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JP4327072B2 - Liquid reductant discrimination system for exhaust purification system - Google Patents

Liquid reductant discrimination system for exhaust purification system Download PDF

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JP4327072B2
JP4327072B2 JP2004335446A JP2004335446A JP4327072B2 JP 4327072 B2 JP4327072 B2 JP 4327072B2 JP 2004335446 A JP2004335446 A JP 2004335446A JP 2004335446 A JP2004335446 A JP 2004335446A JP 4327072 B2 JP4327072 B2 JP 4327072B2
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reducing agent
liquid reducing
pipe
flow rate
sensor
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JP2006144657A (en
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公信 平田
友康 原田
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UD Trucks Corp
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UD Trucks Corp
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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
    • F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
    • 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
    • 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
    • F01N13/0097—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 the purifying devices are arranged in a single housing
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

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

Description

本発明は、ディーゼルやガソリンエンジン等の排気に含まれるＮＯｘを除去する排気浄化装置に係り、特に、選択還元触媒（ＳＣＲ）を採用した排気浄化装置における液体還元剤について適正なものかどうか判別するための技術に関する。   The present invention relates to an exhaust purification device that removes NOx contained in exhaust gas from a diesel engine, a gasoline engine, or the like, and in particular, determines whether or not a liquid reducing agent in an exhaust purification device employing a selective reduction catalyst (SCR) is appropriate. For technology.

エンジンの排気に含まれるＮＯｘを除去する排気浄化装置として、特許文献１に開示されたようなＳＣＲを採用した排気浄化装置が提案されている。この排気浄化装置は、排気系に還元触媒を配設し、該還元触媒の排気上流に還元剤を噴射し添加することにより、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ものである。還元剤は、常温において液体状態で貯蔵用のタンクに貯蔵され、エンジン運転状態に対応した添加量が噴射ノズルから噴射される。その還元反応は、ＮＯｘと反応性が良好なアンモニアを用いるものであり、このための還元剤としては、排気熱及び排気中の水蒸気により加水分解してアンモニアを容易に発生する尿素水溶液やアンモニア水溶液、又はＨＣ系などの液体還元剤が用いられる。   As an exhaust purification device that removes NOx contained in engine exhaust, an exhaust purification device that employs an SCR as disclosed in Patent Document 1 has been proposed. In this exhaust purification device, a reduction catalyst is disposed in an exhaust system, and a reducing agent is injected and added upstream of the reduction catalyst to cause a catalytic reduction reaction between NOx in the exhaust and the reducing agent, thereby reducing NOx. It purifies to harmless components. The reducing agent is stored in a storage tank in a liquid state at room temperature, and an addition amount corresponding to the engine operating state is injected from the injection nozzle. The reduction reaction uses ammonia having good reactivity with NOx, and as a reducing agent therefor, an aqueous urea solution or aqueous ammonia solution that easily generates ammonia by hydrolysis with exhaust heat and water vapor in the exhaust. Alternatively, a liquid reducing agent such as HC is used.

このような液体還元剤を使用する排気浄化装置では、適正な溶液濃度の液体還元剤が使用されていないと、触媒上での還元反応が不完全となり、ＮＯｘ排出量の増加といった事態が予想される。すなわち、タンク内の液体還元剤が水で薄めてあったり、水などの異種溶液がタンク内に入れてあったり、タンク内が空であったりすると、排気浄化装置本来の能力を発揮できない。   In such an exhaust purification device using a liquid reducing agent, if a liquid reducing agent having an appropriate solution concentration is not used, the reduction reaction on the catalyst becomes incomplete, and a situation such as an increase in NOx emission is expected. The That is, if the liquid reducing agent in the tank is diluted with water, a different solution such as water is put in the tank, or the tank is empty, the original ability of the exhaust gas purification device cannot be exhibited.

そこで、タンク内に貯蔵されている液体還元剤が適正なものであるかどうか判別するために、タンク内液体の濃度を測定し、その測定結果から適正かどうか判別して運転者への警告やシステム停止等の異常対応をとるようにしている。この濃度測定は、離間した２点間の熱伝達特性を計測するセンサを液体還元剤のタンク内に設置し、その計測値を溶液濃度に換算することにより行っている。
特開２０００−０２７６２７号公報 Therefore, in order to determine whether the liquid reducing agent stored in the tank is appropriate, the concentration of the liquid in the tank is measured, and from the measurement result, it is determined whether it is appropriate. We are trying to deal with abnormalities such as system shutdown. This concentration measurement is performed by installing a sensor for measuring a heat transfer characteristic between two spaced points in a liquid reducing agent tank and converting the measured value into a solution concentration.
JP 2000-027627 A

ところが、上記のような感熱式のセンサを使用する場合、その測定原理の故に、走行等による振動でタンク内の液体還元剤が揺れていると測定誤差が大きくなり、正常な判別が行えなくなるという課題がある。すなわち、揺れにより液体還元剤に対流が生じると、該還元剤を熱伝達媒体とした熱伝達特性が変化するので、熱伝達特性の変化に敏感な計測値の精度が低下する。そこで、タンク内の液体還元剤が揺れていない状態での判別を実現するか、もしくは、タンク内の液体還元剤の揺れに関係なく判別を行えるような仕組みを考える必要がある。   However, when using a thermal sensor as described above, due to the measurement principle, if the liquid reducing agent in the tank is shaken by vibration due to running or the like, the measurement error increases and normal discrimination cannot be performed. There are challenges. That is, when convection occurs in the liquid reducing agent due to shaking, the heat transfer characteristic using the reducing agent as a heat transfer medium changes, and the accuracy of the measurement value sensitive to the change in the heat transfer characteristic decreases. Therefore, it is necessary to consider a mechanism for realizing the determination in a state where the liquid reducing agent in the tank is not shaken, or performing the determination irrespective of the shaking of the liquid reducing agent in the tank.

本発明はこのような背景に基づき案出されたものであって、タンク内の液体還元剤が揺れているかどうかに関係なく、適正な液体還元剤かどうかを判別することのできる液体還元剤判別システムを提供する。   The present invention has been devised based on such a background, and it is possible to determine whether or not the liquid reducing agent is an appropriate liquid reducing agent regardless of whether or not the liquid reducing agent in the tank is shaking. Provide a system.

本発明によれば、タンクに貯蔵された液体還元剤を移送する配管の所定箇所に、離間した２点間の熱伝達特性を計測するセンサを設け、該センサの計測値と配管内の液体還元剤流速とから液体還元剤が適正かどうか判別することを特徴とした排気浄化装置の液体還元剤判別システムを提案する。
具体的には、センサの計測値を配管内の液体還元剤流速に応じて溶液濃度に換算し、該溶液濃度から液体還元剤が適正かどうか判別する、あるいは、センサの計測値が、配管内の液体還元剤流速において適正な液体還元剤であることを示す計測値の範囲にあるかどうかを判断することにより、液体還元剤が適正かどうか判別する方式とすることができる。 According to the present invention, a sensor for measuring heat transfer characteristics between two spaced points is provided at a predetermined location of a pipe for transferring the liquid reducing agent stored in the tank, and the measured value of the sensor and the liquid reduction in the pipe A liquid reducing agent discriminating system for an exhaust emission control device is proposed, which discriminates whether or not a liquid reducing agent is appropriate from the agent flow rate.
Specifically, the measured value of the sensor is converted into a solution concentration according to the flow rate of the liquid reducing agent in the pipe, and it is determined from the solution concentration whether the liquid reducing agent is appropriate. By determining whether or not the liquid reducing agent is in the range of the measured value indicating that it is an appropriate liquid reducing agent at the flow rate of the liquid reducing agent, it can be determined whether or not the liquid reducing agent is appropriate.

この発明では、タンク内で計測する場合に比べてエンジン振動や走行振動による影響を受けにくい、配管中を流れる液体還元剤に対し感熱式のセンサによる計測を行うことを想起している。ただし、配管中を流れる液体還元剤の熱伝達特性を計測するため、上述のように感熱式のセンサの特性上、実測した計測値をそのままで判別したのでは誤判定を生じ得る。そこで、予め実験によりデータを収集するなどして、液体還元剤の流速に応じた補正を計測値に対し行って判別するという工夫を凝らしている。たとえば、データ収集により液体還元剤の流速に応じ補正した溶液濃度を予め取得し、該補正溶液濃度を流速毎に計測値に対応させてマッピングすることにより、実測に際しては、得られた計測値に対して流速に応じ補正済みの溶液濃度を読み出すようにする。あるいは、データ収集により、液体還元剤の流速毎に、適正な液体還元剤であることを示す計測値の範囲を予め取得し、実測された計測値が当該実測時の配管内の液体還元剤流速におけるその計測値範囲に入っているかどうかを判断するようにする。   In the present invention, it is recalled that the liquid reducing agent flowing in the pipe, which is less affected by the engine vibration and the traveling vibration as compared with the case of measuring in the tank, is measured by a thermal sensor. However, in order to measure the heat transfer characteristics of the liquid reducing agent flowing in the piping, erroneous determination may occur if the actually measured values are determined as they are because of the characteristics of the thermal sensor as described above. In view of this, a technique has been devised in which, for example, data is collected in advance by experiments, and correction is performed on the measured value according to the flow rate of the liquid reducing agent to make a determination. For example, by acquiring in advance the solution concentration corrected according to the flow rate of the liquid reducing agent by data collection, and mapping the corrected solution concentration corresponding to the measured value for each flow rate, the actual measured value is On the other hand, the corrected solution concentration is read according to the flow rate. Alternatively, by collecting data, a range of measured values indicating that the liquid reducing agent is an appropriate liquid reducing agent is obtained in advance for each flow rate of the liquid reducing agent, and the measured value is the liquid reducing agent flow rate in the pipe at the time of the actual measurement. It is determined whether or not it is within the measurement value range.

このような液体還元剤判別システムは、センサの計測値と溶液濃度とを液体還元剤の流速毎にマッピングして記憶した記憶手段と、センサにより実測された計測値に対応する溶液濃度を、該実測時の配管内の液体還元剤流速に従って記憶手段から読み出す制御手段と、を備えた構成とすることができる。あるいは、液体還元剤の流速毎に、適正な液体還元剤であることを示すセンサの計測値範囲を記憶した記憶手段と、センサにより実測された計測値が記憶手段に記憶された計測値範囲かどうかを、該実測時の配管内の液体還元剤流速に従って判断する制御手段と、を備えた構成とすることができる。この計測値の範囲を判断する態様の場合、記憶手段にはその範囲かどうかのデータ、つまり、上下限の計測値あるいは当該範囲内の全計測値を流速毎に記憶すれば良いので、記憶容量を少なくすませることができる。   Such a liquid reducing agent discriminating system includes a storage means that maps and stores the measured value of the sensor and the solution concentration for each flow rate of the liquid reducing agent, and the solution concentration corresponding to the measured value measured by the sensor. And a control unit that reads from the storage unit according to the liquid reducing agent flow rate in the pipe at the time of actual measurement. Alternatively, for each flow rate of the liquid reducing agent, a storage means that stores a measurement value range of a sensor indicating that the liquid reducing agent is an appropriate liquid reducing agent, and a measurement value range that is measured by the sensor is stored in the storage means. And a control means for determining whether or not according to the flow rate of the liquid reducing agent in the pipe at the time of actual measurement. In the case of the mode for determining the range of the measurement value, the storage means only has to store the data indicating whether or not the range is satisfied, that is, the upper and lower limit measurement values or all the measurement values within the range. Can be reduced.

これら本発明の液体還元剤判別システムでは、実測時における配管内の液体還元剤流速について、エンジン運転状態に応じて決定される液体還元剤の添加量及び配管の断面積から得ることができる。すなわち、添加量＝流量なので、配管の断面積がわかっていればこの添加量から算出することができる。   In these liquid reducing agent discrimination systems of the present invention, the liquid reducing agent flow rate in the pipe at the time of actual measurement can be obtained from the addition amount of the liquid reducing agent determined according to the engine operating state and the cross-sectional area of the pipe. That is, since the addition amount = flow rate, if the cross-sectional area of the pipe is known, it can be calculated from this addition amount.

本発明では、所定の流速で流れている、つまり流速がわかっている液体還元剤に対し、感熱式のセンサによる熱伝達特性の計測を行うようにしている。排気浄化装置における配管中の液体還元剤流量つまり流速は、ＥＣＵにより状況に応じて制御されており、したがって走行振動、エンジン振動から大きな影響を受けにくいと言える。すなわち、配管内を流れている液体還元剤に対し計測を行ってその流速に応じ判別するようにしたことにより、走行、停止に関わらず誤判定が抑制された判別を行うことができる。その結果、本来の排気浄化装置の性能を維持して、ＮＯｘ排出抑制に貢献する。   In the present invention, heat transfer characteristics are measured by a thermal sensor for a liquid reducing agent that flows at a predetermined flow rate, that is, the flow rate is known. The flow rate of the liquid reducing agent in the pipe, that is, the flow velocity in the exhaust purification apparatus is controlled by the ECU according to the situation, and therefore it can be said that the liquid reducing agent flow rate is not easily affected by the running vibration and the engine vibration. That is, by measuring the liquid reducing agent flowing in the pipe and determining according to the flow velocity, it is possible to perform determination in which erroneous determination is suppressed regardless of running or stopping. As a result, the performance of the original exhaust gas purification device is maintained and it contributes to NOx emission suppression.

図１に、本発明に係る排気浄化装置の概略図を示している。図示の排気浄化装置は、排気系に上流側から順に介装された酸化触媒１、ＮＯｘ浄化触媒２及びＮＨ３スリップ触媒３を備えている。そして、ＮＯｘ浄化触媒２よりも上流側の排気中にノズル４から液体還元剤を噴射して添加する構成をもち、ノズル４へ適量の液体還元剤を供給するための制御弁を備えた添加装置５と、排気温センサ６，７による排気温やエンジンのＥＣＵ８から得られるエンジン回転速度等に応じて添加装置５の供給制御を行うＥＣＵ９（制御手段）と、を備えている。 FIG. 1 shows a schematic diagram of an exhaust emission control device according to the present invention. The illustrated exhaust purification device includes an oxidation catalyst 1, an NOx purification catalyst 2, and an NH 3 slip catalyst 3 that are interposed in the exhaust system in order from the upstream side. The addition device has a configuration in which the liquid reducing agent is injected from the nozzle 4 into the exhaust gas upstream of the NOx purification catalyst 2 and includes a control valve for supplying an appropriate amount of the liquid reducing agent to the nozzle 4. 5 and an ECU 9 (control means) for controlling supply of the adding device 5 in accordance with the exhaust temperature by the exhaust temperature sensors 6 and 7, the engine speed obtained from the engine ECU 8, and the like.

液体還元剤としてはたとえば尿素水を使用するものであるが、ノズル４から噴射された尿素水は排気管内の排気熱により加水分解してアンモニアを容易に発生し、得られたアンモニアがＮＯｘ浄化触媒２において排気中のＮＯｘと反応することで、水及び無害なガスに浄化される。尿素水は、固体もしくは粉体の尿素の水溶液として貯蔵される。
このような尿素水あるいはアンモニア水溶液等の上述したような各種液体還元剤は、タンク１０に貯蔵されており、タンク１０から配管１１を介し添加装置５を経てノズル４へ移送される。その配管１１の途中に、離間した２点間の熱伝達特性を計測する感熱式のセンサ１２が介装されている。配管１１の所定箇所にセンサ１２を配置して、配管１１内を流れている液体還元剤の熱伝達特性を計測するので、タンク１０内で計測する場合に比べてエンジン振動や走行信号による影響を受けにくい。 For example, urea water is used as the liquid reducing agent, but the urea water injected from the nozzle 4 is hydrolyzed by the exhaust heat in the exhaust pipe to easily generate ammonia, and the obtained ammonia is converted into a NOx purification catalyst. By reacting with NOx in the exhaust gas in 2, it is purified into water and harmless gas. The urea water is stored as an aqueous solution of solid or powdered urea.
Such various liquid reducing agents as described above, such as urea water or ammonia aqueous solution, are stored in the tank 10 and transferred from the tank 10 to the nozzle 4 via the pipe 11 via the adding device 5. In the middle of the pipe 11, a thermal sensor 12 for measuring heat transfer characteristics between two spaced points is interposed. Since the sensor 12 is arranged at a predetermined position of the pipe 11 and the heat transfer characteristic of the liquid reducing agent flowing in the pipe 11 is measured, the influence of the engine vibration and the traveling signal is affected as compared with the case of measuring in the tank 10. It is hard to receive.

ただし、流れている液体還元剤に対し計測を行うので、感熱式のセンサ１２の特性上、実測値をそのまま溶液濃度に換算して判別したのでは誤判定を生じ得る。そこで、液体還元剤判別システムの制御手段となるＥＣＵ９は、図２に示す処理フローを実行して、センサ１２による計測値から液体還元剤の適正判別を行う。
ＥＣＵ９は、ステップ２０でイグニッションキーによる始動等に伴い処理フローをスタートし、まず最初にステップ２１で、イグニッションスイッチがオンになっているかどうかを確認することにより、エンジンが運転状態にあり、液体還元剤の添加制御が行われていることを確認する。 However, since the measurement is performed on the flowing liquid reducing agent, an erroneous determination may occur if the actual measurement value is converted into the solution concentration as it is and determined due to the characteristics of the thermal sensor 12. Therefore, the ECU 9 serving as the control means of the liquid reducing agent discrimination system executes the processing flow shown in FIG.
The ECU 9 starts the processing flow in accordance with the start by the ignition key in step 20, and first checks in step 21 whether or not the ignition switch is on, so that the engine is in operation and the liquid reduction is performed. Confirm that the addition control of the agent is performed.

継いでステップ２２へ進み、センサ１２により実測された計測値Ｘを取得する。計測値Ｘが得られるとＥＣＵ９は、ステップ２３で、当該実測時における液体還元剤の添加量を取得する。液体還元剤の添加量は、添加装置５に対する現在の添加量指示値から得ることができる。そしてステップ２４で、得られた添加量から配管１１内の液体還元剤流速Ｙを算出する。この演算では、添加量（ｍ３／Ｓ）を配管１１の断面積（ｍ２）で除算することにより、流速（ｍ／ｓ）を得る。 Then, the process proceeds to step 22 where the measured value X actually measured by the sensor 12 is acquired. When the measured value X is obtained, the ECU 9 obtains the amount of liquid reducing agent added at the time of actual measurement in step 23. The addition amount of the liquid reducing agent can be obtained from the current addition amount instruction value for the addition device 5. In step 24, the liquid reducing agent flow velocity Y in the pipe 11 is calculated from the obtained addition amount. In this calculation, the flow rate (m / s) is obtained by dividing the addition amount (m 3 / S) by the cross-sectional area (m 2 ) of the pipe 11.

実測時の液体還元剤流速Ｙが算出されるとステップ２５へ進んで、ＲＯＭ等の不揮発性メモリからなる記憶手段へ予め記憶されている相関データＤを参照して、流速Ｙにおける計測値Ｘに該当する溶液濃度（％）を読み出す。相関データＤは、所定の流速で溶液濃度を変えた液体還元剤を流し、該流れている液体還元剤につきセンサ１２から得られる計測値を予め収集しておいたデータで、所定の流速毎に計測値と溶液濃度との関係を設定したマップである。したがって、計測値Ｘと流速Ｙをアドレスにしてマップを検索すると、補正された溶液濃度を読み出すことができる。   When the liquid reducing agent flow velocity Y at the time of actual measurement is calculated, the process proceeds to step 25, and the measured value X at the flow velocity Y is obtained by referring to the correlation data D stored in advance in the storage means including a nonvolatile memory such as a ROM. Read the corresponding solution concentration (%). Correlation data D is data in which a liquid reducing agent whose solution concentration is changed at a predetermined flow rate is flowed, and measurement values obtained from the sensor 12 for the flowing liquid reducing agent are collected in advance. It is the map which set the relationship between a measured value and a solution concentration. Therefore, when the map is searched using the measured value X and the flow velocity Y as addresses, the corrected solution concentration can be read out.

この相関データＤに基づいて、流速に従い計測値から溶液濃度を読み出せば、これは流速に応じて補正された溶液濃度である。したがってステップ２６で、当該溶液濃度から適正な液体還元剤かどうかを判別して判別結果を出力し、ステップ２７でＲＡＭ等のメモリへ記憶する。続くステップ２８ではリターンし、フローを繰り返す。
相関データＤについては、上記のようなマップの他に、適正な溶液濃度の液体還元剤を配管１１に設けたセンサ１２で計測したときに、センサ１２の誤差等も考慮に入れて得られる計測値の範囲を、予め流速毎に収集してそれぞれ記憶しておく手法も可能である。すなわち、上記のようにして収集されたデータから、流速毎に適正な溶液濃度に対し得られる計測値の範囲を抽出し、その上下限値、あるいは、当該範囲内の全計測値を流速毎にまとめてマップとし相関データＤとする。そしてステップ２５では、実測された計測値Ｘが、該当する流速Ｙにおいて適正な液体還元剤であることを示す計測値の範囲にあるかどうかを相関データＤに照らして判断し、範囲内であればＯＫ（適正な液体還元剤が使われている）、範囲外であればＮＧ（適正な還元剤が使われていない）をステップ２６で判別結果として出すようにしてもよい。この場合は、記憶手段における記憶容量をより少なくすることができる。 If the solution concentration is read from the measured value according to the flow rate based on the correlation data D, this is the solution concentration corrected according to the flow rate. Therefore, in step 26, it is determined whether or not the liquid reducing agent is an appropriate liquid reducing agent from the solution concentration, and the determination result is output. In the following step 28, the process returns and the flow is repeated.
For the correlation data D, in addition to the map as described above, when the liquid reducing agent having an appropriate solution concentration is measured by the sensor 12 provided in the pipe 11, the measurement obtained by taking the error of the sensor 12 into consideration. It is also possible to collect a range of values for each flow velocity and store them in advance. That is, from the data collected as described above, a range of measurement values obtained for an appropriate solution concentration at each flow rate is extracted, and the upper and lower limit values, or all measurement values within the range are extracted for each flow rate. The map is collectively used as correlation data D. In step 25, whether or not the actually measured value X is within the range of the measured value indicating that it is an appropriate liquid reducing agent at the corresponding flow velocity Y is determined in light of the correlation data D. If it is OK (appropriate liquid reducing agent is used), if it is out of range, NG (no appropriate reducing agent is used) may be output as a discrimination result in step 26. In this case, the storage capacity in the storage unit can be further reduced.

本発明に係る排気浄化装置の概略図。1 is a schematic view of an exhaust purification device according to the present invention. 本発明に係る液体還元剤判別過程の一例を説明するフローチャート。The flowchart explaining an example of the liquid reducing agent discrimination | determination process based on this invention.

符号の説明Explanation of symbols

９ ＥＣＵ（制御手段）
１０ タンク
１１ 配管
１２ 感熱式のセンサ 9 ECU (control means)
10 Tank 11 Piping 12 Thermal sensor

Claims (5)

タンクに貯蔵された液体還元剤を移送する配管の所定箇所に、離間した２点間の熱伝達特性を計測するセンサを設け、
前記センサの計測値を前記配管内の液体還元剤流速に応じて溶液濃度に換算し、該溶液濃度から液体還元剤が適正かどうか判別する
ことを特徴とする排気浄化装置の液体還元剤判別システム。 A sensor for measuring heat transfer characteristics between two spaced points is provided at a predetermined location of a pipe for transferring the liquid reducing agent stored in the tank,
A liquid reducing agent discriminating system for an exhaust gas purification apparatus, wherein a measured value of the sensor is converted into a solution concentration according to a flow rate of the liquid reducing agent in the pipe, and the liquid reducing agent is discriminated from the solution concentration. . 前記センサの計測値と溶液濃度とを液体還元剤の流速毎にマッピングして記憶した記憶手段と、
前記センサにより実測された計測値に対応する溶液濃度を、該実測時の前記配管内の液体還元剤流速に従って前記記憶手段から読み出す制御手段と、
を備えることを特徴とする請求項１記載の排気浄化装置の液体還元剤判別システム。 Storage means for mapping and storing the measured value of the sensor and the solution concentration for each flow rate of the liquid reducing agent;
Control means for reading the solution concentration corresponding to the measured value measured by the sensor from the storage means according to the flow rate of the liquid reducing agent in the pipe at the time of the actual measurement;
The liquid reducing agent discriminating system for an exhaust emission control device according to claim 1, comprising: タンクに貯蔵された液体還元剤を移送する配管の所定箇所に、離間した２点間の熱伝達特性を計測するセンサを設け、
前記センサの計測値が、前記配管内の液体還元剤流速において適正な液体還元剤であることを示す計測値の範囲にあるかどうかを判断することにより、液体還元剤が適正かどうか判別する
ことを特徴とする排気浄化装置の液体還元剤判別システム。 A sensor for measuring heat transfer characteristics between two spaced points is provided at a predetermined location of a pipe for transferring the liquid reducing agent stored in the tank,
It is determined whether or not the liquid reducing agent is appropriate by determining whether or not the measured value of the sensor is within a range of measured values indicating that it is an appropriate liquid reducing agent at the flow rate of the liquid reducing agent in the pipe.
A liquid reducing agent discriminating system for an exhaust emission control device. 液体還元剤の流速毎に、適正な液体還元剤であることを示す前記センサの計測値範囲を記憶した記憶手段と、
前記センサにより実測された計測値が前記記憶手段に記憶された計測値範囲かどうかを、該実測時の前記配管内の液体還元剤流速に従って判断する制御手段と、
を備えることを特徴とする請求項３記載の排気浄化装置の液体還元剤判別システム。 Storage means for storing a measurement value range of the sensor indicating that the flow rate of the liquid reducing agent is an appropriate liquid reducing agent;
Control means for determining whether the measured value measured by the sensor is in the measured value range stored in the storage means according to the flow rate of the liquid reducing agent in the pipe at the time of the actual measurement;
The liquid reducing agent discriminating system for an exhaust emission control device according to claim 3, comprising: 前記配管内の液体還元剤流速を、液体還元剤の添加量及び前記配管の断面積から算出する請求項１〜４のいずれか１項に記載の排気浄化装置の液体還元剤判別システム。 The liquid reducing agent discriminating system for an exhaust gas purification apparatus according to any one of claims 1 to 4 , wherein the flow rate of the liquid reducing agent in the pipe is calculated from an addition amount of the liquid reducing agent and a cross-sectional area of the pipe.
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