Method for detecting cheating behavior in exhaust gas testing for temporarily installed three-way catalytic converters

Abstract

The present invention belongs to the field of vehicle detection technology, and provides a method for detecting cheating behavior of exhaust gas detection for temporarily installing a three-way catalytic converter. The detection method includes the following steps: screening motor vehicle detection history data according to the vehicle model, determining the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold of each vehicle model; obtaining motor vehicle detection process data, determining the vehicle model, and comparing the motor vehicle detection process data with the four thresholds of the vehicle model. If at least three are present, it is determined that there is a suspicion of cheating behavior of installing a temporary three-way catalytic converter. The present invention combines the pollutant concentration data, engine operating condition data, oil temperature data and exhaust gas flow data in the exhaust gas emissions of the motor vehicle to comprehensively identify the temporarily installed three-way catalytic converter, and the operation is simple, efficient and has strong recognition ability.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle detection, and in particular relates to a method for detecting cheating behavior in exhaust gas detection of a temporarily installed three-way catalytic converter. Background Art

[0002] With the rapid growth of the number of motor vehicles, my country's air pollution is showing a trend of changing from coal smoke to a mixture of coal smoke and motor vehicle exhaust. The proportion of pollution caused by motor vehicle exhaust emissions in air pollution is increasing year by year. The main pollutants in motor vehicle exhaust include CO, NO, N0 2 The emission of each pollutant increases year by year. If vehicles fail to meet emission standards for a long time, it will not only aggravate air pollution and deteriorate the atmospheric environment, but also affect human health and threaten human survival, and damage vehicles and increase fuel consumption. Therefore, motor vehicle exhaust detection is very important.

[0003] In the process of motor vehicle exhaust testing, in order to temporarily reduce the concentration of pollutants in motor vehicle exhaust, a variety of cheating methods have emerged. Some lawbreakers temporarily insert a short-term strong three-way catalytic converter into the exhaust pipe of a motor vehicle, such as a "steel wool" coated with a small amount of three-way catalyst. The components of the three-way catalyst are relatively expensive, and the effective components coated by the "steel wool" are relatively low. That is, the main purpose is to temporarily pass the motor vehicle environmental protection test, which is one of the common cheating methods.

[0004] At present, there are some methods and devices for automatically detecting cheating in exhaust gas detection. For example, the Chinese invention patent with application publication number CN108763966A discloses an exhaust gas detection cheating supervision system and method, which can identify invalid detection data; stop the detection process when invalid data appears; directly connect with the detection instrument, read the historical records, and directly compare with the records uploaded to the server to determine whether the data has been tampered with; identify abnormal data through data analysis and manual intervention; classify and learn the core indicators in the detection data, find frequently repeated data patterns, and perform manual screening; through the association algorithm, use the correlation between the analysis process data and the result data, the vehicle attributes and the detection result data to issue an early warning for non-compliant rules. This patent only uses data such as detection results, and it is difficult to effectively identify the temporarily installed short-term strong three-way catalytic converter, and the missed detection rate and false detection rate are high.

[0005] Therefore, the main existing method of identifying this type of "steel wool" is to use the human eye to identify and use a probe to detect whether there is a "steel wool" in the exhaust pipe. This method has many problems: 1. The position and airway shape of the exhaust pipe of a motor vehicle are not uniform, and the efficiency of manual inspection is low. 2. The exhaust pipe of a motor vehicle emits polluted gases, and it is not good for the health of inspectors to be close to the inspection for a long time. 3. The exhaust pipe is a high-temperature component during the operation of the motor vehicle, and there is a safety risk of burns for inspectors to observe closely. 4. It has been discovered that some people have upgraded the "steel wool" and implanted it inside the three-way catalytic converter of the motor vehicle, which is more concealed and difficult to detect by manpower. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the present invention provides a method for detecting cheating behavior in exhaust gas detection of temporarily installed three-way catalytic converters. The method combines pollutant concentration data, engine operating condition data, oil temperature data and exhaust gas flow rate data in motor vehicle exhaust emissions to comprehensively identify temporarily installed three-way catalytic converters. The method has extremely high accuracy and is simple to operate, efficient and has strong recognition capability compared to traditional anti-cheating methods such as manual visual recognition and probe rod recognition.

[0007] The technical solution adopted by the present invention is: a method for detecting cheating behavior of exhaust gas detection for temporarily installed three-way catalytic converters, comprising the following steps:

[0008] Step 1: Collect historical data on motor vehicle inspections;

[0009] Step 2: Filter the historical data according to vehicle models, and then determine the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold for each vehicle model;

[0010] Step 3: Obtain the vehicle detection process data, determine the vehicle model, and compare the vehicle detection process data with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold corresponding to the vehicle model. If at least three of the detection standards are met, it is determined that there is a suspicion of cheating by installing a temporary three-way catalytic converter.

[0011] The testing standards are:

[0012] a. the pollutant emission concentration change rate of the motor vehicle detection process data is higher than the pollutant emission concentration change rate threshold,

[0013] b. the average value of the engine oil temperature of the motor vehicle detection process data is higher than the engine oil temperature threshold,

[0014] c. the average exhaust gas flow rate of the motor vehicle detection process data is lower than the exhaust gas flow rate threshold,

[0015] d. The engine speed of the motor vehicle detection process data falls within the engine operating condition threshold.

[0016] Furthermore, it also includes step 4: conducting manual direct inspection on the motor vehicle suspected of cheating by installing a temporary three-way catalytic converter to determine whether cheating has occurred.

[0017] Furthermore, in step 1, the motor vehicle detection historical data is preprocessed, including processing missing data, outliers and duplicate data, and formatting and unifying timestamps.

[0018] Furthermore, the vehicle model is determined by motor vehicle characteristics, and the motor vehicle characteristics include at least one of vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type.

[0019] Furthermore, the method for determining the pollutant emission concentration change rate threshold is:

[0020] The sampling sequence (x 1 ,y 1 ),(x 2 ,y 2 ),…,(x i ,y i ), record y i is the pollutant concentration at the i-th time point, x i For the corresponding time point, a linear regression model is constructed for each pollutant emission concentration in the filtered historical data:

[0021] y i =β 0 +β 1 x i +∈ i

[0022] Where: β 0 is the intercept term, ∈ i is the error term, β 1 is the slope,

[0023] The pollutant emission concentration change rate threshold θ takes all β 1 The average value of .

[0024] The method for determining the engine oil temperature threshold is:

[0025] Let the set S 1i For all the filtered oil temperature values ​​in the historical data, calculate the overall average value:

[0026]

[0027] Then calculate the overall standard deviation:

[0028]

[0029] The engine oil temperature threshold is:

[0030] T 1 =μ 1 +2δ 1 .

[0031] The method for determining the exhaust gas flow rate threshold is as follows:

[0032] Let the set S 2i For all the filtered exhaust gas flow values ​​of the historical data, calculate the overall average value:

[0033]

[0034] Then calculate the overall standard deviation:

[0035]

[0036] The exhaust gas flow rate threshold is:

[0037] T 2 =μ 2 +2δ 2 .

[0038] The method for determining the engine operating condition threshold is:

[0039] If the engine is turned off, its speed is 0, and the engine operating condition threshold value Z is 0.

[0040] The technical solution adopted by the present invention is: a detection system for cheating behavior of exhaust gas detection of a temporarily installed three-way catalytic converter, comprising:

[0041] A threshold calculation unit, used to screen the historical data of motor vehicle detection according to the vehicle model, and then determine the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold for each vehicle model;

[0042] A data acquisition unit, used to obtain motor vehicle inspection process data;

[0043] The detection unit is used to determine the vehicle model corresponding to the motor vehicle detection process data, and compare the motor vehicle detection process data with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold of the vehicle model. If at least three of the detection standards are met, it is determined that there is a suspicion of cheating by installing a temporary three-way catalytic converter.

[0044] The testing standards are:

[0045] a. the pollutant emission concentration change rate of the motor vehicle detection process data is higher than the pollutant emission concentration change rate threshold,

[0046] b. the average value of the engine oil temperature of the motor vehicle detection process data is higher than the engine oil temperature threshold,

[0047] c. the average exhaust gas flow rate of the motor vehicle detection process data is lower than the exhaust gas flow rate threshold,

[0048] d. the engine speed of the motor vehicle detection process data falls within the engine operating condition threshold;

[0049] The detection unit is connected to the threshold calculation unit and the data acquisition unit respectively.

[0050] Further, the threshold calculation unit includes a historical data preprocessing unit, a historical data screening unit, a pollutant emission concentration change rate threshold calculation unit, an engine oil temperature threshold calculation unit, an exhaust gas flow rate threshold calculation unit and an engine operating condition threshold calculation unit, the historical data preprocessing unit is connected to the historical data screening unit, and the historical data screening unit is respectively connected to the pollutant emission concentration change rate threshold calculation unit, the engine oil temperature threshold calculation unit, the exhaust gas flow rate threshold calculation unit and the engine operating condition threshold calculation unit,

[0051] The historical data preprocessing unit preprocesses the motor vehicle detection historical data, and the preprocessing includes processing missing data, abnormal values ​​and duplicate data, and formatting and unifying timestamps;

[0052] The historical data screening unit screens the preprocessed motor vehicle detection historical data according to the vehicle model, the vehicle model is determined by the vehicle characteristics, and the vehicle characteristics include at least one of the vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type;

[0053] The calculation process of the pollutant emission concentration change rate threshold value calculation unit is as follows:

[0054] The sampling sequence (x 1 ,y 1 ),(x 2 ,y 2 ),…,(x i ,y i ), record y i is the pollutant concentration at the i-th time point, x iFor the corresponding time point, a linear regression model is constructed for each pollutant emission concentration in the filtered historical data:

[0055] y i =β 0 +β 1 x i +∈ i

[0056] Where: β 0 is the intercept term, ∈ i is the error term, β 1 is the slope,

[0057] Calculate all β 1 The average value of is taken as the pollutant emission concentration change rate threshold θ;

[0058] The calculation process of the engine oil temperature threshold calculation unit is as follows:

[0059] Let the set S 1i For all the filtered oil temperature values ​​in the historical data, calculate the overall average value:

[0060]

[0061] Then calculate the overall standard deviation:

[0062]

[0063] The engine oil temperature threshold is:

[0064] T 1 =μ 1 +2δ 1 ;

[0065] The calculation process of the exhaust gas flow rate threshold value calculation unit is as follows:

[0066] Let the set S 2i For all the filtered exhaust gas flow values ​​of the historical data, calculate the overall average value:

[0067]

[0068] Then calculate the overall standard deviation:

[0069]

[0070] The exhaust gas flow rate threshold is:

[0071] T 2 =μ 2 +2δ 2 ;

[0072] The calculation process of the engine operating condition threshold value calculation unit is as follows:

[0073] If the engine is turned off, its speed is 0, and the engine operating condition threshold value Z is 0.

[0074] Furthermore, it also includes a motor vehicle feature selection unit, which is used to determine the motor vehicle features with the least number corresponding to each vehicle model, and the motor vehicle feature selection unit is connected to the threshold calculation unit.

[0075] Furthermore, the motor vehicle feature selection unit adopts a fully connected neural network model, whose input is the preprocessed motor vehicle detection history data that does not meet the four detection standards, and whose output is the motor vehicle feature.

[0076] The technical solution adopted by the present invention is: a computer-readable storage medium, including a program, which can be executed by a processor to implement the above-mentioned exhaust gas detection cheating behavior detection method for temporarily installed three-way catalytic converters.

[0077] Working principle: According to the influence of installing a temporary three-way catalytic converter on the motor vehicle, the present invention selects the pollutant emission concentration change rate, engine oil temperature, exhaust gas flow rate and engine operating conditions as detection standards.

[0078] (1) Exhaust pollutant concentration data

[0079] The three-way catalytic converter, an exhaust gas treatment device equipped in motor vehicles, is a device used to reduce the emission of harmful substances in automobile exhaust. It can effectively convert the three main pollutants in exhaust gas: carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx). When the exhaust gas passes through the catalyst, the precious metals inside the catalyst, such as platinum, palladium, rhodium, etc., will cause these harmful gases to undergo chemical reactions at a lower temperature, thereby converting them into relatively harmless substances, such as carbon dioxide (CO 2 ), water (H 2 O) and nitrogen (N 2 ).

[0080] However, the precious metals inside the three-way catalytic converter are very expensive. Rhodium was once known as the most expensive metal in the world. Therefore, there are very few effective ingredients for converting pollutants in the temporary three-way catalytic converter, which is reflected in the test data as large fluctuations in exhaust emissions or deterioration in a relatively short period of time.

[0081] (2) Engine oil temperature data

[0082] The temporary three-way catalytic converter will block the engine exhaust pipe, causing the engine exhaust to be blocked and the temperature to rise. By judging the trend and severity of temperature changes, the temporary three-way catalytic converter can be identified.

[0083] (3) Exhaust gas flow data

[0084] The engine exhaust is not smooth and the exhaust flow rate of the exhaust gas is reduced.

[0085] (4) Engine operating data

[0086] The presence of foreign objects such as temporary three-way catalytic converters in the exhaust pipe may increase the exhaust resistance of the vehicle, causing the engine to idle at higher speeds or unstable idling. In severe cases, it may cause the engine to stall or become difficult to start.

[0087] Compared with the prior art, the present invention has the following beneficial effects:

[0088] 1. The present invention analyzes the impact of installing a temporary three-way catalytic converter on the motor vehicle detection process data of motor vehicle exhaust detection, determines the pollutant emission concentration change rate, engine oil temperature, exhaust gas flow rate and engine operating conditions as detection standards, and according to the different degrees of their impact on the motor vehicle detection process data, at least three of the detection standards are met as the standard for determining the existence of cheating behavior, and the accuracy of the judgment reaches 100%, without missed detection or wrong detection. It still has the ability to identify temporary three-way catalytic converters that are installed more covertly.

[0089] 2. The present invention uses historical motor vehicle detection data to determine the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold for each vehicle model. The four thresholds are in line with the actual vehicle condition of the motor vehicle, which helps to improve the accuracy of the judgment.

[0090] 3. The present invention uses the data of the motor vehicle detection process of the existing motor vehicle exhaust detection system for analysis and judgment. The data collection and analysis process is automatically processed, and no special operating specifications are required for manual detection of temporary three-way catalytic converters. Therefore, the operation is simple and efficient, and it can also avoid the behavior of on-site operators detecting temporary three-way catalytic converters but not reporting them. The staff does not need to observe the motor vehicle exhaust pipe with the naked eye on site, or use a probe to insert the motor vehicle exhaust pipe, which can avoid personnel from contacting an overheated exhaust pipe or an exhaust pipe that is emitting exhaust gas, which is safer for people.

[0091] 4. The present invention determines the vehicle model by the characteristics of the vehicle, can directly determine the vehicle model based on the vehicle detection process data, and compare and analyze the four thresholds of the vehicle model, thereby improving the detection speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 This is a flow chart of Embodiment 1 of the present invention;

[0093] Figure 2 This is a structural block diagram of Embodiment 2 of the present invention;

[0094] Figure 3 This is a structural block diagram of embodiment 3 of the present invention.

[0095] In the figure, 1-threshold calculation unit, 2-data acquisition unit, 3-detection unit, 4-motor vehicle feature selection unit, 11-historical data preprocessing unit, 12-historical data screening unit, 13-pollutant emission concentration change rate threshold calculation unit, 14-engine oil temperature threshold calculation unit, 15-exhaust gas exhaust flow threshold calculation unit, 16-engine operating condition threshold calculation unit. DETAILED DESCRIPTION

[0096] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0097] Example 1

[0098] The embodiment of the present invention provides a method and system for detecting cheating behavior of exhaust gas detection for temporarily installing a three-way catalytic converter, such as Figure 1 As shown, it includes the following steps:

[0099] Step 1: Collect historical motor vehicle inspection data. Preprocess the historical motor vehicle inspection data, including checking data integrity and consistency, handling possible missing data, outliers or duplicate data; formatting and unifying timestamps to ensure the correctness and comparability of time series.

[0100] Step 2: Filter the historical data according to vehicle models, and then determine the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold of each vehicle model based on the historical data filtered out.

[0101] The vehicle model is determined by vehicle characteristics, and the vehicle characteristics include at least one of vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type.

[0102] The four thresholds can be set to reasonable values ​​as follows:

[0103] (1) The method for determining the pollutant emission concentration change rate threshold is to fit a linear regression model to the sampled values, limit the change range by setting the change rate threshold, and identify those detection records with more dramatic upward trends.

[0104] The sampling sequence (x 1 ,y 1 ),(x 2 ,y 2 ),…,(xi ,y i ), record y i is the pollutant concentration at the i-th time point, x i is the corresponding time point, which can be simplified to x i =1, a linear regression model is constructed for each pollutant emission concentration in the filtered historical data:

[0105] y i =β 0 +β 1 x i +∈ i

[0106] Where: β 0 is the intercept term, ∈ i is the error term, β 1 is the slope, which reflects the changing trend of pollutant concentration over time.

[0107] The pollutant emission concentration change rate threshold θ takes all β 1 The average value of .

[0108] The pollutants whose emission concentrations need to be detected include CO, NOx, etc., and the pollutant emission concentration change rate threshold θ needs to be calculated for each pollutant.

[0109] (2) The method for determining the engine oil temperature threshold is as follows: calculating the overall average value and standard deviation of the oil temperature data in the filtered historical data, and setting a threshold to filter out records with high oil temperature.

[0110] Let the set S 1i For all the filtered oil temperature values ​​in the historical data, calculate the overall average value:

[0111]

[0112] Then calculate the overall standard deviation:

[0113]

[0114] The engine oil temperature threshold is:

[0115] T 1 =μ 1 +2δ 1 .

[0116] (3) The method for determining the exhaust gas flow rate threshold is as follows: calculating the overall average value and standard deviation of the exhaust gas flow rate data in the filtered historical data, and setting a threshold to filter out records with high oil temperature.

[0117] Let the set S 2iFor all the filtered exhaust gas flow values ​​of the historical data, calculate the overall average value:

[0118]

[0119] Then calculate the overall standard deviation:

[0120]

[0121] The exhaust gas flow rate threshold is:

[0122] T 2 =μ 2 +2δ 2 .

[0123] (4) The method for determining the engine operating condition threshold is:

[0124] If the engine is turned off, its speed is 0. Accordingly, the engine operating condition threshold value Z is 0.

[0125] Step 3: Obtain the motor vehicle inspection process data, determine the vehicle model, and compare the motor vehicle inspection process data with the threshold values ​​of the pollutant emission concentration change rate, engine oil temperature, exhaust gas flow rate, and engine operating conditions of the vehicle model. If at least 3 of the inspection standards are met, it is determined that there is a suspicion of cheating by installing a temporary three-way catalytic converter. If only 0-2 of the inspection standards are met, it is determined that there is no suspicion of cheating by installing a temporary three-way catalytic converter.

[0126] The testing standards are:

[0127] a. The pollutant emission concentration change rate of the motor vehicle detection process data is higher than the pollutant emission concentration change rate threshold. This detection standard is used to determine whether the pollutant concentration has risen sharply. It should be noted that multiple pollutants need to be detected, and each pollutant corresponds to a pollutant emission concentration change rate threshold. When there is a pollutant emission concentration change rate that is higher than the pollutant emission concentration change rate threshold, it is considered that this detection standard is met.

[0128] b. The average value of the engine oil temperature of the motor vehicle detection process data is higher than the engine oil temperature threshold. This detection standard is used to determine that the engine oil temperature is too high.

[0129] c. The average exhaust gas flow rate of the motor vehicle detection process data is lower than the exhaust gas flow rate threshold. This detection standard is used to determine that the exhaust gas flow rate value is low.

[0130] d. The engine speed of the vehicle detection process data falls within the engine operating condition threshold, that is, the engine is turned off during the detection process. Under normal circumstances, the engine speed at any i-th time point in the sampling sequence of the vehicle detection process data should be greater than 0.

[0131] Step 4: Conduct manual direct inspection of vehicles suspected of cheating by installing temporary three-way catalytic converters to determine whether cheating has occurred. Perform manual re-inspection to identify the temporary three-way catalytic converters installed in the vehicles.

[0132] In order to verify the accuracy of this embodiment, the following experiments were conducted.

[0133] 1. Vehicle model selection: Vehicle brand: Volkswagen Passat, total mileage: 50,000-100,000 kilometers, engine model: EA888, engine displacement: 2.0T, drive type: front drive.

[0134] 2. Determine the threshold: Filter the historical data of motor vehicle detection according to the vehicle model, and then pre-process the data. After that, keep the 3,000 most recent historical data, and calculate the pollutant emission concentration change rate threshold, engine oil temperature threshold and exhaust gas flow threshold. Among them, there are three pollutant emission concentration change rate thresholds, corresponding to CO, HC and NOx respectively.

[0135] 3. Selection of motor vehicles: Since the test itself is harmful to motor vehicles, we only selected 10 motor vehicles of this model, denoted as A1-A10.

[0136] 4. Test 1: Motor vehicle exhaust gas testing was conducted on A1-A10 according to conventional methods. The motor vehicle testing process data was obtained and compared with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold. The results showed that A1-A10 did not meet any of the testing standards.

[0137] 5. Test 2: A "steel ball" coated with a small amount of three-way catalyst was installed inside the exhaust pipe of A1-A8, and a "steel ball" coated with a small amount of three-way catalyst was installed inside the three-way catalytic device of the motor vehicle of A9 and A10. Then, the motor vehicle exhaust gas detection of A1-A10 was carried out according to the conventional method, and the motor vehicle detection process data was obtained respectively, and compared with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas exhaust flow threshold and engine operating condition threshold. The results are shown in Table 1.

[0138] Table 1 Cheating behavior detection results

[0139] A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 Higher than the pollutant emission concentration change rate threshold √ √ √ √ √ √ √ √ √ √ Above engine oil temperature threshold √ × √ √ √ √ √ √ √ √ Below the exhaust gas flow threshold √ √ √ √ × √ √ √ × √ Falling within the engine operating condition threshold √ √ × × √ × × √ √ √

[0140] In addition, we also compared 3,000 historical data with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold. 42 data were higher than the pollutant emission concentration change rate threshold, 59 data were higher than the engine oil temperature threshold, 7 data were lower than the exhaust gas flow rate threshold, and 3 data were within the engine operating condition threshold. None of the historical data met at least 3 of the detection standards.

[0141] 6. Result analysis: This method detected all 10 vehicles with temporary three-way catalytic converters installed, with a detection accuracy of 100%. For the 3,000 vehicles without temporary three-way catalytic converters installed, no cheating was found. This method does not have missed detection or wrong detection, and can meet the detection requirements of temporary three-way catalytic converters.

[0142] Example 2

[0143] The embodiment of the present invention also provides a system for detecting cheating behavior of exhaust gas detection for temporarily installing a three-way catalytic converter, such as Figure 2 As shown, it includes a threshold calculation unit 1, a data acquisition unit 2 and a detection unit 3, and the detection unit 3 is connected to the threshold calculation unit 1 and the data acquisition unit 2 respectively.

[0144] The threshold calculation unit 1 is used to filter the motor vehicle detection historical data according to the vehicle model, and determine the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold of each vehicle model. The threshold calculation unit 1 communicates with the existing motor vehicle exhaust detection system, and can obtain the motor vehicle detection historical data stored in the motor vehicle exhaust detection system. After the motor vehicle detection historical data is preprocessed, the motor vehicle detection historical data is filtered according to the motor vehicle characteristics, and all historical data corresponding to a certain model are filtered out, and then the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold of the model are calculated based on the historical data. The motor vehicle characteristics, pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold corresponding to the model are transmitted to the detection unit 3. Since the motor vehicle detection historical data changes continuously with the increase in the number of motor vehicle detections, it is necessary to update it regularly and recalculate the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold of each model. The update cycle can be set to one day, one week or one month, etc.

[0145] The threshold calculation unit 1 includes a historical data preprocessing unit 11, a historical data screening unit 12, a pollutant emission concentration change rate threshold calculation unit 13, an engine oil temperature threshold calculation unit 14, an exhaust gas flow rate threshold calculation unit 15 and an engine operating condition threshold calculation unit 16. The historical data preprocessing unit 11 is connected to the historical data screening unit 12, and the historical data screening unit 12 is respectively connected to the pollutant emission concentration change rate threshold calculation unit 13, the engine oil temperature threshold calculation unit 14, the exhaust gas flow rate threshold calculation unit 15 and the engine operating condition threshold calculation unit 16.

[0146] The historical data preprocessing unit 11 preprocesses the motor vehicle detection historical data, and the preprocessing includes processing missing data, abnormal values ​​and repeated data, and formatting and unifying timestamps.

[0147] The historical data screening unit 12 screens the preprocessed motor vehicle detection historical data according to the vehicle model, and the vehicle model is determined by the motor vehicle characteristics, and the motor vehicle characteristics include at least one of the vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type.

[0148] The calculation process of the pollutant emission concentration change rate threshold value calculation unit 13 is:

[0149] The sampling sequence (x 1 ,y 1 ),(x 2 ,y 2 ),…,(x i ,y i ), record y i is the pollutant concentration at the i-th time point, x i For the corresponding time point, a linear regression model is constructed for each pollutant emission concentration in the filtered historical data:

[0150] y i =β 0 +β 1 x i +∈ i

[0151] Where: β 0 is the intercept term, ∈ i is the error term, β 1 is the slope,

[0152] Calculate all β 1 The average value of is taken as the pollutant emission concentration change rate threshold θ.

[0153] The calculation process of the engine oil temperature threshold value calculation unit 14 is:

[0154] Let the set S 1i For all the filtered oil temperature values ​​in the historical data, calculate the overall average value:

[0155]

[0156] Then calculate the overall standard deviation:

[0157]

[0158] The engine oil temperature threshold is:

[0159] T 1 =μ 1 +2δ 1 .

[0160] The calculation process of the exhaust gas flow rate threshold value calculation unit 15 is:

[0161] Let the set S 2i For all the filtered exhaust gas flow values ​​of the historical data, calculate the overall average value:

[0162]

[0163] Then calculate the overall standard deviation:

[0164]

[0165] The exhaust gas flow rate threshold is:

[0166] T 2 =μ 2 +2δ 2 .

[0167] The calculation process of the engine operating condition threshold value calculation unit 16 is:

[0168] If the engine is turned off, its speed is 0, and the engine operating condition threshold value Z is 0.

[0169] The data acquisition unit 2 is used to obtain data of a motor vehicle detection process. The data acquisition unit 2 communicates with the existing motor vehicle exhaust detection system to obtain a specific motor vehicle detection process data from the existing motor vehicle exhaust detection system.

[0170] The detection unit 3 is used to determine the vehicle model corresponding to the motor vehicle detection process data, and compare the motor vehicle detection process data with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold of the vehicle model to determine whether there is a suspicion of cheating by installing a temporary three-way catalytic converter.

[0171] After the data acquisition unit 2 obtains the motor vehicle detection process data from the motor vehicle exhaust detection system, it transmits it to the detection unit 3. The detection unit 3 determines the vehicle model corresponding to the motor vehicle detection process data according to the motor vehicle characteristics in the motor vehicle detection process data, and then retrieves the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas exhaust flow threshold and engine operating condition threshold corresponding to the vehicle model from the threshold calculation unit 1, and compares the motor vehicle detection process data with the above four thresholds of the vehicle model. If 4 or any 3 of the following four detection standards are met, it is determined that there is a suspicion of cheating behavior of installing a temporary three-way catalytic converter, and an alarm is issued to remind the detection personnel. The detection personnel will re-check and conduct manual direct review to verify whether the motor vehicle has cheating behavior, that is, whether a temporary three-way catalytic converter is installed in the motor vehicle.

[0172] The testing standards are:

[0173] a. the pollutant emission concentration change rate of the motor vehicle detection process data is higher than the pollutant emission concentration change rate threshold,

[0174] b. the average value of the engine oil temperature of the motor vehicle detection process data is higher than the engine oil temperature threshold,

[0175] c. the average exhaust gas flow rate of the motor vehicle detection process data is lower than the exhaust gas flow rate threshold,

[0176] d. The engine speed of the motor vehicle detection process data falls within the engine operating condition threshold.

[0177] Example 3

[0178] The embodiment of the present invention also provides a system for detecting cheating behavior of exhaust gas detection for temporarily installing a three-way catalytic converter, such as Figure 3 As shown, based on the second embodiment, it further includes a vehicle feature selection unit 4 , and the vehicle feature selection unit 4 is connected to the threshold value calculation unit 1 .

[0179] The motor vehicle feature selection unit 4 is used to determine the motor vehicle features with the least number corresponding to each vehicle model. The motor vehicle feature selection unit 4 adopts a fully connected neural network model, whose input is the preprocessed motor vehicle detection history data that does not meet at least 3 of the detection criteria, and its output is the motor vehicle features.

[0180] If the motor vehicle characteristics corresponding to a certain model include all of the vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type, the number of corresponding motor vehicle detection history data is relatively small, which affects the accuracy of the threshold. The motor vehicle characteristic selection unit 4 can reduce the number of motor vehicle characteristics corresponding to the model, expand the number of samples of motor vehicle detection history data in disguised form, and improve the accuracy of the pollutant emission concentration change rate threshold, engine oil temperature threshold, and exhaust gas flow threshold.

[0181] The motor vehicle detection historical data is input into the threshold calculation unit 1. After preprocessing, the motor vehicle detection historical data is screened according to the seven motor vehicle characteristics corresponding to a certain vehicle model (vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type), and then the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold, and engine operating condition threshold corresponding to the vehicle model are calculated.

[0182] The pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold corresponding to this vehicle model, as well as the pre-processed motor vehicle detection history data are transmitted to the motor vehicle feature selection unit 4. The motor vehicle feature selection unit 4 selects the motor vehicle detection history data that does not meet the four detection standards from the pre-processed motor vehicle detection history data as input, and after calculation by the fully connected neural network model, outputs the motor vehicle characteristics (less than seven in number) and transmits them to the threshold calculation unit 1.

[0183] The threshold calculation unit 1 matches the motor vehicle characteristics input from the motor vehicle characteristics selection unit 4 with the vehicle model, re-screens the motor vehicle detection history data, and then calculates the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold corresponding to the vehicle model. The motor vehicle characteristics, pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow rate threshold and engine operating condition threshold corresponding to the vehicle model are then transmitted to the detection unit 3.

[0184] Example 4

[0185] An embodiment of the present invention further provides a computer-readable storage medium, comprising a program, wherein the program can be executed by a processor to implement the above-mentioned method for detecting cheating behavior in exhaust gas detection for a temporarily installed three-way catalytic converter.

[0186] The present invention has been described in detail above through embodiments, but the contents described are only exemplary embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. The protection scope of the present invention is defined by the claims. Anyone who utilizes the technical solution described in the present invention, or a technician in the field, inspired by the technical solution of the present invention, designs a similar technical solution within the essence and protection scope of the present invention to achieve the above technical effects, or makes equal changes and improvements to the scope of application, etc., shall still fall within the scope of protection covered by the patent of the present invention.

Claims

1. A method for detecting cheating behavior in exhaust gas detection of a temporarily installed three-way catalytic converter, characterized in that: The following steps are involved: Step 1: Collect historical data on motor vehicle inspections; Step 2: Filter the historical data according to vehicle models, and then determine the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold for each vehicle model; Step 3: Obtain the vehicle detection process data, determine the vehicle model, and compare the vehicle detection process data with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold corresponding to the vehicle model. If at least three of the detection standards are met, it is determined that there is a suspicion of cheating by installing a temporary three-way catalytic converter. The testing standards are: a. the pollutant emission concentration change rate of the motor vehicle detection process data is higher than the pollutant emission concentration change rate threshold, b. the average value of the engine oil temperature of the motor vehicle detection process data is higher than the engine oil temperature threshold, c. the average exhaust gas flow rate of the motor vehicle detection process data is lower than the exhaust gas flow rate threshold, d. The engine is turned off during the test; The method for determining the pollutant emission concentration change rate threshold is: The sampling sequence (x1, y1), (x2, y2), ..., (x i ,y i ), record y i is the pollutant concentration at the i-th time point, x i For the corresponding time point, a linear regression model is constructed for each pollutant emission concentration in the filtered historical data: y i =β0+β1x i +∈ i Where: β0 is the intercept term, ∈ i is the error term, β1 is the slope, The pollutant emission concentration change rate threshold θ is the average value of all β1; The method for determining the engine oil temperature threshold is: Let the set S 1i For all the filtered oil temperature values ​​in the historical data, calculate the overall average value: Then calculate the overall standard deviation: The engine oil temperature threshold is: T1=μ1+2δ1; The method for determining the exhaust gas flow rate threshold is as follows: Let the set S 2i For all the filtered exhaust gas flow values ​​of the historical data, calculate the overall average value: Then calculate the overall standard deviation: The exhaust gas flow rate threshold is: T2=μ2+2δ2.

2. The method for detecting cheating behavior of exhaust gas detection for temporarily installed three-way catalytic converters according to claim 1, characterized in that: It also includes step 4: conducting manual direct inspection of motor vehicles suspected of cheating by installing a temporary three-way catalytic converter to determine whether cheating has occurred.

3. The method for detecting cheating behavior of exhaust gas detection for temporarily installed three-way catalytic converters according to claim 1 or 2, characterized in that: In step 1, the motor vehicle detection historical data is preprocessed, including processing missing data, outliers and duplicate data, and formatting and unifying timestamps.

4. The method for detecting cheating behavior of exhaust gas detection for temporarily installed three-way catalytic converters according to claim 1 or 2, characterized in that: The vehicle model is determined by vehicle characteristics, and the vehicle characteristics include at least one of vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type.

5. The exhaust gas detection cheating behavior detection system for temporarily installed three-way catalytic converters is characterized by: It includes a threshold calculation unit for screening the historical data of motor vehicle detection according to the vehicle model, and then determining the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold for each vehicle model; A data acquisition unit, used to obtain motor vehicle inspection process data; The detection unit is used to determine the vehicle model corresponding to the motor vehicle detection process data, and compare the motor vehicle detection process data with the pollutant emission concentration change rate threshold, engine oil temperature threshold, exhaust gas flow threshold and engine operating condition threshold of the vehicle model. If at least three of the detection standards are met, it is determined that there is a suspicion of cheating by installing a temporary three-way catalytic converter. The testing standards are: a. the pollutant emission concentration change rate of the motor vehicle detection process data is higher than the pollutant emission concentration change rate threshold, b. the average value of the engine oil temperature of the motor vehicle detection process data is higher than the engine oil temperature threshold, c. the average exhaust gas flow rate of the motor vehicle detection process data is lower than the exhaust gas flow rate threshold, d. The engine is turned off during the test; The calculation process of the pollutant emission concentration change rate threshold value calculation unit is as follows: The sampling sequence (x1, y1), (x2, y2), ..., (x i ,y i ), record y i is the pollutant concentration at the i-th time point, x i For the corresponding time point, a linear regression model is constructed for each pollutant emission concentration in the filtered historical data: y i =β0+β1x i +∈ i Where: β0 is the intercept term, ∈ i is the error term, β1 is the slope, Calculate the average value of all β1 as the pollutant emission concentration change rate threshold θ; The calculation process of the engine oil temperature threshold calculation unit is as follows: Let the set S 1i For all the filtered oil temperature values ​​in the historical data, calculate the overall average value: Then calculate the overall standard deviation: The engine oil temperature threshold is: T1=μ1+2δ1; The calculation process of the exhaust gas flow rate threshold value calculation unit is as follows: Let the set S 2i For all the filtered exhaust gas flow values ​​of the historical data, calculate the overall average value: Then calculate the overall standard deviation: The exhaust gas flow rate threshold is: T2=μ2+2δ2.

6. The exhaust gas detection cheating behavior detection system for temporarily installed three-way catalytic converters as claimed in claim 5, characterized in that: The detection unit is connected to the threshold calculation unit and the data acquisition unit respectively; The threshold calculation unit includes a historical data preprocessing unit, a historical data screening unit, a pollutant emission concentration change rate threshold calculation unit, an engine oil temperature threshold calculation unit, an exhaust gas flow rate threshold calculation unit and an engine operating condition threshold calculation unit, the historical data preprocessing unit is connected to the historical data screening unit, and the historical data screening unit is respectively connected to the pollutant emission concentration change rate threshold calculation unit, the engine oil temperature threshold calculation unit, the exhaust gas flow rate threshold calculation unit and the engine operating condition threshold calculation unit, The historical data preprocessing unit preprocesses the motor vehicle detection historical data, and the preprocessing includes processing missing data, abnormal values ​​and duplicate data, and formatting and unifying timestamps; The historical data screening unit screens the preprocessed motor vehicle detection historical data according to the vehicle model, and the vehicle model is determined by the motor vehicle characteristics, and the motor vehicle characteristics include at least one of the vehicle brand, total mileage, vehicle model, maximum total mass, engine model, engine displacement, and drive type.

7. The exhaust gas detection cheating behavior detection system for temporarily installed three-way catalytic converters as claimed in claim 6, characterized in that: It also includes a motor vehicle feature selection unit, which is used to determine the motor vehicle features with the least number corresponding to each vehicle model, and the motor vehicle feature selection unit is connected to the threshold calculation unit.

8. The exhaust gas detection cheating behavior detection system for temporarily installed three-way catalytic converters as claimed in claim 7, characterized in that: The motor vehicle feature selection unit adopts a fully connected neural network model, whose input is the preprocessed motor vehicle detection history data that does not meet the four detection standards, and whose output is the motor vehicle feature.

9. A computer-readable storage medium, characterized in that: The method comprises a program which can be executed by a processor to implement the exhaust gas detection cheating behavior detection method for temporarily installing a three-way catalytic converter as described in any one of claims 1 to 4.

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