JP2011102754A

JP2011102754A - Deposition amount detection device and detection system

Info

Publication number: JP2011102754A
Application number: JP2009257858A
Authority: JP
Inventors: Kiyoshige Miyawaki; 清茂宮脇; Shingo Sato; 慎吾佐藤; Hiroshi Makino; 浩牧野
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2009-11-11
Filing date: 2009-11-11
Publication date: 2011-05-26

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deposition amount detection device and a detection system capable of improving detection sensitivity. <P>SOLUTION: This deposition amount detection device includes: a laminate 31 provided in an exhaust passage U through which exhaust gas from an internal combustion engine is moved, and having a main surface 31a; a pair of electrodes 32a, 32b buried in the laminate 31; and a deposition amount calculation part 4 for calculating a deposition amount of particulate matters included in the exhaust gas, which are deposited on the main surface 31a of the laminate 31, based on a capacitance change between a pair of electrodes 32a, 32b. The laminate 31 has at least a first layer 311, and a second layer 312 laminated on the first layer 311, and the pair of electrodes 32a, 32b is provided on the first layer 311 of the laminate 31 mutually oppositely in a plan view, and is covered with the second layer 312 of the laminate 31, and a dielectric constant of the second layer 312 of the laminate 31 is lower than a dielectric constant of the first layer 311 of the laminate 31. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、排気ガス中に含まれる粒子状物質の堆積量を検出する堆積量検出装置、および検出システムに関する。 The present invention relates to a deposition amount detection device and a detection system for detecting a deposition amount of particulate matter contained in exhaust gas.

排気ガス中に含まれる粒子状物質（ＰＭ：Particulate Matter）の堆積量を検出する堆積量検出装置としては、例えば、静電容量の変化を利用して堆積量を検出する、いわゆる静電容量型の堆積量検出装置が知られている（例えば、特許文献１および２参照）。 As a deposition amount detection device that detects the deposition amount of particulate matter (PM) contained in exhaust gas, for example, a so-called capacitance type that detects a deposition amount by using a change in capacitance. (See, for example, Patent Documents 1 and 2).

特開２００１−３３４１２号公報JP 2001-33412 A 特表２０００−５１７４２６号公報Special Table 2000-517426

しかしながら、上記従来の堆積量検出装置では、粒子状物質の堆積量を、単に、一対の電極間の静電容量の変化に基づいて算出しているので、粒子状物質が堆積されていない場合と粒子状物質が堆積されている場合とにおける静電容量の変化率が小さく、検出感度が悪いという問題があった。 However, in the above conventional accumulation amount detection device, the accumulation amount of the particulate matter is simply calculated based on the change in the capacitance between the pair of electrodes. There has been a problem that the rate of change in capacitance between the case where particulate matter is deposited is small and the detection sensitivity is poor.

本発明は、上記の問題点に鑑みてなされたものであり、その目的は、検出感度を向上することができる堆積量検出装置、および検出システムに関する。 The present invention has been made in view of the above problems, and an object thereof is related to a deposition amount detection device and a detection system that can improve detection sensitivity.

上記目的を達成するために本発明における堆積量検出装置は、内燃機関の排気ガスが移動する排気通路に設けられており、かつ主面を有する積層体と、前記積層体に埋設された一対の電極と、前記排気ガス中に含まれる粒子状物質が前記積層体の主面に堆積された堆積量を、前記一対の電極間の静電容量の変化に基づいて算出する堆積量算出部と、を備え、前記積層体は、第１層と、前記第１層に積層された第２層とを少なくとも有し、前記一対の電極は、平面視において互いに対向するように前記積層体の第１層上に設けられており、かつ前記積層体の第２層で覆われており、前記積層体の第２層の誘電率は、前記積層体の第１層の誘電率よりも低い。 In order to achieve the above object, a deposition amount detection apparatus according to the present invention is provided in an exhaust passage through which exhaust gas of an internal combustion engine moves, and has a laminate having a main surface and a pair of embedded in the laminate. An electrode, and a deposition amount calculation unit that calculates a deposition amount in which particulate matter contained in the exhaust gas is deposited on the main surface of the laminate based on a change in capacitance between the pair of electrodes; The stacked body has at least a first layer and a second layer stacked on the first layer, and the pair of electrodes are arranged so that the pair of electrodes face each other in plan view. The dielectric constant of the second layer of the multilayer body is lower than the dielectric constant of the first layer of the multilayer body, which is provided on the layer and covered with the second layer of the multilayer body.

本発明の堆積量検出装置、および検出システムは、検出感度を向上することができるという効果を奏する。 The accumulation amount detection device and the detection system of the present invention have an effect that detection sensitivity can be improved.

図１は、本実施形態に係る検出システムの概略構成を示すブロック図である。FIG. 1 is a block diagram showing a schematic configuration of a detection system according to the present embodiment. 図２は、本実施形態に係る堆積量検知センサの概略構成を示す斜視図である。FIG. 2 is a perspective view illustrating a schematic configuration of the accumulation amount detection sensor according to the present embodiment. 図３は、積層体の第２層を省略し、図２の矢印Ｎの方向から見た場合の堆積量検知センサを示す平面図である。FIG. 3 is a plan view showing a deposition amount detection sensor when the second layer of the laminate is omitted and viewed from the direction of arrow N in FIG. 図４は、図３中に示した切断線Ｉ−Ｉに沿って切断した断面図である。4 is a cross-sectional view taken along a cutting line II shown in FIG. 図５は、シミュレーションで測定した結果を示す図である。FIG. 5 is a diagram illustrating a result of measurement by simulation. 図６は、変更例３に係る堆積量検知センサの概略構成を示す断面図である。FIG. 6 is a cross-sectional view illustrating a schematic configuration of a deposition amount detection sensor according to Modification 3.

以下、本発明の実施形態について、図面を参照しながら説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図１は、本実施形態に係る検出システム１の概略構成を示すブロック図である。図１に示すように、本実施形態に係る検出システム１は、例えば、図示しない車両（自動車等）等の石油系燃料を使用する燃焼装置に設けられるものであって、フィルタ装置２、堆積量検知センサ３、堆積量算出部４、流量センサ５、流量算出部６、ＥＣＵ（Electronic Control Unit）７、および制御部８を備えている。ここで、堆積量検知センサ３および堆積量算出部４が、本発明に係る堆積量検出装置の一実施形態となる。 FIG. 1 is a block diagram showing a schematic configuration of a detection system 1 according to the present embodiment. As shown in FIG. 1, a detection system 1 according to the present embodiment is provided in a combustion apparatus that uses petroleum fuel such as a vehicle (automobile or the like) (not shown). A detection sensor 3, a deposition amount calculation unit 4, a flow rate sensor 5, a flow rate calculation unit 6, an ECU (Electronic Control Unit) 7, and a control unit 8 are provided. Here, the accumulation amount detection sensor 3 and the accumulation amount calculation unit 4 constitute an embodiment of the accumulation amount detection device according to the present invention.

フィルタ装置２は、排気通路Ｕに設けられており、排気通路Ｕを移動する排気ガス中に含まれる粒子状物質を捕集するための装置である。フィルタ装置２は、例えば、ＤＰＦ（Diesel Particulate Filter）から構成される。すなわち、排気ガスは、ディーゼルエンジン、ピストンエンジン、ガスタービンエンジン等の内燃機関が燃焼することによって発生するとともに、図１の矢印で示されているように、内燃機関（上流）から消音器（下流）に向かって排気通路Ｕを移動する。なお、消音器を通過した排気ガスは、外部へ放出される。ここで、排気ガス中に含まれる粒子状物質としては、例えば、単純な固形の炭素の微粒子が房状に連なったもの、ＳＯＦ（Soluble Organic Fraction）と呼ばれる高分子炭化水素、あるいは硫酸塩等が挙げられる。この粒子状物質は、人の気道や肺に沈着するので、人体へ悪影響を及ぼすとともに、大気汚染の要因ともなり得る。そのため、フィルタ装置２において粒子状物質が捕集される。 The filter device 2 is provided in the exhaust passage U and is a device for collecting particulate matter contained in the exhaust gas moving through the exhaust passage U. The filter device 2 is composed of, for example, a DPF (Diesel Particulate Filter). That is, exhaust gas is generated when an internal combustion engine such as a diesel engine, piston engine, gas turbine engine, or the like burns, and, as indicated by an arrow in FIG. 1, a silencer (downstream) from the internal combustion engine (upstream). ) To the exhaust passage U. The exhaust gas that has passed through the silencer is released to the outside. Here, as the particulate matter contained in the exhaust gas, for example, simple solid carbon fine particles linked in tufts, a polymer hydrocarbon called SOF (Soluble Organic Fraction), or sulfates are included. Can be mentioned. Since the particulate matter is deposited in the human respiratory tract and lungs, it can adversely affect the human body and cause air pollution. Therefore, the particulate matter is collected in the filter device 2.

堆積量検知センサ３は、排気ガス中に含まれる粒子状物質の堆積量を検出するためのセンサであって、フィルタ装置２よりも下流側（消音器側）の排気通路Ｕに設けられている。 The accumulation amount detection sensor 3 is a sensor for detecting the accumulation amount of particulate matter contained in the exhaust gas, and is provided in the exhaust passage U on the downstream side (muffler side) from the filter device 2. .

図２は、本実施形態に係る堆積量検知センサ３の概略構成を示す斜視図である。図２に示すように、本実施形態に係る堆積量検知センサ３は、外観視直方体状であって、排気通路Ｕに設けられた台座Ｂの上に設けられている。なお、台座Ｂを設けることなく、直接、堆積量検知センサ３を排気通路Ｕに設けるようにしてもよい。また、本実施形態に係る堆積量検知センサ３は、外観視直方体状であるが、これに限らず、丸棒状、板状等であってもよく、その形状については特に限定されない。 FIG. 2 is a perspective view showing a schematic configuration of the accumulation amount detection sensor 3 according to the present embodiment. As shown in FIG. 2, the accumulation amount detection sensor 3 according to the present embodiment has a rectangular parallelepiped appearance and is provided on a base B provided in the exhaust passage U. The accumulation amount detection sensor 3 may be directly provided in the exhaust passage U without providing the base B. Moreover, although the accumulation amount detection sensor 3 according to the present embodiment has a rectangular parallelepiped appearance, it is not limited thereto, and may be a round bar shape, a plate shape, or the like, and the shape is not particularly limited.

堆積量検知センサ３は、主面３１ａを有する積層体３１を備えている。本実施形態に係る積層体３１は、第１層３１１と、第１層３１１に積層された第２層３１２とを有しているが、これに限らず、３層以上積層されていてもよい。なお、図３は、積層体３１の第２層３１２を省略し、図２の矢印Ｎの方向から見た場合の堆積量検知センサ３を示す平面図である。図４は、図３中に示した切断線Ｉ−Ｉに沿って切断した断面図である。 The accumulation amount detection sensor 3 includes a stacked body 31 having a main surface 31a. The stacked body 31 according to the present embodiment includes the first layer 311 and the second layer 312 stacked on the first layer 311. However, the present invention is not limited thereto, and three or more layers may be stacked. . 3 is a plan view showing the accumulation amount detection sensor 3 when the second layer 312 of the stacked body 31 is omitted and viewed from the direction of the arrow N in FIG. 4 is a cross-sectional view taken along a cutting line II shown in FIG.

ここで、積層体３１の主面３１ａは、排気通路Ｕの長手方向（図２の矢印Ｎの方向）に対して略垂直な面であり、排気ガスの風の影響を直接受ける面となる。このため、積層体３１の主面３１ａ上に、フィルタ装置２で捕集できなかった粒子状物質が堆積されることになる。ここで、積層体３１としては、例えば、酸化アルミニウム質焼結体、窒化アルミニウム質焼結体、ムライト質焼結体、炭化珪素質焼結体、窒化珪素質焼結体、あるいはガラスセラミック焼結体等のセラミック材料が挙げられる。このため、積層体３１は、第１層３１１となるセラミックグリーンシートと、第２層３１２となるセラミックグリーンシートとが同時に焼成されることによって構成される。 Here, the main surface 31a of the laminated body 31 is a surface substantially perpendicular to the longitudinal direction of the exhaust passage U (the direction of the arrow N in FIG. 2), and is a surface that is directly affected by the wind of the exhaust gas. For this reason, the particulate matter that could not be collected by the filter device 2 is deposited on the main surface 31 a of the multilayer body 31. Here, as the laminated body 31, for example, an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or a glass ceramic sintered body is used. A ceramic material such as a body may be mentioned. For this reason, the laminated body 31 is comprised by baking the ceramic green sheet used as the 1st layer 311 and the ceramic green sheet used as the 2nd layer 312 simultaneously.

また、積層体３１には、第１電極３２ａおよび第２電極３２ｂが埋設されている。具体的には、第１電極３２ａおよび第２電極３２ｂは、平面視において互いに対向するように積層体３１の第１層３１１上に設けられており、かつ積層体３１の第２層３１２で覆われている。なお、第１電極３２ａおよび第２電極３２ｂは、一対の電極であって、その形状は、図３に示すように、平面視において櫛歯状である。第１電極３２ａおよび第２電極３２ｂは、所定の隙間を介して互いに噛み合うように積層体３１の第１層３１１上に設けられている。ここで、第１電極３２ａおよび第２電極３２ｂは、例えば、銀、銅、金、白金、パラジウム、タングステン、モリブデン、またはマンガン等の金属材料からなる。 In addition, the first electrode 32 a and the second electrode 32 b are embedded in the stacked body 31. Specifically, the first electrode 32 a and the second electrode 32 b are provided on the first layer 311 of the stacked body 31 so as to face each other in plan view, and are covered with the second layer 312 of the stacked body 31. It has been broken. In addition, the 1st electrode 32a and the 2nd electrode 32b are a pair of electrodes, As shown in FIG. 3, the shape is a comb-tooth shape in planar view. The first electrode 32a and the second electrode 32b are provided on the first layer 311 of the multilayer body 31 so as to mesh with each other with a predetermined gap. Here, the 1st electrode 32a and the 2nd electrode 32b consist of metal materials, such as silver, copper, gold | metal | money, platinum, palladium, tungsten, molybdenum, or manganese, for example.

このように、第１電極３２ａおよび第２電極３２ｂが平面視において櫛歯状であり、かつ所定の隙間を介して互いに噛み合うように設けられているので、縁端効果が発現し易くなり、堆積量検出装置の検出感度が向上する。 In this way, the first electrode 32a and the second electrode 32b are comb-like in a plan view and are provided so as to mesh with each other through a predetermined gap, so that the edge effect is easily exhibited, and deposition The detection sensitivity of the quantity detection device is improved.

なお、第１電極３２ａおよび第２電極３２ｂは、平面視において互いに対向するように積層体３１の第１層３１１上に設けられていれば、その形状については特に限定されない。例えば、第１電極３２ａおよび第２電極３２ｂの形状は、上述した櫛歯状以外に、ミアンダ形状、２重らせん形状であってもよい。このような形状であっても、縁端効果が発現し易くなるので、堆積量検出装置の検出感度は向上する。 The shape of the first electrode 32a and the second electrode 32b is not particularly limited as long as the first electrode 32a and the second electrode 32b are provided on the first layer 311 of the stacked body 31 so as to face each other in plan view. For example, the shape of the first electrode 32a and the second electrode 32b may be a meander shape or a double helix shape other than the above-described comb shape. Even in such a shape, the edge effect is easily exhibited, so that the detection sensitivity of the deposition amount detection device is improved.

ここで、本実施形態に係る堆積量検知センサ３においては、積層体３１の第２層３１２の誘電率は、積層体３１の第１層３１１の誘電率よりも低くなるように構成されている。具体的には、積層体３１の第２層３１２には、図４に示すように、複数の閉気孔Ｃが形成されている。すなわち、誘電率がほぼ「１」である空気が閉気孔Ｃとして積層体３１の第２層３１２に複数形成されているため、積層体３１の第２層３１２の誘電率は、積層体３１の第１層３１１の誘電率よりも低くなる。このように、積層体３１の第２層３１２の誘電率は、積層体３１の第１層３１１の誘電率よりも低いので、堆積量検出装置の検出感度は向上する。なお、この理由については、後述する。 Here, in the accumulation amount detection sensor 3 according to the present embodiment, the dielectric constant of the second layer 312 of the multilayer body 31 is configured to be lower than the dielectric constant of the first layer 311 of the multilayer body 31. . Specifically, a plurality of closed pores C are formed in the second layer 312 of the laminate 31 as shown in FIG. That is, since a plurality of air having a dielectric constant of approximately “1” is formed in the second layer 312 of the multilayer body 31 as closed pores C, the dielectric constant of the second layer 312 of the multilayer body 31 is It becomes lower than the dielectric constant of the first layer 311. Thus, since the dielectric constant of the second layer 312 of the stacked body 31 is lower than the dielectric constant of the first layer 311 of the stacked body 31, the detection sensitivity of the deposition amount detection device is improved. This reason will be described later.

なお、複数の閉気孔Ｃは、例えば、次のようにして積層体３１の第２層３１２に形成される。すなわち、複数の樹脂ビーズを、積層体３１となるセラミック材料に予め混合しておく。そして、セラミック材料を樹脂ビーズとともに所定の温度で焼成することにより、樹脂ビーズを分解させる。このようにすると、樹脂ビーズが存在していた箇所が閉気孔となり、積層体３１の第２層３１２に複数の閉気孔Ｃが形成される。なお、これはあくまで一例であって、積層体３１の第２層３１２に複数の閉気孔Ｃを形成する方法については、特に限定されない。 The plurality of closed pores C are formed in the second layer 312 of the stacked body 31 as follows, for example. That is, a plurality of resin beads are mixed in advance with the ceramic material to be the laminate 31. Then, the ceramic beads are fired at a predetermined temperature together with the resin beads to decompose the resin beads. If it does in this way, the location where the resin bead existed will become a closed pore, and the several closed pore C will be formed in the 2nd layer 312 of the laminated body 31. FIG. This is merely an example, and the method for forming the plurality of closed pores C in the second layer 312 of the stacked body 31 is not particularly limited.

また、積層体３１の第１層３１１には、積層体３１の主面３１ａに堆積された粒子状物質を除去するための発熱体３３が埋設されている。発熱体３３は、図示しない発熱体制御部からの指示によって、発熱する。発熱体３３が発熱することにより、積層体３１の主面３１ａ上に堆積された粒子状物質が焼失する。これにより、積層体３１の主面３１ａ上に堆積された粒子状物質を除去することが可能となる。なお、発熱体制御部が発熱体３３を発熱させるタイミングについては、特に限定されない。例えば、積層体３１の主面３１ａ上に堆積された粒子状物質の堆積量が閾値を超えた場合に、発熱体制御部が発熱体３３を発熱させてもよいし、一定時間毎に、発熱体制御部が発熱体３３を発熱させてもよい。なお、積層体３１の主面３１ａ上に堆積された粒子状物質を除去する必要がない場合には、積層体３１の第１層３１１に発熱体３３を埋設しなくてもよい。 Further, in the first layer 311 of the stacked body 31, a heating element 33 for removing particulate matter deposited on the main surface 31a of the stacked body 31 is embedded. The heating element 33 generates heat in response to an instruction from a heating element control unit (not shown). When the heat generating body 33 generates heat, the particulate matter deposited on the main surface 31a of the laminated body 31 is burned out. Thereby, the particulate matter deposited on the main surface 31a of the multilayer body 31 can be removed. Note that the timing at which the heating element control unit causes the heating element 33 to generate heat is not particularly limited. For example, when the amount of particulate matter deposited on the main surface 31a of the laminate 31 exceeds a threshold value, the heating element controller may cause the heating element 33 to generate heat, or generate heat at regular intervals. The body control unit may cause the heating element 33 to generate heat. In addition, when it is not necessary to remove the particulate matter deposited on the main surface 31 a of the stacked body 31, the heating element 33 may not be embedded in the first layer 311 of the stacked body 31.

堆積量算出部４は、排気ガス中に含まれる粒子状物質が積層体３１の主面３１ａ上に堆積された堆積量を、第１電極３３ａおよび第２電極３３ｂ間の静電容量の変化に基づいて算出する。堆積量算出部４は、算出した堆積量を、制御部８へ出力する。 The deposition amount calculation unit 4 uses the deposition amount in which the particulate matter contained in the exhaust gas is deposited on the main surface 31a of the multilayer body 31 as a change in capacitance between the first electrode 33a and the second electrode 33b. Calculate based on The accumulation amount calculation unit 4 outputs the calculated accumulation amount to the control unit 8.

ところで、堆積量検出装置の検出感度を向上するためには、粒子状物質が堆積されていない場合と粒子状物質が堆積されている場合とにおける静電容量の変化率が大きいことが必要である。そこで、本発明者らは、積層体３１の第１層３１１の誘電率を「９」、粒子状物質の誘電率を「６」で固定し、積層体３１の第２層３１２の誘電率を「３」、「６」、「９」、「１２」、「１５」と順次変化させた場合の、粒子状物質が堆積されていない場合（厚み０ｍｍ）と粒子状物質が堆積されている場合（厚み０．１ｍｍ）とにおける静電容量の変化率を、シミュレーションにて測定した。その結果を図５に示す。 By the way, in order to improve the detection sensitivity of the deposition amount detection device, it is necessary that the rate of change in capacitance between the case where the particulate matter is not deposited and the case where the particulate matter is deposited is large. . Therefore, the present inventors fixed the dielectric constant of the first layer 311 of the laminate 31 to “9” and the dielectric constant of the particulate matter to “6”, and set the dielectric constant of the second layer 312 of the laminate 31 to “3”, “6”, “9”, “12”, “15”, when the particulate matter is not deposited (thickness 0 mm) and when the particulate matter is deposited The rate of change in capacitance with (thickness 0.1 mm) was measured by simulation. The result is shown in FIG.

図５に示すように、積層体３１の第２層３１２の誘電率が、積層体３１の第１層３１１の誘電率よりも低い場合に、静電容量の変化率が大きいことが判る。すなわち、図５では、積層体３１の第２層３１２の誘電率が「３」および「６」の場合である。なお、静電容量の変化率（％）は、静電容量の変化量を、粒子状物質が堆積されていない場合の静電容量の値で割り、その結果に対して１００を乗じることによって算出される。すなわち、堆積量検出装置の検出感度を向上するためには、積層体３１の第２層３１２の誘電率が、積層体３１の第１層３１１の誘電率よりも低くなることが必要である。 As shown in FIG. 5, it can be seen that when the dielectric constant of the second layer 312 of the multilayer body 31 is lower than the dielectric constant of the first layer 311 of the multilayer body 31, the capacitance change rate is large. That is, in FIG. 5, the dielectric constant of the second layer 312 of the multilayer body 31 is “3” and “6”. The rate of change in capacitance (%) is calculated by dividing the amount of change in capacitance by the value of capacitance when particulate matter is not deposited and multiplying the result by 100. Is done. That is, in order to improve the detection sensitivity of the deposition amount detection device, the dielectric constant of the second layer 312 of the stacked body 31 needs to be lower than the dielectric constant of the first layer 311 of the stacked body 31.

ここで、積層体３１の第２層３１２の誘電率が、積層体３１の第１層３１１の誘電率よりも低い場合に、静電容量の変化率が大きくなるのは、次の理由による。すなわち、積層体３１の第２層３１２の誘電率が低くなると、この第２層３１２の誘電率は、粒子状物質の誘電率と比較して、相対的に低くなる。つまり、第２層３１２の誘電率と粒子状物質の誘電率との和に対する粒子状物質の誘電率の割合が高くなる。そのため、積層体３１の第２層３１２の誘電率が、積層体３１の第１層３１１の誘電率よりも低い場合に、静電容量の変化率が大きくなり、堆積量検出装置の検出感度は向上する。 Here, when the dielectric constant of the 2nd layer 312 of the laminated body 31 is lower than the dielectric constant of the 1st layer 311 of the laminated body 31, the change rate of an electrostatic capacitance becomes large for the following reason. That is, when the dielectric constant of the second layer 312 of the stacked body 31 is lowered, the dielectric constant of the second layer 312 is relatively lower than the dielectric constant of the particulate matter. That is, the ratio of the dielectric constant of the particulate matter to the sum of the dielectric constant of the second layer 312 and the dielectric constant of the particulate matter is increased. Therefore, when the dielectric constant of the second layer 312 of the stacked body 31 is lower than the dielectric constant of the first layer 311 of the stacked body 31, the rate of change in capacitance increases, and the detection sensitivity of the deposition amount detection device is improves.

このため、本実施形態では、上述したように、積層体３１の第２層３１２に複数の閉気孔Ｃを形成することにより、積層体３１の第２層３１２の誘電率を、積層体３１の第１層３１１の誘電率よりも低くしている。 For this reason, in the present embodiment, as described above, by forming a plurality of closed pores C in the second layer 312 of the stacked body 31, the dielectric constant of the second layer 312 of the stacked body 31 is changed. The dielectric constant of the first layer 311 is lower.

流量センサ５は、排気通路Ｕを移動する排気ガスの流量を検出するためのセンサであって、フィルタ装置２よりも上流側（内燃機関側）の排気通路Ｕに設けられている。流量センサ５としては、例えば、熱式流量方式を用いた流量センサが挙げられる。なお、排気ガスの流量を検出できれば、流量センサ５の方式については、特に限定されない。 The flow rate sensor 5 is a sensor for detecting the flow rate of the exhaust gas that moves through the exhaust passage U, and is provided in the exhaust passage U upstream of the filter device 2 (internal combustion engine side). Examples of the flow sensor 5 include a flow sensor using a thermal flow method. Note that the method of the flow sensor 5 is not particularly limited as long as the flow rate of the exhaust gas can be detected.

流量算出部６は、流量センサ５により検出された情報に基づいて、排気通路Ｕを移動する排気ガスの流量を算出する。流量算出部６は、算出した排気ガスの流量を、制御部８へ出力する。 The flow rate calculation unit 6 calculates the flow rate of the exhaust gas moving through the exhaust passage U based on the information detected by the flow rate sensor 5. The flow rate calculation unit 6 outputs the calculated exhaust gas flow rate to the control unit 8.

なお、流量センサ５および流量算出部６が、本発明に係る流量検出装置の一実施形態となる。 The flow rate sensor 5 and the flow rate calculation unit 6 are an embodiment of the flow rate detection device according to the present invention.

ＥＣＵ７は、内燃機関における点火系と燃焼系とを制御するコントローラである。例えば、ＥＣＵ７は、後述する制御部８からの指示によって、内燃機関の回転数を低下あるいは上昇させ、または内燃機関の点火時期等を制御する。すなわち、ＥＣＵ７は、内燃機関における点火系と燃焼系とを制御することにより、排気ガス中に含まれる粒子状物質の数を制御することができる。 The ECU 7 is a controller that controls an ignition system and a combustion system in the internal combustion engine. For example, the ECU 7 reduces or increases the rotational speed of the internal combustion engine or controls the ignition timing of the internal combustion engine, etc., according to an instruction from the control unit 8 described later. That is, the ECU 7 can control the number of particulate matter contained in the exhaust gas by controlling the ignition system and the combustion system in the internal combustion engine.

制御部８は、流量算出部６により算出された排気ガスの流量と、堆積量算出部４により算出された粒子状物質の堆積量とに基づいて、単位時間当たりに移動した排気ガス中に、フィルタ装置２で捕集できなかった粒子状物質がどのくらい含まれていたかを示す捕集不可量を算出する。制御部８は、算出した捕集不可量に基づいて、ＥＣＵ７に対して指示する。例えば、制御部８は、算出した捕集不可量が閾値以上であれば、排気ガス中に含まれる粒子状物質の数が減少するように、ＥＣＵ７に対して指示する。なお、制御部８は、ＥＣＵ７に対して指示することなく、算出した捕集不可量を、単にディスプレイに表示するようにしてもよい。 Based on the flow rate of the exhaust gas calculated by the flow rate calculation unit 6 and the deposition amount of the particulate matter calculated by the deposition amount calculation unit 4, the control unit 8 includes, in the exhaust gas moved per unit time, An uncollectable amount indicating how much particulate matter that could not be collected by the filter device 2 was included is calculated. The control unit 8 instructs the ECU 7 based on the calculated uncollectable amount. For example, the control unit 8 instructs the ECU 7 to reduce the number of particulate matter contained in the exhaust gas if the calculated uncollectable amount is equal to or greater than a threshold value. The control unit 8 may simply display the calculated uncollectable amount on the display without instructing the ECU 7.

以上のように、本実施形態に係る堆積量検出装置は、上記従来の堆積量検出装置と比較して、検出感度を向上することができる。 As described above, the deposition amount detection device according to the present embodiment can improve the detection sensitivity as compared with the conventional deposition amount detection device.

なお、上述した実施形態は、本発明の実施形態の一具体例を示すものであり、種々の変更が可能である。以下、いくつかの主な変更例を示す。 The above-described embodiment shows a specific example of the embodiment of the present invention, and various modifications can be made. The following are some major changes.

[変更例１]
上述した実施形態では、積層体３１の第２層３１２に形成された複数の気孔の全てが、閉気孔Ｃである場合について説明したが、これに限定されない。すなわち、積層体３１の第２層３１２に形成される複数の気孔のうち一部の気孔は、開気孔であってもよい。但し、積層体３１の第２層３１２に開気孔を形成した場合、この開気孔を通じて粒子状物質が第１電極３２ａおよび第２電極３２ｂに付着し、第１電極３２ａおよび第２電極３２ｂが腐食してしまう可能性がある。このため、積層体３１の第２層３１２に開気孔を形成する場合には、第１電極３２ａおよび第２電極３２ｂは、耐腐食性の高い、例えば、金または白金等の金属材料を用いて構成することが必要である。 [Modification 1]
In the above-described embodiment, the case where all of the plurality of pores formed in the second layer 312 of the stacked body 31 are closed pores C has been described, but the present invention is not limited to this. That is, some of the plurality of pores formed in the second layer 312 of the stacked body 31 may be open pores. However, when open pores are formed in the second layer 312 of the laminate 31, particulate matter adheres to the first electrode 32a and the second electrode 32b through the open pores, and the first electrode 32a and the second electrode 32b corrode. There is a possibility that. For this reason, when forming open pores in the second layer 312 of the laminate 31, the first electrode 32a and the second electrode 32b are made of a metal material having high corrosion resistance, such as gold or platinum. It is necessary to configure.

逆に言えば、上述した実施形態のように、積層体３１の第２層３１２に形成される複数の気孔の全てが閉気孔Ｃである場合には、第１電極３２ａおよび第２電極３２ｂの構成材料として、耐腐食性の高い材料を選択する必要がなく、材料選定の自由度が向上する。 In other words, when all of the plurality of pores formed in the second layer 312 of the stacked body 31 are closed pores C as in the above-described embodiment, the first electrode 32a and the second electrode 32b As a constituent material, it is not necessary to select a material having high corrosion resistance, and the degree of freedom in material selection is improved.

[変更例２]
上述した実施形態では、積層体３１の第２層３１２の誘電率を、積層体３１の第１層３１１の誘電率よりも低くするために、積層体３１の第２層３１２に複数の閉気孔Ｃを形成する例について説明したが、これに限定されない。すなわち、積層体３１の第２層３１２に、積層体３１の誘電率よりも低い誘電率を有する材料からなる物質を複数含有させてもよい。つまり、積層体３１の第２層３１２には、積層体３１の第１層３１１の誘電率と同じ誘電率を有する第１物質と、当該第１物質内に含有されており、かつ積層体３１の第１層３１１の誘電率よりも低い誘電率を有する第２物質とを有している。積層体３１の誘電率よりも低い誘電率を有する材料としては、例えば、二酸化ケイ素（ＳｉＯ_２）、高耐熱エポキシ樹脂等が挙げられる。 [Modification 2]
In the embodiment described above, a plurality of closed pores are formed in the second layer 312 of the multilayer body 31 in order to make the dielectric constant of the second layer 312 of the multilayer body 31 lower than the dielectric constant of the first layer 311 of the multilayer body 31. Although the example which forms C was demonstrated, it is not limited to this. In other words, the second layer 312 of the stacked body 31 may contain a plurality of substances made of a material having a dielectric constant lower than that of the stacked body 31. In other words, the second layer 312 of the stacked body 31 contains the first substance having the same dielectric constant as that of the first layer 311 of the stacked body 31, and is contained in the first substance. And a second material having a dielectric constant lower than that of the first layer 311. Examples of the material having a dielectric constant lower than that of the laminated body 31 include silicon dioxide (SiO ₂ ) and a high heat-resistant epoxy resin.

[変更例３]
上述した実施形態では、積層体３１の第２層３１２の誘電率を、積層体３１の第１層３１１の誘電率よりも低くするために、積層体３１の第２層３１２に複数の閉気孔Ｃを形成する例について説明したが、これに限定されない。すなわち、図６に示すように、積層体３１の第２層３１２に、中空Ｓを形成してもよい。ここで、この中空Ｓは、第１電極３２ａおよび第２電極３２ｂを個別に覆うように形成されている。すなわち、誘電率がほぼ「１」である空気が中空Ｓとして積層体３１の第２層３１２に形成されているため、上述の実施形態と同様、積層体３１の第２層３１２の誘電率を、積層体３１の第１層３１１の誘電率よりも低くすることができる。 [Modification 3]
In the embodiment described above, a plurality of closed pores are formed in the second layer 312 of the multilayer body 31 in order to make the dielectric constant of the second layer 312 of the multilayer body 31 lower than the dielectric constant of the first layer 311 of the multilayer body 31. Although the example which forms C was demonstrated, it is not limited to this. That is, as shown in FIG. 6, a hollow S may be formed in the second layer 312 of the stacked body 31. Here, the hollow S is formed so as to individually cover the first electrode 32a and the second electrode 32b. That is, since air having a dielectric constant of approximately “1” is formed as the hollow S in the second layer 312 of the multilayer body 31, the dielectric constant of the second layer 312 of the multilayer body 31 is set as in the above-described embodiment. The dielectric constant of the first layer 311 of the stacked body 31 can be made lower.

[変更例４]
なお、排気ガス中に含まれる粒子状物質に静電気を付与するとともに、積層体３１の第１層３１１に静電気吸着部材を設けることにより、積層体３１の主面３１ａに粒子状物質が容易に堆積されるようにしてもよい。例えば、粒子状物質にマイナスの電荷を付与するとともに、積層体３１の第１層３１１にプラスの静電気吸着部材を設ければ、積層体３１の主面３１ａには粒子状物質が堆積され易くなる。 [Modification 4]
In addition, while applying static electricity to the particulate matter contained in the exhaust gas, and providing the electrostatic adsorption member on the first layer 311 of the laminate 31, the particulate matter is easily deposited on the main surface 31a of the laminate 31. You may be made to do. For example, when a negative charge is applied to the particulate matter and a positive electrostatic adsorption member is provided on the first layer 311 of the laminate 31, the particulate matter is easily deposited on the main surface 31a of the laminate 31. .

１検出システム
２フィルタ装置
３堆積量検知センサ
３１積層体
３１ａ主面
３１１積層体の第１層
３１２積層体の第２層
３２ａ第１電極
３２ｂ第２電極
３３発熱体
４堆積量算出部
５流量センサ
６流量算出部
８制御部
Ｕ排気通路
Ｃ閉気孔
Ｓ中空 DESCRIPTION OF SYMBOLS 1 Detection system 2 Filter apparatus 3 Accumulation amount detection sensor 31 Laminated body 31a Main surface 311 1st layer 312 of laminated body 2nd layer 32a of laminated body 1st electrode 32b 2nd electrode 33 Heating body 4 Deposition amount calculation part 5 Flow rate sensor 6 Flow rate calculation unit 8 Control unit U Exhaust passage C Closed pore S Hollow

Claims

A laminated body provided in an exhaust passage through which exhaust gas of the internal combustion engine moves, and having a main surface;
A pair of electrodes embedded in the laminate;
A deposition amount calculation unit that calculates a deposition amount in which particulate matter contained in the exhaust gas is deposited on the main surface of the laminate based on a change in capacitance between the pair of electrodes;
The laminate has at least a first layer and a second layer laminated on the first layer,
The pair of electrodes are provided on the first layer of the laminate so as to face each other in plan view, and are covered with the second layer of the laminate,
The deposition amount detection apparatus according to claim 1, wherein a dielectric constant of the second layer of the multilayer body is lower than a dielectric constant of the first layer of the multilayer body.

The deposition amount detection apparatus according to claim 1, wherein a plurality of pores are formed in the second layer of the stacked body.

The accumulation amount detection apparatus according to claim 2, wherein all of the plurality of pores formed in the second layer of the stacked body are closed pores.

Some of the plurality of pores formed in the second layer of the laminate are open pores,
The deposition amount detection device according to claim 2, wherein the electrode is made of gold or platinum.

The second layer of the stacked body includes a first material having the same dielectric constant as that of the first layer of the stacked body, and the first layer of the stacked body is contained in the first material. The deposition amount detection device according to claim 1, further comprising: a second substance having a dielectric constant lower than that of the first material.

The deposition amount detection device according to claim 1, wherein a hollow is formed in the second layer of the stacked body.

The deposition amount detection device according to claim 6, wherein the hollow formed in the second layer of the stacked body is formed so as to individually cover the pair of electrodes.

The deposition according to any one of claims 1 to 7, wherein a heating element for removing particulate matter deposited on the main surface of the laminate is embedded in the first layer of the laminate. Quantity detection device.

The laminate is made of a ceramic material,
The deposition amount detection device according to claim 1, wherein the stacked body is configured by simultaneously firing the first layer and the second layer.

A filter device that is provided in the exhaust passage and collects particulate matter contained in the exhaust gas;
The detection system provided with the deposition amount detection apparatus as described in any one of Claims 1-9 which detects the deposition amount of the particulate matter which could not be collected with the said filter apparatus.

A flow rate detection device for detecting a flow rate of exhaust gas moving in the exhaust passage;
Based on the flow rate of the exhaust gas detected by the flow rate detection device and the deposition amount of the particulate matter detected by the deposition amount detection device, in the exhaust gas moved per unit time, the filter device The detection system according to claim 10, further comprising a control device that calculates an uncollectable amount indicating how much particulate matter that could not be collected was contained.