JP6728782B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Exhaust gas purification device for internal combustion engine Download PDF

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JP6728782B2
JP6728782B2 JP2016041294A JP2016041294A JP6728782B2 JP 6728782 B2 JP6728782 B2 JP 6728782B2 JP 2016041294 A JP2016041294 A JP 2016041294A JP 2016041294 A JP2016041294 A JP 2016041294A JP 6728782 B2 JP6728782 B2 JP 6728782B2
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catalyst
exhaust gas
casing
pipe
urea water
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JP2017155694A (en
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幸博 川島
幸博 川島
直 水上
直 水上
泰順 鈴木
泰順 鈴木
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Isuzu Motors Ltd
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Isuzu Motors Ltd
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Priority to CN201780014409.0A priority patent/CN108699939B/en
Priority to PCT/JP2017/007817 priority patent/WO2017150538A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/36—Arrangements for supply of additional fuel
    • 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
    • Y02T10/12—Improving ICE efficiencies

Description

本発明は、後処理ユニットを備えた内燃機関の排ガス浄化装置に関する。 The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine equipped with a post-treatment unit.

一般的に、内燃機関を搭載した車両においては、排気管の途中に設けられ、排ガス中の有害物質を浄化するための複数の触媒を有する後処理ユニットを備えた排ガス浄化装置が知られている。 Generally, in a vehicle equipped with an internal combustion engine, an exhaust gas purifying apparatus is known which is provided in the middle of an exhaust pipe and includes an aftertreatment unit having a plurality of catalysts for purifying harmful substances in exhaust gas. ..

特開２００３−１８４５４４号公報JP, 2003-184544, A 特開２００８−２０８７２７号公報JP, 2008-208727, A

上記の排ガス浄化装置においては、触媒の温度を高温に保持するために、後処理ユニットをケーシングに収容することが考えられる。 In the above exhaust gas purifying apparatus, it is considered that the post-treatment unit is housed in the casing in order to keep the temperature of the catalyst high.

一方、後処理ユニットが選択還元型ＮＯｘ触媒（ＳＣＲ：Selective Catalytic Reduction）を有する場合、ＮＯｘ触媒の上流側に還元剤としての尿素水が添加される。添加された尿素水は、排ガスと混合して蒸発しつつ、ＮＯｘ触媒に向かって延びる管部材の内部を流れ、ＮＯｘ触媒に供給される。しかし、尿素水が液相状態で管部材の内部に付着して滞留すると、その滞留する部位を腐食させる虞がある。 On the other hand, when the post-treatment unit has a selective reduction type NOx catalyst (SCR: Selective Catalytic Reduction), urea water as a reducing agent is added to the upstream side of the NOx catalyst. The added urea water flows inside the pipe member extending toward the NOx catalyst while being mixed with the exhaust gas and evaporated, and supplied to the NOx catalyst. However, if the urea water adheres to the inside of the pipe member in the liquid state and stays therein, there is a possibility that the staying site may be corroded.

そこで、本発明は、かかる事情に鑑みて創案され、その目的は、ケーシングに収容され、選択還元型ＮＯｘ触媒を備えた後処理ユニットにて、尿素水が滞留する部位を容易に交換することが可能な内燃機関の排ガス浄化装置を提供することにある。 Therefore, the present invention was devised in view of such circumstances, and an object thereof is to easily replace a portion where urea water is retained in a post-treatment unit that is housed in a casing and that includes a selective reduction type NOx catalyst. An object of the present invention is to provide an exhaust gas purifying device for an internal combustion engine.

本発明に係る内燃機関の排ガス浄化装置は、排気管と、前記排気管の途中に設けられ、排ガスを浄化するための複数の触媒を有する後処理ユニットと、前記後処理ユニットを収容するケーシングと、を備え、前記後処理ユニットは、選択還元型ＮＯｘ触媒と、前記選択還元型ＮＯｘ触媒の上流側から選択還元型ＮＯｘ触媒に向かって延び、排ガスが通過される管部材と、前記管部材内における前記選択還元型ＮＯｘ触媒の上流側の位置に尿素水を添加する添加弁と、を備え、前記管部材が、前記添加弁と前記選択還元型ＮＯｘ触媒の間の位置に、前記添加弁から添加された尿素水が滞留する部位を有し、前記部位が着脱可能とされ、前記ケーシングに前記部位が通過可能な開口部が設けられ、前記ケーシングに前記開口部を開閉可能に覆う蓋が設けられることを特徴とする。 An exhaust gas purification apparatus for an internal combustion engine according to the present invention, an exhaust pipe, a post-treatment unit having a plurality of catalysts for purifying the exhaust gas, which is provided in the middle of the exhaust pipe, and a casing that houses the post-treatment unit. The post-treatment unit includes a selective reduction NOx catalyst, a pipe member extending from an upstream side of the selective reduction NOx catalyst toward the selective reduction NOx catalyst, through which exhaust gas passes, and the inside of the pipe member. And an addition valve for adding urea water to a position upstream of the selective reduction NOx catalyst in the pipe member, wherein the pipe member is located at a position between the addition valve and the selective reduction NOx catalyst from the addition valve. There is a portion where the added urea water is retained, the portion is removable, the casing is provided with an opening through which the portion can pass, and the casing is provided with a lid for opening and closing the opening. It is characterized by being.

また、本発明に係る内燃機関の排ガス浄化装置は、排気管と、前記排気管の途中に設けられ、排ガスを浄化するための複数の触媒を有する後処理ユニットと、前記後処理ユニットを収容するケーシングと、を備え、前記後処理ユニットは、少なくとも一つの触媒を内設する管状の第１触媒ケーシングと、前記第１触媒ケーシングに並列して配置され、選択還元型ＮＯｘ触媒を内設する管状の第２触媒ケーシングと、前記第１触媒ケーシングと前記第２触媒ケーシングとの間の位置に配置され、前記第１触媒ケーシングの下流端と前記第２触媒ケーシングの上流端とを連結する連結管であって、排気流れ方向に沿って後方から前方に向かって延び、Ｕ字状に折り返されて後方に延びる折り返し部分を有する連結管と、前記折り返し部分の上流側から前記折り返し部分に向かって、後方から前方に尿素水を添加するように配置された尿素水添加弁と、を備え、前記折り返し部分は、着脱可能な前面部を有し、前記ケーシングの前面には、前記折り返し部分の前面部に対向する位置に前記前面部が通過可能な開口部が形成されると共に、その開口部を開閉可能に覆う蓋が設けられることを特徴とする。 Further, an exhaust gas purifying apparatus for an internal combustion engine according to the present invention accommodates an exhaust pipe, an aftertreatment unit that is provided in the middle of the exhaust pipe and has a plurality of catalysts for purifying the exhaust gas, and the aftertreatment unit. And a tubular first catalyst casing in which at least one catalyst is provided inside, and a tubular casing disposed in parallel with the first catalyst casing and in which a selective reduction type NOx catalyst is provided. Second catalyst casing, and a connecting pipe arranged at a position between the first catalyst casing and the second catalyst casing and connecting the downstream end of the first catalyst casing and the upstream end of the second catalyst casing. Of the connection pipe, which extends from the rear to the front along the exhaust flow direction, has a folded portion that is folded back in a U shape and extends rearward, and from the upstream side of the folded portion toward the folded portion, A urea water addition valve arranged to add urea water from the rear to the front, wherein the folded-back portion has a detachable front surface portion, and the front surface portion of the folded-back portion is provided on the front surface of the casing. An opening through which the front surface can pass is formed at a position opposite to, and a lid is provided to cover the opening so that the opening can be opened and closed.

本発明に係る内燃機関の排ガス浄化装置では、ケーシングに収容され、選択還元型ＮＯｘ触媒を備えた後処理ユニットにて、尿素水が滞留する部位を容易に交換することができるという優れた効果を発揮する。 In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, it is possible to easily replace the portion where urea water is retained in the aftertreatment unit housed in the casing and provided with the NOx selective reduction catalyst. Demonstrate.

本発明の一実施形態に係る排ガス浄化装置を示す概略構成図である。1 is a schematic configuration diagram showing an exhaust gas purifying apparatus according to an embodiment of the present invention.

以下、添付図面に基づいて、本発明の一実施形態を説明する。図１は、本発明の一実施形態に係る内燃機関の排ガス浄化装置を示す概略構成図である。 An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing an exhaust gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention.

図１に示すように、排ガス浄化装置１００は、内燃機関１の排ガスを通過させる排気管２と、排気管２の途中に設けられ、排ガスを浄化するための複数の触媒１０を有する後処理ユニット３と、後処理ユニット３を収容するケーシング４と、を含む。 As shown in FIG. 1, an exhaust gas purifying apparatus 100 includes an exhaust pipe 2 that allows exhaust gas of an internal combustion engine 1 to pass therethrough, and a post-treatment unit that is provided in the middle of the exhaust pipe 2 and has a plurality of catalysts 10 for purifying the exhaust gas. 3 and a casing 4 that houses the post-treatment unit 3.

内燃機関１は、図示しない車両に搭載された多気筒の圧縮着火式内燃機関、すなわちディーゼルエンジンである。内燃機関１には、各気筒１１から排出される排ガスを集合させる排気マニホールド１２が設けられる。 The internal combustion engine 1 is a multi-cylinder compression ignition type internal combustion engine mounted on a vehicle (not shown), that is, a diesel engine. The internal combustion engine 1 is provided with an exhaust manifold 12 that collects exhaust gas discharged from each cylinder 11.

排気管２は、排気マニホールド１２に接続され、排気マニホールド１２からの排ガスを下流方向（矢印Ｇで示す方向）に流して大気に放出する管である。 The exhaust pipe 2 is a pipe that is connected to the exhaust manifold 12 and causes the exhaust gas from the exhaust manifold 12 to flow in the downstream direction (the direction indicated by the arrow G) to be released to the atmosphere.

より詳しくは、この排気管２は、後処理ユニット３の上流側に位置する上流側排気管２１と、後処理ユニット３の下流側に位置する下流側排気管２２とからなる。上流側排気管２１は、その下流側端部にフランジ２１ａを有し、下流側排気管２２は、その上流側端部にフランジ２２ａを有する。 More specifically, the exhaust pipe 2 includes an upstream exhaust pipe 21 located upstream of the post-treatment unit 3 and a downstream exhaust pipe 22 located downstream of the post-treatment unit 3. The upstream exhaust pipe 21 has a flange 21a at its downstream end, and the downstream exhaust pipe 22 has a flange 22a at its upstream end.

次に、後処理ユニット３について説明する。後処理ユニット３の前後左右方向を図１に示す。なお、図示する後処理ユニット３の前後左右方向は、車両の前後左右方向とは無関係であり、説明の便宜上定められたものに過ぎない。本実施形態では、内燃機関１が車両に縦置きされており、後処理ユニット３の左方向が車両の前方向に一致する。 Next, the post-processing unit 3 will be described. The front-back, left-right direction of the post-processing unit 3 is shown in FIG. The front-rear and left-right directions of the illustrated post-processing unit 3 are irrelevant to the front-rear, left-right directions of the vehicle, and are merely defined for convenience of description. In the present embodiment, the internal combustion engine 1 is vertically installed in the vehicle, and the left direction of the post-processing unit 3 corresponds to the front direction of the vehicle.

後処理ユニット３は、排ガス入口管３１と、排ガス出口管３２と、少なくとも一つの触媒１０を内設する第１触媒ケーシング３３と、ＮＯｘ触媒１０ｃを内設する第２触媒ケーシング３４と、第１触媒ケーシング３３と第２触媒ケーシング３４とを連結する連結管３５と、尿素水を添加する添加弁３６を備える。また、後処理ユニット３は、概ね左右対称の構造を有する。 The aftertreatment unit 3 includes an exhaust gas inlet pipe 31, an exhaust gas outlet pipe 32, a first catalyst casing 33 in which at least one catalyst 10 is installed, a second catalyst casing 34 in which the NOx catalyst 10c is installed, and a first catalyst casing 34. A connection pipe 35 that connects the catalyst casing 33 and the second catalyst casing 34 and an addition valve 36 that adds urea water are provided. In addition, the post-processing unit 3 has a substantially symmetrical structure.

排ガス入口管３１は、後処理ユニット３の前端部且つ左側に配置され、前方から後方に延び、その前端は、上流側排気管２１の下流端に接続される。また、排ガス出口管３２は、後処理ユニット３の前端部且つ右側に配置され、前方から後方に延び、その前端は、下流側排気管２２の上流端に接続される。 The exhaust gas inlet pipe 31 is arranged at the front end portion and the left side of the aftertreatment unit 3, extends from the front to the rear, and the front end thereof is connected to the downstream end of the upstream exhaust pipe 21. Further, the exhaust gas outlet pipe 32 is arranged at the front end portion and the right side of the aftertreatment unit 3, extends from the front to the rear, and the front end thereof is connected to the upstream end of the downstream side exhaust pipe 22.

より詳しくは、排ガス入口管３１の上流側端部には、フランジ３１ａが設けられ、このフランジ３１ａに上流側排気管２１のフランジ２１ａが接続される。また同様に、排ガス出口管３２の下流側端部には、フランジ３２ａが設けられ、このフランジ３２ａに下流側排気管２２のフランジ２２ａが接続される。互いに接続されるフランジ同士は、ボルト（不図示）等の締結手段で取り外し可能に固定される。 More specifically, a flange 31a is provided at the upstream end of the exhaust gas inlet pipe 31, and the flange 21a of the upstream exhaust pipe 21 is connected to this flange 31a. Similarly, a flange 32a is provided at the downstream end of the exhaust gas outlet pipe 32, and the flange 22a of the downstream exhaust pipe 22 is connected to this flange 32a. The flanges connected to each other are detachably fixed by fastening means such as bolts (not shown).

第１触媒ケーシング３３は、管状に形成され、排ガス入口管３１から後方に向けて延在すると共に、後端部に位置する下流側端部３３ａの右側面に第１側孔３３ｂを有する。また、第１触媒ケーシング３３には、上流側に位置する排ガス入口管３１および下流側に位置する連結管３５よりも拡径された第１拡径部３３ｃが形成される。 The first catalyst casing 33 is formed in a tubular shape, extends rearward from the exhaust gas inlet pipe 31, and has a first side hole 33b on the right side surface of the downstream end 33a located at the rear end. Further, the first catalyst casing 33 is formed with a first expanded diameter portion 33c having a diameter larger than that of the exhaust gas inlet pipe 31 located on the upstream side and the connecting pipe 35 located on the downstream side.

第１触媒ケーシング３３は、第１拡径部３３ｃの位置にて、第１断熱緩衝部材（マット）３７を介して、上流側から酸化触媒（ＤＯＣ：Diesel Oxidation Catalyst）１０ａおよびパティキュレートフィルタ（以下「ＤＰＦ」という）１０ｂを内設する。 In the first catalyst casing 33, the oxidation catalyst (DOC: Diesel Oxidation Catalyst) 10a and the particulate filter (hereinafter referred to as “DOC”) are provided from the upstream side through the first heat insulating cushioning member (mat) 37 at the position of the first expanded diameter portion 33c. A "DPF") 10b is internally provided.

酸化触媒１０ａは、排ガス中の未燃成分（炭化水素ＨＣおよび一酸化炭素ＣＯ）を酸化して浄化する。酸化触媒１０ａは、ＨＣ，ＣＯの酸化時に生じた熱で排ガスを加熱、昇温する機能を有する。また酸化触媒１０ａは、排ガス中のＮＯをＮＯ2に酸化し、排ガス中のＮＯ2濃度を高める機能をも有する。 The oxidation catalyst 10a oxidizes and purifies unburned components (hydrocarbon HC and carbon monoxide CO) in the exhaust gas. The oxidation catalyst 10a has a function of heating and raising the temperature of exhaust gas by heat generated during the oxidation of HC and CO. The oxidation catalyst 10a oxidizes NO in the exhaust gas to NO 2, also has a function of increasing the NO 2 concentration in the exhaust gas.

ＤＰＦ１０ｂは、排ガス中に含まれる粒子状物質（ＰＭ：Particulate Matter）を捕集して除去するものである。ＤＰＦ１０ｂは、本実施形態では、ハニカム形状の耐熱性基材の両端開口を互い違いに市松状に閉塞した所謂ウォールフロータイプのものが用いられている。しかしながら、網の目構造のフォーム形状のもの等、ＰＭを物理的に捕集するあらゆるタイプのフィルタを用いることができる。 The DPF 10b collects and removes particulate matter (PM: Particulate Matter) contained in the exhaust gas. In the present embodiment, the DPF 10b is a so-called wall flow type in which openings at both ends of a honeycomb-shaped heat-resistant substrate are alternately closed in a checkered pattern. However, any type of filter that physically traps PM can be used, such as a mesh-form foam shape.

ＤＰＦ１０ｂは、その内壁にＰｔ等の貴金属（触媒）を担持させた所謂連続再生式の触媒付きＤＰＦからなる。この場合、エンジンの通常運転中、ＤＰＦ１０ｂに供給された排ガス中のＨＣが触媒作用で酸化、燃焼し、このとき同時にＤＰＦ１０ｂ内部に堆積しているＰＭが燃焼除去される。なお、ＤＰＦ１０ｂが触媒を有するため、ここではＤＰＦ１０ｂも本発明にいう触媒１０に含ませるものとする。 The DPF 10b is a so-called continuous regeneration type DPF with a catalyst having an inner wall supporting a noble metal (catalyst) such as Pt. In this case, during normal operation of the engine, HC in the exhaust gas supplied to the DPF 10b is catalytically oxidized and burned, and at the same time, PM accumulated inside the DPF 10b is burned and removed. Since the DPF 10b has a catalyst, the DPF 10b is also included in the catalyst 10 in the present invention here.

第２触媒ケーシング３４は、管状に形成され、排ガス出口管３２から後方に向けて延在すると共に、後端部に位置する上流側端部３４ａの左側面に第２側孔３４ｂを有する。また、第２触媒ケーシング３４には、上流側に位置する排ガス入口管３１および下流側に位置する排ガス出口管３２よりも拡径された第２拡径部３４ｃが形成される。 The second catalyst casing 34 is formed in a tubular shape, extends rearward from the exhaust gas outlet pipe 32, and has a second side hole 34b on the left side surface of the upstream end 34a located at the rear end. In addition, the second catalyst casing 34 is formed with a second expanded diameter portion 34c having a diameter larger than that of the exhaust gas inlet pipe 31 located on the upstream side and the exhaust gas outlet pipe 32 located on the downstream side.

第２触媒ケーシング３４は、第２拡径部３４ｃの位置にて、第２断熱緩衝部材（マット）３８を介して、上流側からＮＯｘ触媒１０ｃおよびアンモニア酸化触媒１０ｄを内設する。 In the second catalyst casing 34, the NOx catalyst 10c and the ammonia oxidation catalyst 10d are internally provided from the upstream side via the second heat insulating cushioning member (mat) 38 at the position of the second expanded diameter portion 34c.

ＮＯｘ触媒１０ｃは、排ガス中の窒素酸化物ＮＯｘを浄化するための触媒である。ＮＯｘ触媒１０ｃは、選択還元型ＮＯｘ触媒（ＳＣＲ：Selective Catalytic Reduction）からなり、尿素水から加水分解されて生成されたアンモニア（ＮＨ3）によって、ＮＯｘを連続的に還元し得る。 The NOx catalyst 10c is a catalyst for purifying nitrogen oxide NOx in the exhaust gas. The NOx catalyst 10c is composed of a selective reduction type NOx catalyst (SCR: Selective Catalytic Reduction), and can continuously reduce NOx by ammonia (NH 3 ) generated by hydrolysis of urea water.

アンモニア酸化触媒１０ｄは、ＮＯｘ触媒１０ｃでＮＯｘの還元に消費されなかった余剰のアンモニア（ＮＨ3）を酸化して、Ｎ2を生成する触媒である。 The ammonia oxidation catalyst 10d is a catalyst that oxidizes excess ammonia (NH 3 ) that has not been consumed by the NOx catalyst 10c for NOx reduction to generate N 2 .

本実施形態においては、第１触媒ケーシング３３と第２触媒ケーシング３４とは、互いに並列して左右に配置される。また、第１側孔３３ｂと第２側孔３４ｄとは、互いに対向する位置に配置される。 In the present embodiment, the first catalyst casing 33 and the second catalyst casing 34 are arranged side by side in parallel with each other. Further, the first side hole 33b and the second side hole 34d are arranged at positions facing each other.

連結管３５は、左右方向における第１触媒ケーシング３３と第２触媒ケーシング３４との間の位置に配置され、第１触媒ケーシング３３の下流端Ｘ１と第２触媒ケーシング３４の上流端Ｙ１とを連結する。また、連結管３５は、排気流れ方向に沿って後方から前方に向かって延び、Ｕ字状に折り返されて後方に延びる折り返し部分Ｕを有する。 The connecting pipe 35 is arranged at a position between the first catalyst casing 33 and the second catalyst casing 34 in the left-right direction, and connects the downstream end X1 of the first catalyst casing 33 and the upstream end Y1 of the second catalyst casing 34. To do. The connecting pipe 35 has a folded-back portion U that extends from the rear to the front along the exhaust flow direction, is folded back in a U-shape, and extends rearward.

より詳しくは、連結管３５は、第１側孔３３ｂから第２側孔３４ｂ側（図示右側）に向かって延び、前方に折れ曲がる第１部分３５ａと、第２側孔３４ｂから第１側孔３３ｂ側（図示左側）に向かって延び、前方に折れ曲がる第２部分３５ｂとを有する。具体的には、第１部分３５ａは、図中の第１側孔３３ｂからＸ２までの部分に該当し、第２部分３５ｂは、図中の第２側孔３４ｂからＹ２までの部分に該当する。 More specifically, the connecting pipe 35 extends from the first side hole 33b toward the second side hole 34b (right side in the drawing) and bends forward, and the first portion 35a and the second side hole 34b to the first side hole 33b. The second portion 35b extends toward the side (left side in the drawing) and is bent forward. Specifically, the first portion 35a corresponds to a portion from the first side hole 33b to X2 in the drawing, and the second portion 35b corresponds to a portion from the second side hole 34b to Y2 in the drawing. ..

また、連結管３５は、第１部分３５ａの下流端Ｘ２から前方に延びると共に、折り返し部分Ｕで折り返されて後方に延び、第２部分３５ｂの上流端Ｙ２に接続される第３部分３５ｃを有する。すなわち、連結管３５がこのようにＵ字状に折り返されて形成されることで、第１側孔３３ｂと第２側孔３４ｄを直線的に結ぶよりも、連結管３５の管長が長くなる。 Further, the connecting pipe 35 has a third portion 35c extending forward from the downstream end X2 of the first portion 35a, folded back at the folding portion U and extending rearward, and connected to the upstream end Y2 of the second portion 35b. .. That is, since the connecting pipe 35 is formed by folding back in the U-shape in this way, the pipe length of the connecting pipe 35 becomes longer than that of connecting the first side hole 33b and the second side hole 34d linearly.

ケーシング４は、ステンレス等の耐熱材料を用いた箱型ケーシングからなり、後処理ユニット３全体を略気密に覆う。ケーシング４の内周面上ほぼ全体には、後処理ユニット３の保温のため、グラスウール等の断熱材４１が敷設される。 The casing 4 is a box-shaped casing made of a heat-resistant material such as stainless steel, and covers the entire post-treatment unit 3 in a substantially airtight manner. A heat insulating material 41 such as glass wool is laid on almost the entire inner peripheral surface of the casing 4 for keeping the temperature of the post-treatment unit 3.

ケーシング４の前面４２には、左右の位置に、後処理ユニット３の排ガス入口管３１が挿通される入口孔４２ａと、排ガス出口管３２が挿通される出口孔４２ｂとが形成される。 An inlet hole 42a through which the exhaust gas inlet pipe 31 of the post-treatment unit 3 is inserted and an outlet hole 42b through which the exhaust gas outlet pipe 32 is inserted are formed at the left and right positions on the front surface 42 of the casing 4.

他方、ケーシング４の後面４３には、第１部分３５ａの折れ曲がり部分Ｌの後方に位置する部分に、添加弁３６を取り付ける取付部４３ａが形成される。取付部４３ａは、前方に凹んで形成され、その前端には、前後方向に延びる外側挿通孔４３ｂが形成される。また、折れ曲がり部分Ｌの後端面には、外側挿通孔４３ｂと同軸に内側挿通孔３５ｄが形成されている。添加弁３６は、ケーシング４の外部（後方）から外側挿通孔４３ｂと内側挿通孔３５ｄの両方に挿通され、取付部４３ａに設けられたボス部４３ｃによって、ケーシング４に固定される。 On the other hand, on the rear surface 43 of the casing 4, a mounting portion 43a for mounting the addition valve 36 is formed at a portion located behind the bent portion L of the first portion 35a. The mounting portion 43a is formed so as to be recessed forward, and an outer insertion hole 43b extending in the front-rear direction is formed at the front end thereof. Further, an inner insertion hole 35d is formed on the rear end surface of the bent portion L coaxially with the outer insertion hole 43b. The addition valve 36 is inserted into both the outer insertion hole 43b and the inner insertion hole 35d from the outside (rear) of the casing 4, and is fixed to the casing 4 by a boss portion 43c provided in the attachment portion 43a.

添加弁３６は、折り返し部分Ｕの上流側から折り返し部分Ｕに向かって、後方から前方に尿素水を添加するように配置される。ここでいう折り返し部分Ｕの上流側とは、第１部分３５ａの折れ曲がり部分Ｌ内を意味する。 The addition valve 36 is arranged so as to add the urea water from the rear side to the front side from the upstream side of the folded-back portion U toward the folded-back portion U. The upstream side of the folded-back portion U means the inside of the bent portion L of the first portion 35a.

詳しくは後述するが、折り返し部分Ｕの前面部Ｕｆの内表面には、添加された尿素水が液相状態で滞留する傾向にある。尿素水が滞留する部位は、その尿素水に起因して腐食する虞があるため、本実施形態においては、この前面部Ｕｆを着脱可能にして交換できるようにする。 As will be described later in detail, the added urea water tends to stay in the liquid phase on the inner surface of the front surface portion Uf of the folded portion U. Since the area where urea water is retained may be corroded due to the urea water, in the present embodiment, the front surface portion Uf is made detachable and can be replaced.

具体的には、前面部Ｕｆは、上下且つ左右方向に延びる分割面Ｓに沿って連結管３５から分割される。便宜上、前面部Ｕｆを除く連結管３５の部分を連結管本体Ｂという。前面部Ｕｆは、前方から見て楕円ないし長円形状を成す。この分割面Ｓの位置は任意であるが、前面部Ｕｆは、尿素水が液相状態で滞留する部位、ひいてはその尿素水に起因して腐食する虞がある部位を含むように設定される。本実施形態においては、上流側から下流側に向かうにつれ折り返し部分Ｕが約９０°曲がり、且つ、折り返し部分Ｕの管路中心Ｃ上の位置に、分割面Ｓが設定される。 Specifically, the front surface portion Uf is divided from the connecting pipe 35 along a division surface S that extends in the vertical and horizontal directions. For convenience, the portion of the connecting pipe 35 excluding the front surface portion Uf is referred to as a connecting pipe body B. The front surface portion Uf has an elliptical or oval shape when viewed from the front. The position of the dividing surface S is arbitrary, but the front surface portion Uf is set so as to include a portion where urea water is retained in a liquid phase state, and thus a portion which may be corroded due to the urea water. In the present embodiment, the folded-back portion U bends about 90° from the upstream side to the downstream side, and the dividing surface S is set at a position on the conduit center C of the folded-back portion U.

前面部Ｕｆの後端部と、残りの連結管本体Ｂの前端部には、それぞれフランジ３９ａ，フランジ３９ｂが設けられ、互いのフランジ３９ａ，３９ｂがボルト３９ｃ等の締結手段で取り外し可能に固定される。フランジ３９ａ，３９ｂが固定された状態では、前面部Ｕｆと連結管本体Ｂが気密に接続される。 A flange 39a and a flange 39b are respectively provided at the rear end of the front surface portion Uf and the front end of the remaining connecting pipe body B, and the flanges 39a and 39b are detachably fixed by fastening means such as bolts 39c. It When the flanges 39a and 39b are fixed, the front surface portion Uf and the connecting pipe body B are hermetically connected.

反対に、フランジ３９ａ，３９ｂによる固定が解除されると、前面部Ｕｆは、連結管本体Ｂから取り外し可能となる。 On the contrary, when the fixing by the flanges 39a and 39b is released, the front surface portion Uf can be removed from the connecting pipe body B.

ケーシング４の前面４２の中央部には、折り返し部分Ｕの前面部Ｕｆに対向する位置に、前端部Ｕｆが通過可能な開口部４４が設けられる。 An opening 44, through which the front end Uf can pass, is provided in a central portion of the front surface 42 of the casing 4 at a position facing the front surface Uf of the folded-back portion U.

開口部４４の面積は任意であるが、前面部Ｕｆの交換作業が容易に行える大きさにすることが好ましい。また、開口部４４の形状は任意であり、例えば円形や正方形とすることが考えられるが、前面部Ｕｆの形状に合わせて、左右方向に長い長方形としても良い。 Although the area of the opening 44 is arbitrary, it is preferable that the opening 44 has a size such that the front surface Uf can be easily replaced. Further, the shape of the opening 44 is arbitrary, and for example, a circular shape or a square shape can be considered, but it may be a rectangular shape that is long in the left-right direction in accordance with the shape of the front surface portion Uf.

ケーシング４の前面４２には、この開口部４４を前方から開閉可能に覆う蓋５が設けられる。この蓋５は、開口部４４の周囲において、複数のボルト４５等の締結手段によって、ケーシング４の前面４２に取り外し可能に固定される。なお、後処理ユニット３の保温のため、蓋５の内表面にも、グラスウール等の断熱材４１が敷設される。 The front surface 42 of the casing 4 is provided with a lid 5 that covers the opening 44 so as to be opened and closed from the front. The lid 5 is detachably fixed to the front surface 42 of the casing 4 around the opening 44 by fastening means such as a plurality of bolts 45. A heat insulating material 41 such as glass wool is laid on the inner surface of the lid 5 in order to keep the temperature of the post-treatment unit 3.

なお、本発明における後処理ユニット３の管部材には、ＮＯｘ触媒１０ｃの上流側に位置する全ての管状部材が含まれる。すなわち、ＮＯｘ触媒１０ｃの上流側に位置する第２触媒ケーシング３４と、連結管３５と、第１触媒ケーシング３３と、排ガス入口管３１とが、本発明の管部材に含まれる。本実施形態における管部材は、このうちの連結管３５である。 The tubular members of the post-treatment unit 3 in the present invention include all tubular members located upstream of the NOx catalyst 10c. That is, the second catalyst casing 34 located upstream of the NOx catalyst 10c, the connecting pipe 35, the first catalyst casing 33, and the exhaust gas inlet pipe 31 are included in the pipe member of the present invention. The pipe member in the present embodiment is the connecting pipe 35 among them.

次に、図１に基づいて、本実施形態に係る排ガス浄化装置１００の作用効果を説明する。 Next, the operation and effect of the exhaust gas purifying apparatus 100 according to the present embodiment will be described based on FIG.

内燃機関１の排ガスは、排気マニホールド１２から上流側排気管２１を通過し、排ガス入口管３１を通じて、第１触媒ケーシング３３内へ流入する。 The exhaust gas of the internal combustion engine 1 passes from the exhaust manifold 12 through the upstream exhaust pipe 21, and flows into the first catalyst casing 33 through the exhaust gas inlet pipe 31.

第１触媒ケーシング３３内へ流入した排ガスは、酸化触媒１０ａを通過し、これにより、排ガス中の未燃成分（炭化水素ＨＣおよび一酸化炭素ＣＯ）が酸化して浄化される。 The exhaust gas flowing into the first catalyst casing 33 passes through the oxidation catalyst 10a, whereby unburned components (hydrocarbons HC and carbon monoxide CO) in the exhaust gas are oxidized and purified.

次に、酸化触媒１０ａを通過した排ガスは、ＤＰＦ１０ｂに流入し、ＤＰＦ１０ｂによって排ガス中に含まれる粒子状物質（ＰＭ）が捕集除去される。 Next, the exhaust gas that has passed through the oxidation catalyst 10a flows into the DPF 10b, and the DPF 10b collects and removes particulate matter (PM) contained in the exhaust gas.

ＤＰＦ１０ｂを通過した排ガスは、第１触媒ケーシング３３の後端部に位置する第１側孔３３ｂから連結管３５の第１部分３５ａに流れ、第１部分３５ａの折れ曲がり形状に沿って前方へ９０°方向転換して、第３部分３５ｃへ流れる。 The exhaust gas that has passed through the DPF 10b flows from the first side hole 33b located at the rear end of the first catalyst casing 33 to the first portion 35a of the connecting pipe 35, and moves forward by 90° along the bent shape of the first portion 35a. It turns and flows to the third portion 35c.

第３部分３５ｃへ流れた排ガスは、折り返し部分Ｕにて後方へ１８０°方向転換し、後方の第２部分３５ｂへ流れ、第２部分の折れ曲がり形状に沿って９０°方向転換し、第２側孔３４ｂを通じて第２触媒ケーシング３４内へ流入する。 The exhaust gas that has flowed to the third portion 35c turns 180° rearward at the turnback portion U, flows to the rear second portion 35b, and turns 90° along the bent shape of the second portion, and then turns to the second side. It flows into the second catalyst casing 34 through the hole 34b.

ここで、第１部分３５ａの折れ曲がり部分Ｌに配置された添加弁３６は、第３部分３５ｃの折り返し部分Ｕに向かって、後方から前方に尿素水を添加する。尿素水が混合された排ガスは、折り返し部分Ｕにて後方へ１８０°方向転換し、後方の第２部分３５ｂへ流れ、第２部分３５ｂの折れ曲がり形状に沿って９０°方向転換し、第２側孔３４ｂを通じて第２触媒ケーシング３４内へ流入する。この過程で、添加弁３６から添加された尿素水は、排ガスと混合して蒸発しつつ、加水分解されてアンモニアを生成する。 Here, the addition valve 36 arranged in the bent portion L of the first portion 35a adds urea water from the rear to the front toward the folded portion U of the third portion 35c. The exhaust gas mixed with the urea water turns 180° backward at the turn-back portion U, flows to the second portion 35b at the back, turns 90° along the bent shape of the second portion 35b, and turns to the second side. It flows into the second catalyst casing 34 through the hole 34b. In this process, the urea water added from the addition valve 36 mixes with the exhaust gas and evaporates, and is hydrolyzed to generate ammonia.

次に、第２触媒ケーシング３４内において、尿素水とアンモニアの少なくとも一方を含む排ガスは、ＮＯｘ触媒１０ｃを通過する。このとき、ＮＯｘ触媒１０ｃは、尿素水が加水分解されて生成されたアンモニアによって、ＮＯｘを還元する。 Next, in the second catalyst casing 34, the exhaust gas containing at least one of urea water and ammonia passes through the NOx catalyst 10c. At this time, the NOx catalyst 10c reduces NOx by the ammonia generated by hydrolysis of the urea water.

ＮＯｘ触媒１０ｃでＮＯｘの還元に消費されなかった余剰のアンモニアは、アンモニア酸化触媒１０ｄと接触して酸化され、大気への放出が抑制される。 Excess ammonia that has not been consumed by the NOx catalyst 10c for NOx reduction contacts the ammonia oxidation catalyst 10d, is oxidized, and is suppressed from being released into the atmosphere.

アンモニア酸化触媒１０ｄを通過した排ガスは、排ガス出口管３２を通じて下流側排気管２２へ排出されて、下流側排気管２２から大気に放出される。 The exhaust gas that has passed through the ammonia oxidation catalyst 10d is discharged to the downstream side exhaust pipe 22 through the exhaust gas outlet pipe 32, and is discharged from the downstream side exhaust pipe 22 to the atmosphere.

上記の作用のうち、酸化触媒１０ａ、ＤＰＦ１０ｂ、ＮＯｘ触媒１０ｃ、およびアンモニア酸化触媒１０ｄに関しては、その触媒温度（触媒床温）が活性温度域にあるときに、排ガス浄化作用を有効に発揮する。よって、各触媒１０の温度をできるだけ高温に保持するのが有効である。 Among the above actions, the oxidation catalyst 10a, the DPF 10b, the NOx catalyst 10c, and the ammonia oxidation catalyst 10d effectively exhibit the exhaust gas purification action when the catalyst temperature (catalyst bed temperature) is in the activation temperature range. Therefore, it is effective to keep the temperature of each catalyst 10 as high as possible.

本実施形態においては、内周面に断熱材４１を敷設したケーシング４内に、後処理ユニット３を収容することで、後処理ユニット３が外気や走行風で冷却されるのを抑制し、各触媒１０の温度を高温に保持することができる。 In the present embodiment, the post-treatment unit 3 is housed in the casing 4 having the heat insulating material 41 laid on the inner peripheral surface thereof, so that the post-treatment unit 3 is prevented from being cooled by outside air or traveling wind. The temperature of the catalyst 10 can be kept high.

本実施形態の後処理ユニット３においては、連結管３５がＵ字状に折り返されて形成されている。このため、連結管３５を直線的に形成するよりも、連結管３５の管長を長くし、且つ、後処理ユニット３をコンパクトに構成することができる。 In the post-processing unit 3 of the present embodiment, the connecting pipe 35 is formed by folding back in a U-shape. For this reason, the pipe length of the connecting pipe 35 can be made longer and the post-processing unit 3 can be made more compact than when the connecting pipe 35 is formed linearly.

また、添加弁３６から添加された尿素水が、この長く且つ折り返されて形成された連結管３５を通過することで、尿素水が排ガスとの間で十分に攪拌混合されて蒸発され、尿素水の加水分解が促進される。この結果、アンモニアが効率よく生成されて、ＮＯｘ触媒１０ｃにおけるＮＯｘ浄化率の向上に有利となる。 Further, the urea water added from the addition valve 36 passes through the long and folded connecting pipe 35, whereby the urea water is sufficiently stirred and mixed with the exhaust gas to be evaporated, Hydrolysis is accelerated. As a result, ammonia is efficiently produced, which is advantageous for improving the NOx purification rate of the NOx catalyst 10c.

一方、尿素水を含む排ガスが折り返し部分Ｕを通過するとき、尿素水が前面部Ｕｆの内表面に液相状態で付着して滞留する傾向にある。特に、この折り返し部分Ｕでは、尿素水が１８０°方向転換する際に遠心力を受け、内表面に尿素水が付着、滞留する傾向にある。この結果、前面部Ｕｆは、滞留した尿素水に起因して、内表面から腐食していく虞がある。 On the other hand, when the exhaust gas containing the urea water passes through the turn-back portion U, the urea water tends to adhere to and stay in the inner surface of the front surface portion Uf in a liquid phase state. In particular, in the folded-back portion U, when the urea water is turned by 180°, a centrifugal force is applied, and the urea water tends to adhere and stay on the inner surface. As a result, the front surface portion Uf may be corroded from the inner surface due to the retained urea water.

なお、近年のＮＯｘ規制強化に対応するためには、ＮＯｘ触媒の大型化と尿素水添加量の増加が必要となるので、滞留部位がより著しく腐食する可能性がある。 In order to cope with the recent tightening of NOx regulations, it is necessary to increase the size of the NOx catalyst and increase the amount of urea water added, so that the retention area may be significantly corroded.

そこで、本実施形態に係る排ガス浄化装置１００においては、尿素水の滞留に起因して腐食する虞がある前面部Ｕｆを、連結管３５から着脱可能とする。更に、ケーシング４の前面４２には、その取り外された前面部Ｕｆが通過可能な開口部４４を設けると共に、その開口部４４を開閉可能に覆う蓋５を設ける。 Therefore, in the exhaust gas purifying apparatus 100 according to the present embodiment, the front surface portion Uf, which may be corroded due to the retention of the urea water, is detachable from the connecting pipe 35. Further, the front surface 42 of the casing 4 is provided with an opening portion 44 through which the removed front surface portion Uf can pass, and a lid 5 that covers the opening portion 44 so as to be openable and closable.

これにより、後処理ユニット３がケーシング４内に収容された状態のまま、腐食した前面部Ｕｆを容易に交換することが可能になる。 As a result, the corroded front surface portion Uf can be easily replaced while the post-treatment unit 3 is accommodated in the casing 4.

この交換作業の際には、先ず、ケーシング４の前面４２のボルト４５を緩めて、蓋５を取り外し、ケーシング４の開口部４４から手や工具等を差し込んで、前面部Ｕｆのボルト３９ｃを緩めて、フランジ３９ａ，３９ｂによる固定を解除し、前面部Ｕｆを連結管３５から取り外す。そして、交換用の前面部Ｕｆを取り外し手順と逆の手順で取り付ける。このように、本実施形態においては、後処理ユニット３がケーシング４に収容されたままの状態でも、交換作業を容易に行うことができる。 In this replacement work, first, the bolts 45 on the front surface 42 of the casing 4 are loosened, the lid 5 is removed, and a hand, a tool or the like is inserted from the opening 44 of the casing 4 to loosen the bolts 39c of the front surface portion Uf. Then, the fixing by the flanges 39a and 39b is released, and the front surface portion Uf is removed from the connecting pipe 35. Then, the front part Uf for replacement is attached in the reverse order of the removal procedure. As described above, in the present embodiment, the replacement work can be easily performed even when the post-processing unit 3 is still accommodated in the casing 4.

また、本実施形態においては、ケーシング４の開口部４４が前面部Ｕｆに対向する位置にあるので、交換作業をより簡単に行うことが可能になる。 Further, in the present embodiment, since the opening 44 of the casing 4 is located at a position facing the front surface portion Uf, the replacement work can be performed more easily.

なお、本発明は、上述の実施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、適宜変形して実施することが可能である。 It should be noted that the present invention is not limited to the above-described embodiments, and can be appropriately modified and carried out without departing from the spirit of the present invention.

１ 内燃機関
２ 排気管
３ 後処理ユニット
４ ケーシング
５ 蓋
１０ｃ 選択還元型ＮＯｘ触媒
３１ 排ガス入口管
３２ 排ガス出口管
３３ 第１触媒ケーシング
３４ 第２触媒ケーシング
３５ 連結管
３６ 添加弁
４４ 開口部
１００ 排ガス浄化装置 1 Internal Combustion Engine 2 Exhaust Pipe 3 Post-treatment Unit 4 Casing 5 Lid 10c NOx Catalyst for Selective Reduction 31 Exhaust Gas Inlet Pipe 32 Exhaust Gas Outlet Pipe 33 First Catalyst Casing 34 Second Catalyst Casing 35 Connection Pipe 36 Addition Valve 44 Opening 100 Exhaust Gas Purification apparatus

Claims (2)

排気管と、
前記排気管の途中に設けられ、排ガスを浄化するための複数の触媒を有する後処理ユニットと、
前記後処理ユニットを収容するケーシングと、を備え、
前記後処理ユニットは、
選択還元型ＮＯｘ触媒と、
前記選択還元型ＮＯｘ触媒の上流側から選択還元型ＮＯｘ触媒に向かって延び、排ガスが通過される管部材と、
前記管部材内における前記選択還元型ＮＯｘ触媒の上流側の位置に尿素水を添加する添加弁と、を備え、
前記管部材は、折り返すことで排ガスの流れの向きが変わる折り返し部分を有し、
前記添加弁は、前記折り返し部分に向かって尿素水を噴射し、
前記折り返し部分は、着脱可能とされ、
前記ケーシングは、前記折り返し部分に対向する位置に形成され、前記折り返し部分が通過可能な開口部と、前記開口部を開閉可能に覆う蓋と、を有する
ことを特徴とする内燃機関の排ガス浄化装置。 Exhaust pipe,
An aftertreatment unit provided in the middle of the exhaust pipe and having a plurality of catalysts for purifying exhaust gas,
A casing accommodating the post-treatment unit,
The post-processing unit,
A selective reduction type NOx catalyst,
A pipe member that extends from the upstream side of the selective reduction type NOx catalyst toward the selective reduction type NOx catalyst and through which exhaust gas passes,
An addition valve for adding urea water to a position on the upstream side of the selective reduction type NOx catalyst in the pipe member,
The pipe member has a folded portion in which the direction of the flow of the exhaust gas is changed by folding it.
The addition valve injects urea water toward the folded portion,
The folded-back portion is detachable,
The casing, the formed at a position facing the folded portion, the folded portion and the opening portion can pass, the exhaust gas purifying apparatus for an internal combustion engine and having a, a lid for covering openably the opening .. 排気管と、
前記排気管の途中に設けられ、排ガスを浄化するための複数の触媒を有する後処理ユニットと、
前記後処理ユニットを収容するケーシングと、を備え、
前記後処理ユニットは、
少なくとも一つの触媒を内設する管状の第１触媒ケーシングと、
前記第１触媒ケーシングに並列して配置され、選択還元型ＮＯｘ触媒を内設する管状の第２触媒ケーシングと、
前記第１触媒ケーシングと前記第２触媒ケーシングとの間の位置に配置され、前記第１触媒ケーシングの下流端と前記第２触媒ケーシングの上流端とを連結する連結管と、
前記連結管内に尿素水を添加する添加弁と、を備え、
前記連結管は、折り返すことで排ガスの流れの向きが変わる折り返し部分を有し、
前記添加弁は、前記折り返し部分に向かって尿素水を噴射し、
前記折り返し部分は、着脱可能とされ、
前記ケーシングは、前記折り返し部分に対向する位置に形成され、前記折り返し部分が通過可能な開口部と、前記開口部を開閉可能に覆う蓋と、を有する
ことを特徴とする内燃機関の排ガス浄化装置。 Exhaust pipe,
An aftertreatment unit provided in the middle of the exhaust pipe and having a plurality of catalysts for purifying exhaust gas,
A casing accommodating the post-treatment unit,
The post-processing unit,
A tubular first catalyst casing containing at least one catalyst therein;
A tubular second catalyst casing that is arranged in parallel with the first catalyst casing and internally houses the selective reduction type NOx catalyst;
A connecting pipe arranged at a position between the first catalyst casing and the second catalyst casing and connecting a downstream end of the first catalyst casing and an upstream end of the second catalyst casing ;
An addition valve for adding urea water in the connecting pipe ,
The connecting pipe has a folded portion in which the direction of the flow of exhaust gas is changed by folding it.
The addition valve injects urea water toward the folded portion,
The folded portion is detachable,
The casing, the formed at a position facing the folded portion, the folded portion and the opening portion can pass, the exhaust gas purifying apparatus for an internal combustion engine and having a, a lid for covering openably the opening ..
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