WO2017150513A1 - Exhaust gas purification device for internal combustion engine - Google Patents

Exhaust gas purification device for internal combustion engine Download PDF

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Publication number
WO2017150513A1
WO2017150513A1 PCT/JP2017/007727 JP2017007727W WO2017150513A1 WO 2017150513 A1 WO2017150513 A1 WO 2017150513A1 JP 2017007727 W JP2017007727 W JP 2017007727W WO 2017150513 A1 WO2017150513 A1 WO 2017150513A1
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Prior art keywords
exhaust gas
casing
pipe
inlet
outlet
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PCT/JP2017/007727
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French (fr)
Japanese (ja)
Inventor
幸博 川島
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いすゞ自動車株式会社
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Priority to CN201780014359.6A priority Critical patent/CN108884740A/en
Publication of WO2017150513A1 publication Critical patent/WO2017150513A1/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
    • 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
    • F01N3/18—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 methods of operation; Control
    • F01N3/20—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 methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • 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

Definitions

  • the present disclosure relates to an exhaust gas purification device for an internal combustion engine including an aftertreatment unit.
  • an exhaust gas purification device including an aftertreatment unit provided in the middle of an exhaust pipe and having a plurality of catalysts for purifying harmful substances in exhaust gas is known.
  • the post-treatment unit is accommodated in a casing in order to keep the temperature of the catalyst at a high temperature.
  • the casing is provided with an inlet hole through which the exhaust gas inlet pipe of the aftertreatment unit is inserted and an outlet hole through which the exhaust gas outlet pipe of the aftertreatment unit is inserted.
  • an object of the present disclosure is an internal combustion engine that can suppress the heat of the post-processing unit from being taken away by the casing and suppress the temperature decrease of the catalyst of the post-processing unit.
  • An object is to provide an exhaust gas purification device.
  • An exhaust gas purification apparatus for an internal combustion engine includes an exhaust pipe, an aftertreatment unit provided in the middle of the exhaust pipe and having a plurality of catalysts for purifying exhaust gas, and a casing that houses the aftertreatment unit.
  • an outlet side heat insulating seal member provided in a gap between the exhaust gas outlet pipe and the outlet hole.
  • the exhaust gas purification apparatus for an internal combustion engine it is possible to suppress the heat of the aftertreatment unit from being taken away by the casing, and to exhibit an excellent effect that the temperature decrease of the catalyst of the aftertreatment unit can be suppressed.
  • FIG. 1 is a schematic configuration diagram illustrating an exhaust gas purification apparatus according to an embodiment of the present disclosure.
  • FIG. 2 is an enlarged view of a main part of FIG.
  • FIG. 1 is a schematic configuration diagram illustrating an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present disclosure
  • FIG. 2 is an enlarged view of a main part thereof.
  • an exhaust gas purification apparatus 100 is an aftertreatment unit having an exhaust pipe 2 through which exhaust gas from an internal combustion engine 1 passes and a plurality of catalysts 10 provided in the middle of the exhaust pipe 2 for purifying exhaust gas. 3 and a casing 4 that houses the post-processing unit 3.
  • the internal combustion engine 1 is a multi-cylinder compression ignition 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.
  • the exhaust pipe 2 is a pipe that is connected to the exhaust manifold 12 and discharges the exhaust gas from the exhaust manifold 12 in the downstream direction (direction indicated by the arrow G) and releases it to the atmosphere.
  • the exhaust pipe 2 includes an upstream exhaust pipe 21 positioned upstream of the post-processing unit 3 and a downstream exhaust pipe 22 positioned downstream of the post-processing unit 3.
  • the upstream exhaust pipe 21 has a flange 21a at its downstream end
  • the downstream exhaust pipe 22 has a flange 22a at its upstream end.
  • the front-rear and left-right directions of the post-processing unit 3 are shown in FIG. Note that the front-rear and left-right directions of the illustrated post-processing unit 3 are irrelevant to the front-rear and left-right directions of the vehicle, and are merely determined for convenience of explanation.
  • the internal combustion engine 1 is placed vertically on the vehicle, and the left direction of the post-processing unit 3 coincides with the front direction of the vehicle.
  • 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 provided, a second catalyst casing 34 in which at least one catalyst 10 is provided, A connecting pipe 35 connecting the first catalyst casing 33 and the second catalyst casing 34 and an addition valve 36 for adding urea water are provided. Further, the post-processing unit 3 has a substantially symmetrical structure.
  • the exhaust gas inlet pipe 31 is arranged at the front end and the left side of the post-processing unit 3 and extends from the front to the rear, and the front end is connected to the downstream end of the upstream exhaust pipe 21. Further, the exhaust gas outlet pipe 32 is disposed at the front end and the right side of the post-processing unit 3, extends from the front to the rear, and the front end is connected to the upstream end of the downstream exhaust pipe 22.
  • 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 the flange 31a.
  • 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 the flange 32a.
  • the flanges connected to each other are detachably fixed by fastening means such as bolts (not shown).
  • 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 enlarged-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.
  • the first catalyst casing 33 has an oxidation catalyst (DOC: Diesel Oxidation Catalyst) 10a and a particulate filter (hereinafter referred to as “the catalyst”) from the upstream side through the first heat insulating buffer member (mat) 37 at the position of the first enlarged diameter portion 33c. (Referred to as “DPF”) 10b.
  • DOC Diesel Oxidation Catalyst
  • the catalyst a particulate filter
  • 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 with heat generated during 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.
  • the DPF 10b collects and removes particulate matter (PM) contained in the exhaust gas.
  • a so-called wall flow type DPF 10b is used in which openings at both ends of a honeycomb-shaped heat-resistant substrate are alternately closed in a checkered pattern.
  • any type of filter that physically captures PM can be used, such as a mesh-shaped foam shape.
  • the DPF 10b is a so-called continuous regeneration type DPF with a catalyst in which a noble metal (catalyst) such as Pt is supported on the inner wall thereof.
  • a noble metal such as Pt
  • HC in the exhaust gas supplied to the DPF 10b is oxidized and burned by the catalytic action, and at this time, PM accumulated in the DPF 10b is simultaneously burned and removed.
  • DPF10b since DPF10b has a catalyst, DPF10b shall also be included in the catalyst 10 said to this indication here.
  • 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. Further, the second catalyst casing 34 is formed with a second diameter-expanded portion 34c having a diameter larger than that of the connecting pipe 35 positioned on the upstream side and the exhaust gas outlet pipe 32 positioned on the downstream side.
  • the NOx catalyst 10c and the ammonia oxidation catalyst 10d are installed from the upstream side through the second heat insulating buffer member (mat) 38 at the position of the second enlarged diameter portion 34c.
  • the NOx catalyst 10c is a catalyst for purifying nitrogen oxides 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 from urea water.
  • SCR selective reduction type NOx catalyst
  • the ammonia oxidation catalyst 10d is a catalyst that generates N 2 by oxidizing excess ammonia (NH 3 ) that has not been consumed in the reduction of NOx by the NOx catalyst 10c.
  • the first catalyst casing 33 and the second catalyst casing 34 are arranged on the left and right in parallel with each other. Further, the first side hole 33b and the second side hole 34d are disposed at positions facing each other.
  • the connecting pipe 35 is disposed at a position between the first catalyst casing 33 and the second catalyst casing 34 in the left-right direction, and connects the first side hole 33b and the second side hole 34b.
  • the connecting pipe 35 extends from the first side hole 33b toward the second side hole 34b (the right side in the figure) and bends forward, and the second side hole 34b extends to the first side hole 33b.
  • a second portion 35b extending toward the side (the left side in the figure) and bent forward.
  • the first portion 35a indicates a portion from X1 to X2 in the drawing
  • the second portion 35b indicates a portion from Y1 to Y2 in the drawing.
  • the connecting pipe 35 has a third portion 35c that extends forward from the downstream end X2 of the first portion 35a, is folded back in a U-shape and extends rearward, and is connected to the upstream end Y2 of the second portion 35b. . That is, the connection pipe 35 is formed in such a manner that it is folded in a U-shape, so that the pipe length of the connection pipe 35 becomes longer than linearly connecting the first side hole 33b and the second side hole 34d.
  • the addition valve 36 is arranged so as to add urea water from the rear to the front from the bent part L of the first part 35a toward the folded part U of the third part 35c.
  • the casing 4 is made of a box-type casing using a heat-resistant material such as stainless steel, and covers the entire post-processing unit 3 in a substantially airtight manner.
  • a heat insulating material 5 such as glass wool is laid on almost the entire inner peripheral surface of the casing 4 to keep the post-processing unit 3 warm.
  • an attachment portion 42 for attaching the addition valve 36 is formed at a portion located behind the bent portion L of the post-processing unit 3.
  • the attachment portion 42 is formed to be recessed forward, and an outer insertion hole 43 extending in the front-rear direction is formed at the front end thereof.
  • an inner insertion hole 35 d is formed coaxially with the outer insertion hole 43 on the rear end surface of the bent portion L of the post-processing unit 3.
  • the addition valve 36 is inserted into both the outer insertion hole 43 and the inner insertion hole 35 d from the outside (rear) of the casing 4, and is fixed to the casing 4 by a boss portion 44 provided in the attachment portion 42.
  • An inlet hole 46 through which the exhaust gas inlet pipe 31 is inserted with a gap S1 is formed in the front surface 45 of the casing 4 so that the exhaust gas inlet pipe 31 of the post-processing unit 3 protrudes to the outside (front) of the casing 4.
  • an outlet hole 47 through which the exhaust gas outlet pipe 32 is inserted with a gap S2 is formed in the front surface 45 of the casing 4 so that the exhaust gas outlet pipe 32 of the post-processing unit 3 protrudes to the outside (front) of the casing 4.
  • the inlet side heat insulating seal member 6 is provided in the gap S1 between the exhaust gas inlet pipe 31 and the inlet hole 46
  • the outlet side heat insulating seal member 7 is provided in the gap S2 between the exhaust gas outlet pipe 32 and the outlet hole 47.
  • the inlet side heat insulating seal member 6 is made of a ring-shaped seal member through which the exhaust gas inlet pipe 31 can be inserted, and is made of a material having a low heat transfer coefficient, for example, heat resistant rubber.
  • a support member 48 for attaching the inlet side heat insulating seal member 6 to the casing 4 is formed so as to protrude from the back surface of the front surface 45 of the casing 4 and around the inlet hole 46.
  • a support member 49 similar to the support member 48 is formed on the back surface of the front surface 45 of the casing 4 and around the outlet hole 47.
  • the support member 48 is formed in a ring shape, and has an inner diameter that is larger than the inlet hole 46 and slightly smaller than the outer diameter of the inlet-side heat insulating seal member 6.
  • the inlet side heat insulating seal member 6 is press-fitted into the support member 48 from behind.
  • the exhaust gas of the internal combustion engine 1 passes through the upstream exhaust pipe 21 from the exhaust manifold 12 and flows into the first catalyst casing 33 through the exhaust gas inlet pipe 31.
  • the exhaust gas flowing into the first catalyst casing 33 passes through the oxidation catalyst 10a, whereby unburned components (hydrocarbon HC and carbon monoxide CO) in the exhaust gas are oxidized and purified.
  • the exhaust gas that has passed through the oxidation catalyst 10a flows into the DPF 10b, and particulate matter (PM) contained in the exhaust gas is collected and removed by the DPF 10b.
  • PM particulate matter
  • 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 90 ° along the bent shape of the first portion 35a. The direction is changed to flow to the third portion 35c.
  • the exhaust gas that has flowed to the third portion 35c turns 180 ° backward at the turn-up portion U, flows to the second portion 35b behind, and turns 90 ° along the bent shape of the second portion 35b. It flows into the second catalyst casing 34 through the side hole 34b.
  • the addition valve 36 disposed 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 added urea water is turned 180 ° rearward at the folded portion U, flows to the second rear portion 35b, is turned 90 ° along the bent shape of the second portion 35b, and the second side hole 34b.
  • the second catalyst casing 34 Through the second catalyst casing 34.
  • the exhaust gas containing at least one of urea water and ammonia passes through the NOx catalyst 10c.
  • the NOx catalyst 10c reduces NOx with ammonia generated by hydrolysis of urea water.
  • the surplus ammonia that has not been consumed in the reduction of NOx by the NOx catalyst 10c comes into contact with the ammonia oxidation catalyst 10d and is oxidized, and release to the atmosphere is suppressed.
  • the exhaust gas that has passed through the ammonia oxidation catalyst 10d is discharged to the downstream exhaust pipe 22 through the exhaust gas outlet pipe 32 and is released from the downstream exhaust pipe 22 to the atmosphere.
  • 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 active temperature range. To do. Therefore, it is effective to keep the temperature of each catalyst 10 as high as possible.
  • the post-processing unit 3 is accommodated in the casing 4 in which the heat insulating material 5 is laid on the inner peripheral surface, thereby suppressing the post-processing unit 3 from being cooled by outside air or traveling wind,
  • the temperature of the catalyst 10 can be kept high.
  • the inlet-side heat insulating seal member 6 is provided in the gap S1 between the exhaust gas inlet pipe 31 and the inlet hole 46 and the exhaust gas outlet pipe 32 is provided.
  • the outlet side heat insulating seal member 7 is provided in the gap S2 between the outlet hole 47 and the outlet hole 47.
  • the inlet side heat insulating seal member 6 and the outlet side heat insulating seal member 7 seal the gaps S1 and S2 between the exhaust gas outlet pipe 32 and the outlet hole 47, respectively, thereby corroding the post-processing unit 3 due to water intrusion from the gap. Can be prevented.
  • the connecting pipe 35 is formed in a U-shape, it is connected rather than connecting the first side hole 33b and the second side hole 34d linearly.
  • the length of the tube 35 can be increased, and the post-processing unit 3 can be made compact, which is advantageous for in-vehicle use.
  • the urea water added from the addition valve 36 passes through this long and folded connection pipe 35.
  • the urea water can be sufficiently stirred and mixed with the exhaust gas, and the hydrolysis of the urea water is further promoted.
  • ammonia is efficiently generated, which is advantageous for improving the NOx purification rate in the NOx catalyst 10c.
  • the exhaust gas purifying apparatus for an internal combustion engine according to the present disclosure is useful in that the heat of the aftertreatment unit is suppressed from being taken away by the casing, and the temperature decrease of the catalyst of the aftertreatment unit can be suppressed.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Silencers (AREA)

Abstract

This exhaust gas purification device 100 for an internal combustion engine 1 is provided with: an exhaust pipe 2; a post-treatment unit 3 which is provided with a plurality of catalysts 10 for purifying exhaust gas; a casing 4 in which the post-treatment unit 3 is accommodated; an inlet hole 46 which is provided in the casing 4, and through which an exhaust gas inlet pipe 31 of the post-treatment unit 3 is passed such that a gap S1 is provided therebetween; an outlet hole 47 through which an exhaust gas outlet pipe 32 of the post-treatment unit 3 is passed such that a gap S2 is provided therebetween; a heat-insulating material 5 provided on the inner peripheral surface of the casing 4; and heat-insulating seal members 6, 7 which are provided in the gaps S1, S2.

Description

内燃機関の排ガス浄化装置Exhaust gas purification device for internal combustion engine
　本開示は、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 disclosure relates to an exhaust gas purification device for an internal combustion engine including an aftertreatment 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 purification device including an aftertreatment unit provided in the middle of an exhaust pipe and having a plurality of catalysts for purifying harmful substances in exhaust gas is known. .
日本国特開２００８－２４０５２５号公報Japanese Unexamined Patent Publication No. 2008-240525
　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。このケーシングには、後処理ユニットの排ガス入口管が挿通される入口孔と、後処理ユニットの排ガス出口管が挿通される出口孔とが設けられる。 In the above exhaust gas purifying apparatus, it is conceivable that the post-treatment unit is accommodated in a casing in order to keep the temperature of the catalyst at a high temperature. The casing is provided with an inlet hole through which the exhaust gas inlet pipe of the aftertreatment unit is inserted and an outlet hole through which the exhaust gas outlet pipe of the aftertreatment unit is inserted.
　しかしながら、これらの挿通部分にて入口管（または出口管）と入口孔（または出口孔）が接触していると、例えば、暖機時には、この接触部分から後処理ユニットの熱がケーシングに奪われてしまい、触媒の温度が低下してしまう。 However, if the inlet pipe (or outlet pipe) and the inlet hole (or outlet hole) are in contact with each other at these insertion portions, for example, at the time of warming up, the heat of the aftertreatment unit is taken away from the contact portion by the casing. As a result, the temperature of the catalyst decreases.
　そこで、本開示は、かかる事情に鑑みて創案され、その目的は、後処理ユニットの熱がケーシングに奪われることを抑制し、後処理ユニットの触媒の温度低下を抑制することができる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 disclosure has been devised in view of such circumstances, and an object of the present disclosure is an internal combustion engine that can suppress the heat of the post-processing unit from being taken away by the casing and suppress the temperature decrease of the catalyst of the post-processing unit. An object is to provide an exhaust gas purification device.
　本開示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、前記ケーシングに設けられ、前記後処理ユニットの排ガス入口管を外部に突出させるように前記排ガス入口管が隙間をもって挿通される入口孔と、前記ケーシングに設けられ、前記後処理ユニットの排ガス出口管を外部に突出させるように前記排ガス出口管が隙間をもって挿通される出口孔と、前記ケーシングの内周面上に設けられた断熱材と、前記排ガス入口管と前記入口孔との隙間に設けられた入口側断熱シール部材と、前記排ガス出口管と前記出口孔との隙間に設けられた出口側断熱シール部材と、を備えたことを特徴とする。 An exhaust gas purification apparatus for an internal combustion engine according to the present disclosure includes an exhaust pipe, an aftertreatment unit provided in the middle of the exhaust pipe and having a plurality of catalysts for purifying exhaust gas, and a casing that houses the aftertreatment unit. An inlet hole provided in the casing and through which the exhaust gas inlet pipe is inserted with a gap so as to project the exhaust gas inlet pipe of the aftertreatment unit to the outside, and an exhaust gas outlet pipe of the aftertreatment unit provided in the casing. An exhaust hole through which the exhaust gas outlet pipe is inserted with a gap, a heat insulating material provided on the inner peripheral surface of the casing, and a gap between the exhaust gas inlet pipe and the inlet hole. And an outlet side heat insulating seal member provided in a gap between the exhaust gas outlet pipe and the outlet hole.
　本開示に係る内燃機関の排ガス浄化装置では、後処理ユニットの熱がケーシングに奪われることを抑制し、後処理ユニットの触媒の温度低下を抑制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 purification apparatus for an internal combustion engine according to the present disclosure, it is possible to suppress the heat of the aftertreatment unit from being taken away by the casing, and to exhibit an excellent effect that the temperature decrease of the catalyst of the aftertreatment unit can be suppressed.
図１は、本開示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。FIG. 1 is a schematic configuration diagram illustrating an exhaust gas purification apparatus according to an embodiment of the present disclosure. 図２は、図１の要部拡大図である。FIG. 2 is an enlarged view of a main part of FIG.
　以下、添付図面に基づいて、本開示の一実施形態を説明する。図１は、本開示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り、図２は、その要部拡大図である。 Hereinafter, an embodiment of the present disclosure will be described based on the accompanying drawings. FIG. 1 is a schematic configuration diagram illustrating an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present disclosure, and FIG. 2 is an enlarged view of a main part thereof.
　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 purification apparatus 100 is an aftertreatment unit having an exhaust pipe 2 through which exhaust gas from an internal combustion engine 1 passes and a plurality of catalysts 10 provided in the middle of the exhaust pipe 2 for purifying exhaust gas. 3 and a casing 4 that houses the post-processing 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 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 discharges the exhaust gas from the exhaust manifold 12 in the downstream direction (direction indicated by the arrow G) and releases it 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 positioned upstream of the post-processing unit 3 and a downstream exhaust pipe 22 positioned downstream of the post-processing 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-rear and left-right directions of the post-processing unit 3 are shown in FIG. Note that the front-rear and left-right directions of the illustrated post-processing unit 3 are irrelevant to the front-rear and left-right directions of the vehicle, and are merely determined for convenience of explanation. In the present embodiment, the internal combustion engine 1 is placed vertically on the vehicle, and the left direction of the post-processing unit 3 coincides with 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、少なくとも一つの触媒１０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 provided, a second catalyst casing 34 in which at least one catalyst 10 is provided, A connecting pipe 35 connecting the first catalyst casing 33 and the second catalyst casing 34 and an addition valve 36 for adding urea water are provided. Further, 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 and the left side of the post-processing unit 3 and extends from the front to the rear, and the front end is connected to the downstream end of the upstream exhaust pipe 21. Further, the exhaust gas outlet pipe 32 is disposed at the front end and the right side of the post-processing unit 3, extends from the front to the rear, and the front end is connected to the upstream end of the downstream 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 the 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 the 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 enlarged-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。 The first catalyst casing 33 has an oxidation catalyst (DOC: Diesel Oxidation Catalyst) 10a and a particulate filter (hereinafter referred to as “the catalyst”) from the upstream side through the first heat insulating buffer member (mat) 37 at the position of the first enlarged diameter portion 33c. (Referred to as “DPF”) 10b.
　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 with heat generated during 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) contained in the exhaust gas. In the present embodiment, a so-called wall flow type DPF 10b is used 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 captures PM can be used, such as a mesh-shaped 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も本開示にいう触媒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 in which a noble metal (catalyst) such as Pt is supported on the inner wall thereof. In this case, during normal operation of the engine, HC in the exhaust gas supplied to the DPF 10b is oxidized and burned by the catalytic action, and at this time, PM accumulated in the DPF 10b is simultaneously burned and removed. In addition, since DPF10b has a catalyst, DPF10b shall also be included in the catalyst 10 said to this indication 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、上流側に位置する連結管３５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. Further, the second catalyst casing 34 is formed with a second diameter-expanded portion 34c having a diameter larger than that of the connecting pipe 35 positioned on the upstream side and the exhaust gas outlet pipe 32 positioned 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 installed from the upstream side through the second heat insulating buffer member (mat) 38 at the position of the second enlarged 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 oxides 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 from 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 generates N 2 by oxidizing excess ammonia (NH 3 ) that has not been consumed in the reduction of NOx by the NOx catalyst 10c.
　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 on the left and right in parallel with each other. Further, the first side hole 33b and the second side hole 34d are disposed 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側孔３３ｂと第２側孔３４ｂとを連結する。 The connecting pipe 35 is disposed at a position between the first catalyst casing 33 and the second catalyst casing 34 in the left-right direction, and connects the first side hole 33b and the second side hole 34b.
　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Ｘ１からＸ２までの部分を示し、第２部分３５ｂは、図中のＹ１からＹ２までの部分を示す。 More specifically, the connecting pipe 35 extends from the first side hole 33b toward the second side hole 34b (the right side in the figure) and bends forward, and the second side hole 34b extends to the first side hole 33b. A second portion 35b extending toward the side (the left side in the figure) and bent forward. Specifically, the first portion 35a indicates a portion from X1 to X2 in the drawing, and the second portion 35b indicates a portion from Y1 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、Ｕ字状に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。 The connecting pipe 35 has a third portion 35c that extends forward from the downstream end X2 of the first portion 35a, is folded back in a U-shape and extends rearward, and is connected to the upstream end Y2 of the second portion 35b. . That is, the connection pipe 35 is formed in such a manner that it is folded in a U-shape, so that the pipe length of the connection pipe 35 becomes longer than linearly connecting the first side hole 33b and the second side hole 34d.
　添加弁３６は、第１部分３５ａの折れ曲がり部分Ｌから第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ように配置される。 The addition valve 36 is arranged so as to add urea water from the rear to the front from the bent part L of the first part 35a toward the folded part U of the third part 35c.
　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５が敷設される。 The casing 4 is made of a box-type casing using a heat-resistant material such as stainless steel, and covers the entire post-processing unit 3 in a substantially airtight manner. A heat insulating material 5 such as glass wool is laid on almost the entire inner peripheral surface of the casing 4 to keep the post-processing unit 3 warm.
　ケーシング４の後面４１には、後処理ユニット３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４２が形成される。取付部４２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４３が形成される。また、後処理ユニット３の折れ曲がり部分Ｌの後端面には、外側挿通孔４３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４３と内側挿通孔３５ｄの両方に挿通され、取付部４２に設けられたボス部４４によって、ケーシング４に固定される。 On the rear surface 41 of the casing 4, an attachment portion 42 for attaching the addition valve 36 is formed at a portion located behind the bent portion L of the post-processing unit 3. The attachment portion 42 is formed to be recessed forward, and an outer insertion hole 43 extending in the front-rear direction is formed at the front end thereof. In addition, an inner insertion hole 35 d is formed coaxially with the outer insertion hole 43 on the rear end surface of the bent portion L of the post-processing unit 3. The addition valve 36 is inserted into both the outer insertion hole 43 and the inner insertion hole 35 d from the outside (rear) of the casing 4, and is fixed to the casing 4 by a boss portion 44 provided in the attachment portion 42.
　ケーシング４の前面４５には、後処理ユニット３の排ガス入口管３１をケーシング４の外部（前方）に突出させるように、排ガス入口管３１が隙間Ｓ１をもって挿通される入口孔４６が形成される。また、ケーシング４の前面４５には、後処理ユニット３の排ガス出口管３２をケーシング４の外部（前方）に突出させるように、排ガス出口管３２が隙間Ｓ２をもって挿通される出口孔４７が形成される。 An inlet hole 46 through which the exhaust gas inlet pipe 31 is inserted with a gap S1 is formed in the front surface 45 of the casing 4 so that the exhaust gas inlet pipe 31 of the post-processing unit 3 protrudes to the outside (front) of the casing 4. Further, an outlet hole 47 through which the exhaust gas outlet pipe 32 is inserted with a gap S2 is formed in the front surface 45 of the casing 4 so that the exhaust gas outlet pipe 32 of the post-processing unit 3 protrudes to the outside (front) of the casing 4. The
　本実施形態においては、排ガス入口管３１と入口孔４６との隙間Ｓ１に、入口側断熱シール部材６が設けられ、排ガス出口管３２と出口孔４７との隙間Ｓ２に、出口側断熱シール部材７が設けられる。これらの構造は、入口孔４６側と出口孔４７側で、ほぼ同様に構成される。よって、これらの詳細な構造については、入口孔４６側のみを説明し、出口孔４７側の説明を省略する。 In the present embodiment, the inlet side heat insulating seal member 6 is provided in the gap S1 between the exhaust gas inlet pipe 31 and the inlet hole 46, and the outlet side heat insulating seal member 7 is provided in the gap S2 between the exhaust gas outlet pipe 32 and the outlet hole 47. Is provided. These structures are configured in substantially the same manner on the inlet hole 46 side and the outlet hole 47 side. Therefore, for these detailed structures, only the inlet hole 46 side will be described, and description of the outlet hole 47 side will be omitted.
　図２にも詳細に示すように、入口側断熱シール部材６は、排ガス入口管３１が挿通可能なリング状のシール部材からなり、熱伝達率の低い材料、例えば耐熱性ゴムで形成される。 As shown in detail in FIG. 2, the inlet side heat insulating seal member 6 is made of a ring-shaped seal member through which the exhaust gas inlet pipe 31 can be inserted, and is made of a material having a low heat transfer coefficient, for example, heat resistant rubber.
　ケーシング４の前面４５の裏面で且つ入口孔４６の周囲には、入口側断熱シール部材６をケーシング４に取り付けるための支持部材４８が突出して形成される。なお、ケーシング４の前面４５の裏面で且つ出口孔４７の周囲には、支持部材４８と同様の支持部材４９が形成されている。 A support member 48 for attaching the inlet side heat insulating seal member 6 to the casing 4 is formed so as to protrude from the back surface of the front surface 45 of the casing 4 and around the inlet hole 46. A support member 49 similar to the support member 48 is formed on the back surface of the front surface 45 of the casing 4 and around the outlet hole 47.
　より詳しくは、支持部材４８は、リング状に形成され、入口孔４６より大きく、且つ、入口側断熱シール部材６の外径より僅かに小さい内径を有する。入口側断熱シール部材６は、支持部材４８に後方から圧入される。 More specifically, the support member 48 is formed in a ring shape, and has an inner diameter that is larger than the inlet hole 46 and slightly smaller than the outer diameter of the inlet-side heat insulating seal member 6. The inlet side heat insulating seal member 6 is press-fitted into the support member 48 from behind.
　この状態において、組み立て時に、排ガス入口管３１が入口孔４６に後方から前方に向けて挿入されると、排ガス入口管３１の外周面が入口側断熱シール部材６の内周面に密着した状態で固定される（圧入される）。この結果、入口側断熱シール部材６によって、排ガス入口管３１と入口孔４６との隙間Ｓ１がシールされると共に、入口管３１からケーシング４への熱伝達が大幅に抑制される。 In this state, when the exhaust gas inlet pipe 31 is inserted into the inlet hole 46 from the rear to the front during assembly, the outer peripheral surface of the exhaust gas inlet pipe 31 is in close contact with the inner peripheral surface of the inlet-side heat insulating seal member 6. Fixed (press-fit). As a result, the clearance S1 between the exhaust gas inlet pipe 31 and the inlet hole 46 is sealed by the inlet-side heat insulating seal member 6, and heat transfer from the inlet pipe 31 to the casing 4 is greatly suppressed.
　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 function and effect of the exhaust gas purification 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 through the upstream exhaust pipe 21 from the exhaust manifold 12 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 (hydrocarbon 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 particulate matter (PM) contained in the exhaust gas is collected and removed by the DPF 10b.
　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 90 ° along the bent shape of the first portion 35a. The direction is changed to flow 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。 The exhaust gas that has flowed to the third portion 35c turns 180 ° backward at the turn-up portion U, flows to the second portion 35b behind, and turns 90 ° along the bent shape of the second portion 35b. It flows into the second catalyst casing 34 through the side 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。添加された尿素水は、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。 Here, the addition valve 36 disposed 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 added urea water is turned 180 ° rearward at the folded portion U, flows to the second rear portion 35b, is turned 90 ° along the bent shape of the second portion 35b, and the second side hole 34b. Through the second catalyst casing 34.
　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 with ammonia generated by hydrolysis of 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。 The surplus ammonia that has not been consumed in the reduction of NOx by the NOx catalyst 10c comes into contact with the ammonia oxidation catalyst 10d and is oxidized, and release to the atmosphere is suppressed.
　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 exhaust pipe 22 through the exhaust gas outlet pipe 32 and is released from the downstream exhaust pipe 22 to the atmosphere.
　以上の作用のうち、上記の酸化触媒１０ａ、ＤＰＦ１０ｂ、ＮＯｘ触媒１０ｃ、およびアンモニア酸化触媒１０ｄについては、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。 Of the above operations, 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 active temperature range. To do. 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５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-processing unit 3 is accommodated in the casing 4 in which the heat insulating material 5 is laid on the inner peripheral surface, thereby suppressing the post-processing unit 3 from being cooled by outside air or traveling wind, The temperature of the catalyst 10 can be kept high.
　一方、仮に、後処理ユニット３の排ガス入口管３１（または排ガス出口管３２）が、ケーシング４の前面４５に形成された入口孔４６（または出口孔４７）と、接触していると、この接触部分から後処理ユニット３の熱がケーシング４に奪われて、各触媒１０の温度が低下してしまう。これにより、例えば暖機時には、各触媒１０の活性化が遅れてしまう。 On the other hand, if the exhaust gas inlet pipe 31 (or the exhaust gas outlet pipe 32) of the post-processing unit 3 is in contact with the inlet hole 46 (or outlet hole 47) formed in the front surface 45 of the casing 4, this contact occurs. The heat of the aftertreatment unit 3 is taken away by the casing 4 from the portion, and the temperature of each catalyst 10 is lowered. Thereby, for example, at the time of warm-up, activation of each catalyst 10 is delayed.
　そこで、本実施形態の排ガス浄化装置１００においては、図１および図２に示す通り、排ガス入口管３１と入口孔４６との隙間Ｓ１に、入口側断熱シール部材６を設けると共に、排ガス出口管３２と出口孔４７との隙間Ｓ２に、出口側断熱シール部材７を設ける。 Therefore, in the exhaust gas purification apparatus 100 of the present embodiment, as shown in FIGS. 1 and 2, the inlet-side heat insulating seal member 6 is provided in the gap S1 between the exhaust gas inlet pipe 31 and the inlet hole 46 and the exhaust gas outlet pipe 32 is provided. The outlet side heat insulating seal member 7 is provided in the gap S2 between the outlet hole 47 and the outlet hole 47.
　これにより、後処理ユニット３の熱がケーシング４に奪われることを抑制し、後処理ユニット３の各触媒１０の温度低下を抑制することが可能になる。 Thereby, it is possible to suppress the heat of the post-processing unit 3 from being taken away by the casing 4 and to suppress the temperature drop of each catalyst 10 of the post-processing unit 3.
　また、入口側断熱シール部材６と出口側断熱シール部材７は、それぞれ排ガス出口管３２と出口孔４７との隙間Ｓ１，Ｓ２をシールすることで、隙間からの水侵入による後処理ユニット３の腐食を防止することができる。 In addition, the inlet side heat insulating seal member 6 and the outlet side heat insulating seal member 7 seal the gaps S1 and S2 between the exhaust gas outlet pipe 32 and the outlet hole 47, respectively, thereby corroding the post-processing unit 3 due to water intrusion from the gap. Can be prevented.
　また、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ため、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の管長を長くし、その一方で、後処理ユニット３をコンパクトに構成することが可能となるので、車載に有利である。 Further, in the post-processing unit 3 of the present embodiment, since the connecting pipe 35 is formed in a U-shape, it is connected rather than connecting the first side hole 33b and the second side hole 34d linearly. On the other hand, the length of the tube 35 can be increased, and the post-processing unit 3 can be made compact, which is advantageous for in-vehicle use.
　本実施形態の後処理ユニット３においては、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。これにより、尿素水が排ガスとの間で十分に攪拌混合されることが可能になり、尿素水の加水分解が更に促進される。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。 In the post-processing unit 3 of the present embodiment, the urea water added from the addition valve 36 passes through this long and folded connection pipe 35. Thereby, the urea water can be sufficiently stirred and mixed with the exhaust gas, and the hydrolysis of the urea water is further promoted. As a result, ammonia is efficiently generated, which is advantageous for improving the NOx purification rate in the NOx catalyst 10c.
　なお、本開示は、上述の実施形態に限定されるものではなく、本開示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 disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.
　本出願は、2016年3月3日付で出願された日本国特許出願（特願2016-041293）に基づくものであり、その内容はここに参照として取り込まれる。 This application is based on a Japanese patent application (Japanese Patent Application No. 2016-041293) filed on March 3, 2016, the contents of which are incorporated herein by reference.
　本開示の内燃機関の排ガス浄化装置は、後処理ユニットの熱がケーシングに奪われることを抑制し、後処理ユニットの触媒の温度低下を抑制することができるという点において有用である。 The exhaust gas purifying apparatus for an internal combustion engine according to the present disclosure is useful in that the heat of the aftertreatment unit is suppressed from being taken away by the casing, and the temperature decrease of the catalyst of the aftertreatment unit can be suppressed.
１　内燃機関
２　排気管
３　後処理ユニット
４　ケーシング
５　断熱材
６　入口側断熱シール部材
７　出口側断熱シール部材
３１　排ガス入口管
３２　排ガス出口管
４６　入口孔
４７　出口孔
１００　排ガス浄化装置
Ｓ１，Ｓ２　隙間 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust pipe 3 Post-processing unit 4 Casing 5 Heat insulating material 6 Inlet side heat insulating seal member 7 Outlet side heat insulating seal member 31 Exhaust gas inlet pipe 32 Exhaust gas outlet pipe 46 Inlet hole 47 Outlet hole 100 Exhaust gas purification apparatus S1, S2 Gap

Claims (3)

  1. 　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、
    　前記ケーシングに設けられ、前記後処理ユニットの排ガス入口管を外部に突出させるように前記排ガス入口管が隙間をもって挿通される入口孔と、
    　前記ケーシングに設けられ、前記後処理ユニットの排ガス出口管を外部に突出させるように前記排ガス出口管が隙間をもって挿通される出口孔と、
    　前記ケーシングの内周面上に設けられた断熱材と、
    　前記排ガス入口管と前記入口孔との隙間に設けられた入口側断熱シール部材と、
    　前記排ガス出口管と前記出口孔との隙間に設けられた出口側断熱シール部材と、を備える
    　内燃機関の排ガス浄化装置。     An 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 for housing the aftertreatment unit;
    An inlet hole provided in the casing, through which the exhaust gas inlet pipe is inserted with a gap so as to project the exhaust gas inlet pipe of the aftertreatment unit to the outside;
    An outlet hole provided in the casing, through which the exhaust gas outlet pipe is inserted with a gap so as to project the exhaust gas outlet pipe of the aftertreatment unit to the outside;
    A heat insulating material provided on the inner peripheral surface of the casing;
    An inlet-side heat insulating seal member provided in a gap between the exhaust gas inlet pipe and the inlet hole;
    An exhaust gas purification apparatus for an internal combustion engine, comprising: an outlet-side heat insulating seal member provided in a gap between the exhaust gas outlet pipe and the outlet hole.
  2. 　前記ケーシングの内周面のうち前記入口孔の周囲の部分には、前記ケーシングの内部に向かって突出し、前記入口側断熱シール部材を前記ケーシングに取り付けるための入口側支持部材が形成されており、
    　前記ケーシングの内周面のうち前記出口孔の周囲の部分には、前記ケーシングの内部に向かって突出し、前記出口側断熱シール部材を前記ケーシングに取り付けるための出口側支持部材が形成されている、
    　請求項１に記載の内燃機関の排ガス浄化装置。     Of the inner peripheral surface of the casing, a portion around the inlet hole protrudes toward the inside of the casing, and an inlet-side support member for attaching the inlet-side heat insulating seal member to the casing is formed.
    Of the inner peripheral surface of the casing, a portion around the outlet hole protrudes toward the inside of the casing, and an outlet-side support member for attaching the outlet-side heat insulating seal member to the casing is formed.
    The exhaust gas purification apparatus for an internal combustion engine according to claim 1.
  3. 　前記入口側支持部材は、リング状に形成され、前記入口孔より大きく、且つ、
    前記入口側断熱シール部材の外径より僅かに小さい内径を有し、
    　前記出口側支持部材は、リング状に形成され、前記出口孔より大きく、且つ、
    前記出口側断熱シール部材の外径より僅かに小さい内径を有する、
    　請求項２に記載の内燃機関の排ガス浄化装置。     The inlet side support member is formed in a ring shape, is larger than the inlet hole, and
    It has an inner diameter slightly smaller than the outer diameter of the inlet side heat insulating seal member,
    The outlet side support member is formed in a ring shape, is larger than the outlet hole, and
    Having an inner diameter slightly smaller than the outer diameter of the outlet side heat insulating seal member,
    The exhaust gas purification device for an internal combustion engine according to claim 2.
PCT/JP2017/007727 2016-03-03 2017-02-28 Exhaust gas purification device for internal combustion engine WO2017150513A1 (en)

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