JPH08200046A - Exhaust emission control device for engine - Google Patents
Exhaust emission control device for engineInfo
- Publication number
- JPH08200046A JPH08200046A JP712495A JP712495A JPH08200046A JP H08200046 A JPH08200046 A JP H08200046A JP 712495 A JP712495 A JP 712495A JP 712495 A JP712495 A JP 712495A JP H08200046 A JPH08200046 A JP H08200046A
- Authority
- JP
- Japan
- Prior art keywords
- compressed air
- catalyst
- exhaust
- nozzle
- passage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Exhaust Gas After Treatment (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、エンジンの排気浄化装
置に関し、特に、エンジンの排気中に含まれる窒素酸化
物を、排気通路に介装された触媒で除去する排気浄化装
置において、還元剤の霧化供給技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust emission control system for an engine, and more particularly to a reducing agent for an exhaust emission control system for removing nitrogen oxides contained in exhaust gas of an engine with a catalyst interposed in an exhaust passage. Related to atomization supply technology.
【0002】[0002]
【従来の技術】エンジンの排気中に含まれる窒素酸化物
(NOx)濃度を低下させる有効な手段として、排気還
流(EGR)を行うことが良くしられているが、エンジ
ンの排気通路に触媒を介装し、この触媒にてNOxを処
理する方法も考えられる。この場合、NOxの効率的な
還元を図るため、触媒の上流側の排気通路に還元剤とし
ての軽油を添加する装置を設けたものが提案されている
(実開平5−87218号公報参照)。Background Art Exhaust gas recirculation (EGR) is well known as an effective means for reducing the concentration of nitrogen oxides (NOx) contained in the exhaust gas of an engine. A method of interposing and treating NOx with this catalyst is also conceivable. In this case, in order to efficiently reduce NOx, it has been proposed to provide a device for adding light oil as a reducing agent in the exhaust passage on the upstream side of the catalyst (see Japanese Utility Model Laid-Open No. 5-87218).
【0003】[0003]
【発明が解決しようとする課題】ところで、このような
排気浄化装置においては、触媒の還元剤である軽油を触
媒の前面にむらなく添加するため、軽油の霧化を促進し
て、その気化・混合性を向上する手段を設ける必要があ
る。この軽油の霧化には、圧縮空気(アシストエア)を
利用して軽油を噴霧する方法があるが、空気温度が低い
ため、排気温度の低下を来し、触媒の活性化に支障を来
し、触媒のNOx低減能力の低下を来すという問題点が
あった。By the way, in such an exhaust emission control device, since the light oil, which is the reducing agent of the catalyst, is evenly added to the front surface of the catalyst, the atomization of the light oil is promoted and its vaporization It is necessary to provide means for improving the mixing property. There is a method of atomizing light oil by using compressed air (assist air) for atomization of light oil, but since the air temperature is low, the exhaust temperature decreases, which hinders the activation of the catalyst. However, there is a problem in that the NOx reduction ability of the catalyst is reduced.
【0004】そこで、本発明は以上のような従来の問題
点に鑑み、エンジンの排気中に含まれる窒素酸化物を、
排気通路に介装された触媒で除去する排気浄化装置にお
いて、還元剤添加時に供給される圧縮空気による排気温
度低下を防止し、触媒の活性化に支障を来さないように
して、触媒のNOx低減能力の低下を防止することを目
的とする。In view of the above-mentioned conventional problems, the present invention therefore eliminates nitrogen oxides contained in the exhaust gas of an engine.
In an exhaust gas purification device that removes with a catalyst installed in an exhaust passage, the exhaust gas temperature is prevented from lowering due to compressed air supplied when a reducing agent is added, and activation of the catalyst is not hindered. The purpose is to prevent the reduction ability from decreasing.
【0005】[0005]
【課題を解決するための手段】このため、本発明は、エ
ンジンの排気中に含まれる窒素酸化物を、排気通路に介
装された触媒で除去する排気浄化装置において、前記触
媒の上流側の排気通路に還元剤を添加するためのノズル
と、前記ノズルに還元剤噴霧用の圧縮空気を導入する圧
縮空気導入装置と、を含んで構成し、前記圧縮空気導入
装置を、圧縮空気供給源と、該圧縮空気供給源から供給
される圧縮空気をノズルに導入する圧縮空気導入通路
と、を含んで構成し、前記圧縮空気導入通路の一部を、
前記触媒下流側排気通路を構成する排気管と、該排気管
外周部に配設された外周管との間に形成される筒状通路
により形成するようにした。Therefore, according to the present invention, in an exhaust gas purifying apparatus for removing nitrogen oxides contained in the exhaust gas of an engine by a catalyst interposed in an exhaust passage, the exhaust gas purifying apparatus is provided on the upstream side of the catalyst. A nozzle for adding a reducing agent to the exhaust passage, and a compressed air introducing device for introducing compressed air for reducing agent spraying to the nozzle, the compressed air introducing device, a compressed air supply source And a compressed air introduction passage for introducing compressed air supplied from the compressed air supply source to the nozzle, and a part of the compressed air introduction passage,
It is formed by a tubular passage formed between an exhaust pipe that constitutes the exhaust passage on the catalyst downstream side and an outer peripheral pipe arranged on the outer peripheral portion of the exhaust pipe.
【0006】[0006]
【作用】本発明において、圧縮空気がノズルに導かれ、
軽油等の還元剤が触媒前面に噴霧される。従って、軽油
等の還元剤の霧化が促進され、その気化・混合性が向上
されて、軽油等の還元剤を触媒の前面にむらなく添加す
ることができる。そして、圧縮空気は、触媒下流側排気
通路を構成する排気管と、該排気管外周部に配設された
外周管との間に形成される筒状通路を通過することによ
り、触媒通過後の排気の熱により加温され、圧縮空気温
度が高くなり、排気温度の低下を防止できる。従って、
触媒の活性化を図れ、触媒のNOx低減能力の向上を図
れる。In the present invention, compressed air is introduced to the nozzle,
A reducing agent such as light oil is sprayed on the front surface of the catalyst. Therefore, atomization of the reducing agent such as light oil is promoted, the vaporization and mixing properties thereof are improved, and the reducing agent such as light oil can be uniformly added to the front surface of the catalyst. Then, the compressed air passes through the tubular passage formed between the exhaust pipe that constitutes the exhaust passage on the catalyst downstream side and the outer peripheral pipe arranged at the outer peripheral portion of the exhaust pipe, so that the compressed air after passing through the catalyst It is heated by the heat of the exhaust gas, the temperature of the compressed air rises, and the decrease of the exhaust gas temperature can be prevented. Therefore,
The catalyst can be activated and the NOx reduction ability of the catalyst can be improved.
【0007】[0007]
【実施例】以下、本発明の実施例を図面に基づいて説明
する。図1において、ディーゼルエンジンの排気通路を
構成する排気管1にはNOx浄化用の触媒2が介装され
る。触媒2の上流側の排気管1には、還元剤としての軽
油を添加するためのノズル3が配設されている。Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a catalyst 2 for purifying NOx is provided in an exhaust pipe 1 which constitutes an exhaust passage of a diesel engine. A nozzle 3 for adding light oil as a reducing agent is arranged in the exhaust pipe 1 on the upstream side of the catalyst 2.
【0008】このノズル3には、軽油供給管4が接続さ
れ、該軽油供給管4は軽油タンク5に連通される。又、
軽油供給管4には軽油噴射用ポンプ6が介装される。一
方、前記ノズル3に軽油噴霧用の圧縮空気を導入する圧
縮空気導入装置7が設けられている。この圧縮空気導入
装置7は、圧縮空気供給源としてのコンプレッサ8と、
該コンプレッサ8から供給される圧縮空気をノズル3に
導入する圧縮空気導入通路と、を含んで構成される。A light oil supply pipe 4 is connected to the nozzle 3, and the light oil supply pipe 4 communicates with a light oil tank 5. or,
A light oil injection pump 6 is interposed in the light oil supply pipe 4. On the other hand, the nozzle 3 is provided with a compressed air introduction device 7 for introducing compressed air for spraying light oil. The compressed air introduction device 7 includes a compressor 8 as a compressed air supply source,
And a compressed air introduction passage for introducing the compressed air supplied from the compressor 8 into the nozzle 3.
【0009】即ち、前記圧縮空気導入通路の一部を構成
する第1の空気導入管9には、上流から順に、フィルタ
10、コンプレッサ8、空気貯留用のバッファタンク1
1、開閉バルブ12が夫々介装される。尚、バッファタ
ンク11には圧力計13が設けられている。又、前記圧
縮空気導入通路の一部は、前記触媒2下流側の排気管1
と、該排気管1外周部に配設された外周管14との間に
形成される筒状通路15により形成され、この筒状通路
15には、前記第1の空気導入管9が連通接続される。That is, in the first air introducing pipe 9 forming a part of the compressed air introducing passage, the filter 10, the compressor 8 and the buffer tank 1 for storing air are arranged in this order from the upstream side.
1 and an on-off valve 12 are provided respectively. The buffer tank 11 is provided with a pressure gauge 13. Further, a part of the compressed air introducing passage is provided in the exhaust pipe 1 downstream of the catalyst 2.
And the outer peripheral pipe 14 disposed on the outer peripheral portion of the exhaust pipe 1 are formed by a cylindrical passage 15, and the first air introducing pipe 9 is connected to the cylindrical passage 15 for communication. To be done.
【0010】更に、この筒状通路15には、第2の空気
導入管16の一端部が連通接続され、該第2の空気導入
管16の他端部は前記ノズル3に連通接続される。前記
軽油噴射用ポンプ6と前記開閉バルブ12とは、夫々エ
ンジン運転状態に応じて制御され、軽油の添加時期と添
加量を適正に調整する。即ち、エンジン回転数を検出す
る回転数センサ17と、エンジン負荷(例えば、燃料噴
射ポンプのコントロールラック位置等)を検出する負荷
センサ18とが設けられると共に、前記軽油噴射用ポン
プ6を制御するポンプ用コントローラ19と、前記開閉
バルブ12を制御するバルブ用コントローラ20とが設
けられている。両コントローラ19,20には、夫々回
転数センサ17と負荷センサ18とから出力される検出
信号が入力され、両コントローラ19,20は、夫々エ
ンジン回転数と負荷とに基づいて、軽油噴射用ポンプ6
と開閉バルブ12とを夫々制御する。Further, one end of a second air introducing pipe 16 is connected to the cylindrical passage 15 and the other end of the second air introducing pipe 16 is connected to the nozzle 3. The light oil injection pump 6 and the opening / closing valve 12 are respectively controlled according to the engine operating state to properly adjust the addition timing and the addition amount of the light oil. That is, a rotation speed sensor 17 for detecting an engine speed and a load sensor 18 for detecting an engine load (for example, a control rack position of a fuel injection pump) are provided, and a pump for controlling the light oil injection pump 6 is provided. A controller 19 for valves and a valve controller 20 for controlling the on-off valve 12 are provided. The detection signals output from the rotation speed sensor 17 and the load sensor 18 are input to the controllers 19 and 20, respectively, and the controllers 19 and 20 detect the light oil injection pump based on the engine rotation speed and the load, respectively. 6
And the on-off valve 12 are controlled respectively.
【0011】図2は軽油の添加制御を説明するフローチ
ャートで、エンジンの始動により実行され、回転数セン
サ17と負荷センサ18の検出信号からエンジン回転数
と負荷とを読み取り、これらに対応する軽油添加量をデ
ータマップから求め、これらに相当するポンプ駆動電圧
とバルブの開動作又は閉動作でポンプ6と開閉バルブ1
2とを作動し、ノズル3から触媒2へ軽油を高圧噴射さ
せる(S1〜S4)。FIG. 2 is a flow chart for explaining the light oil addition control, which is executed when the engine is started, reads the engine speed and the load from the detection signals of the rotation speed sensor 17 and the load sensor 18, and adds the light oil corresponding thereto. The amount is obtained from the data map, and the pump 6 and the on-off valve 1 are operated by the pump driving voltage and the valve opening / closing operation corresponding to these values
2 are operated to inject light oil from the nozzle 3 to the catalyst 2 under high pressure (S1 to S4).
【0012】このような構成により、触媒2の還元剤と
しての軽油がノズル3から触媒2前面に添加される。
尚、軽油添加の最適量はエンジン運転状態に応じて必ず
しも比例的に増加させれば良いものではなく、エンジン
排気温度が所定値を越えると、触媒の過剰な高温化を抑
制するため、減少させることも必要となる。With such a configuration, light oil as a reducing agent for the catalyst 2 is added from the nozzle 3 to the front surface of the catalyst 2.
It should be noted that the optimum amount of light oil addition need not necessarily be proportionally increased in accordance with the engine operating state, and is decreased when the engine exhaust temperature exceeds a predetermined value to suppress excessive temperature rise of the catalyst. It is also necessary.
【0013】かかる構成によると、コンプレッサ8から
の圧縮空気は、第1の空気導入管9を通って、排気管1
と外周管14との間に形成される筒状通路15に至り、
この筒状通路15を通って、第2の空気導入管16に至
り、ノズル3へと導入される。従って、圧縮空気は、筒
状通路15を通る間に、触媒2を通過した排気の熱によ
り加温されてノズル3に導入されることになる。According to this structure, the compressed air from the compressor 8 passes through the first air introduction pipe 9 and the exhaust pipe 1
To the cylindrical passage 15 formed between the outer peripheral tube 14 and
Through the tubular passage 15, it reaches the second air introducing pipe 16 and is introduced into the nozzle 3. Therefore, the compressed air is heated by the heat of the exhaust gas that has passed through the catalyst 2 and is introduced into the nozzle 3 while passing through the tubular passage 15.
【0014】このため、ノズル3に導入される圧縮空気
温度が高くなり、排気温度の低下を防止でき、よって、
触媒2の活性化を図れ、触媒2のNOx低減能力の向上
を図れる。特に、排気熱の有効利用により圧縮空気を加
温しているため、空気加熱手段を別途設ける必要がな
く、排気管1に外周管14を付加するだけであるから、
構造の簡略化を図れ、コスト低減を図ることができる。Therefore, the temperature of the compressed air introduced into the nozzle 3 becomes high, and the exhaust temperature can be prevented from lowering.
The catalyst 2 can be activated and the NOx reduction ability of the catalyst 2 can be improved. In particular, since the compressed air is heated by effectively utilizing the exhaust heat, it is not necessary to separately provide an air heating means, and only the outer peripheral pipe 14 is added to the exhaust pipe 1,
The structure can be simplified and the cost can be reduced.
【0015】[0015]
【発明の効果】以上説明したように、本発明によれば、
圧縮空気供給源からの圧縮空気を、排気管と外周管との
間に形成される筒状通路を通過させて、ノズルへと導入
するようにしたから、圧縮空気を、筒状通路を通る間
に、触媒を通過した排気の熱により加温してノズルに導
入することができ、もって、排気温度の低下を防止で
き、触媒の活性化を図れ、触媒のNOx低減能力の向上
を図れる。As described above, according to the present invention,
Since the compressed air from the compressed air supply source is introduced into the nozzle by passing through the cylindrical passage formed between the exhaust pipe and the outer peripheral pipe, In addition, the heat of the exhaust gas that has passed through the catalyst can be heated and introduced into the nozzle, so that the exhaust gas temperature can be prevented from lowering, the catalyst can be activated, and the NOx reduction capability of the catalyst can be improved.
【0016】特に、排気熱の有効利用により圧縮空気を
加温しているため、空気加熱手段を別途設ける必要がな
く、構造の簡略化を図れ、コスト低減を図ることができ
る。In particular, since the compressed air is heated by effectively utilizing the exhaust heat, it is not necessary to separately provide an air heating means, the structure can be simplified, and the cost can be reduced.
【図1】 本発明の一実施例のシステム構成図FIG. 1 is a system configuration diagram of an embodiment of the present invention.
【図2】 同上実施例の作用を説明するフローチャートFIG. 2 is a flowchart for explaining the operation of the above embodiment.
1 排気管 2 触媒 3 ノズル 7 圧縮空気導入装置 8 コンプレッサ 9 第1の空気導入管 14 外周管 15 筒状通路 1 Exhaust Pipe 2 Catalyst 3 Nozzle 7 Compressed Air Introducing Device 8 Compressor 9 First Air Introducing Pipe 14 Outer Pipe 15 Cylindrical Passage
フロントページの続き (72)発明者 赤川 久 埼玉県上尾市大字壱丁目1番地 日産ディ ーゼル工業株式会社内Front Page Continuation (72) Inventor Hisashi Akagawa 1-chome, Io-chome, Ageo City, Saitama Prefecture Nissan Diesel Industry Co., Ltd.
Claims (1)
を、排気通路に介装された触媒で除去する排気浄化装置
において、 前記触媒の上流側の排気通路に還元剤を添加するための
ノズルと、 前記ノズルに還元剤噴霧用の圧縮空気を導入する圧縮空
気導入装置と、 を含んで構成され、 前記圧縮空気導入装置は、 圧縮空気供給源と、該圧縮空気供給源から供給される圧
縮空気をノズルに導入する圧縮空気導入通路と、を含ん
で構成され、 前記圧縮空気導入通路の一部は、前記触媒下流側排気通
路を構成する排気管と、該排気管外周部に配設された外
周管との間に形成される筒状通路により形成されたこと
を特徴とするエンジンの排気浄化装置。1. An exhaust emission control device for removing nitrogen oxides contained in exhaust gas of an engine with a catalyst interposed in an exhaust passage, wherein a nozzle for adding a reducing agent to an exhaust passage upstream of the catalyst. And a compressed air introducing device for introducing compressed air for spraying a reducing agent to the nozzle, wherein the compressed air introducing device is a compressed air supply source and a compressed air supplied from the compressed air supply source. A compressed air introduction passage for introducing air into the nozzle is included, and a part of the compressed air introduction passage is arranged in an exhaust pipe constituting the catalyst downstream side exhaust passage and an outer peripheral portion of the exhaust pipe. An exhaust gas purifying apparatus for an engine, which is formed by a cylindrical passage formed between the outer peripheral pipe and the outer peripheral pipe.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP712495A JPH08200046A (en) | 1995-01-20 | 1995-01-20 | Exhaust emission control device for engine |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP712495A JPH08200046A (en) | 1995-01-20 | 1995-01-20 | Exhaust emission control device for engine |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH08200046A true JPH08200046A (en) | 1996-08-06 |
Family
ID=11657336
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP712495A Pending JPH08200046A (en) | 1995-01-20 | 1995-01-20 | Exhaust emission control device for engine |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH08200046A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009074533A (en) * | 2007-08-15 | 2009-04-09 | Kubota Corp | Exhaust system for diesel engine |
-
1995
- 1995-01-20 JP JP712495A patent/JPH08200046A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009074533A (en) * | 2007-08-15 | 2009-04-09 | Kubota Corp | Exhaust system for diesel engine |
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