JP4289574B2

JP4289574B2 - Nitrogen oxide purification equipment

Info

Publication number: JP4289574B2
Application number: JP24952299A
Authority: JP
Inventors: 田公信平
Original assignee: UD Trucks Corp
Current assignee: UD Trucks Corp
Priority date: 1999-09-03
Filing date: 1999-09-03
Publication date: 2009-07-01
Anticipated expiration: 2019-09-03
Also published as: JP2001073744A

Description

【０００１】
【発明の属する技術分野】
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等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装する窒素酸化物（以下窒素酸化物をＮＯｘと記す）浄化装置に関する。
【０００２】
【従来の技術】
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ように酸素過剰雰囲気の排気ガスを排出する内燃機関においては、従来、三元触媒を用いてＮＯｘを効果的に浄化することは困難であった。
三元触媒におけるＮＯｘの浄化は、排気ガス中の還元成分（例えばＨＣ）によってＮＯｘの還元反応が行われるものであるが、しかしながら、酸素過剰雰囲気下においては、還元成分と雰囲気中の酸素が反応するので、ＮＯｘの還元反応が阻害されるという問題が存在する。
【０００３】
そこで、ディーゼルエンジンにあっては、図９に示すようにエンジン１に接続された排気系２に三元触媒５を介装し、軽油添加装置６を設けてその触媒５の上流に設けたノズル８から排気ガスＥ中に還元剤として軽油を添加する技術が提案されている。しかし、図９の従来技術では、還元剤が過剰な酸素と反応し、ＮＯｘの還元作用が充分に行われないという問題点を有している。
なお、図中、符号７は軽油添加装置６に軽油を供給する燃料タンク、１５Ａはこれらを制御する制御装置、１６はエンジン１の運転状態を検出し制御装置１５Ａに伝えるセンサをそれぞれ示している。
【０００４】
また、本出願人は、特願平６−２０５６４０号に、ポンプで還元剤を加圧して蓄圧室に貯留し、触媒上流の排気ガス中に噴射する技術を提案している。
この他、特開平９−８５０４９号公報、特開平９−３１７４４３号公報等に排気ガス浄化装置が示されているが、いずれも還元剤が過剰な酸素と反応し、そのため効率よくＮＯｘを還元できるものではない。
【０００５】
【発明が解決しようとする課題】
本発明は上記の従来技術の問題点に対して提案されたもので、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等の酸素過剰雰囲気の排気ガスを排出する内燃機関において、ＮＯｘを効率よく浄化することができるＮＯｘ浄化装置を提供することを目的としている。
【０００６】
【課題を解決するための手段】
出願人は、特に、酸素過剰雰囲気下において、ＮＯｘの還元反応が進行するために必要な中間生成物（後記する）を排気ガス中に積極的に生成させれば、上記した問題点（過剰の酸素が還元剤と反応してＮＯｘの還元が阻害される）を解消できることに着目した。
【０００７】
本発明の窒素酸化物浄化装置は、酸素過剰雰囲気の排気ガス（Ｅ）を排出するエンジン（１）の排気系（２）で窒素酸化物（ＮＯｘ）を浄化する窒素酸化物浄化装置において、前記エンジン（１）に接続された排気系（２）にＮＯｘ浄化用触媒（５）が介装され、前記排気ガス（Ｅ）中にオゾンおよび還元剤をそれぞれ供給するためのオゾン供給手段（１０）および還元剤供給手段（２０）が設けられ、前記オゾン供給手段（１０）はオゾン発生装置（１２）と、そのオゾン発生装置（１２）に大気（Ａ）を供給するエアポンプ（１１）とで構成され、そのオゾン発生装置（１２）は燃料タンク（７）に連通されてオゾンが還元剤中にバブリングして溶解するように構成され、前記還元剤供給手段（２０）は前記燃料タンク（７）と、燃料タンク（７）と連通して排気系（２）に軽油を供給する軽油添加装置（６）と、その軽油添加装置（６）に連通して排気系（２）にオゾンおよび還元剤として軽油を供給する還元剤添加ノズル（８）とで構成され、前記エンジン（１）にエンジン（１）の運転状態を検出するセンサ（１６）が設けられ、前記ＮＯｘ浄化用触媒（５）の入口に触媒温度センサ（３）が設けられ、そのセンサ（１６）および触媒温度センサ（３）の信号に基いてオゾン供給手段（１０）および軽油添加装置（６）を制御する制御装置（１５）が設けられており、その制御装置（１５）は前記センサ（１６）からエンジン運転状態のデータおよび温度センサ（３）からＮＯｘ浄化用触媒（５）入口温度を読み込み（ステップＳ１）、ＮＯｘ浄化用触媒（５）温度の判定を行い（ステップＳ２）、ＮＯｘ浄化用触媒（５）がＮＯｘ浄化機能を行うのに適正な範囲内であればオゾン発生装置（１２）、エアポンプ（１１）および還元剤供給手段（２０）の軽油添加装置（６）を制御する（ステップＳ３）機能を有している。
【０００８】
また本発明によれば、酸素過剰雰囲気の排気ガス（Ｅ）を排出するエンジン（１）の排気系（２）で窒素酸化物（ＮＯｘ）を浄化する窒素酸化物浄化装置において、前記エンジン（１）に接続された排気系（２）にＮＯｘ浄化用触媒（５）が介装され、前記排気ガス（Ｅ）中にオゾンおよび還元剤をそれぞれ供給するためのオゾン供給手段（１０）および還元剤供給手段（２０）が設けられ、前記オゾン供給手段（１０）はオゾン発生装置（１２）と、そのオゾン発生装置（１２）に大気（Ａ）を供給するエアポンプ（１１）とで構成され、そのオゾン発生装置（１２）は燃料タンク（７）に連通されてオゾンが軽油中にバブリングするよう構成され、前記還元剤供給手段（２０）は燃料タンク（７）と、燃料タンク（７）に接続されてエンジン（１）に設けられた蓄圧式燃料噴射装置（４）とで構成され、前記エンジン（１）にエンジン（１）の運転状態を検出するセンサ（１６）が設けられ、前記ＮＯｘ浄化用触媒（５）の入口に触媒温度センサ（３）が設けられ、前記センサ（１６）および触媒温度センサ（３）の信号に基いてオゾン供給手段（１０）および前記還元剤供給手段（２０）の蓄圧式燃料噴射装置（４）を制御する制御装置（１５）が設けられており、その制御装置（１５）は前記センサ（１６）からエンジン運転状態のデータおよび温度センサ（３）からＮＯｘ浄化用触媒（５）入口温度を読み込み（ステップＳ１）、ＮＯｘ浄化用触媒（５）温度の判定を行い（ステップＳ２）、ＮＯｘ浄化用触媒（５）がＮＯｘ浄化機能を行うのに適正な範囲内であればオゾン発生装置（１２）、エアポンプ（１１）および前記還元剤供給手段（２０）の蓄圧式燃料噴射装置（４）を制御する（ステップＳ３）機能を有している。
【００１０】
前記オゾン供給手段から供給される添加剤は、窒素酸化物の還元に必要な中間体の生成を促すものであれば、気体、液体、固体のいずれでも良いが、オゾンであるのが好ましい。この場合は、オゾン供給手段（窒素酸化物の還元に必要な中間体の生成を促す添加剤を供給する供給手段）は、いわゆるオゾナイザ（オゾン発生装置）を用いても良いし、あるいは、オゾンを貯留したボンベ等を用いても良い。
【００１１】
ここで、前記窒素酸化物の還元に必要な中間体の生成を促す添加剤を供給する添加手段と還元剤添加手段とは、ＮＯｘ浄化用触媒の上流であれば、そのどちらを上流側としてもよい。
【００１２】
また、前記窒素酸化物の還元に必要な中間体の生成を促す添加剤を供給する添加手段がオゾン発生装置である場合には、還元剤添加手段は、オゾン発生装置を通過したオゾンを含む空気によって還元剤を排気ガス中に（例えば、エジェクタ等を用い）添加するものであってもよい。
【００１３】
前記還元剤添加手段としては、エンジンシリンダ内に燃料を噴射するもの、例えば、いわゆる「コモンレール式噴射装置」を用いてもよい。
【００１４】
ＮＯｘの還元作用は、下記［化学反応式］に示すように、ＮＯ_２、ＮＯ_３ ⁻、ＣＨ_３ＣＯＯ⁻、ＨＣＯＯ⁻、−ＮＣＯ、−ＣＮ等の中間生成物を経てＮ_２、ＣＯ_２、Ｈ_２Ｏに還元される。
なお、下記［化学反応式］に示すＣ_３Ｈ_６は、還元剤としてのＨＣを代表して示したものである。

【００１５】
本発明によれば、オゾンのような「窒素酸化物の還元に必要な中間体の生成を促す添加剤」が排気系に供給されるので、上記［化学反応式］に示す中間生成物の生成が促進される。そのため、還元剤が過剰な酸素と反応してＮＯｘの還元が阻害されることなく、ＮＯｘが確実に還元され、排気ガスからＮＯｘが除去される。これにより、排気ガス浄化の効率を向上させることができる。
【００１６】
なお、添加手段および還元剤添加手段によってＮＯｘ浄化用触媒の上流に添加されるオゾンおよび還元剤の添加量が、運転状態を検出し制御装置で正確に制御されるように構成すれば、オゾン（あるいは、窒素酸化物の還元に必要な中間体の生成を促す添加剤）および還元剤（例えば、軽油）の使用量を節約してより効率的な運転が可能となる。
【００１７】
【発明の実施の形態】
以下、図面を参照して本発明について説明する。
参考例を示す図１において、エンジン１に接続された排気系２にはＮＯｘ浄化用触媒５が介装されており、また、排気ガスＥ中に（窒素酸化物の還元に必要な中間体の生成を促す添加剤、例えば）オゾンおよび還元剤をそれぞれ供給するオゾン供給手段１０および還元剤供給手段２０（例えば、後記する軽油添加装置６および還元剤添加ノズル）が設けられている。
【００１８】
そのオゾン供給手段１０は、オゾン発生装置１２と、その発生装置１２に大気Ａを供給するエアポンプ１１と、発生装置１２と連通されて前記触媒５の上流の排気系２にオゾンを添加するオゾン添加ノズル１３とで構成されている。また、還元剤供給手段２０は、燃料タンク７と連通されて軽油が供給される軽油添加装置６と、その軽油添加装置６に連通され前記触媒５の上流の排気系２に還元剤として軽油を添加する還元剤添加ノズル８とで構成されている。
【００１９】
そして、センサ１６の検出するエンジンの運転状態、および触媒温度センサ３の信号に基いて、オゾン供給手段および還元剤供給手段２０を制御する制御装置１５が設けられ、オゾン発生装置１２、エアポンプ１１、および図示しない軽油添加装置６に配線されている。
【００２０】
上記参考例によれば、エアポンプ１１でオゾン発生装置１２（窒素酸化物の還元に必要な中間体の生成を促す添加剤を供給する添加手段）に大気Ａが供給され、オゾン発生装置１２で発生したオゾンを含む空気がオゾン添加ノズル１３から排気系２の排気ガスＥ中に添加され、同時に燃料タンク７から供給された軽油が軽油添加装置６により還元剤添加ノズル８から排気ガスＥ中に添加される。そして、制御装置１５によってエンジン運転状態および触媒温度に基づいてエアポンプ１１、オゾン発生装置１２および軽油添加装置６が制御され、オゾンおよび還元剤の添加量が調整されている。したがって、触媒５におけるＮＯｘ還元作用の中間生成物（ＮＯ_２、ＮＯ_３ ⁻ 、ＣＨ_３ＣＯＯ⁻ 、ＨＣＯＯ⁻ 、−ＮＣＯ、−ＣＮ等）の生成が促進され、ＮＯｘ浄化の効率を向上させることができる。
【００２１】
また、図２には、本発明の他の参考例が示されている。図２において、排気系２のＮＯｘ浄化用触媒５の上流には、オゾン添加ノズル１３Ａが設けられ、そのオゾン添加ノズル１３Ａは、オゾン発生装置１２および軽油添加装置６から連通され、オゾンおよび還元剤（軽油）が混合されて排気ガス中に供給されている。そのため、還元剤である軽油は、オゾン発生装置１２で発生するオゾンを大量に含んだ空気によりノズル１３Ａから噴射されている。その他は前記図１と同様に構成されている。
【００２２】
図３に示す本発明の第１の実施形態では、オゾン発生装置１２で発生されたオゾンは、燃料タンク７に導かれて還元剤（軽油）中にバブリングされている。したがって、オゾンは還元剤中に溶解され、軽油添加装置６によって還元剤添加ノズル８から排気系２に添加されている。
【００２３】
図４に示す参考例では、オゾン発生装置１２で発生されたオゾンは、吸気管１ａに導かれ、オゾン添加ノズル１３Ａから噴射されて吸気Ａに添加されている。また、軽油添加装置６からは、ノズル８によって排気系２に還元剤が添加されている。こうして、オゾンは吸気管１ａで吸気Ａに添加されて、さらに排気系２へ、また、還元剤は直接排気ガスＥ中に添加されて共に触媒５に供給されている。
【００２４】
図５〜図７には、蓄圧式（いわゆるコモンレール式）燃料噴射装置４を用いて触媒５に還元剤として未燃燃料を（例えば、排気行程期間に噴射、あるいは排気管に直接）供給する方式が示されている。
図５に示す本発明の第２の実施形態は、オゾン発生装置１２で発生させたオゾンを燃料タンク７に導き、バブリングによって軽油中に溶解させ、燃料噴射装置４からオゾンおよび還元剤として未燃燃料が触媒５に供給されている。
図６に示す参考例では、燃料噴射装置４から還元剤として未燃燃料が触媒５に供給され、オゾンは、オゾン発生装置１２からノズル１３によって排気系２に添加されている。さらに、図７に示す参考例は、燃料噴射装置４から還元剤として未燃燃料を触媒５に供給、オゾンは、オゾン発生装置１２からノズル１３Ａにより吸気管１ａに供給されている。
【００２５】
次に図８を参照し、これらオゾン供給手段及び還元剤供給手段の制御の一実施形態を説明する。スタートして、まず、ステップＳ１にてセンサ１６からエンジン運転状態のデータ、および温度センサから触媒入口温度を読み込む。そして、ステップＳ２にて、触媒温度の判定を行う。触媒５がＮＯｘ浄化機能を行うのに適正な範囲外であればステップＳ１に戻る。一方、触媒がＮＯｘ浄化機能を行うのに適正な範囲内であれば、ステップＳ３に進み、オゾン発生装置１２、エアポンプ１１および還元剤添加装置２０の制御を行う。すなわち、オゾンおよび軽油の適正添加量を決定し、その添加量になるようにオゾン発生装置１２、ポンプ１１、還元剤添加装置２０を制御する。そして、ステップＳ１に戻る。
【００２６】
【発明の効果】
本発明は、以上説明したように構成され、以下の優れた効果を奏する。
（１）ＮＯｘ浄化反応の進行に必要な中間生成物の生成により、ＮＯｘ浄化の効率を向上させることができる。
（２）オゾン添加は還元剤の反応性を向上させるので、未反応のまま放出されていた還元剤成分を減少させることができる。
【図面の簡単な説明】
【図１】本発明の参考例を示す構成図。
【図２】本発明の他の参考例を示す構成図。
【図３】本発明の第１の実施形態を示す構成図。
【図４】本発明の他の参考例を示す構成図。
【図５】本発明の第２の実施形態を示す構成図。
【図６】本発明の他の参考例を示す構成図。
【図７】本発明の他の参考例を示す構成図。
【図８】本発明の制御を示すフローチャート図。
【図９】従来のＮＯｘ浄化装置を示す構成図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nitrogen oxide (hereinafter referred to as NOx) purifying device interposed 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.
[0002]
[Prior art]
In an internal combustion engine that exhausts exhaust gas in an oxygen-excess atmosphere such as a diesel engine or a lean burn gasoline engine, it has been difficult to effectively purify NOx using a three-way catalyst.
NOx purification in a three-way catalyst is a reduction reaction of NOx by a reducing component (for example, HC) in exhaust gas. However, in an oxygen-excess atmosphere, the reducing component reacts with oxygen in the atmosphere. Therefore, there is a problem that the reduction reaction of NOx is inhibited.
[0003]
Therefore, in a diesel engine, as shown in FIG. 9, a three-way catalyst 5 is interposed in an exhaust system 2 connected to the engine 1, a light oil addition device 6 is provided, and a nozzle provided upstream of the catalyst 5. 8 has proposed a technique of adding light oil as a reducing agent to the exhaust gas E. However, the prior art shown in FIG. 9 has a problem that the reducing agent reacts with excess oxygen, and NOx is not sufficiently reduced.
In the figure, reference numeral 7 denotes a fuel tank that supplies light oil to the light oil adding device 6, 15A denotes a control device that controls them, and 16 denotes a sensor that detects the operating state of the engine 1 and transmits it to the control device 15A. .
[0004]
Further, the present applicant has proposed in Japanese Patent Application No. 6-205640 a technique in which a reducing agent is pressurized with a pump, stored in a pressure accumulating chamber, and injected into exhaust gas upstream of the catalyst.
In addition, although an exhaust gas purifying device is shown in JP-A-9-85049, JP-A-9-317443, etc., in all cases, the reducing agent reacts with excess oxygen, so that NOx can be reduced efficiently. It is not a thing.
[0005]
[Problems to be solved by the invention]
The present invention has been proposed to solve the above-mentioned problems of the prior art, and can effectively purify NOx in an internal combustion engine that exhausts exhaust gas in an oxygen-excess atmosphere such as a diesel engine or a lean burn gasoline engine. The object is to provide a NOx purification device.
[0006]
[Means for Solving the Problems]
In particular, if the applicant actively produces an intermediate product (described later) required for the NOx reduction reaction in an oxygen-excess atmosphere, We focused on the fact that oxygen reacts with the reducing agent to prevent NOx reduction).
[0007]
The nitrogen oxide purifying apparatus of the present invention is the nitrogen oxide purifying apparatus that purifies nitrogen oxide (NOx) by the exhaust system (2) of the engine (1) that exhausts the exhaust gas (E) in an oxygen-excess atmosphere. An NOx purification catalyst (5) is interposed in the exhaust system (2) connected to the engine (1), and ozone supply means (10) for supplying ozone and a reducing agent to the exhaust gas (E), respectively. And the reducing agent supply means (20). The ozone supply means (10) includes an ozone generator (12) and an air pump (11) that supplies the atmosphere (A) to the ozone generator (12). The ozone generator (12) communicates with the fuel tank (7) so that ozone is bubbled and dissolved in the reducing agent, and the reducing agent supply means (20) includes the fuel tank (7). And fuel A diesel oil addition device (6) for supplying diesel oil to the exhaust system (2) in communication with the gas (7), and ozone and a diesel oil as a reducing agent to the exhaust system (2) in communication with the diesel oil addition device (6). A reducing agent addition nozzle (8) to be supplied, a sensor (16) for detecting an operating state of the engine (1) is provided in the engine (1), and a catalyst is provided at an inlet of the NOx purification catalyst (5). A temperature sensor (3) is provided, and a control device (15) for controlling the ozone supply means (10) and the light oil addition device (6) based on signals from the sensor (16) and the catalyst temperature sensor (3) is provided. The controller (15) reads the engine operating state data from the sensor (16) and the NOx purification catalyst (5) inlet temperature from the temperature sensor (3) (step S1), and the NOx purification catalyst (5). ) Temperature format (Step S2), and if the NOx purification catalyst (5) is within an appropriate range for performing the NOx purification function, the light oil of the ozone generator (12), the air pump (11), and the reducing agent supply means (20) It has a function of controlling the adding device (6) (step S3).
[0008]
According to the present invention, in the nitrogen oxide purifying apparatus for purifying nitrogen oxide (NOx) by the exhaust system (2) of the engine (1) that exhausts the exhaust gas (E) in an oxygen-excess atmosphere, the engine (1) The NOx purification catalyst (5) is interposed in the exhaust system (2) connected to the exhaust gas (E), and the ozone supply means (10) and the reducing agent for supplying ozone and the reducing agent to the exhaust gas (E), respectively. A supply means (20) is provided, and the ozone supply means (10) comprises an ozone generator (12) and an air pump (11) for supplying the atmosphere (A) to the ozone generator (12), The ozone generator (12) is connected to the fuel tank (7) so that ozone is bubbled into the light oil, and the reducing agent supply means (20) is connected to the fuel tank (7) and the fuel tank (7). Being en And an accumulator fuel injection device (4) provided in the engine (1), the engine (1) is provided with a sensor (16) for detecting the operating state of the engine (1), and the NOx purification catalyst A catalyst temperature sensor (3) is provided at the inlet of (5), and the accumulated pressure of the ozone supply means (10) and the reducing agent supply means (20) is based on the signals of the sensor (16) and the catalyst temperature sensor (3). A control device (15) for controlling the fuel injection device (4) is provided. The control device (15) receives the engine operating state data from the sensor (16) and the NOx purification catalyst from the temperature sensor (3). (5) The inlet temperature is read (step S1), the temperature of the NOx purification catalyst (5) is determined (step S2), and the NOx purification catalyst (5) is within an appropriate range for performing the NOx purification function. If Emissions generator (12), controls the air pump (11) and the accumulator fuel injection system of the reducing agent supply means (20) (4) has a (step S3) function.
[0010]
The additive supplied from the ozone supply means may be any of gas, liquid, and solid as long as it promotes the generation of an intermediate necessary for the reduction of nitrogen oxides, but is preferably ozone. In this case, the ozone supply means (supply means for supplying an additive that promotes the generation of an intermediate necessary for the reduction of nitrogen oxides) may be a so-called ozonizer (ozone generator), or ozone may be used. A stored cylinder or the like may be used.
[0011]
Here, the adding means for supplying the additive that promotes the generation of the intermediate necessary for the reduction of the nitrogen oxide and the reducing agent adding means are upstream of the NOx purification catalyst, and either of them may be the upstream side. Good.
[0012]
In addition, when the adding means for supplying the additive that promotes the generation of the intermediate necessary for the reduction of the nitrogen oxide is an ozone generator, the reducing agent adding means is an air containing ozone that has passed through the ozone generator. The reducing agent may be added to the exhaust gas (for example, using an ejector or the like).
[0013]
As the reducing agent adding means, a means for injecting fuel into the engine cylinder, for example, a so-called “common rail type injection device” may be used.
[0014]
As shown in the following [chemical reaction formula], the reduction action of NOx is caused by N ₂ , CO ₂ , NO ₂ , NO ₃ ⁻ , CH ₃ COO ⁻ , HCOO ⁻ , —NCO, —CN and the like through intermediate products. Reduced to H ₂ O.
In addition, C ₃ H ₆ shown in the following [chemical reaction formula] is representative of HC as a reducing agent.

[0015]
According to the present invention, since an “additive that promotes the generation of an intermediate necessary for the reduction of nitrogen oxides” such as ozone is supplied to the exhaust system, the intermediate product shown in the above [chemical reaction formula] is generated. Is promoted. Therefore, the NOx is reliably reduced and NOx is removed from the exhaust gas without the reducing agent reacting with excess oxygen and inhibiting the reduction of NOx. Thereby, the efficiency of exhaust gas purification can be improved.
[0016]
If the addition means and the addition amount of the reducing agent addition means and the addition amount of the reducing agent upstream of the NOx purification catalyst are configured so that the operating state is detected and accurately controlled by the control device, ozone ( Alternatively, more efficient operation can be achieved by saving the amount of additives used to generate intermediates necessary for the reduction of nitrogen oxides) and reducing agents (for example, light oil).
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
In FIG. 1 showing a reference example, a NOx purification catalyst 5 is interposed in an exhaust system 2 connected to the engine 1, and in the exhaust gas E (an intermediate necessary for the reduction of nitrogen oxides). There are provided an ozone supplying means 10 and a reducing agent supplying means 20 (for example, a light oil adding device 6 and a reducing agent adding nozzle, which will be described later) for supplying an additive for promoting production, for example, ozone and a reducing agent, respectively.
[0018]
The ozone supply means 10 includes an ozone generator 12, an air pump 11 that supplies air A to the generator 12, and an ozone addition that communicates with the generator 12 and adds ozone to the exhaust system 2 upstream of the catalyst 5. It consists of a nozzle 13. Further, the reducing agent supply means 20 is connected to the fuel tank 7 to supply light oil, and the light oil adding device 6 is connected to the light oil adding device 6 and is connected to the exhaust system 2 upstream of the catalyst 5 to supply light oil as a reducing agent. It is comprised with the reducing agent addition nozzle 8 to add.
[0019]
A control device 15 for controlling the ozone supply means and the reducing agent supply means 20 is provided based on the operating state of the engine detected by the sensor 16 and the signal of the catalyst temperature sensor 3, and the ozone generator 12, the air pump 11, And it is wired to the light oil adding device 6 (not shown).
[0020]
According to the above reference example, the atmosphere A is supplied to the ozone generator 12 (adding means for supplying an additive that promotes the generation of an intermediate necessary for the reduction of nitrogen oxides) by the air pump 11 and is generated by the ozone generator 12. The ozone-containing air is added to the exhaust gas E of the exhaust system 2 from the ozone addition nozzle 13, and at the same time, the light oil supplied from the fuel tank 7 is added to the exhaust gas E from the reducing agent addition nozzle 8 by the light oil addition device 6. Is done. The control device 15 controls the air pump 11, the ozone generator 12, and the light oil addition device 6 based on the engine operating state and the catalyst temperature, and adjusts the addition amounts of ozone and the reducing agent. Therefore, the intermediate product (NO ₂ of NOx reduction action in the catalyst 5). , NO ₃ ⁻ , CH ₃ COO ⁻ , HCOO ⁻ , -NCO, -CN, etc.) are promoted, and the efficiency of NOx purification can be improved.
[0021]
FIG. 2 shows another reference example of the present invention. In FIG. 2, an ozone addition nozzle 13A is provided upstream of the NOx purification catalyst 5 in the exhaust system 2, and the ozone addition nozzle 13A communicates with the ozone generator 12 and the light oil addition device 6 so that ozone and a reducing agent are connected. (Light oil) is mixed and supplied into the exhaust gas. Therefore, the light oil as the reducing agent is injected from the nozzle 13 </ b> A by air containing a large amount of ozone generated by the ozone generator 12. The rest of the configuration is the same as in FIG.
[0022]
In the first embodiment of the present invention shown in FIG. 3, the ozone generated by the ozone generator 12 is guided to the fuel tank 7 and bubbled into the reducing agent (light oil). Therefore, ozone is dissolved in the reducing agent and added to the exhaust system 2 from the reducing agent addition nozzle 8 by the light oil addition device 6.
[0023]
In the reference example shown in FIG. 4, the ozone generated by the ozone generator 12 is guided to the intake pipe 1a, injected from the ozone addition nozzle 13A, and added to the intake air A. In addition, a reducing agent is added to the exhaust system 2 from the light oil adding device 6 by the nozzle 8. Thus, ozone is added to the intake air A through the intake pipe 1a, and further to the exhaust system 2, and the reducing agent is directly added to the exhaust gas E and supplied to the catalyst 5.
[0024]
5 to 7 show a method of supplying unburned fuel as a reducing agent to the catalyst 5 using a pressure accumulation type (so-called common rail type) fuel injection device 4 (for example, injection during the exhaust stroke period or directly to the exhaust pipe). It is shown.
In the second embodiment of the present invention shown in FIG. 5, the ozone generated by the ozone generator 12 is guided to the fuel tank 7, dissolved in light oil by bubbling, and unburned from the fuel injector 4 as ozone and a reducing agent. Fuel is supplied to the catalyst 5.
In the reference example shown in FIG. 6, unburned fuel is supplied as a reducing agent from the fuel injection device 4 to the catalyst 5, and ozone is added to the exhaust system 2 from the ozone generator 12 by the nozzle 13. Further, in the reference example shown in FIG. 7, unburned fuel is supplied as a reducing agent from the fuel injection device 4 to the catalyst 5, and ozone is supplied from the ozone generator 12 to the intake pipe 1a through the nozzle 13A.
[0025]
Next, an embodiment of control of the ozone supply means and the reducing agent supply means will be described with reference to FIG. First, in step S1, the engine operating state data is read from the sensor 16 and the catalyst inlet temperature is read from the temperature sensor. In step S2, the catalyst temperature is determined. If the catalyst 5 is outside the proper range for performing the NOx purification function, the process returns to step S1. On the other hand, if the catalyst is within an appropriate range for performing the NOx purification function, the process proceeds to step S3, where the ozone generator 12, the air pump 11, and the reducing agent addition device 20 are controlled. That is, the appropriate addition amount of ozone and light oil is determined, and the ozone generator 12, the pump 11, and the reducing agent addition device 20 are controlled so as to be the addition amount. Then, the process returns to step S1.
[0026]
【The invention's effect】
The present invention is configured as described above and has the following excellent effects.
(1) The efficiency of NOx purification can be improved by generating intermediate products necessary for the progress of the NOx purification reaction.
(2) Since the addition of ozone improves the reactivity of the reducing agent, it is possible to reduce the reducing agent component that has been released without being reacted.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a reference example of the present invention.
FIG. 2 is a configuration diagram showing another reference example of the present invention.
FIG. 3 is a configuration diagram showing a first embodiment of the present invention.
FIG. 4 is a configuration diagram showing another reference example of the present invention.
FIG. 5 is a configuration diagram showing a second embodiment of the present invention.
FIG. 6 is a configuration diagram showing another reference example of the present invention.
FIG. 7 is a configuration diagram showing another reference example of the present invention.
FIG. 8 is a flowchart showing the control of the present invention.
FIG. 9 is a configuration diagram showing a conventional NOx purification device.

Claims

In a nitrogen oxide purifying apparatus for purifying nitrogen oxide (NOx) by an exhaust system (2) of an engine (1) that exhausts exhaust gas (E) in an excess oxygen atmosphere, the exhaust system connected to the engine (1) (2) a catalyst for NOx purification (5) is interposed, the exhaust gas (E) the ozone supplying means for supplying ozone and the reducing agent respectively in (10) and a reducing agent supply means (20) is provided The ozone supply means (10) includes an ozone generator (12) and an air pump (11) for supplying the atmosphere (A) to the ozone generator (12). The ozone generator (12) The reductant supply means (20) communicates with the fuel tank (7) and the fuel tank (7). The reductant supply means (20) communicates with the fuel tank (7). Exhaust system (2 A diesel oil addition device (6) for supplying diesel oil to the exhaust gas, and a reducing agent addition nozzle (8) for communicating with the diesel oil addition device (6) and supplying diesel oil to the exhaust system (2) as ozone and a reducing agent. The engine (1) is provided with a sensor (16) for detecting the operating state of the engine (1), and a catalyst temperature sensor (3) is provided at the inlet of the NOx purification catalyst (5). ) And a catalyst temperature sensor (3), a control device (15) for controlling the ozone supply means (10) and the light oil addition device (6) is provided. 16) The engine operating state data and the temperature sensor (3) are read from the NOx purification catalyst (5) inlet temperature (step S1), and the NOx purification catalyst (5) temperature is determined (step S2). If the purification catalyst (5) is within an appropriate range for performing the NOx purification function, the ozone generator (12), the air pump (11), and the light oil addition device (6) of the reducing agent supply means (20) are controlled. (Step S3) A nitrogen oxide purifier having a function.

In a nitrogen oxide purification apparatus that purifies nitrogen oxides (NOx) by an exhaust system (2) of an engine (1) that exhausts exhaust gas (E) in an oxygen-excess atmosphere,
An NOx purification catalyst (5) is interposed in an exhaust system (2) connected to the engine (1), and ozone supply means (10) for supplying ozone and a reducing agent to the exhaust gas (E), respectively. ) And a reducing agent supply means (20). The ozone supply means (10) includes an ozone generator (12) and an air pump (11) that supplies the atmosphere (A) to the ozone generator (12). The ozone generator (12) is configured to communicate with the fuel tank (7) so that ozone is bubbled into the light oil. The reducing agent supply means (20) includes the fuel tank (7), the fuel tank ( 7) and an accumulator fuel injection device (4) provided in the engine (1), and the engine (1) is provided with a sensor (16) for detecting the operating state of the engine (1). , NO A catalyst temperature sensor (3) is provided at the inlet of the purification catalyst (5), and the ozone supply means (10) and the reducing agent supply means (20) based on signals from the sensor (16) and the catalyst temperature sensor (3). ) Of the accumulator fuel injection device (4) is provided, and the control device (15) is provided with the engine operation state data from the sensor (16) and the NOx from the temperature sensor (3). The inlet temperature of the purification catalyst (5) is read (step S1), the temperature of the NOx purification catalyst (5) is determined (step S2), and the NOx purification catalyst (5) is in an appropriate range for performing the NOx purification function. If inside, it has the function to control the pressure generating fuel injection device (4) of the ozone generator (12), the air pump (11) and the reducing agent supply means (20) (step S3). Nitrogen oxide purification equipment that.