JP2005106022A - Exhaust emission control device - Google Patents

Exhaust emission control device Download PDF

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JP2005106022A
JP2005106022A JP2003343679A JP2003343679A JP2005106022A JP 2005106022 A JP2005106022 A JP 2005106022A JP 2003343679 A JP2003343679 A JP 2003343679A JP 2003343679 A JP2003343679 A JP 2003343679A JP 2005106022 A JP2005106022 A JP 2005106022A
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honeycomb structure
exhaust gas
electrode
electrodes
mesh electrode
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Kimihisa Tsuji
公壽 辻
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Toyota Motor Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To improve device performance as a whole, by enhancing treating performance in an area for easily performing combustion of particulate matter. <P>SOLUTION: A high carrying area 23 where a carrying quantity of an oxidation catalyst is larger than a carrying quantity in a residual part of a honeycomb structure 20, is arranged in an upstream side end part in the honeycomb structure 20. The device performance can be improved as a whole, by enhancing the treating performance in this area, since the combustion of the particulate matter is easily performed in upstream-downstream side end parts in the honeycomb structure 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、排ガス浄化装置、特にディーゼルエンジンやリーンバーンエンジンの排気系に設けられ、排ガス中に含まれるＰＭ（Particulate Matter,粒子状物質）を捕捉し、燃焼除去して浄化する排ガス浄化装置に関する。   The present invention relates to an exhaust gas purification device, and more particularly to an exhaust gas purification device that is provided in an exhaust system of a diesel engine or a lean burn engine, captures PM (Particulate Matter) contained in the exhaust gas, and burns and removes it. .

大気中の有害物質を除去するための技術として、従来から、相対する一対の電極に交流電圧を印加して発生させたプラズマを用いて排ガスを浄化する排ガス浄化装置（プラズマリアクタ）が提案されている。例えば特許文献１は、電極をなす一対の金網で繊維フィルタを挟み、これらを排ガスの流路中に配置することで排ガスをろ過するようにした装置を開示している。この装置では、繊維フィルタに捕集された排ガス中のＰＭは、両電極間への高電圧の印加により発生されたプラズマのエネルギによりラジカル（フリーラジカル、遊離基）状態にされ、ＨＣはＨ２ＯとＣＯ２に変化し、ＣはＣＯ２に変化するとともに、ＰＭの一部は燃焼して焼却される。しかし、この装置では、供給される排ガスの全量が繊維フィルタを透過するため、排気抵抗が大きくなるという欠点がある。 As a technique for removing harmful substances in the atmosphere, an exhaust gas purification device (plasma reactor) that purifies exhaust gas using plasma generated by applying an alternating voltage to a pair of opposed electrodes has been proposed. Yes. For example, Patent Document 1 discloses an apparatus in which a fiber filter is sandwiched between a pair of metal meshes that form electrodes, and these are arranged in an exhaust gas flow path to filter the exhaust gas. In this apparatus, PM in the exhaust gas collected by the fiber filter is brought into a radical (free radical, free radical) state by the energy of plasma generated by applying a high voltage between both electrodes, and HC is H 2. changes to O and CO 2, C along with changes in the CO 2, a part of the PM is burned by combustion. However, this apparatus has a drawback in that exhaust resistance increases because the entire amount of supplied exhaust gas passes through the fiber filter.

他方、特許文献２のように、上流側の端面から下流側の端面に至る複数の貫通孔を互いに平行に形成した電気絶縁性のハニカム構造体と、その上下流側の端面に配置されたメッシュ電極とを備え、放電プラズマにより排ガス中の有害物質を分解するようにした装置も知られている。この装置は排気抵抗が小さくて済むが、ＰＭが下流側に排出されてしまうという欠点がある。   On the other hand, as in Patent Document 2, an electrically insulating honeycomb structure in which a plurality of through holes extending from an upstream end surface to a downstream end surface are formed in parallel to each other, and a mesh disposed on the upstream and downstream end surfaces There is also known an apparatus that includes an electrode and decomposes harmful substances in exhaust gas by discharge plasma. This device requires only a small exhaust resistance, but has the disadvantage that PM is discharged downstream.

また、特許文献３のように、ハニカム構造体の各貫通孔を、互いに隣り合う貫通孔のうち一方が前端を閉塞され他方が後端を閉塞されるように交互に栓詰し、排ガスが貫通孔の孔壁を透過する際にＰＭがろ過されるようにした装置も提案されている。この装置は特許文献１のものと同様に排気抵抗が大きいという欠点がある。なお、特許文献３の装置ではハニカム構造体の貫通孔内の全表面にわたって、貴金属などの酸化触媒を均等に担持させ、これによって有害物質の反応開始温度を下げ、分解を促進している。   Further, as in Patent Document 3, each through-hole of the honeycomb structure is plugged alternately so that one of the adjacent through-holes closes the front end and the other closes the rear end, and the exhaust gas penetrates. An apparatus has also been proposed in which PM is filtered as it passes through the hole walls. This device has a drawback that the exhaust resistance is large as in the case of Patent Document 1. In the apparatus of Patent Document 3, an oxidation catalyst such as a noble metal is evenly supported over the entire surface in the through-hole of the honeycomb structure, thereby lowering the reaction start temperature of harmful substances and promoting decomposition.

特開２００１−２９５６２９号公報JP 2001-295629 A 特開２００１−２７６５６１号公報JP 2001-276561 A 特公平６−２９５４５号公報Japanese Patent Publication No. 6-29545

ところで出願人は、電気的吸引力によってＰＭをハニカム構造体に吸着させると共に、吸着したＰＭを電極間の放電を利用して分解できる装置を実現すべく、鋭意研究を行っている。出願人が試作したある装置では、貫通孔の上下が開放のハニカム構造体の上流側および下流側の端部の近傍に、メッシュ電極をそれぞれ設け、少なくとも下流側のメッシュ電極がハニカム構造体に接するようにし、これによりハニカム構造体を帯電させ、上流側のメッシュ電極によって逆極性に帯電されたＰＭをハニカム構造体に吸着させると共に、上下流のメッシュ電極間の放電を利用してＰＭを分解することとしている。ここで出願人は、ハニカム構造体の貫通孔内の全表面にわたって酸化触媒を均等に担持させ、かつ、貫通孔内の全表面にＰＭを一様に付着させた状態で、メッシュ電極間にパルス電圧を印加する試験を行ったところ、貫通孔内におけるＰＭの燃焼が、上流側および下流側の端部の近傍で開始されることを知見した。   By the way, the applicant has conducted earnest research in order to realize an apparatus that can adsorb PM to the honeycomb structure by an electric attractive force and decompose the adsorbed PM using discharge between electrodes. In an apparatus manufactured by the applicant, a mesh electrode is provided in the vicinity of the upstream and downstream ends of the honeycomb structure in which the upper and lower through holes are open, and at least the downstream mesh electrode is in contact with the honeycomb structure. Thus, the honeycomb structure is charged, and the PM charged to the reverse polarity by the upstream mesh electrode is adsorbed to the honeycomb structure, and the PM is decomposed using the discharge between the upstream and downstream mesh electrodes. It is going to be. Here, the applicant applies a pulse between the mesh electrodes in a state where the oxidation catalyst is uniformly supported over the entire surface in the through hole of the honeycomb structure and PM is uniformly attached to the entire surface in the through hole. When a test for applying a voltage was performed, it was found that the combustion of PM in the through hole is started in the vicinity of the upstream and downstream ends.

本発明はかかる知見に基づいてなされたものであり、その目的は、ＰＭの燃焼が行われ易い領域における処理性能を高めることで、装置の性能を全体として向上することにある。   The present invention has been made based on such knowledge, and an object of the present invention is to improve the performance of the apparatus as a whole by increasing the processing performance in a region where PM is easily burned.

第１の本発明は、エンジンからの排ガス流路中に配置され、酸化触媒を担持したハニカム構造体と、前記ハニカム構造体の上流側の端部の近傍に設けられた第１の電極と、前記ハニカム構造体の下流側の端部の近傍に設けられた第２の電極と、を備え、前記第１および第２の電極間への電圧の印加により排ガス中の粒子状物質の吸着と分解とを行う排ガス浄化装置であって、前記ハニカム構造体における少なくともいずれかの端部に、前記酸化触媒の担持量が前記ハニカム構造体の残余の部分における担持量より大である高担持領域を設けたことを特徴とする排ガス浄化装置である。   The first aspect of the present invention is a honeycomb structure that is disposed in an exhaust gas flow path from an engine and carries an oxidation catalyst, and a first electrode that is provided in the vicinity of an upstream end of the honeycomb structure, A second electrode provided in the vicinity of the downstream end of the honeycomb structure, and by applying a voltage between the first and second electrodes, adsorption and decomposition of particulate matter in the exhaust gas An exhaust gas purifying apparatus that performs the above-described process, wherein at least one end portion of the honeycomb structure is provided with a high loading region in which the loading amount of the oxidation catalyst is larger than the loading amount in the remaining portion of the honeycomb structure. This is an exhaust gas purification device characterized by the above.

第１の本発明では、ハニカム構造体における少なくともいずれかの端部に、酸化触媒の担持量がハニカム構造体の残余の部分における担持量より大である高担持領域を設けたので、ＰＭの燃焼が行われ易い領域における処理性能を高めることで、装置の性能を全体として向上できる。   In the first aspect of the present invention, at least one end of the honeycomb structure is provided with a high loading region in which the loading amount of the oxidation catalyst is larger than the loading amount in the remaining portion of the honeycomb structure. By improving the processing performance in an area where the process is likely to be performed, the performance of the apparatus as a whole can be improved.

第２の本発明は、前記第１の電極は前記ハニカム構造体から離間しており、且つ前記第２の電極は前記ハニカム構造体に接しており、前記高担持領域は前記ハニカム構造体における上流側の端部に設けられていることを特徴とする請求項１に記載の排ガス浄化装置である。   According to a second aspect of the present invention, the first electrode is separated from the honeycomb structure, the second electrode is in contact with the honeycomb structure, and the highly loaded region is upstream of the honeycomb structure. It is provided in the edge part of the side, It is an exhaust gas purification apparatus of Claim 1 characterized by the above-mentioned.

第２の本発明では、第１の電極がハニカム構造体から離間している一方で、第２の電極がハニカム構造体に接しているため、これら第１および第２の電極間に高電圧を印加すると、第１の電極によって帯電されたＰＭは、ハニカム構造体において第１の電極に対面する位置である上流側の端部に最も良く付着することになる。したがって、この位置に高担持領域を設けることで、第１の本発明の所期の効果を得ることができる。   In the second aspect of the present invention, since the first electrode is separated from the honeycomb structure while the second electrode is in contact with the honeycomb structure, a high voltage is applied between the first and second electrodes. When applied, PM charged by the first electrode adheres best to the upstream end, which is the position facing the first electrode, in the honeycomb structure. Therefore, the desired effect of the first aspect of the present invention can be obtained by providing the high carrying area at this position.

第３の本発明は、前記第１および第２の電極は前記ハニカム構造体に接しており、前記高担持領域は前記ハニカム構造体における下流側の端部に設けられていることを特徴とする請求項１に記載の排ガス浄化装置である。   The third aspect of the present invention is characterized in that the first and second electrodes are in contact with the honeycomb structure, and the high carrying region is provided at an end portion on the downstream side of the honeycomb structure. An exhaust gas purification device according to claim 1.

第３の本発明では、第１および第２の電極がハニカム構造体に接しているため、第１の電極によって帯電されたＰＭは、ハニカム構造体において第２の電極に対面する位置である下流側の端部に最も良く付着することになる。したがって、この位置に高担持領域を設けることで、第１の本発明の所期の効果を得ることができる。   In the third aspect of the present invention, since the first and second electrodes are in contact with the honeycomb structure, PM charged by the first electrode is downstream at the position facing the second electrode in the honeycomb structure. It will adhere best to the side edges. Therefore, the desired effect of the first aspect of the present invention can be obtained by providing the high carrying area at this position.

以下、本発明に係る排ガス浄化装置の実施形態につき、添付図面を参照しつつ詳細に説明する。   Hereinafter, embodiments of an exhaust gas purifying apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

図１は第１実施形態に係る排ガス浄化装置１０の概略構成を示す断面図であり、図２はその内部構成を示す斜視図である。排ガス浄化装置１０は、不図示のエンジン（ディーゼルまたはリーンバーンガソリンエンジン等）の排気系に設けられる。   FIG. 1 is a cross-sectional view showing a schematic configuration of an exhaust gas purification apparatus 10 according to the first embodiment, and FIG. 2 is a perspective view showing an internal configuration thereof. The exhaust gas purification apparatus 10 is provided in an exhaust system of an engine (not shown) (diesel or lean burn gasoline engine or the like).

排ガス浄化装置１０は、両側に截頭円錐状の連結部１２を有するほぼ円筒形の金属製外筒部１４を備え、この外筒部１４に対し、電気絶縁性、耐熱性、緩衝性等を備える支持部材１６、例えばアルミナマットにより支持されたハニカム構造体２０を有している。ハニカム構造体２０は、コーディエライト、シリカ、アルミナ等のセラミックスで形成された多孔質ハニカム構造体である。ハニカム構造体２０の貫通路を除く基材部（壁部）の気孔率は例えば約３０〜４５％とするが、気孔率は任意に選択できる。   The exhaust gas purification apparatus 10 includes a substantially cylindrical metal outer cylinder portion 14 having frustoconical connecting portions 12 on both sides. The outer cylinder portion 14 has electrical insulation, heat resistance, buffering properties, and the like. It has the honeycomb structure 20 supported by the supporting member 16 provided, for example, an alumina mat. The honeycomb structure 20 is a porous honeycomb structure formed of ceramics such as cordierite, silica, and alumina. The porosity of the base material portion (wall portion) excluding the through passage of the honeycomb structure 20 is, for example, about 30 to 45%, but the porosity can be arbitrarily selected.

また、ハニカム構造体２０の上流側端面には、第１の電極としてのメッシュ電極３１、ハニカム構造体２０の下流側端面には、第２の電極としてのメッシュ電極３２が配置されている。   Further, a mesh electrode 31 as a first electrode is disposed on the upstream end face of the honeycomb structure 20, and a mesh electrode 32 as a second electrode is disposed on the downstream end face of the honeycomb structure 20.

メッシュ電極３１は、図２に示すように、複数の電極素子３１ａ、３１ｂが、ハニカム構造体２０の貫通路のピッチとほぼ等しいピッチで互いに平行に配列され、これらが互いに直交するように組み合わされた格子状の電極として構成されている。そして、このメッシュ電極３１は、ハニカム構造体２０の貫通路を規定する壁部の端面に対し回転方向にずらされて存在し、貫通路を跨ぐように配置されている。また、ハニカム構造体２０の下流側端面にもメッシュ電極３１と同様のメッシュ電極の形態で、貫通路を跨ぐようにメッシュ電極３２が配置されている（図２には表されていない）。なお、ここで、メッシュ電極３１，３２の格子のピッチは互いに異なるのが好ましい。このようにすると、メッシュ電極３１，３２間での放電が起こり易く、後述するＰＭの通電燃焼に加えて、排ガスのプラズマ化によるＰＭ燃焼の促進も期待できるからである。   As shown in FIG. 2, in the mesh electrode 31, a plurality of electrode elements 31a and 31b are arranged in parallel to each other at a pitch substantially equal to the pitch of the through-holes of the honeycomb structure 20, and are combined so that they are orthogonal to each other. It is configured as a grid-like electrode. The mesh electrode 31 is shifted in the rotational direction with respect to the end surface of the wall portion defining the through passage of the honeycomb structure 20 and is disposed so as to straddle the through passage. Further, the mesh electrode 32 is disposed on the downstream end face of the honeycomb structure 20 in the form of a mesh electrode similar to the mesh electrode 31 so as to straddle the through path (not shown in FIG. 2). Here, it is preferable that the grid pitches of the mesh electrodes 31 and 32 are different from each other. This is because the discharge between the mesh electrodes 31 and 32 is likely to occur, and in addition to the energization combustion of PM, which will be described later, the promotion of PM combustion due to the plasma conversion of the exhaust gas can be expected.

メッシュ電極３１，３２は、耐腐食性に優れたクロム鋼（例えば、１０Ｃｒ５Ａｌ）で形成できるが、それにのみ限定されるものではなく、他の耐腐食性を有する金属を用いることができる。メッシュ電極３１は、ハニカム構造体２０の上流側端面から所定距離だけ離間して設置されている。メッシュ電極３２は、セラミックボンド等によって、ハニカム構造体２０の下流側端面に貼着されている。なおメッシュ電極３２は、メッシュ電極３１と同様の構造とするほか、導電性の金属ペーストをハニカム構造体２０の下流側端面に塗布することにより形成してもよい。また、メッシュ電極３１，３２はハニカム構造体２０の端面全域を覆う大きさに形成するのが好ましい。   The mesh electrodes 31 and 32 can be formed of chromium steel (for example, 10Cr5Al) having excellent corrosion resistance, but are not limited thereto, and other metals having corrosion resistance can be used. The mesh electrode 31 is installed at a predetermined distance from the upstream end face of the honeycomb structure 20. The mesh electrode 32 is adhered to the downstream end face of the honeycomb structure 20 by ceramic bond or the like. The mesh electrode 32 may have the same structure as the mesh electrode 31 or may be formed by applying a conductive metal paste to the downstream end face of the honeycomb structure 20. The mesh electrodes 31 and 32 are preferably formed in a size that covers the entire end face of the honeycomb structure 20.

メッシュ電極３１は、外筒部１４を貫通して設置されている絶縁碍子１８を通して、直流電源３４の負側に接続され、メッシュ電極３２は同じく絶縁碍子１８を通して直流電源３４の正側に接続されている。なお、この直流電源３４の電圧は５ｋＶ以上、例えば１５〜３０ｋＶ程度が好適である。   The mesh electrode 31 is connected to the negative side of the DC power supply 34 through the insulator 18 installed through the outer cylinder portion 14, and the mesh electrode 32 is connected to the positive side of the DC power supply 34 through the insulator 18. ing. The voltage of the DC power supply 34 is preferably 5 kV or more, for example, about 15 to 30 kV.

図３に示されるように、ハニカム構造体２０の壁部２１には、例えば、Ｐｔ／ＣｅＯ２、Ｍｎ／ＣｅＯ２、Ｆｅ／ＣｅＯ２、Ｎｉ／ＣｅＯ２、Ｃｕ／ＣｅＯ２等の酸化触媒からなる酸化触媒層２２がコーティングにより形成されている。このようにすると、排ガスの活性化によるＰＭの燃焼に加えて、酸化触媒の作用によるＰＭの燃焼が起こり、ＰＭの焼却が促進されることが期待できる。 As shown in FIG. 3, the wall portion 21 of the honeycomb structure 20 is made of an oxidation catalyst such as Pt / CeO 2 , Mn / CeO 2 , Fe / CeO 2 , Ni / CeO 2 , or Cu / CeO 2. The oxidation catalyst layer 22 is formed by coating. If it does in this way, in addition to combustion of PM by activation of exhaust gas, combustion of PM by the action of an oxidation catalyst occurs, and it can be expected that PM incineration is promoted.

そして、ハニカム構造体２０における上流側の端部に、酸化触媒の担持量がハニカム構造体２０の残余の部分における担持量より大である高担持領域２３を設ける。なお、高担持領域２３の軸方向長さＬ１は、使用条件下で予想されるＰＭの付着密度が所定の基準値を上回る領域の軸方向長さとして、ハニカム構造体２０の上流側端部から所定寸法内に実験的に定めてもよく、また高担持領域２３における担持量（例えば、ハニカム構造体２０の単位体積あたりの酸化触媒の重量）が、使用条件下で予想される量のＰＭを燃焼させるのに十分な値となるように実験的に定めてもよい。   Then, a high carrying area 23 in which the carrying amount of the oxidation catalyst is larger than the carrying amount in the remaining part of the honeycomb structure 20 is provided at the upstream end of the honeycomb structure 20. Note that the axial length L1 of the high carrying region 23 is the axial length of the region where the PM adhesion density expected under use conditions exceeds a predetermined reference value, from the upstream end of the honeycomb structure 20. It may be determined experimentally within a predetermined dimension, and the loading amount in the high loading region 23 (for example, the weight of the oxidation catalyst per unit volume of the honeycomb structure 20) is the amount of PM expected under the use conditions. It may be determined experimentally so that the value is sufficient for burning.

この第１実施形態に係る排ガス浄化装置１０においては、エンジンの始動と同時に、電源３４がオンされ、メッシュ電極３１とメッシュ電極３２との間に高電圧が印加される。これによって、メッシュ電極３１からハニカム構造体２０を経てメッシュ電極３２に至る各地点の電位は、メッシュ電極３１の位置を０、ハニカム構造体２０の上流側端部の位置をＰ１，メッシュ電極の位置をＰ２とすると、概ね図４に示されるような分布になると考えられる。この状態で、エンジンから排出されたＰＭを含む排ガスが、排気管を通って排ガス浄化装置１０に導かれると、排ガス中のＰＭがメッシュ電極３１からの放電によってマイナスに帯電され、またハニカム構造体２０がプラスに帯電されるため、ＰＭは電気的吸引力によりハニカム構造体２０に向けて吸引される。この結果、ハニカム構造体２０を流通するＰＭの移動経路が偏向され、ＰＭはそれらの壁部２１の気孔内に堆積されることになるが、図４のようにハニカム構造体２０の上流側端部Ｐ１とメッシュ電極３２の位置Ｐ２との電位差が小さい電位分布においては、ＰＭは、その電位との電位差が大きくなるハニカム構造体２０上の最初の領域、すなわちハニカム構造体２０の上流側の端部近傍を中心として堆積されることになる。   In the exhaust gas purification apparatus 10 according to the first embodiment, the power supply 34 is turned on simultaneously with the start of the engine, and a high voltage is applied between the mesh electrode 31 and the mesh electrode 32. Thus, the potential at each point from the mesh electrode 31 through the honeycomb structure 20 to the mesh electrode 32 is such that the position of the mesh electrode 31 is 0, the position of the upstream end of the honeycomb structure 20 is P1, and the position of the mesh electrode When P2 is P2, it is considered that the distribution is as shown in FIG. In this state, when exhaust gas containing PM discharged from the engine is led to the exhaust gas purification device 10 through the exhaust pipe, PM in the exhaust gas is negatively charged by the discharge from the mesh electrode 31, and the honeycomb structure Since 20 is positively charged, PM is attracted toward the honeycomb structure 20 by an electrical attraction force. As a result, the movement path of the PM flowing through the honeycomb structure 20 is deflected, and PM is deposited in the pores of the wall portions 21, but the upstream end of the honeycomb structure 20 as shown in FIG. In the potential distribution in which the potential difference between the portion P1 and the position P2 of the mesh electrode 32 is small, PM is the first region on the honeycomb structure 20 where the potential difference with the potential is large, that is, the upstream end of the honeycomb structure 20. It is deposited around the vicinity of the part.

そして、この捕集によるＰＭの堆積が進行すると、ＰＭを介してメッシュ電極３１とメッシュ電極３２またはハニカム構造体２０との間に導通路が形成され、アーク放電に近似した通電燃焼がメッシュ電極３１，３２の近傍で起こり、ＰＭが燃焼されて排ガスが浄化される。   Then, when the PM deposition by the collection proceeds, a conduction path is formed between the mesh electrode 31 and the mesh electrode 32 or the honeycomb structure 20 through the PM, and the electric combustion that approximates the arc discharge is performed by the mesh electrode 31. , 32, PM is burned and exhaust gas is purified.

ここで第１実施形態では、ハニカム構造体２０における上流側の端部に、酸化触媒の担持量がハニカム構造体２０の残余の部分における担持量より大である高担持領域２３を設けたので、ＰＭの燃焼が行われ易い領域における処理性能を高めることで、装置の性能を全体として向上することができる。   Here, in the first embodiment, the upstream end portion of the honeycomb structure 20 is provided with the high support area 23 in which the support amount of the oxidation catalyst is larger than the support amount in the remaining portion of the honeycomb structure 20, The performance of the apparatus can be improved as a whole by increasing the processing performance in a region where PM combustion is likely to occur.

また第１実施形態では、ハニカム構造体２０においてメッシュ電極３１に対面する位置である上流側の端部にＰＭが最も良く付着することになるので、この位置に高担持領域２３を設けることで、本発明の所期の効果を得ることができる。   Further, in the first embodiment, PM adheres best to the upstream end that is the position facing the mesh electrode 31 in the honeycomb structure 20, so by providing the high carrying region 23 at this position, The desired effect of the present invention can be obtained.

次に、第２実施形態について説明する。図５は、第２実施形態に係る排ガス浄化装置１１０の概略構成を示す断面図である。本実施形態の排ガス浄化装置１１０は、上記第１実施形態におけるハニカム構造体２０・メッシュ電極３１，３２と同様のハニカム構造体１２０・メッシュ電極１３１，１３２を備えているが、メッシュ電極１３１，１３２が、いずれもハニカム構造体１２０に貼着されている。   Next, a second embodiment will be described. FIG. 5 is a cross-sectional view showing a schematic configuration of the exhaust gas purifying apparatus 110 according to the second embodiment. The exhaust gas purifying apparatus 110 of the present embodiment includes the honeycomb structure 120 and the mesh electrodes 131 and 132 similar to the honeycomb structure 20 and the mesh electrodes 31 and 32 in the first embodiment, but the mesh electrodes 131 and 132 are provided. However, both are adhered to the honeycomb structure 120.

そして、ハニカム構造体１２０における下流側の端部に、酸化触媒の担持量がハニカム構造体１２０の残余の部分における担持量より大である高担持領域１２３を設ける。なお、高担持領域１２３の軸方向長さは、使用条件下で予想されるＰＭの付着密度が所定の基準値を上回る領域の軸方向長さとして、ハニカム構造体２０の下流側端部から所定寸法内に実験的に定めてもよく、また高担持領域１２３における担持量（例えば、ハニカム構造体１２０の単位体積あたりの酸化触媒の重量）が、使用条件下で予想される量のＰＭを燃焼させるのに十分な値となるように実験的に定めてもよい。第２実施形態における残余の構成は、上記第１実施形態と同様であるため、同一符号を付してその詳細な説明は省略する。   Then, at the downstream end portion of the honeycomb structure 120, a high loading region 123 in which the amount of the oxidation catalyst supported is larger than the amount supported in the remaining portion of the honeycomb structure 120 is provided. Note that the axial length of the high-loading region 123 is a predetermined length from the downstream end of the honeycomb structure 20 as the axial length of the region where the PM adhesion density expected under use conditions exceeds a predetermined reference value. It may be determined experimentally within the dimensions, and the loading amount in the high loading region 123 (for example, the weight of the oxidation catalyst per unit volume of the honeycomb structure 120) burns the expected amount of PM under the use conditions. It may be determined experimentally so as to be a value sufficient for the purpose. Since the remaining configuration in the second embodiment is the same as that in the first embodiment, the same reference numerals are assigned and detailed description thereof is omitted.

以上のとおり構成された第２実施形態に係る排ガス浄化装置１１０においては、エンジンの始動と同時に、電源３４がオンされ、メッシュ電極１３１とメッシュ電極１３２との間に高電圧が印加される。これによって、メッシュ電極１３１からハニカム構造体１２０を経てメッシュ電極１３２に至る各地点の電位は、メッシュ電極１３１の位置すなわちハニカム構造体１２０の上流側端部の位置をＰ１１，メッシュ電極１３２の位置をＰ１２とすると、概ね図６に示されるような分布になると考えられる。この状態で、エンジンから排出されたＰＭを含む排ガスが、排気管を通って排ガス浄化装置１１０に導かれると、排ガス中のＰＭがメッシュ電極１３１からの放電によってマイナスに帯電され、またハニカム構造体１２０がプラスに帯電されるため、ＰＭは電気的吸引力によりハニカム構造体１２０に向けて吸引される。   In the exhaust gas purification apparatus 110 according to the second embodiment configured as described above, the power supply 34 is turned on simultaneously with the start of the engine, and a high voltage is applied between the mesh electrode 131 and the mesh electrode 132. As a result, the potential at each point from the mesh electrode 131 through the honeycomb structure 120 to the mesh electrode 132 is P11, the position of the upstream end of the honeycomb structure 120, that is, the position of the mesh electrode 132. Assuming P12, the distribution is generally as shown in FIG. In this state, when the exhaust gas containing PM discharged from the engine is led to the exhaust gas purification device 110 through the exhaust pipe, the PM in the exhaust gas is negatively charged by the discharge from the mesh electrode 131, and the honeycomb structure. Since 120 is charged positively, PM is attracted toward the honeycomb structure 120 by an electrical attraction force.

この結果、ハニカム構造体１２０を流通するＰＭの移動経路が偏向され、ＰＭはそれらの壁部２１の気孔内に堆積されることになるが、図６のようにハニカム構造体１２０の上流側端部Ｐ１とメッシュ電極１３２の位置Ｐ２との電位差が大きく且つ概ね線形に推移する電位分布においては、ＰＭは、その電位との電位差が最大となるハニカム構造体１２０上の領域、すなわちハニカム構造体１２０の下流側の端部近傍を中心として堆積されることになると考えられる。   As a result, the movement path of the PM flowing through the honeycomb structure 120 is deflected, and PM is deposited in the pores of the wall portions 21, but the upstream end of the honeycomb structure 120 as shown in FIG. In the potential distribution in which the potential difference between the portion P1 and the position P2 of the mesh electrode 132 is large and changes substantially linearly, PM is a region on the honeycomb structure 120 where the potential difference from the potential is maximum, that is, the honeycomb structure 120. It is thought that it will be deposited centering on the vicinity of the downstream end portion.

そして、この捕集によるＰＭの堆積が進行すると、ＰＭを介してメッシュ電極１３１とメッシュ電極１３２またはハニカム構造体１２０との間に導通路が形成され、アーク放電に近似した通電燃焼がメッシュ電極１３１，１３２の近傍で起こり、ＰＭが燃焼されて排ガスが浄化される。   Then, when the PM deposition by the collection proceeds, a conduction path is formed between the mesh electrode 131 and the mesh electrode 132 or the honeycomb structure 120 via the PM, and the electric combustion that approximates arc discharge is performed by the mesh electrode 131. , 132, PM is combusted and exhaust gas is purified.

ここで第２実施形態では、ハニカム構造体１２０における下流側の端部に、酸化触媒の担持量がハニカム構造体１２０の残余の部分における担持量より大である高担持領域１２３を設けたので、ＰＭの燃焼が行われ易い領域における処理性能を高めることで、装置の性能を全体として向上することができる。   Here, in the second embodiment, since the supporting amount of the oxidation catalyst is larger than the supporting amount in the remaining part of the honeycomb structure 120 at the downstream end of the honeycomb structure 120, the high supporting region 123 is provided. The performance of the apparatus can be improved as a whole by increasing the processing performance in a region where PM combustion is likely to occur.

また第２実施形態では、ハニカム構造体１２０においてメッシュ電極１３２に対面する位置である下流側の端部に最も良く付着することになると考えられるので、この位置に高担持領域１２３を設けることで、本発明の所期の効果を得ることができる。   Further, in the second embodiment, it is considered that the honeycomb structure 120 adheres best to the downstream end that is the position facing the mesh electrode 132, so by providing the high carrying region 123 at this position, The desired effect of the present invention can be obtained.

なお、上記各実施形態ではハニカム構造体２０，１２０の壁部２１の端面から表面にわたって高担持領域２３，１２３を形成したが、本発明における高担持領域はハニカム構造体の端面のみに形成されていてもよい。また本発明では高担持領域以外のハニカム構造体の部位は、触媒物質を担持していなくてもよい。さらに、上記各実施形態ではハニカム構造体への触媒物質のコーティングの厚さを変えることで高担持領域２３，１２３を実現したが、本発明における高担持領域は、触媒物質の担持量（例えば、ハニカム構造体の単位体積あたりの触媒物質の重量）が大となるような方法であれば、他の方法、例えばハニカム構造体における所定領域について気孔率を他の領域に比して高くする等の方法によって実現してもよく、かかる構成も本発明の範疇に属するものである。   In each of the above embodiments, the high supporting regions 23 and 123 are formed from the end surface of the wall portion 21 of the honeycomb structure 20 or 120 to the surface. However, the high supporting region in the present invention is formed only on the end surface of the honeycomb structure. May be. Further, in the present invention, the portion of the honeycomb structure other than the high supporting region may not support the catalyst material. Further, in each of the above embodiments, the high loading regions 23 and 123 are realized by changing the thickness of the coating of the catalyst material on the honeycomb structure. However, the high loading region in the present invention is the amount of the catalyst material loaded (for example, If the method is such that the weight of the catalyst material per unit volume of the honeycomb structure is large, other methods such as increasing the porosity of the predetermined region in the honeycomb structure compared to other regions, etc. It may be realized by a method, and such a configuration also belongs to the category of the present invention.

また、上記各実施形態においては、上流側のメッシュ電極３１，１３１を負極に、下流側のメッシュ電極３２，１３２を正極に接続する例につき説明したが、これらは、両者間に所定の高電圧が印加される形態であれば足り、逆の極性であってもよく、またいずれか一方を接地させてもよい。また、その電源の形態は、直流のみならず、パルス電源や交流電源であってもよい。さらに、それらの電圧印加の形態も上述の常時印加に限られず、ＰＭの捕集要求や燃焼処理要求の必要性に応じて、所望の時期に行うようにしてもよい。また、上記各実施形態では全ての電極をメッシュ電極とした例について説明したが、本発明ではそれ以外の構造の電極、例えば棒状電極や筒状電極を用いてもよい。   In each of the above embodiments, the example has been described in which the upstream mesh electrodes 31 and 131 are connected to the negative electrode, and the downstream mesh electrodes 32 and 132 are connected to the positive electrode. As long as the voltage is applied, the polarity may be reversed, or one of them may be grounded. Further, the form of the power supply is not limited to DC, but may be a pulse power supply or an AC power supply. Further, the mode of voltage application is not limited to the above-described constant application, but may be performed at a desired time according to the necessity of PM collection request or combustion processing request. In each of the above embodiments, an example in which all the electrodes are mesh electrodes has been described. However, in the present invention, electrodes having other structures, for example, rod-shaped electrodes and cylindrical electrodes may be used.

本発明の第１実施形態の排ガス浄化装置を示す断面図である。It is sectional drawing which shows the exhaust gas purification apparatus of 1st Embodiment of this invention. 第１実施形態の排ガス浄化装置の内部構成を示す斜視図である。It is a perspective view which shows the internal structure of the exhaust gas purification apparatus of 1st Embodiment. 第１実施形態におけるハニカム構造体の要部を示す断面図である。It is sectional drawing which shows the principal part of the honeycomb structure in 1st Embodiment. 第１実施形態における電位分布の概略を示すグラフである。It is a graph which shows the outline of the electric potential distribution in 1st Embodiment. 本発明の第２実施形態の排ガス浄化装置を示す断面図である。It is sectional drawing which shows the exhaust gas purification apparatus of 2nd Embodiment of this invention. 第２実施形態における電位分布の概略を示すグラフである。It is a graph which shows the outline of the electric potential distribution in 2nd Embodiment.

符号の説明Explanation of symbols

１０，１１０ 排ガス浄化装置
２０，１２０ ハニカム構造体
２３，１２３ 高担持領域
３１，３２，１３１，１３２ メッシュ電極
３４ 電源
10, 110 Exhaust gas purification device 20, 120 Honeycomb structure 23, 123 High carrying area 31, 32, 131, 132 Mesh electrode 34 Power supply

Claims (3)

エンジンからの排ガス流路中に配置され、酸化触媒を担持したハニカム構造体と、
前記ハニカム構造体の上流側の端部の近傍に設けられた第１の電極と、
前記ハニカム構造体の下流側の端部の近傍に設けられた第２の電極と、
を備え、前記第１および第２の電極間への電圧の印加により排ガス中の粒子状物質の吸着と分解とを行う排ガス浄化装置であって、
前記ハニカム構造体における少なくともいずれかの端部に、前記酸化触媒の担持量が前記ハニカム構造体の残余の部分における担持量より大である高担持領域を設けたことを特徴とする排ガス浄化装置。 A honeycomb structure disposed in an exhaust gas flow path from the engine and carrying an oxidation catalyst;
A first electrode provided in the vicinity of the upstream end of the honeycomb structure;
A second electrode provided in the vicinity of the downstream end of the honeycomb structure;
An exhaust gas purification apparatus that performs adsorption and decomposition of particulate matter in exhaust gas by applying a voltage between the first and second electrodes,
An exhaust gas purifying apparatus, characterized in that at least one end of the honeycomb structure is provided with a high support area in which the support amount of the oxidation catalyst is larger than the support amount in the remaining part of the honeycomb structure. 前記第１の電極は前記ハニカム構造体から離間しており、且つ前記第２の電極は前記ハニカム構造体に接しており、
前記高担持領域は前記ハニカム構造体における上流側の端部に設けられていることを特徴とする請求項１に記載の排ガス浄化装置。 The first electrode is spaced from the honeycomb structure, and the second electrode is in contact with the honeycomb structure;
The exhaust gas purification apparatus according to claim 1, wherein the high carrying region is provided at an upstream end of the honeycomb structure. 前記第１および第２の電極は前記ハニカム構造体に接しており、
前記高担持領域は前記ハニカム構造体における下流側の端部に設けられていることを特徴とする請求項１に記載の排ガス浄化装置。

The first and second electrodes are in contact with the honeycomb structure;
The exhaust gas purification device according to claim 1, wherein the high carrying region is provided at an end portion on the downstream side of the honeycomb structure.

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JP2010532836A (en) * 2007-07-02 2010-10-14 カミンズ フィルトレイション アイピー インク． Prevention of clogging of the aftertreatment device in the exhaust system
WO2010134448A1 (en) * 2009-05-19 2010-11-25 国立大学法人宇都宮大学 Device and method for combusting particulate substances
US7946111B2 (en) * 2005-05-18 2011-05-24 Toyota Jidosha Kabushiki Kaisha Apparatus and method for PM purification
JP2016123890A (en) * 2014-12-26 2016-07-11 日産自動車株式会社 Honeycomb type monolith catalyst, and production method thereof
KR102472601B1 (en) * 2022-09-30 2022-11-30 주식회사 스마트파워 DPF device for generators with improved particulate matter reduction performance

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7946111B2 (en) * 2005-05-18 2011-05-24 Toyota Jidosha Kabushiki Kaisha Apparatus and method for PM purification
JP2009523209A (en) * 2006-01-13 2009-06-18 エミテック ゲゼルシヤフト フユア エミツシオンス テクノロギー ミツト ベシユレンクテル ハフツング Method and apparatus for reducing the amount of particles in the exhaust gas of an internal combustion engine
JP2010532836A (en) * 2007-07-02 2010-10-14 カミンズ フィルトレイション アイピー インク． Prevention of clogging of the aftertreatment device in the exhaust system
US8691724B2 (en) 2007-07-02 2014-04-08 Cummins Filtration Ip, Inc. Prevention of face-plugging on aftertreatment devices in exhaust
WO2010134448A1 (en) * 2009-05-19 2010-11-25 国立大学法人宇都宮大学 Device and method for combusting particulate substances
JP5572156B2 (en) * 2009-05-19 2014-08-13 国立大学法人宇都宮大学 Particulate matter combustion apparatus and method
US8966881B2 (en) 2009-05-19 2015-03-03 Utsunomiya University Device and method for combusting particulate substances
JP2016123890A (en) * 2014-12-26 2016-07-11 日産自動車株式会社 Honeycomb type monolith catalyst, and production method thereof
KR102472601B1 (en) * 2022-09-30 2022-11-30 주식회사 스마트파워 DPF device for generators with improved particulate matter reduction performance

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