JP5193911B2 - Particulate matter detector - Google Patents

Description

  The present invention relates to a particulate matter detection device. More specifically, it is small in size, can be manufactured at low cost, and can perform high-accuracy measurement while suppressing the influence of parasitic capacitance generated between the wires connected to the measurement electrode. The present invention relates to a particulate matter detection device capable of performing the above.

  Flue exhaust gas and diesel engine exhaust gas contain particulate matter (PM) such as soot, which causes air pollution. In order to remove these, a filter (diesel particulate filter: DPF) made of ceramic or the like is widely used. A ceramic DPF can be used for a long period of time. However, defects such as cracks and erosion may occur due to thermal deterioration or the like, and particulate matter may leak although it is in a small amount. When such a defect occurs, it is extremely important from the viewpoint of preventing air pollution to immediately detect the occurrence of the defect and recognize the abnormality of the apparatus.

  As a method for detecting the occurrence of such a defect, there is a method of providing a particulate matter detection device on the downstream side of the DPF (see, for example, Patent Document 1).

JP 60-123761 A

  The invention described in Patent Document 1 measures the amount of particulate matter by charging the particulate matter by corona discharge and measuring its ionic current. As described above, in the method of charging the particulate matter and measuring the ionic current, since the ionic current charged in the particulate matter is weak, a large detection circuit is required to detect the weak ionic current. There was a problem of becoming expensive. In addition, when the exhaust gas has a high flow rate, the particulate matter cannot be effectively charged, so the measured value of the particulate matter is smaller than the amount of the particulate matter actually contained in the exhaust gas. There was a problem that the error was large. In addition, for example, the parasitic capacitance generated between the wirings connected to the measurement electrode may greatly affect the measurement value, which makes it difficult to perform accurate measurement.

  The present invention has been made in view of the above-described problems, is small in size, has a small measurement error, can be manufactured at low cost, and has a parasitic capacitance generated between wirings connected to measurement electrodes. It is an object of the present invention to provide a particulate matter detection device capable of suppressing the influence and performing highly accurate measurement.

  In order to achieve the above object, the present invention provides the following particulate matter detection apparatus.

[1] A detection device main body that is long in one direction in which at least one through hole is formed at one end, and at least a pair of measurement electrodes that are disposed on the inner surface or inside of one wall that forms the through hole. And a pair of measurement electrode wires extending from the pair of measurement electrodes toward the other end of the main body of the detection device, and inside the opposing walls forming the through hole, and the pair of measurements At least one pair of dust collecting electrodes buried in the outside of the wall forming the through-hole and covered with a dielectric material rather than a position where the electrode is buried, and at least one measurement electrode wiring and dielectric of the pair of measurement electrode wirings And a grounded shield electrode for blocking at least part of the current flowing through the dielectric and flowing to the at least one measurement electrode wiring through the dielectric, and flows into the through hole. Contained in the charged particulate matter contained in the fluid or in the fluid flowing into the through-hole charged by the discharge generated in the through-hole by applying a voltage to the pair of dust collecting electrodes It is possible to electrically adsorb the particulate matter to the wall surface of the through hole, and by measuring the change in the electrical characteristics of the wall forming the through hole by the pair of measurement electrodes A particulate matter detection device capable of detecting particulate matter adsorbed on the wall surface of the through hole.

[2] The shield electrode is disposed at a position between the pair of measurement electrode wires, and includes a first shield electrode for cutting off a current flowing between the pair of measurement electrode wires through the dielectric. ]. The particulate matter detection device according to claim 1.

[3] The shield electrode is disposed at a position between the pair of measurement electrode wires and a wire connected to the high-voltage dust collection electrode to which a high voltage is applied among the pair of dust collection electrodes. The particulate matter detection device according to [1] or [2], further including a second shield electrode and a third shield electrode including a grounded dust collecting electrode grounded from the pair of dust collecting electrodes.

[4] A measurement unit for measuring a change in electrical characteristics between the pair of measurement electrodes, and a pair of measurement unit connection wirings for electrically connecting the measurement unit and the pair of measurement electrode wires And at least one measurement unit connection wiring of the pair of measurement unit connection wirings is grounded to cut off at least part of the current flowing through the space between the pair of measurement unit connection wirings. The particulate matter detection device according to any one of [1] to [3], wherein the particulate matter detection device is covered with a shield electrode for connection wiring.

[5] A measurement unit for measuring a change in electrical characteristics between the pair of measurement electrodes, and a pair of measurement unit connection wires for electrically connecting the measurement unit and the pair of measurement electrode wires And the measurement unit is disposed in at least a part of the periphery of the measurement unit internal wiring electrically connected to the pair of measurement unit connection wirings, and is adjacent in the measurement unit The particulate matter according to any one of [1] to [3], further comprising a grounded shield electrode for the measurement unit wiring for blocking at least a part of the current flowing between the measurement unit wirings arranged. Substance detection device.

[6] The particulate matter detection device according to [5], wherein the measurement-unit wiring and the measurement-unit wiring shield electrode are printed wirings arranged on an insulating printed board.

[7] Heating for temperature control for stably measuring a change in electrical characteristics of the wall forming the through-hole, which is disposed inside the detection device main body along the wall surface of the through-hole. The particulate matter detection device according to any one of [1] to [6], further comprising a unit.

[8] The particulate matter according to any one of [1] to [7], wherein at least one of an inlet portion into which the fluid flows and an outlet portion from which the fluid flows out of the through hole is expanded. Detection device.

[9] The cross-sectional shape orthogonal to the central axis of the detection device main body gradually becomes thicker from one end side toward the central part in the penetration direction of the through hole, and is the thickest at the central part, and further the other end The particulate matter detection device according to any one of [1] to [8], wherein the particulate matter detection device has a shape that gradually becomes thinner toward the portion side.

[10] The [1] to [1], wherein the particulate matter adsorbed on the wall surface of the through hole can be oxidized and removed by applying a voltage to the pair of dust collecting electrodes to cause a discharge in the through hole. 9] The particulate matter detection device according to any one of [9].

[11] The particulate matter detection device according to any one of [1] to [10], wherein the discharge that occurs in the through hole is one type selected from the group consisting of silent discharge, streamer discharge, and corona discharge. .

[12] The particulate form according to any one of [1] to [11], wherein the dielectric is at least one selected from the group consisting of alumina, cordierite, mullite, glass, zirconia, magnesia, and titania. Substance detection device.

  In the particulate matter detection device of the present invention, at least a pair of dust collection electrodes are embedded in the wall of the detection device main body forming a through hole, and a voltage is applied to the pair of dust collection electrodes to discharge into the through hole. The particulate matter existing in the through hole can be charged by the discharge, and the charged particulate matter is electrically adsorbed on the wall surface of the through hole or the measurement electrode arranged on the inner surface of the wall. It is possible to make it. Then, the change in the electrical characteristics of the wall forming the through hole is measured by a pair of measurement electrodes arranged opposite to each other with a predetermined interval, and flows into the through hole in the exhaust gas flowing downstream of the DPF. It becomes possible to measure the mass of the particulate matter in the exhaust gas.

  Thus, the particulate matter detection device of the present invention does not directly measure all the particulate matter contained in the exhaust gas flowing downstream of the DPF, but measures the particulate matter that has flowed into the through hole. Based on this measured value, the amount of particulate matter in the whole exhaust gas can be estimated. As a result, it is possible to measure a minute amount of particulate matter that could not be detected by a conventional inspection method.

  Moreover, since the particulate matter detection device of the present invention does not measure the total amount of exhaust gas as described above, the device can be downsized and installed in a narrow space. Furthermore, with such miniaturization, the particulate matter detection device can be manufactured at low cost.

  In addition, even when the total flow rate of the exhaust gas flowing downstream of the DPF is high, only a part of the exhaust gas (that is, particulate matter contained in the exhaust gas) is introduced into the through hole. The substance can be effectively charged, and a measurement value with less error can be obtained.

  In addition, the detection device main body is formed long in one direction, and a through hole is formed at one end thereof, and a pair of measurement electrodes and a pair of dust collecting electrodes are disposed (embedded). And it becomes possible to insert only the part of each electrode into the pipe | tube through which high temperature exhaust gas distribute | circulates, and let the other edge part side have come out from the pipe | tube. As a result, it is possible to place portions that are preferably not exposed to high temperatures, such as the extraction terminals of the electrodes, out of the piping, and perform highly accurate and stable measurement.

  In addition, since the measurement electrode wiring connected to the pair of measurement electrodes has a grounded shield electrode for cutting off at least a part of the current flowing through the dielectric through the measurement electrode wiring, the measurement electrode wiring The electrical characteristics between the pair of measurement electrodes can be satisfactorily detected by suppressing the influence on the measured value due to, for example, the influence of the parasitic capacitance generated between the measurement electrode wirings. This makes it possible to accurately measure changes in the electrical characteristics of the walls forming the through holes.

It is a front view showing typically one embodiment of the particulate matter detection device of the present invention. 1B is a side view showing one side surface of the particulate matter detection device shown in FIG. 1A. FIG. FIG. 1B is a side view showing the other side surface of the particulate matter detection device shown in FIG. 1A. It is a rear view of the particulate matter detection device shown in FIG. 1A. It is a schematic diagram which shows the A-A 'cross section of FIG. 1B. It is a schematic diagram which shows the B-B 'cross section of FIG. It is a schematic diagram which shows the C-C 'cross section of FIG. It is a schematic diagram which shows the D-D 'cross section of FIG. It is a schematic diagram which shows the E-E 'cross section of FIG. It is a schematic diagram which shows the F-F 'cross section of FIG. It is a schematic diagram which shows typically other embodiment of the particulate-material detection apparatus of this invention. It is a circuit diagram which shows typically the electrical circuit of the measurement part used for further another embodiment of the particulate matter detection apparatus of this invention. FIG. 5 is a schematic view showing another embodiment of the particulate matter detection device of the present invention and corresponding to a schematic view showing a cross section of one embodiment of the particulate matter detection device of the present invention shown in FIG. 4. It is a schematic diagram which shows the cross section orthogonal to a central axis and including a through-hole which shows other embodiment of the particulate matter detection device of the present invention. It is a schematic diagram which shows the cross section which does not contain a through-hole orthogonal to a center axis | shaft which shows other embodiment of the particulate matter detection apparatus of this invention. FIG. 3 is a schematic diagram schematically showing a configuration of a detection device main body in Example 1.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and the ordinary knowledge of those skilled in the art is within the scope of the present invention. Based on the above, it should be understood that design changes, improvements, and the like can be made as appropriate.

[1] Particulate matter detection device:
1A is a front view schematically showing one embodiment of the particulate matter detection device of the present invention, and FIG. 1B is a side view showing one side surface of the particulate matter detection device shown in FIG. 1A. 1C is a side view showing the other side surface of the particulate matter detection device shown in FIG. 1A, and FIG. 1D is a rear view of the particulate matter detection device shown in FIG. 1A. FIG. 2 is a schematic view showing a cross section taken along line AA ′ of FIG. 1B. 3 is a schematic view showing a BB ′ cross section of FIG. 2, FIG. 4 is a schematic view showing a CC ′ cross section of FIG. 2, and FIG. 5 is a DD view of FIG. FIG. 6 is a schematic diagram showing a cross section EE ′ of FIG. 2, and FIG. 7 is a schematic diagram showing a cross section FF ′ of FIG. 2.

  As shown in FIGS. 1A to 1D and FIGS. 2 to 7, the particulate matter detection device 100 of the present embodiment is unidirectional in which at least one through hole (cavity) 2 is formed in one end portion 1 a. Long detection device main body 1, at least a pair of measurement electrodes 15 and 16 disposed on the inner surface or inside of one wall forming through-hole 2, and detection device main body 1 from a pair of measurement electrodes 15 and 16, respectively. A pair of measurement electrode wirings 15b and 16b extending toward the other end 1b of the first electrode and the walls facing each other forming the through hole 2 and penetrating from the embedded position of the pair of measurement electrodes 15 and 16 At least one pair of dust collecting electrodes 11 and 12 embedded in the outside of the wall forming the hole 2 and covered with a dielectric, and at least one measurement electrode wiring and dielectric of the pair of measurement electrode wirings 15b and 16b Placed and dielectric At least one of the measurement electrode wiring 15b via, for blocking at least a portion of the current flowing to 16b, in which comprises a shield electrode 17 which is grounded.

  The particulate matter detection device 100 according to the present embodiment applies a voltage to the charged particulate matter contained in the fluid flowing into the through-hole 2 or the pair of dust collecting electrodes 11 and 12. The particulate matter contained in the fluid flowing into the through hole 2 that is charged by the discharge generated in the through hole 2 can be electrically adsorbed on the wall surface of the through hole 2. Furthermore, the change in the electrical characteristics of the wall forming the through hole 2 is measured by the pair of measurement electrodes 15 and 16 to detect the mass of the particulate matter adsorbed on the wall surface of the through hole 2. Is possible. Thereby, the particulate matter detection device 100 of the present embodiment can detect the particulate matter contained in the exhaust gas by allowing the exhaust gas or the like to pass through the through hole 2.

  Thus, the particulate matter detection device 100 according to the present embodiment does not directly measure all particulate matter contained in the exhaust gas flowing downstream such as DPF, but the particulate matter that has flowed into the through-hole 2. A substance can be measured, and the amount of particulate matter in the entire exhaust gas can be estimated based on the measured value. As a result, it is possible to measure a minute amount of particulate matter that could not be detected by a conventional inspection method.

  Moreover, since the particulate matter detection device 100 of this embodiment does not measure the total amount of exhaust gas as described above, the particulate matter detection device 100 can be downsized and installed in a narrow space. It becomes possible. Furthermore, with such miniaturization, the particulate matter detection device 100 can be manufactured at low cost.

  Further, even when the total flow rate of the exhaust gas flowing downstream such as DPF is high, only a part of the exhaust gas (that is, particulate matter contained in the exhaust gas) is introduced into the through hole 2, so that the through hole 2 The particulate matter inside can be effectively charged, and a measurement value with little error can be obtained.

  Further, the detection device main body 1 is formed long in one direction, the through hole 2 is formed at one end 1a thereof, and a pair of dust collecting electrodes 11 and 12 and a pair of measurement electrodes 15 and 16 are disposed. (Being buried), the through hole 2 and each electrode (for example, the dust collecting electrode 11 and the pair of measuring electrodes 15 and 16) are inserted into a pipe through which high-temperature exhaust gas flows, and the other end 1b side is piped. It becomes possible to make it go out of. As a result, it is possible to place portions that are preferably not exposed to high temperatures, such as the extraction terminals of the electrodes, out of the piping, and perform highly accurate and stable measurement.

  Further, a grounded shield electrode for cutting off at least a part of the current flowing through the measurement electrode wirings 15b and 16b through the dielectric with respect to the measurement electrode wirings 15b and 16b connected to the pair of measurement electrodes 15 and 16. 17, the measurement electrode wirings 15 b and 16 b affect the measurement value, for example, parasitic between the measurement electrode wirings 15 b and 16 b or between the measurement electrode wirings 15 b and 16 b and other wirings. It is possible to satisfactorily detect the electrical characteristics between the pair of measurement electrodes 15 and 16 while suppressing the influence of the capacitance. Thereby, it becomes possible to measure the change of the electrical characteristics of the wall forming the through hole 2 with high accuracy.

  The parasitic capacitance described above refers to a capacitance generated by various wirings, circuits, and nearby metal objects. The particulate matter detection device 100 of this embodiment measures the electrical characteristics of the impedance and capacitance between the pair of measurement electrodes 15 and 16, and the particulate matter adsorbed from the change in electrical characteristics such as the measured impedance. Can be used to detect the particulate matter (mass) in the exhaust gas, but when measuring the electrical characteristics such as impedance described above, the measurement electrode wirings 15b and 16b are used. When the influence of the parasitic capacitance increases, an error may occur in the measured value.

  For example, as shown in FIG. 5, the measurement electrode wirings 15 b and 16 b are arranged on the same plane in the thickness direction of the detection device main body 1 from one end 1 a of the detection device main body 1 toward the other end 1 b. In the case where they are opposed to each other, a current flows between the measurement electrode wirings 15b and 16b through the dielectric that constitutes the detection device main body 1. Therefore, electrostatic capacitance (parasitic capacitance) is generated between the measurement electrode wirings 15b and 16b. For this reason, a value obtained by adding the parasitic capacitance to the capacitance between the pair of measurement electrodes 15 and 16 is measured as a measurement value. That is, when the electrical characteristics between the pair of measurement electrodes 15 and 16 are detected, the electrical characteristics between the measurement electrode wirings arranged to face each other are also detected.

  Therefore, in the particulate matter detection device 100 of the present embodiment, the first shield electrode 17a is disposed as a shield electrode 17 at a position between the pair of measurement electrode wirings 15b and 16b. The first shield electrode 17a is grounded. When a current flows from one measurement electrode wiring 15b through a dielectric, the current is interrupted by the first shield electrode 17a before reaching the other measurement electrode wiring 16b. The influence of the parasitic capacitance generated between the measurement electrode wirings 15b and 16b can be eliminated. As described above, the particulate matter detection device of the present embodiment suppresses the influence of the measurement electrode wirings 15b and 16b extending from the pair of measurement electrodes 15 and 16 by the shield electrode 17 while suppressing the influence of the measurement electrode wirings 15b and 16b. , 16 can be detected, so that the measurement error problem due to the influence of the measurement electrode wirings 15b, 16b can be solved. Thereby, it becomes possible to measure the change of the electrical characteristics of the wall forming the through hole 2 with high accuracy.

  Note that the shield electrode used in the particulate matter detection device of this embodiment eliminates the influence of the parasitic capacitance caused by the measurement electrode wirings 15b and 16b, and selectively measures the current flowing between the pair of measurement electrodes 15 and 16. If it can do, it will not be limited to the 1st shield electrode 17a arrange | positioned in the position between a pair of measurement electrode wiring 15b, 16b as shown in FIG.

  For example, in each measurement electrode wiring, a current may flow to a dust collection electrode for collecting particulate matter and a wiring connected to the dust collection electrode, and parasitic capacitance may be generated. Therefore, as shown in FIG. 2, the shield electrode 17 of the particulate matter detection device 100 of the present embodiment is applied with a high voltage from the pair of measurement electrode wires 15 b and 16 b and the pair of dust collection electrodes 11 and 12. The second shield electrode 17b disposed between the wiring 11b connected to the high voltage dust collecting electrode 11 and the grounded dust collecting electrode 12 grounded from the pair of dust collecting electrodes 11 and 12. And the third shield electrode 17c.

  That is, the pair of measurement electrode wirings 15b and 16b, the pair of dust collection electrodes 11 and 12 and the wiring 11b are laminated in the thickness direction of the detection device main body 1 with a dielectric interposed therebetween, and thus occur between them. A shield electrode 17 (for example, the second shield electrode 17b and the third shield electrode 17c) for eliminating the influence of the parasitic capacitance may be disposed. Thus, in the particulate matter detection device of the present embodiment, the shield electrode is disposed also in the thickness direction of the detection device body, and is connected to the measurement electrode wiring, each electrode other than the measurement electrode wiring, and the electrode thereof. It may be configured so as to eliminate the influence of parasitic capacitance generated in the wiring.

  In the particulate matter detection device of this embodiment, the grounded ground collection electrode of the pair of dust collection electrodes is used as a part of the shield electrode (that is, the above-described third shield electrode). Yes.

  As described above, the particulate matter detection device of the present embodiment can more accurately measure the current flowing between the pair of measurement electrodes by effectively cutting off the excess current flowing into the measurement electrode wiring. .

  Note that at least one through hole 2 needs to be formed in the detection device main body 1 used in the particulate matter detection device of the present embodiment, and there may be two or more. Further, since the detection device main body 1 is formed of a dielectric, the pair of dust collecting electrodes 11 and 12 and the various wirings 11b, 13b, 15b, and 16b are in a state of being covered with the dielectric.

  Moreover, it is necessary to provide at least one pair of the measurement electrodes 15 and 16, and two or more pairs may be provided. FIG. 2 shows an example in which the pair of measurement electrodes 15 and 16 are disposed on the inner surface of one wall forming the through hole 2. It may be embedded inside the wall.

  Moreover, there is no restriction | limiting in particular about the shape of a pair of measurement electrode, When the particulate matter was made to adsorb | suck to the wall of a through-hole, it arrange | positioned so that the change of the electrical property of the wall could be measured A pair of electrodes may be used. In addition, as shown in FIG. 5, it is preferable that a pair of measurement electrodes 15 and 16 are linear, and are long facing the inner surface of the wall of the through-hole 2, or its inside. Each of the pair of measuring electrodes 15 and 16 having a shape is branched into a plurality of branches (for example, as shown in FIG. 5, branching into a comb shape) and has a plurality of facing portions. (For example, it is preferable that the comb-like portions are arranged so as to face each other at a predetermined interval). By configuring in this way, it is possible to take a long (wide) portion of the pair of measurement electrodes 15 and 16 that are arranged opposite to each other, and to obtain a more accurate measurement value.

  Moreover, the particulate matter detection device of the present invention includes, for example, a measurement unit 50 for measuring a change in electrical characteristics between a pair of measurement electrodes 15 and 16 (see FIG. 2), as shown in FIG. Further, the measurement unit 50 and a pair of measurement electrode wirings 15b and 16b (see FIG. 5) may further include a pair of measurement unit connection wirings 61 and 62 for electrical connection. Here, FIG. 8 is a schematic view schematically showing another embodiment of the particulate matter detection device of the present invention.

  The above-described measuring unit 50 is preferably capable of measuring the capacitance between the pair of measurement electrodes 15 and 16 (see FIG. 5), and can measure not only the capacitance but also the impedance. A suitable LCR meter or impedance analyzer can be preferably used. And this measurement part 50 and a pair of measurement electrode wiring 15b, 16b (more specifically, each extraction terminal 15a, 16a (refer FIG. 5) of a pair of measurement electrode wiring 15b, 16b) is a pair of They are electrically connected by measurement unit connection wirings 61 and 62.

  In the particulate matter detection device 200 shown in FIG. 8, at least one of the pair of measurement unit connection wirings 61 and 62 passes through the space between the pair of measurement unit connection wirings 61 and 62. It is covered with a grounded connection wiring shield electrode 63 for interrupting at least a part of the flowing current. In addition, the code | symbol 64 in FIG. 8 shows the shield wiring 64 electrically connected to the shield electrode (for example, 1st shield electrode 17a in FIG. 5) arrange | positioned inside the detection apparatus main body 1. FIG.

  With this configuration, it is possible to eliminate the influence of the parasitic capacitance due to the measurement unit connection wirings 61 and 62 that electrically connect the detection device main body 1 and the measurement unit 50, thereby realizing more accurate measurement. be able to. 8 shows an example in which the connection wiring shield electrode 63 is disposed so as to cover the one measurement unit connection wiring 61, but the influence on the current measured by the measurement unit 50 is taken into consideration. Then, the connection wiring shield electrode 63 may be disposed on both of the measurement unit connection wirings 61 and 62.

  The shield electrode for connection wiring described above is an electrode made of a conductive material, arranged so as to cover the measurement unit connection wiring, and a part of which is grounded to the ground, between the measurement unit connection wiring, or This is an electrode for preventing a current from flowing from another wiring or the like to the measurement unit connection wiring. Such a shield electrode for connection wiring can be constituted by a thin conductive wire, metal foil, or metal mesh, and can be used by being disposed so as to cover the surface of the measurement unit connection wiring with coating. That is, the shield electrode for connection wiring and the measurement unit connection wiring can be configured in the same manner as known shield wires.

  Further, in the particulate matter detection device of the present embodiment, at least part of the current flowing between the adjacent internal wirings is also applied to the internal wiring of the measurement unit, as in the particulate matter detection device described so far. A structure for blocking (hereinafter, such a structure may be referred to as a “shield structure”) may be provided.

  Here, FIG. 9 is a circuit diagram schematically showing an electrical circuit of a measurement unit used in still another embodiment of the particulate matter detection device of the present invention. As shown in FIG. 9, the particulate matter detection device 300 of the present embodiment includes a measurement unit 50 for measuring a change in electrical characteristics between a pair of measurement electrodes 15 and 16 (see FIG. 2), a measurement And a pair of measurement unit connection wires 61 and 62 for electrically connecting the unit 50 and the pair of measurement electrode wirings 15b and 16b (see FIG. 5). The measurement unit 50 includes a pair of measurement units. Between the measurement-unit wirings 51 and 52 electrically connected to the connection wirings 61 and 62 and between the measurement-unit wirings arranged in at least a part of the periphery of the measurement-unit wirings 51 and 52 and adjacently arranged in the measurement unit 50 There is a grounded shield electrode 54 for the measurement unit wiring for cutting off at least a part of the current flowing through the measurement unit wiring 52 and the measurement unit wiring 53 (for example).

  With this configuration, it is possible to eliminate the influence of the parasitic capacitance due to the wiring (in-measurement-unit wiring) arranged inside the measurement unit 50, and it is possible to realize more accurate measurement.

  When the shield electrode for the measurement unit wiring is arranged inside the measurement unit, the measurement value is affected by the parasitic capacitance of the measurement unit wiring even if the shield electrode for the measurement unit wiring is not arranged in all the measurement unit wirings. It suffices if it is arranged at least in the range that exerts the above.

  For example, in the measurement unit shown in FIG. 9, a current flows from one measurement unit internal wiring 51 to one measurement electrode (for example, measurement electrode 15 (see FIG. 5)), and the other measurement electrode (for example, measurement) arranged oppositely. A current to be measured flows from the electrode 16 (see FIG. 5) into the measuring unit 50. In the measurement unit 50, the voltage of the current flowing from one measurement unit wiring 51 is V1, the current to be measured flows into the other measurement unit wiring 52, and passes through the resistor 56 (resistance value is Rs) and the operational amplifier 55. The impedance (| Z |) measured by the pair of measurement electrode wirings 15b and 16b when the voltage after the operation is V2 has the relationship of the following formula (1).

  V2 = V1 / | Z | × Rs (1)

  For this reason, when considering the influence of the wiring within the measuring section, as shown in FIG. 9, the measuring section wiring 52 in the measuring section wiring 52 through which the current flowing from the measuring electrode passes is within the range up to the entrance side of the resistor 56 and the operational amplifier 55. It is preferable to arrange the shield electrode 54 for wiring. Needless to say, the shield electrode for the measurement unit wiring may be arranged in a range other than the above. The in-measurement-unit wiring 52 and the in-measurement-unit wiring shield electrode 54 can be configured by printed wiring arranged on an insulating printed board.

  Thus, in the particulate matter detection device of this embodiment, the current to be measured among the wiring inside the detection device body, the wiring connecting the detection device body and the measurement unit, and the wiring inside the measurement unit. High-precision measurement can be realized by preventing an excess current from flowing through the wiring through which the current flows.

  In addition, the particulate matter detection device 100 of the present embodiment can exert its effect particularly when the particulate matter passing through the through hole 2 is to be discharged from the diesel engine.

[1-1] Configuration of particulate matter detection device:
Hereinafter, each component of the particulate matter detection device will be described more specifically.

[1-1a] Detection device body:
The main body of the detection device is a part that becomes a base of the particulate matter detection device and is long in one direction in which at least one through hole is formed at one end. The main body of the detection device is made of a dielectric, and at least a pair of dust collecting electrodes is disposed inside each of the opposing walls forming the through hole, and a voltage is applied to the pair of dust collecting electrodes. As a result, a discharge can be generated in the through hole.

  The dielectric constituting the detection device body is preferably at least one selected from the group consisting of alumina, cordierite, mullite, glass, zirconia, magnesia, and titania, for example. Among these, alumina can be preferably used. By embedding the dust collection electrode in the detection device main body made of such a dielectric, it is possible to form the dust collection electrode covered with the dielectric. The particulate matter detection device has excellent heat resistance, dielectric breakdown resistance, and the like. Here, in the present embodiment, the “dielectric” refers to a substance that has a dielectric property superior to conductivity, and that behaves as an insulator against a DC voltage.

  In the present embodiment, “one end portion of the detection device main body” refers to a range from one tip portion 1c of the detection device main body to a position corresponding to 50% of the total length of the detection device main body 1. Say. The term “the other end of the detection device main body” refers to a range from the other tip portion 1d of the detection device main body to a position corresponding to 50% of the total length of the detection device main body 1. The one end portion of the detection device main body is preferably in a range from one tip portion 1c of the detection device main body to a position corresponding to 40% of the total length of the detection device main body 1, and more preferably. Is a range corresponding to a length of 30%. The other end of the detection device main body is preferably in a range from the other tip portion 1d of the detection device main body to a position corresponding to 40% of the total length of the detection device main body 1, and more preferably. Is a range corresponding to a length of 30%. The position between one end 1a and the other end 1b of the detection device main body 1 is a portion obtained by removing the range of the one end 1a and the other end 1b from the detection device main body 1. become.

  As shown in FIG. 1A to FIG. 1D, in the particulate matter detection device 100 of the present embodiment, the detection device main body 1 is formed long in one direction, and the length in the longitudinal direction is not particularly limited. It is preferable that the length is such that the particulate matter in the exhaust gas can be efficiently sampled when inserted into the exhaust gas.

  The thickness of the detection device main body 1 (the length in the direction (thickness direction) perpendicular to both the “longitudinal direction of the detection device main body” and the “gas flow direction”) is not particularly limited. About 5 to 3 mm is preferable. Here, the “thickness of the detection device main body 1” refers to the thickness of the thickest portion in the thickness direction. Moreover, the length in the flow direction (the length in the gas flow direction) when the gas flows through the through hole 2 of the detection device main body 1 is not particularly limited, but is preferably about 2 to 20 mm, for example. And it is preferable that the longitudinal direction length of the detection apparatus main body 1 is 10 to 100 times the thickness of the detection apparatus main body 1, and is 3 to 100 times the length of the detection apparatus main body 1 in the gas flow direction. Is preferred.

  As shown in FIGS. 1A to 1D, the shape of the detection device main body 1 may be a plate having a rectangular cross-section perpendicular to the longitudinal direction, or the cross-sectional shape may be a rod shape such as a circle or an ellipse. Other shapes may be used as long as the shape is long in one direction.

  In the particulate matter detection device 100 of the present embodiment, the shape and size of the through-hole 2 are not particularly limited as long as the exhaust gas can be passed through and the amount of particulate matter can be measured. For example, the length of the through hole 2 in the longitudinal direction of the detection device main body is preferably about 2 to 20 mm, and the width of the portion of the through hole 2 sandwiched between the dust collection electrodes 11 and 12 (the longitudinal direction of the detection device main body, The length in a direction perpendicular to both the gas flow direction and the gas flow direction is preferably about 3 to 30 mm.

  By setting the size of the through-hole 2 within the above range, exhaust gas containing particulate matter can be sufficiently circulated in the through-hole 2, and further, it is effective for charging the particulate matter in the through-hole 2. It is possible to cause an electrical discharge.

  Moreover, as a shape of the through-hole 2, it is preferable that at least one of the inlet part into which the fluid flows in, and the outlet part from which the fluid flows out of the through-hole 2 are expanded. Since at least one of the inlet portion into which the fluid flows and the outlet portion from which the fluid flows out of the through-hole 2 is expanded, the particulate matter detection device penetrates the exhaust gas flowing through the pipe more efficiently. It is possible to flow into the hole (when the inlet portion is expanded) or to flow out (when the outlet portion is expanded).

  In another embodiment of the particulate matter detection device of the present invention shown in FIG. 10 (particulate matter detection device 400), only the inlet portion 2a into which the fluid flows in the through hole 2 is expanded, and the expanded portion 2b. Is formed. Further, in the particulate matter detection device 400 shown in FIG. 10, the through hole 2 is expanded so as to expand in the longitudinal direction of the detection device main body 1, but extends so as to extend in the thickness direction of the detection device main body 1. It may be expanded. 10 shows another embodiment of the particulate matter detection device of the present invention, and is a schematic diagram showing a cross section of one embodiment (particulate matter detection device 100) of the particulate matter detection device of the present invention shown in FIG. FIG.

  The expanded width of the expanded portion 2b (the width of the most distal portion of the through hole 2 in the gas flow direction) W1 is preferably 2 to 200% with respect to the width W2 of the unextended portion of the through hole 2. . Further, the depth L1 of the expanded portion 2b in the gas flow direction of the through hole 2 (depth of the expanded portion) L1 is 5 to 30% of the length L2 of the through hole 2 of the detection device body 1 in the gas flow direction. preferable.

  As shown in FIGS. 11A and 11B, in another embodiment of the particulate matter detection device (particulate matter detection device 500) of the present invention, the cross-sectional shape perpendicular to the central axis of the detection device body 1 has a through-hole. In the penetrating direction 2, it is preferable that the shape gradually becomes thicker from one end side toward the central part, is thickest at the central part, and further becomes gradually thinner toward the other end side. By making the shape of the detector main body in this way, the flow of exhaust gas in the pipe is good when the gas flow direction of the through hole is matched (parallel) to the flow direction of the exhaust gas in the pipe. Can be.

  The “center portion” of the particulate matter detection device (detection device main body) in the penetration direction of the through hole is the center of the particulate matter detection device when the length in the penetration direction of the through hole is divided into three equal parts. Means a “one-third range” located. Therefore, when the phrase “thickest in the central part in the penetration direction of the through-hole of the particulate matter detection device” is used, the thickest part is located in the “one-third range located in the central part”. means. Here, FIG. 11A is a schematic view showing another embodiment of the particulate matter detection device of the present invention, showing a cross section perpendicular to the central axis and including a through hole, and FIG. 11B is a particulate shape of the present invention. It is a schematic diagram which shows the cross section which does not contain a through-hole orthogonal to the central axis which shows other embodiment of a substance detection apparatus.

  In the particulate matter detection device of the present embodiment, the detection device main body 1 is preferably formed by laminating a plurality of tape-shaped ceramics (ceramic sheets). This makes it possible to produce a particulate matter detection device by laminating a plurality of tape-shaped ceramics with each electrode, wiring, etc. sandwiched between them, so that the particulate matter detection device of the present embodiment is efficient. Can be manufactured.

[1-1b] Measurement electrode:
The measurement electrodes are arranged at least one pair on the inner surface or inside of one wall forming the through-hole, and are generated by electrically adsorbing particulate matter on the wall surface of the through-hole by the dust collecting electrode. It is an electrode for measuring a change in electrical characteristics of a wall forming a hole.

  The shape of the measurement electrode is not particularly limited as long as it can measure the change in the electrical characteristics of the wall forming the through-hole as described above. A preferred example is a shape branched into two. By configuring in this way, more accurate measurement can be performed.

  The thickness of a measurement electrode is not specifically limited, For example, it is preferable that it is 5-30 micrometers. Examples of the material of the measurement electrode include platinum (Pt), molybdenum (Mo), tungsten (W), and the like.

  A pair of measurement electrode wires each extending toward the other end of the detection device main body is electrically connected to the measurement electrodes. The width of each measurement electrode wiring is not particularly limited, and is preferably about 0.2 to 1 mm, for example. Moreover, the thickness of the measurement electrode wiring is not particularly limited, and is preferably about 5 to 30 μm, for example. Examples of the material for the measurement electrode wiring include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. As described above, the measurement electrode wiring is configured such that no current flows between the measurement electrode wirings and between other electrodes and wirings by the shield electrode.

  As shown in FIGS. 1A to 1D, the pair of measurement electrodes 15 and 16 of the particulate matter detection device 100 according to the present embodiment are connected to the other end 1 b of the detection device main body 1, respectively. 15a and 16a.

  A portion where the through hole 2 is disposed (that is, one end portion 1a) by disposing the takeout terminals 15a and 16a of the pair of measurement electrodes 15 and 16 at the other end portion 1b of the detection device main body 1. Since it is possible to increase the distance between the terminal 15a and the extraction terminals 15a and 16a, only one end 1a where the through-hole 2 or the like is disposed is inserted into a pipe through which high-temperature exhaust gas flows, and the extraction terminals 15a and 16a. It is possible to put the other end 1b side where the is disposed out of the pipe. If the extraction terminals 15a and 16a are heated to a high temperature, the detection accuracy of the particulate matter may be lowered, and it may be difficult to perform stable detection, or when used for a long period of time, the electrical terminal and the harness for connecting to the outside Since contact failure may occur and measurement may become impossible, by taking out the extraction terminals 15a and 16a out of the piping and not exposing them to high temperatures, highly accurate and stable detection of particulate matter is possible. Can be done.

  As shown in FIG. 1B, the takeout terminals 15a and 16a disposed on the other end 1b of the detection device main body 1 are arranged on the side surface of the other end 1b of the detection device main body 1 so as to extend in the longitudinal direction. It is preferable that In FIG. 1B, the width of the other end 1b of the detection apparatus main body 1 is narrow, but the width of the other end 1b may be narrowed in this way. It does not have to be. The shapes and sizes of the takeout terminals 15a and 16a are not particularly limited. For example, a strip shape having a width of 0.1 to 2.0 mm and a length of 0.5 to 20 mm is preferable. As the material of the extraction terminals 15a and 16a, nickel (Ni), platinum (Pt), chromium (Cr), tungsten (W), molybdenum (Mo), aluminum (Al), gold (Au), silver (Ag), Examples include copper (Cu).

[1-1c] Dust collecting electrode:
The dust collecting electrode is embedded in each of the opposing walls that form the through-hole and outside the wall that forms the through-hole rather than the embedded position of the pair of measurement electrodes, and forms a dielectric that constitutes the detection device body. It is an electrode covered with a body. By applying a predetermined voltage between the dust collecting electrodes 11 and 12, discharge can be caused in the through hole 2.

  The shape of the dust collecting electrode is not particularly limited as long as it is embedded in the wall forming the through hole and can discharge in the through hole 2. In the particulate matter detection device of the present embodiment, one electrode of the dust collecting electrode is opposite to the wall on which the measurement electrodes 15 and 16 are disposed and the opposite wall across the through hole 2 as shown in FIG. (See FIG. 2), a high-voltage dust collecting electrode 11 to which a high voltage is applied, and the other electrode of the dust collecting electrode, as shown in FIG. This is a grounded dust collecting electrode 12 that is grounded (see FIG. 2) and is disposed inside the wall on the same side as the wall on which 16 is disposed. The thickness of each dust collection electrode is not specifically limited, For example, it is preferable that it is 5-30 micrometers. Examples of the material for the dust collection electrode include platinum (Pt), molybdenum (Mo), tungsten (W), and the like.

  The shape and size of the dust collecting electrodes 11 and 12 are not particularly limited as long as it can cause discharge in the through hole 2. For example, examples of the shape include a rectangle, a circle, and an oval. Moreover, it is preferable that the magnitude | size of the dust collection electrodes 11 and 12 is 70% or more of the area when the through-hole 2 is seen from the side surface, for example.

  For example, FIG. 3 shows an example in which the high-voltage dust collection electrode 11 is formed to have approximately the same size as the through hole. A wiring 11b extending in the longitudinal direction of the detection device main body 1 is connected to the high-voltage dust collecting electrode 11, and the wiring 11b is at the tip (tip on the side not connected to the electrode 11) portion of FIG. Are connected to each other by an interlayer connection (via connection). The width | variety of the wiring 11b is not specifically limited, For example, about 0.2-1 mm is preferable. Moreover, the thickness of the wiring 11b is not specifically limited, For example, about 5-30 micrometers is preferable. Examples of the material of the wiring 11b include platinum (Pt), molybdenum (Mo), tungsten (W), and the like.

  In addition, although both extraction terminals of a pair of dust collection electrodes may be disposed at the other end of the detection device main body, as shown in FIGS. 1A to 1D, a grounded dust collection electrode (grounding collection electrode) is provided. The take-out terminal 12a of the dust electrode 12) is disposed at the other end 1b of the detection device main body 1, and the take-out terminal 11a of the high-voltage dust collection electrode 11 is connected to one end 1a and the other end of the detection device main body 1. It is preferable to arrange at a position between the portion 1b. Thereby, the taking-out terminal 12a of the ground dust collecting electrode 12 and the taking-out terminal 11a of the high-voltage dust collecting electrode 11 can be arranged with a space therebetween. For this reason, in order to apply a voltage between a pair of dust collecting electrodes 11 and 12, when a voltage is applied between the extraction terminal 11a and the extraction terminal 12a, creeping discharge is generated on the surface of the detection device main body 1. Can be effectively prevented.

  In the particulate matter detection device 100 of the present embodiment, the distance between the extraction terminal 11a and the extraction terminal 12a is preferably 5 to 100 mm, and more preferably 10 to 70 mm. If it is shorter than 5 mm, a short circuit due to creeping discharge may be easily caused. On the other hand, when the detection device main body 1 of the particulate matter detection device 100 is mounted on a pipe or the like so that the takeout terminal 11a is positioned outside the pipe when the length is longer than 100 mm, it protrudes outside the pipe of the detection device main body 1. A part may become too long and it may become difficult to attach the detection apparatus main body 1 to a narrow space.

  The distance between the lead-out terminal 11a disposed at a position between the one end 1a and the other end 1b of the detection device body 1 and the through hole 2 is preferably 10 mm or more. More preferably, it is 20 mm or more. When it is shorter than 10 mm, when the particulate matter detection device 100 is attached to the pipe so that the portion of the through hole 2 is inserted into the pipe, the heat of the hot exhaust gas flowing through the pipe is taken out to the extraction terminal 11a. May be easily affected.

  The shape and size of the extraction terminal 11a of the high-voltage dust collection electrode 11 are not particularly limited. For example, it is preferably a polygonal shape such as a square having a width of 0.5 to 3 mm and a length of 0.5 to 3 mm, but may be a circle, an ellipse, a racetrack shape, or other shapes. The material of the lead terminal 11a is nickel (Ni), platinum (Pt), chromium (Cr), tungsten (W), molybdenum (Mo), aluminum (Al), gold (Au), silver (Ag), copper ( Cu), stainless steel, Kovar and the like.

  In the particulate matter detection device 100 of the present embodiment, the ground dust collection electrode 12 of the dust collection electrodes constitutes a part of the shield electrode for the measurement electrode wirings 15b and 16b (third shield electrode). . Therefore, the ground dust collecting electrode 12 includes a region where the measurement electrode wirings 15b and 16b are arranged from the inside of the wall forming the through hole 2 toward the other end 1b of the detection device main body 1. In addition, the detection device main body 1 is arranged over substantially the entire region in the longitudinal direction. The other end 1b of the detection device main body 1 is connected to the takeout terminal 12a.

  The distance between the high-voltage dust collection electrode 11 and the through hole 2 and the distance between the ground dust collection electrode 12 and the through hole 2 are preferably 50 to 500 μm, and more preferably 100 to 300 μm. preferable. By setting it as such a range, an electric discharge can be effectively produced in a through-hole. The distance between each dust collection electrode 11 and 12 and the through-hole 2 is the thickness of the portion of the dielectric covering each dust collection electrode 11 and 12 that faces the through-hole 2.

  The type of discharge generated by the dust collecting electrode is preferably one selected from the group consisting of silent discharge, streamer discharge, and corona discharge. In order to generate such a discharge, it is preferable that the particulate matter detection device 100 according to the present embodiment further includes a power source for discharge connected to the extraction terminals 11a and 12a. As the power source for discharging, a high voltage AC power source, a DC power source or the like is preferable. Moreover, as a voltage applied in order to discharge, voltages, such as pulse voltage and alternating current voltages, such as a rectangular wave, are preferable. Moreover, as conditions of the voltage to apply, although it changes with gaps (distance between a pair of dust collection electrodes) and gas temperature, 50-200 kV / cm is preferable. Moreover, 0.1-10 W is preferable for the electric power when a voltage is applied.

  The particulate matter detection device 100 of the present embodiment causes discharge in the through hole 2 when the particulate matter contained in the fluid (that is, exhaust gas) flowing into the through hole 2 is not charged. The particulate matter is charged and the charged particulate matter is electrically adsorbed on the wall surface of the through hole 2. If the particulate matter contained in the fluid flowing into the through-hole 2 is already charged before flowing into the through-hole 2, there is no need to recharge by the discharge in the through-hole 2. Therefore, the charged particulate matter is electrically adsorbed on the wall surface of the through hole 2 without causing a discharge in the through hole 2.

  As described above, when a discharge occurs in the through-hole 2 to charge the particulate matter, the charged particulate matter has an opposite polarity to the polarity of the charged particulate matter during the discharge. It is electrically attracted to the dust collecting electrode side and is adsorbed on the wall surface. On the other hand, when the particulate matter is charged before flowing into the through-hole 2, the charged particulate matter is charged by applying a voltage under a predetermined condition between the dust collecting electrodes 11 and 12. So as to be electrically attracted to the dust collecting electrode side having a polarity opposite to the polarity of. Here, when the particulate matter is charged before flowing into the through-hole 2, the condition of the voltage applied between the dust collecting electrodes 11 and 12 is preferably 4 to 40 kV / cm.

[1-1d] Shield electrode:
As described above, the shield electrode suppresses the influence of the parasitic capacitance that occurs between each measurement electrode wiring or between each measurement electrode wiring and other wirings, etc. It is an electrode for performing.

  The thickness of a shield electrode is not specifically limited, For example, it is preferable that it is 5-30 micrometers. Examples of the material for the shield electrode include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. Note that the shape of the shield electrode can be appropriately determined according to the shape of the measurement electrode wiring and the like as long as it is arranged so that at least a part of the current flow to be shielded can be cut off. it can.

  Since the first shield electrode 17a shown in FIG. 6 blocks current flowing between the measurement electrode wirings 15b and 16b, a pair of measurement electrode wirings on the same plane including the pair of measurement electrode wirings 15b and 16b. What is necessary is just to arrange | position in the position between 15b and 16b.

  Further, as shown in FIG. 2, the second shield electrode 17b and the third shield electrode 17c are provided between the measurement electrode wires 15b and 16b and other electrodes and wires (that is, in the thickness direction of the detection device main body). This interrupts the current flowing through the. The distance between the second shield electrode 17b and the third shield electrode 17c and the measurement electrode wirings 15b and 16b is preferably, for example, 100 to 500 μm, and more preferably 150 to 250 μm. . By setting it as such a range, a current flow can be effectively interrupted.

  Such a shield electrode also has a takeout terminal 18 for grounding the shield electrode 17 as shown in FIGS. 1A to 1D, for example. Is disposed at the other end 1b. The grounding take-out terminal 18 can also be configured in the same manner as other take-out terminals. Note that the first shield electrode 17a shown in FIG. 5 is connected to the ground extraction terminal 18 at the other end portion 1d of the detection device main body 1.

[1-1e] Heating unit:
As shown in FIGS. 2 and 7, the particulate matter detection device 100 of the present embodiment is arranged inside the detection device main body 1 along the wall surface of the through hole 2 (a wall surface parallel to the side surface of the detection device main body 1). It is preferable to further include a heating unit 13 disposed (embedded). The particulate matter adsorbed on the wall forming the through-hole 2 can be heated and oxidized by the heating unit 13, and the internal space of the through-hole 2 can be brought to a desired temperature when measuring the mass of the particulate matter. It is possible to adjust the temperature to stably measure the change in the electrical characteristics of the wall forming the through hole 2.

  Although the heating part 13 may be a wide film shape, as shown in FIG. 7, a linear metal material should be arrange | positioned so that it may wave-form and to make a U-turn at the front-end | tip part. Is preferred. By adopting such a shape, the inside of the through hole can be uniformly heated. Examples of the material of the heating unit 13 include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. The heating unit 13 is preferably embedded in the inside of the detection device main body 1 along the wall surface of the through-hole 2, but as shown in FIG. 7, not only the position where the through-hole 2 is disposed, Furthermore, it may be formed so as to extend toward the other end 1b of the detection apparatus main body 1. Thereby, the temperature difference between the inside of the through-hole and the vicinity of the through-hole can be reduced, and there is an advantage that the element (detection device main body) is not easily damaged even when rapidly heated. It is preferable that the temperature of the internal space of the through hole can be raised to 650 ° C. by the heating unit.

  In the particulate matter detection device 100 of the present embodiment shown in FIG. 2, the measurement electrodes 15, 16, and the collection electrodes are arranged inside the wall forming the through hole 2 on the side where the measurement electrodes 15, 16 are disposed. The dust electrode 12 is embedded outside the wall (that is, outside the detection device main body 1). With this configuration, the pair of measurement electrodes 15 and 16 are not affected by the heating unit 13, and it becomes easy to measure changes in the electrical characteristics of the wall forming the through hole 2.

  Further, FIG. 7 shows an example in which two heating parts 13 are formed by two wires, but there may be one heating part, or three or more pluralities. Also good. Moreover, although illustration is abbreviate | omitted, the heating part may be arrange | positioned at the wall of the both sides in which a through-hole is formed, respectively. That is, the arrangement and the number of heating units can be the arrangement and the number necessary for achieving the purpose of adjusting the temperature and oxidizing and removing the collected particulate matter.

  Further, the heating unit 13 shown in FIG. 7 is connected to the wiring 13b, and each wiring 13b is interlayer-connected to each extraction terminal 13a as shown in FIG. 1D. Similarly to the extraction terminals 15a and 16a of the measurement electrodes 15 and 16, the extraction terminal 13a of the heating unit 13 is also used to avoid the influence of heat when the one end 1a side of the detection device body 1 is heated. It is preferable that the other end 1b of the detection device main body 1 is disposed. In FIG. 1D, the four extraction terminals 13a are arranged on the other side surface side of the detection apparatus main body 1 so that four are arranged, but the arrangement of the extraction terminals 13a is limited to such an arrangement. It is not a thing.

  When the heating unit 13 is linear, the width of the line is not particularly limited, and is preferably about 0.05 to 1 mm, for example. Moreover, the thickness of the heating part 13 is not specifically limited, For example, about 5-30 micrometers is preferable. The width | variety of the wiring 13b is not specifically limited, For example, about 0.7-4 mm is preferable. Moreover, the thickness of the wiring 13b is not specifically limited, For example, about 5-30 micrometers is preferable. The width | variety of the taking-out terminal 13a corresponding to the heating part 13 is not specifically limited, For example, about 0.1-2 mm is preferable. Moreover, the thickness of the extraction terminal 13a is not specifically limited, For example, about 5-1000 micrometers is preferable. As materials for the wiring 13b and the extraction terminal 13a, nickel (Ni), platinum (Pt), chromium (Cr), tungsten (W), molybdenum (Mo), aluminum (Al), gold (Au), silver (Ag) , Copper (Cu), stainless steel, Kovar and the like.

  Further, the particulate matter detection device 100 of the present embodiment applies a voltage to the pair of dust collecting electrodes 11 and 12 by applying a voltage to the particulate matter adsorbed on the wall or the measurement electrode forming the through hole. It is also possible to cause oxidative removal by causing a discharge (that is, a discharge under conditions different from the charge of the particulate matter). As conditions for causing discharge when oxidizing and removing particulate matter, the electric field strength is 10 to 200 kV / cm, and the energy input is 0.05 to 10 J / with respect to the material to be treated (particulate matter). It is preferable that it is microgram.

  It is preferable that the particulate matter detection device 100 of the present embodiment further includes a heating power source connected to the takeout terminal 13a of the heating unit 13. Examples of the power source for heating include a constant current power source.

[1-1f] Other components:
The particulate matter detection device of the present embodiment is a measurement unit for measuring a change in electrical characteristics between a pair of measurement electrodes, and for electrically connecting the measurement unit and a pair of measurement electrode wires. You may further provide a pair of measurement part connection wiring. In addition, as described above, a power source for discharge, a power source for the heating unit, and wiring for electrical connection therewith may be further provided.

[1-2] Manufacturing method of particulate matter detection device:
Next, a method for manufacturing the particulate matter detection device 100 according to the present embodiment will be described using a method for manufacturing the particulate matter detection device 100 shown in FIGS. 1A to 1D as an example.

[1-2a] Preparation of molding raw material:
First, a forming raw material for manufacturing the detection device main body 1 is prepared. Specifically, for example, at least one ceramic raw material (dielectric raw material) selected from the group consisting of alumina, cordierite forming raw material, mullite, glass, zirconia, magnesia, and titania, and other used as a forming raw material The ingredients are mixed to prepare a slurry-like forming raw material. The ceramic raw material (dielectric raw material) is preferably the above raw material, but is not limited thereto. As other raw materials, it is preferable to use a binder, a plasticizer, a dispersant, a dispersion medium and the like.

  The binder is not particularly limited, and either an aqueous binder or a non-aqueous binder may be used. As the aqueous binder, methylcellulose, polyvinyl alcohol, polyethylene oxide, or the like can be suitably used. As the non-aqueous binder, polyvinyl butyral, Acrylic resins, polyethylene, polypropylene, and the like can be suitably used. Examples of the acrylic resin include (meth) acrylic resin, (meth) acrylic acid ester copolymer, acrylic acid ester-methacrylic acid ester copolymer, and the like.

  The addition amount of the binder is preferably 3 to 20 parts by mass, and more preferably 6 to 17 parts by mass with respect to 100 parts by mass of the dielectric material. By setting it as such binder content, it becomes possible to prevent generation | occurrence | production of a crack etc., when shape | molding a slurry-like shaping | molding raw material and shape | molding a green sheet, and when drying and baking.

  As the plasticizer, glycerin, polyethylene glycol, dibutyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, or the like can be used.

  The addition amount of the plasticizer is preferably 30 to 70 parts by mass and more preferably 45 to 55 parts by mass with respect to 100 parts by mass of the binder. When the amount is more than 70 parts by mass, the green sheet becomes too soft and may be easily deformed in the process of processing the sheet. When the amount is less than 30 parts by mass, the green sheet becomes too hard and cracks are generated only by bending. Handling characteristics may deteriorate.

  As the dispersant, an anionic surfactant, a wax emulsion, pyridine, or the like can be used in an aqueous system, and a fatty acid, a phosphate ester, a synthetic surfactant, or the like can be used in a non-aqueous system.

  The dispersant is preferably 0.5 to 3 parts by mass, and more preferably 1 to 2 parts by mass with respect to 100 parts by mass of the dielectric material. If the amount is less than 0.5 parts by mass, the dispersibility of the dielectric material may be lowered, and a crack or the like may occur in the green sheet. When the amount is more than 3 parts by mass, the dispersibility of the dielectric material is not changed, and impurities during firing are increased.

  As the dispersion medium, water or the like can be used. The dispersion medium is preferably 50 to 200 parts by mass, and more preferably 75 to 150 parts by mass with respect to 100 parts by mass of the dielectric material.

  The above raw materials are sufficiently mixed using an alumina pot and alumina cobblestone to produce a slurry-like forming raw material for producing a green sheet. Further, these materials may be manufactured by ball mill mixing with a monoball.

  Next, the resulting green sheet-forming slurry-like forming raw material is stirred and degassed under reduced pressure, and further prepared to have a predetermined viscosity. The viscosity of the slurry-like molding material obtained in the preparation of the molding material is preferably 2.0 to 6.0 Pa · s, more preferably 3.0 to 5.0 Pa · s, 3.5 It is especially preferable that it is -4.5 Pa.s. It is preferable to adjust the viscosity range in this manner because the slurry can be easily formed into a sheet shape. If the slurry viscosity is too high or too low, molding may be difficult. The viscosity of the slurry is a value measured with a B-type viscometer.

[1-2b] Molding process:
Next, the slurry-like forming raw material obtained by the above method is formed into a tape shape to produce a green sheet that is long in one direction. The forming method is not particularly limited as long as the forming raw material can be formed into a sheet shape to form a green sheet, and a known method such as a doctor blade method, a press forming method, a rolling method, or a calendar roll method is used. Can do. At this time, a green sheet for forming a through hole is prepared so that the through hole is formed when the green sheets are stacked. The thickness of the green sheet to be manufactured is preferably 50 to 800 μm.

  Each electrode, wiring, heating unit, and takeout terminal are disposed on the surface of the obtained green sheet. When producing the particulate matter detection device 100 shown in FIGS. 1A to 1D, as shown in FIGS. 3 to 7, each electrode, wiring, heating unit, and extraction terminal are arranged at predetermined positions. As described above, it is preferable to print each electrode, wiring, heating unit, and takeout terminal at a corresponding position on the green sheet.

  The conductor paste for forming (printing) each electrode, wiring, heating part, and takeout terminal is made of gold, silver, platinum, nickel, according to the respective materials necessary for forming each electrode, wiring, etc. It can be prepared by adding a solvent such as binder and terpineol to a powder containing at least one selected from the group consisting of molybdenum and tungsten, and sufficiently kneading using a triroll mill or the like. Each conductor paste containing the material necessary for forming each electrode, wiring, etc. formed in this way is printed on the surface of the green sheet using screen printing or the like, and each electrode, wiring having a predetermined shape is printed. The heating part and the takeout terminal are formed.

  More specifically, a plurality of green sheets are produced, and two of the green sheets are provided with a dust collecting electrode on one side of each, and are necessary for each arranged dust collecting electrode. Accordingly, wirings are arranged in accordance with the two, and two dust collecting electrode-arranged green sheets are formed.

  Further, with respect to the other one green sheet, a pair of measurement electrodes is disposed at a position where the through hole of the detection apparatus main body is formed to form a measurement electrode-arranged green sheet. At this time, a pair of measurement electrode wires extending from the respective measurement electrodes toward the other end of the main body of the detection device are disposed, and further, a first shield electrode is provided at a position between the pair of measurement electrode wires. Is disposed.

  Furthermore, when it overlaps with the measurement electrode-arranged green sheet, a cut portion serving as a through hole is formed at a position overlapping the measurement electrode to form a cut portion forming green sheet. At this time, the second shield electrode is disposed at a position overlapping the measurement electrode wiring when the measurement electrode is disposed on the green sheet. The second shield electrode may be prepared using another green sheet without being disposed on the cut portion forming green sheet, but the second shield electrode is disposed on the cut portion forming green sheet. Accordingly, the number of green sheets to be used can be reduced, and the particulate matter detection device can be made thinner.

  Furthermore, about another one other green sheet, a heating part is arrange | positioned in the position where a through-hole is formed at least, and a heating part arrangement | positioning green sheet is formed. The heating unit-arranged green sheet is also provided with a wiring extending toward the other end of the detection device main body.

  After that, each of the two dust collecting electrode-equipped green sheets is overlaid with a green sheet on which no other electrodes are arranged, and the dust collecting electrode and wiring are covered with the green sheet, and the dust collecting electrode-embedded green sheet And Then, the two dust collecting electrode-embedded green sheets are laminated so that the measurement electrode-arranged green sheet and the cutting part forming green sheet are sandwiched, and the heating part-arranged green sheet is further laminated on the outer side of the two dust collecting electrodes. A green sheet laminate is formed with the cut portion sandwiched between the electrodes.

  The plurality of green sheets may be stacked at the same time. For example, a dust collecting electrode-embedded green sheet may be first manufactured and then stacked with another green sheet. Lamination is preferably performed while applying pressure.

  In the method for manufacturing the particulate matter detection device of the present invention, a desired electrode or the like is provided on a plurality of green sheets, the green sheets provided with the electrodes or the like are stacked, dried and fired to detect the particulate matter. Since the device is manufactured, the particulate matter detection device of the present invention can be efficiently manufactured.

[1-2c] Firing:
Next, the green sheet laminate is dried and fired to obtain a particulate matter detection device. More specifically, the obtained green sheet laminate is dried at 60 to 150 ° C. and fired at 1200 to 1600 ° C. to produce a particulate matter detection device. When a green sheet contains an organic binder, it is preferable to degrease at 400-800 degreeC before baking.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of molding raw materials)
Alumina is used as a dielectric material, polyvinyl butyral as a binder, di-2-ethylhexyl phthalate as a plasticizer, sorbitan trioleate as a dispersant, and an organic solvent (xylene, butanol = 6: 4 (mass) These were put in an alumina pot and mixed to produce a slurry-like forming raw material for producing a green sheet. The amount of each raw material used was 7 parts by mass of binder, 3.5 parts by mass of plasticizer, 1.5 parts by mass of dispersant, and 100 parts by mass of organic solvent with respect to 100 parts by mass of alumina.

  Next, the obtained slurry-like forming raw material for green sheet production was stirred under reduced pressure to defoam, and prepared to have a viscosity of 4 Pa · s. The viscosity of the slurry was measured with a B-type viscometer.

(Molding)
Next, the slurry-like forming raw material obtained by the above method was formed into a sheet using a doctor blade method. At this time, a cut portion forming green sheet was also prepared so that a through hole was formed when the green sheets were laminated. The thickness of the green sheet was set to 50 μm for the green sheet on which the measurement electrodes are arranged, and 250 μm for the other green sheets.

  As shown in FIGS. 2 to 7, each electrode (measurement electrode, shield electrode, and dust collecting electrode), a heating unit, each wiring, and each extraction terminal were formed on the surface of the obtained green sheet. Conductive paste for forming each electrode to be disposed, ground electrode, wiring, and attachment terminal is platinum powder, 2-ethylhexanol as a solvent, polyvinyl butyral as a binder, di-2-ethylhexyl phthalate as a plasticizer, It was prepared by adding sorbitan trioleate as a dispersing agent, alumina as a co-fabric of green sheets, glass frit as a sintering aid, and kneading thoroughly using a mill and triroll mill (by mass ratio, platinum: alumina : Glass frit: 2-ethylhexanol: polyvinyl butyral: di-2-ethylhexyl phthalate: sorbitan trioleate = 80: 15: 5: 50: 7: 3.5: 1).

  In addition, the conductive paste for forming the heating part is made of platinum powder, 2-ethylhexanol as a solvent, polyvinyl butyral as a binder, di-2-ethylhexyl phthalate as a plasticizer, sorbitan trioleate as a dispersant, green sheet Prepared by adding alumina as a co-fabric and glass frit as a sintering aid and thoroughly kneading using a rake machine and a tri-roll mill (by mass ratio, platinum: alumina: glass frit: 2-ethylhexanol: polyvinyl Butyral: di-2-ethylhexyl phthalate: sorbitan trioleate = 80: 15: 5: 50: 7: 3.5: 1).

  The conductor paste thus formed was printed on the surface of the green sheet using screen printing to form electrodes having a predetermined shape. Specifically, for two green sheets of the plurality of green sheets, a dust collection electrode is disposed on one surface of each of the green sheets, and a wiring extending toward the other end is disposed for the high voltage dust collection electrode. And two dust collecting electrode-arranged green sheets were formed.

  Further, a pair of comb-shaped measurement electrodes was formed in a portion where a through hole was to be formed in a green sheet having a thickness of 50 μm. The pair of comb-shaped measurement electrodes are spaced so that the pitch between the comb teeth is 0.35 mm (the clearance of the comb teeth is 0.15 mm and the width of each comb tooth is 0.20 mm). They were placed opposite each other so as to mesh with each other. In addition, about the measurement electrode, a pair of measurement electrode wiring wiring extended toward the other edge part was arrange | positioned, and also the 1st shield electrode was arrange | positioned in the position between a pair of measurement electrode wiring wiring. Note that the widths of the measurement electrodes and the measurement electrode wiring lines were each 0.2 mm.

  Furthermore, about another one green sheet, when it overlap | superposed with the measurement electrode arrangement | positioning green sheet, the cut part used as a through-hole was formed in the position which overlaps with a measurement electrode, and the cut part formation green sheet was formed. In addition, the second shield electrode was also disposed on the cut portion forming green sheet so as to overlap with the measurement electrode wiring when it was overlapped with the above-described measurement electrode-arranged green sheet.

  Further, for another one of the green sheets, a heating part is formed at a position overlapping with a cutting part that becomes a through hole when overlapped with the cutting part forming green sheet, and the wiring extends from the heating part toward the other end. To form a heating part forming green sheet.

  Then, the dust collecting electrode-embedded green sheet is formed in such a state that the dust collecting electrode and the wiring are covered with the green sheet by overlapping the green sheet on which the other electrodes are not disposed on each of the two dust collecting electrode-equipped green sheets. In addition, the measurement electrode placement green sheet and the cutting part forming green sheet are stacked between the two dust collecting electrode embedded green sheets, and the heating part forming green sheet is positioned outside the dust collecting electrode embedded green sheet. Thus, a green sheet laminate was formed in which the cut portion was sandwiched between two dust collecting electrodes and the measurement electrode was sandwiched between two wires. Each wiring and the extraction terminal corresponding to each wiring were interlayer connected (via connection) by a method of embedding a conductor paste.

  Lamination of the green sheets was performed by pressure lamination using a uniaxial press capable of heating the green sheets to obtain an unfired body of the particulate matter detection device composed of the green sheet laminate.

(Baking)
The obtained green sheet laminate (unfired body of the particulate matter detection device) was dried at 120 ° C. and fired at 1500 ° C. to produce a particulate matter detection device. The obtained particulate matter detection device had a shape of a rectangular parallelepiped of 0.625 cm × 0.205 cm × 7 cm with the other end narrowed in two stages as shown in FIG. 1B. The width of the portion from the other end to 12 cm from the other end (the first step) is 4.25 cm, and the portion from the first step to the other end by 16 cm from the other end (two The width of the step portion) was 6.24 cm.

(Discharge power supply)
As a power source for discharge, a pulse power source and a DC power source were used and connected to an electrode extraction terminal.

(Measurement part)
As a measurement unit for measuring the impedance between the measurement electrodes, an impedance analyzer manufactured by Agilent Technologies was used and connected to the extraction terminal of the measurement electrode. As shown in FIG. 9, the measurement unit wiring shield electrode 54 is disposed in the range of the measurement unit wiring 52 through which the current flowing from the measurement electrode passes to the entrance side of the resistor 56 and the operational amplifier 55, as shown in FIG. To prevent a large current from flowing from the outside. In addition, the shield electrode for measurement part wiring was formed with the copper mesh wire, and was electrically connected to the ground terminal.

(Measurement unit connection wiring)
In the measurement unit connection wiring that connects the measurement unit and the extraction terminal of the measurement electrode, the wiring input to the measurement unit was covered (shielded) with the shield electrode for connection wiring. In addition, each taking-out terminal of the detection apparatus main body, the measurement part connection wiring, and the measurement part were electrically connected as shown in FIG. Here, FIG. 12 is a schematic diagram schematically illustrating the configuration of the detection apparatus main body according to the first embodiment. In addition, about the thing comprised similarly to each element of the particulate matter detection apparatus shown in FIGS. 3-9, the same code | symbol is attached | subjected and description is abbreviate | omitted. In FIG. 12, reference numeral 65 indicates a wiring that electrically connects the dust collection electrode 11 and the measurement unit 50, and reference numeral 66 indicates an electrical connection between the second dust collection electrode 17 and the measurement unit 50. Reference numeral 67 indicates a wiring for electrically connecting the dust collecting electrode 12 and the measurement unit 50, and reference numeral 68 indicates a wiring for electrically connecting the heating unit 13 and the measurement unit 50.

  The wiring used for the connection between each electrode and the measuring unit described above was an insulated wire using polytetrafluoroethylene (PTFE) as an insulator, and the shield electrode for the wiring in the measuring unit was a copper mesh wire. Moreover, the length of the measurement part connection wiring which connects a measurement part and the taking-out terminal of a measurement electrode was 500 mm.

(Method for measuring particulate matter)
The obtained particulate matter detection device was installed in an exhaust pipe of a diesel engine. As a diesel engine, a direct-injection diesel engine having a displacement of 2000 cc is used, the rotational speed is 1500 rpm, the torque is 24 N · m, the EGR (exhaust gas recirculation) opening degree is 50%, the exhaust gas temperature is 200 ° C., the intake air is 1.3 m ³ ( Exhaust gas was generated under operating conditions (converted to room temperature) / min. The amount of particulate matter in the exhaust gas by a smoke meter (AVL, trade name: Model 4158) was 2.0 mg / m ³ . The particulate matter was detected as follows.

  Before the particulate matter is charged and collected while generating exhaust gas from a diesel engine, the initial impedance between the pair of electrodes is measured every 10 seconds for 3 minutes, and then the particulate matter is removed for 30 seconds. Then, the charged dust collection operation is stopped, and the impedance (impedance after 30 seconds of dust collection between the pair of electrodes) (pF) is again set every 10 seconds for 3 minutes. It was measured.

  As for the initial impedance and the impedance after 30 seconds of dust collection, the average value of six measurements that were stable without any change in impedance was obtained. Then, the mass of the collected particulate matter was calculated from the difference between the initial impedance and the impedance after 30 seconds of dust collection. The calculation of the mass of the particulate matter was performed using a calibration curve prepared in advance for a change in impedance with respect to the amount of adsorption of the particulate matter. In this measurement, the particulate matter was not burned by the heater. When the particulate matter was charged and collected, the voltage applied by the high voltage power supply was set to DC 2.0 kV. The measurement result of the impedance value is shown in Table 1. Table 1 also shows the ratio of the amount of change in the impedance value after collecting for 30 seconds (the value obtained by subtracting the impedance value after collecting for 30 seconds from the initial impedance value) as the impedance change rate. Show.

  Note that an impedance analyzer manufactured by Agilent Technologies was used for the above impedance measurement. The impedance is measured with a sine wave of 2 V and 1 kHz, and the connection method in the measurement is as shown in FIG.

(Example 2)
As shown in Table 1, a particulate matter detection device having the same configuration as that of Example 1 was manufactured except that the measurement unit wiring shield electrode was not arranged in the measurement unit. The impedance was measured at. The results are shown in Table 1.

(Comparative Examples 1 and 2)
As shown in Table 1, a particulate matter detection device having the same configuration as that of Example 1 was manufactured except that the shield electrode was not arranged with respect to the measurement electrode wiring of the detection device body (Comparative Example 1). The impedance was measured by the same method as in Example 1. Further, a particulate matter detection device configured in the same manner as in Example 1 is manufactured except that the shield electrode is not disposed in all of the measurement electrode wiring, the measurement unit connection wiring, and the measurement unit (Comparative Example 2). The impedance was measured by the same method as in Example 1. The results are shown in Table 1.

  From Table 1, the particulate matter detection devices of Examples 1 and 2 have a large change in impedance value (0.41 or more), and the difference between the initial impedance value and the impedance value after 30 seconds of dust collection is clear. It turns out that it is shown. On the other hand, in Comparative Example 1 in which the shield electrode is not arranged with respect to the measurement electrode wiring, the amount of change in the impedance value is smaller than that in Example 1 due to the influence of the parasitic capacitance generated in the measurement electrode wiring. It was found that the measurement value is likely to cause an error. Further, it was found that Comparative Example 2 in which no shield electrode was arranged had a very small change in impedance value of about 1 which was a sufficient value of Example 1, and that a large error was likely to occur due to the measured value.

  It can be suitably used for immediately detecting the occurrence of a DPF defect and recognizing an abnormality of the apparatus, thereby contributing to prevention of air pollution.

1: detection device body, 1a: one end, 1b: the other end, 1c: one tip, 1d: the other tip, 2: a through hole, 2a: an entrance, 2b: an expanded portion, 11: dust collection electrode (high voltage dust collection electrode), 12: dust collection electrode (ground dust collection electrode), 11a, 12a, 13a: take-out terminal, 11b, 12b, 13b: wiring, 13: heating unit, 15, 16 : Measurement electrode, 15a, 16b: measurement electrode lead-out terminal, 15b, 16b: measurement electrode wiring, 17: shield electrode, 17a: first shield electrode (shield electrode), 17b: second shield electrode (shield electrode), 17c: Third shield electrode (shield electrode), 18: extraction terminal, 50: measurement unit, 51, 52, 53: internal wiring of measurement unit, 54: shield electrode for internal wiring of measurement unit, 55: operational amplifier, 56: resistance, 61 62: Measuring part connection wiring, 63: Shield electrode for connection wiring, 64: Shield wiring, 65, 66, 67, 68: Wiring, 100, 200, 300, 400, 500: Particulate matter detection device, W1: Expansion Width, W2: unexpanded width, L1: depth of the expanded portion, L2: length of the through hole in the gas flow direction.

Claims (12)

A detection device main body that is long in one direction in which at least one through hole is formed at one end; and
At least a pair of measurement electrodes disposed on the inner surface or inside of one wall forming the through hole; and
A pair of measurement electrode wires extending from the pair of measurement electrodes toward the other end of the detection device body, and
At least a pair of collections embedded in each of the opposing walls that form the through-holes and outside the walls that form the through-holes rather than the embedded positions of the pair of measurement electrodes and covered with a dielectric. A dust electrode;
The at least one measurement electrode wiring of the pair of measurement electrode wirings is disposed with a dielectric interposed therebetween, and is grounded to block at least a part of the current flowing through the dielectric to the at least one measurement electrode wiring. A shield electrode,
The charged particulate matter contained in the fluid flowing into the through hole, or the inside of the through hole charged by a discharge generated in the through hole by applying a voltage to the pair of dust collecting electrodes It is possible to electrically adsorb the particulate matter contained in the fluid flowing into the wall to the wall surface of the through hole, and the change in the electrical characteristics of the wall forming the through hole is measured by the pair of measurements. A particulate matter detection device capable of detecting particulate matter adsorbed on the wall surface of the through hole by measuring with an electrode.   The said shield electrode is arrange | positioned in the position between said pair of measurement electrode wiring, and has a 1st shield electrode for interrupting | blocking the electric current which flows between said pair of measurement electrode wiring through the said dielectric material. Particulate matter detection device.   The second shield electrode, wherein the shield electrode is disposed at a position between the pair of measurement electrode wires and the wire connected to the high voltage dust collection electrode to which a high voltage is applied among the pair of dust collection electrodes. The particulate matter detection device according to claim 1, further comprising: a third shield electrode including a grounded dust collection electrode that is grounded from the pair of dust collection electrodes. A measurement unit for measuring a change in electrical characteristics between the pair of measurement electrodes, and a pair of measurement unit connection wirings for electrically connecting the measurement unit and the pair of measurement electrode wires. In addition,
At least one measurement unit connection wiring of the pair of measurement unit connection wirings is a grounded connection wiring shield electrode for cutting off at least part of the current flowing through the space between the pair of measurement unit connection wirings. The particulate matter detection device according to any one of claims 1 to 3, wherein the particulate matter detection device is coated with the material. A measurement unit for measuring a change in electrical characteristics between the pair of measurement electrodes, and a pair of measurement unit connection wirings for electrically connecting the measurement unit and the pair of measurement electrode wires. In addition,
The measurement unit is disposed in at least a part of the periphery of the measurement unit internal wiring electrically connected to the pair of measurement unit connection wirings, and is adjacent to the measurement unit in the measurement unit. The particulate matter detection device according to any one of claims 1 to 3, further comprising: a grounded shield electrode for measurement unit wiring for cutting off at least part of a current flowing between the wirings.   6. The particulate matter detection device according to claim 5, wherein the in-measurement-part wiring and the in-measurement-part wiring shield electrode are printed wirings arranged on an insulating printed board.   There is further provided a heating unit for temperature control, which is disposed inside the detection device main body along the wall surface of the through hole and stably measures a change in electrical characteristics of the wall forming the through hole. The particulate matter detection device according to any one of claims 1 to 6, which is provided.   The particulate matter detection device according to any one of claims 1 to 7, wherein at least one of an inlet portion into which the fluid flows and an outlet portion from which the fluid flows out of the through hole is expanded.   The cross-sectional shape perpendicular to the central axis of the detection device body gradually becomes thicker from one end side toward the central part in the penetrating direction of the through hole, thickest at the central part, and further on the other end side. The particulate matter detection device according to any one of claims 1 to 8, wherein the particulate matter detection device has a shape that gradually decreases toward the bottom.   The particulate matter adsorbed on the wall surface of the through hole can be oxidized and removed by applying a voltage to the pair of dust collecting electrodes to cause a discharge in the through hole. The particulate matter detection device according to Item.   The particulate matter detection device according to any one of claims 1 to 10, wherein the discharge that occurs in the through hole is one type selected from the group consisting of silent discharge, streamer discharge, and corona discharge.   The particulate matter detection device according to any one of claims 1 to 11, wherein the dielectric is at least one selected from the group consisting of alumina, cordierite, mullite, glass, zirconia, magnesia, and titania.

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