JP2018204495A - Exhaust emission control system and control device - Google Patents

Exhaust emission control system and control device Download PDF

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JP2018204495A
JP2018204495A JP2017109234A JP2017109234A JP2018204495A JP 2018204495 A JP2018204495 A JP 2018204495A JP 2017109234 A JP2017109234 A JP 2017109234A JP 2017109234 A JP2017109234 A JP 2017109234A JP 2018204495 A JP2018204495 A JP 2018204495A
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exhaust gas
exhaust
passage
scr
temperature
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直人 村澤
Naoto Murasawa
直人 村澤
正 内山
Tadashi Uchiyama
正 内山
藤井 謙治
Kenji Fujii
謙治 藤井
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Isuzu Motors Ltd
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

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  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

To provide an exhaust emission control system capable of improving NOelimination efficiency of an SCR.SOLUTION: An exhaust emission control system in one embodiment includes: an exhaust passage that is a passage of exhaust gas; an NOocclusion catalyst for occluding NOin exhaust gas guided in the exhaust passage; an SCR provided downstream of the NOocclusion catalyst in the exhaust passage and eliminating NOin the exhaust gas; a bypass passage that is in fluid communication with the exhaust passage and bypasses the NOocclusion catalyst; and a passage change-over section that guides exhaust gas to the NOocclusion catalyst while a temperature of the SCR is a predetermined temperature or lower and that guides the exhaust gas to the bypass passage without guiding the exhaust gas to the NOocclusion catalyst when the temperature of the SCR exceeds the predetermined temperature.SELECTED DRAWING: Figure 2

Description

本開示は、内燃機関からの排ガス中のNOを浄化する排気浄化システムと、それに関連する制御装置と、に関する。 The present disclosure relates to an exhaust gas purification system that purifies NO x in exhaust gas from an internal combustion engine, and a control device related thereto.

従来、この種の排気浄化システムとしては、排気通路内にSCR(Selective Catalytic Reduction)を配置し、SCR上流の排気通路内にNO吸蔵触媒を配置したものが知られている。 Conventionally, as this type of exhaust purification system, an SCR (Selective Catalytic Reduction) is disposed in the exhaust passage, and an NO x storage catalyst is disposed in the exhaust passage upstream of the SCR.

特開2009−41442号公報JP 2009-41442 A

SCRにおけるNO浄化率を向上させるには、排ガス中にNOおよびNOが適度に含まれている必要がある。 To improve the NO x purification rate in the SCR, it is necessary to NO and NO 2 are included in the appropriate in the exhaust gas.

しかし、NO吸蔵触媒は、相対的に低温時から中温時に、排ガス中のNOを吸蔵出来るものの、NO吸蔵触媒の出口ではほぼNOのみとなるため、従来の排気浄化システムでは、SCRによるNO浄化率を向上させにくいという問題点があった。 However, the NO x storage catalyst from the time of the relatively low temperature at moderate temperatures, although it absorbs NO x in the exhaust gas, to become substantially only NO at the outlet of the NO x storage catalyst, in the conventional exhaust gas purification system, according to the SCR There was a problem that it was difficult to improve the NO x purification rate.

本開示は、SCRのNO浄化率を向上させることが可能な排気浄化システムおよび制御装置を提供することを目的とする。 An object of the present disclosure is to provide an exhaust purification system and a control device capable of improving the SCR NO x purification rate.

本開示の第1形態は、排ガスの通路である排気通路と、前記排気通路を案内されてきた排ガス中のNOを吸蔵するNO吸蔵触媒と、前記排気通路において前記NO吸蔵触媒の下流に設けられ、排ガス中のNOを浄化するSCRと、前記排気通路と流体連通し、前記NO吸蔵触媒をバイパスするバイパス通路と、前記SCRの温度が所定温度以下の間、前記NO吸蔵触媒に排ガスを導き、前記SCRの温度が所定温度超になると、前記NO吸蔵触媒に排ガスを導かずに前記バイパス通路に排ガスを導く、通路切り替え部と、を備えた排気浄化システムに向けられる。 A first form of the present disclosure includes an exhaust passage that is a passage for exhaust gas, a NO x storage catalyst that stores NO x in the exhaust gas guided through the exhaust passage, and a downstream of the NO x storage catalyst in the exhaust passage. provided, the SCR to purify NO x in the exhaust gas, said through exhaust passage in fluid communication with a bypass passage bypassing the the NO x storage catalyst, between the temperature of the SCR is equal to or less than a predetermined temperature, the the NO x storage The exhaust gas is directed to a catalyst, and when the temperature of the SCR exceeds a predetermined temperature, the exhaust gas purification system is provided with a passage switching unit that guides the exhaust gas to the bypass passage without guiding the exhaust gas to the NO x storage catalyst. .

本開示の第2形態は、排気通路を案内されてきた排ガス中のNOを吸蔵するNO吸蔵触媒と、前記排気通路において前記NO吸蔵触媒の下流に設けられ、排ガス中のNOを浄化するSCRと、前記排気通路と流体連通し、前記NO吸蔵触媒をバイパスするバイパス通路と、を備えた排気系において用いられる制御装置であって、前記SCRの温度が所定温度以下の間、前記NO吸蔵触媒に排ガスを導くよう制御する第1切り替え制御部と、前記SCRの温度が所定温度超になると、前記NO吸蔵触媒に排ガスを導かずに前記バイパス通路に排ガスを導くよう制御する第2切り替え制御部と、を備えた制御装置に向けられる。 Second embodiment of the present disclosure, and the NO x storage catalyst for occluding NO x in the exhaust gas which has been guided through the exhaust passage, wherein provided in the exhaust passage downstream of the the NO x storage catalyst, the NO x in the exhaust gas A control device used in an exhaust system comprising an SCR to be purified and a bypass passage that is in fluid communication with the exhaust passage and bypasses the NO x storage catalyst, wherein the temperature of the SCR is equal to or lower than a predetermined temperature, a first switching control unit for controlling so as to guide the exhaust gas to the the NO x storage catalyst, the temperature of the SCR reaches a predetermined temperature greater than the control to direct exhaust gas to the bypass passage not lead to exhaust gas to the the NO x storage catalyst And a second switching control unit.

本開示の各形態によれば、SCRのNO浄化率を向上可能な排気浄化システムおよび制御装置を提供することが出来る。 According to each embodiment of the present disclosure, it is possible to provide an exhaust purification system and a control device that can improve the SCR NO x purification rate.

本開示の排気浄化システムの構成を示す模式図Schematic diagram showing the configuration of the exhaust purification system of the present disclosure 図1の制御装置の処理手順を示すフロー図The flowchart which shows the process sequence of the control apparatus of FIG. 本開示の排気浄化システムの変形例に係る構成を示す模式図Schematic diagram showing a configuration according to a modification of the exhaust purification system of the present disclosure

以下、上記図面を参照して、本開示の排気浄化システムSおよび制御装置17について詳説する。   Hereinafter, the exhaust purification system S and the control device 17 of the present disclosure will be described in detail with reference to the drawings.

<1.定義>
下表1は、本実施形態で使用される頭字語や略語の意味を示す。
<1. Definition>
Table 1 below shows the meanings of acronyms and abbreviations used in the present embodiment.

Figure 2018204495
Figure 2018204495

<2.実施形態>
<2−1.排気浄化システムの全体構成>
図1において、排気浄化システムSは、車両に搭載され、排気通路1と、三方弁3と、NO吸蔵触媒5と、バイパス通路9と、酸化触媒11と、噴射器13と、尿素SCR15と、制御装置17と、を備えている。
<2. Embodiment>
<2-1. Overall configuration of exhaust purification system>
In FIG. 1, an exhaust purification system S is mounted on a vehicle, and includes an exhaust passage 1, a three-way valve 3, a NO x storage catalyst 5, a bypass passage 9, an oxidation catalyst 11, an injector 13, a urea SCR 15, And a control device 17.

排気通路1は、典型的にはディーゼルエンジンのような内燃機関(図示せず)からの排ガスを大気中(車外)へと導く。なお、内燃機関はガソリンエンジンであっても良い。   The exhaust passage 1 typically guides exhaust gas from an internal combustion engine (not shown) such as a diesel engine to the atmosphere (outside the vehicle). The internal combustion engine may be a gasoline engine.

排気通路1には、三方弁3と、NO吸蔵触媒5と、噴射器13と、尿素SCR15とが、排気通路1の上流側から下流に向かって順番に設けられる。 In the exhaust passage 1, a three-way valve 3, a NO x storage catalyst 5, an injector 13, and a urea SCR 15 are provided in order from the upstream side to the downstream side of the exhaust passage 1.

三方弁は、通路切り替え部の例示であって、三方向に流体の出入口を有する弁である。   The three-way valve is an example of a passage switching unit, and has a fluid inlet / outlet port in three directions.

特に、三方弁3は、一つの入口および二つの出口を有する。三方弁3の入口は、排気通路1の上流側と流体連通可能に接続される。二つの出口の一方は、排気通路1の下流側と流体連通可能に、その他方は、後述のバイパス通路9の上流端と流体連通可能に接続される。三方弁3の各出口の開閉は、制御装置17からの制御信号により制御される。   In particular, the three-way valve 3 has one inlet and two outlets. The inlet of the three-way valve 3 is connected to the upstream side of the exhaust passage 1 so as to be in fluid communication. One of the two outlets is connected to the downstream side of the exhaust passage 1 so as to be in fluid communication, and the other is connected to an upstream end of a bypass passage 9 described later so as to be in fluid communication. Opening and closing of each outlet of the three-way valve 3 is controlled by a control signal from the control device 17.

NO吸蔵触媒5は、排気通路1において、三方弁3と、排気通路1とバイパス通路9との合流部分との間に設けられ、低温時(200℃以下程度)から中温時(400℃以下程度)において排ガス中のNOを吸蔵する。ただし、NO吸蔵触媒5の出口では、NOに対するNOの比率(以下、NO/NOという)は、NOにおけるNOの比率(以下、NO/NOという)よりもはるかに小さいことが知られている。 The NO x storage catalyst 5 is provided in the exhaust passage 1 between the three-way valve 3 and the joining portion of the exhaust passage 1 and the bypass passage 9, and from a low temperature (about 200 ° C. or lower) to a middle temperature (400 ° C. or lower). occludes NO x in the exhaust gas to the extent). However, at the outlet of the NO x storage catalyst 5, the ratio of NO 2 to NO x (hereinafter referred to as NO 2 / NO x ) is much smaller than the ratio of NO in NO x (hereinafter referred to as NO / NO x ). It is known.

バイパス通路9は、上述から明らかな通り、排気通路1に設けられたNO吸蔵触媒5をバイパスする。具体的には、バイパス通路9の一方端は、三方弁3の他方の出口と接続され、その他方端は、排気通路1におけるNOx吸蔵触媒5の直ぐ下流側の部分と接続される。 As apparent from the above, the bypass passage 9 bypasses the NO x storage catalyst 5 provided in the exhaust passage 1. Specifically, one end of the bypass passage 9 is connected to the other outlet of the three-way valve 3, and the other end is connected to a portion immediately downstream of the NOx storage catalyst 5 in the exhaust passage 1.

酸化触媒11は、バイパス通路9の途中に設けられ、例えばコージェライトハニカムセラミック製の担体を有する。この担体にも、排ガスの流れ方向に沿って多数セルが形成されている。また、各セルを包囲する隔壁には、例えば貴金属等の触媒が担持またはコートされる。このような酸化触媒11は、排ガス中のNOを酸化して、NOに変換する。ここで、酸化触媒11は、酸化触媒11の出口においてNO/NOと、NO/NOの比率と、が望ましい状態(即ち、両比率が均等)に近づくようにNOをNOに変換する。 The oxidation catalyst 11 is provided in the middle of the bypass passage 9 and has, for example, a support made of cordierite honeycomb ceramic. A large number of cells are also formed in this carrier along the flow direction of the exhaust gas. In addition, the partition wall surrounding each cell is supported or coated with a catalyst such as a noble metal. Such an oxidation catalyst 11 oxidizes NO in the exhaust gas and converts it into NO 2 . Here, the oxidation catalyst 11 converts NO into NO 2 so that the NO 2 / NO x and the ratio of NO / NO x approach the desired state (ie, both ratios are equal) at the outlet of the oxidation catalyst 11. To do.

噴射器13は、例えばDCU(図示せず)の制御下、排ガスの温度が所定温度以上である場合、排気通路1の内部であって尿素SCR15の直ぐ上流側に向けて、前駆体としての尿素水を噴射し、排気通路1を案内されてくる排ガスに供給する。これによって、尿素SCR15の直ぐ上流にてアンモニアが生成される。   For example, when the temperature of the exhaust gas is equal to or higher than a predetermined temperature under the control of a DCU (not shown), the injector 13 has urea as a precursor inside the exhaust passage 1 and immediately upstream of the urea SCR 15. Water is injected and supplied to the exhaust gas guided through the exhaust passage 1. As a result, ammonia is generated immediately upstream of the urea SCR 15.

ここで、DCUは、制御装置17であっても良いし、別の制御装置であっても構わない。   Here, the DCU may be the control device 17 or another control device.

尿素SCR15は、例えばコージェライトハニカムセラミック製の担体を有する。この担体にも、排ガスの流れ方向に沿って多数セルが形成されている。また、各セルを包囲する隔壁には、卑金属酸化物、ゼオライトまたは貴金属等のSCR触媒が担持またはコートされる。   The urea SCR 15 includes, for example, a support made of cordierite honeycomb ceramic. A large number of cells are also formed in this carrier along the flow direction of the exhaust gas. Moreover, the partition wall surrounding each cell is supported or coated with an SCR catalyst such as base metal oxide, zeolite, or noble metal.

尿素SCR15には、排気通路1からのアンモニアおよび排ガスが流入する。その際、排ガス中のNOが、アンモニアと反応することで、窒素と水とに還元される。これによって、排ガス中のNOが無害化される。このようにして生成された水、窒素、二酸化炭素等は、マフラー(図示せず)等を介して、大気中に排出される。 Ammonia and exhaust gas from the exhaust passage 1 flows into the urea SCR 15. At that time, NO x in the exhaust gas reacts with ammonia to be reduced to nitrogen and water. As a result, NO x in the exhaust gas is rendered harmless. The water, nitrogen, carbon dioxide and the like thus generated are discharged into the atmosphere via a muffler (not shown).

制御装置17は、例えば、基板上に、マイコン、不揮発性メモリ、コネクタおよびワーキングメモリ等が実装されたECMで実現される。   The control device 17 is realized by, for example, an ECM in which a microcomputer, a nonvolatile memory, a connector, a working memory, and the like are mounted on a substrate.

コネクタには、例えば、尿素SCR15の温度を検出する温度センサ(図示せず)と接続される。マイコンは、不揮発性メモリ等に予め格納されたプログラムを、ワーキングメモリを用いて実行する。   For example, the connector is connected to a temperature sensor (not shown) that detects the temperature of the urea SCR 15. The microcomputer uses a working memory to execute a program stored in advance in a nonvolatile memory or the like.

<2−2.排気浄化システムの動作>
次に、図1に加え図2を参照して、上記構成の排気浄化システムSの動作を、制御装置17の処理内容を中心に説明する。
<2-2. Operation of exhaust purification system>
Next, referring to FIG. 2 in addition to FIG. 1, the operation of the exhaust purification system S having the above configuration will be described focusing on the processing contents of the control device 17.

内燃機関の始動直後、制御装置17において、マイコンは、三方弁3に制御信号を出力して、三方弁3のバイパス通路9側の出口を閉じて、排気通路1の排ガスが酸化触媒11側に流れないようにする。その結果、内燃機関からの排ガスは、NO吸蔵触媒5に流入して、NOが吸蔵されることになる(ステップS001)。 Immediately after starting the internal combustion engine, in the control device 17, the microcomputer outputs a control signal to the three-way valve 3, closes the outlet on the bypass passage 9 side of the three-way valve 3, and the exhaust gas in the exhaust passage 1 moves to the oxidation catalyst 11 side. Do not flow. As a result, the exhaust gas from the internal combustion engine flows into the NO x storage catalyst 5 and NO x is stored (step S001).

ステップS001の次に、マイコンは、温度センサの出力信号から尿素SCR15の温度が所定温度超であり、かつ尿素SCR15におけるアンモニア吸着量が所定値を超えるか否かを判断する(ステップS003)。ここで、所定温度は、例えば、尿素SCR15の活性温度(約200℃程度)、即ち、尿素SCR15が機能する温度に設計される。また、アンモニア吸着量の検出に関しては、公知技術が用いられる。   After step S001, the microcomputer determines from the output signal of the temperature sensor whether the temperature of the urea SCR 15 exceeds a predetermined temperature and whether the ammonia adsorption amount in the urea SCR 15 exceeds a predetermined value (step S003). Here, the predetermined temperature is designed to be, for example, the activation temperature of the urea SCR 15 (about 200 ° C.), that is, the temperature at which the urea SCR 15 functions. A known technique is used for detecting the ammonia adsorption amount.

ステップS003でNOと判断されると、マイコンは、第1切り替え制御部として機能する。この場合、マイコンは、排ガスを酸化触媒11に流入させる必要が無いとして、三方弁3のバイパス通路9側の出口を閉じる(ステップS005)。なお、初回については、三方弁3の状態がステップS001で設定した状態に維持される。   If NO is determined in step S003, the microcomputer functions as a first switching control unit. In this case, the microcomputer closes the outlet on the bypass passage 9 side of the three-way valve 3 on the assumption that the exhaust gas does not need to flow into the oxidation catalyst 11 (step S005). For the first time, the state of the three-way valve 3 is maintained at the state set in step S001.

ステップS003でYESと判断されると、マイコンは、排ガスを酸化触媒11に流入させた方が良いとして、第2切り替え制御部として機能する。この場合、マイコンは、三方弁3に制御信号を出力して、三方弁3の排気通路1側の出口を閉じる(ステップS007)。これにより、排気通路1の排ガスがNO吸蔵触媒5を流れることなく酸化触媒11側に流れるようにする。また、ステップS007の実行直後(または、ほぼ同時に)、噴射器13は尿素水を排気通路1に噴射する。 If YES is determined in step S003, the microcomputer functions as a second switching control unit because it is better to have the exhaust gas flow into the oxidation catalyst 11. In this case, the microcomputer outputs a control signal to the three-way valve 3 and closes the outlet of the three-way valve 3 on the exhaust passage 1 side (step S007). As a result, the exhaust gas in the exhaust passage 1 flows to the oxidation catalyst 11 side without flowing through the NO x storage catalyst 5. Further, immediately after the execution of step S007 (or almost simultaneously), the injector 13 injects urea water into the exhaust passage 1.

ステップS007の結果、酸化触媒11から流出した排ガスにおいて、NO/NOとNO/NOとは互いに均等に近づくので、尿素SCR15におけるNO浄化率はより好ましい値となる。 As a result of step S007, in the exhaust gas flowing out from the oxidation catalyst 11, NO 2 / NO x and NO / NO x approach each other equally, so the NO x purification rate in the urea SCR 15 becomes a more preferable value.

ステップS005またはステップS007の次に、マイコンは、内燃機関の運転を終了するか否かを判断する(ステップS009)。   After step S005 or step S007, the microcomputer determines whether or not to end the operation of the internal combustion engine (step S009).

ステップS009でNOと判断されると、処理はステップS001に戻る。   If NO is determined in step S009, the process returns to step S001.

それに対し、ステップS009でYESと判断されると、図2の処理は終了する。   On the other hand, if “YES” is determined in the step S009, the process of FIG.

<2−3.排気浄化システムの効果>
上記の通り、NO吸蔵触媒5は低温から中温にかけてNOを吸蔵可能である。マイコンは、尿素SCR15の温度が所定温度以下であれば、尿素SCR15が機能しないため、NO吸蔵触媒5にNOを吸蔵させるように、三方弁3を制御する。
<2-3. Effect of exhaust purification system>
As described above, the NO x storage catalyst 5 can store NO x from a low temperature to a medium temperature. Microcomputer, if the temperature of the urea SCR15 is below a predetermined temperature, since the urea SCR15 does not work, so as to occlude NO x in the NO x storage catalyst 5, and controls the three-way valve 3.

それに対し、マイコンは、尿素SCR15の温度が所定温度超であれば、尿素SCR15におけるNO浄化率を最適化すべく、排ガスが酸化触媒11を通過するよう三方弁3を制御する。 In contrast, microcomputer, if the temperature is a predetermined temperature than the urea SCR 15, in order to optimize the NO x purification rate in the urea SCR 15, controls the three-way valve 3 so that exhaust gas passes through the oxidation catalyst 11.

上記の通り、本排気浄化システムSおよび制御装置17によれば、尿素SCR15の温度が所定温度以下であれば、NO吸蔵触媒5にNOを吸蔵させるが、そうでない場合には、尿素SCR15におけるNO浄化率を最適化されるため、従来の排気浄化システムと比べて尿素SCR15のNO浄化率を向上させることが可能となる。 As described above, according to the exhaust purification system S and the control device 17, if the temperature of the urea SCR 15 is equal to or lower than the predetermined temperature, the NO x storage catalyst 5 stores NO x , but if not, the urea SCR 15 NO to be optimized x purification rate, it is possible to improve the NO x purification rate of the urea SCR15 compared with the conventional exhaust purification system in.

<2−4.付記>
上記説明では、排気浄化システムSは、バイパス通路9上に設けられた酸化触媒11を備えるとして説明した。しかし、これに限らず、排気浄化システムSは、酸化触媒11に代えて、図3に示すように、所謂DPFに酸化触媒を付加して、PMのフィルタ機能と排ガス中のNOの酸化機能を持たせたCSF21を備えていても構わない。
<2-4. Addendum>
In the above description, the exhaust purification system S has been described as including the oxidation catalyst 11 provided on the bypass passage 9. However, the exhaust purification system S is not limited to this, but instead of the oxidation catalyst 11, as shown in FIG. 3, an oxidation catalyst is added to the so-called DPF to provide a PM filter function and an NO oxidation function in exhaust gas. You may have the CSF21 given.

この場合、バイパス通路9は単にNO吸蔵触媒5を短絡するだけの通路となり、CSF21は、排気通路1において噴射器13の直ぐ上流側の部分に設けられることが好ましい。 In this case, the bypass passage 9 is simply a short circuit for the NO x storage catalyst 5, and the CSF 21 is preferably provided immediately upstream of the injector 13 in the exhaust passage 1.

また、ステップS003では、マイコンは、温度センサの出力信号から尿素SCR15の温度を得るとして説明した。しかし、これに限らず、マイコンは、排ガスの温度センサからの出力信号に基づき、尿素SCR15の温度を推定する等しても良い。   In step S003, the microcomputer is described as obtaining the temperature of the urea SCR 15 from the output signal of the temperature sensor. However, the present invention is not limited thereto, and the microcomputer may estimate the temperature of the urea SCR 15 based on an output signal from the exhaust gas temperature sensor.

また、ステップS003では、マイコンは、温度センサの出力信号から尿素SCR15の温度が所定温度超であり、かつ尿素SCR15におけるアンモニア吸着量が所定値を超えるか否かを判断していた。しかし、これは好ましい形態であって、本質的には、マイコンは、ステップS003において、温度センサの出力信号から尿素SCR15の温度が所定温度超か否かを判断するだけでも良い。   In step S003, the microcomputer determines whether the temperature of the urea SCR 15 is higher than a predetermined temperature and whether the ammonia adsorption amount in the urea SCR 15 exceeds a predetermined value from the output signal of the temperature sensor. However, this is a preferable mode, and the microcomputer may merely determine whether or not the temperature of the urea SCR 15 exceeds the predetermined temperature from the output signal of the temperature sensor in step S003.

また、排気通路1と、バイパス通路9との合流点に、もう一つ別の三方弁が設けられていても構わない。   Further, another three-way valve may be provided at the junction of the exhaust passage 1 and the bypass passage 9.

本開示の排気浄化システムおよび制御装置は、SCRのNO浄化率を向上可能な排気浄化システムおよび制御装置を提供することが出来る。 Exhaust gas purification system and a control device of the present disclosure can provide an exhaust gas purification system and a control device capable of improving the NO x purification rate of the SCR.

S 排気浄化システム
1 排気通路
3 通路切り替え部(三方弁)
5 NO吸蔵触媒
9 バイパス通路
11 酸化触媒
15 尿素SCR
17 制御装置
S Exhaust purification system 1 Exhaust passage 3 Passage switching part (three-way valve)
5 NO x storage catalyst 9 Bypass passage 11 Oxidation catalyst 15 Urea SCR
17 Control device

Claims (4)

排ガスの通路である排気通路と、
前記排気通路を案内されてきた排ガス中のNOを吸蔵するNO吸蔵触媒と、
前記排気通路において前記NO吸蔵触媒の下流に設けられ、排ガス中のNOを浄化するSCRと、
前記通路と流体連通し、前記NO吸蔵触媒をバイパスするバイパス通路と、
前記SCRの温度が所定温度以下の間、前記NO吸蔵触媒に排ガスを導き、前記SCRの温度が所定温度超になると、前記NO吸蔵触媒に排ガスを導かずに前記バイパス通路に排ガスを導く、通路切り替え部と、
を備えた排気浄化システム。
An exhaust passage which is a passage for exhaust gas;
A NO x storage catalyst for storing NO x in the exhaust gas guided through the exhaust passage;
An SCR provided downstream of the NO x storage catalyst in the exhaust passage and purifying NO x in the exhaust gas;
A bypass passage in fluid communication with the passage and bypassing the NO x storage catalyst;
While the temperature of the SCR is equal to or lower than a predetermined temperature, exhaust gas is guided to the NO x storage catalyst. When the temperature of the SCR exceeds a predetermined temperature, exhaust gas is guided to the bypass passage without introducing exhaust gas to the NO x storage catalyst. A passage switching unit;
Exhaust gas purification system with
前記所定温度は前記SCRの活性温度である、
請求項1に記載の排気浄化システム。
The predetermined temperature is an activation temperature of the SCR.
The exhaust purification system according to claim 1.
前記バイパス通路に設けられて、排ガス中のNOを酸化する酸化触媒を、さらに備え、
前記通路切り替え部は、前記SCRの温度が所定温度超になると、前記バイパス通路に設けられた前記酸化触媒に排ガスを導く、
請求項1に記載の排気浄化システム。
An oxidation catalyst that is provided in the bypass passage and oxidizes NO in the exhaust gas;
The passage switching unit guides exhaust gas to the oxidation catalyst provided in the bypass passage when the temperature of the SCR exceeds a predetermined temperature.
The exhaust purification system according to claim 1.
排気通路を案内されてきた排ガス中のNOを吸蔵するNO吸蔵触媒と、前記排気通路において前記NO吸蔵触媒の下流に設けられ、排ガス中のNOを浄化するSCRと、前記排気通路と流体連通し、前記NO吸蔵触媒をバイパスするバイパス通路と、を備えた排気系において用いられる制御装置であって、
前記SCRの温度が所定温度以下の間、前記NO吸蔵触媒に排ガスを導くよう制御する第1切り替え制御部と、
前記SCRの温度が所定温度超になると、前記NO吸蔵触媒に排ガスを導かずに前記バイパス通路に排ガスを導くよう制御する第2切り替え制御部と、
を備えた制御装置。
An NO x storage catalyst for storing NO x in the exhaust gas guided through the exhaust passage, an SCR provided downstream of the NO x storage catalyst in the exhaust passage, for purifying NO x in the exhaust gas, and the exhaust passage A control device used in an exhaust system comprising a bypass passage that is in fluid communication with and bypasses the NO x storage catalyst,
A first switching control unit configured to control exhaust gas to be guided to the NO x storage catalyst while the temperature of the SCR is equal to or lower than a predetermined temperature;
A second switching control unit configured to control exhaust gas to the bypass passage without introducing exhaust gas to the NO x storage catalyst when the temperature of the SCR exceeds a predetermined temperature;
A control device comprising:
JP2017109234A 2017-06-01 2017-06-01 Exhaust emission control system and control device Pending JP2018204495A (en)

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