JP2006144576A - Nitrogen oxide cleaning device - Google Patents

Nitrogen oxide cleaning device Download PDF

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JP2006144576A
JP2006144576A JP2004332275A JP2004332275A JP2006144576A JP 2006144576 A JP2006144576 A JP 2006144576A JP 2004332275 A JP2004332275 A JP 2004332275A JP 2004332275 A JP2004332275 A JP 2004332275A JP 2006144576 A JP2006144576 A JP 2006144576A
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exhaust gas
reducing agent
nitrogen oxide
wall
contracted
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Masahiro Okajima
正博 岡嶋
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Denso Corp
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Denso Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and simple NOx cleaning device, in which soot and viscous components in exhaust gas are not adhered to the periphery of an injection port of an adding valve adding reducing agent to keep normal injection of the reducing agent, in an NOx cleaning device for a diesel engine or a lean-burn gasoline engine. <P>SOLUTION: The NOx cleaning device comprises: an NOx cleaning catalyst; and a reducing agent adding means for adding the reducing agent for reducing the NOx; and a contraction wall 40 disposed upstream the adding valve 32 so as to contract the flow of the exhaust gas E to direct to a tip 32a of the adding valve 32. A plurality of through holes 44 through which the soot in the exhaust gas passes are perforated in the contraction wall 40. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、ディーゼルエンジンまたはリーンバーンガソリンエンジンなどの酸素過剰雰囲気の排気ガスを排出する内燃機関の排気系に介挿する窒素酸化物(以下、NOxと記す。)浄化装置に関する。   The present invention relates to a nitrogen oxide (hereinafter referred to as NOx) purifying device inserted in an exhaust system of an internal combustion engine that exhausts exhaust gas in an oxygen-rich atmosphere such as a diesel engine or a lean burn gasoline engine.

従来内燃機関には排気を浄化する排気浄化手段が設置されている。例えば、NOx吸蔵還元型触媒によりNOxを還元して排気を浄化する場合のように、排気浄化手段を機能させて排気を浄化するためには、燃料などの還元剤からなる添加剤を必要とする。このような排気浄化の方法として、内燃機関の排気管に燃料を噴射する方法が知られている(例えば、特許文献1など)。   Conventional internal combustion engines have been provided with exhaust purification means for purifying exhaust. For example, as in the case of purifying exhaust gas by reducing NOx with a NOx occlusion reduction type catalyst, in order to purify exhaust gas by functioning the exhaust gas purification means, an additive comprising a reducing agent such as fuel is required. . As such an exhaust purification method, a method of injecting fuel into an exhaust pipe of an internal combustion engine is known (for example, Patent Document 1).

上記のように燃料を添加剤として排気管内に添加する方法では、添加剤供給手段の添加弁は常時排気ガス中に曝されることとなる。このため、図7(b)に示すように、排気ガスE中に含まれる例えばすすや粘性成分等Sが添加弁100の噴射口の周辺Jに付着堆積して、添加弁100からの還元剤Kの噴霧を異常なものとすることがある。つまり、添加弁の噴射口がすすなどによって目詰まりし、排気中に供給する燃料が低減してしまって排気浄化手段が十分に機能しなくなるおそれがある。   In the method of adding fuel as an additive into the exhaust pipe as described above, the addition valve of the additive supply means is always exposed to the exhaust gas. For this reason, as shown in FIG. 7B, for example, soot and viscous components S contained in the exhaust gas E adhere to and accumulate on the periphery J of the injection valve 100, and the reducing agent from the addition valve 100. K spraying may be abnormal. In other words, the injection port of the addition valve may be clogged with soot and the like, and the fuel supplied into the exhaust gas may be reduced, and the exhaust gas purification unit may not function sufficiently.

例えば排気浄化手段としてNOx還元触媒を用いた場合には、排気の空燃比をリッチ側へ変化させることができなくなる。そのため、NOxの還元が困難になり、NOx排出量の低減を図ることができないという問題が生じる。また、排気浄化手段として排気中に含まれる微粒子を捕集するパティキュレートフィルタを用いた場合には、フィルタの温度を高めることができない。そのため、捕集された微粒子の燃焼が不十分となり、フィルタに微粒子が堆積して圧力損失の増大によるドライバビリティや燃費の悪化を招くという問題が生じる。
特開平05−302509号公報
For example, when a NOx reduction catalyst is used as the exhaust gas purification means, the air-fuel ratio of the exhaust gas cannot be changed to the rich side. This makes it difficult to reduce NOx, resulting in a problem that the amount of NOx emission cannot be reduced. Further, when a particulate filter that collects particulates contained in the exhaust is used as the exhaust purification means, the temperature of the filter cannot be increased. Therefore, combustion of the collected fine particles becomes insufficient, and there arises a problem that the fine particles accumulate on the filter, resulting in deterioration of drivability and fuel consumption due to an increase in pressure loss.
Japanese Patent Laid-Open No. 05-302509

本発明は上記の問題点を解決すべくなされたもので、ディーゼルエンジンまたはリーンバーンガソリンエンジンなどのNOx浄化装置において、排気ガス中のすすや粘性成分が還元剤を添加する添加弁の噴射口周辺に付着しないで、正常な還元剤の噴射を維持できる安価で簡便なNOx浄化装置を提供することを課題とする。   The present invention has been made to solve the above problems, and in a NOx purification device such as a diesel engine or a lean burn gasoline engine, soot and viscous components in exhaust gas are added around the injection port of an addition valve to which a reducing agent is added. It is an object of the present invention to provide an inexpensive and simple NOx purification device that can maintain normal injection of a reducing agent without adhering to the catalyst.

本発明の窒素酸化物浄化装置は、窒素酸化物浄化用触媒と、この窒素酸化物浄化用触媒の上流側に窒素酸化物を還元する還元剤を添加する還元剤添加手段とを備え、酸素過剰雰囲気の排ガスを排出する内燃機関の排気系で窒素酸化物を浄化する窒素酸化物浄化装置であって、還元剤添加手段の還元剤添加弁の先端に指向するように排気ガスの流れを縮流する縮流壁を還元剤添加弁の上流に備えることを特徴とする。   The nitrogen oxide purifying apparatus of the present invention comprises a nitrogen oxide purifying catalyst, and a reducing agent addition means for adding a reducing agent for reducing nitrogen oxides upstream of the nitrogen oxide purifying catalyst, and an oxygen excess A nitrogen oxide purification device that purifies nitrogen oxides in an exhaust system of an internal combustion engine that discharges exhaust gas in an atmosphere, and the exhaust gas flow is reduced so as to be directed to the tip of the reducing agent addition valve of the reducing agent addition means The contracted flow wall is provided upstream of the reducing agent addition valve.

本発明の窒素酸化物浄化装置において、縮流壁には排気ガス中のすすを通過させる複数の通孔を穿設することが望ましい。通孔の径は1〜5mmであることが好ましく、また、穿設された通孔の径は排気管の内周側から軸心に近接するほど順に大きくすることが好ましい。   In the nitrogen oxide purifying apparatus of the present invention, it is desirable to drill a plurality of through holes through which the soot in the exhaust gas passes through the contracted wall. The diameter of the through hole is preferably 1 to 5 mm, and the diameter of the formed through hole is preferably increased in order from the inner peripheral side of the exhaust pipe to the axial center.

上記のような縮流壁において、排気ガスを通過させる開口部の面積は、排気管の断面積の0.1〜0.7であることが望ましい。   In the contracted wall as described above, the area of the opening through which the exhaust gas passes is desirably 0.1 to 0.7 of the cross-sectional area of the exhaust pipe.

本発明のNOx浄化装置は、排気管内の還元剤添加弁の上流に添加弁の先端に指向するように排気ガスの流れを縮流する縮流壁を備えている。内燃機関から排出された排気ガスはこの縮流壁に沿って縮流され、還元剤を噴射する添加弁の先端に形成されている噴射口周辺に衝突する。排気ガスは、縮流されることによりその流速は高まるので、この高速の排気ガスが噴射口周辺へのすすの付着・堆積を抑制する。従って、添加弁の噴射口からは常に正常なパターンで還元剤を噴霧することができ、排気ガス中のNOxの浄化効率を安定化することができる。   The NOx purification device of the present invention includes a contracted wall that contracts the flow of exhaust gas so as to be directed to the tip of the addition valve upstream of the reducing agent addition valve in the exhaust pipe. The exhaust gas discharged from the internal combustion engine is compressed along the contracted wall and collides with the vicinity of the injection port formed at the tip of the addition valve that injects the reducing agent. Since the exhaust gas is contracted to increase its flow velocity, the high-speed exhaust gas suppresses soot adhesion and accumulation around the injection port. Therefore, the reducing agent can always be sprayed in a normal pattern from the injection port of the addition valve, and the purification efficiency of NOx in the exhaust gas can be stabilized.

また、縮流壁にはすすを通過させる通孔を設けているので、排気ガス中のすすはこの通孔を通過することができる。このため、排気ガスは縮流壁により炭酸ガスやNOxなどを含むガス流と、未燃焼のすすとを分離するとともにガス流のみを添加弁の噴射口周辺へ向けて高速化することができる。この結果、噴射口周辺へのすすの堆積を一層抑制することができる。   Further, since the through hole through which the soot passes is provided in the contracted wall, the soot in the exhaust gas can pass through the through hole. For this reason, the exhaust gas can separate the gas flow containing carbon dioxide gas, NOx and the like from the unburned soot by the contracted wall and speed up only the gas flow toward the injection valve periphery of the addition valve. As a result, it is possible to further suppress soot accumulation around the injection port.

さらに、排気ガスを通過させる縮流壁の開口部面積は、排気管の断面積の0.1〜0.7である。排気管の断面積に対する縮流壁の開口部面積の比率を大きくすると、縮流壁の開口部における排気ガスの流速は急速に低下するとともに、縮流壁による排気ガスの圧力損失も急激に低下する。すなわち、開口部面積を排気管の断面積の0.1〜0.7とすることで、縮流壁に沿って流れる排気ガスの流速をできるだけ高く維持しながら、圧力損失を小さく抑えることができる。   Furthermore, the opening area of the contracted wall through which the exhaust gas passes is 0.1 to 0.7 of the cross-sectional area of the exhaust pipe. When the ratio of the opening area of the contracted wall to the cross-sectional area of the exhaust pipe is increased, the exhaust gas flow velocity at the opening of the contracted wall rapidly decreases and the pressure loss of the exhaust gas due to the contracted wall also decreases rapidly. To do. That is, by setting the area of the opening to 0.1 to 0.7 of the cross-sectional area of the exhaust pipe, the pressure loss can be kept small while maintaining the flow velocity of the exhaust gas flowing along the contracted flow wall as high as possible. .

本発明のNOx浄化装置についてその望ましい実施の形態を図を参照しながら説明する。   A preferred embodiment of the NOx purification device of the present invention will be described with reference to the drawings.

図1は、本発明になるNOx浄化装置の一実施の形態の全体構成を示す概要図である。   FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of a NOx purification device according to the present invention.

本発明のNOx浄化装置1は、NOx浄化用触媒20と、このNOx浄化用触媒20の上流側にNOxを還元する還元剤を添加する還元剤添加手段30とを備え、酸素過剰雰囲気の排ガスを排出する内燃機関の排気系でNOxを浄化するNOx浄化装置であって、排気管10内に還元剤添加手段30の還元剤添加弁32の先端32aに指向するように排ガスEの流れを縮流する縮流壁40を還元剤添加弁32の上流に備える。   The NOx purification device 1 of the present invention includes a NOx purification catalyst 20 and a reducing agent addition means 30 for adding a reducing agent for reducing NOx on the upstream side of the NOx purification catalyst 20, and exhaust gas in an oxygen-excess atmosphere. A NOx purifying device that purifies NOx by an exhaust system of an exhausting internal combustion engine, and the flow of exhaust gas E is contracted in the exhaust pipe 10 so as to be directed to the tip 32a of the reducing agent addition valve 32 of the reducing agent addition means 30. A contracting wall 40 is provided upstream of the reducing agent addition valve 32.

還元剤添加手段30は、還元剤Gを貯留する還元剤タンク34と、還元剤Gを排気管10内へその先端32aから噴射する添加弁32とを有している。還元剤Gは、エンジン燃焼用燃料タンク50から供給ポンプ50pの付勢によって還元剤タンク34へ適宜供給されるようになっている。   The reducing agent addition means 30 includes a reducing agent tank 34 that stores the reducing agent G, and an addition valve 32 that injects the reducing agent G into the exhaust pipe 10 from its tip 32a. The reducing agent G is appropriately supplied from the engine combustion fuel tank 50 to the reducing agent tank 34 by energizing the supply pump 50p.

本発明の特徴である縮流壁について図2によって説明する。(a)は排気管10内に設置した縮流壁40のX−X断面((b)参照)の模式図であり、(b)は(a)のY視模式図である。縮流壁40は、例えば添加弁32の噴出口32aを頂点とする三角錐状の一側面である第1の縮流壁40aと、他の側面である第2の縮流壁40bとからなり、第1の縮流壁40aと第2の縮流壁40bとを(b)の斜線で示すような開口部42を形成するように、所定の距離を隔てて対向配置して排気管10の内周面に溶接あるいは嵌合などの適宜の方法で固設されている。なお、縮流壁40は、後述する開口部面積が確保できれば1つの円錐台状の一体物であっても良い。   The contracted wall which is a feature of the present invention will be described with reference to FIG. (A) is a schematic diagram of the XX cross section (refer to (b)) of the contracted wall 40 installed in the exhaust pipe 10, (b) is a schematic view in Y view of (a). The contracted flow wall 40 includes, for example, a first contracted wall 40a that is one side surface of a triangular pyramid having the spout 32a of the addition valve 32 as an apex, and a second contracted wall 40b that is the other side surface. The first contracted wall 40a and the second contracted wall 40b are arranged to face each other with a predetermined distance so as to form an opening 42 as shown by the oblique lines in FIG. The inner peripheral surface is fixed by an appropriate method such as welding or fitting. Note that the contracted wall 40 may be a single truncated cone-shaped one as long as an opening area described later can be secured.

縮流壁40は、耐熱性や耐食性などを考慮して排気管10と同様にステンレスで形成するとよい。   The contracted wall 40 is preferably formed of stainless steel in the same manner as the exhaust pipe 10 in consideration of heat resistance and corrosion resistance.

図2に示す実施の形態では、第1の縮流壁40aに複数の通孔44が穿設されている。通孔44は、排気管10の内周面近傍の通孔44aの径よりも軸心に近い通孔44の径の方が順に大きくなるように穿設されており、排気ガス流の中央近傍の44eで最も大きくなっている。これは本実施の形態では排気管の軸心部に近いほど排気ガスE中のすすの濃度が高くなるからである。ここで、通孔44の直径は1〜5mmとすることが望ましい。通孔径が1mm未満ではすすが通孔を閉塞する虞があるので好ましくない。一方、5mmを越えると添加弁先端に衝突する気流を高速化できないことがあるので適当ではない。より好ましくは2〜3mmである。なお、通孔44は、その各々の軸線が排気管の軸線に平行となるように穿設されている。   In the embodiment shown in FIG. 2, a plurality of through holes 44 are formed in the first contracted wall 40a. The through-hole 44 is formed so that the diameter of the through-hole 44 closer to the axial center becomes larger in order than the diameter of the through-hole 44a in the vicinity of the inner peripheral surface of the exhaust pipe 10, and near the center of the exhaust gas flow. No. 44e is the largest. This is because, in the present embodiment, the concentration of soot in the exhaust gas E increases as it is closer to the axial center of the exhaust pipe. Here, the diameter of the through hole 44 is desirably 1 to 5 mm. If the through-hole diameter is less than 1 mm, soot is not preferable because the through-hole may be blocked. On the other hand, if it exceeds 5 mm, the airflow that collides with the tip of the addition valve may not be accelerated, which is not appropriate. More preferably, it is 2-3 mm. The through holes 44 are drilled so that their respective axes are parallel to the axis of the exhaust pipe.

また、添加弁32の先端32a周辺へは排気ガスEをできるだけ高速で衝突させることが望ましく、そのためには縮流壁40の開口部面積Cを小さくするとよい。ここで、縮流壁40の開口部面積Cとは、図2(b)に斜線で示す開口部42の二次元の面積Aと第1の縮流壁40aに穿設された全ての通孔44の合計面積Bとの和である。   Further, it is desirable that the exhaust gas E collide with the periphery of the tip 32a of the addition valve 32 as fast as possible. For this purpose, the opening area C of the contracted wall 40 may be reduced. Here, the opening area C of the contracted wall 40 refers to the two-dimensional area A of the opening 42 shown by hatching in FIG. 2B and all through holes formed in the first contracted wall 40a. 44 and the total area B.

開口部を増やして排気管10の断面積Dに対する開口部面積Cの比率(C/D:以後、面積比率という。)を増加すると、図4(b)に示すように開口部42における排気ガスeの流速Vは減少する。また、排気ガスEの流路内に縮流壁40を設けることで排気ガスEの圧力は低下して圧力損失ΔPを生じる。圧力損失ΔPは、開口部を増やせば図4(c)に示すように面積比率の増加に伴い低下する。すなわち、排気ガスe(E)が添加弁の先端32aへ衝突してすすを堆積させないために必要な最低の流速vに対応する面積比率r1と、圧力損失ΔPの許容最大値Δpに対応する面積比率r2との間が最適面積比率であり、例えば、0.1〜0.7とすることができる。この場合には、面積比率が0.1未満では圧力損失が大きくなるために不適当であり、また、0.7を越えると排気ガスの流速が低くなるので好ましくないわけである。   When the ratio of the opening area C to the cross-sectional area D of the exhaust pipe 10 is increased by increasing the number of openings (C / D: hereinafter referred to as area ratio), the exhaust gas in the opening 42 as shown in FIG. The flow velocity V of e decreases. Further, by providing the contracted wall 40 in the flow path of the exhaust gas E, the pressure of the exhaust gas E is reduced and a pressure loss ΔP is generated. If the number of openings is increased, the pressure loss ΔP decreases as the area ratio increases as shown in FIG. That is, the area ratio r1 corresponding to the minimum flow velocity v necessary to prevent the exhaust gas e (E) from colliding with the tip 32a of the addition valve and depositing soot and the area corresponding to the allowable maximum value Δp of the pressure loss ΔP. The ratio between the ratio r2 and the optimum area ratio is 0.1 to 0.7, for example. In this case, if the area ratio is less than 0.1, the pressure loss increases, which is inappropriate. If it exceeds 0.7, the flow rate of the exhaust gas decreases, which is not preferable.

以上のように構成される本実施の形態の作用について図3を参照しながらより詳しく説明する。   The operation of the present embodiment configured as described above will be described in more detail with reference to FIG.

図3(a)は、すすSを含む排気ガスEが縮流壁40内に侵入する直前の様子を模式的に示した断面図である。還元剤添加弁32はそのノズル先端32aから還元剤Gを正常に噴霧している。   FIG. 3A is a cross-sectional view schematically showing a state immediately before the exhaust gas E containing soot S enters the contracted wall 40. The reducing agent addition valve 32 normally sprays the reducing agent G from the nozzle tip 32a.

時間の経過により、すすSを含んだ排気ガスEは図3(b)に示すように縮流壁40によってノズル先端32aを指向するように絞られる。このため、排気ガスEのガス成分eは矢印feのように高速気流となってノズル先端32aの周辺に衝突する。   As time passes, the exhaust gas E containing soot S is throttled so as to be directed to the nozzle tip 32a by the contracted wall 40 as shown in FIG. For this reason, the gas component e of the exhaust gas E becomes a high-speed air current as shown by the arrow fe and collides with the periphery of the nozzle tip 32a.

一方、排気ガスE中のすすSは、質量があるのでガス成分eによる高速気流feには乗らないで、図3(b)のHで囲むように、第1の縮流壁40aに穿設されている通孔44を通過して排気ガスEの流れに沿って排気管の軸線とほぼ平行に流通する。図3(c)はこれらの作用を1つの通孔44について拡大して示したものである。排気ガスEは第1の縮流壁40aに衝突して、ごく一部は矢印fe’のように通孔44を通過するが、大半は矢印feの主流となって縮流壁に沿って開口部42からノズル先端32aに向かって流出する。ところが前述のようにすすSは質量があるので主流feに乗って上昇することができずに、矢印fsのように通孔44を貫通して排気管の軸線Zとほぼ平行に流通する。   On the other hand, since the soot S in the exhaust gas E has a mass, the soot S does not get on the high-speed air flow fe due to the gas component e, and is formed in the first contracted wall 40a so as to be surrounded by H in FIG. It passes through the through-hole 44 and flows along the flow of the exhaust gas E substantially parallel to the axis of the exhaust pipe. FIG. 3 (c) shows these actions in an enlarged manner for one through hole 44. The exhaust gas E collides with the first contracted wall 40a, and a small part passes through the through hole 44 as indicated by the arrow fe ′, but most of the exhaust gas E becomes the main stream of the arrow fe and opens along the contracted wall. Outflow from the portion 42 toward the nozzle tip 32a. However, as described above, since the soot S has a mass, it cannot rise on the main stream fe, but passes through the through hole 44 and flows substantially parallel to the axis Z of the exhaust pipe as indicated by an arrow fs.

第2の縮流壁側に流通してきたり、あるいは粒径が大きいくて通孔44を通過できなかったすすSは、矢印fsのようにノズル先端32aに指向することなく排気ガスEの流れに沿って縮流壁40の開口部42から流出する。ノズル先端32aの近傍ではすすSの濃度が極めて低くなっているので、上述した高速気流の衝突と相まって、ノズル先端32aへのすすSの堆積を従来に比べて大幅に抑制することができる。このため、還元剤Gの噴霧は常に正常な状態に維持されるので、NOx浄化用触媒の浄化性能を高い状態で安定させることができる。   The soot S that has circulated to the second contracted wall side or has failed to pass through the through hole 44 due to its large particle size does not flow toward the nozzle tip 32a as indicated by the arrow fs. Along the outlet 42 of the contracted wall 40. Since the concentration of soot S is extremely low in the vicinity of the nozzle tip 32a, the soot S accumulation on the nozzle tip 32a can be greatly suppressed as compared with the conventional case, coupled with the collision of the high-speed air flow described above. For this reason, since the spray of the reducing agent G is always maintained in a normal state, the purification performance of the NOx purification catalyst can be stabilized in a high state.

なお、本発明のNOx浄化装置は、上記の実施の形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲で変更することも可能である。   The NOx purification device of the present invention is not limited to the above-described embodiment, and can be changed without departing from the spirit of the present invention.

例えば、第1の縮流壁に図5(a)のように図2(b)に示す実施の形態よりも更に多くの通孔を設けてもよい。また、上記の実施の形態では、第1の縮流壁40aのみにすすを通過させる通孔44を設けたが、図5(b)に示すように第2の縮流壁40bにも通孔44を穿設してもよい。このように第1と第2の両方の縮流壁に通孔を設けることにより高濃度のすすが発生する場合などに、すすの通孔44への排出性が向上できて好適である。   For example, more through holes may be provided in the first contracted wall as shown in FIG. 5A than in the embodiment shown in FIG. Further, in the above embodiment, the through hole 44 through which soot passes only through the first contracted wall 40a is provided. However, as shown in FIG. 5B, the through hole is also formed in the second contracted wall 40b. 44 may be drilled. Thus, by providing a through hole in both the first and second contracted walls, soot having a high concentration is generated, it is preferable because the discharge property to the soot through hole 44 can be improved.

さらに、上記の実施の形態では、縮流壁40を第1の縮流壁40aと第2の縮流壁40bとを対向して配置することとしたが、縮流壁40を2部材に分けることなく、例えば、図6の(a)や(b)などのように円錐台形状の一部材として形成してもよい。一部材とすることで排気管内への配設が容易となり、生産性を向上させることができる。   Furthermore, in the above embodiment, the contracted wall 40 is arranged so that the first contracted wall 40a and the second contracted wall 40b face each other, but the contracted wall 40 is divided into two members. For example, you may form as one member of truncated cone shape like (a), (b), etc. of FIG. By using one member, the arrangement in the exhaust pipe is facilitated, and the productivity can be improved.

また、上記の実施の形態では還元剤としてエンジン燃焼用の燃料を使用することとして説明したが、還元剤としてのエンジン燃焼用の燃料は、軽油、ガソリンおよびLPGあるいはDMEなどの液化ガス燃料等を例示することができる。さらに、これの燃料にに代えて尿素を添加してもよい。   In the above embodiment, the fuel for engine combustion is used as the reducing agent. However, the fuel for engine combustion as the reducing agent is light oil, gasoline, and liquefied gas fuel such as LPG or DME. It can be illustrated. Further, urea may be added instead of the fuel.

以上のように本発明のNOx浄化装置は、縮流壁という極めて安価で簡便な部材を排気管内へ配設するだけで、排気ガス中に含まれるすすや粘性成分が添加弁の先端周辺に付着・堆積することを抑制でき、還元剤を常に正常な状態で噴霧することができる。従って、NOx浄化用触媒の浄化性能を安定して高い状態に維持することができる。   As described above, the NOx purifying apparatus of the present invention can attach soot and viscous components contained in the exhaust gas around the tip of the addition valve only by disposing a very inexpensive and simple member called a contracted wall in the exhaust pipe. -It can suppress depositing and can always spray a reducing agent in a normal state. Therefore, the purification performance of the NOx purification catalyst can be stably maintained at a high level.

本発明の窒素酸化物処理装置は、ディーゼルエンジンまたはリーンバーンガソリンエンジン等の酸素過剰雰囲気の排ガスを排出する内燃機関に用いて好適である。   The nitrogen oxide treatment apparatus of the present invention is suitable for use in an internal combustion engine that exhausts exhaust gas in an oxygen-rich atmosphere, such as a diesel engine or a lean burn gasoline engine.

本発明の一実施の形態の構成を示す概要図である。It is a schematic diagram which shows the structure of one embodiment of this invention. 縮流壁の構成を説明する説明図である。(a)はX−X断面を示す模式図であり、(b)はY視模式図である。It is explanatory drawing explaining the structure of a contracted wall. (A) is a schematic diagram which shows a XX cross section, (b) is a Y view schematic diagram. 縮流壁の作用を説明する説明図である。(a)は排気ガスEが縮流壁を通過する前の状態を示す。添加弁32は還元剤を正常に噴霧している。(b)は排気ガスEが縮流壁を通過している様子を示している。添加弁の先端32aにすすSが堆積しないので添加弁32は還元剤を正常に噴霧することができる。(c)は通孔44を排気ガスEが通過する様子を拡大して示した概念図である。It is explanatory drawing explaining the effect | action of a contracted wall. (A) shows the state before the exhaust gas E passes through the contracted flow wall. The addition valve 32 normally sprays the reducing agent. (B) shows a state in which the exhaust gas E passes through the contracted flow wall. Since soot S does not accumulate on the tip 32a of the addition valve, the addition valve 32 can normally spray the reducing agent. (C) is a conceptual diagram showing an enlarged view of the exhaust gas E passing through the through hole 44. 最適な開口部面積比率(C/D)を説明する説明図である。(a)は面積比率の定義を説明する図である。(b)は排気ガスeの流速Vと面積比率との関係を概念的に示すグラフである。(c)は排気ガスEの圧力損失ΔPと面積比率との関係を概念的に示すグラフである。It is explanatory drawing explaining the optimal opening part area ratio (C / D). (A) is a figure explaining the definition of an area ratio. (B) is a graph conceptually showing the relationship between the flow velocity V of the exhaust gas e and the area ratio. (C) is a graph conceptually showing the relationship between the pressure loss ΔP of the exhaust gas E and the area ratio. 縮流壁に穿設された通孔についてその他の例を示す模式図である。(a)は第1の縮流壁にのみ更に多くの通孔を穿設したものであり、(b)は第2の縮流壁にも通孔を穿設したものである。It is a schematic diagram which shows another example about the through-hole drilled in the contracted wall. (A) is one in which more through holes are made only in the first contracted wall, and (b) is one in which through holes are also made in the second contracted wall. 縮流壁のその他の形状を例示する斜視図である。(a)は一体成形され先端部のみに開口部を有するものであり、(b)は側部にも開口部を有するものである。It is a perspective view which illustrates other shapes of a contraction wall. (A) is integrally formed and has an opening at the tip only, and (b) has an opening at the side. 添加弁から還元剤を噴霧する様子を示す模式図である。(a)は正常噴霧であり、(b)は添加弁の先端にすすが堆積したことによる異常噴霧の状態を示す模式図である。It is a schematic diagram which shows a mode that a reducing agent is sprayed from an addition valve. (A) is a normal spray, (b) is a schematic diagram which shows the state of the abnormal spray by soot having accumulated on the front-end | tip of an addition valve.

符号の説明Explanation of symbols

1:窒素酸化物浄化装置 10:排気管 20窒素酸化物浄化用触媒 30:還元剤添加手段 32:還元剤添加弁 40:縮流壁 42:開口部 44:通孔50:燃料タンク E:排気ガス G:燃料(還元剤) DESCRIPTION OF SYMBOLS 1: Nitrogen oxide purification apparatus 10: Exhaust pipe 20 Nitrogen oxide purification catalyst 30: Reducing agent addition means 32: Reducing agent addition valve 40: Shrinkage wall 42: Opening 44: Through hole 50: Fuel tank E: Exhaust Gas G: Fuel (reducing agent)

Claims (5)

窒素酸化物浄化用触媒と、該窒素酸化物浄化用触媒の上流側に窒素酸化物を還元する還元剤を添加する還元剤添加手段とを備え、酸素過剰雰囲気の排気ガスを排出する内燃機関の排気系で窒素酸化物を浄化する窒素酸化物浄化装置であって、
前記還元剤添加手段の還元剤添加弁の先端に指向するように排気ガスの流れを縮流する縮流壁を前記還元剤添加弁の上流に備えることを特徴とする窒素酸化物浄化装置。
An internal combustion engine comprising: a nitrogen oxide purifying catalyst; and a reducing agent adding means for adding a reducing agent for reducing nitrogen oxide upstream of the nitrogen oxide purifying catalyst, and exhausting exhaust gas in an oxygen-excess atmosphere. A nitrogen oxide purification device that purifies nitrogen oxides in an exhaust system,
A nitrogen oxide purifier comprising a contraction wall for contracting an exhaust gas flow upstream of the reducing agent addition valve so as to be directed to a tip of the reducing agent addition valve of the reducing agent addition means.
前記縮流壁は前記排ガス中のすすを通過させる複数の通孔を穿設した請求項1に記載の窒素酸化物浄化装置。   The nitrogen oxide purification apparatus according to claim 1, wherein the contracted wall has a plurality of through holes through which soot in the exhaust gas passes. 前記通孔の径は1〜5mmである請求項2に記載の窒素酸化物浄化装置。   The nitrogen oxide purification apparatus according to claim 2, wherein the diameter of the through hole is 1 to 5 mm. 前記縮流壁の前記排気ガスを流通する開口部の面積は排気管の断面積の0.1〜0.5である請求項1〜3のいずれかに記載の窒素酸化物浄化装置。   The nitrogen oxide purification apparatus according to any one of claims 1 to 3, wherein an area of the opening through which the exhaust gas flows in the contracted wall is 0.1 to 0.5 of a cross-sectional area of the exhaust pipe. 前記排気ガスの前記縮流壁による圧力損失が2.5kPa未満である請求項1〜4のいずれかに記載の窒素酸化物浄化装置。   The nitrogen oxide purification apparatus according to any one of claims 1 to 4, wherein a pressure loss due to the contracted wall of the exhaust gas is less than 2.5 kPa.
JP2004332275A 2004-11-16 2004-11-16 Nitrogen oxide cleaning device Withdrawn JP2006144576A (en)

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WO2011114721A1 (en) * 2010-03-19 2011-09-22 日野自動車株式会社 Exhaust gas purification device
JP2013540927A (en) * 2010-08-18 2013-11-07 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 Compact exhaust gas treatment device with addition of reaction agent
JP2017141740A (en) * 2016-02-10 2017-08-17 トヨタ自動車株式会社 Exhaust emission control device of internal combustion engine
JP2017198097A (en) * 2016-04-25 2017-11-02 トヨタ自動車株式会社 Exhaust emission control device for internal combustion engine
JP2021038701A (en) * 2019-09-03 2021-03-11 トヨタ自動車株式会社 Exhaust passage
JP2021088984A (en) * 2019-12-06 2021-06-10 トヨタ自動車株式会社 Exhaust passage

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011114721A1 (en) * 2010-03-19 2011-09-22 日野自動車株式会社 Exhaust gas purification device
CN102791977A (en) * 2010-03-19 2012-11-21 日野自动车株式会社 Exhaust gas purification device
CN102791977B (en) * 2010-03-19 2016-04-27 日野自动车株式会社 Exhaust gas purifying device
US9650938B2 (en) 2010-03-19 2017-05-16 Hino Motors, Ltd. Exhaust emission control device
JP2013540927A (en) * 2010-08-18 2013-11-07 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 Compact exhaust gas treatment device with addition of reaction agent
JP2017141740A (en) * 2016-02-10 2017-08-17 トヨタ自動車株式会社 Exhaust emission control device of internal combustion engine
JP2017198097A (en) * 2016-04-25 2017-11-02 トヨタ自動車株式会社 Exhaust emission control device for internal combustion engine
JP2021038701A (en) * 2019-09-03 2021-03-11 トヨタ自動車株式会社 Exhaust passage
JP7351148B2 (en) 2019-09-03 2023-09-27 トヨタ自動車株式会社 exhaust passage
JP2021088984A (en) * 2019-12-06 2021-06-10 トヨタ自動車株式会社 Exhaust passage
JP7205452B2 (en) 2019-12-06 2023-01-17 トヨタ自動車株式会社 exhaust passage

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