JP4894765B2 - Exhaust purification device - Google Patents

Exhaust purification device Download PDF

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JP4894765B2
JP4894765B2 JP2008008958A JP2008008958A JP4894765B2 JP 4894765 B2 JP4894765 B2 JP 4894765B2 JP 2008008958 A JP2008008958 A JP 2008008958A JP 2008008958 A JP2008008958 A JP 2008008958A JP 4894765 B2 JP4894765 B2 JP 4894765B2
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exhaust gas
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川島　　一仁
圭介 田代
武久 藤田
誠二 菊池
嘉夫 田川
正広 津田
瑞喜 穴井
健 王
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Mitsubishi Motors Corp
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Description

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

従来から内燃機関、例えばディーゼル機関等の排気中のＮＯｘを浄化するために、排気系にＮＯｘ吸蔵触媒を配し、定期的なリッチ運転などによりＮＯｘ吸蔵触媒へ還元剤を供給することにより、リーン運転期間中に吸蔵したＮＯｘを放出又は還元する排気浄化装置が知られている。   Conventionally, in order to purify NOx in the exhaust of an internal combustion engine such as a diesel engine, a NOx storage catalyst is arranged in the exhaust system, and a reducing agent is supplied to the NOx storage catalyst by periodic rich operation, etc. An exhaust purification device that releases or reduces NOx occluded during an operation period is known.

そして、このような排気浄化装置の内、ＮＯｘ吸蔵触媒に還元剤を供給する方法として、内燃機関の筒内でのリッチ燃焼に因らず、内燃機関の排気ポートからＮＯｘ吸蔵触媒の入口までの排気管中に排気管インジェクタを有する還元剤供給手段を配して還元剤（例えば、燃料等）を供給する排気浄化装置が知られている。   In such an exhaust purification device, as a method of supplying the reducing agent to the NOx storage catalyst, the exhaust port from the internal combustion engine to the inlet of the NOx storage catalyst is not involved, regardless of the rich combustion in the cylinder of the internal combustion engine. 2. Description of the Related Art There is known an exhaust emission control device that supplies a reducing agent (for example, fuel) by arranging a reducing agent supply means having an exhaust pipe injector in an exhaust pipe.

また、上述した排気管インジェクタを有する排気浄化装置における排気管インジェクタの異常を判定する技術として、ＮＯｘ吸蔵触媒の下流に排気管中の酸素濃度に相関した出力が得られるセンサ（例えば、Ｏ２センサ）等を配して、排気管インジェクタが正常なときのセンサ出力値から所定値以上の偏差が生じる場合に排気管インジェクタの目詰まり等による異常として検出する異常検出装置を有する排気浄化装置が知られている。このような従来の排気浄化装置の一例が下記特許文献１に開示されている。   Further, as a technique for determining an abnormality of the exhaust pipe injector in the exhaust purification apparatus having the exhaust pipe injector described above, a sensor (for example, an O2 sensor) that can obtain an output correlated with the oxygen concentration in the exhaust pipe downstream of the NOx storage catalyst. An exhaust purification device having an abnormality detection device that detects an abnormality due to clogging of an exhaust pipe injector or the like when a deviation of a predetermined value or more occurs from a sensor output value when the exhaust pipe injector is normal is known. ing. An example of such a conventional exhaust purification device is disclosed in Patent Document 1 below.

特開２００２−８９３２７号公報JP 2002-89327 A

上述した従来の排気浄化装置において、排気管インジェクタは排気管に形成した排気管インジェクタの取付部に設置されるが、この取付部近傍にはデポジットの堆積が生じる場合がある。これは例えば、排気管インジェクタから噴射された還元剤の内、噴射空間を形成する壁面に付着した微量の還元剤が気化せずに排気中の粒子状物質（ＰＭ）を壁面に固定するバインダーとなることにより、デポジットの堆積が発生してしまうためである。   In the above-described conventional exhaust purification apparatus, the exhaust pipe injector is installed at a mounting portion of the exhaust pipe injector formed in the exhaust pipe, and deposits may be deposited near the mounting portion. This includes, for example, a binder that fixes particulate matter (PM) in the exhaust gas to the wall without vaporizing a small amount of the reducing agent that has adhered to the wall that forms the injection space among the reducing agent injected from the exhaust pipe injector. This is because deposit accumulation occurs.

また、このデポジットの堆積は、還元剤の噴射形状が噴射空間を形成する壁面に直接に接することがなくても、還元剤噴射時に生じる負圧により還元剤噴射方向とは逆方向に巻き込まれる還元剤が噴射空間を形成する壁面に付着することによっても発生する虞がある。   In addition, the deposit is deposited even if the injection shape of the reducing agent does not directly contact the wall surface forming the injection space, and the reduction agent is caught in the direction opposite to the reducing agent injection direction due to the negative pressure generated during the reducing agent injection. There is also a possibility that it may occur when the agent adheres to the wall surface forming the injection space.

図４は、排気管インジェクタにより還元剤が噴射される噴射空間を形成する壁面にデポジットが堆積する様子を示した図である。図４（ａ）に示すように、噴射空間５１のような狭小な空間において排気管インジェクタ５０から噴射した還元剤５２によって図４（ａ）中に矢印Ｒで示すように高速の流れが作られると、その閉空間内の気体も図４（ａ）中に矢印Ｂで示すような粘性により引かれて図４（ａ）中に破線で示す位置に負圧が生じ、この負圧に貫徹力の弱い飛散した還元剤５２が図４（ａ）中に矢印Ｃで示すように引き寄せられると、図４（ｂ）に示すように、噴射空間５１を形成する壁面に飛散した還元剤５２が付着してデポジット５３として堆積してしまうためである。   FIG. 4 is a view showing a state where deposits are deposited on the wall surface forming the injection space in which the reducing agent is injected by the exhaust pipe injector. As shown in FIG. 4A, a high-speed flow is created as indicated by an arrow R in FIG. 4A by the reducing agent 52 injected from the exhaust pipe injector 50 in a narrow space such as the injection space 51. Then, the gas in the closed space is also drawn by the viscosity as shown by an arrow B in FIG. 4A, and a negative pressure is generated at a position shown by a broken line in FIG. 4A. When the reducing agent 52 scattered weakly is drawn as shown by arrow C in FIG. 4A, the reducing agent 52 scattered on the wall surface forming the injection space 51 adheres as shown in FIG. 4B. This is because the deposit 53 is deposited.

しかしながら、上述した従来の排気浄化装置における異常検出方法では、排気管インジェクタの噴射流量低下を検出することにより、排気管インジェクタの目詰まり等の異常を検出することは可能であるが、排気管に形成した排気管インジェクタの取付部近傍にデポジットの堆積が生じる場合の異常を検出、判別することは困難である。   However, in the above-described abnormality detection method in the conventional exhaust purification device, it is possible to detect an abnormality such as clogging of the exhaust pipe injector by detecting a decrease in the injection flow rate of the exhaust pipe injector. It is difficult to detect and discriminate abnormalities in the case where deposits are deposited near the attachment portion of the formed exhaust pipe injector.

また、排気管インジェクタの噴射流量低下時と排気管インジェクタの取付部近傍へのデポジットの堆積時とでは修理対応方法が異なるが、従来の排気浄化装置における異常検出方法では、目詰まり等の排気管インジェクタ異常（噴射流量低下）と排気管インジェクタの取付部近傍へのデポジットの堆積による異常とを判別することがでないため、効率よく修理を行うことができない。   In addition, repair methods differ between when the injection flow rate of the exhaust pipe injector is reduced and when deposits are deposited near the mounting area of the exhaust pipe injector. Since it is not possible to discriminate between an abnormality in the injector (decrease in the injection flow rate) and an abnormality due to deposit accumulation in the vicinity of the attachment portion of the exhaust pipe injector, repair cannot be performed efficiently.

以上のことから、本発明は、排気管インジェクタの取付部近傍へのデポジットの堆積による異常を検出することが可能な排気浄化装置を提供することを目的とする。   In view of the above, an object of the present invention is to provide an exhaust emission control device capable of detecting an abnormality caused by deposit accumulation in the vicinity of an attachment portion of an exhaust pipe injector.

上記の課題を解決するための第１の発明に係る排気浄化装置は、内燃機関の気筒の排気ポートに接続され該気筒内から排出された排気を導出する排気管と、該排気管に設置され排気ガスを浄化する浄化手段と、前記浄化手段の上流に配置され該触媒に添加剤を供給する添加剤供給手段と、該添加剤供給手段から添加剤が噴射される噴射空間を有し該添加剤供給手段が取り付けられる取付部と、前記浄化手段の下流に配置され排気ガス中の成分を検出する排気ガス濃度検出手段と、前記添加剤供給手段の駆動開始時と駆動終了時の前記排気ガス濃度検出手段の変化に応じて該添加剤供給手段近傍の前記取付部の内壁面にデポジットが堆積する異常を判定するデポジット堆積判定手段とを備えることを特徴とする。   An exhaust emission control device according to a first aspect of the present invention for solving the above-described problems is provided with an exhaust pipe connected to an exhaust port of a cylinder of an internal combustion engine for leading exhaust exhausted from the cylinder, and installed in the exhaust pipe. A purification means for purifying exhaust gas; an additive supply means disposed upstream of the purification means for supplying an additive to the catalyst; and an injection space through which the additive is injected from the additive supply means. An attachment portion to which the agent supply means is attached; an exhaust gas concentration detection means that is disposed downstream of the purification means to detect components in the exhaust gas; and the exhaust gas at the start and end of driving of the additive supply means And deposit deposition determining means for determining an abnormality in which deposit accumulates on the inner wall surface of the mounting portion in the vicinity of the additive supplying means in accordance with a change in the concentration detecting means.

上記の課題を解決するための第２の発明に係る排気浄化装置は、第１の発明に係る排気浄化装置において、前記内燃機関の制御目標排気ガス濃度を算出し、前記排気ガス濃度検出手段により検出した検出排気ガス濃度が前記制御目標排気ガス濃度に近づくよう前記内燃機関を制御する制御手段を備え、前記デポジット堆積判定手段は、前記添加剤供給手段駆動開始から所定時間が経過した時点において前記検出排気ガス濃度と前記制御目標排気ガス濃度との差が所定値を上回り、かつ、前記添加剤供給手段駆動終了から所定時間が経過した時点において前記制御目標排気ガス濃度と前記検出排気ガス濃度との差が所定値を上回ったとき、前記添加剤供給手段近傍の前記取付部の内壁面にデポジットが堆積する異常が発生したものと判定することを特徴とする。   An exhaust emission control apparatus according to a second aspect of the present invention for solving the above problem is the exhaust emission control apparatus according to the first aspect of the invention, wherein the control target exhaust gas concentration of the internal combustion engine is calculated, and the exhaust gas concentration detection means is used. The control unit controls the internal combustion engine so that the detected exhaust gas concentration detected approaches the control target exhaust gas concentration, and the deposit accumulation determination unit is configured to detect the deposit when a predetermined time has elapsed from the start of driving of the additive supply unit. When the difference between the detected exhaust gas concentration and the control target exhaust gas concentration exceeds a predetermined value and a predetermined time has elapsed since the end of driving the additive supply means, the control target exhaust gas concentration and the detected exhaust gas concentration When the difference exceeds a predetermined value, it is determined that an abnormality has occurred in which deposits accumulate on the inner wall surface of the mounting portion in the vicinity of the additive supply means. The features.

上記の課題を解決するための第３の発明に係る排気浄化装置は、第１の発明又は第２の発明に係る排気浄化装置において、所定期間内に前記還元剤供給手段駆動開始から所定時間が経過した時点において前記検出排気ガス濃度と前記制御目標排気ガス濃度との差が所定値を上回り、かつ、所定期間内に前記添加剤供給手段駆動終了から所定時間が経過した時点において前記制御目標排気ガス濃度と前記検出排気ガス濃度との差が所定値を上回らなかったとき、前記添加剤供給手段に噴射流量が低下する異常が発生したものと判定する噴射流量低下判定手段をさらに備えることを特徴とする。   An exhaust emission control apparatus according to a third aspect of the present invention for solving the above-described problems is the exhaust emission control apparatus according to the first or second aspect of the invention, wherein a predetermined time has elapsed from the start of driving of the reducing agent supply means within a predetermined period. When the elapsed time elapses, the difference between the detected exhaust gas concentration and the control target exhaust gas concentration exceeds a predetermined value, and the control target exhaust gas is reached when a predetermined time elapses from the end of driving of the additive supply means within a predetermined period. When the difference between the gas concentration and the detected exhaust gas concentration does not exceed a predetermined value, the fuel supply device further comprises an injection flow rate lowering determination unit that determines that an abnormality has occurred in the additive supply unit that reduces the injection flow rate. And

上記の課題を解決するための第４の発明に係る排気浄化装置は、第１の発明に係る排気浄化装置において、前記内燃機関の制御目標排気ガス濃度を算出し、前記排気ガス濃度検出手段により検出した検出排気ガス濃度が前記制御目標排気ガス濃度に近づくよう前記内燃機関を制御する制御手段を備え、前記デポジット堆積判定手段は、少なくとも前記添加剤供給手段駆動終了から所定時間が経過した時点において前記制御目標排気ガス濃度と前記検出排気ガス濃度との差が所定値を上回ったとき、前記添加剤供給手段近傍の前記取付部の内壁面にデポジットが堆積する異常が発生したものと判定することを特徴とする。   An exhaust emission control device according to a fourth aspect of the present invention for solving the above problem is the exhaust emission control device according to the first aspect of the invention, wherein the control target exhaust gas concentration of the internal combustion engine is calculated, and the exhaust gas concentration detection means is used. And a control unit that controls the internal combustion engine so that the detected exhaust gas concentration detected approaches the control target exhaust gas concentration, and the deposit accumulation determination unit is at least when a predetermined time has elapsed since the end of driving of the additive supply unit. When the difference between the control target exhaust gas concentration and the detected exhaust gas concentration exceeds a predetermined value, it is determined that an abnormality has occurred in which deposits are accumulated on the inner wall surface of the mounting portion in the vicinity of the additive supply means. It is characterized by.

本発明によれば、排気管インジェクタ近傍の取付部の内壁面へのデポジットの堆積による異常を判定することが可能である。   According to the present invention, it is possible to determine an abnormality caused by deposit accumulation on the inner wall surface of the mounting portion in the vicinity of the exhaust pipe injector.

以下、本発明に係る排気浄化装置の一実施形態について図１〜図３を用いて説明する。ここで、図１は本発明の一実施形態に係る排気浄化装置における異常判定方法の動作フローを示した図、図２は正常時、デポジット堆積時及び目詰まり時の還元剤供給手段（添加剤供給手段）駆動開始及び終了後における検出Ａ／Ｆの変化の様子を示した図、図３は本発明の一実施形態に係る排気浄化装置の装置構成を示した模式図である。   Hereinafter, an embodiment of an exhaust emission control device according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a diagram showing an operation flow of an abnormality determination method in an exhaust purification system according to an embodiment of the present invention, and FIG. 2 is a reducing agent supply means (additive) at normal time, during deposit accumulation, and when clogged. FIG. 3 is a schematic diagram showing a configuration of an exhaust emission control apparatus according to an embodiment of the present invention. FIG. 3 is a diagram showing a change in detection A / F after the start and end of driving.

始めに、本発明の一実施形態に係る排気浄化装置の装置構成について説明する。図３（ａ）に示すように、内燃機関１における気筒の排気ポート２には、排気を導出する排気管３ａ，３ｂが接続されている。この排気管３ａ，３ｂの中間には、排気中のＮＯｘを吸蔵して排気を浄化する浄化手段としてＮＯｘ吸蔵触媒４が設置されている。   First, the device configuration of the exhaust emission control device according to an embodiment of the present invention will be described. As shown in FIG. 3A, exhaust pipes 3 a and 3 b for leading exhaust are connected to the exhaust port 2 of the cylinder in the internal combustion engine 1. Between the exhaust pipes 3a and 3b, a NOx storage catalyst 4 is installed as a purifying means for storing NOx in the exhaust and purifying the exhaust.

排気ポート２とＮＯｘ吸蔵触媒４との間の排気管３ａには、燃料等の還元剤（添加剤）を供給する排気管インジェクタ５が配置される。また、排気管インジェクタ５から還元剤が噴射される噴射空間を有する排気管インジェクタ５の取付部６が排気管３ａに突出して形成されている。そして、前記排気管インジェクタ５は取付部６に設置されている。   An exhaust pipe injector 5 that supplies a reducing agent (additive) such as fuel is disposed in the exhaust pipe 3 a between the exhaust port 2 and the NOx storage catalyst 4. Further, a mounting portion 6 of the exhaust pipe injector 5 having an injection space in which the reducing agent is injected from the exhaust pipe injector 5 is formed so as to protrude from the exhaust pipe 3a. The exhaust pipe injector 5 is installed in the attachment portion 6.

ＮＯｘ吸蔵触媒４の下流の排気管３ｂにはリニア特性で空燃比（以下、Ａ／Ｆという）を検出する排気ガス検出手段であるリニア空燃比センサ（以下、空燃比センサという）７が設置されている。なお、排気管インジェクタ５には還元剤を供給するポンプ等（図示省略）が取り付けられ、これら排気管インジェクタ５やポンプ等により還元剤供給手段が構成されている。   The exhaust pipe 3b downstream of the NOx storage catalyst 4 is provided with a linear air-fuel ratio sensor (hereinafter referred to as air-fuel ratio sensor) 7 which is an exhaust gas detection means for detecting an air-fuel ratio (hereinafter referred to as A / F) with linear characteristics. ing. The exhaust pipe injector 5 is provided with a pump or the like (not shown) for supplying a reducing agent, and the exhaust pipe injector 5 and the pump constitute a reducing agent supply means.

空燃比センサ７はＥＣＵ８（制御手段）と電気的に接続され、空燃比センサ７において検出したＡ／Ｆ（以下、検出Ａ／Ｆという）はＥＣＵ８に出力される。また、ＥＣＵ８には排気管インジェクタ５が電気的に接続され、ＥＣＵ８は検出Ａ／Ｆ等に基き、還元剤供給手段を駆動し、排気管インジェクタ５から還元剤を供給する。   The air-fuel ratio sensor 7 is electrically connected to the ECU 8 (control means), and the A / F detected by the air-fuel ratio sensor 7 (hereinafter referred to as detection A / F) is output to the ECU 8. Further, the exhaust pipe injector 5 is electrically connected to the ECU 8, and the ECU 8 drives the reducing agent supply means based on the detection A / F and supplies the reducing agent from the exhaust pipe injector 5.

なお、ＥＣＵ８は、中央演算処理装置やＲＡＭやＲＯＭ等を有し、種々の処理や記憶を行うことが可能である。そして、ＥＣＵ８は、内燃機関１の制御目標Ａ／Ｆを算出し、検出Ａ／Ｆを制御目標Ａ／Ｆに近づけるように制御している。このため、排気管インジェクタ５が正常に機能している場合には検出Ａ／Ｆと制御目標Ａ／Ｆとは近い値となっている。   The ECU 8 includes a central processing unit, RAM, ROM, and the like, and can perform various processes and storage. The ECU 8 calculates the control target A / F of the internal combustion engine 1 and controls the detected A / F so as to approach the control target A / F. For this reason, when the exhaust pipe injector 5 is functioning normally, the detection A / F and the control target A / F are close to each other.

また、上述した排気浄化装置の装置構成の他にも、図３（ｂ）に示すように、排気管１０ａ，１０ｂ，１０ｃ，１０ｄに排気ポート２側から順にディーゼル用酸化触媒（以下、酸化触媒という）又はＮＯｘ吸蔵触媒１１、ＮＯｘ吸蔵触媒１２、ディーゼルパティキュレートフィルター１３を設置する場合、酸化触媒又はＮＯｘ吸蔵触媒１１とＮＯｘ吸蔵触媒１２との間の排気管１０ｂ、ＮＯｘ吸蔵触媒１２とパティキュレートフィルタ１３との間の排気管１０ｃ、パティキュレートフィルタ１３の下流の排気管１０ｄの内、一箇所又は複数箇所に空燃比センサ１４，１５，１６を設置する構成とすることも可能である。   In addition to the apparatus configuration of the exhaust purification device described above, as shown in FIG. 3B, the exhaust pipes 10a, 10b, 10c, and 10d are sequentially connected to the diesel oxidation catalyst (hereinafter referred to as oxidation catalyst) from the exhaust port 2 side. Or when the NOx storage catalyst 11, the NOx storage catalyst 12, and the diesel particulate filter 13 are installed, the exhaust pipe 10b between the oxidation catalyst or the NOx storage catalyst 11 and the NOx storage catalyst 12, the NOx storage catalyst 12 and the particulates. The air-fuel ratio sensors 14, 15, and 16 may be installed at one or a plurality of locations in the exhaust pipe 10 c between the filter 13 and the exhaust pipe 10 d downstream of the particulate filter 13.

次に、本発明に係る排気浄化装置における異常判定方法の原理について説明する。
図２に示すように、排気管インジェクタ５に目詰まり等の噴射流量が低下する異常が発生した場合、排気管インジェクタ５が正常に機能している正常時よりも単位時間当たりの噴射流量が低下してしまう。 Next, the principle of the abnormality determination method in the exhaust emission control device according to the present invention will be described.
As shown in FIG. 2, when an abnormality occurs in the exhaust pipe injector 5 such as clogging, the injection flow rate per unit time is lower than when the exhaust pipe injector 5 is functioning normally. Resulting in.

このため、排気管インジェクタ５に目詰まり等の噴射流量が低下する異常が発生した場合、図２中に実線で示す正常時に比べ、図２中に一点鎖線で示すように還元剤供給手段の駆動開始Ｓ後、速やかにリッチ化するものの正常時の検出Ａ／Ｆまではリッチ化せず、還元剤供給手段の駆動終了Ｅ後、速やかに正常時の値までリーン化する。   For this reason, when an abnormality occurs in the exhaust pipe injector 5 such as clogging, which causes a decrease in the injection flow rate, the reducing agent supply means is driven as shown by a one-dot chain line in FIG. After the start S, it is quickly enriched, but is not enriched until the normal detection A / F, and after the end of the driving E of the reducing agent supply means, it is quickly made lean to the normal value.

これに対し、排気管インジェクタ５近傍の取付部６の内壁面にデポジットの堆積が生じる異常の場合、正常時と単位時間当たりの噴射流量は同じではあるが、噴射した還元剤がデポジットに付着、流下するなどして還元剤が排気中に適切に噴射されなくなってしまう。   On the other hand, in the case of an abnormality in which deposits are accumulated on the inner wall surface of the mounting portion 6 in the vicinity of the exhaust pipe injector 5, the injected flow rate per unit time is the same as that in the normal state, but the injected reducing agent adheres to the deposit. The reducing agent will not be properly injected into the exhaust gas by flowing down.

このため、図２中に実線で示す正常時に比べ、図２中に破線で示すように還元剤供給手段の駆動開始Ｓ後、リッチ化するものの正常時の検出Ａ／Ｆまでリッチ化せず、還元剤供給手段の駆動終了Ｅ後、速やかにリーン化することなく、正常時の検出Ａ／Ｆまでリーン化するのに時間がかってしまう。   For this reason, compared with the normal time indicated by the solid line in FIG. 2, as shown by the broken line in FIG. After the end of driving E of the reducing agent supply means, it takes time to lean to normal detection A / F without promptly leaning.

このように、排気管インジェクタ５に目詰まり等の噴射流量が低下する異常が発生した場合と、排気管インジェクタ５近傍の取付部６の内壁面にデポジットの堆積が生じる異常の場合とでは、上述したように検出Ａ／Ｆのとる値が異なる。このため、この差異に着目することで排気管インジェクタ５に目詰まり等の噴射流量が低下する異常と排気管インジェクタ５近傍の取付部６の内壁面にデポジットの堆積が生じる異常とを判別することが可能となる。なお、正常時の検出Ａ／ＦはＥＣＵ８による制御目標Ａ／Ｆと近い値となり、後述する実際の異常判定処理時には上述した正常時の検出Ａ／Ｆに替え、制御目標Ａ／Ｆを用いて異常判定処理を行う。   As described above, in the case where an abnormality in which the injection flow rate such as clogging is reduced occurs in the exhaust pipe injector 5 and in the case where the deposit is accumulated on the inner wall surface of the mounting portion 6 in the vicinity of the exhaust pipe injector 5, As described above, the detection A / F takes different values. Therefore, by paying attention to this difference, it is possible to discriminate between an abnormality in which the injection flow rate such as clogging in the exhaust pipe injector 5 is reduced and an abnormality in which deposits are deposited on the inner wall surface of the mounting portion 6 in the vicinity of the exhaust pipe injector 5. Is possible. Note that the detection A / F at normal time is close to the control target A / F by the ECU 8, and the control target A / F is used instead of the normal detection A / F at the time of actual abnormality determination processing described later. An abnormality determination process is performed.

次に、本発明の一実施形態に係る排気浄化装置における異常判定方法の動作フローについて説明する。
図１に示すように、異常判定処理の開始後、ステップＳ１において、ＥＣＵ８は、還元剤供給手段を駆動する。ＥＣＵ８は、ステップＳ１を実行後、ステップＳ２を実行する。 Next, an operation flow of the abnormality determination method in the exhaust emission control device according to the embodiment of the present invention will be described.
As shown in FIG. 1, after starting the abnormality determination process, in step S1, the ECU 8 drives the reducing agent supply means. The ECU 8 executes step S2 after executing step S1.

ステップＳ２において、ＥＣＵ８は、図２中に示した還元剤供給手段の駆動開始時Ｓから所定時間Ｔが経過した時点において、検出Ａ／Ｆと制御目標Ａ／Ｆとの差をΔＡ／Ｆ（Ｓ＋Ｔ）としたときに、「ΔＡ／Ｆ（Ｓ＋Ｔ）＞所定値Ｘ」の状態が所定回数Ｎ回（Ｎ≧１）成立したかどうか判断する（この条件を条件Ａとする）。なお、条件Ａは、「ΔＡ／Ｆ（Ｓ＋Ｔ）＞所定値Ｘ」が過去に所定回数Ｎ回成立したかにより判断してもよいし、所定回数Ｎ回に亘り連続して成立したかにより判断してもよいし、所定の期間内に所定回数Ｎ回成立したかにより判断してもよい。   In step S2, the ECU 8 determines the difference between the detected A / F and the control target A / F by ΔA / F (at the time when the predetermined time T has elapsed from the start of driving S of the reducing agent supply means shown in FIG. S + T), it is determined whether or not the state of “ΔA / F (S + T)> predetermined value X” is established N times (N ≧ 1) (this condition is defined as condition A). The condition A may be determined based on whether “ΔA / F (S + T)> predetermined value X” has been established N times a predetermined number of times in the past, or based on whether the condition A has been continuously established N times. Alternatively, the determination may be made based on whether a predetermined number of times N has been established within a predetermined period.

ＥＣＵ８は、条件Ａが成立した場合、ステップＳ３を実行する。また、ＥＣＵ８は、条件Ａが成立しなかった場合、異常判定処理を終了する。なお、所定時間Ｔ及び所定値Ｘは内燃機関１の種類等によって適切な値が異なるため、内燃機関１の種類等に応じて適宜設定するようにする。また、所定回数Ｎの回数を増やすことにより、異常判定の精度を高め、誤判定を防止することもできる。   When the condition A is satisfied, the ECU 8 executes step S3. Further, when the condition A is not satisfied, the ECU 8 ends the abnormality determination process. The predetermined time T and the predetermined value X are appropriately set depending on the type of the internal combustion engine 1 and the like because appropriate values differ depending on the type of the internal combustion engine 1 and the like. Further, by increasing the number of times N, the accuracy of abnormality determination can be increased and erroneous determination can be prevented.

ステップＳ３において、ＥＣＵ８は、図２中に示した還元剤供給手段の駆動終了時Ｅから所定時間ｔが経過した時点において、制御目標Ａ／Ｆと検出Ａ／Ｆとの差をΔＡ／Ｆ（Ｅ＋ｔ）としたときに、「ΔＡ／Ｆ（Ｅ＋ｔ）＞所定値Ｙ」の状態が所定回数Ｎ回（Ｎ≧１）成立したかどうか判断する（この条件を条件Ｂとする）。なお、条件Ｂは、「ΔＡ／Ｆ（Ｅ＋ｔ）＞所定値Ｘ」が過去に所定回数Ｎ回成立したかにより判断してもよいし、所定回数Ｎ回に亘り連続して成立したかにより判断してもよいし、所定の期間内に所定回数Ｎ回成立したかにより判断してもよい。   In step S3, the ECU 8 calculates the difference between the control target A / F and the detected A / F by ΔA / F (at the time when the predetermined time t has elapsed since the driving end time E of the reducing agent supply means shown in FIG. E + t), it is determined whether or not the state of “ΔA / F (E + t)> predetermined value Y” has been established N times (N ≧ 1) (this condition is defined as condition B). The condition B may be determined based on whether “ΔA / F (E + t)> predetermined value X” has been established N times a predetermined number of times in the past, or based on whether it has been continuously established N times a predetermined number of times. Alternatively, the determination may be made based on whether a predetermined number of times N has been established within a predetermined period.

ＥＣＵ８は、条件Ｂが成立した場合、ステップＳ４を実行する。また、ＥＣＵ８は、条件Ｂが成立しなかった場合、ステップＳ５を実行する。なお、所定時間ｔ及び所定値Ｙは内燃機関１の種類等によって適切な値が異なるため、内燃機関１の種類等に応じて適宜設定するようにする。また、所定回数Ｎの数値を増やすことにより、異常判定の精度を高め、誤判定を防止することもできる。   When the condition B is satisfied, the ECU 8 executes step S4. Moreover, ECU8 performs step S5, when the conditions B are not materialized. The predetermined time t and the predetermined value Y are appropriately set according to the type of the internal combustion engine 1 and the like because appropriate values differ depending on the type of the internal combustion engine 1 and the like. Further, by increasing the numerical value of the predetermined number N, it is possible to improve the accuracy of abnormality determination and prevent erroneous determination.

ステップＳ４において、ＥＣＵ８は、排気管インジェクタ５近傍の取付部６の内壁面にデポジットの堆積が生じる異常が発生したことを運転者等に警告する。この警告は、例えばインストルメントパネルにインジケータ等を設け、このインジケータを点灯させることにより行う。   In step S <b> 4, the ECU 8 warns the driver or the like that an abnormality has occurred in which deposits accumulate on the inner wall surface of the mounting portion 6 near the exhaust pipe injector 5. This warning is performed, for example, by providing an indicator or the like on the instrument panel and lighting this indicator.

また、ＥＣＵ８は、排気管インジェクタ５近傍の取付部６の内壁面にデポジットの堆積が生じる異常が発生した時刻等の情報を記憶する。このように、異常が発生した時刻等の情報を記憶しておくことにより、修理時に的確に効率よく修理を行うことができる。ＥＣＵ８は、ステップＳ４を実行後、異常判定処理を終了する。   In addition, the ECU 8 stores information such as the time when an abnormality occurs in which deposits accumulate on the inner wall surface of the mounting portion 6 near the exhaust pipe injector 5. As described above, by storing information such as the time when the abnormality occurred, repair can be performed accurately and efficiently at the time of repair. After executing step S4, the ECU 8 ends the abnormality determination process.

ステップＳ５において、ＥＣＵ８は、排気管インジェクタ５に目詰まり等の噴射流量が低下する異常が発生したことを運転者等に警告する。この警告は、例えばインストルメントパネルにインジケータ等を設け、このインジケータを点灯させることにより行う。   In step S <b> 5, the ECU 8 warns the driver or the like that an abnormality has occurred in the exhaust pipe injector 5 such as clogging that causes the injection flow rate to decrease. This warning is performed, for example, by providing an indicator or the like on the instrument panel and lighting this indicator.

また、ＥＣＵ８は、排気管インジェクタ５に目詰まり等の噴射流量が低下する異常が発生した時刻等の情報を記憶する。このように、異常が発生した時刻等の情報を記憶しておくことにより、修理時に的確に効率よく修理を行うことができる。ＥＣＵ８は、ステップＳ５を実行後、異常判定処理を終了する。   Further, the ECU 8 stores information such as the time when an abnormality has occurred in the exhaust pipe injector 5, such as clogging, that causes a decrease in the injection flow rate. As described above, by storing information such as the time when the abnormality occurred, repair can be performed accurately and efficiently at the time of repair. The ECU 8 ends the abnormality determination process after executing Step S5.

以上のように、本発明に係る排気浄化装置によれば、排気管インジェクタ５近傍の取付部６の内壁面へのデポジットの堆積による異常を判定することが可能である。また、目詰まり等の噴射流量が低下する異常と排気管インジェクタ５近傍の取付部６の内壁面へのデポジットの堆積が生じる異常とを判別することが可能である。   As described above, according to the exhaust gas purification apparatus of the present invention, it is possible to determine an abnormality caused by deposit accumulation on the inner wall surface of the attachment portion 6 in the vicinity of the exhaust pipe injector 5. Further, it is possible to discriminate between an abnormality in which the injection flow rate such as clogging is reduced and an abnormality in which deposits are accumulated on the inner wall surface of the mounting portion 6 in the vicinity of the exhaust pipe injector 5.

なお、上記実施形態では、添加剤として燃料を用いて説明したが、触媒に供給するものであれば燃料に限らず、尿素やアンモニア等の還元剤や空気等の二次エアでもよい。
また、上記実施形態では、浄化手段としてＮＯｘ吸蔵触媒で説明したが、浄化手段としては、三元触媒や酸化触媒、またはパティキュレートフィルタ等、添加剤が供給されるものであればよい。
また、上記実施形態では、排気ガス検出手段として空燃比センサで説明したが、排気ガス検出手段としては、添加剤に応じてＮＯｘセンサやＮＨ３センサでもよい。 In the above embodiment, the fuel is used as the additive. However, the fuel is not limited to the fuel as long as it is supplied to the catalyst, and a secondary air such as a reducing agent such as urea or ammonia or air may be used.
In the above embodiment, the NOx occlusion catalyst has been described as the purification means. However, the purification means may be any one that is supplied with an additive such as a three-way catalyst, an oxidation catalyst, or a particulate filter.
In the above embodiment, the air-fuel ratio sensor is described as the exhaust gas detection means. However, the exhaust gas detection means may be a NOx sensor or an NH3 sensor depending on the additive.

本発明は、例えば内燃機関、特にディーゼルエンジンに設置される排気浄化装置の異常判定に利用することが可能である。   The present invention can be used for abnormality determination of an exhaust purification device installed in, for example, an internal combustion engine, particularly a diesel engine.

本発明の一実施形態に係る排気浄化装置における異常判定方法の動作フローを示した図である。It is the figure which showed the operation | movement flow of the abnormality determination method in the exhaust gas purification apparatus which concerns on one Embodiment of this invention. 正常時、デポジット堆積時及び目詰まり時の還元剤供給手段駆動開始及び終了後における検出Ａ／Ｆの変化の様子を示した図である。It is the figure which showed the mode of change of detection A / F after the start of a reducing agent supply means drive at the time of normality, deposit accumulation, and clogging. 本発明の一実施形態に係る排気浄化装置の装置構成を示した模式図である。It is the schematic diagram which showed the apparatus structure of the exhaust gas purification apparatus which concerns on one Embodiment of this invention. 排気管インジェクタにより還元剤が噴射される噴射空間を形成する壁面にデポジットが堆積する様子を示した図である。It is the figure which showed a mode that the deposit accumulated on the wall surface which forms the injection space in which a reducing agent is injected by an exhaust pipe injector.

符号の説明Explanation of symbols

１ 内燃機関
２ 排気ポート
３ａ，３ｂ 排気管
４ ＮＯｘ吸蔵触媒
５ 排気管インジェクタ
６ 排気管インジェクタ取付部
７ 空燃比センサ
８ ＥＣＵ
１０ａ，１０ｂ，１０ｃ，１０ｄ 排気管
１１ 酸化触媒又はＮＯｘ吸蔵触媒
１２ ＮＯｘ吸蔵触媒
１３ パティキュレートフィルタ
１４，１５，１６ 空燃比センサ DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust port 3a, 3b Exhaust pipe 4 NOx storage catalyst 5 Exhaust pipe injector 6 Exhaust pipe injector attachment part 7 Air-fuel ratio sensor 8 ECU
10a, 10b, 10c, 10d Exhaust pipe 11 Oxidation catalyst or NOx storage catalyst 12 NOx storage catalyst 13 Particulate filters 14, 15, 16 Air-fuel ratio sensor

Claims (4)

内燃機関の気筒の排気ポートに接続され該気筒内から排出された排気を導出する排気管と、
該排気管に設置され排気ガスを浄化する浄化手段と、
前記浄化手段の上流に配置され該触媒に添加剤を供給する添加剤供給手段と、
該添加剤供給手段から添加剤が噴射される噴射空間を有し該添加剤供給手段が取り付けられる取付部と、
前記浄化手段の下流に配置され排気ガス中の成分を検出する排気ガス濃度検出手段と、
前記添加剤供給手段の駆動開始時と駆動終了時の前記排気ガス濃度検出手段の変化に応じて該添加剤供給手段近傍の前記取付部の内壁面にデポジットが堆積する異常を判定するデポジット堆積判定手段と
を備える
ことを特徴とする排気浄化装置。 An exhaust pipe connected to an exhaust port of a cylinder of the internal combustion engine and leading to exhaust exhausted from the cylinder;
A purification means installed in the exhaust pipe for purifying exhaust gas;
An additive supply means disposed upstream of the purification means for supplying an additive to the catalyst;
A mounting portion having an injection space through which the additive is injected from the additive supply means and to which the additive supply means is attached;
Exhaust gas concentration detecting means arranged downstream of the purifying means for detecting components in the exhaust gas;
Deposit accumulation determination for determining an abnormality in which deposit accumulates on the inner wall surface of the mounting portion in the vicinity of the additive supply means according to a change in the exhaust gas concentration detection means at the start and end of driving of the additive supply means And an exhaust emission control device. 前記内燃機関の制御目標排気ガス濃度を算出し、前記排気ガス濃度検出手段により検出した検出排気ガス濃度が前記制御目標排気ガス濃度に近づくよう前記内燃機関を制御する制御手段を備え、
前記デポジット堆積判定手段は、
前記添加剤供給手段駆動開始から所定時間が経過した時点において前記検出排気ガス濃度と前記制御目標排気ガス濃度との差が所定値を上回り、
かつ、前記添加剤供給手段駆動終了から所定時間が経過した時点において前記制御目標排気ガス濃度と前記検出排気ガス濃度との差が所定値を上回ったとき、
前記添加剤供給手段近傍の前記取付部の内壁面にデポジットが堆積する異常が発生したものと判定する
ことを特徴とする請求項１に記載の排気浄化装置。 Control means for calculating the control target exhaust gas concentration of the internal combustion engine and controlling the internal combustion engine so that the detected exhaust gas concentration detected by the exhaust gas concentration detection means approaches the control target exhaust gas concentration;
The deposit accumulation determination means includes:
The difference between the detected exhaust gas concentration and the control target exhaust gas concentration exceeds a predetermined value at the time when a predetermined time has elapsed from the start of driving the additive supply means,
And, when the difference between the control target exhaust gas concentration and the detected exhaust gas concentration exceeds a predetermined value at the time when a predetermined time has elapsed since the end of driving the additive supply means,
2. The exhaust emission control device according to claim 1, wherein it is determined that an abnormality has occurred in which deposits accumulate on an inner wall surface of the attachment portion in the vicinity of the additive supply means. 所定期間内に前記還元剤供給手段駆動開始から所定時間が経過した時点において前記検出排気ガス濃度と前記制御目標排気ガス濃度との差が所定値を上回り、
かつ、所定期間内に前記添加剤供給手段駆動終了から所定時間が経過した時点において前記制御目標排気ガス濃度と前記検出排気ガス濃度との差が所定値を上回らなかったとき、
前記添加剤供給手段に噴射流量が低下する異常が発生したものと判定する噴射流量低下判定手段をさらに備える
ことを特徴とする請求項１又は請求項２に記載の排気浄化装置。 The difference between the detected exhaust gas concentration and the control target exhaust gas concentration exceeds a predetermined value at a time when a predetermined time has elapsed from the start of driving of the reducing agent supply means within a predetermined period,
And, when a predetermined time has elapsed from the end of driving the additive supply means within a predetermined period, when the difference between the control target exhaust gas concentration and the detected exhaust gas concentration does not exceed a predetermined value,
The exhaust emission control device according to claim 1 or 2, further comprising: an injection flow rate reduction determination unit that determines that an abnormality that reduces the injection flow rate has occurred in the additive supply unit. 前記内燃機関の制御目標排気ガス濃度を算出し、前記排気ガス濃度検出手段により検出した検出排気ガス濃度が前記制御目標排気ガス濃度に近づくよう前記内燃機関を制御する制御手段を備え、
前記デポジット堆積判定手段は、
少なくとも前記添加剤供給手段駆動終了から所定時間が経過した時点において前記制御目標排気ガス濃度と前記検出排気ガス濃度との差が所定値を上回ったとき、
前記添加剤供給手段近傍の前記取付部の内壁面にデポジットが堆積する異常が発生したものと判定する
ことを特徴とする請求項１に記載の排気浄化装置。 Control means for calculating the control target exhaust gas concentration of the internal combustion engine and controlling the internal combustion engine so that the detected exhaust gas concentration detected by the exhaust gas concentration detection means approaches the control target exhaust gas concentration;
The deposit accumulation determination means includes:
When a difference between the control target exhaust gas concentration and the detected exhaust gas concentration exceeds a predetermined value at least when a predetermined time has elapsed since the end of driving the additive supply means,
2. The exhaust emission control device according to claim 1, wherein it is determined that an abnormality has occurred in which deposits accumulate on an inner wall surface of the attachment portion in the vicinity of the additive supply means.
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CN105121799A (en) * 2013-04-08 2015-12-02 丰田自动车株式会社 Internal combustion engine control device

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JP3552653B2 (en) * 2000-07-24 2004-08-11 トヨタ自動車株式会社 Diagnosis processing device for reducing agent supply device of internal combustion engine
JP3800016B2 (en) * 2001-02-15 2006-07-19 トヨタ自動車株式会社 Exhaust gas purification device for internal combustion engine
JP4218462B2 (en) * 2003-08-06 2009-02-04 トヨタ自動車株式会社 Reducing agent addition error detection method and reducing agent addition error detection device for exhaust purification catalyst

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CN105121799B (en) * 2013-04-08 2017-10-27 丰田自动车株式会社 The control device of internal combustion engine

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