JP2007205267A - Exhaust emission control device - Google Patents

Exhaust emission control device Download PDF

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JP2007205267A
JP2007205267A JP2006025795A JP2006025795A JP2007205267A JP 2007205267 A JP2007205267 A JP 2007205267A JP 2006025795 A JP2006025795 A JP 2006025795A JP 2006025795 A JP2006025795 A JP 2006025795A JP 2007205267 A JP2007205267 A JP 2007205267A
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particulate filter
exhaust gas
reduction catalyst
control device
exhaust
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Ichiro Tsumagari
一郎 津曲
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Hino Motors Ltd
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Hino Motors Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2053—By-passing catalytic reactors, e.g. to prevent overheating
    • 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
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
    • 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
    • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
    • F01N3/106—Auxiliary oxidation catalysts
    • 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
    • F01N3/2066—Selective catalytic reduction [SCR]
    • 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
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • 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
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Materials Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device which inhibits temperature drop of NOx conversion catalyst and improves NOx conversion rate, also inhibits deterioration of fuel economy at the time of regeneration of a particulate filter, and prevents thermal deterioration of the NOx conversion catalyst. <P>SOLUTION: A selective reduction type catalyst 6 and a particulate filter 5 are provided in a middle of an exhaust pipe 3, and there is provided a change over valve 20 for changing over to a normal operation position A making exhaust gas 2 exhausted from a diesel engine 1 pass through the selective reduction type catalyst 6 and the particulate filter 5 in this order, and a filter regeneration position B in which leading the exhaust gas 2 directly to the particulate filter 5 without passing through the selective reduction type catalyst 6. The change over valve 20 is changed over to the normal operation position A at the time of normal operation and is changed over to the filter regeneration position B at the time of regeneration of the particulate filter 5 by control signal 20a from a control device 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、排気浄化装置に関するものである。   The present invention relates to an exhaust emission control device.

一般に、ディーゼルエンジンから排出されるパティキュレート（Particulate Matter：粒子状物質）は、炭素質から成る煤と、高沸点炭化水素成分から成るＳＯＦ分（Soluble Organic Fraction：可溶性有機成分）とを主成分とし、更に微量のサルフェート（ミスト状硫酸成分）を含んだ組成を成すものであるが、この種のパティキュレートの低減対策としては、ディーゼルエンジンからの排気ガスが流通する排気管の途中に、パティキュレートフィルタを装備することが行われている。   In general, particulate matter (particulate matter) emitted from diesel engines is mainly composed of soot made of carbonaceous matter and SOF (Soluble Organic Fraction) consisting of high-boiling hydrocarbon components. In addition, it has a composition containing a trace amount of sulfate (misty sulfuric acid component). As a measure for reducing this type of particulates, the particulates are placed in the middle of the exhaust pipe through which the exhaust gas from the diesel engine flows. Equipped with a filter.

又、ディーゼルエンジンにおいては、前記排気管の途中に装備した排気浄化用触媒としてのＮＯx低減触媒により排気浄化を図ることが行われており、この種のＮＯx低減触媒としては、酸素共存下でも選択的にＮＯxを還元剤と反応させる性質を備えた選択還元型触媒、或いは、排気空燃比がリーンの時に排気ガス中のＮＯxを酸化して硝酸塩の状態で一時的に吸蔵し、排気ガス中のＯ2濃度が低下した時に未燃ＨＣやＣＯ等の介在によりＮＯxを分解放出して還元浄化する性質を備えたＮＯx吸蔵還元触媒等が知られている。 Further, in a diesel engine, exhaust purification is performed by a NOx reduction catalyst as an exhaust purification catalyst installed in the middle of the exhaust pipe, and this type of NOx reduction catalyst is selected even in the presence of oxygen. Selective reduction type catalyst having the property of reacting NOx with a reducing agent, or when exhaust air-fuel ratio is lean, NOx in exhaust gas is oxidized and temporarily stored in the form of nitrate, A NOx occlusion reduction catalyst or the like having the property of decomposing and releasing NOx through the intervention of unburned HC, CO or the like to reduce and purify when the O 2 concentration decreases is known.

図２は従来における排気浄化装置の一例を示す概略図であって、ディーゼルエンジン１からの排気ガス２が流通する排気管３の途中に、前段酸化触媒４と、パティキュレートフィルタ５と、ＮＯx低減触媒としての選択還元型触媒６とを上流側から順次配設すると共に、前記選択還元型触媒６の入側へ尿素水等の還元剤を添加する還元剤添加装置７を装備したものである。   FIG. 2 is a schematic view showing an example of a conventional exhaust purification device. In the middle of an exhaust pipe 3 through which the exhaust gas 2 from the diesel engine 1 flows, a pre-stage oxidation catalyst 4, a particulate filter 5, and NOx reduction. A selective reduction catalyst 6 as a catalyst is sequentially arranged from the upstream side, and a reducing agent addition device 7 for adding a reducing agent such as urea water to the inlet side of the selective reduction catalyst 6 is provided.

前記還元剤添加装置７は、還元剤としての尿素水８が貯留された尿素水タンク９を備え、該尿素水タンク９から延びる尿素水供給ライン１０の途中に、尿素水タンク９の尿素水８を圧送する供給ポンプ１１と、該供給ポンプ１１によって圧送される尿素水８を噴射ノズル１２から噴射させるインジェクタ１３とを設けてなる構成を有している。   The reducing agent adding device 7 includes a urea water tank 9 in which urea water 8 as a reducing agent is stored, and urea water 8 in the urea water tank 9 is provided in the middle of a urea water supply line 10 extending from the urea water tank 9. And a injector 13 for injecting urea water 8 pressure-fed by the supply pump 11 from the injection nozzle 12.

前記還元剤添加装置７の供給ポンプ１１とインジェクタ１３とに対しては、制御装置１４から駆動指令信号１１ａと開弁指令信号１３ａとが出力されるようになっており、該制御装置１４から出力される駆動指令信号１１ａと開弁指令信号１３ａとに基づく、前記供給ポンプ１１の駆動とインジェクタ１３の開弁作動とにより、尿素水８の添加量が適切に制御されるようになっている。   A drive command signal 11 a and a valve opening command signal 13 a are output from the control device 14 to the supply pump 11 and the injector 13 of the reducing agent adding device 7, and output from the control device 14. The amount of urea water 8 added is appropriately controlled by driving the supply pump 11 and opening the injector 13 based on the drive command signal 11a and the valve opening command signal 13a.

尚、前記制御装置１４においては、図示していないエンジン制御コンピュータ（ＥＣＵ：Electronic Control Unit）との間でディーゼルエンジン１の回転数及び負荷が遣り取りされ、これらから判断される現在の運転状態に基づきＮＯxの発生量が推定され、その推定されたＮＯxの発生量に見合う尿素水８の添加量が算出されて必要量の尿素水８の添加が実行されるようになっている。   In the control device 14, the rotational speed and load of the diesel engine 1 are exchanged with an engine control computer (ECU: Electronic Control Unit) (not shown), and based on the current operating state determined from these. The amount of NOx generated is estimated, the amount of urea water 8 added corresponding to the estimated amount of NOx generated is calculated, and the required amount of urea water 8 is added.

尚、図２中、１５はディーゼルエンジン１の吸気管であって、該吸気管１５途中には、前記排気管３途中に設けられたタービン１６によって駆動されるコンプレッサ１７が設けられ、該タービン１６とコンプレッサ１７とからターボチャージャ１８が構成されると共に、前記コンプレッサ１７より下流側における吸気管１５途中には、インタクーラ１９が設けられている。   In FIG. 2, reference numeral 15 denotes an intake pipe of the diesel engine 1, and a compressor 17 driven by a turbine 16 provided in the middle of the exhaust pipe 3 is provided in the middle of the intake pipe 15. A turbocharger 18 is constituted by the compressor 17 and an intercooler 19 is provided midway in the intake pipe 15 on the downstream side of the compressor 17.

図２に示される排気浄化装置の場合、運転時にディーゼルエンジン１から排出される排気ガス２は、前段酸化触媒４を通過した後、パティキュレートフィルタ５においてパティキュレートが捕集され、該パティキュレートフィルタ５においてパティキュレートが捕集された排気ガス２は、選択還元型触媒６へ導かれるが、このとき、制御装置１４からの駆動指令信号１１ａと開弁指令信号１３ａとによって供給ポンプ１１とインジェクタ１３とを作動させることにより、必要量の尿素水８を噴射ノズル１２から前記排気ガス２中へ噴射させると、該噴射された尿素水８が排気ガス２中で
（ＮＨ2）2・ＣＯ＋Ｈ2Ｏ→２ＮＨ3＋ＣＯ2
で示される化学反応式によりアンモニアと炭酸ガスに熱分解され、これにより生じたアンモニアが選択還元型触媒６上で排気ガス２中のＮＯxと反応し、該排気ガス２中のＮＯxが還元浄化されることになる。 In the case of the exhaust gas purification apparatus shown in FIG. 2, the exhaust gas 2 discharged from the diesel engine 1 during operation passes through the pre-stage oxidation catalyst 4, and then particulates are collected in the particulate filter 5, and the particulate filter The exhaust gas 2 in which the particulates are collected in 5 is guided to the selective catalytic reduction catalyst 6. At this time, the supply pump 11 and the injector 13 are driven by the drive command signal 11 a and the valve opening command signal 13 a from the control device 14. When the required amount of urea water 8 is injected from the injection nozzle 12 into the exhaust gas 2, the injected urea water 8 becomes (NH 2 ) 2 · CO + H 2 O in the exhaust gas 2. → 2NH 3 + CO 2
Is decomposed into ammonia and carbon dioxide by the chemical reaction formula shown below, and the resulting ammonia reacts with NOx in the exhaust gas 2 on the selective catalytic reduction catalyst 6, and the NOx in the exhaust gas 2 is reduced and purified. Will be.

一方、前記パティキュレートフィルタ５の再生時には、例えば、通常の圧縮行程後期の噴射に加え排気行程での燃料噴射を行って、該燃料を前段酸化触媒４で燃焼させることにより排気温度を上昇させ、これにより、パティキュレートフィルタ５に捕集されたパティキュレートの酸化反応を促進して燃焼除去することが行われる。   On the other hand, when the particulate filter 5 is regenerated, for example, fuel injection is performed in the exhaust stroke in addition to normal injection in the latter half of the compression stroke, and the exhaust temperature is increased by burning the fuel in the pre-stage oxidation catalyst 4; As a result, the oxidation reaction of the particulates collected by the particulate filter 5 is promoted and removed by combustion.

図３は従来における排気浄化装置の他の例を示す概略図であって、図中、図２と同一の符号を付した部分は同一物を表わしており、パティキュレートフィルタ５を選択還元型触媒６より下流側に配置したものであり、排気ガス２中のＮＯxが還元浄化された後にパティキュレートの捕集が行われる点を除いて、基本的な作用については、図２に示される排気浄化装置の場合と同様である。   FIG. 3 is a schematic view showing another example of a conventional exhaust gas purification apparatus. In the figure, the same reference numerals as those in FIG. 2 denote the same parts, and the particulate filter 5 is replaced with a selective reduction catalyst. Except for the point that particulates are collected after NOx in the exhaust gas 2 is reduced and purified, the basic action is shown in FIG. The same as in the case of the apparatus.

尚、図２、図３の排気浄化装置と関連する一般的技術水準を示すものとしては、例えば、特許文献１がある。
特開平９−１３７７１６号公報 For example, Patent Document 1 shows a general technical level related to the exhaust gas purification apparatus of FIGS.
JP-A-9-137716

ところで、図２に示されるような排気浄化装置の場合、排気ガス２の熱がＮＯx低減触媒としての選択還元型触媒６より上流側に配置されたパティキュレートフィルタ５に奪われやすくなると共に、排気ガス２が選択還元型触媒６に到達するまでに長い管路を通過することに伴って放熱が大きくなり、選択還元型触媒６での温度が低くなるため、ＮＯx低減率を充分に上げることができなくなるという欠点を有していた。   By the way, in the case of the exhaust gas purification apparatus as shown in FIG. 2, the heat of the exhaust gas 2 is easily taken away by the particulate filter 5 arranged on the upstream side of the selective reduction catalyst 6 as the NOx reduction catalyst, and the exhaust gas is exhausted. As the gas 2 passes through the long pipeline until it reaches the selective catalytic reduction catalyst 6, the heat radiation increases, and the temperature at the selective catalytic reduction catalyst 6 decreases, so that the NOx reduction rate can be sufficiently increased. It had the disadvantage that it could not be done.

又、図３に示されるような排気浄化装置の場合、パティキュレートフィルタ５の再生を行うときに、該パティキュレートフィルタ５より上流側に配置された選択還元型触媒６によって熱が奪われるため、再生に時間がかかり、燃費の悪化につながる一方、選択還元型触媒６を通過する排気温度がかなり高温となることから選択還元型触媒６が熱劣化するという不具合があった。   Further, in the case of an exhaust purification device as shown in FIG. 3, when the particulate filter 5 is regenerated, heat is taken away by the selective reduction catalyst 6 disposed on the upstream side of the particulate filter 5. While regeneration takes time and leads to deterioration of fuel consumption, the exhaust temperature passing through the selective catalytic reduction catalyst 6 becomes considerably high, so that the selective catalytic reduction catalyst 6 is thermally deteriorated.

本発明は、斯かる実情に鑑み、ＮＯx低減触媒での温度低下を抑えてＮＯx低減率の向上を図ることができ、且つパティキュレートフィルタの再生時における燃費悪化の抑制並びにＮＯx低減触媒の熱劣化防止を図り得る排気浄化装置を提供しようとするものである。   In view of such circumstances, the present invention can improve the NOx reduction rate by suppressing the temperature drop in the NOx reduction catalyst, suppress the deterioration of fuel consumption during regeneration of the particulate filter, and thermally deteriorate the NOx reduction catalyst. It is an object of the present invention to provide an exhaust purification device that can be prevented.

本発明は、エンジンから排出される排気ガスが流通する排気管の途中に設けられたＮＯx低減触媒と、
該ＮＯx低減触媒より下流側における排気管の途中に設けられたパティキュレートフィルタと、
前記エンジンから排出される排気ガスを前記ＮＯx低減触媒、パティキュレートフィルタの順に通過させる通常運転位置と、前記エンジンから排出される排気ガスを前記ＮＯx低減触媒を通過させずに直接パティキュレートフィルタへ導くフィルタ再生位置とに切り換え可能な切換バルブと、
通常運転時には前記切換バルブを通常運転位置に切り換え、パティキュレートフィルタの再生時には前記切換バルブをフィルタ再生位置に切り換える制御装置と
を備えたことを特徴とする排気浄化装置にかかるものである。 The present invention is a NOx reduction catalyst provided in the middle of an exhaust pipe through which exhaust gas discharged from an engine flows,
A particulate filter provided in the middle of the exhaust pipe downstream from the NOx reduction catalyst;
A normal operation position where exhaust gas discharged from the engine passes through the NOx reduction catalyst and the particulate filter in this order, and exhaust gas discharged from the engine is directly guided to the particulate filter without passing through the NOx reduction catalyst. A switching valve that can be switched to a filter regeneration position;
And a control device that switches the switching valve to the normal operating position during normal operation and switches the switching valve to the filter regeneration position when regenerating the particulate filter.

上記手段によれば、以下のような作用が得られる。   According to the above means, the following operation can be obtained.

通常運転時には、制御装置により切換バルブが通常運転位置に切り換えられており、エンジンから排出される排気ガスは、ＮＯx低減触媒、パティキュレートフィルタの順に通過するため、排気ガスの熱がパティキュレートフィルタに奪われることがなくなると共に、排気ガスがＮＯx低減触媒に到達するまでに長い管路を通過せず放熱が小さく、ＮＯx低減触媒での温度が高くなるため、ＮＯx低減率を充分に上げることが可能となる。   During normal operation, the switching valve is switched to the normal operation position by the control device, and the exhaust gas exhausted from the engine passes through the NOx reduction catalyst and the particulate filter in this order, so the heat of the exhaust gas passes through the particulate filter. The exhaust gas does not pass through the long pipeline until it reaches the NOx reduction catalyst, and the heat release is small and the temperature at the NOx reduction catalyst becomes high, so the NOx reduction rate can be increased sufficiently. It becomes.

又、パティキュレートフィルタの再生時には、制御装置により切換バルブがフィルタ再生位置に切り換えられ、エンジンから排出される排気ガスは前記ＮＯx低減触媒を通過せずに直接パティキュレートフィルタへ導かれるため、該パティキュレートフィルタより上流側に配置されたＮＯx低減触媒によって熱が奪われることがなくなり、再生が迅速に行われ、燃費の悪化が避けられると共に、高温の排気ガスがＮＯx低減触媒を通過しないことからＮＯx低減触媒が熱劣化する心配もない。   In addition, when the particulate filter is regenerated, the control valve switches the switching valve to the filter regeneration position, and exhaust gas discharged from the engine is directly guided to the particulate filter without passing through the NOx reduction catalyst. Heat is not taken away by the NOx reduction catalyst arranged upstream of the curate filter, regeneration is performed quickly, deterioration of fuel consumption is avoided, and high-temperature exhaust gas does not pass through the NOx reduction catalyst. There is no concern that the reduced catalyst will be thermally degraded.

前記排気浄化装置においては、切換バルブより上流側における排気管の途中に、酸化触媒を配設することができる。   In the exhaust emission control device, an oxidation catalyst can be disposed in the middle of the exhaust pipe upstream of the switching valve.

本発明の排気浄化装置によれば、ＮＯx低減触媒での温度低下を抑えてＮＯx低減率の向上を図ることができ、且つパティキュレートフィルタの再生時における燃費悪化の抑制並びにＮＯx低減触媒の熱劣化防止を図り得るという優れた効果を奏し得る。   According to the exhaust purification apparatus of the present invention, it is possible to improve the NOx reduction rate by suppressing the temperature drop in the NOx reduction catalyst, and to suppress the deterioration of fuel consumption during regeneration of the particulate filter and the thermal deterioration of the NOx reduction catalyst. An excellent effect that the prevention can be achieved can be achieved.

以下、本発明の実施の形態を添付図面を参照して説明する。   Embodiments of the present invention will be described below with reference to the accompanying drawings.

図１（ａ），（ｂ）は本発明を実施する形態の一例であって、図中、図２及び図３と同一の符号を付した部分は同一物を表わしており、基本的な構成は図２及び図３に示す従来のものと同様であるが、本図示例の特徴とするところは、図１（ａ），（ｂ）に示す如く、ディーゼルエンジン１から排出される排気ガス２が流通する排気管３の前段酸化触媒４より下流側に、ＮＯx低減触媒としての選択還元型触媒６とパティキュレートフィルタ５とを設け、前記選択還元型触媒６の入側における排気管３に対して、該選択還元型触媒６の出側（パティキュレートフィルタ５の入側）における排気管３を近づけるように湾曲させ、該湾曲させて近づけた排気管３の部分に、ディーゼルエンジン１から排出される排気ガス２を選択還元型触媒６、パティキュレートフィルタ５の順に通過させる通常運転位置Ａと、前記ディーゼルエンジン１から排出される排気ガス２を前記選択還元型触媒６を通過させずに直接パティキュレートフィルタ５へ導くフィルタ再生位置Ｂとに切り換え可能な切換バルブ２０を配設し、通常運転時には前記切換バルブ２０を通常運転位置Ａに切り換え、パティキュレートフィルタ５の再生時には前記切換バルブ２０をフィルタ再生位置Ｂに切り換えるための制御信号２０ａを制御装置１４から出力するよう構成した点にある。   1 (a) and 1 (b) are examples of embodiments for carrying out the present invention. In the figure, the parts denoted by the same reference numerals as those in FIGS. Is the same as the conventional one shown in FIGS. 2 and 3, but the feature of the illustrated example is that the exhaust gas 2 discharged from the diesel engine 1 as shown in FIGS. 1 (a) and 1 (b). A selective reduction catalyst 6 and a particulate filter 5 as a NOx reduction catalyst are provided downstream of the upstream oxidation catalyst 4 of the exhaust pipe 3 through which the exhaust gas flows, and the exhaust pipe 3 on the inlet side of the selective reduction catalyst 6 is provided. Then, the exhaust pipe 3 on the outlet side of the selective catalytic reduction catalyst 6 (the inlet side of the particulate filter 5) is bent so as to approach, and the exhaust pipe 3 that is bent and approached is discharged from the diesel engine 1. Exhaust gas 2 is selectively reduced catalyst 6, putty A normal operation position A through which the particulate filter 5 is passed in order, and a filter regeneration position B in which the exhaust gas 2 exhausted from the diesel engine 1 is guided directly to the particulate filter 5 without passing through the selective reduction catalyst 6. A switchable switch valve 20 is provided, and the control valve 20 is switched to the normal operation position A during normal operation, and a control signal 20a for switching the switch valve 20 to the filter regeneration position B during regeneration of the particulate filter 5. It is the point which comprised so that it might output from the control apparatus 14.

尚、本図示例の場合、パティキュレートフィルタ５の入側に前段酸化触媒４とは別に酸化触媒２１を設けるようにしてある。   In the illustrated example, an oxidation catalyst 21 is provided on the inlet side of the particulate filter 5 separately from the pre-stage oxidation catalyst 4.

次に、上記図示例の作用を説明する。   Next, the operation of the illustrated example will be described.

通常運転時には、図１（ａ）に示す如く、制御装置１４から出力される制御信号２０ａにより、切換バルブ２０が通常運転位置Ａに切り換えられており、ディーゼルエンジン１から排出される排気ガス２は、選択還元型触媒６、パティキュレートフィルタ５の順に通過するため、排気ガス２の熱がパティキュレートフィルタ５に奪われることがなくなると共に、排気ガス２が選択還元型触媒６に到達するまでに長い管路を通過せず放熱が小さく、選択還元型触媒６での温度が高くなるため、ＮＯx低減率を充分に上げることが可能となる。   During normal operation, as shown in FIG. 1A, the switching valve 20 is switched to the normal operation position A by the control signal 20a output from the control device 14, and the exhaust gas 2 discharged from the diesel engine 1 is Since the selective reduction catalyst 6 and the particulate filter 5 pass in this order, the heat of the exhaust gas 2 is not deprived by the particulate filter 5 and is long until the exhaust gas 2 reaches the selective reduction catalyst 6. Since it does not pass through the pipeline and the heat radiation is small and the temperature at the selective catalytic reduction catalyst 6 becomes high, the NOx reduction rate can be sufficiently increased.

又、パティキュレートフィルタ５の再生時には、図１（ｂ）に示す如く、制御装置１４から出力される制御信号２０ａにより、切換バルブ２０がフィルタ再生位置Ｂに切り換えられ、ディーゼルエンジン１から排出される排気ガス２は前記選択還元型触媒６を通過せずに酸化触媒２１を介して直接パティキュレートフィルタ５へ導かれるため、該パティキュレートフィルタ５より上流側に配置された選択還元型触媒６によって熱が奪われることがなくなり、再生が迅速に行われ、燃費の悪化が避けられると共に、高温の排気ガス２が選択還元型触媒６を通過しないことから選択還元型触媒６が熱劣化する心配もない。   When the particulate filter 5 is regenerated, the switching valve 20 is switched to the filter regeneration position B by the control signal 20a output from the control device 14 as shown in FIG. Since the exhaust gas 2 is directly guided to the particulate filter 5 through the oxidation catalyst 21 without passing through the selective catalytic reduction catalyst 6, the exhaust gas 2 is heated by the selective catalytic reduction catalyst 6 disposed on the upstream side of the particulate filter 5. Is not deprived, the regeneration is performed quickly, the deterioration of the fuel consumption is avoided, and the high temperature exhaust gas 2 does not pass through the selective catalytic reduction catalyst 6, so that there is no fear that the selective catalytic reduction catalyst 6 is thermally deteriorated. .

こうして、ＮＯx低減触媒としての選択還元型触媒６での温度低下を抑えてＮＯx低減率の向上を図ることができ、且つパティキュレートフィルタ５の再生時における燃費悪化の抑制並びにＮＯx低減触媒としての選択還元型触媒６の熱劣化防止を図り得る。   Thus, the temperature reduction in the selective reduction catalyst 6 as the NOx reduction catalyst can be suppressed and the NOx reduction rate can be improved, and the deterioration of the fuel consumption during the regeneration of the particulate filter 5 can be suppressed and the selection as the NOx reduction catalyst can be performed. It is possible to prevent thermal degradation of the reduced catalyst 6.

尚、本発明の排気浄化装置は、上述の図示例にのみ限定されるものではなく、ＮＯx低減触媒として選択還元型触媒の代わりにＮＯx吸蔵還元触媒を用いたものにも適用可能なこと等、その他、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。   The exhaust emission control device of the present invention is not limited to the above illustrated example, and can be applied to a NOx reduction catalyst using a NOx occlusion reduction catalyst instead of a selective reduction catalyst, etc. In addition, it goes without saying that various changes can be made without departing from the scope of the present invention.

本発明を実施する形態の一例を示す概略図であって、（ａ）は通常運転時における切換バルブの状態を示す図、（ｂ）はパティキュレートフィルタ再生時における切換バルブの状態を示す図である。BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of embodiment which implements this invention, Comprising: (a) is a figure which shows the state of the switching valve at the time of normal operation, (b) is a figure which shows the state of the switching valve at the time of particulate filter regeneration. is there. 従来における排気浄化装置の一例を示す概略図である。It is the schematic which shows an example of the conventional exhaust gas purification apparatus. 従来における排気浄化装置の他の例を示す概略図である。It is the schematic which shows the other example of the conventional exhaust gas purification apparatus.

符号の説明Explanation of symbols

１ ディーゼルエンジン（エンジン）
２ 排気ガス
３ 排気管
４ 前段酸化触媒（酸化触媒）
５ パティキュレートフィルタ
６ 選択還元型触媒（ＮＯx低減触媒）
１４ 制御装置
２０ 切換バルブ
２０ａ 制御信号
Ａ 通常運転位置
Ｂ フィルタ再生位置 1 Diesel engine (engine)
2 Exhaust gas 3 Exhaust pipe 4 Pre-stage oxidation catalyst (oxidation catalyst)
5 Particulate filter 6 Selective reduction catalyst (NOx reduction catalyst)
14 Control device 20 Switching valve 20a Control signal A Normal operation position B Filter regeneration position

Claims (2)

エンジンから排出される排気ガスが流通する排気管の途中に設けられたＮＯx低減触媒と、
該ＮＯx低減触媒より下流側における排気管の途中に設けられたパティキュレートフィルタと、
前記エンジンから排出される排気ガスを前記ＮＯx低減触媒、パティキュレートフィルタの順に通過させる通常運転位置と、前記エンジンから排出される排気ガスを前記ＮＯx低減触媒を通過させずに直接パティキュレートフィルタへ導くフィルタ再生位置とに切り換え可能な切換バルブと、
通常運転時には前記切換バルブを通常運転位置に切り換え、パティキュレートフィルタの再生時には前記切換バルブをフィルタ再生位置に切り換える制御装置と
を備えたことを特徴とする排気浄化装置。 A NOx reduction catalyst provided in the middle of an exhaust pipe through which exhaust gas discharged from the engine flows;
A particulate filter provided in the middle of the exhaust pipe downstream from the NOx reduction catalyst;
A normal operation position where exhaust gas discharged from the engine passes through the NOx reduction catalyst and the particulate filter in this order, and exhaust gas discharged from the engine is directly guided to the particulate filter without passing through the NOx reduction catalyst. A switching valve that can be switched to a filter regeneration position;
An exhaust emission control device comprising: a control device that switches the switching valve to a normal operation position during normal operation and switches the switching valve to a filter regeneration position during regeneration of the particulate filter. 切換バルブより上流側における排気管の途中に、酸化触媒を配設した請求項１記載の排気浄化装置。   The exhaust emission control device according to claim 1, wherein an oxidation catalyst is disposed in the middle of the exhaust pipe upstream of the switching valve.
JP2006025795A 2006-02-02 2006-02-02 Exhaust emission control device Pending JP2007205267A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008196328A (en) * 2007-02-09 2008-08-28 Hino Motors Ltd Exhaust emission control device
JP2009036109A (en) * 2007-08-02 2009-02-19 Hino Motors Ltd Exhaust emission control device
WO2011148818A1 (en) * 2010-05-28 2011-12-01 いすゞ自動車株式会社 Exhaust gas purification device for internal combustion engine
JP2015140790A (en) * 2014-01-30 2015-08-03 マツダ株式会社 Engine exhaust emission control system
EP2529091B1 (en) 2010-01-25 2016-04-06 Peugeot Citroën Automobiles SA Exhaust gas aftertreatment device of an internal combustion engine
EP2202390B2 (en) † 2007-10-26 2016-05-18 Hino Motors, Ltd. Exhaust emission control device

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008196328A (en) * 2007-02-09 2008-08-28 Hino Motors Ltd Exhaust emission control device
JP2009036109A (en) * 2007-08-02 2009-02-19 Hino Motors Ltd Exhaust emission control device
EP2202390B2 (en) † 2007-10-26 2016-05-18 Hino Motors, Ltd. Exhaust emission control device
EP2529091B1 (en) 2010-01-25 2016-04-06 Peugeot Citroën Automobiles SA Exhaust gas aftertreatment device of an internal combustion engine
WO2011148818A1 (en) * 2010-05-28 2011-12-01 いすゞ自動車株式会社 Exhaust gas purification device for internal combustion engine
JP2011247213A (en) * 2010-05-28 2011-12-08 Isuzu Motors Ltd Exhaust gas purification device for internal combustion engine
JP2015140790A (en) * 2014-01-30 2015-08-03 マツダ株式会社 Engine exhaust emission control system

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