FR3064673A1 - CONTROL METHOD AND INSTALLATION FOR MONITORING THE OPERATION OF A DIESEL PARTICULATE FILTER - Google Patents

Abstract

A method for monitoring the operation of a diesel particulate filter of the exhaust gas duct according to which the emission of carbon black is determined downstream of the filter by means of a particle sensor, the emission is modeled predictable particulate matter downstream of a diesel particulate filter at the location of the particulate sensor, and it is considered that the filter is in order if the emission of measured carbon black is less than the emission of lampblack modeled and that the filter is defective in the opposite case. The modeled concentration of particles at the sensor mounting location is taken as the modeled emission of smoke.

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number: 3,064,673 (to be used only for reproduction orders)

©) National registration number: 18 52726

COURBEVOIE © IntCI ⁸ : F 01 N 11/00 (2017.01), F 01 N 3/021

A1 PATENT APPLICATION

©) Date of filing: 29.03.18. © Applicant (s): ROBERT BOSCH GMBH— DE. © Priority: 31.03.17 DE 102017205507.3; 04.04.17 DE 102017205690.8. @ Inventor (s): EITEL MARKUS and HERBERGER PATRIK. (43) Date of public availability of the request: 05.10.18 Bulletin 18/40. ©) List of documents cited in the report preliminary research: The latter was not established on the date of publication of the request. (© References to other national documents ® Holder (s): ROBERT BOSCH GMBH. related: ©) Extension request (s): © Agent (s): CABINET HERRBURGER.

CONTROL METHOD AND INSTALLATION FOR MONITORING THE OPERATION OF A DIESEL PARTICLE FILTER

FR 3 064 673 - A1 ftv) Method for monitoring the operation of a diesel particulate filter of the exhaust gas duct according to which the emission of smoke black downstream of the filter is determined using a sensor of particles, we model the expected emission of particles downstream of a diesel particulate filter limit at the location of the particle sensor, and it is estimated that the filter is in order if the emission of smoke black measured is lower when the modeled smoke black is emitted and the filter is defective otherwise.

The modeled concentration of particles at the sensor mounting location is taken as the emission of modeled black smoke.

Field of the invention

The present invention relates to a method and a control installation for monitoring the operation of a diesel particulate filter.

In other words, the invention relates to a method for monitoring the operation of a diesel particulate filter of the exhaust gas duct of an internal combustion engine according to which the emission of smoke black is determined. in the exhaust gas duct downstream of the diesel particulate filter using a particle sensor, the predicted emission of smoke black particles is modeled downstream of a diesel particulate filter limited to l location of the particle sensor and the diesel particulate filter is considered to be in order if the measured smoke black emission is lower than the modeled smoke black emission and the diesel particulate filter is considered to be defective if the measured smoke black emission is greater than the modeled smoke black emission.

The invention also relates to a control installation for monitoring the operation of a diesel particulate filter of the exhaust gas duct of an internal combustion engine in which the exhaust gas duct has downstream of the filter particle filter, a particle sensor to determine the degree of deterioration of the diesel particulate filter, the estimated time is calculated until reaching a current threshold value downstream of a diesel particulate filter limit at the location of the sensor of particulate matter and it is estimated that the diesel particulate filter is in order if the time measured until reaching a current threshold value is greater than the forecast time until reaching a current threshold value and that the diesel particulate filter is defective if the time measured to reach a current threshold value is less than the forecast time until it reaches a current threshold value.

State of the art

Vehicles equipped with diesel internal combustion engines are fitted with a diesel particulate filter (also called a DPF filter) installed in the exhaust gas duct to comply with the regulations concerning the emission of particles. The onboard gnostic dia3064673 rule (also called OBD2 rule) requires monitoring the components of the vehicle concerned by the exhaust gases and thus also monitoring the proper functioning of the diesel particulate filter. By lowering the OBD limit for the emission of particles according to different regulations (CARB regulation, MY13: 17.5 mg / mi; European regulation Euro6-2: 12 mg / Km) European regulation EUVI-C: 25 mg / kWh) in in many cases you can no longer monitor using the differential pressure of the particulate filter. However, a particle sensor is required behind the diesel particulate filter. In the event of a defective diesel particulate filter, the smoke black particles are deposited on two electrodes of the particle sensor. These electrodes interpenetrate like the teeth of a comb and their electrical conductivity decreases the electrical resistance between the electrodes. By applying an electrical voltage, an electrical current can thus be measured. Under these conditions, from a smoke black deposit threshold, the current increases as a function of the smoke black occupation. If the current exceeds a threshold for a predefined occupancy time, it will be considered in the sense of the OBD2 regulation, that the particle filter is defective. To start a new measurement cycle, the particle sensor is heated to burn the accumulated smoke black particles.

Due to the principle operation of the particle sensor working by collection, it is not possible to directly measure the concentration of smoke black in the exhaust gases, this measurement being made during the period until the intensity increases above from the threshold. This measured time is compared to a time predicted from a comparison model. This comparison model includes, among other things, the concentration of the particulate filter as an input quantity. This concentration of smoke black particles is provided by another model which, depending on parameters such as the engine operating point, the concentration of oxygen in the exhaust gases and / or the rate of recycling of exhaust gases. exhaust (AGR rate) gives a mass flow of smoke black particles downstream of the limit diesel particulate filter, operated in accordance with OBD regulations. In the DFP diagnostic function, the concentration of smoke black particles is calculated by calculation from the mass of smoke black particles for the comparison model. This can also be done using the diagnostic function to determine if there is a DFP fault or if the DPF operation is in order.

According to document DE 10 2014 206 252 B4, a method is known for diagnosing the suitability for operation of a particulate filter installed in the exhaust gas pipe of an internal combustion engine, comprising the following steps consisting in: :

execute an emission test with the vehicle and measure the particle emission using a particle sensor installed downstream of the particle filter for a first emission limit value, fixed to obtain a first model value of particles (RMI), perform an emission test with the vehicle and measure the emission of particles using the particle sensor for a second fixed emission value to obtain a second modeled value of particles (RM2), measure the emission of particles during vehicle operation using the particle sensor and obtain a measurement value of particle emission (R), issue a diagnostic value (FACnom) according to the following formula

FACnom = ^Ml ;

compare the diagnostic value obtained (FACnom) with a fixed limit value and classify the diesel particulate filter as intact if the diagnostic value is lower than the limit value or estimate that the particulate filter is defective if the diagnostic value exceeds the limit value, * the first emission limit value corresponds to the EU6 particle filter emission limit value (ELimit-DFP) and the second, fixed emission value corresponds to the OBDLimitDFP limit value, associated with the limit value on-board diagnostic EU6 (OBDLimit-DFP).

Document DE 10 2013 206 451 A1 describes a process for monitoring the performance of a particulate filter installed in the exhaust gas pipe of an internal combustion engine and comprising the following steps:

perform a first diagnostic phase by determining an efficiency value of the particulate filter and comparing it with a forecast result, reaching or exceeding the forecast value by fixing the efficiency value in the event of a suspected fault;

fixes a supposed defect in the fault flag by increasing the emissions of the particulate filter in the exhaust gases from the vehicle engine and thus reducing the dispersion of the value obtained from the efficiency of the filter, and performing a second phase of diagnostic similar to the first diagnostic phase.

Document DE 10 2013 206 391 A1 describes a process for verifying the suitability for operation of a particle filter installed in the exhaust gas duct of a motor vehicle engine and comprising the following steps:

measure the concentration of particles c_l in the exhaust gases downstream of the particle filter for a first operating point, determine the degree of efficiency of the filter (eff_l) from the measured concentration of particles (c_l) and the modeled concentration of particles downstream of the particle filter, alternate the engine operating point for a second operating point so that particle emissions increase sharply downstream of the particle filter, measure the concentration of particles (c_2) contained in the exhaust gases downstream of the particulate filter for a second operating point, determine the efficiency of the particulate filter (eff_2) for the second operating point in a similar manner to the procedure applied for the first operating point, determine the absolute difference between the filter efficiency degrees (eff_l and eff_2), and note a mismatch if the absolute difference between the filter yields (eff_l and eff_2) exceed a fixed threshold.

Purpose of the invention

The object of the present invention is to develop a method making it possible, by the use of a smoke black particle data model, to make a simple diagnosis of the operability of a diesel particulate filter.

The invention also aims to develop a control installation for the implementation of such a process.

Presentation and advantages of the invention

To this end, the subject of the invention is a process for monitoring the operation of a diesel particle filter of the type defined above, characterized in that the modeled concentration of black particles is taken as emission of black smoke smoke at the mounting location of the particle sensor. The modeling avoids multiple conversions of the concentrations of smoke black into mass flow of smoke black and conversely the conversion into concentration of smoke black. This avoids the risk of losing data through conversions. The diagnosis of the operability of the particulate filter is thus simpler. Another advantage of continuous use of the concentration values is that of a good correlation between the concentration of smoke black with other quantities of the exhaust gases, which simplifies the model. This advantageously results in a reduction in the number of characteristic curves and characteristic fields. The process thus reduces the amount of data and the duration of calculations.

Since the modeled concentration of smoke black particles is loaded with model building data together with the smoke black concentration data, it is possible to use the devices typically used in reference measurement technique, such as for example the MSS sensor (Micro Scoot Sensor) which determines the concentrations of smoke black without having to convert the supplied values of the concentrations to pass into masses of smoke black.

The invention also relates to a control installation of the type defined above, characterized in that it comprises a program or a circuit for modeling the concentration of smoke black particles as emission of smoke black modeled at l installation location of the particle sensor.

This control installation is simplified by reducing the calculations.

Drawing

The present invention will be described below, in more detail, with the aid of an exemplary embodiment shown in the attached figure which is a model of concentration of smoke black according to the invention.

Description of an embodiment of the invention

The state of the art is that of smoke black modeling based on different cases of mass flow of smoke black particles. The disadvantage of this process is that it requires a double conversion of the concentration into a mass flow and then into a concentration. This results in significant calculations with the risk of losing data through conversions.

The single figure shows a model of black smoke concentration 10 according to the invention. The black smoke concentration model 10 is used as a comparison model for the input variables used to monitor the operation of the diesel particulate filter and to judge whether the diesel particulate filter is defective or functioning properly. For this, the corrected smoke black concentration 20 downstream of a diesel particulate filter, limit, is used as a comparison value. In the smoke black concentration model 10, the basic smoke black concentration 11 is corrected in a first combination point 12 with an oxygen correction 13 which takes account of the oxygen concentration contained in the exhaust gases. The smoke black concentration 11 corresponds to the fixed smoke black emissions at the installation position of the particle sensor used to monitor this diesel particulate filter. Oxygen correction 13 takes into account the deviations of a predicted oxygen concentration predicted in relation to an oxygen concentration measured in the exhaust gases with a lambda probe or the oxygen concentration determined from the signal d oxygen supplied by a nitrogen oxide sensor. These deviations influence the emission of smoke black so that it is planned to correct the concentration of smoke black in the smoke black concentration model 10 according to the difference between the current concentration and the expected concentration of oxygen as well as the injected fuel dose, in a first field of characteristics to be corrected and, if necessary, being limited to predefined ranges.

According to a second combination point 14, a dynamic correction 15 is carried out which takes account of the current operating point of the engine. For the dynamic correction 15 the gradient of the fuel injection dose or of an engine torque is formed and the engine rotation speed is used in a fourth field of characteristics which corrects the modeled concentration of black smoke. In addition, one can also take into account the gradient of the rotation speed and the environmental conditions such as the ambient pressure, the temperature of the environment, the temperature of the cooling water, the coefficient of gas reintroduction. exhaust and the lambda coefficient.

The result of the second combination point 14 is corrected by an AGR correction 17 at the third combination point 16, this correction taking into account the exhaust gas reinjection rate (AGR rate). The main AGR correction coefficient for modeled emissions of black smoke, for the DPF diagnostic is based on the current total AGR coefficient and the ambient temperature. The resulting correction coefficient can be corrected even more with the characteristics depending on the ambient pressure and the engine temperature.

The result of combination 16 is corrected by a fourth combination 18 with another AGR low pressure correction coefficient 19 which takes account of an additional AGR low pressure component. For this correction, the overall AGR coefficient and the low pressure AGR component are used as the input quantity in a correction field.

To smooth the output signal, the result of combination 18 is filtered with a first order low pass filter (PT1 filter). The result is the corrected concentration of smoke black 20.

A diagnostic function 30 compares the corrected concentration of smoke black 20 downstream of a diesel particulate filter limiting the concentration of smoke black determined in the exhaust gases downstream of the particulate filter. This makes it possible to determine in the diagnostic function 30 whether or not the diesel particulate filter is defective. This avoids multiple conversions from the concentration to a mass flow and vice versa to pass from it to a concentration.

Claims (3)

1 °) Method for monitoring the operation of a diesel particulate filter of the exhaust gas duct of an internal combustion engine according to which the emission of smoke black in the downstream exhaust gas duct is determined of the diesel particulate filter using a particle sensor, we model the predicted emission of smoke black particles downstream of a limit diesel particulate filter, at the location of the particle sensor, and we estimates that the diesel particulate filter is OK if the measured smoke black emission is lower than the modeled smoke black emission and it is estimated that the diesel particulate filter is defective if the measured smoke black emission is greater than the emission of modeled smoke black, process characterized in that the emission of modeled smoke black is taken as the modeled concentration of particles of smoke black at mounting location of the particle sensor. 2 °) Method according to claim 1, characterized in that when establishing the model, the concentration of smoke black concentration is assigned to the modeled concentration of smoke black particles. 3 °) Control installation for monitoring the operation of a diesel particulate filter of the exhaust gas duct of an internal combustion engine in which - the exhaust gas duct has a particle sensor downstream of the particulate filter to determine the degree of deterioration of the diesel particulate filter, - the estimated time is calculated until a current threshold value is reached downstream of a limit diesel particulate filter, at the location of the particle sensor, and ίο - it is estimated that the diesel particulate filter is in order if the time measured until reaching a current threshold value is greater than the forecast time until reaching a current threshold value and that the diesel particulate filter is defective if the time me5 sure to reach a current threshold value is less than the forecast time until reaching a current threshold value, control installation characterized in that it comprises a program or a circuit for modeling the concentration of smoke black particles as the emission of smoke black modeled at the installation location of the particle sensor. 1/1 12 14 16 18 20