JP3687914B2 - Engine exhaust purification system - Google Patents

Engine exhaust purification system Download PDF

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JP3687914B2
JP3687914B2 JP2003327591A JP2003327591A JP3687914B2 JP 3687914 B2 JP3687914 B2 JP 3687914B2 JP 2003327591 A JP2003327591 A JP 2003327591A JP 2003327591 A JP2003327591 A JP 2003327591A JP 3687914 B2 JP3687914 B2 JP 3687914B2
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temperature
reducing agent
tank
engine
heat medium
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JP2005090431A (en
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公信 平田
久 赤川
秀一 中村
弘樹 上野
伊久雄 酒井
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UD Trucks Corp
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UD Trucks Corp
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Priority to JP2003327591A priority Critical patent/JP3687914B2/en
Priority to US10/572,558 priority patent/US7849674B2/en
Priority to EP11191519.5A priority patent/EP2426328B1/en
Priority to PCT/JP2004/012743 priority patent/WO2005028826A1/en
Priority to EP04787623A priority patent/EP1669567B1/en
Priority to EP11191521.1A priority patent/EP2426329B1/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/10Adding substances to exhaust gases the substance being heated, e.g. by heating tank or supply line of the added substance
    • F01N2610/105Control thereof
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/14Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1406Storage means for substances, e.g. tanks or reservoirs

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  • Exhaust Gas After Treatment (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Description

本発明は、エンジンから排出される排気中の窒素酸化物(NOx)を、還元剤を用いて還元浄化する排気浄化装置に関し、特に還元剤を貯蔵するタンクの開閉時に発生する悪臭を抑制させる技術に関する。   The present invention relates to an exhaust purification device that reduces and purifies nitrogen oxides (NOx) in exhaust exhausted from an engine by using a reducing agent, and in particular, a technique for suppressing bad odors that occur when a tank that stores the reducing agent is opened and closed. About.

エンジンから排出される排気中のNOxを浄化する排気浄化装置として、特開2000−27627号公報(特許文献1)に開示されるような排気浄化装置が提案されている。
かかる排気浄化装置は、エンジンの排気通路にNOx還元触媒を介装し、NOx還元触媒の上流側に還元剤を噴射供給することにより、排気中のNOxと還元剤とを触媒還元反応させ、NOxを無害成分に浄化処理するものである。還元剤は常温において液体状態でタンクに貯蔵され、エンジン運転状態に対応した必要量が噴射ノズルから噴射供給される。還元反応は、NOxと反応性のよいアンモニアを用いるもので、還元剤としては、加水分解してアンモニアを容易に発生する尿素水が用いられる。そして、タンクに貯蔵した尿素水が、寒冷期に凍結しないように、タンク内に電熱線が設けられている。ところが、尿素水が必要以上に高温となってしまうと、タンク内においてアンモニア系ガスが発生してしまう。そこで、これを抑制するために、タンク内の尿素水の温度を検出して、所定温度以上となったときにその加熱を停止している。
特開2000−27627号公報
As an exhaust gas purification device that purifies NOx in exhaust gas discharged from an engine, an exhaust gas purification device as disclosed in Japanese Patent Laid-Open No. 2000-27627 (Patent Document 1) has been proposed.
Such an exhaust purification device includes a NOx reduction catalyst in an engine exhaust passage and injects and supplies a reducing agent to the upstream side of the NOx reduction catalyst, thereby causing a catalytic reduction reaction between NOx and the reducing agent in the exhaust gas. Is purified to harmless components. The reducing agent is stored in a tank in a liquid state at room temperature, and a necessary amount corresponding to the engine operating state is supplied by injection from an injection nozzle. The reduction reaction uses ammonia that is highly reactive with NOx, and as the reducing agent, urea water that is easily hydrolyzed to generate ammonia is used. And the heating wire is provided in the tank so that the urea water stored in the tank may not freeze in the cold season. However, if the urea water becomes hotter than necessary, ammonia-based gas is generated in the tank. Therefore, in order to suppress this, the temperature of the urea water in the tank is detected, and the heating is stopped when the temperature exceeds a predetermined temperature.
JP 2000-27627 A

しかしながら、このようなエンジンの排気浄化装置では、タンクに貯蔵した尿素水を加熱するために、電熱線において電力が消費されてしまう。このため、電熱線の駆動源であるバッテリの容量を増加させる必要があり、コストの上昇や、バッテリの設置スペースの増大を招いてしまう。このため、電熱線の代わりに、エンジンにより加熱された冷却水をタンク内に循環させることによって、廃熱を利用して尿素水を加熱することが考えられる。   However, in such an exhaust purification device for an engine, power is consumed in the heating wire in order to heat the urea water stored in the tank. For this reason, it is necessary to increase the capacity of the battery, which is the driving source of the heating wire, leading to an increase in cost and an increase in the installation space of the battery. For this reason, it is conceivable to heat the urea water using waste heat by circulating the cooling water heated by the engine in the tank instead of the heating wire.

ところが、このようなエンジンの排気浄化装置では、高温の尿素水がタンク内を循環すると、その周囲の尿素水が局所的に加熱されて、アンモニア系ガスが発生してタンクの上部空間に溜まってしまう。そして、例えば、タンク内へ尿素水を補給するときに、作業者がタンクの注入口を開けると、注入口からこのアンモニア系ガスが放出され、悪臭が発生してしまう恐れがあった。また、この悪臭は、尿素水だけでなく、アンモニア水溶液や、炭化水素を主成分とした軽油等であっても、同様に発生してしまう。   However, in such an exhaust purification device for an engine, when high-temperature urea water circulates in the tank, the surrounding urea water is locally heated and ammonia-based gas is generated and collected in the upper space of the tank. End up. For example, when the worker opens the tank inlet when supplying the urea water into the tank, the ammonia-based gas may be released from the inlet and a bad odor may be generated. Further, this malodor is generated not only in urea water but also in an aqueous ammonia solution or light oil mainly composed of hydrocarbons.

そこで、本発明は、以上のような従来の問題点に鑑み、エンジンにより加熱された冷却水が所定温度より高いときにタンク内を循環しないようにして、タンク開閉時に発生する悪臭を抑制させるエンジンの排気浄化装置を提供することを目的とする。   Therefore, in view of the conventional problems as described above, the present invention prevents the bad odor generated when the tank is opened and closed by preventing the cooling water heated by the engine from circulating in the tank when the temperature is higher than a predetermined temperature. An object of the present invention is to provide an exhaust purification device.

請求項1に記載の発明では、エンジン排気通路に配設され、窒素酸化物を還元剤により還元浄化する還元触媒と、前記還元剤を貯蔵するタンクと、前記タンクに貯蔵された還元剤を前記還元触媒に供給する還元剤供給装置と、エンジンにより加熱された熱媒体を前記タンク内に循環させることにより、前記タンクに貯蔵された還元剤を加熱する加熱装置と、前記熱媒体を前記タンク内に導く通路を遮断する遮断装置と、前記熱媒体の温度を検出する熱媒体温度検出装置と、前記熱媒体温度検出装置により検出された熱媒体の温度が第1の所定温度より高いときに、前記通路を遮断するように前記遮断装置を制御する第1の制御手段と、を含んで、エンジンの排気浄化装置が構成されることを特徴とする。   In the first aspect of the present invention, the reduction catalyst disposed in the engine exhaust passage for reducing and purifying nitrogen oxides with a reducing agent, the tank for storing the reducing agent, and the reducing agent stored in the tank are A reducing agent supply device for supplying the reducing catalyst; a heating device for heating the reducing agent stored in the tank by circulating a heating medium heated by the engine in the tank; and the heating medium in the tank. When the temperature of the heat medium detected by the heat medium temperature detecting device, the heat medium temperature detecting device for detecting the temperature of the heat medium, and the heat medium temperature detecting device is higher than the first predetermined temperature, And an engine exhaust purification device including a first control means for controlling the shut-off device so as to shut off the passage.

請求項2に記載の発明では、前記タンクに貯蔵された還元剤の温度を検出する還元剤温度検出装置と、前記還元剤温度検出装置により検出された還元剤の温度が第2の所定温度以上であるときに、前記通路を遮断するように前記遮断装置を制御する第2の制御手段と、を備えたことを特徴とする。
請求項3に記載の発明では、前記エンジンの始動直後であって、前記熱媒体温度検出装置により検出された熱媒体の温度が前記還元剤の凍結温度より高いときに、前記通路の遮断を強制的に所定時間解除させるように前記遮断装置を制御する第3の制御手段を備えたことを特徴とする。
In the invention according to claim 2, the reducing agent temperature detecting device for detecting the temperature of the reducing agent stored in the tank, and the temperature of the reducing agent detected by the reducing agent temperature detecting device is not less than a second predetermined temperature. And a second control means for controlling the blocking device so as to block the passage.
According to a third aspect of the present invention, immediately after the engine is started, the passage of the passage is forcibly forced when the temperature of the heat medium detected by the heat medium temperature detection device is higher than the freezing temperature of the reducing agent. And third control means for controlling the shut-off device so as to be released for a predetermined time.

請求項4に記載の発明では、前記遮断装置は、手動にて前記通路の遮断を解除できることを特徴とする。   The invention according to claim 4 is characterized in that the blocking device can manually release the blocking of the passage.

請求項1に記載の発明によれば、エンジンの排気中の窒素酸化物は、還元剤供給装置によりタンクから供給された還元剤を用いて、還元触媒において還元浄化される。また、エンジンにより加熱された熱媒体が還元剤を貯蔵するタンク内を循環するので、タンク内の還元剤が加熱され、還元剤の凍結を防止できる。
このとき、タンク内を循環する熱媒体の温度が第1の所定温度より高いときに、熱媒体をタンク内に導く通路が遮断されるので、第1の所定温度より高い温度の熱媒体が、タンク内を循環することが防止される。そして、第1の所定温度を、還元剤から気体が発生する下限温度より若干低く設定することによって、タンク内での還元剤からの気体の発生を抑制することができ、作業者がタンクの注入口を開けても、注入口から気体が放出されることが抑制され、悪臭の発生を抑制させることができる。
According to the first aspect of the present invention, nitrogen oxide in the exhaust of the engine is reduced and purified by the reduction catalyst using the reducing agent supplied from the tank by the reducing agent supply device. Moreover, since the heat medium heated by the engine circulates in the tank that stores the reducing agent, the reducing agent in the tank is heated, and freezing of the reducing agent can be prevented.
At this time, when the temperature of the heat medium circulating in the tank is higher than the first predetermined temperature, the passage for guiding the heat medium into the tank is blocked, so that the heat medium having a temperature higher than the first predetermined temperature is Circulation in the tank is prevented. Then, by setting the first predetermined temperature slightly lower than the lower limit temperature at which gas is generated from the reducing agent, generation of gas from the reducing agent in the tank can be suppressed, and the operator can inject the tank. Even if the inlet is opened, the release of gas from the inlet is suppressed, and the generation of malodor can be suppressed.

請求項2に記載の発明によれば、タンクに貯蔵された還元剤の温度が第2の所定温度以上であるときに、熱媒体をタンク内に導く通路が遮断されるので、タンク内の還元剤の温度が第2の所定温度未満に保たれる。そして、第2の所定温度を第1の所定温度と同様に、還元剤から気体が発生する下限温度より若干低く設定することによって、タンク内での還元剤からの気体の発生を更に抑制することができる。   According to the second aspect of the present invention, when the temperature of the reducing agent stored in the tank is equal to or higher than the second predetermined temperature, the passage for guiding the heat medium into the tank is blocked. The temperature of the agent is kept below the second predetermined temperature. Then, similarly to the first predetermined temperature, the generation of gas from the reducing agent in the tank is further suppressed by setting the second predetermined temperature slightly lower than the lower limit temperature at which gas is generated from the reducing agent. Can do.

請求項3に記載の発明によれば、熱媒体の温度が還元剤の凍結温度より高いときには、エンジンの始動直後から所定時間は熱媒体がタンク内を循環する。これにより、タンク内に低温の熱媒体が循環することによって還元剤が冷却されて凍結することを防止しつつ、通路内に熱媒体が残留することを防止でき、熱媒体の品質の低下を抑制することができる。   According to the invention described in claim 3, when the temperature of the heat medium is higher than the freezing temperature of the reducing agent, the heat medium circulates in the tank for a predetermined time immediately after the engine is started. This prevents the reductant from being cooled and frozen by circulating a low-temperature heat medium in the tank, while preventing the heat medium from remaining in the passage and suppressing deterioration in the quality of the heat medium. can do.

請求項4に記載の発明によれば、手動にて熱媒体の通路の遮断を解除できるので、熱媒体を交換するときに、熱媒体の通路内に残留する熱媒体も排出させて、その全量を交換することができる。   According to the invention described in claim 4, since the interruption of the passage of the heat medium can be manually released, when replacing the heat medium, the heat medium remaining in the passage of the heat medium is also discharged, and the total amount thereof Can be exchanged.

図1に本発明のエンジンの排気浄化装置の構成を示す。
エンジン1の排気通路である排気管2には、NOxを還元浄化するNOx還元触媒3が介装されている。また、NOx還元触媒3の上流には、排気管2内に開口した噴孔から還元剤を噴射供給する噴射ノズル4が設けられている。
エアリザーバタンク5に貯留された圧縮空気は、電磁開閉弁6を通過して、還元剤供給装置7に供給される。
FIG. 1 shows the configuration of an exhaust emission control device for an engine according to the present invention.
An NOx reduction catalyst 3 for reducing and purifying NOx is interposed in an exhaust pipe 2 that is an exhaust passage of the engine 1. Further, upstream of the NOx reduction catalyst 3, an injection nozzle 4 that supplies a reducing agent from an injection hole opened in the exhaust pipe 2 is provided.
The compressed air stored in the air reservoir tank 5 passes through the electromagnetic on-off valve 6 and is supplied to the reducing agent supply device 7.

タンク10に貯蔵された還元剤としての尿素水は、供給配管11を介して還元剤供給装置7に供給される。なお、還元剤は、尿素水の他にアンモニア水溶液、或いは、炭化水素を主成分とする軽油等でもよい。また、タンク10内には、タンク10に貯蔵されている尿素水の温度を検出する還元剤温度センサ12(還元剤温度検出装置)が設けられている。   The urea water as the reducing agent stored in the tank 10 is supplied to the reducing agent supply device 7 via the supply pipe 11. Note that the reducing agent may be an aqueous ammonia solution, urea oil or light oil containing hydrocarbon as a main component in addition to urea water. Further, a reducing agent temperature sensor 12 (reducing agent temperature detecting device) for detecting the temperature of the urea water stored in the tank 10 is provided in the tank 10.

還元剤供給装置7は、内部にポンプを有しており、ポンプが作動することによりエアリザーバタンク5から供給された圧縮空気に尿素水を添加し、尿素水を噴霧状態にして噴射ノズル4に供給する。なお、尿素水の添加流量は、ポンプの作動を制御することにより可変になっている。そして、還元剤供給装置7にて排気管2内に供給されなかった余剰の尿素水は戻り配管13を介してタンク10内に戻される。   The reducing agent supply device 7 has a pump inside, and by operating the pump, urea water is added to the compressed air supplied from the air reservoir tank 5, and the urea water is sprayed to the injection nozzle 4. Supply. The urea water addition flow rate is variable by controlling the operation of the pump. Then, excess urea water that has not been supplied into the exhaust pipe 2 by the reducing agent supply device 7 is returned into the tank 10 via the return pipe 13.

一方、エンジン1の図示しない冷却水の循環通路に並列して設けられた冷却水循環通路20には、電磁開閉弁22(遮断装置)、タンク10内の尿素水と熱交換する熱交換パイプ23を備えた熱交換装置24(加熱装置)が上流より順番に介装されている。電磁開閉弁22は、開閉作動することによって、冷却水循環通路20を開通或いは遮断させる。そして、熱交換装置24は、電磁開閉弁22が開いたときに、エンジン1により加熱され熱媒体として作用する冷却水が冷却水循環通路20を循環することにより、熱交換パイプ23を介して冷却水と尿素水とを熱交換させて、タンク10内の尿素水を加熱する。   On the other hand, a cooling water circulation passage 20 provided in parallel with a cooling water circulation passage (not shown) of the engine 1 is provided with an electromagnetic on-off valve 22 (blocking device) and a heat exchange pipe 23 for exchanging heat with urea water in the tank 10. The provided heat exchange device 24 (heating device) is interposed in order from the upstream. The electromagnetic on-off valve 22 opens or closes the cooling water circulation passage 20 by opening and closing. Then, when the electromagnetic on-off valve 22 is opened, the heat exchanging device 24 circulates the cooling water heated by the engine 1 and acting as a heat medium through the cooling water circulation passage 20, so that the cooling water passes through the heat exchanging pipe 23. The urea water in the tank 10 is heated by exchanging heat with the urea water.

エンジン1には、冷却水の温度を検出する冷却水温度センサ29(熱媒体温度検出装置)、エンジン1の回転速度や負荷等のエンジン運転状態を検出する運転状態検出センサ30が設けられている。マイクロコンピュータを内蔵したコントローラ31は、運転状態検出センサ30からエンジン運転状態を入力して、還元剤供給装置7のポンプ、電磁開閉弁6を作動制御することにより、エンジンの運転状態に見合った最適な量の尿素水を噴射ノズル4から排気管2内に噴射供給させる。   The engine 1 is provided with a cooling water temperature sensor 29 (heat medium temperature detection device) that detects the temperature of the cooling water, and an operation state detection sensor 30 that detects an engine operation state such as the rotation speed and load of the engine 1. . The controller 31 with a built-in microcomputer inputs the engine operating state from the operating state detection sensor 30 and controls the operation of the pump and the electromagnetic on-off valve 6 of the reducing agent supply device 7 so that it is optimal for the engine operating state. An appropriate amount of urea water is injected and supplied from the injection nozzle 4 into the exhaust pipe 2.

また、コントローラ31は、還元剤温度センサ12及び冷却水温度センサ29から、タンク10内の尿素水、冷却水の温度を入力し、電磁開閉弁22を作動制御する。
ここで、図2を用いて、コントローラ31での電磁開閉弁22の制御手順を説明する。まず、コントローラ31は、キースイッチ等の電源スイッチONにて電源が供給され、制御を開始する。なお、図示するフローチャートによる制御は所定時間毎に繰り返して行われる。
Further, the controller 31 inputs the temperature of the urea water and the cooling water in the tank 10 from the reducing agent temperature sensor 12 and the cooling water temperature sensor 29, and controls the operation of the electromagnetic on-off valve 22.
Here, the control procedure of the electromagnetic on-off valve 22 in the controller 31 will be described with reference to FIG. First, the controller 31 is supplied with power by turning on a power switch such as a key switch and starts control. The control according to the flowchart shown in the figure is repeatedly performed at predetermined time intervals.

始めにステップ1(図ではS1と表記する、以下同様)では、電磁開閉弁22を閉じるように制御する。
ステップ2では、還元剤温度センサ12からタンク10内の尿素水の温度を入力する。
ステップ3では、ステップ2にて入力した尿素水の温度が、所定温度Ta以下であるか否かを判定する。尿素水の温度が所定温度Ta以下であるときには、ステップ4へ進む(YES)。尿素水の温度が所定温度Ta以下でないときには、ステップ1へ戻る(NO)。なお、所定温度Taは、尿素水の凍結温度より若干高く設定すればよい。
First, in step 1 (denoted as S1 in the figure, the same applies hereinafter), the electromagnetic on-off valve 22 is controlled to be closed.
In step 2, the temperature of the urea water in the tank 10 is input from the reducing agent temperature sensor 12.
In step 3, it is determined whether the temperature of the urea water input in step 2 is equal to or lower than a predetermined temperature Ta. When the temperature of the urea water is equal to or lower than the predetermined temperature Ta, the process proceeds to step 4 (YES). When the temperature of the urea water is not lower than the predetermined temperature Ta, the process returns to step 1 (NO). The predetermined temperature Ta may be set slightly higher than the freezing temperature of the urea water.

ステップ4では、冷却水温度センサ29から冷却水の温度を入力する。
ステップ5では、ステップ4にて入力した冷却水の温度が所定温度Tb(第1の所定温度)以下であるか否かを判定する。冷却水の温度が所定温度Tb以下であるときには、ステップ6へ進む(YES)。冷却水の温度が所定温度Tb以下でないときには、ステップ1へ戻る(NO)。なお、所定温度Tbは、尿素水からアンモニアが発生する下限温度より若干低く設定すればよく、例えば、35重量パーセント濃度の尿素水の場合には80℃より若干低く設定すればよい。
In step 4, the coolant temperature is input from the coolant temperature sensor 29.
In step 5, it is determined whether or not the temperature of the cooling water input in step 4 is equal to or lower than a predetermined temperature Tb (first predetermined temperature). When the temperature of the cooling water is equal to or lower than the predetermined temperature Tb, the process proceeds to step 6 (YES). When the temperature of the cooling water is not lower than the predetermined temperature Tb, the process returns to step 1 (NO). The predetermined temperature Tb may be set slightly lower than the lower limit temperature at which ammonia is generated from the urea water. For example, in the case of 35 weight percent concentration urea water, it may be set slightly lower than 80 ° C.

ステップ6では、電磁開閉弁22を開くように制御する。
ステップ7では、還元剤温度センサ12からタンク10内の尿素水の温度を入力する。 ステップ8では、ステップ7にて入力した尿素水の温度が所定温度Tc(第2の所定温度)以上であるか否かを判定する。尿素水の温度が所定温度Tc以上であるときには、ステップ9へ進む(YES)。尿素水の温度が所定温度Tc以上でないときには、ステップ4へ戻る(NO)。なお、所定温度Tcを所定温度Taより若干高めに設定することで、タンク10内の尿素水の温度を所定温度Ta〜Tcの間に制御することができる。
In step 6, control is performed so that the electromagnetic on-off valve 22 is opened.
In step 7, the temperature of the urea water in the tank 10 is input from the reducing agent temperature sensor 12. In step 8, it is determined whether the temperature of the urea water input in step 7 is equal to or higher than a predetermined temperature Tc (second predetermined temperature). When the temperature of the urea water is equal to or higher than the predetermined temperature Tc, the process proceeds to step 9 (YES). When the temperature of the urea water is not equal to or higher than the predetermined temperature Tc, the process returns to step 4 (NO). Note that the temperature of the urea water in the tank 10 can be controlled between the predetermined temperatures Ta to Tc by setting the predetermined temperature Tc slightly higher than the predetermined temperature Ta.

ステップ9では、電磁開閉弁22を閉じるように制御し、その後ENDに進む。
なお、ステップ1、4及び5の一連の制御は第1の制御手段に該当し、ステップ7〜9の一連の制御は第2の制御手段に該当する。
次に、以上のような構成の排気浄化装置の作用について説明する。
エンジン1の排気は、排気管2を通って、NOx還元触媒3へと導かれる。このとき、コントローラ31は、運転状態検出センサ30からエンジン1の回転速度や負荷等のエンジン運転状態を入力して、還元剤供給装置7のポンプ、電磁開閉弁6を作動制御することにより、エンジン運転状態に見合った最適な量の尿素水を噴射ノズル4から排気管2内に噴射供給させる。これにより、NOx還元触媒3にて排気中のNOxが効率よく還元除去される。
In step 9, control is performed so as to close the electromagnetic on-off valve 22, and then the process proceeds to END.
Note that a series of control in steps 1, 4 and 5 corresponds to the first control means, and a series of control in steps 7 to 9 corresponds to the second control means.
Next, the operation of the exhaust emission control device having the above configuration will be described.
Exhaust gas from the engine 1 is guided to the NOx reduction catalyst 3 through the exhaust pipe 2. At this time, the controller 31 inputs the engine operation state such as the rotation speed and load of the engine 1 from the operation state detection sensor 30, and controls the pump of the reducing agent supply device 7 and the electromagnetic on-off valve 6 to control the engine. An optimal amount of urea water suitable for the operating state is injected and supplied from the injection nozzle 4 into the exhaust pipe 2. Thereby, NOx in the exhaust is efficiently reduced and removed by the NOx reduction catalyst 3.

タンク10内の尿素水の温度が所定温度Ta以下、即ち尿素水が凍結する可能性があり、かつ、エンジン1の冷却水の温度が所定温度Tb以下、即ち冷却水が高温でないときには、電磁開閉弁22が開く。これにより、エンジン1により加熱された冷却水が冷却水循環通路20を循環するので、タンク10内の尿素水は、熱交換パイプ23を介して冷却水と熱交換して加熱される。このため、尿素水の凍結を防止できる。   When the temperature of the urea water in the tank 10 is equal to or lower than the predetermined temperature Ta, that is, the urea water may freeze, and the temperature of the cooling water of the engine 1 is equal to or lower than the predetermined temperature Tb, that is, the cooling water is not hot, electromagnetic switching The valve 22 opens. As a result, the cooling water heated by the engine 1 circulates in the cooling water circulation passage 20, so that the urea water in the tank 10 is heated by exchanging heat with the cooling water via the heat exchange pipe 23. For this reason, freezing of urea water can be prevented.

このとき、エンジン1の冷却水の温度が所定温度Tbより高い、即ち冷却水が高温であるときには、電磁開閉弁22が閉じるので、高温の冷却水がタンク10内を循環することが防止される。これにより、タンク10内で尿素水からアンモニアが発生することを抑制することができ、作業者がタンク10の注入口を開けても、注入口からアンモニアが放出されることが抑制され、悪臭の発生を抑制することができる。   At this time, when the temperature of the cooling water of the engine 1 is higher than the predetermined temperature Tb, that is, when the cooling water is at a high temperature, the electromagnetic on-off valve 22 is closed, so that the high-temperature cooling water is prevented from circulating in the tank 10. . Thereby, it is possible to suppress the generation of ammonia from the urea water in the tank 10, and even if the operator opens the injection port of the tank 10, it is possible to suppress the release of ammonia from the injection port. Occurrence can be suppressed.

また、タンク10内の尿素水の温度が所定温度Tc以上、即ちタンク10内の尿素水が高温であるときにも、電磁開閉弁22が閉じるので、タンク10内の尿素水は、アンモニアが発生しない温度に保たれる。これにより、タンク10内で尿素水からアンモニアが発生することを更に抑制することができる。
更に、コントローラ31は、エンジン1の始動直後に、冷却水の温度が尿素水の凍結温度より高いときには、電磁開閉弁22を強制的に所定時間開放させるように制御することが望ましい。この制御は、第3の制御手段に該当する。これにより、冷却水の温度が尿素水の凍結温度より高いときには、エンジン1の始動直後から所定時間は冷却水が冷却水循環通路20を循環するので、タンク10内に低温の冷却水が循環することによって尿素水が冷却されて凍結することを防止しつつ、冷却水循環通路20内に冷却水が残留することを防止でき、冷却水の品質の低下を抑制することができる。
Further, when the temperature of the urea water in the tank 10 is equal to or higher than the predetermined temperature Tc, that is, when the urea water in the tank 10 is at a high temperature, the electromagnetic on-off valve 22 is closed, so that the urea water in the tank 10 generates ammonia. Do not keep the temperature. Thereby, it is possible to further suppress the generation of ammonia from the urea water in the tank 10.
Furthermore, it is desirable that the controller 31 controls the electromagnetic on-off valve 22 to be forcibly opened for a predetermined time immediately after the engine 1 is started and when the temperature of the cooling water is higher than the freezing temperature of the urea water. This control corresponds to the third control means. Thereby, when the temperature of the cooling water is higher than the freezing temperature of the urea water, the cooling water circulates in the cooling water circulation passage 20 for a predetermined time immediately after the start of the engine 1, so that the low-temperature cooling water circulates in the tank 10. Therefore, it is possible to prevent the cooling water from being left in the cooling water circulation passage 20 while preventing the urea water from being cooled and frozen, and to suppress the deterioration of the cooling water quality.

その他、電磁開閉弁22を、手動にて開放させることができるようにすることが望ましい。このようにすれば、冷却水を交換するときに、冷却水循環通路20内に残留する冷却水を排出させて、その全量を交換することができる。   In addition, it is desirable that the electromagnetic on-off valve 22 can be opened manually. If it does in this way, when replacing | exchanging cooling water, the cooling water which remains in the cooling water circulation channel | path 20 can be discharged | emitted, and the whole quantity can be exchanged.

本発明の排気浄化装置の実施形態の構成図Configuration diagram of an embodiment of an exhaust emission control device of the present invention 同上における電磁開閉弁の制御手順を示すフローチャートThe flowchart which shows the control procedure of the electromagnetic on-off valve in the same as the above

符号の説明Explanation of symbols

1 エンジン
2 排気管
3 NOx還元触媒
7 還元剤供給装置
10 タンク
12 還元剤温度センサ
20 冷却水循環通路
22 電磁開閉弁
24 熱交換装置
29 冷却水温度センサ
31 コントローラ
DESCRIPTION OF SYMBOLS 1 Engine 2 Exhaust pipe 3 NOx reduction catalyst 7 Reducing agent supply apparatus 10 Tank 12 Reducing agent temperature sensor 20 Cooling water circulation passage 22 Electromagnetic on-off valve 24 Heat exchange device 29 Cooling water temperature sensor 31 Controller

Claims (4)

エンジン排気通路に配設され、窒素酸化物を還元剤により還元浄化する還元触媒と、
前記還元剤を貯蔵するタンクと、
前記タンクに貯蔵された還元剤を前記還元触媒に供給する還元剤供給装置と、
エンジンにより加熱された熱媒体を前記タンク内に循環させることにより、前記タンクに貯蔵された還元剤を加熱する加熱装置と、
前記熱媒体を前記タンク内に導く通路を遮断する遮断装置と、
前記熱媒体の温度を検出する熱媒体温度検出装置と、
前記熱媒体温度検出装置により検出された熱媒体の温度が第1の所定温度より高いときに、前記通路を遮断するように前記遮断装置を制御する第1の制御手段と、
を含んで構成されることを特徴とするエンジンの排気浄化装置。
A reduction catalyst disposed in the engine exhaust passage for reducing and purifying nitrogen oxides with a reducing agent;
A tank for storing the reducing agent;
A reducing agent supply device for supplying the reducing agent stored in the tank to the reduction catalyst;
A heating device that heats the reducing agent stored in the tank by circulating a heat medium heated by the engine in the tank;
A shut-off device that shuts off a passage that guides the heat medium into the tank;
A heat medium temperature detecting device for detecting the temperature of the heat medium;
First control means for controlling the blocking device to block the passage when the temperature of the heating medium detected by the heating medium temperature detection device is higher than a first predetermined temperature;
An exhaust emission control device for an engine characterized by comprising:
前記タンクに貯蔵された還元剤の温度を検出する還元剤温度検出装置と、
前記還元剤温度検出装置により検出された還元剤の温度が第2の所定温度以上であるときに、前記通路を遮断するように前記遮断装置を制御する第2の制御手段と、
を備えたことを特徴とする請求項1に記載のエンジンの排気浄化装置。
A reducing agent temperature detector for detecting the temperature of the reducing agent stored in the tank;
Second control means for controlling the blocking device to block the passage when the temperature of the reducing agent detected by the reducing agent temperature detection device is equal to or higher than a second predetermined temperature;
The exhaust emission control device for an engine according to claim 1, comprising:
前記エンジンの始動直後であって、前記熱媒体温度検出装置により検出された熱媒体の温度が前記還元剤の凍結温度より高いときに、前記通路の遮断を強制的に所定時間解除させるように前記遮断装置を制御する第3の制御手段を備えたことを特徴とする請求項1又は2に記載のエンジンの排気浄化装置。   Immediately after starting the engine, when the temperature of the heat medium detected by the heat medium temperature detecting device is higher than the freezing temperature of the reducing agent, the passage is forcibly released for a predetermined time. The engine exhaust gas purification apparatus according to claim 1 or 2, further comprising third control means for controlling the shut-off device. 前記遮断装置は、手動にて前記通路の遮断を解除できることを特徴とする請求項1〜3のいずれか1つに記載のエンジンの排気浄化装置。   The engine exhaust purification device according to any one of claims 1 to 3, wherein the shut-off device can manually release the shut-off of the passage.
JP2003327591A 2003-09-19 2003-09-19 Engine exhaust purification system Expired - Fee Related JP3687914B2 (en)

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JP2003327591A JP3687914B2 (en) 2003-09-19 2003-09-19 Engine exhaust purification system
US10/572,558 US7849674B2 (en) 2003-09-19 2004-09-02 Exhaust emission purifying apparatus for engine
EP11191519.5A EP2426328B1 (en) 2003-09-19 2004-09-02 Exhaust gas purification device of engine
PCT/JP2004/012743 WO2005028826A1 (en) 2003-09-19 2004-09-02 Exhaust gas purification device of engine
EP04787623A EP1669567B1 (en) 2003-09-19 2004-09-02 Exhaust gas purification device of engine
EP11191521.1A EP2426329B1 (en) 2003-09-19 2004-09-02 Exhaust gas purification device of engine

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