Urea crystallization verification method based on vehicle user working condition

Abstract

The invention relates to the technical field of urea crystallization verification, in particular to a urea crystallization verification method based on complete vehicle user working conditions, which comprises the following steps: acquiring information of vehicles of typical vehicle types running in cities, suburbs and high speeds, and determining three operating conditions of tested vehicles: urban working conditions, suburbs working conditions and high-speed working conditions; confirming the states of the engine and the post-processing technology; the test vehicle sequentially executes the urban working condition, the suburban working condition and the high-speed working condition, crystallization test evaluation is carried out once every time one working condition is executed, the test of the next working condition is carried out if the crystallization test evaluation is passed, otherwise, the engine and post-processing technology state is confirmed again until the crystallization test evaluation corresponding to all working conditions is passed. According to the invention, the whole vehicle and crystal development verification and evaluation process is completed, a development judgment reference is formed, and the development period is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of urea crystallization verification, and particularly relates to a urea crystallization verification method based on vehicle user conditions. Background Art

[0002] With the continuous improvement of automobile exhaust emission standards, the SCR after-treatment technology is the main technical means for diesel engines to reduce NOx in exhaust gas. Its basic principle is that ammonia formed by injecting and hydrolyzing atomized urea reacts with NOx in the exhaust gas in the catalytic converter through an oxidation-reduction reaction to generate harmless nitrogen gas, meeting the regulatory requirements.

[0003] Due to the operating conditions of low running speed and frequent idling of urban logistics vehicles, the exhaust gas temperature and exhaust gas flow are both small, and it is impossible to completely bring the urea aqueous solution into the mixture gas and carry out the oxidation-reduction reaction, resulting in partial injection of urea being deposited at the mixer, forming dense urea crystals. These dense urea crystals will block the gaps between the mixer structures, causing the urea to be unable to pass through the mixer flow channel. As a result, the SCR conversion efficiency decreases and the tailpipe NOx is relatively large. At the same time, the SCR closed-loop control strategy will increase the urea injection coefficient due to the large tailpipe NOx, resulting in more urea injection and more serious crystallization. The crystallization accumulation will lead to defects such as reduced SCR efficiency, increased exhaust back pressure, and increased fuel consumption.

[0004] Currently, urea crystallization verification usually uses an engine test bench for verification, without actual vehicle application verification, and the actual vehicle environment risk is relatively large. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the existing technology and provide a urea crystallization verification method based on vehicle user conditions, which improves the vehicle and crystallization development verification and evaluation processes, forms a development judgment benchmark, and is beneficial to shortening the development cycle.

[0006] To solve the above technical problems, the present invention provides a urea crystallization verification method based on vehicle user conditions, including:

[0007] Collect vehicle information of typical vehicles running in urban, suburban, and highway areas, and determine three operating conditions of the test vehicle: urban condition, suburban condition, and highway condition;

[0008] Confirm the technical status of the engine and after-treatment;

[0009] The test vehicle sequentially executes the urban condition, suburban condition, and highway condition. After each condition is executed, a crystallization test evaluation is carried out. If the crystallization test evaluation passes, the test of the next condition is carried out. Otherwise, the technical status of the engine and after-treatment is reconfirmed until the crystallization test evaluations corresponding to all conditions pass.

[0010] In some embodiments, typical vehicle models include light commercial vehicles, which include logistics transport vehicles, passenger service vehicles, and engineering operation vehicles.

[0011] In some embodiments, the urban driving conditions of the test vehicle are as follows: maximum speed ≤ 35 km / h, average speed ≤ 25 km / h, highest gear ≤ 4th gear, for every 1 km traveled, idle in place for 30 - 60 s, and the vehicle is unloaded.

[0012] In some embodiments, the suburban driving conditions of the test vehicle are as follows: 50 km / h ≤ maximum speed ≤ 70 km / h, average speed 60 km / h, for every 3 km traveled, idle in place for 1 min, and the vehicle is fully loaded.

[0013] In some embodiments, the highway driving conditions of the test vehicle are as follows: maximum speed ≥ 90 km / h, and the vehicle is fully loaded.

[0014] In some embodiments, when the test vehicle executes any driving condition, the regeneration prohibition switch is turned on. The driving mileage of the test vehicle is N regeneration cycles corresponding to this driving condition. After each regeneration cycle is completed, the crystallization condition of the mixer, the exhaust gas aftertreatment efficiency, and the ability to completely remove crystallization during regeneration are tested.

[0015] In some embodiments, the method for testing the crystallization condition of the mixer includes: checking whether there is obvious crystallization inside the mixer and whether there is obvious crystallization at the nozzle head.

[0016] In some embodiments, the method for testing the exhaust gas aftertreatment efficiency includes: the exhaust gas temperature at the SCR inlet is 270 °C ± 10 °, operating in a steady state condition for 10 min, recording the Denox efficiency curve, and calculating the Denox efficiency decline.

[0017] In some embodiments, the method for testing the ability to completely remove crystallization during regeneration includes: starting to time after the particulate trap is heated to the operating temperature until the crystallization is completely removed, and recording the time required for complete removal of crystallization.

[0018] In some embodiments, the SCR aftertreatment system is scored based on the test results of the crystallization condition of the mixer, the exhaust gas aftertreatment efficiency, and the ability to completely remove crystallization during regeneration.

[0019] In some embodiments, the scoring criteria include:

[0020] If there is no obvious crystallization inside the mixer and at the nozzle head, the score is 100;

[0021] If there is obvious crystallization inside the mixer or at the nozzle head, the score is based on the test results of the exhaust gas aftertreatment efficiency and the ability to completely remove crystallization during regeneration:

[0022] If the Denox efficiency does not decrease and the time required to completely remove the crystallization is ≤ 5 min, the score is 80;

[0023] If the Denox efficiency decreases by ≤ 5% and the time required to completely remove the crystallization is ≤ 10 min, the score is 70;

[0024] If the Denox efficiency decreases by ≤ 10% and the time required to completely remove the crystallization is ≤ 10 min, the score is 60;

[0025] If the Denox efficiency decreases by ≤ 20% and 10 min ≤ the time required to completely remove the crystallization ≤ the time of a complete parked vehicle regeneration, the score is 40;

[0026] If the Denox efficiency decreases by > 20% and the time required to completely remove the crystallization > the time of a complete parked vehicle regeneration, the score is 20.

[0027] The beneficial effects of the present invention are as follows: The present invention formulates a complete vehicle crystallization verification process and method based on the extreme working conditions of users. By identifying the extreme operating conditions of the target vehicle model, especially the typical road spectrum of the working conditions of urban logistics users, this road spectrum is extracted to the test vehicle for crystallization verification. Through measures such as setting specific operating conditions, durability mileage, and crystallization judgment methods, the implementation and effectiveness of the verification method are guaranteed, and risks such as crystallization complaints and market claims existing at the client side are solved. Description of the Drawings

[0028] Figure 1 It is a flowchart of the present invention. Detailed Embodiments

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0030] As Figure 1 shown, the present invention provides a urea crystallization verification method based on the vehicle user working conditions, including:

[0031] S1. Collect the vehicle information of a typical vehicle model when driving in the city, suburb and highway, and determine three operating conditions of the test vehicle: urban condition, suburban condition, and highway condition;

[0032] In some embodiments, the typical vehicle model includes light commercial vehicles, and light commercial vehicles include logistics transport vehicles, passenger service vehicles (such as shuttle buses, school buses and tourist buses, etc.), engineering operation vehicles, etc. The typical vehicle model can select the corresponding vehicle model according to the test object.

[0033] In some embodiments, the urban driving conditions of the test vehicle are as follows: maximum speed ≤ 35 km / h, average speed ≤ 25 km / h, highest gear ≤ 4th gear, for every 1 km traveled, idling in place for 30 - 60 s, and the vehicle is unloaded.

[0034] The suburban driving conditions of the test vehicle are as follows: 50 km / h ≤ maximum speed ≤ 70 km / h, average speed 60 km / h, for every 3 km traveled, idling in place for 1 min, and the vehicle is fully loaded.

[0035] The highway driving conditions of the test vehicle are as follows: maximum speed ≥ 90 km / h, and the vehicle is fully loaded.

[0036] By collecting data on the crystallization - prone driving conditions of in - use vehicles, the corresponding most - stringent crystallization conditions are identified, and typical crystallization test boundaries based on actual users are established, covering three types of driving conditions: urban, suburban, and highway. The test conditions such as vehicle speed, load, and driving requirements for each driving condition are clarified.

[0037] The test vehicle of the present invention is a light - duty diesel vehicle.

[0038] S2. Confirm the technical status of the engine and after - treatment;

[0039] Confirm that the engine performance meets the target requirements, the emission results meet the regulatory requirements, the bench - top control boundary of crystallization is frozen, the hardware status of the after - treatment meets the requirements, and the vehicle load and operating status meet the test requirements. Implement regeneration and check whether the crystallization of the mixer is cleared, and weigh the unloaded mixer.

[0040] S3. The test vehicle sequentially executes the urban driving condition, suburban driving condition, and highway driving condition. After each driving condition is completed, a crystallization test evaluation is carried out. If the crystallization test evaluation passes, the test of the next driving condition is carried out; otherwise, the technical status of the engine and after - treatment is confirmed again until all crystallization test evaluations corresponding to all driving conditions pass.

[0041] In some embodiments, when the test vehicle executes any driving condition, the regeneration prohibition switch is turned on to prohibit regeneration. The driving mileage of the test vehicle is two regeneration cycles corresponding to that driving condition. For example, if the regeneration mileage in the urban driving condition is 800 km, then the driving mileage of the test vehicle in the urban driving condition is 1600 km; if the regeneration mileage in the suburban driving condition is 1000 km, then the driving mileage of the test vehicle in the urban driving condition is 2000 km; if the regeneration mileage in the highway driving condition is 1200 km, then the driving mileage of the test vehicle in the urban driving condition is 2400 km. After each regeneration cycle is completed, the crystallization situation of the mixer, the tail - gas after - treatment efficiency, and the ability of regeneration to completely remove crystallization are tested.

[0042] Among them, the methods for testing the crystallization situation of the mixer include: checking whether there is obvious crystallization at the nozzle head, disassembling the nozzle, checking whether there is obvious crystallization inside the mixer, taking pictures of the crystallization morphology of the mixer, weighing and comparing the crystallization weight increment of each disassembled mixer monomer, and recording.

[0043] The methods for testing the tail gas post-treatment efficiency include: the exhaust gas temperature at the SCR inlet is 270°C ± 10°, operating under steady-state conditions for 10 minutes, recording the Denox efficiency curve, and calculating the Denox efficiency decline situation.

[0044] The methods for testing the ability of regeneration to completely remove crystallization include: starting timing after the particulate trap is heated to the operating temperature until the crystallization is completely removed, and recording the time required for complete removal of the crystallization.

[0045] Score the SCR post-treatment system based on the test results of the crystallization situation of the mixer, the tail gas post-treatment efficiency, and the ability of regeneration to completely remove crystallization.

[0046] The crystallization situation of the mixer, the tail gas post-treatment efficiency, and the ability of regeneration to completely remove crystallization cannot evaluate the SCR post-treatment system alone. Therefore, it is necessary to combine the test results of the three aspects for evaluation to ensure that the score is referenceable.

[0047] In some embodiments, the scoring criteria include:

[0048] If there is no obvious crystallization inside the mixer and at the nozzle head, the score is 100;

[0049] If there is obvious crystallization inside the mixer or at the nozzle head, score according to the test results of the tail gas post-treatment efficiency and the ability of regeneration to completely remove crystallization:

[0050] If the Denox efficiency does not decline and the time required for complete removal of crystallization ≤ 5 minutes, the score is 80;

[0051] If the Denox efficiency decline ≤ 5%, and the time required for complete removal of crystallization ≤ 10 minutes, the score is 70;

[0052] If the Denox efficiency decline ≤ 10%, and the time required for complete removal of crystallization ≤ 10 minutes, the score is 60;

[0053] If the Denox efficiency decline ≤ 20%, and 10 minutes ≤ the time required for complete removal of crystallization ≤ one complete parking regeneration time, the score is 40;

[0054] If the Denox efficiency decline > 20%, and the time required for complete removal of crystallization > one complete parking regeneration time, the score is 20.

[0055] If the score is not less than 60, it means that the crystallization test evaluation corresponding to this working condition passes, and the test evaluation of the next working condition can be carried out.

[0056] Specifically, it is shown in the following table:

[0057]

[0058] Through the analysis of the impact on user use after crystallization formation, the present invention establishes a three-element crystallization evaluation method, scores from three evaluation dimensions of the presence or absence of crystallization amount, the impact on Denox efficiency, and the ability to completely remove crystallization during regeneration, and the scoring result can accurately reflect whether the SCR after-treatment system meets the requirements.

[0059] The present invention solves the market problems of customer vehicle crystallization and related OBD failures; improves the vehicle and crystallization development verification and evaluation processes, forms a development judgment benchmark, and is beneficial to shortening the development cycle.

[0060] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A urea crystallization verification method based on the vehicle user working condition, characterized in that, Including: Collect vehicle information of typical vehicle models during urban, suburban, and highway driving, and determine three operating conditions for the test vehicle: urban condition, suburban condition, and highway condition; Confirm the technical status of the engine and after-treatment; The test vehicle sequentially executes the urban condition, suburban condition, and highway condition. After each condition is executed, a crystallization test evaluation is carried out. If the crystallization test evaluation passes, the test of the next condition is carried out. Otherwise, the technical status of the engine and after-treatment is reconfirmed until the crystallization test evaluations corresponding to all conditions pass.

2. The urea crystallization verification method based on the vehicle user working condition according to claim 1, wherein, The urban condition of the test vehicle is: maximum speed ≤ 35 km / h, average speed ≤ 25 km / h, highest gear ≤ 4th gear, idle in place for 30 - 60 s every 1 km traveled, and the vehicle is unloaded.

3. The urea crystallization verification method based on the vehicle user working conditions according to claim 1, wherein The suburban condition of the test vehicle is: 50 km / h ≤ maximum speed ≤ 70 km / h, average speed 60 km / h, idle in place for 1 min every 3 km traveled, and the vehicle is fully loaded.

4. The urea crystallization verification method based on the vehicle user working conditions according to claim 1, characterized in that, The highway condition of the test vehicle is: maximum speed ≥ 90 km / h, and the vehicle is fully loaded.

5. The urea crystallization verification method based on the vehicle user working conditions according to any one of claims 1 to 4, characterized in that, When the test vehicle executes any condition, turn on the regeneration prohibition switch. The driving mileage of the test vehicle is N regeneration cycles corresponding to that condition. After each regeneration cycle is completed, the crystallization condition of the mixer, the exhaust after-treatment efficiency, and the ability of regeneration to completely remove crystallization are tested.

6. The urea crystallization verification method based on the vehicle user working conditions according to claim 5, characterized in that, The methods for testing the crystallization condition of the mixer include: checking whether there is obvious crystallization inside the mixer and at the nozzle head.

7. The urea crystallization verification method based on the vehicle user working conditions according to claim 5, wherein, The methods for testing the exhaust after-treatment efficiency include: the exhaust temperature at the SCR inlet is 270 °C ± 10 °, operating in a steady-state condition for 10 min, recording the Denox efficiency curve, and calculating the Denox efficiency drop.

8. The urea crystallization verification method based on the vehicle user working conditions according to claim 5, wherein The methods for testing the ability of regeneration to completely remove crystallization include: start timing after the particulate trap is heated to the operating temperature until the crystallization is completely removed, and record the time required for complete crystallization removal.

9. The urea crystallization verification method based on the vehicle user working conditions according to claim 5, characterized in that Score the SCR after-treatment system based on the test results of the crystallization condition of the mixer, the exhaust after-treatment efficiency, and the ability of regeneration to completely remove crystallization.

10. The urea crystallization verification method based on the vehicle user working conditions according to claim 9, wherein, The scoring criteria include: If there is no obvious crystallization inside the mixer and at the nozzle head, the score is 100; If there is obvious crystallization inside the mixer or at the nozzle head, score according to the test results of the exhaust after-treatment efficiency and the ability of regeneration to completely remove crystallization: If the Denox efficiency does not drop and the time required for complete crystallization removal ≤ 5 min, the score is 80; If the Denox efficiency drops ≤ 5%, and the time required for complete crystallization removal ≤ 10 min, the score is 70; If the Denox efficiency drops ≤ 10%, and the time required for complete crystallization removal ≤ 10 min, the score is 60; If the Denox efficiency drops ≤ 20%, and 10 min ≤ the time required for complete crystallization removal ≤ one complete parked vehicle regeneration time, the score is 40; If the Denox efficiency drops > 20%, and the time required for complete crystallization removal > one complete parked vehicle regeneration time, the score is 20.

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