Diesel vehicle emission monitoring method and system

Abstract

The invention belongs to the technical field of vehicle monitoring, and particularly relates to a diesel vehicle emission monitoring method and system.The diesel vehicle emission monitoring method comprises the steps that the air-fuel ratio, the air inlet mass flow rate, the exhaust residual hydrocarbon concentration, the NOx concentration, the concentration, the vehicle speed and the fuel hydrocarbon ratio of a diesel vehicle are collected; the exhaust density is calculated based on the air-fuel ratio, the fuel hydrocarbon ratio and the exhaust residual hydrocarbon concentration; according to the method, the exhaust density is dynamically calculated based on the air-fuel ratio, the fuel hydrocarbon ratio and the exhaust residual hydrocarbon concentration, differential density selection of the fuel cut-off state and the non-fuel cut-off state is combined, changes of exhaust physical and chemical properties of the engine under different working conditions are accurately matched, the calculation accuracy of key parameters such as the exhaust density and the volume flow is remarkably improved, and the calculation efficiency is improved. And a reliable data foundation is laid for pollutant emission accounting.

Description

Technical Field

[0001] This invention belongs to the field of vehicle monitoring technology, specifically relating to a method and system for monitoring emissions from diesel vehicles. Background Technology

[0002] With increasing environmental awareness, effective monitoring of diesel vehicle emissions, especially during real-world driving, has become crucial. Currently, emissions monitoring for diesel vehicles primarily relies on laboratory bench testing or vehicle emission testing systems (PEMS). However, laboratory tests cannot accurately reflect the emission characteristics of vehicles under complex real-world road conditions; and existing PEMS equipment is typically expensive, bulky, and has limitations in its data processing methods.

[0003] Existing emission calculation methods often rely on simplified models or fixed conversion factors, failing to fully consider the dynamic changes in exhaust physicochemical properties under different engine operating conditions (such as normal combustion and coasting with fuel cut-off). This results in insufficient accuracy in calculating key parameters such as exhaust density and volumetric flow rate, thus affecting the accuracy of final pollutant mass emissions. Especially during vehicle idling or low-speed parking, where the vehicle speed is zero or close to zero, distance-based emission calculations become ineffective, easily leading to underestimation of emissions or missing data. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method, system, terminal and storage medium for monitoring emissions of diesel vehicles.

[0005] In a first aspect, the present invention provides a method for monitoring emissions from diesel vehicles, comprising: S1. Collect data on the air-fuel ratio, intake air mass flow rate, exhaust residual hydrocarbon concentration, and NOx concentration of diesel vehicles. Concentration, vehicle speed, and fuel hydrocarbon ratio; S2. Calculate the exhaust density based on the air-fuel ratio, fuel hydrocarbon ratio, and exhaust residual hydrocarbon concentration; S3. Calculate the exhaust mass flow rate based on the intake mass flow rate and air-fuel ratio, and calculate the exhaust volume flow rate based on the exhaust mass flow rate and exhaust density. S4, combined with exhaust volume flow rate and NOx concentration. Concentration and standard density, calculate NOx mass emissions per unit time and Mass emissions; S5. Based on vehicle speed, calculate the NOx mass emissions per unit time and Mass emissions are converted into corresponding mass emissions per unit distance and accumulated as points during the parking phase; S6. Obtain the GPS location information of diesel vehicles, bind the unit distance mass emission to the GPS location information, and aggregate the emission data according to the preset spatial granularity to generate an emission heat map of diesel vehicles.

[0006] Further improvements to this technical solution include step S1, which includes: S11. Real-time measurement of air-fuel ratio in exhaust gas using a wide-range air-fuel ratio sensor. And the residual hydrocarbon concentration in the exhaust gas is detected by an FID sensor. ; S12. Read the intake air mass flow rate through the OBD system of the diesel vehicle. NOx concentration and concentration And simultaneously obtain vehicle speed and engine operating status; S13, adjust the fuel's carbon-to-hydrogen ratio The default value is a fixed value or it can be configured based on the real-time fuel type. This indicates the number of carbon atoms in each fuel molecule. Indicates the number of hydrogen atoms.

[0007] Further improvements to this technical solution include step S2, which includes: S21, Based on air-fuel ratio And fuel hydrocarbon ratio A combustion reaction model is constructed to determine the molar percentage of each component in the exhaust gas. The combustion reaction equation in the combustion reaction model is as follows: ; in, Indicates the molecular composition of diesel fuel; For excess air ratio, ,in, The preset theoretical air-fuel ratio; Represents oxygen molecules; Represents nitrogen molecules; Indicates the oxygen concentration in the air; This represents the ratio of nitrogen to oxygen. ; This represents carbon dioxide molecules, where 'a' is the number of moles. denoted as carbon monoxide molecules, where b is its molar number; Let c represent the number of water molecules; This represents hydrogen molecules, where d is their molar number; e represents oxygen molecules. The number of moles; f is nitrogen gas. The number of moles; The term represents the residual hydrocarbon molecules in the exhaust gas, where r is the number of carbon atoms in the residual hydrocarbon molecule, s is the number of hydrogen atoms in the residual hydrocarbon molecule, and g is its molar number. S22, Combining exhaust residual hydrocarbon concentration T and hydrocarbon correction factor After correcting the mole fractions of each component, we obtain... mole fraction , mole fraction , mole fraction , mole fraction ,satisfy Where M is the total number of moles; and where the hydrocarbon correction factor is... The calculation formula is: ; S23. Calculate the exhaust density based on the mole fraction and molar mass of each component. Exhaust density The calculation formula is: ; in, for molar mass; for molar mass; for molar mass; for molar mass; For standard molar volume, .

[0008] Further improvements to this technical solution include step S3, which includes: S31. Based on the law of conservation of intake mass, and combining intake mass flow rate and air-fuel ratio, the exhaust mass flow rate is calculated using the following formula: ; in, This refers to the exhaust mass flow rate; S32, vehicle speed The system determines whether the vehicle is in a fuel cut-off state based on the engine's operating status, and selects the exhaust density parameter accordingly: In the non-fuel cut-off state, the exhaust density calculated in step S23 is used. When fuel is cut off, air density is used. ; S33, based on exhaust mass flow rate The exhaust volume flow rate is calculated based on the exhaust density corresponding to the fuel cut-off state. The calculation formula is as follows: ; ; in, The exhaust volume flow rate under non-fuel cut-off conditions, in units of ; The exhaust volume flow rate under fuel-cut-off conditions, in units of Under fuel cut-off conditions, exhaust mass flow rate Using intake mass flow rate .

[0009] Further improvements to this technical solution include step S4, which includes: S41. Obtain the exhaust volume flow rate and perform state correction. In the non-fuel cut-off state, use the calculation in S33. Used in the state of fuel cut-off , uniformly recorded as ; S42, Confirm Standard density parameters as well as Standard density parameters ; S43. Based on NOx concentration and concentration and their respective standard density parameters, combined with exhaust volume flow rate. Calculate NOx and The corresponding mass emissions per unit time: ; ; in, This refers to the mass emission of NOx per unit time. For a unit of time The mass of emissions.

[0010] Further improvements to this technical solution include step S5, which includes: S51. Preprocess the collected vehicle speed signals, converting the vehicle speed units to a uniform value. The vehicle speed is then smoothed by removing instantaneous fluctuations through a moving average filter. ; S52. Determine the vehicle's operating status, and adjust the smoothed vehicle speed. When the vehicle is in a driving state, the mass emission per unit time is converted into the emission per unit distance using the following formula: ; ; in, NOx emissions per unit distance; for Emissions per unit distance; S53, after smoothing out the vehicle speed When the vehicle is in a stopped state, the cumulative emissions are calculated by integrating the mass emissions per unit time. The calculation formula is as follows: ; ; in, This represents the cumulative NOx emissions during the shutdown phase. Parking phase Cumulative emissions; This is the start time of parking; This is the time when parking ends; The sampling time interval; , NOx and NOx at time t are respectively Emissions per unit time.

[0011] Further improvements to this technical solution include step S6, which includes: S61. Collect real-time location information of diesel vehicles through GPS module, including longitude L and latitude B, and record the corresponding timestamp t; S62. Bind the unit distance mass or cumulative emission mass during the parking phase with GPS location information and timestamp t to generate a spatiotemporal emission data matrix D, in the form of: ; in, For the first Timestamps of each data point; , The first The longitude and latitude of each data point; , The first The sum of the data points and the corresponding unit distance quality; S63. Aggregate the spatiotemporal emission data matrix D according to the preset spatial granularity, and calculate the total emissions within each grid. The calculation formula is as follows: ; ; ; ; in, , NOx and within the grid, respectively The total emissions are used to generate an emissions heatmap based on the aggregation results.

[0012] Secondly, the present invention provides an emission monitoring system for diesel vehicles, comprising: The data acquisition module is used to collect data on the air-fuel ratio, intake air mass flow rate, exhaust residual hydrocarbon concentration, and NOx concentration of diesel vehicles. Concentration, vehicle speed, and fuel hydrocarbon ratio; The exhaust density calculation module is used to calculate exhaust density based on air-fuel ratio, fuel hydrocarbon ratio, and exhaust residual hydrocarbon concentration. The exhaust volume flow rate calculation module is used to calculate the exhaust mass flow rate based on the intake mass flow rate and air-fuel ratio, and to calculate the exhaust volume flow rate based on the exhaust mass flow rate and exhaust density. The mass emission calculation module is used to combine exhaust volume flow rate, NOx concentration, Concentration and standard density, calculate NOx mass emissions per unit time and Mass emissions; The unit distance mass emission calculation module is used to calculate the NOx mass emissions per unit time based on vehicle speed. Mass emissions are converted into corresponding mass emissions per unit distance and accumulated as points during the parking phase; The emissions data aggregation module is used to acquire the GPS location information of diesel vehicles, bind the mass emissions per unit distance with the GPS location information, and aggregate the emissions data according to the preset spatial granularity to generate an emissions heat map of diesel vehicles.

[0013] Thirdly, the present invention provides a terminal, comprising: Processor, memory, among which, This memory is used to store computer programs. The processor is used to retrieve and run the computer program from memory, causing the terminal to perform the terminal method described above.

[0014] Fourthly, the present invention provides a computer storage medium storing instructions that, when executed on a computer, cause the computer to perform the methods described in the above aspects.

[0015] The beneficial effects of this invention are as follows: This invention breaks through the limitations of traditional fixed conversion factors. It dynamically calculates exhaust density based on air-fuel ratio, fuel hydrocarbon ratio, and exhaust residual hydrocarbon concentration. Combined with differentiated density selection under fuel cut-off and non-fuel cut-off conditions, it accurately matches the changes in exhaust physicochemical properties under different engine operating conditions, significantly improving the calculation accuracy of key parameters such as exhaust density and volumetric flow rate, and laying a reliable data foundation for pollutant emission accounting.

[0016] To address the issue of distance-based emission calculation failures when vehicles are idling or driving at low speeds, the system distinguishes between driving and parking states by vehicle speed. During the parking phase, emissions are accumulated using a time integration method, which avoids underestimation of emissions or data loss, and achieves complete capture of emission data under all operating conditions.

[0017] By binding GPS location information with cumulative emissions per unit distance / parking data, emissions heat maps are generated according to preset spatial granularity, clearly showing the spatial distribution of pollution hotspots. This provides an intuitive and accurate basis for targeted governance of urban traffic pollution, and promotes the transformation of emission control from "vague total amount" to "precise spatiotemporal control".

[0018] This invention is based on the collaborative acquisition of data from a wide-range air-fuel ratio sensor, an FID sensor, and the vehicle's OBD system, eliminating the need for complex and expensive discrete devices and simplifying hardware configuration. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart illustrating a method according to an embodiment of the present invention.

[0021] Figure 2 This is the schematic diagram of the AD acquisition circuit.

[0022] Figure 3 This is a schematic diagram of a CAN communication circuit.

[0023] Figure 4 This is the schematic diagram of the power supply circuit.

[0024] Figure 5 This is a schematic diagram of the calculation process of the method.

[0025] Figure 6 A schematic diagram illustrating the process for determining a vehicle's fuel cut-off status.

[0026] Figure 7 This is a schematic block diagram of a system according to an embodiment of the present invention.

[0027] Figure 8 This is a schematic diagram of the structure of a terminal provided in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0030] Figure 1 This is a schematic flowchart illustrating a method for monitoring emissions from diesel vehicles provided by the present invention. Wherein, Figure 1 The implementing entity can be an emissions monitoring system for diesel vehicles. Depending on different requirements, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0031] like Figure 1 As shown, the method includes: S1. Collect data on the air-fuel ratio, intake air mass flow rate, exhaust residual hydrocarbon concentration, and NOx concentration of diesel vehicles. (Carbon dioxide) concentration, vehicle speed, and fuel hydrocarbon ratio; S2. Calculate the exhaust density based on the air-fuel ratio, fuel hydrocarbon ratio, and exhaust residual hydrocarbon concentration; S3. Calculate the exhaust mass flow rate based on the intake mass flow rate and air-fuel ratio, and calculate the exhaust volume flow rate based on the exhaust mass flow rate and exhaust density. S4, combined with exhaust volume flow rate and NOx concentration. Concentration and standard density, calculate NOx mass emissions per unit time and Mass emissions; S5. Based on vehicle speed, calculate the NOx mass emissions per unit time and Mass emissions are converted into corresponding mass emissions per unit distance and accumulated as points during the parking phase; S6. Obtain the GPS location information of diesel vehicles, bind the unit distance mass emission to the GPS location information, and aggregate the emission data according to the preset spatial granularity to generate an emission heat map of diesel vehicles.

[0032] To facilitate understanding of the present invention, the following description further illustrates the emission monitoring method for diesel vehicles provided by the present invention, based on the principle of the method and the process of monitoring emissions from diesel vehicles in the embodiments.

[0033] First, step S1 includes: S11. Real-time measurement of air-fuel ratio in exhaust gas using a wide-range air-fuel ratio sensor. And the residual hydrocarbon concentration in the exhaust gas is detected by an FID sensor. ; S12. Read the intake air mass flow rate through the OBD system of the diesel vehicle. NOx concentration and concentration And simultaneously obtain vehicle speed and engine operating status; S13, adjust the fuel's carbon-to-hydrogen ratio The default value is a fixed value or it can be configured based on the real-time fuel type. This indicates the number of carbon atoms in each fuel molecule. Indicates the number of hydrogen atoms.

[0034] Secondly, step S2 includes: S21, Based on air-fuel ratio And fuel hydrocarbon ratio A combustion reaction model is constructed to determine the molar percentage of each component in the exhaust gas. The combustion reaction equation in the combustion reaction model is as follows: ; in, Indicates the molecular composition of diesel fuel; For excess air ratio, ,in, The preset theoretical air-fuel ratio; Represents oxygen molecules; Represents nitrogen molecules; Indicates the oxygen concentration in the air; This represents the ratio of nitrogen to oxygen. ; This represents carbon dioxide molecules, where 'a' is the number of moles. denoted as carbon monoxide molecules, where b is its molar number; Let c represent the number of water molecules; This represents hydrogen molecules, where d is their molar number; e represents oxygen molecules. The number of moles; f is nitrogen gas. The number of moles; The term represents the residual hydrocarbon molecules in the exhaust gas, where r is the number of carbon atoms in the residual hydrocarbon molecule, s is the number of hydrogen atoms in the residual hydrocarbon molecule, and g is its molar number. S22, Combining exhaust residual hydrocarbon concentration T and hydrocarbon correction factor After correcting the mole fractions of each component, we obtain... mole fraction , mole fraction , mole fraction , mole fraction ,satisfy Where M is the total number of moles; and where the hydrocarbon correction factor is... The calculation formula is: ; S23. Calculate the exhaust density based on the mole fraction and molar mass of each component. Exhaust density The calculation formula is: ; in, for molar mass; for molar mass; for molar mass; for molar mass; For standard molar volume, .

[0035] Next, step S3 includes: S31. Based on the law of conservation of intake mass, and combining intake mass flow rate and air-fuel ratio, the exhaust mass flow rate is calculated using the following formula: ; in, This refers to the exhaust mass flow rate; S32, vehicle speed And determine whether the vehicle is in a fuel cut-off state based on engine operating status (the fuel cut-off state determination condition is "vehicle speed"). Accelerator pedal opening is zero, engine speed is zero. And fuel injection stops), and the exhaust density parameter is selected according to the fuel cut-off state: the exhaust density calculated in step S23 is used in the non-fuel cut-off state. When fuel is cut off, air density is used. ; S33, based on exhaust mass flow rate The exhaust volume flow rate is calculated based on the exhaust density corresponding to the fuel cut-off state. The calculation formula is as follows: ; ; in, The exhaust volume flow rate under non-fuel cut-off conditions, in units of ; The exhaust volume flow rate under fuel-cut-off conditions, in units of Under fuel cut-off conditions, exhaust mass flow rate Using intake mass flow rate .

[0036] Then, step S4 includes: S41. Obtain the exhaust volume flow rate and perform state correction. In the non-fuel cut-off state, use the calculation in S33. Used in the state of fuel cut-off , uniformly recorded as ; S42, Confirm Standard density parameters as well as Standard density parameters ; S43. Based on NOx concentration and concentration and their respective standard density parameters, combined with exhaust volume flow rate. Calculate NOx and The corresponding mass emissions per unit time: ; ; in, This refers to the mass emission of NOx per unit time. For a unit of time The mass of emissions.

[0037] Additionally, step S5 includes: S51. Preprocess the collected vehicle speed signals, converting the vehicle speed units to a uniform value. The vehicle speed is then smoothed by removing instantaneous fluctuations through a moving average filter. ; S52. Determine the vehicle's operating status, and adjust the smoothed vehicle speed. When the vehicle is in a driving state, the mass emission per unit time is converted into the emission per unit distance using the following formula: ; ; in, NOx emissions per unit distance; for Emissions per unit distance; S53, after smoothing out the vehicle speed When the vehicle is in a stopped state, the cumulative emissions are calculated by integrating the mass emissions per unit time. The calculation formula is as follows: ; ; in, This represents the cumulative NOx emissions during the shutdown phase. Parking phase Cumulative emissions; This is the start time of parking; This is the time when parking ends; The sampling time interval; , NOx and NOx at time t are respectively Emissions per unit time.

[0038] Finally, step S6 includes: S61. Collect real-time location information of diesel vehicles through GPS module, including longitude L and latitude B, and record the corresponding timestamp t; S62. Bind the unit distance mass or cumulative emission mass during the parking phase with GPS location information and timestamp t to generate a spatiotemporal emission data matrix D, in the form of: ; in, For the first Timestamps of each data point; , The first The longitude and latitude of each data point; , The first The sum of the data points and the corresponding unit distance quality; S63. Aggregate the spatiotemporal emission data matrix D according to the preset spatial granularity, and calculate the total emissions within each grid. The calculation formula is as follows: ; ; ; ; in, , NOx and within the grid, respectively The total emissions are aggregated, and an emissions heatmap is generated based on the aggregation results to achieve spatial visualization of diesel vehicle emission hotspots.

[0039] This invention proposes a convenient real-time emission monitoring device and method for diesel vehicles. This method achieves lightweight, high-resolution pollution monitoring and spatial source tracing through multi-source data fusion and algorithm innovation. Specifically, it includes the following two core steps: multi-parameter collaborative measurement and data preprocessing at the on-board emission test and analysis terminal, and mapping of distance emission factors and spatial pollution hotspots.

[0040] 1. Multi-parameter collaborative measurement and data preprocessing for vehicle-mounted emission testing and analysis terminal: The vehicle-mounted emissions analysis terminal consists of a processor and peripheral sensors. The processor uses an STM32F407ZGT6 as its core unit. The STM32F407ZGT6 is a high-performance ARM Cortex-M4 core microcontroller from STMicroelectronics, with a clock speed of 168 MHz. It integrates a hardware floating-point unit (FPU) and DSP instructions, supporting complex algorithms and real-time control. It is equipped with 1MB Flash, 192KB RAM, and rich peripherals, including USB OTG HS, Ethernet MAC, camera interface (DCMI), and high-speed ADC / DAC. It uses a 144-pin LQFP package and is suitable for high-performance embedded scenarios such as industrial automation, consumer electronics, and the Internet of Things. Peripheral processing circuits include AD acquisition circuits (such as...). Figure 2 As shown), CAN communication circuit (such as) Figure 3 As shown), power supply circuit (such as) Figure 4 As shown), the 485 communication circuit includes sensors including an FID sensor, a wide air-fuel ratio sensor, and a GNSS acquisition module and a GNSS antenna.

[0041] The on-board emission analysis terminal obtains engine speed, vehicle speed, pedal opening, NOx concentration, intake air flow, and whether fuel injection is in progress from the vehicle's OBD via CAN communication. It also acquires the air-fuel ratio and exhaust residual hydrocarbon concentration in real time via AD acquisition and obtains the real-time location from the GNSS module via 485 communication. The terminal performs comprehensive analysis on the above data and transmits the analysis results to the display terminal in real time to obtain a real-time emission heat map.

[0042] The following is the calculation process; the specific calculation flow is as follows: Figure 5 As shown: In road driving tests using on-board emission analysis terminals, the volumetric flow rate of exhaust gas is required to calculate mass emissions based on the concentration of exhaust gas components. The intake air mass flow rate (often called MAF) and NOx concentration are obtained through the OBD port, and the volumetric flow rate of exhaust gas is obtained using the following formula:

[0043]

[0044]

[0045]

[0046] In the formula, Air-fuel ratio; Intake mass flow rate (g / s) (MAF); The exhaust mass flow rate is (g / s). Fuel mass flow rate (g / s); The hydrogen / carbon ratio of the fuel; The calculated exhaust volume flow rate (m³ / s); The exhaust density is (g / m3).

[0047] Equation (2) is based on the law of conservation of mass. The calculation method proposed in this invention is also characterized by Equation (4), that is, the exhaust density is obtained as a function of the air-fuel ratio and the hydrogen / carbon ratio of the fuel. In commercially available testing systems, the exhaust density is independent of the engine's combustion state and air-fuel ratio and is set as a constant value. It has the same density as air; however, the exhaust density is greatly affected by the composition of the exhaust.

[0048] Electronically controlled diesel vehicles cut off fuel supply during deceleration. The exhaust volumetric flow rate during fuel cutoff is calculated using formulas (5) and (6). Let be the air density. All exhaust during fuel cut-off is assumed to be air, and the exhaust mass flow rate is equal to the intake mass flow rate.

[0049]

[0050]

[0051] Methods for determining fuel cut-off include: Figure 6 As shown.

[0052] The method for calculating exhaust gas density is as follows: Generally speaking, combustion is the process of burning fuel ( ) and air ( The oxidation reaction of ). At the stoichiometric air-fuel ratio ( When =1), carbon dioxide is emitted ( ),water vapor( ) and nitrogen ( When there is excessive air ( When >1), residual oxygen is discharged ( When air is insufficient ( When <1), carbon monoxide is emitted ( In addition to the components mentioned above, it also emits hydrogen gas. The composition of the exhaust gas varies with λ, and the concentration of each component can be expressed as the excess air ratio. Since the amount of residual hydrocarbons varies depending on the engine's combustion conditions, and because the amount of residual hydrocarbons emitted is small, their contribution to the airflow is also small.

[0053] Since this invention revolves around diesel engines, which are in a lean-burn state during normal operation, this invention describes the calculation of exhaust density under lean-burn conditions.

[0054]

[0055] Where a is Number of moles; b is The number of moles; c is The number of moles; d is The number of moles; e is The number of moles; f is The molar number of ; g is the molar number of residual hydrocarbons; p is the number of carbon atoms in each fuel molecule; q is the number of hydrogen atoms in each fuel molecule; r is the number of carbon atoms in the residual hydrocarbons; s is the number of hydrogen atoms in the residual hydrocarbons; The excess air ratio is calculated using the air-fuel ratio obtained from a wide-range air-fuel ratio sensor.

[0056] In lean combustion ( Under the condition of ≥1), the total amount of combustion gases ( ) can be expressed as formula (8).

[0057]

[0058] The concentrations of each gas component are as follows: ; ; ; ; ; in, The carbon-hydrogen ratio of fuel ( =q / p); r is the number of carbon atoms in the residual hydrocarbon (set to 1.85 typical for diesel vehicles under lean-burn conditions); Total exhaust hydrocarbon concentration (methane standard); This refers to the oxygen concentration in the air.

[0059] Finally, the exhaust density under lean-burn conditions can be expressed as formula (15): ; The above formula allows for real-time acquisition of exhaust gas density and CO2 concentration, providing data support for subsequent calculations.

[0060] 2. Mapping of distance emission factors and spatial pollution hotspots: The original purpose of using onboard emissions analysis terminals for road testing was to understand the location and amount of exhaust gas components emitted in the actual environment. The measurement results, obtained through the above calculations, are in the form of emissions per unit time (g / s). However, to meet the aforementioned objective, it is necessary to analyze emissions per unit distance (g / m). In other words, by combining emissions per unit distance with GPS location information, it is possible to determine the location of significant exhaust gas emissions.

[0061] This invention uses NOx concentration, Concentration and exhaust volume flow rate Calculate the mass emissions per unit time.

[0062] ; ; in, : / concentration; , Time-based / Mass emissions (g / s); , NOx / CO2 density (g / m3).

[0063] Next, the emission mass per unit distance is calculated by dividing the time-based emission mass by the vehicle speed (Equations 18 and 19). However, this formula diverges when the vehicle is stationary or the speed is close to zero, therefore the time-based emission mass needs to be integrated with the parking time and calculated as the emission at the parking point (Equations 20 and 21). In this invention, the vehicle speed is below 2... When it is defined as parking.

[0064] ; ; ; ; In the formula, , Distance-based / Mass emissions (g / m³); , When the vehicle is stopped / Mass emissions (g); : Time (sec) during vehicle startup; : The time (in seconds) during which the vehicle came to a stop; Vehicle speed (m / s).

[0065] The onboard emissions analysis terminal obtains the emissions factor per second ( After obtaining the data (g / s), it is linked to the GPS location to generate a spatiotemporal matrix: timestamp, longitude, latitude, and NOx emissions (g / s). Emissions (g / s) and vehicle speed (m / s) are accumulated in 10-meter segments and transmitted to a display terminal via CAN communication to generate a pollution intensity heat map, thus clearly exposing high-emission road sections. This achieves meter-level spatiotemporal analysis of pollutant emissions and successfully locates high-emission hotspots on actual roads.

[0066] This invention belongs to the field of vehicle-mounted emission real-time monitoring and road pollution analysis technology, specifically involving a lightweight multi-parameter emission measurement and spatial positioning analysis method based on sensor networks. Traditional portable emission measurement systems rely on heavy equipment, significantly altering vehicle load and affecting the accuracy of actual road emission data; while laboratory chassis dynamometer testing can accurately sample emissions, it cannot reflect the impact on aftertreatment device temperatures and other factors under real-world driving conditions. This research proposes a convenient real-time emission monitoring device and method for diesel vehicles. Through a self-developed vehicle-mounted emission testing and analysis terminal, it integrates exhaust residual hydrocarbon concentration obtained from FID sensors, air-fuel ratio obtained from wide-range air-fuel ratio sensors, OBD real-time data (engine speed, vehicle speed, accelerator pedal opening, NOx concentration, intake air flow, and whether fuel injection is in progress), and GPS spatial positioning to achieve real-time calculation of exhaust flow. The system enables real-time calculation of concentration inversion and spatial mapping of local pollution hotspots, achieving three major technological breakthroughs: lightweight equipment, strong adaptability to operating conditions, and accurate pollution source tracing.

[0067] In some embodiments, the emission monitoring system 200 for diesel vehicles may include multiple functional modules composed of computer program segments. The computer programs for each program segment in the emission monitoring system 200 may be stored in the memory of a computer device and executed by at least one processor to perform (see details). Figure 1 (Description) The function of monitoring emissions from diesel vehicles.

[0068] In this embodiment, the emission monitoring system 200 for diesel vehicles can be divided into multiple functional modules according to the functions it performs, such as... Figure 7As shown. The functional modules may include: a data acquisition module 210, an exhaust density calculation module 220, an exhaust volume flow rate calculation module 230, a mass emission calculation module 240, a unit distance mass emission calculation module 250, and an emission data aggregation module 260. The module referred to in this invention is a series of computer program segments that can be executed by at least one processor and perform a fixed function, stored in memory. In this embodiment, the functions of each module will be described in detail in subsequent embodiments.

[0069] Specifically, the data acquisition module 210 is used to collect data on the air-fuel ratio, intake air mass flow rate, exhaust residual hydrocarbon concentration, and NOx concentration of diesel vehicles. The system includes modules for calculating exhaust density based on air-fuel ratio, fuel hydrocarbon ratio, and residual hydrocarbon concentration; an exhaust volume flow rate calculation module 230 calculates exhaust mass flow rate based on intake mass flow rate and air-fuel ratio, and calculates exhaust volume flow rate based on exhaust mass flow rate and exhaust density; and a mass emission calculation module 240 combines exhaust volume flow rate, NOx concentration, and vehicle speed. Concentration and standard density, calculate NOx mass emissions per unit time and NOx emissions per unit distance; Module 250 for calculating NOx emissions per unit time based on vehicle speed. Mass emissions are converted into corresponding unit distance mass emissions and accumulated during the parking phase; the emission data aggregation module 260 is used to obtain the GPS location information of diesel vehicles, bind the unit distance mass emissions with the GPS location information, and aggregate the emission data according to the preset spatial granularity to generate the emission heat map of diesel vehicles.

[0070] Figure 8 This is a schematic diagram of the structure of a terminal 300 provided in an embodiment of the present invention. The terminal 300 can be used to execute the emission monitoring method for diesel vehicles provided in the embodiment of the present invention.

[0071] The terminal 300 may include a processor 310, a memory 320, and a communication module 330. These components communicate via one or more buses. Those skilled in the art will understand that the server structure shown in the figure does not constitute a limitation of the present invention. It may be a bus topology or a star topology, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0072] The memory 320 can be used to store the execution instructions of the processor 310. The memory 320 can be implemented by any type of volatile or non-volatile memory terminal or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. When the execution instructions in the memory 320 are executed by the processor 310, the terminal 300 is able to perform some or all of the steps in the above method embodiments.

[0073] The processor 310 serves as the control center of the storage terminal, connecting various parts of the electronic terminal via various interfaces and lines. It executes software programs and / or modules stored in the memory 320, and calls data stored in the memory to perform various functions of the electronic terminal and / or process data. The processor can be composed of integrated circuits (ICs), such as a single packaged IC or multiple packaged ICs with the same or different functions connected together. For example, the processor 310 may consist only of a central processing unit (CPU). In this embodiment of the invention, the CPU may have a single processing core or include multiple processing cores.

[0074] The communication module 330 is used to establish a communication channel, enabling the storage terminal to communicate with other terminals. It receives user data sent by other terminals or sends user data to other terminals.

[0075] The present invention also provides a computer storage medium, wherein the computer storage medium may store a program, which, when executed, may include some or all of the steps provided in the embodiments of the present invention. The storage medium may be a magnetic disk, an optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0076] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium such as a USB flash drive, mobile hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, or other media capable of storing program code. It includes several instructions to cause a computer terminal (which may be a personal computer, server, or a second terminal, network terminal, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0077] The same or similar parts between the various embodiments in this specification can be referred to mutually. In particular, the terminal embodiments are basically similar to the method embodiments, so the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0078] In the embodiments provided by this invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between systems or modules may be electrical, mechanical, or other forms.

[0079] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0080] In addition, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0081] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for monitoring emissions from diesel vehicles, characterized in that, include: S1. Collect data on the air-fuel ratio, intake air mass flow rate, exhaust residual hydrocarbon concentration, and NOx concentration of diesel vehicles. Concentration, vehicle speed, and fuel hydrocarbon ratio; S2. Calculate the exhaust density based on the air-fuel ratio, fuel hydrocarbon ratio, and exhaust residual hydrocarbon concentration; S3. Calculate the exhaust mass flow rate based on the intake mass flow rate and air-fuel ratio, and calculate the exhaust volume flow rate based on the exhaust mass flow rate and exhaust density. S4, combined with exhaust volume flow rate and NOx concentration. Concentration and standard density, calculate NOx mass emissions per unit time and Mass emissions; S5. Based on vehicle speed, calculate the NOx mass emissions per unit time and Mass emissions are converted into corresponding mass emissions per unit distance and accumulated as points during the parking phase; S6. Obtain the GPS location information of diesel vehicles and bind the unit distance mass emission to the GPS location information; The emission data is aggregated according to a preset spatial granularity to generate an emission heat map of diesel vehicles.

2. The emission monitoring method for diesel vehicles according to claim 1, characterized in that, Step S1 includes: S11. Real-time measurement of air-fuel ratio in exhaust gas using a wide-range air-fuel ratio sensor. And the residual hydrocarbon concentration in the exhaust gas is detected by an FID sensor. ; S12. Read the intake air mass flow rate through the OBD system of the diesel vehicle. NOx concentration and concentration And simultaneously obtain vehicle speed and engine operating status; S13, adjust the fuel's carbon-to-hydrogen ratio The default value is a fixed value or it can be configured based on the real-time fuel type. This indicates the number of carbon atoms in each fuel molecule. Indicates the number of hydrogen atoms.

3. The emission monitoring method for diesel vehicles according to claim 2, characterized in that, Step S2 includes: S21, Based on air-fuel ratio And fuel hydrocarbon ratio A combustion reaction model is constructed to determine the molar percentage of each component in the exhaust gas. The combustion reaction equation in the combustion reaction model is as follows: ； in, Indicates the molecular composition of diesel fuel; For excess air ratio, ,in, The preset theoretical air-fuel ratio; Represents oxygen molecules; Represents nitrogen molecules; Indicates the oxygen concentration in the air; This represents the ratio of nitrogen to oxygen. ; This represents carbon dioxide molecules, where 'a' is the number of moles. denoted as carbon monoxide molecules, where b is its molar number; Let c represent the number of water molecules; This represents hydrogen molecules, where d is their molar number; e represents oxygen molecules. The number of moles; f is nitrogen gas. The number of moles; The term represents the residual hydrocarbon molecules in the exhaust gas, where r is the number of carbon atoms in the residual hydrocarbon molecule, s is the number of hydrogen atoms in the residual hydrocarbon molecule, and g is its molar number. S22, Combining exhaust residual hydrocarbon concentration T and hydrocarbon correction factor After correcting the mole fractions of each component, we obtain... mole fraction , mole fraction , mole fraction , mole fraction ,satisfy Where M is the total number of moles; and where the hydrocarbon correction factor is... The calculation formula is: ； S23. Calculate the exhaust density based on the mole fraction and molar mass of each component. exhaust density The calculation formula is: ； in, for molar mass; for molar mass; for molar mass; for molar mass; For standard molar volume, .

4. The emission monitoring method for diesel vehicles according to claim 3, characterized in that, Step S3 includes: S31. Based on the law of conservation of intake mass, and combining intake mass flow rate and air-fuel ratio, the exhaust mass flow rate is calculated using the following formula: ； in, This refers to the exhaust mass flow rate; S32, vehicle speed The system determines whether the vehicle is in a fuel cut-off state based on the engine's operating status, and selects the exhaust density parameter accordingly: In the non-fuel cut-off state, the exhaust density calculated in step S23 is used. When fuel is cut off, air density is used. ; S33, based on exhaust mass flow rate The exhaust volume flow rate is calculated based on the exhaust density corresponding to the fuel cut-off state. The calculation formula is as follows: ； ； in, The exhaust volume flow rate under non-fuel cut-off conditions, in units of ; The exhaust volume flow rate under fuel-cut-off conditions, in units of Under fuel cut-off conditions, exhaust mass flow rate Using intake mass flow rate .

5. The emission monitoring method for diesel vehicles according to claim 4, characterized in that, Step S4 includes: S41. Obtain the exhaust volume flow rate and perform state correction. In the non-fuel cut-off state, use the calculation in S33. Used in the state of fuel cut-off , uniformly recorded as ; S42, Confirm Standard density parameters as well as Standard density parameters ; S43. Based on NOx concentration and concentration and their respective standard density parameters, combined with exhaust volume flow rate. Calculate NOx and The corresponding mass emissions per unit time: ； ； in, This refers to the mass emission of NOx per unit time. For a unit of time The mass of emissions.

6. The emission monitoring method for diesel vehicles according to claim 5, characterized in that, Step S5 includes: S51. Preprocess the collected vehicle speed signals, converting the vehicle speed units to a uniform value. The vehicle speed is then smoothed by removing instantaneous fluctuations through a moving average filter. ; S52. Determine the vehicle's operating status, and adjust the smoothed vehicle speed. When the vehicle is in a driving state, the mass emission per unit time is converted into the emission per unit distance using the following formula: ； ； in, NOx emissions per unit distance; for Emissions per unit distance; S53, after smoothing out the vehicle speed When the vehicle is in a stopped state, the cumulative emissions are calculated by integrating the mass emissions per unit time. The calculation formula is as follows: ； ； in, This represents the cumulative NOx emissions during the shutdown phase. Parking phase Cumulative emissions; This is the start time of parking; This is the time when parking ends; The sampling time interval; , NOx and NOx at time t are respectively Emissions per unit time.

7. The emission monitoring method for diesel vehicles according to claim 6, characterized in that, Step S6 includes: S61. Collect real-time location information of diesel vehicles through GPS module, including longitude L and latitude B, and record the corresponding timestamp t; S62. Bind the unit distance mass or cumulative emission mass during the parking phase with GPS location information and timestamp t to generate a spatiotemporal emission data matrix D, in the form of: ； in, For the first Timestamps of each data point; , The first The longitude and latitude of each data point; , The first The sum of the data points and the corresponding unit distance quality; S63. Aggregate the spatiotemporal emission data matrix D according to the preset spatial granularity, and calculate the total emissions within each grid. The calculation formula is as follows: ； ； ； ； in, , NOx and within the grid, respectively The total emissions are used to generate an emissions heatmap based on the aggregation results.

8. An emission monitoring system for diesel vehicles, characterized in that, include: The data acquisition module is used to collect data on the air-fuel ratio, intake air mass flow rate, exhaust residual hydrocarbon concentration, and NOx concentration of diesel vehicles. Concentration, vehicle speed, and fuel hydrocarbon ratio; The exhaust density calculation module is used to calculate exhaust density based on air-fuel ratio, fuel hydrocarbon ratio, and exhaust residual hydrocarbon concentration. The exhaust volume flow rate calculation module is used to calculate the exhaust mass flow rate based on the intake mass flow rate and air-fuel ratio, and to calculate the exhaust volume flow rate based on the exhaust mass flow rate and exhaust density. The mass emission calculation module is used to combine exhaust volume flow rate, NOx concentration, Concentration and standard density, calculate NOx mass emissions per unit time and Mass emissions; The unit distance mass emission calculation module is used to calculate the NOx mass emissions per unit time based on vehicle speed. Mass emissions are converted into corresponding mass emissions per unit distance and accumulated as points during the parking phase; The emissions data aggregation module is used to obtain the GPS location information of diesel vehicles and bind the mass emissions per unit distance with the GPS location information; The emission data is aggregated according to a preset spatial granularity to generate an emission heat map of diesel vehicles.

9. A terminal, characterized in that, include: processor; Memory used to store the processor's execution instructions; The processor is configured to perform the method of any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-7.

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