CN110671178B - A diagnostic method of exhaust temperature sensor based on exhaust temperature characteristics of different torque segments - Google Patents
A diagnostic method of exhaust temperature sensor based on exhaust temperature characteristics of different torque segments Download PDFInfo
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
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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
- F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
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- 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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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Chemical Kinetics & Catalysis (AREA)
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Abstract
一种基于不同扭矩段排温特征的排温传感器诊断方法，包括（1）通过OBD远程监管终端采集目标车辆的相关参数并上传至平台；（2）平台将诊断模块的参数配置为数据库中已有该类车辆的诊断特征参数，标时间标准比率RTL和诊断特征扭矩Tn；（3）在热机运行时间超过标定限值后，诊断模块统计排气温度超过标定温度的数据时间及与总时间占比RT；（4）将RT和RTL进行比较；（5）对于不同的扭矩段将产生不同的扭矩段时间占比Rn，将Rn值和RTL比对；（6）做出排气温度传感器信号不合理的判断结果。本发明可有效识别由于温度传感器垫高或完全拔出使得传感器测量温度显著低于实际排气温度的作弊行为，使得在用车SCR系统的非正常工作状态能够被有效识别。
An exhaust temperature sensor diagnosis method based on exhaust temperature characteristics of different torque segments, comprising (1) collecting relevant parameters of a target vehicle through an OBD remote supervision terminal and uploading them to a platform; (2) the platform configures the parameters of the diagnosis module as the parameters already in the database. There are diagnostic characteristic parameters of this type of vehicle, the standard ratio of the calibration time R TL and the diagnostic characteristic torque T n ; (3) After the running time of the thermal engine exceeds the calibration limit, the diagnostic module counts the data time of the exhaust gas temperature exceeding the calibration temperature and the total time. Time ratio R T ; (4) Compare RT and R TL ; (5) Different torque segment time ratio R n will be generated for different torque segments, and compare R n value with R TL ; (6) ) to make a judgment result that the exhaust temperature sensor signal is unreasonable. The invention can effectively identify the cheating behavior that the temperature sensor measured temperature is significantly lower than the actual exhaust gas temperature because the temperature sensor is raised or completely pulled out, so that the abnormal working state of the SCR system of the vehicle in use can be effectively identified.
Description
Technical Field
The invention relates to a method for diagnosing a heat exhaust sensor based on heat exhaust characteristics of different torque sections, belonging to the technical field of motor vehicle emission control.
Background
The exhaust gas of the engine contains harmful substances (NO for short) such as nitrogen oxidesx) The main components of which are NO and NO2。NOxIs N in air sucked into cylinder by engine2And O2Reaction products at elevated temperatures. National emission regulations on NOxAnd define limits of different degrees, the vehicles exceeding the respective limits being required to produce necessary and differentiated reaction actions in order to control NOxThe purpose of discharging.
The SCR technology is a selective catalytic reduction technology and is used for controlling NO by an enginexThe main technologies for emissions, the most common forms of which are: the ammonia gas is generated by decomposing the urea aqueous solution, and the ammonia gas and NO are reacted under the action of an SCR (selective catalytic reduction) catalystxThe selective catalytic reduction reaction is carried out to generate nitrogen and water which are then discharged into the atmosphere, and different urea amounts are sprayed into the exhaust gas of the diesel engine to carry out NO treatmentxThe discharge amount of the fuel is effectively controlled.
The most common SCR system currently on the market is the Urea-SCR system, as shown in fig. 1. Urea-SCR system uses Adblue as a reductant to reduce NO in exhaust gasxMainly comprises an SCR catalyst, a urea mixer, a urea pump, a urea nozzle, a urea tank assembly, an SCR control unit (DCU), an upstream temperature sensor of the SCR catalyst, a downstream temperature sensor of the SCR catalyst and an upstream NO of the SCR catalystxConcentration sensor, SCR catalyst downstream NOxA concentration sensor, a urea liquid level sensor, a urea temperature sensor, a urea quality sensor and the like. In the figure, long wide arrows indicate the reducing agent flow direction, short wide arrows indicate the exhaust gas flow direction, and thin solid arrows indicate the signal direction.
When the SCR system works, an SCR control unit (DCU) reads the rotating speed, the torque, the fuel injection quantity, the cooling water temperature, the supercharging pressure, the air inlet temperature, the exhaust temperature and NO from a CAN busxUpstream NO measured by sensorxThe mass of the reducing agent required by the system is calculated by taking the calculated mass flow of the exhaust gas, the thermodynamic state of the SCR system and the like as input conditions of a control algorithm according to signals such as concentration (or upstream NOx concentration estimated by a NOx primary emission model) and the like, and the corresponding reducing agent is accurately injected into actuating mechanisms such as a urea pump, a urea nozzle and the like through the DCU control. The exhaust gas temperature sensor measures as the most important switching signal for urea injection.
Since the SCR system needs to be in a certain temperature window to effectively perform catalytic conversion, the SCR temperature needs to be indicated by a temperature sensor installed at the upstream or downstream of the SCR system to control the injection timing of urea in the system. In view of this characteristic of SCR systems, there are currently some cheating methods on the vehicle market for temperature sensors: if the temperature sensor is lifted or pulled out, the measured temperature is lower than the temperature required by the normal work of the SCR system in most of time, so that urea injection is avoided, and the aim of reducing the operation cost is fulfilled.
The OBD remote supervision terminal (hereinafter referred to as terminal) is usually installed on a vehicle OBD diagnosis interface, can acquire main operation parameters (such as rotating speed, air inlet mass flow, fuel consumption rate, net output torque of an engine, SCR inlet temperature, SCR outlet temperature, urea injection amount, urea liquid level sensor signals, downstream NOx sensor measurement values and the like) of a vehicle in the operation process, and sends data to a motor vehicle emission remote supervision platform (hereinafter referred to as platform) according to a formulated format through a 4G module of the terminal.
The motor vehicle emission remote supervision platform can receive data uploaded by terminals installed on different vehicles, and carries out a series of operations such as collection, processing, storage, calculation, display and management on the data uploaded by the vehicle-mounted terminals so as to realize corresponding supervision service functions.
Disclosure of Invention
The invention aims to provide a method for diagnosing a temperature exhaust sensor based on different torque section temperature exhaust characteristics, which aims to identify and solve possible cheating behaviors of the exhaust temperature sensor in the use process of a diesel vehicle.
The technical scheme of the invention is that the method for diagnosing the exhaust temperature sensor based on the exhaust temperature characteristics of different torque sections comprises the steps of acquiring dynamic operation data and static data of an engine at a frequency of at least 1Hz through a terminal, and uploading the dynamic operation data and the static data to a remote monitoring platform (hereinafter referred to as a platform) for motor vehicle exhaust through the terminal; the platform inputs the dynamic operation data uploaded by the vehicle into a corresponding diagnosis module to carry out signal diagnosis; and judging whether the temperature signal is reasonable or not by comparing the exhaust temperature distribution characteristics of the current vehicle with the exhaust temperature distribution characteristics of the vehicles in the database.
A method for diagnosing a temperature exhaust sensor based on temperature exhaust characteristics of different torque sections comprises the following steps:
(1) and acquiring related dynamic operation parameters of signal diagnosis of the target vehicle and the exhaust temperature sensor and static parameters of vehicle registration information through an OBD remote monitoring terminal and uploading the parameters to a platform.
(2) After the platform receives the data uploaded by the terminal, the parameters of the diagnosis module are configured into diagnosis characteristic parameters of the existing vehicles in the database through the identification of the static parameter part of the data, and the characteristic parameters comprise standard ratio of standard time for reaching the exhaust temperature (according to the standard ratio)Calibration to obtain) RTLAnd diagnosing the characteristic torque Tn(model calibration phase and RTLClosest torque segment time ratio RnThe corresponding torque).
(3) The characteristic parameters of the vehicle diagnosis module are determined after the data calibration of real vehicle test data or the data calibration of at least 5 similar vehicles on the platform.
(4) The diagnostic module firstly puts SCR upstream/downstream exhaust temperature data with the same time stamp into module input according to torque information, counts data time when the exhaust temperature in the module exceeds a calibration temperature (generally set to be about 200 ℃) after the exhaust temperature data in the module is accumulated for a certain time (a heat engine running time limit value), and calculates an exhaust temperature standard time ratio RTAnd R isTAnd an exhaust temperature on-time standard ratio R in the diagnostic moduleTLAnd (6) comparison.
(5) For each vehicle type diagnostic module, different torque segments thereof have different time distribution ratios R after the same heat engine operation time in step (4)nUsing exhaust temperature standard ratio RTLSubtracting the measured time distribution ratio RnTo obtain Un；
(6) When the output result of the diagnosis module is considered to be stable and reliable after a period of heat engine running time which is long enough, the exhaust temperature is subjected to the standard ratio R of the time reaching the standardTLAnd the time ratio R of the torque higher than the diagnostic characteristic torque by one stepn+1Comparing results, and obtaining a final result of the rationality judgment of the exhaust temperature sensor by combining the comparison result in the step (4); if R isT<RTLAnd U isn+1<0, the temperature sensor has cheating behavior.
The engine dynamic operating data includes net engine output torque, friction torque, accelerator pedal opening, specific fuel consumption, engine speed, vehicle speed, SCR upstream or downstream temperature sensor measurement, engine run time, and coolant temperature.
The target vehicle must be equipped with an OBD remote supervisory terminal, and the data that the terminal can upload through the OBD interface at least comprises engine speed, SCR upstream temperature sensor measurement or SCR downstream sensor measurement, engine net output torque.
The OBD remote monitoring terminal has to upload data to a unified platform, and the platform diagnoses the exhaust temperature sensor signal through a calibrated diagnosis module.
The running time of the heat engine of the target vehicle must exceed the heat engine running calibration limit, and the data quantity uploaded to the platform can ensure the validity of the diagnosis result.
The calculated exhaust temperature attainment time ratio RTIn time, the correction of the calibration temperature needs to be performed depending on the ambient temperature of the vehicle.
The diagnostic characteristic parameters of the vehicle of the type are calibrated, and the calibration is realized by two methods, one method is as follows: calibrating the diagnosis module by obtaining corresponding data through real vehicle measurement in a normal state; the second step is as follows: and performing data screening and feature extraction through the existing similar vehicle data of the platform, and calibrating the diagnosis module.
The method has the advantages that the method can effectively identify the cheating behavior that the temperature measured by the sensor is obviously lower than the actual exhaust temperature due to the fact that the temperature sensor is raised (partially pulled out) or completely pulled out, so that the abnormal working state of the SCR system of the in-use vehicle can be effectively identified, the cheating behavior can be effectively restrained through the accurate supervision of an environmental protection department, and the method makes a substantial contribution to the reduction of the NOx emission of the in-use diesel vehicle.
Drawings
FIG. 1 is a schematic structural diagram of a conventional Urea-SCR system;
FIG. 2 is a working schematic diagram of an OBD remote supervisory system;
FIG. 3 is a flow chart of an exhaust temperature sensor signal rationality diagnostic;
FIG. 4 is a schematic diagram of a characteristic torque calibration method of the exhaust temperature sensor diagnostic module;
FIG. 5 is a schematic illustration of a particular method of diagnosing an exhaust temperature sensor based on exhaust temperature profile characteristics for different torque segments.
Detailed Description
The working principle diagram of the OBD remote supervisory system of the present embodiment is shown in fig. 2.
The OBD remote supervision terminal is usually installed on an OBD diagnosis interface of a vehicle, CAN acquire main operation parameters (such as engine rotating speed, air inlet mass flow, fuel consumption rate, net engine output torque, SCR inlet temperature/SCR outlet temperature, urea injection amount, urea liquid level sensor signals, downstream NOx sensor measurement values and the like) of the vehicle in the operation process through a CAN bus, and sends data to a motor vehicle emission remote supervision platform according to a formulated format through a 4G module of the terminal. The platform can receive data uploaded by terminals installed on different vehicles, and perform a series of operations such as data preprocessing, storage and calculation to realize corresponding functions. The diagnosis method is realized by combining a platform with a plurality of vehicle big data.
The flow of diagnosing the rationality of the exhaust gas temperature sensor signal in the present embodiment is shown in fig. 3.
Firstly, relevant parameters of a target vehicle are collected through an OBD remote supervision terminal and uploaded to a platform, and the platform configures the parameters of a diagnosis module into diagnosis characteristic parameters (including exhaust temperature standard time ratio R) of the existing vehicle in a databaseTLAnd diagnosing the characteristic torque Tqn). When the running time of the heat engine of the target vehicle exceeds a calibration limit value, the diagnosis module counts the data time of the exhaust temperature exceeding the calibration temperature and the ratio R of the data time to the total timeTSimultaneously adding RTAnd RTLA comparison is made. Different torque segment time ratios R will be generated for different torque segmentsnR is to benValue and RTLComparison, if R isTLess than Rn+1And R isTLess than RTLAnd making a judgment result that the signal of the exhaust temperature sensor is unreasonable.
The diagnostic feature torque calibration method of the exhaust gas temperature sensor diagnostic module of the present embodiment is shown in FIG. 4.
Firstly, selecting a vehicle with normal vehicle condition and normal exhaust temperature sensor performance for data acquisition aiming at a target vehicle type, and acquiring data such as net output torque (%) of an engine, fuel consumption rate, exhaust temperature, engine speed, cooling water temperature and the like through a terminal device connected with an OBD interface of the vehicle.
After the engine is started, the temperature of cooling water of the engine is monitored, and once the temperature of the cooling water is monitored to exceed 80 ℃, a heat engine working time counter of the engine starts to work to count the total running time of the engine after heat engine.
After data are continuously collected for a long time, the net output torque after the engine is heated is respectively counted>20%，>30%，>40%，>50%，>60%，>70%，>80% of the time, and dividing the corresponding time by the total running time after the heat engine to obtain the time distribution conditions of different torque sections, and recording the time ratio (respectively recorded as R) of each torque section2，R3，R4，R5，R6，R7，R8）。
Meanwhile, counting the time when the signal value of the SCR upstream or downstream temperature sensor is greater than the time of the calibration temperature (such as 200 ℃) after the engine heat engine in the same total heat engine running time, and defining the ratio of the time to the total heat engine time as the exhaust temperature standard time ratio RT) And the value of this ratio is recorded.
Selection and exhaust temperature standard ratio RTLThe torque corresponding to the closest torque segment time ratio is the diagnostic characteristic torque of the module.
The method of diagnosing the exhaust gas temperature sensor based on the exhaust temperature distribution characteristics of different torque segments according to the present embodiment is shown in fig. 5.
After a vehicle engine provided with an OBD remote monitoring terminal is started, the platform monitors the cooling water temperature of the engine through data uploaded by the terminal, and once the temperature of the cooling water is monitored to exceed 80 ℃, a heat engine working time counter of the engine starts to work for counting the total running time of the engine after the heat engine.
After the platform receives the data uploaded by the terminal, the platform identifies the static parameter part of the data to diagnoseThe parameter configuration of the interrupt module is selected from the diagnostic characteristic value of the existing vehicle and the standard ratio (obtained according to calibration) R of the standard time for reaching the post-processing temperature of the existing vehicle in the databaseTLClosest torque segment time ratio RnThe corresponding torque is the diagnostic characteristic torque of the module. RTLAnd TqnI.e. characteristic parameters of the diagnostic module.
After a period of data acquisition time which is long enough, respectively counting the net output torque after the engine is heated>20%，>30%，>40%，>50%，>60%，>70%，>80% of the time; dividing the corresponding time with the total running time after the heat engine to obtain the time distribution conditions of different torque sections, and recording the time ratio (respectively marked as R) of each torque section2，R3，R4，R5，R6，R7，R8）。
Meanwhile, in the same total operation time of the heat engine, counting the time that the signal value of the SCR upstream or downstream temperature sensor is greater than 200 ℃ after the heat engine of the engine, namely the actual standard time ratio R of the aftertreatment temperatureT。RTAnd the time ratio R of the corresponding torque segmentsnIs recorded as UnAssuming that the characteristic torque of the vehicle type is 50%, R is calculatedTAnd a time ratio R of greater than 60% torque segment6Difference value U of6(ii) a If U is present6<0, while R isT<RTLIt is assumed that the temperature sensor may have a cheating behavior.
Claims (8)
1. A temperature exhaust sensor diagnosis method based on different torque section temperature exhaust characteristics is characterized in that dynamic operation data and static data of an engine are collected through a terminal at a frequency of at least 1Hz and uploaded to a motor vehicle emission remote supervision platform through the terminal; the motor vehicle emission remote supervision platform inputs dynamic operation data uploaded by the vehicle into a corresponding diagnosis module for signal diagnosis; judging whether the temperature signal is reasonable or not by comparing the exhaust temperature distribution characteristics of the current vehicle with the exhaust temperature distribution characteristics of the vehicles in the database;
the method comprises the following steps:
(1) acquiring related dynamic operating parameters and vehicle registration information static parameters of signal diagnosis of a target vehicle and an exhaust temperature sensor through an OBD remote monitoring terminal and uploading the parameters to a motor vehicle emission remote monitoring platform;
(2) after receiving the data uploaded by the terminal, the motor vehicle emission remote supervision platform configures the parameters of the diagnosis module into diagnosis characteristic parameters of the existing vehicles in the database through the identification of the static parameter part of the data, wherein the characteristic parameters comprise an exhaust temperature standard reaching time ratio RTL and a diagnosis characteristic torque Tn;
(3) the characteristic parameters of the diagnosis module are determined after being calibrated by real vehicle test data or data of at least 5 similar vehicles of a motor vehicle emission remote supervision platform;
(4) the diagnostic module firstly puts SCR upstream/downstream exhaust temperature data with the same timestamp into module input according to torque information, counts data time when the exhaust temperature exceeds a calibration temperature after the exhaust temperature data in the module is accumulated for a certain time, calculates an exhaust temperature standard time ratio RT according to the data time, and compares the RT with an exhaust temperature standard time ratio RTL in the diagnostic module;
(5) for each vehicle type diagnosis module, after the same heat engine operation time in the step (4), different torque sections have different time distribution ratios Rn, and Un is obtained by subtracting the measured time distribution ratios Rn from the exhaust temperature standard time ratio RTL;
(6) after a period of heat engine running time which is long enough, the output result of the diagnosis module is considered to be stable and credible, at the moment, the result of the time ratio Rn +1 of the standard ratio RTL of the exhaust temperature reaching time and the torque of which the diagnosis characteristic torque is higher by one level is compared, and the final result of the rationality judgment of the exhaust temperature sensor is obtained by combining the comparison result in the step (4); if RT < RTL and Un +1<0, then there is cheating behavior by the temperature sensor.
2. The exhaust temperature sensor diagnosis method based on exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the target vehicle is required to be equipped with an OBD remote supervision terminal, and the data which can be uploaded by the terminal through an OBD interface at least comprises engine speed, SCR upstream temperature sensor measurement value or SCR downstream sensor measurement value, and engine net output torque.
3. The exhaust temperature sensor diagnosis method based on the exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the OBD remote monitoring terminal has to upload data to a unified vehicle emission remote supervision platform, and the vehicle emission remote supervision platform diagnoses the exhaust temperature sensor signals through a calibrated diagnosis module.
4. The exhaust temperature sensor diagnosis method based on the exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the target vehicle thermal engine operation time must exceed a thermal engine operation calibration limit, and the data volume uploaded to the vehicle emission remote supervision platform can ensure the validity of the diagnosis result.
5. The exhaust temperature sensor diagnosis method based on exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the correction of the calibration temperature when calculating the exhaust temperature reaching time ratio RT needs to be corrected depending on the ambient temperature of the vehicle operation.
6. The exhaust temperature sensor diagnosis method based on the exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the diagnosis characteristic parameters of the vehicle are calibrated, and the calibration is realized by one of two methods: calibrating the diagnosis module by obtaining corresponding data through real vehicle measurement in a normal state; the second step is as follows: and performing data screening and feature extraction through the existing similar vehicle data of the motor vehicle emission remote monitoring platform, and calibrating the diagnosis module.
7. The exhaust temperature sensor diagnostic method based on exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the diagnostic module has a large amount of historical data or real vehicle calibration data of each type of vehicle, including exhaust temperature distribution characteristics within a certain torque range.
8. The exhaust temperature sensor diagnosis method based on the exhaust temperature characteristics of different torque sections as claimed in claim 1, wherein the diagnostic characteristic torque Tn is a torque corresponding to a torque section time ratio Rn closest to RTL in a calibration stage of a diagnostic module.
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| CN111636955B (en) * | 2020-06-08 | 2021-12-21 | 安徽华菱汽车有限公司 | Heavy diesel vehicle and engine aftertreatment anti-cheating method and system thereof |
| CN114060132B (en) * | 2021-11-08 | 2022-10-25 | 同济大学 | A NOx sensor cheating detection method based on remote monitoring of emissions |
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| CN109799093A (en) * | 2019-01-21 | 2019-05-24 | 合肥维克杰信息科技有限公司 | A kind of vehicle mounted tail gas discharge diagnosing remote monitoring method and monitor terminal |
| CN109981742A (en) * | 2019-02-26 | 2019-07-05 | 武汉理工大学 | Ship machine emissions data and ship equipment on-line monitoring system and method |
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