CN117536710A - System and method for detecting concentration of urea for vehicle - Google Patents
System and method for detecting concentration of urea for vehicle Download PDFInfo
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- CN117536710A CN117536710A CN202311450090.XA CN202311450090A CN117536710A CN 117536710 A CN117536710 A CN 117536710A CN 202311450090 A CN202311450090 A CN 202311450090A CN 117536710 A CN117536710 A CN 117536710A
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 617
- 239000004202 carbamide Substances 0.000 title claims abstract description 617
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000002347 injection Methods 0.000 claims abstract description 171
- 239000007924 injection Substances 0.000 claims abstract description 171
- 238000012937 correction Methods 0.000 claims abstract description 113
- 238000013500 data storage Methods 0.000 claims abstract description 57
- 238000001514 detection method Methods 0.000 claims abstract description 30
- 230000008859 change Effects 0.000 claims abstract description 16
- 238000004364 calculation method Methods 0.000 claims abstract description 12
- 239000000243 solution Substances 0.000 claims description 40
- 238000012544 monitoring process Methods 0.000 claims description 16
- 238000012795 verification Methods 0.000 claims description 6
- 238000010531 catalytic reduction reaction Methods 0.000 claims description 4
- 238000007689 inspection Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 abstract description 15
- 239000007864 aqueous solution Substances 0.000 abstract description 11
- 238000002425 crystallisation Methods 0.000 abstract description 7
- 230000008025 crystallization Effects 0.000 abstract description 7
- 239000000376 reactant Substances 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 4
- 230000033228 biological regulation Effects 0.000 description 4
- 238000003745 diagnosis Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 231100000572 poisoning Toxicity 0.000 description 4
- 230000000607 poisoning effect Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 239000011593 sulfur Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000005429 filling process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
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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
- 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
- F01N9/00—Electrical control of exhaust gas treating apparatus
- F01N9/007—Storing data relevant to operation of exhaust systems for later retrieval and analysis, e.g. to research exhaust system malfunctions
-
- 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
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
- F01N2900/1806—Properties of reducing agent or dosing system
- F01N2900/1818—Concentration of the reducing agent
Landscapes
- 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)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
The invention relates to a vehicle urea concentration detection system, which comprises a data acquisition unit, a urea concentration calculation unit and a data storage unit. The invention also relates to a method for detecting the concentration of urea for the vehicle, which comprises the following steps: collecting urea injection quantity correction coefficients, readings of a urea quality sensor and data in a data storage unit; judging the validity of the reading of the urea quality sensor according to the reading of the urea quality sensor, the stored concentration change of the urea injected last time and the change of the urea injection quantity correction coefficient after the urea is injected twice; effectively, taking the urea quality sensor value as the urea concentration value of the filling; invalidating, and calculating to obtain the urea concentration value of the filling; storing the data into a data storage unit; and (5) performing iteration. The invention can obtain accurate urea concentration for urea aqueous solution with any concentration; solves the problem of inaccurate reading of a urea quality sensor caused by filling other liquids or bubbles with similar density, urea crystallization and the like; without increasing the risk of emissions exceeding the standard.
Description
Technical Field
The invention relates to the technical field of engine tail gas purification treatment, in particular to a system and a method for detecting concentration of urea for a vehicle.
Background
With the upgrading of diesel emission regulations, the requirements on an engine aftertreatment system are also becoming more stringent; as a mainstream technique for solving the problem of emission of nitrogen oxides, a selective catalytic reduction technique generally uses an aqueous urea solution having a standard concentration of 32.5% as a reducing agent; regulations set that each manufacturer needs to set the minimum acceptable reactant concentration CDmin, and reactants lower than the minimum acceptable reactant concentration CDmin are adverse reactants, and when an OBD system monitors that a vehicle uses urea which needs to be judged as the adverse reactants, a driver alarm system needs to be activated; the vehicle control system can adapt to urea solutions with different concentrations above CDmin, the vehicle control system can gradually increase the urea injection correction coefficient to increase the urea injection amount when the SCR efficiency is at a reduced risk, and gradually decrease the urea injection correction coefficient to decrease the urea injection amount when NH3 leakage exists, so that the emission of NOx and the like can be always ensured to meet the regulation requirement finally.
The current main flow uses urea quality sensor to measure the density of urea aqueous solution mainly through the different transmission rate of ultrasonic wave in the liquid of different density, and then obtains the concentration value of urea. In actual use, the reading of the urea quality sensor is easily influenced by bubbles or urea crystals near the probe, so that the reading is inaccurate, and in addition, if the liquid with the density similar to that of the standard urea aqueous solution is added, the sensor cannot accurately identify, so that the problem of fault false alarm is easily generated, and the customer vehicle experience and the travel efficiency are influenced. The customer car using experience and the trip efficiency are affected.
Typical prior art is named as "a diesel engine urea concentration diagnosis method", the application publication number is CN116085100A, which discloses a diesel engine urea concentration diagnosis method, a urea quality sensor is arranged on a post-treatment device, and the urea quality sensor is in communication connection with an engine ECU; the engine ECU judges whether the CDmin concentration threshold value is exceeded according to the data fed back by the urea quality sensor; the engine ECU judges whether the CDmin efficiency threshold value is exceeded according to the aftertreatment SCR conversion efficiency; the engine ultimately diagnoses the diesel urea concentration by integrating the CDmin concentration threshold and the CDmin efficiency threshold. According to the invention, the SCR conversion efficiency is used as a key condition for diagnosing the concentration CDmin of urea, and the problem of misjudgment of the concentration diagnosis of urea caused by inaccurate measurement of the concentration sensor of urea is avoided through monitoring the SCR conversion efficiency.
The typical prior art is named as a false alarm detection method of a urea concentration sensor, a detection system of the false alarm detection method and an engine of the false alarm detection method, and the false alarm detection system of the false alarm detection engine of the urea concentration sensor, which relate to the technical field of engine detection. Stopping urea injection when the urea concentration detected by the urea concentration sensor is not equal to the threshold value, and detecting whether the urea concentration sensor is false positive; the detection method comprises the following steps: injecting urea with a set injection quantity to obtain a measured value of downstream NOx emission quantity; calculating a theoretical value of NOx participating in the oxidation-reduction reaction according to the set injection amount of urea and the urea concentration detected by the urea concentration sensor; the theoretical value of the downstream NOx emission amount is calculated from the upstream NOx emission amount and the theoretical value of NOx participating in the oxidation-reduction reaction. Calculating a difference between the theoretical value of the downstream NOx emission and the measured value of the downstream NOx emission; judging whether the difference is in a first preset range, if not, judging that the urea concentration sensor is false positive.
The typical prior art is also named as a urea concentration detection method, and the application publication number is CN113847130A, which discloses a urea concentration detection method, and can realize the detection of urea concentration in different working conditions and different temperature ranges. Determining the last acquired urea concentration as the current urea concentration when the temperature range is lower than the freezing temperature of the urea solution; and when the temperature range is higher than the freezing temperature of the urea solution, acquiring the implementation urea concentration of the urea solution, the liquid level difference of the urea solution and the duration time of the liquid level difference under the corresponding working conditions according to different working conditions, and determining the current urea concentration according to the comparison results of the liquid level difference delta H and the liquid level difference threshold range and the duration time t and the time threshold range.
A typical prior art is named as "urea solution concentration monitoring method, device and SCR aftertreatment system", and the chinese application published under number CN113294230a discloses a urea solution concentration monitoring method, which comprises: judging whether urea solution exists in the urea box; when judging that the urea solution exists in the urea box, judging whether the urea concentration of the urea solution is within a concentration threshold range; if the concentration of the urea is not in the concentration threshold range, judging the liquid level stability of the urea solution in the urea box; if the liquid level of the urea solution is in an unstable state, judging whether the urea solution in the urea box is in the filling process or not; and if the urea solution in the urea box is in the filling process, locking the urea concentration of the urea solution detected last time, and returning to judge whether the urea concentration of the urea solution is in a threshold range again after the preset locking time is reached.
A typical prior art is named as a vehicle urea concentration detection device and a vehicle urea concentration detection method, and the application published under the application number CN115683940A is a Chinese invention application which discloses a vehicle urea concentration detection device and a vehicle urea concentration detection method, and calculates the density of urea solution according to the actual liquid level height of the urea solution at the position of a pressure detection unit and the pressure of the urea solution in the urea tank applied to the bottom wall of the urea tank; and calculating the concentration of the urea solution according to the density of the urea solution and the density of water. Even if the vehicle generates bubbles in the urea solution during the running of the vehicle or the urea filling process, the influence of the amount of the bubbles on the height of the urea solution is small and can be ignored; in addition, since the solubility of urea in water is large, the volume change of the solution is small before and after dissolving urea in water, and the change of the volume of the solution before and after dissolving urea in water is negligible compared with the influence of bubbles on the measurement result of the ultrasonic urea quality sensor, so the measurement accuracy of the concentration of the calculated urea solution is high.
The defects of the prior art are that:
the method can only identify the situation that the concentration of the urea aqueous solution is far lower than CDmin, and for the situation that the concentration of the urea aqueous solution is near or higher than CDmin, the SCR efficiency is not obviously reduced because the vehicle control system is required to adapt to the urea aqueous solution according to the regulation requirement, so that the method cannot obtain the accurate concentration of the urea, and can only distinguish whether a sensor with the concentration of the urea being obviously lower than CDmin is wrongly reported or not, and the application range is limited.
The scheme of the patent application 'detection method of false alarm of urea concentration sensor, detection system and engine' complements the defect of the patent 'diagnosis method of urea concentration of diesel engine', which can be used for obtaining relatively accurate urea concentration, but in the process of executing the scheme, the vehicle needs to stop spraying urea first and then spray with fixed ammonia nitrogen ratio, so that the normal urea spraying logic is temporarily shielded, the risk of exceeding the standard of vehicle emission is caused with higher probability, and even if false alarm of urea quality sensor is finally found, the failure of SCR efficiency low or NH3 leakage is caused with higher probability, and the failure rate of the vehicle is increased.
The patent application of ' a urea concentration detection method ', a urea solution concentration monitoring method, a urea concentration monitoring device and an SCR post-treatment system ' is beneficial to reducing false alarms caused by bubbles, crystallization and the like of a urea quality sensor, and improves the data validity of the sensor, but the sensor cannot be identified in the case of filling other liquids with similar densities, so the application range is still limited.
The patent application of the vehicle urea concentration detection device and the vehicle urea concentration detection method calculates the concentration of the urea aqueous solution by accurately calculating the density of the urea aqueous solution, similar to the two previous patents, the concentration of the urea aqueous solution can be accurately obtained, but the method is not applicable to the situation that other liquids with similar densities are filled.
Disclosure of Invention
The present invention is directed to the above-mentioned problems, and an object of the present invention is to provide a system and a method for detecting a concentration of urea in a vehicle, which can identify a case where a concentration of an aqueous urea solution is far lower than CDmin, and can obtain an accurate concentration of urea even when the concentration of the aqueous urea solution is near or higher than CDmin; the risk of exceeding the standard of vehicle emission is not increased; it is possible to identify the situation where other liquids of similar densities are being filled.
In order to solve the problems, the technical scheme provided by the invention is as follows:
a vehicle urea concentration detection system comprises a data acquisition unit, a urea concentration calculation unit and a data storage unit; wherein:
the data acquisition unit is used for acquiring original data; the raw data comprise urea injection quantity correction coefficients, urea quality sensor readings and urea concentration values;
the urea concentration calculating unit is used for calculating the urea concentration value after the urea is filled this time according to the original data acquired by the data acquisition unit;
the data storage unit is used for storing the urea injection quantity correction coefficient and the urea concentration value after the urea is injected this time.
Preferably, the urea injection quantity correction coefficient comprises a urea injection quantity correction coefficient after the urea is injected this time and a urea injection quantity correction coefficient stored after the urea is injected last time; wherein:
The urea injection quantity correction coefficient stored after the last time of urea injection is stored in the data storage unit for being read by the data acquisition unit;
after the urea injection quantity correction coefficient after the new urea injection quantity is filled is collected and used by the urea concentration calculation unit, the urea injection quantity correction coefficient after the urea injection quantity is filled is written into the data storage unit, and the urea injection quantity correction coefficient stored after the urea injection quantity correction coefficient is filled last time is covered.
Preferably, the urea concentration value comprises a urea concentration value after the urea is added at this time and a urea concentration value stored after the urea is added last time; wherein:
the urea concentration value stored after the last time of urea filling is stored in the data storage unit for being read by the data acquisition unit;
when the new urea concentration value after this time of urea filling is collected and used by the urea concentration calculating unit, the urea concentration value after this time of urea filling is written into the data storage unit, and the urea concentration value stored after the last time of urea filling is covered.
A method for detecting the concentration of urea for a vehicle using a system for detecting the concentration of urea for a vehicle comprises the following steps:
S100, monitoring whether the vehicle is filled with urea in real time; and then the following operations are performed according to the monitoring result:
if the vehicle is not urea-filled, returning and executing S100 again from scratch;
starting a time timer if the vehicle is filled with urea for the first time, and starting to accumulate the running time of the vehicle; then, S200 is performed;
s200, comparing the accumulated running time of the vehicle with a first time threshold preset manually; and then according to the comparison result, the following operations are performed:
returning to and executing S200 again if the vehicle run time is less than the first time threshold;
if the running time of the vehicle is not less than the first time threshold, acquiring the urea injection quantity correction coefficient at the current moment and the reading of a urea quality sensor at the current moment; then, S300 is performed;
s300, calculating the ratio of the reading measured by the urea quality sensor to the concentration of the standard vehicle urea solution;
s400, judging whether the reading of the urea quality sensor is valid or not; and then according to the judgment result, the following operations are performed:
if the judgment result is that the reading of the urea quality sensor is valid, the reading of the urea quality sensor is endowed with the current urea concentration value; then S500 is performed;
If the judgment result is that the reading of the urea quality sensor is invalid, giving the urea concentration calculation value to the current urea concentration value; then S500 is performed;
s500, storing the urea injection quantity correction coefficient acquired in the step S200 at the current moment into the data storage unit to serve as the urea injection quantity correction coefficient after the last time of urea injection;
storing the current urea concentration value obtained through S400 verification into the data storage unit to serve as the urea concentration value after the last urea filling; then S600 is performed;
s600, monitoring whether the vehicle is filled with urea in real time again; and then the following operations are performed according to the monitoring result:
if the vehicle is not urea-filled, return and execute S600 again from scratch;
if the vehicle is refilled with urea, starting a time timer again, and starting to re-accumulate the running time of the vehicle; then S700 is performed;
s700, comparing the accumulated running time of the vehicle with a second time threshold preset manually; and then according to the comparison result, the following operations are performed:
returning to and executing S700 again if the vehicle run time is less than the second time threshold;
If the running time of the vehicle is not less than the second time threshold, acquiring the urea injection quantity correction coefficient at the current moment and the reading of the urea quality sensor at the current moment; then reading the urea injection quantity correction coefficient after the last urea injection and the urea concentration value after the last urea injection from the data storage unit; then S800 is performed;
s800, calculating the ratio of the reading measured by the urea quality sensor to the urea concentration value after the last urea filling in the data storage unit; then S900 is performed;
s900, judging whether the reading of the urea quality sensor is valid or not; and then according to the judgment result, the following operations are performed:
if the judgment result is that the reading of the urea quality sensor is valid, the reading of the urea quality sensor is endowed with the current urea concentration value; then S1000 is performed;
if the judgment result is that the reading of the urea quality sensor is invalid, calculating according to the relation between the urea injection quantity correction coefficient change ratio obtained after the last two times of urea injection and the urea concentration value ratio to obtain the current urea concentration value; then S1000 is performed;
S1000, storing the urea injection quantity correction coefficient acquired in the S700 at the current moment into the data storage unit to serve as the urea injection quantity correction coefficient after the last time of urea injection;
storing the current urea concentration value obtained through S900 verification into the data storage unit to serve as the urea concentration value after the last urea filling; then S1100 is performed;
s1100, iteratively executing S600-S1000 until the urea injection quantity correction coefficient is not in a manually preset urea injection quantity correction coefficient range, or an SCR (selective catalytic reduction) efficiency low fault occurs, or a urea consumption high fault occurs, or a urea consumption low fault occurs, and executing S1200;
s1200, resetting the urea concentration value stored by the data storage unit to 32.5% and locking; resetting and locking the urea injection quantity correction coefficient stored in the data storage unit to 1; then S1300 is performed;
s1300, checking whether the urea injection quantity correction coefficient returns to the urea injection quantity correction coefficient range, and eliminating the fault of SCR efficiency and the fault of high urea consumption and the fault of low urea consumption; then, according to the inspection result, the following operations are made:
If the urea injection amount correction coefficient is returned to the urea injection amount correction coefficient range and the SCR efficiency low fault is disappeared and the urea consumption high fault is disappeared and the urea consumption low fault is disappeared, returning to and re-executing S100 again;
if the urea injection quantity correction coefficient does not return to the urea injection quantity correction coefficient range, or the SCR low efficiency fault does not disappear, or the urea consumption high fault does not disappear, or the urea consumption low fault does not disappear, returning to and re-executing S1300 again.
Preferably, the value range of the first time threshold is 1 hour to 3 hours.
Preferably, the ratio of the reading measured by the urea quality sensor to the standard vehicle urea solution concentration in S300 is expressed as follows:
B 1 ＝ω 1 /32.5％
wherein: b (B) 1 A ratio of the reading measured by the urea quality sensor to the standard vehicle urea solution concentration; omega 1 For readings measured by the urea quality sensor.
Preferably, in S400, it is determined whether the current reading of the urea quality sensor is valid, and the method specifically includes the following steps:
s410, calculating a first reference value, wherein the first reference value is expressed by the following formula:
C 1 ＝|A 1 /B 1 -1|
wherein: c (C) 1 Is the first reference value; a is that 1 Collecting the urea injection quantity correction coefficient at the current moment in S200;
S420, comparing the first reference value with a first reference value threshold preset manually; and then according to the comparison result, the following operations are performed:
if the first reference value is smaller than the first reference value threshold value, judging that the reading of the urea quality sensor is valid at the present time;
if the first reference value is not less than the first reference value threshold, it is determined that the current reading of the urea quality sensor is invalid.
Preferably, the urea concentration calculation is expressed as follows:
ω c ＝32.5％/A 1
wherein: omega c A value is calculated for the urea concentration.
Preferably, the ratio of the reading measured by the urea quality sensor in S800 to the urea concentration value after the last urea filling in the data storage unit is expressed by the following formula:
B 2 ＝ω 2 /ω
wherein: b (B) 2 A ratio of the reading measured by the urea quality sensor to the urea concentration value in the data storage unit after the last urea filling; omega 2 Is a reading of the urea quality sensor in S700; ω is the urea concentration value after the last urea filling read from the data storage unit in S700.
Preferably, in S900, it is determined whether the current reading of the urea quality sensor is valid, and the method specifically includes the following steps:
S910, calculating a second reference value, wherein the second reference value is expressed by the following formula:
C 2 ＝|A 2 /(A*B 2 )-1|
wherein: c (C) 2 Is the second reference value; a is that 2 Collecting the urea injection quantity correction coefficient at the current moment in S700; a is the urea injection quantity correction coefficient after the last urea injection read from the data storage unit in S700;
s920, comparing the second reference value with a second reference value threshold preset manually; and then according to the comparison result, the following operations are performed:
if the second reference value is smaller than the second reference value threshold value, judging that the reading of the urea quality sensor is valid at the present time;
if the second reference value is not smaller than the second reference value threshold value, judging that the reading of the urea quality sensor is invalid at the present time;
in S900, the current urea concentration value is calculated according to the relationship between the urea injection quantity correction coefficient change ratio obtained after the last two urea injections and the urea concentration value ratio, and is expressed by the following formula:
ω'＝ω*A/A 2
wherein: ω' is the urea concentration value at this time.
Compared with the prior art, the invention has the following advantages:
1. the invention can not only identify the situation that the concentration of the urea aqueous solution is far lower than CDmin, but also obtain accurate urea concentration when the concentration of the urea aqueous solution is near or higher than CDmin, thereby greatly widening the application field compared with the prior art;
2. According to the invention, urea does not need to be sprayed firstly and then at a fixed ammonia nitrogen ratio, and normal urea spraying logic is not required to be shielded temporarily, so that the risk of exceeding the standard of vehicle emission caused by probability does not exist, and the source reason of raising the vehicle failure rate caused by SCR (selective catalytic reduction) efficiency failure or NH3 leakage failure caused by the risk is eliminated;
3. the application area is further widened, since the invention also makes it possible to identify the situation in which other liquids of similar density are filled.
Drawings
FIG. 1 is a schematic flow chart of a method embodying the present invention.
Detailed Description
The present invention is further illustrated below in conjunction with specific embodiments, it being understood that these embodiments are meant to be illustrative of the invention only and not limiting the scope of the invention, and that modifications of the invention, which are equivalent to those skilled in the art to which the invention pertains, will fall within the scope of the invention as defined in the claims appended hereto.
It should be noted in advance that the principle of the present invention is as follows:
and judging whether the reading of the urea quality sensor is effective or not by utilizing the linear relation between the urea injection quantity correction coefficient and the urea concentration after each urea injection, if so, recording the reading of the sensor as the concentration of the urea in the tank, otherwise, calculating the concentration of the urea in the tank by adopting the change of the urea injection coefficient value after continuous urea injection twice and the recorded urea concentration recorded after the last urea injection. And when the recorded concentration of the urea in the tank is smaller than CDmin, judging that the concentration of the urea is low.
Ideally, the vehicle runs for a period of time after each urea injection, the urea injection correction coefficient and the urea concentration are in a inversely related linear relationship, for example, when the urea concentration is reduced by 10%, the urea injection correction coefficient is gradually stabilized in a 10% increasing state, and the concentration of the urea in the tank can be accurately estimated through the change condition of the urea injection correction coefficient after two continuous urea injection and the concentration of the urea in the last tank. However, in practical use, the urea injection quantity correction coefficient is also affected by SCR urea crystallization, SCR sulfur poisoning, inaccurate injection quantity caused by urea pump problems, etc., so that the SCR efficiency may gradually deviate from the efficiency in a normal state, and further the urea injection quantity correction coefficient is affected, so that a linear relationship between a change of the urea injection quantity correction coefficient and a change of the urea concentration may have a small fluctuation, and be approximately linearly related.
Normally, both SCR urea crystallization and SCR sulfur poisoning are slow gradual processes, and the influence of the SCR urea crystallization and SCR sulfur poisoning on the urea injection correction coefficient is far slower than the change of the urea injection correction coefficient caused by the change of the urea concentration; high/low urea consumption failures are typically caused by problems with the urea pump or nozzle, which can be easily removed once they occur, which can be quickly reported. Therefore, the approximate linear relation between the urea injection quantity correction coefficient and the urea concentration can be utilized to judge whether the reading of the urea quality sensor is available or not, and the urea concentration value after the urea is injected this time is calculated, and the accuracy of calculating the urea concentration can be effectively improved by reasonably selecting the reading and the calculated value of the urea quality sensor. The accurate concentration value is utilized to diagnose the quality of the injected urea, so that the problem of false alarm fault caused by the influences of bubbles, urea crystallization and the like on the reading of the sensor can be effectively avoided; the condition that the urea quality sensor cannot recognize due to the fact that other liquids with similar density to the standard urea solution are filled can be accurately recognized; in addition, the scheme does not interfere with the inherent urea injection logic of the vehicle, and does not cause the problem of excessive emission. The invention is beneficial to reducing false alarm of vehicle faults and improving the driving experience and the transportation efficiency of users.
A vehicle urea concentration detection system comprises a data acquisition unit, a urea concentration calculation unit and a data storage unit; wherein:
the data acquisition unit is used for acquiring original data; the raw data includes urea injection quantity correction coefficients, urea mass sensor readings, and urea concentration values.
The urea concentration calculating unit is used for calculating the urea concentration value after the urea is filled according to the original data acquired by the data acquisition unit.
The data storage unit is used for storing the urea injection quantity correction coefficient and the urea concentration value after the urea is injected.
In this embodiment, the urea injection quantity correction coefficient includes a urea injection quantity correction coefficient after the current urea injection and a urea injection quantity correction coefficient stored after the last urea injection; wherein:
the urea injection quantity correction coefficient stored after the last time of filling urea is stored in the data storage unit for being read by the data acquisition unit.
After the urea injection quantity correction coefficient after the new urea injection is collected and used by the urea concentration calculation unit, the urea injection quantity correction coefficient after the new urea injection is written into the data storage unit to cover the urea injection quantity correction coefficient stored after the previous urea injection.
In this embodiment, the urea concentration value includes a urea concentration value after the current urea injection and a urea concentration value stored after the previous urea injection; wherein:
the urea concentration value stored after the last time of urea filling is stored in the data storage unit for being read by the data acquisition unit.
When the new urea concentration value after the urea is added is collected and used by the urea concentration calculating unit, the urea concentration value after the urea is added is written into the data storage unit to cover the stored urea concentration value after the urea is added last time.
As shown in fig. 1, a method for detecting the concentration of urea for a vehicle using a system for detecting the concentration of urea for a vehicle comprises the steps of:
s100, monitoring whether the vehicle is filled with urea in real time; and then the following operations are performed according to the monitoring result:
if the vehicle is not being urea-filled, it returns and is again performed from scratch S100.
Starting a time timer if the vehicle is filled with urea for the first time, and starting to accumulate the running time of the vehicle; then, S200 is performed;
s200, comparing the accumulated running time of the vehicle with a first time threshold preset manually; and then according to the comparison result, the following operations are performed:
If the vehicle running time is less than the first time threshold, S200 is returned and executed again.
If the running time of the vehicle is not less than the first time threshold, acquiring a urea injection quantity correction coefficient at the current moment and a reading of a urea quality sensor at the current moment; then S300 is performed.
In this embodiment, the value range of the first time threshold is 1 to 3 hours.
S300, calculating the ratio of the reading measured by the urea quality sensor to the concentration of the standard vehicle urea solution.
In this specific embodiment, the ratio of the reading measured by the urea quality sensor in S300 to the standard vehicle urea solution concentration is expressed by the formula (1):
B 1 ＝ω 1 /32.5％ (1)
wherein: b (B) 1 The ratio of the reading measured by the urea quality sensor to the concentration of the standard vehicle urea solution; omega 1 Is a reading measured by a urea quality sensor.
S400, judging whether the reading of the urea quality sensor is valid or not; and then according to the judgment result, the following operations are performed:
if the judgment result is that the reading of the current urea quality sensor is valid, the reading of the current urea quality sensor is endowed with the current urea concentration value; then S500 is performed.
If the judgment result is that the reading of the current urea quality sensor is invalid, giving the calculated value of the urea concentration to the current urea concentration value; then S500 is performed.
In this particular embodiment, the urea concentration calculation is expressed by the formula (2):
ω c ＝32.5％/A 1 (2)
wherein: omega c Calculated for urea concentration.
In this embodiment, in S400, it is determined whether the reading of the current urea quality sensor is valid, and the method specifically includes the following steps:
s410, calculating a first reference value, wherein the first reference value is expressed according to a formula (3):
C 1 ＝|A 1 /B 1 -1| (3)
wherein: c (C) 1 Is a first reference value; a is that 1 And (5) acquiring a urea injection quantity correction coefficient at the current moment in S200.
S420, comparing the first reference value with a first reference value threshold preset manually; and then according to the comparison result, the following operations are performed:
if the first reference value is smaller than the first reference value threshold value, judging that the reading of the urea quality sensor is valid at the present time;
if the first reference value is not less than the first reference value threshold, it is determined that the current urea quality sensor reading is invalid.
In this embodiment, the value range of the first reference value threshold is 3% -5%.
S500, storing the urea injection quantity correction coefficient acquired in the step S200 at the current moment into a data storage unit, and taking the urea injection quantity correction coefficient as the urea injection quantity correction coefficient after the last urea injection.
Storing the current urea concentration value obtained through the verification of the S400 into a data storage unit to serve as a urea concentration value after the last urea injection; then S600 is performed.
S600, monitoring whether the vehicle is filled with urea in real time again; and then the following operations are performed according to the monitoring result:
if the vehicle is not being urea-filled, it returns and is again performed from scratch S600.
If the vehicle is refilled with urea, starting a time timer again, and starting to re-accumulate the running time of the vehicle; then S700 is performed.
S700, comparing the accumulated running time of the vehicle with a second time threshold preset manually; and then according to the comparison result, the following operations are performed:
if the vehicle running time is less than the second time threshold, S700 is returned and executed again.
If the running time of the vehicle is not less than the second time threshold, acquiring a urea injection quantity correction coefficient at the current moment and a reading of a urea quality sensor at the current moment; then reading a urea injection quantity correction coefficient after the last urea injection and a urea concentration value after the last urea injection from a data storage unit; then S800 is performed;
in this embodiment, the value of the second time threshold ranges from 1 hour to 3 hours.
S800, calculating the ratio of the reading measured by the urea quality sensor to the urea concentration value after the last urea injection in the data storage unit; then S900 is performed.
In this specific embodiment, the ratio of the reading measured by the urea quality sensor in S800 to the urea concentration value after the last urea injection in the data storage unit is expressed according to formula (4):
B 2 ＝ω 2 /ω (4)
wherein: b2 is the ratio of the reading measured by the urea quality sensor to the urea concentration value after the last urea injection in the data storage unit; ω2 is the reading of the urea quality sensor in S700; ω is the value of the urea concentration after the last urea injection read from the data storage unit in S700.
S900, judging whether the reading of the urea quality sensor is valid or not; and then according to the judgment result, the following operations are performed:
if the judgment result is that the reading of the current urea quality sensor is valid, the reading of the current urea quality sensor is endowed with the current urea concentration value; then S1000 is performed.
If the judgment result is that the reading of the current urea quality sensor is invalid, calculating to obtain a current urea concentration value according to the relation between the urea injection quantity correction coefficient change ratio obtained after the last two times of urea injection and the urea concentration value ratio; then S1000 is performed.
In this embodiment, in S900, it is determined whether the reading of the current urea quality sensor is valid, and the method specifically includes the following steps:
S910, calculating a second reference value, wherein the second reference value is expressed as the formula (5):
C 2 ＝|A 2 /(A*B 2 )-1|(5)
wherein: c (C) 2 Is a second reference value; a is that 2 Collecting a urea injection quantity correction coefficient at the current moment in S700; a is the urea injection amount correction coefficient after the last urea injection read from the data storage unit in S700.
S920, comparing the second reference value with a second reference value threshold preset manually; and then according to the comparison result, the following operations are performed:
if the second reference value is smaller than the second reference value threshold value, judging that the reading of the urea quality sensor is valid at the present time;
if the second reference value is not less than the second reference value threshold, it is determined that the current urea quality sensor reading is invalid.
In this embodiment, the value range of the first reference value threshold is 3% -5%.
In S900, the current urea concentration value is calculated according to the relationship between the urea injection quantity correction coefficient change ratio obtained after the last two urea injections and the urea concentration value ratio, and expressed according to the formula (6):
ω'＝ω*A/A 2 (6)
wherein: omega' is the urea concentration value of this time.
S1000, storing the urea injection quantity correction coefficient acquired in the S700 at the current moment into a data storage unit, and taking the urea injection quantity correction coefficient as the urea injection quantity correction coefficient after the last urea injection.
Storing the current urea concentration value obtained through the verification of the S900 into a data storage unit to serve as a urea concentration value after the last urea injection; then S1100 is performed.
S1100, iteratively executing S600-S1000 until the urea injection quantity correction coefficient is not in the range of the urea injection quantity correction coefficient preset manually, or the SCR efficiency is low, or the urea consumption is high, or the urea consumption is low, and executing S1200.
In the process of executing S600 to S1000, particularly, considering the factor interference such as the higher/lower urea injection amount caused by the SCR crystallization, sulfur poisoning, and urea pump problem, the ratio of the urea injection amount correction coefficient to the urea concentration may gradually deviate from the linearly related state, so when the urea injection correction out-of-range fault (the urea injection amount correction coefficient exceeds the upper limit or is lower than the lower limit), or the SCR efficiency is low, or the urea consumption is high/low, the calculated urea concentration is considered to be invalid, at this time, the stored urea concentration ω is reset to 32.5% and locked, the stored urea injection amount correction coefficient a is reset to 1 and locked, until the next urea injection is identified after the urea injection correction out-of-range fault/SCR efficiency low/urea consumption high/urea consumption low and other faults disappear, the method process is restarted from S100; this is the execution basis of S1200 to S1300.
S1200, resetting the urea concentration value stored in the data storage unit to 32.5% and locking; resetting and locking the urea injection quantity correction coefficient stored in the data storage unit to 1; then S1300 is performed.
S1300, checking whether the urea injection quantity correction coefficient returns to the urea injection quantity correction coefficient range, and eliminating the low-efficiency fault of SCR, the high-consumption fault of urea and the low-consumption fault of urea; then, according to the inspection result, the following operations are made:
if the urea injection quantity correction coefficient is returned to the urea injection quantity correction coefficient range and the SCR efficiency low fault is disappeared and the urea consumption high fault is disappeared and the urea consumption low fault is disappeared, returning to and re-executing S100 again;
if the urea injection quantity correction coefficient does not return to the urea injection quantity correction coefficient range, or the SCR low efficiency fault does not disappear, or the urea consumption high fault does not disappear, or the urea consumption low fault does not disappear, then return to and re-execute S1300 again.
In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate preferred embodiment of this invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. As will be apparent to those skilled in the art; various modifications to these embodiments will be readily apparent, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing description includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, as used in the specification or claims, the term "comprising" is intended to be inclusive in a manner similar to the term "comprising," as interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean "non-exclusive or".
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The utility model provides a urea concentration detecting system for automobile-used which characterized in that: comprises a data acquisition unit, a urea concentration calculation unit and a data storage unit; wherein:
the data acquisition unit is used for acquiring original data; the raw data comprise urea injection quantity correction coefficients, urea quality sensor readings and urea concentration values;
the urea concentration calculating unit is used for calculating the urea concentration value after the urea is filled this time according to the original data acquired by the data acquisition unit;
the data storage unit is used for storing the urea injection quantity correction coefficient and the urea concentration value after the urea is injected this time.
2. The urea concentration detection system for a vehicle according to claim 1, wherein: the urea injection quantity correction coefficient comprises a urea injection quantity correction coefficient after the urea is injected this time and a urea injection quantity correction coefficient stored after the urea is injected last time; wherein:
The urea injection quantity correction coefficient stored after the last time of urea injection is stored in the data storage unit for being read by the data acquisition unit;
after the urea injection quantity correction coefficient after the new urea injection quantity is filled is collected and used by the urea concentration calculation unit, the urea injection quantity correction coefficient after the urea injection quantity is filled is written into the data storage unit, and the urea injection quantity correction coefficient stored after the urea injection quantity correction coefficient is filled last time is covered.
3. The urea concentration detection system for a vehicle according to claim 2, characterized in that: the urea concentration value comprises a urea concentration value after the urea is added at this time and a urea concentration value stored after the urea is added last time; wherein:
the urea concentration value stored after the last time of urea filling is stored in the data storage unit for being read by the data acquisition unit;
when the new urea concentration value after this time of urea filling is collected and used by the urea concentration calculating unit, the urea concentration value after this time of urea filling is written into the data storage unit, and the urea concentration value stored after the last time of urea filling is covered.
4. A method for detecting the concentration of urea for a vehicle using the system for detecting the concentration of urea for a vehicle according to claim 2, characterized by: comprises the following steps:
s50, executing a first urea concentration adding detection flow;
s600, monitoring whether the vehicle is filled with urea in real time again; and then the following operations are performed according to the monitoring result:
if the vehicle is not urea-filled, return and execute S600 again from scratch;
if the vehicle is refilled with urea, starting a time timer again, and starting to re-accumulate the running time of the vehicle; then S700 is performed;
s700, comparing the accumulated running time of the vehicle with a second time threshold preset manually; and then according to the comparison result, the following operations are performed:
returning to and executing S700 again if the vehicle run time is less than the second time threshold;
if the running time of the vehicle is not less than the second time threshold, acquiring the urea injection quantity correction coefficient at the current moment and the reading of the urea quality sensor at the current moment; then reading the urea injection quantity correction coefficient after the last urea injection and the urea concentration value after the last urea injection from the data storage unit; then S800 is performed;
S800, calculating the ratio of the reading measured by the urea quality sensor to the urea concentration value after the last urea filling in the data storage unit; then S900 is performed;
s900, judging whether the reading of the urea quality sensor is valid or not; and then according to the judgment result, the following operations are performed:
if the judgment result is that the reading of the urea quality sensor is valid, the reading of the urea quality sensor is endowed with the current urea concentration value; then S1000 is performed;
if the judgment result is that the reading of the urea quality sensor is invalid, calculating according to the relation between the urea injection quantity correction coefficient change ratio obtained after the last two times of urea injection and the urea concentration value ratio to obtain the current urea concentration value; then S1000 is performed;
s1000, storing the urea injection quantity correction coefficient acquired in the S700 at the current moment into the data storage unit to serve as the urea injection quantity correction coefficient after the last time of urea injection;
storing the current urea concentration value obtained through S900 verification into the data storage unit to serve as the urea concentration value after the last urea filling; then S1100 is performed;
S1100, iteratively executing S600-S1000 until the urea injection quantity correction coefficient is not in a manually preset urea injection quantity correction coefficient range, or an SCR (selective catalytic reduction) efficiency low fault occurs, or a urea consumption high fault occurs, or a urea consumption low fault occurs, and executing S1200;
s1200, resetting the urea concentration value stored by the data storage unit to 32.5% and locking; resetting and locking the urea injection quantity correction coefficient stored in the data storage unit to 1; then S1300 is performed;
s1300, checking whether the urea injection quantity correction coefficient returns to the urea injection quantity correction coefficient range, and eliminating the fault of SCR efficiency and the fault of high urea consumption and the fault of low urea consumption; if the check results in that the above conditions are all satisfied, S50 is re-executed when the next urea injection is identified.
5. The method for detecting the concentration of urea for a vehicle according to claim 4, wherein: the first urea concentration detection flow in S50 specifically includes the following steps:
s100, monitoring whether the vehicle is filled with urea in real time; and then the following operations are performed according to the monitoring result:
if the vehicle is not urea-filled, returning and executing S100 again from scratch;
Starting a time timer if the vehicle is filled with urea for the first time, and starting to accumulate the running time of the vehicle; then, S200 is performed;
s200, comparing the accumulated running time of the vehicle with a first time threshold preset manually; and then according to the comparison result, the following operations are performed:
returning to and executing S200 again if the vehicle run time is less than the first time threshold;
if the running time of the vehicle is not less than the first time threshold, acquiring the urea injection quantity correction coefficient at the current moment and the reading of a urea quality sensor at the current moment; then, S300 is performed;
s300, calculating the ratio of the reading measured by the urea quality sensor to the concentration of the standard vehicle urea solution;
s400, judging whether the reading of the urea quality sensor is valid or not; and then according to the judgment result, the following operations are performed:
if the judgment result is that the reading of the urea quality sensor is valid, the reading of the urea quality sensor is endowed with the current urea concentration value; then S500 is performed;
if the judgment result is that the reading of the urea quality sensor is invalid, giving the urea concentration calculation value to the current urea concentration value; then S500 is performed;
S500, storing the urea injection quantity correction coefficient acquired in the step S200 at the current moment into the data storage unit to serve as the urea injection quantity correction coefficient after the last time of urea injection;
storing the current urea concentration value obtained through S400 verification into the data storage unit to serve as the urea concentration value after the last urea filling; then S600 is performed;
in S1300, if the check result is that all the above conditions are satisfied, when the next urea injection is identified, S50 is re-executed, which specifically includes the following steps:
according to the inspection result, the following operations are made:
if the urea injection amount correction coefficient is returned to the urea injection amount correction coefficient range and the SCR efficiency low fault is disappeared and the urea consumption high fault is disappeared and the urea consumption low fault is disappeared, returning to and re-executing S100 again;
if the urea injection quantity correction coefficient does not return to the urea injection quantity correction coefficient range, or the SCR low efficiency fault does not disappear, or the urea consumption high fault does not disappear, or the urea consumption low fault does not disappear, returning to and re-executing S1300 again.
The value range of the first time threshold is 1-3 hours.
6. The method for detecting the concentration of urea for a vehicle according to claim 5, characterized in that: the ratio of the reading measured by the urea quality sensor to the standard vehicle urea solution concentration in S300 is expressed as:
B 1 ＝ω 1 /32.5％
wherein: b (B) 1 A ratio of the reading measured by the urea quality sensor to the standard vehicle urea solution concentration; omega 1 For readings measured by the urea quality sensor.
7. The method for detecting the concentration of urea for a vehicle according to claim 6, characterized in that: s400, judging whether the reading of the urea quality sensor is valid or not, wherein the method specifically comprises the following steps:
s410, calculating a first reference value, wherein the first reference value is expressed by the following formula:
C 1 ＝|A 1 /B 1 -1|
wherein: c (C) 1 Is the first reference value; a is that 1 Collecting the urea injection quantity correction coefficient at the current moment in S200;
s420, comparing the first reference value with a first reference value threshold preset manually; and then according to the comparison result, the following operations are performed:
if the first reference value is smaller than the first reference value threshold value, judging that the reading of the urea quality sensor is valid at the present time;
if the first reference value is not less than the first reference value threshold, it is determined that the current reading of the urea quality sensor is invalid.
8. The method for detecting the concentration of urea for a vehicle according to claim 7, characterized in that: the urea concentration calculation is expressed as follows:
ω c ＝32.5％/A 1
wherein: omega c A value is calculated for the urea concentration.
9. The urea concentration detection method for a vehicle according to claim 8, characterized in that: the ratio of the reading measured by the urea quality sensor in S800 to the urea concentration value after the last urea filling in the data storage unit is expressed as follows:
B 2 ＝ω 2 /ω
wherein: b (B) 2 A ratio of the reading measured by the urea quality sensor to the urea concentration value in the data storage unit after the last urea filling; omega 2 Is a reading of the urea quality sensor in S700; omega is the upper read from the data storage unit in S700And (3) the urea concentration value after one urea injection.
10. The urea concentration detection method for a vehicle according to claim 9, characterized in that: s900, judging whether the reading of the urea quality sensor is valid or not, wherein the method specifically comprises the following steps:
s910, calculating a second reference value, wherein the second reference value is expressed by the following formula:
C 2 ＝|A 2 /(A*B 2 )-1|
wherein: c (C) 2 Is the second reference value; a is that 2 Collecting the urea injection quantity correction coefficient at the current moment in S700; a is the urea injection quantity correction coefficient after the last urea injection read from the data storage unit in S700;
S920, comparing the second reference value with a second reference value threshold preset manually; and then according to the comparison result, the following operations are performed:
if the second reference value is smaller than the second reference value threshold value, judging that the reading of the urea quality sensor is valid at the present time;
if the second reference value is not smaller than the second reference value threshold value, judging that the reading of the urea quality sensor is invalid at the present time;
in S900, the current urea concentration value is calculated according to the relationship between the urea injection quantity correction coefficient change ratio obtained after the last two urea injections and the urea concentration value ratio, and is expressed by the following formula:
ω'＝ω*A/A 2
wherein: ω' is the urea concentration value at this time.
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