JP2007182810A - Exhaust emission control device - Google Patents

Exhaust emission control device Download PDF

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JP2007182810A
JP2007182810A JP2006001678A JP2006001678A JP2007182810A JP 2007182810 A JP2007182810 A JP 2007182810A JP 2006001678 A JP2006001678 A JP 2006001678A JP 2006001678 A JP2006001678 A JP 2006001678A JP 2007182810 A JP2007182810 A JP 2007182810A
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exhaust gas
honeycomb structure
outer peripheral
electrode
rod
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Akira Mizuno
彰 水野
Masaru Kakihana
大 垣花
Hiroto Hirata
裕人 平田
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Toyohashi University of Technology NUC
Toyota Motor Corp
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Toyohashi University of Technology NUC
Toyota Motor Corp
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  • Physical Or Chemical Processes And Apparatus (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device improved in energy efficiency, PM collection efficiency and the like. <P>SOLUTION: The exhaust emission control device has an insulative honeycomb structural body, an outer peripheral electrode disposed on an outer peripheral part of the honeycomb structural body and a bar electrode disposed on a central axis of the honeycomb structural body. The outer peripheral electrode and bar electrode are extended to an upstream side of exhaust gas flow in the honeycomb structural body. A plurality of discharge projections are provided on the part of the bar electrode, which is extended to the exhaust gas flow upstream side of the honeycomb structural body, and an insulative member is disposed on an inner peripheral surface of the part of the outer peripheral electrode, which is extended to the exhaust gas flow upstream side of the honeycomb structural body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、プラズマ放電を利用して内燃機関等からの排ガス中の有害成分、特に粒子状物質(以後PMとする)を除去するための排ガス浄化装置に関する。   The present invention relates to an exhaust gas purifying apparatus for removing harmful components, particularly particulate matter (hereinafter referred to as PM), in exhaust gas from an internal combustion engine or the like by using plasma discharge.

自動車等において使用される内燃機関や焼却設備から排出される排ガスには、様々な有害成分が含有されている。この有害成分のうち、特にNOx、SOx、及びPMの排出を低減させることが望まれている。ディーゼルエンジンでは。近年特にPMの排出を低減することが強く望まれており、このPMを除去するためにパティキュレートフィルターが用いられている。   Various harmful components are contained in exhaust gas discharged from internal combustion engines and incineration facilities used in automobiles and the like. Of these harmful components, it is desired to reduce NOx, SOx, and PM emissions. For diesel engines. In recent years, in particular, it has been strongly desired to reduce the emission of PM, and a particulate filter is used to remove this PM.

この種のパティキュレートフィルターは、コージェライト等のセラミックからなる多孔質のハニカム構造となっており、格子状に区画された各流路の入口が交互に目封じされ、入口が目封じされていない流路においては出口が目封じされており、各流路を区画する多孔質壁を透過した排ガスのみが下流側へ排出される。そして、排ガス中のPMは前記多孔質壁を通過することができないため、この多孔質壁の内側表面においてPMが捕集される。   This type of particulate filter has a porous honeycomb structure made of ceramics such as cordierite, and the inlets of each flow path partitioned in a lattice pattern are alternately sealed, and the inlets are not sealed. The outlets are sealed in the flow paths, and only the exhaust gas that has permeated through the porous walls that define each flow path is discharged downstream. Since PM in the exhaust gas cannot pass through the porous wall, PM is collected on the inner surface of the porous wall.

このようなフィルターでは、捕集されたPMによりフィルターが目詰まりを起こし、通気抵抗が増加し、エンジンに負担をかける結果となるため、この目詰まりによる通気抵抗が増加する前にPMを適宜に燃焼除去し、フィルターの再生を図る必要がある。ところが、通常のディーゼルエンジンの運転状態では、PMが自己燃焼するほどの高い排気温度が得られない。   In such a filter, the collected PM causes the filter to be clogged, resulting in an increase in ventilation resistance and a burden on the engine. Therefore, before the ventilation resistance due to this clogging increases, the PM is appropriately adjusted. It is necessary to burn off and regenerate the filter. However, in the normal operation state of a diesel engine, an exhaust temperature that is high enough to cause PM to self-combust is not obtained.

そこで最近、放電によってプラズマを発生させ、このプラズマの酸化作用によってPMを燃焼除去し、かつプラズマの酸化作用と触媒の還元作用によってNOx等を浄化する排ガス浄化装置(プラズマリアクター)が提案されている。   Therefore, recently, an exhaust gas purifying apparatus (plasma reactor) has been proposed that generates plasma by discharge, burns and removes PM by the oxidizing action of the plasma, and purifies NOx and the like by the oxidizing action of the plasma and the reducing action of the catalyst. .

図1に、従来の排ガス浄化装置の1例を示す。この排ガス浄化装置10は、内燃機関の排気系統を構成する排気管L1とL2の間に組み込まれるケース11を有し、このケース11の内部に排ガスが導入される。そしてケース11の内部には、ハニカム構造体12、外周電極13、及び棒状電極14が配置されている。棒状電極14には電源15が接続され、外周電極13は接地されており、電源15を作用させることにより、棒状電極14と外周電極13の間で放電を起こさせ、プラズマを発生させる。   FIG. 1 shows an example of a conventional exhaust gas purification device. The exhaust gas purification apparatus 10 has a case 11 that is incorporated between exhaust pipes L1 and L2 that constitute an exhaust system of an internal combustion engine, and exhaust gas is introduced into the case 11. In the case 11, the honeycomb structure 12, the outer peripheral electrode 13, and the rod-shaped electrode 14 are disposed. A power source 15 is connected to the rod-shaped electrode 14, and the outer peripheral electrode 13 is grounded. When the power source 15 is operated, a discharge is generated between the rod-shaped electrode 14 and the outer peripheral electrode 13 to generate plasma.

このような排ガス浄化装置において、電極間にスパークが発生することによる無駄なエネルギー消費を回避するため、電極間に電気絶縁性の中空筒体を設置することが提案されている(特許文献1参照)。   In such an exhaust gas purifying apparatus, it has been proposed to install an electrically insulating hollow cylinder between the electrodes in order to avoid unnecessary energy consumption due to the occurrence of sparks between the electrodes (see Patent Document 1). ).

特開2001−162134号公報JP 2001-162134 A

しかしながら、上記の排ガス浄化装置では、エネルギー効率、PM捕集効率等の点で改善の余地がある。本発明は、このような問題を解消し、エネルギー効率、PM捕集効率等を改善した排ガス浄化装置を提供することを目的とする。   However, the above exhaust gas purification apparatus has room for improvement in terms of energy efficiency, PM collection efficiency, and the like. An object of the present invention is to provide an exhaust gas purifying apparatus that solves such problems and improves energy efficiency, PM collection efficiency, and the like.

上記問題点を解決するために1番目の発明によれば、
絶縁性ハニカム構造体、
前記ハニカム構造体の外周部に配置された外周電極、及び
前記ハニカム構造体の中心軸上に配置された棒状電極
を有する排ガス浄化装置において、前記外周電極及び棒状電極を、前記ハニカム構造体の排ガス流れ上流側にまで延在させ、前記棒状電極の、前記ハニカム構造体の排ガス流れ上流側に延在している部位に複数の放電突起を設け、前記外周電極の、前記ハニカム構造体の排気流れ上流側に延在している部位の内周面上に絶縁部材を配置している。
In order to solve the above problem, according to the first invention,
Insulating honeycomb structure,
In the exhaust gas purifying apparatus having an outer peripheral electrode disposed on an outer peripheral portion of the honeycomb structure and a rod-shaped electrode disposed on a central axis of the honeycomb structure, the outer electrode and the rod-shaped electrode are connected to the exhaust gas of the honeycomb structure. A plurality of discharge protrusions are provided in a portion of the rod-shaped electrode that extends to the upstream side of the flow and extends to the upstream side of the exhaust gas flow of the honeycomb structure, and the exhaust flow of the honeycomb structure of the outer peripheral electrode An insulating member is disposed on the inner peripheral surface of the portion extending upstream.

上記問題点を解決するために2番目の発明によれば、
絶縁性ハニカム構造体、
前記ハニカム構造体の外周部に配置された外周電極、及び
前記ハニカム構造体の中心軸上に配置された棒状電極
を有し、前記外周電極及び棒状電極が、前記ハニカム構造体の排ガス流れ上流側にまで延在しており、前記棒状電極が、前記ハニカム構造体の排ガス流れ上流側に延在している部位に複数の放電突起を有し、前記外周電極の、前記ハニカム構造体の排気流れ上流側に延在している部位の内周面上に絶縁部材が配置されている処理ユニットを、排ガス流れの上流から下流に向かって直列に複数配置している。
According to the second invention to solve the above problem,
Insulating honeycomb structure,
An outer peripheral electrode disposed on an outer peripheral portion of the honeycomb structure; and a rod-shaped electrode disposed on a central axis of the honeycomb structure, wherein the outer peripheral electrode and the rod-shaped electrode are upstream of the exhaust gas flow of the honeycomb structure The rod-shaped electrode has a plurality of discharge protrusions at a portion extending upstream of the exhaust gas flow of the honeycomb structure, and the exhaust gas flow of the honeycomb structure of the outer peripheral electrode A plurality of processing units in which insulating members are arranged on the inner peripheral surface of the portion extending upstream are arranged in series from the upstream side to the downstream side of the exhaust gas flow.

本発明によれば、外周電極と棒状電極の間に絶縁部材を配置することにより、電極間におけるスパーク発生を防止し、PM堆積による電極間の短絡を防止し、エネルギー効率及びPM捕集効率を向上させることができる。また、棒状電極に放電突起を設けることにより、電子放出を促進し、エネルギー効率を向上させることができる。さらに、これらを組み合わせることにより、PMはハニカム構造体に達する前に、排ガス流れ上流側の棒状電極と絶縁部材の間に発生したマイクロディスチャージにより帯電してハニカム構造体で捕集され、排ガスは活性化されてPM酸化を促進させることができる。また、このような構成からなるユニットを複数組み合わせることにより、特に下流側のユニットにおけるPM堆積を防止し、PM酸化を促進することができる。   According to the present invention, by disposing an insulating member between the outer peripheral electrode and the rod-shaped electrode, it is possible to prevent the occurrence of sparks between the electrodes, to prevent a short circuit between the electrodes due to PM deposition, and to improve energy efficiency and PM collection efficiency. Can be improved. Further, by providing discharge protrusions on the rod-like electrode, it is possible to promote electron emission and improve energy efficiency. Furthermore, by combining these, before reaching the honeycomb structure, PM is charged by the micro discharge generated between the rod-shaped electrode upstream of the exhaust gas flow and the insulating member and collected by the honeycomb structure, and the exhaust gas is activated. To promote PM oxidation. Further, by combining a plurality of units having such a configuration, it is possible to prevent PM accumulation, particularly in the downstream unit, and promote PM oxidation.

以下、本発明の排ガス浄化装置の一態様を図面を参照して説明する。この排ガス浄化装置20は、図2に示すように、ハニカム構造体22、このハニカム構造体22の外周部に配置された外周電極23、及びこのハニカム構造体22の中心軸上に配置された棒状電極24を有する。   Hereinafter, one mode of an exhaust gas purification apparatus of the present invention will be described with reference to the drawings. As shown in FIG. 2, the exhaust gas purification device 20 includes a honeycomb structure 22, an outer peripheral electrode 23 disposed on the outer peripheral portion of the honeycomb structure 22, and a rod-shaped member disposed on the central axis of the honeycomb structure 22. It has an electrode 24.

ここで外周電極23及び棒状電極24は、ハニカム構造体22の排ガス流れ上流側にまで延在しており、棒状電極24は、ハニカム構造体22の排ガス流れ上流側に延在している部位に複数の放電突起27を有し、外周電極23の、ハニカム構造体22の排気流れ上流側に延在している部位の内周面上に絶縁部材26が配置されている。   Here, the outer peripheral electrode 23 and the rod-shaped electrode 24 extend to the upstream side of the exhaust gas flow of the honeycomb structure 22, and the rod-shaped electrode 24 extends to the portion of the honeycomb structure 22 that extends to the upstream side of the exhaust gas flow. An insulating member 26 is disposed on the inner peripheral surface of a portion having a plurality of discharge protrusions 27 and extending to the exhaust gas upstream side of the honeycomb structure 22 of the outer peripheral electrode 23.

棒状電極24は電源25に接続され、外周電極23は接地されているが、これを逆にし、棒状電極24を接地し、外周電極23を電源に接続してもよい。あるいは、棒状電極24と外周電極23を電源25の異なる極に接続してもよい。棒状電極24は、ハニカム構造体22の半径方向中央部分の排ガス流れ下流側に残っているハニカム構造体に固定されている。   The rod electrode 24 is connected to the power source 25 and the outer peripheral electrode 23 is grounded. However, the rod electrode 24 may be grounded and the outer peripheral electrode 23 may be connected to the power source. Alternatively, the rod-shaped electrode 24 and the outer peripheral electrode 23 may be connected to different poles of the power source 25. The rod-shaped electrode 24 is fixed to the honeycomb structure remaining on the downstream side of the exhaust gas flow in the radial center portion of the honeycomb structure 22.

この排ガス浄化装置20は、ケース21に収納し、内燃機関の排気系統を構成する排気管に接続されるが、ケース21を金属製とし、外周電極として用いてもよい。PMを含む排ガスは、矢印で示すように、図の左側から右側に流れ、外周電極23に囲まれたハニカム構造体22を通過する。   The exhaust gas purification device 20 is housed in a case 21 and connected to an exhaust pipe constituting an exhaust system of an internal combustion engine. However, the case 21 may be made of metal and used as an outer peripheral electrode. The exhaust gas containing PM flows from the left side to the right side of the drawing as shown by the arrow, and passes through the honeycomb structure 22 surrounded by the outer peripheral electrode 23.

ここで、排ガス浄化装置20を構成する各構成部について具体的に説明する。
絶縁性ハニカム構造体22は、コージェライトやアルミナ等のセラミックにより形成されており、排ガスの流れ方向に延在する多数のセルを有している。このハニカム構造体22は、ストレートフロー型であってもウォールフロー型であってもよい。ここでこのハニカム構造体22は、十分な絶縁性を有し、それによってPMよりも導電性が小さいようにし、電圧を印加したときにPM自体に電流が流れてPMが通電燃焼されるようにすべきである。
Here, each component which comprises the exhaust gas purification apparatus 20 is demonstrated concretely.
The insulating honeycomb structure 22 is formed of a ceramic such as cordierite or alumina, and has a large number of cells extending in the flow direction of the exhaust gas. The honeycomb structure 22 may be a straight flow type or a wall flow type. Here, the honeycomb structure 22 has sufficient insulation, so that the conductivity is smaller than that of the PM, and when a voltage is applied, a current flows through the PM itself so that the PM is energized and combusted. Should.

このハニカム構造体22は、円筒形に成形された通常のハニカム担体の一部を研削して成形することができるが、所望の形状が得られるのであれば、任意の他の方法で製造してよい。また、このハニカム構造体22のセル壁には、CeO2、Pt/CeO2、Mn/CeO2、Fe/CeO2、Pt/Al23等の酸化触媒を担持させておいてもよい。 The honeycomb structure 22 can be formed by grinding a part of a normal honeycomb carrier formed into a cylindrical shape, but may be manufactured by any other method as long as a desired shape can be obtained. Good. In addition, an oxidation catalyst such as CeO 2 , Pt / CeO 2 , Mn / CeO 2 , Fe / CeO 2 , and Pt / Al 2 O 3 may be supported on the cell walls of the honeycomb structure 22.

棒状電極24は、この棒状電極24と外周電極23の間に電圧を印加することができる材料で形成する。この材料としては、導電性の材料や半導体等の材料を使用することができるが、なかでも金属材料が好ましい。この金属材料としては、具体的には銅、タングステン、ステンレス、鉄、白金、アルミニウム等を使用することができ、特にステンレスがコスト及び耐久性の点から好ましい。この棒状電極24の形状は、ワイヤが一般的であるが、中空の棒状電極も使用することができる。   The rod-shaped electrode 24 is formed of a material capable of applying a voltage between the rod-shaped electrode 24 and the outer peripheral electrode 23. As this material, a conductive material or a material such as a semiconductor can be used, and among these, a metal material is preferable. Specifically, copper, tungsten, stainless steel, iron, platinum, aluminum or the like can be used as the metal material, and stainless steel is particularly preferable from the viewpoint of cost and durability. The shape of the rod-shaped electrode 24 is generally a wire, but a hollow rod-shaped electrode can also be used.

この棒状電極24は、ハニカム構造体22内から排ガス流れ上流側に突出して延在している部位には設けられている放電突起27は、棒状電極24と同様の材料から形成することができ、その形状は複数の針を棘状に形成されており、棒状電極24から放射状に、その先端が外周電極23に向くように配置されている。この放電突起27の針状部の数はある程度異常必要であるが、排気ガス中のPMを最も良好に帯電させるように、最適化した数を実験により定めることができる。   The rod-shaped electrode 24 can be formed of the same material as that of the rod-shaped electrode 24, and the discharge projection 27 provided at a portion extending and projecting from the honeycomb structure 22 to the upstream side of the exhaust gas flow. The plurality of needles are formed in a spine shape, and are arranged radially from the rod-shaped electrode 24 so that the tip thereof faces the outer peripheral electrode 23. Although the number of needle-like portions of the discharge protrusion 27 needs to be abnormal to some extent, an optimized number can be determined by experiment so as to charge the PM in the exhaust gas most satisfactorily.

外周電極23は、棒状電極24と同様の材料を、金属メッシュもしくは金属箔としてハニカム構造体22に巻きつけて円筒状に形成される。あるいは、導電性ペーストをハニカム構造体22に適用して形勢することもできる。   The outer peripheral electrode 23 is formed in a cylindrical shape by winding the same material as the rod-shaped electrode 24 around the honeycomb structure 22 as a metal mesh or a metal foil. Alternatively, the conductive paste can be applied to the honeycomb structure 22 and formed.

電源25は、パルス状又は定常の直流電圧を発生させるものでよい。印加電圧及びパルス周期としては、プラズマを発生させるのに一般的な値を使用することができ、例えばパルス電圧50kV、パルス周期2,000Hzを使用することができる。   The power supply 25 may generate a pulsed or steady DC voltage. As the applied voltage and the pulse period, general values for generating plasma can be used. For example, a pulse voltage of 50 kV and a pulse period of 2,000 Hz can be used.

外周電極23の、ハニカム構造体22の排気流れ上流側に延在している部位の内周面上に設けられている絶縁部材26は、ハニカム構造体22と同様のセラミック等より、円筒状に形成することができる。この絶縁部材26は多孔質であることが好ましく、その細孔径は15〜200μmであることがより好ましい。   The insulating member 26 provided on the inner peripheral surface of the portion of the outer peripheral electrode 23 that extends to the upstream side of the exhaust flow of the honeycomb structure 22 is formed in a cylindrical shape from a ceramic or the like similar to the honeycomb structure 22. Can be formed. The insulating member 26 is preferably porous, and the pore diameter is more preferably 15 to 200 μm.

以上のように、棒状電極24に放電突起27を設けることにより、印加電圧を低減させ、エネルギー効率を向上させることができる。具体的には、図1に示すような従来の排ガス浄化装置において、PM捕集率95%を達成するに必要な印加電圧は30kVであったが、棒状電極に放電突起を設けることにより、この印加電圧は17kVに低下した。また、絶縁部材26を設けることにより、棒状電極24と外周電極23の間の短絡発生を抑制することができる。すなわち、図3に示すように、このような絶縁部材を配置していない従来の排ガス浄化装置では、PM16が堆積することに伴い、棒状電極14と外周電極13の間がPM16によって短絡し、回路が形成され、絶縁が破壊される。するともはや放電することができなくなり、PMの捕集率、排ガス浄化率が低下してしまう。そこで、図2に示すように、外周電極23の内周囲面上に絶縁部材を配置することにより、PMの堆積による外周電極23と棒状電極24の間の短絡を防ぐことができる。   As described above, by providing the discharge protrusion 27 on the rod-shaped electrode 24, the applied voltage can be reduced and the energy efficiency can be improved. Specifically, in the conventional exhaust gas purification apparatus as shown in FIG. 1, the applied voltage required to achieve a PM collection rate of 95% was 30 kV. The applied voltage dropped to 17 kV. Further, the provision of the insulating member 26 can suppress the occurrence of a short circuit between the rod-shaped electrode 24 and the outer peripheral electrode 23. That is, as shown in FIG. 3, in the conventional exhaust gas purifying apparatus in which such an insulating member is not arranged, the PM 16 is deposited, so that the rod-shaped electrode 14 and the outer peripheral electrode 13 are short-circuited by the PM 16 and the circuit Is formed and the insulation is destroyed. Then, it can no longer be discharged, and the PM collection rate and the exhaust gas purification rate are reduced. Therefore, as shown in FIG. 2, by arranging an insulating member on the inner peripheral surface of the outer peripheral electrode 23, a short circuit between the outer peripheral electrode 23 and the rod-shaped electrode 24 due to PM deposition can be prevented.

さらに本発明では、棒状電極24に放電突起27を設け、外周電極23の内周囲面上に絶縁部材26を設けることにより、マイクロディスチャージを発生させ、PM酸化を促進することができる。具体的には、図4に示すように、棒状電極24を負極とした場合、絶縁部材26には放電した電荷と逆の極性の電荷が集まり、その後、この絶縁部材26から逆に放電現象が起こり、排ガスを活性化し、PM酸化を促進することになる。   Furthermore, in the present invention, the discharge protrusion 27 is provided on the rod-shaped electrode 24 and the insulating member 26 is provided on the inner peripheral surface of the outer peripheral electrode 23, whereby microdischarge can be generated and PM oxidation can be promoted. Specifically, as shown in FIG. 4, when the rod-shaped electrode 24 is a negative electrode, charges having a polarity opposite to the discharged charge are collected in the insulating member 26, and then a discharge phenomenon is reversed from the insulating member 26. Occurs and activates the exhaust gas and promotes PM oxidation.

本発明の第二の態様では、上記の排ガス浄化装置を1つの処理ユニットとし、この処理ユニットを排ガス流れの上流から下流に向かって直列に複数配置している。具体的には、図5に示すように、この排ガス浄化装置50は、処理ユニット51をケース52内に、排ガス流れの上流から下流に向かって直列に複数配置している。各処理ユニット51は、絶縁性ハニカム構造体53、前記ハニカム構造体の外周部に配置された外周電極54、及び前記ハニカム構造体の中心軸上に配置された棒状電極55を有し、前記外周電極54及び棒状電極55が、前記各ハニカム構造体53の排ガス流れ上流側にまで延在しており、前記棒状電極55が、前記各ハニカム構造体53の排ガス流れ上流側に延在している部位に複数の放電突起56を有し、前記外周電極54の、前記各ハニカム構造体53の排気流れ上流側に延在している部位の内周面上に絶縁部材57が配置されている。   In the second aspect of the present invention, the exhaust gas purifying apparatus is a single processing unit, and a plurality of the processing units are arranged in series from the upstream side to the downstream side of the exhaust gas flow. Specifically, as shown in FIG. 5, in the exhaust gas purifying apparatus 50, a plurality of processing units 51 are arranged in series in a case 52 from upstream to downstream of the exhaust gas flow. Each processing unit 51 includes an insulating honeycomb structure 53, an outer peripheral electrode 54 disposed on an outer peripheral portion of the honeycomb structure, and a rod-shaped electrode 55 disposed on a central axis of the honeycomb structure. The electrode 54 and the rod-shaped electrode 55 extend to the exhaust gas flow upstream side of each honeycomb structure 53, and the rod-shaped electrode 55 extends to the exhaust gas flow upstream side of each honeycomb structure 53. A plurality of discharge protrusions 56 are provided at a part, and an insulating member 57 is disposed on the inner peripheral surface of the outer peripheral electrode 54 that extends to the upstream side of the exhaust flow of each honeycomb structure 53.

上記のように、放電突起と絶縁部材との間でマイクロチャージを発生させることにより排ガスをより活性化させることができるが、この活性化の間にもPMはハニカム構造体に堆積し、その堆積によって経時的に排ガス浄化能は低下する。そこで、ハニカム構造体を分割し、複数のユニットの繰り返し構造とすることにより、特に下流側のユニットではPM堆積が少なく、清浄面を保つことができ、排ガス浄化能を高く維持することができる。   As described above, the exhaust gas can be more activated by generating a micro charge between the discharge protrusion and the insulating member, but PM is also deposited on the honeycomb structure during this activation, and the deposition As a result, the exhaust gas purification ability decreases with time. Therefore, by dividing the honeycomb structure to form a repetitive structure of a plurality of units, particularly in the downstream unit, PM deposition is small, a clean surface can be maintained, and exhaust gas purification performance can be maintained high.

PM酸化速度試験及びPM捕集率測定試験
図6に示す構成の実験装置を用い、エンジン運転条件:回転数=1800rpm、トルク=30N・m、入りガス温度:200℃にて、以下のようにしてPM酸化速度及びPM捕集率を測定した。
PM oxidation rate test and PM collection rate measurement test Using the experimental apparatus shown in Fig. 6, the engine operating conditions were: rotation speed = 1800 rpm, torque = 30 N · m, inlet gas temperature: 200 ° C, as follows: Then, the PM oxidation rate and the PM collection rate were measured.

まず、排ガスをバイパス側に捨てながらエンジンを暖気運転した。暖気完了を確認した後、所定条件にダイナモを設定し、排ガス浄化装置へ、電圧値が最大となるまで電圧印加を開始した。次いで排ガスをメイン側(排ガス浄化装置側)へ流し、フルダイリューショントンネルにて5分に1回の割合でPM捕集率を測定した。また、排ガスの一部は粒子数測定装置(ELPI)にて捕集率の経時変化をみるために使用した。こうして実験を30分間行い、排ガスをバイパス側にして終了した。実験終了後のサンプルは分解・粉砕し、HORIBA製のMEXA 1370-PMにてDPFに残ったPM量測定に供試した。捕集率測定値と本分析値からPM酸化速度をもとめた。   First, the engine was warmed up while throwing exhaust gas to the bypass side. After confirming the completion of warm-up, dynamo was set to a predetermined condition, and voltage application was started until the voltage value reached the maximum value to the exhaust gas purification device. Next, exhaust gas was flowed to the main side (exhaust gas purification device side), and the PM collection rate was measured at a rate of once every 5 minutes through a full dilution tunnel. Further, a part of the exhaust gas was used to see the change over time in the collection rate with a particle number measuring device (ELPI). In this way, the experiment was performed for 30 minutes, and the exhaust gas was turned to the bypass side and the experiment was completed. The sample after completion of the experiment was decomposed and pulverized, and was subjected to measurement of the amount of PM remaining in the DPF using MEXA 1370-PM manufactured by HORIBA. The PM oxidation rate was obtained from the collected rate measurement value and the present analysis value.

具体的には、PM酸化速度は
入りPM量−(出PM量+残PM量)
から求め、入りPM量はハニカム構造体に入る排ガスを石英捕集フィルターに通し、その重量増加から求め、出PM量はハニカム構造体から出る排ガスを石英捕集フィルターに通し、その重量増加から求め、残PM量は実験終了後のハニカム構造体を分解し、HORIBA製のMEXA 1370-PMにて測定して求めた。
Specifically, the PM oxidation rate is the amount of incoming PM-(outgoing PM amount + remaining PM amount)
The amount of entering PM is obtained from the increase in the weight of exhaust gas entering the honeycomb structure through the quartz collection filter, and the amount of output PM is obtained from the increase in weight by passing the exhaust gas from the honeycomb structure through the quartz collection filter. The residual PM amount was obtained by disassembling the honeycomb structure after the experiment and measuring it with MEXA 1370-PM manufactured by HORIBA.

NOx浄化率測定試験(R/L繰り返し)
エンジン運転条件:回転数=1800rpm、トルク=60N・m、入りガス温度:300℃にて、以下のようにしてNOx浄化率を測定した。
NOx purification rate measurement test (R / L repetition)
Engine operating conditions: rotational speed = 1800 rpm, torque = 60 N · m, inlet gas temperature: 300 ° C., the NOx purification rate was measured as follows.

まず、排ガスをバイパス側に捨てながらエンジンを暖気運転した。暖気完了を確認した後、所定条件にダイナモを設定し、エンジンECUに軽油を添加できるように条件を指令し、排ガス浄化装置へ、電圧値が最大となるまで電圧印加を開始した。次いで排ガスをメイン側(排ガス浄化装置側)へ流し、HORIBA製のMEXA 9100DのNOx計の分析値から、入りガス中のNOxに対してどれだけNOxを低減できたかを求めた。   First, the engine was warmed up while throwing exhaust gas to the bypass side. After confirming the completion of warm-up, dynamo was set as a predetermined condition, the condition was commanded so that light oil could be added to the engine ECU, and voltage application to the exhaust gas purification device was started until the voltage value reached the maximum. Next, the exhaust gas was flowed to the main side (exhaust gas purification device side), and the amount of NOx reduced with respect to NOx in the incoming gas was determined from the analysis value of the NOX meter of MEXA 9100D made by HORIBA.

以上の結果、棒状電極に放電突起を設けたのみ、又は周囲電極に絶縁部材を設けたのみでは、実験開始から30分間のPM酸化速度はほぼ0g/hLであったが、両者を組み合わせることにより約0.5g/hLまで向上した。   As a result, the PM oxidation rate for 30 minutes from the start of the experiment was almost 0 g / hL only by providing the discharge protrusion on the rod-shaped electrode or by providing the insulating member on the surrounding electrode. It improved to about 0.5 g / hL.

また、同じ体積で、処理ユニットの繰り返しの有無でのPM酸化速度及びNOx浄化率を比較したところ、300℃におけるPM酸化速度は、繰り返し無しで約0.5g/hLであったのに対し、繰り返し有りで0.7g/hLにまで向上し、NOx浄化率は、繰り返し無しで30%であったのに対し、繰り返し有りで35%にまで向上した。   Further, when the PM oxidation rate and NOx purification rate with and without repetition of the processing unit were compared with each other, the PM oxidation rate at 300 ° C. was about 0.5 g / hL without repetition, The NOx purification rate was improved to 0.7 g / hL with repetition, and the NOx purification rate was increased to 35% with repetition while it was 30% without repetition.

また、処理ユニットの繰り返しの有無での絶縁破壊に至る時間を測定し、比較したところ、図7及び8に示すように、処理ユニットを繰り返し構造とすることにより絶縁破壊までの時間が約2倍に向上した。   Moreover, when the time to dielectric breakdown with and without repetition of the processing unit was measured and compared, as shown in FIGS. 7 and 8, the time until dielectric breakdown was approximately doubled by making the processing unit into a repeated structure. Improved.

従来の排ガス浄化装置の一態様を示す断面図である。It is sectional drawing which shows the one aspect | mode of the conventional exhaust gas purification apparatus. 本発明の排ガス浄化装置の一態様を示す断面図である。It is sectional drawing which shows the one aspect | mode of the exhaust gas purification apparatus of this invention. 従来の排ガス浄化装置におけるPM堆積の様子を示す模式図である。It is a schematic diagram which shows the mode of PM deposition in the conventional exhaust gas purification apparatus. マイクロディスチャージの発生を説明する模式図である。It is a schematic diagram explaining generation | occurrence | production of micro discharge. 本発明の排ガス浄化装置の他の態様を示す断面図である。It is sectional drawing which shows the other aspect of the exhaust gas purification apparatus of this invention. 実験装置の構成を示す概略図である。It is the schematic which shows the structure of an experimental apparatus. 処理ユニットの繰り返し無しの場合の絶縁破壊までの時間を示すグラフである。It is a graph which shows the time to the dielectric breakdown when there is no repetition of a processing unit. 処理ユニットの繰り返し有りの場合の絶縁破壊までの時間を示すグラフである。It is a graph which shows the time to the dielectric breakdown in the case with repetition of a processing unit.

符号の説明Explanation of symbols

10、20、50 排ガス浄化装置
11、21、52 ケース
12、22、53 ハニカム構造体
13、23、24 外周電極
14、24、55 棒状電極
15、25 電源
26、57 絶縁部材
27、56 放電突起
10, 20, 50 Exhaust gas purification device 11, 21, 52 Case 12, 22, 53 Honeycomb structure 13, 23, 24 Outer electrode 14, 24, 55 Rod electrode 15, 25 Power source 26, 57 Insulating member 27, 56 Discharge protrusion

Claims (2)

絶縁性ハニカム構造体、
前記ハニカム構造体の外周部に配置された外周電極、及び
前記ハニカム構造体の中心軸上に配置された棒状電極
を有する排ガス浄化装置であって、前記外周電極及び棒状電極が、前記ハニカム構造体の排ガス流れ上流側にまで延在しており、前記棒状電極が、前記ハニカム構造体の排ガス流れ上流側に延在している部位に複数の放電突起を有し、前記外周電極の、前記ハニカム構造体の排気流れ上流側に延在している部位の内周面上に絶縁部材が配置されていることを特徴とする排ガス浄化装置。
Insulating honeycomb structure,
An exhaust gas purification apparatus having an outer peripheral electrode disposed on an outer peripheral portion of the honeycomb structure and a rod-shaped electrode disposed on a central axis of the honeycomb structure, wherein the outer peripheral electrode and the rod-shaped electrode are the honeycomb structure The rod-shaped electrode has a plurality of discharge projections at a portion extending to the exhaust gas flow upstream side of the honeycomb structure, and the honeycomb electrode of the outer peripheral electrode An exhaust gas purification apparatus, wherein an insulating member is disposed on an inner peripheral surface of a portion extending upstream of an exhaust gas flow of a structure.
絶縁性ハニカム構造体、
前記ハニカム構造体の外周部に配置された外周電極、及び
前記ハニカム構造体の中心軸上に配置された棒状電極
を有し、前記外周電極及び棒状電極が、前記ハニカム構造体の排ガス流れ上流側にまで延在しており、前記棒状電極が、前記ハニカム構造体の排ガス流れ上流側に延在している部位に複数の放電突起を有し、前記外周電極の、前記ハニカム構造体の排気流れ上流側に延在している部位の内周面上に絶縁部材が配置されている処理ユニットを、排ガス流れの上流から下流に向かって直列に複数配置することを特徴とする排ガス浄化装置。
Insulating honeycomb structure,
An outer peripheral electrode disposed on an outer peripheral portion of the honeycomb structure; and a rod-shaped electrode disposed on a central axis of the honeycomb structure, wherein the outer peripheral electrode and the rod-shaped electrode are upstream of the exhaust gas flow of the honeycomb structure The rod-shaped electrode has a plurality of discharge protrusions at a portion extending upstream of the exhaust gas flow of the honeycomb structure, and the exhaust gas flow of the honeycomb structure of the outer peripheral electrode An exhaust gas purifying apparatus, wherein a plurality of processing units in which an insulating member is disposed on an inner peripheral surface of a portion extending upstream is disposed in series from upstream to downstream of the exhaust gas flow.
JP2006001678A 2006-01-06 2006-01-06 Exhaust emission control device Pending JP2007182810A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012167614A (en) * 2011-02-15 2012-09-06 Mitsui Eng & Shipbuild Co Ltd Plasma generating device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012167614A (en) * 2011-02-15 2012-09-06 Mitsui Eng & Shipbuild Co Ltd Plasma generating device

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