JP2017031940A - Exhaust emission control system for internal combustion engine, internal combustion engine and exhaust emission control method for internal combustion engine - Google Patents

Exhaust emission control system for internal combustion engine, internal combustion engine and exhaust emission control method for internal combustion engine Download PDF

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JP2017031940A
JP2017031940A JP2015155088A JP2015155088A JP2017031940A JP 2017031940 A JP2017031940 A JP 2017031940A JP 2015155088 A JP2015155088 A JP 2015155088A JP 2015155088 A JP2015155088 A JP 2015155088A JP 2017031940 A JP2017031940 A JP 2017031940A
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exhaust gas
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combustion engine
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貴幸 古川
Takayuki Furukawa
貴幸 古川
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control system for an internal combustion engine, the internal combustion engine and an exhaust emission control method for the internal combustion engine that can inhibit ammonia slip even in an operating condition of the engine where there is a possibility of the ammonia slip, can suppress an increase in NOx emission to the atmosphere and can highly efficiently and continuously eliminate NOx.SOLUTION: A selective reduction type catalyst device 13 is provided in an exhaust passage 11 of an internal combustion engine, and an outside air supply device 30 for supplying outside air OA to cool exhaust gas G made to flow into the selective reduction type catalyst device 13 is provided around an exhaust pipe 11a constituting the exhaust passage 11. When a temperature T of the exhaust gas G made to flow into the selective reduction type catalyst device 13 is a determination temperature threshold value T1 or higher, the outside air supply device 30 is actuated to cool the exhaust gas G flowing into the selective reduction type catalyst device 13 by using the outside air OA, so that the temperature of the exhaust gas G becomes lower than the determination temperature threshold value T1.SELECTED DRAWING: Figure 1

Description

本発明は、内燃機関の排気通路に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、内燃機関、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, an internal combustion engine, and an exhaust gas purification method for an internal combustion engine, each of which includes a selective reduction catalyst device in an exhaust passage of the internal combustion engine.

一般的に、車両に搭載されるディーゼルエンジン等の内燃機関には、排気ガスに含まれる窒素酸化物（ＮＯｘ）、炭化水素（ＨＣ）、一酸化炭素（ＣＯ）等の浄化対象成分を浄化処理するために、排気通路に排気ガス浄化システムが設けられる。この排気ガス浄化システムは、酸化触媒装置（ＤＯＣ）、微粒子捕集装置（ＣＳＦ）、選択還元型触媒装置（ＳＣＲ）等の装置が配設されて構成されるシステムである。   Generally, an internal combustion engine such as a diesel engine mounted on a vehicle purifies a component to be purified such as nitrogen oxide (NOx), hydrocarbon (HC), carbon monoxide (CO) contained in exhaust gas. Therefore, an exhaust gas purification system is provided in the exhaust passage. This exhaust gas purification system is a system in which devices such as an oxidation catalyst device (DOC), a particulate collection device (CSF), and a selective catalytic reduction device (SCR) are arranged.

選択還元型触媒装置は、内燃機関から排出される窒素酸化物（ＮＯｘ）を、尿素水より生成したアンモニア（ＮＨ3）を用いて、窒素と水に還元する装置である。この尿素水は、選択還元型触媒装置の前段の排気通路に配設した尿素水供給装置より供給されるのが一般的である。 The selective catalytic reduction apparatus is an apparatus that reduces nitrogen oxide (NOx) discharged from an internal combustion engine into nitrogen and water using ammonia (NH 3 ) generated from urea water. This urea water is generally supplied from a urea water supply device disposed in the exhaust passage upstream of the selective catalytic reduction device.

尿素水供給装置より排気通路内に噴射された尿素水は、蒸発、拡散などを経て、アンモニアを生成する。このアンモニアは、選択還元型触媒装置の内部の触媒表面に吸着され、内燃機関から排出された窒素酸化物とこの触媒表面上で反応して、窒素と水を生成する。選択還元型触媒装置へのアンモニア吸着量は、選択還元型触媒装置の温度に依存し、選択還元型触媒装置の温度が高温になるにつれて低減される。   The urea water injected into the exhaust passage from the urea water supply device generates ammonia through evaporation, diffusion, and the like. This ammonia is adsorbed on the catalyst surface inside the selective catalytic reduction device, and reacts with nitrogen oxides discharged from the internal combustion engine on the catalyst surface to generate nitrogen and water. The amount of ammonia adsorbed on the selective catalytic reduction device depends on the temperature of the selective catalytic reduction device, and decreases as the temperature of the selective catalytic reduction device increases.

選択還元型触媒装置でＮＯｘを効率的に還元するためには、選択還元型触媒装置の内部に常時必要十分な量のアンモニアを吸着しておくことが望ましいが、内燃機関の運転状態が急変して（過渡状態となり）、排気ガスの温度が急上昇すると、選択還元型触媒装置のアンモニア吸着量が大幅に低減されて、選択還元型触媒装置から放出された大量のアンモニアが大気に排出される（アンモニアスリップ）懸念がある。   In order to efficiently reduce NOx with the selective catalytic reduction device, it is desirable to always adsorb a necessary and sufficient amount of ammonia inside the selective catalytic reduction device, but the operating state of the internal combustion engine changes suddenly. Therefore, when the exhaust gas temperature rises rapidly, the ammonia adsorption amount of the selective catalytic reduction device is greatly reduced, and a large amount of ammonia released from the selective catalytic reduction device is discharged to the atmosphere ( Ammonia slip) is a concern.

従来技術では、このアンモニアスリップを抑制するために、尿素水供給装置から供給される尿素水の噴射量を制限したり、または、尿素水の噴射を停止したりするなどの措置を行っていた。しかしながら、これらの措置を行った後、内燃機関の運転条件がさらに急変して、大量のＮＯｘが内燃機関より排出されたときに、この大量のＮＯｘを浄化するために必要十分な量のアンモニアを即時に選択還元型触媒装置に供給することができず、浄化しきれない大量のＮＯｘが大気に放出される懸念があった。   In the prior art, in order to suppress this ammonia slip, measures such as limiting the injection amount of urea water supplied from the urea water supply device or stopping the injection of urea water have been taken. However, after these measures are taken, when the operating conditions of the internal combustion engine change abruptly and a large amount of NOx is exhausted from the internal combustion engine, a sufficient amount of ammonia necessary to purify this large amount of NOx is removed. There was a concern that a large amount of NOx that could not be purified and could not be immediately supplied to the selective catalytic reduction device was released to the atmosphere.

また、これに関連して、排気管の途中で尿素水供給装置とＳＣＲ触媒装置との間のエア供給位置に冷却媒体である外気を流入し、排気ガスの温度及びＳＣＲ触媒の触媒温度を低下させる内燃機関の排気ガス浄化装置が提案されている（例えば、特許文献１参照）。   In this connection, outside air as a cooling medium flows into the air supply position between the urea water supply device and the SCR catalyst device in the middle of the exhaust pipe, and the temperature of the exhaust gas and the catalyst temperature of the SCR catalyst are lowered. There has been proposed an exhaust gas purifying device for an internal combustion engine (see, for example, Patent Document 1).

しかしながら、上記の内燃機関の排気ガス浄化装置では、排気ガスの温度及びＳＣＲ触媒装置の温度を低下させるために、排気管の内部に大量の外気を流入する必要があるため、排気通路における圧力損失の増加の影響が懸念されるとともに、排気ガスが薄まるので、選択還元型触媒装置のＮＯｘの浄化性能への影響も懸念される。   However, in the exhaust gas purifying apparatus for an internal combustion engine described above, in order to reduce the temperature of the exhaust gas and the temperature of the SCR catalyst apparatus, it is necessary to flow a large amount of outside air into the exhaust pipe. There is a concern about the effect of this increase, and since the exhaust gas is diluted, there is also a concern about the effect on the NOx purification performance of the selective catalytic reduction device.

特開２００３−３２８７２４号公報JP 2003-328724 A

本発明は、上記のことを鑑みてなされたものであり、その目的は、内燃機関の排気通路に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関し、特に、アンモニアスリップの懸念があるようなエンジンの運転条件でも、アンモニアスリップを抑制することができるとともに、大気へのＮＯｘの排出量の増加を抑制することができ、高効率かつ継続的なＮＯｘ浄化を行うことができる内燃機関の排気ガス浄化システム、内燃機関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。   The present invention has been made in view of the above, and an object of the present invention relates to an exhaust gas purification system for an internal combustion engine configured to include a selective reduction catalyst device in an exhaust passage of the internal combustion engine, and in particular, an ammonia slip. In addition to being able to suppress ammonia slip even under engine operating conditions where there is concern, it is possible to suppress an increase in NOx emissions into the atmosphere, and to perform highly efficient and continuous NOx purification. An exhaust gas purification system for an internal combustion engine, an internal combustion engine, and an exhaust gas purification method for the internal combustion engine are provided.

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、前記選択還元型触媒装置より上流側の前記排気通路に、前記選択還元型触媒装置に流入する排気ガスの温度を検出する排気温度検出装置を設けるとともに、前記排気通路を構成する排気管の周囲に外気を供給して前記選択還元型触媒装置に流入する排気ガスを冷却する外気供給装置を設け、当該排気ガス浄化システムを制御する制御装置が、前記排気温度検出装置の検出値が予め設定された判定温度閾値以上のときには、排気ガスの温度が前記判定温度閾値未満になるように、前記外気供給装置を作動させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却し、前記排気温度検出装置の検出値が前記判定温度閾値未満のときには、前記外気供給装置を停止させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却しないように構成される。   In order to achieve the above object, an exhaust gas purification system for an internal combustion engine according to the present invention is an exhaust gas purification system for an internal combustion engine comprising a selective reduction catalyst device in an exhaust passage of the internal combustion engine. An exhaust temperature detection device for detecting the temperature of the exhaust gas flowing into the selective reduction catalyst device is provided in the exhaust passage upstream from the catalyst device, and outside air is supplied around the exhaust pipe constituting the exhaust passage. Provided with an outside air supply device that cools the exhaust gas flowing into the selective catalytic reduction device, and the control device that controls the exhaust gas purification system has a detection value of the exhaust temperature detection device equal to or higher than a preset determination temperature threshold value In this case, the outside air supply device is operated so that the temperature of the exhaust gas becomes less than the judgment temperature threshold value, and the exhaust gas flowing into the selective catalytic reduction catalyst device is discharged outside. When the detected value of the exhaust temperature detection device is less than the determination temperature threshold, the outside air supply device is stopped and the exhaust gas flowing into the selective catalytic reduction device is not cooled by outside air. The

この判定温度閾値は、選択還元型触媒装置に流入する排気ガスの温度がこの判定温度閾値より高温になると、選択還元型触媒装置内部のアンモニア吸着量が大幅に低減されて、大量のアンモニアが選択還元型触媒装置より大気に排出される（アンモニアスリップ）懸念があるものとして、予め実験等により設定される温度閾値であり、例えば、３５０℃〜４５０℃に設定される。従来技術では、排気ガスの温度が判定温度閾値より高温になると、アンモニアスリップを抑制すべく、選択還元型触媒装置の入口に配設した尿素水供給装置からの尿素水の噴射量を制限したり、または、尿素水の噴射を停止したりする措置をとっていた。   This judgment temperature threshold is selected when the temperature of the exhaust gas flowing into the selective catalytic reduction device becomes higher than this judgment temperature threshold, the amount of ammonia adsorbed inside the selective catalytic reduction device is greatly reduced, and a large amount of ammonia is selected. It is a temperature threshold value set in advance by experiments or the like, for example, which is set to 350 ° C. to 450 ° C., as being feared of being discharged from the reduction catalyst device to the atmosphere (ammonia slip). In the prior art, when the temperature of the exhaust gas becomes higher than the determination temperature threshold, the injection amount of urea water from the urea water supply device disposed at the inlet of the selective catalytic reduction catalyst device is limited in order to suppress ammonia slip. Or measures to stop the injection of urea water were taken.

これに対し、本発明では、選択還元型触媒装置に流入する排気ガスの温度が判定温度閾値以上のときに、排気ガスの温度が判定温度閾値未満になるように、外気供給装置を作動させて、選択還元型触媒装置に流入する排気ガスを外気で冷却することで、選択還元型触媒装置の温度の上昇を抑制することができるので、選択還元型触媒装置内部のアンモニア吸着量の低減を抑制することができる。   In contrast, in the present invention, when the temperature of the exhaust gas flowing into the selective catalytic reduction device is equal to or higher than the determination temperature threshold, the outside air supply device is operated so that the temperature of the exhaust gas becomes less than the determination temperature threshold. By cooling the exhaust gas flowing into the selective catalytic reduction device with the outside air, the temperature increase of the selective catalytic reduction device can be suppressed, so that the reduction in the amount of ammonia adsorbed inside the selective catalytic reduction device is suppressed. can do.

したがって、この構成によれば、アンモニアスリップの懸念があるようなエンジンの運転条件で、選択還元型触媒装置内部のアンモニア吸着量の低減を抑制して、選択還元型触媒装置から放出されるアンモニアの量を低減することができるので、従来行っていた、尿素水の噴射量制限または尿素水の噴射停止の措置をとらなくても、通常の尿素水噴射制御を維持したまま、アンモニアスリップを抑制することができる。   Therefore, according to this configuration, it is possible to suppress the decrease in the amount of ammonia adsorbed inside the selective catalytic reduction device under the engine operating conditions where there is a concern of ammonia slip, and to reduce the amount of ammonia released from the selective catalytic reduction device. Since the amount can be reduced, ammonia slip can be suppressed while maintaining normal urea water injection control without taking measures to limit the injection amount of urea water or stop the injection of urea water, which has been conventionally performed. be able to.

また、尿素水の噴射量制限または噴射停止の措置が不要となるので、選択還元型触媒装置への尿素水（アンモニア）の供給量を常時十分に確保することができる。そのため、大気へのＮＯｘの排出量の増加を抑制することができ、高効率かつ継続的なＮＯｘ浄化を行うことができる。   In addition, since it is not necessary to limit the injection amount of urea water or stop injection, it is possible to always ensure a sufficient supply amount of urea water (ammonia) to the selective catalytic reduction device. Therefore, an increase in the amount of NOx discharged to the atmosphere can be suppressed, and highly efficient and continuous NOx purification can be performed.

また、排気管の外部より外気を供給しているので、排気通路における圧力損失の増加の影響や、選択還元型触媒装置のＮＯｘの浄化性能への影響も発生しない。   Further, since the outside air is supplied from the outside of the exhaust pipe, there is no influence of an increase in pressure loss in the exhaust passage and no influence on the NOx purification performance of the selective catalytic reduction device.

すなわち、アンモニアスリップの懸念があるようなエンジンの運転条件でも、流入する排気ガスの温度調整を介しての選択還元型触媒装置の温度調整を外気を用いて行うことで、アンモニアスリップを抑制することができるとともに、大気へのＮＯｘの排出量の増加を抑制することができ、高効率かつ継続的なＮＯｘ浄化を行うことができる。   In other words, even under engine operating conditions where there is a concern about ammonia slip, the temperature of the selective catalytic reduction catalyst device is adjusted using outside air through temperature adjustment of the inflowing exhaust gas, thereby suppressing ammonia slip. In addition, an increase in the amount of NOx discharged to the atmosphere can be suppressed, and highly efficient and continuous NOx purification can be performed.

また、より具体的には、上記の内燃機関の排気ガス浄化システムにおいて、前記外気供給装置を、前記排気管を内管として、前記選択還元型触媒装置が備えられる箇所周辺の前記内管の外部に、前記選択還元型触媒装置を保温する外管又はケースを設けて２重構造とした２重構造部と、前記内管と前記外管又はケースの間に外気を導入するために、前記外管又はケースに設けた外気導入孔と、該外気導入孔からの外気の導入の有無を切り替えるために、前記外気導入孔に設けた開閉装置とで構成される。   More specifically, in the exhaust gas purification system for an internal combustion engine, the outside air supply device may be an outside of the inner pipe around the location where the selective reduction catalyst device is provided with the exhaust pipe as an inner pipe. In order to introduce outside air between the inner tube and the outer tube or the case, a double structure part having a double structure by providing an outer tube or case for keeping the selective reduction catalyst device warm is provided. An outside air introduction hole provided in the pipe or the case and an opening / closing device provided in the outside air introduction hole for switching whether or not the outside air is introduced from the outside air introduction hole.

この構成によれば、選択還元型触媒装置の温度が判定温度閾値未満であるときには、２重構造部により選択還元型触媒装置の保温性能を向上させることで、選択還元型触媒装置に担持した触媒の温度を活性化温度範囲内に維持することができるとともに、選択還元型触媒装置の温度が判定温度閾値以上であるときには、選択還元型触媒装置に流入する排気ガスを外気で確実に冷却することで、上記の作用効果（アンモニアスリップの抑制、高効率かつ継続的なＮＯｘ浄化）を確実に奏することができる。   According to this configuration, when the temperature of the selective reduction catalyst device is lower than the determination temperature threshold, the temperature of the selective reduction catalyst device is improved by the double structure portion, so that the catalyst carried on the selective reduction catalyst device. Can be maintained within the activation temperature range, and when the temperature of the selective catalytic reduction device is equal to or higher than the determination temperature threshold, the exhaust gas flowing into the selective catalytic reduction device is reliably cooled with outside air. Thus, the above-described operational effects (suppression of ammonia slip, highly efficient and continuous NOx purification) can be reliably achieved.

また、上記の内燃機関の排気ガス浄化システムを搭載した内燃機関は、上記の内燃機関の排気ガス浄化システムと同様の作用効果を奏することができる。   An internal combustion engine equipped with the exhaust gas purification system for an internal combustion engine can achieve the same effects as the exhaust gas purification system for the internal combustion engine.

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選択還元型触媒装置を備えるとともに、前記排気通路を構成する排気管の周囲に外気を供給して前記選択還元型触媒装置に流入する排気ガスを冷却する外気供給装置を設け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に流入する排気ガスの温度が予め設定された判定温度閾値以上のときには、排気ガスの温度が前記判定温度閾値未満になるように、前記外気供給装置を作動させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却し、前記選択還元型触媒装置に流入する排気ガスの温度が前記判定温度閾値未満のときには、前記外気供給装置を停止させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却しないようにすることを特徴とする方法である。   In addition, an exhaust gas purification method for an internal combustion engine of the present invention for achieving the above object includes a selective reduction type catalyst device in an exhaust passage of the internal combustion engine, and external air around an exhaust pipe constituting the exhaust passage. In the exhaust gas purification method for an internal combustion engine configured to include an outside air supply device that supplies and cools the exhaust gas flowing into the selective reduction catalyst device, the temperature of the exhaust gas flowing into the selective reduction catalyst device is previously set. When the temperature is equal to or higher than the set judgment temperature threshold, the outside air supply device is operated so that the temperature of the exhaust gas becomes less than the judgment temperature threshold, and the exhaust gas flowing into the selective catalytic reduction device is cooled with outside air. When the temperature of the exhaust gas flowing into the selective reduction catalyst device is less than the determination temperature threshold, the outside air supply device is stopped and the exhaust gas flowing into the selective reduction catalyst device is stopped. Which is a method characterized by so as not to cool in ambient air.

また、上記の内燃機関の排気ガス浄化方法は、前記外気供給装置を、前記排気管を内管として、前記選択還元型触媒装置が備えられる箇所周辺の前記内管の外部に、前記選択還元型触媒装置を保温する外管又はケースを設けて２重構造とした２重構造部と、前記内管と前記外管又はケースの間に外気を導入するために、前記外管又はケースに設けた外気導入孔と、該外気導入孔からの外気の導入の有無を切り替えるために、前記外気導入孔に設けた開閉装置とで構成するとともに、前記選択還元型触媒装置に流入する排気ガスの温度が前記判定温度閾値以上のときには、排気ガスの温度が前記判定温度閾値未満になるように、前記開閉装置を開状態とし、前記選択還元型触媒装置に流入する排気ガスを外気で冷却し、前記選択還元型触媒装置に流入する排気ガスの温度が前記判定温度閾値未満のときには、前記開閉装置を閉状態とし、前記選択還元型触媒装置に流入する排気ガスを外気で冷却しないようにすることを特徴とする方法である。   Further, in the exhaust gas purification method for an internal combustion engine, the external air supply device is used as the selective reduction type outside the inner pipe around the place where the selective reduction type catalytic device is provided with the exhaust pipe as an inner pipe. Provided in the outer tube or case in order to introduce outside air between the inner tube and the outer tube or case, and a double structure part having a double structure by providing an outer tube or case for keeping the catalyst device warm In order to switch between the outside air introduction hole and the presence / absence of introduction of outside air from the outside air introduction hole, an opening / closing device provided in the outside air introduction hole is used, and the temperature of the exhaust gas flowing into the selective catalytic reduction catalyst device is When the temperature is equal to or higher than the determination temperature threshold, the opening / closing device is opened so that the temperature of the exhaust gas is lower than the determination temperature threshold, the exhaust gas flowing into the selective catalytic reduction device is cooled with outside air, and the selection is performed. Reduction-type catalytic equipment When the temperature of the inflowing exhaust gas is lower than the determination temperature threshold, the opening / closing device is closed, and the exhaust gas flowing into the selective catalytic reduction device is not cooled by outside air. .

これらの方法によれば、上記の内燃機関の排気ガス浄化方法と同様の作用効果を奏することができる。   According to these methods, the same effects as the exhaust gas purification method for an internal combustion engine can be obtained.

本発明の内燃機関の排気ガス浄化システム、内燃機関、及び内燃機関の排気ガス浄化方法によれば、アンモニアスリップの懸念があるようなエンジンの運転条件でも、選択還元型触媒装置の温度制御を外気を用いて行うことで、アンモニアスリップを抑制することができるとともに、大気へのＮＯｘの排出量の増加を抑制することができ、高効率かつ継続的なＮＯｘ浄化を行うことができる。   According to the exhaust gas purification system for an internal combustion engine, the internal combustion engine, and the exhaust gas purification method for an internal combustion engine of the present invention, the temperature control of the selective catalytic reduction catalyst device can be controlled even under the operating conditions of the engine that may cause ammonia slip. By using this, ammonia slip can be suppressed, and an increase in the amount of NOx discharged to the atmosphere can be suppressed, so that highly efficient and continuous NOx purification can be performed.

本発明に係る実施の形態の内燃機関の排気ガス浄化システムの構成を模式的に示す図である。It is a figure showing typically composition of an exhaust-gas purification system of an internal-combustion engine of an embodiment concerning the present invention. 従来技術に係る内燃機関の排気ガス浄化システムの構成を模式的に示す図である。It is a figure which shows typically the structure of the exhaust-gas purification system of the internal combustion engine which concerns on a prior art.

以下、本発明に係る実施の形態の内燃機関の排気ガス浄化システム、内燃機関、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。なお、本発明に係る実施の形態の内燃機関は、本発明に係る実施の形態の内燃機関の排気ガス浄化システム１を備えて構成され、後述する内燃機関の排気ガス浄化システム１が奏する作用効果と同様の作用効果を奏することができる。   Hereinafter, an exhaust gas purification system for an internal combustion engine, an internal combustion engine, and an exhaust gas purification method for the internal combustion engine according to embodiments of the present invention will be described with reference to the drawings. The internal combustion engine of the embodiment according to the present invention is configured to include the exhaust gas purification system 1 of the internal combustion engine of the embodiment according to the present invention, and the effects obtained by the exhaust gas purification system 1 of the internal combustion engine described later are provided. The same operational effects can be achieved.

図１に示すように、本発明に係る実施の形態の内燃機関の排気ガス浄化システム１は、エンジン（内燃機関）（図示しない）の排気通路１１に、尿素水供給装置１２、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。この選択還元型触媒装置１３は、上流側の排気通路１１に配設される酸化触媒装置（ＤＯＣ）（図示しない）や微粒子捕集装置（ＣＳＦ）（図示しない）、下流側の排気通路１１に配設されるアンモニアスリップ触媒装置（ＡＳＣ）１４とともに、排気ガス浄化装置を構成し、この排気ガス浄化装置で浄化処理された排気ガスＧｃはマフラー等を経由して大気へ放出される。また、尿素水供給装置１２は、エンジンの運転状態に基づいて、選択還元型触媒装置１３に向けて尿素水Ｕを噴射する装置であり、噴射された尿素水Ｕは、排気ガスＧの熱により加水分解されてアンモニア（ＮＨ3）を生成し、このアンモニアが選択還元型触媒装置１３に供給されて吸着する。 As shown in FIG. 1, an exhaust gas purification system 1 for an internal combustion engine according to an embodiment of the present invention includes a urea water supply device 12 and a selective reduction catalyst in an exhaust passage 11 of an engine (internal combustion engine) (not shown). This is a system configured with a device (SCR) 13. The selective catalytic reduction device 13 is connected to an oxidation catalyst device (DOC) (not shown) or a particulate collection device (CSF) (not shown) disposed in the upstream exhaust passage 11, or to the downstream exhaust passage 11. Together with the ammonia slip catalyst device (ASC) 14 disposed, an exhaust gas purification device is configured, and the exhaust gas Gc purified by the exhaust gas purification device is released to the atmosphere via a muffler or the like. The urea water supply device 12 is a device that injects urea water U toward the selective reduction catalyst device 13 based on the operating state of the engine. The injected urea water U is generated by the heat of the exhaust gas G. It is hydrolyzed to produce ammonia (NH 3 ), and this ammonia is supplied to and adsorbed to the selective catalytic reduction device 13.

また、選択還元型触媒装置１３より上流側の排気通路１１に、選択還元型触媒装置１３に流入する排気ガスＧの温度Ｔを検出する排気温度センサ（排気温度検出装置）２０を設ける。この排気温度センサ２０の信号は、予め設定された制御時間毎に、後述する制御装置４０に送信される。   Further, an exhaust temperature sensor (exhaust temperature detection device) 20 for detecting the temperature T of the exhaust gas G flowing into the selective reduction catalyst device 13 is provided in the exhaust passage 11 upstream of the selective reduction catalyst device 13. The signal of the exhaust temperature sensor 20 is transmitted to a control device 40 described later at every preset control time.

また、本発明の内燃機関の排気ガス浄化システム１を制御する制御装置４０が備えられる。この制御装置４０は、予め設定された制御時間毎に、排気温度センサ２０等の各種センサより送信された信号に基づいて、予め設定された制御時間毎に、各種センサの検出値を算出するとともに、必要な検出値のデータ（通常は、最新の検出値のデータ）を記憶する。この制御装置４０は、通常は、エンジンの運転状態全般を制御するエンジンコントロールユニット（ＥＣＵ）に組み込まれるが、独立して設けてもよい。   Moreover, the control apparatus 40 which controls the exhaust-gas purification system 1 of the internal combustion engine of this invention is provided. The control device 40 calculates detection values of various sensors for each preset control time based on signals transmitted from various sensors such as the exhaust temperature sensor 20 for each preset control time. The necessary detection value data (usually the latest detection value data) is stored. The control device 40 is normally incorporated in an engine control unit (ECU) that controls the overall operating state of the engine, but may be provided independently.

なお、本発明の内燃機関の排気ガス浄化システム１に関し、上記で説明した構成及び制御については、図２に示す従来技術の内燃機関の排気ガス浄化システム１Ｘと同様である。   Regarding the exhaust gas purification system 1 for an internal combustion engine of the present invention, the configuration and control described above are the same as those of the exhaust gas purification system 1X for the internal combustion engine of the prior art shown in FIG.

そして、本発明の内燃機関の排気ガス浄化システム１では、選択還元型触媒装置１３に流入する排気ガスＧを、排気通路１１を構成する排気管１１ａの周囲に、言い換えれば、排気管１１ａ超しに外気ＯＡを供給して冷却する外気供給装置３０を設けて構成する。   In the exhaust gas purification system 1 for an internal combustion engine according to the present invention, the exhaust gas G flowing into the selective catalytic reduction device 13 is disposed around the exhaust pipe 11a constituting the exhaust passage 11, in other words, beyond the exhaust pipe 11a. An outside air supply device 30 that supplies and cools outside air OA is provided.

この外気供給装置３０は、より具体的には、排気管１１ａを内管として、選択還元型触媒装置１３を備えられる箇所周辺の内管１１ａの外部に、選択還元型触媒装置１３を保温する外管１１ｂを設けて２重構造とした２重構造部３０ａと、内管１１ａと外管１１ｂの間に外気ＯＡを導入するために、外管１１ｂに設けた外気導入孔３０ｂと、この外気導入孔３０ｂからの外気ＯＡの導入の有無を切り替えるために、外気導入孔３０ｂに設けたシャッター（開閉装置）３０ｃとで構成する。なお、外管１１ｂの代わりに内管１１ａを囲うケース（筺体）を設けてもよい。また、外気の代わりに、この内燃機関を搭載している車両の圧縮空気タンクからの圧縮空気を用いて内管１１ａの外周部を冷却してもよい。   More specifically, the outside air supply device 30 has an exhaust pipe 11a as an inner pipe, and an external pipe that keeps the selective reduction catalyst apparatus 13 outside the inner pipe 11a around the place where the selective reduction catalyst apparatus 13 is provided. A double structure portion 30a having a double structure by providing the tube 11b, an outside air introduction hole 30b provided in the outer tube 11b for introducing the outside air OA between the inner tube 11a and the outer tube 11b, and this outside air introduction; In order to switch the presence / absence of introduction of the outside air OA from the hole 30b, a shutter (opening / closing device) 30c provided in the outside air introduction hole 30b is used. In addition, you may provide the case (casing) which encloses the inner pipe | tube 11a instead of the outer pipe | tube 11b. Moreover, you may cool the outer peripheral part of the inner pipe | tube 11a using the compressed air from the compressed air tank of the vehicle carrying this internal combustion engine instead of external air.

また、図１では、外気導入孔３０ｂを、排気ガスＧの進行方向と平行となる位置に設けているが、排気ガスＧの進行方向に傾斜又は垂直となる位置に設けてもよい。   In FIG. 1, the outside air introduction hole 30 b is provided at a position parallel to the traveling direction of the exhaust gas G, but may be provided at a position inclined or perpendicular to the traveling direction of the exhaust gas G.

また、２重構造部３０ａを選択還元型触媒装置１３より下流側のアンモニアスリップ触媒装置１４にまで拡大して、アンモニアスリップ触媒装置１４も保温するとともに、内管１１ａと外管１１ｂの間に流入した外気ＯＡを、選択還元型触媒装置１３及びアンモニアスリップ触媒装置１４を通過して、外部に放出する方が好ましい。さらには、２重構造部３０ａを選択還元型触媒装置１３より上流側の酸化触媒装置及び微粒子捕集装置にまで拡大して、排気ガス浄化装置全体を保温する構成とすると、商品性を向上させることができるので、好ましい。   Further, the double structure portion 30a is expanded to the ammonia slip catalyst device 14 on the downstream side of the selective reduction catalyst device 13, and the ammonia slip catalyst device 14 is also kept warm and flows between the inner tube 11a and the outer tube 11b. It is preferable to discharge the outside air OA that has passed through the selective catalytic reduction catalyst device 13 and the ammonia slip catalyst device 14 to the outside. Furthermore, if the double structure portion 30a is expanded to the oxidation catalyst device and the particulate collection device upstream of the selective catalytic reduction device 13, the entire exhaust gas purification device is kept warm, thereby improving the commercial value. This is preferable.

そして、制御装置４０が、排気温度センサ２０の検出値Ｔが予め設定された判定温度閾値Ｔ１以上のときには、排気ガスＧの温度（排気温度センサ２０の検出値Ｔ）が判定温度閾値Ｔ１未満になるように、外気供給装置３０を作動させ、選択還元型触媒装置１３に流入する排気ガスＧを外気ＯＡで冷却する。一方、排気温度センサ２０の検出値Ｔが判定温度閾値Ｔ１未満のときには、外気供給装置３０を停止させ、選択還元型触媒装置１３に流入する排気ガスＧを外気で冷却しないように構成する。   When the detection value T of the exhaust gas temperature sensor 20 is equal to or higher than a preset determination temperature threshold value T1, the control device 40 determines that the temperature of the exhaust gas G (the detection value T of the exhaust gas temperature sensor 20) is less than the determination temperature threshold value T1. Thus, the outside air supply device 30 is operated, and the exhaust gas G flowing into the selective catalytic reduction catalyst device 13 is cooled by the outside air OA. On the other hand, when the detected value T of the exhaust temperature sensor 20 is less than the determination temperature threshold value T1, the outside air supply device 30 is stopped and the exhaust gas G flowing into the selective catalytic reduction device 13 is not cooled by outside air.

なお、外気供給装置３０の作動とは、シャッター３０ｃを開状態として、外気導入孔３０ｂより外気ＯＡを内管１１ａと外管１１ｂの間に供給することである。一方、外気供給装置３０の停止とは、シャッター３０ｃを閉状態として、外気導入孔３０ｂより外気ＯＡを内管１１ａと外管１１ｂの間に供給しないことである。   The operation of the outside air supply device 30 is to supply the outside air OA between the inner tube 11a and the outer tube 11b through the outside air introduction hole 30b with the shutter 30c opened. On the other hand, the stop of the outside air supply device 30 means that the shutter 30c is closed and the outside air OA is not supplied between the inner tube 11a and the outer tube 11b from the outside air introduction hole 30b.

この判定温度閾値Ｔ１は、選択還元型触媒装置１３に流入する排気ガスＧの温度Ｔがこの判定温度閾値Ｔ１より高温になると、選択還元型触媒装置１３内部のアンモニア吸着量が大幅に低減されて、大量のアンモニアが選択還元型触媒装置１３より大気に排出される（アンモニアスリップ）懸念があるものとして、予め実験等により設定される温度閾値であり、例えば、３５０℃〜４５０℃に設定される。従来技術では、排気ガスＧの温度Ｔが判定温度閾値Ｔ１より高温になると、アンモニアスリップを抑制すべく、選択還元型触媒装置１３の入口に配設した尿素水供給装置１２からの尿素水Ｕの噴射量を制限したり、または、尿素水Ｕの噴射を停止したりする措置をとっていた。   The determination temperature threshold T1 is such that when the temperature T of the exhaust gas G flowing into the selective reduction catalyst device 13 becomes higher than the determination temperature threshold T1, the ammonia adsorption amount inside the selective reduction catalyst device 13 is greatly reduced. A temperature threshold that is set in advance through experiments or the like, for example, is set to 350 ° C. to 450 ° C., assuming that a large amount of ammonia may be discharged from the selective reduction catalyst device 13 into the atmosphere (ammonia slip). . In the prior art, when the temperature T of the exhaust gas G becomes higher than the determination temperature threshold value T1, the urea water U from the urea water supply device 12 disposed at the inlet of the selective catalytic reduction catalyst device 13 is suppressed to suppress ammonia slip. Measures were taken to limit the injection amount or to stop the injection of urea water U.

これに対し、本発明では、選択還元型触媒装置１３に流入する排気ガスＧの温度Ｔが判定温度閾値Ｔ１以上のときに、排気ガスＧの温度Ｔが判定温度閾値Ｔ１未満になるように、外気供給装置３０を作動させ、選択還元型触媒装置１３に流入する排気ガスＧを外気ＯＡで冷却することで、選択還元型触媒装置１３の温度の上昇を抑制することができるので、選択還元型触媒装置１３内部のアンモニア吸着量の低減を抑制することができる。   In contrast, in the present invention, when the temperature T of the exhaust gas G flowing into the selective catalytic reduction device 13 is equal to or higher than the determination temperature threshold T1, the temperature T of the exhaust gas G is less than the determination temperature threshold T1. By operating the outside air supply device 30 and cooling the exhaust gas G flowing into the selective catalytic reduction device 13 with the outside air OA, the temperature increase of the selective catalytic reduction device 13 can be suppressed. Reduction of the ammonia adsorption amount inside the catalyst device 13 can be suppressed.

そして、上記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、内燃機関の排気通路１１に尿素水供給装置１２、選択還元型触媒装置１３を備えるとともに、排気通路１１を構成する排気管１１ａの周囲に外気ＯＡを供給して、選択還元型触媒装置１３に流入する排気ガスＧを冷却する外気供給装置３０を設け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に流入する排気ガスＧの温度Ｔが予め設定された判定温度閾値Ｔ１以上のときには、排気ガスＧの温度Ｔが判定温度閾値Ｔ１未満になるように、外気供給装置３０を作動させて、選択還元型触媒装置１３に流入する排気ガスＧを外気ＯＡで冷却し、排気ガスＧの温度Ｔが予め設定された判定温度閾値Ｔ１未満のときには、外気供給装置３０を停止させて、選択還元型触媒装置１３に流入する排気ガスＧを外気ＯＡで冷却しないようにすることを特徴とする方法である。   An exhaust gas purification method for an internal combustion engine according to the present invention based on the exhaust gas purification system 1 for the internal combustion engine includes a urea water supply device 12 and a selective reduction catalyst device 13 in an exhaust passage 11 of the internal combustion engine. At the same time, the exhaust gas of the internal combustion engine configured to supply the outside air OA around the exhaust pipe 11a constituting the exhaust passage 11 and cool the exhaust gas G flowing into the selective catalytic reduction catalyst device 13 is provided. In the gas purification method, when the temperature T of the exhaust gas G flowing into the selective catalytic reduction device 13 is equal to or higher than a preset judgment temperature threshold T1, the temperature T of the exhaust gas G is less than the judgment temperature threshold T1. When the outside air supply device 30 is operated and the exhaust gas G flowing into the selective catalytic reduction device 13 is cooled by the outside air OA, the temperature T of the exhaust gas G is less than a preset judgment temperature threshold T1. , The outside air supply device 30 is stopped, a method characterized by so as not to cool the exhaust gas G flowing into the selective reduction catalyst device 13 in the outside air OA.

より具体的には、外気供給装置３０を、排気管１１ａを内管として、選択還元型触媒装置１３が備えられる箇所周辺の内管１１ａの外部に、選択還元型触媒装置１３を保温する外管１１ｂ又はケースを設けて２重構造とした２重構造部３０ａと、内管１１ａと外管１１ｂ又はケースの間に外気ＯＡを導入するために、外管１１ｂ又はケースに設けた外気導入孔３０ｂと、この外気導入孔３０ｂからの外気ＯＡの導入の有無を切り替えるために、外気導入孔３０ｂに設けた開閉装置３０ｃとで構成するとともに、選択還元型触媒装置１３に流入する排気ガスＧの温度Ｔが判定温度閾値Ｔ１以上のときには、排気ガスＧの温度Ｔが判定温度閾値Ｔ１未満になるように、開閉装置３０ｃを開状態とし、選択還元型触媒装置１３に流入する排気ガスＧを外気で冷却し、選択還元型触媒装置１３に流入する排気ガスＧの温度Ｔが判定温度閾値Ｔ１未満のときには、開閉装置３０ｃを閉状態とし、選択還元型触媒装置１３に流入する排気ガスＧを外気ＯＡで冷却しないようにすることを特徴とする方法である。   More specifically, the outside air supply device 30 is an outer tube that keeps the selective catalytic reduction catalyst device 13 outside the inner pipe 11a around the location where the selective catalytic reduction catalyst device 13 is provided with the exhaust pipe 11a as an inner pipe. 11b or a double structure portion 30a having a double structure by providing a case, and an outside air introduction hole 30b provided in the outer tube 11b or the case in order to introduce the outside air OA between the inner tube 11a and the outer tube 11b or the case. And an opening / closing device 30c provided in the outside air introduction hole 30b in order to switch whether or not the outside air OA is introduced from the outside air introduction hole 30b, and the temperature of the exhaust gas G flowing into the selective catalytic reduction device 13 When T is equal to or higher than the determination temperature threshold T1, the opening / closing device 30c is opened so that the temperature T of the exhaust gas G is less than the determination temperature threshold T1, and the exhaust gas G flowing into the selective catalytic reduction catalyst device 13 is opened. When the temperature T of the exhaust gas G that cools with outside air and flows into the selective catalytic reduction device 13 is less than the determination temperature threshold T1, the opening / closing device 30c is closed, and the exhaust gas G flowing into the selective catalytic reduction device 13 is discharged. It is a method characterized by not cooling with outside air OA.

そして、上記の構成の内燃機関の排気ガス浄化システム１、内燃機関、及び内燃機関の排気ガス浄化方法によれば、アンモニアスリップの懸念があるようなエンジンの運転条件でも、選択還元型触媒装置１３の温度制御を外気ＯＡを用いて行うことで、アンモニアスリップを抑制することができるとともに、大気へのＮＯｘの排出量の増加を抑制することができ、高効率かつ継続的なＮＯｘ浄化を行うことができる。   According to the exhaust gas purification system 1 for an internal combustion engine, the internal combustion engine, and the exhaust gas purification method for the internal combustion engine configured as described above, the selective catalytic reduction device 13 can be used even under engine operating conditions that may cause ammonia slip. By controlling the temperature of the atmosphere using the outside air OA, ammonia slip can be suppressed, and increase in the amount of NOx discharged to the atmosphere can be suppressed, and highly efficient and continuous NOx purification is performed. Can do.

特に、外気供給装置３０を２重構造部３０ａ、外気導入孔３０ｂ及び開閉装置３０ｃで構成することで、選択還元型触媒装置１３の温度Ｔが判定温度閾値Ｔ１未満であるときには、２重構造部３０ａにより選択還元型触媒装置１３の保温性能を向上させることで、選択還元型触媒装置１３に担持した触媒の温度を活性化温度範囲内に維持することができるとともに、選択還元型触媒装置１３の温度Ｔが判定温度閾値Ｔ１以上であるときには、選択還元型触媒装置１３に流入する排気ガスＧを外気ＯＡで確実に冷却することで、上記の作用効果（アンモニアスリップの抑制、高効率かつ継続的なＮＯｘ浄化）を確実に奏することができる。   In particular, when the outside air supply device 30 includes the double structure portion 30a, the outside air introduction hole 30b, and the opening / closing device 30c, when the temperature T of the selective catalytic reduction catalyst device 13 is less than the determination temperature threshold value T1, the double structure portion. By improving the heat retention performance of the selective catalytic reduction device 13 by 30a, the temperature of the catalyst supported on the selective catalytic reduction device 13 can be maintained within the activation temperature range, and When the temperature T is equal to or higher than the determination temperature threshold value T1, the exhaust gas G flowing into the selective catalytic reduction catalyst device 13 is reliably cooled by the outside air OA, so that the above-described effect (suppression of ammonia slip, high efficiency and continuous Reliable NOx purification).

１ 内燃機関の排気ガス浄化システム
１１ 排気通路
１１ａ 排気管（内管）
１１ｂ 外管
１２ 尿素水供給装置
１３ 選択還元型触媒装置（ＳＣＲ）
１４ アンモニアスリップ触媒装置（ＡＳＣ）
２０ 排気温度センサ（排気温度検出装置）
３０ 外気供給装置
３０ａ ２重構造部
３０ｂ 外気導入孔
３０ｃ シャッター（開閉装置）
４０ 制御装置
Ｕ 尿素水
Ｇ 選択還元型触媒装置に流入する排気ガス
Ｇｃ 浄化処理された排気ガス DESCRIPTION OF SYMBOLS 1 Exhaust gas purification system 11 of internal combustion engine Exhaust passage 11a Exhaust pipe (inner pipe)
11b Outer pipe 12 Urea water supply device 13 Selective reduction type catalyst device (SCR)
14 Ammonia slip catalyst device (ASC)
20 Exhaust temperature sensor (exhaust temperature detector)
30 Outside air supply device 30a Double structure portion 30b Outside air introduction hole 30c Shutter (opening / closing device)
40 Control device U Urea water G Exhaust gas Gc flowing into the selective catalytic reduction catalyst device Exhaust gas subjected to purification treatment

Claims (5)

内燃機関の排気通路に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、
前記選択還元型触媒装置より上流側の前記排気通路に、前記選択還元型触媒装置に流入する排気ガスの温度を検出する排気温度検出装置を設けるとともに、
前記排気通路を構成する排気管の周囲に外気を供給して前記選択還元型触媒装置に流入する排気ガスを冷却する外気供給装置を設け、
当該排気ガス浄化システムを制御する制御装置が、
前記排気温度検出装置の検出値が予め設定された判定温度閾値以上のときには、排気ガスの温度が前記判定温度閾値未満になるように、前記外気供給装置を作動させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却し、
前記排気温度検出装置の検出値が前記判定温度閾値未満のときには、前記外気供給装置を停止させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却しない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 purification system of an internal combustion engine configured to include a selective reduction catalyst device in an exhaust passage of the internal combustion engine,
An exhaust temperature detection device for detecting the temperature of the exhaust gas flowing into the selective reduction catalyst device is provided in the exhaust passage upstream of the selective reduction catalyst device,
Providing an outside air supply device for supplying outside air around the exhaust pipe constituting the exhaust passage to cool the exhaust gas flowing into the selective reduction catalyst device;
A control device for controlling the exhaust gas purification system,
When the detected value of the exhaust temperature detection device is equal to or higher than a preset determination temperature threshold, the outside air supply device is operated so that the temperature of the exhaust gas becomes lower than the determination temperature threshold, and the selective reduction catalyst device Cool the exhaust gas flowing into the outside air,
When the detected value of the exhaust temperature detection device is less than the determination temperature threshold, the external air supply device is stopped, and the internal combustion engine configured so as not to cool the exhaust gas flowing into the selective reduction catalyst device with external air Exhaust gas purification system. 前記外気供給装置を、
前記排気管を内管として、前記選択還元型触媒装置が備えられる箇所周辺の前記内管の外部に、前記選択還元型触媒装置を保温する外管又はケースを設けて２重構造とした２重構造部と、
前記内管と前記外管又はケースの間に外気を導入するために、前記外管又はケースに設けた外気導入孔と、
該外気導入孔からの外気の導入の有無を切り替えるために、前記外気導入孔に設けた開閉装置とで構成される請求項１に記載の内燃機関の排気ガス浄化システム。 The outside air supply device,
A double structure in which the exhaust pipe is an inner pipe, and an outer pipe or a case for keeping the selective reduction catalyst apparatus is provided outside the inner pipe around the place where the selective reduction catalyst apparatus is provided. A structure part;
In order to introduce outside air between the inner tube and the outer tube or the case, an outside air introduction hole provided in the outer tube or the case,
The exhaust gas purification system for an internal combustion engine according to claim 1, comprising an opening / closing device provided in the outside air introduction hole for switching whether or not outside air is introduced from the outside air introduction hole. 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を備えて構成される内燃機関。   An internal combustion engine comprising the exhaust gas purification system for an internal combustion engine according to claim 1 or 2. 内燃機関の排気通路に選択還元型触媒装置を備えるとともに、前記排気通路を構成する排気管の周囲に外気を供給して前記選択還元型触媒装置に流入する排気ガスを冷却する外気供給装置を設け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に流入する排気ガスの温度が予め設定された判定温度閾値以上のときには、排気ガスの温度が前記判定温度閾値未満になるように、前記外気供給装置を作動させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却し、
前記選択還元型触媒装置に流入する排気ガスの温度が前記判定温度閾値未満のときには、前記外気供給装置を停止させて、前記選択還元型触媒装置に流入する排気ガスを外気で冷却しないようにすることを特徴とする内燃機関の排気ガス浄化方法。 A selective reduction catalyst device is provided in the exhaust passage of the internal combustion engine, and an outside air supply device is provided for cooling the exhaust gas flowing into the selective reduction catalyst device by supplying outside air around the exhaust pipe constituting the exhaust passage. In the exhaust gas purification method for an internal combustion engine configured as follows:
When the temperature of the exhaust gas flowing into the selective catalytic reduction catalyst device is equal to or higher than a predetermined determination temperature threshold, the outside air supply device is operated so that the temperature of the exhaust gas is lower than the determination temperature threshold, The exhaust gas flowing into the selective catalytic reduction device is cooled with outside air,
When the temperature of the exhaust gas flowing into the selective reduction catalyst device is less than the determination temperature threshold, the outside air supply device is stopped so that the exhaust gas flowing into the selective reduction catalyst device is not cooled by outside air. An exhaust gas purification method for an internal combustion engine. 前記外気供給装置を、
前記排気管を内管として、前記選択還元型触媒装置が備えられる箇所周辺の前記内管の外部に、前記選択還元型触媒装置を保温する外管又はケースを設けて２重構造とした２重構造部と、
前記内管と前記外管又はケースの間に外気を導入するために、前記外管又はケースに設けた外気導入孔と、
該外気導入孔からの外気の導入の有無を切り替えるために、前記外気導入孔に設けた開閉装置とで構成するとともに、
前記選択還元型触媒装置に流入する排気ガスの温度が前記判定温度閾値以上のときには、排気ガスの温度が前記判定温度閾値未満になるように、前記開閉装置を開状態とし、前記選択還元型触媒装置に流入する排気ガスを外気で冷却し、
前記選択還元型触媒装置に流入する排気ガスの温度が前記判定温度閾値未満のときには、前記開閉装置を閉状態とし、前記選択還元型触媒装置に流入する排気ガスを外気で冷却しないようにすることを特徴とする請求項４に記載の内燃機関の排気ガス浄化方法。 The outside air supply device,
A double structure in which the exhaust pipe is an inner pipe, and an outer pipe or a case for keeping the selective reduction catalyst apparatus is provided outside the inner pipe around the place where the selective reduction catalyst apparatus is provided. A structure part;
In order to introduce outside air between the inner tube and the outer tube or the case, an outside air introduction hole provided in the outer tube or the case,
In order to switch the presence or absence of the introduction of outside air from the outside air introduction hole, and configured with an opening and closing device provided in the outside air introduction hole,
When the temperature of the exhaust gas flowing into the selective reduction catalyst device is equal to or higher than the determination temperature threshold, the open / close device is opened so that the temperature of the exhaust gas is lower than the determination temperature threshold, and the selective reduction catalyst Cool the exhaust gas flowing into the device with outside air,
When the temperature of the exhaust gas flowing into the selective catalytic reduction device is lower than the determination temperature threshold, the opening / closing device is closed so that the exhaust gas flowing into the selective catalytic reduction device is not cooled by outside air. The exhaust gas purification method for an internal combustion engine according to claim 4.
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Cited By (1)

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CN109915237A (en) * 2017-12-12 2019-06-21 通用汽车环球科技运作有限责任公司 The method of control selections catalyst reduction system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109915237A (en) * 2017-12-12 2019-06-21 通用汽车环球科技运作有限责任公司 The method of control selections catalyst reduction system
CN109915237B (en) * 2017-12-12 2021-04-02 通用汽车环球科技运作有限责任公司 Method for controlling selective catalytic reduction system

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