JP2019065782A - Exhaust emission control device for internal combustion engine - Google Patents

Exhaust emission control device for internal combustion engine Download PDF

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JP2019065782A
JP2019065782A JP2017193019A JP2017193019A JP2019065782A JP 2019065782 A JP2019065782 A JP 2019065782A JP 2017193019 A JP2017193019 A JP 2017193019A JP 2017193019 A JP2017193019 A JP 2017193019A JP 2019065782 A JP2019065782 A JP 2019065782A
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passage
exhaust gas
exhaust
internal combustion
combustion engine
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JP6981156B2 (en
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朝幸 伊藤
Tomoyuki Ito
朝幸 伊藤
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Isuzu Motors Ltd
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Isuzu Motors Ltd
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Priority to PCT/JP2018/035967 priority patent/WO2019069792A1/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

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  • Chemical Kinetics & Catalysis (AREA)
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  • Exhaust Gas After Treatment (AREA)

Abstract

To promote the mixture of injected urea water and exhaust gas.SOLUTION: An exhaust emission control device for an internal combustion engine includes an exhaust passage where exhaust gas from the internal combustion engine flows, a catalyst arranged in the exhaust passage, an injection valve 14 provided on the upstream side of the catalyst for injecting reductant into the exhaust passage, and a turn-back passage 30 provided inside the exhaust passage at a position on the downstream side of the injection valve and on the upstream side of the catalyst for turning back the flow of the exhaust gas from the forward flow direction to the back flow direction and then turning it back to the forward flow direction.SELECTED DRAWING: Figure 4

Description

本発明は内燃機関の排気浄化装置に係り、特に、ディーゼルエンジンに主に適用される排気浄化装置に関する。   The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, and more particularly to an exhaust gas purification apparatus mainly applied to a diesel engine.

ディーゼルエンジンの排気通路には、排気中のＮＯｘ（窒素酸化物）を還元除去する選択還元型ＮＯｘ触媒が設けられる。ＮＯｘ触媒の上流側には尿素水を噴射する噴射弁が設けられる。ＮＯｘ触媒は、尿素水を加水分解して得られるアンモニアＮＨ3とＮＯｘを反応させ、排気中のＮＯｘを窒素Ｎ2に還元する。 In the exhaust passage of the diesel engine, a selective reduction type NOx catalyst is provided which reduces and removes NOx (nitrogen oxide) in the exhaust gas. An injection valve for injecting urea water is provided upstream of the NOx catalyst. The NOx catalyst causes ammonia NH 3 obtained by hydrolyzing urea water to react with NOx to reduce NOx in the exhaust to nitrogen N 2 .

国際公開第２０１０／０５３０３３号International Publication No. 2010/053033 特開２００８−１４４６４４号公報JP 2008-144644 A 特開２００６−７７５７６号公報Unexamined-Japanese-Patent No. 2006-77576

ＮＯｘ触媒を高効率で作動させるには、尿素水の加水分解を促進し、尿素水の単位容量当たりのアンモニア生成量すなわちアンモニア生成効率をできるだけ高い水準に維持することが望ましい。そして尿素水の加水分解を促進するためには、排気通路内に噴射された尿素水と排気ガスの混合を可能な限り促進することが好ましい。   In order to operate the NOx catalyst with high efficiency, it is desirable to accelerate the hydrolysis of urea water and maintain the ammonia generation amount per unit volume of urea water, that is, the ammonia generation efficiency as high as possible. And in order to promote the hydrolysis of the urea water, it is preferable to promote the mixing of the urea water and the exhaust gas injected into the exhaust passage as much as possible.

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、噴射された尿素水と排気ガスの混合を促進できる内燃機関の排気浄化装置を提供することにある。   Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide an exhaust gas purification apparatus for an internal combustion engine capable of promoting the mixing of the injected urea water and the exhaust gas.

本発明の一の態様によれば、
内燃機関の排気ガスが流される排気通路と、
前記排気通路に配置された触媒と、
前記触媒の上流側に設けられ、前記排気通路内に還元剤を噴射する噴射弁と、
前記噴射弁の下流側かつ前記触媒の上流側の位置における前記排気通路の内部に設けられ、排気ガスの流れを順流方向から逆流方向に折り返し、その後順流方向に折り返すように構成された折り返し通路と、
を備えたことを特徴とする内燃機関の排気浄化装置が提供される。 According to one aspect of the invention,
An exhaust passage through which exhaust gas of an internal combustion engine flows;
A catalyst disposed in the exhaust passage;
An injection valve provided on the upstream side of the catalyst and injecting a reducing agent into the exhaust passage;
A return passage provided inside the exhaust passage at a position downstream of the injection valve and upstream of the catalyst, configured to turn the flow of the exhaust gas from the forward flow direction to the reverse flow direction, and thereafter to turn back in the forward flow direction; ,
An exhaust gas purification apparatus for an internal combustion engine is provided.

好ましくは、前記折り返し通路が、
前記排気通路内の周縁部を閉じると共に、上流側に向かって突出する連通管を有する閉鎖部材と、
前記連通管の入口部を上流側から隙間を隔てて覆うカバー部材と、
により画成される。 Preferably, the said return passage is
And a closing member having a communicating pipe projecting toward the upstream side while closing the peripheral portion in the exhaust passage.
A cover member that covers the inlet portion of the communication pipe with a gap from the upstream side;
Defined by

好ましくは、前記カバー部材が、先端側が上流側に向けられた先細り形状の部分を有する。   Preferably, the cover member has a tapered portion whose distal end is directed upstream.

好ましくは、前記先細り形状が円錐形状である。   Preferably, the tapered shape is conical.

好ましくは、前記連通管の前記入口部が、その周方向に分割された複数の分割片を有し、前記複数の分割片は、半径方向内側および外側へと交互に折曲されている。   Preferably, the inlet portion of the communication tube has a plurality of circumferentially divided split pieces, and the plurality of split pieces are alternately bent radially inward and outward.

好ましくは、前記排気通路が、半径方向内側に位置された内側排気通路と、前記内側排気通路の半径方向外側に隣接して位置され、前記内側排気通路を囲繞し、前記内側排気通路から排出された排気ガスを逆方向に流す外側排気通路とを含み、
前記折り返し通路が、前記内側排気通路内に配置される。 Preferably, the exhaust passage is located adjacent to the radially inner inner exhaust passage and radially outward of the inner exhaust passage, and surrounds the inner exhaust passage and is discharged from the inner exhaust passage. And an outer exhaust passage for flowing the exhaust gas in the reverse direction,
The turnaround passage is disposed in the inner exhaust passage.

好ましくは、前記噴射弁の下流側かつ前記折り返し通路の上流側の位置に設けられ、排気ガスの熱を蓄熱する蓄熱部材をさらに備える。   Preferably, the fuel cell system further includes a heat storage member provided downstream of the injection valve and upstream of the turnback passage for storing heat of exhaust gas.

好ましくは、前記蓄熱部材は、先端側が上流側に向けられた先細り形状の部分を有し、当該部分に複数の開口部を有する。   Preferably, the heat storage member has a tapered portion whose distal end is directed upstream, and has a plurality of openings in the portion.

本発明によれば、噴射された尿素水と排気ガスの混合を促進できる。   According to the present invention, the mixing of the injected urea water and the exhaust gas can be promoted.

本発明の第１実施形態に係る排気浄化装置の全体構造を示す縦断側面図である。BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal side view which shows the whole structure of the exhaust gas purification device which concerns on 1st Embodiment of this invention. 排気浄化装置の縦断後面図であり、図１のＩＩ−ＩＩ断面図である。It is a vertical rear elevation view of an exhaust gas purification device, and is an II-II sectional view of FIG. 排気浄化装置の縦断前面図であり、図１のＩＩＩ−ＩＩＩ断面図である。It is a longitudinal front view of an exhaust gas purification device, and is an III-III sectional view of FIG. 第２通路の内部の構成を示す縦断側面図である。It is a vertical side view which shows the structure inside the 2nd channel | path. 第２実施形態における第２通路の内部の構成を示す縦断側面図である。It is a vertical side view which shows the structure inside the 2nd channel | path in 2nd Embodiment. 第２実施形態に係る排気浄化装置の全体構造を示す縦断側面図である。It is a vertical side view showing the whole exhaust purification system concerning a 2nd embodiment. 第３実施形態における第２通路の内部の構成を示す縦断側面図である。It is a vertical side view which shows the structure inside the 2nd channel | path in 3rd Embodiment. 蓄熱部材の縦断前面図であり、図７のＶＩＩＩ−ＶＩＩＩ断面図である。It is a longitudinal front view of a thermal storage member, and is a VIII-VIII sectional view of FIG. 連通管の縦断前面図であり、図７のＩＸ−ＩＸ断面図である。It is a longitudinal front view of a communicating pipe, and is IX-IX sectional drawing of FIG. 分割片の断面図である。It is sectional drawing of a division | segmentation piece.

以下、添付図面を参照して本発明の実施形態を説明する。なお本発明は以下の実施形態に限定されない点に留意されたい。   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited to the following embodiments.

［第１実施形態］
図１〜図３に、本発明の第１実施形態に係る排気浄化装置の全体構造を示す。図１は縦断側面図（図２のＩ−Ｉ断面図）、図２は縦断後面図（図１のＩＩ−ＩＩ断面図）、図３は縦断前面図（図１のＩＩＩ−ＩＩＩ断面図）である。便宜上、直交三軸の各方向、すなわち前後左右上下の各方向を図示の如く定める。但しこれら各方向が図示の配置に関して説明の便宜上定められたものに過ぎない点に留意されたい。 First Embodiment
1 to 3 show the overall structure of an exhaust purification system according to a first embodiment of the present invention. 1 is a vertical cross-sectional side view (II cross-sectional view of FIG. 2), FIG. 2 is a vertical cross-sectional rear view (II-II cross-sectional view of FIG. 1), and FIG. 3 is a vertical cross-sectional front view (III-III cross-sectional view of FIG. 1) It is. For convenience, each direction of orthogonal three axes, that is, each direction of front, rear, left, right, upper and lower is defined as shown. However, it should be noted that these directions are merely defined for the convenience of description with respect to the illustrated arrangement.

排気浄化装置が適用される内燃機関（図示せず、エンジンともいう）は、車両に搭載されるディーゼルエンジンである。車両（図示せず）はトラック等の大型車両である。但し車両および内燃機関の種類、用途等に限定はなく、例えば車両は乗用車等の小型車両であってもよいし、エンジンはガソリンエンジンであってもよい。   An internal combustion engine (not shown, also referred to as an engine) to which an exhaust gas purification device is applied is a diesel engine mounted on a vehicle. The vehicle (not shown) is a large vehicle such as a truck. However, the type and application of the vehicle and the internal combustion engine are not limited. For example, the vehicle may be a small vehicle such as a passenger car, and the engine may be a gasoline engine.

図示するように、排気浄化装置１は、後述する複数の部材（触媒等）をコンパクトに纏めてキャニング（canning）状態で収容する密閉箱型のケーシング２を備える。本実施形態のケーシング２は直方体形状とされる。ケーシング２の後端壁２Ｒには、ケーシング２内にエンジンの排気ガスＧを導入するための装置入口管３と、ケーシング２内から排気ガスＧを排出するための装置出口管４とが取り付けられている。但し装置入口管３と装置出口管４の設置位置は任意に設定できる。   As illustrated, the exhaust gas purification device 1 includes a closed box type casing 2 that compactly holds a plurality of members (such as a catalyst) to be described later in a canning state. The casing 2 of the present embodiment has a rectangular parallelepiped shape. A device inlet pipe 3 for introducing exhaust gas G of the engine into the casing 2 and a device outlet pipe 4 for discharging exhaust gas G from the interior of the casing 2 are attached to the rear end wall 2R of the casing 2 ing. However, the installation positions of the apparatus inlet pipe 3 and the apparatus outlet pipe 4 can be set arbitrarily.

ケーシング２内では、金属製（本実施形態ではステンレス製）の複数の管および板が溶接等で取り付けられることにより、適宜空間が仕切られ、これにより排気ガスＧが流される排気通路５が画成されている。ここで「排気通路」とは、排気ガスＧが流される任意の空間をいい、その形状は任意である。管状であってもよいしチャンバ状であってもよい。排気通路５は排気ガスＧを前後方向に複数回折り返すように構成されている。   In the casing 2, a plurality of metal pipes (stainless steel in this embodiment) and plates are attached by welding or the like to appropriately divide the space, thereby defining the exhaust passage 5 through which the exhaust gas G flows. It is done. Here, the “exhaust passage” refers to any space through which the exhaust gas G flows, and its shape is arbitrary. It may be tubular or chamber-like. The exhaust passage 5 is configured to return the exhaust gas G back and forth a plurality of times.

ケーシング２内には、ケーシング２内を前後に仕切る前側隔壁板６と後側隔壁板７とが設けられている。前側隔壁板６とケーシング２の前端壁２Ｆとの間に前端チャンバ８Ｆが画成されている。後側隔壁板７とケーシング２の後端壁２Ｒとの間に後端チャンバ８Ｒが画成されている。前側隔壁板６と後側隔壁板７の間に中間チャンバ８Ｍが画成されている。   Inside the casing 2 are provided a front partition plate 6 and a rear partition plate 7 which divide the inside of the casing 2 back and forth. A front end chamber 8F is defined between the front partition plate 6 and the front end wall 2F of the casing 2. A rear end chamber 8R is defined between the rear partition wall 7 and the rear end wall 2R of the casing 2. An intermediate chamber 8M is defined between the front partition plate 6 and the rear partition plate 7.

以下、ケーシング２内における排気ガスＧのメインの流れを概略説明する。このメインの流れは図１〜図３に矢示する通りである。   The main flow of the exhaust gas G in the casing 2 will be briefly described below. This main flow is as shown by arrows in FIGS.

装置入口管３内を前方に流れてきた排気ガスは、そのまま、ケーシング２内左下に配置され前後方向に延びる第１通路９内を直進し、このときに第１酸化触媒２１とフィルタ２２を順に通過する。その後排気ガスは、前端チャンバ８Ｆ内に配置された送り管１９Ｐ内の送り通路１９を通じて、ケーシング２内中心部に配置された混合通路としての第２通路１０内に入る。このときに排気ガスは前向きから後向きへ折り返される。そして排気ガスは、第２通路１０内を前方から後方に流れた後、後端チャンバ８Ｒ内に入り、ここで図２に示すように二方向に分岐して、ケーシング２内右下に配置された第３通路１１と、ケーシング２内左上に配置された第４通路１２とに入る。このときに排気ガスは後向きから前向きへ折り返される。   The exhaust gas having flowed forward in the apparatus inlet pipe 3 goes straight in the first passage 9 disposed at the lower left in the casing 2 and extending in the front-rear direction as it is. At this time, the first oxidation catalyst 21 and the filter 22 are sequentially pass. Thereafter, the exhaust gas passes through the feed passage 19 in the feed pipe 19P disposed in the front end chamber 8F, and enters the second passage 10 as a mixing passage disposed in the central portion inside the casing 2. At this time, the exhaust gas is folded back from the forward direction. Then, the exhaust gas flows from the front to the rear in the second passage 10 and then enters the rear end chamber 8R, where it is branched in two directions as shown in FIG. And the fourth passage 12 disposed at the upper left in the casing 2. At this time, the exhaust gas is turned from the rear to the front.

排気ガスは、第３および第４通路１１，１２内を後方から前方に流れ、このときにＮＯｘ触媒２３と第２酸化触媒２４を順に通過する。その後排気ガスは、前端チャンバ８Ｆ内に入り、図３に示すように、ケーシング２内右上に配置された第５通路１３へと集約される。このときに排気ガスは前向きから後向きへ折り返される。その後排気ガスは、第５通路１３内を前方から後方に流れ、そのまま装置出口管４へと直進して排出される。   The exhaust gas flows from the rear to the front in the third and fourth passages 11 and 12, and at this time, passes through the NOx catalyst 23 and the second oxidation catalyst 24 in this order. Thereafter, the exhaust gas enters the front end chamber 8F and is concentrated to the fifth passage 13 disposed at the upper right in the casing 2 as shown in FIG. At this time, the exhaust gas is folded back from the forward direction. Thereafter, the exhaust gas flows from the front to the rear in the fifth passage 13 and travels straight to the apparatus outlet pipe 4 and is discharged.

このように排気通路５は、第１通路９、第２通路１０、第３通路１１、第４通路１２、第５通路１３、送り通路１９、前端チャンバ８Ｆおよび後端チャンバ８Ｒを含む。   Thus, the exhaust passage 5 includes the first passage 9, the second passage 10, the third passage 11, the fourth passage 12, the fifth passage 13, the feed passage 19, the front end chamber 8F and the rear end chamber 8R.

第２通路１０の上流端の位置には、還元剤としての尿素水を噴射する噴射弁１４が設けられている。噴射弁１０は、第２通路１０と同軸に後向きに配置され、第２通路１０の軸方向後方に向かって尿素水を噴霧状に噴射する。   At the position of the upstream end of the second passage 10, an injection valve 14 for injecting urea water as a reducing agent is provided. The injection valve 10 is disposed rearwardly and coaxially with the second passage 10, and injects urea water in the form of a spray toward the axial direction rearward of the second passage 10.

噴射弁１４は、尿素水の供給対象物である選択還元型ＮＯｘ触媒２３の上流側に配置される。そして噴射弁１４の下流側かつＮＯｘ触媒２３の上流側に位置する第２通路１０は、噴射弁１０から噴射された尿素水を排気ガスと混合させる混合通路としての役割を果たす。   The injection valve 14 is disposed upstream of the selective reduction NOx catalyst 23, which is an object to be supplied with urea water. The second passage 10 located downstream of the injection valve 14 and upstream of the NOx catalyst 23 serves as a mixing passage for mixing urea water injected from the injection valve 10 with the exhaust gas.

排気通路５には４種類の後処理部材、すなわち第１酸化触媒２１、フィルタ２２、選択還元型ＮＯｘ触媒２３および第２酸化触媒２４が、上流側から順に直列に設けられている。   In the exhaust passage 5, four types of post-treatment members, that is, a first oxidation catalyst 21, a filter 22, a selective reduction type NOx catalyst 23, and a second oxidation catalyst 24 are provided in series sequentially from the upstream side.

第１酸化触媒２１は、排気ガス中の未燃成分（炭化水素ＨＣおよび一酸化炭素ＣＯ）を酸化して浄化すると共に、このときの反応熱で排気ガスを加熱昇温する。   The first oxidation catalyst 21 oxidizes and purifies the unburned components (hydrocarbon HC and carbon monoxide CO) in the exhaust gas, and heats and heats the exhaust gas with the reaction heat at this time.

フィルタ２２は、所謂ディーゼルパティキュレートフィルタ（DPF: Diesel Particulate Filter）または触媒付煤フィルタ（CSF: Caterized Soot Filter）と称されるもので、触媒を担持した連続再生式フィルタである。フィルタ２２は、ウォールフロー型とされ、排気中に含まれる粒子状物質（以下PM: Particulate Matterという）を捕集すると共に、捕集したＰＭを触媒反応により連続的に酸化して燃焼除去する。   The filter 22 is a so-called diesel particulate filter (DPF) or a catalyzed soot filter (CSF), and is a continuous regeneration filter supporting a catalyst. The filter 22 is of a wall flow type and collects particulate matter (hereinafter referred to as PM: Particulate Matter) contained in the exhaust, and continuously oxidizes and burns and removes the collected PM by catalytic reaction.

選択還元型ＮＯｘ触媒（SCR: Selective Catalytic Reduction）２３は、尿素水を加水分解して得られるアンモニアＮＨ3とＮＯｘを反応させ、排気中のＮＯｘを窒素Ｎ2に還元する。 The Selective Catalytic Reduction (SCR) 23 reacts ammonia NH 3 obtained by hydrolyzing urea water with NOx, and reduces NOx in the exhaust to nitrogen N 2 .

第２酸化触媒２４は、アンモニアスリップ酸化触媒とも称され、ＮＯｘ触媒２３から排出された（スリップした）余剰アンモニアを酸化除去する。   The second oxidation catalyst 24, also referred to as an ammonia slip oxidation catalyst, oxidizes and removes excess ammonia discharged (slipped) from the NOx catalyst 23.

本実施形態において、ＮＯｘ触媒２３および第２酸化触媒２４の組み合わせは、第３通路１１と第４通路１２に互いに並列して計二つ設けられる。また図１に示すように、各組み合わせにおいて、ＮＯｘ触媒２３は上流側担体２３Ａの全体と、下流側担体２３Ｂの上流側部分とに形成され、第２酸化触媒２４は下流側担体２３Ｂの下流側部分にゾーンコートにより形成されている。但し両触媒の担体を個別にしても構わない。   In the present embodiment, a total of two combinations of the NOx catalyst 23 and the second oxidation catalyst 24 are provided in parallel with each other in the third passage 11 and the fourth passage 12. Further, as shown in FIG. 1, in each combination, the NOx catalyst 23 is formed on the entire upstream carrier 23A and on the upstream portion of the downstream carrier 23B, and the second oxidation catalyst 24 is downstream of the downstream carrier 23B. The portion is formed by zone coating. However, the carriers of both catalysts may be separate.

第１〜第５通路９〜１３および送り通路１９は、第１〜第５通路管９Ｐ〜１３Ｐおよび送り通路管１９Ｐにより画成されている。本実施形態において、第１〜第４通路９〜１２は直線状かつ断面円形、送り通路１９は直線状かつ断面長円形とされている。また第５通路１３は例えば図２に示すように、ケーシング２の右上コーナー部に直線状に形成されている。各通路に対応する各管も同じ形状である。しかしながら各通路および各管の形状は適宜変更可能である。   The first to fifth passages 9 to 13 and the feed passage 19 are defined by the first to fifth passage pipes 9P to 13P and the feed passage pipe 19P. In the present embodiment, the first to fourth passages 9 to 12 are straight and circular in cross section, and the feed passage 19 is straight and oval in cross section. The fifth passage 13 is formed in a straight line at the upper right corner of the casing 2 as shown in FIG. Each tube corresponding to each passage is also the same shape. However, the shape of each passage and each pipe can be changed appropriately.

排気流れ方向に沿って、第１通路管９Ｐは後端壁２Ｒから前端壁２Ｆまで延び、第２通路管１０Ｐは前端壁２Ｆから後側隔壁板７まで延び、第３通路管１１Ｐおよび第４通路管１２Ｐは後側隔壁板７から前側隔壁板６まで延び、第５通路管１３Ｐは前側隔壁板６から後端壁２Ｒまで延びている。従って、前端チャンバ８Ｆ内は、第１通路９の部分と、第２通路１０の部分と、送り通路１９の部分と、それ以外の部分とに仕切られる。また後端チャンバ８Ｒ内は、第１通路９の部分と、第５通路１３の部分と、それ以外の部分とに仕切られる。   Along the exhaust flow direction, the first passage pipe 9P extends from the rear end wall 2R to the front end wall 2F, and the second passage pipe 10P extends from the front end wall 2F to the rear partition plate 7, and the third passage pipe 11P and the fourth The passage pipe 12P extends from the rear partition plate 7 to the front partition plate 6, and the fifth passage pipe 13P extends from the front partition plate 6 to the rear end wall 2R. Accordingly, the inside of the front end chamber 8F is divided into the portion of the first passage 9, the portion of the second passage 10, the portion of the feed passage 19, and the other portion. Further, the inside of the rear end chamber 8R is divided into a portion of the first passage 9, a portion of the fifth passage 13, and a portion other than that.

次に、図４を参照して、本実施形態の主な特徴である第２通路１０の内部の構成を説明する。   Next, with reference to FIG. 4, the internal configuration of the second passage 10, which is a main feature of the present embodiment, will be described.

前述したように、第２通路１０の上流端には後方に向かって尿素水Ｕを噴射する噴射弁１４が設けられている。そして前端チャンバ８Ｆ内に位置する第２通路１０の左下側面部には送り通路１９が接続され、ここから第２通路１０内に排気ガスＧが導入される。   As described above, at the upstream end of the second passage 10, the injection valve 14 that injects the urea water U rearward is provided. A feed passage 19 is connected to the lower left side of the second passage 10 located in the front end chamber 8F, and the exhaust gas G is introduced into the second passage 10 from here.

尿素水噴霧と排気ガスＧは第２通路１０内を後方下流側に進むにつれて次第に混合されていく。本実施形態ではこうした混合を促進するため、折り返し通路３０が第２通路１０の内部に設けられている。折り返し通路３０は、図中矢示するように、排気ガスＧの流れを順流方向から逆流方向に折り返し、その後順流方向に折り返すように構成されている。本実施形態において、順流方向とは前方から後方に向かう流れの向きをいい、逆流方向とは後方から前方に向かう流れの向きをいう。   The urea water spray and the exhaust gas G are gradually mixed in the second passage 10 as they proceed rearward and downstream. In the present embodiment, the folded passage 30 is provided inside the second passage 10 in order to promote such mixing. The return passage 30 is configured to return the flow of the exhaust gas G from the forward flow direction to the reverse flow direction and then return to the forward flow direction, as indicated by arrows in the figure. In the present embodiment, the forward flow direction refers to the direction of flow going from the front to the rear, and the reverse flow direction refers to the direction of flow going from the rear to the front.

具体的には折り返し通路３０は、閉鎖部材３１とカバー部材３２により画成されている。これらは第２通路１０の中心軸Ｃと同軸に配置される。   Specifically, the return passage 30 is defined by the closing member 31 and the cover member 32. These are arranged coaxially with the central axis C of the second passage 10.

閉鎖部材３１は、第２通路１０内の周縁部を閉じると共に、上流側（前側）に向かって突出する連通管３３をその中心部に有する。連通管３３は、閉鎖部材３１の上流側と下流側を連通させるためのものである。本実施形態において連通管３３は閉鎖部材３１に一体に形成されているが、別体で形成して溶接等により固着しても構わない。閉鎖部材３１は全体として、板状かつリング状の部材とされ、下流側（後側）に向かって凸となる湾曲断面形状、具体的には半円形の断面形状を有する。これにより閉鎖部材３１は、１回目の折り返しを行う排気ガスＧのアウトコーナー側をスムーズに案内することができる。   The closing member 31 closes the peripheral edge in the second passage 10 and has a communication pipe 33 projecting toward the upstream side (front side) at its center. The communication pipe 33 is for communicating the upstream side and the downstream side of the closing member 31. In the present embodiment, the communication pipe 33 is integrally formed with the closing member 31. However, the communication pipe 33 may be separately formed and fixed by welding or the like. The closing member 31 is a plate-like and ring-shaped member as a whole, and has a curved cross-sectional shape that is convex toward the downstream side (rear side), specifically, a semicircular cross-sectional shape. Thereby, the closing member 31 can guide the outside corner side of the exhaust gas G which performs the first folding smoothly.

カバー部材３２は、連通管３３を上流側から隙間を隔てて覆う。カバー部材３２は、先端側が上流側に向けられた先細り形状の部分を有する。ここで「先細り形状」とは、基端側から先端側に向かって延びると共に、先端側に向かうにつれ徐々に縮径する形状をいう。先細り形状には、錐体、錘台、半球状、ドーム状等の各形状が含まれる。錐体形状には、円錐、四角錐、多角錘等の各形状が含まれる。錘台形状には、円錐台、四角錐台、多角錘台等の各形状が含まれる。先細り形状については、これら各形状から任意の形状を採用できるが、本実施形態では加工の容易性等を考慮して円錐形状を採用している。   The cover member 32 covers the communication pipe 33 with a gap from the upstream side. The cover member 32 has a tapered portion whose distal end is directed upstream. Here, the “tapered shape” refers to a shape that extends from the proximal side toward the distal side and gradually reduces in diameter toward the distal side. The tapered shape includes shapes such as cones, frustums, hemispheres, and domes. The pyramidal shape includes shapes such as a cone, a square pyramid, and a polygonal pyramid. The frustum shape includes various shapes such as a truncated cone, a square frustum, and a polygonal frustum. With regard to the tapered shape, an arbitrary shape can be adopted from these respective shapes, but in the present embodiment, a conical shape is adopted in consideration of ease of processing and the like.

カバー部材３２は、短い直管状の下流端部（後端部）３２Ａを除いたほぼ全体部分が円錐形状とされている。カバー部材３２は板材により形成されている。カバー部材３２の最大外径は、第２通路管１０Ｐの内径より小さく、連通管３３の外径より大きくされる。なお本実施形態ではカバー部材３２の最大外径が下流端部３２Ａにより規定される。下流端部３２Ａは、連通管３３の外周部を半径方向外側から隙間を隔てて覆う。また連通管３３の前方にもカバー部材３２との間に隙間が形成される。カバー部材３２の裏側には、中心部が連通管３３内に向かって突出された湾曲凸板３４が溶接等により一体的に固着されている。カバー部材３２は図示しない複数の支柱により第２通路１０内に同軸状態で保持される。   The cover member 32 has a conical shape substantially in its entirety except for the short straight tubular downstream end (rear end) 32A. The cover member 32 is formed of a plate material. The maximum outer diameter of the cover member 32 is smaller than the inner diameter of the second passage pipe 10P and larger than the outer diameter of the communication pipe 33. In the present embodiment, the maximum outer diameter of the cover member 32 is defined by the downstream end 32A. The downstream end 32A covers the outer peripheral portion of the communication pipe 33 with a gap from the radially outer side. In addition, a gap is formed between the cover member 32 and the front of the communication pipe 33. On the back side of the cover member 32, a curved convex plate 34 whose central portion protrudes toward the inside of the communication pipe 33 is integrally fixed by welding or the like. The cover member 32 is coaxially held in the second passage 10 by a plurality of support posts (not shown).

本実施形態において、折り返し通路３０は第２通路１０の出口部に設けられている。そして連通管３３は後端チャンバ８Ｒ内に開口している。   In the present embodiment, the return passage 30 is provided at the outlet of the second passage 10. The communication pipe 33 opens into the rear end chamber 8R.

図示するように、折り返し通路３０において排気ガスＧが１回目の折り返しをなすとき、排気ガスＧのアウトコーナー側は閉鎖部材３１により案内され、排気ガスＧのインコーナー側はカバー部材３２の下流端部３２Ａにより案内される。そして排気ガスＧが２回目の折り返しをなすとき、排気ガスＧのアウトコーナー側はカバー部材３２および湾曲凸板３４により案内され、排気ガスＧのインコーナー側は連通管３３の入口端により案内される。   As illustrated, when the exhaust gas G makes a first turn in the turning passage 30, the out corner side of the exhaust gas G is guided by the closing member 31, and the in corner side of the exhaust gas G is the downstream end of the cover member 32. It is guided by the part 32A. When the exhaust gas G makes a second turn, the outside corner side of the exhaust gas G is guided by the cover member 32 and the curved convex plate 34, and the in-corner side of the exhaust gas G is guided by the inlet end of the communication pipe 33. Ru.

こうして排気ガスＧは、折り返し通路３０を通過するとき２回折り返され、第２通路１０内の最外周部から内周側に向かって１回折り返された後、さらに内周側に向かってもう１回折り返され、その後後端チャンバ８Ｒ内に直進する。   Thus, the exhaust gas G is reciprocated twice when passing through the turnback passage 30, and re-reflected one turn from the outermost peripheral portion in the second passage 10 toward the inner peripheral side, and then further to the inner peripheral side. It is folded back and then travels straight into the rear end chamber 8R.

本実施形態では、こうした折り返し通路３０を第２通路１０の内部に設けたので、第２通路１０の限られた前後長範囲内で、実質的な通路長を拡大し、尿素水噴霧と排気ガスＧの混合通路長を拡大できる。よって、噴射された尿素水と排気ガスの混合を確実に促進することが可能である。またこれにより、排気ガスによる尿素水の加熱を促進し、尿素水の加水分解を促進し、アンモニア生成効率を高め、ＮＯｘ触媒を高効率で作動させることが可能となる。そして排気浄化性能を高めることができる。   In the present embodiment, since the folded passage 30 is provided inside the second passage 10, the passage length is substantially expanded within the limited length range of the second passage 10, and the urea water spray and the exhaust gas are formed. The mixing passage length of G can be extended. Therefore, it is possible to reliably promote the mixing of the injected urea water and the exhaust gas. This also promotes the heating of the aqueous urea solution by the exhaust gas, promotes the hydrolysis of the aqueous urea solution, increases the ammonia generation efficiency, and enables the NOx catalyst to operate with high efficiency. And exhaust purification performance can be improved.

また、排気ガスＧが１回目の折り返しをなすとき、排気ガスＧのアウトコーナー側が湾曲された閉鎖部材３１により案内されるので、折り返しをスムーズになすことができる。同様に、排気ガスＧが２回目の折り返しをなすとき、排気ガスＧのアウトコーナー側が、円錐形のカバー部材３２の裏側（後側）と、湾曲状の湾曲凸板３４とにより案内されるので、折り返しをスムーズになすことができる。よって排気ガスＧが折り返し通路３０を通過するときの圧力損失を最小限に止めることができる。   In addition, when the exhaust gas G is folded back for the first time, the outside corner side of the exhaust gas G is guided by the curved closing member 31, so that the folding can be smoothly performed. Similarly, when the exhaust gas G makes a second turn, the outside corner side of the exhaust gas G is guided by the back side (rear side) of the conical cover member 32 and the curved convex plate 34. , Can be folded smoothly. Therefore, the pressure loss when the exhaust gas G passes through the turnaround passage 30 can be minimized.

加えて、カバー部材３２が先細り形状（本実施形態では円錐形状）とされているので、後方に向かう排気ガスＧをスムーズに外周側に案内することができる。そしてカバー部材３２は、高温の排気ガス中に常時曝されているので、排気ガスの熱を蓄熱する蓄熱体としても機能する。この蓄熱した高温のカバー部材３２に尿素水（または尿素水と排気ガスの混合気）が当たったときに尿素水を加熱し、その加水分解を促進することができる。   In addition, since the cover member 32 has a tapered shape (conical shape in the present embodiment), the exhaust gas G directed rearward can be smoothly guided to the outer peripheral side. And since the cover member 32 is always exposed to high temperature exhaust gas, it functions also as a thermal storage body which stores the heat of exhaust gas. When the heat stored in the high temperature cover member 32 hits the urea water (or a mixture of urea water and exhaust gas), the urea water can be heated to promote its hydrolysis.

本実施形態では、円錐形カバー部材３２の裏側の空間を利用して折り返し通路３０を形成するので、空間の利用効率を高めることができる。   In the present embodiment, the space behind the conical cover member 32 is used to form the turnaround passage 30, so that the utilization efficiency of the space can be enhanced.

また折り返し通路３０を第２通路１０の出口部に設け、カバー部材３２を噴射弁１４から最大限離間させたので、尿素水をカバー部材３２の手前でできるだけ蒸発させてからカバー部材３２に到達させることができる。よって、カバー部材３２に尿素水の液滴が付着してカバー部材３２の温度が低下し、その蓄熱効果が失われることを可能な限り抑制できる。   Further, since the return passage 30 is provided at the outlet of the second passage 10 and the cover member 32 is separated as much as possible from the injection valve 14, the urea water is evaporated as much as possible in front of the cover member 32 before reaching the cover member 32. be able to. Therefore, the droplet of the urea water adheres to the cover member 32, the temperature of the cover member 32 decreases, and the heat storage effect can be suppressed as much as possible.

本実施形態の排気浄化装置１は、密閉箱型のケーシング２内に複数回折り返す排気通路５を形成し、その排気通路５内に複数の後処理部材（触媒等）を配置したので、マフラー（消音器）としても機能する。よって別途マフラーを設けずに済み、製造コストを低減できる。   In the exhaust gas purification apparatus 1 of the present embodiment, the exhaust passage 5 is formed in the closed box type casing 2 so as to be folded back, and a plurality of post-processing members (such as catalysts) are disposed in the exhaust passage 5. It also functions as a silencer). Therefore, it is not necessary to separately provide a muffler, and the manufacturing cost can be reduced.

なお、本実施形態の折り返し通路３０はあくまで排気通路５の内部に形成されたものであって、排気通路５自体を折り返すことにより形成されたものではない。従って、第２通路１０から後端チャンバ８Ｒを経て第３および第４通路１１，１２に入るときの折り返しは、本実施形態の折り返し通路３０とは無関係である。   The return passage 30 of the present embodiment is formed only inside the exhaust passage 5 and is not formed by turning back the exhaust passage 5 itself. Therefore, the return from the second passage 10 through the rear end chamber 8R to the third and fourth passages 11 and 12 is irrelevant to the return passage 30 of this embodiment.

本実施形態は次のような変形例も可能である。例えば必要に応じて折り返し通路３０を複数設けることも可能である。上記の閉鎖部材３１は連通管３３を含め、全体として湾曲断面形状であったが、角張った断面形状としてもよい。湾曲凸板３４は省略してもよい。但し湾曲凸板３４があると、カバー部材３２の円錐先端裏側まで排気ガスが浸入するのを防止し、より早いタイミングでスムーズに排気ガスを折り返すことができるので、好ましい。連通管３３は、中心部に一つのみだけでなく、複数設けられてもよい。   The following modification is also possible in this embodiment. For example, it is also possible to provide a plurality of return passages 30 as needed. The above-mentioned closing member 31 has a curved cross-sectional shape as a whole including the communication pipe 33, but may have an angular cross-sectional shape. The curved convex plate 34 may be omitted. However, the presence of the curved convex plate 34 is preferable because it can prevent the exhaust gas from invading to the back side of the conical tip end of the cover member 32, and the exhaust gas can be smoothly folded back at an earlier timing. Not only one communicating pipe 33 may be provided at the central portion, but a plurality of communicating pipes 33 may be provided.

［第２実施形態］
次に、本発明の第２実施形態を説明する。なお第１実施形態と同様の部分には図中同一符号を付して説明を割愛し、以下、第１実施形態との相違点を主に説明する。 Second Embodiment
Next, a second embodiment of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted. Hereinafter, differences from the first embodiment will be mainly described.

図５に示すように、本実施形態は第２通路１０付近の構成が第１実施形態と主に相違する。すなわち、第２通路１０は、その中心軸Ｃを基準として、半径方向内側に位置する内側第２通路４１と、半径方向外側に位置する外側第２通路４２とを含む。外側第２通路４２は、内側第２通路４１の半径方向外側に隣接して位置され、内側第２通路４１を囲繞し、内側第２通路４１の出口部から排出された排気ガスを、内側第２通路４１内の流れ方向とは逆方向に流す。折り返し通路３０は内側第２通路４１内に配置される。   As shown in FIG. 5, the configuration in the vicinity of the second passage 10 in the present embodiment is mainly different from that in the first embodiment. That is, the second passage 10 includes an inner second passage 41 positioned radially inward with respect to the central axis C, and an outer second passage 42 positioned radially outward. The outer second passage 42 is positioned adjacent to the radially outer side of the inner second passage 41 and surrounds the inner second passage 41, and exhaust gas discharged from the outlet of the inner second passage 41 can be 2 flow in the direction opposite to the flow direction in the passage 41. The return passage 30 is disposed in the inner second passage 41.

内側第２通路４１と外側第２通路４２は中心軸Ｃと同軸に配置される。内側第２通路４１と外側第２通路４２はそれぞれ内側第２通路管４１Ｐと外側第２通路管４２Ｐにより画成される。よってこれら内側および外側第２通路管４１Ｐ，４２Ｐは同軸の二重管である。外側第２通路管４２Ｐの下流端（後端）は、前述の湾曲凸板３４に類似の湾曲凸板４３により閉止される。湾曲凸板４３は湾曲凸板３４と前後対称的に配置される。   The inner second passage 41 and the outer second passage 42 are disposed coaxially with the central axis C. The inner second passage 41 and the outer second passage 42 are respectively defined by an inner second passage pipe 41P and an outer second passage pipe 42P. Thus, the inner and outer second passage pipes 41P and 42P are coaxial double pipes. The downstream end (rear end) of the outer second passage pipe 42P is closed by a curved convex plate 43 similar to the aforementioned curved convex plate 34. The curved convex plate 43 is disposed symmetrically with the curved convex plate 34 in the front-rear direction.

折り返し通路３０は、内側第２通路４１の出口部付近に配置され、第１実施形態より若干上流側に配置されている。   The folded passage 30 is disposed in the vicinity of the outlet of the second inner passage 41, and is disposed slightly upstream of the first embodiment.

この構成によれば、送り通路１９から内側第２通路４１に導入された排気ガスＧは、内側第２通路４１内を後方に向かって流れ、折り返し通路３０を通過し、内側第２通路４１から排出される。その後、湾曲凸板４３に当たって折り返され、外側第２通路４２内に入り、外側第２通路４２内を前方に向かって流れ、前端チャンバ８Ｆに排出される。排気ガスＧが内側第２通路４１から外側第２通路４２に折り返されるとき、排気ガスＧのアウトコーナー側が湾曲凸板４３により案内されるので、折り返しをスムーズになすことができる。   According to this configuration, the exhaust gas G introduced into the inner second passage 41 from the feed passage 19 flows rearward in the inner second passage 41, passes through the turnaround passage 30, and from the inner second passage 41. Exhausted. Thereafter, the curved convex plate 43 is folded back, enters the outer second passage 42, flows forward in the outer second passage 42, and is discharged to the front end chamber 8F. When the exhaust gas G is folded back from the inner second passage 41 to the outer second passage 42, the out-corner side of the exhaust gas G is guided by the curved convex plate 43, so that the folding can be smoothly performed.

本実施形態では、内側第２通路４１の半径方向外側に外側第２通路４２を二重管状に設けたので、第２通路１０の限られた前後長範囲内で、実質的な通路長をさらに拡大し、尿素水と排気ガスＧの混合通路長をさらに拡大できる。よって尿素水と排気ガスの混合をさらに促進することが可能である。   In the present embodiment, since the outer second passage 42 is provided in a double tubular shape on the radially outer side of the inner second passage 41, a substantial passage length is further added within the limited front and back length range of the second passage 10. It can be expanded, and the mixing passage length of urea water and exhaust gas G can be further expanded. Therefore, it is possible to further promote the mixing of the urea water and the exhaust gas.

また、外側第２通路４２を流れる排気ガスにより、内側第２通路４１内の排気ガスおよび尿素水を保温もしくは加熱することができるので、尿素水の加水分解をさらに促進することができる。   In addition, since the exhaust gas and the urea water in the inner second passage 41 can be kept warm or heated by the exhaust gas flowing through the outer second passage 42, the hydrolysis of the urea water can be further promoted.

その余の作用効果は第１実施形態と同様である。   The remaining effects and advantages are the same as in the first embodiment.

ちなみに、本実施形態では第２通路１０から排出される排気ガスＧの向きが第１実施形態と逆となり、排気ガスＧが前端チャンバ８Ｆ内に排出される。従ってケーシング２内の構成が図６に示すように若干変更されている。   Incidentally, in the present embodiment, the direction of the exhaust gas G discharged from the second passage 10 is opposite to that in the first embodiment, and the exhaust gas G is discharged into the front end chamber 8F. Therefore, the configuration in the casing 2 is slightly changed as shown in FIG.

すなわち、第３および第４通路１１，１２内におけるＮＯｘ触媒２３と第２酸化触媒２４の配置が前後逆とされる。第５通路１３は省略され、その第５通路１３のあった前側隔壁板６と後側隔壁板７の位置は閉じられている。   That is, the arrangement of the NOx catalyst 23 and the second oxidation catalyst 24 in the third and fourth passages 11 and 12 is reversed. The fifth passage 13 is omitted, and the positions of the front partition plate 6 and the rear partition plate 7 where the fifth passage 13 was located are closed.

外側第２通路４２から前端チャンバ８Ｆ内に排出された排気ガスＧは、二方向に分岐して、第３通路１１と第４通路１２に入る。このときに排気ガスは前向きから後向きへ折り返される。そして排気ガスは、第３および第４通路１１，１２内を前方から後方に流れ、このときにＮＯｘ触媒２３と第２酸化触媒２４を順に通過する。その後排気ガスは、後端チャンバ８Ｒ内に入り、後端チャンバ８Ｒ内で装置出口管４へと集約され、排出される。   The exhaust gas G discharged from the outer second passage 42 into the front end chamber 8F bifurcates in two directions and enters the third passage 11 and the fourth passage 12. At this time, the exhaust gas is folded back from the forward direction. Then, the exhaust gas flows from the front to the rear in the third and fourth passages 11 and 12 and at this time passes through the NOx catalyst 23 and the second oxidation catalyst 24 in order. Thereafter, the exhaust gas enters the rear end chamber 8R, is concentrated to the device outlet pipe 4 in the rear end chamber 8R, and is exhausted.

本実施形態においては、内側第２通路４１および外側第２通路４２がそれぞれ特許請求の範囲にいう内側排気通路および外側排気通路に相当する。   In the present embodiment, the inner second passage 41 and the outer second passage 42 correspond to the inner exhaust passage and the outer exhaust passage in the claims respectively.

変形例に関し、外側第２通路管４２Ｐの下流端（後端）は単なる平板により閉止されていてもよい。   Regarding the modification, the downstream end (rear end) of the outer second passage pipe 42P may be closed by a simple flat plate.

［第３実施形態］
次に、本発明の第３実施形態を説明する。 Third Embodiment
Next, a third embodiment of the present invention will be described.

図７に示すように、本実施形態も、第２通路１０付近の構成が第１実施形態と相違する。なお全体構成は図１に示したものと同様である。   As shown in FIG. 7, also in the present embodiment, the configuration in the vicinity of the second passage 10 is different from that of the first embodiment. The entire configuration is the same as that shown in FIG.

第２通路１０および第２通路管１０Ｐは、第１実施形態のものよりも前後長が短くされ、それら後端部の位置が後側隔壁板７よりも前方に位置されている。そしてその代わりに、連通管３３が後方に延長され、後側隔壁板７の位置まで延びている。   The second passage 10 and the second passage pipe 10P have front and rear lengths shorter than those of the first embodiment, and the positions of their rear end portions are positioned forward of the rear partition plate 7. And instead, the communicating pipe 33 is extended rearward and extends to the position of the rear partition plate 7.

閉鎖部材３１は、第２通路管１０Ｐの後端部を半径方向内側に向かって断面半円状に折曲することにより、第２通路管１０Ｐに一体に形成されている。カバー部材３２の直管状下流端部３２Ａが、複数の支柱５１を介して第２通路管１０Ｐに連結される。本実施形態では湾曲凸板３４が省略されている。   The closing member 31 is integrally formed with the second passage pipe 10P by bending the rear end portion of the second passage pipe 10P radially inward in a semicircular shape in cross section. The straight tubular downstream end 32A of the cover member 32 is connected to the second passage pipe 10P via a plurality of columns 51. The curved convex plate 34 is omitted in the present embodiment.

連通管３３は、閉鎖部材３１と別体で形成され、閉鎖部材３１の中心開口部３１Ａに溶接等で固着される。連通管３３の入口部３３Ｂが中心開口部３１Ａに対し上流側（前側）に突出される。中心開口部３１Ａより下流側（後側）の位置では、連通管３３にテーパ状拡径部３３Ａが形成され、排気ガスＧの排出をスムーズに行えるようになっている。   The communication tube 33 is formed separately from the closing member 31 and fixed to the central opening 31A of the closing member 31 by welding or the like. The inlet 33B of the communication pipe 33 is projected upstream (front side) with respect to the central opening 31A. At a position on the downstream side (rear side) of the central opening 31A, a tapered enlarged diameter portion 33A is formed in the communication pipe 33, and exhaust gas G can be smoothly discharged.

本実施形態では、カバー部材３２とは別の蓄熱体、すなわち蓄熱部材５２が追加して設けられている。蓄熱部材５２は、噴射弁１４の下流側かつ折り返し通路３０の上流側の位置に設けられている。特に蓄熱部材５２は、第２通路１０内におけるカバー部材３２よりも上流側の位置に設けられ、カバー部材３２よりも噴射弁１４に近い位置に設けられている。   In the present embodiment, a heat storage body different from the cover member 32, that is, a heat storage member 52 is additionally provided. The heat storage member 52 is provided on the downstream side of the injection valve 14 and on the upstream side of the turnaround passage 30. In particular, the heat storage member 52 is provided at a position upstream of the cover member 32 in the second passage 10 and is provided at a position closer to the injection valve 14 than the cover member 32.

蓄熱部材５２は、カバー部材３２と同様、先端側が上流側に向けられた先細り形状の部分を有する。ここでは先細り形状として、加工の容易性等を考慮して円錐台形状を採用している。   Similar to the cover member 32, the heat storage member 52 has a tapered portion whose tip end is directed upstream. Here, as the tapered shape, a truncated cone shape is adopted in consideration of ease of processing and the like.

蓄熱部材５２は、第２通路１０の全断面に亘って設けられ、そのほぼ全体部分である円錐台形状の先細り部５５を有すると共に、その先細り部５５に複数の開口部５３を有する。   The heat storage member 52 is provided over the entire cross section of the second passage 10 and has a truncated cone-shaped tapered portion 55 which is a substantially entire portion thereof, and has a plurality of openings 53 in the tapered portion 55.

より詳細には、蓄熱部材５２は板材により形成され、先細り部５５は中心軸Ｃに同軸の円錐台形状とされる。その円錐台の底部をなす基端部５４が、中心軸Ｃに垂直なリング状とされ、第２通路管１０Ｐの内周面に溶接等で固着される。基端部５４から上流側に向かって先細りとなる先細り部５５には、図８にも示すように、前後に長い略三角状もしくは台形状の開口部５３が、全周に亘って複数形成される。これにより開口部５３の間にはフィン５６が形成される。本実施形態においてフィン５６は先細り部５５の周方向に沿っている。   More specifically, the heat storage member 52 is formed of a plate material, and the tapered portion 55 has a frusto-conical shape coaxial with the central axis C. A base end 54 forming a bottom of the truncated cone is formed in a ring shape perpendicular to the central axis C, and is fixed to the inner peripheral surface of the second passage pipe 10P by welding or the like. As shown in FIG. 8, a plurality of substantially triangular or trapezoidal openings 53 long in the front-rear direction are formed on the entire circumference of the tapered portion 55 which is tapered from the proximal end 54 toward the upstream side. Ru. Fins 56 are thus formed between the openings 53. In the present embodiment, the fins 56 extend in the circumferential direction of the tapered portion 55.

円錐台の頂部をなす蓄熱部材５２の先端部５７には、中心軸Ｃに垂直な先端板５８が固設されている。先端板５８は、先端部５７を塞ぐ役割と、排気ガスの流れを前面で受けて蓄熱する役割と、噴射弁１４から噴射された尿素水を当てて尿素水の加熱を促進する役割とを有する。   A tip plate 58 perpendicular to the central axis C is fixed to the tip portion 57 of the heat storage member 52 which forms the top of the truncated cone. The tip plate 58 has a role of closing the tip portion 57, a role of receiving the flow of exhaust gas at the front and storing heat, and a role of applying urea water injected from the injection valve 14 to promote heating of the urea water. .

他方、連通管３３の入口部３３Ｂは、その周方向に分割された複数の分割片３３Ｃを有する。図９および図１０にも示すように、これら複数の分割片３３Ｃは、周方向に向かうにつれ、半径方向内側および外側へと交互に折曲されている。   On the other hand, the inlet 33B of the communicating pipe 33 has a plurality of divided pieces 33C divided in the circumferential direction. As also shown in FIGS. 9 and 10, the plurality of divided pieces 33C are alternately bent radially inward and outward in the circumferential direction.

より具体的には、連通管３３の入口部３３Ｂの前端から所定距離後方までの間に、周方向等間隔で複数のスリットが設けられ、このスリットの位置を境に入口部３３Ｂが半径方向内側および外側へと交互に折曲される。これにより、交互に向きの異なる複数の分割片３３Ｃが形成される。   More specifically, a plurality of slits are provided at equal intervals in the circumferential direction between the front end of the inlet 33B of the communication tube 33 and a predetermined distance rearward, and the inlet 33B is radially inward of the position of the slits. And alternately bent outward. Thereby, a plurality of divided pieces 33C whose directions are different alternately are formed.

この構成によれば、送り通路１９から内側第２通路４１に導入された排気ガスＧは、内側第２通路４１内を後方に向かって流れた後、蓄熱部材５２に当たって複数の開口部５３を通過し、蓄熱部材５２の内側に入る。そしてカバー部材３２に案内されつつ、折り返し通路３０に至り、折り返し通路３０を通過した後、連通管３３を通じて後端チャンバ８Ｒに排出される。   According to this configuration, the exhaust gas G introduced from the feed passage 19 to the inner second passage 41 flows rearward in the inner second passage 41 and then strikes the heat storage member 52 and passes through the plurality of openings 53 Into the inside of the heat storage member 52. Then, while being guided by the cover member 32, it reaches the turnback passage 30, passes through the turnback passage 30, and is then discharged to the rear end chamber 8 R through the communication pipe 33.

排気ガスが蓄熱部材５２を通過する際、排気ガスの熱が蓄熱部材５２に伝達され、蓄熱部材５２が蓄熱される。この蓄熱部材５２に、排気ガス中の尿素水が当たることにより、尿素水が加熱され、その加水分解が促進される。その後も同様に尿素水がカバー部材３２に当たるので、これにより尿素水の加熱および加水分解がさらに促進される。   When the exhaust gas passes through the heat storage member 52, the heat of the exhaust gas is transmitted to the heat storage member 52, and the heat storage member 52 is stored. When the urea water in the exhaust gas strikes the heat storage member 52, the urea water is heated and its hydrolysis is promoted. Since the urea water also hits the cover member 32 thereafter, the heating and hydrolysis of the urea water are further promoted.

排気ガスが蓄熱部材５２を通過する際、排気ガスの流れが幾分乱れるので、排気ガスと尿素水の混合を促進できる。   When the exhaust gas passes through the heat storage member 52, the flow of the exhaust gas is somewhat disturbed, so that the mixing of the exhaust gas and the urea water can be promoted.

他方、排気ガスが連通管３３の入口部３３Ｂに入るとき、排気ガスは図９に矢示するように、分割片３３Ｃの間の隙間３３Ｄからも入ってくる。連通管３３の軸方向に素直に入ってくる流れと、これとは別方向から隙間３３Ｄを通って入ってくる流れとが衝突するため、入口部３３Ｂの内部に流れの乱れが生じ、これにより排気ガスと尿素水の混合を促進できる。   On the other hand, when the exhaust gas enters the inlet portion 33B of the communication pipe 33, the exhaust gas also enters from the gap 33D between the divided pieces 33C as shown by the arrow in FIG. Since the flow coming in straight in the axial direction of the communication pipe 33 and the flow coming in through the gap 33D from another direction collide with each other, turbulence in the flow occurs in the inside of the inlet portion 33B, and thereby It can promote the mixing of exhaust gas and urea water.

その余の作用効果は第１実施形態と同様である。   The remaining effects and advantages are the same as in the first embodiment.

このように、本実施形態では蓄熱部材５２を設けたので、尿素水および排気ガスの混合と尿素水の加熱とを促進し、尿素水の加水分解を促進することができる。また、連通管３３の入口部３３Ｂに複数の分割片３３Ｃを設けたので、尿素水および排気ガスの混合を促進し、尿素水の加水分解を促進できる。   As described above, since the heat storage member 52 is provided in the present embodiment, the mixing of the urea water and the exhaust gas and the heating of the urea water can be promoted, and the hydrolysis of the urea water can be promoted. Further, since the plurality of divided pieces 33C are provided at the inlet 33B of the communicating pipe 33, the mixing of the urea water and the exhaust gas can be promoted, and the hydrolysis of the urea water can be promoted.

蓄熱部材５２を先細り形状（本実施形態では円錐台形状）にしたので、蓄熱部材５２を設けたことによる排気抵抗の増加を可能な限り抑制できる。また分割片３３Ｃは、連通管３３の管端部を切り込んで折り曲げ加工するだけなので、加工が容易である。   Since the heat storage member 52 is tapered (in the embodiment, a truncated cone shape), the increase in the exhaust resistance due to the provision of the heat storage member 52 can be suppressed as much as possible. Further, since the divided piece 33C is merely cut and bent at the end of the communication pipe 33, it is easy to process.

本実施形態の変形例に関し、例えば蓄熱部材５２の開口部５３の形状を変えてもよく、例えば円形や四角形等とすることができる。また連通管３３に関しては、例えば複数の分割片３３Ｃを別体で設けて溶接等で固着することが考えられる。本実施形態と第２実施形態を組み合わせ、本実施形態の第２通路１０を二重管構造にしてもよい。   Regarding the modification of the present embodiment, for example, the shape of the opening 53 of the heat storage member 52 may be changed, and it may be, for example, circular or square. Moreover, regarding the communicating pipe 33, for example, it is conceivable to separately provide a plurality of divided pieces 33C and fix them by welding or the like. The present embodiment and the second embodiment may be combined to make the second passage 10 of the present embodiment a double pipe structure.

以上、本発明の実施形態を詳細に述べたが、本発明の実施形態は他にも様々考えられる。   Although the embodiments of the present invention have been described in detail, various other embodiments of the present invention are conceivable.

（１）本発明に係る折り返し通路は、上述のような密閉箱型ケーシングを有する排気浄化装置のみならず、通常の排気浄化装置にも適用可能である。   (1) The folded passage according to the present invention can be applied not only to the exhaust gas purification device having the above-described closed box type casing but also to a general exhaust gas purification device.

（２）触媒は、必ずしもＮＯｘ触媒でなくてもよく、選択還元型ＮＯｘ触媒でなくてもよい。また触媒に供給する還元剤も、触媒の種類に応じて変更可能である。   (2) The catalyst may not necessarily be the NOx catalyst, and may not be the selective reduction type NOx catalyst. The reducing agent supplied to the catalyst can also be changed according to the type of catalyst.

前述の各実施形態の構成は、特に矛盾が無い限り、部分的にまたは全体的に組み合わせることが可能である。本発明の実施形態は前述の実施形態のみに限らず、特許請求の範囲によって規定される本発明の思想に包含されるあらゆる変形例や応用例、均等物が本発明に含まれる。従って本発明は、限定的に解釈されるべきではなく、本発明の思想の範囲内に帰属する他の任意の技術にも適用することが可能である。   The configurations of the embodiments described above can be partially or totally combined unless there is a particular contradiction. The embodiments of the present invention are not limited to the above-described embodiments, and all variations, applications, and equivalents included in the concept of the present invention defined by the claims are included in the present invention. Accordingly, the present invention should not be interpreted in a limited manner, and can be applied to any other technology falling within the scope of the present invention.

１ 排気浄化装置
５ 排気通路
１０ 第２通路
１４ 噴射弁
２３ ＮＯｘ触媒
３０ 折り返し通路
３１ 閉鎖部材
３２ カバー部材
３３ 連通管
３３Ｂ 入口部
３３Ｃ 分割片
４１ 内側第２通路
４２ 外側第２通路
５２ 蓄熱部材
５３ 開口部 DESCRIPTION OF SYMBOLS 1 exhaust gas purification device 5 exhaust passage 10 second passage 14 injection valve 23 NOx catalyst 30 folded passage 31 closing member 32 cover member 33 communication pipe 33B inlet part 33C divided pieces 41 inner second passage 42 outer second passage 52 heat storage member 53 opening Department

Claims (8)

内燃機関の排気ガスが流される排気通路と、
前記排気通路に配置された触媒と、
前記触媒の上流側に設けられ、前記排気通路内に還元剤を噴射する噴射弁と、
前記噴射弁の下流側かつ前記触媒の上流側の位置における前記排気通路の内部に設けられ、排気ガスの流れを順流方向から逆流方向に折り返し、その後順流方向に折り返すように構成された折り返し通路と、
を備えたことを特徴とする内燃機関の排気浄化装置。 An exhaust passage through which exhaust gas of an internal combustion engine flows;
A catalyst disposed in the exhaust passage;
An injection valve provided on the upstream side of the catalyst and injecting a reducing agent into the exhaust passage;
A return passage provided inside the exhaust passage at a position downstream of the injection valve and upstream of the catalyst, configured to turn the flow of the exhaust gas from the forward flow direction to the reverse flow direction, and thereafter to turn back in the forward flow direction; ,
An exhaust gas purification device for an internal combustion engine, comprising: 前記折り返し通路が、
前記排気通路内の周縁部を閉じると共に、上流側に向かって突出する連通管を有する閉鎖部材と、
前記連通管の入口部を上流側から隙間を隔てて覆うカバー部材と、
により画成される
請求項１に記載の内燃機関の排気浄化装置。 The said return passage is
And a closing member having a communicating pipe projecting toward the upstream side while closing the peripheral portion in the exhaust passage.
A cover member that covers the inlet portion of the communication pipe with a gap from the upstream side;
The exhaust gas purification device for an internal combustion engine according to claim 1 defined by: 前記カバー部材が、先端側が上流側に向けられた先細り形状の部分を有する
請求項２に記載の内燃機関の排気浄化装置。 The exhaust gas purification apparatus for an internal combustion engine according to claim 2, wherein the cover member has a tapered portion whose front end side is directed upstream. 前記先細り形状が円錐形状である
請求項３に記載の内燃機関の排気浄化装置。 The exhaust gas purification device for an internal combustion engine according to claim 3, wherein the tapered shape is a conical shape. 前記連通管の前記入口部が、その周方向に分割された複数の分割片を有し、前記複数の分割片は、半径方向内側および外側へと交互に折曲されている
請求項２〜４のいずれか一項に記載の内燃機関の排気浄化装置。 The inlet portion of the communication tube has a plurality of divided pieces divided in the circumferential direction, and the plurality of divided pieces are alternately bent radially inward and outward. An exhaust purification system of an internal combustion engine according to any one of the above. 前記排気通路が、半径方向内側に位置された内側排気通路と、前記内側排気通路の半径方向外側に隣接して位置され、前記内側排気通路を囲繞し、前記内側排気通路から排出された排気ガスを逆方向に流す外側排気通路とを含み、
前記折り返し通路が、前記内側排気通路内に配置される
請求項１〜５のいずれか一項に記載の内燃機関の排気浄化装置。 The exhaust passage is located radially inward of an inner exhaust passage and radially adjacent to the inner exhaust passage, and surrounds the inner exhaust passage, and exhaust gas discharged from the inner exhaust passage And an outer exhaust passage to flow in the opposite direction,
The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 5, wherein the return passage is disposed in the inner exhaust passage. 前記噴射弁の下流側かつ前記折り返し通路の上流側の位置に設けられ、排気ガスの熱を蓄熱する蓄熱部材をさらに備える
請求項１〜６のいずれか一項に記載の内燃機関の排気浄化装置。 The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 6, further comprising a heat storage member provided at a position downstream of the injection valve and upstream of the return passage and storing heat of exhaust gas. . 前記蓄熱部材は、先端側が上流側に向けられた先細り形状の部分を有し、当該部分に複数の開口部を有する。
請求項７に記載の内燃機関の排気浄化装置。 The heat storage member has a tapered portion whose tip end is directed upstream, and has a plurality of openings in the portion.
An exhaust purification system of an internal combustion engine according to claim 7.
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