JP2005113687A - Engine exhaust emission control device - Google Patents

Engine exhaust emission control device Download PDF

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JP2005113687A
JP2005113687A JP2003344757A JP2003344757A JP2005113687A JP 2005113687 A JP2005113687 A JP 2005113687A JP 2003344757 A JP2003344757 A JP 2003344757A JP 2003344757 A JP2003344757 A JP 2003344757A JP 2005113687 A JP2005113687 A JP 2005113687A
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injection nozzle
exhaust
reducing agent
supply
nozzle
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JP3732493B2 (en
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Hiroki Ueno
弘樹 上野
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UD Trucks Corp
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UD Trucks Corp
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Priority to JP2003344757A priority Critical patent/JP3732493B2/en
Application filed by UD Trucks Corp filed Critical UD Trucks Corp
Priority to EP04772987A priority patent/EP1672191B1/en
Priority to PCT/JP2004/013305 priority patent/WO2005033482A1/en
Priority to ES04772987T priority patent/ES2367485T3/en
Priority to US10/574,341 priority patent/US7703276B2/en
Priority to AT04772987T priority patent/ATE520868T1/en
Priority to CNB2004800286338A priority patent/CN100404808C/en
Priority to CN2008101106559A priority patent/CN101328827B/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To improve NOx emission control efficiency by eliminating choking in an injection nozzle to supply a reducing agent to the exhaust upstream side of a reduction catalyst when it occurs. <P>SOLUTION: In a reducing agent supply device 6, a detection signal for inner pressure of the injection nozzle 5 detected by a pressure sensor 15 is used to determine that the injection nozzle 5 has choking when the detected pressure becomes a prescribed value or more. Supply of compression air and urea water to the injection nozzle 5 is stopped to restrict cooling in a nozzle. Using a detection signal of exhaust temperature from an exhaust temperature sensor 9, it is determined that urea in the nozzle is melted when exhaust temperature close to the injection nozzle 5 becomes a fusing point or more of urea water, and supply of compression air and urea after to the injection nozzle 5 is restarted. When choking of the injection nozzle 5 is generated, therefore, choking can be eliminated even when exhaust temperature in an exhaust tube 4 is low. NOx emission control efficiency can thus be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、移動車両搭載のディーゼルエンジン、ガソリンエンジン等から排出される窒素酸化物（ＮＯｘ）を、還元剤を用いて還元除去する排気浄化装置に関し、特に、還元剤を還元触媒の排気上流側に供給する噴射ノズルの目詰まりが発生した際にその目詰まりを解消してＮＯｘの浄化処理の効率を向上するエンジンの排気浄化装置に係るものである。   The present invention relates to an exhaust purification device that reduces and removes nitrogen oxides (NOx) discharged from a diesel engine, a gasoline engine or the like mounted on a moving vehicle by using a reducing agent, and in particular, an exhaust upstream side of a reducing catalyst. The present invention relates to an engine exhaust gas purification device that improves the efficiency of NOx purification processing by eliminating clogging of an injection nozzle that is supplied to the engine.

エンジンから排出される排気中の微粒子物質（ＰＭ）のうち、特にＮＯｘを除去して排気を浄化するシステムとして、いくつかの排気浄化装置が提案されている。この排気浄化装置は、エンジンの排気系に還元触媒を置き、該還元触媒の上流側の排気通路に還元剤を噴射供給することにより、排気中のＮＯｘと還元剤とを触媒還元反応させ、ＮＯｘを無害成分に浄化処理するものである。還元剤は貯蔵タンクに常温で液体状態に貯蔵され、必要量を噴射ノズルから噴射供給する。還元反応は、ＮＯｘとの反応性の良いアンモニアを用いるもので、還元剤としては、加水分解してアンモニアを容易に発生する尿素水溶液、アンモニア水溶液、その他の還元剤水溶液が用いられる（例えば、特許文献１参照）。
特開２０００−２７６２７号公報 Several exhaust emission control devices have been proposed as a system for purifying exhaust gas by removing NOx from particulate matter (PM) in exhaust gas discharged from the engine. This exhaust purification device places a reduction catalyst in an exhaust system of an engine, and injects and supplies a reducing agent into an exhaust passage upstream of the reduction catalyst, thereby causing NOx and reducing agent in the exhaust to undergo a catalytic reduction reaction, thereby reducing NOx. Is purified to harmless components. The reducing agent is stored in a storage tank in a liquid state at room temperature, and a required amount is injected and supplied from an injection nozzle. In the reduction reaction, ammonia having good reactivity with NOx is used, and as the reducing agent, an aqueous urea solution, an aqueous ammonia solution, or other reducing agent aqueous solution that easily generates ammonia by hydrolysis is used (for example, patents). Reference 1).
JP 2000-27627 A

しかし、上記従来の排気浄化装置においては、エンジンの運転状態（排気温度やＮＯｘ排出量など）に応じて還元剤の供給量を制御するが、エンジンの運転状態によっては、排気通路内に設けられた噴射ノズルの噴射孔又はそれに至る通路が目詰まりを起こし、還元剤を十分に供給できなくなる場合がある。その結果、上記還元触媒上でのＮＯｘの還元反応がスムーズに進行せず、ＮＯｘが排出される虞がある。   However, in the conventional exhaust purification device, the supply amount of the reducing agent is controlled in accordance with the engine operating state (exhaust temperature, NOx emission amount, etc.). However, depending on the engine operating state, it is provided in the exhaust passage. In some cases, the injection hole of the injection nozzle or the passage leading to the injection nozzle is clogged, and the reducing agent cannot be supplied sufficiently. As a result, the reduction reaction of NOx on the reduction catalyst does not proceed smoothly, and there is a possibility that NOx is discharged.

上記噴射ノズルの目詰まりは、還元剤としての尿素水溶液（以下、「尿素水」という）中の尿素が噴射孔又はそれに至る通路内で結晶化して凝固したもの（以下、「固体尿素」という）が主な原因である。これは、尿素水は１００℃で結晶化するので、尿素水が１００℃以上に加熱されると尿素結晶が発生するからである。しかし、固体尿素の融点は１３２℃であるので、エンジンからの排気により噴射ノズル近傍の排気温度が上昇して該噴射ノズルへの入熱が増大すれば、上記固体尿素は融解してノズルの目詰まりは解消される。   The injection nozzle is clogged when urea in an aqueous urea solution (hereinafter referred to as “urea water”) as a reducing agent is crystallized and solidified in an injection hole or a passage leading to it (hereinafter referred to as “solid urea”). Is the main cause. This is because urea water is crystallized at 100 ° C., and when urea water is heated to 100 ° C. or higher, urea crystals are generated. However, since the melting point of solid urea is 132 ° C., if the exhaust temperature in the vicinity of the injection nozzle rises due to exhaust from the engine and the heat input to the injection nozzle increases, the solid urea will melt and the nozzle will be The clog is eliminated.

ところが、還元剤供給手段が、噴射ノズルに対して尿素水と共に圧縮空気を供給し該尿素水を霧化して噴射する、いわゆるエアアシストタイプの還元剤供給手段である場合は、噴射ノズルに常時供給される圧縮空気がノズル内部を冷却するため、ノズル内部の温度が１３２℃以上に上がらず、固体尿素の融解が妨げられる。したがって、上記噴射ノズルの内部に結晶化して凝固した固体尿素が付着して、ノズルが目詰まりを起こす虞がある。なお、この場合、噴射ノズル内部の温度を上げて固体尿素を融解させるために、排気通路内の排気温度を高くすることが考えられるが、これはエンジンにとって得策ではない。   However, when the reducing agent supply means is a so-called air assist type reducing agent supply means that supplies compressed air together with urea water to the injection nozzle and atomizes and injects the urea water, the supply is always supplied to the injection nozzle. Since the compressed air to be cooled cools the inside of the nozzle, the temperature inside the nozzle does not rise to 132 ° C. or more, and the melting of the solid urea is prevented. Therefore, there is a possibility that solid urea which is crystallized and solidified adheres to the inside of the injection nozzle and the nozzle is clogged. In this case, it is conceivable to increase the exhaust temperature in the exhaust passage in order to increase the temperature inside the injection nozzle and melt the solid urea, but this is not a good measure for the engine.

そこで、本発明は、このような問題点に対処し、還元剤を還元触媒の排気上流側に供給する噴射ノズルの目詰まりが発生した際に、排気通路内の排気温度が低くてもその目詰まりを解消してＮＯｘの浄化処理の効率を向上するエンジンの排気浄化装置を提供することを目的とする。   Therefore, the present invention addresses such problems, and when the injection nozzle that supplies the reducing agent to the exhaust upstream side of the reduction catalyst is clogged, even if the exhaust temperature in the exhaust passage is low, the An object of the present invention is to provide an engine exhaust purification device that eliminates clogging and improves the efficiency of NOx purification treatment.

請求項１に記載の排気浄化装置では、エンジンの排気系に配設され、排気中の窒素酸化物を還元剤により還元浄化する還元触媒と、還元剤と共に圧縮空気が供給され該還元剤を霧化して、前記排気系の排気通路内にて前記還元触媒の排気上流側に噴射供給する噴射ノズルを有する還元剤供給手段と、前記噴射ノズルの排気上流側の近傍に設けられ、排気通路内の排気温度を検出する温度検出手段と、を備えたエンジンの排気浄化装置であって、前記還元剤供給手段は、前記噴射ノズルの内部圧力を検出する圧力検出手段を備え、該噴射ノズルの内部圧力の検出信号を用いて、その圧力が所定値以上となったら噴射ノズルへの圧縮空気と還元剤の供給を停止し、前記温度検出手段からの排気温度の検出信号を用いて、噴射ノズル近傍の排気温度が還元剤の融点以上となったら噴射ノズルへ圧縮空気と還元剤の供給を再開させることを特徴とする。   The exhaust emission control device according to claim 1 is provided in an exhaust system of the engine and reduces and purifies nitrogen oxides in the exhaust gas with a reducing agent, and compressed air is supplied together with the reducing agent, and the reducing agent is atomized. A reducing agent supply means having an injection nozzle for supplying the exhaust gas to the exhaust upstream side of the reduction catalyst in the exhaust passage of the exhaust system, and provided in the vicinity of the exhaust upstream side of the injection nozzle, An exhaust gas purifying device for an engine comprising: a temperature detecting means for detecting an exhaust gas temperature, wherein the reducing agent supply means comprises a pressure detecting means for detecting an internal pressure of the injection nozzle, and the internal pressure of the injection nozzle When the pressure exceeds a predetermined value, the supply of compressed air and reducing agent to the injection nozzle is stopped, and the exhaust temperature detection signal from the temperature detection means is used to detect the vicinity of the injection nozzle. Exhaust gas temperature Thereby resuming the supply of the If becomes equal to or higher than the melting point of the reducing agent to the injection nozzle and the compressed air reducing agent, characterized in.

このような構成により、還元剤供給手段は、圧力検出手段で検出した噴射ノズルの内部圧力の検出信号を用いて、上記検出した圧力が所定値以上となったら噴射ノズルへの圧縮空気と還元剤の供給を停止し、温度検出手段からの排気温度の検出信号を用いて、噴射ノズル近傍の排気温度が還元剤の融点以上となったら噴射ノズルへ圧縮空気と還元剤の供給を再開させる。これにより、ノズル内部の冷却を抑え、排気通路内の排気温度で噴射ノズルの目詰まりを解消する。   With such a configuration, the reducing agent supply means uses the detection signal of the internal pressure of the injection nozzle detected by the pressure detection means, and when the detected pressure exceeds a predetermined value, the compressed air and the reducing agent to the injection nozzle And the supply of compressed air and reducing agent to the injection nozzle is resumed when the exhaust temperature in the vicinity of the injection nozzle becomes equal to or higher than the melting point of the reducing agent using the exhaust temperature detection signal from the temperature detecting means. Thereby, cooling inside the nozzle is suppressed, and clogging of the injection nozzle is eliminated at the exhaust temperature in the exhaust passage.

請求項２に記載の発明では、前記還元剤供給手段は、前記圧力検出手段からの噴射ノズルの内部圧力の検出信号を入力すると共に前記温度検出手段からの排気温度の検出信号を入力し、噴射ノズルの内部圧力が所定値以上となったら噴射ノズルへの圧縮空気と還元剤の供給を停止し、噴射ノズル近傍の排気温度が還元剤の融点以上となったら噴射ノズルへ圧縮空気と還元剤の供給を再開するように制御する制御回路を備えたことを特徴とする。これにより、還元剤供給手段に備えられた制御回路で、圧力検出手段からの噴射ノズルの内部圧力の検出信号を入力すると共に前記温度検出手段からの排気温度の検出信号を入力し、噴射ノズルの内部圧力が所定値以上となったら噴射ノズルへの圧縮空気と還元剤の供給を停止し、噴射ノズル近傍の排気温度が還元剤の融点以上となったら噴射ノズルへ圧縮空気と還元剤の供給を再開するように制御する。   According to a second aspect of the present invention, the reducing agent supply means inputs the detection signal of the internal pressure of the injection nozzle from the pressure detection means and inputs the detection signal of the exhaust temperature from the temperature detection means, When the internal pressure of the nozzle exceeds a predetermined value, supply of compressed air and reducing agent to the injection nozzle is stopped, and when the exhaust temperature near the injection nozzle exceeds the melting point of the reducing agent, compressed air and reducing agent are supplied to the injection nozzle. A control circuit for controlling the supply to be resumed is provided. As a result, the control circuit provided in the reducing agent supply means inputs the detection signal of the internal pressure of the injection nozzle from the pressure detection means and also inputs the detection signal of the exhaust temperature from the temperature detection means. When the internal pressure exceeds the specified value, supply of compressed air and reducing agent to the injection nozzle is stopped, and when the exhaust temperature near the injection nozzle exceeds the melting point of the reducing agent, supply of compressed air and reducing agent to the injection nozzle is stopped. Control to resume.

請求項３に記載の発明では、前記還元剤は、尿素水溶液であることを特徴とする。これにより、加水分解してアンモニアを容易に発生する尿素水溶液を還元剤として、排気中の窒素酸化物を還元浄化する。   The invention according to claim 3 is characterized in that the reducing agent is an aqueous urea solution. Thus, nitrogen oxides in the exhaust gas are reduced and purified using an aqueous urea solution that easily generates ammonia by hydrolysis as a reducing agent.

請求項４に記載の発明では、前記噴射ノズルへ圧縮空気と還元剤の供給を再開する際における噴射ノズル近傍の排気温度は、１３２℃以上であることを特徴とする。これにより、噴射ノズルの内部を、尿素水溶液中の尿素の融点以上の温度まで加熱する。   The invention according to claim 4 is characterized in that the exhaust temperature in the vicinity of the injection nozzle when restarting the supply of the compressed air and the reducing agent to the injection nozzle is 132 ° C. or more. Thereby, the inside of the injection nozzle is heated to a temperature not lower than the melting point of urea in the urea aqueous solution.

請求項１に係る発明によれば、噴射ノズルが目詰まりを起こしたと判断した場合は、該噴射ノズルへの圧縮空気と還元剤の供給を停止してノズル内部の冷却を抑え、この状態で排気通路内の排気による加熱でノズル内部の還元剤が融解したと判断した場合は、該噴射ノズルへ圧縮空気と還元剤の供給を再開させることができる。これにより、噴射ノズルの目詰まりが発生した際に、排気通路内の排気温度が低くてもその目詰まりを解消することができる。したがって、ＮＯｘの浄化処理の効率を向上することができる。   According to the first aspect of the present invention, when it is determined that the injection nozzle is clogged, the supply of the compressed air and the reducing agent to the injection nozzle is stopped to suppress the cooling inside the nozzle, and the exhaust gas is exhausted in this state. When it is determined that the reducing agent inside the nozzle has melted due to the heating by the exhaust in the passage, the supply of the compressed air and the reducing agent to the injection nozzle can be resumed. Thus, when the injection nozzle is clogged, the clogging can be eliminated even if the exhaust temperature in the exhaust passage is low. Therefore, the efficiency of the NOx purification process can be improved.

また、請求項２に係る発明によれば、還元剤供給手段に備えられた制御回路により、噴射ノズルの内部圧力が所定値以上となったら噴射ノズルが目詰まりを起こしたと判断して、噴射ノズルへの圧縮空気と還元剤の供給を停止し、噴射ノズル近傍の排気温度が還元剤の融点以上となったらその排気による加熱でノズル内部の還元剤が融解したと判断して、噴射ノズルへ圧縮空気と還元剤の供給を再開するように制御することができる。これにより、噴射ノズルの目詰まりが発生した際に、排気通路内の排気温度が低くてもその目詰まりを解消することができ、ＮＯｘの浄化処理の効率を向上することができる。   According to the invention of claim 2, the control circuit provided in the reducing agent supply means determines that the injection nozzle is clogged when the internal pressure of the injection nozzle becomes equal to or higher than a predetermined value, and the injection nozzle When the supply of compressed air and reducing agent to the nozzle is stopped, and the exhaust temperature near the injection nozzle reaches or exceeds the melting point of the reducing agent, it is determined that the reducing agent inside the nozzle has melted due to heating by the exhaust, and compression is performed to the injection nozzle The supply of air and reducing agent can be controlled to resume. As a result, when the clogging of the injection nozzle occurs, the clogging can be eliminated even if the exhaust temperature in the exhaust passage is low, and the efficiency of the NOx purification process can be improved.

さらに、請求項３に係る発明によれば、還元剤としてアンモニアを直接使用することなく、加水分解してアンモニアを容易に発生する尿素水溶液を使用することで、排気中のＮＯｘを無害成分に転化して、ＮＯｘの浄化処理の効率を向上することができる。   Furthermore, according to the invention of claim 3, NOx in the exhaust gas is converted into harmless components by using a urea aqueous solution that easily generates ammonia by hydrolysis without directly using ammonia as a reducing agent. Thus, the efficiency of the NOx purification process can be improved.

さらにまた、請求項４に係る発明によれば、エンジンからの排気を利用して噴射ノズルの内部を尿素の融点以上に加熱することができ、ノズル内部の固体尿素を融解して該噴射ノズルの目詰まりを解消することができる。これにより、ＮＯｘの浄化処理の効率を向上することができる。   Furthermore, according to the invention of claim 4, the inside of the injection nozzle can be heated to the melting point or higher of urea using exhaust from the engine, and the solid urea in the nozzle is melted to melt the injection nozzle. Clogging can be eliminated. Thereby, the efficiency of the purification process of NOx can be improved.

以下、本発明の実施形態を添付図面に基づいて詳細に説明する。   Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

図１は本発明によるエンジンの排気浄化装置の実施形態を示す図である。この排気浄化装置は、移動車両搭載のディーゼルエンジン、ガソリンエンジン等から排出されるＮＯｘを、還元剤を用いて還元除去するものである。ガソリンあるいは軽油を燃料とするエンジン１の排気は、排気マニフォ−ルド２からＮＯｘの還元触媒３が配設された排気管４を経由して大気中に排出される。詳細には、排気通路としての排気管４には排気上流側から順に、一酸化窒素（ＮＯ）の酸化触媒、ＮＯｘの還元触媒、アンモニア酸化触媒の３つの触媒が配設され、その前後に温度センサ、ＮＯｘセンサ等が配設されて排気系が構成されるが、細部の構成は図示していない。   FIG. 1 is a view showing an embodiment of an exhaust emission control device for an engine according to the present invention. This exhaust purification device reduces and removes NOx discharged from a diesel engine, a gasoline engine or the like mounted on a moving vehicle using a reducing agent. The exhaust of the engine 1 using gasoline or light oil as fuel is discharged from the exhaust manifold 2 to the atmosphere via an exhaust pipe 4 provided with a NOx reduction catalyst 3. Specifically, the exhaust pipe 4 serving as an exhaust passage is provided with three catalysts, a nitric oxide (NO) oxidation catalyst, a NOx reduction catalyst, and an ammonia oxidation catalyst, in that order from the upstream side of the exhaust. Although an exhaust system is configured by arranging sensors, NOx sensors, etc., the detailed configuration is not shown.

上記ＮＯｘの還元触媒３は、排気管４内を通る排気中のＮＯｘを還元剤により還元浄化するもので、セラミックのコーディライトやＦｅ−Ｃｒ−Ａｌ系の耐熱鋼から成るハニカム形状の横断面を有するモノリスタイプの触媒担体に、例えばゼオライト系の活性成分が担持されている。そして、上記触媒担体に担持された活性成分は、還元剤の供給を受けて活性化し、ＮＯｘを効果的に無害物質に浄化させる。   The NOx reduction catalyst 3 reduces and purifies NOx in the exhaust gas passing through the exhaust pipe 4 with a reducing agent. The NOx reduction catalyst 3 has a honeycomb-shaped cross section made of ceramic cordierite or Fe-Cr-Al heat-resistant steel. For example, a zeolite-type active component is supported on the monolith type catalyst carrier. Then, the active component carried on the catalyst carrier is activated upon receiving the supply of the reducing agent, and effectively purifies NOx into a harmless substance.

上記排気管４の内部にてＮＯｘの還元触媒３の排気上流側には、噴射ノズル５が配設されている。この噴射ノズル５は、還元剤を上記ＮＯｘの還元触媒３の排気上流側に供給するもので、還元剤供給装置６を介して還元剤と共に圧縮空気が供給され、該還元剤を霧化して噴射供給するようになっている。このような装置は、エアアシストタイプと呼ばれている。ここで、噴射ノズル５は、排気管４内にて排気の流れ方向Ａと略平行に下流側に向けて配設され、或いは適宜の角度で斜めに傾斜して配設されている。また、還元剤供給装置６には、貯蔵タンク７内に貯留された還元剤が供給配管８を通じて供給される。そして、上記噴射ノズル５と還元剤供給装置６とで、還元剤をＮＯｘの還元触媒３の排気上流側に供給する還元剤供給手段を構成している。   An injection nozzle 5 is disposed in the exhaust pipe 4 on the exhaust upstream side of the NOx reduction catalyst 3. The injection nozzle 5 supplies a reducing agent to the exhaust upstream side of the NOx reduction catalyst 3. Compressed air is supplied together with the reducing agent via the reducing agent supply device 6, and the reducing agent is atomized and injected. It comes to supply. Such an apparatus is called an air assist type. Here, the injection nozzle 5 is disposed in the exhaust pipe 4 toward the downstream side substantially parallel to the flow direction A of the exhaust gas, or is inclined obliquely at an appropriate angle. The reducing agent supply device 6 is supplied with the reducing agent stored in the storage tank 7 through the supply pipe 8. The injection nozzle 5 and the reducing agent supply device 6 constitute reducing agent supply means for supplying the reducing agent to the exhaust upstream side of the NOx reduction catalyst 3.

この実施形態では、上記噴射ノズル５で噴射供給する還元剤として尿素水溶液（尿素水）を用いる。他にアンモニア水溶液等を用いてもよい。そして、噴射ノズル５で噴射供給された尿素水は、排気管４内の排気熱により加水分解してアンモニアを容易に発生する。得られたアンモニアは、ＮＯｘの還元触媒３において排気中のＮＯｘと反応し、水及び無害なガスに浄化される。尿素水は、固体もしくは粉体の尿素の水溶液で、貯蔵タンク７に貯留されており、供給配管８を通じて還元剤供給装置６に供給されるようになっている。   In this embodiment, a urea aqueous solution (urea water) is used as a reducing agent to be supplied by injection from the injection nozzle 5. In addition, an aqueous ammonia solution or the like may be used. The urea water injected and supplied from the injection nozzle 5 is hydrolyzed by the exhaust heat in the exhaust pipe 4 to easily generate ammonia. The obtained ammonia reacts with NOx in the exhaust gas in the NOx reduction catalyst 3 to be purified into water and harmless gas. The urea water is a solid or powdery urea aqueous solution, stored in the storage tank 7, and supplied to the reducing agent supply device 6 through the supply pipe 8.

上記排気管４の内部にて噴射ノズル５の排気上流側の近傍には、排気温度センサ９が設けられている。この排気温度センサ９は、排気管４内の排気温度を検出する温度検出手段となるものであり、この実施形態では上記噴射ノズル５の排気上流側近傍の排気温度を検出するようになっている。そして、この排気温度センサ９で検出した排気温度の検出信号は、還元剤供給装置６に送られるようになっている。   An exhaust temperature sensor 9 is provided in the vicinity of the upstream side of the exhaust of the injection nozzle 5 inside the exhaust pipe 4. The exhaust temperature sensor 9 serves as temperature detection means for detecting the exhaust temperature in the exhaust pipe 4, and in this embodiment, the exhaust temperature in the vicinity of the exhaust upstream side of the injection nozzle 5 is detected. . The exhaust temperature detection signal detected by the exhaust temperature sensor 9 is sent to the reducing agent supply device 6.

上記還元剤供給装置６は、前述のようにエアアシストタイプと呼ばれるもので、図２に示すように、図１に示す貯蔵タンク７からの供給配管８の途中に設けられ尿素水の圧力を上げる昇圧ポンプ１０と、この昇圧ポンプ１０の下流側に設けられ尿素水の通路を開閉する供給バルブ１１と、図示省略の圧縮空気源からのエア供給配管１２の途中に設けられ圧縮空気の通路を開閉するエア供給バルブ１３とを備えて成る。   As described above, the reducing agent supply device 6 is called an air assist type. As shown in FIG. 2, the reducing agent supply device 6 is provided in the middle of the supply pipe 8 from the storage tank 7 shown in FIG. The booster pump 10, the supply valve 11 provided on the downstream side of the booster pump 10 for opening and closing the urea water passage, and the compressed air passage provided in the middle of the air supply pipe 12 from the compressed air source (not shown). The air supply valve 13 is provided.

ここで、本発明においては、上記還元剤供給装置６の内部に、圧力センサ１５を備え、さらに還元剤供給制御回路１４を備えている。圧力センサ１５は、上記噴射ノズル５の内部圧力を検出する圧力検出手段となるもので、例えば圧縮空気と尿素水を噴射ノズル５へ供給する共通配管１６の途中に設けられ、この共通配管１６の内部圧力を検出して噴射ノズル５の内部圧力を取り出している。   Here, in the present invention, the reducing agent supply device 6 includes a pressure sensor 15 and further includes a reducing agent supply control circuit 14. The pressure sensor 15 serves as a pressure detection means for detecting the internal pressure of the injection nozzle 5. For example, the pressure sensor 15 is provided in the middle of a common pipe 16 that supplies compressed air and urea water to the injection nozzle 5. The internal pressure of the injection nozzle 5 is extracted by detecting the internal pressure.

そして、上記還元剤供給装置６は、前記圧力センサ１５で検出した噴射ノズル５の内部圧力の検出信号Ｓ2を用いて、その圧力が所定値以上となったら噴射ノズル５への圧縮空気と尿素水の供給を停止し、前記排気温度センサ９からの排気温度の検出信号Ｓ1を用いて、噴射ノズル５近傍の排気温度が尿素水の融点（１３２℃）以上となったら噴射ノズル５へ圧縮空気と尿素水の供給を再開させるように構成されている。 Then, the reducing agent supply device 6, using the detection signal S 2 of the internal pressure of the injection nozzle 5 detected by the pressure sensor 15, compressed air and urea of the pressure to the injection nozzle 5 If equal to or greater than the predetermined value Water supply is stopped, and when the exhaust temperature detection signal S 1 from the exhaust temperature sensor 9 is used and the exhaust temperature in the vicinity of the injection nozzle 5 becomes equal to or higher than the melting point (132 ° C.) of urea water, it is compressed to the injection nozzle 5. The supply of air and urea water is resumed.

また、上記還元剤供給制御回路１４は、前記圧力センサ１５からの噴射ノズル５の内部圧力の検出信号Ｓ2を入力すると共に前記排気温度センサ９からの排気温度の検出信号Ｓ1を入力し、噴射ノズル５の内部圧力が所定値以上となったら噴射ノズル５への圧縮空気と尿素水の供給を停止し、噴射ノズル５近傍の排気温度が尿素水の融点（１３２℃）以上となったら噴射ノズル５へ圧縮空気と尿素水の供給を再開するように制御するもので、例えば制御用マイクロコンピュータ（ＭＰＵ）から成り、その制御された供給タイミングに応じて、上記昇圧ポンプ１０及び供給バルブ１１並びにエア供給バルブ１３に制御信号を送り、噴射ノズル５に対する圧縮空気及び尿素水の供給停止及び再開を制御するようになっている。 The reducing agent supply control circuit 14 inputs the detection signal S 2 of the internal pressure of the injection nozzle 5 from the pressure sensor 15 and the detection signal S 1 of the exhaust temperature from the exhaust temperature sensor 9, The supply of compressed air and urea water to the injection nozzle 5 is stopped when the internal pressure of the injection nozzle 5 exceeds a predetermined value, and the injection is performed when the exhaust temperature near the injection nozzle 5 exceeds the melting point (132 ° C.) of urea water. The control is performed so that the supply of compressed air and urea water to the nozzle 5 is resumed. The control includes, for example, a control microcomputer (MPU), and the boost pump 10, the supply valve 11, and the like according to the controlled supply timing. A control signal is sent to the air supply valve 13 to control the supply stop and restart of the compressed air and urea water to the injection nozzle 5.

次に、このように構成された排気浄化装置の動作について、図２及び図３を参照して説明する。まず、図１において、エンジン１の運転による排気は、排気マニフォ−ルド２から排気管４を経由して、該排気管４内の途中に配設されたＮＯｘの還元触媒３を通り、排気管４の端部排出口から大気中に排出される。このとき、上記排気管４の内部にてＮＯｘの還元触媒３の排気上流側に配設された噴射ノズル５から尿素水が噴射される。この噴射ノズル５には、尿素水の貯蔵タンク７から供給配管８を介して尿素水が還元剤供給装置６に供給された後、この還元剤供給装置６の動作により圧縮空気と共に尿素水が供給され、該噴射ノズル５は尿素水を霧化して噴射供給する。   Next, the operation of the exhaust emission control device configured as described above will be described with reference to FIGS. First, in FIG. 1, exhaust from the operation of the engine 1 passes through the exhaust manifold 2, the exhaust pipe 4, the NOx reduction catalyst 3 disposed in the exhaust pipe 4, and the exhaust pipe. 4 is discharged into the atmosphere from the end discharge port. At this time, urea water is injected from the injection nozzle 5 disposed upstream of the NOx reduction catalyst 3 in the exhaust pipe 4. After the urea water is supplied to the injection nozzle 5 from the urea water storage tank 7 through the supply pipe 8 to the reducing agent supply device 6, the urea water is supplied together with the compressed air by the operation of the reducing agent supply device 6. The injection nozzle 5 atomizes the urea water and supplies it by injection.

この状態で、図２において、上記噴射ノズル５の排気上流側の近傍に設けられた排気温度センサ９により排気管４内の排気温度を検出して、その検出信号Ｓ1が還元剤供給装置６の還元剤供給制御回路１４へ送られる。また、噴射ノズル５への共通配管１６の途中に設けられた圧力センサ１５により該噴射ノズル５の内部圧力を検出して、その検出信号Ｓ2が同じく還元剤供給制御回路１４へ送られる。 In this state, in FIG. 2, by detecting the exhaust temperature in the exhaust pipe 4 by the exhaust temperature sensor 9 provided near the exhaust upstream side of the injection nozzle 5, the detection signal S 1 is the reducing agent supply device 6 To the reducing agent supply control circuit 14. Further, the internal pressure of the injection nozzle 5 is detected by a pressure sensor 15 provided in the middle of the common pipe 16 to the injection nozzle 5, and the detection signal S 2 is also sent to the reducing agent supply control circuit 14.

まず、還元剤供給制御回路１４は、上記圧力センサ１５からの検出信号Ｓ2を用いて、噴射ノズル５の内部圧力（以下、「ノズル内圧」と略称する）をモニタし、所定圧Ｐ1以上か否かを判断する（図３のステップＳ１）。この場合、噴射ノズル５が目詰まりを起こすと、エア供給配管１２からの圧縮空気の供給によりノズル内圧が上昇することから、上記所定圧Ｐ1を目詰まりが発生した際の圧力に設定しておくことにより、ノズル内圧の上昇でノズルの目詰まりを判断できる。いま、ノズル内圧が所定圧Ｐ1未満の場合は、ノズル目詰まりが発生していないと判断して、ステップＳ１は“NO”側に進んでそのままノズル内圧を監視する。 First, the reducing agent supply control circuit 14 uses the detection signal S 2 from the pressure sensor 15 to monitor the internal pressure of the injection nozzle 5 (hereinafter abbreviated as “nozzle internal pressure”), and exceeds a predetermined pressure P 1. (Step S1 in FIG. 3). In this case, the injection nozzle 5 is clogged, since the nozzle internal pressure by the supply of compressed air from the air supply pipe 12 is increased, by setting the pressure at which the predetermined pressure P 1 clogging occurs Therefore, it is possible to determine whether the nozzle is clogged by an increase in the nozzle internal pressure. Now, if the nozzle internal pressure is below the predetermined pressure P 1, it is determined that the nozzle clogging has not occurred, step S1 monitors nozzle pressure as it proceeds to the "NO" side.

その後、ノズル内圧が所定圧Ｐ1以上になった場合は、ステップＳ１は“YES”側に進んで、ステップＳ２に入る。ここでは、ノズル内圧が所定圧Ｐ1以上の状態が継続する時間をカウントする。そして、所定圧Ｐ1以上の状態の継続時間が所定時間ｔ1以上か否かを判断する（ステップＳ３）。これは、圧力センサ１５の誤差又は誤動作等を排除して装置の信頼性を向上するため、ノズル内圧が所定圧Ｐ1以上の状態が所定時間ｔ1として設定された値以上に継続して初めてノズル目詰まりが発生したと判断するためである。いま、継続時間が所定時間ｔ1未満の場合は、ノズル目詰まりが発生していないと判断して、ステップＳ３は“NO”側に進んでステップＳ４に入る。そして、再度ノズル内圧が所定圧Ｐ1以上か否かを判断し、“YES”側に進んで継続時間を監視する。 Thereafter, if the nozzle internal pressure reaches a predetermined pressure P 1 or more, step S1 proceeds to the "YES" side and enters step S2. Here counts the time that the nozzle internal pressure is the predetermined pressure P 1 or more condition continues. The duration of the predetermined pressure P 1 or more states to determine whether or not a predetermined time t 1 or more (step S3). In order to eliminate the error or malfunction of the pressure sensor 15 and improve the reliability of the apparatus, this is not until the state in which the nozzle internal pressure is equal to or higher than the predetermined pressure P 1 continues to exceed the value set as the predetermined time t 1. This is to determine that nozzle clogging has occurred. If the duration is less than the predetermined time t 1 , it is determined that nozzle clogging has not occurred, and step S3 proceeds to “NO” and enters step S4. Then, it is determined again whether the nozzle internal pressure is equal to or higher than the predetermined pressure P 1, and the process proceeds to “YES” to monitor the duration time.

その後、継続時間が所定時間ｔ1以上になった場合は、噴射ノズル５に目詰まりが発生したと判断して、ステップＳ３は“YES”側に進んで、ステップＳ５に入る。ここでは、図２に示すエア供給バルブ１３及び供給バルブ１１を閉じて、噴射ノズル５に対する圧縮空気の供給及び尿素水の供給を停止する。これにより、上記噴射ノズル５の内部が圧縮空気と尿素水で冷却されるのを抑え、排気管４内を流れる排気により加熱され、ノズル内部で凝固した固体尿素の融解を進行させる。 Then, when the duration reaches a predetermined time t 1 or more, it is determined that the clogging in the injection nozzle 5 has occurred, step S3 proceeds to the "YES" side and enters step S5. Here, the air supply valve 13 and the supply valve 11 shown in FIG. 2 are closed, and the supply of compressed air and urea water to the injection nozzle 5 are stopped. Thereby, the inside of the injection nozzle 5 is suppressed from being cooled by the compressed air and urea water, and the solid urea heated by the exhaust gas flowing in the exhaust pipe 4 and solidified inside the nozzle is advanced.

そして、図２に示す排気温度センサ９からの検出信号Ｓ1を用いて、噴射ノズル５近傍の排気温度（以下、「ノズル近傍温度」と略称する）をモニタし、所定温度Ｔ1以上か否かを判断する（ステップＳ６）。この場合、固体尿素の融点は１３２℃であるので、Ｔ1を１３２℃以上に設定しておくことにより、上記噴射ノズル５内の固体尿素を融解させることができる。いま、ノズル近傍温度が所定温度Ｔ1未満の場合は、固体尿素を融解できないと判断して、ステップＳ６は“NO”側に進んでそのままノズル近傍温度を監視する。 Then, using the detection signal S 1 from the exhaust temperature sensor 9 shown in FIG. 2, the exhaust temperature in the vicinity of the injection nozzle 5 (hereinafter abbreviated as “near nozzle temperature”) is monitored to determine whether or not it is equal to or higher than a predetermined temperature T 1. Is determined (step S6). In this case, since the melting point of the solid urea is 132 ° C., the solid urea in the injection nozzle 5 can be melted by setting T 1 to 132 ° C. or higher. Now, if the nozzle vicinity temperature is lower than the predetermined temperature T 1, and determines that it can not melt the solid urea, step S6 monitors nozzle vicinity temperature as it proceeds to the "NO" side.

その後、ノズル近傍温度が所定温度Ｔ1以上になった場合は、ステップＳ６は“YES”側に進んで、ステップＳ７に入る。ここでは、ノズル近傍温度が所定温度Ｔ1以上の状態が継続する時間をカウントする。そして、所定温度Ｔ1以上の状態の継続時間が所定時間ｔ2以上か否かを判断する（ステップＳ８）。これは、排気温度センサ９の誤差又は誤動作等を排除して装置の信頼性を向上するため、ノズル近傍温度が所定温度Ｔ1以上の状態が所定時間ｔ2として設定された値以上に継続して初めて固体尿素が融解したと判断するためである。いま、継続時間が所定時間ｔ2未満の場合は、固体尿素が融解していないと判断して、ステップＳ８は“NO”側に進んでステップＳ９に入る。そして、再度ノズル近傍温度が所定温度Ｔ1以上か否かを判断し、“YES”側に進んで継続時間を監視する。 Then, when the nozzle vicinity temperature reaches 1 or more predetermined temperature T, the step S6 proceeds to the "YES" side and enters step S7. Here counts the time the nozzle vicinity temperature continues predetermined temperature above T 1 state. Then, it is determined whether or not the duration of the state of the predetermined temperature T 1 or more is the predetermined time t 2 or more (step S8). In order to eliminate the error or malfunction of the exhaust temperature sensor 9 and improve the reliability of the apparatus, the state in which the nozzle vicinity temperature is equal to or higher than the predetermined temperature T 1 continues to exceed the value set as the predetermined time t 2. This is because it is determined that the solid urea has melted for the first time. If the duration is less than the predetermined time t 2 , it is determined that the solid urea has not melted, and step S8 advances to “NO” and enters step S9. Then, it is determined whether or not the nozzle vicinity temperature again if a predetermined temperature above T 1, to monitor the duration proceeds to "YES" side.

その後、継続時間が所定時間ｔ2以上になった場合は、噴射ノズル５内の固体尿素が融解したと判断して、ステップＳ８は“YES”側に進んで、ステップＳ１０に入る。ここでは、図２に示すエア供給バルブ１３を開いて、噴射ノズル５に対する圧縮空気の供給を再開する。 Then, when the duration reaches a predetermined time t 2 or more, it is determined that the solid urea injection nozzle 5 has melted, the step S8 proceeds to "YES" side and enters step S10. Here, the air supply valve 13 shown in FIG. 2 is opened, and the supply of compressed air to the injection nozzle 5 is resumed.

そして、ノズル内圧が他の所定圧Ｐ2以下か否かを判断する（ステップＳ１１）。この場合、噴射ノズル５内の固体尿素が融解すれば、エア供給配管１２から圧縮空気を供給してもノズル内圧が一定圧より上昇することはないから、上記所定圧Ｐ2を目詰まりが発生していない状態のノズル内圧に設定しておくことにより、ノズル内圧の低下でノズル目詰まりの解消を判断できる。いま、ノズル内圧が所定圧Ｐ2以下となった場合は、固体尿素の融解によりノズル目詰まりが解消したと判断して、ステップＳ１１は“YES”側に進んで、ステップＳ１２に入る。ここでは、図２に示す供給バルブ１１を開いて、噴射ノズル５に対する尿素水の供給を再開する。これにより、噴射ノズル５は、ノズル目詰まりのない正常状態に復帰する。 Then, the nozzle internal pressure is determined whether another predetermined pressure P 2 less (step S11). In this case, if the solid urea injection nozzle 5 is melted, since never nozzle internal pressure by supplying compressed air from the air supply pipe 12 rises above a certain pressure, the predetermined pressure P 2 clogging occurs By setting the internal pressure of the nozzle in a non-operating state, it is possible to determine whether the nozzle clogging has been eliminated due to a decrease in the nozzle internal pressure. If the nozzle internal pressure is equal to or lower than the predetermined pressure P 2 , it is determined that the nozzle clogging has been eliminated by melting the solid urea, and step S11 proceeds to “YES” to enter step S12. Here, the supply valve 11 shown in FIG. 2 is opened, and the supply of urea water to the injection nozzle 5 is resumed. Thereby, the injection nozzle 5 returns to a normal state with no nozzle clogging.

一方、ノズル内圧が他の所定圧Ｐ2より高い場合は、固体尿素はまだ融解せずノズル目詰まりが解消していないと判断して、ステップＳ１１は“NO”側に進んで、ステップＳ１３で繰り返し回数Ｎｉのカウンタを“１”ずつインクリメントし、ステップＳ１４で繰り返し回数Ｎｉが予め定められた規定回数以内であることを判断して、前述のステップＳ５に戻る。そして、再び噴射ノズル５に対する圧縮空気の供給及び尿素水の供給を停止し、上述の各ステップを繰り返してノズル目詰まりの解消の動作を、規定回数だけ行う。 On the other hand, if the nozzle internal pressure is higher than the pressure P 2 elsewhere, the solid urea still determines that the nozzle clogging does not melt does not eliminate, the step S11 proceeds to "NO" side, in step S13 The counter of the number of repetitions Ni is incremented by “1”. In step S14, it is determined that the number of repetitions Ni is within a predetermined number of times, and the process returns to step S5. Then, the supply of compressed air and the supply of urea water to the injection nozzle 5 are stopped again, and the above steps are repeated to perform the operation for eliminating nozzle clogging a specified number of times.

このとき、ステップＳ１４において、繰り返し回数Ｎｉが規定回数を超えた場合は、“NO”側に進んで、エラー出力処理を行い（ステップＳ１５）、尿素水の供給系を停止し（ステップＳ１６）、動作を終了する。これにより、噴射ノズル５に対する圧縮空気の供給及び尿素水の供給を停止して、ノズル内部が冷却されるのを抑え、排気管４内を流れる排気により噴射ノズル５を加熱して、ノズル内部で凝固した固体尿素を融解してノズル目詰まりを解消できる。したがって、排気管４内の排気温度が低くても、噴射ノズル５の目詰まりを解消してＮＯｘの浄化処理の効率を向上することができる。   At this time, if the number of repetitions Ni exceeds the specified number in step S14, the process proceeds to “NO”, error output processing is performed (step S15), and the urea water supply system is stopped (step S16). End the operation. Thereby, the supply of compressed air and the supply of urea water to the injection nozzle 5 are stopped, the inside of the nozzle is suppressed from being cooled, the injection nozzle 5 is heated by the exhaust gas flowing in the exhaust pipe 4, and the inside of the nozzle is The clogged solid urea can be melted to eliminate nozzle clogging. Therefore, even when the exhaust temperature in the exhaust pipe 4 is low, the clogging of the injection nozzle 5 can be eliminated and the efficiency of the NOx purification process can be improved.

その後、エンジン１の運転停止により、噴射ノズル５からの尿素水の噴射を終了するには、還元剤供給装置６の動作により、まず貯蔵タンク７からの尿素水の供給を遮断し、その後しばらくは噴射ノズル５に圧縮空気だけを供給する。これにより、噴射ノズル５の噴射孔又はそれに至る通路から尿素水を追い出して、尿素水の噴射を終了する。このように、噴射ノズル５から尿素水を追い出すことで、噴射ノズル５に対する尿素水の供給停止時における尿素水の残留又はいわゆる「後ダレ」が発生せず、噴射孔又はそれに至る通路内で尿素水が結晶化して目詰まりを起こすのを防止することができる。   Thereafter, in order to end the injection of the urea water from the injection nozzle 5 by stopping the operation of the engine 1, the supply of the urea water from the storage tank 7 is first interrupted by the operation of the reducing agent supply device 6, and then for a while. Only compressed air is supplied to the injection nozzle 5. Thereby, urea water is expelled from the injection hole of the injection nozzle 5 or the passage leading to it, and the injection of urea water is terminated. In this way, the urea water is expelled from the injection nozzle 5 so that urea water does not remain or so-called “after-sag” when the supply of urea water to the injection nozzle 5 is stopped. It is possible to prevent water from crystallizing and causing clogging.

なお、図２においては、還元剤供給装置６内の圧力センサ１５は、圧縮空気と尿素水を噴射ノズル５へ供給する共通配管１６の途中に設けたものとしたが、本発明はこれに限られず、噴射ノズル５の内部に配設して、該噴射ノズル５の内部圧力を直接検出するようにしてもよい。   In FIG. 2, the pressure sensor 15 in the reducing agent supply device 6 is provided in the middle of the common pipe 16 that supplies the compressed air and the urea water to the injection nozzle 5, but the present invention is not limited to this. Instead, it may be arranged inside the injection nozzle 5 to directly detect the internal pressure of the injection nozzle 5.

本発明によるエンジンの排気浄化装置の実施形態を示す概念図である。It is a conceptual diagram which shows embodiment of the exhaust emission purification device of the engine by this invention. 上記排気浄化装置における還元剤供給装置及び噴射ノズルの構成及び動作を説明するための概要図である。It is a schematic diagram for demonstrating a structure and operation | movement of the reducing agent supply apparatus and injection nozzle in the said exhaust gas purification apparatus. 上記排気浄化装置の動作を説明するためのフローチャートである。It is a flowchart for demonstrating operation | movement of the said exhaust gas purification apparatus.

符号の説明Explanation of symbols

１…エンジン
３…還元触媒
４…排気管
５…噴射ノズル
６…還元剤供給装置
７…貯蔵タンク
８…供給配管
９…排気温度センサ
１１…尿素水の供給バルブ
１３…エア供給バルブ
１４…還元剤供給制御回路
１５…圧力センサ
１６…共通配管 DESCRIPTION OF SYMBOLS 1 ... Engine 3 ... Reduction catalyst 4 ... Exhaust pipe 5 ... Injection nozzle 6 ... Reducing agent supply device 7 ... Storage tank 8 ... Supply piping 9 ... Exhaust temperature sensor 11 ... Urea water supply valve 13 ... Air supply valve 14 ... Reducing agent Supply control circuit 15 ... Pressure sensor 16 ... Common piping

Claims (4)

エンジンの排気系に配設され、排気中の窒素酸化物を還元剤により還元浄化する還元触媒と、
還元剤と共に圧縮空気が供給され該還元剤を霧化して、前記排気系の排気通路内にて前記還元触媒の排気上流側に噴射供給する噴射ノズルを有する還元剤供給手段と、
前記噴射ノズルの排気上流側の近傍に設けられ、排気通路内の排気温度を検出する温度検出手段と、
を備えたエンジンの排気浄化装置であって、
前記還元剤供給手段は、前記噴射ノズルの内部圧力を検出する圧力検出手段を備え、該噴射ノズルの内部圧力の検出信号を用いて、その圧力が所定値以上となったら噴射ノズルへの圧縮空気と還元剤の供給を停止し、前記温度検出手段からの排気温度の検出信号を用いて、噴射ノズル近傍の排気温度が還元剤の融点以上となったら噴射ノズルへ圧縮空気と還元剤の供給を再開させることを特徴とするエンジンの排気浄化装置。 A reduction catalyst disposed in the exhaust system of the engine for reducing and purifying nitrogen oxides in the exhaust with a reducing agent;
Reducing agent supply means having an injection nozzle that is supplied with compressed air together with the reducing agent, atomizes the reducing agent, and injects it into the exhaust upstream side of the reduction catalyst in the exhaust passage of the exhaust system;
A temperature detecting means provided in the vicinity of the exhaust upstream side of the injection nozzle for detecting the exhaust temperature in the exhaust passage;
An exhaust emission control device for an engine equipped with
The reducing agent supply means includes pressure detection means for detecting an internal pressure of the injection nozzle, and when the pressure becomes a predetermined value or more using a detection signal of the internal pressure of the injection nozzle, compressed air to the injection nozzle When the exhaust temperature near the injection nozzle becomes equal to or higher than the melting point of the reducing agent, the compressed air and the reducing agent are supplied to the injection nozzle using the exhaust temperature detection signal from the temperature detecting means. An exhaust emission control device for an engine characterized by being restarted. 前記還元剤供給手段は、前記圧力検出手段からの噴射ノズルの内部圧力の検出信号を入力すると共に前記温度検出手段からの排気温度の検出信号を入力し、噴射ノズルの内部圧力が所定値以上となったら噴射ノズルへの圧縮空気と還元剤の供給を停止し、噴射ノズル近傍の排気温度が還元剤の融点以上となったら噴射ノズルへ圧縮空気と還元剤の供給を再開するように制御する制御回路を備えたことを特徴とする請求項１に記載のエンジンの排気浄化装置。   The reducing agent supply means inputs the detection signal of the internal pressure of the injection nozzle from the pressure detection means and also inputs the detection signal of the exhaust temperature from the temperature detection means, so that the internal pressure of the injection nozzle is not less than a predetermined value. Control to stop the supply of compressed air and reducing agent to the injection nozzle when it becomes, and to resume the supply of compressed air and reducing agent to the injection nozzle when the exhaust temperature near the injection nozzle exceeds the melting point of the reducing agent The engine exhaust gas purification apparatus according to claim 1, further comprising a circuit. 前記還元剤は、尿素水溶液であることを特徴とする請求項１又は２に記載のエンジンの排気浄化装置。   3. The engine exhaust gas purification apparatus according to claim 1, wherein the reducing agent is an aqueous urea solution. 前記噴射ノズルへ圧縮空気と還元剤の供給を再開する際における噴射ノズル近傍の排気温度は、１３２℃以上であることを特徴とする請求項３に記載のエンジンの排気浄化装置。   The engine exhaust gas purification apparatus according to claim 3, wherein an exhaust temperature in the vicinity of the injection nozzle when restarting the supply of the compressed air and the reducing agent to the injection nozzle is 132 ° C or higher.
JP2003344757A 2003-10-02 2003-10-02 Engine exhaust purification system Expired - Lifetime JP3732493B2 (en)

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PCT/JP2004/013305 WO2005033482A1 (en) 2003-10-02 2004-09-13 Exhaust gas cleaner for engine
ES04772987T ES2367485T3 (en) 2003-10-02 2004-09-13 EXHAUST GAS FILTER FOR AN ENGINE.
US10/574,341 US7703276B2 (en) 2003-10-02 2004-09-13 Exhaust gas purifying apparatus for engine
EP04772987A EP1672191B1 (en) 2003-10-02 2004-09-13 Exhaust gas cleaner for engine
AT04772987T ATE520868T1 (en) 2003-10-02 2004-09-13 EMISSION CLEANER FOR ENGINE
CNB2004800286338A CN100404808C (en) 2003-10-02 2004-09-13 Exhaust gas cleaner for engine
CN2008101106559A CN101328827B (en) 2003-10-02 2004-09-13 Exhaust gas purifying apparatus for engine

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