CN110513180A - Vehicle SCR systems and its return flow measurement module and measuring method - Google Patents
Vehicle SCR systems and its return flow measurement module and measuring method Download PDFInfo
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- CN110513180A CN110513180A CN201810488913.0A CN201810488913A CN110513180A CN 110513180 A CN110513180 A CN 110513180A CN 201810488913 A CN201810488913 A CN 201810488913A CN 110513180 A CN110513180 A CN 110513180A
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000005259 measurement Methods 0.000 title claims abstract description 35
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- 230000008569 process Effects 0.000 claims abstract description 24
- 238000010992 reflux Methods 0.000 claims description 28
- 238000002347 injection Methods 0.000 claims description 13
- 239000007924 injection Substances 0.000 claims description 13
- 239000007789 gas Substances 0.000 description 113
- 230000008859 change Effects 0.000 description 7
- 238000005314 correlation function Methods 0.000 description 7
- 238000013022 venting Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 3
- 238000010531 catalytic reduction reaction Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 2
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- 239000007864 aqueous solution Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000019771 cognition Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
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- 238000005859 coupling reaction Methods 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 230000003137 locomotive effect Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
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- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- 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
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
-
- 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
- F01N2610/1473—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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- 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
Abstract
A kind of vehicle SCR systems return flow measurement module is used to measure the vent gas treatment flow quantity to flow back when SCR system work from the feed unit of SCR system to flow container, the measurement module is configured to execute operations described below: the vent gas treatment liquid in the feed unit is emptied, so that realizing the maximum volume of air under 0 bar of relative pressure in the feed unit；Later, vent gas treatment liquid is introduced into the feed unit, so that establishing routine work pressure when SCR system work in the feed unit；Later, so that the vent gas treatment liquid in the feed unit discharges naturally so that the feed unit nature pressure release, while the pressure in the feed unit and pressure release elapsed-time standards being detected；Later, the relationship based on pressure and pressure release elapsed-time standards in the feed unit in pressure leak process determines vent gas treatment liquid return flow when SCR system works.
Description
Technical field
In SCR (selective catalytic reduction) system that this application involves a kind of for vehicle, especially diesel-engine road vehicle
Vent gas treatment liquid return flow measures module and return flow measuring method, and the vehicle SCR system comprising this measurement module
System.
Background technique
In order to post-process to vehicle startup tail gas, SCR system is used.SCR system can be by vent gas treatment liquid
(usually aqueous solution of urea) is ejected into tail gas, to reduce the NOx amount in tail gas using selective catalytic reduction.
SCR system generally includes feed unit, for the vent gas treatment liquid in flow container to be supplied to injection unit.Supply is single
Member is connected to flow container by aspiration line and reflux pipeline.In SCR system work, feed unit passes through aspiration line from flow container
Vent gas treatment liquid is extracted, and a part of vent gas treatment liquid in feed unit is fed into injection unit, at extra tail gas
Reason liquid flows back into flow container through reflux pipeline.Reflux restricting element is equipped in reflux pipeline.Through return pipe when feed unit works
The flow of the vent gas treatment liquid of line reflux is an important parameter in SCR system, such as SCR system control and various
The calibration and adjustment of correlation function.In general, the return flow of vent gas treatment liquid is designed to be located within the scope of a return flow,
The range of flow is determined by metered flow plus a plus-minus tolerance value.The considerations of for many factors, such as avoid because of measurement
Return flow fluctuation beyond the return flow range and frequently alarm, which is normally set up larger.However, producing in this way
Raw big return flow range can impact the correlation function of SCR system.(disappear for example, will affect vent gas treatment liquid CDM
Consume deviation monitoring) function etc..There are difficulty for the calibration and adjustment that return flow range big in this way leads to these functions, i.e., difficult
With determination calibration value appropriate to cover this big return flow range.For this return flow range of constriction, Ke Yigai
Become the hardware design of stream restricting element again, and this will lead to the increase of cost.
Summary of the invention
For reason described above, the purpose of the application is to provide a kind of improved SCR system vent gas treatment liquid reflux
Flow measurement scheme can more precisely measure the tail when SCR system work under the premise of not being modified to hardware
Gas disposal liquid return flow.
According to the one aspect of the application, provide a kind of for returning in vehicle (especially diesel locomotive) SCR system
It flowing flow (such as mass flow) and measures module, being returned when for measuring SCR system work from the feed unit of SCR system to flow container
The vent gas treatment flow quantity of stream, the measurement module are configured to execute operations described below: emptying the tail gas in the feed unit
Treatment fluid in the feed unit so that realize the maximum volume of air under 0 bar of relative pressure；Later, by vent gas treatment liquid
It is introduced into the feed unit so as to establish routine work pressure when SCR system work in the feed unit；Later, by institute
It states the vent gas treatment liquid in feed unit to be discharged naturally so that the feed unit nature pressure release, while detecting the feed unit
In pressure and pressure release elapsed-time standards；Later, based in the feed unit in pressure leak process pressure and pressure release through lasting
Between relationship determine SCR system work when vent gas treatment liquid return flow.
According to further aspect of the application, a kind of vehicle SCR systems are provided, including previously described return flow is surveyed
Cover half block, the return flow of vent gas treatment liquid when being used to measure SCR system work.
According to further aspect of the application, a kind of return flow measuring method in vehicle SCR systems is provided,
It is executed optionally by previously described return flow measurement module, and the method includes the following steps: emptying SCR system
Vent gas treatment liquid in feed unit, so that realizing the maximum air body under 0 bar of relative pressure in the feed unit of SCR system
Product；Later, vent gas treatment liquid is introduced into the feed unit to be established in the feed unit when SCR system works
Routine work pressure；Later, so that the vent gas treatment liquid in the feed unit discharges naturally so that the feed unit is natural
Pressure release, while detecting the pressure in the feed unit and pressure release elapsed-time standards；Later, based on the supply in pressure leak process
The relationship of pressure and pressure release elapsed-time standards in unit determines vent gas treatment liquid return flow when SCR system work.
According to the application, SCR system is determined based on the natural venting duration and pressure of the vent gas treatment liquid in feed unit
Vent gas treatment liquid finite reflux flow when work, therefore accurate return flow can be obtained.In such manner, it is possible to realize more
Accurate SCR system control and the calibration and adjustment of various correlation functions.Simultaneously, it is not necessary to reflux restricting element and correlation
Device makes the change on hardware, thus can be to avoid increased costs.
Detailed description of the invention
Fig. 1 is the schematic diagram according to a kind of SCR system of embodiments possible of the application；
Fig. 2 is the variation schematic diagram of residual air volume of the feed unit of SCR system in natural pressure leak process；
Fig. 3-6 is supplied with pressure drop and vent gas treatment flow quantity time history plot in unit emptying operation；
Fig. 7 is to explain the signal for emptying feed unit in the vent gas treatment liquid return flow measurement scheme of the application
Figure；
Fig. 8 is according to a kind of the schematic of the vent gas treatment liquid return flow measuring method of embodiments possible of the application
Flow chart.
Specific embodiment
The preferred embodiment of the application is described with reference to the accompanying drawings.
Fig. 1 shows the tail gas of an embodiment according to the application being used in vehicle, especially diesel-engine road vehicle
SCR system is associated with, for reducing the NOx in tail gas with the exhaust pipe 1 of vehicle motor.The SCR system includes being arranged in
SCR catalyst 2 and injection unit 3 in exhaust pipe 1.Injection unit 3 is located at 2 upstream of SCR catalyst, for that will come from flow container 4
Vent gas treatment liquid (such as urea liquid) be ejected into tail gas stream in a manner of metering so that tail gas is mixed with vent gas treatment liquid
And catalytic reduction reaction occurs in SCR catalyst 2, by NOx conversion at nitrogen and water.
Feed unit 5 is used to the vent gas treatment liquid in flow container 4 being supplied to injection unit 3.The operation of feed unit 5 by
The control unit 6 of SCR system controls.The control unit 6 also controls the operation of injection unit 3.Control unit 6 can be SCR system
An individual controller in system, also can integrate in control unit of engine or vehicle ECU.Control unit 6 is based on hair
The operation of the operating control SCR system of motivation.
Aspiration line 7 is connected between feed unit 5 and flow container 4, and pressure line 8 is connected to feed unit 5 and injection is single
Between member 3.There is main pump (not shown), for extracting flow container 4 by aspiration line 7 in SCR system work in feed unit 5
In vent gas treatment liquid, and vent gas treatment liquid is supplied to by injection unit 3 by pressure line 8.In addition, feed unit 5 and liquid
Reflux pipeline 9 is also arranged between tank 4, for making a part of vent gas treatment liquid with certain reflux stream when SCR system works
AmountIn from feed unit 5 back to flow container 4.Restricting element 10, the return flow are arranged in reflux pipeline 9Mainly
It is determined by factors such as vent gas treatment hydraulic coupling, the circulation areas of restricting element 10.
Vent gas treatment liquid return flow when the application is intended to be accurately determined SCR system workFor this purpose, the application provides
A kind of vent gas treatment liquid return flow measures module.According to a kind of embodiments possible, which measures module setting
In control unit 6.According to other embodiments possibles, return flow measurement module be can be set in control unit of engine
Or in vehicle ECU.Return flow measurement module is arranged to vent gas treatment liquid return flow when measurement SCR system workReturn flow measurement module is also arranged to be able to the control hair in the measurement operation for executing vent gas treatment liquid return flow
The cooperating of motivation and SCR system.
The vent gas treatment liquid return flow measurement scheme of the application based on letting out the vent gas treatment liquid in feed unit 5 naturally
The understanding that pressure and flow when pressure change with time.This is explained referring to Fig. 2-Fig. 6.
The situation of change in the vent gas treatment liquid nature pressure leak process in feed unit 5 is investigated with reference first to Fig. 2.Fig. 2 with
Left-half and right half part respectively indicate the feed unit 5 before nature pressure release and after natural pressure release, wherein being represented by dotted lines confession
To the liquid level of the vent gas treatment liquid in unit 5.
As shown in the left-half of Fig. 2, after SCR system stops working, main pump stops working, aspiration line 7, pressure pipe
Line 8 is all to close, and the vent gas treatment liquid in feed unit 5 has initial pressure, substantially the routine work pressure of SCR system
(such as 5 bars of relative pressures).In addition, in the ullage of vent gas treatment liquid, there are residual airs.At this point, residual air is supplied to
Vent gas treatment hydraulic compression in unit 5, volume V0.Meanwhile (including supply is single for each elastic element acted on by vent gas treatment liquid
First 5 inner walls, the pressure compensation unit 11 in feed unit 5, pressure line 8 etc.) deformed by the pushing of vent gas treatment liquid.
Next, being closed, under the situation of the opening of reflux pipeline 9 in aspiration line 7 and pressure line 8, in feed unit 5
Vent gas treatment liquid acts on, under the reset response of each elastic element in itself pressure effect, the pushing of residual air, through with section
The reflux pipeline 9 of fluid element 10 flows back into flow container 4, so that natural pressure release in feed unit 5, until the tail in feed unit 5
The pressure of gas disposal liquid becomes 0 bar of relative pressure, as shown in the right half part of Fig. 2.At this point, the liquid level in feed unit 5 declines,
The volume of residual air increases to Vair(it can be calculated by equation for ideal gases, for example, when initial pressure is 5 bars of relative pressures,
Vair=6 V0), each elastic element also restores its original shape.In natural pressure leak process, through reflux pipeline 9 from feed unit 5
Displaced volume is V altogetherDEFVent gas treatment liquid.
The application is (basic to the pressure in feed unit 5 in natural pressure leak process for a variety of different residual air amounts
Upper is also the pressure of the vent gas treatment liquid in feed unit 5) and the mass flow of vent gas treatment liquid that is discharged through reflux pipeline 9 do
It investigates.Fig. 3,4 are residual air volume V after pressure release respectivelyairA period of time of natural pressure leak process in the case where being 2 milliliters
Middle pressure and mass flow with venting duration change curve.Fig. 5,6 are residual air volume V after pressure release respectivelyairIt is 50 milliliters
In the case where natural pressure leak process a period of time in pressure and mass flow with venting duration change curve.It is other after pressure release
Residual air volume VairThe case where also similarly investigated.
Pressure in pressure leak process natural in the case where different residual air amounts is compared with the variation of mass flow more permissible
It learns, the residual air amount in feed unit 5 is bigger, and the pressure drop rate in feed unit 5 is smaller, and pressure reaches some pre- level pressure
Time needed for force value (such as 1 bar or 2 bars of relative pressures) is longer, and the mass flow of vent gas treatment liquid is bigger, the tail given off
Gas disposal liquid measure (as shown in the hatched area below the curve in Fig. 4,6) is bigger.
Based on above-mentioned cognition, the application is proposed, the initial pressure in feed unit 5 is the routine work pressure of SCR system
In the case where, some scheduled pressure value institute is dropped to from initial pressure based on the pressure in feed unit 5 in natural pressure leak process
The time needed or the pressure value after experienced one section of predetermined time based on natural pressure leak process in feed unit 5 determine confession
Vent gas treatment liquid emission flow when to 5 initial pressure release of unit, vent gas treatment liquid returns when being substantially equal to SCR system work
Flow flow
As before it is found that in natural pressure leak process, in the emission flow and feed unit 5 of vent gas treatment liquid
Residual air amount is related.The return flow of vent gas treatment liquid when in order to calculate SCR system workNeed first to learn that supply is single
Residual air amount in member 5.For this purpose, the application proposes, maximum air that may be present under 0 bar of relative pressure in feed unit 5
It is calculated on the basis of volume.This maximum volume of air can be obtained by following manner, that is, in 5 pressure release of feed unit to 0
After bar relative pressure, so that the vent gas treatment liquid in feed unit 5 continues to discharge naturally towards in flow container 4, until in feed unit 5
The emptying of vent gas treatment liquid, such as it is shown in Fig. 7.This maximum volume of air is also considered as at the tail gas in feed unit 5
Manage the maximum air containment after liquid empties in feed unit 5.In this way, just obtaining in feed unit 5 under 0 bar of relative pressure most
Big volume of air.
In this regard it may be noted that feed unit 5 is drained, it is believed that the vent gas treatment liquid being supplied in unit 5
The degree that can not be further discharged is arrived, it is possible to have the vent gas treatment liquid that can not be discharged of remaining.Due to the nothing of remaining
The vent gas treatment liquid measure very little of method discharge, does not influence the measurement of return flow, therefore be not considered.
It may be noted that due to being provided with vent gas treatment liquid emptier in SCR system, it can be completely or partially
The vent gas treatment liquid in feed unit 5 is discharged by means of vent gas treatment liquid emptier and introduce air with realize it is described most
Big volume of air.It is of course also possible to realize discharge and the air of the vent gas treatment liquid in feed unit 5 by other measures
It introduces.
About the vent gas treatment liquid emptier, it should be pointed out that, in order to prevent vent gas treatment after engine end of run
Liquid freezes or crystallizes in SCR system, which can be with the vent gas treatment liquid court in coercively fed unit 5
Flow container 4 flows back.Vent gas treatment liquid emptier is not described further herein.
In the state of engine misses, the return flow measurement module can be forced by vent gas treatment liquid emptier
Vent gas treatment liquid in feed unit 5 flows back towards flow container 4.At this point, aspiration line 7 is to close, pressure line 8 and reflux pipeline
9 are open.In this way, the vent gas treatment liquid in feed unit 5 can be discharged into bottom line, and will be outer by pressure line 8
Boundary's air is introduced into feed unit 5, so that the air in feed unit 5 reaches the maximum volume of air under 0 bar of relative pressure,
I.e. in feed unit 5.Since the structure of feed unit 5 is precognition, the maximum volume of air under this 0 bar of relative pressure
And be known in advance, for example, 60 milliliters.
After the maximum volume of air that the air in feed unit 5 reaches under 0 bar of relative pressure, the return flow measurement
Module makes engine start, while SCR system starts, so that feed unit 5 extracts vent gas treatment through aspiration line 7 from flow container
Liquid, so that vent gas treatment liquid establishes pressure in feed unit 5, until reach routine work pressure (such as 5 bars of relative pressures),
Injection unit 3 starts to spray vent gas treatment liquid.In this process, aspiration line 7, reflux pipeline 9 are all open, pressure pipe
The open and-shut mode of line 8 is determined by the working condition of injection unit 3.Then, the return flow measurement module puts out engine
Fire, and aspiration line 7, pressure line 8 are closed, reflux pipeline 9 is open, so that at the tail gas in feed unit 5
Liquid is managed by reflux pipeline 9 to 4 natural back flow of flow container, so that feed unit 5 is by natural pressure release.During natural pressure release, detection
Pressure in pressure release elapsed-time standards and feed unit 5.The return flow measurement module is based on the pressure in detection feed unit 5
Time for undergoing when dropping to scheduled pressure value or natural pressure leak process experienced the pressure after the predetermined time in feed unit 5
Power, come the return flow of vent gas treatment liquid when calculating SCR system work
Be described below according to a kind of embodiments possible of the application dropped to based on the pressure in detection feed unit 5 it is pre-
The return flow of vent gas treatment liquid when the time undergone when level pressure force value calculates SCR system workProcess.
Firstly, the volume V of the vent gas treatment liquid to flow back through the reflux pipeline 9 with restricting element 10DEFEqual to feed unit
Residual air volume V in 5airSwell increment plus each elastic element shape restore caused by volume (for example, VEEIndicate that pressure is flat
The volume of weighing apparatus unit 11, VhousingIndicate the volume of the shell of feed unit 5, VPLIndicate the volume of pressure line 8) increment, then
Obtain the equation of following differential forms:
dVDEF=dVair+dVelastic=dVair+(dVEE+dVhousing+dVPL) (1)
Flow through the mass flow of the vent gas treatment liquid of restricting element 10It is directly proportional to the square root of pressure p, thus obtain
Following formula:
Wherein, k is parameter relevant to 10 area of restricting element and treatment fluid density, and ρ is the density of vent gas treatment liquid.
It is available according to equation for ideal gases:
(p0+1)·V0=(p+1)·Vair
Therefore,
Therefore following formula is obtained:
For each elastic element, the volume restored during the pressure relief process is expressed as following formula:
dVelastic=ke·dp (4)
Wherein, keFor the coefficient of elasticity of elastic element.
Based on above-mentioned various (1), (2), (3), (4), the return flow of vent gas treatment liquid when can find out SCR system work
Wherein, VairFor the maximum volume of air under 0 bar of relative pressure in feed unit 5；
p0The pressure (such as 5 bars of relative pressures) in unit, i.e. SCR system routine work pressure are initially supplied to for pressure release；
P is the pressure in pressure leak process in feed unit；
T is from p0The time that pressure release is undergone to p.
It may be noted that acting on each elastic element if there is no by vent gas treatment liquid, then it can remove k in above formula (5)e.
In formula (5), parameter Vair、p0、p、ρ、keDeng all predefine or measure, the time t needs only undergone
Real-time measurement.Therefore, formula (5) can be further simplified as following form:
According to a kind of specific algorithm example of the application, vent gas treatment liquid when finding out SCR system work with following formula
Return flow
Wherein, C is the parameter for embodying the pressure that is initially supplied in unit to volume change during zero relative pressure.
Due to the parameter in formula (7)p0、p、ρ、keDeng all predefine or measure, the time t needs only undergone
Real-time measurement, therefore formula (6), (7) can simplify as following linear representation:
Wherein, C1And C2It is that residual air amount determines i.e. confirmable constant when program starts,The only letter of time
Number.Using formula (8), calculating process can be greatly simplified, shortens and calculates the time.
It is the reflux stream of vent gas treatment liquid when can determine that SCR system works using specific formula above or simplified formula
AmountIn view of factors such as the tolerances of pressure sensor and restricting element quality stream, to select pressure release to suitable predetermined pressure
The point of value is used for above-mentioned calculating, such as p is 1 or 2 bar of relative pressure, naturally it is also possible to which it is pre- for selecting other values according to actual needs
Level pressure force value.
According to a kind of modification, the time t that pressure release is undergone is fixed into (such as taking about 2~3 seconds), and detects pressure release warp
The pressure p after time t in feed unit is gone through, and using pressure p as the reflux of vent gas treatment liquid when determining SCR system work
FlowFormula in variable.For example, SCR system work when vent gas treatment liquid return flowCalculation formula can be general
It includes into:
Or it is reduced to following linear representation:
Those skilled in the art can extrapolate specific function and constant in formula (5)~(10), no longer retouch in detail here
It states.
It may be noted that in previously described example, the return flow of the vent gas treatment liquid of measurementFor mass flow, sheet
Application is equally applicable to the return flow of the other forms of measurement vent gas treatment liquid.
According to embodiments herein described above, a kind of vent gas treatment liquid for SCR system time can be constructed
Flow determining method is flowed, as shown in the schematic flow chart in Fig. 8.
In step sl, vehicle motor is flame-out, closes the feed unit and injection unit of SCR system.
Next, in step s 2, the emptying of feed unit is executed, until the air capacity in feed unit reaches 0 bar of phase
To the maximum volume of air under pressure.In this step, it can be forced fully or in part by means of vent gas treatment liquid emptier real
The emptying of existing feed unit.
Next, in step s3, engine start, SCR system starting.
Next, in step s 4, establishing pressure because of the vent gas treatment liquid of introducing in the feed unit of SCR system, directly
Reach SCR system routine work pressure.
Next, in step s 5, vehicle motor is flame-out, the feed unit and injection unit of SCR system are closed, so that
Aspiration line, pressure line are closed, and reflux pipeline is open, so that feed unit nature pressure release.
Next, in step s 6, timer timing since at the time of vehicle motor stops working, while it is single to detect supply
Pressure in member.
Next, in the step s 7, judging whether the pressure in feed unit drops to scheduled pressure value (such as 2 bars).
If it is judged that being no, then return step S6；If it is judged that be it is yes, then follow the steps S8.
In step s 8, timer stops, and thus obtains the time needed for the calculating of vent gas treatment liquid return flow.
Next, in step s 9, the reflux stream of vent gas treatment liquid when calculating SCR system work as variable using the time
Amount.It can use previously described the separate equations and calculate the return flow, especially simplified formula.
It is appreciated that vent gas treatment liquid return flow measuring method can also be built into experienced scheduled venting duration
The pressure in feed unit is variable to calculate the residual air amount in feed unit afterwards.In this return flow measuring method
In, include the steps that with previously mentioned identical S1 to S6, and from previously mentioned different step S7 to S9:
In the step s 7, judge whether the timing of timer reaches predetermined time (such as 2 seconds).If it is judged that being
It is no, then return step S6；If it is judged that be it is yes, then follow the steps S8.
In step s 8, pressure when reaching the predetermined time in feed unit is determined.
Next, in step s 9, when calculating SCR system work as variable using the pressure in the feed unit at tail gas
Manage the return flow of liquid.It can use previously described the separate equations and calculate the return flow, especially simplified formula.
The vent gas treatment liquid return flow determination process of the application can execute before vehicle release, and subsequent
In vehicle use process at a time interval or mileage travelled interval execute.
Front referring to Fig.1-7 and various formula for the SCR system and the return flow measurement module description
Therefore the vent gas treatment liquid return flow measuring method that various features are equally applicable to the application is not repeated to describe.Another party
Face, the vent gas treatment liquid return flow measuring method of the application can measure module by previously described return flow and execute, with
And applied in the SCR system of the application.
Technology is determined according to the SCR system vent gas treatment liquid return flow of the application, at the tail gas in feed unit
The natural venting duration and pressure (value of alternative one predefines, another value is detected) for managing liquid determine that SCR system works
When vent gas treatment liquid finite reflux flow, therefore accurate return flow can be obtained, so as to more accurately real
The various correlation functions (such as CDM, leak detection etc.) of existing SCR system.In addition, accurate return flow provided by the present application
Input value needed for determining value can be used as the calibration and adjustment of various correlation functions, to improve the control precision of SCR system
And the precision of calibration and the adjustment of correlation function.Furthermore it is possible to mitigate the calibration and adjustment work of various correlation functions.
In addition, the application does not need to design return flow range for constriction and do reflux restricting element and related device
Change on hardware out, thus can be to avoid increased costs.
In addition, the return flow measurement module of the application can be the software module in corresponding control unit/controller
Form is not required to add new hardware, thus can further avoid increased costs.
Although describing the application herein with reference to specific embodiment, scope of the present application is not limited to shown
Details.Without departing from the basic principle of the application, various modifications can be made for these details.
Claims (10)
1. a kind of return flow of vehicle SCR systems measures module, from the supply of SCR system when for measuring SCR system work
The vent gas treatment flow quantity that unit flows back to flow container, the measurement module are configured to execute operations described below:
The vent gas treatment liquid in the feed unit is emptied so that realizing under 0 bar of relative pressure most in the feed unit
Big volume of air；
Later, vent gas treatment liquid is introduced into the feed unit so as to be established in the feed unit when SCR system works
Routine work pressure；
Later, the vent gas treatment liquid in the feed unit is discharged naturally so that the feed unit nature pressure release, is examined simultaneously
Survey the pressure and pressure release elapsed-time standards in the feed unit；
Later, SCR system is determined based on the relationship of pressure and pressure release elapsed-time standards in the feed unit in pressure leak process
Vent gas treatment liquid return flow when work.
2. return flow as described in claim 1 measures module, wherein the return flow measurement module is configured to be based on
Pressure in SCR system nature pressure leak process in feed unit drops to the scheduled pressure value time experienced to determine
Vent gas treatment liquid return flow when SCR system works, the scheduled pressure value are, for example, about 2 bars；
Optionally, the return flow measurement module is configured with using the time as the formula of variable, especially linear list
Vent gas treatment liquid return flow when SCR system work is determined up to formula.
3. return flow as described in claim 1 measures module, wherein the return flow measurement module is configured to be based on
Pressure in SCR system nature pressure leak process when pressure release experienced the predetermined time in feed unit determines that SCR system works
When vent gas treatment liquid return flow, the predetermined time is, for example, 2~3 seconds；
Optionally, the return flow measurement module is configured with using the pressure in feed unit as the formula of variable, especially
It is linear representation to determine vent gas treatment liquid return flow when SCR system work.
4. return flow as claimed any one in claims 1 to 3 measures module, wherein empty in the feed unit
The step of vent gas treatment liquid, is executed after vehicle motor and the SCR system stop working, optionally, by means of described
Vent gas treatment liquid emptier in SCR system executes.
5. return flow according to any one of claims 1 to 4 measures module, wherein will be described in the introducing of vent gas treatment liquid
Step in feed unit is realized and by vehicle motor and SCR system starting.
6. the return flow as described in any one of claims 1 to 5 measures module, wherein the return flow measures module
It is configured to obtain receiving vent gas treatment liquid in SCR system to determine vent gas treatment liquid return flow when SCR system work
The coefficient of elasticity of the elastic element of pressure, the elastic element include the shell of such as feed unit, the pressure in feed unit
Balancing unit, the pressure line being connected with feed unit.
7. as return flow described in any one of claims 1 to 6 measures module, wherein the return flow measures module
It is configured to control the operation of vehicle motor and SCR system during return flow measures；
Optionally, the return flow measurement module is arranged in the control unit of SCR system, or setting is controlled in engine
In unit, or it is arranged in vehicle ECU.
8. the return flow as described in any one of claims 1 to 7 measures module, wherein the SCR system includes: tail gas
Handle flow container；Feed unit is connect by aspiration line and reflux pipeline with vent gas treatment flow container；And injection unit,
It is connect by pressure line with feed unit；
Wherein, the return flow measurement module is configured to the shape opened in aspiration line and pressure line closing, reflux pipeline
The natural pressure release of the feed unit is realized under condition.
9. a kind of vehicle SCR systems, including such as return flow described in any item of the claim 1 to 8 measures module, is used for
The return flow of vent gas treatment liquid when measuring SCR system work.
10. a kind of return flow measuring method in vehicle SCR systems, optionally by any in claim 1 to 8
Return flow measurement module described in executes, and the method includes the following steps:
The vent gas treatment liquid in the feed unit of SCR system is emptied, so that realizing 0 bar of opposite pressure in the feed unit of SCR system
Maximum volume of air under power；
Later, when vent gas treatment liquid being introduced into the feed unit to establish SCR system work in the feed unit
Routine work pressure；
Later, so that the vent gas treatment liquid in the feed unit discharges naturally so that the feed unit nature pressure release, simultaneously
Detect the pressure and pressure release elapsed-time standards in the feed unit；
Later, SCR system is determined based on the relationship of pressure and pressure release elapsed-time standards in the feed unit in pressure leak process
Vent gas treatment liquid return flow when work.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112648058A (en) * | 2021-01-04 | 2021-04-13 | 东风汽车股份有限公司 | Urea injection device of engine SCR system and fault diagnosis method thereof |
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|---|---|---|---|---|
| CN101631952A (en) * | 2007-02-22 | 2010-01-20 | 罗伯特·博世有限公司 | Test device and method for checking injection components |
| CN107002574A (en) * | 2014-12-15 | 2017-08-01 | 大陆汽车有限公司 | Method for running Diesel engine |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101631952A (en) * | 2007-02-22 | 2010-01-20 | 罗伯特·博世有限公司 | Test device and method for checking injection components |
| CN107002574A (en) * | 2014-12-15 | 2017-08-01 | 大陆汽车有限公司 | Method for running Diesel engine |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112648058A (en) * | 2021-01-04 | 2021-04-13 | 东风汽车股份有限公司 | Urea injection device of engine SCR system and fault diagnosis method thereof |
| CN112648058B (en) * | 2021-01-04 | 2022-02-18 | 东风汽车股份有限公司 | Urea injection device of engine SCR system and fault diagnosis method thereof |
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