JP5864368B2 - Particulate matter detection element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a particulate matter detection element that is used in an exhaust system of an internal combustion engine for automobiles and the like and detects particulate matter mainly composed of soot composed of carbon contained in a gas to be measured, and a manufacturing method thereof.

In automobile diesel engines and the like, environmental pollutants contained in combustion exhaust, particularly particulate matter (hereinafter referred to as PM) mainly composed of soot particles and soluble organic components (SOF) are collected. For this purpose, a diesel particulate filter (hereinafter referred to as DPF) is installed in the exhaust passage. The DPF is made of porous ceramics having excellent heat resistance, and traps PM by allowing combustion exhaust gas to pass through partition walls having a large number of pores.
If the amount of collected PM exceeds the allowable amount, the DPF will become clogged and the pressure loss will increase, or the DPF will be damaged by the heat generated when burning excessively accumulated PM, causing the PM to pass through. The collection ability is restored by periodically performing a regeneration process.

Various PM detection sensors for detecting PM in the gas to be measured have been proposed in order to appropriately detect the DPF regeneration timing and to detect abnormalities such as PM slipping at an early stage.
For example, Patent Document 1 includes a plate-shaped element base material and a pair of measurement electrodes arranged on the element base material. Each measurement electrode includes a plurality of comb-tooth portions arranged in a plane, Comb-like electrode having a comb-bone part connecting a plurality of comb-teeth parts of measurement electrodes at one end thereof, and arranged so that the comb-teeth parts of each measurement electrode are interdigitated with a gap. The comb bone portion of at least one measurement electrode is covered with a comb bone coating portion made of a dielectric material, and a particulate substance is adhered to the pair of measurement electrodes and the periphery thereof, and the gap between the pair of measurement electrodes is A particulate matter detection device that detects particulate matter by measuring changes in electrical characteristics is disclosed.

  Further, Patent Document 2 discloses at least a detection device body that is long in one direction in which two or more through-holes are formed at one end, and at least a dielectric that is embedded in a wall that forms the through-holes and covered with a dielectric. A pair of electrodes, and charged by a charged particulate matter contained in the fluid flowing into the through hole, or by a discharge generated in the through hole by applying a voltage to the pair of electrodes The particulate matter contained in the fluid flowing into the through hole can be electrically adsorbed on the wall surface of the through hole, and the change in the electrical characteristics of the wall forming the through hole is measured. Thus, there is disclosed a particulate matter detection device capable of detecting particulate matter adsorbed on the wall surface of the through hole.

However, as described in Patent Document 1, when so-called comb-like electrodes are formed by a method such as thick film printing or plating, it is extremely difficult to set the gap between the electrodes to 30 μm or less. For this reason, extremely small PM of nanometer level is deposited between the detection electrode layers, and there is a large dead mass until electric characteristics can be detected, and there is a possibility that PM discharge cannot be detected immediately after starting.
In addition, the comb-like detection electrode layer pair printed on the surface of the insulating substrate is further covered with an insulating layer or a dielectric layer, and the capacitance between the detection electrode layers varies depending on the amount of PM deposited on the detection surface. When measured, it was found that the change in capacitance was small and the detection accuracy was low.

  Furthermore, as disclosed in Patent Document 2, PM is introduced into a through-hole partitioned between a pair of plate electrodes covered with a dielectric, and the capacitance between the plate electrodes that changes according to the amount of PM is measured. In this case, the distance between the plate electrodes depends on the thickness of the dielectric layer for partitioning the through holes and the thickness of the dielectric layer covering the plate electrodes. If the distance between the plate electrodes is long, the original plate It has been found that the capacitance formed between the electrodes is small and difficult to detect, and that the change in capacitance when PM is introduced into the through hole is small and the detection accuracy is low.

  Accordingly, in view of such circumstances, the present invention measures the electrical characteristics that change according to the amount of particulate matter contained in the measurement gas deposited on the detection unit, and thereby determines the amount of particulate matter in the measurement gas. It is an object of the present invention to provide a particulate matter detection element for detecting a particulate matter detection element that has a low insensitive mass, little measurement variation, and high detection accuracy, and a method for manufacturing the same.

According to the first aspect of the present invention, at least the detection unit includes a pair of detection electrode layers (10A, 10B) facing each other with a certain gap, and an insulating layer (20) covering the surface of the detection electrode layer. Then, the detection part (2) is fixed to the tip of the substantially flat substrate part (40) and disposed in the gas to be measured, and the particulates present around the detection electrode layers (10A, 10B). A particulate matter detection element that detects the particulate matter contained in the gas to be measured by measuring the capacitance between the detection electrode layers (10A, 10B) that changes according to the amount of the substance or AC impedance. There,
The pair of detection electrode layers (10A, 10B) has a substantially flat plate shape standing in the thickness direction of the substrate portion (40), and
A collection space (30) for collecting particulate matter in the gas to be measured is provided between the pair of detection electrode layers (10A, 10B) opposed via the insulating layer (20) ,
The width (L _CMB ) of the collection space (30) in the longitudinal direction of the element, which is the longitudinal direction of the particulate matter detection element, is the height (T _CUT ) of the detection electrode layer (10A, 10B) in the thickness direction. It is characterized by being formed shorter.

In the invention of claim 2, the detection part (2) includes the detection electrode layer (10A, 10B) formed in a substantially flat plate shape, the insulating layer (200A, 200B) formed in a substantially flat plate shape, and the trapping. It is the laminated structure which accumulated the collection space formation layer (202) which divided the collection space (30).

In the invention of claim 3 , at least in the insulating layer (20), the film thickness (T _DE L ) in the direction (200A, 200B) covering the surfaces of the pair of detection electrode layers (10A, 10B) facing each other. 3 μm or more and 50 μm or less,
The width (L _CMB ) in the element longitudinal direction of the collection space (30) is 3 μm or more and 50 μm or less,
The height (T _CUT ) of the detection electrode layers (10A, 10B) in the thickness direction is 100 μm or more and 2000 μm or less.

In the invention of claim 4, the electrode layer (10A, 10B) is a perovskite-based conductive material selected from any one of MCrO ₃ , MMnO ₃ , and MCoO ₃ (where M is either La or Gd). The insulating layer (20) is an insulating ceramic selected from alumina, zirconia, magnesia, titania, silica, and ceria.

In invention of Claim 5 , it is a manufacturing method of the particulate matter detection element as described in any one of Claims 1 thru | or 4 , Comprising:
At least an electrode layer sheet forming step for forming an electrode layer sheet (10G) in the form of a conductive ceramic material, and a burned layer sheet for forming a burned layer sheet (30G) in the form of a burned material that is burned off by firing. A forming step, an insulating thick sheet forming step for forming an insulating thick sheet (200 TKG) in the form of a sheet of insulating ceramic material, and the insulating thick sheet (200 TKG) made of the insulating ceramic material. An insulating thin sheet forming step for forming a thin insulating thin sheet (200TNG);
The electrode layer sheet (10G) and the insulating thick sheet (200TKK) are overlapped and punched out simultaneously with a mold having a predetermined shape to cut out the electrode layer sheet (10G) into a predetermined shape. An insulating layer embedding step in the electrode layer for forming an embedded electrode layer sheet in which an insulating thick sheet (200 TKG) is embedded;
An embedded burned layer sheet forming step of forming an embedded burned layer sheet in which an insulating film made of the ceramic material and cut into a predetermined shape is embedded in the burned layer sheet (30G);
The embedded electrode layer sheet, the embedded burned layer sheet, and the insulating thin sheet (200TNG) are stacked in a predetermined laminated pattern to cover at least a pair of electrode layers (A layer, B layer). A laminating step for forming a non-fired body (2G) having a laminated structure in which an insulating layer (I layer) and a burned-out layer (V layer) are laminated;
The detection unit laminate green body (2G) obtained by the lamination step is fired, and the detection electrode layer (10A, 10B), the insulating layer (20), and the collection space (30) are integrated in a laminated structure. A laminate firing step for forming the detector laminate (2) of
Through the laminate baking step, resulting detector laminate (2), a predetermined pair of detection lead to achieve a connection with the external (50A, 50B) substantially flat substrate portion provided with (40) And a detector mounting process for mounting and fixing at a position.

According to invention of Claim 1 thru | or 4, the electrostatic capacitance formed between the said detection electrodes (10A, 10B) is large, and when a particulate matter is taken in in the said collection space (30), it is electrostatic. The change in capacity becomes large, there is no dead mass, and the amount of PM in the gas to be measured can be detected with extremely high accuracy.
Further, according to the invention of claim 5, the detection electrodes (10A, 10B) the distance between it is possible to arbitrarily set by the thickness of the burned layer (V layer), the invention of claims 1 to 4 Such an on-particle substance detection element with high detection accuracy can be realized.

1A is a cross-sectional view taken along line AA in FIG. 1B, showing a main part of a particulate matter detection element in a first embodiment of the invention. The C arrow top view which shows the surface seen from C direction in FIG. 1A of the particulate-material detection element in the 1st Embodiment of this invention, and notches one part in steps and shows an internal structure. FIG. 2 is a partially cut-out developed perspective view showing an overall outline of the particulate matter detection element according to the first embodiment of the present invention. The perspective view which shows the manufacturing method of the detection part laminated body used for the particulate matter detection element in 1st Embodiment later on in order of a process, and shows the insulating layer embedding process in an electrode layer which embeds an insulating layer in an electrode layer. FIG. 2B is a cross-sectional view of FIG. 2A. The perspective view which shows the state by which the insulating layer was embedded in the electrode layer. 2C is a cross-sectional view of FIG. 2C during the embedding process. Sectional drawing of the electrode layer of the state with which the insulating layer was embedded. The perspective view which shows the insulating layer embedding process in a burning layer which embeds an insulating layer in a burning layer. FIG. 3B is a cross-sectional view of FIG. The perspective view which shows the state by which the insulating layer was embedded in the burning layer. FIG. 3C is a cross-sectional view of FIG. 3C during the embedding process. Sectional drawing of the burning layer of the state embedded with the insulating layer. The perspective view which shows the outline | summary of a 1st lamination | stacking unit. The perspective view which shows the process following FIG. 4A and shows the outline | summary of a 2nd lamination | stacking unit. The perspective view which shows the process of following FIG. 4A, and shows the process of laminating | stacking alternately the lamination | stacking unit shown to FIG. 2A and FIG. 2B. The perspective view which shows the outline | summary of the 1st division | segmentation process which divides | segments the laminated body obtained through the process of FIG. 4C into an individual detection part laminated body. The perspective view which shows the process following FIG. 5A and shows the outline | summary of the 2nd division | segmentation process which adjusts the edge part of a detection part laminated body. The perspective view which looked at the detection part laminated body obtained through the baking process following FIG. 5B from the back surface side. The perspective view seen from the surface side of FIG. 6A. Sectional drawing along the AA plane in FIG. 6B. The expansion | deployment perspective view which shows the outline | summary of the particulate matter detection element which printed and formed a pair of comb-like electrode on the substrate surface shown as the comparative example 1, and was covered with the dielectric layer. The expansion | deployment perspective view which shows the outline | summary of the particulate matter detection element which partitioned off the collection space by the through-hole between a pair of parallel flat plates which are shown as the comparative example 2 through a dielectric layer. The cross-sectional schematic diagram which shows the electric field distribution formed between the electrodes in this invention. FIG. 6 is a schematic cross-sectional view showing an electric field distribution formed between electrodes in Comparative Example 1. FIG. 5 is a schematic cross-sectional view showing an electric field distribution formed between electrodes in Comparative Example 2. The characteristic view which shows the effect of this invention with a comparative example, and shows the change of the electrostatic capacitance detected when the amount of soot deposited on a detection part is changed. FIG. 9B is an enlarged characteristic diagram of a portion surrounded by a two-dot broken line in FIG. 9A. The characteristic view which shows the influence when changing the width | variety of a collection space with respect to the amount of soot deposits and the electrostatic capacitance detected in embodiment of this invention. Sectional drawing which shows the outline | summary of the particulate matter detection element in the 2nd Embodiment of this invention, and followed AA in FIG. 8B. FIG. 8B is a plan view as viewed in the direction of arrow C, showing the surface viewed from the c direction in FIG. The perspective view which shows the order of a process later about the outline | summary of the manufacturing method of the particulate matter detection element in 2nd Embodiment. FIG. 11B is a perspective view showing a step following FIG. 11A. The perspective view which looked at the detection part laminated body obtained through the baking process following FIG. 11B from the back surface side. The perspective view seen from the surface side of FIG. 12A. Sectional drawing along the AA plane in FIG. 12B. The expansion | deployment perspective view which shows the outline | summary of the particulate matter detection element in the 3rd Embodiment of this invention.

With reference to FIG. 1A, FIG. 1B, and FIG. 1C, the outline | summary of the particulate matter detection element 1 in the 1st Embodiment of this invention is demonstrated.
In the drawings used for the following description, the element longitudinal direction is L direction, the width direction is W direction, and the thickness direction is H direction with respect to the particulate matter detection element 1 formed in a substantially long flat plate shape. It is shown by.
The particulate matter detection element 1 of the present invention includes, as the detection unit 2, a pair of detection electrode layers 10A and 10B that are opposed to each other with a certain gap, and an insulating layer 20 that covers the surfaces of the detection electrode layers 10A and 10B. Then, the detector 2 is fixed to the tip of the substantially flat substrate portion 40 and disposed in the gas to be measured, and the static electricity changes according to the amount of particulate matter present around the detection electrode layers 10A and 10B. The particulate matter contained in the gas to be measured is detected by measuring the electric capacity or the AC impedance.

The particulate matter detection element 1 has a pair of detection electrode layers 10A, 10B standing upright in a direction orthogonal to the substrate portion 40, and is measured between a pair of detection electrode layers 10A, 10B facing each other with an insulating layer 20 therebetween. A collection space 30 for collecting particulate matter in the gas is provided.
In this invention, the detection part 2 mounted in to-be-measured gas is comprised by the detection part laminated body 2 which has the laminated structure formed by the manufacturing method mentioned later.
The detection unit laminate 2 includes a pair of detection electrode layers in which detection electrode layers 10A and 10B formed in a substantially flat plate are alternately arranged, and the surfaces of the detection electrode layers 10A and 10B are covered with an insulating layer 20. In addition, in the insulating layer 20, a soot collection space 30 is defined between the surfaces of the detection electrode layers 10A and 10B facing each other.

The detection electrode layers 10A and 10B are formed of a perovskite-based conductive ceramic selected from one of MCrO ₃ , MMnO ₃ , and MCoO ₃ (where M can be selected from either La or Gd). .
Furthermore, the insulating layer 20 is formed of an insulating ceramic selected from any of alumina, zirconia, magnesia, titania, silica, and ceria.

The detection electrode layers 10A and 10B have an electrode L direction width L _EL (electrode layer film thickness t _EL ) of 100 μm or more and 300 μm or less, and an electrode height H _EL (cutting thickness t _CUT ) of 0.1 mm or more and 2 mm or less. The electrode width W _EL is 2 mm or more and 30 mm or less.
Since the detection electrode layers 10A and 10B of the present invention are formed with a thickness of 100 μm or more, the electrical resistance of the electrode layer itself is low, and the detection accuracy can be increased.
Further, the detection electrode layers 10A and 10B are formed of a conductive ceramic having a high mechanical strength, and play a role of ensuring the strength as a structure.

The insulating layer 20 is interposed between the insulating layers 20A and 20B that cover the detection electrode layers 10A and 10B, and the insulating layer 20A and the insulating layer 20B, and the collection space forming layer 202 that partitions the collection space 30. Insulating layers 20A and 20B are formed of element L-direction insulating layers 200A and 200B that cover the opposing surfaces of detection electrode layers 10A and 10B, and surfaces parallel to the element plane of detection electrode layers 10A and 10B. The element plane direction insulating layers 201A and 201B to be covered and the end face side insulating layers 203A and 203B covering one end face of the detection electrode layers 10A and 10B are formed.
The width L _{CMB in} the element L direction of the collection space 30 defined by the distance between the opposing surfaces of the detection electrode layers 10A and 10B covered with the insulating layer 20 defines the height H _CMB of the collection space 30. The detection electrode layers 10A and 10B covered with the insulating layer 20 are formed shorter than the height (T _CUT ).

Of the insulating layer 20, the thicknesses of the element L direction insulating layers 200A and 200B (element L direction dielectric layer thickness T _DE L) are 3 μm or more and 50 μm or less, and the thicknesses of the element H direction side insulating layers 201A and 201B ( The element H direction dielectric layer thickness T _DE H) is formed to be 10 μm or more and 100 μm or less, and the thickness of the collection layer formation layer 202 (collection layer formation layer thickness t _CMB ) is formed to be 3 μm or more and 50 μm or less. The thickness of the end face side insulating layers 203A and 203B is 10 μm or more and 100 μm or less.

The substrate portion 40 is constituted by insulating layers 400 and 401 in which an insulating ceramic selected from any of alumina, zirconia, magnesia, titania, silica, and ceria is formed in a substantially flat plate shape.
The detection unit laminate 2 is fixed to the surface of the substrate unit 40, and a pair of detection lead units 50A and 50B and a detection lead unit 50A and 50B, which are printed to be electrically connected to the detection electrode layers 10A and 10B. A pair of detection terminals 51 </ b> A and 51 </ b> B that are provided at one end of the terminal and are connected to the outside are formed.
A heating element 41 that generates heat when energized is embedded inside the substrate 40, and a pair of heating element leads 42A and 42B are formed to connect the heating element 41 to the outside, and a pair of through-hole electrodes 44A. , 44B are connected to a pair of terminal portions 43A, 43B formed on the back side of the substrate portion 41.
For the lead portions 42A and 42B, the terminal portions 43A and 43B, and the through-hole electrodes 44A and 44B, a known conductive material such as Pt, Au, Ag, Pd, and Rh is used.
For the heating element 41, a known resistance heating material such as Pt, Au, W, Rh, or Mo is used.

One end of the detection electrode layers 10A and 10B exposed on the back side of the detection unit laminate 2 is connected to the detection lead units 50A and 50B as one end of the connection end portions 101A and 101B, thereby forming a pair of comb-like electrodes. ing.
When an alternating current is passed between the connection terminals 51A and 51B, an electric field is formed between the opposing planes of the detection electrode layers 10A and 10B, and when PM in the gas to be measured is drawn into the soot collection space 30, the detection electrode The capacitance C between the layers 10A and 10B changes. From the change in capacitance detected at this time, the amount of PM existing in the collection space can be calculated.

Here, with reference to FIG. 2A-FIG. 6C, the manufacturing method of the particulate matter detection element 1 in this embodiment is demonstrated later on in order of a process.
First, an outline will be described. In the method for manufacturing the particulate matter detection element 1 of the present invention, at least the electrode layer sheet forming step for forming the conductive ceramic material such as MCrO3 described above into a sheet shape, and the burned-out material that is burned down by firing such as carbon sheet It is obtained by these steps, a burnt-out layer sheet forming step to be formed into a shape, an insulating layer sheet forming step in which an insulating ceramic material such as zirconia is formed into a sheet shape or a film shape, or an insulating layer film forming step. The electrode layer sheet (10G), the burnt-out layer sheet (30G), and the insulating layer sheet / insulating layer film (200TNG) are laminated in a predetermined lamination pattern, and the electrode layers (A layer, B layer), insulating layer (I layer) The stacking step of forming the detection part laminate unfired body 2G in which the burned-out layer (V layer) is laminated, and the obtained detection part laminate unfired body 2G are fired to form the electrode layers 10A, 10 The laminate firing process for forming the detection part laminate 2 in which the insulating layer 20 and the collection space 30 have an integrated laminate structure, and the detection part laminate 2 obtained through the firing process, And a detecting portion mounting step of mounting and fixing at a predetermined position of a substantially flat substrate portion 40 provided with a pair of detecting lead portions 50A and 50B. Hereinafter, a specific manufacturing method will be described.

First, for example, a conductive ceramic material such as lanthanum chromite (La _0.7 Ca _0.3 CrO _2.85 , hereinafter abbreviated as LCC) is used as a main raw material, and 8% yttria-stabilized zirconia (hereinafter abbreviated as 8YSZ). )) Is used as an auxiliary agent, and a dispersion medium such as ethanol, isopentyl acetate and 2-butanol, a dispersant such as sorbitan trioleate, a binder such as polyvinyl butyral, and a plasticizer such as butylbenzyl terephthalate are pulverized with a planetary ball mill or the like. Mixing is performed to prepare a slurry for the conductive layer, which is then formed into a sheet shape by a known doctor blade method or the like to obtain a conductive sheet 10G.
At this time, the sheet thickness t _EL of the conductive sheet 10G is adjusted to be 100 μm or more and 300 μm or less after firing.
In addition, G attached | subjected to a code | symbol means a green sheet, shows the state before baking, and is the same also in the following structures.

In addition, an insulating ceramic such as 8YSZ is used as a main raw material, and LCC is added as an auxiliary agent for adjusting shrinkage and improving adhesion during firing, and a dispersion medium such as ethanol, isopentyl acetate and 2-butanol, and sorbitan trio. A dispersing agent such as a rate, a binder such as polyvinyl butyral, and a plasticizer such as butylbenzyl terephthalate are pulverized and mixed with a planetary ball mill or the like to produce a slurry for an insulating layer, which is formed into a sheet by a known doctor blade method or the like. Thus, the insulating thick sheet 200TKG and the insulating thin sheet 200TNG are obtained.
The insulating thick sheet 200TKG is formed to the same film thickness as the conductive sheet 10G, and the insulating thin sheet 200TNG is formed to a film thickness of 3 μm or more and 50 μm or less. The insulating thin sheet 200TNG may be formed by thick film printing by creating a printing paste using the same kind of insulating ceramic material or the like without depending on the doctor blade method.

Furthermore, a burned-out material that burns down by firing such as carbon, a dispersion medium such as ethanol, isopentyl acetate, 2-butanol, a dispersant such as sorbitan trioleate, a binder such as polyvinyl butyral, a plasticizer such as butylbenzyl terephthalate, By grinding and mixing with a planetary ball mill or the like, a burnt layer slurry is prepared and formed into a sheet by a known doctor blade method or the like to obtain a burned layer sheet 30G.
The burned-out layer sheet 30G is prepared with a film thickness of 3 μm or more and 50 μm or less. Further, when the film thickness of the burnt layer sheet 30G is set to 30 μm or less, a printing paste may be created using the same kind of burnt material and the like may be printed.

In the insulating layer embedding process in the electrode layer, the insulating thick sheet 200TKG obtained through the above-described process and the conductive sheet 10G are overlapped as shown in FIGS. 2A and 2B, and a punched pattern having a predetermined shape is applied. As shown in FIGS. 2C and 2D, using the molds M1 and M2, the insulating thick sheet 200TKG is embedded in the conductive sheet 10G while being cut into a predetermined shape (201AG and 203AG), as shown in FIGS. 2C and 2E. A layer in which a pattern to be the detection electrode layer 10A is formed can be obtained.
In addition, in this embodiment, the pattern from which the four detection part laminated bodies 2 are finally obtained is illustrated.

  Next, as shown in FIGS. 3A and 3B, the insulating thin sheet 200TNG and the burnt-out layer sheet 30G are overlaid and shown in FIGS. 3C and 3D using molds M3 and M4 that have been subjected to a predetermined punching pattern. In this manner, the insulating thin sheet 200TNG is embedded in the burnt-out layer sheet 30G while being cut into a predetermined shape (202G), and a pattern serving as the collection layer forming layer 202 as shown in FIGS. 3C and 3E is formed. Can be obtained.

Next, as shown in FIG. 4A, the I layer obtained by punching the insulating thin sheet 200TNG into a predetermined shape, the A layer obtained through the above steps, the I layer, and the V layer obtained through the above steps. By superimposing the layers, an insulating layer covers the detection electrode layer 10A, and a first stacked unit U1 in which a burned-out layer 30G that becomes the collection space 30 after firing is disposed can be formed.
Similarly, as shown in FIG. 4B, the second laminated unit U2 in which the insulating layer covers the detection electrode layer 10B and the burnt layer 30G that becomes the collection space 30 after firing is disposed may be formed. it can. In addition, the A layer and the B layer, and the first stacked unit U1 and the second stacked unit U2 are in a relationship rotated 180 degrees in the planar direction.

The first laminated unit U1 and the second laminated unit U2 thus obtained are alternately stacked as shown in FIG. 4C, and an I layer made of an insulating thick sheet 200TKG is stacked on the uppermost end, and thermocompression bonding is performed. By doing so, the laminated body module STM is formed.
As shown in FIG. 5A and FIG. 5B, the obtained laminated body module STM1 is cut using a dicing saw 6 to cut and remove the end portions DM1 and DM2, and cut into individual detecting portion laminated body unfired bodies 2G.
In the present embodiment, an example of cutting after lamination and drying is shown, but cutting into pieces may be performed after firing.

By subjecting the obtained detection unit laminate unfired body 2G to heat treatment at a predetermined temperature, the detection unit laminate 2 can be obtained as shown in FIGS. 6A, 6B, and 6C.
As a specific heat treatment method, for example, after degreasing at 600 ° C., baking is performed at 1500 ° C.

In the detection unit laminate 2, the detection electrode layers 10A and 10B are alternately arranged and alternately divided toward the left and right sides of the detection unit laminate 2, and one end of the detection electrode layers 10A and 10B is connected to the connection end portions 101A and 101B. Thus, the other ends of the detection electrode layers 10A and 10B are covered with electrode end insulating layers 203A and 203B as insulating end portions 102A and 102B.
The detection unit laminate 2 that is a main part of the present invention uses the above-described laminated structure, and the width in the element L direction of each layer is determined by the film thickness in the lamination direction of each layer. In addition, the number of teeth of the comb-like electrode can be arbitrarily changed by changing the number of layers, and the degree of freedom is extremely high.

The substrate part 40 has a known resistance heating material such as Pt and a conductive material inside the insulating sheets 400 and 401 formed in a sheet shape by a known manufacturing method such as a doctor blade method using an insulating ceramic such as alumina. The heating element 41 and the pair of heating lead portions 42A and 42B are formed by thick film printing or the like and integrated.
On the back side of the substrate part 40, energization terminal parts 43A and 43B are formed which are connected to the heating element lead parts 42A and 42B via the through-hole electrodes 44A and 44B.
A pair of detection lead portions 50A and 50B and detection terminal portions 51A and 51B for connection to the outside are formed on the surface of the substrate portion 40 by a known manufacturing method such as thick film printing.
The connection end portions 101A and 101B of the detection electrode layers 10A and 10B and the detection lead portions 50A and 50B are connected to each other by a method such as soldering, brazing, or integral firing to achieve electrical conduction, and the substrate portion. By joining 40 and the detection part laminated body 2, the particulate matter detection element 1 of the present invention is completed.
In order to firmly bond the detection unit laminate 2 and the substrate unit 40, an insulating material having an intermediate composition between the insulating material constituting the detection unit laminate 2 and the insulating material constituting the substrate unit 40 is used. The formed sheet may be attached so as to straddle both side surfaces of the output laminate 2 and both side surfaces of the substrate unit 40, and the detection unit laminate 2 and the substrate unit 40 may be fired integrally.

Detection electrode layer 10A, the height _{H EL} and 10B, by changing the cut thickness _{T CUT} when cutting out the detecting unit laminate green body 2G a laminate module STM, for example, 100 [mu] m or more, prepared by the following range 2000μm It is possible to set it to 100 μm or more and 500 μm or less.
Further, the thickness T _DE L of the electrode L direction insulating layers 200A and 200B covering the opposing surfaces of the detection electrode layers 10A and 10B is in a range of 3 μm or more and 50 μm or less by changing the sheet thickness of the insulating thin sheet 200TNG. Can be adjusted, and preferably 5 μm or more and 20 μm or less.
Furthermore, the width L _{GP in} the element L direction of the collection space 30 is determined by the sheet thickness T _BNT of the burned-out layer 30G (equal to the sheet thickness of the collection space forming layer 202G), and is adjusted in the range of 3 μm or more and 50 μm or less. Preferably, the thickness is 5 μm or more and 20 μm or less.
Detection electrode layer 10A, the element L direction width _{L EL} and 10B is determined by the sheet thickness _{T EL} of the conductive thick sheet 200TKG, 100 [mu] m or more, is adjustable in the range 300 [mu] m, preferably, 100 [mu] m or more, 200 [mu] m The following is good.

The thickness T _DE H of the element H-direction insulating layers 201A and 201B covering the surfaces of the detection electrode layers 10A and 10B on the gas to be measured is determined when the insulating layer implantation electrode layer sheets (A layer and B layer) are formed. It can be arbitrarily adjusted according to the pattern formed by M1 and M2 and the cutting position when cutting out the individual piece from the laminate module STM.
In the present invention, the capacitance formed in the collection space 30 by the detection electrode layers 10A and 10B facing each other is detected and taken into the collection space 30 via the element L-direction insulating layers 200A and 200B. Since the amount of PM in the gas to be measured is calculated based on the change in capacitance detected according to the amount of PM measured, depending on the thickness T _DE H of the element H direction insulating layers 201A and 201B The influence on the detection result is small, and it is only necessary to ensure insulation between the detection electrode layer 10A and the detection electrode layer 10B, and the thicknesses T _DE H of the element H direction insulating layers 201A and 201B can be changed as appropriate.

Here, the test performed in order to confirm the effect of this invention is demonstrated. A particulate matter detection element 1z shown as Comparative Example 1 in FIG. 7A and a particulate matter detection element 1y as Comparative Example 2 are prepared in FIG. 7B, and the comparison with the particulate matter detection element 1 in the embodiment of the present invention is made. went.
In Comparative Example 1 and Comparative Example 2, the same components as those of the present invention are denoted by the same reference numerals, and the components having different points are denoted by z and y as branch numbers, respectively. . Both Comparative Example 1 and Comparative Example 2 are similar to the present invention in that the heating element 41 is built in the substrate part 40.
As shown in FIG. 7A, the particulate matter detection element 1z shown as the comparative example 1 has a pair of comb-like electrodes 10zA and 10zB, detection lead portions 51zA and 52zA on the surface of the insulating substrate portion 40 in which the heating element 41 is embedded. detection terminal 51ZB, the 52zB thick film printing form, which thickness _{t DE} is are covered with 10μm dielectric layer 200z.
Particulate matter detection device 1y as a comparative example 2, as shown in FIG. 7B, penetrating the side surface direction of the insulating substrate defines a collecting space 30z, respectively, the thickness _{t DE} is 250μm dielectric layer 200yA A pair of parallel plate electrodes 10yA and 10yB facing the collection space 30y through 200yB are formed, and the surfaces thereof are covered with insulating layers 201yA and 201yB.
In Comparative Example 1, each of the detection electrode layers 10Az and 10Bz constituting the pair of comb-like electrodes has a film thickness t _EL of about 10 μm and an electrode area S of 0.25 cm ² (for example, 2.5 mm width × 10 mm length). ) And the interelectrode distance L _GP is set to 50 μm.
In Comparative Example 2, the electrode area S of the pair of parallel plate electrodes 10Ay and 10By is set to 0.5 cm2, and the distance between the parallel plates is 1000 μm.

8A, FIG. 8B, and FIG. 8C schematically show the difference in the electric field formed when alternating current is applied between the detection electrode layers in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention, respectively. It is.
In the particulate matter detection element 1 of the present invention, the pair of detection electrode layers 10 </ b> A and 10 </ b> B has a substantially flat plate shape that stands in a direction orthogonal to the substrate portion 40 and is opposed to the pair of detection electrodes via the insulating layer 20. Since the collection space 30 for collecting the particulate matter in the gas to be measured is defined between the electrode layers 10A and 10B, as shown in FIG. 8A, static electricity formed between the detection electrode layers 10A and 10B. When a voltage is applied between the detection electrode layers 10A and 10B to measure the capacitance, a strong electric field E is formed between the opposing surfaces of the detection electrode layers 10A and 10B, and the particulate matter PM is formed in the collection space 30. Is drawn.
In the particulate matter detection element 1 of the present invention, the capacitance formed between the detection electrode layers 10A and 10B is proportional to the area S of the opposing surfaces of the detection electrode layers 10A and 10B, and the detection electrode layer 10A. Since the width L _CMB of the collection space 30 is shorter than the height H _CMB of the collection space 30 because it is inversely proportional to the distance between 10B, the capacitance becomes much larger than when the detection electrode is printed and formed. The change in capacitance when PM is taken into the collection space 30 also increases.
The capacitance measured between the detection electrodes 10A and 10B is the insulating layer 200A covering the surface of the collection space 30 facing the capacitance of the air layer (gas to be measured) and the detection electrode layers 10A and 10B. It is determined by the combined capacitance with the capacitance of the insulating layer determined by the relative dielectric constant of 200B, and changes according to the amount of PM present in the collection space 30.

  On the other hand, in Comparative Example 1, the electric field Ez formed between the detection electrode layers 10Az and 10Bz arches the insulating layer 200z between the two-dimensional detection electrode layers 10Az and 10Bz as shown in FIG. 8B. Therefore, a high electric field density as in the present invention cannot be obtained. Furthermore, in Comparative Example 1, since the insulating layer 200z is filled between the detection electrodes 10Az and 10Bz, there is no space for collecting PM, and deposition is performed on the element surface. Depending on the case, PM deposited on the element surface may flow away, and the detection result may not be stable.

  In Comparative Example 2, as in the present invention, the electric field Ey acts between the detection electrode layers 10Ay and 10By facing each other, but the distance between the electrodes (for example, 250 μm + 500 μm + 250 μm = 1 mm) is long, and the detection electrode layers 10Ay, 10By. The capacitance detected in the meantime is much smaller than that of the particulate matter detection element 1 of the present invention.

In order to confirm the effect of the present invention, the particulate matter detection element 1 of the present invention (Example 1) and the particulate matter detection in which the surfaces of a pair of conventional comb-like electrodes formed by printing are covered with a dielectric. Combustion exhaust is generated using the element 1z (Comparative Example 1) and the particulate matter detection element 1y (Comparative Example 2) in which a through-hole is provided in the lateral direction of the base between a pair of parallel plate electrodes covered with a dielectric. As the simulated gas to be measured, the atmosphere is flowed at a gas flow rate of 1 m / s, PM is imitated, carbon is supplied at a speed of 8 μg / s, the temperature around the particulate matter detection element is adjusted to 200 ° C., The measurement frequency was set to 10 kHz, and the change in capacitance between the detection electrodes was measured. The results are shown in FIGS. 9A and 9B.
In the particulate matter detection element 1 of the present invention, the width LCMB of the collection space 30 formed between the detection electrode layers 10B and 10B, that is, the plate thickness t _BNT of the collection space forming layer (202) is from 5 μm. The effect of changing to 20 μm was measured, and the result is shown in FIG. 9C.
As shown in FIG. 9A and FIG. 9B, in Example 1 using the particulate matter detection element 1 of the present invention, compared to Comparative Example 1 and Comparative Example 2, electrostatic charge detected with respect to a change in PM amount Q is detected. It can be seen that the change in the capacitance C is large and the PM detection capability is much higher.
Further, as shown in FIG. 9B, in Example 1, a very small amount of PM can be detected, and there is no dead period as in the prior art.
Furthermore, as shown in FIG. 9C, the shorter the width L _CMB of the collection space 30, that is, the shorter the distance between the detection electrode layers 10A and 10B, the greater the change in capacitance, and the measurement sensitivity can be improved. found.
In the present invention, as described above, the width L _CMB of the discharge space 30 can be arbitrarily adjusted from 3 μm to 50 μm by adjusting the thickness of the collection space forming layer 202, so the degree of freedom as a sensor is extremely high. .

With reference to FIG. 10A and 10B, the particulate matter detection element 1a in the 2nd Embodiment of this invention is demonstrated.
In the above-described embodiment, the detection electrode layers 10A and 10B are provided independently in the detection unit stacked body 2, and are connected to the detection lead units 50A and 50B provided on the surface of the substrate 40, thereby forming a pair of combs. In the present embodiment, the detection electrode layers 10A and 10B are connected to the common electrodes 12A and 12B at the connection end portions 101A and 101B in the detection unit laminate 2a. Are connected to the detection lead portions 50A and 50B on the bottom side of the element, respectively, and the outer surfaces of the common electrodes 12A and 12B are connected to the insulating layer 204A. , 205A, 204B, and 205B are different. Also in this embodiment, the same effect as the above embodiment is exhibited.
In addition, in the above embodiment, it is necessary to securely connect all of the connection ends 101A and 101B of the plurality of detection electrode layers 10A and 10B to the detection lead portions 50A and 50B, but in this embodiment, Since the detection electrode layers 10A and 10B and the common electrodes 12A and 12B are connected in advance in the detection unit laminate 2a, the mounting operation on the substrate unit 40 is extremely easy.

With reference to FIG. 11A, FIG. 11B, FIG. 12A, FIG. 12B, and FIG. 12C, the manufacturing method of the particulate matter detection element 1a in 2nd Embodiment is demonstrated.
In the present embodiment, the process similar to the process shown in FIGS. 2A to 4B is performed to form the multilayer module STM, and then the conductive sheet 10G is used as the common electrodes 12A and 12B, and the insulating layers 204AG, As shown in FIGS. 11A and 11B, the electrode layers 10 </ b> A and 10 </ b> B and the common electrodes 12 </ b> A and 12 </ b> B are bonded together from both sides of the multilayer module STM as shown in FIGS. 11A and 11B using the insulating layer sheet 200TNG as 205AG, 204BG, and 205BG. It is possible to form a stacked body module STMa that is connected and covered by the insulating layers 204A, 205A, 204B, and 205B.
A pair of comb-like electrodes were formed in the interior as shown in FIGS. 12A, 12B, and 12C by cutting out and firing the individual detector stacks 2a in the same manner as in the first embodiment. The detector stack 2a can be formed.
The particulate matter detection element 1a according to the second embodiment is completed by mounting the detection unit laminate 2a thus obtained on the substrate unit 40 on which the detection lead units 50A and 50B are formed.

With reference to FIG. 13, a particulate matter detection element 1c according to a third embodiment of the present invention will be described.
In the above-described embodiment, the method of simultaneously forming a plurality of detection unit stacks 2 has been shown, but as a matter of course, one detection unit stack 2c may be formed as shown in the figure, Based on this as a basic configuration, a large number may be formed simultaneously.
The A layer is formed by embedding the detection electrode layer 10Ac and the common electrode layer 121Bc in the insulating thick sheet 200TKG.
The B layer is obtained by rotating the A layer 180 degrees in the plane direction, and is formed by embedding the detection electrode layer 10Bc and the common electrode layer 121Ac in an insulating thick sheet 200TKG.
The C layer is formed by embedding the common electrode layers 120Ac and 120Bc in the insulating thin sheet 200THG. The C layer may be formed by thick film printing.
The V layer is formed by embedding the burnt layer sheet 30G and the common electrode layers 122Ac and 122Bc into the insulating layer 200TNG. The V layer may also be formed by thick film printing.
As shown in this figure, the A layer, C layer, V layer, C layer, B layer, C layer, V layer,... Are repeatedly laminated, and the E layer made of the insulating thick sheet 200THK is formed at the terminal portion. The detection unit laminate 2c is completed by laminating, pressing and firing.
By mounting the obtained detection unit laminate 2c on the substrate unit 40, the particulate matter detection element 1c in the present embodiment is completed.
In the above manufacturing method, when the layers are stacked, a dummy portion may be provided around the layers so that guide pins for positioning can be inserted.
In the manufacturing method described above, thermocompression bonding is described as a basis. However, an adhesive layer including an intermediate material between upper and lower layers may be applied and laminated as necessary.

  Note that the insulating layers 201A and 201B are embedded regardless of the method of previously embedding the insulating layers 201A and 201B that cover the H-direction surfaces of the detection electrode layers 10A and 10B as in the above manufacturing method. Without repeating, the conductor layer sheet 10G, the I layer, and the V layer are repeatedly laminated, and then the insulating layer is printed on one end face and fired to form a portion of the insulating layer where the burnt-out layer is formed. Although it may be burned out together with the burned-out layer, the insulating layer may remain so as to block the opening of the collection space, or the insulating layer covering the electrode layer surface may be peeled off, which is not reliable. It is not valid.

DESCRIPTION OF SYMBOLS 1 Particulate matter detection element 10A, 10B Detection electrode layer 10G Conductive sheet 101A, 101B Connection end part 102A, 102B Electrode layer insulation end part 2 Detection part laminated body 20A, 20B Insulation layer 200TKG Insulation thick sheet 200TNG Insulation thin sheet 200A, 200B Electrode facing side insulating layer 201A, 201B Element plane direction insulating layer 202 Collection space forming layer 203A, 203B Electrode end insulating layer 30 煤 Collection space 30G Burnt layer sheet 40 Substrate part 400, 401 Insulating substrate 41 Heating element 50A, 50B Detection electrode layer lead part 6 Dicing saw A layer, B layer Insulating layer embedded electrode layer I layer Insulating layer C layer Conductive layer embedded insulating layer V layer Burnout layer STM Multilayer module M1, M2, M3, M4 Mold

JP 2012-47596 A JP 2009-276151 A

Claims (5)

At least, the detection unit includes a pair of detection electrode layers (10A, 10B) facing each other with a certain gap, and an insulating layer (20) covering the surface of the detection electrode layer, and the detection unit (2 ) Is fixed to the tip of the substantially flat substrate portion (40) and disposed in the gas to be measured, and changes according to the amount of particulate matter existing around the detection electrode layer (10A, 10B). A particulate matter detection element for measuring a capacitance between the detection electrode layers (10A, 10B) or an alternating current impedance to detect particulate matter contained in the gas to be measured,
The pair of detection electrode layers (10A, 10B) has a substantially flat plate shape standing in the thickness direction of the substrate portion (40), and
A collection space (30) for collecting particulate matter in the gas to be measured is provided between the pair of detection electrode layers (10A, 10B) opposed via the insulating layer (20) ,
The width (L _CMB ) of the collection space (30) in the longitudinal direction of the element, which is the longitudinal direction of the particulate matter detection element, is the height (T _CUT ) of the detection electrode layer (10A, 10B) in the thickness direction. A particulate matter detection element characterized by being formed shorter than the above. The detection unit (2)
The detection electrode layer (10A, 10B) formed in a substantially flat plate shape;
The insulating layer (200A, 200B) formed in a substantially flat plate shape;
2. The particulate matter detection element according to claim 1, wherein the particulate matter detection element has a stacked structure in which collection space forming layers (202) dividing the collection space (30) are stacked. At least in the insulating layer (20), the thickness (T _DE L ) in the direction (200A, 200B) covering the surfaces of the pair of detection electrode layers (10A, 10B) facing each other is 3 μm or more and 50 μm or less. With
The width (L _CMB ) in the element longitudinal direction of the collection space (30) is 3 μm or more and 50 μm or less,
The particulate matter detection element according to claim 1 or 2 , wherein a height (T _CUT ) of the detection electrode layer (10A, 10B) in the thickness direction is 100 µm or more and 2000 µm or less. The electrode layer (10A, 10B) is a perovskite-based conductive ceramic selected from any one of MCrO ₃ , MMnO ₃ , and MCoO ₃ (where M is either La or Gd),
The particulate matter detection element according to any one of claims 1 to 3, wherein the insulating layer (20) is an insulating ceramic selected from alumina, zirconia, magnesia, titania, silica, and ceria. . It is a manufacturing method of the particulate matter detection element according to any one of claims 1 to 4 ,
At least an electrode layer sheet forming step for forming an electrode layer sheet (10G) in the form of a conductive ceramic material, and a burned layer sheet for forming a burned layer sheet (30G) in the form of a burned material that is burned off by firing. A forming step, an insulating thick sheet forming step for forming an insulating thick sheet (200 TKG) in the form of a sheet of insulating ceramic material, and the insulating thick sheet (200 TKG) made of the insulating ceramic material. An insulating thin sheet forming step for forming a thin insulating thin sheet (200TNG);
The electrode layer sheet (10G) and the insulating thick sheet (200TKK) are overlapped and punched out simultaneously with a mold having a predetermined shape to cut out the electrode layer sheet (10G) into a predetermined shape. An insulating layer embedding step in the electrode layer for forming an embedded electrode layer sheet in which an insulating thick sheet (200 TKG) is embedded;
An embedded burned layer sheet forming step of forming an embedded burned layer sheet in which an insulating film made of the ceramic material and cut into a predetermined shape is embedded in the burned layer sheet (30G);
The embedded electrode layer sheet, the embedded burned layer sheet, and the insulating thin sheet (200TNG) are stacked in a predetermined laminated pattern to cover at least a pair of electrode layers (A layer, B layer). A laminating step for forming a non-fired body (2G) having a laminated structure in which an insulating layer (I layer) and a burned-out layer (V layer) are laminated;
The detection unit laminate green body (2G) obtained by the lamination step is fired, and the detection electrode layer (10A, 10B), the insulating layer (20), and the collection space (30) are integrated in a laminated structure. A laminate firing step for forming the detector laminate (2) of
Through the laminate baking step, resulting detector laminate (2), a predetermined pair of detection lead to achieve a connection with the external (50A, 50B) substantially flat substrate portion provided with (40) A method for producing a particulate matter detection element, comprising: a detection unit mounting step for mounting and fixing at a position.

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