Method for converting different measurement units of motor vehicle exhaust emission based on microscopic operation mode

Abstract

The invention relates to the technical field of motor vehicles, in particular to a method for converting different measurement units of motor vehicle exhaust emission based on a microscopic operation mode. According to the method, the emission characteristics of the motor vehicle under different working conditions can be accurately reflected through the division of the microcosmic operation modes; through working condition normalization and unit conversion, data barriers among different detection means and different supervision links are broken, and transverse comparison of emission calculation results formed by different emission measurement units and test working conditions is realized; the method is suitable for the measurement unit conversion of pollutant emission test data of mobile sources including motor vehicles, non-road mobile machinery and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of motor vehicles, and particularly to a method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operation modes. Background Art

[0002] Motor vehicle exhaust emissions are one of the main sources of urban air pollution. Due to different detection technical methods, emission test requirements are also different, resulting in inconsistent measurement units of emission limits and inconsistent test conditions between different detection means and different supervision links, which restricts the direct comparison of emission results. Therefore, a method capable of effectively converting emission results of different measurement units is needed. Summary of the Invention

[0003] The object of the present invention is to provide a method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operation modes, which solves the problems of inconsistent measurement units of emission limits and inconsistent test conditions between different detection means and different supervision links caused by different detection technical methods and emission test requirements, and further realizes the direct horizontal comparison between different emission calculation results.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operation modes, characterized in that it includes an operation mode division step:

[0006] Using the specific power of the motor vehicle, the engine load and the vehicle speed as operation condition characteristic parameters, using the specific power - vehicle speed or the engine load - vehicle speed to characterize the microscopic operation mode of the vehicle, and dividing the microscopic operation mode into multiple Bins.

[0007] Preferably, it further includes a data calculation step:

[0008] Calculating the average emission rate, average fuel consumption or average work done of pollutants in each microscopic operation mode based on the second-by-second test data.

[0009] Preferably, it further includes a working condition normalization step:

[0010] Selecting a reference working condition, and normalizing the emission results in combination with the time distribution information of each microscopic operation mode thereof.

[0011] Preferably, it further includes a unit conversion step:

[0012] Fitting the emission results of different measurement units, determining the corresponding conversion coefficients, and converting between different measurement units according to the conversion coefficients.

[0013] Preferably, by fitting the emission results of different measurement units, the conversion coefficients between ppm and g / kg-fuel, between g / kWh and g / kg-fuel, and between ppm and g / kWh are determined.

[0014] Preferably, the method is applicable to the conversion of measurement units of mobile source pollutant emission test data for motor vehicles and non-road mobile machinery.

[0015] The present invention has at least the following beneficial effects:

[0016] By dividing the microscopic operation modes, the emission characteristics of motor vehicles under different working conditions can be accurately reflected; through working condition normalization and unit conversion, the data barriers between different detection means and different supervision links are broken, and the horizontal comparison of emission calculation results composed of different emission measurement units and test working conditions is realized; it is applicable to the conversion of measurement units of mobile source pollutant emission test data including motor vehicles, non-road mobile machinery, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a schematic diagram of the correlation between ppm and g / kg-fuel, g / kWh and g / kg-fuel of the emission measurement units of heavy-duty diesel vehicles of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, and are not used to limit the present invention.

[0020] Embodiment 1

[0021] Referring to Figure 1 , a method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operation modes includes an operation mode division step, in which the vehicle specific power (VSP), engine load (Load), vehicle speed, etc. are used as operation condition characteristic parameters, and the vehicle specific power-vehicle speed (VSP-v) or engine load-vehicle speed (Load-v) is used to characterize the microscopic operation mode of the vehicle, and the microscopic operation mode is divided into multiple Bins.

[0022] It includes the following steps: Operating mode division: Using vehicle specific power (VSP), engine load (Load), vehicle speed, etc. as operating condition characteristic parameters, characterizing the microscopic operating mode of the vehicle by vehicle specific power - vehicle speed (VSP - v) or engine load - vehicle speed (Load - v), and dividing the microscopic operating mode into multiple bins; Data calculation: Calculating the average pollutant emission rate, average fuel consumption or average work done of each microscopic operating mode based on the second - by - second test data; Operating condition normalization: Selecting a reference operating condition, and combining the time distribution information of its each microscopic operating mode to normalize the emission results; Unit conversion: Fitting the emission results in different measurement units to determine the corresponding conversion coefficients, so as to achieve the conversion between different measurement units.

[0023] As can be seen from the above embodiments: Through the division of the microscopic operating mode, the emission characteristics of motor vehicles under different operating conditions can be accurately reflected; Through operating condition normalization and unit conversion, the data barriers between different detection means and different supervision links are broken, and the horizontal comparison of emission calculation results composed of different emission measurement units and test operating conditions is realized; It is applicable to the conversion of measurement units of pollutant emission test data of other mobile sources including non - road mobile machinery, etc.

[0024] Embodiment 2

[0025] Referring to Figure 1 , it also includes a data calculation step of calculating the average pollutant emission rate, average fuel consumption or average work done of each microscopic operating mode based on the second - by - second test data.

[0026] It also includes an operating condition normalization step of selecting a reference operating condition and combining the time distribution information of its each microscopic operating mode to normalize the emission results.

[0027] It also includes a unit conversion step of fitting the emission results in different measurement units to determine the corresponding conversion coefficients, so as to achieve the conversion between different measurement units.

[0028] By fitting the emission results in different measurement units, the conversion coefficients between ppm and g / kg - fuel, g / kWh and g / kg - fuel can be determined.

[0029] It is applicable to the conversion of measurement units of pollutant emission test data of mobile sources including motor vehicles and non - road mobile machinery, etc.

[0030] The present invention provides a method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes, including the following steps:

[0031] Operating mode division

[0032] The running mode division is the first step of the method of the present invention, and its purpose is to divide the actual driving conditions of a motor vehicle into multiple microscopic running modes (Bins). In the present invention, vehicle specific power (VSP), engine load (Load), vehicle speed, etc. are used as operating condition characteristic parameters, and vehicle specific power - vehicle speed (VSP - v) or engine load - vehicle speed (Load - v) is used to characterize the microscopic running modes of the vehicle.

[0033] During the running mode division process, the microscopic running modes can be divided into multiple Bins according to actual needs. For example, according to different combinations of vehicle specific power (VSP) and vehicle speed (v), the microscopic running modes can be divided into various operating condition types such as idling, accelerating, cruising, decelerating, etc.

[0034] Data calculation

[0035] In the data calculation step, the average pollutant emission rate, average fuel consumption, or average work done of each microscopic running mode is calculated based on the second - by - second test data. These data are the basis for subsequent operating condition normalization and unit conversion.

[0036] Specifically, for each microscopic running mode (Bin), according to the second - by - second test data within the Bin, the average emission rate of pollutants (such as the average emission rate of NOx), average fuel consumption (the amount of fuel consumed per unit time), or average work done (the work done by the engine per unit time) is calculated. These calculation results reflect the emission characteristics and energy consumption levels of the vehicle under this microscopic running mode.

[0037] Operating condition normalization

[0038] The purpose of the operating condition normalization step is to eliminate the influence of different test operating conditions on the emission results, so that the emission results between different regulatory means are comparable. In the present invention, a reference operating condition (such as standard operating conditions like C - WTVC or CHTC, etc.) is selected, and in combination with the time distribution information of its various microscopic running modes, the emission results are normalized for operating conditions.

[0039] Specifically, first, determine the time distribution ratio of each microscopic running mode in the reference operating condition. Then, for the emission data to be converted (from different test operating conditions), the emission data of each microscopic running mode are weighted and averaged according to the time distribution ratio of the reference operating condition, so as to obtain the emission results after operating condition normalization. The emission data processed in this way eliminates the influence of the test operating conditions, making the emission results between different regulatory means comparable.

[0040] Unit conversion

[0041] The unit conversion step is the core part of the method of the present invention, and its purpose is to achieve effective conversion between different measurement units. In the present invention, by fitting the emission results of different measurement units, the corresponding conversion coefficients are determined, so as to achieve the conversion between different measurement units.

[0042] Specifically, first, a large amount of emission data in different measurement units (such as ppm, g / kWh, g / kg-fuel, etc.) is collected. Then, using these data, the conversion relationship between different measurement units is fitted, and the corresponding conversion coefficients are determined. For example, the conversion relationship between ppm and g / kg-fuel can be fitted by methods such as linear regression, and the conversion coefficient k1 is determined; similarly, the conversion relationship between g / kWh and g / kg-fuel can be fitted, and the conversion coefficient k2 is determined. On this basis, the conversion coefficient between ppm and g / kWh can also be fitted. The emission data processed in this way can achieve effective conversion between different measurement units.

[0043] It breaks the data barriers between different detection means and different supervision links, and realizes the horizontal comparison of the emission calculation results composed of different emission measurement units and test conditions. The emission data processed by condition normalization and unit conversion eliminates the influence of test conditions and measurement units, making the emission results between different supervision means comparable.

[0044] It improves the accuracy and effectiveness of motor vehicle emission supervision. By subdividing the microscopic operation modes and calculating the emission data under each mode, the emission characteristics of motor vehicles under different working conditions can be more accurately reflected; at the same time, through unit conversion, the emission results in different measurement units can be effectively converted, making the analysis and comparison of emission data more convenient and accurate.

[0045] It is applicable to the conversion of measurement units of emission test data of mobile sources including motor vehicles and non-road mobile machinery, etc. The conversion method of the present invention is not only applicable to motor vehicles, but also can be extended to the field of conversion of measurement units of emission test data of other mobile sources such as non-road mobile machinery, and has a wide application prospect.

[0046] In order to solve the problems of inconsistent measurement units of emission limits and inconsistent test conditions between different detection means and different supervision links, the present invention proposes a method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operation modes.

[0047] Taking NO X as an example, the commonly used emission evaluation measurement units mainly include ppm, g / kWh, and g / kg-fuel, and the calculation formulas are shown in Formulas (1), (2), and (3). It can be seen that the variables for the conversion between the unit ppm and g / kg-fuel are (i.e., air-fuel ratio), the variables for the conversion between g / kg-fuel and g / kWh are BSFC (brake specific fuel consumption). The air-fuel ratio and specific fuel consumption are affected by the characteristics of vehicle operating conditions. Therefore, unit conversion can only be carried out under the same operating condition or normalized operating condition.

[0048]

[0049] g / kg-fuel:

[0050]

[0051] g / kWh:

[0052] In the formula: is the NO emission concentration directly measured by the emission analyzer, ppm; X the emission concentration, ppm; is the NO emission factor based on fuel consumption, g / kg-fuel; F X the emission factor, g / kg-fuel; F Exh. is the exhaust gas flow rate, kg / h; F air and F fuel are the intake air volume and fuel flow rate respectively, kg / h; is the specific NOX emission based on engine work, g / kWh; BSFC is the fuel consumption per unit work, g-fuel / kWh.

[0053] Step 1: In order to eliminate the influence of driving conditions on emissions, vehicle specific power (VSP), engine load (Load), vehicle speed, etc. are used as operating condition characteristic parameters, and vehicle microscopic operating modes are characterized by vehicle specific power - vehicle speed (VSP-v) or engine load - vehicle speed (Load-v). Among them, the calculation of VSP directly adopts the calculation formula proposed by the MOVES model, such as formula (4); Load is calculated from the ratio of the engine's real-time output power to the rated power, as shown in formula (5).

[0054]

[0055]

[0056] In the formula: VSP is the vehicle specific power, kW / t; a is the instantaneous acceleration, m / s 2 ; g is the acceleration due to gravity, 9.8m / s 2 ; θ is the road slope, °; v is the instantaneous speed, m / s; m is the total vehicle weight, t; A is the rolling resistance coefficient, kWs / m; B is the rotational resistance coefficient, kWs 2 / m 2 ; C is the air resistance coefficient, kWs 3 / m3 ; Load t is the engine load at time t, %; Torque t is the engine torque at time t, Nm; Speed t is the engine speed at time t, rpm; Power rated is the rated power, kW.

[0057] According to the characteristics of the actual operation of typical motor vehicles, VSP-v can usually be divided into 22 microscopic operation modes (Bins), including 1 braking condition (Bin0), 1 idling condition (Bin1) and 20 cruising or accelerating conditions (Bin11 - 38), and Load-v is divided into 19 Bins (see Tables 1 and 2). In addition, the number of Bins can also be increased or decreased according to specific requirements.

[0058] Table 1 Microscopic operation modes of VSP-v

[0059]

[0060] The braking condition is defined as the instantaneous acceleration a < -0.55 m / s 2 or the acceleration in the current instant and the previous two seconds is < -0.28 m / s 2 .

[0061] Table 2 Microscopic operation modes of Load-v

[0062]

[0063] Step 2: Based on the division of microscopic operation modes in Step 1, calculate the average pollutant emission rate, average fuel consumption or average work done in each microscopic operation mode using the second-by-second test data, as shown in formulas (6) - (8).

[0064]

[0065]

[0066]

[0067] Step 3: Select a reference condition (such as C-WTVC or CHTC, etc.), and normalize the emission results in combination with the time distribution information of each microscopic operation mode, as shown in formulas (9) and (10).

[0068]

[0069]

[0070] Step 4: Fit the emission results in different measurement units to determine the corresponding conversion coefficients.

[0071] As Figure 1 shown, after the working conditions are normalized based on VSP-v and Power-v, ppm and g / kg-fuel have a good correlation, with R 2 > 0.9 and a conversion coefficient of 14.18211. g / kWh and g / kg-fuel are also highly correlated, with a conversion coefficient BSFC (gfuel / kWh) of 228.27. In addition, the conversion coefficients of different measurement units based on speed / working condition intervals can be further fitted according to this method, so as to construct conversion coefficients for different enterprises, vehicle models / engine families, and working conditions to support the multi-source emission data fusion analysis of large samples of diesel vehicles

[0072] According to the above embodiments, the present invention provides a method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operation modes. Through steps such as operation mode division, data calculation, working condition normalization, and unit conversion, effective conversion between different measurement units is achieved, breaking the data barriers between different detection means and different supervision links, and providing strong support for the efficient supervision of motor vehicle emissions. At the same time, the present invention is not only applicable to motor vehicles, but also applicable to the conversion of measurement units of pollutant emission test data of other mobile sources such as non-road mobile machinery, and has a wide application prospect

[0073] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection required by the present invention is defined by the appended claims and their equivalents

Claims

1. A method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes, characterized in that: This involves running the modal partitioning step: The motor vehicle specific power, engine load and vehicle speed are used as characteristic parameters of the operating conditions, the motor vehicle specific power-vehicle speed or engine load-vehicle speed is used to characterize the vehicle's microscopic operating mode, and the microscopic operating mode is divided into multiple Bins.

2. The method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes according to claim 1 is characterized in that: It also includes data calculation steps: The average pollutant emission rate, average fuel consumption or average work done for each microscopic operating mode is calculated based on the second-by-second test data.

3. The method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes according to claim 1 is characterized in that: It also includes the working condition normalization step: Select a baseline operating condition and normalize the emission results based on the time distribution information of each microscopic operating mode.

4. The method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes according to claim 1 is characterized in that: A unit conversion step is also included: Fit the emission results of different measurement units, determine the corresponding conversion coefficients, and convert between different measurement units based on the conversion coefficients.

5. The method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes according to claim 4 is characterized in that: The conversion coefficients between ppm and g / kg-fuel, between g / kWh and g / kg-fuel, and between ppm and g / kWh are determined by fitting the emission results of different measurement units.

6. The method for converting different measurement units of motor vehicle exhaust emissions based on microscopic operating modes according to claim 5 is characterized in that: The method described is applicable to the conversion of measurement units of mobile source pollutant emission test data of motor vehicles and non-road mobile machinery.

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