WO2017150582A1 - 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
WO2017150582A1
WO2017150582A1 PCT/JP2017/008009 JP2017008009W WO2017150582A1 WO 2017150582 A1 WO2017150582 A1 WO 2017150582A1 JP 2017008009 W JP2017008009 W JP 2017008009W WO 2017150582 A1 WO2017150582 A1 WO 2017150582A1
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WO
WIPO (PCT)
Prior art keywords
catalyst
upstream
downstream
exhaust gas
internal combustion
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PCT/JP2017/008009
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French (fr)
Japanese (ja)
Inventor
幸博 川島
直 水上
Original Assignee
いすゞ自動車株式会社
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Application filed by いすゞ自動車株式会社 filed Critical いすゞ自動車株式会社
Priority to CN201780013789.6A priority Critical patent/CN108779697A/en
Publication of WO2017150582A1 publication Critical patent/WO2017150582A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • 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
    • 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 purifying device for an internal combustion engine having a plurality of catalysts provided in series with an exhaust pipe.
  • a vehicle equipped with an internal combustion engine is equipped with an exhaust gas purification device.
  • the exhaust gas purification device is provided in series with the exhaust pipe and has a plurality of catalysts for purifying harmful substances in the exhaust gas.
  • the catalyst is poisoned by poisoning components such as S (sulfur), HC (hydrocarbon), and P (phosphorus) contained in the exhaust gas. Both of these poisoning components are derived from fuel and engine oil. S and HC are known to eliminate poisoning under high temperature conditions where the exhaust gas temperature is a predetermined temperature or higher. In other words, poisoning by S and HC is a temporary that can be recovered.
  • S sulfur
  • HC hydrocarbon
  • P phosphorus
  • P is contained in engine oil.
  • this engine oil burns and P is contained in exhaust gas, P adheres to the catalyst and causes P poisoning.
  • catalyst deterioration due to P poisoning tends to proceed.
  • the present disclosure provides an exhaust gas purification apparatus for an internal combustion engine that can suppress a decrease in the performance of the entire catalyst even when P poisoning occurs.
  • An exhaust gas purification apparatus for an internal combustion engine having an exhaust pipe and a plurality of catalysts provided in series with the exhaust pipe,
  • engine oil containing phosphorus is circulated
  • the catalyst located on the most upstream side of the plurality of catalysts has an upstream part located from the upstream end to the downstream side by a predetermined distance, and a downstream part located downstream from the upstream part,
  • the upstream portion and the downstream portion include a catalytic metal,
  • the upstream portion has less catalytic metal loading per unit length than the downstream portion.
  • An exhaust gas purification apparatus for an internal combustion engine having an exhaust pipe and a plurality of catalysts provided in series with the exhaust pipe,
  • engine oil containing phosphorus is circulated
  • the catalyst located on the most upstream side of the plurality of catalysts has an upstream part located from the upstream end to the downstream side by a predetermined distance, and a downstream part located downstream from the upstream part,
  • the upstream portion and the downstream portion include a catalytic metal,
  • the upstream portion further includes barium.
  • the catalyst located on the most upstream side may be an oxidation catalyst.
  • the plurality of catalysts may be provided in an aftertreatment unit provided in the middle of the exhaust pipe,
  • the post-processing unit is A tubular first catalyst casing containing at least one catalyst;
  • a tubular second catalyst casing disposed in parallel to and downstream of the first catalyst casing and having at least one catalyst disposed therein;
  • a connecting pipe disposed at a position between the first catalyst casing and the second catalyst casing and connecting a downstream end of the first catalyst casing and an upstream end of the second catalyst casing;
  • a connecting pipe having a folded portion that extends from the rear to the front along the U, and is folded back into a U shape and extends rearward.
  • An addition valve arranged to add urea water from the rear to the front from the upstream side of the folded portion toward the folded portion; You may have
  • the catalyst located on the most upstream side may be a catalyst located on the most upstream side in the first catalyst casing.
  • an excellent effect is exhibited that it is possible to suppress a decrease in the performance of the entire catalyst even when P poisoning occurs.
  • FIG. 1 is a schematic configuration diagram illustrating an exhaust gas purifying apparatus according to an embodiment of the present disclosure.
  • 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.
  • the exhaust gas purification apparatus 100 includes an exhaust pipe 2 that allows exhaust gas of an internal combustion engine (engine) 1 to pass therethrough, and a plurality of catalysts 10 that are provided in the middle of the exhaust pipe 2 and purify the exhaust gas.
  • the post-processing unit 3 and a casing 4 that houses the post-processing unit 3 are included.
  • 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 that connects the first catalyst casing 33 and the second catalyst casing 34 and an addition valve 36 that adds 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 formed of a so-called continuous regeneration type DPF with a catalyst having a noble metal (catalyst metal) such as Pt supported on the inner wall thereof.
  • a catalyst having a noble metal (catalyst metal) such as Pt supported on the inner wall thereof.
  • 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 contained in the catalyst 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 corresponds to a portion from X1 to X2 in the drawing
  • the second portion 35b corresponds to 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. .
  • the connecting pipe 35 By forming the connecting pipe 35 by being folded in a U shape in this way, the pipe length of the connecting pipe 35 becomes longer than connecting the first side hole 33b and the second side hole 34d linearly.
  • 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 an airtight manner.
  • a heat insulating material 5 such as glass wool is laid on almost the entire inner 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 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.
  • the front surface 45 of the casing 4 is formed with an inlet hole 42a through which the exhaust gas inlet pipe 31 of the post-processing unit 3 is inserted and an outlet hole 42b through which the exhaust gas outlet pipe 32 is inserted at the left and right positions.
  • the exhaust pipe 2 is provided with a plurality of catalysts 10 (the oxidation catalyst 10a, the DPF 10b, the NOx catalyst 10c, and the ammonia oxidation catalyst 10d in order from the upstream side) in series. Yes.
  • the oxidation catalyst 10a is located on the most upstream side.
  • engine oil containing P (phosphorus) is circulated. Therefore, the engine oil is burned simultaneously with the fuel in the cylinder 11, and the exhaust gas produced thereby contains P.
  • the exhaust gas containing P is first supplied to the most upstream oxidation catalyst 10a. At this time, P adheres to the oxidation catalyst 10a, covers the noble metal (catalyst metal) of the oxidation catalyst 10a, and poisons the oxidation catalyst 10a.
  • the degree of P poisoning increases as the use time of the oxidation catalyst 10a, specifically, the mileage of the vehicle increases.
  • the present embodiment adopts the following configuration to minimize the performance degradation of the entire catalyst even when P poisoning occurs.
  • the oxidation catalyst 10a has an upstream end 51 located on the front side, a downstream end 52 located on the rear side, and a central axis C extending in the front-rear direction.
  • the oxidation catalyst 10 a includes an upstream portion 53 from the upstream end 51 to the downstream side of the predetermined distance L ⁇ b> 1, and a downstream portion 54 that is located downstream of the upstream portion 53.
  • the total length of the oxidation catalyst 10a is L
  • the length of the upstream portion 53 is L1
  • the length L1 of the upstream portion 53 is set so as to include a region where the adhesion amount of P is relatively large through experiments and the like. For example, it is set so as to include a region where the adhesion amount of P becomes a predetermined value or more at the time of a predetermined travel distance. Preferably, the length L1 is set to 5 to 38% of the total length L. It has been found that more P is attached to the upstream side.
  • the oxidation catalyst 10a has a honeycomb-shaped carrier made of a heat-resistant ceramic or metal such as cordierite, and a coat layer coated on the surface of the carrier.
  • a large number of fine particles of a noble metal referred to as catalyst metal
  • Pt platinum
  • the catalyst metal is contained in the coat layers of both the upstream portion 53 and the downstream portion 54.
  • the amount of catalyst metal supported per unit length is smaller in the upstream portion 53 than in the downstream portion 54.
  • the said carrying amount can also be paraphrased as a carrying density.
  • the carrier is immersed in a slurry (aqueous solution) in which fine particles of the catalyst metal are dispersed and containing a promoter component such as ceria (CeO 2 ), and then the carrier is dried and calcined, whereby the carrier surface A coat layer is formed on the substrate (so-called wash coat method).
  • a slurry aqueous solution
  • a promoter component such as ceria (CeO 2 )
  • the carrier is dried and calcined, whereby the carrier surface A coat layer is formed on the substrate (so-called wash coat method).
  • wash coat method two slurries with different catalyst metal concentrations are prepared, the support portion corresponding to the downstream portion 54 is immersed in the high concentration slurry, and the support portion corresponding to the upstream portion 53 is immersed in the low concentration slurry.
  • the upstream portion 53 having a low carrying density and the downstream portion 54 having a high carrying density it is possible to easily form the upstream portion 53 having a low carrying density and the downstream portion 54 having a high carrying density.
  • the support portion corresponding to the downstream portion 54 is immersed twice in one slurry having a constant catalyst metal concentration, and the support portion corresponding to the upstream portion 53 is immersed once.
  • the upstream part 53 and the downstream part 54 can also be easily formed by reducing the number of immersions of the above-mentioned ones than the number of immersions.
  • 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 adds urea water from the rear to the front from the bent portion L to the folded portion U.
  • the exhaust gas mixed with the urea water is turned 180 ° rearward at the folded portion U, flows to the rear second portion 35b, is turned 90 ° along the bent shape of the second portion, and the second side. It flows into the second catalyst casing 34 through the hole 34b.
  • the urea water is hydrolyzed to produce ammonia while being mixed with the exhaust gas and evaporating.
  • 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 exhaust gas containing P is first supplied to the oxidation catalyst 10a from P contained in the engine oil.
  • a large amount of P contained in the exhaust gas adheres to the vicinity of the upstream end 51 of the oxidation catalyst 10a, and particularly adheres more in the upstream portion 53 than in the downstream portion 54.
  • P adheres P covers the coating layer and the catalyst metal, reduces the catalytic action of the catalyst metal, and poisons the catalyst.
  • the upstream portion 53 has a smaller amount (supported density) of catalytic metal per unit length than the downstream portion 54, the degree of P poisoning of the oxidation catalyst 10a when viewed as a whole of the oxidation catalyst 10a. , It can be reduced as compared with the case where both loading amounts are the same.
  • connection pipe 35 is formed in a U-shape, the first side hole 33b and the second side hole 34d are connected linearly.
  • the length of the connecting pipe 35 can be increased while the post-processing unit 3 can be made compact, it 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 catalytic metal loading (supporting density) per unit length is less in the upstream portion 53 than in the downstream portion 54.
  • Ba barium
  • the upstream portion 53 it was found that when Ba is contained, the adhesion amount of P is reduced and the progress of P poisoning of the catalyst is delayed. Therefore, by including Ba in the upstream portion 53, the degree of P poisoning of the upstream portion 53 can be reduced and performance degradation in the entire oxidation catalyst 10a can be suppressed to a minimum.
  • the loading density is arbitrary, and may be the same as the loading density of the downstream portion 54, for example. This is because the degree of P poisoning of the upstream portion 53 can be reduced even in this way.
  • Ba is mixed in advance in the slurry in which the carrier portion corresponding to the upstream portion 53 is immersed.
  • Embodiments including post-processing units other than those described above are possible.
  • an embodiment without a post-processing unit is also possible.

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  • Chemical Kinetics & Catalysis (AREA)
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  • General Engineering & Computer Science (AREA)
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  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

An exhaust gas purification device 100 for an internal combustion engine 1 according to the present invention is provided with a plurality of catalysts 10 which are provided in series in an exhaust pipe 2. Phosphorus-containing engine oil is circulated in the internal combustion engine. The catalyst 10a positioned furthest upstream among the plurality of catalysts is provided with: an upstream section 53 which extends a prescribed distance L1 downstream from an upstream end 51; and a downstream section 54 positioned further downstream than the upstream section. The upstream section and the downstream section include a catalytic metal. The upstream section supports a smaller amount of the catalytic metal per unit length than the downstream section.

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、排気管に直列に設けられた複数の触媒を有する内燃機関の排ガス浄化装置に関する。 The present disclosure relates to an exhaust gas purifying device for an internal combustion engine having a plurality of catalysts provided in series with an exhaust pipe.
　一般に、内燃機関を搭載した車両には排ガス浄化装置が備えられている。排ガス浄化装置は、排気管に直列に設けられ、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。 Generally, a vehicle equipped with an internal combustion engine is equipped with an exhaust gas purification device. The exhaust gas purification device is provided in series with the exhaust pipe and has a plurality of catalysts for purifying harmful substances in the exhaust gas.
日本国特開２００２－３０９９３２号公報Japanese Patent Laid-Open No. 2002-309932
　触媒は、排ガスに含まれるＳ（硫黄）、ＨＣ（炭化水素）、Ｐ（リン）といった被毒成分により被毒する。これら被毒成分は、ともに燃料やエンジンオイルに由来するものである。ＳとＨＣについては、排ガス温度が所定温度以上という高温条件下で被毒解消することが知られている。つまりＳとＨＣによる被毒は回復可能な一時的なものである。 The catalyst is poisoned by poisoning components such as S (sulfur), HC (hydrocarbon), and P (phosphorus) contained in the exhaust gas. Both of these poisoning components are derived from fuel and engine oil. S and HC are known to eliminate poisoning under high temperature conditions where the exhaust gas temperature is a predetermined temperature or higher. In other words, poisoning by S and HC is a temporary that can be recovered.
　しかしながら、Ｐによる被毒は、排ガス温度が高温となっても解消しない。つまり触媒に付着したＰは、排ガス温度が高温となっても触媒から脱離されない。従ってＰによる被毒は、回復不能な恒久的なものである。これは触媒の恒久的劣化につながる。Ｐ被毒が生じると必然的に触媒浄化能力が低下してしまう。 However, poisoning by P does not disappear even if the exhaust gas temperature becomes high. That is, P adhering to the catalyst is not desorbed from the catalyst even when the exhaust gas temperature becomes high. Therefore, poisoning by P is permanent and cannot be recovered. This leads to permanent deterioration of the catalyst. When P poisoning occurs, the catalyst purification ability inevitably decreases.
　通常、Ｐはエンジンオイルに含まれ、このエンジンオイルが燃焼してＰが排ガスに含まれると、Ｐが触媒に付着してＰ被毒を生じさせる。特に、メーカー推奨でない、Ｐを比較的多く含むエンジンオイルが使用されてしまうと、Ｐ被毒による触媒劣化が進行し易い。 Normally, P is contained in engine oil. When this engine oil burns and P is contained in exhaust gas, P adheres to the catalyst and causes P poisoning. In particular, when engine oil containing a relatively large amount of P, which is not recommended by the manufacturer, is used, catalyst deterioration due to P poisoning tends to proceed.
　他方、本発明者は鋭意研究の結果、複数の触媒のうち最上流側に位置する触媒、特にその上流端付近にＰが多く付着することを見出した。よってこの特性を活かし、たとえＰ被毒が生じたとしても、触媒全体の性能低下を最小限に抑制する手法が望まれる。 On the other hand, as a result of intensive studies, the present inventor has found that a large amount of P adheres to a catalyst located on the most upstream side among a plurality of catalysts, particularly in the vicinity of its upstream end. Therefore, a technique is desired that takes advantage of this characteristic and suppresses the performance degradation of the entire catalyst even if P poisoning occurs.
　本開示は、Ｐ被毒が生じた場合でも触媒全体の性能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。 The present disclosure provides an exhaust gas purification apparatus for an internal combustion engine that can suppress a decrease in the performance of the entire catalyst even when P poisoning occurs.
　本開示の一の態様によれば、
　排気管と、前記排気管に直列に設けられた複数の触媒とを有する内燃機関の排ガス浄化装置であって、
　前記内燃機関には、リンを含むエンジンオイルが循環され、
　前記複数の触媒のうち最上流側に位置する触媒は、上流端から所定距離下流側までに位置する上流側部分と、前記上流側部分より下流側に位置する下流側部分とを有し、
　前記上流側部分と前記下流側部分は、触媒金属を含み、
　前記上流側部分は前記下流側部分より、単位長さ当たりにおける触媒金属の担持量が少ない。 According to one aspect of the present disclosure,
An exhaust gas purification apparatus for an internal combustion engine having an exhaust pipe and a plurality of catalysts provided in series with the exhaust pipe,
In the internal combustion engine, engine oil containing phosphorus is circulated,
The catalyst located on the most upstream side of the plurality of catalysts has an upstream part located from the upstream end to the downstream side by a predetermined distance, and a downstream part located downstream from the upstream part,
The upstream portion and the downstream portion include a catalytic metal,
The upstream portion has less catalytic metal loading per unit length than the downstream portion.
　本開示の他の態様によれば、
　排気管と、前記排気管に直列に設けられた複数の触媒とを有する内燃機関の排ガス浄化装置であって、
　前記内燃機関には、リンを含むエンジンオイルが循環され、
　前記複数の触媒のうち最上流側に位置する触媒は、上流端から所定距離下流側までに位置する上流側部分と、前記上流側部分より下流側に位置する下流側部分とを有し、
　前記上流側部分と前記下流側部分は、触媒金属を含み、
　前記上流側部分はバリウムをさらに含む。 According to another aspect of the present disclosure,
An exhaust gas purification apparatus for an internal combustion engine having an exhaust pipe and a plurality of catalysts provided in series with the exhaust pipe,
In the internal combustion engine, engine oil containing phosphorus is circulated,
The catalyst located on the most upstream side of the plurality of catalysts has an upstream part located from the upstream end to the downstream side by a predetermined distance, and a downstream part located downstream from the upstream part,
The upstream portion and the downstream portion include a catalytic metal,
The upstream portion further includes barium.
　前記最上流側に位置する触媒は、酸化触媒であってもよい。 The catalyst located on the most upstream side may be an oxidation catalyst.
　前記複数の触媒は、前記排気管の途中に設けられた後処理ユニットに設けられてもよく、
　前記後処理ユニットは、
　少なくとも一つの触媒を内設する管状の第１触媒ケーシングと、
　前記第１触媒ケーシングに並列してかつその下流側に配置され、少なくとも一つの触媒を内設する管状の第２触媒ケーシングと、
　前記第１触媒ケーシングと前記第２触媒ケーシングとの間の位置に配置され、前記第１触媒ケーシングの下流端と前記第２触媒ケーシングの上流端とを連結する連結管であって、排気流れ方向に沿って後方から前方に向かって延び、Ｕ字状に折り返されて後方に延びる折り返し部分を有する連結管と、
　前記折り返し部分の上流側から前記折り返し部分に向かって、後方から前方に尿素水を添加するように配置された添加弁と、
　を備えてもよく、
　前記最上流側に位置する触媒は、前記第１触媒ケーシング内において最上流側に位置する触媒でああってもよい。 The plurality of catalysts may be provided in an aftertreatment unit provided in the middle of the exhaust pipe,
The post-processing unit is
A tubular first catalyst casing containing at least one catalyst;
A tubular second catalyst casing disposed in parallel to and downstream of the first catalyst casing and having at least one catalyst disposed therein;
A connecting pipe disposed at a position between the first catalyst casing and the second catalyst casing and connecting a downstream end of the first catalyst casing and an upstream end of the second catalyst casing; A connecting pipe having a folded portion that extends from the rear to the front along the U, and is folded back into a U shape and extends rearward.
An addition valve arranged to add urea water from the rear to the front from the upstream side of the folded portion toward the folded portion;
You may have
The catalyst located on the most upstream side may be a catalyst located on the most upstream side in the first catalyst casing.
　本開示によれば、Ｐ被毒が生じた場合でも触媒全体の性能低下を抑制することができるという、優れた効果が発揮される。 According to the present disclosure, an excellent effect is exhibited that it is possible to suppress a decrease in the performance of the entire catalyst even when P poisoning occurs.
図１は、本開示の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 purifying apparatus according to an embodiment of the present disclosure.
　以下、添付図面に基づいて、本開示の実施形態を説明する。図１は、本開示の実施形態に係る内燃機関の排ガス浄化装置を示す概略構成図である。 Hereinafter, embodiments of the present disclosure will be described with reference to 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.
　図１に示すように、排ガス浄化装置１００は、内燃機関（エンジン）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, the exhaust gas purification apparatus 100 includes an exhaust pipe 2 that allows exhaust gas of an internal combustion engine (engine) 1 to pass therethrough, and a plurality of catalysts 10 that are provided in the middle of the exhaust pipe 2 and purify the exhaust gas. The post-processing unit 3 and a casing 4 that houses the post-processing unit 3 are included.
　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から排出された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とを備える。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 that connects the first catalyst casing 33 and the second catalyst casing 34 and an addition valve 36 that adds 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（触媒金属）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に含まれるものとする。 The DPF 10b is formed of a so-called continuous regeneration type DPF with a catalyst having a noble metal (catalyst metal) such as Pt 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 contained in the catalyst 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、第１触媒ケーシング３３と第２触媒ケーシング３４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までの部分に該当し、第２部分３５ｂは、図中のＹ１からＹ２までの部分に該当する。 More specifically, the connecting pipe 35 extends from the first side hole 33b toward the second side hole 34b (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 corresponds to a portion from X1 to X2 in the drawing, and the second portion 35b corresponds to 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。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. . By forming the connecting pipe 35 by being folded in a U shape in this way, the pipe length of the connecting pipe 35 becomes longer than connecting the first side hole 33b and the second side hole 34d linearly.
　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全体を気密に覆う。ケーシング４の内面上ほぼ全体には、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 an airtight manner. A heat insulating material 5 such as glass wool is laid on almost the entire inner 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 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、左右の位置に、後処理ユニット３の排ガス入口管３１が挿通される入口孔４２ａと、排ガス出口管３２が挿通される出口孔４２ｂとが形成される。 The front surface 45 of the casing 4 is formed with an inlet hole 42a through which the exhaust gas inlet pipe 31 of the post-processing unit 3 is inserted and an outlet hole 42b through which the exhaust gas outlet pipe 32 is inserted at the left and right positions.
　このように、本実施形態に係る排ガス浄化装置１００においては、排気管２に複数の触媒１０（上流側から順に酸化触媒１０ａ、ＤＰＦ１０ｂ、ＮＯｘ触媒１０ｃおよびアンモニア酸化触媒１０ｄ）が直列に設けられている。そして最上流側に酸化触媒１０ａが位置されている。 Thus, in the exhaust gas purification apparatus 100 according to the present embodiment, the exhaust pipe 2 is provided with a plurality of catalysts 10 (the oxidation catalyst 10a, the DPF 10b, the NOx catalyst 10c, and the ammonia oxidation catalyst 10d in order from the upstream side) in series. Yes. The oxidation catalyst 10a is located on the most upstream side.
　本実施形態のエンジン１には、Ｐ（リン）を含むエンジンオイルが循環される。従って、シリンダ１１内で燃料と同時にエンジンオイルも燃焼され、これによってできた排ガスにはＰが含まれる。このＰを含む排ガスが、最初に最上流側の酸化触媒１０ａに供給される。このときＰが酸化触媒１０ａに付着し、酸化触媒１０ａの貴金属（触媒金属）を覆い、酸化触媒１０ａをＰ被毒させる。なおＰ被毒度合いは、酸化触媒１０ａの使用時間、具体的には車両の走行距離が増加するにつれて、増加するものである。 In the engine 1 of this embodiment, engine oil containing P (phosphorus) is circulated. Therefore, the engine oil is burned simultaneously with the fuel in the cylinder 11, and the exhaust gas produced thereby contains P. The exhaust gas containing P is first supplied to the most upstream oxidation catalyst 10a. At this time, P adheres to the oxidation catalyst 10a, covers the noble metal (catalyst metal) of the oxidation catalyst 10a, and poisons the oxidation catalyst 10a. The degree of P poisoning increases as the use time of the oxidation catalyst 10a, specifically, the mileage of the vehicle increases.
　他方、本発明者は鋭意研究の結果、酸化触媒１０ａの上流端付近にＰが多く付着することを見出した。よってこの特性を活かし、本実施形態は下記の構成を採用することにより、たとえＰ被毒が生じた場合でも、触媒全体の性能低下を最小限に抑制することとしている。 On the other hand, as a result of intensive studies, the present inventor has found that a large amount of P adheres near the upstream end of the oxidation catalyst 10a. Therefore, taking advantage of this characteristic, the present embodiment adopts the following configuration to minimize the performance degradation of the entire catalyst even when P poisoning occurs.
　図１に示すように、酸化触媒１０ａは、前側に位置する上流端５１と、後側に位置する下流端５２と、前後方向に延びる中心軸Ｃとを有する。また酸化触媒１０ａは、上流端５１から所定距離Ｌ１下流側までの上流側部分５３と、上流側部分５３より下流側に位置する下流側部分５４とを有する。酸化触媒１０ａの全長はＬ、上流側部分５３の長さはＬ１、下流側部分５４の長さはＬ２である（Ｌ＝Ｌ１＋Ｌ２）。 As shown in FIG. 1, the oxidation catalyst 10a has an upstream end 51 located on the front side, a downstream end 52 located on the rear side, and a central axis C extending in the front-rear direction. The oxidation catalyst 10 a includes an upstream portion 53 from the upstream end 51 to the downstream side of the predetermined distance L <b> 1, and a downstream portion 54 that is located downstream of the upstream portion 53. The total length of the oxidation catalyst 10a is L, the length of the upstream portion 53 is L1, and the length of the downstream portion 54 is L2 (L = L1 + L2).
　上流側部分５３の長さＬ１は、実験等を通じ、Ｐの付着量が比較的多くなる領域を含むように設定される。例えば、所定の走行距離の時点においてＰの付着量が所定値以上となる領域を含むように設定される。好ましくは長さＬ１は、全長Ｌの５～３８％に設定される。なおＰは上流側ほど多く付着することが判明している。 The length L1 of the upstream portion 53 is set so as to include a region where the adhesion amount of P is relatively large through experiments and the like. For example, it is set so as to include a region where the adhesion amount of P becomes a predetermined value or more at the time of a predetermined travel distance. Preferably, the length L1 is set to 5 to 38% of the total length L. It has been found that more P is attached to the upstream side.
　酸化触媒１０ａは、コーディエライト等の耐熱性セラミックまたは金属から形成されたハニカム状の担体と、担体の表面にコートされたコート層とを有する。コート層には、主触媒成分であるＰｔ（白金）等の貴金属（触媒金属という）の微粒子が多数分散配置されている。 The oxidation catalyst 10a has a honeycomb-shaped carrier made of a heat-resistant ceramic or metal such as cordierite, and a coat layer coated on the surface of the carrier. In the coating layer, a large number of fine particles of a noble metal (referred to as catalyst metal) such as Pt (platinum) as a main catalyst component are dispersedly arranged.
　ここで、上流側部分５３と下流側部分５４の両方のコート層に触媒金属が含まれる。しかしながら、単位長さ当たりにおける触媒金属の担持量は、上流側部分５３の方が下流側部分５４より少ない。なお当該担持量は担持密度と言い換えることもできる。 Here, the catalyst metal is contained in the coat layers of both the upstream portion 53 and the downstream portion 54. However, the amount of catalyst metal supported per unit length is smaller in the upstream portion 53 than in the downstream portion 54. In addition, the said carrying amount can also be paraphrased as a carrying density.
　酸化触媒１０ａの製作に関し、触媒金属の微粒子が分散され且つセリア（ＣｅＯ２）等の助触媒成分を含むスラリー（水溶液）に、担体を浸漬し、その後担体を乾燥、焼成することで担体表面上にコート層を形成する（所謂ウォッシュコート法）。このとき、触媒金属の濃度が異なる二つのスラリーを用意し、下流側部分５４に相当する担体部分を高濃度のスラリーに浸漬し、上流側部分５３に相当する担体部分を低濃度のスラリーに浸漬する。こうすることにより、担持密度の低い上流側部分５３と担持密度の高い下流側部分５４とを容易に形成することができる。なお代替的に、触媒金属濃度が一定の一つのスラリーに、下流側部分５４に相当する担体部分を２回浸漬し、上流側部分５３に相当する担体部分を１回浸漬するといったように、後者の浸漬回数を前者の浸漬回数より減らすことでも、上流側部分５３と下流側部分５４とを容易に形成できる。 Regarding the production of the oxidation catalyst 10a, the carrier is immersed in a slurry (aqueous solution) in which fine particles of the catalyst metal are dispersed and containing a promoter component such as ceria (CeO 2 ), and then the carrier is dried and calcined, whereby the carrier surface A coat layer is formed on the substrate (so-called wash coat method). At this time, two slurries with different catalyst metal concentrations are prepared, the support portion corresponding to the downstream portion 54 is immersed in the high concentration slurry, and the support portion corresponding to the upstream portion 53 is immersed in the low concentration slurry. To do. By doing so, it is possible to easily form the upstream portion 53 having a low carrying density and the downstream portion 54 having a high carrying density. Alternatively, in the latter case, the support portion corresponding to the downstream portion 54 is immersed twice in one slurry having a constant catalyst metal concentration, and the support portion corresponding to the upstream portion 53 is immersed once. The upstream part 53 and the downstream part 54 can also be easily formed by reducing the number of immersions of the above-mentioned ones than the number of immersions.
　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.
　添加弁３６は、折れ曲がり部分Ｌから折り返し部分Ｕに向かって、後方から前方に尿素水を添加する。この尿素水が混入された排ガスは、折り返し部分Ｕにて後方へ１８０°方向転換し、後方の第２部分３５ｂへ流れ、第２部分の折れ曲がり形状に沿って９０°方向転換し、第２側孔３４ｂを通じて第２触媒ケーシング３４内へ流入する。この過程で尿素水は、排ガスと混合して蒸発しつつ、加水分解されてアンモニアを生成する。 The addition valve 36 adds urea water from the rear to the front from the bent portion L to the folded portion U. The exhaust gas mixed with the urea water is turned 180 ° rearward at the folded portion U, flows to the rear second portion 35b, is turned 90 ° along the bent shape of the second portion, and the second side. It flows into the second catalyst casing 34 through the hole 34b. In this process, the urea water is hydrolyzed to produce ammonia while being mixed with the exhaust gas and evaporating.
　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.
　ところで、酸化触媒１０ａには、エンジンオイルに含まれるＰに由来して、Ｐを含む排ガスが最初に供給される。この排ガス中に含まれるＰは、酸化触媒１０ａの上流端５１付近に多く付着し、特に上流側部分５３において下流側部分５４よりも多く付着する。Ｐが付着すると、Ｐはコート層ひいては触媒金属を覆い、触媒金属による触媒作用を低下させ、触媒をＰ被毒させる。 Incidentally, the exhaust gas containing P is first supplied to the oxidation catalyst 10a from P contained in the engine oil. A large amount of P contained in the exhaust gas adheres to the vicinity of the upstream end 51 of the oxidation catalyst 10a, and particularly adheres more in the upstream portion 53 than in the downstream portion 54. When P adheres, P covers the coating layer and the catalyst metal, reduces the catalytic action of the catalyst metal, and poisons the catalyst.
　しかし、上流側部分５３の方が下流側部分５４より単位長さ当たりにおける触媒金属の担持量（担持密度）が少ないので、酸化触媒１０ａ全体で見たときの酸化触媒１０ａのＰ被毒度合いを、両方の担持量を同じとした場合よりも低減することができる。 However, since the upstream portion 53 has a smaller amount (supported density) of catalytic metal per unit length than the downstream portion 54, the degree of P poisoning of the oxidation catalyst 10a when viewed as a whole of the oxidation catalyst 10a. , It can be reduced as compared with the case where both loading amounts are the same.
　すなわち、酸化触媒１０ａにおける新品時の元々の性能（ＨＣまたはＣＯの浄化率）が、上流側部分５３において下流側部分５４よりも低いので、この性能の低い上流側部分５３にＰ被毒が生じても、その酸化触媒１０ａ全体への影響（ダメージ）を少なくすることができる。よって結果的に、Ｐ被毒が生じた場合でも、触媒全体の性能低下を最小限に抑制することができる。 That is, since the original performance (HC or CO purification rate) of the oxidation catalyst 10a when new is lower in the upstream portion 53 than in the downstream portion 54, P poisoning occurs in the upstream portion 53 having low performance. However, the influence (damage) on the entire oxidation catalyst 10a can be reduced. As a result, even when P poisoning occurs, it is possible to minimize the performance degradation of the entire catalyst.
　なお、本実施形態の後処理ユニット３の他の利点に関して、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。 In addition, regarding the other advantage of the post-processing unit 3 of this embodiment, since the connection pipe 35 is formed in a U-shape, the first side hole 33b and the second side hole 34d are connected linearly. However, since the length of the connecting pipe 35 can be increased while the post-processing unit 3 can be made compact, it 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.
　以上、本開示の実施形態を詳細に述べたが、本開示は次のような他の実施形態も可能である。 Although the embodiment of the present disclosure has been described in detail above, the present disclosure can be applied to other embodiments as follows.
　（１）上記実施形態では、単位長さ当たりにおける触媒金属担持量（担持密度）を、下流側部分５４よりも上流側部分５３において少なくした。一方、追加的または代替的に、上流側部分５３にＢａ（バリウム）を含めてもよい。本発明者の研究結果によると、Ｂａが含まれている場合、Ｐの付着量が低減し、触媒のＰ被毒の進行が遅れることが判明した。従って上流側部分５３にＢａを含めることによっても、上流側部分５３のＰ被毒度合いを少なくし、酸化触媒１０ａ全体での性能低下を最小限に抑制することができる。 (1) In the above embodiment, the catalytic metal loading (supporting density) per unit length is less in the upstream portion 53 than in the downstream portion 54. On the other hand, in addition or alternatively, Ba (barium) may be included in the upstream portion 53. According to the research result of the present inventor, it was found that when Ba is contained, the adhesion amount of P is reduced and the progress of P poisoning of the catalyst is delayed. Therefore, by including Ba in the upstream portion 53, the degree of P poisoning of the upstream portion 53 can be reduced and performance degradation in the entire oxidation catalyst 10a can be suppressed to a minimum.
　なお、Ｂａを含める場合、上流側部分５３に触媒金属が含まれていれば、その担持密度は任意であり、例えば下流側部分５４の担持密度と同じであってもよい。こうしても上流側部分５３のＰ被毒度合いを低減できるからである。製作に関し、Ｂａは、上流側部分５３に相当する担体部分を浸漬するスラリーに予め混入される。 In addition, when Ba is included, as long as the catalyst metal is contained in the upstream portion 53, the loading density is arbitrary, and may be the same as the loading density of the downstream portion 54, for example. This is because the degree of P poisoning of the upstream portion 53 can be reduced even in this way. Regarding the production, Ba is mixed in advance in the slurry in which the carrier portion corresponding to the upstream portion 53 is immersed.
　（２）上記以外の後処理ユニットを備えた実施形態が可能である。また、特に後処理ユニットといったものを備えない実施形態も可能である。 (2) Embodiments including post-processing units other than those described above are possible. In addition, an embodiment without a post-processing unit is also possible.
　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。本開示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開示の思想に包含されるあらゆる変形例や応用例、均等物が本開示に含まれる。従って本開示は、限定的に解釈されるべきではなく、本開示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 above-described embodiments can be combined partially or wholly unless there is a particular contradiction. The embodiment of the present disclosure is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present disclosure defined by the claims. Therefore, the present disclosure should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea 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2016-041295）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. 2016-041295) 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によれば、Ｐ被毒が生じた場合でも触媒全体の性能低下を抑制することができる。 According to the exhaust gas purification apparatus for an internal combustion engine of the present disclosure, even when P poisoning occurs, it is possible to suppress a decrease in the performance of the entire catalyst.
　１　内燃機関
　２　排気管
　３　後処理ユニット
　１０　触媒
　１０ａ　酸化触媒
　３３　第１触媒ケーシング
　３４　第２触媒ケーシング
　３５　連結管
　３６　添加弁
　５１　上流端
　５３　上流側部分
　５４　下流側部分
　１００　排ガス浄化装置
　Ｌ１　所定距離（長さ） DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust pipe 3 Post-processing unit 10 Catalyst 10a Oxidation catalyst 33 1st catalyst casing 34 2nd catalyst casing 35 Connection pipe 36 Addition valve 51 Upstream end 53 Upstream part 54 Downstream part 100 Exhaust gas purification apparatus L1 predetermined distance ( length)

Claims (5)

  1. 　排気管と、前記排気管に直列に設けられた複数の触媒とを有する内燃機関の排ガス浄化装置であって、
    　前記内燃機関には、リンを含むエンジンオイルが循環され、
    　前記複数の触媒のうち最上流側に位置する触媒は、上流端から所定距離下流側までの上流側部分と、前記上流側部分より下流側に位置する下流側部分とを有し、
    　前記上流側部分と前記下流側部分は、触媒金属を含み、
    　前記上流側部分は前記下流側部分より、単位長さ当たりにおける触媒金属の担持量が少ない。     An exhaust gas purification apparatus for an internal combustion engine having an exhaust pipe and a plurality of catalysts provided in series with the exhaust pipe,
    In the internal combustion engine, engine oil containing phosphorus is circulated,
    The catalyst located on the most upstream side of the plurality of catalysts has an upstream part from an upstream end to a downstream side by a predetermined distance, and a downstream part located downstream from the upstream part,
    The upstream portion and the downstream portion include a catalytic metal,
    The upstream portion has less catalytic metal loading per unit length than the downstream portion.
  2. 　排気管と、前記排気管に直列に設けられた複数の触媒とを有する内燃機関の排ガス浄化装置であって、
    　前記内燃機関には、リンを含むエンジンオイルが循環され、
    　前記複数の触媒のうち最上流側に位置する触媒は、上流端から所定距離下流側までの上流側部分と、前記上流側部分より下流側に位置する下流側部分とを有し、
    　前記上流側部分と前記下流側部分は、触媒金属を含み、
    　前記上流側部分はバリウムをさらに含む。     An exhaust gas purification apparatus for an internal combustion engine having an exhaust pipe and a plurality of catalysts provided in series with the exhaust pipe,
    In the internal combustion engine, engine oil containing phosphorus is circulated,
    The catalyst located on the most upstream side of the plurality of catalysts has an upstream part from an upstream end to a downstream side by a predetermined distance, and a downstream part located downstream from the upstream part,
    The upstream portion and the downstream portion include a catalytic metal,
    The upstream portion further includes barium.
  3. 　前記最上流側に位置する触媒は、酸化触媒である
    　請求項１に記載の内燃機関の排ガス浄化装置。     The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the catalyst located on the most upstream side is an oxidation catalyst.
  4. 　前記最上流側に位置する触媒は、酸化触媒である
    　請求項２に記載の内燃機関の排ガス浄化装置。     The exhaust gas purification apparatus for an internal combustion engine according to claim 2, wherein the catalyst located on the most upstream side is an oxidation catalyst.
  5. 　前記複数の触媒は、前記排気管の途中に設けられた後処理ユニットに設けられ、
    　前記後処理ユニットは、
    　少なくとも一つの触媒を内設する管状の第１触媒ケーシングと、
    　前記第１触媒ケーシングに並列してかつその下流側に配置され、少なくとも一つの触媒を内設する管状の第２触媒ケーシングと、
    　前記第１触媒ケーシングと前記第２触媒ケーシングとの間の位置に配置され、前記第１触媒ケーシングの下流端と前記第２触媒ケーシングの上流端とを連結する連結管であって、排気流れ方向に沿って後方から前方に向かって延び、Ｕ字状に折り返されて後方に延びる折り返し部分を有する連結管と、
    　前記折り返し部分の上流側から前記折り返し部分に向かって、後方から前方に尿素水を添加するように配置された添加弁と、
    　を備え、
    　前記最上流側に位置する触媒は、前記第１触媒ケーシング内において最上流側に位置する触媒である、請求項１～３のいずれか一項に記載の内燃機関の排ガス浄化装置。     The plurality of catalysts are provided in an aftertreatment unit provided in the middle of the exhaust pipe,
    The post-processing unit is
    A tubular first catalyst casing containing at least one catalyst;
    A tubular second catalyst casing disposed in parallel to and downstream of the first catalyst casing and having at least one catalyst disposed therein;
    A connecting pipe disposed at a position between the first catalyst casing and the second catalyst casing and connecting a downstream end of the first catalyst casing and an upstream end of the second catalyst casing; A connecting pipe having a folded portion that extends from the rear to the front along the U, and is folded back into a U shape and extends rearward.
    An addition valve arranged to add urea water from the rear to the front from the upstream side of the folded portion toward the folded portion;
    With
    The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the catalyst located on the most upstream side is a catalyst located on the most upstream side in the first catalyst casing.
PCT/JP2017/008009 2016-03-03 2017-02-28 Exhaust gas purification device for internal combustion engine WO2017150582A1 (en)

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