Rapid detection method for nitrogen oxides in vehicle engine exhaust emissions

Abstract

The present invention discloses a rapid detection method for nitrogen oxides emitted from vehicle engine exhaust, relates to the field of exhaust gas detection technology, adopts free acceleration method, measures the nitrogen oxide content of vehicle engine; obtains the linear detection data of nitrogen oxide content of the whole process of engine acceleration from idle speed to rated speed in unit time; records the nitrogen oxide content value in the whole detection process, and makes corresponding graphics to analyze the nitrogen oxide content change trend; based on the vehicle type and detection standard built-in in the equipment supporting APP software, sets the effective value of engine exhaust temperature and exhaust wind speed monitoring. The portable nitrogen oxide detector of the present invention uses the in-situ free acceleration method (GB3847-2018 standard Appendix A) to measure the nitrogen oxide content of automobile engine exhaust emissions. The full detection cycle does not exceed three minutes, which improves the efficiency of detection and is convenient for law enforcement departments to implement road inspections at intersections with large traffic volume.

Description

Technical Field

[0001] The present invention belongs to the environmental protection industry and relates to the field of exhaust gas detection technology, especially the field of exhaust gas detection technology for compression ignition (including non-road mobile machinery) vehicles and spark-ignition vehicles (mainly fueled by natural gas and petroleum gas), and specifically relates to a method for rapid detection of nitrogen oxides emitted from vehicle engine exhaust. Background Art

[0002] According to GB17691-2018, GB3847-2018, GB18285-2018 and other standards, the exhaust pollutants "nitrogen oxides" of compression ignition and spark ignition engines need to be tested. The national standards stipulate emission limits, measurement methods and test methods. Among them, vehicle testing agencies use the "loaded deceleration method" specified in the "GB3847-2018 Diesel Vehicle Pollutant Emission Limits and Measurement Methods (Free Acceleration Method and Loaded Deceleration Method)" standard to measure the nitrogen oxide content emitted by diesel vehicles. Vehicle testing agencies use

[0003] The "steady-state operating method" specified in the "GB18285-2018 Gasoline Vehicle Pollutant Emission Limits and Measurement Methods (Dual Idle Method and Simple Operating Condition Method)" standard measures the nitrogen oxide content emitted by gas vehicles;

[0004] The "on-vehicle road test method" specified in the standard "DB11 / 1476-2017 Rapid Detection Method and Emission Limits for Nitrogen Oxides of Heavy-Duty Vehicles" measures the nitrogen oxide content emitted by diesel vehicles and gas vehicles; some ecological and environmental law enforcement departments use the "remote sensing method" specified in the standard "HJ845-2017 Measurement Method and Technical Requirements for Exhaust Pollutants of In-Use Diesel Vehicles (Remote Sensing Monitoring Method)" to measure the nitrogen oxide content emitted by diesel vehicles and gas vehicles.

[0005] The prior art has the following disadvantages:

[0006] 1. Vehicle inspection agencies use the "loaded deceleration method" specified in the "GB3847-2018 Diesel Vehicle Pollutant Emission Limits and Measurement Methods (Free Acceleration Method and Loaded Deceleration Method)" standard. This test requires an external 220V power supply and a chassis dynamometer. This test can only be used by vehicle inspection agencies with fixed sites and is not suitable for random road inspections or home inspections.

[0007] 2. Vehicle inspection agencies use the "steady-state operating method" specified in the "GB18285-2018 Gasoline Vehicle Pollutant Emission Limits and Measurement Methods (Dual Idle Method and Simple Operating Condition Method)" standard. This requires an external 220V power supply and a chassis dynamometer. This method can only be used by vehicle inspection agencies with fixed sites and is not suitable for random road inspections or home inspections.

[0008] 3. The "on-board road test method" adopted in the DB11 / 1476-2017 Heavy-Duty Vehicle Nitrogen Oxide Rapid Test Method and Emission Limits standard requires installation personnel to install the equipment during testing, and the test personnel must accompany the vehicle. After the test, the equipment must be disassembled and transported back to the test starting point. This requires a lot of personnel, and the total test cycle is too long, which is inefficient and not suitable for random road inspections and home inspections. In addition, the test equipment must be loaded onto the vehicle and driven for more than 2,000 meters. During the test, the road conditions must be smooth and there must be no ups and downs. The vehicle must maintain a constant speed and no operations such as shifting gears or increasing or decreasing the throttle must be performed. In actual testing, the test site is difficult to determine, making it unsuitable for random road inspections and home inspections.

[0009] 4. Using the remote sensing method specified in the "HJ845-2017 Measurement Method and Technical Requirements for Exhaust Pollutants from In-Use Diesel Vehicles (Remote Sensing Monitoring Method)" standard issued by the Ministry of Ecology and Environment, the detection equipment must be fixed on the side of the road to detect a specific emission value of passing vehicles (point detection). When passing vehicles are driving in neutral or loaded, the probability of misjudgment is very high, and it is not suitable for random road inspections and home inspections;

[0010] 5. The four existing detection technologies can only measure the actual peak value of nitrogen oxides, and the existing national standards for nitrogen oxide limits are too loose (Article 03 of the summary of the "2020 Green Card List" jointly released by the Motor Vehicle Emission Monitoring Center of the Institute of Environmental Sciences, the Asia Clean Air Center, and the School of Environment of Tsinghua University states that "the nitrogen oxide limit for the annual environmental inspection of in-use diesel trucks needs to be tightened; the current loading and deceleration method NOX limit a (1500ppm) for the annual environmental inspection is insufficient to screen out high-emission vehicles"). It cannot screen out high-emission vehicles, let alone distinguish between behaviors such as falsification of vehicle pollution control devices and blocking of OBD functions. Summary of the Invention

[0011] The present invention aims to provide a method for rapidly detecting nitrogen oxides emitted from vehicle engine exhaust to solve the problems raised in the above-mentioned background technology.

[0012] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0013] A method for rapidly detecting nitrogen oxides emitted from vehicle engine exhaust comprises the following steps:

[0014] Step 1: Use the free acceleration method to measure the nitrogen oxide content of the vehicle engine;

[0015] Step 2: Obtain linear detection data of nitrogen oxide content during the entire process of engine acceleration from idle to rated speed within a unit time, wherein idle speed is one revolution, rated speed is three revolutions, and the unit time is 10 seconds for the loading and holding phase and 10 seconds for the unloading and holding phase;

[0016] Step 3: Record the nitrogen oxide content values ​​throughout the entire testing process, create corresponding graphs, and analyze the changing trend of nitrogen oxide content;

[0017] Step 4: Based on the vehicle type and detection standards built into the device's APP software, set the effective values ​​for engine exhaust temperature and exhaust wind speed monitoring;

[0018] Step 5: Using the AI ​​recognition function built into the device's accompanying app software, it automatically determines that the vehicle's exhaust emissions are within the permitted limits but that there are violations. These violations include falsifying vehicle pollution control devices and blocking the OBD function.

[0019] Step 6. Generate a PDF file for archiving in real time based on the test records, and upload the test data to the cloud platform and the regulatory department data platform in real time.

[0020] A further improvement of the technical solution of the present invention is that in step 1, the process of measuring the nitrogen oxide content of the vehicle engine includes:

[0021] Enter the vehicle information of the vehicle to be inspected, including the vehicle model, vehicle identification code, and engine model, so that a dedicated inspection route can be automatically assigned. The vehicle to be inspected should be parked in a safe area without turning off the engine. Before the inspection, the engine should be hot and in good mechanical condition.

[0022] Before testing, the exhaust system is pre-treated by blowing through the exhaust system using three free acceleration processes or other equivalent methods to remove residual pollutants in the exhaust system. Exhaust system pre-treatment shall be implemented in accordance with the provisions of Clause A.3.3 of Appendix A of GB3847-2018;

[0023] After preheating the nitrogen oxide detector, insert the sampling tube of the nitrogen oxide detector into the exhaust pipe of the vehicle or engine. The nitrogen oxide detector is a portable nitrogen oxide detector manufactured using a high-sensitivity automotive nitrogen oxide sensor based on electrochemical principles.

[0024] Open the device's accompanying app and select the vehicle type and testing standard applicable to the vehicle being tested (e.g., for road inspections of diesel vehicles meeting the China VI emission standards, select "Vehicle Type: China VI Diesel Vehicle" and "Testing Standard: Rapid Testing Method"; for household inspections of non-road mobile machinery meeting the China III emission standards, select "Vehicle Type: China III Non-road Mobile Machinery" and "Testing Standard: Free Acceleration Method");

[0025] Based on the nitrogen oxide detector, the in-situ free acceleration method (Appendix A of the "GB3847-2018 Diesel Vehicle Pollutant Emission Limits and Measurement Methods (Free Acceleration Method and Loaded Deceleration Method)" standard) is used to measure the nitrogen oxide content in automobile engine exhaust emissions.

[0026] A further improvement of the technical solution of the present invention is that in step 2, the process of obtaining the linear detection data of nitrogen oxide content includes:

[0027] Start the engine, preheat the engine to an oil temperature of 80°C, and monitor the engine speed throughout the process;

[0028] In accordance with the operating standards of GB18285-2018, operate according to the prompts in the equipment APP software. When the APP prompts the loading countdown, press the accelerator pedal to the bottom within 1 second (the engine speed is at least increased to the rated speed). When the APP prompts the unloading countdown, release the accelerator pedal completely. Repeat the loading and unloading process three times to form a complete test cycle.

[0029] The measurement includes linear detection data of nitrogen oxide content during the entire process of engine acceleration from idle speed to rated speed in the unit time of 10 seconds in the loading and holding stage and 10 seconds in the unloading and holding stage, where idle speed is one rotation and rated speed is three rotations.

[0030] A further improvement of the technical solution of the present invention is that in step 3, the process of analyzing the trend of change in nitrogen oxide content includes:

[0031] Analyze the nitrogen oxide values ​​of engine emissions recorded by the APP software, including the nitrogen oxide content at idle and rated speed;

[0032] Make the recorded nitrogen oxide content values ​​into line graphs / curve graphs / trend graphs / distribution graphs and other graphics;

[0033] By graphically analyzing the changing trend of nitrogen oxide content, the difference in nitrogen oxide content at idle speed and rated speed, as well as the nitrogen oxide emission results at different emission stages, are observed. Among them, the nitrogen oxide emission results at different emission stages include the peak value at idle speed and the peak value at rated speed.

[0034] A further improvement of the technical solution of the present invention is that in step 4, the process of setting the effective monitoring values ​​of the engine exhaust temperature and exhaust wind speed includes:

[0035] Based on the analysis results of the changing trend of nitrogen oxide content, the equipment's supporting APP software automatically identifies invalid measurements. Invalid measurements include engine exhaust temperature and engine exhaust wind speed that do not meet the standard. Exhaust temperature that does not meet the standard will result in urea not being sprayed or decomposed in diesel vehicles, urea not reacting in the three-way catalytic converter of gas vehicles, and engine exhaust wind speed that does not meet the standard, making it impossible to measure the actual emission value at the rated speed.

[0036] Analyze the temperature measured by the engine exhaust monitoring, the ratio to the temperature before the engine exhaust pipe and the SCR temperature, and clarify the effective values ​​of the engine exhaust temperature and exhaust wind speed monitoring for the nitrogen oxide content test to ensure that the SCR urea injection system is in normal working condition.

[0037] A further improvement of the technical solution of the present invention is that: for the engine exhaust temperature, the effective value of the engine exhaust temperature monitoring is set as follows: when the ambient temperature is ≥15°C, the exhaust temperature is ≥90°C; when the ambient temperature is <15°C, the exhaust temperature is ≥70°C, and the test results above this temperature are considered valid;

[0038] For the engine exhaust wind speed, the effective value of the engine exhaust wind speed monitoring is set to: the wind speed at rated speed ≥ 3 times the wind speed at idle speed, and the test results above this multiple are considered valid.

[0039] A further improvement of the technical solution of the present invention is that in step 5, the process of determining the violation includes:

[0040] The AI ​​recognition function built into the APP software analyzes the collected nitrogen oxide content values ​​and automatically determines whether the exhaust emissions exceed the standard;

[0041] If the exhaust emissions do not exceed the standard, the AI ​​automatically determines whether there is any blocking or program tampering by analyzing the trend of changes in nitrogen oxide content. Specifically, it determines whether the front temperature sensor is raised so that the vehicle does not inject urea when idling; whether the front and rear nitrogen oxide sensors of the SCR system are removed, a nitrogen oxide simulator is used, and the OBD torque limit function is turned off so that the vehicle does not inject urea; whether the urea injection pump and urea level sensor of the SCR system are removed or turned off, and the OBD torque limit function is turned off so that the vehicle does not inject urea; whether a urea solution lower than the national standard is used, and whether the OBD reduces the urea injection amount, etc., so as to reduce the vehicle's urea consumption and reduce vehicle use costs;

[0042] Based on the classification standards for vehicles in the National V and National VI emission stages, effective values ​​are set to determine whether diesel and gas vehicles have falsified pollution control devices or OBD.

[0043] A further improvement of the technical solution of the present invention is that for diesel vehicles meeting the National V emission standard, if the nitrogen oxide emission peak value at idle speed is ≥300ppm and the nitrogen oxide emission peak value at rated speed is ≥600ppm, it is determined to be OBD fraud;

[0044] For diesel vehicles in the National V emission stage, if the peak nitrogen oxide emissions at idle speed are ≥300ppm and the peak nitrogen oxide emissions at rated speed are ≤600ppm, it is determined that the vehicle pollution control device is falsified;

[0045] For diesel vehicles in the China VI emission stage, if the peak nitrogen oxide emissions at idle speed are ≥200ppm and the peak nitrogen oxide emissions at rated speed are ≥500ppm, it is determined to be OBD fraud;

[0046] For gas vehicles in the National VI emission stage, if the peak nitrogen oxide emission is ≥900ppm at the rated speed, it is determined that the pollution control device is falsified.

[0047] A further improvement of the technical solution of the present invention is that in step 6, the process of uploading the detection data in real time includes:

[0048] Integrate vehicle engine inspection records, automatically generate inspection reports, and save the inspection reports in PDF format;

[0049] Write a data upload program based on the API provided by the cloud platform, read the test data, package it according to the format required by the cloud platform, and upload it to the cloud platform for storage and processing for subsequent analysis and query;

[0050] According to the requirements of the regulatory authorities, the test data is formatted and packaged to ensure that the data meets the acceptance standards of the regulatory authorities, and the packaged data is uploaded to the data platform of the provincial and municipal ecological environment management departments.

[0051] Due to the adoption of the above technical solution, the present invention has the following technical advancements compared to the prior art:

[0052] 1. The present invention provides a method for rapid detection of nitrogen oxides emitted from vehicle engine exhaust. The portable nitrogen oxide detector uses a built-in battery, which improves the applicability of the device in all scenarios and facilitates law enforcement agencies to implement road inspections and household inspections.

[0053] 2. The present invention provides a method for rapid detection of nitrogen oxides emitted from vehicle engine exhaust. The portable nitrogen oxide detector uses the in-situ free acceleration method (Appendix A of GB3847-2018 standard) to measure the nitrogen oxide content in automobile engine exhaust emissions. The entire detection cycle does not exceed three minutes, which improves the efficiency of detection and facilitates law enforcement agencies to carry out road inspections at intersections with heavy traffic.

[0054] 3. The present invention provides a method for rapid detection of nitrogen oxides emitted from vehicle engine exhaust. The portable nitrogen oxide detector uses a dedicated APP software that comes with the device and has built-in standards to automatically determine whether the nitrogen oxides emitted from the engine exhaust exceed the standard. The built-in AI recognition function can automatically determine whether the vehicle exhaust emissions do not exceed the standard, but there are behaviors such as falsification of vehicle pollution control devices and shielding of OBD functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0056] Figure 1 Schematic diagram of the process of the present invention;

[0057] Figure 2 This is the nitrogen oxide emission diagram of the National Five diesel vehicle that meets the emission standards of the present invention;

[0058] Figure 3 This is a fake diagram of the National Five diesel vehicle pollution control device of the present invention (the front temperature sensor is raised);

[0059] Figure 4 This is the fake OBD pollution map of the National Five diesel vehicle of the present invention (low effective urea injection volume);

[0060] Figure 5 This is the nitrogen oxide emission diagram of the National VI diesel vehicle that meets the emission standards of the present invention;

[0061] Figure 6 This is the fake OBD image of pollution for a China VI diesel vehicle (low effective urea injection volume);

[0062] Figure 7 This is the nitrogen oxide emission diagram of the National VI natural gas vehicle that meets the emission standards of the present invention;

[0063] Figure 8 This is a diagram of nitrogen oxide emissions from a National VI natural gas vehicle that exceeds the emission standard. DETAILED DESCRIPTION

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0065] Example 1, as Figure 1 As shown, the present invention provides a method for rapid detection of nitrogen oxides emitted from vehicle engine exhaust, comprising the following steps:

[0066] Step 1: Use the free acceleration method to measure the nitrogen oxide content of the vehicle engine, enter the vehicle information of the vehicle to be tested, including the vehicle model, vehicle identification code and engine model, so as to automatically assign a dedicated test line, park the vehicle to be tested in a safe area, do not shut down the engine, and before the test, make the engine in a hot state and in good mechanical condition. Before the test, use three free acceleration processes or other equivalent methods to blow the exhaust system for pretreatment of the exhaust system to clear residual pollutants in the exhaust system. The exhaust system pretreatment shall be implemented in accordance with the provisions of Clause A.3.3 in Appendix A of GB3847-2018. After preheating the nitrogen oxide detector, insert the sampling tube of the nitrogen oxide detector into the exhaust pipe of the vehicle or engine. The nitrogen oxide detector is a portable nitrogen oxide detector manufactured using a high-sensitivity automotive nitrogen oxide sensor based on electrochemical principles. , open the APP software that comes with the equipment, and select the vehicle type and test standard applicable to the vehicle being tested (e.g., for road inspections of diesel vehicles in the National VI emission stage, select "Vehicle Type: National VI Diesel Vehicle" and "Test Standard: Rapid Test Method"; for household spot checks of non-road mobile machinery in the National III emission stage, select "Vehicle Type: National III Non-road Mobile Machinery" and "Test Standard: Free Acceleration Method"). The software name is: Hangzhou Yuyang Environmental Protection, and the APP filing number is: Zhejiang ICP filing number 2024089450. The main functions are: collecting data from the nitrogen oxide detector, automatically determining the data, automatically generating a report, and uploading it to the cloud platform. Based on the nitrogen oxide detector, the in-situ free acceleration method (Appendix A of the "GB3847-2018 Diesel Vehicle Pollutant Emission Limits and Measurement Methods (Free Acceleration Method and Loaded Deceleration Method)" standard) is used to measure the nitrogen oxide content in automobile engine exhaust emissions.

[0067] Step 2. Obtain linear detection data of nitrogen oxide content in the whole process of engine acceleration from idle speed to rated speed within unit time, wherein idle speed is one rotation, rated speed is three rotations, unit time is 10 seconds for loading and holding stage, and 10 seconds for unloading and holding stage, start the engine, preheat the engine to the oil temperature of 80°C, and monitor the engine speed throughout the process, in combination with the operating standard of GB18285-2018, operate according to the prompt requirements in the equipment supporting APP software, according to the loading countdown prompted by the APP software, press the accelerator pedal to the bottom within 1 second (the engine speed is at least increased to the rated speed), the APP software prompts the unloading countdown, and the accelerator pedal needs to be completely released, repeat the loading and unloading process three times to constitute a complete detection cycle, and measure the linear detection data of nitrogen oxide content in the whole process of engine acceleration from idle speed to rated speed within the unit time of 10 seconds for loading and holding stage, and 10 seconds for unloading and holding stage, wherein idle speed is one rotation, and rated speed is three rotations;

[0068] Step 3. Record the nitrogen oxide content values ​​throughout the entire testing process and create corresponding graphs to analyze the changing trends of the nitrogen oxide content. Analyze the nitrogen oxide values ​​emitted by the engine as recorded by the APP software, including the nitrogen oxide content at idle and rated speed. Create a line graph / curve graph / trend graph / distribution graph of the recorded nitrogen oxide content values. Analyze the changing trends of the nitrogen oxide content through the graphs, observe the difference in nitrogen oxide content at idle and rated speed, and observe the nitrogen oxide emission results at different emission stages, including the peak values ​​at idle and rated speed.

[0069] Step 4. Based on the vehicle type and test standard built into the equipment supporting APP software, set the effective values ​​of engine exhaust temperature and exhaust wind speed monitoring. Based on the analysis results of the trend of nitrogen oxide content changes, use the equipment supporting APP software to automatically identify invalid measurements, where invalid measurements include engine exhaust temperature and engine exhaust wind speed that do not meet the standards. Substandard exhaust will result in diesel vehicle urea not being sprayed or urea not being decomposed, gas vehicle three-way catalytic converter not reacting, engine exhaust wind speed not meeting the standards, and the actual emission value at rated speed cannot be measured (see patent: Patent No. ZL202221773947.2 for details). Analyze the temperature measured by the engine exhaust monitoring and the ratio corresponding to the temperature before the engine exhaust pipe and the SCR temperature, and clarify the effective values ​​of the engine exhaust temperature and exhaust wind speed monitoring for the nitrogen oxide content test to ensure that the SCR urea injection system is in normal working condition.

[0070] Furthermore, for engine exhaust temperature, the effective value of engine exhaust temperature monitoring is set as follows: when the ambient temperature is ≥15°C, the exhaust temperature is ≥90°C; when the ambient temperature is <15°C, the exhaust temperature is ≥70°C. Detection results above this temperature are considered valid.

[0071] For engine exhaust wind speed, the effective value of engine exhaust wind speed monitoring is set as: wind speed at rated speed ≥ 3 times of wind speed at idle speed, and test results above this multiple are considered valid;

[0072] Step 5. Based on the built-in AI recognition function of the device's supporting APP software, it is automatically determined that the vehicle's exhaust emissions do not exceed the standard but there are violations. Among them, violations include falsification of vehicle pollution control devices, blocking of OBD functions, etc. The collected nitrogen oxide content values ​​are analyzed through the built-in AI recognition function of the APP software to automatically determine whether the exhaust emissions exceed the standard. If the exhaust emissions do not exceed the standard, by analyzing the trend of changes in nitrogen oxide content, AI automatically determines whether there is any shielding or tampering with the program, including: whether the front temperature sensor is raised to make the vehicle idle Whether the front and rear nitrogen oxide sensors of the SCR system are removed, a nitrogen oxide simulator is used, and the OBD torque limit function is turned off so that the vehicle does not inject urea; whether the urea injection pump and urea level sensor of the SCR system are removed or turned off, and the OBD torque limit function is turned off so that the vehicle does not inject urea; whether a urea solution lower than the national standard requirements is used, and the urea injection amount is reduced by OBD, so as to reduce the vehicle's urea consumption and reduce the cost of using the vehicle; based on the classification standards for vehicles in the National V and National VI emission stages, set the effective values ​​for whether diesel and gas vehicles have falsified pollution control devices and OBD falsification;

[0073] Furthermore, for diesel vehicles in the National V emission stage, if the nitrogen oxide emission peak value at idle speed is ≥300ppm and the nitrogen oxide emission peak value at rated speed is ≥600ppm, it is determined to be OBD fraud;

[0074] For diesel vehicles in the National V emission stage, if the peak nitrogen oxide emissions at idle speed are ≥300ppm and the peak nitrogen oxide emissions at rated speed are ≤600ppm, it is determined that the vehicle pollution control device is falsified;

[0075] For diesel vehicles in the China VI emission stage, if the peak nitrogen oxide emissions at idle speed are ≥200ppm and the peak nitrogen oxide emissions at rated speed are ≥500ppm, it is determined to be OBD fraud;

[0076] For gas vehicles meeting the China VI emission standards, if the peak nitrogen oxide emissions at the rated speed are ≥900ppm, it is determined that the pollution control device is falsified;

[0077] Step 6. Generate PDF files in real time based on the inspection records for archiving, upload the inspection data to the cloud platform and the regulatory department data platform synchronously in real time, integrate the vehicle engine inspection records, automatically generate the inspection report, and save the inspection report in PDF format. Write a data upload program based on the API provided by the cloud platform, read the inspection data, package it according to the format required by the cloud platform, and upload it to the cloud platform for storage and processing for subsequent analysis and query. According to the requirements of the regulatory department, convert and package the inspection data to ensure that the data meets the acceptance standards of the regulatory department, and upload the packaged data to the data platform of the provincial and municipal ecological environment management departments.

[0078] Example 2, as Figures 2 to 6 As shown, based on Example 1, the present invention provides a technical solution: preferably, the following is an example of a rapid detection technology for exhaust nitrogen oxides of a compression ignition engine (most vehicles use diesel fuel, and a small number of vehicles use methanol fuel) (hereinafter taking diesel fuel as an example):

[0079] First, the principle of nitrogen oxide emissions from compression ignition engine exhaust is as follows:

[0080] ⑴ Combustion process: When burning in the engine, fuel and air are mixed under high temperature and high pressure. Nitrogen is the main component of the air and participates in the combustion process after being compressed and burned.

[0081] ⑵ Nitrogen oxides (NOx) generation: During the combustion process, nitrogen and oxygen react chemically to produce a series of nitrogen oxides, mainly including nitrogen monoxide (NO) and nitrogen dioxide (NO2). The higher the temperature inside the engine, the more nitrogen oxides are generated;

[0082] (3) Nitrogen oxide emissions: Incomplete combustion in the engine and nitrogen oxidation reactions under high temperature and high pressure conditions generate excessive nitrogen oxides, which are emitted into the atmosphere, forming nitrogen oxide pollution in automobile exhaust;

[0083] Furthermore, the general technical principles for reducing nitrogen oxide emissions from compression ignition engine exhaust are briefly described as follows:

[0084] The key points of using SCR (Selective Catalytic Reduction) urea injection system to reduce vehicle nitrogen oxide emissions are:

[0085] (1) When the front temperature sensor of the diesel engine exhaust pipe detects that the temperature reaches 200°C, the urea pump starts to spray urea;

[0086] ⑵ Urea decomposes into ammonia under high temperature environment and mixes with nitrogen oxides in exhaust gas;

[0087] (3) In the SCR carrier, ammonia reacts with nitrogen oxides to produce nitrogen and water;

[0088] (4) The operating temperature of SCR catalytic reduction is 250-450℃, and the optimal operating temperature is 350℃;

[0089] 5. When the sensors of the SCR urea injection system detect an abnormality, the vehicle's torque will be limited, significantly reducing the vehicle's output power;

[0090] Therefore, to ensure the operation of the SCR urea injection system of diesel vehicles, two necessary conditions are required: the front temperature sensor detects 200℃ and starts to inject urea; the temperature inside the SCR carrier reaches 250℃ and starts catalytic reduction;

[0091] Furthermore, the main purpose of falsifying diesel engine exhaust pollution control devices and shielding OBD functions is to reduce the amount of urea injection or shut down urea injection through various technical means and human intervention to reduce the cost of use. The main means include:

[0092] ⑴ Raise the front temperature sensor so that urea is not sprayed when the vehicle is idling;

[0093] (2) Remove the front and rear nitrogen oxide sensors of the SCR system, use a nitrogen oxide simulator, turn off the OBD torque limit function, and prevent the vehicle from injecting urea;

[0094] (3) Remove or turn off the urea injection pump and urea level sensor of the SCR system, and turn off the OBD torque limit function so that the vehicle does not inject urea;

[0095] (4) Use urea solution lower than national standards, reduce urea injection volume through OBD, etc., so as to reduce vehicle urea consumption and reduce vehicle use costs;

[0096] Furthermore, the technical verification of rapid detection of nitrogen oxides in diesel engine exhaust emissions is as follows:

[0097] (1) Verification of diesel engine exhaust temperature monitoring: It is necessary to verify the ratio of the temperature measured by the engine exhaust monitoring to the temperature before the engine exhaust pipe and the SCR temperature to ensure that the SCR is working normally above a certain exhaust monitoring temperature;

[0098] After on-site road inspections in Henan, Hebei, Shanxi and other places, a total of 102 diesel vehicles of various types were tested. The test results range is shown in the table below (unit: °C)

[0099]

[0100]

[0101] It can be concluded that when the ambient temperature is ≥15℃ and the exhaust gas temperature is ≥90℃; when the ambient temperature is <15℃ and the exhaust gas temperature is ≥70℃, the SCR is in normal working condition.

[0102] Therefore, the effective value of engine exhaust temperature monitoring can be set as follows: when the ambient temperature is ≥15℃, the exhaust temperature is ≥90℃; when the ambient temperature is <15℃, the exhaust temperature is ≥70℃. The test results above this temperature are considered valid.

[0103] ⑵Verification of diesel engine wind speed monitoring:

[0104] According to mathematical formula, when the engine displacement and the diameter of the engine exhaust pipe are determined, the exhaust wind speed of the engine is directly proportional to the engine speed. For example, when the engine idle speed is 800 rpm and the rated speed is 2200 rpm, the rated speed of the engine is about 3 times the idle speed.

[0105] Therefore, the effective value of engine exhaust wind speed monitoring can be set as: wind speed at rated speed ≥ 3 times of wind speed at idle speed, and the test results above this multiple are considered valid;

[0106] ⑶Verification of nitrogen oxide detection of diesel engine exhaust emissions:

[0107] After on-site road inspections in Henan, Hebei, Shanxi and other places, a total of 102 diesel vehicles of various types were tested. The results of the nitrogen oxide emissions test are shown in the table below (unit × 10 -6 or ppm):

[0108]

[0109]

[0110] Note: The classification standards for vehicles in the National V and National VI emission stages are implemented in accordance with the provisions of GB17691-2005 and GB17691-2018 standards;

[0111] Therefore, the effective value for determining whether a diesel vehicle has fraudulent pollution control devices or OBD is set as:

[0112] Diesel vehicles meeting the National V emission standards have NOx emissions peak values ​​of 300ppm or higher at idle and 600ppm or higher at rated speed, indicating OBD fraud.

[0113] For diesel vehicles meeting the National V emission standards, the peak nitrogen oxide emissions at idle speed are ≥300ppm, and the peak nitrogen oxide emissions at rated speed are ≤600ppm, indicating that the vehicle pollution control device is falsified;

[0114] For diesel vehicles in the National VI emission stage, the peak nitrogen oxide emissions at idle speed are ≥200ppm, and the peak nitrogen oxide emissions at rated speed are ≥500ppm, which is confirmed to be OBD falsification.

[0115] Example 3, as Figure 7 、 Figure 8 As shown, based on Examples 1-2, the present invention provides a technical solution: preferably, the following is an example of a rapid detection technology for exhaust nitrogen oxides of spark-ignition engines (most vehicles use natural gas as fuel, and a small number of vehicles use petroleum gas as fuel, collectively referred to as gas engines) (hereinafter taking natural gas as an example):

[0116] First of all, the principle of nitrogen oxide emission from gas vehicle engine exhaust is as follows:

[0117] The principle of nitrogen oxide emissions from gas engine exhaust is similar to that of diesel engines. Since the temperature inside the engine cylinder of a gas engine during normal operation is higher than that of a diesel engine, the total amount of nitrogen oxides emitted by a gas engine is much higher than that of a diesel engine with the same displacement.

[0118] Furthermore, the technical principles for reducing nitrogen oxide emissions from gas vehicle engine exhaust are as follows:

[0119] ⑴ Enhance gas activity: When high-temperature automobile exhaust passes through the three-way catalytic converter, the internal purifier will enhance the activity of CO, HC and NOx;

[0120] ⑵Redox reaction: At high temperature, platinum-palladium catalyzes the oxidation of CO into CO2, HC compounds into water and carbon dioxide, and rhodium catalyzes the reduction of NOx into nitrogen;

[0121] Vehicles meeting the National V emission standards and below (e.g., National IV gasoline-to-gas conversion) have only platinum and palladium precious metal coatings in their exhaust after-treatment devices, but no rhodium precious metal coatings. Therefore, nitrogen oxides emissions at the National V emission standards and below are not reduced, resulting in very high nitrogen oxide emissions.

[0122] Vehicles meeting the China VI emission standards have platinum, palladium and rhodium precious metal coatings in their exhaust after-treatment devices, significantly reducing nitrogen oxide emissions.

[0123] The effective operating temperature of the three-way catalytic converter is 250°C, and the optimal operating temperature is 400°C;

[0124] Therefore, to ensure the operation of the three-way catalytic converter of a gas vehicle, two necessary conditions are required: the presence of rhodium metal in the catalyst; the temperature inside the catalyst reaches 250°C and catalytic reduction begins;

[0125] Furthermore, the main purpose of falsifying the exhaust pollution control device of gas vehicles (currently gas vehicles have no exhaust monitoring function on OBD) is to remove or replace substandard three-way catalytic converters in vehicles meeting the China VI emission standards in order to reduce the cost of use.

[0126] Furthermore, the technical verification of rapid detection of nitrogen oxides in exhaust emissions from gas vehicle engines is as follows:

[0127] ⑴ Verification of gas vehicle engine exhaust temperature monitoring:

[0128] Similar to diesel vehicles, the effective value of engine exhaust temperature monitoring can be set as follows: ambient temperature ≥ 15°C, exhaust temperature ≥ 90°C; ambient temperature < 15°C, exhaust temperature ≥ 70°C, and test results above this temperature are considered valid;

[0129] ⑵ Verification of gas vehicle engine wind speed monitoring:

[0130] Similar to diesel vehicles, the effective value of engine exhaust wind speed monitoring can be set as follows: wind speed at rated speed ≥ 3 times the wind speed at idle speed, and test results above this multiple are considered valid;

[0131] ⑶ Verification of nitrogen oxide detection in exhaust emissions from gas vehicle engines:

[0132] After on-site road inspections in Henan, Hebei, Shanxi and other places, a total of 57 gas vehicles with China VI emission standards were tested. The results of the nitrogen oxide emissions test are shown in the table below (unit × 10 -6 or ppm):

[0133]

[0134]

[0135] Therefore, the effective value for determining whether a gas vehicle has a pollution control device is set to:

[0136] The peak nitrogen oxide emission of gas vehicles in the National VI emission stage at the rated speed is ≥900ppm, which is determined to be a falsified pollution control device.

[0137] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A rapid detection method for nitrogen oxides emitted from vehicle engine exhaust, characterized in that: The following steps are involved: Step 1: Use the free acceleration method to measure the nitrogen oxide content of the vehicle engine; Step 2: Obtain linear detection data of nitrogen oxide content during the entire process of engine acceleration from idle speed to rated speed within a unit time; Step 3: Record the nitrogen oxide content during the entire testing process and generate corresponding graphs to analyze the changing trend of nitrogen oxide content; Step 4: Based on the vehicle type and detection standards built into the device's APP software, set the effective values ​​for engine exhaust temperature and exhaust wind speed monitoring; Step 5: Using the AI ​​recognition function built into the device's accompanying app software, it automatically determines that the vehicle's exhaust emissions are within the permitted limits but that violations exist. These violations include falsifying vehicle pollution control devices and blocking the OBD function. Step 6: Generate a PDF file based on the test records in real time for archiving, and upload the test data to the cloud platform and the regulatory department's data platform in real time; In step 3, the process of analyzing the change trend of nitrogen oxide content includes: Analyze the nitrogen oxide values ​​of engine emissions recorded by the APP software, including the nitrogen oxide content at idle and rated speed; Make the recorded nitrogen oxide content values ​​into a line graph / curve graph / trend graph / distribution graph; Graphically analyze the changing trends of NOx levels, observing the differences in NOx levels between idling and rated speed, as well as NOx emission results at different emission stages, including the peak values ​​at idling and rated speed. In step 2, the process of obtaining the linear detection data of nitrogen oxide content includes: Start the engine, preheat the engine to an oil temperature of 80°C, and monitor the engine speed throughout the process; Follow the instructions in the APP software that comes with the device. When the APP prompts the loading countdown, press the accelerator pedal to the bottom within 1 second. When the APP prompts the unloading countdown, release the accelerator pedal completely. Repeat the loading and unloading process three times to complete a complete test cycle. The measurement includes linear detection data of nitrogen oxide content during the entire process of engine acceleration from idle speed to rated speed in the unit time of 10 seconds in the loading and holding stage and 10 seconds in the unloading and holding stage, where idle speed is one rotation and rated speed is three rotations.

2. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 1, characterized in that: In step 1, the process of measuring the nitrogen oxide content of the vehicle engine includes: Enter the vehicle information of the vehicle to be tested, including the vehicle model, vehicle identification code, and engine model, so that a dedicated testing route can be automatically assigned. The vehicle to be tested should be parked in a safe area without turning off the engine, and the engine should be in a hot state before testing. Before testing, the exhaust system is pre-treated by blowing through it three times in a free acceleration process to clean any residual pollutants in the exhaust system. After preheating the nitrogen oxide detector, insert the sampling tube of the nitrogen oxide detector into the exhaust pipe of the vehicle or engine. The nitrogen oxide detector is a portable nitrogen oxide detector manufactured using a high-sensitivity automotive nitrogen oxide sensor based on electrochemical principles. Open the APP software that comes with the device and select the vehicle type and inspection standard that is suitable for the vehicle to be inspected Based on the nitrogen oxide detector, the in-situ free acceleration method is used to measure the nitrogen oxide content in automobile engine exhaust emissions.

3. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 1, characterized in that: In step 4, the process of setting the effective monitoring values ​​of the engine exhaust temperature and exhaust wind speed includes: Based on the analysis results of the nitrogen oxide content change trend, the equipment's accompanying APP software automatically identifies invalid measurements, including those that do not meet the engine exhaust temperature and engine exhaust wind speed standards; Analyze the temperature measured by the engine exhaust monitoring, the ratio to the temperature before the engine exhaust pipe and the SCR temperature, and clarify the effective values ​​of the engine exhaust temperature and exhaust wind speed monitoring for the nitrogen oxide content test to ensure that the SCR urea injection system is in normal working condition.

4. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 3, characterized in that: For engine exhaust temperature, the effective value of engine exhaust temperature monitoring is set as follows: when the ambient temperature is ≥15℃, the exhaust temperature is ≥90℃; when the ambient temperature is <15℃, the exhaust temperature is ≥70℃. Test results above this temperature are considered valid. For the engine exhaust wind speed, the effective value of the engine exhaust wind speed monitoring is set to: the wind speed at rated speed ≥ 3 times the wind speed at idle speed, and the test results above this multiple are considered valid.

5. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 1, characterized in that: In step 5, the process of determining violations includes: The AI ​​recognition function built into the APP software analyzes the collected nitrogen oxide content values ​​and automatically determines whether the exhaust emissions exceed the standard; If exhaust emissions do not exceed the standard, the AI ​​automatically determines whether the system has been blocked or tampered with by flashing by analyzing the trend of changes in nitrogen oxide levels. Based on the classification standards for vehicles in the National V and National VI emission stages, effective values ​​are set to determine whether diesel and gas vehicles have falsified pollution control devices or OBD.

6. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 5, characterized in that: For diesel vehicles in the National V emission stage, if the peak nitrogen oxide emissions at idle speed are ≥300ppm and the peak nitrogen oxide emissions at rated speed are ≥600ppm, it is determined to be OBD fraud; For diesel vehicles in the National V emission stage, if the peak nitrogen oxide emissions at idle speed are ≥300ppm and the peak nitrogen oxide emissions at rated speed are ≤600ppm, it is determined that the vehicle pollution control device is falsified; For diesel vehicles in the China VI emission stage, if the peak nitrogen oxide emissions at idle speed are ≥200ppm and the peak nitrogen oxide emissions at rated speed are ≥500ppm, it is determined to be OBD fraud; For gas vehicles in the National VI emission stage, if the peak nitrogen oxide emission is ≥900ppm at the rated speed, it is determined that the pollution control device is falsified.

7. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 1, characterized in that: In step 6, the process of uploading the detection data in real time includes: Integrate vehicle engine inspection records, automatically generate inspection reports, and save the inspection reports in PDF format; Write a data upload program based on the API provided by the cloud platform, read the test data, package it according to the format required by the cloud platform, and upload it to the cloud platform for storage and processing; According to the requirements of the regulatory authorities, the test data is formatted and packaged, and the packaged data is uploaded to the data platform of the ecological environment management department.

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