METHOD FOR INITIATING THE REGENERATION OF A PARTICULATE FILTER

Description

[0001] The present invention relates to a method for initiating so-called dysfunctional regeneration of a particulate filter in a powertrain with spark-ignition engine.

[0002] Upcoming anti-pollution standards, particularly in Europe with the upcoming application of the Euro 6 2nd stage emissions regulation, significantly tighten the threshold to be met for particles emitted by engines with Direct Injection spark ignition or later indirect injection.

[0003] Compliance with such regulations could require the use of a particulate filter in the exhaust system of such engines. Such a particulate filter for spark-ignition engines running on gasoline, also commonly known as a GPF (Gasoline Particle Filter), is relatively similar to those used for diesel engines, but its characteristics are adapted so as not to negatively impact performance or fuel consumption.

[0004] An exhaust line includes an exhaust gas circulation duct equipped with chemical and / or physical exhaust gas treatment devices, for example at the outlet of a spark-ignition internal combustion engine, an advantageously three-way catalyst, a particulate filter housed inside a metallic casing, also called by the English term "canning", this metallic casing being common to the catalyst and the particulate filter.

[0005] The particulate filter in an exhaust system serves to retain soot within it. The filtration principle is identical to that of a particulate filter for diesel engines; that is, filtration is based on the passage of soot through porous channels.

[0006] After a certain period of time or distance traveled, a particulate filter becomes clogged with particles, particularly soot. It then needs to be cleaned or regenerated. This regeneration process involves burning off the soot. To burn the soot, the engine can switch to a specific combustion mode that raises the exhaust gas temperature to approximately 650°C to burn the soot within the particulate filter, without the use of any combustion aids. Regeneration therefore occurs at high temperatures in the presence of an oxygen supply.

[0007] For spark-ignition gasoline engines, these conditions are naturally present for passive regeneration, which is in fact almost continuous. Therefore, there is generally no regeneration triggering during normal operation, also known as functional regeneration. Consequently, for a gasoline engine, a significant portion of the engine's operating range provides the necessary heat, and oxygen can be supplied through fuel injection cut-offs during deceleration or gear changes. All of this creates the conditions for passive regeneration.

[0008] However, strategies have been implemented for atypical drivers, and a so-called dysfunctional or "active" regeneration process is triggered when the particulate filter contains approximately 5 grams of soot. Atypical drivers are those who make short trips, for example, less than 15 km, at low speeds. Gear shifting and driving style (whether sporty or not) also influence the effectiveness of the regeneration process.

[0009] The mass of soot contained in the particulate filter needs to be monitored. This can be done by checking the pressure difference across the particulate filter, ideally with an estimate of the exhaust gas flow rate through the filter. It is important that this measurement be taken at the particulate filter terminals and not between points upstream and downstream of the filter. However, this measurement may be missed for a brief period during driving or may exhibit fluctuations.

[0010] Indeed, pollution control elements in the vicinity of the gasoline particulate filter, particularly the three-way catalyst, can create dispersions and distort pressure difference measurements and the estimation of the mass of soot stored in the gasoline particulate filter.

[0011] Other estimates can be made from the exhaust gases emitted by the engine. These estimates are less precise than those based on a pressure differential but can compensate for a missing pressure differential estimate. Combustion models can be developed for these estimates.

[0012] As the use of the particulate filter in a spark-ignition gasoline engine is recent, there is little state of the art relating to preventive regenerations of such a gasoline particulate filter.

[0013] Document FR-A-2 963 641 describes a method for initiating targeted regeneration of a particulate filter in the exhaust gas line of an internal combustion engine with a catalyst downstream of the particulate filter. The particulate filter regeneration occurs through combustion of the particles during the regeneration phase. Other methods are described in the following publications: WO 03 / 025355 A1, US 2017 / 159522 A1, and FR 2963641 A1.

[0014] For a hot engine that is not yet at a temperature sufficient for particulate filter regeneration, the exhaust gas temperature is periodically increased upstream or within the particulate filter. This process applies to gasoline engines but provides no indication of the precise estimation of soot mass or the monitoring of regeneration.

[0015] Therefore, the problem underlying the invention is, for a powertrain comprising a spark-ignition internal combustion engine and an exhaust line housing a particulate filter, to accurately estimate the soot load contained in the filter so that the conditions for a so-called dysfunctional regeneration of the particulate filter can be optimal.

[0016] To achieve this objective, the invention provides a method for initiating a dysfunctional regeneration of a particulate filter in the exhaust line of a spark-ignition internal combustion engine equipping a motor vehicle. The so-called dysfunctional regeneration is initiated when a so-called functional or passive regeneration cannot take place due to a driving profile that prohibits it by failing to reach a minimum regeneration temperature, by having an insufficient driving time, or by having an insufficient oxygen supply in the exhaust line for its operation. The method comprises a step of identifying a common driving profile that prohibits functional or passive regeneration, a step of estimating a current soot mass in the particulate filter and a current filter load from the current mass, and, when the current load is greater than a minimum threshold,a step of modifying the combustion parameters to obtain a temperature in the line greater than 600°C and an oxygen mass in the line at least greater than 2% of the total gas mass in order to perform the dysfunctional regeneration, characterized in that the estimation step is performed simultaneously based on three mass estimates from, firstly, a measurement of a pressure differential across the particulate filter terminals, secondly, an estimate of the engine emissions since the last regeneration taking into account an estimate of natural soot combustion since the last regeneration and, thirdly, an estimate of the engine emissions taken in isolation to which a predetermined safety multiplicative factor greater than 1 is applied and, when a pressure differential measurement is available, the second estimate is recalibrated with respect to at least the first estimate.

[0017] The technical effect is to trigger a malfunctioning regeneration, also known as preventive regeneration, by adjusting at least one combustion parameter after detecting a soot load in the particulate filter above an intermediate threshold. The soot load is estimated using three parallel estimation processes. The first estimate, which is the most reliable based on pressure differential, is not always available and is then replaced by one of the other estimates. Furthermore, this first estimate can sometimes produce false readings due to excessive dispersion and interference from elements located near the particulate filter.

[0018] This allows the estimates to be recalibrated against each other. The second estimate, less precise because it is based on exhaust gas emissions in the exhaust system, is recalibrated at least against the first estimate and, if necessary, the third estimate, which represents a safety margin for protecting the particulate filter. Thus, for the load estimation, which is an essential step in the present invention to avoid initiating unnecessary malfunctioning regeneration or, conversely, to initiate malfunctioning regeneration before a high soot load is reached in the filter, this estimation is based on three parallel estimates. This allows for a comparison of the models from each of the three estimates and for corrections to be made.

[0019] During malfunctioning regeneration, combustion in the engine may be degraded compared to optimal combustion, but this or these adaptive measures are a strong lever for initiating regeneration by increasing the temperature and oxygen supply in the exhaust line containing the particulate filter.

[0020] Advantageously, the dysfunctional regeneration of the particulate filter is carried out if authorization conditions are met and prohibition conditions are lifted, the authorization conditions being a current load between the minimum threshold and a maximum threshold presenting a risk of damage to the filter during regeneration, an implementation of the step of modification of the combustion parameters with an engine temperature above a predetermined minimum temperature and a driving time above a minimum time, the prohibition conditions being lifted if the vehicle has traveled a minimum distance since the last regeneration carried out.

[0021] The exhaust temperature must be high enough to trigger a malfunctioning regeneration. This prevents further damage to combustion within the engine, thus reducing fuel consumption. The requirement for a minimum mileage between regenerations prevents them from being performed consecutively.

[0022] Advantageously, the current load is obtained as a function of the current mass that divides an internal volume of the particle filter.

[0023] Advantageously, the modified combustion parameters are, taken individually or in combination, an under-timing of an ignition advance resulting in an increase in the temperature of the exhaust gases in the line, cuts or modifications of fuel injection in the engine with a richness less than one for an oxygen supply in the line.

[0024] The adjustments can be made simultaneously or sequentially. For example, the temperature in the fuel line can be increased before oxygen is introduced. Since everything is automatic, the driver of a vehicle does not need to worry about initiating the malfunctioning regeneration; they can simply be aware that such a regeneration is in progress and choose not to stop the vehicle during the process to complete it, but this is not mandatory. When the ignition timing is adjusted, the degradation of the combustion pattern is barely perceptible, especially in a moving vehicle.

[0025] Advantageously, a delay is observed between an estimate of a current load that would allow for a malfunctioning regeneration and the initiation of the malfunctioning regeneration. This allows for the adaptation of one or more combustion parameters, particularly concerning the temperature rise of the exhaust system and the particulate filter.

[0026] Advantageously, during dysfunctional regeneration, the current mass is followed by the second and third estimates and a dysfunctional regeneration progression factor is estimated based on a determination of a final target mass and, when this final target mass is reached, the progression factor is equal to one and, when the engine is stopped before the end of dysfunctional regeneration, the progression factor is stored with, when this factor exceeds a minimum progression threshold, a qualification of dysfunctional regeneration as sufficient.

[0027] The progression factor allows you to track the progress of a regeneration and serves as a reference point when a malfunctioning regeneration stops when the vehicle's engine is stopped, possibly for resuming this regeneration at the next start.

[0028] Advantageously, at the end of a complete or sufficient malfunctioning regeneration, the soot mass estimates from the first and third estimates are updated relative to the value given by the second soot mass estimate. The differential pressure estimate may then have been skewed, whereas the reset emissions estimate is relatively reliable at the very beginning of a particulate filter soot load estimation.

[0029] Advantageously, when the vehicle is stopped, for a factor that is below the minimum progression threshold, the dysfunctional regeneration is resumed at the next engine restart as soon as authorization conditions are met and prohibition conditions are lifted.

[0030] Advantageously, the current driving profile followed by the vehicle is compared or anticipated with identified driving profiles so as not to allow regular full regenerations and if the current driving profile of the vehicle corresponds to one of the stored driving profiles or if it is anticipated to be unfavorable to holding a regeneration, a dysfunctional regeneration is initiated.

[0031] Monitoring driving history can be used to anticipate a vehicle's driving profile by triggering a malfunctioning regeneration. Such a malfunctioning regeneration is also called preventive because it occurs at an intermediate soot load threshold that is lower than the maximum load threshold of the particulate filter. Based on the monitoring, it is recognized that the vehicle has a driving profile unfavorable to regenerations occurring spontaneously or scheduled for maximum soot load in the filter, and that therefore it is advantageous to trigger malfunctioning regenerations at a lower soot load than the maximum soot load.

[0032] This can be refined by comparing the current driving profile with previous driving profiles. It may then be determined that the current driving profile will not allow for spontaneous regeneration and that, therefore, a preventive regeneration should be triggered.

[0033] The invention relates to a motor vehicle powertrain comprising a spark-ignition internal combustion engine, an exhaust system, a control unit responsible for the operation of the internal combustion engine, and a particulate filter monitoring unit that triggers a regeneration of the particulate filter when the soot particle load in the filter exceeds a predetermined minimum load threshold. The exhaust system includes a differential pressure sensor at the terminals of the particulate filter, characterized in that it includes means for implementing such a method of initiating a malfunctioning regeneration. The control unit includes initial means for estimating the mass of soot as a function of the differential pressure measured by the sensor at the terminals of the filter.second means of estimating soot mass as a function of engine emissions since the last regeneration, taking into account an estimate of natural combustion of soot since the last regeneration, and third means of estimating soot mass as a function of engine emissions taken in isolation, with means of determining a safety multiplicative factor, as well as means of comparing the three estimates performed and means of calibrating the second estimate at least to the first estimate.

[0034] To ensure greater safety for the particulate filter, it is also possible to recalibrate the second estimate relative to the third, more conservative estimate using a predetermined safety factor greater than 1. This is in addition to recalibrating the first estimate. This may involve increasing the estimated soot mass. A correction factor for the first estimate using the third can be implemented.

[0035] Other features, purposes, and advantages of the present invention will become apparent from the detailed description that follows and from the accompanying drawings, which are given by way of non-limiting examples and on which: there figure 1 is a schematic representation of an assembly of a naturally aspirated internal combustion engine with spark ignition and an exhaust system comprising a three-way catalytic converter and a particulate filter, such an assembly being able to implement the process according to the present invention, the figure 2 is a flowchart of an embodiment of a method for launching a malfunctioning regeneration of a gasoline particulate filter integrated into an exhaust line of a spark-ignition internal combustion engine of a motor vehicle according to the present invention.

[0036] It should be borne in mind that the figures are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. In particular, the dimensions of the various elements illustrated are not representative of reality.

[0037] In what follows, reference is made to all figures taken in combination. When reference is made to one or more specific figures, these figures are to be taken in combination with the other figures for the recognition of the designated numerical references.

[0038] The term powertrain refers to the internal combustion engine and all its auxiliary components such as an exhaust system, a control unit responsible for the proper functioning of the engine and for controlling emissions in the exhaust system, the powertrain may or may not include a turbocharger.

[0039] A gasoline particulate filter refers to any particulate filter for a spark-ignition engine, particularly for engines running on gasoline or a gasoline-containing fuel mixture. This term is commonly used to distinguish it from a particulate filter for a compression-ignition engine, such as a diesel engine or one running on diesel fuel, but it should not be interpreted in its restrictive sense limited to gasoline fuel.

[0040] With particular reference to the figure 1 , which shows an engine 21 and an exhaust line 18 capable of implementing the method according to the present invention although the engine 21 and the line 18 are not shown with specific features of implementation of the present invention, the invention relates to a method of initiating preventive regeneration of a gasoline particulate filter 22 in a powertrain comprising a thermal engine 21 and an exhaust line 18 incorporating the filter 22.

[0041] A soot load of the filter 22 is measured or estimated, for example by measuring a pressure differential across the terminals of the filter 22 or by estimating the emissions in the exhaust line 18 since a last regeneration and taking into account spontaneous regenerations which have resulted in soot combustion in the filter 22. The load in force in the filter 22 must not exceed a predetermined maximum load threshold.

[0042] There figure 1 Also shown is a respective metallic casing 17 for a three-way catalyst 23 and the particulate filter 22, of which only the casing 17 for the three-way catalyst 23 is referenced. A differential pressure or back-pressure sensor 19 is shown at the terminals of the particulate filter 22, along with an oxygen sensor 20a upstream of the three-way catalyst 23 and an oxygen sensor 20b downstream of the particulate filter 22. All the newly mentioned elements are not essential for the implementation of the present invention except for the sensor 19.

[0043] The present invention relates to a method for initiating a malfunctioning regeneration of a gasoline particulate filter 22 integrated into an exhaust line 18 of a spark-ignition internal combustion engine 21 of a motor vehicle. Such a malfunctioning regeneration is initiated when a functional or passive regeneration cannot occur due to an unfavorable driving profile.

[0044] Functional regeneration means regeneration occurring when the soot load in the filter 22 is close to the maximum soot load threshold, and passive regeneration means spontaneous regeneration occurring for a spark-ignition engine 21 under certain conditions of attainment less severe than the regeneration conditions in Diesel engines.

[0045] Passive or spontaneous regeneration may not occur if a minimum regeneration temperature is not reached in exhaust line 18 or if insufficient driving time has been achieved. This driving time may be insufficient to reach a regeneration temperature. In another case, a lack of oxygen supply to exhaust line 18 may prevent or cause regeneration to fail.

[0046] The method according to the present invention includes a step of identifying a common rolling pattern that prohibits functional or passive regeneration. In this case, a dysfunctional regeneration should be initiated before the particulate filter 22 becomes excessively clogged with soot, given the impossibility of regenerating it through passive or functional regeneration.

[0047] A step is planned to estimate the current soot mass in the particulate filter 22 and the current load Cs of the filter 22 from the current mass Msc. When the current load Cs is greater than a minimum or intermediate threshold, but in any case less than a maximum soot load in the particulate filter 22 that could damage it during regeneration, a step is planned to modify the combustion parameters McsRGa to obtain a temperature in line 18 greater than 600°C and an oxygen mass in line 18 at least greater than 2% of the total gas mass in order to perform the malfunctioning regeneration.

[0048] For dysfunctional regeneration, specific conditions favoring regeneration are not expected, as for spontaneous regeneration, but these conditions are induced as for functional regeneration.

[0049] By referring to the figure 2 , while taking into account the references of the figure 1 , the estimation step is done based simultaneously on three mass estimates 10 to 12 from, firstly, a measurement 10 of a pressure differential across the terminals of the particle filter 22 giving mass estimates of soot MsBF for closed loop mass.

[0050] Secondly, the estimation step is also based on an estimate 12 of the emissions of the engine 21 since the last regeneration, taking into account an estimate of natural combustion of soot since the last regeneration, giving estimates of soot mass MsBO for open loop mass.

[0051] Thirdly, the estimation step is finally carried out based on an estimate 11 of the emissions of the engine 21 taken in isolation to which a predetermined safety multiplicative factor greater than 1 is applied, advantageously for example equal to 1.3, this third estimate 11 giving soot mass estimates MsCC for open loop mass of critical conditions, ensuring the protection of the particulate filter for adverse driving conditions.

[0052] This third estimate 11 functions as a safety mode for critical driving conditions. When a pressure differential measurement from the first estimate 10 is available, the second estimate 12 is recalibrated relative to at least the first estimate 10 based on the differential measurement. This is shown in reference 13.

[0053] In addition to recalibrating against the first estimate 10, the second estimate 12 can be recalibrated against the third estimate 11 for added safety, in the sense of an increase in the mass MsBO determined by the second estimate 12. Thus, the second estimate 12 can be recalibrated against the third estimate 11 using the multiplicative coefficient when the soot mass estimated by the third estimate exceeds a calibrated threshold. Following this recalibration, a current soot mass Msc is known.

[0054] The first estimate 10 gives a soot mass measurement MsBF because it is estimated to be obtained in a closed loop. The second estimate 12 gives a soot mass measurement MsBO because it is estimated to be obtained in an open loop. The third estimate 11 gives a soot mass measurement under critical conditions MsCC. The second and third estimates 12 and 11 are established based on an emission estimate 8, with the second estimate 12 based on a combustion estimate 9.

[0055] Dysfunctional regeneration of the particulate filter 22 may be carried out if authorization conditions 1 are met and prohibition conditions 2 are lifted. Authorization conditions 1 may be a current load Cs between the minimum threshold and a maximum threshold presenting a risk of damage to the filter 22 during regeneration, as well as implementation of the combustion parameter modification step McsRGa with an engine temperature 21 exceeding a predetermined minimum temperature and a driving time exceeding a minimum time.

[0056] The prohibition conditions 2 can be lifted if the vehicle has traveled a minimum distance since the last regeneration, for example 20 km, which is not a strict limit. Reference N to the figure 2 This means that the prohibition conditions 2 are lifted. A minimum temperature condition may also be included in the prohibition conditions 2, but this is not mandatory.

[0057] The current charge Cs can be obtained as a function of the current mass Msc divided by an internal volume 14 of the particle filter 22 obtained after estimating the free volume 14 in the particle filter 22. This gives a charge in grams per liter.

[0058] In step 15, a diagnostic check is performed to determine if the load thresholds have been exceeded, thus authorizing regeneration. The current soot load (Cs) may exceed a predetermined minimum or intermediate threshold to trigger regeneration, but fall below a predetermined maximum threshold to prevent damage to the particulate filter (22) due to excessive exothermic reaction.

[0059] As a rough guide, and without being exhaustive, the minimum or intermediate predetermined threshold could correspond to a mass of 6 grams with a variation range of + / - 20% around this value, and the maximum predetermined threshold could correspond to a soot mass of 15 to 20 grams in the particulate filter 22. The minimum threshold can thus be calibrated to best suit the driving profile.

[0060] For example, without this being limiting, for example, a 22 particulate filter in a vehicle with a history unfavorable to the maintenance of regenerations of the 22 particulate filter with short journeys of less than 15 kilometers, at reduced speed less than 50 km / h and gentle driving without strong accelerations less than 2m / s 2< , may be assigned a lower intermediate threshold than a 22 particulate filter in the vehicle with a less unfavorable history of maintenance of regenerations with long journeys at high speed and sporty driving with strong accelerations.

[0061] When malfunctioning regeneration is enabled, a powertrain control unit, responsible for the combustion operation in engine 21 and the operation of the pollution control elements in the exhaust line 18, including the particulate filter 22 with the initiation of regenerations, stores the current soot mass Msc. This is done in 5.

[0062] Simultaneously, combustion parameters can be modified, which is referenced as McsRGa. These combustion parameters can be, individually or in combination, an under-timing of the ignition advance leading to an increase in the exhaust gas temperature in line 18, fuel injection cut-offs or modifications in engine 21 with a richness ratio less than one for oxygen supply in line 18. Other combustion parameters can also be taken into consideration.

[0063] When the conditions of authorization 1 are met and the conditions of prohibition 2 are lifted, which corresponds to the AND of the figure 2 A dysfunctional regeneration is permitted ARG. When the current estimated soot load Msc reaches the minimum threshold and the operating conditions of the engine 21 allow it, a particulate filter supervisor 22 sends a request for dysfunctional regeneration to a combustion mode manager which can be integrated into a powertrain control unit.

[0064] The mode manager controls the actuators of engine 21 to optimize the supply of heat and oxygen to the exhaust line 18 upstream of the particulate filter 22, necessary for soot combustion. The combustion modes McsRGa are managed in step 3 to apply a specific combustion mode for regeneration.

[0065] A delay 16 can be observed between an estimation of a current load Cs allowing a dysfunctional regeneration and the initiation of the dysfunctional regeneration, which comes as the third condition after the first group of allowing conditions 1 and the second group of prohibiting conditions 2.

[0066] If there is a need for regeneration fixed at the first activation B RG fa, this need for regeneration comes as a necessary condition with the specific combustion mode for regeneration McsRGa for a regeneration in progress fixed at the first activation RG ec fa.

[0067] During this ongoing dysfunctional regeneration, the first estimate 10 is inhibited by pressure differential, and updates for the second estimate 12 are made based on emissions. This is referenced in 4.

[0068] During ongoing dysfunctional regeneration, after memorization of the current soot mass Msc, the evolution of the current soot mass Msc can be monitored by the second and third estimations 12, 11. A progression factor for dysfunctional regeneration can then be estimated based on the determination of a final target mass. This is referenced 6 in the figure 2 The progress factor allows us to determine the progress of the regeneration and to request a return to the nominal operating modes of engine 21 when the regeneration is complete.

[0069] When this final target mass is reached, the progress factor is equal to one. The dysfunctional regeneration is then completely finished. When motor 21 is stopped before the end of the dysfunctional regeneration, the progress factor is stored. If this factor exceeds a minimum progress threshold, the dysfunctional regeneration, even if not completely finished, is classified as sufficient.

[0070] During a vehicle stop, for a progression factor below the minimum progression threshold, the dysfunctional regeneration is resumed at the next engine restart 21 as soon as authorization conditions 1 are met and prohibition conditions 2 are lifted.

[0071] Reference 7 symbolizes the assignment of a progression factor to dysfunctional regeneration. When regeneration is successful (RG r), the progression factor is 1. A lower progression factor can be assigned to incomplete regeneration due to engine 21 stopping (Amfps), hence the reference between RG r and Amfps. The "regeneration in progress" information (Ri RG ec) and the "regeneration needed" information (Ri B RG) are also reset to the regeneration need value fixed at the first activation (B RG fa).

[0072] The progression factor allows you to track the progress of a regeneration and serves as a reference for stopping a malfunctioning regeneration when the vehicle is stopped, possibly for resuming this regeneration at the next start.

[0073] At the end of a complete or sufficient dysfunctional regeneration (RG r or Amfps), the soot mass estimates of the first 10 and third estimates 11 are updated with respect to the value given by the second soot mass estimate 12. This is referenced as Rm BF CC, for resetting the masses of the first estimate 10 in closed loop and the third estimate 11 under critical conditions.

[0074] It is understandable that malfunctioning regenerations do not need to be initiated for all driving profiles, as a gasoline engine can frequently guarantee the conditions for passive or functional regeneration. The method according to the invention is reserved for driving profiles that are highly unfavorable for the maintenance of regenerations.

[0075] To determine whether the method according to the invention is applicable, the vehicle's current driving profile is monitored. This current driving profile can then be compared with, or anticipated by, driving profiles identified as preventing regular full regenerations. If the vehicle's current driving profile matches one of the stored driving profiles, or if it is anticipated to be unfavorable for successful regeneration, a malfunctioning regeneration is initiated.

[0076] The invention relates to a motor vehicle powertrain comprising a spark-ignition internal combustion engine 21, an exhaust line 18, a control unit in charge of the operation of the internal combustion engine 21 and a monitoring unit for the particulate filter 22, the monitoring unit being able to be integrated into the control unit.

[0077] The supervisory unit in association with the engine control unit 21 or under the control of a diagnostic unit to detect if a regeneration is required, triggers a regeneration of the particulate filter 22 for a soot particle load in the filter 22 exceeding a predetermined minimum load threshold, the exhaust line 18 including a differential pressure sensor 19 at the terminals of the particulate filter 22.

[0078] According to the invention, the powertrain includes means for implementing a method of initiating a malfunctioning regeneration as previously described. The control unit or a diagnostic unit includes first means 10 for estimating a soot mass MsBF as a function of the pressure differential measured by the sensor 19 across the filter 22, second means 12 for estimating a soot mass as a function of the engine 21 emissions MsBO since the last regeneration, taking into account an estimate of the natural combustion of the soot since the last regeneration, and third means 11 for estimating a soot mass as a function of the engine 21 emissions MsCC, taken separately, with means for determining a safety multiplicative factor.

[0079] The control unit also includes means for comparing the three estimates 10 to 12 made and means for recalibrating the second estimate 12 at least on the first estimate 10 and, where appropriate, in addition with respect to the third estimate 11. The person skilled in the art has the necessary skills to modulate the recalibration of the second estimate 12, which is done mainly with respect to the first estimate 10 by taking into account the third estimate 11.

[0080] The invention is in no way limited to the embodiments described and illustrated, which have been given only by way of example.

Claims

1. Method of initiating a dysfunctional regenerating a filter (22) to particles of line (18) from engine exhaust (21) to thermal ignition equipping a motor vehicle, the regeneration called dysfunctional being initiated when a regeneration called functional or passive cannot take place due to a driving profile preventing it by not reaching a minimum regeneration temperature, by having insufficient driving time or by presenting an oxygen supply in the line (18) insufficient exhaust for its performance, the method comprising a step of identifying a running profile preventing functional or passive regeneration, a step of estimating a mass of soot running in the particulate filter (22) and a current load (Cs) of the filter (22) from the current mass (Msc) and, when the current load (Cs) is greater than a minimum threshold, a step of modifying the combustion parameters (McsRGa) for obtaining a temperature in line (18) greater than 600° and a mass of oxygen in the line (18) at least greater than 2% of the total mass of gas to effect regeneration dysfunctional, characterized in that the estimation step is done as a function simultaneously of three estimations (10 to 12) of masses from, firstly, a measurement of a pressure differential across the particulate filter (22), secondly , of an estimate (12) of the engine emissions (21) since the last regeneration taking into account an estimate of natural soot combustion since the last regeneration and, third, an estimate (11) of the emissions of the engine (21) taken in isolation to which a predetermined multiplicative factor is applied safety greater than 1 and, when a measurement of the pressure differential is available, the second estimate (12) is readjusted with respect to at least the first estimate (10).

2. Method of launching according to the preceding claim, wherein the dysfunctional regeneration of the particulate filter (22) is carried out if authorization conditions (1) are met and prohibition conditions (2) are lifted, the authorization conditions (1) being a current load (Cs) between the minimum threshold and a maximum threshold presenting a risk of damage to the filter (22) during regeneration, an implementation of the step of modifying the combustion parameters (McsRGa) with an engine temperature (21) greater than a predetermined minimum temperature and a driving time greater than a minimum duration, the prohibition conditions (2) being lifted if the vehicle has traveled a minimum distance since the last regeneration carried out.

3. Method of launching according to the preceding claim, in which the current charge (Cs) is obtained as a function of the current mass (Msc) divided by an internal volume (14) of the particle filter (22).

4. Method of launching according to any one of the two preceding claims, in which the modified combustion parameters (McsRGa) are, taken individually or in combination, an under-timing of an ignition advance leading to an increase in the temperature of the gases. exhaust in the line (18), cuts or modifications of fuel injection in the engine (21) with a richness lower than one for an oxygen supply in the line (18).

5. Method of launching according to any one of the three preceding claims, in which a time delay (16) is observed between an estimate of a current load (Cs) allowing a dysfunctional regeneration and the launching of the dysfunctional regeneration.

6. Method of launching according to any preceding claim, wherein during dysfunctional regeneration the running mass (Msc) is followed by the second and third estimates (12, 11) and a progression factor (6) is estimated of the dysfunctional regeneration based on a determination of a final target mass and, when this final target mass is reached, the progression factor is equal to one and, when the engine (21) is stopped before the end of the dysfunctional regeneration, the progression factor is stored with, when this factor exceeds a minimum progression threshold, a qualification of dysfunctional regeneration as sufficient.

7. Method of launching according to the preceding claim, in which, at the end of a complete or sufficient dysfunctional regeneration (RG r Ou Amfps), the soot mass estimates of the first and third estimates (10, 11) are updated, with respect to the value given by the second estimate (12) of the mass of soot.

8. Method of launching according to any one of the two preceding claims, in which, when the vehicle is stopped, for a factor lying below the minimum threshold of progression, the dysfunctional regeneration is resumed the next time the engine (21) is restarted. as soon as authorization conditions (1) are fulfilled and prohibition conditions (2) are lifted.

9. Method of launching according to any one of the preceding claims, wherein the running profile current monitoring of the vehicle is compared with identified or anticipated rolling profiles for not allowing regularly perform complete regeneration and if the profile current driving of the vehicle corresponds to one of the stored driving profiles or if it is anticipated to be unfavorable for a regeneration to be carried out, a dysfunctional regeneration is initiated.

10. A motor vehicle powertrain comprising an engine (21) heat to ignition, a line (18) to exhaust, a command and control unit in charge of operating the engine (21) and a thermal monitoring unit filter (22) particulate matter triggering regeneration of the particulate filter (22) for a load of soot particles in the filter (22) greater than a predetermined minimum load threshold, the exhaust line (18) comprising a sensor (19) of pressure differential across the terminals of the particle filter (22), characterized in that it comprises means for implementing a method for initiating a dysfunctional regeneration according to any one of the preceding claims, the unit of control command comprising first means for estimating (10) a mass of soot as a function of differential pressure reading from the sensor (19) across the filter (22), second means of estimation (12) of a mass of soot s as a function of the emissions of the engine (21) since the last regeneration, taking into account an estimate of the natural combustion of the soot since the last regeneration and the third means of estimating (11) a mass of soot as a function of the engine emissions (21) taken in isolation with means for determining a multiplicative safety factor as well as means for comparing the three estimates (10 to 12) made and means for resetting the second estimate (12) on at least the first estimate (10).