JP2013148028A - Reducing agent supply device - Google Patents

Reducing agent supply device Download PDF

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JP2013148028A
JP2013148028A JP2012009667A JP2012009667A JP2013148028A JP 2013148028 A JP2013148028 A JP 2013148028A JP 2012009667 A JP2012009667 A JP 2012009667A JP 2012009667 A JP2012009667 A JP 2012009667A JP 2013148028 A JP2013148028 A JP 2013148028A
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reducing agent
passage
valve
agent supply
liquid reducing
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JP5914004B2 (en
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Kunihiro Chiba
訓弘 千葉
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Bosch Corp
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Bosch Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1406—Storage means for substances, e.g. tanks or reservoirs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1473—Overflow or return means for the substances, e.g. conduits or valves for the return path
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a reducing agent supply device capable of preventing a liquid reducing agent recovered in a storage tank from flowing backward into a pump after recovering the liquid reducing agent.SOLUTION: In a reducing agent supply device constituted such that control in which a liquid reducing agent is pumped to a reducing agent spraying side by a pump when operating an internal combustion engine, the liquid reducing agent is recovered to a storage tank by the pump when stopping the internal combustion engine, is executed, an aperture part where a flowing channel area is reduced is arranged in the middle of a return channel, a valve part constituted so as to shut off the return channel with the lowering of a pressure in a reducing agent supply channel and the return channel during recovering control of the liquid reducing agent and so as to open the return channel after the completion of the recovering control of the liquid reducing agent is arranged in the reducing agent supply channel side more than the aperture part.

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ものである。特に、内燃機関の停止時に、装置内に残留する液体還元剤を貯蔵タンクに回収する制御が実行されるように構成された還元剤供給装置に関するものである。   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. In particular, the present invention relates to a reducing agent supply device configured to execute control for collecting a liquid reducing agent remaining in the apparatus in a storage tank when the internal combustion engine is stopped.

従来、車両等に搭載された内燃機関から排出される排気を浄化する排気浄化装置として、排気に含まれる窒素酸化物（ＮＯX）の還元反応を促進する還元触媒と、還元触媒よりも上流側の排気管内に液体還元剤を供給するための還元剤供給装置とを備えた排気浄化装置が知られている。かかる排気浄化装置に用いられる還元剤供給装置の一態様として、貯蔵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部とを備えたものがある。 Conventionally, as an exhaust gas purification device that purifies exhaust gas discharged from an internal combustion engine mounted on a vehicle or the like, a reduction catalyst that promotes a reduction reaction of nitrogen oxide (NO x ) contained in the exhaust gas, and an upstream side of the reduction catalyst There is known an exhaust emission control device provided with a reducing agent supply device for supplying a liquid reducing agent into the exhaust pipe. As one aspect of the reducing agent supply device used in such an exhaust purification device, a pump that sucks up and pumps the liquid reducing agent in the storage tank, and a reducing agent injection unit that injects the liquid reducing agent pumped by the pump into the exhaust passage. There is something with.

このような還元剤供給装置において、目標噴射量に相当する量の液体還元剤を精度良く噴射できるようにするために、ポンプによって圧送される液体還元剤を、還元剤供給通路から分岐するリターン通路を介して貯蔵タンクに循環させながら還元剤供給通路内の圧力を一定に保った状態で、還元剤噴射部による噴射制御を実行することが行われている。   In such a reducing agent supply apparatus, in order to accurately inject the liquid reducing agent corresponding to the target injection amount, the return passage that branches the liquid reducing agent pumped by the pump from the reducing agent supply passage. In the state where the pressure in the reducing agent supply passage is kept constant while being circulated to the storage tank through the injection tank, injection control by the reducing agent injection unit is performed.

ここで、液体還元剤として例えば尿素水溶液が用いられる場合、内燃機関の停止後にもポンプや、還元剤噴射部内に尿素水溶液が残留していると、水分の蒸発等によって尿素水溶液の濃度が上昇し、尿素水溶液が析出して流路が閉塞するおそれがある。また、寒冷地においては、残留する尿素水溶液の凍結による体積の膨張によって、ポンプ等が破損するおそれがある。そのために、内燃機関の停止時に、還元剤供給装置内に残留する液体還元剤を貯蔵タンク内に回収する制御を実行するようになっている。   Here, when a urea aqueous solution is used as the liquid reducing agent, for example, if the urea aqueous solution remains in the pump or the reducing agent injection section even after the internal combustion engine is stopped, the concentration of the urea aqueous solution increases due to evaporation of moisture or the like. The urea aqueous solution may be deposited and the flow path may be blocked. In a cold district, the pump and the like may be damaged due to volume expansion due to freezing of the remaining urea aqueous solution. Therefore, when the internal combustion engine is stopped, control is performed to recover the liquid reducing agent remaining in the reducing agent supply device into the storage tank.

液体還元剤を貯蔵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、ポンプを逆回転させる代わりに、液体還元剤の流れる向きが還元剤噴射部側から貯蔵タンク側となるように流路の接続を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。）。いずれの方法を採用する場合においても、還元剤供給通路内の還元剤を効率よく回収するために、貯蔵タンクから還元剤供給通路側への液体還元剤の流れを阻止する逆止め弁がリターン通路に設けられている。   As a method of collecting the liquid reducing agent in the storage tank, instead of rotating the pump in the reverse direction or rotating the pump in the reverse direction, the flow direction of the liquid reducing agent is changed from the reducing agent injection unit side to the storage tank side. A method of switching the connection of flow paths is known (see, for example, Patent Documents 1 and 2). In either case, a check valve that prevents the flow of the liquid reducing agent from the storage tank to the reducing agent supply passage side is provided with a return passage in order to efficiently recover the reducing agent in the reducing agent supply passage. Is provided.

特開２０１０−１８５３３４号公報 （段落［００３４］）JP 2010-185334 A (paragraph [0034]) 特開２０１０−０２４８９６号公報 （段落［００４６］）JP 2010-024896 (paragraph [0046])

しかしながら、液体還元剤の回収制御後には、ポンプ及び還元剤供給通路内は液体の代わりに気体が封入された状態になる。この状態で、当該気体の温度が下がると、還元剤供給通路内の気体の凝縮により負圧が発生し、その負圧によって貯蔵タンク内の液体還元剤の液体還元剤がポンプ内に吸い込まれる場合がある。これにより、液体還元剤の回収が不十分となるおそれがあった。   However, after recovery control of the liquid reducing agent, the pump and the reducing agent supply passage are filled with gas instead of liquid. When the temperature of the gas decreases in this state, a negative pressure is generated due to the condensation of the gas in the reducing agent supply passage, and the liquid reducing agent in the storage tank is sucked into the pump by the negative pressure. There is. Thereby, there was a possibility that recovery of a liquid reducing agent might become insufficient.

本発明の発明者はこのような問題にかんがみて、リターン通路内に所定の弁部を設けることによりこのような問題を解決できることを見出し、本発明を完成させたものである。すなわち、本発明は、液体還元剤の回収後に、貯蔵タンク内に回収された液体還元剤がポンプ内に逆流することを防ぐことができる還元剤供給装置を提供することを目的とする。   In view of such a problem, the inventors of the present invention have found that such a problem can be solved by providing a predetermined valve portion in the return passage, and have completed the present invention. That is, an object of the present invention is to provide a reducing agent supply device capable of preventing the liquid reducing agent recovered in the storage tank from flowing back into the pump after the liquid reducing agent is recovered.

本発明によれば、貯蔵タンク内の液体還元剤を吸い上げて圧送するポンプと、前記ポンプにより圧送される前記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部と、前記ポンプと前記還元剤噴射部とを接続する還元剤供給通路と、前記還元剤供給通路から分岐して前記ポンプにより圧送される前記液体還元剤の一部を前記貯蔵タンクに戻すためのリターン通路と、を備え、前記内燃機関の運転時には前記ポンプにより前記液体還元剤を前記還元剤噴射部側に圧送し、前記内燃機関の停止時には前記ポンプにより前記液体還元剤を前記貯蔵タンクに回収する制御が実行されるように構成された還元剤供給装置において、前記リターン通路の途中に、流路面積を小さくした絞り部を備えるとともに、前記絞り部よりも前記還元剤供給通路側に、前記液体還元剤の回収制御時には前記還元剤供給通路及び前記リターン通路内の圧力の低下に伴い前記リターン通路を遮断する一方、前記液体還元剤の回収制御終了後には前記リターン通路を開放するように構成された弁部を備えた還元剤供給装置が提供され、上述した問題を解決することができる。   According to the present invention, a pump that sucks up and pumps the liquid reducing agent in the storage tank, a reducing agent injection unit that injects the liquid reducing agent pumped by the pump into an exhaust passage of an internal combustion engine, the pump, and the pump A reducing agent supply passage connecting the reducing agent injection unit; and a return passage for returning a part of the liquid reducing agent branched from the reducing agent supply passage and pumped by the pump to the storage tank. When the internal combustion engine is in operation, the pump is used to pump the liquid reducing agent to the reducing agent injection unit, and when the internal combustion engine is stopped, the pump is used to collect the liquid reducing agent in the storage tank. In the reducing agent supply apparatus configured as described above, a reducing portion having a reduced flow path area is provided in the middle of the return passage, and the reducing agent supply passage is more than the restricting portion. Further, during the recovery control of the liquid reducing agent, the return passage is shut off as the pressure in the reducing agent supply passage and the return passage decreases, and the return passage is opened after the liquid reducing agent recovery control ends. A reducing agent supply device having a valve portion configured as described above is provided, and the above-described problems can be solved.

すなわち、本発明の還元剤供給装置は、液体還元剤の回収制御時にリターン通路を遮断する一方、液体還元剤の回収制御終了後にリターン通路を開放する弁部を備えているために、回収制御時においては効率的に負圧が生じて液体還元剤を貯蔵タンク内に吸い戻すことができるとともに、回収制御終了後には還元剤供給通路内が常に大気圧状態になるため、貯蔵タンク内の液体還元剤がポンプ内に逆流することを防ぐことができる。   That is, the reducing agent supply device of the present invention includes a valve portion that shuts off the return passage during the liquid reducing agent recovery control and opens the return passage after the liquid reducing agent recovery control ends. In this case, the negative pressure is efficiently generated and the liquid reducing agent can be sucked back into the storage tank, and after the recovery control is completed, the reducing agent supply passage is always in the atmospheric pressure state. The agent can be prevented from flowing back into the pump.

また、本発明の還元剤供給装置を構成するにあたり、前記弁部は、前記リターン通路を遮断する遮断部材と、前記リターン通路を開放する方向に前記遮断部材を常時付勢する弾性部材と、を備え、前記圧力の低下時に発生する負圧によって、前記弾性部材の付勢力に抗して前記遮断部材が移動し、前記リターン通路を遮断するように構成されてなることが好ましい。
このように弁部を構成することにより、液体還元剤の回収制御時にリターン通路を遮断する一方、液体還元剤の回収制御終了後にリターン通路を開放する弁部を容易に構成することができる。 Further, in configuring the reducing agent supply device of the present invention, the valve portion includes a blocking member that blocks the return passage, and an elastic member that constantly biases the blocking member in a direction to open the return passage. It is preferable that the blocking member is moved against the urging force of the elastic member by the negative pressure generated when the pressure is reduced, and the return passage is blocked.
By configuring the valve portion in this way, it is possible to easily configure the valve portion that blocks the return passage during the liquid reducing agent recovery control and opens the return passage after the liquid reducing agent recovery control ends.

また、本発明の還元剤供給装置を構成するにあたり、前記リターン通路のうちの前記弁部よりも前記貯蔵タンク側の容量が、前記液体還元剤の回収を開始してから前記弁部によって前記リターン通路が遮断されるまで、前記弁部に前記液体還元剤が存在するように設定されてなることが好ましい。
このようにリターン通路を構成することにより、リターン通路が遮断されるまでにリターン通路が気体に置き換えられて、リターン通路が遮断されにくくなることを防ぐことができる。 Further, in configuring the reducing agent supply device of the present invention, the capacity of the storage tank side with respect to the valve portion of the return passage is started by the valve portion after the recovery of the liquid reducing agent is started. It is preferable that the liquid reducing agent is set in the valve portion until the passage is blocked.
By configuring the return path in this way, it is possible to prevent the return path from being replaced by gas until the return path is blocked, and the return path from becoming difficult to be blocked.

本発明の実施の形態にかかる還元剤供給装置の構成を概略的に示す図である。It is a figure which shows roughly the structure of the reducing agent supply apparatus concerning embodiment of this invention. 第１の実施の形態の弁部の構成を説明するために示す。It shows in order to demonstrate the structure of the valve part of 1st Embodiment. 第１の実施の形態の弁部の動作を説明するために示す図である。It is a figure shown in order to demonstrate operation | movement of the valve part of 1st Embodiment. 液体還元剤の流れ及び弁部の状態を説明するために示す図である。It is a figure shown in order to demonstrate the flow of a liquid reducing agent, and the state of a valve part. 液体還元剤の流れ及び弁部の状態を説明するために示す図である。It is a figure shown in order to demonstrate the flow of a liquid reducing agent, and the state of a valve part. 第２の実施の形態の弁部の構成及び動作を説明するために示す図である。It is a figure shown in order to demonstrate the structure and operation | movement of the valve part of 2nd Embodiment. 第３の実施の形態の弁部の構成及び動作を説明するために示す図である。It is a figure shown in order to demonstrate the structure and operation | movement of the valve part of 3rd Embodiment.

以下、本発明にかかる還元剤供給装置に関する実施の形態について、図面に基づいて具体的に説明する。
なお、各図において同じ符号が付されているものは同じ構成要素を表しており、適宜説明が省略されている場合がある。 Hereinafter, an embodiment relating to a reducing agent supply apparatus according to the present invention will be specifically described with reference to the drawings.
In addition, what is attached | subjected with the same code | symbol in each figure represents the same component, and description may be abbreviate | omitted suitably.

［第１の実施の形態］
１．還元剤供給装置の全体的構成
図１は、本発明の第１の実施の形態にかかる還元剤供給装置２０の構成を説明するために示す図である。
図１において、還元剤供給装置２０が備えられた排気浄化装置１０は、排気中のＮＯXを浄化するための装置であり、図示しないディーゼルエンジン等の内燃機関の排気通路３に設けられている。排気浄化装置１０は、排気通路３の途中に介装された還元触媒１３と、還元触媒１３よりも上流側の排気通路３内に液体還元剤を供給するための還元剤供給装置２０とを備えている。 [First Embodiment]
1. Overall Configuration of Reducing Agent Supply Device FIG. 1 is a view for explaining the configuration of a reducing agent supply device 20 according to the first embodiment of the present invention.
In FIG. 1, an exhaust purification device 10 provided with a reducing agent supply device 20 is a device for purifying NO x in exhaust gas, and is provided in an exhaust passage 3 of an internal combustion engine such as a diesel engine (not shown). . The exhaust purification device 10 includes a reduction catalyst 13 interposed in the middle of the exhaust passage 3 and a reducing agent supply device 20 for supplying a liquid reducing agent into the exhaust passage 3 upstream of the reduction catalyst 13. ing.

還元触媒１３は、排気中のＮＯXの分解を促進する機能を有する触媒であり、液体還元剤から生成される還元成分を吸着するとともに、触媒に流れ込む排気中のＮＯXを還元成分によって選択的に還元する触媒である。本実施の形態の還元剤供給装置２０は、液体還元剤として尿素水溶液が用いられるものであり、尿素水溶液が分解することにより還元成分としてのアンモニアが生成されるようになっている。 The reduction catalyst 13 is a catalyst having a function of promoting the decomposition of NO x in the exhaust, adsorbs the reducing component generated from the liquid reducing agent, and selectively reduces the NO x in the exhaust flowing into the catalyst by the reducing component. It is a catalyst that reduces to The reducing agent supply apparatus 20 of the present embodiment uses a urea aqueous solution as a liquid reducing agent, and ammonia as a reducing component is generated when the urea aqueous solution is decomposed.

還元剤供給装置２０は、液体還元剤が収容される貯蔵タンク２１と、液体還元剤を圧送するポンプユニット３０と、液体還元剤を排気通路３内に噴射する還元剤噴射部として電磁噴射弁２５とを備えている。ポンプユニット３０は、電動ポンプ２３及び流路切換弁３３を備えている。電磁噴射弁２５及び電動ポンプ２３、流路切換弁３３は、電子制御装置（ＥＣＵ）４０によって駆動制御が行われるものとなっている。   The reducing agent supply device 20 includes a storage tank 21 that stores the liquid reducing agent, a pump unit 30 that pumps the liquid reducing agent, and an electromagnetic injection valve 25 as a reducing agent injection unit that injects the liquid reducing agent into the exhaust passage 3. And. The pump unit 30 includes an electric pump 23 and a flow path switching valve 33. The electromagnetic injection valve 25, the electric pump 23, and the flow path switching valve 33 are controlled by an electronic control unit (ECU) 40.

電動ポンプ２３と貯蔵タンク２１とは第１の還元剤供給通路２７によって接続され、電動ポンプ２３と電磁噴射弁２５とは第２の還元剤供給通路２８によって接続されている。電動ポンプ２３と、第１の還元剤供給通路２７及び第２の還元剤供給通路２８とは、流路切換弁３３を介して接続されている。第１の還元剤供給通路２７の貯蔵タンク２１側の端部は、液体還元剤の吸い上げを可能にするために、貯蔵タンク２１の底面近傍に位置している。   The electric pump 23 and the storage tank 21 are connected by a first reducing agent supply passage 27, and the electric pump 23 and the electromagnetic injection valve 25 are connected by a second reducing agent supply passage 28. The electric pump 23 is connected to the first reducing agent supply passage 27 and the second reducing agent supply passage 28 via a flow path switching valve 33. The end of the first reducing agent supply passage 27 on the side of the storage tank 21 is located in the vicinity of the bottom surface of the storage tank 21 so that the liquid reducing agent can be sucked up.

流路切換弁３３は、電動ポンプ２３によって圧送される液体還元剤が流れる方向を、貯蔵タンク２１側から電磁噴射弁２５側に流れる正方向と、電磁噴射弁２５側から貯蔵タンク２１側に流れる逆方向とに切換える機能を有している。本実施の形態にかかる還元剤供給装置２０において、流路切換弁３３は、非通電状態で第１の還元剤供給通路２７を電動ポンプ２３の入り口側２３ａに連通するとともに第２の還元剤供給通路２８を電動ポンプ２３の出口側２３ｂに連通する一方、通電状態で第１の還元剤供給通路２７を電動ポンプ２３の出口側２３ｂに連通するとともに第２の還元剤供給通路２８を電動ポンプ２３の入り口側２３ａに連通するように構成されている。   The flow path switching valve 33 flows in the forward direction in which the liquid reducing agent pumped by the electric pump 23 flows from the storage tank 21 side to the electromagnetic injection valve 25 side, and from the electromagnetic injection valve 25 side to the storage tank 21 side. It has a function of switching to the reverse direction. In the reducing agent supply device 20 according to the present embodiment, the flow path switching valve 33 communicates the first reducing agent supply passage 27 to the inlet side 23a of the electric pump 23 in a non-energized state and supplies the second reducing agent supply. While the passage 28 communicates with the outlet side 23b of the electric pump 23, the first reducing agent supply passage 27 communicates with the outlet side 23b of the electric pump 23 while being energized, and the second reducing agent supply passage 28 communicates with the electric pump 23. It is comprised so that it may communicate with the entrance side 23a.

すなわち、内燃機関の運転状態においては、液体還元剤が電磁噴射弁２５側に供給されるように、流路切換弁３３への通電は行われない。一方、内燃機関の停止時においては、還元剤供給装置２０内の液体還元剤が貯蔵タンク２１に回収されるように、流路切換弁３３に対して通電される。   That is, in the operation state of the internal combustion engine, the flow path switching valve 33 is not energized so that the liquid reducing agent is supplied to the electromagnetic injection valve 25 side. On the other hand, when the internal combustion engine is stopped, the flow path switching valve 33 is energized so that the liquid reducing agent in the reducing agent supply device 20 is collected in the storage tank 21.

なお、内燃機関の停止時に、液体還元剤を貯蔵タンク２１に回収可能とする構成は、流路切換弁３３を設ける例に限られない。例えば、逆回転可能な電動ポンプ２３を用いることによって液体還元剤を回収可能に構成することができる。   The configuration in which the liquid reducing agent can be recovered in the storage tank 21 when the internal combustion engine is stopped is not limited to the example in which the flow path switching valve 33 is provided. For example, the liquid reducing agent can be collected by using the electric pump 23 capable of rotating in reverse.

また、第２の還元剤供給通路２８の途中には、他端が貯蔵タンク２１に接続されたリターン通路２９が分岐して設けられている。リターン通路２９の貯蔵タンク２１側の端部は、貯蔵タンク２１内の気相部分に接続されている。
なお、貯蔵タンク２１にはエアブリザード等が設けられることにより、内部の圧力が大気圧で保たれるように構成されている。 In addition, a return passage 29 having the other end connected to the storage tank 21 is branched in the middle of the second reducing agent supply passage 28. An end of the return passage 29 on the storage tank 21 side is connected to a gas phase portion in the storage tank 21.
The storage tank 21 is provided with an air blizzard or the like so that the internal pressure is maintained at atmospheric pressure.

リターン通路２９の途中には、流路面積が小さくされた絞り部３７が設けられ、第２の還元剤供給通路２８内の圧力を保持できるようになっている。また、絞り部３７よりも第２の還元剤供給通路２８側のリターン通路２９には、液体還元剤の噴射制御時、すなわち、電磁噴射弁２５側への液体還元剤の圧送時及びポンプ２３の停止時にリターン通路２９を開放し、液体還元剤の貯蔵タンク２１への回収時にリターン通路２９を遮断する弁部３５が設けられている。弁部３５の詳細については後述する。   In the middle of the return passage 29, a throttle portion 37 having a reduced flow path area is provided so that the pressure in the second reducing agent supply passage 28 can be maintained. The return passage 29 closer to the second reducing agent supply passage 28 than the throttling portion 37 is provided with the liquid reducing agent injection control, that is, when the liquid reducing agent is pumped to the electromagnetic injection valve 25 side and the pump 23. A valve portion 35 is provided that opens the return passage 29 when stopped, and shuts off the return passage 29 when the liquid reducing agent is recovered into the storage tank 21. Details of the valve portion 35 will be described later.

電動ポンプ２３は、ＥＣＵ４０による通電制御によって、所定の流量の液体還元剤を圧送する。液体還元剤の噴射制御時においては、電磁噴射弁２５に供給される液体還元剤の圧力Ｐｕがあらかじめ設定された所定の目標圧力Ｐｕ＿ｔｇｔで維持されるように、電動ポンプ２３の出力がフィードバック制御される。具体的に、第２の還元剤供給通路２８に圧送される液体還元剤を、リターン通路２９を介して貯蔵タンク２１に循環させながら、ＥＣＵ４０は、第２の還元剤供給通路２８に設けられた圧力センサ３１によって検出される圧力Ｐｕと、あらかじめ設定された所定の目標圧力Ｐｕ＿ｔｇｔとの差分ΔＰｕに基づいて電動ポンプ２３の出力をＰＩＤ制御する。また、液体還元剤を貯蔵タンク２１に回収する場合においては、ＥＣＵ４０は、例えば、あらかじめ定められた出力で電動ポンプ２３を制御する。   The electric pump 23 pumps a liquid reducing agent at a predetermined flow rate by energization control by the ECU 40. During the injection control of the liquid reducing agent, the output of the electric pump 23 is feedback controlled so that the pressure Pu of the liquid reducing agent supplied to the electromagnetic injection valve 25 is maintained at a predetermined target pressure Pu_tgt set in advance. The Specifically, the ECU 40 is provided in the second reducing agent supply passage 28 while circulating the liquid reducing agent fed to the second reducing agent supply passage 28 to the storage tank 21 through the return passage 29. The output of the electric pump 23 is PID controlled based on the difference ΔPu between the pressure Pu detected by the pressure sensor 31 and a predetermined target pressure Pu_tgt set in advance. Further, when the liquid reducing agent is collected in the storage tank 21, the ECU 40 controls the electric pump 23 with a predetermined output, for example.

なお、本実施の形態にかかる還元剤供給装置２０においてはポンプユニット３０内に圧力センサ３１が設けられているが、第２の還元剤供給通路２８のどの位置に設けられていても構わない。   In the reducing agent supply device 20 according to the present embodiment, the pressure sensor 31 is provided in the pump unit 30, but may be provided at any position in the second reducing agent supply passage 28.

電磁噴射弁２５は、通電制御によって開閉制御が行われ、所定量の液体還元剤を排気通路３内に噴射する。本実施の形態にかかる還元剤供給装置２０において、ＥＣＵ４０は、所定の演算式に基づいて目標噴射量Ｑｄｖ＿ｔｇｔを求めるとともに、液体還元剤の圧力Ｐｕが目標圧力Ｐｕ＿ｔｇｔとなっていることを前提として、あらかじめ定められた噴射サイクルごとに、目標噴射量Ｑｄｖ＿ｔｇｔに応じた駆動デューティ比を決定して、電磁噴射弁２５の通電制御を行う。電磁噴射弁２５の駆動デューティ比とは、一噴射サイクル中の開弁時間の割合を意味する。   The electromagnetic injection valve 25 is controlled to open and close by energization control, and injects a predetermined amount of liquid reducing agent into the exhaust passage 3. In the reducing agent supply apparatus 20 according to the present embodiment, the ECU 40 obtains the target injection amount Qdv_tgt based on a predetermined arithmetic expression and assumes that the pressure Pu of the liquid reducing agent is the target pressure Pu_tgt. The drive duty ratio corresponding to the target injection amount Qdv_tgt is determined for each predetermined injection cycle, and energization control of the electromagnetic injection valve 25 is performed. The drive duty ratio of the electromagnetic injection valve 25 means the ratio of the valve opening time in one injection cycle.

２．弁部
（１）構成
図２は、本実施の形態にかかる還元剤供給装置２０のリターン通路２９に設けられた弁部３５の構成について説明するために示す図である。この図２は、リターン通路２９のうちの絞り部３７及び弁部３５が設けられた部分の断面図を示している。 2. Configuration of Valve Unit (1) FIG. 2 is a diagram for explaining the configuration of the valve unit 35 provided in the return passage 29 of the reducing agent supply device 20 according to the present embodiment. FIG. 2 shows a cross-sectional view of a portion of the return passage 29 where the throttle portion 37 and the valve portion 35 are provided.

図２において、リターン通路２９を構成する通路本体５０の内周面には第１の係止突部５１及び第２の係止突部５３が設けられている。第１の係止突部５１は、第２の係止突部５３よりも貯蔵タンク２１側に位置している。これらの第１の係止突部５１及び第２の係止突部５３は、それぞれ、液体還元剤の流路となる開口部５３ａ、５３ａを有している。   In FIG. 2, a first locking protrusion 51 and a second locking protrusion 53 are provided on the inner peripheral surface of the passage main body 50 constituting the return passage 29. The first locking protrusion 51 is located closer to the storage tank 21 than the second locking protrusion 53. Each of the first locking protrusion 51 and the second locking protrusion 53 has openings 53a and 53a that serve as a flow path for the liquid reducing agent.

第１の係止突部５１及び第２の係止突部５３の間の領域には、ピストンバルブ５５及びバルブスプリング５７が収容されている。ピストンバルブ５５は、その外周面において通路本体５０の内周面と摺動しながら、通路本体５０内を移動可能になっている。また、バルブスプリング５７は、その一端が第２の係止突部５３に当接するとともに他端がピストンバルブ５５に当接し、ピストンバルブ５５を貯蔵タンク２１側に付勢する。このとき、第１の係止突部５１によって、ピストンバルブ５５の貯蔵タンク２１側への最大移動位置が規定されている。   A piston valve 55 and a valve spring 57 are accommodated in a region between the first locking projection 51 and the second locking projection 53. The piston valve 55 is movable in the passage main body 50 while sliding on the outer peripheral surface of the piston valve 55 with the inner peripheral surface of the passage main body 50. One end of the valve spring 57 abuts on the second locking projection 53 and the other end abuts on the piston valve 55 to urge the piston valve 55 toward the storage tank 21. At this time, the maximum movement position of the piston valve 55 toward the storage tank 21 is defined by the first locking projection 51.

ピストンバルブ５５の中央部には、液体還元剤の流路となる、軸方向に設けられた通過孔５５Ａが形成されている。この通過孔５５Ａは、第２の係止突部５３側の大径部５５Ａａと、第１の係止突部５１側の小径部５５Ａｂとを有する段付の通過孔５５Ａとして形成されている。このうちの小径部５５Ａｂが絞り部３７としての機能を有している。また、大径部５５Ａａの第２の係止突部５３側の開口縁部はシート部５５Ｂとして構成され、通路本体５０内に固定されたロッド部５９の先端面がシート部５５Ｂに当接したときに、通過孔５５Ａ、すなわち、リターン通路２９が遮断されるようになっている。本実施の形態においては、ピストンバルブ５５が遮断部材を構成し、バルブスプリング５７が弾性部材を構成している。   In the central portion of the piston valve 55, a passage hole 55A provided in the axial direction is formed which serves as a flow path for the liquid reducing agent. The passage hole 55A is formed as a stepped passage hole 55A having a large diameter portion 55Aa on the second locking projection 53 side and a small diameter portion 55Ab on the first locking projection 51 side. Among these, the small diameter portion 55Ab functions as the throttle portion 37. The opening edge of the large-diameter portion 55Aa on the second locking projection 53 side is configured as a seat portion 55B, and the distal end surface of the rod portion 59 fixed in the passage main body 50 contacts the seat portion 55B. Sometimes, the passage hole 55A, that is, the return passage 29 is blocked. In the present embodiment, the piston valve 55 constitutes a blocking member, and the valve spring 57 constitutes an elastic member.

（２）動作
図３（ａ）〜（ｃ）は、液体還元剤の噴射制御時、回収制御時、及びポンプ停止時それぞれにおける弁部３５の状態を示している。
液体還元剤の噴射制御時においては、図３（ａ）に示すように、ピストンバルブ５５よりも第２の還元剤供給通路２８側の圧力Ｐｕ（以下、この領域の圧力を「上流側圧力」と言う。）が目標圧力Ｐｕ＿ｔｇｔ付近まで高められているために、当該上流側圧力Ｐｕとバルブスプリング５７の付勢力によってピストンバルブ５５が第１の係止突部５１側に保持された状態となる。したがって、弁部３５は開かれ、リターン通路２９は開放状態となって、液体還元剤は貯蔵タンク２１側へと流出する。 (2) Operation FIGS. 3A to 3C show the state of the valve portion 35 at the time of liquid reductant injection control, recovery control, and pump stop.
During the injection control of the liquid reducing agent, as shown in FIG. 3A, the pressure Pu on the second reducing agent supply passage 28 side of the piston valve 55 (hereinafter, the pressure in this region is referred to as “upstream pressure”). Is increased to near the target pressure Pu_tgt, the piston valve 55 is held on the first locking projection 51 side by the upstream pressure Pu and the urging force of the valve spring 57. . Accordingly, the valve portion 35 is opened, the return passage 29 is opened, and the liquid reducing agent flows out to the storage tank 21 side.

また、液体還元剤の回収制御時においては、図３（ｂ）に示すように、上流側圧力Ｐｕは負圧状態となり、この負圧によってバルブスプリング５７の付勢力に抗してピストンバルブ５５が第２の係止突部５３側に移動する。したがって、弁部３５が閉じられ、リターン通路２９が遮断状態となる。   Further, at the time of liquid reductant recovery control, as shown in FIG. 3B, the upstream pressure Pu becomes a negative pressure state, and the piston valve 55 resists the urging force of the valve spring 57 by this negative pressure. It moves to the second locking projection 53 side. Therefore, the valve part 35 is closed and the return passage 29 is in a shut-off state.

さらに、液体還元剤の回収制御が終了して、電動ポンプ２３が停止すると、図３（ｃ）に示すように、上流側圧力Ｐｕが正圧に復帰するために、ピストンバルブ５５はバルブスプリング５７の付勢力によって再び貯蔵タンク２１側に移動する。したがって、弁部３５は開かれ、リターン通路２９は開放状態となる。   Furthermore, when the recovery control of the liquid reducing agent is finished and the electric pump 23 is stopped, the upstream side pressure Pu returns to the positive pressure as shown in FIG. It moves again to the storage tank 21 side by the urging force. Accordingly, the valve portion 35 is opened and the return passage 29 is opened.

図４（ａ）〜（ｂ）及び図５（ａ）〜（ｃ）は、弁部３５の動作に伴う、還元剤供給装置２０全体における液体還元剤の流れを示している。なお、図４（ａ）〜（ｂ）及び図５（ａ）〜（ｃ）においては、還元剤供給装置２０、特にポンプユニット３０の構成は簡略化して示されている。   4 (a) to 4 (b) and FIGS. 5 (a) to 5 (c) show the flow of the liquid reducing agent in the entire reducing agent supply apparatus 20 accompanying the operation of the valve unit 35. FIG. In FIGS. 4A to 4B and FIGS. 5A to 5C, the configuration of the reducing agent supply device 20, particularly the pump unit 30, is shown in a simplified manner.

内燃機関の始動前、すなわち、電動ポンプ２３の非作動状態においては、図４（ａ）に示すように、液体還元剤は貯蔵タンク２１内に収容され、還元剤供給装置２０内には残されていない。   Before the internal combustion engine is started, that is, when the electric pump 23 is not operated, the liquid reducing agent is accommodated in the storage tank 21 and left in the reducing agent supply device 20 as shown in FIG. Not.

内燃機関の始動後、すなわち、液体還元剤の噴射制御時においては、図４（ｂ）に示すように、貯蔵タンク２１内の液体還元剤は電動ポンプ２３によって吸い上げられて電磁噴射弁２５側に圧送される。このとき、弁部３５は開かれ、リターン通路２９は開放状態となるために、電磁噴射弁２５から噴射される液体還元剤を除いて、液体還元剤はリターン通路２９を介して貯蔵タンク２１に戻される。   After the internal combustion engine is started, that is, during the injection control of the liquid reducing agent, as shown in FIG. 4B, the liquid reducing agent in the storage tank 21 is sucked up by the electric pump 23 and moved to the electromagnetic injection valve 25 side. Pumped. At this time, since the valve portion 35 is opened and the return passage 29 is opened, the liquid reducing agent is supplied to the storage tank 21 via the return passage 29 except for the liquid reducing agent injected from the electromagnetic injection valve 25. Returned.

その後、内燃機関が停止すると、電動ポンプ２３によって液体還元剤の回収制御が開始される。液体還元剤の回収制御の開始時には、電磁噴射弁２５は開弁され、電磁噴射弁２５を介して排気通路から気体が吸い込まれるとともに、弁部３５が閉じられるまでの期間においては、リターン通路２９の貯蔵タンク２１側の端部から気体が吸い込まれ、液体還元剤が吸い戻され始める。   Thereafter, when the internal combustion engine is stopped, the electric pump 23 starts recovery control of the liquid reducing agent. At the start of the liquid reductant recovery control, the electromagnetic injection valve 25 is opened, gas is sucked from the exhaust passage through the electromagnetic injection valve 25, and the return passage 29 is maintained until the valve portion 35 is closed. Gas is sucked in from the end on the storage tank 21 side, and the liquid reducing agent begins to be sucked back.

そして、リターン通路２９に設けられた弁部３５は、未だ液体還元剤が充填された状態にあり、電磁噴射弁２５における気体の流入抵抗よりも弁部３５における液体の流入抵抗が大きくなるために、弁部３５に負圧が作用して弁部３５が閉じられる。その後は、図５（ｂ）に示すように、弁部３５が閉じられたまま、貯蔵タンク２１への液体還元剤の吸い戻しが続けられる。その結果、第１の還元剤供給通路２７、電磁ポンプ２３及び第２の還元剤供給通路２８内から液体還元剤が回収される。   The valve portion 35 provided in the return passage 29 is still filled with the liquid reducing agent, and the inflow resistance of the liquid in the valve portion 35 is larger than the inflow resistance of the gas in the electromagnetic injection valve 25. The negative pressure acts on the valve portion 35, and the valve portion 35 is closed. Thereafter, as shown in FIG. 5B, the liquid reducing agent is sucked back into the storage tank 21 while the valve portion 35 is closed. As a result, the liquid reducing agent is recovered from the first reducing agent supply passage 27, the electromagnetic pump 23, and the second reducing agent supply passage 28.

このとき、リターン通路２９内の液体還元剤の吸い戻しが早く行われて、極短時間にリターン通路２９内が気体で満たされてしまうと、弁部３５の前後の差圧が小さくなって、弁部３５が閉じられにくくなる。この状態では、液体還元剤の吸い戻しを効率的に行うことができなくなるおそれがあるため、負圧の作用によって弁部３５が閉じられるまでは弁部３５に液体還元剤が存在するように、リターン通路３５における弁部３５から貯蔵タンク２１側の端部までの容量が設定されている。   At this time, if the liquid reducing agent in the return passage 29 is sucked back quickly and the return passage 29 is filled with gas in a very short time, the differential pressure across the valve portion 35 becomes small, The valve part 35 becomes difficult to close. In this state, there is a possibility that the liquid reducing agent cannot be sucked back efficiently, so that the liquid reducing agent is present in the valve portion 35 until the valve portion 35 is closed by the action of the negative pressure. The capacity | capacitance from the valve part 35 in the return channel | path 35 to the edge part by the side of the storage tank 21 is set.

液体還元剤の回収制御が終了し、電磁ポンプ２３が停止すると、電磁ポンプ２３側から第２の還元剤供給通路２８に少量の気体が逆流し、第２の還元剤供給通路２８内は大気圧状態となる。そのため、図５（ｃ）に示すように、弁部３５が開かれ、リターン通路２９は開放されて、弁部３５付近に残留していた液体還元剤は貯蔵タンク２１側に移動し、自重により貯蔵タンク２１内に落下することとなる。このとき、弁部３５は開弁し、第２の還元剤供給通路２８内は速やかに負圧から正圧に復帰するため、電磁ポンプ２３内まで液体還元剤が逆流することはない。また、弁部３５における液体還元剤の流路が、貯蔵タンク２１側を下方にして配置されているために、液体還元剤が自重により落下しやすくなって、弁部３５に液体還元剤が残留することを防ぐこともできる。   When the recovery control of the liquid reducing agent is finished and the electromagnetic pump 23 is stopped, a small amount of gas flows backward from the electromagnetic pump 23 side to the second reducing agent supply passage 28, and the atmospheric pressure in the second reducing agent supply passage 28 is reached. It becomes a state. Therefore, as shown in FIG. 5 (c), the valve portion 35 is opened, the return passage 29 is opened, and the liquid reducing agent remaining in the vicinity of the valve portion 35 moves to the storage tank 21 side, due to its own weight. It will fall into the storage tank 21. At this time, the valve portion 35 is opened and the second reducing agent supply passage 28 quickly returns from the negative pressure to the positive pressure, so that the liquid reducing agent does not flow back into the electromagnetic pump 23. Further, since the flow path of the liquid reducing agent in the valve portion 35 is arranged with the storage tank 21 side downward, the liquid reducing agent is likely to drop due to its own weight, and the liquid reducing agent remains in the valve portion 35. Can also be prevented.

３．第１の実施の形態の還元剤供給装置によって得られる効果
以上説明したように、本実施の形態にかかる還元剤供給装置２０は、液体還元剤の回収制御時にリターン通路２９を遮断する一方、液体還元剤の回収制御終了後にリターン通路２９を開放する弁部３５を備えているために、回収制御時においては効率的に負圧が生じて液体還元剤を貯蔵タンク２１内に吸い戻すことができるとともに、回収制御終了後には第２の還元剤供給通路２８内が常に大気圧状態になって、貯蔵タンク２１内の液体還元剤が電磁ポンプ２３内に逆流することを防ぐことができる。したがって、電磁ポンプ２３内に残留した液体還元剤の凍結等による電磁ポンプ２３の破損を低減することができる。 3. Effects Obtained by the Reducing Agent Supply Device of the First Embodiment As described above, the reducing agent supply device 20 according to the present embodiment blocks the return passage 29 during the liquid reductant recovery control, Since the valve portion 35 that opens the return passage 29 after completion of the reducing agent recovery control is provided, a negative pressure is efficiently generated during the recovery control, and the liquid reducing agent can be sucked back into the storage tank 21. At the same time, after the recovery control is completed, the inside of the second reducing agent supply passage 28 is always in the atmospheric pressure state, and the liquid reducing agent in the storage tank 21 can be prevented from flowing back into the electromagnetic pump 23. Therefore, damage to the electromagnetic pump 23 due to freezing of the liquid reducing agent remaining in the electromagnetic pump 23 can be reduced.

また、本実施の形態にかかる還元剤供給装置２０においては、リターン通路２９のうちの弁部３５よりも貯蔵タンク２１側の容量を、液体還元剤の回収制御を開始してから弁部３５によってリターン通路２９が遮断されるまで、弁部３５に液体還元剤が存在するように設定することとしている。したがって、第２の還元剤供給通路２８内に発生する負圧によってリターン通路２９が確実に遮断されるため、液体還元剤の回収制御を効率的に行うことができる。   Further, in the reducing agent supply device 20 according to the present embodiment, the capacity of the storage tank 21 side of the return passage 29 relative to the valve unit 35 is set by the valve unit 35 after the liquid reducing agent recovery control is started. Until the return passage 29 is blocked, the valve portion 35 is set so that the liquid reducing agent exists. Therefore, since the return passage 29 is reliably blocked by the negative pressure generated in the second reducing agent supply passage 28, the liquid reducing agent recovery control can be performed efficiently.

また、本実施の形態にかかる還元剤供給装置２０においては、弁部３５における液体還元剤の流路が、貯蔵タンク２１側を下方にして配置することとしているために、液体還元剤が自重により落下しやすくなって、電動ポンプ２３の停止後に弁部３５に液体還元剤が残留することを防ぐこともできる。   Further, in the reducing agent supply apparatus 20 according to the present embodiment, since the liquid reducing agent flow path in the valve portion 35 is arranged with the storage tank 21 side facing downward, the liquid reducing agent is caused by its own weight. It becomes easy to fall, and it can also prevent that a liquid reducing agent remains in the valve part 35 after the electric pump 23 stops.

［第２の実施の形態］
本発明の第２の実施の形態にかかる還元剤供給装置は、リターン通路２９に設けられる弁部３５Ａの構成が第１の実施の形態にかかる還元剤供給装置に設けられた弁部とは異なっている。 [Second Embodiment]
In the reducing agent supply device according to the second embodiment of the present invention, the configuration of the valve portion 35A provided in the return passage 29 is different from the valve portion provided in the reducing agent supply device according to the first embodiment. ing.

図６（ａ）〜（ｂ）は、本実施の形態にかかる還元剤供給装置に備えられた弁部３５Ａの構成及び動作について説明するために示す図であり、リターン通路２９のうちの絞り部３７及び弁部３５Ａが設けられた部分の断面図を示している。   FIGS. 6A and 6B are diagrams for explaining the configuration and operation of the valve portion 35A provided in the reducing agent supply apparatus according to the present embodiment. Sectional drawing of the part in which 37 and valve part 35A were provided is shown.

リターン通路２９は、その途中に絞り部３７を有している。また、リターン通路２９を構成する通路本体６０には、絞り部３７よりも第２の還元剤供給通路側に隣接してピストン摺動部６１が設けられている。ピストン摺動部６１の内部には、リターン通路２９内での液体還元剤の流れ方向に対して交差する方向に延在するピストン摺動孔６１ａが形成されている。   The return passage 29 has a throttle portion 37 in the middle thereof. Further, the passage main body 60 constituting the return passage 29 is provided with a piston sliding portion 61 adjacent to the second reducing agent supply passage side with respect to the throttle portion 37. Inside the piston sliding portion 61, a piston sliding hole 61a extending in a direction intersecting with the flow direction of the liquid reducing agent in the return passage 29 is formed.

ピストン摺動孔６１ａ内には、ピストンバルブ６５及びバルブスプリング６７が収容されている。ピストンバルブ６５は、ピストンバルブ６５は、その外周面においてピストン摺動孔６１ａの内周面と摺動しながら、ピストン摺動孔６１ａ内を移動可能になっている。また、バルブスプリング６７は、その一端がピストン摺動孔６１ａに対向する通路本体６０の内平面６０ａに当接するとともに他端がピストンバルブ６５に当接し、ピストンバルブ６５を内平面６０ａとは反対側に付勢する。   A piston valve 65 and a valve spring 67 are accommodated in the piston sliding hole 61a. The piston valve 65 is movable in the piston sliding hole 61a while sliding on the outer peripheral surface of the piston valve 65 with the inner peripheral surface of the piston sliding hole 61a. The valve spring 67 has one end abutting on the inner plane 60a of the passage body 60 facing the piston sliding hole 61a and the other end abutting on the piston valve 65. The piston valve 65 is opposite to the inner plane 60a. Energize to.

また、上述した絞り部３７の開口３７ａはピストン摺動孔６１ａに臨み、ピストンバルブ６５が内平面６０ａ側に移動した際には絞り部３７の開口３７ａがピストンバルブ６５によって閉じられ、リターン通路２９が遮断される。一方、ピストンバルブ６５が内平面６０ａとは反対側に移動した際には絞り部３７の開口３７ａが開かれ、リターン通路２９は開放される。本実施の形態においては、ピストンバルブ６５が遮断部材を構成し、バルブスプリング６７が弾性部材を構成している。   Further, the opening 37a of the throttle portion 37 described above faces the piston sliding hole 61a. When the piston valve 65 moves to the inner flat surface 60a side, the opening 37a of the throttle portion 37 is closed by the piston valve 65, and the return passage 29 Is cut off. On the other hand, when the piston valve 65 moves to the side opposite to the inner flat surface 60a, the opening 37a of the throttle portion 37 is opened and the return passage 29 is opened. In the present embodiment, the piston valve 65 constitutes a blocking member, and the valve spring 67 constitutes an elastic member.

また、ピストンバルブ６５における内平面６０ａ側の端部の一部には切欠き６５ａが形成されている。そのため、ピストンバルブ６５が内平面６０ａに当接した状態から、内平面６０ａとは反対側に戻る際に、ピストンバルブ６５が内平面６０ａに貼り付いて戻りにくくなることがないようになっている。   Further, a notch 65a is formed in a part of the end portion of the piston valve 65 on the inner plane 60a side. Therefore, when the piston valve 65 returns to the side opposite to the inner flat surface 60a from the state in which the piston valve 65 is in contact with the inner flat surface 60a, the piston valve 65 does not stick to the inner flat surface 60a and is difficult to return. .

このように構成された弁部３５Ａにおいて、内燃機関の始動後、すなわち、液体還元剤の噴射制御時においては、図６（ａ）に示すように、第２の還元剤供給通路側の圧力及びバルブピストン６７の付勢力によってピストンバルブ６５は内平面６０ａとは反対側に保持され、弁部３５Ａは開かれた状態となる。そのため、リターン通路２９は開放状態となり、液体還元剤はリターン通路２９を介して貯蔵タンクに戻される。   In the valve portion 35A configured as described above, after the internal combustion engine is started, that is, during the injection control of the liquid reducing agent, as shown in FIG. 6A, the pressure on the second reducing agent supply passage side and Due to the urging force of the valve piston 67, the piston valve 65 is held on the side opposite to the inner flat surface 60a, and the valve portion 35A is opened. Therefore, the return passage 29 is opened, and the liquid reducing agent is returned to the storage tank through the return passage 29.

内燃機関が停止して、液体還元剤の回収制御が開始されると、図６（ｂ）に示すように、第２の還元剤供給通路側に発生する負圧によって、ピストンバルブ６５がバルブスプリング６７の付勢力に抗して内平面６０ａ側に移動し、弁部３５Ａが閉じられた状態となる。そのため、リターン通路２９は遮断された状態となり、液体還元剤が効率的に吸い戻される。   When the internal combustion engine is stopped and the liquid reducing agent recovery control is started, as shown in FIG. 6 (b), the piston valve 65 is moved to the valve spring by the negative pressure generated on the second reducing agent supply passage side. It moves to the inner plane 60a against the urging force of 67, and the valve portion 35A is closed. As a result, the return passage 29 is blocked and the liquid reducing agent is efficiently sucked back.

その後、液体還元剤の回収制御が終了し、電動ポンプが停止すると、再び、図６（ａ）に示すように、ピストンバルブ６５がバルブスプリング６７の付勢力によって内平面６０ａとは反対側に移動し、リターン通路２９は開放状態となる。これにより、第２の還元剤供給通路内は速やかに負圧から正圧に復帰するため、電磁ポンプ内まで液体還元剤が逆流することがない。   Thereafter, when the recovery control of the liquid reducing agent is finished and the electric pump is stopped, the piston valve 65 is moved again to the opposite side to the inner plane 60a by the biasing force of the valve spring 67, as shown in FIG. Then, the return passage 29 is opened. Thus, the second reducing agent supply passage quickly returns from negative pressure to positive pressure, so that the liquid reducing agent does not flow back into the electromagnetic pump.

以上説明したように、本実施の形態にかかる還元剤供給装置の弁部３５Ａによっても、液体還元剤の回収制御時にリターン通路２９が遮断される一方、液体還元剤の回収制御終了後にリターン通路２９が開放されるために、回収制御時においては効率的に負圧が生じて液体還元剤を貯蔵タンク内に吸い戻すことができるとともに、回収制御終了後には第２の還元剤供給通路内が常に大気圧状態になって、貯蔵タンク内の液体還元剤が電磁ポンプ内に逆流することを防ぐことができる。したがって、電磁ポンプ内に残留した液体還元剤の凍結等による電磁ポンプの破損を低減することができる。   As described above, the return passage 29 is also shut off during the liquid reducing agent recovery control by the valve portion 35A of the reducing agent supply device according to the present embodiment, while the return passage 29 after the liquid reducing agent recovery control ends. Therefore, the negative pressure is efficiently generated during the recovery control, so that the liquid reducing agent can be sucked back into the storage tank, and the second reducing agent supply passage is always kept after the recovery control is completed. It is possible to prevent the liquid reducing agent in the storage tank from flowing back into the electromagnetic pump due to the atmospheric pressure state. Therefore, damage to the electromagnetic pump due to freezing of the liquid reducing agent remaining in the electromagnetic pump can be reduced.

また、本実施の形態にかかる還元剤供給装置においても、リターン通路２９のうちの弁部３５Ａよりも貯蔵タンク側の容量を、液体還元剤の回収制御を開始してから弁部３５Ａによってリターン通路２９が遮断されるまで、弁部３５Ａに液体還元剤が存在するように設定することとすれば、第２の還元剤供給通路内に発生する負圧によってリターン通路２９が確実に遮断され、液体還元剤の回収制御を効率的に行うことができる。   Also in the reducing agent supply apparatus according to the present embodiment, the capacity on the storage tank side of the valve portion 35A in the return passage 29 is set to the return passage by the valve portion 35A after the liquid reducing agent recovery control is started. If it is set so that the liquid reducing agent is present in the valve portion 35A until 29 is shut off, the return passage 29 is reliably shut off by the negative pressure generated in the second reducing agent supply passage, and the liquid is reduced. The recovery control of the reducing agent can be performed efficiently.

さらに、本実施の形態にかかる還元剤供給装置においても、弁部３５Ａにおける液体還元剤の流路が、貯蔵タンク側を下方にして配置することとすれば、液体還元剤が自重により落下しやすくなって、電動ポンプの停止後に弁部３５Ａに液体還元剤が残留することを防ぐこともできる。   Furthermore, also in the reducing agent supply apparatus according to the present embodiment, if the flow path of the liquid reducing agent in the valve portion 35A is arranged with the storage tank side down, the liquid reducing agent is likely to fall due to its own weight. Thus, it is possible to prevent the liquid reducing agent from remaining in the valve portion 35A after the electric pump is stopped.

［第３の実施の形態］
本発明の第３の実施の形態にかかる還元剤供給装置は、リターン通路２９に設けられる弁部３５Ｂの構成が第１及び第２の実施の形態にかかる還元剤供給装置に設けられた弁部とは異なっている。 [Third Embodiment]
In the reducing agent supply device according to the third embodiment of the present invention, the configuration of the valve portion 35B provided in the return passage 29 is the valve portion provided in the reducing agent supply device according to the first and second embodiments. Is different.

図７（ａ）〜（ｂ）は、本実施の形態にかかる還元剤供給装置に備えられた弁部３５Ｂの構成及び動作について説明するために示す図であり、リターン通路２９のうちの絞り部３７及び弁部３５Ｂが設けられた部分の断面図を示している。   FIGS. 7A and 7B are views for explaining the configuration and operation of the valve portion 35B provided in the reducing agent supply apparatus according to the present embodiment. Sectional drawing of the part in which 37 and the valve part 35B were provided is shown.

リターン通路２９は、その途中に絞り部３７を有している。また、リターン通路２９を構成する通路本体７０には制御室７３が設けられており、この制御室７３には第１の弁通路７１及び第２の弁通路７２が連通している。第１の弁通路７１は絞り部３７に連続して形成されている。すなわち、リターン通路２９は、絞り部３７、第１の弁通路７１、制御室７３、及び第２の弁通路７２を含むものとなっている。   The return passage 29 has a throttle portion 37 in the middle thereof. The passage body 70 constituting the return passage 29 is provided with a control chamber 73, and a first valve passage 71 and a second valve passage 72 communicate with the control chamber 73. The first valve passage 71 is formed continuously with the throttle portion 37. That is, the return passage 29 includes the throttle portion 37, the first valve passage 71, the control chamber 73, and the second valve passage 72.

制御室７３には弾性ゴム等の弾性材料で形成された弾性変位部材７５が収容され、弾性変位部材７５の周縁部分は蓋部７７によって固定されている。この弾性変位部材７５は変位部７５ａ及び弾性変形部７５ｂから構成され、弾性変形部７５ｂの伸縮によって変位部７５ａが進退動するものとなっている。弾性変形部７５ｂが縮んだ状態では変位部７５ａによって第１の弁通路７１及び第２の弁通路７２が塞がれることはなく、弾性変形部７５ｂが伸びた状態で変位部７５ａによって第１の弁通路７１及び第２の弁通路７２が塞がれる。本実施の形態においては、弾性変位部材７５の変位部７５ａが遮断部材を構成し、弾性変形部７５ｂが弾性部材を構成している。   An elastic displacement member 75 made of an elastic material such as elastic rubber is accommodated in the control chamber 73, and a peripheral portion of the elastic displacement member 75 is fixed by a lid 77. The elastic displacement member 75 includes a displacement portion 75a and an elastic deformation portion 75b, and the displacement portion 75a moves forward and backward by expansion and contraction of the elastic deformation portion 75b. When the elastic deformation portion 75b is contracted, the first valve passage 71 and the second valve passage 72 are not blocked by the displacement portion 75a, and the first displacement passage 75a is extended by the displacement portion 75a while the first deformation portion 75b is extended. The valve passage 71 and the second valve passage 72 are closed. In the present embodiment, the displacement portion 75a of the elastic displacement member 75 constitutes a blocking member, and the elastic deformation portion 75b constitutes an elastic member.

このように構成された弁部３５Ｂにおいて、内燃機関の始動後、すなわち、液体還元剤の噴射制御時においては、図７（ａ）に示すように、第２の還元剤供給通路側の圧力及び弾性変形部７５ｂの弾性力によって変位部７５ａが蓋部７７側に保持され、第１の弁通路７１及び第２の弁通路７２が開放される。一方、液体還元剤の回収制御時においては、図７（ｂ）に示すように、第２の還元剤供給通路側に発生する負圧によって、変位部７５ａが蓋部７７とは反対側に移動し、第１の弁通路７１及び第２の弁通路７２が閉じられる。さらに、液体還元剤の回収制御が終了し、電動ポンプが停止すると、再び、図７（ａ）に示すように、変位部７５ａが弾性変形部７５ｂの弾性力によって蓋部７７側に移動し、第１の弁通路７１及び第２の弁通路７２が開放される。   In the valve portion 35B configured as described above, after the internal combustion engine is started, that is, during the injection control of the liquid reducing agent, as shown in FIG. 7A, the pressure on the second reducing agent supply passage side and The displacement portion 75a is held on the lid portion 77 side by the elastic force of the elastic deformation portion 75b, and the first valve passage 71 and the second valve passage 72 are opened. On the other hand, at the time of liquid reductant recovery control, as shown in FIG. 7B, the displacement portion 75 a moves to the opposite side of the lid portion 77 due to the negative pressure generated on the second reductant supply passage side. Then, the first valve passage 71 and the second valve passage 72 are closed. Further, when the recovery control of the liquid reducing agent is finished and the electric pump is stopped, the displacement portion 75a is moved to the lid portion 77 side by the elastic force of the elastic deformation portion 75b again, as shown in FIG. The first valve passage 71 and the second valve passage 72 are opened.

以上説明したように、本実施の形態にかかる還元剤供給装置の弁部３５Ｂによっても、液体還元剤の回収制御時にリターン通路２９が遮断される一方、液体還元剤の回収制御終了後にリターン通路２９が開放されるために、回収制御時においては効率的に負圧が生じて液体還元剤を貯蔵タンク内に吸い戻すことができるとともに、回収制御終了後には第２の還元剤供給通路内が常に大気圧状態になって、貯蔵タンク内の液体還元剤が電磁ポンプ内に逆流することを防ぐことができる。したがって、電磁ポンプ内に残留した液体還元剤の凍結等による電磁ポンプの破損を低減することができる。   As described above, the return passage 29 is also blocked during the liquid reducing agent recovery control by the valve portion 35B of the reducing agent supply device according to the present embodiment, while the return passage 29 is terminated after the liquid reducing agent recovery control ends. Therefore, the negative pressure is efficiently generated during the recovery control, so that the liquid reducing agent can be sucked back into the storage tank, and the second reducing agent supply passage is always kept after the recovery control is completed. It is possible to prevent the liquid reducing agent in the storage tank from flowing back into the electromagnetic pump due to the atmospheric pressure state. Therefore, damage to the electromagnetic pump due to freezing of the liquid reducing agent remaining in the electromagnetic pump can be reduced.

また、本実施の形態にかかる還元剤供給装置においても、リターン通路２９のうちの弁部３５Ｂよりも貯蔵タンク側の容量を、液体還元剤の回収制御を開始してから弁部３５Ｂによってリターン通路２９が遮断されるまで、弁部３５Ｂに液体還元剤が存在するように設定することとすれば、第２の還元剤供給通路内に発生する負圧によってリターン通路２９が確実に遮断され、液体還元剤の回収制御を効率的に行うことができる。   Also in the reducing agent supply apparatus according to the present embodiment, the capacity on the storage tank side of the valve portion 35B in the return passage 29 is set to the return passage by the valve portion 35B after the liquid reducing agent recovery control is started. If it is determined that the liquid reducing agent is present in the valve portion 35B until 29 is shut off, the return passage 29 is reliably shut off by the negative pressure generated in the second reducing agent supply passage. The recovery control of the reducing agent can be performed efficiently.

さらに、本実施の形態にかかる還元剤供給装置においても、弁部３５Ｂにおける液体還元剤の流路が、貯蔵タンク側を下方にして配置することとすれば、液体還元剤が自重により落下しやすくなって、電動ポンプの停止後に弁部３５Ｂに液体還元剤が残留することを防ぐこともできる。   Furthermore, also in the reducing agent supply device according to the present embodiment, if the flow path of the liquid reducing agent in the valve portion 35B is arranged with the storage tank side downward, the liquid reducing agent is likely to fall due to its own weight. Thus, it is possible to prevent the liquid reducing agent from remaining in the valve portion 35B after the electric pump is stopped.

なお、本実施の形態においては、弾性変位部材７５が弾性ゴム等の弾性材料で構成することとしているが、金属ダイヤフラム等を用いた構成とすることもできる。   In the present embodiment, the elastic displacement member 75 is made of an elastic material such as elastic rubber. However, a configuration using a metal diaphragm or the like may be used.

［その他の実施の形態］
以上説明した第１〜第３の実施の形態にかかる還元剤供給装置は、本発明の一態様を示すものであってこの発明を限定するものではなく、これらの実施の形態は本発明の範囲内で任意に変更することが可能である。特に、弁部の構成については、第２の還元剤供給通路内の圧力が正圧の状態及び電動ポンプの停止状態でリターン通路を開放する一方、第２の還元剤供給通路内の圧力が負圧の状態となったときにリターン通路を遮断する機能を有するものであれば、特に限定されるものではない。 [Other embodiments]
The reducing agent supply apparatus according to the first to third embodiments described above shows one aspect of the present invention and does not limit the present invention. These embodiments are within the scope of the present invention. It is possible to change arbitrarily within. In particular, regarding the configuration of the valve portion, the pressure in the second reducing agent supply passage is opened while the pressure in the second reducing agent supply passage is positive and the electric pump is stopped, while the pressure in the second reducing agent supply passage is negative. If it has a function which interrupts | blocks a return path when it will be in the state of a pressure, it will not specifically limit.

３：排気通路、１０：排気浄化装置、１３：還元触媒、２０：還元剤供給装置、２１：貯蔵タンク、２３：電動ポンプ、２３ａ：入り口側、２３ｂ：出口側、２５：電磁噴射弁、２７：第１の還元剤供給通路、２８：第２の還元剤供給通路、２９：リターン通路、３０：ポンプユニット、３１：圧力センサ、３３：流路切換弁、３５・３５Ａ・３５Ｂ：弁部、３７：絞り部、３７ａ：開口、４０：電子制御装置（ＥＣＵ）、５０：通路本体、５１：第１の係止突部、５１ａ：開口部、５３：第２の係止突部、５３ａ：開口部、５５：ピストンバルブ、５５Ａ：通過孔、５５Ａａ：大径部、５５Ａｂ：小径部、５５Ｂ：シート部、５７：バルブスプリング、５９：ロッド部、６０：通路本体、６０ａ：内平面、６１：ピストン摺動部、６１ａ：ピストン摺動孔、６５：ピストンバルブ、６５ａ：切欠き、６７：バルブスプリング、７０：通路本体、７１：第１の弁通路、７２：第２の弁通路、７３：制御室、７５：弾性変位部材、７５ａ：変位部、７５ｂ：弾性変形部、７７：蓋部 3: exhaust passage, 10: exhaust purification device, 13: reduction catalyst, 20: reducing agent supply device, 21: storage tank, 23: electric pump, 23a: inlet side, 23b: outlet side, 25: electromagnetic injection valve, 27 : First reducing agent supply passage, 28: second reducing agent supply passage, 29: return passage, 30: pump unit, 31: pressure sensor, 33: flow path switching valve, 35 / 35A / 35B: valve section, 37: throttle part, 37a: opening, 40: electronic control unit (ECU), 50: passage main body, 51: first locking projection, 51a: opening, 53: second locking projection, 53a: Opening part, 55: Piston valve, 55A: Passing hole, 55Aa: Large diameter part, 55Ab: Small diameter part, 55B: Seat part, 57: Valve spring, 59: Rod part, 60: Passage body, 60a: Inner plane, 61 : Piston sliding part, 61a: Stone sliding hole, 65: piston valve, 65a: notch, 67: valve spring, 70: passage body, 71: first valve passage, 72: second valve passage, 73: control chamber, 75: elastic displacement Member, 75a: displacement part, 75b: elastic deformation part, 77: lid part

Claims (3)

貯蔵タンク内の液体還元剤を吸い上げて圧送するポンプと、前記ポンプにより圧送される前記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部と、前記ポンプと前記還元剤噴射部とを接続する還元剤供給通路と、前記還元剤供給通路から分岐して前記ポンプにより圧送される前記液体還元剤の一部を前記貯蔵タンクに戻すためのリターン通路と、を備え、
前記内燃機関の運転時には前記ポンプにより前記液体還元剤を前記還元剤噴射部側に圧送し、前記内燃機関の停止時には前記ポンプにより前記液体還元剤を前記貯蔵タンクに回収する制御が実行されるように構成された還元剤供給装置において、
前記リターン通路の途中に、流路面積を小さくした絞り部を備えるとともに、
前記絞り部よりも前記還元剤供給通路側に、前記液体還元剤の回収制御時には前記還元剤供給通路及び前記リターン通路内の圧力の低下に伴い前記リターン通路を遮断する一方、前記液体還元剤の回収制御終了後には前記リターン通路を開放するように構成された弁部を備えることを特徴とする還元剤供給装置。 A pump that sucks up and pumps the liquid reducing agent in the storage tank; a reducing agent injection unit that injects the liquid reducing agent pumped by the pump into an exhaust passage of the internal combustion engine; and the pump and the reducing agent injection unit. A reducing agent supply passage to be connected; and a return passage for returning a part of the liquid reducing agent branched from the reducing agent supply passage and pumped by the pump to the storage tank,
Control is performed so that the liquid reducing agent is pumped to the reducing agent injection unit by the pump during operation of the internal combustion engine, and the liquid reducing agent is recovered to the storage tank by the pump when the internal combustion engine is stopped. In the reducing agent supply apparatus configured in
In the middle of the return passage, with a throttle portion with a reduced flow path area,
When the liquid reducing agent is controlled to be recovered, the return passage is shut off as the pressure in the reducing agent supply passage and the return passage decreases, while the liquid reducing agent A reducing agent supply apparatus comprising: a valve portion configured to open the return passage after completion of the recovery control. 前記弁部は、前記リターン通路を遮断する遮断部材と、前記リターン通路を開放する方向に前記遮断部材を常時付勢する弾性部材と、を備え、前記圧力の低下時に発生する負圧によって、前記弾性部材の付勢力に抗して前記遮断部材が移動し、前記リターン通路を遮断するように構成されてな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 valve portion includes a blocking member that blocks the return passage, and an elastic member that constantly biases the blocking member in a direction to open the return passage, and the negative pressure generated when the pressure is reduced, The reducing agent supply device according to claim 1, wherein the blocking member moves against an urging force of an elastic member to block the return passage. 前記リターン通路のうちの前記弁部よりも前記貯蔵タンク側の容量が、前記液体還元剤の回収を開始してから前記弁部によって前記リターン通路が遮断されるまで、前記弁部に前記液体還元剤が存在するように設定されてなることを特徴とする請求項１又は２に記載の還元剤供給装置。   The capacity of the return tank on the side of the storage tank relative to the valve section starts from the recovery of the liquid reducing agent until the return path is blocked by the valve section until the liquid reduction is performed on the valve section. 3. The reducing agent supply device according to claim 1, wherein the reducing agent supply device is set so that the agent is present.
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JP2020067055A (en) * 2018-10-26 2020-04-30 ロベルト・ボッシュ・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツングＲｏｂｅｒｔ Ｂｏｓｃｈ Ｇｍｂｈ Reducer supply device
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