JP2013205028A - Particulate substance detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particulate substance detector which allows particulate substances to be detected with high sensibility and high accuracy.SOLUTION: A particulate substance detector 100 includes: a first measurement electrode 12a and a second measurement electrode 12b embedded inside the first wall 33 made of dielectric substance, with a space from each other; and a dust collection electrode 41 which is arranged at a second wall 34 opposite to the first wall 33 across a space and generates electrical field toward the first measurement electrode 12a and the second measurement electrode 12b so as to collect particulate substances contained in a measuring object gas passing between the first wall 33 and the second wall 34, at the surface of the first wall 33. The surface of the first wall 33 is provided with a groove part 35 having depth to the position where the first measurement electrode 12a and a second measurement electrode 12b are embedded, between the region 22a where the first measurement electrode is embedded and the region 22b where the second measurement electrode is embedded.

Description

  The present invention relates to a particulate matter detection device. More specifically, the present invention relates to a particulate matter detection device capable of detecting particulate matter with high sensitivity and high accuracy.

  Flue exhaust gas and diesel engine exhaust gas contain particulate matter such as soot. Hereinafter, such a particulate matter may be referred to as “PM”. PM is an abbreviation for “Particulate Matter”. Such particulate matter causes air pollution. For this reason, in order to remove the particulate matter in the exhaust gas, a filter made of ceramic or the like is widely used. Such a filter may be referred to as a “diesel particulate filter” or “DPF”. This DPF is used as an exhaust gas purification device for removing particulate matter in exhaust gas.

  Ceramic DPF can be used for a long time. On the other hand, a ceramic DPF may have defects such as cracks and melting due to thermal deterioration or the like. When such a defect occurs, there is a possibility that the particulate matter leaks from the DPF although it is in a small amount. Therefore, when a defect occurs in the DPF, 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 exhaust gas purification device.

  As a method of 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 Documents 1 to 3).

  For example, in Patent Document 1, at least one detection device main body having one through hole formed at one end and a wall that forms this through hole is embedded in a wall and covered with a dielectric. A particulate matter detection device including a pair of electrodes is disclosed. Patent Document 2 discloses a plate-like electrode having one surface coated with a dielectric, and a space through which a gas containing particulate matter flows on one surface side of the one electrode. A particulate matter detection device having two electrodes arranged in the above manner is disclosed. Patent Document 3 further includes a measurement counter electrode disposed on the surface of the convex dielectric provided on the surface of the planar dielectric with a step with respect to the planar dielectric. A particulate matter detection device is disclosed.

  In the particulate matter detection device described in Patent Document 1, particulate matter contained in a fluid is electrically adsorbed on the wall surface of the through hole of the detection device body. In the particulate matter detection device described in Patent Document 1, the mass of the particulate matter is detected by measuring a change in the electrical characteristics of the wall on which the particulate matter is adsorbed.

JP 2009-186278 A JP 2010-32488 A JP 2010-14615 A

  However, in the conventional particulate matter detection devices described in Patent Documents 1 to 3, sufficient detection sensitivity cannot be obtained, and particulate matter that can detect particulate matter with high sensitivity and high accuracy. Development of a substance detection device has been demanded.

  Specifically, the particulate matter detection devices as shown in Patent Documents 1 to 3 deposit particulate matter such as soot in the exhaust gas on the detection device body, and measure changes in electrical characteristics of the detection device body. Thus, the particulate matter is detected. A change in electrical characteristics due to the particulate matter is measured as an electrical characteristic between two or more electrodes (for example, a first measurement electrode and a second measurement electrode) provided in the detection device body.

  For example, as shown in FIG. 16, in the conventional particulate matter detection device 200, the first measurement electrode 112a and the second measurement electrode 112b are embedded in a detection device body 131 that is a dielectric. . A dust collection electrode 141 is embedded inside the detection device main body 131 that constitutes a wall opposite to the wall where the first measurement electrode 112a and the second measurement electrode 112b are embedded. By applying a voltage to the dust collection electrode 141, the particulate matter 151 in the exhaust gas G is collected on the wall in which the first measurement electrode 112a and the second measurement electrode 112b are embedded. In FIG. 16, an arrow indicated by a broken line indicates an electric field for collecting the particulate matter 151. As shown in FIG. 16, in the conventional particulate matter detection device 200, the electrical characteristics in the state where the particulate matter 151 is deposited on the surface of the wall of the detection device main body 131 are measured with the first measurement electrode 112a and the second measurement. It is measured as an electrical characteristic between the electrode 112b. In such a conventional particulate matter detection device 200, it can be said that the deposition amount and the deposition state of the particulate matter 151 are important factors that greatly affect the detection sensitivity and the detection accuracy. Here, FIG. 16 schematically shows a state in which the particulate matter in the measurement target gas is collected on the wall in which the first measurement electrode and the second measurement electrode are embedded in the conventional particulate matter detection device. It is explanatory drawing shown.

  However, as shown in FIG. 16, the first measurement electrode 112a and the second measurement electrode 112b are arranged with a space therebetween, and the electric field from the dust collecting electrode 141 is applied to the first measurement electrode 112a and the second measurement electrode. It may concentrate on each end of the electrode 112b. For this reason, the particulate matter 151 may be unevenly distributed on a part of the surface of the wall of the detection device main body 131. Thus, when the uneven distribution of the particulate matter 151 occurs, there arises a problem that the detection accuracy deteriorates. Furthermore, when the uneven distribution of the particulate matter 151 proceeds, the deposition state may be easily changed, such as the segregation state of the particulate matter 151 being unevenly distributed and deposited on the surface of the wall. May get worse.

  In addition, the change in electrical characteristics between the first measurement electrode 112a and the second measurement electrode 112b is, for example, a measurement of a change in capacitance between the first measurement electrode 112a and the second measurement electrode 112b. Is done by. At this time, in order to increase the detection sensitivity of the particulate matter detection device 200, the particulate matter 151 that causes a change in capacitance causes the first measurement electrode 112a and the second measurement electrode 112b to be linear in the shortest. It is preferable that the dust is collected at the portion connected to the. However, as shown in FIG. 16, when the particulate matter 151 is deposited so as to be concentrated on each end of the first measurement electrode 112a and the second measurement electrode 112b, the first measurement electrode 112a and the second measurement electrode Particulate matter 151 will be separated from the portion that linearly connects to 112b in the shortest distance and collected. For this reason, in the conventional particulate matter detection device 200, it is difficult to detect a change in electrical characteristics with respect to the particulate matter 151 actually collected, and sufficient detection sensitivity is not obtained. There was also a problem.

  The present invention has been made in view of the above-described problems, and provides a particulate matter detection device capable of detecting particulate matter with high sensitivity and high accuracy.

  The present invention provides the following particulate matter detection apparatus.

[1] A first measurement electrode and a second measurement electrode embedded in the first wall made of a dielectric material in a state of being spaced apart from each other, and opposed to the first wall with a space therebetween. Gas to be measured that is disposed on the second wall and passes between the first wall and the second wall by generating an electric field toward the first measurement electrode and the second measurement electrode Measuring a change in electrical characteristics between a dust collection electrode for collecting particulate matter contained in the first wall surface, and the first measurement electrode and the second measurement electrode; A particulate matter amount calculating means for obtaining an amount of the particulate matter collected by the electric field, and a region where the first measurement electrode is embedded in the surface of the first wall; Between the region where the second measurement electrode is embedded, the first measurement electrode and the second measurement electrode are Particulate matter detection device groove depth to set position is formed.

[2] Comb bone measurement in which each of the first measurement electrode and the second measurement electrode connects the plurality of comb measurement electrode portions arranged in a plane and the plurality of comb measurement electrode portions at one end thereof. Each of the plurality of comb measurement electrodes extends in a direction orthogonal to the flow direction of the measurement target gas, and the plurality of comb measurement electrodes of the first measurement electrode, The plurality of comb measurement electrode portions of the second measurement electrode are embedded in the first wall so as to be engaged with each other with a gap in the flow direction of the measurement target gas, Between each region in which the plurality of comb measurement electrode portions of one measurement electrode are embedded and each region in which the plurality of comb measurement electrode portions of the second measurement electrode are embedded, the groove portion is provided. The particulate matter detection device according to [1], wherein each is formed.

[3] The length from the surface of the first wall to the position where the first measurement electrode and the second measurement electrode are embedded in a cross section perpendicular to the flow direction of the measurement target gas is 10 to 70 μm. The particulate matter detection device according to [1] or [2].

[4] The groove is formed on the surface of the first wall such that the width of the groove is 30 to 80% with respect to the interval between the first measurement electrode and the second measurement electrode. The particulate matter detection device according to any one of [1] to [3].

[5] The dust collecting electrode is embedded in the second wall, and a position facing the position where the groove portion of the first wall is formed on the surface of the second wall. The particulate matter detection device according to any one of [1] to [4], wherein a convex portion is formed on the surface.

[6] The particulate matter detection device according to [5], wherein a shape of the convex portion in a cross section perpendicular to the direction in which the through hole extends is a square, a rectangle, a trapezoid, a triangle, a semicircle, or a semielliptical shape. .

[7] The shape of the convex portion in a cross section perpendicular to the flow direction of the measurement target gas is directed toward an intermediate portion between the first measurement electrode and the second measurement electrode embedded in the first wall. The particulate matter detection device according to [5] or [6], wherein the particulate matter detection device has a convex shape.

[8] The dust collection electrode is embedded in the second wall at a position facing the groove portion of the first wall, and the dust measurement electrode includes the first measurement electrode. The particulate matter detection device according to any one of [1] to [7], wherein a gap is formed at a position facing the region where the second measurement electrode is embedded and the region where the second measurement electrode is embedded.

[9] A plurality of comb-shaped dust collecting electrode portions, wherein the dust collecting electrodes are arranged in a plane along the extending direction of the groove portion of the first wall; The particulate matter detection device according to [8], further including a comb bone dust collecting electrode portion connected at one end.

[10] One end is provided with a detection device body that is long in one direction in which a through hole is formed, and one wall that forms the through hole of the detection device body is the first wall, The particulate matter detection device according to any one of [1] to [9], wherein the other wall disposed opposite to the one wall with the through hole interposed therebetween is the second wall.

  The particulate matter detection device according to claim 1 of the present application includes a first measurement electrode, a second measurement electrode, a dust collection electrode, and particulate matter amount calculation means. The first measurement electrode and the second measurement electrode are embedded in the first wall made of a dielectric material with a space between each other. The dust collection electrode is disposed on a second wall that is disposed to face the first wall with a space therebetween. The dust collecting electrode generates an electric field toward the first measurement electrode and the second measurement electrode, thereby removing particulate matter contained in the measurement target gas passing between the first wall and the second wall. This is an electrode for collecting dust on the surface of the first wall. The particulate matter amount calculation means is for measuring the change in electrical characteristics between the first measurement electrode and the second measurement electrode and obtaining the amount of particulate matter collected by the electric field described above. is there. And in the particulate matter detection device of the invention according to claim 1 of the present application, on the surface of the first wall, an area where the first measurement electrode is embedded and an area where the second measurement electrode is embedded In between, the groove part of the depth to the position where the 1st measurement electrode and the 2nd measurement electrode were embed | buried is formed.

  In the particulate matter detection device according to the first aspect of the present invention, the particulate matter contained in the measurement target gas is preferentially collected inside the groove portion of the first wall. In other words, by utilizing the fact that particulate matter is unevenly distributed due to the electric field generated by the dust collection electrode, a groove is provided at the uneven location, and the particulate matter is actively collected inside the groove. Let By collecting the particulate matter inside the groove part, the collected particulate matter is hardly affected by disturbance due to the flow of the measurement target gas. That is, changes in the deposition state such as the segregation state of the particulate matter are less likely to occur. In addition, by providing such a groove, the deposition position of the particulate matter is closer to the portion that connects the first measurement electrode and the second measurement electrode in the shortest straight line. It becomes easy to read the change in electrical characteristics between the two measurement electrodes. Therefore, the sensitivity of the particulate matter detection device can be improved. Thus, according to the particulate matter detection device of the invention of claim 1 of the present application, particulate matter can be detected with high sensitivity and high accuracy.

  Since the particulate matter detection device of the invention according to claim 1 of the present application can detect particulate matter with high sensitivity and high accuracy, the particulate matter detection device is installed on the downstream side of an exhaust gas treatment device such as a DPF. This is extremely effective when performing self-failure diagnosis (OBD). That is, the measurement target gas is preferably a purified exhaust gas after exhaust gas discharged from an internal combustion engine such as flue exhaust gas or diesel engine exhaust gas is once purified by DPF or the like.

  In the particulate matter detection device according to claim 2 of the present application, each of the first measurement electrode and the second measurement electrode has a plurality of comb measurement electrode portions arranged in a plane and a plurality of comb measurement electrodes. And a comb measurement electrode portion that connects the portions at one end thereof. Each of the plurality of comb-tooth measurement electrodes extends in a direction orthogonal to the flow direction of the measurement target gas. Furthermore, in the particulate matter detection device according to claim 2 of the present application, the plurality of comb measurement electrode portions of the first measurement electrode and the plurality of comb measurement electrode portions of the second measurement electrode are measured. It is embedded inside the first wall so as to be meshed with each other with a gap in the flow direction of the target gas. Then, the groove portion is between each region where the plurality of comb measurement electrode portions of the first measurement electrode are embedded and each region where the plurality of comb measurement electrode portions of the second measurement electrode are embedded. Each is formed. That is, since the plurality of grooves are formed so as to extend perpendicularly to the flow direction of the measurement target gas, the flow of the measurement target gas and the electric field from the second wall toward the first wall Due to the action, the particulate matter can be favorably collected inside the groove. In addition, by forming the first measurement electrode and the second measurement electrode in a comb-like shape as described above, the interval between the first measurement electrode and the second measurement electrode is shortened, and the particulate matter detection device The sensitivity can be further improved.

  In the particulate matter detection device according to the third aspect of the present invention, the first measurement electrode and the second measurement electrode are embedded from the surface of the first wall in the cross section perpendicular to the flow direction of the measurement target gas. Is configured to have a length of 10 to 70 μm. By comprising in this way, the thickness of the wall which covers a 1st measurement electrode and a 2nd measurement electrode becomes thin, and the detection sensitivity of a particulate matter detection apparatus can be improved more. In particular, in the particulate matter detection device of the invention according to claim 3 of the present application, a groove portion is formed in the first wall, and the particulate matter is actively collected inside the groove portion. Compared with the substance detection device, the thickness of the first wall can be made thinner.

  In the particulate matter detection device according to claim 4 of the present application, the width of the groove is 30 to 80% with respect to the interval between the first measurement electrode and the second measurement electrode. Grooves are formed on the surface. By comprising in this way, it becomes possible to ensure favorable the internal space of the groove part which can collect particulate matter. Furthermore, detection sensitivity can be further improved by narrowing the distance between the first measurement electrode and the second measurement electrode while realizing the width of the groove.

  In the particulate matter detection device according to claim 5 of the present application, the dust collection electrode is embedded in the second wall. And in the particulate matter detection device of the invention according to claim 5 of the present application, the convex portion is formed at the position facing the position where the groove portion of the first wall is formed on the surface of the second wall. Yes. By forming the convex portion as described above on the surface of the second wall, the capacitance of the second wall of the portion where the convex portion is formed is reduced, and the electric field from the dust collecting electrode is reduced. Concentrate at each end of one measurement electrode and second measurement electrode. In other words, the electric field is concentrated at the location where the groove is formed. Thereby, a larger amount of particulate matter is collected inside the groove portion of the first wall under the influence of the electric field. When the groove is formed on the first wall, the distance from the bottom surface of the groove to the surface of the second wall is from the surface of the first wall where the groove is not formed to the surface of the second wall. It may be longer than the distance. In such a case, the electric field in the portion where the groove is formed may be slightly weakened. Therefore, by forming the above-described convex portion on the surface of the second wall, a good electric field can be generated also in the portion where the groove portion is formed.

  In the particulate matter detection device according to claim 6 of the present application, the shape of the convex portion in the cross section perpendicular to the flow direction of the measurement target gas is square, rectangular, trapezoidal, triangular, semicircular, or semielliptical. is there. By forming the convex portion of such a shape, an electric field can be generated satisfactorily from the second wall in which the dust collecting electrode is embedded to the periphery of the groove portion of the first wall, and a larger amount The particulate matter can be collected inside the groove.

  In the particulate matter detection device according to claim 7 of the present application, the shape of the convex portion in the cross section perpendicular to the flow direction of the measurement target gas is the first measurement electrode embedded in the first wall and the second measurement. The shape is convex toward the intermediate part between the electrodes. As described above, by forming a convex portion that is convex toward the intermediate portion between the first measurement electrode and the second measurement electrode, the second wall (particularly, the second wall The electric field can be generated intensively around the groove portion of the first wall from the convex portion formed on the wall.

  The particulate matter detection device according to claim 8 of the present application has the following configuration. That is, the dust collection electrode is embedded in the second wall at a position facing the groove portion of the first wall, and the dust collection electrode includes a region where the first measurement electrode is embedded and A gap is formed at a location facing the region where the second measurement electrode is embedded. Thus, in the particulate matter detection device according to claim 8 of the present application, the dust collection electrode is not a single plate-like electrode, but the region where the first measurement electrode is embedded and the second measurement electrode It is a dust collection electrode in which a gap is formed at a location facing the buried region. For this reason, an electric field can be more intensively generated from the dust collection electrode to the groove portion of the first wall. In other words, since the dust collection electrode is not buried at the position facing the region where the first measurement electrode is buried and the region where the second measurement electrode is buried, the electric field from the dust collection electrode is Concentrate around the ends of one measurement electrode and the second measurement electrode. For this reason, a particulate matter can be actively collected inside a groove part.

  In the particulate matter detection device according to claim 9 of the present application, the dust collection electrode includes a plurality of comb-shaped dust collection electrode portions arranged in a plane along the extending direction of the groove portion of the first wall, and a plurality of dust collection electrode portions. And a comb bone dust collecting electrode portion for connecting the comb tooth dust collecting electrode portion at one end thereof. Thus, the dust collection electrode in which a gap is formed in a portion facing the region where the first measurement electrode is embedded and the region where the second measurement electrode is embedded is used as a comb-like electrode as described above. Thus, the wiring can be handled very easily when a voltage is applied to the dust collecting electrode.

  The particulate matter detection device according to claim 10 of the present application is provided with a detection device main body that is long in one direction and has a through-hole formed at one end. One wall forming the through hole of the detection device main body is the first wall, and the other wall disposed opposite to the one wall with the through hole interposed therebetween is the second wall. is there. A particulate matter detection device including such a detection device body is extremely effective when installed on the downstream side of an exhaust gas treatment device such as a DPF to perform self-failure diagnosis (OBD) of the exhaust gas treatment device. Inventions according to claims 1 to 10 of the present application are the inventions described in the above [1] to [10].

It is a mimetic diagram showing typically one embodiment of the particulate matter detection device of the present invention. It is a front view showing typically one embodiment of the particulate matter detection device of the present invention. It is a side view which shows one side of the particulate matter detection device shown in FIG. 2A. It is a side view which shows the other side of the particulate matter detection apparatus shown in FIG. 2A. It is a rear view of the particulate matter detection device shown in FIG. 2A. It is a schematic diagram which shows the A-A 'cross section of FIG. 2B. It is a schematic diagram which shows the G-G 'cross section of FIG. 2B. 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. In a particulate matter detection device of this embodiment, it is an explanatory view showing typically the state where particulate matter in measurement object gas is collected on the 1st wall. It is sectional drawing which shows typically other embodiment of the particulate matter detection apparatus of this invention. It is sectional drawing which shows typically other embodiment of the particulate matter detection apparatus of this invention. It is sectional drawing which shows typically other embodiment of the particulate matter detection apparatus of this invention. It is a schematic diagram which shows an example of the manufacturing method of a particulate matter detection apparatus. It is a schematic diagram which shows the other example of the manufacturing method of a particulate matter detection apparatus. It is explanatory drawing which shows typically the state by which the particulate matter in measurement object gas is collected on the wall by which the 1st measurement electrode and the 2nd measurement electrode were embed | buried in the conventional particulate matter detection apparatus.

  Hereinafter, the form for implementing this invention is demonstrated concretely. The present invention is not limited to the following embodiments. It should be understood that the present invention can be appropriately changed in design, improved, and the like based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

(1) Particulate matter detection device:
One embodiment of the particulate matter detection device of the present invention is a particulate matter detection device 100 as shown in FIG. The particulate matter detection device 100 includes a first measurement electrode 12a, a second measurement electrode 12b, a dust collection electrode 41, and a particulate matter amount calculation means 60. Here, FIG. 1 is a schematic view schematically showing one embodiment of the particulate matter detection device of the present invention.

  The particulate matter detection device 100 of this embodiment includes a first measurement electrode 12a and a second measurement electrode 12b, a dust collection electrode 41, and a particulate matter amount calculation means 60. The 1st measurement electrode 12a and the 2nd measurement electrode 12a are embed | buried in the state mutually spaced apart inside the 1st wall 33 which consists of a dielectric material. The dust collecting electrode 41 is disposed on the second wall 34 disposed to face the first wall 33 with a space therebetween. The dust collection electrode 41 generates an electric field toward the first measurement electrode 12a and the second measurement electrode 12b, thereby causing the measurement target gas G to pass between the first wall 33 and the second wall 34. It is an electrode for collecting particulate matter contained on the surface of the first wall 33. The particulate matter amount calculation means 60 measures the change in electrical characteristics between the first measurement electrode 12a and the second measurement electrode 12b, and obtains the amount of particulate matter collected by the electric field described above. belongs to. In the particulate matter detection device 100 of the present embodiment, a region 22a in which the first measurement electrode 12a is embedded and a region in which the second measurement electrode 12b is embedded on the surface of the first wall 33. The groove part 35 is formed between 22b. This groove part 35 is a groove | channel of the depth to the position where the 1st measurement electrode 12a and the 2nd measurement electrode 12b were embed | buried.

  In the particulate matter detection device 100 of the present embodiment, particulate matter contained in the measurement target gas G is preferentially collected inside the groove portion 35 of the first wall 33. That is, utilizing the fact that the particulate matter is unevenly distributed and collected by the electric field generated by the dust collecting electrode 41, the groove portion 35 is provided at the unevenly distributed portion, and the particulate matter is actively introduced into the groove portion 35. To collect dust. In FIG. 1, a broken-line arrow drawn from the second wall 34 toward the first wall 33 indicates the direction of the electric field. Thus, by collecting the particulate matter inside the groove 35, the collected particulate matter is not easily affected by the disturbance due to the flow of the measurement target gas G. That is, changes in the deposition state such as the segregation state of the particulate matter are less likely to occur. Further, by providing such a groove portion 35, the deposition position of the particulate matter is closer to the portion connecting the first measurement electrode 12a and the second measurement electrode 12b in the shortest straight line. It becomes easy to read the change in the electrical characteristics between the electrode 12a and the second measurement electrode 12b. Therefore, the sensitivity of the particulate matter detection device 100 can be improved. Thus, the particulate matter detection device 100 according to the present embodiment can detect particulate matter with high sensitivity and high accuracy.

  As shown in FIG. 1, the particulate matter detection device 100 of the present embodiment may further include a dust collection electrode power source 50 for applying a voltage to the dust collection electrode 41. The dust collection electrode power source 50 is a power source for generating an electric field from the dust collection electrode 41 toward the first measurement electrode 12a and the second measurement electrode 12b. That is, when a voltage is applied to the dust collecting electrode 41 by the dust collecting electrode power source 50, the electric field is generated.

  The particulate matter amount calculation means 60 is a calculation means for obtaining the amount of particulate matter in the particulate matter detection device 100 of the present embodiment. The method for determining the amount of particulate matter in the particulate matter detection device 100 of the present embodiment is as follows. First, particulate matter contained in the measurement target gas G passing between the first wall 33 and the second wall 34 is collected on the surface of the first wall 33 by the electric field. And the change of the electrical property between the 1st measurement electrode 12a and the 2nd measurement electrode 12b is measured. The amount of particulate matter collected on the surface of the first wall 33 is obtained from the measured “change in electrical characteristics”. The particulate matter amount calculation means 60 includes a characteristic measurement unit 61 and a particulate matter amount calculation unit 62. The characteristic measurement unit 61 measures changes in electrical characteristics between the first measurement electrode 12a and the second measurement electrode 12b. The particulate matter amount calculation unit 62 obtains the amount of particulate matter collected on the surface of the first wall 33 from the change in electrical characteristics. In the particulate matter detection device 100 according to the present embodiment, the particulate matter amount calculation means 60 calculates the concentration of particulate matter in the measurement target gas from the obtained amount of particulate matter. A portion 63 may be further provided.

  Hereinafter, a more specific configuration of the particulate matter detection device of the present embodiment will be described in more detail by taking the particulate matter detection device shown in FIGS. 2A to 2D and FIGS. 3 to 9 as an example.

  Here, FIG. 2A is a front view schematically showing one embodiment of the particulate matter detection device of the present invention. FIG. 2B is a side view showing one side surface of the particulate matter detection device shown in FIG. 2A. 2C is a side view showing the other side surface of the particulate matter detection device shown in FIG. 2A. FIG. 2D is a rear view of the particulate matter detection device shown in FIG. 2A. FIG. 3 is a schematic diagram showing the A-A ′ cross section of FIG. 2B. FIG. 4 is a schematic diagram showing a G-G ′ cross section of FIG. 2B. FIG. 5 is a schematic diagram showing a B-B ′ cross section of FIG. 3. FIG. 6 is a schematic diagram showing a C-C ′ cross section of FIG. 3. FIG. 7 is a schematic diagram showing a D-D ′ cross section of FIG. 3. FIG. 8 is a schematic diagram showing a cross section taken along line E-E ′ of FIG. 3. FIG. 9 is a schematic diagram showing the F-F ′ cross section of FIG. 3.

  As shown in FIGS. 2A to 2D, 3, and 4, the particulate matter detection device 100 of the present embodiment is a detection device body that is long in one direction and has a through-hole 32 in one end portion 31 a. 31 is provided. One wall forming the through hole 32 of the detection device main body 31 is the first wall 33 described above, and is opposed to the one wall (that is, the first wall 33) across the through hole 32. The other wall arranged is the second wall 34 described above. Accordingly, the first measurement electrode 12a and the second measurement electrode 12b are embedded in the first wall 33 forming the through hole 32 of the detection device main body 31, and are covered with a dielectric. The dust collection electrode 41 is disposed on the second wall 34 that forms the through hole 32 of the detection device main body 31. In the particulate matter detection device 100 of the present embodiment, the dust collection electrode 41 is embedded in the second wall 34. In addition, in the particulate matter detection apparatus 100 shown in FIGS. 2A to 2D and FIGS. 3 to 9, the drawing was performed with the particulate matter amount calculation means 60 (see FIG. 1) omitted.

  The detection device main body 31 constitutes a “main body in the detection portion of the particulate matter detection device 100” that is long in one direction and has a through hole 32 formed in one end portion 31a. The first measurement electrode 12a, the second measurement electrode 12b, and the dust collection electrode 41 are disposed on the opposite side of the through hole 32 (that is, the first wall 33 and the second wall 34). . The dust collection electrode 41 generates an electric field toward the first measurement electrode 12 a and the second measurement electrode 12 b, thereby converting the particulate matter contained in the measurement target gas passing through the through hole 32 to the first wall 33. It is an electrode for collecting dust on the surface. In the particulate matter detection device 100 of the present embodiment, the “direction in which the through hole 32 extends” is the “flow direction of the measurement target gas”.

  In the particulate matter detection device 100 of the present embodiment, the groove portion 35 is formed on the surface of the first wall 33 forming the through hole 32 as follows. That is, the groove 35 is formed between the region 22a in which the first measurement electrode 12a is embedded and the region 22b in which the second measurement electrode 12b is embedded. The “region 22 a in which the first measurement electrode 12 a is embedded” refers to a region 22 a in which the first measurement electrode 12 a is embedded in the direction from the second wall 34 toward the first wall 33. is there. The “region 22 b in which the second measurement electrode 12 b is embedded” refers to a region 22 a in which the second measurement electrode 12 b is embedded in the direction from the second wall 34 toward the first wall 33. is there. The groove portion 35 formed on the surface of the first wall 33 is a groove having a depth up to a position where the first measurement electrode 12a and the second measurement electrode 12b are embedded.

  In the particulate matter detection device 100 of the present embodiment, particulate matter contained in the measurement target gas is preferentially collected inside the groove portion 35 of the first wall 33. That is, utilizing the fact that the particulate matter is unevenly distributed and collected by the electric field generated by the dust collecting electrode 41, the groove portion 35 is provided at the unevenly distributed portion, and the particulate matter is actively introduced into the groove portion 35. To collect dust.

  Specifically, as shown in FIG. 10, the particulate matter 51 contained in the measurement target gas G is collected on the surface of the first wall 33 of the detection device main body 31 by the electric field generated by the dust collection electrode 41. Let At this time, since the above-described electric field concentrates at the ends of the first measurement electrode 12a and the second measurement electrode 12b, the particulate matter 51 is unevenly distributed in the vicinity of the ends of the first measurement electrode 12a and the second measurement electrode 12b. And will be collected. In the particulate matter detection device 100 of the present embodiment, the groove 35 is formed between the region 22a in which the first measurement electrode 12a is embedded and the region 22b in which the second measurement electrode 12b is embedded. A large amount of the particulate matter 51 is collected inside the groove portion 35. In addition, by collecting the particulate matter 51 inside the groove portion 35, the collected particulate matter 51 is hardly affected by disturbance due to the flow of the measurement target gas G. That is, changes in the deposition state such as the segregation state of the particulate matter 51 are less likely to occur. Further, by providing such a groove portion 35, the deposition position of the particulate matter 51 becomes closer to the portion connecting the first measurement electrode 12a and the second measurement electrode 12b in a straight line at the shortest. Therefore, it becomes easy to read the change in the electrical characteristics between the first measurement electrode 12a and the second measurement electrode 12b. Therefore, the sensitivity of the particulate matter detection device 100 can be improved. In FIG. 10, an arrow indicated by a broken line indicates an electric field for collecting the particulate matter 51. In FIG. 10, the broken line connecting the first measurement electrode 12a and the second measurement electrode 12b is the first measurement when measuring the electrical change between the first measurement electrode 12a and the second measurement electrode 12b. The detection interval between the electrode 12a and the second measurement electrode 12b is schematically shown. FIG. 10 is an explanatory view schematically showing a state in which particulate matter in the measurement target gas is collected on the first wall in the particulate matter detection device of the present embodiment.

  Thus, according to the particulate matter detection device 100 of the present embodiment, particulate matter can be detected with high sensitivity and high accuracy. In particular, the size and the like of the detection device main body 31 can be detected with high sensitivity and high accuracy while maintaining the same size as the conventional particulate matter detection device. For this reason, the particulate matter detection device 100 according to the present embodiment can achieve downsizing suitable for an internal combustion engine such as an automobile, and can reduce the manufacturing cost of the particulate matter detection device 100. The particulate matter detection device 100 of the present embodiment is extremely effective when installed on the downstream side of an exhaust gas treatment device such as a DPF and performs self-diagnosis diagnosis (OBD) of the device. That is, the measurement target gas is preferably a purified exhaust gas after exhaust gas discharged from an internal combustion engine such as flue exhaust gas or diesel engine exhaust gas is once purified by DPF or the like.

  In addition, in the particulate matter detection device of the present embodiment, as described above, particulate matter can be detected with high sensitivity and high precision, so that particulate matter having a particle diameter of nanometer order can be detected. There is also sex. That is, the particulate matter contained in the exhaust gas includes primary particles that are particulate matter having a particle diameter of the order of nanometers as described above, and secondary particles in which the primary particles are aggregated. In the conventional particulate matter detection device, the particulate matter is detected exclusively using the secondary particles as detection targets. In the particulate matter detection device of the present embodiment, the first measurement electrode and the second measurement are realized even when the primary particles are collected in the groove portion of the first wall by realizing the high sensitivity described above. It is expected that the electrical characteristics between the electrodes will change. For this reason, the particulate matter detection device of the present embodiment can be suitably used as a particulate matter detection device for detecting an extremely low concentration particulate matter such as the primary particles. In addition, the particle diameter of the particulate matter which consists of primary particles is about 10-20 nm. In addition, the particle size of the particulate material composed of secondary particles in which the primary particles are aggregated is generally 100 nm or more.

  In the particulate matter detection device of the present embodiment, the depth of the groove up to the position where the first measurement electrode and the second measurement electrode are embedded refers to the following groove. Here, the length from the surface of the first wall to the bottom surface of the groove in the cross section perpendicular to the flow direction of the measurement target gas is “a”, and the first measurement electrode and the second measurement are measured from the surface of the first wall. The length to the position where the electrode is embedded is “A”. The “length a up to the bottom surface of the groove” is 50 to 150% with respect to “the length A up to the position where the first measurement electrode and the second measurement electrode are embedded”. In the particulate matter detection device of the present embodiment, the “length a to the bottom surface of the groove” is 80 relative to “the length A to the position where the first measurement electrode and the second measurement electrode are embedded”. More preferably, it is -100%, and it is especially preferable that it is 100%. Note that, in the particulate matter detection device of the present embodiment, in the cross section perpendicular to the flow direction of the measurement target gas, on the line connecting the edge of the first measurement electrode 12a and the edge of the second measurement electrode 12b, More preferably, at least a part of the bottom surface of the groove portion 35 exists. By comprising in this way, a particulate matter can be collected in the vicinity of the part which connects the 1st measurement electrode and the 2nd measurement electrode in the shortest straight line.

  Hereinafter, the particulate matter detection device of the present embodiment will be described in more detail for each component.

(2) Configuration of particulate matter detection device:
As shown in FIGS. 2A to 2D and FIGS. 3 to 10, the particulate matter detection device 100 of this embodiment includes a first measurement electrode 12 a, a second measurement electrode 12 b, a dust collection electrode 41, and a particulate matter amount. The calculation means 60 (refer FIG. 1) is provided. The first wall 33 in which the first measurement electrode 12a and the second measurement electrode 12b are embedded, and the second wall 34 in which the dust collection electrode 41 is disposed are configured by a part of the detection device main body 31, for example. Things can be mentioned. However, the first wall 33 in which the first measurement electrode 12a and the second measurement electrode 12b are embedded, and the second wall 34 in which the dust collection electrode 41 is disposed are configured by a plate-like member made of a dielectric. It may be what was done.

(2-1) Detection device body:
The detection device main body 31 constitutes a “main body of the particulate matter detection device 100” that is long in one direction and has a through hole 32 formed in one end portion 31a. One end 31a of the detection device main body 31 where the through hole 32 is formed is made of a dielectric. A first measurement electrode 12 a and a second measurement electrode 12 b are embedded in the first wall 33 that forms the through hole 32. A dust collection electrode 41 is embedded in the second wall 34 that forms the through hole 32.

  The detection device main body is preferably a plate-like member that is long in one direction. Furthermore, it is more preferable that the through hole is formed at one end of the plate-shaped detection device main body that is long in one direction. With this configuration, when the particulate matter detection device is inserted into an automobile exhaust system or the like, the particulate matter in the measurement target gas can be efficiently sampled.

  A through hole is formed at one end of the detection device main body. The through hole is formed to extend from the front surface to the back surface of the detection device body in a direction perpendicular to the longitudinal direction of the detection device body. In the particulate matter detection device of the present embodiment, as described above, the groove is formed on the surface of the first wall that forms the through hole.

  The detection device body is preferably made of a dielectric. 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. Here, the “dielectric” refers to a substance that has a dielectric property superior to conductivity, and that behaves as an insulator against a DC voltage. The dust collecting electrode may be disposed on the surface of the second wall forming the through hole, but as described above, it is preferably embedded in the second wall made of a dielectric.

  The detection device main body is preferably made of a ceramic material containing alumina. According to the detection device body made of such a ceramic material, it is possible to generate an electric field that can favorably collect particulate matter in the through hole. The ceramic material containing alumina may contain zirconia. That is, it is preferable that the ceramic material constituting the detection device main body is mainly composed of alumina or alumina and zirconia. Here, a main component means that the mass ratio in the component is 92 mass% or more. For this reason, it is preferable that the ceramic material which comprises a detection apparatus main body is less than 8 mass% of components other than an alumina and a zirconia.

  There is no particular limitation on the thickness of the detection device main body. The thickness of the detection device body is a length in a direction perpendicular to both the “longitudinal direction of the detection device body” and the “direction in which the through hole extends”. That is, the thickness of the main body of the detection device means the length of the main body of the detection device in the direction from the second wall of the through hole toward the first wall.

  There is no particular limitation on the width of the detection device body. The width of the detection device main body is a length in a direction orthogonal to the longitudinal direction and the thickness direction of the detection device main body. That is, the width of the detection device main body means the direction in which the through hole extends.

  There is no particular limitation on the length of the through hole. The length of the through hole means the length in the longitudinal direction of the detection device main body. The through hole is formed at one end of the detection device main body. The term “one end of the detection device main body” corresponds to a length of 50% of the total length of the detection device main body 31 from one tip portion 31c of the detection device main body 31, as shown in FIGS. 2A to 2D. The range up to the position to be. The one end portion of the detection device main body 31 is preferably in a range from one tip portion 31c of the detection device main body 31 to a position corresponding to 40% of the total length of the detection device main body 31, More preferably, it is a range corresponding to a length of 30%. The term “the other end of the detection device main body” refers to a range from the other tip portion 31 d of the detection device main body 31 to a position corresponding to 50% of the total length of the detection device main body 31. The other end of the detection device main body is preferably in a range from the other tip portion 31d of the detection device main body to a position corresponding to 40% of the total length of the detection device main body 31, more preferably This is a range corresponding to a length of 30%.

  The detection device main body 31 is not particularly limited as long as it is long in one direction and can form a through hole at one end thereof. For example, as illustrated in FIGS. 2A to 2D, the shape of the detection device main body 31 may be a plate having a rectangular cross-sectional shape orthogonal to the longitudinal direction. Although not shown, the cross-sectional shape may be a bar shape such as a semicircular shape or a semi-elliptical shape.

  A first measurement electrode 12 a and a second measurement electrode 12 b are embedded in the first wall 33 that forms the through hole 32. A groove portion 35 is formed between the region 22a in which the first measurement electrode 12a is embedded and the region 22b in which the second measurement electrode 12b is embedded. The length from the surface of the first wall 33 to the position where the first measurement electrode 12a and the second measurement electrode 12b are embedded in a cross section perpendicular to the direction in which the through hole 32 extends is preferably 10 to 70 μm. . With this configuration, the detection sensitivity of the particulate matter detection device 100 can be further improved. Moreover, in the particulate matter detection device 100 of the present embodiment, the groove part 35 is formed in the first wall 33, and the particulate matter is actively collected inside the groove part 35, so that the conventional particulate matter detection is performed. Compared with the device, the thickness of the first wall can be made thinner. The length from the surface of the first wall 33 to the position where the first measurement electrode 12a and the second measurement electrode 12b are embedded is more preferably 10 to 50 μm, and more preferably 10 to 30 μm. Particularly preferred.

  Moreover, in the particulate matter detection device 100 of the present embodiment, the first wall is set so that the width of the groove portion is 30 to 80% with respect to the interval between the first measurement electrode 12a and the second measurement electrode 12b. A groove 35 is preferably formed on the surface 33. By setting the width of the groove part 35 within the above numerical range, a wider groove part 35 can be formed between the first measurement electrode 12a and the second measurement electrode 12b. Thereby, it becomes easy to collect particulate matter inside the groove 35, and the detection sensitivity can be further improved. For example, when the width of the groove is less than 30%, the space for the particulate matter to enter is reduced, and the detection sensitivity may not be sufficiently improved. In addition, when making the width | variety of a groove part into the said numerical range, detection sensitivity can be improved further by narrowing the space | interval of the 1st measurement electrode 12a and the 2nd measurement electrode 12b. That is, the detection sensitivity of the particulate matter detection device is greatly affected by the distance between the first measurement electrode 12a and the second measurement electrode 12b. Therefore, by narrowing the gap between the first measurement electrode 12a and the second measurement electrode 12b and making the width of the groove 35 wider than the gap between the first measurement electrode 12a and the second measurement electrode 12b. The detection sensitivity can be improved effectively. In addition, it is more preferable to make the width of the groove portion wider in a range that does not affect the strength of the first wall. The width of the groove is more preferably 60 to 80% with respect to the distance between the first measurement electrode 12a and the second measurement electrode 12b.

  Further, in the particulate matter detection device 100 of the present embodiment, the convex portion 36 is formed on the surface of the second wall 34 at a position facing the position where the groove portion 35 of the first wall 33 is formed. May be. Thus, by forming the convex portion 36 on the surface of the second wall 34, the electric field generated from the second wall 34 toward the first wall 33 is concentrated on the groove portion 35 of the first wall 33. Can be made. That is, by forming the convex portion 36 as described above on the surface of the second wall 34, the capacitance of the second wall 34 in the portion where the convex portion 36 is formed decreases, and the dust collecting electrode The electric field from 41 is concentrated on each end of the first measurement electrode 12a and the second measurement electrode 12b. In other words, the electric field is concentrated at the location where the groove 35 is formed. As a result, a larger amount of particulate matter is collected inside the groove portion 35 of the first wall 33 under the influence of the electric field. In addition, when the groove portion 35 is formed on the first wall 33, the distance from the bottom surface of the groove portion 35 to the surface of the second wall 34 is the first distance from the surface of the first wall 33 where the groove portion 35 is not formed. It may be longer than the distance to the surface of the second wall 34. In such a case, the electric field in the portion where the groove 35 is formed may be slightly weakened. Therefore, by forming the convex portion 36 described above on the surface of the second wall 34, a good electric field can be generated also in the portion where the groove portion 35 is formed.

  In the particulate matter detection device of the present embodiment, the shape of the above-described convex portion in a cross section perpendicular to the direction in which the through hole extends (in other words, the flow direction of the measurement target gas) is a square, a rectangle, a trapezoid, A triangular shape, a semicircular shape, or a semielliptical shape is preferable. By forming the convex portion of such a shape, an electric field can be generated satisfactorily from the second wall in which the dust collecting electrode is embedded to the periphery of the groove portion of the first wall, and a larger amount The particulate matter can be collected inside the groove. For example, FIG. 4 shows an example in which the shape of the convex portion 36 in the cross section perpendicular to the extending direction of the through hole 32 is a rectangle.

  For example, in the particulate matter detection device 101 shown in FIG. 11, the shape of the convex portion 36 in the cross section perpendicular to the extending direction of the through hole 32 is a trapezoid. Further, in the particulate matter detection device 102 shown in FIG. 12, an example in which the shape of the convex portion 36 in the cross section perpendicular to the extending direction of the through hole 32 is a triangle is shown. Furthermore, in the particulate matter detection device 103 shown in FIG. 13, an example is shown in which the shape of the convex portion 36 in the cross section perpendicular to the direction in which the through hole 32 extends is a semicircular shape. Here, FIG. 11 is a cross-sectional view schematically showing another embodiment of the particulate matter detection device of the present invention. FIG. 12 is a cross-sectional view schematically showing still another embodiment of the particulate matter detection device of the present invention. FIG. 13 is a cross-sectional view schematically showing another embodiment of the particulate matter detection device of the present invention. 11 to 13, the same components as those in the particulate matter detection device 100 shown in FIG.

  In the particulate matter detection device of the present embodiment, the shape of the convex portion in the cross section perpendicular to the direction in which the through hole extends is between the first measurement electrode and the second measurement electrode embedded in the first wall. It is more preferable that the shape is convex toward the intermediate portion. As described above, by forming a convex portion that is convex toward the intermediate portion between the first measurement electrode and the second measurement electrode, the second wall (particularly, the second wall The electric field can be generated intensively around the groove portion of the first wall from the convex portion formed on the wall.

  When a convex part is formed on the surface of the second wall, the length of the convex part from the surface of the second wall to the tip of the convex part is preferably 50 to 250 μm, and 70 to More preferably, it is 200 micrometers, and it is especially preferable that it is 80-150 micrometers. Hereinafter, the length of the convex portion from the surface of the second wall to the tip portion of the convex portion may be simply referred to as “the length to the tip portion of the convex portion”. If the length to the tip of the convex portion is too short, the effect of concentrating the electric field by the convex portion may not be sufficiently exhibited. On the other hand, if the length to the tip of the convex portion is too long, the convex portion is likely to be damaged.

  There is no particular limitation on the thickness of the first wall and the second wall forming the through hole. In each wall, electrodes used for detection of particulate matter such as a first measurement electrode, a second measurement electrode, and a dust collection electrode are embedded. For this reason, it is preferable that it is the thickness which can embed such an electrode favorably. For example, the thickness of the first wall is preferably 20 to 100 μm, more preferably 35 to 100 μm, and particularly preferably 35 to 80 μm. The thickness of the first wall is the thickness of the first wall in a portion where no groove is formed. The thickness of the second wall is preferably 50 to 500 μm, more preferably 50 to 250 μm, and particularly preferably 100 to 250 μm. The thickness of the second wall is the thickness of the second wall in the portion where the convex portion is not formed.

  The gap from the first wall to the second wall is preferably 100 to 1000 μm, more preferably 200 to 750 μm, and particularly preferably 200 to 500 μm. The above “gap from the first wall to the second wall” is the distance from the surface of the first wall where the groove is not formed to the surface of the second wall where the convex portion is not formed. is there. By setting the gap from the first wall to the second wall within the above numerical range, it is possible to collect particulate matter well on the first wall side serving as the detection surface. In the case where the first wall and the second wall are the walls that form the through holes of the detection device main body described above, the “gap from the first wall to the second wall” is the interval between the through holes. It becomes.

  The detection device main body 31 is preferably formed by laminating a plurality of tape-shaped ceramics. By comprising in this way, a detection apparatus main body can be produced by laminating each electrode, wiring and the like between a plurality of tape-shaped ceramics. For this reason, it becomes possible to manufacture a particulate matter detection device efficiently. The tape-shaped ceramic is sometimes referred to as a ceramic sheet.

(2-2) First measurement electrode and second measurement electrode:
A 1st measurement electrode and a 2nd measurement electrode are arrange | positioned inside the 1st wall which forms a through-hole. The first measurement electrode and the second measurement electrode form a pair of measurement electrodes to measure the electrical characteristics of the first wall. That is, when particulate matter is electrically collected on the surface of the first wall, the electrical characteristics of the first wall change. In the particulate matter detection device of the present embodiment, the change in electrical characteristics is measured to detect particulate matter.

  The first measurement electrode and the second measurement electrode are embedded in the first wall forming the through hole and covered with a dielectric. For example, a first measurement electrode and a second measurement electrode are disposed on a wall forming a through hole, and a thin film made of a dielectric is disposed so as to cover the surfaces of the first measurement electrode and the second measurement electrode. By this, the aspect in which the said 1st wall was formed can be mentioned as a suitable example. The thin film made of a dielectric is preferably composed mainly of alumina or alumina and zirconia. As described so far, a groove is formed between the region where the first measurement electrode is embedded and the region where the second measurement electrode is embedded.

  The first measurement electrode 12a and the second measurement electrode 12b used in the particulate matter detection device 100 of the present embodiment are not particularly limited as long as they are a pair of electrodes arranged to face each other with a space therebetween. As shown in FIG. 7, each of the first measurement electrode 12a and the second measurement electrode 12b includes a plurality of comb-tooth measurement electrode portions 13a and 13b arranged in a plane and comb measurement electrode portions 14a and 14b. A comb-like electrode is preferable. The comb measurement electrode part 14a connects a plurality of comb measurement electrode parts 13a of the first measurement electrode 12a at one end thereof. Similarly, the comb measurement electrode portion 14b connects the plurality of comb measurement electrode portions 13b of the second measurement electrode 12b at one end thereof.

  And when the 1st measurement electrode 12a and the 2nd measurement electrode 12b are the comb-tooth shaped electrodes mentioned above, the 1st measurement electrode 12a and the 2nd measurement electrode 12b are comprised as follows. Is preferred. First, each of the plurality of comb-tooth measurement electrode portions 13a and 13b is arranged to extend in a direction orthogonal to the flow direction of the measurement target gas. The plurality of comb measurement electrode portions 13a of the first measurement electrode 12a and the plurality of comb measurement electrode portions 13b of the second measurement electrode 12b are engaged with each other with a gap in the flow direction of the measurement target gas. As such, it is preferably embedded in the first wall 33. In addition, when the first measurement electrode 12a and the second measurement electrode 12b are such comb-like electrodes, the groove formed in the first wall is as follows. That is, between each area | region where the several comb measurement electrode part 13a of the 1st measurement electrode 12a is embed | buried, and each area | region where the several comb measurement electrode part 13b of the 2nd measurement electrode 12b is embed | buried. Each of the groove portions 35 is formed. By configuring in this way, in addition to the effect of the particulate matter detection device of the present embodiment described so far, the detection sensitivity of the particulate matter detection device can be further improved. That is, by using such a comb-like measurement electrode, the distance between the first measurement electrode and the second measurement electrode can be made narrower and more uniform, and the sensitivity of the particulate matter detection device can be improved. .

  There is no restriction | limiting in particular about the thickness of a 1st measurement electrode and a 2nd measurement electrode. As thickness of a 1st measurement electrode and a 2nd measurement electrode, it is preferable that it is 5-30 micrometers, for example. Moreover, platinum (Pt), molybdenum (Mo), tungsten (W) etc. can be mentioned as a material of a 1st measurement electrode and a 2nd measurement electrode.

  Hereinafter, a more preferable aspect in the case where the first measurement electrode and the second measurement electrode are comb-like electrodes will be described. Although there is no restriction | limiting in particular about the width | variety of the comb-tooth measurement electrode part which comprises a 1st measurement electrode and a 2nd measurement electrode, For example, it is preferable that it is 30-400 micrometers, and it is still more preferable that it is 50-300 micrometers, 80- Particularly preferred is 250 μm. Moreover, although there is no restriction | limiting also about the number of each comb-tooth measurement electrode part in a 1st measurement electrode and a 2nd measurement electrode, For example, it is preferable that it is at least 3 each, and it is still more preferable that it is 3-20. It is particularly preferable that the number is 4 to 8. By configuring in this way, it is possible to detect particulate matter with higher accuracy.

  The interval between the adjacent comb measurement electrode part of the first measurement electrode and the comb measurement electrode part of the second measurement electrode is preferably, for example, 30 to 400 μm, more preferably 50 to 300 μm, It is especially preferable that it is 80-250 micrometers. “The interval between the comb measurement electrode part of the adjacent first measurement electrode and the comb measurement electrode part of the second measurement electrode” refers to the distance between the comb measurement electrode part and the second measurement electrode of the adjacent first measurement electrode. It is a mutual space | interval of two comb-tooth measurement electrode parts at the time of arrange | positioning so that a comb-tooth measurement electrode part may mutually mesh | engage.

  The first measurement electrode 12a and the second measurement electrode 12b of the particulate matter detection device 100 are electrically connected to the measurement wirings 16a and 16b. The measurement wirings 16a and 16b are electrically connected to the measurement electrode lead terminals 17a and 17b arranged at the other end 31b of the detection device main body 31. The measurement electrode extraction terminals 17a and 17b are electrically connected to the particulate matter amount calculation means. In particular, the measurement electrode extraction terminals 17a and 17b are electrically connected to a characteristic measurement unit 61 (see FIG. 1) of the particulate matter amount calculation means 60 (see FIG. 1).

  By disposing the measurement electrode extraction terminals 17a and 17b at the other end 31b of the detection device main body 31, the distance between the through hole 32 and the measurement electrode extraction terminals 17a and 17b can be increased. For this reason, only one end 31a of the detection device main body 31 can be inserted into an exhaust system through which high-temperature exhaust gas flows. That is, the other end 31b side where the measurement electrode lead terminals 17a and 17b are disposed can be brought out of the exhaust system. If the measurement electrode lead terminals 17a and 17b are heated to a high temperature, the detection accuracy of the particulate matter is lowered, and it may be difficult to perform stable detection. In addition, when the particulate matter detection device is used for a long period of time, a contact failure between the measurement electrode lead-out terminal and the harness for connecting to the outside may occur and measurement may become impossible.

  As shown in FIG. 2B, the measurement electrode lead terminals 17a and 17b are preferably arranged on the side surface of the other end 31b of the detection device main body 31 so as to extend in the longitudinal direction. In FIG. 2B, the width of the other end portion 31b of the detection device main body 31 is narrow, but the width of the other end portion 31b may be narrow or narrow. It does not have to be. Examples of the material of the measurement wirings 16a and 16b include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. The material of the measurement electrode lead terminals 17a and 17b is nickel (Ni), platinum (Pt), chromium (Cr), tungsten (W), molybdenum (Mo), aluminum (Al), gold (Au), silver (Ag) ), Copper (Cu), and the like.

(2-3) Dust collection electrode:
The dust collection electrode is disposed on a second wall that is disposed to face the first wall in which the first measurement electrode and the second measurement electrode are embedded with a space therebetween. As such a second wall, for example, among the walls forming the through hole of the detection device main body in which the through hole is formed, the wall on the opposite side to the wall in which the first measurement electrode and the second measurement electrode are embedded is provided. You can cite walls. This dust collecting electrode is also preferably an electrode covered with a dielectric that constitutes the detection device body. As shown in FIG. 10, by applying a voltage between the dust collection electrode 41 and the first measurement electrode 12a and the second measurement electrode 12b, at least one of the first measurement electrode 12a and the second measurement electrode 12b becomes ground, An electric field is generated toward the first measurement electrode 12a and the second measurement electrode 12b. As will be described later, as the ground for the dust collecting electrode 41, in addition to the first measurement electrode 12a and the second measurement electrode 12b, a ground electrode (ground electrode 42 (see FIG. 8)) is additionally provided. May be.

  The shape of the dust collection electrode is not particularly limited as long as it can generate an electric field between the first wall and the second wall toward the first measurement electrode and the second measurement electrode. Absent. In the particulate matter detection device of the present embodiment, as shown in FIG. 4, the dust collection electrode 41 is embedded in a position facing the groove portion 35 of the first wall 33 inside the second wall 34. It is preferable. In particular, it is preferable that a gap is formed in the dust collection electrode 41 at a location facing the region 22a in which the first measurement electrode 12a is embedded and the region 22b in which the second measurement electrode 12b is embedded. In the particulate matter detection device 100 shown in FIG. 4, the dust collection electrode 41 is embedded only in a position facing the groove portion 35 of the first wall 33 inside the second wall 34. By configuring the dust collecting electrode 41 as described above, an electric field can be generated more intensively from the dust collecting electrode 41 to the groove portion 35 of the first wall 33. That is, since the dust collection electrode 41 is not buried at a position facing the region 22a where the first measurement electrode 12a is buried and the region 22b where the second measurement electrode 12b is buried, the electric field from the dust collection electrode 41 However, it concentrates on the periphery of each edge part of the 1st measurement electrode 12a and the 2nd measurement electrode 12b. For this reason, particulate matter can be actively collected inside the groove portion 35. Of course, in the particulate matter detection device of this embodiment, the dust collection electrode may be a single plate-like electrode.

  As the dust collection electrode 41 as shown in FIG. 4, for example, a plurality of comb dust collection electrode portions arranged in a plane along the extending direction of the groove portion 35 of the first wall 33 and a plurality of comb tooth collections are used. The thing which has a comb bone dust collection electrode part which connects a dust electrode part in the end can be mentioned. As described above, the dust collection electrode 41 is also formed into the above-described comb-like electrode, so that wiring can be very easily performed when a voltage is applied to the dust collection electrode 41 (see, for example, FIG. 5). Moreover, when forming the convex part 36 on the surface of the 2nd wall 34 as mentioned above, the position where the dust collection electrode 41 is embedded and the position where the convex part 36 is formed correspond. It is preferable.

  Examples of the material of the dust collection electrode include platinum (Pt), molybdenum (Mo), tungsten (W), and the like.

  In the case where the dust collection electrode is embedded in the second wall, there is no particular limitation on the distance from the dust collection electrode to the surface of the second wall. The “surface of the second wall” is a surface of the second wall facing the first wall. From the viewpoint of electric field strength, the distance from the dust collecting electrode to the surface of the second wall is preferably 0.1 to 0.5 mm, and more preferably 0.1 to 0.25 mm. . By comprising in this way, the electric field for collecting particulate matter can be favorably generated between the first wall and the second wall.

  As shown in FIG. 5, a dust collection wire 41 b extending in the longitudinal direction of the detection device main body 31 is connected to the dust collection electrode 41. The dust collection wiring 41 b is electrically connected to the dust collection electrode extraction terminal 41 a disposed at the other end 31 b of the detection device main body 31. Examples of the material of the dust collection wiring 41b include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. The material of the collecting electrode extraction terminal 41a 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.

(2-4) Ground electrode:
The particulate matter detection device according to the present embodiment may further include a ground electrode for grounding embedded in the first wall. As described above, in the particulate matter detection device of this embodiment, when a voltage is applied to the dust collection electrode, at least one of the first measurement electrode and the second measurement electrode is used as a ground. You can also. The particulate matter detection device further provided with such a ground electrode can detect particulate matter with higher accuracy and sensitivity.

  In the particulate matter detection device 100 shown in FIGS. 2A to 2D and FIGS. 3 to 9, an example in which a ground electrode 42 for grounding is further provided inside the first wall 33 is shown. The first measurement electrode 12a and the second measurement electrode 12b are embedded in the first wall 33 from the surface side in the thickness direction of the first wall 33 (that is, closer to the through hole 32). . Further, the ground electrode 42 is disposed at a position away from the embedded position of the first measurement electrode 12 a and the second measurement electrode 12 b in the thickness direction from the surface of the first wall 33. The ground electrode 42 serves as a ground for the dust collection electrode 41.

  A ground wiring 42 b extending in the longitudinal direction of the detection device main body 31 is connected to the ground electrode 42. The ground wiring 42b is connected to the ground electrode lead-out terminal 42a at the tip that is not connected to the ground electrode 42.

  Examples of the material for the ground electrode include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. In addition, examples of the material of the ground wiring and the ground electrode extraction terminal include the same materials as those of the dust collection wiring and the dust collection electrode extraction terminal.

  The ground electrode is a ground electrode disposed as necessary, and the size thereof is not particularly limited. However, the ground electrode is preferably of a size that can cover at least the entire width of the through hole in the direction in which the through hole extends.

(2-5) Particulate matter amount calculation means:
The particulate matter detection device according to the present embodiment includes particulate matter amount calculation means for measuring the change in electrical characteristics between the first measurement electrode and the second measurement electrode to obtain the amount of particulate matter. . That is, in the particulate matter detection device of the present embodiment, as described so far, the particulate matter contained in the measurement target gas passing between the first wall and the second wall is subjected to the first electric field. Collect dust on the surface of one wall. The electric field is generated by a dust collecting electrode. Then, in the particulate matter detection device of the present embodiment, the change in the electrical characteristics between the first measurement electrode and the second measurement electrode is measured, and the particulate matter collected from the change in the electrical characteristics is measured. Determine the amount of the substance.

  The particulate matter amount calculation means is not particularly limited as long as the particulate matter amount can be obtained by the method described above. For example, examples of the particulate matter amount calculation means include a characteristic measurement unit and a particulate matter amount calculation unit. In addition, the particulate matter detection device of the present embodiment may further include a particulate matter concentration calculation unit that calculates the concentration of the particulate matter in the measurement target gas from the obtained amount of particulate matter. .

  Hereinafter, the principle of detecting the amount of particulate matter in the particulate matter detection device of the present embodiment will be described. First, the amount of change E1 in the electrical characteristics between the first measurement electrode and the second measurement electrode is in a fixed relationship with the amount of particulate matter collected (in other words, the amount of particulate matter deposited W1). . For this reason, if the characteristic measurement unit knows the change amount E1 of the electrical characteristic, the deposition amount W1 of the particulate matter can be obtained. The particulate matter amount calculation unit calculates the particulate matter deposition amount W1 from the electrical property change amount E1 based on the correlation between the electrical property change amount E1 and the particulate matter deposition amount W1. It has a calculation function. Further, if the flow rate of the measurement target gas (for example, exhaust gas) is constant, the particulate matter deposition amount W1 has a constant relationship with the amount of particulate matter in the measurement target gas, that is, the concentration C1 of the particulate matter. There is also. Therefore, if the particulate matter deposition amount W1 is known, the concentration C1 of the particulate matter in the measurement target gas can be obtained. Further, when the flow rate of the measurement target gas changes, the flow rate of the measurement target gas is measured by a flow meter or the like, and the particulate matter concentration C1 is corrected based on the measured flow rate. The concentration C1 of the particulate matter can be obtained from the deposition amount W1. The particulate matter concentration calculation unit has a calculation function for calculating the particulate matter concentration C1 from the particulate matter deposition amount W1 based on the correlation between the particulate matter deposition amount W1 and the particulate matter concentration C1. It is what you have.

  In the particulate matter detection device of the present embodiment, it is preferable that the particulate matter amount calculation means is incorporated in the control device in the particulate matter detection device. The control device is preferably composed of, for example, a sequencer having an electric signal input / output function, and preferably has a control means for controlling the entire apparatus in addition to the particulate matter amount calculation means. Other controls performed by the control means include, for example, control of the power supply for the dust collecting electrode, control of the power supply for the heating unit, which will be described later, switching of the measurement mode, and transmission / reception of the electrical signal of the flow rate measured by the flow meter. Can be mentioned.

  When the impedance is obtained as an electrical characteristic between the first measurement electrode and the second measurement electrode, an AC power source can be used to measure resistance, capacitance, and inductance, respectively. Moreover, you may measure the change of an impedance by using a constant current source and measuring the change of the voltage between a 1st measurement electrode and a 2nd measurement electrode. In addition, by using a constant voltage source, by measuring the change in the current flowing between the first measurement electrode and the second measurement electrode and the change in the charge accumulated between the first measurement electrode and the second measurement electrode The change in impedance between the first measurement electrode and the second measurement electrode may be measured. The characteristic measurement unit can have an appropriate configuration depending on such electrical characteristics and how to obtain the change.

  In the particulate matter detection device of the present embodiment, as described above, a groove is formed between the first measurement electrode and the second measurement electrode. For this reason, by collecting the particulate matter in the groove, it is possible to perform measurement with higher sensitivity when measuring the change in the electrical characteristics described above. Therefore, as a result, it becomes possible to improve the detection sensitivity of the particulate matter detection device.

  For example, the characteristic measurement unit can be composed of an AC power source that applies a voltage to the first measurement electrode and the second measurement electrode, and a measuring instrument. A preferred measuring instrument is an LCR meter. Specifically, for example, when the electrical characteristic to be measured is capacitance, an LCR meter 4263B (trade name) manufactured by Agilent Technologies, Inc. can be used.

  In addition, the particulate matter amount calculation unit and the particulate matter concentration calculation unit are not particularly limited as long as they have the above-described calculation function. For example, an integrated circuit having the above calculation function can be given.

(2-6) Heating part:
The particulate matter detection device of this embodiment may include a heating unit embedded in at least one of the first wall and the second wall. The particulate matter detection device 100 shown in FIGS. 2A to 2D and FIGS. 3 to 9 includes a heating unit 43 embedded in the detection device main body 31. By heating the detection device main body 31 by the heating unit 43, the particulate matter collected on the wall (that is, the first wall 33) forming the through hole 32 can be heated and oxidized. Thus, the particulate matter detection device can be regenerated by burning off the particulate matter collected on the wall. Moreover, when measuring the mass of a particulate matter, the internal space of the through-hole 32 can also be adjusted to desired temperature. By such temperature adjustment, a change in electrical characteristics between the first measurement electrode and the second measurement electrode can be stably measured.

  The heating unit 43 can be formed using, for example, a conductive paste for forming the heating unit. The heating unit 43 may be made of a linear metal material (see, for example, FIG. 9). The heating unit 43 may be a wide film. FIG. 9 shows an example of the heating unit 43 in which a linear metal material is arranged in a wave shape in the longitudinal direction of the detection device main body 31. FIG. 9 shows an example in which two wavy portions extending in the longitudinal direction of the detection device main body 31 are connected by one tip portion 31 c of the detection device main body 31. By adopting such a shape, the inside of the through hole can be heated uniformly, and the particulate matter adhering to the wall forming the through hole can be removed. Examples of the material of the heating unit 43 include platinum (Pt), molybdenum (Mo), tungsten (W), and the like. There is no restriction | limiting in particular about the number of the wiring which forms a heating part.

  The heating unit 43 may be embedded in the detection device main body 31 along the wall surface of the through hole. In addition, as shown in FIG. 9, the heating unit 43 is not provided only at the position where the through hole 32 is formed, but for example, the heating unit is extended to the other end side of the detection device main body. May be provided. 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 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. Moreover, in the particulate matter detection device 100 shown in FIGS. 2A to 2D and FIGS. 3 to 9, the heating unit 43 includes the first wall 33 in which the first measurement electrode 12 a and the second measurement electrode 12 b are embedded. An example in the case of being arranged inside is shown. The heating unit may be disposed at two or more positions. For example, the heating unit 43 may also be disposed inside the second wall 34 where the dust collection electrode 41 is disposed.

  The heating unit 43 is connected to the heating wiring 43b. And the heating wiring 43b is connected to the heating part extraction terminal 43a (for example, refer FIG. 2C). The heating portion extraction terminal 43a is also preferably disposed at the other end 31b of the detection device main body 31, as in the case of the measurement electrode extraction terminals 17a and 17b. Thereby, the influence of the heat when the one end part 31a side of the detection apparatus main body 31 is heated can be avoided. The two heating unit extraction terminals 43a are arranged on the other side surface side of the detection device main body 31 so that two are arranged side by side. However, the arrangement of the heating unit extraction terminals 43a is limited to such an arrangement. is not.

(2-7) Power source for dust collecting electrode:
The particulate matter detection device of this embodiment may further include a dust collection electrode power source for applying a voltage to the dust collection electrode. By applying a voltage to the dust collecting electrode from the power source for the dust collecting electrode, an electric field is generated between the first wall and the second wall from the dust collecting electrode toward the first measuring electrode and the second measuring electrode. be able to.

  The power supply for the dust collecting electrode supplies a stable DC voltage or AC voltage that can generate an electric field between the first wall and the second wall. As the power supply for the dust collecting electrode, for example, a power supply using a power circuit by a flyback method or the like can be adopted. This is capable of supplying a DC voltage by accumulating energy in the transformer from the power supply on the input side and releasing the accumulated energy to the output side. In a flyback power supply circuit, the accumulation and release of energy to and from the transformer are controlled by a transistor or the like, and the current on the output side is rectified by a diode.

(3) Manufacturing method of particulate matter detection device:
Next, the method for manufacturing the particulate matter detection device 100 shown in FIGS. 2A to 2D and FIGS. 3 to 9 will be described as an example of the method for manufacturing the particulate matter detection device of the present embodiment. The method for manufacturing the particulate matter detection device is not limited to the following manufacturing method.

(3-1) Preparation of molding raw material:
First, a forming raw material for manufacturing the detection device main body is prepared. As the molding material, it is preferable to use a dielectric material in which the detection device main body is a dielectric. An example of the dielectric material is a ceramic material. As the ceramic raw material, alumina and zirconia can be suitably used. Apart from the ceramic raw material, the forming raw material may further contain other components. A ceramic raw material and other components used as a forming raw material are mixed to prepare a slurry-like forming raw material. As other raw materials, it is preferable to use a binder, a plasticizer, a dispersant, a dispersion medium and the like.

  As the binder, an aqueous binder or a non-aqueous binder can be used. As the aqueous binder, methyl cellulose, polyvinyl alcohol, polyethylene oxide and the like can be suitably used. As the non-aqueous binder, polyvinyl butyral, acrylic resin, 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-form raw material and shape | molding a green sheet. Moreover, it is possible to prevent the occurrence of cracks and the like when the green sheet is dried and fired.

  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. If the amount of plasticizer added is more than 70 parts by mass, the green sheet may become too soft. Therefore, the green sheet is easily deformed in the process of processing the sheet. Moreover, when the addition amount of a plasticizer is less than 30 mass parts, a green sheet may become hard too much. For this reason, handling may be deteriorated, for example, cracking may occur just by bending the green sheet.

  Examples of the dispersant include aqueous and non-aqueous dispersants. In the aqueous system, an anionic surfactant, wax emulsion, pyridine and the like can be used. In non-aqueous systems, fatty acids, phosphate esters, synthetic surfactants and the like can be used.

  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 agitated 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.

(3-2) Molding process:
Next, the slurry-like forming raw material obtained by the above method is formed into a tape shape to produce a plurality of long green sheets in one direction. The forming method is not particularly limited as long as the forming raw material can be formed into a sheet to form a green sheet. For example, a known method such as a doctor blade method, a press molding method, a rolling method, or a calendar roll method can be used. At this time, at least one 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.

  On the surface of each obtained green sheet, each electrode, heating unit, each wiring, each extraction terminal, etc. constituting the particulate matter detection device are appropriately disposed. Examples of each electrode include a first measurement electrode, a second measurement electrode, a dust collection electrode, and a ground electrode. For example, as shown in FIG. 14, the heating unit 43 and the heating wiring 43b are disposed on the green sheet 80a. The ground electrode 42 is disposed on the green sheet 80b. The first measurement electrode 12a, the second measurement electrode 12b, and the measurement wirings 16a and 16b are disposed on the green sheet 80c. FIG. 14 shows an example in which the ground electrode 42 is also arranged between the measurement wirings 16a and 16b. The ground electrode 42 is disposed on the green sheet 80d. The dust collecting electrode 41 and the dust collecting wiring 41b are disposed on the green sheet 80e. The heating unit 43 and the heating wiring 43b are disposed on the green sheet 80f. The green sheet 80d is the above-described green sheet for forming a through hole, and a portion where the through hole is formed is cut off. Further, the green sheet 80g constitutes one side surface of the detection apparatus main body and is laminated on the green sheet 80f.

  FIG. 14 shows an example in which a dielectric layer 85 having a smaller thickness than each green sheet is disposed between the green sheet 80c and the green sheet 80d. The dielectric layer can be formed by applying a paste-like forming raw material. In FIG. 14, the other end portions of the green sheets 80 a to 80 g are omitted, but each extraction terminal and the like are appropriately arranged at the other end portions of the green sheets 80 a to 80 g. Here, FIG. 14 is a schematic diagram illustrating an example of a method for manufacturing the particulate matter detection device.

  The conductor paste for forming (printing) each electrode, wiring, heating section, and extraction terminal can be appropriately prepared according to each material necessary for forming each electrode, wiring, and the like. For example, the conductor paste can be prepared by adding a solvent such as a binder and terpineol to the raw material powder and sufficiently kneading using a triroll mill or the like. Examples of the raw material powder include those containing at least one selected from the group consisting of gold, silver, platinum, nickel, molybdenum, and tungsten. Each conductor paste containing materials necessary for forming each electrode, wiring, etc. is printed on the surface of the green sheet using screen printing or the like, and each electrode, wiring, heating section, and extraction terminal of a predetermined shape are printed. Form.

  Each green sheet 80a-80g shown in FIG. 14 is laminated | stacked sequentially, and a green sheet laminated body is produced. When producing the particulate matter detection device of the present embodiment, a groove is formed on the surface of the dielectric layer 85 at the stage of sequentially laminating the green sheets 80a to 80g. The groove portion is formed between a region where the first measurement electrode is disposed and a region where the second measurement electrode is disposed. As a method of forming the groove, a method of scraping off a part of the surface of the dielectric layer 85 by laser processing can be exemplified. Alternatively, a green sheet or dielectric layer that has been punched at the position where the groove is to be formed may be separately manufactured, and the green sheet or dielectric layer that has been punched may be disposed on the surface of the green sheet 80a. . In addition, the first measurement electrode is disposed by forming a dielectric layer by printing in the region where the first measurement electrode is disposed and the region where the second measurement electrode is disposed. A groove can be formed between the region and the region where the second measurement electrode is disposed.

  Further, similarly to the formation of the groove portion described above, a convex portion may be formed on the surface of the green sheet 80e opposite to the surface on which the dust collection electrode 41 is disposed. As a method for forming the convex portion, a method of separately producing a green sheet corresponding to the shape of the convex portion and arranging the green sheet on the green sheet 80e can be cited. Alternatively, the surface of the green sheet 80e other than the convex portion may be scraped off by laser processing to form a relatively protruding convex portion on the surface of the green sheet 80a.

  In the manufacturing method of the particulate matter detection device as shown in FIG. 14, the green sheet on which the first measurement electrode and the second measurement electrode are arranged is laminated, dried, and fired to produce the detection device main body. In particular, the particulate matter detection device of the present invention can be manufactured.

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

  Further, a green sheet laminate may be produced by a method as shown in FIG. FIG. 15 is a schematic diagram illustrating another example of the method for manufacturing the particulate matter detection device. In FIG. 15, green sheets 81 d and 81 e are green sheets for forming through holes, and portions where the through holes are formed are cut out. Then, the dielectric layer 87 is disposed so as to cover the portion where the through hole of the green sheet 81 e is formed, and the dust collecting electrode 41 is disposed on the dielectric layer 87. The dust collection wiring 41b is disposed on the green sheet 81e. Other manufacturing methods are the same as the manufacturing method in FIG. That is, the heating unit 43 and the heating wiring 43b are disposed on the green sheet 81a. The ground electrode 42 is disposed on the green sheet 81b. The first measurement electrode 12a, the second measurement electrode 12b, and the measurement wirings 16a and 16b are disposed on the green sheet 81c. The ground electrode 42 is disposed on the green sheet 81d. The heating unit 43 and the heating wiring 43b are disposed on the green sheet 81f. A dielectric layer 86 that is thinner than each green sheet is disposed between the green sheet 81c and the green sheet 81d. And each green sheet 81a-81g is laminated | stacked sequentially, and a green sheet laminated body is produced. Also in the method shown in FIG. 15, it is preferable to form a green sheet laminate after forming a groove on the surface of the dielectric layer 86.

  In the manufacturing method shown in FIG. 15, the green sheet 81d may be omitted. That is, in FIG. 15, the ground electrode 42 is disposed on the green sheet 81d, but the ground electrode 42 may be disposed directly on the dielectric layer 86 disposed on the surface of the green sheet 81c. With this configuration, the gap between the through holes can be adjusted.

(3-3) Firing:
Next, the green sheet laminate is dried and fired to obtain a sensor portion of the particulate matter detection device. Specifically, for example, the green sheet laminate is dried at 60 to 150 ° C. and fired at 1200 to 1600 ° C. When a green sheet contains an organic binder, it is preferable to degrease at 400-800 degreeC before baking. The sensor portion is a component in which each component such as the first measurement electrode, the second measurement electrode, and the dust collecting electrode is appropriately arranged in the detection device body. In the particulate matter detection device of the present embodiment, the sensor portion The part that actually detects the substance.

(3-4) Production of particulate matter detection device:
Next, the sensor part of the obtained particulate matter detection device, the power source for the dust collecting electrode, and the particulate matter amount calculation means are electrically connected to produce the particulate matter detection device of this embodiment. The power supply for the dust collecting electrode and the particulate matter amount calculation means may be incorporated in the control device described above.

  The particulate matter detection device of the present invention can be used for detection of particulate matter in a measurement target gas. For example, according to the particulate matter detection device of the present invention, it is possible to immediately detect the occurrence of a DPF defect and recognize an abnormality of the device. This can contribute to prevention of air pollution.

12a: 1st measurement electrode, 12b: 2nd measurement electrode, 13a, 13b: Comb measurement electrode part, 14a, 14b: Comb measurement electrode part, 16a, 16b: Measurement wiring, 17a, 17b: Measurement electrode extraction terminal, 22a: region where the first measurement electrode is embedded, 22b: region where the second measurement electrode is embedded, 31: detection device body, 31a: one end, 31b: the other end, 31c: one Tip portion, 31d: the other tip portion, 32: through hole, 33: first wall, 34: second wall, 35: groove portion, 36: convex portion, 41: dust collecting electrode, 41a: dust collecting electrode taking out Terminal, 41b: dust collection wiring, 42: ground electrode, 42a: ground electrode extraction terminal, 42b: ground wiring, 43: heating section, 43a: heating section extraction terminal, 43b: heating wiring, 50: power supply for dust collection electrode, 51: Particulate matter, 60: Particulate matter amount calculation Means 61: characteristic measurement unit 62: particulate matter amount calculation unit 63: particulate matter concentration calculation unit 80a, 80b, 80c, 80d, 80e, 80f, 80g, 81a, 81b, 81c, 81d, 81e, 81f, 81g: green sheet, 85, 86, 87: dielectric layer, 100, 101, 102, 103: particulate matter detection device, 112a: first measurement electrode, 112b: second measurement electrode, 131: detection device body 141: Dust collecting electrode, 151: Particulate matter, 200: Particulate matter detection device, G: Gas to be measured.

Claims (10)

A first measurement electrode and a second measurement electrode embedded in a state of being spaced apart from each other inside the first wall made of a dielectric,
The first wall and the second wall are disposed on a second wall disposed opposite to the first wall with an interval therebetween, and an electric field is generated toward the first measurement electrode and the second measurement electrode. A dust collecting electrode for collecting particulate matter contained in the measurement target gas passing between the second wall and the surface of the first wall;
A particulate matter amount calculating means for measuring a change in electrical characteristics between the first measurement electrode and the second measurement electrode and obtaining an amount of the particulate matter collected by the electric field; ,
On the surface of the first wall, the first measurement electrode and the second measurement electrode are disposed between a region where the first measurement electrode is embedded and a region where the second measurement electrode is embedded. A particulate matter detection device in which a groove having a depth up to a position where the material is embedded is formed. Each of the first measurement electrode and the second measurement electrode has a plurality of comb measurement electrode units arranged in a plane, and a comb measurement electrode unit that connects the plurality of comb measurement electrode units at one end thereof Each of the plurality of comb measurement electrodes extends in a direction perpendicular to the flow direction of the measurement target gas, and the plurality of comb measurement electrodes of the first measurement electrode, and the second The plurality of comb-tooth measurement electrode portions of the measurement electrode are embedded in the first wall so as to be interdigitated with a gap in the flow direction of the measurement target gas,
Between each region in which the plurality of comb measurement electrode portions of the first measurement electrode are embedded and each region in which the plurality of comb measurement electrode portions of the second measurement electrode are embedded, The particulate matter detection device according to claim 1, wherein each of the groove portions is formed.   The length from the surface of the first wall to the position where the first measurement electrode and the second measurement electrode are embedded in a cross section perpendicular to the flow direction of the measurement target gas is 10 to 70 µm. The particulate matter detection device according to 1 or 2.   The groove portion is formed on the surface of the first wall so that a width of the groove portion is 30 to 80% with respect to an interval between the first measurement electrode and the second measurement electrode. The particulate matter detection device according to any one of? The dust collecting electrode is embedded in the second wall;
The particulate form according to any one of claims 1 to 4, wherein a convex portion is formed at a position facing the position where the groove portion of the first wall is formed on the surface of the second wall. Substance detection device.   The particulate matter detection device according to claim 5, wherein a shape of the convex portion in a cross section perpendicular to the extending direction of the through hole is a square, a rectangle, a trapezoid, a triangle, a semicircle, or a semielliptical shape.   The shape of the convex portion in a cross section perpendicular to the flow direction of the measurement target gas is convex toward an intermediate portion between the first measurement electrode and the second measurement electrode embedded in the first wall. The particulate matter detection device according to claim 5 or 6, wherein the particulate matter detection device has such a shape. The dust collection electrode is embedded in the second wall at a position facing the groove portion of the first wall,
The gap between the region where the first measurement electrode is embedded and the region where the second measurement electrode is embedded is formed in the dust collection electrode. The particulate matter detection device according to Item.   The dust collection electrode is connected to a plurality of comb dust collection electrode portions arranged in a plane along the extending direction of the groove portion of the first wall and the plurality of comb dust collection electrode portions at one end thereof. The particulate matter detection device according to claim 8, further comprising a comb bone dust collecting electrode portion. One end is provided with a detection device body that is long in one direction in which a through hole is formed,
One wall forming the through hole of the detection device main body is the first wall, and the other wall arranged to face the one wall and the through hole is the second wall. The particulate matter detection device according to any one of claims 1 to 9.

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