• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A method for monitoring nitrogen oxide detectors (5, 6) of an exhaust after-treatment system (1, 10) of a motor vehicle comprising an SCR catalyst (4). According to the method the NOx nitrogen oxide detector signal downstream of the SCR catalyst (4) is compared to a NOx value upstream of the SCR catalyst (4), before the SCR catalyst (4) exceeds a threshold temperature (Tth).
    公开号:FR3046813A1
    申请号:FR1750401
    申请日:2017-01-19
    公开日:2017-07-21
    发明作者:Tobias Pfister；Torsten Handler
    申请人:Robert Bosch GmbH；
    IPC主号:
    专利说明:

    Field of the invention
    The present invention relates to a method of monitoring NOx nitrogen oxide detectors installed in an exhaust aftertreatment system of a motor vehicle. The invention also relates to a computer program executing the steps of the method when the program is applied by a computer, as well as a machine-readable memory medium containing the recording of the program.
    Finally, the subject of the invention is an electronic control apparatus for implementing the method.
    State of the art
    Increasingly stringent limit values for nitrogen oxides NOx emissions have led to the development of a wide range of exhaust aftertreatment techniques to control the NOx emissions of nitrogen oxides contained in exhaust gas from a diesel engine. One of these exhaust aftertreatment techniques is the selective catalytic reduction carried out in an SCR catalyst. This process reduces the nitrogen oxides of the exhaust gas at the SCR catalyst with ammonia to give nitrogen (N2).
    The components of the exhaust gas, for example SCR catalysts, are monitored with other NOx nitrogen oxide sensors currently used. The regulation prescribes both the monitoring of catalysts and also the very precise diagnosis of the detectors. In particular, NOx nitrogen oxide detectors installed upstream of an SCR catalyst or of a catalyst NSC (NOx nitrogen oxide storage catalyst), these catalysts belonging to nitrogen oxide detectors. NOx which are very difficult to monitor because they are exposed to cleaned exhaust gases so that the emissions and the measurement signal are very low.
    According to the document DE 10 2013 203 578 A1 there is known a method for monitoring an exhaust gas aftertreatment system comprising at least a first SCR catalyst and a second SCR catalyst in the direction of passage of the exhaust gases. . This document describes the operating phase during which the operating temperature of the second SCR catalyst is sufficiently low that there is practically no reduction of NOx nitrogen oxides in this SCR catalyst, to conclude on the basis of on the signals of a NOx nitrogen oxide detector downstream of the second catalyst unit, the operation of the first SCR catalyst unit.
    Description and advantages of the invention
    The subject of the present invention is a method for monitoring a nitrogen oxide detector of an exhaust gas post-treatment system of a motor vehicle comprising at least one SCR catalyst, this process being characterized in that the signal of the nitrogen oxide detector NOx downstream of the SCR catalyst is compared with a value of NOx upstream of the SCR catalyst, before the SCR catalyst exceeds a temperature threshold.
    The predefined temperature threshold is in particular the trigger temperature, that is to say the temperature from which the catalyst (s) become active and that there is thus a conversion of NOx nitrogen oxides to nitrogen. Comparing the values (levels) of NOx nitrogen oxides downstream and upstream of the SCR catalyst before reaching the triggering temperature, is very advantageous, since in this phase, the effect of the reduction of nitrogen oxides NOx by the SCR catalyst does not appear yet. In this phase, the NOx nitrogen oxide detectors, intact, upstream and downstream of the SCR catalyst give the same value of NOx nitrogen oxides and the behaviors are identical from the dynamic point of view. If the levels of NOX nitrogen oxides differ, it can be concluded that there is a defect.
    Preferably, the signal provided by the NOx nitrogen oxide detector installed downstream of the SCR catalyst and compared to a value provided by a NOx emission model, represents the emissions upstream of the SCR catalyst. The use of a modeled value for the NOx nitrogen oxide emissions upstream of the SCR catalyst advantageously avoids the integration of a NOx detector upstream of the SCR catalyst.
    According to a preferred development, the signal of the nitrogen oxide detector NOx installed downstream of the catalyst SCR is compared with at least one signal of a nitrogen oxide detector NOx upstream of the catalyst SCR. This makes it possible to advantageously use an NOx nitrogen oxide detector, upstream of the SCR catalyst, which thus avoids a complex modeling of the value or level of the NOx nitrogen oxides upstream of the SCR catalyst.
    The method according to the invention for monitoring NOx nitrogen oxide detectors consists of several steps. First, the NOx nitrogen oxide detectors and temperature detectors of the exhaust gas aftertreatment system are connected. Then, it is checked whether the inlet temperature of the SCR catalyst is below the temperature threshold. Then, the NOx nitrogen oxide detector is monitored and at the same time the inlet temperature of the SCR catalyst is monitored.
    Advantageously, the NOx detectors are heated before the end of the dew point. The time of the end of the dew point is predefined in the control unit, in particular with a time safety interval. An advantage of this process is that the NOx nitrogen oxide detectors are ready to measure very quickly after the vehicle is started up and they allow the NOx nitrogen oxide detector monitoring method to be applied very little. long after starting the engine.
    Preferably, the comparison of NOx nitrogen oxide values consists in cross-linking these values, which is a statistically simple method for comparing two values with one another.
    According to one development, the NOx nitrogen oxide signal obtained downstream of the SCR catalyst and also that upstream of the SCR catalyst is compared with a modeled value. This allows a pointing so that it can be determined in a simple and advantageous manner which of the two NOx nitrogen oxide detectors has a defect.
    According to another development, the NOx nitrogen oxide detector signal comparison is used to control and / or regulate the exhaust aftertreatment system. The very accurate comparison of NOx nitrogen oxide detectors advantageously provides important information for the control and regulation of the exhaust gas aftertreatment system. The signals provided by the NOx nitrogen oxide detectors are important inputs for pre-ordering and regulating or adjusting the dosing of the reducing agent for the SCR catalyst. In addition, the determination according to the invention of the behavior of NOx nitrogen oxide detectors in the case of an exhaust gas treatment plant, cold and non-active, will be more precise, simpler and more reliable. that the exploitation of the NOx detector signals for an active SCR catalyst. The results of the NOx nitrogen oxide detector monitoring according to the invention can learn this information concerning the drift of NOx nitrogen oxide detectors. The invention also relates to a computer program for performing the steps of the method and in particular when the program is executed by a computer or an electronic control device. This makes it possible to implement the method according to the invention on an electronic control device without having to make constructive modifications. The invention also relates to a machine-readable memory medium containing the recording of the program as well as an electronic control device for carrying out the method of the invention.
    drawings
    The present invention will be described hereinafter in more detail with the aid of examples of exhaust gas aftertreatment systems shown in the accompanying drawings in which: FIG. 1 is a diagram of a first system of exhaust gas after-treatment according to which, in application of an exemplary method of the invention, the nitrogen oxide detectors NOx are monitored, FIG. 2 schematically shows a second system for the aftertreatment of the nitrogen gases. Exhaust which monitors NOx nitrogen oxide detectors with program corresponding to an exemplary embodiment of the invention, FIG. 3 is a flow chart of an embodiment of the method of the invention, and FIG. a diagram of the temperature plot of an SCR detector.
    Examples of embodiment of the invention
    FIG. 1 schematically shows a first exhaust gas after-treatment system 1 of a motor vehicle (not shown) according to which, with the method of an exemplary embodiment of the invention, the detectors of NOx nitrogen. The exhaust gas after-treatment system 1 comprises a catalyst NSC / cDPF (NOx nitrogen oxide storage catalyst) a diesel particulate filter, with a coating 2, at a reducing agent dosing point 3, a catalyst SCR 4, a first detector of nitrogen oxides 5 upstream of the catalyst SCR 4, a second detector of nitrogen oxides NOx 6 downstream of the catalyst SCR 4, a first temperature detector 8 upstream of the catalyst NCS / cDPF 2, a second temperature detector 9 downstream of the NCS / cDPF catalyst 2 and an electronic control device 7. The control device 7 has a data transmission link with the NOx detectors 5, 6 and the temperature detectors 8, 9.
    FIG. 2 schematically shows a second exhaust aftertreatment system 10 of a motor vehicle (not shown) which monitors NOx nitrogen oxide detectors with a method according to an exemplary embodiment of the invention .
    The exhaust aftertreatment system 10 comprises, as the exhaust gas after-treatment system 1 shown in FIG. 1, a catalyst SCR 4, a first nitrogen oxide detector NOx 5 upstream a catalyst SCR 4 and a second nitrogen oxide detector NOx 6 downstream of the catalyst SCR 4. In addition, the exhaust aftertreatment system 10 comprises another NOx nitrogen oxide detector 12 upstream of the catalyst SCRF (catalyst SCR with a particulate filter) 11, a reducing agent dosing point 3, a first temperature detector 13 upstream of the catalyst SCR 4 and a second temperature detector 14 upstream of the catalyst SCRF 11. Finally, the exhaust aftertreatment system 10 has an electronic control unit 7 connected by a data link with the three nitrogen oxide detectors NOx 5, 6, 12 and the two sensors of the engine. temperature 13, 14.
    Figure 3 schematically shows the progress of an embodiment of the method according to the invention. Firstly, the process will be described in connection with the first exhaust gas after-treatment system 1. The method is executed in several steps. At the beginning of the process, the vehicle is started up in step 20. This step connects NOx nitrogen oxide detectors 5, 6 and temperature detectors 8, 9 as well as the connection of the detector heating. nitrogen oxides NOx, 5, 6 as well as the two nitrogen oxide detectors NOx 5, 6 heated well before the end of the dew point. The dew point time has been predefined with a time offset as a safety interval in the control unit 7.
    In the following step 21 it is checked whether the detectors 5, 6, 8, 9 are ready for operation. If the detectors 5, 6, 8, 9 were not ready, the execution of step 21 of the method is repeated. If in step 21 it is found that the detectors 5, 6, 8, 9 are ready to measure, then in step 22 it is checked whether the inlet temperature Te of the catalyst SCR 4 is below a threshold of temperature Tth predefined, by checking the signal of the temperature detector 9. In this embodiment, the temperature threshold Tth is almost the so-called trigger temperature, that is to say the temperature from which the catalyst SCR 4 becomes active and applies its reducing effect. For safety, we subtract another preset value of the trigger temperature, so that the threshold Tth is slightly below the trigger temperature. The end of the dew point is thus above the temperature threshold Tth. If the inlet temperature Te of the catalyst SCR 4 exceeds the temperature threshold Th, then step 23 monitors the nitrogen oxide detectors NOx 5, 6.
    If step 22 finds that the inlet temperature Te of the catalyst SCR 4 is below the threshold temperature Tth, then in the following step 24, the temperature detectors 5, 6 are monitored and at the same time the temperature is monitored. step 25 continuing to monitor the inlet temperature Tc of the SCR catalyst 4. In step 24, the modeled NOx nitrogen oxide emission values are calibrated each time at the corresponding positions of the detectors 5, 6 using a template. As soon as the input temperature Te exceeds the threshold temperature Tth, the monitoring is stopped in step 23 and the result is rejected. As long as the temperature Te of the catalyst SCR 4 is lower than the temperature threshold Tth, the monitoring of the nitrogen oxide detectors NOx 5, 6 is continued.
    To monitor the nitrogen oxide detector NOx 6 its signal is compared to the NOx 5 nitrogen oxide detector signal upstream of the SCR catalyst 4. If the two nitrogen oxide detectors NOx 5, 6 are intact, the nitrogen oxide detector NOx 6 installed downstream of the catalyst SCR 4 gives the same value of NOx nitrogen oxides as the nitrogen oxide detector NOx 5 and the two oxide detectors NOx NOx nitrogen, have identical dynamic behavior. If the process of one of the two detectors differs, it makes it possible to note a defect. For this, in step 26 it is checked whether the signals of the two nitrogen oxide detectors 5, 6 are identical. In this case, in step 27 of the process, the indication is issued that the nitrogen oxide detector NOx 5, 6 is intact. If in step 26 it is found that the signals of the two nitrogen oxide detectors NOx 5, 6 are different, then a pointing is performed in step 28 of comparing the signals of the two oxide detectors. nitrogen NOx, respectively at a modeled value already calculated in the detector 24 and which is the reproduction of NOx model of emission of nitrogen oxides in two respective positions of the detectors 5, 6. As a result of this pre-score, the result 29 which indicates that of the two detectors NOx 5, 6 which is not intact.
    To explain the timing diagram of the process of FIG. 4, reference is made to the inlet temperature Te of the catalyst SCR as a function of time. Just before starting the vehicle, for t = 0, both detectors are ready to measure. The status signal of NOx nitrogen oxide detectors is characterized by line II. At the point of intersection of the line II and the inlet temperature Te starts the time window during which the nitrogen oxide detector NOx 6 is monitored. During this time, the inlet temperature Te increases. . As soon as the input temperature Te exceeds the threshold temperature Tth, the nitrogen oxide detector NOx 6 can no longer be monitored. This instant thus indicates the end of the monitoring window bearing the reference I in FIG. .
    According to another embodiment, in order to compare the NOx 6 nitrogen oxide detector signal with a NOx nitrogen oxides value upstream of the SCR 5 catalyst, a cross correlation is applied. The cross correlation is calculated for example by applying the following formula:
    In this formula, Inox represents the curve of the nitrogen oxides NOx value upstream of the catalyst SCR 4. fNox6 describes the curve of the NOx value downstream of the catalyst SCR 4 and τ represents the shift in time of the two curves nitrogen oxides NOx values.
    According to another embodiment, the comparison of the NOx values downstream and upstream of the catalyst SCR 4 is applied for the control and regulation of the aftertreatment system of the exhaust gases 1. The NOx detector signals thus obtained are the input signals of the pre-control and the regulation or adaptation of the dosing of the reducing agent solution.
    All the embodiments described above are also carried out in the exhaust after-treatment system 10 shown in FIG. 2. In this case, however, the inlet temperature Te of the SCR catalyst 4 is monitored. with the temperature sensor 14. The NOx 12 detector compares the three nitrogen oxide detectors NOx 5, 6 and 12. This allows very early diagnosis of NOx nitrogen oxide detectors exposed to drift.
    NOMENCLATURE OF THE MAIN ELEMENTS 1 Exhaust Aftertreatment System 2 Storage Catalyst 3 Reducing agent dosing point
    4 SCR Catalyst 5 First nitrogen oxide detector NOx 6 Second nitrogen oxide detector NOx 7 Electronic control unit 8, 9 Temperature sensors 10 Second exhaust after-treatment system
    11 SCRF Catalyst 12 NOx nitrogen oxide detector 13 First temperature sensor 14 Second temperature sensor 20-29 Process steps
    Te SCR catalyst inlet temperature
    Tth Temperature threshold
    权利要求:
    Claims (10)
    [1" id="c-fr-0001]
    RE VEN DIC ATI ONS 1 °) A method for monitoring nitrogen oxide detectors (5, 6, 12) of an exhaust gas aftertreatment system (1, 10) of a motor vehicle comprising at least one SCR catalyst (4), characterized in that the signal of a NOx nitrogen oxide detector (6) downstream of the SCR catalyst (4) is compared to a NOx value upstream of the catalyst SCR (4), before the SCR catalyst (4) exceeds a temperature threshold (T-rh).
    [0002]
    Method according to Claim 1, characterized in that the signal of a NOx nitrogen oxide detector (6) installed downstream of the SCR catalyst (4) is compared to a value of a model of NOx emission, representing the emissions of NOx nitrogen oxides upstream of the SCR catalyst (4).
    [0003]
    Method according to Claim 1, characterized in that the signal of the NOx nitrogen oxide detector (6) placed downstream of the SCR catalyst (4) is compared with at least one signal of a detector of NOx nitrogen oxides (5, 12) upstream of the SCR catalyst (4).
    [0004]
    4) Method according to any one of claims 1 to 3, characterized in that it comprises the following steps consisting of: a. connect (20) the detectors, b. checking (22) whether the inlet temperature (Te) of the SCR catalyst (4) is below a temperature threshold (Tth), and c. monitor (24) the NOx nitrogen oxide detector (6) by simultaneous monitoring of the inlet temperature (Te) of the SCR catalyst (4).
    [0005]
    Process according to one of Claims 1 to 4, characterized in that NOx nitrogen oxide detectors (5, 6, 12) are heated before reaching the end of the dew point.
    [0006]
    Process according to one of Claims 1 to 5, characterized in that a cross-correlation of the values is obtained by comparing the values of the NOx nitrogen oxides.
    [0007]
    Process according to one of Claims 1 to 5, characterized in that the nitrogen oxide signal NOx downstream of the SCR catalyst (4) and the upstream one is compared with a modeled value. SCR catalyst (4).
    [0008]
    Process according to one of Claims 1 to 7, characterized in that the comparison of the signals supplied by the NOx nitrogen oxide detectors (5, 6, 12) is used for the control and / or regulation of the aftertreatment system of the exhaust gases (1, 10).
    [0009]
    9) A computer program comprising program code instructions for executing the steps of the method according to any one of claims 1 to 8 when this program is executed on a computer.
    [0010]
    10 °) Computer readable recording medium on which is recorded a computer program comprising program code instructions for performing the steps of the method according to any one of claims 1 to 8.
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    同族专利:
    公开号 | 公开日
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    法律状态:
    2017-09-08| PLSC| Publication of the preliminary search report|Effective date: 20170908 |
    2018-01-24| PLFP| Fee payment|Year of fee payment: 2 |
    2020-01-23| PLFP| Fee payment|Year of fee payment: 4 |
    2021-01-20| PLFP| Fee payment|Year of fee payment: 5 |
    2022-01-18| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    DE102016200721.1A|DE102016200721A1|2016-01-20|2016-01-20|Method for monitoring NOx sensors|
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