JP6705294B2 - Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine - Google Patents

Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine Download PDF

Info

Publication number
JP6705294B2
JP6705294B2 JP2016111805A JP2016111805A JP6705294B2 JP 6705294 B2 JP6705294 B2 JP 6705294B2 JP 2016111805 A JP2016111805 A JP 2016111805A JP 2016111805 A JP2016111805 A JP 2016111805A JP 6705294 B2 JP6705294 B2 JP 6705294B2
Authority
JP
Japan
Prior art keywords
exhaust gas
passage
exhaust
internal combustion
combustion engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
JP2016111805A
Other languages
Japanese (ja)
Other versions
JP2017218913A (en
Inventor
弘吉 前川
弘吉 前川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Isuzu Motors Ltd
Original Assignee
Isuzu Motors Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Isuzu Motors Ltd filed Critical Isuzu Motors Ltd
Priority to JP2016111805A priority Critical patent/JP6705294B2/en
Publication of JP2017218913A publication Critical patent/JP2017218913A/en
Application granted granted Critical
Publication of JP6705294B2 publication Critical patent/JP6705294B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Landscapes

  • Exhaust Gas After Treatment (AREA)

Description

本発明は、内燃機関の排気ガス浄化システム及び内燃機関の排気ガス浄化方法に関する。 The present invention relates to an exhaust gas purification system for an internal combustion engine and an exhaust gas purification method for an internal combustion engine.

排気管をＳＣＲＦ（ＳＣＲをコートとしたフィルタ）とＳＣＲ（選択的触媒還元方式の触媒）との間で分岐させ、この分岐管に排気制御弁及び冷却素子を備えて、排気を冷却する必要がある場合には、目標触媒温度に応じて、分岐管を通過する排気の量を増加させて、ＳＣＲに流入する排気の温度を制御する内燃機関の排気浄化システムが提案されている（例えば、特許文献１参照）。 It is necessary to branch the exhaust pipe between SCRF (filter coated with SCR) and SCR (catalyst of selective catalytic reduction system), and to provide an exhaust control valve and a cooling element in this branch pipe to cool the exhaust gas. In some cases, an exhaust gas purification system for an internal combustion engine has been proposed which controls the temperature of the exhaust gas flowing into the SCR by increasing the amount of the exhaust gas passing through the branch pipe according to the target catalyst temperature (for example, patents). Reference 1).

特開２０１５−８６８４８号公報JP, 2005-86848, A

ところで、上記の排気浄化システムでは、ＳＣＲより下流側の排気管に流出する（スリップする）アンモニアの量を考慮して、還元剤噴射弁よりＳＣＲＦ及びＳＣＲに供給する尿素水の量を設定した使用条件においても、ＳＣＲ温度が急激に上昇した場合や、急な昇温でなくても、ＳＣＲに吸蔵しているアンモニア量がＳＣＲのアンモニア吸蔵キャパシティを超える温度に達した時にアンモニアがスリップしてしまう。そのため、ＳＣＲより下流側にアンモニアスリップ触媒装置を備えて、このアンモニアスリップ触媒装置によりＳＣＲからスリップしたアンモニアを窒素に浄化する必要があるが、この浄化反応の副生成物として窒素酸化物（ＮＯｘ）を生成することがあり、排気ガス浄化システム全体でのＮＯｘ浄化性能が低下してしまう問題があった。 By the way, in the above exhaust gas purification system, the amount of urea water supplied from the reducing agent injection valve to the SCRF and SCR is set in consideration of the amount of ammonia that flows out (slips) to the exhaust pipe downstream of the SCR. Even under the conditions, the ammonia slips when the SCR temperature rises rapidly or when the amount of ammonia stored in the SCR exceeds the ammonia storage capacity of the SCR even if the temperature does not rise suddenly. I will end up. Therefore, it is necessary to provide an ammonia slip catalyst device on the downstream side of the SCR and purify the ammonia slipped from the SCR to nitrogen by this ammonia slip catalyst device. However, nitrogen oxide (NOx) is a by-product of this purification reaction. However, there is a problem in that the NOx purification performance of the entire exhaust gas purification system deteriorates.

本発明の目的は、選択還元型触媒装置からのアンモニアスリップを抑制しつつ、排気ガス浄化システム全体でのＮＯｘ浄化性能を維持することができる内燃機関の排気ガス浄化システム及び内燃機関の排気ガス浄化方法を提供することにある。 An object of the present invention is to suppress the ammonia slip from the selective reduction catalyst device, while maintaining the NOx purification performance of the entire exhaust gas purification system, the exhaust gas purification system of the internal combustion engine and the exhaust gas purification of the internal combustion engine. To provide a method.

上記の目的を達成するための本発明の内燃機関の排気ガス浄化システムは、内燃機関の排気通路に上流側より順に尿素水供給装置、選択還元型触媒装置を備えて構成される内燃機関の排気ガス浄化システムにおいて、前記尿素水供給装置より上流側の前記排気通路に、排気ガス冷却装置を有する分岐通路を前記排気通路に並行して備えて、前記分岐通路の分岐点に流路切替装置を備えるとともに、前記選択還元型触媒装置の内部、または、前記選択還元型触媒装置の上流側または下流側の前記排気通路に温度検出装置を備え、前記選択還元型触媒装置の下流側の前記排気通路にアンモニア濃度検出装置を備えて、前記排気ガス浄化システムを制御する制御装置が、前記温度検出装置の検出値が予め設定された冷却開始温度閾値以上となったときに、または、前記アンモニア濃度検出装置の検出値が予め設定された冷却開始濃度閾値以上となったときに、前記流路切替装置を制御して、排気ガスの流れを前記排気通路から前記分岐通路に切り替える制御を行うように構成される。 An exhaust gas purifying system for an internal combustion engine according to the present invention to achieve the above object, an exhaust gas of an internal combustion engine configured to include a urea water supply device and a selective reduction catalyst device in the exhaust passage of the internal combustion engine in this order from the upstream side. In the gas purification system, a branch passage having an exhaust gas cooling device is provided in the exhaust passage upstream of the urea water supply device in parallel with the exhaust passage, and a passage switching device is provided at a branch point of the branch passage. In addition, a temperature detecting device is provided inside the selective reduction catalyst device or in the exhaust passage upstream or downstream of the selective reduction catalyst device, and the exhaust passage downstream of the selective reduction catalyst device. When the control device for controlling the exhaust gas purification system is equipped with an ammonia concentration detection device, the detected value of the temperature detection device becomes equal to or higher than a preset cooling start temperature threshold value, or the ammonia concentration detection device When the detection value of the device is equal to or higher than a preset cooling start concentration threshold value, the flow passage switching device is controlled to control the flow of exhaust gas from the exhaust passage to the branch passage. To be done.

また、上記の目的を達成するための本発明の内燃機関の排気ガス浄化方法は、内燃機関の排気通路に上流側より順に尿素水供給装置、選択還元型触媒装置を備えるとともに、前記尿素水供給装置より上流側の前記排気通路に、排気ガス冷却装置を有する分岐通路を前記排気通路に並行して備えて、前記分岐通路の分岐点に流路切替装置を備えて構成される内燃機関の排気ガス浄化方法において、前記選択還元型触媒装置の温度が予め設定された冷却開始温度閾値以上となったときに、または、前記選択還元型触媒装置より下流側の前記排気通路を通過する排気ガスのアンモニア濃度が予め設定された冷却開始濃度閾値以上となったときに、前記流路切替装置を制御して、排気ガスの流れを前記排気通路から前記分岐通路に切り替えることを特徴とする方法である。 Further, an exhaust gas purifying method for an internal combustion engine according to the present invention for achieving the above object, comprises a urea water supply device and a selective reduction type catalyst device in the exhaust passage of the internal combustion engine in this order from the upstream side. Exhaust of an internal combustion engine configured such that a branch passage having an exhaust gas cooling device is provided in the exhaust passage upstream of the device in parallel with the exhaust passage, and a flow path switching device is provided at a branch point of the branch passage. In the gas purification method, when the temperature of the selective reduction catalyst device is equal to or higher than a preset cooling start temperature threshold value, or of the exhaust gas passing through the exhaust passage on the downstream side of the selective reduction catalyst device. When the ammonia concentration exceeds a preset cooling start concentration threshold value, the flow passage switching device is controlled to switch the flow of exhaust gas from the exhaust passage to the branch passage. ..

本発明の内燃機関の排気ガス浄化システム及び内燃機関の排気ガス浄化方法によれば、選択還元型触媒装置からのアンモニアスリップを抑制しつつ、排気ガス浄化システム全体でのＮＯｘ浄化性能を維持することができる。 According to the exhaust gas purification system for an internal combustion engine and the exhaust gas purification method for an internal combustion engine of the present invention, NOx purification performance of the entire exhaust gas purification system is maintained while suppressing ammonia slip from the selective reduction catalyst device. You can

本発明の内燃機関の排気ガス浄化システムの構成を示す図である。It is a figure which shows the structure of the exhaust gas purification system of the internal combustion engine of this invention. 選択還元型触媒装置の温度とアンモニア吸蔵容量及びＮＯｘ浄化率の関係を示す図である。It is a figure which shows the temperature of a selective catalytic reduction apparatus, and the relationship of ammonia storage capacity and NOx purification rate. 本発明の内燃機関の排気ガス浄化方法の制御フローを示す図である。It is a figure which shows the control flow of the exhaust gas purification method of the internal combustion engine of this invention. 従来技術の内燃機関の排気ガス浄化システムの構成を示す図である。It is a figure which shows the structure of the exhaust gas purification system of the internal combustion engine of a prior art.

以下、本発明に係る実施形態の内燃機関の排気ガス浄化システム及び内燃機関の排気ガス浄化方法について、図面を参照しながら説明する。 Hereinafter, an exhaust gas purification system for an internal combustion engine and an exhaust gas purification method for an internal combustion engine according to embodiments of the present invention will be described with reference to the drawings.

図１に示すように、本発明の排気ガス浄化システム１は、エンジン２の排気通路（排気管）１０に上流側より順に酸化触媒装置（ＤＯＣ）１１、微粒子捕集装置１２、尿素水供給装置１５、選択還元型触媒装置（ＳＣＲ）１３を備えて構成されるシステムである。 As shown in FIG. 1, an exhaust gas purification system 1 of the present invention includes an oxidation catalyst device (DOC) 11, a fine particle collection device 12, and a urea water supply device in an exhaust passage (exhaust pipe) 10 of an engine 2 in order from an upstream side. This is a system that is equipped with a selective reduction catalyst device (SCR) 13.

酸化触媒装置１１は、ハニカム構造を形成する基材に、排気ガスＧの炭化水素（ＨＣ）や一酸化炭素（ＣＯ）等を酸化する貴金属触媒（酸化触媒）が担持されて構成される。貴金属触媒としては、炭化水素を水と二酸化炭素に、一酸化炭素を二酸化炭素にそれぞれ酸化する白金（Ｐｔ）系の触媒が好ましい。 The oxidation catalyst device 11 is configured such that a base material forming a honeycomb structure carries a noble metal catalyst (oxidation catalyst) that oxidizes hydrocarbons (HC) and carbon monoxide (CO) of the exhaust gas G. As the noble metal catalyst, a platinum (Pt)-based catalyst that oxidizes hydrocarbon into water and carbon dioxide and carbon monoxide into carbon dioxide is preferable.

この貴金属触媒による炭化水素及び一酸化炭素の酸化反応は発熱反応であるので、この発熱により排気ガスＧは昇温する。これを利用して、微粒子捕集装置１２の強制ＰＭ再生制御時等、高温の排気ガスＧが必要となるときには、酸化触媒装置１１より上流側の排気通路１０を通過する排気ガスＧに含まれる炭化水素の量を一時的に増加させて、この増加分の炭化水素を酸化触媒装置１１で酸化させることで、排気ガスＧを高温化している。 Since the oxidation reaction of hydrocarbons and carbon monoxide by this noble metal catalyst is an exothermic reaction, the exhaust gas G rises in temperature due to this heat generation. Utilizing this, when a high temperature exhaust gas G is required, such as during forced PM regeneration control of the particulate matter collection device 12, it is included in the exhaust gas G passing through the exhaust passage 10 on the upstream side of the oxidation catalyst device 11. The exhaust gas G is heated to a high temperature by temporarily increasing the amount of hydrocarbons and oxidizing the increased amount of hydrocarbons by the oxidation catalyst device 11.

なお、炭化水素の量を一時的に増加させる方法としては、例えば、エンジン２の気筒（シリンダ）２ａ内で燃料のポスト噴射を行う方法や、酸化触媒装置１１より上流側の排気通路１０に燃料噴射装置（図示しない）を備えて、この燃料噴射装置から燃料を噴射する方法がある。 As a method of temporarily increasing the amount of hydrocarbons, for example, a method of performing post-injection of fuel in the cylinder (cylinder) 2a of the engine 2 or a method of supplying fuel to the exhaust passage 10 on the upstream side of the oxidation catalyst device 11 is performed. There is a method of injecting fuel from this fuel injection device by providing an injection device (not shown).

微粒子捕集装置１２は、排気ガスＧ中の粒子状物質（ＰＭ）を捕集するために、その内部にフィルタを備えて構成される。このフィルタは、多孔質のセラミックのハニカムのセル（チャンネル）の入口と出口を交互に目封じしたモノリスハニカム型ウォールフロータイプのフィルタである。 The particulate matter collecting device 12 is configured to include a filter therein to collect the particulate matter (PM) in the exhaust gas G. This filter is a monolith honeycomb type wall flow type filter in which the inlets and outlets of cells (channels) of a porous ceramic honeycomb are alternately plugged.

排気ガスＧは、微粒子捕集装置１２の目封じされていないセルの入口より流入し、隣接する目封じされていないセルとの境界に形成されたＰＭ捕集用の壁を通過した後、目封じされていないセルの出口より流出する。排気ガスＧに含まれるＰＭはＰＭ捕集用の壁で捕集されるが、捕集量には限界がある。したがって、ＰＭ捕集量が限界値に到達する前に、微粒子捕集装置１２の内部に高温の排気ガスＧを通過させて、この排気ガスＧの熱により微粒子捕集装置１２の内部に捕集されたＰＭを燃焼除去する強制ＰＭ再生制御を定期的に行っている。 Exhaust gas G flows in from the inlet of the unplugged cell of the particulate collection device 12, passes through the PM trapping wall formed at the boundary with the adjacent unplugged cell, and It flows out from the outlet of an unsealed cell. The PM contained in the exhaust gas G is collected by the PM collection wall, but the collection amount is limited. Therefore, before the amount of collected PM reaches the limit value, the high temperature exhaust gas G is passed through the inside of the particulate collection device 12, and the heat of the exhaust gas G collects inside the particulate collection device 12. The forced PM regeneration control for burning and removing the generated PM is regularly performed.

選択還元型触媒装置１３は、その前段の排気通路１０に備えた尿素水供給装置１５より噴射される尿素水Ｕを排気ガスＧの熱により加水分解して生成されたアンモニア（ＮＨ3）を還元剤として、排気ガスＧに含まれる窒素酸化物（ＮＯｘ）を窒素（Ｎ2）に浄化する装置である。 The selective reduction catalyst device 13 reduces ammonia (NH 3 ) generated by hydrolyzing the urea water U injected from the urea water supply device 15 provided in the exhaust passage 10 at the preceding stage with the heat of the exhaust gas G. The agent is a device that purifies nitrogen oxides (NOx) contained in the exhaust gas G into nitrogen (N 2 ).

なお、排気ガスＧに含まれるＮＯｘの浄化に使用されないアンモニアは、選択還元型触媒装置１３の内部に吸蔵されるか、または、選択還元型触媒装置１３より下流側の排気通路１０に流出（スリップ）する。また、図２に示すように、選択還元型触媒装置１３のアンモニア吸蔵容量（アンモニアを吸蔵可能な上限量）Ａは、選択還元型触媒装置１３の温度が高くなるにつれて、少なくなる。 It should be noted that ammonia that is not used for purifying NOx contained in the exhaust gas G is stored inside the selective reduction catalyst device 13 or flows out (slip) to the exhaust passage 10 on the downstream side of the selective reduction catalyst device 13. ) Do. Further, as shown in FIG. 2, the ammonia storage capacity A (upper limit amount of ammonia that can be stored) A of the selective reduction catalyst device 13 decreases as the temperature of the selective reduction catalyst device 13 increases.

また、本発明の排気ガス浄化システム１を制御する制御装置４０が配設される。この制御装置４０は、エンジン２の運転状態等を表す各種センサの検出値を基に、尿素水供給装置１５からの尿素水Ｕの供給量等を制御する装置である。 Further, a control device 40 that controls the exhaust gas purification system 1 of the present invention is provided. The control device 40 is a device that controls the supply amount and the like of the urea water U from the urea water supply device 15 based on the detection values of various sensors that represent the operating state of the engine 2.

尿素水供給装置１５からの尿素水Ｕの供給量は、エンジン２の運転状態に応じて制御装置４０により制御されるが、この供給量の緻密な制御は困難である。したがって、例えば、エンジン２の運転状態が急激に変化して尿素水供給装置１５より尿素水Ｕを排気通路１０に過剰に供給した場合には、大量に発生したアンモニアが排気ガスＧに含まれるＮＯｘの浄化にも選択還元型触媒装置１３へのアンモニア吸蔵にも使用されないで、選択還元型触媒装置１３より下流側の排気通路１０にアンモニアが流出する、所謂アンモニアスリップが発生する虞がある。また、例えば、排気ガスＧの急激な高温化に伴い、選択還元型触媒装置１３が急激に昇温した場合には、選択還元型触媒装置１３のアンモニア吸蔵容量が急激に減少するので、その内部に吸蔵していたアンモニアの一部が下流側の排気通路１０に流出（スリップ）する虞がある。 The supply amount of the urea water U from the urea water supply device 15 is controlled by the control device 40 according to the operating state of the engine 2, but precise control of this supply amount is difficult. Therefore, for example, when the operating state of the engine 2 is drastically changed and the urea water supply device 15 excessively supplies the urea water U to the exhaust passage 10, a large amount of generated ammonia is contained in the exhaust gas G. There is a risk that ammonia is discharged to the exhaust passage 10 on the downstream side of the selective reduction catalyst device 13, that is, so-called ammonia slip, which is not used for purifying the exhaust gas and for storing ammonia in the selective reduction catalyst device 13. Further, for example, when the selective reduction catalyst device 13 rapidly rises in temperature as the exhaust gas G rapidly rises in temperature, the ammonia storage capacity of the selective reduction catalyst device 13 sharply decreases. There is a possibility that part of the ammonia stored in the exhaust gas may flow out (slip) to the exhaust passage 10 on the downstream side.

従来技術の内燃機関の排気ガス浄化システム１Ｘでは、図４に示すように、選択還元型触媒装置１３より下流側にアンモニアスリップ触媒装置（構造は酸化触媒装置１１と同様）１４を備えて、このアンモニアスリップ触媒装置１４により選択還元型触媒装置１３から流出したアンモニアを窒素に浄化していた。しかしながら、この浄化反応の副生成物としてＮＯｘを生成することがあり、排気ガス浄化システム全体でのＮＯｘ浄化性能が低下してしまう問題があった。 In an exhaust gas purification system 1X for an internal combustion engine according to the related art, as shown in FIG. 4, an ammonia slip catalyst device (having the same structure as the oxidation catalyst device 11) 14 is provided on the downstream side of the selective reduction catalyst device 13. The ammonia flowing out of the selective reduction catalyst device 13 was purified to nitrogen by the ammonia slip catalyst device 14. However, there is a problem that NOx may be produced as a by-product of this purification reaction, and the NOx purification performance of the entire exhaust gas purification system may deteriorate.

そこで、本発明の排気ガス浄化システム１では、図１に示すように、尿素水供給装置１５より上流側の排気通路１０に、排気ガス冷却装置２１を有する分岐通路２０を排気通路１０に平行して備えるとともに、分岐通路２０の分岐点に三方弁（流路切替装置）２２を備える。また、選択還元型触媒装置１３の温度を検出する温度検出センサ３０を選択還元型触媒装置１３の内部（図１ではこの位置）、または、選択還元型触媒装置１３の上流側または下流側の排気通路１０に備えるとともに、選択還元型触媒装置１３の下流側の排気通路１０にアンモニア濃度検出センサ３１を備える。 Therefore, in the exhaust gas purification system 1 of the present invention, as shown in FIG. 1, a branch passage 20 having an exhaust gas cooling device 21 is arranged in parallel with the exhaust passage 10 on the upstream side of the urea water supply device 15. And a three-way valve (flow path switching device) 22 at the branch point of the branch passage 20. Further, the temperature detection sensor 30 for detecting the temperature of the selective reduction catalyst device 13 is disposed inside the selective reduction catalyst device 13 (at this position in FIG. 1) or exhaust gas on the upstream side or the downstream side of the selective reduction catalyst device 13. In addition to being provided in the passage 10, an ammonia concentration detection sensor 31 is provided in the exhaust passage 10 on the downstream side of the selective reduction catalyst device 13.

なお、排気ガス冷却装置２１には、空気やエンジン冷却水やラジエータ用冷却水等の冷却媒体がその内部の冷却媒体用通路（図示しない）に流通しており、この冷却媒体用通路に隣接する排気ガス用通路（図示しない）を通過する排気ガスＧｂを冷却媒体により冷却している。 In the exhaust gas cooling device 21, a cooling medium such as air, engine cooling water, radiator cooling water, etc. circulates in a cooling medium passage (not shown) therein, and is adjacent to the cooling medium passage. The exhaust gas Gb passing through the exhaust gas passage (not shown) is cooled by a cooling medium.

また、温度検出センサ３０の設置位置について、図１に示すように選択還元型触媒装置１３の内部に温度検出センサ３０を設けて、選択還元型触媒装置１３の温度を直接検出するのが好ましいが、選択還元型触媒装置１３の上流側または下流側の排気通路１０に温度検出センサ３０を備えて、この温度検出センサ３０の検出値を選択還元型触媒装置１３の温度として代用してもよい。 Regarding the installation position of the temperature detection sensor 30, it is preferable that the temperature detection sensor 30 is provided inside the selective reduction catalyst device 13 as shown in FIG. 1 to directly detect the temperature of the selective reduction catalyst device 13. The temperature detection sensor 30 may be provided in the exhaust passage 10 on the upstream side or the downstream side of the selective reduction catalyst device 13, and the detection value of the temperature detection sensor 30 may be used as the temperature of the selective reduction catalyst device 13.

そして、制御装置４０が、温度検出センサ３０の検出値Ｔが予め設定された冷却開始温度閾値Ｔ１以上となったときに、または、アンモニア濃度検出センサ３１の検出値Ｄが予め設定された冷却開始濃度閾値Ｄ１以上となったときに、三方弁２２を制御して、排気ガスＧの流れを排気通路１０から分岐通路２０に切り替える制御を行うように構成する。この冷却開始温度閾値Ｔ１は、これ以上排気ガスＧの温度が高くなると、選択還元型触媒装置１３へのアンモニア吸着容量Ａが低下して、アンモニア吸着元性能が低下してしまう値であり、実験等により予め設定される値である。また、冷却開始濃度閾値Ｄ１は、この濃度以上にアンモニアスリップ量が増加してしまうのを防止したい値であり、実験等により予め設定される値である。 Then, the control device 40 starts cooling when the detection value T of the temperature detection sensor 30 becomes equal to or higher than the preset cooling start temperature threshold T1 or when the detection value D of the ammonia concentration detection sensor 31 is preset. When the concentration becomes equal to or higher than the threshold value D1, the three-way valve 22 is controlled so that the flow of the exhaust gas G is switched from the exhaust passage 10 to the branch passage 20. This cooling start temperature threshold value T1 is a value at which the ammonia adsorption capacity A to the selective reduction catalyst device 13 is reduced and the ammonia adsorption source performance is reduced when the temperature of the exhaust gas G is further increased. It is a value preset by the above. Further, the cooling start concentration threshold value D1 is a value that is desired to prevent the ammonia slip amount from increasing above this concentration, and is a value set in advance by experiments or the like.

すなわち、選択還元型触媒装置１３からのアンモニアスリップを検出した場合、または、選択還元型触媒装置１３の温度Ｔが高温であり、アンモニア吸蔵容量Ａが小さい場合に、選択還元型触媒装置１３に流入する前の排気ガスＧの全量を排気ガス冷却装置２１により冷却して、低温化した排気ガスＧを選択還元型触媒装置１３に流入させることで、アンモニア吸蔵容量Ａを速やかに大きくして、選択還元型触媒装置１３からのアンモニアスリップを防止または予防する。 That is, when ammonia slip from the selective reduction catalyst device 13 is detected, or when the temperature T of the selective reduction catalyst device 13 is high and the ammonia storage capacity A is small, the ammonia flows into the selective reduction catalyst device 13. The exhaust gas cooling device 21 cools the entire amount of the exhaust gas G before the operation, and the exhaust gas G whose temperature has been lowered is caused to flow into the selective reduction catalyst device 13, whereby the ammonia storage capacity A is rapidly increased and selected. The ammonia slip from the reduction catalyst device 13 is prevented or prevented.

したがって、この構成によれば、排気通路１０にアンモニアスリップ触媒装置１４を備える必要のない量まで選択還元型触媒装置１３からのアンモニアスリップを抑制することができ、アンモニアスリップ触媒装置１４を不要にできるとともに、アンモニアスリップ触媒装置１４でのアンモニアの浄化反応によるＮＯｘの生成量を減少させることができるので、排気ガス浄化システム１全体でのＮＯｘ浄化性能を維持することができる。 Therefore, according to this configuration, ammonia slip from the selective reduction catalyst device 13 can be suppressed to an amount that does not require the ammonia slip catalyst device 14 in the exhaust passage 10, and the ammonia slip catalyst device 14 can be omitted. At the same time, since the amount of NOx produced by the ammonia purification reaction in the ammonia slip catalyst device 14 can be reduced, the NOx purification performance of the entire exhaust gas purification system 1 can be maintained.

また、上記の内燃機関の排気ガス浄化システム１において、制御装置４０が、温度検出センサ３０の検出値Ｔが予め設定された冷却終了温度閾値Ｔ２以下となったときに、流路切替装置２２を制御して、排気ガスＧの流れを分岐通路２０から排気通路１０に切り替える制御を行うように構成する。この冷却終了温度閾値Ｔ２は、冷却開始温度閾値Ｔ１より低い値であり、これ以上排気ガスＧの温度を低下させると、選択還元型触媒装置１３に担持されている触媒の温度が低くなり過ぎて、ＮＯｘの還元性能が低下してしまう値であり、実験等により予め設定される値である。 In the exhaust gas purification system 1 for the internal combustion engine, the control device 40 causes the flow path switching device 22 to operate when the detected value T of the temperature detection sensor 30 becomes equal to or lower than the preset cooling end temperature threshold T2. The flow of the exhaust gas G is controlled to switch from the branch passage 20 to the exhaust passage 10. This cooling end temperature threshold value T2 is a value lower than the cooling start temperature threshold value T1, and when the temperature of the exhaust gas G is further reduced, the temperature of the catalyst carried by the selective reduction catalytic converter 13 becomes too low. , A value at which the NOx reduction performance deteriorates, and is a value set in advance by experiments or the like.

この構成によれば、選択還元型触媒装置１３に担持される触媒の温度が活性温度範囲から外れた温度まで低下することを防止できるので、選択還元型触媒装置１３からのアンモニアスリップを防止しつつ、そのＮＯｘ浄化性能を維持することができる。 According to this configuration, it is possible to prevent the temperature of the catalyst carried by the selective reduction catalyst device 13 from dropping to a temperature outside the activation temperature range, so that ammonia slip from the selective reduction catalyst device 13 is prevented. The NOx purification performance can be maintained.

なお、図２に示すように、上記の冷却開始温度閾値Ｔ１及び冷却終了温度閾値Ｔ２は、選択還元型触媒装置１３のＮＯｘ浄化率Ｐが予め設定されたＮＯｘ浄化率Ｐ１以上となる温度範囲である要求ＮＯｘ浄化率範囲（図２では、Ｔ２≦Ｔ≦Ｔ３）内で設定するのがより好ましい。このＮＯｘ浄化率Ｐ１は、ＮＯｘの浄化の目標に応じて、実験等により予め設定される値である。 As shown in FIG. 2, the cooling start temperature threshold value T1 and the cooling end temperature threshold value T2 are in a temperature range in which the NOx purification rate P of the selective reduction catalytic converter 13 is equal to or higher than the preset NOx purification rate P1. It is more preferable to set within a certain required NOx purification rate range (T2≦T≦T3 in FIG. 2). The NOx purification rate P1 is a value preset by experiments or the like according to the target of NOx purification.

なお、図１では流路切替装置として三方弁２２を備えたが、流路切替機能だけでなく流量調整機能も備えた流量調整弁（流量調整装置）２２を代わりに備えてもよい。この場合は、三方弁２２のように排気通路１０または分岐通路２０のいずれか一方に排気ガスＧを流通させるのではなく、排気通路１０または分岐通路２０のいずれか一方または両方に排気ガスＧを流通させることができる。 Although the three-way valve 22 is provided as the flow path switching device in FIG. 1, a flow rate adjusting valve (flow rate adjusting device) 22 having not only the flow path switching function but also the flow rate adjusting function may be provided instead. In this case, the exhaust gas G is not passed through either the exhaust passage 10 or the branch passage 20 like the three-way valve 22, but the exhaust gas G is passed through either the exhaust passage 10 or the branch passage 20 or both. It can be distributed.

三方弁２２のように、排気通路１０と分岐通路２０の間の排気ガスＧの流れを即時に切り替える構成であると、流路切替装置の制御が簡単となり、選択還元型触媒装置１３に流入する排気ガスＧの温度を迅速に低下させて、選択還元型触媒装置１３の温度低下によりアンモニア吸蔵容量Ａを即時に大きくすることができるので、選択還元型触媒装置１３からのアンモニアスリップをより確実かつ迅速に防止することができる。 When the flow of the exhaust gas G between the exhaust passage 10 and the branch passage 20 is instantly switched like the three-way valve 22, the control of the flow passage switching device becomes simple and flows into the selective reduction catalyst device 13. Since the temperature of the exhaust gas G can be rapidly reduced and the ammonia storage capacity A can be immediately increased by the temperature reduction of the selective reduction catalyst device 13, the ammonia slip from the selective reduction catalyst device 13 can be more reliably and reliably performed. It can be prevented quickly.

これに対して、制御装置４０が、排気ガスＧの流れを排気通路１０と分岐通路２０の間で切り替えるときに、三方弁２２のように即時に切り替えるのではなく、徐々にまたは段階的に切り替えることができるので、選択還元型触媒装置１３の温度の急変動を防止して、ＮＯｘ浄化率の急変動を防止することができる。また、排気通路１０と分岐通路２０に流す排気ガスＧの分配量を調整制御でき、きめ細かく排気ガスＧの温度を調整することができる。 On the other hand, when the control device 40 switches the flow of the exhaust gas G between the exhaust passage 10 and the branch passage 20, the control device 40 does not switch it immediately like the three-way valve 22, but switches gradually or stepwise. Therefore, it is possible to prevent a sudden change in the temperature of the selective reduction catalyst device 13 and prevent a sudden change in the NOx purification rate. Further, the distribution amount of the exhaust gas G flowing in the exhaust passage 10 and the branch passage 20 can be adjusted and controlled, and the temperature of the exhaust gas G can be finely adjusted.

また、制御装置４０が、この切替時に、アンモニア濃度検出センサ３１の検出値の変動量ΔＤに応じて分岐通路２０を通過する排気ガスＧの流量の変動量ΔＶを設定して、流量調整弁２２を制御するように構成すると、選択還元型触媒装置１３からのアンモニアスリップ量が急激に増加したときでも、排気ガス冷却装置２１により冷却される排気ガスＧの量を即時に増加させて、排気ガスＧの冷却を促進することで、選択還元型触媒装置１３のアンモニア吸蔵容量Ａを大きくすることができるので、選択還元型触媒装置１３からのアンモニアスリップをより迅速に防止することができる。 Further, at the time of this switching, the control device 40 sets the variation amount ΔV of the flow rate of the exhaust gas G passing through the branch passage 20 in accordance with the variation amount ΔD of the detection value of the ammonia concentration detection sensor 31, and the flow rate adjusting valve 22. The exhaust gas cooling device 21 immediately increases the amount of the exhaust gas G cooled by the exhaust gas cooling device 21 even when the ammonia slip amount from the selective reduction catalyst device 13 suddenly increases. By promoting the cooling of G, the ammonia storage capacity A of the selective reduction catalyst device 13 can be increased, so that ammonia slip from the selective reduction catalyst device 13 can be prevented more quickly.

なお、このとき、排気ガス冷却装置２１を通過する冷却媒体の量を通常の冷却媒体の量より多くすると、排気ガスＧの冷却をより促進することができるので好ましい。 At this time, it is preferable that the amount of the cooling medium passing through the exhaust gas cooling device 21 is larger than the amount of the normal cooling medium, because the cooling of the exhaust gas G can be further promoted.

次に、上記の内燃機関の排気ガス浄化システム１を用いた、本発明の内燃機関の排気ガス浄化方法の制御フローについて、図３を参照しながら説明する。図３の制御フローは、エンジン２の運転中に予め設定した制御時間毎に、上級の制御フローより呼ばれてスタートする制御フローである。 Next, a control flow of the exhaust gas purifying method for an internal combustion engine of the present invention using the above exhaust gas purifying system 1 for an internal combustion engine will be described with reference to FIG. The control flow of FIG. 3 is a control flow that is called by a higher-level control flow and starts at every control time set in advance while the engine 2 is operating.

図３の制御フローがスタートすると、ステップＳ１０にて、選択還元型触媒装置１３に流入する排気ガスＧを排気ガス冷却装置２１により冷却して、選択還元型触媒装置１３のアンモニア吸蔵容量Ａを大きくする必要があるか否かを判定する。この判定は、選択還元型触媒装置１３の温度（温度検出センサ３０の検出値）Ｔが冷却開始温度閾値Ｔ１以上となったか否か、または、選択還元型触媒装置１３より下流側の排気通路１０を通過する排気ガスＧｃのアンモニア濃度（アンモニア濃度検出センサ３１の検出値）Ｄが冷却開始濃度閾値Ｄ１以上となったか否かにより行う。 When the control flow of FIG. 3 starts, in step S10, the exhaust gas G flowing into the selective reduction catalyst device 13 is cooled by the exhaust gas cooling device 21 to increase the ammonia storage capacity A of the selective reduction catalyst device 13. It is determined whether it is necessary to do. This determination is made based on whether or not the temperature T of the selective reduction catalyst device 13 (detection value of the temperature detection sensor 30) becomes equal to or higher than the cooling start temperature threshold T1, or the exhaust passage 10 on the downstream side of the selective reduction catalyst device 13. This is performed depending on whether or not the ammonia concentration (detection value of the ammonia concentration detection sensor 31) D of the exhaust gas Gc passing through is equal to or higher than the cooling start concentration threshold D1.

ステップＳ１０にて、選択還元型触媒装置１３の温度Ｔが冷却開始温度閾値Ｔ１未満であり、かつ、排気ガスＧｃのアンモニア濃度Ｄが冷却開始濃度閾値Ｄ１未満である場合（ＮＯ）には、排気ガスＧの冷却が不要であるとして、リターンに進んで、本制御フローを終了する。 In step S10, if the temperature T of the selective reduction catalytic converter 13 is lower than the cooling start temperature threshold T1 and the ammonia concentration D of the exhaust gas Gc is lower than the cooling start concentration threshold D1 (NO), the exhaust gas is exhausted. Assuming that the cooling of the gas G is unnecessary, the process proceeds to the return and the control flow ends.

一方、ステップＳ１０にて、選択還元型触媒装置１３の温度Ｔが冷却開始温度Ｔ１以上であるか、または、排気ガスＧｃのアンモニア濃度Ｄが冷却開始濃度閾値Ｄ１以上である場合（ＹＥＳ）には、排気ガスＧｃの冷却が必要であるとして、ステップＳ２０に進み、ステップＳ２０にて、流路切替装置２２を制御して、排気ガスＧの流れを排気通路１０から分岐通路２０に切り替える制御を行う。流路切替装置として三方弁２２を用いたときは、排気ガスＧが全量排気通路１０から分岐通路２０に一気に切り替わる。一方、流路切替装置として流量調整弁２２を用いたときは、排気通路１０へ流れる排気ガスＧａの流量を減少させながら（分岐通路２２へ流れる排気ガスＧｂの流量を増加させながら）、排気ガスＧの流れを排気通路１０から分岐通路２０に徐々に切り替える。あるいは、分岐通路２０へ流れる排気ガスＧｂの流量を増加させた状態とする。ステップＳ２０の制御を実施後、ステップＳ３０に進む。 On the other hand, in step S10, if the temperature T of the selective reduction catalyst device 13 is the cooling start temperature T1 or higher, or if the ammonia concentration D of the exhaust gas Gc is the cooling start concentration threshold D1 or higher (YES). Assuming that the exhaust gas Gc needs to be cooled, the process proceeds to step S20, and in step S20, the flow path switching device 22 is controlled to switch the flow of the exhaust gas G from the exhaust passage 10 to the branch passage 20. .. When the three-way valve 22 is used as the flow passage switching device, the exhaust gas G is switched from the exhaust passage 10 to the branch passage 20 all at once. On the other hand, when the flow rate control valve 22 is used as the flow path switching device, the flow rate of the exhaust gas Ga flowing into the exhaust passage 10 is reduced (while the flow rate of the exhaust gas Gb flowing into the branch passage 22 is increased), The flow of G is gradually switched from the exhaust passage 10 to the branch passage 20. Alternatively, the flow rate of the exhaust gas Gb flowing into the branch passage 20 is increased. After performing the control in step S20, the process proceeds to step S30.

なお、この切替時に、排気ガスＧｃのアンモニア濃度の変動量ΔＤに応じて分岐通路２０を通過する排気ガスＧｂの流量の変動量ΔＶを設定して、流量調整弁２２を制御すると、選択還元型触媒装置１３からのアンモニアスリップ量が急激に増加したときでも、排気ガス冷却装置２１により冷却される排気ガスＧｂの量を即時に増加させて、排気ガスＧｂの冷却を促進することで、選択還元型触媒装置１３の温度を低下させてアンモニア吸蔵容量Ａを大きくすることができるので、選択還元型触媒装置１３からのアンモニアスリップをより迅速に防止することができる。 At the time of this switching, if the flow rate adjustment valve 22 is controlled by setting the flow rate variation amount ΔV of the exhaust gas Gb passing through the branch passage 20 in accordance with the variation amount ΔD of the ammonia concentration of the exhaust gas Gc, the selective reduction type Even when the amount of ammonia slip from the catalyst device 13 suddenly increases, the amount of the exhaust gas Gb cooled by the exhaust gas cooling device 21 is immediately increased to accelerate the cooling of the exhaust gas Gb, thereby performing the selective reduction. Since the temperature of the catalytic converter 13 can be lowered and the ammonia storage capacity A can be increased, ammonia slip from the selective reduction catalytic converter 13 can be prevented more quickly.

ステップＳ３０にて、選択還元型触媒装置１３に流入する排気ガスＧの冷却が不要となったか否かを判定する。この判定は、選択還元型触媒装置１３の温度（温度検出センサ３０の検出値）Ｔが冷却開始温度閾値Ｔ１より低い値である冷却終了温度閾値Ｔ２以下となったか否かにより行う。 In step S30, it is determined whether cooling of the exhaust gas G flowing into the selective catalytic reduction device 13 has become unnecessary. This determination is made based on whether or not the temperature T of the selective reduction catalyst device 13 (detection value of the temperature detection sensor 30) becomes equal to or lower than the cooling end temperature threshold T2 which is a value lower than the cooling start temperature threshold T1.

ステップＳ３０にて、選択還元型触媒装置１３の温度が冷却終了温度閾値Ｔ２より高い場合（ＮＯ）には、排気ガスＧの冷却が依然必要であると判定して、実験等により予め設定した制御時間を経過後、再度ステップＳ３０の判定を行う。 In step S30, when the temperature of the selective reduction catalyst device 13 is higher than the cooling end temperature threshold value T2 (NO), it is determined that the exhaust gas G still needs to be cooled, and the preset control is performed through experiments or the like. After the lapse of time, the determination in step S30 is performed again.

一方、ステップＳ３０にて、選択還元型触媒装置１３の温度が冷却終了温度閾値Ｔ２以下となった場合（ＹＥＳ）には、ステップＳ４０に進み、ステップＳ４０にて、流路切替装置２２を制御して、排気ガスＧの流れを分岐通路２０から排気通路１０に切り替える制御を行う。流路切替装置として三方弁２２を用いたときは、排気ガスＧが全量分岐通路２０から排気通路１０に一気に切り替わる。一方、流路切替装置として流量調整弁２２を用いたときは、分岐通路２０へ流れる排気ガスＧｂの流量を減少させながら（排気通路１０へ流れる排気ガスＧａの流量を増加させながら）、排気ガスＧの流れを分岐通路２０から排気通路１０に徐々に切り替える。あるいは、分岐通路２０へ流れる排気ガスＧｂの流量を減少させた状態とする。ステップＳ４０の制御を実施後、リターンに進んで、本制御フローを終了する。 On the other hand, if the temperature of the selective reduction catalyst device 13 becomes equal to or lower than the cooling end temperature threshold T2 in step S30 (YES), the process proceeds to step S40, and the flow path switching device 22 is controlled in step S40. Then, control is performed to switch the flow of the exhaust gas G from the branch passage 20 to the exhaust passage 10. When the three-way valve 22 is used as the flow path switching device, the exhaust gas G is switched from the total amount branch passage 20 to the exhaust passage 10 at once. On the other hand, when the flow rate adjusting valve 22 is used as the flow path switching device, the flow rate of the exhaust gas Gb flowing into the branch passage 20 is decreased (while the flow rate of the exhaust gas Ga flowing into the exhaust passage 10 is increased), and the exhaust gas is reduced. The flow of G is gradually switched from the branch passage 20 to the exhaust passage 10. Alternatively, the flow rate of the exhaust gas Gb flowing into the branch passage 20 is reduced. After performing the control of step S40, the process proceeds to return and the present control flow ends.

以上より、本発明の内燃機関の排気ガス浄化システム１を基にした、本発明の内燃機関の排気ガス浄化方法は、エンジン２の排気通路１０に上流側より順に尿素水供給装置１５、選択還元型触媒装置１３を備えるとともに、尿素水供給装置１５より上流側の排気通路１３に、排気ガス冷却装置２１を有する分岐通路２０を排気通路１０に並行して備えて、分岐通路２０の分岐点に流路切替装置２２を備えて構成される内燃機関の排気ガス浄化方法において、選択還元型触媒装置１３の温度Ｔが実験等により予め設定された冷却開始温度閾値Ｔ１以上となったときに、または、選択還元型触媒装置１３より下流側の排気通路１０を通過する排気ガスＧｃのアンモニア濃度Ｄが実験等により予め設定された冷却開始濃度閾値Ｄ１以上となったときに、流路切替装置２２を制御して、排気ガスＧの流れを排気通路１０から分岐通路２０に切り替えることを特徴とする方法となる。 As described above, the exhaust gas purification method for an internal combustion engine according to the present invention based on the exhaust gas purification system 1 for an internal combustion engine according to the present invention is applied to the exhaust passage 10 of the engine 2 in order from the upstream side to the urea water supply device 15 and the selective reduction. Type catalyst device 13 is provided, and a branch passage 20 having an exhaust gas cooling device 21 is provided in the exhaust passage 13 upstream of the urea water supply device 15 in parallel with the exhaust passage 10 at a branch point of the branch passage 20. In an exhaust gas purification method for an internal combustion engine configured to include a flow path switching device 22, when the temperature T of the selective reduction catalyst device 13 becomes equal to or higher than a cooling start temperature threshold T1 preset by experiments or the like, or When the ammonia concentration D of the exhaust gas Gc passing through the exhaust passage 10 on the downstream side of the selective reduction catalyst device 13 becomes equal to or higher than the cooling start concentration threshold D1 preset by experiments or the like, the flow path switching device 22 is turned on. The method is characterized by controlling and switching the flow of the exhaust gas G from the exhaust passage 10 to the branch passage 20.

本発明の内燃機関の排気ガス浄化システム１及び内燃機関の排気ガス浄化方法によれば、選択還元型触媒装置１３からのアンモニアスリップを抑制しつつ、排気ガス浄化システム１全体でのＮＯｘ浄化性能を維持することができる。 According to the exhaust gas purification system 1 for an internal combustion engine and the exhaust gas purification method for an internal combustion engine of the present invention, NOx purification performance of the entire exhaust gas purification system 1 can be improved while suppressing ammonia slip from the selective reduction catalyst device 13. Can be maintained.

１、１Ｘ 内燃機関の排気ガス浄化システム
２ エンジン
１０ 排気通路
１３ 選択還元型触媒装置（ＳＣＲ）
１５ 尿素水供給装置
２０ 分岐通路
２１ 排気ガス冷却装置
２２ 三方弁（流路切替装置）、流量調整弁（流量調整装置）
３０ 温度検出センサ（温度検出装置）
３１ アンモニア濃度検出センサ（アンモニア濃度検出装置）
４０ 制御装置
Ｇ 排気ガス
Ｇａ 排気通路を通過する排気ガス
Ｇｂ 分岐通路を通過する排気ガス
Ｔ 選択還元型触媒装置の温度（温度検出センサの検出値）
Ｔ１ 冷却開始温度閾値
Ｔ２ 冷却終了温度閾値
Ｄ アンモニア濃度検出センサの検出値
Ｄ１ 冷却開始濃度閾値
ΔＤ アンモニア濃度検出センサの検出値の変動量
ΔＶ 分岐通路を通過する排気ガスの流量の変動量 1, 1X Exhaust Gas Purification System for Internal Combustion Engine 2 Engine 10 Exhaust Passage 13 Selective Reduction Catalyst (SCR)
15 Urea water supply device 20 Branch passage 21 Exhaust gas cooling device 22 Three-way valve (flow path switching device), flow rate adjusting valve (flow rate adjusting device)
30 Temperature detection sensor (temperature detection device)
31 Ammonia concentration detection sensor (ammonia concentration detection device)
40 Control Device G Exhaust Gas Ga Exhaust Gas Gb Passing Through Exhaust Passage Exhaust Gas T Passing Through Branch Passage T Temperature of Selective Reduction Type Catalyst Device (Detection Value of Temperature Detection Sensor)
T1 cooling start temperature threshold value T2 cooling end temperature threshold value D detection value of ammonia concentration detection sensor D1 cooling start concentration threshold value ΔD fluctuation amount of detection value of ammonia concentration detection sensor ΔV fluctuation amount of exhaust gas flow rate passing through branch passage

Claims (4)

内燃機関の排気通路に上流側より順に尿素水供給装置、選択還元型触媒装置を備えて構成される内燃機関の排気ガス浄化システムにおいて、
前記尿素水供給装置より上流側の前記排気通路に、排気ガス冷却装置を有する分岐通路を前記排気通路に並行して備えて、前記分岐通路の分岐点に流路切替装置を備えるとともに、
前記選択還元型触媒装置の内部、または、前記選択還元型触媒装置の上流側または下流側の前記排気通路に温度検出装置を備え、前記選択還元型触媒装置の下流側の前記排気通路にアンモニア濃度検出装置を備えて、
前記排気ガス浄化システムを制御する制御装置が、
前記温度検出装置の検出値が予め設定された冷却開始温度閾値以上となったときに、または、前記アンモニア濃度検出装置の検出値が予め設定された冷却開始濃度閾値以上となったときに、前記流路切替装置を制御して、排気ガスの流れを前記排気通路から前記分岐通路に切り替える制御を行うように構成される内燃機関の排気ガス浄化システム。 In an exhaust gas purifying system for an internal combustion engine, which comprises an urea water supply device and a selective reduction type catalyst device in order from the upstream side in an exhaust passage of the internal combustion engine,
In the exhaust passage upstream of the urea water supply device, a branch passage having an exhaust gas cooling device is provided in parallel with the exhaust passage, and a flow path switching device is provided at a branch point of the branch passage,
A temperature detecting device is provided inside the selective reduction catalyst device or in the exhaust passage upstream or downstream of the selective reduction catalyst device, and an ammonia concentration is provided in the exhaust passage downstream of the selective reduction catalyst device. Equipped with a detector,
A control device for controlling the exhaust gas purification system,
When the detection value of the temperature detection device is equal to or higher than a preset cooling start temperature threshold value, or when the detection value of the ammonia concentration detection device is equal to or higher than a preset cooling start concentration threshold value, An exhaust gas purification system for an internal combustion engine configured to control a flow passage switching device to perform control to switch a flow of exhaust gas from the exhaust passage to the branch passage. 前記制御装置が、
前記温度検出装置の検出値が前記冷却開始温度閾値より低い値として予め設定された冷却終了温度閾値以下となったときに、前記流路切替装置を制御して、排気ガスの流れを前記分岐通路から前記排気通路に切り替える制御を行うように構成される請求項１に記載の内燃機関の排気ガス浄化システム。 The control device is
When the detected value of the temperature detection device becomes equal to or lower than the cooling end temperature threshold value preset as a value lower than the cooling start temperature threshold value, the flow path switching device is controlled to change the flow of exhaust gas to the branch passage. The exhaust gas purification system for an internal combustion engine according to claim 1, wherein the exhaust gas purification system is configured to perform control to switch from the exhaust passage to the exhaust passage. 前記流路切替装置を、前記排気通路または前記分岐通路の両方に排気ガスを流通できる流量調整装置として構成するとともに、
前記制御装置が、
排気ガスの流れを前記排気通路と前記分岐通路の間で切り替えるときに、
前記アンモニア濃度検出装置の検出値の変動量に応じて前記分岐通路を通過する排気ガスの流量の変動量を設定して、前記流量調整装置を制御するように構成される請求項１または２に記載の内燃機関の排気ガス浄化システム。 While configuring the flow path switching device as a flow rate adjusting device capable of flowing exhaust gas in both the exhaust passage or the branch passage,
The control device is
When switching the flow of exhaust gas between the exhaust passage and the branch passage,
The amount of fluctuation of the flow rate of the exhaust gas passing through the branch passage is set according to the amount of fluctuation of the detection value of the ammonia concentration detecting device, and the flow rate adjusting device is controlled. An exhaust gas purification system for an internal combustion engine as described. 内燃機関の排気通路に上流側より順に尿素水供給装置、選択還元型触媒装置を備えるとともに、前記尿素水供給装置より上流側の前記排気通路に、排気ガス冷却装置を有する分岐通路を前記排気通路に並行して備えて、前記分岐通路の分岐点に流路切替装置を備えて構成される内燃機関の排気ガス浄化方法において、
前記選択還元型触媒装置の温度が予め設定された冷却開始温度閾値以上となったときに、または、前記選択還元型触媒装置より下流側の前記排気通路を通過する排気ガスのアンモニア濃度が予め設定された冷却開始濃度閾値以上となったときに、前記流路切替装置を制御して、排気ガスの流れを前記排気通路から前記分岐通路に切り替えることを特徴とする内燃機関の排気ガス浄化方法。 The exhaust passage of the internal combustion engine is provided with a urea water supply device and a selective reduction type catalyst device in order from the upstream side, and a branch passage having an exhaust gas cooling device is provided in the exhaust passage upstream of the urea water supply device. In parallel with, in the exhaust gas purification method of an internal combustion engine configured to include a flow path switching device at the branch point of the branch passage,
When the temperature of the selective reduction catalyst device becomes equal to or higher than a preset cooling start temperature threshold value, or the ammonia concentration of the exhaust gas passing through the exhaust passage downstream of the selective reduction catalyst device is preset. An exhaust gas purifying method for an internal combustion engine, comprising controlling the flow path switching device to switch the flow of exhaust gas from the exhaust passage to the branch passage when the cooling start concentration threshold is exceeded.
JP2016111805A 2016-06-03 2016-06-03 Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine Active JP6705294B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2016111805A JP6705294B2 (en) 2016-06-03 2016-06-03 Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2016111805A JP6705294B2 (en) 2016-06-03 2016-06-03 Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine

Publications (2)

Publication Number Publication Date
JP2017218913A JP2017218913A (en) 2017-12-14
JP6705294B2 true JP6705294B2 (en) 2020-06-03

Family

ID=60657324

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2016111805A Active JP6705294B2 (en) 2016-06-03 2016-06-03 Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine

Country Status (1)

Country Link
JP (1) JP6705294B2 (en)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3267188B2 (en) * 1997-05-12 2002-03-18 トヨタ自動車株式会社 Catalyst deterioration determination device for internal combustion engine
US6871489B2 (en) * 2003-04-16 2005-03-29 Arvin Technologies, Inc. Thermal management of exhaust systems
JP4224383B2 (en) * 2003-06-12 2009-02-12 日野自動車株式会社 Exhaust purification equipment
JP2010261423A (en) * 2009-05-11 2010-11-18 Toyota Motor Corp Exhaust emission control device of internal combustion engine
JP2013092106A (en) * 2011-10-26 2013-05-16 Nissan Motor Co Ltd Exhaust gas cleaning device for internal combustion engine
JP5861920B2 (en) * 2011-12-15 2016-02-16 三菱自動車工業株式会社 Exhaust gas purification device for internal combustion engine
JP2015094324A (en) * 2013-11-13 2015-05-18 トヨタ自動車株式会社 Engine control device

Also Published As

Publication number Publication date
JP2017218913A (en) 2017-12-14

Similar Documents

Publication Publication Date Title
JP3829699B2 (en) Exhaust gas purification system and its regeneration control method
JP4290037B2 (en) Engine exhaust purification system
JP2004316658A5 (en)
JP2007162578A (en) Control method for exhaust emission control system, and exhaust gas emission control system
JP2006207512A (en) Exhaust emission control device and exhaust emission control method for internal combustion engine
JP6733352B2 (en) Oxidation catalyst and exhaust gas purification system
JP6586377B2 (en) Exhaust purification device
JP2007154717A (en) Exhaust emission control device and exhaust emission control method for internal combustion engine
JP2008115775A (en) Exhaust emission control system for internal combustion engine
WO2007010985A1 (en) Exhaust gas purifier
US20100005788A1 (en) Method For Regenerating A Diesel Particulate Filter
JP2008038634A (en) Exhaust emission control device for internal combustion engine
JP4561467B2 (en) Exhaust gas purification method and exhaust gas purification system
JP2004162600A (en) Exhaust emission control device for internal combustion engine
JP2007198315A (en) Exhaust emission control device for internal combustion engine and exhaust emission control method
JP2005299474A (en) Exhaust gas purification system
JP6705294B2 (en) Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine
JP6753151B2 (en) Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine
JP2010156277A (en) Exhaust emission purifying method and exhaust emission purifying system
JP2020045884A (en) Exhaust gas treatment system and vehicle
JP6743498B2 (en) Exhaust gas purification system for internal combustion engine and exhaust gas purification method for internal combustion engine
CN110778384B (en) Control method and control device of post-processing system and post-processing system
JP2010043597A (en) Exhaust emission control device for internal combustion engine
JP2007263055A (en) Exhaust emission control device
JP2003148141A (en) Exhaust emission control device

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20190529

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20200317

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20200414

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20200427

R150 Certificate of patent or registration of utility model

Ref document number: 6705294

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150