CN114991921B - SCR (selective catalytic reduction) low-efficiency fault cause investigation method - Google Patents
SCR (selective catalytic reduction) low-efficiency fault cause investigation method Download PDFInfo
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- CN114991921B CN114991921B CN202210583690.2A CN202210583690A CN114991921B CN 114991921 B CN114991921 B CN 114991921B CN 202210583690 A CN202210583690 A CN 202210583690A CN 114991921 B CN114991921 B CN 114991921B
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000011835 investigation Methods 0.000 title abstract description 11
- 238000010531 catalytic reduction reaction Methods 0.000 title abstract description 6
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 115
- 239000004202 carbamide Substances 0.000 claims abstract description 115
- 238000001514 detection method Methods 0.000 claims abstract description 41
- 239000012535 impurity Substances 0.000 claims abstract description 18
- 239000000243 solution Substances 0.000 claims description 37
- 239000007788 liquid Substances 0.000 claims description 14
- 238000002347 injection Methods 0.000 claims description 10
- 239000007924 injection Substances 0.000 claims description 10
- 238000013024 troubleshooting Methods 0.000 claims description 9
- 238000011065 in-situ storage Methods 0.000 claims description 6
- 238000003745 diagnosis Methods 0.000 claims description 3
- 239000007921 spray Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 12
- 230000015556 catabolic process Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000006731 degradation reaction Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000005086 pumping Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 238000006722 reduction reaction 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]
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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
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
- F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
-
- 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
- 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
-
- 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
-
- 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
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)
- Exhaust Gas After Treatment (AREA)
Abstract
The utility model relates to the technical field of exhaust aftertreatment systems, in particular to an SCR (selective catalytic reduction) low-efficiency fault cause investigation method. The technical proposal comprises: checking whether the urea solution meets the requirements or not through a urea mass concentration detection module and a urea impurity detection module; the NOX sensor detection module is used for checking whether the NOX sensor works normally or not; checking whether urea can be normally injected; and (3) checking the detection faults and carrying out corresponding treatment, and if the detection results are normal, replacing the SCR. According to the utility model, the reason of the low SCR efficiency is accurately judged by checking item by item in a feedback way, and the detection methods are mutually combined, so that the effect of improving the checking efficiency is achieved, and a user can conveniently recover the SCR efficiency by adopting a targeted method.
Description
Technical Field
The utility model relates to the technical field of exhaust aftertreatment systems, in particular to an SCR (selective catalytic reduction) low-efficiency fault cause investigation method.
Background
At present, a truck running on a road is basically a vehicle in five countries, and the national six emission regulation is also implemented in 7 months and 1 day in 2020, and is clearly required in the national six regulation, and if the emission of the whole vehicle exceeds the regulation requirement, a series of operations such as lighting, limiting torsion and the like are required for the vehicle.
The national diesel engines are matched with the aftertreatment systems of a catalytic oxidizer (DOC) +a particulate filter (DPF) +a selective oxidation-reduction device (SCR) for reducing NOx and particulate emissions in engine exhaust gas. Whether the regulation is national four, national five or national six, the alarm is required to be carried out after the NOx emission of the tail gas exceeds the regulation limit value, and the torsion and speed limiting can be carried out when the NOx emission is too high to influence the driving of a driver, so that the fault of the reduction of the SCR efficiency can be accurately predicted, the related operation is carried out to recover the SCR efficiency, and the alarm, the torsion limiting and the speed limiting are further avoided.
Through a large number of searches, the following findings are found: chinese patent special column: the application number CN202111104525.6 and the publication number CN113779494A are used for carrying out SCR fault diagnosis, wherein the conversion efficiency calculation parameters of the SCR to be detected are recorded and input into an SCR conversion efficiency calculation function to obtain conversion efficiency values of the SCR to be detected corresponding to N information acquisition time windows; inputting the conversion efficiency value of the SCR to be detected into a probability density function of the SCR conversion efficiency to obtain a probability value of the SCR to be detected corresponding to each information acquisition window as a degradation piece; inputting N probability values of the SCR to be detected, which correspond to the N information acquisition time windows, as the degradation piece into a probability factor calculation function of the SCR as the degradation piece to obtain a probability factor of the SCR as the degradation piece; and determining that the SCR fails when the probability factor that the SCR is a degradation member is greater than a preset probability factor. However, the troubleshooting method is complex, needs professional personnel to operate, has higher cost of the troubleshooting device and lower practicability, is based on the higher cost, and is highly needed to be operated simply, has higher practicability and lower cost, and the fault troubleshooting method of the tail gas aftertreatment system is used for troubleshooting the reason of low SCR efficiency, guiding the after-sale related operation to recover the SCR efficiency, further avoiding alarming, torsion limiting and speed limiting, and improving the user experience.
Disclosure of Invention
The utility model provides an SCR (selective catalytic reduction) low-efficiency fault cause investigation method, which solves the technical problems.
The scheme for solving the technical problems is as follows:
the utility model provides an SCR inefficiency fault cause investigation system, including the urea mass concentration detection module that is used for urea concentration to detect, be used for urea impurity detection's urea impurity detection module and be used for gaseous NOX sensor detection module that detects, through the combination feedback investigation of urea mass concentration detection module, urea impurity detection module and NOX sensor detection module to the cause of accurate judgement SCR inefficiency, thereby adopts the targeted method to resume SCR efficiency.
Further, the urea mass concentration detection module is a refractometer, the urea impurity detection module is oil test paper, and the NOX sensor detection module is a nitrogen oxide detector.
Further, urea solution is dripped on a refractometer prism, and the refractive index of the urea solution is read by a refractometer to measure the urea concentration, so that the urea concentration is used for checking SCR fault factors caused by the urea mass concentration; judging whether the urea solution contains oil according to whether the oil test paper changes color, and checking SCR fault factors caused by urea solution impurities; the NOx value of the NOx sensor in the data flow in the idle state is detected by a gas sensor in the nitrogen oxide detector to be in a normal range or not, and the NOx value is used for checking SCR fault factors caused by the NOx sensor.
An SCR (selective catalytic reduction) low-efficiency fault cause investigation method comprises the following steps:
checking whether the urea solution meets the requirements or not through a urea mass concentration detection module and a urea impurity detection module; the NOX sensor detection module is used for checking whether the NOX sensor works normally or not; checking whether urea can be normally injected; and (3) checking the detection faults and carrying out corresponding treatment, and if the detection results are normal, replacing the SCR.
The beneficial effects of the utility model are as follows: the method comprises the steps of sequentially checking whether the urea mass concentration is normal, whether the urea solution has impurities, whether the NOX sensor is normal, whether the urea pump builds pressure normally, whether the SCR itself has defects and the like, checking by item-by-item feedback to accurately judge the reason of low SCR efficiency, combining the detection methods, thereby achieving the effect of improving the checking effectiveness, and facilitating a user to recover the SCR efficiency by adopting a targeted method. Therefore, compared with a comparison file, the method is simple to operate, the method is high in practicability, the cause of the low SCR efficiency is accurately judged, and meanwhile the detection cost is low.
On the basis of the technical scheme, the utility model can be improved as follows.
Further, the working flow for checking whether the urea solution meets the requirements is as follows:
1) Checking the liquid level of the urea box, ensuring that the liquid level of the urea box is moderate, and removing excessive urea solution or insufficient urea solution;
2) Taking a small amount of urea from a urea box by using a proper tool, dripping the urea on a refractometer prism, and reading the refractive index of the urea solution by using a refractometer to measure the concentration of the urea;
3) And (5) detecting whether the urea solution contains oil or not by using oil test paper.
Further, if the concentration of the urea solution is not in the range of 30.5% -34.5%, the standard urea solution is replaced.
Further, if the test paper changes color, the oil in the urea solution is indicated, the clean urea solution is replaced, and the SCR hydraulic system is cleaned.
Further, the method for checking whether the NOX sensor can normally operate is as follows: whether the NOX value in the data flow passing through the universal diagnostic instrument is in a reasonable range in the idle state; if the NOx value is not within the range, the NOx sensor is replaced.
Further, checking whether urea can be injected normally specifically includes: removing the nozzle from the EGP, stepping on the accelerator in situ, and observing whether the urea injection system can normally build pressure for injection; if the urea injection cannot be normally performed, the failure of the system pressure establishment is checked.
Further, the system step-down failure fault investigation flow comprises the following steps:
the diagnosis instrument is connected to ensure that the engine has no electrical appliance fault code; a transparent urea liquid inlet pipe is used, one end of the transparent liquid return pipe is connected with a urea pump, and the other end is connected with a urea barrel; igniting the engine, stepping on the accelerator in situ to ensure that the exhaust temperature reaches more than 180 ℃ and the pressure building condition is met; the diagnostic apparatus detects whether the pressure is normally built.
The foregoing description is only an overview of the present utility model, and is intended to provide a better understanding of the present utility model, as it is embodied in the following description, with reference to the preferred embodiments of the present utility model and the accompanying drawings. Specific embodiments of the present utility model are given in detail by the following examples and the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this application, illustrate embodiments of the utility model and together with the description serve to explain the utility model and do not constitute a limitation on the utility model.
In the drawings:
FIG. 1 is a schematic diagram of an SCR inefficiency troubleshooting process of the present utility model;
fig. 2 is a schematic diagram of a system depressurization failure troubleshooting process according to the present utility model.
Detailed Description
The principles and features of the present utility model are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the utility model and are not to be construed as limiting the scope of the utility model. The utility model is more particularly described by way of example in the following paragraphs with reference to the drawings. Advantages and features of the utility model will become more apparent from the following description and from the claims. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the utility model.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When a component is considered to be "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used herein in the description of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The present utility model will be described in further detail with reference to the following specific embodiments.
Example 1
The utility model provides an SCR inefficiency fault cause investigation system, including the urea mass concentration detection module that is used for urea concentration to detect, be used for urea impurity detection's urea impurity detection module and be used for gaseous NOX sensor detection module that detects, through the combination feedback investigation of urea mass concentration detection module, urea impurity detection module and NOX sensor detection module to the cause of accurate judgement SCR inefficiency, thereby adopts the targeted method to resume SCR efficiency.
Further, the urea mass concentration detection module is a refractometer, the urea impurity detection module is oil test paper, and the NOX sensor detection module is a nitrogen oxide detector.
Further, urea solution is dripped on a refractometer prism, and the refractive index of the urea solution is read by a refractometer to measure the urea concentration, so that the urea concentration is used for checking SCR fault factors caused by the urea mass concentration; judging whether the urea solution contains oil according to whether the oil test paper changes color, and checking SCR fault factors caused by urea solution impurities; the NOx value of the NOx sensor in the data flow in the idle state is detected by a gas sensor in the nitrogen oxide detector to be in a normal range or not, and the NOx value is used for checking SCR fault factors caused by the NOx sensor.
An SCR inefficiency troubleshooting method, in combination with fig. 1, includes:
A. checking whether the urea mass concentration is normal
The method for analyzing the urea mass concentration comprises the steps of reading the refractive index of a urea solution through a refractometer, reading the refractive index, measuring the urea mass concentration according to the refractive index, and judging that the cause of low SCR efficiency is poor in urea mass if the urea mass concentration is not in a reasonable range, wherein the range of the reasonable value is 30.5-34.5%;
B. checking the urea solution for impurities
After the quality concentration of the urea is determined to be normal, the oil test paper is required to be used for detecting whether the urea solution contains oil or not, if the test paper changes color, the oil in the urea solution is indicated, and the clean urea solution is required to be replaced and the SCR hydraulic system is required to be cleaned;
C. checking whether the NOx sensor is working properly
After determining that the urea solution is free of impurities, whether the NOX sensor can work normally or not needs to be checked, and the checking method is as follows: under the idle working condition, using a diagnostic instrument to check whether an NOX sensor in a data stream is in a reasonable range, wherein the range of a reasonable value is different along with engines with different displacement, for example, a 2.5L engine and an engine with a rated power of 125KW are used as examples, and under the idle working condition, the NOX value is in a reasonable range of 150-220PPM;
D. checking whether the urea injection system can normally build pressure
After the NOX sensor works normally, checking whether the urea injection system can build up pressure normally or not, wherein the method comprises the following steps: the nozzle was removed from the EGP for viewing, stepping on the throttle in situ into a condition that could be sprayed: the exhaust temperature is more than the temperature limit, whether normal pressure building injection can be performed is observed, the temperature limit is basically about 190-220 ℃ according to different engine displacement, and if the normal injection cannot be performed, the fault detection of the urea pump pressure building failure is required to be checked;
E. replacement of SCR
If the urea injection system can normally build pressure and inject urea, the SCR efficiency is caused by SCR crystallization, SCR poisoning and the like, and the SCR needs to be replaced.
And after the SCR has low efficiency, checking the aftertreatment system, wherein the checking sequence is that the urea mass concentration, the urea solution has impurities, an NOX sensor, the urea pump builds pressure and the SCR. The method comprises the steps of sequentially checking whether the urea mass concentration is normal, whether the urea solution has impurities, whether the NOX sensor is normal, whether the urea pump builds pressure normally, whether the SCR itself has defects and the like, checking by item-by-item feedback to accurately judge the reason of low SCR efficiency, combining the detection methods, thereby achieving the effect of improving the checking efficiency, and being convenient for a user to recover the SCR efficiency by adopting a targeted method. Therefore, compared with a comparison file, the method is simple to operate, the method is high in practicability, the cause of the low SCR efficiency is accurately judged, and meanwhile the detection cost is low.
Example two
Compared with the first embodiment, the utility model provides the method for checking the failure cause of the low SCR efficiency, which further comprises the following steps: the system step-down failure fault checking method is described in detail with reference to fig. 2, wherein the system step-down failure fault checking flow is as follows:
step one, connecting a diagnostic instrument to ensure that an engine has no electrical appliance fault code;
step two, using a transparent urea liquid inlet pipe, wherein one end of the transparent liquid return pipe is connected with a urea pump, and the other end of the transparent liquid return pipe is connected with a urea barrel;
step three, the engine is ignited, and the accelerator is stepped on in situ, so that the exhaust temperature reaches more than 180 ℃, and the pressure building condition is met;
step four, the diagnostic instrument detects whether the pressure is normally built, if the pressure does not reach the required value in unit time in the pressure building process, the post-treatment state jumps from the pressure building stage to reverse pumping (considering the air influence in the pipeline), the pressure is built again after a period of reverse pumping, and if the reverse pumping is still unsuccessful for 2 times, the system reports the pressure building failure fault;
if so, detecting whether the pipeline and the urea box filter screen are blocked or not, cleaning or replacing related parts;
if not, checking whether a filter screen at a liquid inlet of the pump is blocked;
if the liquid inlet filter screen is blocked, the filter screen needs to be cleaned or replaced;
if the liquid inlet filter screen is not blocked, the urea pump needs to be replaced.
The above description is only of the preferred embodiments of the present utility model, and is not intended to limit the present utility model in any way; those skilled in the art will readily appreciate that the present utility model may be implemented as shown in the drawings and described above; however, those skilled in the art will appreciate that many modifications, adaptations, and variations of the present utility model are possible in light of the above teachings without departing from the scope of the utility model; meanwhile, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the present utility model still fall within the scope of the present utility model.
Claims (3)
1. The method for checking the failure cause of the low SCR efficiency is characterized by comprising the following steps:
checking whether the urea solution meets the requirements or not through a urea mass concentration detection module and a urea impurity detection module; the NOX sensor detection module is used for checking whether the NOX sensor works normally or not; checking whether urea can be normally injected; checking the detection results and performing corresponding treatment, and if the detection results are normal, replacing the SCR;
the working flow for checking whether the urea solution meets the requirements is as follows:
1) Checking the liquid level of the urea box, ensuring that the liquid level of the urea box is moderate, and removing excessive urea solution or insufficient urea solution;
2) Taking a small amount of urea from a urea box by using a proper tool, dripping the urea on a refractometer prism, and reading the refractive index of the urea solution by using a refractometer to measure the concentration of the urea;
3) Detecting whether the urea solution contains oil or not by using oil test paper;
the method for checking whether the NOX sensor can work normally comprises the following steps: checking whether the NOX value in the universal diagnostic instrument data stream is in a reasonable range in an idle state; if the NOX value is not in the range, replacing the NOX sensor;
wherein, check whether urea can normally spray specifically includes: removing the nozzle from the EGP, stepping on the accelerator in situ, and observing whether the urea injection system normally builds pressure and injects; if the urea injection cannot be normally performed, checking a system pressure building failure fault;
the system pressure building failure fault checking process comprises the following steps:
the diagnosis instrument is connected to ensure that the engine has no electrical appliance fault code; a transparent urea liquid inlet pipe is used, one end of the transparent liquid return pipe is connected with a urea pump, and the other end is connected with a urea barrel; igniting the engine, stepping on the accelerator in situ to ensure that the exhaust temperature reaches more than 180 ℃ and the pressure building condition is met; the diagnostic apparatus detects whether the pressure is normally built.
2. The method for troubleshooting an SCR inefficiency according to claim 1, wherein: if the concentration of the urea solution is not in the range of 30.5-34.5%, the standard urea solution is replaced.
3. The method for troubleshooting an SCR inefficiency according to claim 1, wherein: if the test paper changes color, the oil in the urea solution is indicated, the clean urea solution is replaced, and the SCR hydraulic system is cleaned.
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| CN202210583690.2A CN114991921B (en) | 2022-05-25 | 2022-05-25 | SCR (selective catalytic reduction) low-efficiency fault cause investigation method |
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| CN104880421A (en) * | 2014-02-27 | 2015-09-02 | 中国第一汽车股份有限公司 | Rapid quality evaluation method for urea reducing agent used by SCR tail gas post processing apparatus |
| CN110761881A (en) * | 2019-09-20 | 2020-02-07 | 东风商用车有限公司 | SCR efficiency diagnosis method |
| CN110767268A (en) * | 2019-09-20 | 2020-02-07 | 东风商用车有限公司 | SCR (Selective catalytic reduction) low-efficiency cause analysis method |
| CN113779494A (en) * | 2021-09-22 | 2021-12-10 | 潍柴动力股份有限公司 | SCR fault diagnosis method and device |
| CN113775397A (en) * | 2021-10-11 | 2021-12-10 | 山东理工大学 | Urea quality online detection method suitable for low heat capacity SCR (Selective catalytic reduction) catalyst |
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