JP5924688B2 - Exhaust gas recirculation device for internal combustion engine - Google Patents

Exhaust gas recirculation device for internal combustion engine Download PDF

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JP5924688B2
JP5924688B2 JP2012237603A JP2012237603A JP5924688B2 JP 5924688 B2 JP5924688 B2 JP 5924688B2 JP 2012237603 A JP2012237603 A JP 2012237603A JP 2012237603 A JP2012237603 A JP 2012237603A JP 5924688 B2 JP5924688 B2 JP 5924688B2
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egr
filter
exhaust
passage
pressure
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JP2014088776A (en
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信吉 高澤
信吉 高澤
智 九嶋
智 九嶋
治郎 安田
治郎 安田
光彦 川畑
光彦 川畑
藤原　明彦
明彦 藤原
研介 高橋
研介 高橋
幸二 土田
幸二 土田
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Honda Motor Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/35—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with means for cleaning or treating the recirculated gases, e.g. catalysts, condensate traps, particle filters or heaters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/06—Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
    • F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Description

本発明は、内燃機関の排気還流装置に関する。詳しくは、ＥＧＲ通路に流入する異物を捕捉するＥＧＲフィルタを備える内燃機関の排気還流装置に関する。   The present invention relates to an exhaust gas recirculation device for an internal combustion engine. More specifically, the present invention relates to an exhaust gas recirculation device for an internal combustion engine including an EGR filter that captures foreign matter flowing into an EGR passage.

従来、内燃機関の排気還流装置として、特許文献１に開示された技術がある（特許文献１参照）。
特許文献１に開示された技術では、内燃機関の排気通路に配置されたディーゼルパティキュレートフィルタ（Ｄｉｅｓｅｌ Ｐａｒｔｉｃｕｌａｔｅ Ｆｉｌｔｅｒ、以下、ＤＰＦという）よりも排気流れ方向下流側の部位から分岐し、吸気通路のコンプレッサよりも吸気流れ方向上流側の部位に合流する低圧ＥＧＲ通路を備える。そして、低圧ＥＧＲ通路の排気流れ方向上流側の部位に、低圧ＥＧＲ通路に流入するＤＰＦの欠片や金属片などの異物を捕捉するＥＧＲフィルタを配置している。 Conventionally, there is a technique disclosed in Patent Document 1 as an exhaust gas recirculation device for an internal combustion engine (see Patent Document 1).
In the technique disclosed in Patent Document 1, a compressor in an intake passage is branched from a portion downstream of a diesel particulate filter (hereinafter referred to as DPF) disposed in an exhaust passage of an internal combustion engine in an exhaust flow direction. A low-pressure EGR passage that joins a portion upstream of the intake flow direction. An EGR filter that captures foreign matters such as DPF fragments and metal pieces flowing into the low-pressure EGR passage is disposed at a portion upstream of the low-pressure EGR passage in the exhaust flow direction.

特開２０１１−２０２５３６号公報JP 2011-202536 A

ところで、ＨＣ反応物としてのタール生成物が排気中に含まれて排気通路から低圧ＥＧＲ通路に流入する。また、燃料成分として含有されたりエキゾーストマニホルドやＤＰＦから排出されたりした硫酸鉄が凝縮水に混入して排気通路からＥＧＲ通路に流入する。
タール生成物や硫酸鉄は、排気や凝縮水とともに低圧ＥＧＲ通路に流入し、低圧ＥＧＲ通路に配置された異物を捕捉するＥＧＲフィルタに堆積する。そして、タール生成物や硫酸鉄を堆積させたＥＧＲフィルタは、低圧ＥＧＲ通路を用いて排気の一部を内燃機関に還流させる際に低圧ＥＧＲ通路に圧力損失を生じさせる。 By the way, tar products as HC reactants are contained in the exhaust gas and flow into the low pressure EGR passage from the exhaust passage. Further, iron sulfate contained as a fuel component or discharged from the exhaust manifold or DPF enters the condensed water and flows into the EGR passage from the exhaust passage.
Tar products and iron sulfate flow into the low-pressure EGR passage together with the exhaust gas and condensed water, and accumulate on the EGR filter that captures foreign matter disposed in the low-pressure EGR passage. The EGR filter in which tar products and iron sulfate are deposited causes pressure loss in the low-pressure EGR passage when a part of the exhaust gas is recirculated to the internal combustion engine using the low-pressure EGR passage.

これに対し、低圧ＥＧＲ通路におけるＤＰＦ近傍の部位にＥＧＲフィルタを配置すれば、ＥＧＲフィルタに堆積したタール生成物はＤＰＦの再生制御時の熱で燃焼除去することができる。
しかしながら、ＥＧＲフィルタの位置がＤＰＦ近傍である程、排気通路を流通する凝縮水がＥＧＲフィルタに付着し易くなり、凝縮水に混入した硫酸鉄がＥＧＲフィルタに多量に堆積し易くなる。この場合には、硫酸鉄がＤＰＦの再生制御時の熱で燃焼除去できないため、多量に硫酸鉄を堆積させたＥＧＲフィルタが、低圧ＥＧＲ通路に圧力損失を生じさせる。 On the other hand, if the EGR filter is disposed in the vicinity of the DPF in the low pressure EGR passage, the tar product accumulated on the EGR filter can be burned and removed by the heat during the regeneration control of the DPF.
However, the closer the position of the EGR filter is to the DPF, the more easily the condensed water flowing through the exhaust passage adheres to the EGR filter, and the iron sulfate mixed in the condensed water easily accumulates in the EGR filter. In this case, since iron sulfate cannot be burned and removed by heat during DPF regeneration control, the EGR filter in which a large amount of iron sulfate is deposited causes pressure loss in the low-pressure EGR passage.

本発明は、上記課題を解決するものであり、その目的は、ＥＧＲフィルタからタール生成物および硫酸鉄の両方を除去可能とし、タール生成物および硫酸鉄がＥＧＲフィルタに堆積することに起因するＥＧＲ通路に生じる圧力損失を抑制することにある。   The present invention solves the above-mentioned problems, and the object thereof is to enable removal of both tar products and iron sulfate from the EGR filter, and EGR resulting from deposition of the tar product and iron sulfate on the EGR filter. The purpose is to suppress pressure loss generated in the passage.

本発明の内燃機関（例えば、後述のエンジン１）の排気還流装置（例えば、後述の低圧ＥＧＲ装置１０）は、内燃機関の排気通路（例えば、後述の排気管４）に設けられ、排気に含まれるＰＭを捕集するフィルタ（例えば、後述のＤＰＦ４２）と、前記フィルタを昇温して前記フィルタに捕集されたＰＭを燃焼除去することで前記フィルタを再生する昇温手段（例えば、後述のＤＰＦ再生制御部１０１）と、前記フィルタの排気流れ方向直後の前記排気通路と前記内燃機関の吸気通路（例えば、後述の吸気管３）とを連通することで排気の一部を前記内燃機関に還流するＥＧＲ通路（例えば、後述の低圧ＥＧＲ通路１１）と、前記ＥＧＲ通路における前記排気通路との接続部（例えば、後述の接続部９）の近傍に設けられ、前記ＥＧＲ通路に流入する異物を捕捉するＥＧＲフィルタ（例えば、後述のＥＧＲフィルタ１２）と、を備えた内燃機関の排気還流装置であって、前記ＥＧＲフィルタの排気流れ方向上流側の前記ＥＧＲ通路の壁面（例えば、後述の下面９１）、および／または、前記接続部の排気流れ方向下流側の前記排気通路の壁面には、前記フィルタを通過した排気の流れに抗する位置に、排気および排気とともに前記フィルタから流出する凝縮水が排気流れに対して跳ね返る跳ね返り面（例えば、後述の跳ね返り面１５）を設け、前記ＥＧＲフィルタは、前記跳ね返り面から跳ね返った排気および凝縮水が直接当たる位置に配置されることを特徴とする。   An exhaust gas recirculation device (for example, a low pressure EGR device 10 to be described later) of an internal combustion engine (for example, an engine 1 to be described later) of the present invention is provided in an exhaust passage (for example, an exhaust pipe 4 to be described later) of the internal combustion engine. A filter for collecting the collected PM (for example, DPF 42 described later), and a temperature raising means for regenerating the filter by heating and removing the PM collected by the filter by burning the filter (for example, described later) The DPF regeneration control unit 101) communicates with the exhaust passage immediately after the exhaust flow direction of the filter and an intake passage (for example, an intake pipe 3 described later) of the internal combustion engine, so that a part of the exhaust gas is communicated with the internal combustion engine. An EGR passage (for example, a low pressure EGR passage 11 described later) and a connection portion (for example, a connection portion 9 described later) between the EGR passage and the exhaust passage are provided in the vicinity of the EGR passage. An exhaust gas recirculation device for an internal combustion engine including an EGR filter (for example, an EGR filter 12 to be described later) that captures incoming foreign matter, and a wall surface of the EGR passage (for example, an upstream side of the EGR filter in the exhaust flow direction) On the wall surface of the exhaust passage downstream of the connecting portion and the exhaust passage in the exhaust flow direction to be described later, the exhaust gas and the exhaust gas flow out of the filter at a position against the flow of the exhaust gas that has passed through the filter. A rebound surface (for example, a rebound surface 15 described later) on which condensed water that rebounds from the exhaust flow is provided, and the EGR filter is disposed at a position where the exhaust gas and the condensed water that rebound from the rebound surface directly contact each other. And

本発明によると、ＥＧＲフィルタは、跳ね返り面から跳ね返った排気および凝縮水が直接当たる位置に配置される。このため、ＥＧＲフィルタは、跳ね返り面から跳ね返った排気および凝縮水が直接当たるようなフィルタ近傍に配置されるため、ＥＧＲフィルタに堆積するタール生成物をフィルタの再生時に燃焼除去することができる。また、ＥＧＲフィルタには、跳ね返り面から跳ね返った凝縮水が直接当たるため、フィルタ近傍に配置されたＥＧＲフィルタに堆積し易い硫酸鉄を凝縮水で洗い流して除去することができる。これによって、ＥＧＲフィルタに堆積し易い硫酸鉄をＥＧＲフィルタに所定量以上堆積させない。したがって、ＥＧＲフィルタからタール生成物および硫酸鉄の両方を除去可能とし、タール生成物および硫酸鉄がＥＧＲフィルタに堆積することに起因するＥＧＲ通路に生じる圧力損失を抑制することができる。   According to this invention, an EGR filter is arrange | positioned in the position where the exhaust and the condensed water which bounced from the bounce surface hit directly. For this reason, since the EGR filter is disposed in the vicinity of the filter so that the exhaust gas and the condensed water bounced from the rebound surface directly contact with each other, tar products accumulated on the EGR filter can be removed by combustion during regeneration of the filter. Further, since the condensed water bounced from the rebound surface directly hits the EGR filter, iron sulfate that easily accumulates on the EGR filter arranged in the vicinity of the filter can be washed away with the condensed water and removed. As a result, iron sulfate that easily deposits on the EGR filter is not deposited on the EGR filter by a predetermined amount or more. Therefore, both the tar product and iron sulfate can be removed from the EGR filter, and the pressure loss generated in the EGR passage due to the tar product and iron sulfate being deposited on the EGR filter can be suppressed.

前記ＥＧＲフィルタは、前記跳ね返り面から目視できる位置に設けられることが好ましい。   It is preferable that the EGR filter is provided at a position where the EGR filter is visible from the rebound surface.

本発明によると、ＥＧＲフィルタは、跳ね返り面から目視できる位置に設けられるため、跳ね返り面とＥＧＲフィルタとの間に障害物が無く、排気および凝縮水を跳ね返り面からＥＧＲフィルタに直接当てることができる。   According to the present invention, since the EGR filter is provided at a position where it can be seen from the rebound surface, there is no obstacle between the rebound surface and the EGR filter, and exhaust and condensed water can be directly applied to the EGR filter from the rebound surface. .

前記跳ね返り面は、前記排気通路の排気流れ方向上流側の位置から目視できる位置に設けられ、前記ＥＧＲフィルタは、前記排気通路の排気流れ方向上流側の位置から目視できない位置に設けられることが好ましい。   It is preferable that the rebound surface is provided at a position that can be viewed from an upstream position of the exhaust passage in the exhaust flow direction, and the EGR filter is provided at a position that cannot be viewed from an upstream position of the exhaust passage in the exhaust flow direction. .

本発明によると、跳ね返り面は、排気通路の排気流れ方向上流側の位置から目視できる位置に設けられるため、排気通路を流通する排気および凝縮水が跳ね返り面に直接衝突し、排気および凝縮水を跳ね返り面で跳ね返すことができる。
また、ＥＧＲフィルタは、排気通路の排気流れ方向上流側の位置から目視できない位置に設けられるため、排気通路を流通する排気がＥＧＲフィルタに直接当たり難く、排気に含まれるＨＣ反応物としてのタール生成物がＥＧＲフィルタに堆積し難くなる。 According to the present invention, the rebound surface is provided at a position where it can be seen from the position upstream of the exhaust passage in the exhaust flow direction, so that the exhaust and condensed water flowing through the exhaust passage directly collide with the rebound surface, You can bounce on the bounce surface.
In addition, since the EGR filter is provided at a position where it cannot be seen from the upstream side in the exhaust flow direction of the exhaust passage, the exhaust gas flowing through the exhaust passage hardly hits the EGR filter directly, and tar generation as an HC reactant contained in the exhaust is generated. Things are difficult to deposit on the EGR filter.

前記排気通路の排気圧を取得する排気圧取得手段（例えば、後述の排気圧センサ４４）と、前記吸気通路の吸気圧を取得する吸気圧取得手段（例えば、後述の吸気圧センサ２１）と、取得された排気圧および吸気圧に基づいて、前記ＥＧＲフィルタを含む前記ＥＧＲ通路の圧力異常が発生しているか否かを判定する第１判定手段（例えば、後述のステップＳ１，Ｓ２）と、前記第１判定手段によって圧力異常が発生していると判定されたときに、前記昇温手段を用いて前記フィルタの再生を実施し、前記フィルタの再生後に前記第１判定手段を用いて再度の判定を実施し、前記第１判定手段の再度の判定によって圧力異常が発生していると判定されたときに、前記ＥＧＲ通路に圧力異常が発生していると確定する第２判定手段（例えば、後述のステップＳ１，Ｓ２，Ｓ３，Ｓ４，Ｓ５，Ｓ６）と、を更に備えたことが好ましい。   Exhaust pressure acquisition means (for example, an exhaust pressure sensor 44 described later) for acquiring the exhaust pressure of the exhaust passage, intake pressure acquisition means (for example, an intake pressure sensor 21 described later) for acquiring the intake pressure of the intake passage, First determination means (for example, Steps S1 and S2 to be described later) for determining whether or not a pressure abnormality of the EGR passage including the EGR filter has occurred based on the acquired exhaust pressure and intake pressure; When it is determined by the first determination means that a pressure abnormality has occurred, regeneration of the filter is performed using the temperature raising means, and determination is performed again using the first determination means after regeneration of the filter. And determining that a pressure abnormality has occurred in the EGR passage when the first determination means determines again that a pressure abnormality has occurred (for example, described later) Step S1, S2, S3, S4, S5, S6) and, preferably further comprising a.

本発明によると、第１判定手段によって圧力異常が発生していると判定されたときに、昇温手段を用いてフィルタの再生を実施し、フィルタの再生後に第１判定手段を用いて再度の判定を実施する。このため、フィルタの再生の実施によりタール生成物をＥＧＲフィルタから燃焼除去することで、ＥＧＲフィルタにタール生成物が堆積したことを要因とするＥＧＲ通路の圧力異常を直ぐに解消することができる。これにより、直ぐに解消可能なＥＧＲ通路の圧力異常と、直ぐに解消できないＥＧＲ通路の圧力異常とを切り分け、直ぐに解消できないＥＧＲ通路の圧力異常を確実に発見することができる。   According to the present invention, when it is determined by the first determination means that a pressure abnormality has occurred, the regeneration of the filter is performed using the temperature raising means, and after the regeneration of the filter, the first determination means is used again. Make a decision. For this reason, the tar product is burned and removed from the EGR filter by regenerating the filter, so that the pressure abnormality in the EGR passage caused by the accumulation of the tar product on the EGR filter can be solved immediately. As a result, the pressure abnormality of the EGR passage that can be resolved immediately and the pressure abnormality of the EGR passage that cannot be resolved immediately can be separated, and the pressure abnormality of the EGR passage that cannot be resolved immediately can be reliably detected.

前記第２判定手段は、前記第１判定手段の再度の判定によって圧力異常が発生していると確定させたときは、前記ＥＧＲフィルタを除く前記ＥＧＲ通路に圧力異常が発生していると確定することが好ましい。   The second determination means determines that a pressure abnormality has occurred in the EGR passage excluding the EGR filter when it is determined that a pressure abnormality has occurred by the second determination of the first determination means. It is preferable.

本発明によると、第２判定手段は、フィルタの再生の実施によりタール生成物をＥＧＲフィルタから燃焼除去することで、ＥＧＲフィルタにタール生成物が堆積したことを要因とするＥＧＲ通路の圧力異常を直ぐに解消する。これにより、第１判定手段の再度の判定によって圧力異常が発生していると確定させたときは、ＥＧＲフィルタにタール生成物が堆積したことを要因とするＥＧＲ通路の圧力異常は生じない。その結果、第２判定手段は、異常が発生した部位を、ＥＧＲフィルタを除くＥＧＲ通路の部位であると特定することができ、異常判定の精度を向上することができる。   According to the present invention, the second determining means burns and removes the tar product from the EGR filter by performing the regeneration of the filter, thereby detecting the pressure abnormality in the EGR passage caused by the accumulation of the tar product on the EGR filter. Eliminate immediately. Thereby, when it is determined that the pressure abnormality has occurred by the second determination by the first determination means, the pressure abnormality of the EGR passage due to the accumulation of the tar product on the EGR filter does not occur. As a result, the second determination means can identify the part where the abnormality has occurred as the part of the EGR passage excluding the EGR filter, and can improve the accuracy of the abnormality determination.

前記昇温手段を用いた前回の前記フィルタの再生から、前記内燃機関が搭載された車両の走行距離または前記内燃機関の運転時間が所定値以下であるときに、前記第１判定手段によって圧力異常が発生していると判定されたときは、前記ＥＧＲ通路に圧力異常が発生していると確定する第３判定手段（例えば、後述のステップＳ３）を更に備えたことが好ましい。   When the travel distance of the vehicle on which the internal combustion engine is mounted or the operation time of the internal combustion engine is less than or equal to a predetermined value from the previous regeneration of the filter using the temperature raising means, the first determination means causes a pressure abnormality. It is preferable to further include third determination means (for example, step S3 to be described later) that determines that a pressure abnormality has occurred in the EGR passage.

前回のフィルタの再生から、内燃機関が搭載された車両の走行距離または内燃機関の運転時間が所定値以下である場合には、未だＥＧＲフィルタにはタール生成物が堆積していない。本発明によると、前回のフィルタの再生から、内燃機関が搭載された車両の走行距離または内燃機関の運転時間が所定値以下であり、未だＥＧＲフィルタにタール生成物が堆積していないと判断できる場合には、第２判定手段によるフィルタの再生を実施させず、余計なフィルタの再生を回避する。そして、余計なフィルタの再生の実施時間などを省略し、迅速にＥＧＲ通路の圧力異常を確定することができる。また、余計なフィルタの再生を回避するため、燃費や排気エミッションの悪化を抑制することができる。   If the travel distance of the vehicle on which the internal combustion engine is mounted or the operation time of the internal combustion engine is less than or equal to a predetermined value from the previous regeneration of the filter, tar products have not yet accumulated on the EGR filter. According to the present invention, from the previous regeneration of the filter, it can be determined that the travel distance of the vehicle on which the internal combustion engine is mounted or the operation time of the internal combustion engine is less than or equal to a predetermined value and that tar products are not yet accumulated on the EGR filter. In this case, the filter regeneration by the second determination unit is not performed, and unnecessary filter regeneration is avoided. Further, it is possible to quickly determine an abnormal pressure in the EGR passage by omitting an extra filter regeneration time and the like. Further, since unnecessary regeneration of the filter is avoided, it is possible to suppress deterioration of fuel consumption and exhaust emission.

本発明によれば、ＥＧＲフィルタからタール生成物および硫酸鉄の両方を除去可能とし、タール生成物および硫酸鉄がＥＧＲフィルタに堆積することに起因するＥＧＲ通路に生じる圧力損失を抑制することができる。   According to the present invention, both the tar product and iron sulfate can be removed from the EGR filter, and the pressure loss generated in the EGR passage caused by the tar product and iron sulfate being deposited on the EGR filter can be suppressed. .

本発明の実施形態に係る内燃機関を示す概略構成図である。1 is a schematic configuration diagram showing an internal combustion engine according to an embodiment of the present invention. 上記実施形態に係る排気管と低圧ＥＧＲ通路との接続部の近傍を示す図である。It is a figure which shows the vicinity of the connection part of the exhaust pipe which concerns on the said embodiment, and a low voltage | pressure EGR channel | path. 上記実施形態に係る排気管と低圧ＥＧＲ通路との接続部の近傍を示す図２のＡ−Ａ線での断面図である。It is sectional drawing in the AA line of FIG. 2 which shows the vicinity of the connection part of the exhaust pipe which concerns on the said embodiment, and a low voltage | pressure EGR channel | path. 上記実施形態に係る排気管と低圧ＥＧＲ通路との接続部の近傍を示す図２のＢ−Ｂ線での断面図である。It is sectional drawing in the BB line of FIG. 2 which shows the vicinity of the connection part of the exhaust pipe which concerns on the said embodiment, and a low voltage | pressure EGR channel | path. 上記実施形態に係る排気管と低圧ＥＧＲ通路との接続部の近傍を示す図２のＣ−Ｃ線での断面図である。It is sectional drawing in the CC line of FIG. 2 which shows the vicinity of the connection part of the exhaust pipe which concerns on the said embodiment, and a low voltage | pressure EGR channel | path. 上記実施形態に係るＤＰＦ再生制御時のタール生成物燃焼特性を示す図である。It is a figure which shows the tar product combustion characteristic at the time of DPF regeneration control which concerns on the said embodiment. 上記実施形態に係るＤＰＦ再生制御時の排気管と低圧ＥＧＲ通路との接続部の近傍の温度変化を示す図である。It is a figure which shows the temperature change of the vicinity of the connection part of the exhaust pipe and low pressure EGR channel | path at the time of DPF regeneration control which concerns on the said embodiment. 上記実施形態に係る機関運転時のＥＧＲフィルタの温度変化を示す図である。It is a figure which shows the temperature change of the EGR filter at the time of engine operation which concerns on the said embodiment. 上記実施形態に係る機関始動時の排気管と低圧ＥＧＲ通路との接続部の近傍における凝縮水の流れを示す図である。It is a figure which shows the flow of the condensed water in the vicinity of the connection part of the exhaust pipe at the time of engine starting which concerns on the said embodiment, and a low voltage | pressure EGR channel | path. 上記実施形態に係るＥＣＵによる低圧ＥＧＲ異常検知の処理手順を示すフローチャートである。It is a flowchart which shows the process sequence of the low voltage | pressure EGR abnormality detection by ECU which concerns on the said embodiment.

以下に図面を参照して本発明の実施形態を説明する。   Embodiments of the present invention will be described below with reference to the drawings.

まず、本実施形態に係る内燃機関１の構成について説明する。
図１は、本実施形態に係る内燃機関１を示す概略構成図である。 First, the configuration of the internal combustion engine 1 according to the present embodiment will be described.
FIG. 1 is a schematic configuration diagram showing an internal combustion engine 1 according to the present embodiment.

内燃機関（以下、エンジン）１は、車両に搭載され、各気筒２の燃焼室内に燃料を直接噴射するディーゼルエンジンである。エンジン１の各気筒２には、図示しない燃料噴射弁が設けられる。
エンジン１は、燃料噴射弁と電気的に接続された電子制御ユニット（以下、ＥＣＵ）１００を備える。燃料噴射弁の開弁時間および閉弁時間は、ＥＣＵ１００により制御される。 An internal combustion engine (hereinafter referred to as an engine) 1 is a diesel engine that is mounted on a vehicle and injects fuel directly into a combustion chamber of each cylinder 2. Each cylinder 2 of the engine 1 is provided with a fuel injection valve (not shown).
The engine 1 includes an electronic control unit (hereinafter, ECU) 100 that is electrically connected to a fuel injection valve. The valve opening time and valve closing time of the fuel injection valve are controlled by the ECU 100.

エンジン１は、吸気管３と、排気管４と、過給機５と、低圧ＥＧＲ装置１０と、を備える。   The engine 1 includes an intake pipe 3, an exhaust pipe 4, a supercharger 5, and a low pressure EGR device 10.

吸気管３は、吸気を流通させる吸気通路として機能し、吸気マニホールド７の複数の分岐部を介してエンジン１の各気筒２の吸気ポートに接続される。   The intake pipe 3 functions as an intake passage through which intake air flows, and is connected to the intake port of each cylinder 2 of the engine 1 via a plurality of branch portions of the intake manifold 7.

吸気管３には、吸気圧センサ３１が設けられる。
吸気圧センサ３１は、吸気管３を流通する吸気の圧力を検出する。
吸気圧センサ３１は、ＥＣＵ１００に電気的に接続され、吸気管３を流通する吸気の圧力の検出信号をＥＣＵ１００に送信する。 An intake pressure sensor 31 is provided in the intake pipe 3.
The intake pressure sensor 31 detects the pressure of intake air flowing through the intake pipe 3.
The intake pressure sensor 31 is electrically connected to the ECU 100 and transmits a detection signal of the pressure of intake air flowing through the intake pipe 3 to the ECU 100.

排気管４は、排気を流通させる排気通路として機能し、排気マニホールド８の複数の分岐部を介してエンジン１の各気筒２の排気ポートに接続される。   The exhaust pipe 4 functions as an exhaust passage through which exhaust flows, and is connected to the exhaust port of each cylinder 2 of the engine 1 through a plurality of branch portions of the exhaust manifold 8.

過給機５は、吸気を吸気管３に圧送する。
過給機５は、タービン５１と、コンプレッサ５２と、を有する。 The supercharger 5 pumps intake air to the intake pipe 3.
The supercharger 5 includes a turbine 51 and a compressor 52.

タービン５１は、排気管４の途中に配置され、排気管４を流通する排気の運動エネルギにより駆動される。
タービン５１は、図示しない複数の可変ベーンを有し、可変ベーンの開度を変化させることでタービン５１の回転速度を変更可能に構成される。可変ベーンの開度は、ＥＣＵ１００により電磁的に制御される。 The turbine 51 is disposed in the middle of the exhaust pipe 4 and is driven by the kinetic energy of the exhaust gas that flows through the exhaust pipe 4.
The turbine 51 has a plurality of variable vanes (not shown), and is configured to be able to change the rotational speed of the turbine 51 by changing the opening of the variable vanes. The opening degree of the variable vane is electromagnetically controlled by the ECU 100.

コンプレッサ５２は、吸気管３の途中に配置され、タービン５１の回転が伝達されて従動回転し、吸気を加圧して吸気管３へ圧送する。   The compressor 52 is disposed in the middle of the intake pipe 3, is rotated by the rotation of the turbine 51, pressurizes the intake air, and pumps it to the intake pipe 3.

排気管４におけるタービン５１の排気流れ方向下流側の部位には、酸化触媒４１と、ＤＰＦ４２と、が排気流れ方向上流側からこの順でケース４３（図２参照）内に設けられる。   An oxidation catalyst 41 and a DPF 42 are provided in the case 43 (see FIG. 2) in this order from the upstream side in the exhaust flow direction in a portion of the exhaust pipe 4 on the downstream side in the exhaust flow direction of the turbine 51.

酸化触媒４１は、排気や燃料との反応により発生する熱で排気を昇温する。
酸化触媒４１としては、例えば、触媒として作用する白金（Ｐｔ）を、アルミナ（Ａｌ２Ｏ３）担体に担持させたものに、ＨＣの吸着作用に優れたゼオライトと、ＨＣの水蒸気改質作用に優れたロジウム（Ｒｈ）を加えて構成されたものを用いる。 The oxidation catalyst 41 raises the temperature of the exhaust gas with heat generated by the reaction with the exhaust gas and the fuel.
As the oxidation catalyst 41, for example, platinum (Pt) acting as a catalyst is supported on an alumina (Al 2 O 3 ) carrier, zeolite having excellent HC adsorption action, and HC steam reforming action. The one composed of excellent rhodium (Rh) is used.

ＤＰＦ４２は、排気がフィルタ壁の微細な孔を通過する際に、ＰＭをフィルタ壁の表面およびフィルタ壁中の孔に堆積させることで捕集する。フィルタ壁の構成材料としては、例えば、炭化ケイ素などのセラミックスの多孔体が使用される。
ＤＰＦ４２は、捕集能力の限界すなわち堆積限界までＰＭを捕集すると排気管４の圧力損失が大きくなるため、ＤＰＦ４２に捕集したＰＭを燃焼除去させるＤＰＦ再生制御が実行される。 When the exhaust gas passes through the fine holes in the filter wall, the DPF 42 collects PM by depositing PM on the surface of the filter wall and the holes in the filter wall. As a constituent material of the filter wall, for example, a ceramic porous body such as silicon carbide is used.
When the DPF 42 collects PM up to the limit of the collection capability, that is, the accumulation limit, the pressure loss of the exhaust pipe 4 becomes large. Therefore, DPF regeneration control for burning and removing the PM collected in the DPF 42 is executed.

排気管４における酸化触媒４１の排気流れ方向下流側かつＤＰＦ４２の排気流れ方向上流側の部位には、排気圧センサ４４が設けられる。
排気圧センサ４４は、排気管４におけるＤＰＦ４２の排気流れ方向上流側の位置の圧力を検出する。
排気圧センサ４４は、ＥＣＵ１００に電気的に接続され、排気管４におけるＤＰＦ４２の排気流れ方向上流側の位置の圧力の検出信号をＥＣＵ１００に送信する。 An exhaust pressure sensor 44 is provided in a portion of the exhaust pipe 4 downstream of the oxidation catalyst 41 in the exhaust flow direction and upstream of the DPF 42 in the exhaust flow direction.
The exhaust pressure sensor 44 detects the pressure at the upstream side in the exhaust flow direction of the DPF 42 in the exhaust pipe 4.
The exhaust pressure sensor 44 is electrically connected to the ECU 100 and transmits a pressure detection signal to the ECU 100 at a position upstream of the DPF 42 in the exhaust pipe 4 in the exhaust flow direction.

低圧ＥＧＲ装置１０は、排気管４を流通する排気の一部を低圧ＥＧＲガスとしてエンジン１へ還流させる。
低圧ＥＧＲ装置１０は、低圧ＥＧＲ通路１１と、ＥＧＲフィルタ１２と、低圧ＥＧＲクーラ１３と、低圧ＥＧＲ弁１４と、を有する。 The low pressure EGR device 10 recirculates a part of the exhaust gas flowing through the exhaust pipe 4 to the engine 1 as low pressure EGR gas.
The low pressure EGR device 10 includes a low pressure EGR passage 11, an EGR filter 12, a low pressure EGR cooler 13, and a low pressure EGR valve 14.

低圧ＥＧＲ通路１１は、管状体を用いて排気管４におけるＤＰＦ４２の排気流れ方向直後の部位（コーン部４５（図２参照））と、吸気管３におけるコンプレッサ５２の上流側の部位とを連通し、ＤＰＦ４２の排気流れ方向直後の排気の一部を低圧ＥＧＲガスとして吸気管３におけるコンプレッサ５２の排気流れ方向上流側の部位に還流する。   The low-pressure EGR passage 11 communicates a portion (cone portion 45 (see FIG. 2)) immediately after the DPF 42 in the exhaust pipe 4 in the exhaust pipe 4 and a portion upstream of the compressor 52 in the intake pipe 3 using a tubular body. Then, a part of the exhaust gas immediately after the exhaust flow direction of the DPF 42 is returned to a portion of the intake pipe 3 upstream in the exhaust flow direction of the compressor 52 as low-pressure EGR gas.

ＥＧＲフィルタ１２は、低圧ＥＧＲ通路１１における排気管４との接続部９（図４参照）の近傍に設けられ、低圧ＥＧＲ通路１１に流入するＤＰＦ４２の欠片や金属片など異物を捕捉する。ＤＰＦ４２の欠片や金属片など異物が低圧ＥＧＲ通路１１を流通し、コンプレッサ５２の吸気流れ方向上流側の部位に到達すると、異物はコンプレッサ５２に流入しコンプレッサ５２を破損させるおそれがあるため、ＥＧＲフィルタ１２が配置される。   The EGR filter 12 is provided in the vicinity of the connection portion 9 (see FIG. 4) with the exhaust pipe 4 in the low pressure EGR passage 11, and captures foreign matters such as DPF 42 fragments and metal pieces flowing into the low pressure EGR passage 11. When foreign matter such as a piece of DPF 42 or a metal piece flows through the low pressure EGR passage 11 and reaches the upstream side of the compressor 52 in the intake flow direction, the foreign matter may flow into the compressor 52 and damage the compressor 52. 12 is arranged.

低圧ＥＧＲクーラ１３は、低圧ＥＧＲ通路１１を通して還流する低圧ＥＧＲガスの温度を低下させる。
低圧ＥＧＲクーラ１３は、水冷式であり、低圧ＥＧＲ通路１１を流通する低圧ＥＧＲガスとエンジン冷却水との間で熱交換をする。 The low pressure EGR cooler 13 reduces the temperature of the low pressure EGR gas that flows back through the low pressure EGR passage 11.
The low-pressure EGR cooler 13 is a water-cooled type, and exchanges heat between the low-pressure EGR gas flowing through the low-pressure EGR passage 11 and the engine coolant.

低圧ＥＧＲ弁１４は、低圧ＥＧＲ通路１１を通して還流する低圧ＥＧＲガスの流量を制御する。
低圧ＥＧＲ弁１４は、図示しないアクチュエータを介してＥＣＵ１００に接続されており、その弁開度はＥＣＵ１００により電磁的に制御される。 The low pressure EGR valve 14 controls the flow rate of the low pressure EGR gas that flows back through the low pressure EGR passage 11.
The low pressure EGR valve 14 is connected to the ECU 100 via an actuator (not shown), and the valve opening degree is electromagnetically controlled by the ECU 100.

ＥＣＵ１００は、入力回路と、中央演算処理ユニット（以下、ＣＰＵという）と、記憶回路と、出力回路と、を備える。
入力回路は、各種センサからの入力信号波形を整形し、電圧レベルを所定のレベルに修正し、アナログ信号値をデジタル信号値に変換するなどの機能を有する。
記憶回路は、ＣＰＵで実行される各種演算プログラムおよび演算結果などを記憶する。
出力回路は、低圧ＥＧＲ弁１４やエンジン１の燃料噴射弁などに制御信号を出力する。 ECU 100 includes an input circuit, a central processing unit (hereinafter referred to as CPU), a storage circuit, and an output circuit.
The input circuit has functions such as shaping input signal waveforms from various sensors, correcting a voltage level to a predetermined level, and converting an analog signal value into a digital signal value.
The storage circuit stores various calculation programs executed by the CPU, calculation results, and the like.
The output circuit outputs a control signal to the low pressure EGR valve 14 and the fuel injection valve of the engine 1.

ＥＣＵ１００は、上記のようなハードウェア構成により、ＤＰＦ再生制御部１０１と、低圧ＥＧＲ制御部１０２と、のモジュールが構成される。
以下、各モジュールの機能について説明する。 The ECU 100 includes a module including a DPF regeneration control unit 101 and a low-pressure EGR control unit 102 with the hardware configuration described above.
Hereinafter, the function of each module will be described.

ＤＰＦ再生制御部１０１は、堆積量パラメータ算出部と、フィルタリング部と、再生判定部と、再生実行部と、を含んで構成される（いずれも図示せず）。
堆積量パラメータ算出部では、ＤＰＦ４２に堆積したＰＭの堆積量の指標となる堆積量パラメータを算出する。
フィルタリング部では、堆積量パラメータ算出部により算出された堆積量パラメータに対して、フィルタリング処理を施す。
再生判定部では、フィルタリングされた堆積量パラメータに基づいてＤＰＦ再生制御を実行するか否かを判定する。
再生実行部では、ＤＰＦ再生制御を実行する。ＤＰＦ再生制御は、燃料噴射弁でポスト噴射を実行し、未燃の燃料を酸化触媒４１で燃焼させることで、ＤＰＦ４２に流入する排気を昇温させ、ＤＰＦ４２に堆積したＰＭを燃焼除去する。 The DPF regeneration control unit 101 includes a deposition amount parameter calculation unit, a filtering unit, a regeneration determination unit, and a regeneration execution unit (all not shown).
The accumulation amount parameter calculation unit calculates an accumulation amount parameter that serves as an index of the accumulation amount of PM accumulated on the DPF 42.
The filtering unit performs a filtering process on the deposition amount parameter calculated by the deposition amount parameter calculation unit.
The regeneration determination unit determines whether to execute DPF regeneration control based on the filtered accumulation amount parameter.
The regeneration executing unit executes DPF regeneration control. In the DPF regeneration control, post-injection is executed by the fuel injection valve, and unburned fuel is burned by the oxidation catalyst 41, whereby the temperature of the exhaust gas flowing into the DPF 42 is raised and PM accumulated in the DPF 42 is removed by combustion.

低圧ＥＧＲ制御部１０２は、低圧ＥＧＲ弁１４の開度を制御し、低圧ＥＧＲ通路１１を介して還流される低圧ＥＧＲガスの流量を調整し、エンジン１への排気の還流制御を行う。   The low-pressure EGR control unit 102 controls the opening degree of the low-pressure EGR valve 14, adjusts the flow rate of the low-pressure EGR gas that is recirculated through the low-pressure EGR passage 11, and controls the recirculation of the exhaust gas to the engine 1.

次に、排気管４と低圧ＥＧＲ通路１１との接続部９の近傍の詳細について説明する。
図２は、本実施形態に係る排気管４と低圧ＥＧＲ通路１１との接続部９の近傍を示す図である。図３は、本実施形態に係る排気管４と低圧ＥＧＲ通路１１との接続部９の近傍を示す図２のＡ−Ａ線での断面図である。図４は、本実施形態に係る排気管４と低圧ＥＧＲ通路１１との接続部９の近傍を示す図２のＢ−Ｂ線での断面図である。図５は、本実施形態に係る排気管４と低圧ＥＧＲ通路１１との接続部９の近傍を示す図２のＣ−Ｃ線での断面図である。 Next, details of the vicinity of the connection portion 9 between the exhaust pipe 4 and the low-pressure EGR passage 11 will be described.
FIG. 2 is a view showing the vicinity of the connection portion 9 between the exhaust pipe 4 and the low pressure EGR passage 11 according to the present embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, showing the vicinity of the connection portion 9 between the exhaust pipe 4 and the low pressure EGR passage 11 according to the present embodiment. FIG. 4 is a cross-sectional view taken along line BB in FIG. 2, showing the vicinity of the connection portion 9 between the exhaust pipe 4 and the low pressure EGR passage 11 according to the present embodiment. FIG. 5 is a cross-sectional view taken along the line CC of FIG. 2 showing the vicinity of the connection portion 9 between the exhaust pipe 4 and the low-pressure EGR passage 11 according to the present embodiment.

低圧ＥＧＲ通路１１は、図２に示すように、エンジン１の側面に沿って排気流れ方向を下向きにした排気管４におけるＤＰＦ４２の排気流れ方向直後の部位である下流側程縮径したコーン部４５に接続部９を有する。
接続部９は、コーン部４５の途中から低圧ＥＧＲ通路１１をやや上方に傾けながら横向きに延出する。
接続部９の近傍には、跳ね返り面１５と、ＥＧＲフィルタ１２と、を備える。 As shown in FIG. 2, the low-pressure EGR passage 11 has a cone portion 45 whose diameter is reduced toward the downstream side, which is a portion immediately after the exhaust flow direction of the DPF 42 in the exhaust pipe 4 with the exhaust flow direction downward along the side surface of the engine 1. Has a connecting portion 9.
The connecting portion 9 extends sideways from the middle of the cone portion 45 while tilting the low pressure EGR passage 11 slightly upward.
In the vicinity of the connecting portion 9, a rebound surface 15 and an EGR filter 12 are provided.

跳ね返り面１５は、低圧ＥＧＲ通路１１におけるＥＧＲフィルタ１２の排気流れ方向上流側の壁面であってＤＰＦ４２を通過した排気の流れに抗する位置、すなわち接続部９の下面９１に設けられ、排気および排気とともにＤＰＦ４２から流出する凝縮水を排気流れに対して跳ね返らせる（図７、図９参照）。   The rebound surface 15 is a wall surface on the upstream side in the exhaust flow direction of the EGR filter 12 in the low pressure EGR passage 11 and is provided at a position that resists the flow of exhaust gas that has passed through the DPF 42, that is, on the lower surface 91 of the connection portion 9. At the same time, the condensed water flowing out from the DPF 42 is rebounded against the exhaust flow (see FIGS. 7 and 9).

跳ね返り面１５は、図３に示すように、跳ね返り面１５の位置よりも排気流れ方向上流側の位置（図２の矢印Ｄ）から排気流れ方向下流側を見たときに、その位置と跳ね返り面１５との間に障害物が無く、目視できる。
跳ね返り面１５は、ＤＰＦ４２から流出する凝縮水を跳ね返した際に、跳ね返した凝縮水を一旦上方に飛翔させて低圧ＥＧＲ通路１１における排気流れ方向下流側（ＥＧＲフィルタ１２側）に向かわせる角度で配置される。 As shown in FIG. 3, when the rebound surface 15 is viewed from the position upstream of the rebound surface 15 in the exhaust flow direction (arrow D in FIG. 2), the position and the rebound surface. There is no obstacle between 15 and visible.
When the condensed water flowing out from the DPF 42 is rebounded, the rebound surface 15 is disposed at an angle that causes the condensate that has bounced off once to fly upward and toward the downstream side in the exhaust gas flow direction (EGR filter 12 side) in the low-pressure EGR passage 11. Is done.

ＥＧＲフィルタ１２は、図４、図５に示すように、半球状の金属メッシュ（特にはＳＵＳ材）製で形成される。
ＥＧＲフィルタ１２は、図４に示すように、半球状の凸部を上下方向に延びる排気管４に対して直交するように排気流れ方向上流側に突出させ（図７、図９参照）、跳ね返り面１５から跳ね返った排気および凝縮水が直接当たる位置に配置される。
ここで、跳ね返り面１５から跳ね返った排気および凝縮水が直接当たる位置とは、跳ね返り面１５から跳ね返って上方に飛翔した凝縮水が全体に降りかかる位置である。 As shown in FIGS. 4 and 5, the EGR filter 12 is made of a hemispherical metal mesh (particularly SUS material).
As shown in FIG. 4, the EGR filter 12 projects a hemispherical convex portion upstream in the exhaust flow direction so as to be orthogonal to the exhaust pipe 4 extending in the vertical direction (see FIGS. 7 and 9) and bounces. The exhaust and the condensed water bounced off from the surface 15 are arranged at positions where they directly hit each other.
Here, the position where the exhaust gas and the condensed water bounced from the bounce surface 15 directly hit each other is a position where the condensed water bounced off the bounce surface 15 and flew upward falls on the entire surface.

跳ね返り面１５を含む下面９１は、排気管４側を下方に傾斜させた傾斜面に構成される。   The lower surface 91 including the rebound surface 15 is configured as an inclined surface in which the exhaust pipe 4 side is inclined downward.

ＥＧＲフィルタ１２は、図５に示すように、跳ね返り面１５（図２の矢印Ｅ）から見ると、跳ね返り面１５とＥＧＲフィルタ１２との間に障害物が無く、目視できる位置に設けられる。
一方、ＥＧＲフィルタ１２は、図３に示すように、跳ね返り面１５の位置よりも排気流れ方向上流側の位置（図２の矢印Ｄ）から排気流れ方向下流側を見たときに、その位置からコーン部４５の壁面４５ａが障害物となり、目視できない。このため、ＤＰＦ４２を流通する排気がＥＧＲフィルタ１２に直接当たり難く、排気に含まれるＨＣ反応物としてのタール生成物がＥＧＲフィルタ１２に堆積し難くなる。 As shown in FIG. 5, the EGR filter 12 is provided at a position where there is no obstacle between the rebound surface 15 and the EGR filter 12 when viewed from the rebound surface 15 (arrow E in FIG. 2).
On the other hand, as shown in FIG. 3, when the EGR filter 12 is viewed from the position upstream of the rebound surface 15 in the exhaust flow direction (arrow D in FIG. 2), The wall surface 45a of the cone part 45 becomes an obstacle and cannot be visually observed. For this reason, the exhaust gas flowing through the DPF 42 does not easily hit the EGR filter 12, and the tar product as the HC reactant contained in the exhaust gas is difficult to deposit on the EGR filter 12.

次に、ＥＧＲフィルタ１２に堆積したタール生成物を燃焼除去する方法について説明する。
図６は、本実施形態に係るＤＰＦ再生制御時のタール生成物燃焼特性を示す図である。図６は、横軸に時間を示し、縦軸に温度およびタール生成物重量変化を示したグラフである。
ＤＰＦ再生制御時には、タール生成物は、図６に示すように、約１０分程度のＤＰＦ４２の再生時間を考慮して５３０℃以上に加熱されると燃焼し、完全消滅する。このため、ＥＧＲフィルタ１２に堆積したタール生成物を燃焼除去するためには、ＤＰＦ再生制御時にＥＧＲフィルタ１２が５３０℃以上に加熱される必要がある。 Next, a method for burning and removing the tar product deposited on the EGR filter 12 will be described.
FIG. 6 is a graph showing tar product combustion characteristics during DPF regeneration control according to the present embodiment. FIG. 6 is a graph showing time on the horizontal axis and temperature and tar product weight change on the vertical axis.
At the time of DPF regeneration control, as shown in FIG. 6, the tar product is burned and completely extinguished when heated to 530 ° C. or higher in consideration of the regeneration time of DPF 42 of about 10 minutes. For this reason, in order to burn and remove the tar product accumulated on the EGR filter 12, the EGR filter 12 needs to be heated to 530 ° C. or higher during the DPF regeneration control.

図７は、本実施形態に係るＤＰＦ再生制御時の排気管４と低圧ＥＧＲ通路１１との接続部の近傍の温度変化を示す図である。
ＤＰＦ再生制御時には、ＤＰＦ４２が６００℃程度に加熱されてＰＭを燃焼除去するため、接続部９の近傍では、図７に示すような温度変化が生じる。
すなわち、コーン部４５の排気流れ方向上流側の部位は、ＤＰＦ再生制御時に６００℃程度となる。コーン部４５に近接する接続部９は、ＤＰＦ再生制御時に５８０℃程度となる。ＥＧＲフィルタ１２を配置した位置は、ＤＰＦ再生制御時に５３０℃程度となる。低圧ＥＧＲ通路１１におけるＥＧＲフィルタ１２よりも排気流れ方向下流側の部位は、ＤＰＦ再生制御時に４８０℃程度となる。 FIG. 7 is a view showing a temperature change in the vicinity of the connection portion between the exhaust pipe 4 and the low-pressure EGR passage 11 during the DPF regeneration control according to the present embodiment.
At the time of DPF regeneration control, the DPF 42 is heated to about 600 ° C. and burns and removes PM, so that a temperature change as shown in FIG.
That is, the upstream portion of the cone portion 45 in the exhaust flow direction is about 600 ° C. during DPF regeneration control. The connecting portion 9 close to the cone portion 45 is about 580 ° C. during DPF regeneration control. The position where the EGR filter 12 is disposed is about 530 ° C. during DPF regeneration control. A portion of the low pressure EGR passage 11 on the downstream side of the EGR filter 12 in the exhaust flow direction is about 480 ° C. during DPF regeneration control.

図７に示すように、ＤＰＦ再生制御時にＥＧＲフィルタ１２を配置した位置が５３０℃程度に加熱される。これにより、ＥＧＲフィルタ１２に堆積したタール生成物は燃焼除去される。   As shown in FIG. 7, the position where the EGR filter 12 is arranged is heated to about 530 ° C. during the DPF regeneration control. Thereby, the tar product deposited on the EGR filter 12 is removed by combustion.

一方、ＤＰＦ再生制御時にコーン部４５に近接するＥＧＲフィルタ１２よりも排気流れ方向上流側の接続部９では、５８０℃程度に加熱される。
ＥＧＲフィルタ１２を配置した位置が６００℃を超える温度に加熱されると、ＥＧＲフィルタ１２は鋭敏化して耐食性の劣化現象を引き起こす。このため、安全性を加味してＥＧＲフィルタ１２は、ＤＰＦ再生制御時や機関運転が全負荷となる場合であっても、５５０℃以下に収まるように加熱される必要がある。
そのため、５８０℃程度に加熱されるこの部位では、上記のように弊害が生じるため、ＥＧＲフィルタ１２を配置できない。 On the other hand, in the DPF regeneration control, the connecting portion 9 upstream of the EGR filter 12 adjacent to the cone portion 45 in the exhaust flow direction is heated to about 580 ° C.
When the position where the EGR filter 12 is disposed is heated to a temperature exceeding 600 ° C., the EGR filter 12 becomes sensitized and causes a deterioration phenomenon of corrosion resistance. For this reason, in consideration of safety, the EGR filter 12 needs to be heated so as to be kept at 550 ° C. or lower even when the DPF regeneration control is performed or when the engine operation is at full load.
For this reason, the EGR filter 12 cannot be disposed at this portion heated to about 580 ° C. because the above-described adverse effects occur.

図８は、本実施形態に係る機関運転時のＥＧＲフィルタ１２の温度変化を示す図である。図８は、横軸にＥＧＲフィルタ１２の位置を基準とした現位置からの排気流れ方向上流側および下流側への距離を示し、縦軸に温度を示したグラフである。
図８に示すように、機関回転速度が２０００回転や３０００回転であり全負荷の機関運転時であっても、排気流れ方向上流側となる位置程、温度上昇する傾向が見られる。
そして、ＥＧＲフィルタ１２は、ＤＰＦ再生制御時だけでなく機関運転が、機関回転速度が２０００回転や３０００回転であり全負荷となる場合であっても、５３０℃以上５５０℃以下に加熱される。 FIG. 8 is a diagram showing a temperature change of the EGR filter 12 during engine operation according to the present embodiment. FIG. 8 is a graph in which the horizontal axis indicates the distance from the current position to the upstream and downstream sides in the exhaust flow direction with respect to the position of the EGR filter 12, and the vertical axis indicates the temperature.
As shown in FIG. 8, even when the engine speed is 2000 or 3000 rpm and the engine is operating at full load, the temperature tends to rise as the position becomes upstream in the exhaust flow direction.
The EGR filter 12 is heated to not less than 530 ° C. and not more than 550 ° C. not only at the time of DPF regeneration control but also when the engine is operating at an engine speed of 2000 or 3000 rpm and full load.

以上のように、ＥＧＲフィルタ１２は、ＤＰＦ再生制御時および機関運転が全負荷となる場合に、５３０℃以上５５０℃以下に加熱されるため、ＥＧＲフィルタ１２に堆積するタール生成物をそれらの場合に燃焼除去する。   As described above, since the EGR filter 12 is heated to 530 ° C. or more and 550 ° C. or less when the DPF regeneration control is performed and the engine operation is at full load, the tar product deposited on the EGR filter 12 is used in those cases. To burn off.

次に、ＥＧＲフィルタ１２に堆積した硫酸鉄を除去する方法について説明する。
図９は、本実施形態に係る機関始動時の排気管４と低圧ＥＧＲ通路１１との接続部９の近傍における凝縮水の流れを示す図である。
機関停止中は、機関停止後に低温化する排気中の水分が凝縮してＤＰＦ４２の内部に凝縮水が多量に保持される。このため、機関始動時に、機関始動の排気圧によってＤＰＦ４２の内部に多量に保持された凝縮水が排気流れ方向下流側に排気とともに一気に流出する。このとき、ＤＰＦ４２から多量に流出する凝縮水は、図９に示すように、排気とともに跳ね返り面１５に衝突して排気流れに対して跳ね返り、ＥＧＲフィルタ１２に直接当たる。 Next, a method for removing iron sulfate deposited on the EGR filter 12 will be described.
FIG. 9 is a view showing the flow of condensed water in the vicinity of the connection portion 9 between the exhaust pipe 4 and the low-pressure EGR passage 11 when the engine is started according to the present embodiment.
When the engine is stopped, the moisture in the exhaust gas, which is lowered in temperature after the engine is stopped, is condensed, and a large amount of condensed water is held inside the DPF 42. For this reason, at the time of starting the engine, a large amount of condensed water held inside the DPF 42 by the exhaust pressure at the start of the engine flows out together with the exhaust gas in the exhaust flow direction downstream. At this time, as shown in FIG. 9, the condensed water flowing out in a large amount from the DPF 42 collides with the rebound surface 15 together with the exhaust gas, rebounds against the exhaust flow, and directly hits the EGR filter 12.

具体的には、図３に示すように、跳ね返り面１５の位置よりも排気流れ方向上流側の位置（図２の矢印Ｄ）から排気流れ方向下流側を見たときに、その位置と跳ね返り面１５との間に障害物が無いため、排気とともに凝縮水は跳ね返り面１５に直接衝突する。   Specifically, as shown in FIG. 3, when the downstream side in the exhaust flow direction is viewed from the position upstream of the rebound surface 15 (arrow D in FIG. 2), the position and the rebound surface Since there is no obstacle between 15 and 15, the condensed water bounces back and collides directly with the surface 15.

そして、図５に示すように、跳ね返り面１５（図２の矢印Ｅ）から見ると、ＥＧＲフィルタ１２は目視できるため、跳ね返り面１５から跳ね返る凝縮水は、上方に飛翔してＥＧＲフィルタ１２の全体に直接降りかかる。
ＥＧＲフィルタ１２に直接降りかかった凝縮水は、ＥＧＲフィルタ１２から排気管４側に下方に傾斜した下面９１を流れて排気管４に再度戻って排出される。 As shown in FIG. 5, since the EGR filter 12 is visible when viewed from the rebound surface 15 (arrow E in FIG. 2), the condensed water rebounding from the rebound surface 15 flies upward and the entire EGR filter 12 is seen. Get down directly to.
The condensed water that has fallen directly on the EGR filter 12 flows through the lower surface 91 inclined downward from the EGR filter 12 toward the exhaust pipe 4 and returns to the exhaust pipe 4 to be discharged again.

以上により、機関始動時に、ＤＰＦ４２から多量の凝縮水が排気流れ方向下流側に排気とともに一気に流出すると、多量の凝縮水は跳ね返り面１５で跳ね返ってＥＧＲフィルタ１２の全体を濡らし、ＥＧＲフィルタ１２に堆積した硫酸鉄を洗い流して除去する。
これにより、機関始動ごとにＥＧＲフィルタ１２に堆積した硫酸鉄を洗い流して除去するため、硫酸鉄をＥＧＲフィルタ１２に継続的に所定量以上堆積させない。 As described above, when a large amount of condensate flows out of the DPF 42 together with the exhaust gas in the exhaust flow direction at the time of starting the engine, the large amount of condensate rebounds on the rebound surface 15 to wet the entire EGR filter 12 and accumulates on the EGR filter 12. Wash away and remove the ferrous sulfate.
Thereby, since the iron sulfate deposited on the EGR filter 12 is washed away every time the engine is started, iron sulfate is not continuously deposited on the EGR filter 12 by a predetermined amount or more.

次に、ＥＣＵ１００による低圧ＥＧＲ異常検知の制御を説明する。
図１０は、本実施形態に係るＥＣＵ１００による低圧ＥＧＲ異常検知の処理手順を示すフローチャートである。この処理は、所定の制御周期ごとに実行される。 Next, control of low pressure EGR abnormality detection by the ECU 100 will be described.
FIG. 10 is a flowchart showing a processing procedure of low-pressure EGR abnormality detection by the ECU 100 according to the present embodiment. This process is executed every predetermined control cycle.

ステップＳ１では、低圧ＥＧＲ異常検知を実施する。
低圧ＥＧＲ異常検知は、排気圧センサ４４の検出信号および吸気圧センサ３１の検出信号を用い、排気圧と吸気圧との差圧を算出する。 In step S1, low pressure EGR abnormality detection is performed.
The low-pressure EGR abnormality detection uses the detection signal of the exhaust pressure sensor 44 and the detection signal of the intake pressure sensor 31 to calculate a differential pressure between the exhaust pressure and the intake pressure.

ステップＳ２では、差圧異常が発生したか否かを判定する。
差圧異常が発生したか否かは、ステップＳ１で算出した排気圧と吸気圧との差圧が、予め定められた所定値を超える場合に差圧異常が発生したと判定する。
ステップＳ２において、差圧異常が発生したと肯定判定した場合には、ステップＳ３へ移行し、否定判定した場合には、ステップＳ９へ移行して正常であると確定する。
ここで、ステップＳ１，Ｓ２の処理が第１判定手段を構成する。 In step S2, it is determined whether a differential pressure abnormality has occurred.
Whether or not the differential pressure abnormality has occurred is determined that the differential pressure abnormality has occurred when the differential pressure between the exhaust pressure and the intake pressure calculated in step S1 exceeds a predetermined value.
In step S2, if an affirmative determination is made that a differential pressure abnormality has occurred, the process proceeds to step S3. If a negative determination is made, the process proceeds to step S9 and is determined to be normal.
Here, the process of step S1, S2 comprises a 1st determination means.

ステップＳ３では、前回のＤＰＦ再生制御から車両の走行距離が所定値以下か否かを判定する。
ステップＳ３において、前回のＤＰＦ再生制御から車両の走行距離が所定値以下であると肯定判定された場合には、ステップＳ７へ移行して異常であると確定し、さらにステップＳ８へ移行して警告ランプを点灯する。一方、否定判定した場合には、ステップＳ４へ移行する。
ここで、ステップＳ３の処理が第３判定手段を構成する。 In step S3, it is determined from the previous DPF regeneration control whether the travel distance of the vehicle is equal to or less than a predetermined value.
In step S3, when it is affirmatively determined from the previous DPF regeneration control that the travel distance of the vehicle is equal to or less than the predetermined value, the process proceeds to step S7 to determine that there is an abnormality, and further proceeds to step S8 for warning. Turn on the lamp. On the other hand, if a negative determination is made, the process proceeds to step S4.
Here, the process of step S3 constitutes a third determination unit.

ステップＳ４では、ＤＰＦ再生制御を実施する。
ＤＰＦ再生制御は、ＤＰＦ再生制御部１０１によって、燃料噴射弁でポスト噴射を実行し、未燃の燃料を酸化触媒４１で燃焼させることで、ＤＰＦ４２に流入する排気を昇温させ、ＤＰＦ４２に堆積したＰＭを燃焼除去する。このとき、ＥＧＲフィルタ１２に堆積したタール生成物も燃焼除去する。 In step S4, DPF regeneration control is performed.
In the DPF regeneration control, the DPF regeneration control unit 101 performs post injection with the fuel injection valve, and burns unburned fuel with the oxidation catalyst 41, thereby raising the temperature of the exhaust gas flowing into the DPF 42 and accumulating in the DPF 42. PM is burned off. At this time, the tar product deposited on the EGR filter 12 is also removed by combustion.

ステップＳ５では、再度の低圧ＥＧＲ異常検知を実施する。
再度の低圧ＥＧＲ異常検知は、ステップＳ１と同様に、排気圧センサ４４の検出信号および吸気圧センサ３１の検出信号を用い、排気圧と吸気圧との差圧を算出する。 In step S5, low-pressure EGR abnormality detection is performed again.
In the low pressure EGR abnormality detection again, the differential pressure between the exhaust pressure and the intake pressure is calculated using the detection signal of the exhaust pressure sensor 44 and the detection signal of the intake pressure sensor 31 as in step S1.

ステップＳ６では、差圧異常が発生したか否かを判定する。
差圧異常が発生したか否かは、ステップＳ５で算出した排気圧と吸気圧との差圧が、予め定められた所定値を超える場合に差圧異常が発生したと判定する。
ステップＳ６において、差圧異常が発生したと肯定判定した場合には、ステップＳ７へ移行して異常を確定し、さらにステップＳ８へ移行して警告ランプを点灯する。一方、否定判定した場合には、ステップＳ９へ移行して正常であると確定する。
ここで、ステップＳ５，Ｓ６の処理が第１判定手段を構成する。また、ステップＳ１，Ｓ２，Ｓ３，Ｓ４，Ｓ５，Ｓ６の処理が第２判定手段を構成する。 In step S6, it is determined whether a differential pressure abnormality has occurred.
Whether or not the differential pressure abnormality has occurred is determined that the differential pressure abnormality has occurred when the differential pressure between the exhaust pressure and the intake pressure calculated in step S5 exceeds a predetermined value.
In step S6, when an affirmative determination is made that a differential pressure abnormality has occurred, the process proceeds to step S7 to determine the abnormality, and further to step S8 to turn on the warning lamp. On the other hand, if a negative determination is made, the process proceeds to step S9 and is determined to be normal.
Here, the process of step S5, S6 comprises a 1st determination means. Moreover, the process of step S1, S2, S3, S4, S5, S6 comprises a 2nd determination means.

以上の本実施形態に係る低圧ＥＧＲ装置１０によれば、以下の効果を奏する。   According to the low pressure EGR device 10 according to the above-described embodiment, the following effects are obtained.

（１）本実施形態によると、ＥＧＲフィルタ１２は、跳ね返り面１５から跳ね返った排気および凝縮水が直接当たる位置に配置される。このため、ＥＧＲフィルタ１２は、跳ね返り面１５から跳ね返った排気および凝縮水が直接当たるようなＤＰＦ４２の近傍に配置されるため、ＥＧＲフィルタ１２に堆積するタール生成物をＤＰＦ再生制御時や機関運転が全負荷となる時に燃焼除去することができる。また、ＥＧＲフィルタ１２には、機関始動時にＤＰＦ４２の内部から多量に流出して跳ね返り面１５から跳ね返った凝縮水が直接当たるため、ＤＰＦ４２の近傍に配置されたＥＧＲフィルタ１２に堆積し易い硫酸鉄を凝縮水で洗い流して除去することができる。これによって、ＥＧＲフィルタ１２に堆積し易い硫酸鉄をＥＧＲフィルタ１２に所定量以上堆積させない。したがって、ＥＧＲフィルタ１２からタール生成物および硫酸鉄の両方を除去可能とし、タール生成物および硫酸鉄がＥＧＲフィルタ１２に堆積することに起因する低圧ＥＧＲ通路１１に生じる圧力損失を抑制することができる。   (1) According to the present embodiment, the EGR filter 12 is disposed at a position where exhaust and boiled water bounced from the bounce surface 15 directly hit. For this reason, since the EGR filter 12 is disposed in the vicinity of the DPF 42 where the exhaust gas and the condensed water bounced from the rebound surface 15 directly hit, the tar product accumulated on the EGR filter 12 is controlled during DPF regeneration control and engine operation. Combustion can be removed at full load. Further, since the condensed water that has flowed out of the DPF 42 and bounced off the rebound surface 15 directly hits the EGR filter 12 when the engine is started, iron sulfate that easily accumulates on the EGR filter 12 disposed in the vicinity of the DPF 42 is used. It can be removed by washing away with condensed water. As a result, iron sulfate that easily deposits on the EGR filter 12 is not deposited on the EGR filter 12 by a predetermined amount or more. Therefore, both the tar product and iron sulfate can be removed from the EGR filter 12, and the pressure loss generated in the low pressure EGR passage 11 due to the tar product and iron sulfate being deposited on the EGR filter 12 can be suppressed. .

（２）本実施形態によると、ＥＧＲフィルタ１２は、跳ね返り面１５（図２の矢印Ｅ）から目視できる位置に設けられるため、跳ね返り面１５とＥＧＲフィルタ１２との間に障害物が無く、排気および凝縮水を跳ね返り面１５からＥＧＲフィルタ１２に直接当てることができる。   (2) According to this embodiment, since the EGR filter 12 is provided at a position where it can be seen from the rebound surface 15 (arrow E in FIG. 2), there is no obstacle between the rebound surface 15 and the EGR filter 12, and the exhaust gas is exhausted. The condensed water can be directly applied to the EGR filter 12 from the rebound surface 15.

（３）本実施形態によると、跳ね返り面１５は、跳ね返り面１５の位置よりも排気流れ方向上流側の位置（図２の矢印Ｄ）から目視できる位置に設けられるため、排気管４を流通する排気および凝縮水が跳ね返り面１５に直接衝突し、排気および凝縮水を跳ね返り面１５で跳ね返すことができる。
また、ＥＧＲフィルタ１２は、跳ね返り面１５の位置よりも排気流れ方向上流側の位置（図２の矢印Ｄ）から目視できない位置に設けられるため、ＤＰＦ４２から流出する排気がＥＧＲフィルタ１２に直接当たり難く、排気に含まれるＨＣから生成されるタール生成物がＥＧＲフィルタ１２に堆積し難くなる。 (3) According to the present embodiment, the rebound surface 15 is provided at a position that can be seen from the position upstream of the position of the rebound surface 15 in the exhaust flow direction (arrow D in FIG. 2), and therefore flows through the exhaust pipe 4. The exhaust gas and the condensed water can directly collide with the rebound surface 15, and the exhaust gas and the condensed water can be rebound at the rebound surface 15.
Further, since the EGR filter 12 is provided at a position where it cannot be seen from the position upstream of the rebound surface 15 in the exhaust flow direction (arrow D in FIG. 2), the exhaust gas flowing out from the DPF 42 is difficult to directly hit the EGR filter 12. The tar product generated from the HC contained in the exhaust gas is difficult to deposit on the EGR filter 12.

（４）本実施形態によると、ステップＳ１，Ｓ２の処理によって圧力異常が発生していると判定されたときに、ステップＳ４の処理によってＤＰＦ再生制御を実施し、ＤＰＦ再生制御後にステップＳ５，Ｓ６の処理によって再度の判定を実施する。このため、ステップＳ４の処理でのＤＰＦ再生制御の実施によりタール生成物をＥＧＲフィルタ１２から燃焼除去することで、ＥＧＲフィルタ１２にタール生成物が堆積したことを要因とする低圧ＥＧＲ通路１１の圧力異常を直ぐに解消することができる。これにより、直ぐに解消可能な低圧ＥＧＲ通路１１の圧力異常と、直ぐに解消できない低圧ＥＧＲ通路１１の圧力異常とを切り分け、直ぐに解消できない低圧ＥＧＲ通路１１の圧力異常を確実に発見することができる。   (4) According to the present embodiment, when it is determined that the pressure abnormality has occurred in the processes of steps S1 and S2, the DPF regeneration control is performed by the process of step S4, and the steps S5 and S6 are performed after the DPF regeneration control. The determination is performed again by the above process. For this reason, the pressure of the low pressure EGR passage 11 caused by the tar product accumulated on the EGR filter 12 by burning and removing the tar product from the EGR filter 12 by performing the DPF regeneration control in the process of step S4. Abnormalities can be resolved immediately. Thereby, the pressure abnormality of the low-pressure EGR passage 11 that can be resolved immediately and the pressure abnormality of the low-pressure EGR passage 11 that cannot be resolved immediately can be separated, and the pressure abnormality of the low-pressure EGR passage 11 that can not be solved immediately can be reliably detected.

（５）本実施形態によると、ステップＳ４の処理によってＤＰＦ再生制御の実施によりタール生成物をＥＧＲフィルタ１２から燃焼除去することで、ＥＧＲフィルタ１２にタール生成物が堆積したことを要因とする低圧ＥＧＲ通路１１の圧力異常を直ぐに解消する。これにより、ステップＳ５，Ｓ６の処理の再度の判定によって圧力異常が発生していると確定させたときは、ＥＧＲフィルタ１２にタール生成物が堆積したことを要因とする低圧ＥＧＲ通路１１の圧力異常は生じない。その結果、ステップＳ６の処理では、異常が発生した部位を、ＥＧＲフィルタ１２を除く低圧ＥＧＲ通路１１の部位であると特定することができ、異常判定の精度を向上することができる。   (5) According to the present embodiment, the tar product is burned and removed from the EGR filter 12 by performing the DPF regeneration control in the process of step S4, so that the low pressure caused by the tar product accumulated on the EGR filter 12 is a factor. The pressure abnormality in the EGR passage 11 is immediately resolved. As a result, when it is determined that a pressure abnormality has occurred by re-determining the processing in steps S5 and S6, the pressure abnormality in the low-pressure EGR passage 11 caused by the accumulation of tar products on the EGR filter 12 is caused. Does not occur. As a result, in the process of step S6, the part where the abnormality has occurred can be identified as the part of the low pressure EGR passage 11 excluding the EGR filter 12, and the accuracy of abnormality determination can be improved.

（６）前回のＤＰＦ再生制御から、エンジン１が搭載された車両の走行距離が所定値以下である場合には、未だＥＧＲフィルタ１２にはタール生成物が堆積していない。本実施形態によると、ステップＳ３の処理によって、前回のＤＰＦ再生制御から、エンジン１が搭載された車両の走行距離が所定値以下であり、未だＥＧＲフィルタ１２にタール生成物が堆積していないと判断できる場合には、ステップＳ４によるＤＰＦ再生制御を実施させず、余計なＤＰＦ再生制御を回避する。そして、余計なＤＰＦ再生制御の実施時間などを省略し、ステップＳ７に移行して迅速に低圧ＥＧＲ通路１１の圧力異常を確定することができる。また、余計なＤＰＦ再生制御を回避するため、燃費や排気エミッションの悪化を抑制することができる。   (6) From the previous DPF regeneration control, when the travel distance of the vehicle on which the engine 1 is mounted is equal to or less than the predetermined value, the tar product has not yet accumulated on the EGR filter 12. According to the present embodiment, when the travel distance of the vehicle on which the engine 1 is mounted is less than or equal to a predetermined value and the tar product has not yet accumulated on the EGR filter 12 from the previous DPF regeneration control by the process of step S3. If it can be determined, the DPF regeneration control in step S4 is not performed, and unnecessary DPF regeneration control is avoided. Then, unnecessary time for performing the DPF regeneration control or the like is omitted, and the process proceeds to step S7, where the pressure abnormality in the low pressure EGR passage 11 can be quickly determined. Moreover, since unnecessary DPF regeneration control is avoided, deterioration of fuel consumption and exhaust emission can be suppressed.

なお、本発明は上記実施形態に限定されず、本発明の目的を達成できる範囲で変形、改良などを行っても、本発明の範囲に包含される。   Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the scope of the present invention.

本実施形態では、跳ね返り面１５を、低圧ＥＧＲ通路１１におけるＥＧＲフィルタ１２の排気流れ方向上流側の壁面である下面９１に設けたが、これに限られない。例えば、跳ね返り面１５は、接続部９における排気流れ方向下流側の排気管４の壁面などに設けられるものであってもよい。   In the present embodiment, the rebound surface 15 is provided on the lower surface 91 that is the wall surface on the upstream side in the exhaust flow direction of the EGR filter 12 in the low pressure EGR passage 11, but is not limited thereto. For example, the rebound surface 15 may be provided on the wall surface of the exhaust pipe 4 on the downstream side in the exhaust flow direction at the connection portion 9.

本実施形態では、排気圧センサ４４によって排気圧を検出し、吸気圧センサ３１によって吸気圧を検出していたが、これに限られない。例えば、排気圧や吸気圧は、演算によって推定されるものであってもよい。   In the present embodiment, the exhaust pressure sensor 44 detects the exhaust pressure and the intake pressure sensor 31 detects the intake pressure. However, the present invention is not limited to this. For example, the exhaust pressure and the intake pressure may be estimated by calculation.

本実施形態では、ステップＳ３において、前回のＤＰＦ再生制御から、エンジン１が搭載された車両の走行距離が所定値以下であり、未だＥＧＲフィルタ１２にタール生成物が堆積していないと判断できる場合には、ステップＳ４によるＤＰＦ再生制御を実施させなかった。しかし、これに限られない。例えば、ステップＳ３において、前回のＤＰＦ再生制御から、エンジン１の運転時間が所定値以下であり、未だＥＧＲフィルタ１２にタール生成物が堆積していないと判断できる場合には、同様にステップＳ４によるＤＰＦ再生制御を実施させないものであってもよい。   In the present embodiment, in step S3, it can be determined from the previous DPF regeneration control that the travel distance of the vehicle on which the engine 1 is mounted is equal to or less than a predetermined value, and the tar product has not yet accumulated on the EGR filter 12. The DPF regeneration control in step S4 was not performed. However, it is not limited to this. For example, in step S3, when it can be determined from the previous DPF regeneration control that the operation time of the engine 1 is less than or equal to a predetermined value and the tar product has not yet accumulated on the EGR filter 12, the same processing is performed in step S4. The DPF regeneration control may not be performed.

１…エンジン（内燃機関）
３…吸気管（吸気通路）
４…排気管（排気通路）
９…接続部
１０…低圧ＥＧＲ装置（排気還流装置）
１１…低圧ＥＧＲ通路（ＥＧＲ通路）
１２…ＥＧＲフィルタ
１５…跳ね返り面
２１…吸気圧センサ（吸気圧取得手段）
４２…ＤＰＦ（フィルタ）
４４…排気センサ（排気圧取得手段）
９１…下面（壁面）
１０１…ＤＰＦ再生制御部（昇温手段）
Ｓ１，Ｓ２…（第１判定手段）
Ｓ５，Ｓ６…（第１判定手段）
Ｓ１，Ｓ２，Ｓ３，Ｓ４，Ｓ５，Ｓ６…（第２判定手段）
Ｓ３…（第３判定手段） 1. Engine (internal combustion engine)
3 ... Intake pipe (intake passage)
4 ... Exhaust pipe (exhaust passage)
9 ... Connection 10 ... Low pressure EGR device (exhaust gas recirculation device)
11 ... Low pressure EGR passage (EGR passage)
DESCRIPTION OF SYMBOLS 12 ... EGR filter 15 ... Rebound surface 21 ... Intake pressure sensor (intake pressure acquisition means)
42 ... DPF (filter)
44. Exhaust sensor (exhaust pressure acquisition means)
91 ... Lower surface (wall surface)
101 ... DPF regeneration control unit (temperature raising means)
S1, S2 (first determination means)
S5, S6 (first determination means)
S1, S2, S3, S4, S5, S6 (second determination means)
S3 (third determination means)

Claims (6)

内燃機関の排気通路に設けられ、排気に含まれるＰＭを捕集するフィルタと、
前記フィルタを昇温して前記フィルタに捕集されたＰＭを燃焼除去することで前記フィルタを再生する昇温手段と、
前記フィルタの排気流れ方向直後の前記排気通路と前記内燃機関の吸気通路とを連通することで排気の一部を前記内燃機関に還流するＥＧＲ通路と、
前記ＥＧＲ通路における前記排気通路との接続部の近傍に設けられ、前記ＥＧＲ通路に流入する異物を捕捉するＥＧＲフィルタと、を備えた内燃機関の排気還流装置であって、
前記ＥＧＲフィルタの排気流れ方向上流側の前記ＥＧＲ通路の壁面、および／または、前記接続部の排気流れ方向下流側の前記排気通路の壁面には、前記フィルタを通過した排気の流れに抗する位置に、排気および排気とともに前記フィルタから流出する凝縮水が排気流れに対して跳ね返る跳ね返り面を設け、
前記ＥＧＲフィルタは、前記跳ね返り面から跳ね返った排気および凝縮水が直接当たる位置に配置されることを特徴とする内燃機関の排気還流装置。 A filter provided in the exhaust passage of the internal combustion engine for collecting PM contained in the exhaust;
A temperature raising means for regenerating the filter by heating and removing the PM collected by the filter by heating the filter;
An EGR passage that recirculates part of the exhaust to the internal combustion engine by communicating the exhaust passage immediately after the exhaust flow direction of the filter with the intake passage of the internal combustion engine;
An exhaust gas recirculation device for an internal combustion engine, comprising: an EGR filter provided in the vicinity of a connection portion of the EGR passage with the exhaust passage and capturing foreign matter flowing into the EGR passage,
The wall surface of the EGR passage on the upstream side in the exhaust flow direction of the EGR filter and / or the wall surface of the exhaust passage on the downstream side in the exhaust flow direction of the connecting portion is positioned against the flow of exhaust gas that has passed through the filter. And a rebound surface on which the condensed water flowing out of the filter together with the exhaust gas rebounds against the exhaust flow,
The exhaust gas recirculation device for an internal combustion engine, wherein the EGR filter is disposed at a position where exhaust gas and condensed water bounced from the rebound surface directly contact each other. 前記ＥＧＲフィルタは、前記跳ね返り面から目視できる位置に設けられることを特徴とする請求項１記載の内燃機関の排気還流装置。   2. The exhaust gas recirculation device for an internal combustion engine according to claim 1, wherein the EGR filter is provided at a position where the EGR filter can be seen from the rebound surface. 前記跳ね返り面は、前記排気通路の排気流れ方向上流側の位置から目視できる位置に設けられ、
前記ＥＧＲフィルタは、前記排気通路の排気流れ方向上流側の位置から目視できない位置に設けられることを特徴とする請求項２記載の内燃機関の排気還流装置。 The rebound surface is provided at a position that can be seen from a position upstream of the exhaust passage in the exhaust flow direction,
3. The exhaust gas recirculation device for an internal combustion engine according to claim 2, wherein the EGR filter is provided at a position where it cannot be seen from a position upstream of the exhaust passage in the exhaust flow direction. 前記排気通路の排気圧を取得する排気圧取得手段と、
前記吸気通路の吸気圧を取得する吸気圧取得手段と、
取得された排気圧および吸気圧に基づいて、前記ＥＧＲフィルタを含む前記ＥＧＲ通路の圧力異常が発生しているか否かを判定する第１判定手段と、
前記第１判定手段によって圧力異常が発生していると判定されたときに、前記昇温手段を用いて前記フィルタの再生を実施し、前記フィルタの再生後に前記第１判定手段を用いて再度の判定を実施し、前記第１判定手段の再度の判定によって圧力異常が発生していると判定されたときに、前記ＥＧＲ通路に圧力異常が発生していると確定する第２判定手段と、を更に備えたことを特徴とする請求項１から３のいずれか記載の内燃機関の排気還流装置。 Exhaust pressure acquisition means for acquiring the exhaust pressure of the exhaust passage;
Intake pressure acquisition means for acquiring the intake pressure of the intake passage;
First determination means for determining whether a pressure abnormality of the EGR passage including the EGR filter has occurred based on the acquired exhaust pressure and intake pressure;
When it is determined by the first determination means that a pressure abnormality has occurred, regeneration of the filter is performed using the temperature raising means, and after the regeneration of the filter, the first determination means is used again. A second determination unit that performs a determination and determines that a pressure abnormality has occurred in the EGR passage when it is determined that a pressure abnormality has occurred by the second determination of the first determination unit; The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 3, further comprising: 前記第２判定手段は、前記第１判定手段の再度の判定によって圧力異常が発生していると確定させたときは、前記ＥＧＲフィルタを除く前記ＥＧＲ通路に圧力異常が発生していると確定することを特徴とする請求項４記載の内燃機関の排気還流装置。   The second determination means determines that a pressure abnormality has occurred in the EGR passage excluding the EGR filter when it is determined that a pressure abnormality has occurred by the second determination of the first determination means. The exhaust gas recirculation device for an internal combustion engine according to claim 4. 前記昇温手段を用いた前回の前記フィルタの再生から、前記内燃機関が搭載された車両の走行距離または前記内燃機関の運転時間が所定値以下であるときに、前記第１判定手段によって圧力異常が発生していると判定されたときは、前記ＥＧＲ通路に圧力異常が発生していると確定する第３判定手段を更に備えたことを特徴とする請求項４または５記載の内燃機関の排気還流装置。   When the travel distance of the vehicle on which the internal combustion engine is mounted or the operation time of the internal combustion engine is less than or equal to a predetermined value from the previous regeneration of the filter using the temperature raising means, the first determination means causes a pressure abnormality. 6. The exhaust of an internal combustion engine according to claim 4, further comprising a third determination means for determining that a pressure abnormality has occurred in the EGR passage when it is determined that the EGR has occurred. Reflux apparatus.
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