JP7203562B2 - Reducing agent supply device - Google Patents

Reducing agent supply device Download PDF

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JP7203562B2
JP7203562B2 JP2018201437A JP2018201437A JP7203562B2 JP 7203562 B2 JP7203562 B2 JP 7203562B2 JP 2018201437 A JP2018201437 A JP 2018201437A JP 2018201437 A JP2018201437 A JP 2018201437A JP 7203562 B2 JP7203562 B2 JP 7203562B2
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reducing agent
passage
agent supply
supply passage
displacement member
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敦史 徳永
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Robert Bosch GmbH
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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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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    • Y02T10/12—Improving ICE efficiencies

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Description

本発明は、内燃機関の排気通路に液体還元剤を供給するための還元剤供給装置に関する。 The present invention relates to a reducing agent supply device for supplying a liquid reducing agent to an exhaust passage of an internal combustion engine.

車両等に搭載された内燃機関から排出される排気ガスを浄化する排気浄化装置の一態様として、排気ガス中の窒素酸化物（ＮＯX）の還元反応を促進する選択還元触媒と、選択還元触媒よりも上流側で排気通路内に液体還元剤を供給する還元剤供給装置とを備えた排気浄化装置がある。還元剤供給装置として、タンク内の液体還元剤を吸い上げて圧送するポンプと、ポンプにより圧送される液体還元剤を排気通路内に噴射する還元剤噴射弁とを備えた装置が知られている。 As one aspect of an exhaust purification device for purifying exhaust gas emitted from an internal combustion engine mounted on a vehicle or the like, a selective reduction catalyst that promotes a reduction reaction of nitrogen oxides (NO x ) in the exhaust gas, and a selective reduction catalyst and a reducing agent supply device that supplies a liquid reducing agent into the exhaust passage on the upstream side of the exhaust purification device. As a reducing agent supply device, a device is known that includes a pump that sucks up a liquid reducing agent in a tank and pumps it, and a reducing agent injection valve that injects the liquid reducing agent pumped by the pump into an exhaust passage.

このような還元剤供給装置において、目標噴射量相当の液体還元剤を精度よく噴射するために、ポンプによって圧送される液体還元剤の一部を、還元剤供給通路から分岐するリターン通路を介してタンクに戻しながら還元剤供給通路内の圧力を一定に保ち、還元剤噴射弁の開閉を制御することが行われている。 In such a reducing agent supply device, in order to accurately inject the liquid reducing agent corresponding to the target injection amount, part of the liquid reducing agent pumped by the pump is passed through the return passage branching from the reducing agent supply passage. While the reducing agent is being returned to the tank, the pressure in the reducing agent supply passage is kept constant to control the opening and closing of the reducing agent injection valve.

ここで、内燃機関の停止後においても還元剤噴射弁や還元剤供給通路内に液体還元剤が残留していると、残留する尿素水溶液が凍結し、体積が膨張することによって還元剤噴射弁等が破損するおそれがある。このため、内燃機関の停止時には、還元剤供給装置内に残留する液体還元剤をタンク内に回収する制御が実行される。液体還元剤をタンク内に回収する方法としては、ポンプを逆回転させる方法や、液体還元剤の流れる方向を還元剤噴射弁側からタンク側に切り換える方法が知られている（例えば、特許文献１及び２を参照）。 Here, if the liquid reducing agent remains in the reducing agent injection valve and the reducing agent supply passage even after the internal combustion engine is stopped, the remaining urea aqueous solution freezes and expands in volume, causing the reducing agent injection valve and the like to freeze. may be damaged. Therefore, when the internal combustion engine is stopped, control is executed to collect the liquid reducing agent remaining in the reducing agent supply device into the tank. Known methods for recovering the liquid reducing agent in the tank include a method of rotating the pump in reverse and a method of switching the flow direction of the liquid reducing agent from the side of the reducing agent injection valve to the side of the tank (for example, Patent Document 1: and 2).

特開２０１０－１８５３３４号公報JP 2010-185334 A 特開２０１０－０２４８９６号公報JP 2010-024896 A

ここで、液体還元剤を回収する際、還元剤供給通路内の液体還元剤の吸い戻し量は、主として還元剤供給通路側の容量、還元剤噴射弁の噴射孔の面積の和、リターン通路側の容量、リターン通路の最小流路面積、及びポンプの駆動により生じる負圧により決定される。還元剤供給通路の長さは車両ごとに様々であるため、還元剤供給通路側の容量は車両ごとに異なる。リターン通路側の液体還元剤が還元剤供給通路側の液体還元剤よりも先に吸い戻された場合、その後は、リターン通路側にはタンク内の空気が吸引される。そうすると、液体還元剤に比べて空気の方が吸引されやすいために、還元剤供給通路側の液体還元剤よりも空気が優先的に吸い戻されてしまい、還元剤供給通路側に液体還元剤が残りやすくなる。 Here, when recovering the liquid reducing agent, the amount of liquid reducing agent sucked back in the reducing agent supply passage is mainly the sum of the capacity of the reducing agent supply passage side, the area of the injection hole of the reducing agent injection valve, and the sum of the area of the injection hole of the reducing agent injection valve, capacity, the minimum flow area of the return passage, and the negative pressure generated by driving the pump. Since the length of the reducing agent supply passage varies from vehicle to vehicle, the capacity on the reducing agent supply passage side differs from vehicle to vehicle. When the liquid reducing agent on the return passage side is sucked back earlier than the liquid reducing agent on the reducing agent supply passage side, the air in the tank is sucked back into the return passage side thereafter. In this case, since air is more easily sucked than the liquid reducing agent, the air is preferentially sucked back rather than the liquid reducing agent on the reducing agent supply passage side, and the liquid reducing agent is sucked back on the reducing agent supply passage side. It becomes easy to remain.

本発明は、上記問題に鑑みてなされたものであり、還元剤供給装置内の液体還元剤の回収後における液体還元剤の残留量を低減可能な還元剤供給装置を提供することを目的とする。 SUMMARY OF THE INVENTION It is an object of the present invention to provide a reducing agent supply device capable of reducing the residual amount of liquid reducing agent after recovery of the liquid reducing agent in the reducing agent supply device. .

上記課題を解決するために、本発明のある観点によれば、タンク内の液体還元剤を吸い上げて圧送するポンプと、ポンプにより圧送される液体還元剤を内燃機関の排気通路に噴射する還元剤噴射弁と、ポンプと還元剤噴射弁とを接続する還元剤供給通路と、ポンプにより圧送される液体還元剤の一部をタンクに戻すために還元剤供給通路から分岐して設けられたリターン通路と、を備え、内燃機関の運転時には液体還元剤を還元剤噴射弁側に供給する制御が実行され、内燃機関の停止時には液体還元剤を吸い戻してタンクに回収する制御が実行される還元剤供給装置において、リターン通路の途中に、還元剤供給通路内に生じる圧力によって流路面積が変化する流路面積可変機構を備え、流路面積可変機構は、液体還元剤を回収する制御の実行時に、リターン通路を閉じることなく液体還元剤を供給する制御の実行時に比べて流路面積を小さくして、液体還元剤を通過させる還元剤供給装置が提供される In order to solve the above problems, according to one aspect of the present invention, there are provided a pump that sucks up a liquid reducing agent in a tank and pumps it, and a reducing agent that injects the liquid reducing agent pumped by the pump into an exhaust passage of an internal combustion engine. an injection valve, a reducing agent supply passage connecting the pump and the reducing agent injection valve, and a return passage branched from the reducing agent supply passage for returning part of the liquid reducing agent pressure-fed by the pump to the tank. , wherein control is executed to supply the liquid reducing agent to the reducing agent injection valve side when the internal combustion engine is running, and control is executed to suck back the liquid reducing agent and collect it in the tank when the internal combustion engine is stopped. In the supply device, a flow passage area variable mechanism is provided in the middle of the return passage, and the flow passage area variable mechanism changes the flow passage area according to the pressure generated in the reducing agent supply passage. A reducing agent supply device is provided in which the flow path area is made smaller than when control is executed to supply the liquid reducing agent without closing the return passage, and the liquid reducing agent passes through.

以上説明したように本発明によれば、還元剤供給装置内の液体還元剤の回収後における液体還元剤の残留量を低減することができる。 As described above, according to the present invention, it is possible to reduce the residual amount of the liquid reducing agent after recovery of the liquid reducing agent in the reducing agent supply device.

本発明の実施の形態に係る還元剤供給装置を適用した尿素ＳＣＲシステムの構成例を示す模式図である。1 is a schematic diagram showing a configuration example of a urea SCR system to which a reducing agent supply device according to an embodiment of the invention is applied; FIG. 同実施形態に係るオリフィス部の構成例を示す説明図である。It is an explanatory view showing an example of composition of an orifice part concerning the embodiment. 同実施形態に係るオリフィス部の動作を示す説明図である。It is explanatory drawing which shows operation|movement of the orifice part which concerns on the same embodiment. 還元剤供給装置の流路構成を示す模式図である。FIG. 3 is a schematic diagram showing a flow path configuration of a reducing agent supply device; 調節部材を用いたオリフィス部を示す説明図である。It is an explanatory view showing an orifice portion using an adjustment member. オリフィス部の変形例を示す説明図である。It is explanatory drawing which shows the modification of an orifice part. オリフィス部の変形例を示す説明図である。It is explanatory drawing which shows the modification of an orifice part.

以下に添付図面を参照しながら、本発明の好適な実施の形態について詳細に説明する。なお、本明細書及び図面において、実質的に同一の機能構成を有する構成要素については、同一の符号を付することにより重複説明を省略する。 Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

＜１．還元剤供給装置の全体構成＞
まず、本実施形態に係る還元剤供給装置を適用可能な尿素ＳＣＲシステムの全体構成の一例について説明する。図１は、尿素ＳＣＲシステム１０の構成例を示す模式図である。 <1. Overall Configuration of Reducing Agent Supply Device>
First, an example of the overall configuration of a urea SCR system to which the reducing agent supply device according to this embodiment can be applied will be described. FIG. 1 is a schematic diagram showing a configuration example of a urea SCR system 10. As shown in FIG.

尿素ＳＣＲシステム１０は、ディーゼルエンジン等に代表される内燃機関５の排気系に接続された排気管１１の途中に配設された選択還元触媒１３と、選択還元触媒１３よりも上流側で排気管１１内に尿素水溶液を噴射する還元剤供給装置３０とを備える。尿素ＳＣＲシステム１０は、例えば自動車等の車両に搭載され、内燃機関５から排出される排気中のＮＯXを、尿素水溶液を用いて還元することにより排気を浄化するシステムである。尿素水溶液としては、例えば凍結温度が最も低い、約３２．５％濃度の尿素水溶液が用いられる。この場合の凍結温度は、約－１１℃である。 The urea SCR system 10 includes a selective reduction catalyst 13 disposed in the middle of an exhaust pipe 11 connected to an exhaust system of an internal combustion engine 5 such as a diesel engine, and an exhaust pipe upstream of the selective reduction catalyst 13. 11 is provided with a reducing agent supply device 30 for injecting a urea aqueous solution. The urea SCR system 10 is a system that is mounted on a vehicle such as an automobile, for example, and purifies the exhaust gas by reducing NOx in the exhaust gas emitted from the internal combustion engine 5 using an aqueous urea solution. As the urea aqueous solution, for example, an approximately 32.5% concentration urea aqueous solution having the lowest freezing temperature is used. The freezing temperature in this case is about -11°C.

選択還元触媒１３は、内燃機関５の排気中に含まれるＮＯXを選択的に還元する機能を有する。例えば、選択還元触媒１３は、還元剤供給装置３０により供給される尿素水溶液が分解して生成されるアンモニアを吸着する。そして、選択還元触媒１３に流入する排気中のＮＯXは、アンモニアと還元反応することによって分解される。かかる選択還元触媒１３は、温度が活性温度を超える状態でＮＯXの還元効率が上昇し、温度が高いほどアンモニアの吸着可能量が減少する特性を有する。また、選択還元触媒１３は、吸着可能量に対する実際のアンモニアの吸着率が高いほど、ＮＯXの還元効率が高くなる特性を有する。 The selective reduction catalyst 13 has a function of selectively reducing NO X contained in the exhaust gas of the internal combustion engine 5 . For example, the selective reduction catalyst 13 adsorbs ammonia generated by decomposition of the urea aqueous solution supplied by the reducing agent supply device 30 . NO X in the exhaust flowing into the selective reduction catalyst 13 is decomposed through a reduction reaction with ammonia. The selective reduction catalyst 13 has a characteristic that the NO x reduction efficiency increases when the temperature exceeds the activation temperature, and the amount of ammonia that can be adsorbed decreases as the temperature increases. Further, the selective reduction catalyst 13 has a characteristic that the higher the actual ammonia adsorption rate with respect to the adsorbable amount, the higher the NO x reduction efficiency.

還元剤供給装置３０は、選択還元触媒１３よりも上流側の排気管１１内に尿素水溶液を供給する。尿素水溶液の供給量は、排気中に含まれるＮＯXの濃度及び選択還元触媒１３におけるアンモニアの吸着可能量等に基づいて、選択還元触媒１３の下流側に、ＮＯXあるいはアンモニアが流出しないように制御装置１００によって制御される。 The reducing agent supply device 30 supplies the aqueous urea solution into the exhaust pipe 11 on the upstream side of the selective reduction catalyst 13 . The amount of urea aqueous solution supplied is determined based on the concentration of NOx contained in the exhaust gas, the amount of ammonia that can be adsorbed by the selective reduction catalyst 13, etc., so that NOx or ammonia does not flow downstream of the selective reduction catalyst 13. It is controlled by the control device 100 .

この他、排気管１１には、排気温度センサ２１及びＮＯXセンサ２３等の各種センサが設けられてもよい。これらのセンサは、それぞれ、排気温度又はＮＯX濃度等の検出に用いられる。また、排気温度センサ２１によって検出される排気温度は、選択還元触媒１３の温度推定に用いられてもよい。 In addition, the exhaust pipe 11 may be provided with various sensors such as the exhaust temperature sensor 21 and the NO X sensor 23 . These sensors are used to detect exhaust temperature or NO x concentration, respectively. Also, the exhaust temperature detected by the exhaust temperature sensor 21 may be used to estimate the temperature of the selective reduction catalyst 13 .

＜２．還元剤供給装置＞
次に、本実施形態に係る還元剤供給装置３０の構成例について詳細に説明する。
還元剤供給装置３０は、尿素水溶液を貯蔵する貯蔵タンク５０と、尿素水溶液を圧送するポンプ４１と、流路切換弁３５と、選択還元触媒１３よりも上流側の排気管１１に固定された還元剤噴射弁３１とを備える。ポンプ４１及び還元剤噴射弁３１は、マイクロコンピュータ等を備えて構成される制御装置１００によって駆動制御される。貯蔵タンク５０には、尿素水溶液の温度を検出する温度センサ５１が設けられる。 <2. Reducing Agent Supply Device>
Next, a configuration example of the reducing agent supply device 30 according to this embodiment will be described in detail.
The reducing agent supply device 30 includes a storage tank 50 that stores the urea aqueous solution, a pump 41 that pressure-feeds the urea aqueous solution, a flow path switching valve 35, and a reducing agent fixed to the exhaust pipe 11 on the upstream side of the selective reduction catalyst 13. and an agent injection valve 31 . The pump 41 and the reducing agent injection valve 31 are driven and controlled by a control device 100 including a microcomputer or the like. The storage tank 50 is provided with a temperature sensor 51 that detects the temperature of the urea aqueous solution.

ポンプ４１は、第１の還元剤供給通路５８を介して、尿素水溶液を貯留する貯蔵タンク５０と接続される。また、ポンプ４１は、第２の還元剤供給通路５７を介して還元剤噴射弁３１と接続される。第２の還元剤供給通路５７には、還元剤噴射弁３１へ供給される尿素水溶液の圧力を検出する圧力センサ４３が設けられる。また、第２の還元剤供給通路５７には、他端が貯蔵タンク５０に接続されたリターン通路５９が接続されている。 The pump 41 is connected via a first reducing agent supply passage 58 to a storage tank 50 that stores the urea aqueous solution. Also, the pump 41 is connected to the reducing agent injection valve 31 via the second reducing agent supply passage 57 . A pressure sensor 43 that detects the pressure of the urea aqueous solution supplied to the reducing agent injection valve 31 is provided in the second reducing agent supply passage 57 . A return passage 59 having the other end connected to the storage tank 50 is connected to the second reducing agent supply passage 57 .

ポンプ４１としては、例えば電動式のダイヤフラムポンプやモータポンプが用いられる。制御装置１００は、第２の還元剤供給通路５７内の圧力、すなわち、還元剤噴射弁３１へ供給される尿素水溶液の圧力が所定の目標値で維持されるように、ポンプ４１の出力を制御する。例えば、制御装置１００は、第２の還元剤供給通路５７に設けられた圧力センサ４３により検出される圧力と目標値との差分に基づいて、ポンプ４１の出力をフィードバック制御する。 As the pump 41, for example, an electric diaphragm pump or motor pump is used. The control device 100 controls the output of the pump 41 so that the pressure in the second reducing agent supply passage 57, that is, the pressure of the urea aqueous solution supplied to the reducing agent injection valve 31, is maintained at a predetermined target value. do. For example, the control device 100 feedback-controls the output of the pump 41 based on the difference between the pressure detected by the pressure sensor 43 provided in the second reducing agent supply passage 57 and the target value.

リターン通路５９には、内部に絞り通路が形成されたオリフィス部７０が備えられている。リターン通路５９を介して貯蔵タンク５０に戻される尿素水溶液の流量が大きいと、ポンプ４１の要求出力が大きくなる。このため、絞り通路を有するオリフィス部７０をリターン通路５９に設け、第２の還元剤供給通路５７内の圧力を保持しやすくすることによって、ポンプ４１の要求出力が過度に大きくならないようになっている。また、ポンプ４１の要求出力が過度に大きくならないことにより、第２の還元剤供給通路５７内の圧力脈動が小さく抑えられる。 The return passage 59 is provided with an orifice portion 70 in which a throttle passage is formed. When the flow rate of the aqueous urea solution returned to the storage tank 50 via the return passage 59 is high, the required output of the pump 41 is increased. Therefore, an orifice portion 70 having a throttle passage is provided in the return passage 59 so that the pressure in the second reducing agent supply passage 57 can be easily maintained, thereby preventing the required output of the pump 41 from becoming excessively large. there is In addition, since the required output of the pump 41 does not become excessively large, the pressure pulsation in the second reducing agent supply passage 57 can be kept small.

流路切換弁３５は、ポンプ４１によって圧送される尿素水溶液の流れる方向を切り換える。流路切換弁３５は、例えば電磁弁を用いて構成され、制御装置１００によって駆動される。本実施形態では、流路切換弁３５を用いて、ポンプ４１の吸入側と第１の還元剤供給通路５８、及び、ポンプ４１の吐出側と第２の還元剤供給通路５７をそれぞれ接続する第１の状態と、ポンプ４１の吐出側と第１の還元剤供給通路５８、及び、ポンプ４１の吸入側と第２の還元剤供給通路５７をそれぞれ接続する第２の状態とに切り換えられる。 The channel switching valve 35 switches the direction of flow of the urea aqueous solution pressure-fed by the pump 41 . The channel switching valve 35 is configured using, for example, an electromagnetic valve and driven by the control device 100 . In this embodiment, the channel switching valve 35 is used to connect the suction side of the pump 41 to the first reducing agent supply passage 58 and the discharge side of the pump 41 to the second reducing agent supply passage 57 . 1 and a second state in which the discharge side of the pump 41 and the first reducing agent supply passage 58 and the suction side of the pump 41 and the second reducing agent supply passage 57 are connected, respectively.

排気管１１内への尿素水溶液の噴射制御を行う場合には、尿素水溶液が貯蔵タンク５０側から還元剤噴射弁３１側へ流れるように、流路切換弁３５が第１の状態に保持される。また、還元剤供給装置３０内の尿素水溶液を貯蔵タンク５０に回収する場合には、尿素水溶液が還元剤噴射弁３１側から貯蔵タンク５０側へ流れるように、流路切換弁３５が第２の状態に保持される。 When performing injection control of the urea aqueous solution into the exhaust pipe 11, the flow path switching valve 35 is held in the first state so that the urea aqueous solution flows from the storage tank 50 side to the reducing agent injection valve 31 side. . When the urea aqueous solution in the reducing agent supply device 30 is recovered to the storage tank 50, the flow path switching valve 35 is set to the second position so that the urea aqueous solution flows from the reducing agent injection valve 31 side to the storage tank 50 side. state.

例えば、流路切換弁３５が、非通電状態において第１の状態となり、通電状態において第２の状態となる場合、尿素水溶液の噴射制御時には流路切換弁３５は非通電状態で維持され、尿素水溶液の回収時に制御装置１００は流路切換弁３５を通電状態とする。なお、流路切換弁３５を用いる代わりに、逆回転可能なポンプを用いたり、回収用の第２のポンプを用いたりすることによって、尿素水溶液が回収可能になっていてもよい。 For example, when the flow path switching valve 35 is in the first state in the non-energized state and in the second state in the energized state, the flow path switching valve 35 is maintained in the non-energized state during the injection control of the urea aqueous solution. When the aqueous solution is recovered, the control device 100 energizes the flow path switching valve 35 . Instead of using the channel switching valve 35, the urea aqueous solution may be recovered by using a pump that can rotate in reverse or by using a second recovery pump.

還元剤噴射弁３１としては、例えば、通電制御により開弁又は閉弁が切り換えられる電磁式開閉弁が用いられる。かかる還元剤噴射弁３１は、電磁コイルを備え、当該電磁コイルへの通電により発生する磁力によって弁体が移動して開弁する構造を有している。制御装置１００は、例えば、第２の還元剤供給通路５７内の圧力が所定の目標値となるようにポンプ４１の出力を制御しつつ、尿素水溶液の目標噴射量に応じて還元剤噴射弁３１の開弁時間をデューティ制御する。 As the reducing agent injection valve 31, for example, an electromagnetic open/close valve that is switched between opening and closing by energization control is used. The reducing agent injection valve 31 includes an electromagnetic coil, and has a structure in which a valve body is moved by a magnetic force generated by energizing the electromagnetic coil to open the valve. The control device 100, for example, controls the output of the pump 41 so that the pressure in the second reducing agent supply passage 57 reaches a predetermined target value, and operates the reducing agent injection valve 31 according to the target injection amount of the aqueous urea solution. duty control the valve opening time.

なお、還元剤噴射弁３１は、図１に示したように、排気が流れる排気管１１の本流部分に取り付けられてもよいし、排気管１１の本流部分から分岐した分岐部分に取り付けられてもよい。この場合、尿素水溶液は、分岐管を通じて排気管１１の本流部分に供給される。 The reducing agent injection valve 31 may be attached to the main stream portion of the exhaust pipe 11 through which the exhaust gas flows, as shown in FIG. good. In this case, the urea aqueous solution is supplied to the main stream portion of the exhaust pipe 11 through the branch pipe.

制御装置１００は、ポンプ４１、流路切換弁３５及び還元剤噴射弁３１をそれぞれ駆動する複数の駆動回路を備える。それぞれの駆動回路は、マイクロコンピュータ等から送信される信号に基づいて動作して、ポンプ４１、流路切換弁３５及び還元剤噴射弁３１を駆動する。 The control device 100 includes a plurality of drive circuits that drive the pump 41, the channel switching valve 35, and the reducing agent injection valve 31, respectively. Each drive circuit operates based on a signal transmitted from a microcomputer or the like to drive the pump 41 , the flow path switching valve 35 and the reducing agent injection valve 31 .

制御装置１００の一部又は全部は、例えば、マイクロコンピュータ又はマイクロプロセッサユニット等で構成されていてもよい。また、制御装置１００の一部又は全部は、ファームウェア等の更新可能なもので構成されていてもよく、また、ＣＰＵ等からの指令によって実行されるプログラムモジュール等であってもよい。 A part or all of the control device 100 may be configured by, for example, a microcomputer or a microprocessor unit. Also, part or all of the control device 100 may be composed of an updatable device such as firmware, or may be a program module or the like that is executed by a command from a CPU or the like.

＜３．オリフィス部＞
次に、リターン通路５９に備えられたオリフィス部７０について詳細に説明する。 <3. Orifice section>
Next, the orifice portion 70 provided in the return passage 59 will be described in detail.

図２は、本実施形態に係る還元剤供給装置３０に備えられたオリフィス部７０の構成例を示す模式図である。図２において、右側（矢印Ａの方向）が第２の還元剤供給通路５７側であり、左側（矢印Ｂの方向）が貯蔵タンク５０側である。図２は、ポンプ４１により尿素水溶液を還元剤噴射弁３１側に圧送している期間のオリフィス部７０の状態を示している。 FIG. 2 is a schematic diagram showing a configuration example of the orifice part 70 provided in the reducing agent supply device 30 according to this embodiment. In FIG. 2, the right side (direction of arrow A) is the second reducing agent supply passage 57 side, and the left side (direction of arrow B) is the storage tank 50 side. FIG. 2 shows the state of the orifice portion 70 while the pump 41 is pumping the urea aqueous solution to the reducing agent injection valve 31 side.

オリフィス部７０は、第１の通路部材７１、第２の通路部材７５、変位部材７８及び付勢部材７３を備える。このうち、変位部材７８及び付勢部材７３は、流路面積可変機構８０を構成する。第１の通路部材７１は、軸方向の両端（図の左右）に開口する内部通路７１ａを有する。第２の通路部材７５は、軸方向の一端側（図の左側）に開口する内部通路７５ａと、軸方向の他端側（図の右側）に開口する変位部材摺動孔７５ｂと、一端が変位部材摺動孔７５ｂの周面に開口し他端が内部通路７５ａに開口する絞り通路７５ｃと、内部通路７５ａと変位部材摺動孔７５ｂとを軸方向に接続する連通孔７５ｄとを有する。 The orifice portion 70 includes a first passage member 71 , a second passage member 75 , a displacement member 78 and a biasing member 73 . Among them, the displacement member 78 and the biasing member 73 constitute a flow passage area varying mechanism 80 . The first passage member 71 has internal passages 71a that open at both axial ends (left and right in the drawing). The second passage member 75 includes an internal passage 75a that opens at one end in the axial direction (left side in the drawing), a displacement member sliding hole 75b that opens at the other end in the axial direction (right side in the drawing), It has a throttle passage 75c that opens to the peripheral surface of the displacement member sliding hole 75b and the other end of which opens to the internal passage 75a, and a communicating hole 75d that axially connects the internal passage 75a and the displacement member sliding hole 75b.

第１の通路部材７１の内部通路７１ａの一端側は第２の還元剤供給通路５７側のリターン通路５９に連通し、他端側は第２の通路部材７５の変位部材摺動孔７５ｂに連通している。第２の通路部材７５の変位部材摺動孔７５ｂの一端側は第１の通路部材７１の内部通路７１ａに連通し、他端側は連通孔７５ｄに連通している。第２の通路部材７５の内部通路７５ａの一端側は貯蔵タンク５０側のリターン通路５９に連通し、他端側は連通孔７５ｄに連通している。 One end of the internal passage 71 a of the first passage member 71 communicates with the return passage 59 on the side of the second reducing agent supply passage 57 , and the other end communicates with the displacement member sliding hole 75 b of the second passage member 75 . are doing. One end of the displacement member slide hole 75b of the second passage member 75 communicates with the internal passage 71a of the first passage member 71, and the other end communicates with the communication hole 75d. One end of the internal passage 75a of the second passage member 75 communicates with the return passage 59 on the storage tank 50 side, and the other end communicates with the communication hole 75d.

第２の通路部材７５の変位部材摺動孔７５ｂには、変位部材７８が進退移動可能に保持されている。変位部材摺動孔７５ｂの直径は、第１の通路部材７１の内部通路７１ａの直径よりも大きくなっている。変位部材７８と第１の通路部材７１との間には付勢部材７３としてのコイルスプリングが備えられ、変位部材７８は、付勢部材７３によって内部通路７５ａ側に付勢されている。なお、付勢部材７３は、コイルスプリングに限られない。 A displacement member 78 is held in the displacement member sliding hole 75b of the second passage member 75 so as to be movable back and forth. The diameter of the displacement member sliding hole 75 b is larger than the diameter of the internal passage 71 a of the first passage member 71 . A coil spring as a biasing member 73 is provided between the displacement member 78 and the first passage member 71, and the displacement member 78 is biased by the biasing member 73 toward the internal passage 75a. Note that the biasing member 73 is not limited to a coil spring.

連通孔７５ｄの直径は、変位部材摺動孔７５ｂの直径よりも小さくなっており、付勢部材７３により付勢される変位部材７８は、連通孔７５ｄの周囲の当接部７７に当接して位置決めされている。変位部材７８は、内部通路７８ａを有する。内部通路７８ａの一端は、第１の通路部材７１側に位置する変位部材７８の軸方向の一端側に開口し、他端は変位部材７８の外周面に開口する。変位部材７８が当接部７７に当接した状態において、変位部材７８の内部通路７８ａと絞り通路７５ｃとが連通する。 The diameter of the communication hole 75d is smaller than the diameter of the displacement member sliding hole 75b, and the displacement member 78 biased by the biasing member 73 contacts the contact portion 77 around the communication hole 75d. positioned. The displacement member 78 has an internal passageway 78a. One end of the internal passage 78 a opens to one end in the axial direction of the displacement member 78 located on the side of the first passage member 71 , and the other end opens to the outer peripheral surface of the displacement member 78 . When the displacement member 78 is in contact with the contact portion 77, the internal passage 78a of the displacement member 78 communicates with the throttle passage 75c.

図２に示す状態では、第２の還元剤供給通路５７に圧送される尿素水溶液の一部がリターン通路５９を介して貯蔵タンク５０に戻される際に、変位部材７８の内部通路７８ａ及び絞り通路７５ｃを通過する。これらの内部通路７８ａ及び絞り通路７５ｃは、流路面積が小さくされていることから、尿素水溶液の流通に抵抗が与えられ、第２の還元剤供給通路５７内の圧力が保持されやすくなる。このとき、変位部材７８の第１の通路部材７１側の端面には、付勢部材７３の付勢力と第２の還元剤供給通路５７内の圧力に起因する正圧とが作用し、変位部材７８の貯蔵タンク５０側の端面には大気圧が作用するため、変位部材７８は、当接部７７に当接した状態で維持される。 In the state shown in FIG. 2, when part of the aqueous urea solution pressure-fed to the second reducing agent supply passage 57 is returned to the storage tank 50 via the return passage 59, the internal passage 78a of the displacement member 78 and the throttle passage Pass 75c. Since the internal passage 78a and the throttle passage 75c have a small passage area, resistance is provided to the flow of the aqueous urea solution, and the pressure in the second reducing agent supply passage 57 is easily maintained. At this time, the biasing force of the biasing member 73 and the positive pressure caused by the pressure in the second reducing agent supply passage 57 act on the end face of the displacement member 78 on the side of the first passage member 71, and the displacement member Since the atmospheric pressure acts on the end face of the storage tank 50 side of the displacement member 78 , the displacement member 78 is maintained in contact with the contact portion 77 .

図３は、尿素水溶液の回収制御中のオリフィス部７０の状態を示している。ポンプ４１により尿素水溶液を貯蔵タンク５０内に吸い戻している間、第２の還元剤供給通路５７内には負圧が発生する。この負圧により、変位部材７８は、付勢部材７３の付勢力に抗して第１の通路部材７１側に移動する。これにより、変位部材７８の外周面に開口する内部通路７８ａと、当該内部通路７８ａに対向する絞り通路７５ｃとの境界により形成される流路面積は、変位部材７８が当接部７７に当接した状態での流路面積よりも小さくなる。つまり、尿素水溶液の回収制御中、オリフィス部７０を通過して貯蔵タンク５０側から第２の還元剤供給通路５７側へと流れる尿素水溶液に付与される抵抗が高められ、リターン通路５９内の尿素水溶液は第２の還元剤供給通路５７内の尿素水溶液よりも吸い戻されにくくなっている。 FIG. 3 shows the state of the orifice part 70 during recovery control of the aqueous urea solution. While the urea aqueous solution is sucked back into the storage tank 50 by the pump 41 , a negative pressure is generated inside the second reducing agent supply passage 57 . This negative pressure causes the displacement member 78 to move toward the first passage member 71 against the biasing force of the biasing member 73 . As a result, the flow passage area formed by the boundary between the internal passage 78a that opens to the outer peripheral surface of the displacement member 78 and the throttle passage 75c that faces the internal passage 78a is such that the displacement member 78 contacts the contact portion 77. It is smaller than the flow channel area in the closed state. That is, during the recovery control of the urea aqueous solution, the resistance given to the urea aqueous solution flowing through the orifice portion 70 from the storage tank 50 side to the second reducing agent supply passage 57 side is increased, and the urea in the return passage 59 is increased. The aqueous solution is less likely to be sucked back than the aqueous urea solution in the second reducing agent supply passage 57 .

ただし、尿素水溶液の回収制御中、オリフィス部７０内の流路が完全に閉じられると、リターン通路５９内の尿素水容液を回収することが困難になることから、変位部材７８が変位した状態においてもオリフィス部７０内の流路が完全に閉じられることがないように設計される。 However, if the flow path in the orifice portion 70 is completely closed during the recovery control of the urea aqueous solution, it becomes difficult to recover the aqueous urea solution in the return passage 59. Therefore, the displacement member 78 is displaced. is designed so that the flow path in the orifice portion 70 is not completely closed.

尿素水溶液を回収する際、第２の還元剤供給通路５７内の尿素水溶液の吸い戻し量は、主として第２の還元剤供給通路５７側の容量、還元剤噴射弁３１の噴射孔の面積の和、リターン通路５９側の容量、リターン通路５９の最小流路面積、及びポンプ４１の駆動により生じる負圧により決定される。リターン通路５９内の尿素水溶液が、第２の還元剤供給通路５７内の尿素水溶液よりも早く回収されてしまうと、以降、リターン通路５９には貯蔵タンク５０側から空気が吸引されることになって、第２の還元剤供給通路５７内の尿素水溶液が回収されにくくなる。 When recovering the urea aqueous solution, the amount of the urea aqueous solution sucked back in the second reducing agent supply passage 57 is mainly the sum of the capacity on the side of the second reducing agent supply passage 57 and the area of the injection hole of the reducing agent injection valve 31. , the capacity of the return passage 59 , the minimum passage area of the return passage 59 , and the negative pressure generated by driving the pump 41 . If the urea aqueous solution in the return passage 59 is recovered earlier than the urea aqueous solution in the second reducing agent supply passage 57, air will be sucked into the return passage 59 from the storage tank 50 side thereafter. As a result, the aqueous urea solution in the second reducing agent supply passage 57 becomes difficult to recover.

図４は、還元剤供給装置３０の流路構成を模式的に示す図である。一般的に、第２の還元剤供給通路５７とリターン通路５９との分岐点５６から還元剤噴射弁３１の先端までの容量Ｖａは、当該分岐点５６からリターン通路５９の端部までの容量Ｖｂよりも大きい。このため、第２の還元剤供給通路５７側の最小流路面積と、リターン通路５９側の最小流路面積とが同等である場合、リターン通路５９内の尿素水溶液が第２の還元剤供給通路５７内の尿素水溶液よりも早く吸い戻される。これを防ぐためには、リターン通路５９側の最小流路面積を第２の還元剤供給通路５７側の最小流路面積よりも小さくする必要がある。 FIG. 4 is a diagram schematically showing the flow channel configuration of the reducing agent supply device 30. As shown in FIG. In general, the capacity Va from the branch point 56 between the second reducing agent supply passage 57 and the return passage 59 to the tip of the reducing agent injection valve 31 is the capacity Vb from the branch point 56 to the end of the return passage 59. bigger than Therefore, when the minimum channel area on the side of the second reducing agent supply passage 57 and the minimum channel area on the side of the return passage 59 are the same, the urea aqueous solution in the return passage 59 is the second reducing agent supply passage. It is sucked back faster than the aqueous urea solution in 57. In order to prevent this, it is necessary to make the minimum channel area on the return passage 59 side smaller than the minimum channel area on the second reducing agent supply passage 57 side.

第２の還元剤供給通路５７側の最小流路面積は、還元剤噴射弁３１の噴射孔の面積の和であるため、オリフィス部７０の変位部材７８が変位して流路面積が小さくなるときの流路面積が、少なくとも、還元剤噴射弁３１の噴射孔の面積の和よりも小さくなるように設計される。具体的には、ポンプ４１の駆動により生じる負圧と付勢部材７３の付勢力とにより、変位部材７８の変位量及び変位状態での流路面積が定まることから、少なくともリターン通路５９側の尿素水溶液が第２の還元剤供給通路５７側の尿素水溶液よりも先に吸い戻されないように、付勢部材７３の付勢力や内部通路７８ａあるいは絞り通路７５ｃの断面積が設計される。これにより、第２の還元剤供給通路５７内の尿素水溶液の残留量を低減することができる。 Since the minimum channel area on the side of the second reducing agent supply passage 57 is the sum of the areas of the injection holes of the reducing agent injection valve 31, when the displacement member 78 of the orifice portion 70 is displaced and the channel area becomes smaller, is designed to be at least smaller than the sum of the areas of the injection holes of the reducing agent injection valve 31 . Specifically, the negative pressure generated by driving the pump 41 and the biasing force of the biasing member 73 determine the amount of displacement of the displacement member 78 and the flow path area in the displaced state. The biasing force of the biasing member 73 and the cross-sectional area of the internal passage 78a or the throttle passage 75c are designed so that the aqueous solution is not sucked back before the urea aqueous solution on the second reducing agent supply passage 57 side. Thereby, the residual amount of the urea aqueous solution in the second reducing agent supply passage 57 can be reduced.

望ましくは、第２の還元剤供給通路５７側の尿素水溶液と、リターン通路５９側の尿素水溶液とが、同時期に回収されるように設計されるとよい。これにより、第２の還元剤供給通路５７及びリターン通路５９内の尿素水溶液の残留量を低減することができる。 Desirably, the urea aqueous solution on the second reducing agent supply passage 57 side and the urea aqueous solution on the return passage 59 side are designed to be recovered at the same time. Thereby, the residual amount of the urea aqueous solution in the second reducing agent supply passage 57 and the return passage 59 can be reduced.

尿素水溶液の回収制御中の変位部材７８の位置、つまり、内部通路７８ａと絞り通路７５ｃとの境界により形成される流路面積は、調節部材を用いて調節することもできる。図５は、尿素水溶液の回収制御中のリターン通路５９内の最小流路面積を調節する調節部材７９を備えた例を示す。調節部材７９は、開口部７９ａを有し、当該開口部７９ａが第１の通路部材７１の内部通路７１ａに連通するようにして、第１の通路部材７１の端面に配置される。かかる調節部材７９の厚さ（軸方向の幅）を調節することにより、付勢部材７３の付勢力が同じであっても変位部材７８の位置を調節することができる。 The position of the displacement member 78 during recovery control of the aqueous urea solution, that is, the channel area formed by the boundary between the internal passage 78a and the throttle passage 75c can also be adjusted using an adjusting member. FIG. 5 shows an example provided with an adjusting member 79 for adjusting the minimum flow area in the return passage 59 during recovery control of the urea aqueous solution. The adjustment member 79 has an opening 79 a and is arranged on the end surface of the first passage member 71 so that the opening 79 a communicates with the internal passage 71 a of the first passage member 71 . By adjusting the thickness (width in the axial direction) of the adjusting member 79, the position of the displacement member 78 can be adjusted even if the biasing force of the biasing member 73 is the same.

なお、調節部材７９は、第１の通路部材７１の内部通路７１ａ内に取り付けられてもよく、変位部材摺動孔７５ｂ内に取り付けられてもよい。 The adjustment member 79 may be attached inside the internal passage 71a of the first passage member 71, or may be attached inside the displacement member sliding hole 75b.

図６及び図７は、オリフィス部９０の変形例を示す。変形例にかかるオリフィス部９０は、付勢部材を用いずに、変位部材９８の自重と第２の還元剤供給通路５７内に生じる負圧とにより変位部材９８が変位して流路面積が変化する流路面積可変機構８０を備える。図６及び図７において、上側（矢印Ａの方向）が第２の還元剤供給通路５７側であり、下側（矢印Ｂの方向）が貯蔵タンク５０側である。 6 and 7 show a modification of the orifice portion 90. FIG. The orifice portion 90 according to the modification does not use an urging member, and the displacement member 98 is displaced by the weight of the displacement member 98 and the negative pressure generated in the second reducing agent supply passage 57 to change the passage area. A flow passage area variable mechanism 80 is provided. 6 and 7, the upper side (direction of arrow A) is the second reducing agent supply passage 57 side, and the lower side (direction of arrow B) is the storage tank 50 side.

変形例に係るオリフィス部７０において、変位部材９８の上面には環状突出部９９が形成されるとともに、その一部に、一つ又は複数の溝部９５が形成されている。ポンプ４１により尿素水溶液が第２の還元剤供給通路５７内に供給されている間、変位部材９８は自重により落下して、支持部９２上に位置する（図６）。一方、ポンプ４１により尿素水溶液が吸い戻され、第２の還元剤供給通路５７内に負圧が発生すると、当該負圧により変位部材９８が浮上する（図７）。この状態では、オリフィス部９０の最小流路面積が溝部９５の流路面積の和となって、図６の状態に比べて小さくなる。これにより、リターン通路５９内の尿素水溶液が吸い戻されにくくなって、第２の還元剤供給通路５７内の尿素水溶液の残留量を低減することができる。 In the orifice portion 70 according to the modified example, an annular projecting portion 99 is formed on the upper surface of the displacement member 98, and one or more groove portions 95 are formed in a part thereof. While the urea aqueous solution is being supplied into the second reducing agent supply passage 57 by the pump 41, the displacement member 98 drops due to its own weight and is positioned on the support portion 92 (FIG. 6). On the other hand, when the urea aqueous solution is sucked back by the pump 41 and negative pressure is generated in the second reducing agent supply passage 57, the negative pressure causes the displacement member 98 to float (FIG. 7). In this state, the minimum flow area of the orifice portion 90 is the sum of the flow area of the groove portion 95, which is smaller than the state shown in FIG. As a result, the aqueous urea solution in the return passage 59 is less likely to be sucked back, and the residual amount of the aqueous urea solution in the second reducing agent supply passage 57 can be reduced.

変形例にかかるオリフィス部７０の場合、環状突出部９９の高さ、あるいは、溝部９５の深さ又は幅を調節することにより、尿素水溶液の回収制御中のリターン通路５９の最小流路面積を調節することができる。この場合、環状突出部９９あるいは溝部９５が調節部として機能する。 In the case of the orifice portion 70 according to the modified example, by adjusting the height of the annular projecting portion 99 or the depth or width of the groove portion 95, the minimum flow area of the return passage 59 during recovery control of the aqueous urea solution is adjusted. can do. In this case, the annular projecting portion 99 or the groove portion 95 functions as an adjusting portion.

以上説明したとおり、本実施形態に係る還元剤供給装置３０は、尿素水溶液の回収制御時のリターン通路５９側の最小流路面積を、尿素水溶液の噴射制御時のリターン通路５９側の最小流路面積よりも小さくする流路面積可変機構８０を備える。このため、第２の還元剤供給通路５７内の尿素水溶液よりも先にリターン通路５９内の尿素水溶液が吸い戻されることを防ぎ、少なくとも第２の還元剤供給通路５７内に尿素水溶液が残留することを抑制することができる。 As described above, in the reducing agent supply device 30 according to the present embodiment, the minimum flow passage area on the return passage 59 side during the urea aqueous solution recovery control is set to the minimum flow passage area on the return passage 59 side during the urea aqueous solution injection control. A flow passage area variable mechanism 80 is provided to make the flow passage area smaller than the area. Therefore, the urea aqueous solution in the return passage 59 is prevented from being sucked back before the urea aqueous solution in the second reducing agent supply passage 57, and the urea aqueous solution remains in at least the second reducing agent supply passage 57. can be suppressed.

以上、添付図面を参照しながら本発明の好適な実施形態について詳細に説明したが、本発明はかかる例に限定されない。本発明の属する技術の分野における通常の知識を有する者であれば、特許請求の範囲に記載された技術的思想の範疇内において、各種の変更例または修正例に想到し得ることは明らかであり、これらについても、当然に本発明の技術的範囲に属するものと了解される。 Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

５：内燃機関、３０：還元剤供給装置、３１：還元剤噴射弁、４１：ポンプ、５０：貯蔵タンク、５７：第２の還元剤供給通路、５９：リターン通路、７０：オリフィス部、７３：付勢部材、７８：変位部材、７８ａ：内部通路、７９：調節部材、８０：流路面積可変機構
5: internal combustion engine, 30: reducing agent supply device, 31: reducing agent injection valve, 41: pump, 50: storage tank, 57: second reducing agent supply passage, 59: return passage, 70: orifice section, 73: Biasing member 78: Displacement member 78a: Internal passage 79: Adjusting member 80: Flow passage area variable mechanism

Claims (4)

タンク（５０）内の液体還元剤を吸い上げて圧送するポンプ（４１）と、前記ポンプ（４１）により圧送される前記液体還元剤を内燃機関（５）の排気通路に噴射する還元剤噴射弁（３１）と、前記ポンプ（４１）と前記還元剤噴射弁（３１）とを接続する還元剤供給通路（５７）と、前記ポンプ（４１）により圧送される前記液体還元剤の一部を前記タンク（５０）に戻すために前記還元剤供給通路（５７）から分岐して設けられたリターン通路（５９）と、を備え、
前記内燃機関（５）の運転時には前記液体還元剤を前記還元剤噴射弁（３１）側に供給する制御が実行され、前記内燃機関（５）の停止時には前記液体還元剤を吸い戻して前記タンク（５０）に回収する制御が実行される還元剤供給装置（３０）において、
前記リターン通路（５９）の途中に、前記還元剤供給通路（５７）内に生じる圧力によって流路面積が変化する流路面積可変機構（８０）を備え、
前記流路面積可変機構（８０）は、
前記液体還元剤を回収する制御の実行時に、前記リターン通路（５９）を閉じることなく、前記液体還元剤を供給する制御の実行時に比べて前記流路面積を小さくして、前記液体還元剤を通過させる、
ことを特徴とする、還元剤供給装置。 A pump (41) for sucking up the liquid reducing agent in the tank (50) and pumping it, and a reducing agent injection valve ( 31); a reducing agent supply passage (57) connecting the pump (41) and the reducing agent injection valve (31); a return passage (59) branched from the reducing agent supply passage (57) for returning to (50);
During operation of the internal combustion engine (5), control is executed to supply the liquid reducing agent to the reducing agent injection valve (31) side, and when the internal combustion engine (5) is stopped, the liquid reducing agent is sucked back into the tank. In the reducing agent supply device (30) in which the recovery control is executed in (50),
In the middle of the return passage (59), a passage area variable mechanism (80) that changes the passage area according to the pressure generated in the reducing agent supply passage (57) is provided,
The flow passage area variable mechanism (80)
When the control for recovering the liquid reducing agent is executed, the return passage (59) is not closed, and the flow passage area is made smaller than when the control for supplying the liquid reducing agent is executed, so that the liquid reducing agent is discharged. let through,
A reducing agent supply device characterized by: 前記流路面積可変機構（８０）は、
前記リターン通路（５９）内を、前記還元剤供給通路（５７）側及び前記タンク（５０）側に移動可能な変位部材（７８）を含み、
前記変位部材（７８）は、
前記液体還元剤を供給する制御の実行時に前記タンク（５０）側に位置するとともに、
前記液体還元剤を回収する制御の実行時に前記還元剤供給通路（５７）内に生じる負圧により前記還元剤供給通路（５７）側に移動して、前記リターン通路（５９）を閉じることなく、前記流路面積を小さくする、
ことを特徴とする、請求項１に記載の還元剤供給装置。 The flow passage area variable mechanism (80)
including a displacement member (78) movable in the return passage (59) toward the reducing agent supply passage (57) side and the tank (50) side;
The displacement member (78) is
Positioned on the side of the tank (50) when the control for supplying the liquid reducing agent is executed,
Due to the negative pressure generated in the reducing agent supply passage (57) during execution of the control for recovering the liquid reducing agent, the reducing agent supply passage (57) moves toward the reducing agent supply passage (57) without closing the return passage (59). reducing the flow channel area;
2. The reducing agent supply device according to claim 1, characterized in that: 前記流路面積可変機構（８０）は、
前記変位部材（７８）が前記還元剤供給通路（５７）側に移動した際の前記変位部材（７８）の位置を設定する調節部（７９）を含む、
ことを特徴とする、請求項２に記載の還元剤供給装置。 The flow passage area variable mechanism (80)
an adjustment part (79) for setting the position of the displacement member (78) when the displacement member (78) moves toward the reducing agent supply passage (57);
3. The reducing agent supply device according to claim 2, characterized in that: 前記変位部材（７８）が前記還元剤供給通路（５７）側に移動した際の前記流路面積が、少なくとも、前記還元剤噴射弁（３１）の噴射孔の面積の和よりも小さくなるように設定される、
ことを特徴とする、請求項２又は３に記載の還元剤供給装置。 The flow path area when the displacement member (78) moves toward the reducing agent supply passage (57) is at least smaller than the sum of the areas of the injection holes of the reducing agent injection valve (31). is set,
4. The reducing agent supply device according to claim 2 or 3, characterized in that:
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013148028A (en) 2012-01-20 2013-08-01 Bosch Corp Reducing agent supply device
JP2014095337A (en) 2012-11-09 2014-05-22 Bosch Corp Reductant supply device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013148028A (en) 2012-01-20 2013-08-01 Bosch Corp Reducing agent supply device
JP2014095337A (en) 2012-11-09 2014-05-22 Bosch Corp Reductant supply device

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