JP4332847B2 - Exhaust gas purification device - Google Patents

Exhaust gas purification device Download PDF

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JP4332847B2
JP4332847B2 JP2003359799A JP2003359799A JP4332847B2 JP 4332847 B2 JP4332847 B2 JP 4332847B2 JP 2003359799 A JP2003359799 A JP 2003359799A JP 2003359799 A JP2003359799 A JP 2003359799A JP 4332847 B2 JP4332847 B2 JP 4332847B2
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exhaust gas
honeycomb structure
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outer peripheral
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JP2005120987A (en
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大 垣花
勇 中田
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Toyota Motor Corp
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Description

本発明は、プラズマを用いて排気ガスを浄化する排ガス浄化装置に関する。   The present invention relates to an exhaust gas purification apparatus that purifies exhaust gas using plasma.

従来から、車両用内燃機関の排気系統に組み込まれて当該内燃機関の排気ガスを浄化する装置として、相対する電極に高電圧を印加して発生させたプラズマを用いて排気ガスを浄化する排ガス浄化装置（プラズマリアクタ）が知られている（例えば、特許文献１参照。）。この排ガス浄化装置は、いわゆるウォールフロー型の浄化装置として構成されており、排気系統に組み込まれるケーシング（浄化容器）と、排気ガス中のパティキュレート物質（以下、「ＰＭ物質」という）を捕集するセラミック製フィルタとを有している。フィルタは、ケーシングの内部に配置され、その外周部に上流側排気ガス通路を画成すると共に、その中心部に下流側排気ガス通路を画成する。   Conventionally, as an apparatus for purifying exhaust gas of an internal combustion engine incorporated in an exhaust system of a vehicle internal combustion engine, exhaust gas purification that purifies exhaust gas using plasma generated by applying a high voltage to the opposite electrode An apparatus (plasma reactor) is known (for example, refer to Patent Document 1). This exhaust gas purification device is configured as a so-called wall flow type purification device, and collects a casing (purification container) incorporated in an exhaust system and particulate matter (hereinafter referred to as “PM material”) in exhaust gas. And a ceramic filter. The filter is disposed inside the casing, and defines an upstream exhaust gas passage in the outer peripheral portion thereof, and defines a downstream exhaust gas passage in the central portion thereof.

この排ガス浄化装置のケーシング内に導入された排気ガスは、ケーシングの内周面付近の上流側排ガス通路に流れ込み、セラミック製フィルタの襞状に折り曲げられた部分を流通した後、下流側排気ガス通路を介してケーシングから流出する。そして、排気ガスがセラミック製フィルタを流通する間に、排気ガス中のＰＭ物質がフィルタにより捕集される。更に、フィルタによって捕集されたＰＭ物質は、プラズマによって反応消滅または焼却される。   The exhaust gas introduced into the casing of the exhaust gas purification apparatus flows into the upstream exhaust gas passage near the inner peripheral surface of the casing, and after flowing through the bent portion of the ceramic filter, the downstream exhaust gas passage Flows out of the casing through. And while exhaust gas distribute | circulates a ceramic filter, PM substance in exhaust gas is collected by a filter. Further, the PM material collected by the filter is extinguished or incinerated by the plasma.

特開２００１−２９５６２９号公報JP 2001-295629 A

ここで、上述のようなウォールフロー型の排ガス浄化装置では、フィルタ（ケーシング）の入口と出口との間における圧力差（背圧）が大きくなってしまいがちである。このため、ウォールフロー型の排ガス浄化装置を用いた場合、排ガス浄化装置の適用対象である内燃機関等の出力低下を招いてしまうおそれがある。   Here, in the above-described wall flow type exhaust gas purification apparatus, the pressure difference (back pressure) between the inlet and the outlet of the filter (casing) tends to increase. For this reason, when a wall flow type exhaust gas purifying apparatus is used, there is a possibility that the output of an internal combustion engine or the like to which the exhaust gas purifying apparatus is applied is reduced.

これに対して、排ガス浄化に伴う内燃機関等の出力低下を防止するためには、浄化容器内の排気ガスの流れが一方向に保たれるストレートフロー型の排ガス浄化装置を用いることが考えられる。しかしながら、セラミックハニカム材等からなるフィルタを備えたストレートフロー型の排ガス浄化装置では、ガス流路の中心部を通過する排気ガスの流速および流量が増加する傾向にあり、フィルタ中心部で目詰まりが生じることにより、ＰＭ物質の捕集効率や処理効率が低下し、また背圧が更に上昇してしまうことがある。   On the other hand, in order to prevent output reduction of the internal combustion engine or the like accompanying exhaust gas purification, it is conceivable to use a straight flow type exhaust gas purification device in which the flow of exhaust gas in the purification container is maintained in one direction. . However, in a straight flow type exhaust gas purification apparatus equipped with a filter made of a ceramic honeycomb material or the like, the flow rate and flow rate of the exhaust gas passing through the central part of the gas flow path tend to increase, and clogging occurs in the central part of the filter. As a result, the collection efficiency and processing efficiency of the PM substance may decrease, and the back pressure may further increase.

そこで、本発明は、効率よくパティキュレート物質を捕集・処理可能な排ガス浄化装置の提供を目的とする。   Accordingly, an object of the present invention is to provide an exhaust gas purifying apparatus capable of efficiently collecting and processing particulate matter.

本発明による排ガス浄化装置は、プラズマを用いて排気ガスを浄化する排ガス浄化装置において、排気ガスが導入される浄化容器と、浄化容器内に配置されたハニカム構造体と、ハニカム構造体の中心に配置され、排気ガスの流れ方向に延びる中心電極と、ハニカム構造体の外周に配置された外周電極とを備え、ハニカム構造体は、中心から外周に向かうにつれてセル密度が漸減している領域を含んでいることを特徴とする。   An exhaust gas purifying apparatus according to the present invention is an exhaust gas purifying apparatus that purifies exhaust gas using plasma, a purification container into which exhaust gas is introduced, a honeycomb structure disposed in the purification container, and a center of the honeycomb structure. A central electrode extending in the exhaust gas flow direction and an outer peripheral electrode disposed on the outer periphery of the honeycomb structure, the honeycomb structure including a region where the cell density gradually decreases from the center toward the outer periphery. It is characterized by being.

この排ガス浄化装置は、中心電極等に対して高電圧を印加して発生させたプラズマを用いて排気ガスを浄化するものであり、浄化容器内で排気ガス中のＰＭ物質を捕集するためのハニカム構造体を有する。そして、この排ガス浄化装置のハニカム構造体は、中心から外周に向かうにつれてセル密度が漸減している領域を含んでいる。これにより、ハニカム構造体の中心部における抵抗が増加するので、ハニカム構造体のセル密度が低い外周側の領域における排気ガスの流量を増加させることができる。従って、この排ガス浄化装置では、ハニカム構造体の中心部における目詰まりが抑制されると共に、ハニカム構造体におけるＰＭ物質の分布が全体に均一化されることになり、ハニカム構造体の全体で均一かつ効率よくＰＭ物質を捕集・処理することが可能となる。   This exhaust gas purification device purifies exhaust gas using plasma generated by applying a high voltage to the center electrode and the like, and collects PM substances in the exhaust gas in the purification container. It has a honeycomb structure. The honeycomb structure of the exhaust gas purifying apparatus includes a region where the cell density gradually decreases from the center toward the outer periphery. As a result, the resistance in the central portion of the honeycomb structure increases, so that the exhaust gas flow rate in the outer peripheral region where the cell density of the honeycomb structure is low can be increased. Therefore, in this exhaust gas purification device, clogging at the center of the honeycomb structure is suppressed, and the distribution of the PM substance in the honeycomb structure is made uniform throughout. It becomes possible to collect and process PM substances efficiently.

また、中心電極と外周電極との間に配置された複数の筒状電極を更に備え、複数の筒状電極には、中心電極と対をなす電極と、外周電極と対をなす電極とが含まれていると好ましい。   Further, a plurality of cylindrical electrodes arranged between the center electrode and the outer peripheral electrode are further provided, and the plurality of cylindrical electrodes include an electrode paired with the central electrode and an electrode paired with the outer peripheral electrode. It is preferable.

このような構成を採用すれば、互いに対をなす電極間におけるＰＭ物質の捕集効率および処理効率をより一層を向上させることが可能となる。   By adopting such a configuration, it becomes possible to further improve the collection efficiency and the processing efficiency of the PM substance between the electrodes paired with each other.

この場合、中心電極を含む一対の電極間に配置された内側ハニカム構造体と、外周電極を含む一対の電極間に配置されており、内側ハニカム構造体よりも低いセル密度を有する外側ハニカム構造体とを更に備えると好ましい。   In this case, the inner honeycomb structure disposed between the pair of electrodes including the center electrode and the outer honeycomb structure disposed between the pair of electrodes including the outer peripheral electrode and having a lower cell density than the inner honeycomb structure. Are preferably included.

また、内側ハニカム構造体と外側ハニカム構造体との間で流体の流通が実質的に規制されていると好ましい。   Further, it is preferable that the fluid flow is substantially regulated between the inner honeycomb structure and the outer honeycomb structure.

このような構成を採用すれば、浄化容器の入口と出口との間における圧力差（背圧）が大きくなってしまうことを確実に防止することができる。   By adopting such a configuration, it is possible to reliably prevent a pressure difference (back pressure) between the inlet and the outlet of the purification container from increasing.

本発明によれば、効率よくパティキュレート物質を捕集・処理可能な排ガス浄化装置の実現が可能となる。   According to the present invention, it is possible to realize an exhaust gas purifying apparatus capable of efficiently collecting and processing particulate matter.

以下、図面と共に本発明による排ガス浄化装置の好適な実施形態について詳細に説明する。   Hereinafter, preferred embodiments of an exhaust gas purifying apparatus according to the present invention will be described in detail with reference to the drawings.

図１は、本発明による排ガス浄化装置を示す断面図であり、図２は、図１におけるII−II線についての断面図である。これらの図面に示される排ガス浄化装置１は、車両に適用されると好適なものであり、図示されない内燃機関の燃焼室から排出される排気ガスを浄化するために、当該内燃機関の排気系統を構成する排気管Ｌ１と排気管Ｌ２との間に組み込まれる。図１および図２に示されるように、排ガス浄化装置１は、浄化容器２を有し、この浄化容器２の内部には、排気管Ｌ１を介して内燃機関の燃焼室から排出される排気ガスが導入される。そして、浄化容器２の内部で浄化された排気ガスは、排気管Ｌ２を介して外部に排出される。   FIG. 1 is a cross-sectional view showing an exhaust gas purifying apparatus according to the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. The exhaust gas purification apparatus 1 shown in these drawings is suitable when applied to a vehicle. In order to purify exhaust gas discharged from a combustion chamber of an internal combustion engine (not shown), an exhaust system of the internal combustion engine is used. It is incorporated between the exhaust pipe L1 and the exhaust pipe L2. As shown in FIGS. 1 and 2, the exhaust gas purification apparatus 1 has a purification container 2, and the exhaust gas discharged from the combustion chamber of the internal combustion engine through the exhaust pipe L <b> 1 is inside the purification container 2. Is introduced. Then, the exhaust gas purified inside the purification container 2 is discharged to the outside through the exhaust pipe L2.

浄化容器２は、金属等により概ね円筒状に形成されており、排気管Ｌ１またはＬ２に接続される入口端部２１および出口端部２２と、排気管Ｌ１，Ｌ２よりも大きな内径を有する拡径部２３と、入口端部２１と拡径部２３との間および出口端部２２と拡径部２３との間に形成されたコーン部２４とを含む。また、浄化容器２の拡径部２３の内周面には、円筒状に形成された絶縁部材３が固定されており、絶縁部材３の内周面には、金属メッシュあるいは金属ペースト等により円筒状に形成された外周電極４が積層されている。   The purification container 2 is formed in a substantially cylindrical shape with metal or the like, and has an inlet end portion 21 and an outlet end portion 22 connected to the exhaust pipe L1 or L2, and an expanded diameter having a larger inner diameter than the exhaust pipes L1 and L2. And a cone portion 24 formed between the inlet end portion 21 and the enlarged diameter portion 23 and between the outlet end portion 22 and the enlarged diameter portion 23. Further, an insulating member 3 formed in a cylindrical shape is fixed to the inner peripheral surface of the enlarged diameter portion 23 of the purification container 2, and the inner peripheral surface of the insulating member 3 is cylindrical with a metal mesh or a metal paste or the like. The outer peripheral electrodes 4 formed in a shape are stacked.

外周電極４の内周面には、浄化容器２の内部に流れ込んだ排気ガス中のＰＭ物質を捕集するための外側ハニカム構造体５が固定されている。外側ハニカム構造体５は、セラミック（例えば、コージェライトやアルミナ）等により円筒状に形成されており、排気ガスの流通方向（浄化容器２の延在方向）に延びる多数のセルを有している。また、外側ハニカム構造体５には、例えば、Ｐｔ／ＣｅＯ２，Ｍｎ／ＣｅＯ２，Ｆｅ／ＣｅＯ２，Ｎｉ／ＣｅＯ２，Ｃｕ／ＣｅＯ２等の酸化触媒が担持されている。更に、外側ハニカム構造体５の内周面には、金属メッシュあるいは金属ペースト等により円筒状に形成された電極６が積層されている。この電極６は、外側ハニカム構造体５を介して外周電極４と対をなす。 An outer honeycomb structure 5 for collecting PM substances in the exhaust gas flowing into the purification container 2 is fixed to the inner peripheral surface of the outer peripheral electrode 4. The outer honeycomb structure 5 is formed in a cylindrical shape from ceramic (for example, cordierite or alumina) and has a number of cells extending in the exhaust gas flow direction (extension direction of the purification container 2). . The outer honeycomb structure 5 carries an oxidation catalyst such as Pt / CeO 2 , Mn / CeO 2 , Fe / CeO 2 , Ni / CeO 2 , and Cu / CeO 2 . Further, an electrode 6 formed in a cylindrical shape by a metal mesh or a metal paste is laminated on the inner peripheral surface of the outer honeycomb structure 5. The electrode 6 is paired with the outer peripheral electrode 4 through the outer honeycomb structure 5.

電極６の内周面には、円筒状に形成された絶縁部材７が固定されており、絶縁部材７の内周面には、金属メッシュあるいは金属ペースト等により円筒状に形成された電極８が積層されている。そして、電極８の内周面にも、浄化容器２の内部に流れ込んだ排気ガス中のＰＭ物質を捕集するための内側ハニカム構造体９が固定されている。なお、外側ハニカム構造体５と内側ハニカム構造体９との間では、排気ガスの流通が絶縁部材７によって実質的に規制される。これにより、浄化容器２の入口と出口との間における圧力差（背圧）が大きくなってしまうことが確実に防止される。   An insulating member 7 formed in a cylindrical shape is fixed to the inner peripheral surface of the electrode 6, and an electrode 8 formed in a cylindrical shape by a metal mesh or a metal paste is provided on the inner peripheral surface of the insulating member 7. Are stacked. An inner honeycomb structure 9 for collecting PM substances in the exhaust gas flowing into the purification container 2 is also fixed to the inner peripheral surface of the electrode 8. Note that between the outer honeycomb structure 5 and the inner honeycomb structure 9, the flow of exhaust gas is substantially restricted by the insulating member 7. This reliably prevents the pressure difference (back pressure) between the inlet and the outlet of the purification container 2 from increasing.

内側ハニカム構造体９も、外側ハニカム構造体５と同様に、セラミック（例えば、コージェライトやアルミナ）等からなるハニカム材により概ね円筒状に形成されており、排気ガスの流通方向（浄化容器２の延在方向）に延びる多数のセルを有している。そして、本実施形態において、内側ハニカム構造体９は、外側ハニカム構造体５よりも高いセル密度を有するように形成されている。また、内側ハニカム構造体９にも、例えば、Ｐｔ／ＣｅＯ２，Ｍｎ／ＣｅＯ２，Ｆｅ／ＣｅＯ２，Ｎｉ／ＣｅＯ２，Ｃｕ／ＣｅＯ２等の酸化触媒が担持されている。 Similarly to the outer honeycomb structure 5, the inner honeycomb structure 9 is also formed in a substantially cylindrical shape by a honeycomb material made of ceramic (for example, cordierite or alumina), and the exhaust gas flow direction (the purification container 2 It has a large number of cells extending in the extending direction). In the present embodiment, the inner honeycomb structure 9 is formed to have a higher cell density than the outer honeycomb structure 5. The inner honeycomb structure 9 also carries an oxidation catalyst such as Pt / CeO 2 , Mn / CeO 2 , Fe / CeO 2 , Ni / CeO 2 , and Cu / CeO 2 .

更に、浄化容器２の内部には、内側ハニカム構造体９の中心を貫通すると共に排気ガスの流れ方向に延在するように棒状の中心電極１０が配置されている。この中心電極１０は、内側ハニカム構造体９を介して電極８と対をなす。また、中心電極１０の先端部は、排気ガスの入口（排気管Ｌ１）に向けて内側ハニカム構造体９から突出しており、当該先端部からは、複数本の棘状の放電突起１０ｄが放射状に延出されている。   Further, a rod-shaped center electrode 10 is disposed inside the purification container 2 so as to penetrate the center of the inner honeycomb structure 9 and extend in the exhaust gas flow direction. The center electrode 10 is paired with the electrode 8 through the inner honeycomb structure 9. Further, the distal end portion of the center electrode 10 protrudes from the inner honeycomb structure 9 toward the exhaust gas inlet (exhaust pipe L1), and a plurality of spine-shaped discharge protrusions 10d radiate from the distal end portion. It has been extended.

図１に示されるように、浄化容器２の内部に配置されている電極６と中心電極１０とには、図示されない給電端子等を介して高圧電源１１が接続され、電極６と対をなす外周電極４および中心電極１０と対をなす電極８は接地されている。本実施形態では、電極６および中心電極１０を負極として外周電極４と電極６との間および電極８と中心電極１０との間に高電圧が印加される。なお、高圧電源１１としては、直流高圧電源、交流高圧電源および直流パルス電源の何れかを用いることができる。   As shown in FIG. 1, a high voltage power source 11 is connected to the electrode 6 and the center electrode 10 disposed inside the purification container 2 via a power supply terminal (not shown), and the outer periphery forming a pair with the electrode 6. The electrode 8 paired with the electrode 4 and the center electrode 10 is grounded. In the present embodiment, the electrode 6 and the center electrode 10 are used as negative electrodes, and a high voltage is applied between the outer peripheral electrode 4 and the electrode 6 and between the electrode 8 and the center electrode 10. As the high-voltage power supply 11, any one of a DC high-voltage power supply, an AC high-voltage power supply, and a DC pulse power supply can be used.

さて、上述のように構成される排ガス浄化装置１では、内燃機関の始動と共に、排気管Ｌ１を介して内燃機関の燃焼室からの排気ガスが浄化容器２の内部に導入される。また、内燃機関の始動に合わせて、互いに対をなす外周電極４と電極６との間（外側ハニカム構造体５）および互いに対をなす電極８と中心電極１０との間（内側ハニカム構造体９）にプラズマを発生させるべく、外周電極４と電極６との間および電極８と中心電極１０との間に高圧電源１１によって高電圧が印加される。   In the exhaust gas purification apparatus 1 configured as described above, exhaust gas from the combustion chamber of the internal combustion engine is introduced into the purification container 2 through the exhaust pipe L1 when the internal combustion engine is started. Further, in accordance with the start of the internal combustion engine, a pair between the outer peripheral electrode 4 and the electrode 6 (outer honeycomb structure 5) and a pair of the electrode 8 and the center electrode 10 (inner honeycomb structure 9). In order to generate plasma, a high voltage is applied between the outer peripheral electrode 4 and the electrode 6 and between the electrode 8 and the center electrode 10 by the high-voltage power supply 11.

ここで、浄化容器２内の外側ハニカム構造体５と内側ハニカム構造体とを一体のハニカム構造体９とみなした場合、当該一体のハニカム構造体では、中心から外周に向かうにつれてセル密度が漸減することになる。これにより、排ガス浄化装置１では、一体のハニカム構造体の中心部、すなわち、内側ハニカム構造体９に流入しようとする排気ガスに対する抵抗が増加することになる。従って、排ガス浄化装置１では、排気ガスを入口側のコーン部２４の内部で拡散させて、セル密度が低い外側ハニカム構造体５における排気ガスの流量を増加させることが可能となる。この結果、ガス流路の中心部に位置する内側ハニカム構造体９の目詰まりが抑制されると共に、外側ハニカム構造体５と内側ハニカム構造体９とにおけるＰＭ物質の分布が全体に均一化される。   Here, when the outer honeycomb structure 5 and the inner honeycomb structure in the purification container 2 are regarded as an integrated honeycomb structure 9, in the integrated honeycomb structure, the cell density gradually decreases from the center toward the outer periphery. It will be. As a result, in the exhaust gas purification device 1, the resistance to the exhaust gas that is about to flow into the central portion of the integral honeycomb structure, that is, the inner honeycomb structure 9, is increased. Therefore, in the exhaust gas purifying apparatus 1, it is possible to increase the flow rate of the exhaust gas in the outer honeycomb structure 5 having a low cell density by diffusing the exhaust gas inside the cone portion 24 on the inlet side. As a result, clogging of the inner honeycomb structure 9 located at the center of the gas flow path is suppressed, and the distribution of PM substances in the outer honeycomb structure 5 and the inner honeycomb structure 9 is made uniform throughout. .

そして、排ガス浄化装置１では、外周電極４と電極６との間（外側ハニカム構造体５）および中心電極１０と電極８との間（内側ハニカム構造体９）の双方において高電圧電界が形成される。これにより、外側ハニカム構造体５と内側ハニカム構造体９との双方において排気ガス中のＰＭ物質を効率よく帯電させて確実に捕集することが可能となる。また、排気ガス中のＰＭ物質は負に帯電し易いものである。従って、本実施形態のように、互いに対をなす電極のうち、内側に位置する電極６および中心電極１０を負極（放電極）としておけば、ＰＭ物質が外側の外周電極４や電極８に吸引されるようになるので、ＰＭ物質の分布を全体に均一化して、互いに対をなす電極間におけるＰＭ物質の捕集効率をより一層を向上させることができる。   In the exhaust gas purification apparatus 1, a high-voltage electric field is formed both between the outer peripheral electrode 4 and the electrode 6 (outer honeycomb structure 5) and between the center electrode 10 and the electrode 8 (inner honeycomb structure 9). The As a result, the PM substance in the exhaust gas can be efficiently charged and reliably collected in both the outer honeycomb structure 5 and the inner honeycomb structure 9. Further, the PM substance in the exhaust gas is easily negatively charged. Therefore, as in this embodiment, if the electrode 6 and the center electrode 10 located on the inner side among the electrodes paired with each other are set as the negative electrode (discharge electrode), the PM substance is attracted to the outer peripheral electrode 4 and the electrode 8 on the outer side. As a result, the PM substance distribution can be made uniform as a whole, and the collection efficiency of the PM substance between the paired electrodes can be further improved.

更に、排ガス浄化装置１では、排気ガスが外側ハニカム構造体５と内側ハニカム構造体９とを流通する間に、排気ガス中の酸素や一酸化窒素等がプラズマにより活性化（ラジカル化）され、高い酸化活性をもったオゾン（Ｏ３）、活性化酸素（Ｏ２ −）、二酸化窒素（ＮＯ２）等が生成される。そして、外側ハニカム構造体５および内側ハニカム構造体９のセル内に均一に捕集されたＰＭ物質は、これらの高酸化活性成分と反応して燃焼、焼却される。更に、排ガス浄化装置１では、外側ハニカム構造体５および内側ハニカム構造体９に担持されている酸化触媒の作用により、ＰＭ物質の燃焼が促進される。 Furthermore, in the exhaust gas purification apparatus 1, while exhaust gas flows through the outer honeycomb structure 5 and the inner honeycomb structure 9, oxygen, nitrogen monoxide, and the like in the exhaust gas are activated (radicalized) by plasma, Ozone (O 3 ), activated oxygen (O 2 − ), nitrogen dioxide (NO 2 ), etc. having high oxidation activity are generated. The PM material uniformly collected in the cells of the outer honeycomb structure 5 and the inner honeycomb structure 9 reacts with these highly oxidizing active components and is burned and incinerated. Further, in the exhaust gas purifying apparatus 1, combustion of the PM substance is promoted by the action of the oxidation catalyst supported on the outer honeycomb structure 5 and the inner honeycomb structure 9.

この結果、排ガス浄化装置１によれば、互いに対をなす外周電極４と電極６との間（外側ハニカム構造体５）および互いに対をなす電極８と中心電極１０との間（内側ハニカム構造体９）に均一に捕集されたＰＭ物質が効率よく処理されることになる。そして、浄化容器２の内部で良好に浄化された排気ガスは、排気管Ｌ２を介して外部に排出されることになる。   As a result, according to the exhaust gas purification apparatus 1, the outer electrode 4 and the electrode 6 that make a pair with each other (outer honeycomb structure 5) and the electrode 8 and the center electrode 10 that make a pair with each other (the inner honeycomb structure). The PM substance uniformly collected in 9) is efficiently processed. And the exhaust gas well purified inside the purification container 2 is discharged to the outside through the exhaust pipe L2.

なお、上述のように、排ガス浄化装置１では、外側ハニカム構造体５が内側ハニカム構造体９よりも低いセル密度を有するが、外側ハニカム構造体５と内側ハニカム構造体９とのセル密度の差は、およそ１００〜４００ｃｐｓｉ（ｃｓｐｉ：１平方インチあたりのセル数）程度に定められると好ましい。これにより、セル密度が低い外側ハニカム構造体５における排気ガスの流量が過剰に増加してしまうことを防止して、ハニカム構造体５および９におけるＰＭ物質の分布を全体に均一化することが可能となる。   As described above, in the exhaust gas purification device 1, the outer honeycomb structure 5 has a lower cell density than the inner honeycomb structure 9, but the difference in cell density between the outer honeycomb structure 5 and the inner honeycomb structure 9 is different. Is preferably set to about 100 to 400 cpsi (cpi: number of cells per square inch). Thereby, it is possible to prevent the exhaust gas flow rate from excessively increasing in the outer honeycomb structure 5 having a low cell density, and to uniformize the PM material distribution in the honeycomb structures 5 and 9 as a whole. It becomes.

また、上述の排ガス浄化装置１では、外側ハニカム構造体５と内側ハニカム構造体９とを一体のハニカム構造体とみなした場合、当該一体のハニカム構造体の全長（排気ガスの流れ方向における長さ）にわたって、中心から外周に向かうにつれてセル密度が漸減することになるが、これに限られるものではない。すなわち、本発明では、浄化容器内のハニカム構造体が中心から外周に向かうにつれてセル密度が漸減している領域を少なくとも一部に含んでいればよく、例えばハニカム構造体の中心部のセル密度が浄化容器の入口側で所定長さだけ高く設定されてもよい。更に、上述の排ガス浄化装置１の電極６と電極８との間に、１またはそれ以上の電極対およびハニカム構造体が配置され得ることはいうまでもない。   Further, in the exhaust gas purification device 1 described above, when the outer honeycomb structure 5 and the inner honeycomb structure 9 are regarded as an integral honeycomb structure, the total length of the integral honeycomb structure (the length in the exhaust gas flow direction). ), The cell density gradually decreases from the center toward the outer periphery, but the present invention is not limited to this. That is, in the present invention, it is sufficient that the honeycomb structure in the purification container includes at least part of the region where the cell density gradually decreases from the center toward the outer periphery. For example, the cell density at the center of the honeycomb structure is It may be set higher by a predetermined length on the inlet side of the purification container. Furthermore, it goes without saying that one or more electrode pairs and a honeycomb structure may be disposed between the electrode 6 and the electrode 8 of the exhaust gas purification apparatus 1 described above.

本発明による排ガス浄化装置を示す概略構成図である。It is a schematic block diagram which shows the exhaust gas purification apparatus by this invention. 図１におけるII−II線についての断面図である。It is sectional drawing about the II-II line | wire in FIG.

符号の説明Explanation of symbols

１ 排ガス浄化装置
２ 浄化容器
３，７ 絶縁部材
４ 外周電極
５ 外側ハニカム構造体
６，８ 電極
９ 内側ハニカム構造体
１０ 中心電極
１１ 高圧電源
２１ 入口端部
２２ 出口端部
２３ 拡径部
２４ コーン部
Ｌ１，Ｌ２ 排気管
DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 2 Purification container 3, 7 Insulation member 4 Outer peripheral electrode 5 Outer honeycomb structure 6, 8 Electrode 9 Inner honeycomb structure 10 Central electrode 11 High voltage power supply 21 Inlet end 22 Outlet end 23 Expanded portion 24 Cone L1, L2 exhaust pipe

Claims (3)

プラズマを用いて排気ガスを浄化する排ガス浄化装置において、
排気ガスが導入される浄化容器と、
前記浄化容器内に配置されたハニカム構造体と、
前記ハニカム構造体の中心に配置され、排気ガスの流れ方向に延びる中心電極と、
前記ハニカム構造体の外周に配置された外周電極とを備え、
前記ハニカム構造体は、中心から外周に向かうにつれてセル密度が漸減している領域を含み、
前記中心電極と前記外周電極との間に配置された複数の筒状電極を更に備え、
前記複数の筒状電極には、前記中心電極と対をなす電極と、前記外周電極と対をなす電極とが含まれ、前記中心電極と対をなす電極と前記外周電極と対をなす電極との間には絶縁層が設けられ、かつ前記互いに対をなす電極のうち、内側に位置する電極が負極とされていることを特徴とする排ガス浄化装置。 In an exhaust gas purification device that purifies exhaust gas using plasma,
A purification container into which exhaust gas is introduced;
A honeycomb structure disposed in the purification container;
A central electrode disposed in the center of the honeycomb structure and extending in the flow direction of the exhaust gas;
An outer peripheral electrode disposed on the outer periphery of the honeycomb structure,
The honeycomb structure includes a region where the cell density gradually decreases from the center toward the outer periphery ,
A plurality of cylindrical electrodes disposed between the central electrode and the outer peripheral electrode;
The plurality of cylindrical electrodes include an electrode paired with the central electrode and an electrode paired with the outer peripheral electrode, and an electrode paired with the central electrode and an electrode paired with the outer peripheral electrode; exhaust gas purifying device comprising that you have been provided an insulating layer, and among the electrodes forming the pair with each other, the electrodes located inside the negative electrode during. 前記中心電極を含む一対の電極間に配置された内側ハニカム構造体と、前記外周電極を含む一対の電極間に配置されており、前記内側ハニカム構造体よりも低いセル密度を有する外側ハニカム構造体とを更に備えることを特徴とする請求項１に記載の排ガス浄化装置。   An inner honeycomb structure disposed between a pair of electrodes including the center electrode and an outer honeycomb structure disposed between a pair of electrodes including the outer peripheral electrode and having a lower cell density than the inner honeycomb structure. The exhaust gas purification device according to claim 1, further comprising: 前記内側ハニカム構造体と前記外側ハニカム構造体との間で流体の流通が実質的に規制されていることを特徴とする請求項２に記載の排ガス浄化装置。 The exhaust gas purifying apparatus according to claim 2 , wherein fluid flow is substantially regulated between the inner honeycomb structure and the outer honeycomb structure.
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