JP5709493B2 - Engine exhaust purification system - Google Patents

Engine exhaust purification system Download PDF

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JP5709493B2
JP5709493B2 JP2010269999A JP2010269999A JP5709493B2 JP 5709493 B2 JP5709493 B2 JP 5709493B2 JP 2010269999 A JP2010269999 A JP 2010269999A JP 2010269999 A JP2010269999 A JP 2010269999A JP 5709493 B2 JP5709493 B2 JP 5709493B2
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exhaust
stirring plate
impact force
reducing agent
internal combustion
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JP2012117489A (en
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壽幸 矢内
壽幸 矢内
三宅　博
博 三宅
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UD Trucks Corp
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Description

本発明は、還元剤を用いて排気中の窒素酸化物（ＮＯｘ）を還元浄化するエンジンの排気浄化装置において、特に、排気中に噴射供給された液体還元剤又はその前駆体を攪拌する攪拌板へ堆積した析出物を除去する技術に関する。   The present invention relates to an exhaust purification device for an engine that reduces and purifies nitrogen oxide (NOx) in exhaust using a reducing agent, and in particular, a stirring plate that stirs a liquid reducing agent injected into the exhaust or a precursor thereof. The present invention relates to a technique for removing deposits deposited on the substrate.

エンジン排気中のＮＯｘを除去する触媒浄化システムとして、特許文献１に記載された排気浄化装置が提案されている。かかる排気浄化装置は、排気管に配設されたＮＯｘ還元触媒の排気上流に、エンジン運転状態に応じた液体還元剤又はその前駆体（以下液体還元剤で代表する）を噴射供給することで、ＮＯｘ還元触媒において排気中のＮＯｘと還元剤とを触媒還元反応させて、ＮＯｘを無害成分に浄化処理する。また、ＮＯｘ還元触媒上流の排気管内に噴射供給された液体還元剤又はその前駆体を攪拌する攪拌板を備えている。   As a catalyst purification system for removing NOx in engine exhaust, an exhaust purification device described in Patent Document 1 has been proposed. Such an exhaust purification device is configured to inject and supply a liquid reducing agent or a precursor thereof (hereinafter represented by a liquid reducing agent) according to the engine operating state to the upstream side of the NOx reduction catalyst disposed in the exhaust pipe. In the NOx reduction catalyst, NOx in the exhaust and a reducing agent are subjected to a catalytic reduction reaction to purify NOx into harmless components. In addition, a stirring plate is provided for stirring the liquid reducing agent or its precursor injected and supplied into the exhaust pipe upstream of the NOx reduction catalyst.

特許第２００９−１０８７２６号Patent No. 2009-108726

この種の排気浄化装置においては、市街地走行等、エンジンの負荷が低いところでの走行では、排気温度が低く、尿素水等の液体還元剤に由来する物質が排気管内に析出することがある。
このように、液体還元剤由来の物質が析出される走行が繰り返されると、析出物が前記攪拌板に堆積して排気通路開口面積が減少して排気流通抵抗の増大によりエンジン出力の低下の惧れがある。 In this type of exhaust emission control device, when the engine is traveling at a low load, such as in urban areas, the exhaust temperature is low, and substances derived from a liquid reducing agent such as urea water may be deposited in the exhaust pipe.
In this way, when the traveling in which the substance derived from the liquid reducing agent is deposited is repeated, the deposit accumulates on the stirring plate, the exhaust passage opening area is reduced, and the exhaust flow resistance is increased, so that the engine output may be reduced. There is.

本発明は、このような従来の課題に着目してなされたもので、攪拌板に堆積した析出物を除去し、もって良好な運転性を維持できるようにした内燃機関の排気浄化装置を提供することを目的とする。   The present invention has been made paying attention to such a conventional problem, and provides an exhaust emission control device for an internal combustion engine that removes deposits deposited on a stirring plate and maintains good operability. For the purpose.

このため、本発明に係る内燃機関の排気浄化装置は、
内燃機関の排気管に配設され、還元剤を用いて窒素酸化物を還元浄化する還元触媒と、
前記還元触媒の排気上流に液体還元剤又はその前駆体を噴射供給する還元剤噴射ノズルと、
前記還元剤噴射ノズルと前記還元触媒との間に位置する排気管に配設されて、還元剤噴射ノズルから噴射された液体還元剤又はその前駆体を攪拌する攪拌板と、
前記攪拌板に衝撃力を与えて、前記攪拌板に堆積した析出物を除去する衝撃力付与機構と、
排気温度ｔが所定値ｔ０未満のときの積算時間が所定値以上のときに攪拌板への析出物の堆積量が所定量以上に達したと推定し、前記衝撃力付与機構を駆動する制御手段と、
を含んで構成されたことを特徴とする。 For this reason, the exhaust gas purification apparatus for an internal combustion engine according to the present invention is
A reduction catalyst disposed in an exhaust pipe of an internal combustion engine for reducing and purifying nitrogen oxides using a reducing agent;
A reducing agent injection nozzle that injects and supplies a liquid reducing agent or a precursor thereof upstream of the exhaust of the reduction catalyst;
A stirring plate that is disposed in an exhaust pipe positioned between the reducing agent injection nozzle and the reduction catalyst and that stirs the liquid reducing agent or its precursor injected from the reducing agent injection nozzle;
An impact force imparting mechanism that applies an impact force to the stirring plate to remove deposits deposited on the stirring plate;
Control means for driving the impact force applying mechanism by estimating that the accumulated amount of the precipitate on the stirring plate has reached a predetermined amount or more when the accumulated time when the exhaust temperature t is less than the predetermined value t0 is a predetermined value or more. When,
It is characterized by including.

本発明によれば、排気温度ｔが所定値ｔ０未満のときの積算時間が所定値以上のときに攪拌板への析出物の堆積量が所定量以上に達したと推定し、衝撃力付与機構によって攪拌板に衝撃を与えて攪拌板に堆積した析出物を除去して、析出物堆積量の増大を抑制することができ、もって、排気通路開口面積の減少を抑制して良好な運転性能を維持することができる。また、排気温度に基づいて析出量を高精度に推定し、除去制御性能を高めることができる。 According to the present invention, when the accumulated time when the exhaust temperature t is less than the predetermined value t0 is greater than or equal to the predetermined value, it is estimated that the amount of deposits deposited on the stirring plate has reached the predetermined amount or more, and the impact force imparting mechanism The impact on the stir plate can be removed by this to remove the deposit deposited on the stir plate, thereby suppressing an increase in the amount of deposit deposited, and thus reducing the decrease in the exhaust passage opening area and achieving good operating performance. Can be maintained. Moreover, the amount of precipitation can be estimated with high accuracy based on the exhaust temperature, and the removal control performance can be enhanced.

本発明の実施形態を示すエンジン排気系のシステム図である。It is a system diagram of an engine exhaust system showing an embodiment of the present invention. 本発明に係る衝撃力付与機構の構成を示す図である。It is a figure which shows the structure of the impact-force provision mechanism which concerns on this invention. 攪拌板を示す正面図である。It is a front view which shows a stirring plate. 上記衝撃力付与機構及びヒータの制御を示すフローチャートである。It is a flowchart which shows control of the said impact-force provision mechanism and a heater.

以下、本発明の実施の形態について、詳細に説明する。
図１は本発明の実施形態を示すエンジン排気系のシステム図である。
ディーゼルエンジン（エンジン本体）１の排気マニホールド２下流側の排気通路（排気管）３には、排気浄化装置を装備させるため、上流側の第１ケーシング４と、下流側の第２ケーシング５と、これらのケーシング４、５間の連通路６とが設けられる。 Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a system diagram of an engine exhaust system showing an embodiment of the present invention.
In order to equip the exhaust passage (exhaust pipe) 3 on the downstream side of the exhaust manifold 2 of the diesel engine (engine body) 1 with an exhaust purification device, the first casing 4 on the upstream side, the second casing 5 on the downstream side, A communication path 6 between the casings 4 and 5 is provided.

第１ケーシング４内には、前段にディーゼル酸化触媒（ＤＯＣ；Diesel Oxidation Catalyst ）７が収納され、後段にディーゼルパティキュレートフィルタ（以下「ＤＰＦ」という）８が収納されている。
ＤＰＦ８は、排気中の粒子状物質であるＰＭ（Particulate Matter）を捕集するフィルタであり、例えば、多孔質セラミックのハニカム構造の担体からなり、上流側と下流側とを連通する通路が多数並設されると共に、隣接する通路同士において上流側と下流側とが交互に封止されたウォールフロータイプのフィルタである。 In the first casing 4, a diesel oxidation catalyst (DOC; Diesel Oxidation Catalyst) 7 is accommodated in the front stage, and a diesel particulate filter (hereinafter referred to as “DPF”) 8 is accommodated in the rear stage.
The DPF 8 is a filter that collects PM (Particulate Matter) that is particulate matter in the exhaust gas. For example, the DPF 8 is made of a porous ceramic honeycomb structure carrier, and has many passages that connect the upstream side and the downstream side. And a wall flow type filter in which the upstream side and the downstream side are alternately sealed in adjacent passages.

酸化触媒７は、排気中のＮＯを酸化させてＮＯ２を生成し、このＮＯ２を酸化剤としてＤＰＦ８に供給すると共に、酸化熱を発生させて、下流側のＤＰＦ８を昇温させる。これにより、ＤＰＦ８に捕集されているＰＭは、酸化触媒７から供給されたＮＯ２と反応して酸化し、ＤＰＦ８の連続再生が行われる。
第２ケーシング５内には、前段にアンモニアを還元剤としてＮＯｘを還元する機能を有するＳＣＲ触媒９が収納され、後段にＳＣＲ触媒９から流出したアンモニアを酸化してＮ２とする酸化触媒としての機能を有するアンモニア酸化触媒１０が収納されている。尚、「ＳＣＲ」は、Selective Catalytic Reduction の略語である。 The oxidation catalyst 7 is NO in the exhaust is oxidized to generate NO 2, it is supplied to the DPF8 the NO 2 as an oxidizing agent, to generate oxidation heat, raising the temperature of the DPF8 downstream. As a result, the PM trapped in the DPF 8 reacts with the NO 2 supplied from the oxidation catalyst 7 and is oxidized, and the DPF 8 is continuously regenerated.
In the second casing 5, an SCR catalyst 9 having a function of reducing NOx using ammonia as a reducing agent is housed in the front stage, and as an oxidation catalyst that oxidizes ammonia flowing out from the SCR catalyst 9 and converts it to N 2 in the rear stage. The ammonia oxidation catalyst 10 having a function is accommodated. “SCR” is an abbreviation for Selective Catalytic Reduction.

そして、第２ケーシング５上流の連通路６には、ＳＣＲ触媒９へ向けて、還元剤（アンモニア）の前駆体としての尿素水溶液（以下「尿素水」という）を加圧空気と共に噴射する尿素水噴射ノズル１１が設けられている。尚、尿素水は、図示しない尿素水タンクから噴射量制御用の制御モジュール１２を介してノズル１１へ供給され、制御モジュール１２は電子制御ユニット（ＥＣＵ）５０により制御される。   A urea aqueous solution (hereinafter referred to as “urea water”) as a reducing agent (ammonia) precursor is injected into the communication passage 6 upstream of the second casing 5 together with the pressurized air toward the SCR catalyst 9. An injection nozzle 11 is provided. The urea water is supplied from a urea water tank (not shown) to the nozzle 11 via the control module 12 for controlling the injection amount, and the control module 12 is controlled by an electronic control unit (ECU) 50.

尿素水噴射ノズル１１から噴射された尿素水は、排気の熱により加水分解してアンモニアとなる。ＳＣＲ触媒９は、このようにして生成されたアンモニアを吸着し、吸着したアンモニアを還元剤として、ＮＯｘとアンモニア（ＮＨ３）とを選択的に還元反応させ、ＮＯｘを無害な水（Ｈ２Ｏ）と窒素（Ｎ２）へ浄化する。ここにおいて、ＳＣＲ触媒９と尿素水噴射ノズル１１とでＮＯｘ還元装置を構成している。 The urea water injected from the urea water injection nozzle 11 is hydrolyzed by the heat of the exhaust to become ammonia. The SCR catalyst 9 adsorbs the ammonia generated in this manner, selectively reduces NOx and ammonia (NH 3 ) using the adsorbed ammonia as a reducing agent, and converts NOx into harmless water (H 2 O). ) And nitrogen (N 2 ). Here, the SCR catalyst 9 and the urea water injection nozzle 11 constitute a NOx reduction device.

また、連通路６の尿素水噴射ノズル１１とＳＣＲ触媒９との間の部分には、還元剤としてのアンモニアを含んだ排気を攪拌する攪拌板１３が配設される。攪拌板１３は、例えば、後述するように複数の開口を排気が通過する方向をそれぞれ変化させるガイド壁を持たせた形状に形成されている。
かかる攪拌板１３により、アンモニアを含んだ排気は攪拌されて略均一に拡散されるため、ＳＣＲ触媒９に供給されるアンモニア濃度のむらを抑制し、ＳＣＲ触媒９によるＮＯｘ浄化効率を向上させることができる。 Further, a stirring plate 13 for stirring exhaust gas containing ammonia as a reducing agent is disposed in a portion of the communication path 6 between the urea water injection nozzle 11 and the SCR catalyst 9. For example, the agitating plate 13 is formed in a shape having a guide wall that changes the direction in which the exhaust passes through a plurality of openings, as will be described later.
With the stirring plate 13, the exhaust gas containing ammonia is stirred and diffused substantially uniformly. Therefore, unevenness in the concentration of ammonia supplied to the SCR catalyst 9 can be suppressed, and the NOx purification efficiency by the SCR catalyst 9 can be improved. .

ここで、既述したように、特に、低負荷走行運転時等で排気温度が低下すると、尿素水が攪拌板１３の表面に液状で付着しやすく、付着した尿素水の水分が蒸発することにより、還元剤由来の物質などが析出し、攪拌板１３表面に堆積する。かかる現象の繰り返しにより、攪拌板１３表面の析出物堆積量が増大すると、排気通路面積が減少して排気流通抵抗の増大によりエンジン出力の低下の惧れがある。   Here, as described above, particularly when the exhaust gas temperature is lowered during a low-load running operation or the like, the urea water tends to adhere to the surface of the stirring plate 13 in a liquid state, and the moisture of the attached urea water evaporates. The substance derived from the reducing agent is deposited and deposited on the surface of the stirring plate 13. If the amount of deposit accumulated on the surface of the stirring plate 13 increases due to the repetition of such a phenomenon, the exhaust passage area decreases, and the engine output may decrease due to an increase in exhaust flow resistance.

そこで、本実施形態では、攪拌板に衝撃を与えて攪拌板に堆積した析出物を振り落として除去する衝撃力付与機構２１を、以下のように配設する。
図２は、衝撃力付与機構２１の構成を示す。
攪拌板１３は、図３に示すように円筒状リング部材１３Ａと、その内側に排気流通方向に対して交互に傾斜方向を変えて列設された複数のガイドプレート１３Ｂとを有して形成される。さらに、円筒状リング部材１３Ａの直径方向に回転軸１３ａを設け、該回転軸１３ａの両端部を、連通路６壁を貫通させて、攪拌板１３を回転軸１３ａ周り回動自由に支持する。 Therefore, in the present embodiment, the impact force applying mechanism 21 that applies an impact to the stirring plate and shakes off the deposits deposited on the stirring plate is disposed as follows.
FIG. 2 shows the configuration of the impact force applying mechanism 21.
As shown in FIG. 3, the stirring plate 13 is formed by having a cylindrical ring member 13A and a plurality of guide plates 13B arranged inside the ring member 13A while changing the inclination direction alternately with respect to the exhaust flow direction. The Further, a rotary shaft 13a is provided in the diameter direction of the cylindrical ring member 13A, and both ends of the rotary shaft 13a are passed through the wall of the communication path 6 so that the stirring plate 13 is supported to freely rotate around the rotary shaft 13a.

回転軸１３ａの連通路６壁外側に突出する一方の端部にレバー１４の一端部を連結すると共に、該レバー１４の他端部にエアシリンダ等のアクチュエータ１５の駆動軸１５ａ端部を連結し、駆動軸１５ａの伸縮により、レバー１４の揺動を介して回転軸１３ａ回りに攪拌板１３を回動させるように構成する。
また、駆動軸１５ａの伸張時に、駆動軸１５ａを連結したレバー１４の端部が突き当たる位置にストッパ１６を配設する。 One end of the lever 14 is connected to one end of the rotating shaft 13a that protrudes outside the wall of the communication path 6, and the end of the drive shaft 15a of the actuator 15 such as an air cylinder is connected to the other end of the lever 14. The agitating plate 13 is configured to rotate around the rotation shaft 13a through the swing of the lever 14 by the expansion and contraction of the drive shaft 15a.
Further, the stopper 16 is disposed at a position where the end of the lever 14 connected to the drive shaft 15a abuts when the drive shaft 15a is extended.

かかる構成を備えた衝撃力付与機構の作用を説明する。
アクチュエータ１５を駆動して駆動軸１５ａを伸張すると、レバー１４を介して攪拌板１３が回動し、駆動軸１５ａがストッパ１６に突き当たると急停止し、そのとき生じる衝撃力により、攪拌板１３に堆積された析出物が振り落とされて除去される。
次いで、アクチュエータ１５の駆動を停止（エアシリンダの場合は、圧縮空気を放出）すると、アクチュエータ１５に内蔵されたリターンスプリングにより駆動軸１５ａが高速で引き戻され、初期位置まで戻されて急停止する際に、再度衝撃力が生じ、攪拌板１３に堆積された析出物が振り落とされて除去される。 The operation of the impact force imparting mechanism having such a configuration will be described.
When the actuator 15 is driven to extend the drive shaft 15a, the stirring plate 13 rotates via the lever 14, and stops suddenly when the drive shaft 15a hits the stopper 16, and the impact force generated at that time causes the stirring plate 13 to move. The deposited deposit is shaken off and removed.
Next, when the drive of the actuator 15 is stopped (in the case of an air cylinder, compressed air is released), the drive shaft 15a is pulled back at a high speed by a return spring built in the actuator 15 and returned to the initial position to suddenly stop. In addition, an impact force is generated again, and the deposit deposited on the stirring plate 13 is shaken off and removed.

かかる駆動・駆動停止操作は、１回でもよいが、数回繰り返せば、より多くの析出物を除去することができる。
上記衝撃力付与機構２１を攪拌板１３に所定量以上の析出物が堆積したときに駆動するように制御するため、図１に示すように、析出物堆積量を推定するための排気温度及び排気温度を検出するための排気温度センサ１７及び排気圧力センサ１８を、尿素水噴射ノズル１１近傍の連通路６壁に配設する。 Such a drive / drive stop operation may be performed once, but if it is repeated several times, more precipitates can be removed.
In order to control the impact force imparting mechanism 21 to be driven when a predetermined amount or more of deposits accumulates on the stirring plate 13, as shown in FIG. 1, the exhaust temperature and the exhaust for estimating the deposit accumulation amount An exhaust temperature sensor 17 and an exhaust pressure sensor 18 for detecting the temperature are disposed on the wall of the communication passage 6 near the urea water injection nozzle 11.

また、衝撃力付与機構２１によって除去され連通路６壁に落下した尿素などの析出物を加熱してガス化しアンモニアに転化させるヒータ１９を攪拌板１３下流直下の連通路６底壁に配設する。
次に、電子制御ユニット（ＥＣＵ）５０による衝撃力付与機構２１及びヒータ１９の制御を、図４のフローチャートに基づいて説明する。 Further, a heater 19 for heating and gasifying the precipitates such as urea removed by the impact force applying mechanism 21 and falling on the wall of the communication path 6 to be converted into ammonia is disposed on the bottom wall of the communication path 6 immediately below the stirring plate 13. .
Next, control of the impact force applying mechanism 21 and the heater 19 by the electronic control unit (ECU) 50 will be described based on the flowchart of FIG.

このフローは、所定時間周期で実行される。
ステップＳ１では、排気温度ｔが、所定温度ｔ０未満であるかを判定する。所定温度ｔ０は、例えば、液体還元剤由来の析出物の融点とし、したがって、所定温度ｔ０未満では、液体還元剤由来の物質が析出する。
ステップＳ１で所定温度ｔ０未満と判定されたときは、ステップＳ２へ進んで積算カウンタの値Ｃをインクリメントする（Ｃ←Ｃ＋１）。 This flow is executed at a predetermined time period.
In step S1, it is determined whether the exhaust temperature t is lower than a predetermined temperature t0. The predetermined temperature t0 is, for example, the melting point of the precipitate derived from the liquid reducing agent, and therefore, the substance derived from the liquid reducing agent is deposited at a temperature lower than the predetermined temperature t0.
When it is determined in step S1 that the temperature is lower than the predetermined temperature t0, the process proceeds to step S2 to increment the value C of the integration counter (C ← C + 1).

そして、ステップＳ３で、積算カウンタの値Ｃが所定値Ｃ０以上に達したか、つまり、液体還元剤由来の物質が析出している時間の積算値が所定時間以上に達して、攪拌板１３への析出物の堆積量が所定値以上になったかを判定する。
また、積算カウンタの値Ｃが所定値Ｃ０に達する前は、ステップＳ４へ進み、攪拌板１３上流の排気圧力Ｐが所定値Ｐ０以上であるかを判定する。排気圧力Ｐが所定値Ｐ０以上のときは、攪拌板１３への析出物の堆積量が増大して攪拌板１３の通路面積が減少し、その結果、排気抵抗の増大によって排気圧力Ｐが所定値Ｐ０以上に増大したと推定される。 Then, in step S3, whether the value C of the integration counter has reached a predetermined value C0 or more, that is, the integrated value of the time during which the substance derived from the liquid reducing agent is deposited has reached a predetermined time or more, and It is determined whether or not the amount of deposits of deposits exceeds a predetermined value.
Further, before the value C of the integration counter reaches the predetermined value C0, the process proceeds to step S4, and it is determined whether the exhaust pressure P upstream of the stirring plate 13 is equal to or higher than the predetermined value P0. When the exhaust pressure P is greater than or equal to the predetermined value P0, the amount of deposits deposited on the stirring plate 13 increases and the passage area of the stirring plate 13 decreases, and as a result, the exhaust pressure P increases to a predetermined value due to an increase in exhaust resistance. It is estimated that it increased to P0 or more.

そこで、ステップＳ３で積算カウンタの値Ｃが所定値Ｃ０に達したと判定されたとき、または、ステップＳ排気圧力Ｐが所定値Ｐ０以上に増大したと判定されたとき、ステップＳ５へ進み、攪拌板１３に堆積した析出物を除去するため、前記衝撃力付与機構２１を駆動する。すなわち、上述したようにアクチュエータ１５をＯＮ，ＯＦＦする。あるいは、このＯＮ，ＯＦＦ操作を数回繰り返す。   Therefore, when it is determined in step S3 that the value C of the integration counter has reached the predetermined value C0, or when it is determined that the exhaust pressure P of the step S has increased to the predetermined value P0 or more, the process proceeds to step S5 and stirring is performed. In order to remove the deposit deposited on the plate 13, the impact force applying mechanism 21 is driven. That is, the actuator 15 is turned ON / OFF as described above. Alternatively, this ON / OFF operation is repeated several times.

これにより、アクチュエータ１５のＯＮ時に駆動軸１５が伸張し、レバー１４がストッパ１６に突き当たって停止した時に付与される衝撃、次いで、ＯＦＦして駆動軸１５ａが引き込まれて停止した時に付与される衝撃により、攪拌板１３に堆積した析出物が振るい落とされて除去される。
ステップＳ６では、上記のようにして攪拌板１３から連通路６壁上に振り落とされた析出物を加熱する。これにより、固形の析出物がガス化され、アンモニアガスとしてＳＣＲ触媒９に供給される。 As a result, when the actuator 15 is turned on, the drive shaft 15 expands, and an impact is applied when the lever 14 comes into contact with the stopper 16 and stops. Then, an impact is applied when the drive shaft 15a is pulled and stopped. Thus, the deposit deposited on the stirring plate 13 is shaken off and removed.
In step S6, the precipitate shaken off on the wall of the communication path 6 from the stirring plate 13 as described above is heated. Thereby, the solid precipitate is gasified and supplied to the SCR catalyst 9 as ammonia gas.

このようにすれば、攪拌板１３に析出物が所定量以上堆積する毎に攪拌板１３に衝撃力が付与されて析出物を除去することができ、排気通路面積の減少による排気抵抗の増大、ひいてはエンジン出力の低減、燃費悪化を抑制して良好なエンジン性能を維持することができる。 In this way, every time deposits are deposited on the stirring plate 13 by a predetermined amount or more, impact force is applied to the stirring plate 13 to remove the precipitates, and the exhaust resistance is increased by reducing the exhaust passage area. As a result, it is possible to maintain good engine performance by suppressing engine output reduction and fuel consumption deterioration .

また、攪拌板の形状は、上記実施形態の形状に限らず、攪拌機能を有する任意の形状であってよい。
また、衝撃力付与機構は、上記実施形態に限られるものではなく、例えば、攪拌板にバイブレータを連結し、加振することによって析出物を振り落とす構成であってもよい。 Further, the shape of the stirring plate is not limited to the shape of the above embodiment, and may be any shape having a stirring function.
Further, the impact force imparting mechanism is not limited to the above-described embodiment, and for example, a structure in which a precipitate is shaken off by connecting a vibrator to a stirring plate and vibrating the same.

１ ディーゼルエンジン
３ 排気通路
６ 連通路
９ ＳＣＲ触媒
１０ アンモニア酸化触媒
１１ 尿素水噴射ノズル
１２ 制御モジュール
１３ 攪拌板
１３ａ 回転軸
１４ レバー
１５ アクチュエータ
１５ａ 駆動軸
１６ ストッパ
１７ 排気温度センサ
１８ 排気圧力センサ
１９ ヒータ
２１ 衝撃付与機構
５０ 電子制御ユニット（ＥＣＵ） DESCRIPTION OF SYMBOLS 1 Diesel engine 3 Exhaust passage 6 Communication passage 9 SCR catalyst 10 Ammonia oxidation catalyst 11 Urea water injection nozzle 12 Control module 13 Stirring plate 13a Rotating shaft 14 Lever 15 Actuator 15a Drive shaft 16 Stopper 17 Exhaust temperature sensor 18 Exhaust pressure sensor 19 Heater 21 Impact applying mechanism 50 Electronic control unit (ECU)

Claims (5)

内燃機関の排気管に配設され、還元剤を用いて窒素酸化物を還元浄化する還元触媒と、
前記還元触媒の排気上流に液体還元剤又はその前駆体を噴射供給する還元剤噴射ノズルと、
前記還元剤噴射ノズルと前記還元触媒との間に位置する排気管に配設されて、還元剤噴射ノズルから噴射された液体還元剤又はその前駆体を攪拌する攪拌板と、
前記攪拌板に衝撃力を与えて、前記攪拌板に堆積した析出物を除去する衝撃力付与機構と、
排気温度ｔが所定値ｔ０未満のときの積算時間が所定値以上のときに攪拌板への析出物の堆積量が所定量以上に達したと推定し、前記衝撃力付与機構を駆動する制御手段と、
を含んで構成されたことを特徴とする内燃機関の排気浄化装置。 A reduction catalyst disposed in an exhaust pipe of an internal combustion engine for reducing and purifying nitrogen oxides using a reducing agent;
A reducing agent injection nozzle that injects and supplies a liquid reducing agent or a precursor thereof upstream of the exhaust of the reduction catalyst;
A stirring plate that is disposed in an exhaust pipe positioned between the reducing agent injection nozzle and the reduction catalyst and that stirs the liquid reducing agent or its precursor injected from the reducing agent injection nozzle;
An impact force imparting mechanism that applies an impact force to the stirring plate to remove deposits deposited on the stirring plate;
Control means for driving the impact force applying mechanism by estimating that the accumulated amount of the precipitate on the stirring plate has reached a predetermined amount or more when the accumulated time when the exhaust temperature t is less than the predetermined value t0 is a predetermined value or more. When,
An exhaust emission control device for an internal combustion engine, comprising: 前記衝撃力付与機構は、排気管に回動自由に支持された前記攪拌板を所定角度回動し、急停止させたときに生じる衝撃力を与える機構である請求項１に記載の内燃機関の排気浄化装置。   2. The internal combustion engine according to claim 1, wherein the impact force imparting mechanism is a mechanism that imparts an impact force that is generated when the stirring plate that is rotatably supported by the exhaust pipe is rotated by a predetermined angle and suddenly stopped. Exhaust purification device. 前記衝撃力付与機構は、前記攪拌板を加振して衝撃力を与える機構である請求項１に記載の内燃機関の排気浄化装置。   The exhaust purification device of an internal combustion engine according to claim 1, wherein the impact force applying mechanism is a mechanism that applies an impact force by vibrating the stirring plate. 前記制御手段は、排気圧力にも基づいて前記攪拌板に堆積した析出物の堆積量を推定し、該排気圧力に基づいて攪拌板への析出物の堆積量が所定量以上に達したと推定したときにも、前記衝撃力付与機構を駆動する請求項１〜請求項３のいずれか１つに記載の内燃機関の排気浄化装置。 The control means estimates the amount of deposits deposited on the stirring plate based on the exhaust pressure, and estimates that the amount of deposits deposited on the stirring plate reaches a predetermined amount or more based on the exhaust pressure. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the impact force applying mechanism is driven even when the engine is operated . 前記攪拌板から排気管内に除去された析出物を、加熱して分解する加熱手段を含んで構成される請求項１〜請求項４のいずれか１つに記載の内燃機関の排気浄化装置。 The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 4 , comprising heating means for heating and decomposing the precipitate removed from the stirring plate into the exhaust pipe.
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