JP2006037769A - Control method for exhaust emission control device - Google Patents

Control method for exhaust emission control device Download PDF

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JP2006037769A
JP2006037769A JP2004215765A JP2004215765A JP2006037769A JP 2006037769 A JP2006037769 A JP 2006037769A JP 2004215765 A JP2004215765 A JP 2004215765A JP 2004215765 A JP2004215765 A JP 2004215765A JP 2006037769 A JP2006037769 A JP 2006037769A
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exhaust
exhaust gas
temperature
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nox
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Ichiro Tsumagari
一郎 津曲
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Hino Motors Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F02M26/33—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage controlling the temperature of the recirculated gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/04—Cooling of air intake supply
    • F02B29/0406—Layout of the intake air cooling or coolant circuit
    • F02B29/0425—Air cooled heat exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/08—Exhaust gas treatment apparatus parameters
    • F02D2200/0802—Temperature of the exhaust gas treatment apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/36—Control for minimising NOx emissions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F02M26/23—Layout, e.g. schematics
    • F02M26/27—Layout, e.g. schematics with air-cooled heat exchangers
    • 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)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To surely perform reduction treatment of NOx. <P>SOLUTION: When a temperature of a NOx reduction catalyst 14 is below a predetermined temperature range, a recirculation amount of exhaust gas G fed to an intake passage 6 is increased to reduce NOx content in the exhaust gas G exhausted from a diesel engine 1. When the temperature of the NOx reduction catalyst 14 is above the predetermined temperature range, the recirculation amount of the exhaust gas G fed to the intake passage 6 is decreased to reduce particulate matter content in the exhaust gas G exhausted from the diesel engine 1. When a low engine load is estimated, fuel injection is corrected to increase an exhaust temperature and thereby to maintain the optimum temperature of the NOx reduction catalyst. On the other hand, when a high engine load is estimated, the fuel injection is corrected to decrease the exhaust temperature and thereby to reduce the particulate matter content in the exhaust gas G. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は排気浄化装置の制御方法に関するものである。   The present invention relates to a method for controlling an exhaust emission control device.

酸素共存状態であっても選択的に窒素酸化物（ＮＯｘ）が還元剤と反応可能な選択還元触媒（ＮＯｘ還元触媒）を車両用ディーゼルエンジンの排気経路に組み込み、アンモニアよりも取り扱いが容易な尿素水を還元剤に用いてＮＯｘ排出濃度の低減を図るようにした排気浄化装置が提案されている（例えば、特許文献１、２参照）。   Urea that is easier to handle than ammonia by incorporating a selective reduction catalyst (NOx reduction catalyst) in which nitrogen oxide (NOx) can selectively react with a reducing agent even in the presence of oxygen in the exhaust path of a diesel engine for vehicles There has been proposed an exhaust emission control device that uses water as a reducing agent to reduce the NOx emission concentration (see, for example, Patent Documents 1 and 2).

このような排気浄化装置は、ＮＯｘ還元触媒の上流側へ尿素水を添加するためのノズル（還元剤添加手段）を備え、触媒温度が約２００℃を上回る状態で尿素水を添加すると、当該尿素水がアンモニアと二酸化炭素に分解し、次いで、ＮＯｘ還元触媒とアンモニアにより排気に含まれているＮＯｘが還元処理される。   Such an exhaust purification device includes a nozzle (reducing agent adding means) for adding urea water to the upstream side of the NOx reduction catalyst, and when urea water is added in a state where the catalyst temperature exceeds about 200 ° C., Water is decomposed into ammonia and carbon dioxide, and then NOx contained in the exhaust is reduced by the NOx reduction catalyst and ammonia.

また、排気再循環（ＥＧＲ:Exhaust Gas Recirculation）を適用した過給機付内燃機関では、エンジン排気経路から分流した排気を、ＥＧＲクーラ（水冷方式の管形熱交換器）が組み込んであるＥＧＲ管路によりエンジン吸気経路へ送給し、燃焼温度の低下を図ってＮＯｘの発生を低減させている。
特開２００２−１６１７３２号公報 特表２００２−５１３１１０号公報 In an internal combustion engine with a supercharger to which exhaust gas recirculation (EGR) is applied, an EGR pipe in which an EGR cooler (water-cooled tubular heat exchanger) is incorporated into the exhaust gas diverted from the engine exhaust path. The fuel is fed to the engine intake path by the road, and the generation of NOx is reduced by lowering the combustion temperature.
JP 2002-161732 A JP-T-2002-513110

上記の排気浄化装置では、市街地走行などによって排気温度が低くなると、還元触媒が活性温度に達しないためにＮＯｘの還元処理が不充分になることが想定される。   In the above exhaust purification apparatus, it is assumed that when the exhaust temperature is lowered due to traveling in an urban area or the like, the reduction catalyst does not reach the activation temperature, so that the NOx reduction treatment becomes insufficient.

本発明は上述した実情に鑑みてなしたもので、ＮＯｘの還元処理が確実にできるようにすることを目的としている。   The present invention has been made in view of the above-described circumstances, and an object thereof is to ensure that NOx reduction treatment can be performed reliably.

上記目的を達成するために、本発明は、エンジン排気経路に組み込んであるＮＯｘ還元触媒の上流側へ還元剤を添加し、排気中のＮＯｘの還元浄化を図る排気浄化装置の制御方法であって、触媒温度が所定の温度域を下回った際に、エンジン吸気経路へ送給する排気の再循環量を増加させ、触媒温度が所定の温度域を上回った際に、エンジン吸気経路へ送給する排気の再循環量を減少させ、これに加えて、エンジン負荷が高くなるときに、排気温度が下がるように燃料噴射を行ない、エンジン負荷が低くなるときに、排気温度が上がるように燃料噴射を行なう。   In order to achieve the above object, the present invention provides a control method for an exhaust gas purification apparatus for reducing and purifying NOx in exhaust gas by adding a reducing agent upstream of a NOx reduction catalyst incorporated in an engine exhaust path. When the catalyst temperature falls below a predetermined temperature range, the amount of exhaust gas recirculated to the engine intake path is increased, and when the catalyst temperature exceeds the predetermined temperature range, the exhaust gas is sent to the engine intake path. In addition to reducing the amount of exhaust recirculation, fuel injection is performed so that the exhaust temperature decreases when the engine load increases, and fuel injection is performed so that the exhaust temperature increases when the engine load decreases. Do.

更に、触媒温度が所定の温度域に達し且つエンジン負荷が低くなるときに、エンジン吸気経路へ送給する排気の再循環量を増加させ、排気温度が高くなるように燃料噴射を行なう。   Further, when the catalyst temperature reaches a predetermined temperature range and the engine load becomes low, the amount of exhaust gas recirculated to the engine intake path is increased, and fuel injection is performed so that the exhaust gas temperature increases.

本発明においては、触媒温度が低く、ＮＯｘの還元処理に適していない場合は、排気の再循環量を増加させてエンジンが送出する排気のＮＯｘ含有量を減らす。   In the present invention, when the catalyst temperature is low and not suitable for the NOx reduction treatment, the exhaust gas recirculation amount is increased to reduce the NOx content of the exhaust gas delivered by the engine.

触媒温度が高い場合は、触媒によりＮＯｘを還元処理するとともに、排気の再循環量を減少させてエンジンが送出する排気の粒子状物質含有量を減らす。   When the catalyst temperature is high, NOx is reduced by the catalyst, and the exhaust gas recirculation amount is reduced to reduce the particulate matter content of the exhaust gas sent out by the engine.

エンジン負荷が低くなることが見込まれるときは、燃料噴射を補正して排気温度を上げ、触媒がＮＯｘの還元処理に適した温度に保たれるようにする。   When the engine load is expected to decrease, the fuel injection is corrected to raise the exhaust temperature so that the catalyst is maintained at a temperature suitable for the NOx reduction process.

エンジン負荷が高くなることが見込まれるときは、燃料噴射を補正して排気温度を下げ、エンジンが送出する排気の粒子状物質含有量を減らす。   When the engine load is expected to increase, the fuel injection is corrected to lower the exhaust temperature, and the particulate matter content of the exhaust delivered by the engine is reduced.

触媒温度が所定の温度域に達し且つエンジン負荷が低くなることが見込まれるときは、排気の再循環量を増加させてエンジンが送出する排気のＮＯｘ含有量を減らし、燃料噴射を補正して排気温度を上げ、触媒がＮＯｘの還元処理に適した温度に保たれるようにする。   When the catalyst temperature reaches a predetermined temperature range and the engine load is expected to decrease, the exhaust gas recirculation amount is increased to reduce the NOx content of the exhaust gas sent by the engine, and the fuel injection is corrected to exhaust the exhaust gas. The temperature is raised so that the catalyst is maintained at a temperature suitable for NOx reduction treatment.

本発明の排気浄化装置の制御方法によれば、下記のような優れた効果を奏し得る。   According to the control method of the exhaust emission control device of the present invention, the following excellent effects can be obtained.

（１）触媒温度が低い場合は、排気の再循環量を増加させてエンジンが送出する排気のＮＯｘ含有量を減らすので、市街地走行時にもＮＯｘの放出を抑制することができる。   (1) When the catalyst temperature is low, the NOx content of the exhaust gas sent out by the engine is increased by increasing the exhaust gas recirculation amount, so that NOx emission can be suppressed even when traveling in urban areas.

（２）触媒温度が高く、触媒によるＮＯｘの還元処理が可能な場合は、排気の再循環量を減少させるので、排気の粒子状物質含有量を減らすことができ、燃費の向上も図れる。   (2) When the catalyst temperature is high and the reduction treatment of NOx by the catalyst is possible, the exhaust gas recirculation amount is reduced, so that the particulate matter content of the exhaust gas can be reduced and the fuel consumption can be improved.

（３）エンジン負荷が低くなることが見込まれる場合には、燃料噴射の補正により排気温度を上げて触媒をＮＯｘの還元処理に適した温度に保ち、エンジン負荷が高くなることが見込まれる場合には、燃料噴射の補正により排気温度を下げてエンジンが送出する排気の粒子状物質含有量を減らすので、エンジンが過渡状態であっても排気の浄化を時間遅れなく達成することができる。   (3) When the engine load is expected to be low, the exhaust temperature is raised by correcting the fuel injection to maintain the catalyst at a temperature suitable for NOx reduction treatment, and the engine load is expected to be high. Since the exhaust gas temperature is lowered by correcting the fuel injection and the particulate matter content of the exhaust gas sent out by the engine is reduced, the purification of the exhaust gas can be achieved without a time delay even when the engine is in a transient state.

以下、本発明の実施の形態を図面に基づき説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図１乃至図３は本発明の実施の形態の一例を示すものであり、ディーゼルエンジン１の排気Ｇをタービン２の作動流体にしてコンプレッサ３を駆動するターボチャージャ４と、エアクリーナ５を通過してコンプレッサ３により圧縮された吸気Ａをディーゼルエンジン１へ送給する吸気経路６と、当該ディーゼルエンジン１の排気経路７のタービン２よりも上流側（排気マニホールド）から吸気経路６のコンプレッサ３よりも下流側へ至るＥＧＲ管路８と、制御ユニット（ＥＣＵ：Electronic Control Unit）９とを有している。   FIG. 1 to FIG. 3 show an example of an embodiment of the present invention. The turbocharger 4 that drives the compressor 3 using the exhaust G of the diesel engine 1 as the working fluid of the turbine 2 and the air cleaner 5 pass through. An intake path 6 for supplying the intake air A compressed by the compressor 3 to the diesel engine 1, and an upstream side (exhaust manifold) of the exhaust path 7 of the diesel engine 1 from the upstream side (exhaust manifold) of the intake path 6 and downstream of the compressor 3. It has an EGR pipe line 8 extending to the side and a control unit (ECU: Electronic Control Unit) 9.

タービン２のノズルベーンの開度は、アクチュエータ（図示せず）によって調整でき、例えば、一定の排気Ｇの流入量に対してノズルベーンの開度を拡げた場合には、排気Ｇの流速が下がってタービン２の回転数が低くなり、コンプレッサ３の吸気Ａの吸い込み量が減る。   The opening degree of the nozzle vane of the turbine 2 can be adjusted by an actuator (not shown). For example, when the opening degree of the nozzle vane is increased with respect to a constant inflow amount of the exhaust gas G, the flow velocity of the exhaust gas G decreases and the turbine The rotational speed of 2 is reduced, and the intake amount of the intake air A of the compressor 3 is reduced.

また、一定の排気Ｇの流入量に対してノズルベーンの開度を狭めた場合には、排気Ｇの流速が上がってタービン２の回転数が高くなり、コンプレッサ３の吸気Ａの吸い込み量が増す。   Further, when the opening degree of the nozzle vane is narrowed with respect to a constant exhaust gas inflow amount, the flow rate of the exhaust gas G increases, the rotational speed of the turbine 2 increases, and the intake amount of the intake air A of the compressor 3 increases.

吸気経路６には、コンプレッサ３が圧縮した吸気Ａを冷却するためのインタクーラ１０が組み込んであり、エアクリーナ５とコンプレッサ３の吸気導入口との間には、吸気Ａの流量を調整するための吸気絞り弁１１が組み込んである。   The intake passage 6 incorporates an intercooler 10 for cooling the intake air A compressed by the compressor 3, and an intake air for adjusting the flow rate of the intake air A between the air cleaner 5 and the intake air inlet of the compressor 3. A throttle valve 11 is incorporated.

排気経路７には、排気Ｇの流量を調整するための排気絞り弁１２、排気Ｇに尿素水Ｕを噴霧する添加ノズル１３、及びＮＯｘ還元触媒１４が直列に組み込んであり、当該ＮＯｘ還元触媒１４の入口側と出口側には、温度センサ１５，１６が設けてある。   An exhaust throttle valve 12 for adjusting the flow rate of the exhaust G, an addition nozzle 13 for spraying urea water U to the exhaust G, and a NOx reduction catalyst 14 are incorporated in the exhaust path 7 in series. Temperature sensors 15 and 16 are provided on the inlet side and the outlet side.

また、添加ノズル１３には、タンク１７に貯留してある尿素水Ｕを吸引送出するポンプ１８が、電磁弁１９を介して接続されている。   In addition, a pump 18 that sucks and delivers urea water U stored in the tank 17 is connected to the addition nozzle 13 via an electromagnetic valve 19.

更に、ＥＧＲ管路８には、排気Ｇを冷却するためのＥＧＲクーラ２０と排気Ｇの流量を調整するためのＥＧＲバルブ２１が直列に組み込んであり、当該ＥＧＲバルブ２１、前記吸気絞り弁１１、及び排気絞り弁１２は、いずれもアクチュエータ（図示せず）によって開度調整ができるように構成してある。   Further, an EGR cooler 20 for cooling the exhaust G and an EGR valve 21 for adjusting the flow rate of the exhaust G are incorporated in series in the EGR pipe line 8, and the EGR valve 21, the intake throttle valve 11, The exhaust throttle valve 12 is configured so that the opening degree can be adjusted by an actuator (not shown).

ディーゼルエンジン１が稼動状態であるとき、排気Ｇの大部分はタービン２へ流入してコンプレッサ３を駆動した後、ＮＯｘ還元触媒１４を経て大気中に放出される。   When the diesel engine 1 is in an operating state, most of the exhaust G flows into the turbine 2 and drives the compressor 3, and then is released into the atmosphere via the NOx reduction catalyst 14.

エアクリーナ５からコンプレッサ３に流入して圧縮された吸気Ａは、インタクーラ１０を通ってディーゼルエンジン１へ送給され、これと同時に排気Ｇの一部がＥＧＲ管路８へ流入し、ＥＧＲクーラ２０により冷却され且つＥＧＲバルブ２１で流量調整が行なわれた排気Ｇがディーゼルエンジン１へ送給される。   The compressed intake air A flowing into the compressor 3 from the air cleaner 5 is supplied to the diesel engine 1 through the intercooler 10, and at the same time, a part of the exhaust G flows into the EGR pipe 8, and the EGR cooler 20 Exhaust gas G that has been cooled and whose flow rate has been adjusted by the EGR valve 21 is supplied to the diesel engine 1.

吸気絞り弁１１、排気絞り弁１２、ＥＧＲバルブ２１の開度は、アクチュエータ（図示せず）によって調整でき、ＥＧＲバルブ２１の開度を拡げた状態とし、吸気絞り弁１１、あるいは排気絞り弁１２の少なくとも一方の開度を狭めると、排気ＧがＥＧＲ管路８からディーゼルエンジン１に送給されやすくなる。   The opening degree of the intake throttle valve 11, the exhaust throttle valve 12, and the EGR valve 21 can be adjusted by an actuator (not shown). The opening degree of the EGR valve 21 is increased, and the intake throttle valve 11 or the exhaust throttle valve 12 is set. When at least one of the opening degrees is narrowed, the exhaust G is easily fed from the EGR pipe 8 to the diesel engine 1.

制御ユニット９は、ＮＯｘの還元処理に適した温度域Ｔに対する現在の触媒温度の状況を見定めるフラグ判定機能Ｔｃと、アクセル開度、エンジン回転数、燃料噴射量などの情報に基づいてエンジン負荷の変動を見定めるフラグ判定機能Ｌｃを具備し、これらの判定結果に応じて排気Ｇの再循環量を調整する操作、並びに排気温度を調整する操作を実行するように構成してある。   The control unit 9 determines the engine load based on the flag determination function Tc for determining the current catalyst temperature with respect to the temperature range T suitable for the NOx reduction process, and information such as the accelerator opening, the engine speed, and the fuel injection amount. A flag determination function Lc for determining variation is provided, and an operation for adjusting the recirculation amount of the exhaust gas G and an operation for adjusting the exhaust gas temperature are executed in accordance with these determination results.

排気Ｇの再循環量の調整操作は、ＥＧＲバルブ２１の開度補正、吸気絞り弁１１と排気絞り弁１２の絞り制御、ターボチャージャ４の吸気増減制御で対処し、また、排気温度の調整操作は、燃料噴射圧の増減補正、並びに噴射時期補正で対処する。   The adjustment operation of the recirculation amount of the exhaust G is dealt with by the opening correction of the EGR valve 21, the throttle control of the intake throttle valve 11 and the exhaust throttle valve 12, the intake air increase / decrease control of the turbocharger 4, and the exhaust temperature adjustment operation Are dealt with by increasing / decreasing the fuel injection pressure and correcting the injection timing.

触媒温度が温度域Ｔを下回っている場合は、ＥＧＲバルブ２１の開度を拡げて排気Ｇの再循環量を増加させ、ディーゼルエンジン１が送出する排気ＧのＮＯｘ含有量を減らしてＮＯｘ還元触媒１４の還元処理能力を補完する。   When the catalyst temperature is lower than the temperature range T, the opening degree of the EGR valve 21 is increased to increase the recirculation amount of the exhaust G, and the NOx content of the exhaust G sent from the diesel engine 1 is reduced to reduce the NOx reduction catalyst. Complements 14 reduction processing capacity.

次いで、エンジン負荷が高くなることが見込まれるときは、燃料噴射圧の増補正と噴射時期補正とにより排気温度を下げ、ディーゼルエンジン１が送出する排気Ｇの粒子状物質含有量を減らし、また、エンジン負荷が低くなることが見込まれるときは、燃料噴射圧の減補正と噴射時期補正とにより排気温度を上げ、ＮＯｘ還元触媒１４がＮＯｘの還元処理に適した温度域Ｔに保たれるようにする。   Next, when the engine load is expected to increase, the exhaust temperature is lowered by increasing the fuel injection pressure and the injection timing, and the particulate matter content of the exhaust G sent out by the diesel engine 1 is reduced. When the engine load is expected to decrease, the exhaust gas temperature is raised by reducing the fuel injection pressure and correcting the injection timing so that the NOx reduction catalyst 14 is maintained in the temperature range T suitable for the NOx reduction process. To do.

更に、吸気絞り弁１１と排気絞り弁１２の絞り制御、及びターボチャージャ４の吸気減制御を実行し、排気ＧがＥＧＲ管路８からディーゼルエンジン１に送給されやすい状態とする。   Further, the throttle control of the intake throttle valve 11 and the exhaust throttle valve 12 and the intake air reduction control of the turbocharger 4 are executed so that the exhaust G is easily fed to the diesel engine 1 from the EGR line 8.

つまり、ＮＯｘ還元触媒１４で低温で且つディーゼルエンジン１が過渡状態であっても排気Ｇの浄化を時間遅れなく達成することができる。   That is, purification of the exhaust gas G can be achieved without a time delay even if the NOx reduction catalyst 14 is at a low temperature and the diesel engine 1 is in a transient state.

触媒温度が温度域Ｔを上回っている場合は、ＮＯｘ還元触媒１４によってＮＯｘの還元処理を行なうとともに、ＥＧＲバルブ２１の開度を狭めて排気Ｇの再循環量を減少させ、ディーゼルエンジン１が送出する排気Ｇの粒子状物質含有量を減らす。   When the catalyst temperature exceeds the temperature range T, the NOx reduction catalyst 14 performs NOx reduction processing, and the opening degree of the EGR valve 21 is narrowed to reduce the recirculation amount of the exhaust G. Reduce the particulate matter content of exhaust G.

次いで、エンジン負荷が高くなることが見込まれるときは、燃料噴射圧の増補正と噴射時期補正とにより排気温度を下げ、ディーゼルエンジン１が送出する排気Ｇの粒子状物質含有量を減らし、また、エンジン負荷が低くなることが見込まれるときは、燃料噴射圧の減補正と噴射時期補正とにより排気温度を上げ、ＮＯｘ還元触媒１４がＮＯｘの還元処理に適した温度域Ｔに保たれるようにする。   Next, when the engine load is expected to increase, the exhaust temperature is lowered by increasing the fuel injection pressure and the injection timing, and the particulate matter content of the exhaust G sent out by the diesel engine 1 is reduced. When the engine load is expected to decrease, the exhaust gas temperature is raised by reducing the fuel injection pressure and correcting the injection timing so that the NOx reduction catalyst 14 is maintained in the temperature range T suitable for the NOx reduction process. To do.

更に、ターボチャージャ４の吸気増制御を実行して、排気温度の過昇温を抑制する。   Further, the intake air increase control of the turbocharger 4 is executed to suppress an excessive increase in the exhaust gas temperature.

つまり、ＮＯｘ還元触媒１４が高温で且つディーゼルエンジン１が過渡状態であっても排気Ｇの浄化を時間遅れなく達成することができる。   That is, even if the NOx reduction catalyst 14 is at a high temperature and the diesel engine 1 is in a transient state, purification of the exhaust gas G can be achieved without a time delay.

触媒温度が温度域Ｔに達し且つエンジン負荷が低くなることが見込まれるときは、前述の触媒温度が温度域Ｔを下回った場合と同様に、ＥＧＲバルブ２１の開度を拡げて排気Ｇの再循環量を増加させ、ディーゼルエンジン１が送出する排気ＧのＮＯｘ含有量を減らす。   When the catalyst temperature reaches the temperature range T and the engine load is expected to decrease, the opening degree of the EGR valve 21 is increased and the exhaust gas G is restarted as in the case where the catalyst temperature falls below the temperature range T. The circulation amount is increased, and the NOx content of the exhaust G sent from the diesel engine 1 is reduced.

次いで、燃料噴射圧の減補正と噴射時期補正とにより排気温度を上げ、ＮＯｘ還元触媒１４がＮＯｘの還元処理に適した温度域Ｔに保たれるようにする。   Next, the exhaust gas temperature is raised by the fuel injection pressure reduction correction and the injection timing correction so that the NOx reduction catalyst 14 is maintained in the temperature range T suitable for the NOx reduction process.

更に、吸気絞り弁１１と排気絞り弁１２の絞り制御、及びターボチャージャ４の吸気減制御を実行し、排気ＧがＥＧＲ管路８からディーゼルエンジン１に送給されやすい状態とする。   Further, the throttle control of the intake throttle valve 11 and the exhaust throttle valve 12 and the intake air reduction control of the turbocharger 4 are executed so that the exhaust G is easily fed to the diesel engine 1 from the EGR line 8.

つまり、ＮＯｘ還元触媒１４が適温で且つディーゼルエンジン１が過渡状態であっても排気Ｇの浄化を時間遅れなく達成することができる。   That is, even if the NOx reduction catalyst 14 is at an appropriate temperature and the diesel engine 1 is in a transient state, purification of the exhaust gas G can be achieved without a time delay.

なお、本発明の排気浄化装置の制御方法は、上述した実施の形態だけに特に限定されるものではなく、本発明の要旨を逸脱しない範囲において変更を加え得ることは勿論である。   It should be noted that the control method for the exhaust emission control device of the present invention is not particularly limited to the above-described embodiment, and it goes without saying that changes can be made without departing from the scope of the present invention.

本発明の排気浄化装置の制御方法は、様々な車種に適用できる。   The control method of the exhaust emission control device of the present invention can be applied to various vehicle types.

本発明の対象となる排気浄化装置の一例を示す概念図である。It is a conceptual diagram which shows an example of the exhaust gas purification apparatus used as the object of this invention. 図１における制御ユニットのフローチャートである。It is a flowchart of the control unit in FIG. 触媒温度とＮＯｘ低減率の関係を示す線図である。It is a diagram which shows the relationship between a catalyst temperature and a NOx reduction rate.

符号の説明Explanation of symbols

１ ディーゼルエンジン
６ 吸気経路
７ 排気経路
１４ ＮＯｘ還元触媒
Ｇ 排気
Ｕ 尿素水（還元剤） 1 Diesel Engine 6 Intake Route 7 Exhaust Route 14 NOx Reduction Catalyst G Exhaust U Urea Water (Reducing Agent)

Claims (2)

エンジン排気経路に組み込んであるＮＯｘ還元触媒の上流側へ還元剤を添加し、排気中のＮＯｘの還元浄化を図る排気浄化装置の制御方法であって、触媒温度が所定の温度域を下回った際に、エンジン吸気経路へ送給する排気の再循環量を増加させ、触媒温度が所定の温度域を上回った際に、エンジン吸気経路へ送給する排気の再循環量を減少させ、これに加えて、エンジン負荷が高くなるときに、排気温度が下がるように燃料噴射を行ない、エンジン負荷が低くなるときに、排気温度が上がるように燃料噴射を行なうことを特徴とする排気浄化装置の制御方法。   A control method for an exhaust gas purification apparatus for reducing and purifying NOx in exhaust gas by adding a reducing agent to the upstream side of a NOx reduction catalyst incorporated in an engine exhaust path when the catalyst temperature falls below a predetermined temperature range In addition, the recirculation amount of exhaust gas supplied to the engine intake path is increased, and when the catalyst temperature exceeds a predetermined temperature range, the recirculation amount of exhaust gas supplied to the engine intake path is decreased. A control method for an exhaust emission control device, wherein fuel injection is performed such that the exhaust temperature decreases when the engine load increases, and fuel injection is performed so that the exhaust temperature increases when the engine load decreases. . 触媒温度が所定の温度域に達し且つエンジン負荷が低くなるときに、エンジン吸気経路へ送給する排気の再循環量を増加させ、排気温度が高くなるように燃料噴射を行なう請求項１に記載の排気浄化装置の制御方法。   2. The fuel injection is performed according to claim 1, wherein when the catalyst temperature reaches a predetermined temperature range and the engine load becomes low, the recirculation amount of the exhaust gas supplied to the engine intake passage is increased and the exhaust temperature is increased. Control method for exhaust gas purification apparatus.
JP2004215765A 2004-07-23 2004-07-23 Control method for exhaust emission control device Pending JP2006037769A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008002355A (en) * 2006-06-22 2008-01-10 Hino Motors Ltd Exhaust emission control device
JP2008128115A (en) * 2006-11-21 2008-06-05 Toyota Motor Corp Exhaust emission control system for internal combustion engine
JP2010168942A (en) * 2009-01-21 2010-08-05 Nissan Motor Co Ltd Control device and control method of temperature of exhaust gas recirculation of internal combustion engine
WO2011145566A1 (en) * 2010-05-17 2011-11-24 いすゞ自動車株式会社 Fuel injection control device for engine equipped with selective reduction catalyst device
WO2014064791A1 (en) 2012-10-25 2014-05-01 三菱重工業株式会社 Diesel engine control device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008002355A (en) * 2006-06-22 2008-01-10 Hino Motors Ltd Exhaust emission control device
JP2008128115A (en) * 2006-11-21 2008-06-05 Toyota Motor Corp Exhaust emission control system for internal combustion engine
JP2010168942A (en) * 2009-01-21 2010-08-05 Nissan Motor Co Ltd Control device and control method of temperature of exhaust gas recirculation of internal combustion engine
WO2011145566A1 (en) * 2010-05-17 2011-11-24 いすゞ自動車株式会社 Fuel injection control device for engine equipped with selective reduction catalyst device
WO2014064791A1 (en) 2012-10-25 2014-05-01 三菱重工業株式会社 Diesel engine control device
US9410495B2 (en) 2012-10-25 2016-08-09 Mitsubishi Heavy Industries, Ltd. Diesel engine control apparatus

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