.
  • the removal electrode 42 may be eliminated as in the case of the fine particle detector 210 shown in FIG. 8, the same components as those in the above-described embodiment are denoted by the same reference numerals.
  • the same effect as in the above-described embodiment can be obtained except that the surplus electric charge 28 is not removed by the removing electrode 42.
  • the removal electrode 42 is provided on a surface different from the surface on which the discharge electrode 32 and the electric field generating electrode 52 are provided (here, the opposite surface), FIG. An electric field is more likely to be generated between the removal electrode 42 and the discharge electrode 32 and between the removal electrode 42 and the electric field generating electrode 52 as compared with the fine particle detector 210.
  • the removal electrode 44 is provided on the same surface as the surface on which the discharge electrode 32 and the electric field generating electrode 52 are provided.
  • the particle detector 110 of FIG. 7 is more preferable than the particle detector 210 of FIG.
  • the number of the charged fine particles P is determined based on the current flowing through the collection electrode 54.
  • the number of the charged fine particles P may be determined based on the current flowing through the removing electrode.
  • the removal electrode 44 and the collection unit 50 are eliminated, and the ammeter 62 of the number detection unit 60 is connected to the removal electrode 42.
  • the number detection unit 60 calculates the number of the surplus electric charges 28 based on the physical quantity (current) that changes according to the surplus electric charge 28 collected by the removal electrode 42,
  • the number of the charged fine particles P may be obtained by subtracting the number of the surplus electric charges 28 from the total number.
  • the removal electrode 42 is connected to the ground, does not have its own power supply for generating an electric field on the removal electrode 42, and is connected to the removal electrode 42 and a voltage application electrode (discharge electrode 32) disposed therearound.
  • the surplus electric charge 28 is removed by using an electric field generated between the electric charges. Further, the charged fine particles P are discharged from the gas discharge port 24b without being collected by the removal electrode 42.
  • the gas flow path 24 may be divided into a plurality of sections on the downstream side of the charge generation section 30.
  • a partition wall 22e is provided on the gas flow path 24 downstream of the charge generation unit 30, and the gas flow path 24 is divided into two branch paths 241.
  • 241 may be provided with a removal electrode 442 and a collecting section 450.
  • the removal electrodes 442 are provided on both the front and back surfaces of the partition wall 22e.
  • the collection unit 450 includes a pair of the collection electrode 454 provided on the surface of the partition wall 22e and the electric field generation electrode 452 provided on the flow path wall 22d opposed thereto.
  • each removal electrode 442 is connected to the ground
  • each collection electrode 454 is connected to the ammeter 62 (see FIG. 4) of the individual number detection unit 60
  • each electric field generation electrode is connected.
  • 452 is connected to the collecting power supply 56 (see FIG. 4).
  • the fine particle detector 410 calculates the number of fine particles in the gas by adding up the number of fine particles 26 detected by the number detecting unit 60 connected to each collecting electrode 454.
  • Each of the removal electrodes 442 is connected to the ground, does not have its own power supply for generating an electric field on the removal electrode 442, and has a voltage application electrode (discharge electrode 32 or electric field generation electrode 452) disposed around the removal electrode 442.
  • the surplus electric charge 28 is removed by utilizing the electric field generated between the above-mentioned steps.
  • the charge generation unit 30 is provided on the flow path wall 22c of the gas flow path 24.
  • the charge generation unit 30 may be provided on the flow path wall 22d, or may be provided on both of the flow path walls 22c and 22d. Good.
  • the charge generation unit 30 is configured by the discharge electrode 32 provided along the inner surface of the gas flow path 24 and the two ground electrodes 34, 34 buried in the housing 22. Any configuration may be used as long as it generates charges by discharging. For example, instead of embedding the ground electrodes 34, 34 in the wall of the gas flow channel 24, they may be provided along the inner surface of the gas flow channel 24. Alternatively, as described in Patent Literature 1, the charge generation unit may be constituted by a needle electrode and a counter electrode.
  • the electric field generating electrode 52 is exposed to the gas flow path 24, but is not limited thereto and may be embedded in the housing 22. Further, instead of the electric field generating electrode 52, a pair of electric field generating electrodes disposed so as to sandwich the collecting electrode 54 from above and below is provided on the housing 22, and an electric field generated by a voltage applied between the pair of electric field generating electrodes is provided. Then, the charged fine particles P may be moved toward the collection electrode 54.
  • the surplus electric charge 28 is removed by using the electric field generated between the removal electrodes 42 and 44 and the discharge electrode 32, and the electric charge generated between the removal electrodes 42 and 44 and the electric field generation electrode 52.
  • the surplus electric charge 28 may be removed by using only the electric field generated between the removal electrodes 42 and 44 and the discharge electrode 32.
  • the surplus electric charge 28 may be removed by using only the electric field generated between the removing electrodes 42 and 44 and the electric field generating electrode 52.
  • the voltage V1 is applied to the electric field generation electrode 52.
  • the flow path width (the distance between the two electrodes 52 and 54) is kept small.
  • the value By setting the value to an appropriate value (for example, 0.01 mm or more and less than 0.2 mm), the charged fine particles P having a sharp Brownian motion can collide with the collection electrode 54. Thereby, the collecting electrode 54 can collect the charged fine particles P.
  • the fine particle detection element 20 may not include the electric field generating electrode 52. In this case, the surplus electric charge 28 is removed by the electric field generated between the discharge electrode 32 and the removal electrodes 42 and 44.
  • the present invention is not particularly limited to the exhaust pipe 12 of the engine.
  • Such a tube may be used.
  • the fine particle detecting element 20 detects the number of fine particles.
  • the fine particle detecting element 20 may detect the mass or surface area of the fine particles.
  • the mass of the fine particles can be obtained, for example, by multiplying the number of the fine particles by the average mass of the fine particles, and the relationship between the accumulated charge amount and the mass of the collected fine particles is stored in a storage device in advance as a map. Using this map, the mass of the fine particles can also be obtained from the accumulated charge amount.
  • the surface area of the fine particles can be determined in the same manner as the mass of the fine particles.
  • the present invention is applicable to, for example, a particle detector for detecting the number of particles in exhaust gas of a power machine such as an automobile.

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Abstract

La présente invention concerne un détecteur de particules fines 10 qui comprend un boîtier 22 qui est utilisé pour détecter des particules fines dans un gaz et comporte un trajet d'écoulement de gaz 24 que le gaz traverse, une unité de génération de charge 30 pour générer une charge par l'application et la décharge d'une tension de décharge, des électrodes d'élimination 42, 44 pour éliminer une charge en excès 28 non maintenue par les particules fines 26, une électrode de collecte 54 pour collecter les particules fines chargées P, et une unité de détection 60 pour détecter la quantité de particules fines sur la base du courant circulant à travers l'électrode de collecte 54. Les électrodes d'élimination 42, 44 sont reliées à la terre. Il n'y a pas d'alimentation électrique unique pour générer des champs électriques à partir des électrodes d'élimination 42, 44. Les champs électriques générés entre les électrodes d'élimination 42, 44 et les électrodes d'application de tension (par exemple, une électrode de charge-décharge 32 et une électrode de génération de champ électrique 52) disposées à proximité sont utilisés pour éliminer la charge 28 qui est en excès.
PCT/JP2019/030817 2018-08-13 2019-08-06 Détecteur de particules fines WO2020036092A1 (fr)

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JP2018-152354 2018-08-13
JP2018152354 2018-08-13

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WO2020036092A1 true WO2020036092A1 (fr) 2020-02-20

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070029477A1 (en) * 2005-04-29 2007-02-08 Sionex Corporation Compact gas chromatography and ion mobility based sample analysis systems, methods, and devices
JP2012251926A (ja) * 2011-06-06 2012-12-20 Ngk Spark Plug Co Ltd 微粒子センサ
JP2017211239A (ja) * 2016-05-24 2017-11-30 日本特殊陶業株式会社 微粒子センサ
WO2017208889A1 (fr) * 2016-06-03 2017-12-07 日本碍子株式会社 Élément de génération de charges et détecteur de nombre de particules fines
WO2018139346A1 (fr) * 2017-01-26 2018-08-02 日本碍子株式会社 Dispositif de détection du nombre de particules fines

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070029477A1 (en) * 2005-04-29 2007-02-08 Sionex Corporation Compact gas chromatography and ion mobility based sample analysis systems, methods, and devices
JP2012251926A (ja) * 2011-06-06 2012-12-20 Ngk Spark Plug Co Ltd 微粒子センサ
JP2017211239A (ja) * 2016-05-24 2017-11-30 日本特殊陶業株式会社 微粒子センサ
WO2017208889A1 (fr) * 2016-06-03 2017-12-07 日本碍子株式会社 Élément de génération de charges et détecteur de nombre de particules fines
WO2018139346A1 (fr) * 2017-01-26 2018-08-02 日本碍子株式会社 Dispositif de détection du nombre de particules fines

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