CN116255234A - Method for monitoring SCR efficiency of in-use vehicle by using remote emission management terminal data - Google Patents

Method for monitoring SCR efficiency of in-use vehicle by using remote emission management terminal data Download PDF

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CN116255234A
CN116255234A CN202310261843.6A CN202310261843A CN116255234A CN 116255234 A CN116255234 A CN 116255234A CN 202310261843 A CN202310261843 A CN 202310261843A CN 116255234 A CN116255234 A CN 116255234A
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scr
nox
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裴毅强
刘春涛
张帆
秦静
施泰峰
李志强
吴春玲
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Tianjin University
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Tianjin University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F16/00—Information retrieval; Database structures therefor; File system structures therefor
    • G06F16/20—Information retrieval; Database structures therefor; File system structures therefor of structured data, e.g. relational data
    • G06F16/21—Design, administration or maintenance of databases
    • G06F16/215—Improving data quality; Data cleansing, e.g. de-duplication, removing invalid entries or correcting typographical errors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0416—Methods of control or diagnosing using the state of a sensor, e.g. of an exhaust gas sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1621—Catalyst conversion efficiency
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806—Properties of reducing agent or dosing system
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

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Abstract

The invention discloses a method for monitoring the SCR efficiency of an on-vehicle by utilizing remote emission management terminal data, which comprises the following steps: reading data generated by a remote emission terminal, and importing engine reference torque; data cleaning, namely, effective data extraction is completed; the invention uses the data item which is required to be uploaded by the existing diesel vehicle emission standard as a basis, does not need to add additional data items or test equipment, has zero increase of cost, can help the supervision department to increase the supervision strength and coverage area, and can help the engine manufacturer to save the cost of expensive test equipment; the method has the advantages that the SCR efficiency evaluation model is built by cleaning and processing the uploaded data, the SCR efficiency of the on-vehicle can be effectively monitored, the monitoring of the NOx emission of the on-vehicle actual road can be indirectly realized, the suspected vehicles with the exceeding NOx can be rapidly identified, and the problem tracking and the correction can be timely carried out.

Description

Method for monitoring SCR efficiency of in-use vehicle by using remote emission management terminal data
Technical Field
The invention belongs to the technical field of vehicle SCR efficiency monitoring, and particularly relates to a method for monitoring on-vehicle SCR efficiency by utilizing remote emission management terminal data.
Background
Under the condition that the requirements on the emission limit value of an engine are more and more severe worldwide, a selective catalytic reaction (Selective Catalytic Reduction, SCR) has become a conventional means for reducing the NOx emission of a diesel vehicle, in the development process of diesel products, SCR calibration is one of the most important contents, the SCR calibration process is complex, the purpose is to ensure that the products meet the regulation requirements in various types of test processes of inspection and detection, however, because the road conditions of actual roads are complex and various, the driving habits of drivers are different, the type test NOx emission of the emission detection of the diesel engine cannot completely represent the actual road NOx emission of the vehicle, and even if the NOx emission detection of a new vehicle is qualified, the SCR can be aged after the vehicle is used for a long time, and a high risk of exceeding NOx exists.
GB17691-2018 issued by 8 in 2018 (China sixth stage) sets forth clear requirements on a remote monitoring platform of a diesel vehicle, and from stage 6b, manufacturers should ensure that the vehicle is required to transmit emission data in the whole life period, and ecological environment authorities and manufacturers receive the emission data and utilize the emission data to monitor the emission of the vehicle in use.
The invention comprises the following steps:
the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for monitoring SCR efficiency of an in-vehicle using remote emission management terminal data, which solves the problems mentioned in the background art.
In order to solve the problems, the invention provides the technical scheme that:
a method for monitoring in-use SCR efficiency using remote emissions management terminal data, comprising the steps of:
s1, reading data generated by a remote emission terminal, and importing engine reference torque;
s2, removing invalid data and error data existing in the remote emission terminal data through a data cleaning unit, and completing effective data extraction;
s3, calculating by adopting a moving window method, dividing effective data of vehicle operation into continuous windows according to a time sequence, calculating conversion efficiency in each window according to NOx sensor measurement values at the upstream and downstream of the SCR, determining the size of the moving window according to a NOx mass integral value at the upstream of the SCR, and calculating primary SCR conversion efficiency when the NOx mass integral reaches a certain threshold value;
s4, judging whether the SCR efficiency is normal.
Preferably, the remote emission terminal in S1 includes a data processing unit, a data acquisition module, a data type detection module, a data classification module and a network communication module, where the data acquisition unit is used to acquire emission parameters of the automobile and send the acquired fuel ratio, fuel flow rate and driving distance to the data type detection module; the data type detection module is used for detecting the fuel type according to the emission parameters and sending the judgment result to the data classification module; the data classification module is used for distinguishing and classifying the data of different fuel types according to the judging result; the network communication module is used for establishing remote communication between the remote emission terminal and the monitoring client to realize transmission of vehicle driving data.
Preferably, the data cleaning unit in S2 includes a data extraction module, a data decoding module, an authenticity verification module, a data analysis module and a data cleaning unit, where the data extraction module is used to extract the vehicle emission parameter data summarized in the remote emission terminal and send the data to the data decoding module; the data decoding module is used for decoding the received data and sending the decoded data to the authenticity verification module; the authenticity verification module is used for verifying the authenticity of the data and sending the verified data to the data analysis module; the data analysis module is used for analyzing the data, judging the type of the data and sending the data to the data cleaning unit, and the data cleaning unit is used for cleaning the data which do not accord with detection from the system.
Preferably, the invalid data in S2 includes the following contents:
A. environmental conditions are not suitable: the combustion of the engine is deteriorated in the plateau environment, so that the SCR conversion efficiency is abnormal;
B. NOx sensor dew point detection is incomplete: according to the measured values of the NOx sensors before and after SCR, the measured values of the NOx sensors are false values before the dew point detection of the NOx sensors is completed, and cannot be used for calculating the conversion efficiency of the SCR;
C. SCR operating conditions are not suitable: according to the characteristics of the reducing agent and the SCR catalyst, the reducing agent with lower temperature participates in the reaction, or the SCR conversion efficiency is lower, and after the temperature exceeds a certain value, the SCR conversion efficiency is low, the SCR is under abnormal working condition and is not suitable for calculating the SCR efficiency;
D. the exhaust flow rate is not suitable: the unsuitable airspeed range results in a decrease in SCR conversion efficiency, and airspeed is affected by exhaust flow or intake flow, which is closely related to engine speed and torque, and the resulting data is unsuitable for SCR efficiency calculations.
Preferably, the threshold value integrated in the step S3 is normalized according to the reference torque of the machine type
The calculation formula of the threshold value of the integral is as follows: m is m lmt ＝a*T std
Wherein m is lmt A threshold value for NOx mass integration in g; t (T) std The unit is N.m for the reference torque of the engine; a is an adjustment coefficient, the unit is g/(N.m), and the value range is generally 0.05-0.1.
Preferably, in S3, the measured value of NOx is concentration, the measured value of the mass integration threshold is weight, and the calculation formula for converting the NOx concentration into the mass flow is:
mf NOx ＝c NOx *46*(mf air +mf fuel *0.835)*277.78/29/1000000000
wherein mf is NOx Mass flow in g/s for NOx; c NOx For NOx sensingMeasured values in ppm; mf (mf) air The unit is the air inlet flow rate, and the unit is kg/h; mf (mf) fuel The fuel flow is expressed as L/h.
Preferably, the frequency of the data acquisition module is 1Hz, when mf NOx Integral value exceeds m lmt Calculating the primary SCR efficiency, wherein the calculation formula is as follows:
eff SCR ＝(m NOx _ up -m NOx _ down )/m NOx _ up *100％
wherein ef is fSCR Conversion efficiency of SCR is expressed in units of; m is m NOx_up The unit is g for the mass integral of NOx at the upstream of SCR; m is m NOx_down The unit is g, which is the mass integral of NOx downstream of SCR.
Preferably, the formula for determining whether the SCR efficiency is normal in S4 is as follows:
eff SCR ≥eff norm * b, the efficiency is normal
eff SCR <eff norm * b, low efficiency
Wherein eff norm For the general conversion efficiency of SCR during normal operation, in order to prevent misjudgment, an adjusting coefficient b is added, and the value range of b is 0.75-0.85.
Preferably, in the step S4, the SCR efficiency is calculated by referring to the OBD data stream, if there is a fault related to the NOx control system, the fault may be caused by malfunction such as reactant supply, reactant quality, reactant consumption, nozzle operation, or malfunction caused by tampering, and the conversion efficiency is reduced, and such a situation should be eliminated when the SCR conversion efficiency is evaluated.
The beneficial effects of the invention are as follows:
1. the data items which are required to be uploaded by the existing diesel vehicle emission standard are used as a basis, additional data items are not required to be added, test equipment is not required to be added, the cost is zero, the supervision department can be helped to increase the supervision degree and the coverage range, and the engine manufacturer can be helped to save the cost of the expensive test equipment.
2. The method has the advantages that the SCR efficiency evaluation model is built by cleaning and processing the uploaded data, the SCR efficiency of the on-vehicle can be effectively monitored, the monitoring of the NOx emission of the on-vehicle actual road can be indirectly realized, the suspected vehicles with the exceeding NOx can be rapidly identified, and the problem tracking and the correction can be timely carried out.
Description of the drawings:
for the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
For ease of illustration, the invention is described in detail by the following detailed description and the accompanying drawings.
FIG. 1 is a schematic of the workflow of the present invention;
FIG. 2 is a schematic diagram of an evaluation of SCR inefficiency using the present method;
FIG. 3 is a schematic diagram of an evaluation of SCR inefficiency using the present method.
The specific embodiment is as follows:
as shown in fig. 1, 2 and 3, the following technical solutions are adopted in this embodiment:
example 1:
a method for monitoring in-use SCR efficiency using remote emissions management terminal data, comprising the steps of:
s1, reading data generated by a remote emission terminal, and importing engine reference torque;
s2, removing invalid data and error data existing in the remote emission terminal data through a data cleaning unit, and completing effective data extraction;
s3, calculating by adopting a moving window method, dividing effective data of vehicle operation into continuous windows according to a time sequence, calculating conversion efficiency in each window according to NOx sensor measurement values at the upstream and downstream of the SCR, determining the size of the moving window according to a NOx mass integral value at the upstream of the SCR, and calculating primary SCR conversion efficiency when the NOx mass integral reaches a certain threshold value;
s4, judging whether the SCR efficiency is normal or not;
the method has the advantages that the SCR efficiency evaluation model is built by cleaning and processing the uploaded data, the SCR efficiency of the on-vehicle can be effectively monitored, the monitoring of the NOx emission of the actual road of the on-vehicle can be indirectly realized, and for the production enterprises, the suspected vehicles with the exceeding NOx can be rapidly identified, and the problem tracking and the correction can be timely carried out; for the environmental protection department, the system can realize the emission supervision of the on-vehicle in all time periods and all regions, improve the efficiency and reduce the cost.
Example 2:
the remote emission terminal in the S1 comprises a data processing unit, a data acquisition module, a data type detection module, a data classification module and a network communication module, wherein the data acquisition unit is used for acquiring automobile emission parameters and sending acquired fuel ratio, fuel flow rate and driving distance to the data type detection module; the data type detection module is used for detecting the fuel type according to the emission parameters and sending the judgment result to the data classification module; the data classification module is used for distinguishing and classifying the data of different fuel types according to the judging result; the network communication module is used for establishing remote communication between the remote emission terminal and the monitoring client to realize transmission of vehicle driving data;
the road automobile parameters can be collected in real time, the fuel type is judged, and the automobile parameter data is classified, managed and uploaded according to the fuel type, so that the processing capacity of the front end can be improved, and the follow-up detection is convenient.
The data cleaning unit in the S2 comprises a data extraction module, a data decoding module, an authenticity verification module, a data analysis module and a data cleaning unit, wherein the data extraction module is used for extracting the summarized automobile emission parameter data in the remote emission terminal and sending the data to the data decoding module; the data decoding module is used for decoding the received data and sending the decoded data to the authenticity verification module; the authenticity verification module is used for verifying the authenticity of the data and sending the verified data to the data analysis module; the data analysis module is used for analyzing the data, judging the type of the data and sending the data to the data cleaning unit, and the data cleaning unit is used for cleaning the data which do not accord with detection from the system;
the data can be verified and managed, so that unusable data can be removed, and influence of irrelevant data or error data on a detection result is avoided.
The invalid data in S2 includes the following contents:
A. environmental conditions are not suitable: the combustion of the engine is deteriorated in the plateau environment, so that the SCR conversion efficiency is abnormal;
B. NOx sensor dew point detection is incomplete: according to the measured values of the NOx sensors before and after SCR, the measured values of the NOx sensors are false values before the dew point detection of the NOx sensors is completed, and cannot be used for calculating the conversion efficiency of the SCR;
C. SCR operating conditions are not suitable: according to the characteristics of the reducing agent and the SCR catalyst, the reducing agent with lower temperature participates in the reaction, or the SCR conversion efficiency is lower, and after the temperature exceeds a certain value, the SCR conversion efficiency is low, the SCR is under abnormal working condition and is not suitable for calculating the SCR efficiency;
D. the exhaust flow rate is not suitable: the unsuitable airspeed range results in a decrease in SCR conversion efficiency, and airspeed is affected by exhaust flow or intake flow, which is closely related to engine speed and torque, and the resulting data is unsuitable for SCR efficiency calculations.
The integral threshold in the S3 is normalized according to the reference torque of the machine type
The calculation formula of the threshold value of the integral is as follows: m is m lmt ＝a*T std
Wherein m is lmt A threshold value for NOx mass integration in g; t (T) std The unit is N.m for the reference torque of the engine; a is an adjustment coefficient, the unit is g/(N.m), and the value range is generally 0.05-0.1.
In the step S3, the measured value of the NOx is concentration, the measured value of the mass integration threshold is weight, and the calculation formula for converting the NOx concentration into the mass flow is as follows:
mf NOx ＝c NOx *46*(mf air +mf fuel *0.835)*277.78/29/1000000000
wherein mf is NOx Mass flow in g/s for NOx; c NOx Measured in ppm for a NOx sensor; mf (mf) air The unit is the air inlet flow rate, and the unit is kg/h; mf (mf) fuel The fuel flow is expressed as L/h.
The frequency of the data acquisition module is 1Hz, and when mf NOx Integral value exceedsm lmt Calculating the primary SCR efficiency, wherein the calculation formula is as follows:
eff SCR ＝(m NOx _ up -m NOx _ down )/m NOx _ up *100％
wherein ef is fSCR Conversion efficiency of SCR is expressed in units of; m is m NOx_up The unit is g for the mass integral of NOx at the upstream of SCR; m is m NOx_down The unit is g, which is the mass integral of NOx downstream of SCR.
The formula for judging whether the SCR efficiency is normal in S4 is as follows:
eff SCR ≥eff norm * b, the efficiency is normal
eff SCR <eff norm * b, low efficiency
Wherein eff norm For the general conversion efficiency of SCR during normal operation, in order to prevent misjudgment, an adjusting coefficient b is added, and the value range of b is 0.75-0.85;
in the step S4, when the SCR efficiency is calculated, the OBD data stream should be referred to, if there is a related failure of the NOx control system, specifically including failures in terms of reactant supply, reactant quality, reactant consumption, nozzle operation, failure caused by tampering, etc., the SCR may malfunction, resulting in a decrease in conversion efficiency, and such conditions should be excluded when the SCR conversion efficiency is evaluated.
Example 3:
the method comprises the steps that an automobile emission parameter is collected through a data collection unit, the collected fuel ratio, fuel flow rate and driving distance are sent to a data type detection module, the data type detection module detects the fuel type according to the emission parameter, and a judgment result is sent to a data classification module; the data classification module classifies the data of different fuel types according to the judging result; the network communication module establishes remote communication between the remote emission terminal and the monitoring client to realize the transmission of vehicle driving data, extracts summarized automobile emission parameter data in the remote emission terminal through the data extraction module, and sends the data to the data decoding module; the data decoding module decodes the received data and sends the decoded data to the authenticity verification module; authentication and verificationThe module verifies the authenticity of the data and sends the verified data to the data analysis module; the data analysis module analyzes the data, judges the type of the data and sends the data to the data cleaning unit, and the data cleaning unit cleans the data which does not accord with detection from the system, wherein the data which does not accord with detection is divided into unsuitable environmental conditions, unfinished dew point detection of the NOx sensor, unsuitable SCR working conditions and unsuitable exhaust flow; the environmental conditions are not suitable for the condition that the combustion of the engine possibly worsens in the plateau environment, so that the SCR conversion efficiency is abnormal, and therefore, the evaluation of the SCR conversion efficiency is not carried out in the plateau environment, which accords with the requirement of the GB17691-2018 standard on the condition that the OBD is suspended in a state that the altitude is higher than 2400m, and the atmospheric pressure is in certain connection with the altitude, so that the atmospheric pressure data items of the remote emission terminal can be used for screening; the method for evaluating the SCR conversion efficiency mainly comprises the steps that the dew point detection of the NOx sensor is incomplete, the measuring value of the NOx sensor is false before the dew point detection of the NOx sensor is completed, and the method cannot be used for calculating the SCR conversion efficiency. Whether the dew point detection is finished or not, and screening can be carried out by using data items of the output value of the SCR upstream NOx sensor and the output value of the SCR downstream NOx sensor of the remote emission terminal; the SCR working condition is unsuitable, according to the characteristics of a reducing agent and an SCR catalyst, when the temperature is low, the reducing agent may not participate in the reaction, or the SCR conversion efficiency is low, and after the temperature exceeds a certain value, the DPF regeneration process is likely to be entered, the SCR conversion efficiency is also low, the SCR is under abnormal working condition, the calculation of the SCR efficiency is unsuitable, whether the SCR working environment is suitable or not is judged, and the data items of the SCR inlet temperature and the SCR outlet temperature of a remote emission terminal can be used for screening; the exhaust flow is unsuitable, the airspeed is an important influencing factor of the SCR conversion efficiency, the unsuitable airspeed range may cause the reduction of the SCR conversion efficiency, and the airspeed is influenced by the exhaust flow or the intake flow, which has a close relationship with the engine speed and the torque, so that the exhaust flow can be screened by using the data items of the engine net output torque and the engine speed of the remote emission terminal; calculating by using a moving window method, and dividing effective data of vehicle operation according to a time sequenceDividing into continuous windows, calculating conversion efficiency in each window according to NOx sensor measurement values at the upstream and downstream of SCR, determining the size of the moving window according to NOx mass integral value at the upstream of SCR, calculating SCR conversion efficiency once when the NOx mass integral reaches a certain threshold value, and calculating the conversion efficiency of the SCR according to a formula m lmt ＝a*T std Normalizing the integral threshold value by reference model reference torque, and passing mf NOx ＝c NOx *46*(mf air +mf fuel *0.835 277.78/29/1000000000, converting the NOx concentration into mass flow, referring to OBD data stream to determine whether SCR efficiency is normal, if yes SCR ≥eff norm * b, if the SCR efficiency is normal, as shown in FIG. 2, if the judgment result is eff SCR <eff norm * b indicates that the SCR efficiency is low, as shown in fig. 3.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (9)

1. A method for monitoring in-use SCR efficiency using remote emissions management terminal data, comprising the steps of:
s1, reading data generated by a remote emission terminal, and importing engine reference torque;
s2, removing invalid data and error data existing in the remote emission terminal data through a data cleaning unit, and completing effective data extraction;
s3, calculating by adopting a moving window method, dividing effective data of vehicle operation into continuous windows according to a time sequence, calculating conversion efficiency in each window according to NOx sensor measurement values at the upstream and downstream of the SCR, determining the size of the moving window according to a NOx mass integral value at the upstream of the SCR, and calculating primary SCR conversion efficiency when the NOx mass integral reaches a certain threshold value;
s4, judging whether the SCR efficiency is normal.
2. The method for monitoring the SCR efficiency of an in-vehicle using the remote emission management terminal according to claim 1, wherein the remote emission management terminal in S1 comprises a data processing unit, a data acquisition module, a data type detection module, a data classification module and a network communication module, wherein the data acquisition unit is used for acquiring the emission parameters of the vehicle and transmitting the acquired fuel ratio, fuel flow rate and driving distance to the data type detection module; the data type detection module is used for detecting the fuel type according to the emission parameters and sending the judgment result to the data classification module; the data classification module is used for distinguishing and classifying the data of different fuel types according to the judging result; the network communication module is used for establishing remote communication between the remote emission terminal and the monitoring client to realize transmission of vehicle driving data.
3. The method for monitoring the SCR efficiency of an in-vehicle using the remote emission management terminal data according to claim 1, wherein the data cleaning unit in S2 comprises a data extraction module, a data decoding module, an authenticity verification module, a data analysis module and a data cleaning unit, wherein the data extraction module is used for extracting the summarized automobile emission parameter data in the remote emission terminal and transmitting the data to the data decoding module; the data decoding module is used for decoding the received data and sending the decoded data to the authenticity verification module; the authenticity verification module is used for verifying the authenticity of the data and sending the verified data to the data analysis module; the data analysis module is used for analyzing the data, judging the type of the data and sending the data to the data cleaning unit, and the data cleaning unit is used for cleaning the data which do not accord with detection from the system.
4. The method for monitoring in-vehicle SCR efficiency with remote emission management terminal data as recited in claim 1, wherein said invalidation data in S2 comprises the following:
A. environmental conditions are not suitable: the combustion of the engine is deteriorated in the plateau environment, so that the SCR conversion efficiency is abnormal;
B. NOx sensor dew point detection is incomplete: according to the measured values of the NOx sensors before and after SCR, the measured values of the NOx sensors are false values before the dew point detection of the NOx sensors is completed, and cannot be used for calculating the conversion efficiency of the SCR;
C. SCR operating conditions are not suitable: according to the characteristics of the reducing agent and the SCR catalyst, the reducing agent with lower temperature participates in the reaction, or the SCR conversion efficiency is lower, and after the temperature exceeds a certain value, the SCR conversion efficiency is low, the SCR is under abnormal working condition and is not suitable for calculating the SCR efficiency;
D. the exhaust flow rate is not suitable: the unsuitable airspeed range results in a decrease in SCR conversion efficiency, and airspeed is affected by exhaust flow or intake flow, which is closely related to engine speed and torque, and the resulting data is unsuitable for SCR efficiency calculations.
5. The method for monitoring the SCR efficiency of an in-vehicle using remote emission management terminal data as defined in claim 1, wherein the threshold integrated in S3 is normalized according to the reference torque of the model:
the calculation formula of the threshold value of the integral is as follows: m is m lmt ＝a*T std
Wherein m is lmt A threshold value for NOx mass integration in g; t (T) std The unit is N.m for the reference torque of the engine; a is an adjustment coefficient, the unit is g/(N.m), and the value range is generally 0.05-0.1.
6. The method for monitoring in-vehicle SCR efficiency with remote emission management terminal data as defined in claim 1, wherein the measured NOx value in S3 is concentration and the measured value of the mass integration threshold is weight, and the calculation formula of converting the NOx concentration into the mass flow is:
mf NOx ＝c NOx *46*(mf air +mf fuel *0.835)*277.78/29/1000000000
wherein mf is NOx Mass flow in g/s for NOx; c NOx Measured in ppm for a NOx sensor; mf (mf) air The unit is the air inlet flow rate, and the unit is kg/h; mf (mf) fuel The fuel flow is expressed as L/h.
7. The method for monitoring in-vehicle SCR efficiency with remote emissions management terminal data as defined in claim 2, wherein said data acquisition module has a frequency of 1Hz when mf NOx Integral value exceeds m lmt Calculating the primary SCR efficiency, wherein the calculation formula is as follows:
eff SCR ＝(m NOx _ up -m NOx _ down )/m NOx _ up *100％
wherein ef is fSCR Conversion efficiency of SCR is expressed in units of; m is m NOx_up The unit is g for the mass integral of NOx at the upstream of SCR; m is m NOx_down The unit is g, which is the mass integral of NOx downstream of SCR.
8. The method for monitoring SCR efficiency of in-vehicle using remote emission management terminal data as defined in claim 1, wherein the formula for determining whether SCR efficiency is normal in S4 is:
eff SCR ≥eff norm * b, the efficiency is normal
eff SCR <eff norm * b, low efficiency
Wherein eff norm For the general conversion efficiency of SCR during normal operation, in order to prevent misjudgment, an adjusting coefficient b is added, and the value range of b is 0.75-0.85.
9. The method for monitoring SCR efficiency of in-vehicle using remote emission management terminal data according to claim 1, wherein the SCR efficiency is calculated in S4 by referring to OBD data flow, if there is related malfunction of NOx control system, specifically including malfunction in terms of reagent supply, reagent quality, reagent consumption, nozzle operation, malfunction due to tampering, etc., malfunction of SCR may be caused, degradation of conversion efficiency may be caused, and such condition should be excluded when evaluating SCR conversion efficiency.
CN202310261843.6A 2023-03-17 2023-03-17 Method for monitoring SCR efficiency of in-use vehicle by using remote emission management terminal data Pending CN116255234A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117235453A (en) * 2023-11-09 2023-12-15 天津大学 Remote monitoring data restoration method and system for heavy diesel vehicle based on machine learning

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117235453A (en) * 2023-11-09 2023-12-15 天津大学 Remote monitoring data restoration method and system for heavy diesel vehicle based on machine learning
CN117235453B (en) * 2023-11-09 2024-01-26 天津大学 Remote monitoring data restoration method and system for heavy diesel vehicle based on machine learning

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