JP2020106002A - Diagnostic device and exhaust emission control device for internal combustion engine - Google Patents

Diagnostic device and exhaust emission control device for internal combustion engine Download PDF

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JP2020106002A
JP2020106002A JP2018247017A JP2018247017A JP2020106002A JP 2020106002 A JP2020106002 A JP 2020106002A JP 2018247017 A JP2018247017 A JP 2018247017A JP 2018247017 A JP2018247017 A JP 2018247017A JP 2020106002 A JP2020106002 A JP 2020106002A
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concentration
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value
selective reduction
reduction catalyst
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JP7197353B2 (en
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隆裕 田辺
Takahiro Tanabe
隆裕 田辺
寿子 岡崎
Toshiko Okazaki
寿子 岡崎
康彰 赤羽
Yasuaki Akabane
康彰 赤羽
尚裕 久柴
Naohiro Hisashiba
尚裕 久柴
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Bosch Corp
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    • 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
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    • 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
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    • Y02T10/10—Internal combustion engine [ICE] based vehicles
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Abstract

To provide a diagnostic device capable of improving detection accuracy of an abnormality such as missing and deterioration, etc. of an NOX selective reduction catalyst provided in an exhaust passage downstream of an NOX occlusion catalyst and an exhaust emission control device for an internal combustion engine.SOLUTION: A diagnostic device diagnosing an abnormality of an NOX selective reduction catalyst in an exhaust emission control device having an NOX occlusion catalyst and an NOX selective reduction catalyst which are provided in an exhaust passage of an internal combustion engine from an upstream side in this order includes: a downstream side NOX concentration estimation section calculating a downstream side NOX concentration estimation value that is an estimated value of an NOX concentration in the exhaust passage downstream of the NOX selective reduction catalyst; a sensor value detection section that acquires a sensor value of an NOX concentration sensor provided in the exhaust passage downstream of the NOX selective reduction catalyst; and a determination section determining an abnormality of the NOX selective reduction catalyst on the basis of the downstream side NOX concentration estimation value and the sensor value.SELECTED DRAWING: Figure 3

Description

本発明は、診断装置及び内燃機関の排気浄化装置に関する。 The present invention relates to a diagnostic device and an exhaust gas purification device for an internal combustion engine.

ディーゼルエンジン等の内燃機関の排気中に含まれる窒素酸化物（ＮＯX）を還元して排気を浄化する部材として、ＮＯX吸蔵触媒及びＮＯX選択還元触媒が知られている。ＮＯX吸蔵触媒は、内燃機関で燃焼される混合気が理論空燃比（ストイキ）に対して燃料希薄（リーン）状態のときに排気中のＮＯXを吸蔵し、混合気がストイキ状態又は燃料過濃（リッチ）状態のときにＮＯXを放出して、排気中の未燃炭化水素（ＨＣ：Hydrocarbon）と反応させることにより、ＮＯXを窒素（Ｎ2）に還元する。ＮＯX選択還元触媒は、ＮＯXの還元成分としてのアンモニア（ＮＨ3）を吸着する機能を有し、流入する排気中のＮＯXをＮＨ3と反応させることにより、ＮＯXをＮ2に還元する。 A NO x storage catalyst and a NO x selective reduction catalyst are known as members for purifying the exhaust by reducing nitrogen oxides (NO x ) contained in the exhaust of an internal combustion engine such as a diesel engine. The NO X storage catalyst occludes NO X in the exhaust gas when the air-fuel mixture combusted in the internal combustion engine is fuel-lean (lean) state with respect to the stoichiometric air-fuel ratio (stoichiometric) air-fuel mixture over stoichiometric state or fuel In a rich state, NO X is released and reacted with unburned hydrocarbon (HC: Hydrocarbon) in the exhaust gas to reduce NO X to nitrogen (N 2 ). The NO X selective reducing catalyst has a function of adsorbing ammonia (NH 3) as a reducing component of NO X, by reaction with NH 3 and NO X in the inflowing exhaust gas, reduce NO X to N 2 To do.

例えば、特許文献１には、内燃機関の排気を浄化する排気浄化装置の一態様として、ＮＯX吸蔵触媒及びＮＯX選択還元触媒をともに備えた排気浄化装置が開示されている。具体的に、特許文献１に開示された排気浄化装置では、ＮＯX吸蔵触媒とＮＯX選択還元触媒とがこの順に排気通路の上流側から順に配置されている。かかる排気浄化装置においては、ＮＯX吸蔵触媒でのＮＯXとＨＣとの反応によりＮＨ3が生成される場合に、ＮＯX選択還元触媒が当該ＮＨ3を吸着する。そして、ＮＯX吸蔵触媒からＮＯXが流出する場合に、ＮＯX選択還元触媒はＮＨ3を用いてＮＯXを還元する。 For example, Patent Document 1 discloses an exhaust gas purification device that includes both a NO x storage catalyst and a NO x selective reduction catalyst as one mode of an exhaust gas purification device that purifies the exhaust gas of an internal combustion engine. Specifically, in the exhaust gas purification device disclosed in Patent Document 1, the NO X storage catalyst and the NO X selective reduction catalyst are arranged in this order from the upstream side of the exhaust passage. In such an exhaust emission control device, when NH 3 is produced by the reaction of NO X and HC in the NO X storage catalyst, the NO X selective reduction catalyst adsorbs the NH 3 . When the NO X flows out from the NO X storing catalyst, NO X selective reduction catalyst for reducing NO X using NH 3.

特表２００６−５２２２５７号公報Japanese Patent Publication No. 2006-522257

ここで、特許文献１に開示された排気浄化装置では、ＮＯX選択還元触媒の劣化が進んだ場合やＮＯX選択還元触媒が欠落（未装着）している場合、大気中へのＮＯXやＮＨ3の放出量が増大するおそれがある。このため、ＮＯX選択還元触媒の欠落又は劣化を検出可能な診断機能があれば有意義である。 Here, in the exhaust emission control device disclosed in Patent Document 1, when deterioration of the NO X selective reduction catalyst progresses or when the NO X selective reduction catalyst is missing (not installed), NO X in the atmosphere and The amount of released NH 3 may increase. Therefore, it is meaningful if there is a diagnostic function capable of detecting the loss or deterioration of the NO X selective reduction catalyst.

例えば、ＮＯX選択還元触媒が熱容量を持つことを利用して、ＮＯX選択還元触媒よりも下流側に温度センサを設け、ＮＯX選択還元触媒の熱容量を考慮して作成した温度モデルと温度センサによる検出温度とを比較することにより、ＮＯX選択還元触媒の欠落を判定することが考えられる。 For example, the NO X selective reducing catalyst by utilizing the fact that with a heat capacity, the temperature sensor provided on the downstream side of the NO X selective reducing catalyst, the NO X selective reducing catalyst temperature model and a temperature sensor capacity created in consideration of the It is conceivable to determine the lack of the NO X selective reduction catalyst by comparing the detected temperature by

しかしながら、温度モデルと検出温度とを比較する方法の場合、診断結果の精度を高めるには、排気の温度変化が比較的少ない運転状態で診断を実行する必要があり、診断を実行可能な運転状態が限定的となる。また、ＮＯX選択還元触媒が劣化しても熱容量の変化は少ないことから、温度モデルと検出温度とを比較する方法の場合、ＮＯX選択還元触媒の欠落を検出することができる一方、ＮＯX選択還元触媒の劣化を検出することは困難である。 However, in the case of the method of comparing the temperature model and the detected temperature, in order to improve the accuracy of the diagnosis result, it is necessary to execute the diagnosis in the operating state in which the temperature change of the exhaust gas is relatively small, and the operating state in which the diagnosis can be performed Will be limited. Further, NO changes in X selective reduction catalyst also deteriorates heat capacity since less, if the method of comparing the temperature model and the detected temperature, while it is possible to detect the missing of the NO X selective reduction catalyst, NO X It is difficult to detect deterioration of the selective reduction catalyst.

本発明は、上記問題に鑑みてなされたものであり、本発明の目的とするところは、ＮＯX吸蔵触媒よりも下流側の排気通路に備えられたＮＯX選択還元触媒の欠落や劣化等の異常の検出精度を向上可能な診断装置及び内燃機関の排気浄化装置を提供することにある。 The present invention has been made in view of the above problems, and an object of the present invention is to eliminate or deteriorate the NO X selective reduction catalyst provided in the exhaust passage downstream of the NO X storage catalyst. An object of the present invention is to provide a diagnostic device and an exhaust gas purification device for an internal combustion engine that can improve the detection accuracy of an abnormality.

上記課題を解決するために、本発明のある観点によれば、内燃機関の排気通路に上流側から順にＮＯX吸蔵触媒とＮＯX選択還元触媒とを備えた排気浄化装置におけるＮＯX選択還元触媒の異常を診断する診断装置において、ＮＯX選択還元触媒よりも下流側の排気通路内のＮＯX濃度の推定値である下流側ＮＯX濃度推定値を算出する下流側ＮＯX濃度推定部と、ＮＯX選択還元触媒よりも下流側の排気通路に備えられたＮＯX濃度センサのセンサ値を取得するセンサ値検出部と、下流側ＮＯX濃度推定値及びセンサ値に基づいてＮＯX選択還元触媒の異常を判定する判定部と、を備える、診断装置が提供される。 In order to solve the above problems, according to an aspect of the present invention, the NO X selective reducing catalyst in the exhaust purification device provided in this order from the upstream side in an exhaust passage of an internal combustion engine and the NO X storage catalyst and the NO X selective reducing catalyst in the diagnostic apparatus for diagnosing an abnormality, and the downstream-side NO X density estimating unit that calculates a downstream NO X concentration estimated value is an estimated value of the NO X concentration in the exhaust passage downstream of the NO X selective reducing catalyst, a sensor value detector than the NO X selective reducing catalyst acquires a sensor value of the NO X concentration sensor provided in an exhaust passage downstream, the NO X selective reducing catalyst on the basis of the downstream-side NO X concentration estimated value and the sensor value There is provided a diagnostic device including: a determination unit that determines the abnormality.

また、上記課題を解決するために、本発明の別の観点によれば、内燃機関の排気通路に備えられたＮＯX吸蔵触媒と、ＮＯX吸蔵触媒よりも下流側の排気通路に備えられたＮＯX選択還元触媒と、ＮＯX選択還元触媒よりも下流側の排気通路に備えられたＮＯX濃度センサと、ＮＯX選択還元触媒の異常を診断する診断装置と、を備えた内燃機関の排気浄化装置において、診断装置は、ＮＯX選択還元触媒よりも下流側の排気通路内のＮＯX濃度の推定値である下流側ＮＯX濃度推定値を算出する下流側ＮＯX濃度推定部と、ＮＯX選択還元触媒よりも下流側の排気通路に備えられたＮＯX濃度センサのセンサ値を取得するセンサ値検出部と、下流側ＮＯX濃度推定値及びセンサ値に基づいてＮＯX選択還元触媒の異常を判定する判定部と、を備える、内燃機関の排気浄化装置が提供される。 In order to solve the above problems, according to another aspect of the present invention, a NO X storage catalyst provided in an exhaust passage of an internal combustion engine and an exhaust passage downstream of the NO X storage catalyst are provided. and the NO X selective reducing catalyst, the exhaust of the NO X selective and reducing NO X concentration sensor provided in an exhaust passage downstream of the catalyst, an internal combustion engine and a diagnostic apparatus for diagnosing an abnormality of the NO X selective reducing catalyst in purifier, diagnostic apparatus, and the downstream NO X density estimating unit that calculates a downstream NO X concentration estimated value is an estimated value of the NO X concentration in the exhaust passage downstream of the NO X selective reducing catalyst, NO a sensor value detector for obtaining a sensor value of the NO X concentration sensor provided in an exhaust passage on the downstream side of the X selective reducing catalyst, of the NO X selective reducing catalyst on the basis of the downstream-side NO X concentration estimated value and the sensor value An exhaust gas purification device for an internal combustion engine is provided that includes a determination unit that determines an abnormality.

以上説明したように本発明によれば、ＮＯX吸蔵触媒よりも下流側の排気通路に備えられたＮＯX選択還元触媒の欠落や劣化等の異常の検出精度を向上させることができる。 As described above, according to the present invention, it is possible to improve the accuracy of detecting an abnormality such as a loss or deterioration of the NO X selective reduction catalyst provided in the exhaust passage downstream of the NO X storage catalyst.

本実施形態に係る排気浄化装置の構成例を示す模式図である。It is a schematic diagram showing an example of composition of an exhaust gas purification device concerning this embodiment. 診断装置（制御装置）の構成例を示すブロック図である。It is a block diagram which shows the structural example of a diagnostic device (control device). 下流側ＮＯX濃度検出値の積算値の変化を示す説明図である。FIG. 6 is an explanatory diagram showing a change in an integrated value of downstream NO x concentration detection values. 診断装置（制御装置）の動作例を示すフローチャートである。It is a flow chart which shows an example of operation of a diagnostic device (control device).

以下に添付図面を参照しながら、本発明の好適な実施の形態について詳細に説明する。なお、本明細書及び図面において、実質的に同一の機能構成を有する構成要素については、同一の符号を付することにより重複説明を省略する。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, constituent elements having substantially the same functional configuration are designated by the same reference numerals, and a duplicate description will be omitted.

＜１．内燃機関の排気浄化装置の全体構成＞
本実施形態に係る内燃機関の排気浄化装置の構成例について説明する。図１は、排気浄化装置１０の構成例を示す模式図である。 <1. Overall Structure of Exhaust Gas Purification Device for Internal Combustion Engine>
An example of the configuration of the exhaust gas purification device for an internal combustion engine according to this embodiment will be described. FIG. 1 is a schematic diagram showing a configuration example of the exhaust emission control device 10.

排気浄化装置１０は、ディーゼルエンジン等に代表される内燃機関５の排気系に備えられる。本実施形態において、内燃機関５がディーゼルエンジンである例を説明する。内燃機関５は、各気筒に供給される燃料を噴射する燃料噴射システムを備える。燃料噴射システムは、例えば高圧の燃料を保持するコモンレールと、コモンレールに接続された複数の燃料噴射弁とを含むコモンレールシステムであってよい。ただし、内燃機関５は上記の構成例に限定されない。 The exhaust emission control device 10 is provided in an exhaust system of an internal combustion engine 5 represented by a diesel engine or the like. In the present embodiment, an example in which the internal combustion engine 5 is a diesel engine will be described. The internal combustion engine 5 includes a fuel injection system that injects fuel supplied to each cylinder. The fuel injection system may be, for example, a common rail system including a common rail that holds high-pressure fuel and a plurality of fuel injection valves connected to the common rail. However, the internal combustion engine 5 is not limited to the above configuration example.

内燃機関５の運転状態は、制御装置１００により制御される。内燃機関５では、燃焼される混合気の空燃比が、運転条件に応じてストイキ状態、燃料リーン状態又は燃料リッチ状態に切り換えられる。内燃機関５の排気には、ＮＯX、粒子状物質（ＰＭ）、一酸化炭素（ＣＯ）又はＨＣ等が含まれる。 The operating state of the internal combustion engine 5 is controlled by the control device 100. In the internal combustion engine 5, the air-fuel ratio of the air-fuel mixture to be burned is switched to the stoichiometric state, the fuel lean state or the fuel rich state according to the operating conditions. The exhaust gas of the internal combustion engine 5 contains NO x , particulate matter (PM), carbon monoxide (CO), HC, or the like.

排気浄化装置１０は、内燃機関５の排気管１１に配設された酸化触媒１９と、ＮＯX吸蔵触媒１５と、パティキュレートフィルタ１７と、ＮＯX選択還元触媒１３と、ＮＯX濃度センサ２３とを備える。酸化触媒１９、ＮＯX吸蔵触媒１５、パティキュレートフィルタ１７及びＮＯX選択還元触媒１３は、排気の流れの上流側からこの順に排気管１１に配設されている。 The exhaust gas purification device 10 includes an oxidation catalyst 19 arranged in an exhaust pipe 11 of the internal combustion engine 5, a NO x storage catalyst 15, a particulate filter 17, a NO x selective reduction catalyst 13, and a NO x concentration sensor 23. Equipped with. The oxidation catalyst 19, the NO x storage catalyst 15, the particulate filter 17, and the NO x selective reduction catalyst 13 are arranged in the exhaust pipe 11 in this order from the upstream side of the exhaust flow.

酸化触媒１９は、排気中に含まれるＨＣ、ＣＯ又はＮＯ等を酸化する。例えば、ＨＣ、ＣＯ又はＮＯは、Ｈ2Ｏ、ＣＯ2又はＮＯ2に酸化される。パティキュレートフィルタ１７は、排気中のＰＭを捕集するフィルタである。パティキュレートフィルタ１７に捕集されたＰＭは、適宜の時期に燃焼させられる。例えば内燃機関５の排気中に含まれる未燃のＨＣを増加させて酸化触媒１９で当該ＨＣが酸化する際に生じる酸化熱により排気温度を上昇させて、パティキュレートフィルタ１７に捕集されたＰＭを燃焼させる。なお、パティキュレートフィルタ１７に捕集されたＰＭを燃焼させる方法は、上記の例に限られない。 The oxidation catalyst 19 oxidizes HC, CO, NO or the like contained in the exhaust gas. For example, HC, CO or NO is oxidized to H 2 O, CO 2 or NO 2 . The particulate filter 17 is a filter that collects PM in the exhaust gas. The PM collected by the particulate filter 17 is burned at an appropriate time. For example, the unburned HC contained in the exhaust gas of the internal combustion engine 5 is increased to raise the exhaust gas temperature by the oxidation heat generated when the HC is oxidized by the oxidation catalyst 19, and the PM trapped in the particulate filter 17 is collected. To burn. The method of burning the PM trapped in the particulate filter 17 is not limited to the above example.

ＮＯX吸蔵触媒１５は、排気中のＮＯXをＨＣ及びＣＯと反応させることにより、ＮＯXをＮ2に変換する。具体的に、ＮＯX吸蔵触媒１５は、内燃機関５が燃料リーン状態のときに排気中のＮＯXを吸蔵し、内燃機関５が燃料リッチ状態のときに吸蔵していたＮＯXを放出して排気中のＨＣ及びＣＯによってＮＯXをＮ2へと変換する。ＮＯX吸蔵触媒１５におけるＮＯXの浄化時にはＮＨ3も生成される。 The NO X storage catalyst 15 converts NO X in the exhaust with HC and CO to convert NO X into N 2 . Specifically, the NO X storage catalyst 15 stores the NO X in the exhaust gas when the internal combustion engine 5 is in the fuel lean state, and releases the NO X stored when the internal combustion engine 5 is in the fuel rich state. The NO x is converted to N 2 by HC and CO in the exhaust gas. NH 3 is also produced when purifying NO X in the NO X storage catalyst 15.

ＮＯX選択還元触媒１３は、排気中のＮＯXをＮＨ3と反応させることにより、ＮＯXをＮ2に還元する。具体的に、ＮＯX選択還元触媒１３は、ＮＯX吸蔵触媒１５で生成されたＮＨ3を吸着し、流入する排気中のＮＯXをＮＨ3によってＮ2へと還元する。ＮＯX選択還元触媒１３は、触媒温度が高いほどＮＨ3の吸着可能量が減少する特性を有する。また、ＮＯX選択還元触媒１３は、ＮＨ3吸着量が多いほどＮＯXの還元効率が高くなる特性を有する。 The NO X selective reducing catalyst 13, by reacting the NO X in the exhaust and NH 3, to reduce the NO X to N 2. Specifically, the NO X selective reduction catalyst 13 adsorbs NH 3 generated in the NO X storage catalyst 15, and reduces NO X in the inflowing exhaust gas to N 2 by NH 3 . The NO X selective reduction catalyst 13 has a characteristic that the adsorbable amount of NH 3 decreases as the catalyst temperature increases. Further, the NO X selective reduction catalyst 13 has a characteristic that the NO X reduction efficiency increases as the NH 3 adsorption amount increases.

ＮＯX濃度センサ２３は、ＮＯX選択還元触媒１３よりも下流の排気管１１に設けられ、主としてＮＯX選択還元触媒１３から流出する排気中のＮＯX濃度を検出するために用いられる。ＮＯX濃度センサ２３のセンサ信号S_noxは、制御装置１００に送信される。ＮＯX濃度センサ２３のセンサ信号S_noxの情報は、ＮＯX選択還元触媒１３の異常診断に用いられる。 NO X concentration sensor 23, than the NO X selective reducing catalyst 13 disposed downstream of the exhaust pipe 11 is used to detect the concentration of NO X in the exhaust gas mainly flows out from the NO X selective reducing catalyst 13. The sensor signal S_nox of the NO X concentration sensor 23 is transmitted to the control device 100. The information on the sensor signal S_nox of the NO X concentration sensor 23 is used for the abnormality diagnosis of the NO X selective reduction catalyst 13.

ＮＯX濃度センサ２３は、ＮＯXだけでなくＮＨ3にも反応することが知られている。ただし、ＮＯX選択還元触媒１３が正常に機能している場合、ＮＯX選択還元触媒１３よりも下流側へのＮＨ3の流出はほぼゼロか極めて少量となる。このため、本実施形態に係る排気浄化装置１０では、ＮＯX濃度センサ２３のセンサ信号S_noxは基本的に排気ガス中のＮＯX濃度を示すものとして構築されている。 It is known that the NO X concentration sensor 23 reacts not only to NO X but also to NH 3 . However, when the NO X selective reduction catalyst 13 is functioning normally, the outflow of NH 3 to the downstream side of the NO X selective reduction catalyst 13 is almost zero or very small. Therefore, in the exhaust emission control device 10 according to the present embodiment, the sensor signal S_nox of the NO X concentration sensor 23 is basically constructed to indicate the NO X concentration in the exhaust gas.

この他、排気管１１の適宜の位置に、排気温度を検出する一つ又は複数の排気温度センサが備えられていてもよい。排気温度センサのセンサ信号S_tgは制御装置１００に送信される。排気温度センサが設けられた位置での排気温度の情報は、ＮＯX吸蔵触媒１５又はＮＯX選択還元触媒１３の温度の推定に用いることができる。 In addition, one or more exhaust gas temperature sensors that detect the exhaust gas temperature may be provided at an appropriate position of the exhaust pipe 11. The sensor signal S_tg of the exhaust temperature sensor is transmitted to the control device 100. The information on the exhaust temperature at the position where the exhaust temperature sensor is provided can be used for estimating the temperature of the NO X storage catalyst 15 or the NO X selective reduction catalyst 13.

＜２．診断装置（制御装置）＞
次に、本実施形態に係る診断装置として機能する制御装置１００の構成例について説明する。図２は、制御装置１００の構成例を示すブロック図である。図示した制御装置１００は、内燃機関５の運転状態を制御する制御装置１００である。なお、制御装置１００は、１つの制御装置から構成されていてもよく、あるいは、複数の制御装置が互いに通信可能に接続されて構成されていてもよい。 <2. Diagnostic device (control device)>
Next, a configuration example of the control device 100 that functions as the diagnostic device according to the present embodiment will be described. FIG. 2 is a block diagram showing a configuration example of the control device 100. The illustrated control device 100 is a control device 100 that controls the operating state of the internal combustion engine 5. It should be noted that the control device 100 may be configured by one control device, or may be configured by a plurality of control devices being communicably connected to each other.

制御装置１００はそれぞれＣＰＵ（Central Processing Unit）又はＭＰＵ（Micro Processing Unit）等のプロセッサと電気回路等を備えて構成され、プロセッサがコンピュータプログラムを実行することにより種々の機能が実現される装置であってよい。なお、制御装置１００の一部又は全部は、例えば、マイクロコンピュータ、マイクロプロセッサユニット等で構成されていてもよく、また、ファームウェア等の更新可能なもので構成されていてもよく、また、ＣＰＵ等からの指令によって実行されるプログラムモジュール等であってもよい。 The control device 100 includes a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), an electric circuit, and the like, and is a device that realizes various functions by executing a computer program by the processor. You can Note that part or all of the control device 100 may be configured by, for example, a microcomputer, a microprocessor unit, or the like, or may be configured by an updatable device such as firmware, or a CPU or the like. It may be a program module or the like executed by a command from.

制御装置１００は、上流側ＮＯX濃度取得部１１２と、上流側アンモニア濃度推定部１１３と、下流側ＮＯX濃度推定部１１４と、センサ値検出部１１６と、判定部１１８とを備えている。これらの各部は、プロセッサによるコンピュータプログラムの実行により実現される機能であってよい。また、制御装置１００は、ＲＡＭ（Random Access Memory）又はＲＯＭ（Read Only Memory）等の１つ又は複数の記憶素子を含む図示しない記憶部を備えている。記憶部は、プロセッサにより実行されるコンピュータプログラム、演算に用いられる制御パラメータ、プロセッサによる演算結果、及び取得したセンサ値等を記憶する。記憶部は、ＨＤＤ（Hard Disk Drive）やストレージ装置等を含んでいてもよい。 The control device 100 includes an upstream NO X concentration acquisition unit 112, an upstream ammonia concentration estimation unit 113, a downstream NO X concentration estimation unit 114, a sensor value detection unit 116, and a determination unit 118. Each of these units may be a function realized by execution of a computer program by a processor. The control device 100 also includes a storage unit (not shown) including one or more storage elements such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The storage unit stores a computer program executed by the processor, control parameters used for calculation, a calculation result by the processor, an acquired sensor value, and the like. The storage unit may include an HDD (Hard Disk Drive), a storage device, or the like.

（上流側ＮＯX濃度取得部）
上流側ＮＯX濃度取得部１１２は、ＮＯX吸蔵触媒１５よりも下流側、かつ、ＮＯX選択還元触媒１３よりも上流側の排気通路内のＮＯX濃度の推定値（上流側ＮＯX濃度推定値）N_us_modを算出する。ＮＯX選択還元触媒１３よりも上流側の排気に含まれるＮＯXは、ＮＯX吸蔵触媒１５において浄化されずに流出したＮＯXである。 (Upstream NO X concentration acquisition unit)
The upstream NO X concentration acquisition unit 112 estimates the NO X concentration in the exhaust passage downstream of the NO X storage catalyst 15 and upstream of the NO X selective reduction catalyst 13 (upstream NO X concentration estimation). Value) Calculate N_us_mod. NO X contained in the exhaust upstream of the the NO X selective reducing catalyst 13 is the NO X flowing out without being purified in the NO X storing catalyst 15.

ＮＯXの変換効率は、ＮＯX吸蔵触媒１５の温度や排気ガスの状態によって変動し得る。このため、上流側ＮＯX濃度取得部１１２は、例えばあらかじめ記憶部に格納されたマップを参照し、ＮＯX吸蔵触媒１５の温度や内燃機関５の運転条件に基づいて、計算に用いるＮＯX吸蔵触媒１５におけるＮＯXの変換効率を設定する。ＮＯX吸蔵触媒１５の温度は、例えば排気温度に基づいて推定することができる。 The NO X conversion efficiency may vary depending on the temperature of the NO X storage catalyst 15 and the state of exhaust gas. Therefore, the upstream NO X concentration acquisition unit 112 refers to, for example, a map stored in advance in the storage unit, and based on the temperature of the NO X storage catalyst 15 and the operating conditions of the internal combustion engine 5, the NO X storage used for calculation. The conversion efficiency of NO X in the catalyst 15 is set. The temperature of the NO X storage catalyst 15 can be estimated based on, for example, the exhaust temperature.

具体的に、上流側ＮＯX濃度取得部１１２は、ＮＯX吸蔵触媒１５の温度、内燃機関５が燃料リッチ状態に切り換えられたときのＮＯX吸蔵触媒１５におけるＮＯX吸蔵量、内燃機関５の燃料リッチ状態でのリッチ度合（空燃比）、及び内燃機関５のリッチ燃焼時間等の情報に基づいて上流側ＮＯX濃度N_us_modを算出する。内燃機関５の燃料リッチ状態におけるＮＯX吸蔵量、リッチ度合、及びリッチ燃焼時間は、内燃機関５の運転条件に基づいて推定することができる。 Specifically, the upstream-side NO X concentration acquiring unit 112, the temperature of the NO X storing catalyst 15, the NO X storage amount in the NO X storing catalyst 15 when the engine 5 is switched to the fuel-rich state, the internal combustion engine 5 The upstream NO X concentration N_us_mod is calculated based on the rich degree (air-fuel ratio) in the fuel rich state, the rich combustion time of the internal combustion engine 5, and the like. The NO X storage amount, the rich degree, and the rich combustion time in the fuel rich state of the internal combustion engine 5 can be estimated based on the operating conditions of the internal combustion engine 5.

なお、ＮＯX吸蔵触媒１５よりも下流側、かつ、ＮＯX選択還元触媒１３よりも上流側の排気通路内のＮＯX濃度を検出するＮＯX濃度センサを備える場合、上流側ＮＯX濃度取得部１１２は、当該ＮＯX濃度センサのセンサ信号に基づいて上流側ＮＯX濃度N_us_modを取得してもよい。 Incidentally, the downstream side of the NO X storing catalyst 15, and, if provided with a NO X concentration sensor than the NO X selective reducing catalyst 13 for detecting the concentration of NO X exhaust passage upstream of the upstream-side NO X concentration acquisition unit The 112 may acquire the upstream NO X concentration N_us_mod based on the sensor signal of the NO X concentration sensor.

（上流側アンモニア濃度推定部）
上流側アンモニア濃度推定部１１３は、ＮＯX吸蔵触媒１５よりも下流側、かつ、ＮＯX選択還元触媒１３よりも上流側の排気通路内のＮＨ3濃度の推定値（上流側ＮＨ3濃度推定値）NH3_us_modを算出する。 (Upstream ammonia concentration estimation unit)
The upstream side ammonia concentration estimation unit 113 estimates the NH 3 concentration in the exhaust passage downstream of the NO X storage catalyst 15 and upstream of the NO X selective reduction catalyst 13 (upstream NH 3 concentration estimation value). ) Calculate NH 3 _us_mod.

ＮＯX選択還元触媒１３よりも上流側の排気に含まれるＮＨ3は、ＮＯX吸蔵触媒１５において生成されたＮＨ3である。ＮＯX吸蔵触媒１５では、下記反応式（１）にしたがってＮＨ3が生成される。
３．５Ｈ2＋ＮＯ2→ＮＨ3＋２Ｈ2Ｏ … （１） NH contained in the upstream side exhaust than the NO X selective reducing catalyst 13 3 is NH 3 produced in the NO X storing catalyst 15. In the NO X storage catalyst 15, NH 3 is produced according to the following reaction formula (1).
3.5H 2 +NO 2 →NH 3 +2H 2 O (1)

例えば、上流側アンモニア濃度推定部１１３は、ＮＯX吸蔵触媒１５の温度、内燃機関５がリッチ燃焼状態に切り換えられたときのＮＯX吸蔵量、内燃機関５のリッチ燃焼状態でのリッチ度合（空燃比）及び内燃機関５のリッチ燃焼時間等の情報に基づいて上流側ＮＨ3濃度NH3_us_modを算出する。ＮＯX吸蔵触媒１５の温度は、例えば排気温度に基づいて推定することができる。内燃機関５のリッチ燃焼状態におけるＮＯX吸蔵量、リッチ度合、及びリッチ燃焼時間は、例えば内燃機関５の運転条件に基づいて推定することができる。 For example, the upstream side ammonia concentration estimation unit 113 uses the temperature of the NO X storage catalyst 15, the NO X storage amount when the internal combustion engine 5 is switched to the rich combustion state, the rich degree of the internal combustion engine 5 in the rich combustion state (empty). The upstream NH 3 concentration NH 3 _us_mod is calculated based on information such as the fuel ratio) and the rich combustion time of the internal combustion engine 5. The temperature of the NO X storage catalyst 15 can be estimated based on, for example, the exhaust temperature. The NO X storage amount, the rich degree, and the rich combustion time in the rich combustion state of the internal combustion engine 5 can be estimated based on the operating conditions of the internal combustion engine 5, for example.

なお、ＮＯX吸蔵触媒１５よりも下流側、かつ、ＮＯX選択還元触媒１３よりも上流側の排気通路内のＮＨ3濃度を検出するアンモニア濃度センサを備える場合、上流側アンモニア濃度推定部１１３は、当該アンモニア濃度センサのセンサ信号に基づいて上流側ＮＨ3濃度NH3_us_modを取得してもよい。 When the ammonia concentration sensor for detecting the NH 3 concentration in the exhaust passage downstream of the NO X storage catalyst 15 and upstream of the NO X selective reduction catalyst 13 is provided, the upstream ammonia concentration estimation unit 113 The upstream NH 3 concentration NH 3 _us_mod may be acquired based on the sensor signal of the ammonia concentration sensor.

（下流側ＮＯX濃度推定部）
下流側ＮＯX濃度推定部１１４は、ＮＯX選択還元触媒１３よりも下流側の排気通路内のＮＯX濃度の推定値（下流側ＮＯX濃度推定値）N_ds_modを算出する。ＮＯX選択還元触媒１３よりも下流側の排気に含まれるＮＯXは、ＮＯX吸蔵触媒１５で浄化されずに流出したＮＯXのうち、さらにＮＯX選択還元触媒１３においても還元されずに流出したＮＯXである。ＮＯX選択還元触媒１３が正常に機能している場合、ＮＯX選択還元触媒１３から流出するＮＯXは極僅かである。このため、下流側ＮＯX濃度推定値N_ds_modは比較的小さい値となる。 (Downstream NO X concentration estimation unit)
The downstream NO X concentration estimation unit 114 calculates an estimated value of NO X concentration in the exhaust passage downstream of the NO X selective reduction catalyst 13 (downstream NO X concentration estimated value) N_ds_mod. NO X contained in the exhaust downstream of the NO X selective reducing catalyst 13, out of the NO X flowing out without being purified in the NO X storing catalyst 15, flows out without further also reduced in the NO X selective reducing catalyst 13 It is NO x . If the NO X selective reducing catalyst 13 is functioning properly, NO X flowing out from the NO X selective reducing catalyst 13 is negligible. Therefore, the downstream side NO x concentration estimated value N_ds_mod becomes a relatively small value.

上述のとおり、ＮＯX選択還元触媒１３におけるＮＨ3の最大吸着量は、ＮＯX選択還元触媒１３の温度が高いほど減少する。また、ＮＯX選択還元触媒１３におけるＮＯXの還元効率は、上記吸着率が高いほど高くなる。このため、下流側ＮＯX濃度推定部１１４は、例えばあらかじめ記憶部に格納されたマップを参照し、ＮＯX選択還元触媒１３の温度やＮＨ3の吸着率に基づいて、計算に用いるＮＯX選択還元触媒１３におけるＮＯXの還元効率を設定する。ＮＯX選択還元触媒１３の温度は、例えば排気温度に基づいて推定することができる。ＮＨ3の吸着率は、上流側ＮＯX濃度N_us_mod、上流側ＮＨ3濃度NH3_us_mod、排気流量及びＮＯX選択還元触媒１３の温度に基づいて推定することができる。 As described above, the maximum amount of adsorption of NH 3 in the NO X selective reducing catalyst 13, the temperature of the NO X selective reducing catalyst 13 is reduced the higher. Further, the reduction efficiency of the NO X in the NO X selective reducing catalyst 13 becomes higher as the adsorption rate is high. Therefore, the downstream NO X concentration estimation unit 114 refers to, for example, a map stored in advance in the storage unit, and based on the temperature of the NO X selective reduction catalyst 13 and the adsorption rate of NH 3 , the NO X selection used for the calculation. The reduction efficiency of NO x in the reduction catalyst 13 is set. The temperature of the NO X selective reduction catalyst 13 can be estimated based on, for example, the exhaust temperature. Adsorption rate of NH 3 can be estimated based upstream NO X concentration N_us_mod, upstream NH 3 concentration NH 3 _Us_mod, the temperature of the exhaust gas flow and the NO X selective reducing catalyst 13.

ＮＨ3の吸着率は、例えば以下のように推定することができる。
ＮＯX選択還元触媒１３では、下記反応式（２）にしたがってＮＯXの還元反応が生じる。
４ＮＨ3＋３ＮＯ2→３．５Ｎ2＋６Ｈ2Ｏ … （２）
下流側ＮＯX濃度推定部１１４は、ＮＯX選択還元触媒１３に流入するＮＯX量及びＮＨ3量と、ＮＯX選択還元触媒１３の温度とを用いてＮＯX選択還元触媒１３におけるＮＨ3の吸着量を算出することができる。 The NH 3 adsorption rate can be estimated as follows, for example.
In the NO X selective reduction catalyst 13, a NO X reduction reaction occurs according to the following reaction formula (2).
4NH 3 +3NO 2 →3.5N 2 +6H 2 O (2)
Downstream NO X density estimating unit 114, and the amount of NO X and NH 3 amount flowing into the NO X selective reducing catalyst 13, the NH 3 in the NO X selective reducing catalyst 13 by using the temperature of the NO X selective reducing catalyst 13 The amount of adsorption can be calculated.

ＮＯX選択還元触媒に流入するＮＯX量及びＮＨ3量は、それぞれ上流側ＮＯX濃度N_us_mod及び上流側アンモニア濃度NH3_usに排気流量をかけることで求めることができる。下流側ＮＯX濃度推定部１１４は、所定の演算サイクルごとに、各演算サイクル中にＮＯX選択還元触媒１３に流入するＮＯX量及びＮＨ3量を算出する。そして、下流側ＮＯX濃度推定部１１４は、算出したＮＯX量のＮＯXを還元するために必要なＮＨ3量を、算出したＮＨ3量から引き、得られた値を演算サイクルごとに積算し続ける。これにより、下流側ＮＯX濃度推定部１１４は、ＮＯX選択還元触媒１３におけるＮＨ3の吸着量の変化を見ることができる。 The amount of NO X and NH 3 amount flowing into the NO X selective reducing catalyst can be determined by the upstream NO X concentration N_us_mod and upstream the ammonia concentration NH 3 _us respectively applying an exhaust flow rate. Downstream NO X density estimating unit 114, for each predetermined calculation cycle to calculate the amount of NO X and NH 3 amount flowing into the NO X selective reducing catalyst 13 during each operation cycle. Then, the downstream NO X density estimating unit 114 integrates the NH 3 amount required for reducing the NO X of the calculated amount of NO X, subtracted from the calculated NH 3 amount, the resulting value for each calculation cycle Keep doing As a result, the downstream NO X concentration estimating unit 114 can see the change in the amount of adsorbed NH 3 in the NO X selective reduction catalyst 13.

このようにしてＮＨ3の吸着量が算出されると、ＮＯX選択還元触媒１３の温度に応じた最大吸着量に対するＮＨ3の吸着率が求められる。下流側ＮＯX濃度推定部１１４は、ＮＨ3の吸着率に応じたＮＯX選択還元触媒１３におけるＮＯXの還元効率を上流側ＮＯX濃度N_us_modにかけることで、下流側ＮＯX濃度推定値N_ds_modを算出することができる。 When the adsorption amount of NH 3 is calculated in this way, the adsorption ratio of NH 3 with respect to the maximum adsorption amount according to the temperature of the NO X selective reduction catalyst 13 is obtained. Downstream NO X density estimating unit 114, by multiplying the reduction efficiency of the NO X in the NO X selective reducing catalyst 13 in accordance with the adsorption rate of NH 3 upstream NO X concentration N_us_mod, downstream NO X concentration estimated value N_ds_mod Can be calculated.

（センサ値検出部）
センサ値検出部１１６は、ＮＯX濃度センサ２３のセンサ信号S_noxに基づいて、センサ値としての下流側ＮＯX濃度（下流側ＮＯX濃度検出値）N_ds_detを検出する。この下流側ＮＯX濃度検出値N_ds_detは、基本的にはＮＯX濃度の値を示すが、ＮＯX選択還元触媒１３の下流側にＮＨ3が流出している状態ではＮＨ3濃度の値を示すことになる。 (Sensor value detector)
The sensor value detection unit 116 detects the downstream NO X concentration (downstream NO X concentration detection value) N_ds_det as the sensor value based on the sensor signal S_nox of the NO X concentration sensor 23. The downstream NO x concentration detection value N_ds_det basically indicates the value of the NO x concentration, but indicates the value of the NH 3 concentration when NH 3 is flowing out to the downstream side of the NO x selective reduction catalyst 13. It will be.

（判定部）
判定部１１８は、少なくとも下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detに基づいてＮＯX選択還元触媒１３の異常を判定する。本実施形態では、判定部１１８は、上流側ＮＯX濃度N_us_mod、上流側ＮＨ3濃度NH3_us_mod、下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detに基づいて、ＮＯX選択還元触媒１３の欠落及び劣化を判定する。 (Judgment part)
The determination unit 118 determines the abnormality of the NO X selective reduction catalyst 13 based on at least the downstream NO X concentration estimated value N_ds_mod and the downstream NO X concentration detected value N_ds_det. In the present embodiment, the judgment unit 118, the upstream-side NO X concentration N_us_mod, upstream NH 3 concentration NH 3 _Us_mod, on the basis of the downstream-side NO X concentration estimated value N_ds_mod and downstream NO X concentration detected value N_ds_det, NO X selective The reduction catalyst 13 is determined to be missing or deteriorated.

ＮＯX選択還元触媒１３に欠落や劣化等の異常がない場合、ＮＯX濃度センサ２３のセンサ信号S_noxに基づいて得られる下流側ＮＯX濃度検出値N_ds_detは、下流側ＮＯX濃度推定部１１４で推定される下流側ＮＯX濃度推定値N_ds_modに近似する。一方、ＮＯX選択還元触媒１３に欠落や劣化等の異常が生じている場合、ＮＯX選択還元触媒１３におけるＮＨ3の最大吸着量は減少するために、ＮＯX選択還元触媒１３の下流側へのＮＨ3の流出量が増加する。 When the NO X selective reduction catalyst 13 has no abnormality such as missing or deterioration, the downstream NO X concentration detection value N_ds_det obtained based on the sensor signal S_nox of the NO X concentration sensor 23 is obtained by the downstream NO X concentration estimating unit 114. It is approximated to the estimated downstream NO x concentration estimated value N_ds_mod. On the other hand, if there is an abnormality such as missing or degraded to the NO X selective reducing catalyst 13, for maximum adsorption amount of NH 3 in the NO X selective reducing catalyst 13 to decrease, to the downstream side of the NO X selective reducing catalyst 13 Outflow of NH 3 increases.

このため、ＮＯX選択還元触媒１３の異常時において、ＮＯX濃度センサ２３を用いて検出される下流側ＮＯX濃度検出値N_ds_detは、下流側ＮＯX濃度推定値N_ds_modよりも大きい値となる。このような現象を利用して、判定部１１８は、下流側ＮＯX濃度検出値N_ds_detと下流側ＮＯX濃度推定値N_ds_modとを比較することにより、ＮＯX選択還元触媒１３の異常の有無を判定することができる。 Therefore, when the NO X selective reduction catalyst 13 is abnormal, the downstream NO X concentration detection value N_ds_det detected using the NO X concentration sensor 23 becomes a value larger than the downstream NO X concentration estimated value N_ds_mod. Utilizing such a phenomenon, the determination unit 118 determines whether or not there is an abnormality in the NO X selective reduction catalyst 13 by comparing the downstream NO X concentration detection value N_ds_det with the downstream NO X concentration estimated value N_ds_mod. can do.

また、ＮＯX選択還元触媒１３が欠落している場合と劣化している場合とでは、下流側ＮＯX濃度検出値N_ds_detの値に差が生じる。本実施形態において、判定部１１８は、ＮＯX選択還元触媒１３の劣化又は欠落を判別する。具体的に、ＮＯX選択還元触媒１３が欠落している場合、ＮＯX選択還元触媒１３に吸着されるＮＨ3の量はゼロであり、すべてのＮＨ3がＮＯX濃度センサ２３の設置位置に到達する。一方、ＮＯX選択還元触媒１３が劣化している場合、ＮＯX選択還元触媒１３に流入するＮＨ3の一部はＮＯX選択還元触媒１３に吸着され、又はＮＯXの還元反応に用いられる。 Further, there is a difference in the downstream side NO X concentration detection value N_ds_det when the NO X selective reduction catalyst 13 is missing and when it is deteriorated. In the present embodiment, the determination unit 118 determines whether the NO X selective reduction catalyst 13 has deteriorated or is missing. Specifically, when the NO X selective reduction catalyst 13 is missing, the amount of NH 3 adsorbed on the NO X selective reduction catalyst 13 is zero, and all NH 3 is in the installation position of the NO X concentration sensor 23. To reach. On the other hand, if the NO X selective reducing catalyst 13 is deteriorated, a part of the NH 3 flowing into the NO X selective reducing catalyst 13 is adsorbed on the NO X selective reducing catalyst 13, or used for the reduction reaction of NO X.

したがって、ＮＯX選択還元触媒１３の欠落時にＮＯX濃度センサ２３を用いて検出される下流側ＮＯX濃度検出値N_ds_detは、ＮＯX選択還元触媒１３の劣化時に検出される下流側ＮＯX濃度検出値N_ds_detに比べて大きい値になる。判定部１１８は、ＮＯX選択還元触媒１３の異常時に、下流側ＮＯX濃度推定値N_ds_modに対する下流側ＮＯX濃度検出値N_ds_detのずれ幅に基づいて、ＮＯX選択還元触媒１３の欠落又は劣化を判定することができる。 Thus, the downstream NO X concentration detected value N_ds_det detected using the NO X concentration sensor 23 at the time of lack of the NO X selective reducing catalyst 13, the downstream-side NO X concentration detected encountered during the degradation of the NO X selective reducing catalyst 13 The value is larger than the value N_ds_det. When the NO X selective reduction catalyst 13 is abnormal, the determination unit 118 determines whether the NO X selective reduction catalyst 13 is missing or deteriorated based on the deviation width of the downstream NO X concentration detection value N_ds_det with respect to the downstream NO X concentration estimated value N_ds_mod. Can be judged.

このとき判定部１１８は、所定期間における下流側ＮＯX濃度検出値N_ds_detの積算値と、下流側ＮＯX濃度推定値N_ds_modの積算値とを比較してもよい。それぞれの積算値を比較することにより、下流側ＮＯX濃度検出値N_ds_detと、下流側ＮＯX濃度推定値N_ds_modとのずれ幅がより判別しやすくなる。 At this time, the determination unit 118 may compare the integrated value of the downstream NO X concentration detected value N_ds_det and the integrated value of the downstream NO X concentration estimated value N_ds_mod in the predetermined period. By comparing the respective integrated values, the difference between the downstream NO X concentration detection value N_ds_det and the downstream NO X concentration estimated value N_ds_mod becomes easier to discriminate.

図３は、ＮＯX選択還元触媒１３の正常時、欠落時、及び劣化時における下流側ＮＯX濃度検出値N_ds_detの違いを示す説明図である。図３は、時刻ｔ１から時刻ｔ２までの期間における下流側ＮＯX濃度検出値N_ds_det及び下流側ＮＯX濃度推定値N_ds_modの積算値の例を示している。 FIG. 3 is an explanatory diagram showing a difference in the downstream NO X concentration detection value N_ds_det when the NO X selective reduction catalyst 13 is normal, when it is missing, and when it is deteriorated. FIG. 3 shows an example of the integrated value of the downstream NO X concentration detection value N_ds_det and the downstream NO X concentration estimated value N_ds_mod in the period from time t1 to time t2.

ＮＯX選択還元触媒１３が正常に機能している場合、下流側ＮＯX濃度検出値N_ds_detは下流側ＮＯX濃度推定値NH3_ds_modに近似する。このため、ＮＯX選択還元触媒１３の正常時において、下流側ＮＯX濃度検出値N_ds_detの積算値は、下流側ＮＯX濃度推定値N_ds_modの積算値とほぼ同じように推移する。 When the NO X selective reduction catalyst 13 is functioning normally, the downstream NO X concentration detection value N_ds_det approximates the downstream NO X concentration estimated value NH 3 _ds_mod. Therefore, when the NO X selective reduction catalyst 13 is normal, the integrated value of the downstream NO X concentration detection value N_ds_det changes substantially in the same manner as the integrated value of the downstream NO X concentration estimated value N_ds_mod.

一方、ＮＯX選択還元触媒１３が欠落している場合、ＮＯX吸蔵触媒１５で生成されたＮＨ3がＮＯX濃度センサ２３により検出されるため、下流側ＮＯX濃度検出値N_ds_detは、下流側ＮＯX濃度推定値N_ds_modに比べて大きい値になる。このため、ＮＯX選択還元触媒１３の欠落時において、下流側ＮＯX濃度検出値N_ds_detの積算値は、下流側ＮＯX濃度推定値N_ds_modの積算値を大きく上回りながら推移する。 On the other hand, when the NO X selective reduction catalyst 13 is missing, NH 3 generated in the NO X storage catalyst 15 is detected by the NO X concentration sensor 23, so the downstream NO X concentration detection value N_ds_det is The value is larger than the NO X concentration estimated value N_ds_mod. Therefore, when the NO X selective reduction catalyst 13 is missing, the integrated value of the downstream NO X concentration detection value N_ds_det changes while greatly exceeding the integrated value of the downstream NO X concentration estimated value N_ds_mod.

また、ＮＯX選択還元触媒１３が劣化している場合、ＮＯX吸蔵触媒１５で生成されたＮＨ3の一部がＮＯX選択還元触媒１３の下流側に流出するために、下流側ＮＯX濃度検出値N_ds_detは、下流側ＮＯX濃度推定値N_ds_modに比べて大きい値になる。ただし、このときの下流側ＮＯX濃度検出値N_ds_detは、ＮＯX選択還元触媒１３の欠落時の値に比べて小さい値になる。このため、ＮＯX選択還元触媒１３の劣化時において、下流側ＮＯX濃度検出値N_ds_detの積算値は、ＮＯX選択還元触媒１３の正常時の積算値と欠落時の積算値との間を推移する。 Further, when the NO X selective reduction catalyst 13 is deteriorated, a part of NH 3 generated in the NO X storage catalyst 15 flows out to the downstream side of the NO X selective reduction catalyst 13, so that the NO X concentration on the downstream side is reduced. The detected value N_ds_det becomes a larger value than the downstream side NO X concentration estimated value N_ds_mod. However, the downstream NO X concentration detection value N_ds_det at this time becomes a value smaller than the value when the NO X selective reduction catalyst 13 is missing. Therefore, when the NO X selective reduction catalyst 13 deteriorates, the integrated value of the downstream NO X concentration detection value N_ds_det changes between the integrated value when the NO X selective reduction catalyst 13 is normal and the integrated value when the NO X selective reduction catalyst 13 is missing. To do.

このように、判定部１１８は、時刻ｔ２における下流側ＮＯX濃度検出値N_ds_detの積算値と下流側ＮＯX濃度推定値N_ds_modの積算値との差が小さい場合には、ＮＯX選択還元触媒１３が正常に機能していると判定することができる。また、時刻ｔ２における下流側ＮＯX濃度検出値N_ds_detの積算値と下流側ＮＯX濃度推定値N_ds_modの積算値との差が大きい場合には、判定部１１８は、ＮＯX選択還元触媒１３が異常であると判定する。 As described above, when the difference between the integrated value of the downstream NO X concentration detection value N_ds_det and the integrated value of the downstream NO X concentration estimated value N_ds_mod at time t2 is small, the determination unit 118 determines that the NO X selective reduction catalyst 13 Can be determined to be functioning normally. When the difference between the integrated value of the downstream NO X concentration detection value N_ds_det and the integrated value of the downstream NO X concentration estimated value N_ds_mod at time t2 is large, the determination unit 118 determines that the NO X selective reduction catalyst 13 is abnormal. Is determined.

さらに、判定部１１８は、例えば時刻ｔ２における下流側ＮＯX濃度推定値N_ds_modの積算値（Ｘ）に対する下流側ＮＯX濃度検出値N_ds_detの積算値（Ｙ）の比（Ｙ／Ｘ）が、あらかじめ設定した閾値βを超える場合に、ＮＯX選択還元触媒１３が欠落していると判定してもよい。閾値βは、例えば、下流側ＮＯX濃度推定値N_ds_modの積算値（Ｘ）に対する上流側ＮＨ3濃度推定値NH3_us_modの積算値（Ｚ）の比（Ｚ／Ｘ）とすることができる。 Further, the determination unit 118 determines in advance, for example, that the ratio (Y/X) of the integrated value (Y) of the downstream side NO X concentration detected value N_ds_det to the integrated value (X) of the downstream side NO X concentration estimated value N_ds_mod at time t2. When the set threshold value β is exceeded, it may be determined that the NO X selective reduction catalyst 13 is missing. The threshold β can be, for example, a ratio (Z/X) of the integrated value (Z) of the upstream side NH 3 concentration estimated value NH 3 _us_mod to the integrated value (X) of the downstream side NO x concentration estimated value N_ds_mod.

ＮＯX選択還元触媒１３が欠落している場合、ＮＯX濃度センサ２３の設置位置には、ＮＯX吸蔵触媒１５で生成されたＮＨ3と併せてＮＯX吸蔵触媒１５から流出したＮＯXが到達する。このため、ＮＯX選択還元触媒１３の欠落時のＮＯX濃度センサ２３の検出値（下流側ＮＯX濃度検出値N_ds_mod）は、少なくとも上流側ＮＨ3濃度推定値NH3_us_modを上回る。したがって、閾値βを、下流側ＮＯX濃度推定値N_ds_modの積算値（Ｘ）に対する上流側ＮＨ3濃度推定値NH3_us_modの積算値（Ｚ）の比（Ｚ／Ｘ）とすることで、ＮＯX選択還元触媒１３の欠落を判別することができる。 If the NO X selective reducing catalyst 13 is missing, NO X in the installation position of the density sensor 23, NO X storing catalyst 15 together with NH 3 produced by the NO X NO X flowing out from storing catalyst 15 reaches To do. Therefore, the detection value of the NO X concentration sensor 23 (downstream NO X concentration detection value N_ds_mod) when the NO X selective reduction catalyst 13 is missing exceeds at least the upstream NH 3 concentration estimated value NH 3 _us_mod. Therefore, by setting the threshold value β to the ratio (Z/X) of the integrated value (Z) of the upstream side NH 3 concentration estimated value NH 3 _us_mod to the integrated value (X) of the downstream side NO x concentration estimated value N_ds_mod, NO The lack of the X selective reduction catalyst 13 can be determined.

ＮＯX選択還元触媒１３の欠落時には、ＮＯX選択還元触媒１３が意図的に除去されていることも考えられるため、判定部１１８は、例えば内燃機関５を強制的に停止させる処置を取るようにしてもよい。また、ＮＯX選択還元触媒１３の劣化時には、判定部１１８は、例えば警告ランプを点灯させたり警報を鳴らしたりすることで、運転者等にＮＯX選択還元触媒１３の交換を促すようにしてもよい。 When the NO X selective reduction catalyst 13 is missing, it is possible that the NO X selective reduction catalyst 13 has been intentionally removed. Therefore, the determination unit 118 should take measures to forcibly stop the internal combustion engine 5, for example. May be. Further, when the NO X selective reduction catalyst 13 is deteriorated, the determination unit 118 may urge the driver or the like to replace the NO X selective reduction catalyst 13, for example, by turning on a warning lamp or sounding an alarm. Good.

＜３．診断装置の動作例＞
次に、図４のフローチャートを参照して、診断装置として機能する制御装置１００の動作例を説明する。 <3. Diagnostic device operation example>
Next, an operation example of the control device 100 functioning as a diagnostic device will be described with reference to the flowchart of FIG.

まず、制御装置１００の上流側アンモニア濃度推定部１１３、下流側ＮＯX濃度推定部１１４及びセンサ値検出部１１６は、上流側ＮＨ3濃度推定値NH3_us_mod、下流側ＮＯX濃度推定値N_ds_mod、及び下流側ＮＯX濃度検出値N_ds_detの積算を開始する（ステップＳ１１）。例えば、各部は、内燃機関５が燃料リーン状態から燃料リッチ状態に切り換えられたときに上記積算を開始してもよい。これにより、ＮＯX吸蔵触媒１５でＮＨ3が生成される期間を利用した診断を行うことができ、診断結果の信頼性を向上させることができる。 First, the upstream ammonia concentration estimation unit 113, the downstream NO X concentration estimation unit 114, and the sensor value detection unit 116 of the control device 100 include the upstream NH 3 concentration estimation value NH 3 _us_mod, the downstream NO X concentration estimation value N_ds_mod, Then, the integration of the downstream NO x concentration detection value N_ds_det is started (step S11). For example, each unit may start the integration when the internal combustion engine 5 is switched from the fuel lean state to the fuel rich state. As a result, it is possible to make a diagnosis using the period during which NH 3 is produced in the NO X storage catalyst 15, and it is possible to improve the reliability of the diagnosis result.

次いで、上流側アンモニア濃度推定部１１３及び下流側ＮＯX濃度推定部１１４は、それぞれ上流側ＮＨ3濃度推定値NH3_us_mod及び下流側ＮＯX濃度推定値N_ds_modを算出し、センサ値検出部１１６は下流側ＮＯX濃度検出値N_ds_detを検出する（ステップＳ１３）。 Next, the upstream side ammonia concentration estimation unit 113 and the downstream side NO X concentration estimation unit 114 calculate the upstream side NH 3 concentration estimated value NH 3 _us_mod and the downstream side NO X concentration estimated value N_ds_mod, respectively, and the sensor value detection unit 116 The downstream NO x concentration detection value N_ds_det is detected (step S13).

次いで、上流側アンモニア濃度推定部１１３、下流側ＮＯX濃度推定部１１４及びセンサ値検出部１１６は、それぞれステップＳ１３で得られた上流側ＮＨ3濃度推定値NH3_us_mod、下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detを積算する（ステップＳ１５）。 Next, the upstream side ammonia concentration estimation unit 113, the downstream side NO X concentration estimation unit 114 and the sensor value detection unit 116 respectively estimate the upstream side NH 3 concentration estimated value NH 3 _us_mod and the downstream side NO X concentration estimated in step S13. The value N_ds_mod and the downstream NO X concentration detection value N_ds_det are integrated (step S15).

次いで、上流側アンモニア濃度推定部１１３、下流側ＮＯX濃度推定部１１４及びセンサ値検出部１１６は、積算を開始してからの経過時間が、あらかじめ設定された所定時間を経過したか否かを判別する（ステップＳ１７）。所定時間は、診断結果の信頼性の許容範囲等を考慮して、適宜の時間に設定されてよい。 Next, the upstream side ammonia concentration estimation unit 113, the downstream side NO X concentration estimation unit 114 and the sensor value detection unit 116 determine whether or not the elapsed time from the start of integration has reached a preset predetermined time. It is determined (step S17). The predetermined time may be set to an appropriate time in consideration of the tolerance range of the reliability of the diagnosis result and the like.

経過時間が所定時間を経過していない場合（Ｓ１７／Ｎｏ）、上流側アンモニア濃度推定部１１３、下流側ＮＯX濃度推定部１１４及びセンサ値検出部１１６は、ステップＳ１３に戻って、上流側ＮＨ3濃度推定値NH3_us_mod、下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detの算出あるいは検出、及び積算を繰り返す。 If the elapsed time has not exceeded the predetermined time (S17 / No), upstream the ammonia concentration estimating unit 113, the downstream NO X density estimating unit 114 and the sensor value detection unit 116 returns to step S13, the upstream NH 3 Calculation or detection of the concentration estimated value NH 3 _us_mod, the downstream side NO X concentration estimated value N_ds_mod, and the downstream side NO X concentration detected value N_ds_det, and integration are repeated.

一方、経過時間が所定時間を経過した場合（Ｓ１７／Ｙｅｓ）、制御装置１００の判定部１１８は、下流側ＮＯX濃度検出値N_ds_detの積算値∫N_ds_detと下流側ＮＯX濃度推定値NH3_ds_modの積算値∫NH3_ds_modとの差が閾値αを超えているか否かを判別する（ステップＳ１９）。閾値αは、下流側ＮＯX濃度推定値N_ds_modの誤差や、積算を行う所定時間の長さ等を考慮して、適切な値に設定することができる。 On the other hand, when the elapsed time has passed the predetermined time (S17/Yes), the determination unit 118 of the control device 100 determines that the integrated value ∫N_ds_det of the downstream NO X concentration detection value N_ds_det and the downstream NO X concentration estimated value NH 3 _ds_mod. It is determined whether or not the difference between the integrated value ∫NH 3 _ds_mod and the threshold value α is exceeded (step S19). The threshold value α can be set to an appropriate value in consideration of the error of the downstream side NO X concentration estimated value N_ds_mod, the length of a predetermined time for performing the integration, and the like.

差｜∫N_ds_det−∫N_ds_mod｜が閾値α以下の場合（Ｓ１９／Ｎｏ）、判定部１１８は、ＮＯX選択還元触媒１３が正常に機能している（異常無し）と判定し（ステップＳ２７）、本ルーチンを終了する。一方、差｜∫N_ds_det−∫N_ds_mod｜が閾値αを超える場合（Ｓ１９／Ｙｅｓ）、判定部１１８は、下流側ＮＯX濃度推定値N_ds_modの積算値∫N_ds_modに対する下流側ＮＯX濃度検出値N_ds_detの積算値∫N_ds_detの比が閾値βを超えているか否かを判別する（ステップＳ２１）。閾値βは、例えば下流側ＮＯX濃度推定値N_ds_modの積算値∫N_ds_modに対する上流側ＮＨ3濃度推定値NH3_us_modの積算値∫NH3_us_modの比の値であってもよい。 When the difference |∫N_ds_det−∫N_ds_mod| is less than or equal to the threshold value α (S19/No), the determination unit 118 determines that the NO X selective reduction catalyst 13 is functioning normally (no abnormality) (step S27), This routine ends. On the other hand, when the difference |∫N_ds_det−∫N_ds_mod| exceeds the threshold value α (S19/Yes), the determination unit 118 determines the downstream NO X concentration detection value N_ds_det with respect to the integrated value ∫N_ds_mod of the downstream NO X concentration estimated value N_ds_mod. It is determined whether or not the ratio of the integrated value ∫N_ds_det exceeds the threshold β (step S21). The threshold value β may be, for example, a value of a ratio of the integrated value ∫NH 3 _us_mod of the upstream NH 3 concentration estimated value NH 3 _us_mod to the integrated value ∫N_ds_mod of the downstream NO x concentration estimated value N_ds_mod.

下流側ＮＯX濃度推定値N_ds_modの積算値∫N_ds_modに対する下流側ＮＯX濃度検出値N_ds_detの積算値∫N_ds_detの比が閾値βを超える場合（Ｓ２１／Ｙｅｓ）、判定部１１８は、ＮＯX選択還元触媒１３が欠落していると判定し（ステップＳ２３）、本ルーチンを終了する。一方、下流側ＮＯX濃度推定値N_ds_modの積算値∫N_ds_modに対する下流側ＮＯX濃度検出値N_ds_detの積算値∫N_us_detの比が閾値β以下の場合（Ｓ２１／Ｎｏ）、判定部１１８は、ＮＯX選択還元触媒１３が劣化していると判定し（ステップＳ２５）、本ルーチンを終了する。 When the ratio of the integrated value ∫N_ds_det of the downstream NO X concentration detection value N_ds_det to the integrated value ∫N_ds_mod of the downstream side NO X concentration estimated value N_ds_mod exceeds the threshold β (S21/Yes), the determination unit 118 causes the NO X selective reduction. It is determined that the catalyst 13 is missing (step S23), and this routine ends. On the other hand, when the ratio of the integrated value ∫N_us_det of the downstream NO X concentration detection value N_ds_det to the integrated value ∫N_ds_mod of the downstream side NO X concentration estimated value N_ds_mod is less than or equal to the threshold value β (S21/No), the determination unit 118 determines that NO X It is determined that the selective reduction catalyst 13 has deteriorated (step S25), and this routine ends.

以上説明したように、本実施形態に係る内燃機関５の排気浄化装置１０は、排気通路の上流側から順にＮＯX吸蔵触媒１５及びＮＯX選択還元触媒１３を備えるとともに、ＮＯX選択還元触媒１３よりも下流側にＮＯX濃度センサ２３を備えている。かかる排気浄化装置１０のＮＯX選択還元触媒１３の異常を診断する診断装置として機能する制御装置１００は、下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detに基づいてＮＯX選択還元触媒１３の異常の有無を判定する。したがって、制御装置１００は、ＮＯX選択還元触媒１３が正常に機能していない異常状態を検知することができる。 As described above, the exhaust purification system 10 for the internal combustion engine 5 according to the present embodiment includes the NO X storage catalyst 15 and the NO X selective reduction catalyst 13 in this order from the upstream side of the exhaust passage, and the NO X selective reduction catalyst 13 The NO x concentration sensor 23 is provided on the downstream side of the above. Controller 100 functioning as a diagnostic device for diagnosing an abnormality of the NO X selective reducing catalyst 13 such exhaust gas purification device 10, the NO X selective on the basis of the downstream-side NO X concentration estimated value N_ds_mod and downstream NO X concentration detected value N_ds_det Whether the reduction catalyst 13 is abnormal is determined. Therefore, the control device 100 can detect an abnormal state in which the NO X selective reduction catalyst 13 is not functioning normally.

また、本実施形態において、制御装置１００は、ＮＯX選択還元触媒１３の異常時に、さらに上流側ＮＨ3濃度推定値NH3_us_mod、下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detに基づいて、ＮＯX選択還元触媒１３の欠落又は劣化を判定する。したがって、制御装置１００は、ＮＯX選択還元触媒１３の異常の状態に応じた処理を実行することができる。 Further, in the present embodiment, when the NO X selective reduction catalyst 13 is abnormal, the control device 100 further causes the upstream side NH 3 concentration estimated value NH 3 _us_mod, the downstream side NO X concentration estimated value N_ds_mod, and the downstream side NO X concentration detected value. The lack or deterioration of the NO X selective reduction catalyst 13 is determined based on N_ds_det. Therefore, the control device 100 can execute the processing according to the abnormal state of the NO X selective reduction catalyst 13.

また、本実施形態において、制御装置１００は、上流側ＮＨ3濃度推定値NH3_us_modの積算値∫NH3_us_mod、下流側ＮＯX濃度推定値N_ds_modの積算値∫N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detの積算値∫N_ds_detを用いてＮＯX選択還元触媒１３の異常を判定する。したがって、下流側ＮＯX濃度検出値N_ds_detと、上流側ＮＨ3濃度推定値NH3_us_modあるいは下流側ＮＯX濃度推定値N_ds_modとの差をより判別しやすくなって、ＮＯX選択還元触媒１３の異常診断結果の信頼性を向上させることができる。 Further, in the present embodiment, the control device 100 detects the integrated value ∫NH 3 _us_mod of the upstream side NH 3 concentration estimated value NH 3 _us_mod, the integrated value ∫N_ds_mod of the downstream side NO X concentration estimated value N_ds_mod, and the downstream side NO X concentration detection. An abnormality of the NO X selective reduction catalyst 13 is determined using the integrated value ∫N_ds_det of the value N_ds_det. Therefore, the difference between the downstream NO x concentration detection value N_ds_det and the upstream side NH 3 concentration estimated value NH 3 _us_mod or the downstream side NO x concentration estimated value N_ds_mod can be more easily discriminated, and the abnormality of the NO x selective reduction catalyst 13 can be obtained. The reliability of the diagnosis result can be improved.

以上、添付図面を参照しながら本発明の好適な実施形態について詳細に説明したが、本発明はかかる例に限定されない。本発明の属する技術の分野における通常の知識を有する者であれば、特許請求の範囲に記載された技術的思想の範疇内において、各種の変更例または修正例に想到し得ることは明らかであり、これらについても、当然に本発明の技術的範囲に属するものと了解される。 The preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings, but the present invention is not limited to these examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

例えば上記実施形態において、上流側ＮＨ3濃度推定値NH3_us_mod、下流側ＮＯX濃度推定値N_ds_mod及び下流側ＮＯX濃度検出値N_ds_detの積算は、必ずしも連続する期間において行われなくてもよい。上記積算は、内燃機関５が燃料リーン状態から燃料リッチ状態に切り換えられた後に行われ、途中燃料リーン状態に切り換えられたときに一旦中断されて、その後再び燃料リーン状態に切り換えられたときに再開されてもよい。 For example, in the above embodiment, the upstream side NH 3 concentration estimated value NH 3 _us_mod, the downstream side NO X concentration estimated value N_ds_mod, and the downstream side NO X concentration detected value N_ds_det do not necessarily have to be integrated in consecutive periods. The above integration is performed after the internal combustion engine 5 is switched from the fuel lean state to the fuel rich state, is interrupted once when the fuel lean state is switched on the way, and is restarted when it is switched to the fuel lean state again. May be done.

また、上記実施形態では、制御装置１００がＮＯX選択還元触媒１３の異常の有無を判別するだけでなく、ＮＯX選択還元触媒１３の欠落又は劣化を判別するようになっていたが、本発明はかかる例に限定されない。制御装置１００は、ＮＯX選択還元触媒１３の異常の有無のみを判別するようになっていてもよい。 Further, in the above-described embodiment, the control device 100 not only determines whether the NO X selective reduction catalyst 13 is abnormal, but also determines whether the NO X selective reduction catalyst 13 is missing or deteriorated. Is not limited to such an example. The control device 100 may determine only whether or not there is an abnormality in the NO X selective reduction catalyst 13.

５・・・内燃機関、１０・・・排気浄化装置、１１・・・排気管、１３・・・ＮＯX選択還元触媒、１５・・・ＮＯX吸蔵触媒、２３・・・アンモニア濃度センサ、１００・・・制御装置（診断装置）、１１２・・・上流側ＮＯX濃度取得部、１１３・・・上流側アンモニア濃度推定部、１１４・・・下流側ＮＯX濃度推定部、１１６・・・センサ値検出部、１１８・・・判定部 5... Internal combustion engine, 10... Exhaust gas purification device, 11... Exhaust pipe, 13... NO X selective reduction catalyst, 15... NO X storage catalyst, 23... Ammonia concentration sensor, 100 ... controller (diagnostic device), 112 ... upstream NO X concentration acquisition unit, 113 ... upstream ammonia concentration estimating unit, 114 ... downstream NO X concentration estimating unit, 116 ... sensor Value detector, 118... Judgment unit

Claims (7)

内燃機関の排気通路に上流側から順にＮＯX吸蔵触媒とＮＯX選択還元触媒とを備えた排気浄化装置における前記ＮＯX選択還元触媒の異常を診断する診断装置において、
前記ＮＯX選択還元触媒よりも下流側の排気通路内のＮＯX濃度の推定値である下流側ＮＯX濃度推定値を算出する下流側ＮＯX濃度推定部と、
前記ＮＯX選択還元触媒よりも下流側の排気通路に備えられたＮＯX濃度センサのセンサ値を取得するセンサ値検出部と、
前記下流側ＮＯX濃度推定値及び前記センサ値に基づいて前記ＮＯX選択還元触媒の異常を判定する判定部と、
を備える、診断装置。 In a diagnostic device for diagnosing an abnormality of the NO X selective reduction catalyst in an exhaust purification device including an NO X storage catalyst and a NO X selective reduction catalyst in order from an upstream side in an exhaust passage of an internal combustion engine,
And the downstream NO X density estimating unit that calculates a downstream NO X concentration estimated value is an estimated value of the NO X concentration in the exhaust passage downstream of the the NO X selective reducing catalyst,
A sensor value detection unit that acquires a sensor value of a NO X concentration sensor provided in the exhaust passage downstream of the NO X selective reduction catalyst;
A determination unit that determines an abnormality of the NO X selective reduction catalyst based on the downstream NO X concentration estimated value and the sensor value;
A diagnostic device comprising: 前記判定部は、前記下流側ＮＯX濃度推定値の積算値及び前記センサ値の積算値を用いて、前記ＮＯX選択還元触媒の異常を判定する、請求項１に記載の診断装置。 The diagnostic device according to claim 1, wherein the determination unit determines an abnormality of the NO X selective reduction catalyst by using an integrated value of the downstream side NO X concentration estimated value and an integrated value of the sensor value. 前記判定部は、前記ＮＯX吸蔵触媒からアンモニアが流出する期間における前記下流側ＮＯX濃度推定値及び前記センサ値を用いて前記ＮＯX選択還元触媒の異常を判定する、請求項１又は２に記載の診断装置。 The determination unit determines an abnormality of the NO X selective reduction catalyst by using the downstream NO X concentration estimated value and the sensor value during a period in which ammonia flows out from the NO X storage catalyst. The diagnostic device described. 前記ＮＯX吸蔵触媒よりも下流側、かつ、前記ＮＯX選択還元触媒よりも上流側の排気通路内のアンモニア濃度の推定値である上流側アンモニア濃度推定値を求める上流側アンモニア濃度推定部をさらに備え、
前記判定部は、前記上流側アンモニア濃度推定値、前記下流側ＮＯX濃度推定値及び前記センサ値に基づいて、前記ＮＯX選択還元触媒の欠落及び劣化を判定する、請求項１に記載の診断装置。 An upstream-side ammonia concentration estimation unit that obtains an upstream-side ammonia concentration estimated value that is an estimated value of the ammonia concentration in the exhaust passage on the downstream side of the NO X storage catalyst and on the upstream side of the NO X selective reduction catalyst is further provided. Prepare,
The diagnosis according to claim 1, wherein the determination unit determines whether the NO x selective reduction catalyst is missing or deteriorated based on the upstream side ammonia concentration estimated value, the downstream side NO x concentration estimated value and the sensor value. apparatus. 前記判定部は、前記上流側アンモニア濃度推定値の積算値、前記下流側ＮＯX濃度推定値の積算値及び前記センサ値の積算値を用いて、前記ＮＯX選択還元触媒の欠落及び劣化を判定する、請求項４に記載の診断装置。 The determination unit determines the lack and deterioration of the NO X selective reduction catalyst by using the integrated value of the upstream side ammonia concentration estimated value, the integrated value of the downstream side NO X concentration estimated value and the integrated value of the sensor value. The diagnostic device according to claim 4, wherein 前記判定部は、前記ＮＯX吸蔵触媒からアンモニアが流出する期間における前記上流側アンモニア濃度推定値、前記下流側ＮＯX濃度推定値及び前記センサ値を用いて前記ＮＯX選択還元触媒の欠落及び劣化を判定する、請求項４又は５に記載の診断装置。 The determination unit uses the upstream side ammonia concentration estimated value, the downstream side NO x concentration estimated value and the sensor value during the period in which ammonia flows out from the NO x storage catalyst, and the lack and deterioration of the NO x selective reduction catalyst. The diagnostic device according to claim 4 or 5, which determines whether or not 内燃機関の排気通路に備えられたＮＯX吸蔵触媒と、
前記ＮＯX吸蔵触媒よりも下流側の排気通路に備えられたＮＯX選択還元触媒と、
前記ＮＯX選択還元触媒よりも下流側の排気通路に備えられたＮＯX濃度センサと、
前記ＮＯX選択還元触媒の異常を診断する診断装置と、を備えた内燃機関の排気浄化装置において、
前記診断装置は、
前記ＮＯX選択還元触媒よりも下流側の排気通路内のＮＯX濃度の推定値である下流側ＮＯX濃度推定値を算出する下流側ＮＯX濃度推定部と、
前記ＮＯX選択還元触媒よりも下流側の排気通路に備えられたＮＯX濃度センサのセンサ値を取得するセンサ値検出部と、
前記下流側ＮＯX濃度推定値及び前記センサ値に基づいて前記ＮＯX選択還元触媒の異常を判定する判定部と、
を備える、内燃機関の排気浄化装置。
A NO x storage catalyst provided in the exhaust passage of the internal combustion engine,
A NO x selective reduction catalyst provided in the exhaust passage downstream of the NO x storage catalyst;
A NO x concentration sensor provided in the exhaust passage downstream of the NO x selective reduction catalyst;
An exhaust gas purification device for an internal combustion engine, comprising: a diagnostic device for diagnosing an abnormality of the NO x selective reduction catalyst,
The diagnostic device is
And the downstream NO X density estimating unit that calculates a downstream NO X concentration estimated value is an estimated value of the NO X concentration in the exhaust passage downstream of the the NO X selective reducing catalyst,
A sensor value detection unit that acquires a sensor value of a NO X concentration sensor provided in the exhaust passage downstream of the NO X selective reduction catalyst;
A determination unit that determines an abnormality of the NO X selective reduction catalyst based on the downstream NO X concentration estimated value and the sensor value;
An exhaust gas purification device for an internal combustion engine, comprising:
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