CN112648053A - Method for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst - Google Patents

Method for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst Download PDF

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Publication number
CN112648053A
CN112648053A CN202011070648.8A CN202011070648A CN112648053A CN 112648053 A CN112648053 A CN 112648053A CN 202011070648 A CN202011070648 A CN 202011070648A CN 112648053 A CN112648053 A CN 112648053A
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CN
China
Prior art keywords
metering
reducing agent
delivery
agent solution
scr catalyst
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Pending
Application number
CN202011070648.8A
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Chinese (zh)
Inventor
T·赫夫肯
E·布斯
M·谢纳
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Robert Bosch GmbH
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Robert Bosch GmbH
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Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of CN112648053A publication Critical patent/CN112648053A/en
Pending legal-status Critical Current

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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
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • 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]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • 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
    • 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
    • F01N2610/1433—Pumps
    • 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
    • F01N2610/1433—Pumps
    • F01N2610/144—Control thereof
    • 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
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • 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
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • F01N2610/146—Control thereof, e.g. control of injectors or injection valves
    • 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
    • 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
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

Method for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst. The invention relates to a method for operating a delivery and metering system for a reducing agent solution of at least one SCR catalyst of an internal combustion engine, wherein the delivery and metering system comprises: at least one feed pump, at least one return pump, a hydraulic supply line and a plurality of metering valves connected to the hydraulic supply line. After the internal combustion engine is shut down, reducing agent is sucked back (82) at least from the part of the delivery and metering system during the closing of the metering valve. Subsequently, all metering valves are opened (84) simultaneously.

Description

Method for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst
Technical Field
The invention relates to a method for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst of an internal combustion engine. The invention also relates to: a computer program implementing each step of the method; and a machine-readable storage medium storing the computer program. Finally, the invention relates to an electronic control device which is set up to carry out the method.
Background
In order to reduce the proportion of nitrogen oxides in the exhaust gas of an internal combustion engine, in particular a diesel engine, it is known to arrange an SCR catalyst (selective catalytic reduction) in the exhaust gas line of the exhaust gas. The SCR catalyst reduces nitrogen oxides contained in the exhaust gas to nitrogen gas in the presence of ammonia as a reducing agent. To supply ammonia, a reducing agent solution is metered (eindosiert) into the exhaust gas line upstream of the SCR catalyst. Generally, urea solutions (urea-water solutions (Harnstoff-Wasser-L) are used for this purpose, HWL), which contain urea as ammonia-releasing agent. A HWL of 32.5 percent can be obtained under the name of AdBlue on the market. The 32.5% HWL was frozen at a temperature of-11.5 ℃.
When the internal combustion engine is shut down, the SCR metering system is emptied or ventilated by back suction in order to protect the metering valve and the pressure line from the ice pressure during freezing. In metering operation, the system is under pressure due to the operation of the delivery pump. After the internal combustion engine is shut down, the system pressure is reduced by stopping the feed pump and, if necessary, opening a pressure relief valve or a return pump. By emptying with the aid of the return pump when the metering valve is closed, a negative pressure is generated in the system. The metering valve is then opened with continuous emptying of the system. Through this, air is suddenly sucked in at the metering valve. The evacuation process continues until the negative pressure in the system has stabilized.
DE 102011081628 a1 describes a metering system for a liquid reducing agent, which can be emptied by means of a return pump.
Disclosure of Invention
The method is used for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst of an internal combustion engine, wherein the system comprises: at least one feed pump, at least one return pump, a hydraulic supply line and a plurality of metering valves, in particular two metering valves, which are connected to the hydraulic supply line. The feed pump and the return pump can also be realized by a single pump, which can be operated with different feed directions. Such a metering system can be provided, for example, for an SCR catalyst system having two SCR catalysts, wherein a first metering valve is arranged in the exhaust gas line upstream of the first SCR catalyst and a second metering system is arranged between the SCR catalysts.
After the internal combustion engine is shut down, the reducing agent is sucked back at least from the part of the delivery and metering system during the closing of the metering valve. Subsequently, all metering valves are opened simultaneously.
As a result of the negative pressure being built up before the metering valves are opened, unintentional metering of minute amounts of reducing agent solution during the suck-back process can be reduced. The metering valves are opened only when a negative pressure is present at the metering valves. In addition, the emptying process of the metering valves is carried out very abruptly in this way. This draining is performed dynamically better than starting the return flow if the metering valve is already open, since less reducing agent solution remains in the metering valve. By opening all metering valves simultaneously, it is avoided that a drop in the negative pressure already occurs due to the premature opening of one metering valve, so that the emptying process of the other metering valves is delayed.
Preferably, the metering valves are opened only when the negative pressure in the delivery and metering system is at least 5000 pascals (Pascal). It is particularly preferred that the metering valves are opened only when the underpressure is at least 15000 pascal. Thereby ensuring that: the emptying process of these metering valves takes place suddenly, so that the reducing agent solution cannot unintentionally enter the exhaust gas line. In this case, the negative pressure is not to be understood as an absolute value of the pressure but as a relative negative pressure with respect to the ambient pressure.
If no pressure sensor is present to measure the pressure in the hydraulic supply line, it is instead preferable to open the metering valves after a predeterminable period of time. Preferably, the period of time is in the range of 5 seconds to 10 seconds.
Preferably, the back-suction of the reducing agent is continued after the metering valves are opened. Thereby, further volumes of reducing agent solution can be withdrawn from the part of the hydraulic supply line leading to the metering valves. This results in an increased robustness with respect to the transfer of the reducing agent solution in the hydraulic supply line, which may cause ice pressure at low temperatures.
Preferably, the suck-back with the metering valve open is carried out for a predeterminable period of time. By this, too much air is prevented from entering the hydraulic supply line. The predeterminable time period is preferably at most 2 seconds, particularly preferably at most 1 second.
The computer program is set up as: in particular, each step of the method is performed when the computer program runs on a computing device or on an electronic control device. The computer program enables implementation of the different embodiments of the method on an electronic control device without structural changes in this respect. To this end, the computer program is stored on the machine-readable storage medium.
The electronic control unit is obtained by uploading (Aufspielen) the computer program onto a conventional electronic control unit, which is set up to operate a delivery and metering system for the reducing agent solution of the at least one SCR catalyst by means of the method.
Drawings
Embodiments of the invention are illustrated in the drawings and are further described in the following description.
Fig. 1 schematically shows components of a delivery and metering system for a reducing agent solution for an SCR catalyst, which can be operated by means of an embodiment of the method according to the invention.
Fig. 2 shows a flow chart of an embodiment of the method according to the invention.
Detailed Description
Fig. 1 schematically shows the components of a delivery and metering system with a delivery pump 10, a hydraulic supply line (pressure line) 20 and two metering valves 31, 32. The delivery pump 10 is assigned a suction valve 11 and a pressure valve 12, wherein a throttle 13 is present upstream of the pressure valve 12. Upstream of the suction valve 11 there is a filter 14. In the region of the supply line 20 there is a pressure sensor 21 for measuring the pressure p and a pulsation damper 22. By means of the delivery pump 10, the liquid reducing agent solution is drawn off from a supply unit (storage tank) 60 via a filter 61 and is conveyed via a T-branch in the hydraulic supply line 20 to the two metering valves 31, 32 and metered there as required into an exhaust gas line, not shown here. In order to suck back the freezable reducing agent solution from the ice pressure- sensitive metering valves 31, 32 and, if appropriate, from the supply line 20, a suck-back pump unit 40 is provided, which is arranged in a separate suck-back path 41 of the system with a further filter 48. The suck-back pump unit 40 comprises a conventional suck-back pump 42, which is assigned a suction valve 43 and a pressure valve 44. In parallel with the pressure valve 44 there is a bypass line 45 with a throttle 46. In the region of the intake zone of the feed pump 10 and downstream of the suck-back pump 42 in the return path of the system, there is an ice pressure damper 15 or 47, respectively. The different elements of the delivery and metering system are combined in a delivery module 50, wherein the delivery module 50 also comprises a suck-back pump unit 40.
After the internal combustion engine has been shut down, the reducing agent solution is fed back into the storage tank 60 by means of the suckback pump 42 from the metering valves 31, 32 and, if necessary, also partially or completely from the supply line 20 via the suckback path 41. The feed pump 10, the return pump 42 and the metering valves 31, 32 are actuated by an electronic control device 70.
Fig. 2 shows the flow of the method in a first exemplary embodiment of the invention. After the start 80 of the method, a first check 81 is performed: whether the internal combustion engine has stopped. If this shutdown occurs, the feed pump 10 is switched off and the suck-back pump 42 is switched on and then switched on in order to start the suck-back 82 of the reducing agent solution. In this case, the metering valves 31, 32 are closed. As soon as the second check 83 has concluded that the negative pressure p measured by means of the pressure sensor 21 has fallen below 1500 pascals, the two metering valves 31, 32 are opened 84 at the same time. After the metering valves are closed again, the suck-back is continued for a period of one second, wherein the metering valves 31, 32 are opened simultaneously or successively, so that additional volume is removed from the supply line 20 and the suck-back path 41. The reflux pump is then turned off 85 and the method ends 86.
The second embodiment of the present invention differs from the first embodiment in that: in the case of the second check 83, it is not checked whether the negative pressure p measured by means of the pressure sensor 21 has dropped below 1500 pascals. Instead, it is checked whether a period of 7 seconds has elapsed since the return pump 42 was turned on.

Claims (10)

1. Method for operating a delivery and metering system for a reducing agent solution of at least one SCR catalyst of an internal combustion engine, wherein the delivery and metering system comprises: at least one delivery pump (10), at least one suction pump (42), a hydraulic supply line (20) and a plurality of metering valves (31, 32) connected to the hydraulic supply line (20), characterized in that after shutdown of the internal combustion engine, reducing agent is sucked back (82) at least from a part of the delivery and metering system during shut-down of the metering valves (31, 32) and all metering valves (31, 32) are then opened (84) simultaneously.
2. Method according to claim 1, characterized in that the metering valve (31, 32) is only opened when the negative pressure (p) in the delivery and metering system is at least 5000 pascals.
3. Method according to claim 1, characterized in that the metering valve is opened after a predeterminable first period of time.
4. The method of claim 2, wherein the first period of time is in a range of 5 seconds to 10 seconds.
5. The method according to any one of claims 1 to 4, characterized in that after opening the metering valve (31, 32) the back-suction (82) of the reducing agent is continued.
6. Method according to claim 5, characterized in that the suck-back (82) takes place for a predeterminable second period of time at the maximum with the metering valve open.
7. The method of claim 6, wherein the second period of time is up to 2 seconds.
8. Computer program set up to perform each step of the method according to any one of claims 1 to 7.
9. Machine readable storage medium having stored thereon a computer program according to claim 8.
10. Electronic control device (70) which is set up to operate a system for delivering and metering a reducing agent solution to at least one SCR catalyst by means of a method according to one of claims 1 to 7.
CN202011070648.8A 2019-10-11 2020-10-09 Method for operating a system for delivering and metering a reducing agent solution to at least one SCR catalyst Pending CN112648053A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102019215603.7A DE102019215603A1 (en) 2019-10-11 2019-10-11 Method for operating a delivery and metering system for the reducing agent solution of at least one SCR catalytic converter
DE102019215603.7 2019-10-11

Publications (1)

Publication Number Publication Date
CN112648053A true CN112648053A (en) 2021-04-13

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CN (1) CN112648053A (en)
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101084053A (en) * 2004-11-10 2007-12-05 罗伯特·博世有限公司 Dosing system and method for the operation of a dosing system
CN102022168A (en) * 2009-09-14 2011-04-20 罗伯特.博世有限公司 Method of monitoring function of selective catalytic reaction (SCR) catalyst
CN103975137A (en) * 2011-12-12 2014-08-06 罗伯特·博世有限公司 Dosing arrangement for a liquid exhaust gas after-treatment medium and dosing method
CN107842488A (en) * 2016-09-19 2018-03-27 罗伯特·博世有限公司 The method for running the stroke magnet armature pump for returning to conveying in empty stage
CN108625955A (en) * 2017-03-24 2018-10-09 罗伯特·博世有限公司 For controlling tool, there are two the methods of the SCR system of metering valve

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010031660A1 (en) * 2010-07-22 2012-01-26 Robert Bosch Gmbh Method for operating dosing system for selective catalytic reduction catalyst converter of combustion engine of e.g. car, involves opening relief valve and dosing module after termination of dosing process
DE102012212564A1 (en) * 2012-07-18 2014-01-23 Robert Bosch Gmbh Method for operating conveyor and dosing system, involves mixing medium with return flow path by feed pump during the return conveyance of medium from the pressure-side portion of the system out of the medium reservoir
DE102016210262A1 (en) * 2016-06-10 2017-12-14 Robert Bosch Gmbh A method of emptying a reductant delivery system of an SCR catalyst
DE102016218497A1 (en) * 2016-09-27 2018-03-29 Robert Bosch Gmbh Reductant supply system for exhaust aftertreatment

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101084053A (en) * 2004-11-10 2007-12-05 罗伯特·博世有限公司 Dosing system and method for the operation of a dosing system
CN102022168A (en) * 2009-09-14 2011-04-20 罗伯特.博世有限公司 Method of monitoring function of selective catalytic reaction (SCR) catalyst
CN103975137A (en) * 2011-12-12 2014-08-06 罗伯特·博世有限公司 Dosing arrangement for a liquid exhaust gas after-treatment medium and dosing method
CN107842488A (en) * 2016-09-19 2018-03-27 罗伯特·博世有限公司 The method for running the stroke magnet armature pump for returning to conveying in empty stage
CN108625955A (en) * 2017-03-24 2018-10-09 罗伯特·博世有限公司 For controlling tool, there are two the methods of the SCR system of metering valve

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DE102019215603A1 (en) 2021-04-15

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