CN102022168A - Method of monitoring function of selective catalytic reaction (SCR) catalyst - Google Patents

Method of monitoring function of selective catalytic reaction (SCR) catalyst Download PDF

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Publication number
CN102022168A
CN102022168A CN2010102839747A CN201010283974A CN102022168A CN 102022168 A CN102022168 A CN 102022168A CN 2010102839747 A CN2010102839747 A CN 2010102839747A CN 201010283974 A CN201010283974 A CN 201010283974A CN 102022168 A CN102022168 A CN 102022168A
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CN
China
Prior art keywords
scr catalyst
catalyst system
valve
metering valve
resorption
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Granted
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CN2010102839747A
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Chinese (zh)
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CN102022168B (en
Inventor
D·西兰
H·克莱因内克特
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10Exhaust 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
    • F01N3/18Exhaust 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
    • F01N3/20Exhaust 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
    • F01N3/2066Selective catalytic reduction [SCR]
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/002Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/05Systems for adding substances into exhaust
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/02Adding substances to exhaust gases the substance being ammonia or urea
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/14Arrangements for the supply of substances, e.g. conduits
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/14Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1466Means for venting air out of conduits or tanks
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06Parameters used for exhaust control or diagnosing
    • F01N2900/18Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806Properties of reducing agent or dosing system
    • F01N2900/1808Pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06Parameters used for exhaust control or diagnosing
    • F01N2900/18Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806Properties of reducing agent or dosing system
    • F01N2900/1822Pump parameters
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/40Engine 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

The invention relates to a method of monitoring the function of a selective catalytic reaction (SCR) catalyst, which is the method of monitoring the function of the SCR catalyst being as the waste gas aftertreatment system of an internal combustion engine. The SCR catalyst comprises at least one feed pump (5), at least one manifold valve (9), at least one metering valve (3) and at least one pressure sensor (10). In the sucking-back module of a SCR catalyst system (1), the negative pressure establishment in the SCR catalyst system can be observed by means of at least one measuring value of the pressure sensor (10). When the at least one measuring value deviates an expected reference value, the mistake of the function of the SCR catalyst system can be concluded.

Description

The method of the function of monitoring SCR catalyst system
Technical field
The present invention relates to a kind of method of function of the SCR of monitoring catalyst system, this SCR catalyst system is the exhausted gas post-processing system of internal-combustion engine.In addition, the invention still further relates to a kind of computer program and a kind of computer program of carrying out the method.
Background technique
The method and apparatus that is used for especially driving internal-combustion engine in Motor Vehicle is known, SCR catalyst system (Selective Catalytic Reduction) is arranged in its waste gas zone, and it makes the nitrogen oxide (Nox) that is contained in the engine exhaust gas be reduced into nitrogen under the situation that reducing agent participates in.Therefore, can obviously reduce nitrogen oxides from exhaust gas content.Reduction process needs ammonia (NH 3), this ammonia is sneaked in the waste gas.Therefore can use NH 3Or NH 3The reactant that decomposes is as reactant.Usually, use moisture urea liquid (aqueous solution of urea), it sprayed in the waste gas system by measuring apparatus before the SCR catalyst system for this reason, and this measuring apparatus also has metering valve.Form NH in the solution thus 3, this NH 3Play reducing agent.For the storage uncorrectable cellulose solution, be provided with reducing agent jar or aqueous solution of urea jar.
From then on jar the reducing agent jar has been equipped with so-called pumping tube usually, is used for an aqueous solution of urea to extract out in.For the transport urea aqueous solution or medium, be provided with pump, this pump flows to measuring apparatus to medium (being aqueous solution of urea) by pipe-line system, so aqueous solution of urea can spray under pressure in the waste gas system by metering valve (for example injection valve of electromagnetism).The pipeline of SCR catalyst system can be provided with like this, promptly sets so-called resorption pattern by the switching of multi-way valve (for example No. 4/2 valve), and this resorption pattern can be extracted medium out from pipeline.Described resorption is necessary, because aqueous solution of urea can freeze in (especially under-11 ℃ or lower temperature) under the low ambient temperature.Medium freezes in pipeline may damage pipe-line system.Therefore stipulate that medium can be led once more and be got back in the reducing agent jar.In order to set the resorption pattern, need correspondingly control (control especially electrically) No. 4/2 valve, and control preferably has been equipped with the transfer pump of integrated restrictor check valve.
Diverse location in the SCR catalyst system all functional fault may occur.For example break down at (especially on multi-way valve or metering valve) on the valve.In addition, also may influence or disturb the function of transfer pump.In addition, pipe-line system also may blow-by or appearance leakage.This point is possibility especially, because metering valve can be separated by several meters long pipeline highway section and transfer pump.These pipeline pressure-loaded, the wherein about usually 5bar of pressure.All pipelines (for example plastic flexible pipe) and the link that usually also is made of plastics all may be because damage and blow-by appear in aging, setup error or other damage.Thus, this may reveal environmentally harmful aqueous solution of urea on the one hand.On the other hand, can not guarantee to carry out normal exhaust after-treatment thus again.
Usually, the sealing of (especially in the pipe-line system) detects by this way in the SCR catalyst system, and promptly this system is by running transfer pump pressure-loaded.And then, the motor of the pump that stops is also observed, and how pressure descends apace.If pressure can not be kept enough and/or it sets up the overlong time that continues up to pressure, can conclude that then this system is packing less.Therefore, for example the open source literature DE 102006013293A1 of German has described a kind of method, be used for pressure in the diagnostic reaction agent metering system, reactant is placed on the pressure source in the method, and the reactant pressure and the threshold value that record are compared, and when surpassing threshold value, send error signal.
This controlling method has different shortcomings.If in this system, have blow-by or leakage really, then because the foundation of pressure can be discharged how environmentally harmful aqueous solution of urea.In addition, can only determine very significantly to reveal by this controlling method.This is that this system has throttle orifice usually, and it is essential, so that can guarantee the pressure regulatory function.Even other system seals, still can reveal pressure by this throttle orifice, therefore can not provide qualitatively at all and analyze.Therefore, can only determine the leakage of highly significant.
Summary of the invention
By the objective of the invention is, get rid of the described shortcoming of the known sealing detection of SCR catalyst system, and a kind of method of better monitoring SCR catalyst system is provided.This purpose is achieved by the described method of a kind of content as claimed in claim 1.Draw the preferable configuration of the method by dependent claims.
Be provided with to such an extent that be used for monitoring the function of SCR catalyst system by method of the present invention, this SCR catalyst system is the exhausted gas post-processing system of internal-combustion engine.The SCR catalyst system also comprises at least one transfer pump, at least one multi-way valve (especially No. 4/2 valve) and at least one metering valve.This transfer pump is provided with to such an extent that be used for the helping a small child urinate by holding his legs apart plain aqueous solution or medium are exported from the reducing agent jar.Then, this medium can spray under pressure in the waste gas system by metering valve.This multi-way valve (especially No. 4/2 valve) is provided with to such an extent that be used for switching to the resorption pattern from suction mode, so medium can be carried to return and lead and get back in the reducing agent jar from pipe-line system.The SCR catalyst system also has at least one pressure transducer, and it preferably is arranged in the pipe-line system in the downstream of transfer pump.Be characterised in that by method of the present invention, in the resorption pattern of SCR catalyst system, set up by the negative pressure that at least one measured value of pressure transducer is observed in the SCR catalyst system.When the reference value of described at least one measured value and expection had deviation, the reference value of this expection was represented normally functioning system, and then the deducibility function that goes out the SCR catalyst system breaks down.Basis by method of the present invention also is, sets up negative pressure in normally functioning SCR catalyst system in the resorption pattern.If this negative pressure can not or can not be set up and/or maintenance with the degree of expection, then deducibility has the fault of existence.Being also advantageous in that of the method, this SCR catalyst system have been ready to implement the resorption pattern usually, are used for medium is sent back to the reducing agent jar from pipeline.Utilize this resorption pattern that has been provided with by method of the present invention, so that monitoring or diagnosis SCR catalyst system.For this reason, need other element be installed in the SCR catalyst system, because can employ the element that has existed in case of necessity yet.
In order to implement by method of the present invention, and in order to set the resorption pattern, preferably like this multi-way valve is controlled, promptly medium is released from the pipeline of SCR catalyst system when the control transfer pump.The negative pressure that analysis is set up in this pattern in pipe-line system.For this reason, detect the numerical value of surveying of this or these pressure transducer, and the contrast reference value is analyzed.The numerical value of this reference value representative pressure sensor, this numerical value may detect in the normally functioning SCR catalyst system.If numerical value and this or these reference value of these or this actual measurement have deviation, then deducibility goes out, and the functional of SCR catalyst system can not or can not intactly be brought into play at least.
In especially preferred embodiment of the present invention, before the resorption pattern or during at least temporarily close described at least one metering valve.When metering valve cuts out, in the pipe-line system of SCR catalyst system, set up negative pressure with especially tangible method.By in the structural scheme of method of the present invention, can obtain especially good or tangible signal.
Preferably by the sealing that detects the SCR catalyst system by method of the present invention.If negative pressure can not be set up in the resorption pattern or can not fully set up, or set up slowlyer than reference value, then deducibility goes out, and this system is packing less or exists leakage.
By in another preferred embodiment of method of the present invention,, detect the functional of described at least one metering valve by observing the negative pressure in the take-back model.This point can be carried out like this, promptly before the resorption pattern or during close metering valve, therefore can set up negative pressure.When opening metering valve for the realization test purpose, negative pressure should suddenly reduce.If can not confirm the variation in pressure of expecting, then deducibility goes out, and metering valve does not normally work or blocks with sealing.Also can determine the metering valve that blocks by the present invention with opening.For this reason, when opening, sets up by metering valve negative pressure.Then control metering valve with throttle down, this should be able to strengthen negative pressure, as long as metering valve is normally functioning.Can and observe the switching capability that variation in pressure is come the tester metered valve by the repeated control metering valve.
By in another preferred embodiment of the present invention, detect the functional of described at least one transfer pump.If set up negative pressure when implementing the resorption pattern, then to go out transfer pump be normally functioning in deducibility.If do not set up negative pressure, then for example the integrated restrictor check valve on safety check or the pump is packing less, or pump has fault in others.
In addition, preferably also detect the functional of described at least one multi-way valve (especially No. 4/2 valve).If this multi-way valve function is undesired, then it has for example blocked, and can not switch to the resorption pattern when the control multi-way valve.Pipe-line system is stayed under the pressure operated pattern in the case, therefore can not set up negative pressure.
For example can detect the element of SCR system as follows by the present invention ground: at first when metering valve cuts out, start the resorption pattern.In the multi-way valve function just often, carrying electric motors function just often and just often, or when metering valve cuts out,, can recognize the foundation of negative pressure by the increase that obviously can survey of negative pressure in the metering valve function.If open metering valve, then pressure should suddenly reduce, or negative pressure should reduce.If observe these expected results, then deducibility goes out, and the required element of all of resorption pattern all is normally functioning.
By in the especially preferred structural scheme of method of the present invention, detect the normal variation of resorption process.Usually, by in the specific application time, this system being transferred in the resorption pattern, medium resorption from the pipe-line system of SCR catalyst system is come out.Need not to detect medium and whether from pipe-line system, lead back practically or be withdrawn in the reducing agent jar, just can realize this resorption.Need not consider different possible error reasons at this, for example multi-way valve has blocked, transfer pump has fault, system's blow-by etc.For example, if this system is packing less, if or metering valve made dirty, so a spot of air may suck, then may prolong medium greatly and from pipe-line system, take the required time fully away.By the present invention, the variation of resorption process is monitored in the variation of negative pressure that can be by overview setup, because the negative pressure of setting up in pipeline under the negative pressure of setting up in pipeline under the situation of existing medium and situation at air is different.
The present invention also comprises a kind of computer program, if this computer program moves on the calculating equipment of internal-combustion engine or controller, then it implement described method institute in steps.At last, the present invention also comprises a kind of computer program with program-code, and this computer program is stored on the machine-readable carrier containing, if this program is moved on calculating equipment or controller, implements described method.By this computer program, can monitor the SCR catalyst system in very favorable mode.Especially can be by the foundation of negative pressure in the pipe-line system of SCR catalyst system, whether function is normal to determine the different elements of SCR catalyst system.In addition, but by this computer program sealing of supervisory system also.The special advantage of computer program is that it can be applicable in the existing Motor Vehicle, need not to install additional in the SCR catalyst system other element.Only need be complementary, promptly on the controller of internal-combustion engine, turn round and realize by being stored in computer program on the computer program with analysis software.
Description of drawings
In conjunction with the accompanying drawings, from embodiment's following description, draw other advantage of the present invention and feature.Single feature can be distinguished individually or the realization of combination with one another ground at this.
Fig. 1 shows the different elements of SCR catalyst system (prior art) in the diagram;
Fig. 2 shows the MEDIA FLOW in the resorption pattern in the SCR catalyst system in the diagram;
Fig. 3 shows the oscillogram of pressure transducer voltage, and this is to produce when the preferable configuration scheme of implementing by method of the present invention;
Fig. 4 shows another oscillogram of pressure transducer voltage, and this is to produce when the preferable configuration scheme of implementing by method of the present invention.
Embodiment
Fig. 1 shows in the diagram from the different elements of the known SCR catalyst system 1 of prior art.This SCR catalyst system 1 be provided be used for internally firing the machine (not shown) waste gas carry out reprocessing.For this reason, the reducing agent of fluid (it is stored in the reducing agent jar 2) sprays under pressure in the waste gas system by metering valve 3.Metering valve 3 for example refers to the injection valve of electromagnetism, and it is controlled by controller 4.This reducing agent is exported from reducing agent jar 2 by pumping tube 6 by pump 5 (it has integrated restrictor check valve), and delivers to metering valve 3 by pipe-line system under pressure.In order to regulate pressure, be provided with throttle orifice 7, its following current is arranged in the reducing agent jar 2 before reflow pipe 8.In order to connect MEDIA FLOW, be provided with No. 4/2 valve 9, it is the same with pump 5 controls by controller 4.For monitor force, in the pipeline between No. 4/2 valve 9 and metering valve 3 pressure transducer 10 is set.In this embodiment, transfer pump 5, No. 4/2 valve 9 and pressure transducer 10 fit together in shell 11, constitute so-called conveyor module.Pipeline length between conveyor module 11 and metering valve 3 can for example reach 4m.Usually the pressure that has about 5bar in the pressure piping between pump 5 and metering valve 3.The quick connector that required different hose connectors normally are made of plastics.Therefore these flexible pipes also are made of plastics usually, because aging, setup error or damage and may cause blow-by or leakage.
By the present invention, attempt in the resorption pattern of SCR catalyst system 1, under the situation that gets around throttle orifice 7, to set up negative pressure, and observe this negative pressure and whether set up by way of expectations or performance.Illustrate the MEDIA FLOW in backflow model in Fig. 2, this backflow model uses by the present invention.For this reason, No. 4/2 valve 9 switches to the resorption pattern, so medium is released the pipe-line system between metering valve 3 and conveyor module 11 when pump 5 runnings.In the downstream of pump 5, medium leads to back reflow pipe 8 and pumping tube 6 leads and gets back in the reducing agent jar 2.Therefore set up negative pressure between metering valve 3 and pump 5, this negative pressure is utilized by the present invention.Be provided with pressure transducer 10 in this pipe-line system, it can detect one or more measured values of relevant pressure.But therefore detected pressures is for example as the oscillogram of pressure transducer voltage in the time changes.
Fig. 3 shows, when implementing by method of the present invention, and the exemplary experiential oscillogram of variation in pressure.Regional A in the oscillogram top shows pressure sensor signal, as the time variation of pressure transducer voltage.This signal 0bar and-change between the 0.5bar.In the B of oscillogram bottom, show the control of pump motor.Portion's section a) has reflected system before beginning by method of the present invention.This system is not in pressure, and this is following, the about 0bar of pressure sensor signal.After No. 4/2 valve was switched to resorption pattern and control pump motor, normally functioning SCR catalyst system can be set up the negative pressure of Da Yue-0.5bar constantly when metering valve cuts out.At the section c of portion) in closing pump motor and after the resorption that does not change No. 4/2 valve was set, this negative pressure was kept.Infer that thus this system is sealing and normally functioning.In normally functioning system, open metering valve and should be able to make negative pressure suddenly reduce to about 0bar (the section d of portion).Corresponding signal can appear when system damages suddenly.The section e of portion) show signal and change, No. 4/2 valve is set in the resorption pattern in this signal changes, and transfer pump turns round when metering valve seals.The negative pressure of setting up is far from being enough.Deducibility goes out in this case, and the SCR catalyst system has leakage or packing less.
Advantage by method of the present invention is, do not need installation elements extraly just can detect fault in the SCR catalyst system.Another advantage is, excessive aqueous solution of urea can not occur, this situation can occur the method known from prior art, and wherein this system is for realizing that diagnostic purpose loads with superpressure.
By pressing method of the present invention, detect by pressure sensor signal, whether the SCR catalyst system is aspect sealing and can both normally work aspect the element of conveyor module, and described pressure sensor signal has shown foundation and the variation of negative pressure in pipe-line system.The negative pressure of short of foundation expection, then for example transfer pump may be out of order, and the restrictor check valve of transfer pump may be packing less, and No. 4/2 valve may be out of order or be blocked, or metering valve may be out of order or block.In addition, reveal by determining by method of the present invention.Therefore for example can detect the functional of single valve thus, i.e. the described valve of one or many ground control when implementing by method of the present invention.
In order to implement by method of the present invention, multi-way valve is for example changeable to be the resorption pattern, and when metering valve is opened the motor of control transfer pump.Set up negative pressure at this, thereby deducibility goes out, multi-way valve and pump motor are normally functioning.And then may command or close metering valve.If metering valve is normally functioning, then this point should be able to cause the enhancing of negative pressure.Open metering valve and should be able to cause the unexpected reduction of negative pressure.In this variation of negative pressure, it all is normally functioning that deducibility goes out all elements of mentioning, and pipe-line system seals.
Fig. 4 shows another oscillogram, and the variation of the present invention of pressing of the resorption process of medium from pipeline is observed and monitored in the variation of pressure sensor signal when it shows enforcement by method of the present invention in the method.In the A of top, show the variation of pressure transducer voltage once more.In the also control of pump motor shown in the B of bottom.Portion's section a) shows by the method for the present invention sensor signal of the zero hour.At the section b of portion) in illustrated, when motor starts, realize the resorption pattern by switching No. 4/2 valve.Metering valve is opened.Can see the foundation of negative pressure at this, but this negative pressure does not reach 0.5bar (as shown in Figure 3), because compare, at the section b of portion with Fig. 3) in metering valve open.In this stage, medium is drawn back into from pipe-line system in the reducing agent jar.In this affirmation little pressure peak is arranged, it is that motion by diaphragm type pump or transfer pump produces.This resorption pattern is at the section c of portion) in keep.When metering valve unlatching and motor rotation, No. 4/2 valve also remains in the resorption pattern.But this moment, all media are all taken away, and steam bubble enters in the pump case by the metering valve of opening, so pressure can rise.This is the sign that the resorption process closes to an end.At the section d of portion) in, pressure is transferred to high slightly, thick-and-thin level once more when the resorption pattern remains in operation.This moment, medium was taken away fully.Produce pressure peak by diaphragm type pump and no longer can determine, be arranged in pipeline because no longer include medium.By in the resorption process or in the resorption pattern, observing the variation of negative pressure, can observe definitely, how the resorption process carries out, or when the resorption process finish, and promptly all media are all extracted out from pipe-line system.By the present invention ground negative pressure is observed the also resorption of permission monitoring medium from pipe-line system,, when medium freezes, may cause damaging so that can confirm do not have medium to stay in the pipeline.

Claims (10)

1. a monitoring is as the method for the function of the SCR catalyst system (1) of the exhausted gas post-processing system of internal-combustion engine, wherein the SCR catalyst system comprises at least one transfer pump (5), at least one multi-way valve (9), at least one metering valve (3) and at least one pressure transducer (10), it is characterized in that, in the resorption pattern of SCR catalyst system (1), set up by the negative pressure that at least one measured value of pressure transducer (10) is observed in the SCR catalyst system, and when the reference value of described at least one measured value and expection had deviation, then deducibility went out the capability error of SCR catalyst system (1).
2. by the described method of claim 1, it is characterized in that be resorption pattern control multi-way valve (9), therefore when control transfer pump (5), medium is released from the pipeline of SCR catalyst system (1).
3. by claim 1 or 2 described methods, it is characterized in that, before the resorption pattern or during at least temporarily close described at least one metering valve (3).
4. by each described method in the aforesaid right requirement, it is characterized in that, detect the sealing of SCR catalyst system (1).
5. by each described method in the aforesaid right requirement, it is characterized in that, detect the functional of described at least one metering valve (3).
6. by each described method in the aforesaid right requirement, it is characterized in that, detect the functional of described at least one transfer pump (5).
7. by each described method in the aforesaid right requirement, it is characterized in that, detect the functional of described at least one multi-way valve (9).
8. by each described method in the aforesaid right requirement, it is characterized in that, detect the normal variation of resorption process.
9. computer program, when it moves on calculating equipment or controller, implement by each described method in the aforesaid right requirement 1 to 8 in steps.
10. computer program with program-code, this computer program is stored on the machine-readable carrier containing, when this program is moved on calculating equipment or controller, implements by each described method in the claim 1 to 8.
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