Rapid detection method for nitric oxide in tail gas emission of vehicle engine

Abstract

The invention discloses a method for rapidly detecting nitrogen oxide in tail gas emission of a vehicle engine, which relates to the technical field of tail gas detection and adopts a free acceleration method to measure the nitrogen oxide content of the vehicle engine. Acquiring nitrogen oxide content linear detection data of the whole process of accelerating the engine from the idle speed to the rated rotating speed in unit time; the nitrogen oxide content value in the whole detection process is recorded, a corresponding graph is made, and the change trend of the nitrogen oxide content is analyzed; based on vehicle types and detection standards built in APP software matched with equipment, effective values of engine tail gas temperature and exhaust air speed monitoring are set. According to the portable nitrogen oxide detector disclosed by the invention, the content of nitrogen oxide discharged by tail gas of an automobile engine is measured by using an in-situ free acceleration method (GB3847-2018 standard appendix A), and the full detection period does not exceed three minutes, so that the detection efficiency is improved, and a law enforcement department can conveniently implement road inspection at an intersection with large traffic flow.

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 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 standard "GB18285-2018 Gasoline Vehicle Pollutant Emission Limits and Measurement Methods (Dual Idle Method and Simple Operating Condition Method)" 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 from 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 from 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. During the inspection, an external 220V power supply, chassis dynamometer, etc. are required. It can only be used by vehicle inspection agencies with fixed sites and is not suitable for random road inspections and home inspections;

[0007] 2. The vehicle inspection agency adopts 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. During the inspection, an external 220V power supply, chassis dynamometer, etc. are required. It can only be used by vehicle inspection agencies with fixed sites and is not suitable for random road inspections and home inspections;

[0008] 3. The "on-board road test method" of the DB11 / 1476-2017 Heavy-duty Vehicle Nitrogen Oxide Rapid Detection Method and Emission Limit" standard is adopted. During the test, installation personnel are required to install the equipment, and the test personnel follow the vehicle. After the test, the equipment is disassembled and transported back to the test starting point. There are many requirements for personnel, and the total test cycle is too long, the efficiency is low, and it is not suitable for random road inspections and home inspections. In addition, the test equipment needs to be loaded on the vehicle and driven with the vehicle for more than 2,000 meters. During the test, the road condition must be stable and there must be no ups and downs. The vehicle must maintain a constant speed and cannot increase or decrease gears or increase or decrease the throttle. In the actual test process, the test site is difficult to determine, and it is not suitable for random road inspections and home inspections.

[0009] 4. Use the "remote sensing method" specified in the standard "HJ845-2017 Measurement Method and Technical Requirements for Exhaust Pollutants from In-use Diesel Vehicles (Remote Sensing Monitoring Method)" issued by the Ministry of Ecology and Environment. The detection equipment needs to be fixed on the side of the road to detect a certain emission value of passing vehicles (point detection). When the 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 issued by the Motor Vehicle Emission Monitoring Center of the Institute of Environmental Sciences, the Asian Clean Air Center, and the School of Environment of Tsinghua University "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 not enough to screen out high-emission vehicles"). It cannot screen out high-emission vehicles, let alone distinguish between falsification of vehicle pollution control devices, shielding of OBD functions, and other behaviors. Summary of the invention

[0011] The present invention aims to provide a method for quickly detecting nitrogen oxides in exhaust emissions from vehicle engines 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 rapid detection method for 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 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, and unit time is 10 seconds for loading and holding stage and 10 seconds for unloading and holding stage;

[0016] Step 3: Record the nitrogen oxide content value during the whole detection process, and make corresponding graphs to analyze the change trend of nitrogen oxide content;

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

[0018] Step 5: Based on the built-in AI recognition function of the device's supporting APP software, it is automatically determined that the vehicle exhaust emissions do not exceed the standard but there are violations, among which the violations include falsification of vehicle pollution control devices, shielding of OBD functions, etc.;

[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’s data platform synchronously 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 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 without turning off the engine. Before testing, make sure the engine is hot and in good mechanical condition.

[0022] Before the test, the exhaust system is pre-treated by blowing the exhaust system through three free acceleration processes or other equivalent methods to clean the residual pollutants in the exhaust system. The exhaust system pre-treatment is 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 the engine, wherein the nitrogen oxide detector is a portable nitrogen oxide detector manufactured by a high-sensitivity vehicle nitrogen oxide sensor based on the electrochemical principle;

[0024] Open the APP software that comes with the device, and select the vehicle type and test standard that are 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 inspections 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”);

[0025] Based on the nitrogen oxide detector, the in-situ free acceleration method (Appendix A in the standard "GB3847-2018 Diesel Vehicle Pollutant Emission Limits and Measurement Methods (Free Acceleration Method and Loaded Deceleration Method)") 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] Combined with the operation standard of GB18285-2018, operate according to the prompts in the equipment 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). When the APP software prompts the unloading countdown, the accelerator pedal needs to be completely released. 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 in the whole 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, wherein the idle speed is one rotation and the 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 change trend of 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 between idle speed and rated speed, as well as the nitrogen oxide emission results in different emission stages are observed. Among them, the nitrogen oxide emission results in 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 value of the engine exhaust temperature and exhaust wind speed monitoring includes:

[0035] Based on the analysis results of the changing trend of nitrogen oxide content, the equipment supporting APP software is used to automatically identify invalid measurements, including engine exhaust temperature not meeting the standard and engine exhaust wind speed not meeting the standard. Exhaust temperature not meeting the standard will result in diesel vehicle urea not being sprayed and urea not being decomposed, gas vehicle three-way catalytic converter not reacting, engine exhaust wind speed not meeting the standard, and the actual emission value at the rated speed cannot be measured;

[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] The 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: the ambient temperature is ≥15°C, the exhaust temperature is ≥90°C; the ambient temperature is <15°C, the exhaust temperature is ≥70°C, and the detection 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 deemed 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 shielding or program tampering by analyzing the trend of nitrogen oxide content changes, including: 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, the 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 the urea solution lower than the national standard requirements is used, and the OBD reduces the urea injection amount, etc., so as to reduce the vehicle's urea consumption and reduce the cost of using the vehicle;

[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] The further improvement of the technical solution of the present invention is that 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;

[0044] 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 that the vehicle pollution control device is falsified;

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

[0046] For gas vehicles in the National VI emission stage, the peak nitrogen oxide emissions at the rated speed are ≥900ppm, which is determined to be a falsification of pollution control devices.

[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 test records, automatically generate test reports, and save the test 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, municipal and municipal ecological environment management departments.

[0051] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with 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 to improve the full-scenario applicability of the device, making it easier for law enforcement departments to implement road inspections and household spot checks.

[0053] 2. The present invention provides a method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions. 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 departments to implement road inspections at intersections with heavy traffic.

[0054] 3. The present invention provides a method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions. The portable nitrogen oxide detector uses a dedicated APP software that is equipped with the equipment and has built-in standards to automatically determine whether the nitrogen oxides in the engine exhaust emissions exceed the standard. It also has a built-in AI recognition function that automatically determines whether the vehicle exhaust emissions do not exceed the standard, but there are acts 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 drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0056] Figure 1 It is a 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 picture of the pollution control device for National Five diesel vehicles of the present invention (the temperature sensor before the pad is raised);

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

[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 the pollution of the National VI diesel vehicle of the present invention (the effective injection amount of urea is low);

[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 graph of nitrogen oxide emissions from National VI natural gas vehicles that exceed the emission standards of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Embodiment 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 without shutting down the engine. Before testing, make the engine hot and in good mechanical condition. Before testing, use three free acceleration processes or other equivalent methods to blow the exhaust system to pre-treat the exhaust system to clean the residual pollutants in the exhaust system. The exhaust system pre-treatment 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 supporting the equipment, and select the vehicle type and detection standard applicable to the vehicle to be tested (such as road inspection of diesel vehicles in the National VI emission stage, select "Vehicle Type: National VI Diesel Vehicle", "Detection Standard: Rapid Detection Method"; household inspection of non-road mobile machinery in the National III emission stage, select "Vehicle Type: National III Non-road Mobile Machinery", "Detection Standard: Free Acceleration Method"). Among them, the software name is: Hangzhou Yuyang Environmental Protection, APP filing number: Zhejiang ICP filing number 2024089450, main functions: collect data from the nitrogen oxide detector, make automatic judgments, automatically generate reports and upload them to the cloud platform, based on the nitrogen oxide detector, use the in-situ free acceleration method (Appendix A 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 of automobile engine exhaust emissions;

[0067] Step 2: Obtain the linear detection data of the nitrogen oxide content of the whole process of the engine accelerating from idle speed to rated speed within a unit time, wherein the idle speed is one rotation, the rated speed is three rotations, the unit time is 10 seconds for the loading and holding stage, and 10 seconds for the unloading and holding stage. Start the engine, preheat the engine to an oil temperature of 80°C, and monitor the engine speed throughout the process. Combined with the operation standard of GB18285-2018, operate according to the prompts in the equipment supporting APP software. According to the loading countdown prompted by the APP software, the accelerator pedal is stepped on 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 the nitrogen oxide content of the whole process of the engine accelerating from idle speed to rated speed within a unit time of 10 seconds for the loading and holding stage and 10 seconds for the unloading and holding stage, wherein the idle speed is one rotation, and the rated speed is three rotations;

[0068] Step 3. Record the nitrogen oxide content values ​​during the entire detection process and make corresponding graphs to analyze the changing trend of the nitrogen oxide content. Analyze the nitrogen oxide values ​​of the engine emissions recorded by the APP software, including the nitrogen oxide content at idle and rated speeds. Make the recorded nitrogen oxide content values ​​into line graphs / curve graphs / trend graphs / distribution graphs and other graphs, analyze the changing trend of the nitrogen oxide content through graphs, observe the difference in nitrogen oxide content at idle and rated speeds, and the nitrogen oxide emission results at different emission stages, where the nitrogen oxide emission results at different emission stages include the peak value at idle and rated speeds;

[0069] Step 4. Based on the vehicle type and detection standard built into the equipment supporting APP software, set the effective value 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 not meeting the standard and engine exhaust wind speed not meeting the standard. Exhaust failure will result in diesel vehicle urea not being sprayed, urea not being decomposed, gas vehicle three-way catalytic converter not reacting, engine exhaust wind speed not meeting the standard, and the actual emission value at rated speed cannot be measured (see patent: Patent No. ZL202221773947.2 for details). Analyze the temperature measured by 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 engine exhaust temperature and exhaust wind speed monitoring for nitrogen oxide content test to ensure that the SCR urea injection system is in normal working condition.

[0070] Furthermore, 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;

[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 the test results above this multiple are deemed valid;

[0072] Step 5. Based on the built-in AI recognition function of the equipment supporting APP software, it is automatically determined that the automobile exhaust emissions do not exceed the standard but there are violations. Among them, the violations include falsification of vehicle pollution control devices, shielding 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 nitrogen oxide content changes, AI automatically determines whether there is any shielding or rewriting tampering with the program, including: whether the front temperature sensor is raised to make the vehicle idle Whether to remove the front and rear nitrogen oxide sensors of the SCR system, use a nitrogen oxide simulator, turn off the OBD torque limit function, so that the vehicle does not spray urea; whether to remove or turn off the urea injection pump and urea level sensor of the SCR system, turn off the OBD torque limit function, so that the vehicle does not spray urea; whether to use urea solution lower than the national standard requirements, reduce the urea injection amount by OBD, etc., 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 fraudulent pollution control devices and OBD fraud;

[0073] Furthermore, for diesel vehicles in the National V emission stage, if the NOx emission peak value at idle speed is ≥300ppm and the NOx 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 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 that the vehicle pollution control device is falsified;

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

[0076] For gas vehicles in the National VI emission stage, if the nitrogen oxide emission peak is ≥900ppm at the rated speed, it is determined that the pollution control device is fake;

[0077] Step 6. Generate PDF files in real time based on the test records for archiving, upload the test data to the cloud platform and the regulatory department data platform synchronously in real time, integrate the vehicle engine test records, automatically generate a test report, and save the test report in PDF format. Write a data upload program based on the API provided by the cloud platform, read the test data, package it in 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 test 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, prefectural and municipal ecological environment management departments.

[0078] Embodiment 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 emission of nitrogen oxides from a compression ignition engine (most vehicles use diesel fuel, and a small amount of vehicles use methanol fuel) (hereinafter taking diesel fuel as an example):

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

[0080] ⑴ Combustion process: When burning in the engine, the 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 Generation of nitrogen oxides (NOx): During the combustion process, nitrogen and oxygen react chemically to generate 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] ⑶ Nitrogen oxide emissions: Incomplete combustion in the engine combustion process and nitrogen oxidation reaction under high temperature and high pressure conditions generate excessive nitrogen oxides, which are discharged into the atmosphere, forming nitrogen oxide pollution in automobile exhaust;

[0083] Furthermore, the general technical principle of reducing nitrogen oxide emissions from compression ignition engine exhaust is briefly described as follows:

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

[0085] ⑴ The front temperature sensor of the diesel engine exhaust pipe detects that the temperature reaches 200°C, and the urea pump starts to spray urea;

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

[0087] ⑶In the SCR carrier, ammonia reacts with nitrogen oxides to generate nitrogen and water;

[0088] ⑷The operating temperature of SCR catalytic reduction is 250-450℃, and the optimal operating temperature is 350℃;

[0089] ⑸When the sensors of the SCR urea injection system detect an abnormality, the vehicle will be torque-limited, which will significantly reduce 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°C and starts to inject urea; the temperature inside the SCR carrier reaches 250°C and starts catalytic reduction;

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

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

[0093] ⑵Remove 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] ⑶ Remove or turn off the urea injection pump and urea level sensor of the SCR system, turn off the OBD torque limit function, and prevent the vehicle from injecting urea;

[0095] (4) Use urea solution lower than the national standard, reduce the urea injection amount through OBD, etc., so as to reduce the vehicle urea consumption and reduce the vehicle cost;

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

[0097] ⑴Verification of diesel engine exhaust temperature monitoring: It is necessary to verify the temperature measured by the engine exhaust monitoring, the ratio of the temperature before the engine exhaust pipe and the SCR temperature, and ensure that the SCR is working normally above a certain temperature measured by the exhaust monitoring;

[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 are shown in the following table (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℃, and 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 in 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 following table (unit × 10 -6 or ppm):

[0108]

[0109]

[0110] Note: The classification standards for vehicles in the National V and National VI emission stages shall be 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 fraudulent OBD is set as:

[0112] For diesel vehicles in the National V emission stage, the nitrogen oxide emission peak value at idle speed is ≥300ppm, and the nitrogen oxide emission peak value at rated speed is ≥600ppm, which is confirmed as OBD fraud;

[0113] The peak nitrogen oxide emission of diesel vehicles in the National V emission stage at idle speed is ≥300ppm, and the peak nitrogen oxide emission at rated speed is ≤600ppm, which is confirmed to be a fraud in vehicle pollution control devices;

[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 fraud.

[0115] Embodiment 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 emission of nitrogen oxides (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 fuel 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 emission from gas engine exhaust is the same as that of diesel engine. Since the temperature in the engine cylinder of a gas engine is higher than that of a diesel vehicle during normal operation, the total amount of nitrogen oxide emitted by a gas engine is much higher than that of a diesel engine under the same displacement.

[0118] Furthermore, the technical principle of reducing nitrogen oxide emissions from gas vehicle engine exhaust is 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] ⑵ Redox reaction: At high temperature, platinum-palladium catalyzes CO to be oxidized into CO2, HC compounds to be oxidized into water and carbon dioxide, and rhodium catalyzes NOx to be reduced into nitrogen;

[0121] For vehicles at the National V emission stage and below (such as the National IV gasoline-to-gas conversion), the exhaust after-treatment device is only coated with platinum and palladium precious metals, and no rhodium precious metal coating. Therefore, the nitrogen oxide emissions at the National V emission stage and below are not reduced, so the nitrogen oxide emissions are very high;

[0122] Vehicles in the National VI emission stage have platinum, palladium and rhodium precious metal coatings in the exhaust after-treatment device, so nitrogen oxide emissions are greatly reduced;

[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 working 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 the falsification of exhaust pollution control devices for gas vehicles (currently gas vehicles OBD do not have exhaust monitoring function) is to remove or replace unqualified three-way catalytic converters for vehicles in the National VI emission stage 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 National VI emission stage gas vehicles were tested. The results of the test nitrogen oxide emissions are shown in the following table (unit × 10 -6 or ppm):

[0133]

[0134]

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

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

[0137] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A rapid detection method for nitrogen oxides in vehicle engine exhaust emissions, 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 unit time; Step 3: Record the nitrogen oxide content value during the whole detection process, and make corresponding graphs to analyze the change trend of nitrogen oxide content; Step 4: Based on the vehicle type and detection standard built into the device's APP software, set the effective values ​​for monitoring engine exhaust temperature and exhaust wind speed; Step 5: Based on the built-in AI recognition function of the device's supporting APP software, it is automatically determined that the vehicle exhaust emissions do not exceed the standard but there are violations, among which the violations include falsification of vehicle pollution control devices and shielding of OBD functions; 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’s data platform synchronously in real time.

2. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 1, characterized in that: In the 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 as to automatically assign a dedicated testing line. Park the vehicle to be tested in a safe area without turning off the engine, and keep the engine in a hot state before testing. Before testing, the exhaust system is pre-treated by blowing the exhaust system through three free acceleration processes to clean the 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 the engine, wherein the nitrogen oxide detector is a portable nitrogen oxide detector manufactured by a high-sensitivity vehicle nitrogen oxide sensor based on the electrochemical principle; Open the APP software that comes with the device and select the vehicle type and test standard that is suitable for the vehicle to be tested 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 2, characterized in that: In the 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 supporting the equipment to operate. According to the loading countdown prompted by the APP software, press the accelerator pedal to the bottom within 1 second. When the APP software prompts the unloading countdown, the accelerator pedal needs to be completely released. Repeat the loading and unloading process three times to form a complete detection cycle; The measurement includes linear detection data of nitrogen oxide content in the whole 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, wherein the idle speed is one rotation and the rated speed is three rotations.

4. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 1, characterized in that: 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; By graphically analyzing the changing trend of nitrogen oxide content, the difference in nitrogen oxide content between idle speed and rated speed, as well as the nitrogen oxide emission results in different emission stages are observed. Among them, the nitrogen oxide emission results in different emission stages include the peak value at idle speed and the peak value at rated speed.

5. 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 changing trend of nitrogen oxide content, the equipment supporting APP software is used to automatically identify invalid measurements, including engine exhaust temperature and engine exhaust wind speed that do not meet the 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.

6. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 5, 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℃. The 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 deemed valid.

7. 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 the exhaust emissions do not exceed the standard, the AI ​​will automatically determine whether the program has been blocked or tampered with by analyzing the trend of changes in nitrogen oxide content; 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.

8. The method for rapid detection of nitrogen oxides in vehicle engine exhaust emissions according to claim 7, characterized in that: 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; 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 that the vehicle pollution control device is falsified; For diesel vehicles in the National VI emission stage, if the nitrogen oxide emission peak value at idle speed is ≥200ppm, and the nitrogen oxide emission peak value at rated speed is ≥500ppm, it is determined to be OBD fraud; For gas vehicles in the National VI emission stage, the peak nitrogen oxide emissions at the rated speed are ≥900ppm, which is determined to be a falsification of pollution control devices.

9. 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 test records, automatically generate test reports, and save the test 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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