A method and device for analyzing nitrogen oxide emission deviation of a diesel engine

Abstract

The present invention discloses a method and device for analyzing nitrogen oxide emissions deviations from a diesel engine, relating to the field of engine emission technology. The method comprises: when the engine water temperature of a target vehicle is greater than an engine water temperature threshold and the engine oil temperature is greater than an engine oil temperature threshold, monitoring and obtaining engine speed deviation and vehicle speed deviation, and determining whether the target vehicle is in a steady-state operating condition; when the target vehicle is in a steady-state operating condition, obtaining reconstructed engine bench NOx emission data; based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data, obtaining NOx emission average value deviation and instantaneous NOx emission deviation; and determining whether the target vehicle's NOx emissions are normal based on the NOx emission average value deviation and instantaneous NOx emission deviation corresponding to the target vehicle. This application implements non-intrusive NOx monitoring and NOx emission deviation analysis, which is simple, efficient, accurate, and reliable, meeting the needs of actual vehicle emission testing.

Description

Technical Field

[0001] The present invention relates to the technical field of engine emissions, and in particular to a method and device for analyzing nitrogen oxide emission deviations of a diesel engine. Background Art

[0002] In the field of engine emission control system technology, on-vehicle NOx emissions monitoring ensures that vehicle NOx emissions during actual use comply with national emission standards and is a key measure for protecting environmental quality and public health. Through on-vehicle NOx emissions monitoring, the technical performance of vehicle engines and exhaust aftertreatment systems can be evaluated, their emission performance under different operating conditions can be understood, and data support can be provided for vehicle R&D, production, and maintenance. Monitoring results can be used to guide engine design, improve exhaust aftertreatment systems, and develop more efficient emission control technologies to reduce NOx emissions.

[0003] Therefore, in order to meet actual needs, a diesel engine nitrogen oxide emission deviation analysis technology is provided. Summary of the Invention

[0004] In response to the defects existing in the prior art, the purpose of the present invention is to provide a method and device for analyzing nitrogen oxide emissions deviations of diesel engines, which analyzes the operating conditions of the target vehicle, reconstructs the monitoring data, conducts NOx non-intrusive monitoring simply and efficiently, and accurately and reliably analyzes NOx emission deviations to meet the actual vehicle emission testing needs.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present application provides a method for analyzing nitrogen oxide emissions deviations from a diesel engine, the method comprising the following steps:

[0007] When the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold, and the engine oil temperature is greater than a preset engine oil temperature threshold, the engine speed deviation and the vehicle speed deviation are monitored and obtained;

[0008] Based on the engine speed deviation and the vehicle speed deviation, determining whether the target vehicle is in a preset steady-state operating condition;

[0009] When the target vehicle is in the steady-state operating condition, reconstructing the original NOx emission data of the engine bench of the target vehicle to obtain reconstructed NOx emission data of the engine bench;

[0010] Obtaining a NOx emission average value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data;

[0011] Based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle, it is determined whether the NOx emission of the target vehicle is normal.

[0012] Based on the above technical solution, monitoring and obtaining the engine speed deviation and vehicle speed deviation includes the following steps:

[0013] Obtaining an average engine speed and an average vehicle speed within a time period that is equal to a preset first monitoring period and a time difference from the current moment;

[0014] The engine speed deviation and the vehicle speed deviation are obtained based on the real-time engine speed and the real-time vehicle speed of the target vehicle in combination with the average engine speed and the average vehicle speed.

[0015] On the basis of the above technical solution, judging whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation includes the following steps:

[0016] When the engine speed deviation is less than a preset engine speed deviation threshold, and the vehicle speed deviation is less than a preset vehicle speed deviation threshold, it is determined that the target vehicle is in the steady-state operating condition.

[0017] On the basis of the above technical solution, the speed data interval in the speed range of the reconstructed engine test bench NOx emission data is smaller than the speed data interval in the speed range of the original engine test bench NOx emission data;

[0018] The torque data intervals of the torque range of the reconstructed engine test bench NOx emission data are fixed;

[0019] The torque data of the torque range of the engine bench raw NOx emission data are not arranged in order.

[0020] On the basis of the above technical solution, the method further comprises the following steps:

[0021] Obtaining the speed, torque and measured NOx emission values ​​at each operating point in the original NOx emission data of the engine test bench;

[0022] Constructing the theoretical NOx emission value of each operating point in the reconstructed engine bench NOx emission data.

[0023] On the basis of the above technical solution, the method further comprises the following steps:

[0024] Based on the measured NOx emission values ​​at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission values ​​at each operating point in the reconstructed NOx emission data of the engine bench, the corresponding NOx emission average value and the NOx emission theoretical average value are obtained.

[0025] On the basis of the above technical solution, the method further comprises the following steps:

[0026] The NOx emission average value deviation is obtained based on the NOx emission average value and the NOx emission theoretical average value.

[0027] On the basis of the above technical solution, the method further comprises the following steps:

[0028] Based on the measured NOx emission value at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission value at each operating point in the reconstructed NOx emission data of the engine bench, each instantaneous NOx emission deviation is obtained.

[0029] On the basis of the above technical solution, judging whether the NOx emissions of the target vehicle are normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle includes the following steps:

[0030] When the NOx emission average value deviation corresponding to the target vehicle is less than the preset NOx emission average value deviation threshold, and the proportion of the time when the instantaneous NOx emission deviation corresponding to the target vehicle is less than the instantaneous NOx emission deviation threshold is greater than a first proportion threshold, it is determined that the NOx emission of the target vehicle is normal.

[0031] In a second aspect, the present application further provides a diesel engine nitrogen oxide emission deviation analysis device, the device comprising:

[0032] A vehicle monitoring module, which is used to monitor and obtain engine speed deviation and vehicle speed deviation when the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold and the engine oil temperature is greater than a preset engine oil temperature threshold;

[0033] a steady-state determination module, configured to determine whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation;

[0034] a data reconstruction module, configured to reconstruct the original NOx emission data of the engine test bench of the target vehicle when the target vehicle is in the steady-state operating condition, to obtain reconstructed NOx emission data of the engine test bench;

[0035] a data analysis module, configured to obtain a NOx emission mean value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data;

[0036] The emission determination module is used to determine whether the NOx emission of the target vehicle is normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle.

[0037] Based on the above technical solution, the vehicle monitoring module is further configured to obtain an average value of the engine speed and an average value of the vehicle speed within a time period whose time difference from the current moment meets a preset first monitoring period;

[0038] The vehicle monitoring module is further configured to obtain the engine speed deviation and the vehicle speed deviation based on the real-time engine speed and the real-time vehicle speed of the target vehicle in combination with the average engine speed and the average vehicle speed.

[0039] Based on the above technical solution, the steady-state judgment module is also used to determine that the target vehicle is in the steady-state operating condition when the engine speed deviation is less than a preset engine speed deviation threshold and the vehicle speed deviation is less than a preset vehicle speed deviation threshold.

[0040] On the basis of the above technical solution, the speed data interval in the speed range of the reconstructed engine test bench NOx emission data is smaller than the speed data interval in the speed range of the original engine test bench NOx emission data;

[0041] The torque data intervals of the torque range of the reconstructed engine test bench NOx emission data are fixed;

[0042] The torque data of the torque range of the engine bench raw NOx emission data are not arranged in order.

[0043] On the basis of the above technical solution, the data analysis module is further used to obtain the speed, torque and measured NOx emission value of each operating point in the original NOx emission data of the engine test bench;

[0044] The data analysis module is further used to construct theoretical NOx emission values ​​for each operating point in the reconstructed engine bench NOx emission data.

[0045] Based on the above technical solution, the data analysis module is also used to obtain the corresponding NOx emission average value and NOx emission theoretical average value based on the NOx measured emission value at each operating point in the original NOx emission data of the engine test bench and the NOx theoretical emission value at each operating point in the reconstructed NOx emission data of the engine test bench.

[0046] On the basis of the above technical solution, the data analysis module is further used to obtain the NOx emission average value deviation based on the NOx emission average value and the NOx emission theoretical average value.

[0047] Based on the above technical solution, the data analysis module is also used to obtain the instantaneous NOx emission deviations based on the measured NOx emission values ​​at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission values ​​at each operating point in the reconstructed NOx emission data of the engine bench.

[0048] Based on the above technical solution, the emission judgment module is also used to determine that the NOx emissions of the target vehicle are normal when the NOx emission average value deviation corresponding to the target vehicle is less than the preset NOx emission average value deviation threshold, and the proportion of the time when the instantaneous NOx emission deviation corresponding to the target vehicle is less than the instantaneous NOx emission deviation threshold is greater than a first proportion threshold.

[0049] Compared with the prior art, the advantages of the present invention are:

[0050] The present invention analyzes the working conditions of the target vehicle, reconstructs the monitoring data, performs NOx non-intrusive monitoring simply and efficiently, and performs NOx emission deviation analysis accurately and reliably to meet the needs of actual vehicle emission testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0052] Figure 1 A flowchart of a method for analyzing nitrogen oxide emissions deviation from a diesel engine according to an embodiment of the present invention;

[0053] Figure 2 Schematic diagram of raw NOx emission data of an engine test bench in a method for analyzing nitrogen oxide emission deviation of a diesel engine according to an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of steady-state NOx emission reconstruction data in a diesel engine nitrogen oxide emission deviation analysis method according to an embodiment of the present invention;

[0055] Figure 4 Schematic diagram of calculation of operating points beyond the original data range in the diesel engine nitrogen oxide emission deviation analysis method according to an embodiment of the present invention;

[0056] Figure 5 Schematic diagram of calculation of operating points beyond the original data range in the diesel engine nitrogen oxide emission deviation analysis method according to an embodiment of the present invention;

[0057] Figure 6 A graph showing the percentage of vehicles in each segment of the NOx emission average value deviation in the diesel engine nitrogen oxide emission deviation analysis method according to an embodiment of the present invention;

[0058] Figure 7 A graph showing the proportion of vehicles in each segment when the instantaneous NOx emission deviation is less than 10% in the diesel engine nitrogen oxide emission deviation analysis method according to an embodiment of the present invention;

[0059] Figure 8 This is a structural block diagram of a device for analyzing nitrogen oxide emissions deviation from a diesel engine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0061] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0062] The embodiments of the present application provide a method and device for analyzing nitrogen oxide emission deviations of a diesel engine, which performs analysis based on the operating conditions of a target vehicle, reconstructs monitoring data, performs non-intrusive NOx monitoring simply and efficiently, and accurately and reliably performs NOx emission deviation analysis to meet the needs of actual vehicle emission testing.

[0063] To achieve the above technical effects, the overall idea of ​​this application is as follows:

[0064] A method for analyzing nitrogen oxide emission deviations of a diesel engine, the method comprising the following steps:

[0065] S1. When the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold and the engine oil temperature is greater than a preset engine oil temperature threshold, monitoring and obtaining an engine speed deviation and a vehicle speed deviation;

[0066] S2. Determining whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation;

[0067] S3. When the target vehicle is in a steady-state operating condition, reconstructing the original NOx emission data of the engine bench of the target vehicle to obtain reconstructed NOx emission data of the engine bench;

[0068] S4. Obtaining a NOx emission average value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data;

[0069] S5. Determine whether the NOx emissions of the target vehicle are normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle.

[0070] The embodiments of the present application are further described in detail below with reference to the accompanying drawings.

[0071] First, see Figures 1 to 7 As shown, the embodiment of the present application provides a method for analyzing nitrogen oxide emission deviation of a diesel engine, the method comprising the following steps:

[0072] S1. When the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold and the engine oil temperature is greater than a preset engine oil temperature threshold, monitoring and obtaining an engine speed deviation and a vehicle speed deviation;

[0073] S2. Determining whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation;

[0074] S3. When the target vehicle is in a steady-state operating condition, reconstructing the original NOx emission data of the engine bench of the target vehicle to obtain reconstructed NOx emission data of the engine bench;

[0075] S4. Obtaining a NOx emission average value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data;

[0076] S5. Determine whether the NOx emissions of the target vehicle are normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle.

[0077] It should be noted that the technical solution of the embodiment of the present application is mainly aimed at measuring the nitrogen oxide emissions of vehicles during actual vehicle emission testing, environmental protection supervision, and vehicle development to ensure that vehicle emissions meet consistency requirements and comply with environmental protection standards. It mainly solves the technical difficulties of non-intrusive monitoring of NOx detection and the analysis of NOx emission deviations.

[0078] Currently, the primary method for testing vehicle nitrogen oxide emissions is to use an on-board exhaust gas monitoring system (PEMS) to measure vehicle emissions in real time, including the concentrations of pollutants such as carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter. The PEMS collects pollutant concentrations through a probe connected to the vehicle's exhaust pipe and obtains relevant engine and vehicle technical parameters through the vehicle's OBD (On-Board Diagnostics) interface to calculate the vehicle's exhaust emissions.

[0079] However, using a PEMS system for vehicle exhaust emissions testing is subject to a range of environmental factors, including temperature, road conditions, and altitude, which can affect the accuracy of measurement results. Furthermore, PEMS must be installed in the vehicle, which can present challenges such as selecting the correct installation location and connecting the sensor to the exhaust pipe.

[0080] By using the technical solution of the embodiment of the present application, a steady-state judgment can be made on the current vehicle and engine status based on the emission data of the front NOx sensor sent by the current engine Tbox to the cloud platform, as well as the engine speed and vehicle speed signals;

[0081] Compare and analyze the NOx data at steady-state operating points with the engine bench steady-state data stored in the database to determine whether the engine NOx emissions are deviating;

[0082] When there is a NOx emission deviation, a risk warning of a large NOx emission deviation can be promptly issued to the after-sales service platform through the cloud platform, reminding the after-sales service personnel to pay attention to the vehicle's excessive emissions, make a secondary judgment based on the background monitoring data, and then push a maintenance notification to the vehicle driver's mobile phone.

[0083] In the embodiment of the present application, the operating conditions of the target vehicle are analyzed, the monitoring data is reconstructed, NOx non-intrusive monitoring is performed simply and efficiently, and NOx emission deviation analysis is performed accurately and reliably to meet the actual vehicle emission detection needs.

[0084] Furthermore, monitoring and obtaining the engine speed deviation and the vehicle speed deviation includes the following steps:

[0085] Obtaining an average engine speed and an average vehicle speed within a time period that is equal to a preset first monitoring period and a time difference from the current moment;

[0086] The engine speed deviation and the vehicle speed deviation are obtained based on the real-time engine speed and the real-time vehicle speed of the target vehicle in combination with the average engine speed and the average vehicle speed.

[0087] Furthermore, judging whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation includes the following steps:

[0088] When the engine speed deviation is less than a preset engine speed deviation threshold, and the vehicle speed deviation is less than a preset vehicle speed deviation threshold, it is determined that the target vehicle is in the steady-state operating condition.

[0089] Furthermore, the speed data interval in the speed range of the reconstructed engine test bench NOx emission data is smaller than the speed data interval in the speed range of the original engine test bench NOx emission data;

[0090] The torque data intervals of the torque range of the reconstructed engine test bench NOx emission data are fixed;

[0091] The torque data of the torque range of the engine bench raw NOx emission data are not arranged in order.

[0092] Furthermore, the method further comprises the following steps:

[0093] Obtaining the speed, torque and measured NOx emission values ​​at each operating point in the original NOx emission data of the engine test bench;

[0094] Constructing the theoretical NOx emission value of each operating point in the reconstructed engine bench NOx emission data.

[0095] Furthermore, the method further comprises the following steps:

[0096] Based on the measured NOx emission values ​​at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission values ​​at each operating point in the reconstructed NOx emission data of the engine bench, the corresponding NOx emission average value and the NOx emission theoretical average value are obtained.

[0097] Furthermore, the method further comprises the following steps:

[0098] The NOx emission average value deviation is obtained based on the NOx emission average value and the NOx emission theoretical average value.

[0099] Furthermore, the method further comprises the following steps:

[0100] Based on the measured NOx emission value at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission value at each operating point in the reconstructed NOx emission data of the engine bench, each instantaneous NOx emission deviation is obtained.

[0101] Furthermore, judging whether the NOx emissions of the target vehicle are normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle includes the following steps:

[0102] When the NOx emission average value deviation corresponding to the target vehicle is less than the preset NOx emission average value deviation threshold, and the proportion of the time when the instantaneous NOx emission deviation corresponding to the target vehicle is less than the instantaneous NOx emission deviation threshold is greater than a first proportion threshold, it is determined that the NOx emission of the target vehicle is normal.

[0103] Based on the technical solution of the embodiment of this application, during specific implementation, the situation is as follows:

[0104] The first step is to determine the engine steady-state operating conditions:

[0105] When the engine water temperature is greater than Tc1°C and the oil temperature is greater than To2°C, the engine speed and vehicle speed are calculated as a sliding average over a continuous period of t1 seconds. The current engine speed and vehicle speed are calculated as follows:

[0106] Formula 1: Engine speed deviation = ABS (current engine speed - average speed during the previous t1 seconds) / average speed during the previous t1 seconds;

[0107] Formula 2: Vehicle speed deviation = ABS (current vehicle speed - average vehicle speed during the last t1 seconds) / average vehicle speed during the last t1 seconds;

[0108] If the engine speed deviation is less than m and the vehicle speed deviation is less than n, it is determined that the engine is in a steady-state operating condition.

[0109] Specifically, the calculation of the theoretical value of NOx emissions at the steady-state operating point is shown in the third step.

[0110] The second step is to reconstruct the steady-state NOx concentration emission data:

[0111] As shown in the accompanying drawings Figure 2 As shown, it is the original NOx emission data of the engine bench, the speed range is [n1, n2] with an interval of n3, and the torque range is [Te1, Te2] with an unordered interval.

[0112] Reconstruct the original emission data according to the algorithm provided in step 4, as shown in the attached figure of the specification. Figure 3 As shown, the speed range remains unchanged, the interval is narrowed to n4, and the torque range is [0, Te3] and the interval is solidified to Te4.

[0113] When the operating point determined for speed and torque exceeds the original data range, the nearest calculation method is used. The calculation method is shown in the figure attached to the specification. Figure 4 shown.

[0114] exist Figure 4 Middle: The reconstructed operating points 1' and 2' exceed the range of the original operating points. The values ​​of the closest original operating points 1 and 2 are assigned to 1' and 2'.

[0115] The values ​​of points 4' and 5' at the same speed are respectively continued to use the values ​​of points 1' and 2' that are beyond the range of the original operating points at the same speed.

[0116] For other reconstructed operating points under the same torque, such as 3' and 6', the algorithm formula 5 provided in the third step is used to calculate them.

[0117] The third step is to calculate the theoretical value of NOx emissions from the actual vehicle:

[0118] Compare the speed and torque values ​​of the current working point with the steady-state NOx emission reconstruction data to find the four known data points surrounding the working point. The specific point-finding algorithm is shown in the attached figure of the specification. Figure 5 shown.

[0119] In the diagram, point (i', j') represents the current operating point. A virtual coordinate system (X', Y') is established through this point, parallel to the X and Y axes, as indicated by the dashed axes. To the left of the Y' axis, a perpendicular line is drawn from the known speed points in the steady-state NOx emissions reconstruction data. The point with the shortest perpendicular distance is the speed point to the left of the current operating point, i.e., the point with X coordinate i in the diagram. Therefore, the point i+1 to the immediate right of i is the speed point to the right of the current operating point.

[0120] Similarly, on the upper side of the X'-axis, draw a perpendicular line from the known speed points in the steady-state NOx emissions reconstruction data to the X'-axis. The point with the shortest perpendicular distance is the upper torque point of the current operating point, i.e., the point with Y coordinate j+1 in the diagram. Then, the point j immediately below j+1 is the lower torque point of the current operating point.

[0121] The above shows that the four points surrounding (i', j') are found, namely (i, j), (i, j+1), (i+1, j'), and (i+1, j+1). The speed, torque, and NOx emissions corresponding to the four points are set as ①(N1, T1, NOx1), ②(N1, T2, NOx2), ③(N2, T1, NOx3), and ④(N2, T2, NOx4). The speed and torque of the known operating point are (N, T), and the intersection point of the line connecting points ① and ② is ⑤, and the intersection point of the line connecting points ③ and ④ is ⑥. The speed and torque of points ⑤ and ⑥ are (N1, T) and (N2, T), respectively, and the calculation method of their NOx emission values ​​is as follows:

[0122] Formula 3: NOx5 = (T-T1)(NOx2-NOx1) / (T2-T1)+NOx1.

[0123] Formula 4: NOx6 = (T-T1)(NOx4-NOx3) / (T2-T1)+NOx3.

[0124] The theoretical NOx emission value at the current operating point can be obtained using formula 5:

[0125] Formula 5: NOx = (N-N1)(NOx6-NOx5) / (N2-N1)+NOx5.

[0126] Based on the technical solution of the embodiment of the present application, a single-vehicle analysis method for NOx emission deviation based on steady-state emission data can be implemented as follows:

[0127] After obtaining the corresponding theoretical NOx emission value at the operating point that meets the steady-state operating conditions, the NOx emission average value deviation and the instantaneous NOx emission deviation are calculated respectively, as shown in Equations 6 and 7.

[0128] Formula 6: Average NOx emission value = AVE (actual NOx value under steady-state conditions).

[0129] Formula 7: NOx theoretical emission average value = AVE (NOx theoretical emission value under steady-state conditions).

[0130] Formula 8: NOx emission average deviation = (NOx emission average – NOx theoretical emission average) / NOx theoretical emission average.

[0131] Formula 9: Instantaneous NOx emission deviation = ABS (steady-state NOx measured value - steady-state NOx theoretical emission value) / steady-state NOx theoretical emission value.

[0132] Formula 10: Percentage of time when the instantaneous NOx emission deviation is less than 10% = sum (number of operating condition points when the instantaneous NOx emission deviation is less than 10%) / vehicle operating time.

[0133] When the average NOx emission deviation of a single vehicle in steady-state conditions is less than m1(%) and the proportion of time when the instantaneous NOx emission deviation is less than 10% is greater than n1(%), it can be judged that the NOx emission of the single vehicle is normal.

[0134] Based on the technical solution of the embodiment of the present application, a multi-vehicle analysis method for NOx emission deviation based on steady-state emission data can be implemented as follows:

[0135] The NOx emission average deviation of each vehicle can be obtained by formula 8. The NOx emission average deviation of each vehicle is segmented, with 10 (unit: %) as the interval size, and the left-closed and right-open design principle is adopted, from -100 to 100, it is divided into 20 intervals [-100, -90)

[0136] [-90, -80), ..., [80, 90), [90, 100]. The statistically analyzed average NOx emission deviations for each vehicle are placed into each of the above segments, and the ratio of the number of vehicles in each segment to the total number of vehicles is calculated.

[0137] Equation 10 provides the percentage of time when the instantaneous NOx emissions deviation is less than 10% for each steady-state operating point. This percentage is then segmented, with 10 (unit: %) intervals used. Using the left-closed, right-open design principle, the range from 0-100 is divided into 10 intervals: [0, 10), [10, 20), [20, 30), [30, 40), [40, 50), [50, 60), [60, 70), [70, 80), [80, 90), [90, 100]. The percentage of time when the instantaneous NOx emissions deviation is less than 10% for each vehicle analyzed is then placed into each of the aforementioned segments, and the ratio of the number of vehicles in each segment to the total number of vehicles is calculated.

[0138] If the cumulative value of the deviation distribution of the average NOx emissions of multiple vehicles is less than [10, 20) and is greater than m2(%), and the proportion of the time when the instantaneous NOx emission deviation is less than 10% is greater than [80, 90) and is greater than n2(%), it can be judged that the NOx emissions of this batch of vehicles are normal.

[0139] Based on the technical solution of the embodiment of the present application, the NOx sensor on the engine exhaust after-treatment system is used to complete the identification of NOx emission deviation.

[0140] While PEMS can accurately sample single-vehicle emissions data in real time, its data volume is relatively limited and cannot cover all possible operating conditions and vehicles. Big data-based NOx emissions deviation detection, however, involves massive amounts of data samples, resulting in more comprehensive analysis results that reflect the overall emissions situation and trends across multiple vehicles.

[0141] By utilizing background data and deviation calculation methods, emission deviations can be detected in a timely manner and corresponding measures can be taken to intervene and adjust problem vehicles.

[0142] As shown in the accompanying drawings Figure 6 and 7 As shown in the figure, using the multi-vehicle analysis of NOx emissions deviation as an example, after calculating the theoretical NOx emissions value and the individual vehicle emissions deviation using this method, the percentage of vehicles in each segment with the average NOx emissions deviation and the percentage of vehicles in each segment with transient NOx emissions deviation less than 10% are plotted. These two percentage distributions can be used to determine whether the overall NOx emissions deviation for a group of vehicles is normal based on the set percentage standard.

[0143] Second, see Figure 6As shown, an embodiment of the present application provides a diesel engine nitrogen oxide emission deviation analysis device, which includes:

[0144] A vehicle monitoring module, which is used to monitor and obtain engine speed deviation and vehicle speed deviation when the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold and the engine oil temperature is greater than a preset engine oil temperature threshold;

[0145] a steady-state determination module, configured to determine whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation;

[0146] a data reconstruction module, configured to reconstruct the original NOx emission data of the engine test bench of the target vehicle when the target vehicle is in the steady-state operating condition, to obtain reconstructed NOx emission data of the engine test bench;

[0147] a data analysis module, configured to obtain a NOx emission mean value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data;

[0148] The emission determination module is used to determine whether the NOx emission of the target vehicle is normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle.

[0149] In the embodiment of the present application, the operating conditions of the target vehicle are analyzed, the monitoring data is reconstructed, NOx non-intrusive monitoring is performed simply and efficiently, and NOx emission deviation analysis is performed accurately and reliably to meet the actual vehicle emission detection needs.

[0150] Furthermore, the vehicle monitoring module is further configured to obtain an average value of the engine speed and an average value of the vehicle speed within a time period whose time difference from the current moment meets a preset first monitoring period;

[0151] The vehicle monitoring module is further configured to obtain the engine speed deviation and the vehicle speed deviation based on the real-time engine speed and the real-time vehicle speed of the target vehicle in combination with the average engine speed and the average vehicle speed.

[0152] Furthermore, the steady-state determination module is also used to determine that the target vehicle is in the steady-state operating condition when the engine speed deviation is less than a preset engine speed deviation threshold and the vehicle speed deviation is less than a preset vehicle speed deviation threshold.

[0153] Furthermore, the speed data interval in the speed range of the reconstructed engine test bench NOx emission data is smaller than the speed data interval in the speed range of the original engine test bench NOx emission data;

[0154] The torque data intervals of the torque range of the reconstructed engine test bench NOx emission data are fixed;

[0155] The torque data of the torque range of the engine bench raw NOx emission data are not arranged in order.

[0156] Furthermore, the data analysis module is further used to obtain the speed, torque and measured NOx emission value of each operating point in the original NOx emission data of the engine test bench;

[0157] The data analysis module is further used to construct theoretical NOx emission values ​​for each operating point in the reconstructed engine bench NOx emission data.

[0158] Furthermore, the data analysis module is also used to obtain the corresponding NOx emission average value and NOx emission theoretical average value based on the NOx measured emission value at each operating point in the original NOx emission data of the engine test bench and the NOx theoretical emission value at each operating point in the reconstructed NOx emission data of the engine test bench.

[0159] Furthermore, the data analysis module is further configured to obtain the NOx emission average value deviation based on the NOx emission average value and the NOx emission theoretical average value.

[0160] Furthermore, the data analysis module is also used to obtain each instantaneous NOx emission deviation based on the NOx measured emission value at each operating point in the original NOx emission data of the engine bench and the NOx theoretical emission value at each operating point in the reconstructed NOx emission data of the engine bench.

[0161] Furthermore, the emission judgment module is also used to determine that the NOx emissions of the target vehicle are normal when the NOx emission average value deviation corresponding to the target vehicle is less than a preset NOx emission average value deviation threshold, and the proportion of time when the instantaneous NOx emission deviation corresponding to the target vehicle is less than the instantaneous NOx emission deviation threshold is greater than a first proportion threshold.

[0162] It should be noted that the diesel engine nitrogen oxide emission deviation analysis device mentioned in the second aspect is similar to the technical principles of the diesel engine nitrogen oxide emission deviation analysis method mentioned in the first aspect in terms of technical issues, technical means and technical effects, and will not be elaborated here.

[0163] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0164] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0165] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for analyzing deviation of nitrogen oxide emissions from a diesel engine, characterized in that: The method comprises the following steps: When the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold, and the engine oil temperature is greater than a preset engine oil temperature threshold, the engine speed deviation and the vehicle speed deviation are monitored and obtained; Based on the engine speed deviation and the vehicle speed deviation, determining whether the target vehicle is in a preset steady-state operating condition; When the target vehicle is in the steady-state operating condition, reconstructing the original NOx emission data of the engine bench of the target vehicle to obtain reconstructed NOx emission data of the engine bench; Obtaining a NOx emission average value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data; Based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle, it is determined whether the NOx emission of the target vehicle is normal.

2. The diesel engine nitrogen oxide emission deviation analysis method according to claim 1, characterized in that: Monitoring and obtaining engine speed deviation and vehicle speed deviation includes the following steps: Obtaining an average engine speed and an average vehicle speed within a time period that is equal to a preset first monitoring period and a time difference from the current moment; The engine speed deviation and the vehicle speed deviation are obtained based on the real-time engine speed and the real-time vehicle speed of the target vehicle in combination with the average engine speed and the average vehicle speed.

3. The diesel engine nitrogen oxide emission deviation analysis method according to claim 2, characterized in that: Determining whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation includes the following steps: When the engine speed deviation is less than a preset engine speed deviation threshold, and the vehicle speed deviation is less than a preset vehicle speed deviation threshold, it is determined that the target vehicle is in the steady-state operating condition.

4. The diesel engine nitrogen oxide emission deviation analysis method according to claim 1, characterized in that: The speed data interval in the speed range of the reconstructed engine test bench NOx emission data is smaller than the speed data interval in the speed range of the original engine test bench NOx emission data; The torque data intervals of the torque range of the reconstructed engine test bench NOx emission data are fixed; The torque data of the torque range of the engine bench raw NOx emission data are not arranged in order.

5. The diesel engine nitrogen oxide emission deviation analysis method according to claim 1, characterized in that: The method further comprises the following steps: Obtaining the speed, torque and measured NOx emission values ​​at each operating point in the original NOx emission data of the engine test bench; Constructing the theoretical NOx emission value of each operating point in the reconstructed engine bench NOx emission data.

6. The diesel engine nitrogen oxide emission deviation analysis method according to claim 5, characterized in that: The method further comprises the following steps: Based on the measured NOx emission values ​​at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission values ​​at each operating point in the reconstructed NOx emission data of the engine bench, the corresponding NOx emission average value and the NOx emission theoretical average value are obtained.

7. The diesel engine nitrogen oxide emission deviation analysis method according to claim 6, characterized in that: The method further comprises the following steps: The NOx emission average value deviation is obtained based on the NOx emission average value and the NOx emission theoretical average value.

8. The diesel engine nitrogen oxide emission deviation analysis method according to claim 7, characterized in that: The method further comprises the following steps: Based on the measured NOx emission value at each operating point in the original NOx emission data of the engine bench and the theoretical NOx emission value at each operating point in the reconstructed NOx emission data of the engine bench, each instantaneous NOx emission deviation is obtained.

9. The diesel engine nitrogen oxide emission deviation analysis method according to claim 8, characterized in that: Determining whether the NOx emissions of the target vehicle are normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle includes the following steps: When the NOx emission average value deviation corresponding to the target vehicle is less than the preset NOx emission average value deviation threshold, and the proportion of the time when the instantaneous NOx emission deviation corresponding to the target vehicle is less than the instantaneous NOx emission deviation threshold is greater than a first proportion threshold, it is determined that the NOx emission of the target vehicle is normal.

10. A diesel engine nitrogen oxide emission deviation analysis device, characterized in that: The device comprises: A vehicle monitoring module, which is used to monitor and obtain engine speed deviation and vehicle speed deviation when the engine water temperature of the target vehicle is greater than a preset engine water temperature threshold and the engine oil temperature is greater than a preset engine oil temperature threshold; a steady-state determination module, configured to determine whether the target vehicle is in a preset steady-state operating condition based on the engine speed deviation and the vehicle speed deviation; a data reconstruction module, configured to reconstruct the original NOx emission data of the engine test bench of the target vehicle when the target vehicle is in the steady-state operating condition, to obtain reconstructed NOx emission data of the engine test bench; a data analysis module, configured to obtain a NOx emission mean value deviation and an instantaneous NOx emission deviation based on the reconstructed engine bench NOx emission data and the original engine bench NOx emission data; The emission determination module is used to determine whether the NOx emission of the target vehicle is normal based on the NOx emission average value deviation and the instantaneous NOx emission deviation corresponding to the target vehicle.

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