Method and device for detecting abnormal urea concentration

Abstract

The application provides a urea concentration anomaly detection method and device. After detecting that the urea concentration measurement value decreases, the urea injection amount correction factor is first frozen to avoid the influence of the monitoring result caused by the excessive injection of urea after the decrease of the urea concentration. Further, after the urea concentration measurement value maintains the decrease for a certain time, the specific emission of the engine is calculated, and whether the urea concentration is abnormal is determined according to the change of the specific emission at this time. The scheme uses the specific emission of the engine to determine whether the urea concentration is abnormal. The specific emission can truly reflect the real situation of the engine emission, and further, the specific emission can also reflect the real situation of the urea concentration. Therefore, the scheme can effectively identify the influence of the bubbles in the urea tank on the urea concentration measurement value, and effectively reduce the false positive rate of the urea concentration anomaly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engine aftertreatment systems, and particularly relates to a urea concentration abnormality detection method and device. BACKGROUND

[0002] Diesel engine emission regulations have strict requirements for nitrogen oxide (NOx) emissions, and the selective catalytic reduction (SCR) process is usually used to treat NOx, that is, ammonia or urea is sprayed to reduce NOx in exhaust gas into N2 and H2O under the action of a catalyst.

[0003] Unqualified urea concentration will cause NOx emissions to exceed the standard, and urea quality sensors are generally needed to measure urea concentration in real time. At present, the most widely used sensor is based on the principle of acoustics. According to the principle that the speed of ultrasonic waves is different in different media, the time difference between the emission and reflection of sound waves in a fixed distance is measured, the sound intensity of sound waves in the liquid is calculated, and the concentration of urea solution is obtained. In actual application, due to reasons such as vehicle driving bumping, urea backflow splashing into the urea tank, and urea tank temperature change, a large number of bubbles appear in the urea tank, the bubbles adhere to the surface of the urea quality sensor probe, and the urea concentration measurement is inaccurate.

[0004] How to identify whether the abnormal urea concentration measured by the urea quality sensor is caused by bubbles or urea quality problems is a difficult problem in the industry at present. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a urea concentration abnormality detection method and device to solve the above problems, and the disclosed technical solution is as follows:

[0006] In a first aspect, the present application provides a urea concentration abnormality detection method, comprising:

[0007] When the urea concentration is detected to be lower than a first concentration threshold, the value of a urea injection amount correction factor is determined based on the urea concentration and is frozen;

[0008] After detecting that the duration for which the urea concentration is lower than the first concentration threshold is greater than or equal to a time threshold, the specific emission value of the engine is determined, and the time threshold is the time required to eliminate the ammonia storage affecting factor;

[0009] If the specific emission value is greater than or equal to a specific emission limit value, it is determined that the urea concentration is abnormal;

[0010] If the specific emission value is less than the specific emission limit value, it is determined that the urea concentration is normal.

[0011] Optionally, the method further comprises:

[0012] calculating an average of the urea concentrations detected in a preset time period before the urea concentration decreases, to obtain an average urea concentration;

[0013] searching for a target value of the urea injection amount correction factor in the correction factor table that matches the average urea concentration;

[0014] fixing the urea injection amount correction factor as the target value obtained by searching the table.

[0015] Optionally, the method further comprises:

[0016] obtaining a temperature value upstream of the SCR;

[0017] searching for a time in the temperature-time table that matches the temperature value upstream of the SCR, and determining the time as the time threshold.

[0018] Optionally, the method further comprises:

[0019] calculating an integral value of the NOx measurement value upstream of the SCR and the specific emission value in the same time period;

[0020] if the integral value is greater than or equal to a first limit value, determining the specific emission value of the engine as the specific emission value of the NOx downstream of the SCR calculated in the time period in which the NOx measurement value upstream of the SCR is integrated.

[0021] Optionally, the method further comprises:

[0022] if the integral value is less than the first limit value, continuing to calculate the integral value of the NOx measurement value upstream of the SCR and the specific emission value of the NOx downstream of the SCR in the next time period.

[0023] Optionally, the method further comprises:

[0024] obtaining the NOx measurement value upstream of the SCR and the NOx measurement value downstream of the SCR collected in the same time period;

[0025] calculating the integral value of the NOx measurement value upstream of the SCR based on each of the NOx measurement values upstream of the SCR;

[0026] calculating the specific emission value based on each of the NOx measurement values downstream of the SCR.

[0027] Optionally, after determining that the urea concentration is abnormal, the method further comprises: outputting prompt information of the urea concentration being abnormal.

[0028] Optionally, the method further comprises:

[0029] If the duration that the urea concentration is lower than the first concentration threshold value is less than the time threshold value, the freezing of the value of the urea injection amount correction factor is released.

[0030] In a second aspect, the present application further provides a urea concentration abnormality detection device, comprising:

[0031] A freezing module is configured to determine a value of a urea injection amount correction factor based on the urea concentration and freeze the value when it is detected that the urea concentration is lower than a first concentration threshold value;

[0032] A specific emission determination module is configured to determine a specific emission value of the engine when it is detected that the duration that the urea concentration is lower than the first concentration threshold value is greater than or equal to a time threshold value, the time threshold value being a time required to eliminate an ammonia storage effect factor;

[0033] A urea concentration abnormality determination module is configured to determine that the urea concentration is abnormal when the specific emission value is greater than or equal to a specific emission limit value;

[0034] A urea concentration normality determination module is configured to determine that the urea concentration is normal when the specific emission value is less than the specific emission limit value.

[0035] In a third aspect, the present application further provides an electronic device, comprising a memory and a controller, the memory storing program instructions, and the controller executing the program instructions to implement the urea concentration abnormality detection method of any one of the first aspect.

[0036] In a fourth aspect, the present application further provides a readable storage medium storing a computer program, characterized in that the computer program is executed by a processor to implement the urea concentration abnormality detection method of any one of the first aspect.

[0037] The urea concentration abnormality detection method provided by the embodiment uses the specific emission of the engine to determine whether the urea concentration is abnormal. The specific emission can truly reflect the real situation of the engine emission, and further, the specific emission can also reflect the real situation of the urea concentration. Therefore, the scheme can effectively identify the influence of the bubbles in the urea tank on the urea concentration measurement value, and effectively reduce the false positive rate of the urea concentration abnormality. Moreover, the scheme freezes the urea injection amount correction factor after detecting that the urea concentration measurement value is reduced, thereby avoiding the influence of the excessive injection of urea on the monitoring result after the urea concentration is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0039] Figure 1 is a structural schematic diagram of a post-processing system provided by an embodiment of the present application;

[0040] Figure 2 is a flow of a urea concentration abnormality detection method provided by an embodiment of the present application;

[0041] Figure 3 is a flow of another urea concentration abnormality detection method provided by an embodiment of the present application;

[0042] Figure 4 is a curve diagram of urea concentration and engine tail gas emission ratio;

[0043] Figure 5 is another curve diagram of urea concentration and engine tail gas emission ratio;

[0044] Figure 6 is a structural schematic diagram of a urea concentration abnormality detection device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0046] Please refer to Figure 1 , which shows a structural schematic diagram of a post-processing system provided by an embodiment of the present application. As shown in Figure 1 , the system includes an engine, an oxidation catalytic converter (Diesel Oxidation Catalyst, DOC), a diesel particulate filter (Diesel Particulate Filter, DPF), an SCR, a urea tank, and a urea supply module. The arrows in the figure represent the direction of engine exhaust gas.

[0047] The urea tank is provided with a urea quality sensor, the output end of the SCR is provided with a NOx sensor (which can be referred to as a SCR downstream NOx sensor), and the input end of the DOC is provided with a NOx sensor (which can be referred to as a SCR upstream NOx sensor) and a temperature sensor (which can be referred to as a SCR upstream temperature sensor).

[0048] The urea quality sensor is used to measure the concentration of the urea solution in the urea tank, i.e., the urea concentration.

[0049] The SCR upstream NOx sensor is used to measure the content of NOx in the gas output by the DOC.

[0050] The SCR downstream NOx sensor is used to measure the content of NOx in the gas discharged by the SCR.

[0051] The SCR upstream temperature sensor is used to measure the temperature of the exhaust gas discharged by the engine.

[0052] In addition, the system further includes a controller (e.g., an ECU), and the measurement values obtained by the sensors are transmitted to the controller, and the controller performs the urea concentration abnormality detection method provided in the present application based on the received measurement values.

[0053] The urea concentration abnormality detection method provided in the present application will be described in detail below. Figure 2 The urea concentration abnormality detection method provided in the present application will be described in detail below. Figure 2 As shown in the figure, the method includes the following steps:

[0054] S101, when it is detected that the urea concentration is lower than a first concentration threshold, determining the value of the urea injection amount correction factor based on the urea concentration and freezing the value.

[0055] It is determined whether the urea concentration measured by the urea quality sensor is lower than a first concentration threshold (e.g., 25%). If the urea concentration decreases by 3% within 1s and the urea concentration is less than 25%, it is determined that the urea concentration has a significant decrease.

[0056] The function of the urea injection amount correction factor is to correct the urea injection amount output by the controller. The correction factor table records the mapping relationship between the urea concentration and the urea injection amount correction factor.

[0057] If the measured urea concentration has a significant decrease, the corresponding urea injection amount correction factor value is obtained based on the urea concentration by searching the correction factor table, and the value is frozen to prevent the urea concentration from being reduced and the urea injection amount from being increased, which affects the monitoring result.

[0058] S102, after it is detected that the duration for which the urea concentration is lower than the first concentration threshold is greater than or equal to a time threshold, calculating the specific emission value of the engine.

[0059] In an exemplary embodiment, the time threshold T is determined by the ammonia storage in the SCR, and since the ammonia storage in the SCR has an impact on the calculation of the specific emission, the impact of the ammonia storage needs to be eliminated. T is determined based on the temperature-time table according to the temperature upstream of the SCR. The ammonia storage in the SCR is strongly related to the temperature of the SCR, in general, the higher the temperature of the SCR, the lower the ammonia storage, and the smaller the time T; conversely, the lower the temperature of the SCR, the more the ammonia storage, and the larger the time T.

[0060] wherein the temperature upstream of the SCR is the temperature measured by the temperature sensor upstream of the SCR.

[0061] If the duration of the urea concentration value being the low concentration (e.g. less than 25%) is greater than or equal to the time T, it is considered that the ammonia storage in the SCR affecting the monitoring result is consumed, and then the specific emission of the engine can be calculated.

[0062] The specific emission of the engine is calculated by using the following formula 1:

[0063]

[0064] In the formula 1, E is the specific emission of the engine, g / kWh; m NOxDs is the measured value of the NOx sensor downstream of the SCR, g / s; T is the engine torque, Nm; and n is the engine speed, r / min.

[0065] S103, determining whether the specific emission value is less than the specific emission limit value, if yes, performing S104; if no, performing S105.

[0066] The specific emission limit value can be the value specified by the diesel engine emission regulation, such as 0.69 g / kWh.

[0067] S104, determining that the urea concentration is normal.

[0068] If the specific emission value is less than the specific emission limit value, it indicates that the emission amount of NOx meets the regulation, and further indicates that the urea concentration is normal. The abnormal urea concentration measured by the urea quality sensor can be caused by the air bubble of the urea quality sensor probe.

[0069] S105, determining that the urea concentration is abnormal.

[0070] If the specific emission value is greater than or equal to the specific emission limit value, it indicates that the emission amount of NOx does not meet the regulation, and further indicates that the urea concentration is abnormal.

[0071] The prior art determines whether the urea concentration is abnormal by using the NOx conversion efficiency, and the NOx conversion efficiency is a relative concept. The diesel engine emission regulation requires that the NOx emission at the outlet of the SCR cannot exceed 0.69 g / kWh.

[0072] For example, if the SCR inlet NOx content is 8 g / kWh, the SCR outlet NOx is 0.4 g / kWh, and the NOx conversion efficiency is 95%; if the SCR inlet NOx is 2 g / kWh, the SCR outlet NOx is 0.4 g / kWh, and the NOx conversion efficiency is 80%; the NOx conversion efficiency is 80% when the urea concentration is determined to be abnormal. Obviously, the NOx of the SCR outlet in the two cases is 0.4 g / kWh, but the NOx conversion efficiencies of the two are different. Therefore, the engine specific emission is more accurate in determining the abnormality of the urea concentration.

[0073] Furthermore, after detecting that the urea concentration measurement value decreases, the embodiment first freezes the urea injection amount correction factor to avoid the influence of excessive urea injection on the monitoring result after the urea concentration decreases.

[0074] The urea concentration abnormality detection method provided by the embodiment uses the engine specific emission to determine whether the urea concentration is abnormal. The specific emission can truly reflect the real situation of engine emission, and further, the specific emission can also reflect the real situation of the urea concentration. Therefore, the scheme can effectively identify the influence of the air bubbles in the urea tank on the urea concentration measurement value, and effectively reduce the false positive rate of urea concentration abnormality. Furthermore, after detecting that the urea concentration measurement value decreases, the scheme first freezes the urea injection amount correction factor to avoid the influence of excessive urea injection on the monitoring result after the urea concentration decreases.

[0075] Please refer to Figure 3 , which shows a flowchart of another urea concentration abnormality detection method provided by the embodiment of the application. As shown in Figure 3 , the method can include the following steps:

[0076] S201, the vehicle runs the engine.

[0077] S202, determine whether the urea concentration measured by the urea quality sensor is significantly reduced; if yes, execute S203; if not, continue to monitor the urea concentration, that is, continue to execute S202.

[0078] In an exemplary embodiment, if the urea concentration decreases by more than a certain value, such as 3%, in a unit of time, and the urea concentration is lower than a first threshold value (such as 25%), it is determined that the urea concentration is reduced. For example, if the urea concentration decreases by 3% in 1 s and the urea concentration is less than 25%, it is determined that the urea concentration is significantly reduced.

[0079] S203, determine the urea injection amount correction factor value based on the urea concentration and freeze the value.

[0080] In an exemplary embodiment, the determination process of the urea injection amount correction factor is as follows:

[0081] (1) Calculate the average of each urea concentration detected within a preset time period before the urea concentration decreases to obtain a urea concentration average;

[0082] (2) Find the target value of the urea injection amount correction factor in the correction factor table that matches the urea concentration average.

[0083] For example, urea concentration measurement values of the urea quality sensor are collected at intervals (e.g., 1 s) during vehicle operation, and the urea concentration values are stored in an array Xi. When the array is full (e.g., more than 10 dimensions), data processing is performed using the FIFO principle (i.e., first-in, first-out principle) to move the storage. If a significant decrease in urea concentration is detected (e.g., a decrease of 3% within 1 s and a measured concentration below 25%), collection is stopped, and the average of each concentration value in the original array Xi is calculated. The urea concentration average is taken as the basic urea concentration value, and the urea injection amount correction factor a is obtained by searching the correction factor table.

[0084] Using the average of the urea concentration values as the basic urea concentration value can avoid the influence of abnormal points collected due to fluctuations in urea concentration on the calculation results.

[0085] In addition, if the collected urea concentration values return to normal, they are re-collected and stored in the array Xi. Among them, the urea concentration values returning to normal means that a plurality of (e.g., 5) continuously collected urea concentration measurement values are greater than a second threshold value (e.g., 30%), i.e., the urea concentration values collected for a continuous 5 s time are all greater than 30% to determine that the urea concentration has returned to normal.

[0086] S204, determine whether the duration of the urea concentration measurement value being low concentration exceeds a time threshold; if not, execute S205; if yes, execute S206.

[0087] The time threshold T is determined by the ammonia storage in the SCR, please refer to the related content of S102, which will not be repeated here.

[0088] If the duration of the urea concentration value being low concentration (e.g., less than 25%) is greater than or equal to the time T, it is considered that the ammonia storage affecting the monitoring result in the SCR is consumed, and the specific emission of the engine can be calculated next, i.e., continue to execute S206. If the duration of the urea concentration value being low concentration is less than the time T, it is considered that the measurement value of the urea quality sensor has returned to normal, and the freezing of the urea injection amount correction factor is released, i.e., continue to execute step S205.

[0089] S205, release the freezing of the urea injection amount correction factor.

[0090] S206, calculate the integral value of the NOx measurement value upstream of the SCR within a period of time, and calculate the specific emission value of the engine tail exhaust.

[0091] In an exemplary embodiment, before calculating the engine specific emission, it is determined whether the following calculation conditions are met: for example, the upstream / downstream NOx sensor of the SCR is working normally; the urea is injected normally and there is no pipeline blockage fault; the engine emission is normal before the urea concentration is reduced, etc. The controller has the above-mentioned parameter monitoring strategy, which receives relevant information and calculates.

[0092] After it is determined that the above-mentioned calculation conditions are met, the integral value of the NOx measurement value measured by the upstream NOx sensor of the SCR in a period of time is calculated, and the specific emission of the engine in the period of time is calculated.

[0093] Wherein, the integral value of the upstream NOx of the SCR is calculated by the formula ∫m NOxUs d t The integral value of the upstream NOx of the SCR is calculated by the formula ∫m NOxUs The specific emission is calculated by the above-mentioned formula 1

[0094] Wherein, the integral value of the upstream NOx measurement value is calculated using the upstream NOx measurement value of the SCR, and the downstream NOx measurement value of the SCR is collected in the same period of time.

[0095] S207, it is determined whether the integral value of the upstream NOx measurement value is greater than or equal to the first limit value; if yes, S108 is executed; if no, S106 is returned to execute.

[0096] In the embodiment of the application, the integral value of the upstream NOx measurement value is the judgment condition for calculating the engine specific emission, the specific emission refers to the ratio of the NOx content downstream of the SCR to the engine work amount during the engine operation, and when the upstream NOx content of the SCR is particularly small, the error of the calculated specific emission will be very large, therefore, the engine specific emission is calculated while the upstream NOx measurement value of the SCR is integrated. When it is determined that the integral value of the upstream NOx measurement value is greater than the limit value, it is considered that the specific emission calculated in this integral process has higher reliability.

[0097] For example, if the integral value of the upstream NOx measurement value is greater than or equal to the first limit value, it indicates that the upstream NOx content of the SCR is relatively large, and the specific emission calculated in this process has higher reliability. The first limit value is related to the engine model and the integral time, for example, the first limit value in the example can be 15g

[0098] S208, whether the specific emission calculated in the process of calculating the integral value of the upstream NOx measurement value is greater than or equal to the specific emission limit value; if no, S109 is executed; if yes, S110 is executed.

[0099] If the integral of the NOx measurement upstream of the SCR is greater than or equal to the first limit value, it is determined whether the specific emission value calculated in the process of calculating the upstream NOx integral value exceeds the regulatory limit value in a short time, such as 15 min, and is greater than 0.69 g / kWh.

[0100] S209, it is determined that the vehicle emission is normal and the urea concentration is normal.

[0101] If the engine specific emission does not exceed the regulatory limit value, it indicates that the abnormal urea concentration measurement may be caused by bubbles on the probe surface of the urea quality sensor, rather than a real abnormality in the urea concentration.

[0102] S210, it is determined that the urea concentration is abnormal, and a prompt information of the abnormal urea concentration is output.

[0103] If the engine specific emission exceeds the regulatory limit value, it indicates that the urea concentration is indeed abnormal, and at this time, a prompt information of the abnormal urea concentration can be output, for example, the prompt information can be at least one of light, text prompt information, sound prompt of the center console. The prompt information is output to remind the driver to replace the urea.

[0104] Please refer to Figure 4 , which shows a curve diagram of urea concentration and engine tail emission specific emission, the horizontal coordinate represents the vehicle running time, the time unit is h (hour), and the vertical coordinate is the specific emission and the urea concentration.

[0105] As shown in Figure 4 , curve 1 is the urea concentration curve measured by the urea quality sensor, the urea concentration suddenly decreases at t1, and remains low until t2, then the engine specific emission is calculated from t2.

[0106] Curve 2 is the engine specific emission curve, which is lower than the specific emission limit value from the start of the engine until t2, if the specific emission starts to rise and exceeds the specific emission limit value from t2, it is determined that the urea concentration is abnormal. If the specific emission does not rise significantly from t2, it is determined that the urea concentration is normal.

[0107] Please refer to Figure 5 , which shows another curve diagram of urea concentration and specific emission, wherein the horizontal coordinate is the running time, and the vertical coordinate is the urea concentration and the specific emission, respectively.

[0108] As shown in Figure 5 , the curve on the upper side of the figure is the urea concentration curve, and the lower curve is the specific emission curve, wherein the urea concentration decreases significantly at t1, and the urea concentration fluctuates, and the specific emission fluctuates but does not exceed the specific emission limit value, therefore, it is determined that the urea concentration is normal, which may be caused by the bubbles affecting the probe of the urea quality sensor, resulting in abnormal urea concentration measurement.

[0109] The urea concentration abnormality detection method provided by the embodiment avoids the influence of excessive urea injection on the monitoring result after the urea concentration measurement value is detected to decrease. Further, after the urea concentration measurement value is determined to maintain the decrease for a certain time, the specific emission of the engine is calculated, and whether the urea concentration is abnormal is determined according to the change of the specific emission at this time. This scheme uses the specific emission of the engine to determine whether the urea concentration is abnormal. The specific emission can truly reflect the real situation of the engine emission, and further, the specific emission can also reflect the real situation of the urea concentration. Therefore, this scheme can effectively identify the influence of the bubbles in the urea tank on the urea concentration measurement value, and effectively reduce the false positive rate of urea concentration abnormality.

[0110] Corresponding to the urea concentration abnormality detection method embodiment described above, the embodiment of the application also provides a urea concentration abnormality detection device embodiment, as shown in Figure 6 The urea concentration abnormality detection device can include:

[0111] The freezing module 101 is configured to determine the value of the urea injection amount correction factor based on the urea concentration and freeze the value when the urea concentration is detected to be lower than the first concentration threshold.

[0112] In an exemplary embodiment, the freezing module 101 is specifically configured to:

[0113] Calculate the average value of each urea concentration detected within a preset time period before the urea concentration decreases to obtain a urea concentration average value;

[0114] Search for a target value of the urea injection amount correction factor matching the urea concentration average value in the correction factor table;

[0115] Fix the urea injection amount correction factor as the target value obtained by searching the table.

[0116] The specific emission determination module 102 is configured to determine the specific emission value of the engine when the duration that the urea concentration is detected to be lower than the first concentration threshold is greater than or equal to a time threshold, the time threshold being the time required to eliminate the ammonia storage influence factor.

[0117] In an exemplary embodiment, the specific emission determination module 102 is specifically configured to:

[0118] Calculate the integral value of the SCR upstream NOx measurement value and the specific emission value within the same time period when the duration that the urea concentration is detected to be lower than the first concentration threshold is greater than or equal to the time threshold;

[0119] If the integral value is greater than or equal to the first limit value, the specific emission value calculated in the time period during which the NOx measurement value upstream of the SCR is integrated is determined as the specific emission value of the engine.

[0120] The process of calculating the integral value of the NOx measurement value upstream of the SCR and the specific emission value in the same time period comprises:

[0121] The NOx measurement value upstream of the SCR and the NOx measurement value upstream of the SCR collected in the same time period are obtained.

[0122] The integral value of the NOx measurement value upstream of the SCR is calculated based on each of the NOx measurement values upstream of the SCR.

[0123] The specific emission value is calculated based on each of the NOx measurement values downstream of the SCR.

[0124] The urea concentration abnormality determination module 103 is configured to determine that the urea concentration is abnormal when the specific emission value is greater than or equal to a specific emission limit value.

[0125] The urea concentration normality determination module 104 is configured to determine that the urea concentration is normal when the specific emission value is less than the specific emission limit value.

[0126] The urea concentration abnormality detection device provided by the embodiment can determine whether the urea concentration is abnormal by using the specific emission of the engine. The specific emission can truly reflect the real situation of the engine emission, and further, the specific emission can also reflect the real situation of the urea concentration. Therefore, the scheme can effectively identify the influence of the air bubbles in the urea tank on the urea concentration measurement value, and effectively reduce the false positive rate of the urea concentration abnormality. Moreover, after detecting that the urea concentration measurement value is reduced, the urea injection amount correction factor is first frozen, so as to avoid the influence of the excessive urea injection on the monitoring result after the urea concentration is reduced.

[0127] In addition, the present application provides an electronic device comprising a controller and a memory having a program stored therein and executable on the controller. The controller implements the urea concentration abnormality detection method described above when executing the program stored in the memory.

[0128] The electronic device herein can be a server, a PC, a PAD, a mobile phone, an ECU (Electronic Control Unit), a VCU (Vehicle Control Unit), an MCU (Micro Controller Unit), an HCU (Hybrid Control Unit), etc.

[0129] The application also provides a diesel engine exhaust aftertreatment system, which can include a structure as shown in Figure 1 The controller can execute the urea concentration abnormality detection method described above.

[0130] For each of the method embodiments described above, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the order of the described actions, because according to the present application, certain steps can be performed in other order or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily necessary for the present application.

[0131] It should be noted that the technical features described in each embodiment of the present application can be replaced or combined with each other, and each embodiment focuses on the difference from other embodiments, and the same and similar parts between each embodiment can be referred to each other. For device embodiments, since they are basically similar to method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiment.

[0132] The steps in the method of each embodiment of the present application can be adjusted, combined and deleted according to actual needs.

[0133] The modules and sub-modules in the device and terminal in each embodiment of the present application can be combined, divided and deleted according to actual needs.

[0134] In several embodiments provided by the present application, it should be understood that the disclosed terminal, device and method can be implemented by other ways. For example, the terminal embodiments described above are only schematic, for example, the division of modules or sub-modules is only a logical function division, and there can be another division way in actual implementation, for example, a plurality of sub-modules or modules can be combined or integrated into another module, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed mutually can be indirect coupling or communication connection through some interface, device or module, and can be electrical, mechanical or other forms.

[0135] The modules or sub-modules described as separate components can or can not be physically separate, and the components of the modules or sub-modules can or can not be physical modules or sub-modules, that is, they can be located in one place, or can be distributed to multiple network modules or sub-modules. Some or all modules or sub-modules can be selected according to actual needs to achieve the purpose of the present embodiment.

[0136] In addition, each functional module or sub-module in each embodiment of the present application can be integrated in one processing module, or each module or sub-module can exist physically alone, or two or more modules or sub-modules can be integrated in one module. The integrated module or sub-module can be realized in the form of hardware or in the form of software functional module or sub-module.

[0137] Finally, it should be noted that in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0138] The above description of disclosed embodiments enables a person skilled in the art to implement or use the invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features disclosed herein.

[0139] The above description is only the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A urea concentration abnormality detection method characterized by comprising: The method comprises the following steps: determining a value of a urea injection amount correction factor based on the urea concentration and freezing the value when the urea concentration is detected to be lower than a first concentration threshold value; determining a specific emission value of the engine after detecting that the urea concentration is lower than the first concentration threshold value for a duration greater than or equal to a time threshold value, the time threshold value being a time required to eliminate an ammonia storage impact factor; determining that the urea concentration is abnormal if the specific emission value is greater than or equal to a specific emission limit value; determining that the urea concentration is normal if the specific emission value is less than the specific emission limit value; wherein the calculation formula of the specific emission value is: wherein is the specific emission value of the engine, g / kWh; is the SCR downstream NOx sensor measurement, g / s; is the engine torque, Nm; is the engine speed, r / min; wherein the determination of the specific emission value of the engine comprises: calculating an integral value of an SCR upstream NOx measurement value and a specific emission value of an SCR downstream NOx in the same time period; determining the specific emission value of the engine as the specific emission value of the SCR downstream NOx calculated in the time period during which the integral value of the SCR upstream NOx measurement value is integrated if the integral value is greater than or equal to a first limit value; calculating an integral value of an SCR upstream NOx measurement value and a specific emission value of an SCR downstream NOx in the next time period if the integral value is less than the first limit value.

2. The method of claim 1, wherein, The method further comprises the following steps: calculating an average value of each urea concentration detected in a preset time period before the urea concentration decreases to obtain a urea concentration average value; looking up a target value of a urea injection amount correction factor matching the urea concentration average value in a correction factor table; fixing the urea injection amount correction factor as the target value obtained by the looking up.

3. The method according to claim 1 or 2, characterized in that, The determination process of the time threshold value comprises the following steps: obtaining an SCR upstream temperature value; looking up a time matching the SCR upstream temperature value in a temperature-time table to determine the time threshold value.

4. The method of claim 1, wherein, The calculation of the integral value of the SCR upstream NOx measurement value and the specific emission value of the SCR downstream NOx in the same time period comprises the following steps: obtaining the SCR upstream NOx measurement value and the SCR downstream NOx measurement value collected in the same time period; calculating the integral value of the SCR upstream NOx measurement value based on each SCR upstream NOx measurement value; calculating the specific emission value of the SCR downstream NOx based on each SCR downstream NOx measurement value.

5. The method of claim 1, wherein, After determining that the urea concentration is abnormal, the method further comprises the following step:

6. The method of claim 1, wherein, outputting prompt information of the urea concentration abnormality. The method further comprises the following step:

7. An apparatus for performing the method of any one of claims 1 to 6, characterized by unfreezing the value of the urea injection amount correction factor if the duration for which the urea concentration is lower than the first concentration threshold value is less than the time threshold value. The method comprises the following steps: a freezing module configured to determine a value of a urea injection amount correction factor based on the urea concentration and freeze the value when the urea concentration is detected to be lower than a first concentration threshold value; a specific emission determination module configured to determine a specific emission value of the engine after detecting that the urea concentration is lower than the first concentration threshold value for a duration greater than or equal to a time threshold value, the time threshold value being a time required to eliminate an ammonia storage impact factor; a urea concentration abnormality determination module configured to determine that the urea concentration is abnormal when the specific emission value is greater than or equal to a specific emission limit value. a normal urea concentration determination module configured to determine that the urea concentration is normal when the specific emission value is less than the specific emission limit value.

8. An electronic device, comprising: The electronic device comprises a memory and a controller, the memory stores program instructions, and the controller executes the program instructions to realize the urea concentration abnormality detection method in any one of claims 1-6.

Images