CN114991922B - Real-time early warning method for exceeding of NOx emission of vehicle - Google Patents

Abstract

The invention relates to the technical field of vehicle emission early warning, and discloses a real-time early warning method for exceeding the standard of vehicle NOx emission, which comprises the following steps: step 1: collecting vehicle data as a vehicle running data set; step 2: dividing a vehicle driving data set to obtain a vehicle driving fragment; step 3: processing the vehicle driving segment to obtain an effective vehicle driving segment; step 4: dividing the effective vehicle driving fragments according to the fragment dividing conditions to obtain a driving fragment group; step 5: according to a standard working condition construction strategy, selecting effective vehicle driving fragments from the driving fragment groups, and constructing actual emission test working conditions of the vehicle; step 6: calculating the NOx emission level of the vehicle according to the actual emission test working condition of the vehicle; step 7: and when the NOx emission level of the vehicle does not meet the requirement, carrying out real-time early warning according to an early warning strategy. The invention can timely and accurately judge whether the NOx emission exceeds the standard and perform early warning in the actual use process of the vehicle, and is beneficial to scientific monitoring and treatment of the NOx emission of the vehicle.

Description

A real-time early warning method for excessive vehicle NOx emissions

Technical field

The invention relates to the technical field of vehicle emission early warning, and specifically relates to a real-time early warning method for vehicle NOx emission exceeding the standard.

Background technique

With the promotion and realization of the concept of sustainable economic and social development and circular economy, my country's energy conservation and emission reduction work has achieved remarkable results in recent years. The environmental conditions of many cities that were originally heavily polluted have been greatly improved. The overall urban environment The trend is good. However, the urban air pollution situation is still not optimistic. Analyzing various indicators of urban air pollution, we can find that there is an obvious phenomenon of pollution value growth - while the total amount of SO ₂ pollution in the atmosphere has decreased, the total amount of NOx pollution has increased. Showing an upward trend. The reason is that the number of motor vehicles in cities is currently growing rapidly, and the corresponding exhaust gas emissions have also increased accordingly. According to statistics, the NOx emissions from motor vehicles currently account for 32% of the national statistics, and among them NOx emissions from heavy-duty vehicles account for 80% of all vehicle NOx emissions.

In order to effectively curb vehicle pollutant emissions and improve air pollution, the country has promulgated corresponding vehicle pollutant emission standards in order to achieve environmental protection through product technology upgrades. In addition, the newly implemented emission control regulations on pollutant emission limits and measurement methods for heavy-duty diesel vehicles (China Phase 6) also clearly require that vehicles must be equipped with on-board terminals to collect relevant data and send it to designated platforms for NOx emission monitoring. However, relevant standards and literature do not specify how to determine and provide early warning for vehicle NOx emissions exceeding the standard, and have not achieved the purpose of scientific monitoring and management of vehicle NOx emissions.

In addition, a large number of experimental studies have found that there is a large difference between the actual emissions of heavy-duty vehicles and the measurement results when the regulations were announced. The reasons include: there are differences between the standard test conditions required by regulations and the actual road conditions of the vehicles; Road working conditions are often fragmented and scattered, and do not constitute complete working conditions. They cannot correspond to the working conditions fixed by regulations, making it difficult to apply standards. The data collected by vehicle-mounted terminals cannot be effective, and NOx emission supervision exists. difficulty.

Contents of the invention

The present invention is intended to provide a real-time early warning method for vehicle NOx emission exceeding the standard, which can accurately determine whether the NOx emission exceeds the standard during actual use of the vehicle, and is helpful for the scientific monitoring and management of vehicle NOx emission.

The basic solution provided by the present invention is: a real-time early warning method for vehicle NOx emission exceeding the standard, which includes the following steps:

Step 1: Collect vehicle data as a vehicle driving data set;

Step 2: Divide the vehicle driving data set to obtain vehicle driving segments; when dividing, use a refueling cycle as the segmentation point for large segments; use the vehicle speed equal to 0 as the segmentation point for small segments;

Step 3: Process the vehicle driving segments according to the filtering processing conditions to obtain effective vehicle driving segments;

Step 4: Divide the effective vehicle driving segments according to the segment division conditions to obtain the driving segment group;

Step 5: Establish a strategy according to standard working conditions, select valid vehicle driving segments from the driving segment group, and construct actual vehicle emission test conditions;

Step 6: Calculate the vehicle NOx emission level based on the vehicle’s actual emission test conditions;

Step 7: When the NOx emission level of the vehicle does not meet the requirements, a real-time warning is carried out according to the warning strategy.

The working principle and advantage of the present invention are that: vehicle data is collected to obtain vehicle driving segments, and the vehicle driving segments are appropriately screened to obtain reliable and effective effective vehicle driving segments, and then the effective vehicle driving segments are further classified. The relatively fragmented and dispersed effective vehicle driving segments are organized into complete actual vehicle emission test conditions according to the standard working condition construction strategy. In this way, this program can reorganize the fragmented data fragments into a comprehensive actual vehicle emission test condition. The conditions can be compared with the standard test conditions in the standard regulations, so that the existing standards can be adapted to the actual vehicle operating scenarios, and then the vehicle NOx emission level can be calculated and approved based on this working condition. The data basis meets the standards and is valid, and then It can accurately determine whether the NOx emissions during actual use of the vehicle exceed the standard, which is helpful for the scientific monitoring and management of vehicle NOx emissions.

More importantly, when dividing the vehicle driving data set, this solution specifically selects the refueling cycle as the segmentation point for large segments, and divides the vehicle data into vehicle driving segments with special time characteristics. Existing vehicle emission calculation methods often do not divide such time-based vehicle driving segments, but simply follow the newly implemented emission control regulations of heavy-duty diesel vehicle pollutant emission limits and measurement methods (China Phase 6) The fragment division method given in is divided based on vehicle speed. Although this type of classification method meets the standard requirements, it is less detailed and achieves only fragmentary distinctions, which cannot provide more effective information for NOx emission supervision and control.

This solution uses the above-mentioned special time division of vehicle driving segments. While distinguishing vehicle driving segments, the factors that will further affect vehicle NOx emissions - oil products are also taken into consideration. This program discovered an important factor that has an impact on vehicle NOx emission values that has been ignored in the current vehicle NOx supervision and governance - oil product, that is, the quality of the fuel used in the vehicle. Factors that are conventionally considered to have an impact on vehicle NOx emissions are often vehicle operating conditions that lead to substandard conditions or vehicle SCR (engine exhaust gas treatment urea system) failure. In fact, the fuel used by the vehicle will also affect NOx emissions. Poor quality fuel will increase emissions, but this is often overlooked, making the impact of oil quality an invisible error factor that leads to inaccurate identification of some causes of excessive emissions, resulting in the failure to effectively control the problem of excessive emissions.

This plan has made a breakthrough in discovering this point, and accordingly uses the refueling cycle as a large segmentation point to divide vehicle driving segments, and uses the refueling cycle to distinguish oil products, which naturally incorporates oil products into the NOx emission evaluation basis. The data within a single refueling cycle naturally eliminates the impact of different oil products on emissions, making it easier to accurately identify the reasons for excessive emissions within a single refueling cycle. At the same time, by comparing the emissions in different refueling cycles, the oil products can be reclassified. Factors will be taken into account as the reasons for exceeding emission standards. This scheme is set up in this way, which can help to more accurately confirm the reasons for excessive vehicle NOx emissions from more dimensions, thereby assisting in the scientific monitoring and effective and precise management of vehicle NOx emissions.

Further, in step 2, the refueling period is the driving period between two adjacent refueling behaviors of the vehicle.

The refueling cycle is determined based on the refueling behavior, and the differentiation method is simple and effective. Moreover, by using refueling behavior as a distinction, when dividing refueling cycles, the oil products refueled at different stages of the vehicle can be included in the classification basis of vehicle driving segments, providing a reference for oil type evaluation for subsequent analysis of the reasons for excessive vehicle emissions.

Further, in step 3, the filtering processing conditions include deleting unqualified data from the vehicle driving segments; wherein the unqualified data is data that does not meet the data qualification conditions;

The qualifying conditions for the data are:

266K≤t ₁ ≤T, T＝-0.4514×(101.3-P _b )+311;

h≤2400m;

t ₂ ≥70℃;

Among them, t ₁ is the ambient temperature of the vehicle, in K; T is the standard ambient temperature, in K; P _b is the atmospheric pressure value; h is the altitude of the vehicle; t ₂ is the vehicle engine coolant temperature.

The data qualification conditions are set in accordance with the national pollutant emission standards, specifically the "Heavy-duty Diesel Vehicle Pollutant Emission Limits and Measurement Methods (China Phase Six)" standard. Such settings can ensure that the effective vehicle driving segments obtained by screening are processed. The data are all in line with national standards, thus ensuring high reliability of early warning.

Further, the filtering processing conditions also include that if unqualified data continuously appears in a certain vehicle's driving segment, and the number of consecutive unqualified data points exceeds 4% to 6% of the total amount of the vehicle's driving segment data, then the vehicle's driving segment data will be deleted. .

The vehicle driving segments with a large amount of continuous unqualified data are deleted, which effectively prevents the vehicle driving segments with more errors from affecting the overall vehicle driving segment data, and the data reliability is higher.

Furthermore, the filtering processing conditions also include: if the number of unqualified data points in a certain vehicle driving segment exceeds 20% of the total amount of data in the vehicle driving segment, delete the vehicle driving segment data.

Vehicle driving segments with a large amount of unqualified data are deleted to strictly eliminate the negative impact of unqualified data on the overall vehicle driving segment data, and the data reliability is higher.

Further, in step 4, the segment division condition is to divide according to the vehicle type and standard regulations; the obtained driving segment group includes an urban driving segment group, a suburban driving segment group and a high-speed driving segment group.

With this setting, the fragmented vehicle driving segments are classified, and the segment division meets the requirements of standard regulations, making it easier to subsequently establish actual vehicle emission test conditions.

Further, in step 5, the standard working condition construction strategy is to build according to the vehicle type and standard regulations; when forming, extract effective vehicle driving segments from the urban driving segment group, suburban driving segment group and high-speed driving segment group, and Set up in proportion to form the actual emission test conditions of the vehicle.

Reintegrate the effective vehicle driving segments in the scattered different types of driving segment groups according to a certain proportion into actual vehicle emission test conditions that meet the requirements of standard regulations and can be effectively determined. That is, this solution can also use scattered segments. It forms a complete working condition, because during the actual operation of the vehicle, the operating speed of its operating road section is variable, and the composed driving segments are also scattered, and will not operate in accordance with standard regulations. This plan is set up in this way, which is consistent with the actual vehicle operation conditions. Adaptable and practical.

Further, in step 5, when selecting valid vehicle driving segments from the driving segment group, first select valid vehicle driving segments from a refueling cycle; if the valid vehicle driving segments provided in a refueling cycle are not enough to form a complete vehicle actual Emission test conditions, then obtain the valid vehicle driving segments from the previous refueling cycle to form a complete vehicle actual emission test condition. If this refueling cycle is the first refueling cycle of the vehicle, then obtain the valid vehicle driving segments from the refueling cycle. Valid vehicle driving segments are obtained in the last refueling cycle to form a complete vehicle actual emission test condition.

This setting ensures that the amount of data obtained in the actual vehicle emission test conditions is sufficient and complete, and can provide sufficient data analysis basis for emission warning.

Further, in step 6, when calculating the vehicle NOx emission level, the sliding window method is used.

The sliding window method, also known as the ruler method, is often used to solve the problem of finding the properties (length, etc.) of continuous intervals that meet certain conditions. It can effectively reduce repeated calculations and reduce time complexity. The sliding window method is used here to confirm the NOx emission level, which can quickly process the data in the vehicle's actual emission test conditions according to certain conditions and quickly confirm the vehicle's NOx emission level.

Further, in step 7, the early warning strategy includes: within a preset number of refueling cycles, if the vehicle emission level exceeds the standard for more than or equal to 2 consecutive times or the total number of vehicle emission levels exceeds the standard for more than or equal to 3 times, then perform an early warning. .

In this setting, a certain early warning scale is set, and early warning is carried out according to the early warning scale, and the early warning is more detailed.

Description of the drawings

Figure 1 is a schematic flowchart of a whole-day method according to Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 2 is a schematic diagram of the refueling cycle segmentation of the vehicle driving segment according to Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 3 is a schematic diagram of a vehicle driving segment segmented into small segments according to Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 4 is an example diagram of non-standard data in Step 3 of Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 5 is an example diagram of the screening process in Step 3 of Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 6 is an example diagram of the vehicle's actual emission test conditions established in Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 7 is an example diagram of window division based on accumulated work in Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 8 is an example diagram of changes in accumulated emission quality of NOx according to Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 9 is a schematic diagram of the window pass rate of an example vehicle in 10 refueling cycles according to Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention;

Figure 10 is a schematic diagram of the real-time early warning mechanism of Embodiment 1 of a real-time early warning method for excessive vehicle NOx emissions according to the present invention.

Detailed ways

The following is a further detailed description through specific implementation methods:

Example 1:

The embodiment is basically as shown in Figure 1:

A real-time early warning method for vehicle NOx emission exceeding the standard, which is characterized by including the following steps:

Step 1: Collect vehicle data as a vehicle driving data set.

Specifically, the vehicle-mounted terminal on the vehicle is used to collect vehicle data. The vehicle data collected includes vehicle speed, engine speed, engine net output torque, engine coolant temperature, fuel tank level, altitude, longitude and latitude, NOx output value, etc. Detailed data As shown in Appendix 1.

Schedule 1

serial number Collection items unit 1 speed km/h 2 Atmospheric pressure kPa 3 Engine net output torque % 4 friction torque % 5 Engine speed rpm 6 engine fuel flow L/h 7 SCR upstream NOx output value ppm 8 SCR downstream NOx output value ppm 9 Reactant balance % 10 Air intake kg/h 11 SCR inlet temperature ℃ 12 SCR outlet temperature ℃ 13 DPF differential pressure kPa 14 engine coolant temperature ℃ 15 Tank level % 16 longitude ℃ 17 latitude ℃ 18 Accumulated mileage km 19 vehicle cycle work kW

Step 2: Divide the vehicle driving data set to obtain vehicle driving segments; when dividing, use a refueling cycle as the segmentation point for large segments; use the vehicle speed equal to 0 as the segmentation point for small segments. The refueling cycle is the driving cycle between two adjacent refueling actions of the vehicle, as shown in Figure 2.

Specifically, the method for determining the refueling behavior is: first, extract the driving data segments with changes in the fuel tank level value from the vehicle driving data set. If the vehicle is stopped before and after the vehicle stops (the vehicle speed is equal to 0 time point), the vehicle fuel tank level change amount If it exceeds 30%, it will be determined that the liquid level value in the fuel tank corresponds to a refueling behavior. It is convenient and effective to use the fuel tank level to determine the refueling behavior, and can quickly and accurately confirm the refueling cycle.

Specifically, for the vehicle data within a refueling cycle, the vehicle speed equal to 0 is used as the small segment segmentation point, the large vehicle driving segments are segmented with the refueling cycle as the segmentation point, and several small vehicle driving segments are segmented. , the data division is more detailed. After the vehicle driving segments are divided, the average vehicle speed of each small vehicle driving segment is calculated, and the maximum vehicle speed, ambient temperature, altitude, engine water temperature and other information in each small vehicle driving segment are extracted at the same time, so as to facilitate the step Perform data screening processing in 3, as shown in Figure 3. Among them, the ambient temperature described here is defined as: the engine coolant temperature when the vehicle is restarted after being stopped for 6 hours is used as the ambient temperature.

Step 3: Process the vehicle driving segments according to the filtering processing conditions to obtain effective vehicle driving segments.

The filtering processing conditions include deleting unqualified data from the vehicle driving segments; wherein the unqualified data is data that does not meet the data qualification conditions;

The qualifying conditions for the data are:

266K≤t ₁ ≤T, T＝-0.4514×(101.3-P _b )+311;

h≤2400m;

t ₂ ≥70℃;

Among them, t ₁ is the ambient temperature of the vehicle, in K; T is the standard ambient temperature, in K; P _b is the atmospheric pressure value; h is the altitude of the vehicle; t ₂ is the vehicle engine coolant temperature.

As shown in Figure 4, for vehicles in the cold start stage, the data in this stage does not meet the standard of t ₂ ≥ 70°C and should be regarded as unqualified data and deleted.

The filtering processing conditions also include that if unqualified data continuously appears in a certain vehicle's driving segment, and the number of consecutive unqualified data points exceeds 4% to 6% of the total amount of the vehicle's driving segment data, then the vehicle's driving segment data will be deleted; this In the embodiment, if the number of consecutive unqualified data points exceeds 5% of the total amount of the vehicle's driving segment data, the vehicle's driving segment data will be deleted. If the number of unqualified data points in a vehicle's driving segment exceeds 20% of the total data of the vehicle's driving segment, the vehicle's driving segment data will be deleted. As shown in Figure 5, the entire vehicle driving segment that does not meet the above conditions is deleted.

Step 4: Divide the effective vehicle driving segments according to segment division conditions to obtain the driving segment group.

The segment division condition is to divide according to the vehicle type and standard regulations; the obtained driving segment group includes an urban driving segment group, a suburban driving segment group and a high-speed driving segment group. In this example, the selected vehicle model is an N1 heavy-duty vehicle, and the standard and regulatory requirements are the "GB 17691-2018 Heavy-duty Diesel Vehicle Pollutant Emission Limits and Measurement Methods (China Phase Six)" standard;

Specifically, valid vehicle driving segments with a maximum speed less than 55km/h and an average speed between 15-30km/h are divided into urban driving segment groups; valid vehicle driving segments with a maximum speed less than 75km/h and an average speed between 45-70km/h are divided into urban driving segment groups. Driving segments are divided into suburban driving segment groups; driving segments with a maximum vehicle speed greater than 75km/h and an average vehicle speed greater than 70km/h are divided into high-speed driving segment groups.

Step 5: Establish a strategy based on standard working conditions, select valid vehicle driving segments from the driving segment group, and construct actual vehicle emission test conditions.

The standard working condition construction strategy is to build according to the vehicle type and standard regulations; when building, extract effective vehicle driving segments from the urban driving segment group, suburban driving segment group and high-speed driving segment group, and construct the actual emissions of the vehicle in proportion Test conditions.

Specifically, the standard and regulatory requirements followed here are still the "GB 17691-2018 Heavy-duty Diesel Vehicle Pollutant Emission Limits and Measurement Methods (China Phase Six)" standard and regulatory requirements. When the actual vehicle emission test conditions are established, the above The proportional construction is to build according to the proportion of each type of fragment running time, and select different proportion values according to different car models, as shown in Appendix Table 2. Since the vehicle model selected in this embodiment is an N1 heavy-duty vehicle, as shown in Figure 6, its specific driving segments are composed of:

Urban driving segment group: Suburban driving segment group: High-speed driving segment group = 34%: 33%: 33%.

Schedule 2

Moreover, when selecting valid vehicle driving segments from the driving segment group, first select valid vehicle driving segments from a refueling cycle; if the valid vehicle driving segments provided in a refueling cycle are not enough to form a complete vehicle actual emission test condition, Then obtain the valid vehicle driving segments from the previous refueling cycle of the refueling cycle to form a complete vehicle actual emission test condition. If the refueling cycle is the first refueling cycle of the vehicle, then obtain the valid vehicle driving segments from the subsequent refueling cycle. Obtain valid vehicle driving segments during the refueling cycle to form a complete vehicle actual emission test condition. The complete actual vehicle emission test conditions here refer to the actual vehicle emission test conditions that include urban driving segment groups, suburban driving segment groups and high-speed driving segment groups, and the proportions meet the standards.

If valid vehicle driving segments that are sufficient to form a complete vehicle actual emission test condition cannot be obtained from the previous refueling cycle or the next refueling cycle, continue to select the first two or last two refueling cycles to obtain the missing valid vehicle driving segments. , until a complete actual vehicle emission test condition that meets the requirements of standard regulations is constructed.

Step 6: Calculate the vehicle NOx emission level based on the actual vehicle emission test conditions.

When calculating vehicle NOx emission levels, the sliding window method is used.

Specifically, information such as vehicle speed, engine speed, engine net output torque, and NOx output value are extracted from the actual vehicle emission test conditions, and the vehicle emission level is calculated with reference to the emission calculation methods in standard regulations. The emission calculation method in the said standards and regulations refers to the emission calculation method of PEMS test in Appendix K of "GB 17691-2018 Heavy-duty Diesel Vehicle Pollutant Emission Limits and Measurement Methods (China Phase Six)".

For ease of understanding, in this embodiment, an N1 vehicle with a vehicle cycle work of 14.5kWh, an engine maximum power of 135kW, and an engine reference torque of 1000Nm is selected as an example to calculate the vehicle NOx emission level. The engine maximum power and engine baseline torque data are used to determine the cumulative work of the built working conditions; the vehicle cycle work data are used to determine the window division.

Specifically, it includes the following calculation sub-steps:

S1: Determine the window and effective window;

First, the vehicle engine operating power is calculated through the vehicle speed, engine reference torque and actual engine torque. The calculation formula is as follows:

Among them, T _e is the actual engine torque; T _s is the engine reference torque; σ is the engine torque percentage; P is the vehicle engine operating power.

Second, based on the vehicle engine operating power, calculate the cumulative work of the vehicle during the operation process t ₁ , _i to t ₂ , _i time, the calculation formula is as follows:

By calculating the cumulative work of the actual vehicle emission test conditions constructed, the cumulative work curve can be obtained; then, based on the cumulative work curve and engine cycle work, the window is divided from back to front with Δt as the dividing interval to complete the determination of the window . Moreover, each window division must meet the following conditions, as shown in Figure 7:

W _(t2-Δt,i) -W _(t1,i) <W _ref ≤W _(t2,i) -W _(t1,i)

Among them, W _ref is the WHTC cycle work, the unit is kwh; W _(t2,i) is the cumulative work done by the vehicle from the beginning (initial time) to t ₂ time, the unit is kwh; W _(t1,i) is the vehicle from the beginning to the The accumulated work done at time t ₁ , unit kwh; W _(t2-Δt,i) is the accumulated work done by the vehicle from the beginning to time t ₂ -Δt, unit kwh; Δt is the data sampling period, and Δt≤1s.

Third, determine the effective window.

Based on all the windows obtained in the second step, calculate the average power of each window; among them, the window with the average power of the window greater than 20% of the maximum power of the engine is determined as a valid window; in this embodiment, the number of valid windows is recorded as M.

S2: Calculate NOx window specific emissions.

The mass accumulation change curve of NOx is calculated based on the NOx mass concentration (ppm) output by the downstream SCR sensor and the exhaust mass flow rate (g/s). Among them, the exhaust mass concentration is calculated based on the fuel flow rate and intake air volume, and the calculation formula is as follows:

Exhaust mass flow = fuel flow + intake air volume, specifically:

The calculation formula of NOx mass concentration is as follows:

q _{nox_flow} =0.001587×C _{nox_conc} ×q _total

Among them, C _{nox_conc} is the output concentration of the downstream NOx sensor (ppm); q _total is the exhaust mass flow; q _{nox_flow} is the NOx mass concentration.

Further, the cumulative emission mass m of NOx is obtained based on the NOx mass concentration, as shown in Figure 8, and its calculation formula is:

m=∫q _{nox_flow} dt

Furthermore, based on the obtained cumulative emission mass m of NOx and combined with the window interval, the NOx window specific emission is obtained, and its calculation formula is:

Among them, e _i is the specific emission of the i-th window, in mg/(kw*h); m _i is the emission mass of NOx in the i-th window (mg).

S3: Determine the NOx window emission pass rate. The NOx window emission pass rate represents the vehicle NOx emission level.

Specifically, the window specific emission value of each window is obtained according to the method in S2, and the specific emission value of each window is compared with the standard specific emission value; the standard specific emission value is determined according to the requirements of standards and regulations, specifically 690mg/(kw *h).

When the window specific emission value of a window is less than the standard specific emission value, it is determined to be a qualified emission window; here, the total number of all qualified emission windows is recorded as N.

Then the NOx window emission pass rate φ (%) of the PEMS operating condition constructed for the N1 type vehicle in this embodiment is defined as:

In this example, the window pass rate corresponding to the first 10 refueling cycles is shown in Appendix Table 3 and Figure 9;

Schedule 3

Refueling cycle Total number of windows Number of qualifying emission windows Window pass rate % 1 6175 5496 89 2 7256 6893 95 3 6553 6029 92 4 7123 5627 79 5 7652 7116 93 6 6152 1476 twenty four 7 6286 1069 17 8 7562 1286 17 9 7436 1413 19 10 6785 1493 twenty two

Step 7: When the NOx emission level of the vehicle does not meet the requirements, a real-time warning is carried out according to the warning strategy.

The early warning strategy includes: within a preset number of refueling cycles, if the vehicle emission level exceeds the standard for more than or equal to two consecutive times, an early warning will be issued. The above-mentioned emission level exceeding the standard specifically refers to: the NOx window emission pass rate of a certain refueling cycle is less than 90%.

In this embodiment, as shown in Figure 10:

If there is no emission exceeding the standard within the first 10 refueling cycles of the vehicle, it will indicate that there is no risk of emission exceeding the standard;

If within the first 10 refueling cycles of the vehicle, the vehicle’s emission level exceeds the standard twice in a row or the total number of times the vehicle’s emission level exceeds the standard reaches three times, it is indicated that there is a slight risk of emission exceeding the standard;

If within the first 10 refueling cycles of the vehicle, the vehicle’s emission level exceeds the standard three times in a row or the total number of times the vehicle’s emission level exceeds the standard reaches five times, it will indicate a moderate risk of emission exceeding the standard; and the warning information will be immediately transmitted to Correspond to car companies or relevant environmental protection departments;

If within the first 10 refueling cycles of the vehicle, the vehicle emission level exceeds the standard 5 times in a row or the total number of times the vehicle emission level exceeds the standard reaches 8 times, it will prompt the risk of serious emission exceeding the standard; and the early warning information will be immediately transmitted to the corresponding Car companies or relevant environmental protection departments will continue to issue early warnings until they receive feedback from the corresponding car companies or relevant environmental protection departments.

Optionally, when a risk occurs, early warning information is also immediately delivered to the corresponding owner of the vehicle to prompt the owner to promptly investigate the risk of exceeding emission standards.

This embodiment provides a real-time early warning method for vehicle NOx emission exceeding the standard, which can reorganize the collected fragmented and scattered vehicle data into actual vehicle emission tests that are consistent with the operation logic of the standard test working conditions arrangement in accordance with the requirements of standards and regulations. Working conditions, the actual operating data of the vehicle can be converted into a standard form, and the NOx emission can be calculated and evaluated in accordance with the requirements of standard regulations to obtain timely and accurate emission early warning feedback. In addition, this program is designed to use the sliding window method to determine the NOx emission quality, and to conduct a detailed determination of the NOx emissions in each period of each refueling cycle according to a certain data sampling period, and this program also sets up detailed risk warnings. Indicators can ensure that emission risks are not misjudged or missed.

In addition, this solution adopts a special vehicle driving segment division method, and divides the vehicle driving data multiple times, dividing by refueling cycle, dividing by vehicle speed equal to 0, and dividing by segment dividing conditions. Compared with the conventional scheme, the number of divisions is more, the division details are higher, and the division basis is more special. This makes this scheme not only able to provide accurate early warning for NOx emission exceeding the standard, but also provide reliable data reference for the analysis of the reasons for NOx emission exceeding the standard, because This program creatively discovered the oil product, a factor that has an important impact on NOx emissions exceeding the standard, and by segmenting the vehicle driving data according to the refueling cycle, the oil product factor was naturally and effectively processed, and the oil product factor was The hidden emission influencing factors are externalized into the refueling cycle. Oil products can be easily distinguished through the refueling cycle. By selecting the same refueling cycle data or different refueling cycle data, the impact of oil product factors on excessive emissions can be specifically considered or eliminated. Impact, which can help to more accurately identify the reasons for excessive vehicle NOx emissions from more dimensions, thereby assisting in the scientific monitoring and effective and precise management of vehicle NOx emissions.

Example 2:

A real-time early warning method for vehicle NOx emission exceeding the standard, based on the first embodiment, modifications are made to steps 1 and 2.

When collecting vehicle data in step 1, the location information of the gas stations where the vehicle has stopped is also collected.

In step 2, when confirming the refueling cycle and determining the refueling behavior, after determining that a refueling behavior occurs, the location information of the gas station corresponding to the vehicle when the refueling behavior occurs is obtained and marked in the refueling cycle.

This embodiment provides a real-time early warning method for vehicle NOx emission exceeding the standard. Compared with the first embodiment, the refueling location is additionally determined. If emissions exceed the standard in one or more refueling cycles, the refueling location can be determined. Going to a fixed point to reversely check the oil quality makes it easier to confirm the impact of oil quality factors on excessive emissions.

The above are only embodiments of the present invention. Common knowledge such as the specific structures and characteristics of the solutions are not described in detail here. Those of ordinary skill in the art are aware of all common knowledge in the technical field to which the invention belongs before the filing date or priority date. Technical knowledge, being able to know all the existing technologies in the field, and having the ability to apply conventional experimental methods before that date. Persons of ordinary skill in the field can, under the inspiration given by this application, combine their own abilities to perfect and implement this plan, Some typical well-known structures or well-known methods should not be an obstacle for those of ordinary skill in the art to implement the present application. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention. These should also be regarded as the protection scope of the present invention and will not affect the implementation of the present invention. effectiveness and patented practicality. The scope of protection claimed in this application shall be based on the content of the claims, and the specific implementation modes and other records in the description may be used to interpret the content of the claims.

Claims (9)

1. The real-time early warning method for the exceeding of the NOx emission of the vehicle is characterized by comprising the following steps of:

step 1: collecting vehicle data as a vehicle running data set;

step 2: dividing a vehicle driving data set to obtain a vehicle driving fragment; when dividing, taking a refueling period as a large-segment dividing point; taking the vehicle speed equal to 0 as a small segment cutting point;

step 3: processing the vehicle driving fragments according to the screening processing conditions to obtain effective vehicle driving fragments;

step 4: dividing the effective vehicle driving fragments according to the fragment dividing conditions to obtain a driving fragment group;

step 5: according to a standard working condition construction strategy, selecting effective vehicle driving fragments from the driving fragment groups, and constructing actual emission test working conditions of the vehicle;

step 6: calculating the NOx emission level of the vehicle according to the actual emission test working condition of the vehicle;

step 7: when the NOx emission level of the vehicle does not meet the requirement, carrying out real-time early warning according to an early warning strategy;

in step 2, the refueling period is a driving period between 2 adjacent refueling behaviors of the vehicle; the method for judging the oiling behavior comprises the following steps: firstly, extracting running data fragments with changed oil tank liquid level values from a vehicle running data set, and if the vehicle is stopped before and after, namely, the vehicle speed is equal to the time point before and after, the change amount of the liquid level of the oil tank of the vehicle exceeds 30%, judging that the liquid level value of the oil tank corresponds to one-time oiling behavior.

2. The method for real-time early warning of vehicle NOx emissions exceeding according to claim 1, wherein in step 3, the screening process condition includes deleting reject data from a vehicle driving segment; wherein the unqualified data are data which do not meet the data qualification condition;

the data qualification conditions are as follows:

；

；

；

wherein,the unit is K, which is the ambient temperature of the vehicle; t is standard ambient temperature, and the unit is K; />Is an atmospheric pressure value; h is the altitude of the vehicle; />Is the vehicle engine coolant temperature.

3. The method for real-time early warning of NOx emissions exceeding a standard according to claim 2, wherein the screening condition further comprises deleting the vehicle driving fragment data if the failed data continuously appear in the vehicle driving fragment and the number of points of the failed data continuously exceeds 4% to 6% of the total amount of the vehicle driving fragment data.

4. The method for real-time early warning of NOx emissions over standard according to claim 3, wherein the screening condition further comprises deleting the vehicle driving fragment data if the number of unqualified data points in the vehicle driving fragment exceeds 20% of the total amount of the vehicle driving fragment data.

5. The real-time early warning method for vehicle NOx emissions exceeding according to claim 1, wherein in step 4, the segment division condition is division according to the vehicle type and standard regulation requirements; the resulting driving segment group includes a urban driving segment group, a suburban driving segment group, and a high-speed driving segment group.

6. The method for real-time early warning of vehicle NOx emissions exceeding according to claim 5, wherein in step 5, the standard working condition construction strategy is constructed according to the vehicle model and standard regulation requirements; when the vehicle is assembled, effective vehicle driving fragments are extracted from the urban driving fragment group, the suburban driving fragment group and the high-speed driving fragment group, and the effective vehicle driving fragments are assembled according to the proportion to form the actual emission test working condition of the vehicle.

7. The method for real-time early warning of NOx emissions exceeding in a vehicle according to claim 1, wherein in step 5, when selecting an effective vehicle traveling segment from the traveling segment group, the effective vehicle traveling segment is selected from one fueling cycle; if the effective vehicle driving segment provided in one refueling period is insufficient to construct a complete vehicle actual emission test working condition, the effective vehicle driving segment is acquired from the previous refueling period of the refueling period to construct the complete vehicle actual emission test working condition, and if the refueling period is the first refueling period of the vehicle, the effective vehicle driving segment is acquired from the subsequent refueling period of the refueling period to construct the complete vehicle actual emission test working condition.

8. The method for real-time early warning of vehicle NOx emissions exceeding according to claim 1, wherein in step 6, sliding window method is adopted for calculation when calculating the vehicle NOx emission level.

9. The method according to claim 1, wherein in step 7, the pre-warning strategy comprises: and in the preset number of refueling periods, if the continuous times of exceeding the vehicle emission level is more than or equal to 2 times or the total times of exceeding the vehicle emission level is more than or equal to 3 times, early warning is carried out.